Heat
Treating
Processes
and Related
Technology
Introduction Heat treating is defined as heating and cooling a solid metal or alloy in such a way as to obtain desired conditions or properties. Reasons for heat treating include the following:
l
l
l l l
Remove stresses. such as those developed in processing a part Refine the gram structure of the steel used in a part Add wear resistance to the surface of a part by increasing its hardness, and, at the same time. increase its resistance to impacts by mamtaining a soft, ductile core
Iron-carbon equilibrium
diagram
l l l
Beef up the properties of &an economical grade of steel, making it possible to replace a more expensive steel and reduce material costs in a given application Increase toughness by providing a combination of high tensile strength and good ductility to enhance impact strength Improve the cutting properties of tool steels ltpgrade electrical properties Change or modify magnetic properties
The focus in this chapter is on heat treatments associated with getting the desired result.
and the technology
2 / Heat Treater’s Guide Fist, key components abstracts on:
of the heat treating
process are summarized
Second, practical, how-to information
in l
. Normalizing
l
l
hneding
l
l
Stress relieving Surface hardening Quenching/quenchants Tempering Cold/cryogenic treatments Furnace atmospheres
l l l l l
Heat
Treating
l l l l
by overview
atticles on:
Causes of distortion and cracking in quenching Stress relief heat treating Furnace atmospheres Cold and cryogenic treatments of steel Representative applications of heat treating furnaces Statistical process control of heat treating operations Practical applications of the computer in heat treating
Processes tion in resistance to brittle fracture. Lf a steel, such as austenitic stainless steel, is not prone to brittle fracture, residual stresses can cause stress-corrosion cracking (SCC). Warping is the common problem.
Normalizing The term normalize does not characterize the nature of this process. More accurately, it is a homogenizing or grain refining treatment, with the aim being unifotmity in composition throughout a part. In the thermal sense, normalizing is an austenitizing heating cycle followed by cooling in still or slightly agitated air. Typically, work is heated to a temperature of approximately 55 “C (100 “F) above the upper critical line of the iron-iron carbide phase diagram, and the heating portion of the process must produce a homogeneous austenitic phase. The actual temperature used depends upon the composition of the steel; but the usual temperature is around 870 “C (1600 “F). Because of characteristics inherent in cast steel, normalizing is commonly applied to ingots prior to working, and to steel castings and forgings, prior to hardening. Air hardening steels are not classified as normalized steels because they do not have the normal pearlitic microstructure typical of normalized steels.
Surface
A generic term denoting a treatment consisting of heating to and holding at a suitable temperature, followed by cooling at a suitable rate; used primarily to soften metals and to simultaneously produce desired changes in other properties or in microstructures. Reasons for annealing include improvement of machinability, facilitation of cold work, improvement in mechanical or electrical properties, and to increase dimensional stability. In ferrous alloys. annealing usually is done above the upper critical temperature, but time-temperature cycles vary widely in maximum temperature and in cooling rate, depending on composition of the steel, condition of the steel, and results desired. When the term is used without qualiftcation. full annealing is implied. When the only purpose is relief of stresses, the process is called stress relieving or stress relief annealing. In full annealing steel is heated 90 to I80 “C ( I60 to 325 “F”) above the A3 for hypoeutectoid steels and above the At for hypereutectoid steels, and slow cooled, making the material easier to cut and to bend. In full annealing, the rate of cooling must be very slow, to allow the formation of coarse pearlite. ln process annealing, slow cooling is not essential because any cooling rate from temperatures below At results in the same microstructure and hardness.
Hardening
These treatments, numbering more than a dozen, impart a hard, wear resistant surface to parts, while maintaining softer, tough interior which gives resistance to breakage due to impacts. Hardness is obtained through quenching, which provides rapid cooling above a steel’s transformation temperature. Parts in this condition can crack if dropped. Ductility is obtained via tempering. The hardened surface of the part is referred to as the case, and its softer interior is known as the core. Gas carburizing is one of the most widely used surface. hardening processes. Carbon is added to the surface of low-carbon steels at temperatures ranging from 850 to 950 “C ( I560 to 1740 “F). At these temperatures austenite has high solubility for carbon. In quenching, austenite is replaced by martensite. The result is a high-carbon, mattensitic case. Carburizing steels for case hardening usually have carbon contents of approximately 0.2%. Carbon content of a carburized case is usually controlled between 0.8 to I% carbon. Other methods of case hardening low-carbon steels include cyaniding, ferritic nitrocarburizing, and carbonitriding.
Annealing
Stress
is provided
Quenching/Quenchants Steel parts are rapidly cooled from the austenhizing or solution treating temperature, typically from within the range of 815 to 870 “C (1500 to 1600 “F). Stainless and high-alloy steels may be quenched to minimize the presence of gram boundary carbides or to improve the ferrite distribution, but most steels, including carbon. low-alloy, and tool steels, are quenched to produce controlled amounts of martensite in the microstructure. Objectives are to obtain a required microstructure, hardness, strength, or toughness, while minimizing residual stresses, distortion, and the possibility of cracking. The ability of a quenchant to harden steel depends upon the cooling characteristics of the quenching medium. Quenching effectiveness is dependent upon steel composition, type of quenchant, or quenchant use conditions. The design of a quenching system and its maintenance are also keys to success.
Relieving
Residual stresses can be created in a number of ways, ranging from ingot processing in the mill to the manufacture of the finished product. Sources include rolling, casting, forging, bending, quenching, grinding, and welding. In the stress relief process, steel is heated to around 595 “C (I IO5 “F), ensuring that the entire part is heated uniformly, then cooled slowly back to room temperature. Procedure is called stress relief annealing, or simply stress relieving. Care must be taken to ensure uniform cooling, especially when a part has varying section sizes. If the cooling rate is not constant and uniform, new residual stresses, equal to or greater than existing originally, can be the result. Residual stresses in ferritic steel cause significant reduc-
Quenching
Media
Selection here depends on the hardenability of the steel, the section thickness and shape involved, and the cooling rates needed to get the desired microstructure. Typically, quenchants are liquids or gases. Common liquid quenchants are: l l l l
Oil that may contain a variety of additives Water Aqueous polymer solutions Water that may contain salt or caustic additives
Heat Treating Processes and Related Technology / 3 Most common gaseous quenchants are inert gases, including helium, argon, and nitrogen. They are sometimes used after austenitizing in a vacuum. A number of other quenching media and methods are available, including fogs, sprays, quenching in dry dies and fluidized beds. Ln addition, some processes, such as electron-beam hardening and high frequency pulse hardening are self-quenching. Very high temperatures are reached in the fraction of a second, and metal adjoining the small. localized heating area acts as a heat sink, resulting in ultrarapid cooling.
Tempering In this process, a previously hardened or normalized steel is usually heated to a temperature below the lower critical temperature and cooled at a suitable rate, primarily to increase ductility and toughness, but also to increase gram size of the matrix. Steels are tempered by reheating after hardening to obtain specific values of mechanical properties and to relieve quenching stresses and ensure dimensional stability. Tempering usually foUows quenching From above the upper critical temperature. Most steels are heated to a temperature of 205 to 595 “C (-NO to I I OS “F) and held at that temperature for an hour or more. Higher temperatures increase toughness and resistance to shock, but reductions in hardness and strength are tradeoffs. Hardened steels have a fully martensitic structure. which is produced in quenching. A steel containing 100% martensite is in its strongest possible condition, but freshly quenched martensite is brittle. The microstructure of quenched and tempered steel is referred to as tempered martensite. Martempering of Steel. The term describes an interrupted quench from the austenitizing temperature of certain alloy, cast, tool, and stainless steels. The concept is to delay cooling just above martensitic transformation for a period of time to equalize the temperature throughout the piece. Minimizing distortion, cracking, and residual stress is the payoff. The term is not descriptive of the process and is better described as marquenching. The microstructure after martempering is essentially primary martensite that is untempered and brittle. Austempering of Steel. Ferrous alloys are isothermally transformed at a temperature below that for pearlite formation and above that of martensite formation. Steel is heated to a temperature within the austenitiz-
Causes
of Distortion
and Cracking
This problem usually is the result of an imbalance in internal residual stresses that can lead to cracking, ranging from microcracking to bulk failure of a part, Ref I. Factors, singly or in combination, that can influence the nature and extent of shape distortion during quenching include: l l l l l l l
Steel composition and hardenability Geometry of part Mechanical handling Type of quenching fluid Temperature of quenchant Condition of quenchant Circulation (agitation) of quenchant
Composition The quenchant
ing range, usually 790 to 9 I5 “C ( I455 to 1680 “F); then quenched in a bath maintained at a constant temperature, usually in the range of 260 to 400 “C (500 to 750 “F); allowed to transform isothermally to bainite in this bath; then cooled to room temperature. Benefits of the process are increased ductility, toughness, and strength at a given hardness; plus reduced distortion that lessens subsequent machining time, stock removal, sorting, inspection. and scrap. Austempering also provides the shortest possible overall time cycle to through harden within the hardness range of 35 to 55 HRC. Savings in energy and capital investment are realized. Maraging Steels. These highly alloyed, low-carbon, iron-nickel martensites have an excellent combination of strength and toughness that is superior to that of most carbon hardened steels, and are alternatives to hardened carbon steels in critical applications where high strength and good toughness and ductility are required. Hardened carbon steels derive their strength from transformation hardening mechanisms, such as martensite and bainite formation, and the subsequent precipitation of carbides during tempering. Maraging steels, by contrast, get their strength from the formation of a very low-carbon, tough, and ductile iron-nickel martensite, which can be further strengthened by subsequent precipitation of intermetaUic compounds during age hardening. The term marage was suggested by the age hardening of the martensitic structure.
Cold and Cryogenic
Treatment
of Steel
Cold treatment can be used to enhance the transformation of austenite to martensite in case hardening and to improve the stress relief of castings and machined parts. Practice identities -84 “C (-120 “F) as the optimum cold treatment temperature. By comparison, cryogenic treatment at a temperature of around -190 “C (-3 IO “F), improves certain properties beyond the capability of cold treatment. Furnace Atmospheres. Atmospheres serve a variety of functions: acting as carriers for elements used in some heat treating processes, cleaning surfaces of parts being treated in other processes, and providing a protective environment to guard against adverse effects of air when parts are exposed to elevated temperatures. Principal gases and vapors are air. oxygen, nitrogen. carbon dioxide and carbon monoxide, hydrogen, hydrocarbons (i.e., methane, propane, and butane), and inert gases, such as argon and helium.
during
Quenching
Part Geometry Two considerations
here:
I. Quenching at the slowest possible speed as dictated by thickest section of the part 2. Or resorting to hot oil quenching techniques (more later)
Mechanical
Handling
Care is advised because steel in the austenitic condition is only one-tenth as strong as it is at room temperature. Avoid dropping parts into the bottom of a quench tank; and when continuous furnaces are used, quench chute design can cause damage when thin section parts strike pick-up slots in conveyor systems (see Figure).
and Hardenability Type of Quenching
selected should:
I. Just exceed the critical cooling rate of the steel used 2. Provide a low cooling rate in the Ms to Mr transformation Compromises in cooling rate often are necessary range of steels with a range of cooling rate.
range
to accommodate
a
Fluid
The importance of the characteristics of a quenchant during the three stages of cooling (vapor phase, boiling phase, and convection phase) is illustrated by an example involving precision auto transmission gears (see Figure). During oil quenching, vapor retention in tooth roots, combined with the onset of boiling on flanks can cause “‘unwinding” of thin section gears. Use of accelerated oils with special additives that reduce the stability
4 / Heat Treater’s
Guide
Schematic continuous
heat treatment installation.
Ref 1
Example: Because PAG (a polymer quenchant) has higher cooling rates than oils in the convection phase, parts are more susceptible to distortion. Use of PAG requires careful consideration to steel hardenability, part section size(s), and surface finishes. By comparison, other polymer quenchants (ACR. PVP, PEO) have cooling rates similar to those of oils, which means they can be applied in treating critical alloy steel parts outside the scope of PAG quenchants. which are suitable in quenching plain carbon, low-alloy, carburized steels, or higher alloy steel parts with thick section sizes.
Quenchant
Vapor retention in gear tooth roots during oil quenching. Ref 1
Temperature
In conventional quenching, the surface and thinner sections of a part cool to the his temperature and are beginning to transform while center and thicker sections are still in the soft, austenitic condition. This means that when soft sections begin to transform, their changes in volume are restricted by the hard. brittle martensite previously formed on surfaces and thin sections, creating stresses that can lead to distortion or to quench cracking. Hot oil quenching, a two-step process, is one remedy. Parts are Fu-st quenched in specially formulated oils, usually at temperatures within the range of I20 to 300 ‘C (250 to 390 “F). depending on part complexity and tendency to distort. Holding time at the temperature chosen is based on the time required to obtain a uniform temperature throughout a part. In the next step, parts are removed from the oil and cooled slowly in a furnace containing an atmosphere (see Figure).
Hot oil quenching techniques to reduce distortion.
of the vapor phase and promote boiling in cooling is the payoff.
Convection
is one remedy. Greater uniformity An alternative is marquenching in hot oil ( I50 to 200 “C, or 300 to 390 “F’). The hlS temperature of typical engineering steels is in the 250 to 350 “C range (480 to 660 “F).
Phase Characteristics
A temperature of 300 “C (570 “F) generally is accepted as the nom1 for cooling in this phase because it is within the M&t temperature range of a number of different engineering steels, and therefore a critical consideration in controlling distortion. Typical values for several types of quenchants are as follows: Quencbant Normal sped oil Acceleratal oil Polymers PAG (polyalk\ylene glycol) ACR (sodium polyacrylate) PVP(polyvinyl pyrrolidene) PEO(polyethyl oxazolrne)
Ref 1
Cooling rate at 300 ‘C (570 OF) “C/s s-15 IO-15
Condition
Regular monitoring of the quenching fluid is preferred practice. The minimum: testing for acidity and water content of quenching oil and checking the concentration of polymer quenchants. An added control: periodic evaluation of quenching characteristics. Increases in quenching speeds, especially in the convection phase, are a common problem. Possible causes include: l
30-80 I o-25 I o-25 I O-30
of Quenchant
l
Contamination of quenching oils with water. As little as 0.05% water can have a dramatic effect on the maximum cooling rate and on the convection phase cooling rate. Oxidation of mineral oils reduces the stability of the vapor phase and accelerates maximum cooling rates.
Heat Treating Processes and Related Technology / 5
l
Contamination or thermal degradation of polymer quenchants increases the cooling rate in the convection phase. Higher polymer concentrations are a parIial solution.
Circulation of quenchant is important in maintaining a uniform bath temperature and in assisting the breakdown of the vapor phase. The degree of agitation has a significant influence on the cooling rates of both quenching oils and polymer quenchants. With increases in the agitation of oil, three things happen: l l l
Duration of the vapor phase is shortened Maximum cooling rate rises Cooling rate in the convection phase also goes up
The last named effect adds to the risk of cracking, meaning that excessive agitation of oils should be avoided. Agitation of polymer quenchants has a pronounced effect on the vapor phase and maximum cooling rate, but little effect on the cooling rate in the convection phase. Vigorous agitation of polymer quenchants normally is recommended to ensure uniform quenching characteristics, a practice that does not enhance the risk of cracking.
Stress
Relief
Heat
Treating
Finally, the direction influence on distortion. provide relief.
of quenchant flow over the workpiece can have an Reversing the direction of flow, for example, can
Reference I. R.T. van Bergen, conference paper, ‘The Effects of Quenchant Media Selection and Control of Distortion of Engineered Steel Parts.” Houghton Vaughan plc. Birmingham. England, ASM Conference Proceedings, “Quenching and Distortion Control,” 1992
Other References Quenching Principles and Practice, Houghton Vaughan plc, UK G.E. Hollox and R.T. von Bergen, Heat Treatment of Metals, 1978.2 hlEl Course 6. Heat Processing Technology, ASM International, 1977 R.T. von Bergen, Heat Treatment of Metals, 1991.2
of Steel
Residual stresses are built up in a part during the course of a manufacturing sequence. Technically, a part is stressed beyond its elastic limit and plastic flow occurs.
long distance or highly localized. Postweld heat treating has two objectives: relief of residual stresses and the development of a specilic metallurgical structure of properties (Ref 4.5).
Causes
Relieving
Bending, quenching, grinding, and welding are among the major causes of the problem (see adjoining Figure). Bending a bar during fabrication at a temperature where recovery cannot occur (as in cold forming) can cause a buildup on residual tensile stresses in one location, and a second location, 180” from the Fust location, will contain residual compressive stresses (Ref I). Quenching of thick sections results in high residual compressive stresses on the surface of a part. They are balanced by residual tensile stresses in the interior of the part (Ref 2). Residurtl stresses caused by grinding can be compressive or tensile in nature. depending on the grinding operation. Such stresses tend to be shallow in depth, but they can cause warping of thin parts (Ref 3). In welding, residual stresses are associated with steep thermal gradients inherent in the process. Stresses may be on a macro-scale over a relatively
Relief is a time-temperature related phenomenon rically correlated by the Larson-hliller equation:
Examples of the causes of residual stresses: (a) Thermal due to welding.
(c) Residual
stresses
due to grinding
distortion
Residual
Stresses (see Figure), paramet-
where T is the temperature (Rankin) and I is time in hours. Example: holding a part at 595 “C (I I05 “F) for 6 h provides the same result as heating at 650 “C ( 1200 “F) for I h. Other Factors. Creep resistant materials such as chromium bearing, low-alloy steel and chromium rich, high-alloy steel normally require higher stress relief temperatures than con\ entional low-alloy steels. Typical treatment temperatures for low-alloys are between 595 and 675 “C (I I05 and 1245 “Fj. Temperatures required for the treatment of high alloys, by comparison. range from 900 to 1065 “C ( 1650 to 1950 “F).
in a structure
due to heating
by solar radiation.
(b) Residual
stresses
6 / Heat Treater’s Guide
Relationship between time and temperature in the relief of residual stresses in steel
925 “C (895 to 1695 “F). However,
at the higher end of this range stress-corrosion cracking can occur (Ref 6). Solution annealing temperatures of approximately 1065 “C (1950 “F) are frequently used to reduce residual stresses in these aBoys to acceptably low levels.
References I. GE. Dieter, Mechanical Merallurgy, 2nd ed, McGraw-Hill, 1976 2. J.O. Almen and RH. Black, Residual Stresses and Fatigue in Merals, McGraw-Hill, 1963 3. Machining, Vol 3, 8th ed, Merals Handbook, American Society for Metals, 1967, p 260 4. N. Bailey, The Metallurgical Effects of Residual Stresses, in Residual Stresses, The Welding Institute, I98 I, p 28-33 5. C.E. Jackson et al., Metallurgy and Weldabili& of Sleek, Welding Research Council, 1978 High alloys such as austenitic stainless steels are sometimes treated at temperatures as low as 400 “C (750 “F). But in this instance stress reduction is modest. Better results are obtained at temperatures ranging from 480 to
Furnace
6. Properties and Selecrion: Stainless Sleels, Tool Materials and Special Putpose Metals, Vol 3.9th ed, Metals Handbook, American Society for Metals,
1980, p 4738
Atmospheres
Properties of common gases and vapors are listed in Table I. They include air, oxygen, nitrogen, carbon dioxide, carbon monoxide, hydrogen, water vapor, hydrocarbons, and inert gases. Ref I. Air provides atmospheres in furnaces in which protective atmospheres are not used. Air is also the major constituent in many prepared amiospheres. The composition of air is approximately 79% nitrogen and 2 I % oxygen, with trace elements of carbon dioxide. As an atmosphere, air behaves like oxygen, the most reactive constituent in air. Oxygen reacts with most metals to form oxides. It also reacts with carbon dissolved in steel, lowering surface carbon content. Nitrogen in its molecular state is passive to ferrite and can be used as an atmosphere in annealing low-carbon steels; as a protective atmosphere in heat treating high-carbon steels, nitrogen must be completely drysmall amounts of water vapor in nitrogen cause decarburization. Molecular nitrogen is reactive with many stainless steels and can’t be used to heat treat them. Atomic nitrogen, which is created at normal heat treating temperatures, is not a protective gas-it combines with iron, forming finely divided nitrides that reduce surface hardness.
Carbon dioxide and carbon monoxide are used in steel processing atmospheres. At austenitizing temperatures, carbon dioxide reacts with surface carbon to produce carbon monoxide, a reaction that continues until the supply of carbon dioxide is exhausted and the steel surface is free of carbon. Hydrogen reduces iron oxide to iron. Under certain conditions, hydrogen can decarburize steel, an effect that depends on furnace temperature, moisture content (of gas and furnace), time at temperature, and carbon content of the steel. Water vapor is oxidizing to iron and combines with carbon in steel to form carbon monoxide and hydrogen. It is reactive with steel surfaces at very low temperatures and partial pressures. It is also the principal cause of bluing during cooling cycles. Carbon hydrocarbons are methane (Cb). ethane (C2H6). propane (C$-Js), and butane (CtHtu). They impart a carburizing tendency to furnace atmospheres. Inert gases are especially useful as protective atmospheres in the thermal processing of metals and alloys that can’t tolerate the usual constitu-
Table 1 Properties of Common Gases and Vapors
Gas
Chemical symbol
Air
Approximate molecular weight
k&m3
lb/d’
I.293 0.760 0.178 I.965
0.0807 0.047-l 0.0111 0.1228 0.0780 0.0112 0.0056 0.0447 0.0780 0.0892 0.1229 0. I785
Density(a)
AINllOllitl
NH3
Argon Carbon dioxide Carbon monoxide Helium Hydrogen Methane Nitrogen Oxygen Pv= SulFurdioxide
Ar CO?
28.97(c) 17.03 39.95 44.02
CO
28.01
I.250
He H? CH-I N? 02
4.00 2.02 16.04 28.01 32.00
0.179 0.090 0.716 I.250 I.429 I.968 2.860
C3Hx
SO?
44.09
64.06
(a) Standard temperature and pressure: 0 “C (32 “F) and 760 mm Hg. (b) Relative is the average molecular weight of its constituents.
density compared
SpCifiC
to air. (c) Because air IS a mixture,
gravity(b) l.ooo 0.588 I.380 1.520 0.967 0.138 0.070 0.552 0.968 I.105 I.522 2.212
it does not have a true molecular
weight. This
Heat Treating Processes and Related Technology / 7 Table 2 Classification Dfscription
Cla5.S
101 102 201 202 301 302 402 501 so2 601 621 622
and Application
Lean exothemic Rich exothermic Lean prepared nitrogen Rich prepared nitrogen L.eaoendothemic Rich endothermic Charcd Leanexothemric-endothermic Rich enothennic-endothermic Dissociated ammonia Lean cornbusted ammonia Rich cornbusted ammonia
of Principal Furnace Atmospheres
Common application
NZ
Oxide coating of steel Bright annealing; copper brazing; sintering Neutral heating Annealing, brazing stainless steel Clean hardening Gas carburizing Carburizing Clean hardening Gas carburizing Brazing. sintering Neutral heating Sintering stainless powders
86.8 71.5 97. I 75.3 45.1 39.8 64. I 63.0 60.0 25.0 99.0 80.0
reactive metals and their alloys. Argon costs about half as much as helium, and is frequently favored; air contains approximately 0.93% argon by volume, and is recovered by liquefying air, followed by the fractionation of liquid air: helium is recovered from natural g,as deposits by cryogenic methods.
ents in protective
Classifications The American tions:
of Prepared Gas Association
Atmospheres
is the source of the following
classitica-
Class 100, exothermic base: formed by the combustion of a gas/air mixture; water vapor in the gas can be removed to get the required dew point Class 200, prepared nitrogen base: carbon dioxide and water vapor have been removed Class 300. endothermic base: formed by the reaction of a fuel gas/air mixture in a heated, catalyst tiller chamber Class 400, charcoal base: air is passed through a bed of incandescent charcoal Class 500, exothermic-endothermic base: formed by the combustion of a mixture of fuel gas and air; water vapor is removed and carbon dioxide is reformed to carbon monoxide by reaction with fuel gas in a heated, catalyst tilled chamber Class 600. ammonia base: can consist of raw ammonia. dissociated ammonia, or combusted dissociated ammonia with a regulated dew point Subclassifications supplement the six basic classitications for prepared atmospheres-the two zeros in the latter are replaced by the two-digit numbers that follow. These atmospheres are prepared by special techniques. l l l
l
l
l
l
l
l
l
01: prepared from a lean air and gas mixture 02: prepared 6om a rich air and gas mixture 03 and 04: preparation is completed within the furnace itself without the use of a special machine or generator 05 and 06: original base gas is subsequently passed through incandescent charcoal before admission to work chamber 07 and 08: raw hydrocarbon fuel gas is added to base gas before admission to work chamber 09 and IO: raw hydrocarbon fuel gas and rah dry anhydrous ammonia are added to base gas before admission to work chamber I I and 12: combustible mixture of chlorine, hydrocarbon fuel gas and air is added to base gas before admission to work chamber I3 and 14: all sulfur or all sulfur and odors are removed from gas before admission to work chamber IS, 16, I7 and 18: lithium vapor is added to base gas before admission to work chamber I9 and 20: gas preparation is completed inside the furnace chamber bith the addition of lithium vapor
co
Nominal composition, ~01% co2
I.5 IO.5 1.7 II.0 19.6 20.7 31.7 17.0 19.0
IO.5 5.0
82
CB,
1.2 12.5 I.2 13.2 34.6 38.7 I.2 20.0 2 I .o 75.0 I.0 20.0
0.4
OS 0.5 0.3 0.8 ... .
Table 3 Potential Hazards and Functions of Heat Treating Atmosphere-Constituent Gases Potential hazard Stole Gas
Flammable
Nitrogen Hydrogen Carbon monoxide
Toxic
Yes Yes
Yes Yes
Yes
Carbon dioxide
Yes
Natural gas
Yes
Ammonia Methanol
Yes Yes
Yes Yes
Yes Yes
Table 4 Physiological
Atmosohere
a5phyknt
..
fUll&Oll
tnell Strongly reducing Carburizing and mildly reducing Oxidizing and decarburizing Strongly carburizing and deoxidizing Strongly niniding Carbon monoxide and hydrogen generating
Effects of Ammonia
Conceotrstion, Physiological
mm
30
First perceptible odor Slight eye irritation in a few individuals Noticeable irritation of eyes and nasal passages after a few minutesofexposure Were irritation of the duoat, nasal passages. and upper respiratory tract Severe e)e irritation; no permanent effect if the exposure is limited to less than r/z h Serious coughing, bronchial spasms; less than ‘/z h of exposure may be fatal Serious edema strangulation, asphyxia; almosl immediately fatal
-lo I00 m 700 1700 moo
l
l
l
effects
21 and 22: base gas is given an additional special treatment before admission to work chamber 23 and 24: steam and air ‘are added and in conjunction with a catalyst in a generator convert carbon monoxide to carbon dioxide, which is then removed 25 and 26: steam is added to a generator containing a catalyst, converting CHJ to Hz and CO?, which is then removed Few
cially
of the atmospheres important.
Principal
in the subclassification furnace
atmospheres
category and their
are commer-
common
appli-
cations are listed in Table 2. Potential hazards in the use of constituents in heat treating atmospheres and their functions are listed in Table 3. Physiological effects of ammonia are listed in Table 4, and physiological effects of carbon monoxide are given in Table 5.
8 / Heat Treater’s Guide Exploswe
ranges of typical
atmosphere
constituents
are:
their use as intentional ture operations.
Concentration
Constituent
in Air Q
Hbdrogcn
-I o-74
Carbon mono\idc hlrtic Ammonia hkthm0l
12.5-71 5.3-13 15.0-28
Endothermic-Based
agents or in special, low tempera-
Atmospheres
These atmospheres are suitable for practically all furnace processes requiring strong reducing conditions. Their most common applications are as carrier gases in gas carburizing and carbonitriding operations. Other applications include bright hardening of steel. carbon restoration in forg-
6 7-36
Exothermic-Based
surface oxidizing
Atmospheres
Class 100 atmospheres of this type are \\idelj used as lo\rer cost alternatives to other atmospheres. The) are available in two classes: rich (class 102) and lean (class 101). The rich types have moderate reducing capabilities of IO to 2 I% combined carbon monoxide and hydrogen. The lean types. usually with I to 1 Q combined carbon monoxide and hydrogen. have minimal reducing qualities. Rich exothermic atmospheres are used mainlj in the tempering of steel and sintering of powder meval compacts. Heat treating applications of lean exothermic atmospheres are generally limited, particularI) in the treatment of ferrous metals. Exceptions include
Table 5 Physiological
Effects of Carbon Monoxide
Concentralion, PPm
Physiological effects Allo\\sble for an exposure of several hours Can be inhaled for I h without appreciable effect Causes a barely appreciable effect tier I h of exposure Causes unpleasant symptoms. hut not dangerous aher I h
100
400 6ofl IO00 I ml
Dangerous for exposure of I h Fall for exposure of less than I h
4000
Table 8 Comparison of Generated Atmosphere Systems Versus Commercial Nitrogen-Based Generated ppe of atmosphere
Designation
Application
Protacti\e
Annealing
Reacti\c
Brazing Siniering
Carbon controlled
Hardening Carburizing Decarburizing
Table 7 Compositions
Exolhermi~ Dissociated ammonia Exothermic Dissociated arnmon~a Endothemlic Dissociated ;unmonia Endothemlic Endothemlic Erolhermic
atmosphere Nominal composition, N2 HZ
70-100
O-16
25 70-80 75 40 2s 10 10 85
7s IO- I6 75 -IO 75 40 10 5
% CO O-II
8-11 70 20 20 3
Designation
Systems
Nitrogen-based atmosphere Nominal composition, N? co 82
Niuwgen-hydrogen Nitrogen-methanol Nitrogen-hydrogen Niaogen-hydrogen
9% IO0 91-100 60-90 95
O-IO O-h IO-40 5
o-3 ,..
Nitrogen-hbdrogcn Nitrogen-merhanol Nitrogen-mehane Nitrogen-tnclhanol Nitrogen-hydrogen
95 85 97 40 90
5 IO I JO IO
5 I 30
of Protective Generated Atmosphere and Commercial Nitrogen-Based Furnace
atmosphere
analysis,
Carbon steel sheet. rube. wrc Carbon steel rod
Copper n ire. rod .Alunlinurn Skinless
sheet steel sheet. wire
Srainless sleel tube
hlalleahle Nick-uon
iron anneal laminaoons
atmosphere
Exolhermic-purified N:-S5 Hz E\othetis-puritird Exothermic-cndolhemtiii N,- I!“1 C,H, N,-55, H>-3=c CH, N;-3% Ct?
N:
blend
I30 95 IO0 75 97 90 91 86 99 86 100 3 db 25 7s 98 97 25 85
HZ
co
CH,
8 I5 1 7 6
8 I 7
7 ; I
;
I
15 I00 -10 7s 100 25
I 75 IS
2 1
I
CH,
:::
I
Atmosphere Systems
% ‘Itace
Input
Application
%
impurities
HZ0
Co2
0.01 0.00 I 0.01 0.01 0001 0.001 0001 3 0.001 3 0.001 O.GOl 0.0005 0.000.5 0.001 O.ooOS 0.005 0.01 0.001 0.001 0001
0.5 0.5 0.5 0.01 0.0 I 0.0 I II II
0.5 0.2
Heat Treating Processes and Related Technology / 9 Table 8 Compositions
of Reactive Atmospheres for Brazing and Sintering Applications Furnace atmosphere analysis, %
Input atmosphere
Application Copper bmze carbon sleel
Silver braze stainless steel hledlize ceramics Glass-to-metal seal Carbon steel sintering (6.4 to 6.8 g/cm’. or 0.23 1025 Ib/ii.~density. cO.4%Cc)
Carbon steel sintering (6.8 to 7.2 g/cm’, or 0.25 to0.261b/in.3densirq.>0.4QC)
Brass. bronze simering
Stainless steel sintering Tungsten carhide Sintering and brazing Sintering Presinrering Nickel sintering
ings and bar stock, and the sintering requiring a reducing atmosphere.
Prepared
Nitrogen-Based
NZ
82
Exothetic-rich Endothermic N,-55% H, N;-3% CH,OH Dissociated ammonia N2-25’% H, Dissociatei ammonia t Hz0 N,-10% H--?-B H,O E~othermi~ N,- 10%.H,-L?q, H,O Endother&
70 40 95 91 1s 75 2s 90 75 88 40
I-l 39 5 6 7s 25 75 IO 9 I0 39
N2-S% H, Endothermic N2-endothermic
9.5 -lo 87
5 39 8
N+? CH,OH N,-8% H1-2Q CH Dissociated ammoha Endothermic NvIO% H, Dissociates ammonia HZ
76 90 2s -lo 90 25
I6 8 75 39 10 75 100
Dissociated ammonia H, N;-20Q H, Dissociated ammonia N,-IO% H,
2s
7s 100 20 75 IO
of powder
metallurgy
80 25 90
compacts
Atmospheres
Applications in this instance extend to almost all heat treatments that do not require highly reducing atmospheres. They are not decarburizing and can be used in annealing. normalizing, and hardening of medium- and high-carbon steels: the low carbon monoxide content of lean gases makes them suitable for heat treating lou-carbon steels. Because of their low dew point and virtual absence of carbon dioxide, these atmospheres (in the absence of oxygen-bearing contaminants introduced in furnace operations) are neither oxidizing or decarburizing, in contrast with exothermic-based atmospheres. In addition, they are lower in cost than all but one type of protective atmosphere: the exothermics. Nitrogen-based atmospheres enriched with methane or other hydrocarbons are used occasionally as carrier gases in annealing. gas carburizing. and carbon restoration; but endothermic and other protective atmospheres are generally preferred for their high carbon potentials and greater ease of control. Lean. nitrogen-based atmospheres are also used in large. seni-continuous and continuous annealing furnaces. Their rich counterparts can be used in the sintering of iron powder compacts. Generated atmosphere systems and commercial. nitrogen-based systems are compared in Table 6.
Commercial
Nitrogen-Based
Atmospheres
These products fall into three major categories. based on function: protective atmospheres, reactive atmospheres, and carbon-controlled atmospheres.
co
CE4
II I9
I 2
3
7 I9
2
I9 -I
7 ;
7 I
I I
I9
2
‘Itace impurities 820 Co2 0.0s 0.05 0.001 0.001 0.001 0.001 3 2 3 2 0.05 0.001 0.0s 0.01 0.005 0.005 0.00 I 0.05 0.00 I 0.001 0.001
4 0.1 0.01
6 0. I 0.2 0.05 0.05
0.01 0.3
0.001 0.001 0.001 0.001 0.001
Protective atmospheres prevent oxidation or decarburization during heat treatment. Typical applications include batch and continuous annealing of most ferrous metals. Reactive atmospheres have concentrations of reactive gases greater than S%--to reduce metal oxides or to transfer small amounts of carbon to ferrous surfaces. Hydrogen and carbon monoxide are usual reactive components. Typical applications: brazing. sintering powder metal compacts, and powder metal reduction. Carbon-Controlled Atmospheres. Their main function is to react I{ ith steel in a controlled manner so that significant amounts of carbon can be added to or removed from the surface of a steel. Typical atmosphere components can include up to SO8 hydrogen, 5 to 20% carbon monoxide, and traces (up to 3%) of carbon dioxide and water vapor. Most common apptications are carburizing and carbonitriding machined parts. neutral hardening. decarburization of electrical laminations, sintering of powder metals, and carbon restoration of hot worked or forged materials. Advantages of commercial. nitrogen-based atmospheres include the technical viability of substituting them for generated ahnospheres in most heat treating operations. Compositions of protecti\ e generated atmospheres and commercial, nitrogen-based systems are listed in Table 7. Compositions of reactive atmospheres for brazing and sintering are given in Table 8. Compositions of carbon-controlled atmospheres for selected applications are summarized in Table 9.
Dissociated,
Ammonia-Based
Atmospheres
Applications include: bright heat treating of some nickel alloys and carbon steels; bright annealing of electrical components. and use as a carrier mixed gas for certain nitriding processes, including the Floe nitriding system. a method of controlling the formation of white layer.
10 / Heat Treater’s Guide Table g Compositions
of Carbon-Controlled
Atmospheres for Selected Applications Furnace
Input Neutral harden
Carburize
Carbonitride
Lamination decarburize
atmosphere
NZ
82
Endothermic + CH, N,-2% CH,. or 1% C,H,
39 97 8-l 37 37 70 55 36 36 68 53 75 83 79
40 I IO Xl 40 I6 28 xl 40 I8 30 9 IO IO
N,-5% CH,OH-I% CH, Endothetic + CH, N?-20% CH,OH + CH, N--17% CH,-4% CO, N;-20%. CH,-5% Hz6 Endothermic + CH, + NH, N,-20% CH,OH + CH, + NH, NJ- 17% CH,-4% CO, + NH, N,-20% CH,-5% H,O t NH, Exothermic + H,O N?- 10% H,-4% H,O Nz-5%. CH,OH-4C Hz0
Table 10 Physiological Effects of Contamination by Ammonia in Various Concentrations Ammonia concentration in air, ppm 53
100 30@5cKl 408 698
17’0 2s00-4500 5ooo- lO.ooo
Physiological
of Air
effect
Smallest concentration at which odor can he detected Maximum concenaation allowable for prolonged exposure Maximum concenuation allowable for short exposure (‘/?-I h) Least amount causing immediare irritation to the throat Least amount causing immediate irritation to the eye Least amount causing coughing Dangerous for short exposure (‘12 h) Rapidly fatal for short expsure
atmosphere
analysis,
co
Hydrogen
Atmospheres
T’he commercially available product is 98 to 99.98 pure. All cylinder hydrogen contains traces of water vapor and oxygen. Methane. nitrogen, carbon monoxide, and carbon dioxide may be present in very small amounts as impurities. Hydrogen is a powerful deoxidizer, and its deoxidizing potential is limited by moisture content only. Its thermal conductivity is about seken times that of air. Its main disadvantage is that it is readily absorbed by most common metals, either by occlusion or by chemical composition at elevated temperature. Absorption can result in serious embrittlement. especially in high-carbon steels. It may also reduce oxide inclusions in steel to form water, which builds sufftcient pressure at elevated temperatures to cause intergranular fracture of steel. Dry hydrogen will decarburize highcarbon steels at elevated temperature by reacting with carbon to form methane.
lhwe HZ0
C&
I9 I 5 I8 I8 7 IO I8 I8 7 IO 7 I 2
0.05
2 I I 5 5 7 7 5 5 7 7
0.001 O.OOS 0.0s 0.05 O.OOS 0.0 I 0.05 0.05 0.005 0.01 3 3 3
impurities CO2
0.1 0.01 0.01 0.1 0.1 0.05 0.05 0. I 0.1 0.05 0.05 6 3 6
Table 11 Equipment Requirements for Sintering Stainless Steel Powder Metallurgy Parts in Hydrogen Production
requirements
Load weight. kg (lb) Heating cycle, min Output per hour, kg (Ih) Equipment
9(30) 40 l4(3OJ
requirements
Bumoff furnace Size ofhearth. mm (in.) Length of cooling chamber. m (ft) Power, hp (kW) *rating temperature, “C (“F) Atmosphere. m’/h tft3/h) High-heat furnace Size ofhearth, mm (in.)
This atmosphere (class 601) is a medium cost product which provides a dry, carbon-free source of reducing gas. Typical composition: 75% hydrogen, 2YZ nitrogen, less than 300 ppm residual ammonia. Dew point is less than -SO “C (- 60 “F). High hydrogen content provides a strong deoxidizing potential, an advantage in removing surface oxides or preventing oxide formation during high temperature heat treatment. Care is advised in selecting heat processing applications that might result in unwanted hydrogen embrittlement or surface nitriding reactions. Physiological effects of the contamination of air with ammonia in different concentrations are set forth in Table IO.
5%
Lengthofcoolingchamber.mm(li~ Power. hp (kW) Operating temperature. “C (“F)
Pusher. electrically heated; forced circulation 25Sby lSOby915(lOby6by36) I .8 (6) 17 (‘0) 43 (800)
Dissociated ammonia, 4.2 ( 150) OPen chamber, electrically heated; front push rear pull 255by610(10by24)(preheating) 255 by 9lS(lOby 36)(high heating) U(8) 17(35) I275 (2325)
Hydrogen best suited for metallurgical purposes is made by the electrolysis of distilled water. In most heat treating procedures requiring hydrogen, hater vapor and oxygen are objectionable, and hydrogen must be puritied before it can be used. Applications for dry hydrogen include the annealing of stainless steels, low-carbon steels, electrical steels, some tool steels. nickel brazing of stainless steel and heat resisting alloys, the annealing of metal powders, and the sintering of powder metal compacts. Equipment requirements for sintering stainless steel powder metallurgy parts in hydrogen are found in Table I I.
Steam Atmospheres Scale-free tempering and stress relieving of ferrous metals in the temperature range of 3-U to 650 “C (655 to I200 “F) are among the applications here. Steam causes a thin, hard, and tenacious blue-black oxide to form on a metal surface. The film, approximately 0.00127 to 0.008 mm (0.00005 to 0.0003 in.) thick, improves properties of various metal parts. Steam treating decreases the porosity of sintered iron compacts and provides increased compressive strength and resistance to wear and corrosion. Steam penetrates the pores of compacts and forms the oxide internally as well as on the surface. The oxide seals pores and partially fills voids.
Heat Treating Processes and Related Technology / 11
Exothermic and Endothermic Furnace Atmospheres.
Source:
Cast iron and steel parts, treated at 345 “C (655 “F) or higher, have increased resistance to wear and corrosion. Before parts are processed their surfaces must be clean and oxide-free, to permit the formation of a unique coating. To prevent condensation and rusting, steam should not be admitted until workpiece surfaces are above 100 “C (210 “F). Air must be purged from the furnace before the temperature exceeds 425 “C (795 “F), to prevent the formation of a brown coating instead of the desired blue-black coating
Charcoal-Based
Atmospheres
These atmospheres (AGA classes 402 and 42 I ) are on the day to becoming obsolete. Their main use currently is by small manufacturing
Electric
Furnace
Co.
plants wanting a generator low in initial cost and for intermittent use. Principal uses today are in the manufacture of malleable iron castings and as atmospheres in small toolroom, heat treating furnaces.
Exothermic-Endothermic-Based
Atmospheres
These atmospheres (classes 501 and 502) are m-formed exothermicbased types and are less reducing than conventional endothermic-based atmospheres. Potentially. they can be substituted for exothermic, endothermic, and nitrogen-based atmospheres in virtually all applications for which any one of the three amlospheres is recommended. Also, they are used as carrier gas in carburizing and carbonitriding.
12 / Heat Treater’s Guide Equipment requirements for hardening small parts made of 1070 steel in cxothermic-endothermic atmospheres are provided in Table I?.
Atmospheres for Backfilling Quenching in Vacuum
and
Production
Backfilling with a cooling gas in a vacuum furnace speeds up the cooling rate. Other uses of backfilling include: suppressing the vaporization of oil in integral quench vacuum furnaces and providing an atmosphere for carburizing and nitriding. Inert gases, nitrogen, and hydrogen (rarely) are used for cooling; contaminants in cooling gases must be held to a minimum to maintain the surface intefity of workpieces and to avoid damage to furnace parts. Backfilling and forced circulation increase cooling rates. aid in hardening, and in some instances are used to anneal metal alloys. Cooling gas is usually introduced into a vacuum chamber at the end of the high temperature soaking period. Vacuum furnaces can be used for carburizing by the injection of any one of several atmospheres that induce carburizing at appropriate temperatures. Nitrogen enriched with a hydrocarbon gas is most frequently used. Carburizing is normally carried out in the range of 870 to 980 YI t 1600 to 1795 “F). ln the carburizing and diffusion process, surface carbon content of 1% or more is formed initially. The high-carbon case is then diffused in vacuum to the desired surface content and case depth.
Ion Carburizing
Atmospheres
A hydrocarbon gas that is ionized by a high voltage system in a vacuum is a suitable atmosphere for this process. Methane is frequently used. The process is faster than conventional atmosphere carburizing. and surface carbon content approaches saturation. For carbon control, other diluting gases are added. An AISI 1018 steel can be ion carburized to a depth of I .O mm (0.040 in.) with a IO min cycle in an atmosphere of methane at I .3 to 2.7 kPa ( IO to 30 torr) and a temperature of 1050 “C (1920 “F). Carburizing is followed by a 30 min diffusion cycle in vacuum at the same temperature. About 100 V is needed to produce the plasma.
Cold and Cryogenic
Table 12 Equipment Requirements for Hardening Small Parts Made of 1070 Steel in an ExothermicEndothermic Atmosphere
Treatment
Common practice for cold treatment is regarded to be -84 “C (-120 “F). In cryogenic treating. parts are chilled to approximately - 190 “C (-3 IO “F). Ref I. Benefits from cold treatment range from enhancing transfomiation from austenite to martensite to improving the stress relief of castings and machined parts. In each case, even greater gains are realized \ ia cryogenic treatment.
Cold Treating As a rule. I h for each inch of cross section is adequate. All hardened steels treated in this manner have less tendency to develop grinding cracks and grind easier after retained austenite and untempered martensite are eliminated-100% transformation to martensite in hardening is rare. Cold Treating vs. Tempering. The best opportunity for maximum transformation to martensite is to cold treat parts immediately after hardening (and before tempering) when parts cool down to room temperature, or at a temperature within the range for quenching. A caveat is attached to this procedure: cracking could result. For this reason, it is important to ensure that the grade of steel and product design will tolerate immediate cold treating. rather than immediate tempering. Some steels must be trans-
requirements
Number of parts per load Weigh1 of each part. kg I lb) AIa.\imum nel wright of load. kg(lh) Production rale. kg I lb) Equipment
2625 00069~0.015) 18(-K)) 7.5 loads ( 135. or 300) per h
requirements
Hardening furnace Size of hearth, m (ti) Heat input. H’/h I Btu/h) Operating Iempzrature. “C c”F) Capacir) of generator. nil/h (ft-l/hJ T> pe of atmosphere Capacih’ofoil-quench tank. Ltgal) lJprofoil,“C(“F) Tmmperarure ofoil. “C IOF) Oil agilation
Ion Nitriding
Gas-tired radiant-tube single-row pushertype \virh automatic quench 0.9 (3) wide by 2.9 (9%) long 2.2 x I oi HhKs (7.5 x 105) 900 i 1650) 68 (1400) Class so1 1250(330, Fas& I80 (360) flash point
70 ( 160) (controlled) ~ldhll
Atmospheres
The process is similar to that of ion carburizing. except that the atmosphere gas generates nitrogen ions. and the process is carried out at lower temperatures. Suitable sources for nitrogen ions are ammonia or mixtures of hydrogen and nitrogen. A typical cycle of 8 h at 5 IO “C (950 “F) with a mixture of 75% hydrogen and 2% njtrogen at a pressure of0.9 kPa (7 torr) and a current density of 0.8 mA/cm- will produce a nitrided case of 0.30 mm (0.012 in.) in AISI 4140 steel. About 400 V is needed to generate the plasma.
Reference I. XX
hler~~ls Hmdbook. Vol4.
10th ed. ASM International
of Steel ferred to a tempering furnace when they are still warm to the touch to minimize chances of cracking. Design features such as sharp comers and abrupt changes in section create stress concentrations and promote cracking. In most instances, cold treating does not precede tempering. Ln several applications, tempering is followed by deep freezing and retempering uithout delay. Such parts as gages and pistons are treated in this manner for dimensional stability. In critical applications, multiple freeze-temper cycles are used. In addition, in cases where retained austenite could result in excessive wear. the wear resistance for several different materials is improved, ie., tool steels; high-carbon. martensitic stainless steels, and carburized alloy steels (see adjoining table).
Process
Limitations
In some applications, explicit amounts of retained austenite are considered beneficial, and treatment could be detrimental. Also, multiple tempering, rather than alternate freeze-temper cycles, is generally more practical in transforming retained austenitc in high speed and high-carbon/highchromium steels.
Heat Treating Processes and Related Technology Hardness Testing. Lower than expected HRC values may indicate excessive following
retained austenite. Significant increases in hardness readings cold treatment indicate conversions from austenite to martensite. Precipitation-Hardening Steels. Specifications for these steels may include a mandatory deep freeze after solution treatment and prior to aging. Shrink Fits. This result can be obtained by cooling the inner member of a complex part. Care is advised to avoid brittle cracking when the inner member is made of heat treated steel containing large amounts of retained austenite, which converts to martensite in subzero cooling. Stress Relief. Cold treating is beneficial in stress relieving castings and machined parts of even or nonuniform cross section. Features of the treatment include: l
l
l
l
l l l
Transformation of all layers is accomplished when the material reaches -84 “C (-I 20 “F) The increase in volume of the outer martensite is somewhat counteracted by the initial contraction due to chilling Rewarm time is more easily controlled than cooling time, allowing equipment flexibility The expansion of the inner core due to transformation is somewhat balanced by the expansion of the outer shell The chilled parts are more easily handled The surface is unaffected by low temperature Parts that contain various alloying elements and that are of different sizes and weights can be chilled simultaneousI)
Advantages
/ 13
Wear Resistance as a Function of Cryogenic Soak Temperature for Five High-Carbon Steels Wear
reistance,
&(a) SOaked
Alloy
Untreated
52100
25.2
D2
22-l
A2 hl2 01
85.6 1961 237
-tLaT(-12oT) 19.3 308 174.9 2308 382
-l!mT(-31oT) 135 878 565 3993 996
(a) R, = R’AVH,. where Fis the normal force in newtons. N. pressing the surfaces together; \‘isthesliding velocib inmm/s; \\‘is theaearrate in mm’/s;and Hv is the Vickers hardness in MPa. R, is dimensionless. Source: Ref 3
Plot of temperature vs. time for the cryogenic treatment proc_ ess. Sour&
Ref 2
of Cold Treating
Success depends only on reaching the minimum low temperature, and there is no penalty for a lower temperature. As long as -80 “C t,- I IS “F) is reached transformation takes place. Reversal is not caused by additional chilling. Also. materials with different compositions and different configurations can be chilled at the same time. even though each may have a different high temperature transformation point.
Cryogenic
Treatment
A typical treatment consists of a slow cool-down rate (25 “C/min equivalent to 3.5 “F/min) from ambient temperature to the temperature of liquid nitrogen. When the material reaches approximately 80 K (-3 IS “F). it is soaked for an appropriate time (generally 24 h). Then the part is removed from the liquid nitrogen and allowed to warm to room temperature in ambient air. The temperature-time plot for this treatment is shown in the adjoining Figure. By using gaseous nitrogen in the cool-down cycle. temperatures can be controlled accurately. to avoid thermal shock. Single cycle tempering usually is the next step-to improve impact resistance, although double or triple tempering cycles are sometimes used for the same reason.
Kinetics
of Cryogenic
Treatment
According to one theory with this treatment, transformation of retained austenite is nearly complete-a conclusion that has been verilied by x-m> diffraction measurements. Another theorq is based on strengthening a
Representative
Applications
Pit Furnaces
Normalizing Stress relieving
References I. ,&SM &m/s Hmdhook. Heat Treating, Vol 3. 10th ed., ASM Lntemational 2. R.F. Barron and R.H. Thompson, Effect of Cryogenic Treatment on Corrosion Resistance, in Adwnces in C~ogenic Engineering, Vol 36, Plenum Press. 1990. p I375 I379 3. R.F. Barron, “How Cryogenic Treatment Controls Wear,” 2lst InterPlant Tool and Gage Conference. Western Electric Company, Shreveport, LA, 1982
of Heat
Representative applications of 36 different types of heat treating furnaces, reported by suppliers of equipment. are listed in this section. Ref I
Soaking
material via the precipitation of submicroscopic carbides. An added benefit is said to be a reduction in internal stresses in the martensite developed during carbide precipitation. Lo\\er interior stresses may also reduce tendencies to microcrack.
Treating
Furnaces
Reheating
Batch or In-and-Out Normalizing Annealing Aging
Furnaces
14 / Heat Treater’s Guide Carburizing (diffusion Stress relieving
Normalizing Carburizing Nitrocarburizing Carbonitriding AMeding Carbon restoration Stress relieving Austenitizing
phase)
Box Furnaces Annealing Tempering Hardening Normalizing Stress relieving Aging Carburizing Malleabilizing Solution heat treating
Carbon
Bottom
Tip-Up
Annealing, i.e., wire, long bars, rods, pipe Hardening Spheroidizing Normalizing Malleabilizing Tempering Stress relieving
Furnaces
Annealing, i.e., coatings Hardening Normalizing Malleabilizing Stress relieving Carburizing Tempering Spheroidiiing Homogenizing
Wraparound
Vertical
Annealing, including long cycle annealing Hardening Tempering Normalizing Stress relieving Steam treating Homogenizing Carburizing Carbonitrid’mg Carbon restoration Bluing Nitriding Solution heat treating
Bell and Hood Furnaces Hardening Nitriding Aging Bluing Tempering Stress relieving Solution heat treating
Hearth
Quench
Case hardening Neutral hardening Clean hardening
of ferrous parts
Furnaces
Continuous
Slab and Billet
Solution heat treating Homogenizing Carbunzing
Walking
Beam Furnaces
Hardening Annealing Tempering Stress relieving Normalizing Sintering stainless steel compacts
Hearth
Furnaces
Hardening Annealing Carburizing Carbonitriding Carbon restoration Malleabilizing Tempering Austempering
Pusher Furnaces
Furnaces
Annealing Hardening Normalizing Malleabilizing Tempering Stress relieving Austempering Carburizing
Rotary
Solution heat treating Hardening Aging Malleabilizing Tempering Annealing Stress relieving Lab work
Integral
and Split Furnaces
Annealing Stress relieving
Pit Furnaces
Elevating
Furnaces
Furnaces
Annealing Carbonitriding Carburizing Hardening Normalizing Clean hardening
Heating
Furnaces
Heat Treating Processes and Related Technology
Screw Conveyor
Ferritic nitrocarburizing Malleabiliziig Solution heat treating Tempering Stress relieving Carbon restoration Spheroidizing
Furnaces
Hardening Tempering Annealing Stress relieving
Slotted Roof, Monorail Roller Hearth Furnaces
Nitriding. i.e.. extrusions Carburizing steel parts
Hearth Furnaces
cover gas
Rotary Hearth Furnaces Small ferrous parts Process and production testing Small volume production Hardening Tempering Austempering Anneahg Carburizing Carbon restoration Carbonitriding
chains. and other long and
Furnaces
and D? tool steels
Annealing. i.e.. bright annealing Hardening Tempering Stress relieving Cnrburizing Carbonitriding Depassinp Carbon deposition
Bed Furnaces
Nitrocarburizing Nitriding Carbonitriding Steam oxidizing Carburizing Hardening. bright type Tempering
Salt Bath Pot Furnaces
Shaker Hearth Furnaces Hardening, i.e.. neutral hardening Carburizinp Carbonittiding Stress relieving Normalizing Anneding Tempering Austempering
Furnaces
Vacuum Furnaces
Fluidized
Furnaces
Applications requiring hydrogen Heat treating stainless steel Annealing Stress relieving Carburizing Hardening
crankshafts.
Ion NitridingKarburizing
Tempering Hardening, i.e.. clean hardening Carbon restoration Annealing, i.e.. bright annealing Carbonitriding Austempering Carburizing Spheroidizing Homogenizing
Humpback
Conveyor
Annealing. i.e.. large castings, unusually shaped parts Hardening Tempering Annealing Normalizing Stress relieving
Solution heat treating Stress relieving Bluing Spheroidizing Tempering Nomutlizing Malleabilizing Hardening, i.e., clean hardening Tempering Carburizinp Carbonitriding Carbon restoration
Conveyor
/ 15
carbon steel and light case hardenmg
Austempering Martempering Hardemng Tempering Carburizing Cyaniding
Salt Bath Furnaces: Austempering. i.e.. ductile Carburizing Carbonitriding Nitrocarburizinp Nomtalizing Neutral hardening
Salt Bath Furnaces:
Austemper
Batch Austemper iron. steel
Mesh Belt
System
Austempering. i.e.. ductile Carboaustempenng steel
iron. steel
System
16 / Heat Treater’s Guide Neutral
Salt Based Furnaces
Quartz Tube Furnaces
Austempering Martempering Hardening
Cyanide
Sintering Heat treating
Rotating
Based Salt Type Furnaces
Furnaces
Heat treating, continuous long lengths of pipe, turbine, bars, rods, billets Included in quench and temper lines for high grades ofoil country tubing
Cloverleaf
Induction
Furnaces
primarily.
Treating
hardenable
Heating
types
Systems
Aging Stress relieving Hardening Annealing. i.e., bright annealing Carbonitriding Normalizing
Equipment
i.e., martensitically
Systems
i.e.. surface and localized
Resistance
Beam Surface
Surface hardening metals
Heat Treating
Hardening, Tempering
Hardening Normalizing Tempering Carburizing Annealing Carbonitriding Carbon restoration
Electron
Furnaces
Hardening Normalizing Tempering Annealing Stress relieving
Carburizing Case Hardening
Barrel
Finger
ferrous
Reference
Laser Heat Treating
Furnaces
I. Joseph H. Cireenberg, lndrtstrial Tirenml Processing Equipment Handbook, ASM International, 199-I
Annealing
Statistical
Process
Control
of Heat
Statistical process control (SPC) is being applied to advantage in heat treating shops with continuous, hatch, and single part operations. (A case history of how one shop has integrated this technology into its operations is reported in a sidebar feature to this article. In many instances. as in this one, teaming SPC with the computer is the next step). Ref I. Continuous equipment, such as rotary retorts, pusher carburizers, and belt furnaces, offer the most straightforuard approach to applying both statistical quality control (SQC) and SPC techniques to improle process performance. The high volume of work handled by continuous equipment provides many opportunities for sampling key product characteristics.
Treating
Operations
Problems can be predicted and corrective action taken in a timely manner. Also, special causes of prohlems are often more identifiable because process variables are steadier in continuous processes than they are in batch operations. Batch operations alloh a significant amount of sampling and analysis within a load. However, the only net payoff is a degree of confidence in treating an entire load. Process vmables must be monitored and analyzed to ensure that the process is under control, and that there is load-to-load and day-to-day repeatabilit~-especiall~ when each load is different in terms of part geometry. matenal. and/or specification.
Contribution of Selected Parameters to Variations in Effective Case Depth for Required 0.85 to 1.OO%Surface Carbon Level at 870 “C (1600 “F) Processing Temperature Variation Case depth mm in.
OS1 I .O? I .52 2.03
0.020 0.040 0.060
0.080
Temperature variation 28 T 11°C
(2OW 6 6 7 9
(AT) 56 =‘C
(50OF) (1~W I-l 16 17 19
33 34 35 36
in case depth for selected parameters,
Timevariation Smin 10 min 3 1 >I >I
7 ‘) ;
>I
(A I ) 30 min 30 5 2
I
0.10%
a a a a
Atmosphere 0.15% 13 13 13 13
%(a) Carbon 0.25% 27 27 17 27
tariatioo
(AC ) Quench uniformity(b) 0.05% 0.10% 0.20% I1 II
II II
23 23 23 23
45 45 45 45
(a) Total process variation = dA2+ B’ + C’ + D’ + Z-‘, where r\. B. C, D, and Zare ‘7%variations attributed 10AT. .I 1.aunosphere X. quench uniformity AC, and additional vtiahles. respectively (b) Variation in case c&on level u hen quenched to SOHRC
Heat Treater’s
Guide: Practices
and Procedures
for Irons and Steels
Copyright@ ASM International@ 1995
Heat Treating Processes and Related Technology / 17
Final hardness
Identification
distribution
of heat-treating
analysis
for a typical
variables
quench
for the neutral
and temper
hardening
operation
process
18 / Heat Treater’s
Guide
Variation in natural gas composition
monitored in the Canton, OH, area over nearly a 2l&year period
Plot of furnace temperature versus elapsed time to show that heat input equilibrium lags behind attaining of setpoint temperature after furnace loading
Plot of furnace temperature versus elapsed time to show effect of load size on heat balance equilibrium
Single part treatment, as with induction or flame treating, does not lend itself to using part evaluation techniques to predict negative results. The focus must be shifted to SPC and to the identification, monitoring, and control of process variables to ensure repeatability of results. Some variables that need to be considered are electrical power, flame temperature, scan speed, coil dimension, part positioning, and quenchant temperature. Trending of process variables can be utilized to determine special causes. Process deterioration is another factor that must also be taken into account in all types of heat treating operations. The challenge is to counter wear and tear on equipment with corrective action before out-of-specification parts are produced. Key process variables fall into three categories: those which ;LTecontrollable, those which aren’t, and those which are secondary. Controllable variables include temperature, atmosphere carbon potential. and quenchant temperature.
Uncontrollable variables include quench transfer time, temperature recovery time, and quench temperature rise. However, suitable courses of action are available. Examples follow: l
l
l
With most furnace systems. control of quench transfer time is not possible, but is often a critical parameter in producing good parts. A possible course of action is to monitor and analyze transfer time to get an early warning of trouble. One automatic control system compares maximum allowable transfer time needed to get the desired result with actual transfer times; an alarm is triggered when the maximum is exceeded, indicating a mechanical failure or deterioration in the system. Temperature recovery time can be determined, for instance, by measuring and analyzing the time taken by a batch furnace (with a standard load weight or empty) to reach set temperature. In this manner, trends, plotted
Heat Treating Processes and Related Technology / 19
Calculated CCT diagram from actual part composition to form during
l
heating.
Ac3: temperature
at which
with modeled part cooling rates. AC,: temperature
transformation
of ferrite
on an WC chart, may indicate a loss in furnace performance which, via investigation, could be traceable to damaged insulation, poor door seals, or heating system malfunction, for example. Knowing how quench temperature cycles from quench to quench can be important. Findings may trigger an investigation of the entire quenching system, which may suggest problems with quench agitation or quench cooling, for example. Furnace overloading is another possibility.
Secondary process variables, such as fuel consumption and additive atmosphere gas, are caused by deterioration in control loops. By monitoring gas or electrical consumption for a standardized furnace cycle and loading (or the furnace could be empty), diminished performance in the heating system can be detected. By monitoring and trending the amount of natural gas or propane addition required to control a given carbon potential setpoint, deterioration of furnace atmosphere integrity can be detected. Examples of parameters with an influence on effective case depth are given in an adjoining Table. A variable distribution analysis of hardness of a job is shown in an adjoining Figure. Heat treating variables involved in neutral hardening are given in an adjoining Figure. Changes in natural gas composition over an extended period are plotted in an adjoining Figure. How heat input equilibrium lags setpoint temperature after a furnace is loaded is shown in an adjoining Figure.
to austenite
is completed
during
at which heating
Effect of load size on heat balance equilibrium ing Figure.
Integrating
austenite
is indicated
begins
in an adjoin-
SPC and SQC
Potentials for real time process improvement can be realized by combining the disciplines of SPC. which focus on process variables, and SQC. which focus on product quality. The computer is needed to statistically analyze data in a way that allows timely adjustment of process. As a product characteristic (as-quenched hardness, for example) is shown to be trending away from average, a special cause, such as quench temperature. may be identified quickly. Ability to compare process variable trend charts to the product characteristic trend chart, for the same time period, offers a valuable tool for continuing improvement. Information can be valuable even if no special cause can be. identified among monitored process variables to correlate with a change in product quality. Such knowledge could lead the heat treater to an uncontrollable variable, such as material, more quickly than he could otherwise. An example of hou the computer is being utilized is shown in an adjoining Figure.
Reference I. Memls Hmcfbook. IO ed. Vol3.
Heat Treating,
ASM International
20 / Heat Treater’s
Guide
How a Commercial
Heat l’kater
This shop decided in 1989 to look into statistical processcontrol (SPC) as a way to track down sources of persistent processing problems. At the time. rework jobs (in carburizing and nitriding) were running at a rate of 25 to 30 per quarter. Ref 1. Consultants were hired to train the plant’s thirty-plus employees in the application of WC lo heat treating. how to recognize out-ofcontrol conditions. and how lo react correctly lo them. Training was thorough. but stopped short of teaching how-to-be statisticians. The program consisted of I2 h in the classroom(three 4 h sessions),plus followups on the shop floor lo answer questions as WC was being installed. The key to making SPC work, it was stressedcontinuously, is accuracy of data. At the same time. employees were assuredthat these data would be used as spotlight opportunities for impmvemen¬ to point the finger of blame at anyone.
The First Step The program was started by gathering data from carburizing furnaces.using simple SPC charts.Operatorsuseda shim shock test
9n early control chart shows large variations, with a low Drocess capability caused by poor understanding of Jariables
Uses SPC and the Computer to compare actual carbon in the working zone compared with the level set on the furnace controller and measuredwith an oxygen pl-0bl.L Resultsfell short of expectations-a typical chart from that period is shown in an adjoining Figure. Note the largediscrepancybetween oxygen probe and shim shock data. A seriesof meetings followed. which included the quality manager,production manager,and all shop employees.In addition. furnace operators.maintenancepeople, and all other employeeswere encouraged to submit suggestions for improvements. Ultimately. a decision was made to do capability studies of all carburizing and nitriding furnaces in the shop. covering, for instance,natural gas flow, air flow, nitrogen/methanol flow, load size, time in furnace. carbon control instrument settings,methodsoperators used lo run furnacesand to correct out-of-control conditions. Much of the inconsistency in performance, it was learned. was accountedfor by differences in practice from operator lo operator. To improve control here,procedureswere written, basedon proven strategiesfor correcting out-of-control conditions.
The same furnace, eight months later, remains within control limits of kO.O7% C
Heat Treating
With time, operators managedto keep data points closer to the target mean (for carbon potential setpoint), and control limits were set at ?0.07%. Improvement in the performance(seeprevious Figure) over a period of eight months is shown in the secondFigurenote that control limits were maintained within 0.07%. By 1992, reworks were down by a factor of four (see Figure). Reasonsfor rework, along with percentagesattrihutahle for each cause, are shown in the next Figure. Shallow case depth was the most common causefor rework, with a 23.3% rating. CauseNo. 2 was operator error, accounting for 20% of all rework. For each rework. the company evaluates findings, investigates, and corrects any areasof concern.
Statistical
Methods
The company now tracks performanceby processcapability values, C, and Cpk (see Figure for definitions of theseand other SPC terms). Information collected by operatorsis loadedinto a statistical program, which producesall values neededfor review by management.
Tighter
Shallow
control
and more-predictable
case depth and operator
process
results
and Related Technology
A processcapability study of furnace number 37 for one month is shown in an adjoining Figure. The Cpk is I.41 and the process capability index (C,) is I S2, showing that the natural variation in the process is less than the maximum acceptable range for the product. One year earlier, this furnace had a Cpkvalue of 0.55 and a C, value of 0.63. The company performs a Paretoanalysis (seeprevious Figure for definition) for all rework. Reasonsfor rework, the furnace. and the operatorsare recorded.
The Next Step The company has computerized all carburizers and oil hardening furnaces with atmosphereand temperaturecontrollers. With these controllers, furnace operation and tinal results are much more consistent than before. Controllers are also programmable. Operators simply input the correct program number to control all parametersrelated IO the carburizing cycle, ensuring that all temperatureand carbonpotential
have reduced
error were the most common
Processes
the number of reworks
reasons
for
reWOrk
in
1992
required
(30
reWOrkS
by a factor of four
total)
/ 21
22 / Heat Treater’s
Guide
SPC Terminology Mean, x: The central value in the range of processvariables, also known as the average.It is calculated by adding all readings and dividing by the total number of readings. Standarddeviation, O: A measureof the spreadof data values that is, the how far the data varies from the mean. It is calculated by the formula
whereXi is the valueof datapoint numberi. Zis the mean,andn is the total numberof datapoints. Control limits: Upper and lower control limits are defined as three times the standarddeviation (30) from the mean (X ) of a processvariahle.Statistically.99% ofreadingsshouldfallwithin thesecontrollimits.unlessthereisachangeintheprocess. Control chart: A graph used to record the readings of process variables. Each point in an x chart is typically an averageof four or more readings. Each point in an R chart is the difference
betweenthe highest and lowest readings(range).Trendsin control chart data can be signs of trouble. Examples include a point outside the control limits. sevenconsecutivepoints drifting in the samedirection, or fewer than two-thirds of the points within the middle third of the chart. Natural variation: Processvariable fluctuations that are beyond the control of the operator. The only way to reduce the amount of natural variation is to improve the process. Pareto analysis: A process used to identify what J.M. Juran talk the “vital few projects” for which quality improvement is justified; that is. those which contain the bulk of the opportunity for improvement. Named for Italian economist Vilfredo Pareto (1848-1923). Process capability index, C,,: The product specification or tolerance range divided by six times the standarddeviation. Cp indicates whether the process is able to meet the customer’s requirements.A value lessthan one indicates that natural variation will produce results that are out of spec. Actual Process Capability Index, Cpk: A stricter index than C, Cpk measurescentering as well as the amount of natural variation. It is defined asthe difference betweenthe processmean and its closest specification limit, divided by 30.
Heat Treating
Practical
Applications
of the Computer
A quick overview of available simulation software for on-line programs that control processes and those that assist in decision-making and process analysis is provided by the adjoining Table, which also lists and describes available databases developed by computers. Software programs can be subdivided as follows: l l l l
l
Property prediction programs Process planning programs Material selection programs and their databases Programs for special technical and economic programs related to heattreating, such as energy consumption for a given process or calculating the expense of a heat treatment Finite element analysis for modeling the effecti of quench severity or distortion and dimensional control of parts Simulation modeling with the computer can be subdivided thusly:
l
Static models based on empirical formulas
l
l
Processes
in Heat
and Related Technology
/ 23
Treating
Dynamic models based on differential equations or differential equation systems Programs with both static and dynamic models
Static models are based on simple empirical formulas that can be derived by physical principles and observation or from statistical methods. Generally, regression analysis is used in statistical modeling. Example: Formulation or prediction of Jominy hardenability from austenitic grain size and chemical composition (Ref l-3). Dynamic models are based on the solution of differential equations, differential equation systems, or finite element analysis. Examples of the differential equation approach: predicting carbon and nitrogen profiles (Ref 4-6) phenomenological models that describe the transformation of austenite under nonisothermal conditions (Ref 7-l I). Finite element analysis is used, for example, to predict residual stress and distortion (Ref 12-14) and in determining suitable quenchants (gas, oil, or water) for a given alloy (Ref 12).
24 / Heat Treater’s Guide Examples of Available Computer Programs and Databases Pertaining to Steel Selection, Microstructure, and Heat-Treatment Technologies
Computerized hlat.DB
Features
Availability
Name of the sofhvare materials
properties storage, retrieval, AShl lntemational. U.S.A.
and use
Database Steelhiaster
PERlTUS
A LlETA
SACfTSteel Advisory Centre for Industrial Technologies, Hungary
KOR
SACfTSteel Ad\ isory Cenue for Jndustrtal Tu-hnologies. Hungary
Computer
programs
Materials data base management program containing the designations, chemical compositions, forms (sheet bar and so forth), and properties t up to -MI properties). It is designed to select alJoys on the basis of many characteristics Contains the chemical compositions. meshanicaJ properties, application fields, and the international comparison tequiv alent steels) of 6500 standard steels from I8 countries Contains compositions, mechanical properties. heat-treatment parameters, CCTdiagrams. tempering charts for commonly used German structural and tool steels The heat-neaanent technologies designed by the user of the softwate can be stored and retrieved This data hase pro\ ides engineers uith up-to-date information about materials ranging from traditional met& to new polvmers. The range of information: mechanical and physical properties, environmental r&istance. material forms. processing methods, trade names, and standan% This data base of individual measured steel properties contains data collected from laboratories of industry quality control departments. The range ofdata: steel designation, heat number, dimensions of the machine part. composition, heat treatment of the part, results of tensile tests, impact test results, measured Jominy curve of the heat, and other tests. The system makes statistical analysis of the data KOR is a corrosion information system. which contains a data base of 3OOcorrosive media, more than IS 000 individual corrosion dataset I50 metallic structural materials. and 200 isocorrosion diagrams. Structural material selection is possible according to prescribed mechanicrd. physical, technological properties. or it is possible to find a suitable resisting material fora corrosive medium withgtven temperatureandconcentratJon.The system #ill alsoaccept the user’sowndata
SACIT Ste4 Advisory Cenae for Industrial Technologies, Hungary Dr. F?Sommer Wkrkstoftiechnik GmbH. Germany hlatsel Systems Ltd., Great Britain
EQUJST 2.0
for calculation
of processes
occurring
in steels during
PRJZDIC & TECH
SACIT Steel Ad\ isory Centte for industrial Technologies. Hungary
AC3
Marathon
CETfM-SICLOP
PREVERT
Cenue Technique des Industries Mechaniques PROGETfM. France Comline Engineering Software, Great Britain and ASM International Creusot-Loire Industries. France
CHAT
lntemational
hlfNlTECH
hlinitech
PRJZDCARB
SACfTSteel Advisory Centm for Industrial Twhnologies. Hungary
SINULAN
Lammar.
Ensam Bordeaux.
C4RBCALC
Marathon
hlonitors
CARBODIFF
Process Electronic.
Carbo-O-Proof
lpsen Industries Ltd.. U.S.A.
SYSM’ELD
Framasoft.
SteCal
Examples
of programs
Monitors
Limited.
Company.
Calculates the micmsmtcture and mechanical properties ofquenched and tempered low-alloy steels from composition and heat-treating parameters CHAT is a two-part system for selecting the optimum steel composition to be used where heat treating is perfomted to develop required engineering pmperties The hlinitech Alloy Steel Information System consists of tvvelve computer programs which generate a series of hardenability-related properties of steels. such as Jominy curves. hardenahility bands, mechanical properties of hot rolled products. hardness distributions for quenched and tempered and carburized products This computer program detemunes the gas carburizing technology and calculates the carbon profile and hardness distribution in the case and core on the basis of chemical composition, dimensions of the workpiece. cooling intensity of the quenchant, prescribed characteristics of the case Simulates the gas carburization and inductton hardenmg process. and calculates the carbon and the hardness profile Smtulates the carburirmg reactions between a steel and surrounding atmosphere. It calculates the carbon profile hlonitoring of carbon protile dunng carburizing and prediction of hardness distribution after quenching ofcase-hardened steels This software is able to optimize the carburizing process, calculates continuously the carbon profile, and regulates the process in accordance \v ith program target values This system is based on finite-element technique and simulates the transformation processes in steel during heat treatment or welding. The program calculates the temperaturedistribution. microsnucture, hardness. and stresses
U.S..\.
Canada
France
Ltd.. Great Britain Gemtatty
Great Britain
based on finite
element
analysis
heat treatment
Stmulates the cooling. transfomtation of austenite in cylindrical. plate-shaped workpieces, Jominy specimens made of case-hardenable and quenched and temprrcd low-alloy steels and calculates the microstructure and mechanical properties in any location of the LTOSSsection of the workpiece taking into account the actual chemical composition, dimensions. austenitizing temperature, duntions, cooling intensity of quenchant, tempering temperature. and time. The same program worksas technology plannmg program if the prescribed mechanical properties and composition are given Hardenability model designed to predict the response to quenching of through-hardening and carburized loa -ahoy steels in terms of microstructure and hardness distribution Contains a steel data base for the selection of structural and tool steels and calculates the mechanical properties along the cross section of \5 orkpieces Calculates the heat-treatment response and properties of lo\\-alloy steels from composition
Ltd.. Great Britain
Harvester
include:
tinuous
cooling
H ith the results l
CONTA
program-for
l
TOPAZ
2D program-for
calculating
l
NIKE
2D program-for
surface
calculating cttkulating
heat fluxes
temperatures stresses
overviews
of the subject
Database systems metal alloys them include
are being chemical
containing marketed. composition,
are found
(Ref
(Ref
(Ref
State of the Art Uses of Computer General
Properties,
13)
I-%)
ISj
Simulation
in Ref
I6 and
17.
the main characteristics of several lnfomtation that can be retrieved front mechanical characteristics. and con-
transformation
(CCT)
of user process
planning.
curves.
Databases
can
be loaded
Example: Research Ltorkers at hlinitech Ltd (Canada) designed a soliware package to estimate such properties as weldability. phase diagrams, and hardenability of low-. medium-, and high-carbon steels (Ref 16). Example: Chrysler Corporation developed an interactive system that makes it possible for designers and technologists to get material information on their own local computer terminals (Ref 16). Example: Utilization of databases of measured steel properties is discussed in Ref 18. The CETIM Institute (France) has developed a program for the planning of heat rrcatment technology and for steel selection. An essential part of the
Heat Treating Processes and Related Technology software is a database containing chemical composition, mechanical properties, and Jominy curves of the most often used quenched and tempered and case hardened steels as a function of section size (Ref 19). Hardenability prediction has been of longstanding theoretical and practical interest (Ref 20-24). In applying a static model, Murry et al. (Ref 25) developed a computing method for predicting the hardness of cylindrical workpieces along their cross section after quenching. Input data are: chemical composition. austenite grain size, geometrical characteristics, and cooling time from 700 to 400 “C ( 1290 to 750 “F). Creusot-Loire (Ref I6 and 26) used nonlinear multiple regression analysis to derive a series of formulas for the estimation of critical cooling rates from 700 “C ( I290 “F). The steelmaker aJso published equations to calculate as-quenched and tempered hardness from chemical composition and cooling rate from 700 “C ( 1290 “F). Starting from a thermodynamic basis, researchers at McMaster Llnivershy (Hamilton, Ontario, Canada) developed methods for the computeraided determination of equilibrium diagrams of multicomponent steel alloys and for the calculation of starting curves (incubation time) of isothemtal transformation diagrams as well (Ref 17. 23, 37). They also investigated the tempering process and developed usable computer programs for the prediction of hardenability and its application in steelmaking.
Programs for material selection and/or analysis of heat treatment processes usually contain a system for property or hardenabilit! prediction. Liscic and Ftletin (Ref 21. 22). for example, published a computerized process designing a system for the heat treatment of quenched and tempered steels. The system is suitable for the determination of technological parameters (austenitization and tempering temperatures), knowing the steel type and required properties. More sophisticated models based on finite element analysis are being investigated as a way of modeling distortion and analyzing quenching methods (Ref 12). Analysis of residual stresses and distortion generally in\ elves finite element anaJysis of internal stresses developed during transformation sequences. Typical examples are given in Ref I?, 28-30. A method of calculating transformation sequences in quenched steels is found in Ref41. A software package has been developed for the prediction of residual stresses in case hardened steels by tracing the transformation of the case and core of the workpiece (Ref 32 and 43). Simulation of Case Hardening. New type models predict carbon and nitrogen profiles during and after gas carburizing and nitriding t Ref 5. 6.28-31). In this field, calculation methods can be used to model case depth and hardness proftles (Ref 30, 35. 36). lngham and Clarke developed a computerized method of predicting the microstructure and hardness profile of case hardened parts. Methods of microstructure prediction are described in Ref 8 and 37. A description of how a commercial heat treater is using SQC. SPC. and Process Control in Heat the computer is found in the article. “Statistical Treating Operations,” preceding this one. This article is based on article, “Computerized Properties Prediction and Technology Planning in Heat Treatment of Steel,” AShl hietals Handbook, Heat Treating, Vol 4. IO ed.. Hear Treatirrg Handbook. ASM International.
References I. C.A. Siebert, D.V. Doane. and D.H. Breen. The Hurdetu~biliy of.Sireels-
Cor~cep~s.Memlhrrgical Itljluences and Indrrsrrial Applicarions, American Society for Metals. I977 2. E. Just, Formeln der Hartbarkeit, Hiin.-Tech. Min., Vol23 (No. 2). 1968. p 85-99 3. E. Just, New Formulas for Calculating Hardenability Curves, Mer. Prog.. NW 1969, p 87-88 4. J. Slycke. T. Ericsson, and P Sjoblom. Calculation ofcarbon and Nitrogen Profues in Carburizing and Carbonitriding. Corrzpwers iu Marerials Technology, Proceedings of the International Conference. Linkoping Llnivershy. 4-S June 1980. T. Ericsson. ed.. Pergamon Press. p 69-79
/ 25
5. EA. StiU and H.C. Child, Predicting Carburizing Data. Hear. Treat. Met.. No. 3, 1978. p 67-72 Carburizing Process, Mefull. 6. CA. Stickcls, Analytical Models for the GZLS Trans. B., Vol30B, Aug 1989. p 535-546 7. T. R&i. G. Bobok, and M. Gergely, “Computing Method for Nonisothernlal Heat Treatments.” Paper presented at Heat Treatment ‘8 I, The Metals Society, 1983, p 91-96 8. E. Ftiredi and M. Gergely, A Phenomenological Description of the Austenite-Martensite Transformation in Case-Hardened Steels, Pmceedings of lhe 3rh Ituernarional Congwss on Hear Treamwtrr of Materials, Vol I, 3-7 June 1985. p 291-301 9. T. R&i. hl. Gergely. and P. Tardy, hlathematical Treatment of Non-isothermal Transformations. Aluclrer:Sci. Technol.. Vol 3, May 1987, p 365-371 IO. E.B. Hawbolt. B. Chau. and J.K. Brimacombc, Kineticof Austenite-Pearlitc Transformations in a 1025 Carbon Steel, Melall. Trans. A, Vol l6A. April 1985. p 568-578 I I S. Denis. S. Sjosuiim. and A. Simon. Coupled Temperature, Stress, Phase Transformation Calculation Model: Numerical Jllustration of the Internal Stresses Evolution during Cooling of a Eutectoid Carbon Steel Cylinder, h~lemll. Trans. A, VOI l8A, July 1987, p I203- I2 I2 I2 R.A. Wallis et al., Application of Process hlodeling to Heat Treatment of Superalloys. /rid. Hear.. Vol 55 (No. I). Jan 1988, p 30-33 13. J.V. Beck. “Users Manual for CONTA: Program for Calculating Surface Heat Fluxes from Transient Temperatures inside Solids.” Report SAND83-7 131. Sandia National Laboratories, Dee 1983 I-2. A.B. Shapiro. ‘TQPAZZD: A Tvvo-Dimensional Finite Element Code for Heat Transfer Analysis. Electrostatic and Magnetostatic Problems,” Report LJCJD-20824. Lawrence Livemtore National Laboratory, July 1986 IS. J.O. Hallquist. “NlKE2D: A Vectorized, Implicit, Finite Dcfomtation. Finite Element Code for Analyzing the Static and Dynamic Response of 2-D Solids.” Report LJCJD- 19677. rev. I, Lawrence Livermore National Laboratory, Dee I986 16. D.V. Deane and J.S. Kirkaldy, ed.. Hardenabiliry Concepts with Applications ro Sled. Symposium proceedings, 24-26 Ott 1977, American Society for hletals. p 493-606 17. T. Ericsson, Ed.. Conrpurers in Materials Technolog?: Proceedings of the International Conference. 4-S June 1980, Linkoping University, Pergamon Press, p 3-68 18. hl. Gergely, T. Reti. G. Bobok. and S. Somogy i. “Lltihzation of Databases of Measured Steel Properties and of Heat Treatment Technologies in Practice,” Paper presented at hlatcrials ‘87, The Metals Society, I l-14 May 1987 19. C. Lebreton and C. Tout-trier. CETlM-SICLOP: Un nouvel outil logiciel pour le tmitment themtique. Traif. 77rrrrn.. No. 308.1987. p l-8 (in French) 20. hl.E. Dakins. C.E. Bates, and G.E. Totten. Calculation of the Grossmann Hardenability Factor from Quenchant Cooling Curves, Memlhtrgic~, Furnace supplement. Dee 1989. p 7 2 I. B. Liscic and T. Fiietin, Computer-Aided Evaluation of Quenching Jntensity and Prediction of Hardness Distribution. J. Hear Trear.. Vol 5 (No. 2). 1988. p 115-124 32. B. List+ ,and T. Fiietin, Computer-Aided Determination of the Process Parameters for Hardening and Tempering Structural Steels. Hear Treur. hder.. No. 3. 1987. p 62-66 23. J.S. Kirkaldy, G.O. Pazionis. and SE. Feldman, “An Accurate Predictor for the Jominy Hardenability of Low-AUoy Hypoeutectoid Steels,” Paper presented at Heat Treatment ‘76. The hletals Society. 1976 2-t. hl. Umemoto, N. Komatsubara, and I. Tamura Prediction of Hardenability Effects from lsothemtlll Transfomtation Kinetics, ./. Hear Trrrrr, Vol I (No. 3). 1980. p 57-6-l 25. G. blurry. hl&hode Quantitative d’ Appreciation de la Trempabihte des Aciers: Esemples d’ Application. R~I: Mc~~ull..Vol 12. 197-l. p 873-895 (in French) 26. l? hlaynier. Le Pretert: hlodcl dr: Prevision des Charncteristiques hlechaniques des Aciers, Ir,,ri/. Tltentt.. Vol223. 1988. p 55-62 (in French) 27. J.S. Kirkaldv and R.C. Sharma. A New Phenomenology for Steel IT and CCT Cun es. Scr: MeraIl.. \;bl 16. 1982. p I I93- I 198
26 / Heat Treater’s Guide 28. M. Gergely
29.
30.
3 I.
32.
33.
34.
35.
36.
and T R&i. Application of a Computerized Information System for the Selection of Steels and Their Heat Treatment Technologies, J. Hear Tmat., Vol5 (No. 2). 1988.~ 125-140 T. R&i, M. RCger, and M. Gergely, Computer Prediction of Process Parameters of Two-Stage Gas Carburizing, J. Hear Treat., Vol8, 1990, p 55-61 U. Wyss, Kohlenstoff und Hglrteverlauf in der Einsatzb&tungsschicht-verschiedenen legierter Einsatzhlihle, Htirr. -7kh. Mirt.. Vol43 (No. I ), 1988, p 27-35 (in German) T. R&i and M. Cseh. Vereinfachtes mathematisches Model fiir awistugige Autlcohlungsverfahren. H&f.-Tech. Min., Vol42 (No. 3). 1987, p 139-146 (in German) J. Wiinning, Schichtwachstum bei S~ttigungs- und Gleichgewichtsaulkohlung-sverfahren, H&.-Tech. Mu.. Vol 39 (No. 2). 1984, p 50-54 (in -) B. Edenhofer and H. ffau. Self-Adaptive Carbon Pmfik Regulation in Carburizing, Proceedings of the 6th International Congress on Heat Treatment of Materials, 28-30 Sept 1988. p 85-88 D.W. lngham and PC. Clarke, Carburize Case Hardening: Computer Prediction ofStructure and Hardness Distribution, Hear Treat. Met., Vol IO (No. 4). 1983, p 91-98 N.F. Smith Computer Prediction of Carbtuized Case Depth: Some New Factors lnlluencing Accuracy of Practical Results, Heat Treat. Met., No. I, 1983. p 27-29 D. Roempler and K.H. Weissohn. Kohlenstoff und Hglrteverlauf in der Eiiaehslrtungsschicht-Zusatzmodul fk Dilkionsrechner, Hiin.-Tech.
Min. Vol44,1989, p 360-365 (in German) 37. M. Gergely, T. R&i, P Tardy, and G. Buzz. “Prediction of Transformation Chamctaistics and Microstructure of Case Hardened Engineering Components,” Paper presented at Heat Treatment ‘84. 24 May 1984. The Institute of Metals 38. S. Kamamoto et al., Analysis of Residual Stress and Distortion Resulting loom Quenching in Large Low-Alloy Steel Shafts, Mare,: Sci. TechnoL.Vol 1,Oct 1985, p 798-804 39. P. Jeanmart and J. Bouvaist, Finite Element Calculation and Measurement ofThermal Stresses in Quenched Plates of High-Strength 7075 Aluminum Alloy, Mater: Sri. Technol., Vol I, Ott 1985, p 765-769 40. A.J. Fletcher and A.B. Soomro, Effects of Transformation Temperature Range on Generation of Thermal Stress and Stress during Quenching, Mater: Sci. Technol., No. 2, July 1986, p 7 14-7 19 41. M. Gergely, S. Somogyi, and G. Buza, Calculation of Transformation Sequences in Quenched Steel Components to Help Predict lntemal Stress Distribution, Mates Sci. Tech&., Vol I, Ott 1985. p 893-898 42. B. Hildenwall and T. Ericsson, Prediction of Residual Stresses in CaseHardening Steels, in Hardenability Concepts with Applications to Steel, Symposium proceedings, 24-26 Ott 1977, D.V. Doane and J.S. Kirkaldy. ed, American Society for Metals, p 579-606 43. B. Hikienwall and T. Ericsson, How, why, and When Wii the Computed Quench Simulation be Useful for Steel Heat Treaters, in Compufers in Materials Technolog?: Proceedings of the Lntemational Conference, Linkiiping University, 4-S June 1980, T. Ericsson, ed.. Pergamon Press, p 45-53
Guidelines
for the Heat Treatment
of Steel
introduction Articles
in this chapter address the hands-on aspects of:
l
Normalizing
l
Annealing
l
Surface hardening
The Normalizing
l
l
Quenching/quenchants other processes) Tempering (including
(articles
on eight conventional
articles on martempering
processes and 17
and austempering)
Process
This process is often considered from both thermal and microstructural standpoints. In the thermal sense, normalizing is an austenitizing heating cycle, followed by cooling in still or agitated air. qpical normalizing temperatures for many standard steels are given in an accompanying Table. ln terms of microstructure, areas that contain about 0.8% C are pearlitic. Those low in carbon are ferritic.
Range of Applications AU standard, low-carbon, medium-carbon, and high-carbon wrought steels can be normalized, as well as many steel castings. Many weldments are normalized to refine the structure within the weld-affected zone, and maraging steels either can’t be normalized or are not usually normalized. Tool steels are generally annealed by the supplier. Reasons for normalizing are diverse: for example, to increase or decrease strength and hardness, depending on the thermal and mechanical history of the product.
Comparison of time-temperature cycles for normalizing and full annealing. The slower cooling of annealing results in higher temperature transformation to ferrite and pearlite and coarser microstructures than does normalizing. Source: Ref 1
In addition, normalizing functions may overlap with or be confused with annealing, hardening, and stress relieving. Normalizing is applied, for example, to improve the machinability of a pact. or to refine its grain structure, or to homogenize its grain structure or to reduce residual stresses. Tie-temperature cycles for normalizing and full annealing are compared in an adjoining Figure. Castings are homogenized by normalizing to break up or refine their dendritic structure and fo facilitate a more even response to subsequent hardening. Wrought products may be normalized, for example, to help reduce banded grain structure due fo hot rolling and small grain size due to forging. Details ofthree applications are given in an adjoining Table. including mechanical properties in the normalized and tempered condition. Normalizing and tempering can be substituted for conventional hardening when parts are complex in shape or have sharp changes in section. Otherwise. in conventional hardening such parts would be susceptible to cracking, distortion, or excessive dimensional changes in quenching. Rate of cooling in normalizing generally is not critical. However, when parts have great variations in section size. thermal stresses can cause distortion. Tie at temperature is critical only in that it must be sufficient to cause homogenization. Generally, a time that is sufticient to complete austenitization is all that is required. One hour at temperature, after a furnace has recovered, per inch of part thickness, is standard. Rate of cooling is significantly influenced by amount of pearlite. i& size, and spacing of pearlite IameUae. At higher cooling rates more pearlite forms and lamellae are finer and more closely spaced. Both the increase in pearlite and its greater fineness result in higher strength and hardness. Lower cooling rates mean softer parts. Cooling rates can be enhanced with fans to increase the strength and hardness of parts, or to reduce the time required, FoUowing the furnace operation, for sufficient cooling to allow workpieces to be handled. After parts cool uniformly through their cross section to black heat below Arl, they may be water or oil quenched to reduce total cooling time. Cooling center material in heavy sections to black heat can take considerable time.
Carbon
Steels
Steels containing 0.20% C or less usually are not treated beyond normalizing. By comparison, medium- and high-carbon steels are often tempered
28 / Heat Treater’s Typical
Normalizing
Guide Temperatures
Temperature(a) OF OC
Grade
Plain carbon steels 1015 915 1020 915 10’1 91s IO3 900 1030 900 IO35 88.5 lo40 860 104s 860 ioso 860 I060 830 IO80 830 1090 830 109s 8.45 III7 900 II37 885 II-II 860 II44 860 Standard alloy steels I330 900 1335 870 13-m 870 313s 870 31-m 870 3310 92s (a) Based on Production should be cooled in still
Typical
Grade
of Normalizing Steel
Cast50mm(?-in.)~akhcdy. 191025 mm C3/,to I in.) in section thickness
Ni-Cr-hlo
41.37 forging
Temperature(a) T OF
1IUl
and Tempering
Temperature(a) T OF
Grade
of Steel Components
Beat treatment Full annealed at 955 “C (I 750 “FI. notmtizedat 870°C (1600°F). tempered at 665 “C ( 1275 “F) Nomtized at 870 “C ( l6lXl ‘F). tempered at S70 “C ( 1060 “F) Normalized at 870 “C ( 1600 “Rand tempered
after normalizing, i.e., to get speciftc properties such as lower prior to straightening. cold working. or machining.
Alloy
Temperature(a) oc OF
Grade
I675 I675 1675 I650
Part
\‘d\r-honnet
Carbon and Alloy Steels
Standard alloy steels (continued) Standard alloy steels (continued) Standard alloy steels (continued) 4027 900 16.50 1700 8645 870 1600 1817 92s 4028 900 1650 1700 8650 870 1600 -1820 925 403’ 900 1650 870 1600 8655 870 1600 SO% 4037 870 1600 1700 8660 870 1600 5120 925 1650 4042 870 1600 5130 900 8720 92s 1700 1650 8740 92s 1700 I615 ‘m-17 870 1600 5132 900 870 1600 8742 870 1600 4063 870 1600 513s I575 4118 925 1700 870 1600 8822 925 1700 IS75 5140 870 I600 9255 900 16.50 IS75 4130 900 1650 51-E 413s 870 1600 870 1600 9260 900 1650 1525 5147 9262 900 1650 Jl37 870 1600 870 1600 IS?5 SISO 9310 925 1700 ‘II40 870 1600 870 1600 1515 5155 I.550 4142 870 1600 870 1600 9840 870 1600 5160 41-15 870 I600 1700 98SO 870 1600 6118 925 1650 41.47 870 I600 1700 SOB40 870 1600 I63 6120 9’5 1650 4150 870 1600 6150 900 SOB-M 870 1600 I575 4320 925 1700 1700 5OB-l.6 870 1600 157s 8617 925 4337 a70 1600 1700 508.50 870 1600 8620 91s 43-u) 870 I600 1700 60860 870 1600 8622 935 I650 4520 92s I700 1650 81835 870 1600 862.5 900 1600 86845 870 1600 4620 925 1700 1650 8627 900 I600 1650 4621 925 1700 8630 900 91BlS 925 1700 1600 870 1600 91Bl7 925 1700 4718 92s 1700 8637 I600 4720 925 1700 870 1600 91830 900 16.50 86-m 1700 4815 925 1700 870 1600 94B-U) 900 l6SO 8642 experience, normalizing trmpenture may \ary from as much a 28 “C (50 “F) helow. to as much as 55 “C (100 “FJ above. indicated temperature. The steel air from indicated tstitperature.
Applications
Forged flange
for Standard
hardness
Steels
Forgings, roUed products. and alloy steel castings are often normalized as a conditioning treatment before tinal heat treatment. Normalizing also reftnes grain structures in forgings. rolled products. and castings that have been cooled nonuniformly from high temperatures. Some alloys require more care in heating to prevent cracking from thermal shock. They also require long soaking times because of louer austenitizing and solution rates for c,arbon. Cooling rates in air to room temperature for many alloys must be carefully controlled. Some alloys are forced air cooled from the normalizing temperature to develop specific mechanical properties.
Forgings When forgings are normalized prior to carburizing or before hardening and tempering, the upper range of normalizing temperatures is used. But
Properties after treatment
Reason for
qormaRiing
To meet mechanical-property Tensile strength. 620 MPa (90 ksi); 0.X yield strength. -I IS hlPa (60 I&): requirements elongation in SOmm. or 1 in.. 20%; reduction in area. 40% To reline gmin size and obtain required Hardness. XXI to 23 HE hardness Hardness. 220 to 210 HB To obtain uniform structure, improved machinability, and required hardness
when normalizing is the tinal heat treatment, the lower temperature range is used. Small forgings are typicall> normalized as-received from the forge shop. Large. open die forgings are usually normalized in batch furnaces pyrometrically controlled to a narrow temperature range. Low-carbon steel forgings containing 0.2% C or less are seldom normalized. Multiple Treatments. Carbon and low alloy steel forgings with large dimensions are double normalized when forging temperatures are extremelj high (Ref 2) to obtain. for example, a uniform fine grain structure to pet specific properties such as impact strength to subzero temperatures.
Bar and Tubular
Products
Nomlalizing is not necessary and may be inadvisable when properties of these products obtained in the finishing stages of hot mill operation are close to those produced in normalizing. But reasons for normalizing bar and tube are generally the same as those that apply lo other steel products.
Guidelines
Castings In industrial practice, castings may be normalized in car bottom, box. pit, and continuous furnaces. Heal treatment principles are standard for all these furnaces. When higher alloy castings, such as C5, C I?, and WC9, are loaded, furnace temperatures should be controlled to avoid thermal shock that could cause metal failure. A safe loading temperature in this instance is in the range of 315 to 425 “C (600 to 795 “F). Lower alloy grades tolerate furnace temperatures as high as 650 “C (I200 “F). Carbon and low-alloy steel castings can be charged at normalizing temperatures. After charging, furnace temperatures are increased at a rate of approximately 225 “C (400 “F) per h, until the normalizing temperature is reached. Depending on steel composition and casting configuration, the heating rate
Annealing
Cycles
Cycles fall into three categories, cooling methods (see accompanying l
l
l
of Steel / 29
may be reduced to approximatelq 28 IO 55 “C (SO to 100 “F) per h, to avoid cracking. Extremely large castings may be heated more slowly to prevent the development of extreme temperature gradients. After normalizing temperature is reached. castings are soaked for a period that ensures complete austenitization and carbide solution. After soaking, parts are unloaded and allowed to cool in still air. Use of fans, air blasts. or other means of speeding up the cooling process should be avoided.
References I. G. Ksauss, Sleels: Heor Treurrnerrr cm1 Processing Principles, International. Metals Park, OH, 1990 2. A.K. Sinha. Ferrars Pi~~sical Memll~r~~, Butterworths, 1989
ASM
of Steel
Ln this process, steels are heated to a specific temperature, held at Ihat temperature for a specific time, then cooled at a specific rate. Generally, in treating plain carbon steels, a ferrite-pearlite microstructure is produced (see adjoining Figure). Softening is the primreason for annealing. Other important applications are to facilitate cold work or machining, IO improve mechanical or electrical properties, or LO promote dimensional stability.
Annealing
for the Heat Treatment
based on heating table):
temperatures
and
Subcritical annealing-the maximum temperature may be below the lower critical temperature, A 1 Inlercritical annealing--the maximum temperature is above Al, but below the upper critical temperature, A3, for hypoeutectic steels. or AC,,, for hypereutectic steels Full annealing-the maximum temperature is above A3
Austenite is present at temperatures above Al, so cooling practice (see Table) through transformation is a critical factor in getting the desired microstructure and properties. Steels heated above A 1 are subjected LO slow, continuous cooling, or to isothermal treatment at a temperature below
A fully annealed 1040 steel showing a ferrite-pearlite structure. Etched in 4% picral plus 2% nital. 500x
micro-
Al, at which transformation to the microstructure wanted can occur in a reasonable time. In some applications, two or more annealing cycles are combined or used in succession to get a specilied result.
Subcritical
Annealing
Austenite is not formed in this type of treatment. The prior condition of a steel is modified by such processes as recovery, recrystallization, grain growth. and agglomeration of carbides. The prior history of a steel is important in subcritical annealing. In treating as-rolled or forged hypoeutectoid steels containing ferrite and pearlite, the hardnesses of both constituents can be adjusted. But if substantial softening is the objective, times at temperature can be excessively long. Subcritical annealing is most effective on hardened or cold worked steels, which recrystallize readily LOform new ferrite grains. The rate of softening increases rapidlq as the temperature approaches Al. A more detailed discussion of subcritical annealing is found in Ref I.
Intercritical
Annealing
Austenite begins to form when the temperature of the steel exceeds Al. Carbon solubility rises abruptly (nearly 1%) near the Al temperature. In hypocutectoid steels. the equilibrium structure in the intercritical range between Al and A3 consists of ferrite and auslenite, and above Aj. the smcture becomes totally austenitic. But the equilibrium mixture of ferrite and austenite is not obtained immediately. For example. Ihe rate of solution for a typical eutectoid steel is shown in an accompanying Figure. In hypereutectoid steels. carbide and austenite coexist in the intercritical range betn een A I and A,-,,,. The most homogeneous structure developed at h&her austenitizing temperatures tends to promote lamellar carbide struclures on cooling. while lower austenitizing temperatures result in less homopenous nustenite. which promotes the formation of spheroidal carbides. Temperature-time plots shoiving the progress of austenite formation under isothermal (IT) or continuous transformation (CT) conditions for many steels have been published (Ref 2,3). Cooling After Full Transformation. After complere transformation to austenite. little else of metallurgical consequence can occur during cooling to room temperature. Extremely slow cooling can cause some agglomeration of carbides, and, consequently. some slight additional softening of the steel: but in this case. such slow cooling is less effective than high-temperature transformation. This means there is no reason for slow cooling after transformation is completed and cooling from the uansformation temperature may be as rapid as is feasible to minimize the time needed for the operation.
30 / Heat Treater’s
Approximate
Steel 1010 I020 1030 IO40 1050 loa 1070 1080 1340 3140 4027 4042 4130 4140 4150 4340 4615 5046
5120 51-U) 5160 52100 6150 8115 8620 8640 9260
Austenitizing
Guide
Critical
Temperatures
Critical temperaACI T OF 725 725 725 725 725 725 725 730 715 735 725 725 760 730 745 725 725 715 765 740 710 725 750 720 730 730 745
1335 I335 1340 I340 1340 1340 1340 1345 1320 1355 1340 1340 I395 1350 1370 1335 1340 I320 1410 1360 1310 1340 1380 1300 1350 I350 1370
for Selected
Carbon and Low-alloy
on heating at 28 “C/h (SOOF/h) AC, T OF 875 845 815 795 770 745 730 735 775 765 805 795 810 805 765 775 810 770 840 790 765 770 790 840 830 780 815
1610 1555 I495 1460 1415 I375 I350 I355 1430 I-110 1485 1460 1490 I480 I410 1325 1490 I-120 I540 I450 1410 I415 l-150 I540 I525 1135 1500
Steels Critical temperatures on cooling at 28 “c/b (50 OF/h) An An OF T T OF 850 815 790 755 740 725 710 700 720 720 760 730 755 745 730 710 760 730 800 725 715 715 745 790 770 725 750
1560 1500 I450 I395 I365 1340 1310 1290 1330 1330 1100 I350 I390 1370 1335 1310 I400 1350 1470 1340 I320 I320 I370 1450 141.5 1340 1380
680 680 675 670 680 685 690 695 620 660 670 655 695 680 670 655 650 680 700 695 675 690 695 670 660 665 715
1260 I250 I240 1260 1265 I275 1280 II50 1220 I240 1210 1280 1255 I240 1210 1260 1290 1280 1250 1270 1280 1240 I220 1230 1315
rate-temperature curves for comnmercial plain carbon eutectoid steel. Prior treatment was normalizing from 675 “C (1605 OF); initial structure, fine peariite. First curve at left shows beginning of disappearance of pearlite; second curve, final disappearance of pearlite; third curve, final disappearance of carbide; fourth curve, final disappearance of carbon concentration gradients.
Guidelines
for the Heat Treatment
of Steel / 31
The iron-carbon binary phase diagram showing region of temperatures for full annealing (Ref 4)
Recommended
Temperatures
and Cooling
Cycles for Full Annealing
Data are for forgin s up to 75 mm (3 in. in section thickness. Time at temperature thick; l/2 h is adde 8 for each additional 3 5 mm (1 in.) of thickness.
of Small Carbon Steel Forgings usually is a minimum of 1 h for sections up to 25 mm (1 in.)
Cooling cycle(a) Annealing
temperahwe
T
OF
Steel
T
OF
From
To
From
1018 IO.20
85WOO
lo22
85WOO 855~900
1575-1650 1575-1650 lS75-1650 1575-1650 ISSO-1625 ISSO-162s 1350-I600 IJSO-1600 IdSO-1600 1450-1550 1450-1550 1150-1550 1450-1525 1450-1525
855 855 855 855 8-U 845 790 790 790 790 790 790 790 790
705 700 700 700 650 650 650 650 650 650 6.50 650 650 655
1575 1575 1575 1575 1550 1550 1150 I-150 1150 1150 1450 l-150 l-i50 I-WI
1025 1030
1035 1040 1045 IO50 1060 1070 1080 1090 IO95 (a)
ass-900 845-885 845-885 790-870 790-870 790.870 790-845 790-845 79o-a-is 790-830 790-830
Furnacecooling at 28 “C/h (SO”F/h)
To
Eardness range, FIB Ill-149 Ill-149 Ill-14cf Ill-187 126-197 137-207 137-207 156-217 156-217 156-217 167-229 167-229 167-229 167-229
32 / Heat Treater’s Guide Recommended Annealing Temperatures for Alloy Steels (Furnace Cooling) AISI/SAE Steel 1330 1339 13-m I345 31-m 4037 -Ku2 40.47 4063 1130 -II35 4137 -1140 314S 1147 1150 1161 3337 -t34O SOB40
SOB-U SO46 SOB-t.6 SOB60 5130 Sl32 513s 51-m 5145 Sl47 5150 515s 5160 SIB60 so100 51100 VI00 6150 81815 8627 X630 8637 8640 8643 86-E 86B4S x61650 86SS 8660 8740 874' 9360 94B30 94B10 9840
Supercritical
Annealing temperature T OF &Is-900 849-900 84S-900 81.5-900 815.870 8 I S-855 815.8SS 790.845 790-815 790-815 790-849 790-815 790-a-15 790-845 790-845 790-845 79c-8-n 790.845 790-845 815-870 815-870 8 I S-870 8 I S-870 815-870 8 I S-870 790-815 790-845 815-870 815-870 8 I S-870 815-870 X15-870 815-870 8 I S-870 81%870 730-790 730-790 730-790 845900 845-900 815-870 790-845 8 I S-870 8 I S-870 8 I S-870 815-870 815-870 815870 815-870 815870 t-415-870 8 I S-870 815.870 790-x15 790-84.5 790-845
ISSO- I650 ISSO-1650 ISSO-I650 ISSO-I650 I SOO- I600 1500-1575 1500-157.5 I -Iso- I 550 I GO- I sso I4SO- ISSO 1450-1550 I -so- I SSO l-150- ISSO 1450-1550 14.50-1550 l-150. ISSO l1SO- ISSO l-150- ISSO I-m- I SSO 1500-1600 1500-1600 1500-1600 1500-1600 ISOO-I600 ISO@ I-ISO- ISSO 1450-1550 ISOO-I600 ISO@ ISO@ 1500-1600 1500-1600 1500-1600 1500-1600 1500-1600 I3SO- I450 I3SO- I -is0 1350. IJSO 1550-1650 I SSO- I650 1500-1600 l1SO- I sso 1500-1600 1500-1600 1500-1600 1500-1600 ISOO-I600 ISCO-1600 1.500.1600 1500-1600 1500-1600 1500-1600 lSOWl600 11.50-1550 I-150- IS50 I -Iso- I sso
Spheroidized microstructure of 1040 steel after 21 h at 700°C (1290 oF). 4% picral etch. 1000x
HWdlll?SS
@au), RB 179 I87 I92 I87 I83 I92 201 233 I74 192 197 '07 212
223 I87 197 I92 I92 201 217 I70 170 17-I I87 I97 197 201 717 2'3 223 I97 197 207 201 I92 I74 179 I92 197 201 207 207 212 "3 --. '29 203 229 I74 192 207
or Full Annealing
Full annealing, a common practice, is obtained by heating hypoeutectoid steels above the uppercritical temperacure, Aj. Ln treating these steels (they are less than 0.77% in carbon content). full annealing takes place in the austenite region at the annealing temperature. However. in hypereutectoid steels (they are above 0.77%, in carbon content), annealing takes place above the At temperacure. which is the dual phase austenite region. In an
adjoining Figure. the annealing superimposed on an iron-carbon,
temperature range for full annealing is binary phase diagram. Austenitizing Time and Dead Soft Steel. Hypereutectoid steels can be made extremely soft by holding for long periods at austenitizing temperatures: there is little effect on hardness, i.e., at a change from 241 to X9 HB, the effect on machining or cold forming properties may be substantial.
Annealing
Temperatures
In specifying many annealing operations, it isn’t necessary to go beyond stating that the steel should be cooled in the furnace from a designated austenitizing temperature. Temperatures and associated hardnesses for simple annealing of carbon steels are given in an adjoining Table: requirements for alloy steels are in another Table. Heating cycles in the upper austenitizing temperature ranges shown in the Table for alloy steels should result in pearlitic structures. At lower temperarures. structllres should be predominately spheroidized. Most steels can be annealed by heating to the austenitizing temperature then cooling in the furnace at a controlled rate, or cooling rapidly to, and holding at, a lower temperature for isothemutl transformation. With either procedure, hardnesses are vir~ally the same. However, isothermal transformation takes considerably less time.
Spheroidizing This treatment is usually chosen to improve cold formability. Other applications include improving the machinability of hypereutectoid steels and tool steels. This miCroStruCture is used in cold forming because it lowers the flow stress of the materials. Flow stress is determined by the proportion and distribution of ferrite and carbides. Ferrite strength depends on its grain size and rate of cooling. The formability of steel is signiticantly affected by whether carbides are in the lamellae or spheroid condition. Steels may be heated and cooled to produce globular carbides in a ferritic matrix. An adjoining Figure shows IO-IO steel in the fully spheroidized condition. Spheroidization can take place by using the FoUowing methods: l Prolonged holding at a temperature just belo- the Act l Heating and cooling alternately between temperatures that are just above Act and just below Art l Heating to a temperature just above Act, and then either cooling very slowly in the furnace. or holding at a temperature just above Art l Cooling at a suitable rate from the minimum temperature at which all carbide is dissolved to prevent the reformation of carbide networks, then reheating in accordance with the fist or second methods described
Guidelines for the Heat Treatment of Steel / 33
The iron-carbon binary phase diagram showing region of temperatures for spheroidizing
Effect of prior microstructure [as-quenched).
on spheroidizing
(b) Starting from a ferrite-pearlite
(Fief 4)
a 1040 steel at 700 “C (1290 OF) for 21 h. (a) Starting from a martensitic microstructure microstructure
(fully annealed).
Etched in 4% picral plus 2% nital. 1000x
34 / Heat Treater’s Guide previously work)
The extent of spheroidization at 700 “C (1290 OF)for 200 h for the 1040 steel starting from a ferrite-pearlite microstructure etched in 4% picral. 1000x
(applicable
to hypereutectoid
steel containing
a carbide net-
The range of temperatures for spheroidizing hypoeutectoid and hypereutectoid steels is shown in an adjoining Figure. Rates of spheroidizing depend somewhat on prior microstructures, and are the greatest for quenched structures in which the carbide phase is fine and dispersed (see Figures). Prior cold work also increases the rate of the spheroidizing reaction in a subcritical spheroidizing treatment. For full spheroidization, temperatures either slightly above Act or about midway between Act and ACJ are used. Low-carbon steels are seldom spheroidized for machining because in this condition they are excessively soft and gummy, and produce long, tough chips in cutting. Generally, spheroidized low-carbon steel can be severely deformed. Hardness after spheroidization depends on carbon and alloy content. Increasing carbon or alloy content, or both, results in an increase in as-spheroidized hardness, which generally ranges from I63 to 212 HB (see adjoining Table).
Process
Annealing
As a steel’s hardness goes up during cold working, ductility drops and further cold reduction becomes so difficult that the material must be annealed to restore its ductility. The practice is referred to as in-process
Recommended Temperatures and Time Cycles for Annealing of Alloy Steels Conventional
Steel
temperature OF T
To obtain a predominantly I340 a30 2340 800 2345 800 312qd) 88s 31-m a30 3150 a30 33low a70 4042 a30 w7 a30 4062 a30 4130 ass 4l4O 83s 41.50 a30 432qd) a85 a30 4340 4620(d) 885 4640 a30 3820(d) 5045 a30 Sl2qd) 88s 5132 a45 SIUI a30 5150 a3o S2loom 6150 a30 a62qd) 88s a630 a45 a640 a30 8650 a30 a660 a30 8720(d) a85 8710 a30 8750 a30 9260 860 93 IO(e) a70 98-m a30 9aso a30
cooliog(a)
Ikmperahu-e
Austenitixhg
T From
pearlitic structure(c) IS25 735 1475 655 1475 655 1625 1525 735 IS25 705 I600 74s 1515 I525 735 IS25 695 I575 765 I550 755 IS25 745 1625 1525 705 1625 1525 715
OF
Cooling rate OClh OFlh
Tie, h
To
From
To
610 555 550
I350 1210 I210
II30 1030 1020
IO as as
20 I5 IS
II I2 12.7
650 64s
1350 I300
I200 ll9o
IO IO
20 20
7.5 5.5
640 630 630 665 665 670
1370 I350 1280 1310 I390 1370
ii80 II70 1170 1230 1230 I240
IO IO a.5 20 I5 a.5
20 20 I5 3s 25 IS
9.5 9 7.3 5 6.4 8.6
565
13cil
1050
a.5
IS
16.5
600
I320
Ill0
7.6
1-I
IS
IS25 I635 I550 IS25 152s
755
66s
I390
I230
IO
20
a
755 7-m 705
670 670 650
I390 I360 I300
l2Ul 1240 I200
IO IO IO
20 10 20
7.5 6 5
I525 16’5 I550 IS’5 IS25 1525 I625 I525 1525 IS75 16cQ IS25 I525
760
675
I-NO
I250
as
I5
735 725 710 700
6-m 640 650 655
I350 l34o 1310 I290
ii80 ii80 1200 I210
IO IO a.5 a.5
20 20 IS IS
as a 7.2 a
725 720 760
645 630 705
13-w 1330 I-too
II9o II70 I300
IO a.5 a.5
20 I5 IS
7.5 10.7 6.7
695 700
640 645
I 280 1290
ilao II9O
a.5 a.5
IS I5
6.6 6.7
IO
Isothermal method(b) Cool to OF Eold,h T
Elardness (PpProX), EJ3
620 595 595 650 660 660 595 660 660 660 675 675 675 660 650 650 620 605 660 690 675 675 675
II50 Iloo Iloo 1200 I225 I225 Iloo I225 1225 I225 1250 I250 1250 1225 IXO 1200 II50 II25 I225 I275 I250 1250 I250
4.5 6 6 4 6 6 I4 4.5 5 6 4 5 6 6 a 6 a 4 4.5 4 6 6 6
la3 201 201 179 la7 201 la7 197 207 223 174 197 212 197 223 la7 197 I92 I92 179 la3 la7 201
675 660 660 660 650 650 660 660 660 660 595 650 650
1250 1225 1225 I225 I200 1200 1225 I225 I235 1225 llccl IZOO I200
6 4 6 6 a a 4 7 7 6 I4 6 a
201 la7 I92 197 212 229 la7 201 217 229 ia7 207 223
Guidelines for the Heat Treatment of Steel / 35 Recommended Temperatures and Time Cycles for Annealing of Alloy Steels (continued) Attstenitizii
Steel
temperature T OF
T From
Conventional cooling(a) Temperature OF Cooling rate To To From “CP Wl
Tie, h
Isothermal method(b) Cool to T OF Hold, h
Eardness (apF)v
To obtaio a predominantly ferritic and spheroidized carbide structure 1320(d) 1340 23-U) 2345 3 120(d) 3140 3150 9840 9850
805 750 715 71s 790 745 750 745 745
1180 1380 I320 1320 1450 1370 1380 1370 I370
.. 735 655 655
.‘. 610 555 550
... 1350 1’10 I210
1130 “’ 1030 IO20
5 5 5
IO IO IO
22“’ 18 I9
735 705 695 700
650 64s 640 64s
1350 1300 I280 I290
I200 ... I190 I I80 II90
5 5 5 5
IO IO IO IO
ii II II II
650 640 605 605 650 660 660 6SO 650
I200 II80 II25 II25 1200 1225 1225 I200 I200
8 8 IO IO 8 IO IO IO I2
170 174 I92 I92 163 I74 I87 I92 207
(a) The steel is cooled in the furnace at the indicated rate through the temperature range shown. (b) The steel is cooled rapidly to the temperature indicated and is held at that temperature for the time specified. (c) ln isothermal annealing to obtain pearlitic StrucNre. steels may be austenitized at temperaNreS up to 70 “C ( I25 “F) higher than temperatures listed. (d) Seldom annealed. !hIKNreS of better machinability are developed by normalizing or by transforming isothermally after rolling or forging. (e) Annealing is imptactical by the conventional process of continuous slo\c cooling. The louer transformation temperature IS markedly depressed, and excessively long cooling cycles ate required to obtain are seldom desired in this steel. transformation to pearlite. (I) Predominantly pearlitic struc~res
The iron-carbon binary phase diagram showing region of temperature for process annealing (Ref 4)
36 / Heat Treater’s Guide annealing or simply process annealing. ln most cases, a SubcriIical treatment is adequate and the least costly procedure. The term process annealing, without further qualification. refers to the subcritical treatment. The range of temperatures normally used are shown in an adjoining Figure. It is often necessary to call for process annealing when parts are cold formed by stamping, heading, or extrusion. Hot worked, high-carbon and alloy steels are also process annealed to prevent them from cracking and to soften them for shearing, turning. and straightening. The process usualI> consists of heating to a temperature below AC,. soaking for an appropriate time. then cooling-usually in air. Generally, heating to a temperature between IO and 22 “C (20 and 10 “F) below AC] produces the best combination of microstructure, hardness, and mechanical properties. Temperature controls are necessary only to prevent heating above Act. which would defeat the purpose of annealing. When Ihe sole purpose is to soften for such operations as cold sawing and cold shearing, temperatures are usually well below Act. and close control isn’t necessary.
Annealed
Structures
for Machining
Different combinations of microstructure and hardness are important for machining. Optimum microstructures for machining steels with different carbon contents are usually as follows: Carbon, W 0.c60.20 0.20-0.30
0.30-0.40 0.00-0.60
[email protected]
Optimum microslructure As-rolled (,mosteconomical) Under75 mm (3 in.)diameter,normaliz.ed: 75 mm diameterando\er. as-rolled Annealed to produce coarse pearlite. minimum ferrite Coarse Iamellar pearlite to coarse spheroidized carbides 100%.spheroidizrd carbides. coarse to fine
qpe of machining operation must also be taken into consideration, i.e., in machining 5160 steel tubing in a dual operation (automatic screw machines. plus broaching of cross slots), screw machine operations were the easiest with thoroughly spheroidized material. H hilt a pearlite smcture was more suitable for broaching. A senispheroidized structure proved to be a satisfactory compromise-a structure that can be obtained by austenitizing at lower temperatures, and sometimes at higher cooling rates, than those used to get pearlitic structures. In the last example, the 5 160 tubing was heated to 790 “C ( I455 “F) and cooled to 650 “C ( I200 “F), at 28 “C (50 “F) per h. When this grade of steel is austenitized at about 775 “C (I125 “F), results are more spheroidization and less pearlite. Medium-carbon steels are harder to carburize than high-carbon steels, such as IO95 and 52 100. In the absence of excess carbides to nucleate and
Surface
Hardening
promote the spheroidization reaction, it is more difficult to get complete freedom from pearlite in practical heat-treating operations. At lower carbon levels, structures consisting of coarse pearlite in a ferrite matrix are the most machinable. With some alloy steels, the best way of getting this type of structure is to heat well above Ac3 to establish coarse austenite gram size, then holding below Art to allow coarse, lamellar pearlite to form. The process is sometimes referred to as cycle annealing or lamellar annealing.
Annealing
Annealing
Significant tonnages of these products are subjected to treatments that lower hardness and prepare the steels for subsequent cold working and/or machining. Short time, subcritical annealing is often enough to prepare low-carbon steels (up to 0.204; C) for cold working. Steels higher in carbon and alloy content require spheroidization to get maximum ductility.
Annealing
of Plate
These products are occasionally annealed to facilitate forming or machining operations. Plate is usually annealed at subcritical temperatures, and long annealing times are generally avoided. Maintaining flatness of large plate can be a significant problem.
Annealing
of Tubular
Products
Mechanical tubing is frequently machined or formed. Annealing is a common treatment. In most instances, subcritical temperatures and short annealing times are used to lower hardness. High-carbon grades such as 52100 generally are spheroidized prior to machining. Tubular products made in pipe mills rarely are annealed. and are used in the as-rolled, the normalized, or quenched and tempered conditions.
References B.R. Banerjee, Annealing
Heat Treatments,
Met. frog..
Nov 1980, p 59
Atlas of Isorhent~al Transfomtariot~ and Cooling Transformation Diagratns. American Society for Metals, 1977 hl. Atkins, Ailas for Cotlriturous Cooling Transfomtarion Diagramsfor Engineering Steels, American Society for Metals, in cooperation with British Steel Corporation.
G. Krauss, Sleek: International.
processes
l l l
Induction hardening l Flame hardening l Gas carbutizing l Pack carbutizing l Liquid carburizing and cyaniding l Vacuum carburizing l Plasma (ion) carburizing . Carbonitriding
Bar, Rod, Wire
1980
Hear Treammenr and Processing Principles, ASM
1989
Treatments
In the articles that follow, overvie\% s of I6 surface hardening are presented. They include. in the order that follows: l
of Forgings
Forgings are most often annealed to facilitate subsequent operationsusually machining or cold forming. The method of annealing is determined by the kind and amount of machining or cold fomting to be done, as well as type of material being processed.
l l l l l
Gas nitriding Liquid nitriding Plasma (ion) nitriding Gaseous and plasma nitrocarburizinp Fluidized bed hardening Boriding Laser surface hardening Electron beam surface hardening For more detailed
information
and hundreds of references, see the ASM IO ed., ASM International, 1991.
Metals Handbook. Hear Treating. Vol1.
Guidelines
Induction
h4any problems associated with furnace processes are avoided. Rate of heating is limited only by the power rating of the alternating current supply. Surface problems such as scaling and decarburization and the need for protective atmospheres often can be bypassed because heating is so fast. Heating is also energy efficient-as high as 80 percent. In gas fued furnaces. by comparison, a fairly substantial amount of consumed energy in hot gases is lost as they exit the furnace. HoNever, the process seldom competes with gas or oil-based processes in terms of energy costs alone. SaGngs emanate from other sources:
Characteristics In designing treabnents, consideration must be given to the workpiece materials, their starting condition, the effect of rapid heating on the ACT or Accm temperatures, property requirements, and equipment used.
and Production
Material
Rounds 13 19 ‘5 29 49
4130 IO35 mod IMI 1041 13B3SH
‘/z
Flats 16 I9 22 25 29
5/g 34 ‘4% I I ‘/8
lrregularshapes 17.5-33 “/16-15/lb 17.529 ‘Vlh-lt/~
Data for Progressive FIX?quencyb), Ez
Section size mm in.
% I I ‘/8 I ‘V,6
of Steel / 37
Hardening
Steels are surface hardened and through-hardened, tempered, and stress relieved by using electromagnetic induction as a source of heat. Heating times are unusually rapid-typically a matter of seconds, Ref I.
Operating
for the Heat Treatment
1038 1038 1043 1043 lo-13 t037mod t037mod
9600 9600 9600 180
Induction
Tempering
Power(a), kW
Total heating time,s
II 12.7 18.7 20.6 23
17 30.6 d-I.2 51 196
0.39 0.71 I .01 1.18 2.76
I 1.8 2.6 3.0 7.0
SO SO so SO 50
120 I20 I20 I20 I20
56s 510 565 565 56.5
1050 9.50 IOSO 1050 IOSO
I23 I64 312 25-l 328
0.59 0.79 I so 1.22 I .57
I.5 2.0 3.8 3I 1.0
40 40 -lo 10 40
loo 100 100 loo loo
‘90 31s 290 290 290
550 600 950 550 550
0.9-l 0.67
2.1 I.7
65 65
IS0 IS0
550 125
IO70 800
60 60 60 60 60
88 too 98 85 90
9600 9600
I92 IS-I
64.8 46
Sean time s/cm sjm.
Work temperature Leabing coil Entering coil OF T T OF
Production rate ki# lblb
Inductor illput kW/cmz kWlm.2
0.064 0.050
92 II3 I11 IS3 I95
202 ‘SO 311 338 429
0.054 0.053 0.031
0.4 I 0.32 0.35 0.34 0.20
I449 1576 1609 1365 1483
319-t 3171 3548 3009 3269
0.01-l 0.013 0.008 0.01 I 0.009
0.089 0.08 I 0.0.50 0.068 0.060
2211 3875 2276 5019
0.043 0.040
0.28 0.26
(a) Power tmnsmitted by the inductor at the operating frequency indicated. For con! erted frequencies. this po\\er is approximately ?S@kless than the power input to the machine, because of losses within the machine. (b) At the operating frequency of the inductor
Examples
of quench
rings for continuous
hardening
and quenching
of tubular
members.
Courtesy
of Ajax Magnethermic
Corp.
38 / Heat Treater’s
Guide
Power Densities
Required
Frequency, KEZ
Depth of hardening(a) in. mm
500
for Surface
0.381-1.143 1.143-2.286 1.524-2.286 2.286-3.048 3.0483.064 2.286-3.048 3.048-4.064 4.064-5.080 5.080-7. I I2 7.112-8.890
IO
3
I
Hardening
Of Steel ~PMJ)W Optimum(e) kW/cmz kWrm.2
Low(d) kW/cmz
kW[m.’
I .08 0.46 I .24 0.78 0.78 I s5 0.78 0.78 0.78 0.78
7 3 8 5 5 IO 5 5 5 5
0.015-0.045 0.045-0.090 0.060-0.090 0.090-0. I20 O.I20-0.160 0.090-0. I20 0.120-O. I60 0.160-0.200 0.200-0.280 0.280-0.350
I.55 0.78 I .ss I ss I .55 2.33 2.17 I .55 I .55 I.55
em kW/cm
10 5 IO IO IO I5 I4 10 IO IO
kWtin.2 I2 8 I6 I5 I4 I7 I6 I4 I2 I2
I.86 I .24 2.48 2.33 2.17 2.64 2.48 2.17 1.86 I.86
(a) For greater depths of hardening, lower kilowatt inputs are used. (b) These values are based on use of proper frequency and normal overall operating efficiency of equipment. These values may be used for both static and progressive methods of heating; however, for some apptications. higher inputs can be used for progressive hardening. (c) Kilowattage is read as maximum during heat cycle. (d) Low kilowatt input may be used when generator capacity is limited. These kilowatt values may be used to catculate largest part hardened (single-shot method) with a given generator. (e) For best metatturgical results. (f) For higher production when generator capacity is available
Approximate Operations
Power Densities
Required
for Through-Heating
of Steel for Hardening,
Tempering,
or Forming
Input(b) 150-425T (30Mtoo°F) kW/cm’ kWrm.2
~uency(a), 62 60 I80 1009 3000 10000
0.009 0.008 0.006 0.00s 0.003
421760 T (soo-1400°F) kW/cmz kWlin.2
0.06 0.05 0.04 0.03 0.02
0.023 0.022 0.019 0.016 0.012
76M80 T (1400-BOOoF) kW/cmz kwp.*
0.15 0.14 0.12 0.10 0.08
(c) w 0.08 0.06 0.05
980-lo!zOc (1&300-2ooooF) k W/cm2 kW/in.” Cc) (c) 0.155 0.085 0.070
0.5 0.4 0.3
1095-l205oc (2tmo-2200 OF) kW/ii2 kW/cml w w 0.22 0.11 0.085
I .o 0.55 OX?
(c) w 1.4 0.7 0.55
(a) The values in this table are based on use of proper frequency and normal overall operating efficiency ofequipment. (b) In general, these power densities are for section sizes of I3 to SOmm ( ‘/? to 2 in.). Higher inputs can be used for smaller section sizes, and lower inputs may be required for larger section sizes. (c) Not recommended for these temperatures
Typical
Operating
section size mm in. Rounds I3
‘/z
Conditions
for Progressive
Through-Hardening
of Steel Parts by Induction
Material
Frequency(a), El2
Power(b), kW
Total beating time,s
4130
I80
20 21 28.5 20.6 33 19.5 36 19.1 35 32
38 I7 68.4 28.8 98.8 44.2 II4 fit 260 II9
0.39 0.39 0.7 I 0.71 I .02 1.02 I.18 I.18 2.76 2.76
I I8 I.8 2.6 2.6 3.0 3.0 7.0 7.0
75 sto 75 620 70 620 75 620 75 635
I65 950 I65 II50 I60 II50 I65 II50 I65 II75
510 925 620 955 6’0 955 630 95s 635 95.5
950 1700 IISO I750 II50 1750 IISO I750 II75 1750
92 92 II3 II3 I41 I31 IS3 I53 19.5 I95
202 202 250 250 311 311 338 338 429 429
0.067 0.122 0.062 0.085 0.054 0.057 0.053 0.050 0.029 0.048
0.43 0.79 0.40 0.55 0.35 0.37 0.34 0.32 0.19 0.31
I80 9600 I80 9600 I80 9600 I80 9600
scao time s/cm Sri.
I
Work temperature Entering coil Leaving coil ‘=C OF T “F
Production rate lblh k%h
Inductor input(c) kW/cml kW/in.l
I9
34
1035 mod
25
I
1041
29
I ‘/*
IO41
19
I ‘V, 6
I4B3SH
% 3/a ‘4 I I ‘/8
1038 1038 1043 IO36 1036
3000 3000 3000 3000 3000
300 332 336 30-I 34-l
II.3 I5 38.5 26.3 36.0
0.59 0.79 I so I .38 I.89
I.5 2.0 3.8 3.5 4.8
20 ‘0 20 20 ‘0
70 70 70 70 70
870 870 870 870 870
1600 1600 1600 1600 1600
1449 1576 1609 IS95 I678
3193 347-l 3548 3517 3701
0.361 0.319 0.206 0.225 0.208
2.33 2.06 I .33 I .45 I.34
t037mod
3ooo
580
25-t
0.94
2.4
20
70
885
1625
2211
4875
0.040
0.26
Flats I6 I9 22 25 ‘9
Irregular shapes 17.5-33 t’/te-15/ts
(a) Note use of dual frequencies for round sections. (b) Power transmitted by the inductor at the operating frequency indicated. This poaer is approximately 25% less than the power input to the machine, because of losses within the machine. (c) At the operating frequency of the inductor
Guidelines
Eleven basic arrangements for quenching induction-hardened
shortened processing times, reduced labor, and the ability to heat treat in a production line or in automated systems, for example. Surface hardening and selective hardening can be energy competitive because only a small part of the metal is heated. [n addition, with induction heating it often is possible to substitute a plain carbon steel for a more expensive alloy steel. Short heating times make it possible to use higher austenitizing temperatures than those in conventional heat-treating practice. Less distortion is another consideration. This advantage is due to the support given by the rigid, unheated core metal and uniform, individual handling during heating and quenching cycles.
Operating
Information
Power densities for surface hardening are given in an adjoining Table. Approximate power densities needed for through-heating of steel for hardening and tempering are given in an adjoining Table. Typical operating conditions for progressive through-hardening are given in an adjoining Table.
for the Heat Treatment
of Steel / 39
parts. See text for details.
Operating and production data for progressike induction tempering are given in an adjoining Table. Frequency and power selection influence case depth. A shallow, fully hardened case ranging in depth from 0.25 mm to I .5 mm (0.010 to 0.060 in.) provides good resistance to wear for light to moderately loaded parts. At this level, depth of austenitizing can be controlled by using frequencies on theprder of IO KHz,to 2 MHz, power densities to the coil of 800 to 8000 W/cm’ (5 to 50 kW/i.-) and heating times of not more than a few seconds.
For parts subjected to heavy loads, especially cyclic bending, torsion, or brinneling. case depths must be thicker. i.e.. 1.5 IO 6.4 mm (0.060 to 0.250 in.j. To get this result. frequencies range from 10 KHz down to I KHz; power densities are on the order of 80 to 1550 W/cm2 (l/2 to IO kW/in.2). and heating times are several seconds. Selective hardening is possible, as is in volume surfacing hardening, in which parts are austenitized and quenched to greater than usual depths. Depth of hardness up to 25 mm (I in.) measuring over 600 HB has been obtained with a I percent carbon. I .3 to I .6 percent chromium steel that has been water quenched. Frequencies range from 60 Hz to 1 KHz. Power
40 / Heat Treater’s
Guide
Power Input for Static Hardening. Slope of graph indicates that 35 to 40 kW-seciin.’ (5 to 6 kW-secicm’) is correct power input for static hardening most steels. Source: Park-Ohio Industries
Straight-line Relationships Between Depth of Hardnessand Rate of Travelfor Surface Hardening by Induction of long Bars Progressively. Source: Park-Oh10 lndustrles
Effect of Varying Power Density on Progressive Hardening. Power density at 10 000 cycles. Case, 0.100 in. (2.54 mm) deep. Park-Ohio Industries
Source:
Guidelines
for the Heat Treatment
of Steel / 41
Minimum Power Density VersusStock Diameter for Static Hardening and VersusRate of Travel for Progressive Hardening. Source: Park-Oh10 Industries
Influence of Prior Structure on Power Requirements for Surface Hardening. Prior structure consists of fine microconstituents.
Source: Park-Ohio Industries
42 / Heat Treater’s
Guide
Effect of Varying Power Density on Progressive Hardening. Power density at 500 000 cycles. Case, 0.050 In. (1.27 mm) deep. Source: Park-Ohio Industries
densities are expressed in a fraction of kW/in.‘. Heating times run from about 20 to 140 s. Through-hardening is obtained in the medium frequencies (180 Hz to IO KHz). In some instances, two hequencies may be used, a lower one to preheat the steel to a subcritical temperature, followed by a higher ti-equency to obtain the full austenitizing temperature. Tempering with induction heating is highly efficient. The two most common types of quenching systems are spray quench rings (see Figure) and immersion techniques. Eleven other systems are shown in an adjoining Figure. Water and oil are the most frequently used quenching media. Oil typically is used for high hardenability parts or for those subject to distortion and cracking. Polyvinyl alcohol solutions and compressed air also are commonly used, i.e., the former where parts have borderline hardenability. where oil does not cool fast enough, and where water causes distortion or cracking. Compressed air quenching is used for high hardenability, surface hardened steels from which little heat needs to be removed.
Flame
Applications The process is applied mostly to hardenable grades of steel; some carburizing and slow cooled parts often are reheated in selected areas by induction heating. Typical applications include: l
l
l
Medium-carbon steels, such as 1030 and 1045, for parts such as auto driveshafts and gears High-carbon steels, such as 1070, for parts such as drill and rock bits and hand tools Alloy steels for such parts as bearings, valves, and machine tool parts
Reference I. ASM Metals Handbook. Heat Treating, Vol 4. 10th ed., ASM lntemational.
1991, p 164
Hardening
In this process, a thin surface shell of a steel part is heated rapidly to a temperature above the critical point of the steel. After the structure of the shell becomes austenitic, the part is quenched quickly, transforming the austenite to martensite. The quench must be fast enough to bypass the pearlite and bainite phases. In some applications, self-quenching and selftempering are possible, Ref I. (See articles on other self-quenching processes-electron beam, laser, and high frequency, pulse hardening-elsewhere in this chapter.)
Characteristics Hardening is obtained by direct impingement of a high-temperature flame or by high-velocity combustion product gases. The flame is produced by the combustion of a mixture of fuel gas and oxygen or oil. The mixture is burned in flame heads: depth of hardness ranges from approximately 0.8 to 6.4 mm (0.03 125 to 0.25 in.), depending on the fuels used,
design of the flame head, duration of heating, hardenability of the workpiece, the quenching medium, and quenching method. Flame hardening differs from true case hardening in that hardness is obtained by localized heating. The process generally is selected for wear resistance provided by high levels of hardness. Other available gains include improvements in bending properties, torsional strength, and fatigue life. Comparative benefits of flame hardening, induction hardening, nitriding, carbonitriding. and carburizing are summarized in an adjoining Table.
Operating
Information
Methods of flame hardening include these types: spot (or stationary), progressive, spinning, and combination progressive-spinning. Spot and progressive spinning are depicted in a Figure, spinning methods in a second Figure.
Guidelines
for the Heat Treatment
of Steel / 43
Fuel Gases Used for Flame Hardening usual Beatingvalue Gas Acetylene City gas Natural gas (methane) Propane MAPP
MJ/m’
Bhr/ft’
53.4 1433 I I .2-33.5 300900 37.3 loo0 93.9 90
2520 2406
Ftarne temperature With oxygen With air OF OC OC OF
nltioof oxygen to fuel gas
Beating value of oxy-fuel gas mixture hfJjtn’ Bhr/ftJ
Notmal velocity of buruiug mm/s i0.p
Combustion intensity(a) mm/sx tn./s x I\lJ/m’ Btu/ftJ
USUd ratio of
airI0 fuel gas
3105 2540 2705
5620 4600 4900
2325 1985 1875
4215 3605 3405
I.0 (b) I .75
26.1 (hi 13.6
716 (b) 364
535 (b) 280
II (b) II
I4 284 (b) 3808
15 036 (W 4004
12 W 9.0
2635 2927
477s 5301
192s 1760
3495 3200
4.0 3.5
18.8 20.0
504 53s
30s 381
I2 I5
5 734 7 620
6oJ8 8025
25.0 22
(a) Product of normal velocity of burning multiplied by heating value of oxy-fuel gas mixture. (b) Varies with heating value and composition
Procedure
for Spin Flame Hardening
the Small Converter
Preliminary operation Turn on water, air, oxygen, power, and propane. Line pressures: water, 220 kPa (32 psi); air. 550 kPa (80 psi); oxygen, 825 kPa ( 120 psi); propane. 20.5kPa (30 psi). Ignite pilots. Loading and positioning Mount hub on spindle. Hub is held in position by magnets. Flame head pm\ iously centered in hub within 0.4 mm (‘1~ in.). Distance front flame head to inside diameter of gear teeth, approximately 7.9 mm &te in.) Cycle start Spindle with hub advances over flame head and starts to rotate. Spindle speed. I-10 rpm Beating cycle Propane and oxygen solenoid valves open (oxygen flow delayed slightly). Mixture of propane and oxygen ignited at flame head by pilots. Check propane and oxygen gages for proper pressure. Adjust flame by regulating propane. Heating cycle controlled by timer. Tune ptedetemtined to obtain specified hardening depth
Shallow hardness patterns of less than 3.2 mm (0.125 in.) deep can be obtained only with oxy-gas fuels. When specified hardnesses are deeper, oxy-fuels or air-gas fuels may be used. Time-temperature depth relationships for various fuel gases used in the spot (stationary), spinning, and progressive methods are shown in an adjoining Figure. Burners and Related Equipment. Burners vary in design, depending on whether oxy-fuel or air-fuel gas mixtures are used. Flame temperatures of the air-fuel mixtures are considerably lower than those of oxy-fuel mixtures (see Table). Flame heads for oxy-fuel gas are illustrated in an adjoining Figure, while those for air-fuel gas are shown in a second Figure. Operating Procedures and Control. The success of many applications depends largely on the skill of the operator. Procedures for two applications are summarized in adjoining tables. Preheating. Difficulties in getting the required surface hardness and hardness penetration in treating parts large in cross section often can be overcome by preheating. When available power or heat input is limited, depth of hardness can also be increased by preheating. Results in one application are shown in an adjoining Figure. Quenching Methods and Equipment. Method and type of quenchant vary with the flame hardening method used. hnrnersion quenching generally is the choice in spot hardening, but spray quenching is an alternative. In quenching after progressive heating, the spray used is integrated into the flame head. However, for steels high in hardenability, a separate spray-quench sometimes is used. Parts heated by the spinning method are quenched several ways. In one, for example, the heated part is
Gear Hub Beating cycle (continued) Propane and oxygen solenoid valves close (propane flow delayed slightly). Spindle stops rotating and retracts. Hub stripped from spindle by ejector plate. Machine ready for recycling Propane regulated pressure, I25 kPa ( I8 psi ); oxygen regulated pressure, 550 kPa (80 psi); oxygen upstream pressure, ux) kPa (58 psi); oxygen downstream pressure, I40 kPa (20 psi). flame velocity (ap roximate), I35 m/s (450 ft/s). Gas consum tions (approximate); propane, 0.02 rn.7 (0.6 fts) per piece: oxygen, 0.05 m3 ( I .9 ft ) per piece. Total heating time, 95 s Flame pan design: I2 ports per segment; IO segments; port size, No. 69 (0.74 mm. or 0.0292in.).withNo.56(1.2mm,orO.O46Sin.)counterbore
f
Quench cycle Hubdrops into quench oil, is removed from tank by conveyor. Oil temperatute. S4f 5.6 “C (130-t IO “F); time in oil (approximate), 30s Eardoess and pattern aim Hardness, 52 HRC minimum to a depth of 0.9 mm (0.035 in.) maximum above toot of gear teeth
Relative
Benefits
carburizing
Carbonitriding
Nitriding
induction hardening
Flame hardening
of Five Hardening
Processes
Hard. highly wear-resistant surface (medium case depths); excellent capacity for contact load; good bending fatigue strength; good resistance to seizure; excellent freedom from quench cracking; low-to-medium-cost steels required; high capital investment required Hard, highly wear-resistant surface (shallow case depths): fair capacity for contact load; good bending fatigue strength: good resistance to seizure; good dimensional control possible; excellent freedom Fromquench cracking; low-cost steels usually satisfactory; medium capital investment required Hard. highly we=-resistant surface (shallow case depths); fair capacity for contact load; good bending fatigue strength;excellent resistance toseizure; excellent dimensional control possible; good 6eedom Fromquench cracking (during pretreatment): medium-to-high-cost steels requited; medium capital investment required Hard. highly wear-resistant surface (deepcase depths); good capacity for contact load; good bending fatigue strength; fair resistance to seizure; fair dimensional control possible: fair freedom from quench cracking; low-cost steels usually satisfactory; medium capita) investment required Hard, highly wear-resistant surface (deepcase depths); good capaci3 for contact load; good bending fatigue strength; fair reststance to seizure; fair dimensional control possible; fair freedom from quench c73cking; low-cost steels usually satisfactory; low capital investment requited
44 / Heat Treater’s
Guide
Spot (stationary) and progressive methods of flame hardening. (a) Spot (stationary) internal lobes of a cam; quench not shown. (b) Progressive hardening method
Spinning methods Quench not shown
Response
of flame hardening.
In methods shown at left and at center, the part rotates. In method at right, the flame head rotates.
of Steels and Cast Irons to Flame Hardening
hlaterial Plain carbon steels 1025-1035 I043 IO.50 10.55-1075 1080-1095 11’5-1137 ll38-114-l 114&1151
Qpical hardness, EIRC, as affected by quenchant Air(a) Oil(b) Water(b)
SO-60 55-62
92-58 58-62 S8-62
15-55 SO-55
52-57(C) s5-60
33-50 55-60 60-63 62-65 AS-55 55-62 58-61
58-62 60-63
62-65 62-65
52-57(C) 55-60 58-62 61-63 SO-55 52-56 58-62 53-57 56-60 52-56
S-62 60-6-I 63-65 63-65 55-60 55-60 62-65 60-63 62-6s 60-63
Carburized grades of plain carbon steels(d) SO-60 1010-1020 50-60 1108-1120 Alloy steels 13-u)-1335 3110-3115 3350 4063 4130-413s 4l40-4I-15 11-17~1150 13374340 4347 -I640
method of flame hardening a rocker arm and the
35-55 50-60 55-60
55-60 52-56 M-62 53-57 56-60 52-56
‘l)pical hardness, EIRC, as affected by quenchant Air(a) Water(b) oil(b)
hiaterial Allo] steels (continued) 52100 6150 8630-8640 86x-8660
M-60 48-53 55-63
Carburized 3310 461.54620 86 I S-8620
grades of alloy steels(d) 55-60 58-62
hlsrtensitic -llO.-tl6 -II-l1131 120 UOttvpical) .
stainless steels
55-60 5260 52-57 55-63
62-64 Xi-60 58-62 62-64
58-62 62-65 58-6’
63-65 64-66 62-65
-11-l-I G-47 -t9-56 55-59
41-U 12-47 49-56 55-59
Cast irons (ASThI classes) Class 30 class 40 Class-!5010 s0007.53004.6lmJ3 Class 80002 52-56 class &l-45- IS
43-48 -18-52 3543 52-56 56-59
43-18 38-52 35-45 55-60 X1-61 35-45
ta)Toobtainthe hardnessresultsindicated. thoseareasnotdirectly heatedmust be kept relativelycoolduring the heatingprocess.~b)Thinxctionsaresusceptible~ocracking when quenched with oil or water. (c) Hardness is slightly lo\rer for material heated by spinning orcombination progressive-spinning methods than it is for material heated by progressive or stationary methods, td) Hardness values of carburized cases containing 0.90 IO I. 10% C
Guidelines
Calculated time-temperature-depth ness given in millimeters
relationships
Typical
gas. (a) Radiant type. (b) High-velocity
burners
for use with air-fuel
for spot (stationary),
spinning,
for the Heat Treatment
and progressive
convection
flame hardening.
type (not water cooled)
of Steel
/ 45
Depth of hard-
46 / Heat Treater’s
Guide
Flame heads for use with oxy-fuel gas
Effect of preheating on hardness gradient in a ring gear
Progressive
Flame Hardening
of Ring Gear Teeth
Workpkxe Bevel ring gear made of 87-12 steel with 90 teeth. Diametral mm (8 in.); outside diameter, I.53 m (60.112 in.)
pitch, 1.5; face width. 200
hlouoting Gear mounted on holding fixture to within 0.25 mm (0.010 in.) total indicator runout Flame beads ILvo IO hole. double-row. air-cooled flame heads. one on each side of tooth. Flame heads set 3.2 mm (‘/s in.) 6om tooth Operating
removed tank.
from the heating area and quenched
by immersion
conditions
Go.sp~ssurps. Acetylene, 69 kPa ( IO psi); oxygen. 97 kPa ( I4 psi) Speed. I .9 mm/s (4.5 in./min). Complete qcle (hardening pass, overtravel at each end, index rime. preheat return stroke on next tooth), 2.75 min hdering. Index every other tooth. index four times before immening in coolant. Coolanr. Mixture of soluble oil and hater. at I3 “C (55 “Fj Hardnessaim. 53 to 55 HRC
in a separate
Quenching Media. Water, dilute polymer solutions, and brine solutions are used. Oils are not: they should not be allowed to come into contact with oxygen, or to contaminate equipment. In many types of flame hardening (excluding through hardening) selfquenching speeds up cooling. The mass of cold metal underneath the heated layer withdraws heat, so cooling rates are high compared with those in conventional quenching. During progressive hardening of gear teeth made of medium-carbon steels, such as 4140, 4150. 4340, and 4610, for instance, the combination of rapid heating and the temperature gradient between the surface and interior of a gear results in a selfquench. Results are similar to those obtained with oil. Tempering. Flame hardened parts usually are tempered, with parts responding as they do when they are hardened by other methods. Standard procedures, equipment, and temperatures may be used. If parts are too large to be treated in a furnace. they can be Hame tempered. Also, large parts hardened to depths of about 6.4 mm (0.25 in.) can be self-tempered by
residual heat in the part: hardening stresses are relieved separate operation may not be necessary.
and tempering
in a
Applications flame hardened plain carbon steels, carburized grades of plain carbon steels, alloy steels, martensitic stainless steels, and cast irons that are flame hardened are listed in an adjoining Table.
Reference I. ASM Merals Handbook tional, 1991, p 368
Hear Treating, Vol 4. 10th ed., ASM lntema-
Gas Carburizing In this process, carbon temperatures required to carbon steels. Austenite quenching and tempering,
is dissolved in the surface layers of parts at the produced an austenitic microstructure in lowis subsequently converted to martensite by Ref I.
Characteristics This is the most important carburizing process commercially. The gradient in carbon content below the surface of a part produced in the process causes a gradient in hardness; resulting surface layers are strong and resistant to wear. The source ofcarbon is a carbon-rich furnace atmosphere,
including gaseous hydrocarbons, such as methane, propane, and butane, or vaporized hydrocarbon liquids. Lou-carbon steels exposed to these atmospheres carburize at temperatures of 850 “C (I 560 “F) and above.
Operating
Information
In present practice, for two reasons: l
carbon content in furnace atmospheres
To hold tinal carbon concentration solubility limit in austenite
is controlled
at the surface of parts below
the
Guidelines
Plot of total case depth versus
l
To minimize
carburizing
time at four selected
071 ‘C IMOO ‘FI
.899T116M’F1
l
927 ‘C 11700 ‘FI
in.
mm
in.
“Ill
in.
mm
in.
I , ;
0.46 0.64 0.89
0.018 0.035 0.03
0.53 0.76 1.07
0.02 I 0.0-P 0.030
0.6-I 0.89 I.27
O.OY 0 050 0.035
0.‘4 I.04 I.30
0.029 0.051 I 0.04
8 I? I6 .?4 30
I.27 I.55 1.80 2.18 2.46
0.050 0.061 0.071 0.086 0.097
I.52 18.5 2.13 2.62 2.95
0.060 0.073 oon4 0.103 0.116
I.80 2.21 ?..(-I 3.10 3 -In
0.07 I 0.087 0.100 0.1’2 O.li?
2.11 2 59 2.9: 3.M 4.09
0.083 O.lO! 0.117
Residual stresses put into parts prior to heat treating Shape changes caused by heating too rapidly
/ 47
951 ‘C 11750 “FI
mm
sooting of the furnace atmosphere
of Steel
Graph based on data in table
Time. h
Endothermic gas, the usual carrier, plays a dual role: it acts as a diluent and accelerates the carbutizing reaction at the surface of parts. Parts, trays, and fixtures should be thoroughly cleaned before they are charged into the furnace-often in hot alkaline solutions. In some shops, these furnace components are heated to 400 “C (750 “F) before carburizing to remove traces of organic contaminants. Key process variahles are temperature, time, and composition of the atmosphere. Other variables are degree of atmosphere circulation and the alloy content of parts. Temperature. The rate of diffusion of carbon in austenite determines the maximum rate at which carbon can be added to steel. The rate increases significantly with increasing temperature. The rate of carbon addition at 925 “C (1695 “F) is about 40 percent higher than it is at 870 “C (1600 “F). At this temperature, the carburizing rate is reasonahly rapid and the deterioration of furnace components, especially alloy trays and futtures, is not excessive. When deep cases are specified, temperatures as high as 966 “C (1770 “F) sometimes are used to shorten carburizing times. For consistent results, temperatures must be uniform throughout the workload. The desired result can be obtained, for example, with continuous furnaces with separate preheat chambers. Time. The combined effect of time and temperature on total case depth is shown in an adjoining Figure. The relationship of carburizing tune and increasing carburizing temperature is shown in a second Figure. Dimensional Control. To keep heat-treating times as short as possible, parts should be as close to final dimensions as possible. A number of other factors also have an influence on distortion, including: l
temperatures.
for the Heat Treatment
0.I.t.l 0 Ihl
Reducing effect of increased process temperature on carburizing time for 8620 steel. Case depth: 1.5 mm (0.060 in.)
Properties
of Air-Combustible
Gas Mixtures
Autoignition temperahwe
Flammable limits in
Gas
OC
OF
Methane Propane Hydrogen Carbon mono.tiurde Methaool
S-IO 466 -mo
100s
5.1IS
870 750 1130 72s
2.19,s 4.0-7s 12.5-74 6.7-36
609 385
air, vol %
48 / Heat Treater’s
Guide
Plot of stress relief versus tempering temperatures held for 1 h for two carbon concentrations in austenite
A high-productivity
l
l
The manner in which quenching Severity of quenching
A pit batch carburizing furnace. Dashed lines outline location of workload.
gas-fired integral quench furnace
parts are stacked or fixturcd
in carburizing
and
Quenchants include brine or caustic solutions, aqueous polymers, oils, and molten salt. In some industries, parts are carburized at 917 “C (I 700 “F) or above, cooled slowly to ambient temperature. then reheated at 843 “C (I 550 “F), then quenched. Benefits include refinement in microstructure and limiting the amount of retained austenite in the case.
Tempering. Density changes during tempering affect the relief of residual stresses produced in carburizing. An adjoining Figure shows the effect of tempering for I h at various temperatures on stress relief. Stress relief occurs at lower tempering temperatures as the amount of carbon dissolved in austenite is increased. Selective Carburizing. Some gears, for example, are carburized only on teeth, splines, and bearing surfaces. Stopoffs include copper plating and ceramic coatings. Safety Precautions. The atmospheres used are highly toxic and highly inflammable. When combined with air, explosive gas mixtures are
Guidelines
Relation Between Dew Point and Moisture Content of Gases. Hydrogen can be purified by a room-temperature catalytic reaction that combines oxygen with hydrogen, forming water. Then, all water vapor is removed by drying to a dew point of -60 “F (-51 “C).
Composition Steel
of Carburizing C
Mn
for the Heat Treatment
of Steel / 49
Iron Oxides from CO, or H,O. Data point 1: an atmosphere consisting of 75 H, and 25 H,O will reduce scale on iron (Fe0 or Fe,O,) at 1400 “F (760 “C). Data point 2: same atmosphere will scale metal at 900 “F (480 “C)
Steels Composition, Q Ni Cr
MO
Other
Carbon steels 1010 1019 1018
0.08-0.13 0.30-0.60 0.15-0.20 0.70-1.00 0.60-0.90
. ...
.. . .
.. .. .
i”? IZ $ ;;;
1020 1021
0.18-0.23
0.30-0.60 0.60-0.90
..
. ..
. ..
$1: y;
1022 1524 1527
0.18-0.23 0.19-0.25 0.22-0.29
0.70-1.00 1.35-1.65 1.20-1.50
... .
... ..
. ..
(:I: (b) (4, (b)
Resulfurized steels 1117 0.14-0.20
1.00-1.30
..
.. .
..
0.08-O. 13 S
Alloy steels 3310 0.08-0.13 4023 0.20-0.25 4027 0.25-0.30 4118 0.18-0.23 4320 0.17-0.22 4620 0.17-0.22 4815 0.13-0.18 4820 0.18-0.23 5120 0.17-0.22 5130 0.28-0.33 8617 0.15-0.20 8620 0.18-0.23 8720 0.18-0.23 8822 0.20-0.25 9310 0.08-0.13
0.45-0.60 0.70-0.90 0.70-0.90 0.70-0.90 0.45-0.65 0.45-0.65 0.40-0.60 0.50-0.70 0.70-0.90 0.70-0.90 0.70-0.90 0.70-0.90 0.70-0.90 0.75-1.00 0.45-0.65
3.25-3.75 1.40-1.75 ... . . . 0.40-0.60 1.65-2.00 0.40-0.60 1.65-2.00 3.25-3.75 3.25-3.75 0.70-0.90 0.80-1.10 0.40-0.70 0.40-0.60 0.40-0.70 0.40-0.60 0.40-0.70 0.40-0.60 0.40-0.70 0.40-0.60 3.00-3.50 1.00-1.40
0.40-0.70 0.40-0.60
2.75-3.25
0.35
2.00
Special alloys CBS-600 0.16-0.22 CBS0.10-0.16 1OOOM Alloy 53
0.10
(a)0.004Pmax,0.05
Smax.(b)0.15-0.35Si.
... 0.15-0.25 0.15-0.25 0.20-0.30 0.30-0.40 0.08-0.15
1.25-1.65 0.90-1.10 0.90-1.20 4.00-5.00 1.00
(b)> Cc) (b). Cc) (b), Cc) (b). Cc) (b)> Cc) (b). Cc) (b). (cl (b), (cl (b). Cc) (b), (c) (b). Cc) (b)> Cc) (b), Cc) (b)> Cc) (b), Cc)
0.20-0.30 0.20-0.30 0.08-0.15 0.20-0.30 0.20-0.30 0.20-0.30 0.20-0.30
3.25
0.90-1.25 Si 0.40-0.6OSi 0.15-0.25 V 1.OOSi, 2.00 cu,o.1ov
(c)O.035 Pmax,O.O4Smax
Available Carbon (the Weight of Carbon Obtained for Carburizing from a Given Gas at a Given Temperature). Charcoal gas analyzes 20 CO, 80 N,. Natural gas is principally methane. Data point 1: at 1700 “F (925 “C), the available carbon in charcoal gas is 0.0000272 lb/k3 (0.004357 kg/m3). Data point 2: in natural gas, there is 1200 times as much or 0.0337 IbW (0.5398 kg/ma)
50 / Heat Treater’s
formed. Properties ing Table.
Guide
of air-combustible
gas mixtures
are given in an adjoin-
Water Gas Reaction, CO + H,O CJ CO, + H,. Variation of equilibrium constant K with temperature. K is independent of pressure, since there is no volume change in this reaction.
Carburizing Equipment. Both batch and continuous furnaces are used. Among batch types, pit and horizontal furnaces are the most common in service. A pit furnace is illustrated in an adjoining Figure. Adisadvantage of the pit type is that when parts are direct quenched, they must be moved in air to the quenching equipment. The adherent black scale developed on parts with this practice may have to be removed by shot blasting or acid pickling. Horizontal batch furnaces with integral quenching facilities are an alternative (see Figure). Continuous furnaces used in carburizing include mesh belt, shaker hearth. rotary retort, rotary hearth, roller hearth, and pusher types.
Compositions Carbon steel, resulfurized In an adjoining Table.
steel, and alloy steel compositions
are listed
Reference I. ASM Metals Handbook, Hear Treating, Vol 4, 10th ed., ASM Intemational,
Pack
1991, p 312
Carburizing Operating
Information
In this process, carbon monoxide derived from a solid compound decomposes at the metal surface into nascent carbon and carbon dioxide. Carbon is absorbed into the metal; carbon dioxide immediately reacts with carbonaceous material in the solid carburizing compound to produce fresh carbon monoxide. Carbon monoxide formation is enhanced by energizers or catalysts such as barium carbonate, calcium carbonate, potassium carbonate, and sodium carbonate present in the carburizing compound. Energizers facilitate the reduction ofcarbon dioxide with carbon to form carbon monoxide, Ref I
The common commercial carburizing compounds are reusable and contain IO to 20 percent alkali or alkaline earth metal carbonates bound to hardwood charcoal, or to coke by oil, tar, or molasses. Barium carbonate is the chief energizer, usually accounting for 50 to 70 percent of total carbonate content. Process Control. Two parameters are unique to the process:
Characteristics
l
Both gas carburizing and liquid carburizing have labor cost advantages over this process. This disadvantage may be offset in jobs requiring additional steps, such as cleaning and the application of protective coatings in carburizing stopoff operations. Other considerations favor pack carburizing: A wide variety of furnaces may be used because the process produces its own contained environment l It is ideally suited for slow cooling from the carburizing temperature l It offers a wider selection of stopoff techniques than gas carburizing for selective carburizing techniques On the other side of the ledger, pack carburizing is less clean and less convenient to use than the other carburizing processes. In addition:
l
Case depth may vary within a given furnace due to dissimilar thermal histories within the carburizing containers Distortion of parts during carburizing may be reduced because compound can be used to support workpieces
Carbon potential of the atmosphere generated by the compound, as well as the carbon content obtained at the surface of the work, increase directly with an increase in the ratio of carbon monoxide to carbon dioxide.
l
l
l l
l
It isn’t well suited for shallow case depths where depth tolerances are strict It is labor intensive It takes more processing time than gas or liquid carburizing because of the heating time and cooling time required by the extra thermal mass associated with the solid carburizing compound and the metal container used It isn’t suited for direct quenching or quenching in dies
Effect of time on case depth at 925 “C (1700 “F)
Guidelines
Typical Applications
for the Heat Treatment
of Steel / 51
of Pack Carburizing CprbUIiZiIlg Dimensions(a) OD
Pall Mine-loader bevel gear flying-shear timing gear Crane-cable drum HigIl-misaligNnent coupting gear Continuous-miner drive pinion Heavy-duty ir~Iustrial gear Motor-brake wheel l-Qll-performance crane wheel Calender bull gear Kiln-uunnion roller Leveler roll Blooming-mill screw Heavyduty rotting-mill gear Prccessor pinch roU
OA
mm
in.
102 216 603 305 I27 618 457 660 2159 762 95 381 914 229
4.0 8.5 23.7 12.0 5.0 24.3 18.0 26.0 85.0 30.0 3.7 IS.0 36.0 9.0
mm
Weight in.
76 92 2565 152 I27 I02 215
3.0 3.6 101.0 6.0 5.0 4.0 8.9 6.0 24.0 16.0 31.3 131.0 159.0 212.0
I.52 610
406 794 3327 4038 5385
kg I.4 23.6 1792 38.5 5.4 IS0 IO4 335 5885 1035 36.7 2950 II 800 1700
lb 3.1 52.0 3950 84.9 II.9 331 229 739 I2975 2’80 80.9 6505 26015 3750
Steel 2317 2317 I020 46617 2317 I022 10’0 103s 1025 1030 3115 311s 2325 8620
Case depth to 50 ERC mm in. 0.6 0.9 I.2 I.2 I.8 I.8 3.0 3.8
4.0 4.0 4.0 5.0 5.6 6.9
0.02-I 0.036 0.048 0.048 0.072 0.072 0.120 0.150 0.160 0.160 0.160 0.200 0.220 0.270
Temperahue OF T
925
1700 I650 I750 I700 1700 I725 1700 1725 I750 I725 1700 1700 1750 I925
900 955 925 925 940 925 940 955 940 925 925 955 1050
(a) OD, outside diameter; OA, overall (axial) dimension
Operating temperatures normally run from 815 to 955 “C ( 1500 10 1750 “F). However, temperatures as high as 1095 “C (2005 “F) are used. The rate of change in case. depth at a given temperature is proportional to the square root of time. This means the rate of carburization is highest at the beginning of the cycle and gradually diminishes as the cycle continues. Case Depth. Even with good process control, it is difficult to hold case depth variation below 0.25 mm (0.010 in.) from maximum to minimum in a given furnace load, assuming a carburizing temperature of 925 “C (1695 “F). The effect of time on case depth is shown in an adjoining Figure. Furnaces are commonly of the box, car bottom, and pit types. Temperature uniformity must be controllable within &5 “C (+99 “F). Containers normally are made of carbon steel, aluminum coated carbon steel, or iron-nickel-chromium, heat-resisting alloys.
Liquid
Carburizing
and Properties
and workpiece is not provides good support
Applications
Reference I. ASM Metals Hundbook. Hear Treating, Vol 4, 10th ed.. ASM Intemational, 1991, p 325
and Cyaniding
Both are salt bath processes. In liquid carburizing. cyanide or noncyanide salt baths are used. Cyaniding is a liquid carbonitriding process. 11differs horn liquid carburizing because it requires a higher percentage of cyanide and the composition of the case produced is different. Cases produced in the carburizing process are lower in nitrogen and higher in carbon than cases produced in cyaniding. Cyanide cases are seldom deeper than 0.25 mm (0.010 in.); carburizing cases can be as deep as 6.35 mm (0.250 in.). For very thin cases, low-temperature liquid carburizing baths may be used in place of cyaniding, Ref I.
Compositions
Packing. Intimate contact between compound necessary, but with proper packing the compound for workpieces.
of Sodium
Cyanide
Liquid carburizing. Parts are held at a temperature above Act in a molten salt that introduces carbon and nitrogen, or carbon, into the metal being treated. Diffusion of the carbon from the surface toward the interior produces a case that can be hardened, usually by fast quenching, from the bath. Cyaniding. In this process, steel is heated above Act in a bath containing alkali cyanides and cyanates, and its surfaces absorb both carbon and nitrogen from the molten bath.
Mixtures specificgravity
ktktwegrade designation
NaCN
%98(a) 75(b) 45(b) 30(b)
97 75 45.3 30.0
Composition,w(% NaCOJ
Melting point NaCl
OC
OF
2.3 3.5 37.0 40.0
Trace ‘I.5 17.7 30.0
560 590 570 625
ICUI 1095 1060 115s
25oc (75W I.50 I .60 I.80 2.09
I.10 I .25 I.40 I.54
(a) Appearance: white crystalline solid. This grade contains 0.5%, sodium cyanate (NaNCO) and 0.X. sodium hydroxide (NaOH); sodium sulfide (Na,S) content. nil. (b) Appearance: white granular mixture
52 / Heat Treater’s
Typical Applications
Guide
of Liquid
Carburizing
Weight Part
In Cyanide
Baths
Depth of case mm in.
Temperature OC OF
Steel
Disk Flange Gage rings, knurled Hold-down block hen. tapered Lcwr Link Plate Plug Plug gage Radius-cutout toll Torsion-barcap
0.9 0.5 0.7 3.5 I.1 I.1 0.03 0.09 0.9 4.75 0.05 0.007 0.007 0.7 O.-IS 7.7 0.05
2 I.1 I5 7.7 2.5 3 0.06 0.2 2 IO.5 0.12 0.015 0.015 1.6 I I7 0. I
CR 1020 CR 1020 CR I020 1020 1020 CR 1020 1020 1018 IO10 CR 10’0 CR IO’2
I.0 IS I.5 1.3 1.3 I.3 0.4-0.5 I5 I.0 1.3 0.13-0.2s 0 13-0.2s 0 ‘S-O.-l I.5 I .s I .s 0.02-0.05
0.040 0.060 0.060 0.050 0 050 0.050 0.0 I s-0.020 0.060 0.040 0.050 0.005-0.010 0005-0010 0.010-0.015 0.060 0.060 0.060 0.001-0.002
940 9-10 9-lO 9-h) 940 9-10 815 9-10 9-10 9-to a-15 8-15 8-e 9.40 9-10 910 900
I720 I720 I720 I720 I720 I720 I550 I720 I720 I720 1550 1550 1550 I720 I720 I720 I650
4 6.5 6.5 5 5 5 -I 6.5 4 5 I I 2 6.5 6.5 6.5 0.12
AC AC AC AC AC (h) Oil AC AC AC Oil AC Oil AC AC AC Caustic
(a) (a) (a) (a) (a) (b) (C) (a)
Resulfurized steel Bushing Dash sleeve Disk Drive shah Guide bushing Nut Pm
0.01 3.6 0.0009 3.6 0.1 0.0-I 0.003
0.09 8 0.002 8 OS 0.09 0.007
III8 III7 III8 III7 III7 III3 III9
0.25-0.-l I.1 0.13-0.2s I.1 0.75 0.13-0.2s 0.13-0.25
0.010-0015 0.015 00050.010 0.045 0.030 0.005-0.010 0.009-0.010
815 915 81s 91.5 915 84.5 8-15
I550 I675 1550 1679 1675 IS50 1550
7 7 I 7 5 I I
Plug Rack Roller screw Shah Spring seat slop collar Stud Valve bushing Valve retainer Washer
0.007 0.31 0.0 I 0.003 0.08 0.009 0.9 0.007 0.02 0.15 0.007
0.015 0.75 0.03 0.007 0.18 0.02 2 0.015 0.05 I 0.015
III3 III3 1118 III3 III8 III8 1117 1118 III7 1117 III8
0.075-o. I3 0.13-0.2s 0.25-0.1 0.0750. I3 0.25-0.-l 0.2.5-0.4 I.1 0.13-0.2s 1.3 I.1 0.25-0.-l
0.003-0.005 0.0050.010 0.0 I o-0.0 IS 0 003-0.00.5 0.0 I o-0.0 I s 0.010-0.015 0.045 0.0050.0I0 0.050 0.045 0.0 I O-O.0IS
815 U-15 845 x-15 845 81s 925 x-l.5 915 915 a-15
I sso I550 IS50 1550 I550 I.550 1700 1550 1675 1675 ISSO
0.9-36 0.20 0.03 0.9 0.31 0.03 O.-IS 4.586 0.20 0.15-82 2.3-23 0.0009 0.45-5-I 0.20 S.-l I.8 0.0 I 0.20 0.45-3.6
2-80 0.5 0.06 2 0.75 0.06 I IO-190 0.5 l-180 S-50 0.002 I-120 0.5 I’ -I 0.03 0.5 l-8
8620 8620 8620 8620 8620 8620 8620 8620 8620 8620 8620 9317 86’0 8620 86’0 8620 8620 8620 8620
2.3 2.3 0.25-0.4 I .o I .o 0.075cl. I3 0.75 I .5 1.3 I.3 I.1 0. I-O.2 I.3 I.1 ‘3 I .s 0.1-03 I.1 I3
0.090 0.090 0.0 I o-0.0 IS 0.040 0.040 0.003-0.005 0.030 0.060 0.050 0.050 0.045 0 00-l-0.008 0.050 0.045 0.090 0.060 0.01 s-o.020 0.045 0.050
9’5 925 8-15 915 915 8-15 915 9’9 915 91s 91.5 81s 925 915 925 915 84s 915 915
I700 I700 I.550 I675 I675 1550 I675 1700 I675 1675 1675 I s50 1700 I675 I 700 I675 IS50 I675 I675
Carbon steel Adaprcr Arbor. tapered BWJliflg Die block
Alloy steel Beating races Bearing rollers Couplmg Crankshaft Gear Idler shah Pintle Piston Plunger Ram Retainer Spool Thrust cup Thrust plate Universal socket Valte valve seat Wear plate
Tie,
h
Quench
Subsequent treatment
lb
kg
Eardnes., ERC
(a) (a) (c)
62-63 62-63 62-63 62-63 59-61 56-57 55 mitt(d) 62-63 62-63 62-63 W
(C) (a) (a) (a) (0
(e) 62-63 62-63 62-63 45-47
Oil AC Brine AC (j) Oil Oil
(d (iit) Cc) (h)
Cd 58-63 (e) 58-63 58-63 W (e)
0.5 I 7 OS 2 2 6.5 I 8 7 2
Oil Oil Oil Oil Oil Oil AC Oil AC ci) Oil
(CJ w (C) (C) Cc) (C) (I?) (c) (8)
II II 2 6.5 6 0.5 5 I’
AC AC Oil AC AC Oil (i) tit AC (ii (ij Oil ti) tit AC AC Oil AC AC
(is) (I3
8
8 7 0.33 7 7 I-l IO -I 7 7
w (C)
(c)
IL; w (c)
(8
ti)
(P) $ (ia (8)
1:; l:; W (e) 60-63 k) 58-63 58-63 (e) 61-64 61-64 (e) 60-63 60-63 (e) 58-63 58-63 60-63 58-63 58-63 (a 58-63 58-63 60-6-I 58-63 60 mm(d) 60-63 60-63
(a) Reheatedat79O”C( 1150”F),quenched incaustic. temperedat 150”C(30O”F~. tb~Transferrrd~o neutralsalt at 79O’C( 1450°F).qurnchedincaustic, temperedat I75 “C(350 “F). (c)Tempered at I65 “C (325 “Ft. (d) Or equivalent. te) File-hard. (0 Tempered at 205 “C (400 “F). tg) Reheated at 8-U OC( I SSO“FJ. quenched in salt al I75 “C (350 “F). (h) Reheatedat775”C( 1325”F).quenched insaltat 19S”Ct380°Ft.(i)Quencheddirectl~ insaltar 17S”Ct3SO”Ft.tj)Temprredat 16s 0C~3250F)andtreatedat-850C(-1300Ft
Guidelines
Liquid
Operating
Carburizing
Characteristics The case produced is comparable to one obtained in gas carburizing in an atmosphere containing some ammonia. In addition, cycle times are shorter because heat up is faster, due to the excellent heat transfer characteristics of the salt bath solution.
Operating
Information
Most of these baths contain cyanide. Both nitrogen and carbon are introduced into the case. A noncyanide process uses a special grade of carbon, rather than cyanide, as the source of carbon. These cases contain only carbon as the hardening agent. Low-temperature (for fight cases) and high-temperature (for deep cases), cyanide-containing carburizing baths are available. In addition to operating temperatures, cycle times can also be different. Low-Temperature Baths. Typical operating temperatures range from 845 to 900 “C (1555 to 1650 “F). Baths generally are of the accelerated cyanogen type. Operating compositions of liquid carburizing baths are listed in an adjoining Table. Baths usually are operated with a protective carbon cover. Cases that are 0. I3 to 0.25 mm (0.005 to 0.010 in,) deep contain substantial amounts of nitrogen. High-Temperature Baths. Operating temperatures usually are in the range of 900 to 955 “C (1650 to 1750 “F). Rapid carbon penetration may be obtained at operating temperatures between 980 and 1040 “C ( I795 to 1905 “F). Cases range from 0.5 to 3.0 mm (0.020 to 0. I20 in.) deep. The most important application of this process is for the rapid development of cases I to 2 mm (0.040 to 0.080 in.) deep. These baths contain cyanide and a major amount of barium chloride (see Tablej.
Applications Typical applications an adjoining Table.
of liquid carburizing
Noncyanide
Liquid
in cyanide
baths are listed in
Carburizing
A specirll grade of carbon is used in place of cyanide as the source for carbon. Carbon particles are dispersed in the molten salt by mechanical agitation with one or more simple propeller stirrers. The chemical reaction is thought to be adsorption of carbon monoxide on carbon particles. Carbon monoxide is generated by a reaction between carbon and carbonates in the salt bath. Carbon monoxide is presumed to react with steel surfaces in a manner similar to that in pack carburizing.
Operating
Information
Operating temperatures usually are higher than those for cyanide-type baths. The common range is about 900 to 955 “C ( I650 to I750 “F). Case depths and carbon gradients are in the same range as those for hightemperature, cyanide-type salts. Carbon content is slightly lower than that of standard carburizing baths containing cyanide.
Cyaniding Operating
(Liquid
Constituent
for the Heat Treatment
Compositions
of Liquid
of Steel / 53
Carburizing
Baths
Composition ofbath, % Light case, Deep case, low temperature high temperature 8.l~900°C (1550-16SO“F) 9oo-95S°C (16-W175oT)
IO-23 Sodiumcyanide 6-16 Barium chloride 30-55(a) Salts ofother alkaline O-IO O-IO earth met&t h) Potassium chloride O-25 O-20 Sodium chlonde ‘O-40 O-20 30 max Sodium carbonate 30 max Accelerators other than O-5 o-2 those in\olvingcompounds of alkaline earth metals(c) 0.5 milx Sodium cyanate I .Oniax Den.@ of molten salt I .76 g/crdat 900 “C tO.0636 2.00 gkm’at 92s “C (0.0723 Ih/in.‘at 1650°F) Ib/in.‘at 1700°F) (a) Proprietary barium chloride-free deep-case baths are available. (b) Calcium and strontium chlorides ha\e hecn employed. Calcium chloride is more effective, but its hyqoscopic nature has limited its use.(c) Among theseacceleratorsare manganesedioxtde. boron oxide, sodium fluoride, and sodium pyrophosphate.
Effect of Sodium Cyanide in 1020 Steel Bars
Concentration
on Case Depth
Samples are 25.4 mm diam (1 .O in. diam) bars that were cyanided minat815”C(1500”F). NaCN in bath, 96
mm
ill.
9-l.3 76.0 SO8 -13.0 30.2 20.8 15.1 10.8 52
0 IS 0.18 0.15 0.15 0.15 0.14 0.13 0.10 0.05
0.0060 0.0070 0.0060 0.0060 0.0060 0.0055 0.0050 0.0040 0.0020
30
Deptb of case
Faster carbon penetration is obtained by using operating temperatures above 950 “C (I 730 “Ft. Nancy anide baths are not adversely affected at this temperature because no cyanide is present to break down and cause carbon scum or frothing. Parts quenched after treatment contain less retained austenite than those quenched following cyanide carburization.
Carbonitriding)
Information
In this instance, sodium cyanide is used instead of the more espensive potassium cyanide. The active hardening agents (carbon monoxide and nitrogen) are produced directly from sodium cyanide.
A sodium cyanide mixture such as grade 30 (containing 30 percent NaCN, -IO percent Na2C.03. and 30 percent NaCI) generally is the choice for production applications (see Table shorn ing compositionsj. A 30 percent cyanide bath operating at 8 IS to 850 “C ( IS00 to IS60 “F) produces a 0. I3 mm (0.005 in.) case containing 0.65 percent carbon at the surface in
54 / Heat Treater’s
Guide
45 min. Similar
case depths can be obtained with sodium cyanide in treating 1020 steel. The effect of sodium cyanide on case depth in treating the steel is in an adjoining Table.
brine. The case contains less carbon and more nitrogen oped in liquid carburizing.
Applications
Reference
A fde hard, wear-resistant surface is produced on ferrous parts. The hard case is produced in quenching in mineral oil, paraffin-base oils, water, or
I. ASM Metals Handbook, Heat Treating, Vol4. tional. 1991, p 329
Vacuum
in a then
Characteristics Benefits of the process include:
l l
Excellent uniformity and repeatability due to the degree of process control inherent in the process Improved mechanical properties due to a lack of intergranular oxidation Reduced cycle times due to higher processing temperatures
A continuous
10th ed., ASM Intema-
Carburizing
In this process, steel is austenitized in a rough vacuum, carburized partial pressure of hydrocarbon gas, diffused in a rough vacuum, quenched in oil or gas, Ref I.
l
than those devel-
ceramic
vacuum-carburizing
furnace
Operating
Information
A continuous vacuum carburizing furnace is pictured in an adjoining Figure. Furnaces usually are designed for vacuum carburizing. with or without vacuum quenching capability. Controls and plumbing are modified to accommodate the process. Heat and Soak Step. Steel is fust heated to the desired carburizing temperature (typically in the range of 845 to 1040 “C (1555 to 1905 “F). Soaking follows at that temperature, but only long enough to get temperature uniformity throughout the part. In this step, surface oxidation must be prevented, and any surface oxides present must be reduced. In a graphite-lined heating chamber with graphite
Guidelines
for the Heat Treatment
Comparison of Time Required to Obtain a 0.9 mm (0.035 in.) and 1.3 mm (0.050 in.) Effective 8820 Steel at Carburizing Temperatures of 900 “C (1850 “F) and 1040 “C (1900 “F) Carburizing temperature
Effective depth mm in. 0.9
0.035
1.3
0.050
T 900 I040 900 1040
OF
lkatiog to carburizing temperature
1650 1900 1650 1900
78 90 78 90
smkiog prior to carburizing
Boost
45 30 45 30
Time, mio Gas quench toHoT Diffusion (ItWOoF)
101 1s 206 31
83 23 169 46
of Steel / 55
Case Depth in an AISI
Reheat to 845 oc (1550°F)
soak at 845T (155OV)
oil quench
Total
(a) 22 (a) 22
(a) 60 (a) 60
1s 1s 15 I5
>322 275 >s13 314
(3) 20 (Jo 20
(a) Not available
heating elements, for example, a rough vacuum in the range of 13 to 40 Pa (0. I to 0.3 torr) usually is satisfactory. Boost Step. The result here is carbon absorption by the austenite to the limit of carbon solubility in austenite at the processing temperature for the steel being treated. The operation in this instance is backfilling the vacuum chamber to a partial pressure with either a pure hydrocarbon gas, such as methane or propane, or a mixture of hydrocarbon gases. A minimum partial pressure of the gas is needed to ensure rapid carburizing of the austenite. Minimum partial pressure varies with carburizing temperature, gas composition, and furnace construction. ‘Qpical partial pressures vary between I .3 and 6.6 kPa ( IO to 50 torr) in furnaces of graphite construction and I3 to 25 kPa ( 100 to 200 [err) in furnaces of ceramic construction. Diffusion Step. In this instance, carbon is diffused inward from the carburized surface, resulting in a lower surface carbon content (relative to the limit of carbon solubility in austenite at the carburizing temperature) and a more gradual case/core transition. Diffusion usually is in a rough vacuum of 67 to I35 Pa (0.5 to I .O torr) at the carburizing temperature. Oil Quenching Step. Steel is directly quenched in oil, usually under a partial pressure of nitrogen. When temperatures are higher than those in conventional atmosphere carburizing. requirements usually call for cooling to a lower temperature and stabilizing at that temperature prior to quenching. If a reheating step is needed for grain refinement, the steel is gas quenched from the diffusion temperature to room temperature, usually under partial pressure of nitrogen. Reheating usually consists of austenitizing in the range of 790 to 845 “C (1455 to 1555 “F), followed by oil quenching.
Plasma
(Ion)
Characteristics The process has several advantages ing:
l l l l
l l
Gas Circulation.
For uniform
case depths the chief re-
are:
Temperature uniformity of +8 “C (fl4 “F) or better Uniform circulation of carburizing gas
High-Temperature
Vacuum
Carburizing
Typical atmosphere furnace construction generally limits maximum carburizing temperatures to about 955 “C (1750 “F). Vacuum furnaces permit higher carburizing temperatures, 14ith correspondingly reduced cycle times. The process can significantly reduce overall cycle times required to get effective case depths in excess of 0.9 to I .O mm (0.030 to 0.040 in.). There is no advantage for lower case depths. In an adjoining Table, the times needed to get 0.9 to I .O mm (0.030 to 0.040 in.) case depths with vacuum carburizing at 900 “C (I650 “F) and 1040 “C (1905 “F) for an AISI 8620 steel are compared.
Applications The process is well suited to process the more highly alloyed, highperformance grades of carburizing steels and the moderately alloyed grades being used. Gas pressure quenching in vacuum opens up opportunities for treating high-performance, low distortion gearing.
Reference I. ASM Metals Handbook, Hear Treating, Vol 4, 10th ed.. ASM tional, 1991. p 3-18
Intema-
Carburizing
This is basically a vacuum process utilizing glow discharge technology to introduce carbon bearing ions to steel surfaces for subsequent diffusion below the surfaces, Ref I.
l
Carburizing quirements
Higher carburizing rates Higher operating temperatures Improved case uniformity Blind hole penetration Insensitivity lo steel composition
over gas and atmosphere
carburiz-
Carburizing rates are higher because the process involves several steps in the dissociation process that produce active soluble carbon. With methane, for example, active carbon can be formed due to the ionizing effect of the plasma. Carburizing rates of plasma and atmosphere carburizing are compared in an adjoining Figure. Note that the results obtained in atrnosphere carburizing for 240 min at 900 “C (1650 “F) were obtained with the plasma process in half the time. In some applications, higher temperatures are permissible because the process takes place in an oxygen-free vacuum. Improvements in unifomlity of case depth in gear tooth profiles are shown in an adjoining Figure. Results obtained with the plasma process at 980 “C (I795 “F) and those obtained \sith atmosphere carburizing at the same temperature are compared.
56 / Heat Treater’s
Guide
Carbon concentration profiles in AISI 1020 steel after ion carburizing for 10,20,30,60, and 120 min at 900 “C (1650 “F). Carbon profile after atmosphere carburizing (1650 “F) shown for comparison
Production installation
for 240 min at 900 “C
Comparing uniformity of case depth over gear-tooth profiles. (a) Ion carbunked at 980 “C (1800 in a 980 “C (1800 “F) boost-diffuse its more consistency, particularly Courtesy of Surface Combustion,
“F). (b) Atmosphere carburized cycle. Case depth in (a) exhibin the root of the gear profile. Inc.
of two dual-chamber ion carburizing furnaces. Courtesy of Surface Combustion,
Inc.
Guidelines
Racked array of universal-joint Courtesy
components ready for ion carburizing. Two stacked
fixtures
for the Heat Treatment
constitute
one furnace
of Steel / 57
load of 1500 parts.
of Dana Corporation
Carbon concentration profiles in three carburizing steels after ion carburizing illustrating insensitivity to steel composition. Data are based on a boost-diffuse cycle of ion catburizing at 1040 “C (1900 “F) for 10 min followed 1000°C (1830°F).
by diffusion
for 30 min at
1
The ion carburizing rate for a given steel is quite insensitive to alloy composition, as shown in an adjoining Figure. The process is also insensitive to the hydrocarbon gas used as a source of carbon. A two-chamber ion carburizing furnace is shown in an adjoining Figure. As in other carburizing processes, time and temperature are the parameters that determine surface carbon and case depth. Temperature, and indirectly time, dcterrnine grain size and mechanical properties. Higher operation temperatures are used to speed up diffusion rates. After a time/temperature cycle is established, operating pressure is chosen, which can be any value. provided the plasma covers the parts and no hollow cathode effect is evident; a low pressure usually is chosen, in the range of 130 to 670 Pa (I to 5 torr). Optimum uniformity in carburizing is obtained in this range. The gas may be any hydrocarbon. The simplest and most commonly used is CHJ (methane). Propane (C3Hs) is also used. To be successhtl in plasma carburizing, the plasma envelope must surround the parts, meaning that parts must be finned. or positioned so that they do not touch each other (see Figure). In the figure universal joint components are stacked in layers separated by a woven wire screen between layers.
Applications The range of applications
includes
1020, 1521, and 8620 steels.
Reference I. ASM Metals Handbook, tional, 1991. p 353
Heat Treating,
Vol 4. 10th ed., ASM
Intema-
58 / Heat Treater’s
Guide
Carbonitriding This is a modified form ofgas carburizing. rather than a form of nitriding. The modification: ammonia is combined with the gas carburizing atmosphere to add nitrogen to the carbutized case as it is being produced. Nascent nitrogen is at the work surfaces. Ammonia dissociates in the furnace atmosphere: nitrogen diffuses into the steel simultaneously with carbon. Ref I.
Characteristics Carbonitriding is similar to liquid cyaniding in terms of its effects on steel. The process is often substituted for liquid cyaniding because of problems in the disposal of cyanide-bearing water. Case characteristics of carburized and nitrided parts are also different; carburized cases normally
Effect of Material/Variables Formation in Carbonitrided
hlaterial/processing
variables(a)
Tempenture increase Longer cycles Highercase nitrogen levels Higher case carbon levels Alumintu~-killed steel tncrcased alloy content of steel Severe prior cold working of material Ammonia addition during heat-up cycle
on the Possibility Cases
of Void
do not contain nitrogen, and nitrided cases are primarily nitrogen, while carbonitrided cases contain both carbon and nitrogen. Ability to produce hard, wear-resistant cases, which are generally in the range of 0.075 to 0.75 mm (0.003 to 0.030 in.), is the typical reason for selecting this process. Cases have better hardenability than carburized types (nitrogen increases the hardenability of steel); nitrogen is also an austenite stabilizer. and high nitrogen levels can result in retained austenite. particularly in alloy steels. Economies can be realized with carbonitriding and quenching in the production of hard cases within a specific case depth range and for either carbon or low-alloy steel. With oil quenching, full hardness with less distortion can be obtained, or in some cases, with gas quenching, using a protective atmosphere as the quenching medium. Another plus: carburizing and carbonitriding often are combined to get deeper case depths and better performance in service than are possible with carbonitriding alone.
Operating Possibility of void formation Increased Increased Increased increased Increased DeWXsed Increased Increased
Information
Industrial practice for time and temperature is indicated in an adjoining Figure. which shows the effects of time and temperature on effective depth (as opposed to total case depth). Effects of total furnace time on the case depth of 1020 steel is shown in adjoining Figure (a). Specimens were heated to 705.760,815. and 870 “C
Results of a survey of industrial practice regarding effects of time and temperature on effective case depth of carbonitrided cases
(a) All other variables heldconstant
Effects of temperature and of duration of carbonitriding on effective case depth. Both sets of data were obtained in the same plant. Note that upper graph (for 1020 steel) is in terms of total furnace time, whereas bottom graph (for 1112 steel) is for 15 min at temperature.
End-quench hardenability curve for 1020 steel carbonitrided at 900 “C (1650 OF) compared with curve for the same steel carburized at 925 “C (1700 “F). Hardness was measured along the surface of the as-quenched hardenability specimen. Ammonia and methane contents of the inlet carbonitriding atmosphere were 5%; balance, carrier gas.
Guidelines
Typical
Applications
and Production
Cycles
for the Heat Treatment
of Steel / 59
For Carbonitriding
Part
Steel
Case depth mm 0.001 in.
Furnace temperature T OF
Carhoo steels Adjusting yoke, 25 hy 9.5 mm ( I by 0.37 in. j Bearing block,64 by 32 by 3.2 mm (2.5 by I.3 by 0.13 in.) Cam. 2.3 by 57 by 64 mm (0. I bj 2.25 hy 2.5 in.) cup. I3 g (0.4602) Distributordriveshaft. I25 mmOD by 127 mm (5 by 5 in.) Gear,-U.Smmdiamby3.2mm(l.75by0.l2Sio.) Hex nut. 60.3 hy 9.5 mm (2.4 b] 0.37 in.) Hood-latch bracket, 6.1 mm diam (0.25 in.) Link 2 hy 38 by 38 mm (0.079 hy I .S b> I.5 in.) hlandrel, 40 g ( I .AI 02) Paper-cutting tool, 4 IO mm long Segment 2.3 hy 44.5 hy 44.5 mm (0.09 by I.75 by I .7S tn.) Shaft. 1.7 mm diam hy IS9 mm (0. I9 bj 6.25 in.) shiftcollar,s9g(2.loz) Slidingspurgear,66.7mmOD(2.625 in.) Spring pin, 14.3 mmOD by I l4mm(O.S6 by-l.5 in.j Spur pinion shaft. II .3 mm OD (I ,625 in.) Transmission shift fork. I27 hy 76 mm (5 by 3 in.)
1020 1010 1010 101s 1015 1213(h) 1030 1015 1022 III7 1117 1010 1213(b, III8 1018 1030 1018 1040
0.05-O. IS 0.05-O. I5 0.38-0.45 0.08-o. I3 0. IS-O.25 0.30-0.38 0. IS-O.25 0.05-0.1.5 0.30-0.38 0.20-0.30 -0.7s 0.28-0.45 0.30-0.38 0.30-0.36 0.38-0.50 0 25-0.50 0.38-0.50 0.25-0.50
2-6 2-b IS-18 3-s 6-10 12-15 6-10 2-6 11-15 8-l’ -30 15-18 12-15 12-l-l 15-20 IO-20 IS-20 I O-20
775 and 715 775 and 7-lj 855 790 8lSand7-15 855 815and745 775 and 745 855 845
1125and 1375 1125 and I375 IS75 I150 I SO0and I375 I575 IS00 and I375 I-I?i and I375 IS15 IS50
855 815 77s 870 815and7-15 870 815and7-15
I S75 I.500 I-130 1600 IS00 and I375 I600 I500 and I375
Alloy steels Helical gear, 82 mm OD (3.23 in.) Input sti I.2 kg (2.6 lb) Pinion gear. 0.2 kg (O.-U lb) Ring gear, 0.9 kg (2 lb) Segment I .4 hy 83 mm (0.OS.Tby 3 17 in.j Spur pinion shaft. 63.5 mm OD by 203 mm (2.S by 8 in.) Stationary gear plate, 0.32 kg (0.7 Ihj Transmission main shaft sleeve, 38 mm OD by 25 mm (I .S by 2 in.) Transmission main shaft washer, 57 mm OD b! 6.4 mm (2.25 b> 0.25 in.)
8617H 5140 4017 1047 8617 5 I40H 5110 8622 8620
0.50-0.7s 0.30-0.3s 0.30-0.3s 0.20-0.30 0. IX-0.2s 0.0.5-0.20 0.30-O 35 0. I s-0.25 0.25-0.50
20-30 12-14 12-11 8-10 7-10 2-8 12-l-l 6-10 IO-20
845 775 77s 760 815 845 775 8I5and715 8lSand715
IS50 I430 l-130 l-m0 1500 1550 I430 I SO0and I375 15OOand 1375
Total time in Furnace
Quench
64min @mitt 2’/?.h ‘/? h 108min I v4 h 64min &min I ‘/? h I ‘/z h
Oil Oil Oil Oil Gas(a) Oil(c) Oil Oil Oil Oil
2h:fj I44min 2 h(lI I62 min
Oil Gas(a)(d) Oil(e) Oil(g) Oil Oil(h) GW)
6h(f)
Oil(g)
51/?h 5 ‘/2 h 9h I 1/Zh I MD 51/, h 108min I62 min
Oil(e) Oil(e) Oil(i) Ga.sW Oil(j) Oil(e) Gt3.W
(a) Modifiedcarboniuidingatmosphere. (b) Leaded. rc) Tempered at 190°C (375 “F). td)Temperedal 150°C (300 “FJ. (c)Tempered ;II 16.5“C (325 “F). (f Tiieat (g)Oilatl50”C(300”F):temperedatlS0”C(300”~forIh.(h)oilatl50”C(,300”F)temper~dat76O”C(500”F)forIh.(i)Temprredatl75”C(350oF).(i)OilatISO”C(300 “F); tempered at 230 “C (150 “F) for 2 h. OD, outside diameter
Effect of ammonia additions on nitrogen content and formation ‘C(1695 “F) 0.13% (c) 950 “C (1720 “F) 0.10% CO,
co,.
of subsurface
Gas(a) temperature,
voids in foils. (a) 850 “C (1580 “F) 0.29% CO,. (b) 925
60 / Heat Treater’s Guide (1300,1400,1500, and 1600 “F). An adjoining Figure(b) shows total case depthsobtained with 1112steelheld at 15 min at temperaturesbetween750 and 900 “C (1380 and 1650 “F). Depth of Case. l
l
l
l
l
Casedepthsof 0.025 to 0.075 mm (0.001 to 0.003 in.) commonly areput on thin parts requiring wear resistanceunder light loads. Casedepthsup to 0.75 mm (0.030 in.) are applied to parts such ascams for resistanceto high compressiveloads. Casedepthsof 0.63 to 0.75 mm (0.025 to 0.030 in.) are applied to shafts and gears subjectedto high tensile or compressive stresses,or contact loads. Medium-carbon steel with hardnessesof 40 to 45 HRC normally require less casedepth than steelswith core hardnessesof 20 HRC or below. Low-alloy steelswith medium-carbon content, i.e., those used in transmission gears for autos, often have minimum case depths of 0.2 mm (0.008 in.).
Hardenability of Case. Case hardenability is significantly greater when nitrogen is addedby carbonitriding than when the samesteel is only carburized (seeFigure). This opensup the use of steelsthat could not have uniform hardnessif they were only carburized and quenched. When core properties are not important, carbon&riding permits the use of low-carbon steelsthat cost less and may provide better machinability or formability. Because of the hardenability effect of nitrogen, the process makes it possible to oil quench such steels as 1010, 1020, and 1113 to obtain martensitic casestructures. Void Formation. Casestructuresmay contain subsurfacevoids or porosity if processing conditions are not adjustedproperly (seeFigure). The problem is related to excessiveammonia additions. Factorsthat contribute to the problem are summarizedin an adjoining Table. Furnaces. Almost any furnace suitable for gas carburizing can be adaptedfor carbonitriding. Atmospheresgenerally are a mixture of carrier gas, enriching gas, and ammonia. Basically, the required atmospherecan be obtained by adding 2 to 12 percent ammonia to a standardgas-carburizing atmosphere. Quenching. Whether parts are quenched in water, oil, or gas depends on allowable distortion, metallurgical requirements,caseor core hardness, and type of furnace used.
Tempering. Many shallow caseparts are used without tempering. Nitrogen in the caseincreasesresistanceto softening-the degreedepending on the amount of nitrogen in the case.
Applications Applications are more restricted than those for carburizing. The process is largely limited to case depths of approximately 0.75 mm (0.03 in.). Typical applications and production cycles for a number of steelsare listed in an adjoining Table. On the plus side, resistanceto softening during tempering is markedly superior to that of a carburized surface. Other benefits include residual stresspatterns,metallurgical structure, fatigue and impact strength at specific hardnesslevels, and the effects of alloy composition on caseand core hardness characteristics. In many applications, properties equivalent to those obtained in carburizing alloy steelscan be obtained with less expensive gradesof steel. On the minus side, a carbonitrided caseusually contains more retained austenite than a carburized caseof the samecarbon content. However, the amount of retained austenite can be significantly reduced by cooling quenchedparts to -40 to -100 “C (-40 to -150 “F). P/M Applications. The processis widely usedin treating ferrous powder parts. Partsmay or may not be copper infiltrated prior to carbonitriding. The processis effective in casehardening compactsmadeof electrolytic powders which are difficult to harden by carburizing. To avoid such problems,parts are treatedat 790 to 8 15 “C (1455 to 1500 “F). Lower rates of diffusion at these temperaturespermit control of casedepth and allow the buildup of adequate carbon in the case. The presence of nitrogen provides sufficient hardenability to allow oil quenching. File hard cases(with microhardness equivalent to 60 HRC) with predominately martensitic structurescan be consistently obtained. Partsusually are temperedeven though there is little danger of cracking untemperedpieces. However, there is a reasonfor tempering: it facilitates tumbling and deburring operations.
Reference 1. ASM Metals Handbook, Heat Treating, Vo14, 10th ed., ASM Intemational, 1991,p 376
Gas Nitriding In this process,nitrogen is introduced into the surface of a solid ferrous alloy at a temperaturebelow AC] in contact with a nitrogen gas, usually ammonia, Ref 1.
Nitriding downgradesthe corrosion resistanceof stainlesssteel because of its chromium content. On the upside, surface hardnessis increasedand resistanceto abrasion is improved.
Characteristics
Operating
A hard case is produced without quenching. Benefits of the process include:
The nitriding temperaturefor all steelsis 495 to 565 “C (925 to 1050OF). All hardenablesteelsmust be hardenedand temperedprior to nitriding. The minimum tempering temperature usually is at least 30 “C (55 “F) above the maximum nitriding temperature. Either a single- or double-stageprocess may be used in nitriding with anhydrous ammonia. The operating temperatureof the single-stageprocessis in the range of about 495 to 525 ‘C (925 to 975 “F). A brittle, nitrogen-rich layer, called the white layer, is produced on the surfaceof the case. Reducing white layer thicknessesis a benefit of the double-stageprocess-also called the Floe process.Nitriding applications for both processes are listed in an adjoining Table. White layers produced in the single- and double-stageprocessesare comparedin an adjoining Figure. Examples of where nitriding eliminates production or service problems with parts case hardenedby other methodsare found in an adjoining Table.
l l l l
High surfacehardness Improved resistanceto wear and galling Improved fatigue life Improved corrosion resistance(stainless steel is an exception)
In addition, distortion and deformation are less than they are in carburizing and other conventional hardening processes.Best results are obtained with steels containing one or more of the nitride-forming alloying elements-aluminum, chromium, vanadium, tungsten, and molybdenum. Other alloying elements such as nickel, copper, silicon, and manganese have little, if any, effect on nitridmg characteristics.Alloys containing 0.85 to 1.50 percent aluminum yield the best results (seeTable).
Information
Guidelines
Hardness gradients and case depth relations for single-stage nitrided aluminum-containing
for the Heat Treatment
SAE 7140 steel
of Steel / 61
62 / Heat Treater’s
Nitriding
Guide
Applications
and Procedures
Part
Dimensions or weight of part
Single-stage nitriding Hydraulic barrel Trigger for pneumatic h-er Governor push button Tachometer shaft Helical timing gear Gear Generator shaft Rotor and pinion for pneumatic drill Sleeve for pneumatic tool clutch hlarine helical transmission gear Oil-pump gear Loom shuttle Double-stage nitriding Ring gear for helicopter main transmission Aircraft cylinder barrel Bushing Cutter spindle Plunger CtXtlkShilft Piston ring Clutch Double helical gear Feed screw Pumper plunger Seal ring Stop pin Thrust collar Wear ring Clamp Die Gib Spindle Torque gear Wedge Pumper plunger
SOmtn(2in.jOD.
19mm(3/~in.jfD.
Steel
ISOmm(6in.jlong
Nitriding
time, h
6mm(‘/Iin.)diam 380mm(l5in.)long 205mm(8in.)OD(-t.Sk or IOlb) 9 Ltin.)thick 50mm(2in.)OD.6mm( 25 mm (I in.) OD. 355 mm (14 in.) long 22 mm (7/8in.)diam 38 mm ( I ‘/J in.) diam 635 mm (3-Sin.) OD (227 kg or 500 lb) SOmm(2in)OD. 180mmt7in.)long I SOmm by 25 mm by 25 mm (6 in. by I in. by I in.)
AMS 6170 A hf.5 6-470 AMS 6-!70 AhlS 6-47s -1140 -II-IO -II-t0 -II-IO 4l-u) -II42 1330 4lOstainless
230
380mm(lSin.)OD.3S0mm(l3.8in.)a),~mm(3.Sin.)long 180mnt(7in.)DD,305mmt,12in.)long lOkg(23Ibj 3 kg(7 lb) 7Smm(3in.jOD.l52Smnt16Oin.)long 205 mm (8 in.) OD (journals). -I m (I3 ft) long lSOmm(6in.)OD.4.2Sm(I-lti)long I kg(2 lb) 50kg(l08lb) 4 kg (9 lb) 0.5 kg t I lb) 9.S kg (2 I Ihj 3 kg (7 lb) 3.6 kg(8 lb) 40kg(87lh) 7kg(l5Ib) 21 kg(A7lbj IO kg(23 Ibj I22 kg(270lb) 62Skg(l38Ib) I8kg(Ilb) I.lkg(3lb)
AhlS 6-170(a) A MS 6470 AhlS 6170 AhlS 6470 AMS 6-t7s -1130 3130 -II40 -II-l0 -11-M) 4l-tO -1130 41-u) 11-M -II40 1150 43u) -t3Jtl 1330 J3-u) -I340 -120stainless
60(b)
2 24 24 9 9 32 25 8
35(c) 90 4s 72 65 65 2 45 I27 90 2 90 2 2 90 42 127
Note: OD,outerdiameter; ID, innerdiameter. (a) Vacuum melted. (h)9 hat 525 “C (975 “F). 5 I hat S-t5 to SSO”C( 1015 to 1025 “F). (c)6 hat S’S “C(975 “Fj, 29hat S65 “C( 1050°F)
Examples of Parts for Which Nitriding Requirements Part
Proved Superior
to Other Case-hardening
Requirement
Gear High-speed pinion (on gear motor) Bushings (for conveyor rollers handling ahrasive alkaline material) Spur gears (in train of power geats; IO-pitch. tip modified)
Good wear surface and fatigue properties Provide teeth with minimum (equivalent) hardness of SOHRC High surface hardness for abrasion resistance; resistance to alkaline corrosion Sustain continuous Hertz stress of 1035 klPa ( I50 ksi) (overload of I MO hlPa, or 275 ksi). continuous Lewis stress of 275 hlPa(40 ksijto\erloadof725 hlPa or IO5 bij(c)
Processes
for Meeting
Material and process originally
used
Carhurized 33 IO steel 0.4 to 0.6 mm (0.017 to 0.02.5 in.) case X620 steel gas carburized at 900 “C ( I650 OF)to 0.5 mm (0.02 in.) case, direct quenched fmnt 815 “C ( 1550 “F), and tempered at 205 “C (300°F) Carburized bushings Carbutired AhlS 6260
Resultant problem Gear
Good wear surface and fatigue properties
High-speed pinion (on gear motor)
Pro\ ide teeth with mintmunt (equivalent) hardness of SOHRC
Difficulty in obtaining satisfactory case to meet a reliability requirement Distortion in teeth and bore caused high rejection rate
Bushings (for comevorrollers site alkaltne material)
handbngahra-
High surface hardness for abrasion resistance; resistance to alkaline corrosion
Sen ice life of bushings was short because of scoring
Spurgears(in trainof powergeats; IO-pitch, tip modified)
Sustain continuous Hertz stress of 1035 hiPa t 150 ksij (overload of IS50 hIPa. or 235 ksi ). continuous Lea is stress of 275 hlPa (-IO hi) (overload of 72s hlPs or IO.5ksij(c)
Gears failed because of inadequate scuffreststartce. also suffered property losses at high operating temperatures
Solution Ah1.86170substituted for33lOand double-stage nitrided for 25 h ll4Osteel. substituted for 8620, was heat treated to 255 HB; parts were rough machined tinish machined. niuided(a) Substitution of Nitralloy I35 type G (resulfurired) heat treated to 269 HB and nitrided(hj Substitution of material of H I I type, hardened and multiple tempered (3 h + 3 h) to 18 to 52 HRC, then doublestage nitrided(d)
(a) Single-stage nitrided at5 IO’C (950°F) for 38 h. Cost increased 55,. but rejection rate dropped to zero. (b) Single-stage ninidedat S 10°C (950°F) for 38 h. Casedepth wasO.-l6 mm (0.018 in.), and hardness was 94 HR IS-N: parts had three times the senice life of carburized parts tc) hlust withstand operating temperatures to 290°C (550 “Fj. (d) IS hat 5 IS “C (%O “F) ( IS to 25% dissociation); then 525 ‘C (980 “F) (80 to 83% dissociation). Effective case depth (IO 60 HRC). 0.29 to O.-l mm (0.010 to 0.015 in.): case hardness, 67 to 72 HRC (converted from Rockwell IS-N scale)
Guidelines The fust stage of the double-stage process is the same as that for the single-stage process, except for time (see Table). The operating tcmperature in the second stage may nc the same as that in the first stage, or it ma! be increased from 550 to 565 “C ( IO20 to IO50 “F). The higher temperature increases case depth. Prior to nitriding. parts should be thoroughly cleaned ttypicall> mrith vapor degreasing) after they are hardened and tempered. Furnace Purging. After loading and sealing the furnace at the start of the nitriding cycle. air must be purged from the retort before the furnace is heated above IS0 ‘C (300 “F). Purging pre\.ents osidation of workpieces and furnace components. When ammonia is the purging atmosphere, pur_ging avotds the production of a potentially explosi\.c mixture. Nitrogen IS the preferred quenching medium. Under no circumstances should ammonia be introduced into a furnace containing air at 330 ‘C (6X “F) because of the explosion hazard. Furnaces should also be purged at the conclusion of the nitriding cycle. during the cool-down period. At this time. it is common practice to remobe an) ammonia in the retort with nitrogen. Emergency Purging. If the ammonia suppI is cut off during the nitriding cycle or a suppI! line hreaks. air can be sucked into the fumncethe greatest danger is dunng the cooling cycle. The common safety measure is an emergency purging system that pumps dry rutrogen or an oxygenfree. generated gas and maintains a safe pressure. Case Depth Control. Case depth and case hardness VW \\r;th the duration of the nitriding cycle and other process conditions. Hardness
Nominal Composition Gas Nitrided
SAE
7140
Steel AMS
6470 6475
Nitralloy
and Preliminary
C
hln
Si
G 135hI
0.35 0.42
0.55 0.55
N EZ
0.2-l 0.35
0.55 0.80
0.30 0.30 0.30 0.30
(a) Sections up IO SO mm (2. in.) in diameter.
Microstructure
Heat-Treating
3.5
of Steel / 63
gradients and case depths obtained in treating SAE 7l-lO (AhlS 6470) as a function of cycle time and nitriding conditions are indicated in an adjoining Figure. Equipment. Several designs are in common use, including the vertical retort furnace (see Figure). bell bpe movable furnace, box furnace. and tuhe retorts. hlost furnaces ‘are of the batch type. Furnace fixtures are similar in design to those used in gas carburizing. Ammonia and dissociated products can react chemically with material in retorts. fans. work baskets. and fixtures. Alloys containing a high percentage of nickel and chromium normally are used in furnace parts and fixtures (see Table). Ammonia Supply. Anhjdrous liquid ammonia (refrigerator grade. 99.98 percent NH? hy lbeight) is used.
Applications The list of applications l l
l
l
l
includes:
Aluminum containing. low-alloy steels (see Table) Medium-carbon. chromium-containing, low-alloy steels of the 4100. -l300. 5 100.6 100, 8600. 8700. and 9800 series Hot-work die steels containing 5 percent chromium. such as HI I. HI?. and HI? Lo)<-carbon. chromium-containing. low-alloy steels of the 3300. 8600. and 9300 series Air-hardening tool steels. such as A-2. A-6. D-2. D-3. and S-7
Cycles for Aluminum-Containing
Composition, W Cr Ni 1.2 1.6 1.15 I.15
for the Heat Treatment
hln
Al
0 20 0 38 O.?i 0.X
I .o I.0 I .o I .o
se
.:. 0.i)
Low-Alloy
Steels Commonly
Austenitizing temperature(a) T OF 955 95s 900 9SS
I750 I7SO 1650 1750
Tempering temperature(a) T OF 56570s
10.50-1300
56.5-70s 650-675 565-705
1050-1300 I X0- I250 IOSO-1300
quenched in oil: larger sections ma! bc mater quenched
of quenched and tempered 4140 steel after (a) gas nitriding for 24 h at 525 “C (975 “F) with 20 to 30% dissociation and (b) gas nitriding for 5 h at 525 “C (975 “F) with 20 to 30% dissociation followed by a second stage of 20 h at 565 “C (1050 “F) with 75 to 80% dissociation. Both specimens were oil quenched from 845 “C (1550 “F), tempered for 2 h at 620 “C (1150 “F), and surface activated with manganese phosphate before nitriding. (a) Structure after single-stage nitriding 0.005 to 0.0075 mm (0.0002 to 0.0003 in.) white surface layer (Fe,N), iron nitride, and tempered martensite. (b) The high second-stage dissociation caused absence of white layer, and the final structure had a diffused nitride layer on a matrix of tempered martensite. Both 2% nital, 400x
64 / Heat Treater’s
Guide
Recommended Materials Nitriding Furnaces
for Parts and Fixtures
Materials are recommended on the basis of maximum temperature of 565 “C (1050 “F).
in operating
Vertical retort nitriding furnace. 1, gasket; 2, oil seal; 3, work basket; 4, heating elements; 5, circulating fan; 6, thermocouple; and 7, cooling assembly. At end of cycle, a valve is opened and fan (not shown) incorporated in the external cooler circulates atmosphere through the water-jacketed cooling manifold.
Material Wnwght
Part Retorts(a) FarIS Tmys. baskets. fixtures Thermocouple protection tube
l)ye 330; tnconel600 lype 330; lnconel6oo Types 310.330; tnconel600 l)pe 330; Inconel600
cast Not usually cast 3S- IS orequivalenl 3S- 1.Sorequivalent Not usually cast
(a) Periodic inspection of austenitic stainless steel retorts is mandatory because ofembrittlement after long exposures to nitriding. Retorts of 18-8 stainless steel lined nith high-temperature glass habe been used successfully.
l l l l l
High-speed steels, such as M-2 and M-4 Nitronic stainless steels, such as 30.40,50. and 60 Ferritic and martensitic stainless steels of the 400 and SO0 series Austenitic stainless steels in the 200 and 300 series PH stainless steels, such as 13-8 PH. 15-5 PH. 17-7 PH. A-286, AM 350, and AM 355
As stated previously, gas nitriding reduces the corrosion resistance of stainless steels. However, all of these steels can be nitrided to some degree. Prior to nitriding. some surface preparations unique to stainless steel are necessary. Primarily, the chromium oxide film that provides corrosion protection must be removed by such processes as dry honing, wet blasting, and pickling. The treatment must precede placing workpieces into the furnace. In addition, all parts must be perfectly clean and free of embedded foreign particles. Special nitriding processes include pressure nitriding, bright nitriding, pack nitriding, ion (plasma) nitriding, and vacuum nitrocarburizing.
Liquid
Reference I. ASM Metals Handbook, Heat Treating, Vol 4. 10th ed.. ASM tional. 1991, p 387
Intema-
Nitriding
Processing takes place in a molten salt bath at the gas nitriding operating temperature-5 IO to 580 “C (950 to 1075 “F). The case hardening medium is a molten, nitrogen-bearing, fused-salt bath containing either cyanides or cyanates. Ref I.
salts. Cyanide-free salt compositions are available. They have gained wide acceptance within the heat-treating industry because they contribute substantially to the alleviation of a potential source of pollution.
Characteristics Bath compositions are similar to those in liquid carburizing and cyaniding. However, liquid cyaniding has an operating temperature lower than the critical transformation temperature. This means it is possible to treat finished parts because dimensional stability can be maintained in liquid carburizing. The process also improves surface hear resistance and the endurance limit in fatigue. Also, the corrosion resistance of many steels is improved. Generally, the process is not suitable where applications require deep cases and hardened cores. Gas nitriding and liquid nitriding have common applications. Gas nitriding may have the edge where heavier case depths and dependable stopoffs are specified. Four examples of conversions from other processes to liquid nitriding are summarized in an adjoining Table. The process has become the generic term for a number of different fusedsalt bath processes, all of which are carried out at the subcritical transformation temperature. The basic processes are identified in an adjoining Table. A typical commercial bath is a mixture of sodium and potassium
Results of liquid pressure nitriding on type 410 stainless steel $c;xxition.
O.l2C-0.45Mn-0.41
Ni-11.900;
core hardness,
24
Guidelines
Automotive Parts for Which Liquid Service Requirements Component
Nitriding
Requirement
Proved Superior Materialand pmcess originally
to Other Case-Hardening
used
Processes
Wthstand thrust load without galling and deformation
Bronze, carbonitrided
shafl
Resist wear on splines and bearing area
Induction
Seat bracket
Resist wear on surface
1020 steel, cyanide treated
Distortion; high loss in straightening(b)
Rocker arm shaft
Resist water on surface; maintain w-try
SAE 1045 steel, rough ground, induction hardened straightened, finish ground, phosphate coated
Costly operations
1010 steel
Bronze galled, deformed; Warped
harden through areas
Required costly inspection
increase incost. (b)Also.
Nitrogen gradients in 1015 steal as a function of time of nitriding at 565 “C (1050 “F), using the aerated bath process
steel
brittleness.
and material
(c) Resulted in lessdistortionand
of Steel / 65
for Meeting
Solution
Resultant problem
Thrust washer
(a)Resultedin improved product performanceandextended life, withno loss.(d) Eliminated finish grinding. phosphatizing. and straightening
for the Heat Treatment
101Osteelnitrided9Ominin cyanide-cyanate bath at 570 “C ( 1060 OF) and water quenched(a) Nitride for 90 min in cyanidecyanate salt bath at 570 “C ( 1060 “F) 1020 nitrided 90 min in cyanidecyanate salt bath and water quenched(c) SAE I01 0 steel liquid-nibided 90 min in low-cyanide fused salt at 570to580”C( 106Oto 1075 “F)(d) briflleness.andeliminationofsc7ap
Depth of case for several chromium-containing low-alloy steels, aluminum-containing steels, and tool steels after liquid nitriding in a conventional salt bath at 525 “C (975 “F) for upto70h
Nitrided case and diffusion zone produced by cyanide-cyanate liquid nitriding. The characteristic needle structure is seen only after a 300 “C (570 “F) aging treatment.
Liquid nittiding processes include liquid pressure nitriding. aerated bath nitriding, and aerated, low-cyanide nitriding. Results in liquid pressure nitriding type 410 stainless steel are found in an adjoining Figure. Results in aerated salt bath nittiding a 1015 steel part are shown in an adjoining Figure. A nitrided case and diffusion zone obtained in cyanide-cyanate liquid nittiding are shown in an adjoining Figure.
Operating Important l l
Information procedures
include:
Initial preparation and heating of the salt bath Aging of molten salts, when required
66 / Heat Treater’s
l
Analysis
Guide
and maintenance
of baths
practically all steels must be quenched and tempered for core properties before nitrided or stress relieved for distortion. Prior heat treatment requirements are similar to those for gas nitriding. Parts are hardened prior to nitriding. Tempering temperatures should be no lower than the nitriding temperature, and preferably, slightly higher.
Liquid
Nitriding
Starting Baths. Baths basically are sodium and potassium cyanides, or sodium and potassium cyanates. Cyanide, the active ingredient, is oxidized to cyanate by aging. The commercial salt mixture of 60 to 70 percent sodium salts and 30 to 40 percent potassium salts is melted at 540 to 595 “C (1000 to I IO5 OF). During melting, a cover should be placed over the retort to guard against spattering or explosion of the salt, unless
Processes
Suggested Process ideotilication Aerated cyanidecyanate Casing salf Pressure nitriding Regenerated cyanate-carInmate
Operating range composition Sodium cyanide (NaCN), pokssium cyanide (KCN) and potassium cyanate (KCNO). sodium cyanate (NaCNO) Potassium cyanide (KCN) or sodium cyanide (NaCN). sodium cyanate (NaCNO) or potassium sqana~e (KCNO). or mixtures Sodium cyanide (NaCN). sodium cyanate (NsCNO) potassium m A: Potassium cyanate (KCNO). carbonate (K,CO,) l)pc B: Potassium cyanate (KCNO), potassium carbonale(K2C0,). I-10ppm,sulFur(S)
Chemical nature
post treatment
Operating temperature T OF
U.S. patent number
Strongly reducing
Water or oil quench; nitrogen cool
570
1060
Strongly reducing
Water or oil quench
s I O-650
95O- I200
Strongly reducing Mildly oxidizing
Aircool Water, oil. or salt quench
525.565 580
975-1050 1075
4.019.928
Mildly oxidizing
Water. oil quench, or salt quench
S-IO-575
Iwo-1070
4006,643
3.208.885
Hardness gradients for several alloy and tool steels nitrided in salt by the liquid pressure process. Rockwell C hardness values are zonvetted from Knoop hardness measurements made using a 500 g load. Temperatures are nitriding temperatures.
Guidelines
for the Heat Treatment
of Steel / 67
equipment is completely hooded and vented. Salts must be dry before placing them in the retort; entrapped moisture can cause eruption when the salt is heated. Baths are heated internally or externally. Bath Maintenance. All work placed in the bath should be thoroughly cleaned and free of surface oxide. Either acid pickling or abrasive cleaning prior to nitriding is recommended. Finished parts should be preheated prior to immersion in the bath to rid them of surface moisture. Safety. Compounds containing sodium cyanide or potassium cyanide or both can be handled safely with the proper equipment and must be neutralized by chemical means before discharge. These compounds are highly toxic. Great care should be taken to avoid taking them internally. or aUowing them to be absorbed through skin abrasions. Another hazard is caused by contact between the compounds and mineral acids. Hydrogen cyanide gas, an extremely toxic producl, is produced. Exposure can be fatal. Equipment. Salt bath furnaces may be heated by gas. oil, or electricity. and essentially are similar in design to furnaces used in other processes. Batch furnaces are the most common, but continuous operations are feasible.
up to 70 h. Effective cyanide content of the bath was 30 to 35 percent and cyanate content was IS to 20 percent. Before being nitrided. all parts were tempered to the core hardnesses indicated in the Figure previously cited. Steels treated included three chromium-containing, low-alloy steels (4140, 3310, and 6 150); tuo aluminum-containing nitriding steels (SAE 7 I40 and 6475); and four tool steels (HI I, H 12. h450, and D2). An adjoining Figure presents data on core hardnesses obtained in liquid pressure nitriding several alloy and tool steels: SAE 7140. AMS 6475, 4l-tO. 4310; and medium carbon HI I, HIS, and MSO. In this instance, case depths and hardnesses are comparable to those obtained in single-stage gas nitriding. In treating high-speed steel cutting tools with liquid nitriding, cases have a lower nitrogen content and are more ductile than those produced in gas nitriding.
Applications
I. .LWt Mcvals Handbook, tional. 1991, p-110
Reference Hem Trrmting,
Vol 4, 10th ed., ASM Intema-
Data in an adjoining Figure show depth of case obtained in a number of steels treated in a conventional liquid nitriding bath at S2S “C (975 ‘F) for
Plasma
(Ion)
Nitriding
In this vacuum process, nascent (elemental) nitrogen is introduced to the surfaces of workpieces for subsequent diffusion into the metal. High voltage electrical energy forms a plasma through which nitrogen atoms are accelerated to impinge on workpieces. Ion bombardment heats workpieces, cleans surfaces, and provides active nitrogen (Ref I).
Compound layer of y’ (Fe,N) on the ion-nitrided surface of quenched and tempered 4140 steel. The y ’ compound layer is supported by a diffused case, which is not observable crograph. Nital etched. 500x
in this mi-
Characteristics The process, in comparison with conventional gas nitriding. provides more precise control of nitrogen supply at the workpiece surface. Another advantage: ability to select either an epsilon (E) or gamma (y) monophase layer, or prevent white layer formation entirely. A compound layer on quenched and tempered -II30 is shown in an adjoining Figure. The diffusion zone in type 416 stainless steel is shown in another Figure A third Figure shows typical gas compositions and resulting metallurgical configu-
Observable diffusion zone on the unetched (white) portion of an ion-nitrided 416 stainless steel. Nital etched. 500x
68 / Heat Treater’s
Guide
rations. The process is replacing carbonitriding for better dimensional control and the reduction or elimination of machining after heat treating.
Operating
Information
A typical ion nitriding vessel is depicted in an adjoining Figure. Operating temperatures are in the range of 375 to 650 ‘C (705 to 1200 “F). At the lower temperacure, the amount of residual stress relief is minimized. Because loads are gas cooled. they do not experience distortion from temperature gradients or from martensitic formation. After work is heated to the desired temperature, process gas is admitted at a flow rate determined by the load surface area. Pressure is regulated in the I to IO torr range by a control valve just upstre‘am from the vacuum pump. Process gas is normally a mixture of nitrogen. hydrogen, and occasionally, small amounts of methane. Cooling is by backfilling with nitrogen or other inert gases, and by recirculating the gas from the load to a cold surface, such as a cold wall. Prior microst.rucNre can influence response to nitriding. For alloy steels, a quenched and tempered strucNre is believed to get optimum results. Tempering temperatures should be IS to 25 “C (25 to 45 “F) higher than the anticipated nitriding temperature to minimize further tempering of the core during the nitriding process. Hardness profiles for typical ion nitrided alloys are shown in an adjoining Figure.
Applications Response to ion nitriding depends heavily on the presence of strong. nitride-forming elements. Plain carbon steels can be treated. but cases aren’t significantly harder than the cores. Steels in the Nitralloy series with about I percent aluminum and I to I.5 percent chromium are the premier applications. Other suitable applications include: l
Chromium-bearing
alloys,
ie., 4 100, 4300, 5 100, 6100, 8600, X700,
9300, and 9800 series l l l
Most tool and die steels, stainless steels, and PH alloys P/M parts (due to porosity, cleaning is a critical requirement) Cast iron wear parts
Typical ion-nitriding
vessel
Gears, crankshafts, applications.
cylinder
liners. and pistons are regarded as excellent
Reference I. ASM Merals Handbook, Hear Treating, Vol 4. 10th ed., ASM tional, 1991, p 120
lntema-
Hardness profile for various ion-nitrided materials. 1, gray cast iron; 2, ductile cast iron; 3, AISI 1040; 4, carburizing steel; 5, low-alloy steel; 6, nitriding steel; 7,5% Cr hot-work steel; 8, coldworked die steel; 9, ferritic stainless steel; 10, AISI 420 stainless steel; 11, 18-8 stainless steel
Guidelines
Typical gas compositions
Gaseous
and the resulting metallurgical
and Plasma
configurations
(Both Processes)
Improving resistance to scuffing is a common benefit of the compound layer produced with these processes. In addition, fatigue properties are
Plasma nitrocarburizing
installation
of Steel / 69
steel
Nitrocarburizing
In the gaseous process, carbon and nitrogen are introduced into a steel, producing a thin layer of iron carbonitride and nitrides. This is the white layer. or compound layer, with an underlying diffusion zone containing dissolved nitrogen and iron or alloy nitrides. Gas processes include Nitemper, Alnat-N, black nitrocarburizing, and austenitic nitrocarhurizing. White layers formed in gaseous nitrocarburizing are shown in an adjoining Figure. Plasma nitrocarburizing is a variant ofglow discharge plasma nitriding (see the article “Plasma (Ion) Nitriding” in this chapter). The microsttucmre produced in ENlOB steel is shown in an adjoining Figure.
Characteristics
of ion-nitrided
for the Heat Treatment
enhanced when nitrogen is retained beneath the compound layer.
Gaseous
in solid solution
in the diffusion
zone
Processes
Operating Information. Parts usually are treated at a temperature of 570 “C (1060 “F), which is just below the austenitic range for the Fe-N system. Treatment times usually run I to 3 h. To get optimum results, surfaces must be free of contaminants, such as oxides, scale, oil, and decarburization. Vapor degreasing is adequate in most applications. Preliminary heat treatments include simple stress relieving and tempering to increase core strength. Both stress relief and tempering should be at temperatures at least 25 “C (45 “F) above the nitrocarburizing temperature to prevent changes in core properties during nitrocarburizing.
for heat treating a load of 3000 automotive seat rails. Source:
Klockner
IONON GmbH
70 / Heat Treater’s
Microstructure
Guide
(a) of a plasma nitrocarburized
EN40B steel sample with (b) the corresponding
Stnztural charactefistics of an austenitic nitrocarburized material. (a) Micrograph of EN32 steel nitmcarburized for 1 h at 700 “C (1290 “F) in ammonia/endothermic gas with 15% residual ammonia and oil quenched. (b) Carbon and nitrogen profiles for EN32 nitrocarbutized for 1 h at 700 “C (1290 “F) in ammonia/endothermic gas with 15% residual NH,
Production Austenitic treatment
x-ray diffraction pattern.
Applications
qitroearburizing type
of Austenitic
Nitrocarburizing Applications
Alpha Plus(0.125mm, or 0.005in., Clutch plates,levers, gears,bushes,thin underlyingcase) pressings Alpha Plus(0.25mm, or 0.010in., Gears,levers,pulleys, liners underlyingcase) Beta (0.60mm, or 0.025in., under- Machine slideways,guide bars,gears, lying case) sprockets,pins, bushes,water-pumpparts, liners,jigs/fixtures, bearings
Microstructure of a plasma nitrocarburized P/M steel (SINTD35) with a compound layer thickness of 10 pm. Source: Klockner IONON GmbH
1
Guidelines
Compound layers formed on iron by gaseous nitrocarburizing at 80x (a, C, d, e, and fetched
in alcoholic
ferric chloride
Fluidized
in various methanol ammonia ratios. Quenched
and hydrochloric
Batch furnaces with integral oil quenches are ideally suited for the process. The hot chamber temperature should be controllable to within k5 “C ( f9 “F) at 570 “C (1060 “F). For safety reasons gas leaks in the furnace and around doors must be minimized. Nitemper Process. Sealed quench furnaces normally are used. Atmospheres consist of 50 percent ammonia and 50 percent endogas. Treatment temperature is 570 “C (1060 “F). Treatment times usually run between I and 3 h. Parts are oil quenched, or cooled under recirculated protective gas. Alnat-N Process. Nitrous oxide in the atmosphere enhances the rate of compound layer formation through the indirect presence of oxygen. Another feature is claimed for this patented process: it is possible to eliminate the addition of a carburizing gas to the basic ammonia/nitrous oxide/nitrogen mixture. Carbon is incorporated into the compound layer by diffusion from the matrix material. Black Nitrocarburizing. This process was fist used as a cosmetic treatment for gaseous nitrocarburized parts for the hydraulic industry. It has since been found that the application of the process can be extended to improving the fatigue, wear, and corrosion properties of mild steels. Austenitic Nitrocarburizing. In this process, the treatment temperature makes it possible to get partial transformation of the matrix to austenite via enrichment with nitrogen. The reason for this is to get around the main disadvantage of ferritic nitrocarburizing: in treating plain carbon steel there
for the Heat Treatment
acid with iodine;
b, etched
samples, in nital with ferric chloride)
of Steel / 71
all shown
is no significantly hardened case below the compound layer. This means resistance of a part to horizontal (contact) stresses is restricted. In the process, the subsurface (but not the entire cross section) is transformed to iron-carbon-nitrogen austenite, which is subsequently transformed to tempered martensite and bainite, with a hardness in the range of 750 to 900 HV (see adjoining Figure and Tablej.
Plasma Process Operating Information. Atmospheres in this instance are mixtures of hydrogen, nitrogen. and carbon-bearing gas. Treatment temperature is 570 “C ( 1060 “F). The compound layer measures >5 pm; surface hardness runs around 350 HV. Parts are cooled under controlled vacuum conditions. Applications. The plasma equipment shown in an adjoining Figure has been treating seat slider rails for autos for a number of years without significant technical or metallurgical problems. Applications include lowalloy, chromium-bearing steels. some plain carbon steels, and, recently, sintered P/M parts, replacing the salt bath process (see adjoining Figure). Reference I. ASM hlnols Handbook. tional. 199l.pd25
Hem Trmtitlg,
Vol 4. 10th ed., ASM Intema-
Bed Hardening
Steel parts are nitrocarburized, carburized, and carbonitrided in fluid bed hmaces. The process also is used in quenching (see article in this chapter). In heat-treating applications, a bed of dry, finely divided (80 mesh to I80 pm) particles, typically aluminum oxide, is made to behave like a liquid bj a moving gas fed upward through a diffuser or distributor into the bed of the furnace.
Characteristics Fluidized beds, using atmospheres made up of ammonia. natural gas, nitrogen, and air or similar combinations, are capable of doing low-temperature nitrocarburizing. Results are equivalent to those with conventional salt bath processes or other atmosphere processes. High-speed steel tools
72 / Heat Treater’s
Fluidized-bed
Guide
furnace
with external
heating
by electrical
resistance
oxynitrided in a fluidized bed have properties similar to those of tools treated by the more conventional gas processes. In carburizing and carbonitriding, results can be similar to those obtained with conventional ammosphere processes. In an adjoining Figure, results in treating SAE 8620 steel are compared with those obtained in gas carburizing. An effective case depth of I mm (0.04 in.) was obtained in I .5 h. Advantages of the process include: l l l l
Carbtizing is rapid because treatment temperatures are high Temperature uniformity is ensured Furnaces are tight; upward pressure of gases minimizes leakage of air Part finishes are uniform
Operating
Information
The carbon potential of the atmosphere varies with the air-to-gas ratio. For each hydrocarbon gas (typically propane, methane, or vaporized methanol) a relationship can be established. Furnaces are equipped with ports and probes to facilitate necessary measurements. Dense phase furnaces are the most widely used in heat treating. In this instance. parts are submerged in a bed of fme. solid particles held in suspension, without any particle entrainment, by a flow of gas. Several methods of heating are available, including external-resistance-heated beds (see Figure); external-combustion-heated beds, submerged-combustion
elements
Comparison of hardness profiles obtained by fluidized-bed and conventional gas carburizing. SAE 8620 steel, rehardened
from 820 “C (1510 “F)
Guidelines
Fluidized-bed
applications;
beds, intemalcombustion, tion. gas-fired beds.
Operational
gas-fired
decision
beds; and two-stage,
into the majority
of Steel
/ 73
model
intemal-combus-
Safety. As with all forms of gas heating, accepted safety
devices are incorporated
for the Heat Treatment
of today’s
furnaces.
Applications Applications of fluidized beds and those of competing processes are listed in an adjoining Figure. Note that the information includes operating temperatures.
Reference I. ASM M~mls Hmcfhok. tional. I99 I, p 43-I
Hmt Trraring. Vol 1. 10th ed., ASM lntema-
74 / Heat Treater’s
Boriding
Guide
(Boronizing)
Process
This is a thermomechanical surface hardening process which is applied to a number of ferrous materials. During boriding, the diffusion and subsequent absorption of boron atoms into the metallic lattice on the surface of workpieces form initial boron compounds, Ref I.
Characteristics The process has advantages over conventional case hardened parts. One is extremely high hardness (between 1450 and 5000 HV) with high melting points of constituent phases (see Table). Typical surface hardness values are compared with those of other treatments in an adjoining Table. In addition, a combination of high surface hardness and low surface coefftcients of the borided layer helps in combating several types of wear, i.e., adhesion, tribe-oxidation, abrasion, and surface fatigue. On the negative side, boriding techniques lack flexibility and are labor intensive, making the process less cost effective than other thermomechanical treatments, such as gas carburizing and plasma &riding. Alternative processes include gas boriding. plasma boriding. fluidized bed boriding. and multicomponent boriding. A diagram of a lluidized bed for boriding is shown in an adjoining Figure.
Typical Surface Hardness of Borided Steels Compared with Other Treatments and Hard Materials MiCl.Ob~dlless,
Material
Multicomponent
Boriding
1600 1800 1900 900 S-IO-600 630-700 900-910 6SO-1700 650-950 looo-1200 ll60-1820(30kg) 1483 (30 kg) I738 (30 kg) lS69(30kg) 2ooo 3500 4ooo 5ooo >I0000
Information
Welt-cleaned material is heated in the range of 700 to 1000 “C (I290 to 1830 “F) for I to I2 h in contact with a boronaceous solid powder, paste, liquid, or gaseous medium. In the multicomponent process, conventional boronking is followed by applying one or more metallic elements, such as ahuninum, silicon, chro-
Melting Point and Microhardness Phases Formed During Boriding Materials
Substrate Fe co
co-‘7.5 Cr
Ni
k&mm~orEV
Boride mild steel Bonded AtSI H I3 die steel Borided AtSl A2 steel Quenched steel Hardened and tempered H I3 die steel Hardened and tempered A2 die steel High-speed steel BM42 Niuicted steels Carburized low-alloy steels Hard chromium plating Cemented carbides, WC t Co AI,O, + ZrO: ceramic Alz03 t TC t ZrO, cemmic Sialon ceramic TIN -liC SIC B,C Diamond
Constituent Phases in tbe boride layer FeB Fe?B COB CozB Co3B COB CozB Co,B(‘?) Ni&3 Ni:B Ni3B
ho lccl MO
Ta
MozB MOB> Mo:Bs WzBs IiB TIBZ TiB TIB: NbB: NbB.l Ta:B
Hf zr Re
TaB: HI-& ZrB: ReB
w Ii Ti-6AI-4V Nb
of Different Boride of Different Substrate
MiCl.0hanlnCS.S
of layer, EV or kg/mm*
Melting point OF OC
1900-2100 1800-2000 I850 1500-1600 700-800 2200 (lOOg)(a) -l55O(lOOg)(a) 700-800 1600 IS00 900 1700~3-00g)(b) 1660 2330 2400-2700 2600 2500 3370
1390
2535
... . .
. ... . . .
2txxl -2100 2100 2300 -1900 2980 .
“’ 3630 -3810 3810 4170 3450 5395
3OOO(lOOgj(a) 2200
3050
5520 “’
2500 2900 2250 2700-2900
32003500 3200 3250 3040 2100
57906330 5790 5880 5500 3810
(a) IOOg load. (bj 2oOg load
Treatments
Multicomponeot boridhrg technique
Media type
61 62
Boroaluminizing Boroaluminizing
Electrolytic salt bath Pack
2
Borochromizing
Pack
2
Borosiliconizing
Pack
2
Borovanadizing
Pack
Reference
Operating
Media composition(s), wt k
Process steps investigated(a)
Substrate(s) treated
S S B-AI AI-B S B-Cr Cr-B B-Si Si-B B-V
Plain carbon steels Plain carbon steels
900( 1650) lOSO( 1920)
Plain carbon steels
Borided at 900 ( 1650) Chromized at loo0 (1830)
3-20% AlzOr in borax 8% B,C t 16% borax 974 ferroaluminum t 3%, NHJZI 5% B.&Z+ 5% KBF, t 905, Sic (Ekabor ffj 78%. ferrochrome + 20% AI?03 + 2C WC1 SB B,C t I% KBF, + 90%. SIC (Ekabor Oj IOOB Si 5% BJ t 5% KBR + 90% Sic (Ekabor U) 60%, ferrovanadium + 37% Al:01 + 3%, NH,CI
(a) S. simultaneous boriding and metallizing: B-Si. borided and then siliconized; Al-B. aluminized and then bonded
0.44 Steel I .O%-C steel
Ikmperature,
OC (OF)
900-lOOO(l650-1830) Borided at 900 ( 1650) Vanadized at 1000 ( 1830)
Guidelines Proven Applications AIS1
for Borided
Substrate material HSI
I020 10-n 1138 1042
E C2 HII HI3
Ferrous
BHI I ...
HI0
I15CrV3 4OCrMnMo7 X38CrMoV5 I X4OCrMoVS I X32CrMoV33
D2
.
s”li
-BSI
D2 L4i
BS224
02
-802
XlSSCrVMol21
Xl6SCrVMol2 56NiCrMoV7
X$k4SrY4
Materials
Diagram
of a fluidized
for the Heat Treatment
of Steel / 75
bed for boriding
Application Bushes, bolts. nozzles. conveyer tubes. base plates, runners, blades, th&d guides Gear drives, pump shafts Pins, guide nngs. gnndmg disks. bolts Casting inserts, nozzles. handles Shaft protection sleeves, mandrels Swirl elements, nozzles (for oil burners). rollen. t&s. gale plates Gate plates Clamping chucks, guide bars Bushes, press tools, plates. mandrels, punches, dies Drawing dies, eje,cton: guides, insen pins Gate platqs,,ben,dmg*es ~h~i~Z%~~~~$ZZlrL~wer dies and matrices for hot forming, disks injection molding dies, fillers. upper and lower dies and matrices for hot forming Threaded rollers, shaping and pressing rollers. pressing dies and matrices Engraving rollers Straightening mllerj Press and drawing matrices. mandrels. liners, dies, necking rings Drawing dies. rollers for cold mills Extrusion dies. holts. casting inserts, $%;$$;;~~~~d en&ving
dies
rollers. bushes, drawing dies,
Microstructure of the case of a borochromtitanized tion alloy steel
construc-
Es2100
4140 4150 4317
708A42 (EnlW -708A42 (CDS-15) .
X5OCrMnNiV229 42CrMd SOCrMo4 I7CrNihlo6
5115
16MnCrS
6152
5CCrV-l
302 316
302825 (EnSgA) -3 16s I6
05580 410 420
4lOS21 (En56A) -42OS45 (En56D)
X I2CrNi I88
exuuder barrels. non-Rturn valves Nozzle base plates Bevel gears. screw and wheel gears, shafts, chain components Helical gear wheels, guide bars, guiding collmlns Thrust plates. clamping devices. valve sprin&. spring c&t&s Screw cases, bushes
XSCrNiMo I8 IO Perforated or slotted hole screens. parts for the textile and tubber industries GXIOCrNiMol89 Valve plugs, parts forthe textileand chemical industries Valve components, fittings XIOCrl3 XjOCrl3
X3SCrMo I7 Gray and ductile cast iron
Valve components. plunger rods. fittings. guides, parts for chemical plants Shafts, spmdles, valves Parts for textile machinery, mandrels. molds, sleeves
mium. vanadium, or titanium (see Table). The operating temperature ranges from 850 to 1050 “C (1560 to 1920 “F). It is a two-step process: I. Boding by conventional methods, such as pack, paste, and electrolpic salt bath techniques 2. Dillitsing me.taliic elements through the powder mixture or borax-based melt into the borided surfaces. With the pack method, sintering of particles is avoided by passing argon or hydrogen into the reaction chamber. The mierosttucture of a borocbromtitanized alloy steel is shown in an adjoining Figure..
Quenching
and Tempering.
Borided
steels are quenched
in air, oil,
salt baths, and aqueous Polymers.
Applications Marty ferrous materials can be borided, including structural steels, tool steels, stainless steels, cast steels, Armco CP iron, gay and ductile irons,
and ferrous P/M materials. Proven applications are shown in an adjoining Table. Air-hardening steels can be simultaneously hardened and borided; waterhardening steels are not borided because of the susceptibility of the boride layer to thermal shock. Also excluded are resulfurized and leaded steels (because of tendencies toward case spalling and case cracking), and nitrided steels (due to their sensitivity to cracking).
Reference I. ASM Memls Ha&book, tional. 1991, p 137
Hear Trt~~tir~g. Vol 3, 10th ed., ASM Intema-
76 / Heat Treater’s
Laser
Guide
Surface
Hardening austenitizing temperatures without unduly affecting the bulk temperature of the workpiece. fn laser surface hardening, as in the electron beam process and high frequency, pulse hardening methods (see article on these self-quenching processes in this chapter), a quenching medium is not needed. Self-quenching occurs when the cold interior of the workpiece is a large enough heat sink to quench the hot surface by heat conduction fast enough to allow the formation of martensite on the surface.
A laser heats the surface of a part to its austenitic temperature. The laser beam is a beam of light, is easily controlled, requires no vacuum, and does not generate combustion products. However, complex optics are required, and coatings are required on surfaces to be hardened because of the ION infrared absorption of the steel, Ref I.
Characteristics Lasers are effective in selective hardening of wear and fatigue prone areas of irregularly shaped machine componems such as camshafts and crankshafts. Distortion is low. Lasers are not efficient from an energy utilizaGon standpoint. Energy efficiency may be as low as IO percem.
Operating
Applications More than 50 applications of the process have been reponed. Materials include plain carbon steels (I 010. 1050, 1070). alloy steels (4340.52 100). tool steels, and cast irons (gray, ductile, and malleable types). Reported case depths on steels run from 250 10 750 pm; those on cast irons about 1000 pm.
Information
This surface hardening process is not fundamentally different from conventional through hardening of ferrous materials. In both instances, increased hardness and strength are obtained by quenching the material from the austenite region to form hard martensne. Wilh laser hardening, however, only a thin surface layer is healed to the austenitizing temperature prior to quenching, leaving the interior of the workpiece essentially unaffected. Because ferrous materials are fairly good conductors of heat, ir is necessary IO use very intense heat fluxes to heat the surface layer to
Electron
Beam
Reference I. ASM hlerals Handbook, Hevat Trtvaring, Vol 4. 10th ed., ASM tional, 199 I, p 286
Intema-
Hardening
This is a shon surface hardening process for martensitically hardenable ferrous malerials. Energy for austenilizing is provided by electron beams, Ref I.
(see article on process in this chapter). To accommodate self-quenching, workpiece thickness should be at least 5 LO IO times the depth of austenitizing.
Characteristics
Applications Carbon, alloy, and 1001 steel applications
are listed in the adjoining
Table.
Extremely low hardening distortion and relatively low energy consumption give the metallurgist an alternative to conventional hardening processes In some instances. the technique is competitive with case hardening and induction hardening processes.
Reference
Operating
I. ASM hl.erals Handbook, Heat Treoring, Vol 4. 10th ed., ASM Intemational. 1991. p 297
Information
Typical hardening depths range from 0. I to I.5 mm (0.004 to 0.006 in.). Rapid cooling of austenite to martensite occurs mrough self-quenching
Steels Commonly Material UNS No.
Used in Electron
Beam Hardening
C
Si
Carbon and low alloy 4140 GA 1400 12 CrMo 1 1340 Cl3400 42MnV7 Exloo GS2986 IOOCr6 1015 G10150 c IS 1045 GlOjSO C-IS I070 Gl0700 Ck 67 SSCrl SOCrV J
0.38.O.-IS 0.38-0.1s 0.9s- I .os 0.17-0.19 0.42-0.50 0.650.72 0.52-0.60 0.47.0.59
0.17-0.37 0.17-0.37 0.17-0.37 0.17-0.37 0.17-0.37 0 25-0.50 0.17-0.37 0 4 max
I 60-I .90 0.20-0.45 0.35-0.65 0.50-0.80 0.60-0.80 050.8 0.7-1.1
Tool steels T31502 02 WI T72301
0.85-0.95 0.95-1.04
0.15-0.35 0.15-0.30
1.80-2.00 0.03Omax 0.030max 0.15-0.25 0.02Omsx 0.020max
AlSl
DWa)
9OMnV8 c IOOWI
(a) Deutsche tndusu-ie-Normen. ihj 0.25 max Cu
Mn
Applications P
S
Composition, ~1% hlo Cr
0.50-0.80 0.035max 0.035 max 0 90-I 20 O.lS-0.25 0.035 mx 0.027 mm 0.040 max 0.040 max 0.035 mar 0.035 max 0.035
0.035 maa 0.020 max 0.040 max 0.040 max 0.035 max _. 0.03 max
0.30 ma\ O.lOmax I .30-I .6S 0.50 mas O.lOma 0.50 max O.lOma 0.35 m;Lx 0.2-0s 0.9-l 1 ___ 0.20max
___ ,._
Ni
v
Al
cu
Ti
0.30max 0.30mcu 0.30max 0.30mrtv 0.30maK 0.3Smax 0.3max
0.06max 0.07-0.12
,,. __. _..
,,_
___
__. 0.10 max(hj
0.07-0.12
0.25 ___
_..
___ 0.02-0.05
0.35 0.3 max
0.015 0. I-O.2 .
.
Steel
Quenching
Technology
Introduction “Quenching is one of the least understood of the various heat treating technologies,” in the words of a world authority on the subject, George E. Totten of Union Carbide Chemical & Plastics Co., Inc. Other dimensions of the problem are identified in the follouing quotes from other experts: l
l
l
“Quenching is critically important, but often the neglected part of heat treating.” “Quenching is the most critical part of the hardening process... [it] must be designed to extract heat from the hot horkpiece at a rate required to produce the desired microstructure, hardness, and residual stresses.” “Distortion is perhaps one of the biggest problems in heat treating... little information on the subject has been published.”
The subject was introduced in the previous chapter by two articles on the subject: “Causes of Distortion and Cracking during Quenching” and “Stress Relief Heat Treating of Steel.” In this section, the topic is surveyed in depth in eight articles on conventional quenching processes: l l l l l l l l
Air quenching Water quenching Oil quenching Polymer quenching Molten salt quenching Brine quenching Caustic quenching Gas quenching
l l l l l l l l l l l l l
Austempering hlartempering Isothermal quenching Aus-bay quenching Spray quenching Fop quenching Cold die quenching Press quenching Vacuum quenching fluidized bed quenching HIP quenching CUtrasonic quenching Quenching in electric and magnetic fields Quenching flame and induction hardened parts Self-quenching processing-electron beam hardening, and high frequency pulse hardening
laser hardening,
Process
of Process
Air, a gas high in nitrogen,
cools by extended
vapor phase cooling.
Information
As with other quenchants. heat transfer rates are dependent on flow rate-in this instance, flow rate of air past the hot part (see Figure). Cooling can be speeded up by increasing the velocity of air 110~. but the accelerated rate is not sufficient to quench harden man) steels. The ability of air to harden plain carbon steels drops dramatically with increasing carbon content (see Figure).
Application
l
methods of quenching are discussed in articles:
I. George E. Town. preface to AShl Conference Proceedings, “Quenching and Distortion Control.” ASM International, ‘92 2. Totten et al, “Handbook of Quenchants and Quenching Technology,” ASM International. ‘93
Air is the oldest most common. least expensive quenching medium, Ref I.
Operating
l
I7 alternative
References
Air Quenching Characteristics
In addition.
Range
Air is used in quenching steel and several nonferrous metals. The comparative heat transfer coefficients of different metals as a function of surface temperature are shoun in an adjoining Figure. To get optimal hardness, it is often necessary to use a more actike quenching medium. such as brine or oil.
Reference I. Totten et al, Handbook oj Qwttclrottts ASM International. 1993
md Qutwclriny Teclrtrolog~:
Heat transfer coefficients face temperature
for air cooling as a function of sur-
78 / Heat Treater’s
Guide
Hardness values obtained with different quenching media
Cooling capacities of still and compressed air
Water
Quenching
Process
Like air, water is an old, common, inexpensive quenchant (Ref I). It is applied in several ways: in straight, immersion quenching; in a special, double-step, hot water quenching process; and in conjunction with polymer quenchants and with brine quenchants.
Characteristics
of Process
Water, especially cold water, is one of the most severe available. Vigorously agitated water produces a cooling the maximum with liquid quenchants (Ref 2). As water the vapor phase is prolonged and the maximum rate sharply (see Figure).
Operating
quenching media rate approaching temperature rises, of cooling drops
Information
l l
Maintaining water at a low temperature through cooling Vigorous agitation to disperse the vapor blanket Addition of an organic salt (see Brine Quenching)
Double-step, hot water quenching ing of steel wire. It consists of: l
l
Range
Water is the choice where a severe quench does not result in excessive distortion and cracking. Use generally is restricted to quenching simple, symmetrical parts made of shallow hardening grades of steel. Other applications include austenitic stainless steels and other metals that have been solution treated at elevated temperatures.
Effect of temperature
Generally, good results are obtained in straight immersion quenching by maintaining water temperatures in the range of I5 to 25 “C (60 to 75 “F) and by agitating water to velocities greater than 0.25 m/s (50 ft/min). Water temperature, agitation of water, and amount of contamination in the water must be controlled. The comparative cooling properties of hard water and distilled water are indicated in an adjoining Figure. The detrimental effect of temperature dependence and vapor phase stability can be minimized (Ref 3) by: l
Application
is a possible alternative
to lead patent-
Heating wire to 920 to 950 “C ( 1690 to 1710 “F) and immersing boiling hot water for an appropriate time Removing wire from water and air cooling (Ref I)
into
Source:
ES. Houghton
&
on quenching Co.
properties
of water.
Steel Quenching Technology / 79 Cooling curves for hard water and distilled water
References I. Totten et al., Handbook of Quenchanrs ASM International, 1993
Oil Quenching
and Quenching
Technology,
Process
AU modem quenching oils are based on mineral oil, usually paraffin based, and do not contain fatty oils. Usage of oils opens up a number of options for the heat treater: l l l
l
l
Normal-speed oil for treating steels high in hardenability Medium-speed oils for medium hardenability steels High-speed oils for treating low hardenability steels and for other applications Hot oil quenching (also called marquenching or martempering) provides another option Water-washable quenching oils: for removing oils on treated parts with plain water
Characteristics
of Process
Oils are characterized in various ways, depending upon operating requirements. Quenching speed and operating temperature are among these considerations. The importance of quenching speed is that it influences hardness and depth of hardening. Cooling rate curves for normal-, medium-, and highspeed quenching oils are shown in an adjoining Figure (Ref I). Cooling curves for different quenchants are given in an adjoining Figure (Ref 7). Almost all quenching oils produce lower quenching rates than water or brine solutions, but they remove heat from workpieces more uniformly than water normally does, meaning less likelihood of distortion and cracking (Ref 3). Temperature of operation is important because it influences: l l l l
2. ASM Metals Handbook, Heat Treating, Vol 4, 10th ed.. ASM lntemational. 1991 3. Houghron on Quenching, E.F. Houghton & Co., Valley Forge, PA
Oil life Quenching speed Viscosity of oil Distortion of workpieces
Effect of temperature on quenching shown in an adjoining Figure (Ref I).
speed for a hot quenching
oil is
Changes in viscosity can indicate oxidation and thermal degradation, or the presence of contaminants. Ln general, viscosity goes up as an oil degrades and can result in changes in quenching speed. Flash point, another consideration, is the lowest temperature at which oil vapors ignite in the presence of an ignition source; it is important because
Cooling rate curves for quenching oils. Source: & co.
E.F. Houghton
80 / Heat Treater’s
Guide
Cooling rates for different quenchants
Effect of temperature on quenching speed of hot oil. Source:
Characteristics
of Quenching
Oils
E.F. Houghton&Co.
‘Qpe ofoil
Bath temperature “C “F
FlZL5b point OC OF
Con\rntionaI Accelerated hlarquenching
~65
170 180 300
Use Temperatures Viscosity at 40 T U~W, SUS
Qpical viscosity at 40 OC (loooF), sus
3-m 355
105 94
570
7ocl
for Marquenching
Operating Data on the quenching oils marquenching Applications l
l
l
-IO to SO
Information use temperatures for conventional, accelerated, and mmare given in an adjoining Table and use temperatures for oils are given in a second Table (Ref 2). based on oil speed are as follows:
Normal-speed oils: used where the hardenability of a steel is high enough to provide specified mechanical properties with slow cooling. Typical applica6ons are highly alloyed steels and tool steels Medium-speed oils: typical applica6ons are medium- Lo high-hardenability steels High-speed quenching oils: for low hardenability alloys, carburized and carbonitrided parts, and medium hardenability steel parts large in cross
Elotwire test, A
16.0 IO 30
30 39 30
Oils Use temperature
hlinimum flash point OF T
250-550
“0
700 1500 2000-2800
2.50 290
130 -180 550
Protective atmosphere oc OF
Open air T 9s-150 120-175 I SO-205
OF X0-300 250-350 3OsmO
section that require very high rates of cooling cal properties it is related to the maximum safe operating temperature-usually “C (71 to 90 OF) below the open cup flash point for oil.
GM quench* meter (nickel ball) time, s
95-175 120-205 I SO-230
200-350 250-400 300-450
to get maximum
mechani-
Hot oil quenching: for applications where it is desirable tion and cracking to a minimum. It is a two-step operation: l l
l
to keep distor-
Operating temperature generally of the oil is 100 to 200 “C (210 lo 390 “F). Operating temperature is held until the temperature throughout the workpiece is uniform. Workpieces are then air cooled to ambient temperature.
References I. Houghton on Quenching, E.F. Houghton & Co., Valley Forge, PA 2. Totten et al.. Handbook oj’ Quenchants and Quenching Technology ASM International, 1993 3. ASAl Metals Handbook, Hem Trearing, Vol -I, 10th ed.. ASM lntemational. 1991
Steel Quenching
Polymer
Technology
/ 81
Quenchants
Around 20 different aqueous polymers, quenching steels (Ref I). They include:
it’s reported,
have been used in
Effect of PAG concentration
on quenching characteristics
. Polyvinyl alcohol (PVA) l Polyalkylene glycol (PAG) l Sodium polyacrylate (ACR) l Polyvinyl pyrrolidone (PVP) l Polethyl oxazoline (PEO) PAG is No. I in usage today
Characteristics Inverse solubility in water is a key characteristic of a number of polymer quenchants, including PAG’s, because this phenomenon modifies the conventional, three-stage quenching mechanism, providing flexibility in cooling rate. These polymers are completely soluble in water at room temperature, but insoluble at elevated temperatures, ranging from 60 Lo 90 “C (l-10 to I95 “F). When a hot part is fist immersed in a quenchant bath, the quenchant in the immediate vicinity of the hot metal surfaces becomes insoluble and deposits itself on the part in the form of a polymer-rich film. The tilm acts as an insulator, which slows down cooling to a rate analogous to that of oil in the vapor phase. ln a number of applications. the quenching rates of aqueous polymers are intermediate between those of water and oil (see adjoining Table). Ln stage 2 of cooling (boiling phase), the film eventually collapses and the quenchant comes into contact with the hot metal. resulting in nucleate boiling and high heat extraction rates. In the final stage, cooling is by conduction andcomection into the liquid. When metal surface temperatures fall below the inversion temperature. i.e.. 75 s, the polymer redissolves and forms a homogeneous polymer-water mixture.
Operating
Typical Quench Media
Oil Polymer Water Brine
on quenching
charac-
Information
Cooling rates can be tailored to requirements by changing the concentration of the solution, quenchant temperature. and degree of agilation of the bath. Concentration influences tilm thickness; with increasing concenfration, the maximum rate of cooling and the cooling rate in the comection phase drop (see Figure). Agitation of the quenchant has little effect during the film stage. Wettability of workpiece surfaces is improved with S% solutions of PAG, which is beneficial to quench uniformity. At this concentration, problems with soft spotting associated with water quenching are avoided. Concentrations in the IO to 20% range accelerate cooling rates to the level of fast quenching oils. These concentrations are suitable for quenching low hardenability steels requiring maximum mechanical properties. Concentrations of 20 to 308 boost cooling rates suitable for a wide range of through hardening and case hardening steels. Bath temperature has an influence on the quenching speed of solutions. The effects of three different temperatures on a 2% PAG concentration with vigorous agitation is sho& n in an adjoining Figure. The maximum cooling rate decreases with increasing temperature. PAG solutions must bs
Quenchant
Effect of PAG-water temperature teristics
Severities
Achievable
with Various Grossmann H factor 03-0.8 o.L?-I.2 0.9-1.0 2.0.5.0
1 Effect of agitation on quenching characteristics
of PAG solu- 1
82 / Heat Treater’s
Sensitivity
Guide
band for quenchant selection
Spray curtain in quenching chute
cooled to prevent them from reaching the inversion temperature. A maximum operating temperature of approximately 55 “C (130 “F) normally is recommended. Agitation has an important effect on all polymer quenchants, by ensuring a uniform temperature distribution within the bath; it also affects cooling rate (see Figure). As the severity of agitation increases, the duration of the vapor phase (tilm phase) is shortened and eventually disappears. During the convection phase, agitation has comparatively little effect. PAG’s are used in immersion quenching of steel parts, in induction hardening, and in spray quenching. Applications of other polymers include forgings, open tank quenching of high hardenability steels, use in integral quenching furnaces. patenting of high-carbon steel wire and rod, and in quenching railroad rails.
Guidelines Considerations l l l l l l
for Selecting generic to polymer
Polymers quenchants
include:
Material composition Section size of workpiece Type of furnace Quenching system design Method of quenching Distottion control
Material composition and section size play critical roles in quenchant selection (see Figure). Note that this figure provides guidelines for selecting polymer quenchants based on such considerations as hardenability of the steel, section size, quench severity factors, and polymer selection per applications. Alloy content influences hardenability, which determines the quenching speed needed to get a specified hardness and other properties.
Section size and complexity affect quenching speed requirements. Heavy section parts are quenched faster than those with thin sections to get equivalent results. Furnaces used in oil quenching may require modification for polymer quenching, and certain precautions are observed. The design of integral quench furnaces, for example, may require modification to minimize the possible effects of water vapor in furnace atmospheres. Changes include ensuring a good inner door seal and the maintenance of positive gas pressure in the hot zone. Spray curtains are needed in the quenching chutes of continuous furnaces to prevent contamination of the furnace atmosphere with water vapor (see Figure). A precaution: polymer quenching of steel parts previously treated in salt baths generally is not recommended due to the effects of the carryover of high-temperature salt. Aqueous polymer quenchants are recommended for parts treated in induction heating. Quenching system design can have an influence on quenching characteristics. Examples include design features relating to agitation, method of circulating quenchants. and fluid temperature controls. Method of quenching can directly affect cooling rates and the results obtained in quenching. Direct Quenching. This technique is commonly used in quenching with aqueous polymers in many different types of furnaces. Time or Interrupted Quenching. This technique is used to change the cooling rate during quenching, i.e.. quenching a large forging in water for a specified time, then transferring the workpiece to a polymer quenchant to reduce cooling in the convection phase. An alternative practice, used to reduce quench cracking and distortion, is to quench first in a polymer solution, followed by an air quench. In spray quenching quenchant characteristics are influenced by the volume and pressure of the quenchant and by spray nozzle design. Distortion control is needed in quenching thin or complex section workpieces. Use of a slower quenchant is one of the control techniques. References I. Totten et al., Handbook of Quenchotm and Quenching Technology, ASM International, 1993 2. Horcghron on Qrtenching. E.F. Houghton & Co., Valley Forge, PA
Steel Quenching
Molten
Salt Quenching
Characteristics Minimum quenching temperatures depend on the melting point of the salt mixture, which depends on the composition of the mixture (see Figure); the ratio of the salt mixture may also affect the viscosity of the medium, which, in turn, affects cooling.
Like all quenchants, the heat extraction capabilities of molten salt depend on the agitation rate of the bath (see Figure). Agitation is applied in several ways. One approach is shown in an adjoining Figure. In heat treating it is common for steel to be austenitized in a hightemperature salt bath composed of a binary blend of KNO3/NaNO3, or a ternary chloride blend, such as KCVLiCVNaCI. When austenitization is completed, the workpiece is quenched in a lower temperature, ternary blend of KNO~/NaN02/NaN03.
Information
Quenching temperatures of the bath range from 140 to 600 “C (285 to II IO “F), but salt melting points as low as 80 “C (175 “F) can be obtained with additions of up to 10% water. Control of bath temperature is critical (see Table). Salt baths are subject to potential explosive degradation at temperatures above 600 “C (I I IO “F). Care is also advised in making water additions, because they are accompanied by spattering of the molten salt. In one safety procedure, additions are made very slowly and bath temperatures are held below 175 “C (3-U “Fj. An automatic additive device and probe monitoring system (see Figure) is an alternative. Controlled additions of specific amounts of salt are made in a temperature range of I80 to 250 “C (355 to 180 “F). Another consideration: salt can absorb water from a humid environment at room temperature when a quenching system is not in use. Before normal operations are resumed, heating the bath to 95 “C (205 “F) until all water is removed is a general recommendation.
Effect of Salt Temperature Salt temperature T
OF
195 200 230 270 295 350
385 390 450 51s 560 660
(a) A KNO,-NtiO,
/ 83
Process
These salts usually are the medium of choice for high-temperature quenching. They are either binary or ternary mixtures of potassium nitrate (KNO3). sodium nitrite (NaNO?). and sodium nitrate (NaNO3). Ref I.
Operating
Technology
on Quench
Freezing points of ternary alkali nitrate-nitrite in percent
mixtures given
Severity(a)
Grossmann Center
H factor, hr.-r
0.46 0.45 0.40 0.45 0.4 I 0.43
Surface 0.63 0.65 0.65 0.64 0.57 058
salt with a melting point of I35 “C (275 OF) was used u ith no agi-
tation.
Degussa system for adding water to molten salt
Effect of agitation on quench severity of molten salt
84 / Heat Treater’s
Application Molten l
l l
l
l
Guide
Range
salt quenching
Dual impeller salt bath agitation system
applications
include:
Martempering and austempering (see items on both subjects in this chapter) Quenching high-alloy steels Quenching high-speed steel tools, to minimize scaling, distortion. and cracking Quenching steels such as spring wire to reduce the risk of cracking during martensitic formation Quenching to enhance the formation of high-temperature transformation products, such as bainite and ferrite.
Reference I. Totten et al., Handbook of Quet~chuttts ASM International, 1993
Brine
Quenching
curd Q~renchitrg
khnolog~~
Process
The term refers to aqueous solutions containing different percentages salts such as sodium chloride (NaCI) or calcium chloride (CaClj.
of
lently. creating turbulence high cooling rates.
that destroys
the vapor phase, resulting
in very
Characteristics
Operating
Cooling rates are higher than those of water for the same degree of agitation, or. alternately, less agitation is needed to get a given cooling rate. Higher cooling rates reduce the possibility of steam, the cause of soft spots in quenching, but higher cooling rates generally increase the likelihood of distortion and cracking. Use of baffling patterns on quench tanks and propeller agitation may be needed in quenching very lower hardenability steels (Ref 2). In quenching, minute salt crystals are deposited on the surfaces of workpieces. Localized high temperatures cause crystals to fragment vio-
Brine concentration is expressed in several ways (see Table). Both sodium chloride and sodium hydroxide. the latter a caustic solution, are covered in the Table. Brine concentrations up to 33 percent progressively reduce the vapor phase. but such concentrations generally are considered impractical. A IO percent solution of NaCl is quite effective in hardening. The relationship of brine concentration to hardness is indicated in an adjoining Figure. It is necessary to monitor brine concentration to get reproducible results in quenching. Cooling properties are not seriously alTected by small variations in the operating temperatures. Brines can be used at temperatures near that of
Relation
of Brine Density
salt, ?o NaCl solutions -I 6 8 9 IO I2
to Brine Concentration
Specitk gravity Direct reading OBk(a) hydrometer
(Ref 2)
Relation of hardness to brine concentration when stillquenching, end quench specimens 90 “C (195 “F) brine solution. Number above curves indicate distance from quenched end
Salt concentration lb/sd sir.
in UnitS Of ‘/lfj in. (Ref 2). I .026&J I.0413 I .0559 I .0633 I .0707 I .0857
3.8 5.8 7.7 8.7 9.6 II.5
11.1 62.4 81.5 95.9 107.1 130.3
0.313 OS2 I 0.705 0.800 0.89-l I.087
1.0095 I .0207 I.0318 I .04x3 I .OS38
I .-I 2.9 4.5 6.0 7.3
IO.1 20.4 31.0 -11.7 52.7
0.08-E 0. I704 0.2583 0.348 I 0.1397
NaOB solutions I 2 3 4 5
Information
(a) “Be. Baumb; specific gravity II is reading on Be scale in “Be
for liquids hea\ ier than Hater is 1154 I15 -n).
where
Steel Quenching
Technology
/ 85
Relation of hardness to distance from quenched end of specimens quenched in water and brine. Cooling power . of brine is greater than that of water at 80 “C (175 “F) (Ref 2).
boiling water, but their maximum cooling power is at a temperature of approximately 20 “C (70 “F). Effects of temperature on cooling power are indicated in an adjoining Figure. Sludge and scale should be removed from baths periodically. They can clog pumps and recirculating systems and reduce cooling rates. Excess water reduces solution strength and cooling power.
Caustic
Quenching
I. Totten et al., Handbook of Quenchnnrs and Quenching Technology, ASM International. 1993 2. ASM Merals Handbook, Hear Treating, Vol 4, 10th ed.. ASM fntemational. 1991
Process
The most common alternative to sodium chloride quenching is aqueous sodium hydroxide (a caustic) in concentrations ranging from 5 to IO percent (Ref I).
Characteristics Cooling rates are similar to those of sodium chloride at high surface temperatures. Slower cooling rates than those available with sodium chloride are obtained in the martensitic transformation temperatures for many steels (450 “C. or 660 “F), which would be expected to reduce susceptibility to cracking.
Operating
References
Information
The effect of NaOH concentration on cooling rate, at a bath temperature of 20 “C (70 “F), is shown in an adjoining Figure. The effects of I to 5 percent concentrations of NaOH are shoun in an adjoining Table. In practice, aqueous solutions are in the 5 to IO percent range. Comparatively, NaCl solutions are considered to be safer. less costly. and easier to handle than NaOH solutions. The main shortcoming of the latter is that its high alkalinity is harmful to human skin (Ref 2).
Relation of Brine Density and NaOH Solutions
Salt, 9 NaCl solutions -I 6 8 Y IO I2
NaOEl solutions I 2 3 -I 5
to Brine Concentration
Specific gravilg Direct reading “Be(a) hjdrumeter
of NaCl
Salt concentration lb/gal ks
I .0268 I.Wl3 I .055Y 1.0633 I .0707 I .0857
3.8 5.8 7.7 8.7 9.6 I IS
11.1 62.3 84.5 95.9 107.1 130.3
I.OO9.r I .0207 I.0318 I .@I28 I .0538
I .-I 2.9 4,s 6.0 7.4
10.1 20.4 3 I .o 41.7 52.7
0.343 0.52 I 0.705 0.800 0.893 I.087
0.0842 0.170-t 0.2583 0.318 I 0.1397
(a) “BC. Baumt: specific grak ity for liquids hea\ ier than \\ater is l-IS/( I45 -n). where II is reading on BP scale in “Be
88 / Heat Treater’s
Guide
Effect of NaOH concentration
on cooling rate
References I. Totten et al.. Handbook of Quenchants ASM International,
and Quenching
Technology,
1993
Gas Quenching
Heat Treating,
Vol 4, 10th ed., ASM
Interna-
Process
Atmospheres containing some hydrogen or helium are commonly used. Nitrogen is among the alternatives. Gases are also used in vacuum quenching.
Characteristics Cooling rates are faster than those in still air and slower than those obtained with oil. Austenitized workpieces are placed directly in the quenching zone and heat is extracted by a fast-moving stream of gas (Ref I).
Operating
2. ASM Metals Handbook. tional. 1991
Cooling rate is adjusted and controlled by altering the type, pressure, and velocity of the gas. In quenching, large volumes of gas are directed through nozzles or vanes to impinge on the workpiece. After the gas absorbs heat from the hot workpiece, it is cooled by being passed through water-cooled or refiigerated coils. Recirculating fans return gas to the nozzles, through which they are again directed at the workload. Quenching units are of the batch or continuous types, and the former are most commonly used.
Information
The cooling rate of the metal being treated is related to surface area and mass of a part, as well as the type, pressure, and velocity of the cooling gas.
Cooling curves in quenching air (normalizing)
4130 steel in gas, oil, and still
Brinnel hardness of forged, 1095 steel disks 100 mm (4 in. thick) after oil quenching, gas quenching (forced air), and cooling in still air (normalizing)
Steel Quenching
Application
Range
In some instances quenching in still gas is too slow and oil quenching is not desirable for such reasons as distortion, cost, handling problems, or insufficient ftnaf hardness. Quenching in a fast-moving stream of gas is a compromise. The process is used, for example, in hardening aircraft tubing, steels that are not air hardenable, and tool steels. Data on quenching 4 I30 aircraft tubing are found in an adjoining Figure. Data on steel that is not air hardenable (forged 1095 steel in this instance) are presented in an adjoining Figure. In the tool steel example, A2 and Tl, in the form of solid blocks 50 by 100 by 100 mm (2 by 4 by 4 in.), were gas quenched with cylinder nitrogen in a vacuum furnace. Cooled gas was admitted to the chamber at 69 kPa (IO psig). As indicated in an adjoining Figure, A2 was cooled from 1010 to 345 “C (1850 to 655 “F) in 8 min. and Tl was cooled from 1290 to 345 “C (2355 to 655 “F) in I3 min. In both instances, cooling rates were suitable for maximum hardness.
Reference I. ASM Metals Handbook, tional. 1991
Heat Treating,
Vol -k 10th ed.. ASM Intema-
Technology
/ 87
Surface cooling curves for blocks made of types Tl and A2 tool steels quenched from austenitizing temperatures by cooled nitrogen in a vacuum furnace
Other
Quenchants/Processes
Introduction A numher of alternatives including: l l
l l l
to standard quenchants/processes
l
frequency.
pulse hardening;
electron
or magnetic
field
Quenching
Characteristics
of Process
Alternative quenches must be used to make vacuum quenching viable. Other media include oil. aqueous polymers. and pas. Gas is the most commonly used. In fact. the fastest growing technology in heat treating is gas quenching in a vacuum furnace (Ref I).
Information,
Quenching
of Heat Transfer
Quenchant Ga.s.recirculated( 1000mbarN2~ Gzs.o~rrprcsrure. high \rlocib Salt bath (5.50 “C or 1070 “FJ Fluidizedbed ’ Stationq oil (20-80 “C. or 70. I75 “F) Recirculated oil (30-80 “C, or 70. I75 “F) \hhter( 15-25 “C.or60-75 “FJ
Coefficients
of Various
Aeat transfercoefficient( I@%I50 300400 350-450 -loo-500 100@1500 I8OO-‘100 3OOc3500
W/m?.
Vacuum Quenching
in Oil
With the exception of relatively high pressure (>20 bar) gas quenching, quench severities with _gas are limited to those up to. but usually not including. conventional oil. k’hen lovver hardenahihty alloys are heat treated in vacuum furnaces. more quench severity is needed. which is the niche for oil.
Reference I. Totten et al., Hmrdbook c$ Q~rtwctrunrs AS hl International. I993
with Gas
In this procedure. the furnace is pressurized with gas after the heat treating step is completed-this is called backfilling. The two main factors affecting quench severity are gas velocity and gas pressure (see adjoining Figures). Gas quenching usually is done with nitrogen. argon, helium. or hydrogen. Physical properties of quenching gases are listed in an adjoining Table. Recently developed applications are based on gas mixtures. such as nitrogen/helium. Gas blending is a cost-elTective way of getting heat transfer rates greater than those available uith helium alone. High pressure gas quenching (helium at a pressure of 20 bar) can produce quench severities comparable to those of conventional. recirculated oil. At very high pressures (hydrogen at SO bar) heat transfer coefficients are greater than those of eater.
Comparison Media
l
Spray quenching Fop quenching Cold die quenching Quenching in an electric
In addition. some processes are uniquely suited for quenching parts surface hardened in a specific process. such as quenchants for flame and induction hardened ~orkpieces.
Parts can he quenched,in vacuum furnaces, but heat transfer rates are relatively slob (5.7 W/mK. or 3.6 B&h “F) in comparison with those of oil. helium, nitrogen. and air (see adjoining Table and Figure, Ref I).
Operating
l l
Vacuum quenching Selfquenching processes (high karn process, and laser process) Fluidized bed quenching l~ltrasonic quenching HIP quenching
Vacuum
are availahle.
R
Quench severities of different media
nnd Qtrmchitrg
Technology,
Other QuenchanWProcesses
Physical
Properties
of Quenching
/ 89
Gases Quenching gas Nitrogen
Helium
Hydrogen
I. I 70 0.967 28.0 I.o-ll 259 x IO-’ 17.74 x lo+
0.167 0. I38 4.0026 5.1931 ISOOX lOA 19.68 x IO4
0.084 I 0.0695 2.0158 I-I.3 1869x IO-’ 892 x IO”
Mw Density,kg/m3at lS”CII bar Density ratio, v/r. to air Molar mass. kg/m01 Specific heat(a). k.lkg K Thermal conducti\ Q(a). \V/m K Dynamic viscosity(aJ, N s/m?
1.6687 I .3797 39.938 0.5204 177 x IO-’ 22.6 x IO”
Ia) Gas conditions. 35 “C. I bar
Effect of chamber pressure at constant volumetric cooling time
Self-Quenching
rate on
Effect of volumetric
flow rate of gas at constant density on
Processes
In this category are high frequency pulse hardening (Ref I ), electron beam, and laser processes (Ref 7). Self-quenching occurs when the cold interior of a Horkpiece is a sufficiently large heat sink to quench hot surfaces hq heat conduction to the interior at a rate fast enough to allo\\ martensite to form at the surface. Heat sources are the laser. electron beam. and inductive electric heating. In pulse hardening wjth induction heating, for example. power density is up to about 300 W/mm-. and heat treatment is in the millisecond rangs (Ref I). With each process, areas treated are small and part size can be a restriction.
Applications Lasers. Materials hardened include plain carbon steels ( IO-IO, 1050, 1070). alloy steels (4340. X!lOO,, tool steels, and cast irons (pm!. ductile. and malleable). Examples include selectike hardening of irregularly shaped parts like camshafts and crankshafts. which are subject to wear and have fatigue-prone areas (see adjoining Figure. Ref Zj. Electron Beam. Commonly used steels are listed in an adjoining Table. Typical parts are shown in an adjoining Figure (Ref I?).
Area treated on ductile iron camshaft is indicated (Ref 2)
90 / Heat Treater’s
Guide
Pulse Hardening. Selectively hardened parts include saws (in an adjoining Figure, Ref I). circular saw blades, and punching tools, plus precision engineering components for the electrical and textile industries (see Figure, Ref I). Also, this process produces very fine, acicular structures that add corrosion resistance to a part.
References I. G. PIBger, “HF Pulse Hardening in the Millisecond Range,” ASM Conference Proceedings, Quenching and Dbronion Control, ASM Intemational. I992 2. ASM Memls Hundbook, Hear Treoring. Vol4. 10th ed., ASM Intemational. 1991
Typical components heat treated with electron beam hardening method. (a) Rollerbearing element support. (b) Selected components used for both linear and rotary motion applications. Courtesy of Chemnitzer Werkzeugmaschinen GmbH (Ref 2)
Hardened teeth on band saw blade (Ref 1)
Samples of textile industry parts (Ref 1)
Steels Commonly AIs1
Material UNS No.
Used in Electron
Carbon and low alloy GJl400 12CrMa-l -II40 1340 ES2100 1015 IO45 I070
Gl34OO GS2986 G10150 G lO4SO Gl0700
C
DtN(a)
Beam Hardening Si
Applications
hln
P
s
Composition, wt % Cr hlo
QMnV7 IOOCr6 c I5 c-is Ck67 55CrI SOCrV 1
0.X3-0.45 0.38-0.45 0.95-1.05 0.12-0.19 0.12-0.50 0.65-0.72 0.52-0.60 0.37.0.55
0.17-0.37 0.17-0.37 0.17-0.37 0.17-0.37 0.17-0.37 0.15-0.50 0.17-0.37 O.-l max
0.50-0.80 1.60-1.90 0.20-0.15 0.35-0.6.5 O.SO-0.80 0.60-0.80 0.5-0.8 0.7-I. I
0.03Smax 0.03Smax 0.027 max O.O-lOmax 0.04Omax 0.03Smax 0.03.5 max 0.035
0.035 max 0.035max 0.020max O.O-K)ma.\ O.O-!Omax 0.035 max 0.03 max
0.90-1.10 0.30max 1.30-1.65 O.SOmax OSOmax 0.3Smas 0.2-0.5 0.9. I .2
9OMnV8 c IOIIWI
0.8.5-0.9.5 0.95-1.04
0.15-0.35 0.15-0.30
I 80-2.00 0.15-0.25
0.030max 0.02Omax
0.030max 0.020mai
.._ 0.20max
O.iS-0.2s O.lOmax O.lOmax O.lOmax
Ni
0.3Omax 0.30max 0.30max 0.3Omax 0.30max 0.35 mar 0.3max
v
(a) Deuwhe
T31.502 T72301
Industrie-Normen.
(bj0.25
max Cu
Ti
0.25
__. 0.02-0.0s
0.07-0.12 0.20maxfb)
Cu
0.06max 0.07-0.12
Tool steels 02 WI
Al
0.35 0.3 max
0.015 0. I-O.2
Other Quenchants/Processes
Fluidized
Bed Quenching
Nitrogen and air are common quenching media. Other quenchants are argon, carbon dioxide, helium, or hydrogen. Critical variables are rate of fluidizing gas flow and thermal conductivity of the gas.
Characteristics
/ 91
of Process
Control over quenching with this process CompXes favorably with that of other liquid quenchants. The heat transfer mechanism is uniform throughout the entire temperature range. and is dominated by the properties of the gas phase. Quench rates are reproducible, do not degrade with time. and can be adjusted within wide limits and operate over a wide temperature range (Ref I ). The quenching or heat treating rate can be adjusted by altering operating conditions of the fluid bed. Variables include particle size and volume (aluminum oxide is preferred). rate of fluidizing gas flow, and the thermal conductivity of the gas. Nitrogen usually is the choice. Quench seberitics are between those of still air and slow air.
Comparisons of quenching rates for fluidized beds operating on nitrogen, and vacuum furnaces operating at 2 bar and 6 bar quench pressures at temperatures up to 575 “C (1065 oF)
In comparison with other heat treating/quenching processes, the fluid bed is less sensitike to load densit) and part geometry. Because of the liquidlike characteristics of the fluid bed. parts are surrounded by aluminum oxide particles. and the high heat capacity of aluminum oxide does not require complete gas flow over all surfaces because heat is removed by conduction.
Operating
Information
In treating H-I I and H- 13 forging dies the following (Ref I): Preheat work to 595 “C ( I I05 “Fi Austenitize at IO-10 “C (I905 “F) l Step quench at 595 “C (I IO5 “F) 9 Fluid bed quench at ambient temperature 290 “C (555 “F) l Air cool to room temperature
procedure
was used
l l
for 5 to 7 min at approximately
A second, two-stage process: quenching in helium first, followed by quenching in nitrogen. Application: austempering 4340. medium carbon steel tools. replacing salt processing. i.e., austenitizing at 920 “C (1690 “F) and quenching into salt at 330 “C (610 “F). then holding for 30 min. For the two-stage process. the quench temperature was reduced from 330 “C (625 “F) to 295 “C (565 “F). Step NO. 1: Short pulse (30 to 60 s) of helium to drive the load past the nose of the cooling curve. (In treating 4340, the fust IO s of the cooling curve is critical). Beyond this point allowable time is increased. Step NO. 2: Gas is switched from helium to nitrogen for the remainder of the cycle. In cases u here hardness values in fluidized bed quenching are slightly lower than those of the other quenchants, higher hardness can be obtained by slightly decreasing fluidized bed temperatures.
Range
of Applications
Standard and special fluid bed processes are available. Air hardening tool steels. for example, are within the range of the former, while medium and low allo) steels are among the applications of the latter. Standard Process. Performance of this process in treating air hardening tool steels is said to compare favorably with that of high pressure gas quenching in a vacuum furnace. In this instance. two critical factors are: the quench rate must be severe enough to effect full metallurgical transformation of thick sections. Chile not causing severe distortion or cracking.
COmpariSOn of results in quenching and normalizing normalized. Specimens were 12.6 mm (0.50 in.) diameter
with: A, salt solution; bars.
B, agitated
water;
C, still water;
D, oil; E, fluidized
bed; F,
92 / Heat Treater’s
Guide
Quenching rates for the fluid bed process and those for high pressure gas quenching in vacuum are compared in an adjoining Figure. The fluid bed rate is slightly higher than that at 6 bar quench pressures. The material is M-2 high speed tool steel. Other comparisons are made in a second Figure. Special Process. The standard fluidized bed has insuffwient heat transfer characteristics to be useful in quenching medium to IOU allo] steels because the critical portion of their cooling cycle is the first IO s. which precludes the application of a number of these alloys in austempering. marquenching, and direct hardening. This limitation is bypassed by modifications in the standard process. Quenching speeds are significantly higher. The special process has t&o phases. In the first phase, helium replaces nitrogen for cooling in the critical portion of the cycle (the nose of the isothermal transformation cycle). Helium has a gas conductivity nearly six times that of nitrogen. and the fluidization rate is doubled. The helium phase takes 30 to 60 s. In the second phase, nitrogen replaces helium for the rest of the cycle. Example of an Application: nustempering 4310 steel tools. In salt processing. parts were austenitized at 920 ‘C (1690 “F). and they \ierc quenched in salt at 315 “C (600 “F). then held at that temperature for 30 min. In processing uith the modified fluid bed process. the austemperinp quenching temperature was reduced from 3 I5 to 295 “C (600 to 565 “F). Hardness of these parts was lower than that of those treated ~rith the salt
Ultrasonic Virtually
of Process
Vapor blanket formation Figure).
Operating
52 100, bearing races. oil quenched 1340, wood routing bits, austempered at 350 “C (660 “F) Modified S-3. screw driver bits austempered at 3 I5 “C (600 “F) O-l, general tooling. marquenched in salt at 210 “C (410 “F) Ductile iron. crankshaft. oil quenched 86B-lO. forging, oil quenched 5 150, machined parts. oil quenched
Reference I. A. Dinunsi, “AdLances Conference Proceedings. ternational. I992
in Fluidired Bed Quenching,” p 71. ASM Qutvrchittg md Disronion Conrtd, ASM In-
Other References l
l
Totten et al., Hmdbook AShl International .4W Aie~l~ls Hntdbook. tional
oj Qrret~chatrrs Hear Twctrittg.
md
Qwm-hittg
Technology
Vol 4. 10th ed.. ASM
Intema-
Quenching
any liquid quenching medium can be used in ultrasonic quenching.
Characteristics
process. The desired result H;LS obtained by slight reductions in the fluid bed temperature. Steel parts treated by this process and prior quenching techniques include the foIloH ing:
is readil)
interrupted
by ultrasonic
energ! (see
Reference I. Totten et al.. Hmcibook of Quettchcwts AShl International. 1993
and Quenching
Technology,
Information
Ultrasonic agitation substantially increases quench severit) (see Table). but the cracking and distortion that can be caused b>, oil, Water, or brine quenchants often are eliminated. Reductions in distortlon and cracking are often accompanied by an increase in hardness.
Grossmann H Values of Various without Ultrasonic Energy Quenchant
Quenchants
with and
Gmssmann H value
Oil Still quench Violent agitalion llltra.sonic agitation
0.2YO.30 0.80/1.10 I .bS
Brine Still quench Violenr agitation Uluasonic agitalion
2.0 s.0 7.5
Hot salt at (400 OF) Still quench Violenl agitation llluasonic agifation
0.30 I.20 1.80
Comparison of vapor blanket phases during oil quenching and ultrasonic quenching
Other QuenchanWProcesses
/ 93
HIP Quenching The HIPquencher is an offshoot of the more familiar hot isostatic press used to densify metal powders and ceramics and to improve certain properties of castings. Gas (usually argon) is the only cooling medium in HIPquenching. Rapid cooling is obtained with high pressure gas at 800 to 1800 bar. Heated gas is cooled in a heat exchanger. Gas pressure pushes gas atoms closer together, increasing the number of atoms that remove heat from steel surfaces. The heat exchanger is located in the HIP vessel outside the hot zone.
Characteristics
of Process
The extremely high heat transfer coefficient of gas under high pressure makes for less variation in temperature in different areas of a part. reducing the likelihood of distortion. Characteristics of several different quenching methods are compared in an adjoining Table. The heat transfer coefficient of the process is of the same magnitude as that for the fluidized bed and about three times greater than that for the vacuum furnace (see Figure). Gas temperature is closely controlled by computer as a function of time.
Applications Higher hardenability are in the applications ment can be combined
steels such as high speed steels and other tool steels range of the process. Densiftcation and heat treatin a single operation.
Heat transfer coefficients
Spray
References I. Bergman and Segerberg. “HIP Quencher for Efftcient and Uniform Quenching.” and Segerberg. ASM Conference Proceedings, Qumching and Disioniotr Cotlrrd. AShl International, I992 1. A. Traff. M~!nl Powder Repon, 15 (199Oj, 1 3. ltdus~rial Qutwchitrg Oils-Dt~rennitlnrion of Coolitrg Ctraracreristics-Lahomroy T&r Mrrhod. Draft international standard ISO/DIS 9950. International Organization for Standardization (submitted 1988). 1. S. Segerberg, n/F‘-mpporr 920-71. n/F, Giiteborg, Sweden
Characteristics Method of quenching Vacuum Sah halh Fluidizrd bzd HIPquencher
of Four Quenching Temperature of quenchant, OC
Methods Gas
60
Nitrogen
230 20 Drlcrrasing from 1000
Nitrogen Argon
PMSU~, bar
Refl
of different quenching methods (Ref 1)
Quenching
Process
High pressure streams of quenching fluids arc directed onto areas of a uorkpiece requiring higher cooling rates. Quenchant droplets formed by the spray account for the speedup in cooling rate. Lou pressure spraying. providing a flood-type now, is preferred in quenching with some aqueous
polymers. Spray nozzles are located on a quench rig. Quenching characteristics can be innuenced by volume and pressure of the quenchant. as well as the design of spray nozzles.
94 / Heat Treater’s
Guide
Fog Quenching
Process
A tine fog or mist of liquid droplets in a gas carrier is the cooling agent. Cooling rates are lower than those in spray quenching because of the relatively low liquid content of the stream.
Cold Die Quenching Llsed for parts such as thin disks and long. slender rods that distort excessively when quenched in conventional liquid media. Quenching is between various forms of cold, flat, or shaped dies, which usually are in a press close to austenitizing operations.
Quenching
in an Electric
of Process
In quenching in an electrical field, uniformity of surface heat transfer is enhanced by destabilizing vapor blanket cooling by passing an electrical current through the workpiece.
Operating
I. ASM Mrrals Haruibook, Hear Treating, tional. I99 I
or Magnetic
In quenching steels in an electrical field, electrical current is passed through the part while it is submerged in a liquid such as oil or water. In quenching in a magnetic field. steel is quenched into an aqueous suspension of IO nm magnetic particles.
Characteristics
Reference
Information
It has been demonstrated. for example that the hardness of a 0.15 percent carbon steel can be increased IO to I8 HRC, while quench-induced microstresses are virtually eliminated (see Figure). Similar results have been obtained in magnetic field quenching. Cooling rates throughout the quench can be controlled by the concentration of magnetite particles and the force of the magnetic field (Ref I .4).
References I. Totten et al., Handbook qf Q~tetrchatm and Qttenctring Techtwlog?; ASM International, I993 2. A.A. Skimbov. LA. Kozhukhar. and N.N. Morar. So\: Eng. Ai~p/. Necrrochem, Vol 2, 1989, p 136-138 3. A.A. Skimbov, LA. Kozhukhar. and N.N. Morar. Elekrrontray Obrab. MareI. Vol2, 1989. p 87-88 1. S.N. Verkhovskii. L.I. Mirkin. and A.Ya. Simonovskii. Fi:. Khitn. Obrab. Mares:, Vol2. 1990, p I27- I32
Vol 4. 10th ed., ASM
fntema-
Field
Microstresses on perimeter of 0.45 percent carbon steel quenched in different media (Ref 1)
Other QuenchanWProcesses
Quenching
Flame
and Induction
Water is the common quenchant for flame and induction hardened workpieces. Other media are oil, soluble oil, compressed air. aqueous polymer solutions. and brine (Ref I).
Characteristics
Parts
Reference I. ASM Metals Handbook, tional, 1991
Hear Treating.
Vol 1. 10th ed., ASM Interna-
of Process
Water is the choice unless metallurgical severe quenching media.
Operating
Hardened
/ 95
considerations
call for less
Information
Open and submerged spray systems generally are used in conjunction with induction hardening. Spray oriftces for water quenching are relatively small to maximize cooling rates. Different orifice sizes and spray pressures are required in quenching with aqueous polymers. High pressure and fine spray cause premature rupture of polymer films on hot metal surfaces, which reduces cooling rates. Recommended orifice sizes and fluid pressure for quenching steels from an austenitizing temperature of 845 “C (I 555 “F) with polyethylene glycol (PAG) are listed in an adjoining Table (Ref I).
Recommended Orifice Sizes and Fluid Pressures Induction Spray Systems Orifice diameter
-m(b) Tjpe ofsprq Q-=n Submerged
(8)
for
kPa
psi
mm
in.
ZlS
-Ml
3.2 6.1
‘4 ‘4
(a) All of the cooling c‘urves for the quench factor correlation were determined using AlSl bpe 30.4 stainless steel prohes. thy Data for LJCON (Union Carbide Chemicals and Plastics Company. Ins JQuenchant B
Tempering Conventional
Processes/Technology
Processes
Tempering is a process in which previously hardened or normalized steel is usually heated to a temperature hclocr the IOU er critical temperature and cooled al a suilable rate. primarily to increase ductility and toughness. hut also to increase the grain size of the matrix. Steels are tempered b) reheating after hardening to obtain specific Lalues of mechanical properties and also to relieve quenching stresses and to ensure dimensional stahilitj. Tempering usually follows quenching from above the upper critical temperature; hoNever, tempering is also used to relieve the stresses and reduce the hardness developed during ueldinp and to relisve stresses induced b) fomling and machining.
Principal
Variables
Variables that affect the microstructure a tempered steel include: l l l
Tempering temperature Time at temperature Cooling rate from the tempering
Typical
Hardnesses
Grade
Carbon content, k
Carbon 1030 I040 1050 lob0 1080 IO??5 11.37 IIJI 1131 Alloy
SO 51 s2 56 57 ss 44 19 55
steels, water
hardening
0.30 0.30 0.30 0.30 0.30 0.30
47 47 47 47 37 47
Alloy
steels, oil hardening O.-IO
4140 4340 ul-lo 8740 4150 5150 6150 8650 8750 9850
0.40 0.10 O.-IO 0.40 0.50 0.50 OS0 050 o.so 050
260 ‘=C (500°F)
carbon content, alloy content, and
ln a steel quenched to a microstructure consisting essentially of martensite, the iron lattice is strained b) the carbon atoms, producing the high hardness of quenched steels. Under certain conditions. hardness may remain unaffected hy tempering or may even be increased as a result of it. For example, tempering a hardened steel at I eq low tempering temperatures may cause no change in hardness but may achieve a desired increase in yield strength. Also, those allo) steels that contain one or more of the carhide-forming elements (chromium. molybdenum. vanadium. and tungsten) are capable of secondq hardening: that is. they ma) become somewhat harder as a result of tempering. The tempered hardness \ alues for se\ eral quenched steels are presented in an adjoining Table. Temperature and time are interdependent variables in the tempering process. Within limits. lowering temperature and increasing time can usualI! produce the same result as raising temperature and decreasing time. However, minor temperature changes have a far greater
315T (6OOT)
37OT (700°Fj
J25T
temperiag for 2 hat 48OT -540 T
595 T
650 T
@OO°F) (9OO’=F)(lOOO°F) (1100°F) (1200°F)
Heat treatment
hardening
1330 2330 3130 1130 Sl30 8h.30
0.10
of
Composition of the steel. including residual elements
Carbon and Alloy Steels after Tempering Hardness, HRC, after
0.30 0.40 0.50 0.60 0.80 0.95 0.30 O.-IO 0.40
1340
properties
temperature
of Various
205 T (.WO”F)
steels, water
31-U)
and the mechanical
l
57 55 57 55 51 57 56 57 58 ss 56 51
45
13
48 50 ss 55 57 42 46 so
46 16 SO SO 51 40 13 47
39 42 4-l 42 43 -17 37 II 4s
31 37 40 38 II 43 33 38 39
28 30 37 37 40 -12 30 31 32
9513) Normalized at 900°C (1650°F). waterquenched from 830~X-iS“C( l525-15SO”F):s~eragedea point. 94cIJ 72 16”Cl60”F, Normalized a~885 “C I I625 “F). water quenched From 26 7’ 800-81.5 “C (1175.15OO”F):a\rrage dew poim. ;; 7“Ct4S”F) 91ta1 Normali~dur 900 “C Il650”F~. waterquenched from 830-855 “C 1 I SZS- I S7S “F); average dew point. 943)
‘5 ‘7 31 3s 39 -II 27 28 29
97w
I6
I6 I6 22 ‘2 22
s3 52 s3 5’ ii 53 55 55 57 5-l 55 5.3
50 49 50
46 17 17
4-t -II 15
II 37 41
38 33 36
35 30 33
so 50 50 53 52 53 s2 5’ ii
17 48 17 51 19 SO 49 51 18
42 45 +I 17 45 46 4s 46 1s
40 41 II 46 39 1’ -II 4-t II
37 39 38 43 3-I 40 37 39 36
3-l 31 35 39 31 36 32 3-t 33
Data were obtained on 25 null t I in.) bars adequateI) quenched wdc\elop
full hzdnejs. (a~ Hardness. HRB
31 16 19 31 27 37 ii 18 31 28 3’ lo
lB”Cl55”F1
at 900 “C ( 1650°F). water quenched fmm 800-815 “C(I-175-1500”F):a\er~gedew point, 16”Ct6O”F) Normalized at 88S “C ( 1625 OF),water quenched from 8004355 “Cl l-l7S-lS7S “F);areragedew point. Normtired
I6 “C (60 “F)
Normalized at 870 “C t 1600 “F). oil quenched hum X30-849 “C I ISIS- I550 “F); average dew point. l6’>C (60°F) Normalized at 870 “C (1600 “F). oil quenched from 830-845 “C ( 1525. I575 “F): average dew point. I3 “C (5.5 “F) Normalizcda1870”C( 1600”F),oiIquenchedfrom 830-870 ‘C t I SZS-I600 “F); aLerage deu point. 13”CtSS’F) Normalized at 870 “C ( 1600°F). oil quenched from 8 1%845 “C t IYJO- lSSO”F): average dew point. 13”C155”F,
Tempering
effect than minor time changes in typical tempering operations. With few exceptions, tempering is done at temperatures between 175 and 705 “C (315 and I300 “F) and for times from 30 min to 1 h. Structural Changes. Based on x-ray, dilatometric. and microstructural studies, there are three distinct stages of tempering, even though the temperature ranges overlap (Ref I-4): l
l
l
Stage I: The formation of transition carbides and lobering of the carbon content of the martensite to 0.1SQ ( 100 to 250 “C, or 310 to 480 “F) Stage II: The transformation of retained austenite 10 ferrite and cementite (200 to 300 “C. or 390 to 570 “F) Stage IfI: The replacement of transition carbides and low-temperature martensite by cementite and ferrite (250 to 350 “C. or 180 to 660 “F)
An additional stage of tempering (stage IV). precipitation of fineI> dispersed alloy carbides, exists for high-alloy steels. It has been found that stage I of tempering is often preceded by the redistribution of carbon atoms. called autotempering or quench tempering, during quenching and/or holding at room temperature (Ref 5). Other structural changes take place because of carbon atom rearrangement preceding the classical stage I of tempering (Ref 6,7). Dimensional Changes. Martensite transformation is associated with an increase in volume. During 1empering. martensite decomposes into a mixture of ferrite and cementite with a resultant decrease in volume as tempering temperature increases. Because a 100% martensitic structure after quenching cannot always be assumed, volume may not continuous11 decrease with increasing tempering temperature. The retained austenite in plain carbon steels and low-alloy steels transforms to bainite with an increase in volume, in stage II of tempering. When certain alloy steels are tempered. a precipitation of finely distributed allo) carbides occurs. along with an increase in hardness, called secondq hardness, and an increase in volume. With the precipitation of allo) carbides. the MS temperature (temperature at which martensite starts to foml from austenite upon cooling) of the retained austenite will increase and transform to martensite during cooling from the tempering temperature. Tempering Temperature. Several empirical relationships have been made between the tensile strength and hardness of tempered steels. The measurement of hardness commonI> is used to evaluate the response of a steel to tempering. An adjoining Figure shous the effect of tempering
Effect of tempering
temperature
of 1050 steel that was forged heat: 0.52% C, 0.93% Mn
on room-temperature
to 38 mm (1 SO in.) in diameter,
mechanical then water
Processes/Technology
/ 97
temperature on hardness, tensile and yield strengths, elongation, and reduction in area of a plain carbon steel (AISI 1050) held at temperature for I h. It can be seen that both room-temperature hardness and strength decrease as the tempering temperature is increased. Ductility at ambient temperatures. measured by either elongation or reduction in area, increases with tempering temperature. hlost medium-allo) steels exhibit a response to tempering similar to that of carbon steels. The change in mechanical properties with tempering temperature for 4330 steel is shorn n in an adjoining Figure. There is no decrease in ductility in the temperature range of tempered martensite embrittlement. or ThIE (also known as 160 “C [SO0 “F] embrittlsment or one-step temper embrittlement) because the tensile tests are performed on smooth. round specimens at relatively low strain rates. Home\sr. in impact loading. catastrophic failure may result when alloy steel is tempered in the tempered martensite embrittlement range (260 to 370 “C. or SO0 to 700 “F). H’hereas elongation and reduction in area increase continuously with tempering temperature. toughness. as measured by a notched-bar impact test. \ aries uith tempering temperature for most steels, as shown in an adjoining Figure. Tempering at temperatures from 260 to 320 “C (500 to 610 “F) decreases impact energy to a value below that obtained at about IS0 “C (300 “F). Above 320 “C (610 “F), impact energy again increases mith increasing tempering temperature. Both plain carbon and alloy steels respond IO tempering in this manner. The phenomenon of impact energy centered around 300 YY (570 ‘Fj is called tempered martensite embrittlement (ThlE) or 160 “C (SO0 “F) embrittlement. Tempering Time. The difision of carbon and alloying elements necessarj for the formation of carbides is temperature and time dependent. The effect of tempering time on the hardness of a 0.828 C steel tempered at various temperatures is shown in an adjoining Figure. Changes in hardness are approximateI) linear over a large portion of the time range when the time is presented on a logarithmic scale. Rapid changes in room temperature hardness occur at the start of tempering in times less than IO s. Less rapid. but still large. changes in hardness occur in times from I to IO min. and smaller changes occur in times from I IO 2 h. For consistency and less dependency on variations in time. components generally are tempered for I to 2 h. The levels of hardness produced by very short tempering cycles,
properties
of 1050 steel. Properties
quenched
and tempered
at various
summarized temperatures.
are for one heat Composition of
98 / Heat Treater’s
Guide
Effect of tempering temperature on the mechanical properties of oilquenched 4340 steel bar. Single-heat results: ladle composition, 0.41% C. 0.67% Mn, 0.023% P, 0.018% S, 0.26% Si, 1.77% Ni, 0.78% Cr, 0.26% MO; grain size, ASTM 6 to 8; critical pointsAc,, 770°C (1420”F);Ar,, 475°C (890°F); Ar,, 380°C (720 “F); treatment, normalized at 870 “C (1600 “F), reheated to 800 “C (1475 “F), quenched in agitated oil; cross section, 13.46 mm (0.530 in.) diam; round treated, 12.83 mm (0.505 in.) diam; round tested; as-quenched hardness, 601 HB. Source: Ref 8
Notch toughness as a function of tempering temperature for 4140 (UNS G41400) ultrahigh-strength steel tempered 1 h
Alloy Content
Carbon Content
The main purpose of adding alloying elements to steel is to increase hardenability (capability to form martensite upon quenching from above its critical temperature). The genera) effect of alloying elements on tempering is a retardation of the rate of softening, especially at the higher tempering temperatures. Thus. to reach a given hardness in a given period of time, alloy steels require higher tempering temperatures than do carbon steels. Alloying elements can be characterized as carbide forming or non-carbide forming. Elements such as nickel, silicon, aluminum. and manganese, which have little or no tendency to occur in the carbide phase, remain essentially in solution in the ferrite and have only a minor effect on tempered hardness. The carbide forming elements (chromium, molybdenum. tungsten, vanadium, tantalum. niobium, and titanium) retard the softening process by the formation of alloy carbides. Strong carbide-forming elements such as chromium, molybdenum, and vanadium are most effective in increasing hardness at higher temperatures above 205 “C (100 “F). Silicon was found to be most effective in increasing hardness at 3 I5 “C (600 “Fj. The increase in hardness caused by phosphorus, nickel. and silicon can be attributed to solid-solution strengthening. Manganese is more effective in increasing hardness at higher tempering temperatures. The carbide-forming elements retard coaJescence of cementite during tempering and foml numerous small carbide particles. Under certain conditions, such as with highly alloyed steels, hardness may actually increase. This effect, mentioned previously. is known as secondary hardening. Other Alloying Effects. In addition to ease of hardening and secondary hardening. alloying elements produce a number of other effects. The higher tempering temperatures used for alloy steels presumably permit greater relaxation of residual stresses and improve properties. Furthermore, the hardenability of alloy steels requires use of a less drastic quench so that quench cracking is minimized. However, higher hardenability steels are prone to quench cracking if the quenching rate is too severe. The higher hardenability of alloy steels may also permit the use of lower carbon content to achieve a given strength level but with improved ductility and toughness. Residual Elements. The elements that are known to cause embrittlement are tin. phosphorus. antimony, and arsenic.
The principal effect of carbon content is on as-quenched hardness. An adjoining Figure shows the relationship between carbon content and the maximum hardness that can be obtained upon quenching. The relative difference in hardness compared with as-quenched hardness is retained after tempering. An adjoining Figure shows the combined effect of time. temperature, and carbon content on the hardness of three carbon-molybdenum steels of different carbon contents. Another Figure shows the hardness of these steels after tempering for I h. as a function of tempering temperature. The effect of carbon content is evident.
furnaces or in molten salt. hot oil. or molten metal baths. The selection of furnace type depends primarily on number and size of parts and on desired temperature. Temperature ranges. most likely reasons for use. and fundamental problems associated with four types of equipment are given in an adjoining Table. Selective tempering techniques ;LTeused to soften specific areas of fully hardened parts or to temper areas that were selectively hardened previously. The purpose of this treatment is to improve machinability, toughness, or resistance to quench cracking in the selected zone.
such as in induction tempering, would be quite sensitive to both the temperature achieved and the time at temperature. By the use of an empirical tempering parameter developed by Holloman and Jaffe (Ref IO), the approximate hardnesses of quenched and tempered low- and medium-alloy steels can be predicted. Reasonably good correlations are obtained except when significant amounts of retained austenite are present. Cooling Rate. Another factor that can affect the properties of a steel is the cooling rate from the tempering temperature. Although tensile properties are not affected by cooling rate. toughness (as measured by notchedbar impact testing) can be decreased if the steel is cooled slowly through the temperature range from 375 to 575 “C (705 to 1065 OF). especially in steels that contain carbide-forming elements. Elongation and reduction in area may be affected also. This phenomenon is called temper embrittlement.
Tempering Procedures Bulk processing may be done in convection
Tempering
Effect of time at four tempering temperatures on room-temperature
Processes/Technology
/ 99
hardness of quenched 0.82% C steel. Note nearly straight lines
on logarithmic time scale. Source: Ref 9
Relationship between carbon content and room-temperature hardness for steels comprising 99.9% untempered martensite
Temperature Ranges and General Conditions Four Types of Tempering
PP of
Temperature range OC OF
equipment
Comection furnace
SO-750
Salt bath
l6O-7SO 320. I380
I70- I380
Oil hath
<‘TO --_
S-l-180
Molten meud bath
>390
>735
of Use for
Service conditions For large volumes of nearly common parts: variable loads m&e control of lemperattw moredifficul~ Rapid. uniform heating; low to medium volume; should not be used for parts whose configurations make them hard toclean Good if long exposure is desired; special ventilation and fire control are required Very rapid heating: special fixhning is reauired (high densiw)
For certain steels, the tempering mechanism is enhanced by cyclic healing and cooling. A particularly important procedure employs cycles between subzero temperatures and the tempering temperature to increase the transformation of retained austenite. The term used for this procedure. multiple tempering, is also applied to procedures that use intermediate thermal cycles to soften parts for straightening prior to tempering.
Cracking Induction and flame tempering are the most commonly used seleclive techniques because of their controllable local heating capabilities. Immersion of selected areas in molten salt or molten metal is an alternative. but some control is sacriliced. Special processes that provide specitic properties. such as those obtained in steam treating or the use of protective atmospheres. are available.
in Processing
Because of their carbon or alloy contents, some steels are likely to crack if they are permitted to cool to room temperature during or immediately following the quenching operation. Causes include high tensile residual stresses generated during quenching due to thermal gradients. abrupt changes in section thickness, decarburization, or other hardenability gradients. Another potential source is cracking due to quenchant contamination and the subsequent change in quenching severity.
100 / Heat Treater’s
Guide
Accordingly. for carbon steels containing more than 0.4% C and alloy sleek containing more than 0.35% C. transfer of parts to tempering furnaces hefore they cool to below 100 to IS0 “C (210 LO 300 “F) is recommended. Alternately, quenching oil may he used in tempering operation (martempering), or 10 avoid cooling below I25 “C (255 “F). Steels that are known to be sensitive IC) this type of cracking include 1060. 1090. 1340, 1063.4 I SO. 3340,52 IOO,6 I SO. 8650, and 9850. Other carbon and alloy steels generally are less sensitive to Uris type of delayed quench cracking but may crack as a result of part configuranon or surface defects. These steels include 1030. 1050. I I-II. I I-L!. -W7.-ll32. -I I10.4640.8632.8710. and 9840. Some steels, such as 1020. 1038, I IX. 1130. 5 130. and 8630. are not sensitive. Before being lempered. parts should be quenched to room temperature to ensure the transformation of most of the austenhe to martensite and to
Effect of tempering time at six temperatures on room-temaerature hardness of carbon-molybdenum steels with differznt carbon contents but with prior martensitic structures
achieve maximum as-quenched hardness. Austenite retained in low-alloy steels will. upon healing for tempering, transform to an intermediate structure. reducing overall hardness. However. in medium- to high-alloy steels containing austenite-stabilizing elements (nickel. for example). retained austcnite may transform LOmartensile upon cooling From tempering, and such steels may require additional tempering (double tempering) for the relief of transformation stresses.
Temper Embrittlement When carbon or low-alloy steels are cooled slowly from tempering ahove 575 ‘C ( 1065 “F) or are tempered for extended times between 375 and 575 “C (70s and 1065 “F). a loss in toughness occurs that manifests itself in reduced notched-bar impact strength compared IO that resulting from normal tempering cycles and relativelv fast cooling rates. The cause of temper embrinlement is belkved 10 be the precipitation of compounds containing trace elements such as tin, arsenic. antimony, and phosphorus, along with chromium and/or manganese. Although manganese and chromium cannot he restricted. a reduction of the other elements and quenching from ahove 575 “C (I065 “F) are the most effecuve remedies for this type of embrittlement. Steels that have been embrittled because of temper embrinlement can he de-embritkd by heating 10 about 575 ‘C ( 1065 “F). holding a few minutes. then cooling or quenching rapidly. The time for de-embrittlemen~ depends on the alloying elements presenr and the temperature of reheating (Ref I I).
Blue Brittleness The heating of plain carbon steels or some alloy steels to the temperature range of 230 to 370 ‘C (-US to 700 “F) ma,y.result in increased tensile and yield strength. as well as decreased ducuhty and impact strength. This embrittling phenomenon is caused by precipitation hardening and is called blue brittleness because it occurs within the blue heat range. If susceptible steels are heated H ithin the 230 IO 370 “C (US to 700 “F) range. they may be embrittled and thus should not be used in pru~s suhjrcted to impact loads.
Tempered
Martensite
Embrittlement
Both inrergranular (Ref I3- IS) and transgranular fracture modes may be observed in tempered martensite embrittlement (Ref 13, 16). The comhination of the segregation of impurities such as phosphorus to the austenitic grain boundaries during austenitizing and the formation of cementite at prior austenitic grain boundaries during tempering are responsible.
Effect of carbon content and tempering temperature on room-temperature hardness of three molybdenum steels. Tempering time: 1 h at temperature
Tempering
There is a loss in impact toughness for steels tempered in the temperature range of 250 to 300 “C (380 to 570 OF). Steels with lower phosphorus content have superior impact properties than steels with a higher phosphorus level. Also. impact toughness decreases with increasing carbon content (Ref 17). Generally, with steels containing either potent carbide forms such as chromium or other impurities that make them susceptible to tempered martensite embrittlement, tempering between 200 to 370 “C (390 to 700 “F) should be avoided.
Hydrogen
Embrittlement
The selection of tempering temperature and the resultant hardness or plasticity must include the consideration of the potential problem of hydrogen embrittlement under these conditions: the part will be exposed to hydrogen through electroplating. phosphating, or other means. or where environmental conditions will cause the cathodic absorption of hydrogen during service. Generally, the restricted notch ductilit) of steels with hardnesses above 10 HRC presents ideal conditions for the development of stress concentrations in parts containing notches or defects that would. in the presence of relatively low hydrogen concentrations. lead to failure at stresses far below the nominal tensile strength of the material. Such parts should be tempered to hardness below 10 HRC if they are to be subjected to relatively high stresses and probable exposure to hydrogen.
References I. C.S. Roberts, B.L. Auerbach. and M. Cohen, The Mechanism and Kinetics of the Fit Stage of Tempering. Trarrs. ASM, Vol35. 1953, p 576-60-I 2. B.S. Lement. B.L. Auerbach. and hf. Cohen, Microstructural Changes on Tempering iron Carbon Alloys, Trarrs. ASM. Vol46. 19%. p 85 l-88 I 3. F.E. Werner. B.L. Auerbach. and M. Cohen, TheTempering of iron Carbon Martensitic Crystals. Trans. ASI%~.Vol-19. 1957. p 823-841
Martempering
tional process.
transformation
(b) Mattempering.
/ 101
4. G.R. Speich. Tempered Ferrous hlartensitic Structures. in Mm/s Huruibook. Vol8,8th ed., American Society for Metals, 1973, p 202-204 5. G.R. Speich and WC. Leslie. Tempering of Steel, Merd. Trms., Vol 3, 197’. p l@l3-1054 6. S. Nagakwra. Y. Hirotsu. hl. Kusunoki. T Suzuki, and Y. Nakarnura, C~stallog~aphic Stud> of the Tempering of hlartensitic Carbon Steel by Electron hlkroscopy and Diffraction. hfe!o/l. Trorrs. A, Vol I4A. 1983, p 1025-1031 7. G. Krauss. Tempering and Structural Change in Ferrous Martensitic Struttures. in Ptme Insrrlrtt,u~nroriorls in Fertms Allop, A.R. Marder and J.I. Goldstein. Ed., TMS-AIhlE. 198-l. p 101-123 8. Modem Sleek cm/ Ttreir Propenies. Handbook 3757.7th ed., Bethlehem Steel Corporation, 1972 9. EC. Bain and H.W. Paston. Altq\ing Ekarrrm in Steel. Anlerican Society for hletds, 1966, p 185, 197 IO. J.H. Holloman and L.D. Jaffe. Tie-Temperature Relations in Tempering Steels, Trans. A/ME, Vol 162. 1945, p 223-249 I I B.J. Schulz. Ph.D. thesis. University of Pennsylvania. 1972 I?. T. lnoue, K. Yamamoto. and S. Seki;ieuchi. Trms. /ml Srrel Insr. Jp., Vol I-l. 1972. p 372 13. J.P. hlaterko~sski and G. Krauss. Tempered hlartensitic Embrittlement in SAE -tNO Steel, hferd. Trczrrs. 4. Vol IOA. 1979. p 1643-1651 I-4. SK. Bane@. C.T. hlcMahon. Jr., and H.C. Feng. lnter~ular Fracture in 4340 Steel Types: Effects of Impurities and Hydrogen, Me&l. Trms. A, Vol9A. 1978. p 737-347 IS. C.L. Briant and S.K. Banerji. Tempered Martensite Embrittlement in Phosphorus Doped Steels. Alrrtrll. Trms. A. Vol I OA, 1979, p l729- I736 16. G. Thomas, Retained Austenite and Tempered Martensite Embrittlement, AlemIl. Trms. .4, Vol 9A, 1978. p 439150 17. F. Zia Ebrahimi and G. Krauss. hlechanisna of Tempered Martensitic Embrittlement in h,ledium Carbon Steels, .4crcl h!eerul/., Vol 32 (No. IO). 198-&p 1767-1777
of Steel
The process entails an interrupted quench from the austenitizing temperature of certain alloy, cast. tool, and stainless steels. Cooling is delq,ed just above martensitic transformation for the lime needed to eyuahze temperature throughout a part, for the purpose of minimizing distortion.
Time-temperature
Processee/Technology
diagrams with superimposed (c) Modified
mat-tempering
cracking. and residual stress. The resulting microsuucture is primarily martcnsitic. and is unvmperrd and brittle. Differences bet\teen conventional quenching and martempering (aka marquenching) are shown in an adjoining Figure (see a and b).
cooling curves showing quenching
and tempering. (a) Conven-
102 / Heat Treater’s
Mechanical
Guide
Properties
of 1095 Steel Heat Treated by Two Methods
Specimen number
Heat treatment
I
Water quench and temper
3 3 4
Water quench and temper Martemper and temper Martemper and temper
Eardoess, ERC
J
Impact enemy ft. Ibf
53.0 52.5 53.0 52.8
16 19 38 33
12 II 28 24
Eloogstion(a),
40
0 0 0 0
(a) In 25 mm or I in.
Marquenching steps: l
l
l
of wrought
steel and cast iron consists of the following
Cooling curves for 1045 steel cylinders quenched in salt, water, and oil. Thermocouples were located at centers of specimens.
Quenching from the austenitizing temperature into a hot fluid medium (oil, molten salt. molten metal, or a fluidized particle bed) at a temperature usually above the martensitic range (M, point) Holding in the quenching medium until the temperature throughout a part is uniform Cooling. usually in air, at a moderate rate to prevent large differences between temperatures on the outside and center of a section
During cooling to room temperature. the formation of martensite throughout a part is fairly uniform. which avoids excessive residual stresses. When the still-hot part is removed from the bath. it is easy to straighten or to form, and will hold its shape on subsequent cooling in a fixture, or in air cooling after removal from a forming die. Following marquenching, parts are tempered in the same manner as conventionally quenched parts. The time lapse between martempering and tempering is not so critical as it is in conventional quenching and tempering operations.
Advantages
of Martempering
Properties of steel treated in conventional water quenching and tempering and steel treated in martempering are compared in an adjoining Table. In martempering residual stresses are lower than those developed in conventional quenching because the greatest thermal variations come while the steel is still in its relatively plastic austenitic condition and because final transformation and thermal changes occur throughout a part at essentially the same time. Other advantages of the process: l l
l
l
l
Susceptibility to cracking is reduced or eliminated When the austenitizing bath is a neutral salt and is controlled by the addition of methane or by proprietary rectifiers to maintain its neutrality. parts are protected with a residual coating of neutral salt until they are immersed in the marquench bath Problems with pollution and tire hazards are greatly reduced if nitratenitrite salts are used. rather than marquenching oils Quenching severity of molten salt is greatly enhanced by agitation and by water additions to the bath Martempering often eliminates the need for quenching fixtures. which are required to minimize distortion in comentional quenching
Modified
Martempering
The only difference between this process and standard martempering is the temperature of the quenching bath-it is below that of the his pointwhich increases the severity of the quench (see c in Figure cited previously). This capability is important for steels with lower hardenabilitj that require faster cooling to get greater depth of hardness. When hot oil is used, the typical martempering temperature in this instance is I75 “C (34.5 “F). By comparison, molten nitrate-nitrite salt baths with water additions and agitation are effective at temperatures as low as I75 “C (345 “F). The molten salt method has some metallurgical and operational advantages.
Martempering
Media
Molten salt and hot oil are widely used. Operating temperature is the most common deciding factor in choosing between salt and oil. For oil, the upper temperature is 205 “C (400 “F). Temperatures up IO 230 “C (445 “F) are an occasional exception. The range for salt is 160 to 400 “C (320 to 750 “F). Composition and Cooling Power of Salt. A commonly used salt contains SO to 60% potassium nitrate, 37 to 50% sodium nitrite, and 0 to IO%, sodium nitrate. This salt’s melting point is approximately I40 “C (285 “F); its working range is I65 to 540 “C (330 to 1000 “F). Salts with a higher melting point (they cost less than the one just described) can be used to get higher operating temperatures. Their composition: 40 to SO8 potassium nitrate. 0 to 30% sodium nitrite, and 20 to 60% sodium nitrate. The cooling power of agitated salt at 205 “C (400 “F) is about the same as that of agitated oil in conventional oil quenching. Water additions increase the cooling power of salt. as indicated by cooling curves in an adjoining Figure and hardness values in a second Figure, in which the cooling power of water is compared with that of water and three types of oil. Salt VS. Oil. Advantages of salt include the following: l l
l
Changes in viscosity are slight over a wide temperature range Salt retains its chermcal stability. Replenishment. usually, is needed only to replace dragout losses Salt is easily washed from work u ith plain water
Disadvantages, l l
salt vs. oil include the following:
Minimum operating temperature of salt is 160 “C (320 “F) Quenching from cyanide-based carburizing salt is hazardous because of possible explosion: explosion and splatter can occur if wet or oily parts
Tempering
Processes/Technology
/ 103
Effects of quenchant and agitation on hardness of 1046 steel
Physical of Steel
Properties
of Two Oils Used for Martempering Value, for oil with operating temperafurebf 95 to ISO~C 150 to 230 T (200 to 300 T)(a) (300 to 45oT)
f%shpoin~(min).“C(“F) Fire pcin~ (min). “C (“F) Vwosity. SUS, at: 38”C(IOO°F) loo”C(210°~ 150”C(300”R 17s”c(3so”F) 20.5 “C (400 OF) 230 “C (-IS0 “I3 Viscosity index (min) Acid number Faq -oil coment C&on residue
Color (a)Temperature
210~110) 2-u f-170) 23S-575 SOS-S I 36.5-37.5
9s 0.00 None 0.05 Optional
175 (525) 310(59S)
Oils For Martempering Properties of two commonly used oils are listed in an adjoining Table. Compounded for the process, they provide higher rates of cooling than conventional oils during the initial stage of quenching. At temperatures between 95 to 230 “C (205 to 445 “F) quenching oil requires special handling. It must be maintained under a protective atmosphere (reducing or neutralj to prolong its life. Exposure to air at elevated temperatures speeds up the deterioration of oil. For every IO “C above 60 “C i I8 above I30 “F) the oxidation rate approximately doubles, causing the formation of sludge and acid, which can affect the hardness and color of workpieces. Oil life can be extended and the production of clean work can be maintained by using bypass or continuous filter units containing suitable tiltering media (clay, cellulose cartridge. or waste cloth). Oils should be circulated at a rate no lower than 0.9 m/s ( I80 ft/min) to break up excessive vapor formed during quenching. Advantages of oil vs. salt include the following:
118-122 5 I-52 -12-13 38-39 35-36 95 0.00 None 0.45
l
Optional
l
range for moctitied martempering
l
Oil can be used at lower temperatures Oil is easier to handle at room temperature Dragout is less
Disadvantages l l
l
of oil vs. salt include the following:
hlaximum operating temperature of oil is 230 “C (445 “F) Oil deteriorates with usage Workpieces require more time to reach temperature equalization Oil, hot or cold, is a fire hazard Soap or emulsifier is needed to wash off oil. Washers must be drained and refilled periodically. Oil wastes present disposal problems
are immersed in high-temperature salt; and there is potential for explosive reactions when atmosphere furnaces are connected to martempering salt quenches and atmospheres are sooty Quenching salt can be contaminated by high-temperature. neutral salt used for heating. To maintain quench severity. sludging is required
l
Niche for Fluidized Beds. Marquenching
Alloy steels generally are more adaptable than carbon steels to martempcring (see Figure). In general. any steel that is normally quenched in oil can be martempered. Some carbon steels that are normally water quenched can be mat-tempered at 205 “C (100 “F) in sections thinner than 5 mm
applications are limited. They have the advantage of equal heat transfer throughout the entire quenching temperature range. The quench rate is reproducible. does not degrade with time, and can be adjusted within wide limits.
l l
Martempering
Applications
104 / Heat Treater’s
Guide
(0.1875 in.), using vigorous agitation of the martempering medium. In addition, thousands of flay cast iron parts are martempered on a routine hasis. The grades of steel that are commonly martempered to full hardness include 1090.3130. ~l3O,-llSO. -1340. 300M (-!3AOhIj. -MO, 5 I-IO. 6150. 8630.86-H~. 8710. 8715. SAE I I-I I, and SAE 52 100. Carburizing Fades such as 33 I2.163O.S 120.8620, and 93 IO also are commonly martempered after carhurizing. Occasionally, higher-alloy steels such as type -l IO stainless are martempered. but this is not a common practice.
Temperature ranges of martensite formation and low-alloy steels
in 14 carbon
Success in martempering is based on a knowledge of the transformation characteristics (TlTcurvesj of the steel being considered. The tempe.rature range in which martensite forms is especially important. Low-carbon and medium-carbon steels 1008 through 1040 are too low in hardenability to be successfully martempered, except when carhurized. The IIT curve for the 1034 steel in an adjoining Figure is characteristic of a steel that is unsuitahle for martempering. Except in sections only a Few thousandths of an inch thick. it would be impossible to quench the steel in hot salt or oil without encountering upper transformation products. Borderline Grades. Some carbon steels higher in manganese content such a< lo-11 and I I-II can be martempered in thin sections. Low-alloy steels that have limited applications for martempering are listed (the lowercarbon grades are carburired before martempering): 1330 to I315.4017- to
Time-temperature transformation diagrams for 1034 and 1090 steels. The 1090 steel was austenitized at 885 “C (1625 “F) and had a grain size of 4 to 5.
Approximate maximum diameters of bars that are hardenable by martempering, oil quenching, and water quenching.
Effects of austenitizing temperature temperature of 52100 steel
on grain size and M,
Tempering Processes/Technology
material being austenitized be uniform. Also, use of a protective atmosphere (or salt) in austenitizing is required because oxide or scale will act as a barrier to unifomr quenching in hot oil or salt. Process variables that must be controlled include austenitizing temperature. temperature of martempering bath, time in mar-tempering bath, salt contamination. \vater additions to salt, agitation, and rate of cooling from the martempering bath. Austenitizing temperature is important because it controls austenitic grain size. degree of homogenization, and carbide solution, and because it affects the M, temperature and increases grain size. (See adjoining Figure.) Temperature control during austenitizing is the same for mar-tempering as for conventional quenching: a tolerance of f8 “C (+I4 “F) is common. The austenitizing temperatures most commonly used for several different steels are indicated in an adjoining Table. In most instances, austenitizinp temperatures for martempering are the same as those for conventional oil quenching. Occasionally, however, medium-carbon steels are austcnitized at higher temperatures prior to martempering to increase as-quenched hardness. Salt Contamination. When parts are carburized or austenitized in a salt bath, they can be directly quenched in an oil bath operating at the martempering temperature. However. if the parts are carburized or austenitized in salt containing cyanide. they must nor be directly mar-tempered in salt because the two types of salts are not compatible and explosions can occur if they are mixed. Instead, one of two procedures should be used: Either air cool from the carburizing bath. wash. reheat to the austenitizing temperature for case and/or core in a chloride bath, and then martemper; or quench from the cyanide-containing bath into a neutral chloride rinse bath maintained at the austenitizing temperature and then martemper. Temperature of the mat-tempering bath varies considerably, depending on composition of workpieces, austenitizing temperature, and desired results. In establishing procedures for new applications. many plants begin at 95 “C (205 “F) for oil quenching, or at about 175 “C (3-15 “F) for salt quenching, and progressively increase the temperature until the best combination of hardness and distortion is obtained. Mar-tempering temperatures (for oil and salt) that represent the experience of several plants are listed in the Tab12 pre\ iously cited.
4032,3118to4137.~22and4~27,1520,5015and50~6,6l1Xand6120. 8115. Most of these alloy steels are suitable for mar-tempering in section thicknesses of up to 16 to 19 mm (0.625 to 0.75 in.). Martempering at temperatures below 205 “C (-100 “F) will improve hardening response, although greater distortion may result than in mar-tempering at higher temperatures. Effect of Mass. The limitation of section thickness or mass must be considered in mar-tempering. With a given severity of quench. there is a limit to bar size beyond which the center of the bar will not cool fast enough to transform entirely IO martensite. This is shown in an adjoining Figure. which compares the maximum diameter of bar that can be hardened by martempering, oil quenching, and water quenching for IO-t.5 steel and five alloy steels in various hardenabilities. For some applications, a fully martensitic structure is unnecessary and a center hardness IO HRC units lower than the maximum obtainable value for a given carbon content may be acceptable. By this criterion, maximum bar diameter is 25 to 300%, greater than the maximum diameter that can be made fully martensitic (see lower graph in Figure just cited). Non-martensitic transformation products (pearlite. ferrite, and bainite) were observed at the positions on end-quenched bars corresponding to this reduced hardness value, as follows: Steel
~ansformation
1045
159, pearlire
8630 1340 52100
IO% ferrite and hainite 20% ferrite and hainite
4150
SOCrpearlitemd btinirr 20% binite
1340
SQ binitc
Control
of Process
Variables
The success of martempering depends on close control of variables throughout the process. It is important that the prior structure of the
Typical Austenitizing
and Martempering Temperatures for Various Steels Austenitizing temperature
Grade
OC
Through-hardening 102-l
/ 105
Mat-tempering
temperature
Oil(a) OF
T
Salt(b) OF
OF
T
steels
I070 II46 1330 4063 4130 -II-to -1140 4340. -1350 52100 52100 8740
Carburizing
steels
3312 1320 4615 1720 8617.8620 8620 9310
(a) Trme in oil varies from 1 to 20 min. depending on section thi&nrss. tb) hlutempttnng range (and sometimes
aho\c range) are used for thinner sections and more intrtcate parts.
temperature
dcpads
on shape and ma>) of part, king
quenched:
higher temperatures
in
106 / Heat Treater’s
Guide
Time in the martempering bath depends on section thickness and on the type, temperature. and degree of agitation of the quenching medium. The effects of section thickness and of temperature and agitation of the quench bath on immersion time are indicated in an adjoining Figure. Because the object of martempering is to develop a martensitic structure with low thermal and transformation stresses, there is no need to hold the steel in the martempering bath for extended periods. Excessive holding lowers foal hardness because it permits transformation to products other than martensite. In addition, stabilization may occur in medium-alloy steels that are held for extended periods al the martempering temperature. The martempering time for temperature equalization in oil is about four fo five times that required in anhydrous salt at the same temperature. Water Additions to Salt. The quenching severity of a nitrate-nitrite salt can be increased significantly by careful addition of water. Agitation of the salt is necessary to disperse the water uniformly, and periodic additions are needed to maintain required water content. The water can be added with complete safety as follows: l
l
l
l
Martempering time versus section size and agitation of quench bath for 1045 steel bars. Effects of bar diameter and agitation of quench bath on time required for centers of 1045 steel bars to reach martempering temperature when quenched from a neutral chloride bath at 845 “C (1555 “F) into anhydrous nitrate-nitrite martempering salt at 205,260, and 315 “C (400,500, and 600 OF). Length of each bar was three times the diameter.
Waler can be misted at a regulated rate into a vigorously agitated area of the molten bath In installations where the salt is pump circulated. returning salt is cascaded into the quench zone. A controlled fine stream of water can be injected into the cascade of returning salt The austemperinp bath can be kept saturated with moisture by introducing steam directly into the bath. The steam line should be trapped and equipped with a discharge Lo avoid emptying condensate directly into the bath Steam addition of water to the bath is done on baths with operating temperatures above 260 “C (500 “F)
Austempering
of Steel
In this process, a ferrous alloy is isothermally quenched at a temperature below that of pearlite formation. Workpieces are heated 10 a temperature within the austenitizing range. usually 790 to 915 “C (l-155 to 1680 “F). Quenching is in a bath maintained at a constant temperature. usually in a range of 260 Lo 400 “C (500 to 750 OF). Parts are allowed to transform isothermally to bainite in this bath. Cooling to room temperature completes the process. The basic differences between austempering and conventional quenching and tempering is shown schemalically in an adjoining Figure. In true austempering. metal must be cooled from the auslenitic temperature to the temperature of the austempering bath fast enough to ensure complete transformation of austenite to bainite.
Compositions austempering
and characteristics
Sodium nitrate. Q Potassium nitrate. % Sodium nitrite, B Melting Point (approx). “C (“F) Working temperature range. “C t0F)
of salts used for
tlibh range
Wide range
G-55 35-5s
O-25 15-55 25-55 150.165(300-330, 17s-540(315-1000,
220 (430) 360-595 (500- I IO0
Treatment of hardenable cast irons is another application. In this case, a unique acicular matrix of bainitic ferrite and stable high-carbon austenite is formed. Advantages of austempering include higher ductility. toughness. and strength at a given hardness (see Table) and reduced distortion. In addition, the overall time cycle is the shortest needed to get through hardness within the range of 35 to 5S HRC.
Quenching
Media
Molten salt is the most commonly used. Formulations and characteristics of two typical baths are given in an adjoining Table. The high range of salt is suitable for only austempering. while the wide range type is suitable for ausrsmpering, martempering, and variations thereof. Quench severities under different conditions are compared in an adjoining Table. The quenching severity of a nitrate-nitrite salt can be boosted significandy with careful additions of water. The salt must be agitated to disperse the water uniformly. Periodic additions are needed to maintain required water contenl. Water usually is added bj directing a stream onto the molten salt at the agitator vortex. A protective water shroud surrounds the water spray Lo prevent spattering. Turbulence of the water carries it into the bath without spattering. a hazard to the operator. Water should never be added from a pail or dipper. Water is continuously evaporating from the bath at a rate H hich increases as hot work is quenched. The amount of waler added to an
Tempering
Comparison of time-temperature
Mechanical
Properties
transformation
HtUdllesS, HRC
Beat treatment
Water quenched and tempered Waler quenched and tempered Martempered and tempered Martempered and tempered Austempered Austempered
I
2 3 4 5 6
open bath varies with the operating temperature the following recommended concentrations: Temperature T
OF
205 260 315 370
400 500 600 700
quenching and tempering and for austempering
J
R Ibf
53.0
16
12
52.5 53.0 S2.8
19 38 33 61 5-t
1-l 28 2-I 4s 40
52.0 52.5
of the salt, as indicated
by
Water concenh-atioo, % ‘4 to 2 ‘/z 10 I ‘I4 10 ‘/2 ‘4
The presence of water can be visually detected by the operator because steam is released when hot work is immersed into the nitrate-nitrite salt. Oil as Quenching Media. Usage is restricted to quenching below 245 “C (475 “F), because of oil’s chemical instability, resulting in changes of viscosity at austempering temperatures.
Quench
severity
comparison
l
II 8
for salt quenches
Still and dry
Agitated and dry A@ated with 0.5% water Agitated with 2% water Agitated with IO%,water 131 Scr “Crossmann number (H)” lb, Requirrs
feasible in treating characteristics.
0.15-0.20 0.25-0.35
0.40-0.50 0.50-0.60
(a)
0.15 0.20-0.2s
0.30-0.40 0.50-0.60(r) Nor possible of Terms Related to Heat
090.I.?lbl In the “Glossar) special enclosed quenching apparatus
5140 and other
steels with
similar
transformation
steels include:
Steels
Selection is based on the transformation characteristics as indicated by time-temperature-transformation (TIT) important considerations are:
l
in., %
Estimated Grossmann number (IQ at temperature 18o~C (36oOF) 370 Yz (7ooOF)
Agitation
Other austempering
l
Elongation In 25 mm, or 1
Impactstrength
Trrating.”
Austempering
/ 107
of 1095 Steel Heat Treated by Three Methods
Specimen
No.
cycles for conventional
Processes/Technology
of a specific steel diagrams. Three
Location of the nose of the IIT curve and the speed of a quench Time needed for complete transformation of austenite to bainite at the austempering temperature Location of the MS point
Because of its transformation characteristics, 1080 carbon steel has limited applicability for austempering (see Figure). Cooling must take place in about I s to avoid the nose of the TIT curve to prevent transformation to pearlite on cooling. Because of this disadvantage, austempering of 1080 is limited to thin sections-the maximum is about 5 mm (0.1 in.). On the other hand, 5 140, a low-alloy steel. is well suited to the process (see TIT curves for 1080.5 140, 1034, and 9261 in an adjoining Figure). About 2 s are allowed to bypass the nose of the curve; transformation to bainite is completed within I to IO tin at 3 I5 to 400 “C (600 to 750 “F). This means that sections thicker than those possible with 1080 steel are
l
l
l
l
Plain carbon steels containing 0.50 to I .OO% carbon and a minimum of 0.604 manganese High-carbon steels containing more than 0.90% carbon and, possibly, a little less than 0.60% manganese Some carbon steels, such as IO-II. with less than O.SO%, carbon and manganese in the range of I .OO to I .6S% Certain low alloys, such as 5 IO0 series alloys, that contain over 0.40% carbon, plus other steels such as -II-u). 6145, and 9440
Some steels sufficient in carbon or alloy content to be hardenable are borderline or impractical because transformation at the nose of the TIT curve sms in less than I s. ruling out the quenching of all but thin sections in molten salt witbout forming some pearlite. or transformation takes excessively long times. Chemical composition is the main determinant of the martensite start (Ms) temperature. Carbon is the most significant variable. Direct effects of other alloying elements are less pronounced, but carbide-forming elements such as molybdenum and vanadium can tie up carbon as alloy carbides and prevent complete solution of carbon.
108 / Heat Treater’s
Time-temperature
Guide
transformation
When applied to wire, the modification
Transformation
diagram for 1080 steel, showing difference between conventional
and modified austempering.
shown is known as patenting.
characteristics of 1080,5140,1034, and 9281 steels, in relation to their suitability for austempering. 1080. limited suitability for austempering because pearlite reaction starts too soon near 540 “C (1000 “F); 5140, well suited to austempering; 1034, impossible to austemper because of extremely fast pearlite reaction time at 540 to 595 “C (1000 to 1105 “F); 9261, not suited to austempering because of slow reaction to bainite at 260 to 400 “C (500 to 750 “F)
Tempering
Hardness
of Various
Steels and Section
Sizes of Austempered
Section size mm
in.
1050 1065 IQ66 108-t
3(b) S(C) 7(C) wi 13(c) S(C)
1086 lo90 1090(e) 10% 1350 4063 -tlSO 436s 5140 5160(e) 8750 so100
20(C) YC) 16(Cl 16(C) 13(C) 25(c)
26(C) 3(b)
8(c)
OF
0.12% b) 0.187(C) 0 281(C)
315 W (d)
655 Id) (d)
0.218(c) 0.516(c) 0.187(c) 0.810(c) 0.118(C) 0.625~) 0.625(c) 0.500(c)
(di W (d) 315(f) Cd) W (d) W (di 345 315(f) 31s (d)
(d) td) (d)
(a~Calculnted. (b) Sheet thickness. (c) Diamelerofsection. (d) Salt temperature condned pearlile as nell as binite. if) Salt with waler addilions. (g) Ehperiment3l
Typical
Production
Applications
hl, temperature(a)
T
I .ooo(c) 0.125(b) I .035(C) 0. IX(b) 0.312(C)
3(b)
T
OF
Badness, HRC
320
610 52s 500 39s 430
-tl-47 53-56 53-56 55-58 ss-58 57-60 443 (a\*@ 57-60 53-56 53-56 52 max 5-l m3.x 4348 46.7 (avg) 1748 57-60
27s 260 200 215
600( f)
adjusted logi~e \nlur
/ 109
Parts
Salt temperature
steel
Processes/Technology
(d) (d) (d) id, (db
21o(gl 235 Z-IS 285 210
410(g) -Iso
6SS 6OOtfj 600 td)
330 2.55 289
630 19Q 51s
maximum
-17s S-IS 110
hardness and 1005, bsinite. (el hlodlfied
austempering:
microsuucr~re
of Austempering
Parts listed in order of increasing section thickness
Part
steel
hlaximum section thiekness mm in.
Parts per unit weight lb kg
Salt temperature OC OF
77Olkg
360 3SS 330 330 370 360 370 360 345 34s 290
Immersion time, mm
6ardlless, ERC
IS IS I5
-I2 -I’ -I8 e-so -I2 J2 1’ 35 -Is-so JS 53 so so
Plain carbon steel parts Clevis Follower arm Spring Plate Cam lever Plae 7)pzbu Tabulator srop Lever Chain link Shoe-last link Shoe-toe cap Lawn mower Made Leter Fastener Stabilizer bar Boron steel bolt
1050 IOSO I080 1060 106.5 1050 106s 106s I050 IOSO 106s 1070 106s 1075 1060 1090 IOB20
0.75 0.7S 0.79 0.81 I .O I .o IO 1.2’ I.25 I.S 1.5 I.5 3.18 3.18
6.35 I9
6.35
0.030 0.030 0.03 I 0.032 0.040 0.041 0.0-w 0.048 0 OS0 0.060 0.060 0.060 0. I IS 0. I25
0.250 0.750 0.250
IlMig 22Okg xx/kg b2kg 0.S kg I4llkg UQlkg
187/lb IQwlh lonb ‘8nb ‘!iIh 6Mb
S72kg 86nig
26011b 39nh xnh ?j I b I l/lb sonb IOlh 4vlb
18/kl. I Sb@ 7alig I I O/kg ‘? kg I-iJ/kg
315 315 385 310
370 -110
680 675 625 b.10
6
7OO
IS IS IS IS IS IS
b75
700 680 650 690 SSO Et 72s F90 700 790
30 60 IS 5 25 6-9 5
b9O 550 620 3nJ
IS 2s -IS I-l
700 700 700 72s 580
30 IS 15 IS
30
s3 18 -to 37 45 30 35-40 15
72s 72s 550-600
5 5 30
30-35(C) 30-39(C) SO(C)
30-3s so -IO--IS 38-43
Alloy steel parts Socket wrench Chain link Pin Cylinder liner Anvil Shovel blade Pin Shaft
6lSO Cr-Ni-V(a) 3140 1140
Gecv Carburized Lever
I :60 I60 ‘5-1
0063
86-10
3.18
4068 3140 111Oibj
3.18
0.063 0.100 0. I25 0.115
6.39 9.53
0.250 0 37s
6150
12.7
o.sQn
0.3 kg I IO/kg s500/kg I5 kg 165kg
‘jib SO/lb 2mYlb 7 lb ‘,, lb
I wkg 0.5 kg -I.-l kg
4vib “, lb 2 Ih
365 290 37s 260 370 370 370 38s 305
33 kg 664
IS lb 30/Ib honb
38S 385 290-3 I5
-IS
steel parts 1010 III7
Shti Block (a1ContainsO.65
8620 to0.7%
C (b) Ladedgrade.
3.06 6.35 II.13
0.1.56 O.lSO 0.438
ICI Case hardness
l3Yhg
110 / Heat Treater’s
Guide
Effect of carbon content in plain carbon steel on the hardness of fine pearlite formed when the quenching curve intersects the nose of the time-temperature diagram for isothermal transformation
pering is a tbo-step process: austenitizing and isothermal transformation in an austempering bath. Generally, applications are limited to parts made from small-diameter bars or from sheet or strip which is small in cross section. The process is especially suitable for the treatment of thin section, carbon steel parts calling for exceptional toughness at hardnesses between 40 and 50 HRC. Reduction in the area of austempered, carbon steel parts usually is much greater than it is for parts conventionally quenched and tempered, as indicated in the following tabulation for 5 mm (0.180 in.) bars of 0.85% carbon, plain carbon steel:
Austempered mechanical properties Tensile strength. MPa (ksi) Keld strength. MPa (ksi) Reduction in area. %, Hardness, HRC
1780(258) 1450(210) 45
SO
Quenched and tempered mechanical properties Tensile strength. MPa (ksi) Yield strength. MI% (hi )
I795 (260) 1550(225) 28
Austenitizing temperature has a significant eFfect on the time at which transformation begins. As this temperature rises above normal (for a given steel) the nose of the TTT curve shifts to the right because of grain coarsening. Use of standard austenitizing temperatures is recommended.
Reduction in area. %, Hardness. HRC
Section Thickness
In commercial austempering practice, acceptable results are obtained with parts having less than 100% bainite. In some instances, 85% bainite is satisfactory. Representative practice in a dozen plants for a variety of parts and steels is summarized in an adjoining Table. Dimensional Control. Dimensional change in austempering usually is less than that experienced in conventional quenching and tempering. The process may be the most effective way to hold close tolerances without excessive straightening or machining after heat treating. Modified Austempering. hlodifications of the process that result in mixed pearlitelbainite structures are quite common in commercial practice. Patenting of wire is an example. Wire or rod is continuously quenched in a bath maintained at 5 IO to 540 “C (950 to 1000 “F) and held forperiods ranging from IO s (for small wire) to 90 s (for rod). Result: Moderately high strength combined uith high ductility. Modified practice varies from true austempering in that the quenching rate is different; instead of being rapid enough to avoid the nose of the TIT tune. it is sufficiently slow to intersect the nose, which results in the formation of tine pearlite. Practice is similar for plain carbon steels at hardnesses between 30 and 12 HRC. In this instance. the hardness of steel quenched at a rate that intersects the nose of the TIT curve varies with carbon content (see Figure).
Limitations
Maximum section thickness is important in determining if a part is a candidate for austempering. The maximum for a 1080 steel, for instance, is about 5 mm (0.2 in.), if the part requires a fully bainitic structure. Steels lower in carbon are restricted to proportionately less thicknesses. However. heavier sections can be handled if a low-carbon steel contains boron. Also, sections thicker than 5 mm (0.2 in.) are regularly austempered in production when some pearlite is tolerated (see Table that lists section thicknesses for specific steels).
Applications Austempering usually is substituted tempering for these reasons: l l l l
To To To To
for conventional
quenching
and
improve mechanical properties reduce the likelihood of cracking and distortion upgrade wear resistance at a given hardness add resistance to subsequent embrittlement
At times. austempering is more economical than conventional quenching and tempering-most likely when small parts are treated in an automated setup in competition with conventional quenching and tempering, which is a three-step operation: austenitizing. quenching, and tempering. Austem-
SO
Carbon Designation
& Alloy
Steels
Introduction
System
Much study and effort have been put into providing a simplified list of steel compositions to serve the metallurgical and engineering requirements of fabricators and users of steel products. These studies have resulted in the carbon and alloy steel compositions listed in Tables 2 to IO and are generally known as the Standard Grades.
Table 1 Types and Approximate Percentages of Identifying Elements in Standard Carbon and Alloy Steels Series designation
AISI-SAE Grades
Carbon
With few exceptions. steel compositions established by the American iron and Steel Institute and the Society of Automotive Engineers (AISI and SAE) use a four-numeral series to designate the standard carbon and alloy steels. specified to chemical composition ranges. In two instances of alloy steels. a five-numeral designation is used. In the alloy steel tables which are presented later in this section. some grades bear the prefix letter E. This denotes that the steel was made by the basic electric furnace process with special practice. In the designations of certain carbon and alloy steels. the suffix letters H and RH signify that the steel is made to comply with specific hardenability limits Carbon or alloy steel designations showmg the letter B inserted between the second and third numerals indicate that the steel contains 0.0005 to 0.003 boron. The letter L inserted between the second and third numerals of the designation indicates that this steel contains 0. IS to 0.35 lead for improved machinability. Table I represents an abbreviated listing of the AISI or SAE carbon and alloy steels. The fust two digits of each series have a detinite meaning, providing the approximate composition of elements other than carbon. The last two digits of the four-numeral designations and the last three digits of the five-numeral designations indicate the approximate mean carbon content of the allowable carbon range. For example. in Grade 1035. the 35 indicates a carbon range of 0.98 to 1.10. These last digits are replaced by XX in Table I. It is ohen necessary to deviate slightl) from this system and to interpolate numbers for some carbon ranges and for variations in manganese. sulfur, or other elements with the same carbon range.
Table 2 Compositions
steels
IOXX IIXX IZXX ISXX Alloy
Description
Nonresulhrize~. RlWlfWiZ~d Rephosphorized Nonresulfurized.
I .oO manganese maximum and resulfurized over I .OO manganese mwmum
steels
13XX 4OXX 4lXX 43xX 46xX 17xx -lxxx 51X.X SIXXX 52xXx 61XX 86XX 87XX 88XX 92xx SOBXX(ab SIBXXw BIBXX(a) 94BXXb)
I .7S manganese 0.20or0.25 molybdenum or0.2S molybdenum and 0.042 sulfur 0.50.0.80.or0.95shronium~d0.I?.0.30.or0.30molyhdenum I .83 nickel. 0.50 to 0.80 chromium. and 0.25 molybdenum 0.85 or I .83 nickel and 0.20 or 0.25 molybdenum I .OS nickel, 0.15 chronuum. 0.20or0.35 molphdenum 3.50 nickel and 0.25 molybdenum 0.80.0.88.0.93.0.9S.or l.oOchromium I 03shromium I .4S chromium 0.60or0.9.5 chromium and 0. I3 or0. IS vanadium minimum 0.55 nickel. O.SOchromium. and 0.20 molybdenum O.SS nickel, O.SOchromium. and 0.25 molybdenum 0.55 nickel, O.SOchromium. and 0 35 molybdenum 2 OOsilicon or I .40 silicon and 0.70 chromium 0.28 or 0.50 chromium 0.80 chromium 0.30 nickel. 0.45 chromium. and 0. I2 molybdenum 0.15 nickel. 0.40 chromium. and 0. I2 molybdenum
(a) B denotes horon steel. Sourw
r\/S/Swe/
Pmducrs Mmrrral
of Standard Carbon H-steels and Standard Carbon Boron H-steels
Steel UNS
designation AISI or SAE Standard
carbon
carbon
ISBZIH, lSB35H. ISB37H ISB-IIH lSB-%H lSB62H
ISBZIRH 15B35RH
C
H 10380 HI0450 H I5220 H 15240 H IS260 HI5110
0.3co.13 0.42-0.5 I 0.17-0.2s 0.18-0.26 0.2 I-O.30 0.35-0.4s
o.so- I .oo o.so- I 00 I .OO- I .SO 1.25-I 7Ya, 1.00-1.50 I .25-l 75(a)
HIS211 HIS351 HI5371 HIS411 HIS381 HIS621
O.I7-0.21 0.31-0.39 0.30-0.39 0.3s-O.-IS 0.43-05.3 0.5-i-0.67
0.70-I .20 O.70- I.20 I .OO- I.50 1.25-1.7S(aJ I .OO- I .50 I.OO-I 50
composition, Pmar
I S max
Si
0.040 0.040 0.040 0.010 0.040 0.040
0.050 0.050 o.oso o.oso 0.050 0.050
0. I s-0.30 0. I s-0.30 0. IS-O.30 0. I s-o.30 0.15.0.30 0. IS-O.30
0.040 0.040 o.@lo 0.040 0.040 0.040
0.050 0.050 0.050 0.050 0.050 o.oso
0. IS-O.30 0. I s-o.30 0. I s-0.30 0. I s-0.30 0. I s-o.30 0.40-0.60
A-steels
l038H IOJSH lS22H lS21H lS26H ISJIH Standard
Cheoucal hIo
No.
boron
(a) Standard AISI-SAE
E-steels
H-steels u ith I .7S manganese maximum
are slassitied
as cxhon
steels
112 / Heat Treater’s Guide Table 3 Compositions of Standard Nonresulfurized Carbon Steels (1 .O Manganese Maximum)
Table 4 Compositions of Standard Nonresulfurized Carbon Steels (Over 1.O Manganese)
Steel designation
Steel
UNS
AISlorSAE
No.
C
GlOO50 G 10060 GlOO80 GIOIOO GlOl20 GIOI30 G10150 GlOl60 GlOl70 Cl0180 GlOl90 GIOXO GlO210 G IO’20 Gl0230 GIO’SO Gl0260 GIO290 Gl0300 G10350 G 10370 G I0380 Gl0390 GIWOO GIO-PO GlO430 GIOUO Gl@iSO Gl0460 GlO490 GIOSOO Gl0530 GIOSSO GlOS90 GlO6OO GlO6-W Cl0650 GlO690 Gl07Oil Gl0750 Gl0780 Gl0800 GlO8-m Gl0850 Cl0860 GlO900 GlO950
0.06 max
0.35 max
0 08 mas
0 25 max
0. IO mu.
0.30-O 50 0.30-0.60 0 30-0.60 0.50-0.80 0.30-0.60 0.60-0.90 0.30-0.60 0 60-O 90 0 70-1.00 0.30-0.60 0.60-0.90 0.70. I .oo 0.30-0.60 0 30-0.60 0 60-O 90 0.60-0.90 0 60-O 90 0 60-0.90 0.70. I Ml 0.60-0.90 0.70. I .OO 0.60-0.90 0 60-0.90 0.70. I .OO 0.30-0.60 0.60-0.90 O.70- I.00 0.60-0.90 0 60-0.90 0.70. I .OO 0.60-0.90 0.50-0.80 0.60-0.90 0.50-0.80 0.60-O 90 0.40-0.70 0.60-O 90 0.40-0.70 0.30-0.60 0 60-O 90 0.60-0.90 0.70-I .OO 0.30-0.50 0.60-O 90 0.30-O so
Ions(ab
lOO6ta, 1008 1010 1012 1013 IO15 IO16 1017 1018 1019 1020 1021 IO22 1023 102s 1026 1029 1030 I035 1037 IO38 IO39 IO-K) IO-11 lo-l3 104-4 lo-15 1046 IO.49 1050 1053 IO.55 1059(a) IO60 106-l 1065 1069 1070 107.5 1078 I080 108-l IO85 1086(a) I090 IO9S
0.08-O. I3 0.10-0.15 0.11-0.16 0.13-O. I8 0.13-0.18 0. I s-0.70 0.150 ‘0 0.15-o ‘0 0.18-0.23 0.18-0.23 0.18-0.23 0.20-0.25 0.22-0.28 0.22-O 28 0 15-0.31 0.28-0.3-I 0.32-0.38 0.32-0.38 0.35-O 12 0 37-0.4-l 0.37-0.4-l 0.10-0.17 o.mo.17 0.13-0.50 0.13-0.50 o.-l3-0.50 0 -16.O.S? o.wo.ss o.-l8-o.ss 0 SO-O.60 0.59-0.65 055-0.65 0.60-0.70 0.60-0.70 0.65-0.75 0.65-O 75 0.70-0.80 0.72-0.85 0.75-0.88 0.80-0.93 0.80-0.93 0.80-0.93 0.85-0.98 0.90. I .03
Chemical composition, “0 Pmav hill 0.040 0.040 0.040 0.040 0.040 0.040 0.040 0.040 0.040 0.040 0.010 0.040 0.040 0.040 0040 0.040 0.040 0.010 0.0-N) 0.010 0.010 0.040 0.040 0.040 0.040 0.040 0.040 O.OXJ 0.040 0.040 0.040 0.040 0.040 0.040 0.040 0.040 0.040 0.040 0.040 0.040 0.040 0.040 0.040 0.040 0.010 0.040 0.040
UNS
AlSlorS.AE
No.
C
hln
0 OS0
IS13 1522 152-l IS26 IS’7 I.541 IS-18 IS51 I5S2 1561
GlSl30 GlS220 G I SXO GlS260 GlS270 GlS4lO G IS180 GISSIO G I.5520 Gl.5610 G IS660
0.10-0.16 0.18.0.24 0.19.0.2S 0.22-0.29 0.22-0.29 0 36-0.U O.-wo.s2 O.-IS-O.56 0.-+7-0.55 0.55-O 65 0.60-0.7 I
l.lO-1.u) 1.10-I.-IO 1.35-1.65 1.10.I.40 I .20- I .so 1.35-1.65 l.lO-I.40 0851.15 1.20-1.50 0.75-1.05 OX?-I.15
0.050 o.oso 0.050 0.050 0 050 0.050 0.050 0.050 0.050 0.050 0.050 0.050 0.050 0.040 0.050 0.050 0.050 0.050 0.050 O.OSO 0.050 0.050 0.050 0.050 0.050 0 050 0.050 0.050 0.050 0.050 0 OS0 0.050 0.050 0 OS0 o.oso 0.050 0.050 0.050 0.050 0.050 0.050 0.050 0.050 0.050 0.050 0.050
(a) Standard steel grades for w ire rods and u ire only
Detailed composition ranges will be pro\tded senes in other tables which follow.
Unified Numbering
Chemical composition, %
designation S max
for each member of each
System
The standard carbon and alloy grades established by AISI or SAE have now been assigned designations in the Unified Numbering System (UNS) by the American Society for Testing and hlaterials (ASTM ES27) and the Society of Automotive Engineers (SAE Jl868). In the composition tables which follow. the CJNS numbers are listed along with their corresponding AISI-SAE numbers. The UNS number consists of a single letter prefix followed by Eve numerals. The prefix letter G indicates standard grades of carbon or alloy steels. while the pretix letters H and RH indicate standard grades which meet certain hardenability limits. The first four digits of the UNS designa-
Pmax
S may
004 0.040 0.040 0.040 0.040 0.040 0.040 0.040 0.040 0.040 0.040
0.050 o.oso 0.0.50 o.oso 0.050 0.050 0.050 0.050 0.050 0.050 0.050
tions usually correspond to the standard AISI-SAE designations, while the last digit (other than zero) denotes some additional composition requirement such as lead or boron. The digit is sometimes a 6. which is used to designate steels which are made by the basic electric furnace with special practices. The tern1 carbon steel does not necessarily mean that the steel does not contain any other alloying elements. There are, however. sharp restrictions on the amounts of alloy that may be contained in carbon steels. These generally agreed upon restrictions are summarized in the paragraphs which follow. Steel is considered to be a carbon steel when no minimum content is specified or required for aluminum (except as related to deoxidization or gram size control). chromium. cobalt. columbium (niobium). molybdenum, nickel. tmum.m~. tungsten. vanadium. ztrconium. or any other element added to obtarn a desired alloymg effect. Further restrictions include: (a) when the specified minimum for copper does not exceed O.-IO or(b) when the maximum content specified for any of the following elements does not exceed the percentages noted: I .6S manganese. 0.60 silicon, 0.60 copper. Boron may be added to carbon steels to improve hardenability (see Table 2). In all carbon steels. small quantities of alloying elements or residuals. such as nickel. chromium. and molybdenum. are present. Their existence is unavoidable because they are retained from the raw materials used for melting. As a rule, small amounts of these elements have little or no meaning to the fabricator. For purposes of identity and because of the wide variations in properties. compositions of the standard carbon steels are presented in five separate tables.
Standard
Nonresulfurized
Grades
Compositions for -t8 standard nonresulfurized grades. I.0 manganese maximum. are given in Table 3. hlany of these grades are available with an addition of 0. IS to 0.35 lead to improve machinability. When lead is added. it is denoted by the letter L between the second and third digtts. For example. a leaded grade of 1035 IS denoted as I0L-G. Similarly. many of these grades ‘are available with a boron addition. A letter B IS mserted between the second and thud digits, such as lOB35. Compositions for I I additional standard carbon steels are presented in Table -1. The essential difference between the steels listed in Table 3, assuming the same carbon content. and those listed in Table 4 is the higher manganese content of the latter group. For one grade, it is as high as I .6S. which is the borderline between carbon steels and alloy steel. Higher manganese increases hardenability. The grades listed in Table -I may also be produced with additions of lead or boron as described above for the grades listed in Table 3.
Standard
Resulfurized
Carbon Steels
Compositions listed in Table 5 represent those grades of standard carbon steels which ha\e been resulfurizcd. as high as 0.33 sulfur, for improved
Carbon
Table 5
Compositions
of Standard
Resulfurized
Note data point, 0
SICA designation AlSl or SAE
UNS No.
C
GI 1080 GIIIOO Glll30 Glll70 Glll80 Gll370 Gll390 GII-IOO GIlllO GIIUO Gll460 GIISIO
0.08-o. I3 0.08-O. I3 0. I3 “,M 0.11-0.20 0.11-0.20 0.32-0.39 0.35-0.43 0.37-0.44 0.37-0.1s 0.40-0.48 0.12-0.49 0.18-0.55
Chemical hlo
composition, Pmax
0.50-0.80 0.30-0.60 0.70-I .OO I .OO- I .30 1.30-1.60 I .35- I .6S I .35- I .65 0.70-I 00 1.35-1.6.5 1.35-1.65 0.70. I on 0.70. I .OO
Table 6 Compositions of Standard and Resulfurized Carbon Steels Steel designation AISI or SAE I211 I212 1213 1215 12LI-1
/ 113
Fig. 1 Relationship Between Carbon Content and Maximum Hardness. Full hardness can be obtained with as little as 0.60 C.
Carbon Steels
1108 1110 1113 1117 1118 1137 1139 II-IO 1141 114-l 1146 1151
& Alloy Steels Introduction
UNS No. Gl2llO GI2120 Gl2130 Gl2lSO GI2I.U
Chemical lull
C 0.13max 0.13max 0.13miu 009mrul O.lSmax
0.60-0.90 0.70-1.00 0.70-1.00 0.75-1.05 0.85-1.15
Standard Rephosphorized Carbon Steels
s
0.040 0.040 0.07-O. I2 0.040 0.040 0.040 0.040 0.040 0.040 0.040 0.010 0.040
0.08-O. I3 0.08-O. I3 0.24-0.33 0.08-O. I3 0.08-O. I3 0.08-O. I3 O.I3-0.20 0.08-O. I3 0.08-O. I3 0.2-t-0.33 0.08-o. I3 0.08-O. I3
Fig. 2 Relationship Between Carbon Content and Maximum Hardness. Usually attained in commercial hardening
Rephosphorized
composition, P 0.07-0.12 0.07-012 0.07-0.12 0.04-0.09 0.0-l-0.09
These grades are also available funher improvement in machinability.
machinability.
8
% S
&IO-0.15 0.16-0.23 0.2-bO.33 0.26-0.35 0.26-0.35
Pb .__
0.15-0.35,
afith lead additions
for
and Resulfurized
Table 6 lists compositions for four grades ofcarbon steels which contain higher than normal amounts of phosphorus as Nell as sulfur. One grade. IZLI-1. has been rephosphorized. resulikized. and leaded. All of the above conditions and additions contribute to the superior machining characteristics of these grades. Any steel from this group ma! be produced H ith additions of 0. I5 to 0.35 lead.
Alloy Steels A steel is considered to be an alloy grade u hen the maximum of the range given for the content of alloying elements exceeds one or more of the following limits: (a) I .6S manganese. (b) 0.60 silicon. (c) 0.60 copper. It is also considered an alloy steel uhen a definite minimum quantity of any of the following elements is specified or requued mfithin the limits of the recognized constructional alloy steels: (a) aluminum. (b) chromium. (c) cobalt. (d) columbium (niobium). (e) molybdenum.(f) nickel. (g) titanium, (h) tungsten. (f) vanadium. (b) zirconium. or any other alloying element added to obtain a specific alloying effect. As a rule. the total amount of alloy in these AISI-SAE Standard Grades of Alloy Steels does not exceed approximately 4.0 over and abobe that amount normally permitted in carbon steels. Compositions of Standard Alloy Steels. Compositions for a total of 58 different alloy steels are listed in Table 7. It might seem that there is great similarity among grades in some instances and that the liht could easily be reduced in number of grades. Houe\er. many different cornpow tions are required to fulfill the thousands of mechanical and physical propeny requirements for manufactured products. The demands of fabricability and economy are also factors which must be satisfied. often with ver> precise chemical compositions.
While the various compositions listed in Table 7 are not produced in equal quantities. each of the steels listed in this table is produced in significant quantities by numerous mills. A large number of them are also available through steel service centers. Almost all of the 58 compositions listed in Table 7 are available with lead additions for improved machinabiliry. and some manufacmrers produce certain alloy grades as resulfunzed steels. also to induce better machinabilit). Compositions of Standard Boron Steels. Compositions of the standard alloq grades which contain 0.0005 to 0.003 boron are listed in Table 8. The boron pro\ ides an increase in hardenability for these steels which are relativeI> lean alloys.
Hardenability Hardenabilitj and methods for increasmg this property. such as boron additions. are referred to several times uithin this article. However. hardenability does not necessarily mean the ability to be hardened to a certain Rockwell or Brine11 value. For example. Just because a given steel is capable of beI” hardened to 65 HRC does not necessarily mean that it has high hardennblhtj. Also. a steel that can be hardened to only 40 HRC may have very high hardenability. Hardenability refers to capacity of hardening tdeprh) rather than to mn\imum attainable hardness.
Role of Carbon The carbon content of a steel deremtines the maximum hardness attainable. urith particular emphasis on rhe word attainable. The effect of carbon on attainable hardness is demonstrated in Fig. I The maximum attainable hardness requires onlj about 0.60 carbon. Houever. the data shohn in Fig. I are actually theoretical. because the) are based upon heat treating of wafer-thin sections which are cooled from their austenitizing temperature to room temperature within a matter of seconds. thus developing 100%
114 / Heat Treater’s Guide martensite throughout their sections. Therefore, the ideal condition shown in Fig. I is seldom attained in practice. Figure 2 shows a better example of hardness versus carbon content because it is a more accurate condition, one expected in commercial practice. The most important factor influencing the maximum hardness that can be attained is mass of the metal being quenched. In a small section, the heat is extracted quickly, thus exceeding the critical cooling rate of the specific
Table 7 Compositions Steel designation AISI or SAE 1330 I335 1340 I345 4023 4002-l 4027 4028 4037 4047 4118 4130 4137 1140 1142 4115 1117 3150 4161 4320 43-m E1340 4615 4620 4626 3720 1815 4817 1820 5117 5120 5130 5132 5135 5140 5150 51s 5160 E5llOO E52lOO 6118 6150 8615 8617 8620 8622 8625 8627 8630 8637 8640 8641 8645 8655 8720 8740 8822 9260
steel. The critical cooling rate is that rate of cooling which must be exceeded to prevent formation of nonmartensitic products. As section size increases. it becomes increasingly difficult to extract the heat fast enough to exceed the critical cooling rate and thus avoid formation of nonmartensitic products. A typical condition is shown in Fig. 3, which illustrates the effect of section size on surface hardness and is a good example of the mass effect. For small sections up to I3 mm (0.5 in.), full hardness of approxi-
of Standard Alloy Steels
IJNS No.
C
hill
Pmax
Gl3300 Gl3350 G13400 Gl31SO G-40230 G-IO240 GUI270 G-l0380 G-l0370 G-IO-170 G-Ill80 G113OO G4 I370 GII-KlO G-l1420 G11150 G-II 470 G-l1500 G-l1610 GA3200 G-t3400 G-i3406 G-16150 G-t6200 G-l.6260 G17’OO G-R? I50 G38 I70 G-18200 GSll70 GSl200 GSl300 G5 I320 G5 I350 GSI400 G51500 G5lSSO GSl600 GSl986 GS2986 G6l I80 G615OO G86 I so G86170 G86200 G86220 G86250 G86270 G86300 G86370 G86400 G86120 G864SO G86SSO G87200 G87UKl G88220 G92600
0.28-0.33 0.33-0.38 0.38-0.13 0.43-0.48 0.20-0.2s 0.20-0.25 0.25-0.30 0.25-0.30 0.35-0.40 O.-e-0.50 0.18-0.23 0.28-0.33 0.35-0.40 0.38-0.43 0.40-0.4s 0.13-0.48 0.45-0.50 0.18-0.53 0.56-0.6-l 0.17-0.22 0.38-0.13 0.38-0.13 0.13-0.18 O.I7-0.22 0.2-1-0.29 0.17-o 22 0.13-O. I8 0. I S-O.20 0.18-0.23 0.15-020 0.17-0.22 0.28-0.33 0.30-0.3s 0.33-0.38 0.38-0.13 0 48-0.53 0.5 I-O.59 0.56-0.64 0.98-1.10 0.98. I. IO 0.16-0.2 I 0.18-0.53 0.13-0.18 0.15-0.20 0.18-0.23 0.20-0.25 0.23-0.28 0.25-0.30 0.28-0.33 0.35-0.40 0.38-0.43 0.40-0.45 0.13-0.48 0.5 I-O.59 0.18-0.23 0.38-0.13 0.20-0.2s 0.56-0.64
I .60- I .90 1.60-1.90 I .60-I .90 1.60-1.90 0.70-0.90 0.70-0.90 0.70-0.90 0.70-0.90 0.70-0.90 0.70-0.90 0.70-0.90 O.-iO-0.60 0 70-0.90 0.7s I .OO 0.7s I 00 0.75-I 00 0.75-1.00 0.7s-I 00 0.75. I.00 0.15465 0.60-0.80 0.65-0.85 0.15-0.65 0.15-0.65 0.45-0.65 0.50-0.70 0.10-0.60 0.10-0.60 0.50-0.70 0.70-0.90 0.70-0.90 0.70-0.90 0.60-0.80 0.60-0.80 0.70-0.90 0.70-0.90 0.70-0.90 0.75-1.00 0.25.0.15 0.3-0.45 0.50-0.70 0.70-0.90 0.70-O 90 0.70-0.90 0.70-0.90 0.70-0.90 0.70-0.90 0.70-0.90 0.70-0.90 0.75 I 00 0.7% I .OO 0.75-I .Oo 0.7sI Ml 0.75 I.00 0.70-0.90 0.7.5. I .oo 0.75 I .OO 0.75-l 00
0.03s 0.035 0.035 0.035 0.035 0.035 0.035 0.035 0.035 0.035 0.035 0.03s 0.035 0.035 0.035 0.035 0.035 0.035 0.035 0.035 0.039 0.02s 0.035 0.03s 0.035 0.03s 0.035 0.035 0.035 0.035 0.03s 0.035 0035 0.035 0.035 0.035 0 035 0.035 0.025 0.025 0.035 0.035 0.035 0.035 0.035 0.035 0.035 0.03s 0.035 0.035 0.035 0.035 0.035 0.035 0.035 0.035 0.035 0.035
Chemical S max
composition,
0.040 0.040 0.040 O.UlO 0.040 0.035-0.050 0.040 0.035-O OS0 0.040 0.040 0.040 0.040 O.O-lO o.o-lo O.O-lO 0.040 0.040 0.040 0.040 0040 0.040 0 01s 0.040 0.040 0040 0.UK.l 0.040 0040 0Q-W O.O-lO O.UUl 0.040 0.040 0.040 0.040 0.040 0.040 0.040 0.03 0.03 0.040 0.040 0.040 OUUI 0.040 0040 0.040 0.040 0.040 0.040 0040 0.040 OUUI 0.O-U.l O.WO 0.040 0040 0.040
% Si
0. IS-O.30 0.15-0.30 0.15-0.30 0. IS-O.30 0. I S-0.30 0. I s-o.30 0.15-0.30 0. I SO.30 0. I s-o.30 0. I s-o.30 0. I S-O.30 0. I S-0.30 0.15-0.30 0.15-o 30 0.15-o 30 O.I5-0.30 0. I S-0.30 0.15-0.30 0. I S-0.30 0.15-0.30 0.15-0.30 0.15.0.30 0. IS-O.30 0. I s-o.30 0.15-0.30 0.15-0.30 0. I S-O.30 0. I s-o.30 0. IS-O.30 0. I s-0.30 0 IS-O.30 0. I s-0.30 0.15-O 30 0 IS-O.30 0 IS-O.30 0.15-o 30 0.15-0.30 0. IS-O.30 0. I s-0.30 0. I S-O.30 0.15-0.30 0. I s-o.30 0.15-0.30 0. I s-0.30 0. I s-o.30 0.15-0.30 0. I s-o.30 0.15.0.30 0.15-0.30 0.15-0.30 0. IS -0.30 0.15-0.30 0. I s-o.30 0. I s-o.30 0. I s-o.30 0 I s-0.30 0.15-0.30 I 80-2.20
Ni
Cr
0.40-0.60
I .hS-2.Ou I .6S-2.00 I .65-2.00 I .65-2.00 I .65-2.00 070-,100 0.9U I .20 3.35-3.7s 3.25-3.7s 3.25-3.7s
0.40-0.70 0.40-0.70 0 40-0.70 0.40-0.70 0.10-0.70 0.40-0.70 0.40-0.70 0.10-0.70 0.4UO.70 0.4UO.70 0.40-0.70 0.40-0.70 0 30-0.70 0.10-0 70 0.10-0.70
0.8Ul.10 0.8Ul.10 0.8Ul.10 0.80- I. IO 0.8Ul.10 0.80-1.10 0.8Ul.10 0.7uo.90 0.40-0.60 0.7uo.90 0.7uo.90
0.35-0.55
0.7uo.90 0.7uo.90 0.80-1.10 0.7s- I 00 0.8U I .05 0.70-0.90 0.70-0.90 0.7uo.90 0.7uo.90 0.90-1.1s I .3u I.60 o.suo.7o 0.80. I. IO O.JUO.60 0.10-0.60 0.40-0.60 0.40-0.60 0.40-0.60 0.40-0.60 0.40-0.60 0.10-0.60 0.40-0.60 0.40-0.60 0 40-0.60 0.40-0.60 O.NLO.60 O.-K-O.60 0.40-0.60
MO
0.20-0.30 0.20-0.30 0.20-0.30 0.20-0.30 0.20-0.30 0.20-0.30 0.08-o. I5 0. IS-O.25 0. IS-O.25 0. IS-O.25 0. I s-o.25 0. IS-O.25 0. I s-o.25 0. I s-o.25 0.25-0.35 0.2UO.30 0.20-0.30 0.2uo.30 0.20-0.30 0.20-0.30 0. I s-0.25 0.15-0.25 0.20-0.30 0.20-0.30 0.2uo.30
0.10-0.15 v O.lSVmin 0. IS-O.25 0.15-0.2s 0. I s-o.25 0.1%0.25 0.15.0.25 0. I s-o.25 0. I s-o.25 0. I s-o.25 0. I s-o.25 0. I5-0.25 0. I SO.25 0. I so.25 0.20-0.30 0.20-0.30 0.3uo.40
Carbon & Alloy Steels Introduction Table 8 Compositions Steel designation AISI or SAE 508-u 50B-l.6 SOB50 SOB60 SIB60 8lBxi 94817 93830
Steel designation AISI or SAE I330H I335H l34OH I .34SH 33lORH 4027H 4027RH m28H 4032H 3037H 4042H 4047H 4118H -lllOH 4I2ORl-l -ll30H 413SH Jl37H 414OH 1112H 4l4SH ll45RH ll47H 4150H 416lH 116lRH 1320H J32ORH 434OH U34OH WOH 4626H 4720H 18lSH 4817H 4820H 4820RH SW6H 5120H 5130H 513oRH Sl32H 5135H 514OH SI-IORH SISOH SISSH 516OH 516ORH 6ll8H
of Standard Boron (Alloy) Steels
UNS No.
C
GSOUI G504.61 GSOSO I GSXOI GSl601 G81351 G9-1171 G9330 I
0.43-0.48 0.44-0.19 0.48-0.53 0.56-0.6-I 0.56-0.6-l 0.43-0.48 0. I s-o.20 0.28-0.33
Table 9 Compositions UNS No. HI3300 H I33SO HI3400 H I3150 H40270 H-U)280 HA0320 HA0370 H40420 H40470 H-II I80 H41200 H-i1300 H41350 H1 I370 HJl400 HJI-120 HJl-450 HA1470 H1lSOO H41610 H33200 H-t3400 H-13406 H-i6200 H-W60 H-17200 H48150 H48170 H-i8200 H50460 HSl200 HSl300 H51320 HSl350 HSl400 HSISOO HS I550 H51600 H61180
/ 115
MO 0.75. 0.7s 0.7s0.75 0.7s0.7s 0.75-I 0.7s
I .OO I .Ocl I .OO I .OO I .OO I Ml .OO I .OO
Pmax
Chemical Smax
0.035 0.035 0.035 0.035 0.03s 0.035 0.035 0.035
0.040 0.040 0.040 0.040 0040 0.040 0.040 0040
composition,
% Si
0.15-0.30 0.15-0.30 0. I s-0.30 0. IS-O.30 0.15-0.30 0. IS-O.30 0. IS-O.30 0. I s-o.30
Ni
Cr
MO
0.20-0.40 0.30-0.60 O.30-0.60
0.40-0.60 0.20-0.35 0.40-O 60 0.40-0.60 0.70-0.90 0.3s-0.55 0.30-0.50 0.30-0.50
0.08-O. IS 0.08-O. IS 0.08-O. I5
Ni
Cr
hlo
of Standard Alloy H- and RH-Steels
C 0.27-O 33 0.32-0.38 0.37-0.4-l o.-lz-0 49 0.08-O. I3 0 240.30 0.2s-0.30 0.24-0.30 0.29-0.35 0.3-I-0.1 I 0.39-0.16 O.-w0.5 I 0.17-0.23 0 18-0.23 0.18-0.23 0.27-0.33 0 32-0.38 0.31-0.1 I 0.37-0.4-l 0.39-0.16 0.12-0.49 0.43-0.48 0.44-0.5 I 0.47.05-l 0.55-0.65 0.56-0.6-l 0.17-0.23 O.I7-0.22 0.37-0.-u 0.37.0.u 0.17-0.23 0.23-0.29 0.17-0.23 0.12-0.18 0.13-0.20 0.17-0.23 0.18-0.23 0.13.o.so 0.17-0.23 0.27-0.33 0.28-0.33 0.29-0.3s 0.32-0.38 0.37-0.44 0.38-0.33 0.47-0.54 O.SO-0.60 0.55-0.65 0.56-0.63 0.15-0.21
hln I .-Is-1.05 I .-Is-2.05 I .J5-2.05 1.35-2.05 0.10-0.60 0.60- I.00 0.70-0.90 0.60. I.00 0.60- I.00 0.60-I .OO 0.60. I .OO 0.60-I .OO 0.60. I .OO 0.90-I .2O 0.90. I.20 0.30-0.70 0.60- I.00 0.60. I.00 0.65-1.10 0.65-1.10 0.65-1.10 0.75-1.0 0.65-1.10 0.65-1.10 065-1.10 0.75 I .o 0.40-0.70 0.45-0.65 0.55-0.90 0.60-0.95 0.35-0.7s 0.40-0.70 O.-IS-0.75 0 30-0.70 0.30-0.70 0.40-0.80 O.SO-0.70 0.65-1.10 0.60- I .OO 0.60-I .OO 0.70-0.90 0.50-0.90 0.50-0.90 0.60- I .OO 0.70-0.90 0.60- I .OO 0.60. I .OO 0.65- I .OO 0.75 I.00 0.40-0.80
Pmax
Chemical Smav
composition,
B Si
0 15-0.30 0 15-0.30 0.15-0.30 0 15-0.30 0.15-0.35 0. IS-O.30 0. IS-O.35 0. IS-O.30 0. I S-0.30 0. IS-O.30 0. IS-O.30 0. IS-O.30 0. I s-o.30 0. I s-o 35 0. I s-0.35 0.1s.0 30 0. I j-O.30 0. IS-O.30 0. I s-o.30 0. I s-0.30 0. I s-o.30 O.ls:b.30 0.15-0.30 0. I s-o.30 0.15-0.35 0. IS-O.30 0 15-0.3s 0. IS-O.30 0.15.0.30 0.15-0.30 0. IS-O.30 0 15-0.30 0. I s-o.30 0. IS-O.30 0.15-0.30 0 15-o 35 O.lS-0.30 0 15-0.30 0.15-0.30 0. I s-o.35 O.IS-0.30 0. IS-O.30 0. I s-0.30 11.IS-O.35 0. IS-O.30 0. I s-0.30 0. IS-O.30 0. I s-o.35 0. I s-o.30
3.2S-3.7.5
I .SS-2.00 I .6S-2.00 I .ss-2.00 I .ss-2.00 I .SS-2.00 0.65. I .05 0.85 I.25 3.20-3.80 3.20-3.80 3.20-3.80 3.25-3.7s
I.-u-I.75
0.30-0.70 0.40-0.60 0.40-0.60 0.75-l .?O 0.75-1.20 0.75- I.20 0.75-1.20 0.75-1.20 0.7sI.20 0.80-1.10 0.75 I.20 0.75-1.20 0.65-0.95 0.70-0.90 0.35-0.65 0.10-0.60 0.65.0.9s 0.65-0.95
0.30-0.60
O.I3-0.43 0.60-I .OO 0.75-l .20 0.80-l IO 0.65-1.10 0.70-1.15 0.60-I .cKl 0.70-0.90 0.60- I .cKl 0.60-I .Oo of3 I .oo 0.70-0.90 0.U0.80
0.20-0.30 0.20-0.30 0.20-0.30 0.20-0.30 0.20-0.30 0.20-0.30 0.20-0.30 0.08-o. IS 0.13-0.20 0.13-0.20 0. I s-o.15 0. I so.25 0. I so.25 0. I s-o.25 0. I WI.25 0. I s-o.25 0. I S-O.25 0. I s-o.25 0.15-0.2.5 0.25-0.3s 0.25-0.3s 0.20-0.30 0.20-0.30 0.20-0.30 0.20-0.30 0.20-0.30 0. I s-o.25 0. I so.25 0.20-0.30 0.20-0.30 0.204.30 0.20-0.30
0.10-0.15
118 / Heat Treater’s Guide Table 9 Compositions Steel designation AISI or SAE 6150H 8617H 8620H 8622H 8611RH 862SH 8617H 863OH 8637H 564OH 8642H 864SH 8650H 8655H 866OH 871OH 8720RH 874lH XKEH 8811RH YXOH 9310H 93 IORH
of Standard Alloy H- and RH-Steels (continued)
1rNs No.
C
bin
Pmax
Chemical S mar
H6lSOO H86 I70 H862OO H86220
0.17-0.51 0. I-LO.20 0.17-0’3 0. I9-0.25 0.20-0.2s 0.22-0.28 0.21-0.30 0 ‘7-0.33 0 3-l-0.41 0.37-0.4-l 0.39-0.46 0.42-0.19 0.47-0.51 0.50-0.60 0.55-0.65 O.I7-0.23 0.18-0.73 0.37-0.4-l O.I9-0.25 0.20-O 25 O.SS-0.65 0.07-O 13 0.084. I3
0.60-l 00 0.60-0.95 0.60-0.95 0.60-0.95 0.70-0.90 0.60-O 9.5 0.60-O 95 0.60-0.95 0.70-I OS 0.70. I .OS 0.70-I .os 0.70-I OS 0.70. I 05 0.70. I 05 0.70. I .os 0.60-0.95 0.70-0.90 0.70-I .os 0.70-I .Oj 0.7% I .OO 0.65.I.10 0.10-0.70 0.45-0.65
0.03S 0.035 0.03s 0.035
0.040 0.040 0.040 0.040
0.035 0.035 0.035 0.035 0.035 0.035 0.035 0.035 0.035 0.035 0.035
0.040 0.040 0.040 0.040 0040 0.040 0.040 0.040 0040 0.040 0040
H862SO H86270 H86300 H86370 H86400 H86-420 H86-150 H86SOn H865SO H866OO H87200 H874OO H88220 H926OO H93100
Table 10 Compositions Steel designation Al!31 or SAE
0025 0 035
00-m 0.040
0035 0.035
O.&J 0.040
Z Si
Ni
0.1s0.30 0.15-O 30 0. I S-0.30 0. I s-o.30 0. I S-0.35 0. I s-o 30 0. IS -0.30 0. I S-O.30 0. I5-0.30 0. I s-o.30 0.15-030 0.15-0.30 0.15-0.30 0.15-0.30 0.15-0.30 0.15-0.30 0. IS-O.35 0 IS-O 30 0. I j-O.30 0.1s0.35 I .70-z 20 0.1%0.30 0. I s-o 35
0.35-0.75 0.3.5-0.7s 0.35-0.7s 0.10-0.70 0.35-0.7s 0.35-0.75 0.35-0.7s 0.35-0.75 0.35.0.7.i 0.35-0.7S 0.35-0.75 0.35-O 75 0.35-0.75 0.35-0.75 0.35-0.7s 0.10-0.70 0.35-0.7s 0.35-0.7s 0.40-0.70 2.95-3 55 3.00-3.50
Cr
MO
0.75 I.20 0.35-0.65 0.35-0.65 0.35-0.65
O.lSVmin 0. IS-O.25 0. I S-O.25 0. IS-O.25 0.15-0.25 0. I s-o.25 0.15-0.25 0.15-0.2s 0. I S-O.65 0. IS-O.25 0. IS-o.29 0.15-0.25 0. I5-0.25 0.15-0.25 0.15-0.25
0.40-0.60 0.35-0.65 0.35-0.65 0.35-0.6.5 0.3.5-0.6.5 0.35-0.65 0.35-0.65 0.35-0.65 0.35-0.65 0.35-0.65 0.35-0.65
0.35-0.65 0.40-0.60 0.3S-0.65 0.35-0.65 0.10-0.60
0.20-0.30 0.2uo.30 0.20-0.30 0.3uo.-lo 0.3uo.40
I .OO- I .45 I .OO- I .-IO
0.08-O. IS 0.08-o. IS
of Standard Boron (Alloy) H- and RH-Steels
UNS No.
Chemical S max
c
hln
Pmax
0.65-1.10 0.75. I On 0.65I.10
0.03s
0.040
0.035 0.035
0040 0 040 0.040 0.040 0.040 0.040 0.040 0.040 0.040 0.040 0.040
SOB-NIH
HSOJOI
WB-IORH SOBUH 50B16H SOBSOH SOB60H 5 I BhOH 81 B1SH 86830H 86815H 9-IBlSH 91B17H Y-IB30H
0.37-0.u 0.38.O.-l3
HSOUI HSO-161 HS050 ! HS060 I H516Ol H81151 H863111 H8615 I H93151 H91171 H9-l-1301
0.42-O 19 0.43.O.SO 0.-!7-051
055-0.65 055-0.65 0.42-0.49 0.27-0.33
O.-EO.-l9 0.12-O I8 0. I-I-O 20 0.27-0.33
0.65-1.10 0.65-1.10 0.65-l IO 0.65-1.10 0.70. I .os 0.60.0.9s 0.70. I .os 0.70-I .os 0.70-I .os 0.70. I .os
0.035 0.035
0.03s 0.035 0.035 0.035
0.035 0.03.i 0035
mately 63 HRC is attainable. As the diameter of the quenched piece is increased. cooling rates and hardness decrease. because the critical cooling rate for this specific steel was not exceeded. Thus. Fig. 3 also serves as an escellent example of a low-hardcnabilitj steel. Plain carbon steels are characterized by their low hardenability, with critical cooling rates lasting only for brief periods. Hardcnability of all steels is directly related to critical cooling rates. The longer the time of critical cooling rate. the higher the hardenability for a given steel. almost regardless of carbon content.
Role of Alloying
composition,
Elements
The principal reason for using alloying elements In the standard grades of steel is IO increase hardenabilitj. The alloying elements used in the standard alloy steels in Table 7 are confined to:(a) manganese. (b) silicon. (cl chromium. cd) nickel, (e) mol) bdenum. and (f) vanadium. Because of the small amounts used, boron is not usually called an alloy. Steels that contain boron. whether they are carbon or alloy grades. are more often termed as boron-treated steels. The use of cobalt. tunps’en. zirconium. and
composition,
% Si
0. I s-o.30 0 IS-O.35 0 IS-O 30 0 15-o 30 0. I S-O.30 0. I s-o. 30 0.15-0.30 0.15-0.30 0. I s-o.30 0.15-O 30 0.15.0.30 0.15-0.30 0. I s-0.30
Ni
0. I S-O.45 O..lS-0.75 0.35-0.7s 0.25-O 6S 0.50 65 0.25-0.6S
Cr 0.3uo.70 0.40-0.60 0.30-0.70 0.13-0.13 0.30-0.70 0.30-0.70 0.60-I MI 0.30-0.60 0.35-0.65 0.35-0.65 0.25-0.55
0.25-0.55 0.2s0.55
MO
0.08-O. IS 0.15-0.25 0. I s-025 0.08-o. IS 0.08-O. IS 0.08-0.15
titanium is generally confined to tool or other specialty steels. Tool steels and other highly alloyed steels are covered in other sections of this book. hlanganese. silicon. chromium. nickel. molybdenum. and vanadium all have their separate and unequal effects on hardenability. However, the individual effects of these alloying elements may be completely altered when two or more of these are used together. In periods of alloy shortages. extensive investigations were conducted. and it has been established that more hardenabilitj can be attained with less total alloy content when two or more alloys are used together. This practice is clearly reflected in the standard steel compositions shown in Table 7. This approach not only saves alloys that x2 often in scarce supply. but also results in more hardenability al lob4 er cost. Therefore. all of the steels listed In Tables 7 and 8 have significantly greater hardenability than the carbon steels listed in Tables 3 to 6. It must be further emphasized that the hardenability varies widely among the alloy grades. which is a principal reason for the existence of so many grades. It is oh\ ious that hardenability is an all important factor in the discriminating selection of a steel grade for heat treated parts. A standard procedure
Carbon & Alloy Steels Introduction
Fig. 3 Effect of Section Size on Surface Hardness of a 0.54 Carbon Steel. Quenched in water from 830 “C (1525 “F)
/ 117
Fig. 5 Method of Developing End-Quench Curve by Plotting Hardness Versus Distance from Quenched End. Hardness plotted every quarter inch for sake of clarity, although readings were taken in increments of one-sixteenth shown at top of illustration
Rockwell inch,
C as
Fig. 4 Standard End-Quench (Jominy) Test Specimen and Method of Quenching in Quenching Jig
for evaluating the hardenability of steels is necessary for initial selection as well as a tool for controlling quality.
Methods for Evaluating
Hardenability
A number of hardenability tests have been devised. each ha\ing its advantages and limitations. Most of these tests are either no longer used or their use is restricted to specialized applications. The endquench test has proved to be the method u ith the highest degree of reproducibility and has thus heen almost universally adopted for evaluating hardenability of virtualI> all standard alloy steels and for some grades of carbon steels. The test is relatively simple to perform and can produce much useful information for the designer as well as for the fabricator. Test Bars for the End-Quench Test. Although \ ariations are sometimes made to accommodate specific requirements, the test bars for the end-quench test are nomlally 25.5 mm (I in.) in diameter b> I02 mm (1 in.) long. A 25.5 mm (I in.) diameter collar is left on one end to hold it in a quenching jig. as illustrated in Fig. -I. In this test. the water flow is controlled by a suitable valve. so that the amount striking the end of the specimen (Fig. -I) is constant in volume and velocib. The Hater impinges on the end of the specimen onI). then drains away. By this means. cooling rates vary from about the fastest possible on the quenched end to very slogs. essentially equal to cooling in still air. on
the opposite end. This results in a u Ide range of hardnesses along the length of the bar. After the test bar has been quenched. tno opposite and flat pamllel surfaces are ground along the length of the bar to a depth of 0.381 mm (0.015 in.). Rocknell C hardnessdeterminations are then madeetery I.588 mm (0.60 in.). A specimen-holding indexing fixture is helpful for this operation for convenience as well as accuracy. Such fixtures are available as accessory attachments for conventional Rocknell testers. The next step is to record the readings and plot them on graph paper IO develop a curve, as illustrated in Fig. 5. Bj comparing the curves resulting from end-quench tests of different grades of steel. their relative hardenability may be established. The steels having higher hardenability will be harder a~ a given distance from the quenched end of the specimen than steels having lower hardcnabilit). Thus, the flatter the curve. the greater the hardenability. On the end-quench curves. hardness is not usually measured beyond approximately 51 mm (2 in.). because hardness measurements beyond this distance are seldom of an! significance. At about this 51 mm (2 in.) distance from the quenched end. the effect of uater on the quenched end has deteriorated. and the effect of cooling from the surrounding air has become signiticant. An absolutely flat txn P demonstrates conditions of very high hardenability \< hich characterize an air-hardening steel such as some of the highI> alloyed tool steels. u hich u ill be discussed later in this book. Variations in Hardenability. Because hardenability is a principal factor in steel selection and because hardcnabilit) varies over a broad range for the standard carbon and alloy steels. many grades are available. As a rule. hardenability of the standard carbon grades is very ION. although there is still a prsar deal of variation in hardenability among the
118 / Heat Treater’s
Fig. 6 End-Quench
Guide
Hardenability
Curve for 1541 Carbon
Fig. 6 Hardenability
Band for an Alloy Steel. 4150H: 0.47 to
0.54 C, 0.65 to 1 .I0 Mn. Normalized nealed at 845 “C (1555 “F)
Fig. 7 Hardenability
Curves for Several Alloy Steels
H and RH Steels Because of the normal variations within prescribed limits of composition. it would be unrealistic to expect that the hardenability of a given grade would always follow a precise curve such as shown in Fig. 6 and 7. Instead. the hardenability of any grade will vary considerably, which results in a hardenability band such as the 1150H hand in Fig. 8. This steel was normalized at 870 “C ( 1600 “F). then austenitized at 8-15 “C ( IS55 “F) before end quenching. The upper and lower curves that represent the boundaries of the hardenability band not only show the possible variation
“F). An-
in hardness at the quenched end, caused by the allowable carbon range of 0.47 to 0.5-t. but also the difference in hardenability as a result of the alloying elements being on the high or low side of the prescribed limits. The need for hardenability data for steel users has been recognized. Cooperative work by AlSl and SAE has been responsible for devising hardenability bands for a large numher of carbon and alloy steels, principally the latter. Steels that are sold with guaranteed hardenability bands are known as the H-steels. The numericaJ parts of the designation are the same as for the other standard grades. but the suffix letter H. such as 4lAOH. identifies it as a steel that will meet prescribed hardenability limits.
Chemical
different grades. This variation depends to a great extent upon the manganese content and sometimes to a smaller extent on the residual alloys which are sometimes present. A hardenahility curve for a high-manganese grade of carbon steel. 1511. is shobn in Fig. 6. This curve represents near maximum hardenability that can be obtained from any standard carbon grade. In contrast to the curve shohn in Fig. 6. typical hardenability curves for four different 0.50 carbon alloy steels are presented in Fig. 7. These data emphasize the fact that maximum attainable hardness is provided by the carbon content. while the differences in alloy content markedly affect hardenability. Hardenability also depends on grain size (i.e.. deoxidation practice) and melting practice (i.e.. BOF vs electric furnace). Electric furnace steel tends to have high levels of nickel. copper. chromtum. and molyhdenum residuals that improve hardenability. On the other hand, fine gained. alummum killed steels (premium grades with respect to formability) have lower hardenability than coarser grained. silicon killed steels.
at 670 “C (1600
Composition
Limits
Not all of the steels listed in Tables 3 to 8 are available as H or RH steels, although most of the alloy steels can be purchased as H-grades. Tables 2. 9. and IO list those carbon and alloy grades which are presently availahle as H or RH steels. In order to give steel producers the latitude necessary in manufacturing for common hardenability limits. the chemical compositions of normal grades have been modified to form the H and RH steels. These moditications permit adjustments in manufacturing ranges of chemical composition. These adjustments correct melting practice for individual plants which might otherwise influence the hardenability bands. However, the modifications are not great enough to influence the general characteristics of the original compositions of the steels. Figure 8 is presented merely as an example of a hardenability band. In the section which follows. the hardenahility bands. if available. are included hith heat treating and other data for individual carbon and alloy steels. Restricted hardenability (RH) steels are defined in SAJZ Jl868. Composition ranges are the same as those for the standard alloy grades. and hardenahility hands are narrower than those for the H grades. For example. 3130 and -II-IO RH have the same specified composition ranges, while -II-IO H has broader ranges. The Jominy hardenability band of4130 RH is about half the width of the -II10 band. RH grades open the door to substantial benefits to the heat treater. A major metalworking company. for instance. had a part forged to four different dimensions. Four different procedures were required to heat treat the parts to a set of common properties. Restrictive steel chemistries eliminated the need for the four procedures and made it possible to consolidate specifrcations. The RH grades also made it possible to design a new specilication that provides Jominy hardenability bands lying with the overlap of tUo older specifications. Over a five year period, this company was able to reduce its material specifications in this manner from a total of 3 I down to nine.
Carbon & Alloy Steels Introduction
Alloying I Elements. Source: Climax Molybdenum
/ 119
120 / Heat Treater’s
Guide
Carbon Plus Grain Size. Source: Climax Molybdenum
Carbon (1000,
Steels
1100,1200,
and 1500 Series)
introduction Carbon steels are now classified in four distinct series, in accordance with the AlSl system of designations: the 1000 series. which are plain carbon steels containing not more than I .OO Mn maximum; the I100 series, which are resulfurized carbon steels; the 1200 series, which are resultiu-ized and rephosphorized carbon steels: and the I500 series. which are high-manganese (up to 1.65) carbon steels and are nonresulfurized. These four series differ in certain fundamental properties, thus justifying the series differentiation. However, in temls of their response to heat treatment, all four series can be discussed in temts of their carbon content, the principal controlling factor in heat treating. Other factors areconsidered for the individual steels on the pages that follow. To simplify consideration of the treatments for various applications. the steels in this discussion are classified as follows: Group I, 0.08 to 0.25 C; Group II. 0.30 to 0.50 C: Group lfl. 0.55 to 0.95 C. A relatively few steels. such as 1026 and 1029. can be assigned to more than one group. depending on thetrcarbon content. Group I(O.08 to 0.25% C). The three principal types of heat treatment used on these low-carbon steels are: (aj process treating of material to prepare it for subsequent operations; (b) treating of finished parts to improve mechanical properties: and t,c) case hardening. notably by carburizing or carbonitriding, to develop a hard, wear-resistant surface. It is often necessary to process anneal drawn products between operations, thus relieving work strains in order to permit further working. This operation is normally carried out at temperatures between the recrystallization temperature and the lower transformation temperatures. The effect is to soften by recrystallization of the grain growth of ferrite. It is desirable to keep the recrystallized grain size relatively fine. This is promoted by rapid heating and short holding time at temperature. A similar practice may be used in the treatment of low-carbon, cold-headed bolts made from cold-drawn wire. Sometimes the strains introduced by cold working so weaken the heads that they break through the most severely worked portion under slight additional stratn. Process annealing is used to overcome this condition. Stress relieving at approximately 540 “C t 1000 “F) is more effecttve than annealing in retaining the normal mechanical properties of the shank of the cold-headed bolt. Heat treating is frequently used to improve machinability. The generally poor machinability of the low-carbon steels. except those containing sulfur or other alloying elements. results principally from the fact that the proportion of free ferrite to carbide is high. This situatton can be modified by putttng the carbide into tts most voluminous form, pearlite. and dispersing tine particles of this pearlite evenly throughout the ferrite mass. Normalizing is commonly used with success. but best results are obtained by quenching the steel in oil from 815 to 870 “C (1500 to 1600 “Fj. With the exception of steels containing a carbon content approaching 0.255,. little or no martensite is formed. and the parts do not require tempering. Group II (0.30 to 0.50% C). Because of the higher carbon content. quenching and tempering become increasingly important when steels of this group are considered. They are the most versatile of the carbon steels. because their hardenability (response to quenching) can be varied over a wide range by suitable controls. Ln this group of steels. there is a continuous change from water-hardening to oil-hardening types. Hardenability is very sensitive to changes in chemical composition. particularly to the content of manganese. silicon. and residual elements, as well as gram size. These steels are also very sensitive to changes in section.
The medium-carbon steels should be either normalized or annealed before hardening in order to obtain the best mechanical properties after hardening and tempering. Parts made from bar stock are frequently given no treatment prior to hardening (the prior treatment having been performed at the steel mill). but it is common practice to normalize or anneal forgings. These steels. whether hot Fished or cold finished, machine reasonably well in bar stock fomt and are machined as received, except in the higher carbon grades and small sizes that require annealing to reduce the as-received hardness. Fotgings are usually normalized to improve machinability over that encountered with the fully annealed structure. These steels are widely used for machinery parts for moderate duty. When the parts are to be machined after heat treatment, the maximum hardness is usually held to 320 HB and is frequently much lower. In hardening. the selection of quenching medium will vary with the steel composition. the design of the part. the hardenability of the steel, and the hardness desired in the finished part. Water is the quenching medium most commonly used. because it is best known and is usuaUy least expensive and easiest to install. Caustic soda solution (5 to 10% NaOH) is used in some instances with improbed results. It is faster than water and may produce better mechanical properties in all but light sections. It is hazardous, however. and operators must be protected against contact with it. Salt solutions (brine) are often successfully used. They are not dangerous to operators. but their corrosive action on iron or steel parts or equipment is potentially serious. When the section is light or the properties required after heat treatment are not very high. oil quenching is often used. Finally, the medium-carbon steels are readily case hardened by flame or induction hardening. Group Ill (0.55 to 0.95% C). Forged parts made of these steels should be annealed because: l
l
Refinement of the forged structure is important in producing a high quality, hardened product The parts come from the forging operation too hard for cold trimming of the flash or for any machining operations
Ordinary annealing practice. followed by furnace cooling to approximately 600 “C t I I IO “F) is satisfactory for most parts. Hardening by conventional quenching IS used on most parts made from steels in this group. However. special techniques are required at times. Both oil and water quenching are used: water. for heavy sections of the lower carbon steels and for cutting edges: oil. for general use. Austempering and martempenng are often successfully applied. The principal advantages of such treatments are considerably reduced distortion, elimination of breakage. and. m many instances. greater toughness at high hardness. Tools with cutting edges are sometimes heated in liquid baths to the lowest temperatures at which the part can be hardened and are then quenched in brine. The fast heating of the liquid bath plus the low temperature fail to put all of the available carbon into solution. As a result. the cutting edge consists of martensite containing less carbon than indicated by the chemical composition of the steel and containing many embedded particles of cementite. In this condition. the tool is at its maximum toughness relative to its hardness, and the embedded carbides promote long life of the cutting edge. Final hardness is SS to 60 HRC. Steels in this group are also commonly hardened by Flame or induction methods.
122 / Heat Treater’s
Guide
Effect of mass and section size on cooling curves obtained for the water quenching of plain carbon steels
Carbon
Steels (1000, 1 100,1200,
Effect of mass and section size on cooling curves obtained for the oil quenching of plain carbon steels
and 1500 Series) / 123
124 / Heat Treater’s
Guide
Influence of tempering temperature on room-temperature
hardness of quenched carbon steels
Carbon
Influence of tempering temperature on room-temperature
Steels (1 000, 1 1 00.1200,
and 1500 Series) / 125
hardness of quenched carbon steels (continued)
126 / Heat Treater’s
Guide
Room-temperature hardness of three carbon steels after production tempering. (a) Automotive steering-arm forgings made of fine grain 1035 steel. Section thickness varied from 16 to 29 mm (5/8to 1 ‘/sin.). Forgings were austenitized at 625 “C (1520 “F) in oil-fired pushe conveyor furnace, held 45 min. quenched in water at 21 “C (70 “F), and tempered 45 min at 560 to 625 “C (1080 to 1160 “F) in oil-fired link belt furnace to required hardness range of 217 to 285 HB. Hardness was checked hourly with a 5% sample; readings were taken on polishec flash line of 29 mm (1 l/s in.) section. Survey of furnace revealed temperature variation at 605 “C (1120 “F) of 8, -4 “C (15, -7 “F). Data rep resent forgings from four mill heats of steel and cover a 6-week period. (b) Woodworking cutting tools forged from 1045 steel. Section o cutting lip was hardened locally by gas burners that heated the steel to 815 “C (1500 “F). Tools were oil quenched and tempered at 305 tc 325 “C (585 to 615 “F) for 10 min in electrically heated recirculating-air furnace to a desired hardness range of 42 to 48 HRC. Data wen recorded during a g-month period and represent forgings from 12 mill heats. (c) Plate sections, 19 to 22 mm (3/d to 7/8 in.) thick, of 1045 stee were water quenched to a hardness range of 534 to 653 HRB and tempered 1 h at 475 “C (890 “F) in continuous roller-hearth furnaces. Dat: represent a e-month production period. (d) Forged 1046 steel heated to 830 “C (1525 “F), and quenched in caustic. Forgings were heater in a continuous belt-type furnace and individually dump quenched in agitated caustic. Forgings weighed 9 to 11 kg (20 to 24 lb) each; maxi mum section, 38 mm (1 l/2 in.). (e) As-quenched forged 1046 steel shown in (d), tempered at 510 “C (950 “F) for 1 h. (9 As-quenched forget 1046 steel shown in (d), tempered at 525 “C (975 “F) for 1 h. Average hardness data for all but (c) obtained by calculating average of higt and low extremes of hardness specification range for each batch.
Carbon
Steels (1 000, 1 100,1200,
and 1500 Series) / 127
1062: Heat-to-Heat Variations in Depth of Hardness. Heat-to-
heat variations in depth of hardness among three heats. Hubs were flame hardened on the inside diameter to a minimum of 59 HRC at 1.9 mm (0.075 in.) below the surface. Parts were heated 12 s and quenched in oil. Hardness was measured on cross sections of heated area.
1052 and 1062: Flame hardening hubs. Distribution of dimensional change as a result of flame hardening. (a) Change in pitch diameterof converter gear hubs made of 1052 steel. Gear teeth on inside diameter were heated for a total of 9.5 s. before being quenched in oil to provide a depth of hardness of 0.9 mm (0.035 in.) above the root. (b) Close-in of inside diameters of converter hubs made of 1062 steel. Inside diameter was heated for a total of 12 s and then oil quenched to harden to 59 HRC min at a depth of 1.9 mm (0.075 in.) below the surface. Inside diameter was finish ground after hardening.
128 / Heat Treater’s
Guide
1018 and 1024: Gas carburizing.
Effect of tempering 4.5 h, then oil quenched and tempered.
on hardness of 1018 and 1024 steel. Parts were carburized
at 925 “C (1700 “F) for
Carbon
Effect of time and temperature on case depth of liquid carburized steels
Steels (1000, 1 1 00,1200,
and 1500 Series) / 129
130 / Heat Treater’s
Nitriding
Guide
Carbon Steels. Effect of carbon content in cation
steels on the nitrogen gradient obtained in aerated bath nitriding
Typical Steels
Normalizing
Temperatures
for Standard
Carbon
Ikmperatore(a) Grade Plain carbon steels lOIS I020 1022 102.5 I030 1035 IO-IO IW5 IO50 1060 1080 1090
IWS 1117 1137 II-II II-U
“C
OF
915 915 915 900 900 885 860 860 860 830 830 830 835 900 885 860 860
167.5 1675 I675 1650 1650 1625 1575 1575 1575 lS25 1525
1575 1550 1650 1625 1575 1575
(a) Based on production experience. normalizing temperature may vary from as much as 27 “C (50 “F) beloa. to as much as 55 “C ( IO0 “F) above. indicated temperature. The steel should be cooled in still air from indicated temperature.
Properties AM grade(a) 1015
1020
I022
1030
IWO
IOSO
1060
I080
1095
III7
III8
1137
of Selected
Carbon Steels in the Hot-Rolled,
Condition ortreatment As-rolled Normalized at 9’S “C ( I700 T) Annealed at 870°C ( 1600 “Fj As-rolled Normalizedat 87O”C( 1600°F) Annealed at 870 “C ( I600 “FJ As-rolled Normalized at 925 “C ( I700 OF) Annealed at 870 “C ( I600 “f? As-rolled Normalized at 9’S & “C ( I700 “F) Annealed at &t5 “C ( I S50 “F) As-rolled Normalizedat9OO”Ct 1650°F) Annealed at 790 “C ( 1150°F) AS-ldkd Normalized at 900 “C ( 1650 “F, Annealed at 790 “C ( I -ISO “R As-rolled Normalized at 900 “C t I650 “F) Annealed at 790 “C ( 1150 “F) As-rolled Normalizedat 900°C (165O”F1 Annealed at 790 “C ( 1450 “F)
As-rolled Normalized Annealed at As-rolled Normalized Annealed at As-rolled Normalized Annealed at As-rolled Normalized Annealed at
at 900 “C ( I650 “F) 790 “C ( 1450 “F) at 900 “C ( 1650 “FJ 860 “C ( IS75 “F) at 925 “C ( 1700°F) 790 “C ( I150 OF) at 900 “C (1650°F) 790 “C ( l-l.50 “FJ
Tensile strengtb ksi MPa 420 -125 385 150 UO 395 SOS 185 450 5.50 525 160 620 995 520 725 750 635 815 775 625 964 1015 615 965 lOIS 655 190 -170 130 525 -175 150 625 670 985
61 62 56 65 64 57 73 70 65 80 76 67 90 86 7s 10s 109 92 II8 II3 91 I-IO 117 89 I10 117 95 71 68 62 76 69 65 91 97 as
Normalized,
Keld strength k5i MPa 315 325 285 330 31s 29.5 360 360 31s 315 345 3-15 -l15 370 350 415 130 365 385 3’0 370 585 s2s 380 570 so5 380 SOS 305 28.5 315 315 285 380 -loo 34s
46 -I7 JI -I8 50 43 52 52 46 SO SO SO 60 5-l 51 60 62 53 70 61 4-l 8S 76 59 83 73 55 4-t 4-l -II -WA -I6 -II 55 58 50
and Annealed
Conditions q ardness,
Elongation(b),
Reduction in area, 9%
HB
Imd impact strength ft. Ibf J
61 70 70 59 68 66 67 68 6-l 57 61 58 SO 5.5 57 10 39 -IO 3-l 37 38 17 21 -IS I8 I-l 21 63 s-1 58 70 66 67 61 -19 s-l
I36 121 III l-13 I31 III 149 I13 I37 179 l-I9 I26 201 170 lJ9 229 217 I87 Yl 229 179 293 293 171 293 293 I92 143 137 121 119 I13 I31 192 197 17-l
III I15 II5 87 II8 I23 81 117 121 75 94 69 49 65 35 31 27 I8 18 I-l II 7 7 7 3 5 3 81 85 94 lo9 103 107 83 63 SO
39.0 37.0 37.0 36.0 35.8 36.5 35.0 B-I.0 35.0 32.0 32 0 312 2s 0 28.0 30.2 20.0 23.7 17.0 I8.O 22.5 17.0 I I.0 23.7 9.0 95 13.0 33 0 33.5 32.8 32.0 33.5 31.5 28.0 22.5 26.8
4%
82 85 85 64 87 91 60 87 89 55 69 51 36 48 33 23 20 I3 13 IO 8 5 5 5 3 ‘I 2 60 63 69 80 76 79 61 17 37
Carbon
Properties AlSl grade(a) 1141
114-l
of Selected
Carbon Steels in the Hot-Rolled,
Condition or treatment
field strength ksi MPa
Tensile strength MPa ksi
As-rolled Normalized at 900 “C ( 1650 “Fj Annealedat81S°C(ISOO”F) As-rolled Normalized at 900 “C ( 16.50 “F) Anneakd at 790 “C ( I-150 “R
675 710 600 705 670 585
Normalized,
98 103 87 102 97 89
360 40s 3.55 420 ml 31.5
Steels (1000, 1 1 00,1200,
and 1500 Series) / 131
and Annealed
Conditions
Elongation(b),
Reduction in area, %
Hardness. RB
38 56 19 -II 40 JI
192 201 163 212 197 167
52 59 51 61 58 50
?O
22.0 22.7 25.5 21.0 21.0 24.8
(continued) Imd impact strength B Ibf J II 53 34 53 43 65
8 39 25 39 32 18
(a) All grades PIE tine grained except for those in the I 100 series. m hich are coarse grained. (h) In SO mm or 2 in.
Effect of Mass on Hardness Alloy Steels
Grade
Normalizing temperature “F “C
Carbon steels, carburizing lOIS I020 1022 III7 III8
92s 92s 92s 900 925
92s 900 900 900 900 900 900 900 900
Critical
Temperatures
5w.a
I26 I31 1.43 I43 IS6
IZI I31 I13 137 I13
II6 I26 137 I37 137
II6 I21 I31 I26 131
l5b 183 223 229 293 302 201 207 201
l-+9 170 217 229 293 293 197 201 197
137 167 212 223 285 ‘69 197 XI I92
137 167 201 223 269 ‘55 192 201 I91
heats
Carbon Steels
Steel
Critical temperatures on beating at 28 “C/h (50 OF/h) ACI ACJ OF T OF T
1010 I020 I030 I040 1050 1060 1070 1080
72s 725 72s 725 72s 72s 725 730
I335 1335 133s 1335 133s 1335 1335 I315
875 845 815 795 770 745 730 735
1w4
grades
1700 1650 l6SO 1650 1650 1650 1650 1650 1650
for Selected
231)
13(‘4
grades
Note: AU data are based on male
Approximate
Carbon and
Hardness, HB, for bar with diameter, mm (in.), of
1700 1700 1700 1650 I700
Carbon steels, direct-hardening 1030 1040 1050 1060 lo80 1095 1137 I I-II II-U
of Normalized
1610 ISSS I-195 I460 111s I375 I390 13%
Critical temperatws h-3 OF OC 850 815 790 75s 740 72s 710 700
I560 I SO0 I -Is0 139s I365 I%+0 1310 1290
on cooling at 28 OC/b (SOOF/b) h “C OF 680 680 675 670 680 685 690 695
1260 1260 I250 I240 1260 I 265 I275 I280
132 / Heat Treater’s
Recommended
Guide
Temperatures
and Cooling
Cycles for Full Annealing
of Small Carbon Steel Forgings
Data are for forgings up to 75 mm (3 in.) in section thickness. Time at temperature thick; l/2 h is added for each additional 25 mm (1 in.) of thickness.
usually is a minimum of 1 h for sections up to 25 mm (1 in.)
Cooling cycle(a) Annealing temperature T OF
Steel
ass-900 aswoo aswoo ass-900 84s.88s 845-8x5 790.870 790-870 790-870 790-84s 790-84s 790-84s 790.830 790-830
lo18 I ox IO22 lo25 1030 1035 IO4O IONS 1050 lO6O I070 I 080
(a) Fumasecoolingar
OF
T
1575-1650 lS7S-1650 lS7S-1650 ls75-1650 1550-162.5 ISSO- I625 IJSO-IhOO 1X50- I600 l-150-I600 l-150- I550 IGO- 1550 1150-1550 1150-1525 11so-IS25
From
To
From
ass ass 855 85s 845 84s 790 790 790 790 790 790 790 790
70s 700 700 700 6.50 650 650 650 650 6SO 650 650 6SO 655
IS75 IS75 IS75 IS75 IS50 ISSO 1150 l-150 1150 1150 l-Pi0 I450 14.50 1450
To
Eardness range, FIB 111-119 Ill-149 111-119 Ill-187 126-197 137-207 137-207 156.217 156-217 156-217 167-229 167-229 167.229 167-219
28”C/h(5O”F/h)
Approximate Grossmann Quenching Severity Factor of Various Media in the Pearlite Temperature Range Circulation or agitation
Brine
None Mild hlodersre GOOd Strong Violent
Grossmann
Numbers
2 -7-7-.- 7
hater
and Film Coefficients
32
90
55
130
F&I oi I
60
I10
2%
13
II0
polp\ rn) I py-rolidone
Conventional hlancmpering Air
oil oil
69 I so 77
09-1.0 1.0.I.1 1.2-I.? I-l-l.5 I 6-2.0 -I
5
Quenchant temperature “F T
Quenchant
Grossmann quench seberityfactor, Water Oil and salt
150 300 80
for Selected
0.25-o 30 0.30-0.3s 0.35-O 10 0.40 5 0 S-O.8 o.a-I.1
Air 0.01
Quenchants
Quenchant belocih ft/min m/s 0.00 0.25 0.51 0.76 0.00 0.25 03 I 0.76 0.00 0.3 0.5 I 0.76 0.00 0.25 0.5 I 0.76 0.51 0.5 I 0.00 2 s-l 5 ox
H
0 50 loo IS0 0 SO IO0 I50 0 50 loo IS0 0 50 loo I so loo loo 0 500 I ooo
Grossmann number, (H=h/2k)
I.1 21 1.7 2.8 0.2 0.6 I5 2.-l 0.s I .o I.1 I.5 0.8 1.3 I .s 1.8 0.7 I.2 0.05 0.06 0.08
Effectke fdm coefficient w/m2 K Btu/ft’ h OF so00 9ow
880
I’OMI 12OOO IO00 2500 6500 IO5oo xoo -1500 sooo 6500 3.500 6GOO 6500 7500 3ooo sooo 200 250 350
2100 2100 la0 440 Iloo 1x50 350 790 880 I200 620
II00 1100 I300 530 880 3s 44 62
Carbon
Comparison of the Cooling Power of Commercially Magnetic Quenchometer Test Results
Oil sample
Types of quenching oil Conventional
Fcljt
Martempering.
without speed improvers
Martempering.
with speed irnprobers
(a) SW
Saybolt universal
Comparison to Magnetic
Typical
Grade
Viscosity at 40 T (1~W SUS(a)
Quenching
105 107 so 9-t 107 II0 I20 329 719 ‘550 337 713 2450
“C
OF
190 19.5 I 70 l-t.5 170 190 ias 190 23s 245 300 230 2-15 300
37s 380 340 290 33s 37s 370 375 45s 475 575 150 475 570
and 1500 Series) / 133
Oils According
to
Quenching duration from 885 T (1625 “I9 to 355% (t i70°F),s At 27OC (80 OF) At 120°C ( 2soT) Chromized Chromized Ni-ball Ni-ball Ni-ball Ni-ball 12.5
‘7.2 27.9 24.8 (a) IS.0 17.0 19.6 17.8 27.6 19.0 32.0 fbl 179 17.0
17 a 16.0 7.0 9.0 lo.8 12.7 13.3 19.2 26.9 31.0 IS.3 16.-l 19.7
la.4 25. I 31.7 12.8 IA.0 IS.1
2’. I 30.4 32.8 (hJ IS.6 IS.4
seconds. fb) Not a\uilahlc
of the Ranges of Cooling Power of Commercially Available Quenchometer Test Results using Pure Nickel Balls
Hardnesses
of Various
Quenching
Quenchingduration from885T At 120 ‘T (250 OF)
At 65 T (15OT) Id.22 7-l-t 18-3-l I420
L+ithout speed imprmers with speed improvers
Carbon content, %
and Mat-tempering
Flash point
IO?.
I 2 3 3 5 6 7 8 9 IO II I’ 1; II
‘@pe of quenching oil Conventional Ftisl Martempering, Martempeting.
Available
Steels (1000, 1100,1200,
(1625T)
and Martempering to355”C At 175°C
Oils According
(670 “F), s At 23oT
(350 “F)
(450 “F)
21-38 16-27
47 =33
I-t-22 7-14
ix-34 13.18
Carbon Steels after Tempering Hardness, ARC. after tempering for 2 h at
205 “C
260 T
315-x
370 “C
425T
48oT
595 T
650 OC
(400°F)
(500°F)
(6OOW
(7OO’T)
@OO°F~
(900°F)
(MOOoF)
540-T
(1100°F)
(12OO’=F)
Heat treatment
Normalized at 900 “C ( I650 “Ft. water quenched From 830-845 “C t 1525 I SSO “FL averuae de\s point. I6 “C (60 “F)
Carbon steels, water hardening I030
0.30
50
15
43
39
?I
28
25
22
9Sta)
I040 1050 1060
0.40 0.50 0.60
51 S? 56
48 50 SS
46 16 so
11 4-l 42
37 10 38
30 37 37
27 31 SS
22 29 33
943, 22
I 080 109s II37
0.80 0.95 O.-lo
S7 58 4-l
55 57 12
so 52 -IO
13 -17 37
-II 43 33
10 12 30
39 -II 27
38 10 ‘I
3’ ;; 91111)
II-II 11-l-l
0.40 0.40
19 5s
46 50
43 -17
-II 45
38 39
31 32
28 ‘9
23 25
94at 97ta1
Data uere obtained on 25 mm r I in.) buts adequately
quenched to drielop
full hurdnrss. ISI Hardness. HRB
26
Normalized ut 885 “C I 1625 “Ft. water qucnchrd from 800-S IS ‘T ( 1175. lSOO°Ft; aberage dea potnt. 7 “C (-IS “F)
Nomtalizcd at9OO‘C t 1650°F). \raterqucnched from 830-855 ‘T t I S?S- I575 “FL average dew point 13Tt.55 “F)
134 / Heat Treater’s
Guide
Carbon Steels: Typical
Austempering
Applications
Parts listed in order of increasing section thickness
Part
Maximum seclion thickness l22Ul in.
Steel
Parts per unit weight lb kg
Salt temperature OC OF
Immersion time, mia
Eardness, ERC
Plaii carbon steel parts Clevis Follower arm Sp-ing PhUe Cam lever Plate -bPc~ Tabulator stop Lever Chain link Shoe-last link Shoe-toe cap Lawn mower blade Lever Fastener Stabilizer bar Boron steel bolt
IO50 IO50 1080 1060 1065 1050 106s 106s IOSO 1050 1065 I070 1065
3.18 6.35 I9 6.35
107.5 1060 1090 IOBZO
Typical Operating Section size mm in.
0.75 0.75 0.79 0.81 I .o I .o I .o I .I?:! I .2s I .s I .s I.5 3.18
Conditions
Material
0.030 0.030 0.03 I 0.032 0.040 0.010 0.040 0.048 0.050 0.060 0.060 0.060 0 12s
77olkg 412/kg 22Olkg 88/Q
0.125 0.250 0.750 0.250
wkg IlO/kg 22 kg lOOIkE
for Through
Frequency(a), Ez
Power(b), kW
3SO/lb I87Iib lOO/lb
4011b
62Jh
28Ilb ‘A lb 6-Vlb
0.5 kg 14lnig -uokg
2oonb
s73lkg 86Aig l8nig 1.5 kg
Hardening
39nb 8/lb ?, lb llnb
SO/lb IO lb
Jsnb
360 35s 330 330 370 360 370 360 34s 34s 290 31s 31s
680 675 625 630 700 675 700 680 650 650 550 600 600
IS IS I5 6 IS I5 IS IS IS IS 30 60 IS
42 42 48 45-W 42 42 42 4s 45-50 45 52 so so
385 310 370 420
725 590 700 790
5 25 6-9 5
30-3s 50 40-45 3843
Carbon Steel Parts by Induction
Process
Total beating time, s
Scao time s/cm Sri.
68.4 28.8 98.8 -14.2 11-l 51
0.71 0.71 I .02 I .03 I.18 I.18
I.8 I.8 2.6 2.6 3.0 3.0
7s 620 70 620 7s 620
I65 II50 160 II50 I65 II50
620 955 620 95s 620 955
II50 I750 II50 I750 II50 17.50
II3 II3 I41 I41 IS3 I53
250 250 311 311 338 338
0.085 0.054 0.057 0.053 0.050
II.3 IS 28 5 26.3 36.0
0.59 0.79 I SO 1.38 1.89
I .s 2.0 3.8 3.5 1.8
20 20 20 20 20
70 70 70 70 70
870 870 870 870 870
1600 1600 1600 I600 1600
lU9 IS76 1609 IS95 1678
3194 3474 3548 3517 3701
0.361 0.319 0.206 0.225 0.208
2.33 2.06 I .33 I.45 I .34
0.94
2.4
20
70
885
162.5
2211
4875
0.040
0.26
Work temperature Entering coil Leaving coil OC ‘=F “C “F
Production rate lb/h kslb
Inductor input(c) kW/cmz kW/i&
Rounds I9
‘4
1035 mod
25
I
lo-11
29
I ‘Ix
1041
I80 9600
%? 34 ‘4 I I ‘/8
1038 1038 1043 1036 1036
3000 3000 3000
300 332 336 304 311
3OQO
580
28.5 20.6 33 19.5 36 19.1
Flats I6 I9 12 25 29
Irregular
shapes
17.5-33
“/16-1Vlb
1037 mod
25-l
Ia) NOW use ofdual frequencies for round secuons. (b) Po\rer transmitted by the inductorat the operaung frequency mput IO the machine. because of losses within the machine. (c) AI the operating frequency of the inductor
indicated.
This poner is approximarely
2%
less than the power
Carbon
Operating
and Production
Section size in. mm
Material
Data for Progressive
Frequency, Ez
Power(a), kH
Induction
Total beating time, s
Steels (1000, 1 1 00,1200,
and 1500 Series) / 135
Tempering
Scan time s/cm Sri.
Work temperature EnbXillg Leaving coil coil T OF “C “F
0.71 I .02 I.18
I.8 2.6 3.0
so so SO
I’0 I20 I20
510 565 565
0.59 0.79 I SO I.22 1.57
I .s 2.0 3.8 3.1 4.0
40 40 40 -lo 40
IlKI 100 IO IO0 100
290 315 ‘90 290 290
0.94 0.67
2.-l 1.7
65 65
I50 IS0
550 -125
Production rate lblh kP
Inductor input(b) kW/cm2 kW/ii.’
Rounds I9 2s 29
% I I Vs
1035 mod 1041 1041
9600 9600 9600
12.7 18.7 20.6
% % ‘4 I I ‘/x
1038 I038 1043 IoJ3 1043
60 60 60 60 60
88 100 98 85 90
1037 mod 1037 mod
9600 9600
I92 IS-l
30.6 44.2 51
950 IO50 1050
II3 I41 IS3
30 311 338
0.050 0.054 0.053
0.32 0.35 0.34
I449 IS76 I609 I365 l-183
3194 3171 3548 3009 3269
0.014 0.013 0.008 0.011 0.009
0.089 0.08 I 0.050 0.068 0.060
2211 2276
-1875 SO19
0.043 0.040
0.28 0.26
Flats I6 I9 22 25 29
123 16-l 312 25-l 328
SW 600 990 SSO 550
Irregular shapes 17.5-33 17.529
)‘/)e-15/)b )&-I l/x
64.8 46
(a) Power transmitted by the inductor ar the operating frequency indicated. For convened because of losses within the machine. (b) AI the operating frequency of the inductor
1062: Preliminary
Spot Flame Hardening
of a Free-Wheel
this power is approximately
254
less than the power inpur to the machine,
Cam Hardness and pattern aim
operation
Turn on water. air, oxygen. power. and pmpane. Line pressures: water. 205 kPa (30 psi); air, 550 kPa (80 psi): oxygen. 82S kPa ( I20 psi): propane. 205 kPa (30 psi ). Ignite piloa.
Loading and positioning Mounr cam on flame head. Cam positioned on locating plaw and MO wear pads. and against three locating pins lhar are imegral pans of flame head. Disurnce from flame head to cam surface. appmximalely 7.9 mm &)r, in.)
Cycle start and heating cycle Propane and oxygen solenoid valves open (oxygen flow delayed slightly). Mixture of propane and oxygen ignited a1 flame heads hy pilots. Check pmpane and oxygen pressures, Adjust flame by regulating pmpane. Heating cycle controlled by timer. lime predetermined toobtain specilied hardening depth. Propane and oxygen solenoid valves close (propane flow delayed slightly). Ejector plate (air operated) advances and suips cam horn flame head. Propane regulaled pressure. I25 kPa ( I8 psi); oxygen regulated pressure, 585 kPa (89 psi ): oxygen upsu-eam pressure. 425 kPa (62 psi); oxygen dounstream pressure. I IO kPa ( 16 psi). Flame velocity (approximate). I35 m/s (-150 ft/s). Gas consumption (approximate): pmpane. 0.01 m3 (0.4 ft3) per piece: oxygen. 0.04 m3 ( I .3 ft3) per piece. Total heating time. I I s Flame pm design: nine ports per row; eight mws; port size. No. 69 (0.74 mm. or 0.0292in.).whhNo.S6(1.2 mm.orO.O-%Sin.)counterbore
Quench cycle Cam drops into quench oil. is removed from tank by conveyor. S.6”C( l30f 10°F). Tie inoil (approximate), 30s
frequencies.
I020 800
Oil lemperarure.
S-1f
Hardness. 60 HRC minimum ar surface and 59 HRC minimum al adepth of I .3 mm (0.050 in.) below surface. for\sidrh of 8.8 mm (0.345 in.) on cam rollersurface. Dimemions below gven in inches
136 / Heat Treater’s
Guide Gas Carburizing:
Flame Hardening
Response
of Carbon Steels
Material
‘Qpical hardness, ERC, as affected by quenchant Air(a) Water(b) OW)
Steel
Carburized
SO-60 55-62
Q-S8 58-62 58-62
-15-55 so-55
52.S7lC) SS-60
33-50 55-60 60-63 62-65 IS-55 55-62 58-6-l
1010 1018 1019 1020 1021 IO’.! 152-l IS17
62-65 62-65
Resulfurized
grades of plain carbon steels(d)
1010-1020 1108-1120
Steel Compositions Composition, % Ni Cr
C
Mn
0.08-0.13 0.15-O 70 0. IS-O.20 0.1X-0.23 0.18-0.23 0.18-0.23 0 19-O 25 0’1-029
0.30-0.60 0.60-0.90 0.70-I .OO 0.30-0.60 0.60-0.90 0.70-1.00 1.3.31-1.65 1.20-1.50
MO
Other
:::
la).(b) (a).(b) (a). lb) (a). fb) W.(b) (a). fb) (a,.(b)
Carbon steels
Plain carbon steels 102S- 103s IcU@lost~ 10.55-1075 1080-1095 11~5-1137 1138-114-l II46llfil
Carburizing
5X-61
50-b0 SO-60
60-63
III7
:::
.._
_..
(a).(b)
steels 0.140’0
100-l
30
0.08-o. I3 S
tat Toobtain the hardness results indicated. those areas not dtrestly heated must be kept relatively cool during the heating process. tbl Thin sections are susceptible to cracking when quenched utth oil or water. tc) Hardness is slightly lower for material heated h) spinningorcombination progressike-spinning methods than it is for material heated by progresstbe or stationq methods. (di Hardness values of carburized cases containing 0.9oto I.IOQC
Effect of Cyaniding
Temperaturesand
Time on Case Depth and Carbon and Nitrogen
Contents
Material thickness, 2.03 mm (0.080 in.); cyanide content of bath, 20 to 30% Case depth after cjaniding steel
Anal)& after 100 min at temperature(a) Carbon, % Nitrogen, %
for:
15 min
100 min
mm
in.
mm
in.
0.038 0.038 0.05 I
0.0015 0.001s 0.0020
0.152 0.151 0.203
O.OOb 0.006 0008
068 0.70 cl.7L
0.5 I 0.50 051
0.076 0.076 0.089
0.0030 0.0030 0.0035
0.203 0.203 0.3-l
0.008 0.008 0.010
0.75 0.77 0.79
0.26 0.28 0.27
Cyanided at 76O’C (1400 “F) 1008 IOltl 1022
Qanided 1008 I010 IO’2
at 845 OC (1550 OF)
tat Carbon and nitrogen contents were determined
from analysis of the outermost
0.07b mm 10.003 in. J of cytnidsd
cases.
Carbon
Liquid Carburizing Typical application
Carbon Steels in Cyanide
of carbon steel and resulfurized Weight
Part
Steels (1000, 1100,1200,
and 1500 Series) / 137
Baths
steel Depth of case mm in.
Temperature T OF
kg
lb
Steel
0.9 0.5 0.7 3.5 I.1 I .-I 0.03 0.09 09 1.75 0.05 0.007 0.007 0.7 0.15 7.7 0.05
2 I.1 1.5 7.7 2.5 3 0.06 0.’ 2 10,s 0.12 0.015 0.015 I .b I 17 0. I
CR 1020 CR IO20 CR I020 1020 ION CR 1020 1020 1018 1010 CR IO20 CR IO22
I .o I.5 I.5 1.3 1.3 I.3 0.1-0.5 I .s I .o 1.3 0. I3-0.25 0.13-0.2s 0.25-0.-l I.5 I .s 1,s 0.02-0.0.5
0.040 0.060 O.ObO 0.050 0.050 0.090 0.0 I s-o.020 0.060 0.040 0.0.50 0.005-0.010 0.00.5-0.010 0.010-0.015 0.060 0.060 0.060 0.00 I-O.002
940 940 910 940 910 910 81.5 940 910 940 8-15 845 81S 940 940 910 900
I720 I720 1720 I720 I720 I720 ISSQ I720 I720 I720 IS50 1550 1550 I770 17’0 17’0 1650
0.0-l 3.6 0.0009 3.6 02 0.0-l O.W3 0.007 0.31 0.0 I 0003 0.08 0.009 0.9 0.007 0.02 O.-IS 0.007
0.09 8 0.00~ 8 0.5 0.09 0.007 0.015 0.75 0.03 0.007 0.18 0.02 2 0.015 0.05 I 0.015
III8 III7 III8 III7 III7 III3 III9 III3 III3 III8 Ill.7 III8 III8 III7 III8 III7 III7 IIIX
03-0.4 I.1 0. I3-0.25 I.1 0.7.s 0. I3-0.25 0 I3-0.25 0.0750. I3 O.I.w.25 0.x-0.1 0.075-0. I3 0.25-0.-l 0.x-o -I I.1 0.13~0.2s I.3 I.1 0.3-0.-l
0.0 I o-0.0 IS 0.045 0.005-0.010 0 015 0.030 0.005-0.010 O.WS-0.010 O.W3-0.005 o.ws-0.010 0010-0015 O.W3-0.005 0.0 I o-o.0 IS 0.010-0015 0.045 0.005-0.010 0.050 0.0-1s 0.010-0.015
8-15 915 845 91s 91.5 845 815 I345 81.5 8-15 845 8-lS 8-15 925 Y-IS 91s 91s 845
I550 1675 I SSO 1675 lb75 I SSO IS50 ISSO I550 I550 I SSO IS.50 I SSO I7W ISSO 1675 I675 ISSO
Time, h
Quench
Subsequent treatment
Eardness, ERC
Carbon steel Adapter Arbor, tapered Bushing Die block Disk Flange Gage rings. knurled Hold-down block fnsen.tapered Lever Link Plate Plllg Plug gage Radius-cutout roll Torsion-barcap
-I 6.5 6.5 5 5 5 1 b.5 -I 5 I I 7 65 6.5 6.5 0.1’
AC 4C AC AC AC
62-63 62-63 62-63 62-63 59-6 I 56-57 55 mm(d) 62-63 62-63 62-63 (e)
(b) Oil AC AC
(e) 62-63 62-63 62-63 45-47
Resulfurized steel Bushing Dash sleeve Disk Dri\e shah Guide bushing NUI Pin Plug Rack Roller SCRW Shdi Spring seat Stop collar Stud Valve bushing Vahe retainer H’asher
2
7 ! 7 s I I 0.5 I 2 0.5 2 7 65 I 8
7 2
Oil 4c Brine AC (i) Oil Oil Oil Oil Oil Oil Oil Oil AC 011 AC (i) Oil
(C) (g) (C) (h) (C‘J (5) (C) (Cl (C) (C) (C) (CJ (a (CJ (EJ (Cj
(e) 58-63 (e) 58-63 58-63 (e) (e) (e) (CJ (e) k) (ei (CJ 60-63 (e)
58-63 58-63 W
(a)Reheatedat 79O”C( I4SO”F).quenched incauslic. tempered al lSO”C(3W “F). (brTransferred to neuualsalt al 79O”C( lXiO’F).quenched incaustic. temperedat I75 “C(350 “F). (c)Tempered at I65 “C (325 “F). (d) Or equivalent. (e) File-hard. (f) Tempered al 205 “C (-100 “F). (g) Rehealed ar 84.5 “C I I550 “F,, quenched in sall at I75 “C (350°F). (h) Reheated al 77s “C( 1125”F~,quenched in salt at l9.i “C 1380°F). ti)Tempered at lb5 “C (325 “FJ and treated at -85 “C I-120°F)
Liquid Carburizing Typical applications
Carbon Steels in Noncyanide
Weight Part Production mols Bicycle forks Shift leverand ball Clock screus and studs Flar head screfi s
(a) Partial immersion.
Baths
of carbon steels
lb
Steel
0.5-2.0 I .-I
I. I-1.1 3.1
1018 1017(a)
-1.5 O.W5 0.015
-3.3 0.0 I I 0.033
I@Mu). 1017(b) IW6. I I I3 II22
kg
(b) Carhurizer
brass braze
Case depth mm in. 0.375 0.05-0.08
O.OlS 0 0020.003
0.3 0.010 0.08-O. IO o.O03-0.001 0. I5 O.Wb
Temperature T OF
Time, h
Quench
925 93
I700 I700
0.5. I .o 0.085
Brine Brine
93 9s.i 925
I700 I750 I700
0.67 0.’ 0.33
.Aircool?Ojinbrinr Brine hlollen salt. 290 “C (550’;F1
Subsequent treatment
Eardness, ERC SO-60
Temper at 425 “C (795 “FJ
60 Fi Ie hard 62-6-l 56
138 / Heat Treater’s
Carbonitriding Typical applications
Guide
Carbon Steels and production cycles Casedepth 0.001 ill.
Steel
mm
1020 1010 1010 101s 1015 1213(h) I030 1015 1022 III7 1117 1010 1213(b) III8 1018 1030 1018 I o-lo
0.05-O. IS 0.05-o. I5 0.38-0.45 0.08-o. I3 0.15-0.25 0.30-0.38 0.15-0.25 0.05-O. I5 0.30-0.38 0.20-0.30 -0.75 0.38-0.45 0.30-0.38 0.30-0.36 0.38-0.50 0.25-0.50 0.38-0.50 0.25-0.50
Part
Furnace temperature OF OC
Total time in furnace
Quench
carboo steels Adjusting yoke, 3-S by 9.5 mm ( I by 0.37 in.) Bearing block 64 by 32 by 3.2 mm (2.5 by I .3 by 0. I3 in.) Cam. 2.3 by 57 by 6-t mm (0. I by 2.25 by 2.5 in.) cup. 13g(O.-t6oz) Distributordrive shaft I25 mm OD by I27 mm (5 by 5 in.) Gear.44.5 tntndiam by 3.2 mm( I.75 by0.125 in.) Hex nut. 60 3 by 9.5 mm (2-l by 0.37 in.) Hood-latch bracket. 6.4 mm diam (0.25 in.) Link. 2 by 38 hy 38 mm (0.079 hy I .5 by I .S in.) Mandrel.4Og(l.-ll oz) Paper-cutting tool. 410 mm long Segment,2.3by44.5by44.5mm(0.09by 1.7Shyl.7Sin.) Shaft. 1.7 mm diam by IS9 mm (0.19 by 6.25 in.) shtftcollar,59g(2.lozJ Sliding spur gear, 66.7 mm OD (3.625 in.) Spring pin. l-I.3 mm OD by I II mm CO.56by 4.S in. J Spur pinion shti II 3 mm OD ( I.625 in.) Transmission shift fork I27 by 76 mm (5 by 3 in.) (a) Modifiedcarbonitriding (g)Oilat 150°C(3W”Fk
2-6 2-6 15-18 3-5 6-10 12-15 6-10 2-6 12-1s S-12 -30 15-18 12-15 12-l-I IS-20 IO-20 IS-20 IO-20
77Sand745 775 and 745 855 790 SlSand7-tS 855 815attd715 775 and 7-U 855 8-E
I-IX and I375 lQSandl375 I575 1150 ISWand 1375 I575 15Wand 1375 l12S and I375 1575 I550
@mitt tintin 2 ‘/z h ‘/2 h I08 mm I 3/, h 64min Mmin I ‘12 h I ‘/? h
855 815 77s 870 815and715 870 815and7-15
I575 1500 1130 1600 15Wand 1375 1600 15Wand 1375
2’/: h 2 ‘h h 5t/; h 2h(n Ij-lmitt 2h(D 162min
atmosphere. (b) Leaded. (c)Tempered at 190 “C (375 “F). td) Tempered at IS0 “C (300 “P). (c)Tempered tempetedat 150°C (300°F): for I h. (h)Oilat ISO”C(3W”F): temperedat XO”Ct5W”F) for I h
Applications Substrate material AlSI BSI
for Boride Carbon Steels DtN St37
1020 1043 II38 IO42
Clfi(CklS) C-IS stso- I JSS20 Ck45
Application Bushes. bolts. nozzles. conveyer tubes. base plates. runners. blades. thread guides t3eardrives.pumpshaft.s Pins, guide rings, grinding disks. holts Casting inserts. nozzles. handles Shaft protection sleeves. mandrels Swirl elements. nozzles (for oil burners). rollers. bolts. gate plates
at 165 “C (325 OF). (f)Time
Oil Oil Oil Oil
Gas(a) oil(c) Oil Oil Oil Oil oil Gas(a)(d) Oil(e) oil(g) Oil Oil(h) Gas(a) at temperature.
Nonresulfurized (1000
Carbon
Steels
Series)
1005 Chemical Composition. AISI and UNS: 0.06 C max. 0.35 Mn mity, 0.040 Pmax. 0.050 S max; (standard steel grade for wire rod and wire only)
Recommended Case Hardening.
Heat Treating Can he carhonitrided
Practice
1006 Chemical Composition. AISI and UNS: 0.08 C max. 0.25 hln max. 0.040 Pmax, 0.050 S max; (standard steel grade for wire rod and wire only)
Recommended Case Hardening. processes
Heat Treating Carbonitriding
Practice
and liquid
carburizing
are suitable
1008 Chemical
COmpOSitiOn. AISI and UNS: 0. IO C max. 0.30 to 0.50 Mn. 0.040 P max, 0.050 S max. UNS Cl0080 and AIM-SAElOOS standard composition ranges and limits: 0.10 C max. 0.25 to 0.50 Mn
Similar Steels (U.S. and/or Foreign). UNS G 10080: ASTM A 108. A5 IO, A5 19. AS45. AS49. A575. A576; FED QQ-S-637 (C 1008). QQ-S-698(C1008); MILSPEC ML-S-I1310(CS1008): SAEJ403. J412, J414; (Ger.) DfN 1.0204: (Ital.) UNI CB IO FU Characteristics. Extremely ductile in the normalized or annealed condition and often subjected to severe cold reduction. Has excellent cold formability and is readily welded by any of the well-known welding processes. Brazing results also excellent, which accounts for widespread use of furnace brazing in producing assemblies. Machinability is extremely poor
Recommended
Diagram. Containing
0.43 Mn; austenitized at 915 “C (1680 “F). Grain site transformation temperatures are estimates.
0.06 C, size, 7. Marten-
Practice
Normalizing. Heat to 925 “C (I 695 OF). This will restore the microstructure. which consists of a few pearlite plates dispersed among grains of blocky ferrite
Annealing. When clean surfaces are required. heat to approximately 910 “C (1670 “F) in a lean exothermic atmosphere. Cool in the cooler section of a continuous furnace. Microstructure following this treatment essentially the same as that obtained after normalizing Tempering. honitriding
Although the vast majority of parts case hardened by carare not tempered. they can be rendered less brittle by tempering
1008: Carbonitriding 1008: Isothermal Transformation
Heat Treating
140 / Heat Treater’s
Guide
1008: Microstructures. (a) Aluminum-killed 1008 steel, normalized after 60% cold reduction to a final ferritic structure contains fine pearlite (dark areas) at the grain boundaries. 4% nital. 1000x. (b) Same 595 “C (1105 “F) after normalizing. Ferritic structure contains some fine pearlite and some spheroidized 4% nital. 1000x. (c) Same as (a), except process annealed at 705 “C (1300 “F) after normalizing. The mentite particles at the grain boundaries. 4% nital. 1000x
1008: Rimmed 1008 steel part, formed from sheet, with surface roughness (orange peel). Not polished, not etched. Actual size
thickness of 0.8 mm (0.03 in.). The as (a), except process annealed at cementite at the grain boundaries. ferritic structure contains some ce-
1008: Rimmed 1008 Steel Parts. Magnified cross section shows the coarse surface grain that caused the orange peel. nital. 50x
Nonresulfurized
at 150 to 205 “C (300 to 400 “F) without hardness
appreciable
loss of surface
Case Hardening. Hard. wear-resisting surfaces can be obtained on parts by carbonitriding. Depth of case developed depends upon time and temoerature. Carbonitride at 760 “C ( 1300 “F) to 870 “C ( I600 “F). Atmosphere usually comprised of an enriched carrier gas from an endothermic generator, plus about IO%, anhydrous ammonia. Case depths usually range from approximately 0.008 to 0.25 mm (0.003 to 0.010 in. ). Maximum
Carbon
Steels / 141
surface hardness usually obtained by oil quenching directly from the carbonitriding temperature. Cyanide or cyanide-free liquid salt baths and gas carburizing may also be used for equi\&nt results. Temperatures. time at temperature. and quenching practice also approximately the same
Process Annealing. Heating to 600 “C (I I IO OF) will recrystallize cold worked structures: often used as an intemrediate anneal prior to further cold working
Nonresulfurized
Carbon
Steels / 141
1010 Chemical COIIIpOSitiOn. AISI 0.60 Mn. 0.040 P max. 0.050 S max
and UNS: 0.08
to
0.13 c. 0.30 m
Annealing.
For clean surfaces. heat to approximately 9 IO “C (1670 OF) in a lean exothemic amlosphere. Cool in the cooler s&ion of a continuous furnace
Similar Steels (U.S. and/or Foreign). UNSGIOIOO; AMS 5010. 5042. 504-t. 5047. 5053: ASThl A 108. A5 IO. AS 19. A545. A519. A575 AS76; MfLSPEC MLS-11310 (CSIOIO); SAE J103. J-IIZ. J4l-l: (Ger.) DJN I.IIZI;(Fr.)AFNORXC lO;(Jap.)JISS l0C.S 12C9CK
Tempering.
Characteristics. Extremely ductile in the normalized or annealed condition and often subjected to severe cold reduction, accounting for excellent cold formability. However. as the carbon content increases the cold formability decreases, slightly reducing the severity it can withstand in cold forming. Weldability and brazing results are excellent. h,Jachinability is poor
Case Hardening. Carbonitride at 760 to 870 “C (l-t00 to 1600 “F) in an enriched endothermic carrier pas. plus about IO%, anhydrous ammonia. Case depths range from 0.076 to 0.25-l mm (0.003 to 0.01 in.). Oil quenching directly from carbonitridinp temperature pro\.ides maximum surface hardness. Salt baths produce similar results. Flame hardening, austemperinp. and liquid carburizinp are alternative processes
Recommended Normalizing.
Heat Treating
Heat to 925 “C (I695
Practice
“F). Cool in still air
Optional. Tempering at IS0 to 205 “C (300 reduces hrittleness without appreciable loss of surface hardness
IO
100 “F)
PrOCeSS Annealing. Heating to 600 “C t I I IO “F) will recrystallize cold \\orked structures: often used as an intemrediate anneal pnor to further cold working
1010: Microstructures. (a) Nital, 200x. Carbonitrided at 790 “C (1455 “F) and oil quenched, showing a high-carbon, low-nitrogen case, Core (right half of micrograph) is predominantly ferrite. (b) 29/onital, 700x. Liquid nitrided 1 h at 570 “C (1060 “F) in aerated nitriding salt bath. Nitrided layer, 0.0076 mm (0.0003 in.) deep. Core structure, blocky ferrite and grain-boundary carbide. No transition zone evident
142 / Heat Treater’s
Guide
1010: Time-Temperature Diagram. Composition: 0.12 C, 0.50 Mn. 0.16 Si, 0.004 P, 0.010 S, 0.0005 N. Austenitized for 15 min. Grain size: 9.9. Source: Atlas of Time-Temp. Diagrams for Irons and Steels
at 925 “C (1695 “F)
1010: Carbonitriding. Effect of carbonitriding temperature on dimensional stability of three 1010 steel production parts. Parts were carbonitrided to produce a case depth of 0.13 to 0.20 mm (0.005 to 0.008 in.) with minimum surface hardness of 89 HR15N. Gas ratios and dew points were essentially the same for all temperatures. Time at temperature was 15 to 45 min, depending on temperature. ID, inside diameter. Part dimensions and tolerances given in inches
Nonresulfurized
Carbon
Steels / 143
1010: Cyanide-noncyanide Treatments. Comparison of compound zone thickness produced by low-cyanide and cyanidebased treatments containing sulfur
Nonresulfurized
Carbon
Steels / 143
1012 Chemical
Composition.
AISI and UNS: 0.10 to 0.15 C. 0.30 to
Recommended
Heat Treating
Practice
0.60 Mn, 0.040 P max. 0.050 S max
Normalizing. Similar
Steels (U.S. and/or
Foreign).
A5lO. A519. A545, A539. A575 (CSlOl2): SAE J103, J412. J-II-t
AS76:
UNS
MIL
~10120: ASTM SPEC MLS-11310
Characteristics. Extremely ductile in the normalized or annealed condition and often subjected to severe cold reduction. accounting for excellent cold formability. However. as the carbon content increases the cold formability decreases, slightly reducing the severity it can withstand in cold forming. Therefore, this steel is best suited for production of stampings. where the amount of drawing is minimal. Weldability and brazing results are excellent. Machinability is poor
Heat to 925 “C t 1695 “F). Cool in still air
Annealing.
For clean surfaces. heat to approximately 885 “C f 1625 “F) in a lean exothermic atmosphere. Cool in the cooler section of a continuous furnace
Case Hardening. Carbonitride at 760 to 870 “C (1300 to 1600 “F) in an enriched endothermic carrier gas. plus about IO% anhydrous ammonia. Case depths range from 0.076 to 0.25-t mm (0.003 to 0.01 in.). Oil quenching directly from carbonitriding temperature provides maximum surface hardness. Salt baths produce simihar results. Flame hardening is an altemative process
Nonresulfurized
Carbon
Steels / 143
1013 Chemical
Composition.
AISI and UNS: 0. I I to 0.16 C. 0.50 to
0.80 Mn. 0.040 P max. 0.050 S max
Recommended Case
Hardening.
processes
Heat Treating Flame
hardening
Practice and carbonitriding
are suitable
Nonresulfurized
Carbon
Steels / 143
1015 Chemical
Composition.
AISI and UNS: 0.13 10 0.18 C. 0.30 to
Forging.
Heat to 1290 “C (2.355 “F). Do not forge below 925 “C (1695 “E)
0.60 Mn. 0.040 P max. 0.050 S max
Similar
Steels (U.S. and/or Foreign).
1.1~s
G10150:
~h1.s
5060; ASTM A5 IO. AS 19. A515 A539. A515 A576. A659: FED QQ-S698~C1015);MILSPECMIL-S-16971;SAE5~03,J~12.J~13;(Ger.)DIN I.IIJI;(Fr.)AFNORXC l5,XC lS;(Jap.)JISS 15C.S l7C.S 15CK: (Swed.) SSIJ I370
Characteristics. Sometimes considered a borderline grade of steel. Carbon content is high for best cold formability and slightly low compared with grades of carbon steel used for most carburizing apphcations. Excellent forgeability. reasonably good cold formability, and excellent weldability. Machinability is relatively poor compared with the II00 and I200 grades
Recommended Normalizing.
Heat Treating
Heat to 915 “C t I680 “F). Air cool
Annealing. Heat to 885 “C (1625 cooler or by furnace cooling Hardening.
Practice
‘F). Cool
slowly.
preferably
in a
hlav be case hardened by carburizing. (See procedure for 1020.) More often.-it is subjected to light case hardening by carbonitriding or casing in a liquid bath. (See procedure for 1008 steel.) Flame hardening, gas nitriding. and electron beam hardening are alternative processes. In many instances. forgings of this grade are used in service either as forged or as forged and normalized
144 / Heat Treater’s
Guide
1015: Maximum Case Hardness vs Carbon Content
1015: Nitriding. At 565 “C (1050 “F), using aerated bath process
1015: Liquid Carburizing. Plots of carbon concentration versus carbon penetration for 1015 steels that were carburized at 930 “C (1705 “F) for 1 h with two different Durofer process base salt regenerators 1015: Microstructure.
The metallographic appearance of AISI 1015 material after a 2-h vacuum-nitrocarburizing treatment in an ammonia/methane mixture with 1% oxygen addition
Nonresulfurized
1015: Gas Nitriding. Comparative Amsler wear tests on AISI 1015 after various ferritic nitrocarburizing treatments. 1, untreated; 2, cyanide-based salt bath nitrocarburizing with sulfur; 3, subatmospheric oxynitrocarburizing; 4, gaseous nitrocarburizing; and 5, cyanidebased salt bath nitrocarburizing (treatment 1)
Carbon
Steels / 145
1015: Liquid Nitriding. Nitrogen diffusion in AISI 1015 steel
Nonresulfurized
Carbon Steels / 145
1016 Chemical Composition. AISI 0.90 Mn, 0.040 P max. 0.050 S max
and UNS:
0. I? to 0.18 C, 0.60 to
Similar
Steels (U.S. and/or Foreign). UNS Gl0160: ASThl A 108. AS IO. A5 13. AS-15 AS-18. AS19, AS76. A659; MIL SPEC hlIL-S866; SAE J403,J412. J-l14 (Ger.) DIN I.0419
Characteristics. Carbon content is high for best cold formabilit> and slightly low compared with the grades of carbon steel used for most carburizing applications. Excellent forgeability reasonabll good cold formability and excellent weldabilit>. Machinablhty is relativeI> poor compared with the II00 and I200 grades Forging.
Heat to I290 “C (2355 “F). Do not forge below 93 “C ( 1695 “F)
Recommended Normalizing.
Heat Treating
Heat to 93
“C t 1695 “F). Air cool
Annealing. Heat to 885 “C (1625 cooler or by furnace cooling Hardening.
Practice
‘F). Cool
slowly,
preferably
in a
hln\ be case hardened b! carburiring. (See procedure for 1020.) hlore often.-it is subjected to light case hardening by a&o&riding or casing in a liquid bath. (See procedure for 1008 steel.) Flame hardening is an alternative process. In man! instances. forgings of this grade are used m serwce either as forged or as k~rgsd and normalized
Nonresulfurized
Carbon
Steels / 145
1017 Chemical Composition. AISI 0.60 Mn. 0.040 P max. 0.050 S mnx Similar
and UNS:
0. IS IO 0.X
c. 0.30
to
Steels (U.S. and/or Foreign). UNS Glol70: ASTAl A 108, ASIO. ASl3, AS 19, A544. A549. x575. A576. A659: hllL SPEC MIL-S-ll3lO(CS 1017);SAE5303.5412.5-113;Ger.)DIN I.I14I;(Fr.) AFNORXC lS,XC l&tJap.)JISS 1SC.S 17C.S liCK:(Swrd.)SS,; I370
Characteristics. Escellrnt forgeahility. reasonably good cold forrnability and excellent \~eldabilit>. As carbon content increases. strength also increases. accompanied b> ;1 small decrease in cold formability. Machinnbilit> IS relativeI> poor comparsd with the II00 and I200 grades Forging.
Heat to 1275 “C (2329 ;F). Do not forge below 910 “C (I670 “F)
146 / Heat Treater’s
Recommended Normalizing.
Guide
Heat Treating
Heat to 885 “C (I625
Annealing. Heat to 885 “C (I625 cooler or by furnace cooling Hardening.
Practice
1017 Hardness erage
OF). Air cool “F). Cool
slowly,
preferably
m a
May be cnse hardened hy carburizing. (See procedure for 1020.) More often, it is subjected to light case hardening by carbonitriding or casing in a liquid bath. (See procedure for 1008 steel.) Flame hardening is an alternative process. In many instances. forgings of this grade are used in service either as forged or as forged and normalized
based
vs Tempering
on a fully quenched
Temperature. structure
Represents an av(no case hardening)
146 / Heat Treater’s
Guide
1018 Chemical Composition. AISI and UNS: 0.15 to 0.20 C. 0.60 to 0.90 hln. 0.040 P max. 0.050 S max
Recommended
Similar
Normalizing.
Steels (U.S. and/or Foreign).
UNS
Gl0180;
AMS
5069; ASTM A 108. A5 IO. A5 13. AS 19, AS-U. A535. AS-N. A519. A576. A659: MILSPEC MIL-S-11310 (CSlOl8); SAE J103. J-II?. J-II-l
Characteristics. Excellent forgeability. reasonahly good cold formability, and excellent vveldability. As carbon content increases. strength also increases, accompanied by a small decrease in cold formability. Machinability is relatively poor compared with the I100 and 1200 grades. The slightly higher manganese (compared with 1017) provides a slight increase in strength in the nomralized or annealed condition. Higher manganese also provides for a mild increase of hardenability for case hardened parts Forging.
Heat to 1275 “C (7375 “F). Do not forge below 910 “C (1670 OFJ
Heat Treating
Practice
Heat to 925 “C (I 695 “F). Air cool
Annealing. Heat to 885 “C (I675 cooler or by furnace cooling
“F). Cool
slowly,
preferably
in a
Hardening. May be case hardened by liquid or gas carburizing, or by flame hardening. (See procedure for 1020.) Quenchants include aqueous polymers. hlore often. it is subjected to light case hardening by carbonitriding or casing in a liquid bath. (See procedure for 1008 steel.) In many instances. forgings of this grade are used in service either as forged or as forged and normalized. Grade 1018 is used to a considerable extent for carburizing to deep case depths 1018: Carburized, Oil Quenched, and Tempered. 12.7-mm (0.5in.) diam bar, carburized at 925 “C (1695 “F) for 4 l/2 h. oil quenched, and tempered at indicated temperatures
Nonresulfurized
1018: Carburizing Temperature vs Depth of Case. Treated 3 h at temperature. Endothermic gas atmosphere, enriched with natural gas. Carbon potential automatically controlled by dew point method, producing 0.90 to 0.95% surface carbon.
Carburizing Symbol
“F
%pera%!
,3.
1950
1065
0.. A
1900 1850 1800
1040 1010 980
8: : : : : : : :c%
E L
Dew point
-7 to -5 -2 to 0 +2 to +14 +6 to +9 +14 +11 to +15 +13
-22 -19 -17 -14
“C to to to to
Steels / 147
1018: Hardness vs Tempering Temperature. Decrease of surface hardness with increasing tempering temperature. Rockwell C converted from Rockwell 30-N. Carbonitrided 2 l/2 h
Symbol ‘.:I, ......................... .......................... t .......................... A...........................145
NH,. ‘2 .1550 ..155 0 .1450 0
845 845 790 790
1; 1:
-21 -18 -10 -13
-10 -12 to -10 -9
1018: Carbon, Nitrogen, and Hardness Gradients. Carbonitrided verted from Tukon
Carbon
at 845 “C (1555 “F), 4 h. Oil quenched at 55 “C (130 “F). Hardness con-
148 / Heat Treater’s
Guide
1018: Effect of Tempering Temperature on Hardness Gradients. Tempered 1 h at temperature.
Rockwell C hardness converted from dickers. (a) Carbonitrided at 790 “C (1455 “F) ,2 l/2 h; 5% NH,. (b) Carbonitrided at 790 “C (1450 “F), 2 l/2 h; 10% NH,. (c) Carbonitrided at 845 “C (1555 “F), 2 l/2 h; 5% NH,. (d) Carbonitrided at 845 “C (1555 “F), 2 l/2 h; 10% NH,
1018: EfFect of Ammonia in Carbonitriding
Gas on Hardness Gradient. (a) Carbonitrided
at 845 “C (1555 “F), 2 l/2 h. Hardness converted from Vickers
at 790 “C (1450 OF), 2 l/2 h. (b) Carbonitrided
Nonresulfurized
Carbon
Steels / 149
1018: Hardness vs Tempering Temperature. Represents an average based on a fully quenched structure (no case hardening)
1018: Microstructures. (a) 1% nital, 500x. Carburized 8 h. Surface carbon content, 0.60 to 0.70%. Ferrite (light areas), outlining prior austenite grain boundaries, and pearlite (dark areas). (b) 1% nital, 500x. Carburized 4 h. Surface carbon, 0.70 to 0.80%; wholly pearlitic. Below surface, dark areas are pearlite. Areas of ferrite outline prior austenite grain boundaries. (c) 1% nital. 500x. Carburized 6 h. Surface carbon, 0.90 to 1 .OO%. Thin film of carbide outlines pnor austenite grain boundaries in matrix of pearlite. (d) 1% nital. 500x. Carburized 16 h. Surfacecarbon, 1 .OOto 1 .lO%. Surface layer, carbide. Below surface, thin film of carbide outlines prioraustenite grain boundaries in pearlite matrix. (e) 1% nital. 500x. Carburized 18 h in continuous furnace. Cooled under atmosphere in furnace vestibule. Partly separated layer of carbide (approximately 0.90% carbon) covers pearlite matrix. (f) 1% nital, 500x. Carburized 12 h. Surface carbon. approximately 1 .lO%. Carbide surface layer. Film of carbide outlines prior austenite grain boundaries in pearlite matrix
(continued)
150 / Heat Treater’s
Guide
1018: Microstructures (continued). (g) 1% nital. 500x. Gas carburized, 5 h; 925 “C (1700 “F), pit-type furnace with air leak. Furnace cooled to 540 “C (1000 “F) in 2 h 10 min. Air cooled to room temperature. Thin decarburized layer (ferrite), caused by furnace leak, covers surface. Matrix is pearlite, with carbide at prior austenite grain boundaries. (h) 1% nital, 500x. Gas carburized, furnace cooled, and cooled to room temperature under same conditions as (g), except furnace leak was more severe. Decarburized layer (ferrite) caused by leak is thicker and covers matrix of pearlite. Carbon has diffused from grain boundaries. (j) 3% nital, 200x. Carbonitrided, 4h; 845 “C (1555 “F) in 3% ammonia. Propane, 6%; remainder, endothermic gas. Oil quenched. Cooled to -74 “C (-100 “F). Tempered 1 l/2 h at 150 “C (300 “F). Tempered martensite: some bainite. (k) Nital, 100x. Carbonitrided 4 h; 845 “C (1555 “F). Oil quenched; not tempered. Stabilized by subzero temperature. Normal case structure for carbon steel. Contains martensite, carbide particles, and small amount of retained austenite. (m) Picral, 200x. Annealed by austenitizing at 885 “C (1625 “F), 2 h. Cooled in furnace. Fully annealed structure consists of patches of pearlite (dark areas) in matrix of ferrite (light areas)
150 / Heat Treater’s
Guide
1019 Chemical
Composition. AISI I .OO Mn. 0.040 P max. 0.050 S max
Similar
Steels (U.S. and/or
and UN%
Foreign).
0.15 to 0.20 C. 0.70 to UNS
Gl0190:
ASTM
Recommended Normalizing.
Heat Treating
Practice
Heat to 935 “C i 1695 “F). Air cool
A510.A513.A519.A545.A548.A576:SAE5103.5412.5311
Characteristics.
Annealing. Heat to 885 “C (I625 cooler or by furnace cooling
Forging.
Hardening. May be case hardened by gas carburizing. (See procedure for 1020.) More often, it is subjected to light case hardening by carbonitriding or casing in a liquid bath. (See procedure for 1008 steel.) Flame hardening is an alternative process. In many instances. forgings of this grade are used in service either as forged or as forged and normalized
Excellent forgeability. reasonably good cold fomlability. and excellent weldability. As carbon content increases, strength also increases, accompanied by a small decrease in cold formability. Machinability is relatively poor compared with the I 100 and I200 grades. The slightly higher manganese (compared with IO1 8j provides a slight increase in strength and hardenability Heat to 1275 “C (2325 “F). Do not forge below 910 “C (I670 ‘F)
“F). Cool
slowly,
preferably
in a
Nonresulfurized
1019: Isothermal Transformation Diagram. Containing 0.17 C, 0.92 Mn. Austenitized at 1315 “C (2400 “F). Grain size, 0 to 2. Martensite temperatures estimated
Carbon
Steels / 151
1019: End-Quench Hardenability. 12.7 mm (0.5in.) diam bar. 0.17 C, 0.92 Mn. Grain size, 0 to 2. Austenitized at 1315 “C (2400 “F). Quenched from 870 “C (1600 “F)
1019: Hardness vs Tempering Temperature. Represents an average based on a fully quenched
structure (no case hardening)
Nonresulfurized
Carbon
Steels / 151
1020
Chemical Composition. AISI and UNS: 0.18 to 0.23 C. 0.30 to 0.60 Mn. 0.040 P max. 0.050 S max Similar
Steels (U.S. and/or
Foreign).
UNSGIOXO:
AMS ~032.
5045; ASTM ASlO. A519, A54-I. A575. A576. A659; MU SPEC MU-S11310(CS1020);SAEJ403.J412,J411:(Ger.)DIN l.O402:(Fr.)AFNOR CC 20: (Ital.) UNI C 20; (Swed.) SS1-t I-150: (U.K.) B.S. 040 A 20.070 M
20 Characteristics. Most widely used of several similar grades containing about 0.20% carbon. Available in a variety of product forms. Excellent forgeability and weldability. Even with a maximum carbon content of 0.23%. no preheating or postheating required for the vast majority of welded structures. When most of the fabricating operations consist of some form of machining. this grade is not recommended because machinability is notably poor. Widely used as a carburizing steel Forging.
Heat to 1260 “C (2300 “F). Do not forge below 900 T
( 1650
“F)
Recommended Normalizing. Annealing. Hardening.
Heat Treating
Practice
Heat to 925 “C ( I695 “F). Air cool Heat to 870 “C (1600 “F). Cool slowly,
preferably
in furnace
Can be case hardened by any one of several processes. which range from light case hardening, such as carbonitriding and the others described for grade 1008. to deeper case carburizing in gas. solid. or
liquid media. Most carburiring IS done m a gaseous mixture of methane combined with one of several carrier gases. using the temperature range of 870 to 955 “C ( 1600 to 17.50 “F). Carburize for destred case depth with a 0.90carbon potential. Case depth achieved is always a function of time and temperature. For most furnaces. a temperature of 955 “C (I 750 “F) approaches the practical maximum u ithout causing excessive deterioration in the furnace. With the advent of vacuum carburizing, temperatures up to 1095 “C (200.5 T) can be used to develop a given case depth in about one half the time required at the more conventional temperature of 925 “C (I695 “F). Alternative processes are flame hardening, boriding, liquid nitriding. and plasma (ion) carburizing
Hardening
After Carburizing
is usually
achieved
using
one of
three procedures: I. Quench directly into water or brine horn the carburizing temperature 2. After the desired carburizing cycle has been completed, decrease the furnace temperature or use lower temperature zone of a continuous furnace to 845 “C (I 5.55 “F) for a diffusion cycle. Quench in water or brine 3. Cool slowly to room temperature after carburizing. Reheat to 815 “C ( I500 OF). Quench in water or brine For rounds usually can also provide also achieve
not over 6.35 to 9.53 mm (0.35 to 0.375 in.) diam. full hardness be obtained by oil quenching. In carbonitriding, oil quenching will full hardness. The liquid carburizing method using molten salt may relatively deep cases on 1020 and similar grades of carbon steel
152 / Heat Treater’s
Guide
Tempering.
Although many carburized and hardened parts are placed in sen ice b ithout tempering, it is considered good practice to temper at I SO “C (MO “F) or somewhat higher for I h if some sacrifice in hardness can be tolerated
Recommended
Processing
1020: Influence Case Depth
l l l l l l l l
Cyanide
25.4 mm (1 in.) diam bars, cyanided
Sequence
Forge Normalize (omit for parts machined from bar stock) Rough machine and/or rough grmd Semifmish machine and grind Carburize Lower temperature for diffusion cycle Quench Temper Finish grind (removing no more than IO ?, of the effective
Concentration
case per side)
1020: Normalizing. Effect of mass and section size on cooling curves obtained in still-air at 23 “C (73 “F). 152.4 mm (6 in.) diam. Approximately 64 kg (142 lb)
30 min at 815 “C (1500 “F)
Fo
91.3 76.0 SO8 13.0 30.2 20.8 IS.1 IO.8 52
1020: Effect of Cyaniding Depth of Case
in.
mm
0.0060 0.0070 O.OMll 0.0060 0.0060 0.0055 o.wso 0.0040 0.0020
0.1574 0. I778 0.1524 0.1524 0.152-l 0. I397 0. I’70 0.1016 0.0508
Temperature
mm
ill. Produced
by immersion
0 ow25 0.00 I35 OWl75 o.w.120 Produced
by immersion
Produced
by immersion
T
I300 I400 ISW 1600
705 760 815 870
I300 I400 IS00 1600
705 760 81s 870
I 300 I-MI 1500 1600
705 760 815 870
for 30 min 0.01270 0.06350 0.10160 0.12192
O.OOIOO 0.W37.5 o.wsw 0.00600
OF
for 15 min 0 w63s 0.03129 o.ou-ls 0.08 I28
O.WO50 0.00250 mo-un 0.00480
and Time on Cyaniding temperahwe
Depth of case
1020: Gas Carburizing. Catburized
on
Depth ofcase NaCN,
l
of Sodium
for 15 min 0.03-10 0.G952.5 0. I2700 0. I5240
for 4 h in batch furnace
1020:
Effect of Cyaniding
Steel cyanided Diameter tn. IS-min
0.25 0.50 0.75 I .w 2.00 3.00
at 815 “C (1500 “F) Case depth
of specimen mm
in.
mm
6.350 I3.7Go 19.050 25.400 50.800 76.200
0.0015 0.0035 0.0030 0.0027 0.0025 0 W23
O.ll43 0.0889 0.0762 0.0686 0.0635
6.350 12.700 19.050 3.4x) SO.800 76.200
0.0045 0.0035 0.0030 0.0027 o.wx 0.0023
0. I I-13 0.0889 0.0762 0.0686 0.0635 0.0584
immersion
0.30 0 500 0 750 I .ooo 2.ooo 3 .ow 30-min
Mass on Depth of Case
0.0584
immersion
Nonresulfurized
1020: Oil Quenching. Effect of mass and section size on cooling curves in oil quenching. Oil at 37 “C (99 “F). 152.4 mm (6 in.) diam. Approximately 64 kg (142 lb)
Carbon
Steels / 153
1020: Liquid Carburizing. Effect of carburizing temperature and time at temperature on case depth and case hardness gradient. Specimens 19.05 mm (0.75 in.) diam by 50.8 mm (2 in.). Liquid carburized, air cooled, reheated in neutral salt at 845 “C (1555 “F), and quenched in salt at 180 “C (355 “F). (a) Carburized at 870 “C (1600”F).(b)900”C(1650”F).(c)925”C(1695”F)
1020: Gas Carburizing.
Variations of carbon content, 0.25 mm (0.010 in.) below the surface. Three similar batch furnaces (a, b, c) used. Twenty-five tests in each
1020: Liquid Carburizing.
Comparison of case depth and case hardness of 27 specimens, 11 .1125 mm (0.4375 in.) diam by 6.35 mm (0.25 in.). Liquid carburized, 2 h, at 855 “C (1570 “F). Brine quenched and tempered, 150 “C (300 “F)
154 / Heat Treater’s Guide
1020: Liquid Carburizing. Carbon gradients produced in low- and high-temperature shown, at (a) 845 “C (1550 “F); (b) 870 “C (1800 “F); (c) 955 “C (1750 “F)
baths. 25.4 mm (1 in.) diam bar catburized,
for time
1020: Hardness vs Tempering Temperature. Represents an average based on a fully quenched structure (no case hardening)
Nonresulfurized
1020: Liquid Carburizing. case depth. (a) 25.4 Specimen carburized 11.1125 mm (0.4375 carburized at 855 “C 150 “C (300 “F)
Effect of time and temperature on mm (1 in.) outside diam by 152.4 mm (6 in.). at temperature indicated. Oil quenched. (b) in.) diam by 6.35 mm (0.25 in.). Specimen (1570 “F), brine quenched, and tempered at
Carbon
Steels / 155
1020: Liquid Carburizing of Typical Parts. Selective carburizing by partial immersion. Only that portion to be carburfzed (shaded area) is immersed in bath. (a) Compression rod. Depth of case, 0.508 to 0.635 mm (0.020 to 0.025 in.). Hardness, 55 to 60 HRC. (b) Control linkage. Depth of case, 0.127 to 0.254 mm (0.005 to 0.010 in.). Hardness, 55 to 60 HRC. (c) Ball connecting rod. Depth of case, 0.254 to 0.381 mm (0.010 to 0.015 in.). Hardness, 55 to 60 HRC
1020: Water Quenching. Effect of mass and section size on cooling curves in water quenching. Water at 46 “C (115 “F). No agitation. 152.4 mm (6 in.) diam. Approximately 64 kg (142 lb)
1020: Liquid Carburizing. Case hardness gradients, obtained in ten tests, showing scatter from normal variations
156 / Heat Treater’s
Guide
1020: Gas Carbonitriding. Effects of ammonia concentration and inlet-gas dew point on carbon and nitrogen gradients. Carbonitrided at 845 “C (1555 “F), 4 h. Inlet gas: 5% methane; remainder, carrier gas. Air cooled. (a) 5% NH,. Dew point, -26 “C (-15 “F). (b) 5% NH,. Dew point, 0 “C (+32 “F). (c) 5% NH,. Dew point, +24 “C (+74 “F). (d) 1% NH,. Dew point, -29 “C (-20 “F). (e) 1% NH,. Dew point, 0 “C (+32 “F). (f) ) 1% NH,. Dew point, +22 “C (+72 “F)
Nonresulfurized
1020: End-Quench Hardenability: Carbonitriding and Carburizing. As-quenched hardenability measured along surface.
Carbon
Steels / 157
1020: Gas Carbonitriding. of carbonitriding
Effects of temperature and duration on depth of case. Total furnace time indicated
Inlet carbonitriding atmosphere was 5% ammonia, 5% methane, and the remainder, carrier gas. Solid line: carbonitrided 4 h at 900 “C (1650 “F). Dotted line: carburized 3 h at 925 “C (1695 “F)
1020: Plasma (Ion) Carburizing. Carbon concentration profiles in AISI 1020 steel after ion carburizing for 10, 20, 30, 60. and 120 min at 900 “C (1650 “F). Carbon profile after atmosphere carburizing for 240 min at 900 “C (1650 “F) shown for comparison
1020: Plasma (Ion) Carburizing. Carbon concentration profile in AlSl 1020 steel after ion carburizing for 10 min at 1050 “C (1920 “F) followed by vacuum diffusing for an additional 30 min at 1000 “C (1630 “F). A similar carbon concentration profile is obtained by atmosphere carburizing for 6 h at 918 “C (1685 “F)
158 / Heat Treater’s
Guide
1020: Plasma (Ion) Carburizing. Carbon concentration and hardness profiles in AISI 1020 steel after ion carburizing for 10 min at 1050 “C (1920 “F) followed by additional vacuum diffusing for 30 min at 1000 “C (1830 “F). Effective case depth is indicated by dotted line
Nonresulfurized
Carbon
Steels / 159
1020: Plasma (Ion) Carburizing. Carbon concentration and hardness profiles through cases on AISI 1020 steel after ion carburizing in methane, natural gas, and in 8:l nitrogen/propane combination. Data are based on a boost-diffuse cycle of ion carburizing for 10 min at 1050 “C (1920 “F) followed by 30 min of diffusion at 1000 “C (1830 “F)
160 / Heat Treater’s
Guide
1020: Microstructures. (a) Nital, 500x. Carbonitrided and oil quenched, showing effect of too high a carbon potential. Outer white cementite; followed by interlaced martensite needles in retained austenite. Martensite matrix on right. (b) 2% nital. 550x. Cyanided bath. 845 “C (1555 “F), for 1 h. Water quenched. As-quenched condition shows coarse martensite with some carbide particles. Free rite. (c) 2% nital 100x. Same as (b), but lower magnification; showing case, transition, and core structures. Dark impressions are Tukon microhardness indentations, 0.0762 mm (0.003 in.) apart. Equivalent hardness, 61 HRC in case and 25.5 in core
layer, in salt of fer500-g
160 / Heat Treater’s
Guide
1021 Chemical
Composition.
AK1 and UNS: 0. I8 to 0.23 C. 0.60
to
0.90 hin. 0.040 P max. 0.050 S max
Similar
Steels (U.S. and/or Foreign).
ASlO. ASl9.
l!NS Gl0210: ASThl
AS-IS. AS-W AS76. A659: SAE 1403. J-II,.
J-Ill
Tempering.
Characteristics.
Excellent forgeability and weldahilitj. Even u ith a maximum carbon content of 0.234. no preheating or postheatIng is required for the vast majority of welded structures. hlachinability is notably poor. The slightly higher manganese content pro\ ides minor increases in strength and hardenahility compared itith 1020
Forging.
Heat to 1260 “C (2300 “FL Do not forge hrlow
900 “C t 1650
“F)
some sacrifice
Heat Treating
l l l
l
Practice
l l
Heat to 925 “C (I695 “FL Air cool
l
Annealing.
Heat to 870 “C t I600 “FL Cool slam ly. preferably
in furnace
Optional. Temper at IS0 ‘C (300 “F) for I h, or higher if of hardness can be tolerated
Recommended
l
Recommended Normalizing.
Hardening. Can be case hardened by any one of several processes, which range from light case hardening (by carbonitriding and salt bath nitriding described for grade 1008) to deeper case carburizing in gas. solid. or liquid media. (See carhuriring process described for grade 109-O)
l
Processing
Sequence
Forge Normalize Rough machine Semifinish machine and grind Carburize Diffusion cycle Quench Temper Finish grind
1021: Isothermal
Transformation
Grain size, 8 to 9. Austenitized temperatures. estimated
Diagram.
0.20 C, 0.81 Mn.
at 925 “C (1695
“F). Martensite
Nonresulfurized
1021: End-Quench Hardenability. 12.7 mm (0.5 in.) diam bar. 0.17 C, 0.92 Mn. Grain size, 0 to 2. Austenitized at 1315 “C (2400 “F). Quenched from 870 “C (1600 “F)
Carbon
Steels / 161
1021: Hardness vs Tempering Temperature. Represents an average based on a fully quenched structure (no case hardening)
Nonresulfurized
Carbon
Steels / 161
1022 Recommended
Chemical
Composition. AISI and UN.9 0.18 IO 0.23 C, 0.70 to I .OOMn, 0.040 P max. 0.050 S max
AMS G10220; Similar Steels (U.S. and/or Foreign). UNS 5070; ASTM AS IO. A5 19, AS44 AS45. AS-IX. AS76: hlfL SPEC MLS11310 (CSIOZO): SAE 5403. J-117. JAI-I: (Ger.) DfN 1.1133; (Ital.) l!NI GE hln 3; (Jap.) JIS ShlnC 2 I
Characteristics. Excellent forgeabilicy and weldability. Even mith a maximum carbon content of 0.23%. no preheating or postheating is required for the vast majority of welded structures. hlachinability is notably poor. High manganese content results in increased hardenability. thus permitting achievement of full hardness by oil quenching of somewhat thicker sections than 103-O.Quenching can be less severe because ofFeater hardenability Forging.
l l l l l l l l l
Processing
Sequence
Forge Normalize Rough machine Semifinish machine and grind Carburize Diffusion cycle Quench Temper Finish grind
Heat to 1260 “C (2300 “F). Do not forge belo\{ 900 “C i 1650 “F)
Recommended Normalizing. Annealing.
Heat Treating
Practice
1022: Hardness average
Heat to 925 “C (I 69s “F). Air cool Heat to 870 “C ( I600 ‘F). Cool slow 14. prefsmbly
in furnace
Hardening. Can be case hardened by an) one of several processes. uhich range from light case hardening (by carbonitriding and salt bath nitriding described for grade 1008) to deeper case carburizing in gas. solid. or liquid media. (See carbunzinp process described for grade 1020.) Plasma (ion) carburizing is an alternative process for shallow cases. Quenchants include aqueous polymers Tempering. some sacrifice
Optional. Temper at IS0 ‘C (300 “Fj for I h. or higher if of hardness can be tolerated
based
vs Tempering on a fully quenched
Temperature. structure
Represents an (no case hardening)
162 / Heat Treater’s
1022: Gas Carburizing.
Guide
Catburized
at 920 “C (1690 “F) in 20% CO, 40% H, gas, with 1.6 and 3.6% CH, added
1022: Gas Carburizing. Carburized at 920 “C (1690 “F) with 20% CO, 40% H, gas. Contains enough H,O to produce carbon potentials indicated: (a) 0.50%; (b) 0.75%; (c) 1.10%
Nonresulfurized
Carbon
Steels / 163
1022: Cyaniding. Effect of cyaniding bath temperature on carbon and nitrogen contents and on case hardness. Specimens heat treated 1 h in 30% NaCN bath at temperatures indicated. Composition specrmens air cooled; hardness specimens, water quenched. Cyanate concentrations: 0: 4.67% at 815 “C (1500 “F); 0: 3.37% at 845 “C (1555 “F); A: 2.71% at 870 “C (1600 “F). Note: Rockwell C measurements unreliable. Thin, brittle case incapable of supporting Rockwell C load. Dip in surface hardness on Rockwell 15-N scale (0 and 0) indicative of effect of retained austenite
164 / Heat Treater’s
Guide
1022: Liquid Carburizing. Effect of time and temperature on case depth. Bars: 25.4 mm (1 in.) square by 177.8 mm (7 in.) long. Carburized at 925 “C (1695 “F). Water quenched
164 / Heat Treater’s
Guide
1023 Chemical Composition. AISI and UNS: 0.20 to 0.25 C. 0.30 to 0.60 hln. 0.040 P max. 0.050 S max Similar
Steels (U.S. and/or Foreign). l!NS G10130; ASTM AS IO. AS7S. AS76. A659 SAE J-103. J-l I?. J-l 1-I: (Grr.) DIN I I IS I ; (Fr.)
AFNOR
XC I8 S. XC 25; (Jup.) JIS S ‘0 C. S 22 C. S 20 CK
Characteristics. Quite \~rldablz. Hov,rtwr. \\ hen carbon content is in the upper end of the allouahls range. it hecomes borderline In tern15 of requiring preheating and postheating. I+ ha conlplcx structures are being welded. hlachinabilit) IS poor. Forgeahilitg IS excellent Forging.
Tempering. soms sacrifice
Normalizing.
Heat Treating
Practice
Heat to 925 ‘C t I695 “FL AU cool Heat to 870 “C (I600
l
Forg? Normalize Rough machiw Scmifini~h ~nnchi~w
l
Carbunze
l
Diffusion cycle Quench Temper Finish _gind
l l
l
Hardening.
l
which
l
Can be case hardened b) an) ow of weral procssse~. range from light case hurdcning (t-q carbonitridin_e and salt bath
Optional. Tzmper at I50 ‘C (300 ‘F) for I h, or higher if of hardness can be tolemt~d
Recommended l
Heat to I160 ‘-C (2300 “F). Do not fogs helo\\ 900 “C I 1650 “F)
Recommended Annealing.
nitriding described for grade 100X) to deeper case curbwiring in gas. solid, or liquid media. (See carburizing process described for grade 102O.j When carhorl content is near the high end of the range. the core strength of case hardened parts u ill be slight11 greater than that of IOZO
Processing
and
Sequence
grind
1023: Hardness vs Tempering Temperature. Represents an average based on a fully quenched structure (no case hardening)
Nonresulfurized
Chemical Composition. AISI 0.60 Mn. 0.040 P max. 0.050 S max Similar
and UNS: 0.21 ICI 0.z
Steels (U.S. and/or Foreign).
UNS
C, 0.30 IO
G 10250; AMS 5075.
5077; ASTM AS IO. AS 13. AS 19. AS75, A576: FED QQ-S-700 (C 1025): MlL SPEC MLS-11310 (CSlO25): I. I 158; (Jap.) JIS S25 C. S 28 C
SAE 5303. J-112. 5114; (Ger.) DIN
In aerospace practice, quenched in water
Recommended
A horderline or transition grade between case hardening and direct hardening types. It is used for both. Because of higher carbon content. it is less suitable forcold forming than 1018 and 1020. Machinability is poor. because it does not contain additives for free machining. Excellent forgeability and good weldahility. With the carbon near the higher side of the range, preheating and/or postheating may be required. depending upon the carbon equivalent and complexity of the weldtnent
Forging.
Heat to I245 “C (2275 “F). Do not forge below 900 “C ( 1650 ‘F)
Recommended
Heat Treating
Practice
Normalizing.
Heat to 925 “C (I695 “F). Cool in still air. in aerospace practice, parts are normalized at 900 “C ( I650 “F)
Annealing.
Heat to 870 “C ( I600 OF). Cool to 675 “C ( I245 OF). at a rate not to exceed 28 “C (SO ‘Fj per h. In aerospace practice, parts are annealed at 885 “C ( 1625 “F) and allowed IO cool IO below 510 “C ( 1000 “F)
Direct Hardening.
Austenitize
at 870 “C (I600
“F). Quench in water
parts are austenitized
Processing
Steels / 165
at 870 YY (I600
“F) and
Sequence
Direct Hardening l
Characteristics.
Carbon
l l l l l l l
Forge Normalize Anneal (if necessary) Rough machine Austenitize Quench Temper to desired hardness Finish machine
Case Hardening Forge Normalize l Rough machine l Semifinish machine and grind . Carburize l Diffusion cycle l Quench l Temper l Finish gnnd l
l
or brine
Tempering.
Asquenched hardness of 400 HB can be expected for sections up to approximatel) 25.4 mm (I in.j. Initial hardness can be decreased as desired. bj tempering. Water is qucnchant. Parts may be tempered at 370 “C (700 “F) for tensile strengths in the range of 630 IO 860 MPa (90 to I25 ksi) Case Hardening. Can be case hardened by any of sebernl processes. which range from light case hardening (bj carbonitriding and salt bath nitriding described for grade 1008) to deeper case carburizing in gas. solid. or liquid media. (See carburizing process described for grade 1020.) Other processes include flame hardening and plasma lion) carhurizing. Qucnchants Include water and aqueous polymers.
1025: Hardness erage
based
vs Tempering
on a fully quenched
Temperature. structure
Represents an av(no case hardening)
166 / Heat Treater’s
Guide
1025: Microstructures. (a) Picral, 500x. Normalized by austenitizing, 1095 “C (2005 “F). Air cooled. Coarse grain structure; pearlite (black areas) in ferrite matrix (white areas). (b) Picral, 500x. Normalized by austenitizing, 925 “C (1695 “F). Air cooled. Finer grain size due to lower temperature
166 / Heat Treater’s
Guide
1026 Chemical
Composition.
AISI and UNS: 0.22 to 0.78 C. 0.60 to
0.90 Mn, 0.040 P max. 0.050 S max
Similar
Steels (U.S. and/or
A273. ASIO, ASl9.
A545
Foreign).
A576; SAEJ403.
UNS Gl0260: J412. J-II-t
ASTM
Characteristics.
A borderline or transition grade between case hardening and direct hardening types. It is used for both. Because of its higher carbon content, it is less suitable for cold forming than 1018 or 1020. Machinability is poor, because it does not contain additives for free machining. Excellent forgeability, and good weldability. However. the slightly higher manganese range increases hardenability, which can be significant in welding. The tendency to weld crack increases with increasing manganese. so that preheating or postheating may have to be used. Increased hardenability will pernut through hardening of sections that are somewhat thicker when compared to 1025
Forging.
Heat to I245 “C (2275 “F). Do not forge below 900 ‘C ( I650 “F)
Case Hardening. Can be case hardened by any one of several processes, which range from light case hardening (by carbonittiding and salt bath nitriding described for grade 1008) to deeper case carburizing in gas, solid. or liquid media. (See carburizing process described for grade 1020.) Flame hardening is an alternative process
Recommended Direct Hardening l l l l l l l l
Recommended Normalizing.
Heat Treating
Practice
l
Heat to 870 “C ( I600 OFI. Cool to 675 “C ( I215 “F). at a rate not to exceed 28 “C (50 “F) per h
l
Direct Hardening.
l
Austenitize
at 870 “C (1600 “F). Quench in water
or brine
Tempering.
As-quenched hardness of 400 HB can be expected for sections up to approximately 25-i mm (I in.). Initial hardness can be decreased as desired. by tempering
Forge Normalize Anneal t if necessary) Rough machine Austenitize Quench Temper to desired hardness Finish machine
Case Hardening
Heat to 925 “C (1695 “F). Cool in still air
Annealing.
Processing
l
l l l l l
Forge Normalize Rough machine Semifinish machine and grind Carburize Diffusion cycle Quench Temper Finish grind
Sequence
Nonresulfurized
1026: Hardness vs Tempering Temperature. Specimen 3.175 mm (l/8 in.) to 6.35 mm (l/4 in.) thick. Tempering time: 0: 10 min; .:l h;A:4h;A:24h
1026: Hardness vs Tempering Temperature. Represents an average based on a fully quenched structure (direct hardening)
Carbon
Steels / 167
1026: Hardness vs Tempering Time. Textile machine forging, 304.8 mm (12 in.) long by 28.575 mm (1 l/8 in.) diam. Heated in pusher conveyor furnace, 900 “C (1650 “F). Water quenched. Tempered at 315 “C (600 “F) in muffle furnace. Both furnaces gas fired: no atmosphere control. Hardness measured on polished flash line
Nonresulfurized
Carbon Steels / 167
1029 Chemical Composition. AIM and UN!% 0.25 to 0.31 C. 0.60 to 0.90 Mn, 0.040 P max. 0.050 S max
Annealing. Heat to 870 “C ( I600 “FL Furnace cool to 650 “C ( I200 “F), at a rate not to exceed 28 “C (SO “F) per h
Similar Steels (U.S. and/or Foreign).
Hardening. Flame hardening and carbonitriding are available surface hardening processes. Austenitize at 860 “C (I 580 “F). Quench in water or brine. except for rounds under 6.35 mm (0.25 in.) diam. These may be quenched in oil for near full hardness
A273, A510, A576;SAE
UNS
G 10290;
ASThl
J303, J412
Characteristics.
With few exceptions. this grade of steel is not case hardened. May be given a wear-resisting surface by quenching from a carbonitriding atmosphere. (See procedure for 1008.) As a rule, it is used either in the normalized or annealed condition or is subjected to direct hardening and tempering. While cold formability is poor compared with lower carbon grades, grade 1029 can be purchased to specific quality requirements, which permit its use for applications that require cold estrusion or cold heading. Machinability is poor. Forgeability is excellent. Can be readily welded, but preheating and postheating are generally required for steels of this carbon content
Tempering.
Using the austenitizing practice described above. an asquenched hardness of near 425 HB should be attained. The desired hardness can then be developed by tempering
Recommended l l l
Forging.
Heat to 1245 “C (2275 “F). Do not forge below 885 “C (I625 “F)
l l
Recommended
Heat Treating
Practice
l l
Normalizing.
Heat to 915 “C ( I680 “FL Cool in still air
l
Processing
Forge Normalize Anneal (if necessary for machining) Rough machine Austenitize Quench Temper Finish machine
Sequence
166 / Heat Treater’s Guide
1029: Hardness vs Tempering Temperature. Represents an average based on a fully quenched
structure
168 / Heat Treater’s
Guide
1030 Chemical
COmpOSitiOn.
AISI and LJNS: 0.28 to 0.31 C. 0.60 to
0.90 Mn. 0.040 P max. 0.050 S max
Similar
Steels (U.S. and/or Foreign). CJNS ~10300; ASTM AS IO. AS 12. AS 19. AS-M. AS36. AS76. A682; FED QQ-S-635 CC 1030). QQ-S-7OO(ClO3Oj; MILSPEC ML-S-I l3lO(CSlO3O): SAE 5103, J112. 5114; (W. Ger.) DIN I.1 172: (Ital.) UNI CB 35 Characteristics. With few exceptions. used in the normalized or annealed condition. or subjected to direct hardening and tempering. Cold formability is poor compared M ith lower carbon grades. hlachinability IS poor. Forgeabilib is excellent. The slightly - - higher carbon content has some negative effect on weldability. Unless preheating and postheating practices are used. weld cracking may occur. Widely used for producing forgings and parts machined from hot rolled or cold drawn bars. Also available in cold heading quality for fabrication processes involving cold heading or cold extrusion
Annealing.
Heat to 870 “C ( 1600 “F). Furnace cool to 650 “C ( I200 “F) at a rate not to esceed 28 “C (SO “F) per h
Hardening. Austenitire at 860 “C t 1580 “F). Surface hardening processes include flame hardening. induction hardening. carbonitriding. and plasma (ion) carburizing. Quench in Water or brine, except for rounds under 6.35 mm (0.25 in.) diam. These ma! be quenched in oil for near full hardness Tempering.
An as-quenched tained by usmg the austenitizing be reached bj tempering
Recommended l l l
Forging.
Heat to 1215 “C (2275 “F). Do not forge below 885 “C (I625 “‘F)
l l
Recommended
Heat Treating
Practice
l l
Normalizing.
Heat to 9 IS “C ( I680 “F). Cool in still air
l
hardness of near 425 HB should be atpractice described. Desired hardness can
Processing
Sequence
Forge Normalize Anneal (if necessary for machining) Rough machine Austenitize Quench Temper Finish machine
1030: Isothermal Transformation coupons.
Austenitized
Diagram. Rolled from cast
at 905 “C (1660 “F). Grain size, 7 to 8
Nonresulfurized
1030: Hardness vs Tempering Temperature. Specimen, 9.525 to 25.4 mm (0.375 to 1 in.) thick
Carbon
Steels / 169
1030: End-Quench Hardenability. Effect of high-quenching temperature on hardness. Specimen contains 0.30 C, 0.10 Cr, 0.94 Mn, 0.012 P, 0.028 S, 0.18 Si. ASTM grain size, 1.8. Quenched at temperatures indicated
1030: Hardness vs Tempering Temperature. Specimen, 3.175 to 6.35 mm (0.125 to 0.25 in.) thick. Tempering time: 0: 10 min; 0: 1 h;&4h;A:24h
1030: Microstructures. (a) Picral, 1000x. Austenitized at 925 “C (1695 “F), 1 h; then 775 “C (1425 “F), 2 h 40 min; held at 710 “C (1310 “F), 4 h for isothermal transformation of austenite; brine quenched. Ferrite and coarse pearlite. (b) Picral, 1000x. Austenitized at 800 “C (1475 “F), 40 min; held at 705 “C (1300 “F). 15 min, for isothermal transformation; reheated to 710 “C (1310 “F), held 192 h. Partly spheroidized pearlite. Ferrite matrix
Nonresulfurized
Carbon
Steels / 169
1035 Chemical Composition. AISI 0.90 Mn. 0.040 P ma.\. 0.050 S rnzx Similar
and UNS:
0.32 to 0.38 C. 0.60 to
Steels (U.S. and/or Foreign). UNS G 10350: AhlS 5080. 5082: ASTM A.510. A.519. AS-M, AS1S. AS16. AS76. A682; FED QQ-S635 (ClO3S). QQ-S-700 (ClO.35): SAE J-103. Jll?. J-ll-k (Ger., DIN
1.0501: tFr.) AFNOR CC 35: rltnl.) UN1 C 35; (Swed.) SS1.t ISSO; (U.K., B S. 060 A 3s. (Ml A 32.080 A 35.080 A 37.080 hl 36
Characteristics.
One of the most \\ idsI\ used medium-carbon grades for mxhincry parts. A\ailnbk principally in bars or billets for forging. Escellent forgenhilit!. Special quality Lgradrs available for cold heading,
170 / Heat Treater’s
Guide
cold forging, and cold extrusion. Because of carbon content, preheating and postheating are required when welding. Interpass temperature must be controlled. Machinability is only fair. Wide range of mechanical properties can be attained by quenching and tempering
Forging.
Heat to 1245 “C (2275 “F). Do not forge below 870 “C (1600 “F)
Recommended Normalizing.
Heat Treating
Practice
Ln aerospace practice, parts are austenitized quenched in water, polymer. or oil
Tempering.
As-quenched hardness should be approximately 45 HRC. Hardness can be reduced by tempering. When quenching in water, parts may be tempered at 455 “C (850 “F) to get tensile strengths in the range of 620 to 860 MPa (90 to I25 ksi): for oil or polymer quenching, parts may be tempered at 370 “C (700 %) to get tensile strengths in the range of 620 to 860 MPa (90 to 125 ksi)
Heat to 9 I5 “C ( I680 OF). Cool in air.
In aerospace
practice.
parts are normalized
at 900 “C (I 650 “F)
Annealing. Heat to 870 “C ( 1600 “F). Furnace cool to 650 “C ( I200 “F). at a rate not to exceed 28 “C (50 “F) per h. In aerospace practice, parts are annealed at 870 “C (1600 OF) and allowed to cool below 540 “C (I000 “F)
Recommended l l l l
Hardening.
Austenitize at 855 “C (1570 “F). Flame hardening, induction hardening, austempering, liquid nitriding. and carbonitriding are suitable treatment processes. Quench in water or brine, except for rounds under 6.35 mm (0.25 in.) diam. These may be oil quenched.
1035: Normalizing. (a) Specimen, in.) diam. Approximately
1035: Water Quenching. proximately
at 845 “C (1555 “F) and
101.6-mm (4-in.) diam. Approximately
l l l l
Processing
Sequence
Forge Normalize Anneal (if necessary for machining) Rough machine Austenitize Quench Temper Finish machine
20 kg (43 lb). Still air at 20 ‘C (70 “F). (b) Specimen,
127-mm (5-
39 kg (85 lb). Still air at 25 “C (75 “F)
Specimen, 127 mm (5 in.) diam. Ap39 kg (85 lb) Water at 51 “C (125 “F). No agitation
1035: Oil Quenching. Specimen! 127 mm (5 in.) diam. Approximately 39 kg (85 lb). Oil at 32 “C (90 “F)
Nonresulfurized
1035: Hardness vs Tempering Temperature. Specimen, 31.8 to 6.35 mm (0.125 to 0.25 in.) thick. Tempered at 0: 10 min; 0: 1 h; A:4h;A:24h
Carbon
Steels / 171
1035: Hardness vs Tempering Temperature. Automotive steering arm forgings. Section thickness, 15.875 to 28.575 mm (0.625 to 1.125 in.). Fine-grained steel. Forgings austenitized at 825 “C (1520 “F) in oil-fired pusher conveyor furnace. Held 45 min. Quenched in water at 20 “C (70 “F). Tempered 45 min at 580 to 625 “C (1075 to 1160 “F) in oil-fired link-belt furnace to required hardness, 217 to 285 HB. Hardness, checked hourly with 5% sample. Readings on polished flash line of 28.575 mm (1 ,125 in.). Furnace variation at 550 “C (1120 “F) of -9 and -21 “C (+15 and -7 “F). Four mill heats and six-week period
1035: Microstructures.
(a) 1035 steel bar, austenitized 1 h at 850 “C (1560 “F), water quenched, and tempered 1 h at 175 “C (350 “F). Cross section shows light outer zone of martensite and a dark core of softer transfom-ration products 10% nital and 1% picral. Actual size (b) 10835 steel bar (same as 1035, except boron treated) after same heat treatment as bar shown in (a). Effect of boron on hardenability is evident from the greater depth of the martensite zone. 10% nital and 1% picral. Actual size (c) SAE 1035 modified (0.20% Al added) steel, salt bath nitrided 90 min at 580 “C (1075 “F) and water quenched. Surface layer of iron nitride over a matrix of ferrite and pearlite. 1% nital. 500x
172 / Heat Treater’s
Guide
1037 Chemical
Composition.
AK1 and UN!? 0.32
to
0.38 C. 0.70 IO
I .OO hln. 0.040 P max. 0.050 S max
Similar
Steels (U.S. and/or
Foreign).
UNS
Gl0370;
ASThl
A510. AS76: SAE J403. J112, Jill
Characteristics. Excellent forgeahilit). Special quality grades available for cold heading, cold forging. and cold extrusion. Because of the carbon content. preheating and postheating are required lvhen welding. Interpass temperature must he controlled. Machinability is only fair. \Vide range of mechanical properties can be attained by quenching and tempering. The higher manganese content provides additional hardenabilitj. Slightly thicker sections can he fully hardened u ith a less severe quench. compared u ith parts made from I035
Annealing. Heat to 870 ‘C I 1600 “FL Furnace cool to 650 “C ( I200 OF). at a rate not to exceed 28 “C (SO “F) per h Hardening. Austenitize at 855 “C i IS70 “F). Quench in water or brine. except for rounds under 6.325 mm (0.25 in.) diam. These may be oil quenched. Carbonitriding is a suitable surface hardening process Tempering.
As-quenched hardness should be approximately Hardness can he reduced b> tempering
Recommended l l l
Forging.
Heat to I ?-IS “C (2275 “FL Do not forge below 870 “C t I600 “F)
l l
Recommended Normalizing.
Practice
l
Heat to 9 IS “C ( I680 “F). Cool in air
l
Heat Treating
1037: Hardness vs Tempering Temperature. average
based
on a fully quenched
structure
l
Represents
an
Processing
45 HRC.
Sequence
Forge Normalize Anneal (if necessary for machining) Rough machine Austenitize Quench Temper Finish machine
1037: Water-Quenched Part. Cross section of a water-quenched SAE/AISI 1037 steel track shoe with 0.25 mm (0.010 in.) distortion caused by lightening groove. Redesigning of the shoe to remove the grooves improved uniformity of the section and reduced the distortion to a maximum of 0.08 mm (0.003 in.)
172 / Heat Treater’s
Guide
1038,1038H Chemical
Composition. 1038. AISI and UNS: 0.35 to 0.41. C. 0.60 to 0.90 Mn. 0.040 P mttx, 0.050 S max. 1038H. UNS H10380 and SAE/AISI 1038H: 0.34 to 0.43 C. 0.50 to 1.00 Mn. 0.15 to 35 Si
Similar
Steels (U.S. and/or
Foreign).
1038.
CJNS
G 10380:
ASThl ASIO. AS-U. AS-IS. A.546. AS76: SAE J403. J-II?. J-II-I; (Ger.) DIN I.1 176: (Fr.) AFNOR XC 38TS. 1038H. l!NS Hl0380; SAE Jl268: (Ger.) DIN I I 176: (Fr.) AFNOR XC 38 TS
Characteristics.
One of the most widely used carbon steels ha\ ing ;1 medium-carbon content. Most widely used for producing forgings to he used in the heat treated condition. Also available as an H steel. Welded only with the precautions used for welding of any medium-c&on steel: przheating, postheating, and control of interpass temperature
Forging.
Annealing. Heat to 855 “C ( Is70 ‘F). Furnace cool to 650 “C ( 1100 9% at a rate not to exceed 28 “C (SO “F) per h Hardening. Heat to 855 “C (IS70 “F). Carbonitriding is a suitable surface hardening process. Quench in water or brine. Rounds under 6.35 mm (0.15 in.) diam ma! bs oil quenched for titll hardness
Recommended l l l l
Heat to I215 “C (7275 OF). Do not forge below 870 ‘C t I600 “F)
Practice
l
Heat to 900 “C (,I650 “FL Cool in air
l
Recommended Normalizing.
l
Heat Treating
l
Processing
Forge Normalize Anneal (if necessary for machiningj Rough machine Austenitize Quench Temper Finish machine
Sequence
Nonresulfurized
1038H: End-Quench Hardenability. Normalized at 870 “C (1600 “F). Austenitized Distance frum quenched surface ‘/l6h mm I
1.s 2 2.5 3 3.5 -I 1.5 5 5.5
1.58
2.37 3.16 3.95 4.74 5.58 6.32 7.11 7.90 8.69
Eardness, ARC max miu 58 56 55 53 49 13 37 33 30 29
51 i2 31 29 26 24 23 21 22 21
Distance From quenched surface ‘/I,5m. mm 6 65 7 7.5 8 9 IO I2 1-l 16
9.48 IO.27 Il.06 I I X5 12.64 l-l.22 IS.80 18.96 22.12 25.x3
Carbon
Steels / 173
at 845 “C (1550 “F)
Hardness. ERC max miu 28 27 27 26 26 2s 25 2-l 23 21
?I 20 :::
‘1: .., .,.
1038: Cooling Curve. 0.38 C. 0.70 Mn, 0.015 P, 0.030 S 0.25 Si, 0.063 Al, 0.003 N. Austenitized 1095 “C (2005 “F). Grain size, ASTM 5. Solid coolina curves are for bars of indicated diameters. M, is 225 “C (435 “F); M, is 400 “C (750 “F);Ac, is 710 “C (1310 “F); AC, is 760 “C (1400°F) ”
1
174 / Heat Treater’s
Guide
1038: Cooling Curve. Austenitized at 870 “C (1600 “F). Grain size, ASTM 8. Solid cooling curves are for bars of indicated diameters. numbers are hardness, HV. Bold face numbers, ASTM grain size
italic
1038: Hardness vs Tempering Temperature. Quenched specimen, 3.175 to 6.35 mm (0.125 to 0.25 in.). Tempered
1038: Microstructures.
1h
(a) 2% nital, 50x. Longitudinal section, as forged. Secondary pipe from original bar stock (black areas). Pearlite (gray). Ferrite (white). (b) 2% nital. 100x. Transverse section, as forged. Severely overheated, showing first stage of burning. Ferrite (white) outlines prior coarse austenite grains. Matrix of ferrite (white) and pearfite (black). (c) 2% nital, 550x. Same as (b), at higher magnification. Massive ferrite outlines coarse austenite grains. Contains particles of oxide (black dots). Matrix of ferrite (white) and pearlite (black)
Nonresulfurized
1038H: Hardenability Curves. Heat-treating (1600 “F). Austenitize:
Hardness Purposes I distance, mm 1.5 3 5 7 9 II 13 I5 !O 15 3s
845 “C (1550 “F)
Limits for Specification Eardncss,EIRC Minimum Maximum S8 56 49 33 29 27 26 25 24 22
51 37 25 22 20
Hardness Limits for Specification Purposes I distance, /I6 in. I 1.5 !.5 i.5 1.5 i.5 5.5 1.5
Aardoess. EIRC Minimum Maximum 58 56 55 53 39 43 37 33 30 29 28 27 27 26 26 ‘5 ‘5 24 23 21
51 42 3-l 29 26 24 23 ‘2 22 71 21 20
temperatures
recommended
Carbon
by SAE. Normalize (for forged or rolled specimens
Steels / 175
only): 870 “C
176 / Heat Treater’s
Guide
1039 Chemical
Composition.
AISI and UNS: 0.37 to 0.44 C. 0.70 to
I .OO hln. OWO P max. 0.050 S max
Similar
Steels (U.S. and/or
Foreign).
UNS
G 10390;
ASTM
ASIO. 4516. AS76; SAE J103. J-II?. J-II-I: (Ger.) DIN I.1 157: (Fr.) AFNOR 35 M 5; (U.K.) B.S. 120 h,l36. IS0 M 36. CDS lOS/lO6
Characteristics. hledium-carbon steel. Widzl~ used for forgings that will be heat treated. Machinability is onl! fair. Since ueldability is poor, the best preheating and postheating practice is required when welding is in~olvcd. The slightly higher manganese cont2nt off2rs thz possibility of slightly increased hardenability. compared hith IO-IO Forging.
Heat to I I-15 YY (2175 ‘F). Do not forg2 b2lou 900 “C ( 1650 “F)
Recommended Normalizing.
Heat Treating
Practice
Hrat to 900 “C (I 650 “F). Cool in au
Annealing.
Tempering
After Hardening. As-quenched hardness mateI) 5?. HRC. Hardness can be reduced by tempering
Tempering After Normalizing. For large sections, normalize by comentional practice. Resuhs in a structure of fine pearlite. A tempering treatment up to about 510 “C (I000 “FJ is then applied. Mechanical properties not equal to those achie\,ed by quenching and tempering. Resulting strength is far higher than that of annealed structure. Normalizing and tcmpcring oftsn applied to hea\> forgings
Recommended
Processing
Sequence
Forgings l l l
Heat to 8-0 “C (I 55s “F). Furnace cool to 650 “C ( I200 “F). at a rate not to exceed 3 “C (50 “F) per hour
l
Hardening.
l
Heat to 815 &C t IS55 “F). Carbonitriding is a suitablz stufacc trzating process. Quench in eater or brin2. Rounds less than 6.35 mm to.75 in.) diam may be oil quenched to full hardness
of approxi-
l
l l
Forge Normalize Anneal (ifnecessarj Rough machine Awtenitize Quench Tempzr Finish machine
J or
telllper
(optional)
1039: Hardness vs Tempering Temperature. erage based on a fully quenched structure
Represents
an av-
1039: Microstructures. (a) 1% nital, 750x. Gas carburized roller for use in contact fatigue tests. Inclusions and “butterfly” alterations at center, about 0.127 mm (0.005 in.) from contact surface. Alterations believed to be work-hardened ferrite, caused by breakdown of martensite. (b) 2% picral, 1950x. Same as (a), but enlarged in electron micrograph of two-stage, carbon-chromium-shadowed replica. Lighter etching than (a). “Butterfly” alterations, formed at inclusions are believed to be oriented in direction of principal stress
Nonresulfurized
Carbon
Steels / 177
1040 Chemical
Composition.
AI.9 and UNS: 0.37 to 0.44 C, 0.60 LO
0.90 Mn. 0.040 P max. 0.050 S rnxx
Similar
Steels (U.S. and/or Foreign). ASTM ~5 IO. A5 19. AS16, A576, A681; MILSPEC MLL-S-I~~~~(CS~O-~~J; SAEJ103. J-II?. J-tl4; fCier.1 DfN 1.1186; (Jap.) JIS S 4OC; (U.K.) B.S. 080 A-IO.? S. 93 Characteristics.
Medium-carbon steel. Widely used for forgings that will be heat treated. Machinability is only fair. Since weldability is poor. the hest preheating and postheating practice is requtred when nelding is involved
Forging.
Heat to 1235 “C (2275 OF). Do not forge below 870 “C ( 1600 OF)
Recommended Normalizing.
Heat Treating
Heat to 900 “C ( I650 OF). Cool in air
After Normalizing. For large sections. normalize by comentional practice. This results in a structure of line pearlite. A tempering treatment up IO about 510 ‘C ( IO00 “F) is then applied. Mechanical properties not equal to those achieved b> quenching and tempering. Resulting strength is far higher than that of annealed structure. Normalizing and tempering often applied to heavy forgings
Recommended
l
Hardening. Heat to 845 ‘C ( IS55 “F). Flame hardening carbonitriding. and liquid carburizinp are suitable surface hardening processes. Quench in water or brine. Rounds less than 6.35 mm (I/-l in.) diam may he oil quenched for full hardness 0.39%
C - 0.72%
Mn - 0.23%
S. Grain size: 7-8
Processing
l l l l l l
Forge Normalize Anneal tif necessa@ Rough machine Austenitize Quench Temper Finish machine
Sequence
Si - 0.010%
P -
or temper (optional)
1040: Hardness Specimen, 63.5 thick. Quenched
vs Tempering to 92.075 Tempwng
2”” I
1040: Hardness vs Tempering Temperature. Specimen, to 6.35 mm (0.125 to 0.25 in.) thick. Quenched.
of approxi-
Tempering
l
Heat to 835 “C ( IS55 JF). Furnace cool to 650 “C ( I X0 “F). at a rate not to exceed 78 “C (SO “F) per h
1040: CCT Diagram. Composition:
After Hardening. As-quenched hardness mately 52 HRC. Hardness can be reduced hy tempering
Forgings
Practice
Annealing.
0.018%
Tempering
3.175
Legend: 0: 10
Temperature.
mm (2.50
remwrarure 400 I
to 3.62
in.)
C 500 I
1040: Hardness vs Tempering Temperature.
600 I
Normalized
at
870 “C (1600 “F). Oil quenched from 845 “C (1555 “F). Tempered at 56 “C (100 “F) intervals,
13.716
mm (0.54 in.) rounds.
12.827 mm (0.505 in.) rounds. Source: Republic Steel
Tested
in
178 / Heat Treater’s
Guide
1040: Normalizing. (a) Specimen, 177.8 mm (7 in.) diam. Approximately 105 kg (230 lb). Still air at 22 “C (72 “F). (b) Specimen, 209.55 mm (8.25 in.) diam. Approximately 185 kg (410 lb). Air at 35 to 24 “C (94 to 74 “F). (c) Specimen, 266.7 mm (10.50 in.) diam. Approximately 335 kg (735 lb). Air at 22 “C (72 “F)
1040: Oil Quenching.
(a) Specimen, 177.8 mm (7 in.) diam. Approximately 105 kg (230 lb). Oil at 31 “C (88°F). (b) Specimen, 209.55 mm (8.25 in.) diam. Approximately 185 kg (410 lb). Oil at 50 “C (120 “F). (c) Specimen, 266.7 mm (10.50 in.) diam. Approximately 335 kg (735 lb). Oil at 30 “C (85 “F)
Nonresulfurized
1040: Estimating Jominy Equivalent Hardenabilii. Method forestimating Jominy equivalent cooling rates (J,) in gears of specific size and configuration. Gears made from shallow hardening (1040) steel. Hardened in production. Hardness measured at various depths below surface at pitch line and mot locations. Compared with hardnesses at various (J,) distances on end-quenched bar made from same 1040 bar and quenched from same austenitizing conditions
Carbon Steels / 179
1040: Flame Hardening of Wear Blocks. Clean blocks of scale and rust, preferably by sand or shot blasting. Load blocks on conveyor. Flame head has two rows of number 54 drill size 1.397 mm (0.055 in.) flame holes. 24 of 49 holes are plugged. 152.4 mm (6 in.) between centers of end holes. Head also contains single row of water-quench holes. Head set at 15.875 mm (0.625 in.) total gap. Cone point clearance of flame. 4.763 mm (0.19 in.). Gas pressure: acetylene, 82.738 kPa (12 psi); oxygen, 151.686 kPa (22 psi). Conveyor speed, 148.08 mm (5.83 in.). Total flame hardening time, 1.5 min per pad. Hardness, 53 to 58 HRC. Total depth of hardening to core, 3.97 mm (0.16 in.)
1040: Water Quenching. (a) Specimen, 177.8 mm (7 in.) diam. Approximately 105 kg (230 lb). Water at 57 “C (135 “F). No agitation. (b) Specimen, 209.55 mm (8.25 in.) diam. Approximately 185 kg (410 lb). Water at 55 “C (130 “F). No agitation. (c) Specimen, 266.7 mm (10.50 in.)diam. Approximately 335 kg (735 lb). Water at 50 “C (120 “F). No agitation
180 / Heat Treater’s
Guide
1040: Hardness vs Tempering. Effect of mass: when normalized at 870 “C (1600 “F); oil quenched from 845 “C (1555 “F); tempered at 540 “C (1000 “F). Tested in 12.827 mm (0.505 in.) rounds. Test from 38.1 mm (1.5 in.) diam bars and over, at half-radius position. Source: Republic Steel
1040: Microstructures.
1040: Hardness vs Tempering. Effect of mass: when normalized at 870 “C (1600 “F); oil quenched from 845 “C (1555 “F); tempered at 650 “C (1200 “F). Tested in 12.827 mm (0.505 in.) rounds. Test from 38.1 mm (1.5 in.) diam bars and over, at half-radius position. Source: Republic Steel
(a) Nital 200x. 25.4 mm (1 in.) diam bar. Austenitized at 915 “C (1680 OF), 30 min. Cooled slowly in furnace. Ferrite (white areas) and pearlite (dark). (b) Nital. 500x. Same as (a), at higher magnification. Pearlite and ferrite grains more clearly resolved. Wide difference in grain size in (a) and (b). (c) Picral, 1000x. Austenitized at 800 “C (1475 “F), 40 mm. Held at 705 “C (1300 “F), 6 h, for isothemal transformation. Structure is spheroidized carbide in ferrite matrix. (d) Nital, 500x. 25.4 mm (1 in.) diam bar. Austenitized at 915 “C (1680 “F). Quenched 30 min in salt bath at 420 “C (785 “F). Air cooled. Abnormal amount of ferrite (white) indicates partial decarburization at surface (top). (e) Nital. 500x. Same as (d). Interior of bar. White areas are ferrite, outlining prioraustenite grains. Black and gray are pearlite. (9 Nital, 500x. 25.4 mm (1 in.) diam bar. Austenitized at 915 “C (1680 “F). 30 min. Oil quenched. Tempered at 205 “C (400 “F). Tempered martensite (gray); ferrite (white)
Nonresulfurized
Carbon
Steels / 181
1040: Microstructure. rite-pearlite 500x
Effect Of prior microstructure on spheroidking 1040: MiCrOStrUCtUreS. microstructure (as-quenched). (b) Starting from a ferrite-pearlite 1000x
SitiC
a 1040
steel
microstructure
A fully annealed 1040 steel showing a fermicrostructure. Etched in 4% picral plus 2% nital.
at 700 “C (1290 “F) for 21 h. (a) Starting from a marten(fully annealed). Etched in 4% picral plus 2% nital.
Nonresulfurized
Carbon
Steels / 181
1042 Chemical COInpOSitiOn. AK1 0.90 hln. 0.040 P max. 0.050 S max
and UNS:
0.40 to 0.17 C. 0.60 to
Similar
~273. AS IO. Steels (U.S. and/or Foreign). ASTM A576;FEDQQ-S-635tC1042).SAE5403.5312. J-iI-t:tGer.)DIN I.1 191: (Fr.) AFNOR XC 42. XC -!2 TS. XC -IS. XC 38; (Jap.) JIS S -15 C. S 48 C; tSwed.) SS1.t 1672
Characteristics. Machinability is only fair. Weldahilitj is poor. The best preheating and postheating practice is required when welding is involved. As-quenched hardness can be slightI> higher than 1040 Forging.
Heat to 1%
Recommended Normalizing.
“C (2275 “F). Do not forge below 870 “C t 1600 ‘F)
Heat Treating
Practice
Heat to 900 ‘C t 1650 “F). Cool in air
Annealing. Heat to 815 “C t IS55 “F). Furnace cool to 650°C t 1200°F). at a rate not to exceed 28 “C (SO “F) per h Hardening. Heat to 845 “C t IS55 “F). Flame hardening. induction hardening. horiding. and carhonitriding are suitable surface hardening processes. Quench in water or brine. Rounds less than 6.35 mm (0.25 in.) diam ma) be oil quenched for full hardness Tempering
After Hardening.
As-quenched
hardness
can be re-
duced as desired b) tempenng
Tempering
After Normalizing. For large sections. normalize by conventional practice. This results in a structure of fine pearlite. A tempermg treatment up IO about S-IO ‘C t 1000 “F) is applied. Mechanical properties not equal to those achieved ly quenching and tempering. Resulting
182 / Heat Treater’s
Guide
strength is far higher than that of annealed tempering often applied to heavy forgings
Recommended
Processing
Forgings
structure.
Sequence
Normalizing
and
l l l l l l
l
Forge
1042: Change in AC, Temperature
l
Normalize Anneal (if necessary) Rough machine Austenitize Quench Temper Finish machine
or temper (optional)
1042: Hardness vs Tempering Temperature. Tempered at 205 to 705 “C (400 to 1300 “F), 10 min to 24 h. Quenched specimen, 3.175 to 6.35 mm (0.125 to 0.25 in.). Legend: 0: 10 min; 0: 1 h; A: 4h:&24h
1042: Induction Process. Effect of prior structure and rate of heating on AC, transformation
temperature
of 1042 steel
182 / Heat Treater’s Guide
1043 Chemical Composition.
AISI and UNS: 0.40 to 0.47 C. 0.70 to
I .OO Mn, 0.040 P max. 0.050 S max
Similar Steels (U.S. and/or Foreign). UNS GlO430: ASTM A510. A576; SAJZ J403, J412.5414; (Ger.) DIN 1.0503; (Fr.) AFNOR CC 45: (Ital.) UNI C 45; (Swed.) SSt4 1650: (U.K.) B.S. 060 A-17.080 H 46. 080 M 40,080 M 46
Characteristics. Machinability is only fair. Weldability is poor. The best preheating and postheating practice is required when welding is involved. Added manganese provides increased hardenability. compared with 10-E Forging.
Heat to I245 “C (2275 “F). Do not forge below 870 “C ( 1600 “F’)
Nonresulfurized Recommended Heat Treating Practice Normalizing. Heat to 900 “C ( 1650 “F). Cool in air Annealing. Heat to 845 “C (1555 “F). Furnace cool to
ties not equal to those achieved by quenching and tempering. Resulting strength is far higher than that of annealed StrucNre. Normalizing and tempering often applied to heavy forgings 650 “C (I 200 “F).
at a rate not to exceed 28 “C (50 “F) per h
Hardening. Heat to 845 “C (I 555 “F). Flame hardening, boriding. and carbonitriding are suitable surface hardening processes. Quench in water, brine, or aqueous polymers. Rounds less than 6.35 mm (0.25 in.) diam may be oil quenched for full hardness Tempering After Hardening.
As-quenched
hardness
can be re-
duced by tempering
Tempering After Normalizing.
Carbon Steals / 183
For large sections, normalize by of tine pearlite. A temperconventional practice. This results in a SullCNre ing treatment up to about 540 “C (I 000 “F) is applied. Mechanical proper-
Recommended
Processing
Sequence
Forgings l
Forge
l
Normalize
l
Anneal (if necessary) Rough machine Austenitize Quench Temper Finish machine
l l l l l
or temper (optional)
1043: Hardness vs Tempering Temperature. average based on a fully quenched
structure
Represents
an
Nonresulfurized
Carbon Steels / 183
1044 Chemical Composition. AISI and UNS: 0.43 to 0.50 C. 0.30 to 0.60 Mn. 0.040 P max. 0.050 S max Similar Steels (U.S. and/or Foreign). A510, A575. A576;SAE
UNS
~104.40;
ASTM
J403. J412.J414
achieved by quenching and tempering. Resulting strength is far higher than that of annealed structure. Nomralizing and tempering often applied to heavy forgings
Recommended
Processing
Sequence
Characteristics.
Low-manganese version of widely used mediumcarbon 1045. Often selected in preference to 1045 for surface hardening by flame or induction, because lower manganese decreases hardenability and susceptibility to quench cracking. Excellent forgeability. Fair machinability. Responds readily to heat treatment. As-quenched hardness of at least 55 HRC. Slightly higher, when carbon is near high side of the allowable range. Used extensively for parts that will be furnace heated or heated by induction prior to quenching
Forging.
Heat to 1245 “C (2275 “F). Do not forge below 870 “C (1600 “F)
l l
l
l l l l l
Recommended Normalizing. Heat Annealing. Heat to
Heat Treating
Practice
to 900 “C ( I650 “F). Cool in air
845 “C ( 1555 “F). Furnace cool to 650 “C (I 200 “F), at a rate not to exceed 28 “C (50 “F) per h
Hardening. Austenitize at 845 “C (I 555 “E). Flame hardening, induction hardening, and carbonitriding are suitable surface hardening processes. Quench in water or brine. Rounds less than 6.35 mm (0.25 in.) diam may be oil quenched for full hardness Tempering After Hardening. erly austenitized
and quenched.
Hardness of at least 55 HRC if propHardness can be adjusted by tempering
Tempering After Normalizing.
Forge or machine (bars) Normalize (if forged. Not required for parts machined from hot rolled or cold drawn bars) Anneal (if necessary. Bar stock usually received in condition for best machining) Rough machine (forgings) Austenitize (parts from bars or forgings) Quench Temper Finish machine
Often normalized and tempered, as for 1040. For large sections, normalize by conventional practice. This results in a structure of tine pearlite. A tempering treatment up to about 540 “C (1000 “F) is then applied. Mechanical properties not equal to those
1044: Hardness vs Tempering Temperature. average based on a fully quenched structure
Represents
an
184 / Heat Treater’s
Guide
1045,1045H Chemical Composition. 1045. AK1 and UNS: 0.13 to 0.50 C. 0.60 to 0.90 hln. O.O-lO P max. 0.050 S max. 1045H. UNS H10-150 and SAE/AISI 104-W: 0.42 to 0.5 I C. 0.50 to 1.00 Mn. 0. I5 to 0.35 Si Similar
Steels (U.S. and/or
Foreign).
1045.
UNS
GlO4SO;
ASTM ASIO. ASl9. AS76. A682: FED QQ-S-635 (ClO-!5). QQ-S-700 (ClO-l5):SAEJ~03.J1I2.J-lII:~Ger.)DIN 1.119l;(Fr.)AFNORXC-l7. XC -12 TS. XC -IS, XC 48; (Jap.) JIS S 35 C. S -I8 C; (Stved.) SSt4 1672. 1045H. UNS HIO-ISO: SAE Jl268; (Ger.) DIN 1.1191: (Fr.) AFNOR XC -12. XC-lI!TS,XC-% XC18:(Jap.)JIS S15C.S18C:(S\ved,jSS14 I673
Characteristics. Most often specified medium-c&on steel. Also available as special quality grades ofproprietary steel compositions. Available in a barieb of product forms. mainly as stock for forging. Excellent forgeability. Fair machinabilit). Responds readily to heat treatment. Available as an H grade. As-quenched hardness of at least 55 HRC. Sli8htl> hipher. when carbon is near high side of the allowable range. llsed extensively for parts to he furnace heated or heated by induction prior to quenching Forging.
Heat to 17-15 “C (1375 “F). Do not forge beIon 870 “C ( 1600 “F,
Recommended Normalizing.
Heat Treating
Practice
Heat to 900 “C ( 1650 “FL Cool in air
Annealing.
Heat to 8-15 “C ( I555 ‘F). Furnace cool to 650 ‘C (I ZOO “F), at a rate not to exceed 38 “C (50 “Fj per h
Hardening. Austenitize at 845 “C t IS55 “F). Flame hardening. mduction hardening. liquid nitriding. carbonitidine, martempering. and electron beam hardening are suitable surface hardening processes. Quench in eater or brine. Rounds under 6.35 mm (0.7S in.) diam may be oil quenched for full hardness. Other quenchants include aqueous polymers
for 630 to 860 hlPa (90 to 125 ksi); -I?_5 “C (795 ‘Fj for 860 to 1035 MPa (125 to I50 ksi)
Tempering
After Normalizing. Normalize and temper as for IO-IO. For large sections, normalize b> conventional practice. This results in a structure of fine pearlite. A tempering treatment up to about 540 “C (1000 “F) is then applied. Mechanical properties not equal to those achieved hy quenching and tempering. Resulting strength is far higher than that of annealed structure. Normalizing and tempering often applied to heavy forgmgs
Recommended l l
l
l l l l l
Processing
Sequence
Forge or machine (bars) Normalize (if forged. Not required for parts machined from hot rolled or cold drawn bars) Anneal (if necessary. Bar stock usualI> received in condition for best machining) Rough machine (forgings) Austenitize (parts from bars or forgings) Quench Temper Finish machine
1045: Mass and Section Size vs Cooling Rate in Oil. Specimen: 101.6 mm (4 in.) diam; at 35 “C (94 “F)
approx.
20 kg (43 lb). Oil quenched
Tempering
After Hardening. Hardness of at least SS HRC. ifproperly austenitized and quenched. Hardness can be adjusted by tempering. IVhen quenching in water. parts may be tempered at a range of temperatures to get specific ranges in tensile strength: 565 “C (I050 “F) for 670 to 860 hlPa (90 to I25 ksi); -I80 ‘C (895 OF) for 860 to 1035 hlPa (I 75 to IS0 ksi): 370 “C (700 ‘Fj for 1035 to II75 MPa (150 to 170 ksi). when quenching in oil or polymer. parts may be tempered at: 510 “C ( 1000 “F) 1045: Cooling Rates in Quenching. ums on cooling rates. mm (4 in.). Quenched centers of specimens
Effect of quenching mediCylinders, 25.4 mm (1 in.) diam by 101.6 in salt, water, and oil. Thermocouples at
1045: Induction Hardening. Effect of heating time on depth of hardening. Tendency toward cracking of machined and ground spectmens. Specimens, 25.4 mm (1 in.) diam, with a 50 kw, 450 000 cycle generator. Water quenched. Hardness, 61 to 63 HRC
Nonresulfurized
1045: Isothermal Transformation
Diagram. Composition:
Carbon
Steels / 185
0.45 C, 0.67 Mn, 0.26 Si, 0.06 Ni, 0.009 Mn, 0.009 P, 0.012 S
1045: Mass and Section Size vs Cooling Rate in Water. Speci-
1045: Hardness vs Tempering Temperature, Specimen, 3.175
men: 101.6 mm (4 in.) diam; approximately quenching at 46 “C (115 “F). No agitation
to 6.35 mm (0.125 to 0.25 in.) thick. Quenched. min; 0: 1 h; A: 4 h; A: 24 h
20 kg (43 lb). Water
Legend: 0: 10
188 / Heat Treater’s
Guide
1045: Cooling Rates in Martempering.
Effects of section size and agitation of quench bath on time required for centers of steel bars to reach martempering temperature. Quenching bath is a neutral chloride bath at 845 “C (1550 “F), into anhydrous nitrate - nitrate martempering salt at: (a) ; 205 “C (400 “F); (b) 260 “C (500 “F); (c) 315 “C (600 “F). Length of each bar, 3x diam
1045: Hardness Distribution
in Water-Quenched Bars
1045: Variations in Hardness After Production
Tempering.
Plate sections, 19.05 to 22.23 mm (0.75 to 0.875 in.) thick. Water quenched to hardness range of 534 to 653 HB. Tempered at 475 “C (890 “F) for 1 h in continuous roller hearth furnaces. Data represent two-month production period
Nonresulfurized
1045: Hardness Distribution
in Oil-Quenched
Bars
Carbon
Steels / 187
1045: Induction Hardening. Efficiency of energy transfer at several frequencies. Bars of various sizes heated to 1095 “C (2005 “F). Inside diam of inductors, 28.575 mm (1.125 in.) larger than outside diam of bars
1045: Hardness vs Tempering Temperature. Effect of time at tempering temperature on Brinell hardness of four handgun frame forgings, 101.6 mm (4 in.) by 152.4 mm (6 in.) by 19.05 mm (3/d in.). Heated at 845 “C (1555 “F) in pusher conveyor furnace. Oil quenched. Tempered at 545 “C (1000 “F) in muffle furnace. Both furnaces gas fired, without temperature control. Hardness measured after removal of 0.635 mm (0.025 in.) of material by grinding. 20 heats
1045: Hardness vs Tempering Temperature. Specimen, 38.1 to 63.5 mm (1.5 to 2.5 in.) thick. Quenched
1045: Variations in Hardness After Production
Tempering.
Forged woodworking cutting tools. Section of cutting lip hardened locally by gas burners that heated steel to 815 “C (1500 “F). Oil quenched and tempered at 305 to 325 “C (585 to 615 “F), 10 min, in electrically heated, recirculating-air furnace to desired hardness, 42 to 48 HRC. Data recorded for g-month period and represent forgings from 12 mill heats
188 / Heat Treater’s
Guide
1045: Laser Hardening of Steel Gear
1045H: End-Quench Hardenability Distauce fmm quenched surface ‘/lb in. mm
Eardness, ERC max min
I
IS8
I .s 2
2.31 3.16
62 61 59
55 52 -I2
2.5 3
3.95 4.71 5.53 6.32
56 52 46 38
31 31 29 28
7.1 I 7.90 8.69 9.18 10.27
3-l 33 32 32 31
27 26 26 2s 25
3.5
1 4.5 5
5.5 6 6.5
Distance 6-um quenched surface L/lain. mm 7 7.5 8
Eardness. ERC max mill
II.06 11.85 12.61
31 30 30
9 IO I2 I-l
13.22 15.80 18.96 22.12
29 29 28 27
I6 18 20 22 7-l
X.28 28.4-I 31.60 34.76 37.92
26 25 23 22 21
Nonresulfurized
1045H: Hardenability
Curves. Heat-treating
870 “C (1600 “F). Austenitize:
Hardness Purposes I distance, nm 1.5 5 3 II I.7 IS !O !5 IO
iardness Purposes I distance, /If, in. .5 !.5 1.5 1.5
is i.5
‘3 1
0 2 -I 6 8 10 !2 ‘!-I
temperatures 845 “C (1550 “F)
Limits for Specification Hardness, ERC hlinimum Maximum 62 60 53 36 32 31 30 29 28 27
55 15 31 27 25 24 23 22 20
Limits for Specification Eardoess, HRC hlinimum Maximum 62 61 59 56 52 46 38 3-l 33 32 32 31 31 30 30 29 29 28 27 26 25 23 21 21
55 52 32 34 31 29 28 27 26 26 2s 25 25 2-l 24 23 2’ 21 ‘0
recommended
Carbon
by SAE. Normalize (for forged or rolled specimens
Steels / 189
only):
190 / Heat Treater’s
Guide
1045 : Microstructures.
(a) 2% nital, 500x. 25.4 mm (1 in.) bar stock. Normalized by austenitizing at 845 “C (1555 “F). Air cooled. Tempered at 480 “C (895 “F), 2 h. Fine lamellar pearlite (dark) and ferrite (white). (b) Picral, 500x. Sheet, 3.175 mm (l/8 in.) thick. Normalized by austenitizing at 1095 “C (2005 “F). Cooled in air. Structure is peariite (dark gray) and ferrite (light). (c) Picral, 500x. Same as (b), except bar specimen used. Grain size much larger. Pearlite (gray) with network of grain-boundary ferrite (white) and a few side plates of ferrite. (d) Picral, 330x. Forging air cooled from forging temperature of 1205 “C (2200 “F). The structure consists of envelopes of proeutectoid ferrite at prior austenite grain boundaries, with emerging spines of ferrite, in matrix of pearlite. (e) 4% picral, 500x. 50.8 mm (2 in.) bar stock, austenitized at 845 “C (1555 “F), 2 h. Oil quenched, 15 sec. Air cooled, 5 min. Quenched to room temperature. Ferrite at prior austenite grain boundaries. Acicular structure probably upper bainite. Pearlite matrix (dark). (f) 2% nital, 100x. Forging austenitized at 900 “C (1650 “F), 3 h. Air cooled. Tempered at 205 “C (400 “F) for 2 h. At top is layer of chromium plate. Below, layer of martensite, due to overheating during abrasive cutoff. Remainder, ferrite and pearlite. (g) Picral. 500x. Austenitized at 1205 “C (2200 “F), 10 min. Held at 340 “C (640 “F) for 10 min, for partial isothermal transfonation. Cooled in air to room temperature. Lower bainite (dark) in matrix of martensite (white). (h) 2% nital, 500x. 50.8 mm (2 in.) bar stock. Austenitized 2 h at 845 “C (1555 “F). Oil quenched, 15 sec. Air cooled, 3 min. Water quenched to room temperature. Specimen from 3.175 mm (l/8 in.) below surface. Dark stripes at prior austenite grain boundaries are probably upper bainite. Matrix is martensite. (j) 4% picral, 500x. 50.8 mm (2 in.) bar stock. Austenitized 2 l/2 h at 845 “C (1555 “F). Water quenched, 4 sec. Air cooled, 3 min. Water quenched to room temperature. Specimen from 3.175 mm (l/8 in.) below surface. Dark, acicular structure probably lower bainite. Light matrix of martensite. (k) 4% picral, 500x. Same as (j), except somewhat different structure. Gray aggregate probably upper bainite. Fine, acicular dispersion probably lower bainite. Martensite matrix
Nonresulfurized
Carbon
Steels / 191
1046 Chemical Composition. AISI and UNS: 0.43 to 0.50 C, 0.70 to 1.OOMn, 0.040 P max, 0.050 S max Similar Steels (U.S. and/or Foreign). A510, A576; SAE J403,5412,5414
UNS G10460; ASTM
Characteristics. Higher manganese version of 1045 provides for slightly higher hardenability. As-quenched hardnessof at least 55 HRC. Slightly higher when carbon is near high side of the allowable range. Used extensively for parts to be furnace heated or heatedby induction prior to quenching. Excellent forgeability. Fair machinability
Recommended l l
l
l l l
Forging.
Heatto 1245“C (2275 “F). Do not forge below 870 “C (1600 “F’)
Recommended Normalizing.
Heat Treating
Practice
Heat to 900 “C (1650 OF).Cool in air
Annealing. Heat to 845 “C (1555 “F). Furnacecool to 650 “C (1200 “F), at a rate not to exceed28 “C (50 OF)per h
l l
Processing
Sequence
Forge or machine (bars) Normalize (if forged. Not required for parts machined from hot rolled or cold drawn bars) Anneal (if necessary.Bar stock usually received in condition for best machining) Rough machine (forgings) Austenitize (parts from bars or forgings) Quench Temper Finish machine 1046: Quenchina Specimen. 22.225 mm (0.875 in.) diam by 76.2 mm (3 in.). Quenched from 815 “C (1506 “F)
Hardening. Austenitize at 845 “C (1555 “F). Flame hardening, induction hardening, and carbonitriding are suitable surface hardening processes.Quench in water or brine. Rounds under 6.35 mm (0.25 in.) diam may be oil quenched for full hardness Tempering After Hardening. Hardnessof at least 55 HRC if properly austenitized and quenched.Hardnesscan be adjustedby tempering Tempering After Normalizing. Normalize and temperas for 1040. For large sections, normalize by conventional practice. This results in a structure of line pearlite. A tempering treatmentup to about 540 “C (1000 OF)is then applied. Mechanical properties not equal to those achieved by quenching and tempering. Resulting strength is far higher than that of annealed structure. Normalizing and tempering often applied to heavy forgings
1046: Variations in Hardness After Tempering. Forged specimen heated to 830 “C (1525 “F). Quenched in caustic. Tempered 1 h to range of hardness, 285 to 321 HB. Forgings heated in continuous belt-type furnace and individually dump quenched in agitated caustic. Forgings, 44 to 53 kg (95 to 115 lb) each. Maximum section was 38.1 mm (1.50 in.)
1046: Hardness vs Tempering Temperature. Specimen, 57.15 to 63.5 mm (2.25 to 2.50 in.) thick. Quenched
192 / Heat Treater’s
Guide
1049 Chemical Composition. AISI 0.90 Mn. 0.040 P max. 0.050 S max
and UNS: 0.16 to 0.53 C. 0.60 to
Similar
Steels (U.S. and/or Foreign). UNS G 104YO; ASTM AS IO. AS76: SAE J-103.531 7.53 I-t: (Ger.) DIN I I301 : (Fr.) AFNOR XC 48 TS; (Jap.) JIS S SO C: (Swed.) SS1.t 1660
Hardening. Heat to 830 “C ( 1525 “Ft. Flame hardentng and carbonitridinp are suitable surface hardening processes. Quench in water or brine. Rounds less than 6.35 mm (0.75 in.) diam may be fully hardened by oil quenching. Normalize and temper as for IO-IO Tempering. downward
Characteristics. As-quenched hardness of at least 57 HRC. e\en with carbon on the lo\\ side of the allowable range. As-quenched hardness will usually approach 60 HRC. when the carbon is near the maximum. 0.53. Excellent forgeability. Fairly good machinability. \!‘eldability is poor Forging.
Heat to I230 “C (2250 “F). Do not forge belou 8-U “C t IS55 “F)
Recommended
Normalizing.
Heat Treating
Heat to 900 “C (I650
Practice
l
l l
“F). Cool in air
l l
Annealing.
Heat to 830 “C (I 525 “FL Furnace cool to 650 “C ( I ZOO “FL at a rate not to exceed 28 “C (SO “F) per h
1049: Hardness
vs Tempering
Temperature.
to 6.35 mm (0.125 to 0.25 in.) thick. Quenched.
Specimen, Tempered
3.175 1h
Processing
Sequence
Forgings l
Recommended
As-quenched hardness of 57 to 60 HRC can be adjusted by proper tempering temperature
l l
Forge Normalize Anneal Rough machine Austenitire Quench Temper Finish machine
1049:
Hardness
34.925
to 79.375
vs
Tempering
mm (1.375
Temperature. Specimen, to 3.125 in.) thick. Quenched
192 / Heat Treater’s
Guide
1050 Chemical
COIIIpOSitiOn.
MS1
and
UNS:
0.48
to 0.55 C. 0.60 to
0.90 Mn. 0.040 P max. 0.050 S max
AhlS Steels (U.S. and/or Foreign). GINS G~osoo; 5085; ASTM A5 IO. A5 19. AS76. A683: FED QQ-S-635 (C 1050). QQ-S700(C1050):~i~SPECMIL-S-1697~:SAEJ-103.5117.J-II-I:(Ger.)DIN I. I2 IO; (Jap.) JIS S 53 C. S 55 C Similar
Characteristics.
Carbon content as high as 0.55. Borderline between I medium carbon and a high-carbon grade. Used extensively for producing small to medium size forgings. Often selected for parts to be induction hardened. Fully quenched hardness of at least 58 to 60 HRC, especially when carbon is on the high side of the range. Excellent forgeabilib. Fair11 good machinability. Weldability is poor. Not available as an H grade
Forging.
Heat to I230 “C (2250°F).
Recommended Normalizing. Annealing.
Do not forge below 845 “C (IS55 “F)
Heat Treating
Practice
Tempering.
Recommended Forgings l
Forge Normalize
l
Anneal
l
Rough machine Austenitize Quench Temper Finish machine
l
l
t I200 OF).
hardening, induchardening are suitbrine. Rounds less by oil quenching.
As-quenched hardness of 58 to 60 HRC can be reduced by the proper tempering temperature
l
Heat to 900 “C (I650 “F). Cool in air
Heat to 830°C (I 525 “F). Furnace cool to 650°C at a rate not to exceed 18 “C (SO “F) per h
Hardening. Austenitize at 830 “C t, IS25 W. Flame tion hardening. carbonitridinp. austempering. and laser able surfrlce hardening processes. Quench in water or than 6.35 mm (0.15 in.) diam may be fully hardened Normalize and temper as for IWO
l l
Processing
Sequence
Nonresulfurized
1050:
As-Quenched
Hardness
(Oil)
round
in.
mm
Surface
Eardness, ERC ‘/r radius
Center
‘/2 I 2 4
12.7 25.-l SO.8 101.6
57 33 27 98 HRB
37 30 25 95 HRB
34 26 21 91 HRB
Source: Bethlehem
Steels / 193
1050: Isothermal Transformation
to 0.55 C, 0.80 to 0.90 Mn, 0.090 P max, 0.050 S max; grain Grade:.0.48 size 5 to 7 Si
Carbon
C, 0.91 Mn. Austenitized Martensite temperatures
Diagram. Composition: 0.50 at 910 “C (1670 “F). Grain size, 7 to 8. estimated
Steel
1050: Effect of Carbon and Manganese on End-Quench Hardenability. Modified 1050. 0: 0.51 C, 1.29 Mn, 0.06 residual Cr; 0: 0.52 C, 1.27 Mn, 0.06 residual Cr; LO.48 C, 1.07 Mn. 0.06 residual Cr; kO.51 C, 1.04 Mn, 0.08 residual Cr
1050: Flame Hardening
1050:
As-Quenched
Hardness
(Water)
Grade: 0.48 to 0.55 C, 0.60 to 0.90 Mn. 0.040 P max, 0.050 S max; grain size 5 to 7 Si
round
in.
mm
‘/:
II.7 25.1 SO.8 101.6
I 2 4 Source: Bethlehem
Steel
Surface 6-t 60 SO 33
Eardness. HRC ‘/z radius 59 35 32 27
Center 57 33 16 20
1050: Hardness vs Tempering Temperature and Chemical Composition
194 / Heat Treater’s
Guide
1050: End-Quench
1050: Hardness vs Tempering Temperature. Specimen, 3.175
Mn. Austenitized
Hardenability. Composition: 0.46 C, 0.99 at 845 “C (1555 “F). Grain size, 7
to 6.35 mm (0.125 to 0.25 in.) thick. Quenched.
1050: Furnace vs Induction
Tempered 1 h
Hardening. Brine quenched from
855 “C (1570 “F)
1050: Tempering. Effect of tempering temperature on room-temperature mechanical properties of 1050 steel. Properties summarized are for one heat of 1050 steel that was forged to 38 mm (1.50 in.) in diameter, then water quenched and tempered at various temperatures. Composition of heat: 0.52% C. 0.93% Mn
Nonresulfurized
1050: Induction Heating. Variations of room-temperature hardness with tempering temperature for furnace and induction heating
Carbon
Steels / 195
1050: Austempering. Variation in pitch length of 2 mm (0.080 in.) thick link plates after austempering and after oil quenching and tempering. All link plates were austenitized at 855 “C (1570 “F) for 11 min; austempered link plates were held in salt at 340 “C (650 “F) for approximately 1 h, a time dictated by convenience in processing but not required to attain complete transformation
1050: Microstructures. (a) Nital, 825X. Austenitized at 870 “C (1600 “F). l/2 h. Oil quenched. Slow quenching permitted formation of some grain-boundary ferrite and bainite (feathery areas). Matrix is martensite (white). (b) Austenitized at 870 “C (1600 “F); 1 h. Water quenched. (c) Nital, Tempered at 260 “C (500 “F), 1 h. Structure is fine-tempered martensite. No free ferrite visible, indicating quench was effective. 825x. Same as(b) except tempered at 370 “C (700 “F), 1 h. Tempered martensite. (d) Nital, 825x. Same as (b), except tempered at 480 “C (895 “F), 1 h. Tempered martensite. Ferrite and carbide barely resolved. (e) Nital, 825x. Same as (b), except tempered at 595 “C (1105 “F). Tempered martensite. Ferrite and carbide better resolved. (f) Nital. 913x. Same as (d). Replica electron micrograph. Typical of a thoroughly quenched structure
Nonresulfurized
Carbon
Steels / 195
1053 Chemical
Composition.
AISI and UNS: 0.18 to 0.55 C, 0.70 to
I .OO Mn. 0.040 P max. 0.050 S max
Similar
Steels (U.S. and/or
ASIO. AS76: SAE J-103. J-II?. J-II-I
Foreign).
UNS
Gios30;
ASTM
196 / Heat Treater’s Guide Characteristics. Similar IO 1050. except a higher manganese content which slightly increases hardenability. In some application. higher hardenability is useful. Ln induction hardening. higher hardenability ma) cause quench cracking. Excellent forgeability. Fairly good machinabilit>. Weldability is poor Forging.
Heat IO I230 “C t2250 “F). Do not forge below MS “C t IS55 “F)
Recommended Normalizing.
Heat Treating
Annealing.
Heat to 830 “C t IS25 ‘Ft. Furnace cool to 650 ‘C t 1200°F). at a rate not to exceed 28 “C (SO “F) per hour
Hardening. Heat to 830 “C t 1525 ‘FL Carbonitriding and induction hardening are suitable processes. Quench in Water or brine. Rounds less than 6.35 mm tO.3 in.) diam may be oil quenched for full hardness. Normalize and temper. as for 1040 Tempering.
As-quenched hardness of 58 to 60 HRC can be reduced bj proper tempermg temperature
Forgings l l
Forge Normalize
Processing
l l l l l
Anneal Rough machine Austenitize Quench Temper Finish machine
Practice
Heat 10 900 “C t I650 “FL Cool in air
Recommended
l
Sequence
1053: Hardness vs Tempering Temperature. Represents average based on a fully quenched
structure
196 / Heat Treater’s
Guide
1055 Chemical
Composition.
AISI and UN% 0.50 10 0.60 C. 0.60 to
0.90 hln. O.WO P max. 0.050 S max
Similar
l
Steels (U.S. and/or Foreign).
ASIO. AS76. A682 FEDQQ-S-7OO(ClOSS): DIN I.1209
LINS G 10550: ASTM SAE J403. J-112. J-l I-l: (Ger.)
Characteristics. Generally considered a high-carbon steel. When carbon approaches 0.60 a near saturated martensite is formed after austemtiring and severe quenching. As-quenched hardness of 60 to 6-I HRC is ohtained. depending on carbon content. A shallou hardening or low-hardenabilib steel. Good forgeability. Poor machinabilit). Not recommended for welding Forging.
Heat to I205 “C (2200 “F). Do not forge below 8 IS “C ( I SO0 ‘F)
Recommended Normalizing.
Heat Treating
Practice
Heat to YOO “C ( 1650 “FL Cool in au
Annealing.
Heat to 830°C ( IS25 “F). Furnace cool to 650 “C ( 1200°F). at a rate not to exceed 28 “C (SO “F) per h
Hardening. Heat to 830 ‘C (I 525 “F). Flame hardening and carbonitriding are suitable surface hardening processes. Quench in inter or brine. Rounds less than 6.35 mm (l/-l in.) diam may be oil quenched for full hardness. Nomlalize and temper as for I040 Tempering.
As-quenched hardness of 60 to 6-l HRC can be reduced b! proper tempering temperature
Recommended Forgings l l l l
Forge Normalize Anneal Rough machine
Processing
Austrnitize Quench @ Temper l Finish machine l
Sequence
1055: Isothermal Transformation C, 0.46 Mn. Austenitized Martensite temperatures
Diagram. Composition: 0.54 at 910 “C (1670 “F). Grain size, 7 to 8. estimated
Nonresulfurized
Carbon
Steels / 197
1055: End-Quench
1055: Hardness vs Tempering Temperature. Represents
Mn. Austenitized
average based on a fully quenched
Hardenability. Composition: 0.47 C, 0.57 at 845 “C (1555 “F). Grain size, 6 to 7
an
structure
1055: Microstructures. (a) Picral, 1000x. 6.35 mm (0.25 in.) diam rod, patented by austenitizing 2 l/3 min at 930 “C (1705 “F). Quenched 35 set in lead bath at 550 “C (1020 “F). Air cooled. Unresolved pearlite (dark). Ferrite (white), at prior austenite grain boundaries. (b) Picral, 1000x. 3.353 mm (0.132 in.) diam wire. Air patented by austenitizing 1 112 min at 1032 “C (1890 “F). Air cooled in strand form. Line lamellar peadite with discontinuous precipitation of ferrite at prior austenite grain boundaries
Nonresulfurized
Carbon
Steels / 197
i 059 Chemical COIIIpOSitiOn. AISI and UNS: 0.55 to 0.65 C. 0.50 to 0.80 Mn, 0.040 P max. 0.050 S max (standard steel grade for wire rod and wire only)
Recommended Hardening. hardening
Heat Treating
Flame hardening processes
Practice
and carbonitriding
are suitable
surface
Nonresulfurized
Carbon Steels / 197
1060 Chemical Composition. AI!31 and UNS: 0.90 Mn. 0.040 P max. 0.050 S max
0%
to 0.65 C. 0.60 IO
AMS Similar Steels (U.S. and/or Foreign). LINS G IOhoo; 7230; ASTM ASIO. AS76, A682 MLL SPEC MlL-S-16973: SAE J-103. J-113. J-II-I: (Ger.) DIN 1.0601: (Fr.) AFNOR CC 55: (Ital.) LINI C 60: (U.K.) B.S. 060 A 63
Characteristics.
Versatile high-carbon grade. Product forms include \ erious thicknesses of flat stock for fabricating parts to be spring tempered. Good forgeability. Not recommended for welding. As-quenched hardness of near65 HRC. This is near maximum Rockwell hardness. When properly quenched. consists of 3 carbon-rich martensite structure with essentially no free carbide
198 / Heat Treater’s Guide Forging.
Heat to I205 “C (2200 “FJ. Do not forge below 8 IS “C ( IS00 OF)
Recommended Heat Treating Practice Normalizing. Heat lo 885 “C (I625 “FJ. Cool in air Annealing. Heat to 830 “C (IS25 ‘VI. Furnace cool to 650
1060: Isothermal Transformation C, 0.87 Mn. Austenitized Mattensite temperatures
Diagram. Composition: 0.63 at 815 “C (1500 “F). Grain size, 5 to 6. estimated
“C ( I200 “F),
at a rate not fo exceed 28 “C (SO “F) per h
Hardening. austempering,
Heat to 8 IS “C (1500 “F). Flame hardening, carbonitriding, and martempering are suitable surface hardening processes.
Quench in water or brine. Rounds under 6.35 mm (0.25 in.) diam may be oil quenched for full hardness
Tempering.
As-quenched hardness from 62 to 65 HRC. This maximum hardness can be reduced by proper tempering temperature
Austempering.
Thin sections (typically springs) are austempered. Re-
sults in a bainitic structure and hardness of approximately 46 to 52 HRC. Austenitize at 8 IS “C ( IS00 “F). Quench in molten salt bath at 3 IS “C (600
“F). Hold at temperature for at least I h. Air cool. No tempering required
Recommended Forgings
Processing
Sequence
Forge
l l
Normalize
l
Anneal Rough machine
l
l
Austenitize Quench Temper
l
Finish machine
l l
1060:
1060: Hardness vs Tempering Time. Machine tool component forging, 114.3 mm (4.5 in.) long. Rectangular cross section, 15.875 by 22.225 mm (0.625 by 0.875 in.). Heated at 815 “C (1500 “F) in pusher conveyor furnace. Oil quenched. Tempered at 480 “C (895 “F) in muffle furnace. Both furnaces gas fired. No atmosphere control. Hardness measured on polished flash line. 20 heats
As-Quenched Hardness (Oil)
Grade: 0.55 to 0.65 C, 0.60 to 0.90 Mn, 0.040 P max, 0.050 S max: grain size 5 to 7 (90%); 1 to 3 (10%)
In.
Size round IlUll
Surface
Eardness, ERC ‘/r radius
Center
‘/2
12.7 25.1 SO.8 IOl.6
59 3-l 30.5 29
37 32 27.5 26
35 30 25 2-l
I 2 -I Source: Bethlehem
Steel
1060: End-Quench
1060: Hardness vs Tempering Temperature. 4.673 to 104.775
Mn. Austenitized
mm (0.19 to 4.125 in.) thick. Quenched
Hardenability. Composition: 0.63 C, 0.87 at 815 “C (1500 “F). Grain size, 5 to 6
Nonresulfurized
Carbon Steels / 199
Equipment Requirements for Austenitizing, Austempering, and Corrosion Protection of Parts Made of 1035 and 1060 Steels Equipment comprises a manually operated monorail heat-treating
line
Production requirements Pall Steel Section Ihickness. mm fin., Weight of part. kg (lb) Load weight (gross). kgflb) Number of pieces per h Preheating, “C (“Fk min Austenitizing, “C(“F); min Austempering, “C (OF); min
Equipment requirements Preheting furnace Amount ofchloride sah. kg (lb) Austenitizing furnace Amount ofchloridesalt. kg(lb) Ausrempering furnace Amount of nitrate-niuite salt, kg (lb) Heat input. kJ (Btu) per h Agitation Two washing and rinsing tanks Capacity. each tank Heat input. each tank, kJ (Btu, per h Tank for corrosion protection, m fin.)
Fabricated
disk
12.5 (0.492, I.1 (2.5)
Recuwgular tube 1060 I.4 fO.055, 0.2 (0.425)
163 (360) 332 705 ( 1300); 10 815-870 ( I SSO-1600); 10 425 (800); IO
35.7(78 75) 720 705 ( 1300): 5 83Ot 1525): IO 345 (650): 6
1035
Rectangular pkue 1060
0.8 (0.032) 0.01 (0.024 7.3 ( 16) 3!900 70.5( 1300); 5 83Ofl525);
IO
330 (630); 6
Immersed-electrode sah bruh. 0.45 hy 0.6 bj I .6 m ( I8 by 2-l hy 62 in.) 590(1300) Immersed-electrode salt bath. 0.45 by 0.6 hp I .6 m ( I8 by 3-l hy 61 in. 1 59Ofl300) Gas-fwd salt halh. 0.6 by I.2 hy I .8 m 121 hy 18 by 72 in. I
2270 (SOOO, 7-lO.000 (7OO.000) IXvo 150mmf6in.~impellers Gas-tired, hot water: each 0.5 by 0.9 hy I 1 m (20 b! 36 hy 18 in.) 57oLfl5ogal~ 316.000~300.COO, 0.5 by 0.9 hy I.2 m (20 by 36 by 18 in.)
1060: Miichrres. (a) Picral, 1000x. 6.35 mm (0.25 in.) diam rod. Cooled from hot rolling in single strand by high-velocity air blast. Mostly unresolved peartiie. Some diinctly lamellar pearliie. Few scattered white areas are ferrite, partly outlining ptioraustenite grains. (b) Picral, 1000x. 6.747 mm (0.266 in.) dim rod, patented by austenitizing at St.5 “C (1730 “F), 2.50 min. Quenched in lead bath at 530 “C (WI “F), 55 sec. Aircooled. Peariiie (dark areas) and ferrite (wbiie) at prior austenite grain boundaries. (c) Picral, 1000x. 7.137 mm (0.281 in.) diam win?. Air patented by austenitizing at 1055 “C (1930 OF),3 min. Air cooled in strand form. Partly resolved peadiie (dark). Ferrite (white) at prior austenltizing grain boundaries. (d) Piiral, lOOOx. 2.515 mm (0.099 in.) diam wire. Air patented by austenitizing at 1015 “C (1860 “F), 1 min. Air cooled in strand form. Fine pearfiie (dark), mostly unresolved. Some ferrite at prior austenite grain boundaries. (e) Picral, 100x. Decarburized. Heated to 1205 “C (2200 “F), 1 h before rolling to size. Thin layer of scale at surface(topofmicrograpb). Decarburizedwhiielayerneartop. Unresolvedpeartiie,fenfte. (9 Picral, 500x. Decatburfzed. Heatedto870to925”C(1600 to 1695 “F), 12 min. Air cooled. Scale at top of micrograph Partly decarburfzed layer, below scale. Pearfiie (dark). Some grain-boundary ferrite
200 / Heat Treater’s
Guide
1064 Chemical COIIIpOSitiOrl. AISl 0.80 hln. 0.040 P max. O.OSO S max
and LJNS: 0.60 to 0.70 C. 0.50 to
Recommended Hardening. Flame hardenmg processes
1064: Microstructure. 1064 cold-rolled steel strip, heated to 745 “C (1370 “F), furnace cooled to 650 “C (1200 “F), and air cooled to room temperature. Structure is fine spheroidal cementite in a matrix of ferrite. This structure is preferred for subsequent heat treatment. Picral. 500x
Heat Treating hardening
Practice
and carhonitiding
are suitable
surface
1064: Microstructure. 1064 cold-rolled steel strip, austenitized at 815 “C (1500 “F), quenched to 315 “C (600 “F) and held tocomplete isothermal transformation, air cooled, and tempered at 370 “C (700 “F). The structure is a mixture of bainite and tempered martensrte. Picral. 500x
200 / Heat Treater’s
Chemical
Guide
Composition.
AISI and UN% 0.60 to 0.70 C. 0.60 to
Recommended
Heat Treating
Practice
0.90 hln. 0.040 P max. 0.050 S niax
Hardening. ma-tempering
Flame hardening. carhonitriding. are suitahle processes
austempering,
and
1065: Microstructure. 1065 steel wire, 3.4 mm (0.14 in.) in diameter, patented by austenitizing 1.5 min at 930 “C (1705 “F), quenching 30 s in a lead bath at 545 “C (1015 “F), and air cooling. The structure is mostly unresolved pearlite with some grainboundary ferrite. Picral. 500x
Nonresulfurized
Carbon
Steels / 201
1069 Chemical
Composition.
AK1 and IJNS: 0.65 to 0.75 C. 0.40 to
Recommended
Heat Treating
Practice
0.70 Mn. 0.040 P max. 0.050 S max
Hardening. hardening
Flame hardening processes
and carbonitriding
are suitable
surface
Nonresulfurized
Carbon
Steels / 201
1070 Chemical
0.90Mn,
Composition.
AISI and UN% 0.65 to 0.75 C. 0.60 to
0.040 P max. 0.050 S max
Steels (U.S. and/or Foreign). UNS Gl0700; AMS 51 IS; ASTM A510. A576, A682; MLSPEC MIL-S-11713 (2):SAEJ303, J4 12. J4 14: (Ger.) DIN I. I23 I ; (I?.) AFNOR XC 68; (Swed.) SS~J 1770. 1778 Similar
Characteristics.
Low hardenability. Widely used in hardened and tempered (notably, spring tempered) condition. Good forgeability and shallow hardening. Used extensively for making hand tools. such as hammers and woodcutting saws. Fully hardened microstructure is carbon-rich martensite with some small undissolved carbides. Carbides not present in 1060. due to lower carbon content. Although same hardness as 1060 (65 HRC). existence of some free carbide gives 1070 greater resistance to abrasive wear. Not recommended for welding
Forging.
Heat to I I90 “C (2 I75 “F). Do not forge below 8 I5 “C ( I500 “F)
Recommended Normalizing.
Heat Treating
Practice
Heat to 885 “C ( I625 “F). Cool in air
Annealing.
Heat to 830 “C (I525 “F). Furnace cool to 650 “C (I 200 “F). at a rate not to exceed 28 “C (50 “F) per h
austempering, and martempering are suitable surface hardening processes. Quench in water or brine. Rounds under 6.35 mm (0.25 in.) diam may be oil quenched for full hardness
Tempering.
As-quenched hardness approximately can be reduced by proper tempering
Austempering.
Thin sections (typically, springs) are austempered. Results in a bainitic structure and hardness of approximately 46 to 52 HRC. Austenitize at 8 I5 “C (I 500 “F). Quench in molten salt bath at 3 IS “C (600 “F). Hold at temperature for at least I h. Air cool. No tempering required
Martempering. I75 “C(3-kS
hardening,
Heat to 815 “C (1500 “F). Flame hardening, induction carbonitriding. laser hardening. electron beam hardening,
1070: Isothermal Transformation Diagram. Composition: 0.75 C, 0.70 Mn, 0.017 P, 0.016 S, 0.33 Si, 0.20 Ni, 0.17 Cr. Austenitized at 600 “C (1470 “F). Grain size, 5 to 6. Time held in constant temperature bath from start of quench
Austenitize
at 8-U “C ( IS55 “F). Martemper
“F)
Recommended
Processing
Sequence
Forgings l l l l l l
Hardening.
65 HRC. Hardness
l l
Forge Normalize Anneal Rough machine Austenitize Quench Temper Finish machine
1070: Temperature
vs Depth of Case
in oil at
202 / Heat Treater’s
Guide
1070: Hardness vs Depth of Case
1070: Hardness vs Tempering Temperature. Represents average based on a fully quenched
an
structure
1070: Microstructures. (a) 2% nital, 100x. Hard drawn steel valve-spring wire, Longitudinal section. Tensile strength, 1689 MPa (245 ksi, obtained by 80% reduction. Deformed pearlite. Prior structure, fine lamellar pearlite. (b) 2% nital, 1000x. Valve-spring wire. Quenched and tempered. Austenitized at 870 “C (1600 “F). Oil quenched. Tempered at 455 “C (850 “F). Mainly tempered martensite. Some free ferrite (white)
202 / Heat Treater’s Guide
1075 Chemical Composition. AISI 0.70 Mn, 0.040 P max. 0.050 S max
and UNS:
0.70 to 0.80 C. 0.40 to
Recommended
Heat Treating
Hardening. Flame suitable processes
hardening,
Practice
carbonitriding.
and austempering
are
202 / Heat Treater’s
Guide
1078 Chemical Composition. AISI 0.60 Mn. 0.040 P max. 0.050 S max Similar
Steels (U.S. and/or
A510.A576;SAEJ4O3,Jdl2.Jll-k(Ger.)DIN 75: (Swed.) Ss1.1 1774
Characteristics.
and UNS:
Foreign).
0.72 to 0.85 C. 0.30 to UNS G10780; ASTM l.l218:(Fr.)AFNORXC
High carbon allov+s more free carbide particles in quenched microstructure. Because lower manganese decreases hardenabil-
ity. 1078 is often induction hardened. As-quenched hardness of 64 to 66 HRC. if properly austenitized and quenched. Forgeability is good. Never recommended for welding
Forging.
Heat to I I75 “C (2lSO”FL
Recommended Normalizing.
Do not forge below 815 “C (IS50 “F)
Heat Treating
Practice
Heat to 870 “C ( I600 OF). Cool in au
Nonresulfurized Annealing.
Heat to 8 IS “C ( I SO0 “F). Furnace cool to 650 “C ( I200 “F). at a rate not to exceed 28 “C (SO “F) per h
315 “C (600 “F). tempering required
Hardening. Heat to 815 “C ( 1500 “F). Carbonitriding, laser surface hardening, and induction hardening are suitable processes. Quench in water or brine. Rounds under 6.35 mm (0.25 in.) diam may be oil quenched for full hardness
Recommended
Tempering.
Asquenched hardness of approximately ness can be reduced by proper tempering temperature
65 HRC.
Hard-
at temperature
Processing
Steels / 203
for at least I h. Air cool.
No
Sequence
Forgings l l l l
Austempering. Because of low hardenability, thin sections only are austempered, as for 1060. Thin sections (typically springs) are austempered. Results in a bainitic structure and hardness of approximately 46 to 52 HRC. Austenitize at 815 “C (1500 “F). Quench in molten salt bath at
Hold
Carbon
l l l l
Forge Normalize Anneal Rough machine Austenitize Quench Temper Finish machine
1078: Isothermal Transformation Diagram. Composition: 0.75 C, 0.50 Mn, 0.007 P, 0.020 S, 0.27 Si. Horizontal lines: formation of martensite on cooling. Curved lines: formation of bainite on isothermal holding. Dotted lines: beginning of isothermal transfomation of holding below M,
1078: Hardness vs Tempering Temperature. Represents average based on a fully quenched structure
an
204 / Heat Treater’s
Guide
1078: Laser Surface Hardening. Laser surface transformation
hardening of SAE 1078 using optical integrator with 1.27 x 1.27 cm (0.5 x
0.5 in.) laser spot
1078: Microstructure. Picral, 550x. Hot rolled bar. Air cooled from rolling temperature. Predominantly pearlite. Large amount of partly resolved lamellar pearlite. Some grain-boundary ferrite
204 / Heat Treater’s
Guide
1080 Chemical COIIIpOSitiOn. AISI 0.90 hln. 0.040 P max. 0.050 S mux Similar
and UNS:
Steels (U.S. and/or Foreign).
5110: ASTM hIIL-S-16974;
0.75 to 0.88 C. 0.60 to
UNS Gl0800; ASIO. AS76. A68’: FED QQ-S-635 (CIOSO,: hlfL SAE 5403. J-II?. 141-J
AMS SPEC
Characteristics. Higher manganese content of 1080 can provide greater hardenabilit> than 1078. particulruly if manganese is near the high side of the range. 0.90. As-quenched hardness near 65 HRC. As carbon content increases. there is a gradual increase in amount of free carbide. This enhances abrasion resistance and decreases ductility. Forgeability is good. Weldabilitj is poor
Nonresulfurized
Forging.
Heat to I I75 OC (2 I50 OF’). Do not forge below 815 “C (I 500 “F)
Recommended Normalizing.
Heat Treating
Heat
to 870 “C (1600
Practice
“F).
Cool
Recommended
l
Annealing.
Heat to 815 “C (I 500 “F). Furnace cool to 650 “C (I 200 OF), at a rate not to exceed 28 “C (SO “F) per h
Hardening.
Heat to 8 I5 “C (I 500 “0. Induction hardening, carbonitriding, and austempering are suitable processes. Quench in water or brine. Rounds under 6.35 mm (0.25 in.) diam may be oil quenched for full hardness
l l l l l l l
As-quenched hardness of approximately ness can be reduced by proper tempering
65 HRC.
As-Quenched
Hardness
Sequence
Forge Normalize Anneal Rough machine Austenitize Quench Temper Finish machine
Hard-
Austempering. Because of low hardenability, thin sections are austempered, as for 1060. Thin sections (typically springs) are austempered. Results in a bainitic structure and hardness of approximately 46 to 52 HRC. Austenitize at 815 “C (IS00 “F). Quench in molten salt bath at 315 “C (600 “F). Hold at temperature for at least I h. Air cool. No tempering required
1080:
Steels / 205
Forgings
in air
Tempering.
Processing
Carbon
1080: Isothermal Transformation Diagram. Composition: 0.79 C, 0.76 Mn. Austenitized at 900 “C (1650 “F). Grain size, 6. Martensite temperatures estimated
(Oil)
Grade: 0.75 to 0.88 C, 0.60 to 0.90 Mn, 0.040 P max, 0.050 S max; grain size 80%, 5 to 7; 20%, 1 to 4 Size round in.
mm
‘/z I 2 .I
12.7 25.1 50.8 101.6
Source: Bethlehem
Surface 60 -I5 43 39
Eardness, ERC t/z radius 43 42 40 37
Center -IO 39 37 32
1080: Hardness vs Tempering Temperature. Specimen, 3.175 to 6.36 mm (0.125 to 0.25 in.) thick. Quenched.
Tempered 1 h
Steel
1080: End-Quench Hardenability. 12.7 mm (0.5 in.) diam bar. Composition: 0.79 C, 0.76 Mn. Austenitized at 900 “C (1650 “F). Grain size, 6
1080: P&s
Equipment austenitized
Production
for Austempering
requirements
Weight ofeach piece. kg (lb) Production per hour Equipment
Requirements
at 925 “C (1695 “F)
I. I to I .8 (2.-l to 3.9) I SO0 pieces
requirements
Austempering furnace Size of furnace. m3 (ft 3) Nitrae-write salt. kg (Ih, Tempenturr. “C (“FI Agitauon Cooling
Submerged fuel-fired salt pot 6.6(233) I I 340 (29 000) 34%360(65@675) Pump. directed at delivery chute Forced ar through humer tube
206 / Heat Treater’s
Guide
1060: TIT Diagram. Time-temperature austempering.
transformation diagram for 1080 steel, showing difference When applied to wire, the modification shown is known as patenting
1080: Induction Heating. Effect of heating rate on AC, and AC, temperatures
for annealed
1080 steel
between
conventional
and modified
Nonresulfurized
Carbon
Steels / 207
1080: Microstructures. (a) Picral. 2000x. Hot rolled bar, austenitized at 1050 “C (1920 “F), l/2 h. Furnace cooled to room temperature at 28 “C (50 “F) per h. Mostly pearlite. Some spheroidal cementite particles. (b) Thin-foil specimen, 2000x. Same as (a), except cooling rate increased to 56 “C (100 “F) per h. Thin-foil transmission electron micrograph. Fine lamellar pearlite. (c) As polished. Not etched. 250x. Inclusions in flat spring. 0.20 mm (0.008 in.) thick. Longitudinal section. Thickness shown as height in micrograph. Black spots are iron aluminide. Thin gray stringers near center are sulfide
Nonresulfurized
Carbon Steels / 207
1084 Chemical Composition.
AISI and UNS: 0.80
to
0.93 C, 0.60 to
0.90 Mn. 0.040 P max. 0.050 S max LINS ~10810; ASTM (C108-1); SAE 5303. J412. J-II-I: (Ger.) DIN
Heat to II75 “C (2lSO”Fl
Forge Normalize l Anneal l Rough machine l Austenitize 9 Quench l Temper l Finish machine l
Do not forgebelow
815 “C (l5OO’F)
1084: Hardness
Recommended Normalizing.
Heat Treating
Practice
average
Heat to 870 “C (1600 “F). Cool in air
Annealing. Heat to 8 I5 “C ( I500 “F). Furnace cool to 650 “C ( I 200 “F). at a rate not to exceed 28 “C (SO “F) per h Hardening. Heat to 8 IS “C ( I500 “F). Carbonitriding and austemperinp are suitable surface hardening processes. Quench in water or brine. Rounds under 6.35 mm (0.25 in.) diam may be oil quenched for full hardness Tempering.
Asquenched hardness of approximately ness can be reduced by proper tempering
Austempering.
Sequence
l
Characteristics. Composition nearly identical to that of 1080. Asquenched hardness near 65 HRC. As carbon content increases. there is a padual increase in amount of free carbides. This enhances abrasion resistance and decreases ductility. Forgeability is good. Weldabilitj is very poor Forging.
Processing
Forgings
Similar Steels (U.S. and/or Foreign). A510, A576; FED QQ-S-700 I .0647
Recommended
65 HRC.
Hard-
Very thin sections, because of relatively low hardenability can be austempered. using the technique for 1060. Thin sections (typically springs) are austempered. Results in a bainitic structure and hardness of approximately 46 to 52 HRC. Austenitize at 8 I5 “C ( IS00 “F). Quench in molten salt bath at 3 I5 “C (600 “F). Hold at temperature for at least I h. Air cool. No tempenng required
based
vs Tempering on a fully quenched
Temperature. structure
Represents
an
208 / Heat Treater’s
Guide
1085 Chemical
Composition. AISI and CJNS: 0.80 to 0.93 C. 0.70 to I .OOMn. O.@IOP max. 0.050 S max
Recommended Hardening.
Heat Treating
CarbonitridinS is a suitable surface hardening process
1085: Effects of Quenching on Hardness and Dimensions. Hardness values and changes in dimensions test specimen after quenching in water, fast oil, and conventional oil
Quenching medium
Maximum
Water . . . . . . . . . . . . . . . . . . . . . . . . . . 67.0 Fast oil . . . . . . . . . . . . . . . . . . . . . . . . 66.0 Conventional oil . . . . . . . . . . . . . . . . 65.5 Gap A mm Water . . . . . . . . . . . 0.3404 Fast oil . . . . . . . . . 0.0533 Conventional oil . 0.0559
in. 0.0134 0.0021 0.0022
Hardness, H RC Minimum
Variation
63.0 63.0 43.0 Dimensional Diameter 6
mm 0.2591 0.0813 0.0965
Practice
in. 0.0102 0.0032 0.0038
4.0 3.0 22.5 change Diameter mm 0.2946 0.0610 0.0965
C in. 0.0116 0.0024 0.0038
of a 1085 plain carbon steel
208 / Heat Treater’s Guide
1086 Chemical Composition.
Recommended
0.50 hln. 0.040 P nk. wire only)
Hardening.
AISI and CJNS: 0.80 to 0.93 C. 0.30 to 0.050 S max: (standard steel grade for uue rod and
Heat Treating
Carbonitriding
Practice
and austempering
are suitable processes
208 / Heat Treater’s
Guide
1090 Chemical
Composition.
AISI and LINS: 0.85 IO 0.98 C. 0.60
IO
0.90 h*ln. 0.040 P max. 0.050 S max
Similar Sll2:ASTM
Steels (U.S. and/or Foreign). A510. A576: SAEJ403.J-Il2.
LINS J-tl4:Ger.j
MIS GlO200; DIN I.1273
Characteristics. CommonJy referred to as a commercial grade of carbon tool steel. Essentially same composition as WI tool steel, hut not
made hy tool steel practice and not expected IO meet quality level of W 1 tool steel. Easily forged. Blanking (coldj from strip or thin plate is common method of fabrication. Available in a variety of product forms. As hard as 66 HRC, fully quenched. Microstructure of carbon-rich martensite and considerable amount of free carbide. assuming normal austenitizing temperature used
Forging.
Heat to I I50 ‘C (3 IO0 “Fj. Do not forge below 815 “C ( 1500 “Fj
Nonresulfurized
Recommended Normalizing.
Heat Treating
Recommended
Practice
Heat to 855 “C (1570 OF). Cool in air
Processing
Carbon
Steels / 209
Sequence
Forgings
Annealing.
As is generally true for all high carbon steels, bar stock supplied by mills in spheroid&d condition. Annerded with structure of fine spheroidal carbides in ferrite matrix. When parts are machined from bars in this condition, no normalizing or annealing required. Forgings should always be normalized. Anneal by heating to 800 “C (1475 “F). Furnace cool to 650 “C (1200 “F). at a rate not to exceed 28 “C (50 “F) per h. From 800 “C (I475 “F’) to ambient temperature, cooling rate is not critical. This relatively simple annealing process will provide predominantly spheroidized structure, desired for subsequent heat treating or machining
Hardening. Heat to 800 “C (1375 “F). Carbonitriding and austempering are suitable processes. Quench in water or brine. Rounds under 6.35 rnrn (0.25 in.) diam may be oil quenched for full hardness Tempering.
Asquenched hardness of as high as 66 HRC. Hardness can be reduced by proper tempering
Austempering.
Responds well to austempering (bainitic hardening). Austenitize at 800 “C ( 1475 “F). Quench in agitated molten salt bath at 3 I5 “C (600 “F). Hold for 2 h. Cool in air
l l l l l l l l
Forge Normalize Anneal Rough machine Semitinish machine Austenitize Quench Temper
1090: Hardness vs Section Thickness. Specimen, 20.828 mm (0.820 in.) diam. Austenitized at 885 “C (1625 “F). Quenched in salt at 370 “C (700 “F), 7 min. Rockwell hardness C, converted from microhardness readings taken with 100 g (4 oz) load. Low values of surface hardness result from decatburization
I
1090: llT Curves. Transformation characteristics of a hypereutectoid steel after mattempering. Austenitized at 885 “C (1825 “F). Grain size, 4 to 5
1090: Properties Sway Bars
Tensile suer@, hlPa (ksi) Yield strength. hPa (ksi) Elongation. 4. Reduction ofarea % Hardness. HB Fatigueqcles(d) (a) Alerage in diameter 95.220
of Austempered
and Oil-Quenched
Austempered at 400 “C (750 W(b)
Quenched sod tempered(c)
l-115 (205) 1020(148) II.5 30 115 105.OOChel
1380 (200) 895 (130) 6.0 10.2 388 58.6W f,
values (b) Six I~SIS. tc)lko tests cd) Fatigue specimens2 I mrn(O.812 in.) (et Seven tests: range, 69 050 to I37 000. (fj Eight tests; range, 13,120 to
1090: Hardness vs Section Thickness. Specimen,
1090: Hardness vs Tempering Temperature. average based on a fully quenched structure
Represents
an
17.272 mm (0.680 in.) diam. Austenitized at 885 “C (1625 “F). Quenched in salt at 370 “C (700 “F), 7 min. Hardness, HRC, converted from microhardness readings taken with 100 g (4 oz) load. Low values of surface hardness result from decarburization
210 / Heat Treater’s
Guide
1090: Microstructures. (a) Picral, 2000x. Hot rolled bar, 25.4 mm (1 in.). As cooled from finish-rolling temperature of 870 to 900 “C (1800 to 1850 “F). Replica electron micrograph. Entirely lamellar pearlite. (b) Picral, 1000x. 8.712 mm (0.343 in.) diam rod. Patented by austenitizing at 955 “C (1750 “F), 4 l/2 min. Quenched in lead bath at 505 “C (940 “F), 70 sec. Air cooled. Mostly unresolved pearlite with bainite. (c) Picral, 8000x. Strip, cold reduced 80% after hot rolling. Rolling direction vertical in this replica electron micrograph. Deformed lamellar pearlite. (d) 2% nital, 100x. Modified steel music wire. 0.38 Mn. Cold drawn to 1813 MPa ( 283 ksi) tensile strength by 75% reduction. Deformed pearlite. Prior structure, fine pearlite. (e) 2% nital, 500x. Same as (d), but higher magnification. Drawing direction is horizontal. Prior structure produced by lead patenting
210 / Heat Treater’s Guide
1095 Chemical COmpOSitiOn. AK1 0.50 Mn. 0.010 P max. 0.050 S max
and UNS:
0.90 to 1.03 C. 0.30
to
AMS Gl0200; UNS 5121. 5122. 5132. 7304; ASTM A510. A576. A682; FED QQ-S-700 (ClO95); MfL SPEC MB-S-16788 (CSlO95): SAE J303, JJIZ. J4l-k (Ger.) DIN I. 1274; (Jap.) JIS SUP 3: ISwed.) SS1.t 1870; (U.K.) B.S. 060 A96.EN44B
Characteristics. Easily forged. Blanking (cold) from strip or thin plate also a common method of fabrication. Available in a variety of product forms. As hard as 66 HRC, fully quenched. Microstructure of carbon-rich martensite and considerable amount of Free carbide. assuming normal austenitizing temperature is used. Carbon range slightly higher and manganese content lower than for 1090. This results in the possibility of more undissolved carbide in the microstructure and slightly lower hardenability Heat to I I50 “C (2 100 “F). Do not forge below 8 I5 “C ( 1500 ‘F)
Recommended Normalizing.
Heat Treating
practice.
parts are normalized
at 900 “C ( 1650 “F)
Annealing.
Similar Steels (U.S. and/or Foreign).
Forging.
In aerospace
Practice
Heat to 855 “C (1570 “F). Cool in au
As is generally true for all high-carbon steels, bar stock supplied by mills in spheroidized condition. Annealed with structure of fine spheroidal carbides in ferrite matrix. When parts are machined from bars in this condition. no normalizing or annealing required. Forgings should always be normalized. Anneal by heating to 800 “C (1475 OF). Soak thoroughly. Furnace cool to 650 “C ( I200 “F), at a rate not to exceed 28 “C (50 “F) per h. From 650 “C ( I200 “F) to ambient temperature, cooling rate is not critical. This relatively simple annealing process will provide predominantly spheroidized structure, desired for subsequent heat treating or machining. ln aerospace practice. parts are annealed allowed to cool to below 510 “C (I000 “F)
at 815 “C (1500 “F) and
Hardening. Heat to 800 “C (l-l75 “FL Carbonitriding and austempering are suitable processes. Quench in water. brine. or aqueous polymers. Oil quench rounds under A.7 mm (0. I9 in.) for full hardening. Responds well to austempering (same procedure as for 1090). In aerospace practice, parts are austenitized at 800 “C (1475 “F). and quenched in oil or polymers
Nonresulfurized Tempering.
As-quenched hardness as high as 66 HRC. Hardness can be reduced by proper tempering. When quenching with oils or polymers, parts may be tempered at a number of different temperatures to get specitic ranges of tensile strengths as follows: 675 “C (I 245 OF) for 620 to 860 MPa ( 90 to 125 ksi); 620 “C (I I50 “F) for 860 to 1035 MPa ( I25 to I50 ksi); 540 “C ( 1000 “F) for 1035 to I I70 MPa ( I50 to I70 ksi): 480 “C (895 “F) for 1170 to I240 MPa ( I70 to I85 ksi); 425 “C (795 “F) for 1240 to I380 MPa (185 to 200 ksi); 370 “C (700 “F) for I380 to I520 hiPa ( 200 IO 220 ksi)
Recommended
Responds well to austempering (bainitic hardening). Austenitize at 800 “C (1475 “F). Quench in agitated molten salt bath at 3 I5 “C (600 “F). Hold for 2 h. Cool in air
Steels / 211
Sequence
Forgings l l l l l l
Austempering.
Processing
Carbon
l l
Forge Normalize Anneal Rough machine Senlitinish machine Austenitize Quench Temper
1095: Effect of Prior Microstructure on Hardness After Tempering. Steel tempered at 565 “C (1050 “F) 1095: isothermal Transformation C, 0.29 Mn. Austenitized
Diagram. Composition: 0.89 at 885 “C (1625 “F). Grain size, 4 to 5
1095: End-Quench 1095: Isothermal Transformation
Diagram. Modified.
sition: 1.13 C, 0.30 Mn. Austenitized size, 7 to 8. Martensite temperatures
at 910 “C (1670 estimated
Compo“F). Grain
Mn. Austenitized
Hardenability. Composition: 0.89 at 885 “C (1625 “F). Grain size, 5
C, 0.34
212 / Heat Treater’s
1095:
As-Quenched
Guide
Hardness
(Water)
0.90 to 1.03 C, 0.30 to 0.40 Mn. 0.040 P max, 0.050 S max; grain Grade:,srze 50%, 5 to 7; 500/b, 1 to 4 Size round in.
mm
I .’ ,
12.7 3.1 SO.8
I2
-I
gas quenching
(forced air), and nor-
Center
55 Ib
48 4-l
63
43
-IO
63
38
30
b5 6-l
I0l.b
Source: Rcpuldic
Hardness, HRC % radius
Surface
1095: As-Quenched Hardness. Forged steel disks, 101.6 mm (4 in.) thick, after oil quenching, malizing (cooling in still air)
Steel
1095: Hardness vs Tempering Temperature. average based on a fully quenched
Represents
an
structure
1095: Cooling Curves. Center cooling curves showing the effect of scale on the cooling curves of 1095 steels quenched without agitation In fast oil at 51 “C (125 “F). Specimens were 13 mm (0.50 in.) diam by 64 mm (2.50 in.) long
1095: End-Quench Hardenability. C, 0.28 Mn. Austenitized
Modified. Composition: 1.17 at 925 “C (1695 “F). Grain size, 7 to 8
1095: Quenching. Differences in Brinell hardness of forged 1095 steel disks, 100 mm (4 in.) thick, after oil quenching, gas quenching (forced air), and cooling in still air (normalizing)
1095: Mechanical Properties Treated by Two Methods Specimen number I 2 3 4
Beat treatment Water quench and temper Waterquench and temper hlartrmpcr and temper Matemper and temper
(13) In 25 nun or I in.
of 1095 Steel Heat
Hardness, ARC 53.0 52.5 53.0 sz.l3
Impact energ J 16 I9 38 33
ft
Ibf I2 I-l 28 2-l
ElongaIion( %, 0 0 0 0
Nonresulfurized
1095: Microstructures.
Carbon Steels / 213
(a) Picral, 1000x. Bar, normalized by austenitizing at 870 “C (1800 “F). Cooled in air. Partly unresolved pearlite (black); partly lamellar peariite. (b) Nital, 1000x. Hot rolled bar, 31.75 mm (1.25 in.) diam. Spheroidized by holding at 875 “C (1245 “F), 15 h. Air cooled. Spheroidal cementite particles in ferrite matrix. (c) 2% nital, 500x. Wire, austenitized at 940 “C (1725 “F). Oil quenched. Mixture of fine pearlite and lower bainite (dark areas). Untempered martensite (light areas). Structure resulted from slack quenching. (d) Picral, 1000x. Austenitized at 870 “C (1800 “F); austenitized at 815 “C (1500 “F). Water quenched. Fine, untempered martensite. caused by more severe quench. Some spheroidal cementite. (e) Picral, 1000x. Same as (d), except tempered at 150 “C (300 “F) after quench. Tempered martensite. darker than (d). Some spheroidal cementite particles. (f) 2% nital, 550x. Wire. Austenitized at 885 “C (1625 “F), l/2 h. Quenched to 625 “C (330 “F). Held 5 min. Oil quenched. Lower bainite (dark). Untempered martensite (light). (g) 2% nital, 550x. Same as (f), except held for 20 min in 329 “C (625 “F) quench. Air cooled. Lower bainite (dark). Untempered marlensite (light). (h) 2% nital, 550x. Same as (f), except held 1 h in 445 “C (850 “F). Air cooled (austempered). Mainly upper bainite. (j) Nital, 500 x. Die steel induction hardened to 2.54 mm (0.10 in.). Shown are transition-zone constituents from some fine martensite (top) to prior structure of spheroidal cementite in ferrite matrix (bottom). (k) Nital, 500x. Same as (j), except area shown is nearer surface of steel. Fine martensite (gray) and fine unresolved pearlite (black). Small white particles are spheroids of cementite from prior structure. (n) Nital, 1000x. Same as (m), except higher magnification
214 / Heat Treater’s Guide
1095: Tempering. Effect of prior microstructure on room-temperature hardness after tempering. (a) 1095 steel tempered at 565 “C (1050 “F) for various periods of time. (b) Room-temperature hardness before and after tempering, as well as amount of martensite present before tempering in 4320 steel end-quenched hardenability specimens tempered 2h
Resulfurized (1100
Carbon
Steels
Series)
1108 Chemical
0.80Mn,
Composition.
AISI and UNS: 0.08 to 0.13 C, 0.50 to
Recommended
Heat Treating
Practice
0.040 P max. 0.08 to 0. I3 S
Hardening. hardening
Flame hardening processes
and carbonitriding
are suitable
surface
1110 Chemical Composition. AISI and UNS: 0.60Mn. 0.040 P max. 0.08 to 0.13 S Similar Steels (U.S. and/or Foreign).
0.08 to 0.13 C. 0.30 to
UNS Gi I 100; ASTM A 107; FED QQ-S-637 (C I I 10): SAE J-%03,J-l I?; (Ger.) DfN I .0702; (Jap.) JIS SUM II, SUM I2
Characteristics.
Available principally in bar form. Costs more than low-carbon steels of the 1000 series. because it has been resulfurized to improve machinability. Sulfur addition impairs some mechanical properties. mainly impact and ductility in the transverse direction. Also. adversely affects forgeability, cold formability, and weldability. Use of this steel
should be confined principally fabricating operation
Recommended Hardening. Large
to applications
Heat Treating
where machining
is the main
Practice
portion of parts are used as machined. Can be surface hardened by carbonitriding. salt bath nitriding, or flame hardening
Normalizing and Annealing. or hot roiled and cold drawn normalized or annealed
Generally furnished in the hot rolled condition for best machinability. Rarely
1113: Case Hardening Gradients. Case-hardness gradients scatter from normal variations in noncyanide liquid carburizing
1113 Chemical Composition.
AISI and UNS: 0. I3
C max.0.70 to l.OOMn.0.07
to0.12 P.O.14 too.33
S
Recommended Heat Treating Practice Hardening. Liquid carburizing is a suitable surface hardening process
of 1113 steel showing
216 / Heat Treater’s Guide
1117 Chemical Composition.
AISI and UNS: I.30 hln. 0.040 P max. 0.08 to 0. I3 S
Similar Steels (U.S. and/or Foreign). A107. Al08; FED QQ-S-637 (Clll7r; J-103.J-III. J-II-t
hlfL
0. I-4 to 0.20 C. 1.00 to
GINS
Gl I 170:
SPEC ML-S-IMII;
ASThl
SAE
Characteristics. Morecostly than the 1020 or IO2 I grades. because tt has heen resulfurized for improved machinability. This impairs certain mechanical properties. forgeability. and cold formability. Manganese content is substantially higher than that of 1020 and I02 I. Hardenahility is not significantly higher. because a portion of the manganese combines viith the
higher sulfur to form manganese sulfide stringers. These promote chip breakage and excellent machinability. Available only in bar stock for machining directly into parts. most often tn automatic machines
Recommended Case Hardening.
Heat Treating
Practice
Almost always used as machined or case hardened. (See process for 1020). Flame hardening. carbonitriding, liquid carbutizmg, gas carhuriring. austempering. and mat-tempering are suitable processes
Normalizing and Annealing. normalizing
teGtperature
Rarely required by fabricator. is 900 Y-( I hS0 “F) -
1117: Gas Carburizing. Effect of normal variations burizing on hardness gradients. 10 tests
Qpical _.
in gas car-
1117: Gas Carbonitriding. Carbonitrided at 815 “C (1500 “F), 1 l/2 h. Oil quenched. Required minimum hardness of 630 Knoop (500 g load) at 0.001 in. below surface was met by reducing percentage and flow rate of ammonia or by adding a diffusion period after carbonitriding, as indicated. Atmosphere consisted of: endothermic carrier gas, dew point of -1 “C (+30 “F), at 4.245 m3 (150 ft3) per h; natural gas at 0.170 m3 (6 W) per h; and ammonia in amounts indicated.0 : 3% NH, at 5 fWh. 0: 11% NH, at 20 ff/h and diffused last 15 min. A: 11% NH, at 20 ff/h
Resulfurized
1117: Liquid Carburizing. Comparative case depth and case hardness. Specimen, 15.875 mm (0.625 in.) diam. Carburized at 900 “C (1650 “F), 2 h. Brine quenched. 22 tests
1117:
As-Quenched
Hardness
52 I 2 -I
12.7 25.4 SO.8 101.6
Source: Bethlehem
Surface,
(Water)
‘/z radius
ERC
HRB
12 37 33 32
96 90 83
Center
HRC
HRB
3S.J
::
HRC ‘9.5
93 86 81
Steel
1117: Hardness vsTempering
Steels / 217
1117: Gas Carburizing. Effect of time and temperature on case depth. (a) Bars, 177.8 mm (7 in.) long. Carburized at 900°C (1650 “F). Water quenched. (b) Bars, 177.8 mm (7 in.) long. Carburized at 925 “C (1695 “F). Water quenched. (c) 12.7 mm (0.5 in.) round bars. Carburized at 900 “C (1650 “F). Quenched in 10% brine
Effect of mass on as-quenched hardness of steel bars, quenched in water; contents: 0.19 C, 1 .lO Mn, 0.015 P, 0.084 S. 0.11 Si; grain size: 2 to 4 Size round tn. mm
Carbon
Temperature. Represents an av-
erage based on a fully quenched structure
L
218 / Heat Treater’s Guide
1117: Selective Carburizing. Typical part selectively in the bath. Area to be carburized is shaded
1117: Microstructures.
carburfzed by partial immersion. Only the portion that is to be carbutized
is immersed
(a) Picral. 200x. Steel bar normalized by austenitizing at 900 “C (1650 “F), 2 h. Cooled in still air. Blocky ferrite (light). Traces of Widmanstatten ferrite. Fine pearlite (dark). Round particles of manganese sulfide. (b) 3% nital, 200x. Carbonitrided 4 h at 845 “C (1555 “F) in 3% ammonia, 6% propane, and remainder, endothermic gas. Oil quenched. Tempered 1 l/2 h at 150 “C (300 “F). Retained austenite (white) and globules of manganese sulfide (dark) in matrix of tempered martensite. (c) Nital, 200x. Carbonitrided and oil quenched. Surface layer of decarburized ferrite, superimposed on a normal case structure of martensite (left side of micrograph). Core material (right) shows patches of ferrite (white)
Resulfurized
Carbon Steels / 219
1117: Case Hardness Gradients. Case hardness gradients for two carbon steels and four low alloy steels, showing effects of carburizing temperature and time. Specimens measuring 19 by 51 mm (0.75 by 2 in.) diam were carburized, air cooled, reheated in neutral salt at 845 “C (1555 “F), and quenched in nitrate/nitrite salt at 180 “C (355 “F)
Resulfurized
Carbon Steels / 219
1118 Chemical COmpOSitiOn.
AK1 and UNS: 0.14 I .60 Mn, 0.040 P max. 0.08 to 0.13 S
Similar Steels (U.S. and/or Foreign). Al07,
Al08;
FED QQ-S-637
Characteristics.
to
0.20
C.
UNS G1 I 180; (Cl 118); SAE 5403, J412. J414
1.30
to
ASTM
More costly than the I020 or IO2 I grades, because it has been resulfurized for improved machinability. This impairs certain mechanical properties, forgeability, and cold formability, While a portion of the manganese (relatively high) combines with sulfirr, there is still a
sufftcient amount left over to result in higher hardenability 1020or 1021
Recommended
Heat Treating
compared
with
Practice
Case Hardening. Almost always used as machined or case hardened, as described for 1020. Greater hardenability. compared with 1020, allows the section thickness of carburized I I I8 to be extended at least to 12.7 mm (0.5 in.). Fully hardened by oil quenching. Flame hardening. carbonitriding, liquid carburizing. and martempering are suitable processes
220 / Heat Treater’s
Guide
1118: Liquid Carburizing.
Carburized
at 955 “C (1750 “F).
Slowly cooled
1118: Hardness vs Tempering Temperature. Represents an average based on a fully quenched
1118:
As-Quenched
Hardness
(Water) of steel bars, quenched in 0.08 S, 0.09 SI; grain size:
Size round in. mm ‘!I, I‘ 2 1 Source
Surface, ERC
IZ 7 25.-l SO.8 101.6 Brrhlcheni
Srrrl
43 36 34 32
‘,$ radius HRC 36 ___ _..
Center HRB
ERC
ClRB
33 9s, 91 8-i
96.5 87.0 82.0
structure
220 / Heat Treater’s
Guide
1137 Chemical
Composition. AISI and UNS: I .6S Mn. 0.040 P mari. 0.08 to 0. I3 S
Similar C: ASTM J-111
Steels (U.S. and/or Foreign). Al07,
AlO9. A3ll;
FEDQQ-S-637
0.31 to 0.39 C. 1.35 IO LINS G10200: AhlS 502-t (Cll37): SAE J-tO3. Jll2.
In aerospace practice. parts are normalized allowed to cool below S-10 ‘C t 1000 “F)
at 785 “C (1350 “F) and
Hardening.
Characteristics.
Essentially a high-manganese version of 1037. which has been resulfurized for improved machinabilib. Higher manganese content provides higher hardenability. although not as much as indicated by the manganese content t I .3S to I .65). Some of this manganese combines with increased sulfur to foml manganese sulfide stringers. Available only as hot rolled or hot rolled and cold drawn bars. for producing parts by machining processes. Too high m carbon for good weldability. Sulfur content can cause hot shortness. Should not be used L+hen welding is imolved
Recommended
Annealing. Heat IO 885 “C t 1625 OF). Furnace cool to 650 “C (1300 “F) at a rate not to exceed 38 ‘C (SO “F) per h to 650 “C ( 1200 “F).
Heat Treating
Practice
Normalizing. Not usually required If necessary, heat to 900 “C (I650 “FL Cool in air. In aerospace practice, parts are normalized at 900 “C (I650 “F)
Heat to 845 “C t I SSS “F). Flame hardening and carbonitridinp are suitable surface hardening processes. Quench in water. brine. or aqueous polymers. In aerospace practice. parts are austenitized at 845 “C (IS55 “F) and quenched in oil. \+ater. or polymer. For full hardness, oil quench sections not esceeding 9.535 mm (0.375 in.) thick
Tempering.
As-quenched hardness of approximately 45 HRC. Hardness can be reduced bq tempering In quenching with oils or polymers. parts ma> be tempered at several different temperatures to get specitic ranges of tensile strengths: 380 “C (895 “F) for 620 to 860 MPa (90 to 12.5 ksi); 329 “C (625 “F) for 860 to 1035 MPa (I 25 to I50 ksi). In quenching with water. more options are available. as follows: S-IO ‘C (I000 “F) for 620 to 860 hlPa t90 to I25 ksi); 480°C (895 “F) for 860 to 1035 MPa ( I25 to IS0 ksi): 125 ‘C (795 “FJ for 1035 to II70 hlPa t IS0 to 170 ksi): 370 “C (700 “F)
Resulfurized
for ll75to 1240MPa(l60to MPa(l80to2OOksi)
Strengthening
180ksij;3lS”C(6OO”F)for
12-lOto 1380
Recommended l
by Cold Drawing
and Stress Relieving.
l l
1137
1137
As-Quenched
Hardness
(Water)
Effect of mass on as-quenched hardness of steel bars, quenched in water: contents: 0.37 C, 1.40 Mn, 0.015 P, 0.08 S, 0.17 SI; grain size: 1 to4 Size round in.
mm
‘92
11.7 15.1 SO.8 101.6
I 2 -l Source: Bethlehem
Steel
Surface
Hardness, HRC ‘12radius
l
Sequence
As-Quenched
Hardness
(Oil)
Effect of mass on as-quenched hardness of steel bars, quenched in pdlicontents: 0.37 C, 1.40 Mn. 0.015 P, 0.08 S, 0.17 Si; gram size: 1
Surface
Etardness, ERC ‘/z radius
48 31 28 21
13 ‘8 22 IX
Size round Center
Steels / 221
Rough machine Austenitize Quench Temper Finish machine
Grade I I37 bars and other medium-carbon resulfurized steels are frequently strengthened to desirable levels without quench hardening. Increase the draft during cold drawing by IO to 35% above normal. Stress relieve by heating at approximately 3 I5 “C (600 “F). Produces yield strengths of up to 690 MPa (100 ksi) or higher in bars up to about 19.05 mm (0.75 in.) diam. Machinability is very good
l
Processing
Carbon
in. 1.II
I2 -I Source: Bethlehem
mm 12.7 3.4 50.8 I0l.h
Center 42 73 I8 I6
Steel
1137: Hardness vs Tempering Temperature. erage based on a fully quenched structure
Represents
an av-
Resulfurized
Carbon
Steels / 221
1139 Chemical
Composition.
AISI
and UNS:
0.35 to 0.43 C. 1.35 to
1.65Mn.0.040Pmax.0.13to0.20S
Similar
Steels (U.S. and/or
Foreign).
LINS GI 1390; FED QQ-
S-637 (Cl 139); SAE 5103
Characteristics.
Characteristics neat+ parallel with I 137. Carbon and sulfur contents slightly higher. These differences result in slight11 higher as-quenched hardness tas high as -I7 HRC). slightly lower hardenabilit) t because of higher sulfur content), and even better machinability than I 137. Never recommended for welding or forging
Recommended Normalizing.
Heat Treating
Not usually
required.
Practice
If necessary, heat to 900 “C t 1650
“FJ. Cool in air
Hardening. Heat to 8-tS ‘C t IS55 “FL Flame hardening and carbomtridmg are suitable surface hardening processes. Quench in water or brine. For full hardness. oil quench sections not exceeding 9.525 mm (0.375 m.) thick Tempering.
As-quenched hardness of approximately ness can be reduced bq tempering
Strengthening
Heat to 885 “C t I675 “FL Furnace cool to 650 ‘C t 17-00 “FL at a rate not to exceed 28 “C (SO ‘Fj per h
Hard-
and Stress Relieving.
Grade II39 bars and other medium-carbon resulfurired steels are frequentl) strengthened to desirable Ie~els \\ithout quench hardening. Increase the draft during cold drawing by IO to 35% above normal. Stress relirbe b> hsatntg at approsunatel) 315 “C (600 “F). Produces yield strengths of up to 690 hlPa (,I00 ksit or higher in bars up to about 19.05 mm to.75 In.) dinm. hlachinability is ~2t-y good
Recommended l l l
Annealing.
by Cold Drawing
47 HRC.
l l
Rough machine r\ustsnitize Quench Temper Finish machine
Processing
Sequence
222 / Heat Treater’s
Guide
1139: Hardness vs Tempering Temperature. Represents an average based on a fully quenched
structure
222 / Heat Treater’s
Guide
1140 Chemical
Composition.
AISI and UNS: 0.37 to 0.44 C, 0.70
to
I .OOMn, 0.040 P max. 0.08 to 0. I3 S
Similar
Steels (U.S. and/or
S-637(Cl 140); SAE 5403. J412. 35 MF 4; (Swed.) SSt4 1957
Foreign). UNS G11400; FED QQJ-113; (Ger.) DIN 1.0726; (Fr.) AFNOR
Hardening. Heat to 835 ‘C ( IS55 “FL Flame hardening and carbonitriding are suitable surface hardening processes. Quench in water or brine. For full hardness, oil quench sections not exceeding9.525 mm (0.375 in.) thick Tempering.
As-quenched hardness of approximately ness can be reduced by tempering
50 HRC.
Hard-
Strengthening
Characteristics.
Slightly higher carbon range, compared with I 139. of no practical significance. Hardenability is lower because of lower manganese content. Otherwise, same characteristics as I I37 and I 139, including response to abnormal drafts in cold drauing and a subsequent stress relief. Not used where forging or welding is involved. Machinability is excellent
Recommended Normalizing.
Heat Treating
Not usually
required.
Practice
If necessary. heat to 900 “C ( 1650
“F). Cool in air
by Cold Drawing and Stress Relieving. Grade 1140 bars and other medium-carbon resulfurized steels are frequently strengthened to desirable levels without quench hardening. Increase the draft during cold drawing by IO to 358 above normal. Stress relieve by heating at approximately 3 IS “C (600 “F). Produces yield strengths of up to 690 MPa (100 ksi) or higher in bars up to about 19.05 mm (0.75 in.) diarn. Machinability is very good
Recommended l l l
Annealing.
Heat to 885 “C ( I625 “F). Furnace cool to 650 “C ( 1200 “F). at a rate not to exceed 28 “C (50 “F) per h
l l
Processing
Sequence
Rough machine Austenitize Quench Temper Finish machine
1140: Hardness vs Tempering Temperature. erage based on a fully quenched structure
Represents
an av-
222 / Heat Treater’s
Guide
1141 Chemical
Composition.
AISI and UNS: 0.37 to 0.45 C, 1.35 to
I .65 Mn. 0.040 P max. 0.08 to 0. I3 S
Similar
Steels (U.S. and/or Foreign).
A107.A108,A311;FEDQQ-S-637;SAE5403.5412,5411
UNS
GI 1410:
ASTM
Characteristics.
Most widely used medium-carbon resulfurized steel. As-quenched full hardness of approximately 52 HRC, when carbon is near high side of the range. Slightly lower hardness for middle or lower end of the range. High manganese content imparts higher hardenability compared with I I-IO, but almost the same as I 139. Available in pretreated condition.
Resulfurized Subjected to abnormally heavy drafts followed by stress relieving. grade I 137.) Never recommended for forging or welding
Recommended Normalizing.
Heat Treating
Not usually
required.
(See
Practice
If necessary. heat to 885 “C (I 615
1141
As-Quenched
Hardness
Carbon
Steels / 223
(Oil)
Effect of mass on as-quenched hardness of steel bars, quenched in oil; contents: 0.39 C, 1.58 Mn, 0.02 P, 0.08 S, 0.19 Si; grain size: 90%, 2 to 4; 1 O%, 5
“FJ. Cool in air
Annealing.
llsually purchased by fabricator in condition for machining. If required. may be annealed by heating to 835 “C ( I555 “F). Furnace cool to 650 “C ( IXIO “F) at a rate not to exceed 28 “C (50 “F) per h
Size round in.
mm
‘/: 1 2 4
12.7 ‘5.4 SO.8 101.6
Hardening. Austenitize at 830 “C (IS?5 “F). Flame hardening. carbonitriding, and martempering are suitable processes. Quench in water or brine. For full hardness. oil quench sections under 9.525 mm (0.375 in.) thick Tempering.
Depending upon precise carbon content. as-quenched hardness is usually 48 to 52 HRC. Hardness can be reduced by tempering
Recommended l l l l l
Rough machine Austenitize Quench Temper Finish machine
Processing
Sequence
Source: Bethlehem
Surface 52 18 36 27
Eat-does, ERC ‘4 radius 49 43 28 22
based
46 38 22 18
Steel
1141: Hardness vs Tempering Temperature. Represents erage
Center
on a fully quenched
structure
an av-
Resulfurized
Carbon
Steels / 223
1144 Chemical
Composition. AISI and IJNS: 0.10 to 0.38 C. I.35 to I .65 Mn. 0.040 P max. 0.2-I to 0.33 S
brim. For full hardness, 10.375 in.) thick
Similar
Tempering.
Steels (U.S. and/or Foreign).
UNS
GI 14.40;
ASTM
A108.A311:FEDQQ-S-637(CII~?);SAEJ403.J41?.J413
Characteristics. Special-purpose grade. Very high sulfur content. equal to free-machining 1213. permits extremely fast machining with heavy cuts. Machined fmishes unusually good. High sulfur content reduces transverse impact and ductility. Can be drawn by heavy drafts at elevated temperature, 370 “C (700 “F). which results in relatively high strength and high hardness. up to 35 HRC. Machinability is excellent. Widely used for producing machined parts put in service without heat treatment. Can be purchased in cold drawn condition and heat treated. Depending upon precise carbon content, as-quenched and fully hardened I I44 should be approximately 52 to 55 HRC. Never used I$ here forging or welding is involved
Recommended Normalizing.
Heat Treating
Seldom required.
Annealing.
Seldom necessary. May be annealed by heating to 845 “C ( I555 “F). Furnace cool to 650 “C ( I200 “F), at a rate not to exceed 28 “C (SO “F) per h
Hardening.
sections
less than 9.525
mm
Depending upon precise carbon content, as-quenched hardness of usually 52 to 55 HRC. Hardness can be reduced by tempering
Recommended l l l l l
Processing
Sequence
Rough machine Austenitize Quench Temper Finish machine
1144:
As-Quenched
Hardness
(Oil)
Effect of mass on as- uenched hardness of steel bars quenched in oil. contents: 0.46 C, ? .37 Mn, 0.019 P, 0.24 S. 0.05 hi; grain size: 75+/o, 1 to 4; 25%, 5 to 6
Practice
If necessary. heat to 885 “C ( I625 “FL
Cool in air
carbonitriding
oil quench
Austenitize at 830 “C (I 525 “F). Flame hardening and are suitable surface hardening processes. Quench in water or
Size round
ill.
mm
Surface
‘/J
12.7 25.4 50.8 101.6
39 36 30 27
I 2 1
Source: Bethlehem Stzcl
Hardness, ERC ‘/r radius 32 29 27 .._
1:: 98
Center 28 23 22 __
1:: 97
224 / Heat Treater’s
Guide
1144: Hardness vsTempering Temperature. Represents an average based on a fully quenched
structure
224 / Heat Treater’s
Guide
1146 Chemical
Composition.
AISI and UNS: 0.X
to
0.49 c. 0.70 to
I .OO Mn. O.O-tO P max. 0.08 to 0. I3 S
Similar
(U.S. and/or Foreign).
Steels
UNS GI 1460; FED QQ-
S-637 (Cl 136): SAE J-103, J-tl?. J-II-t; tGer.) DIN 35 MF 1; (Swed.) SSt4 1973
1.0727; (Fr.) AFNOR
Annealing.
Seldom required by the fabricator. If necessary, heat to S-0 “C ( I SSS “F). Furnace cool to 650 ‘C ( 1200 “F) at a rate not to exceed 28 “C (SO ‘F) per h
Hardening. Austenitire at 830 “C ( IS25 “FL Flame hardening, carbonitriding, austemperinp. and mar-tempering are suitable processes. Quench in water or brine. For full hardness. oil quench sections less than 9.525 mm (0.375 in.) thick
Characteristics. An I I-IO with higher carbon. Excellent machinability and relatively low hardenability. Amenable to strengthening by heavy drafts and stress relieving. Higher carbon, lower manganese. and lower hardenability make it popular for induction hardening. Never use uhen forging or welding is involved. Can be quenched and tempered. Asquenched hardness of 55 HRC or slightly higher. depending on carbon content
Tempering.
Recommended
l
Heat Treating
Practice
nrss is usually recommended
Martempering.
Cool in air
Seldom required.
If necessary. heat to 885 “C ( l62S “F).
Austenitize
at 815 “C ( IS00 “F). Martemper
in oil at
I75 “C (345 “F)
Recommended l l
Normalizing.
Depending upon prectse carbon content. as-quenched hardSS HRC. Hardness can be reduced by tempering. under practice
l l
Processing
Sequence
Rough machine Austenitize Quench Temper Finish machine
1146: Hardness vs Tempering Temperature. Represents an average based on a fully quenched
structure
Resulfurized
Carbon
Steels / 225
1151 Composition.
Chemical
AISI and UNS: 0.48 to 0.55 C, 0.70 10
I .OO Mn, 0.040 P max. 0.08 to 0. I3 S
Similar
Steels (U.S. and/or Foreign).
Al07. Al08. A3ll; FEDQQ-S-637tCllSl): SAEJ403. J4l2, J-II-I
UNS Cl IS IO; ASThl hlILSPEC hlIL-S-30137A;
Characteristics. Resulfurized version of 1050. Carhon ranges the same. Although rhe I I5 I manganese comenl is slightly higher. some of this manganese combines \\iith the high sulfur, so that the hardenabihty is almost the same as 1050. As-quenched hardnesses of 1050 and I I51 are essentially the same. SS HRC or slightly higher. I IS I also used for induction hardening. 1050 used for parts to be forged. I IS I used for parts 10 be machined from bars
Recommended Normalizing. Cool in air
Seldom
Heat Treating used. If necessary,
Practice heat to 870 “C ( 1600 “F).
Annealing. Heat IO 870 “C ( 1600 “F). Furnace 81 a rate not to exceed 28 “C (50 “F) per h
cool
IO
650 “C ( 1200 “F)
Hardening. Austenitize 31 830 “C ( 1525 “F). Flame hardening, induction. and carbonitriding are suitahle surface hardening processes. Quench in nater or brine. Oil quench sections under 6.35 mm (0.25 in.) thick Tempering erly austenitizcd
After Hardening. and quenched.
Recommended l l l l l
Hardness of at least 55 HRC. if propHardness can be adjusted by tempering
Processing
Sequence
Rough machine Austenilize Quench Temper Finish machine
1151: Hardness vs Tempering Temperature. erage based on a fully quenched structure
Represents
an av-
1151: Microstructure. 2% nital, 500x. Manganese sulfide stringers (black) in steel bar. Remainder is dispersion of spheroidized carbide in ferrite matrix. Micrograph is cross section, taken perpendicular to rolling direction
1211 Chemical Composition.
UNS GlZllOand
AlSI/SAE
1211: 0.13 C
max. 0.60 to 0.90 Mn. 0.07 to 0.12 R 0. IO to 0. IS S
Similar Steels (U.S. and/or Foreign).
ms
G I?. I IO;
ASTM
AlO7.Al07(BIIII),Al08.Al08(BIIII);FEDQQ-S-637(Cl2ll);S~ 5403
Characteristics.
Machinery steel that has been resulfurized and rephosphorized has better machinability than that of grade I I IO. Furnished in hot rolled or hot rolled and cold drawn condition. The latter condition is
the better for machinability. Intended for fabrication recommended for forging. cold forming, or welding
Recommended
Heat Treating
Normalizing and Annealing. Light Case Hardening. bath nitriding
process described
by machining.
Never
Practice
Seldom required
hlay be desired. See carbonitriding for 1008
and salt
1212 Chemical
COIIIpOSitiOn. UNS and SAE/AISI: 1.00 Mn, 0.07 to 0.12 P. 0. I6 to 0.23 S
Similar
0.13 C max. 0.70 to
Steels (U.S. and/or
D; ASTM A107. Al07 (Cl212);SAEJ403;(Ger.)
Foreign). LJNS G 12 120; AMS 5010 (81212). A108. Al08 (Bl212); FED QQ-S-637 DIN I.071 I:(ltal.) LINI IOS ZO;(Jap.)JISSLJM
21
Characteristics. Similar tents are higher. Machinability
to 121 I, except sulfur and manganese conbetter than that of I2 I I. Adverse effects of
sulfur and phosphorus greater
Recommended Normalizing
on mechanical
Heat Treating
and Annealing.
Light Case Hardening. bath nitriding
and fabrication
process described
properties
are slightly
Practice
Seldom required
May he desired. See carbonitriding for 1008
and salt
1213 Chemical
COtnpOSitiOn. UNS and SAE/AISI: I.00 Mn, 0.07 to 0.12 P. 0.2-t to 0.33 S
0.13 C max. 0.70 to
Similar
Steels (U.S. and/or Foreign). UNS G 12 I 30: ASME Al07,Al07(BlIl3j,Al08.AIO8(BIll3);FEDQQ-S-637(Cl9l3);SAE J403; (Ger.) DIN I .0715; (Ital.) UNI 9 SMn 23: (Jap.) JIS SUM 22: (U.K.) B.S. 220 M 07 Characteristics. Nearly identical sulfur further enhances machinability fabrication properties
to those of I2 12. Greater content of at the sacrifice of mechanical and
Recommended Normalizing
Heat Treating
and Annealing.
Light Case Hardening. bath nitriding
process described
Practice
Seldom required
May be desired. See carbonitriding for 1008
and salt
Rephosphorized
and Resulfurized
(1200 Series) / 227
12l.14 Chemical Composition.
UNS and SAE/AISI: 0. I5 C max. 0.85 to I. I5 Mn. 0.04 to 0.09 P. 0.26 to 0.35 S. 0. I5 to 0.35 Pb
Similar Steels (U.S. and/or Foreign). UNS Gl214-k A107, Al08; SAE 5403, J412, J414; (Ger.) DIN 1.0718; (Ital.) SMnPb 23; (Jap.) JIS SUM 22 L. SUM 24 L; (Swed.) SS)4 1913 Characteristics.
ASTM UNI 9
Contains a lead addition of 0. I5 to 0.35% indicated by L in designation. Represents the ultimate in free-machining characteristics. but an even further sacrifice of mechanical and fabricating properties. such as forgeability. cold formability, and weldability. Addition of
lead further enhances machinability in terms of high speeds with heavy cuts and provides excellent finishes on machined surfaces. Sometimes saves an extra machining operation
Recommended
Heat Treating
Normalizing and Annealing. Light
Case
bath nitriding
Hardening. process described
Practice
Seldom required
May be desired. See carbonitriding for I008
and salt
Rephosphorized
and Resulfurized
(1200 Series) / 227
1215 Chemical
COIIIpOSitiOn. UNS and SAE/AISI: I.05 Mn. 0.04 to 0.09 P. 0.26 to 0.35 S
Similar
Steels (U.S. and/or Foreign).
0.09 C max. 0.75 to
UNS Gl~lso;
FED QQ-
S-637: SAE J4 12
Characteristics.
Compared with I?. 13. with minor adjustments in carbon, manganese, phosphorus. and sulfur contents. No major effects on mechanical or fabricating properties. Represents another free-machining
steel. Commonly used for parts completed in automatic multispindle machine tools
Recommended Normalizing
Heat Treating
and Annealing.
Practice
Seldom required
Light Case Hardening. May be desired. See carbonitriding and salt bath nitriding process described for 1008
1215: Microstructures. (a) As polished (not etched), 1000x. Cold drawn steel tube. Longitudinal view. Segmented polished (not etched), 1000x. Cold drawn steel tube, at lower magnification. Sulfide inclusions shown
sulfide inclusion. (b) As
High
Manganese
Carbon
(1500
Steels
Series)
1513 Chemical
Composition. MS1 I .-IO Mn. 0.040 P max. 0.050 S max
Similar
Steels (U.S. and/or
and UNS:
Foreign).
0.10 to 0.16 C. I. IO
UNS G
to
IS 130; SAE J-103.
J-II2
Characteristics.
Essentially the high-manganese version of 1012. However. the higher manganese content provides slightly greater strength in the normalized or annealed condition and some\< hat better core properties when case hardened. Excellent forgeability and weldabili?. Rsasonably good cold formability, only slightly less than IO1 2. hlachmability is very poor when compared with the II00 and 1200 grades. Generally avarlable in wrious product forms. includinp flat stock. bars. and forging stock
Forging. Heat to approximately 1290 “C (2355 “F). Finish forging fore temperature drops bclou 925 “C t 1695 “F)
Recommended Normalizing.
Heat Treating
Heat to 885 T
be-
Practice
t 1625 “F). Cool in still air
Annealing.
For clean surfaces. heat to approxmlately 885 “C (163-S “F) in lean exothermic atmosphere. Cool in cooler section of continuous furnace
Case Hardening. Carbonitride at 760 to 870 “C (1400 to 1600 “F) in an enriched sndothemtic carrier gas. plus ahout 10% anhydrous ammonia. Case depths from 0.076 to 0.26 mm (0.003 IO 0.01 in.). Oil quench directly from carbonitriding temperature. Pro\ ides maximum surface hardness. Salt baths can produce similar results
1582lH, Chemical
15821RH
COWpOSitiOn.
15BZlH.
UNS H15211 and SAE/AISI:
0.17 to 0.74 C. 0.70 to 1.10 hln. 0. IS to 0.35 Si. t0.0005 to 0.003 B can be expected). SAE 15B21RH: 0.17 to022 C.O.80 to 1.10 hln.0.15 too.35 Si (0.0005 to 0.003 B can be expected)
Similar
Steels (U.S. and/or
SAEJl168.51868:
Foreign).
15BZlH.
UNS H IS2 I I :
(Ger.) DIN 1.5513: ASTh1Yl-l
Characteristics. Nonfree machining steel. Can be cold formed to some degree. Readily weldable. When carbon IS on the high side and with the higher manganese and addition of boron. a combination can exist where some preheating prior to welding is necessary to avoid weld crackng. Combination of higher manganese and boron provides whstantial increase in hardenabilit), compared with 1020
Annealing.
Excellent forgeahilitj. below 925 “C ( 16% “F)
Heat to I260 “C (1300 ‘F). Do not forge
Heat Treating
Tempering. some sacrifice
l
l
l l
Normalizing.
Heat to 925 “C ( 1695 “FL Air cool
in the
Optional. Temper at ISO “C (300 “F) for I h or higher if of hardness can be tolerated
Recommended l
l
Practice
preferably
Can he case hardened bj an! one of several processes. from light case hardening h) carhonitridinp and salt bath nitriding described for grade IO08 to deeper case carhuriring in gas. solid. or liquid media. Because of higher hardenahility. oil quench thicker sections for full hardness. Carburize and quench as for 1020
l
Recommended
“F). Cool slo~lp.
Hardening.
l
Forging.
Heat to 870
furnace
l
Processing
Forge Normalize Roy! machine Semltlnish machine and grind Carburize Diffusion c>cIe Quench Temper Finish grind
Sequence
High Manganese
15B21H: Hardenability Curves. Heat-treating “C (1700 “F). Austenitize: 925 “C (1700 “F)
Hardness purposes J distance, mm
Hardness purposes J distance, ‘/,6 ill. 1 1,s ? 3 3 3s 4 4.5 i.s 5 55 7 7.5 3 9
limits for specification Hardness, hlaximum
HRC hlinimum
limits for specification Hardness, Masimum
HRC hlinimum 41 -II -IO SY 38 36 30 13 20
temperatures
recommended
Carbon
Steels (1500 Series) / 229
by SAE. Normalize (for forged or rolled specimens
only): 925
1
230 / Heat Treater’s
Guide
15621RH: Hardenability “C (1700 “F). Austenitize-
Hardness purposes J distance, %a in. I 2 3 4 5 6 7 8 9 IO II 12 13 I4 IS 16 I8 20 22 24 26 28 30 32
Hardness purposes J distance. mm I.5 3 5 7 9 II 13 IS 10 15 30 35 lo 1s
Curves. Heat-treating 925 “C (1700 “F)
limits for specification Hardness, Maximum
ARC Minimum
47 46 44 43 37 30 24 22 20
42 II 39 33 24 20
limits for specification Hardness, Maximum 41 46 44 40 32 24 22 20
HRC Minimum 42 II 38 29 21
temperatures
recommended
by SAE. Normalize for forged or rolled specimens
only: 92:
High Manganese
Carbon
Steels (1500 Series) / 231
15821 H: Hardness vs Tempering Temperature. average based on a fully quenched structure
15B21H: End-Quench Dktance frum quenched surface &in. mm
I I .s 2 2.5 3 3.5 4 4.5 5
I.58
2.37 3.16 3.95 4.1-l 5.53 6.32 1.11
7.90
Hardenability
Hardness, HRC min max
18 48 -1-l 4-l -I6 -Is 4-l 42 40
-II 41 -IO 39 38 36 30 23 20
Distance from quenched surface mm ‘/,a in.
6 6.5 1 1.5 8 9 IO I2 I-1
Eardness, HRC max
9.48 10.27
35 32
II.06 II.85 12.64 l-l.22 IS.80 18.96 22.12
27 22 20
Represents
an
High Manganese Carbon Steels (1500 Series) / 231
1522,1522H Chemical Composition.
1522. AI.9 and UNS: 0.18 to 0.21 C. I. IO to 1.40 h4n. 0.040 P max. 0.050 S max. 1522H. UNS H15220 and SAE/AISI 1522H: 0.17 to 0.25 C. I .OO to I SO Mn. 0. IS to 0.35 Si
Recommended
Similar Steels (U.S. and/or Foreign). 1522. UNS G 15220:
Annealing.
J403, J412. 15228. UNS HI5220; SAE Jl268: UNI G 22 Mn 3; (Jap.) JIS SMnC 21
furnace
(Ger.) DIN
SAE 1.1133: (Ital.)
Normalizing.
Heat Treating
Practice
Heat to 92s “C t 1695 “F). Air cool Heat to 870 “C t 1600 “F). Cool slowly,
preferably
in the
Hardening.
Characteristics.
Represents the principal carburizing grade of the I SO0 series. Characteristics similar to I SB2 I H. Nominal manganese content is higher which increases hardenability to a considerable extent. However. contains no boron. As a result, hardenability bands are not .greatl! different for steels ISBZIH and lS22H. Weldability and forgeability are good
Forging. Heat to I260 “C (2300 “F). Do not forge below 925 “C t 1695 “F). For lS22H. drop forge from 900 to I250 “C (I650 to 2380 OF)
Can be case hardened b) any one of several processes. from light case hardening by carbonitriding and salt bath nitriding described for grade 1008 to deeper case carburizing in gas. solid. or liquid media. See carhurizing process described for grade 1020. For lS22H. use carburizing temperature of 900 to I250 “C t I650 to 2280 “F). Use oil for cooling medium. Because of higher hnrdenabilib. thicker sections can be oil quenched for full hardness
Tempering. some sacrifice
Optional. Temper at IS0 “C (300 “F) for I h or higher if of hardness can be tolerated
232 / Heat Treater’s
Recommended l l l l l l l l l
Guide
Processing
Sequence
1522, 1522H: Hardness vs Tempering Temperature. sents an average based on a fully quenched structure
Forge Nomlalize Rough machine Semifinish machine and grind Cxburize Diffwion cycle Quench Temper Finish grind
1522H: End-Quench Distance from quenched surface l/j6 in. mm I 1.5 2 2.5 3 3.5 -I 4.S 5 5.5
I.58 2.37 3.16 3.95 4.7.l s.s3 6.32 7.1 I 7.90 8.69
Hardenability Eardness, HRC max min
so -18
JI 41
17 46 1.5 -12 39 37 3-l 32
32 27 22 21 70 .,.
Distance from quenched surface ‘ii6 h. mm 6 6.5 7 7.5 8 9 IO 12 I-I I6
9.48 IO.27 I I.06 II58 126-l l-1.22 IS.80 18.96 Z’.II ‘5 ‘Y __.-
Hat-dries. HRC max 30 28 27 __. 25 23 22 20
Repre-
High Manganese Carbon Steels (1500 Series) / 233
1522H: Hardenability Curves. Heat-treating temperatures (1700 “F). Austenitize:
925 “C (1700 “F)
Hardness limits for specification purposes J distance, mm
Eardness, Maximum
ARC hlinimum
Hardness limits for specification purposes I distance, ‘/,6 in. I I.5 3 !.5 3 3.5 + 4,s
i.5 5 i.S
Hardness, Maximum SO 48 17 16 -IS 12 39 37 3-l 32 30 28 27
HRC hlinimum
recommended
by SAE. Normalize (for forged or rolled specimens
only): 925 “C
1
234 / Heat Treater’s
1522: Continuous
Guide
Cooling Transformation
Diagram. A British steel with a chemical composition roughly equivalent to 1522: 0.19 C, 1.20
Mn, 0.020 P, 0.020 S, 0.20 Si. Hot rolled and austenitized
at 870 “C (1600 “F)
234 / Heat Treater’s
Guide
1524,1524H Chemical
Composition. 1524. AISI and UNS: 0.19 to 0.25 C. I.35 to 1.65 Mn, 0.040 P max. 0.050 S max. 15248. UNS H15240 and SAE/AISI 1524H: 0.18 to 0.26 C, I .2S to I .7S Mn. 0. I5 to 0.35 Si: 152-I was formerly
Similar
designated
Foreign).
1524:
UNS
G15240:
ASTM A510, AS13 (1023). A519. AS-45: SAEJ403.J312,J414:(W. DfN I. I 160. 1524H. UNS H 15210: SAE J 1268; (Ger.) DfN I. I I60
Ger.)
Characteristics.
Essentially a higher manganese version of 1023. Has higher hardenability. Grade lS24H is now available with a guaranteed hardenability band. Considered a borderline grade because it can be case hardened by carburizing or carbonitriding. Popular for this purpose because of relatively high core hardness. This permits use of thinner cases, which conserve thermal energy and decrease processing cost. I524H also used in the hardened and tempered condition where moderate strength is needed. As-quenched hardness of43 HRC or slightly higher can be expected. Even though the carbon content is only 0.26 max. welding must be done with care. because the high manganese may raise the carbon equivalent to a dangerous degree unless preheating and postheating practices are used. Forgeability is excellent. Grade lS21H may be obtained in various product forms
Practice
Direct Hardening. brine. Quenchant
Tempering. by tempering.
Heat to 1215 ‘C (2275 “F). Do not forge below 900 “C ( 1650 “F). For lS24H. drop forge between 900 to I250 “C ( I650 to 2280 “F)
Austenitize at 885 “C (1625 “F). Quench in oil or depends on section thickness
As-quenched as required
hardness of 43 HRC or higher can be reduced
Case Hardening. Can be case hardened by any one of several processes. from light case hardening by carbonitriding and salt bath nitriding described for grade 1008 to deeper case carburizing in gas. solid, or liquid media. Plasma (ion) carburizing is an alternative process. (See carburizing process described for grade 1020). For 1524H. use carburizing temperature of 900 to 925 “C ( I650 to I695 “F). Use oil for cooling medium
Recommended l l l l l
Forging.
Heat Treating
Heat to 925 “C ( I695 “FL Cool in air
Annealing. Heat to 900 “C ( I650 “FL Furnace cool to 675 “C ( I245 “F) at a rate not to exceed 28 “C (SO “F) per h
as IOXX grade
Steels (U.S. and/or
Recommended Normalizing.
l l
Normalize Anneal Rough machine Austenitize Quench Temper Finish machine
Processing
Sequence
High Manganese
1524: Continuous Cooling Transformation
at 870 “C (1600 “F)
1524H: End-Quench Hardenability from
quenched s&ace 916 in. mm
Distance El~dlleSS.
ERC max
min
ti-om
quenched surface ‘/,6 in. mm
Elardness. ERC max
I 1.5
I.58 2.37
51 49
42 42
6 6.5
918 10.27
32 30
2 2.5
3.16 3.95
18 41
38 3-l
7 7.5
II.06 I I.58
29 28
3 3.5 4 4.5 5 5.5
1.74 5.53 6.32 7.1 I 1.90 8.69
15 43 39 38 35 34
29 35 ‘2 20
12.6-I 14.71 IS.80 18.96 22. I? 25.28
27 26 25 23 22 20
8 9 IO I? I-l I6
Steels (1500 Series) / 235
Diagram. A British steel with a chemical composition roughly equivalent to 1524: 0.19 C, 1.50
Mn, 0.020 P, 0.020 S, 0.20 Si. Hot rolled and austenitized
Distance
Carbon
236 / Heat Treater’s
Guide
1524, 1524H: Hardness vs Tempering Temperature. Represents an average based on a fully quenched structure
1524: Microstructure.
Picral and mtal, 500x. Sheet, 3.175 mm (0.125 in.) thick. Austenitized at 1095 “C (2005 “F). Cooled in air. Dark areas are fine pearlite with some bainite. Light areas are envelopes of ferrite at prior austenite grain boundaries and Widmanstatten platelets of ferrite within grains
1524: Plasma (Ion) Carburizing. Carbon concentration profiles in AISI 1524 steel after ion carburizing for 15 min at 1050 “C (1920 “F) in atmospheres and with flow conditions indicated
High Manganese
1524H: Hardenability
Curves. Heat-treating
(1650 “F). Austenitize:
870 “C (1600 “F)
iardness wrposes I distance, urn .5 / 1 , I I 3 5 10 15
iardness w-poses distance.
‘16io. .s .s ._5 .5 ._5 5
limits for specification Eardness, Maximum
HRC Minimum
51 19 4-l 38 3-l 30 ‘7 2s 13
42 39 26 21
limits for specification Eardness. Maximum 51 49 48 47 45 43 39 38 3s 34 32 30 29 28 27 26 25 23 22 20
HRC hlinimum 42 42 38 34 29 25 22 20
temperatures
recommended
Carbon
Steels (1500 Series) / 237
by SAE. Normalize (for forged or rolled specimens
only): 900 “C
238 / Heat Treater’s Guide
1526,1526H Chemical Composition.
1526. ALSI and UNS: 0.22 to 0.29 C. I. IO
to I .-IO Mn, 0.040 P max. 0.050 S max. 15268. UNS H15260, SAE/AISI 15268: 0.21 to 0.30 C, 1.00 to I.50 Mn. 0. I5 to 0.35 Si
Similar Steels (U.S. and/or Foreign). 1526:
UNS GlS260; ASTM A5 IO; SAE J403. J-l 12: (Ger.) DfN I. I I6 I ; 15268. UNS H 15260:
SAE Jl268 Considered a borderline grade because it can be case hardened by carburizing or carbonitriding. Popular for this purpose because of relatively high core hardness. This permits use of thinner cases, which conserve thermal energy and decrease processing cost. I526H also used in the hardened and tempered condition where moderate strength is needed. As-quenched hardness of 43 HRC or slightly higher can be expected. Even though the carbon content is onlv 0.26 max. welding must be done with care, because the higher manganese may raise the carbon equivalent to a dangerous degree. unless preheating and postheating practices are used. Forgeability is excellent. Grade l526H may be obtained in various product forms
Forging.
Heat to I235 “C (2275 “F). Do not forge below 900 “C ( I650 “F). For I526H. drop forge between I205 to 850 ‘C (2200 to 1560 “F)
Normalizing.
Heat Treating
Heat to 925 “C (I695
1526: Continuous
Direct Hardening. brine or oil. Quenchant hardness
Tempering.
Characteristics.
Recommended
Annealing. Heat to 900 “C ( I650 “F). Furnace cool to 675 “C ( 1245 OF) at a rate not to exceed 28 “C (SO “F) per h
Cooling
Practice
“F). Air cool
Transformation
Mn, 0.020 P, 0.020 S, 0.20 Si. Hot rolled
by tempering,
Diagram.
As-quenched as required
hardness of 43 HRC or higher can be reduced
Case Hardening. Can be case hardened by any one of several processes. from light case hardening by carbonitriding and salt bath nitriding described for grade 1008 to deeper case carburizing in gas. solid. or liquid media. See carburizing process described for grade 1020. For 15268, use carburizing temperature of 900 to 925 “C ( I650 to 1695 “F). Use oil for cooling medium Recommended l
Processing
Anned
l
Rough machine Austenitize (or case harden) Quench Temper Finish grind
l l l
Sequence
Normalize
l
l
and austenitized
Austenitize at 885 “C (I625 “F). Quench in water, will depend on section thickness and required
A British steel with a chemical at 870 “C (1600 “F)
composition
roughly
equivalent
to 1526: 0.28 C, 1.20
High Manganese
1526H: Hardenability Curves. Heat-treating (1650 “F). Austenitize:
Hardness purposes I distance, mm
1.5 3 5 7 1 11 13 15 20
iardness wrposes distance, 46 in.
.5 !.5 1.5 1.5 i.5 i i.5 1.5 1
0 .2 i4
16 18
870 “C (1600 “F)
limits for specification Hardness, Maximum
ARC hlinimum
53 50 44 37 32 28 25 24 .
44 39 24 20 . . . .
limits for specification Hardness, Maximum
53 50 49 47 46 42 39 37 33 31 30 28 27 26 26 24 24 23 22 21 20
ERC
hfinimum 44 42 38 33 26 25 21 20
.
..
.
temperatures
recommended
Carbon
Steels (1500 Series) / 239
by SAE. Normalize (for forged or rolled specimens
only): 900 “C
240 / Heat Treater’s
Guide
1526, 1526H: Hardness vs Tempering Temperature. Represents an average based on a fully quenched structure
1526H: End-Quench Hardenability Distance from quenched surface ‘46in. mm I I.5 z 2,s 3 3.5 -I 4.5 5 5.5 6
1.58 2.37 3.16 3.95 1.7-l 5.58 6.37 7.1 I 7.90 8.69 9.48
Hardness, HRC mia may 53 so 49 17 46 -12 39 37 33 31 30
4-t 11 38 33 26 25 21 20
Distance from quenched surface 1,,,6 in. mm 6.5 7 7.5 8 Y 10 12 II 16 18
IO.27 I I.06 I I .8S 12.6-I l-l.22 IS.80 lg.96 22.12 2s 18 28.44
Hardness. HRC mar 28 ‘7 xi 26 2-l 21 23 22 21 20
240 / Heat Treater’s
Guide
1527 Chemical
Composition. AISI and UNS: 0.32 to 0.29 C. 1.20 to I SO hln. 0.040 P max. 0.050 S max. UNS Cl5270 and AISI/SAE 1527: Standard composrtion range for manpanese IS I.20 to I.55 hln: uas formerly designated as I OXX grade Similar
Steels (U.S. and/or Foreign).
A510.A513(1027);SAE5403.J-!12:(Ger.)DIN
UNS ~15270: I.1161
Kr-hl
Characteristics.
Considered a borderline grade because tt can be case hardened bq carburizing orcarbonittiding. Popular for this purpose because of relatively high core hardness. This pemtits use of thinner cases. u hich consene thermal energy and decrease processing cost. IS27 also used in the hardened and tempered condition IShere moderate strength is needed. As-quenched hardness of-13 HRC or slightly higher can be expected. Even though the carbon content IS onJ> 0.29 mas. itelding must be done with care. because the higher manganese may raise the carbon equivalent to a dangerous degree. unless preheating and postheating practices are used. Forgeability is excellent. Grade IS37 ma> be obtained in various product forms
Forging.
Heat to IX5
C (2275 “Ft. Do not forge beIon about 900 “C
(16S0°F,
Annealing. Heat to 900 “C ( I650 “F). Furnace cool to 675 ‘C ( I235 “F) at a rate not to escsed 28 “C (SO ‘F) per h Hardening. Can be case hardened b! any one of several processes. from light case hardening by carbonitriding and salt bath nitriding described for grade 1008 to deeper case carburizinp in pas. solid. or liquid media. (See carburizinp process described for pads 1020). For lS22H. use carburizing temperature of 900 to 925 “C (I650 to I695 “F). Use oil for cooling medium Direct Hardening. Austenitize at 885 “C t 1625 “F). Quench in oil. Uater or brine. Quenchant will depend on section thickness and required hardness Tempering. by tempering
Recommended
Heat Treating
Practice
Normalize
l
XMGll
l
Rough machine Austenitize (or case harden) Quench Temper Finish machine
l l
Normalizing.
Heat to 925 “C (I695
“F). Cool in air
Processing
l
l
Recommended
As-quenched hardness of 43 HRC or higher can be reduced as required (see tune)
l
Sequence
High Manganese
Carbon
Steels (1500 Series) / 241
1527: Hardness vs Tempering Temperature. Represents average based on a fully quenched
structure
an
High Manganese
Carbon
Steels (1500 Series) / 241
15B28H Chemical
Composition.
025 to0.31C. expected)
Similar
15BZSH. UNS H15281 and SAE B28H: l.OOto 1.50Mn.0.15 to0.3.5Si.~O.OOOS to0.003 Bcnn be
Hardening.
Steels (U.S. and/or Foreign).
Curves. Heat-treating
“C (1650 “F). Austenitize:
870 “C (1600 “F)
I distance, nm 5
II 3 5 !O !5 !O i5 Lo IS i0
Heat Treating Practice
Clubonitriding
is a suitrlbk surface hardening process
WE 51X8; AST~I ~304
15828H: Hardenability iardness wrposes
Recommended
temperatures
recommended
by SAE. Normalize (for forged or rolled specimens
only): 900
limits for specification Hardness, HRC hlanimum hlinimum 53 53 53 5’ 51 50 18 15 35 29 26 2s 21 23 20
(continued)
242 / Heat Treater’s Guide
15B28H: Hardenability
Curves (continued).
mens only): 900 “C (1650 “F). Austenitize:
Hardness limits for specification purposes J distance, ‘/la in. 1
2 3 4 5 6 7 8 9 10 11
12 13 14 15
16 18 20 22 24 26 28 30 32
-
Earduess, BRC Maximum Minimum 53 53 52 51 51
50 49 48 46 43 40 31 34 31 30 29 27 25 25 24 23 22 21 20
41 41 46
45 42 32 25 21 20
.. . .. ... . .. . . ... .. ...
. ... ... . . ...
Heat-treating 670 “C (1600 “F)
temperatures
recommended
by SAE. Normalize
(for forged or rolled speci-
242 / Heat Treater’s
Guide
15B30H Chemical
Composition.
0.35C.0.70to
Similar
UNS H15301 and SAE 15B30H: 0.27 to l.ZOMn.0.15 to0.35Si~0.0005to0.003Bcanbeexpected)
Steels (U.S. and/or Foreign).
SAE J 1268; ASTM ~30-4
Recommended Hardening.
Heat Treating
Practice
Carbonitriding is a suitable surface hardening process
High Manganese
15B30H: Hardenability
Curves. Heat-treating
“C (1650 “F). Austenitize:
Hardness purposes J distance, mm 1.5 3 5 7 9 11 13 15 20 25 30 35
iardness wrposes I distance, 46in.
L 1
I 0 1 2 3 4 5 6 8 !O
870 “C (1600 “F)
limits for specification Hardness, ARC Maximum Minimum 55 54 53 52 49 45 38 31 26 23 20
48 47 45 38 25 20
. . ... ...
limits for specification Hardness, ARC hlinimum blaximum 55 53 52 51 50 48 43 38 33 29 21 26 25 24 23 22 20
48 47 46 44 32 22 20 . . . .. .. . ... .. . . .. .. .
temperatures
recommended
Carbon
Steels (1500 Series) / 243
by SAE. Normalize (for forged or rolled specimens
only): 900
244 / Heat Treater’s
15B35H,
Guide
15B35RH
Chemical Composition. CJNS HI5351 and SAE/AISI 158358: 0.31 toO.39C.0.70to 1.20hln.0.15 to0.3SSi,~0.000Sto0.003Bcanhs expected). SAE 15B35RH: 0.33 to 0.38 C. 0.80 to I.10 Mn. 0.15 to 0.25 Si’(O.OOOS to 0.003 B can he expected) Similar
Steels (U.S. and/or
WE Jl268.Jl868: ASThl J 1868; ASThl A9 I-l
A914.
Foreign). lSB35RH.
15B35H. LJNS H IS35 I ; l!NS HlS3Sl; SAE 51268.
Characteristics.
Excellent forgability. Special qualit) grades for cold heading. cold forging. and cold estnwion. Can he welded. Because of c&on content. preheating and posthenting are required and interpass temperature must be controlled. Machinability on14 fair. Wide range of mechanical properties can be attained by quenching and tempering. Similar to 1035. Higher manganese content and horon addition increase hardenahility
Annealing. Heat to 870 “C ( I600 “‘F). Furnace cool to 650 “C ( I200 “F) at a rate not to esceed 18 “C (50 “F) per h Hardening. Austenitize a1855 “‘C I I575 “F). Cllrbonitriding surface hardking process. Depending on section thicknine& usually oil quenched Tempering.
Heat IO IX5
“C (2275 “F). Do not forge bslo\v 870 “C t I600
“F)
Recommended l l
l l
Recommended Normalizing. 15835H:
Heat Treating
l
Heat to 915 “C i I680 ‘FL Cool in air
End-Quench
Distance from quenched surface ‘/lb in. mm
l
Practice
of approximntsl~
-15 HRC can be reduced
hy
tempering
l
Forging.
Hardness
is a suitable this steel is
l
Forge Nomlalize Anneal (if nccessar) Rough machine Austenitize Quench Temper Finish machine
Processing
Sequence
for machining)
Hardenability Distance from quenched surface 1. ‘16 in. mm
Hardness. HRC mas
I 7 ;
I .5X
13
20.5-l
1.74 S.lb
15 l-l
22. 23.70I?
2b
4 s 6 7 8 Y
6.32 7.90 9 43 I I a6 I2.b-l 11.22
I6 I8 xl 22 2-l 16
25.28 28 44 31 60 31.7b 37 92 11.08
3
IO II I2
IS 80 17.38 18.96
28 30 32
u.2-l
‘0
47.40 SO.56
:.:
ii ‘2
15B35H: Hardness vs Tempering Temperature. average based on a fully quenched structure
Represents
an
High Manganese
Carbon
Steels (1500 Series) / 245
15835H: Microstructures. Microstructures of 15835 steel. (a) In the as-received hot-rolled condition, microstructure is blocky pearlite. Hardness is 87 to 88 HRB. (b) In the partially spheroidized condition following annealing in a continuous furnace. Hardness is 81 to 82 HRB. (c) In the nearly fully spheroidized condition following annealing in a bell furnace. Hardness is 77 to 78 HRB
246 / Heat Treater’s
Guide
15835H: Hardenability
Curves. Heat-treating
“C (1600 “F). Austenitize:
845 “C (1550 “F)
Hardness purposes 1 distance, mm
limits for specification Hardness, ARC Minimum hlaximum 58 51 56 5-l 52 41 39 32 27 25 2-l 23 22 20
iardness wrposes I distance, 116io.
51 50 39 -IS 32 2-l II 20
limits for specification Hardness, HRC hGnimum Maximum 58 56 5s 5-l 53 51 37 II
48 18 39 ‘8 2-l 22
30
30
51 so
I
0 1 2 3 -I S 6 8 10 12 !I :6 :8 80
27 26 2s 24 22 ‘0
temperatures
recommended
by SAE. Normalize
(for forged or rolled specimens
only): 870
High Manganese
Carbon
Steels (1500 Series) / 247
1536 Chemical
Composition.
UNS G15360, SAE/AISI:
I.20 to I.50 Mn. 0.040 P max. 0.050 S max: was formerly grade
0.30 to 0.37 C, designated
IOXX
Recommended Hardening.
Heat Treating
Carbonitriding
Practice
is a suitable surface hardening
process
High Manganese Carbon Steels (1500 Series) / 247
15B37H Chemical Composition.
UNS15371 and SAE/AISI
to 0.39 C, 1.00 to 1.50 Mn, 0.15 to 0.35 Si (0.0005 expected)
Similar Steels (U.S. and/or Foreign).
15B37H: 0.30
to 0.003 B can be
UNS H IS37 I ; SAE J I168
Characteristics. Same characteristics. exceot treater hardenabilitv , than 15B35H because of higher manganese content. Maximum hardness about the same. 15B37H is an oil hardening grade because hardenability equals that of some alloy grades. Excellent forgeability. Fair machinability .
Forging.
Hardening. Austenitize at 855 “C ( I575 “F). Carbonitriding surface hardening process. Quench in oil Tempering.
As-quenched reduced by tempering
Recommended l l l
Normalizing.
Heat Treating
35 HRC can be
L
Heat to I245 “C (2275 “F). Do not forge below 870 “C ( 1600 OF’)
Recommended
hardness of approximately
is a suitable
Practice
l l
Heat to 915 “C (1680 “F). Cool in air
l
Annealing.
Heat to 870 “C ( I600 “F). Furnace cool to 650 ‘C ( IXU “F) at a rate not to exceed 28 “C (50 “F) per h
l l
Processing
Sequence
Forge Normalize Anneal (if necessary for machining) Rough machine Austenitize Quench Temper Finish machine
15837H: End-Quench Hardenability Distance from quenched surface ‘/,ain. mm
Eardness, FIRC max min
Distance from quenched surface 916 in. mm
I
I S8
x3
SO
13
2o.s-I
2 3
3.16 4.74 6.32 7.90 9.48 II.06 12.64 11.22
56 ss S-l 53 52 51 so
SO 49 38 13 37 33 26
l-l IS 16 I8 20 22 2-l 26
22 I2 23.70 ‘5.28 ‘8.44 31.60 31.76 37.92 11.08
IO
IS.80
4s
ii
II
17.38 IS.96
40
21
28 30 32
4-t 26 17.10 SO56
3
S 6 7
8 9
I2
Hardness, ERC max min .., 33 .,, 29
20
27
.._
.._
2s 23
1:: 21
15B37H: Hardness vs Tempering Temperature. Represents average
based
on a fully quenched
structure
an
248 / Heat Treater’s
Guide
15637H: Hardenability
Curves. Heat-treating
“C (1600 “F). Austenitize:
845 “C (1550 “F)
temperatures
recommended
Hardness limits for specification wrposes I distance, nm
Hardness, HRC Maximum hlinimum
.5
58 57 56 54 53 51 50 47 38 30 28 26 25 23 .
1 3 5 !O !5 10 I5 10 15 i0
iardness wrposes I distance, /I6 in.
0 1 2 3 4 5 6 8 !O :2 14 :6 :8 ‘0 ‘2
50 50 49 46 39 31 26 23 20
limits for spe cification Hardness, HRC hlav
imum 58 56 55 54 53 52 51 50
50 50 49 48 43 37 33 26
45 . 40
22
33
20
21
29 27 25
. 23 21
hlinimum
by SAE. Normalize (for forged or rolled specimens
only): 870
1
High Manganese
Carbon
Steels (1500 Series) / 249
1541,154lH Chemical
COITIpOSitiOrL 1541. AK1 and UNS: 0.36 to 0.41 C, I .3s to I .65 Mn. 0.040 P max. 0.050 S max. 1541H. UNS 15410 and SAE/AISI 1541H: 0.35 to 0.45 C. I.25 to I .75 Mn. 0. IS to 0.35 Si; IS-l I was fotmerl)
designated as IOXX grade: Composition range and limits for 1JNS G IS-I IO and AISVSAE IS-II: 0.36 to 0.45 C. 1.30 to I.65 Mn
Similar Steels (U.S. and/or Foreign). 1541. UNS Gls110: ASTM AS IO, AS 19. A53.5. AS-l6: SAE J-103. J-II?. J-II-l; tGer.j DIN I.1 Ihl:(Fr.) AFNOR-IOMS:(Jap.) JISSMn 2 H,SMn2,SCMn3: (Swed.) SSll 2120. 1541H. LINS HISJIO: SAE 51268; (Ger.) DIN 1.167; (Fr.) AFNOR 40 M 5; (Jap.) JIS Shin 2 H. SMn 2, SChln 3; (Swed.) SS 1-12 I20 Characteristics. Essentially a 1030 with a higher manganese content. This greatly increases its hardenahility. As-quenched hardness about 52 HRC or slightly greater. L+hen fully hardened. However. IS-11 H is relatively deep hardening. so that oil quenching can he used for considerably heavier sections when compared with IWO. Grade IS-11 H is available in various product forms. Forgeability is good. Machinabilit] is fair. Can be welded. using practice recommended for other high-hardenabilit) steels
Hardening. Heat to 845 jC (ISSS “F). Carbonitriding is a suitable surface hardening process. Except for very heavy sections. oil quench from austenitizing temperature. as u ith alloq steels. Water of brine quenching may cause quench cracking. Full precautions should be taken when parts made from I S-l I H are induction hardened. Overly severe quenching may also result in quench cracking Tempering matel)
Normalizing.
Recommended l
l l
Practice
Heat to 900 “C ( I650 “FL Cool in air
l
Heat Treating
Annealing.
Heat to 830 “C ( IS25 “F). Furnace cool to 650 “C ( I200 ‘IF) at a rate not to exceed 28 “C (SO “F) per h
1541: Continuous
Cooling Transformation
“C(1320”F).Ac,at790”C(1455”F)
Diagram. Composition:
of approxi-
After Normalizing. Normalize large sections by conventional practice. u hich results in a structure of fine pearlite. Temper to about 530 “C (I000 “F). hlechanical properties not equal to those achieved b> quenching and tempering. Resulting strength is far higher than annealed structure. Normalize and temper heavy forgings
l
Recommended
hardness
Tempering
l
Forging. Heat to IZ-IS “C (177S “F). Do not forge below 870 “C (I600 “F). For 1511 H, drop forge from I205 to 850 “C (2200 to I560 “F)
After Hardening. As-quenched 57 HRC can be reduced by tempering
l
l
Processing
Sequence
Forge Normalize Anneal c’if necessary) or temper (optional) Rough machine Austenitizc Quench Temper Finish machine
0.39 C. 1.56 Mn. 0.010
P, 0.024
S, 0.21 Si. Grain
size, 8. AC, at 715
250 / Heat Treater’s
Guide
3
1541 H: End-Quench Hardenability
I I.5 2 2.5 3 3.5 4 4.5 5 5.5 6 6.5
1.58 2.31 3.16 3.95 4.74 5.58 6.32 7.1 I 7.90 8.69 9.18 10.27
60 59 59 58 57 56 55 53 52 SO 48 46
53 52 50 47 4-l 41 38 35 32 29 27 26
7 7.5 8 9 IO I’ l-4
I6 18 20 22 2-t
II.06 I I .85 12.64 13.22 15.80 I8.% 22.12 25.28 28.U 31.60 34.76 37.92
44 II 39 35 33 32 31 30 30 29 28 26
25 24 23 23 22 21 20
1541: Hardenability of Oil-Quenched Bolts. Curves represent average as-quenched hardnesses of 15 bolts 19 mm (0.75 in.) from one heat. C is center of bolt; 0.5R is mid-radius; S is sur-
1541: Isothermal Transformation Diagram. Composition: 0.43 C, 1.57 Mn, 0.011 P, 0.029 S, 0.23 Si, 0.20 Ni, 0.12 Cr, 0.07 MO. Austenitized at 900 “C (1650 “F)
1541, 1541H: Hardness vs Tempering Temperature. Represents an average based on a fully quenched structure
High Manganese
1541 H: Hardenability Curves. Heat-treating (1600 “F). Austenitize:
Hardness purposes J distance, mm 1.5 3 5 7 9 II 13 IS 20 25 30
845 “C (1550 “F)
limits for specification Hardness, ARC Minimum Maximum 60 59 57 53 49 4-l 38 35 32 30
53 50 4.3 36 29 25 23 ‘2 20
Hardness limits for specification 3urposes I distance,
VI/la in. I.5 , !.S 1.5 1.5 i.5
is ‘S I
0 2 4 6 8 10 12 !I
Hardness, EIRC hlaximum hlinimum 60 59 59 58 57 56 55 53 52 50 48 46 44 41 39 3s 33 32 31 30 30 29 28 26
53 52 SO 47 4-l 41 38 35 31 29 27 26 25 2-l 23 23 22 21 20
temperatures
recommended
Carbon
Steels (1500 Series) / 251
by SAE. Normalize (for forged or rolled specimens
only): 870 “C
252 / Heat Treater’s
Guide
1541: Microstructures. (a) Nital, 330x. Forged at 1205 “C (2200 “F). Cooled in air blast. Widmanstatten platelets of ferrite at prior austenite grain boundaries and within grains. Martensite matrix. (b) Nital, 550x. Forged at 1205 “C (2200 “F), but cooled in milder air blast. Slower cooling rate resulted in upper bainite formation (dark areas). Martensite matrix. (c) Nital, 2850x. Forging and cooling same as (b). Replica electron micrograph. Etched areas are upper bainite, consisting of carbide particles in ferrite. Smooth, featureless areas are martensite. (d) 2% nital, 110x. Hot rolled steel bar. 23.82 mm (0.94 in.) in diam. Transverse section. Top surface shows 0.254 mm (0.010 in.) deep seam and partial decarburization (white areas). Ferrite core (white) outlining prior austenite grains in pearlite matrix (dark). (e) 1% nital, 100x. Forging lap of steel austenitized at 870 “C (1600 “F) for 2 h. Water quenched. Tempered at 650 “C (1200 “F) for 2 h. Iron oxide (dark); ferrite (light); tempered martensite. Core is ferrite and tempered martensite. (f) 1% nital, 100x. Elongated forging flap in steel that was austenitized. Water quenched. Tempered to hardness, 25 to 30 HRC. Iron oxide (dark). White area surrounding flap is caused by decarburization. Hemainder is tempered martensite
252 / Heat Treater’s
Guide
15B41H Chemical Composition. UNS H15411 and SAE/AISI: 0.35 IO 0.45 C. I.75 to I .75 hln. 0. I.5 to 0.35 Si (0.0005 to 0.003 B can be expected) Similar
Steels (U.S. and/or
Foreign).
LINS
HI s-11 I;
SAE
J 1268: (Ger.) DIN I .5X7
Characteristics. A boron treated IS-II H. Significant increase in hardenability caused b) boron addition. Forgeability is good. hlachinabilit) is fair. Weldability IS poor Forging.
Heat to IX5
Recommended Normalizing.
“C (2775 “FL Do not forge below 870 “C I 1600 “F)
Heat Treating
Practice
Heat to 900 “C ( I650 “F). Cool in air
Annealing. Heat to 830 “c ( IS15 “F). Furnace cool to 650 “C t I ZOO “FJ at a rate not to exceed 28 “C (SO “F) per h
Hardening.
Heat to 8-15 “C t IS_55 “F).Carbonitriding is a suitahle surface hardening process. Should he regarded as an alloy steel in quenching from austenitiring temperature. Usually quenched in oil. except for very hea\! sections. L\‘ater or brine quenching likely to result in quench cracking. Full precautions should be taken when parts are induction hardened. Overly severe quenching can also cause quench cracking
Tempering
After Hardening.
Hardness
of nppmximntely
52 HRC
can be reduced b! tempenng
Tempering After Normalizing. For large sections, normalize by cowentional practice. Results in structure of tine pearlite. Temper up to about S-10 “C (I000 “F). hlechanical properties not equal to those achieved h) quenching and tempering Resulting strength far higher than that of annealed structure. Normalize and temper heavy forgings
High Manganese
Recommended l l l l l l l l
Processing
For&e Normalize Anneal (if necessxy) Rough machine Austenitize Quench Temper Finish machine
I
1 3 .I 5 6 7 8 9 IO II 1 I2
I.33 3.16 4.74 6.3’ 7.90 9.18 II 06 12.6-i
11.22 IS.80 17.38 18.96
15841 H: Hardness average
or temper (optional)
15B41H: End-Quench Distance from auenched
Sequence
Hardenability Distance from auenched
Hardness.
60 59 59 58 5x 57 s7 56 55 55 s-l 53
53 51 s2 51 51 50 49 -18 44 37 32 28
I3 II 15
I6 I8 20 22
24 26 28 30 32
Hardness,
20 5-l ‘2.12 23.70 25.28
52 91 50 49
26 25 25 2-l
xu 31.60 31.76 37.92 41.08 44.2-l 17.40 50 Sh
16 12 39 36 3-l 33 31 31
3 22 II 21 20
based
Carbon
vs Tempering
on a fully quenched
Steels (1500 Series) / 253
Temperature. structure
Represents
an
254 / Heat Treater’s
Guide
15841 H: Hardenability
Curves. Heat-treating
“C (1600 “F). Austenitize:
845 “C (1550 “F)
Hardness purposes J distance, mm 1.5 3
5 I 9
11 13 15 20 25 30 35
40 45 50
Hardness purposes I distance, ‘/,fj in.
limits for specification Eardoess, ARC Maximum Minimum 60 60 59 58 58 51 56 55 53
50 45 39 35 32 31
limits for specification Eardness, q RC Maximum hlinimum
1
60
2 3
59 59 58 58 51 51 56 55 55 54 53 52 51 50 49
4 5 6
I 8 9
10 11 12 13 14 15 16 18 20 22 24 26 28 30 32
53 52 52 51 50 49 47 41 26 24 23 21 20
46 42 39 36 34 33 31 31
53 52 52 51 51 50 49 48 44 37 32 28 26 25 25 24 23 22 21 21 20 ...
temperatures
recommended
by SAE. Normalize (for forged or rolled specimens
only): 870
High Manganese
15B41H: Continuous Cooling Transformation Diagram. Composition: ASTM 7 to 8. AC, at 725 “C (1335 “F). AC, at 780 “C (1435 “F)
Carbon
Steels (1500 Series) / 255
0.42 C, 1.61 Mn, 0.006 P, 0.019 S. 0.29 Si, 0.004 B. Grain size.
High Manganese Carbon Steels (1500 Series) / 255
1548 Chemical
COInpOSitiOn. AISI and UNS: 0.35 to 0.56 C. 0.85 to I. I5 Mn, 0.040 P max. 0.050 S max. UNS Cl5480 and AISl/SAE 15-W Standard composition ranges and limits: 0.42 to 0.43 C. I .OS to I .-IO Mn; was formerly designated as IOXX grade
Similar Steels (U.S. and/or Foreign). A510; SAEJ403.
Wl2,
IJNS
GlS180;
ASTM
J-II-I: (Ger.) DIN I.1226
Characteristics.
High-manganese version of 1045. Slight difference in composition provides for higher hardenability. As-quenched hardness of at least 55 HRC or slightly higher. when carbon is near the high side of the allowable range. Used extensively for parts to be furnace heated or heated by induction prior to quenching. Excellent forgeability. Fair machinability
Forging.
Heat to I245 “C (2275 “R. Do not forge below 870 “C ( 1600 “F)
Recommended Heat Treating Practice Normalizing. Heat to 900 “C (1650 “F). Cool in air
Tempering After Hardening. erly austemtized
Hardness of at least 55 HRC. if propHardness can be adjusted by tempering
Tempering After Normalizing. For large sections. normalize by conventional practice. This results in a structure of fine pearlite. A tempering treatment up to approximately 540 “C (I000 “F) is then applied. Mechanical properties not equal to those achieved by quenching and tempering. Resulting strength is far higher than that of annealed structure. Normalizing and tempering often applied to heavy forgings Recommended l l
l
Annealing. Heat to 84 “C (I555 “F). Furnace cool to 650 “C ( 1200 “F) at a rate not to exceed 28 “C (SO “F) per h
l
Hardening.
l
Austenitize at 815 “C (1555 “Fj. Carbonitriding is a suitable surface hardening process. Because of high hardenability, a less severe quench may be desired for a given section thickness
and quenched.
l
l l
Processing
Sequence
Forge or machine (from bars) Normalize (if forged. Not required for parts machined from hot rolled or cold drawn bars) Anneal (if necessary. Bar stock usually received in condition for best machining) Rough machine (forgings) Austenitize (parts from bars or forgings) Quench Temper Finish machine
256 / Heat Treater’s
Guide
1548: Hardness vs Tempering Temperature. average based on a fully quenched
structure
Represents
an
256 / Heat Treater’s
Guide
15B48H Chemical
Composition.
to0.53 expected)
C. 1.00 to I.50 hln. 0.15 to 0.35 Si (0.0005 to 0.003 B can be
0.13
UNS HI5481
and SAE/AISI
ISBJSH:
Tempering
After Hardening.
As-quenched
hardness
of 55 HRC
can be reduced hy tempering
Characteristics. Composition similar to 15-18 with boron added. Characteristics, other than hardenahility. are the same. Forgeability is excellent. Machinability is fair
Tempering After Normalizing. For large sections. nomlalize hy conventional practice. This results in a structure of fine pearlite. A tempering treatment up to approximately S-IO YY (1000 “F) is then applied. hlrchanical properties not equal to those achieved by quenching and tsmperin~. Resulting strength is far higher than that of annealed structure. Normnhrmg and tempering often applied to heavy forgings
Forging.
Recommended
Similar
Steels (U.S. and/or
Foreign).
1JNS H Is181 : WE
J 1268
Heat to ILIS “C (2275 OF-,. Do not forge below 870 “C ( 1600 ‘F)
Recommended Normalizing.
Heat Treating
l
Practice
l
Heat to 900 C. i I650 “F). Cool in air l
Annealing.
Heat to 815 “C ( IS55 “FL Furnace cool to 650 “C t I200 “F) at a rate not IO exceed 28 “C (SO “F) per h
l l
Hardening.
Austenitize at MS “C I ISSS “F). Carbonitriding surface hardening process. Quench in oil except for thicker induction hardened, use extreme care when \\ater quenching
is a suitable sections. If
from
I 1 3 4 5 6 7 8 9 IO II I2
from quenched
Distance Eardness, HRC mar min
I.98
63
56
1.7-l 3.16 6.32 1.90 948 II.06 I2.64 1122 IS.80 17.38 18.96
62 61 60 59 58 57 56 s.5 53 51
56 55 s-l 43 52 -12 3-l 31 30 29 28
Aardness,
surface &in.
I3 I-l IS I6 I8 30 22 2-l 26 28 30 31
ARC mm
20.51 22. I2 23.70 25.23 28.U 3 I ho 34.76 37.92 41.08 u.21 47 -IO 50.56
l l
15848H: End-Quench Hardenability Distance
l
max
min
48 -Is II 3x 31 32 31 30 19 29 28 ‘8
27 37 26 26 IS 2-l 73 22 21 20
Processing
Sequence
Forge or machine t from bars) Normalize tif forged. Not required for parts machined from hot rolled or cold dran n bars) Anneal tif necessary. Bar stock is usually received in condition for best machining) Rough machine (forgings) .Austenitize Quench Temper Finish machine
High Manganese
15848H: Hardenability
Curves. Heat-treating
“C (1600 “F). Austenitize:
Hardness purposes J distance, mm
1.5 3 5 7 9 11 13 15 20 25 30 35 40 45 50
Hardness purposes J distance, ‘/,,jin.
1 2 3 1 5 5 7 3 2 IO I1 12 13 14 I5 I6 18 !O !2 !4 !6 !8 10 12
845 “C (1550 “F)
limits for specification Eardness, Maximum
ERC hlinimum
63 63 62 61 60 59 57 56 49 39 33 31 30 29 28
56 55 55 54 53 45 33 30 27 25 24 23 22 . ...
limits for specification Eardoess, Maximum
63 62 62 61 60 59 58 57 56 55 53 51 48 45 41 38 34 32 31 30 29 29 28 28
HRC hlinimum
56 56 55 54 53 52 42 34 31 30 29 28 27 27 26 26 25 24 23 22 21 20
temperatures
recommended
by SAE. Normalize
Carbon
Steels (1500 Series) / 257
(for forged or rolled specimens
only): 870
258 / Heat Treater’s
Guide
15848H: Hardness vs Tempering Temperature. Represents an average based on a fully quenched
structure
258 / Heat Treater’s
Chemical
Guide
Composition.
AISI and UNS: 0.45 to 0.56 C. 0.85 to
I .I5 Mn. 0.040 P max. 0.050 S max
Similar
Steels (U.S. and/or
Foreign).
UNS Gl5510;
ASTM
ASIO; SAEJ403. J413, J414
Characteristics. Carbon content as high as 0.56. Borderline grade hetween medium carbon and high carbon. Available in various product forms. Used extensively for producing small to medium size forgings. Often selected for parts to be induction hardened. Excellent forgeability. Fairly good machinability. Weldability is poor. Similar to 1050. Higher manganese content increases hardenability Forging.
Heat to 1230 “C (2250 “F). Do not forge below 845 “C ( IS55
Hardening. Heat to 830 “C ( I525 “F). Carbonitriding and induction hardening are suitable surface hardening processes. Quench in water or hrine. For full hardening, oil quench rounds less than 6.4 mm (‘/J in.) thick. High hardenability must be considered in quenching. Normalize and temper as for I54 I. if desired Tempering.
Recommended l l
“F)
l
Recommended Normalizing. Annealing.
Heat Treating
Practice
l l
Heat to 900 “C ( 1650 “Ft. Cool in air
Heat to 830 “C (I 525 “F). Furnace cool to 650 “C t I200 “F) at a rate not to exceed 28 “C (SO “F) per h
As-quenched
hardness of 58 to 60 HRC can be reduced by
tempering
l l l
Processing
Sequence
Foge Normalize Anneal Rough machine Austenitize Quench Temper Finish machine
1551: Hardness vs Tempering average
based
on a fully quenched
Temperature. structure
Represents
an
High Manganese
Chemical
Composition. AISI and UNS: 0.47 to 0.55 C. 1.20 to I .50 Mn. 0.040 P max. 0.050 S max. UNS Cl5520 and AISI/SAE 1552:
Composition limits formerly designated
Similar
and ranges: 0.46 to 0.55 C. 1.20 to I.55 Mn: uas as I OXX grade
Steels (U.S. and/or Foreign).
A510: SAEJ403.
J412.5414;
UNS
G 15520;
ASTM
(Ger.) DIN I.1226
Characteristics. Carbon content as high as 0.55. Borderline grade between medium carbon and high carbon. Available in various product forms. Used extensively for producing small to medium size forgings. Often selected for parts to be induction hardened. Excellent forgeability. Fairly good machinability. Weldability is poor. Similar to 1050. Higher manganese content increases hardenability Heat to I230 “C (2250 “F). Do not forge below 815 “C ( I555
“F3
Heat to 830 “C ( IS25 “FL Furnace cool to 650 “C ( I200 “F) at a rate not to exceed 28 “C (SO “F) per h
Hardening. Heat to 830 “C ( 1525 “F). Carbonitriding and induction hardening are suitable surface hardening processes. Because of higher hardenability. oil quench heavier sections for full hardness. When induction hardening, use the least severe quench that \rill produce full hardness. This minimizes the possibility of quench cracking Tempering.
Recommended l
l
l
Heat Treating
Practice
l l
Normalizing.
Heat to 900 “C ( 1650 “F). Cool in air
As-quenched
hardness of 58 to 60 HRC can be reduced by
tempering
l
Recommended
Steels (1500 Series) / 259
Annealing.
l
Forging.
Carbon
l
Processing
Sequence
Forge Normalize Anneal Rough machine Austenitize Quench Temper Finish machine
1552: Hardness average
based
vs Tempering on a fully quenched
Temperature. structure
Represents
an
High Manganese
Carbon
Steels (1500 Series) / 259
1561 Chemical
COI?IpOSitiOn. AK1 and UNS: I .OS Mn. 0.040 P max. 0.050 S ma-x
Similar
Steels (U.S. and/or Foreign).
0.55 to 0.65 C. 0.75 to LINS
G 15610;
ASTM
Tempering.
A510: SAE J403. J112
Characteristics. Versatile high-carbon grade. Available in a variety of product forms. including various thicknesses of flat stock used for fahricating parts to be spring tempered. Good forgeahility. Not recommended for welding. As-quenched hardness of near 65 HRC can be expected. When properly quenched. consists of a carbon-rich martensite structure with essentially no free carbide. Similar to 1060. with slightly higher hardenability and manganese content Forging.
Hardening. Heat to 815 ‘C. t IS00 “F). Carbonitriding surface hardening process. Hardenability must be considered Oil quench sections thicker than for 1060
Heat to 1205 “C (2200 “F). Do not forge below 815 “C ( IS00
“F)
Austempering.
Thin sections ttypically springs) usually austempered. Results in hainitic structure. Hardness of approximately 46 to 52 HRC. Austenitire at 8 IS “C t I500 “F). Quench in molten salt bath at 3 IS “C (600 “F). Hold at temperature for I h. Air cool. No tempering required
Recommended l
l
Normalizing. Annealing.
Heat Treating
Practice
Heat to 885 “C ( I625 “F). Cool in air
Heat to 830 ‘C t I535 “FL Furnace cool to 650 “C t I200 “F) at a rate not to exceed 28 “C (50 “F) per h
hardness near 65 HRC can be reduced by tem-
pering
l
Recommended
Maximum
is a suitable in quenching.
l l l l l
Forge Normalize Anneal Rough machine Austenitize Quench Temper Finish machine
Processing
Sequence
260 / Heat Treater’s
Guide
1561: Hardness vs Tempering Temperature. average based on a fully quenched
structure
Represents
an
260 / Heat Treater’s
Guide
15B62H Chemical COfIIpOSitiOfI. CJNS HlS621 and SAE/AISI lSB62H: 0.5-f to 0.67 C. I .OO IO I SO hln. O.-IO to 0.60 Si (0.0005 to 0.003 B can be expected) Similar
Steels (U.S. and/or
Foreign).
IINS H 1562 I : SAE J I 368
Austempering. Thin sections (typically springs) commonly austempsred. resulting in bainitic structure and hardness of approximately 45 to 52 HRC. Austenitizr at 8 IS ‘C t I SO0 “Ft. Quench in molten salt bath at 3 IS “C (600 “Ft. Hold at this temperature for I h. Air cool. No tempering required
Characteristics.Similx
to 1060. Good forgeability. Poor uvldability. Maximum as-quenched hardness of 65 HRC. Higher manpanese content. boron addition, and higher silicon content all contribute to its relatively high hardenability. Extensively used in the spring temper hardness range. generally 35 IO 52 HRC. for springs having relatively thick sections
Forging.
Heat to 1205 “C t7200 “FL Do not forge below 8 IS “C I I SO0 “F)
Tempering.
As-quenched hardness from 63 IO 65 HRC. This maximum hardness can be reduced by tempering
Recommended l
Recommended Normalizing.
Heat Treating
Practice
l l
Heat to 885 “C (1625 “FL Cool in au
l
Annealing.
Heat IO 830 “C t IS25 “FL Furnace cool to 650 “C t I200 “FJ at a rate not to exceed 28 “C (SO “FJ per h
Hardening. Austenitizc at 8 IS ‘C t 1SO0 ‘:‘F). Carbonitriding surface hardening process. Quench in oil 15662H: End-Quench Hardenability Distance from quenched surface
&in.
mm
Hardness. ERC max min
I -3 3 -l 5 6 7 8 9 I0 II I?
1.5x 3.16 47-i 6.32 7 90 9 18 Il.06 116-I l-t.22 IS.80 17.38 IX.96
60 60 60 60 59 58 57 52 43 39 37 s5
I
& 65 6-t 6-l 6-1 63 63 63
Distance from quenched surface I,/16in. mm 13 I-l IS I6 I8 20 22 2-I 26 28 SO 32
30.54 22.12 23.70 3.28 3 4-l 3 1.60 34.76 37 92 11.08 44.2-I 47.40 SO.56
is a suitable
l l l l
Forge Nomlalizs .Anneal Rough machine Austenitize Quench Temper Finish machine
Processing
Sequence
High Manganese
15B62H: Hardenabilitv
Curves. Heat-treating
“C (1600 “F). Austenitiie:
Hardness purposes J distance, mm 1.5 3 5 7 9
11 13
15 20 25 30 35 40 45 50
temperatures
recommended
by SAE. Normalize
Carbon
Steels (1500 Series) /
(for forged or rolled specimens
only): 87C
845 “C (1550 “F)
limits for spec ification Hardness, Maximum
ARC Minimum
60 60 60
.. 65 65 65 65 64 64 63 60 56 48 42 37 34
59 58 56 50 42 34 32 31 30 29 27 26
I
Hardness purposes J distance, ‘&j in.
limits for specification Hardness, Maximum
1 2 3 4 5 6 7 8 9
10 11 12 13 14 15 16 18 20 22 24 26 28 30 32
. 65 65 64 64 64 63 63 63 62 62 61 60 58 54 48 43 40 31 35 34
H RC Minimum 60 60 60 60 59 58 57 52 43 39 31 35 35 34 33 33 32 31 30 30 29 28 21 26
262 // Heat Heat Treater’s Treater’s 262
Guide Guide
15662H: Hardness vs Tempering Temperature. Represents an average based on a fully quenched
structure
262 / Heat Treater’s
Guide
1566 Chemical
Composition.
AISI and UN% 0.60 to 0.71 C. 0.85 to
I. I5 Mn, 0.040 P max. 0.050 S max
Similar
Steels (U.S. and/or
Foreign).
UNS
G15660;
ASThl
AS IO; SAE 5403. J4 12; (Ger.) DIN I. I260
Characteristics. High-manganese version of 1070. Widely used in the hardened and tempered (notably spring tempered) condition. ?iood forgeability and shallow hardening. Extensively used for making hand tools such as hammers and woodcutting saws. Not recommended for welding Forging.
Heat to I 190 “C (2 175 “F). Do not forge below 8 IS “C ( I500 “F)
Recommended Normalizing.
Heat Treating
Practice
Heat to 885 “C ( I625 “F). Cool in air
Austempering. Thin sections (typically springs) are commonly austempered. resulting in bainitic structure and a hardness range of approximitely 46 to 53~HRC. Austenitize 91 815 “C (I500 “F’). Guench in molten salt bath at 3 IS “C (600 “F). Hold a1 temperature for I h. Air cool. No tempering required Tempering.
Recommended l l l
Annealing.
Heat to 830 “C ( IS25 “F). Furnace cool to 650 “C ( I200 “F) at a rate not to exceed 28 “C (50 “F) per h
Hardening. Heat to 815 “C (IS00 “F). Carbonitriding is a suitable surface hardening process. Lessen severity of quench to avoid cracking compared with quenching of 1070
Maximum
hardness near 65 HRC can be reduced by tem-
pering
l l l l l
Processing
Sequence
Forge Normalize Anneal Rough machine Austenitize Quench Temper Finish machine
1566: Isothermal Transformation Diagram. Contains 0.64 C and 1 .13 Mn. Grain size 7. Austenitized at 910 “C (1670 “F). Martensite temperatures estimated
High Manganese
Carbon
Steels (1500 Series) / 263
1566: End-Quench Hardenability. Contains 0.68 C and 1 .OOMn. Grain size, 6 to 7. Austenitized at 845 “C (1555 “F)
1566: Hardness vs Tempering Temperature. average based on a fully quenched structure
Represents
an
(1300
Alloy
Steels
through
9700
The alloy steels discussed in this section. as \vell as their subsequent heat treatment. are those listed in the latest issue of the 41SI Steel Products hlanual on alloy steel bars. They include both ths standard alloy steels and the standard H and RH steels. H hich have modified hardenability limits. They also have sliphtly different carbon ranges. generally broader than the standard alloy steels. These steels are similar to standard grades in other respects. including thek general characteristics and recommended heat treating practice. There are fourteen separate families of alloy steels that rve considered standard. In numericnl sequence. these steels begin with the I300 manpanese steels and conclude with 9160 manganese-silicon steels. Boron-modified allo! steels generalI) contain 0.0005 to O.O03r(~ boron. There are five families of boron-modified allo) steels bepmnlng with
Series)
SOB00 chromium steels and concluding u ith the WBOO nickel-chromiummolybdenum steels. Because of the very small amounts of boron used, boron is not considered as an alloy. These steels. which are denoted by the USP of the letter “B” bet\\een the second and third digits of their designations. are instead commonI> referred to as boron-treated steels. Boron is used for the purpose of increasmg hardenability. When the endquench data for an! specific boron steel are compared with its counterpart not containing boron. the effect of boron hecomes evident. The use of boron steels has provided an economic advantage because It offers high bardenability in IOU-allo! steels. significantly louer in cost than the higher allo) grades that would be necessary to provide the hardenability required u ithout the boron.
1330,133OH Chemical Composition.
1330. AISI and ZJNS: 0.18 to 0.23 C. I .60 to I .90 hln. 0.035 P milx. 0.040 S max. 0. IS IO 0.30 Si. UNS H13300 and SAE/AlSI 1330H: 0.27 IO 0.33 C. I .-iS to 2.05 hln. 0. IS to 0.35 Si.
Similar Steels (U.S. and/or Foreign).
l!NS G 13300: 1330. ASTM A304. A322. 44331. 4519: hllL SPEC hlR--S-16974; SAE J4o-I. J-ii?. 5770; (Ger.) DIN I.1 165: tJap.j JIS Shln I H. SChln 2. 1330H. LINS Hl3300: ASThI A3O-k SAE JlZ68: tGer.) DIN I.1 165: tJap.) JIS Shin I H, SChln 2
Characteristics. A medium-carbon iteel of the manganese allo! steel series. While the manganese content of I330H can overlap \\ nh the manganese content of the high-manganese carbon steels. the nominal manganese content IS considerably higher for 1330H. givmg the steel higher hardenability. Thus. with a carbon content in thr middle of the range. as-quenched hardness can be expected to approach SO HCR. This steel is usually oil quenched. although large sections may have IO be irater quenched to develop maximum hardness. H’ater quenching of l330H is hazardous because high-manganese steels are susceptible to quench cracbing. This applies especialI) to induction or name hardenmg. M’hen these processes are used. the quenching phase of the process must be extremeI> \rell controlled. l33OH can be welded only when close,l>, controlled preheating and postheattng practices are follo\ good. but machinabilit) is only fair
Recommended Heat Treating Practice Normalizing. Heat to 900 jC t l6SO “F). Cool in air Annealing. For a predominately pearlitic structure. heat
to 855 “C (I 570 “F). and cool IO 620 ‘C t I IS0 “F) at a rate not to esceed I I “C (30 “F) per h: or cool fairly rapidlq IO 620 “C ( I I SO “F) and hold for 4 t/z h after which cooling rate is not critical. To obtain a structure predominately composed of femte and spheroidired carbide. heat IO 750 “C (I 380 OF). cool fairly rapidly to 730 “C t I350 “Fj. Then cool to 6-lO “C ( I I85 “F) at a rate not to exceed 6 C t IO “F) per h and hold for IO h. after which cooling rate is no longer critical
Hardening. Austenitize at 860 “C t IS80 “F). and quench in oil. Use water or brine for hea\> secttons. Carbomtriding. austempering. and niartsnipcring are suitable processes. Tempering.
Recommended Processing see 1335 and 1335H) l l l l l l
Forging.
Heal to I230 ‘C i224S “F). Do not forge after temperature belo\v approsimately 870 “C ( I600 “F)
drops
Temper to desired hardness
l l
Rough machine Slress relic\ e Finish machine Preheat Auslrnilize Quench Temper Final grind to size
Sequence
(if forged,
266 / Heat Treater’s Guide
1330H: End-Quench Hardenablllty Distance from quenched surface 916 in. mm
Ehrdoess, ERC max min
Distance from quenched surtkce ‘/la in. mm
Eardlless, ERC max min
I 2 3
1.58 3.16 4.74
56 56 55
49 47 44
13 I4 I5
20.54 22.12 23.10
38 31 36
4 5 6 7 8 9 IO II 12
6.32 1.90 9.48 Il.06 12.64 14.22 15.80 17.38 18.96
53 52 50 48 45 43 42 40 39
40 35 31 28 26 25 23 22 21
I6 18 20 22 24 26 28 30 32
25.28 38.44 31.60 3-1.76 37.92 41.08 44.24 47.40 50.56
35 3-l 33 32 31 31 31 30 30
Source: Metals Handbook.
20 ___
9th ed.. Vol I. American Socier) for Metals. 1978
1330: Effect of Hot Working and Location of Test Bars on End-Quench Hardenability. diam. (c) 203 mm (8 in.) diam. (d) 152 mm (6 in.) diam.
(a) 305 mm (12 in.) diam. (b) 254 mm (10 in.)
Alloy Steels (1300 through
1330H: Hardenability
Curves. Heat-treating temperatures
(1650 OF). Austenitize:
870 “C (1600 “F)
Hardness Purposes J distance, mm 1.5 3 5 7 9 II 13 15 20 25 30 35 40 45 SO
Hardness Purposes J distance, ‘46in. I 2 3 1 5 5 1
3 2 IO II 12 13 I4 IS 16 I8 !O !2
!4 !6 !8 IO i2
Limits for Specification Eardness, ERC Minimum Maximum 56 56 55 53 51 48 45 43 39 35 33 32 31 31 30
49 41 44 38 32 28 25 24 20
.
Limits for Specification Eardoess, EIRC Minimum Maximum 56 56 55 53 52 50 48 45 43 42 40 39 38 37 36 35 34 33 32 31 31 31 30 30
49 47 4-l 40 35 31 28 26 2s 23 22 21 20
recommended
9700 Series) / 267
by SAE. Normalize (for forged or rolled specimens
only): 900 “C
266 / Heat Treater’s
Guide
1330: Continuous Cooling Transformation (1580 “F). Previous treatment, rolled
Diagram.
Composition:
0.30 C. 1.80 Mn, 0.020 P, 0.020 S. 0.15 Si. Austenitized
at 860 “C
268 / Heat Treater’s
Guide
1335,1335H Chemical Composition. 1335. MS1 and UN.9 0.33 LO 0.38 c. I .60 to I .YO hln. 0.035 P max. 0.040 S max. 0.15 LD0.30 Si. UNS H13350 and SAE/AISI 13358: 0.32 IO 0.38 C. I .-IS m 2.05 hln. 0. IS to 0.35 SI
SAE J-107; (Ckr.1 DIN I. 1167; tFr.) AFNOR Shln 2. SChln 3: ~S\rsd.) S.514 2120:
Characteristics.
Similar
Steels (U.S. and/or
Foreign).
1335. ClNS GI 3350: ASTh,l ,432. A3.31. A5lY. A547: hllL SPEC hlK-S-16974: S.L\E J-10-l. J-II?. 5770: (Ger.) DIN I.1 167; tFr.) .L\FNOR 40 hl S: ~Jap.) JIS Shln ? H. Shln 2, SCh4n 3; tSutd.) S.SIJ 2120. 13358. UNS Hl.1350; XSThl.-\304:
-IO hl 5: (Jnp.) JIS Shln 2 H.
The general chzuxkrisric~ me warI> the sane ;LS those pilen for I73OH. Expected ns-quenched h:udnrs for l33SH is sliphtlb hiphsr than that for 133OH. appro\inwl4> 52 HRC. Hwdenubilitl pnltttm, ;ue i1lw knilur. Thib stesl is uzuull> oil quenched. although larg? wctionb nxq hn\s ICYbs \\~er qwnchsd 10 develop marimuni hxdnsss.
Alloy
Steels (1300 through
9700 Series) / 269
LVater quenching high-manganese steels is hazardous because of their susceptibility to quench cracking. This applies especially to induction or flame hardening. When these processes are used. the quenching phase of the process must be extremely well controlled. l33SH can be welded. but only when closely controlled preheating and postheating practices are followed. Forgeability is very good, hut machinability is only fair
exceed 6 “C I IO “F) per h and hold for IO h. after which cooling longer critical
Forging.
Tempering.
drops helou
Heat to 1230 “C (3345 “F). Do not forge atier temperature approxtmately 870 “C i I600 “F)
Recommended Normalizing.
Heat Treating
Heat to 900 “C (I650
l
“Ft. Cool in air
l
Annealing.
For a predominately pearlittc structure, heat to 855 “C ( IS70 “F). and cool to 610 “C ( I I SO OF) at a rate not to exceed I I “C i30 “F) per h: or cool fairly rapidly to 620 “C (I I SO “F). and hold for-t vz h. after u hich cooling rate is not critical. To obtain a structure predommately composed of ferrite and spheroidized carbide. heat to 750 “C ( I385 “F). cool fairly rapidly to 730 ‘C ( I350 OF). Then cool to 640 “C ( I I85 “F) at a rate not to
1335: Isothermal Transformation
Diagram. Composition:
1335: End-Quench Hardenability Hardness, ARC max min
-I ; 4
I S8
98
1.74 3.16 6 32
s7 56 5s
51 -19 47 4-l
1, 7 8 9 IO II I2
9.48 7 90 I Ia6 I’64 13.12 15.80 17.38 18.96
92 5-I so 18 46 4-l 12 41
38 34 31 29 ‘7 26 25 21
I
Distance from quenched surface ‘/16 in. mm
I3 II IS I6 I8 ‘cl 22 2-l 26 2x SO 32
20. s-l 22 II ‘3.70 25.28 28.44 3 I .hO 31.76 37 92 4l.08 4-l 2-l 47.30 SO.56
Temper to desired hardness
Eardness, HRC max min
10 39 38 37 3s 34 33 32 31 31 30 30
l l l l l l
‘3 2’ ‘2 21 20
.._
Processing
Sequence
Forge Nomralize Anneal Rough machine Austenittze Quench Temper Finish machine
0.35 C. 1.85 Mn. Austenitized
No. 2
Distance from quenched surface ‘116 in. mm
Hardening. Austenitize at 855 ‘C (IS70 “F). and quench in oil. Use water or hrine for heal y sections. Carhonitriding and mattempering are suitable surface hardening processes
Recommended
Practice
rate is no
at 845 “C (1555 “F). Grain size: 70% No. 7,30%
270 / Heat Treater’s Guide
1335H: Hardenability (1600 “F). Austenitize:
Curves. Heat-treating 845 “C (1550 “F)
Hardness Limits for Specification Purposes I disiance, nm 1.5 3 5 7 9 11 13 15 !O !5 IO 15 lo 15 i0
Eklrdness, ERC MaximlUU 58 58 51 55 53 50 47 45 41 37 35 33 32 31 30
MillilIlUUl 51 49 46 42 36 31 28 21 23 21 . .
Hardness Limits for Specification Purposes I distance, h6 in. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 18 20 22 24 26 28 30 32
Eardness, Maximum 58 57 56 55 54 52 50 48 46 44 42 41 40 39 38 37 35 34 33 32 31 31 30 30
ERC Millhull 51 49 41 44 38 34 31 29 27 26 25 24 23 22 22 21 20 ... ... ... . .. ..
temperatures
recommended
by SAE. Normalize (for forged or rolled specimens
only): 870 “C
Alloy Steels (1300 through
1335, 1335H: Hardness vs Tempering Temperature. Represents an average based on a fully quenched structure
9700 Series) / 271
1335: IlT Curve. Composition: Fe, 0.35 C, 1.85 Mn. Grain size: 70% No. 7,30% No. 2. Austenitized at 843 “C (1550 “F)
Alloy Steels (1300 through 9700 Series) / 271
1340,134OH Chemical Composition. 1340. AI.9 and UNS: 0.38 to 0.43 C. I .60 to 1.90 Mn, 0.035 P max. 0.040 S max, 0. I5 to 0.30 Si. UNS 813400 and SAE/AISI 134OH: 0.37 to 0.44 C, I.45 to 2.05 Mn, 0. I5 to 0.35 Si
Hardening. Austenitize at 830 “C (IS25 “F). and quench in oil. Use water or brine for heavy sections. Electron beam, carbonitriding. and austempeting are suitable processes
Similar Steels (U.S. and/or Foreign). 1340.
Tempering.
ASTM A322, A331. A519, A547: J412.5770. 13408. UNS Hl3400: I SO69
UNS G13400; MfL SPEC MLS-16974; SAE J404. ASTM A304; SAE J407; (Ger.) DIN
Recommended l
Characteristics.
Comparable to those outlined for I330H and I335H. As carbon content is increased, a higher as-quenched hardness can be expected (about 54 HRC for I340H. depending on precise carbon content). The hardenability pattern is also quite similar to those shown for grades l330H and 1335H. As is true for all of the I300 grades, hardenahility band is relatively wide, caused primarily by the broad range in manganese content
Temper immediately
l l l l l l l
after quenching
Processing
to desired hardness
Sequence
Forge Normalize Anneal Rough machine Austenitize Quench Temper Finish machine
Forging.
Heat to 1230 “C (2245 “F). Do not forge after temperature drops below 870 “C ( 1600 “F)
Recommended Normalizing. Annealing.
Heat Treating
Practice
1340: Specimens
As-Quenched quenched
Hardness
in oil from 830 “C (1525 “F)
Heat to 870 “C (1600 “F). Cool in air
For a predominately pearlitic structure, heat to 830 “C ( I525 “F). and cool from 730 “C (1350 “F) to 610 “C (I 130 “F) at a rate not to exceed I I “C (20 “F) per h; or cool rapidly from 730 “C (I350 “F) to 620 “C (I IS0 “F). and hold for 4.5 h. For a predominately ferritic and spheroid&d structure, heat to 750 “C (1380 “F), and cool from 730 “C ( 1350 “F) to 610 “C ( I I30 “F) at a rate not to exceed 6 “C ( IO “F) per h; or cool fairly rapidly from 750 “C (1380 “F) to 640 “C ( I I85 “F). and hold for 8h
In.
Size rouad mm
Surface
Eardness, ERC ‘/z radius
Center
‘/2
13 15 51 IO:!
58 57 39 32
51 56 34 30
57 50 32 26
I 7 4
Source: Bethlehem Steel
272 / Heat Treater’s
Guide
1340: Isothermal Transformation
Diagram. Composition:
0.43 C. 1.58 Mn. Austenitized
at 885 “C (1625 “F). Grain size: 8 to 9
1340H: End-Quench Hardenability Distance from quenched surface 1/16in. mm
Distance From Hardness, HRC max min
quenched
surface 916 in. mm
Hardness, ARC max min
I
1.58
2
3.16
60 60
53 52
13 II
20.5-l 22.12
46 44
26 3
3 -I 5 6 7 9
1.7-l 6.32 7.90 9.1x I I.06 12.64 11.23
59 58 57 56 55 5-l 51
51 49 46 10 35 33 31
I5 I6 18 ‘0 22 24 26
23 70 15.28 ‘8.U 3 I .60 34.76 37 92 41 08
-II -II 39 38 37 36 35
29 2-l 23 23 22 22 21
IO II I?
I S.80 17.38 18.96
51 50 -I8
29 18 27
33 30 32
Al.24 47.40 50.56
35 34 3-l
21 20 20
8
hwx
Mrrc~ls Mudbook. %h ed.. Vol I, imericm
Socirr)
ior hlrmls.
1978
1340: IlT Diagram. Composition: size: 8-9. Austenitlzed
Fe, 0.43 C, 1.58 Mn. Grain at 885 “C (1625 “F)
Alloy S teels (1300 through
1340H: Hardenability Curves. Heat-treating (1800 “F). Austenitize:
iardness ‘urposes distance, trn 1.5 3
5 7 9
1 3
5 0 5
0 5
0 5
0
845 “C (1555 “F)
Limits for Specification Hardness, HRC Maximum Minimum 60 60 59 58 57 56 54 52 41 41 39 37 36 35 34
53 52 50 48 42 36 32 30 26 24 23 22 21 20 20
hardness Limits for Specification ‘urposes distance,
1 2 3 4 5 6
7 8 9
0 1 2 3 4 5 6
8 0 2 4 6 8
0 2
Hardness, HRC Maximum Minimum 60 60 59 58 51 56 55 54 52 51 50 48 46
44 42 41 39 38 37 36 36 35 34 34
53 52 51 49 46 40 35 33 31 29 28 27 26 25 25 24 23 23 22 22 21 21 20 20
temperatures
recommended
9700 Series) / 273
by SAE. Normalize (for forged or rolled specimens
only): 870 “C
274 / Heat Treater’s Guide
1340: Hardness vs Tempering Temperature. Normalized at 870 “C (1800 “F). Quenched from 845 “C (1555 “F) in oil and tempered at 58 “C (100 “F) intervals in 13.718 mm (0.540 in.) rounds. Tested in 12.827 mm (0.505 in.) rounds. (Source: Republic Steel)
274 / Heat Treater’s Guide
1345,1345H Chemical Composition. 1345. AISI and UNS: 0.43 to 0.48 C, 1.60 to 1.90 Mn, 0.035 P max. 0.040 S max. 0. I5 to 0.30 Si. UNS H13J50 and SAE/AlSI 13458: 0.42 to 0.49 C. I .45 to 2.05 Mn, 0. I5 to 0.35 Si Similar Steels (U.S. and/or
UNS G 13450; Foreign). 1345. ASTM A322, A331. A519; SAE J404. J412, 5770; (Ger.) DIN 1.0912; (U.K.) B.S. 2 S 516. 2 S 517. 13458. UNS Hl3450; ASTM A304; SAE J407; (Ger.) DIN 1.0912: (U.K.) B.S. 2 S 516.2 S 517
Characteristics. The general characteristics of 1345H closely parallel those given for other medium-carbon 1300 series steels (see details for 133OH). There are exceptions. As-quenched hardness is higher. Fully hardened l345H should provide a minimum hardness of approximately 56 HRC, slightly higher if the carbon content is at the high end of the allowable range. Weldability is further decreased. Susceptibility to quench cracking is intensified as the carbon content is increased. The hardenability pattern for 1345H is very similar to that of 1340H. but adjusted upward because of the higher carbon content of I345H Forging.
Heat to 1230 “C (2245 “F). Do not forge after temperature drops below 870 “C ( I600 “F)
Recommended Normalizing.
Heat Treating
Practice
Heat to 870 “C (1600 “F). Cool in air
Annealing.
For a predominately pearlitic structure, heat to 830 “C (I525 “F). and cool from 730 “C ( I350 “F) to 6 IO “C ( I I30 “F) at a rate not to exceed I I “C (20 “F) per h: or cool rapidly from 730 “C (I 350 “F) to 620 “C (I I50 “F). and hold for 1.5 h. For a predominately ferritic and spheroidized structure, heat to 750 “C (1380 “F), and cool from 730 “C (1350”F)to610”C(1130”F)ataratenottoexceed6”C(10”F)perh:or cool fairly rapidly from 750 “C ( I380 “F) to 640 “C ( I I85 “F). and hold for 8h
Hardening. Austenitize at 830 “C (I525 “F). and quench in oil. Use water or brine for heavy sections. Flame hardening and carbonitriding are suitable processes Tempering.
Temper immediately
Recommended l
Forge NormaJize
l
Anned
l
Rough machine Austenitize Quench Temper Finish machine
l
l l l l
after quenching
Processing
to desired hardness
Sequence
Alloy Steels (1300 through 9700 Series) / 275
1345: Continuous Cooling Transformation Diagram. Composition: 0.46 C, 1.60 Mn, 0.020 P, 0.015 S, 0.25 Si. Austenitized (1560°F)
1345H:End-Quench Hardenability Distance from quenched surface
/16h. I 2 3 4 5 6 7 8 9 IO II I2
mm I .58 3.16 4.74 6.32 7.90 9.48 II.06 12.64 14.22 IS.80 17.38 I8.%
Eardness. ElRC max mlu 63 63 62 61 61 60 60 59 58 57 56 55
56 56 55 54 51 4-t 38 35 33 32 31 30
Distance from quenched surface
‘&jh.
mm
13 14 1s 16 18 20 22 24 26 28 30 32
20.54 22.12 23.70 25.28 28.4-l 31.60 34.76 37.92 41.08 44.24 47.40 50.56
Eardness, ERC min max 54 53 52 51 49 47 45 4-l 47 46 45 45
29 29 28 28 ‘7 27 26 26 25 25 24 24
at 850 “C
1
276 / Heat Treater’s
1345H: Hardenability (1600 “F). Austenitize:
Guide
Curves. Heat-treating 845 “C (1555 “F)
iardness Limits for Specification Durposes I distance,
urn 1.5
) 1 3 5 !O !5 LO 15 Kl I5 i0
iardness ‘urposes distance,
‘16io.
0
1 2 3 4 5 6 8 0 2 4 6 8 0 2
Hardness, HRC Maximum Minimum 63 63 63 62 61 60 59 58 55 51 48 47 46 45 45
56 56 54 52 46 38 35 31 29 27 26 25 24 24 24
Limits for Specification Hardness. HRC Maximum hlinimum 63 63 62 61 61 60 60 59 58 57 56 55 54 53 52 51 49 48 41 46 45 45 45 45
56 56 55 54 51 44 38 35 33 32 31 30 29 29 28 28 21 21 26 26 25 25 24 24
temperatures
recommended
by SAE. Normalize (for forged or rolled specimens
only): 870 “C
1
Alloy Steels (1300 through 9700 Series) / 277
1345, 1345l-l: Hardness vs Tempering Temperature. Represents an average based on a fully quenched structure
Alloy Steels (1300 through
9700 Series) / 277
3310RH Chemical
COIIIpOSitiOn.
133ORH. AISI and UNS: 0.08 to 0.13 C,
Characteristics.
Applications include carburized bearing and gears
0.40 to 0.60 Mn, 0.15 to 0.35 Si, 3.25 to 3.75 Ni, 1.40 to 1.75 Cr
Recommended Similar
Steels (U.S. and/or
Foreign).
SAE 3310RH. Has been added to SAE 51868 and ASTM A914. There is no existing standard H-grade
3310RH: Hardenability Curves. Heat-treating “C (1700 “F). Austenitize: 845 “C (1555 “F)
temperatures
Heat Treating
Practice
Hardening. Suitable processes include gas carburizing, liquid nitriding, gas nitriding, carbonitriding, and flame hardening
recommended
by SAE. Normalize
(for forged or rolled specimens
only): 925
(continued)
278 / Heat Treater’s
Guide
3310RH: Hardenability Curves (continued)Heat-treating only): 925 “C (1700 “F). Austenitize: 845 “C (1555 “F) iardness Qrposes I distance, om 1.5 3 5 I
9 II I3 :5 !O !S LO 15 lo 15
i0
Limits for Specification Hardness, HRC Maximum Minimum 42 42 42 41 41 40 40 39 38 37 36 35 35 34 34
37 37 37 36 3.5 34 33 32 30 29 28 27 27 26 26
temperatures recommended by SAE. Normalize (for forged or rolled specimens
278 / Heat Treater’s Guide
4023 Chemical 0.9OMn.O.15
COIIIpOSitiOn. to0.30Si.0.035
AISI and UNS: 0.20 to 0.25 C. 0.70 Pmax.0.040S max.0.20 too.30 MO
Similar Steels (U.S. and/or Foreign).
UNS
G40230;
to
ASTM
l
Characteristics.
One of the two straight molybdenum steels, used almost exclusively for making parts that will be case hardened by carburizing or carbon&riding. When fully quenched, surface hardness is in the range of 40 to 45 HRC. While its hardenability is higher than that of a plain carbon steel of like carbon conte.nt, 4023 is not considered a high-hardenability grade This steel does not have an H counterpart. Grade 4023 is readily forgeable and weldable. Before welding, the carbon equivalent should be checked to determine the need for preheating and postbeating
Forging. Heat to 1245 “C (2275 “F) maximum. Do not forge after the temperature of the forging stock drops below approximately 900 “C ( 1650 “F)
Heat Treating
Normalizing. Heat to Annealing. Annealing
Case Hardening. procedures
l l l l
Processing
4023: Approximate Specimens Reheat temperature OF T
925 “C ( I695 “F). Cool in air
See recommended carburizing. described for 4 I I8H
carbonitriding,
and
Sequence
Forge Normalize Anneal (optional) Rough and semitinish machine Austenitize Case harden Temper Finish machine (carburized parts only)
Practice
is not usually required for this grade. Structures that are well suited to machining are generally obtained by normalizing or by isothermal annealing after rolling or forging. Isothermal annealing may be accomplished by heating to 700 “C ( I290 “F) and holding for 8 h tempering
l l
A322. A33 I. A5 19, A534; SAE 5404. J4 12.5770
Recommended
Recommended l
1125 1125 1575 1700(a) (a) Pseudocarburized
775 775 855 925
Core Hardness of Heat Treated Eardoess, EB O.Wiu. l-in. (25.4mm)
285 293 321 331
223 229 218 155
for 8 hand quenched. Source. Republic
(13.7-mm) rounds
rOU0d.S
Steel
Alloy Steels (1300 through
9700 Series) / 279
4023: Hardness vs Tempering Temperature. average based on a fully quenched
4023:
Approximate
Critical
Points Temperature
lhmsformatioo point
AC, AC, w &I Source: Republic Steel
OC 1350 1540 I-l40 1250
750 840 780 670
structure
Represents
an
Alloy Steels (1300 through 9700 Series) / 279
4024 Chemical Composition.
Similar Steels (U.S. and/or Foreign).
UNS
G40240;
ASTM
A322. A33 I, A5 19; SAE J404. J4 12, J770
Characteristics. One of the two straight molybdenum steels. used almost exclusively for making parts that will be case hardened by carburizing or carbonitriding. When fully quenched, surface hardness is in the range of 40 to 45 HRC. While its hardenability is higher than that of a plain carbon steel of like carbon content. 4024 is not considered a high-hardenability grade. This steel does not have an H counterpart. Grade 4024 is readily forgeable and weldable. Before welding, the carbon equivalent should be checked to determine the need for preheating and postheating. With the exception of a slightly higher allowable sulfur content. grades 4023 and 4024 are identical. This difference in sulfur content provides a slight improvement in machinability, but is not sufficient to significantly impair forgeability or weldability Forging. temperature “F)
Recommended
AI!31 aod UNS: 0.20 to 0.25 C. 0.70 10
0.90 Mn, 0.15 to 0.30 Si. 0.035 Pmax, 0.035 to 0.050 S. 0.20 fo 0.30 MO
Heat to 1245 “C (2275 “F) maximum. Do not forge after of the forging stock drops below approximately 900 “C (I 650
4024: End-Quench Hardenability. Composition: 0.24 C, 0.88 Mn, 0.33 Si. 0.23 MO. Quenched from 925 “C (1695 “F)
Heat Treating
Normalizing. Heat to Annealing. Annealing
Practice
925 “C (1695 “F). Cool in air
is not usually required for this grade. Structures that are well suited to machining are generally obtained by normalizing or by isothermal annealing after rolling or forging. Isothermal annealing may be accomplished by heating to 700 “C ( I290 “F) and holding for 8 h
Case Hardening. tempering process
procedures
Recommended l l l l l l
See recommended carburizing, carbonitriding, and described for4 I l8H. Martempering is also a suitable
Processing
Sequence
Forge Normalize Rough and semifinish machine Case harden Temper Finish machine (carburized parts only)
4024: Hardness vs Tempering Temperature. average based on a fully quenched structure
Represents
an
280 / Heat Treater’s
Guide
4024: Cooling Transformation
Diagram. Composition: 0.24 C, 0.88 Mn, 0.33 Si, 0.23 MO. Austenitized AC,, 825 “C (1520 “F); AC,, 750 “C (1380 “F). A: austenite, F: ferrite, P: pearlite, B: bainite, M: martensite
at 925 “C (1695 “F). Grain size: 8.
280 / Heat Treater’s
4027,4027H,
Guide
4027RH
Chemical Composition. 4027. AK1 and UN.% 0.25 to 0.30 c. 0.70 to 0.90 Mn. 0.15 to 0.30 Si. 0.035 P ma\. 0.040 S max. 0.20 to 0.30 hlo. Uh'S A10270 and SAE/AISI1027H:0.24 to0.30C.0.60to 1.00Mn.0.15 to0.35Si.0.~0to0.30Mo.SAEJ027RH:0.2Sto0.30C,0.70to0.90~ln. 0.15 to 0.35 Si. 0.20 to 0.30 MO Similar ASTM ASTM
Steels (U.S. and/or Foreign). 4027. G40~70; LINS A322. A33 I. AS 19; SAE J-IO-L J-II?. J770.4027H. UNS H-10270; A304 A9 I-l; SAE J 126X. J I868
Characteristics. Often considered horderline between a carhuriring grade and a direct-hardening grade. Commonly used for either cnse-hardening or direct-hardening applications. The hardenability of 4037H is somewhat higher than a carbon steel of equivalent carbon content. although not as high as a I300 grade having the same c&on content. As-quenched hardness (no carburizingj is generally -IS to 48 HRC. Has excellent forgeability, but only fair machinability. Can be welded using alloy steel practice. Preheating and postheating are required because of the relati\el> high carbon equivalent
Forging. forging
Heat to IUS “C (2275 “FL Do not forge after temperature stock drops below approsimatelj 870 “C (1600 OF)
Recommended Normalizing.
Heat Treating
of
Practice
Heat to 900 “C t I650 “FL Cool in air
Annealing. For a predominately psarlitic structure, heat to 855 “C (1570 “F). and cool rapid11 to 750 “C ( I380 “FL then to 610 “C ( I I85 “F) at a rate not to exceed I I “C (20 I-‘F) per h: or heat to 870 “C ( 1600 “F). cool rapidly to 660 “C i I210 “FL and hold for 5 h. For a predominately spheroidized structure, heat to 775 “C ( 1125 “FL cool from 745 “C ( I370 JF) to 640 “C ( I I85 “F) at a rate not to exceed 6 “C ( IO “F) per h: or heat to 775 “C (I 425 “F). cool rapid11 to 660 ;C. ( I?20 “F) and hold for 8 h Direct Hardening. As-quenched
Tempering.
Heat to 855 “C ( IS70 “F). hardness. 12 to 48 HRC. Gas carburizing Reheat to obtain desired hardness
Case Hardening. tempering
and quench in oil. is a suitable process
procedures
See recommended cmhutizing. described for 4 I I8H
carhonitriding.
and
Alloy
Recommended l l l l l l l l
Processing
4027:
Sequence
4027: Isothermal
Transformation
quenched
0.565 l.ccMl 2.ooo -i.ooo
at 925 “C (1695 “F) and fin-
Diagram.
Composition:
9700
Series) / 281
in water
Size round in.
Sourx
4027: Gas Carburizing. Carburized ished at 845 “C (1555 “F)
(1300 through
As-Quenched Hardness
Specimens
Forge Normalize Anneal Rough machine Austenitize or case harden Quench Temper Finish machine
Steels
Bshlrhrm
mm
I-i.35 I ‘5 400 SO.YOO 101.600
Surface
50 HRC 50 HRC 47 HRC X3 HRB
Badness, HRC ‘12 radius
Center
SOHRC 47 HRC 27 HRC 77 HRB
50 HRC 44HRC 27 HRC 7SHRB
Steel
4027: Hardness vs Tempering Temperature. Tempered at indicated temperatures showing effect of time at temperature
0.26 C. 0.87 Mn, 0.26 MO. Austenitized
at 855 “C (1570 “F). Grain size: 7
282 / Heat Treater’s
Guide
4027H, 4028H: Hardenability 900 “C (1650 “F). Austenitize:
hardness Purposes I distance. um 1.5 3 5 7 3 I1 13 I5 20 25 30 35
iardness ‘urposes di!aallce, ‘16 in.
0 1
2 3 4 5 6 8 D 2
Curves. Heat-treating 870 “C (1600 “F)
Limits for Specification Eardness, ERC MXlXiUllUll MillhllUU 52 51 45 40 32 29 26 25 23 22 21
45 41 32 23 20
. .. ..
Limits for Specification Eardness, ERC Maximum Minimum 52 50 46 40 34 30 28 26 25 25 24 23 23 22 22 21 21 20
45 40 31 25 22 20
...
temperatures
recommended
by SAE. Normalize (for forged or rolled specimens only):
Alloy Steels (1300 through
9700 Series) / 283
4027H: End-Quench Hardenability Distance fkom quenched surfsee ‘/,a in. mm
E=-d=s ERC min max
Distance from quenched surface ‘/la in. mm
Badness, ERC max
I
1.58
52
45
I3
20.54
23
2 3 4
3.16 4.74 6.32
50 46 40
40 31 25
I4 I5 16
22.12 23.70 25.28
22 22 21
5
7.90
34
22
I8
28.44
21
6 7 8
9.48 II.06 12.64
30 28 26
20
20 22 24
31.60 34.76 37.92
20 .., . .
9 IO II I2
14.22 15.80 17.38 18.%
25 25 24 23
26 28 30 32
41.08 44.24 47.40 50.56
.__
4027: Gas Carburizing.
Results of 50 tests that represent variation in cation concentration for continuous carburizing. Results were obtained over a 3 to 4 year period of operation using an automatic dew point controller
4927: Cooling Curve. Half cooling timeSource:
Datasheet
l-91, Climax Molybdenum
Company
284 / Heat Treater’s
Guide
4027RH: Hardenabilitv Austenitize:
Hardness Purposes J distance, 916 in.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 1.5 16 18 20 22 24 26 28 30 32
Hardness Purposes J distance. mm
1.5 3 5 I 9 11 13 15 20 25 30 35 40 45 50
Curves. Heat-treating
870 “C (16bO “F)
Limits for Specification Eardness, hleximum
HRC hlinimum
51 48 43 31 32 28 26 24 23 22 22 21 21 20 .
46 42 34 28 24 22 20 ... .
... ... ... ... ...
... ... ... ... ...
.
.
“.. . Limits for Specification Hardness, ARC Maximum hlinimum
51 48 42 35 29 26 24 23 21
.
46
42 33 26 23 20
.
recommedned
by SAE. Normalized
(for forged or rolled specimens
only: 900 “C (1650 “F).
1
Alloy Steels (1300 through
alloy steel. Chemical composition: 0.28 C, 0.25 Si, 0.86 Mn, 0.020 P, 0.028 S, 0.062 Cr, 0.026 Ni,,0.23 heat; bar stock austenitized at 870 “C (1600 “F) 20 min
4027: CCT Diagram. Constructional MO, 0 .11 Cu. Acommercial
9700 Series) / 285
Alloy Steels (1300 through
9700 Series) / 285
4028,4028H Chemical
Composition. 4028. AISI and UNS: 0.3 to 0.30 C. 0.70 too.90 hZn.0.15 to0.30Si.0.035 Pmax.0.035 toO.OSOS.0.20 too.30 Mo. UNS H10280 and SAE/AISI 4028H: 0.24 to 0.30 C. 0.60 to I .OO Mn. 0.035 to 0.050 S. 0.15 to 0.35 Si. 0.X to 0.30 hlo Similar ASTM ASTM
1JNS G-tO280: Steels (U.S. and/or Foreign). 4028. A333. A33 I. AS 19: SAE J-IO-I. 1113. J770.1028H. LINS H-10280: A304 SAE J-t07
Direct Hardening. quenched hardness, suitable process
Tempering.
Heat tn I245 “C (2275 “F). Do not forge after temperature forging stock drops belo\\ approxtmately 870 ‘C ( 1600 “F)
Recommended
Heat Treating
of
Practice
Heat to 900 “C (l6SO “F). Cool in air
tempering
l l
Annealing.
For a predominately pearlitic structure. heat to 855 “C t IS70 “F). cool rapidI) to 750 “C (I 380 “F). then to 870 “C ( 1600 “F) at a rate not to exceed I I “C (20 “F) per h: or heat to 870 “C ( 1600 “F). cool rapidly to 660 “C (I 220 “F), and hold for 5 h. For a predominateI> spheroidized structure. heat to 775 “C ( I-415 “FL cool from 7-U “C (I 370 “F) to 640 “C
procedures
Recommended l
l l l l l
Heat to 85s “C ( IS70 “F) and quench in oil. ASappro\imatelq 12 to 48 HRC. Mat-tempering is a
Reheat to obtain the desired hardness
Case Hardening.
Forging.
Normalizing.
t I I85 ‘F) at a rate not to exceed 6 “C t IO “F) per h: or heat to 775 “C (1425 “F). cool rapidly to 660 “C t I220 “F). and hold for 8 h
See recommended carbutizing. described for -I I I8H
Processing
Forge Normalize Anneal Rough machine Austenitize or case harden Quench Temper Finish machine
Sequence
carbonitriding.
and
288 / Heat Treater’s
1 2 3 4 5 6 7 8 9 10 II 12
1.58 3.16 4.74 6.32 7.90 9.48 11.06 12.64 14.22 15.80 17.38 l8.%
Guide
52 SO 46 40 34 30 28 26 2s 2s 24 23
45 40 31 25 22 20 __.
_._ .
13 14 IS I6 I8 20 22 24 26 28 30 32
20.54 22.12 23.70 25.28 28.44 31.60 34.76 37.92 41.08 44.24 41.40 50.56
23 22 22 21 21 20 . .
4028: Liquid Carburizing. 1'l/32 in. outside diameter by 6 3/4in. Oil quenched. Carburized at the temperatures indicated
4028, 4028H: Hardness vs Tempering Temperature. Represents an average based on a fully quenched structure
288 / Heat Treater’s Guide
4032,4032H Chemical Composition.
4032. AISI: 0.30 to 0.35 c, 0.70 to 0.90
Mn.0.20to0.35Si,0.035Pmax,0.040Smax,0.20to0.30hlo.UNS:0.30 to0.35C. 0.70to0.90Mn.0.035 Pmax.0.040S max.0.15 to0.30Si.0.20 to 0.30 MO. UNS H40320 and SAE/AISI 40328: Nominal. 0.29 to 0.35 C. 0.60 to 1.00 Mn. 0.15 to 0.35 Si. 0.20 to 0.30 Mo
Similar Steels (U.S. and/or Foreign). 4032. ASTM A322; FED QQ-S-00629 (FS4032); UNS H40320: ASTM A304; SAE J I268
UNS G40320; SAE J404,J412. J770.4032H.
tions carbonitriding is excellent
has been applied
to 4032H. Forgeability
of this grade
Forging. forging
Heat to 1235 “C (2275 “F). Do not forge after temperature stock drops below approximately 870 “C (1600 “F)
Recommended Normalizing.
Heat Treating
Practice
Heat to 900 “C (I 650 “F). Cool in air
Annealing.
Characteristics. With a carbon content that slightly overlaps 4027H and with an otherwise identical composition, the general characteristics of 4032H and 4027H are the same. The hardenability pattern for 4032H resembles that of4027H. although the curves for 4032H are moved slightly upward compared with those for 4027H because of a higher nominal carbon content. Fully hardened 4032H wiU provide a surface hardness of approximately 48 HRC or slightly higher. Grade 4032H is less weldable and has a slightly lower machinability than 4027H because of a higher nominal carbon content. Direct hardening rather than case hardening is used for 4032H. although for special applica-
of
For a predominately pearlitic structure. heat to 855 “C (1570 “F). cool rapidly to 750 “C (I 380 “F), then to 640 “C (I I85 “F) at a rate not to exceed I I “C (20 “F) per h; or heat to 870 “C (I 600 OF), cool rapidly to 660 “C (1220 “F), and hold for 5 h. For a predominately spheroidized structure, heat to 775 “C (1425 “F). cool from 745 “C ( 1370 “F) to 640 “C (I I85 “F) at a rate not to exceed 6 “C (IO “F) per h; or heat to 775 “C (1425 “F’), cool rapidly to 660 “C ( I220 “F), and hold for 8 h
Hardening. Heat to 855 “C (I 570 OF). and quench in oil. Carbonitriding is a suitable process Tempering.
Reheat to obtain the desired hardness
Alloy Steels (1300 through 9700 Series) / 287
Recommended Forge l Normalize . t%‘uE.d l Rough machine l Austenitize l Quench l Temper l Finish machine l
Processing
Sequence
4032, 4032H: Hardness vs Tempering Temperature. Represents an average based on a fully quenched structure
4032: Continuous Cooling Transformation Diagram. Composition: 0.32 C, 0.80 Mn, 0.025 P, 0.020 S, 0.30 Si, 0.28 MO. Austenitized at
1
288 / Heat Treater’s
4032H: Hardenability (1650 “F). Austenitize:
Hardness Purposes I distance,
mm 1.5 3 i
7 2 I1 13 I.5 !O 15 $0 15 ul 15 50
Hardness Purposes I distance, V,6 in.
5 5 > IO
I1 I2 I3 I4 15 I6 18 !O !2 !4 !6 !8 10
Guide
Curves. Heat-treating 870 “C (1600 “F)
Limits for Specification Hardness,
Maximum
HRC
Minimum
51 55 51 44 36 32 29 21 24 23 23 22 21 20
50 46 34 21 24 22 20
. .
Limits for Specification Hardness, HRC Maximum Minimum 57 54 51 46 39 34 31 29 28 26 26 25 24 24 23 23 23 22 22 21 21 20
50 45 36 29 25 23 22 21 20
.
. ..” . . .
temperatures
recommended
by SAE. Normalize (for forged or rolled specimens
only): 900 “C
1
Alloy Steels (1300 through 9700 Series) / 289
4032H: End-Quench Distance from quenched surface
916in. I 2 3 -I 5 6
1 8 9 IO II I3
Hardenability Distance from quenched surface
Hardness, ERC
Hardness,
mm
max
min
!$6 in.
mm
HRC mas
1.58 3.16
57 5-l
SO 1s 36 19 15 23 22 21 20
13 I-1 IS I6 I8 20 22
20.51 22.11 23.10 25.28 28.44 31.60
21 2-l 23 23 '3 2
31.16
22
1-l
31.9). 1108 44.21
21 21 20
1.11
51
6.37
46 39 31 31 29 28 26 26 25
1.90 9-18 Il.06 12.64 11.22 IS.80 1138 I8.%
::'
26 28 30
11.40
32
50.56
Alloy Steels (1300 through
9700 Series) / 289
4037,4037H Chemical Composition. 4037. AISI and UNS: 0.35 10 0.40 C. 0.70 to 0.90 Mn. 0.15 to 0.30 Si. 0.035 P max. 0.040 S max. 0.20 to 0.30 hlo. UNS H40370 and SAE/AISI 4037H: 0.34 to O.-l I C. 0.60 to I .OO hln. 0. IS to 0.35 Si. 0.70 to 0.30 hlo
Hardening. Heat to 845 “C ( IS55 “F). and quench in oil. Carbonitriding is a hardening process. In aerospace practice. parts are austenitized at 815 “C t IS55 “F). and quenched in oil or hater
Similar
Tempering.
Steels (U.S. and/or
Foreign).
ASTM A322. A33 I. AS 19, AS-+7: WE H40370: ASTM A30-I: SAE J 1368
UNS G-10370: 4037. J-KM. J-Ill. 5770. 1037H. UNS
Characteristics.
A medium-carbon. IOU-alloy steel that can be hardened to approximately SO HRC or slightly higher, provided it is properl! quenched. and the carbon is on the high side of the allouable range. The hardenabilib pattern is similar to that of other carbon-molybdenum steels (4077H and 103ZH) except that the curves move up\\ard hecause of the higher carbon content. Has excellent forgeability, but neldahility (princepall? m terms of susceptibility to weld cracking) decreases as carbon content mcrcasrs
Rehsat to the temperature hardness. See table
Recommended l l l l l l l
Forging. forging
Heat to I?30 “C ( X-IS “FL Do not forge after temperature stock drops beIon approrimately 85.5 “C ( IS70 OF)
Recommended
Heat Treating
of
Practice
Normalizing.
Heat to 870 “C (1600 ‘FL Cool in air. In aerospace practice, parts &arenormalized at 900 “C ( 1650 “F)
Annealing. For a predominately pearlitic structure, heat to 845 “C ( IS55 “F). cool rapidly to 745 “C ( I370 “FJ. then to 630 ‘C ( I I70 “F) at a mte not to exceed I I “C (20 “F) per h; or heat to 845 “C ( IS55 “F), cool rapidI> to 660 “C ( IX0 “F). and hold for 5 h. For a predominately spheroidired structure. heat to 760 “C ( I100 “F). cool from 7X “C ( 1370 “F) to 630 “C t I I70 “F) at a rate not to esceed 6 “C ( IO “F) per h: or heat to 760 “C ( I400 “F). cool rapidly to 660 “C (I 220 “F). and hold for 8 h. ln aerospace practice. pans are annealed at 815 “C ( IS55 OF). Pans are cooled to below -WI ‘% (750 “F) at a rate not to exceed I IO “C i200 OF) per h
l
Processing
required
to provide
the desired
Sequence
Forge Normalize Annsal Rough machine Austenitize Quench Temper Finish machine
4037: Suggested practice)
Tempering
Temperatures
(Aerospace
Tensile Strength Ranges 86010 1035 to 1175 to 1240 to 1035 MPa 1175 MPa 1240 hlPa 1380 blPa 620 to 860 MPa (90to 125ksi) (125to 15Ok.G) (150to 17Ok.G) (170 to 180 ksi) (180 to200 ksi) 595 ‘Cl II I IIOO”F, 65O”Cfh) (1200°F)
s-lo ‘C (lCMXI’;FI 595 ‘C IIIOO”Fl
(a) Quench m oil or pol!nw
195 ‘C r92S ‘:‘F) 5-u) “C I IOW’F,
440 “C (825 “I=) -170“C (875 “F)
Ib) @ench in ~awr. Source: AMS 275911
370 “C 1700°F) 3x5 “C (725 “FJ
290 / Heat Treater’s
Guide
4037H: End-Quench Hardenability Distance hm quenched
Diktancefrom
ERC
surface
v,l/lain. I
2 3 4 5 6 7 8 9 10 II I2
mm
I .58 3.16 4.74 6.32 7.90 9.48 11.06 12.64 14.22 15.80 17.38 18.%
max
Earducss,
quenched
Bardn-9
ERC
surface min
‘/la
in.
mm
max
59
52
13
20.54
26
57 54 51 45 38 34 32 30 29 28 27
49 42 35 30 26 23 22 21 20
14 15 I6 18 20 22 24 26 28 30 32
22.12 23.70 25.28 28.44 31.60 34.76 37.92 41.08 4.2-l 47.40 50.56
26 26 35 25 25 2.5 24 24 24 23 23
4037: Cooling Curve. Source: Datasheet
l-21 6. Climax Molybdenum
Company
Alloy Steels (1300 through
4037: Isothermal Transformation
Diagram. Composition:
0.35 C, 0.80 Mn, 0.25 MO. Austenitized
4037: Hardness vs Tempering Temperature. Normalized at 870 “C (1600 “F). Quenched from 845 “C (1555 “F) and tempered in 56 “C (100 “F) intervals in 13.716 mm (0.540 in.) rounds. Tested in 12.827 mm (0.505 in.)
9700 Series) / 291
at 855 “C (1570 “F). Grain size: 7
4037: Hardness vs Tempering Time and Tempering Temperature. Tempered at temperatures indicated
292 / Heat Treater’s
4037H: Hardenability (1800 “F). Austenitiz&
Hardness Purposes I distance, nm
1.5 3 5 7 9 11 13 15 20 25 30 35 40 45 50
rlardness Purposes I distance, 46in.
1 3 > 10
I1 12 13 14 15 16 18 ,O 12 24 16 23 30 32
Guide
Curves. Heat-treating temperatures 845 “C (1555 “F) -
Limits for Specification Hardness, HRC hlaximum hliuimum
59 57 54 49 41 35 32 30 21 26 25 25 25 24 23
52 50 42 32 27 24 21 20
.
Limits for Specification Eardness, HRC Maximum hlinimum
59 51 54 51 45 38 34 32 30 29 28 21 26 26 26 25 25 25 25 24 24 24 23 23
52 49 42 35 30 26 23 22 21 20
. ..
recommended
by SAE. Normalize (for forged or rolled specimens
only): 870 “C
Alloy
Steels (1300 through
9700 Series) / 293
4037: CCT Diagram. Constructional alloy steel composition: 0.41 C, 0.74 Mn, 0.008 P, 0.032 S, 0.28 Si, 0.014 Ni, 0.034 Cr, 0.21 MO, 0.065 Cu. Acommercial heat; barstock steel was austenitized for20 min at 845 “C (1555 “F). Source: Datasheet l-21 6. Climax Molybdenum Company
Alloy
Steels (1300 through
9700 Series) / 293
4042,4042H Chemical
Composition. 1042. AISI: 0.40 to 0.15 C. 0.70 to 0.90 Mn.0.20 too.35 Si.O.040 Pmax.0.040S max.0.20 too.30 hlo. UNS: 0.40 to0.3.S C. 0.70 to 0.90 hln. 0.035 Pmax. 0.010 S max. 0. IS too.30 Si. 0.30 to 0.30 MO. UNS H40420 and SAE/AISI JOJZH: 0.39 to 0.46 C. 0.60 to 1.00 Mn. 0.15 to 0.3s Si. 0.20 to 0.30 hlo Similar ASTM ASTM
Steels (U.S. and/or Foreign). 1042. A322, A33 I, A5 19: SAE J-10-1. J312.J770.1042H. A3O-l; SAE J I368
UNS G-10-110: LINS H-tO-tX
Characteristics. Has characteristics that closeI) parallel those of the other medium-carbon. molybdenum-alloy steels (see -1027H and -1037H). As the carbon content increases. the as-quenched hardrwss mcreases. Depending to some extent upon the precise carhon content. fully hardened -1012H has a surface hardness of approsimatel> 55 HRC. Forgeobilit> of this grade is escellent. but welding is difficult bscause of the difticult) in producing crack-free welds Forging.
Heat to 1230 ‘-‘C (2245 “FL Do not forge after temperature forging stock drops helow approximately 855 “C (IS70 “F)
Recommended
Heat Treating
Practice
of
Annealing.
For a predominately pwlitic structure. heat to 845 “C (1555 “FL cool rapidI\ to 745 “C (I 370 “F). then to 630 “C (I 170 “F) at a rate not to exceed I I ‘C t 20 “F) per h: or hcu to 8-15 “C ( I555 “F), cool rapidly to 660 ‘C. (I220 OF). and hold for S h. For a predominately spheroidized structure. heat to 760 “C I 1400 “F). cool from 735 “C ( I370 “F) to 630 “C (I 170 “F) at a r;ltc not to eucred 6 “C (IO “F) per h; or heat to 760 “C (I400 “F), cool rapidI> to 660 “C ( I220 “F). and hold for 8 h
Hardening. Heat to 845 “C ( I555 OF), and quench in oil. Carbonitriding is a suitable process Tempering.
Recommended l l l l l l l
Normalizing.
Heat to 870 “C I 1600 “F). Cool in air
Reheat to the temperature
required
to provide
h,udrwss
l
Forge Nomlalizc Anneal Rough machine Austrnitirz Quench Tsmpcr Finish machins
Processing
Sequence
the desired
294 / Heat Treater’s
4042: Continuous
Guide
Cooling Transformation
Diagram. Composition:
0.40 C, 0.80 Mn, 0.025 P, 0.020 S, 0.30 Si, 0.26 MO. Austenitized
at
810 “C (1490 “F)
4042: Isothermal Transformation
Diagram. Composition:
0.42 C, 0.20 Mn, 0.21 MO. Austenitized
at 870 “C (1600 OF). Grain size: 5 to 6
Alloy Steels (1300 through
I 2 3 4 5 6 7 8 9 IO II I2
I .58 3.16 4.14 6.32 7.90 9.48 II.06 12.64 14.22 15.80 17.38 l8.%
62 60 58 55 50 45 39 36 34 33 32 31
5.5 52 48 40 33 29 27 26 25 24 24 23
I3 I4 I5 I6 I8 20 22 24 26 28 30 32
20.54 22.12 23.70 25.28 28.44 31.60 34.76 37.92 41.08 44.24 47.40 50.56
30 30 29 29 28 28 28 27 27 27 26 26
9700 Series) / 295
23 23 22 22 22 21 20 20
4042: Hardness vs Tempering Temperature. Normalized at 870 “C (1600 “F). Quenched from 845 “C (1555 “F) in oil and tempered in 56 “C (100 “F) intervals in 13.716 mm (0.540 in.) rounds. Tested in 12.827 mm (0.505 in.) rounds. Source: Republic Steel
296 / Heat Treater’s
4042H: Hardenability (1600 “F). Austenitize:
Hardness Purposes I distance, mm
1.5 3 5 7 9 11
13 15 20 25 30 35 40 45 50
Hardness Purposes I distance, V,6 in.
i 3 IO
11 12 13 14 15 I6 18 !O !2 !4 !6 !8 10 $2
Guide
Curves. Heat-treating 845 “C (1555 “F)
Limits for Specification Eardness, Maximum
HRC hlinimum
55 53 47 36 30 27 25 24 23 22 21 20
62 61 58 54 48 40 36 33 31 29 28 28 27 27 26
Limits for Specification Hardness, HRC Maximum hlinimum
62 60 58 55 50 45 39 36 34 33 32 31 30 30 29 29 28 28 28 27 27 27 26 26
55 52 48 40 33 29 27 26 25 24 24 23 23 23 22 22 22 21 20 20 .
temperatures
recommended
by SAE. Normalize (for forged or rolled specimens
only): 870 “C
Alloy
Steels (1300 through
9700 Series) / 297
4047,4047H Chemical Composition. 4047. AISI and UN% O.-IS to 0.50 C. 0.70 to 0.90 Mn, 0.15 to 0.30 Si, 0.035 P max. O.O-iO S max. 0.20 to 0.30 Mo. UNSH40470and SAE/AISI4047H:0.1-1toO.S1 C.O.60to l.OOMn.O.lS to 0.35 Si. 0.20 lo 0.30 MO Similar ASThl ASTM
Steels (U.S. and/or
Foreign).
4047.
A322. A33 I. AS 19: SAE J-W. JA II. J770.4047H. A30-k SAE J I268
UNS G10-170; UNS H-lO-I70:
Characteristics.
W7H. which ma) have a carbon content of up to 0.51. borders on u hat may be considered high-carbon steel and is sometimes used in applications that require spring grades. The hardenability of 11U7H exhibits a pattern veq similar to the lower or medium-carbon grades of the -lOXX series. although both the minimum and masimum tunes are shifted further upward on the hardenability chart because of the higher carbon content of -IO-L7H. As-quenched hardness of fully hardened -W7H should be near S5 HRC or slightI) higher. depending upon the precise carbon content. Readily forged. but not r&omm;nded fir \;*elding. In addition to direct hardening and tempering. 10-17H is well adapted to heat treating bq the nustempering process
Annealing.
For a predominately pearlitic structure, heat to 830 “C (IS25 “F). cool fairlq rapidlv to 730 “C ( 1350 “Fj. then to 630 “C ( I I70 “F) at a rate not to exceed I I ;C (20 “F) per h: or cool fairly rapidly from 830 “C (IS25 “Fj to 660 “C ( I220 “F). and hold for 5 h. For a predominately spheroidized structure, heat to 760 “C ( 1400 “F). cool fairly rapidly to 730 “C t I350 “F), then to 630 “C ( I I70 “F). at a rate not to exceed 6 “C (IO “F) per h; or heat to 760 “C ( 1100 “F). cool Fairly rapidly to 650 “C ( I200 “F). and hold for 9 h
Hardening. Austenitize at 830 “C ( I525 OF). and quench in oil. Austempering and cwbonitridinp are suitable processes Tempering.
forging
Heat to I220 “C (2325 “F). Do not forge after temperature stock drops belo\+ approsimntel) 8-lS YI ( 1555 “F)
of
Heat Treating
Practice
Recommended l
l l
l l
Normalizing.
Heat to 870 “C (1600 “FL Cool in air
4047: Isothermal Transformation
Diagram. Composition:
to provide
the desired
Austenitize at 845 “C (I555 OF), quench in agitated molten salt at 315 “C (655 “F). hold for 2 h and cool in air. Resulting hardness should be 15 to SO HRC. No tempermg is required
l
Recommended
required
Austempering.
l
Forging.
Reheat to the temperature
hardness
l
Processing
Sequence
Forge Normalize Anneal Rouph machine Austenitize (or austemper) Quench (or austemper) Temper (or austemper) Finish machine
0.48 C. 0.94 Mn. 0.25 MO. Austenitized
at 815 “C (1500 “F). Grain size: 6 to 7
298 / Heat Treater’s
4047: Continuous
Guide
Cooling Transformation
Diagram. Composition:
810 “C 11490 “Fb
4047H: End-Quench Hardenability Diitance from quenched surface i6 in. mm
Eardoess, RRC max min
Distance from quenched surface
‘/16h.
mm
Hardness, ERC max min
1 2 3 4 5 6 7 8 9 10 11
1.58 3.16 4.74 6.32 7.90 9.48 11.06 12.64 14.22 15.80 17.38
64 62 60 58 55 52 47 43 40 38 37
51 55 50 42 35 32 30 28 28 27 26
13 14 15 16 18 20 22 24 26 28 30
20.54 22.12 23.70 25.28 28.44 31.60 34.76 37.92 41.08 44.24 47.40
34 33 33 32 31 30 30 30 30 29 29
2.5 25 25 25 24 24 23 23 22 22 21
12
18.96
35
26
32
50.56
29
21
0.48 C, 0.80 Mn, 0.025 P, 0.020 S, 0.25 Si, 0.26 MO. Austenitized
at
Alloy
Steels (1300 through
9700 Series) / 299
4047: Cooling Transformation
Diagram. Composition: 0.51 C, 0.81 Mn. 0.25 Si, 0.26 MO. Austenitized at 845 “C (1555 “F). Grain size: 8. AC,, 790 “C (1455 “F); AC,, 745 “C (1370 “F). A: austenite, G: ferrite. P: pearlite, B: bainite, M: martensite. Source: Bethlehem Steel
4047: Hardness vs Tempering Time and Tempering Tempsrature. Tempering temperatures indicated
300 / Heat Treater’s
Guide
4047: Variations in Depth of Hardening. Tempered 1 h at indicated temperatures. (a) 12.7 mm (l/2 in.) diam cylinders; (b) 25.4 mm (1 in.) diam cylinders: (c) 38.1 mm (1’12 in.) diam cylinders
4047: Microstructures. (a) 2% nital. 110x. Hot rolled steel bar. 28.6 mm (15s in.) diam with a mill defect (a sliver of metal) at the surface, folded over oxide (dark gray). Primarily ferrite, resulting from decarburization, with patches of fine pearlite (dark). (b) 2% nital. 550x. Cold drawn steel bar, 23 mm (29/32 in.), mill annealed; longitudinal section. Somewhat segregated ferrite (white) and fine pearlite (dark) caused difficulty in machining (drilling) (continued)
Alloy
Steels (1300 through
9700 Series) / 301
4047: Microstructures (continued). (c) 2% nital, 550x. Hot rolled steel 26.2 mm (1 l/32 in.) diam: longitudinal section taken at midradius. Acicular ferrite and upper bainite. resulting from rapid cooling from rolling temperature. Large dark areas are pearlite. (d) 2% nital, 550x. Steel forging, 12.7 mm (‘12 in.) thickness, air cooled from forging temperature of 1205 “C (2200 “F); longitudinal section. Plates of ferrite (white) and fine pearlite (dark). (e) 2% nital, 500x. Steel forging. Longitudinal section, 15.9 mm (5/8 in.). Austenitized at 830 “C (1525 “F), cooled to 665 “C (1230 “F) and held 6 h. furnace cooled to 540 “C (1000 “F). air cooled. Ferrite (white) and lamellar pearlite (dark)
4047: Cooling
Curve. Half cooling time. Source: Datasheet
l-21 9. Climax Molybdenum
Company
302 / Heat Treater’s
Guide
4047H: Hardenabilitv Curves. Heat-treatina temperatures recommended by SAE. Normalize (for forged or roiled specimens only): 870 “C (1600 “F). Austenitizk 845 “C (1555 “F) Hardness Purposes 1 distance.
mm 1.5 3 5 7 3 11 13 15 20 25 30 35 40 15 50
Hardness Purposes J distance, ‘$6 in. 1 2 3 1 5 5 7 3 3 10 11 12 13 14 15 16 18 20 !2 14 !6 !8 30 52
Limits for Specification Flardness, mc MilliDlUIU Maximum 64 63 60 57 53 48 43 39 34 33 31 30 30 29 29
57 55 49 39 33 30 28 21 25 24 24 23 23 22 21
Limits for Specification Eardnes, ERC Maximum Minimum 64 62 60 58 55 52 41 43 40 38 31 35 34 33 33 32 31 30 30 30 30 29 29 29
57 55 50 42 35 32 30 28 28 27 26 26 25 25 25 25 24 24 23 23 22 22 21 21
Alloy Steels (1300 through
4047: CCT Diagram. Constructional
9700 Series) / 303
alloy steel. Chemical composition: 0.48 C, 0.23 Si, 0.78 Mn, 0.005 P: 0.020 St 0.06 Cr, 0.012 Ni, 0.25 MO, 0.015 Cu. Bar stock from commercial heat was used in study. Steel was austenitized at 845 “C (1555 “F) 20 min. Source: Datasheet l-219, Climax Molybdenum Company
Alloy Steels (1300 through 9700 Series) / 303
4118,4118H, Chemical Composition.
4118RH 4118. AISI and UNS: 0. I8 to 0.23 C. 0.70
to 0.90 Mn. 0.15 to 0.30 Si. 0.035 P max. 0.040 S max. 0.40 to 0.6OCr. 0.08 to 0. I5 MO. UNS If41180 and SAE/AISI 4118H: 0. I7 to 0.23 C. 0.60 to 1.00 Mn, 0.15 to 0.35 Si. 0.30 to 0.70 Cr. 0.08 to 0.15 MO. SAE 4118RI-I: 0.18 to 0.23 C, 0.70 to 0.90 Mn. 0.15 to 0.35 Si. 0.10 to 0.60 Cr. 0.08 to 0.15 MO
Similar Steels (U.S. and/or Foreign). 4118.
UNS G-l I 180: SAE 5404. J412. J770. 4118H. UNS
ASTM A322, A33l. A505, ASl9; H-II 180: ASTM A304: SAE Jl268.51868;
Characteristics.
ASTM
A913
Low-ahoy steel which is used extensively for case hardening applications. conventional carhurizing as well as carhonitriding. As can be observed in the hardenability data for -II ISH, the hardenability differs little from that of a comparable 1000 series steel. The chromium addition in 41 ISH little more than offsets the decrease in molybdenum content. Depending somewhat upon the precise carbon content of 41 IgH. the as-quenched surface hardness will be approximately 38 HRC or slightly higher. Forgeahility is excellent, but machinability is only fair. 41 I8H can be readily welded. although before any welding is attempted the carbon
equivalent observed
should
Forging.
Heat to I?-!5 “C (2275 “F) maximum. Do not forge after of forging stock drops below approximately 870 “C (1600 “F)
temperature
be determined.
Recommended Normalizing.
and recommended
Heat Treating
Heat to 925 “‘C (I695
welding
practices
Practice
“F). Cool in air
Annealing. Not usually required for this grade. Structures that are well suited to machining are generally obtained by normalizing or by isothermal annealing after rolling or forging. Isothermal annealing may be accomplished hy heating to 700 “C ( 1290 “F) and holding for 8 h Direct Hardening. While applications for 41 l8H seldom require direct hardening. it can be accomplished by austenitizing at 900 “C (1650 “F) and quenching in oil. Ion nitriding, gas nitriding, carbonitriding. and gas or liquid salt bath carburizing are suitable processes Carburizing. II l8H responds readily to any gas or liquid salt bath carburizing processes. The most widely used gas carburizing procedure is described helow:
304 / Heat Treater’s Guide l
l
l l
Heat to 925 “C ( I695 “F) in a gaseous atmosphere with a carbon potential of approximately 0.90%, for the required time. About 4 h at temperature is required to attain a case depth of 1.37 mm (0.050 in.) Decrease temperature to 845 “C ( 1555 “F). decrease carbon potential slightly, and hold for a I h diffusion cycle Quench in oil Temper at I SO to I75 “C (300 to 335 “F). Higher tempering temperatures may be used if some case hardness can be sacrificed
Other carburizing cycles may be used. One cycle consists of slo\r cooling from the carburizing temperature, then reheatmg to 845 “C ( IS55 “F) and oil quenching. However. this cycle is used less FrequentI) because it hastes energy and takes too much ttme. Double treatments Hhich Mere extensively used at one time are all but obsolete. Depth of carburized cases depends upon time and temperature. The rate of carburization can be increased exponentially by increasing the carburizing temperature from 925 “C (I695 “F) to 1040 “C t 1905 “F) or even higher. However, the economics must be considered. As a rule. the rate of deterioration of conventional carburizing furnaces becomes intolerable as temperatures exceed 925 “C (1695 “F). Using a vacuum furnace has proved to be the most practical answer to carburizing at temperatures as high as 1095 “C (2005 “F).
Carbonitriding.
3 I I8H is widely used in applications involt ing small hardware items where only a thin. file hard case is required. In carbonitriding. the parts &are heated in a carburiring atmosphere I$ ith an addition of approximately IO vol % anhydrous ammonia. Carbonitriding temperatures are most often within the range of 790 to 815 “C (I-155 to IS55 “F) A common carbonitriding cycle for lou-carbon alloy steels. such as 3 I I8H, is to carbonitride at 8 IS “C ( IS00 “F) for 45 nun and quench in oil. This results in a tile hard case approximately 0. I27 mm (0.005 in. j in depth. Somewhat deeper cases may be obtained by increasing the temperature. the
4118H: End-Quench
Distance from quenched surface 916 in. mm
I 1 3 -I 5 6 7 8 9 IO II I2
Hardenability
Aardoess, ERC max min
IS8
48
3.16 4.7-I 6.32 7.90 9.48 II.06 12.64 l-l.32 IS.80 17.38 I8.%
46 II 3s 31 28 27 26 2-t 13 22 21
II 36 27 2.3 10
Distance from quenched surface I&j in. mm I3 i-l I5 I6 I8 20 22 2-t 26 ‘8 30 32
Rardness HRC max
time. or both. Houever. this process is designed especially for developing thin cases on small parts which \vill not be subjected to such finishing operations as grinding. Tempering of carbonitrided parts is recommended ( IS0 to 260 “C, or 300 to 500 “F), because it decreases the tendency for brittleness, although the vast majority of carbonitrided parts are placed in service without tempering
Recommended l l l l l l l
Processing
Sequence
Forge Normalize AMC~ (optional) Rough and semilinish machine Case harden or direct harden Temper Finish machine tcarbunzed parts only)
4118: Diametral Dimensions of a Pinion Before and After Carburizing and Hardening. Carburlzed at 885 “C (1625 “F), oil quenched
from 830 “C (1525
“F), tempered
at 185 “C (365 “F).
Depth of case, 1.016 to 1.270 mm (0.040 to 0.050 in.). 60 HRC minimum. (a) Before treatment. (b) Aftertreatment. (c) Differential drive pinion gear
Alloy Steels (1300 through 9700 Series) / 305
4118, 4118H: Hardness vs Tempering Temperature. Represents an average based on a fully quenched structure
4118H:
As-Quenched
Specimens
were quenched
Hardness in oil
Size round in.
mm
Surface
Aardness ‘12 radius
Center
33 HRC 12 HRC
33 HRC 20 HRC
33 HRC 20 HRC
87 88 HRB
87 88 HRB
85 87 HRB
4118H: Microstructures. (a) 4% nital, 250x. Steel bar, gas carburized for 8 h at 925 “C (1695 “F), quenched in oil, heated to 845 “C (1555 “F) and held for 15 min, quenched in oil, tempered for 1 h at 170 “C (340 “F). Completely decarburized surface layer (white). Structure identified in (b). (b) 4% nital, 500x. Same as (a), but a higher magnification. Shows surface oxidation (dark at top), decarburized surface layer (ferrite), transition zone consisting of ferrite plus low-carbon martensite. and matrix of tempered martensite and retained austenite. (c) 4% nital, 100x. Carburized, hardened, and tempered same as (a), but shows only partial decarburization near surface because specimen previously contained precipitated intergranular carbide particles. Case matrix same as (b). (d) 4% nital, 250x. Steel tubing, gas carburized 5 h at 925 “C (1695 “F) and oil quenched, then hardened and tempered same as (a). Specimen shows the effect of localized overheating (burning) of the carburized surface during grinding. See (e) and (f). (e) 4% nital. 100x. Same as (d), but with less severe grinding burn. As in (d), the light-etching surface layer is untempered martensite and retained austenite (not distinguishable here), and adjacent dark-etching zone is self-tempered martensite. See (f). (f) 4% nital, 500x. Same as (d) and (e), except grinding burn is extremely slight. White surface layer (untempered martensite) is barely perceptible, and the underlying layer of self-tempered martenslte is shallow. As in (d) and (e), matrix is tempered martensite
306 / Heat Treater’s
Guide
4118H: Hardenability
Curves. Heat-treating
(1700 “F). Austenitize:
925 “C (1700 “F)
iardness hrposes I distance, urn
iardness ‘urposes distance, $6 in.
Limits for Specification Eardness, ERC Maximum Minimum
Limits for Specification Eiardnes, ERC Maximum Minimum 48 46 41 35 31 28 21
0 I 2 3 4 5
2s 24 23 22 21 21 20
41 36 27 23 20
temperatures
recommended
by SAE. Normalize (for forged or rolled specimens
only): 925 “C
Alloy Steels (1300 through 9700 Series) / 307 4118:
Carburizing, Single Heat Results
Specimens contained 0.21 C, 0.80 Mn, 0.008 P, 0.007 S, 0.27 Si, 0.16 Ni, 0.52 Cr, 0.08 MO; grain size was 6 to 8; critical points included AC,, 750°C (1380°F); Ac3, 825°C (1520°F); Ar,, 775°C (1430°F); Ar,, 680°C (1260 “F); 14.4-mm (0.565-in.) rounds were treated; 12.8-mm (0.505in.) rounds were tested
Recommended For maximum
practice
hsile ksi
streagtb MPa
61 62 62
0.063 o.tN7 0.047
1.600 1.19-l 1.19-l
177.5 I-13.0 126.0
1223.8 985.6 868.7
131.0 93.5 63.5
903.2 644.7 437.8
9.0 17.5 21.0
42.3 41.3 42.4
352 293 241
57 56 56
0.063 0.047 0.047
1.600 1.19-l 1.19-l
177.0 138.0 120.0
1220.4 961.5 827.4
130.0 89.5 63.0
8%.3 617.1 -13-t.4
13.0 17.5 22.0
48.0 41.9 48.9
341 277 229
Eardness, EIB
case hardness
Direct quench from pot(a) Single quench and temper(b) Double quench and temprk) For maximum
mm
Eardness, ERC
Yield strength 0.2 % offset bi hIPa
Core properties Elongation in2in. Reduction @mm), 9% ofarea, 5%
case properties Depth in.
core toughness
Direct quench from pot(d) Single quench and tempede) Double quench and temper(f)
(a) Carburized at 1700 “F(925 “C) for 8 h. quenched in agitated oil, tempered at 300 “F( IS0 “C). (b) Carhurized at I700 “F (925 “C) for 8 h, pot cooled reheated to 1525 “F (830 “0. quenched in agitated oil. tempered at 300 “F (150 “CJ. Good case and core properties. (c) Carburized at I700 “F (925 “C) for 8 h, pot cooled, reheated to IS25 “F (830°C). quenched in agitated oil. tempered at 300 “F ( I SO “C). Maximum refinement of case and core. (d) Carburized at I700 “F (925 “C) for 8 h. quenched in agitated oil, tempered at 450 “F(230”C).(e)Carburizedat 1700”F(925”C)for8h,potcooled,reheatedto lS2SoF(830”C).quenchedinagitatedoil,tempe~dat~S0”F(230”C).Goodcaseandcoreproperties. (f)Carburizedat 17OO”F(925 “0 for 8 h, pot cooled. reheated to I.525 “F(830”C). quenchedin agitatedoil. tempered iit lSO”F(230 “C). Maximum refinement ofcaseandcore. Source: Bethlehem Steel
Alloy Steels (1300 through 9700 Series) / 307
4120H,
4120RH
Chemical Composition. 4120H. AISI and UNS H41200: 0.18 IO 0.23 C. 0.90 to 1.20 Mn. 0.15 to 0.35 Si. O.-IO to 0.60 Cr. 0.13 to 0.20 MO. SAE4120~:0.18to0.23C.0.90to1.20Mn,0.15to0.35Si.0.~0to0.60 Cr. 0. I3 to 0.20 MO
Similar Steels (U.S. and/or Foreign). added to SAE J I268 and J I868 and to ASTM standard H-steel
Characteristics. its, but is carefully
8630
Both steels were recently A9l-I. There is no existing
The RH grade is made to narrower composition controlled to provide restricted hardenability.
steels are equivalent to 8620H and 862ORH in hardenability, but have higher manganese content. no nickel, slightly higher chromium, and slightly less molybdenum. Jn application. these steels are alternatives for
Recommended Hardening. Ion processes
limBoth
Heat Treating nitriding.
gas nitriding,
Practice and carbonitriding
are suitable
308 / Heat Treater’s
Guide
4120RH: Hardenability
Curves. Heat-treating
“C (1700 “F). Austenitiie:
Hardness Purposes .I distance, ‘/,#j in. 1 2 3 4 5 6 I 8 9 10 11 12 13 14 15 16 18 20 22 24 26 28 30 32
Hardness Purposes 1 distance, mm 1.5 3 5 7 ? I1 13 15 10 ?5 30 35 to 15 $0
925 “C (1700 “F)
Limits for Specification Hardness, HRC Madmum Minimum 47 45 41 38 34 31 29 28 26 25 24 23 23 22 22 21 20
42 39 35 30 26 24 22 21 20
.. . .
..
.
. . Limits for Specification
Hardness, HRC Maximum Minimum 41 45 41 36 32 29 28 26 23 21
. .. .
42 39 34 28 25 22 21 20 .
temperatures
recommended
by SAE. Normalize (for forged or rolled specimens
only): 925
Alloy Steels (1300 through
9700 Series) / 309
4130,413OH Chemical
Composition.
4130. AISI and UNS: 0.28 to 0.33 C. 0.40
toO.60~ln.0.lSto0.30Si.0.03SPn~a~.0.0~0Smax.0.80to
Recommended
to 0.25 MO. UNS HJ1300 and SAE/AISI J130H: 0.27 to 0.33 C. 0.30 to 0.70 hln. 0.035 P max. 0.010 S max. 0. I5 to 0.30 Si. 0.75 to I.20 Cr. 0. IS
Normalizing.
to 0.3
Annealing.
hlo
Similar Steels (U.S. and/or Foreign). 113O.l~NSG41300;AbIS 6350. 6356. 6360. 636 I. 636’. 6370. 637 I. 6373; ASTM A322. A33 I. A505. ASl3. ASl9, A6-lh: hlfL SPEC MLS-16971: SAE J-IO-I, J-112. 5770; (Ger.) DIN I .7118: (Fr.) AFNOR 25 CD -t(S); (Ital.) UNI 25 Crhlo 1.25 Crhlol KB: (Jap.) JIS SChl 2. SCCM I; (Swed.) SS)-) 3325; (U.K.) B.S. CDS I IO. 41308. UNS H-l 1300; ASThI A.304; SAE J-107: (Ger.) DIN I .72 18; (Fr.) AFNOR 25 CD -t(S); (Ital.) UNI 35 Crhlo -I. 25 Crhlo -I KB; (Jap.) JIS SCM 2. SCCrbl I; (Sned.) SSIJ 3335: (U.K.) B.S. CDS I IO
Heat to 900 “C ( I650 “FL Cool in air
For a predominateI> pearlitic structure. heat to 855 “C ( IS70 “F). cool fairly rapidly to 760 “C (I400 ‘F). then to 665 “C (1730 “F) at a rate not to exceed I8 “C (35 “F) per h; or heat to 85.5 “C ( I575 “F), cool rapidly to 675 “C ( I245 “F). and hold for -I h. For a predominately spheroidized structure. heat to 750 “C i I380 “F), cool from 750 “C (I 380 “F) to 665 “C (1230 “F) at a mte not to exceed 6 “C (IO “F) per h: cool ranidlv . - from 750 ‘C ( 1380 “F) to 675 “C ( I ?-I5 OF). and hold for 8 h
Hardening.
A medium-carbon alloy steel which can he oil quenched to attain a maximum as-quenched hardness of approximately 48 HRC. Its hardenahilitl is significantly higher than that of the carbon-molybdenum (40xX) grades. 3130H is produced in a number of product forms including tubing. -l I3OH has been used extensively for structures such as airframes that are fabricated from tubing. -1130H is ueldahlc. hut because of its fairlj high hardenahility. preheating and postheating must he used
l
Forging.
l
Austenittre
at 870 “C ( 1600 “FL and quench in oil
Reheat to the temperature
Recommended l l l l
Heat to 1230 “C (2245 OF) maximum. Do not forge after temperature of forging stock drops below approximateI) 870 “C (I 600 “F)
4130: Continuous Cooling Transformation
Practice
Tempering.
Characteristics.
tized at 850 “C (1560 “F)
Heat Treating
l.lOCr,O.lS
Diagram. Composition:
l
u hich itill
Processing
result in the required
hardness
Sequence
Forge Normalize Anneal Rough machine Austenitize and quench Temper Finish machine
0.30 C, 0.50 Mn. 0.020 P, 0.020 S, 0.25 Si, 1 .OOCr, 0.20 MO. Austeni-
310 / Heat Treater’s
Guide
4130: Isothermal Transformation
4130H:
Diagram. Composition:
0.33 C, 0.53 Mn, 0.90 Cr, 0.18 MO. Austenitized
End-Quench Hardenability
Dice from quenched surface ‘116 In. mm
Esrdness, ERC max min
Distance from queocbed surface ‘/la in. mm
Eardness, ERC max min
I 2 3
1.58 3.16 4.14
56 55 53
49 46 42
13 14 15
20.53 22.12 2370
34 34 33
24 23 23
4 5
6.32 7.90
51 49
38 34
16 18
25.28 28.44
33 32
23 22
6 7 8
9.48 11.06 12.64
41 44 42
31 29 27
20 22 24
31.60 34.76 31.92
32 32 31
21 20
9 IO
14.23 15.80
40 38
26 26
26 28
41.08 11.24
31 30
II 12
17.38 IS.%
36 35
25 25
30 32
47.40 SO.56
30 29
at 845 “C (1555 “F). Grain size:
Alloy
4130:
As-Quenched
Specimens
Hardness
mm
Surface
Eardnes, ARC l/r radius
Center
‘/z I 2 4
I3 25 51 I02
51 51 4-l 45.5
50 50 32 25
SO 44 31 24.5
round
Source: Bethlehem
9700 Series) / 311
4139: Cooling Curves. Steel tubing. 31.75 mm (1.25 in.) outside diameter by 1.651 mm (0.065 in.) wall
were quenched in water
in.
Si
Steels (1300 through
Steel
4130: Hardness vs Tempering Temperature. Normalized at 900
4130H: End-Quench Hardenability. 48 heats of 14835 contain-
“C (1650 “F). Quenched from 870 “C (1600 “F) in water and tempered at 56 “C (100 OF) intervals in 13.7 mm (0.540 in.) rounds. Source: Republic Steel
ing0.35to0.39C,0.65to1.10Mn,0.13Nimax,0.05Crmax,0.03 MO max and boron treated; compared with 4130H
312 / Heat Treater’s
Guide
Microstructures. (a) 2% nital. 500x. Normalized by austenitizing at 870 “C (1600 “F) and air cooling to room temperature. Ferrite (white areas) and lamellar pearlite (dark areas). Specimen shows slight banding. (b) 20/o nital. 750x. Hot rolled steel bar, 25.4 mm (1 in.) diam, annealed by austenitizing at 845 “C (1555 “F) and cooling slowly in the furnace. Coarse lamellar pearlite (dark areas) in a matrix of ferrite (white). (c) 2% nital, 750x. Hot rolled steel bar 25.4 mm (1 in.) diam. austenitized at 845 “C (1555 “F) for 1 h, cooled to 675 “C (1245 “F) and held for 2 h, and air cooled. Partly spheroidized pearlite (dark) in a matnx of ferrite (white). (d) 29b nital. 750x. Same as (c), except the time at 675 “C (1245 “F) was increased to 4 h. Structure essentially the same as (c), except the degree of spheroidization of the pearlite is greater. (e) 2% nital. 750x. Same as (c) and (d), except the time at 675 “C (1245 “F) was increased to 8 h. Structure is similar to those shown in (c) and (d), except the degree of spheroidization of the pearlite has increased further. (f) 2% nital, 750x. Same as (c), (d), and (e), except that the time at 675 “C (1245 “F) was increased to 16 h. The degree of spheroidization is greater than in (e). (g) 2% nital. 750x. Hot rolled steel bar, 25.4 mm (1 in.) diam, austenitized at 870 “C (1600 “F) for 1 h and water quenched. Untempered martensite. (h) 5% picric acid, 2 !/20/b HNO,, in ethanol; 11 000x. Same as (g), except an electron micrograph of a platinum-carbon-shadowed two-stage carbon replica. Untempered martensite. (j) Not polished, not etched: 8600x. Annealed. Replica electron fractograph. Note fatigue striations, resolved only at high magnification 4130:
Alloy Steels (1300 through
4130H: Hardenability Curves. Heat-treating (1650 “F). Austenitize:
870 “C (1600 “F)
iardness Limits for Specification Durposes distance, om .5
t 1 3 5 !O !5 IO I5 lo I5 i0
Hardness, HRC Maximum Minimum 56 55 53 51 48 44 41 39 34 33 33 32 31 31 30
49 46 40 36 32 28 26 25 24 23 22 20 .
iardness Limits for Specification Burposes 1distance,
46h.
IO 11 12 13 14 I5 16 18 !O !2 !4 !6 !8 10 52
Hardness. HRC hlaximum Minimum 56 55 53 51 49 47 44 42 40 38 36 35 34 34 33 33 32 32 32 31 31 30 30 29
49 46 42 38 34 31 29 27 26 26 25 25 24 24 23 23 22 21 20
temperatures
recommended
9700 Series) / 313
by SAE. Normalize (for forged or roiled specimens
only): 900 “C
314 / Heat Treater’s
Guide
4135,413SH Chemical
Composition.
Similar
In aerospace practice.
4135. AISI: 0.33 to 0.38 C. 0.70 to 0.90
Mn. 0.80 to 1.10 Cr. 0.035 P max. 0.040 S max. 0.15 to 0.25 MO. UNS: 0.33toO.38C.O.70too.90 Mn.0.035 Pmax.0.04OS max.0.15 to0.30Si. 0.80 to l.lOCr, 0.70 to 0.90 Mo.UNS H41350and SAE/AISI 41358: 0.32 to 0.38 C. 0.60 to 1.00 Mn. 0.15 to 0.35 Si, 0.75 to 1.20 Cr. 0. I5 to 0.25MO
Steels (U.S. and/or
Foreign). 4135. UNS ~41350; AMS ASTM A274. A355. A519; MlL SPEC MU-S-16974, MLS-18733; SAE J404.54 12.5770; (Ger.) DIN I .7220; (Fr.) AFNOR 35 CD 4.35 CD 4 TS; (Ital.) UNI 35 CrMo 4.35 CrMo 4 F, 34 CrMo 4 KB; (Jap.) JIS SCM I. SCCrM 3; (Swed.) SSla 2234; (U.K.) B.S. 708 A 37. 41358. UNSH41350; ASTM A304: SAE Jl268; (Ger.) DIN 1.7220; (Fr.) AFNOR 35 CD 4,35 CD 4 TS; (Ital.) UNI 35 CrMo 4. 35 CrMo 3 F, 34 CrMo 4 KB; (Jap.) JIS SCM I, SCCrM 3; (Swed.) SSld 2234; (U.K.) B.S. 708A 37
6365C. 6372C;
For a predominately pearlitic structure. heat to 855 “C (I 570 “F), cool fairly rapidly to 760 “C ( I300 “F). then to 665 “C ( I230 “F) at a rate not to exceed I9 “C (35 “F) per h: or heat to 855 “C (1570 “F). cool rapidly to 675 “C (I245 “F). and hold for 4 h. For a predominately spheroidized structure. heat to 750 “C ( I380 “F). cool from 750 “C (I 380 “F) to 665 “C (I 230 “F) at a rate not to exceed 6 “C ( IO OF) per h; or cool rapidly from 750 “C ( 1380 “F) to 675 “C ( 1245 “F), and hold for 8 h. Anneal at 845 “C (I 555 “F); cool to belou 540 “C ( IO00 “F) at a rate not to exceed I IO “C (200 “F) per h
Hardening. Austenitize at 870 “C (1600 “F), and quench in oil or polymer. Flame hardening, ion nitriding, gas niuiding, and carbonitriding are suitable processes. In aerospace practice. austenitize at 855 “C (1570 “F). Quench in oil or polymer Tempering.
Forging.
l
Forge Normalize
l
Armed
l
Rough machine Austenitize and quench Temper Finish machine
Heat to 1230 “C (2245 “F) maximum. Do not forge after of forging stock drops below approximately X70 “C ( I600 “F)
Recommended
Heat Treating
Practice
Reheat to the temperature which will result in the required hardness. ln aerospace practice. see table for suggested tempering temperatures per different tensile strengths. Quenchants include oil and polymers
Recommended l
l l
Normalizing.
Heat 10 900 “C ( I650 “F). Cool in air.
at 900 “C ( 1650 “F)
Annealing.
Characteristics. 4 l35H has generally the same characteristics as 4130H. except the higher mean carbon content results in a slightly higher as-quenched hardness, about 50 to 52 HRC for 4135H. ln addition. the higher mean manganese content of 3 I35H results in higher hardenahility. CornDare hardenabilitv data for 4130H with 4135H. Also, as the hardenability increases, the suitability for welding decreases. Forgeability of 4135H is very good temperature
normalize
l
Processing
Sequence
4135H: End-Quench Hardenability
Diitancefrom queocbed surface 916 in. mm
Eardness, ERC
max
min
Distance fern quenched surface ‘116in. mm
Ei3HllleSS,
ERC
max
min
I 2
1.58 3.16
58 58
51 50
13 1-I
20.54 22.1’
48 47
32 31
3 4 5 6 7 8 9 IO II II
4.74 6.32 7.90 9.48 II.06 12.64 14.22 15.80 17.38 18.%
57 56 56 55 54 53 52 51 SO 31
49 48 47 45 42 40 38 36 34 33
IS I6 I8 20 22 24 26 28 30 32
23.70 25.28 28.4-l 31.60 34.76 37.92 41.08 44.24 47.40 50.56
46 45 4-l 42 41 40 39 38 38 37
30 30 29 28 27 27 27 26 26 26
4135, 4135H: Hardness vs Tempering Temperature. Represents an average based on a fully quenched structure
Alloy Steels (1300 through
4135H: Hardenability Curves. Heat-treating (1600 “F). Austenitize:
Hardness Purposes I distance, mm 1.5 3 5 7 ?
11 13 15 20 25 30 35 $0 15 50
Hardness Purposes I distaace, $6 in. 1 2 3 1 5 5 7 B 9
10 11 12 13 14 15 6 8 :0 12 !4 :6 :8 IO I2
845 “C (1555 “F)
Limits for Specification Eardoess, HRC Masimum Minimum 58 58 57 56 56 55 53 52 49 45 43 41 40 39 37
51 50 49 48 46 42 39 37 32 30 28 27 27 26 26
Limits for Specification Hardness, ERC
Maximum
Minimum
58 58 57 56 56 55 54 53 52 51 50 49 48 47 46 45 44 42 41 40 39 38 38 37
51 50 49 48 47 45 42 40 38 36 34 33 32 31 30 30 29 28 27 27 27 26 26 26
temperatures
recommended
9700 Series) / 315
by SAE. Normalize (for forged or rolled specimens
only): 870 “C
316 / Heat Treater’s
4135: Suggested Practice)(a) 620-860 hlPa (W-125 ksi) 850 “C (1550°F)
Guide
Tempering
Temperatures
Tensile strength ranges 860-1035 hlPa 1035-1175 MPa 11751210 (IZS-1SOksi) (150-170hi) (170-180 675 “C (1250 “F)
(a) Quench in oil or polymer.
600 T (1125°F)
Source: AbfS 27.5911
(Aerospace
MPa ksi)
480 “C 1900 “F)
1240-1380 MPa (180-2OOksi) -I25 “C (800 “F)
4135: Suggested Tempering Temperatures Based on As-Quenched Hardness (Aerospace Practice) Tensile strength
range
860 IO 1035 hlPa I I25 to I50 ksl) 365 to I IO5 hlPa I I40 IO 160 ksl, 1035t01175hlPn (ISOto 170ksi) ll75tol3l0hlPa (170~~ 19Oksi) I240 to I380 hlPu (I80 to 200 ksi) Sourer: AhlS 2759/l
RC 47-49
As-Quenched Aardness RC 50-52
RC 53-55
550 “C (1025 “F) 5lO”C (950 ‘F) 170 ‘T 1875 OF) -12s ‘T t8OO”FI ml “C r750”F,
595 “C ~1100°F~ 550 “C (1025°F) SlO”C t9SO “F) 180 “C (900 “Fb 1.55 “C t85O”F)
650 “C t 12OOT) 595 “C (1100°F) 550 “C (1025 “F) -5’5 -_ “C (975 “F) 19s “C (925 “I=)
316 / Heat Treater’s
Guide
4137,4137H Chemical
Composition.
4137. AISI and UNS: 0.3s LO0.40 C. 0.70
to0.90Mn.0.15to0.30Si.0.80to1.10Cr.0.035Pmax.0.010Smax.0.15 to 0.25 MO. UNS H41370 and SAE/AISI J137I-I: 0.34 to 0.31 C. 0.60 to 1.00 Mn. 0. IS to 0.35 Si. 0.75 to 1.20 Cr. 0.15 to 0.25 MO
Similar
Steels (U.S. and/or Foreign). 5137. LINS G41370: ASTM A322, A33 I, AS05, A5 19. AS17; SAE J-IO4 Jll2, J770; (Ger.) DIN I .7225; (Fr.) AFNOR 40 CD 4.42 CD 4; (Id.) UNI G -IO CrMo 1.38 C&lo 4 KB. 40 CrMo 1; (Jap.) JIS SCM -I H. SChl3: (Swed.) SS1.t 2344; (U.K.) B.S. 708 A 32.708 M 10.709 M 10.1137H. LJNS H41370; ASTM ,430-I; SAEJI268;(Ger.)DfN 1.722S;(Fr.)AFNOR40CDJ.42CD-l;(Ital.)LJNl G 10 C&lo 4.40 CrMo 4. 38 CrMo 4 KB; fJap.) JIS SCM 4 H. SCM 4; (Swed.) SS1-t 2244; (U.K.) B.S. 708 A 42.708 A 40.709 A 10 Characteristics. A typical medium-carbon. moderately high hardenability steel. Often referred to as a shaft steel, -I I37H is frequently used for a variety of shaft applications in the quenched and tempered condition. Depending upon the precise carbon content. the as-quenched hardness of fully hardened 4137H is generally about 52 HRC or slightly higher. usualI> a little higher than 413SH. but not as high as for ll40H. The hardenability pattern is essentially the same for 3137H as shown for 3135H: the only difference is that the band is moved upward for 4137H because of the higher carbon content. Forgeability of1137H is very good, but machinability is only fair and welding. although possible. is seldom recommended Forging. Heat to 1230 “C (22-U “F). Do not forge after temperature forging stock drops below approximately 870 “C ( I600 “F)
Recommended Normalizing.
Heat Treating
Practice
Heat to 870 “C f I600 “Fj. Cool in air
For a predominately pearlitic structure. heat to 835 “C ( I555 “F). cool fairly rapidly to 755 “C ( I390 “Fj. then cool from 755 “C ( I390 “F) to 665 “C ( 1230 “F) at a rate not to exceed I1 “C (25 “F) per h; or heat to 845 “C (I 555 “F). cool rapidly to 675 “C ( IX5 “F). and hold for 5 h. For a predominately spheroidized structure. heat to 750 “C ( 1380 “F), cool to 665 “C (I230 “F) at a rate not to exceed 6 “C (IO “F) per h; or heat to 750 “C ( I380 “F), cool fairly rapidly to 675 “C ( I245 “F). and hold for 9 h
Hardening.
Austenitize at 855 “C (I570 “F), and quench in oil. Carbonisalt bath and gas nitriding, and ion nitriding are suitable processes
Tempering.
Recommended l l l l l l l l l
Processing
Sequence
Forge Normalize Anneal Rough machine Austenitize Quench Temper Finish machine Nitride (optional)
of
Annealing.
triding.
Nitriding. If nitriding is considered. the steel must be treated (hardened and tempered), and nitriding must be done on finished parts because any finishing operation will remove the most useful portion of the case. First. use a typical processing cycle consisting of: rough machining, austenitizing at 845 “C I I555 “FI. oil quenching. tempering at 620 “C (I I50 “F). and finish machining. Then, nitride in ammonia gas at 525 “C (975 “F) for 21 h. using an ammonia dissociation of 30%: or nitride at 525 “C (975 “F) for 5 h with an ammonia dissociation of 25%. then at 565 “C ( 1050 “F) for 20 h nith an ammonia dissociation of 75 to 805. Certain proprietary salt bath nitriding processes are also applicable for surface hardening
Reheat after quenching to the temperature shown by the hardness-tempering temperature curve to obtain the required hardness for these specific steels
4137, 4137H: sents an average
Hardness based
vs Tempering
Temperature.
on a fully quenched
structure
Repre-
Alloy
Steels (1300 through
9700 Series) / 317
4137H: End-Quench Hardenability Distance from quenched surface ‘&jin. mm I 2 3 -I 5 6 7 8 9 IO II I’
1.58 3.16
Eardness, ERC mar min
6.31 7.90 9.4 II.06 12.64
59 59 58 58 57 57 56 55
14.22
55
I5 80 17.38 18.96
54 53 52
1.71
52 51 SO 49 49 18 -Is 1.3 -IO 39 37 36
Distance from quenched surface ‘&in. mm 13 I-1 IS 16 18 10 x! 2-l 26 28 30 32
4137: Continuous Cooling Transformation tized at 860 “C (1580 “F)
20.5-i 22.12 23.70 2528 28.4-I 31 60 31.76 37.92 -I I Ax3 44.24 47.40 SO.56
Rardness. ARC mas min 51 50 49 48 46 45 44 43 4’ -I1 41 II
35 34 31 31 3’ 31 30 30 30 29 ‘9 29
Diagram. Composition:
0.36 C, 0.80 Mn, 0.020 P, 0.020 S, 0.25 Si. 1 .OOCr, 0.20 MO. Austeni-
318 / Heat Treater’s
4137H:
Hardenability
(1600 “F). Austenitize:
Hardness Purposes J distance, mm 1.5 3 5 7 3 I1 13 15 20 25 30 35 $0 15 50
Hardness Purposes I distance, 1/16in. I 2 3 1 5 5 7 3 3 IO I1 12 13 14 I5 16 I8 20 !2 !4 !6 !8 !O 52
Guide
Curves. Heat-treating 845 “C (1555 “F)
Limits for Specification Eardness, ERC MaximlUll Minimum 59 59 58 58 57 56 55 55 52 48 46 44 43 42 41
52 51 50 49 48 45 42 39 35 33 31 30 29 29 29
Limits for Specification Eardoess. ARC Maximum Minimum 59 59 58 58 57 57 56 55 55 54 53 52 51 50 49 48 46 45 44 43 42 42 41 41
52 51 50 49 49 48 45 43 40 39 37 36 35 34 33 33 32 31 30 30 30 29 29 29
temperatures
recommended
by SAE. Normalize (for forged or rolled specimens
only): 870 “C
Alloy Steel / 319
4140,414OH Chemical Composition. 4140. AISI and UNS: 0.38 to 0.43 C, 0.75 to1.00Mn,0.035Pmax,0.040Smax,0.15to0.30Si,0.80to1.10Cr,0.15 to 0.25 MO. 414OH.AISIandUNS: 0.37 to 0.44 C, 0.65 to l.lOMn, 0.035 Pmax.0.040 S max,0.15 too.30 Si.O.75 to 1.2OCr,O.15to 0.25 MO Similar Steels (U.S. and/or Foreign). 4140. UNS ~41400;
AMS
6381.6382,6390,6395; ASTM A322, A331, A505, A519, A547, A646; MlL SPEC M&S-16974; SAE J404, J412.5770; (Ger.) DIN 1.7225; f,Fr.) AFNOR 40 CD 4.42 CD 4; (Ital.) UN1 40 CrMo 4, G 40 CrMo 4,38 CrMo 4 KB; (Jap.)JIS SCM 4 H, SCM 4; (Swed.) SSt4 2244; (U.K.) B.S. 708 A 42,708 M 40,709 M 40.4140H. UNS H41400; ASTM A304; SAE 5407; (Ger.)DIN 1.7225;(Fr.) AFNOR 40 CD 4,42 CD 4; (Ital.) UN1 G 40 CrMo 4,40 CrMo 4,38 CrMo 4 KB; (Jap.) JIS SCM 4 H, SCM 4; (Swed.) SS14 2244; (U.K.) B.S. 708 A 42,708 M 40,709 M 40
Characteristics.
Among the most widely used medium-carbon alloy steels.Relatively inexpensive considering the relatively high hardenability 4140H offers. Fully hardened 4140H ranges from about 54 to 59 HRC, depending upon the exact carbon content. Forgeability is very good, but machinability is only fair and weldability is poor, becauseof susceptibility to weld cracking
Tempering. Reheatafter quenching to obtain the required hardness Nitriding. 4140H respondsto the ammonia gasnitriding process,resulting in a thin, file hard case, the outer portion of which is composedof epsilon nitride. This constituent not only provides an abrasion-resistant surface,but also increasesfatigue strength of componentssuch as shaftsby as much as 30%. However, if nitriding is considered, the steel must be pretreated(hardenedand tempered),and nitriding must be done on finished parts becauseany finishing operation will remove the most useful portion of the case.A typical processingcycle that includes nitridmg is: l l l l l l
Rough machine Austenitize at 845 “C (1555 “F) Oil quench Temper at 620 “C (1150 “F) Finish machine Nitride at 525 “C (975 “F) for 24 h, using an ammonia dissociation of 30%; or nitride at 525 “C (975 “F) for 5 h with an ammoniadissociation of 25%. then at 565 “C (1050 “F) for 20 h with an ammoniadissociation of 75 to 80%
Forging. Heat to 1230 “C (2250 “F). Do not forge after temperatureof forging stock drops below approximately 870 “C (1600 “F)
Certainproprietarysalt bath nitriding processesarealso applicablefor surface hardeningof414OH
Recommended
Recommended
Heat Treating
Practice
Normalizing. Heat to 870 “C (1600 “F). Cool in air Annealing. For a predominately pearlitic structure, heatto 845 “C (1555 “F), cool fairly rapidly to 755 “C (1390 “F), then cool from 755 “C (1390 “F) to 665 “C (1230 “F), at a rate not to exceed 14 ‘C (25 “F) per h; or heat to 845 “C (1555 “F), cool rapidly to 675 “C (1245 “F), and hold for 5 h. For a predominately spheroidized structure, heat to 750 “C (1380 “F), cool to 665 “C (1230 “F) at a rate not to exceed 6 “C (10 “F) per h; or heat to 750 “C (1380 “F), cool fairly rapidly to 675 “C (1245 “F), and hold for 9 h
l l l l l l l l l
Processing
Sequence
Forge Normalize Anneal Rough machine Austenitize Quench Temper Finish machine Nitride (optional)
Hardening. Austenitize at 855 “C (1570 “F), and quench in oil 1140: Isothermal Transformation 7 to 8
Diagram. Composition:
0.37 C, 0.77 Mn, 0.98 Cr, 0.21 MO. Austenitized
at 845 “C (1555 “F) Grain size:
320 / Heat Treater’s
Guide
4140H: End-Quench Hardenability Distance from quenched surface
&jh. 1 2 3 4 5 6 7 8 9 10 11 12
mm 1.58 3.16 4.14 6.32 7.90 9.48 11.06 12.64 14.22 15.80 17.38 18.96
Hardness, ARC max min 60 60 60 59 59 58 58 57 57 56 56 55
53 53 52 51 51 50 48 41 44 42 40 39
4140: Cooling Transformation
Distance from quenched surface
‘/x6h
mm
13 14 15 16 18 20 22 24 26 28 30 32
20.54 22.12 23.10 25.28 28.44 31.60 34.16 31.92 41.08 44.24 41.40 50.56
Hardness, ARC max min 55 54 54 53 52 51 49 48 41 46 45 44
38 37 36 35 34 33 33 32 32 31 31 30
Diagram. Composition: 0.44 C, 1.04 Mn, 0.29 Si, 1 .13 Cr, 0.15 MO. Austenitized size: 9. AC,, 795 “C (1460 “F); AC,, 750 “C (1380 “F). A: austenite, F: ferrite, P: pearlite, B: bainite, M: martensite.
at 845 “C (1555 “F). Grain Source: Bethlehem Steel
Alloy Steel / 321
4140:
Effect of Microstructure
on Tool Life
Feed was 0.010 in./rev (0.25 mm/rev) for all specimens;
depth of cut was 0.100 in. (2.5 mm). Microstructure
Steel condition
Hardness, HB
Pearlite
Ferrite
192 180 300
90 65
10 35
Normalized Annealed Quenched tempered
4140:
As-Quenched
Specimens
‘h 1 2 4
Tempered martensite
Hardness
13 25 51 102
ft/miu
mm/s
300 360 300
1520 1830 1520
4140: Hardness vs Tempering Temperature. Normalized at 870
quenched in oil
mm
cutting speed
100
Size round in.
constituent, %
“C (1600 “F). Quenched from 845 “C (1555 “F) in oil and tempered in 56 “C (100 “F) intervals in 13.716 mm (0.540 in.) rounds. Tested in 12.827 mm (0.505 in.) rounds. Source: Republic Steel
Surface
Hardness, HRC t/z radius
Center
57 55 49 36
56 55 43 34.5
55 50 38 34
Source: Bethlehem Steel
4140: Effect of Mass. Composition: 0.38 to 0.43 C, 0.75 to 1 .OO Mn, 0.040 P max, 0.040 S max, 0.20 to 0.35 Si, 0.80 to 1.10 Cr, 0.15 to 0.25 MO. Approximate critical points: AC,, 730 “C (1350 “F); AC,, 805°C (1480°F); Ar,, 745 “C (1370°F); Ar,, 680 “C (1255 “F). Recommended thermal treatment: forge at 1205 “C (2200 “F) maximum, anneal at 815 to 870 “C (1500 to 1600 “F) for a maximum hardness of 197 HB, normalize at 845 to 900 “C (1555 to 1650 “F) for an approximate hardness of 311 HB; quench from 830 to 855 “C (1525 to 1570 “F) in oil. Test specimens were normalized at 870 “C (1600 “F) in over-sized rounds, quenched from 845 “C (1555 “F) in oil in sizes shown, tempered at 540 “C (1000 “F), tested on 12.827 mm (0.505 in.) rounds. Tests from 38.1 mm (1.5 in.) diam bars and over are taken at half radius position. Source: Republic Steel
4140: Gas Nitriding. Oil quenched from 845 “C (1555 “F), tempered at 595 “C (1105 “F), and nitrided at 550 “C (1020 “F) I I
4140: Depth of Hardness.
31.75 mm (1.25 in.) diam bars,
through hardened by induction
0
20 Duration
40 of nitriding,
60 hr
60
322 / Heat Treater’s
Guide
4140: Effect of Mass. Composition: 0.38 to 0.43 C, 0.75 to 1 .OO Mn, 0.040 P max, 0.040 S max, 0.20 to 0.35 Si, 0.80 to 1.10 Cr, 0.15 to 0.25 MO. Approximate critical points: AC,, 730 “C (1350 “F); AC,, 805 “C (1480°F); Ar,, 745 “C (1370 “F); Ar,, 680 “C (1255 “F). Recommended thermal treatment: forge at 1205 “C (2200 “F) maximum, anneal at 815 to 870 “C (1500 to 1600 “F) for a maximum hardness of 197 HB, normalize at 845 to 900 “C (1555 to 1650 “F) for an approximate hardness of 311 HB; quench from 830 to 855 “C (1525 to 1570 “F) in oil. Test specimens were normalized at 870 “C (1600 “F) in over-sized rounds, quenched from 845 “C (1555 “F) in sizes shown, tempered at 650 “C (1200 “F), tested on 12.827 mm (0.505 in.) rounds. Tests from 38.1 mm (1.5 in.) diam bars and over are taken at half radius position. Source: Republic Steel
4140: Variations in Hardness after Production Tempering. (a) 76.2 mm (3 in.) diam valve bonnets. Steel from one mill heat. Parts heated at 870 “C (1600 “F), oil quenched, and tempered at 605 “C (1125 “F) to a hardness of 255 to 302 HB. (b) Valve segments, 12.7 to 25.4 mm (0.5 to 1 in.) section thickness. Steel from one mill heat. Parts heated at 870 “C (1600 “F), oil quenched, and tempered at 580 “C (1075 “F) to a hardness of 321 to 363 HB
4140: Depth of Case vs Duration of Nitriding. Double stage nibided at 525 “C (975 “F). Numbers indicate hours of nitriding at 15 to 25% dissociation. Remainder of cycle at 83 to 85% dissociation
4140: Effect of Microstructure
on Tool Life
Heat Treater’s
Guide: Practices
and Procedures
for Irons and Steels
Copyright@ ASM International@ 1995
Alloy Steel I323
4140: Gas Nitriding. (a) 7 h, 2 suppliers, 20 to 30% dissociation; dissociation; (d) 40 h, 5 heats, 25 to 30% dissociation; to 30% dissociation; (h) 50 h, 20 to 30% dissociation. core hardness
(b) 9 h, 2 heats, 25 to 30% dissociation; (c) 24 h, 2 suppliers, 20 to 30% (e) 90 h, 9 heats, 25 to 35% dissociation; (f) 25 h, 20 to 30% dissociation; (g) 35 h, 20 For (f), (g), (h), 1: 21 to 23 HRC; 2: 26 to 28 HRC; 3: 33 to 35 HRC; 4: 36 to 37 HRC
324 / Heat Treater’s
4140: Microstructures.
Guide
(a) 2% nital, 825x. Resulfurized forging normalized by austenitizing at 900 “C (1650 “F) Ii2 h. air cooling; annealed by heating at 815 “C (1500 “F) 1 h. furnace cooling to 540 “C (1000 “F), air cooling. Blocky ferrite and fine-to-coarse lamellar pearlite. Black dots are sulfide. (b) Nital, 500x. 25.4 mm (1 in.) diam. austenitized at 845 “C (1555 “F) 1 h. cooled to 650 “C (1200 “F). and held 1 h for isothermal transformation, then aircooled to room temperature. White areas, ferrite; gray and black areas, pearlite with fine and coarse lamellar spacing. (c) 2% nital, 500x. Hot rolled steel round bar. 25.4 mm (1 in.) diam, austenitized at 845 “C (1555 “F) for 1 h and water quenched. Fine, homogeneous. untempered martensite. Tempering at 150 “C (300 “F) would result in a darker etching structure. (d) 2% nital, 500x. Same as (c), except the steel was quenched in oil rather than water, resulting in the presence of bainite (black constituent) along with the martensite (light). (e) 2% nital, 750x. Steel bar austenitized at 845 “C (1555 “F). oil quenched to 66 “C (150 “F), and tempered 2 h at 620 “C (1150 “F). Martensite-ferrite-carbide aggregate. (f) As polished (not etched), 200x. Oxide Inclusions (stringers) in a steel bar, 25.4 mm (1 in.) diam. Stringers parallel to the direction of rolling on the as-polished surface of the bar. (g) Not polished, not etched, 8600x. Replica electron fractograph showing the dimpled structure typical of the overstress mode of failure. (h) 2% nital, 400x. Oil quenched from 845 “C (1555 “F), tempered for 2 h at 620 “C (1150 “F), surface activated in manganese phosphate, gas nitrided for 24 h at 525 “C (975 “F), 20 to 30% dissociation. 0.0050 to 0.0076 mm (0.0002 to 0.0003 in.) white surface layer Fe,N, iron nitride, and tempered martensite. (j) 2% nital. 400x. Same steel and prenitriding conditions as (h). except double stage gas nitrided: 5 h at 525 “C (975 “F), 20 to 30% dissociation: 20 h at 565 “C (1050 “F), 75 to 80% dissociation. High second-stage dissociation caused absence of white layer. Diffused nitride layer and a matnx of tempered martensite
Alloy Steel I325
4140H: Hardenability
Curves. Heat-treating temperatures 845 “C (1555 “F) -
(1600 “F). Austenitizk
Hardness purposes
I
limits for specification
I
I distsnce, mm
I
1.5
1 4 ; !
a
I1 13 II.5 2!O : !.5 )O )5 L10 L15 I I
io
z
I I
Hardness purposes I distance, II,l(i”.
. I
I 2 3 1 5 f5 7 I3 ,3 10 11 12 13 14 15 16 18 !O ,2 24 26 i ‘8 30 32
Hardness, HRC hlaximum hfiuimum 60 60 60 59 59 58 51 51 5.5 53 51 49 48 46 45
53 52 52 51 50 48 46 43 38 35 33 32 32 31 30
limits for specification Hardness, HRC Maximum hfinimum
60 60 60 59 59 58 58 51 57 56 56 55 55 54 54 53 52 51 49 48 47 46 45 44
53 53 52 51 51 50 48 47 44 42 40 39 38 37 36 35 34 33 33 32 32 31 31 30
recommended
by SAE. Normalize (for forged or rolled specimens
only): 870 “C
1
326 / Heat Treater’s
Guide
4142,4142H Chemical Composition. 4142. AISI and UN.% 0.40 to 0.45 C, 0.75 to1.00Mn,0.035Pmax,0.040Smax.0.15to0.30Si.0.80to1.10Cr.0.15 to 0.25 MO. UNS 841420 and SAE/AISI 4142H: 0.39 to 0.46 C, 0.65 to I. IO Mn. 0. I5 to 0.35 Si, 0.75 to 1.20 Cr. 0.15 to 0.35 MO
Tempering. required
Reheat after quenching hardness
to the temperature
to obtain
the
Steels (U.S. and/or Foreign). 4142. UNS G41420; ASTM A322. A33 I. A505. A5 19, A 547; SAE 5404.5412. J770.41428.
Nitriding. If nitriding is considered. the steel must be pretreated (hardened and tempered), and nitriding must be done on finished parts because any finishing operation will remove the most useful portion of the case. A typical processing cycle that includes nitriding is
UNS H41420; ASTM CrMo 4
l
Similar
A304; SAE J 1268: (Ger.) DfN I .7223; (Ital.) UNI 38
Characteristics. A slightly higher carbon version of 4140H. Characteristics are essentially the same as those described for 4140H. Depending on the precise carbon content within the allowable range, as-quenched hardness of fully hardened 4142H should be at least 54 HRC and may be as high as 60 HRC. 4142H is also a high hardenability steel. Can be readily forged, but as carbon increases, the susceptibility to cracking in heat treating or welding also increases, while machinability decreases Forging.
Heat to 1230 “C (2250 “F). Do not forge after temperature forging stock drops below approximately 870 “C (I600 “F)
Recommended Normalizing.
Heat Treating
l l l l l
of
Practice
Heat to 870 “C (1600 “F). Cool in air
Certain proprietaty hardening
For a predominately pearlitic structure. heat to 845 “C ( 1555 “F), cool fairly rapidly to 755 “C ( I390 “F). then cool from 755 “C ( I390 “F) to 665 “C ( I230 “F) at a rate not to exceed I4 “C (25 “F) per h; or heat to 845 “C (I 555 “F). cool rapidly to 675 “C ( I245 “F). and hold for 5 h. For a predominately spheroidized structure, heat to 750 “C (I 380 “F), cool to 665 “C ( 1230 “F) at a rate not to exceed 6 “C (IO “F) per h; or heat to 750 “C (I380 “F’), cool fairly rapidly to 675 “C (I 245 “F), and hold for 9 h Austenitize at 855 “C (I570 OF). and quench in oil. Flame hardening, ion nitriding, gas nitriding, and carbonitriding are suitable processes
salt bath nitriding
Recommended l
Annealing.
Hardening.
Rough machine Austenitize at 845 “C (1555 “F) Oil quench Temper at 620 “C ( I I50 “F) Finish machine Nitride at 525 “C (975 “F) for 24 h. using an ammonia dissociation of 30% or nitride at 525 “C (975 “F) for 5 h with an ammonia dissociation of 25%. then at 565 “C (1050 “F) for 20 h with an ammonia dissociation of 75 to 80%
l l l l l l l l
processes are also applicable for surface
Processing
Sequence
Forge Normalize Anneal Rough machine Austenitize Quench Temper Finish machine Nitride (optional)
4142: Increase in Lead Change with Depth of Nitrided Case. 13-tooth five-pitch helical pinion gear, hardened and tempered at 565 “C (1050 “F)and nitrided in two stages at 525 “C (975 “F) using ammonia dissociation rates of 15 to 25% for the first stage and 63 to 65% for the second stage
4142, 4142H: Hardness vs Tempering Temperature. sents an average based on a fully quenched structure
Repre-
Alloy Steel / 327
4142H: Continuous Austenitized
Cooling Transformation
Diagram. Composition:
0.42 C, 0.85 Mn, 0.020 P, 0.020 S, 0.25 Si, 1 .15 Cr, 0.20 MO.
at 880 “C (1580 “F)
4142H: End-Quench Hardenability Distance born quenched surface ‘/lb in. mm I -l ; -I 5 6 7 8 9 IO II I2
Eardness, ERC max min
I x3
62
5.5
4.73 3.16 6.32 7.90 9.18 Il.06 12.64 11.22 IS.80 17.38 18.96
62 61 61 61 60 60 60 59 59 58
!bl 55 53 53 52 51 50 49 47 46 4.4
4142: isothermal Transformation Distance from quenched surface &in. mm I3 I-l IS 16 18 20 22 24 26 28 30 32
20.51 22.12 23.70 25 28 28.-M 31.60 34.76 37.92 11.08 44.24 47.40 SO.S6
Diagram. Composition: 0.42 C. 0.89 Mn, 0.018 P, 0.028 S, 0.23 Si, 0.05 Ni, 0.94 Cr, 0.18 MO, 0.025 Al. 0: austenitized at 870 “C (1800 “F); 0: austenitized at 980 “C (1795 “F); A: austenitized at 1095 “C (2005 “F)
Eardoess. ERC min max 58 57 57 56 55 54 53 53 52 51 51 so
42 41 -+o 39 37 36 35 34 3-I 3-l 33 33
I
328 / Heat Treater’s
Guide
4142H: Hardenability (1600 “F). Austenitize:
Hardness purposes J distuuce, mm
Curves. Heat-treating 845 “C (1550 “F)
limits for specification Rardness, Maximum
ARC hlinimum
I .5 3 5 7 Y II I3 IS 20 2s
67 62 62 62 61 61 60 60 58 56
55 s-l s-l 53 52 51 -19 -la 13 BY
30 35
55 53
36 3s
40 15 so
52 51 SO
3-l 33 33
Hardness purposes I distauce, !/,6 in. I , 1 5 1 s ) IO II I2 13 I-1 IS 16 18 !O !2 !-I !6 !8 10 12
limits for specification Eat-does, Maximum 62 62 62 61 61 61 60 60 60 59 99 58 58 57 57 56 55 51 53 53 92 51 Sl 50
q RC Minimum 55 55 51 53 53 52 51 50 -19 -17 -I6 -l-l 12 -II 40 39 37 36 35 31 34 3-l 33 33
temperatures
recommended
by SAE. Normalize (for forged or rolled specimens
only): 870 “C
Alloy
4145,4145H,
Steel I329
4145RH
Chemical
Composition. 4145. AISI and CJNS: O.-l3 to 0.18 C. 0.75 to l.00hln.0.03SPmax.0.010Sniax.0.1Sto0.30Si.0.80toI.IOCr.0.lS to 0.3 MO. UNS H41450 and SAE/AISI 4145H: 0.42 to 0.49 C. 0.65 to I.10 Mn. 0.15 to 0.35 Si. 0.75 to I.20 Cr. 0.15 to 0.1-S hlo. SAEJIJSRH: O.-l3 to 0.48 C. 0.75 to 1.00 Mt. 0.80 to I. IO Cr. 0. I5 to 0.35 hlo Similar Steels (U.S. and/or Foreign). 41~5. 11~s G11150: ASThl A322 A33l. AS05. ASl9: hllL SPEC hIIL-S-16974; SAE J-104. J-112. J770.4145H. 1JNS H1I4SO; ASTM A3O-l. A9l-l: SAE 51’68. Jl868 Characteristics.
4145H. along with 1147H and -1lSOH. is commonly known tts a high-strength steel. All are capable ofbetn~g heat treated to high strengths. As-quenched -I l4SH M ill have hardness values ranging generally from approximately 55 to 62 HRC. In hardenability. 4l-tSH ranks as one of the highest of the AISI alloy steels. ForSeability is good. but because of high carbon content and high hnrdenahility. restricted cooling rate from the ftnish forging temperature is generally recommended. This can he accomplished hy cooling in a furnace or by co\ering with on insulating mnterial. Rapid cooling from the forginp temperature can result in cracking, especially for ForSings of complex contigurntton. hlachinahility is penerally regarded as poor. although 414SH is machined try all of the conventional processes. Strongly susceptible to \\eld cracking, and the entire \\elding process must be closely controlled. Often \selded usmg more sophisttcated processes such as plasma orc and electron beam. partly because of the applications for which it is most often used
Recommended Normalizing.
Heat to I220 “C (2225 “F). Do not forge after temperature of forging stock drops below approxmlately 870 ‘C t 1600 “Fj. Slow coolinp is recommended
Practice
Heat to 870 “C t 1600 “F). Cool in air
Annealing.
For a prsdominstely pcnrlitic structure. heat to 830 “C ( IS25 “Fj. cool fairly rapidly to 7-tS “C i 1370 “Fj. then to 670 “C ( I?-tO “Fj at a rate not to exceed 8 “C t IS W per h: or heat to 830 “C (IS25 “Pj. cool rapidly to 675 C t l2-lS “F). and hold for 6 h. For a predominately ferritic and spheroidired carhide structure. heat to 750 “C (I 380 ‘F’j. cool to 670 “C t 1240 “Fj at a rote not to esceed 6 ‘C t IO “Fj per h; or cool fairly rapidly from 750 “C t I380 “Fj to 660 “C t I230 OF). and hold for IO h
Hardening. Heat to 845 “C t IS55 “Fj, and quench in oil or polymer. Flame hardening. ion nitriding. gas nitridinp. and carbonitriding are suitable processes Tempering.
After quenching, reheat immediately to the tempering perature that will provide the required strength and/or hardness
Recommended l l l l
Forging.
Heat Treating
l l l
Processing
tem-
Sequence
Forge Normalize Anneal Rough machine Austenitire and quench Temper Finish mnchins
4145H: End-Quench Hardenability Distance from quenched surface &in. mm
Hardness, HRC mar min
Distance from quenched su tface l/l6 in. mm
Hardness, q RC max min
I
I..58
63
56
I?
‘0 5-I
59
-Lb
2 3 4 z
3.16 4.74 6.32 9.18 7.90
63 62 62 61 62
55 55 5-l 53
I-l IS I6 ‘018
22.12 23.70 3.18 3 I .60 28.4-I
59 58 S8 57
-I5 4.1 12 10 38
7 8
II 06 12.6-l
61 61
51 52
21 11
34.76 37.9’
Sh 55
37 36
9 IO
14.22
IS.80
60 h0
51 SO
26 28
-11.08
55 55
35
II I2
17.38 18.96
60 59
49 18
30 32
-17.10 50.56
5s 54
3-1 3-l
44.2-I
35
4145, 4145H: Hardness vs Tempering Temperature. sents an average
based
on a fully quenched
structure
Repre-
330 / Heat Treater’s
Guide
4145H: Hardenability (1600 “F). Austenitize:
Hardness purposes J distance, mm 1.5 3 5 7 ? 11 13 15 20 25 30 35 40 15 50
Hardness purposes I distance, Y,6 ill.
1 I , , I 1 I 0 1 2 3 4 5 6 8 10 12 14 16 18 i0 i2
Curves. Heat-treating 845 “C (1555 “F)
limits for specification Ehrdness, ERC llleximum Minimum 63 63 63 62 62 61 61 60 59 58 51 56 55 55 55
limits for
56 55 55 54 53 52 51 50 47 42 39 31 35 34 34
specification
Hardness, HRC Maximum Minimum 63 63 62 62 62 61 61 61 60 60 60 59 59 59 58 58 51 57 56 55 55 55 55 54
56 55 55 54 53 53 52 52 51 50 49 48 46 45 43 42 40 38 31 36 35 35 34 34
temperatures
recommended
by SAE. Normalize (for forged or rolled specimens
only): 870 “C
Alloy Steel / 331
4145RH: Hardenability Curves. Heat-treating “C (1600 “F). Austenitize: 845 “C (1555 “F)
Hardness purposes J distance, ‘/,6 in. I 2 3 4 5 6
1 8 9 IO II I? I3 I-l
IS 16 I8 20 22 24 26 28 30 32
Hardness purposes 1 distance,
mm IS 3 5
limits for specification Hardness, HRC hfaximum hfiuimum 62 62 61 61 60 60 59 59 58 58 58 57 51 56 56 55 54 53 52
57 51 56 56 55 55 5-l 53 52 52
51 SO 49 48 41 46 4-I 43 42
51
40
51 SO SO 49
40 39 38
31
limits for specification Eardness, HRC hlaximum Minimum
7 3 II I3
62 62 61 61 60 59 59
I5 10
58 51
Pi 30 ss lo 1s 50
55 5-I 52 Sl SO 49
51 51 56 56 55 s-i 53
52 19 -16 44 42 -IO 39
31
temperatures
recommended
by SAE. Normalize
(for forged or rolled specimens
only): 870
332 / Heat Treater’s
Guide
4147,4147H Chemical
COITIpOSitiOn. 4147. AISI and UNS: 0.45 to 0.50 C. 0.75 to 1.00 Mn.0.035 Pmax, O.O-lOS niax.0. I5 to 0.30 Si.O.80 to l.lOCr.0. IS to 0.25 MO. UNS H41470 and SAE/AISI 4147H: 0.U to 0.5 I C. 0.65 to I.10 Mn. 0.15 to 0.35 Si. 0.75 to 1.20 Cr. 0.15 to 0.25 Mo
Similar
Steels (U.S. and/or
Foreign).
4147.
UNS
~31470;
ASTM A322, A331, AS05. A519; WE J-W, Ul?, 5770: tGer.) DIN 1.7228; (Jap.) JIS SCM 5 H. SCM 5.4147H. UNS H11170: ASTM A30-I: SAE J 1268: (Ger.) DIN I .7228: (Jap.) JIS SCM 5 H. SCM 5
Characteristics.
The characteristics are much the same as those outlined for 111SH. Because of increased carbon content. the maximum as-quenched hardness is slightly higher. approximately 56 to 63 HRC. depending on the precise carbon content. Hardenability is high. and the band shows about the same pattern as that for 313SH. except for a shift slightly upward. Susceptibility to craching because of rapid cooling after forging. welding. or heat treating is greater than that for 111SH because of the higher carbon content
Annealing. For a predominately pearlitic structure. heat to 830 “C (I 52s OF). cool fairly rapidly to 745 “C ( I370 “FJ, then to 670 “C ( I240 “F) at a rate not to exceed 8 “C ( IS “F) per h: or heat to 830 “C ( IS25 “F), cool rapidly to 675 “C t 1245 “F). and hold for 6 h. For a predominately ferritic and spheroidized carbide structure, heat to 750 “C ( I380 “F), cool to 670 “C t 12-10 “F) at a rate not to exceed 6 “C ( IO “F) per h; or cool fairly rapidly from 750 “C ( I380 “F) to 660 ‘C t I220 “F). and hold for IO h Hardening. ing. ion &riding,
Tempering. perature that !iill
Heat to 1220 “C (2225 “F). Do not forge after temperature of forging stock drops below approsimately 870 “C t 1600 “F). Slow cooling is recommended
Recommended Normalizing.
Heat Treating
Forge Normalize
l
AL\nnlal
l
Rough machine Austenitize and quench Temper Finish machine
l
Heat to 870 “C t I600 “FL Cool in air
Processing
l
l
Practice
After quenching. reheat immediately to the tempering provide the required strength and/or hardness
Recommended l
Forging.
Heat to 8-U “C t 1555 “F). and quench in oil. Flame hardengas nitriding. and carbonitriding are suitable processes
l
Sequence
4147, 4147H: Hardness vs Tempering Temperature. sents an average based on a fully quenched structure
4147H: End-Quench Hardenability Distance from quenched surface l/16 in. mm I
Hardness, ARC max mia
Distance from quenched surface l/16 in. mm
Hardness, HRC max min
;7
I.58 4.71 3.16
64 64
57 56 57
IS I-l IS
'054 22.12 23.70
61 61 60
49 43 46
-I 5
6.32 7.90
64 63
56 55
16 18
25.28 28.4-I
60 59
4s 12
6 7 8
9.18 I I.06 12.64
63 63 63
55 5s 51
20 22 34
31.60 34.76 37.92
59 St? 57
40 39 38
9 IO
11.22 IS.80
63 62
s-l 53
26 28
-l I .08 44.24
57 57
37 Sl
II I2
17.38 18.96
62 62
52 51
30 32
47.40 SO.56
56 56
37 36
tem-
Repre-
Alloy Steel I333
4147H: Hardenability Curves. Heat-treating (1600 “F). Austenitize:
Hardness purposes I distance, mm 1.5 3 5 7 9 11 13 15 20 25 30 35 to 15 50
iardn ess wrposes I distance. 46in.
0 1 2 3 4 5 6 8 !O 12 !4 !6 18 IO I2
845 “C (1555 “F)
limits for specification Eardness,ERC Maximum hlinimum 64 64 64 64 63 63 63 63 62 60 59 58 57 57 56
57 57 56 55 55 55 54 53 50 45 42 39 37 36 36
limits for specification Eardness, Maximum 64 64 64 64 63 63 63 63 63 62 62 62 61 61 60 60 59 59 58 57 57 57 56 56
HRC hlinimum 57 57 56 56 55 55 55 54 54 53 52 51 49 48 46 45 42 40 39 38 37 37 37 36
temperatures
recommended
by SAE. Normalize (for forged or rolled specimens
only): 870 “C
334 / Heat Treater’s
Guide
4147: Isothermal Transformation
Diagram. Composition:
0.46 C, 0.77 Mn, 0.016 P, 0.025 S, 0.28 Si, 0.15 Ni. 1.06 Cr, 0.22 MO
334 / Heat Treater’s Guide
4150,415OH Chemical Composition.
4150. AISI and UNS: 0.18
to
0.53
c.
0.75
Recommended
to 1.00 Mn.0.035 Pmax, 0.04OS max. 0.15 100.30 Si.0.8010 I. IOCr.0.1.5 to 0.25 MO. UNS 641500 and SAE/AISI 4150A: 0.47 to 0.53 C. 0.65 to I.10 Mn. 0.15 to 0.35 Si, 0.75 to I.20 Cr. 0.15 to 0.25 MO
Normalizing.
Similar Steels (U.S. and/or Foreign). 4150.
Annealing.
UNS
G-~I~OO: ASTM A322. A331, ASOS. ASl9; MfL SPEC MLL-S-I I595 (ORD-IISO); SAE J404, J412, J770; (Ger.) DIN 1.7228: (Jap.) JJS SCM 5 H, SChl 5.
4150H. UNS H41500; ASTM A304; SAE Jl268; (Ger.) DIN I .7228; (Jap.) JIS SCM 5 H. SCM 5
Characteristics. High-hardenability steel. capable of being heat treated to high levels of strength. When the carbon content is on the higher side of the allowable range (0.53%). as-quenched hardness can approach 65 HRC. Characteristics are generally the same as those given for 314SH and 4147H. Minor differences because of higher carbon content include higher as-quenched hardness, an upward shift of the hardenability band. and an even greater tendency to cracking during heat processing Forging. Heat to 1220 “C (2275 “F). Do not forge after temperature of forging stock drops below approximately 870 “C (1600 “F). Slow cooling is recommended
Heat Treating
Practice
Heat to 870 “C ( I600 “F). Cool in air.
Jn aerospace practice.
normalize
at 870 “C (I 600 “F)
For a predominately pearlitic structure, heat to 830 “C (I 525 “F), cool fairly rapidly to 71.5 C (I370 “F). then to 670 “C (1240 “F’) at a rate not to exceed 8 “C ( I5 “F) per h; or heat to 830 “C ( I525 “F), cool rapidly to 675 YY ( I245 “F). and hold for 6 h. For a predominately ferritic and spheroidized carbide structure. heat to 750 “C (1380 “F). cool to 670 “C ( I210 “F) at a rate not to exceed 6 “C ( IO “F) per h: or cool fairly rapidly from 750 “C ( I380 “F) to 660 “C ( 1220 “FL and hold for IO h. In aerospace practice. anneal at 830 “C ( I525 “F). Cool below 540 “C ( 1000 “F) at a rate not to exceed I IO “C (200 “F) per h
Hardening. Heat to 8-15 “C ( IS55 “F). and quench in oil or polymer. Flame hardening, boriding, ion nitriding. gas nitriding. carbonitriding. austempering and martempering are candidate processes. In aerospace practice, parts are austenitized at 830 “C ( IS25 “F). and are quenched with oil or polymer Tempering.
After quenching, reheat immediately to the tempering temperature that will provide the required strength and/or hardness. See table
Alloy Steel / 335 Recommended l
Forge Normalize
l
Anneal
l
l l l l
Processing
Sequence
4150:
As-Quenched
Specimens
Hardness
quenched in oil
Size round
Rough machine Austenitize and quench Temper Finish machine
In.
‘/z I 2 4
mm 13 25 91 102
Surface
Eardness, ERC % radrus
Ceoler
64 62 58 47
64 62 57 43
63 62 56 42
Source: Bethlehem Steel
4150: Continuous Cooling Transformation
Diagram. Composition:
0.50 C, 0.85 Mn, 0.020 P. 0.020 S, 0.25 Si, 1 .OOCr, 0.22 MO. Austeni-
tized at 850 “C (1560 “F)
4150: End-Quench Hardenability.
Use of successively higher austenitizing temperatures. Composition: 0.55 C, 0.84 Mn. 0.30 Si, 0.13 Ni, 0.92 Cr, 0.21 MO
336 / Heat Treater’s
Guide
4150H: Hardenability
Curves. Heat-treating 845 “C (1555 “F)
(1600 “F). Austenitize:
Hardness purposes
limits for specification
J distance, mm
Hardness, HRC Maximum hlinimum
1.5 3 5 7 9 11 13 15 20 25 30 35 40 45 50
Hardness purposes J distance, I46 in. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 18 20 22 24 26 28 30 32
65 65 65 65 65 65 65 64 63 62 61 60 59 58 58
limits
59 59 58 58 57 57 56 55 51 47 44 41 39 38 38
for specification Hardness, ARC Maximum hlinimum 65 65 65 65 65 65 65 64 64 64 64 63 63 62 62 62 61 60 59 59 58 58 58 58
59 59 59 58 58 57 57 56 56 55 54 53 51 50 48 47 45 43 41 40 39 38 38 38
temperatures
recommended
by SAE. Normalize (for forged or rolled specimens
only): 870 “C
Alloy Steel I337
4150H: End-Quench Hardenability Distance from quenched surface &in. mm
Hardness. HRC mah min
Distance from quenched surface
‘/16h.
mm
Hardness. HRC ma\: min
7I ;
I .S8
69
59
I?
10.5-l
63
51
1.74 3 lb
6S bS
59
15 I-1
23 70 21.1:
b2 62
18 50
.I s 6
6 32 I 90 9.48
65 65 6.5
58 S8 Sl
I6 I8 20
25.3 28.44 3 I .hO
b2 61
47 4s
bO
-I3
8 9 I0
1
II.06 12.6-l l-1.2’ IS.80
6S 6-I 61 64
57 S6
22 21 lb
31.16
Sb
37.9: 4l.08
59 59 58
-II 10 39 38
II I2
17.38 18.96
6-l 63
s-l 53
30 31
47.40
58
SO.Sb
SY
38 38
S5
28
44.2-l
58
4150, 4150H: Hardness vs Tempering Temperature. Repre-
4150: Hardness vs Tempering Temperature. Normalized at 870
sents an average based on a fully quenched structure
“C (1600 “F), quenched from 845 “C (1555 “F), and tempered in 56 “C (100 “F) intervals in 13.716 mm (0.540 in.) rounds. Tested in 12.827 mm (0.505 in.) rounds. Source: Republic Steel
4150: Suggested Tempering Temperatures (Aerospace Practice)(a) 860-1035 hlPa (125l50bi)
Tensile strength ranges 1035-1175 hlPa 1175-1240 MPa (150-170 ksi) (170-180 ksi)
650 “C (IXIO’F, ~a)Qurnch
59s “C (I lOO”F, ~iioilorpol~mrr.
53 “C (975 “F)
Source: .~hlS ?7S9/l
1240-1380 hlPa (180-200 hi) 41s “C lXOO”F,
Alloy Steel I337
4161,4161H, Chemical
4161RH
Composition.
4161. AISIand UNS: 0.56 to 0.64 C, 0.75 to 1.00 Mn, 0.035 P max, 0.040 S max. 0.15 to 0.30 Si, 0.70 to 0.90 Cr, 0.25 to 0.35 MO. UNS H41610 and SAE/AISI 4161H: 0.55 to 0.65 C, 0.65 to 1.10 Mn, 0.15 to 0.35 Si, 0.65 to 0.95 Cr. 0.25 to 0.35 M O. SAE 4161RI-I: 0.56 to 0.64 C, 0.75 to 1.00 Mn, 0.15 to 0.35 Si, 0.70 to 0.90 Cr, 0.25 to 0.35 MO
Similar Steels (U.S. and/or Foreign). 4161. UNS ASTM A322, A33 1; SAE J404,54 12,5770.4161H. UNS H4 1610; ASTM A304, A914; SAE 51268
Characteristics. A high-carbon steel, with a mean carbon content of 0.60%, has the highest carbon content of the 4100 steels. Chromium content is lower and the molybdenum content is higher than that of 4150H and other steels in the 4100 series. As a result. hardenability is higher. The band shows clearly that when all elements affecting hardenability are on the high side, the upper line of the band approaches that of an air-hardening steel, nearly a straight line. Depending on the precise carbon content, as-quenched hardness for 4161 H ranges From 60 to 65 HRC. Often used for various tool, die, and spring applications. Well suited for heat treating by
338 / Heat Treater’s
Guide
the austempcring process. MUSI he mated CiUCfully in all hcitt prowssing iIpplications lo avoid cracking
g;lS nilriding. austcmpcring.
Forging. ~~cat IO 120~ “C (2200 “t:). DO not I’ogc alicr tcmpcraturc of Ibr@ng stock drops hclow approximntcly X70 “C (IMX) “F). Forgings should Aways IX COOM SIOWIY IO itvoid critcking
Tempering.
Recommended Normalizing.
Heat Treating
iulslcmpcring, iilld c;whonilriding urc Slliliiblc quenching is in iI molten salt bath
proccsscs.
Bcforc parts rc;rh room tcmpcritturc. tcmpcr immcdiatcly. 38 10 SO “C (IO0 to I20 “F) is idcitl. ‘I’hc tcmpcring tcmpcraturc depends upon the dcsircd h;rrdncss or combination of’ propcrtics
Austempering. Austcnitize ai X30 “C ( IS25 “I:), quench into a wcllilpiti~tcd I~ICII SCIIIhilth ill 3 I5 ‘7’ (000 “F). hdtl Ibr 2 h, imd COOI in ;Gr. No tcmpcring is rcquirctl
Practice
Hcai IO X55 “C: (IS70 “I:). C:ool in air
Annealing.
For subscqucnt milchinine or opcmtinns involved in I;lhricw ing P;UIS. B prcdominatcly sphcroidizcd micmstmcturc is usually prcliirrcd. This cun hc uchievcd hy hwing IO 760 “C (IWO “F), cooling to 705 “C’ (IBOO ‘19 81 iI riitc not IO cxcccd 6 “C: ( IO “l;) per h; or by heating IO 760 “C‘ ( I4W “F). cooling f;iirly ntpidly to (,(A) “CT ( I220 “19, imd holding Ihr IO h
Hardening.
I lcilt to X30 “c’ ( IS25 “I’), itlId quench in oil. Thin sections may be I’ully hardcncd hy ;tir cooling liom XBO “C ( IS25 “F). Ion nitriding.
Recommended
Processing
l
IGgc Normali/.c
l
,\lllKxil
l
KOUgh
l
iId quench (or ;tustcmpcr) Tcmpcr (or ilustcmpcr) Finish m;rchinc (or illlStClllpCr)
l
l l
Sequence
lllilChillC
Au~~cl~i~izc
4161H: End-Quench Hardenability Distance frum quenched surface 916 in. mm
I 2 3 4 s 6 7 x 0 IO II 12
I.58 3.10 4.14 6.32 7.90 9.18 I I .ofl 12.64 14.22 IS.XO 17.38 I x.96
Hnrdness, HWC IIIPX min
0.5 OS 05 65 OS 6.5 h5 OS 65 65 65 6-l
60 bo ho 60 60 OfI h0 b0 SJ 59 59 so
Iktnncc liw~~~ quenched surface l/16 in. mm
13 I3 IS I0 IX 20 22 2-l 26 2x 30 32
20.5-I 22.12 23.70 2.5.28 2x.44 3 I .60 31.76 37.92 41.0x 4J.ZJ 17.40 5050
Iii
Hardness, HHC mnx min
04 64 03 61 6-t 03 (13 63 h3 03 0.3 0.3
5X 5x 57 so 5s 53 SO 3x 45 43 42 .II
4161, 4161H: Hardness vs Tempering Temperature. sents an average
based
on a fully quenched
structure
Repre-
Alloy Steel / 339
4161 H: Hardenability
Curves. Heat-treating temperatures
(1600 “F). Austenitize:
845 “C (1555 “F)
iardness wrposes distance, Im .5
1 3 5 0 5 0 5 0 5 0
lardness iurposes distance. 16h.
0 1 2 3 4 5 6 8 0 2 4 6 8 0 7
limits for specification Earduess, Maximum
ERC Minimum
65 65 65 65 65 65 65 65 65 64 63 63 63 63 63
60 60 60 60 60 60 60 60 58 56 53 50 46 43 41
limits for specification Eardness, Maximum 65 65 65 65 65 65 65 65 65 65 65 64 64 64 64 64 64 63 63 63 63 63 63 63
HRC hliuimum 60 60 60 60 60 60 60 60 59 59 59 59 58 58 57 56 55 53 50 48 45 43 42 41
recommended
by SAE. Normalize (for forged or rolled specimens
only): 870 “C
340 / Heat T
reater’s
4161RH: Hardenability “C (1800 “F). Austenitize:
Hardness purposes J distance, %6 in. 1 2 3 4 5 5 7 B 3 10 11 12 13 14 15 16 18 20 22 z4 26 28 30 32
Hardness purposes J distance,
‘/I6in. 1.5 3 5 7 9 11 13 15 20 25 30 35 40 45 50
Guide
Curves. Heat-treating 845 “C (1555 “F)
limits for specification Eardness. Maximum
HRC Minimum 60 60 60 60 60 60 60 60 60 60 60 59 59 59 58 57 56 54 53 51 49 47 46 45
65 65 65 65 65 65 65 65 65 65 65 64 64 64 63 63 62 62 61 60 59 58 57 57
limits for specification Hardness, Maximum 65 65 65 65 65 65 65 65 64 63 62 61 59 58 57
HRC Minimum
60 60 60 60 60 60 60 60 59 51 55 53 50 4-l 45
temperatures
recommended
by SAE. Normalize (for forged or rolled specimens
only): 870
Alloy Steel / 341
4320,4320H,
4320RH
Chemical Composition. 4320. AISI and UNS: 0.17 to 0.11 C. O.-Is too.65 h~n.0.035Pmax.0.O-l0Smax.0.15to0.30Si. 1.65to7.00Ni.0.-10 to 0.60 Cr. 0.20 to 0.30 MO. IJNS H43200 and SAE/AISI 4320H: 0. I7 to 0.23 C. 0.10 to 0.70 Mn. 0.15 IO 0.35 Si, 1.55 to 2.00 Ni. 0.35 to 0.65 Cr. 0.20 to 0.30 MO. SAE 4320RH: 0. I7 to 0.21 C. O.-IS to 0.65 hln. 0.15 to 0.35 Si, 1.65 to 2.00 Ni, O.-l0 to 0.60 Cr. 0.20 to 0.30 hlo Similar Steels (U.S. and/or Foreign).
4320. UNS G~3200: ASThl A322. A33 I, A505, ASl9. A535; SAE J1O-k. J-II?. J770.43208. UNS H13200; ASTM A30-L A9l-l; SAE J 1268. J IX68
Annealing. Not usually annealed for a pearlitic structure because machinahility is better \i hen the predominate structure is spheroidal carbide. This is best obtained by heating after normalizing (following forging or rolling). to 775 “C ( IQ5 “Fj. cooling rapidly to 650 “C (I300 “F). then holding for 8 h Tempering. Tempering of carburized or carhonitrided parts made from 1320H is always recommended. Tempering temperature should be at least I SO “C (300 “F). Somen hat higher tempering temperatures may be used if some hardness can be traded off for increased toughness Case Hardening.
Characteristics.
Used almost exclusively for carhurizing applications, notably heavy-duty. heavy-section pears. pi-tions. and related machinery components. Can be directlq hardened to 10 HRC or higher through relativeI) thick sections hecause of hiph hardenability. Use of -l330H. hoiiever. is far less errtensiLe \h hen compared with most other allo> carburizing steels because it costs more. and hecause its properties (relating mainly to hardenability) are not required for a maJority of applications. Forgeable and ueldable. but has relatively poor machinahilir).
Carburizing procedures are the same as those given for 31 I XH. -13XH can be carbonitrided, although this process is infrequently applied. Parts made from 1320H are not. as a rule. well suited to the carbonitriding process. If used. see carbonitriding procedure described for grade -II l8H. Gas carhuriring. ion nitriding, austempering. and martemperin~ are altematke processes
Recommended l l
Forging.
Heat to 17-15 “C. (2275 “F) maxmium. Do not forge after temperature of forging stock drops below approsimately 870 “C ( 1600 OF)
l l l
Recommended
Heat Treating
Practice
l l
Normalizing. 4320:
Heat to 925 “C ( 1695 “FL Cool in air
Carburizing,
Processing
Sequence
Forge Normalize Anneal Rough and semifinish machine Carburizc and harden Temper Finish machine (usually grinding. removing total case per side from critical areas)
no more than IO% of the
Single Heat Results
Specimens contained 0.20 C. 0.59 Mn, 0.021 P, 0.018 S, 0.25 Si, 1.77 Ni, 0.47 Cr, 0.23 MO; grain size was 6 to 8; critical 1350 “F (730 “C); AC,, 1485 “F (805 “C); Ar,, 1330 “F (720 “C); Ar,, 840 “F (450 “C); 0.565-in. (14.4-mm) round treated, round tested Elongation
case
Recommended practice
Hardness, ERC
in.
mm
60.5 62.5 62
0.060 0.075 0.075
I.52 1.91 1.91
217 218.3 151.75
I-196 I505 lo46
159.S I78 97
I loo 12’7 669
5X 5 59 59
0.060 0.07S O.07S
I .s2 I.91 I.91
215.5 211,s 115.75
I186 I-158 IOOS
158.75 173 91.S
1095 1193 652
Depth
Tensile strength ksi MPa
Yield point ksi hiPa
in2in. (50mm),
points Included AC,, 0.505-in. (12.8-mm)
Reduction ofarea,
I&lldlll?SS,
*
EB
13.0 13.5 19.5
so. I 48.2 49.-l
429 429 302
12.5 l2.S 21.8
19.J so.9 56.3
415 115 293
Q
For maximum case hardness Direct quench from pot(a) Single quench and rempert bl Double quench and tempertc~
For maximum core toughness Direct quench from pot(d) Smplr quench and temper(e) Double quench and tempert fl
(a~ Carburizcd at 1700 “F t925 “C) for 8 h. quenched in agitated oil. tempered at 300 “F ( I SO ‘T I. I b, Carburircd at I700 “F t92S “C I for 8 h. pot cooled. reheated to I500 OF (8 I5 “CL quenched in agitated oil. tempered at 300 “F t I50 T). Good case and core properties. ic) Carbunred at I700 “F t92.i “C) for 8 h. pot cooled. reheated to IS00 “F (815 “C), quenched inagitatedoil, reheated to 142YFt77S “C).qucnchrd inagitatrdoil. tempered at 3tW)“Fl ISOTI hlavirnum refinement ofcaseandcore. td)Carburizedat 17OO”F(925 ‘T) for 8 h. quenched in agitated oil. tempered at 1SO “F (130 “C). tr) Carburirrd at I700 ‘F (925 “C, ior 8 h. pot cooled. reheated to IS00 “F 18lS “C). quenched in agitated oil. tcmperedat150°Ft23t)“C~. Good cujemd core properties of) Carbutized at 17OO”Ft925 “CT) for8 h. pot cooled. reheated to lSOWFt8lS “C). quenched inagitatedoil. reheated to 1425 “F(775 “Ckquenchrd in agttatrd oil. temperedat -lSO”Ftl30”C~. hlaximum refinement ofcaseandcore. tsourcc: Bethlehem Steel)
4320: Surface Carbon Content after Carburizing. 25.4 mm
(1 tn.) diam bar, 26 tests. Carburized at 925 “C (1695 “F)using a diffusion cycle, quenched from 815 “C (1500 “F) in oil at 60 “C (140 “F), tempered at 650 “C (1200 “F). Dew point, -1 “C (30 “F) at discharge end. Desired carbon concentration, 0.85 0.05%
342 / Heat Treater’s Guide
4320H: End-Quench Hardenability Diitmce from quenched surface ‘/,6 in.
Eardness, ERC
mm
man
min
Dice Prom quenched surface ‘/la in. mm
Eardoess, ERC maw
I 2
I .58 3.16
48 47
?I 38
13 I-1
20.54 22.12
28 27
3
4.74 6.32 7.90 9.48 II.06 12.64 14.22 15.80 17.38 I&%
45 13 41 38 36 34 33 31 30 29
35 32 29 27 25 23 22 21 20 20
IS I6 18 20 22 2-l 26 28 30 32
23.70 25.28 28.4-l 31.60 34.76 37.92 41.08 44.2-l -+7.40 SO.56
27 26 25 25 24 2-t 2-l 2-l 24 24
4
5 6 7 8 9 IO II I2
4320: Effect of Prior Microstructure on Hardness after Tempering. Specimens tempered 2 h
4320, 4320H: Hardness vs Tempering Temperature. Represents an average based on a fully quenched structure
4320:
As-Quenched Hardness
Specimens
were quenched
in oil.
Size round in.
mm
‘/2
I3 25 51 102
I 2 4 Source: Bethlehem
Steel
Surface 44.5 39 35 25
Eardness, HRC L/zradius 44.5 37 30 2-l
Center 44.5 36 27 23
Alloy Steel / 343
4320H: Hardenability Curves. Heat-treating (1700 “F). Austenitize:
hardness wrposes I distance, nm .5
1 3 5 !O !5 LO 15 lo 15 in
925 “C (1700 “F)
limits for specification Earduess, ERC Maximum Minimum 48 47 45 42 39 36 34 32 28 26
41 39 35 30 21 25 23 22
. ..
25 25 24 24 24
. ... ..
hardness limits for specification wrposes distance.
‘16io.
Eardness, HRC Mxximum Minimum 48 41 45 43 41 38 36 34 33 31 30 29 28 21 21 26 25 25 24 24 24 24 24
41 38 35 32 29 21 25 23 22 21 20 20
. .. .. . .
...
temperatures
recommended
by SAE. Normalize (for forged or rolled specimens
only): 925 “C
344 / Heat Treater’s Guide
4320: CCT Diagram. Carburizing composition: 0.20 C, 0.28 Si, 0.57 Mn, 0.0113P. 0.022 S, 0.50 Cr, 1.83 Ni. 0.26 MO. Alaboratory, induction air melted heat; ingot was forged to 12.7 mm (0.5 in.) square bar stock heated at 925 “C (1700 “F) for 1 h and air cooled. Steel was austenitized for 20 min at 925 “C (1700 “F). Source: Datasheet l-57. Climax Molybdenum Company
Alloy Steel / 345
4320: Cooling Curve. Half cooling time. Source: Datasheet
l-57. Climax Molybdenum
Company
346 / Heat Treater’s Guide
4320RH: Hardenability Curves. Heat-treating temperatures “C (1700 “F). Austenitize:
925 “C (1700 “F)
Hardness limits for specification purposes J distance, 916in. 1 2 3 4 5 6 7 8 9 10 II 12 13 14 IS 16 18 20 22 24 26 28 30 32
Ehrdoess, ERC Maximum Minimum 47 46 44 41 39 36 34 32 31 29 28 26 25 24 24 23 22 22 II 21 21 21 21 21
42 40 37 34 31 29 27 25 23 23 22 21 20
Hardness limits for specification purposes J distance, null 1.5 3 5 1 9 II I3 IS 20 25 30 35 -lo 35 SO
Hardness, ERC Maximum Minimum 41 46 44 40 31 34 31 30 25 23 22 21 21 21 II
42 40 31 33 30 21 25 23 20
recommended
by SAE. Normalize (for forged or rolled specimens
only): 925
Alloy Steel / 347
4330v Chemical
COIIIpOSitiOn:
AISI
4330V. 0.30 C. I.80 Ni. 0.80 Cr. 0.30
MO. 0.07 V steel
Austenitizing.
Characteristics.
An aerospace grade steel (AMS 2759/l)
Recommended Normalizing.
Annealing.
Heat Treating Practice
Heat to 900 ‘22 (1650 “F)
Heat to 855 “c ( I 575 OF)
Temperature is 870 “C (1600 “F). Hardening quenchants are oils or polymers
Alloy Steel I347
4335v Chemical
Composition.
AISI 433SV.0.35C. I .80Ni.
MO. 0.2 V steel
Characteristics.
An aerospace grade steel (AMS
Recommended Normalizing.
Heat Treating
Heat to 900 “C ( I 650 “F)
2759/l)
Practice
0.72 Cr. 0.35
Annealing.
Heat to 845 “C ( 1555 ‘W
Austenitizing. Temperature chants are oils or polymers
is 870 “C (1600
“F),
Hardening
quen-
Alloy Steel I347
4340,434OH Chemical Composition. 4340. AISI and UNS: to0.80Mn.0.035 Pmax,0.040Smax.0.15to0.30Si, to 0.90 Cr. 0.20 to 0.30 MO. 4340H. AISI and UN!? too.95 Mn.0.025 Pmax.0.025S max.0.15 too.35 Si. to 0.95 Cr. 0.20 to 0.30 MO
0.38 to 0.43 C. 0.60 1.65to2.00Ni.0.70 0.37 to 0.44 C. 0.60 I.55 to2.00Ni.0.65
Similar
Steels (U.S. and/or Foreign). 4340. UNSG43-100: AMS 533 I, 6359.6413.64lS; ASTM A322. A33 I. A505, A5 19, A5-t7. A646: MJLSPEC hUL-S-16971; SAEJIO-L J-412. J770;(Ger.) DIN 1.656S:(Jap.) JIS SNCM 8; (U.K.) B.S. 817 M 40.31 I I Type 6.2 S 119.3 S 95. UJOH: UNS H43100; ASTM A3M; SAE 5407; (Ger.) DIN 1.6565: (Jap.) JIS SNCM 8; (U.K.) B.S. 817 M GO.31 I I Type 6.2 S 119.3 S 95 Characteristics. A high-hardenability steel, higher in hardenability than any other standard AlSl grade. When the elements that contribute to hardenability are on the high side of their allowable ranges, the upper curve of the hardenability band is virtually a straight line. thus indicating that 4340H would be ah-hardening in thin sections. Depending on the precise carbon content, as-quenched hardness ranges from 54 to 59 HRC. Because of high hardenability. 4340H is not considered suitable for welding by conventional means. although it can be welded by sophisticated processes such as electron beam welding. 434OH can be forged \rithout difftculty, although its hot strength is considerably higher than that of carbon or loher alloy grades, requiring more powerful forging machines. Machinability is relatively poor
Annealing.
For a predominately pearlitic structure (not usuaUy preferred for this grade). heat to 830 “C ( I525 “F), cool rapidly to 705 “C (I 300 “F), then to 565 “C ( 1050 “F) at a rate not to exceed 8 “C ( 15 “F) per h: or heat to 830 “C ( I525 “F), cool rapidly to 650 “C ( I200 “F). and hold for 8 h. For a predominately spheroidized structure. heat to 750 “C (1380 “F). cool rapidly to 705 “C ( I300 “F) then cool to 565 “C ( I050 “F) at a rate not to exceed 3 “C (5 “F) per h: or heat to 750 “C (I 380 “F). cool rapidly to 650 “C ( I200 “F). and hold for 12 h. A spheroidized structure is usually preferred for both machining and heat treating
Hardening. Austenitize at 815 “C (1555 “F). and quench in oil. Thin sections may be fully hardened by air cooling Tempering.
In common with all susceptible to quench cracking. Before to 50 “C. 100 to 120 “F), they should Tempering temperature depends upon of mechanical properties
Nitriding. Can be nitrided to produce high surface hardness and for increased fatigue strength. See processing procedure given for 414OH
Recommended l
Forging.
Heat to I230 “C (2250 “F). Do not forge after temperature of forging stock drops below approximately 900 “C (1650 “F). Slow cooling from forging is recommended to prevent the possibility of cracking
Recommended Normalizing.
Heat Treating
Practice
Heat to 870 “C ( 1600 “F). Cool in air
high-hardenability steels, 4340H is parts reach ambient temperature (38 be placed in the tempering furnace. the desired hardness or combination
l l l l l l
Processing
Forge Normalize Anneal Rough machine Austenitize, quench. and temper Finish machine Nitride (optional)
Sequence
348 / Heat Treater’s
Guide
4340: Isothermal Transformation Grain size: 7 to 8
Diagram.
Composition:
0.42 C. 0.78 Mn, 1.79 Ni, 0.80 Cr. 0.33 MO. Austenitized
at 845 “C (1555 “F).
4340: Cooling Transformation Diagram. Composition: 0.41 C. 0.87 Mn, 0.28 Si, 1.83 Ni, 0.72 Cr, 0.20 MO. Austenitized at 845 “C (1555 “F). Grain size: 7. AC,, 755 “C (1390 “F); AC,, 720 “C (1330 “F). A: austenite, F: ferrite, 8: bainite, M: martensite. Source: Bethlehem Steel
Alloy
Steel / 349
4340 + Si: End-Quench
Hardenability. Composition: 0.42 C, 0.83 Mn, 1.5 Si, 1.85 Ni, 0.90 Cr, 0.41 MO. Quenched from 845 “C (1555 “F). Source: Bethlehem Steel
4340: Tempered Hardness Versus Austenitizing Temperature and Section Size Specimens
Austenitizing temperature “F(“C) 1500(815)
were quenched
Section Size
ill.
mm
%
12.7 31.8 54 12.7 31.8 54 12.7 31.8 54
1 L/4 21/s 1550(845)
% 1 vi.4 21/8
1600 (870)
‘h 1% 2%
in oil. Aardness, ARC Tempered for 2 h at 400°F 6OO’F 8OO’F 1000°F 1200°F (205OC) (315OC) (125’C) (S-lO°C) (65OOC) 53.5 53.5 51.0 53.5 53.0 52.0 53.5 53.5 52.5
50.0 50.0
49.0 49.5 50.0 48.0 50.0 50.0 48.5
44.5 45.5
44.0 44.0 45.0 43.0 45.0 45.5
44.0
39.0
40.0 37.5 39.0 39.5 38.0
40.0 39.5 39.0
29.5 28.5 28.0 29.0 27.0 27.5 29.5 29.0 28.0
4340 + Si: Cooling Transformation Diagram. Composition: 0.43 C, 0.83 Mn, 1.55 Si, 1.84 Ni, 0.91 Cr, 0.40 MO, 0.12 V, 0.083 Al. Austenitized at 845 “C (1555 “F). Grain size: 8. AC,, 805 “C (1480 “F); AC,, 760 “C (1400 “F). A: austenite, F: ferrite, B: bainite, M: martensite. Source: Bethlehem Steel
350 / Heat Treater’s
Guide
4340H: End-Quench Hardenability Distance from quenched surface &in. mm I
2 3 4 5 6 7 8 9 10 II I?
1.58 3.16 4.74 6.32 7.90 9.48 Ii.06 12.64 14.22 15.80 17.38 IS.96
Ehrdoess, ERC max min
60 60 60 60 60 60 60 60 60 60 59 59
53 53 53 53 53 53 53 52 52 52 51 51
4340: End-Quench Hardenability.
Distance from quenched surface ‘116in. mm
13 14 15 16 18 20 22 21 26 28 30 32
20.5-i 22.12 23.70 25.28 28.44 31.60 34.76 37.92 41.08 44.24 47.40 SO.56
Hardness. ERC max min
59 58 58 58 58 57 57 57 57 56 56 56
SO 49 49 48 37 46 45 4-I 43 42 41 40
Influence of initial structure and time at 845 “C (1555 “F). HR: hot rolled, N: normalized, A: annealed, S: spheroidized. (a) 0 min; (b) 10 min; (c) 40 min; (d) 4 h
4340: Hardness vs Tempering Temperature. Normalized at 870 “C (1800 “F), quenched from 845 “C (1555 “F), and tempered in 56 “C (100 “F) intervals in 13.7 mm (0.540 in.) rounds. Tested in 12.8 mm (0.505 in.) rounds. Source: Republic Steel
Alloy Steel / 351
4340: Hardness vs Diameter. 0.38 to 0.43 C, 0.80 to 0.80 Mn, 0.040Pmax,0.040Smax,0.20to0.35Si, 1.65to2.00Ni,0.70to 0.90 Cr. 0.20 to 0.30 MO. Approximate critical points: AC,, 725 “C (1335 “F); AC,. 775 “C (1425 “F); Ar,, 710°C (1310 “F); Ar,, 655 “C (1210 “F). Forge at 1230 “C (2250 “F) maximum; anneal at 595 to 660 “C (1105 to 1220 “F) for a maximum hardness of 223 HB; normalize at 845 to 900 “C (1555 to 1650 “F) for an approximate hardness of 415 HB; quench in oil from 830 to 855 “C (1525 to 1570 “F). Test specimens normalized at 870 “C (1600 “F) in over-sized rounds, quenched from 845 “C (1555 “F) in oil, tempered at 540 “C (1000 “F). Tested in 12.8 mm (0.505 in.) rounds. Tests from 38 mm (1.5 in.) diam bars and over are taken at half radius position. Source: Republic Steel
4340: Nitriding. 20 to 30% dissociation.
(a) 7 h. (b) 24 h. (c) 48 h
4340 + Si: Tensile Strength, Yield Strength Elongation, and Reduction in Area. Composition: 0.43 C, 0.83 Mn, 1.55 Si, 1.84 Ni. 0.91 Cr, 0.40 MO, 0.12 V. 0.083 Al. Normalized at 900 “C (1650 “F), austenitized at 855 “C (1570 “F), quenched in agitated oil, tempered for 1 h. Source: Bethlehem Steel
352 / Heat Treater’s
Guide
4340: Gas Nitriding. Two tests. Nitrided at 550 “C (1020 “F) for 20 h, 20 to 509’0 dissociation
4340: Hardness vs Diameter. Composition:
0.38 to 0.43 C, 0.60 to0.80Mn,0.040Pmax,0.040Smax,0.20to0.35Si, 1.65t02.00 Ni, 0.70 to 0.90 Cr, 0.20 to 0.30 MO. Approximate critical points: Ac,,725”C(1335”F);Ac,,775”C(1425”F);Ar,,710”C(1310”F); Ar,, 655 “C (1210 “F). Recommended thermal treatment: forge at 1230 “C (2250 “F) maximum; anneal at 595 to 660 “C (1105 to 1220 “F) for a maximum hardness of 223 HB; normalize at 845 to 900 “C (1555 to 1650 “F) for an approximate hardness of 415 HB; quench in oil from 830 to 855 “C (1525 to 1570 “F). Test specimens normalized at 870 “C (1600 “F) in over-sized rounds, quenched from 845 “C (1555 “F) in oil, tempered at 650 “C (1200 “F). Tested in 12.8 mm (0.505 in.) rounds. Tests from 38 mm (1 l/z in.) diam bars and over are taken at half radius position. Source: Republic Steel
4340: Effect of Nitriding and Shot Peening on Fatigue Behavior. Comparison between fatigue limits of crankshafts (S-N bands) and fatigue limits for separate test bars, indicated by plotted points at right
4340: Microstructure.
2% nital, 500x. Quenched in oil from 845 “C (1555 “F) and tempered at 315 “C (600 “F). Tempered martensite
Alloy Steel / 353
E4340,
E4340H
Chemical Composition.
E-4340.AISI and ZJNS:0.38 to
O.-i3
c.
0.65 to 0.85 Mn. 0.025 P max. 0.025 S max. 0.15 to 0.30 Si. I.65 to ?.OO Ni,
0.70to 0.9OCr.O.20
100.30
MO.E434OH.AlSIaod UNS:0.37IOO.-U
C. 0.60 to 0.95 Mn. 0.025 Pmax. 0.035 S max. 0. IS to 0.30 Si. I.55 to X0 Ni. 0.65 to 0.95 Cr. 0.20 to 0.30 MO
Similar Steels (U.S. and/or Foreign). U340. ASThl A33l. A5OS. ASl9: MIL SPEC (Ger.) DIN I .6563: tJap.) JIS 40 NiCrMo Type 8. S 139. EXMOH.UNS H43406; DIN 1.6563: (Ital.) UNI 10 NiCrhlo 7,40
UNS
Gw06;
hlfL-S-5000; SAE J-W. 5770; 7. -tO NiCrMo 7 KB; (11.K.) B.S. ASThl 430-k SAE 5407: (Ger.) NiCrhlo 7 KB: (U.K.) B.S. Type
8. S 139
Characteristics. Basically a prenuum grade of 4330H. Prescribed composition carries lower maximums for hoth phosphorus and sulfur. Manganese range IS slightly higher. but this IS of little practical sipnificance. Hardennhility and other properties are the same as for conventtonal 4310H. Weldability and machinability are poor; forgeability is good. Asquenched hardness. 5-l to 59 HRC Forging.
Heat to 1230 “C t 1750 “FL Do not forge after temperature of forging stock drops helo\.r approximately 900 “C ( 1650 ‘F). Slou cooling from forging is recommended to prevent the possibility of crnching
“F). then to 565 “C t 1050 “F) at a rate not to exceed 8 “C (15 “F) per h; or heat to 830 “C ( I525 “F). cool rapidly to 650 “C ( 1300 “F), and hold for 8 h. For a predominately sphcroidized structure, heat to 7.50 “C (I 380 “F). cool rapidly to 705 ‘C (I300 “F), then to 565 “C (1050 “F) at a rate not to exceed 3 “C (5 “F) per h; or heat to 750 “C (I 380 “F), cool rapidly to 650 “C ( I200 ;F). and hold for I:! h. A spheroidized structure is usually preferred. for hoth machining and heat treating
Hardening. Austenitire at 835 “C ( IS55 “F), and quench in oil. Thin sections may be fully hardened hy air cooling Tempering.
These steels. in common with all high-hardenahility steels, are susceptible to quench crackin_e. Before parts reach ambient temperature (38 to 19 “C. or 100 to I20 OF). they should be placed in the tempering furnace. Tempering temperature depends upon the desired hardness or comhinatton of mechanical properties
Nitriding. Can he nitrided to produce high surface hardness and to increase fatigue strength. See processing procedure given for 1140H Recommended l l
Recommended Heat Treating Practice Normalizing. Heat to 870 “C (I600 “F). Cool in air Annealing. For a predominately pearlittc structure
(not usually preferred for this grade). heat to 830 “C t IS75 “F). cool rapidly to 705 “C ( I300
l l l l l
Processing
Sequence
Forge Normalize Anneal Rough machine Austenitize. quench. and temper Finish machine Nitride (optional)
E4340, E434OH: Hardness vs Tempering Temperature. Represents an average based on a fully quenched structure
354 / Heat Treater’s
Guide
E434OH: Hardenability
Curves. Heat-treating
870°C (1800 “F). Austenitize:
Hardness wrposes I distance,
nnl 1.5
i 3 II 13 15 !O !5 IO 15 lo IS i0
iardness wrposes I distance, 46h.
limits for specification Hardness, HRC MtlXhllUll Minimum 60 60 60 60 60 60 60 60 60 59 58 58 57 57 57
1 0 I 2 3 4 5 6 8 !O !2 !3 16 18 IO 2
53 53 53 53 53 53 53 53 52 51 SO 49 47 46 44
limits for specification Hardness, HRC Maximum Minimum 60 60
i
845 “C (1555 “F)
60 60 60 60 60 60 60 60 60 60 60 59 59 59 58 58 58 57 51 51 51 51
53 53 53 53 53 53 53 53 53 53 53 52 52 52 5’ i; 51 SO 49 18 47 46 4s 4-t
temperatures
recommended
by SAE. Normalize
(for forged or rolled specimens
only):
Alloy Steel I355
4615 Chemical Composition.
4615.AISI and UNS: 0. I 3 IO 0.18 c. 0.45
to0.65Mn.0.035Pmax.0.040Smax.0.15 to 0.30 MO
to0.30Si.
1.65 to2.00Ni.0.20
Similar Steels (U.S. and/or Foreign). 4142. UNS G16150; AMS 6290; ASTM A322, A331, A505: MIL SPEC MU-S-7493; SAE J404, 13 12, J770. This steel is no longer in SAE 5-W or J 4 12, but does appear in SAE J770. which is now J1397
Characteristics.
Used extensively for making parts that will be case hardened by carburizing or carbonitriding. Over a period of years, however, use has declined in favor of carburizing grades that have slightly higher carbon (for better core properties), lower nickel content. or both. Asquenched surface hardness (not carburized) can be expected to be approximately 35 to 40 HRC. and the hardenability band should be nearly the same general pattern as the one for 4620H. No AISI hardenability band for 4615. The slight difference in range of nickel content for 4615 and 4620H is not signiticant. Grade 4615 forges easily and is weldable. although alloy steel practice, in terms of preheating and postheating, should be used
Recommended Normalizing.
Heat to 1245 “C (2275 “F) maximum. Do not forge after temperature of forging stock drops below approximately 900 “C ( I650 “F)
4615: Carbon Gradients 4615 mod (cast), slight differences same carburizing
Produced
by Liquid Carburizing.
carburized at 925 “C (1695 “F) for 7 h. Indicates in gradients obtained in two furnaces using the conditions
4615: Hardness vs Tempering Temperature. average
based
on a fully quenched
structure
Heat to 925 “C (1695 OF). Cool in air
Case Hardening. See recommended carburizing, carbonitriding, and tempering procedures described for 4 I I8H. Flame hardening, liquid carburizing, austempering and martempering are alternative treatment processes
Recommended l l l l
l l
Processing
an
Sequence
Forge Normalize Anneal (optional) Rough and semifinish machine Case harden Temper Finish machine (carburized parts only)
4615: End-Quench
Hardenability.
Mn, 1.90 Ni, 0.24 MO. Austenitized
4615: Liquid Carburizing. Represents
Practice
Annealing. Not usually required for this grade. Structures that are well suited to machining are generally obtained by normalizing or by isothermal annealing after rolling or forging. Isothermal annealing may be accomplished by heating to 700 “C ( 1290 “F) and holding for 8 h
l
Forging.
Heat Treating
tests
Composition: 0.15 C, 0.63 at 925 “C (1695 “F). Grain size: 6
Case
hardness
gradients
after
10
356 / Heat Treater’s
Guide
4615: Carbon Gradients After Carburizing. (a) Carburized for 4 h at 870 “C (1600 “F); (b) Carburized for 4 h at 925 “C (1695 “F)
4615: Depth of Case vs Time and Temperature. 25 mm (1 in.) round bars, carburized at 925 “C (1695 “F), oil quenched
4615: isothermal Transformation Diagram. Composition: 0.15 C. 0.63 Mn. 1.90 Ni, 0.24 MO. Austenitized at 925 “C (1695 “F). Grain size: 8
356 / Heat Treater’s
Guide
4620,4620H,
4620RH
Chemical COIIIpOSitiOn. 1620. AIS1 and UN% 0.17 to 0.22 C. 0.15 too.65 Mn.0.035 Pmax.0.040Smax,0.15 ro0.30Si. 1.65 to3.00Ni.0.20 to 0.30 Mo. UNS A46200 and SAE/AISI 4620H: 0.17 to 0.23 C. 0.35 to 0.75 Mn. 0.15 to 0.35 Si, I.55 to 2.00 Ni. 0.20 to 0.30 hlo. SAE 4620RH: 0.17 to 0.22 C. 0.45 to 0.65 hln. 0. IS to 0.35 Si, I.65 to 2.00 Ni. 0.20 to 0.30 MO Similar
Steels (U.S. and/or
Foreign).
294; ASTM A322, A33 I, ASOS, AS35; hlfLSPEC J4 12. J770.4620H.
UNS H46200; ASTM
A304
4620. UNS G46WO; AhlS MU-S-7493; SAEJ10-I. A9 I-l; SAE J 1268. J I868
Characteristics. lrsed eswnsivel) for carburiring. Because of relativelj high nickel content. it has hern replaced in some areas with lower nickel alloys that have been developed and have hardenability and other properties equal to those of 462OH. Depending on the precise carbon content within the allouabls range. as-quenched hardness without carburizinp ranges betueen approsimately 40 to 35 HFX. Has a reasonably high hardenabilit!. Because of the relatwely high nickel content. 4620H is srronglq susceptible to retention of austenite. While retained auslenite is usually considered as an undesirahls constituent. some specific applications exist 1%here retained austenire has proved to be an advantage
Alloy Steel / 357 Forging. forging
Heat to 1245 “C (X75 “F). Do not forge after temperature stock drops helow approximateI> 815 “C (IS55 “F)
Recommended Normalizing.
Heat Treating
of
tempering procedures described pering are alternative processes
Recommended
Practice
l
Heat to 915 “C ( 1695 “F). Cool in air
l
Annealing.
Structures with best machinabilib are de\elopsd by normalizing or by isothermal transformation after rolling or forginp. Commonly used isothermal practice consists of heating to 775 ‘C (1415 “F). cooling rapidly to 650 ‘C ( I300 “F). and holding for 6 h
l
Hardening.
l
Seldom subjected to hardening treatments except carburizing and carbonitriding. See recommended carburizing. carboniu-iding. and
4620:
Carburizing,
l l l
for 41 l8H. Flame hardening
Processing
and martem-
Sequence
Forge Nomlalize Anneal (optional) Rough and semifinish machine Case harden Temper Finish machine (carburized parts only)
Single Heat Results
Specimens contained 0.17 C, 0.52 Mn, 0.017 P, 0.016 S, 0.26 Si, 1.81 Ni, 0.10 Cr, 0.21 MO; grain size 6 to 8; critical points included AC,, 1300 “F (705 “C); AC,, 1490 “F (810 “C); Ar,, 1335 “F (725 “C); Ar,, 1220 “F (660 “C); 0.565-in. (14.4-mm) round treated, 0.505-in. (12.8-mm) round tested Core properties Case Recommended practice
Elongation
Depth
Tensile strength ksi hlPa
Ill.
6’ S 62
0.07.5 0.060
.91 52
119.25 I22
822.2 811
83.5 77.25
576 532.6
19.5 72.0
59.1 55.7
277 248
58 5 59 59
0.060 0.065 0 MO
57 .6S .65
147.5 I IS.5 I IS.25
1017 796.3 794.63
I IS.75 80.75 77
798.07 556.8 531
16.8 70.5 22.5
57.9 63.6 62.1
302 318 235
mm
b’ield point ksi hIPa
Reduction Ofare& (SOmm), % 5%
Hardness, HRC
in2in.
Hardness, EIB
For maximum case hardness Direct ouench from rot(u)
Single &ench and &per(b) Double quench and temper(c)
For maximum core toughness Direct quench fmm pot(d) Single quench and temper(r) Double quench and temper(f)
(a) Carburizzd at 1700°F (925 TI for 8 h, quenched in agitated oil, tempered at 300 “F I I SO “C) 1.b) Carburized at 1700 “F (925 “C I for 8 h pot cooled. reheated to IS00 “F (815 “CJ. quenched in agitated oil, tempered at 300 “F ( 150 “CL Good case and core properties. tc) Carburizcd at I700 ‘,F 1925 “C) for 8 h. pal cooled, reheated IO IS25 “F (830 “C). quenchrdinagitatedoil.rehestedto 1175”Fi800”C).quenchcdinagiraredoil. temperedat “Ft 150°C) hlsaimumrefinemcntofcclseandcore.(d)Carburizcdat 17OO”F(925 “C). quenched in agitatedoil. tempered at -IS0 “Ft230”C) Ir) Carburircdat 1700 “Ft925 “C). pot cooled. reheated to IS00 “F18lS ‘CL quenched in agitatedoil, temperedatJS0 “F(23O”C). Goodcasesndcore propenies. (fl Carburircd at 1700 “Fi92S “C) for 8 h. pot cooled, reheated to IS25 “Ft830 “CL quenched in agitatedoil, reheated to 1175 “F(800 T). quenched in agitated oil. tempered at -IS0 “F (230 “C ). (Source: Bethlehem Steel 1
4620H: End-Quench Hardenability Distance loom quenched surface ‘/,b in. mm
Hardness, HRC min max
Distance from quenched surface &in. mm
Hardness, HRC may
I
I.58
48
-II
I3
20.54
12
1 -I 5 6 7
3.16 4.74 6.32 7.90 9.48 ll.c6
J5 -II 39 3-I 31 29
3s 27 2-l 21
I4 IS I6 I8 20 2’
21.12 23.70 ‘5 ‘8 5s:; 3160 31.76
22 22 ‘I 21 20
8 9 IO II I2
12.6-I I-l.22 15.80 17.38 18.96
27 26 2s 2-l 23
24 26 33 30 32
37.92 41 08 44.21 47.40 SO.56
3
358 / Heat Treater’s
Guide
4620H: Effects of Carburizing 63 HRC
and Quenching
Methods
on Dimensions.
Gears, carburized
0.762 to 1.02 mm (0.030 to 0.040 in.), 58 to
Specimens 19 mm 4620: Liquid Carburizing. (.75 in.) diam by 51 mm (2 in.), carburized, air cooled, reheated in neutral salt at 845 “C (1555 “F), quenched in salt at 180 “C (360 “F). (a) Carburized at 870 “C (1600 “F); (b) Carburized at 900 “C (1650 “F); (c) Carburized at 925 “C (1695 “F)
4620: Range of Surface Carbon vs Position in Furnace. Bearing races, carburized in a pit furnace 762 mm (30 in.) in diameter by 914 mm (36 in.) deep. Open load of races was carburized for 7 h in natural gas atmosphere; 3 92 h diffusion cycle followed. Surface carbon aim was 1 .OO%. Each bar represents 14 heats of steel
Alloy
4630:
As-Quenched
Specimens
Hardness
4620, 4620H: Hardness vs Tempering Temperature. sents an average based on a fully quenched structure
quenched in oil
Repre-
HWdIlt?SS
Size round in.
mm
Surface
‘/* radius
Center
‘/:
13 25 Sl 102
40 HRC 21 HRC 23 HRC % HRB
32 HRC 99 HRB 91 HRB 91 HRB
31 HRC 97 HRB 9ZHRB 88 HRB
I 2 -l
Steel / 359
Source: Bethlehem Steel
4620: CCT Diagram. Chemical composition: 0.20 C, 0.49 Mn, 0.016 P. 0.022 S, 0.23 Si, 1.76 Ni. 0.25 MO, 0.076 Al. A laboratory induction air melted heat. Specimens 4 mm (0.16 in.) in diameter were through-carburtzed to various carbon levels by holding in a carburizing atmosphere at 1150 “C (2100 “F) for 16 to 20 h. Machined dilatometer specimens [3 mm (0.116 in. )] in diameter were austenitized and cooled at three different rates to define the partial CCT diagram at each carbon level. Cooling rates ranged from 357 to 3280 “C (675 to 5900 “F) per min. The cooling curves used to define the diagrams are not shown. Instead, the cooling curves shown were measured on impact-fracture specimens (gear tooth simulation) at locations corresponding to the surface and the case-core interface during quenching in warm oil [66 “C (150 “F)] or in hot oil [170 “C (340 “F). Specimens were austenitized at 900 “C (1650 “F) for 20 min. The objectives of the study were to obtain partial kinetic data on continuous-cooling transformation at various carbon levels in the carburized case. Hardness values (in circles on the diagram) were exhibited by specimens of each carbon level subjected to the fastest cooling rate used to define each CCT diagram. Source: Datasheet l-262, Climax Molybdenum Company
360 / Heat Treater’s
Guide
4620: Microstructures. (a) Nital, 1000x. Gas carburized at 1.000/b carbon potential for 8 h at 940 “C (1725 “F), oil quenched, heated to 820 “C (1510 “F), oil quenched, tempered 1 h at 180 “C (355 “F), retempered 2 h at 260 “C (500 “F). Composition: 0.95 C. Retained austenite (by x-ray), tempered martensite, lower bainite. carbide. (b) Nital, 1000x. Gas carburized and heat treated before tempering under same conditions as (a), but tempered 1 h at 180 “C (355 “F) and retempered 2 h at 230 “C (450 “F). 10% retained austenite (by x-ray), tempered martensite, lower bainite. dispersed carbide particles. (c) Nital, 1000x. Gas carburized and heat treated before tempering under same conditions as (a) and (b), but tempered 1 h at 180 “C (355 “F) and retempered 2 h at 220 “C (425 “F). Composition: 0.95 C. 20% retained austenite (by x-ray), tempered martensite, lower bainite, carbide. (d) Nital, 1000x. Gas carburized at 1 .OO% carbon potential for 4 h at 940 “C (1725 “F), oil quenched, and tempered for 1 h at 180 “C (355 “F). Composition: 0.90 C. 35% retained austenite (by x-ray), and tempered martensite. (e) Nital, 1000x. Gas carburized at 1.00% carbon potential for 8 h at 940 “C (1725 “F), oil quenched, heated to 820 “C (1510 “F) for 30 min. oil quenched, tempered 20 min at 94 “C (200 “F). Composition: 0.95 C. 40% retained austenite (by x-ray), and tempered martensite. (f) Nital, 1000x. Gas carburized at 1.00% carbon potential for 8 h at 940 “C (1725 “F), oil quenched, and tempered for 1 h at 180 “C (355 “F). Composition: 0.95 C. 45% retained austenite (by x-ray), and tempered martensite.
Alloy Steel / 361
4620H: Hardenability
Curves. Heat-treating
(1700 “F). Austenitize:
925 “C (1700 “F)
iardness w-poses I distance, nm
1.5 3 5 7 1 11 13 15 20 25 30 35
Hardness purposes I distance, V,6 ill.
1 2 3 4 5 6 I 8 9 10 11 12 13 14 15 16 18 20 22
limits for specification Hardness,
hlanimum
HRC hlinimum
48 46 42 37 33 30 27 26 23 22 21
41 31 28 23 . .. ..
limits for specification Hardness, MaGmum
48 45 42 39 34 31 29 27 26 25 24 23 22 22 22 21 21 20
ARC hlinimum
41 35 27 24 21
... . . .
temperatures
recommended
by SAE. Normalize (for forged or roiled specimens
only): 925 “C
1
362 / Heat Treater’s
Guide
4626,4626H Chemical COIIIpOSitiOn. 4626. AISI and UN!%: 0.2-l to 0.29 C. 0.45 to0.65Mn,0.035Pmax,0.040Smax,0.15to0.30Si,0.70to l.00Ni.0.15 to0.25Mo.4626E.AISIaodUNS:0.23to0.29C,0.40to0.70Mn,0.035 P max. 0.040 S max. 0.15 to 0.30 Si. 0.65 to I .05 Ni. 0.15 to 0.25 MO G46260; UNS Steels (U.S. and/or Foreign). 4626. ASTM A322. A33 I; SAE 5404.5412. J770.46268. UNS H-16260; ASTM A304 This steel is no longer in SAE 5404 or J3 12. but does appear in SAE 5770. which is now J I397
Annealing.
Best structures for machining are obtained either by normalizing or by isothermal treatment after rolling or forging. Isothermal treatment is accomplished by heating to 815 “C (1500 “F). cooling rapidly to 675 “C ( I235 “F). and holding for 8 h
Similar
Characteristics.
Usually used for carburizing or carbonitriding applications, although because of the as-quenched hardness of approximately 43 to 48 HRC that can be developed, it is sometimes used for parts that require strength and toughness without case hardening. To save energy. 4626H is sometimes used rather than lower carbon steels for carburizing. because the harder cores provided by 4626H often permit thinner cases. decreasing the required carburizing time. The hardenability of 4626H is slightly lower than shown for 4620H. because of the lower alloy content of 4626H. Can be welded, but alloy steel practice must be used
Direct Hardening. Tempering.
Temper to at least 205 “C (100 OF) and preferably some loss of hardness can be tolerated
Case Hardening. tempering
Forging.
Heat to 1230 “C (2250 “F) maximum. Do not forge after of forging stock drops below approximately 870 “C ( 1600 “F)
Recommended Normalizing.
Heat Treating
l
I 2 3 4 5 6 7 8 9 IO II I2
I S8 3.16 4.74 6.32 7.90 9.48 II.06 12.6-I I-t.22 15.80 Il.38
18.96
l
See recommended carburizing, described for 41 l8H
Processing
higher if
carbonitriding.
Sequence
Forge Normalize Anneal (optional) Rough and semifinish machine Case harden or direct harden Temper Finish machine (carburized parts only)
Hardenability
Distance from quenched surface &III. mm
l
l
Heat to 900 “C (1650 “F). Cool in air
4626H: End-Quench
l
l
Practice
procedures
Recommended l
temperature
Heat to 870 “C (1600 “F) and quench in oil. Caris a suitable hardening process
bonitriding
Eardness, ERC min max 51 38 41 33 29 27 25 24 23 22 22 21
4s 36 29 24 II
Distance from quenched surface ‘/,a in. mm I3 IJ IS I6 I8 20 22 ‘4 26
20.5-l
22.12 23.10 25.28 28.44 31.60 3-1.16 31.92 AI.08
Ehl-dlleSS,
HRC max 21 20 .._ .._
4626, 4626H: sents an average
Hardness based
vs Tempering
Temperature.
on a fully quenched
structure
Repre-
and
Alloy
4626H: Hardenability
Curves. Heat-treating
(1700 “F). Austenitize:
925 “C (1700 “F)
iardness wrposes I distance, om ._5 /
, I b I 3 5 !O !5
iardness wrposes I distance, 116i”. I , I I i i
I I ) IO II 12 13 l-1 IS
limits for specification Eardness, ERC Maximum Minimum 51
45
48 38 31 27 25 2-l 23 21
36 29 23 20
limits for specification Aardness, ERC Maximum Minimum 51 48 41 33 29 27 ‘5 24 23 22 22 21 21 20
4s 36 29 24 21
temperatures
recommended
by SAE. Normalize (for forged or rolled specimens
Steel I363
only): 925 “C
364 / Heat Treater’s
Guide
4718H Chemical COI?IpOSitiOn. UNS H47180 and SAE/AISI 47188: 0. IS to 0.21 C. 0.60 to 0.95 MN, 0.15 to 0.35 Si. 0.85 to 1.25 Ni. 0.30 to 0.60 Cr. 0.30 to 0.40 Mo
4718H: Hardenability
Curves. Heat-treating 925 “C (1700 “F)
(1700 “F). Austenitize:
temperatures
Similar
Steels (U.S. and/or
Foreign).
to SAE J I268 and will appear in ASTM
recommended
This steel has heen added
A301
by SAE. Normalize (for forged or rolled specimens
only): 925 “C
Hardness limits for specification 3urposes I distance, q m
.5
Hardness, HRC hlinlmum Maximum 47 47 46 43 39 36
34 32 29 27 26 26 2s 25 24
40 40 38 31 28 25 23 22 21 20
(continued)
Alloy Steel I365
4718H: Hardenability
Curves. (continued) Heat-treating
only): 925 “C (1700 “F). Austenitize:
Hardness purposes J distance, %6 ill. I 2 3 4 5 6 7 8 9 10 II 12 13 14 15 16 18 20 22 24 26 28 30 32
925 “C (1700 “F)
limits for specification Hardness, HRC Maximum blinimum 47 47 45 43 40 37 35 33 32 31 30 29 29 28 27 27 27 26 26 25 25 24 24 24
40 40
38 33 29 27 25 24 23 22 22 21 21 21 20 20
temperatures
recommended
by SAE. Normalize (for forged or rolled specimens
366 / Heat Treater’s Guide
4720,472OH Chemical Composition.
4720.
AI!31
and UNS: 0.17 IO 0.22 C. 0.50
to0.70Mn.0.035Pmax.0.040Smax.0.15to0.30Si.0.90to l.10Ni.0.35 to 0.55 Cr. 0.15 to 0.25 MO. UNS 847200 and SAE/AISI 47208: 0. I7 to 0.23 C. 0.45 to 0.75 Mn. 0.15 to 0.35 Si. 0.85 to 1.25 Ni. 0.30 to 0.60 Cr, 0.15 too.25 MO
Similar Steels (U.S. and/or Foreign). 4720.
UNS
ASTM A274. A322. A331. A5 19, A535; SAE J404, J412,5770. UNS H47200; ASTM A304; SAE J I268
G472OO; 4720H.
Characteristics. Essentially the same as those for 4620H. The lesser nickel content of 4720H is compensated for by a chromium addition. As a result, hardenability for the two steels is nearly the same. As-quenched hardness of approximately 40 to 45 HRC is also the same. Because of the lower nickel content and the chromium addition, the tendency of 4720H to retain austenite in carburized cases is less than for 4620H. In many instances, 4720H has replaced 4620H as a carburizing steel
Recommended Normalizing.
Heat to 1230 “C (2250 “F) maximum. Do not forge after temperature of forging stock drops below approximately 845 “C ( I555 “F)
Practice
Heat to 925 “C ( 1695 “F). Cool in air
Annealing.
Best structures for machining are obtained either by normalizing or by isothermal treatment consisting of heating to 815 “C (1500 “F), cooling rapidly to 650 “C ( I300 “F). and holding for 8 h
Case Hardening. tempering
procedures
Recommended l l l l l
Forging.
Heat Treating
l l
See recommended carburizing, described for 4 I I8H
Processing
carbonitriding,
Sequence
Forge Normalize Anneal (optional) Rough and semifinish machine Case harden Temper Finish machine (carburized parts only)
4720H: End-Quench Hardenability Diicefrom quenched surface l/,/16in. mm I
2 3 4 5 6 7 8
9 IO II I2
I .58 3.16 4.14 6.32 7.90 9.48 II.06 12.6-l 14.22 IS.80 17.38 18.96
Flardoess, ERC max min 48 41 33 39 35 33 29 28 27 26 25 24
41 39 31 37 23 21
:::
Distance from quenched surface ‘/,a in. mm 13 I-l IS I6 18 20 22 2-l 26 28 30 32
20.54 22.12 23.70 25.28 28.44 31.60 33.76 31.92 41.08 44.24 47.40 SO.S6
Eardness, ARC max 2-l 23 23 22 21 21 21 20
4720, 4720H: Hardness vs Tempering Temperature. Represents an average
based
on a fully quenched
structure
and
Alloy Steel / 367
4720H: Hardenability
Curves. Heat-treating
(1700 “F). Austenitize:
925 “C (1700 “F)
Hardness wrposes I distance, nm 1.5
limits for specification Aardness, HRC Maximum Minimum 48 47 43 38 33 30 28 27 2-l 23 22 21 20
41 39 32 75 22 20
..
Hardness limits for specification xuposes I distance, 116in.
I 3 IQ II I2 13 1-I IS 16 18 !O !? !1 !6
Elardness, ERC Maximum Minimum 48 4-I 43 39 35 32 29 28 27 26 25 2-l 2-I 23 23 22 21 ‘I ?-I 20
41 39 31
27 23 21
temperatures
recommended
by SAE. Normalize (for forged or rolled specimens
only): 925 “C
1
366 / Heat Treater’s
Guide
4815,4815H Chemical
Composition.
4815. AIM and UNS: 0. I3 to 0. I8 C. 0.40
Annealing.
to0.60Mn,0.03SPmax.0.~0Smax.0.lSto0.30Si.3.35to3.7SNi.0.20 to 0.30 MO. UNS H-t8150 and SAE/AISI 4815H: 0. I2 to 0. I8 C. 0.30 to 0.70 hln. 0.15 to 0.35 Si. 3.20 to 3.80 Ni. 0.20 to 0.30 MO
After normalizing, heat to 650 ‘C (1200 “F), hold for I h per inch of section thickness. Cooling rate from this temperature is not critical. hlay also be isothermally annealed by heating to 745 “C (1370 “Fj. cooling rapidly to 605 “C (I I25 “F), and holding for 8 h
Similar
Tempering.
ASThl ASThl
Steels (U.S. and/or
Foreign).
4815.
A322. A33 I. ASOS: SAE J-IO-I. J-t I2.J770.4815I-l. A304 SAE J 1268
G48 I SO; UNS UNS H-18 I SO:
Characteristics. Represents a relatively high alloy carburizing grade intended for use where sections are thick and relatively hard. and tough cores are mandatory. Depending on the precise carbon content. asquenched hardness should be approximately: 35 to 42 HRC. Hardenability is relatively high. As is true for other htgh-nickel carburizing steels. austenite may be retained in the carburized case. Amenable to welding. but alloy steel practice of preheating and postheating must be used Forging. forging
Heat to 1245 “C 12275 “Ft. Do not forge after temperature stock drops below approxtmately 815 “C (15% “Ft
Recommended
Heat Treating
Practice
of
All parts made from this grade should he tempered at I50 “C (300 “F) or higher if some loss of hardness can be tolerated. Tempering ~bill help in transforming retained austenite
case Hardening. See carburizing process described for 31 l8H. This grade is rarely subjected to carbonmiding. Liquid carburizing. gas carburizing, and martempering are suitable processes
Recommended l l
Anneal
l
Rough and semifinish machine Case harden Temper Finish machine ccarburized parts only)
l
Heat to 925 “C (I695 “Fj. Cool in air
l
Sequence
Forge Normalize
l
l
Normalizing.
Processing
4815: Continuous Cooling Curves. Composition: 0.14 C. 0.45 Mn, 0.22 Si, 3.42 Ni, 0.21 MO. Austenitized at 925 “C (1695 “F). Grain size: 9. AC,, 800 “C (1475 “F); AC,, 730 “C (1350 “F). A: austenite, F: ferrite, B: bainite, M: martensite. Source: Bethlehem Steel
4815: Liquid Carburizing. Pinion liquid carburized at 900 “C (1650 “F) for 2.5 h. quenched in still oil, tempered at 205 “C (400 “F) for 0.5 h. Hardness, 58 to 60 HRC. 12 tests done to measure runout
Alloy Steel I369
4815: ZOIllZ
Carbon Gradients Temperature “F OC
4815: Isothermal Transformation
Atmosphere
Tiiein zone, h
Carbon potential, %,C
Cycle l(a) 1 2 3
1690 1690 1670
920 920 910
Methane Methane Carrier gas, air
8 14 13
1.25 1.25 0.80(b), 0.55(c)
Cycle 2(d) 1 2 3
1690 1690 1670
920 920 910
Methane Methane Carrier gas. air
6 10 9
1.25 1.25 0.80(b), 0.60(c)
Cycle 3(e) 1 2 3
1690 1690 1670
920 920 910
Methane Methane Carrier gas, air
4 7 6
1.25 1.25 0.80(b), 0.75(c)
Diagram. Carburized, 1 .O% carbon. Composition: 0.97 C, 0.52 Mn, 3.36 Ni, 0.19 MO. Austenitized at 980 “C (1795 “F). Grain size: 7
(a) Target, 0.1 IO-in. (2.79-mm) case at 0.25% C. (b) At center of fone. (c) At discharge. (d) Target, 0.~in. (2.29-mm) at 0.25% C. (e) Target. 0.070-m. (1.78-mm) case at 0.25% C
4815: Carbon Gradients. From three-zone
continuous pushertype carburizing furnace. Carbon potential was controlled manually. A: Cycle 1, 35 h; 0: Cycle 2, 25 h; 0: Cycle 3, 17 h
4815: End-Quench
Hardenability.
Mn, 3.36 Ni. 0.19 MO. Austenitized 8 to 9
Composition: 0.16 C, 0.52 at 900 “C (1650 “F). Grain size:
4815: End-Quench
Hardenability. Carburized, 1 .O% carbon. Composition: 0.97 C, 0.52 Mn, 3.36 Ni, 0.19 MO. Austenitized at 980 “C (1795 “F). Grain size: 7
4815, 4815H: Hardness vs Tempering Temperature. Represents an average based on a fully quenched structure
370 / Heat Treater’s
I 2 3 4 5 6 7 8 9 IO II I2
I .xX 3.16 4.74 6.32 7.90 9.48 I I .06 12.64 14.22 15.80 17.38 18.%
Guide
45 4-l 44 42 41 39 37 35 33 31 30 29
38 37 31 30 27 24 22 21 20
I3 l-l IS I6 I8 20 22 24 26 28 30 32
20.54 22.12 23.70 25.28 28.44 31.60 34.76 31.92 41.08 44.2-l 47.40 50.56
28 28 27 27 26 25 24 24 2-l 23 23 23
4815: Depth of Case vs lime and Temperature. 13 mm (0.5 in.) round bars, carburized at 900 “C (1650 “F), and oil quenched
4815: Variation in Carbon Concentration. Steel rock bit cutters carburized at 925 “C (1695 “F). Pit-type furnace, 314 mm (36 in.) in diameter by 1829 mm (72 in.) deep, used a carburizing-diffusion cycle. Dew point controlled at the generator only. Each test represents one load of 1361 kg (3000 lb). (a) 40 tests. Carbon at 1.8 mm (0.070 in.) below surface; (b) 50 tests. Carbon at 2.42 mm (0.095 in.) below surface
4815: Isothermal Transformation Diagram. Composition: 0.16 C, 0.52 Mn. 3.36 Ni, 0.19 MO. Austenitized at 900 “C (1650 “F). Grain size: 8 to 9
4815: Variation of Surface Carbon Content. 50 tests of rock bit cutters carburized in two pit-type furnaces to an aim of 0.75% C. Furnaces were operated simultaneously, using the same gas generator. Each furnace was 914 mm (36 in.) in diameter by 1829 mm (72 in.) deep and contained a load of about 1361 kg (3000 lb). A carburize-diffuse cycle was used. An automatic dew point controller was employed on the generator, but not on the furnace
Alloy Steel / 371
4815H: CCT Diagram. Composition
for commercial SAE 4815 carburizing steel: 0.16 C, 0.63 Mn, 0.010 P, 0.012 S, 0.24 Si, 3.35 Ni, 0.21 Cr, 0.24 MO. 0.19 Cu. In this study, slabs from commercial billet 76 mm (3 in.) square were normalized at 925 “C (1695 “F) for 1 h. Specimens were austenitized at 870 “C (1600 “F) for 20 min. The purpose of the study was to characterize a standard grade of carburizing steel for comparison with recently developed grades. Source: Datasheet l-257. Climax Molybdenum Company
372 / Heat Treater’s
Guide
4815H: Hardenability (1700 “F). Austenitize:
Hardness purposes J distance, IUDI 1.5
II 13 .5 !O Y IO i5 lo 15 ;0
Curves. Heat-treating 845 “C (1555 “F)
limits for specification Eardness, HRC Maximum Minimum 45 45 44 42 40 31 35 32 29 27 26 25 24 24 23
38 36 33 28 25 22 20
.
. .. .
iardness wrposes
limits for specification
I distance, 116in.
Eardnes, Maximum
I
, 1
IO I1 12 13 14 15 I6 8 !O !2 !4 !6 !8 IO I2
45 44 44 42 41 39 37 35 33 31 30 29 28 28 21 27 26 25 24 24 24 23 23 23
ARC hlinimum 38 31 34 30 27 24 22 21 20 ..”
.
temperatures
recommended
by SAE. Normalize (for forged or rolled specimens
only): 925 “C
Alloy Steel / 373
4817,4817H Chemical
Composition.
4817. AISI and UNS: 0. IS to 0.20 C. 0.40
Annealing.
to0.60hln.0.03SPmax.0.~0Smax.0.lSto0.30Si.3.1Sto3.7SNi.0.20 to 0.30 MO. UNS A18170 and SAE/AISI 4817H: 0. II to 0.20 C. 0.30 to 0.70 hln. 0.1s to 0.35 Si. 3.20 to 3.80 Ni. 0.20 to 0.30 hlo
After normnlizinp. heat IO 650 “C (I100 “F), hold for I h per inch of section thickness. Cooling rnte from this temperature is not critical. hIa> also be isothermall> annealed b> heating to 715 “C (I 370 “F), cooling rapidly to 605 “C ( I I25 “F). and holding for 8 h
Similar
Tempering.
ASTM ASTM
Steels (U.S. and/or A3X. A304
Foreign).
4817.
A33 I. AS 19; SAE J-104. J-l I?. 5770.4817H. SAE Jl368
UNS G-18170: UNS H-I8 170:
Characteristics. U’ith the exception of a slightly higher carbon content, steels 18lSH and 1817H we identical. and thiir characteristics me essentially identical. As-quenched hardness (core hardness) should be slightI> higher for 1817H (approximately 36 to 43 HRC). Hardcnahilit!, patterns are nearly identical. Welding is possible. but preheating and postheating must be used Forging.
Heat to 12-15 “C (2175 OF) mnsimum. Do not forge after temperature of forging stock drops belo\{ approxunatel> 8-U “C ( IS55 “F)
Recommended Normalizing.
Case Hardening. See cttrhurizinp process described grade is rareI> subjected to carhonitriding
Recommended l l l l
Practice
l
“FL Cool in air
l
Heat Treating
Heat to 925 “C (16%
All pans made from this grade should he tempered at IS0 “C (300 “F) or higher if some loss of hrudness GUI be talented. Tempering \\ill help in transtormma retnmed wstenite
l
Processing
for 41 l8H. This
Sequence
Forge Normalize Anneal Rough md semifinish machine Case harden Temper Finish machine (cluburized parts only)
4817H: End-Quench Hardenability Distance from quenched surface I/lb in. mm
Hardness, HRC min max
Distance from quenched surface ‘lib in. mm
Hardness, HRC mas
I 7
I 58
46
39
13
20.5-i
30
; -I 5 6 7 8 9 10 II I2
-1.7-l 3.16 6.32 7.90 9.18 I I.06 I2.M I-I.72 IS.80 17.38 18.96
45 46 44 12 -II 39 37 35 33 3’ Iii
3x 35 32. ‘9 27 1.5 23 22 21 20 ‘0
I-l 15 16 18 70 22 24 ‘6 ‘8 30 32
22.12 13.70 25.x3 ‘8.44 31.60 34.76 37.91 41.08 44.2-l 47.40 SO.56
‘9 ‘8 78 17 26 3 25 25 2.5 2-l 21
4817, 4817H: Hardness vs Tempering Temperature. Represents an average
based
on a fully quenched
structure
374 / Heat Treater’s
Guide
4817: Carburizing
and Hardening vs Diametral Dimensions. Bevel drive pinion gear (a), carburized at 925 “C (1695 “F), tempered at 160 “C (320 “F). Depth of case, 1.27 to 1.65 mm (0.050 to 0.065 in.). Major spline diameter of twenty-five 4 kg (8 lb) gears (b) before treatment, (c) after treatment
4817: Cooling Curve. Half cooling time. Source: Datasheet
I-50. Climax Molybdenum
Company
Alloy Steel / 375
4817: CCT Diagram. Chemical composition:
0.17 C, 0.54 Mn, 0.015 P, 0.025 S, 0.33 Si, 0.087 Al. Alaboratory induction air melted heat. Specimens 4 mm (0.16 in.) in diameter were through-catburized to various carbon levels by holding in a carburizing atmosphere at 1150 “C (2100 “F) for 16 to 20 h. Machined dilatometer specimens 3 mm ((0.118 in.) in diameter were austenitized and cooled at three different rates to define the partial CCT diagram at each carbon level. The cooling rates ranged from 375 to 3280 “C (675 to 5900 “F) per min. The cooling curves used to define the diagrams are not shown. Instead, the cooling curves shown were measured on impact-fracture specimens (gear tooth simulation) at locations corresponding to the surface and the case-core interface during quenching in warm oil 66 “C (150 “F) or in hot oil 170 “C (340 “F). Specimens were austenitized at 900 “C (1650 “F) for 20 min. The objectives of the study were to obtain partial kinetic data on continuous-cooling transformation at various carbon levels in the carburized case. Hardness values (in circles on the diagram) were exhibited by specimens of each carbon level subjected to the fastest cooling rate used to define each CCT diagram. Source: Datasheet 1279. Climax Molybdenum Company
(continued)
376 / Heat Treater’s
Guide
4617: CCT Diagram. (continued)
Alloy Steel / 377
4817H: Hardenability
Curves. Heat-treating
(1700 “F). Austenitize:
845 “C (1555 “F)
iardness wrposes I distance, nm 1.5
3 I1 13 I5 !O 5 30 3.5 lo 15 50
iardness wrposes distance, :I6 in. I 2 3 1 5 5 7 9 1 10 11 12 13 14 15 16 18 20 22 24 26 28 30 32
limits for specification Eardness, Maximum
HRC hlinimum 39 38 35 31 28 25 23 21
46 46 45 44 42 39 37 34 31 28 21 26 25 25 25
... .
limits for specification Hardness, Maximum 46 46 45 44 42 41 39 37 35 33 32 31 30 29 28 28 27 26 25 25 25 25 24 24
HRC hfinimum 39 38 35 32 29 27 25 23 22 21 20 20
. . .
. .
temperatures
recommended
by SAE. Normalize (for forged or rolled specimens
only): 925 “C
378 / Heat Treater’s
Guide
4820,4820H,
4820RH
Chemical COIIIpOSitiOn. 4820. AISI and UNS: 0.18 to 0.23 C. 0.50 to0.70Mn.0.035Pmax.0.040Smax.0.15to0.30Si,3.25to3.75Ni.0.20 to 0.30 MO. UNS H48200 and SAE/AISI 48208: 0. I7 to 0.23 C. 0.40 to 0.80 Mn. 0.15 to 0.35 Si, 3.20 to 3.80 Ni. 0.20 to 0.30 MO. SAE IZORH: 0.18 to 0.23 C, 0.50 to 0.70 Mn. 0.15 to 0.35 Si. 3.25 to 3.75 Ni, 0.20 to
Recommended Normalizing.
Heat Treating
Practice
Heat to 925 “C (I 695 “F). Cool in air
Annealing.
0.30 MO
After normalizing, heat to 650 “C (I 200 “F). hold for I h per inch of section thickness. Cooling rate from this temperature is not critical. hlay also be isothermally annealed by heating to 745 “C ( I370 “F). cooling rapidly to 605 “C ( I I25 “F), and holding for 8 h
Similar
Tempering.
Characteristics.
Case Hardening. See carburizing process described grade is rarely subjected to carbonitriding. Austempering process
G-18200; Steels (U.S. and/or Foreign). 4820. UNS ASTM A322, A33 1, A505. AS 19, A535; SAE JW. 5412. J770. 4820H. UNS H48200; ASTM A304, A9 14; SAE J I 268. J8668
In general. the characteristics of 4820H are similar to those described for 48 I SH and 48 17H. Because of higher carbon content. as-quenched hardness of 4820H ranges from approximately 40 to 45 HRC. The hardenability band is shifted upward when compared with the bands for 4815H and 4817H. As is true for other high-nickel carburizing steels. there is a strong tendency for retention of austenite in the carburized cases of 4820 and 4820H. Amenable to welding, but alloy steel practice of preheating and postheating must be used
Forging. temperature
Heat to 1245 “C (2275 “Fj maximum. Do not forge after of forging stock drops below approximately 845 “C (I 555 “F)
Carburizing,
4820:
All parts made from this grade should be tempered at 150 “C (300 “F) or higher if some loss of hardness can be tolerated. Tempering will help in transforming retained austenite
Recommended
Processing
for 4118H. This is an alternative
Sequence
Forge Normalize . Anneal l Rough and semifinish machine l Case harden l Temper l Finish machine (carburized parts only) l l
Single Heat Results
Specimens contained 0.21 C, 0.51 Mn, 0.021 P, 0.018 S, 0.21 Si, 3.49 Ni, 0.18 Cr. 0.24 MO; critical points 1440 “F (780 “C); Ar,, 1215 “F (855 “C); Ar,, 780 “F (415 “C); grain size was 6 to 8; 0.565-in. (14.4-mm) round tested Yield strength 0.2% offset ksi hU’a
Ctl.92 Recommended practice
Eardness, ARC
Depth in.
mm
..,
For maximum case hardness Direct quench 6om pot(a) Single quench and temper(h) Double quench and temper(c)
60 61 60
0.039 0.047 0.047
For maximum core toughness Direct quench from pot(d) Single quench and temper(e) Double quench and tempertf)
56 57.5 56.5
0.039 0.047 0.047
included AC,, 1310 “F (710 “C); AC,, round treated. 0.505-in. (12.8-mm)
Tensile strength hIPa ksi
Elongation Reduction in2ill. Ofare& (50mm), % %
Hardness, EB
205 2075 204.5
l-11) 1431 1110
165.5 167 I65 5
II-II II51 II-11
13.3 I38 13.8
53.3 52.2 52.4
41.5 415 415
200.5 205 196.5
I382 1113 I355
170 184.5 171.5
II72 1272 I I82
12.8 13.0 13.0
53.0 53.3 53.4
4QI 41s 401
(a)Carburized at 1700 “F(92S “C) for 8 h, quenched in agitated oil. tempered at 3OO”F( IS0 “C, (h) Catknzed at 17OO”Ft925 “CI for 8 h. pot cooled. reheated to 1475 “F(800 “C). quenched in agitated oil. tempered at 300 “F (IS0 “C). Good case and core properties. (5) Carburized at I700 “F t92S “C) for 8 h. pot cooled. reheated to IS00 “F (815 “C). quenched inagitatedoil. reheated to IJSO”F(79O”C). quenched inagitatedoil. temperedat 3OO”F(lSO”C). For maximum refinement ofcaseandcore. (d)Carburizedat 1700°F (925”C)forS h.quenched inagitatedoil, temperedat450”F(230°C). te)Carhurizedat 1700”F(92S°C) for8 h. potcooled. reheated to lJ7S”F(800°C).quenched inagitatedoil. tempered at 450”F(230”C). Goodcaseandcore properties. (nCarburizedat 17OO”F(925 “0 for8 h. pot cooled. reheated IO 1500°F~81S “C).quenched in agitatedoil. reheated to 1~50”F~7’H)“C~,quenchedinagitatedoil.temperedat~50”F~230”C).(Source: BethlehemSteel)
4820:
As-Quenched
Hardness
(Oil)
4820: Hardness vs Tempering Temperature.
Grade: 0.18 to 0.23 C, 0.50 to 0.70 Mn. 0.20 to 0.35 Si, 3.25 to 3.75 Ni.0.20to0.30Mo;ladle:0.20C,0.61 Mn,0.027P,0.016S,0.29Si, 3.47 Ni, 0.07 Cr, 0.22 MO; grain size: 6 to 8 Si
round
in.
mm
Surface
Rardness, HRC ‘12radius
Cenler
‘/I
I3 15 51 102
45 4s 36 27
4.5 39 31 21
4-l 37 27 24
I 2 4
Source: Bethlehem Steel
average
based
on a fully quenched
structure
Represents
an
Alloy Steel I379
4820: Variation of Surface Carbon Content after Carburizing. Surface carbon concentration [first 0.076 mm (0.003 in.) depth of cut] in nineteen 25.4 mm (1 in.) diam bars carburized with production parts in a two-row continuous furnace. Desired carbon content, 0.75 to 0.80%. Specimens were carburized at 925 “C (1695 “F) using a diffusion cycle, quenched from 815 “C (1500 “F) in oil at 60 “C (140 “F), tempered in lead at 620 “C (1150 “F) for 5 min, wire brushed, and liquid-abrasive cleaned. Atmosphere at the charge end of the furnace was automatically controlled at a dew point of -15 “C (5 “F) and at the discharge end at 3 “C (35 “F). Endothermic gas enriched with straight natural gas was used as the carbunking medium; air was added at the discharge end
4820H: End-Quench Hardenability Distance from quenched surface ‘/,b in. mm
Eardness, ERC max min
Distance 6om quenched surface
‘46in.
,IM,l
2 3
1.58
3.16 4.74
48 48 47
41 40 39
13 I4 1s
-I 5 6 7
6.32 7.90 9.48 I I.06
46 45 43 32
38 3-l 31 ‘9
16 18 20 22
20.54 22.12 23.70 2S.28 28.44 31.60 34.76
8 9 IO II I2
12.64 14.22 IS.80 17.38 18.96
-IO 39 37 36 35
27 26 25 2-l 23
24 26 28 30 32
37.92 41.08 44.24 47.40 50.56
I
Rardoess, ERC max min 34 33 32 31 29 28 28 27 27 26 26 25
22 22 ?I ‘I 20 20 ..,
.._ .._ .__
380 / Heat Treater’s
4820: Continuous Austenitized
Guide
Cooling Transformation
0.18 C, 0.47 Mn, 0.009 P, 0.010 S, 0.27 Si, 3.33 Ni, 0.18 Cr, 0.23 MO. at 900 to 920 “C (1650 to 1690 “F) for 4 h
Diagram. Composition:
at 780 “C (1435 “F). Blank carburized
Alloy Steel I381
4820H: Hardenability
Curves. Heat-treating
(1700 “F). Austenitize:
845 “C (1555 “F)
Hardness purposes J distance, mm 1.5 3 5 I 9 11 13 15 20 25 30 35 40 4.5 50
Hardness purposes I distance, k,b in. 1 2 3 1 5 5 7 B 9 10 11 12 13 14 15 16 18 20 22 24 26 28 30 32
limits for specification Hardness, hlaximum
HRC hlinimum 41 40 39 36 32 29 27 25 22 21 20 .
48 48 48 46 45 43 40 39 3.5 32 29 28 21 26 26
limits for specification Hardness, hlarimum 48 48 41 46 45 43 42 40 39 37 36 35 34 33 32 31 29 28 28 21 21 26 26 25
HRC hlinimum 41 40 39 38 34 31 29 21 26 25 24 23 22 22 21 21 20 20
. . ..
temperatures
recommended
by SAE. Normalize (for forged or rolled specimens
only): 925 “C
1
382 / Heat Treater’s
Guide
4820RH: Hardenability “C (1700 “F). Austenitize:
Hardness purposes J distance, ‘46io.
I 2 3 4 5 6 7 B
9 IO II 12 13 II IS I6 I8 ?O 12 2-l 16 18 30 32
Hardness purposes J distance,
mm I .5 3 s 7
9 II 13 IS 20 !5 30 35 40 85 SO
Curves. Heat-treating 845 “C (1555 “F)
limits for specification Eardoes, Maximum
ARC Minimum
17 47 46 45 33 41 40 38 36 35 34 33 32 31 30 29 28 27 26 25 25 25 24 23
42 32 -II xl 36 33 32 30 28 27 26 25 24 24 23 33 22 22 21 20 20
limits for specification Hardness, HRC Minimum Maximum 37 47 46 44 42 40 38 3.5 32 29 27 26 25 24 23
12 42 31 38 3-l 32 30 27 2-l 23 22 21 20
temperatures
recommended
by SAE. Normalize
(for forged or rolled specimens
only): 925
1
Alloy Steel / 383
50940,50940H,
50940RH
Chemical Composition. 5OB40. AISI: 0.38 to 0.43 C, 0.75 to I .oo Mn, 0.035 P max. 0.040 S max. 0.40 to 0.60 Cr. 0.0005 B min. UNS: 0.38 to 0.42 C, 0.75 to I .OO Mn, 0.035 P max. 0.040 S max. 0. I5 to 0.30 Si. 0.10 to 0.60 Cr. 0.0005 B min. UNS A50401 and SAE/AISI 50B40H: 0.37 to 0.1WC.0.65to1.10Mn.0.15to0.35Si.0.30to0.70Cr.B(c~beexpected to be 0.0005 to 0.003 percent). SAE SOB4ORH: 0.38 to 0.43 C. 0.75 to I .OO Mn. 0.15 to 0.35 Si, 0.40 to 0.60 Cr. B (can be expected to be 0.0005 to 0.003 percent) Similar Steels (U.S. and/or Foreign).
50B40. UNS G5w01; ASTM A5 19; SAEJ404.5412, J770; (Ger.) DIN 1.7007; (Ital.) UN1 38 CrB I KB. 50B40H. UNS H50401; ASTM A304, A914: SAE Jl268. Jl868; (Ger.) DW I .7007: (Ital.) UN1 38 CrB I KB
Characteristics. A medium-carbon gade with an as-quenched surface hardness in the range of approximately 52 to 58 HRC. depending on whether the carbon is low or high on the allowable range. The hardenability band for SOB-IOH is nearly equal to that of 8630H. a higher alloy and more expensive steel. Is easily foged and responds readily to heat treatments that are used for other low-alloy steels of similar carbon content
Annealing.
For a predominately pearlitic structure, heat to 830 “C (1525 “F), cool rapidly to 740 “C ( I365 “F), then to 670 “C ( 1240 “F) at a rate not to exceed I I “C (20 “F) per h: or heat to 830 “C (I 525 “F). cool rapidly to 675 “C (1245 “R. and hold for 6 h. For a predominately spheroidized structure. heat to 760 “C (I 300 “F), cool to 665 “C ( I230 “F) at a rate not to exceed 6 “C ( IO “F) per h; or heat to 760 “C ( 1400 “F), cool rapidly to 665 “C (1230 “F). and hold for 8 h. For most subsequent operations such as machining and hardening, a predominately spheroidized structure is preferred
Hardening. Tempering.
Heat to 1230 “C (3250 “FI maximum. Do not forge after temperature of forging stock drops below approximately 925 “C ( I695 “F)
Recommended l l l
Recommended
Heat Treating
Practice
l l
Normalizing.
Heat to 870 “C ( I600 “F). Cool in air
5084OH: End-Quench Distance from quenched surface l/16 in. mm I 2 3 4 5 6 7 8 9 IO II I?
I .58 3.16 1.7-l 6.32 790 9.48 I I.06 12.64 14.22 15.80 17.38 18.96
Eardness, ARC mar min 60 60 59 59 58 58 57 57 56 55 53 51
l
Hardenability
53 53 52 51 50 48 4-l 39 31 31 29 28
Distance from quenched surface ‘/la in. mm 13 1-l 15 I6 ia 20 22 2-l 26 28 30 32
20.51 22.12 23.70 25.28 28.4-I 31.60 31.76 31.92 41.08 44.2-l 47.40 50.56
Aardness. HRC min max 19 47 4-l 31 38 36 35 34 33 32 30 29
27 26 25 25 23 II
at 845 “C (1555 “F). and quench in oil
Parts made from SOB-tOH should be tempered immediately after they have been uniformly quenched to near ambient temperature. Best practice is to place workpieces into the tempering furnace just before they have reached room temperature. ideally when they are in the range of 38 to 50 “C (100 to I20 “F). Tempering temperature must be selected based upon the tinal desired hardness
l
Forging.
Austenitize
Processing
Sequence
Forge Normalize Anneal Rough and semifinish machine Austenitize and quench in oil Temper Finish machine
50840,50B40H:
Hardness
sents an average
based
vs Tempering
on a fully quenched
Temperature. structure
Repre-
384 / Heat Treater’s
Guide
50940H: Hardenability
Curves. Heat-treating
“C (1600 “F). Austenitize:
845 “C (1555 “F)
Hardness purposes J distance, mm 1.5 3 5 7 9 11 13 15 20 25 30 35 40 45 50
Hardness purposes J distance, ‘/,6 in. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 18 20 22 24 26 28 30 32
limits for specification Eardness, Maximum
ARC Minimum
60 60 60 59 59 58 57 56 50 43 37 35 34 32 30
53 53 52 51 49 44 38 33 27 24 22
limits for specification Eardness, Maximum 60 60 59 59 58 58 57 57 56 55 53 51 49 47 44 41 38 36 35 34 33 32 30 29
RRC blinimum 53 53 52 51 50 48 44 39 34 31 29 28 27 26 25 25 23 21
temperatures
recommended
by SAE. Normalize
(for forged or rolled specimens
only): 870
Alloy Steel / 385
50B40RH: Hardenability Curves. Heat-treating temperatures “C (1600 “F). Austenitize:
845 “C (1555 “F)
iardness limits for specification wrposes I distance, /lfJ in.
0
Hardness, ARC Maximum Minimum 59 59 58 58 57 56 55 5-l 52. so -t9 47 -is 4.4 -II 38 36 3-t 33 37 31 30
5-l 5-I S? S3 52 SO -17 13 38 35 33 3’ ii 30 ‘9 28 26 2-l 23 21 21 20
19 28
iardness limits for specification wrposes distance, mm
.s
Rardness, EIRC hlinimum Maximum S-l 5-l 53 s3
3
59 59 58 98 56 55 5-l
5
51
0
46
5 5
39 35 33
36 31 ‘8 3 23
0
31
?I
5
29 28
20
I
(I
0
51 47 42
recommended
by SAE. Normalize (for forged or rolled specimens
only): 870
386 / Heat Treater’s Guide
50844,50B44H Chemical Composition.
5OB44. AIM: 0.43 to O.-i8 C. 0.75 to 1.OO
Mn. 0.035 P max. 0.040 S max. 0. I5 to 0.30 Si, 0.40 to 0.60 Cr. 0.0005 to 0.003 B. IJNS: 0.43 to 0.48 C. 0.75 to 1.00 Mn, 0.035 Pmax. 0.040 S max, 0.15 to 0.30 Si. 0.40 to 0.60 Cr. 0.0005 B min. UNS ES0441 and SAE/AISI 50B44H: 0.42 to 0.49 C. 0.65 to I. IO Mn. 0. I5 to 0.35 Si. 0.30 to 0.70 Cr. B (can be expected to be 0.0005 to 0.003 percent)
Similar Steels (U.S. and/or Foreign). SoB44. ASTM A5 19; SAE 5404, 5412. 5770. 50B44H. A304; SAE J I268
UNS Gs04-1 I ; UNS H50441; ASTM
Characteristics. Has the same general characteristics as 50B40H. Because of slightly higher carbon content, the as-quenched hardness of SOB44H will be higher. although the carbon ranges of the two steels overlap. The asquenched hardness will range from approximately 54 to 60 HRC. Hardenability bands for the two grades are similar. the band for SOB44H shifted slightly upward. Is easily forged and responds readily to heat treatments that are used for other low-alloy steels of similar carbon content
Annealing.
For a predominately pearlitic structure, heat to 830 “C (I 525 “F), cool rapidly to 740 “C (I 365 OF). then to 670 “C ( 1240 “F) at a rate not to exceed I I “C (20 “F) per h: or heat to 830 “C (I 525 “F), cool rapidly to 675 “C (I235 “F). and hold for 6 h. For a predominately spheroidized structure. heat to 760 ‘C ( 1300 “F), cool to 665 “C ( I230 OF) at a rate not to exceed 6 “C (IO “F) per h: or heat to 760 “C (1400 “F), cool rapidly to 665 “C ( 1230 “F). and hold for 8 h. For most subsequent operations such as machining and hardening, a predominately spheroidized structure is preferred
Hardening. Tempering.
Heat to 1230 “C (2250 “F) maximum. Do not forge after temperature of forging stock drops below approximately 925 “C (1695 “F)
Recommended
Heat Treating
Practice
Recommended l
Anneal
Rough and semifinish machine Austenitire and quench in oil Temper Finish machine
l
Sequence
Forge Normalize
l l
Heat to 870 “C (1600 “Fj. Cool in air
Processing
l
l
Normalizing.
at 845 “C (IS55 “F), and quench in oil
Parts made from SOB34H should be tempered immediately after they have been uniformly quenched to near ambient temperature. Best practice IS to place workpieces into the tempering furnace just before they have reached room temperature, ideally when they are in the range of 38 to 50 “C ( IO0 to I20 “F). Tempering temperature must be selected based upon the final desired hardness
l
Forging.
Austenitize
50844,50844H:
Hardness vs Tempering Temperature. Repre-
sents an average based on a fully quenched structure
50844H: End-Quench Hardenability Distancefrom Eardoess, ERC min max I 2 3 4 5 6 7 8 Y IO II 12
I.58 3.16 4.74 6.32 7.90 9.48 Il.06 12.64 I-I.22 IS.80 17.38 I a.96
63 63 62 62 61 61 60 60 59 58 57 56
56 56 55 55 54 52 48 43 38 34 31 30
Distance from quenched surface Vi6 in. mm I3 I-2 IS I6 IX 20 ‘2 24 26 28 30 32
20.54 22. I2 23.70 25.28 28.4-I 31.60 34.76 37.92 11.08 44.2-l 47.-Kl 50.56
EZUdlleSS,
ERC max
min
5-l 52 SO 48 44 -lo 38 37 36 35 3-l 33
29 29 28 27 26 2-l 23 21 20
Alloy Steel / 387
50844H: Hardenability
Curves. Heat-treating
“C (1600 “F). Austenitiie:
845 “C (1555 “F)
iardness wrposes I distance. qm
1.5 3 5 7 ?
I1 13 15 20 25 30 35 10 15 50
iardness wrposes distance,
‘16in.
1 3 IO I1 12 13 I4 I5 I6 I8 !O !2 !4 !6 !8 SO i2
limits for specification Hardness, ERC Maximum Minimum 63 63 63 62 61 61 60 59 55 49 42 38 31 35 34
56 56 55 54 52 49 42 36 30 21 25 23 21
.
limits for specification Eardness, HRC Maximum Minimum 63 63 62 62 61 61 60 60 59 58 51 56 54 52 50 48 44 40 38 37 36 35 34 33
56 56 55 55 54 52 48 43 38 34 31 30 29 29 28 27 26 24 23 21 20
.
temperatures
recommended
by SAE. Normalize
(for forged or rolled specimens
only): 870
1
388 / Heat Treater’s Guide
5046,5046H Chemical Composition.
Annealing. For a predominately pearlitic structure, heat to 830 “C (1525
Similar Steels (U.S.
OF), cool rapidly to 755 “C (1390 “F), then cool from 755 “C (1390 “F) to 655 “C (1220 “P) at a rate not to exceed 11 “C (20 “F) per h; or heat to 830 “C (1525 “F), cool rapidly to 665 “C (1230 OF), and hold for 4 qz h. For a predominately spheroidized structure, heat to 760 “C (1400 OF),cool to 665 “C (1230 “F) at a rate not to exceed 6 “C (10 “F) per h; or heat to 760 “C (1400 “F), cool rapidly to 660 “C (1220 “F), and hold for 8 h
5046. AISI: 0.43 to 0.50 C, 0.75 to 1.00 Mn,0.040Pmax,O.O40S max.0.20to0.35 Si,O.20 too.35 Cr. UNS: 0.43 to0.50C,0.75to1.00Mn,0.035Pmax,0.040Smax,0.15to0.30Si,0.20 to 0.35 Cr. UNS I-I50460and SAE/AISI 5046lk0.43 to 0.5OC,O.65 to 1.10 Mn, 0.15 to 0.35 Si, 0.13 to 0.43 Cr and/Or
Foreign). 5046.
ASTM A519; SAE J404,J412,J770.5046H. SAE J 1268
UNS G50460; UNS H50460; ASTM A304:
Characteristics.
A typical medium-carbon, very low-alloy steel. When both manganese and chromium are on the high side of their allowable ranges, 5046H has sufficient hardenability so that full hardness can be obtained in thin sections by oil quenching. As-quenched hardness typically ranges from approximately 53 to 58 HRC, depending on whether the carbon is on the low or the high side of the range
Hardening. Austenitize at 845 “C (1555 “F), and quench in oil for thin sections. Thicker sections wih require a water or brine quench for full hardness Tempering. After quenching, reheat to the temperature required to achieve the final desired hardness
Recommended
Processing
Sequence
Forge l Normalize l Anneal (preferably spheroidize) l Rough machine l Harden Q Temper l Finish machine l
Forging. Heat to 1230 “C (2250 “F) maximum. Do not forge after temperature of forging stock drops below approximately 870 “C (1600 “F)
Recommended
Heat Treating
Practice
Normalizing. Heat to 870 “C (1600 “F). Cool in air
5046: Hardness vs Tempering Temperature. Normalized at 870
5046H: End-Quench Hardenability
“C (1600 “F), quenched from 845 “C (1555 “F), tempered in 56 “C (100 “F) intervals in 13.7 mm (0.540 in.) rounds. Tested in 12.8 mm (0.505 in.) rounds. Source:.Republic.Steel
Distance from quenched surface
&h.
mm
1
1.58 3.16 4.15 6.32 7.90 9.48 1.06 12.64 14.22 15.80 17.38 18.96
2 3 4 5 6 I 8 9 10 11 12
Hardness, HRC max min 63 62 60 56 52 46 39 35 34 33 33 32
56 55 45 32 28 27 26 25 24 24 23 23
Distance from quenched surface
?,&h.
mm
13 14 15 16 18 20 22 24 26 28 30 32
20.54 22.12 23.70 25.28 28.44 31.60 34.76 37.92 41.08 44.24 47.40 50.56
Hardness, HRC max min 32 31 31 30 29 28 27 26 25 24 23 23
22 22 21 21 20
Alloy
5046H: Hardenability (1600 “F). Austenitize:
Hardness purposes J distance. mm 1.5
3 5 7 9 11
13 15
20 25 30 35 40 45
Hardness purposes I distance, %6 in.
0 1
2 3 4 5 6 8 0 2 4 6 8 0
Curves. Heat-treating 845 “C (1555 “F)
limits for specification flardness, HRC Maximum hIinimum 63 62 59 54 48 39 35 34 32 30 29 27 26 24
56 54 40 30 27 26 25 25 22 20 .
limits for specification Hardness, HRC Maximum hlinimum 63 62 60 56 52 46 39 35 34 33 33 32 32 31 31 30 29 28 21 26 25 24 23
56 55 45 32 28 21 26 25 24 24 23 23 22 22 21 21 20 ..” ...
temperatures
recommended
by SAE. Normalize (for forged or rolled specimens
Steel / 389
only): 870 “C
390 / Heat Treater’s Guide
50B46,50B46H Chemical Composition.
SOB46. AISI: 0.44 to 0.49 C, 0.75 to 1.OO Mn, 0.035 P max. 0.040 S max. 0. I5 to 0.30 Si, 0.20 to 0.35 Cr. 0.0005 to 0.003 B. UNS: 0.44 to 0.49 C, 0.75 to 1.00 Mn. 0.035 Pmax. 0.040 S max. 0.15 to 0.30 Si. 0.20 to 0.35 Cr. 0.0005 B min. UNS II50461 and SAE/AISI SOB46H: 0.43 to 0.50 C. 0.65 to I. 10 Mn, 0.15 to 0.35 Si. 0.13 to 0.43 Cr. B (can be expected to be 0.0005 to 0.003 percent)
Similar Steels (U.S. and/or Foreign).
SOB46. IJNS G5046I ; ASTM ASTM A519; SAE J404. 5412, J770. 50B46H. UNS H5046I: A304; SAE J I268
Characteristics. Boron influences 50B36H much the same as it affects 50B4OH and 50B44H. 50B46H has a lower chromium content. When the chromium is low. approaching 0.13. the hardenability without the boron would be little more than that of a plain carbon steel. Hardenability is lower when compared with 50BUH. As-quenched surface hardness for 50B46H can be expected to be about the same as for 50B44H. 54 to 60 HRC Forging. temperature
Annealing.
For a predominately pearlitic structure. heat to 830 “C (1525 “F), cool rapidly to 740 “C ( I365 OF). then cool to 670 “C (1240 “F) at a rate not to exceed I I “C (20 “F) per h; or heat to 830 “C (I 525 “F), cool rapidly to 675 “C (I 245 “F), and hold for 6 h. For a predominately spheroidized structure, heat to 760 “C ( 1400 “F’), cool to 665 “C ( 1230 “F) at a rate not to exceed 6 “C (IO “F) per h: or heat to 760 “C ( 1400 “F), cool rapidly to 665 “C (I230 “F), and hold for 8 h
Hardening. Tempering.
Recommended l l l
Recommended
Heat Treating
Practice
l l
Normalizing.
Heat to 870 “C (1600 “F). Cool in air
50646: Hardness vs Tempering Temperature. Normalized
l
at
870 “C (1600 “F), quenched from 845 “C (1555 “F) in oil and tempered in 56 “C (100 “F) intervals in 13.7 mm (0.540 in.) rounds.
Tested in 12.8 mm (0.505 in.) rounds. Source: Republic Steel
at 845 “C (I 555 “F), and quench in oil
Parts made from 50B44H should be tempered immediately after they have been uniformly quenched to near ambient temperature. Best practice is to place workpieces into the tempering furnace just before they have reached room temperature. ideally when they are in the range of 38 to 50 “C ( 100 to I20 “F). Tempering temperature must be selected based upon the final desired hardness
l
Heat to 1230 “C (2250 “F) maximum. Do not forge after of forging stock drops below approximately 925 “C (1695 “F)
Austenitize
Processing
Sequence
Forge Normalize Anneal Rough and semifinish machine Austenitize and quench in oil Temper Finish machine
50846H: End-Quench Hardenability Distance from quenched surface V,6 in. mm I 2 3 .I 5 6 7 8 9 IO II I2
1.58 3.16 1.74 6.32 7.90 9.48 II.06 12.6-l 14.21 15.80 17.38 18.96
Hardness. BRC min may 63 62 61 60 59 58 57 56 54 51 17 13
56 5-l 52 so -II 32 31 30 29 28 27 26
Distance from quenched surface 916in. mm 13 I-I IS 16 I8 ‘0 22 2-l 26 28 30 32
20.54 22.12 23.70 25.28 28.4-I 31.60 34.76 37.92 II .08 44.2-l 47.40 50.56
Eardoess, ERC msx min 40 38 37 36 35 34 33 32 31 30 29 28
26 25 25 23 23 22 21 20
_..
Alloy Steel / 391
50B46H: Hardenability Curves. Heat-treating temperatures recommended by SAE. Normalize (for forged or rolled specimens only): 870°C (1600 “F). Austenitize: 845 “C (1555 “F)
Hardness limits for specification wrposes I distance, nm
Eardness, ERC luaximum Minimum 63 62 61
56
60
47
59 58 56 53 12 37 35
35 31 29 ‘8 76
34
55 53
24 22 21
32 31 29
iardness limits for specification wrposes I distance,
46i”.
, I ,
I I 0 I 2 3 4
5 6 8
II ‘2 4 6 8
‘0 ‘2
Eardoess, ERC Maximum Minimum 63 62 61
60 59 58 51 56 54
51 47 43
40 38 31 36 35 34 33 32 31 30 29 28
56 54
52 50 41 32 31
30 29 28
27 26 26
25 25 2-l 23 22
II 20
392 / Heat Treater’s
Guide
50B50,50B50H Chemical
COIIIpOSitiOn. 50B50.AISI: 0.48 to 0.53 C. 0.75 to 1.00 Mn. 0.035 P max. O.MO S max. 0. IS to 0.30 Si, O.-IO to 0.60 Cr. 0.0005 to 0.003 B. UNS: 0.18 to 0.53 C. 0.75 to I .OO Mn. 0.035 P max. O.O-lO S max. 0.15 to 0.30 Si. 0.40 to 0.60 Cr. O.OOOS B min. UNS H50501 and SAE/AISI 50B50H: 0.47 to 0.5-l C. 0.65 to I. IO Mn. 0. IS to 0.35 Si, 0.30 to 0.70 Cr. B (can be expected to be 0.0005 to 0.003 percent)
Similar
Steels (U.S. and/or
Annealing. For a predominately spheroidized structure. heat to 750 “C t I380 “F). cool rapidI> to 705 “C ( I300 “F). then cool to 650 “C ( I200 “F). at a rate not to exceed 6 “C I IO “F) per h: or heat to 750 “C ( I380 OF). cool rapidly to 675 “C ( I Z-IS ‘W. and hold for I2 h Hardening.
SOBSO. LINS G50501; ASTM AS 19; SAE J-IO-I. 5412.5770; t&r.) DIN I .7 138; (Jap.) JIS SUP I I. 50B50H. UNS HSOSOI; ASThl ,430-k SAE Jll68; (Ger.) DIN 1.7138; (lap.) JIS SUP I I
Characteristics.
Borders between what is usually considered as a medium-carbon and a high-carbon steel. depending on the precise carbon content. n hich also controls the as-quenched surface hardness. A range of approximately 56 to 62 HRC can be expected. The 0.30 to 0.70% chromium and the boron treatment produce a relativeI> high hardenability. Lksd for a variety of applications. u here its hardenability is ad\ antageous. such as heavy-duty springs
Forging.
Heat to 1230 “C (2250 “F) maximum. Do not forge after of foging stock drops below approximateI> 925 “C (I 695 “F)
Parts made from SOBSOH should be tempered immediately after they have been uniformly quenched to near ambient temperature. Best practice is to place uorkpieces into the tempering furnace just before they have reached room temperature. ideally when the) are in the range of 38 to 50 “C (I 00 to I20 ‘Fj. Tempering temperature must be selected based upon the final desired hardness
Recommended l
Normalizing.
I 2 3 1 5 6 7 8 Y IO II I:!
I.% 3.16 1.74 6.32 7.90 9.48 Il.06 12.6-t I-i.12 15.80 17.38 I8.%
l l
Heat to 870 “C ( 1600 “FI. Cool in air
l
Heat Treating
5085OH: End-Quench Distance from quenched surface 916in. mm
l
Practice
Recommended
65 65 6-t 6-l 63 63 62 62 61 60 60 59
l
Hardenability
Bardness, HRC min max 59 59 58 57 56 55 52 41 -I2 37 3s 33
at 845 ‘C ( 1555 “F), and quench in oil
Tempering.
l
temperature
Austsnitize
Foreign).
Distance from quenched surface 916 in. mm 13 I-l 15 I6 18 20 22 3-l 26 28 30 31
20.S-l ‘1.12 23.70 25.28 28.4-t 31.60 31.76 37.92 -Il.08 44.2-i -17.40 SO.56
Aardness, BRC max 58 57 56 5-l 50 -17 4-l II 39 38 37 36
21 20
Processing
Sequence
Forge Normalize AMY Rough and semifinish machine Austcnitire and quench in oil Temper Finish machine
50950,50950H:
Hardness
sents an average
based
vs Tempering
on a fully quenched
Temperature. structure
Repre-
Alloy Steel I393
50B50H: Hardenability “C (1600 “F). Austenitize:
iardness >urposes I distance, q m
1.s 3 5 7 9 11 13 15 20 25 30 35 40 45 50
Hardness purposes I distance, I,/,fj in. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 18 20 22 24 26 28 30 32
Curves. Heat-treating 845 “C (1555 “F)
limits for specification Hardness, HRC Maximum Minimum 6.5 65 65 64 63 63 62 62 59 54 49 44 40 38 37
59 59 59 51 55 52 46 39 32 29 27 26 24 22 20
limits for specification Hardness, HRC hlavimum Minimum 65 65 64 64 63 63 62 62 61 60 60 59 58 51 56 54 50 47 44 41 39 38 31 36
59 59 58 57 56 55 52 41 42 37 35 33 32 31 30 29 28 27 26 25 24 22 21 20
temperatures
recommended
by SAE. Normalize (for forged or rolled specimens
only): 870
394 / Heat Treater’s
Guide
50860,50B60H Recommended
Chemical
COIIIpOSitiOn. 50860. AIM: 0.56 to 0.64 C. 0.75 to I .OO Mn. 0.035 P max. 0.040 S max. 0.15 to 0.30 Si. 0.40 to 0.60 Cr. 0.0005 to 0.003 B. UNS: 0.56 to 0.64 C. 0.75 10 1.00 Mn. 0.035 Pmax. 0.040 S max. 0.15 to 0.30 Si. 0.40 to 0.60 Cr. 0.0005 B min. UNS I-I50601 and SAE/AISI 50B6OH: 0.55 10 0.65 C. 0.65 to I. IO Mn. 0.15 to 0.35 Si. 0.30 to 0.70 Cr. B (can be expected to be 0.0005 to 0.003 percent)
Similar
Steels (U.S. and/or Foreign). 5OB60. UNS GS0601; ASTM A5 19; SAE 5404. J412, J770. 50B6OR. UNS H50601; ASTM A304; SAE Jl268
Characteristics. Has the same general characteristics as other boroncontaining steels. With the higher carbon content, an as-quenched hardness in the range of approximately 58 to 63 HRC can be expected. The hardenability of this grade is quite high. Both the top and the bottom boundaries of the hardenability band are straight lines for significant distances from the quenched end. Used for parts lhat demand high hardenability. especially where economy is a factor. This steel. similar to other boron-containing steels. represents a cost-effective way of achieving high hardenability Forging.
Heat LO I205 “C (2200 “F) maximum. Do not forge after temperature of forging stock drops below approximately 925 “C ( I695 “F). Because of high hardenability, forgings. especially complex shapes. should be cooled slowly from the forging operation to minimize the possibility of cracking. Forgings may be slow cooled by either placing them in a furnace or burying them in an insulating compound
50B60l-l: End-Quench Distance from quenched surface l/16 in. mm I 2 3 1 5 6 7 8 9 IO II I?-
1.58 3.16 4.75 6.32 7.90 9.48 11.06 12.6-I 14.22 IS.80 17.38 I a.96
Hardenability
Eardness, ERC max min 60 __.
65 6.5 64 64 64
60 60 60 60 59 57 53 47 42 39 37
Distance from quenched surface ‘&j in. mm I3 II 15 I6 I8 20 22 2-l 26 28 30 32
20.54 22.12 23.70 25.28 28.4-t 31.60 34.76 37.92 41.08 44.24 47.40 50.56
Eardlless. ARC miw min 63 63 63 62 60 58 55 53 51 49 -17 44
36 35 3-l 41 33 31 30 29 28 21 26 25
Normalizing.
Heat Treating
Practice
Heal LO870 “C ( 1600 “F). Cool in air
Annealing.
For a predominately spheroidized structure. which is usually favored for this grade, heat to 750 “C (I 380 “F), cool rapidly to 700 “C ( I290 “F). then cool to 655 “C ( I2 IO “F). at a rate not to exceed 6 “C (IO “F) per h: or heat 10 750 “C (I 380 “F). cool rapidly to 650 “C ( 1200 “F), and hold for I2 h
Hardening.
Austenitize
at 845 “C (I 555 “F). and quench in oil
Tempering.
Selection of tempering temperature depends on the fmal properties desired. To prevent cracking, make sure parts have reached a uniform temperature throughout each section, and then place them in a tempering furnace before ambient temperature is reached. 38 to 50 “C (100 to I20 “F) is considered ideal
Recommended l l l l l l l
Processing
Sequence
Forge Normalize Anneal Rough and semitinish machine Austenitize and quench Temper Finish machine
50860: Hardness vs Tempering Temperature. Normalized at 870 “C (1600 “F), quenched from 845 “C (1555 “F) in oil, tempered in 56 “C (100 “F) intervals in 13.7 mm (0.540 in.) rounds. Tested in 12.8 mm (0.505 in.) rounds. Source: Republic Steel
Alloy Steel / 395
50B60H: Hardenability Curves. Heat-treating “C (1600 “F). Austenitize: 845 “C (1555 “F)
Hardness purposes I distance, nm
limits for specification Eardness, HRC Maximum Minimum
.s
I 3 5 !O !S 10 15 10 IS i0
iardness wrposes distance.
‘16b.
65 65 65 62 59 56 52 18 1.5
60 60 60 60 59 57 Sl 44 36 34 32 30 78 27 25
limits for specification Aardness, ARC Maximum Miuimum
65 65 6-l 6-l 6-l 63 63 63 62 60 58 55 53 51 49 37 44
60 60 60 60 60 59 57 53 17 12 39 37 36 35 34 34 33 31 30 29 28 37 26 2s
temperatures
recommended
by SAE. Normalize (for forged or rolled specimens
only): 870
396 / Heat Treater’s
Guide
5117 Chemical
Composition.
5117. AISI and UNS: 0.15 100.20 C. 0.70
to 0.90 hln. 0.035 P max. 0.040 S max. 0. IS to 0.30 Si. 0.70 to 0.90 Cr
Similar
Steels (U.S. and/or Foreign).
UNS
Gs I I 70
Characteristics. A slightly modified version of 5 IX. The carbon range is lower, hut the ranges for the two steels overlap. Although there is no H version of 5 I 17. hardenability is expected to he very close to that of S I2OH. As-quenched hardness for 51 I7 (no case) usually ranges from 36 to -II HRC.’ Readily forgeable and weldable with alloy steel welding practice. Definitely a case hardening grade and is used for parts that require kther carburizing or carbonitriding~ For further details see 5 l20H Forging. temperature
Heat to 12-15 “C (2275 “F) maulmum. Do not forge after of forging stock drops beIon approximately 870 “C t 1600 “F)
Recommended Normalizing.
Heat Treating
Practice
Heat to 935 “C t 1695 “FL Cool in air
Annealing.
Not usually requtred for this grade. Structures that are well suited to machining are generally ohtained hy normalizing or hy isothermal annealing after rolling or forgins. Isothermal annealing is accomplished by heating to 700 “C t 12570 “FJ, and holding for 8 h
Case Hardening. See recommended carhurizing, carhonitriding. and tempering procedures described for 4 I I SH. Ion nitriding and gas nitriding are alternative processes
Recommended l l l l l l l
Forge Normalize Anneal (optional) Rough and senitinijh Case harden Temper Finish machine
Processing
Sequence
machine
5117: Hardness vs Tempering Temperature. erage based on a fully quenched structure
Represents
an av-
396 / Heat Treater’s
Guide
5120,512OH Chemical
Composition.
5120. AISI and UNS: 0. I7 to 0.22 C. 0.70
to 0.90 hln, 0.035 P max. 0.040 S max. 0.15 to 0.30 Si. 0.70 to 0.90 Cr. IJNS H512OOand SAE/AISI 5120H: 0.17 to 0.23 C. 0.60 to I .OOhln. 0. IS to 0.35 Si. 0.60 to 1.00 Cr
Similar Steels (U.S. and/or
Foreign).
5120.
ASTM A322. A33l. ASl9: SAE J-101. 5770: (Ger.) .AFNOR 20 MC 5.5120H. UNS HS 1200: ASThf A304 DIN I .7147; (Fr.) AFNOR 20 hfC 5
UNS GS 1200: DIN 1.7147: (Fr.) SAE J 1268: (Ger.)
Characteristics. A low-alloy carburizing grade. An as-quenched hardness of approximately 38 to 4-I HRC can normally be expected. This range represents the core hardness of carhurized 5 I20H. Would not be considered it high hardenability steel. but it is similar to II IXH in hardenahility Forging.
Heat to I245 “C (2275 ‘F) maximum. Do not forge after temperature of forging stock drops below approximately 870 ‘C I I600 “F)
Recommended Normalizing.
Heat Treating
Practice
Heat to 925 “C t I695 “F). Cool in air
Annealing. Best machining structures lue obtained hy hesting to 800 “C t 1475 “FL cooling rnpidly to 675 Y f 1215 “F). and holding for IO h Tempering. tempered tolerated
PHIIS that hove been crtrburized or carbonitrided should be at 150 ‘C (300 “FL or higher if some loss of h‘ardness can be
Case Hardening. tempering process
procedures
Recommended l
Forge Normalize
.
AnIlZd
l
See recommended carhurizing. carbonitriding, and described for -! I I8H. Ion mtriding IS an alternative
Processing
Sequence
Rough and semitinish machine Carhurize. diffuse and quench. or carhonitride . Temper l Finish muchine if required l
l
and quench
Alloy Steel 1397
5120, 5120H: Hardness vs Tempering Temperature. Represents an average based on a fully quenched structure
5120H: End-Quench Hardenability Distance from Hardness, HRC min max I 2 3 1 5 6 7 8 9 I0 II I?
I.58 3.16 4.7-l b.32 7.90 9.18 I I .M Ix4 l-l.22 IS.80 17.38 18.96
48 46 -II 36 33 30 18 '7 25 2-l 23 '2
-IQ 34 28 23 20
Distance frum quenched surface ‘&in. mm I3 l-l I5 I6 18 20 22 2-l 26 18 30 31
20.54 '2.12 23.70 '5.28 78.4-l 31.60 34.76 37.91 41.08 4-4.2-I 17.40 50.56
Hardness. HRC ma\ 21 'I 20
398 / Heat Treater’s
Guide
5120H: Hardenability (1700 “F). Austenitize:
Curves. Heat-treating 925 “C (1700 “F)
iardness wrposes
limits for specification
I distance, lull
Eardnes, Maximum
I.5 I i I I 1 3 5 !O !S
iardness wrposes I distance,
116in. 1 I
i i , I I ) 10 I ,2 3 -I 5 6
ERC Minimum
48 46 -II 3-l 31 29 27 25 22
40 3-l 27 22 20
limits for specification Eardnesr, BRC Minimum Maximum 48 46 II 36 33 30 28 27 25 2-l 23 22 21 21 20
40 31 28 23 20
temperatures
recommended
by SAE. Normalize (for forged or rolled specimens
only): 925 “C
Alloy Steel / 399
5130,5130H,
5130RH
CheITIiCSl COIIIpOSitiOn. 5130. AISI and UNS: 0.28 to 0.33 C. 0.70 to 0.90 Mn. 0.035 P max. 0.040 S max. 0.15 to 0.30 Si. 0.80 to 1.10 Cr. UNS H51300 and SAE/AlSI 5130H: 0.27 to 0.33 C, 0.60 to I .OO Mn, 0. I5 to 0.35 Si. 0.75 to I .20 Cr. SAE5130RH: 0.28 to 0.33 C, 0.70 to 0.90 Mn, 0. IS to 0.35 Si. 0.80 to I. IO Cr
Similar Steels (U.S. and/or Foreign). 5130. UNS G5 1300: SAE 5304. J412. 1770; (Ger.) DIN 1.7030; (U.K.) B.S. 530 A 30. 530 H 30. 513OH.llNS H51300; ASTM A304,A914;SAEJl268. Jl868;(Ger.) DIN 1.7033: (Fr.) AFNOR 32 C 3: (Ital.) UN1 31 Cr 4 KB: (Jap.) JIS SCr 2 H. SCr 2; (U.K.) B.S. 530 A 32.530 H 32 Characteristics. A medium-carbon alloy steel. Chromium is the sole alloying element; manganese in the range of 5 l30H is not considered an alloy. Hardenability is considered fairly high. Depending on the specific carbon content. as-quenched hardness in the range of approximately 16 to 53 HRC can be expected. Can be welded. but alloy steel welding practice is mandatory
Annealing. For a predominately pearlitic structure, heat to 845 “C (1555 “F), cool rapidly to 755 “C ( 1390 “F), then cool to 670 “C ( 1240 OF). at a rate not to exceed I I “C (20 “F) per h; or heat to 845 “C (1555 “F). cool rapidly IO 675 “C (1245 “F), and hold for 6 h. For a largely spheroidized structure, heat to 790 “C (1155 “F). cool rapidly to 690 “C (I275 “F), and hold for 8 h Hardening. Austenitize at 855 “C (IS70 “F), and quench in oil. Ion nitriding, gas nitriding. liquid carburizing. and gas carburizing are suitable processes Tempering.
Reheat after quenching the desired hardness
Recommended l l
Forging. temperature
Heat to 1230 “C (2250 “F) maximum. Do not forge after of forging stock drops beIon! approximately 870 “C ( I600 “F)
Recommended Normalizing.
Heat Treating Heat to 900 “C (I650
Practice “FL Cool in air
l l l l l
Processing
to the temperature
that will result in
Sequence
Forge Normalize Anneal (preferably spheroidize) Rough machine Austenitize and quench Temper Finish machine
5130: Hardness vs Tempering Temperature. Normalized at 900 “C (1650 “F), quenched
from 870 “C (1600 “F) in water.
tempered
in 56 “C (100 “F) intervals in 13.7 mm (0.540 in.) rounds. Tested in 12.8 mm (0.505 in.) rounds. Source: Republic Steel
400 / Heat Treater’s
Guide
5130H: End-Quench Hardenability Distance from quenched surface !j6iu. mm
Eardnes. ERC min max
Distance from quenched surface Qhin. mm
Hardness. HRC man min
5130: Depth of Case vs Time and Temperature. 57.2 mm (2.25 in.) outside diameter by 165 mm (6.5 in.), oil quenched. ized at temperatures indicated
Carbur-
Alloy Steel / 401
5130H: Hardenability (1650 “F). Austenitize:
Hardness purposes I distance, nm I .5
iardness 3urposes I distance, /ifI in.
0 I 7 ; -I s 6 8 !O 12 !-I !6 !8 0 P
Curves. Heat-treating 870 “C (1600 “F)
limits for specification Elardness, HRC Maximum Minimum 56 55 s3 51 48 45 -I’ 39 35 33 31 30 28 26 2-l
49 46 12 37 33 30 21 2.5 21
limits for specification Hardness, HRC Maximum Minimum 56 ss 53 51 49 17 IS -12 40 38 37 36 3s 34 34 33 32 31 30 29 27 26 2s 2-l
49 46 43 39 35 32 30 18 26 2s 23 ‘2 21 20
temperatures
recommended
by SAE. Normalize (for forged or rolled specimens
only): 900 “C
402 / Heat Treater’s
Guide
5130RH: Hardenability
Curves. Heat-treating
“C (1650 “F). Austenitiie:
870 “C (1600 “F)
Hardness purposes
limits for specification
I distance.
Elardness, Maximum
‘/,6 in. I 2 3 1 5 5 7 B 3 10 II II 13 I4 IS 16 I8 20 22 2-l 26 28 30 32
Hardness purposes J distance, mm I.5 3 5 7 9 II I3 I5 20 IS 30 35 40 xi 50
EIRC Minimum 50 47 44 41 37 35 33 31 29 27 1-6 25 24 23 32 21 20
55 53 51 49 46 44 42 39 31 35 34 33 32 31 30 29 28 27 26 2s 24 23 22 ‘I
limits for specification Elardoess, Maximum 55 53 51 48 45 42 39 36 32 29 28 26 74 23 21
BRC Minimum 50 47 4-l 39 36 33 31 28 2-I 21 ‘0
temperatures
recommended
by SAE. Normalize (for forged or rolled specimens
only): 900
Alloy Steel / 403
5132,5132H Chemical
Composition. 5132. AISI and UNS: 0.30 to 0.35 C. 0.60 IO 0.80 Mn. 0.035 P max. 0.040 S max. 0.15 to 0.30 Si. 0.75 to 1.00 Cr. UNS A51320 and SAE/AISI 51328: 0.7-9to 0.35 C. 0.50 to 0.90 hln. 0. IS to 0.35 Si. 0.65 to I. IO Cr Similar
Steels (U.S. and/or Foreign).
5132.
UNS
GS 1320;
ASTM A322, A331, A505, ASl9: SAE J404. J-412, 5770; (Ger.) DIN I .7033; (Fr.) AFNOR 32 C 4; (Ital.) UN1 34 Cr 4 KB; (Jap.) JIS SCr 2 H. SCr 2: (U.K.) B.S. 530 A 32, 530 H 32. 51328. LINS HSl320: ASTM A304: SAE J1268; (Ger.) DfN 1.7034: (Fr.) AFNOR 38 C 4; (Ital.) 1lNI 38 Cr -I KB; (Jap.) JIS SCr 3 H; (U.K.) B.S. 530 A 36.530 H 36, Type 3
Characteristics.
Varies only slightly in composition from Sl30H. General characteristics are essentially the same as those for 5130H. The slightly higher carbon range of 5 l32H raises the maximum as-quenched hardness to approximately 48 to 55 HRC. although the hardenability of 5 l32H can be slightly less than that of 5 I30H because of the possibility of a lower chromium content. This grade can be welded. but alloy steel welding practice is mandatory
rate not to exceed I I “C (20 “F) per h: or heat to 845 “C (1555 “F), cool rapidly to 675 “C (I245 “F), and hold for 6 h. For a largely spheroidized structure. heat to 790 “C ( 1455 “F). cool rapidly to 690 “C (I 275 “F), and
hold for 8 h
Hardening. nitriding
Austenitize and gas nitriding
at 855 “C (IS70 “F), and quench are suitable processes
Tempering.
Reheat after quenching the desired hardness
Recommended l l l l l l l
Processing
to the temperature
in oil. Ion
that will result in
Sequence
Forge Normalize Anneal (preferably spheroidize) Rough machine Austenitize and quench Temper Finish machine
Forging.
Heat to 1230 “C (2250 “F) maximum. Do not forge after temperature of forging stock drops below approximately 870 “C (I600 “F)
Recommended Normalizing. Annealing. ‘F). cool rapidly
Heat Treating
Practice 5132: Microstructure.
Heat to 900 “C ( I650 “F). Cool in air For a predominately pearlitic structure. heat to 815 “C (I 555 to 755 “C ( I390 “F), then cool to 670 “C ( I230 “F), at a
5132, 5132H: Hardness vs Tempering Temperature.
Repre-
sents an average based on a fully quenched structure
5132H: End-Quench Hardenability Distance from quenched surface V~6in. mm I 7 i 4
5 6 7 8 9 10 II I2
I.58 3.16 4.74 6.32 7.90 9.48 Il.06 12.64 14.22 IS.80 17.38 18.96
Eardoess, HRC max mia 57 56 5-l 52 SO -la 1s 42 40 38 37 36
SO -17 -I3 40 35 32 29 27 25 24 ‘3 22
Distance from quenched surface ‘116in. mm I3 II I5 I6 I8 20 ‘2 21 26 ‘8 30 32
20 s-t 72.11 23 70 25.28 28.44 31.60 34.76 37.92 -Il.08 44.2-l -17.10 50.56
Hardness, HRC max min 35 3-1 31 33 32 31 30 29 38 27 26 25
21 20
.._
.._
.
Nital, 1650x. Steel forging, austenitized at 645 “C (1555 “F) and water quenched. Some blocky ferrite (light areas) and bainite (dark, feathery constituent) in a matrix of marlensite
404 / Heat Treater’s
Guide
5132H: Hardenability (1650 “F). Austenitize:
Curves. Heat-treating 845 “C (1555 “F)
Hardness limits for specification wrposes I distance. nm
Hardness, HRC hlinimum Maximum
I.5
57
50
II 13 IS !O !5 10 15 U) 15 i0
56 51 5’ 49 45 4’ 39 35 33 .-1’ 31 29 27 25
47 43 38 33 29 ‘6 35 II
iardness wrposes I distance, 116io.
0 I 7 ; -I 5 6 8 !O I2 I4 16 18 10 i?
limits for specification Eardness, HRC hlinimum Maximum 51 56 s-1 52 50 48 46 42 40 38 37 36 3s 3-I 3-1 33 32 31 30 29 28 27 26 ‘S
50 -17 43 -IO 3s 32. 29 27 3 2-l 23 22 21 20
temperatures
recommended
by SAE. Normalize (forforged
or rolled specimens
only): 900 “C
Alloy Steel / 405
5135,5135H Chemical Composition. 5135. AISI and UNS: 0.33 IO 0.38 C. 0.60 10 0.80 Mn. 0.035 P max. 0.040 S max. 0.15 to 0.30 Si. 0.80 to I.05 Cr. UNSH513SOand SAE/AISI513SH:0.32 to0.3XC.0.50to0.90Mn.0.15 to 0.35 Si. 0.70 to I. I5 Cr Similar Steels (U.S. and/or Foreign).
5135. l!NS GS 1350; ASThI .43X. A33l. ASIY: SAE J4O-l. 5412.1770; Ger.) DIN I.7034 (Fr.) AFNOR 38 C 1: (Ital.) LlNl 38 Cr 4 KB: (Jap.~ JIS SCr 3 H: (U.K.) B.S. 530 A 36.530 H 3.51358. LlNS HS 1350; ASTM A30-k SAE J 1268; (Ger.) DIN 1.7035; (Fr.j AFNOR -I2 C -1: (Ital.) UN1 -II Cr -I KB, 40 Cr -I: (Jap.~
JIS SCr -1 H; (U.K.) B.S. 530 A 10,530 H -IO. 530 hl10.2
S I I7
Characteristics.
A low-allo) version of the carbon steels 1035 and 1038H. Because of the chromium addition. hardenahility of 513SH is considerably greater than for 1038H. When fully quenched. an as-quenched hardness of approsimatelq SO to 56 HRC can he expected. Can he welded. hut is susceptible to Lteld cracliing
Annealing.
For a predominately pearlitic structure, heat to 830 “C (I525 “F). cool rapidly to 740 “C ( 136s “F). then cool to 670 “C ( I140 “F), at a rate not to exceed I I “C (20 “F) per h: or heat to 830 “C ( I525 “F), cool rapidly to 675 “C ( IX “F). and hold for 6 h. For a predominately spheroidized structure. heat to 750 “C (I380 “F). cool rapidly to 690 “C (1275 OF). and hold for 8 h
Hardening. nitriding
Tempering.
Forging.
Heat to 1230 “C (3750 “FI maximum. Do not forge after of forging stock drops helow approximateI) 870 ‘C ( 1600 “F)
Recommended l l
l l l
Recommended Heat Treating Practice Normalizing. Heat to 870 “C ( I600 “F). Cool in air
After
at 815 “C (I555 “F). and quench are suitable processes
quenching.
reheat to the temperarure
in oil. Ion required
obtaining the desired hardness
l
temperature
Austenitize and gas nitridinp
l
Processing
Sequence
Forge Normalize Anneal (,preferahly spheroidize, Rough machine Austenitize and quench Temper Finish machine
5135, 5135H: Hardness vs Tempering Temperature. Represents an average
5135H: End-Quench Hardenability Distance from ‘/16in.
mm
Hardness, HRC min ma\
I
1.58 3.16 4.14 6.32 7.90 9.48 11.06 12.64 14.22 15.80 17.38 18.96
57 56 55 54 52 50 47 45 43 41 40
quenched surface
2 3 4 5 6 7 8 9 10 11 12
58
51 -VI 47 43 38 35 32 30 28 27 25 24
Distance from quenched surface l/16 in. mm
13 14 15 16 18 20 22 24 26 28 30 32
20.54 22.12 23.70 25.28 28.44 31.60 34.76 37.92 41.08 44.24 47.40 50.56
Hardness,
HRC max
min
39 38 37 37 36 35 3-l 33
23 22 21 21 20
32
32 31 30
based
on a fully quenched
structure
for
406 / Heat Treater’s Guide
5135H: Hardenability Curves. Heat-treating temperatures (1800 OF). Austenitize:
845 “C (1555 “F)
Hardness limits for specification purposes J distance, mm 1.5 3 5 I 9 11 13 1.5 20 25 30 35 40 45 50
Eardness. ERC Maximum Minimum 58 58 56 54 53 50 47 44 40 37 35 3-l 33 32 31
51 19 46
41 36 32 30 27 2.3 21
Hardness limits for specification purposes I distance, I116in.
I
1
3 IO
I1 12 13 14 15 16 I8 !O !2 !4 !6 !8 IO 12
Eardnes.
MZIXhWfl 58 57 56 55 54 52 50 47 45 43 41 40 39 38 37 37 36 35 34 33 32 32 31 30
EIRC
Minimum 51
49 47 -I3 38 3s 32 30 ‘8 27 25 24 23 22 21 21 20
recommended
by SAE. Normalize (for forged or rolled specimens
only): 870 “C
Alloy Steel / 407
5140,5140H, Chemical
5140RH
Composition.
5140. AISI and UNS: 0.38 to 0.43 C, 0.70
to 0.90 Mn, 0.035 P max. 0.040 S max. 0. I5 to 0.30 Si. 0.70 to 0.90 Cr. UNS H51400 and SAE/AISI 5140H: 0.37 to 0.44 C. 0.60 to I .OO Mn. 0. I5 to 0.35 Si, 0.60 to 1.00 Cr. SAE 514ORH: 0.38 to 0.43 C. 0.70 to 0.90 Mn. 0. I5 to 0.35 Si. 0.70 to 0.90 Cr
Similar
Steels (U.S. and/or Foreign). 5140. UNS ~51400; ASTM A322. A33 I, A505. A5 19; SAE J404, J-il2. J770; (Ger.) DIN I .7035; (Fr.) AFNOR 42 C 4; (Ital.) UNI 40 Cr 3. II Cr 4 KB; (Jap.) JIS SCr-1H;(U.K.)B.S.530A40.530H~,530M40,2Sll7.51~0R.UNS H5 1400; ASTM A304. A914; SAE J 1268, J 1868; (Ger.) DIN I .7006; (Fr.) AFNOR42C2.45CZ Characteristics. The characteristics described for 5 I35H generally apply for 5140H. Because the carbon range is higher, slightly higher as-quenched hardness of approximately 5 I to 57 HRC can be expected. The possibility of a slightly lower chromium content for 5lJOH makes no significant difference in hardenability. This grade can be welded. but is susceptible to weld cracking Forging. temperature
Heat to 1230 “C (2250 “F) maximum. Do not forge after of forging stock drops below approximately 870 “C (I 600 “F)
Recommended Normalizing.
Heat Treating
Practice
Annealing.
For a predominately pearlitic structure, heat to 830 “C (1525 “F), cool rapidly to 740 “C ( I365 “F). then cool to 670 “C ( I240 “F), at a rate not to exceed I I “C (20 OF) per h; or heat to 830 “C (I 525 “F). cool rapidly to 675 “C (I 245 “F), and hold for 6 h. For a spheroidized structure. heat to 750 “C (I 380 “F), cool rapidly to 690 “C (I 275 “F). and hold for 8 h
Hardening. Austenitize at 8-0 “C (1555 “F), and quench in oil. Ion nitriding, gas nitriding, carbonitriding, austempering and mat-tempering are alternative processes Tempering. obtaining
After quenching, the desired hardness
Recommended l l l l l l l
reheat to the temperature
Processing
required
for
Sequence
Forge Normalize Anneal (preferably spheroidize) Rough machine Austenitize and quench Temper Finish machine
Heat to 870 “C ( I600 “F). Cool in air
5140: Isothermal Transformation C. 0.68 Mn, 0.93 Cr. Austenitized 6 to 7
Diagram. Composition: 0.42 at 845 “C (1555 “F). Grain size:
5140: Hardness vs Tempering Temperature. Normalized at 870 “C (1600 “F), quenched from 845 “C (1555 “F) in oil, tempered in 56 “C (100 “F) intervals in 13.8 mm (0.545 in.) rounds. Tested in 12.8 mm (0.505 in.) rounds. Source: Republic Steel
408 / Heat Treater’s
1 2 3 4 5 6 7 8 9 IO II 12
I .58 3.16 4.74 6.32 7.90 9.48 II.06 12.64 11.22 15.80 17.38 18.96
60 59 58 57 56 5-l 52 SO 48 -16 45 43
Guide
53 52 50 48 -I3 38 35 33 31 30 29 28
I3 II I5 I6 I8 20 22 ‘4 26 28 30 32
20.5-I 22.12 23.70 25.28 28.U 31.60 31.76 37.92 -11.08 44.24 -17.-w 50.56
32 40 39 38 37 36 35 3-l 3-l 33 33 32
27 ‘7 35 25 24 23 21 20
5140: End-Quench Hardenability. Composition: 0.43 C, 0.80 Mn, 0.010 P 0.050 S, 0.26 Si, 0.02 Ni, 0.84 Cr, 0.02 MO. Grain size: 7 to 8. Austenitized
5140:
at 955 “C (1750 “F) as in production and austenitized
As-Quenched
Hardness
at 845 “C (1555 “F) in accordance
(Oil)
Single heat results; grade: 0.38 to 0.43 C, 0.70 to 0.90 Mn, 0.20 to 0.35 Si, 0.70 to 0.90 Cr; ladle: 0.43 C, 0.78 Mn, 0.020 P, 0.033 S, 0.22 Si, 0.06 Ni. 0.74 Cr, 0.01 MO; grain size 6 to 8
Surface
Eurdness, ERC ‘/2 radius
57 53 46 35
57 48 38 29
Size round in. f.4
i 2 .I
mm I3 ‘5 51 102
Source: Bethlehem Steel
Center 56 -15 35 20
with hardenability
specifications
Alloy
5140: Continuous
Cooling Curves. Composition: 0.42 C, 0.87 Mn. 0.25 Si, 0.89 Cr. Austenitized at 845 “C (1555 “F). Grain size: 8. AC,, 805 “C (1480 “F); AC,, 750 “C (1380 “F). A: austenite, F: ferrite, P: pearlite, B: bainite, M: martensite. Source: Bethlehem Steel
Steel / 409
5140: Tempering Temperature vs Furnace Cooling and Water Quenching. Tempered at 620 “C (1150 “F) for2 h. Source: Climax Molybdenum
5140: Distribution
of Case Depth after Carbonitriding. Carbonitrided at 775 “C (1425 OF) for 8 h and quenched in oil at 77 “C (170 “F). 25 tests on a steel pinion shaft
410 / Heat Treater’s
Guide
5140H: Hardenability (1800 “F). Austenitize:
Hardness purposes J distance, mm
limits for specification q ardness, ERC Maximum Minimum
1.5
60
3 5 7 9 II 13 I5 20 ‘5 30 35 -lo 45 50
59 58 51 55 53 50 47 42 39 36 35 34 33 32
Hardness purposes J distance, 916in. I 1 s i 5 5 7 3 3 IO
II II 13 I4 15 I6 18 !O !2 !-I !6 !8 lo 12
Curves. Heat-treating 845 “C (1555 “F)
53 52 50 35 40 35 32 30 28 25 23 21
limits for specification Eardness, ARC Maximum Minimum 60 59 58 57 56 5-l 52 50 48 46 45 43 42 40 39 38 37 36 35 31 34 33 33 32
53 52 SO 48 43 38 35 33 31 30 29 28 27 27 26 25 2-l 23 ‘I ‘0
temperatures
recommended
by SAE. Normalize (for forged or rolled specimens
only): 870 “C
Alloy Steel / 411
5140RH: Hardenability
Curves. Heat-treating
“C (1600 “F). Austenitize:
Hardness purposes I distance, ‘/,6 in. I
5 1 3 2 IO II I?
I3 I4 I5 lb I8 10 22 14 16 18 30 32
Hardness purposes J distance, mm I.5 3 5 7 9 II 13 I5 20 25 30 3s 40 -Is 50
845 “C (1555 “F)
limits for specification Eardness, EIRC Maximum
Minimum
59 58 57 55 53 51 18 -I6 4-l 13 II 40 39 37 36 35 34 33 32 31 30 30 29 29
54 53 51 49 45 ?I 38 36 34 33 32 31 30 29 28 27 26 25 34 23 22 21 20
limits for specification Eardness, BRC Minimum Mximum 59 58 57 55 52 18 46 4-l 39 35 33 32 31 30 29
5-l 53 51 -I7 42 38 36 3-l 30 27 3 2-l 22 21 20
temperatures
recommended
by SAE. Normalize (for forged or rolled specimens
only): 870
412 / Heat Treater’s
Guide
5147H Chemical to 0.57
Similar SAE
UN.3 HSlJ70and
COIIIpOSitiOn. C. 0.60 to I .05 Mn.
J-W
0. IS IO 0.35
Steels (U.S. and/or or J-l 13. but does appeu
.SAE/AISI 5147H: 0.4.5
Si. 0.80
Foreign). in SAE
5770.
to 1.3
This steel is no longer which is nou J I397
5147H: Hardenability
Curves. Heat-treating
(1600 “F). Austenitize:
845 “C (1555 “F)
Hardness purposes J distaace. mm I.S 3 5 1
9 II 13 1s 20 3 30 35 +o -Is 50
Recommended
Heat Treating
Practice
Cr
temperatures
in
Hardening.
recommended
Gas niukiing
and ion nitriding
are suitable
by SAE. Normalize (for forged or rolled specimens
processes
only): 870 “C
limits for specification Eardoess,
Maximum 61 61 64 63 62 61 60 60 58 57 ss 53 52 SO 19
H RC Minimum 57 56 55 53 5’ i; u 39 33 31 29 27 25 23 21
(continued)
Alloy Steel / 413
5147H: Hardenability
Curves. (continued) Heat-treating
only): 870 “C (1600 “F). Austenitize:
Hardness purposes J distance, 1.. . /16m.
1 2 3 4 5 6 I 8 9 10 11 12 13 14 15 16 18 20 22 24 26 28 30 32
845 “C (1555 OF)
limits for specification Hardness, HRC Maximum Minimum
64 64 63 62 62 61 61 60 60 59 59 58 58 57 51 56 55 54 53 52 51 50 49 48
57 56 55 54 53 52 49 45 40 37 35 34 33 32 32 31 30 29 21 26 25 24 22 21
temperatures
recommended
by SAE. Normalize
(for forged or rolled specimens
414 / Heat Treater’s
Guide
5150,515OH Chemical
Composition.
5150. AISI and UN% 0.4 IO 0.53 C. 0.70
to 0.90 Mn. 0.035 P max. 0.040 S max. 0.15 to 0.30 Si. 0.70 to 0.90 Cr. UNS EI515OOand SAE/AISI 515OH: 0.47 to 0.54 C. 0.60 to I .OO Mn. 0. I5 to 0.35 Si. 0.60 to 1.00 Cr
Similar
Steels (U.S. and/or
ASTM A322. A33l. I .7006: (Fr.) AFNOR
Foreign). 5150. UNS G5 1500; A505, ASl9; SAE J-W, JJl2. 5770: (Ger.) DIN 42 C 2,45 C 2.5150H. UNS H5 1500: ASTM A30-k
SAE Jl268
Annealing.
For a predominately pearlitic structure, heat to 830 “C (I 525 “F). cool rapidly to 705 “C ( I300 “F). then cool to 650 “C (I 200 “F), at a rate not to exceed I I “C (20 “F) per h; or heat to 830 “C ( IS25 “F). cool rapidly to 675 “C ( 1245 “F). and hold for 6 h. For a predominately spheroidized structure, heat to 750 ‘C (I380 “F), cool rapidly to 705 “C ( I300 “F). then cool to 650 “C ( I200 “F). at a rate not to exceed 6 “C (IO “F) per h: or heat to 750 “C ( 1380 “F). cool rapidly to 675 “C ( I245 “F), and hold for IO h
Hardening.
Characteristics.
Has a borderline carbon content. between a mediumcarbon and a high-carbon steel. When fully hardened, an as-quenched hardness of approximately 55 to 60 HRC is normal, slightly higher when the carbon is near the maximum of the allowable range. Hardenability is also considered as relatively high. Because of the high carbon content and the high hardenability, does not have good weldability
nitriding,
Tempering.
After quenching. vide the desired hardness
Recommended l
Forging. temperature
Heat to 1220 “C (2225 “F) maximum. Do not forge after of forging stock drops below approximately 870 “C ( 1600 “F)
l l l
Recommended
Heat Treating
Practice
l l
Normalizing.
Heat to 870 “C (1600 “F). Cool in air
Austenitize at 830 “C (IS25 “F), and quench in oil. Gas fluidized bed nhriding. and ion nitriding are suitable processes
l
reheat to the temperature
Processing
required
to pro-
Sequence
Forge Normalize Anneal (preferably spheroidire) Rough machine Austenitize and quench Temper Finish machine
5150: Isothermal Transformation Diagram. Composition: 0.48 C, 0.86 Mn, 0.023 P, 0.021 S, 0.25 Si, 0.18 Ni, 0.98 Cr, 0.04 MO. 0.09 Cu. Austenitized at 860 “C (1580 “F). Grain size 5 to 6
5150, 5150H: Hardness vs Tempering Temperature. sents an average based on a fully quenched structure
Repre-
Alloy Steel / 415
5150: Hardness vs Tempering Temperature. Normalized at 870 “C (1800 “F), quenched from 845 “C (1555 “F), tempered in 56 “C (100 “F) intervals in 13.7 mm (0.540 in.) rounds. Tested in 12.8 mm (0.505 in.) rounds. Source: Republic Steel
5150H: End-Quench Hardenability Distance from
Distance from quenched surface ‘&jin. mm
Hardness, ERC max min 1.58 3.16 -4.71 6.32 7.90 9.18 I I.06 12.64 IA.22 IS.80 17.38 18.96
2 3 .I 5 h 7 8 9 IO II 12
65 65 64 63 62 61 60 59 58 56 55 53
5150: As-Quenched
59 S8 57 56 53 49 42 38 36 31 33 33
13 I-l 1s 16 I8 20 22 21 26 28 30 32
Hardness
20.54 22.12 23.70 25.28 28.4-l 31.60 31.76 37.92 11.08 44.21 47.40 50.56
Eardoess, ERC min max 51 SO 48 -17 15 13 42 -II 40 39 39 38
31 31 30 30 29 28 27 26 2s 24 23 22
(Oil)
Single heat results; grade: 0.48 to 0.53 C, 0.70 to 0.90 Mn, 0.20 to 0.35Si,0.70to0.90Cr,ladle:0.49C,0.75Mn,0.018P,0.018S,0.25 Si, 0.11 Ni, 0.80 Cr, 0.05 MO; grain size 7 to 8
in.
Size round mm
Surface
Hardness, HRC ‘/: radius
Center
‘/> I 2 4
I3 25 51 I02
60 59 55 37
60 52 -l-l 31
59 50 40 29
Source: Bethlehem Steel
416 / Heat Treater’s
Guide
5150H: Hardenability
Curves. Heat-treating 845 “C (1555 “F)
(1600 “F). Austenitize:
iardness wrposes
limits for specification
I distance,
Rardnes, Maximum
q m
1.5 1
3 II
13 15 !O !5 10 I5 lo 15 i0
iardness wrposes I distance, 46 in.
1 8 9 10 11 12 13 14 15 16 18 20 22 24 26 28 30 32
RRC Minimum
65 65 64 63 62 60 58 51 52 47 44 42 40 39 38
59 58 57 54 50 43 37 35 31 29 28 27 26 24 22
limits for specification Eardness, ARC hlioimum Maximum 65 65 64 63 62 61 60 59 58 56 55 53 51 50 48 47 45 43 42 41 40 39 39 38
59 58 57 56 53 49 42 38 36 34 33 32 31 31 30 30 29 28 27 26 25 24 23 22
temperatures
recommended
by SAE. Normalize (for forged or rolled specimens
only): 870 “C
Alloy Steel I417
5155,5155H Chemical
Composition.
5155. AISI and UNS: 0.5 1 to 0.59 C, 0.70 0.040 S max. 0.1s to 0.30 Si. 0.70 to 0.90 Cr. UNS H51550and SAE/AISI 51558: 0.50 to 0.6OC. 0.60 to I .OO Mn. 0. IS
to 0.90 Mn. 0.035 P
max.
to 0.30 Si. 0.60 to I .OO Cr
Similar
Steels (U.S. and/or Foreign). 5155. UNS GSISSO: ASTM A322, A33 I. AS 19: SAE J4O-l. J-II 2. J770; (Ger.) DUV I .7 176: (Fr.) AFNOR SS C 3. 51558. UNS HS 1550; ASThl A30-l: SAE J 1268; (Ger.) DIN I .7 176: (Fr.) AFNOR 55 C 3 Characteristics.
In general. the characteristics of 5 ISSH are the same as those discussed for 5 ISOH. However. the slightI> higher carbon range of SISSH makes a higher as-quenched hardness possible. 57 to 63 HRC is normal for fully quenched 5 I SSH. Although the hardenability patterns of 5 ISOH and 5 ISSH are similar. the entire band is slightI> higher for 5 ISSH. Because of the high carbon content and the high hardenabilitj, this grade does not have good weldability
Forging.
Heat to I 220 “C (2% “F) maximum. Do not forge after temperature of forging stock drops bslok+ approximateI> 870 “C t I600 “F)
Annealing.
For a predominately pearlitic structure, heat to 830 “C (I 525 “F). cool rapidly to 705 “C ( I300 “FL then cool to 650 “C ( 1200 “F). at a rate not to exceed I I “C (20 “F) per h; or heat to 830 “C (IS25 “F), cool rapidly to 675 “C t I315 “F), and hold for 6 h. For a predominately spheroidized structure. heat to 750 “C ( I380 “F), cool rapidly to 705 “C i I300 “F). then cool to 650 “C ( I200 “F), at a rate not to exceed 6 “C (IO “F) per h: or heat to 750 “C ( I380 “F). cool rapidly to 675 “C (I 245 “F). and hold for IO h
Hardening. nitriding
Heat Treating
Practice
After quenching. vide the desired hardness
Recommended l l l
l l
Normalizing.
Heat to 870 “C i 1600 “F). Cool in air
at 830 “C (IS25 “F), and quench in oil. Gas are suitable processes
Tempering.
l
Recommended
Austenitire and ion nitriding
l
Processing
5155, 5155H: Hardness
Dicmnce from quenched surface ‘/,6 in. mm I
Hardness. ARC max min
Distance from quenched surface %6 in. mm
Hardness, ARC min max
1.58 4.74 3.16
64 65
h0 58 59
13 I-l IS
20.54 22. II 23.70
1
6.32
6-l
57
16
25.28
31
5
7.90 9.48 II.06 12.6-I l-I.31 1580 17.38 18.96
63 63 62 62 61 60 59 57
55 52 -17 II 37 36 35 3-l
18 20 22 7-I 16 28 30 32
28.4-l 3 I .6O 31.76 37.92 41 08 44.2-l 17.10 50.56
31 31 30 29 28 27 xl 25
7 x 9
IO II
ss 51 52
3-l 33
;-3
h
II
Hardenability
required to pro-
Sequence
Forge Normalize Anneal (preferably spheroidire) Rough machine Austenitize and quench Temper Finish machine
sents an average
5155H: End-Quench
reheat to the temperature
based
vs Tempering
Temperature.
on a fully quenched
structure
Repre-
418 / Heat Treater’s
Guide
5155H: Hardenability
Curves. Heat-treating temperatures 845 “C (1555 “F) -
(1600 “F). Austenik
Hardness purposes J distance, mm 1.5 3 5 7 9 11 13 15 20 25 30 35 40 45 50
Hardness purposes J distance, %6in.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 18 20 22 24 26 28 30 32
limits for specification Eardness, EIRC Maximum MillhllUll
.. 65 65 64 64 63 61 60 56 50 46 44 43 42 41
60 60 59 56 53 48 40 37 34 32 30 29 28 27 25
limits for specification Hardness, ARC MSlXimlUU Minimum
.
60
65 64 64 63 63 62 62 61 60 59 51 55 52 51 49 47 45 44 43 42 41 41 40
59 58 51 55 52 47 41 31 36 35 34 34 33 33 32 31 31 30 29 28 27 26 25
recommended
by SAE. Normalize (for forged or rolled specimens
only): 870 “C
1
Alloy Steel / 419
5160,5160H,
5160RH
Chemical
Composition. 5160. AISI and UNS: 0.56 to 0.63 C. 0.75 to I .OOMn, 0.035 P max. 0.040 S max. 0.15 to 0.30 Si. 0.70 to 0.90 Cr. UNS H51600 and SAE/AISI 516OH: 0.55 to 0.65 C. 0.65 to I .OO Mn, 0. I5 to 0.35 Si, 0.60 to I.00 Cr. SAE 516ORH: 0.56 to 0.6-t C, 0.75 to I .OO Mn.
0. IS to 0.35 Si, 0.70 to 0.90 Cr
Similar
Steels (U.S. and/or
Foreign).
ASTM A322 A33l. A505. ASl9; SAE J-W H51600:ASThlA30&A914:SAE51268,J1868
5160.
UNS G51600; 5412. 5770. 5160H. UNS
Characteristics.
Detinitely considered a high-carbon alloy steel. Asquenched hardness of 58 to 63 HRC is considered normal. Sometimes values higher than this range are obtained, depending on the precise carbon content. Hardenability is slightly higher than that of 5lSSH. Used for a variety of spring- applications. notably flat springs. Often uses austempering .. as a method of heat treating
Forging. temperature
Heat to 1205 “C t2300 “F) maximum. Do not forge after of forging stock drops below approximately 870 “C (1600 “F)
rapidly to 675 “C (I215 “F). and hold for 6 h. For a predominately spheroidized structure, heat to 750 “C (I 380 “F). cool rapidly to 705 “C (1300 “F). then cool to 650 “C (I 200 “F). at a rate not to exceed 6 “C (IO “F) per h: or heat to 750 “C ( I380 “F). cool rapidly to 675 “C (1245 “F), and hold for IO h
Hardening. polymer.
Tempering.
After quenching, vide the desired hardness
Recommended Annealing.
Heat Treating
Practice
Heat to 870 “C ( I600 “F). Cool in air
For a predominately pearlitic structure. heat to 830 “C ( I525 “F). cool rapidly to 705 “C ( I300 “F). then cool to 650 “C ( 1200 “F). at a rate not to exceed I I “C (20 “F) per h; or heat to 830 “C ( IS25 “F). cool
reheat to the temperature
in oil or
required to pro-
Austempering.
Austenitize at 845 “C (I 555 “F), quench in molten salt at 315 “C (600 “F), and hold for I h. Parts are cooled in air from 315 “C (600 “F) and need no tempering. A spring temper hardness within the range of approximately 16 to 52 HRC is obtained
Recommended l
Normalizing.
Austenitize at 830 “C (IS25 “F), and quench Gas nitriding and ion nitriding are suitable processes
l l l l l l
Processing
Sequence
Forge Normalize Anneal (preferably spheroidize) Rough machine Austenitize and quench (or austemper) Temper (or austemper) Finish machine
5160: Isothermal Transformation
Diagram. Composition:
C, 0.94 Mn, 0.88 Cr, 0.22 MO. Austenitized Grain size 7
0.61 at 845 “C (1555 “F).
420 / Heat Treater’s
Guide
5160: Correlation of Annealing Practice with Surface Finish andTool Life in Subsequent Machining. (a) Annealed (pearlitic) microstructure, 241 HB, and surface finish of flange after machining eight pieces. (b) Partially spheroidized microstructure, 180 HB, and surface finish of flange after machining 123 pieces
5160: Hardness vs Tempering Temperature. Normalized at 870 “C (1600 “F), quenched from 845 “C (1555 “F) in oil, tempered in 56 “C (100 “F) intervals in 13.7 mm (0.540 in.) rounds. Tested in 12.8 mm (0.505 in.) rounds. Source: Republic Steel
5160:
As-Quenched
Hardness
(Oil)
Single heat results; grade: 0.56 to 0.64 C. 0.75 to 1 .OO Mn, 0.20 to 0.30Si,0.70to0.90Cr;ladle:0.62C.0.84Mn,0.010P,0.034S,0.24 Si, 0.04 Ni. 0.74 Cr, 0.01 MO; grain size: 6 to 8 Size round in.
mm
Surface 63 62 53 40
Aardness, ERC ‘/z radius 62 61 46 32
Center 62 60 43 29
Alloy Steel / 421
5160H: End-Quench Hardenability Distance from quenched surface &in. mm
Hardness, ERC max min
Distance from quenched surface ‘/lb in. mm
Hardness, ERC mas min
I ;')
I.58 4.74 3.16
.::
60 60
I3 IS I-I
20.51 23.70 22.11
58 5-l 56
3s 3-l 35
-I 5 6
6.5 65 6-l 61 63 62 61 60
99 58 56 5' 37 -I-' 39 37
16 I8 20 2' 2-l 30 26 28
2.5 28 18.U 3 I .60 34.76 37.91 4-4.2-l 47.40 -I I .0x
52 48 47 46 -IS -I? u -43
34 33 32
8 III90
6.31 7.90 9.48 Il.06 12.6-l l-l I7 IS 3x 80 22
;Lj
I2
I896
59
36
32
SO26
-I2
27
7
5160: Continuous
Cooling Curves. Composition: 0.63 C, 0.86 Mn, 0.23 Si, 0.83 Cr. Austenitized at 845 “C (1555 “F). Grain size: 7 ‘Is. AC,, 780 “C (1435 “F); AC,, 755 “C (1390 “F). A: austenite, F: ferrite, P: pearlite, B: bainite, M: martensite. Source: Bethlehem Steel
5160:
Section
Thickness
vs
Austempered
Hardness.
Quenched in agitated salt containing some water. Rockwell C hardness values converted from microhardness readings taken with a 100 g (3.53 oz) load. Low values of surface hardness result from decarburization. (a) 24.6 mm (0.967 in.) diam. Austenitized at 900 “C (1650 “F) and quenched in salt at 300 “C (570 “F) for 15 min. High hardness at center because of segregation. (b) 26.29 mm (1.035 in.) diam. Austenitized at 940 “C (1725 “F) and quenched in salt at 315 “C (600 “F) for 15 min
422 / Heat Treater’s
5160: Microstructures.
Guide
(a) 4% picral with 0.05% HCI. 500x. Hot rolled coil-spring steel, austenitized at 870 “C (1600 “F) for 30 min and oil quenched. Untempered martensite (dark, needlelike constituent) and retained austenite (light constituent). (b) 4% nital. 4% picral, mixed 1 to 1: 1000x. Same steel and heat treatment as (a), except at a higher magnification. Untempered martensite (dark gray constituent) and the retained austenite (light constituent are now more clearly resolved). (c) 4% nital. 4% picral, mixed 1 to 1; 1000x. Same steel as (a), except tempered at 205 “C (400 “F) after austenitizing and quenching. Predominantly tempered martensite (dark), with small particles of ferrite (white). (d) 2% nital. 11Ox. Spring steel, 16.1 mm (0.632 in.) diam, austenitized at 870 “C (1600 “F) for 5 min, hot coiled, oil quenched at 60 “C (140 “F), tempered at 425 “C (795 “F) for 40 min. Note tempered martensite and decarburization. (e) 2% nital, 275x. Same steel and treatment as(d). except at a higher magnification. Surface decarburization (white area near top of micrograph) occurred in the bar mill, while the steel was at about 1150 “C (2100 “F). ( f) 4% nital, 4% picral, mixed 1 to 1; 1000x. Hot rolled steel. austenitized at 870 “C (1600 “F) for 30 min, oil quenched, tempered at 540 “C (1000 “F) for 1 h. Predominantly tempered martensite (dark). with some ferrite (white)
Alloy Steel I423
516OH: Hardenability Curves. Heat-treating temperatures recommended by SAE. Normalize (for forged or rolled specimens only): 870 “C (1800 “F). Austenitize: 845 “C (1555 “F) iardness wposes I distance,
lull
limits for specification Earducss, ERC Maximum Minimum
3
. I 3 5 0 s 0 5 0 5 0
iardness wrposes distance,
$6io.
1 0 I 2 3 4 5 6 8 0 2 4 6 8 0 2
65 64 64 62 58 53 49 46 44 42 41
60 60 60 59 57 52 46 40 36 34 32 30 28 27 27
limits for specification Hardness, ERC Maximum Minimum
65 65 64 64 63 62 61 60 59 58 56 54 52 48 47 46 45 44 33 43 42
60 60 60 59 58 56 s2 47 42 39 37 36 35 35 34 34 33 32 31 30 29 28 28 27
424 / Heat Treater’s
Guide
5160RH: Hardenability
Curves. Heat-treating
“C (1600 “F). Austenitize:
845 “C (1555 “F)
Hardness purposes J distance. !I,6in.
limits for specification Eardness, Maximum
I 2 3 4 5 6 7 8 9 IO II I2
65 6.5 6.i, 65 6-l 63 6Z 60 58 S6 55 s3
I3
51
I-l
SO
IS
?2
18 17 4-l -13 -II
?-I
II
16 18 30 32
40
I6 I8 10
Hardness purposes J distance, mm I .s
3 5
7 Y II I3 IS 20 75
30 3s
60 60 60 59 58 57 5-l SO 4s 32 40 39 38 37 36 36 3s 3-I 33 32 31 30 29 T!9
39 39 38
limits for specification Eardoess, Maximum 65 6.c 65 65 63 62 60 57 52 17 -I3 II
-lo
40
IS
39 38
so
BRC Minimum
ARC Minimum MI 60 60 59 57 5-t -I9 13 38 36 31 32 31 30 ‘9
temperatures
recommended
by SAE. Normalize
(for forged or rolled specimens
only): 870
Alloy Steel / 425
51 B60,51 Chemical
B60H
Composition.
51~60. AM: 0.56 to 0.6-1C. 0.75 to 1.00
hln. 0.035 P max. O.MO S mas. 0. IS to 0.30 Si. 0.70 to O.YO Cr. 0.0005 to 0.003 B. UNS: 0.56 too.64 C, 0.75 to 1.00 hln, 0.035 Pmax, O.O-lO S max. 0.15 to 0.30 Si, 0.70 to 0.90 Cr. 0.0005 B min. UNS H51601 and SAE/AISl51B60H: 0.55 to O.hS C. 0.65 to I. IO hln. 0. IS to 0.35 Si. 0.60 to I .OO Cr. B (can he expected to be 0.0005 to 0.003 percent)
Similar
Steels (U.S. and/or
Foreign).
51B60. UNS GSI 601:
.+,STILl ASl9: SAE J3O-i. 5112. 5770. 51B60H. A3o-t: SAE J I268
UNS HSl601:
ASTM
Characteristics.
With the exception of a slightly higher chromium content. 5 I B6OH has practicalI! the same characteristics as SOB60H. .bquenched hardness of 58 to 63 HRC can he expected. Hardenability of 51 BhOH is slightl) higher. because of the increase in chromrum
Forging. Heat to IlOS ‘C I 2300 “F) maximum. Do not forge after temperature of forging stock drops below approximutel! 925 “C (1695 “FL Because of high hardenability, forgmgs. especialI>; comples shapes. should he cooled slow I> from ths forging operation to mminize the possihilit} of crackinp. Forgings ma! he slob cooled by either placing them in a furnace or huqing them in an Insulating compound
For a prsdoninatel) spheroidized structure which is usually favored for this grade of steel. heat to 750 “C ( 1380 “F). cool rapidly to 700 ‘C ( 1190 “F). then cool to 655 “C ( I2 IO “F). at a rate not to exceed 6 “C t IO “F, per h: or heat to 750 ;‘C I 13X0 “F). cool rapidI) to 650 “C ( 1200 OF), and hold for 12 h
Hardening. nitridinp
Selection of tempering temperarure depends on the final properties desired. To prevent cracking, make sure parts have reached a uniform temperature throughout each section. and then place them in I tempering furnace hefore nmhient temperature is reached. 38 to SO “C (100 to I20 “F, is considered ideal
Recommended l l l l l
Heat to 870 “C I 1600 ‘FL Cool in air
l
Heat Treating
Austenitize at 815 “C ( IS55 “FL and quench in oil. Gas and ion niuidinp are suitnhle processes
Tempering.
Practice
Recommended Normalizing.
Annealing.
l
Processing
Sequence
Forge Normalize Anneal Rough and semitinish machine Austenitize and quench Temper Finish machine
51 B60: Isothermal
Transformation
0.64 C. 0.88 Mn, 0.83 Cr. 0.0006 “F). Grain size 6 to 7
51 B60: End-Quench Hardenability. Mn, 0.83 Cr. 0.0006 6 to 7
B. Austenitized
Diagram. Composition:
B. Austenitized
at 845 “C (1555
Composition: 0.64 C, 0.88 at 845 “C (1555°F). Grain size
426 / Heat Treater’s
Guide
51 B60: Hardness vs Tempering Temperature. Normalized at 870 “C (1600 “F), quenched from 845 “C (1555 “F) in oil, tempered in 56 “C (100 “F) intervals in 13.7 mm (0.540 in.) rounds. Tested in 12.8 mm (0.505 in.) rounds. Source: Republic Steel
51 B60H: End-Quench Distance from quenched surface
&h. 1 2 3 4 5 6 7 8 9 10 11 12
mm 1.58 3.16 4.75 6.32 7.90 9.48 11.06 12.64 14.22 15.80 17.38 18.96
Hardenability
Hardness, ARC max min _..
.__ . . _.. 65
60 60 60 60 60 59 58 57 54 50 44 41
Distance from quenched surface
l/h5in.
mm
13 14 15 16 18 20 22 24 26 28 30 32
20.54 22.12 23.70 25.28 28.44 31.60 34.76 37.92 41.08 44.24 47.40 50.56
Hardness, HRC max min 65 64 64 63 61 59 57 55 53 51 49 47
40 39 38 37
28 27 25
51860: Microstructures. (a) Picral. 1000x. Hot rolled steel bar, 31.8 mm (1 l/4 in.) diam, austenitized at 870 “C (1600 “F), air cooled (normalized); austenitized at 815 “C (1500 “F), water quenched. Untempered martensite, some retained austenite (white), fine spheroidal carbide. (b) Nital, 1000x. Hot rolled steel bar, 13.8 mm (1 l/4 in.) diam, austenitized and quenched to obtain a martensitic structure, then heated to 675 “C (1245 “F) for 15 h. Spheroidal carbide particles in a matrix of ferrite
Alloy Steel / 427
51 B6OH: Hardenability Curves. Heat-treating “C (1600 “F). Austenitize: 845 “C (1555 “F)
Hardness purposes I distance. am
limits for specification Eardness, HRC Minimum Maximum
I .s
60
1 3 II 13 IS !O !S 10 1s lo IS 50
60 60 60 59 58 55 51 -IO 37 35 32 30 28 25
Hardness purposes I distance, &$in.
65 63 61 57 s-l 51 -17
limits for specification Eat-does, ERC Minimum hlaximum
3 ) IO II I2 I3 I-t I5 I6 18 31 !2 !-I ?6 !8 10 12
65 65 6-l 64 63 61 59 57 55 53 51 49 47
60 60 60 60 60 59 58 57 5-l 50 4-l II 40 39 38 37 36 31 33 31 30 28 27 'S
temperatures
recommended
by SAE. Normalize (for forged or rolled specimens
only): 870
428 / Heat Treater’s
Guide
E51100 Chemical Composition. AISI and UNS: 0.98 to 1.10 C. 0.25 to 0.45 hln. 0.025 P max. 0.025 S max. 0. IS to 0.30 Si. 0.90 to I .I5 Cr Similar Steels (U.S. and/or Foreign). 1lNS Gs 1986; AhlS 6443. 6446.6449: ASTM A295 A322, A505. A519:SAEJ4045412.J770: (Ger.) DIN I.3503
Characteristics. One of only two alloy steels listed bj NISI \\hich contain carbon of near 1.0% or higher. The E prefix in the designation indicates that it is manufactured only by the electric furnace process. which is further indicated by the IO\V contents of phosphorus and sulfur. This gade and its companion. E52 100, are sometimes called tool steels because their composition is nearly identical with L2 grade of tool steel. However. neither ES II00 or ES2 100 is made by what is commonly considered as tool steel practice; they are both made in relativelq large quantities. Although ES I 100 does sene many commercial applications. it is used most extensively as a material for ball and ball race rolling element bearings. for which extremely high hardness is needed. There is no H version of this steel because the end-quench test is not often used to evaluate hardenabilitj of the VS~ high-carbon grades. It is. ho\rever. generally considered an oil-hardemng steel. so that its hardenability is considered as fairly high. As-quenched hardness generally ranges from 62 to 66 HRC. depending on the cooling power of the quenchant Forging. temperature
Heat to II50 “C (2100 “F) masimum. of forging stock drops below approximately
Annealing. For a predominantl! spheroidized structure. which is generally desired for machining as \\ell as heat treating. heat to 795 “C (1460°F). cool rapid11 to 750 “C t I380 “F). then cool to 675 “C. ( I345 “FL at a rate not to exceed 6 “C (IO “F) per h: or heat to 795 “C (I460 “Fj. cool rapidly to 690 “C ( I175 “F), and hold for I6 h Hardening. Austenitize at 845 “C ( 15% “F) in a neutral salt bath or in a gaseous atmosphere I\ ith a carbon potential of near I .08. and quench in oil Tempering.
After quenching, parts should be tempered as soon as they have uniformly reached near ambient temperature. 38 to 50 “C ( 100 to I20 “F) is ideal. Because of the high carbon content, parts must be tempered to at least I20 “C (250 “F) to convert the tetragonal martensite to cubic martensite. Most commercial practice calls for tempering at IS0 “C (300 “F). H hich does not reduce the as-quenched hardness to any significant amount. Li’hen a reduction in hardness from the as-quenched value of approximatcl) two points HRC can be tolerated. a tempering temperature of I75 “C (3-15 “F) is recommended. Sometimes subjected to higher tempering temperatures. 1%ith an accompan) ing loss of hardness
Recommended l l
Do not forge after
l
915 “C t 1695 “F)
l l
Recommended Normalizing.
Heat Treating
Practice
l l
Heat to 885 “C (1625 “FL Cool in air
Processing
Sequence
Forge Normalize Anneal t spheroidize 1 hlachine. including rouph grinding Austenitize and quench Temper Finish grind
E51100: Hardness vs Tempering Temperature. Represents average
lsased on a fully quenched
structure
an
428 / Heat Treater’s
Guide
E52100 Chemical Composition. AM: 0.98 to 1.10 C. 0.25 to O.-IS Mn. 0.025 P max. 0.025 S max. 0.15 to 0.30 Si. I .30 to 1.60 Cr. UNS: 0.98 to I.10 C. 0.15 to 0.X Mn. 0.015 P max. 0.025 S max. 0.70 to 0.30 Si. 1.30 to I .60 Cr Similar 6-W. SPEC (Ger.) 53-t A
Steels (U.S. and/or Foreign). UNS GS2986: 6U7; ASTM A27-l. A322. A331. A505. ASl9. A535. MlL-S-980. MJL-S-7120. hllL-S-Zl-t I; SAE J-IO-I. DIN 1.3505; (Fr.) AFNOR IOOC 6: (Ital.) UN1 lOOCr6: 99.535 A 99
AMS 6-WO. 44636: MUJ-II’. 5770: (U.K.) B.S.
Characteristics. Because E52 100 has the same composition as 5 I IO escept for a modest Increase m chromtum. the characteristics and commercoal applications are similar. The as-quenched hardnesses for the tmo steels can be the same (62 to 66 HRCJ. depending mainly on section thickness. Because of higher chromium content. the hardenability of ES2100 is someLt hat higher. Sometimes an attempt is made to evaluate hardness by the end-quench method. ES2100 is selected when greater section sizes and the increased hardenability are needed Forging. temperature
Heat to I IS0 “C (1100 “FJ maximum. Do not forge after of ForSinS stoch drops below approxtmately 915 “C (I 695 “F)
Alloy
Recommended
Heat Treating
Tempering.
Practice
Normalizing. Heat to 885 “C (1625 “FL Cool practice this alloy is nomtalized at 900 “C ( 1650 “F)
in air
Steel / 429
In aerospace
Annealing. For a predominantly spheroidired structure which is generally desired for machining as dell as heat treating. heat to 795 “C t l-160 “F). cool rapidly to 750 “C ( I380 “F). then cool to 675 “C ( 12-15 “Ft. at a rate not to exceed 6 “C I IO “F) per h; or heat to 795 “C ( I460 “FL cool rapidly to 690 “C ( I275 “F). and hold for I6 h. Parts are annealed at 775 “C ( 1125 “F) for 20 min. cooled to 740 “C (I 365 “F) at a rate not to exceed IO “C (20 “F) per h. and air cooled to ambient temperature Hardening. iwstenitize at 845 “C (IS55 “Ft in a neutral salt bath or in a gaseous atmosphere with a carbon potential of near I .OCr. and quench in oil. In aerospace practice, this alloy is austenitized at S-15 “C (IS55 “Ft. Ho\+ever. 815 “C (1500 “F) is pemissible for parts requiring distortion control. Parts are hardened from the spheroidize annealed condition or normalized condition. Parts are quenched in oil or polymer. Immediately after quenching, parts are refrigerated at -70 “C (-95 “F) or lomet-. held for I h minimum. then air barnled to room temperature. If parts have high propensity for cracking during refrigeratton. a snap temper IS recommended
After quenching. parts should be tempered as soon as they have uniformly reached near ambient temperature, 38 to 50 “C (100 to I20 ‘FJ is ideal. Because of the high carbon content, parts must be tempered to at least 120 “C (250 “F) to convert the tetragonal martensite to cubic martensite. Most commercial practice calls for tempering at 150 “C (300 “F). which does not reduce the as-quenched hardness to any significant amount. When a reduction in hardness from the asquenched value of approsimately two points HRC can be tolerated, a tempering temperature of I75 “C (3-0 “F) is recommended. Sometimes subjected to higher tempering temperatures. u ith an accompanying loss of hardness. In aerospace practice. at least t\
Recommended l l l l l l l
Processing
Sequence
Forge Normalize Anneal (spheroidire) Machine. including rough grinding Xustenitize and quench Temper Finish grind
E52100: Isothermal
Transformation
Diagram. Composition:
1.02 C, 0.36 Mn, 0.20 Ni. 1.41 Cr. Austenitized
at 845 “C (1555
“F). Grain size: 9
E52100: Hardness vs Tempering Temperature. Represents an average based on a fully quenched structure
430 / Heat Treater’s
E52100: End-Quench (1555 “F). Insufficient austenite
Guide
E52100: Continuous Cooling Curves. Composition: 1.06 C, 0.33 Mn, 0.32 Si, 1.44 Cr. Austenitized at 845 “C (1555 “F). Grain size: 9. AC,, 780 “C (1440 “F); AC,, 755 “C (1390 “F). A: austenite, F: ferrite, P: peartite, B: bainite, M: martensite. Source: Bethlehem Steel
Hardenability. Austenitized at 845 “C time to permit full carbide solubility in
E52100: End-Quench Hardenability. 13 mm (0.5 in.) diam bar. Composition: 1.02 C. 0.36 Mn, 0.20 Ni, 1.41 Cr. Austenitized at 845 “C (1555 “F). Grain size: 9
E52100: Influence of Agitation of Surface Hardness. Various section thicknesses,
martempered
in hot salt
E52100: Hardness Distribution. Steel rings, 100 heats. Heated at 790 “C (1455 “F) for 3 h. cooled rapidly to 725 “C (1335 “F), then cooled to 695 “C (1280 “F) at 8 “C (15 “F) per h, and air cooled. Hardness measurements were made on rings located at extreme positions in furnace load. Treatment resulted in spheroidized structure. Composition: 0.90 to 1.05 C, 0.95 to 1.25 Mn, 0.50 to 0.70 Si, 0.90 to 1.15 Cr
E52100: Variation of Brine11 Hardness Measurements on Annealed Plain Carbon and Low-Alloy Steels. 52100 seamless tubes were austenitized at 790 “C (1445 “F), rapid furnace cooled to 750 “C (1380 “F), then cooled to 695 “C (1280 “F) at 6 “C (10 “F) per h, and air cooled
I
I
I
Alloy Steel / 431
E52100: Austenitizing
Temperature
vs Grain Size and M,Temperature.
(a) Grain size; (b) MS temperature
E52100: Microstructures. (a) 4% picral with 0.05% HCI, 1000x. Steel bar, 123.8 mm (4.875 in.) diam, heated to 770 “C (1420 “F) for 10 h, held for 5 h, cooled to 650 “C (1200 “F) at 11 “C (20 “F) per h. furnace cooled to 28 “C (80 “F). Fine dispersion of spheroidal carbide in a matrix of ferrite. Prior structure for(b) to (k). (b) 4% nital. 4% picral, mixed 1 to 1; 500x. See (a). Austenitized at 790 “C (1455 “F) for t/2 h. oil quenched, tempered at 175 “C (345 “F) for 1 h. Black areas are bainite, gray areas tempered martensite, white dots are carbide particles that did not dissolve during austenitizing. (c) 4% nital, 4% picral, mixed 1 to 1: 500x. See (a), austenitized l/2 h at 845 “C (1555 “F) and oil quenched, then tempered same as (b). Tempered martensite and carbide particles (white) undissolved during austenitizing. Ghost lines are because of inhomogeneous distribution of carbon and chromium. (d) 4% nital, 4% picral, mixed 1 to 1; 500x. See (a), austenitized at 855 “C (1570 “F) for l/2 h, oil quenched, tempered at 260 “C (500 “F) for 1 h. Tempered martensite and undissolved carbide particles. Ghost lines less prominent because of higher austenitizing and tempering temperatures. See (c). (e) 4?0 nital, 4% picral, mixed 1 to 1; 500x. See (a). Austenitized at 845 “C (1550 “F) for % h, oil quenched, tempered at 400 “C (750 “F) for 1 h. Tempered martensite and a dispersion of carbide particles not dissolved during austenitizing. Ghost lines have nearly disappeared. Compare with (c) and (d). (f) 4% nital. 4% picral, mixed 1 to 1; 500x. See (a). Austenitized at 925 “C (1695 “F) for l/2 h, oil quenched, tempered at 175 “C (345 “F) for 1 h. Mainly tempered martensite. High austenitizing temperature resulted in some retained austenite (angular white areas) and a few carbide particles. Compare to (c) and (e).
(continued)
432 / Heat Treater’s
Guide
E52100: Microstructures (continued). (g) 4% nital. 4% picral, mixed 1 to 1; 1000x. Same specimen as (f) shown at higher magnification. Dark areas are tempered martensite. Retained austenite (angular light gray areas) is well resolved. A few undissolved carbide particles remain from the original structure (a). (h) 4% nital, 4% picral, 1000x. See (a). Austenitized at 980 “C (1795 “F) for ‘12 h. oil quenched, tempered at 175 “C (345 OF) for 1 h. Coarse plates (needles) of tempered martensite and retained austenite (white). Carbide particles are almost wholly dissolved. (j) 4% nital, 4% picral, mixed 1 to 1; 500x. See (a). Austenitized at 855 “C (1570 “F) for ‘,‘2 h, quenched in a salt bath at 260 “C (500 “F), held for l/s h, air cooled to room temperature. Spheroidal carbide particles in lower bainite, some retained austenite. (k) 4% nital, 4% picral, mixed 1 to 1; 1000x. See (a). Austenitized at 955 “C (1750 “F) for 2 h, cooled slowly to 705 “C (1300 “F), oil quenched. Note dark gray needles of martensite, carbide rejected to grain boundaries (light gray), bainite (black), and retained austenite (small light areas). (m) 4% nital, 500x. Steel rod austenitized at 900 “C (1650 “F) for20 min and slack quenched in oil to room temperature. Dark areas (etched) are a mixture of fine pearlite and bainite. Light areas (almost unetched) are untempered martensite. (n) 4% nrtal. 10 000x. Steel rod, austenitized at 1125 “C (2060 “F) for 15 min, oil quenched. Electron micrograph of a replica rotary-shadowed with chromium. Coarse, untempered martensite. Note cracks in martensite platelets (upper left, upper right). (p) 4?h nital, 5000x. Steel rod, austenitized at 980 “C (1795 “F) for 1 h, quenched in a lead bath at 357 “C (675 “F), held for 2 h. air cooled. Electron micrograph of a replica rotary-shadowed with chromium. Bainite, probably upper bainite. (q) 4% nital, 10 000x. Steel wrre, austenitized at 900 “C (1650 “F) for 30 set, quenched in a lead bath at 530 “C (990 “F), held for 30 set, air cooled. Electron micrograph of a replica rotary-shadowed with chromium. Lamellar pearlite and bainite. (r) 4% nital. 10 000x. Steel rod, austenitized at 1150 “C (2100 “F) for 3 min, quenched in a lead bath at 575 “C (1065 “F), held for 5 min, air cooled. Electron micrograph of a replica static-shadowed with chromium. Fine lamellar pearlite.
Alloy Steel / 433
6118,6118H Chemical Composition. 6118. AK1 and UNS: 0. I6 to 0.2 I C. 0.50 to0.70Mn.O.035 Pma~0.030Smaa.0.15 to0.30Si.0.50to0.70Cr.0.10 too.15 V. UNS H61180and SAE/AISI 6118H: 0.15 too.21 C.O.40 10 0.80 hln. 0. IS to 0.35 Si. 0.40 to 0.80 Cr. 0.10 to 0. IS V Similar
Steels (U.S. and/or
Foreign).
110-l. 5770: (Cer.) DIN I .7S I I. 6118H. 1268: (Ger.) DIN I .75 I I
6118. LINS Ghll80: UNS H6lI80: ASTh1430-l:
WE SAE
Recommended Normalizing.
A chromium-vanadium carhurizing-c~honitriding steel. Its characteristics ‘are approximately the same as thoss for -!I l8H. Because of the slightI> lo\\er clvbon range of 61 l8H. the as-qusnchcd hardness is likely to be lower. spproxmiatel! 36 to 42 HRC. The chromium contents of these tbo steels are nearly the same. and their hardennbilitj hands are nearly the same. The small amount of vanadium contained in 61 l8H acts as a grain refiner and does not increase hardenahility. Is rendilj forgeable and weldable (using allo) steel practice). hlachines reasonaLA> ttell Heat to I245 T (217s “F) maslmum. Do not fwgs after of forging stock drops Mow approximately 900 ‘C ( 1650 ‘F)
6118H: End-Quench Distance from quenched su t-face I‘16 in. mm
Practice
“F). Cool in air
Annealing. Structures ha\ ine best machinability are normally obtained hy normalizing orb! isothermal treatment which consists of heating to 885 “C ( 1625 “FL cooling rapid11 to 690 “C ( 1775 “F). and holding for 4 h tempering process
See recommended carhurizing. carbonitriding. and described for -II l8H. Ion nitriding is an alternative
procedures
Recommended l l l l l
Forging.
Heat to 925 “C (I695
Case Hardening.
Characteristics.
temperature
Heat Treating
l l
Processing
Forge Normalize Anneal (optional) Rough and semifinish Case harden Temper Finish machine
Sequence
machine
Hardenability Hardness, ARC may min
I ;7
I 58 4.71 3 16
46 u38
39 28 36
-I 5 6 7 8 Y I0 II 12
6.32 7.90 Y.-l8 Il.06 12.6-I l-l.11 15.80 17.38 18.96
33 30 28 27 16 26 2s 2s 2-I
2-l 22 ‘0
Distance from quenched surface I‘16 in. mm
Hardness, ERC mas
10.5-l 12.12 23 70 3.28 33 u 31 60 3-l 76 37 92 41.08 4-l 74 -+7.40 50.56
6118, 6118H: Hardness sents an average
based
vs Tempering
Temperature.
on a fully quenched
structure
Repre-
434 / Heat Treater’s
Guide
6150,615OH Chemical
Composition.
6150.AlSIandUNS:0.48to0.53C.0.70
to0.90Mn,0.035Pmax,0.030Sma~.0.15to0.30Si,0.80to1.10Cr.0.15 V min. 6150H.AISland UN& 0.47 to 0.54 C.O.60 to 1.00 Mn.0.035 max. 0.040 S max. 0.15 to 0.30 Si. 0.75 to I.20 Cr. 0. IS V min.
Annealing.
For a predominantly pearlitic structure. heat to 830 “C (I 515 “FJ. cool rapidly to 760 “C ( 1100 “F), then cool to 675 “C (I 235 “F). at a rate not to exceed 8 “C (IS “Fj per h: or heat to 830 “C (1515 “F). cool rapidly to 675 “C (1% “FL and hold for 6 h. For a predominantly spheroidized structure, heat to 760 “C t I100 “F), and cool to 675 “C ( I245 “F) at a rate not to exceed 6 “C (IO “F) per h; or heat to 760 “C (1300 “F), cool rapidly to 650 “C ( I200 “F). and hold for IO h
P
Similar Steels (U.S. and/or Foreign). 6150. UNS G61500; AhlS 6448. 6450, 6455: ASTM A322. A33l: MIL SPEC hlIL-S-8503; SAE J4O-l. J4lL 5770; CrV -I: (Jap.) JIS 47. 6150H. UNS (Fr.) AFNOR 50 SSIJ 2230; (U.K.)
(Ger.) DIN 1.8159; (Fr.) AFNOR 50CV-1: (Ital.) UNI SO SUP IO: (Shed.) SSIJ 2230: (U.K.) B.S. 735 A SO. En. H61500: ASThl A30-I; SAE 5407; (Ger.) DlN I .8159: CV -I; (Ital.) UNI 50 CrV 3; (Jap.) JIS SUP IO: (Swed.) B.S. 735 A SO. En. 37
Characteristics. A medium high-carbon chromium-vanadium allo) steel which has been used for numerous applications including premium quality springs. Its as-quenched hardness is generally 55 to 60 HRC. depending on the precise carbon content. Hardenahilit) is relativeI) high. approximately the same as for -IllOH. The chromium content is main11 responsible for the hardenability. The vanadium serves as a grain refiner and has no significant effect on hardenability. Is forgeable. but is not recommended for helding
Hardening. Tempering.
Reheat immediately after quenching [preferably before the temperature of the parts drops below the range of 38 to 50 “C (100 to I20 “F)] to the temperature required to obtain the desire combination of mechanical properties
Austempering.
For many spring applications. this steel is austempered bq austenitizing at 870 “C t 1600 “F), quenching in an agitated molten salt bath at 3 IS “C (600 “F). holding for I h. and air cooling No tempering is required. Hardness after this treatment generally ranges from approximatslq 16 to 5 I HRC
Recommended l
Forging. temperature
Heat to 1230 “C (2X0 “F) maximum. Do not forge after of forging stock drops below approximately 900 YI. ( 1650 “F)
l l l
Recommended
Heat Treating
Practice
l l
Normalizing.
Heat to 900 “C (I650 “F). Cool in air
6150: Isothermal Transformation C, 0.67 Mn, 0.93 Cr, 0.18 Grain size: 9
Diagram. Composition:
V. Austenitized
at 845 “C (1555
l
0.53
“F).
Heat to 870 “C (1600 OF). and quench in oil
Processing
Sequence
Forge Normalize Anneal Rough machine Austenitize and quench (or austemper) Temper (or austemperj Finish machine
6150: gears
Equipment
requirements
Production requirements H’eight of eclch piece Pieces per furnace load Producuon per hourcaj: Number of pieces Net work load Gross furnace losdr b ) Equipment requirements hlanempering furnace Size of salt pot Capxit) of salt pal -r)peofsdr Quenching sapacrty of ball pot Operating rcmpenture Agitation
for salt mat-tempering
0.9kp(llb, 32 128 116kg(256lb) 152kgt336lb) tmmrnion-heated salt pot(c) 6lOb) 381 by838nun1Xbq lSby33in.) 272kgl6OOlb) Nitrate-nitrite(X acueradded) I81 kg/ht-IGOIb/h) 205 ‘T (400 “R Air-operated stirrer
la1 Clsle ume. IS min. Ib) Work and fikwrrs. Each IYkturz welghed 9.1 kg (20 lb) rmpr) and clzs. 220 c’) used forcooling b> dri\ingroom-rempratureairbewren \rall of pot and exterior shell of furnace
Alloy Steel / 435
6150: Hardness vs Tempering Temperature. Normalized at 900 “C (1650 “F), quenched from 870 “C (1600 “F) in oil, tempered in 56 “C (100 “F) intervals in 13.7 mm (0.540 in.) rounds. Tested in 12.8 mm (0.505 in.) rounds. Source: Republic Steel
6150H: End-Quench Hardenability Distance frum quenched surface 916in. mm 1 2 3 4 5 6 I 8 9 10 11 12
6150:
As-Quenched
Hardness
(Oil)
Single heat results; grade: 0.48 to 0.53 C. 0.70 to 0.90 Mn, 0.20 to 0.35 Si, 0.80 to 1.10 Cr, 0.15 V minimum; ladle: 0.51 C, 0.80 Mn, 0.014P,0.015S.0.35Si,0.11Ni.0.95Cr.0.01Mo,0.18V;grainsize: 5 to 6 for 70%, 2 to 4 for 30% Size round in.
mm
Surface
Hardness, HRC ?(zradius
Center
‘h
13 25 51 102
61 60 54 42
60 58 47 36
60 57 44 35
1 2 4
Source: Bethlehem Steel
1.58 3.16 4.74 6.32 7.90 9.48 11.06 12.64 14.22 15.80 17.38 18.96
Hardness, HRC max min 6.5 65 64 64 63 63 62 61 61 60 59 58
59 58 51 56 55 53 50 41 43 41 39 38
Distance &urn quenched surface 916in. mm 13 14 15 16 18 20 22 24 26 28 30 32
20.54 22.12 23.70 25.28 28.44 31.60 34.76 37.92 41.08 44.24 47.40 50.56
HaIdIlesS, HRC max min 51 55 54 52 50 48 47 46 45 44 43 42
31 36 35 35 34 32 31 30 29 27 26 25
436 / Heat Treater’s
6150: Microstructures.
Guide
(a) 2% nital, 550x. Steel wire, austenitized at 900 “C (1650 “F) for 20 mm and slack quenched in oil to room temperature. Lower bainite (dark) and untempered martensite (light). (b) Picral, 550x. Austenitized at 880 “C (1620 “F) for l/z h, cooled to 730 “C (1350 “F) held 5 h, cooled to 650 “C (1200 “F) at 28 “C (50 “F) per h, held 1 h, air cooled. Pearlite and ferrite. (c) 4% nital, 500x. Steel wire, austenitized at 885 “C (1625 “F) for 20 min, quenched to 675 “C (1245 “F) for 20 min, oil quenched to room temperature. Structure mainly pearlite. (d) 4% nital, 5000x. Steel wire, austenitized at 845 “C (1555 “F) for r/p h, oil quenched, tempered at 150 “C (300 “F). An electron micrograph of a replica rotary-shadowed with chromium. Tempered martensite and some spheroidal carbide particles. (e) 4% nital, 10,000x. Steel wire, austenitized at 870 “C (1600 “F), held for 2 h, quenched in lead to 650 “C (1200 “F), held for 2 h, water quenched. An electron micrograph of a replica rotary-shadowed with chromium. Partly spheroidized carbide in a ferrite matrix. (f) 4% nital, 10,000x. Steel wire, austenitized at 870 “C (1600 “F) for 2 h, quenched in lead to 720 “C (1330 “F), held 2 h, water quenched. An electron micrograph of a replica rotary-shadowed with chromium. Partly spheroidized and partly lamellar pearlite in ferrite. (g) Nital, 535x. Steel rod, 13 mm (l/2 in.) diam, austenitized at 845 “C (1555 “F) for 1 h, quenched to 315 “C (600 “F), held 16 min, air cooled. Mostly bainite, probably lower bainite. (h) Nital, 1000x. Same steel, rod diameter, and heat treatment as (g), except at higher magnification. Austempering was the heat treatment used
Alloy Steel / 437
81 B45,81
B45H
Chemical
Composition. N&15. AISI: 0.43 IO (J.-U C, 0.75 to I .OO hln.0.035 Pmax.O.O-!OSmax.O.lS to0.30Si.0.20to0.10Ni.0.351o0.55 Cr. 0.08 to 0. IS MO. 0.0005 to 0.003 B. UNS: 0.43 to O.-l8 C. 0.75 to 1.00 hIn.0.035 Pmax.O.WOS max.0.15 to0.30Si.0.20 toO.-lONi.0.35 100.55 81BGH: Cr. 0.08 to 0.15 Mo. 0.0005 B min. UNS HSlJSl and SAE/AISI O.-P to 0.19 C. 0.70 to 1.05 Mn. 0.15 to 0.35 Si. 0.15 to O.-IS Ni. 0.30 to 0.60 Cr. 0.08 to 0. IS hlo. B (can be expected to he 0.0005 to 0.003 percent) Similar
Steels (U.S. and/or
ASThl ASl9: SAE J-W. A3O-k SAE J 1268
Foreign).
JAI?. 1770. 81BJ5H.
MB35 UNS
LINS G8l-lS I : H813Sl: ASTM
Annealing.
Forapredominantl\ pearlitic structure. heat to 830°C (IS25 “FJ. cool rapidI) IO 725 “C ( I33S-‘F). then cool to 6-10 “C (I I85 “F). at a rate not to exceed I I ‘C (20 “F) per h; or heat to 830 “C (IS25 “F), cool rapidly to 660 “C t 1220 ‘F). and hold for 7 h. For a predominantly spheroidizsd structure. heat to 750 “C t I380 OF). and cool rapidly to 725 “C t I.335 “F). then continue cooling to 610 “C t I I85 “F) at a rate not to csceed 6 “C (IO “F); or heat to 750 “C ( I380 “F). cool rapidly to 660 “C t I230 “F). and hold for IO h
Hardening. Tempering.
Characteristics.
A slightI> modified version of 86B-iSH. Ni. Cr. and MO are slightly louer. The as-quenched hardnesses of the IWO steels are essentially the same, approaunatel> S-l to 60 HRC. Hardenabilitb of the t\to grades is nearly the same
After quenching. parts should be tempered immediately. Selection of tempering temperature depends upon the desired mechanical propertizs
Recommended l
Forging. temperature
Heat to 1230 ‘C (2250 “F) maxmium. Do not forge after of forging stock drops below approximately 925 “C ( 1695 “F)
l l l
Recommended
Heat Treating
Practice
l l
Normalizing.
Heat to 815 “C t IS55 “F), and quench in oil
Heat to 870 “C t 1600 “FL Cool in mr
81845: Hardness vs Tempering Temperature. Normalized at 870 “C (1600 “F), quenched from 845 “C (1555 “F) in oil, tempered in 56 “C (100 “F) intervals in 13.7 mm (0.540 in.) rounds. Tested in 12.8 mm (0.505 in.) rounds. Source: Republic Steel
l
Processing
Sequence
Forge Normalize Anneal Rough and ssmifmish machine Austenitizs and quench Temper Finish machine
81 B45H: End-Quench Hardenability Distance from quenched surface !&in. mm I 2 3 -I 3 6 7 8 9 I0 II I2
I 58 3.16 4.7-l 6.32 7.90 9.48 I I 06 12.6-l I-I.22 IS.80 17.33 I X.96
Hardness, HRC Olin nlax 63 63 63 63 63 63 62 62 61 60 60 59
56 56 56 56 s5 5-l 53 51 1s 44 II 39
Distance l’rom quenched surface 916 in. mm 13 I-I IS I6 18 20 22 2-I ‘6 18 30 3’
20.5-l 22.12 23.70 3.28 x3.44 31.60 31.76 37.91 41.08 44.2-l 47.40 50.56
Hardness, ElRC max min 58 57 57 56 55 53 52 50 49 -17 45 43
38 37 36 35 34 32 31 30 29 28 28 17
438 / Heat Treater’s
Guide
8615 Chemical
Composition.
8615. AISI and UNS: 0.13 KI 0. I8 C. 0.70
to0.90Mn,0.035Pmrut.0.~0Smax.0.15to0.30Si,0.30to0.70Ni,0.~0 to 0.60 Cr. 0. I5 to 0.25 MO
Similar Steels (U.S. and/or Foreign). LINS G86150; 5333; ASTM A322; ML SPEC MIL-S-866; SAE J4O-%,J770
Tempering. AMS
Characteristics. Similar to 8617H and 8620H. except with a lower carbon range. Extensively used for parts processed by carburizing and carbonitriding. Although there is no published AISI hardenability band for 8615. the hardenability pattern for 8615 should be very similar to that for 8617H. adjusted down slightly because 8615 has a lower carbon range. As-quenched surface hardness for 86 I5 usually ranges from 35 to 30 HRC. Fogeable and weldable: machinability is fairly good Forging. temperature
OF). then holding for 4 h. Another technique is to heat to 790 “C (1455 “F). cool rapidly to 660 “C ( 1220 ‘F). and hold for 8 h
Heat to 1245 “C (2275 “F) maximum. Do not forge after of forging stock drops below approximately 900 “C (1650 “F)
Temper all carburized or carbonitrided parts at I50 “C (300 “F). and no case hardness will be lost as a result. If some decrease in hardness can be tolerated. toughness can be increased by tempering at somewhat higher temperatures, up to 260 “C (500 “F)
Case Hardening. scribed for 8620H. processes
Recommended l l l l
Recommended Normalizing.
Heat Treating Practice
Heat to 935 “C ( I695 OF). Cool in air
Annealing.
Structures nith best machinability malizing or by heating to 885 “C ( 1625 “F). cooling
are developed by norrapidly to 660 “C ( I220
8615: Case Depth of Liquid Carburized Steel vs Time and Temperature. 19 mm (0.75 in.) outside diam by 121 mm (4.75 in.), oil quenched.
l
Carburized
at indicated
temperatures
l l
See carburizing flame hardening
Processing
and carbonitriding and ion nitriding
practices deare alternative
Sequence
Forge Normalize AMY (if required) Rough machine Semitinish machine allowing only grinding stock. no more than IO% of the case depth per side for cart&red parts. In most instances. carboniuided parts are completely finished in this step Carburize or cmbonitride and quench Temper
8615: Liquid
Carburizing. Specimens 19 mm (0.75 in.) by 121 mm (4.75 in.), carburized at 925 “C (1695 “F) for 15 h, air cooled, reheated in neutral salt at 845 o C (1555 “F), quenched in salt at 180 ’ C (355 “F)
8615: Hardness vs Tempering Temperature. average
based
on a fully quenched
structure
Represents
an
Alloy Steel I439
8617,8617H Chemical
Composition. 8617. AISI and UNS: 0. IS to 0.10 C, 0.70 too.90 Mn. 0.035 Pmax. 0.04OS max. 0. I5 too.30 Si.O.10 to0.70Ni.0.40 to 0.60 Cr. 0. IS to 0.25 Mo. UNS H86170 and SAE/AISI 86178: 0. II to 0.20 C, 0.60 to 0.95 Mn. 0. IS to 0.35 Si, 0.35 to 0.75 Ni. 0.35 to 0.65 Cr. 0.15 too.25
Mo
Similar
Steels (U.S. and/or Foreign). 6617. UNS G86170; AMS SAE J-IO-I. 5770; (Ger.) DIN I .6523; (Fr.) AFNOR 20 NCD 2.22 NCD 3: (Ital.) UNI 20 NiCrMo 2; (Jap.j JIS SNCM 21 H. SNCM 21: (U.K.) B.S. 805 H 20.805 M 20.8617H. l[NS H86 170; ASIXI A304 SAE J 1268; (Ger.) DIN 1.6523; (Fr.) AFNOR 20 NCD 3, 22 NCD 2; (Ital.) UN1 20 NiCrhlo 3: (Jap.) JIS SNCM 21 H. SNCM 21; (U.K.) B.S. 805 H 20.805 M 20 6272:
Characteristics.
A carburizing prade of the multiple alloy series. NiCr-Mo. Not as widely used for case hardening as 8620H and 8622H. An as-quenched hardness of approximately 35 to 40 HRC can be expected without carhurizinp. Hardenability is reasonahl) high. Has excellent forgeahility. can he welded using allo) steel practice, and has fair11 good machinability
Forging.
Heat to 1245 “C (2375 “F) malimum. Do not forge after temperature of forging stock drops below approsimately 900 “C ( 1650 “F)
Recommended Normalizing.
Heat Treating
can he tolerated, toughness can he increased higher temperatures. up to 260 “C (SO0 “F)
Heat to 925 “C ( 1695 “F). Cool in air
Annealing.
Structures with hest machinability are developed hj normalizing or hq heating to 885 “C ( I625 “FL cooling rapidly to 660 “C ( I320 “FL and holding for 1 h: or heat to 790 ‘C (l-IS.5 “F). cool rapid11 to 660 “C (I 220 “F), and hold for 8 h.
Tempering.
Temper all carhurized or carbonitrided parts at I SO “C (300 OF) and no loss of case hardness will result. If some dscrease in hardness
at somewhat
Case Hardening. See carburizing and carbonitriding practices described for 8620H. Flame hardemng. ion nitriding. gas nitriding. gas carhurizing, austempering and martempering are alternative processes
Recommended l l l l l
l l
Processing
Sequence
Forge Normalize Anneal (if required) Rough machine Semifinish machine allowinp only 8rinding stock. no more than 10% of the case depth per side for carhunzed parts. Ln most instances. carhonitrided parts are completely finished in this step Carburize or carhonitride and quench Temper
8617: Equipment carburized parts
requirements
Production requirements Weight of load Weight ofeach prece Number of pieces treated per hour
Practice
hy tempering
Equipment
for oil mat-tempering
1S3.6kg(lOOOlbnet) I .S kg f 3.3 lb) 75
requirements
Capacib of quench tank Type of oil
7511 L(2oGOgal) hIineraloil\rithaddjti~est~iscosi~,~SOSUS)
lkmpenturr
I SO “C ( 300 “F) Direct tlow(a,
of oil
Agitation
(a) Agitation pro\ idrd bj I\GO S-hp motors drivmg 457.mm (IS-in.) ‘pm. causing lhc oil to flow at a rate of911 mm/set (36 in./sec)
propellers at 370
8617, 8617H: Hardness vs Tempering Temperature. Represents an average
8617H: End-Quench Hardenability Distance from quenched swtface l/16 in. mm
Hardness, HRC min max
I
I.58
46
2
3.16
4-l
39 33
3
1.11
-II
17
-l
6.32 7.90 9.18
38 3-l 31 28
24 20
5
6 7
Il.06
8
1264 l-l.22 IS.80 17.38 IS.96
9 IO II I2
___
27
26 2s 2-l 23
1::
Distance from quenched surface ‘/lb in. mm I3 I-I IS
I6 I8
20 21 21 26
2o.s-l 22.1’
23.70 25.18 28.4-l 31.60 34.76 37 92
28
41.08 5-1.2-l
30 32
17.40 50.56
Hardness.
HRC max
23 22
‘2 21 II
20
..:
based
on a fully quenched
structure
440 / Heat Treater’s
Guide
8617H: Hardenability
Curves. Heat-treating 925 “C (1700 “F)
(1700 “F). Austenitize:
Hardness purposes I distance, nm 1.5
i ) Ll 13 I5 ‘0 !5 10 $5
limits for specification Hardness, HRC Maximum Minimum 46 44 42 37 32 29 27 25 23 22 20
39 33 27 23 20
.
Hardness limits for specification wrposes I distance, /16mm
, 1;
1
IO I1 12 13 I4 I5 I6 I8 !O !2
Hardness, HRC Maximum Minimum 46 44 41 38 34 31 28 27 26 25 24 23 23 22 22 21 21 20
39 33 27 24 20
temperatures
recommended
by SAE. Normalize (for forged or rolled specimens
only): 925 “C
Alloy Steel / 441
8617: Microstructures.
(a) 1% nital, 500x. 8617H, gas carburized for 3 74 h at 925 “C (1695 “F), cooled in the furnace to 540 “C (1000 “F), air cooled, heated to 840 “C (1545 “F), quenched in oil, tempered for 2 h at 150 “C (300 “F), quenched in oil, tempered for 2 h at 150 “C (300 “F). Numerous microcracks (small black streaks), are present both at the boundaries and across martensite plates. (b) 39/onital. 200x. 8617, carbonitrtded 4 h at 845 “C (1555 “F) in 8% ammonia, 8% propane, remainder endothermic gas, oil quenched, tempered 1 !‘z h at 150 “C (300 “F). Tempered martensite (dark) and retained austenite. (c) 3?L nital, 200x. 8617 steel bar, carbonitrided and tempered same as (b), except held at -73 “C (-100 “F) for 2 h between quenching and tempering to transform most of the retained austenite. Scattered carbide and small amounts of retained austenite in a matrix of tempered martensite. (d) Picral, 200x. 8617 steel bar, annealed by being austenitized at 870 “C (1600 “F) for 2 h, furnace cooled. Fine pearlite (dark) in ferrite matrix (light). Magnification too low for good resolution of structure
Alloy Steel / 441
8620,862OH Chemical
Composition.
8620. AK3 and UNS: Nominal. 0.18
too.23 CO.70 to0.90Mn,0.035 Pmax,O.O40S to 0.70 Ni, 0.40 to 0.60 Cr, 0.15 to 0.25 MO. Nominal. 0.17 to 0.23 C, 0.60 to 0.95 Mn, 0.035 to 0.30 Si, 0.35 to 0.75 Ni, 0.35 to 0.65 Cr, 0.15
max,0.15 toO.3OSi,O.40 862038. AISI and UNS: P max, 0.040 S max, 0.15 to 0.25 MO
Similar Steels (U.S. and/or Foreign). 8620. UNS G86200, AMS 6274,6276,6277; ASTM A322, A33 1, A513, A914; MIL SPEC MIL-S16974; SAE 5126851868; (W. Ger.) DIN 1.6523; (Fr.) AFNOR 20 NCD 2,22 NCD 2; (Ital.) UN1 20 NiCrMo 2; (Jap.) JIS SNCM 21 H, SNCM 21; (U.K.) B.S. 805 H 20,805 M 20.8620H. UNS H86200; ASTM A304; SAE 5407; (W. Ger.) DIN 1.6523; (Fr.) AFNOR 20 NCD 2, 22 NCD 2; (Ital.) UN1 20 NiCrMo 2; (Jap.) JIS SNCM 21 H, SNCM 21; (U.K.) B.S. 805 H 20,805 M 20 Characteristics. Used extensively as a case hardening steel for both carburizing and carbonitriding. As-quenched surface hardness usually ranges from approximately 37 to 43 HRC. Reasonably high hardenability. Excellent forgeability and weldability, although alloy steel practice should be used in welding to minimize susceptibility to weld cracking. Machinability is fairly good. Because 8620H and 8620 are high-tonnage steels, some mills produce them with lead additions. This significantly improves machinability without sacrificing heat treating response
Forging. Heat to 1245 “C (2275 “F) maximum, and do not forge after the temperature of the forging stock has dropped below approximately 900 “C (1650 “F)
Recommended Normalizing.
Heat Treating
Practice
Heat to 925 “C (1700 OF) and cool in air
Annealing.
Structures with best machinability are developed by normalizing or by heating to 885 “C (1625 “F), cooling rapidly to 660 “C (1225 OF), and holding for 4 h. Another technique is to heat to 790 “C (1450 “F), cool rapidly to 660 “C (1225 “F), and hold for 8 h
Carburizing. In general, carburizing practice for 86208 (and 8620) is the same as for other low-carbon, plain carbon, and alloy steels. Because of its inefficiency, the pack method is used only for highly specialized applications. Carburizing by immersion is often used, although mainly for developing relatively thin cases. Any one of a number of proprietary molten salt baths can be used, usually within the temperature range of 870 to 925 “C (1600 to 1700 “F). As a rule, workpieces are quenched directly from the carburizing temperature. 8620H and other carbon and alloy steels are most frequently gas carburized, a far more efficient method that is easier to control
442 / Heat Treater’s
Guide
Gas Carburizing. effectively extensively: l
l
l l
Although a number of different cycles can be used for 8620 and 8620H. the one listed below is a cycle used
Carburize at 925 Y? ( I700 ‘F) in a prepared carbonaceous atmosphere u ith the dewed carbon potential (commonly about 0.90 carbon) for-l h Reduce temperature to g-15 “C ( IS55 “F). reduce carbon potential to near eutectoid. and diffuse for I h Quench in oil Temper for I h at I SC)“C (300 ‘F)
This cycle will result in a total case of approximatslj I.3 mm (0.050 in.). Deeper cases can be obtained with longer cycles. but this is a matter of diminishing returns. Obtaining greater case depths by increasing time cycles IS costly in terms of energy consumption. Case depth can be increased exponsntiallly by increasing the carburizing temperature. but this approach becomes a matter ofeconomlcs as wAl, because the rate ofdeterioration on furnace alloys and refmctories above ahwt 925 “C ( 1700 ‘F) may become intolerable because of the high cost of hmace maintenance. The most economical approach for deep-case carbwizing LSthe use of the vacuum Furnace, which operates as high as 1095 ‘C (2000 “F)
Carbonitriding. For thin, file-hard cases, parts made of 8620 or 8620H are often carbonitrided at g-15 “C ( ISSO ‘F) in a carbonaceous atmosphere with an addition of 10% anhydrous ammonia. Temperatures of 790 to 900 “C ( I-150 to I650 “F) have been used, but 84.5 “C t IS55 “F) seems to be the
most common. Parrs are oil quenched directly from the carbonitriding temperature. Just as is true for carburizing. the case depth increases hith time at temperature. Using a carbonitriding temperature of 845 “C (1555 ‘F). it is possible to obtain a case depth of approximately 0.305 mm (0.012 in.) in about 45 min
Other PrOCeSSeS. ion nitriding, carburiring
Flame hardening. austempering. martempering, gas nitriding ion carburizing. vacuum carburizing. liquid
Tempering.
Temper all carburized or carbonitrided parts at IS0 “C (300 “F) and virtually no loss of case hardness results. If some decrease in hardness can be tolerated, toughness can be increased by tempering at somewhat higher temperatures, up to 260 ‘C (SO0 “F)
Recommended l l l l l
l l
Processing
Sequence
Forge Normalize Anneal (if required) Rough machine Semitinish machine. allowing onl? grinding stock, no more than 10% of the case depth per side for carbunzed parts. In most instances, carbonitridcd parts are completeI> tinished in this step Carburize or carbonitride and quench Temper
8820: Continuous
Cooling Curves. Composition: 0.17 C, 0.82 Mn, 0.31 Si, 0.52 Ni, 0.50 Cr, 0.20 MO. Austenitized at 925 “C (1700 “F). Grain size: 9. AC,, 825 “C (1520 “F); AC,, 745 “C (1370 “F). A: austenite, F: ferrite, B: bainite, M: martensite
Alloy Steel / 443
8620: Isothermal Transformation
Diagram. Composition: 0.18 C, 0.79 Mn, 0.52 Ni, 0.56 Cr. 0.19 MO. Austenitized at 900 “C (1650 “F). Grain size: 9 to 10
8620: End-Quench
8620: Austenitizing
8620: Cooling Time vs Depth of Hardness. Time to cool from
Temperature vs Depth of Hardness. Cast
Hardenability. Composition: 0.18 C, 0.79 Mn, 0.52 Ni, 0.56 Cr. 0.19 MO. Austenitized at 900 “C (1650 “F). Grain size: 9 to 10
RL7911. Heat treatment: A: 900 “C (1650 “F), 15 min. lpsen Furnace; B: 1000 “C (1830 “F), 15 min, lpsen Furnace; C: 1100 “C (2010 “F), 15 min, Muffle and Ipsen. Depth below surface: 1: 0.3 mm (0.012 in.); 2: 2.5 mm (0.1 in.)
730 “C (1350 “F) to temperatures of 540 to 260 “C (1000 to 500 “F), quenched from 845 “C (1555 “F)
8620: Gas Carburizing. Carburized
8620: Liquid Carburizing,
in a recirculating pit furnace. 7.5 h at temperature. 12% CH,. Core: 0.2296 C. 0: 925 “C (1700 “F); 0: 900 “C (1650 “F); A: 870 “C (1600 “F)
Case Hardness Gradients.
tests. Scatter resulting from normal variations
Nine
444 / Heat Treater’s
6620H:
End-Quench Hardenability
Distance from qurnched surface I.‘,6 in. mm I ? 1 4 5 h 7 Y 9 I II II I2
Guide
Hardness. HRC mas min
I .5x 3 Ih 4.7-l h.32 7 90 Y.-IS Il.ufl 12.64 II 12 I5 80 17.38 IX.%
-lx 17 4-l -II 37 34 22 30 ‘9 2x 27 26
6620: End-Quench with theoretical
-II 37 31 27 23 21
_:
Hardenability.
Jominy
results compared
curve (constant H)
6620: Depth of Case vs 0.40% C and 59 HRC. Test specimens 25-mm (l-in.) diam were processed with production gears in a two-row continuous gas carburizing furnace using a diffusion cycle and an atmosphere of endothermic gas enriched with natural gas: air was added to the discharge end. Effective case depth to 50 HRC was measured on a microhardness traverse taken midway between the ends of a cross section of the gear tooth at the junction of the involute profile and root fillet. (a) Depth of case to 0.40% C, 48 tests. 25-mm (l-in.) diam bar tempered in lead at 650 “C (1200 “F). (b) Depth of case to 50 HRC. 47 tests. Gears tempered at 160 “C (325 “F)
6620: Carbon Gradients Produced by Liquid Carburizing. mm (0.75-in.) diam by 51 mm (2 in.), carburized “F) for 8 h
19at 910 “C (1675
6620, 6620H: Hardness vs Tempering Temperature. sents an average based on a fully quenched structure
Repre-
Alloy Steel / 445
8620: Carbon, Nitrogen, and Hardness Gradients. 8620 and 1018 carbonitrided at 845 “C (1555 “F) for 4 h in a batch radianttube furnace. Test data were obtained in a construction-equipment manufacturing plant under normal production conditions, using a standard carbonitriding cycle. Test specimens were carbonitrided in production loads containing 23 kg (50 lb) of gears and shafts. The carbonitriding atmosphere, which was controlled by an infrared control unit, consisted of endothermic gas at 14.1 ma/h (500 fP/h), ammonia at 0.71 m3/h (25 ftVh), propane at 0.01 to 0.02 m3/h (0.25 to 0.75 Wh), and 0.32 to 0.34% CO,. Dew point of the atmosphere was maintained at -7 to - 6 “C (19 to 21 “F) throughout the carbonitridinq cycle. All specimens were quenched from the carbonitriding temperature (845 “C or 1555 “F) in warm (54 “C or 130 “F) oil. (a) Carbon; (b) Nitrogen; (c) Hardness. Quenched in oil at 54 “C (130 “F). Hardness converted from Tukon
8620H: Carbonitriding.
Load: gears, 342 kg (753 lb) net, 459 kg (1011 lb) gross. Batch-type furnace with brick-lined heating chamber, heated by radiant tubes; vestibule-enclosed quench. Dimensions of furnace chamber: 1422 mm wade, 1676 mm long, 1092 mm high (56 by 66 by 43 in.). Garner gas: endothermic gas at 21.2 mVh (750 ft Vh), including 63 min at temperature. Enriching gas: additions of propane at 0.1 m3/h (5 fWh), and of ammonra at 1 .l m3/h (38 ff/h), started after 33 mm at temperature. Generator dew point: -15 to -14 “C (5 to 7 “F) throughout carbonitriding process cycle. Heating chamber pressure: 1.5 to 2.0 mm (0.06 to 0.08 in.) H,O. Carbonitriding temperature: 815 “C (1500 “F). Quenching temperature: 815 “C (1500 “F). (a) Temperature and dew-point variations. (b) resulting carbon gradient
Analysis
of Atmosphere
Near End of Cycle Amount furnace,
Conbtituent
8620:
Approximate
Critical
in 5
Amount \es,tibule,
in B
Points Temperature
Critical
point
OF
T
446 / Heat Treater’s
Guide
8820: Depth of Case After Gas Carburizing.
Depth of case to 0.40% C. 0: Furnace A. 762 by 1219 by 457 mm (30 by 48 by 18 in.). Atmosphere control dew cell with manual reset. Rated gross load, 680 kg (1500 lb). 0: Furnace B, same as Furnace A. A: Furnace C. 914 by 1829 by 610 mm (36 by 72 by 24 in.). Atmosphere control infrared analyzer controlling carbon dioxide, automatic reset. Rated gross load, 1588 kg (3500 lb) (a) 25-mm (1 -in.) rounds carburized at 925 “C (1700 “F) for 1.75 h. Quenched in oil from 845 “C (1555 “F). Diffusion cycle used. Dew points of -15 “C (5 “F) for first part of 925 “C (1700 “F) cycle, -12 “C (10 “F) for diffusion cycle at 925 “C (1700 “F), and -3 “C (27 OF) for time at 845 “C (1555 “F) before quenching. Endothermic plus straight natural gas as enriching gas. Tempered in lead at 650 “C (1200 “F), wire brushed, and liquid abrasive cleaned. (b) 25-mm (l-in.) diam bar. Endothermic with straight natural gas as enriching gas. Carburized at 925 “C (1700 “F), using diffusion cycle. Dew point of -15 “C (5 “F) for 3 h at 925 “C (1700 “F), a dew point of -12 “C (10 “F) for the difl usion portion, and -3 “C (27 “F) for 1 h at 845 “C (1555 “F). (c) 25-mm (1 -in.) diam bar. Total cycle at 925 “C (1700 “F) was 10.5 h, 5 h with a -15 “C (5 “F) dew point, and 5.5 h with a -12 “C (10 OF) dew point. Equalizing time at 845 “C (1555 “F) was 1 h, with a dew point of -3 “C (27 “F). (d) 25-mm (1 -in.) diam bar. Diffusion time with a -12 “C (10 “F) dew point was 6 h. (e) Gears, carburized at 925 “C (1700 “F) in a continuous furnace. (f) 25-mm (1 -in.) diam by 38 mm (1.5 in.), batch-type carburizing
8620H: Gas Carburizing.
Shafts, 171 kg (376 lb), 440 kg (969 lb) gross. Vestibule, enclosed-quench, brick-lined heating chamber, radiant-tube heated. Carrier gas: 21.8 ma/h (770 ff/h) endothermic gas for 5 h 53 min at temperature. Enriching gas: 0.28 m3/h (10 fP/h) propane, 3 h 59 min at temperature (66% of cycle). Generator dew point: 1 to 4 “C (33 to 39 “F). Heating chamber pressure: 2.5 to 3.6 mm (0.10 to 0.14 in.) water column. Carburized at 925 “C (1700 “F) and quenched from 845 “C (1555 “F). (a) Furnace temperature and atmosphere conditions for carburizing. (b) Resulting carbon gradient
Alloy Steel / 447
8620H: Gas Carburizing.
Load: ring gears, 231 kg (510 lb) net, 390 kg (860 lb) gross. Metallic-retort pit furnace, electrically heated. 0.34 m3/h (100 ff/h) endothermic gas throughout the cycle, including 5 h 59 min at temperature. Enriching gas: 0.34 m3/h (12 W/h) natural gas for 2.5 h at temperature (42% of at-temperature cycle). Generator dew point: -6 to -4 “C (22 to 25 “F). Heating chamber pressure: 5.1 to 7.9 mm (0.20 to 0.31 in.), water column. Carburizing temperature: 925 “C (1700 “F). Slow cooled from 925 “C (1700 “F) in cooling pit. Atmosphere at the end of cycle: 20.8% CO, 0.496 CO,, 34.0% H,, 0% O,, 0.8% CH,. (a) Furnace temperature and atmosphere conditions for carburizing. (b) Resulting carbon gradient
8620H: Gas Carburizing.
Ring gears, 231 kg (510 lb) net, 390 kg (860 lb) gross. Metallic-retort pit furnace, electrically heated. 2.83 m3/h (100 fP/h) endothermic gas for 5 h 15 min at temperature, carrier gas. Enriching gas: 0.34 ma/h (12 ftYh) started at temperature and shut off after 3 h (57% of cycle). Generator dew point: -4 to -3 “C (24 to 26 “F). Heating chamber pressure: 8.6 to 11 mm (0.34 to 0.44 in.) water column. Carburized at 925 “C (1700 “F) and slow cooled in cooling pit. (a) Furnace temperature and atmosphere conditions for carburizing. (b) Resulting carbon gradient
8620: Depth of Case vs Time and Temperature. 12-mm (0.5-in.) diam by 6.4 mm (0.25 in.). Carburized at 855 “C (1575 “F), oil quenched, tempered at 150 “C (300 “F), treated at 49 “C (120 “F)
448 / Heat Treater’s
Guide
8620H: Gas Carburizing. Shafts, 145 kg (320 lb) net, 258 kg (569 lb) gross. Metallic-retort pit furnace, electrically heated. Carrier gas: 2.83 mVh (100 fP/h) endothermic gas for 5 h 5 min at temperature. Enriching gas: 0.3 m3/h (9 ff/h) natural gas, for 2 h 50 min from start of cycle (56% of cycle). Generator dew point: 4 to -3 “C (24 to27 “F). Heating chamber pressure: 9.9 to 12 mm (0.39 to 0.49 in.) water column. Carburized at 925 “C (1700 “F) and quenched from 845 “C (1555 “F). (a) Furnace temperature and atmosphere conditions for carburizing. (b) Resulting carbon gradient
8620: Microstructures.
8620: Effect of Carburizing
Time and Temperature. Specimens 19-mm (0.75-in.) diam by 51 mm (2 in.), carburized, air cooled, reheated in neutral salt at 845 “C (1555 “F), quenched in salt at 180 “C (360 “F). (a) Carburized at 870 “C (1600 “F); (b) carburized at 900 “C (1650 “F); (c) carburized at 925 “C (1700 “F)
(a) Picral, 200x. Steel bar normalized by being austenitized at 900 “C (1650 “F) for2 h and cooled in still air. Mixture of ferrite and carbide. Cooling too rapid to produce an annealed structure. (b) Nital, 100x. Steel bar carbonitrided for 4 h at 845 “C (1555 “F), oil quenched, not tempered. and stabilized by subzero treatment. Conventional case structure with martensite, carbide particles, and a small amount of retained austenite. (c) Picral, 1000x. Coarse grain steel, gas carburized 11 h at 925 “C (1700 “F), furnace cooled at 845 “C (1555 “F), oil quenched, tempered 2 h at 195 “C (380 “F). Tempered martensite and retained austenite. A large martensite plate contains several microcracks
Alloy
Steel
/ 449
8820: Microstructures (continued). (d) Picral, 1000x. Same steel, carburizing and heat treatments, and structure as (c), but specimen was subjected to maximum compressive stress of 4137 MPa (600 ksi) for 11.4 million cycles in a contact fatigue test. Butterfly structural alterations developed at microcracks. (e) 4% picral, 500x. Steel gas carburized for 18 h at 925 “C (1700 “F), reheated to 830 “C (1540 “F) and held 40 min, oil quenched, tempered 1 hat 175 “C (350 “F). Nearsurface are grain-boundary oxides and, less visible because of dark etching, bainite and peariite. Remaining structure is carbide particles and retained austenite in a matrix of tempered martensite. (f) Not polished, not etched; 23x. Steel tubing, gas carburized 8 h at 925 “C (1700 “F), hardened, and tempered. Scanning electron micrograph of fractured carburized case. See (g). (g) Not polished, not etched, 1100x. Same as (f), but a higher magnification. Fractured carburized case consists of carbide, retained austenite, and tempered martensite. (h) Not polished, not etched; 23x. Same as (f), except a scanning electron mrcrograph of fractured uncarburized core material (low-carbon martensite). Fracture surface is fibrous. (j) Not polished, not etched; 1100x. Same as (h), but at higher magnification, showing that fractured uncarburized core material has elongated dimples formed dunng transgranular rupture
Alloy Steel / 449
8622,8622H,
862
2RH
Chemical
Composition. 8622. AISI and UNS: 0.20 to 0.25 C, 0.70 to 0.90 Mn, 0.035 Pmax, 0.040 S max, 0.15 to 0.30 Si, 0.40 to 0.70 Ni, 0.40 to 0.60 Cr, 0.15 to 0.25 MO. UNS H86220 and SAE/AISI 8622H: 0.19 to 0.25 C, 0.60 to 0.95 Mn, 0.15 to 0.35 Si, 0.35 to 0.75 Ni, 0.35 to 0.65 Cr, 0.15 to 0.25 MO. SAE 8622RH: 0.20 to 0.25 C, 0.70 to 0.90 Mn, 0.15 to 0.35 Si, 0.40 to 0.70 Ni, 0.40 to 0.60 Cr, 0.15 to 0.25 MO
Recommended
Tempering.
Characteristics.
Case Hardening.
Steels (U.S. and/Or
Foreign).
Except for a slightly higher carbon range, 8622H has an identical composition to 8620H, and the characteristics for 86228 are approximately the same as those for 8620H. Because of the higher carbon range, as-quenched surface hardness is slightly higher for 8622H, approximately 39 to 45 HRC. The hardenability band for 8622H, is adjusted upward just slightly when compared with 8620H. In some carburizing applications, steels that are higher in carbon content have been used to attain a higher core hardness which permits thinner cases. These steels use shorter carburizing cycles and save energy
Forging. Heat to 1245 “C (2275 OF) maximum. Do not forge after temperature of forging stock drops below approximately 900 “C (1650 “F)
Practice
malizing; or by heating to 885 “C (1625 “F), cooling rapidly to 660 “C (1220 “F), and holding for 4 h; or by heating to 790 “C (1455 “F), cooling rapidly to 660 “C (1220 “F), and holding for 8 h
8622. UNS G86220; SAE 5404.5770; (Ger.) DIN 1.6543; (U.K.) B.S. 805 A 20.8622I-I. UNS H86220; ASTM A304; SAE 5407; (Ger.) DIN 1.6543; (U.K.) B.S. 805 A 20
Similar
Heat Treating
Normalizing. Heat to 925 “C (1695 “F). Cool in air Annealing. Structures having best machinability are developed by nor-
Temper all carburtzed or carbonitrided parts at 150 “C (300 “F), and virtually no loss of case hardness will result. If some decrease in hardness can be tolerated, toughness can be increased by tempering at somewhat higher temperatures, up to 260 “C (500 “F) See carburizing and carbonitriding practices described for 8620H. Gas nitriding and ion nitriding are alternative processes
Recommended l l l l l
l l
Processing
Sequence
Forge Normalize Anneal (if required) Rough machine Semifinish machine, allowing only grinding stock, no more than 10% or the case depth per side for carburized parts. In most instances, carbonitrided parts are completely finished in this step Carburize or carbonitride and quench Temper
450 / Heat Treaters
Guide
8822H: Hardenability
Curves. Heat-treating 925 “C (1700 “F)
(1700 “F). Austenitize:
Hardness purposes J distance, mm 1.5 3 5 7 ? I1 13 15 ZO !5 30 35 $0 $5 50
Hardness purposes I distance, VI6in.
,
$ 3 IO I1 12 13 14 15 16 18 20 22 24 26 28 30 32
limits for specification Hardness, HRC Minimum Maximum 50 50 47 43 39 35 32 31 28 26 25 24 24 24 24
43 39 34 28 25 22 20
...
limits for specification Hardness, HRC Minimum Maximum 50 49 47 44 40 37 34 32 31 30 29 28 27 26 26 25 25 24 24 24 24 24 24 24
43 39 34 30 26 24 22 20
temperatures
recommended
by SAE. Normalize (for forged or rolled specimens
only): 925 “C
Alloy Steel / 451
8822RH: Hardenability “C (1700 “F). Austenitize:
Hardness purposes J distance, ‘/,6 in. I -l 3 1 5 b 7 B 9 IQ II 12 IS I-l IS 16 I8 10 12 !-I 16 18 10 32
Hardness purposes I distance, mm I.5
> II
13 I5 !O !S SO $5 u) 15 i0
Curves. Heat-treating 925 “C (1700 “F).
limits for specification Eardness, ARC Maximum Minimum 49 -17 45 II 38 35 32 30 29 28 17 26 25 21 21 23 ‘3 22 22 2’ 22 22 22 21
4-t II 37 32 29 27 2-l 22 21 20
limits for specification Eardness, HRC hlinimum Maximum 49 17 4-l -lo 36 32 30 28 25 23 22 22 22 22 22
4-I -II
36 31
28 2-l 22 20
temperatures
recommended
by SAE. Normalize (for forged or rolled specimens
only): 925
452 / Heat Treaters
Guide
8822, 8622H: Hardness vs Tempering Temperature. Represents an average based on a fully quenched structure
8622H: End-Quench Hardenability Distance from quenched surface '/,6 in. mm
I 7 ; -1 5 6 7
8 Y I0 II 12
Hardness, HRC max min
Distance from quenched surface l/l6 in. mm
Hardness,
HRC man
I.58
SO
13
I3
20.54
27
1.71 3.16 6.32 7 90 9.48 I I.06 126-l I-1.22 15.80 17.38 18.96
17 49 4-l 10 37 3-l 32 31 30 29 ‘8
3-l 39 30 26 21 21 20
I5 II I6 I8 20 22 24 26 28 30 31
x.12 23 70 25 28 284-I 31.60 31.76 37.92 -I I .08 J-l.21 47.4) 50.56
26 25 25 2-l 2-l 2-l 2-l 2-l 2-l ‘-I
452 / Heat Treaters
Guide
8625,8625H Chemical
COIIIpOSitiOn. 8625. AISI and UNS: 0.23 to 0.33 C. 0.70 toO.90 hln. 0.035 Pmas. O.O-!OS max.0.1.5 toO.3OSi. 0.30 too.70 Ni.O.10 to 0.40 Cr. 0. IS to 0.3 hfo. UNS H86250 and SAE/AISI 86258: 0.22 to 0.28 C. 0 60 to 0.95 hln. 0.15 to 0.35 Si. 0.35 to 0.7s Ni. 0.3s to 0.65 Cr. 0. IS to 0.3 hlo
Similar
Steels (U.S. and/or Foreign).
SPEC hllL-S-16974: A304 SAE J I’68
SAE 1104. 1770. 86258.
8625.llNS 686250: hill 1rNS H842SO: ASTM
Characteristics.
Identical to 86ZOH swept for higher carbon range. Hhich results in a higher as-quenched hardness (approsimately -IO to 46 HRC). and some\\ hat higher hardenabilitl. Case hardening by carburizinp or carbonitriding are the heat treatments most often used. Has come into more extensive use to sa\e energy in carburirinp. Weldable. but alloy steel welding practice must be used
Annealing.
Structures ha\ ing best machinability are developed by normalizing; or bl heating- to 885 “C ( 1625 “F). cooling rapidly to 660 “C ( I220 “FL and holding tor -I h: or by heating to 790 “C ( 1455 “F). cooling rapidly to 660 jC t 1220 “F). and holding for 8 h
Tempering.
Temper all carburized or carbonitrided parts at IS0 “C (300 “F). and virtualI) no loss of case hardness will result. If some decrease in hardness can be tolerated, toughness can be increased by tempering at someu hat higher temperatures. up to 260 “C (SO0 OF)
Case Hardening. See carburizing and carbonitriding practices described for 862OH. Ion nttridinp and gas mtriding are alternative processes
Recommended l l l
Forging.
Heat to 1315 “C (2775 “F) maslmum. Do not forge after temperature of forging stock drops belot+ appro\imatel> 900 “C ( 1650 “F)
Recommended
Heat Treating
l l
Practice l
Normalizing.
Heat to 915 ‘C ( IhYS ;F). Cool in air
l
Processing
Sequence
Forge Normalize Anneal (ifrequired) Rough machine Ssmkinish machine. allo\\ing. only grinding stock. no more than IO% of the case depth per side for carbuhzed parts. In most instances. carbonitrided p‘artutswe completely finished in this step Carbunze or carbonitride and quench Temper
Alloy Steel / 453
8625: Hardenability
Curves. Heat-treating
(1650 “F). Austenitize:
iardness w-poses distance, qm
.5
1 3 5 :0 :5 IO I5 Kl 15 i0
iardness wrposes distance,
‘16in.
.O 1 2 3 4 5 6 8 !O !2 !4 !6 !8 IO 12
870 “C (1600 “F)
limits for specification Badness, HRC Maximum Minimum 52 51 48 45 41 38 35 33 29 28 21 26 26 26 25
45 40 35 31 28 25 23 21
limits for specification Hardness, HRC hlahum hlinimum 52 51 48 46 43 40 31 35 33 32 31 30 29 28 28 27 27 26 26 26 26 25 25 25
45 41 36 32 29 21 25 23 22 21 20
.
temperatures
recommended
by SAE. Normalize
(for forged or rolled specimens
only): 900 “C
454 / Heat Treaters
Guide
8625, 8625H: Hardness vs Tempering Temperature. Represents an average based on a fully quenched structure
8625H: End-Quench Hardenability Distance From quenched surface ‘/,6 in. mm I
Hardness, ERC min maw
Distance from quenched surface ‘/,6 in. mm
HidlleSS,
HRC max
IO
1.58 3.16 J.74 6.32 7.90 9.48 Il.06 12.64 14.22 15.80
52 51 18 46 43 10 37 3s 33 32
45 -II 36 37 29 27 2s 23 22 21
IS I3 IS lb 18 20 22 2-l 26 28
20.5-I 22.12 13 70 3.18 28.4-I 31.60 31.76 37.92 4108 44.2-I
29 38 28 27 27 26 26 26 26 2s
II I2
17.38 18.96
31 30
20
30 32
47.10 50.56
2s 75
2 3 -I 5 6 7 8 9
454 / Heat Treaters Guide
8627,8627H Chemical
COIIIpOSitiOn. 8627. AISI and UNS: 0.25 to 0.30 c. 0.70 to0.90Mn.0.03SPmax.0.030Smax,0.lSto0.30Si,0.~0to0.70Ni.0.~0 to 0.60 Cr. 0. I5 to 0.25 Mo. UNS A86270 and SAE/AISI 86278: 0.24 to 0.30 C. 0.60 to 0.95 Mn. 0.15 to 0.35 Si, 0.35 to 0.75 Ni. 0.35 to 0.65 Cr. 0. IS to 0.25 MO
‘F) per h; or heat to 760 “C ( l-t00 “F). cool rapidly and hold for 8 h
Direct Hardening. Tempering.
Austenitize
to 665 “C (I 230 “F),
at 870 “C (1600 “F), and quench in oil
After direct hardening. After quenching. to provide the desired hardness
reheat to the tem-
Similar Steels (U.S. and/or Foreign). 8627.llNS G86270; ShE
perature required
J-IO-L J770.86278.
and carbonitriding practice deCase Hardening. See carburizing scribed for 8620H. Ion nitriding and gas nitriding are suitable processes
LINS H86270:
ASTM
A3O-t; SAE J I268
Characteristics. Has a borderline composition. with a carbon content near the maximum used for case hardening. but at ahout the minimum suitable for direct hardening. Used for both as demanded. however. Asquenched surface hardness of approximately 12 to 38 HRC can be expected. Hardenability band for 8627H is slightly higher than for 862SH Forging. Heat to 1230 “C (2250 “F) maximum. Do not forge after temperature of forging stocb drops below approximately 900 “C ( I650 “F). For direct hardening, see tempering curve
Tempering.
After case hardening. Temper all carburized or carbonitridsd parts at I SO “C (300 “F). and Gtually no loss of case hardness will result. If some decrease in hardness can be tolerated, toughness can be increased hy tempering at somen hat higher temperatures. up to 260 “C (500 “F). For direct hardening, see tempering curve
Recommended l
Recommended Heat Treating Practice Normalizing. Heat to 900 “C (I650 “FL Cool in air Annealing. For a predominantly pearlitic structure. heat
to 8-0 “C (I 555 “F). cool rapidly to 730 “C ( I350 “F), then cool to 6-10 “C ( I I85 “F). at a rate not to exceed I I “C (20 “F) per h: or heat to 815 “C (15% “F). cool rapidly to 665 “C (I230 “F). and hold for 6 h. For a predominantly spheroidized structure, heat to 760 “C ( l-t00 “F). cool rapidly to 730 “C I I350 “Fj, then cool to 650 “C ( I200 “F). at a rate not to exceed 6 “C ( IO
l l l l
l l l
Processing
Sequence
Forge Nomralize Anneal (if required) Rough machine Semitinish machine. allo~iing only grinding stock, no more than 10% of the case depth per side for carburized parts. In most instances, carbonitrided parts are completely tinished in this step Case harden or direct harden Quench Temper
Alloy Steel / 455
8627H: Hardenability (1650 “F). Austenitize:
Hardness purposes J distance, mm 1.5
2
I1 13 15 20 25 30 35 40 45 50
Hardness purposes I distance, !iSill.
i 4 ) 10 II
12 13 14 15 16 18 20 !2 24 26 28 30 32
Curves. Heat-treating 870 “C (1600 “F)
limits for specification Aardness, Maximum
ARC hbimum
47 43 38 34 31 21 25 24 21 20
54 53 50 41 44 41 38 35 32 30 28 27 27 27 27
limits for specification Hardness, Maximum
54 52 50 48 45 43 40 38 36 34 33 32 31 30 30 29 28 28 28 21 27 27 21 21
q RC hGtknum 47 43 38 35 32 29 27 26 24 24 23 22 21 21 20 20
. .
temperatures
recommended
by SAE. Normalize (for forged or rolled specimens
only): 900 “C
456 / Heat Treaters
Guide
8627, 8627H: Hardness vs Tempering Temperature. Represents an average based on a fully quenched structure
8627H: End-Quench Hardenability Distance From quenched ‘surface I 16in. mm
Hardness. HRC mm min
Distance From quenched iut-race ‘.&ill. mm
Hardness. HRC nlas min
456 / Heat Treaters
Guide
8630,863OH Chemical Composition. 8630. MS1 and UNS: 0.28 to 0.33 C. 0.70 IO (J.90 hln. 0.035 P mxs. 0.010 S ma\. 0. IS to 0.30 Si. 0.10 to 0.70 Ni. 0.40 to 0.60 Cr. 0. IS to 0.15 hlo UNS H86.300 and SAE/AISI 86308: 0.27 to 0.33 C. 0.60 to 0.95 hln. 0.15 to 0.35 Si. 0.3.i to 0.75 Ni. 0.35 to 0.65 Cr. 0. IS to 0.25
Similar
hlo
Steels (U.S. and/or Foreign).
863O.llNS G86300: AhlS
6280. 6% I. 635s. 6530. 6550: ASThl ,432 A?? I : MlL SPEC hlIL-S1697-l; SAE J-IO-t. J-II?. 5770: tGsr.) DIN l.hS-lS: tltnl.) UNI 30 NiCrhlo 2 KB. 8630H. 1lNS H86300: ASThl A.301: S.4EJ 1268; tGer.) DIN I.6S-lS. tltal.) 1lNl 30 NiCrhlo 2 KE3
Characteristics.
A medium-carbon steel. Responds rendil> to direct hardening. As-quenched surfxe hardness usunlly ranges from npproximateI, -t6 to S2 HRC Its hardennhilit> band is s~milur IO other 86XXH steels. Seldom used tor case hardening h> curburirinq or carbomtridinp hecause of its carbon content. Genernll~ a\ ailahle in various product forms mcluding seamless tubing used in productne \\elded structures. Forges ensil! rmd can he melded hy virtually an\ of the \rell-knwn techniques. Because of its relattvel~ high hardenahtltt~. allo) steel practtce must he used in welding
Forging. temperature
Hent to 1230 “C t22SO “F) maximum. Do not forge after of forging stock drops MOM approximateI> 900 “‘C i I650 “F)
Recommended Normalizing.
Heat Treating
Practice
Heat to 900 “C t IhSO ‘F). Cool in air. In aerospace practice. parts are normalized 3: 000 ‘C I I650 “F)
Annealing. For a prsdonunantl~ psxlitic structure. heat to 835 “C t IS55 “FI. cool rapidly to 730 “C t I3SO “F). then cool to 610 “C t I I80 “F). at a rate not to exceed I I “C t 20 “F) per h: or heat to X-0 “C f IS55 “F). cool rupidl> to 66s ‘C t I230 “FI. and hold for 6 h. For a predominantly spheroidtzed \tructure. heat to 760 ‘C t l-IO0 ‘F). cool rapidly to 730 “C I I350 “F). then cool to 650 “C t I200 “F). at a rate not to exceed 6 “C t IO “FJ per h: or heat to 760 “C t l-IO0 “F). cool rapidly to 665 ‘C I I230 “F). and hold for 8 h In aerwpuce pmcoce. parts are unnsalsd at 84S jC t IS55 “F). then cooled to below S-IO“C I I(NHI “F) at ~1mte not to exceed 95 ‘C (205 “F) per h Hardening. Austenitire at 870 “‘C I 1600 “F). and quench in oil. Flame hardeninp. _eas nitridinp. ion nitriding. carhonitriding. and martemperinp are alternattve processes. Qusnchunts include \\uter and polymers. In aerospace practice. austsmtize at XSS ‘YY t IS70 “F). and quench in oil or poll mer Tempering. providing
*After quenchtng. reheat to the temperature required the desired hardness or other mechanical properties
Recommended
Processing
Forge Nomlalize >\MtXll
Rough and semifinish machine Austenitize and quench Temper Finish machine
Sequence
for
Alloy Steel / 457
8630H: End-Quench Hardenability Distance from quenched surface ‘/lb in. mm I 7 ; -I s 6 7 8 9 I0 II II
8630:
I..58
Distance from quenched surface l/16 in. mm
Eardness. HRC may min
Hardness. HRC min mas
43 71 16
S6 55 54
-19 46 -1.3
IS I-l 15
20.5-l 22.12 23.70
33 33 3’
23 2). 77
6.31 7.90 9.48 II.06 12.64 I-l 22 15.80 17.38 18.96
52 50 47 4-l II 39 37 3s 31
39 ss 32 29 28 17 26 ‘9 2-l
16 18 20 ‘2 ‘-I ‘6 28 SO 32
25.28 2X.44 31 60 34.76 37 92 11.08 J-l.24 47 40 SO.56
;; 30 30 29 29 29 29 29 3
I; 21 20 20
Approximate
Critical
Points
8630: End-Quench
Temperature Critical point
“C
OF
735 795 71s 660
I?SS 1460 1370 I220
Hardenability. Composition: 0.30 C, 0.80 Mn, 0.54 Ni. 0.55 Cr, 0.21 MO. Austenitized at 870 “C (1600 “F). Grain size: 9
8630: Isothermal Transformation
Diagram. Composition: 0.30 C, 0.80 Mn, 0.54 Ni. 0.55 Cr. 0.21 MO. Austenitized at 870 “C (1600 “F). Grain size: 9
458 / Heat Treaters
Guide
8630: Continuous Cooling Transformation Austenitized
8630:
Diagram. Composition:
0.30 C, 0.80 Mn, 0.020 P, 0.020 S, 0.25 Si, 0.55 Ni, 0.50 Cr, 0.20 MO.
at 850 “C (1560 “F)
Effect of Heat Treatment
Hent treatment
H’ater quenched from 84.i ‘C I IS55 “FL rempered ~~180°C (900 “FI \\aslerquenchrd from 84S ,‘C I ISSS FL kmpered at 5-M) “C I IO(w) ‘FI \Varer quenched from 845 ’ C I I SSS “FL wmperedat 5% “Cc I IOO’F,
‘/z in. (13 mm)
8630: Suggested Practice)
on Hardness Size round measured in 2in. I In. Jill. (2Smm) (51 mm) (IO2 mm)
201 302
IS6 I87 3.1
I87 269
I87 235
2Yi
269
23.5
217
269
211
227
I97
620-860 hlPa (!JO-125ksi) I I ) 650 C I l~(N)‘l=~ 1216fiO’C ~12iO”F1 I
ca~HeatrdwWS”C~ 1555‘~F~.iuma~ecoolsda~ I I “C~2O”F~p~rhour1062S “CI I ICS ,F). cooled in ar. fb) Hrnred to 870 “C ( I600 “FL cooled in air. Source: Rrpuhtic Sttxl
I ,Qusnsh
Tempering
Temperatures
(Aerospace
Tensile strength range 865-1035 hlPa 1035-1175 MPa 1175-1210 MPa IWO-1380 MPa (12515Oksi) (1%17Oksi) (17048Oksi) (MI-200 ksi) sso ,‘C I 103 ‘F, 5.50 “C I 1025 “FI
In ml orpol!mrr.
185 “C (905 “F1 510°C 1950 -FI
-l-lo (825 -l-lo (825
“C “FJ “C “FJ
121 C)uench in skater Source: AhlS 2759/l
370 “C (700°F) 370 “C (700 “Fj
Alloy Steel / 459
8630H: Hardenability Curves. Heat-treatinq (1650 “F). Austenitize:
iardness wrposes I distance, nm 1.5
)
I1 13 15 !O !5 !O I5 K.l 6 i0
iardness wrposes distance,
‘16io.
0 1
2 3 4 5 6 8 0 2 4 6 8 0 2
870 “C (1600 “F)
limits for specification Hardness, Maximum
HRC Minimum
49 46 42 38 33 29 27 26 23 21 20 .
56 55 54 51 48 44 41 38 34 31 30 29 29 29 29
limits for specification Hardness, HRC hlaximum
56 55 54 52 50 47 44 41 39 37 35 34 33 33 32 31 30 30 29 29 29 29 29 29
Minimum
49 46 43 39 35 32 29 28 21 26 25 24 23 22 22 21 21 20 20
temperatures -
recommended
by SAE. Normalize (for forged or rolled specimens
only): 900 “C
460 / Heat Treaters
Guide
8830: Hardness vs Tempering Temperature. Composition: 0.28 to 0.33 C, 0.70 to 0.90 Mn. 0.20 to 0.35 Si, 0.40 to 0.70 Ni, 0.40 to 60 Cr. 0.15 to 0.25 MO. Forged at 1230 “C (2250 “F). Normalized at 900 “C (1650 “F). Furnace cooled from 815 to 870 “C (1500 to 1600 “F). Tempered 2 h. Maximum annealed hardness, 179 HB. Hardness normalized in test size, 225 HB. Source: Republic Steel
460 / Heat Treaters
Guide
86B30H Chemical
Composition.
SAE/AISI 86B30H:o27 KI 0.33 c.O.60
to0 95 hln.0.035 Pmas.O.040S ma\.O.lS to0.30Si.O.3S too.75 Ni.0.35 to 0.65 Cr. 0.1.5 to 0.5 MO. O.OOOS to 0.003 B. UNS H86301 and SAE/AISE 86B30H: 0.27 to 0.33 C. 0.60 to 0.95 hln. 0. IS to 0.3s Si. 0.35 to 0.75 Ni. 0.35 too.65 Cr.0.15 to025 hlo. B (can beexpected to heO.OOOS to 0.003 percent 1
Similar
Steels (U.S. and/or Foreign).
UNS
G863OI:
ASThl
.A?W; S,-IE J 1268
Annealing.
For a predominantly pearlitic structure, heat to 8-15 “C (I 555 “F). cool &a I! to 730 “C t 1350°F~ then cool to 610 “C (I I85 “F). at a rate not to exceed I I ‘C (20 ‘F) per h; or heat to 8-U “C (IS55 “F), cool rapid11 to 66s “C t I230 “F). and hold for 7 h. For a predominantly sph?roidized structure. heat to 760 “C t 1100 “F). cool rapidly to 730 “C t I?0 “F). then cool to 650 ‘C ( I200 jF). at ;L rate not to exceed 6 “C ( IO “‘FJ per h; or heat to 760 ‘C I 1400 ‘F). cool rapidly to 665 “C (I 230 “F), and hold for IO h
Hardening.
Characteristics. Identical in composition to 8630H \\ ith boron added. The applications of 86830H are also 5inilx to those for 8630H. 86B?OH ib selected for ik+ increased hurdsnnbilit!. 1%hich IS a result of the horon addition. As-quenched surfxe hardnecs of86B3OH generally ranges from 46 to S1_ HRC. about the same as for 8630H. Forging and heat trenting prwedure3 for 86B30H are essential11 the same a\ those used for X630H
hardening. processes
Tempering. the tempemture
Forging.
Heat to I230 “C (2250 “FI maximum. Do not forge after of forging stock drops below approximateI> 92s ‘C t I695 “F,
l l l
Recommended
Heat Treating
Practice
l l
Normalizing.
Heat to 900 “C t 16.50 “‘FL Cool in uir
l
at 870 “‘C t 1600 “F). and quench in oil. Flame cxbonitriding. and ion nitriding anz suitable
Parts should be tempered immediateI) after quenching which u ill pro\ ids the requued hardness
Recommended l
tcmpersturc
Austenitire pas nitridinp.
Processing
Sequence
Forge Normalize ,kineal Rough and semifinish machine Austenitizr and quench Temper Finish machine
86B30H: Hardness vs Tempering Temperature. average based on a fully quenched structure
Represents
an
at
Alloy Steel / 461
88630H: Hardenability
Curves. Heat-treating
“C (1650 “F). Austenitiie:
870 “C (1600 “F)
iardness wrposes I distance, nm 1.5 \ i 1 9 I1 13 15 20 z5 30 35 40 15 50
limits for specification Eardness, HRC hlaximum hliuimum 56 56 55 55 54 54 53 53 52 50 48 46 43 41 40
49 49 48 48 48 47 46 44 39 35 33 30 28 27 25
iardness limits for specification Burposes distance, \6 in.
0 1 2 3 4 5 6 8 .O :2 !4 16 !8 IO I2
Hardness. ERC Maximum hlinimum 56 55 55 55 54 54 53 53 52 52 52 51 51 50 50 49 48 41 45 44 43 41 40 39
49 49 48 48 48 48 48 47 46 44 42 40 39 38 36 35 34 32 31 29 28 21 26 25
temperatures
recommended
by SAE. Normalize
(for forged or rolled specimens
only): 900
462 / Heat Treaters
Guide
86B30H: End-Quench Hardenability Distance from quenched surface 146h. mm 1
1.58
2 3 4 5 6
3.16 4.14 6.32 7.90 9.48
7
11.06
8 9
12.64 14.22 15.80
10 11 12
17.38 18.96
Hardness, HRC max min 56 55 55 55 54 54 53 53 52 52 52 51
49 49 48 48 48 48 48 41
46 44 42 40
Distance from quenched surface ‘/lb in. mm 13 14 15 16 18 20 22 24 26 28 30 32
20.54 22.12 23.70 25.28 28.44 31.60 34.76 37.92 41.08 44.24 47.40 50.56
Hardness, HRC mar min 51 50 50 49 48 41 45
44 43 41
40 39
39 38 36 35 34 32 31 29 28 27 26 25
8637,8637H Chemical COrTIpOSitiOn. 8637. AISI and UNS: 0.35 to 0.40 C, 0.75 to 1.00 Mn. 0.035 Pmax. 0.040 S max. 0.15 to 0.30 Si, 0.40 to 0.70 Ni, 0.40 to 0.60 Cr. 0.15 to 0.25 MO. IJNS II86370 and SAE/AISI 8637I-I: 0.34 to 0.41 C, 0.70 to 1.05 Mn, 0.15 to 0.35 Si, 0.35 to 0.75 Ni, 0.35 to 0.65 Cr, 0.15 to 0.25 MO Similar
Steels (U.S. and/or
J404,J412.J770.8637H.
Foreign). 8637. UNS G86370; SAE UNS H86370; ASTM A304; SAE 51268
Characteristics. A medium-carbon, low-alloy steel, which is widely used for a variety of machinery components because of its ability to be heat treated for high strength and toughness. Used for shafts requiring high fatigue strength. Amenable to nitriding for resistance to surface wear and for greater fatigue strength. As-quenched surface hardness ranges from 50 to 55 HRC. Its hardenability is considered fairly high. Is readily forged
“F) per h; or heat to 750 “C (1380 “F), cool rapidly to 665 “C (1230 “F), and hold for 8 h
Direct Hardening. Tempering.
After quenching, reheat immediately to the tempering temperature that will provide the desired combination of mechanical properties
Nitriding. Responds well to ammonia gas nitriding as well as to nitriding in any one of several proprietary molten salt baths. The following is a commonly used cycle for ammonia gas nitriding: l
l l
Forging.
Heat to 1230 “C (2250 “F) maximum. Do not forge after temperature of forging stock drops below approximately 900 “C (1650 “F)
Recommended Normalizing.
Heat Treating
Practice
Heat to 870 “C (1600 OF). Cool in air
For a predominantly pearlitic structure, heat to 830 “C (1525 “F), cool rapidly to 725 “C (1335 “F), then cool to 640 “C (1185 “F), at a rate not to exceed 11 “C (20 “F) per h; or heat to 830 “C (1525 “F), cool rapidly to 665 “C (1230 OF), and hold for 6 h. For a predominantly spheroidized structure, heat to 750 “C (1380 “F), cool rapidly to 725 “C (1335 “F), then cool to 640 “C (1185 “F), at a rate not to exceed 6 “C (10
Parts are austenitized, quenched, and tempered at 540 “C (1000 “F) or higher. (Tempering temperature must always be higher than the nitriding temperature) Finish machine Nitride in ammonia gas for 10 to 12 h with an ammonia gas dissociation of 25 to 30%
See processing data for 4140H for other nitriding cycles
Recommended l l
Annealing.
Austenitize at 855 “C (1570 OF), and quench in oil
l l l l l l
Processing
Sequence
Forge Normalize Anneal Rough and semilinish machine Austenitize and quench Temper Finish machine (grind if required) Nitride (optional) 8637, 8637H: Hardness vs Tempering Temperature. sents an average based on a fully quenched structure
Repre-
Alloy Steel / 463
8637H: Hardenability
Curves. Heat-treating temperatures 845 “C (1555 “F)
(1600 “F). Austenitize:
iardness wrposes I distance, nm .5 ! i 1
a 1 3 5 !O !5 10 15 10 15 i0
Hardness purposes J distance, %ain. I 2 3 4 5 5 7 5 J IO I1 12 3 14 .5 ‘6 .8 !O !2 ,4 !6 !8 50 12
limits for specification Hardness, HRC Minimum Maximum 59 59 58 57 55 54 52 50 45 41 38 36 35 35 35
52 51 49 47 43 39 36 33 29 21 25 24 24 23 23
limits for specification Hardness, HRC Minimum Maximum 59 58 58 51 56 55 54 53 51 49 47 46 44 43 41 40 39 37 36 36 35 35 35 35
52 51 50 48 45 42 39 36 34 32 31 30 29 28 21 26 25 25 24 24 24 24 23 23
recommended
by SAE. Normalize (for forged or rolled specimens
only): 870 “C
464 / Heat Treaters
Guide
8637H: End-Quench Hardenability Distance from Hardness, HRC max min 1 2 3 4 S 6 7 8 9 10 11 12
1.58 3.16 4.74 6.32 7.90 9.48 11.06 12.64 14.22 15.80 17.38 18.96
59 58 58 57 56 55 54 53 51 49 47 46
52 51 50 48 45 42 39 36 34 32 31 30
Distance from quenched surface mm 516 in. 13 14 15 16 18 20 22 24 26 28 30 32
20.54 22.12 23.70 25.28 28.44 31.60 34.76 37.92 41.08 44.24 47.40 SO.56
Hardness, HRC max min 44 43 41 40 39 37 36 36 35 35 35 35
29 28 27 26 25 25 24 24 24 24 23 23
464 / Heat Treaters
Guide
8640,864OH Chemical Composition. 8640. MS1 and UN.9 0.38 to I .OO hln. 0.035 Pmw.. O.(J-lOS max. 0. IS to 0.30 Si. 0.40 to 0 60 Cr. 0. IS to 0.25 hlo. 86JOH. MS1 and LJNS: 0.37 IO I.05 hln.0.0.35 Pmw O.O-!OS max.O.lS to0.3OSi.0.35 to 0.65 Cr. 0. IS to 0.25 hlo Similar
Steels (U.S. and/or Foreign).
to 0.43 C. 0.75 to 0.70 Ni.O.41 to 0.4-I C. 0.70 toO.7S Ni.0.35
l
l l
1lNS G864OO: ASThl A3O-l. A32 hllL SPEC hllL-S-l6974 SAE 140-I. J412. 5770: t&r., DIN 1.6546; (Ital.) LINI 40 NiCrhlo 2 KB: tL1.K.) B.S. Type 7. g&OH. 1lNS H86-W: 4SThl MO-k SAE J-107: tGer. ) DIN I .6546; t Ital. I LINI 40 NiCrMo 2 KB: tL1.K.) B.S. Type 7 8640.
Characteristics. Probably the most u idsI! used medium-c&on. IOH allo) steel. A~ailnhls tn various product fomls. Can be heat treated to high values of strength and toughness and. if desired. can btt nitrided to achie\ e wrfxe.; that help to resist abrasion and furtha increase fatigue strength. Depending on the precise carbon content. an as-quenched surface hardwss of approximately 52 to 57 HRC can be expected. Hardrnnbilitj is rslati\4> high. Can he forged by an! one of thz various forging methods
of
2s
to 3oc
SW processuy
data for 4 I-IOH for other nitriding qcles
Recommended l l l l l l l l
Forging.
Parts xs austenitired. qwnched. and tsmpered at S-IO “C (1000 “F) or higher. (Tempering temperature must nl~aqs be higher than tht nitriding tsmpsraturs t Finish machine Nitride in ammonia gas for IO to 12 h u ith an ammonia gas dissociation
Processing
Sequence
Forge Normalize Anneal Rough and senitinish machine Auhtrnitiz? and qurnch Ttmpcr Finish machine cgnnd if rzqulred) Nitride (optional)
Heat to 1230 “C cYS(J “F) m;Ixm~um. Do not forge after temperature of forging stozh drops MOM sppro\imatsl> 900 “C ( I hS(J “F,
Recommended Normalizing.
Heat Treating
Practice
Hzat to 870 “C t 1600 “FL Cool in air
Annealing. Far a predominantI! psnrlitlc struuctur~. heat to 830 “C t IS25 “FL cool rapidI) to 725 ‘C t I335 “FL then cool to 640 “C t I I85 ‘F). at a rate not to exceed I I ‘C (20 “F) per h: or heat to 830 “C ( IS25 *FJ. cool rapidly to 665 “C (I230 “FL and hold for 6 h. For a predominantI> spheroidixd structure. hat to 750 “C t 1380 “‘FI. cool rapid11 to 725 “C t 133.5 “FL then cool to 640 YI ( I I85 “FL at a rate not to csceed 6 “C t IO ‘F) per h: or htat to 750 “C t 1380 ‘FL cool rapid11 to 665 “C I 1230 “F). and hold for 8 h Hardening.
Austenitlzc
at MS “C t IS70 ‘FL and quench in oil
Tempering. pcrrltun
After quenchinp. reheat imnwdiatcl~ to th? tempenng trmthat will provide the deswd combination o~mschanicnl properttss
Nitriding. Responds HA to ammonia gas nitridinp as well as to nitriding in any one of szvcral proprietary molten salt baths. Ths following is a commonI) used cycle for ammonia gas nitriding:
8640: Hardness vs Diameter. Composition: 0.38 to 0.43 C, 0.75 to1.00Mn,0.040Pmax.0.040Smax,0.20to0.35Si,0.40to0.70 Ni. 0.40 to 0.60 Cr, 0.15 to 0.25 MO. Test specimens were normalized at 870 “C (1600 “F) in over-sized rounds, quenched from 845 “C (1555 “F) in oil in sizes shown, tempered at 540 “C (1000 “F). Tested in 12.8 mm (0.505 in.) rounds. Tested from bars 38 mm (1.50 in.) diam taken at half radius position. Source: Republic Steel
Alloy Steel / 465
8840: Continuous
C oling Curves. Composition: 0.37 C, 0.67 Mn, 0.25 Si, 0.56 Ni, 0.44 Cr, 0.18 MO. Austenitized at 845 “C (1555 “F). Grain size: 7. AC,, 795 “C (1460 “F); AC,, 745 “C (1370 “F). A: austenite, F: ferrite, P: pearlite, B: bainite, M: martensite
8640H: End-Quench Hardena bility Distance from quenched surface ‘&, in. mm 1 2 3 4 5 6 7 8 9 10 11 12
1.58 3.16 4.74 6.32 7.90 9.48 11.06 12.64 14.22 15.80 17.38 18.96
Hardness, HRC max mio 60 60 60 59 59 58 57 55 54 52 50 49
53 53 52 51 49 46 42 39 36 34 32 31
Distance from quenched su t-face 916 in. mm 13 14 15 16 18 20 22 24 26 28 30 32
20.54 22.12 23.70 25.28 28.44 31.60 34.76 37.92 41.08 44.24 47.40 50.56
Hardness. HRC ma\ mill 47 45 44 42 41 39 38 38 37 37 37 37
30 29 28 28 26 26 25 25 24 24 24 24
8640: Hardness Gradients. Nitrided to 20 to 30°0 dissociation.
(a) Nitrided for 7 h: (b) nitrided for 24 h; (c) nitrided for 48 h
466 / Heat Treaters
Guide
8840H: Hardenability (1600 “F). Austenitize:
Hardness purposes I distance,
mm
I1 3 .5 !O !5 10 \5 lo 15 i0
Curves. Heat-treating 845 “C (1555 “F)
limits for specification Hardness. HRC Minimum hlatimum 60 60 60 60 58 57 55 54 48 43 40 39 38 37 31
53 53 52 50 47 42 38 36 31 21 26 25 24 24 24
Hardness limits for specification wrposes I distance, /I6 in.
J IO 11 12 13 14 5 6 8 !O !2 !4 !6 !8 10 12
Hardness, HRC hlinimum Maximum 60 60 60 59 59 58 51 55 54 52 50 49 41 45 44 42 41 39 38 38 37 37 31 31
53 53 52 51 49 46 42 39 36 34 32 31 30 29 28 28 26 26 25 25 24 24 24 24
temperatures
recommended
by SAE. Normalize (for forged or rolled specimens
only): 870 “C
Alloy Steel / 467 8640:
Approximate
Critical
Points
8640H: Variation of Brine11 Hardness Measurements.
Critical
point
Tests
done on annealed plain carbon and low-alloy steels
Temperature T
AC, AC, Ar, Ar,
Source: Republic
Svrl
8640: Cooling Curves. Composition: (using interrupted Jominy method)
0.37 C. 0.87 Mn, 0.25 Si, 0.56 Ni. 0.44 Cr, 0.18 MO. Grain size: 7. Austenitized
at 845 “C (1555 GF)
Alloy Steel / 467
8642,8642H Chemical Composition. 8642. AISI and UNS: 0.40 to 0.45 C. 0.75 to I .OO Mn, 0.035 Pmas. 0.040 S ma. 0. IS too.30 Si. 0.30 to 0.70 Ni. 0.40 to 0.60 Cr. 0. I5 to 0.3 hlo. Uh’S HS6420 and SAE/AISI 8642H: 0.39 to 0.46 C, 0.70 to 1.05 Mn. 0. IS to 0.35 Si, 0.35 to 0.75 Ni. 0.35 to 0.65 Cr. 0.15 to0.25 Mo
temperature
Similar
Recommended
Steels (U.S. and/or Foreign).
J4O-l. 1412.5770.8642H.
8642. UNS G86420: SAE UNS H86.420: ASThl A304 SAE Jl268
Characteristics. Change in composition from 864OH is slight. Has essentiall) the same characteristics as described for 864OH. As-quenched surface hardness for 8642H. because the c&on content is slightly higher. is approximately 53 to 59 HRC. Hurdenabilib band is shifted upirard
slightlq for 8647H. methods
Forging.
by any one of the various
forging
Heat to 1230 ‘C (2250 “F) maximum. Do not forge after of forging stock drops brlo~r approximately 900 “C (I 650 W
Normalizing. Annealing.
Can be forged
Heat Treating
Practice
Heat to 870 “C t I600 “FL Cool in air
For a predominantly pearlitic structure, heat IO 830 “C ( IS35 “F). cool rapidl! to 775 “C t 1335 “F). then cool to 610 ‘C (I I85 “F). at a rate not to esceed I I “C t 20 “F) per h: or heat to 830 “C (I 525 “F), cool rapidI!, to 665 “C (I230 “Fj. and hold for 6 h. For B predominantly
468 / Heat Treaters
Guide
spheroidized structure, heat to 750 “C (1380 “F), cool rapidly to 725 “C (I 335 OF),then cool to 640 “C (118.5“F), at a rate not to exceed 6 “C (I 0 “F) per h; or heat to 750 “C (1380 “F), cool rapidly to 665 “C (1230 “F), and hold for 8 h Direct Hardening.
l l
Tempering. After quenching, reheat immediately to the tempering temperaturethat will provide the desiredcombination of mechanicalproperties
Austenitize at 855 “C (1570 “F), and quench in oil
Nitriding. Respondswell to ammoniagas nitriding as well asto ni~ding in any one of several proprietary mohen salt baths. The following is a commonly used cycle for ammonia gas nitriding: l
Seeprocessingdatafor 414OHfor other ni~ding cycles.Flamehardeningand ion nitriding arealternativeprocesses
Parts are austenitized, quenched, and temperedat 540 “C (1000 “F) or higher. (Temperingtemperaturemust always be higher than the nitriding temperature) Finish machine Nitride in ammoniagas for 10 to 12 h with an ammoniagas dissociation of 25 to 30%
Recommended
Processing
Sequence
Forge * Normalize l Anneal l Rough and semifinish machine l Austenitize and quench l Temper l Finish machine (grind if reauired) l Nitride (optionaiy 1 l
8642, 8642H: Hardness vs Tempering Temperature. sents an average based on a fully quenched structure
8642H: End-Quench Distance from quenched surface /16in. mm 1
2 3 4 5 6 7 8 9 10 11 12
1.58 3.16 4.74 6.32 7.90 9.48 11.06 12.64 14.22 15.80 17.38 18.96
Hardenability
Herdness. ERC max min
62 62 62 61 61 60 59 58 57 55 54 52
55 54 53 52 50 48 45 42 39 37 34 33
Distance from quenched surface l/16 in. mm
13 14 15 16 18 20 22 24 26 28 30 32
20.54 22.12 23.10 25.28 28.44 31.60 34.76 37.92 41.08 44.24 47.40 50.56
Hardness, HRC
39
26
Repre-
Alloy Steel / 469
8642H: Hardenability Curves. Heat-treating (1600 “F). Austenitize:
Hardness purposes I distance, nm 1.s \
iardness wrposes ; distance, 16 in.
845 “C (1555 “F)
limits for specification Hardness, Maximum
HRC illioimum
62 67 62 61 60 59 58 56 52 47 +I -II -lo 39 39
limits for specification Hardness, Maximum 67 62 62 61 61 60 59 58 57 55 5-l 52 so -19 -18 46 44 4’ -II 40 -IO 39 39 39
HRC biinimum
temperatures
recommended
by SAE. Normalize (for forged or rolled specimens
only): 870 “C
470 / Heat Treaters
Guide
8645,8645H Chemical Composition. 8655. AK1 and LNS: 0.43 to 0.48 C. 0.75 to I .OO Xln. 0.035 Pmax. O.O-lOS max. 0. I5 to0.30Si.0.40 too.70 Ni.0.40 to 0.60 Cr. 0. I5 IO 0.25 Ma IJNS H86450 and SAE/AISI 8645H: 0.Q to 0.49 C. 0.70 to 1.05 hln. 0.035 P max. 0.40 S mlt\. 0. IS to 0.30 Si. 0.35 to 0.75 Xi. 0.35 to 0.65 Cr. 0.15 10 0.25 Mo Similar
Steels (U.S. and/or Foreign).
86-15.l-33 G86-ljO: hlIL
SPEC MLL-S- 16973; SAE J-W. J-l 12.5770.8645H. A30-1: SAE Jl268
LX
H86450: AST\1
Hardening.
Characteristics.
A slightI> louer carbon version of 8650H. Asquenched hardness generally ranges from approximovly 5-l to 60 HRC. depending on the precise carbon content N ithin the allowable range. Considered a relaii\ely hiph-hardenahility steel. Used extensiveI! for a variety of machinery parts where hiph strength is required for riporous senice. including hiphly stressed shafts and springs. Can he forged. although just as is nue for other hipher carbon. high-hardenabilitj steels. forgings of complex shape should he cooled slowI> from the forging temperature 10 minimize the possibility of cracking
Forging. Heat IO 1230 “C (2250 ‘F) maximum. Do not forge after lemperature of forging stock drops helow approximateI! 925 “C (I695 “FL Cool slo\r Iy from rhe forging temperature
Recommended
Heat Treating
Annealing. For a predominantly pearlitic structure. heat to 830 “C ( I525 “F). cool slowly IO 7 IO “C ( I3 IO -‘FL then cool IO 650 “C ( I200 “F), at a rate not to exceed 8 “C (IS “F) per h: or heal to 830 “C (1525 “F), cool rapidI> to 650 ‘C (I200 “FL and hold for 8 h. For a predominantly spheroidized structure. heat to 750 “C (I380 “F). cool rapidly to 715 “C (1320 ‘Fj. then cool to 650 “C ( I200 “Fj. a1 a rate not to exceed 6 “C (IO ‘F) per h: or heat to 750 “C ( I380 “F). cool rapidl) to 650 “C (I 200 “F), and hold for IO h
Practice
hardening. processes
After quenching. pans should be tempered immediately. preferably when they are still warm to the touch. at 150 “C (300 “F) or hipher. For mosl purposes. higher tempering temperatures are used. Selection of tempering temperature is hased on the desired combination of mechanical properties
Recommended
Processing
l
Forge Normalize
l
Anneal
l
Rough and semifinish machine Austenitize and quench Temper Finish machine
l
l
Heat to 870 ‘C ( 1600 ‘FL Cool in air
at 845 ‘C ( IS55 “F), and quench in oil. Flame ion nitridinp. and carbonitiding are suitable
Tempering.
l
Normalizing.
Austenitize gas nitridinp.
l
Sequence
8645, 8645H: Hardness vs Tempering Temperature. Represents an average
8645H: End-Quench Hardenability Distance from quenched surface ‘/&in. mm 1
2 3 4 5 6 7 8 9 10 11 12
1.58 3.16 4.14 6.32 7.90 9.48 11.06 12.64 14.22 15.80 17.38 18.96
Hardness, EIRC max min
63 63 63 63 62 61 61 60 59 58 56 55
56 56 55 54 52 50 48 45 41 39 37 35
Distance from quenched surface ‘46 in. mm
13 14 15 16 18 20 22 24 26 28 30 32
20.54 22.12 23.70 25.28 28.44 31.60 34.76 37.92 41.08 44.24 41.40 50.56
Eardness. ARC
41
27
based
on a fully quenched
structure
Alloy Steel / 471
8545: Microstructures. (a) 2% nital. 825x. Hot rolled steel bar, 25 mm (1 in.) diam, austenitized at 815 “C (1500 “F) for 1 h and furnace cooled, resulting in a fully annealed structure. Dark areas lamellar pearlite. white areas ferrite. (b) 2?L nital. 750x. Same steel and bar size as (a). Austenitized at 815 “C (1500 “F) for 1 h, cooled to 675 “C (1245 “F), and held for 8 h (for spheroidizing). Dark areas, partly spheroidized pearlite, white areas ferrite. See (c). (c) 5% picric acid, 2 1Q ?& HNO,, in ethanol: 5000x. Same bar size as (a) and (b), same heat treatment as (b). Replica electron micrograph shows a structure that consists of partly spheroidized pearlite. (d) 2% nital, 1000x. Same bar size as (a), (b), and (c). Austenitized at 845 “C (1555 “F). water quenched, tempered at 260 “C (500 “F) for 1 h. Tempered martensite. See (e). (e) 29/o nital. 1000x. Same bar size as (a), (b), (c) and (d). Heat treatment same as (d). except tempered at 370 “C (700 “F). Tempered martensite. See (f). (f) 59’0picric acid, 2 1,/2?0HNO,, in ethanol: 10 000x. Same bar size and heat treatment as (e). Electron micrograph of platinum-carbon-shadowed two-stage carbon replica, showing carbide particles that precipitated from the martensite matrix. (g) 2% nital, 1000x. Same bar size as (f), austenitized at 845 “C (1555 “F) for 1 h. water quenched, tempered at 480 “C (895 “F) for 1 h. Compare with (d) and (e); increasing tempenng temperature has little effect on the appearance of the tempered martensite. (h) 5% picric acid, 2 1/2% HNO,, in ethanol; 10 000x. Same bar size and heat treatment as (g). Electron micrograph. made using a platinum-carbon-shadowed two-stage carbon replica, shows particles of carbide that have precipitated from the matrix of tempered martensite
472 / Heat Treaters
Guide
8645H: Hardenability (1600 “F). Austenitize:
Hardness purposes I distance, mm 1.5
Hardness purposes I dislance. %6 in.
IO
I1 12 13 14 15 16 18 !O !2 !4 !6 !8 i0 !2
Curves. H at-treating 845 “C (1555 “F)
limits for specification Hardness, Maximum
HRC Minimum
63 63 63 63 62 61 59 58 54 49 46 43 42 42 41
56 56 55 53 51
48 45 41 34 31 29 28 27 27 27
limits for specification Hardness. 3latimum
63 63 63 63 62 61 61 60 59 58 56 55 54 52 51 49 47 45 43 42 42 41 41 41
HRC \linimum
56 56 55 54 52 50 48 45 41 39 37 35 34 33 32 31 30 29 28 28 27 27 27 27
temperatures
recommended
by SAE. Normalize (for forged or rolled specimens
1
only): 870 “C
Alloy Steel / 473
86645,86645H Chemical
Composition.
86845. AISI: 0.43 IO 0.48 C. 0.75 to I .Oo
~ln.O.O3SPmax.0.~0Smax.0.20to0.3SSi.0.~0to0.70Ni.0.~0to0.60 Cr. 0. IS to 0.75 MO. 0.0005 B min. Uh?k 0.13 to 0.48 C. 0.75 to 1.00 \ln. 0.035 Pmax. O.MO S max.0.1. too.30 Si. O.-IO too.70 Ni. 0.10 toO.hOCr. O.lS to 0.25 MO. 0.0005 B min. LXS H&451 and SAE/AISI 86845H: 0.12 to 0.49 C. 0.70 to I.05 Sin. 0.15 to 0.35 Si. 0.35 to O.iS Si. 0.35 to O.hS Cr. 0. IS to 0.X MO. B (can be expected to be 0.0005 to 0.003 percent)
Similar
Steels (U.S. and/or Foreign).
ASTXl
ASl9: SAE J-IO-I. J-II?. ,430-t: SAE J I268
86BG.
5770. 86B45H.
LKS
LNS H&IS
G86JSl. I: ASTY
Characteristics.
LVith the exception of the boron addition. 86B-ISH is identical in composition to 8tiSH. Commercial applications for these ttvo steels are similar. 86BlSH is chosen \vhen more hardenabilitj is needed than can be provided b> 86-lSH. 86B-lSH is significantI> higher in hardenahility. As-quenched surface hardness is the same for the t\io steels. usually ranging from 51 to 60 HRC. Compares fa\orablj uith 86-lSH in forgeability and response to heat treatment
Forging.
Heat to I??0 ‘?I (Z’S0 ‘F) masmium. Do not forge after temperature of forging stock drops helow npprosmiatel> 9X “C ( I695 ‘FI
Recommended Normalizing.
Hardening. .\ustenitize at X-IS ‘C t ISSS ‘F). and quench in oil. Flame hardening. pas nitriding eon nitridinp. carhonitridinp, and fluidized bed nitriding are suitable processes Tempering.
.\fter quenching. parts should be tempered immediateI>. Selection of tcmperinp temperature depends on the desired mechanical properties
Recommended l l l l
Practice
l
Heat to 870 ‘C t I600 ‘FJ. Cool in air
l
86645: Isothermal
Heat Treating
Annealing. For a predominantI> pearlitic structure. heat to 830°C (IXS “F). cool rapidly to 73S ‘C t 1335 ‘FL then cool to 6-10 “C (I I85 “F). at a rate not to exceed I I ‘C (20 “F) per h: or heat to 830 ‘C ( IS25 “F). cool rapidly to 665 ‘C ( I230 “FL and hold for 7 h. For a predominantI> spheroidized structure. heat to 7SO ‘C t 1380 “F). cool rapidly to 72.5 “C ( I.335 ‘F). then cool to 640 ‘C (I I85 ‘F). at a rate not to exceed 6 “C i IO “F) per h: or heat to 750 ‘C i 1380 “FL cool rapidly to 665 “C (I230 “F). and hold for IO h
Transformation
l
Diagram. Composition:
0.45 C. 0.89 Mn, 0.59 Ni. 0.66 Cr, 0.12 MO, 0.0015 at 845 “C (1555 “F). Grain size: 6 to 7
Processing
Sequence
Forge Norninlize Xnneai Rough and semifinish machine Austenitize and quench Temper Finish machine
86B45H: End-Quench Hardenability
B. Austenitized Distance From quenched surface 1,SIbin. mm
Hardness. HRC max miu
Distance frum quenched surface !I16 in. mm
I.1 I-I IS I6 I8 20 22 2-t 26 28 30 32
20.51 ‘2.12
Eardness. ERC max min
59
19
23 70
59 58
48 46
3.X x-u 3 I.60
58 58 5X
4s 12 39
31.76 37.9’ 4 I .08 44.24 47 10 50.56
ST s7 57 57 5b 56
37 35 3-l 32 32 31
474 / Heat Treaters
Guide
86845H: Hardenability Curves. Heat-treating “C (1600 “F). Austenitize: 845 “C (1555 “F)
Hardness purposes I distance, nm
limits for specification Eardoess, Maximum
1.5
63 63 63 62 62 61 61 60 59 58 58 57 57 56 56
s
I1
13 I5 !O !5 50 15 lo
I5
io
iardness wrposes I distance. 4,j in.
0
1 2 3 4 5 6 8 10
!2 !4 !6 !8 IO
I2
temperatures
limits fo
56 56 55 54 53 52 51 51 49 45 40 36 33 32 31
r specification
Hardness. hlasimum
63 63 62 62 62 61 61 60 60 60 59 59 59 59 58 58 58 58 57 57 57 57 56 56
HRC Minimum
ARC Minimum
56 56 55 54 54 53 52 52 51 51 50 50 49 48 48 45 42 39 37 3.5 34 32 32 31
recommended
by SAE. Normalize (for forged or rolled specimens
only): 870
Alloy
86B45: Hardness vs Diameter. Composition: 0.43 to 0.48 C, 0.75 to 1 .OO Mn, 0.040 P max, 0.040 S max, 0.20 to 0.35 Si, 0.40 to 0.70 Ni. 0.40 to 0.60 Cr, 0.15 to 0.25 MO, 0.0005 B min. Approximate critical points: AC,, 720 “C (1330 “F). AC,, 770 “C (1420 “F); Ar,, 695 “C (1280 “F); Ar,, 650 “C (1200 “F). Recommended thermal treatment: forge at 1205 “C (2200 “F) maximum, anneal at 790 to 845 “C (1455 to 1555 “F) for a maximum hardness of 207 HB. normalize at 845 to 900 “C (1555 to 1650 “F) for an approximate hardness of 277 HB, quench from 830 to 855 “C (1525 to 1570 “F) in oil. Test specimens were normalized at 870 “C (1600 “F) in over-sized rounds, quenched from 845 “C (1555 “F) in oil, tempered at 540 “C (1000 “F), and tested in 12.8 mm (0.505 in.) rounds. Tests from bars 38 mm (1.50 in.) and over are taken at half radius position. Source: Republic Steel
Steel
/ 475
86845: Hardness vs Diameter. Composition: 0.43 to 0.48 C, 0.75 to 1 .OO Mn. 0.040 P max, 0.040 S max. 0.20 to 0.35 Si, 0.40 to 0.70 Ni, 0.40 to 0.60 Cr. 0.15 to 0.25 MO, 0.0005 6 min. Approximate critical points: AC,, 720 “C (1330 “F). AC,, 770 “C (1420 “F); Ar,, 695 “C (1280 “F); Ar,, 650 “C (1200 “F). Recommended thermal treatment: forge at 1205 “C (2200 “F) maximum, anneal at 790 to 845 “C (1455 to 1555 “F) for a maximum hardness of 207 HB, normalize at 845 to 900 “C (1555 to 1650 “F) for an approximate hardness of 277 HB, quench from 830 to 855 “C (1525 to 1570 “F) in oil. Test specimens were normalized at 870 “C (1600 “F) in over-sized rounds, quenched from 845 “C (1555 “F) in oil, tempered at 650 “C (1200 “F), and tested in 12.8 mm (0.505 in.) rounds. Tests from specimens 38 mm (1 l/z in.) and over were taken at half radius position. Source: Republic Steel
Alloy Steel / 475
8650,865OH Chemical
Composition. 8650. AISI: 0.48 to 0.53 c, 1~75 to 1.00 Mn.0.~0Pn~lut.0.~0Sn~ax.0.30to0.35Si.0.~0to0.70Ni.0.10to0.60 Cr. 0.15 to 0.35 hlo. UNS: 0.48 to 0.53 C. 0.75 to 1.00 hln. 0.035 P max. 0.0-10 S max. 0.15 to 0.30 Si. O.-t0 to 0.70 Ni. 0.40 to 0.60 Cr. 0. IS to 0.X Mo. UNS H86500 and SAE/AISI 86508: 0.47 to 0.5-I C. 0.70 to I .OS hln. 0.15 to 0.35 Si. 0.35 to 0.75 Ni, 0.35 to 0.65 Cr. 0. IS to 0.35 hlo Similar
Steels (U.S. and/or Foreign). 8650. UNS G86500: ASTM A322. A5 19: SAE J-KM. J-l I?. J770.86508. UNS H86500: ASThl A304: SAE J I368
spheroidired structure. heat to 750 “C t 1380 “F), cool rapidly to 715 “C I 1320 “F). then cool to 650 ‘C t IX) “F). at a rate not to exceed 6 “C t IO “F) per h; or heat to 750 “C ( I380 “F). cool rapidly to 650 “C (I X0 “F). and hold for IO h
Hardening. Austenitize at 845 “C I 1555 “F). and quench in oil. Flame hardening. gas nitriding. ion nitriding. and carbonitriding are suitable processes Tempering.
After quenching. parts should be tempered immediately (preferahly ashen they are still ~iarrn to the touch) at IS0 “C (300 “F) or higher. For most purposes. higher tempering temperatures are used. Selection of temperins temperature is based on the desired combination of mechanical properties
Characteristics. Borderline between I$ hat is usually considered a medium-carbon grade and a high-carbon grade alloy steel. When the carbon is on the lower side of the allowable range. oil-quenched hardness of approxtmately 56 HRC can he expected. When the carbon content is near 0.5-L an as-quenched hardness of approximately 61 HRC can be expected. Hardenability is relatively high. Used extenskely for a variety of machiner) parts where high strength is required for rigorous service. notahly for highly stressed shafts and springs. Can be forged. although as is true for other higher carbon. high-hatdenability steels. forgings of complex shape should he cooled slo~+ly from the forging temperature to minimize the possibilit) of cracking
l
Forging.
l
Recommended l l l l l
Heat to 1130 “C (3%) “F) maximum. Do not forge after temperature of forging stock drops below approximately 925 “C t I695 “F J Cool slowly from the forging temperature
Recommended Normalizing. Annealing.
Heat Treating
Processing
Sequence
Forge Nomralire Anneal Rough and semifinish machine Austenitire and quench Temper Finish machine
8850:
Approximate
Critical
Points
Practice
Heat to 870 “C (I 600 “FL Cool in air
For a predominantly prarlitic structure. heat to 830 “C t IS25 OF), cool slowly to 7 IO “C ( I3 IO “F). then cool to 650 “C t I ZOO “F). at a rate not to exceed 8 “C t IS “F) per h: or heat to 830 “C ( IS35 OF). cool rapidly to 650 “C (IZOO “F), and hold for 8 h. For a predomjnantly
Temperature Critical As, Acq Ari Ar.
point
T
OF
730 770 700 655
1350 I420 I295 1210
476 / Heat Treaters
Guide
8650: Continuous Cooling Transformation Austenitized
Diagram. Composition:
0.48 C. 0.75 Mn, 0.020 P, 0.010 S. 0.34 Si. 0.60 Ni, 0.58 Cr, 0.20 MO.
at 850 “C (1560 “F)
8650: Hardness vs Tempering Temperature. Composition: 0.48 to 0.53 0.75 to 1.00 0.20 to 0.35 0.40 to 0.70 0.40 to 0.60 Cr, 0.15 to 0.25 MO. Forged at 1175 “C (2150 “F) maximum and annealed by furnace cooling from 815 to 925 “C (1500 to 1695 “F). Maximum annealed hardness, 212 HB. Normalized at 870 “C (1600 “F) with a hardness of 355 HB for test size. Quenched in oil at 845 “C (1555 “F) and tempered for 2 h. Source: Republic Steel
Alloy
8650H: Hardenability (1600 “F). Austenitize:
Hardness purposes I distance,
mm I.:’
Hardness purposes I distance. ‘!,,6 in.
Curves. Heat-treating 845 “C (1555 “F)
limits for specification Hardness,
Maximum
HRC Minimum 59 SY 98 56 sj 53 50 16 38 3-f 32 31 30 29 29
6.5 65 65 65 64 63 62 61 59 57 51 52 19 -17 46
limits for specification Hardness.
hlasimum h5 cl.5 65 b-l M h3 63 h2 61 60 60 59 58 58 47 Sb 5s 53 52 SO 19 37 .lb 45
HRC hlinimum 59 58 51 57 5h 51 53 SO -1-l 4-l -II 39 37 36 35 3-1 33 32 ?I 31 30 30 2’) 29
temperatures
recommended
by SAE. Normalize (for forged or rolled specimens
Steel / 477
only): 870 “C
478 / Heat Treaters
Guide
885OH: End-Quench Hardenability Distance from quenched surface !.‘16in. mm I 2 3 4 5 6 7 8 9 10 II
I..58 3 16 17-l 6.3’ 7.90 9.48 II 06 1264 11.12 IS 80 17.38
Hardness, HRC max min 65 65 6S 64 64 b3 63 62 61 60 60
99 58 57 57 56 S-l 53 so 47 4-I II
8650: Microstructure. Distance from quenched surface !/IS in. mm 13 I4 IS lb I8 20 ‘2 7-l ‘6 28
20.5-l x.1?. 23.70 25 28 ‘8 4-l 31.60 34.76 37.92 -I I .oa 44.2-l
Hardness, HRC max min 58 S8 57 56 5s 5.3 51 so 49 -17
37 36 3s 3-I 33 32 31 31 30 30
2% nital, 500x. Hot rolled steel bar, 7.936 mm (0.31 in.) hexagonal, austenitized at 750 “C (1380 “F) 3 h, furnace cooled to 665 “C (1230 “F) and held 6 h, air cooled, cold drawn, reheated to 665 “C (1230 “F) for 10 h, furnace cooled. Spheroidized cementite and lamellar peariite in ferrite
478 / Heat Treaters
Guide
8655,8655H Chemical Composition. 8655. AISI and UN% 0.5 I to 0.59 C. 0.75 to I .OO hln.0.035 Pmax. 0.03OS max. 0.15 too.30 Si. 0.10 too.70 Ni.O.-lO IO0.60Cr. 0.15to 0.35 hlo. UNSHS6550and SAE/AIS18655H:O.SOto 0.60C.0.70to 1.05 hln.0.15 to035 Si.O.35 too.75 Ni.O.lS 100.25 MO Similar
Steels (U.S. and/or
ASTM A322 AW;SAEJI268
A33l:
Foreign).
SAE J-IO-L J-II’.
8655.
5770. %%H.
G86sso: UNS UNS H86Y5050:A!ST&l
Characteristics.
A high-carbon sted. A spnnp sled. although it is used IO fabricate a variety of machinery parts not related to sprinps. .As-quenched hardness after quenching tn oil usually ranges from 57 to 62 HRC. depending on exact carbon content. A high-hardenability steel. although the hand is generally wide. Is forgeable. but not recommended for iteldinp because of its high carbon content rend high hardenability
Forging. Heat to 1200 “C (2190 “F) masimum. Do not forge after temperature of forging stock drops below approximately 925 “C ( 1695 ‘F). Forgings of this grade should he cooled slo\vly from the forging operntion. especially if they have complex shapes. Bury them in an insulating compound or place them in a furnace
Recommended Normalizing.
Heat Treating
Practice
Heat to 870 “C ( I600 “F). Cool in air
Annealing.
For a predominantly spheroidized structure. which is preferred for machining and heat treakng 86SSH. heat to 750 “C (I380 “F), cool rnpidly to 700 “C ( I290 “F). then cool to 655 “C (I 2 IO “F). at a rate not to exceed 6 “C t IO “F) per h: or heat IO 750 “C ( I380 “F), cool rapidly to 650 “C ( I200 “FJ. and hold for IO h
Direct Hardening. Flame hardening. able processes
.Austenitizs ttt 830 “C ( lS2S “F), and quench in oil. gas nitridinp. ion nitriding. and carbonitriding are suit-
Tempering.
After quenching to nelu ambient temperature. temper immediately at I SO “C (300 “F) or higher. The selection of tempering temperature depends on the required hardness or mechanical properties. 86SSH is sensitke to quench cracking. and 1001 steel practice should be obsemed in tempering. Parts should not be allowed to become too cold after quenching before they are placed in the tempering furnace. A uniform temperature of approximately 38 to SO “C t 100 to I20 “F) is preferred
Austempering.
\\‘hen used for applications such as heavy-duty springs. 865SH is sustempered in a procedure such as the one that follows:
Alloy
Auslenitize at 830 “C (1525 “F) Quench in an agitated molten salt hnth held at 315 “C (655 “F) . Hold at 345 “C (655 “F) for I h l Air cool to room temperature l \Vash in hot natrr
Recommended
l l
l l l l
No tempering is required. Hardness for pxts should range from approximarsl) 47 10 57 HRC
l l l
8855, 8655H:
Distance from quenched surface 916 in. mm 1 2 3 4 5 6 7 8 9 10
1.58 3.16 4.14 6.32 7.90 9.48 11.06 12.64 14.22 15.80
11 12
17.38 18.96
Hardenability
Hardness, HRC max min
Distance from quenched surface l/l6 in. mm
Hardness, HRC min max
65
60 59 59 58 57 56 55 54 52 49
13 14 15 16 18 20 22 24 26 28
20.54 22.12 23.70 25.28 28.44 31.60 34.76 37.92 41.08 44.24
64 63 63 62 61 60 59 58 57 56
41 40 39 38 31 35 34 34 33 33
65 64
46 43
30 32
47.40 50.56
55 53
32 32
I479
Sequence
Forge Normalize Anneal Rough md semifinish machine Austenitize and quench (or nuskmper) Temper (or austrmper) Finish machine CUSUAI~ grinding)
sents an average
8655H: End-Quench
Processing
Steel
Hardness based
vs Tempering
Temperature.
on a fully quenched
structure
Repre-
480 / Heat Treaters
Guide
8655H: Hardenability
Curves. Heat-treating 845 “C (1555 “F)
(1600 “F). Austenitize:
Hardness purposes J distance. mm
limits for specification Hardness, hladmum
HRC Minimum 60 60 59 57 56 55 53 51 42 39 3h 34 34 33 32
65 h5 6-l 62 60 58 56 5-l
Hardness purposes J distance. 1/1b io-
0 1 2 3 4 5 6 8 :0 !2 !4 :6 :s 80 12
limits for specification Hardness, hlatimum
65 65 64 64 63 63 62 61 60 59 58 57 56 55 53
HRC hfinimum 60 59 59 58 57 56 55 54 52 49 46 43 41 40 39 38 31 35 34 34 33 33 32 32
temperatures
recommended
by SAE. Normalize (for forged or rolled specimens
only): 870 “C
Alloy Steel / 481
8660,866OH Chemical
Composition. 8660. AISI: 0.55 to 0.65 C. 0.75 to 1.00 hln.0.0-10Pmax,0.0~OSmax.O.2Oto0.3SSi.O.10to0.70Ni.0.-10to0.60 Cr. 0. IS to 0.X MO. UNS: 0.55 to 0.65 C. 0.75 to I.00 hln. 0.035 P max. 0 040 S max. 0.15 to 0.30 Si. O.JO to 0.70 Ni. O.-IO to 0.60 Cr. 0. IS to 0.25 hlo. UNS HS6600 and SAE/AISI 86608: 0.55 LO0.65 C. 0.70 to I .OS Mn. 0. IS to 0.35 Si. 0.35 to 0.75 Ni. 0.35 to 0.65 Cr. 0. IS to 0.35 MO Similar
Steels (U.S. and/or Foreign).
ASThl A27-L A33Z. A333. ASl9: H86600: ASThl A3O-l: SAE J I?68
SAE J-W.
UNS ~86600; 8660. J-ll2.1770. 86608. GINS
Characteristics. A spring stssl used for a uide \ariety of machinsq parts where high strength and high h,ardcnabilit) are important. Also used for a variet) of metal working tools including cold \\orl; dies. When the carbon is on the IOU side of the allo~~ablz range. the as-quenched hardness for an oil-quenched part ma) hz no higher than about 59 HRC. but when the carbon approaches the upper limit. the as-quenched hardnesb can he as high as 65 HRC. The hardenahilit) hand is relativeI! wide. hut the hardenahility can he \eq high. actually approaching that of an au-hardening Steel Forging. Heat to 1200 ‘C rZl9O “FI ma\irnum. Do not forge atier temperature of forging stock drops belo\{ approsimatelj 925 YI ( 169.i “F). Forgings of this grade should be cooled slou I! from the forging operation. especially if they have complex ,hapcs. Buq them in an insulatmg compound or place them in a furnace
Tempering.
.After quenching to near ambient temperature, temper immediateI> al I SO “C 1300 “F) or higher. The selection oftempering temperature depends on the required hardness or mechanical properties. 866OH is sensiti\c to quench cracking. and tool steel practice should be observed in tempertng. Parts should not be allowed to become too cold after quenching before they are placed in the tempering furnace. A uniform temperature of approximateI> 38 to SO ‘C t IO0 to I20 “F) is preferred
Austempering.
H’hen used for applications such as heavy-duty sprmgs. 86SSH is austempered in a procedure such as the one that follows: l l l l l
No trmpenng 47 to 52 HRC
l l l l
l
Normalizing.
Heat Treating
Practice
15
requued. Hardness for parts should range from approximately
Recommended
l
Recommended
Austenitize at 830 “C t IS25 “FI Quench in an agitated molten salt bath held at 3-lS “C (655 “F) Hold at 3-0 “C 1655 “F) for I h Air cool lo room temperature L\‘abh in hot \bater
l
Processing
Sequence
Forge Normalize .Anneal Rough and semifinibh ~nnchins jrulrtsnitize and quench (or austsmper) Temper Ior austempcr) Finish machine ~usuallg grinding)
Heat to 870 ‘C t I600 “F). Cool in air
Annealing.
For a przdormnantly spheroidized structure. uhich is usually preferred for machining as well as heat treating. heat to 7S0 “C t 1380 “FJ. cool rapidI> to 700 “C ( I?90 ‘F). then cool to 6SS “C ( I2 IO “Ft. at a rate not to esceed 6 “C ( IO “F) per h: or heat to 750 ‘C I I380 “F). cool rapidly to 650 “C I I200 “F). and hold for IO h
8660:
Approximate
Critical
Points Temperature
Critical point
Direct Hardening. Flame hardening.
Austenitire at 830 “C I IS2 “FL and quench in oil. gas nitriding. and ion nitridinp. are altematite procebses
8660: Isothermal
Transformation
C. 0.89 Mn, 0.53 Ni. 0.64 (1555 “F). Gram size: 8
Cr, 0.22
Diagram.
Composition: 0.59 MO. Austenitized at 845 “C
482 / Heat Treaters
Guide
8660: Hardness vs Tempering Temperature. Composition: 0.55 to 0.65 C, 0.75 to 1.00 Mn, 0.20 to 0.35 Si, 0.40 to 0.70 Ni, 0.40 to 0.60 Cr, 0.15 to 0.25 MO. Forge at 1175 “C (2150 “F), anneal from 815 to 925 “C (1500 to 1695 “F) for a maximum hardness of 229 HB. Hardness after normalizing in test size, 321 HB. Normalized at 870 “C (1600 “F), quenched in oil from 845 “C (1555 “F), tempered 2 h. Source: Republic Steel
8660: End-Quench
Hardenability. Composition: 0.59 C, 0.89 Mn, 0.53 Ni, 0.64 Cr, 0.22 MO. Austenitized at 845 “C (1555 “F). Grain size 8
8660H: End-Quench Hardenability Distance from quenched surface I.,16in. mm I 3 ;
Hardness. HRC min max
158
60 60 60
1.71 3.16 6 32 7.90 9.48
.:: .:’
II.06 12.6-l 11.22 IS.80 I7 38 I896
:” .:
Distance from quenched surface
“16h. I? I-l
mm
Hardness, HRC max min
X~..i-l 22.12 73 70
:
45 4-l -I!
60 60 59
3.28 28.U 31.641
6i 6-l 6-I
42 40 39
58 57
34.76 37.92
63 62
38 37
5s 53 50 47
1 I .08 1-1.2-t 47.40 50.56
62 61 60 60
36 36 36 3s
Alloy Steel / 483
8860H: Hardenability Curves. Heat-treating (1600 “F). Austenitize:
iardness wrposes distance, om
845 “C (1555 “F)
limits for specification Hardness, HRC Maximum hliuimum
.5
1 3 5 .O :5 ‘0 ‘5 0 .5 10
iardness wrposes distance, $6 in.
.
. 65 64 62 61 60
limits for specification Hardness, HRC Maximum hlinimum
.
0
1 2 3 4 5 6 8 0 2 4 6 8 0 2
60 60 60 60 59 58 56 53 46 42 39 38 37 36 35
. 65 64 64 63 62 62 61 60 60
60 60 60 60 60 59 58 57 55 53 50 41 45 44 43 42 40 39 38 37 36 36 35 35
temperatures
recommended
by SAE. Normalize (for forged or rolled specimens
only): 870 “C
1
484 / Heat Treaters Guide
8720,8720H,
8720RH
Chemical Composition. 8720. AISI and UNS: 0.18 to 0.23 C, 0.70 to0.90Mn,0.035 Pmax,0.040Smax,0.15 to0.30Si,0.40to0.70Ni,0.40 to 0.60 Cr. 0.20 to 0.30 MO. UNS II87200 and SAE/AISI 8720H: 0.17 to 0.23 C, 0.60 to 0.95 Mn, 0.15 to 0.35 Si, 0.35 to 0.75 Ni, 0.35 to 0.65 Cr, 0.20to0.30Mo.8720RH:0.18to0.23C,0.70to0.90Mn,0.15to0.35Si, 0.40 to 0.70 Ni, 0.40 to 0.60 Cr. 0.20 to 0.30 MO Similar Steels (U.S. and/or Foreign). 8720.
UNS G87200; ASTM A322; SAE J404,5770; (Ger.) DIN 1.6543; (U.K.) B.S. 805 A 20. 8720I-I. UNS H87200; ASTM A304, A914; SAE J1268, J 1868; (Ger.) DIN 1.6543: (U.K.) B.S. 805 A 20
Characteristics.
With the exception of a minor increase in the molybdenum content (0.20 to 0.30% as opposed to 0.15 to 0.25%), the composition of 8720H is identical with that of 8620H, and the characteristics are nearly identical. The only difference is that the hardenability of 87208 is slightly higher. Used for carburizing and carbonitriding where just a bit more hardenability is needed than can be provided by 82608. Has excellent forgeability and is readily weldable, although alloy steel practice should be used in welding to minimize susceptibility to weld cracking. Machinability is fairly good
Forging. Heat to 1245 “C (2275 OF) maximum. Do not forge after
(1220 OF), and holding for 4 h; or heat to 790 “C (1450 “F), cool rapidly to 660 “C (1220 “F), and hold for 8 h
Tempering. Temper all carburized or carbonitrided parts at 150 “C (300 “F), and virtually no loss of case hardness results. If some decrease in hardness can be tolerated, toughness can be increased by tempering at somewhat higher temperatures, up to 260 “C (500 “F)
Case Hardening. See recommended carburizing and carbonitriding procedures described for 86208. Ion nitriding and martempering are alternative processes. Quenchants include polymers Recommended l l l l l
l l
Processing
Sequence
Forge Normalize Anneal (if required) Rough machine Semifinish machine allowing only grinding stock, no more than 10% of the case depth per side for carburized parts. In most instances, carbonitrided parts are completely finished in this step Carburize or carbonitride and quench Temper
temperature of forging stock drops below approximately 900 “C (1650 OF)
Recommended Heat Treating Practice Normalizing. Heat to 925 “C (1695 OF). Cool in air Annealing. Structures having best machinability are developed by normalizing; or by heating to 885 “C (1625 “F), cooling rapidly to 660 “C
8720, 8720H: Hardness vs Tempering Temperature. sents an average based on a fully quenched structure
8720H: End-Quench
Repre-
Hardenability
~
I 2 3 4 ; 7 8 9 IO II 12
I.58 3.16 4.7-l 6.32 7.90 9.1x I I ah 12.6-I 14.22 IS.80 17.38 IX.96
-18 -17 4s 12 28 35 33 !I 30 29 2x 27
-II 38 3s 30 ‘6 2-l 2’ 21 20
13 II I5 I6 18 20 22 21 26 2!3 30 32
10.5-l 22. I2 23.70 25.28 25-L-l 31.60 34.76 37.92 -I I .08 u.2-l 17.40 SO.56
26 26 3 ‘5 2-l 21 73 23 23 23 1’ 22
8720: Tempering Temperature vs Case Hardness. Carburized to a depth of 1.27 mm (0.050 in.). Rock bit journals 13 mm (0.50 in.) to 44.5 mm (1.75 in.) in cross section were carburized at 925 “C (1695 “F), air cooled from 845 “C (1555 “F), heated to 870 “C (1600 “F), oil quenched, tempered at 650 “C (1200 “F), reheated to 775 “C (1425 “F), oil quenched. and tempered at indicated temperatures
Alloy Steel / 485 8720H: Hardenability Curves. Heat-treating temperatures (1700 “F). Austenitize:
925 “C (1700 “F)
Hardness limits for specification purposes J distance. mm
Aardness. Maximum
4x -I7 45 II 37 33 31 29 ‘7 25 2-l 23 23 23 22
HRC hlinimum
-II 39 35 29 25 22 21
Hardness limits for specification purposes J distance, 1.‘16 in.
I ? 3 -I s 6 7 8 9 IO II IZ I3 IJ IS
I6 18 ‘0 ‘2 21 26 28 3CJ 32
Hardness, hlavimum
HRC hlinimum
recommended
by SAE. Normalize (for forged or rolled specimens
only): 925 “C
488 / Heat Treaters
Guide
8720RH: Hardenability “C (1700 “F). Austenitize:
Hardness purposes J distance, 1, 4i”. I 7 ; -I 5
6 7 8 9 I0 II I:! I3 I-l IS I6 IX
20 22
Hardness. hlaximum
HRC hlinimum
47 -2.5 13 .I0 36 33
-I2 39 37 32 28 26 2-l 23 72
31
29 28 27 26 2s 2s 2-l 2-l 23 23 22 22
2-l
21
20
J distance, mm
925 “C (1700 “F)
limits for specification
26 2x 30 32
Hardness purposes
Curves. Heat-treating
21
20
limits for specification Hardness, Maximum
HRC Minimum
temperatures
recommended
by SAE. Normalize
(for forged or rolled specimens
only): 925
Alloy Steel / 487
8720: Microstructures. Note: All microstructures for 8720 were hot rolled specimens treated uniformly before described heat treatments: gas carburized for 9 h at 925 “C (1695 “F) at 1.35% carbon potential and diffused for 2 h at the same temperature at 0.90% carbon potential. The center of the field in the micrographs ranges from 0.127 to 0.254 mm (0.005 to 0.010 in.) beneath the carburized surface. (a) 5% nital, 1000x. Slowly cooled in the furnace from the carburizing temperature. Light carbide network in a matrix of lamellar pearfite. (b) 5% nital, 1000x. Austenitized at 0.90% carbon potential for 1 h at 815 “C (1500 “F), oil quenched, tempered for 1 h at 190 “C (375 “F). Relatively lowcarbon tempered martensite. (c) 5% nital, 1000x. Same austenitizing and tempering treatments as (b). Globular carbide, retained austenite in tempered martensite of highercarbon content than (b). (d)5?” nital. 1000x. Austenitized at 0.65% carbon potential for 1 h at 815 “C (1500 “F), oil quenched. tempered for 1 h at 190 “C (375 “F). Retained austenite (white constituent) in a matrix of tempered martensite. (e) 5% nital, 1000x. Austenitized at 1.35% carbon potential for 1 h at 815 “C (1500 “F), oil quenched, tempered 1 h at 190 “C (375 “F). Carbide (light network, globular particles) in a matrix of tempered martensite. retained austenite not visible. (f) 5% nital, 1000x. Austenitized at 0.90% carbon potential for 1 h at 815 “C (1500 “F), quenched in oil, tempered for 1 h at 260 “C (500 “F). Small amount of retained austenite (white areas) visible in a matrix of over-tempered martensite. (g) 5% nital, 1000x. Austenitized at 0.90% carbon potential for 1 h at 815 “C (1500 “F), quenched in oil, tempered for 1 hat 120 “C (250 “F). Tempered martensite. showing effects of undertempering. (h) 5% nital, 1000x. Austenitized at 0.90% carbon potential for 1 h at 815 “C (1500 “F), rapidly air cooled, tempered for 1 h at 190 “C (375 “F). Fine pearlite (dark constituent) in a matrix of bainite. (j) 5% nital, 1000x. Same as (h), except oil quenched. Surface was improperly ground, being heated above the critical temperature and then rapidly cooled. Retained austenite (white) and untempered martensite result
L
(b)
Alloy Steel / 487
8740,874OH Chemical
Composition.
to l.OOMn.0.035
Pmax.O.WOS
8740. AISI and UNS: 0.38 to 0.43 C. 0.7s max.0.15 ~o0.30Si.0.40to0.70Ni.0.40
to0.60 Cr. 0.30to0.30 Mo. UNSH87JOO and SAE/AISI874OH:0.3710 0.14 C. 0.70 to I.05 hln. 0.15 to 0.35 Si. 0.3.5 to 0.75 Ni. 0.35 to O.hS Cr. 0.30 10 0.30 MO
Similar Steels (U.S. and/or Foreign). 8740. UNS G87400; AhlS 6332. 6313. 633. 6327. 6358: ASThl A313. A331: ML SPEC MIL-S6019; SAE J-W. J-II?. 5770: tGsr., DIN 1.6546: (I~al.) UNI 10 NiCrhlo 2 KB;(U.K.b B S.T!,pr7.874OH. 1lNS HX7100: ASTMA3M:SAEJl168: (Grr.) DIN 1.6546: (Ital.1 LlNl 10 NiCrhlo 2 KB: (U.K.) B.S. Type 7
488 / Heat Treaters
Guide
NearI) identical in composition to 8640H. The onl) Characteristics. difference is a sli_rhtl> higher molybdenum range. 0.20 to 0.303 for 8710H as opposed to 0. IS IO 0.2‘-5 for 8640H. This minor difference does not change the as-quenched hardness. but does offer a light increase In bardrnahilib. If desired. can he nitrided to achis\r surfaces Ihal help 10 resist abrasion and further Increase fatigue strenpth. An ns-quenched surface hardness of approsimatel) 52 IO S7 HRC can he expected. depending on the precise carbon content. Can he forged h! an> one of the wious forging method\
Nitriding. Responds nell to ammoniagas nitridins as well as II) nitriding in any one of several proprietary molten sah baths. The following is a cycle used with ammonia &as mtriding: l
l
l
Forging. wmperature
Heat 10 1230 ‘C t22SO “F) maximum. Do not forge after of iorging stock drops hslou appronnnatel~ 900 ‘xY ( l6SO “F)
Parts are austenitirsd. quenched, and tempered al 540 “C (I000 “F) or higher. (Tempering temperature must aLays he higher [ban the &riding temperarure) Finish machine (must he done hefore nitriding. because of resulting thin case 1 Nilrids In ammonia gas for IO to I? h I\ ith an ammonia gas dissociation of 2s to 305
See procrssmg data for 1 I-LOH for other nilriding
Recommended Normalizing.
Heat Treating
Practice
Tempering.
.Aftcr quenching. reheat immediately to the tempering temperature that M ill provide the desired combination of mecharucal properties
Heal to 870 ‘C ( I600 “FJ. Cool in air.
In aerospace pracke.
parts are normalized
at 900 “C ( 1650 “F)
Annealing.
For a predominanU> penrlitic wuuc‘rure. heat to 830 ‘C ( IS3 “FL cool rapidly to 73 ‘C ( I335 “FL then cool to 640 ‘C ( I I85 “‘F), a~ a ra[e not IO exceed I I “C (10 “F) per h: or heat to X30 “C ( IS3 ‘F). ~‘001 rapidly to 665 “C ( I230 “F). and hold for 6 h. For a pr?dominantl> sphrroidized wucture. heat to 750 “C I 1380 “F). cool rapid11 to 73 “C I I335 “FL then cool to 640 “C ( I I85 “FL at a rate nor to exceed 6 “C ( IO “FB per h; or heat to 750 YI ( 13X0 ‘FJ. cool rapid11 to 665 “C ( 1230 “FJ. and hold for 8 h In aerospace practice. parts are annealed at 845 “C I ISSS “F). cooled IO helo\\ S-IO “C ( 1000 “F) at a rate not IO exceed 95 “‘C 1200 “F) per h
Other Processes. Ion nitriding. austempering and martempering are altemath e processes. In aerospace practice. parts WC austenitized at 8-15 “C I IS55 “F). then quenched in oil or polymers
Recommended l l l l l l l
Hardening.
Direct
.Austenirizs
at XSS :‘C (’ IS70 “FL and quench in oil
l
Processing
Specimens
quenched
Hardness
in.
mm
Surface
on Hardness Hardness, HB Size round
in oil
Size round
Sequence
Forge Normalize .Annsal Rouph and semifinish machine Austsnitize and quench Temper Finish machine (grind if required) Nitride (optional)
8740: Effect of Heat Treating 8740: As-Quenched
cycles
Hardness, HRC ‘A_ radius
Condition
‘iin. (13mm)
1 in. (2.5 mm)
2ill. (51 mm)
4in. (102 mm)
201 169 352 302 285
261 331 ‘71 25.5
755 277 X8 ‘29
Center r\nnrakdiar Nomlalircd~ b) 011 qusnchrdli, Oil quenchrdld,
311
011qucnshedlr)
3s
‘69
352
(al Haled m IWO “F 11115‘CL furnace cwlcd 20 ‘IF f I I “C) to I IO0 “F (595 “C). cooled intir. lb) Healed to IhOO“Ft870 “CL cooled in air. (cl Fmm IS15 “F(830”C). lemprrzd II 1001)“F (5-10 ‘Cl. Id) From I525 “F (8.10 “CJ. tempered at I IO0 “F (59.5 ‘CL 151From IS3 “Ft830’C~. temperedat INJ”FI~SO”C). Source: RepublicSteel
8740, 8740H: sents an average
Hardness vs Tempering Temperature. Reprebased
on a fully quenched
structure
Alloy Steel / 489
3740H: Hardenability Curves. Heat-treating :1600 “F). Austenitize:
lardness lurposes distance, ,m .5
1 3 5 0 5 0 5 0 5 0
iardness wrposes distance, ‘16in.
845 “C (1555 “F)
limits for specification Hardness, HRC Minimum Maximum
60 60 60 60 59 58 56 54 50 45 43 41 40 39 38
limits for specification Hardness, HRC Maximum Minimum
60 60 60
0 1 2 3 4 5 6 8 0 2 4 6 8 0 2
53 52 51 49 46 43 39 36 31 29 28 27 27 26 26
60 59 58 57 56 55 53 52 50 49 48 46 45 43 42 41 40 39 39 38 38
53 53 52 51 49 46 43 40 31 35 34 32 31 31 30 29 28 28 21 21 27 27 26 26
temperatures
recommended
by SAE. Normalize (for forged or rolled specimens
only): 870 “C
1
490 / Heat Treaters Guide 8740: Suggested Tempering Temperatures (Aerospace Practice)* 620460 MPa (90-125 bi)
860-1035 hlPa (125-150 ksi)
690 “C I I275 “FJ
635 ‘T 11175°F)
Tensile Strength Range 1175-1210 MPa 1035-1175 hlPa (170480 ksi) (150-17Oksi)
1240-1380 hlPa (180-200 ksi)
1380-1520 MPa (200-220 ksi)
455 “C (850°F)
385 “C (735 “FJ
925 “C (975 “F)
580 “C (1075 “FJ
* Quench m oil or poljmrr. Source: AhlS 27S9/1
8740:
Suggested Tempering Temperatures Based on As-Quenched Hardness (Aerospace Practice)
Tensile strength range
RC 47-19
RC 50-52
RC 53-55
RC -56-58
620 - IO35 MPa (90-1.50 ksi) 965-l 105 MPa (140-160 ksl) 1035-l 175 MPa (ISO-17Oksij I I OS-I230 MPa (160-180 ksl) 1175.1310MPa (170-190 ksl) 1210-1380 MPa (180-200 ksi) 1380-1515 MPa (200-220 kji)
595 “C (IIOO”FI 525 “C 197.5“FI 470 “C 187S’F)
620 ‘T (1150°F) 550 “C (IO2S “F, 510°C (950 “F) 480 “C (900 “F) 4lO”C (775 ‘F) 385 “C (725 OF)
(650 ‘T) I 1200°F) 595 “C (IIOO”FI 550 “C (IO15 “R 52s “C (975 “F) 470 “C (R75 “F) -130 @C (825 OF) 110 T (775 “F)
675 “C ( 1250 “F) 635 “C (1175°F) 595 “C (1100°F~ 565 “C (lOSO”F) 510°C (950 “F) 500 “C (925 “F) 470 “C (875 OF)
Source: AhlS 2759/l
490 / Heat Treaters
8822,8822H,
Guide
8822RH
Chemical Composition. 8822. AISI and UNS: 0.20 to 0.25 C. 0.75 to I .OO Mn.0.035 Pmas. 0.040 S max. 0. IS toO.3OSi. 0.40 too.70 Ni.O.40 to 0.60 Cr. 0.30 to 0.10 hlo. LJNS 888220 and SAE/AISI 88228: 0. I9 to 0.15 C. 0.70 to 1.05 Mn. 0.1s to 0.35 Si. 0.35 to 0.75 Ni. 0.35 to 0.65 Cr. 0.30 to 0.40 MO. SAE 8822RH: 0.20 to 0.25 C. 0.75 to I.00 Mn. 0.15 to 0.35 Si. 0.40 to 0.70 Ni, 0.40 to 0.60 Cr. 0.30 to 0.40 hlo Similar Steels (U.S. and/or Foreign). 8822. UNS G88220; SAE J-W. J770: (Ger.) DlN I .6543: (U.K.) B.S. XOS A 20.8822H. IJNS H8822O: ASThl A304 SAE 5407; t&r.) D[N 1.6543; iL1.K.) B.S. 805 A 20 Characteristics. A modification of 862OH. with a higher carbon range (same as 8632H) and a substantialI> higher mol!hdenum content to.30 to O.-W? as opposed to 0. IS to O.YG for 8620 and 8622H). This increase in molybdenum content results in a significant increase in hardenabilit). As-quenched hardness usuallq ranges from approximateI> -II to 47 HRC. Can be processed by carbonitriding. but usualI> is not used for producing parts that will be carbonitrided because most carbonitrided pans are relatively, small, and the higher hardenabilitj of 8822H is not required. Used princtpall) for producing parts L+ith heavy sections for which grades 8620H and 8622H do not have sufficient hardenability. such as heavy-duty gears and pinions. Such parts are subjected to carburiring treatments. Forges easil). and forging is often used to produce gear blanks and similar parts. Is readily heldable. although alloy steel practice should be used in welding to minimize susceptibility to weld cracking. Machinability is considered fairly good Forging. temperature
Heat to 1245 “C (2275 ‘F, maximum. Do not forge after of forging stock drops beIoN approximately 900 “C t IhSO “F)
Recommended Normalizing.
Heat Treating
Practice
Heat to 925 “C ( 16% “F). Cool in air
Annealing.
Structures ha\ ing best machinability are developed by normalizing: or by heating to 885 “C (I625 “F). cooling rapidly to 665 “C t I230 “F). and holding for -I h: or heat to 790 “C (l-i55 “F). cool rapidly to 665 “C t I230 “F). and hold for 8 h
Tempering.
Parts made from 50B14H should be tempered immediately after the) ha\ e been uniformI) quenched to near ambient temperature. Best practice is to place workpieces into the tempering furnace just before they ha\ e reached room temperature. ideall) u hen they are in the range of 38 to SO “C t 100 to 170 “F). Tempering temperature must be selected based upon the tinal desired hardness. After quenching to near ambient temperature. temper immediately at I SO “C (300 “F) or higher. The selection of tempering temperature depends on the required hardness or mechanical properties. 86SSH is sensitive to quench cracking. and tool steel practice should be observed In tempering. Parts should not be alloued to become too cold after quenching before they are placed in the tempering furnace. A uniform temperature of approximately 38 to SO “C ( 100 to I20 “F) is preferred. Temper all carburized or carbonitrided parts at IS0 “C (300 “F). and virtually no loss of case hardness results. If some decrease in hardness can be tolerated, toughness can be increased by tempering at somewhat higher temperatures; such as up to 7-60 “C (SO0 “F)
Case Hardening. scribed for 862OH
See carburizing
and carbonitriding
practices
de-
Alloy Steel / 491
Recommended l l l l l
Processing
Sequence
l
Forge Normalize Anneal (if required) Rough machine Semifinish machine allowing only grinding stoch. no more than IO? of the case depth per side for carburized parts. In most instances, carbonilrided parts are completely tinished in this skp
8822:
Approximate
Critical
point
OF
As, XCJ Ar, Ar, Sour~c: Republic
Carburize or carhonitride and quench Temper
8822:
Approximate
Core Hardness
Normalized at 1700 “F (925 “C) in 1.25-in. (31.8-mm) rounds; machined to 1-in. (25mm) or 0.540-in. (13.7-mm) rounds; pseudocarburized at 1700 “F (925 “C) for 8 h; box cooled to room temperature, reheated and oil quenched: tempered at 300 “F (150 “C); tested 0.505-in. (12.8-mm) rounds
Points Temperature
Critical
l
1330 I510 IUS II95 Steel
Reheat temperature “F T 1-m 1510 I590 17ool(1l ca)Qurnched
775 820 865 9251a1
Hardness, HB Heat treated in rounds 1 in. 0.540 in. (25 mm) (13.7 mm) 352 363 38X 388
from 17lXYF (925 ,;C, oficr psrudocmburiring
3s2 415 429 429 for8 h
8822, 8822H: Hardness vs Tempering Temperature. sents an average based on a fully quenched structure
8822: Cooling
Curve. Half cooling time. Source: Datasheet
l-60. Climax Molybdenum
Company
Repre-
492 / Heat Treaters
Guide
8822H: End-Quench Hardenability Distance from quenched surface ‘.~bin. mm
Hardness. HRC ma\ min
Distance from quenched surface I ‘16in. mm
Rardness. HRC may min
I 1
I su
so
13
13
20.5-l
31
;
4.74 3 16 6 32 7.90 9.-M
49 -18 -lb -13 40 37
42 39
IS I-l I6 18 70 ‘2
3s
2-l
2-l
23.70 22 I?. 3.28 28.44 3 I 60 34.76 37.92
30 30
33 29 27 75
4 5 h 7 x 9
I I.06 I’.hl
19 3 28
‘7 27
l-l.12
3-l
7-l
3
11.08
l5YO
33
23
28
U.‘-l
27
II
17.38
32
23
I2
IS96
31
22
30 32
47.m 50.56
27 27
IO
27
8822: CCT Diagram. Composition for AISI, constructional
alloy steel: 0.24 C, 0.95 Mn, 0.28 Si, 0.019 P, 0.025 S. 0.44 Ni, 0.31 MO. Steel was from commercial heat, and was austenitized at 850 “C (1560 “F) for 12 min. Determining heavy section hardenability was objective of study. Source: Datasheet I-60. Climax Molydbenum Company
Alloy
8822H: Hardenability
Curves. Heat-treating
(1700 OF). Austenitize:
925 “C (1700 “F)
Hardness wrposes I distance, nm I.5
limits for specification Eardness. Maximum
ERC hlinimum
SO 19 17 -IS II 38 3s 33 31 29 29 28 ‘7 17 27
Hardness limits for specification wrposes I distance, k,6i”.
3 I0 II IZ I3 I-l 15 I6 I8 !O 12 t-1 !6 !8 NJ
Hardness, hlauimum 50 49 -a 46 13 40 37 3s 31 33 31 31 31 30 30 29 29 23 27 27 17 27 27 27
HRC hlinimum
temperatures
recommended
by SAE. Normalize (for forged or rolled specimens
Steel / 493
only): 925 “C
1
494 / Heat Treaters
Guide
8822RH: Hardenability “C (1700 “F). Austenitize:
Hardness purposes J distance,
‘46io.
Curves. Heat-treating 925 “C (1700 “F)
limits for specification Hardness. Maximum
RRC Minimum
I
-19
-I4
4
I3
13 -IO 37 35 33 32 31 30 30 '9
I-1
28
IS 16 IX
28 27 27
35 31 29 27 26 2.5 2s 2-l ‘3 23 '3 22 22
20
26
22 2-l 26 28 30 32
26 26 26 25 25 25
5 h 7 8 9 I0 II
I2
Hardness purposes J distunce. mm
21
20
limits for specification Hardness, Maximum
HRC Minimum
I .5
49
4-l
3
5 7 9
18 -16 12 38
II
3.5
I3
33 32 29 27 27 26 36 L-5 ‘5
-I3 39 33 30 27 26 2s 23 22
IS
20 25 30 35
40 4s so
71
20
temperatures
recommended
by SAE. Normalize (for forged or rolled specimens
only): 925
Alloy Steel / 495
9260,926OH Chemical
Composition. 9260. MS1 and UNS: 0.56 to (X6-1C. 0.75 to I.00 Mn. 0.035 P max. 0.040 S max. I.80 to 2.30 Si. UNS H92600 and SAE/AISI926OH: 03.5 to 0.65 C.O.65 to 1.10 hln. 1.70 to 2.20 Si Similar
Steels (U.S. and/or Foreign). 9260. UNS G9?600: ASTM AZ9. AS9. AX?. A33 I ; SAE J-404, J4l2.5770: (Ger.) DfN I .0909: (Fr.) AFNOR 60 S 7,6l SC 7; (U.K.) B.S. 250 AS8.92608. UNS H92600: ASThl A304 SAE Jl268; (Ger.) DIN 1.0909; (Fr.) AFNOR 60s 7.61 SC 7: (U.K.) B.S. 30 A 58 Characteristics.
A special composition the only steel in the present AISI list where the silicon content il.7 to 2.2%) is high enough to he considered an alloy. Principal use is for heavy-duty springs. notably coil springs that are hot wound. Is nearly identtcal in composition to S-t. shock-resisting tool steel. 9160H is used for tooling as ~rell as nontooling applications. such as coining dies. L\ here impact resistance is important. As-quenched hardness can be expected to fall within the range of approximately 58 to 63 HRC. Hardenahility is considered fairly high
Forging. temperature
Annealing.
For a predominantly spheroidized structure (usually preferred). heat to 760 “C ( 1400 “F). then cool to 705 “C ( I300 “F). 31 a rate not to exceed 6 ‘C (IO “F) per h; or heat to 760 “C ( 1100 “F). cool rapidly to 665 “C ( I30 “F). and hold for IO h
Direct Hardening. hlartemperinp
Tempering.
After parts have been unifomtiy quenched to near ambient temperature. they should be placed in a tempering furnace immediately, preferably when their temperature is within the range of 38 to 50 “C (100 to I70 “F). The tempertng tempernture must be at least IS0 “C (300 “F). Higher tempering temperatures are usually used to develop maximum toughness in this steel
Recommended l l
Heat to 1205 “C (X00 “F) maximum. Do not forge after of forging stock drops below approximately 93 ‘C (I695 “F)
Normalizing.
l l
Practice
l
Heat to 900 “C ( 1650 “F). Cool in air
l
Recommended
Heat Treating
Austenitize at 870 “C ( 1600 “F). and quench in oil. is an nltemati\e process. Quenchants Include polymers
l
Processing
Sequence
Forge. or hot wind if producing springs Normalize Anneal Rough and semifinish machine (if applicable) .Austenitire and quench Temper Finish machine
9260: Isothermal Transformation
Diagram. Composition:
C. 0.82 Mn, 2.01 Si. 0.07 Cr. Austenitized Grain size: 6 to 7
at 870 “C (1600
0.62 “F).
496 / Heat Treaters
Guide
9260: Hardness vs Tempering Temperature. Composition: 0.55 to 0.65 C, 0.70 to 1 .OOMn. 1.80 to 2.20 Si. Forged at 1205 “C (2200 “F) maximum, furnace cooled from 815 to 925 “C (1500 to 1695 “F). Maximum annealed hardness, 229 HB. Hardness when normalized in test size, 302 HB. Normalized at 900 “C (1650 “F), quenched in oil from 870 “C (1600 “F), tempered for 2 h. Source: Republic Steel
9260H: End-Quench Hardenability Dktance from quenched surface ‘&in. mm 1 2 3 4 5 6
1.58 3.16 4.74 6.32 7.90 9.48
7 8 9 10 11 12
Hardness, HRC mas min
Distance from quenched surface &in. mm
Hardness, HRC may min
65 64 63 62
60 60 57 53 46 41
13 14 15 16 18 20
20.54 22.12 23.70 25.28 28.44 31.60
4.5 43 42 40 38 37
33 33 32 32 31 31
11.06 12.64 14.22
60 58 55
38 36 36
22 24 26
34.76 37.92 41.08
36 36 35
30 30 29
15.80 17.38 18.96
52 49 47
35 34 34
28 30 32
44.24 47.40 50.56
35 35 34
29 28 28
9260: End-Quench
Hardenability.
Mn, 2.01 Si. 0.07 Cr. Austenitized 6to7
Composition: 0.62 C, 0.82 at 870 “C (1600 “F). Grain size:
Alloy Steel / 497
9260H: Hardenability
Curves. Heat-treating
(1650 “F). Austenitize:
870 “C (1600 “F)
iardness wrposes I dbtancc. nm
limits for specification Hardness, Maximum
HRC Minimum
.:,
60 60 SY SO 42 38 36 35 33 32 31 30 29 28 28
6.5 63 62 60 5x 54 47 40 38 37 36 3.i 35
iardness wrposes I distance. 46 in.
0 I 2 3 4 5 6 8 :o 12 !4 I6 8 IO I2
limits for specification Hardness, Maximum
65 64 63 62 60 X3 5s 52 49 47 45 43 42 40 38 37 36 36 35 35 3s 34
HRC lllinimum 60 60 57 53 46 41 38 36 36 35 31 3-1 33 33 32 32 31 31 30 30 29 29 28 2x
temperatures
recommended
by SAE. Normalize (for forged or rolled specimens
only): 900 “C
498 / Heat Treaters
9260: CCT Diagram. method)
Guide
Composition:
0.57 C, 0.91 Mn, 1.95 Si. Grain size: 7. Austenitized
at 870 “C (1600 “F) (using interrupted
Jominy
498 / Heat Treaters Guide
931 OH, 931 ORH Chemical
COf’IIpOSitiOn.
UNS H93100 and SAE/AISI 9310H: 0.07
to013 C. 0.40 to0.70 Mn.0.15 to030 Si. 2.95 to 3.55 Ni. 1.00 to I.-IS Cr. 0.08 to 0. IS hlo. SAE 9310RH: 0.08 to 0. I3 C. 0.45 to 0.65 hln. 0. IS to 0.35 Si. 3.00 to 3.50 Ni. I .OO to I .-IO Cr. 0.08 to 0.15 MO
Similar Steels (U.S. and/or Foreign).
UNS
G93 100:
ASTM
.A3(H: SAE Jl26X
Characteristics. A relati\elq high-allo!. high-qualit). and high-hardenability case hardening steel. Uwally carburired. Because of its relatimely low carbon content, as-quenched hardness is not usually higher than approximately 32 to 38 HRC. depending on whether the carbon is near the lo\\ side or the high side of the allowable range. Hardenabilit~. ho\bever. is high. Used for such applications as premium quality gears. such as aircraft engines and pinions for which high hardenability and an unusualI) high degree of toughness are mandator). Relatively expensive and has a high nickel content. b hich can be a scarce allo>. The use of 93 IOH has gradualI) dsclined in favor of higher carbon. lower allo) grades of carburizing steels. Can be case hardened by carbonitriding. but economics usually exclude the use of 93 IOH for parts that would require carbonitriding
Annealing.
Because of the sluggish transformation characteristics of this steel. con\ entional annealing is not usually practical. A better means of obtaining a spheroidized structure in 93 IOH is bj tempering for approximately I8 h at a subcritical temperature. usually 600 “C ( I I IO “F)
Tempering.
Temper all carburizrd parts at IS0 “C (300 “FL and virtualI> no loss of case hardness results. If some decrease in hardness can be tolerated. toughness can be increased b) tempering at somewhat higher temperatures. up to 260 ‘C (SO0 “F)
Case Hardening. uum carburizing. able processes
Recommended l l l
Forging.
Heat to 1260 “C (2300 “F) maximum. Do not forge after temperature of forging stock drops below approximateI) 925 “C (16% ‘Fr
Recommended Heat Treating Practice Normalizing. Heat to 92s “C ( I695 “FL Cool in air
l l
l l
See carburizing practice described for 8620H. Vacion nitriding. austempenng. and martempering are suit-
Processing
Sequence
Forge Normalize Anneal (if required) Rough machine Semifinish machine. allowing only grinding the case depth per side for carburizcd parts Carburize and quench Temper
stock. no more than 10% of
Alloy Steel I499
9310H: Hardness vs Tempering Temperature. average based on a fully quenched structure
9310H: End-Quench Distance frum quenched surface 1/l~in. mm
1 2 3 4 5 6
Hardenability
Elardness, ARC max min
1.58 3.16
4.74 6.32
1.90 9.48
I
11.06
8 9
12.64 14.22
10 11
15.80 17.38
12
18.96
43 43 43 42 42 42 42 41 40 40 39 38
Diagram.
36 35 35 34 32 31 30 29 28 27 21 26
Austenitized
Distance From quenched surface 916 in. mm 13 14 15 16 18 20 22 24 26 28 30 32
20.54 22.12 23.10 25.28 28.44 31.60 34.16 37.92 41.08 44.24 47.40 50.56
Hardness, HRC mar min 31 36 36 35 35 35 34 34 34 34 33 33
26 26 26 26 26 25 25 25 25 25 24 24
20 min at 829 “C (1525 “F). Source: Climax Molybdenum
Company
Represents
an
500 / Heat Treaters
Guide
9310: Microstructures. Note: For (a to g), specimens were gas carburized at 925 to 940 “C (1695 to 1725 “F) for 4 h in a pit-type furnace, furnace cooled, austenitized at 815 to 830 “C (1500 to 1525 “F), oil quenched, and tempered at 150 “C (300 “F) for4 h. Case carbon contents vary because of variations in the carbon potential of the carburizing atmosphere. (a) 2% nital, 500x. Gas carburized to a maximum case carbon content of 0.60% (lean). (b) 296 nital, 500x. Gas carburized to a maximum case carbon content of 0.85%. (c) 2% nital, 500x. Gas carburized to a maximum case carbon content of 0.95?& (optimum). (d) 2% nital, 500x. Gas carburized to a maxrmum case carbon content of 1.05%. (e) 2% nital, 500x. Gas carburized to a maximum case carbon content of 1.1046. (f) 2% nital, 500x. Gas carburized to a maximum case carbon content of 1.20%. (g) Picral. 200x. Normalized by austenitizing 2 h at 885 “C (1625 “F) and cooling in still air. Scattered carbide particles and unresolved pearlite in a matrix of ferrite (light constituent). (h) 396 nital, 500x. Annealed by austenitizing 2 h at 885 “C (1625 “F) and cooling slowly in a furnace. Scattered carbide particles (dark constituent) in a matrix of ferrite (light constituent)
Alloy Steel / 501
9310H: Hardenability
Curves. Heat-treating
(1700 “F). Austenitize:
845 “C (1555 “F)
iardness wrposes distance. qm
5
,l 13 15 !O !5 30 15 to $5 $0
iardness wrposes distance.
&ill.
0 1 2 3 14 15 16 18 !O !2 !4 !6 18 $0 2
limits for specification Hardness, HRC hlavimum Minimum 43 43 43 43 43 42 41 40 38 36 35 35 34 34 33
36 35 34 33 31 30 28 27 26 25 25 25 25 24 24
limits for specification Hardness. HRC Maximum hlinimum 43 43 43 42 42 42 42 41 40 40 39 38 31 36 36 35 35 35 34 34 34 34 33 33
36 35 35 34 32 31 30 29 28 27 27 26 26 26 26 26 26 25 25 25 25 25 24 24
temperatures
recommended
by SAE. Normalize (for forged or rolled specimens
only): 925 “C
502 / Heat Treaters
Guide
9310RH: Hardenability Curves. Heat-treating “C (1700 “F). Austenitiie: 845 “C (1555 “F) Hardness purposes
limits
J distance. I,16iIl.
for specification Eardness, Maximum
HRC Minimum
-IT! 42 42 II -II 40 4) 39 38 37 37 36 3s 34 31 33 33 3’ ;:! 32 32 32 31 31
Hardness purposes J distance. mm I .s 1
limits
37 36 36 3s 34 33 32 31 30 29 29 18 28 2x 28 17 27 26 -76 26 26 26 2s 25
for specification Hardness, Maximum -I? -I? 42 -II -IO -IO 39 37 35 33 32 32 3’ ;I 31
HRC Minimum 37 36 36 3s 33 3’ 3; ‘9 28 27 xl 76 26 25 3
temperatures
recommended
by SAE. Normalize (for forged or rolled specimens
only): 925
1
Alloy Steel / 503
94Bl5,94Bl5H Chemical
Composition.
9JB15. AM:
0.13
to
Recommended
0.18 C. 0.75 to I .OO
Heat Treating
Practice
hln. 0.035 P mas. O.O-tO S max. 0.30 to 0.60 Ni. 0.30 to 0.50 Cr. 0.08 to 0. IS MO. 0.0005 B min. UTVS: 0. I? to 0. I8 C. 0.75 to I.00 hln. 0.035 P ma~.0.0-10Smax.0.15to0.30Si.0.30to0.60Ni.0.30to0.50Cr.0.08to 0. IS MO. 0.0005 B min. IJNS H94151 and SAE/AISI 9JBlSH: 0. I? to 0.18 C. 0.70 to I.05 Mn. 0.15 to 0.35 Si. 0.35 to 0.65 Ni. 0.25 to 0.55 Cr. 0.08 to 0. I5 MO. B (can be expected to he 0.0005 to 0.003 percent)
For a predominantly pearlitic structure. heat to 900 “C ( 1650 “F). cool rapidly to 665 “C ( I230 “F) and hold for 5 h. For a predominantly spheroidized structure. heat to 800 “C ( 1175 “F), cool rapidly to 665 “C t 1330 “F). and hold for IO h
Similar
Tempering.
AMS
Steels (U.S. and/or
6375
ASTM
A;
ASTM
4519:
Foreign).
SAE
94B15. l!NS W-I IS I: J-KJ-L 1770. 94B15H. 1rNS H9-tlSl:
A304: SAE J I268
Characteristics. One of the tuo principal boron-containing _erades used for case hardening, either carburizing or carbonitriding. Dependmg on the precise carbon content within the allowable range. as-quenched hardness (without case) usually ranges from 35 to 40 HRC. However. because of the boron addition. the hardenability of this grade is higher than that 01 an X6OOH grade of similar carbon content. although the ranges of Ni. Cr. and MO are lower for 94B I5H. Used for carburized parts ibhich have heavy sections and need the higher hardenability. Cost is generally less than that of a higher alloy grade not containing boron Nhich would be required to provide the same hardenahility Forging. temperature
Heat to 1245 “C (27-75 “F) maximum. Do not forge after of forging stock drops helo\{ approximately 900 “C t 1650 “F)
Normalizing.
Hsat
to 93.5 “C t 1695 “F). Cool
in air
Annealing.
Temper all carburized or carbonitrided parts at I SO “C (300 “F), and virtually no loss of case hardness results. If some decrease in hardness can be tolerated. toughness can he increased by tempering at somewhat higher temperatures. up to 260 ‘C (SO0 “F)
Case Hardening.
See carburizing
and carbonitriding
Processing
Sequence
Recommended l
Distance &om quenched surface 1,‘,6 in. mm
Hardenability
Bardness. q RC min max
Distance From quenched surface ‘116 in. mm
Bardness, BRC mltY
7 3 4 5 6
I
I.58 3.16 4.7-l 6.32 7.90 9.18
IS 1s 4-l 44 13 12
38 38 37 36 32 28
13 II IS I6 18 70
20 s-l 12.12 13.70 15.28 28 +I 31.60
30 29 28 27 ‘6
7 8 9
I I.06 12.64 14.7-7
10 38 36
2s 13 II
2’ 2-l 26
34 76 37.92 11.08
24 23 23
IO
IS.80
3-l
20
28
44.2-l
22
II I?
17.38 I&%
33 31
30 3’
47.40 SO.56
27 22
I5
de-
l l l l l
l
Forge Normalize Anneal (if required) Rough machine Carburize or carhonitride and quench Semifinish machine. allowing only grinding smck, no more than IO4 of the case depth per side for carbuhzed parts. In most instances. carbonitrided parts~are’completely finished in this step Temper
94815,94615H: HardnessvsTemparingTemperature. sents an average based on a fully quenched structure
94B15H: End-Quench
processes
scribed for 8630H
Repre-
504 / Heat Treaters
Guide
94615H: Hardenability
Curves. Heat-treating
“C (1700 “F). Austenitize:
925 “C (1700 “F)
Hardness purposes I distance, nm 1.5
Hardness wrposes I distance. j/16in.
1
limits for specification Hardness. HRC Maximum Minimum 45 45 45 44 42 40 38 36 31 28 26 24 23 22 22
limits for specification Hardness, HRC hlinimum hlasimum 45 45 44 44 43 42 40
IO II 12 13 14 1s 16 18 20 22 24 26 28 30 32
38 38 37 34 30 26 22 20
38 36 34 33 31 30 29 28 27 26 25 24 23 23 22 22 22
38 38 37 36 32 28 25 23 21 20
temperatures
recommended
by SAE. Normalize (for forged or rolled specimens
only): 925
Alloy Steel / 505
94Bl7,94Bl7H Chemical
Composition.
94B17. AISI: 0.1s 100.10 C. 0.75 to I .OO
hln.0.035 Pmax.0.010Smax.0.15 to0.30Si.0.30to0.60Ni.0.3Oto0.SC) C-r, 0.08 to 0.15 MO, 0.0005 to 0.003 8. UNS: 0.15 to 0.20 C. 0.75 IO 1.00 hln,0.03SPmax.0.0~0Smax,O.lSto0.30Si,0.30to0.60Ni.0.30to0.S0 Cr. 0.08 to 0. IS MO. O.CHJOSB min. UNS A94171 and SAE/AISI 9JB17H: 0.1-l to 0.20 C, 0.70 to I.05 hln. 0.15 IO 0.35 Si. O.?S to 0.6s Ni. O.ZS to 0.55 Cr. 0.08 to 0. IS MO. B (can be expected to be 0.0005 IO 0.003 percent)
Similar
Steels (U.S. and/or
AMS 6375: ASTM ASl9: ASTM A30-l: SAE J I268
Foreign).
9JB17. LINS G9-l I7 I :
SAE J-IO-I. 5770. 94B17H.
UNS
H49-ll71:
Annealing.
For a predominantly pearlitic structure, heat to 900 “C ( 1650 “F). cool rapidly to 665 “C ( I230 “F). and hold for -1 h. For a predominantly sphsroidized structure, heat to 800 “C (l-l75 “F). cool rapidly to 665 “C ( I?30 “F). and hold for IO h
Tempering.
Temper all carburized or carbonitrided parts at I50 “C (300 “F). and virtually no loss of case hardness results. If some decrease in hardness can be tolerated. toughness can be increased by tempering at somewhat higher temperatures, up to 260 “C (500 “F)
Case Hardening.
Characteristics.
The compositions of 91B I7H and 9AB ISH are identical, escept for a slightly higher carbon range from 9dB l7H. The characteristics of these two pades are essentially the same. Because of the higher carbon range, as-quenched hardness range without case is slightlq higher for 9-lB l7H. approximate11 37 to -lZ HRC. The hardenabilit) pattern for 9-1Bl7H is the same as for 91BlSH. except the entire band for 9-+Bl7H is shifted upward because of the higher carbon content. Grade 91Bl7H is often used instead of 91B I SH I\ hen a higher core hardness is needed for carburized parts
Recommended l l l l l
Forging.
Heat to IX5 “C (‘775 ‘F) mzsimum. Do not forge atier temperature of forging stock drops belo\\ approximately 900 “C I 1650 ‘F) l
Recommended Normalizing.
Heat Treating
Heat to 97-S “C (I695
Practice
See carburizing
and carbonitriding
processes
de-
scribed for 8610H
l
Processing
Sequence
Forge Normalize .Anncal (if required) Rough machine Semifinish machine. alloying only grinding stock. no more than IOQ of the case depth per side for carburized parts. In most instances, carbonitrided parts are completely finished in this step Carburize or carbonitride and quench Temper
“F). Cool in air
94617: Isothermal
Transformation
Diagram. Composition:
O.l9C, 0.77 Mn, 0.42 Ni, 0.4OCr, 0.12 MO, 0.0018B. at 925 “C (1695 “F). Grain stze: 7 to 8
Austenitized
94817,94617H:
Hardness vs Tempering Temperature. Repre-
sents an average
based
on a fully quenched
structure
506 / Heat Treaters
Guide
94B17H: Hardenability
Curves. Heat-treating
“C (1700 “F). Austenitize:
Hardness surposes I distance, nm
I .5 1
925 “C (1700 “F)
limits for specification Hardness, HRC hlinimum hlaximum 46 46
39 39 38 36 31 26 24 22
46 45 44 43 41 39 34 30 28 26 25 24
hardness wrposes I distance, /I6 in.
.
limits for specification Hardness,
hladmum 46
IO II 12 13 14 I5 I6 I8 TO 12 !4 !6 !8 IO )2
46 45 45 44 43 42 41 40 38 36 34 33 32 31 30 28 21 26 25 24 24 23 23
HRC hlinimum 39 39 38 37 34 29 26 24 23 21 20
temperatures
recommended
by SAE. Normalize (for forged or rolled specimens
only): 925
Alloy Steel / 507
94817H: End-Quench Hardenability Distance from quenched surface l/16 in. mm
Hardness, HRC max min
-l 5 6 7
I S8 3.16 4.7-l 6.33 7.90 9.18 Il.06
46 16 35 1s J-4 43 -I?
39 39 38 37 3-l 29 26
8 9 I0 II I2
I2.6-l I-l.22 IS.80 17 38 I8.%
II 40 38 36 3-l
7-l 23 21 20
I ? 3
Distance from quenched surface 1, mm 46 in. I3 I-l IS I6 I8 20
Hardness, HRC max
22
10.51 2.12 23.70 2.5 33 28.4-l 31.60 31.76
3.1 32 31 30 28 27 26
21 26 7-8 30 32
37.92 41.08 -u.Ll 17.40 SO.56
2.5 L-l 2-i 23 23
94817: End-Quench Hardenability.
Composition: 0.19 C, 0.77 Mn, 0.42 Ni, 0.40 Cr, 0.12 MO, 0.0018 B. Austenitized at 925 “C (1695 “F). Grain size: 7 to 8
Alloy Steel / 507
94B30,94B30H Chemical
Composition.
93B30. AISI: 0.28
to
0.33 C. 0.75
to
I .OO
Mn.0.03SPn~ax,0.~0Sn~~~.0.lSto0.30Si.0.?0to0.60Ni.0.3OtoO.S0 Cr. 0.08 to 0. IS Mo. 0.0005 to 0.003 B. UNS: 0.28 to 0.33 C. 0.75 to 1.00 hln.0.03SPn~ax.0.~0Sn~~~.0.lSto0.3OSi.O.?Oto0.60Ni.0.30to0.S0 Cr. 0.08 to 0. IS MO. 0.0005 B min. UNS H9-1301 and SAE/AISI 91B30H: 0.27 to 0.33 C. 0.70 to I.05 Mn, 0.15 to 0.35 Si. 0.25 to 0.65 Ni. 0.25 to 0.55 Cr. 0.08 to 0. IS MO. B (can be expected to be 0.0005 to 0.003 percent)
Similar
Steels (U.S. and/or Foreign).
ASTM ASl9: SAE 1104, JJl2. A304 SAE J I268
93B30. LlNS G9-1301; 1JNS H94301; ASTM
J770. 9JB30H.
Characteristics. Clearly demonstrates the effects of boron upon hardenability. 91B30H is nearly identical with 86B?OH. although the alloy ranges (Ni. Cr. Mo) are slightly lower for 91B30H. The hardenability because of the boron addition is nearly as high for 86B?OH. As-quenched hardness, which is controlled mainly by carbon content. is the same for 94B30H as for 86B30H. approximately 46 to 52 HRC
Forging. temperature
Heat to 1230 ‘C (2250 “F) maximum. Do not forge after of forging stock drops below approximately 925 “C (I695 “F)
Recommended Normalizing.
Heat Treating
Practice
Heat to 900 “C t 1650 “F). Cool in ait
Annealing.
For a predominantly pearlitic structure. heat to 845 “C ( IS55 “F). cool slowly to 730 “C t I ?SOW~F). then cool to 640 “C (I I85 “F). at a rate not to esceed I I “C (20 “F) per h: or heat to 845 “C ( IS55 “F), cool rapidly. to 665 “C (I230 “FL and hold for 7 h. For a predominantly spherotdired structure. heat to 760 “C (1300 “F), cool rapidly to 730 “C t I350 “FL then cool to 650 “C t I200 “F), at a rate not to exceed 6 “C ( IO “F) per h: or heat to 760 “C ( 1100 “F). cool rapidly to 665 “C ( I230 “F). and hold for IO h
Hardening.
Austsnitire
Tempering.
Parts should be tempered immediately after quenching \c hich will pro\ ide the required hardness
the temperature
at 870 “C ( 1600 “FL and quench in oil at
508 / Heat Treaters
Guide
Processing
Recommended
Sequence
l l
l l l
Forge Normalize r\nneal
l l
Rough and semifinish machine Austenitize and wench Temper Finish machine
94830: Hardness vs Tempering Temperature. Composition: 0.28 to 0.33 C. 0.75 to 1 .OO Mn, 0.040 P max, 0.040 S max, 0.20 to0.35Si,0.30to0.60Ni,0.30to0.50Cr,0.08to0.15Mo,0.0005 B min. Approximate critical points: AC,, 720 “C (1330 “F); AC,, 805 “C (1480”F);Ar,, 750°C (1380”F);Ar,, 655°C (1210°F). Recommended themal treatment: forge at 1230 “C (2250 “F), anneal at 815 to 870 “C (1500 to 1600 “F) for a maximum hardness of 174 HB, normalize at 870 to 925 “C (1600 to 1695 “F) for an approximate hardness of 217 HB. quench from 855 to 885 “C (1570 to 1625 “F) in oil. Test specimens were normalized at 900 “C (1650 “F), quenched from 870 “C (1600 “F) in oil, tempered at 56 “C (100 “F) intervals in 13.7 mm (0.540 in.) rounds. Tested in 12.8 mm (0.505 in.) rounds. Source: Republic Steel
94B30H: End-Quench Distance from quenched W-fNe
‘[bin.
mm
Hardenability
Hardness, HRC min ma\:
Distance from quenched surface ’ 16 in. mm
Hardness. HRC min may
I 2
I SY 3 16
Sh 56
19 1Y
I! I-I
20.54 22.12
SO 19
30 2Y
3 4 s 6 7
1.7-t 6 32 7.90 9.33 I I.06 12.64 I-I.22
ss ss 51 51 5.; 53 s?.
48 48 -I7 46 u 42 39
IS I6 I8 20 22 2-l 26
‘3.70 15.28 ‘8.44 31 60 31.76 37.92 -II 0s
4x 46 4.4 12 40 38 37
28 ‘7 2s 24 23 23 22
I0
IS.XrJ
52
II I2
I7 38 I X.96
51 Sl
37 31 32
28 30 32
44.21 47.10 so 56
3s 3-1 3-t
21 21 20
x
9
Alloy Steel / 509
94B30H: Hardenability “C (1650 “F). Austenitize:
Hardness wrposes I distance. nm ..5
3 11
13 15 !O !5 SO $5 lo 15 50
I distance, !& in.
2 3 Q 5 6
7 8 9 10 11 12 13 14 15 16 18 20 22 24 26 28 30 32
Curves. Heat-treating 870 “C (1600 “F)
limits for specification Hardness, hlaximum
HRC Minimum
56
49
56 56 55 55 54 53 53 51 47 43 40 31 36 34
49 48 47 46 44 41 38 31 26 24 23 22 21 20
Hardness, hlaximum
56 56 55 55 54 54 53 53 52 52 51 51 50 49 48 46 44 42 40 38 37 35 34 34
HRC hlinimum 49
49 48 48 47 46 44 42 39 37 34 32 30 29 28 21 25 24 23 23 22 21 21 20
temperatures
recommended
by SAE. Normalize (for forged or rolled specimens
only): 900
510 / Heat Treaters
Guide
No. 5317 0.50 C. 0.50 Mn. 0.25 Si. I.75 Ni. I .OO Cr
Hardening.
A cold melt. grain controlled. electric furnace steel heat treatable to combination of hardness and toughness for machine parts in t\\o classes:
Tempering.
Chemical
Composition.
Characteristics.
Hard tempering group. for gears and other hard parts. hardened and tempered between 105 to 345 “C WJO to 655 “F) 2. Tough tempering group for parts such as shafts. hardened and tempered between 370 to 595 “C (700 to I IO5 “F)
Heat to 790 to 8 IS “C f I.455 to 1500 “F). and quench in oil
Temperature used depends on service conditions. Lower temperatures (see table beloa ) are used when greater surface hardness and strength are required. Higher temperatures are used for greater toughness
I
Steel has no special tendencies to decarburize. Machinabilit) is 65 to 75 percent of I percent carbon. Mater hardening tool steel. or about SO percent that of BIII’
Forging.
Heat to I I SO “C i2 100 “F) maximum. Air cool in dQ place. Do not forge after temperature of forging stock drops belo\i approximate11 8 I5 “Ctl5OO”F)
Recommended Normalizing.
Heat Treating
Practice
Heat to 815 to 900 “C ( 1555 to 1650 “FJ. Cool in air
Annealing. Pack steel in container. usmg neutral packing compound. or treat in controlled atmosphere furnace. Heat parts to 760 “C ( 1400 “F). cool slowly in furnace at a rate not to exceed I I “C (20 “F) per h until furnace is black. and may then be turned off and allowed to cool naturally. Parts have maximum hardness of 201 HB
No. 5-317:
Effect of Tempering
Tempering temperature OF T As quenched 300 350 -u?o 150 500 540
600 700 800 900 loo0 1100 3 mm ( I in. I. seaion.
As quenched 149
177 20-i 232 260 288 316 371 4’7 J82 538 593 oil quenched From 790 “C I 1450 “Fb
Ruckwell ‘C” 56 56 55 54 53 53 52 SO 46 -l-t 40 35 31
510 / Heat Treaters
Guide
CRB-7 MO. I .OOV. 0.25 Cb
soak forging at this temperature until temperature of forging is uniform. then shut off heat. let forging cool in furnace. Annealing follows
Characteristics.
Recommended
Chemical
Composition.
I.10 C. 0.10 hln. 0.30 Si. I-I.00 Cr. 2.00
A corrosion resistant. \rear resistant. and secondq hardening. high temperature bearing steel. which has high heat treated hardness that is maintained at elevated temperatures
Forging.
Preheat slou ly to 815 to 870 “C ( IS00 to 1600 “Ft. then increase furnace temperature to full heat of I095 to I I?0 YI (2005 to 2050 “F). Do not forge after temperature of forging stock drops below approsimatell 980 “C ( I795 “F). Can be reheated as often as necessary. Slow cool forgings IO room temperature m dq ash. vemticulite. or in a furnace \\ hen forging cooling. First set furnace at about 760 to 790 “C t l-t00 to 1455 “Ft.
CRB-7:
Effect of Tempering
Rnckwell T
r\s quenched + reirigrratrd 300 l-l9 100 mo hfxl 700 800 900 loofl I lcil
Annealing.
Practice
Not recommended Tno methods are available:
I Pack parts in container. using clean. cast iron borings 1. hned in a controlled atmosphere furnace with a dew point of I .S to 8 “C (35 to IS “FJ. Heat unifomtl~ to 870 to 900 ‘C (I600 to 1650 “F), cool slowly in furnace to about 595 “C t I IO5 “F) at a rate not to exceed 6 “C (20 “F) per h. air cool to room temperature.
Temperatures
Tempering temperature OF
Normalizing.
Heat Treating
‘0-l 160 316 371 427 3x2 S38 SY3
CRB-7:
C
Elevated
Hardness 63.5 61.0 59.5 58.0 5X.0 58.0 605 62 0 53 s
Rockwell Eardnes
260 316 371 127 482 538
62.5 59.0 58.5 58.0 57.0 56.0 51.0
Room temperature 500 600 700 800 900 1000
“FL and
Hardness
DC
Test temperature OF
64.0
Parts were oil quenched from I I SO “C (2 IO0 ‘FL refrigwatrd BI -7S ‘C f-105 tempered I h a~ temperature. Source. Carpenter Technolog? Corporation
Temperature
C
Hardnesses uere measured on specimrw heat treated as follows: salt quenched from I ISOYZ t Z IO0 “F) to Ml ‘C t 1000°F~ equaltzcd, then aircooled toroom temperature, streisrelievedat ISO”C(3Ot”Fb I h,refrigcratedat-7S”C(-105”F).douhletempered 2 + 2 hat 525 “C (975 “F). Source: CarpznterTechnolo~ Corporation
Alloy Steel / 511
Average hardness of parts will be 2-I I HB
Hardening. Parts are treated in neutral salt baths or in controlled atmosphere furnaces. For the latter, a dew point of - I7 “C (+ IO “F) is suggested. For the furnace procedure. oarts are preheated to 800 to 830 “C t 1375 to IS3 “F). then transferred to a superheating furnace maintained at I I-IO to I IS5 “C (2085 to 21 IO “F). Small parts may be oil quenched to room temperature. Preferred practice is to harden by quenching in molten salt at
a temperature of S-IO to 595 “C ( 1000 to I 100 “F). followed by air cooling to room temperature. Parts are then stress relief tempered at -ISO “C (3% “F) for I h. For higher hardness and dimensional stability, parts are allowed to return to room temperature before tempering
Tempering.
Double tempering is recommended for maximum hardness and dimensional stability. Parts are allowed to return to room temperature before tempering
Tool Steels Introduction Tool steels represent a small, but mlportant segment of the total production of steel. These steels are made and processed IO meet extremeI> high standards of qualiy control and are used principally for tools, dies. and components of mechamcal de\ ices that demand steels with special properties. Well over IO0 different kinds of tool steels are produced at the present time. and if all the trade names Mere added together. the total \\ould far exceed 100. Tool steels vary in composition from plain carbon steels containing carbon with no significant amounts of alloying iron and up to 1.X elements. to veq highly alloyed grades. in which the total allo) content approaches 50% Many tool steels are identical in composition to carbon and alloy steels that are produced in large tonnages. The ditierences lie in the small amount produced and the high level ofqualitj control in\ol\ed. Classification of Tool Steels. Tool steels do not lend themselves to the type of classification used by the Societ) of Automotive Engineers (SAE) and the American Iron and Steel Institute (AISI) for low-alloy steels. because in these systems an entire series of steels is defined numerically, based upon a variation of carbon content alone. \\Iile some carbon tool steels and low-alloy tool steels are made in a u ide range of carbon contents. most of the higher alloyed tool steels have a compamlively narrow carbon range makmg such a classiticatlon meaningless. Instead a mixed classification system is used uith tool steels. in M hich some steels are grouped hy use. others by composition or bq certain mechanical properties. and still others by the method of heat treatment (precIseI) hy the quenching technique). High-speed steels are grouped together because the) have certain common properties, the water-hardening steels because the) are hardened in a common manner. the hot \\ork steels because they have certain common properties, and the high-carbon. high-chromium steels because they have similar compositions and similar applications. The American Iron and Steel Institute System. The table at the end of this introduction includes compositions for most of the proprietary tool steels-Unified Numbering System (UNS) specifications are also given. Elements are listed in nominal amounts which ma) vary someis hat for different tool steel producers. U’hen heat treating shops receive tools for heat treatment that are identified only by proprictq name. the AISI identiticatton should heobtained before attempting to perform an! heat treating operation. A number of grades ha\e heen deleted from the AISI list because thsj were no longer manufactured in signiticant quantities. and the steels listed in the table cover every conceivable tooling requirement. Statistics show that over S(Y? of the total tonnage of tool steels produced is confined to no more than about I? or I5 of the compositions included in the Table. The grouping of tool steels published bq AISI has proved MoorlaMe. and the nine main groups and their corresponding sjmhols are giLen as follows~ Identifying symbol
Name IVater-hardening
1001 SltXlj
M
Shock-resisting tool steels Oil-hardrmngsold work tool ~IZZIZ Air-hardening. medium-alloy cold \rorh tool SIeelb High-carbon, high-chromium cold \rorli 1o4 steels
S 0 .A D
hlold steels
P H
Hot #ark tool steels. chromium, tungsvn. and mol)bdcnum Tungsten high-speed rool su&
T
hlol) bdenum high-speed tool seeIs
hl
Water-Hardening Tool Steels. The grades listed in the Table under the symbol IV are essentially c,arbon steels and are among the least expensive of tool steels. They must he water quenched to attain the necessary hardness, and except in veq small sizes, will harden with a hard case and a soft core. These steels ma) be used for a wide variety of tools. but the) do have limitations. H’ steels are available in a range of carbon contents. and the selcctlon of carbon content is based upon whether maximum toughness or mrt\imum wear resistance is the more important. A lower carbon content pro\ ides maximum toughness. Although all W steels have rslntivel~ low hardenabilitl. these grades are usually available as shallow. medium. or deep hardening. and this property is controlled by the manufacturer. Of the three compositions listed. WI is the most extensively used. Shock-Resisting Tool Steels. Steels are listed under the symhol S. As ma) be noted in the Table. the alloy content in these steels varies uidelj, resulting in a \yidc variation in hardenability among the grades. However. all S steels are intended for applications that require extreme chisels. toughness including punches, shear knives. and air-operated Grades Sl (tungsten bearing), and SS (high silicon) are most widely used. Oil-Hardening, Cold Work Tool Steels. These grades are listed in the table under the symbol 0. As agroup, the hardenability ofthese steels is much higher than that of the W grades: therefore, they can be hardened hq quenching in oil. Grade 01 is by far the most popular of this group. A portion of the carbon in 06 is in the form ofgraphite. which allows helter machinability, a factor HI making intricate dies. In addition. the graphite particles in its microstructure provide a built-in lubricant, giving these steels a better die life for deep dra\b ing operations. 07 is sometimes used for certain dies where it is essential to retain keen cutting edges hecause these steels have a higher carbon and the tungsten addition. Air-Hardening,
Medium-Alloy
Cold Work Tool Steels.
The cold work tool steels listed under the symbol A cover a wide range of carbon and alloy contents, but all habe high hardenability andexhibit a high degree of dimensional stahilit) in heat treatment. The low-carbon types, A8 and A9. offer greater shock resistance than the other steels in this group, but are lo\rer in their wear resistance. Type .A7, which has high carbon and vanadium contents. exhibits maximum abrasion resistance, but should be restricted to applications where toughness is not a prime consideration. As ma) be noted in the Table, A IO is also a graphitic steel, and it has properties similar IO 06 except that A IO is higher in hardenability. Of the grades listed in this group. A). is the most wideI> used.
High-Carbon,
High-Chromium
Cold Work Tool Steels.
The cold work steels listed under the symbol D are all characterized by a high carbon content t I .S to 2% ) and a nominal 12.08 chromium content. T> pes containing mol> bdenum can he air hardened. All grades of this group have extremely high resistance to abrasive wear, which increases as the carbon and vanadium increase. Grade D7 is one of the most abrasion-resistrng steels knon n. and it is often used for such rigorous applications as brick molds. Ho\\e\er. the characteristics uhich provide its abrasion resistance make it \ery difficult to machine or grind. Grade D5, because of its cobalt addition. can he used for hot fomting or shearing operations at tempemtures up to 480 “C (895 “F). Of the five grades listed in this group, D2 is the most \I idsI> used. Low-Alloy, Special-Purpose Tool Steels. The tool steels listed under the symbol L cover a wide range of alloy content and mechanical properties. They are wideI> used for die components and machinery parts. Both L6 and the lo\rcr carbon versions of L? are often used for
514 / Heat Treaters
Guide
Classification
and approximate
AISI
UNS No.
Water-hardening WI W2 W5
C
Oil-hardening,
Air-hardening, A2 A3 Al A6 A7 A8 A9 AlO
High-carbon, D? D3 M DS D7
Identifying elements, 70 v If
hlo
co
Ni
025
2 so
1.50 0.80 I.10
I In 2.00 2.25
0 w, 0.40 0.40 I.40
I.50 3.25
cold work tool steels 0.90 0.90 I .-IS I.20
medium-alloy
I .tMl 1.60 0.80
0.50
0.90
0.75
1.75
I.00
0 25
cold Hark tool steels I .OO I.25 1.00 0.70 2.25 0.55 0.50 1.35
T-30102 T30103 T3Olo-1 T30106 T30 IO7 T30108 no109 T30110
bighchromium
5.00 5.00 I.00 lo0 _ _ 3 .2 > 5.00 S.00
2 00 2.00
1.80
I SKI
-1:;5
I OO(Cl I .29
I Ml
I.25
I On I .OO I.00 I.25 I .OO I.25 I .-lu I .SO
I50 1.80
cold work steels 11.00 l-7.00 1200 I2.00 I’.00
1.50 2.3 2.3 I so 2.35
special-purpose
L6
Cr
o.;o
0.50 0.50 0.55 0.45 0.50
T30402 l-30403 T3o-Io-1 T3040.5 T30407
Low-alloy, I2
types of tool steels
tool steels
T3lSOl T3 1502 T31506 l-3 I so7
01 02 06(b) 07
Si
0.60-I .-m(S) 0.60-1.10(a) I.10
T-II901 T-l I902 T4 I905 T-II906 T4 I907
SI S2 S5 S6 Sl
hln
of principal
tool steels T72301 l-7230’ l-72305
Shock-resisting
compositions
I00
I Ml
-1.00
1.00 I SKI I.00
3.00
tool steels
T6 I202 T61206
O.SO-l.IO(ar 0.70
I 00 0 75
TS I602 T5 1603 TSl6O-l T5 160s TSl606 TSl620 TSl621
0.07 0.10 0.07 0.10 0.10 0.35 0.30
2 00 060 5 00 ‘5 -’ -_ I SO I .70
0.20 O.GiCl
I .so
0.20
0.50 1.2.5
Mold steels P2 P3 P-l PS P6 P20 El
Chromium
0.75 3.50 O.-l0 itlo
I.lO~Al)
hot work tool steels T?0810 T208ll I’20812 l-20813 l-208 I J T20819
HI0 HII HI2 HI3 HI1 HI9
0.40 0.3S 0.35 0.35 0.40 0.40
3.15 S.00 s.00 S.00 5 00 l.2.s
0.35 0.35 0.30 0.45 0.25 0.50
0.60
0.40 040 O-IO 1.00
I .so
2.00
;:im 4.25
3.50 2.00 12.00 3.00 4.00 4.00
I:&
9.00 II.00 I2.00 I S.00 IS.00 18.00
1.00
200
6.00
2 50 I .SO I so I so 1.25
Tungsten hot work tool steels T-2081 I I20822 l-20823 TzO82-l l-20825 r-0826
HZI H22 H23 HZ-l H?S H26
hlolybdenum H-U
lbgsten TI IT!
(81 A\ailsble
hot work tool steel T208-l’
high-speed tool steels TllOOl Tl2002
with different
-1.00 1.00 Ironllnu~dI
0.751a1 0.80
carbon conlen&.
I b, Contains graphw.
(L‘J Opional
I .Ou 2.00
18.00 18.00
5.00
Tool Steels / 515
Classification
and approximate
AISI
UNS No.
Tl2OOS Tl2006
TX TIS
TlNQ8 T170lS
hfolybdeoum hll hl2 h13. class I M3. class 2 hll h16 h17 hfl0 hl30 hl33 h13-I h135 M36
Ultrahard h1-l I
M1? hl-13 MU
hi&speed
of principal
types of tool steels Identifying
C
Rmgsleo high-speed tool steels Tl2004 l-4 TS T6
compositions hln
Si
Cr
elements, % v w
-1.00 -I.00 -I.50 -I.00 1.00
1.00 2.00 1.50 2.00 5.00
4.00 4.00 1.00 -I.00 4.00 -I.00 4.00 1.00 -l.oCJ -loo 4.00 3.75-1.50 4.oCJ
1.00 2.00 2.10 3.00 4.00 200 2.00 2.00 I.25 I.15 2.00 1.75-1.20 2.00
4.3 3.75 3.75 1.25 1.00 3.75 3.50.4.00 3 75-1 so 3 504.30 3 50-400
2.00 I.15 I.60 2.00 3.20 I.25 2.75-3.x 0.80-I .3 I .65-2.2.5 I .80-2.00
0.75 0.80 0.80 0.75
I.50
(continued) hlo
18.00
co
Ni
5.00 8.00
18.00 ‘0.00 14.00 I ?.(JO
12.00 5.ocl 5.00
.
tool steels
Tll301 Tll30’ Tll313 TI 1323 Tll301 Tll306 TI 1307 Tll3lO Tll3.30
Tll333
0.8Ois) 0.85-1.00(a) I.05 1.20 1.30 0.80 I .OO 0.85-l w(a) 0.80
0.90
TI 13.33 TI I.335 TI 1336
high-speed bol steels Tll311 Tll3-U TI 1313
hl-16 M47 hl-48 hlS0
Tll3-U Tll34.6 Tll347 TI 13-18 TI I350
hlS2 h162
TI 1352 TI 1362
0.90 0.X2-0.88 0 80
0. I s:o.10
0.20-0.4s
I.10 I.10 1.20
I.15 I J.5 I IO I .-l1- I .52
0.15-0.40
0 78-0.8X 0.85-0.95 1.25-1.3s
0 IS-O.45 0. IS-O.-IS 0.15-0.40
0.15-010 0.20-0.60 0.20-0.60 0. I s-o.40
I.50 6.00 6.00 6.00 5.50 -1.00 I .75
1.00 I so 2.00 9.50-6.75 6.00
6.75 I .so 2.75 5.25 2.00 I.50 9 50. IO.50 0.75-I so 5.75-6.50
8.00 5.00 5.00 s.ocl -1.50 5.00 8.75 x.00 8.00 9.50 8.w 5.00
3.75 9.50 8.00 6.25 8.25 9.50 0 IS -0.40 3.90-4.7s 4.00-4.90 lO.W- I I .oo
12.00
5.00 8.00 8.00 1.50-5.50 8.00
0.30 max
5.00 8.ocl 8.25 12.00 8.2s 5.00 8.00-10.00
0.30“’ rllax 0.30 max 0.30 max 0.30 max
~a) Available with different cabon sontents. (b) Contains graphite. tc) Optional
applications tools.
requiring
extreme
toughness
including
punches and heading
Mold %%!I% Tool steels listed under the symbol P are generalI> intended for mold applications. Types P2 and P6 are low in carbon content and are usually supplied at low hardness to facilitate cold hubbing of the impressions. They are then carburized to develop the required surface properties for injection and compression molds for plastics. Types P20 and P2l are usually supplied in the pre-hardened condition. to allow the cavity to be machined and the mold to be placed directly in service. These grades may be used for plastic molds. zinc die casting dies. and holder blocks. Hot Work Steels. Hot work steels are divided into three groups: chromium. tungsten, and molybdenum. Of the grades of chromium hot work steels listed in the Table. grades HI I and H I3 are the most widelq used. Both of them are also used for nontooling applications, notably in the aerospace industry. Principal tooling applications include forging dies and die inserts. blades for hot shearing, and dies for die casting of aluminum alloys. Grades HI1 and HI9 are sometimes used for applications where greater heat resistance IS required. Including dies for die casting brass. The tungsten types are intended for hot work applications bhcre resistance to the softening effect of elevated temperature is of greatest importance. and a lesser degree of toughness can be tolerated. Of the grades listed in the Table, H2 I and H26 are most often used. Die casting dies for the copper-base alloys and hot extrusion tools are typical examples of their applications.
The molybdenum types are low-carbon modifications of molybdenum high-speed steels. They offer excellent resistance to the softening effect of elevated temperature. but similar to the tungsten types. should be restricted to those applications where less ductility is acceptable. These steels are not readily available except on a mill delivery basis. High-Speed Steels. The high-speed steels are divided into three groups: (a) those bearing the symbol T where tungsten is the major alloying element; (b) those bearing the symbol M indicating that molybdenum is the principal alloying element: (c) a group of more highly alloyed steels that are capable of attaining unusually high hardness values. TI was one of the original high-speed steels. although all tungsten grades are used to a limited extent because of the cost and questionable availability of tungsten. Of the T steels, general purpose TI and high-vanadium-cobalt Tl5 are most commonly used. Tl5 is used forcutting tools that are exposed to extremely rigorous heat or abrasion in service. The hl tool steels generally are considered to have molybdenum as the principal alloying element. although several contain an equal or a slightly greater amount of such elements as tungsten or cobalt. Types with higher carbon and vanadium contents offer improved abrasion resistance. but machinability and grindability may be adversely affected. The series beginning with M-l I is characterized by the capabilib of attaining exceptionally high hardness in heat treatment. reaching hardnesses as high as Rockwell C. In addition to being used for cutting tools. some of the M high-speed steels are successfull>. used for such cold work applications as cold header die inserts. thread rollmg dies, and blanking dies. For such applications, the high-speed steels are hardened from a lower temperature than that used for cutting tools to increase toughness.
Water-Hardening
Tool Steels
(W Series) Introduction The v,ater-hardening tool steels considered here (W I. H’2. and WS) are essentially carbon steels and are among the least expensive tool steels As a class, these steels are relatively low in hardenabilitj. although they arc arbitrarily classified and available as shallo\\-hardening. medium-hardening. and deep-hardening types. Except in very small sizes. LV steels u’ill harden with a hard case and a soft core. Their IOU hardenabilitl is frequently an advantage. because it allows tough core properties in combination with high surface hardness. They are available in a range of carbon content. allowing for maximum tou@u~ess with loser carbon content or maximum wear resistance with higher carbon content, depending on planned use. Water-hardening tool steels are most commonly hardened by qusnching in water or brine. However. thin sections may be hardened suitably bj oil quenching with less distortion and danger of cracking than if the sections were quenched in water or brine. In general, these steels are not normalized except after forging or before reheating treatment. for refining the grain and producing a more uniform structure. Parts should be protected against decarbunzation during au cooling. These steels are received from the supplier in the annealed condition. and further annealing is generally not required. Stress relieving prior to
Water-Hardening mum Hardness.
Tool Steels: Oil quenched
Section to 60 HRC
Thickness
vs Mini-
hardening is sometimes emplqcd to minimize distortion and cracking, particularly when tools are cornpIe\ or have been severely cold marked Similarly, prrheatinp prior to austenitizinp is unusual except for very large tools or those with intricate crosb sections. To produce maximum depth of hardness in Nater-hardening tool steels. it is essential that the) be quenched as rapidly as possible. In most instances. iiater or a brins solution consisting of IO wt C NaCl in water is used. For an Eden fa>ter quench. an Iced brine solution may be used. These steels should be tempered immediately atier hardening, preferably before the? feach room temperature. Salt bnthh. oil baths, and air furnaces are all satlstactoc; for tempenng. However. working temperatures for both oil and salt are lirmted: the minimum for salt is approximately I65 “C (330 “F), and the maximum for oil is approximately 205 “C (100 “F). Tools should be placed in a \\arm furnace of Y-l to I20 “C (200 to 250 “F) and then brought to the tempering temperature I$ ith the furnace. The resistance to fracture by impact initially increases u ith tempering temperature to approximately I80 ‘C i35S “F) but falls off rapidly to a minimum at approximately 260 “C (500 “F). Double tempering may be requued to temper any martensite that may have formed from retained nustenite dunng cooling in the first tempering c~cls.
Nater-Hardening sracking
Tool Steels:
Fracture
Grain Size vs Quench
Tool Steels / 517
Water-Hardening Tool Steels: Hardness vs Tempering Temperature. Specimens held for 1 h at the tempering temperature in a recirculating-air furnace. Cooled in air to room temperature. Data represent twenty 25 mm (1 in.) diam specimens for each steel. Each quenched from temperatures indicated. (a) Shallow hardening: 0.90 to 1 .OOC, 0.18 to 0.22 Mn, 0.20 to 0.22 Si, 0.18 to 0.22 V. (b) Medium hardening: 0.90 to 1 .OO C, 0.25 Mn, 0.25 Si. no alloying elements. (c) Deep hardening; 0.90 to 1 .OOC, 0.30 to 0.35 Mn, 0.20 to 0.25 Si. 0.23 to 0.27 Cr
Water-Hardening Tool Steels: Hardness vs Tempering Temperature. 1% C. Size: 25 mm (1 in.) round by 51 mm (2 in.) long. Valid fortempering times from l/2 to 2 h. Quench temperature: 790 “C (1455 “F) in water. First stage: The decomposition of martensite into low-carbon martensite (about 0.25 C) and epsilon carbide (Fe,&). Epsilon carbide precipitates in the form of film at subgrains, 4 to 8 l.rin. in diam in the martensite. In steels containing more than 0.8 C, the early part of the first stage reaction results in a slight increase in hardness: however, the later portion of this stage is accompanied by a gradual decrease of hardness. Specific volume decreases during this stage. Second stage: Decomposition of retained austenite to bainite takes place over the temperature range from approximately 205 to 315 “C (400 to 600 “F). Hardness continues to decrease during this stage, while specific volume increases. Third stage: Epsilon carbide and low-carbon martensite (0.25 C) react to form ferrite (body-centered cubic) plus cementite. This process is accompanied by softening. Even after the complete disappearance of epsilon carbide, cementite continues to precipitate, depleting the ferritic matrix of carbon and resulting in further softening. Coalescence of cementite particles also contributes to this softening.
518 / Heat Treaters
Guide
Water-Hardening Tool Steels: Manganese Plus Silicon Content vs Penetration of Hardness. 19 mm (3/4 in.) round bars con-
Water-Hardening Tool Steels: Alloy Content vs Hardenability. Effect of total manganese, silicon, chromium, and nickel contents on the hardenability of 1 C steels quenched in brine from 790 “C (1455 “F) for 1 h at temperature. Hardenability expressed as depth of penetration in inches for 25 mm (1 in.) round bars
Water-Hardening Tool Steels: Effect of 1% Additions Alloying Elements on Hardenability
of
Relative hardenability factors for alloy additions to 1% carbon tool steel, austenitized at normal temperatures with incomplete carbide solution. Treatment: 40 min at 870 “C (1600 “F) oil quench; 12 min at 790 “C (1450 “F), agitated brine quench (H = 5.0)
Steel I% carbon (base ) I% silicon IQ manganese I9 tungsten I%~chromium I90 molybdenum I Sr, niche1
Penetration in I%-in. round, ‘/aJ in. 5 1/2 I8 I6 4 ‘/: I6 22 IO
Multiplying
factor Corresponding D,
forl%
addition
Fracture grain size 9
0.67 I.16 1.09 0.62
1.30 2.17 0.93
9 8v~ 9%
1.09 I .-Cl 0.89
I .63 2.16 I .33
IO 93/, 9v,
taining 1 to 1.10 C, 0.02 to 0.04 Ni, 0.010 to 0.015 S, 0.012 to 3.016 P. Quenched in brine from 790 “C (1455 “F). Source: Teledyne VASCO
Water-Hardening Tool Steels: Composition Calculated Hardenability
vs Critical diameter for brine quench,
iIl.(E =-SO) Heat No. lb 7 i -I 5 6 7 8 9 IQ II I2
C
hln
1.02 1.03 I .07 I II7 I .oo I.09 104 I.00 0.97 0.99 0.98 0.9-l
009 0’8 0.15 0.3-l 0.2-l 0.26 0.29 031 0.46 0.36 o.so 0.45
13) 0.03pi vanadium
Composition, ?c Si Cr 0.03 0.1s 0.09 0.22 0.17 0.26 0.16 0.28 0.29 0.31 0.37 0.36
0.0s 0.0-l 0.05 0.10 0.09 0. I7 0.15 0 13 0 I7 0.15 0.23 0.2 I
Ni 0.02 0.02
0.10 0.03 0 07 0.20 0.1-l 0.07 0.05 0. I 7 0.12 0.16
MO
0.03 nil nil nil 0.0 I nil 0.03 0.03 nil 0.03 0.03 nil
Calculated 0.1s 0.35 0.20 0.15 0.15 O.-IS 0.50 0.60 0.80 0.75 0.90 I .o
Observed wpmx
518 / Heat Treaters
Guide
WI Chemical COmpOSitiOn. AISI: Nominal. 0.60 to 1.40 C, 1.50 Cr. 2.50 W. AISI/UNS (T72301): 0.70 to 1.50 C*, 0.10 to 0.40 Mn, 0.10 to 0.40 Si, 0.20 Ni max. 0.15 Cr max, 0.10 MO max, 0.10 V max, 0.50 W max * specified carbon ranges are designated by suffvt numbers Similar
Steels (U.S. and/or
Foreign).
ASTM ~686 (w-l); SAE J437 (W108), (W109), (WllO), (W112), 5438 (W108), (W109), (WllO), (W112); (Ger.) DIN 1.1525, 1.1545, 1.1625, 1.1654, 1.1663, 1.1673, 1.1744, 1.1750, 1.1820, 1.1830; (Fr.) AFNOR A35-590 1102 Y(1) 105, A35-590 1103 Y (1) 90, A35-590 1104 Y (1) 80, A35-590 1105 Y (1) 70,
A35-590 1200 Y (2) 140, A35-590 1201 Y (2) 120, A36-596 Y75, A35-596 Y90; (Jap.) JIS G4401 SK 1, G4401 SK 2, G4401 SK 3, G4401 SK 4, G4401 SK 5, G4401 SK 6, G4401 SK 7, G4401 SKC 3; (U.K.) B.S. 4659 (SA Wl), 4559 BWlA, 4659 BWlB, 4659 BWlC
Characteristics.
Capable of hardening to high surface hardness and soft core which is useful in some shock applications. Low cost tool steels with fair to good wear resistance as carbon content increases. Water quenched with poor dimensional stability. Use limited to fairly uniform sections with minimum amount of stress raisers or quench cracking can occur
Tool Steels / 519 Forging. Start forging at 980 to 1065 “C (1795 to 1950 “F). Use upper temperature of range for 0.60 to 1.25 C, and lower temperature of range for 1.25 to 1.50 C. Do not forge below 815 “C (1500 “F)
Recommended
Heat Treating
Practice
Normalizing. For 0.60 to 0.75 C, heat to 815 “C (1500 “F); for 0.75 to 0.90 C, 790 “C (1455 “F); for 0.90 to 1.10 C, 870 “C (1600 “F); for 1.10 to 1.50 C, 870 to 925 “C (1600 to 1695 “F). After uniform through heating, holding time varies from approximately 15 min for small sections to approximately 1 h for large sections. Work is cooled from temperature in still air Annealing.
For 0.60 to 0.90 C, heat to 740 to 760 “C (1365 to 1400 “F); for 0.90 to 1.50 C, heat to 760 to 790 “C (1400 to 1455 “F). Use lower limit for small sections and upper limit for large sections. Holding time varies. Sections up to 25 mm (1 in.) require at least 20 mitt; 203 mm (8 in.) sections require 2 l/z h. For pack annealing, hold for 1 h per inch of cross section. Cool to 540 “C (1000 OF) at a rate not to exceed 28 “C (50 “F) per h, after which controlled cooling is not necessary. Hardness after annealing, 156 to 201 HB
Relieving. Optional. Heat to 650 to 675 “C (1200 to 1245 “F) and hold for 1 h per inch of cross section (minimum of 1 h). Cool in air
Stress
for 10 min for small sections to 30 min for large sections. Quench in agitated water or brine. A spray directed into a recessed configuration, such as a die cavity, or at the working end of a punch is often used to obtain maximum hardness and residual compressive stress in a desired area. Approximate quenched hardness, 65 to 68 HRC
Tempering.
Temper immediately after hardening, preferably before tool reaches room temperature; approximately 50 “C (120 “F) is optimum. Allowing quenched tools to stand at room temperature or placing them in a cold furnace will lead to cracking. Therefore, place tools in a warm furnace at 94 to 120 “C (200 to 250 “F) immediately after quenching and bring to tempering temperature with the furnace. Except for large pieces. work will heat at approximately the same rate as the furnace. Temper at temperatures not lower than 175 “C (345 “F) and up to approximately 345 “C (655 OF). One hour at temperature is usually adequate; additional soaking time will further lower hardness. A double temper may be required. The low temperatures used in tempering eliminate the need for atmosnhere 1 control. Approximate tempered hardness, 50 to 64 HRC
Recommended l l l
Hardening.
Preheating is necessary only for intricate sections or large sections where temperatures would differ appreciably from surface to center. Heat slowly to 760 to 845 “C (1400 to 1555 “F), using the upper end of the temperature range for low carbon contents and lower end of the temperature range for high carbon contents. Using temperatures at the upper end of the temperature range will increase hardenability. Austenitized
Wl : Isothermal Transformation and Steel Institute
Diagram. Source: British Iron
l l l l l l
Processing
Sequence
Normalize Rough machine Stress relieve (optional) Finish machine Preheat Austenitize Quench Temper (double temper, optional) Final grind to size
Wl: Hardness vs Tempering Steel
Temperature.
Source:
British
520 / Heat Treaters
Wl: Isothermal Si. Austenitized
Guide
Transformation Diagram. at 790 “C (1455 “F)
Composition:
1.14 C. 0.22 Mn, 0.61
Wl : Hardness vs Tempering Temperature. Composition: 0.98 C, 0.30 Mn, 0.30 Si. Specimens hardened by brine quenching after 1 h at 870 “C (1600 “F) and cooling to -71 “C (-95 “F) in dry ice and alcohol
Wl: Case and Core Hardness. Composition: 1.06 C, 0.36 Mn, 0.27 Si, 0.01 S, 0.015 P, 0.05 Cr. 19 mm (?/4 in.) round bar, brine quenched from 815 “C (1500 “F). Pretreated by oil quenching after 40 min at 870 “C (1600 “F). Source: Teledyne VASCO
Wl : Length Changes. Contains 1.07 C. Tempering time is considered to begin 1 ‘12 h after hardening
Tool Steels / 521
Wl: Microstructures.
(a) 4% picral, 1000x. 1 .lO C. 0.30 Mn. Normalized by austenitizing at 925 “C (1695 “F) and air cooling. 227 HB. Lamellar pearlite with thin envelopes of cementite at grain boundaries. (b) 3% nital, 1000x. 0.94 C. 0.21 Mn. Austenitized at 790 “C (1455 OF) and quenched in brine (not tempered). 65 HRC. Largely untempered martensite with some undissolved carbide particles. (c) 3% nital, 1000x. Same steel and heat treatment as (b), after tempering at 165 “C (330 “F). 64 HRC. Tempered martensite (dark background) with a few spheroidal particles of carbide (white dots). (d) 3% nital, 1000x. Same steel and heat treatment as (b), after tempering at 260 “C (500 OF). 58 HRC. Gray constituent is tempered martensite. Its appearance has changed from (c). White spots are carbide particles. (e) 3% nital, 1000x. Same steel as (b), austenitized at 760 “C (1400 “F), Quenched in brine, tempered at 160 “C (320 “F). 44 HRC. Mixture of peariite (dark), tempered martensite (gray), and ferrite indicates underheating. (f) 3% nital. 1000x. Same steel as (b), austenitized at 855 “C (1570 “F), quenched in brine, tempered at 160 “C (320 “F). Coarse-grained tempered martensite and retained austenite (white), the result of overheating. (g) 2% nital. 1000x. Case of hardened Wl. 1.05 C, 0.31 Mn. Austenitized at 800 “C (1475 “F), water quenched, and tempered at 175 “C (345°F). 64 HRC. Spheroidal cementite in tempered martensite. (h) 2?0 nltal, 1000x. Transition zone between case and core of hardened Wl, heat treated as for(g). 47 HRC. Fine spheroidal cementite in a matrix of martensite (light) and pearlite (dark). (j) 2% nital, 1000x. Core of hardened Wl, heat treated as for (g). 36 HRC. Fine spheroidal particles of cementite in a matrix of fine pearlite (dark-etching constituent)
522 / Heat Treaters
Guide
w2 Chemical AISIjUNS
Composition. AISI: Nominal. 0.60 to I.-IO C, 0.25 V. (T72302): 0.85 to 1.50 *C. 0. IO to 0.40 Mn, 0. IO to 0.30 Si.
StreSS RdieVing. Optional. Heat to 650 to 675 “C (I200 to 12-U “F) and hold for I h per inch of cross section (minimum of I h). Cool in air
0.20 Ni max. 0. IS Cr max. 0. IO MO max, 0. I5 to 0.35 V. 0. IS W max * specified
carbon ranges are designated
hy suffix
numbers
Similar Steels (U.S. and/or Foreign). ASTM ~686 (w-2): FED QQ-T-580 (W-2); SAE J-l37 (W209). iW2lO). 5138 (W209). (W210): (Ger.) Dm 1.1645. 1.2206. 1.2833: (Fr.) AFNOR A3S-590 II61 Y I20 V. A35590 II62 Y IO5 V. A35-590 II63 Y 90 V. A35-590 I I@ Y 75 V. A3S-590 2130 Y 100 C 2, A35590 1232 Y I05 C; tJap.1 JIS G-l-IO-l SKS 13,G-WO-ISKS44:(U.K.)B.S.4659 BW2;(Swed.)SStlJSA WZA).(USA W2B). (LISA W2C) Characteristics. Capable of hardening to high surface hardness and soft core which is useful in some shock applications. Low cost tool steels with fair to good wear resistance as carbon content increases. Water quenched with poor dimensional stability. Use limited to fairly uniform sections with minimum amount of stress raisers or quench cracking can occur Forging. Start forging at 980 to 1065 “C (I795 to 1950 OF). Use upper temperature of range for 0.60 to I .25 C. and loner temperature of range for I .25 to I SO C. Do not forge below 8 IS “C ( I500 “F)
Recommended
Heat Treating
Practice
Normalizing. For 0.60 to 0.75 C. heat to 815 “C ( I500 OF); for 0.7s to 0.90 C, 790 “C (l-IS5 OF); for 0.90 to I. IO C, 870 “C (I600 OF): for I IO to I.50 C. 870 to 925 “C (1600 to I695 “F). After uniform through heating, holding time varies from approximateI> I5 min for small sections to approximately I h for large sections. Work is cooled from temperature in still air
Annealing.
For 0.60 to 0.90 C, heat to 710 to 760 “C ( I360 to 1400 “F); for 0.90 to I SO C, heat to 760 to 790 “C (l-100 to lk5S OF). Use lower limit for small sections and upper limit for large sections. Holding time varies. Sections up to 25 mm ( I in.) require at least 20 min; 203 mm (8 in.) sections require 2 t/z h. For pack annealing, hold for I h per inch of cross section. Cool to 510 “C (1000 “F) at a rate not to exceed 28 “C (SO “F) per h. after which controlled cooling is not necessary. Hardness after annealing. IS6 to 201 HB
W2: Effect of Furnace Atmosphere on Surface Carbon Content. Specimens heated at 790 “C (1455 “F) for 1 h, quenched in brine, annealed in lead at 705 “C (1300 0.127 mm (0.005 in.) cuts for analysis
“F), and machined
in
Hardening. Preheating is necessary onI> for intricate sections or large sections where temperatures would differ appreciably from surface to center. Heat slowly to 760 to 845 “C ( I-!00 to I555 “F). using the upper end of the temperature range for low carbon contents and lower end of the temperature range for high carbon contents. Using temperatures at the upper end of the temperature range will increase hardenability. Austenitized for IO min for small sections to 30 min for large sections. Quench in agitated water or hrine. A spray; directed into a recessed configuration. such as a die cavity or at the uorktng end of a punch. is often used to obtain maximum hardness and residual compressive stress in a desired area. Approximate quenched hardness. 65 to 68 HRC Tempering.
Temper immediately after hardening, preferably hefore tool reaches room temperature: approximately 50 “C (120 “F) is optimum. Allowing quenched tools to stand at room temperature or placing them in a cold furnace will lead to cracking. Therefore, place tools in a warm furnace at 91 to I20 “C (200 to 250 “F) immediately after quenching and bring to tempering temperature with the furnace. Except for large pieces. work will heat at approximately the same rate as the furnace. Temper at temperatures not lower than I75 ‘C (315 “F) and up to approximately 345 “C (655 “F). One hour at temperature is usually adequate; additional soaking time will further lower hardness. A double temper may be required. The low temperatures used in tempering eliminate the need for atmosphere control. Approximate tempered hardness. SO to 61 HRC
Recommended l l l l l l l l l
Processing
Sequence
Normalize Rough machine Stress relieve (optional) Finish machine Preheat Austenitize Quench Temper tdouhle temper. optional) Final grind to size
W2: Hardness vs Tempering Temperature. Tempering band for W2 and W5, containing 0.90 to 1.10 C. Austenitized at 760 “C (1400 “F) and 840 “C (1545 “F). Shaded portion indicates opti-
mum tempering
range. Source: British Steel
Tool Steels / 523
W5 Composition. AISI: AlSI/UNS (T72305): 1.05LOI.15 *C. Chemical
Nominal. 1.10 C, 0.50 Cr. 0. IO to 0.40 Mn. 0.10 to 0.40 Si. 0.20 Ni max. 0.40 to 0.60 Cr. 0. IO hfo max. 0. IO V max. 0. I5 W max * specitied carbon ranges are designated by sufftx numbers
Similar
Steels (U.S. and/or
Foreign).
ASTM
A686 (W-S)
Characteristics. Capable of hardening to high surface hardness and soft core which is useful in some shock applicattons. Low cost tool steels with fair to good wear resistance as carbon content tncreases. Water quenched with poor dimensional stability. Use limited to fairly uniform sections with minimum amount of stress raisers or quench cracking can occur Forging.
Start forging at 980 to 1065 “C (1795 to 1950 “F). Use upper temperature of range for 0.60 to I.25 C, and lower temperature of range for I .25 to 1.50 C. Do not forge below 8 IS “C ( I500 “F)
Recommended
Heat Treating
Practice
Normalizing.
For 0.60 to 0.75 C. heat to 8 IS ‘C ( IS00 “F): for 0.75 to “F): for 0.90 to I. IO C. 870 “C ( 1600 “F); for I. IO to I SO C, 870 to 925 “C (I 600 to 1695 “Fj. After uniform through heating. holding time varies from approximately IS min for small sections to approximately I h for large sections. Work is cooled from temperature in still air
0.90C. 790"C (135.5
Annealing.
For 0.60 to 0.90 C. heat to 730 to 760 ‘C (I 365 to 1300 “Fj: for 0.90 to I SO C, heat to 760 to 790 “C (1300 to 1455 “F). Use lower limit for small sections and upper limit for large sections. Holding time varies. Sections up to 25 mm (I in.) require at least 20 mitt; 203 mm (8 in.) sections require 2 t/z h. For pack annealing. hold for I h per inch of cross section. Cool to S-10 “C (1000 “Fj at a rate not to exceed 28 “C (SO “F) per h. after which controlled cooling is not necessary. Hardness after annealing. IS6 to 201 HB
Hardening. Preheating is necessary only for intricate sections or large sections where temperatures would differ appreciably from surface to center. Heat slowly to 760 to 815 “C ( 1400 to IS55 “F), using the upper end of the temperature range for low carbon contents and lower end of the temperature range for high carbon contents. Using temperatures at the upper end of the temperature range will increase hardenability. Austenitized for 10 min for small sections to 30 mitt for large sections. Quench in agitated water or brine. A spray directed into a recessed configuration, such as a die cavity or at the working end of a punch, is often used to obtain maximum hardness and residual compressive stress in a desired area. Approximate quenched hardness, 65 to 68 HRC Tempering.
Temper immediately after hardening, preferably before tool reaches room temperature: approximately 50 “C (120 “F’) is optimum. Allowing quenched tools to stand at room temperature or placing them in a cold furnace will lead to cracking. Therefore, place tools in a warm furnace at 94 to I20 “C (200 to 250 “F) immediately after quenching and bring to tempering temperature with the furnace. Except for large pieces, work will heat at approximately the same rate as the furnace. Temper at temperatures not lower than I75 “C (3-U “F) and up to approximately 345 ‘C (655 “F). One hour at temperature is usually adequate; additional soaking time will further lower hardness. A double temper may be required. The low temperatures used in tempering eliminate the need for atmosphere control. Approxtmate tempered hardness, 50 to 64 HRC
Recommended l l l l l l l
Stress RdieViIIg. Optional. Heat to 650 to 675 “C ( I200 to 12-0 “Fj and hold for I h per inch of cross section (minimum of I h). Cool in air
l l
Processing
Normalize Rough machine Stress relieve (optionalj Finish machine Preheat Austenitize Quench Temper (double temper, optional) Final grind to size
Sequence
Shock-Resisting
Tool Steels
(S Series) introduction The prmcipal steels in this group tSI. SZ. SS. S6. and S7) may he ohtained with several lariations in composition for specitic applications. These variations may require modilications in heat treating which ma! be obtained from the steel supplier or detemined h) actual tests for rhose steels not described below. All of these steels contain from 0.40 IO 0.605 carbon to ensure a sufficiently high hardness without impairing impact strength and shock resistance. The S steels are not normalized and. when annealed, rhe recommended annealing temperature must not be exceeded. This is especialI> important when annealing those sreels \rith high silicon content. The high-sihcon steels are susceptible to graphhization and decnrburization. wth graphitization occurring at excessively high annealing temperatures. Like all tool steels, S senes steels must be protected ngalnst decarhurization, The silicon steels should not be soaked at temperature. Except for extremely intricate tools of \cidslj varying section thickness. stress relieving hefore hardening is seldom required. IVhen stress
relic\ mp is employed. the steel should be furnace cooled to approximalel) 5 IO ‘C (950 ‘FI and then cooled in air. Preheating prior 10 austenirizing is nor mandatory, hut it can he desirable for large tools. to minimize distoruon. to shorten time at austenitizing ~emperaturs. and to speed up production. For austenitizing temperatures below 870 ‘C (I600 “FI. a slighd! oxidizing atmosphere is best. hut a reducing atmosphere IS requrred for temperatures above 870 “C ( 1600 “F). Atmosphere furnaces. neutral salr baths. and packing media withoul contaminants are widely used for austeniuzing. Types S2 and S5 should be quenched nlmosl as soon as they reach the nusterutizing tempemture: ho\\ever. SI ‘and S7. which have the highest hardsnahilit! of these steels. are held at lemperatures for IS to 45 mm before hemp quenched. All of the shock-resisting steels should be tempered immediately after quenching to pre\ ent cracking. Type S I is often carburized or carhonitrided to increase surface hardness and wear resistance uithout detracting from impact suength to an! extent.
Sl Chemical
COITIpOSitiOn. AISI: Nominal. 0.50 C. 1.50 Cr. 2.50 IV. AISI/UNS (T41901): 0.40 to 0.55 C. 0.10 toO.-lO Mn. 0. IS to 1.20 Si. 0.30
Ni max. 1.00 to 1.8OCr. 0.50 MO mas, 0.15 to 0.30 V, I.50 to 3.00 b
Similar
Steels (U.S. and/or
Foreign).
ASTM A68 I (S-I ); FED QQ-T-570(S-I ): SAE J138(S-I); (Gsr.) DIN 1.2542. 1.2550; (Fr.) .AFNOR 55 WC 20. AX-590 2341 55 WC 20: (Ital.) L)Nl 158 W Cr 9 KC! (Jap.) JIS G-l-IO-l SKS 41; (Swed.) SS 2710: (U.K.) B.S. -I659 BSI
Characteristics.
Availahlc in a variety of chemical compositions. Varymg carbon, silicon, tungsten. and chromium contents affect response to heat treatment. hlodilications in heat treatment should he ohtamed from steel supplier. if not covered m the follo\~ing data. Higher silicon contents promote graphitization at excessively high annealing temperatures
Forging. Start forgmp at IO IO to I I20 “C ( I850 to 2050 “F). Do not forge below 870 “C ( I600 “F)
Recommended Normalizing.
Heat Treating
Practice
Do not nomralize
Stress Relieving. Optional. Heat to 650 to 675 “C (1200 to 12-U “FJ and hold for I h per inch of cross sectton (mrmmum of I h). Cool tn air
Hardening. Heat slowly. Preheat at 650 “C ( 1200 “F). Austenitize at 900 to 955 “C ( 1650 to I750 “F). hold for IS to 35 min. then quench in oil. As-quenched hardness. 57 to 59 HRC Stabilizing. Optional. For intricate shapes, stress relieve temper at IS0 to 160 “C (300 to 320 “F) brietly. Refrigerate at -100 to -195 “C (-150 to -320 “F). Temper immediately after part reaches room temperature Tempering.
To pre\ent cracking. temper within 30 min if from 900 “C ( 1650 ‘F). IS min if quenched from 955 “C (I750 may vary wth size and shape. Temper at 205 to 650 ‘C (100 to Approximate tempered hardness as it corresponds to tempering ture. 58 to 10 HRC
Recommended l l l
Annealing. Heat to 790 to 830 “C ( I-!55 to 1525 “F). Use lo\rer limit for small sections and upper limit for large secttons. Holding time \aries from approximately I h for light sections and small furnace charges. to approxtmately 3 h for heavy sections and large charges. Cool at a rate not to escssd 22 “C (40 “F) per h. hlaximum rate not critical after cooling to approxtmately 5 IO “C (950 “F). Ty picaJ annealed hardness. I83 to 235 HB
l l l l l l
Processing
Rough machine Stress relieve (optional) Finish machine Preheat .Austenitize Quench Stabilize (optional) Temper Final grind to size
Sequence
quenched “F). Time 1200 “F). tempera-
Tool Steels
Sl: Isothermal Transformation Diagram. Containing 0.50 C. 0.25 Mn, 0.75 Si. 1.25 Cr, 0.20 V, 2.50 W. Austenitized at 925 “C (1695 “F). Source: Uddeholm
Sl : End-Quench Hardenability. 1: Sl contaimng 0.53 C, 0.38 Mn, 0.26 Si, 1.42 Cr, 2.13 W. 2: Sl containing 0.54 C, 0.41 Mn. 1.02 Si, 1.40 Cr, 2.20 W. 3: Sl containing 0.51 C, 0.39 Mn, 0.26 Si, 1.43 Cr. 0.30 V, 2.15 W, 0.51 MO. 4: Sl containing 0.52 C, 0.42 Mn, 1.04 Si, 1.46 Cr, 0.32 V, 2.14 W, 0.53 MO. All austenitized at 950 “C (1740 “F)
/ 525
Sl : Hardness vs Austenitizing Temperature. 0: 0.45 C. 1.50 Cr, 2.41 W, quenched in water; specimen, 25 mm (1 in.) by 127 mm (5 in.) 0: 0.55 C, 1.35 Cr, 0.25 V, 2.00 W. quenched in oil. & 0.43 C, 1.30 Cr. 0.25 V. 2.00 W, quenched in oil; specimen, 22.2 mm (?‘a in.) diam by 76 mm (3 in.) A: 0.52 C, 0.85 Si, 1.30 Cr, 0.25 V, 2.25 W. Quenched in oil: specimen, 22.2 mm (7/~ in.) diam by 63.5 mm (2 ‘12 in.) q : 0.45 C, 1.50 Cr, 2.41 W. Quenched in oil; 25 mm (1 in.) diam by 127 mm (5 in.). Sources: Allegheny Ludlum, Bethlehem Steel, Latrobe Steel
Sl: Cross-Sectional Hardness. Sl containing 0.50% and O.6O?/0C, austenitized at 925 “C (1695 OF) and quenched in oil. Source: ColumbiaTool Steel
526 / Heat Treaters
Guide
Sl: Hardness vs Tempering Temperature. Sl austenitized at 955 “C (1750 “F) and quenched in oil. As-quenched hardness, 59 HRC. Source: Universal-Cyclops
Sl: Hardness vs Tempering Temperature. shows optimum range for best combination toughness
Shaded portion of hardness and
Sl: Microstructures. (a) 3% nital, 1000x. As received (mill annealed). Hardness. 183 HB. Dispersion of fine spheroidal particles of carbide (dark spots) in matrix of ferrite. (b) Nital, 1000x. Normalized by austenitizing at 980 “C (1795 “F) for 1 h and air cooling. Carbide particles are dispersed in martensite, probably some bainite, and retained austenite. (c) 3% nital, 1000x. Austenitized at 815 “C (1500 “F) and oil quenched. Dispersion of fine carbide particles in the ferrite matrix indicates underheating during austenitizing. Some untempered martensite is present. (d) 3% nital, 1000x. Austenitized at 955 “C (1750 “F), oil quenched, tempered at 425 “C (795 “F). Tempered martensite and spheroidal carbide particles. (e) 3% nital. 1000x. Austenitized at 1040 “C (1905 “F). oil quenched, tempered at 220 “C (425 “F). Tempered martensite, coarse because of overheating. (f) 3% nital. 1000x. As cast and tempered at 425 “C (795 “F). Tempered martensite with retained austenite and cellular carbide
Tool Steels
/ 527
Sl: Carburizing Data. Sl containing 0.50 C. 1.65 Cr, 0.25 V, 2.00 W. after pack carburizing. (a) Carbon penetration curves after pack carburizing 1 and 2 h at 900 “C (1650 “F). (b) Effect of tempering temperature on the surface and core hardness of samples oil quenched after pack carburizing 1 h at 900 “C (1650 “F). Samples were 51 by 76 by 31.6 mm (2 by 3 by 1 l/4 in.). Source: Teledyne VASCO
Tool Steels / 527
s2 Chemical Composition. AISI: Nominal. 0.50 C. I .OO Si. 0.50 Mo. AISI/UNS (T41902): 0.40 to 0.55 C. 0.30 to 0.50 hln. 0.90 to I .20 Si, 0.30 Ni max. 0.30 to 0.60 hlo, 0.50 V max
Similar
Steels (U.S. and/or
Foreign).
ASThl A68 I (s-2); FED QQ-T-570 (S-2); SAE J437~S2j. JJ38(S?j; (Ger.j DlN 1.2103; (Fr.) AFNOR A3S-590 2324 Y 45 SCD 6: (U.K.) B.S. -I659 BS?
Characteristics.
Among the most shock resistant of the S series. Has low safety in hardening because cracking in water or brine quenchants is possible. Overheating or oversoaking during austenitizing will lower ductility and promote grain growth. Will decarburize readily if not adequately protected
Forging.
Start forging at 1010 to I I20 “C (I850 to 2050 “F). Do not forge below 870 “C ( I600 “Fj or above I I50 “C (2 IO0 “FL Cool forgings in dry air
Recommended Normalizing. Annealing.
Heat Treating
Practice
Do not normalize
Heat to 760 to 790 “C t 1300 to 14% “Fj. Use lower limit for small sections and upper limit for large sections. Holding time varies from approximately I h for light sections and small furnace charges. to approximately -t h for heavy sections and large charges. Cool at a rate not to exceed 22 ‘C (40 ‘F) per h. Maximum rate not critical after cooling to approximately 5 IO “C (950 “FL Typical annealed hardness. I92 to 2 I7 HB
Stress Relieving. Optional. Heat to 650 to 675 “C (I 200 to 1245 “F) and hold for I h per inch of cross section (minimum of I h). Cool in air
Hardening. Heat slow ly. Preheat at 650 “C ( I200 “F). Austemtize at 845 to 900 “C (IS55 to 16.50 “F), hold for 5 to 20 min. then quench in brine or water. As-quenched hardness. 60 to 62 HRC Stabilizing.
Optional. For intricate shapes. stress relieve temper at I50 to 160 C (300 to 320 “Fj briefly. Refrigerate at -100 to -195 “C (-150 to -320 “Fj. Temper immediately after part reaches room temperature
Tempering.
To prevent cracking, temper within IO min particularly if quenched in brute from 900 “C ( I650 “F). Temper at I75 to 425 “C (345 to 795 “FL Approximate tempered hardness as it corresponds to tempering temperature. 60 to 50 HRC
Recommended l l l l l l l l l
Processing
Rough machine Stress relieve (optionalj Finish machine Preheat Plustenitize Quench Stabilize (optional) Temper Final grind to size
Sequence
528 / Heat Treaters
Guide
S2: Isothermal Transformation
Diagram. S2 containing 0.50 C. 0.35 Mn, 0.018 P, 0.013 S. 1.0 Si, 0.19 Ni, 0.11 Cr. 0.50 MO. Austenitized at 845 “C (1555 “F). Grain size: 8. Source: Carpenter Steel
S2: Jominy Hardenability. Distance from quenched end in 1.6 mm (%ein.) increments. Source: Carpenter Technology Corporation
S2: Hardness vs Tempering Temperature. 0: S2 containing 0.50 C, 1 .lO Si, 0.50 MO, 0.20 V. quenched in water from 860 “C (1580 “F). 0: S2 containing 0.50 C. 1.10 Si, 0.50 MO. 0.20 V, quenched in oil from 900 “C (1650 “F).
SS Chemical Composition. AH: Nommul. 0.55 C. 0.80 hln. 2.00 Si. (T41905): 0.10 to 0.50 C. I.20 to I .50 Mn. ?OfJ WI O.-IO hlo. AISI/UNS 2.50 Si. I.30 IO I.50 Cr. 0.30 to 0.50 hlo. 0.70 to 0.40 V Similar
Steels (U.S. and/or
Foreign).
ASThl ~681 QQ-T-57tJ (S-S); SAE J437(S5). J438tSS~; iGer.) DIN I.233; 1659 BS5
tS-5): FED t1I.K.j B.S.
Forging. forge helo~
Recommended Normalizing. Annealing.
Characteristics.
Rzlubvrly hiph safer! in hardening when quenched in oil. the recommended quenchant. Ovtrrheatirq or o\er\onkinp durmp nustenitizing will lower durabilit> and promote grain growth. U’ill dscarhurize readily if not adequateI) protected. Rradil! nv;~ilahle and among th< less sspenske prad?s
Suart forging 31 IO10 to I IX X70 ‘.C ( I600 ‘Fj
Heat Treating
“‘C ( 1850 to 2050 “FL Do not
Practice
Do not normalize
Heat to 775 IO 800°C I I-125 to l-175 “F). Use loner limit for winll wxtiont and upper limit for large w5ons. Holding rim? wrirs from appro\imat?l> I h fur light malI furnace charges. 10 approximatsI) 1 h for ha\ ! s.xnons und large charges. Cool 31 B rate not to exceed I-i “C 13 ‘F) per h. hlxximum rat? not crlticnl after cooling to approlimareI> 5 IO “C rC)SO‘FL Typical annenkd hardnsss. I92 IO 229 HB
Tool Steels / 529
Sb?SS k?h?Ving. Optional. Heat to 650 to 675 ‘T ( I200 IO I Z-15 ‘-‘FJ and hold for I h per inch of cross section iminimum of I h). Cool in air
Hardening. Heat slou lb. Pwheat a[ 760 ‘C ( 1400 “F). Austenitizs at 870 IO 925 “C ( 1600 10 1695°F). hold for S to 20 nun. then qusnch 111 oil. .Aquachsd hardness. 58 10 61 HRC Stabilizing. Optional. For inksate shapes. aas rclis\r tzmper at IS0 IO IhfJ “C (300 10 310 ‘F) hriefl~. Rrfrigerak at -100 10 -195 ‘;C (-150 10 -320 “FL Temper immediately ufrer part reaches room trmpzraturc Tempering.
To pwen1 crachmg. temper \rithin 30 nun if qurnshed from 870 “C ( I600 “FL IS min if quenched from 925 -C ( I695 “FL Tallper
S5: Isothermal Transformation Si. 0.25 Cr. 0.30 MO. Austenitized
a1 I75 to -ES “C (345 10 79S “FL Approximate tempered corrrsponds to tempering temperature. 60 to SO HRC
Recommended Rough machine l Strc
Sequence
l
Diagram. S5 containing 0.60 C, 0.75 Mn, 1.90 at 900 “C (1650 “F). Source: Crucible Steel Co.
S5: Hardness vs Tempering Temperature. S5 water quenched from 860 “C (1580 “F). As-quenched hardness, 62 HRC. S5 oil quenched from 900 “C (1650 “F). As-quenched hardness, 58 HRC. Source: Unrversal-Cyclops
Processing
hardness as i1
b
S5: Jominy Hardenability. Distance from quenched end in 1.6 mm (l/16in.) increments. Source: Carpenter Technology Corporation
S5: Hardness vs Tempering Temperature. 0: S5 containing 0.50 C, 0.70 Mn, 1.60 Si, 0.40 MO, 0.12 V; quenched in oil from 870 “C (1600 “F). 0: S5 containing 0.60 C, 0.85 Mn, 2.00 Si, 0.25 Cr. 0.25 MO. 0.20 V; quenched in oil from 885 “C (1625 “F). Source: Allegheny Ludlum Industries
530 / Heat Treaters
Guide
S5: Microstructures. (a) Nital, 1000x. Normalized by austenitizing at 925 “C (1695 “F) for 1 h and air cooling. Mixture of martensite and coarse pearfite. (b) 2% nital. 1000x. Austenitized at 900 “C (1650 “F) and oil quenched. Steel not tempered. Fine untempered martensite. See (c). (c) 2% nital, 1000x. Austenitized at 900 “C (1650 “F), oil quenched, and tempered at 400 “C (750 “F). Fine tempered martensite
530 / Heat Treaters
Guide
Chemical
AISI: Nominal. 0.4 C, I .-IO Mn. 2.75 Si. Composition. I.50 Cr. 0.40 MO. AISI/UNS (T41906): 0.40 to 0.50 C. I.20 to I .SO hln. 3.OOto2.SOSi. 1.20to 1.50Cr.0.30t00.50 Mo.0.30to0.10V
Similar QQ-T-570
Steels (U.S. and/or
Foreign).
ASTM
~68 I (S-6):
FED StreSS RekVing. Optional. Heat to 650 to 675 “C t 1200 to I245 “FI and hold for I h per inch of cross section tmmimum of I h). Cool in air
(S-6)
Characteristics.
High safety in hardening. Will decarhurize readil! if not adequately protected. One of the more highly alloyed grades. making it amclng the more expensive S series steels
Forging. Start forging at 1010 to II20 forge below 870 “C f I600 “F)
Recommended Normalizing. Annealing.
approximateI> I h for light sections and small furnace charges. to approximately 1 h for heav) sections and large charges. Cool at a rate not to exceed I-I “C (25 “F) per h. hlaximum rate not critical after cooling to approximately 5 IO “C (950 “F). Typical annealed hardness, 192 to 229 HB
Heat Treating
“C (l8SO to 2050 “F). Do not
Hardening. Heat slowI!. Preheat at 760 “C ( 1400 “F). Austenitize at 915 to 955 “C t 1680 to 1750 “F), hold for 10 to 30 min. then quench in oil. As-quenched hardness. 56 to 60 HRC Stabilizing.
Practice
Do not normalize
Heat to 800 to 830 “C ( 1475 to 1525 “F). Use lo\\er limit for small sections and upper limit for !wpe sections. Holding time I aries from
Optional. For intricate shapes. stress relieve temper at IS0 to 160 “C (300 to 320 ‘F) briefl!. Refrigerate at -100 to -195 “C (-150 to -320 “F). Temper immediately after p&artreaches room temperature
Tempering. tempered HRC
Temper at 205 to 3 IS “C r-100 to 600 “FL Approximate hardness as it corresponds to tempering temperature. 56 to 51
Tool Steels I531
Recommended l
Rough machine
l
Stress relieve
l
Finish machine
l
Preheat
Processing
(optional)
Sequence
l l
Austenitize Quench
l
Stabilize (optional)
l
Temper
l
Final Lwind to size
S6: Isothermal Transformation Diagram. S6 containing 0.43 C, 1.35 Mn, 2.25 Si, 1.35 Cr, 0.40 MO, 0.30 V. Austenitized at 925 “C (1695 “F) and oil quenched. As-quenched hardness, 60 HRC. Source: Crucible Steel
S6: Hardness vs Tempering Temperature. S6 containing 0.55 C, 0.97 Mn, 1.95 Si, 0.29 Cr, 1.07 MO, 0.25 V. Austenitized at 870 “C (1600 “F) and quenched in oil. Source: Teledyne VASCO
Tool Steels I531
s7
Chemical Composition.
AISI: Nominal. OS0 C. 1.10 Mo. 3.3 Cr. AISI/UNS (T11907): 0.45 to055 C. 0.20 to 0.90 hln. 0.20 to 1.00 Si. 3.00 to 3.50 Cr. I.30 to 1.80 Mo. 0.20 to 0.30 V (optional)
Similar Steels (U.S. and/or Foreign).
ASTM
~681 (S-7)
Hardening. Heat slowly. Preheat at 650 to 705 “C (IXIO to 1300 OF). VVhen using an open furnace. austenitize at 93 to 955 “C (I695 to 1750 ‘Fj. hold for IS to -IS min. For pack hardening, hold for ‘/2 h per inch of pack cross section. Quench in oil or air cool. Asquenched hardness. 60 to 61 HRC
Characteristics.
Stabilizing. Optional. For intricate shapes. stress relieve temper at IS0 to 160 “C (300 to 320 “F) brielly. Refrigerate at -100 to -195 “C (-150 to -310 “FL Temper immediately after part reaches room temperature
Forging.
Tempering.
Has highest hardenability of the S series steels and maximum softening resistance at elevated temperatures. Has moderate reststance to decarburization and grain growth Start forging at 1065 to I I?0 “C t 1950 to 2050 “Fj. Do not forge belou 93 “C ( I695 “F)
Recommended Normalizing. Do
Heat Treating
Practice
not nomrnlize
Annealing.
Heat to 815 to X-t5 “C (IS00 to IS55 “FL Use loiter limit for small sections and upper limit for large sections. Holding tulle varies from approximately I h for light sections and small furnace charges. to approximately 1 h for heavy sections and large charges. Cool at a rate not to exceed I4 “C (3 “F) per h. Maximum rate not critical after cooling to approximately 5 IO “C (950 “F). Typical annealed hardness. I87 to X3 HB
tempered HRC
Recommended l l l l l l l
Stress
Optional. Heat to 650 to 675 “C ( 1200 to I345 “Fj and hold for I h per inch of cross section (minimum of I h). Cool in air k?k?Ving.
Temper at 105 to 620 “C (-IO0 to I IS0 “F). Approximate hardness as it corresponds to tempering temperature, 57 to 45
l l
Processing
Rough machine Stress reliekc toptional) Finish machine Preheat Austsnitize Quench Stabilize (optionalj Temper Final grind to size
Sequence
532 / Heat Treaters
Guide
S7: Isothermal Transformation 900 “C (1650 “F)
S7: Size Change in Hardening. Corporation
Diagram.
S7. austenitized
at
S7: Hardness vs Tempering 940 “C (1725 “F)
Air cooled from 940 “C (1725 “F); tempered
Temperature.
S7. austenitized
1 h at heat; 25 mm (1 in.) round. Source: CarpenterTechnology
at
Oil-Hardening
Cold Work
Tool Steels
(0 Series) Introduction The standard oil-hardening cold worh tool steels for which data are gi\cn III this section are identified b! the symbol “0”. folloued b> the number5 I . 3. 6. or 7. As a group. their hardenability is much higher than that of the water-hardenmg tool steels tic’ series). and the! can. therefore. be hardened b> quenching in oil. Tjps 01 is by far the most uidely used. and is produced by \ irtuall> all of the tool steel mills. Some minor L ariations exist in the chemical composition of 01 steel; however. thebe variations do not affect heat treating procedures \ignificantl). Some of the carbon in 06 steel is in graphite form. which is sometimes a factor in the fabrication of intricate dies. The graphite particle\ in its microstructure also serve as a built-in lubricant that rsportedlj gibes better die life in deep dmuing operations. Type 07 sometime\ is uwd in dies that require the retention of sharp cutting edges-a prope$ enhanced b> a tungsten addition and higher carbon content. The 0 series sleek+ generally are normalized to produce a more uniformly refined gram structure. especialI> after forgrnp or pre\ IOUS heating to temperatures much higher than the recommended austenitizing temperature. N’hen tinished or semifinished tools are annealed. the) should be
protected from decarburtzation or carburization during annealing. Type 0 I steel can be cycle annealed. In most instances. stress relieving of tools prior to final hardcnmg does not lessen dktortion noticeably during hardening: hoHewr. preheating of the 0 steels will minimize distortion during subsequent hardenmg The optimum temperature range for quenching baths conststing of con\ sntional oils is SO to 70 “C t I20 to I60 “F). Agitation is recommended. Although usually quenched in oil. ~)ps 07 steel sometimes is quenched in \+ater or brine I\ hen masimum hardness is required and heav) sections are inLolLed. If control of distortion is particularly important. martempering sometimes is advantageous. A bath. oil. or molten salt. that is usually held approximately - I4 to 28 “C 115 to SO ‘F) above the hl, temperature is employed. The 0 steels should be tempered immediately after quenching that is. before the! reach room temperature. The most commonly used tempering range is I75 to 205 “C (345 to 100 “FJ. Time at temperature L arks N ith section size
01 Chemical COiIIpOSitiOn. AISI: Nominal. 0.90 C. I .OO hln. 0.50 Cr. 0.50 H’. AISI/UNS (T31501): 0.85 to I .OOC. I .OO to I .-!O hln. 0.50 Si ma. 0.30 Ni max. 0.40 to 0.60 Cr. 0.30 V max. 0.40 to 0.60 \k Similar Steels (U.S. and/or Foreign). QQ-T-570 (0-I): AFNOR AM-590 SKS 3.GUO-lSKS BOI
ASThl .-\681 to-1 L FED SXE J-437 tOI). J-l% 1011: (Ger.) DIN l.2510: tFr.1 2212 90 hlWCV 5: tJap.1 JIS G-I-IO-! SKS 21. G-l-404 94.G44O-l SKS 95: (Sued.1 SS 2110: (U.K.) B.S. 4659
Characteristics. Hi~hdimensional stnhilit> during heat treating RelatileI> shallow hardening. High resictance to decarhurirrltion. Veq high safety in hardening
I 1000 “FI at a rate not to exceed 32 ‘-‘C t-IO “F) per h. after which controlled cooling is not necessary. Tj pical annealed hardness. I83 to 2 I2 HB
Cycle Annealing.
Heat to 730 ‘c: ( I350 OF). hold for 4 h. Heat to 780 “C t 1435 “F). hold for 2 h. Cool to 690 “C ( I175 “F). hold for 6 h. Air cool
Stress k?h?ViIIg. Optional. Heat to 650 to 675 “C ( I200 to 124s “F) and hold for I h per inch of cross section I minimum of I h). Cool in air Hardening. Heat slowI!. Preheat at 650 “C t 1200 OF). Austenitize at 790 to8lS’Ctl455 to IS00 ‘F) for IO to30min. thenquenchinoil.Quenched hardness. 63 to 65 HRC Stabilizing.
Forging.
Optional. For intricate shqeb. stress relieve temper at IS0 to I60 ‘C 1300 to 320 “F) for 20 to 30 min. Refrigerate at -IOU to -195 “C (-150 to -3X “FL Temper tmmedintel! nli?r p,art reaches room temperature
hslou
Tempering.
Start forging at Y8O to 1065 ‘C t I793 to 1950 “FL Do not forge 8-U ‘C (IS55 “F)
Recommended
Heat Treating
Practice
Normalizing.
Heat tn 870 ‘C I 1600 “F). .After uniform through heating. holding time varies from approximately IS min for small section> to approsimatel> I h for larse sections. b’ork is cooled from temperature in still air
ing nppro\imate
Recommended l l l l
Annealing.
Heat to 760 to 790 “C t 1400 to 145s “FL Use lower tcmperature for small sections and upper temperature for large sections. Holding time is approximately I to 4 h. Use shorter time for light sections and small furnace charges. and longer time for heavy sections and large charges. For pack annealing. hold for I h per inch of cross section. Cool to S-IO “C
Temper at I75 to 260 “C (3-1 to SO0 “F) for a correspondtsmpered hardness of 62 to 57 HRC
l l l l l
Processing
Normulire Rough machine Stress relieve (optional) Finish machine Preheat Austcnitize Quench Temper Final pnnd to size
Sequence
534 / Heat Treaters
Guide
01: Isothermal Transformation Diagram. Composition: 0.85 C, 1.18 Mn, 0.26 Si, 0.50 Cr, 0.44 W. Critical temperature (AC,): 745 “C (1370 “F). Prior condition: annealed
01: isothermal
Transformation Diagram. Swedish grade showing percent pearlite and bainite as a function of time and transformation temperature. Source: Uddeholm Steels
01: Dimensional Changes and Hardness vs Tempering Temperature. Solid lines show approximate upper and lower limits of
01: Hardness vs Tempering Temperature. Austenitized at 790 to 815 “C (1455 to 1500 “F). Band approximately 2 HRC points wide
01: Hardness vs Tempering Temperature. Austenitized
hardness after tempering. Broken Shaded area, optimum temperature Steels
“C (1475 “F). Source: Universal-Cyclops
line, dimensional change. range. Source: Uddeholm
at 800
Tool Steels / 535
01: Length Changes vs Tempering Temperature
01: Dimensional Changes vs Tempering Temperature. Source: Latrobe Steel Co., Uddeholm Steels, Allegheny Ludlum Industries
536 / Heat Treaters
01: Microstructures.
Guide
(a) 3% nital, 1000x. As received (mill annealed). Dispersion of spheroidal particles of carbide In a matrix of ferrite. Characteristic of the fully annealed condition. (b) Nital, 1000x. Normalized by austenitizing at 900 “C (1650 “F) for 1 h and air cooling. Untempered martensite, some bainite. and retained austenite (white), from overheating. (c) 3% nital. 1000x. Austenitized at 815 “C (1500 “F), oil quenched (not tempered). Hardness, 66 HRC. Spheroidal carbide particles in a matrix of untempered martensite. (d) 3% nital, 1000x. Austenitized at 775 “C (1425 “F), oil quenched. Untempered martensite, undissolved carbide particles, In a ferrite matrix, from underheating. (e) Nital, 1000x. Austenitized 30 min at 800 “C (1475 “F). oil quenched briefly, then (before completely cool) tempered 2 h at 205 “C (400 “F). Carbide particles In tempered martensite. (f) Austenitized at 800 “C (1475 “F) for 30 mm, quenched briefly In oil, tempered at 205 “C (400 “F), for 2 h. Tempering was done too soon. Carbide particles in tempered martensite. (g) 3% nital, 1000x. Austenitized at 815 “C (1500 “F), oil quenched, tempered at 220 “C (425 “F). Hardness, 58.5 HRC. Spheroidal carbide particles in a matrix of tempered martensite. (h) 3% nital, 1000x. Austenitized at 815 “C (1500 “F), oil quenched, tempered at 425 “C (795 “F). Spheroidal particles of carbide (white dots) in a matrix of tempered martensite. (j) 3% nital, 1000x. Austenitized at 980 “C (1795 “F), oil quenched, tempered at 220 “C (425 “F). Coarse martensite (dark) and retained austenite (white), both resulting from overheating
Tool Steels / 537
01: Size Change in Hardening. Specimens were 25 mm (1 in.) round by 100 mm (4 in.) long; austenitized 20 min at 800 “C (1475 “F), oil quenched, then tempered 1 h at indicated temperatures. Source: Carpenter Technology Corporation
01: Jominy Hardenability.
Parts were austenitized at 800 “C (1475 “F). Source: Carpenter Technology Corporation
Tool Steels / 537
02 Chemical AISI/UNS
Composition.
AM:
Nominal.
0.90
C.
I 60
hln.
Ni max. 0.50 Cr max. 0.30 c’ max. 0.30 hlo ma\
Similar Steels (U.S. and/or Foreign). ASTM A681 to-?): FED QQ-T-570 (O-2); SAE J-137 102,. J-138 (02): tGer.t DIN 1.23-17; (Fr.1 AFNOR 90 hw 8. MS-SYO XI I 90 hl\’ 8: rL1.K.t B.S. 4659 tUS.A 02). 4659 BO?: cltal.) l!NI 88 hlnC’ 8 Kli Characteristics. of hardening. zation
Forging. hrlo~
Recommended
Heat Treating
Practice
(T31502): 0.85 m 0.95 C. I .-IO to I X0 Mr. 0.50 Si max. 0.30
br)
\/ec good nondsfomtinu properties. hledium depth high safety in hardenmp. High resistance to decarhuri-
Start forging at 980 to I OS0 “C t I795 to 1920 “Ft. Do not forge 8-15 “C ( I SSS “F)
Normalizing. Heat to 8-U ‘C r IS55 “F). After uniform through heating. holding ttme \aries from approximately IS tin for small sections to appro~mlatel! I h for large sections. Work is cooled from temperature in still air Annealing. Heat to 7.45 to 775 “C r 1370 to 133 “F). Use lower temperature for small sections and upper temperature for large sections. Holding time is appro~tmatrly I to -I h. ltse shorter time for light sections and small furnace charges. and longer time for heavy secttons and large charges. For pack annealing. hold for I h per Inch of cross section. Cool to S-IO “C ( 1000 ‘FI at a rate not to eweed _‘2. ‘C t-40 “F) per h. after which controlled coolmp IS not necessar!. T! pical annealed hardness. I83 to 2 I7 HB
538 / Heat Treaters
Guide
Recommended
stress Relieving. Optional. Heat to 650 to 675 “C (I 100 to 12-15 ‘F) and hold for I h per inch of cross section (minimum of I h). Cool in air
l
Hardening.
l
l
Heat siowi~. Preheat at 650 “C (I 200 ‘F). Austenitize at 760 to 800 “C (I400 to IA75 “F) for 5 to 30 mm. then quench in oil. Quenched hardness. 63 to 65 HRC
Stabilizing.
Cptionai. For intricate shapes. stress reiie\e temper at I50 to i60”C~300to320”F)for~Oto30min.Refrigenteat-i00to-l9S”Ct-i50 to -330 ‘F). Temper immediately after part reaches room temperature
Tempering. approximate
l l l l l l
Processing
Sequence
Nomlaiize Rough machine Stress relieve (optional) Finish machine Preheat Austemtize Quench Temper Final grind to size
Temper at I75 to 160 “C (315 to 500 “F) for a corresponding tempered hardness of 62 to 57 HRC
02: Isothermal Transformation
Diagram. Composition: 0.87 C, 1.78Mn,0.027P,0.010S,0.29Si,0.15Ni,0.20Cr,0.03Mo.Nose of curve is at 6 set for chemical composition. Source: Carpenter Steel
02: Jominy Hardenability.
Source:
Carpenter
Technology
Cor-
poration
02: Size Change in Hardening. Bar 25 mm (1 in.) in diam was oil quenched from 800 “C (1475 “F) and tempered 1 h at indicated temperatures. Source: Carpenter Technology Corporation
Tool Steels / 539
02: Isothermal Transformation Diagram. British grade. Nose of curve is at 12 set for chemical analysis. Percent pearlite and bainite. as a function of time and transformation temperature. Source: Jessop Saville
02: Hardness vs Tempering Temperature. Austenitized to 800 “C (1425 to 1475 “F) and tempered for 1 h
at 775
02: Microstructures. (a) Nital. 1000x. Annealed by heating to 725 “C (1335 “F). holding for 1 h per inch of section thickness and furnace cooling. Spheroidal carbide in a matrix of ferrite. (b) Nital, 1000x. Austenitized 15 min at 800 “C (1475 “F), quenched in oil. Some spheroidal carbide( white dots) in a matrix of untempered martensite. (c) Nital, 1000x. Austenitized and quenched same as (b), then tempered 1 h at 175 “C (345 “F). Some spheroidal carbide (white dots) in tempered martensite
Tool Steels / 539
06 Chemical Composition. AISI: Nominal. I .4S C. 0.80 hln. I .OO Si. 0.3 hlo. AlSl/UNS (T31506): I.25 to I.55 C. 0.30 to I.10 Mn. 0.55 to I.55 Si. 0.30 Ni max. 0.300 max. 0.10 to 0.30 hlo Similar
Steels (U.S. and/or Foreign).,\lsl
(O-6): FED QQ-T-570 (O-6): 1.2206: (Fr.) AFNOR A35590
SAE J437 (06). 2 132 I30 C 3
O-6: ASThl A681 J-l38 (06): (Gsr.1 DIN
Characteristics.Grnrrall~
IOH distortion \rith high safety in hardsninp. Contains graphite and is relativeI> deep hardening with high ahrnsion resistance. Not readily obtainable in a variety of sizes
Forging&u forging at 980 to IO65 “C ( I795 to 1950 “F). Do not forge heIon 8 IS “C ( IS00 “F)
Recommended
Heat Treating
Practice
Normalizing.Heat holding lime approximate11 still air
to 870 “C (1600 “F). After uniform through heating. varies from approximately IS nin for small sections to 1 h for large sections. Work is cooled from temperature in
Annealing.Heat
to 765 10 790 “C i 1410 to l-155 “FL Use lower temperature for small sections and upper temperature for large sections. Holding time is approximately I to 4 h. Use shorter time for light sections and small furnace charges. and longer time for heavy sections and large charges. For pack annealing hold for I h per inch of pack cross section. Cool at a rate not to exceed 6 “C ( IO “F) per h. From 705 “C ( I300 “F) to 510 “C (1000
540 / Heat Treaters
Guide
“F) cool at a rate of I4 “C (25 “Fj per h. hslaximum rate not critical after cooling below S-IO “C ( 1000 “FL Typical annealed hardness. I83 to 2 17 HB
Stress
Relieving.Optlonal.
Heat
IO
650
to
675 ‘C (I 100
and hold for I h per mch of cross section (minimum
to
12-U ‘Fb
of I h,. Cool in air
Tempering.Tsmper approximate
Recommended l l
HardeningAehrat
slowly to 650 ‘C ( I200 “FL Ausvnitire at 790 IO 81 S “C (l-155 to 1500 “F) for IO to 30 min. then quench in oil. Quenched hardness. 63 to 65 HRC
l l l l
Stabilizing.Op~ionnl.
For intricate shapes, slress relieve temper at I SO LO 160 “C (300 to 320 “F) for 20 to 30 min. Refrigerate at -100 to -19S ‘C i-150 to -320 “F). Temper immediately after part reaches room rsmpsrature
06: Hardness vs Tempering Temperature. Austenitized to 815 “C (1455 to 1500 “F) and tempered 1 h
at 790
at I75 to 3 IS ‘C (,3-U to 600 “F) for a corresponding tempered hardness of 63 to 58 HRC
l l l l
Normalize Rough machine Stress relies c loptionul Finish machine Preheat r\uslenilizr Quench Stnhilizs coptional) Temper Final grind to size
Processing
Sequence
J
06: Hardness vs Tempering Temperature. Hardness of a British grade of 06 tool steel as a function of austenitizing and tempering temperatures. The band represents upper and lower limits of hardness, and the shaded portion indicates the optimum tempenng range. Source: British Steel
06: Size Change in Hardening. Specimens were austenitized in salt at 800 “C (1475 “F) for 25 min, oil quenched, and tempered 1 h at temperature. Source: Carpenter Technology Corporation
Tool Steels
/ 541
06: Microstructures. (a) 3% nital, 1000x. Austenitized at 800 “C (1475 “F), oil quenched, tempered at 165 “C (330 “F). Partial-to-total decarburization (left), carbon-lean martensite (light gray), tempered martensite (dark gray), and graphite (black). (b) Nital. 100x. Austenitized at 790 “C (1455 “F) for 50 min, oil quenched, tempered at 205 “C (400 “F) for 2 h. Longitudinal section. Black streaks are elongated particles of graphite. (c) Nital. 1000x. Same steel, heat treatment and orientation as for (b), but shown at higher magnification. Structure consists of particles of carbide in tempered martensite, with some particles of graphite. (d) 3% nital. 1000x. Austenitized at 760 “C (1400 “F), oil quenched, tempered at 220 “C (425 “F). Spheroidal carbide and graphite in a matrix of tempered martensite and some ferrite (from underheating). (e) 3% nital, 1000x. Austenitized at 815 “C (1500 “F), oil quenched, tempered at 220 “C (425 “F). Structure is graphite (black) and carbide particles (white) in a matrix of tempered martensite (gray). (f) 3% nital, 1000x. Austenitized at 815 “C (1500 “F), oil quenched, tempered at 425 “C (795 “F). Graphite particles barely visible. Remaining structure is carbide particles in tempered martensite. (g) 3% nital, 1000x. Austenitized at 815 “C (1500 “F) and quenched in oil. Microstructure consists of particles of graphite (black) and spheroidal particles of carbide (white dots) in untempered martensite
542 / Heat Treaters
Guide
07 Chemical
Composition.
AlSl/UNS
AM: Nominal.
1.20 c. 0.75 Cr. 1.7s W.
(T31507): I. IO to 1.30 C. 1.00 Mn max. 0.60 Si max. 0.30 Ni
max. 0.35 to 0.85 Cr. 0.30 MO max. 0.40 V max. 1.00 to 2.00 W
Similar
Steels (U.S. and/or Foreign).
AISI O-7: ASTM ~681 (O-7); FED QQ-T-570 (O-7); (Ger.) DIN I.2414 1.2419. 1.2442. l.?Sl6, 1.2519: (Fr.) AFNOR A3S-590 3,141 I05 WC 13: (Jap.) JIS G-l404 SKS 2
Characteristics. Generally low hardenability although most wear resistant of 0 series steels. Hardenability is marginal. and water quenching may be required to obtain desired hardness, particularly in larger sections. Quench cracking may be a problem with the more drastic quench Forging. Start forging at 980 to 109s “C (I 795 to 2005 “F). Do not forge below 870 “C ( I600 “F)
Recommended
Heat Treating
Practice
Normalizing. Heat to 900 “C (I650 “F). After uniform through heating. holding time varies from approximately IS nun for small sections to approximately I h for large sections. Work is cooled from temperature in still air
StreSS F?ehhlg. Optional. Heat to 650 to 675 “C ( 1200 to 1235 “F) and hold for I h per inch of cross section (minimum of I h). Cool in air
Hardening. Heat slow Iy. Preheat at 650 “C (I 200 “F). If water quench is used. austenitize at 790 to 830 “C ( I-IS5 to IS25 “F) for IO to 30 min and quench in water for a quenched hardness of 61 to 66 HRC. To prevent cracking. do not let tool cool below 60 “C ( I10 “F) and temper immediately. If oil quench is used. austenitize at Xl5 to 885 “C (IS00 to 1625 “F) for IO to 30 min and quench in oil for a quenched hardness of 64 to 66 HRC. Sections larger than 38 mm ( I ‘12 in.) will be softer Stabilizing.
Optional. For intricate shapes, stress relieve temper at IS0 to 160 “C (300 to 320 “F) for 20 to 30 min. Refrigerate at -100 to -195 “C (-I SO to -320 “F). Temper immediately after part reaches room temperature
Tempering. mg approximate
Recommended l l l
Annealing.
Heat to 790 to 815 “C ( 1455 to IS00 “FL Use lower temperature for small sections and upper temperature for large sections. Holding time is approximately I to 4 h. Use shorter time for light sections and small furnace charges. and longer time for heavy sections and large charges. For pack annealing. hold for I h per inch of cross section. Cool to S-IO “C (1000 “F) at a rate not toexceed 22 “C t-IO “F) per h. after w hich controlled cooling is not necessary. Typical annealed hardness. I92 to 3 I7 HB
07: Hardness vs Tempering Temperature. Hardness as a function of austenitizing and tempering temperatures. Large uniform sections were austenitized at 800 to 830 “C (1475 to 1525 “F) and water quenched. Other sections were austenitized at 830 to 870 “C (1525 to 1600 “F) and oil quenched. Duration of tempering was lh
Temper at I75 to 290 “C (345 to 555 “F) for a correspondtempered hardness of 61 to 58 HRC
l l l l l l l
Processing
Sequence
Normalize Rough machine Stress relieve (optional) Finish machine Preheat Austenitize Quench Stabilize (optional) Temper Final grind to size
07:
Dimensional
Change
vs Tempering
Temperature.
Austenitized at 900 “C (1650 OF). Band shows approximate upper and lower hardness limits after tempering the steel when austenitized at 840 “C (1545 “F) and 900 “C (1650 “F). Shaded portion indicates optimum tempering range. Source: Bain and Grossman
Tool Steels / 543
07: Length Changes vs Tempering Temperature. Quenched from the indicated temperature. Allegheny Ludlum Industries
Source: Bain and Grossman and
07: Microstructures.
Nital, 1000x. Austenitized at 885 “C (1625 “F), quenched in oil, and then tempered at 205 “C (400 “F). Structure consists of undissolved particles of carbide (white) in a matrix of tempered martensite
Medium-Alloy, Cold
Work
Air-Hardening
Tool Steels
(A Series)
Introduction The medium-alloy. air-hardening sold pork tool steel\ comidsrcd in this section are tdentitied b) the letter .. A”. followed by the number% 2 through 4. and 6 through IO. All have high hwdennbilit) and harden rsadil) when cooled in ax. the rzcommrnded quashing medium. Ewspt for 11~s A IO. normalizing is not rrsommended for an! of th? A series aels All of these ~14s are usunll~ supplied in ths annzalsd condition bl the manufacturer and. thswfors. require annealing onI> after forglnp or \\rlding. or pnor to rehardwing. Stress rzlia tnp 1s psrformsd bet\vesn rouph and finish machining. or is gencrall~ limltcd to tools that cannot bs ground after hardening or to tools machined to final shape which can bs straightened after stress relieving and before linal heat treatmat. To minimirs distortion. these str’& are almost alwa~ 5 prsheatrd before bring austrnitirrd for hardening. Thq a-? au>trnitiz?d in molten salt or in \ arious type5 of furnaces. using gaseous atmospheres for protection against oxidation and/or daxrburir:ltion. Ths ~14s with th? Io\\N auzteniyizing temperatures, notably A-I, AS. and .A6. xt often austsnitized in molten lend or in furnaces without protective atmosphere\. The ubwws of protection is. ofcourse. a calculated risk. Excess~\sl~ high nustenitizinp temperatures promote the retention of austcnit? upon cooling and should be avoided. All A wieb steels. as previousI> noted. we quenched in air. The tempsring practicz~ for A series sterll~ arc ssxntiall> the same a\ those employed for the D and 0 series steels. Tempering is usualI> begun when the steel reaches a trmpsmturs of appro\imatcl> SO to 66 “C ( IN to
I SO “F) Douhls. und aen tnpl 12.tznipsrin_e i5 used to maximize transformotion of aubtenite to marwn~itr. Stabilizmg at subzero tempsratura is also rmplo!,sd. ai\rqs follo\rrd b! tcmpsring IO avoid craching ne\rl! tmnsfornisd niartensw. Ths .A wriss strfcls. notably A2 and .-\7. are often nitrided after hxdeninp and tempering. u hen that prssrncs of n nittided lqr‘r is ad\nntagzous to the spscitic applicatton Ths A tool steelj co\er a u ids ranpe ot carbon and alloy contents, but all have high hardsnubilit~ and harden rsadil) hy air cooling. All exhibit a high degree ofdirnen4onal stnbilit! in heat treatment. This propcrt) along N ith fair11 good aear resistance and modaxe price t,compared IO the cost of 125 chromium grades of the D ssrir~) mak the A grades popular for a multitude of tooling applkltion5 The most rendilj a\ ailnbk and I\ idelb used grade is AZ. It does not poswsb the fear r?si\tctncs of the D saws. the toughness of the S srrk. or the r?waanc‘s to sotisning at &\ntsd tr’mpa-aure of the H sew\. but II rates higher in the\e propsrtiss than ths mnnpnnesc ~)pcs of this series. The IOU -carbon 11pes AX and .-\Y offer greater shocb rr&nnce than th? other jt??Is In 1hi.i group. hut are lwer in \\ear resistance. Type A7. I\ hich ha> high carbon and \nnad~um content. e\hibitj mn\imum abrasion hut should be restricted to applications w ha-e toughness is not a resiwuw. prime considaxtion. ,A IO is a gruphitic \tssI. having properties similar to 06 ehwpt that .A IO i\ higher in hardsnahilit>.
A2 Chemical
Composition. AISI: Nominal. I .OO C. 5.00 Cr. I .UO hlo. (T30102): 0.95 IO I .05 C. I .OO hln mns. 0.50 Si ma\. 0.30 Ni max. 1.7s to 5.50 Cr. 0.90 IO I .-IO hlo. 0. IS to 0.5 I AISI/UNS
Similar
Steels (U.S. and/or
Foreign). .xYrhl ;\68 I I .A-?): FED WE J-137 (A~J. J-138 (A?): IC2r.I DIN 1.363: tFr.) 2731 Z 100 CDV 5: (Jap.) JIS G-MO-! SKD 12: ~S\rcd J SS 2260: (1l.K.) B.S. 4659 BA2
QQ-T-570 (A-2); AFNOR AM-590
Characteristics.
Deep hardening. \\iirh lo\r distortion and w-j high safety in heat treating. High resistance to wftening at &wed Iemperatures and medium rtaisrance to decarburizanon. Has a tadacb IO retain austenite. which usualI) is sliminavd or reduced 10 insignificant mnoun~s during tenipenng and double Irnipering
Forging.
Hea slofi Iy Preheat ai 650 to 675 ‘C i I X0 to I145 “F). Start forging 31 IO IO to IO95 ‘C ( 1850 IO 2005 “F). Do not forg? helow 900 ‘C ( I650 “F). Cool slow I>
Recommended Normalizing. Annealing.
Heat Treating
Practice
Do not normalize
Heat slowlj and uniformly IC) 845 to 870 “C ( IS55 to I600 ‘F). After soaking adequatrly for section size, rsstrict cooling to a ma\i-
mum rat of 22 “C l-10 ‘F) pa u hich a Fakr rate ma! bs used. This grade can b? isokrmnll~ from the annsaling tsmpsrnturs.
h until 5-W “‘C ( IO00 “F) is reached, after T> pica1 annealed hardness. Xl to 229 HB. anwaled l-q cooling to 760 .C ( l-100 “F) holdins fur 4 IO 6 h and air cooling
Stress RelieVing. Optional. Heat to 650 lo 675 T (I 200 IO 1245 ‘F) and hold for I h per inch of cross ssction (minimum of I h). Cool in air Hardening. Hex slo\~l!. Preheat at 700 -C ( l-155 “FI. atwcnilizr UI 93 IO 980 ‘C ( I695 to I795 “‘F). and hold at rsmprruturc for 20 min for small 1001s to 45 min for large tool>. Air cool ;I> c\cnl> as possibk on all sides. parricularl> u hen cool~np long 11~ dish T>p~cal quenched hardness. 62 LO 65 HRC Stabilizing.
Optional Lou -temperature trentmenl msy increase hmdnsss and improve dimenGonnl btubilitj bj reducing [he amount of rctalnrd nustenits. partisularl~ when temperatures nt the upper end of the austrnitizing range are used. It is safer and definiteI> wcomm?nded IO stress relieve temper at I50 to I60 ‘C (300 IO 320 “F) for 3 short period before refrigerating IO -85 “C t-120 “F). particularly for intricate shapss or tools having abrupt changes in vxlion sire. Temper immedin[ely atier tool reaches room tcniperature
Tempering. 1001 has cooled
Temptr immediarcl> 31 I75 IO 540 “C I 345 IO IO00 “FI after to SO IO 66 “C I I?0 IO IS0 ‘F). Double temper. allowing
Tool Steels / 545
tool to cool IO room temperature hsfors second ttmper. Range of hardness after tempering. 62 to 57 HRC. Tempsrinp he~wxn I75 IO 230 ‘C (345 to -l-IS ‘F) is recommended for maximum war resistance. and bewax 370 to 400 jC (700 to 750 “F) for masimum zhock wsistance
l l l l l
Recommended l l
Processing
Rough machin? Stre3s relisvs Ioptional)
Sequence
l l
Finish machine Prshzat Austcnitize Quench Stabilize coptional) Temper/double [emper Final grind
A2: Hardness vs Tempering Temperature. Austenitized at various temperatures and air cooled. Source: Universal-Cyclops
A2: Isothermal Transformation Diagram. 0.97 C, 0.48 Mn. 0.40 Si. 4.58 Cr, 1.04 MO, 0.25 V. Prior condition, annealed. Austenitizing temperature, 1010 “C (1850 “F)
546 / Heat Treaters
Guide
grade
A2: Austenitizing Temperature vs Surface Hardness. Composition: 1 .OOC. 0.50 Mn, 5.00 Cr, 1 .OO MO, 0.20 V, air cooled from the austenitizing temperature. Specimen size was 25 mm (1 in.) diam by 50 mm (2 in.) long. Source: Allegheny Ludlum Industries
A2: Tempering Temperature vs Hardness and Dimensional Change. Cooled in 75% hydrogen and 25% nitrogen gas from 945”C(1730”F).Contains1.00C,0.65Mn,0.30Si,5.20Cr, 1.00 MO, 0.25 V. Specimens, 25 mm (1 in.) diam, 50 mm (2 in.) long. 0, diameter change: 0, length change
A2: Austenitizing Temperature vs Retained Austenite. Composition: 1 .OOC, 0.61 Mn, 0.17 Si, 5.31 Cr, 1 .13 MO, 0.27 V, cooled at different rates
A2: Isothermal Transformation Diagram. Swedish austenitized at 950 “C (1740 “F). Source: Uddeholm
Tool Steels / 547
A2: Transformation of Retained Austenite. Transformation curves apply to structure at room temperature aftertempering. 0 30% transformed 0 50% transformed, A 75% transformed, A 90% transformed, 0 100% transformed for A2 tool steel containingl.OOC,0.61 Mn,0.014P,0.013S,0.17Si,5.31Cr, 1 .I 3 MO. 0.27 V. air cooled from 980 “C (1795 “F)
A2: Size Change in Hardening. Bar 25 mm (1 in.) in diam was air quenched from 955 “C (1750 “F); tempered 1 h at temperature. Source: Carpenter Technology Corporation
A2: Typical Tensile and Yield Strengths. Technology Corporation
Source: Carpenter
546 / Heat Treaters
Guide
A2: Microstructures. (a)49b nital, 1000x. Annealed by austenitizing at 845 “C (1555 “F) and furnace cooling. Massive carbide and fine spheroidal carbide particles in matrix of ferrite. (b) 3% nital, 1000x. Austenitized at 980 “C (1795 “F) and air cooled (not tempered). 64 HRC. Spheroidal carbide particles in matrix of untempered martensite. (c) 49” nital. 1000x. Austenitized at 955 “C (1750 “F), air cooled. tempered at 150 “C (300 “F). Spheroidal carbide particles in matrix of tempered martensite. See (f). (d) 4% nrtal, 1000x. Austenitized at 955 “C (1750 “F), air cooled to room temperature, tempered at 540 “C (1000 “F). Particles of carbide (both massive alloy carbide and spheroidal carbide in matrix of tempered martensite. See (e). (e) 4% nital. 1000x. Austenitized at 925 “C (1695 “F), air cooled, tempered at 540 “C (1000 “F). Structure similar to (d), except considered underheated in austenitizing because more undissolved small carbide particles are present. (f) 4% nital, 1000x. Austenitized at 980 “C (1795 “F), air cooled to room temperature, Tempered at 150 “C (300 “F). Structure same as (c). except grains are coarser because austenitizing temperature was higher. (g) 3% nital. 1000x. Austenitized at 980 “C (1795 “F), air cooled. tempered at 175 “C (345 “F). 63 HRC. Large alloy carbide particles and small spheroidal carbide particles in matrix of tempered martensite. Grain boundaries (black lines) barely visible. (h) 3% nital. 1000x. Austenitized at 980 “C (1795 “F), air cooled. tempered at 540 “C (1000 “F). Hardness, 53 HRC. Particles of carbide (both massive alloy carbide and spheroidal carbide) in matrix of tempered martensite. (j) 3% nital, 500x. Austenitized at 980 “C (1800 “F), air cooled, tempered at 175 “C (345 “F). Longitudinal section. Large and small spheroidal carbide particles in tempered martensite. Streaks are sulfide stringers
Tool Steels / 549
A3 Chemical Composition. AISI: Nominal. I.3 C. S.00 Cr. I.00 hlo. I .OOV. AISl/UNS (T30103): I.20 IO I .X1 C. O.-l0 to 0.60 hln. 0.50 Si max. 0.30 Ni max. 4.75 to 5.50 Cr. 0.90
Similar QQ-T-570
IO I .-IO
MO.
Steels (U.S. and/or Foreign). (A-31, FED QQ-T-S70
0.80
to
ASTM
I
.-IO V A681 (~-31:
FED
(A--lI
Characteristics. EssenIially similar IO an A2 steel. with 03 carbon and 0.7s vanadium added for increased itear resistance. AustenItizIng temperature is IO “C I IX “F) higher. and soah time IS longer than for AZ. .A deep air-hardening steel having lovv disIortion and verb high safet, in heal IrraIing. High resistance to softening a~ elevated temperatures. and medium IO high resisIancc to decarhunzation. Has a Iendency to retam austcniIe. u hich is usually eliminated or reduced IO insignificant amounts during Icmpering and double tempenng Forging. forging
( I650
Heat slo\r I\. PrcheaI at 650 to 67S -C t I700 to 1?-l5 “Ft. Start at 1010 IO 1063 ‘C (I850 to l9SO “Fl. Do not forge b&u YOO “C “F). Cool slon 1)
Hardening. Heat slowI). Preheat at 790 “C I1355 “F). austenitize at 955 to IO1 0 “C I I750 to I850 “Fl. and hold at temperature for 3 min for small tools to 60 nun for large tools. Air cool as evenly as possible on all sides. particularly u hen cooling long Flat dies Stabilizing.
Optional. Low-temperature treatment may increase hardness and improve dimensional srability b) reducing the amount of retained austenite. parncularl~ \+ hen temperatures at the upper end of the ausIeniIizing range are used. It is safer and definiteI> recommended to stress relieve Ittmper at I SO to I60 “C I300 to 320 “FJ for a short period before refrigerating to -85 ‘C I-l 20 “FJ. particularI!, for inuicate shapes or tools having abrupt changes in section size. Temper immediaIely after tool reaches room Iemperature
Tempering.
Temper immediateI> at I75 to S-40 “C (315 to 1000 “F) after tool has cooled to SO to 66 “C I I20 IO IS0 “Ft. Double Iemper. allowing tool to cool to room temperature before second temper. Range of hardness after tempering, 65 to 57 HRC
Recommended Recommended Normalizing.
Heat Treating
Practice
l l
Do not nomtalize
l
Annealing.
l
StreSS Relieving. Optional. and hold for I h per Inch ofcross
Note: Transformation applicable IO A3
Heat to 650 lo 675 ‘C I I200 to I Z-IS “F) section (minimum of I ht. Cool in air
l l l l
Sequence
Rough machine Slrsss rclis\s IoptIonal t Finish machine Preheat Austenilizs Quench Slahilize Ioptional) Temp4double Iemper Final grind
Heat slowly and uniformI) to 845 to 870 ‘C I ISSS to I600 ‘F,. After soahing adequaIel1 for section size. restricI cooling to a mahimum raIc of 22 ‘C (10 “Fl per h until S-10 “C II000 “Fl Is reached. after which a fasIrr rate ma) be used. Typical annealed hardness. 107 10 229 HB. This grade can he isothermall> annealed h> cooling to 760 C I l-l00 “F) from the annealing temperature. holding for-l to 6 h and air cooling
l
Processing
and Icmpering
data for A:! tool steel are roughly
Tool Steels / 549
A4 Chemical
Composition. AISI: Nominal. I .OCJC. 2.00 hln. 5.00 Cr. I .OO MO. AISI/UNS (T301O-t): 0.95 to I .05 C. I .X0 to 2.20 hln. 0.50 Si mas. 0.30 Ni mah. 0.90 to 7.10 Cr. 0.90 to I .A0 Mo
which a taster rate ma! be used. Typical anneAcd hardness. 200 to 241 HB. For minimum hardness. a second a~tal can he used. Repeat the cycle wing 730 “C ( I350 “F) a5 the anncaling temperature
Similar
stress Relieving. Optional. Heat to 675 to 705 “C ( I245 to 1300 “n and hold for I h per inch of cross section (minimum of I h). Cool in air
Steels (U.S. and/or
QQ-T-570
Foreign).
ASTM
A681 (A-4~: FED
t&l)
Characteristics. A manganese-allobed air-hardening tool steel. Compared to A?. the chromium content has been reduced from 5 to I %. and manganese has been increased from I to 3. Ha> the ndifantagr of a loi< austenitizing temperature. Isothermal characteristics simihar to A2 steel. Classified as deep hardening. Among tool steels ha\ mg lowest distortion in heat treating. Medium to high resistance to decsrhurization
Hardening. Heat slo\r I!. Preheat at 675 ‘C ( I245 “F). austenitize at 815 to 870 ‘C t I500 to I600 “F). and hold at temperature for IS min for small tools to 90 min for large tools. Quench b! air cooling as evenly as possihle on all sides. particularI> \\ hen cooling long flat dies. As quenched hardness. 61 to64 HRC
Forging.
Stabilizing.
Heat slot\ I!. Preheat at 650 to 675 “C t I ZOO to 1715 “FI. Start forging at IO IO to IO95 ‘C I 18.50 to ZOOS “F). Do not forge belo\i 900 “C ( 1631 ‘F) Cool slou I)
Recommended Normalizing. Annealing.
Heat Treating
Practice
Do not normalize
Heat slo\\ Iy and uniformI> to 740 to 760 “C I I365 to 1400 “FJ. After soaking adequateI> for section size. restrict coolinp to a ma\imum rate of I5 “C (25 “F) per h until S-IO “C t 1000 “F) is reached. after
Optional. Lo\\-t~mpernture treatment may increase hardness and improve dimsnknal stabilit! by reducing the amount of retained austenite. particularly when temperatures at the upper end of the austenitizing range are used. It is safer and definitely recommended to stress relieve temper at I SO to I60 “C (300 to 3X “F) for a short period before refrigeratmg to -85 “C t-l 20 “F). particularly for intricate shapes or tools having ahr~~pt changes in section size. Temper immediately after tool reaches room temperature
Tempering.
Temper immediateI, at I75 to 13 “C (34 to 795 “F) after tool has cooled to SO to 66 ‘C I I20 to IS0 “F). Douhle temper, allowing
550 / Heat Treaters
Guide
tool to cool to room temperature after tempering, 62 to 54 HRC
before second temper. Range of hardness
l l l
Recommended l l l
Processing
Sequence
l l
Rough machine Stress relieve (optional) Finish machine
A4: Hardness vs Tempering Temperature. “C (1555 “F) and cooled in air
l
Austenitized
at 845
Preheat Austenitize Quench Stabilize (optional) Temper/double temper Final grind
A4: Hardness vs Tempering Temperature. Austenitized at 815 “C (1500 “F) and at 850 “C (1560 “F) and cooled in air. Data represent upper and lower limits of hardness
550 / Heat Treaters
Guide
A6 Chemical
Composition. AISI: Nominal. 0.70 C. 2.00 Mn. I .OO Cr. 1.25 MO. AISI/UNS (T30106): 1.25 to 1.55 C. 0.30 to I.10 Mn. 0.55 to I.50 Si, 0.30 Ni max. 0.30 Cr max, 0.20 to 0.30 MO
tools to 45 min for large tools. 4ir quench. Typical to 63 HRC
quenched hardness. 59
Stabilizing.
Characteristics.
Optional. Low-temperature treatment may increase hardness and improve dimensional stability by reducing the amount of retained austenite. particularly when temperatures at the upper end of the austenitizing range are used. It is safer and definitely recommended to stress relieve temper at IS0 to 160 “C (300 to 320 “Ft for a short period before refrigerating to -85 “C t-120 “F). particularly for intricate shapes or tools having abrupt changes in section size. Temper immediately after tool reaches room temperature
Forging. Heat slowly. Start forging at IO-10 to I I20 “C ( 1905 to 2050 “F). Do not forge below 870 “C ( I600 “F)
Tempering.
Similar QQ-T-570
Steels (U.S. and/or Foreign). (A-6);
(U.K.)
ASTM
A68 I (~-6);
FED
B.S. 4659 BA6
Has properties roughly similar to A3 except with lower carbon content. Among the lowest in distortion in heat treating. Deep hardening, with high safety in hardening. Medium resistance to softening at elevated temperature. and medium to high resistance to decarburization
Recommended Normalizing.
Heat Treating Practice
Do not normalize
Annealing.
Heat SIOH Iy and uniformly to 730 to 745 “C ( I350 to 1370 “F). After soaking adequately for section size. restrict cooling to a maximum rate of 15 “C (25 “F) per h until 540 “C (1000 “F) is reached. after which a faster rate may be used. Typical annealed hardness, 2 I7 to 248 HB.
Stress kdieVing.
Optional. Heat to 675 to 705 “C ( IX5 to I300 “F) and hold for I h per inch of cross section (minimum of I h). Cool in air
Temper immediately at I50 to 425 “C (300 to 795 “F) after tool has cooled to 50 to 66 “C (I 20 to 150 OF). Double temper, allowing tool to cool to room temperature before second temper. Range of hardness after tempering. 60 to 51 HRC
Recommended l l l l l l l
Hardening.
Heat slowly. Preheat at 650 “C ( 1200 “F), austenitize at 830 to 870 “C ( I525 to I600 OF). and hold at temperature for 20 min for small
l l
Processing
Rough machine Stress relieve (optional) Finish machine Preheat Austenitize Quench Stabilize (optional) Temper/double temper Final grind
Sequence
Tool Steels / 551
A6: Hardness vs Tempering Temperature. Austenitized
at 845 “C (1555 “F) and air cooled. Hardness, 62 HRC. Source: Universal-Cyclops
A6: Length
Changes
vs Tempering
Temperature.
Austenitized at 845 “C (1555 “F) and air cooled. Hardness, 62 HRC. Source: Allegheny Ludlum Industries and Catpenter Steel
A6: Tempering
Characteristics
vs Dimensional
Change.
Austenitized at 830 “C (1525 “F) and 870 “C (1600 “F) and air cooled, showing upper and lower limits of hardness. Dimensional changes. austenitized at 845 “C (1555 “F) and air cooled. Shaded portion indicates optimum tempering range which coincides with lowest dimensional change. Source: Carpenter Steel
552 / Heat Treaters
Guide
A6: Isothermal Transformation
Diagram. Austenitized
“C (1545 “F). Source: Carpenter Technology
A6: Typical Tensile and Yield Strengths. Technology
Corporation
at 840
Corporation
Source: Carpenter
Tool Steels / 553
A6: Microstructures.
(a) Nital. 1000x. Annealed by heating to 730 “C (1350 OF), holding 1 h per inch of section thickness and furnace cooling. Structure fine spheroidal carbide In matrix of ferrite. (b) Nital. 1000x. Austenitized !+ h at 845 “C (1555 OF), air cooled, and tempered 1 h at 175 “C (345 “F). Fine martensite matrix with a few undissolved carbide particles (white specks)
Tool Steels / 553
A7 Chemical Composition. AISI: Nominal. 2.2.i C. 5.25 Cr. I .OO MO. -t.75 V. 1.00 W (optional). AlSI/llNS (T30107):3.OOro2.85C.O.80hln max. 0.50 Si max. 0.30 Ni max. 5.00 to 5.75 Cr. 0.90 to I .-to hlo. 3.90 to 5.15v.0._501o l.-lOI~ Similar
Steels (U.S. and/or Foreign).
QQ-T-S70
.ASThl
~681 (A-7);
FED
r A-7)
Characteristics. Contains the highest carbon content of the A series steels. along with -I.755 vanadium and SG chromium. Deep hardening u ith a relatively IOH austenitizinp tempernture. Low in distortion. 1~ith high resistance to softening at elevated temperatures. and medium resistance to decarburizntion Forging.
Heat slowly. Preheat at 6SO to 675 “C ( I ZOO to I Z-IS “F). Start forging at 1050 to I IS0 “C I 1970 to 2 I00 “Ft. Do not forge belou 980 “C r 1795 ‘F)
Recommended Normalizing.
Heat Treating
Practice
Do not normalize
Annealing.
Heat slowly and unifomtlj to X70 to 900 “C I 1600 to I650 “Ft. After soaking adequately for section size. restrict cooling to a maltmum rate of 30 ‘C (55 “F) per h until S-10 ‘C t 1000 “Ft is reached. after u hich a faster rate mav be used. T) plcal annealed hardness. 135 to 262 HB
Stress Relieving.
tools to 60 min for large tools. Air cool as evenly as possible on all sides. particularly when cool+ long flat dies. Typical quenched hardness. 64 to 67 HRC
Stabilizing.
Optional. Low-temperature treatment may increase hardness and improve dimensional stnhility by reducing the amount of retained austenite. particularly when temperatures at the upper end of the austenitizinp range are used. It is safer and definitely recommended to stress relieve temper at IS0 to I60 ‘C (300 to 330 “F) for a short period before refrigerating to -85 ‘C r-130 ‘Ft. particularly for intricate shapes or tools having abrupt changes in section size. Temper immediately after tool reaches room temperature
Tempering.
Temper immediately at I SO to S-10 “C (300 to 1000 “F) after tool has cooled to SO to 66 “C r I20 to I SO “Ft. Double temper. allowing tool to cool to room temperature before second temper. Range of hardness after tempering. 67 to 57 HRC
Recommended l l l l l
Optional. Heat to 650 to 675 “C r 1200 to I Z-15 “Fr and hold for I h per inch of cross section rmmtmum of I ht. Cool in air
l
Hardening.
l
Heat slowly. Preheat at 8 IS “C r I SO0 “F). austenitizs at 955 to 980 “C (I 750 to I795 “Ft. and hold at temperature for 30 min for small
l
l
Processing
Rough machine Stress relic\ 5 coptional t Finish machine Preheat Austcnitizs Quench Stabilize toptionnlt Temper/double temper Final grind
Sequence
554 / Heat Treaters
A7: Tempering
Guide
Characteristics
vs Dimensional
Change.
Austenitized at 870 “C (1800 “F) and 925 “C (1695 “F) and air cooled. showing upper and lower limits of hardness. Dimensional changes for A7 tool steel, austenitized at 925 “C (1695 “F) and air cooled. Shaded portion shows optimum range which coincides with lowest dimensional change
A7: Hardness vs Tempering Temperature.
13.5 mm (l/2 in.)
plate austenitized at 955 “C (1750 “F) and air cooled. Hardness, 67 HRC. 76.2 mm (3 in.) cubes austenitized at 980 “C (1795 “F) and oil quenched. Hardness, 66 HRC. Source: Universal-Cyclops
A7: Austenitizing
Temperature vs As-Quenched
Hardness.
Composition: 2.30 C, 0.70 Mn, 0.40 Si, 5.25 Cr, 1 .lO MO, 4.75 V, 1 .lO W. air quenched
A7: Microstructures. (a) 4% nital. 1000x. Box annealed at 900 “C (1650 “F) for 1 h per inch of container thickness and cooled at no higher than 25 “C (50 “F) per h. Structure massive alloy carbide and spheroidal carbide in a ferrite matrix. (b) 4”b nital. 1000x. Austenitized at 955 “C (1750 “F), air cooled, tempered at 150 “C (300 “F). Structure massive alloy carbide (white areas) and a few spheroidal carbide particles in matrix of tempered martensite. (c) 4% nital, 1000x. Austenitized at 955 “C (1750 “F), air cooled, tempered at 315 “C (600 “F). Structure massive alloy carbide and a few spheroidal carbide particles in matrix of tempered martensite.
(continued)
Tool Steels / 555
A7: Microstructures.
(continued) (d) Nital, 100x. Preheated at 675 “C (1245 “F), austenitized at 980 “C (1795 “F), air cooled, tempered at 175 “C (345 “F). See (e) and (9 for clear resolution of particles. (e) Nital, 500x. Same steel and heat treatment as (d), except at higher magnification. Structure large and small carbide particles in matrix of tempered martensite. Some retained austenite. (f), 1000x. Same steel and heat treatment as (d), except higher magnification. Evidence of retained austenite (light gray). Massive carbide particles increase wear resistance of steel surface
Tool Steels / 555
A8 Chemical
Composition.
1.75 W. AISI/UNS
AISI: Nominal. 0.55 C. 5.00 Cr. I.15 hlo. (T30108): 0.W to 0.60 C. 0.50 Mn mas. 0.75 to 1.10
Si. 0.30 Ni max. 1.75 to 5.50 Cr. I. I5 to I.65 MO. 1.00 to I.50 W
Similar
Steels (U.S. and/or
QQ-T-570 (A-8): (Ger.) DfN (Jap., JIS GUM SKD 6’
Foreign). ASTM ~681 (A-&); FED 1.2606: (Fr.) AFNOR 3432 Z 38 CDW 5:
Characteristics. One of the toughest of the 55, Cr steels in the A series. containing a relatively low 0.55% C. Except for the lower carbon content and the addition of I.%% W. it is similar to the vvidely used 42 grade. High resistance to softening at elevated temperature. Deep hardening. and among the lowest in distortion and the highest in safety in hardening of the tool steels. with medium resistance to decarburization Forging.
Heat slowly. Preheat at 650 to 67s “C ( I200 to IX5 “F). Start forging at 1065 to I I SO “C ( 1950 to 2 IO0 “F). Do not forge belou 915 “C (I695 “F)
Recommended Normalizing.
Heat Treating
Practice
Do not normalize
Annealing.
Heat slowly and uniformly to 845 to 870 “C t I SSS to 1600 “F). After soaking adequately for section size. restrict cooling to a maximum rate of 22 “C (-10 “F) per h until S-IO “C t 1000 “F) is reached. after which a faster rate ma) he used. Typical annealed hardness. I92 to 223 HB
Hardening. Heat slou ly. Preheat at 790 “C (I-155 “F). austenitize at 980 to 1010 “C t I795 to 1850 “F). and hold at temperature for 20 min for small tools to -15 min for large tools. Air cool. As-quenched hardness. 60 to 61 HRC Stabilizing.
Optional. LOM-temperature treatment may increase hardness and improve dimensional stability hg reducing the amount of retained austenite, particularly I\ hen temperatures at the upper end of the austenitizing range are used. It is safer and definitely recommended to stress relieve temper at IS0 to 160 “C (300 to 330 “F) for a short period before refrigerating to -8s “C t-l 30 “F). particularly for intricate shapes or tools having abrupt changes in section size. Temper immediately after tool reaches room temperature
Tempering.
Temper immediately at I75 to 595 “C (US to I I05 “F) after tool has cooled to 50 to 66 “C t 120 to IS0 “F). Double temper. allowing tool to cool to room temperature before second temper. Range of hardness after tempering, 60 to SO HRC
Recommended l l l l l l l
Stress Relieving. Optional. Heat to 650 to 675 “C ( I200 to I ?-IS “F) and hold for I h per inch of cross section (minimum of I h). Cool in air
l l
Processing
Rough machine Stress relieve toptional) Finish machine Preheat Austenitize Quench Stabilize topttonal) Temperldouhle temper Final grind
Sequence
556 / Heat Treaters
Guide
A9 Chemical
COIIIpOSitiOn.
I.40 hlo. 1.00 V. AISI/UNS
AISI: Nominul. 0.50 C. I.50 Ni. 5.00 Cr. (T30109): 0.X IO 55 C.O.SO hln max.095
to I. IS Si. I .?I to I.75 Ni. 4.75 to 5.50 Cr. 1.30 to I .80 hlo. 0.80 to I .-IO I
Similar
Steels (U.S. and/or
QQ-T-S70
Foreign).
.ASThI ~681 t~-o~:
FED
t A-9 J
Characteristics. Similar to AX in IOU carbon content. except with slightI> higher allo) content. hlxked secondaq hardening characteristics and usually tempered in the 5 IO to 620 “C to50 to I I SO “F) range. High in resistance to softening at elevated temperatures. deep hardening. and \ec IOH in distortion. Among the highest in safety in hardening. u ith medium resistance to decarburization
Hardening. Heat SIOU I\. Preheat at 790 ‘C I I-lSS ‘F). austenitize at 980 IO 1025 C I 17% to I875 ‘FI. and hold at temperature for XI nun for small tools to -IS nun for large rook. r\ir quench. Typical hardness. 56 to 58 HRC Stabilizing. Optional. Low-temperature treatment ma) increase hardnebs and improts dimensional stabilit) by reducing the amount of retained austenire. particularly u hen temperatures at the upper end of the austenitizing range are used. It is safer and definite11 recommended to stress relieve temper at I SO to I60 “C (300 to 320 ‘F) for a short period before refrigerating to -85 ‘C t-l 20 “FI. particularI> for intricate shapes or tools having abrupt changes in section size. Temper immediately after tool reaches room temperature Tempering.
Heat slowly. Preheat at 650 IO 675 “C t 1200 to 124 ‘F). Smrt forging at 1065 to I IS0 “C t loSO to 2 IO0 “F). Do not forge below 925 “C ( I700 ‘F)
Temper immediately at 5 IO to 620 “C (950 to I IS0 “F) after tool has cooled to SO IO 66 C t I20 to I.50 >F). Double temper. allowing tool to cool to room temperature before second temper. Range of hardness after tcmpsnng. 56 to 35 HRC
Recommended
Recommended
Forging.
Normalizing.
Heat Treating
Practice
Do not normalize
Annealing.
Heat SIOU I! and unifomtil to X45 to 870 C r IS55 to I600 ‘F). After soaking adequateI> for section size. restrict cooling to a maximum rate of IS “C (35 “F) per h until S-IO ‘C I 1000 “F) is reached. after u hich a faster rate may he used. Typical annealed hardness. Z 12 IO ?-I8 HB
l l l l l l l
Optional. Heal to 6%) to 675 ‘C t I ZOO to 12.45 “F) and hold for I h per inch of cross section tmimmum of I h) Cool in an Stress
RdieVing.
l l
Processing
Sequence
Rough machine Stress relieve toptional) Finish machine Preheat .Austenitizs Quench Stabilize toptronal) Temper/double temper Final grind
A9: Hardness vs Tempering Temperature. Austenitized at 980 “C (1795 “F) and 1010 “C (1850 “F) and cooled in air. Source: Universal-Cyclops
Tool Steels / 557
A9: Typical Room-Temperature Tensile and Yield Strengths. Source: Carpenter Technology Corporation
A9: Typical Source:
Room-Temperature
Carpenter
Technology
Charpy V-Notch Impact Data. Corporation
Tool Steels / 557
Al0 Chemical
Composition. AH: Nommal. I .3S C. I .X0 hln. I.25 Si. I.80 Ni. I.50 hlo. AISI/UNS (T30110): I.25 to I.50 C. I 60 to 2.10 hln. 1.0010 l.SO Si. l.SS to 3.05 Ni. I.25 w l.7S hlo
Similar QQ-T-S70
Steels (U.S. and/or Foreign).
ASTM
;\68 I I A- 10,: FED
(A-IO)
Characteristics.
hlangunese air hardening bteel. Carbon and silicon hish enough to precipitate out some curhon in the grnphitis form. usualI> approximateIF 0.3% carbon. hlcdium IO high in machinabilit!. Deep hardening and among the lowest of tool ~elb in distortion in heat treating. hlsdium in toughness and resistance to softening at elevated temperature. high in wear resistance. and medium to high in resistance to decarhurizntion
Forging.
Hear slo\% I). Preheat at 650 to 675 ‘-‘C I I X0 to I245 “F). Sinrt forging at YXO to IOSO “C ( I795 to 1920 “FL Do not forge bslw 870 “C (IhOO’F)
Recommended
Heat Treating
Practice
Normalizing. Heat IO 7YO “C (I455 ‘FI. Holding time. after uniform through heating. varies from npproximatel~ IS min. for small sections. to approaimatclq I h. for lqe sections. Cool from temperature m still air
Annealing.
Heat slog I) and unifomti) to 76s to 795 “C. (I410 to 1360 “F). After waking adsquntel, for section size. restrict cooling to a maximum rate of IO ‘C ( IS “F) per h until 510 “C (950 OF) is reached. after M hich a faster rate may be used. T> pical annealed hardness, 235 to 269 HB. For minimum hardness a second anneal can be used. Repeat the cycle using 730 “C ( l3SO ‘;F) 3s the austenitiring temperature. An eight-step annealing qcle has been recommended. as follows: He31 IO 780 ‘-C I I-l.15 ’ FJ and hold for 2 h Cool to S-IO “C ( I OOO‘FI at 22 “C c-lo “F) per h Air cool to room lemperature Rehsat IO 780 “C ( l-135 ‘F, and hold I h per inch of section Cool to 680 ‘C I 1255 “F, at an) con\ enient rate Equalize at 680 “C (I 2% “F) for 2 h Cool IO S IO “C (9SO “F) at a rate not to exceed 8 “C ( IS “F) per h Air cool to room temperature StreSS Relieving. Optional. Heat to 650 to 675 “C (1200 to 1245 “F) and hold for I h per inch of cross section Iminimum of I h). Cool in air
Hardening. Heat slot\ 1~. Preheat at 650 “C ( 1200 “F). austenitize at 790 to 8 IS “‘C ( 1154 to I SO0 “F). and hold ;I[ temperature for 30 min for small
558 / Heat Treaters
Guide
tools to 60 min for large tools. Air cool as evenly as possible on all sides. particularly when cooling long flat dies. Typical quenched hardness. 62 IO 64 HRC
Stabilizing. Optional. Lou-temperature treatment may increase hardness and improve dimensional stabilitj by reducing the amount of retained austenite. particularly when temperatures at the upper end of the austenitiring range are used. It is safer and definitely recommended IO stress relieve temper at I50 IO 160 “C (300 IO 320 “F) for a short period before refrigerating to -85 “C (-120 “F), particularly for intricate shapes or tools having abrupt changes in section size. Temper immediately after tool reaches room temperature Tempering.
Temper immediateI> at I75 to -US “C (345 to 795 “F) after tool has cooled to SO to 66 “C ( I20 to I SO “F). Double temper. allowing
tool to cool to room temperature after tempering. 62. IO 55 HRC
Recommended l l l l l l l l l
before second temper. Range of hardness
Processing
Sequence
Rough machine Stress relieve loptional) Finish machine Preheat Austenitize Quench Stabilize (optional) Temper/double temper Final grind
AlO: Tempering Temperature vs Dimensional Change. Dimensional changes by tempering A10 (a) after air cooling from 790 “C (1455 “F) and (b) 925 “C (1695 “F). Changes greater after quenching from 925 “C (1695 “F) due to large amounts of retained austenite. Specimen: 19.05 mm (0.750 in.) diam, 102 mm (4 in.) long
Tool Steels / 559
AlO: Hardness Temperature
and Retained
Austenite
vs Austenitizing
AlO: Isothermal Transformation Diagram. Composition: 1.36 C, 1.84 Mn. 1.14 Si. 1.81 Ni, 0.15 Cr, 1.41 MO, 0.38 graphite. Austenitized at temperatures listed
High-Carbon, Cold
Work
High-Chromium
Tool Steels
(D Series)
Introduction The high-cabon. high-chromium cold \rork 1001 steels. identified t-r> the letter “D”. xc characterized tw carbon contents rnnfmp from I.5 to 2.35Pr carbon and ;1 nommnl chran~um content of 1% The steels contuininp molybdenum cnn be air hxdcned. u hils the molyhdenunt-free mde (D3) is hardened h> quenching in oil. It is not recommended that D serves sreels be normalized. Gsnsrnll~ these steels are supplied m the nnnenlrd condition. hut the! should he annealed after forging and prior to rrhardenin~. Tools that cannot he ground after hxdening xe sometimes stress relieved after rouph machining. especially those that ha\e delicate designs or thnt vrtr~ mwksdl~ in c‘rws section. In many instances. preheating pnor to austsnitizing relieves mnchininp stresses adequately. Preheating prior to xtstenitizinp reduces suhssqusnt distortion in the hardened pxts hv minimizing non-uniform dimensional changes during molten srtlt austenitizinp. The steels ma? hc austenitizsd in nonosidizing baths. in vacuum. or m vrrrtous types of furnaces using gaseous ntmov pheres to avoid dec,uhurtzntion. notably endothemuc atmospheres. do dissociated nmmonia. or dr) hjdrogsn. Ewessivsl) high temperatures
during rlustenitirin@ u ill promote rstninsd austenite nnd should he avoided. To obtain requtred curbids solution for mrxstmum hardness. these steels must he held ;I[ the uustenitirinp temperature for :tt least the recommended period of time The D series tool steels. swept D3. rue quenched in salt or air. Dependinp on section size und other phlsical vtiahles. different methods ma! he rmplo!sd to ohtnm ucselemted coolinp. These methods Include cooline h! quenching m snlt x 540 ‘C r Ic)OO “F) and holding onl! long enouph to squulize temperature throughout all wctions of the tool. by hut in 011 until the steel is or nir hlas~. or oil quenchin, 0 to blnck~usnching helow the temperature rtt which it @o\rs dull red. then cooling to room temperature in air. Tempsrinp is usually begun u hen the steel reaches u temperature of appro\imatsl~ SO to 65 “C i I30 to I50 “F). Double or even triple tempering is commonly smplo~ed to transform retained austenitc. LOU -tsmperstuw stabilizing tr~ntment is optional nnd may incrense hardness rmd impro\s dimsnsmnnl stnhilit\ hy reducing the amount of retninsd austenitc. particularly u hen temperatures ilt the upper end of the nustenilizin~ range rue used.
Chemical Composition.
AISI: Nominal. I .SOC. 12.00Cr. I .OO hlo. 1.00 V. AISI/UNS: Composition: I .-IO to I .60 C. 0.60 Mn ma\. 0.60 Si max. 0.30 Ni max. Il.00 to 13.00 Cr. 0.70 to 1.20 hlo. I.10 V max
Similar Steels (U.S. and/or Foreign). ASThi A68 I t D-2,; FED QQ-T-570 (D-7): SAE 5437 (D?). 1138 tD2): tGer.1 DIN 1.2201. 1.2379. 1.2601: (Fr.) AFNOR MS-590 ?23S Z I60 CDV I?: (Ital.) ClNl X IS0 Crhlo I2 KU: tS\\ed.) SS 2310: tl1.K.~ B.S. 4659 (USA D2). 4659 BD?. 4659 BD?A Characteristics. hlost available and most popular of the D series tool steels. Deep hardening. with low distortion and high safety in hardening. High resistance to softening and medium resistance to drcarhuriring. Readily mtrided Forging.
Preheat IO 650 to 705 “C ( I200 to 1300 “FL Start forging at 1010 to IO95 “C ( 1850 IO 2005 “FL Do not forge after temperature of forging stock drops below 925 “C ( I695 “F). Cool slo~l> after forging Rapid cooling in air from elevated temperatures. such as 915 ‘C ( 1695 ‘FI. is not recommended
Recommended Normalizing. Do
Heat Treating
Practice
not nomlalize
Annealing. Surface protection in thz form of atmospheric gas \rith proper dcu point. nonoGdirinp salt bath. or an inert pack material. such as spent pitch coke. is required to avoid dccarburization. Heat slouly and unifomlly to 870 to 900 “C (I600 to 1650 “FL llse lower limit for small
sec‘nons and upper limit for Inrpe actions. Holding time varies from I I,$ h for light ssctions to 6 h for heal> wctions and lar~r charges: about I t/2 h per inch of thicklie\\ is an adequate npproximntlon to follow. For pack annealing. hold for about I “2 h per inch of cross section of the pack. Cool slowly to 540 “C I I O(KJ “F) at a rate not to exceed 22 “C (-IO “F) per h. after I\ hich a faster cooling rate u ill not affect Final hardness. Typical annealed hardness. 2 I7 to 2% HB
Annealing. Heat to 900 -C I 1650 “F) for 2 h. Slou cool to 77s Cycle “C I l-125 “F) and hold at temperature for -I to 6 h. Cool in air Stress Relieving. Optional. Heat to 675 to 705 ‘C I I245 to I300 “F) and hold for I h per inch of cross section (minimum of I h). Cool in air Hardening. Heat \erJ 40~ I!. Prsheat at 815 “C ( IS00 “F). and austenitlzs at 980 to I025 “C t 179.5 to I875 “F ). Hold at temperature IS min for small tools to 45 nin for large tool>. Quench in air and cool as evenly as possible on all sides. .A block. 76.2 bq 152.1 by 251.0 mm (3 bq 6 h> IO in.) \iill harden throughout to 62 to 61 HRC. M’hen salt quenching, quench in salt bath at S-IO “C t IO00 “F’L hold only long enough to equalize temperature. cool in air Stabilizing. Optional. For intricate shape\ having abrupt changes in section size. stresb relieve temper at I SO to 160 “C (300 to 320 “F) briefly hsfors refrigw-sting at -85 “C (- I20 “FL Temper immediately after part reaches room temperature Tempering. tool has cooled
Temper immediately nt 105 to 5-W ‘C i-l00 to 1000 ‘F, after to about SO to 66 “C ( I20 to I SO “F). Douhle temper.
Tool Steels / 561 allou ing tool Lu cool to room temperature before sscond temper. .\ppro\ima15 tcmpersd hardness. 6 I to S-l HRC
l l l
Recommended
Processing
Sequence
l
l
Rough machine
l
l
Stress rdisw
l
l
Finish machine
copknal~
Prshrat Austrniliz? Quench Stabilize (optional) Tempcr/douhlr [emper Final grind to sizs
D2: Hardness vs Tempering Temperature. Austenitized at 970 “C (1775 “F) and 995 “C (1825 “F) then air quenched. Source: Universal-Cyclops
D2: Hardness vs Tempering Temperature. Composition: 1.50 C and 12.00 Cr; pack hardened at 1010 “C (1850 “F) and cooled in air. Source: Bethlehem Steel
D2: Tempering Temperature vs Dimensional Change. Swedish grade austenitized at two different temperatures. Dimensional change for a similar steel austenitized at a slightly lower temperature. Source: Uddeholm and Carpenter Steel
02: Austenitizing Temperature vs Retained Austenite. position:1.60C.0.33Mn,0.018P.0.010S,0.32Si.11.95Cr.0.79 MO. 0.25 V, when quenched in lime, air and oil
Com-
562 / Heat Treaters
Guide
D2: As-Quenched Hardness. Effect of quenching medium and austenitizing temperature on as-quenched hardness of a D2 tool steel containing 1.50 C
D2: Tempering Transformation Curves for Retained Austenite. Composition: 1.60 C. 0.33 Mn, 0.016 P, 0.010 S, 0.32 Si. 11.95 Cr, 0.79 MO, 0.25 V, air cooled from 980 “C (1795 “F)
D2: Isothermal Transformation Diagram. Composition: 1.50 C. 11.50 Cr, 0.80 MO, 0.20 V. Austenitized at 980 “C (1795 “F). Source: Crucible Steel
D2: Typical Size Changes in Hardening. Changes in length (in inches per inch of original length) of properly hardened and tempered 25 mm (1 in.) round, air quenched from 1010 “C (1850 “F), tempered 1 h at indicated temperature. Source: Carpenter Technology Corporation
Tool Steels / 563
D2: Hardness vs Tempering Temperature. (a) Air cooled. (b) Oil quenched at austenitizing temperatures shown. Specimen size, 25.4 mm (1 in.) cube
564 / Heat Treaters
Guide
D2: Microstructures. (a) 2% nital. 500x. Austenitized at 1010 “C (1850 “F). Air cooled (not tempered). Massive alloy carbide and small spheroidal carbide particles within grains In a matnx of untempered martensite. Hardness, 64 HRC. (b) 2% nital. 1000x. Same steel and heat treatment as (a), except shown at a higher magnification. Hardness, 64 HRC. Some retained austenite is present. but it is not resolved with the etch and magnification used. (c) 2% nital. 500x. Austenitized at 1010 “C (1850 “F), air cooled, tempered at 480 “C (895 “F) for 1 h. Note chromium carbide particles (white) in a matrix of tempered martensite. Grain boundaries are evident. (d) Nital. 100x. Preheated at 790 “C (1455 “F), austenitized at 1010 “C (1850 “F), air cooled. double tempered (2 h plus 2 h) at 540 “C (1000 “F). Magnification too low for good resolution of microconstituents. (e) Nital. 1000x. Same steel and heat treatment as (d). except shown at a higher magnification. Carbide particles rn a matrix of tempered martensrte. Martensite appears dark because of high tempering temperature of 540 “C (1000 “F)
D2: Resulfurized and Cast Tool Steel Microstructures. (a) 3% nital, 1000x. cooled, tempered at 205 “C (400 “F). Hardness, 59.5 HRC. Carbide particles clusions. (b) 39,; nital. 1000x. Same steel as (a). austenitized at 1010 “C (1850 “F). Hardness, 57.5 HRC. Carbide and sulfide particles in a matnx of tempered
Resulfurized (0.100 S), austenitized at 1010 “C (1850 “F), air in a matrix of tempered martensite. Black dots are sulfide in“F). air cooled. double tempered (2 h plus 2 h) at 510 “C (950 martensite
(continued)
Tool Steels / 565
D2: Resulfurized and Cast Tool Steel Microstructures (continued). (c) 3% nital, 1000x. Same steel as (a), austenitized at 870 “C (1600 “F), air cooled, double tempered (2 h plus 2 h) at 510 “C (950 “F). Hardness, 47 HRC. Greater number of undissolved carbide particles indicate underheating. (d) 3% nital, 1000x. Same steel as (a), austenitized at 1120 “C (2050 “F), air cooled, double tempered (2 h plus 2 h) at 510 “C (950 “F). Hardness. 50 HRC. Excessive amount of retained austenite caused by high austenitizing temperature
02: Grain Size vs Prequenching. Effect of austenitizing temperature on grain size after prequenching from indicated temperatures. Prequenching from 980 “C (1795 “F) and below results in significant grain refinement on subsequent hardening. Source: Teledyne VASCO
D2: isothermal Transformation Diagram. Swedish austenitized at 1050 “C (1920 “F). Source: Stora Steels
grade
566 / Heat Treaters
Guide
Nominal. 2.25 C.12.00 Cr. Chemical Composition. AM: AISI/UNS: Composition: 2.00 to 2.3s C. 0.60 Mn mity, 0.60 Si max. 0.30 Ni max. II.00 to 13.50 Cr. 1.00 V max. I .OO W max
Similar
Steels (U.S. and/or Foreign). ASTM ~68 I (D-3); FED QQ-T-570 (D-3); SAE J-137 (D3). 5438 (D3); (Ger.) DIN 1.2080. 1.2136. 1.2883; (Fr.) AFNOR A3S-590 2233 Z 300 C I?: (Ital.) UN1 X 210 Cr I3 KU: (Jap.) JIS G-l404 SKD I, G44O-l SKD 2: (U.K.) B.S. 1659 BD3
Characteristics. Oil quenched. Not as deep hardening as D3. and large sections display greater dimensional change. Nevertheless. is rated as deep hardening, relatively low in distortion. with high resistance to softening at elevated temperatures and medium resistance to decarburization Forging.
Preheat to 650 to 705 “C I I200 to I IfIn “FI Prnrr foginp 1010 to 1095 “C ( I850 to 2005 “F). Do not forge after temperature forging stock drops below 925 “C (1695 “F)
Recommended Normalizing.
Heat Treating
at of
Practice
Hardening. Heat veq slowly. Preheat at 8 I5 “C ( I500 “F), and austenitire at 925 to 980 “C ( I700 to 1795 “F). Hold at temperature I5 min for small tools to 45 min for large tools. Quench in warm oil. Approximate quenched hardness. 6-I to 66 HRC Stabilizing.
Optional. Low-temperature treatment ma): increase hardness and improve dimensional stability by reducing the amount of retained austenite. particularly when temperatures at the upper end of the austenitizmg range are used. For intricate shapes having abrupt changes in section size. it is safer and definitely recommended to stress relieve temper at IS0 to I60 “C (300 to 320 “F) briefly. Refrigerate at -85 “C (- I30 “F). Temper immediately after part reaches room temperature
Tempering.
Temper immediately at 205 to 411) “C (400 to 1000°F) titer tool has cooled to approximately SO to 66 “C ( I20 to I50 “F). Double temper allowing tool to cool to room temperature before second temper. Approximate tempered hardness. 61 to 5-l HRC
Recommended
Do not normalize
l
Annealing.
Protection against decarburiration. Heat slowly and uniformly to 870 to 900 “C (1600 to 1650 OF). Use lower limit for small sections and upper limit for large sections. Holding time varies from I I/, h for light sections to 6 h for heavy sections and large charges: about I ‘12 h per inch of thickness is an adequate approximation to follow. For pack annealing. hold for about I t/2 h per inch of cross section of the pack. Cool slowly to 530 “C ( 1000 “F) at a rate not to exceed 22 “C (30 “F) per h, after which a faster cooling rate will not affect final hardness. Typical annealed hardness. 2 I7 to 255 HB
l l l l l l l l
Processing
Sequence
Rough machine Stress relieve toptlonal) Finish machine Preheat Austenitize Quench Stabilize (optional) Temper/double temper Final grind to size
Annealing. Heat to 900 “C ( I650 “F) for 2 h. Slou cool to 775 cycle “C (I425 “F) and hold at temperature for 4 to 6 h. Cool in air Stress Relieving. Optional. Heat to 675 to 705 “C ( 12-0 to I300 “F) and hold for I h per inch of cross section (minimum of I h). Cool in au
D3: Hardness vs Tempering Temperature. Austenitized “C (1795 “F) and 955 “C (1750 “F), quenched versal-Cyclops
in oil. Source:
at 980 Uni-
D3: Isothermal Transformation “C (1775 “F). Source:
Carpenter
Diagram. Austenitized Technology
Corporation
at 970
Tool Steels / 567
03: Comparison of Tempering Characteristics. D2 and D3 tool steels quenched from several austenitizing temperatures. Steels were austenitized in an air furnace. A recirculating pit-type furnace was used for tempering. Curves represent steel from three suppliers: an average of five hardness measurements made on each specimen from each supplier. Specimens were 25.4 mm (1 in.) diam, and 38.1 mm (1 !I2 in.) long
D3: Chromium Content of Precipitated Carbide vs Hardness. D3 matrix and composition after austenitizing at 950 “C (1740 “F). Steel contained 0.59 C, 0.56 Mn, 0.47 Si, 4.73 Cr. Tempering time, lh
D3: Forging Reduction vs Dimensional Change After Hardening. Composition: 2.0 C. 0.30 Mn, 0.40 Si, 12.0 Cr. Cylindrical specimens, 20 mm (.8 in.) diam by 100 mm (4 in.) long. Bands represent the range of values obtained in specimens cut from square and round bars that had been given various amounts of forging reduction. Orientation of specimens with respect to the forged bars is indicated on the graph
566 / Heat Treaters
Guide
D3: Size Changes in Hardening. Specimens 25.4 mm (1 in.) diam, oil quenched from 970 “C (1775 “F) and tempered 1 h at temperature. Note: tool steels hold size best when quenched from proper hardening temperature. If overheated, they tend to shrink aftertempenng. Source: Carpenter Technology Corporation
D3: Isothermal Transformation Diagram. Swedish austenitized at 1000 “C (1830 “F). Source: Stora Steels
grade
D3: Tempering Characteristics vs Dimensional Change. Swedish grade austenitized at temperatures shown. Source: Uddeholm Steels
568 / Heat Treaters Guide
D4 Chemical Composition. AISI: Nominal. 2.25 C.I 2.00 Cr. I .OO MY. AlSI/UNS: Composition: 2.05 to L-t0 C. 0.60 hln max. 0.60 Si nuts. 0.30 Ni max. I1 .OO to 13.W Cr. 0.70 to I.20 hlo. I .OO \’ ma\ Similar Steels (U.S. and/or Foreign).
air-hardeninp D series. High wfst! in hardening with high resistance to softsninp at elevated temperatures. ~ledium resistance tcl decarhurization
Forging.
Pwhrat to 650 to 705 ‘C t I200 to I300 ‘Ft. Start forging at 1010 to IO95 “C t I850 to 2005 “Ft. Do not forge atkr temperature of forpmg itocb drops hslo\r 925 ‘C ( I695 “F)
Recommended Normalizing.
Heat Treating
Practice
Do not normslir~
Annealing. Surfasrt protection in the form of rndothcmtic atmospheric pas \iith proper dew point. nonosidizing molten salt bath. or an inert pack material. such as sptnt pitch wk. is required to avoid decarhurizntion.
Tool Steels / 569 Heat slou ly and uniformI) to 870 to 900 ;C t 1600 to I650 “F). list lower limit for small sections and upper limit for large sections Holding time vanes from Iti h for light sections to 6 h for heat y sections and large charges: ahout I t/2 h per inch of thickness is an adequav approximation to follo\~. For pack annealing. hold for about I !+ h per inch of cross section of ths pasb Cool 4ou Iy t; S-IO “C ( IO00 “F, at R rate not to cwxd 22 -C (-IO “F) per h. atier N hich 3 faster cooling rate u ill not affect final hardntss. TlpicA annenkd hardness. 2 I7 to 255 HB Cycle Annealing. Heat to 900 “C I 1650 ‘:‘F, for 2 h. Slow cool to 77S “C (I-ES “F) and hold at temperature for -1 to 6 h. Cool in air !%eSS Relieving. Optional. Heat to h7.i to 705 “C t I?45 to I.300 “Ft and hold for I h per inch of cross section (minimum of I h,. Cool in air
Hardening.
Heat \rr> SIOWly. Preheat at 8 IS -‘C ( I SO0 “F,. and austenitire at 970 to 1010 “C t, 1775 to I850 “FI. Hold at tempsraturz I5 min for small tools to -15 min for large tools. Quench in air and cool as evenly as possihlc on all sides. particularly on long tlat dies. Approximate quenched hardness. 6-l to 66 HRC.
nustenite. particulsrl~ when temperatures at the upper end of the austenitizing rfn!e are used. For intricate shapes having abrupt changes in section size. tt IS safer and definiteI! rzcommended to stress relieve temper at 150 to I60 “C t.100 to 320 “Fi brisfl~. Rsfrigeratc at -85 ‘C t-120 “F). Temper immediately after part rsachss room tsmperature
Tempering.
Ttmpsr immediateI\ at ‘OS to S-IO ‘C (400 to 1000 “F) after tool has cooled to npprosimntcly -SO to 66 “C t I20 to IS0 “F). Double temper. alloying tool to cool to room temperature before second temper. Approximate tempered hardness. S-I to 61 HRC
Recommended l l l l l l l
Stabilizing.
l
ness
l
Optional. Len-temperature treatment ma) increase hardand improve dimenk~nal stability b> reducing the amount of retained
Processing
Sequence
Rough machine Stress relieve toptionnl~ Finish machine Preheat Austrnitiz2 Quench Stabilize (optional 1 Temper/double temper Final grind to size
D4: Isothermal Transformation Diagram. Composition: 2.25 C, 11.50 Cr, 0.80 MO, 0.20 V. Austenitized at 980 “C (1795 “F). Source: Crucible Steel
570 / Heat Treaters
Guide
D4: Isothermal Transformation “C (1795 “F)
Diagram. Austenitized
at 980
D4: Hardness vs Tempering Temperature. Austenitized
at 970
“C (1775 “F) and 1035 “C (1895 “F), and cooled in air
D4: Hardness vs Tempering Temperature. Tempering curves for D4 tool steel containing 2.17 C, 11.68 Cr. 0.78 V, 0.51 Co. Austenitized at the five temperatures shown, cooled in air, and tempered for 1 h at the tempering temperature. Source: Teledyne VASCO
570 / Heat Treaters
Guide
D5 Chemical
COfIIpOSitiOn. AISI: Nominal. I .SO C. 12.00 Cr. I 00 hlo. 3.00 Co. AISl/UNS: Composition: I .-IO IO I .60 C. 0.60 hln max. 0.60 Si max. 0.30 Ni max. I I .OO to l3.OOCr. 0.70 to 1.20 MO, I .OO c’ max. 2.50 to
3.50 co
Similar
Steels (U.S. and/or Foreign).
QQ-T-570 (D-S); AFNOR A35-90
ASTM SAE 1437 (D5). 5438 (DS); (Ger.) 2236 Z 160 CKDV 12.03
~68 I (D-S); FED DfN 1.2880: tFr.)
Characteristics. Very similar to D?. except it does not contain vanadium and 3% cobalt is added to impan resistance to softening at elevated temperature. As H ith other grades of the D series, it is deep hardening and veq low in distortion. having very high wear resistance and medium decarburizarion resistance
Tool Steels / 571
Forging.
Preheat to 650 to 705 “C ( I200 to I300 “Fi. Start forging at IO IO to 1095 ‘C ( I850 to 2005 “F). Do not forge after temperature of forging stock drops below 935 “C ( 1695 “F). Slow cool after forging
Recommended Normalizing.
Heat Treating
Practice
Do not normalize
Annealing. Surface protection in the form of endothermic atmospheric gas with proper dew potnt. nonoxidizing molten salt bath. or an inert pack material. such as spent pitch coke. is required to avoid decarburiration. Heat slowly and uniformly to 870 to 900 “C ( I600 to I650 “FI. Use loher limit for small sections and upper limit for large sections. Holding time varies from I t/4 h for light sections to 6 h for heavy sections and large charges; about I l/z h per inch of thickness is an adequate approximation to follow. For pack annealing, hold for about I t/z h per inch of cross section of the pack. Cool slowly to 540 “C ( 1000 “F) at a rate not to exceed 22 “C t-10 “F) per h, after which a faster cooling rate M ill not affect final hardness. Typical annealed hardness. 2 I7 to 255 HB
tools to -IS min for large tools. Quench in air and cool as evenly as possible on all sides. Approsimate quenched hardness, 61 to 64 HRC
Stabilizing.
Optional. Low-temperature treatment may increase hardness and improve dimensional stability by reducing the amount of retained austenite. particularly u hen temperatures at the upper end of the austenitizing range are used. For intricate shapes having abrupt changes in section size. it is safer and definitely recommended to stress relieve temper at I50 to 160 “C (300 to 330 “F) briefly. Refrigerate at -85 “C (-I 20 “F). Temper immediately after part reaches room temperature
Tempering.
Temper immediately at 205 to 540 “C (400 to 1000 “F) after tool has cooled to approximately SO to 66 “C (120 to I50 “F). Double temper. allowing tool to cool to room temperature before second temper. Approximate tempered hardness. 5-I to 61 HRC
Recommended l l
Cycle Annealing. Heat to 900 “C (I650 “F) for 2 h. Slou cool to 775 “C (I435 “F) and hold at temperature for -I to 6 h. Cool in air
Stress Relieving.
Optional. Heat to 675 to 705 “C ( 13X to I300 “FI and hold for I h per inch of cross section (minimum of I h). Cool in air
l l l l l
Hardening.
Heat slowly. Preheat at 8 IS “C t IS00 “F). and austenitize at 980 to 102.5 “C (I795 to 187s “F). Hold at temperature IS min for small
D5: Tempering Austenitized
Characteristics
vs Dimensional
at 1010 “C (1850 “F) and quenched
in air
Change.
l l
Processing
Sequence
Rough machine Stress relieve (optional) Finish machine Preheat Austenitize Quench Stabilize (optional) Temper/double temper Final grind to size
D5: Effect of Tempering Temperature on Dimensional Change. 0. D3 austenitized at 955 “C (1750 “F) and quenched in oil. 0, D5 austenitized at 1010 “C (1850 “F) and cooled in air. A, D2 cooled in air. Specimen, 25.4 by 50.8 by 152.4 mm (1 by 2 by 6 in.). Source: Latrobe Steel
572 / Heat Treaters
Guide
D7 Chemical Composition. AISI: Nominal. 2.X C. I XXJ Cr. I .(X1 hlo. -1.00 V. AlSI/UNS: Composition: I IO to 1.30 C. 1.00 hln ma\. 0.60 Si nix. 0.30 Ni m;L\. 0.35 to 0.X5 Cr. 0.30 hlo max. O.-IO L’ m;\s. I .OOto XMJ M Similar
Steels (U.S. and/or Foreign).
QQ-T-570 (D-7); SAE J-I37 iD7j. AFNOR 2737 Z ‘30 CVA 12.0-l
.4SThl J-l.38 tD7~: tGer.j
,-16X1 (D-7); DIN 1X78:
FED tFr.j
Characteristics. Requires slight11 hipher tempemture lmd lonccr time to dissolve carhides u hen austenitiring thnn others In D series. Deep hxdening and relntivel> IOU distortion. Hti high resistance to softening ;It elevated temperatures. and medium decarhuriration resistunce Forging.
Preheat to 6SO to 705 “C t I200 to I300 “F). Starr forging nt II20 to I I65 “C t?O50 to 2125 ‘FI. Do not forgs ufter temperaturs of forging stock drops below 980 ‘C I I795 “FI
Recommended Normalizing.
Heat Treating
Heat blo\\ I!. Preheat 318 I 5 “C I I.iOO “‘FJ. and austenitlze at IO IO to 1065 “C I I850 to I950 “FJ. Hold ;tt temperature 30 tin for small tools to I h for Ixgs tools. Quench in air und cool as evenly BS possihlr on all Gdcs .\pproxmlxe quenched hrudness 63 to 66 HRC
Stabilizing.
Optionul. Lou -tzmpsrsturs tre;ltment may increase hardnebs and impro\c dimrnsionul reducmp the amount of retamed nustsnite. p;uIIcuI~rI! u hen temper:wres at the upper end of the nustenitizlnp ranpz ;lrt wed. For Intricate shape> hating abrupt changes in sectwn size. It IS safer and definiteI\ recommended to stress relir\e temper ;It I SO to I60 “‘C t?OO to 330 ‘F) bhetlj. Refripsrnte ;It -X5 “C t-l 20 “F). Temper 1mmedi3tel> atier pxt reaches rocm tempemture Temper immsdintel\ ;1t 150 to 540 “C (300 to I (Jo0 “FJ after tool ha5 pooled to ~ppro\lmntel> 30 to 66 “C t 120 to IS0 “F,. Double temper. allo\\ inp tool to cool to room temperature before second temper. ,.Ipppro\Imate tempered hwdtwss. 5X IO 65 HRC
Annealing.
Surface protection in the foml of atmospheric g;~b u ith proper dew point. nonolidizing molten b;IIt bath. or an inert pnsh mutsrial. such as spent pitch coke. is required. Heat slo\r Iy and uniformI> 10 li70 to 900 “C t IhOtJ to 1650’-‘Fj. llse lower limit for mall sections and upper limit for large sections. Holding time \ tics from I ’ i h ft>r light section5 to 6 h for hew> sections and lugs chlv_ees: about I ’ 2 h per inch of thicknssb 13 nn adequate approlimatlon to folio\\. For path anne~lin_g. hold for nhout l ‘/! h per inch of cross section of the pack. Cool slot\ 1) to SKY “C I ItJOt) ‘Ft at il mte not to exceed 22 “C (10 ‘FI per h. uftcr u hich il faster coolinp rute u ill not afkct final hardnesb. Typicul arms&d hardness. 2 I7 10 255 HB
Annealing. Hent IO 900 ‘C t 1650 “F) for ? h. Slo\r cooI to 775 Cycle “C t I-l?_i “FJ and hold at temperature for 1 to 6 h Cool in air
Temperature vs As-Quenched
Hardening.
Tempering.
Practice
Do not normalize
D7: Austenitizing
Stress Relieving. Optlon;ll. Hsut to 675 to 705 ‘C t 1% to 1300 ‘F) and hold for I h per Inch of cross section (minimum of I h). Cool in ;1Ir
Hardness.
Composition: 2.30 C, 0.40 Mn, 0.40 Si. 12.50 Cr. 1 .lO MO. 4.00 V and air quenched
Recommended
Processing
Sequence
Roush machine Strew relis\ 5 (optional 1 l Fit&h mnshins l Preheat l .4ustsnitize . Quench l Stabilize (optional, l Temper/double temper l Finn1 yind to size l l
D7: Tempering
Characteristics
and Dimensional
Change.
Austenitized at 1035 “C (1895 OF) and air quenched. Dimensional change for the same steel austenitized at 925 “C (1695 “F) and air quenched
Tool Steels / 573
D7: Microstructures. (a) Nital, 100x. Preheated ‘,$ h at 815 “C (1500 “F), austenitized at 1080 “C (1975 “F), and air cooled. Not tempered. See (b) for better resolution of structure. (b) Nital. 500x. Same steel and heat treatment as (a), except higher magnification. Small spheroidal particles of carbide resolved. Massive complex alloy carbide provides abrasion resistance. Matrix is martensite. (c) 4% nital, 1000x. Austenitized at 1040 “C (1905 “F). air cooled, and tempered at 540 “C (1000 “F). 61 HRC. Structure of small and massive carbide particles (white) in a matrix of tempered martensite. (d) Nital. 100x. Preheated at 615 “C (1500 “F). austenitized at 1080 “C (1975 “F), air cooled, and tempered at 175 “C (345 “F) for 2 h. Structure carbide particles in tempered martensite. See (e) and (f) for better resolutions. (e) Nital, 500x. Same steel and heat treatment as (d), except shown at higher magnification. Austenitizing temperature high. Matrix contains considerable unetched retained austenite. (f) Nital, 1000x. Same steel and heat treatment as (d), except shown at still higher magnification. Most of the small carbide particles have dissolved because of high austenitizing temperature, but massive carbide remains
Low-Alloy
Special-Purpose
Tool Steels
(L Series)
Introduction The L series 1001 steels are essentially similar in composition to the water-hardening tool steels. except that the addition of chromium and other elements provides these steels with greater wear resistance and hardenability. Type L2. for example, is similar to the bearing steel 52100 except for carbon content. Because of their relatively low austenitizing temperatures. L steels are easily heat treated. The L steels should be normalized following forging or when otherwise subjected to temperatures above their austenitiring temperatures. For these steels. normalizing consists of through heating to 870 to 900 “C ( 1600 to 1650 “F) and cooling in still air. Using a protective atmosphere is recommended if all surfaces will not be removed by machining. Annealing must follow normalizing and precede any rehardenmg operation. The recommended annealing temperature. cooling rates, and expected as-annealed hardness values are given below for the individual steels covered in this section. To minimize distortion during hardening. stress relieving prior to hardening may be advantageous for complex tools. One common practice
for complex tools is IO rough machine. heat to 620 to 650 “C (I I SO to I200 OF) for I h per inch of cross section. cool in air. and finish machine prior to hardening. The L steels seldom require preheating prior to austenitizing. Salt baths and atmosphere furnaces are satisfactory for austenitizing these steels. A neutral salt bath. such as a mixture containing 70% barium chloride and 3OC, sodium chloride. is recommended. This salt may be deoxidized by means of rectification for control of decarburization. Oil is the quenching medium most commonly used for L steels. Water or brine may be used for simple shapes or for large sections that do not attain full hardness by oil quenching. Rolling-mill rolls are pans for which water or brine quenching is used. L steels respond well to martempering. The L steels should be withdrawn from the quenching medium at approximately 52 IO 82 “C (125 to 180 “F) and should be tempered immediately thereafter. or cracking may occur. Tempering these low-alloy steels at a minimum of I20 “C (250 “F) is recommended, even if maximum hardness is desired. Double tempering is also recommended.
L2 Chemical Composition. AISI: Nominal. 0.50 to I. IO C (wious carbon contents are available), 1.00 Cr. 0.20 V. AISI/UNS (T61202): Composition: O.-IS to 1.00 C. 0.10 to 0.90 hln. 0.50 Si max. 0.70 to 1.20 Cr. 0.25 hlo max. 0. IO to 30 V Similar Steels (U.S. and/or Foreign). ASTM ~681 (~-2): FED QQ-T-570 (L-2); (Ger.) DIN 1.2235. I.2211. I .2X2. I.22-!3: (Fr.) AFNOR A3S-590 3335 55 CNDV 4: (Jap.) JIS G-t-W SKT 3 Characteristics.
A general-purpose steel containing I Cr,chromium for hardenability and wear resistance, and 0.204 vanadium for gram refinement. Available in a range of carbon contents from 0.50 to l.lOQ. Is considered to be similar to several alloy constructional steels. depending on carbon content. Has high safety in hardening. medium depth of hardening and distortion in heat treating. low to medium bear resistance. high machinability and resistance to decarburization
Forging. Start forging at 980 to I095 “C ( I795 to 2005 “F). Do not forge belou 8-t_’ “C ( 1555 “F)
Recommended
Heat Treating
Practice
Normalizing. Heat to 870 to 900 “C ( I600 to 1650 “F). Holding time. after uniform through heating. varies horn approximately I5 nlin for small sections to approximately I h for large sections. Work is cooled from temperature in still air
Annealing.
Atmosphere protection against decarburization or carburization is required unless all surfaces are to be removed by machining before final heat treatment and use. Heat to 760 to 790 “C (I400 to I155 “F). Use lower limit for small sections and upper limit for large sections. Holding time vanes from approximately I h for light sections and small furnace charges. to approximately -I h for heavy sections and large charges. For pack annealing. hold for I h per inch of cross section. Cool slowly to St0 “C ( 1000 OF) at a rate not to esceed 22 “C (-10 “F) per h. after which faster cooling will not affect tinal hardness. Typical annealed hardness. 163 to 197 HB
Stress Relieving. Optional. Heat to 650 to 675 “C ( 1200 to I235 “F) and hold for I h per inch of cross section. Cool in air Hardening. Use protective media such as endothemlic gas (use dew point of IO to I3 “C. or SO to 45 “F. for O.SOQ, carbon and 2 to 1 “C. or 35 to -IO “F. for I.005 carbon), molten salt, pack, or vacuum to prevent decarburization or carbunzation. Heat slovrly (particularly intricate tools). Austenitize at 815 to 925 “C i IS55 to 1695 “F) for oil quenching, and 790 to 815 “C (1-M to IS55 “F) for water quenching. The latter may be used uncomplicated, and have no sharp for large sections that x2 symmetrical. stress raisers. Honever. cool no louer than 60 “C (I10 “F) and temper immediately. Time at austenitizinp temperature varies from approximately IO mitt for small sections to approximately 30 min for large sections. Quench in u arm. agitated oil to approximately 52 “C (I 25 “F). and place immediately in tempering furnace. As-quenched hardness. 5-I to 61 HRC
Tool Steels / 575 Tempering. inp approximate
Temper at I75 to 530 “C (US to 1000 “F) for a correspondtempered hardness of 63 to 45 HRC
l l l
Recommended l l
Processing
Sequence
Nomlalize Rough machine
l l l
Stress relieve (optional) Finish machine Austenitire Quench Temper Final grind to size
L2: Isothermal Transformation Diagram. Specialpurpose tool steel containing 0.45 C, 0.70 Mn, 1 .OOCr, 0.20 V. Austenitizing temperature: 900 “C (1650 “F). Source: Crucible Steel
L2: Jominy End-Quench Teledyne VASCO
Hardenability.
Special-purpose
tool steel containing
0.50 C, 0.80 Cr, 0.20 V. after austenitizing.
Source:
L2: Jominy
End-Quench
Hardenability.
Composition:
0.60 C. 0.80 Cr, 0.20 V after austenitizing.
L2: Austenitizing Temperature vs As-Quenched Hardness. Special-purpose tool steel containing 0.45 C, 0.55 Mn, 0.95 Cr. 0.20 V. Source: Bethlehem Steel
Source: Teledyne VASCO
L2: Tempering Temperature vs Hardness. Effect of tempering and austenitizing temperature. and quenching medium on hardness of special-purpose tool steel. Source: Universal-Cyclops
576 / Heat Treaters
Guide
L6 Chemical COftIpOSitiOn. AH: Nominal. 0.70 C. I._50 Ni. 0.75 Cr. 0.75 MO toptional). AISI/UNS (T61206): Composition: 0.65 IO 0.75 C. 0.3 IO 0.80 Mn. 0.50 Si max. I.15 to 2.00 Ni. 0.60 to I.20 Cr. 0.50 hlo max. 0.70 to 30 V loptional) Similar QQ-T-570
Steels (U.S. and/or (L-6):
Foreign). r\SThl ~681 (L-6): FED SAE 1437 tL6). J-138 (Lh); Gzr.) DIN I .27 I?. I .27 I-I:
1Fr.j AFNOR SKT-II
A355903381
55 NCD\‘7:tJap.)
J1SG-M-l
SKS SI.G4-l04
Characteristics. .A prnrml-put-pow st.4 cnpahle of hardening to as high as 62 HRC. Compo4tion similar IO that of the popular 4340 all+ grads. hut contains 0.705 carbon. Available M ith .weral molj hdenum contents: additional amounts of mol> hdenum incrsase the depth oC hard-
Tool Steels / 577 ness. which IS generally classified as medium. Has ION distortion m heat treating. high safet, in hardening. and high resistance IO decarhuriration
Forging. Start forging at 980 to 1095 “C ( I795 to 2000 “FL Stop forging at X-15 ‘C I IS55 “F)
Recommended
Heat Treating
Practice
Normalizing. Heat to 870 “C I 1600 ‘FL Holding time. after uniform through heating. \ aries from approsimatel> IS min for small sections to appro\:imatel> I h for large vxtlons. LVork is cooled from temperature in htill air Annealing.
.Atmosphsre protection apalnst decarhutizatlon or carburlzatwn is required unless all surfaces are to he removed h> machinmg hsfore final heat treatment and use. Heat to 760 to 790 ‘C t I-400 to 1455 ‘FL llse lwer limit for small sections and upper limit for large bections Holding time varies from approxlmatsl>: I h for light bsctions and small furnace charge>. to approximately 4 h for hea\>- sectIons and large charge? For pack. annealing. hold for I h per inch ot cross section of container. Cool slo\r I! IO S-10 “C I I000 “FI at a rate not to esseed 21 “C 140 ‘Fj per h. atier M hich faster cooling will not affect final hardness. Typical annealed hardnest. I X3 IO 255 HB Optional. Heat to 650 to 675 “C t I200 to IX and hold for I h per inch of cross section. Cool in air stress
Relieving.
L6: Isothermal Transformation temperature:
Diagram. Special-purpose 845 “C (1555 “F). Source: Crucible Steel
‘FI
Hardening. Use protectke media such as endothermic gas (use dew point of I3 to I8 “C. or 5.5 to 6S “FL molten salt. pack. or vacuum to prevent decarhurization or carhurization. Heat slowly (particularly inuicate tools). Austenitlze at 790 to 815 “C t 1155 to IS55 “F) for IO to 30 min and quench m \\urm. agitated oil. Thin intrvxte sections can he quenched in an agitated bult bath at approaimately 175 “C (345 ‘F) until tools reach bath temperature Then cool in air. This ma> decrease quenched hardness by an HRC point or two. hut \
Temper at I75 IO S40 “C t 3-U to 1000 “F) for a correspondtempered hardness of 62. to 15 HRC
Recommended l l l l l l l l
Processing
Sequence
Normalizs Rough machine Stress relic\ 5 toptional) Finkh machine .Au+xitize Quench Temper Final grind to 51ze
tool steel, containing 0.75 C, 0.70 Mn. 1.50 Ni. 0.75 Cr. 0.30 MO. Austenitizing
578 / Heat Treaters
Guide
L6: Jominy End-Quench Hardenability. Cr, 0.25 MO. Source: Teledyne VASCO
Hardenability
curves for an L6 special-purpose
tool steel containing 0.70 C, 0.55 Mn, 1.40 Ni, 0.85
L6: Isothermal Transformation Diagram. Special-purpose tool steel, containing 0.72 C, 0.35 Mn, 0.018 P, 0.010 S, 0.23 Si, 1.75 Ni. 0.94 Cr. Austenitizing temperature: 830 “C (1525 “F). Source: Carpenter Steel
L6: Tempering Temperature vs Hardness. Effect of tempering temperature and carbon content on the hardness. Source: Universal-Cyclops
L6: Austenitizing Temperature and Quenchant vs AsQuenched Hardness. Effect of austenitizing temperature and quenching medium on the as-quenched hardness of a 25 mm (1 in.) diam by 125 mm (5 in.) specimen containing 0.75 C. 0.75 Mn, 1.75 Ni, 0.90 Cr. 0.35 MO. Source: Bethlehem Steel
L6: Dimensional Change vs Tempering Temperature. Effect of tempering temperature on dimensional change of special-purpose tool steel. Source: Carpenter Steel
Tool Steels / 579
L6: Size Change in Hardening. Bar 25 mm (1 in.) in diam was oil quenched from 830 “C (1525 “F) and tempered 1 h at indicated temperatures. Source: Carpenter Technology Corporation
L6: Length Change as a Function of Tempering Temperature. A 19 mm @4 in.) round specimen of an L6 special-purpose tool steel containing 0.75 C, 0.35 Mn, 1.75 Ni, 1 .OOCr
L6: Jominy Hardenability. Austenitized at 845 “C (1555 “F). Source: Carpenter Technology Corporation
Mold Steels
(P Series)
Introduction The P series steels are unique in that their cnrhon content ranges from vep low to medium and their allo) content from ahout O.Sc”r to il maximum of&out 5%. Depending on composition. Psteels can he used for plastic molds. and. to ;1 lesser estent. for die-casting dies. The hardening process is explained in detail in the paragraphs describing each P steel. P1l is an exception. hardened hy solution treating and agtng. The low-carbon grades ma) he carhurized. nnd the medium-carhon grades are sometimes nltrided.
The annealing of these steels often is neither necessaq nor desirable, hecaube il full\ annealed structure is more difficult to machine. Thz cmhuriring and n&din_p processes used folio\\ the standard practices for other carbon or low-rrllo\ steels. The heat treatment or P series steels closely resembles the p&ices applied to mnny carbon and low-alloy steels and has little similarit! to the methods used N ith the higher alloyed tool steels. espe4l) those with high carbon contents. Details of heat treating the \ arious P steels ;ue co\ cred in the folk>\\ mg pluagraphb.
P2 Chemical COfIIpOSitiOn. AISI: Nominal. 0.07 C. 2.00 Cr. 0.50 Ni. 0.20 Mo. AISI/UNS (T51602): Composition: 0. IO C mas. 0. IO to 0.40 hln.O.IOtoO.-l0Si.O.IOto0.S0 Ni.O.75 to 1.2SCr.O.lS toO.40 hlo Similar
Steels (U.S. and/or
Foreign).
ASThI ~68 II P-2)
Characteristics. let-&tics. buririnp. obtained depth of softening
A lo\\-carbon grade with good hohhmp chwacContains chromium and molj bdenum for hardenability after carand nickel to improLe core strength. Full hardness is usually by oil quenching which minimizes distortion. Rated medium in hardening, low in distortion in heat treating IOU in resistance to at elevated temperature. and high in resistance to decarburization
22 ‘C 110 ‘-FI per h. The maximum rate ts not critical after cooling S-IO “C t IO00 :‘F,. T! picat annealed hardness. I03 to 11-3 HB
to helo~
Stress RelieVing. Optional. Heat to 650 to 675 “C ( 1200 to I~-15 “F) and hold for I h per inch of cross section (minimum of I h). Cool in air
Hardening. C,arhurize at 900 depth. Austrnitize at 830 to 845 temperature for IS min one‘s the Quench in wrm. agitated oil or 62 to 65 HRC
to Y’S “C ( IhSO to 1695 ‘FJ to desired case “C t IS?? to IS55 “F). Hold at austenitizing temperature is uniform throughout the tool. in hrine. Approximate quenched hardness.
Tempering.
Start forging at IO IO to I I20 “C I 1850 to 2050 “FL Do not forge below 845 “C ( IS55 “F)
Temper at I75 to 260 ‘C (?-IS to SO0 “F). Approximate hardnes> of the case as it corre>ponds to tempering temperature. 6-l to 58 HRC
Recommended
Recommended
Forging.
Normalizing.
Heat Treating
Practice
Not necessary to normalize
l l
Annealing.
Heat to 730 to 8 IS “C ( I350 to IS00 “FL Cke lower limit for small sections and upper limit for large sections. Holding ttme \aries from approximately I h for light sections and small furnace charges. to approximately 3 h for heavy sections and large charse,. For pack annealing. hold for I h per inch of cross section. Avoid surface carburization. u hich drastically impairs metal flow when hohhing. Cool at a marimum rate of
l l l l l l
Processing
Rough machine Stress relkr toptlonal. Finish machine Carburizr Harden Quench Temper Final grind and polish
hetwesn
Sequence
and after final bobbing)
Tool Steels
P2: Hardness vs Tempering Temperature. Tempered surface hardness of a P2 tool steel (carburized case) carburized at 925 “C (1695 “F) for 8 h and quenched in oil. Source: Crucible Steel
/ 581
P2: Isothermal Transformation Diagram. P2 tool steel with a carburized case, indicating depth hardening characteristics after carburizing. Composition of the steel, which was austenitized at 845”C(1555”F),was0.07Cmax.0.55Ni. 1.35Cr,and0.20Mo. Source: Crucible Steel
Tool Steels / 581
P3 Chemical
COITIpOSitiOII. AM: Nominal. 0. IO C. 0.60 Cr. I.25 Ni. (T51603): Composition: 0. IO C max. 0.20 to 0.60 hln. 0 -IO Si max. I .tHJ to I SO Ni. 0.40 to 0.75 Cr AISl/UNS
Similar
Steels (U.S. and/or
DIN 1.5713:tFr.JAFNOR2881
Foreign).
ASTM
A68I(P-3):
tGer.r
‘1.l0NC6
Characteristics.
Another hohbing grade. alloyed to provide medium hardrnnhilit). a high case hardness. and good surface polishing characteristics. Usually oil quenched. but the carbunring and hardening practice is essentially the same as that for P2. Rates lw in distortton in heat treattry. high in touphness. low in resistance to softeninp at elevated temperature. and high in reststance to decarhunrntion Range of core hardness. IS to 25 HRC
Forging. forge belo\\
Start forging at 1010 tn I I20 “C t It350 to 2050 ‘FJ. Do not 870 “C ( I600 “FJ
Recommended Normalizing. Annealing.
Heat Treating
Practice
Not nscessar~ to normalize
Heat to 730 to 8 IS :C I I350 to I SO0 “FJ. lk IOU er limit for small sections and upper limtt for large secttons. Holding time \ aties from approximateI> I h for light secttons and small furnace charges. to approximatsI> 1 h for hea\) sections and large charges. For pack annealing. hold for I h per inch of cross sectton. Xvoid surface carhunzation. \\hich drasticallq impairs metal flom uhen hohhinp. Cool at a maximum rate of
22 “C t-IO “FJ per h. The maximum rate is not critical aftercooling 540 ‘C I IWO “FJ. T> pica1 annealed hardness. IO9 to I37 HB
to belo*
Stress RelieVifIg. Optional. Heat to 650 to 675 ‘C ( I200 to I235 “F) and hold for I h per inch of crash section tminimum of I h). Cool in air
Hardening. Carhurizs at 900 to 925 ‘C t I650 to 16% “FJ to desired case depth. Harden at 800 to 830 “C t l-175 to 1525 “FJ. Hold at austenitizing temperature for IS min once the tempernrure is uniform throughout the tool. Quench in ~\arm. ~tgorously agitated oil. This grade has the lowest hardenahilit) of the P series mold steels. Approximate quenched hardness. 62 to 64 HRC Tempering.
Temper at I75 to 260 “C (345 to SO0 “F). Approximate tempered case hardness as it corresponds IO tempering temperature. 64 IO S8 HRC
Recommended l l l l l l l l
Processing
Rough machine Stress relieve toptional. Finish machine Carhurize Harden Quench Temper Final grind and polish
bet\rcen
Sequence
and after final hohhing)
Tool Steels / 581
P4 Chemical
Composition. AISI: Nominal. 0.07 C. 5.00 Cr. 0.75 hlo. AISI/Uh’S (T51604): Composition: 0.12 C max. 0.7-O to 0.60 hln. 0. IO to 0.40 Si. 4.00 to 5.25 Cr. 0.10 to I .OO hlo Similar
Steels (U.S. and/or
DIN 1.2341: tS\rrd.)
SS tUS.4 P4)
Foreign).
ASThl
,468 It P-4): tCkr.b
Characteristics. Has the highest hardsnability of the hobbing grades of P tool steels and ran be considered the mold steel equivalent to the medium-alloy cold ~iork die steel A?. Can be air hardened for minimum distortion or oil quenched to avoid surface scaling. Has the highest wear resistance and x&ning resistance at cle\ated temperatures of any of the
582 / Heat Treaters
Guide
mold steels. Rates high in depth of hardening, very low in distortion treating. with high resistance to decarburization
in heat
Recommended
Processing
Rough machine Stress relieve (optional. . Hob l Carburize l Harden l Quench l Stabilize (optional) l Temper l Final grind and polish
Sequence
l
Forging.
Start forging at 1010 to II20 forge below 870 “C ( I600 “F)
Recommended Normalizing.
Heat Treating
“C ( 1850 to 1050 “F). Do not
Practice
Do not normalize
Annealing.
Heat to 870 to 900 ‘C (1600 to 1650 “F). Use lower limit for small sections and upper limit for large sections. Holding time varies from approximately I h for light sections and small furnace charges. to approximately 1 h for heavy sections and large charges. For pack annealing. hold for I h per inch of cross section. Avoid surface carburization, \rhich drastically impairs metal flop when hobbing. Cool at a maximum rate of l-l “C (25 “F) per h. The maxmium rate is not critical after cooling to belob S-MI “C ( 1000 “F). Typical annealed hardness. I I6 to I28 HB
l
P4:
between and after final hobbing operation)
Effect of Tempering
Temperatures
on Hardness
Tempering
Strt?SS RelieVing. Optional. Heat to 650 to 675 “C I I200 to 1265 OF) and hold for I h per inch of cross section (minimum of I h). Cool in air
Hardening. Carburize at 970 to 995 “C ( I775 to I825 “F) to desired case depth. Harden at 970 to 995 “C ( I775 to I825 “F) by holding at temperature for IS min once the temperature is uniform throughout the tool. Quench in air or oil. This grade may also be quenched in hot salt at S-IO to 650 “C ( IO00 to I200 “F) to prevent scaling of cavity. Cool in air as soon as temperature is uniform throughout the tool. Approximate quenched hardness. 62 to 65 HRC
temperature T
OF
Stabilizing. Optional. Low-temperature treatment ma) increase surface hardness. It is safer to stress relieve temper at IS0 to I60 “C (300 to 320 “F) for a short period after refrigerating at -85 “C f-l 70 OF)
4s treated IS0 20s 260 31.5 370 1’5 180 5-Kl 595 650
Tempering.
Jo mm t I 5 in.) round pa&d
Temper at I75 to 480 “C (315 to 895 “F). Approximate surface hardness as it corresponds to tempering temperature. 61 to 58 HRC
P4: Tempering Characteristics-Carburized
Case and Core.
0: P4 carburized in hardwood charcoal at 910 to 925 “C (1675 to 1700 “F) for 8 h, air cooled in pack, reheated at 940 to 955 “C (1725 to 1750 “F), cooled in air, and tempered. 0: P4 carburized in cast iron chips at 940 to 955 “C (1725 to 1750 “F). removed from pack, cooled in air and tempered
I I7SO”Fj.
Case Hardness, HRC
Core Hardness, HRC
s3s-l 501.53 SO/S3 so/s I 49/50 19/50 49/5O SOI5 I -al49 -w-u 32134
36/M 36138 38/39 37138 37138 37/38 38139 3809 39MO 37138 ?I/?’
3w -mo so0 600 700 800 900 IO00 1100 Iml
in neu gray (as1 iron chips . cooled m air from 955 “C
Source: CqrnterTrchnolog~
Corporation
P4: Tempering Temperature vs Carburized Surface Hardness. P4 compared to Wl . Both carburized at 925 “C (1695 “F) for 8 h in charcoal Steel
powder,
and quenched
in oil. Source:
Uddeholm
Tool Steels / 583
P4: Isothermal Transformation
Diagram. P4 containing 0.14 C, 0.41 Mn, 0.21 Si, 0.19 Ni, 5.12 Cr, and 0.51 MO. Austenitized at 900 “C (1650 “F) and quenched in water. As-quenched hardness. 41 HRC
Tool Steels / 583
P5 Chemical
Composition.
AlSI/UNS
AISI:
(T51605): Composition:
Nominal. 0.10 C. 2.25 Cr. 0. IO C max. 0.20 IO 0.60 Mn. 0.40 Si
max. 0.35 Ni max. 2.00 to 2.50 Cr
Similar
Steels (U.S. and/or
Foreign).
ASThl
A68 I( P-S)
22 “C (10 “Fj per h. The maximum rate is not critical after cooling 5-R) “C i IO00 “F). Typical annealed hardness. I05 to I3 I HB
to below
Stress Relieving. Optional. Heat to 650 to 675 “C (I 200 tn I215 “F) and hold for I h per inch of cross section (minimum of I h). Cool in air
Low carbon hot&ring grade \rith enough alloy to impart medium hardenahilit>. Has IOM distortion in heat treating u hen oil quenched. IOM resistance to softening at elevated temperatures. and high resistance to decarhurization
Hardening. C~burizr at 900 to 925 “C t I650 to I695 OF) to desired case depth. Harden at 815 to 870 “C t IS55 tn 1600 “F). Hold at austenitizing temperature for IS mitt once the temperature is uniform throughout the tool. Quench in wrm. agitated oil. Large sections without severe stress raisers can he water quenched with caution if maximum hardness is desired
Forging. Start forging at 1010 to I 120 ‘Y’ t 1850 to 2050 “FJ. Do not forge helow 8-U “C t I555 “F)
Tempering.
Characteristics.
Recommended Normalizing.
Heat Treating
Practice
Nol necessary IO normalize
Temper at I75 to 260 “C (315 to 500 “Fj. Approximate hardness as it corresponds to tempering temperature. 6-t to 58 HRC
Recommended l l
Annealing.
Heat to X-IS to 870 “C t IS55 IO 1600 “F). Use lower limit for small sections and upper limit for large sections. Holding time varies from approximately I h for light sections and small furnace charges. tcr approsimateI> 4 h for heavy sections and large charges. For pack annealing. hold for I h per inch of cross section. Avoid surface carhurization. uhich drastically impairs metal flow when hohhinp. Cool at a maximum rate of
l l l l l l
Processing
Rough machine Stress relieve toptional. Finish machine Carrhurize Harden Quench Temper Final grind and polish
hetueen
Sequence
and after final hohhingj
case
584 / Heat Treaters
Guide
P5: Jominy Hardenability. Source: Carpenter Technology
Carburized at 925 “C (1695 “F). Corporation
584 / Heat Treaters
Guide
P6 Chemical COmpOSitiOn. AISI: Nominal. 0.10 C. 1.50 Cr. 3.50 Ni. AISl/UNS (T51606): Composition: 0.05 to 0. IS C. 0.35 to 0.70 hln. 0.10 to O.-IO Si. 3.2 to 3.75 Ni, I.25 to I.75 Cr Similar DIN
Steels (U.S. and/or Foreign). ASThl A68 I I P-6); t&r. I 1.2330. 1.273s. 1.1715: c’Fr.1 AFNOR 2882 IO NC 12: tJap.) JIS
G-CIIOSKC3I:(U.K.)B.S.~hS9(11Sr\P20)
Characteristics.
A hobbing grade with fairI> high hnrdenabillty. Cnnnot be annealed to a hardness much lower than I83 HB. because the high nickel content strengthens the ferrite. Consequently. the mold cavity is often machined rather than hobbed. Has high core strength. and small sections can be air quenched. LOU resistance to softening at elevated temperature. medium resistance to wear. and high resistance to dscarburization
Forging.
Start forging at 1065 to I l7S
Recommended
Heat Treating
Practice
“C I IS IF, per h. The maximum rate ib not critical after cooling S40 ‘C ( IWO “F,. T> pical anneakd hardness. 183 to 2 I7 HB
Stress Relieving. Optional. Heat to 6SO to 67S “C ( I200 to 12-15 “F) and hold for I h per Inch of cross section (minimum of I hi. Cool in air Hardening. Cxburire at 900 to Y2S “C I I650 to I695 “F) to desired case depth. Harden at 790 to 815 “C I 1450 to IS00 ‘F). Hold at austenitizing temperature for IS mtn once the temperature ISuniform throughout the tool. Quench mall actions in air and larger sections m oil. Approliimate quenched hardness. 60 to 62 HRC Stabilizing. Optional. For intricate shapes. stress relieve temper 31 I SO to I60 ‘:‘C 1300 to 320 “F, brietl!. Rsfriiipsrate at -100 to -195 ‘C C-150 to -320 “FI. Temper immediateI> at&r part reaches room temperature Tempering. tempered HRC
Not necessq
to normalize
l l
Annealing.
Heat to 845 to 870 “C ( I SSS to I600 “F). 11s~lo\\ er limit for small sections and upper limit for large sections. Holding time \arie< from approximateI> I h for light sections and small furnace charges. to appro\imatell 4 h for heab y sections and large i-hays. For pack annealing hold for I h per inch of cross section. Avoid surface carburization. which drastically impairs metal tlo\i u hen hobbing. Cool at B malimum rat? of8
Temper at I75 to 230 “C r31S to -115 “F). Approximate hardness as it corresponds to tempering temperature. 61 to 58
Recommended l
Normalizing.
to below
l l l l l l
Processing
Rough machine Stress relieve (optIonal. Finish machine Carburire Harden Qwnch Stabilize (optional) Temper Final grind and poliyh
Sequence
between and utier tinal hobbmg)
Tool Steels / 585
P6: End-Quench Hardenability. Hardness of P6 carburized bars containing 3.5% Ni and 1.5% Cr, along end-quench hardenability bar at various case-depth levels. Note decrease in hardness with increasing carbon content because of retained austenite. ASTM grain size: 7 to 8
P6: Isothermal Transformation Diagram. Composition of alloy: 0.10 C, 0.34 Mn. 0.20 Si, 3.51 Ni, 1.66 Cr, 0.06 MO. Austenitizing temperature was 790 “C (1455 “F). Source: Carpenter Technology Corporation
P6: Jominy Corporation
Core Hardenability.
Source: Carpenter Technology
Tool Steels / 585
P20 Chemical
Composition. AISI: Nominal. 0.35 C. I .70 Cr. 0.40 hlo. AISI/llNS (T51620): Composition. 0.28 to 0.40 C. 0 60 IO I .OOhln. 0.X.) tn 0.80 Si. I .40 lo 2.00 Cr. 0.30 to 0.55 hlo
Similar
Steels (U.S. and/or Foreign). ASThl (Ger.) DIN 1.731 I. 1.333. 1.2310: tFr.1 AFNOR AM-S90Z 7: tSusd.) SS WS.4 P2Ot: t1J.K.b B.S. 46% tllSA PYN
A68 It P-20): 333 35 CHD
Characteristics.
hledium hardenrng rude \rith high core toughness. low softening resistance at ele\ ated temperature. and high decarhuriration resistance. lkunlly purchased tn preheat treated condition u ith ;1hardness of approsimately 300 HB. Cn\it> is machined and ma) be used at this hardness. For maximum wear resistance. molds may be carhurired or mtridcd
Forging.
Start forsing at 1010 to I I20 “C I 1850 IO 2OSc) ‘F). Do not forge below 870 “C t I600 “F)
Recommended Normalizing.
Heat Treating
Practice
Normalize at YOO“C t l6ScJ ‘F,
Annealing.
Heat to 760 to 791)‘C t l-100 to I-ISS “F). Use lower limit for small sections and upper limit for large sections. Holding time varies from approGmatel> I h for light sections and small furnace charges. to approximateI!, -I h for hsnv! sections and large charses. For pack annealing. hold for I h per inch of cross section. Avoid surface carhurization, which drasticnll~ impairs metal flow when hobhinp. Cool at a maximum rate of ” “C (10 “Ft per h. The maximum rate is not critical after cooling to below ?kJ “C ( IO00 “F). Typical a~~nlrcl hardness. I49 to 3 I? HB
Stress Relieving.
Optional. Heat tn 650 to 675 “C t 1100 to 12.45“F) and hold for I h per inch of cross section (minimum of I h). Cool in air
588 / Heat Treaters
Guide
Hardening. Carburize a~870 to 900 “C ( I600 to 1650 “F) to desired case depth. Harden at 8 I5 Lo 870 “C (1500 to 1600 “F). Hold at austenitizing temperature for IS min once the temperature is uniform throughout the tool. Quench in warm. agitated oil. Nitriding is a suitable alternative for dies used in die casting
Recommended l l l l
If not carburizrd and a hardness of 37 1028 HRC is desired.
temper at 480 to 595 “C (895 to I IO5 OF). If carburized, temper at I75 Lo 230 “C (345 to 4-U “F) for an approximate hardness of 62 to 58 HRC. This
grade can be nitrided using conventional nitriding practice. The die should be quenched and tempered to approximately and then nitrided
Rough machine Stress relieve (optional) Finish machine Preheat (large or intricate11
l
Carburize Harden Quench
l
Temper
l
Final grind and polish
l
Tempering.
Processing
l
Sequence
shaped tools)
300 HB, the cavity machined.
P20: Hardness vs Austenitizing and Tempering Temperatures. P20 austenitized at 845 “C (1555 “F) and oil quenched. Asquenched hardness, 53.5 HRC. When austenitized (1650 “F) and oil quenched, the as-quenched hardness is 54.5 HRC. Source: Universal-Cyclops
Surface
t of Carburizing for P20
Hardness
atSpecimens 900 “C burizing
Temperature
on Case De
were 25-mm (1 -in.) cubes, held 2 h at temperature compound and quenched in oil
Carburizing temperature OC
OF
845 870 900 925 955 980
1555 1600 1650 1700 1750 1800
Surface hardness. HRC
65.6 64.2 62.5 59.2 58.6 58.6
in car-
Case depth In.
mm
0.014 0.017 0.016 0.020 0.022 0.028
0.356 0.432 0.406 0.508 0.559 0.711
Source: Teledyne VASCO
P20: Tempering Characteristics (Carburized). Surface hardness of P20 after heating at 900 “C (1650 “F) and 845 “C (1555 “F) for 2 h in carburizing compound, oil quenching, and tempering
P20: End-Quench Hardenability. P20 tool steel after quenching and tempering at indicated temperatures for 2 h. Steel austenitized at 855 “C (1570 “F). Source: Teledyne VASCO
Tool Steels / 587
P20: Isothermal Transformation Diagram. P20 containing 0.30 C, 0.75 Mn, 0.50 Si, 0.80 Cr, and 0.25 MO and austenitized at 845 “C (1555 “F). Source: Crucible Steel
Tool Steels / 587
P21 Chemical Composition.
AM: Nominal. 0.20 C. 4.00 Ni. I.20 Al. AISI/UNS (T51621): Composition: 0.18 to 0.22 C. 0.20 to O.-IO Mn. 0.20 to 0.40 Si, 3.90 to 1.25 Ni, 0.50 Cr max. 0. IS to 0.25 blo, I .OS to I.25 Al
Similar Steels (U.S. and/or Foreign).
ASTM
~68 I(P-2 I )
Characteristics.
An age-hardening tool steel. When heat treating. a high-temperature tempering treamlent is used to lower hardness and enable the cavity to be machined. Final hardening occurs dunng aging. This grade can be nitrided. but should not be carburized. Is deep hardening. with medium softening resistance at elevated temperatures. and high decarburization resistance
Forging. Start forging at 109s to I IS0 “C (2005 to 2 100 “F). Do not forge below 955 “C ( I750 “F)
Stress RelieVing. Optional. Heat to 650 to 675 “C (I 200 to 1245 “F) and hold for I h per inch of cross section (minimum of I h). Cool in air Hardening.
Solution treat by heating slowly to 705 to 730 “C (I 300 to I350 “F) and holding for 60 mm for small sections to 180 min for large sections. Do not preheat. Cool in air or quench in oil to accelerate cooling. Approximate hardness range, 2-l to 28 HRC. After machining, age harden at 5 IO to 550 “C (950 to 1070 “F). holding at temperature for 20 h for small sections and up to 23 h for large secttons. Approximate aged hardness. 40 to 30 HRC. This grade cannot be carburized. but may be nitrided by holding in a gas nitriding furnace containing ammonia for 20 to 24 h at 510 to 525 “C (950 to 975 “F). Case depth will be approximately 0. I52 to 0.203 mm (0.006 to 0.008 in.) with a hardness of 91 HR I5N
Recommended
Recommended
Heat Treating
Practice
Heat to 900 “C ( 1650 ‘F). rZfter uniform through heating, holding time varies from approximately IS min for small sections to about I h for large sections. Work is cooled from temperature in still air
Annealing.
Do not anneal
Sequence
l l
4ge
l l
Normalizing.
Processing
Normalize (if not purchased ready for solution treating) Solution treat Quench Rough machine Stress relieve (optional. below aging temperature such as 400 to 425 “C or 750 to 800 OF)) Finish machine
l
l l
588 / Heat Treaters
Guide
P21: Microstructures. (a) 4% nital, 500x. Annealed by slow cooling from hot working. Principally pearlite (dark) and ferrite (white). Some austenite is probably present. (b) 4% nital, 500x. Solution treated by holding 1 h at 900 “C (1650 “F), water quenching, reheating to 730 “C (1350 “F), holding 1 h, water quenching. Structure: martensite. (c) 44, nital. 500x. Solution treated as in (b), then aged by holding 20 h at 510 ‘C (950 “F). Precipitate at grain boundaries and within grains has not been identified
Hot Work Tool Steels (H Series) Introduction The hot worh tool steels are divided into three major groups: chromium. tungsten. and molybdenum. The distinction is intended to indicate the principl alloying addition. although all steels contain chromium in amounts varying from 2 to I?r. All are used extensively for hot work applications. Because these steels are either partially or completely air hardening. normalizing is not recommended. Recommended annealing temperatures. cooling practice. and expectsd hardnsss \ alues are given m the sections that follow. Heating for annealing should be SIOH and uniform to prevent cracking especially when annealing hardened tools. Heat losses from the furnace usually determine the rate of cooling: large furnace loads itill cool at a slower rate than light loads. The H steels are extremely susceptible to both carhurizinp and decarhurizing and must be carefully protected against both. Use packing. controlled atmosphere. or a vacuum. Stress relieving tools of hot work steel can be beneticial if done after rough machining hut before fmal machining. Heat tools to 650 to 730 ‘;C ( I200 to I350 “F). This treamtent minimizes distortion during hardening. particularly for dies or tools ha\ ing major changes in configuration or deep cavities. Closer dimensional control may be obtamed by hardening and tempering after rough machining and prior to final machming. Ho\\ever. final hardness obtained hy this method should be w tthin machinable range. With few exceptions. preheating is recommended prior to austenhizing hot work steels. Rapid heating from the preheating temperatures to the austenitiztng temperature IS preferred for types H I9 through H43. IVith the exception of steels HI0 through HI-L time at the austenitizing temperature should only be sufftcient to heat the work completely through. Prolonged soaking is not
recommended. Tools or dies made of hot work steel must he protected against carburization and decarhurizntion u hen being heated for austenitizing. An endothemtic atmosphere produced by a gas generator is probably the most N idely used medium. The de\\ point is normally held from 3 to 8 “C (5.5 to IS “F) in r/w ~rrn~rcc. depending on the carbon content of the steel and the operating temperature. A dew point of 3 to 4 “C (5 to 7 “F) is ideal for types HI I and HI3 when austenitized at 1010 “C (1850 “F). hloltsn salt baths are also u idely used. In small shops where the use of a protective atmosphere is not feasible because of equipment costs, the work is packed in spent pitch coke hefore heating it for austenitizing as a common practice. from high to extremely high in hardenability. Hot uork steels rangs hlost itill achieve full hardness by cooling in still air. However. even with the steels having the highest hardenahility. sections of die blocks may he so large that insufficient hardening results. In such instances. an air blast or an oil quench (IIPIY~ a uater quench) is required to achieve full hardness. Some of the H steels. especially: the tungsten and molybdenum types. will scale considerably during cooling to room temperature in air. An interrupted quench reduces this scaling by eliminating the long period ofcontact u ith air at elevatsd temperature. hut it also increases distortion. Hot Hark tool steels should be tempered immediately after quenching, although sensitivity to cracking at this stage varies considerably. Multiple tempering serves to transform retained austenite and to minimize cracking due to h,ardening stresses. The H steels containmg 0.35% or less carbon are occasionally carhunzed to achieve a very high surface hardness (HRC 60 to 62). For some applications. the steels are nitrided after hardening and lsmpennp.
HlO Chemical COIIIpOSitiOn. AISI: Nommal. 0.40 C. 2.50 hln. 3.25 Cr. (T20810): Composition: 0.3S to O.-IS C. 0.25 to 0.70 0.40 V. AISI/UNS hln. 0.80 to 1.20 Si. 0.30 Ni max. 3.00 to 3.75 Cr. 2.00 to 3.00 hlo. 0.5 to 0.75 v
Similar
Steels (U.S. and/or
Foreign).
.L\STMA681 (H-IO): FED
QQ-T-570tH-lO):(Ger.) DIN 1.2365. 1.2367;tFr.) AFNOR .L\3S-5903431 FZ 38 CDV 5: (Jap.) JIS G-l-IO-l SKD 7: (,lJ.K.) B.S. -1659 BHIO
Characteristics. Louest in alloy content of the hot \vork steels. but offers deep-hardening properties at relati\sly low cost. Has high toughness and can be watercooled in sen Ice. Can he carbunzcd or nitrided to Increase surface hardness uith some loss in resistance to heat checking. Has very IOU distortion in heat treating. high resistance to softening at elevated temperature and medium wear resistance. Has medium to high machinahility and medium resistance to decarburization Forging.
Heat slow Iy. Preheat at 705 to 815 “C ( I300 to IS00 “F). start forging at 1065 to I I SO “C ( I950 to 2 100 OF). Do not forge after tcmperature of forging stock drops helow 900 “C t 1650 “FL Cool do\~ I)
Recommended Normalizing.
Heat Treating
Practice
Do not normalize
Annealing. Surface protectton agamst decarbunzation by use of pack. controlled atmosphere. or vacuum is required. Heat to 845 to 900 “C ( 1555 to I650 “F). Use lo\\eer limit for small sections and upper limit for large sections. Heat slowly and uniformly. especially for hardened tools. Holding time varies from about I h for light sections and small furnace charges to about -I h for hea\ y sections and large charges. For pack annealing. hold I h per inch of cross section. Cool slowly in furnace to S-IO “C (1000 “F) at a rate not to exceed 30 “C (55 “F) per h. after which a faster cooling rate will not affect final hardness. Typical annealed hardness. I93 to 229 HB StreSS RekWing. Optional. Heat to 650 to 675 ‘C (I 200 to 1245 “F) and hold for I h per inch of cross section (minimum of I h). Cool in air
Hardening. Surface protection against decarburization or carhurization is required by utilizing molten salt bath, pack. controlled atmosphere. or vacuum. For preheating. die blocks or other tools for open furnace treat-
590 / Heat Treaters
Guide
ment should be placed in a furnace at a temperature that does not exceed 260 “C (500 “F). Work packed in containers may be safely placed in a furnace at 370 to 540 “C (700 to 1000 OF). Once the workpieces (or container) have attained temperature. heat slowly to 8 IS “C ( IS00 “F). at a rate not to exceed I IO “C (200 “F) per h. Hold for I h per inch of thickness (or per inch of container thickness if packed). If double preheat facilities are available, such as salt baths. thermal shock can be reduced by preheating at 540 to 650 “C (1000 to 1200 “F) and then preheating at 845 to 870 “C (1555to 16OO”F).Austenitizeat IOIOto lO40”C(l850to 1905”F)for I5 to 40 min. Use shorter time for small sections and longer time for large sections. Quench in air. If air blast cooled, air should be dry and blasted uniformly on the surface to be hardened. To minimize scale. tools can be flash quenched in oil to cool the surface to below scaling temperature [approximately 540 “C (1000 OF)], then cooled in air, but this increases distortion. The safer procedure is to quench from the austenitizing temperature into a salt bath held at 595 to 650 “C (I IO5 to I200 “F), and hold in the quench until the workpiece reaches the temperature of the bath. Then withdraw the workpiece and allow it to cool in air. Quench hardness. 52 to
59 HRC Stabilizing.
Optional. For intricate shapes. stress relieve temper at 1%) to 160 “C (300 to 320 “F) briefly. Refrigerate at -100 to -19.5 “C (-150 to -320 “F). Temper immediately after part reaches room temperature
Tempering.
Temper immediately after tool reaches about 50 “C ( I20 “F) at 540 to 650 “C (1000 to I200 “FL Forced-convection air tempering furnaces heat tools at a moderately safe rate. Salt baths are acceptable for small parts but may cause large or intricate shaped dies to crack due to thermal shock. Temper for I h per inch of thickness, cool to room temperature, and retemper using the same time at temperature. The second temper is essential and a third temper is beneticial. Approximate tempered hardness. 56 to 39 HRC
Recommended l l l l l l l l l
Processing
Sequence
Rough machine Stress relieve (optional) Finish machine Preheat Austenitize Quench Stabilize (optional) Temper Final grind to size
HlO: Isothermal Transformation Diagram. HlO tool steel: 0.40 C, 0.55 Mn, 1 .OO Si, 3.25 Cr, 2.50 MO, 0.33 V. Austenitized at 1035 “C (1895 “F). Source: Crucible Steel
Tool Steels / 591
HlO: Hardness vs Tempering Temperature. HlO, air cooled from 1040 “C (1905 “F) and 1010 “C (1850 “F). Double tempered. Source: Universal-Cyclops
Tool Steels / 591
Hll Chemical Composition. AM: Nominal. 0.35 C, I._50 Mn. 5.00 Cr. 0.10 V. AM/UN!5 (T20811): Composition: 0.33 to O.-t3 C. 0.20 to 0.50 Mn. 0.80 to 1.20 Si. 0.30 Ni mas. -I.75 to 5.50 Cr. I. IO to 1.60 MO. 0.30 to 0.60 v Similar
Steels (U.S. and/or
6188: ASTM A68 I (H-I I ); (HI I). J-t67 (HI I ): (Ger.) A35-590 3131 FZ 38 CDV C&t404 SKD 6; (U.K.) B.S.
Characteristics.
Foreign). AM 6337. 648s. 6487. FED QQ-T-570 t H- I I); SAE 5437 (,H I I ). J-I38 DlN I .23-t3. 1.7783, 1.7784: (Fr.) AFNOR 5: (I1al.j 1JNI X 35 CrMo OS KU: c,Jap.) JIS BHI I
A popular and relatively economical grade of hot work steel suitable for many applications. Is deep hardening, has excellent resistance to heat checking, and can be water cooled in servtce. Can be carburized or nitrided \rith some loss in resistance to heat checking. Has high resistance to softening at elevated temperature. Hardness does not vary up to 595 “C (I IO5 “F). and tools can withstand Norking temperature up to 595 “C (I IO5 “F). Does not exhibit notable secondary hardening effect during tempering because of low carbon content, Hardness begins to drop off rapidly when tempering nbo\e 565 ‘C r 1050 “F). Has high toughness. very IOU distortion in heat treating. and medium wear resis-
lance. Has medium-to-high burirntion
machinability
and medium resistance to decar-
Forging.
Heat slou ly. Preheat at 705 IO 8 I5 “C ( I300 to I SO0 “F), start forging at IO65 to I I SO “C ( 1950 to 2 100 “F). Do not forge after temperature of forging stock drops belo\v 900 “C (I650 “F). Cool slowly
Recommended Normalizing.
Heat Treating
Practice
Do not normalize
Annealing. Surface protection against decarburization by use of pack. controlled atmosphere, or vacuum is required. Heat to 845 to 900 “C (I555 to 1650 “FL Use lower limit for small sections and upper limit for large secttons. Heat SIOU ly and uniformly. especially for hardened tools. Holding time varies from about I h for light sections and small furnace charges to about 1 h for heavy sections and large charges, For pack annealing, hold I h per inch of cross section. Cool slowly in furnace to 540 “C (1000 “F) at a rate not to exceed 30 “C (55 “F) per h. after which a faster cooling rate will not affect final hardness. Typical annealed hardness. 192 to 235 HB Stress RdieVing. Optional. Heat to 650 to 675 “C t 1200 to I245 “F) and hold for I h per inch of cross section (minimum of I h). Cool in air
592 / Heat Treaters Guide Hardening. Surface protection against decarburization or carburization is required by utilizing salt. pack. controlled atmosphere. or wcuum. For prehsatinp. die blocks or other tools for open furnace treatment should be placed in a furnace at ;1 tempernture that does not exceed I60 “C I SO0 “F). Work packed in contrliners may be safely placed in B timncc at 370 to S-10 “C (700 to 1000 “FL Once the uorkpieces lor container) have attained temoerature. heat slow Iv to 8 IS “C t IS00 “FL ;It ;I rate not to excsed I 10 “C i200 “F) per h. Hoid for I h per inch of thickness (or per inch of container thickness if packed). If double preheat fxilitirs me a\ailahle. such ;is salt baths. thermal shock can be reduced b) preheating at S-10 to 650 “C i 1000 to I200 “FI and then prehsnting ilt 8-!S to X70 “C ( 15% IO 160O”jF). .L\ustenitize at 9% to 1025 “C t l82.i to 1875 “‘F) for IS to-IO mm. Use shorter time for small sections and longer time for large sections. Quench in air. If air blast cooled. air should be dry and Hasted uniformI) on the surface to be hardsnsd. To minimize scale. tools citn he flash quenched in oil to cool the surface to belo\% scaling temperature [approximatelq S-IO “C t 1000 ‘F)]. then cooled in air. but this incrcnses distortion. The safer procedure is to quench from the wstenitizing temperature into a Salk bath held at 5% to 650 “C ( I IO5 to IZOO “F). nnd hold in the quench until the \\orkpiece reaches the tempernture of the bath. Then withdraw the norkpiece and allow it to cool in air. Quench hxdness. 53 to SS HRC
Tempering.
Temper immediateI> atier tool reaches about 50 “C t 110°F) IO 1300 “F). Forced-convection ;iw tempering furnaces heat tools ;11 il moderateI> safe rate. Salt baths are acceptable for small parts but mn> C;IUX huge or intricate shaped dies IO crack due to themlal shock. Temper for I h per inch of thickness. cool to room temperature. md retemper using the same time ut temperature. The second temper is essential nnd il third temoer is beneficial. Annroximate temoered hard’ ness. S-l IO 38 HRC
;11 S-IO to 650 “C (I000
I
Recommended l l l l l l l l l
Rough machine Slress relic\ e (optional Finish machine Preheat Austsnitizs Quench Stnbilize ioptionnl) Temper Finn1 grind IO sire
Processing
I
Sequence
1
Stabilizing.
Optional. For intricate shapeb. stress relie\r temper 91 IYJ to 160 “C (300 to 3X “F) brietl). Refrigerate ;It -100 IO -1% “C (-150 to -?N “FL Temper ImmediateI) after part reaches room tsmperaturs
Hll: Isothermal Transformation Diagram. Hll tool steel: 0.40 C, 1.05 Si, 5.00 Cr, 1.35 MO, 0.35 V. Austenitized at 1010 “C (1850 “F). Source: Crucible Steel
Tool Steels / 593
Hll : Hardness vs Austenitizing 1. (d) 0, consumable-electrode
and Tempering Conditions. (a, b. c) tempered: 0,O.l vacuum melted. A air melted
h;
l ,0.5 h; 1, 1 .O h; A, 2.5 h: Cl, 10.0 h; H, 100.0
594 / Heat Treaters
Guide
Hll : Hardness vs Austenitizing
and Tempering Temperature.
Hll air cooled from 995 “C (1825 “F), 980 “C (1795 “F), 970 “C (1775 “F). Source: Universal-Cyclops
Hll : As-Quenched Hardness vs Austenitizing
Tempera-
ture.Hll toolsteel:0.38C, l.OOSi.5.25Cr, 1.35Mo,0.50V. Test specimens: 25.4 mm (1 in.) diam, 76.2 mm (3 in.) long. Cooled in air. Source: Columbia Tool Steel and Latrobe Steel
Hll: Hardness vs Austenitizing
and Tempering Temperature.
English grade of Hll tool steel. Source: British Steel
Tool Steels / 595
Hll:
Elevated-Temperature
Carpenter Technology
Tensile Strength. Source:
Corporation
596 / Heat Treaters
Guide
Hll: Microstructures. (a) 30/onital, 1000x. As received (mill annealed). Fine dispersion of small spheroidal carbide particles in a matrix of ferrite (white). Grain boundaries (black lines) revealed by the etch in several areas. (b) Picral with HCI, for 10 sec. 500x. Annealed byaustenitizing at 870 “C (1600 “F), holding for 20 h, cooling to 650 “C (1200 “F) at 8 “C (15 “F) per h, then air cooling. Spheroidal, lamellar and grarnboundary alloy carbide (pnmarily, chromium carbide) in ferrite. (c) 3% nital, 1000x. Austenitized at 1010 “C (1850 “F), cooled in still air. Mainly untempered martensite with some very small spheroidal panicles of carbide and some retained austenite (the latter two constituents are not well resolved at 1000x). (d) 3% nital, 1000x. Austenitized at 1010 “C (1850 “F), arr cooled. double tempered (2 h plus 2 h) at 565 “C (1050 “F), a common heat treatment for this steel. Hardness, 54 HRC. Very fine spheroidal particles of carbide (small black or white dots) in a matrix of tempered martensite (grayish). (e) 3% nital, 1000x. Austenitized at 1010 “C (1850 “F), air cooled, double tempered (2 h plus 2 h) at 620 “C (1150 “F). Hardness, 42 HRC. Fine spheroidal alloy carbide in a matrix of tempered martensite. Change in matrix from (d) due to higher tempering temperature. (f) 2% nital, for 90 sec. 500x. Austenitized at 1120 “C (2050 “F), oil quenched, double tempered (2 h plus 2 h) at 595 “C (1105 “F). Hardness, 46 to 48 HRC. Coarse tempered martensite with a few spheroidal particles of alloy carbide. Most carbide dissolved because of the high austenitizing temperature. (g) 3% nital. 1000x. Austenitized at 925 “C (1695 “F), air cooled, double tempered (2 h plus 2 h) at 565 “C (1050 “F). Hardness, 37 HRC. Ferrite (white), spheroidal carbide, and tempered martensite. showing underbeating. (h) Nital, 1000x. Austenitized at 1150 “C (2100 “F), air cooled, double tempered (2 h plus 2 h) at 565 “C (1050 “F). Hardness, 55 HRC. Fine spheroidal carbide In coarse tempered martensrte and retained austenite. showing overheating. (j) Austenitized 1 h at 1230 “C (2245 “F), air cooled, tempered 2 h at 565 “C (1050 “F). Very coarse tempered martensite, due to high austenitizing temperature. (ASTM grain size of prior austenite is larger than 1). Retained austenite also present
Tool Steels / 597
H12 Chemical
Composition. AISI: Nominal. 0.35 C. I .SO I\‘. S.00 Cr. (T20812): Composition: 0.30 to 0.40 C. 0.20 I.50 hlo. 0.10 V. AlSI/UNS to 0.50 hln. 0.80 to I .?O Si. 0.30 Ni max. 4.75 to 5.50 Cr. I .?S to I.75 hlo. I .OO to I .70 W. 0.50 I’ ma\ Similar Steels (U.S. and/or Foreign). ASThl A68 I I H- I?); FED QQ-T-570 (H-l?): SAE 51.37 (HI?). 5438 (HI?). 5167 (HI?): tGsr.) DIN 1.2606; (Fr.) AFNOR A3S-590 3432 Z 35 CWDV S: (Ital.) LrNl X 35 CrhloWOS KU: (Jap.) JIS G-UO-1 SKD 62: tl1.K.) B.S. 4659 BHI? Characteristics. A popular grade hn\ing \eq high toughness. H:I> e,xcellent resistance to heat checkmp and can be irater cooled tn SW ice. Cnn be c~burired or nitrided to tnc‘rease surfrlcc hardness with some loss in resistance to heat checking. A specinl die catinp Fade is nvailahls. Is suitahle for extrusion dies. die castin@ dies. mandrels. hot shexs. and hot forging dies and punches. Hx high reststunce to softstung at ele\ ared tempemture. Httrdnes\ does not \ urj up IO -125 “C (800 “FI snd tools can \\ ithbtand \+orbin& temperatures up IO S-W ‘C ( IO00 “F). Does not e\hihit notable second+ hardening etkct during tempering hecause of low carhon content. Httrdnsss begins to drop off rnpidlj when tsmperinp nhove 595 “‘C t II00 “F). Is deep hardening and has lo\\ distortion in hentinp treating. Hns medium \ieii~ resist;lnce. medium to high muchinabilit! nnd medium reststilnce to dscxburizution
preheating. die blochs or other 1001s for open furnace treatment should be placed in TVfurnace at :l temperrlture that does not exceed 260 “C (500 “F). Lf’ork packed in containers ma> be safely placed in a furnace at 370 IO S-10 “C 1700 to 1000 “‘F). Once the \rorkpteces (or container) have attained tempcrnturs. heat slow I) to 815 “C ( IS00 “F). ;Lt ;1 rate not to exceed I IO “C (200 “F) per h. Hold for I h per inch of thickness (or per inch of container thickness if packed). If douhls preheat facilities are available. such us salt bathb. thermal bhock can be reduced hq preheating at 540 to 650 “C t 1000 to I?00 “F‘, nnd then preheating at 8-15 to 870 “C (IS55 to I600 “F, Austenitizr ;I[ 99S to 1025 “C ( I825 to I875 “F) for IS to 10 min. Cke shorter time for small secttons and longer ttme for large sections. Quench in air. If air blnst cooled. nir should be dry and hlasted uniformI> on the surface to he hxdensd. To minimize scale. tools can be flash quenched in oil to cool the surface to below scaling temperature [approximntel> S-IO “C ( IOOW’F~]. hut this tncrtxses distortion. The safer procedure IS to quench from the nustenitiztng temperahtre into il salt bath held at 595 to 650 “‘C I I IO5 to I?00 “FL and hold in the quench until the workpiece renches the temperuture of the hnth. Then withdraw the uorkpiece and ttllo~ it to cool in uir. Quench hwdness. S? to 55 HRC
Stabilizing.
Optionnl.
For intricnte shapes. stress relisle temper at IS0 Rsfri_gsrate at -100 to -195 “C i-150 IO -320 ‘-FL Temper immediateI> ufter part reaches room temperature
to 160 “C (300 IO 320 “FI hrietl!.
Forging.
Heat ,lo\r I!. Preheat ilt 70.5 to 8 IS “C t I300 to I SO0 “FL w-t for_gin@ ut 1065 to I I SO “C ( I YSO to 7_IO0 “FL Do not forge after tempemture of forging stock drops belo\v YOU “C I 1650 “FI. Cool slog I!
Recommended Normalizing.
Heat Treating
Tempering.
Practice
Do not norm~~lire
Annealing. Surfrrce protrxtion ayinst decurhurization b! use of pa&. controlled atmosphere. or vacuum is required. Heat to 845 to 900 “C t I SSS to 16%) “FL Use lower limit for wtnll sections nnd upper limit for Iw~s sections. Hcnt 41~~ I> llnd uniformI>. e>psciallj for hludened tools. Holding time \xics from nhout I h for light sections and small furnace charge, to about -I h for hew> sections and ltuye charg.es. For puck annealing, hold I h per Inch of cross section. Cool ~IOU I! In tumnce to S-IO “C ( 1000 “F) ;1t 3 rate not to exceed 30 “C 155 -Ft per h. nftsr which il faster cooling mte I\ ill not affect final hardness. Typical nnneulcd hardness. 19’ to 235 HB Stress Relieving.
Optional. Hent IO 650 to 675 “C I 1200 to 124s “F) and hold for I h per mch of cross section rnunimum of I hr. Cool in air
Temper tmmediatel!~aftsr tool reaches about SO “C ( I?0 “FI ut S-IO to 6%) ‘C I 1000 to 1700 ‘.Ft. Forced-comection air tempering furnaces hsut tools ttt il moderately \afe rttte. Salt baths ttre ncceptahle for mall parts hut mu! cttuse lxgs or mtncnte shaped dies to crxk due to thermal
Recommended l l l l l l l
Hardening. is required
Surface protection n_pninst decarhuriration h> utilizing salt. puck. controlled atmosphere.
H12: Hardness vs Austenitizing temper, 2 h
or carhurizxion or wx~um. For
and Tempering Conditions.
l l
Processing
Sequence
Rough mnchine Stress relis\ 5 toptionnl) Finish machine Preheat Xustsnitize Quench Stabilize (optional) Temper Finn1 grind to size
(a) H12. oil quenched.
Single
temper,
2 h. (b) H12, air quenched.
Single
598 / Heat Treaters
Guide
H12: Isothermal Transformation Diagram. Annealed H12 tool steel: 0.32 C, 0.35 Mn. 0.95 Si, 4.86 Cr, 1.45 MO, 1.29 W. Austenitized at 1010 “C (1850 “F). Critical points: AC,, 835 “C (1535 “F)
H12: Hardness vs Austenitizing and Tempering Temperature. H12 air cooled from 995 “C (1825 “F), 980 “C (1795 “F), 970 “C (1775 “F), and tempered. sal-Cyclops
Source: Univer-
H12: Tempering Temperature vs Hardness and Dimensional Change. H12: hardness and dimensional change at 2 austenitizing temperatures
Tool Steels / 599
H12: Jominy End-Quench Hardenability. H12 tool steel: 0.35 C, 0.92 Si, 4.76 Cr, 1.49 MO, 1.42 W. Source: Teledyne VASCO
H12: Isothermal
Transformation
Saville
H12: Typical Elevated-Temperature
Tensile Strength. Source: Carpenter Technology Corporation
Diagram. Source: Jessop-
600 / Heat Treaters
Guide
H12: Isothermal Transformation Diagram. Composition: 0.32 C, 0.35 Mn, 0.95 Si, 4.86 Cr, 1.45 MO, 1.29 W. Austenitized at 1010 “C (1850 “F)
600 / Heat Treaters
Guide
Hl3 Chemical
Composition. AISI: Nominal. 0.35 C, 5.00 Cr. 1.50 MO. 0.32. to 0.45 C. 0.20 to 0% I .OO V. AISI/LJNS (T20813): Composition: Mn. 0.80 IO I.20 Si. 0.30 Ni max. 4.75 IO 5.50 Cr. I. IO IO I .7S hlo. 0.80 to I.20 V
Similar Steels (U.S. and/or Foreign). ASTM A~~I(H-13): FED QQ-T-570 (H-13): SAE J-137 (Hl3). J-138 (Hl3). 5167 (Hl3): tGer.1 DIN I.2344 rFr.i AFNOR A35590 3433 Z 4OCDV 5; (Ital.) UN1 X 35 CrLlo\ OS KU: (lap.) JIS SKD61; (S\red.)SS 3242: tL1.K.j B.S.4659 BHl3.4659 HI3 Characteristics.
A very popular and available grade. Is deep hardening and has very high toughness. Has excellent resistance to heat checking and can be water cooled in service. Is suitable for a u ide range of applications including extrusion dies. die casting dies. mandrels. hot shears. and hot forging dies and punches. Has medium wear resistance. but can be carburized or nitrided to impart higher surface hardness with some loss in resistance to heat checking. Because of IOU’ carbon content. does not exhibit notable secondary hardenmg during tempering. Hardness begins to drop off rapidly when tempering aboLe -US “C (800 “F). and tools can withstand working temperatures of S-10 ‘C ( 1000 “F). Has medium to high machinability and medium resistance to decarbunzation
Forging.
Heat slowly. Preheat at 705 to 8 IS “C t I300 to I SO0 “FL ~II forging at 1065 to I I SO “C ( 1950 to 2 IO0 “Ft. Do not forge after temperature of forging SIOC~ drops below 900 “C t I650 “FL Cool slo\r Ij
Recommended Normalizing.
Heat Treating
Do not normalize
Stress Relieving. Optional. Heat to 650 to 675 ‘C ( I200 to 1245 “F) and hold for I h per inch of cross section tnunimum of I h). Cool in au
is required
Surface protection against dscarburizntion by utilizing salt. pack. controlled atmosphere,
Stabilizing. Optional. For intricate shapes. stress relieve temper at IS0 to 160 “C (300 IO 320 “F) brietlj. Refrigerate at -100 to -195 “C (-150 to -330 “FL Temper immediateI\: after part reaches room temperature Tempering.
Practice
Annealing. Surface protection against decarburization bj use of path. controlled atmosphere. or vacuum is required. Heat to X-IS to 900 “C I IS55 to I650 ‘F). Clse lower limit for small sections and upper limit for large sections. Heat slow Iy and uniformly. especially for hardened tools. Holding time varies from about I h for light sections and small furnace charges to about 4 h for hea\> sections and large charges. For pack annealing. hold I h per inch of cross section. Cool SIOU I> in furnace to S-IO ‘C ( 1000 “F) at a rate not to exceed 30 “C t 55 “F, per h. after u hich a Paster cooling rate \vill not affect final hardness. Typical annealed hardness, 192 to 229 HB
Hardening.
preheating. die blochs or other tools for open furnace treatment should be placed in a furnace 31 a temperature that does not eweed 260 “C (SO0 “F). M’orh packed in container3 ma) be safeI> placed in a furnace at 370 to S-10 “C (700 to 1000 “Ft. Once the uorkpisces tar container) have attained temperature. heat slowly to 815 “C I IS00 “F). at a rate not IO exceed I IO “C t200 “F) per h. Hold for I h per inch of thickness (or per inch of contamer thickness if packed). If double preheat facilities are available. such as salt baths. thermal shock can be reduced by preheating at 540 to 650 ‘;‘C t IO00 to I200 ‘F, and then preheating at 8-U to 870 “C ( I SSS to 1600°F). Austcnitize at 995 to 1010°C (1835 to 1905 “F) for IS to-10 min. L!se shorter time for small sections and longer time for large sections. Quench in air. If air blast cooled. air should be dry and blasted uniformly on the surface to be hardened. To minimize scale. 1001s can be flash quenched in oil to cool the surface to beIon scaling temperature [approximately 510 “C t IO(H) “F)]. but this increases distortion. The safer procedure is to quench from the austenitizinp temperature into a salt bath held at 595 to 650 “‘C t I IOS to I200 ‘F). and hold in the quench until the workpiece reaches the temperature of the bath. Then Hithdraw the uorkpiece and allow it IO cool in air. Quench hardness. 5 I to S-1 HRC
or c.arburization or vacuum. For
Temper immediateI> after rool reaches about SO “C t I20 “FI at S-10 to 6%) ‘C I 1000 IO I200 “FL Forced-comection air tempering furnaces heat tools at a moderateI> safe rate. Salt baths are acceptable for small parts but may cause large or intricate shaped dies IO crack due to thermal shoch. Temper for I h per inch of thickness. cool to room temperature. and retemper using the wme time at temperature. The second temper is essential and a third temper is beneficial. Approximate tempered hardness. 53 to 38 HRC
Recommended . Rough machine l Stress relists (optional l Finish machine l Preheat l Xustcnitizr . Quench l Stabilize toptionul) l Temper l Final grind to size
Processing t
Sequence
Tool Steels / 601
H13: Isothermal Transformation Diagram. Diagram for H13 tool steel, containing 0.40 C, 1.05 Si, 5.00 Cr, 1.35 MO, 1 .lO V. Austenitized at 1010 “C (1850 “F). Source: Crucible Steel
H13: Hardness vs Tempering Temperature. Hardness and dimensional change for H13 steel, austenitized at 540 “C (1000 “F). Source: Jessop-Saville
H13: Size Change in Hardening. Chart shows typical length changes when H 13 is properly hardened and tempered. Alloy was austenitized at 1025 “C (1875 “F), oil quenched and tempered 1 h at indicated temperatures. Source: CarpenterTechnology Corporation
602 / Heat Treaters
Guide
H13: Hardness vs Tempering Temperature . H13, air cooled from 1010 “C (1850 “F) and 980 “C (1795 “F) and double tempered. Source: Universal-Cyclops
H13: Hardness vs Tempering Temperature. (a) H13: Austenitized at 1010 “C (1850 OF), oil quenched, Austenitized at the indicated temperatures, air quenched, and tempered for 2 h
and tempered
for 2 h. (b) Hl3:
Tool Steels / 603
H13: Isothermal Phase Diagram. Austenitizing temperature was 1010 “C (1850 “F). Source: Carpenter Technology Corporation
H13: Charpy V-Notch Technology Corporation
Impact
Strength.
Source:
Carpenter
604 / Heat Treaters
Guide
H13: Microstructures. (a) 49b nital. 500x. As received (mill annealed). Held at 830 “C (1525 “F) for 2 h, cooled to 540 “C (1000 “F) at 28 “C (50 “F) per h. then air cooled. 94 HRB. Fine spheroidal particles of carbide in matrix of ferrite. (b) Picral with HCI. for 10 sec. 500x. Annealed by austenitizing at 845 “C (1555 “F), cooling to 650 “C (1200 “F) at 8 “C (15 “F) per h. then cooling in air. 11 to 12 HRC. Fine spheroidal particles of carbide (primarily chromium carbide) in matrix of ferrite. (c) 4?b nital. 500x. Austenitized at 1010 “C (1850 “F), air cooled, triple tempered (2 h plus 2 h plus 2 h) at 540 “C (1000 “F). Hardness, 53 HRC. A few spheroidal particles of alloy carbide in a matrix of tempered martensite. (d) 29/o nital, for 90 set, 500x. Austenitized at 1010 “C (1850 “F), oil quenched. double tempered (2 h plus 2 h) at 595 “C (1105 “F). Hardness, 47 to 48 HRC. Matnx of tempered martensite with a few spheroidal particles of alloy carbide. (e) 2% nital, for 60 sec. 500x. Austenitized at 1010 “C (1850 “F), oil quenched. double tempered (2 h plus 2 h) at 565 “C (1050 “F), gas nitrided 15 h at 510 “C (950 “F). Case (beginning at top) 0.152 mm (0.006 In.) deep, contains carbide and elongated nitride (white streaks). (f) 3Y0 nital, 1000x. As cast. 57 HRC. Some carbide particles in matrix of untempered martensite (dark areas) and retained austenite (light areas). White spots grain boundary carbide. Black spots nonmetallic inclusions. (g) 2% nital, 500x. Cast H13, double tempered (2 h plus 2 h) at 565 “C (1050 “F). 53 HRC. Very fine alloy carbide particles in matrix of tempered martensite (coarse, needlelike constituent). Large light gray areas retained austenite
Tool Steels / 605
H13: Isothermal
Transformation
Diagram.
Composition:
0.40 C. 1.05 Si, 5.00 Cr. 1.35 MO, 1 .l OV. Austenitized ,at lOlO’C(185O”F)
Tool Steels / 605
H14 Chemical Composition. AISI: Nomnhl. O.Jo C. s.00 Cr. 5.00 M’. AM/UN!5 (TZOSlJI: Composition: 0.35 to 0.45 C. 0.20 to O.SO hln. 0.80 to 1.20 Si, 0.30 Ni mas. 4.75 to S.SO Cr. 4.00 to 5.25 H’
‘C r70(J to IO00 ‘F,. Once the \rorhpieces (or container) have attained temperature. heat slowI> and uniformI>; to 8 IS “C t IS00 OF). at a rale not to ewwd I IO ‘-C I 200 ‘F) per h. Hold tar I h per inch of thickness (or per mch ol‘ wntainer thickness if packed,. If double preheat facilities are a\ ailabls. such as salt baths. thermal shock can he reduced h> preheating at S-IO to 650 “C I 1000 to I200 “Fl and then preheating at 835 to 870 “C (I 555 to I600 “F). Austenitize at IO IO to I Oh5 ‘T t I MO to I950 “F) for I S to JO rmn. Lise shorter time for small sections and longer time for large sections. Quench in air If air blast cooled. air should he dry and blasted uniformI> on the surface to he hardened. To minimize scale. tools can be Flash quenched in oil to cool the surface to hslow scaling temperature [approximateI) S-IO jC ( 1000 ‘F)]. hut this increases diclortion. The safer procedure is to quench from rhs nustenitirinp Iemperature into a salt hath held at 59s to 650 ‘C ( 1105 to I200 “FL and hold in the quench until the workpiece reaches the temperature of the bath. Then withdraw the uorkpiece and allow it to cool in air Quench hardness. 53 to 57 HRC
Similar Steels (U.S. and/or Foreign). .ASTI\I Ah81 IH-14): FED QQ-T-570 (H-l-!): (Ger.) DIN 1.2567; (Fr.) AFNOR 3541 Z-NJ \VC\’ S; (Jap.) JIS G-U04 SKD 4: i1l.K.) B.S. BH I I Characteristics. Contains 55 chromium and 55, tungsten. Is also available uith small additions of Lanudium (O.~Y%J, molj hdenum (0.25%). and cobalt (O.SOLY~).Has greater hot hardness and we‘ar resistance than HI I. 12. or 13. but is not as shock resistant. Can be hardened from a relatively low temperature. The isothermal transformation diagram shows the high hardenahility of this grade. Does not rxhihit notable secondark hardening during tempering. and hardness be_gms to drop off rapidI> M hen tempering ahove S-IO “C (IO00 ‘FI. Has medium machinability and restslance to decarhurization Forging. Heat sloulj. Preheat at 705 to 8 IS “C t 1300 to IS00 “F). start forging at 1065 to I I7S “C t I950 to 2 I SO “F). Do not forge after tsmperature of forging stock drops helow 925 ‘C ( I69S “F). Cool slo\~ I>
Recommended Normalizing.
Heat Treating
Stabilizing.
Optional. For intricate shapes. stress relieve temper at IS0 to I60 “C (300 to 320 OF) briefly. Refrigerate at -100 to -195 “C (-IS0 to -320 “F). Temper immediately after part reaches room temperature
Practice
Tempering. Temper immediatelv after tool reaches about SO “C ( I20 “F) at 595 to 650 “C ( I IO5 to IXO~“F). Forced-convection air tempering furnaces heat tools at a moderately safe rate. Salt baths are acceptable for small parts hut may cause large or intricate shaped dies to crack due to thermal shock. Temper for I h per inch of thickness, cool to room temperature, and retemper using the same time at temperature. The second temper is essential and a third temper is beneficial. Approximate tempered hardness. 37 to 40 HRC
Do not normalize
Annealing. Surface protection against decarhurization hj use ot’ pack. controlled atmosphere, or vacuum is required. Heat to 870 to 900 “‘C I I600 to 1650 “F). Use lower limit for small sections and upper limit for large sections. Heat slou 1~ and uniformly. especialI!, for hardened tools. Holding time varies from ahout I h for light sections and small furnace charges to ahout 4 h for hca\ y bections and large char!cs. For pack annealing. hold I h per inch of cross section. Cool slo\r I) in turnace to 59s “C ( I IO5 “F) at a we not to eweed 30 “C tSS -‘F) per h. after w hlch a faster cooling rate will not affwt final hardness. T! pical annsnled hardness. -707 to 235 HB
Recommended l
Strt?SS RelieVing. Optional. Heat IF, 650 to 675 “C I 1ZOOto 12-15 “F) and hold for I h per inch ot’sw~s section (minimum of I h). Cool in air
l l l
Hardening.
Surface protectron agiunst drcarhurization or carhuriratlon is required hj utilizing salt. pack. controlled atmosphere. or vacuum. For preheating. die blocks or other tools for open furnace treatment should he placed in a furnace at a temperature that does not esceed 260 “C t SOO“F). L’ork puched in containers ma) be ,ufel\ placed in a filmace at 370 to S-IO
H14: Hardness vs Tempering at the temperatures shown
l l l l l
Processing
Rough machine Stress relieve (optional) Finish machine Preheat Auslenilize Quench Stabilize (optional) Temper Final grind to size
Temperature.
H14 austenitized
Sequence
606 / Heat Treaters
Guide
H14: Isothermal Transformation Source: Crucible Steel
Diagram.
H14 tool steel containing:
0.40 C, 1 .15 Si, 5.25 Cr, 4.25 W. Austenitized
at 1065 “C (1950 “F).
Tool Steels / 607
H14: Isothermal
Transformation
Diagram.
Composition:
0.40 C, 1 .15 Si. 5.25 Cr, 4.25 W. Austenitized
at 1040 “C (1950 “F)
Tool Steels / 607
HI9 Chemical Composition. AISI: Nominal. 0.40 C, 4.25 Cr. 2.00 V. 4.25 W. 4.25 Co. AISI/UNS (T20819): Composition: 0.32 to 0.35 C. 0.20 to 0.50 Mn. 0.20 to 0.50 Si. 0.30 Ni max. 1.00 to A.75 Cr. 0.30 to 0.55 hlo. I .75 to 2.20 v. 3.75 to 4.50 i+
Similar Steels (U.S. and/or Foreign). ASTM A681 (H-19);FED QQ-T-570 (H-19); (Ger.) DIN 1.2678; (Jap.) JIS G4-l~ SKD 8: (U.K.) B.S. 4659 BH19 Characteristics. A chromium-tungsten grade with 28 vanadium and 3.25%, cobalt added. Requires high austenitizing temperature and short time at heat. Can be air cooled or oil quenched from hardening temperature. Exhibits greater secondary hardness than any of the H steels with identification numbers less than HI9 (HI& HI3 etc.). Hardness begins to drop off rapidly when tempering above 550 “C ( 1020 “F). Has high toughness and resistance to softening at elevated temperature. Has medium to high wear resistance. medium machinability. and resistance to decarburization Forging.
Heat slowly. Preheat at 705 to 815 “C (1300 to 1500 “F). start forging at 1040 to I 150 “C ( I905 to 2 IO0 “F). Do not forge after temperature of forging stock drops below 900 “C ( I650 “F). Cool slowly
Recommended Normalizing.
Heat Treating
Practice
“C (700 to 1000 “F). Once the workpieces (or container) have attained temperature. heat slowly to 815 “C ( 1500 “F). at a rate not to exceed I IO “C (200 “F) per h. Hold for I h per inch of thickness (or per inch of container thickness if packed). If double preheat facilities are available, such as salt baths. thermal shock can be reduced by preheating at 540 to 650 “C ( 1000 to I200 “F) and then preheating at 845 to 870 “C (1555 to 1600 “F). Heat rapidly to austenitizing temperature or 1095 to 1205 “C (2005 to 2200 “F) and hold for 2 to 5 mm. Do not over soak. When using salt baths, reduce temperature by I4 “C (25 “F). Use shorter time for smaU sections and longer time for large sections. Quench in air. If air blast cooled, air should be dry and blasted uniformly on the surface to be hardened. To minimize scale, tools can be flash quenched in oil to cool the surface to below scaling temperature [approximately 540 “C (1000 “F)], but this increases distortion. The safer procedure is to quench from the austenitizing temperature into a salt bath held at 595 to 650 “C (I 105 to 1200 “F). and hold in the quench until the workpiece reaches the temperature of the bath. Then withdraw the workpiece and allow it to cool in air. Quench hardness. 38 to 57 HRC
Stabilizing. Optional. For intricate shapes. stress relieve temper at IS0 to 160 “C (300 to 320 “F) briefly. Refrigerate at -100 to -195 “C i-IS0 to -320 “F). Temper immediately after part reaches room temperature Tempering.
Do not normalize
Annealing. Surface protection against decarburization by use of pack. controlled atmosphere, or vacuum is required. Heat to 870 to 900 “C ( 1600 to I650 “F). Use lower limit for small sections and upper limit for large sections. Heat slowly and uniformly, especially for hardened tools. Holding time varies from about I h for light sections and small furnace charges to about 4 h for heavy sections and large charges. For pack annealing. hold I h per inch of cross section. Cool slowly in furnace to 595 “C (I IO5 “F) at a rate not to exceed 30 “C (55 “F) per h. after which a faster cooling rate will not affect final hardness. Typical annealed hardness, 207 to 24 I HB
Temper immediately after tool reaches about SO “C t I20 “F) at S-IO to 705 “C t 1000 to 1300 “F). Forced-convection air tempering furnaces heat tools at a moderately safe rate. Salt baths are acceptable for small parts but may cause large or intncate shaped dies to crack due to themral shock. Temper for I h per inch of thickness. cool to room temperature, and retemper using the same time at temperature. The second temper is essential and a third temper is beneticial. Approximate tempered hardness. 57 to 10 HRC
Recommended l
Stress Relieving.
Optional. Heat to 650 to 675 “C (I 200 to I245 “F) and hold for I h per inch of cross section (minimum of I h). Cool in air
l l l
Hardening.
Surface protection against decarburization or carburization is required by utilizing salt, pack. controlled atmosphere. or vacuum. For preheating, die blocks or other tools for open furnace treatment should be placed in a furnace at a temperature that does not exceed 260 “C (500 “F). Work packed in containers may be safely placed in a furnace at 370 to 540
l l l l l
Rough machine Stress relic\ e (optional Finish machine Preheat Austenitize Quench Stabilize toptional) Temper Final grind to Gze
Temperature. H19: Hardness vs Tempering at 1175 “C (2150 “F). Source: Jessop-Saville
Processing r
H19 austenitized
Sequence
606 / Heat Treaters
Guide
H19: Hardness vs Tempering Temperature. H19 oil quenched from 1190 “C (2175 “F) and double tempered. Source: Universal-Cyclops
H19: Hardness vs Tempering Temperature. at 1175 “C (2150 “F), and oil quenched
H19 austenitized
Tool Steels / 609
H19: Hardness vs Tempering Temperature. HI9 containing 0.42 C, 0.31 Mn, 0.21 Si, 4.12 Cr. 0.46 MO, 2.19 V, 4.26 W, 4.16 Co. Austenitized at 1175 “C (2150 “F), quenched in oil. Source: Teledyne VASCO
H19:
Elevated-Temperature Testing Temperature T 20 205 31s 115 S-10 650
OF 70 100 600 800 I ooo 1200
Impact Data Charpy Impact (V-Notch) J R-lb 7 II 8 16 II I2
5 8 6 12 9 9
Rockwell C Eardness 53 53 53 5‘4 53 SO
Tool Steels / 609
H21 Chemical
Composition.
AISI: Nominal. 0.35 C. 3.50 Cr. 0.50 I’. (T20821): Composition: 0.26 to 0.36 C. 0.15 to 0.10
9.00 Ii’. AISI/UNS
hln. 0.1s to 0.50 Si. 0.30 Ni max. 3.00 to 3.75 Cr. 0.30 to 0.60 V. 8.59 to I0.00 N
Similar Steels (U.S. and/or Foreign). ASThl.A68 I (H-2 I ); FED QQ-T-570 (H-3 I ); S.4E 1437 t H2 I ). 5438 t H:! I ): tGer. ) DIN I.158 I : (Fr.) AFNOR A35-S90 35-13 Z 30 WCV 9: iltnl.) LINI X 28 LV 09 KU: tJap.) JIS G-I-W+ SKD 5: ISwed.) SS 7730: t L1.K. I B.S. 4659 BH2 I A. 4659 H2 I Characteristics. Has the lo\rest tungsten content and 1s the most a~ailahls of the tungsten hot worh steels. Llsed u here resistance to softening is of greatest concern and resistance to shock is secondar). Can water cool tool in service. onl! if done with caution and if the design of die permits this degree of thermal shock. Requires hph austenitiring temperature and short heating time. Has appreciable sscondq hardness characteristics. Hardness in tempennp hegins to drop off at ahout 565 ‘C (1050 “FJ. High in toughness. medium to high in uear resistance. medium in machinahilit) and resistance to decarhurization Forging.
260 “C (500 “FI. Work packed in containers may be safely placed in a furnace at 370 to S-IO ‘C (700 to 1000 “F). Once the workpieces (or container) have attained tsmperature. heat slowly to 815 “C i 1500 “F). at a rate not to exceed I IO “‘C t 300 “F) per h. Hold for I h per inch of thickness (or per inch of container thickness if packed). If double preheat facilities are available. such as salt baths. thermal shock can he reduced by preheating at 510 to 650 “C I 1000 to 1200 “F) and then preheating at 845 to 870 ‘C ( IS55 to 1600 “FI. Heat rapid11 to austsnitizing temperature of 1095 to I205 ‘C (2005 to 2200 “F) and hold for 2 to 5 min. Do not over soak. When salt baths are used. reduce temperature bq II “C (15 “F). Llse shorter time for small sections and longer time for large sections. Quench in air. If air blast cooled. air should be dq and blasted uniformly on the surface to be hardened. To minimize scale. tools can be flash quenched in oil to cool the surface to helow scaling temperature [approximately 540 “C ( 1000 “F)). but this Increases distortion. The safer procedure is to quench from the austenitizing temperature into a salt hath held at 595 to 650 “C ( I IO5 to I200 “F), and hold in the quench until the itorkpiece reaches the temperature of the bath Then \
Heat slo\%Ij. Preheat at 790 to 845 “C t l-155 to 1555 “FJ. start forgin! at 1065 to I I75 “C ( I950 to 2 I SO “F). Do not forge after temperature of forging stock drops helo\\ 900 “C I 1650 “F). Cool slowI>
Stabilizing. Optional. For mtncate shapes. stress relieve temper at 150 to 160 “C (300 to 320 “F) hriefl). Refngerate at -100 IO -19s “C (-150 to -320 “F). Temper Immediately after part reaches room temperature
Recommended
Tempering.
Normalizing.
Heat Treating
Practice
Do not normalize
Annealing. Surface protection against decarburiration by use of pack. controlled atmosphere. or \ acuum is required. Heat to 870 to 900 “C t I600 to 1650 “F). Llse lower limit for small sections and upper limit for large sections. Heat slou I> and uniformI). especially for hardened tools. Holding time varies from ahout I h for light sections and small furnace charges to about 4 h for heavy secttons and large charges. For pack annealing. hold I h per inch ofcross section. Cool slowI) in hmace to S95 “C t I IO5 “F, at a rate not to exceed 30 “C (55 “F) per h. after which a faster cooling rate u ill not atTect final hardness. Tbp~cal annealed hardness. 207 to 235 HB Strt?SS RelieVing. OptIonal. Heat to 6SO to 675 “C t I200 to 1245 “F) and hold for I h per inch of cross section t nunimum of I h). Cool in air
Temper ImmedIateI) after tool reaches about SO “C (120 ‘n at 595 to 675 “C ( I I OS to I z-15 “F). Forced-convection air tempering furnaces heat tools at a moderateI! safe rate. Salt baths are acceptable for small parts hut ma! cause large or intricate shaped dies to crack due to thermal ihock. Temper for I h per inch of thickness. cool to room temperature. and retcmper using the same time at temperature. The second temper is essential and a third temper is beneficial. Approximate tempered hardness. 55 tn 36 HRC
Recommended l l l l l
Hardening.
Surface protection against decarburization or carburization is required h> utilizing molten salt bath, pack. controlled atmosphere. or vacuum. For preheatin!. die blocks or other tools for open furnace treatment should be placed m a furnace at a temperature that does not e\cecd
l l l l
Processing
Rough machine Stress relic\ e (optional) Finish machine Preheat Austsnitize Quench Stabilize (optional I Temper/double temper Final grind to size
Sequence
610 / Heat Treaters
Guide
H21: Isothermal Transformation
Diagram. Source: Carpenter
H21: Hardness vs Austenitizing Temperature. H21 containing 0.35 C, 3.25 Cr, 0.50 V, 9.35 W. Quenched in air. Specimen size: 25 mm (1 in.) diam by 127 mm (5 in.). Source: Bethlehem Steel, Vulcan-Kidd, Allegheny Ludlum
H21: Hardness vs Tempering Temperature. H21 oil quenched
H21: Hardness vs Tempering Temperature. (a) H21 austenitized at the temperatures shown, oil quenched, receiving single temper for2 h. (b) H21, austenitized at the temperature shown, air quenched, receiving single temper for 2 h
Technology Corporation
at 1175 “C (2150 “F) and double tempered. Source: Universal-Cyclops
Tool Steels / 611
H21: Hardness vs Tempering Temperature. H21 oil quenched
H21: Hardness vs Tempering Temperature. H21 austenitized
from the indicated temperatures.
at the temperature
Source: Teledyne VASCO
shown. Source: Jessop-Saville
H21: Elevated-Temperature
Tensile Strength
H21:Isothermal Transformation Diagram. H21. contalnlng0.28C. 3.25Cr. 0.25V. and 9.00 W. Austenltlzed at 2100 ‘F (1 150 “0. (Source: Crucible Steel)
612 / Heat Treaters
Guide
H21: Microstructures.
(a) 3% nital, 1000x. Annealed by holding at 870 “C (1600 “F) for 2 h and cooling to 540 “C (1000 “F) at 28 “C (50 “F) 98 HRB. Dispersion of very fine alloy carbide particles in matrix of ferrite. (b) Picral with HCI, for 10 set, 500x. Annealed by austenitizing at 900 “C (1650 “F), cooling to 650 “C (1200 OF) at 8 “C (15 “F) per h, then air cooling to room temperature. Fine particles of carbide (mainly tungsten and chromium carbides) in matrix of ferrite. (c) 4% nital. 500x. Austenitized at 1150 “C (2100 “F) and cooled in air. Hardness, 55 HRC. Fine spheroidal alloy carbide particles (mainly tungsten carbide and chromium carbide) in matrix of untempered martensite. (d) 496 nital, 500x. Austenitized at 1150 “C (2100 “F), air cooled, double tempered (2 h plus 2 h) at 555 “C (1030 “F). Hardness, 53 HRC. Fine dispersion of spheroidal alloy carbide particles in matrix of tempered martensite. (e) 2% nital, for 90 sec. 500x. Austenitized at 1150 “C (2100 “F), air cooled, double tempered (2 h plus 2 h) at 595 “C (1105 “F). Hardness, 50 to 51 HRC. Fine dispersion of spheroidal alloy carbide particles in matrix of tempered martensite per h, then air cooling. Hardness,
612 / Heat Treaters Guide
H22 Chemical
COI?IpOSitiOn. AM: Nominal. 0.35 C. 2.00 Cr. (J.40 I’. I I .OO W. AlSI/UNS (T20822): Composition: 0.30 to 0.40 C. 0. IS to 0.40 Mn. 0.15 to 0.40 Si. 0.30 Ni max. I.75 to 3.75 Cr. 0.3 to 0.50 \;: IO 00 to I I .7s N’
Forging.
Heat AOM 1~. Preheat at 790 to 8-15 “C ( 1155 to IS55 “FL start forgin! at IO65 to I I75 “C ( 1950 to 2 I SO “F). Do not forge after temperaturs ot forging stock drop> b&o\{ 900 “C t I650 ‘F). Cool slowI)
Recommended Similar Steels (U.S. and/or Foreign). QQ-l-S70
(H-22):
Characteristics.
V3er.b DIN 1.381:
ASTM ,468 I t H-XI; (Jap.) JIS G-MO-1 SKD S
FED
An I 1% tungsten hot \rorh steel. M’ater cooling! not advised. Requires high austenitizinp tempcmture and short rim? at heat. Hardness during tempering begins to drop off about 595 “C t I IO5 “FL Has high toughness and resistance to softening at els\ntcd temperature. Has medium to high near resistance and medium machinabilit) and resistance to decarburizatron
Normalizing.
Heat Treating
Practice
Do not normalize
Annealing. Surface protection against decarbunzation by use of pack. controllsd atmosphere. or vacuum is required. Heat to X70 to 900 “C ( I600 to 1650 “‘FI. Clsr lousr limit for small sections and upper limit for large sections. Heat SIOU I! and uniformly. especialI> for hardened tools. Holding time varies from about I h for light sections and small furnace charges to about 1 h for hea 1 sections and large charges. For pack annealing hold I h per inch of cross vxtion. Cool slw I> in fumace to S9S “C (I IO5 “F) at a
Tool Steels / 613 rate not to exceed 30 “C (55 “F) per h. after which a faster cooling rate will not affect final hardness. T> pical annealed hardness. 107 to 235 HB
and hold in the quench. Then withdraw in air. Quench hardness. -18 to 56 HRC
StreSS ~eheVing. Optional. Heat to 650 to 675 “C (1100 to I Z-!S ‘F) and hold for I h per inch of cross section (minimum of I h). Cool in air
Stabilizing. Optional. For Intricate shapes. stress relieve temper at IS0 to 160 “C (300 to 330 On briefly. Refrigerate at -100 to -195 “C (-150 to -320 ‘F). Temper immediately after part reaches room temperature
Hardening.
Surface protection against decarburization or carburization is required b> utilizing molten salt bath. pack. controlled atmosphere. or vacuum. For preheating. die blocks or other tools for open furnace treatment should be placed in a furnace at a temperature that does not exceed 760 “C (SO0 “F). Work pachsd in containers ~nay be safely placed in a furnace at 370 to S-IO “C (700 to IO00 “F). Once the uorkpieces (or container) have attained temperature. heat slowly to 8 IS ‘YY t I SO0 “F). at a rate not to exceed I IO “C (200 “F) per h. Hold for I h per inch of thickness (or per inch of container thickness if pa&cd). If double preheat facilities are available. such as salt baths. thermal shock can be reduced b> preheating at S-10 to 650 “C ( IO00 to I200 “F) and then preheating at 8-15 to X70 “C t IS55 to 1600 “FJ. Heat rapidly to nustenitiring temperature of 1095 to I ‘OS “C (2005 to 200 “F) and hold for :! to 5 min. Do not over soah. \Vhen salt baths are used. reduce temperature b, I3 “C (ZS “F). Llse shorter time for small sections and longer time for large sections. Quench in air. If air blast cooled, air should be dq and blasted unifomlly on the surface to be hardened. To minimize scale. tools can be flash quenched in oil to cool the surface to below scaling temperature [approximateI!, S-IO “C ( 1000 “FJ]. but this increases distortion. The safer procedure is to quench from the austcnitizing temperature into a salt bath held at 995 to 6S0 “C t I I OS to I ZOO “F).
the workpiece
and allow
Tempering.
it to cool
Temper immediately after tool reaches about SO “C (I 20 “F) at 595 to 675 “C (I IOS to I ?-lS*“F). Forced-convection air tempering furnaces heat tools at a moderately safe rate. Salt baths are acceptable for small parts but may cause large or intricate shaped dies to crack due to thermal shock. Temper for I h per inch of thickness. cool to room temperature. and retemper using the same time at temperature. The second temper is essential and a third temper is beneficial. Approximate tempered hardness. 52 to 39 HRC
Recommended l l l l l l l l l
Processing
Sequence
Rough machine Stress relieve (optional) Finish machine Preheat Austcnitizr Quench Stabilize (optional) Temper Final grind to size
H22: Isothermal Transformation Diagram. H22 containing 0.40 C, 2.00 Cr, 0.35 V, 11.50 W. Austenitized at 1175 “C (2150 “F)
614 / Heat Treaters Guide
H22: Hardness vs Tempering Temperature. H22 oil quenched from 1175 “C (2150 “F), and double tempered. Source: UniversalCyclops
H22: Hardness vs Tempering Temperature. H22 austenitized at 1065 “C (1950 “F) and oil quenched, austenitized at 1205 “C (2200 “F) and air quenched, and austenitized at 1205 “C (2200 “F) and oil quenched. Each received single temper for 2 h
614 / Heat Treaters Guide
H23 Chemical
~OITIpOSitiOn. AISI: Nominal. 0.30 C. 12.00 Cr. I .OO V, 12.00 W. AISI/UNS (T20823): Composition: 0.25 to 0.35 C. 0. I5 to 0.40 Mn, 0.15 to 0.60 Si. 0.30 Ni max. II.00 to 12.75 Cr. 0.75 to 1.25 V. II.00 to 12.75 W
Similar Steels (U.S. and/or Foreign). QQ-T-570
(H-23);
Characteristics.
ASTM
~68 I (H-23); FED
(Ger.) DIN 1.2625
A relatively low carbon grade containing 12% tungsten and 12% chromium. Has very high resistance to softening at elevated temperature and high resistance to hardness drop during tempering. Is deep hardening and exhibits unusually high secondary hardening during tempering. RequiEs high austenitizing temperature and short time at heat. At an austenitizing temperature of 1260 “C (2300 “FL has duplex structure of austenite and ferrite. On isothermal transformation. precipitation from the ferrite (of iron tungsten) begins within a few seconds which is not detrimental to as-quenched or final hardness. More important, the nose of the transformation curve is encountered in only 60 set at 980 “C (I795 “F). Therefore, oil quenching or a strongly agitated hot salt bath (preferably cascade type) at approximately 175 ‘C (345 “F) is used. The MS temperature is approximately -45 “C (-50 “F). As-quenched structure consists of undissolved carbide, austenite, and ferrite. (Absence of martensite explains resistance to tempering). As-quenched hardness, 34 to 40 HRC. During tempering, it will increase to the usual working hardness of 34 to 48 HRC. Hardness begins to drop off gradually at 510 to 595 “C (I000 to I I05 “F)
and very rapidly in the 650 to 705 ‘C ( I200 to I300 “F) range. Has medium toughness, medium to high wear resistance. and medium machinability and resistance to decarburization
Forging.
Heat slowly. Preheat at 790 to 845 “C (1455 to 1555 “F), start forging at IO65 to I I75 “C ( 1950 to 2 I50 “F). Do not forge after temperature of forging stock drops below 980 “C (I 795 “F). Cool slowly
Recommended Normalizing.
Heat Treating Practice
Do not normalize
Annealing. Surface protection againsl decarburization by use of pack, controlled atmosphere. or vacuum is required. Heat to 870 to 900 “C (1600 to 1650 “F). Use lower limit for small sections and upper limit for large sections. Heat slowly and uniformly, especially for hardened tools. Holding time varies from about I h for light sections and small furnace charges to about 4 h for heavy sections and large charges. For pack annealing, hold I h per inch of cross section. Cool slowly in furnace to 595 “C I I I05 “F) at a rate not to exceed 30 “C (55 “F) per h. after which a faster cooling rate will nor afffcr final hardness. qpical annealed hardness, 2 I2 to 255 HB Stt%?SS RelieVing. Optional. Heat to 650 to 675 “C (1200 to 1245 “F) and hold for I h per inch of cross section (minimum of I h). Cool in air
Hardening. is required
Surface protection against decarburization or carburization by utilizing molten salt bath, pack, controlled atmosphere, or
Tool Steels / 615 vacuum. For preheating. die blocks or other tools for open furnace treatment should he placed in a furnace at a temperature that does not exceed 360 “C (500 “F). Work packed in containers may be safely placed in a furnace at 370 to S-IO “C (700 to 1000 “F). Once the workpieces (or container) have attained temperature. heat slow 1~ to 8X “C t 155.5 “F). at a rate not to exceed I IO “C (XI0 “F) per h. Hold for I h per inch of thickness (or per inch of container thickness if packed). If double preheat facilities are available, such as salt baths. thermal shock can be reduced by preheating at S-IO to 6.50 “C ( IO00 to I NO “F) and then preheating at 815 to 870 “C ( IS55 to I600 “F). Heat rapidly to austenitizing temperature of I205 IO I260 “C (2200 to 2300 OF) and hold for 1 to 5 min. Do not over soak. When salt baths are used. reduce temperature h> II “C (25 “Ft. Use shorter time for small sections and longer time for large sections. Quench from the austenitizing temperature in warm oil or an agitated salt bath held at I65 to 190 “C (330 to 375 “F). and hold in the quench until the workpiece reaches the temperature of the bath. Then withdraM the ~orkpiece and allon it to cool in air. Quench hardness. 34 to -IO HRC
Stabilizing. Optional. For intrrcate shapes. stress relieve temper at I50 to 160 “C (300 to 320 “F) briefly. Refrigerate at -100 to -195 “C t-150 to -370 “F). Temper immediately after part reaches room temperature
Tempering.
Temper immediately after tool reaches about SO “C ( I20 “F) at 650 to 730 “C (1200 to I350 OF). Forced-convection air tempering furnaces heat tools at a moderately safe rate. Salt haths are acceptable for small parts but may cause large or intricate shaped dies to crack due to thermal shock. Temper for I h per mch of thickness. cool to room temperature. and retemper using the same time at temperature. The second temper is essential and a third temper is beneficial. Approximate tempered hardness. 48 to 3-t HRC
Recommended
Processing
Sequence
Rough machine Stress relieve (optional) . Finish machine l Preheat l r\ustenitize l Quench l Stahilize toptional) l Temper l Final gnnd to size l l
H23: Isothermal Transformation M, is below room temperature.
H23: Hardness vs Tempering Temperature. H23 oil quenched from 1260 “C (2300 “F) and triple Source: Universal-Cyclops
tempered
(2 plus 2 plus 2 h).
Diagram. Note that
Source:
Crucible
Steel
H23: Hardness vs Tempering Temperature. H23 containing 0.35 C, 0.33 Mn. 0.45 Si, 11.87 Cr. 1.08 V, 12.07 W. Austenitized at 1275 “C (2325 “F) and quenched in oil. Source: Teledyne VASCO
616 / Heat Treaters
Guide
H23: Hardness vs Tempering Temperature. H23 austenitized at temperature plus 2 h)
Indicated, oil quenched,
triple tempered
(2 plus 2
H23: Microstructures. (a) Kalling’s reagent, 500x. Annealed by austenitizing at 870 “C (1600 “F) for 2 h. cooling to 540 “C (1000 “F) at 28 “C (50 “F) per h, and air cooling. 98 HRB. Tiny spheroidal and some larger alloy carbide particles in matrix of ferrite. (b) Kalling’s reagent, 500x. Austenitized at 1270 “C (2320 “F) and quenched in molten salt at 175 “C (345 “F). Hardness, 40 HRC. Retained austenite (large light gray areas), ferrite (dark gray areas), and spheroidal particles of carbide. (c) Kalling’s reagent, 500x. Austenitized at 1270 “C (2320 “F), quenched in molten salt at 175 “C (345 “F), tempered at 555 “C (1030 “F). then at 790 “C (1455 “F). Ferrite (black), austenite transformed during tempering (mottled), and spheroidal carbide particles
616 / Heat Treaters Guide
H24 Chemical
COIIIpOSitiOn. AISI: Nominal. 0.15 C. 3.00 Cr. 0.50 V. IS.00 W. AISI/LJNS (T2082-t): Composition: 0.43 to 0.53 C. 0. IS to 0.40
hln. 0. IS to 0.30 Si. 0.30 Ni max . 2.50 to 3.50 Cr. 0.40 to 0.60 V. l-1.00 to 16.00 W
Similar Steels (U.S. and/or Foreign). QQ-T-570
Forging. Heat slowlj. Preheat at 790 to 8-U YY t l-i55 to IS55 “F). start forging at IO65 to I I75 ‘C ( I950 to 2 I SO “FL Do not forge after temperature of forging stock drops below 955 “C ( I750 “Fi. Cool slowI> Recommended
r\SThl
A681 (H-2-l):
Heat Treating
Practice
FED
(H-24)
Characteristics. A tungsten hot Hark grade containing I SG tuyten. 0.155, carbon. plus chromium and vanadium. Requires high austenmzing temperatrwe and short time at heat. Oil quenching is recommended rather than air. Tools should not be water cooled during hot work service. Tun_rsten steels are sensitive to rapid heatmg and cooling qcles. For this reason. they are usually finish ground with free cutting coarse grain u heels. u hich tend to reduce localized heating durmg grinding. Has mild secondan hardening characteristics, and hardness will peak out at approximately S-10 “C t 1000 “F) when austenitized at 120s “C (X00 “F). Is deep hardening has very high resistance to softening at elevated temperature. and has medium toughness. Wear resistance is high. Has medium machinability and resistance to decarburization
Normalizing.
Do not normalize
Annealing. Surface protection against decarburization by use of pack. controlled atmosphere. or vacuum is required. Heat to 870 to 900 “C ( 1600 to 1650 “FI llse loner limit for small sections and upper limit for large sections. Heat slog I> and uniformI>. especially for hardened tools. Holding time wms from about I h for light sectIons and small furnace charges to about 4 h for hew> sections nnd large charges. For path annealing. hold I h per inch of cross section. Cool slowly In furnace to 595 “C (I IO5 “F) at a rate not to exceed 30 “C 155 “F) per h. after I{ hich a faster cooling rate will not affect final hardness. T> pical annealed hardness. 2 I7 to 24 I HB Stress Relieving. OptIonal. Heat to 6%) to 67s “C ( I200 to I245 “F) and hold for I h per inch of cross section (minimum of I h). Cool in air
Tool Steels / 617 Hardening.
Surface protection npalnst dccarburizatmn or carburization is required by utilizing molten salt bath. pack. controlled atmosphere, or vacuum. For preheatlng. die blocks or other tools for open furnace treatment should be placed in a furnace at a temperature that does not exceed 260 “C (500 “F). Work packed in containers ma! be safely placed in a furnace at 370 to 510 “C (700 to IO00 “F). Once the uorkpiecss (or container) have attained temperature. heat SIOH I> to 8 IS “C I IS00 “F). at a rate not to exceed I IO ‘C (100 “F) per h. Hold for I h per inch of thickness (or per inch of container thickness if pucked’t. If double preheat facilities are available. such as salt baths. thermal shock can be reduced by prshsutin_r at 5-W to 650 ‘C ( 1000 to I200 jF) and then preheating at 845 to 870 ‘C (ISSS to 1600 “F). Heat rapidI> to nustemtizing temperature of 1095 to I230 “C (2005 to E-IS “FJ and hold for ? to 5 mtn. Do not o\er soak N’hsn salt baths are used. reduce temperature b> I-l “C (25 “F). Use shorter time for small sections and longer time for large sections. Quench in warm nil or agitated salt bath held at approximately I7S “C (335 “FL and hold in the quench until the workpiece reaches the lempernture of the bath. Then withdraw the worhpiece and nllo~ it to cool in air. Quench hardness. 52 to 56 HRC
Tempering.
Temper immediately
after tool reaches about SO “C (I 20 “F)
at 565 to 650 “C ( 1050 to IX0 “F). Forced-convection air tempering furnaces heat tools ;It ;1moderately safe rate. Salt baths are acceptable for small parts but ma! cause large or intricate shaped dies to crack due to thermal shock. Temper for I h per inch of thickness. cool to room temperature. and retcmper using the same time at temperature. The second temper is essential and a third temper is beneficial. Approximate tempered hard-
nsss. SS to -tS HRC
Recommended l l l l l l l l l
Processing
Sequence
Rough machine Stress relie\r (optional) Finish machine Preheat r\ustenitizs Quench Stabilize (optional) Temper Final grind to size
Stabilizing. Optional. For intricate shapes. stress relieve temper at I SO to 160 “C (300 to 320 “F) briefly. Refrigerate at -100 to -195 jC (-ISO to -320 “FJ. Temper immediatslv after p
Temperature. (a) H24 containing 0.42 C. 3.50 Cr, 0.30 V, 14.00 W, quenched in air. Specimen 25 mm (1 in.) diam by 127 mm (5 in.). (b) H24 containing 0.47 C, 3.50 Cr. 0.70 V, 14.00 W, quenched in air. Specimen 25 mm (1 in.) diam by 127 mm (5 in.). Source: Bethlehem Steel and Allegheny Ludlum
H24: Hardness vs Tempering Temperature. H24 austenitized at the temperatures temper for 2 h
shown, oil quenched,
and receiving
single
Tool Steels / 617
H25 Chemical
Composition. AISI: Nominal. 0.25 C. 4.00 Cr. 0.50 \‘. IS.00 H’. AlSl/UNS (T20825): Composltion: 0.22 to 0.32 C. 0. IS to 0.40 hln. 0. IS to 0.40 Si. 0.30 Ni max. 3.7S to -l.S(J Cr. 0.10 to 0.60 V. l-1.00 to Ih.00 L\
Forging. Heat slog Iy. Preheat a~ 790 to 815 “C ( I-ES to 1555 “FL start forging at I 06s to I I7S “C ( I950 to 2 I SO “F). Do not forge after temperature of forging stock drops below 925 “C ( 1695 “F). Cool slowI>
Recommended Similar QQ-T-570
Steels (U.S. and/or Foreign).
ASTM
~68 I I H-25): FED
(H-25)
Characteristics. Vq similar to H24, except has louer carbon content and I pi more chromium. A I Sri tun_esten hot \t ork grade. Its relatib el! lo\\ level of carbon gives it a toughness rating equal to the popular W tungwn grades \vhich hate higher levels of carbon. The high tungsten imparts ver) high resistance to softemng at elevated temperature. Requlrrs high austenitiring temperature and short time at heat. Cannot be eater cooled in sen ice and should be ground ~biirh coarse open I\ heel. Hardness in tempering hegins to drop after S-IO “C ( IO00 “F) u hen the high end of the austenitizing range is used. Has high toughnesb. and medium \iear resistance. machinubilit). and resistance to decarburization
Normalizing.
Heat Treating
Practice
Do not normalize
Annealing. Surface protection against decarhurization by use of pack. controlled atmosphere. or vacuum is required. Heat to 870 to 900 “C (1600 to 1650 -FL Use Io\ and uniformly. especialI> for hardened 1001s. Holding time varies from ahout I h for light sections and small furnace charges to about 4 h for hew! sections and large chnrges. For pack annealing. hold I h per inch of cross section. Cool slo\rlj in furnace to 595 “C ( I I05 OF) at a rate not to evxsd 30 “C (55 “F) per h. after u hich a faster cooling rate will not affect final h.ardnrss. Typical annealed hardness. 207 to 235 HB Stress RelieVing. Optional. Heat to 650 to 675 “C I I100 IO I US’F) and hold for I h per inch of cross action (minimum of I h). Cool in air
618 / Heat Treaters
Guide
Hardening. Surface protection against decarburization or carburization is required by utilizing molten salt bath. pack. controlled atmosphere. or vacuum. For preheating. die blocks or other tools for open furnace treatment should be placed in a furnace at a temperature that does not exceed 160 “C (500 “F). Work packed in containers may be safeI> placed in a furnace at 370 to 540 “C (700 to 1000 “F). Once the workpieces (or container) have attained temperature. heat slowly to 8 IS “C ( IS00 “FL at a rate not to exceed I IO “C (300 “F) per h. Hold for I h per inch of thickness (or per inch of container thickness if packed). If double preheat facilities are available. such as salt baths. thermal shock can be reduced b) prehsating a1540 to 650 “C (1000 to 1200 “F) and then preheating at 8-U to 870 “C ( I555 to 1600 “F). Heat rapidly to austenitizing temperature of I I SO to I?60 “C (2 100 to 1300 “F) and hold for 2 to 5 min. Do not over soak. N’hen salt baths are used. reduce temperature bq II “C (35 “F). USC shorter time for small sections and longer time for large sections. Quench in air. If air blast cooled. air should be dry and blasted uniformly on the surface to be hardened. To minimize scale. tools can he flash quenched in oil to cool the surface to below scaling temperature [approximateI) S-IO “C t lOOO”F)], but this increases distortion. The safer procedure is to quench from the austenitizing temperature into a salt bath held at 595 to 650 “C ( I I OS to I200 “FL and hold in the quench until the ~orkpiece reaches the temperature of the bath. Then withdraw the workpiece and allow it to cool in air. Quench hardness, 33 to -I6 HRC
Stabilizing. Optional. For intncate shapes. stress relieve temper at I SO to 160 “C t300 IO 3’0 “F) briefI>. Refriperate a~ -100 to -195 “C (-150 to -330 “FL Temper Immediately after part reaches room temperature Tempering.
Temper immediately after tool reaches ahout SO “C ( I20 “F) at 565 to 675 “C ( 1050 to I X5 “F). Forced-convection air tempering furnaces heat tools at a moderately safe rate. Salt baths are acceptable for small parts hut ma! cause large or intricate shaped dies to crack due to thermal shock. Tempsr for I h per inch of thickness. cool to room temperature. and retemper using the same time at temperature. The second temper is essential and a third temper is hencficial. Approximate tempered hardness. -l-l to 35 HRC
Recommended l l l l l l l l l
Processing
Sequence
Rough machine Stress relieve coptional) Finish machine Preheat Austsnitize Quench Stabilize (optional, Temper Final grind to size
H25: Isothermal Transformation
Diagram. H25 con-
taining 0.25 C. 4.00 Cr. 0.50 V, 15.00 W. Austenitized 1175 “C (2150 “F). Source: Crucible Steel
H25: Hardness vs Tempering Temperature. H25 containing 0.26C, 3.6OCr, 0.4OV, 14.30 W.Austenitizedat 1175”C(215O”F) and quenched in oil. Specimen: 13 mm (0.50 in.) diam by 15.8 mm (0.625 in.)
45
E
40
30 as quencned
at
200
400
600
800
Tempermng temperature.
IO00 -F
I200
I400
Tool Steels / 619
H26 Chemical
COtIIpOSitiOn. AISI: Nominal. 0.50 C, 4.00 Cr. I .OO V. 18.00 W. AISI/UNS (T20826): Composition: 0.15 to O.SS C. 0. IS to 0.10 hln.0.15 to0.40Si.0.30Nimax.3.75 to-t.SOCr.O.75 to I.25 V. 17.25 to 19.00 W
Similar QQ-T-570
Steels (U.S. and/or Foreign). (H-26):
(U.K.)
ASTM
A68 I (H-26):
FED
B.S. 4659 BH26
Characteristics. Hot work version of 18-4-l or TI high speed steel except with lower carbon to increase toughness IO a medium rating. The most erosion resistant and lowest shock resistant of the tungsten hot work steels. Heated in a similar manner to high speed steel. with a high austenitiring temperature and a short time at heat. Will not withstand water cooling in service. Can be quenched in salt. oil. or air. Hardness begins to drop off rapidly during tempering above approximately 525 “C (975 “F). Has medium machinability and resistance to decarburization. Available in several carbon ranges Forging.
Heat slowly. Preheat at 790 to X-15 “C (l-455 to IS55 “F). start forging at 1065 to I I75 “C ( I950 to 2 I SO “Fj. Do not forge after temperature of forging smck drops below 9.5s “C (I 750 “Fj. Cool slowly
Recommended Normalizing.
Heat Treating
Practice
Do not normalize
Annealing. Surface protection against decarburization by use of pack. controlled atmosphere. or vacuum is required. Heat to 870 to 900 “C ( 1600 to 1650 “Fj. Use lower limit for small sections and upper limit for large sections. Heat slowly and unifomrly. especially for hardened tools. Holding time varies from about I h for light sections and small furnace charges to about 4 h for heavy sections and large charges. For pack annealing, hold I h per inch of cross section. Cool slowly in furnace to 540 “C t 1000 “Fj at a rate not to exceed 22 “C (10 “F) per h. after which a faster cooling rate will not affect final hardness. Typical annealed hardness, 3 I7 to 24 I HB
container) have attained temperature. heat slowly to 870 “C (I 600 “F). at a rate not to exceed I IO “C (200 “F) per h. Hold for I h per inch of thickness (or per inch of container thickness if packed). If double preheat facilities are available. such as salt baths. thermal shock can be reduced by preheating at S-IO to 650 “C ( 1000 to 1200 “Fj and then preheating at 845 to 870 “C f IS55 to 1600 “F). Heat rapidly IO austenitizing temperature of I I75 to I260 “C (2 I SO to 2300 “F) and hold for 2 IO 5 min. Do not over soak. When sah baths are used, reduce temperature by I-t “C (25 “F). Use shorter time for small sections and longer time for large sections. Quench in salt, oil, or air. If air blast cooled. air should be dry and blasted uniformly on the surface to be hardened. To minimize scale. tools can be flash quenched in oil to cool the surface to below scaling temperature [approximately 540°C (IOOO”F)], but this Increases distortion. The safer procedure is to quench from the austenitizing temperature into a salt bath held at 595 to 650 “C (I IO5 to I200 “F). and hold in the quench until the workpiece reaches the temperature of the bath. Then withdraw the uorkpiece and allow it to cool in air. Quench hardness. 5 I to 59 HRC
Stabilizing.
Optional. For intricate shapes, stress relieve temper at I50 to 160°C (300 to 320°F) briefly. Refrigerate at -100 to -195 “C (-IS0 to -320 “Fj. Temper immediately after part reaches room temperature
Tempering.
Temper immediately after tool reaches about SO “C ( I20 “Fj at 565 to 675 “C ( 1050 to IX5 “Fj. Forced-convection air tempering furnaces heat tools at a moderately safe rate. Salt baths are acceptable for small parts but may cause large or intricate shaped dies to crack due to thermal shock. Temper for I h per inch of thickness. cool to room temperature. and retemper using the same time at temperature. The second temper is essential and a third temper is beneficial. Approximate tempered hardness as it corresponds to tempering temperature is 58 to 43 HRC
Recommended l
Stress Relieving. Optional. Heal to 650 to 675 “C (I 200 to 1215 “Fj and hold for I h per inch of cross section (minimum of I h). Cool in air
l
Hardening.
l
Surface protection against decarburization or carburization is required by utilizing molten salt bath. pack. controlled atmosphere. or vacuum. For preheating. die blocks or other tools for open furnace treatment should be placed in a furnace at a temperature that does not exceed 260 “C (500 “F). Work packed in containers may be safely placed in a furnace at 370 to 540 “C (700 to 1000 “F). Once the workpieces for
l
l l l l l
Processing
Rough machine Stress relieve (optional) Finish machine Preheat Austenitize Quench Stabilize (optional) Temper Final grind to size
Sequence
620 / Heat Treaters
Guide
H26: Hardness vs Tempering Temperature. H26 oil quenched from 1205 “C (2200 “F) and double tempered. Cyclops
H26: Microstructures.
Source: Universal-
(a) Picral with HCI, for 10 set, 500x. Annealed by austenitizing at 900 “C (1650 “F), cooling to 650 “C (1200 “F) at 8 ‘C (15 “F) per h, and air cooling. Hardness, 22 to 23 HRC. Dispersion of fine particles of alloy carbide in matrix of ferrite. (b) 4% nital, 500x. Austenitized at 1260 “C (2300 “F) and oil quenched. Hardness, 58 HRC. Small spheroidal carbide particles and some larger alloy carbide [principally tungsten carbide) in matrix of untempered martensite. (c) 4% nital, 500x. Austenitized at 1260 “C (2300 “F), oil quenched (2 h plus 2 h) at 550 “C (1020 “F). Hardness, 59 HRC. Particles of alloy carbide more clearly resolved in (b). Matrix tempered martensite
Tool Steels / 621
H42 Chemical Composition. AISI: Nominal. 0.60 C. -l.OO Cr. 5.00 MO. 1.00 L’. 6.00 M’. AlSImS (T20&I2): Composition: O.SS IO 0.70 C. 0. IS IO O.-IO Mn. 3.75 to -I.50 Cr. I.75 to 2.20 V. 5.50 to 6.75 b Similar
Steels (U.S. and/or Foreign).
QQ-T-570
(H-42);
(Fr.) AFNOR
ASTM A681 (H-X): 35-18 Z 65 WDCV 6.05
container) have attained temperature. heat slowly to 730 to 845 “C ( I350 to IS55 “F). at a rate not to exceed I IO “C (300 “F) per h. Hold for I h per rnch of thickness (or per inch of container thickness if packed). If double prehear facilities are available. such as salt baths. thermal shock can be reduced by preheating at S-IO to 650 “C ( 1000 to 1200 “F) and then preheating at 8-15 to 870 “C ( I SSS to I600 JFj. Heat rapidly to austenitizing tcmpemture of I I20 to I320 “C (7050 to 2235 ‘FJ and hold for 2 to 5 min. Do not o\er soak. H’hen salt baths are used. reduce temperature by I4 “C (25 “FJ. Use shorter time for small sections and longer time for large sections. Quench in salt. oil. or ;ilr. If air blasr cooled, air should be dry and blasted uniformly on the surface IO be hardened. To minimize scale, tools can be [lash quenched in oil to cool the surface IO below scaling temperature [approxnnately S-IO “C (1000 “F)], hut this increases distortion. The safer procedure is to quench from the austenilizing temperature into a salt bath held at 595 IO 650 “C ( I I OS to I200 “F). and hold in the quench until the workpiece reaches the temperature of the bath. Then withdraw the workpiece and allo\< it to cool in air. Quench hardness, 53 to 62 HRC
FED
Characteristics.
Hot Hark version of the popular hl:! high speed steel u ith lower carbon content to increase toughness 10 a medium rating. Has I cry hiph resistance to softening at ele\ ated temperature. Treated much like a high speed steel. requiring high austenitirinp temperature and a short time at heat. will not withstand waler cooling in service. Hardness begins IO drop off fairly rapid11 during tempering in the 5 IO IO S-IO “C (950 to 1000 “F) range. Has medium machinability and resistance to decarhurization. Available in several carbon ranges
Forging.
Heat slowI>. Preheat at 760 IO 8 IS “C ( 1300 to I SO0 “F). stan forging at lo-10 IO I I SO “C ( I905 IO 2 IO0 “F). Do not forge after temperature of forging stock drops belou 92.5 ‘YI i 1695 “F). Cool slou I)
Recommended Normalizing.
Heat Treating
Practice
Do not normalize
Annealing.
Surface protection against decarburization bl use of pack. controlled atmosphere. or vacuum is required. Heal 10 815 to 900 YY ( IS55 to 1650 “F). Use lower limit for small sections and uppsr limit for large sections. Heat slowI) and uniformI>. especially for hardened tools. Holding time vanes from about I h for light sections and small furnace charges to about -I h for heavy sections and large charges. For pack annsaling. hold I h per inch of cross section. Cool slo\r ly in furnace to 510 “C ( 1000 “F) a1 a rate not to esceed 27 “C (-IO “F) per h. after n hich a faster cooling rale will not affect final hardness. Typical annealed hardness. 207 to 2.35 HB
Stress Relieving. Oplional. Heat to 650 10 675 ‘T ( IX0 to 12.45 “F) and hold for I h per inch of cross section cminimum of I h). Cool in air
Stabilizing. Optional. For intricate shapes. stress relieve temper at IS0 to 160 “C (300 IO 320 “F) hrirfly. Refrigerate at -100 to -195 “C (-IS0 IO -320 “F). Tcmpcr immediately after part reaches room temperature Tempering.
Temper immediavlg after tool reaches about SO “C ( I20 “F) at ShS IO 650 “C II050 to I100 “F). Forced-convection air tempering tirnaces heat tools at a moderalelq safe rate. Salt baths are acceptable for small ptis hut ma) cause large or intricate shaped dies to crack due to thermal shock. Temper for I h per inch of thickness. cool to room temperature. and retemper using the same time at temperature. The second temper is essential and a third temper is beneficial. Approximate lempered hardness as it correspond> to tempering temperature is 60 to SO HRC
Recommended l l l
Hardening. Surface provcrion against dccarhurization or carbunzalion is required bq utilizinp molten salt bath. pack. controlled atmosphere. or vacuum. For preheating. die blocks or orher tools for open furnace treatment should he placed in a furnace at a temperature ihal does not exceed 260 “C (SO0 ‘F). Hbrk packed in containers ma, be safel) placed in a furnace at 370 IO S-IO “C (700 IO 1000 ‘F,. Once rhe lrorkpiscss (or
H42: Hardness vs Austenitizing Temperature. H42 containing 0.68 C. 0.30 Si, 4.25 Cr, 5.00 MO, 1.90 V, 6.40 W. Specimen oil quenched from indicated temperatures. Source: Latrobe Steel and Bethlehem Steel
l l l l l l
Rouph machine Stress relie\c (optional Finibh machine Preheat r\uslenilize Quench Stabilize ioptional) Temper Final grind 10 size
Processing
Sequence
1
H42: Hardness vs Tempering Temperature. H42 austenitized at 1205 “C (2200 “F) and 1120 “C (2050 “F) and oil quenched
l’bngsten
High-Speed
Tool Steels
(T Series) introduction Tungsten high-speed tool steels are primarily used for cutting tools such as broaches. chasers. cutters. drills. hobs. reamers. and taps. The T steels need not be normalized. but they must be fully annealed after forging or when rehardening is required. The T-series steels are always preheated prior to austenitizing to minimize the stresses that might develop because of the transformation to austenite at approximately 760 “C (I-MO “F). Double preheating is often recommended to minimize thermal shock. Only small tools and those that do not incorporate sharp notches or abrupt changes in section ma) be placed directly into the austenitizing furnace with reasonable safety. All high-speed tool steels depend on the solution of various complex alloy carbides during austenitizing to develop both their heat-resisting qualities and cutting ability. These carbides do not dissolve to any appreciable extent unless the steel is heated to temperatures approaching the melting point of the steel. Therefore. exceedingly accurate temperature control is required in austenitizing high-speed steel. A steel such as TI 5. which contains more than 3% vanadium, may be held at the austenitizing temperature about 50%, longer than those containing lesser amounts. The relatively pure vanadium carbide phase inherent in the microstructure of this steel is virtually insoluble at temperatures below the melting point and restricts grain growth, permitting longer soaking times without detriment.
However. the recommended austsmtiring temperature for this steel should not be exceeded. Single point tools intended for heavy-duty cutting can often be effectively austenitized at 8 to I7 “C ( IS to 30 “F) above the nominal austenitizing temperature to improve hot hardness and temper resistance. The higher temperature increases alloy solution. temper resistance. and hot hardness. but it also results m some sacrifice in toughness. Fine-edged tools. such as taps and chasers. ma> be hardened at temperatures I3 to 28 “C (25 to 50 “F, below the nominal austenitizing temperature to impart added toughness. Other adjustments in austenitizing temperature depend on the type of heating equipment employed. The T-series steels can be quenched in air. oil. or molten salt. The steels are normally subjected to two separate tempering treatments. Refrigeration may be used to transform retained austenite. The hardened or hardened and tempered tool is cooled to at least -85 “C t-170 “F) and tempered or retempered at normal tempering temperatures. The steels may also be nitrided. Liquid nitriding baths. capable of producing a more ductile case with a louer nitrogen content than that normally obtained in gaseous nitriding atmospheres. are preferred. Nitriding provides high hardness and n,ear resistance and a lo\+ friction coefficient.
Chemical Composition. AISI: Nominal. 0.75 C (other carbon contents may be available), 4.00 Cr. 1.00 V, 18.00 W. AISI/UNS (T12001): Composition: 0.45 to 0.55 C. 0.15 to 0.10 hln. 0.30 Ni max. 3.75 to 4.50 Cr. 4.50 to 5.50 MO. 0.75 to I.25 V. 5.50 to 6.75 I+ Similar
Steels (U.S. and/or Foreign). AMS 5626: ASTM A600: FED QQ-T-590; SAE J437. J438; (Ger.) DIN I .3355: (Fr.) AFNOR 2 80 WCV 18-04-01.3548 265 WDCV 6.05; (Ital.) UN1 X 75 W 18 KU; (Jap.) JIS SKH 2; (U.K.) B.S. BTI Characteristics. Has been the standard 18--I-l high-speed steel o\er the years. Available with several carbon content levels and has the advantage of high resistance to decarburiration. Rates very high in wear resrstance and in softening resistance at elevated temperature. Is similar to other high-speed steels in that it has low toughness when rated with tool steels in general. Using lower austenitizing temperatures. however, results in lower hardness and improved impact resistance Forging. Start forging at 1065 to I I7S “C ( 1950 to 2 I50 “F). Do not forge after temperature of forging stock drops below 955 “C t I750 “F)
Recommended Normalizing.
Heat Treating
Do not normalize
Practice
Annealing.
Heat to 870 to 900 “C ( I600 to I650 “F). Use lower limit for small sections and upper limit for large sections. Pack annealing in tightly closed containers or using a controlled atmosphere or vacuum is recommended to minimize decarburization. The packing material can be dry sand or lime to which a small amount of charcoal has been added. Burned cast iron chips are also satisfactory. Use a container that is only slightly larger than the load to mimmtze the amount of paching material required. This allows the pack to heat rapidly. After the steel has reached the annealing temperature. it should be held at temperature for I h per inch of thickness of the container Cool slowly in furnace to 650 “C t I200 “F) at a rate not to exceed 22 “C t-t0 “F) per h. after which a faster cooling rate will not affect tinal hardness. Typical annealed hardness. 2 I7 to 255 HB
Relieving. Optional. Heat to 650 to 675 “C t 1200 to 1245 OF) and hold for I h per inch of cross section (minimum of I h). Cool in air
Stress
Hardening. Preheat at 8 IS to 870 ‘C t IS00 to I600 “F). Double preheating in one furnace at 540 to 650 “C t 1000 to I200 “F) and in another at 845 to 870 “C t, IS55 to 1600 “F) will minimize thermal shock. Preheating time, after all sections of the tool have reached equal temperature. should be twice the length of time required at the austenitizinp temperature. Heat rapidly from preheating to austenitizing temperature. Heat rapidly from preheating to austenitizing temperature. Austenitize at 1260 to 1300 “C (2300 to 2375 “F) for 2 to 5 min. Use I-1 “C i2S “F) lower when hardening
Tool Steels / 623 from salt. When high carbon material is involved. lower the austenitizing temperature I-! “C (25 “F) in addition to the reduction when hardenincg from salt bath. Use shorter time for small sections and longer time for l.arge sections. Quench in oil. air. or salt. As-quenched hardness. 61 to 66 HRC
l
Stabilizing.
l
Recommended l l
Optional. For intricate shapes. stress relieve temper at I.50 to 160 “C (300 to 320 “F) brietly. Refrigerate at -100 to -19s “C r-150 to -370 “F). Temper immediately after part reaches room temperature
l l l
Tempering. Temper al 540 10 595 “C ( IO00 10 II05 “F) for at least 2 h. cool 10 room temperature. and retemper for two more hours. Approximate tempered hardness as it corresponds to tempering temperature. 64 to 60 HRC
l l
Processing
Sequence
Rough machine Stress relieve (optional) Finish machine Prehsat Austenitize Quench Stabilize (optional1 Temper Final grind to size
Tl: Isothermal Transformation Diagram. Tl containing 0.72 C. 0.27 Mn, 0.39 Si, 4.09 Cr, 1.25 V, 18.59 W. Austenitized at 1290 “C (2350 “F)
Tl : Transformation of Retained Austenite. Effect of room-temperature aging on the transformation range of retained austenite in hardened Tl during cooling to -190 “C (-310 “F)
Tl : Hardness vs Austenitizing Time and Temperature. Sample was 9.525 mm (?/8 in.) round by 9.525 mm (3/s in.), brine quenched, and austenitized in a salt bath. Source: Teledyne VASCO
624 / Heat Treaters
Guide
Tl : Nitrided Microhardness Gradients. 0: nitrided in aged bath 90 min, 0: nitrided in aged bath 180 min. A: nitrided in aged bath 360 min. A: nitrided in new bath 90 min. Sbecimens nitrided at 565 “C (iO50 “F). Dotted lines are projected’to surface hardness of other samples given same time in bath. A has surface sample nitrided 300 min
Tl: Hardness vs Time and Tempering Temperature. Austenitized at 1290 “C (2355 “F) and tempered at the temperatures indicated
Tl: Nitriding (1050°F)
Time vs Nitrogen
Content.
Nitrided at 565 “C
Tool Steels / 625
Tl: Retained Austenite Transformation vs Subcooling Temperatures. Effect of room-temperature aging stabilization on the transformation of retained austenite on hardened Tl when subcooled to different temperatures. Note that the longer the holding time at room temperature, the less austenite decomposition is accomplished by a given cold treatment. Austenitized at 1290 “C (2355 “F)
Tl: Hardness vs Time and Tempering Temperature. Oil quenched from 1290 “C (2355 “F). Time and tempering temperature needed to produce maxrmum secondary hardness and complete transformation of austenite. Specimen size, 12.7 by 12.7 by 15.875 mm (0.50 by 0.50 by 0.625 in.)
Tl: Carbon Penetration (1695”F)for8h
in Carburizing.
Tl : Hardness vs Tempering and quenched from 1205 “C 1315 “C (2400 “F). Tempering by 25.4 by 19.05 mm (1.75 by loys Steel
Carburized
at 925 “C
Temperature. Tl containing 0.70 C (2200 “F), 1260 “C (2300 “F), and time, 2 l/z h. Specimen size, 44.45 1 by 0.75 in.). Source: Vanadium-Al-
626 / Heat Treaters
Guide
Tl: Carburized Microstructures.
Tl microstructure across the carburized zone. Carburized 8 h at 955 “C (1750 “F). oil quenched from 1205 “C (2200 “F), and tempered 2 l/2 h at 565 “C (1050 “F). (a) 0.00 mm (0.00 in.). (b) 0.914 mm (0.036 in.). (c) 0.305 mm (0.012 in.). (d) 1.168 mm (0.046 in.). (e) 0.559 mm (0.022 in.). (f) 1.829 mm (0.072 in.). Source: Teledyne VASCO
Tl: Microstructures.
(a) 2% nital, 1000x. As received (mill annealed). Large and small spheroidal carbide particles in matrix of ferrite. See (b) and (c). (b) 10% nital, 1000x. Austenitized 3 to 4 min at 1280 “C (2335 “F), salt quenched to 605 “C (1125 “F). air cooled. Undissolved carbide particles in untempered martensite. See (c). (c) 4% nital, 1000x. Austenitized and salt quenched same as (b), then double tempered at 540 “C (1000 “F). Undissolved carbide particles in matrix of tempered martensite
Tool Steels / 627
Tl: Microstructures. (a) 200 nital. 1000~. As received (mill annealed). Large and small spheroidal carbide particles in matrix of ferrite. See (b) and (c). (b) loo0 nital. 1000x. Austenitized 3 to 4 min at 1280 C (2335 ’ F), salt quenched to 605 C (1125 ‘-F). air cooled. Undissolved carbide particles in untempered martensite. See (c). (c) 4’0 nital. 1000x. Austenitized and salt quenched same as(b). then double tempered at 540 “C (1000 ‘F). Undissolved carbide particles in matrix of tempered martensite
Tool Steels / 627
T2 Chemical
COInpOSitiOn. AM: Nominal. 0.80 C. 1.00 Cr. 2.00 V. 18.00 %‘. AISl/UNS (T12002): Composition: 0.80 to 0.90 C. 0.30 to O.-IO Mn. 0.30 to 0.10 Si. 0.030 Ni max. 3.75 to 4.50 Cr. 1.00 MO max. 1.80 to 3.40 v. 17.50 to 19.00 w
Similar
Steels (U.S. and/or Foreign). ASTM ~600; FED QQ-T590; SAE J337. J438; (Fr.) AFNOR A35590 -1201 CV 1%M-01, -I303 18-O-Z; (U.K.) B.S. 4659 BTI. 4659 BT2. -1659 BT20
Characteristics. This 18--!-Z grade has slightly better wear resistance and hot hardness than the TI grade and rates very high in both categories. It is suitable for chip removal and many other applications. Is similar to other high-speed steels. having low toughness m hen rated against other tool steels in general. Using a louer austenitizing temperature. however. results in lower hardness and improved impact resistance. Has medium machinability
Strew Relieving. Optional. Heat to 650 to 675 “C ( I200 to I245 “Fj and hold for I h per inch of cross section (minimum of I h). Cool in air
Hardening.
Preheat at 8 IS to 870 “C ( I SO0to 1600 “FJ. Double preheating in one furnace at 540 to 650 “C ( 1000 to I XXI “Fj and in another at 845 to 870 “C ( IS55 to I600 “F) will minimize thermal shock. Preheating time. after all sections of the tool have reached equal temperature. should he twice the length of time required at the austenitizing temperature. Heat rapidly from the preheating to the austenitizing temperature. Austenitize at I260 to I300 “C (2300 to 2375 “F) for 3 to 5 min. Use I-l “C (25 “F) lower when hardening from salt. Use shorter time for small sections and longer time for large sections. Tools austenitized at the lower end of the temperature range will have greater toughness. when compared to tools austenitized at the upper end of the range where greater alloy solution serves to impart higher hardness and hot hardness in service. Quench in oil, air, or salt. As-quenched hardness. 65 to 67 HRC
Start forging at 1065 to I I75 “C (1950 to 2150 “F). Do not forge after temperature of forging stock drops helow 955 ‘C ( 1750 “F)
Stabilizing. Optional. For intricate shapes, stress relieve temper at I50 to I60 “C f 300 to 370 “FI briefly. Refrigerate at - 100 to - I95 “C (-I 50 to -370 “F). Temper immediately after part reaches room temperature
Recommended
Tempering.
Forging.
Normalizing.
Heat Treating
Practice
Do not normalize
Annealing. Heat to 870 to 900 “C ( 1600 to 1650 “F). Use Ion er limit for small sections and upper limit for large sections. Pack annealing in tightly closed containers or using a controlled atmosphere or vacuum is recommended to minimize decarburization. The packing material can be dry sand or lime to which a small amount of charcoal has heen added. Burned caSt iron chips are also satisfactory. Use a container that is only slightly larger than the load to minimize the amount of paching material required. This allows the pack to heat rapidI>. After the steel has reached the annealing temperature. it should he held at temperature for I h per inch of thickness of the container. Cool slowly in furnace to 650 “C ( IX0 “F) at a rate not to exceed 22 “C (-10 “Fj per h. after which a faster cooline rate will not affect final hardness. Typical annealed hardness. 713 to 3-55 HB
Temper at 540 to 595 “C ( 1000 to I I05 “Fj for at least 2 h, cool to room temperature. and retemper for two more hours. Approximate tempered hardness as it corresponds to tempering temperature, 66 to 61 HRC
Recommended l l l l l l l l l
Processing
Sequence
Rouph machine Stress relieve (optional) Finish machine Preheat Austenitize Quench Stabilize (optional) Temper Final grind to size
T2: Hardness vs Time and Tempering Temperature. Relationship between time and tempering temperature required to produce maximum secondary hardness and complete the transformation of austenite. T2 containing 4 Cr. 2 V, 18 W was oil quenched from 1290 “C (2355 “F). Source: Teledyne VASCO
628 / Heat Treaters
Guide
T2: Isothermal
Transformation
Diagram.
Containing 0.85 C. 4.00 Cr. 0.75 MO, 2.10 V. 18.50 W. Austenitized at 1290 “C (2355 “F). Source: Crucible Steel
Tool Steels / 629
T2: Hardness vs Time and Tempering Temperature. Relationship between time and tempering temperature required to produce maximum secondary hardness and complete the transformation of austenlte. T2 containing 4 Cr. 2 V. 18 W was oil quenched from 1290 “C (2355 “F). Source: Teledyne VASCO
Tool Steels / 629
T4 Stress k?hhIg. Optional. Heat to 650 to 675 “C (I 200 to I X5 “Fj and hold for I h per inch of cross section (minimum of I h). Cool in air
Chemical
COIIIpOSitiOn. AISI: Nominul. 0.75 C. 4.00 Cr. I.00 V. I8.00 IV. 5.00 Co. AISl/UNS (T1200-Q: Composition: 0.70 to 0.80 C. 0. IO to 0.10 hln. 0.X to 0.10 Si, 0.30 Ni maa. 3.75 to 3.50 Cr. O.-IO to I .OO hlo. 0.80 to I .70 v. 17.50 to 19.00 IV. 4.7-s 10 5.75 Co
Hardening. Preheat at 8 IS to X70 ‘C f I SO0 to 1600 “F). Double preheating In one furnace at S-IO to 6SO ‘YI t 1000 to 1200 “Fj and in another at 845 to 870 “C I IS55 to 1600 ‘F) u ill mimmize thermal shock. Preheating time. after all sections of the tool have reached equal temperature. should be twice the length of time required at the austenitizing temperature. Heat rapidly from the preheating to the aubtenitizing temperature. Austenitize at 1260 to I300 “C (2300 to 2375 “F) for 1 to 5 min. Use l-l “C (35 “Fj lower u hen hardening from salt. Llse shorter time for small sections and longer time for large sections. Tools austenitized at the lower end of the temperature range \\ ill hale greater toughness. when compared to tools austenitized at the upper end of the ranps where greater alloy solution serves to impart higher hardness and hot hardness in service. Quench in oil. air. or salt. As-quenched hardness. 63 to 66 HRC
Similar Steels (U.S. and/or Foreign). ASTM x600; FED QQ-TSW: SAE J137. J-t?& (Ger.) DIN 1.3755: tFr.) AFNOR A35590 1’71 Z 80 LVKC 1%OS-M-0.1. AX-590 1375 Z 80 IVKCV 1%IO-M-O’: (Ital.) UNI X 78 WC-o 1805 KU: (Jap.) JIS G-1103 SKH 3: c’Ll.K., B.S. -I659 BT-I Characteristics. EssentialI> a Tl grade with SC, cobalt added. Joins the other cobalt-bearing high-speed grades in having the highest rating among tool steels in resistance to softening at elevated temperature. Is particularly suited for hsavy cutting difficult-machining alloys. Simile to other high-speed steels in having relatively IOU toughness u hen comp‘ared to tool steels in general. Use of lower austenitizmg temperature. housver. results in loner hardness and improved impact resistance. Has \eg high wear resistance. medium machinahilit). and medium decarhurizntion restslance
Stabilizing. Optional. For intricate shapes. stress relieve temper at IS0 to I60 ‘YY r?OfJ to 320 “F) hrisfl!. Refriperate at -100 to -195 “C (-IS0 to -310 “F). Temper immcdiatelv after part reaches room temperature
Forging.
Start forgln_g at 1065 to I I75 ‘C 11950 to 2150 “Fj. Do not forge after temperature of foraging stock drops hclo~ 955 ‘YI ( I750 “FI
Recommended Normalizing.
Heat Treating
Tempering.
Temper at 540 to cwl slouI> in furnace to room formed martensite from causing t\\o mow hours. Furnace cooling temper ib henetizial. .Approximate temprtring tsmp?rature. 66 to 62
Practice
Do not normalize
Annealing. Heat to X70 to 900 “C I 1600 to I650 “FJ. Use lower limit for small sections and upper limit for large >ectlon>. Pack annealing in trehtlb IS recomclosed containers or usmg a controlled atmosphere or VXUUIII mended to minimize decarhuriration. The packing material can be dq hand or lime to H hich a small amount of charcoal has been added. Burned cast won chip5 are also satlsfactorq. Use a container that 1s onl! sliphtl) larscr than the load to timmire the amount of packing matenal required. Thus allows the pack to heat rapidI!.
T4: Isothermal Transformation austenitized
at 1290 “C (2355 OF)
Recommended l l l l l l l l l
S9S “C t 1000 to II05 “Fj for at least 2 h. temperature to prevent the freshly transcracking of intricate tools. Retemper for not necessar?,: tools can cool in air. A third tempered hardnes\ as it corresponds to HRC
Processing
Rough machine Stress relieve (optional) Finish machine Preheat Austenitize Quench Stabilize Ioptional) Temper Final grind to size
Diagram. A British grade of T4,
Sequence
630 / Heat Treaters
Guide
T4: Isothermal Transformation
Diagram. T4 containing 0.72 C. 0.23 Mn, 0.43 Si, 4.04 Cr, 1.24 V, 18.38 W, 4.72 Co. Austenitized at 1290 “C (2350
T4: Hardness vs Tempering Temperature. Austenitized “C (2355 “F)
at 1290
Tool Steels I631
(a) 2% nital. 1000x. As received (mill annealed). Large and small particles of carbide (white and gray pools) in a matrix of ferrite. See (b) and (c). (b) 10% nital, 1000x. Austenitized at 1290 “C (2355 “F) for 3 to 4 min, quenched in salt to 605 “C (1125 “F), and air cooled. Undissolved carbide particles (large and small pools) in a matrix of untempered martensite. See (c). (c) 4% nital, 1000x. Austenitized and salt quenched as for (b), then double tempered at 540 “C (1000 “F). Undissolved particles of carbide (white) in a matrix of tempered martensite T4: Microstructures.
Tool Steels I631
Chemical
Composition. AISI: Nominal. 0.80 C. 4.00 Cr. 2.00 V. 18.00 W, 8.OOC.o. AISI/UNS (TlZOOS): Composirion: 0.75 too.85 C.O.20 too.40 Mn.0.20100.40 Si. 0.30 Ni max. 3.75 to 5.OOCr. 0.50 to I.25 MO. I .80 to 2.10 V, 17.50 to 19.00 W. 7.00 to 9.50 Co
Similar Steels (U.S. and/or Foreign). ASTM ~600; FED QQ-T590; SAE J437. J438; (Ger.) DW 1.3365; (Fr.) AFNOR A35-590 4275 Z 80 WKCV 18-10-04-02; iltal.) 1JNI X 80 WCo 1810 KU: (Jap.) JIS G-I-103 SKH 1: (Swed.) SS (LISATS): (U.K.) B.S. 4659 BTS Characteristics.
An 18-4-2 pade with an 84, cobalt addition thal imparts extreme resistance to softening at elevated temperatures. Rales among the highest in softening resistance and. in common with other cobalt-bearing high-speed grades. is very suitable for heavy chip removal and difficult machining tasks. Has very high wear resistance, low to medium machinability, and low decarburization resistance
Forging.
Start forging at 1065 to I I75 “C ( 1950 to 2 I50 “FL Do not forge after temperature of forging stock drops below 980 “C ( I795 “F)
Recommended Normalizing.
Heat Treating
Practice
Do not normalize
allows the pacb to heal rapidly. .After the steel has reached the annealing temperature. it should be held at lrmpernture for I h per inch of thickness of the container. Cool slo\\ ly in furnace to 650 “C t I200 “F) at a rate not to exceed 22 “C (40 “Fj per h. after u hich a Fdster cooling rate will not affect final hardness. Typical annealed hardness. 235 to 385 HB Stress Relieving. Optional. Heat to 650 io 675 ‘T I 1200 to 12.45 “F) and hold ior I h per inch of cross section (minimum of I h). Cool in air
Hardening. Preheat at 8 I5 to 870 “C ( I500 to 1600 “F). Double preheating in one timace at S-IO to 650 “C I 1000 to I200 “F) and in another at 845 to 870 ‘C (I555 to 1600 “F) \\ill minimize thermal shock. Preheating time. after all sections of the tool ha\e reached equal Iemperature. should be t\\ice the length of time required at the austenitizinp temperature. Heat rapidI) from the preheating to the austenilizing temperature. Austenitizs at 1275 to 1300 “C (2325 to 2375 “FJ for 2 to 5 min. Use II “C (25 “F) loner ~4hen hardening from salt. Use shorter time for small sections and longer time for large sections. Tools austenitized at the loner end of the lemperature range u ill have greater toughness. u hen compared to tools austenilized at the upper end of the range u here greater alloy solution serves to impart higher h‘ardncss and hot hardness in service. Quench in oil. air. or salt. As-quenched hardness. 6-l to 66 HRC Stabilizing. OptIonal. For lntncate shapes. stress relieve temper at IS0 to IhO “C (300 to 320 ‘FI brietl). Rsfngerate at -100 to -194 “C (-150 10 -320 “FL Temper immediately after part reaches room temperature
Annealing.
Heat to 870 to 900 “C ( 1600 to I650 “FL I!se lo\rsr limit for small sections and upper limit for large sections. Pack annealing in tightI> closed conminers or using a controlled atmosphere or vacuum is recommended to minimize decarbunration. The packing matenal can be drq sand or lime to which a small amount of ch‘arcoal has been added. Burned cast iron chips are also satisfactor). Use a container that is onI> 4ightlj larger than the load to minimtrr the amount of packing malsrial required. This
Tempering. Temper at S-10 to cool 4o\\I) in furnace to room formed martensite from causing tuo more hours, Furnace cooling Approximate tempered hardness ture. 65 to 60 HRC
595 “C t I000 LO I IO5 “F) for at least 2 h. temperature to prevent the freshly uanscmckmg of intricate tools. Retemper for not necessary; tools can be cooled in air. a\ it corresponds to tempering Irmpera-
632 / Heat Treaters
Recommended l l l l l l l l l
Guide
Processing
Rough machinz Stress relieve (optional
Sequence
1
Finish machine Preheat Austenitire Quench Stabilize Ioptional, Temper Finn1 grind Lo Gre
T5: Microstructures. (a) 2?& nital, 1000x. As received (mill annealed). Large and small spheroidal particles of carbide in a matrix of ferrite. Compare with structures in (b) and (c). (b) 10% nital, 1000x. Austenitized 3 to 4 min at 1280 “C (2335 “F), salt quenched to 605 “C (1125 “F), aircooled. Undissolved carbide particles (large and small pools ) in a matrix of untempered martensite. See (c). (c)4% nital. 1000x. Austenitized and salt quenched same as (b), then double tempered at 540 “C (1000 “F). Undissolved particles in a matrix of tempered martensite
632 / Heat Treaters
Guide
T6 Chemical Composition. AISI: Nominal. 0.80 C. -1.50 Cr. I.50 V. 0.75 to 0.85 C. 10.00 W. 12.00 Co. AlSl/UNS (TL?OO-S): Composition: 0.20 to 0.40 Mn. 0.20 to 0.40 Si. 0.30 Ni max. 4.00 to 4.75 Cr. 0.40 to I .OO hlo I50 to 2.10 V, 18.50 to 21.00 \v. Il.00 to 13.00 Co
ing temperature reduces hardness and improLes impact resistance. to medium mnchinahility and lo\v decarhuriration resistance
Similar
Recommended
Steels (U.S. and/or
QQ-T-590(T-6):tGer.)DIN 4659 BTh
Foreign). ASTM A600 1.3~57:rJap.)JlSG-1103SKH-IB:(l~.K.~
(T-6):
FED B.S.
Forging. Start forging at I065 to I I75 “C t I950 to 2150 “FL Do not forge after temperature of forging >toch drops helou 980 “C t 1795 “FJ
Normalizing. Annealing.
Characteristics.
An ultrahiph-allay high-speed steel. containing 20% tunpsten and I?? cohnlt. With other cobalt-containing high-speed steels. rated highest m resistance to softemnp at elevated temperature. Has LST) high wear resistance and is particularI) suitnhle for hew)-feed chip removal on difiicult machininp matrrinls. such as superallo)s. Has a IOU toughness rating when compared to tool s~cels in general and falls heIon the median in toughness among high-bpesd steels. lke of lower austenitiz-
Has low
Heat Treating
Practice
Do not nomlalizs
Heat to 870 to YOO”C I 1600 to 1650 OF). Use lower limit for small section% and upper limit for large sectIons. Pack annealing in tight11 closed containers or using ;1 controlled atmosphere or vacuum is recommended to minimize decnrburizntion. The packing material can be dry sand or lime to u hich a small amount of charcoal has heen added. Burned cast Iron chips are also satisfactoq. Clse 3 container that is onl) slightly larger than the load to minimize the amount of packing material required. This nllo\rs the pack to heat rapidly. After the steel has reached the annealing
Tool Steels / 633
temperature, II should he held a~ temperature for I h per inch of thickness of the container. Cool slowly in furnace to 650 “C ( I NO “F) at a rate not to exceed 22 “C (JO “F) per h. afier which a faster cooling rate \rill not affect final hardness. Typical annealed hardness. Z-18 to 30’ HB StreSS k?lieVing. Optional. Heat to 650 to 675 “C I 1200 to IX ‘FI and hold for I h per inch of cross section (minimum of I h). Cool in air
Hardening. Preheat at 8 IS to 870 “C ( I SO0 to I600 “F). Double preheatinp in one furnace at S-IO to 650 “C t IO00 to I200 “F) and in another at 8-U to 870 “C (I 555 to I600 ‘F) will minimize thermal shock. Preheating time. after all sectlons of the tool have reached equal temperature. should he twice the length of time required at the nustenitizing temperature. Heat rapidly from the preheating to the austenitizing temperature. Austenitize at 1275 to 1300 “C (3325 to 2375 OF) for 3 to 5 min. Use I-l “C (25 “F) lower when hardening from salt. Use shorter time for small sections and longer time for large sections. Tools austenitized at the lober end of the temperature range H ill have greater toughness. when compared to tools austenitized at the upper end of the ranpe where greater alloy solution serves to impart higher hardness and hot hardness in service. Quench in oil, air. or salt. As-quenched hardness. 63 to 66 HRC
Stabilizing. Optional. For mtricate shapes, stress relieve temper at IS0 to 160 “C (300 to 3X OF) briefly. Refrigerate at -100 to -195 “C (-150 to -310 “F). Temper immediately after part reaches room temperature Tempering. Temper at S-IO to cool slo\vl> in timace to room formed martensite from causing two more hours. Furnace cooling temper is required. Approximate tempering temperature, 65 to 60
Recommended l l l l l l l l l
S9S “C t 1000 to I IO5 “F) for at least 7 h. temperature to prevent the freshly transcracking of intricate tools. Retemper for is not necessary; cool tools in air. A third tempered hardness as it corresponds to HRC
Processing
Sequence
Rough machine Stress relieve (optional) Finish machine Preheat ?-\ustcnitize Quench Stabilize (optional) Temper Final grind to size
T6: Hardness
vs Time and Tempering
ship between the tempering time and the required to produce maximum secondary the transformation of retained austenite. 1.75 V. 20.00 W. 12.00 Co. Oil quenched
Temperature.
Relationtempering temperature hardness and complete T6 containing 4.00 Cr, from 1295 “C (2360 “F)
634 / Heat Treaters
T6: Microstructures.
Guide
(a) 2% nital, 1000x. As received (mill annealed). Particles of carbide (small white pools and large gray pools) in a matrix of ferrite. The quenched and tempered microstructure is shown in (b). (b) 4% nital. 1000x. Austenitized at 1290 “C (2355 “F) for 3 to 4 min. quenched in salt to 605 “C (1125 “F), air cooled, and double tempered at 540 “C (1000 “F). Large and small particles of carbide (white) in a matrix of tempered martensite
634 / Heat Treaters
Guide
Chemical
COIIIpOSitiOn. AISI: Nominal. 0.75 C. 4.00 Cr. 2.00 V, l-l.00 W. S.OOCo. AISI/UNS (T12008): Composition: 0.75 IO 0.85 C. 0.20 to 0.30 hln. 0.20 to 0.40 Si. 0.30 Ni mas. 3.75 to 4.50 Cr. O.-IO IO I .OO hlo. 1.80 to 2.40 V. 13.3-S to l-l.75 W, 1.25 to 5.75 Co
Similar
Steels (U.S.
and/Or
Foreign).
ASTM
.4600: FED QQ-T-
590; SAE 5437, J-138
Characteristics.
Tungsten is the principal alloying element: Sci, cohah is added for hot hardness. Along with the other cobalt-bearing high-speed steels. rates highest among tool steels in resistance to softening at elevated temperature. Has very high wear resistance and is suitable for heav) chip removal on difficult machining alloys. Rates low in toughness. as do other high-speed steels. Use of lower austenitiring temperatures results in lower hardness and improved impact resistance. Has medium machinabilit> and medium decarburization resistance
Forging.
Start forging at 1065 to I I75 ‘Y’ ( 1950 to 2 IS0 “FL Do not forge after temperature of forging stock drops helou 955 “C t 1750 “F)
Recommended Normalizing. Annealing.
Heat Treating
Practice
Do not normalize
Heat to 870 to 900 “C t I600 to I650 “F). Use loner limit for small sections and upper limit for large sections. Pack annealing in tightly closed containers or using a controlled atmosphere or vacuum is recommended to minimize decarburization. The packing material can be dq sand or lime to which a small amount of charcoal has been added. Burned cast uon chips are also satisfactory. Use a container that is onI4 slightly larger than the load to minimize the amount of packing material required. This allows the pack to heat rapidly. After the steel has reached the annealing temperature, it should be held at temperature for I h per inch of thickness of the container. Cool slowly in furnace to 650 C t I200 “R at a rate not to exceed 22 “C (40 “F) per h. after which a faster cooling rate will not affect final hardness. Typical annealed hardness. 229 to 255 HB
Stress RelieVing. Optional. Heat lo 650 to 675 “C (I200 to I250 “F) and hold for I h per inch of cross section (minimum of I h). Cool in air
Hardening. Preheat at 8 IS to 870 ‘:‘C ( I SO0 to 1600 “FJ. Double preheating in one furnace at S-10 to 650 “C t IO00 to 1200 “F) and in another at MS to 870 “C t I SSS to I600 “FJ u ill minimize thermal shock. Preheating time. after all sections of the tool have reached equal temperature. should be twice the lsngth of time required at the austenitizing temperature. Heat rapidly from the preheatincg. IO the austenitiring temperature. Austenitize at I260 to I300 “C (2300 IO 2375 ‘F) for 2 to S min. Use I-I “C (25 “F) lower when hardening from salt. Use shorter time for small sections and longer time for large sections. Tools austsnitized at the lower end of the temperature range will have greater toughness. when compared to tools austenitized at the upper end of the range \v here greater alloy solution serves to impart higher hardness and hot hardness in service. Quench in oil. air. or salt. As-quenched hardness, 6-1 IO 66 HRC Stabilizing. Optional. For intricate shapes. stress relieve temper at IS0 to 160 “C (300 to 320 “F) briefly. Refrigerate at -100 to -195 “C (-150 to -320 “F). Temper immediateI!, after part reaches room temperature Tempering. Temper at 5-W to 595 “C t 1000 to I IO5 “Fj for at least 2 h. cool slo~ilj in furnace to room temperature to prevent the freshly transfomled martensite from causing cracking of intricate tools. Retemper for two more hours. Furnace cooling is not necessq; cool tools in air. Approsimnte hardness. 65 to 60 HRC
Recommended l l l l l l l l l
Processing
Rough machine Stress relieve (optional) Finish machine Preheat Austcnitire Quench Stnhilize toptionnl) Temper Final grind IO size
Sequence
Tool Steels / 635
Tl5 Chemical
COmpOSitiOn. AISI: Nomrnal. I SO C. 1.00 Cr. 5.00 V. I2.00 W. SOOCo. AISl/UNS (T12015): Composition: I SO to I .60 C. 0. IS to 0.40 Mn. 0.15 to 0.10 Si, 0.30 Ni max. 3.75 to 5.00 Cr. I.00 MO max. 3.50 to 5.25 v. I I.75 to 13.00 w. 4.75 to 5.25 co
Similar
Steels (U.S. and/Or
Foreign).
590: (Ger.) DIN 1.3202; (Fr.) AFNOR II!-OS-OS-M; (Ital.) UN1 X I50 WCoV TIS); (U.K.) B.S. 4659 BTIS
ASTM A600: FED QQ-TA3S-590 4171 Z 160 WKCV 130505 KU: (Shed.) SS (USA
Characteristics. Has both the highest carbon ( 1.5%) and vanadium content (5%) of the high-speed steels. Similar to grade M-l. is rated highest m wear resistance among tool steels. including erosion at service temperature. Is particularly suitable for heavy chip removal on difficult-machining alloys. Toughness is low. Using low austenitizing temperatures results in lower hardness and improved impact resistance. Has low to medium machinability and medium decarburiration resistance Forging.
Start forging at 1065 IO I I75 “C (I950 to 2 IS0 OF). Do not forge after temperature of forging stock drops below 980 “C ( I795 “Fj
Recommended Normalizing. Annealing.
Heat Treating Practice
Do not normalize
Heat to 870 to 900 “C ( I600 to I650 “F). Use lower limit for small sections and upper limit for large sections. Pack annealing in tightly closed containers or using a controlled atmosphere or vacuum IS recommended to minimize decarburization. The packing material can be dry sand or lime to which a small amount of charcoal has been added. Burned cast iron chips are also satisfactory. Use a container that is only slightly larger than the load to minimize the amount of packing material required. This allows the pack to heat rapidly. After the steel has reached the annealing temperature. it should be held at temperature for I h per inch of thickness
of the container. Cool slowly in furnace to 650 “C ( 1200 “F) at a rate not to exceed 22 “C (-IO “F) per h. after which a faster cooling rate will not affect Final hardness. Typical annealed hardness. 231 to 277 HB Stress RdieVing. Optional. Heat to 6S0 to 675 “C ( I200 to I24 “Fj and hold for I h per inch of cross section (minimum of I h). Cool in air
Hardening. Preheat at 8 IS to 870 “C ( I500 to 1600 “F). Double preheating in one furnace at 510 to 650 “C ( 1000 to I200 “F) and in another at 835 to 870 “C ( 15% to 1600 “F) will minimize thermal shock. Preheating time. after all sections of the tool have reached equal temperature, should be twice the length of time required at the austenitizing temperature. Heat rapidly from the preheating to the austenitizing temperature. Austenitize at I205 to I260 “C (2200 to 2300 “F) for 2 to 5 min. Use I4 “C (25 “Fj lower when hardening from salt. Use shorter time for small sections and longer time for large sections. Tools austenitized at the lower end of the temperature range will have greater toughness. when compared to tools austenitized at the upper end of the range where greater alloy solution serves to impart higher hardness and hot hardness in service. Quench in oil. air, or salt. As-quenched hardness. 65 to 68 HRC Stabilizing. Optional. For intrtcate shapes. stress relieve temper at IS0 to 160 ‘C (300 to 320 OF) briefly. Refrigerate at -100 to -195 “C (-150 to -320 “F). Temper immediately after pan reaches room temperature Tempering.
Temper at 540 to 650 ‘C (1000 to I200 “F) for at least 2 h, cool slow Ig in furnace to room temperature to prevent the freshly formed martensite from causing cracking of intricate tools. Retemper for two more hours. Furnace cooling is not necessary; cool tools in air. A third temper is required. Approximate tempered hardness as it corresponds to tempering temperature. 68 to 63 HRC
636 / Heat Treaters
Recommended l l l l
Guide
Processing
Sequence
l l
Rough machine Stress relieve Finish machine Preheat
l l l
r\ustenitir~ Quench Stabilize (optrenal) Temper Final grind to six
T15: Hardness vs Austenitizing and Tempering Temperature. Austenitized at 1245 “C (2275 “F), 1220 “C (2225 “F) and 1120 “C (2050 “F) and double tempered (2 h plus 2 h)
T15: Hardness vs Time and Tempering Temperature. Austenitized at 1245 “C (2275 “F) and tempered at times and temperatures indicated
T15: Hardness vs Tempering Temperature. 1245 “C (2275 “F). Source: Teledyne VASCO
115: Unnotched ROD Impact Values. All specimens were austenitized at 1245 “C (2275 “F) in salt for 5 min at heat, oil quenched, triple tempered to hardness for 2 h plus 2 h plus 2 h and air cooled. Source: Carpenter Technology Corporation
Austenitized
at
Tool Steels / 637
T15: Carburized Case Hardness. After four different carburizing treatments: (a) 3 h at 900 “C (1650 “F), plus 20 min at 1065 “C (1950 “F) and oil quenched; (b) 3 h at 900 “C (1650 “F), plus 40 mm at 1065 “C (1950 OF) and oil quenched; (c) 30 min at 815 to 845 “C (1500 to 1555 “F), plus 20 min at 1065 “C (1950 “F) and oil quenched; (d) 30 min at 815 to 845 “C (1500 to 1555 “F), plus 40 min at 1065 “C (1950 “F) and oil quenched. Source: Teledyne VASCO
T15: Microstructures. (a) 6% nital. 500x. As cast. 76 mm (3 in.) diam disk, 13 mm (0.50 in.) thick. Dark areas are self-tempered martensite and chromium-rich M2&; light areas are alloy-rich austenite-carbide eutectic. Fan-shape particles are primary M,C; irregular globules are vanadium-rich MC. (b) 4% nital, 1000x. Austenitized at 1230 “C (2245 “F) for 3 to 4 min, quenched in salt to 605 “C (1125 “F), aircooled, and triple tempered at 540 “C (1000 “F). Undissolved particles of carbide in a matrix of tempered martensite. (c) 5% nital, 500x. Annealed at 900 “C (1650 “F), austenitized in salt at 1220 “C (2225 “F), salt quenched at 595 “C (1105 “F), triple tempered at 595 “C (1105 “F). Dark is tempered martensite, secondary M,C. Light is remnants of austenite-carbide eutectic. primary M,C. White globules are MC
638 / Heat Treaters
Guide
T15: Isothermal Transformation Diagram. Specimens were austenitized at 1260 “C (2300 “F). Source: Carpenter Technology Corporation
Molybdenum
High-Speed
Tool Steels
(M Series) Introduction hlolyhdenum high-speed 1001 steels are used primarily for cu11inp tools. Normalizing these steels is not recommended. However. [he hl series steels must he fully annealed after forging or when rehardening is required. The details of annealing are explained for each of the he1steels on the following pages The hl series steels. in common w ith the T series. are always preheated prior lo austenitizing to enable equalizatton of expansion in various sections of the 1001 and to minimize stresses that might occur because of the transformation to austenite at approximately 760 “C tl-LOO “F). Double preheating. as described helow. is oflen recommended to minimize thermal shock. If only a single preheat is used, preheat hlh at 790 C (1455 “F) and he1IS at 8 IS 10 870 ‘C i I SO0 to I600 “F). The remaining hl steels should he preheated at 730 to 815 “C f I350 to IS55 “F). Preheating time. after all sections of the 1001 have reached equal 1emperature. should be twce the length of time required a~ the austenitizing temperature. When preheating m two stages. longer time can he urilized at the fust s1age. S-IO to 650 ‘C t IO00 to 1200 “F). without incurring harmful effect, Only small tools and those that do no1 incorporate sharp notches or abrupt changes in section may he placed direc1ly into the austenitizing furnace with reasonable safely. To dissolve the various comples alloy carbides in the hq tool sleek 10 any appreciable extent during austenitizing, the steels must he heated to temperatures approaching their melting point For this reason. esceedingly accurate control is required in austenitizinp these steels. Steels con1aininp abou1 3%. or more vanadium may he held at the austenitizing tempera1ure about 50% longer than 1he lower vanadium types. The relatively pure vanadmm carhide phase inheren1 in the microstructure is virtually insoluble
at temperatures below the melting point and acts to restrict grain growth. pernutting longer soaking limes. However. the recommended austenuizing temperature for these steels should not he exceeded. Single point tools intended for heavy-duty cutting can be effectively ausrenitized at 8 to I7 “C t IS to 30 “F) above the nominal austenitizing [emperature to improve hot hardness and temper resistance. Fine-edged tools. such as taps and chasers. may he hardened at temperatures II to 28 “C (35 to SO ‘F) h&w the nominal austenitizing temperature to impart added toughness. Other adjustments in austenitizing temperature depend on the type of heating equipmen employed. as explained helow. Other variables are also noreworthy. Below I I75 “C (2150 “F). for example. hl2 steel cannot develop full hardness on quenching, because of insufficient carbide solution. At temperatures above approxtmately I230 “C (X-IS “F). the as-quenched hardness of M? decreases because of too much carbon and alloy solu1ion as well as an excess of retained austenite in the as-quenched steel. The hl series steels can he quenched in air. oil. or molten salt. Stahilizing may be used to transform retained austenite. The hardened or hardened and 1empered tool is cooled to at leas1 -85 “C t- I20 “F) and then tempered or re1empered at nomlal tempering temperatures. As noted in the data helow. the response to secondary hardening is also a factor in the selection of tempering temperature. The steelsmay he nitrided, preferahly in liquid nitriding baths. capable of producing a more ductile case wi1h a lower nitrogen content than tha1 normally obrarned in gaseous mtriding atmospheres. Nitriding provides high hardness and wear resistance and a low friction coefficient.
Ml Chemical
COmpOSitiOn. AISI: Nominal. 0.85 tent% nlav be wailable). 4.00 Cr. X.50 hlo. I .OO V. Composhion: 0.78 to 0.88 C. 0. IS to 0.10 hln. 0.20 to 3.50 to 4.00 Cr. 8.20 to 9.20 Mo. I .OO to I .3S \I. I.40
C (other carbon conI.50 W. AISI/UNS: 0.50 Si. 0.30 Ni mas. to 2. IO W
Recommended Normalizing.
Heat Treating
Practice
Do not normalize
Annealing.
Characteristics. Molybdenum is the principal alloying element in this. one of the leaner alloyed high-speed steels. It is as available as the popular M2 grade and costs less: the least expensive high-speed steel. Available in several carbon levels, and very suitable for chip forming tools. Rated very high in resistance to softening at elevated temperatures. and in resistance to wear. Low in toughness (as are other high-speed steels of comparable carbon content). and low in decarburization resistance
Heat to 8 IS to 870 “C ( I SO0 to 1600 “F). Use lower limit for small sections and upper limit for large sections. Pack annealing in tightly closed containers or usmg a controlled atmosphere or vacuum is required to minimize decarburization. The packing material can be dry sand or lime to which a small amount of charcoal has been added. Burned cast iron chips are also satisfactory. Use a container that is only slightly larger than the load to minimize the amount of packing material required. This allows the pack to heat rapidly. After the steel has reached the annealing temperature, it should be held at temperature for I h per inch of thickness of the container. Cool slowly in furnace to 650 “C t I200 OF) at a rate not to exceed 22 “C (-IO “F) per h. after which a faster cooling rate will not affect final hardness. Typical annealed hardness. 207 to 335 HB
Forging. Start forging at IO-IO to I IS0 “C t 1905 to 2100 “F). Do not forge after temperature of forging stock drops below 925 “C ( I695 “F)
Stress Relieving. Optional. Heat to 650 to 675 “C ( I200 to 1215 OF) and hold for I h per inch of cross section (minimum of I h). Cool in air
Similar Steels (U.S. and/or Foreign). ASTM A600 (M-l ): FED QQ-T-590 (M-l ): SAE 5437 (hll). .I138 (hll): (Ger.) DIN 1.3346: (Fr.) AFNOR A3S-590 44-t I Z 85 DCM?’ 08-01-02-01: (Ital.) 1JNI X 82 hloH’ 09 KU: (Swed.) SS 27 IS: (U.K.) B.S. 1659 BM I
640 / Heat Treaters
Guide
Hardening. Preheat at 730 to 8 IS “C i I350 to IS00 “Ft. Double preheating in one furnace at S-IO to 650 “C ( IO00 to I Xl “F) and in another at S-15 to 870 “C ( IS55 to I600 “F) will minimize themmal shock. Preheating time. after all sections of the tool have reached equal temperature. should be twice the length of time required at the austenitizing temperature. Heat rapidly from the preheating to the austenitizing temperature. Austcnitize at I I75 to 1220°C (I?150 to X35 “F) for 2 to 5 min. USC I-t “C t2S “F) lourr when hardening from salt. When high carbon material is imolved. loiter the austenitizing temperature l-t ‘C (7-S “F) in addition to the reduction when hardening from salt bath. Use shorter time for small sections and longer time for large sections. Tools austenitizcd at the lo\rer end of the temperature range uill have greater tou@ness, u hen compared to tools austenitized at the upper end of the range 1%here greater alloy solution serves to impart higher hardness and hot hardness. Quench in oil. air. nr salt. As-quenched hardness. 6-t to 66 HRC
Tempering. Temper at S-t0 to 595 “C t IO00 to I I OS “F) for at least 2 h. cool to room temperature. and retsmper for L? h. Approximate tempered hardness as it corresponds to tempering temperature, 65 to 60 HRC
Recommended l l l l l l l l l
Processing
Sequence
Rough machine Stre,s relic\ e (optional) Finish machine Preheat Austcnitize Quench Stabilize toptionalt Temper/double Final grind to size
Stabilizing. Opttonal. For intricate shapes. stress relieve tcmpsr at IS0 to I60 “C (300 to 320 “F) briefly. Refrigerate at -100 to -195 “C (-IS0 to -330 ‘F). Temper immediately after part reaches room temperature Ml : Effect of High-Carbon
High-Alloy
Surface Austenite
in Ml High-Speed
Steel on the Hardness
After Liquid
Nitriding
Specimens 12.7 mm (t/2 in.) long were cut from a treated bar, 9.525 by 31.75 by 101.6 mm ( 38 by 1 l b by 4 in.); bar hardened at 1225 “C (2240 “F) in 34 to 35% atmosphere and tempered for 1 h at 550 “C (1025 “F); before nitriding, 0.0152 mm (0.0006 in.) was removed from the treated exterior surfaces Nitriding time at Surfacecondition
HRA
HRC
zoo0
1000
hlicruhardness 500
I I 2
85 I as 0 85.0
66.0 660 66 0
MS 767 767
853 80 I x0 I
I I 3
8-l 1 8-l 5 81.5
6S.0 65 .O 65 0
IO20 I OS6 I OX6
1056 I104 110.4
Hardness,
10SO°F(-%50C).h
load, g 200
100
859 8’7 x2:
886 902 90’
827 827
IOSY I I.50 I I so
1116 I IS6 II56
Carhurized Nitridcd Ewrior wrtkr Noncarburbed Nitndrd Sectioned surfxe
Ml : Effect of Subzero Tempering Continuously OF
+8tJ I regular) -3 -so -100 -120
cooled to: “C +26 -32 46 -73 -8-l
Treatment
Increase volume.
0.3 0.28 0 3I 0 39
on Ml High-Speed
in F1,
Hardness. HRC 65 3 67.2 67.4 67.3 67.9
Steel After Hardening
Proportional ksi 91 130 I 3tr I 60 I 70
limit hlPa 617 890 Y% I III! II72
Ml : Hardness
Iii2 II32
at 1205 “C (2200 “F) With No Subsequent Torsionnl hlodulus li\i 236 -.75-l2-19 -.‘i7 766
propertie of rupture hlPa I627 1737 1717 I772 I?334
vs Austenitizing
in./in.
Plastic strain mm/mm
O.OI 7 0.009 0.007 O.(x)7 0007
and Tempering
Austenitizedat 1220°C (2225°F). 119O”C(2175”F), (2125 “F) and double tempered (2 h plus 2 h)
0 -132 0.229 0. I78 0.178 0. I78
Temperatures. and 1165°C
Tool Steels / 641
Ml: Hardness vs Tempering Temperature. Austenitized 1205”C(2200”F),1175”C(2150”F),and1150”C(2100”F)and double tempered. Source: Universal-Cyclops
at
Ml : Effect of Carbon Monoxide Atmosphere on Surface Carbon Content. Containing 0.80 C, 8.71 MO, 0.99 V, 1.80 W in an atmosphere of 23% carbon monoxide. Austenitized at 1205 “C (2200 “F) for 8 min
Ml : Hardness vs Time and Tempering Temperature. of time at tempering temperature on Ml, austenitized (2200 “F).
The effect at 1205 “C
Ml : Effect of Time on Surface Carbon Content. Treated in an atmosphere of 119/ocarbon monoxide. 0 represents Ml containing 8.67 MO, 1 .19 V, 1.61 W. 0 represents Ml containing 8.90 MO. 1.04 V. 1.42 W
Ml: Microstructures. (a) 296 nital, 1000x. Austenitized at 1150 “C (2100 “F), quenched in salt, double tempered (2 h plus 2 h) at 550 “C (1020 “F). Carbide particles in matrix of tempered martensite. See (b) and (c) for effects of lower and higher austenitizing temperatures. (b) 29/onital. 1000x. Given the same heat treatment as (a), except the austenitizing temperature was lower. 1120 “C (2050 “F). Carbide particles in matrix of tempered martensite. Excess of small particles caused by underheating. (c) 29’0 nital, 1000x. Given the same heat treatment as (a), except the austenitizing temperature was higher. 1220 “C (2225 “F). Some carbide is present in the matrix of tempered martensite. Higher austenitizing temperature dissolved most of the carbide
642 / Heat Treaters
Guide
M2 Chemical
Composition.
AISI: Nominal. 0.85 to I .OO C (other carmay be available). -1.00 Cr. 5.00 hlo. 1.00 V. 6.00 u’. AM/UNS: Composition: 0.78 to 0.88 C. 0.95 to I .OS C. 0. IS to O.-IO hln. 0.70to0.~5Si.0.30Nima~.3.75to-1.50Cr.~.75to6.50hlo.2.25to-7.75 V. 5.00 to 6.75 W bon contents
Similar
Steels (U.S. and/or Foreign).
Regular
Carbon Composition: ASTM 4600 (hl-2): FED QQ-T-590 (hl-2): SAE J-137 (hl?). 5338 tM2): (Ger.) DIN 1.33-11. 1.33-13. 1.33-lS. I .3553. I ,355-l: (Fr.) AFNOR A35590 -2301 Z 85 WDCV 06-OS-0102: (Ital.) UNI X 82 If’hlo 0605 KU; (Jap.) JIS G-1103 SKH 51. SKH 59; (Swcd.) SS 272: (U.K.) B.S. 4659 BMl. High Carbon Composition: (Ger.) DIN I .33-10. I .33-l?: (Fr.) AFNOR A3S-590 1302 Z 90 H’DCV 06-OS-O-l-01
Characteristics.
The most wideI\ used high-speed steel. A relatively low cost grade with the distinction 6f being a general all-purpose steel. Suitable for a multitude of applications and arailable upith setera carbon contents. Rates very high in resistance to wear and resistance to soheninp at elevated temperature. It rates low in toughness. but using a louer austenitizing temperature with the resulting slightly louer hardness improves its impact resistance. Has medium resistance to decarburization. Available in regular and high carbon compositions
Forging.
Stat forging at IWO to I IS0 “C ( I905 to 2100 “F). Do not forge after temperature of forging stoch drops below 915 “C ( I695 “F)
Recommended Normalizing. Annealing.
Heat Treating
Practice
Do not normalize
Heat to 870 to 900 ‘C ( 1600 to 1650 “F). Clse lower limit for small sections and upper limit for large sections. Pack annealing in tightly closed containers or using a controlled atmosphere or vacuum is required to minimize decarburization. The packing material can be dry sand or lime to ti hich a small amount ofcharcoal has been added. Burned cast iron chips are also satisfactory. Use a container that is only slightly larger than the load to minimize the amount of packing material required. This allows the pack to heat rapidly. After the steel has reached the annealing temperature. tt should be held at temperature ior I h per inch of thickness of the container. Cool slowly in furnace to 650 ‘C ( I200 OF) at a rate not to exceed 22 “C
(10 “F) per h. after which a faster cooling rate will not affect final hardness. Typical annealed hardness. 2 I ? to 2-l I HB
Stress Reiit?Ving. Optional. Heat to 650 to 675 “C ( I200 IO I%5 “F) and hold for I h per inch of cross section (minrmum of I h). Cool in air Hardening. Preheat at 730 to 8-15 “C ( I.350 to 1555 “F). Double preheating in one furnace at S-IO to 650 “C ( IO00 to I200 “F) and in another at 8-0 to 870 “C I IS55 to I600 “F) u ill minimize [hernial shock. Preheating time. after all secttons of the tool have reached equal temperature. should be (irice the length of time required at the austenrtizing temperature. Heat rapidly from the preheating to the austenitizing temperature. Austenitize at I I90 to 1230 “C (2 I75 to 22-U “FJ for 2 to 5 min. Use I-l “C (15 “F) lower when hardenmg from salt. When high carbon material is involved. lower the austenitizinp temperature 1-l “C (35 “F) in addition to the reduction when hardening from salt bath. Use shorter time for small sections and longer time for large sections Tools austznitized at the lower end of the temperature range will have greater toughness. when compared to tools austsnitized at the upper end of the range u here greater alloy solution serves to impart higher hardness and hot hardness. Quench in oil. air. or salt. As-quenched hardness. 61 to 66 HRC Stabilizing. Optional. For intricate shapes. stress relieve temper at I50 to I60 “C (300 to 320 “F) briefly. Refrigerate at -100 to -195 “C (-150 to -320 “F). Temper immediately after part reaches room temperature Tempering. Temper at S-IO IO 595 “C ( 1000 to I I OS “F) for at least 3 h. cool to room temperature. and retemper for 3 h. Approxmiate tempered hardness as it corresponds to tempering temperature. 65 to 60 HRC
Recommended l l l l l l l l l
Processing
Sequence
Rough machine Stress relic\ e (optional) Finish machine Preheat Austcnitizs Quench Stabilize (optional) Temper/double Final grind to size
M2: Isothermal Transformation
Diagram. Contains 0.81 C, 0.24
Mn.0.016P,0.007!3,0.26Si,4.10Cr,4.69Mo.
1.64V,5.95W
Tool Steels / 643
M2: Isothermal Transformation Diagram. Modified M2 containing0.83C.0.32Mn,0.25Si,3.89Cr.4.30Mo, 1.30 V, 5.79 W. Austenitized at 1220 “C (2225 “F). Prior condition, annealed
M2: Retained Austenite vs Tempering Time. Quenched from 1220 “C (2225 “F), to 105 “C (225 “F), and tempered at 565 “C (1050 “F)
M2: Hardness vs Time at Tempering Temperature. Austenitized at 1220 “C (2225 “F) and tempered at the times indicated
644 / Heat Treaters
Guide
M2: Retained Austenite vs Hardness. Quenched from 1220 “C (2225 “F) to 105 “C (225 “F), and tempered at indicated temperatures for 2 l/2 h
M2: Dimensional Change vs Tempering Temperature. A 19.05 mm (0.75 in.) round by 101.6 mm (4 in.) specimen of M2, quenched for 2 h from 1260 “C (2300 “F), 1230 “C (2245 “F), and 1205 “C (2200 “F)
12: Retained Austenite vs Quenching Bath Temperature. luenched from 1220 “C (2225 “F) to indicated temperatures and #ingle tempered at 565 “C (1050 “F) for 2 l.2 h bl2: Hardness Zyclops
vs Tempering
Temperature.
Source: Universal-
Tool Steels / 645
M2: Hardness vs Austenitizing and Tempering Conditions. (a) Austenitized at 1245 “C (2275 “F), 1230 “C (2245 “F), 1205 “C (2200 “F), and 1150 “C (2100 “F), and receiving single temper for 1 h. (b) Austenitized at 1230 “C (2245 “F), 1205 “C (2200 “F), and 1175 “C (2150 “F), and receiving single temper for 2 h. (c) Austenitized at 1230 “C (2245 “F), 1205 “C (2200 “F), and 1175 “C (2150 “F), and double temper (2 h plus 2 h). (d) Austenitized at 1225 “C (2240 “F), single temper at 480 “C (895 “F) and 565 “C (1050 “F)
M2: Microstructures.
(a) 3% nital, 1000x. 50.8 mm (2 in.) diam bar austenitized at 1220 “C (2225 “F), oil quenched, tempered at 550 “C (1020 “F) for 1 h. Spheroidal carbide particles in matrix of tempered martensite. Some small areas of retained austenite evident. (b) 6% nital, 750x. 22.23 mm (0.875 in.) diam bar, austenitized at 1260 “C (2300 “F), oil quenched. double tempered at 565 “C (1050 “F). Tempered martensite with a few spheroidal carbide particles. Incipient melting at grain boundaries resulted from overheating
(continued)
646 / Heat Treaters
Guide
M2: Microstructures
(continued). (a) 10% nital, 1000x. 22.23 mm (0.875 in.) diam bar, austenitized at 1165°C (2125 “F) and oil quenched. Spheroidal carbide particles in untempered martensite. ASTM grain size, 17. (b) 10% nital. 1000x. Same steel as (a), except austenitized at 1210 “C (2210 “F). ASTM grain size had increased to 12 because of higher austenitizing temperature. (c) 10% nital, 1000x. Same steel as (a), except austenitized at 1240 “C (2260 “F), resulting in a further increase in ASTM grain size to 8
M2: Hot Hardness of Regular Carbon Grade. Source: Carpenter Technology Corporation
Tool Steels / 647
M2: Hot Hardness of High Carbon Grade. Source: Carpenter Technology
Corporation
648 / Heat Treaters
M3 Class
Guide
1
Chemical Composition. AN: Nominal. I .OS C. 4.00 Cr. 5.00 MO. I .OO IO I. IO C. 0. IS to 0.40 hln. 2.10 V. 6.00 W. AISI/UNS: Composition: O.?OtoO.45 Si.0.30Ni max.3.75 to1.SOCr.4.75 to6.SOhlo. 1.7s 102.20 V. 5.50 to 6.75 W Similar
Steels (U.S. and/or Foreign). ASTM A600 t hl-3. Cl. I ): FED QQ-T-590 (hl-3): SAE 5437 ~M?J. J-138 (h13); (Ger., DIN 1.3342: (Fr.) AFNOR Z 90 WDCV 06-05-O-I-02: (Jap.) JIS G-l-IO3 SKH 51 Characteristics. Contains slightl! higher Lanadium and carbon content than M3 which gives it slightly higher resistance IO wear and resistance to softening at elevated temperatures. Toughness rating is also slightI> less than M2. but use of lower austenitizing temperature and the slightly lower hardness which results. improves its impact resistance. Has medium resistance to decarburization Forging. Start forging at 1010 to I I50 “C ( 1905 to 2 100 “F). Do not forge after temperature of forging stock drops belo\\ 925 “C t 16% “FJ
Recommended Normalizing. Annealing.
Heat Treating
Practice
Do not normalize
Heat to 870 to 900 ‘C ( 1600 to I650 “FL Use lo\rer limit for small sections and upper limit for large sections. Pack annealing in tightly closed containers or using a controlled atmosphere or vacuum is required to minimize decarbunzation. The packing material can be dQ sand or lime IO which a small amount ofcharcoal has been added. Burned cast iron chips are also satisfactory. Use a container that is onl! slightI> larger than the load to minimize the amount of packing material required. This allous the pack to heat rapidly. After the steel has reached the annealing temperature. it should be held at temperature for I h per inch of thickness of the container. Cool slow Iy in furnace to 650 “C ( I300 “F) at a rate not to eweed 22 “C (-IO “F) per h. after which a faster cooling rate u ill not affect final hardness. Typical annealed hardness. 223 to ?S5 HB
Stress RdieVing. Optional. Heat to 650 to 675 “C (I200 to 12.45 “F) and hold for I h per inch of cross sectlon iminimum of I h). Cool in air Hardening. Preheat a~ 730 to 845 “C I I350 to I555 “F). Douhle preheating in one furnace at 540 IO 650 ‘C t 1000 IO I200 “F) and in another at 815 to 870 ;C (I SS5 to I600 “FI will minmize thermal shock. Preheating time. after all secttons of the tool have reached equal temperature. should he twce the length of time rrqulred al the austenitizing temperature. Heat rapidly from the preheating to the austenitizmg temperature. Austenitizr at I205 to I230 “C (2200 to 2245 “F) for 2 to 5 min. Use I-l “C (25 “F) lower u hen hardentry from salt. Use shorwr tune for small sections and longer time for large section\. Tools austenitizsd at the loher end of the temperature range I\ ill ha\ e greater toughness. u hen compared to tools austrnitized at the upper end of the range where greater alloy solution serves to impart higher hardness and hot hardnsss. Quench in oil. air. or salt. As-quenched hardness. 6-l to 66 HRC Stabilizing. Optional. For intncatc shapes. stress relieve temper at IS0 to I60 “C (300 IO 320 “F) hrietl~. Rcfngerate at -100 to -195 “C t-150 to -320 “FL Temper ImmediateI> after part reacheb room temperature Tempering. Temper at 510 to 595 “C (IO00 to I IO5 “F) for at least 2 h. cool to room temperature. and retemper for 2 h. Approximate tempered hardnsbs as it corresponds to tempering temperature. 66 to 61 HRC
Recommended l l l l l l l l l
Processing
Sequence
Rough machine Stress relie\s ioptional) Finish machine Preheat Austenitize Quench Stabilize toptional) Temper/double Final grind to size
M3 Class 1: Hardness vs Tempering Temperature. Triple tempered after hardening at 1230 “C (2245 “F), 1220 “C (2225 “F), and 1205 “C (2200 “F). Source: Universal-Cyclops
Tool Steels / 649
M3 Class Chemical
2
Composition.
3.00 V. 6.00 W. AISI/UNS: 0.20to0.-15Si,0.30Nimax.3.75
AM: Nominal. I.10 C. 1.00 Cr. 5.00 hlo. Composition: I .I5 to I.25 C. 0. IS to O.-IO hln. to-!.SOCr.-l.75 to6.SOhlo.2.75 to3.75
L’. 5.00 to 6.75 \h
Similar
Steels (U.S. and/or Foreign).
ASTM A600 ihl-3. Cl.2~
FED QQ-T-590 (hl-3); SAE J-l.37 (M3). J-l38 (M3): (Ger.) DIN 1.33-U: (Fr.) AFNOR A3S-590 -l360 WDCV 06-05-O-I-03. A3S-590 -I?61 ZI 30 M’DCV OS-O-!-O-l. A3S-590 1-W ZIOO DC-WC’ 09-0-l-02-02: tJap.) JIS G-1413 SKH S2. G-MO3 SKH 53: (Swed., SS (LISA h13. class 2,
Characteristics. Detinitel> a more wear-resistant grade than hl2. Has greater amounts of carbon and vanadium than hI3-class I grade Its toughnebs will be correspondingly loner. but use of lower austenitizing tsmpsrature and the resulting slightly lower hardness improves its impact resistance. It is rated \ery high in resistance to sotirninp at elevated temperature. medium in machinability. and medium in resistance to dscarburization Forging. Start forging at IWO to I I SO “C I I905 to 2 100 “FI. Do not forge after temperature of forgmp stock drops beIon 925 “C t 1695 “F)
Recommended Normalizing.
Heat Treating
Practice
Do not normalize
Annealing.
Heat to 870 to 900 ‘C I 1600 to I6iO “F). LISS lo\rer limit for small sections and upper limit for I,arge sections. Pnck annealing in tightI> clobrd containers or using a controlled atmosphere or vacuum is required to minimize decarhurization. The packing material can he dr) sand or lime to u hich a small amount ofcharcoal has hesn added. Burned cast iron chips are also sntisfactov. Llse a container that is onlj slightly larger than the load IO minimize the amount of packing material required. This allows the pack to heat rapid&. After the steel has reached the annealing temperature. it should he held at temperature for I h per Inch of thickness of the contamer. Cool slowI> in furnace to 650 -C ( I200 “F) at a rate not to exceed 22 ‘:‘C 1’40 “F) per h. after w hich a faqtsr cooling rate will not affect final hardness. Typical annealed hardness. 223 to 255 HB
M3 Class 2: Hardness vs Tempering Temperature. Triple tempered after austenitizing at 1230 “C (2245 “F), 1220 “C (2225 “F), and 1205 “C (2200 “F). Source: Universal-Cyclops
Stress Relieving. Optional. Heat to 650 to 675 “C (I200 to 1245 “F) and hold for I h per inch of cross section (minimum of I h). Cool in air
Hardening. Preheat at 730 to 8 IS “C i I350 to I SO0 OF). Double preheatinp in one furnace at S-IO to 650 “C ( IO00 to I?00 “F) and in another at 845 to 870 “C ( IS55 to 1600 “F) \s ill minimize thermal shock. Preheating time. after all sections of the tool ha\e reached equal temperature, should be twice the length of time required at the austenitizing temperature. Heat rapidI> from the preheating to the uustcnitizing temperature. Austenitize at I705 to I230 “C (2200 to 1215 “F) for 2 to 5 min. Use I3 “C (35 “F) lower when hardening from salt. L!se shorter time for small sections and longer time for 1arg.e sections. Tools austenitized at the lower end of the temperature ranpe w III have greater toughness. when compared to tools austenitized at the upper end of the range \\ here greater alloy solution senes to impart higher hardness and hot hardness. Quench in oil. air. or salt. As-quenched hardness. 6-l to 66 HRC Stabilizing. Optional. For intricate shapes. stress relieve temper at IS0 to 160 tiC ~300 to 320 “F) hrietly. Refrigerate at -100 to -195 “C (-150 to -320 “F). Temper immsdiatslv after part reaches room temperature Tempering.
Temper at 510 to 595 “C t 1000 to I IO5 “F) for at least 2 h, cool to room temperature. and retemper for 2 h. Approximate tempered hardness as it corresponds to tempering temperature. 66 to 61 HRC
Recommended l l l l l l l l l
Processing
Sequence
Rouph machine Stress rslieYe (optional) Finish machine Preheat Austenitize Quench Stahilize (optional) Temprr/douhte Final grind io bize
M3 Class 2: Unnotched Impact Values of Class 2 Alloy. Specimens were austenitized 5 min at 1205 “C (2200 “F) in salt, oil quenched, then triple tempered (2 h each) to hardness, and air cooled. Source: Carpenter Technology Corporation
650 / Heat Treaters
Guide
M3 Class 2: Microstructures. (a) 2% nital, 500x. Austenitized at 1205 “C (2200 “F), quenched in a salt bath, double tempered (2 h plus 2 h) at 550 “C (1020 “F). Large and small alloy carbide particles (white) in tempered martensite. See (b). (b) 2% nital, 1000x. Same steel and heat treatment as (a), but shown at higher magnification. Large white areas in structure are vanadium carbide, which characterized this grade of high-speed tool steel. (c) 10% nital. 1000x. Austenitized at 1220 “C (2225 “F), quenched in a salt bath, double tempered at 550 “C (1020 “F). Large and small particles of alloy carbide in matrix of tempered martensite.
650 I Heat Treaters
Guide
ill4 Chemical COmpOSitiOn. AISI: Nominal. I .30 C. -I.00 Cr. 450 hlo. -1.00 V. 5.50 IV. AISI/UNS: Composition: I .2S to 1.40 C. 0.15 to O.-IO h4n. 0.20 to O.-IS Si. 0.30 Ni max. 3.75 to -1.75 Cr. -!.?I to 5.50 MO. 3.75 to 4.50 v. 5.3 to 6.50 H
t-IO “F) per h. after which a faster cooling rate will not affect final hardness. Typical annealed hardness. 223 to 255 HB
Similar Steels (U.S. and/or Foreign). .ASTM A600 (M-1): FED QQ-T-590fM-4): SAEJ-137 (M-t). J-t38 (hi-t): (Fr.) AFNOR A3S-5901361 Z I30 WDCV 06-OS-O-LO-t; (Jap.) JIS G-U03 SKH S-t: (Saed. t SS ‘782: (U.K. j B.S. 4659 BH-t
Hardening. Preheat at 730 to 845 “C ( I350 to IS55 “Ft. Double preheating in one furnace at S-10 to 6SO “C ( IO00 to I200 “F) and in another at 845 to 870 “C (1555 to 1600°F) \\ill mininuze themral shock. Preheating time. after all sections of the tool hake reached equal temperature. should be tuice the length of time requwed at the austenitizing temperature. Heat rapidly from the preheating to the austenitizing temperature. Austenitize at I205 to I 330 ‘C (3200 to 22-lS “F) for 2 to 5 nun. Use I1 “C (25 “FJ lower when hardemng from salt. Ltse shorter time for small sections and longer time for large sections. Tools austenitized at the lower end of the temperature range H ill have greater toughness. when compared to tools austenitized at the upper end of the range where greater alloy solution serves to impart higher hardness and hot hardness. Quench in oil. air. or salt. As-quenched hardness. 65 to 67 HRC
Characteristics. This grade contains the same amount of carbon and vanadium as the highest modifications of the popular h,l2 grade. Its carbon content is greater than I.258 and its vanadium content is greater than 3%. \rhich qualities it as a super high-speed steel. One of the most wear-resistant grades of high-speed steel. Its toughness is reduced correspondingly. but using lower austenitizing temperatures nith loiter resulting hardness helps to improve its impact resistance. Has high resistance to softening at elevated temperatures. low to medium machinability. and medium resistance to decarbunzation Forging.
Start forging at IO-10 to I IS0 “C (I905 to 2100 “FL Do not forge after temperature of forging stock drops belo\{ 925 “C ( I695 “F)
Recommended Normalizing. Annealing.
Heat Treating
Practice
Do not normalize
Heat to 870 to 900 “C t 1600 to 1650 ‘F). C!se lower limit for small sections and upper limit for large sections. Pack annealing m tightly closed containers or using a controlled atmosphere or vacuum is required to minimize decarburization. The packing material can be dry sand or lime tow hich a small amount ofcharcoal has been added. Burned cast iron chips are also satisfactory. Use a container that is only slightly larger than the load to minimize the amount of packing material requtred. This allows the pack to heat rapidly. After the steel has reached the annealing temperature. it should be held at temperature for I h per inch of thickness of the container, Cool slowly in furnace to 650 “C ( I200 “FJ at a rate not to exceed 22 “C
stress Relieving. Optional. Heat to 650 to 675 ‘;C ( I200 to 12-U “F) and hold for I h per inch of cross section (minimum of I h). Cool in air
Stabilizing. Optional. For intricate shapes. stress relieve temper at I SO to 160 “C (XXJ to 320 “‘FJ briefly. Refrigerate at -100 to -195 “C (-150 to -320 “Ft. Temper immediately after part reaches room temperature Tempering.
Temper at S-IO to 595 “C (1000 to I IO5 “F) for at least 2 h, cool to room temperature. and retemper for 2 h. Approximate tempered hardness. 66 to 61 HRC
Recommended l l l l l l l l l
Processing
Rough machine Stress relieve (optional) Finish machine Preheat Austenitizs Quench Stahilizc (optional J Temperldouhle Final grind to size
Sequence
Tool Steels / 651
M4: Hardness vs Tempering Temperature. Triple tempered, after austenitizing at 1205 “C (2200 “F) and 1220 “C (2225 “F). Source: Universal-Cyclops
M4: Hardness vs Time at Tempering tized at 1220 “C (2225 “F)
M4: Hardness vs Time and Tempering Temperature. Contains 1.25 C, 5.0 MO. 4.0 V. 6.0 W. Quenched in oil from 1215 “C (2220 “F)
M4: Hardness vs Austenitizing and Tempering Temperatures. Austenitized at 1230 “C (2245 “F) and 1175 “C (2150 “F) and double tempered (2 h plus 2 h)
M4: Typical Unnotched IZOD Impact penter Technology Corporation
Temperatures.
Properties.
Austeni-
Source: Car-
652 / Heat Treaters
Guide
M4: Microstructures. (a) 4% picral, 1000x. 13.1 mm (0.515 in.) diam rod, as received (mill annealed). light), other alloy carbide (small spheroids) in ferrite. (b) 4% picral, 1000x. Same steel and condition Some carbide particles are slightly elongated. Vanadium carbide impacts high abrasion resistance. diam bar, austenitized at 1210 “C (2210 “F), oil quenched, double tempered (2 h plus 2 h) at 545 “C angular particles of carbide in matrix of tempered martensite
Particles of vanadium carbide (large, as (a), except a longitudinal section. (c) 6% nital, 750x. 12.7 mm (0.50 in.) (1015 “F), air cooled. Spheroidal and
652 / Heat Treaters
Guide
M7 Chemical
Composition. AISI: Nominal. I .OO c. 4.00 Cr. 8.75 hlo. 1.00 V, I .7S H’. AISI/UNS: Composition: 0.97 to I .05 C. 0. IS to O.-IO hln. 0.20 to 0.55 Si. 0.30 Ni max. 3.50 to -I.()() Cr. 8.1-O to 9.20 hlo. I .7S to 2.25 v. I .-lo IO 2. IO V+ Similar Steels (U.S. and/or Foreign). ASTM A600 t hl-7): FED QQ-T-590 (M-7); (Ger.) DIN 1.?3-l8; (Fr.) AFNOR A35-590 44-E Z 100 DCH’V 09-04-02-O’: (Jap.) JIS G-l-IO3 SKH 58 Characteristics.
blolybdenum is the principal alloying element. which makes this an economical grade of high-speed steel. Very high resistance to wear and resistance to softening at elevated temperatures, Has a relatkely low toughness rating. as do most high-speed steels. but using a lower austenitizinp temperature results in lower h.ardness and imptwsd impact resistance. Has medium machinability and low decarburiration resistance
Forging.
Start forging at IO-IO to I IS0 ;C (19O.i to 2100 “FL Do not forge after temperature of forging stock drops belo\{ 93 “C ( 169s “FJ
Recommended Normalizing.
Heat Treating
Practice
Do not nomtalize
Annealing. Heat to 8 IS to 870 “C ( I500 to 1600 “F). Use lower limit for small sections and upper limit for large sections. Path annealing in tightly closed containers or using a controlled atmosphere or vacuum is required to minimize dccarburization. The packing material can be dry sand or lime to which a small amount of charcoal has been added. Burned cast iron chips are also satisfactory. Use a container that is only slightly larger than the load to minimize the amount of packing material required. This allows the pach IO heat rapidly. After the steel has reached the annealing temperature. it should be held at temperature for I h per mch of thickness of the container. Cool slowly in furnace to 650 ‘C t I700 “F) at a rate not IO sweed 22 “C (-IO “F) per h, after which a faster cooling rate mill not affect final hardness. Typical annealed hardness, 7-I7 to 255 HB
stress Relieving. Opttonal. Hen1 IO 650 to 675 ‘C ( 1200 to I315 “F) and hold for I h per inch of cross section (minimum of I h). Cool in air
Hardening. Preheat at 730 to 8 IS “C I I350 to I SO0 “F). Double preheating in one furnace at S-IO to 650 ‘C ( I000 to I200 “F) and in another at 845 to 870 ‘C t IS55 to I600 “F) \iill minimize thermal shock. Preheating time. after all sections of the tool have reached equal temperature. should be t\r ice the le.ngth of time requucd at the austcnitizing temperature. Heat rapidly from the prcheatm_g to the nustenitizing temperature. Austenitize at I I75 to I220 ‘C (2 I SO to 73 ‘F) for 2 to S min. Use I-l jC (25 “F) lower when hardening from salt. lrse shorter time for small sections and longer time for large sections. Tools austenitized at the loner end of the temperature range u ill ha\ e greater toughness. when compared to tools austenitized at the upper end of the range M here greater alloy solution serves to impart higher hardness and hot hardness. Quench in oil. air. or salt. As-quenched hardness. 6-l to 66 HRC Stabilizing. Optional. For intricate shapes. stress relieve temper at I50 to I60 ‘C t.300 to 320 “F) htislly. Refrigerate at -100 to -195 “C (-150 to -310 “FL Temper muttediately after part reaches room temperature Tempering.
Temper at S-10 to 595 “C t 1000 to II05 “FJ for at least 2 h. cool to room temperature. and retemper for 3- h. Approximate tempered hardness as 11 corresponds to tempering temperature. 66 to 61 HRC
Recommended l l l l l l l l l
Processing
Rough machine Stress relieve (optional) Finish machine Preheat Austenitize Quench Stabilize (opttonal) Temper/double Final grind to size
Sequence
Tool Steels / 653
M7: Microstructures. (a) 2% nital, 500x. Austenitized at 1260 “C (2300 “F), salt quenched, double tempered at 550 “C (1020 “F). Severely overheated structure shows reprecipitated carbide eutectic and grain-boundary carbide in matrix of coarse martensite. See (d). (b) 3% nital, 500x. Cast M7, annealed by austenitizing at 870 “C (1600 “F) for 4 h and furnace cooling to 150 “C (300 “F). Spheroidal particles of carbide within prior austenite grains, and a eutectic structure (white, lamellar) at grain boundaries. See (c). (c) 3% nital, 1000x. Same steel and heat treatment as (b), except shown at higher magnification. Grain-boundary eutectic is now clearly resolved. Fully annealed structure suitable for subsequent hardening treatment. (d) 6?,‘0nital, 750x. Decarburized M7. White layer of ferrite at surface contains carbide particles (spheroids) and oxide (black). (e) 6% nital, 750x. Carburized M7. White layer consists mainly of tempered martensite and retained austenite
M7: Hardness vs Time at Tempering tized at 1220 “C (2225 “F) and tempered
Temperature. Austenifor times shown
M7: Hardness vs Austenitizing and Tempering Temperatures. Austenitized at 1220 “C (2225 “F), 1205 “C (2200 “F), and 1175 “C (2150 “F) and double tempered (2 h plus 2 h)
654 / Heat Treaters
Guide
M7: Hardness vs Tempering Temperature. Austenitized at 1220 “C (2225 “F), 1205 “C (2200 “F), and 1190 “C (2175 “F) and double tempered. Source: Universal-Cyclops
654 / Heat Treaters
Guide
Ml0 Chemical COIIIpOSitiOn. AISI: Nominal. 0.85 to I .OO C (other carhon comerus may be available), 4.00 Cr. 8.00 MO. 2.00 V. AISI/UNS: Composition: 0.84 to 0.94 C, 0.95 to I .05 C. 0. IO to 0.10 Mn. 0.20 to 0.15 Si. 0.30 Ni max. 3.75 to 4.50 Cr. 7.75 to 8.50 MO. I.80 IO 2.20 V Similar
Steels (U.S. and/or Foreign).
FED QQ-T-590 (M-IO). carbon compositions
No similar
or foreign
ASTM ~600 (M-IO); steels for regular or high
Characteristics.
Molybdenum is the principal alloying element making this an economical grade of high-speed steel. Available in several levels of carbon content. Very high resistance to wear and softening at elevated temperature. Has a relatively low toughness rating as do most high-speed steels. but using a lower austenitizing temperature results in lower hardness and improved impact resistance. Medium machinability and low decarburization resistance. Available in regular and high carbon compositions
Forging. Start forging al IO-IO LO I I50 “C ( 1905 LO 3 100 “F). Do not forge after temperature of forging stock drops below 925 “C ( I695 “FJ
Recommended Normalizing.
Heat Treating
Practice
Do not normalize
Annealing. Heat to 8 I5 to 870 “C ( IS00 to 1600 “F). Use lower limit for small sections and upper limit for large sections. Pack annealing in tightly closed containers or using a controlled atmosphere or vacuum is required to minimize decarburization. The packing material can be dry sand or lime to which a small amount ofcharcoal has been added. Burned cask iron chips are also satisfactory. Use a container that is only slightly larger than the load to minimize the amount of packing material required. This allows the pack to heat rapidly. After the steel has reached the annealing temperature. it should be held at temperature for I h per inch of thickness of the container Cool slowly in furnace to 650 “C (I 200 “F) at a rate not to exceed 23 “C (40 OF) per h, after which a faster cooling rate will not affect final hardness. Typical annealed hardness. 207 to 255 HB
Stress Relieving. Optional. Heat to 650 to 675 “C ( 1200 to 1245 “F) and hold for I h per inch of cross section (minimum of I h). Cool in air Hardening.
Preheat at 730 to 815 “C ( I350 to IS55 “F). Double preheating in one furnace at 540 to 650 “C ( IO00 to I200 “F) and in another at 845 IO 870 “C (I 555 to 1600 “F) will minimize thermal shock. Preheating time. after all sections of the tool have reached equal temperature. should be twice the length of lime required at the austenitizing temperature. Heat rapidly from the preheating to the austenitizing temperature. Austenitize at I I75 to I/20-“C (2 I50 to 2225 “F) for 2 to 5 min. Use I4 “C (25 “F) lower when hardening from salt. When high carbon material is involved. lower the austenitizing temperature I-l “C (25 ‘F) in addition LO the reduction when hardening from salt bath. Use shorter time for small secnons and longer time for large sections, Tools austenitized at the lower end of the lemperature range will have greater toughness, when compared to tools austeninzed at rhe upper end of the range where greater alloy solution serves to impart higher hardness and hot hardness. Quench in oil, air. or salt. As-quenched hardness. 6110 66 HRC
Stabilizing. Optional. For intncate shapes. stress relieve temper at 150 to 160 “C (300 to 320 “F) briefly. Refrigerate at -100 to -195 “C (-150 to -320 “F). Temper immediately after pan reaches room temperature Tempering.
Temper at 510 to 595 “C ( 1000 IO I I05 “F) for at least 2 h. cool to room temperature. and retemper for 2 h. Approximate tempered hardness as it corresponds to tempering temperature. 65 IO 60 HRC
Recommended l l l l l l l l l
Processing
Rough machine Stress relieve (optional) Finish machine Preheat Austenitize Quench Stabilize (optional) Temper/double Final grind to size
Sequence
Tool Steels
Ml 0: Hardness vs Time and Tempering Temperature. Austenitized at 1205 “C (2200 “F) and tempered for times indicated
MlO: Hardness 122O”C(2225”F), double tempered
vs Tempering Temperature. Austenitized 1190”C(2175”F),and1165”C(2125”F)and (2 h plus 2 h)
/ 655
at
MlO: Isothermal Transformation Diagram. Contains 0.85 C. 4.0 Cr, 8.0 MO, 1.90 V. Austenitized at 1220 “C (2225 “F). Source: Crucible Steel
656 / Heat Treaters
Guide
MlO: Surface Carbon Content vs Time at Temperature. The effect of time at 1205 “C (2200 “F) on the surface carbon content of Ml 0 containing 2.26 V and 8.28 MO. Treated in 11% carbon monoxide atmosphere
MlO: Surface Carbon Content. Ml 0 containing 0.87 C, 2.13 V, 8.20 MO. Held at 1205 “C (2200 “F) for 6 min in an atmosphere of 23% carbon monoxide
WO: Hardness vs Time at Tempering Temperature. 3 MO, 4 Cr, 2 V. Oil quenched from 1215 “C (2220 “F)
MlO: Hardness vs Tempering Temperature. Austenitized 1205”C(2200”F),1175”C(2150”F),and1150”C(2100”F)and double tempered. Source: Universal-Cyclops
Contains
at
Tool Steels / 657
MlO: Nitriding Time vs Nitrogen Content. Nitrided at 565 “C (1050 “F). Effect of nitriding time on the nitrogen content of the surface layers of 0.000 to 0.025 mm (0.000 to 0.001 in.) and 0.025 to 0.050 mm (0.001 to 0.002 in.)
MlO: Microstructure. 6% nital. 750x. 12.7 mm (0.50 in.) diam bar, austenitized at 1175 “C (2150 “F), oil quenched, double tempered (2 h plus 2 h) at 565 “C (1050 “F). Spheroidal, angular, and rod-shape carbide particles in tempered martensite
Tool Steels / 657
ii30 Chemical
Composition. AISI: Nominal. 0.80 C. 4.00 Cr. 8.00 nlo. I .2S V. 2.00 IV. 5.00 Co. AISI/UNS: Composition: 0.75 to 0.85 C. 0. IS to 0.10 Mn, 0.30 to 0.15 Si. 0.30 Ni mak. 3.50 to 4.25 Cr. 7.75 to 9.00 hlo. 1.00 to I.40 v. 1.30 to 2.30 IV. 4.50 to S.SOC0 Similar
Steels
FED QQ-T-590
(U.S. and/or thl-30):
~600 (hl-30): Foreign). ASThl tGer.) DIN 1.324Y; (U.K.) B.S. 1659 Bhl3-l
Characteristics.
A r&ti\ely economical Spi cobalt grade which has molj hdenum as the prirwpal nllo~in@ element. One of the high-speed steels rating highest in resistance to sotteninp at elevated temperature. Has a IOU toughnw rating among tool steels in general as do other high-speed steels: usin! a Iowr austrnitiring temperature results in lower hardness and improved Impact resistance Verl high in Uear resistance. has medium machinahilit>. and IOU dscarhuriration resistance
658 / Heat Treaters
Guide
Forging. Start forging at 1040 to I IS0 “C ( 1905 to 2 100 “FL Do not forge after temperature of forging stock drops below 925 “C I 1695 “Fj
Recommended Normalizing.
Heat Treating
rapidly from the preheating to the austenitizing temperature. Austenitize at 1205 to 1230 “C t2200 to X-IS “F) for 2 to 5 min. Use I-l “C (25 “F) lower N hen hardening from salt.. Use shorter time for small sections and longer time for large sections. Tools austenitizcd at the lower end of the temperature range \i ill ha\ e greater toughness. when compared to tools austenitized at the upper end of the range where greater alloy solution serves to impart higher hardness and hot hardness. Quench in oil. air. or salt. As-quenched hardness. 61 to 66 HRC
Practice
Do not normalize
Annealing.
Heat to 870 to 900 “C I I600 to I650 OF). Use lower limit for small sections and upper limit for large sections. Pack annealing in tightI> closed containers or using a controlled atmosphere or vacuum is required to minimize decarburization. The packing material can be dry Sand or lime to which a small amount of charcoal has been added. Burned cast iron chips are also satisfactory. Use a container that is only slightly larger than the load to minimize the amount of packing material required. This allohs the pack to heat rapidly. After the steel has reached the annealing temperature. it should be held at temperature for I h per inch of thickness of the container. Cool slowly in furnace to 650 “C ( I NO “F) at a rate not to exceed 22 “‘C (40 “Fj per h. after which a faster cooling rate N ill not affect final hardness. Typical annealed hardness. 235 to 269 HB
Stress
Optional. Heat 10 650 to 675 “C t I200 to INS “F) and hold for I h per inch of cross section (minimum of I h). Cool in air RelieVing.
Stabilizing. Optional. For intricate shapes. stress relieve temper at IS0 to 160 “C (300 to 320 “F) briefI>. Refrigerate at -100 to -195 ‘C (-150 to -320 “F). Temper immediatel) alier part reaches room temperature Tempering. Temper at 510 to SYS “C t IO00 to I I OS “F) for at least 2 h. cool to room temperature. and retemper for 2 h. Approximate tempered hardness as it corresponds to tempenng vmperature. 65 to 60 HRC
Recommended l l l l
Hardening.
Preheat at 730 to 845 “C t I350 to 1555 “F). Double preheating in one furnace at S-IO to 650 >C ( IO00 to IX0 “FJ and in another at 815 to 870 “C (IS55 to 1600 “F) will minimize thermal shock. Preheating time. after all sections of the tool have reached equal temperature. should be twice the length of time required at the austenitizing temperature. Heat
l l l l l
Processing
Sequence
Rough machine Stress relieve (optional’) Finish machine Preheat Austenitize Quench Stahilizc (optional) Temper/double Final gnnd to size
M30: Hardness vs Tempering Temperature. Austenitized 1205”C(22OO”F).
double tempered.
1175”C(2150”F),and Source: Universal-Cyclops
1150%(2100”F)and
at
658 / Heat Treaters
Guide
ii33 Chemical
Composition. AISI: Nominal. 0.90 C. -t.OO Cr. 9.50 Mo. I. IS V, I.50 W. 8.00 Co. AISI/UTVS: Composition: 0.85 to 0.92 C. 0. IS to O.-l0 Mn. 0.15 to 0.50 Si. 0.30 Ni max. 3.50 IO 4.00 Cr. 9.00 IO 10.00 MO. 1.00 to I.35 V. 1.30 to 2.10 W. 7.75 to 8.75 Co
Similar
Steels (U.S. and/or
FED QQ-T-590
Characteristics.
(M-33):
(Ger.) DfN
Foreign).
t hl-33); A600 ASTM 1.32-l9: (U.K.) B.S. -t659 Bh13-l
This grade contains 85 cobalt and ranks highest among high-speed steels in resistance to softening at elevated temperature. as do other grades containing 8 or 12% cobalt. The principal alloying element is molybdenum. which makes it relatively economical for the hot hardness properties it provides. Very high resistance. Has a IOU toughness
rating among tool steels in general. as do other high-speed steels. Using a lower austenitirinp temperature. however. results in lower hardness and improved impact resistance. Has medium machinability and low decarburization resistance
Forging.
Stm forging at 1010 to I I50 “C I I905 to 2 100 OF). Do not forge after temperature of forging stoch drops helow 925 “C t 1695 “F)
Recommended Normalizing.
Heat Treating
Practice
Do not nomlalize
Annealing. Heat IO 870 to 900 “C t 1600 to 1650 “F). Use lower limit for small sections and upper limit for large sections. Pack annealing in tightly
Tool Steels / 659 closed containers or using a controlled atmosphere or vacuum is required to minimize decarburization. The packing material can be dry sand or lime to H hich a small amount ofcharcoal has been added. Burned cast iron chips are also satisfactory. Use a container that is only slightly larger than the load to minimize the amount of packing material required. This allows the pack to heat rapidly. After the steel has reached the annealing temperature. it should be held at temperature for I h per inch of thickness of the container. Cool slowly in furnace to 650 “C t 1200 “F) at a rate not to exceed 72 “C f-t0 “F) per h. after which a faster cooling rate will not affect final hardness. Typical annealed hardness, 235 to 269 HB
Stress Relieving. Optional. Heat to 650 to 675 “C t I200 to I Z-15 “F) and hold for I h per inch of cross section tminimum of I h). Cool in air Hardening.
Preheat at 730 to 845 “C i I350 to I555 “F). Double preheating in one furnace at S-10 to 650 “C ( 1000 to 1200 “F) and in another at 815 to 870 “C (IS55 to 1600 OF) will minimize thermal shock. Preheating time. after all sections of the tool have reached equal temperature. should be twice the length of time required at the austenitizing temperature. Heat rapidly from the preheating to the austenitizing temperature. Austenitize at 1305 to I330 “C (LX0 to 224.5 “F) for 2 to 5 min. Use II “C (35 “F) lower when hardening from salt. Use shorter time for small sections and longer time for large sections. Tools austenitized at the louer end of the tempera-
lure range will have greater toughness. when compared to tools austenitized at the upper end of the range where greater alloy solution serves to impart higher hardness and hot hardness. Quench in oil, air. or salt. Asquenched hardness. 64 to 66 HRC
Stabilizing.
Optional. For intricate shapes. stress relieve temper at I50 to 160 “C (300 to 320 “F) briefly. Refrigerate at -100 to -195 “C (-150 to -370 “F). Temper immediatelv after part reaches room temperature
Tempering. Temper at 540 to 595 “C (IO00 to I I05 “F) for at least 2 h. cool to room temperature. and retemper for 2 h. Approximate tempered hardness as it corresponds to tempering temperature, 65 to 60 HRC
Recommended l l l l l l l l l
Processing
Sequence
Rough machine Stress relieve (optional) Finish machine Preheat Austenitize Quench Stabilize ioptional) Temper/double Final grind to size
M33: Hardness vs Tempering Temperature. Austenitized at 1190 “C (2175 “F) and 1205 “C (2200 “F) and double tempered. Source: Universal-Cyclops
Tool Steels / 659
M34 Composition. AISI: Nominal. 0.90 C. -LOO Cr. 8.00 Mo. 2.00 V. X0 W. 8.00 Co. AISI/UNS: Composition: 0.85 to 0.92 C. 0. I5 IO 0.40 Mn. 0.10 to 0.45 Si. 0.30 Ni max. 3%) to 4.00 Cr. 7.75 to 9.20 hlo. 1.90 to -7.30 v. I.40 to 1. IO w. 7.75 10 8.75 co
hardness and improved impact resistance. low decarburization resistance
Similar
Recommended
Chemical
Steels (U.S. and/or Foreign).
FED QQ-T-590
(M-34):
A600 (hl-34): ASTM (Ger.) DIN 1.3249: (U.K.1 B.S. -I659 BM3-l
Characteristics. This grade contains 85, cobalt and ranks highest among high-speed steels in resistance to softening at elevated temperature as do the other grades containing 8 and I? c cobalt. The principal alloying element is molybdenum, which makes it relatively economical for the hot hardness properties it provides. Very high wear resistance. Has a lovv toughness rating among tool steels in general. as do the other high-speed steels. However. using a lower austenitizing temperature results in lower
Has medium machinability
and
Forging. Start forging at IO-&O to I IS0 “C (1905 to 7,100 “F). Do not forge after temperature of forging stock drops below 925 “C. (1695 “F)
Normalizing.
Heat Treating
Practice
Do not normalize
Annealing. Heat to 870 to 900 “C ( I600 to 1650 “F). Use lower limit for small sections and upper limit for large sections. Pack annealing in tightly closed containers or using a controlled atmosphere or vacuum is required to minimize decarburization. The packing material can be dry sand or lime to vvhich a small amount of charcoal has been added. Burned cast iron chips are also satisfactory. Use a container that is only slightly larger than the load to minimtze the amount of packing material required. This allows the pack
660 / Heat Treaters
Guide
to heat rapidlq. After the steel has reached the annealing temperature. it should be held at temperature for I h per inch of thickness of the container. Cool slog ly in furnace to 650 “C ( I200 “F) at a rate not to exceed 22 “C (10 “F) per h. after which a faster cooling rate will not affect tinul hardnesb. Typical annealed hardness. 235 to 269 HB stress RelieVing. Optional. Heat to 650 to 675 “C ( I ZOO IO I ?-IS “F) and hold for I h per inch of cross section (minimum of I h). Cool in air
Hardening. Preheat at 730 to 815 jC ( I350 to IS00 “F). Double preheating in one furnace at S-IO to 650 “C ( IO00 to I X0 ‘“Fj and in another a1815 to 870 “C ( 1555 to 1600 “F) will minimize thermal shock. Preheating time. after all sections of the tool have reached equal temperature. should be twice the length of time required at the austenitizing temperature. Heat rapidly from the preheating to the austrnitizinp temperature. Austsnitize at I205 to 1230 “C (2300 to 2NS “Fi for 2 IO 5 min. Use I-l “C 125 “F) lower when hardening from salt. Use shorter time for small sections and longer time for large sections. Tools austenitized a~ the lo\\er end of the tempcraturc range u ill ha\e _greatcr toughness. u hen compared to tools nustenitized at the upper end of the range M here greater allo) solution senses to impart M&l:
Hardness
vs Tempering
Temperature.
1190 “C (2175 “F) and 1205 “C (2200 Source: Universal-Cyclops
Austenitized at “F) and double tempered.
higher hardness and hot hardness. Quench in oil. au. or salt. As-quenched hardness. 6-l to 66 HRC
Stabilizing. Optional. For mtricnte shapes. stress relieve temper at 1.50 to I60 “C (300 to 320 “F) brie@ Refrigerate at -100 to -195 “C (-150 to -320 “F). Temper immediateI> after part reaches room temperature Tempering. Temper at S-10 to 595 “C ( IO00 to I IO5 “F) for at least :! h. cool IO room temperature. and retsniper for 2 h. Approximate tempered hardness as it corresponds to tempering temperature. 65 to 60 HRC
Recommended l l l l l l l l l
Processing
Sequence
Rough machine Stress relicw roptional) Finish machine Preheat Austenilizc Quench Stabilize roptional) Trtmper/doublz Final grind to size
M34: Hardness
vs Austenitizing
Austenitized at 1230 “C (2245 “C (2150 “F). Double tempered
M34: Hardness
and Tempering “F), 1205 “C (2200 (2 h plus 2 h)
vs Time and Tempering
tized at 1210 “C (2210 peratures indicated
“F) and tempered
Temperature. “F), and 1175
Temperature. at the times
Austeniand tem-
Tool Steels / 661
M35 Chemical
Composition.
AISI/UNS
(T11335):
0.82 to 0.88 C. 0. I5
to 0.10 Mn. 0.20 to 0.45 Si. 0.30 Ni max. 3.75 to 4.50 Cr. 4.50 IO 5.50 hlo. 1.75 to 2.20 v, 5.50 to 6.75 w. 4.50 to 5.50 co
Similar
Steels (U.S. and/or Foreign). GM) DIN 1.33-U; (Fr.) AFNOR A35-590137 I Z 85 WDKCV [email protected] Z90 IVDKC 06-05-05-01; tJap.) JIS G-I-103 SKH 55: (U.K.) B.S. 1659 BM34
Tool Steels / 661
ii36 Chemical
Composition. AISI: Nommal. 0.80 C. 1.00 Cr. 5.00 hlo. 2.00 V. 6.00 W. 8.00 Co. AISI/I!NS: Composition. 0.80 to 0.90 C. 0. IS to 0.40 hln. 0.X to 0.15 Si. 0.30 Ni max. 3.75 to -I.50 Cr. -I.50 to SSO hlo.
Stress Relieving. Optional. Heat IO 650 to 675 “C ( IX0 to IX5 OF) and hold for I h per inch of cross section (minimum of I h). Cool in au
1.75 to 2.25 I’. 5.50 to 6.50 W. 7.75 to 8.75 Co
Hardening. Preheat at 730 to 815 jC ( I350 to 15% “Ft. Double preheating in one furnace at 5-W to 650 ‘C ( 1000 to I700 “F) and in another at 815 to 870 “C ( IS55 to 1600 “F) will minimize thermal shock. Preheating time. alter 1111sections of the tool have reached equal temperature. should he twice the length of time requtred at the austcnitizing temperature. Heal rapidly from the preheating to the austenitizing temperature. Austenitize at IX) to I ?-IS ‘C (2225 to 277s “Ft for 7 to 5 min. Use I-1 “C (25 “F) lower M hen hardening from salt. Ltse shorter time for small sections and longer time for laqc secttons. Tools austenitized at the lower end of the temperature range ~6ill ha\e greater toughness. \t hen compared to tools austenitized at the upper end of the range where greater alloy solution serves to impart higher hardness and hot hardness. Quench in oil. air, or salt. As-quenched hardness. 6-I to 66 HRC
Similar
Steels (U.S. and/or Foreign). ASThl A600 (hl-36): FED QQ-T-590 (hl-36): (Ger.) DfN I .32-t?: tFr.r AFNOR AX-590 137 I Z 85 M’DYCV Oh-OS-05-04: (Jap.) JIS G1403 SKH SS: (Susd.t SS 272.3 Characteristics. This grade has the popular Ml analy,i> ~iith 8ci cobalt added. This addition imparts much greater resistance to softening at elevated temperatures. and it ranbs among the highest of the high-speed grades in this propeq. Wear resistance is \ery high. Has a lo\\ toughness rating among tool steels in general. as do the other high-speed steels. However. using a lower austenitizing temperature results in lobier hardness and improved impact resistance. Has medium machinahilitv ,and lowdecarhurization resistance Forging.
Start forging at 10-M) to I I SO “C I I905 to 2 100 “F) Do not forge after temperature of forging stock drops helow Vi “C (I695 “F)
Recommended Normalizing. Annealing.
Heat Treating
Practice
Do not nomralire
Heat to 870 to 9OO’C ( 1600 to IhSO “FJ. Lise Iouer limit for small sections and upper limit for I,aqe sections. Pack annealing in tightI> closed containers or using a controlled atmosphere or vacuum is required to minimize decarhurization. The packing material can he dq sand or lime to which a small amount ofcharcoal has heen added. Burned cast iron chips are also satisfactory. Llse a container that is onl! slightly larger than the load to minimize the amount of puchinp material required. This allo~vs the pack to heat rapidly. After the steel has reached the annealing temperature. it should he held at temperature for I h per inch of thickness of the container. Cool slot\ Iy in furnace IO 6%) ‘C ( I XI0 “Ft at a rate not to tweed 22 “C t-t0 “F) per h. after \i hich a faster coolmg rate will not affect final hardness. Typical annealed hardne\s. 235 to 269 HB
Stabilizing. Optional. For intricate shapes, stress relieve temper at IS0 to 1611‘C (300 to 320 “F) briefly. Refrigerate at -100 to -195 “C (-150 to -320 “FJ. Temper immediately after part reaches room temperature Tempering.
Temper at S-10 to 595 “C ( 1000 to I IO5 “F) for at least 1 h. cool to room temperature. and retemper for 2 h. Approximate tempered hardness as tt corresponds to tempering temperature. 65 to 60 HRC
Recommended l l l l l l l l l
Roqh machine Stress relieve (optional Finish machine Preheat Austenitizc Quench Stahilizr (optional t Temper/douhls Final gnnd to size
Processing t
Sequence
Tool Steels / 661
M41 Chemical
Composition. AISI: Nominal. I. IO C. 4.35 Cr. 3.75 hlo. 2.00 V. 6.75 W. 5.00 Co. AISI/UNS: Composition: I .OS to I. IS C. 0.20 to 0.60 hln. 0.1s to 0.50 Si. 0.30 Ni ma\. 3.75 to 4.50 Cr. 3.25 to -1.25 klo. I.75 to 2.25 V. 6.25 IO 7.00 W. 7.75 IO X.75 Co Similar Steels (U.S. and/or Foreign). ASTM A600 (M-&l I: FED QQ-T-So0 thl--I I J: I Ger.) DIN I .32-l5. I X46: (Fr. I AFNOR .A3S-590 -137-t Z I IO H’KCDV 07-OS-OS-04 tJap.j JIS G-t-403 SKH 55: tS\rcd., SS ‘736
Characteristics.
The high carbon and cobalt content of this grade impart super high-speed properties. Hardness as high as 70 HRC is obtainable. Along with other high-speed cobalt grades. it ranks highest in resistance to softenin! at elevated temperatures. Has a low toughness rating among tool steels m general. as do other high-speed steels. However. using a levier austenitirinp temperature results in lower hardness and improved impact resistance. Has medium machinability and low decarburization resistance
662 / Heat Treaters
Guide
Forging. Start forging at IWO to I IS0 “C ( 1905 to 2 100 “F). Do not forge after temperature of forging stock drops below 925 “C ( 1695 “F)
Recommended Normalizing.
Heat Treating
Practice
Do not normalize
Annealing. Heat to 870 to 900 “C i I600 to 1650 “FL Use lower limit for small sections and upper limit for large sections. Pack annealing in tightly closed containers or using a controlled atmosphere or vacuum is required to minimize decarburization. The packing material can be dry sand or lime to which a small amount ofcharcoal has heen added. Burned cast iron chips are also satisfactory. Use a container that is only slightly larger than the load to minimize the amount of packing material required. This allows the pack to heat rapidly. After the steel has reached the annealing temperature. it should be held at temperature for I h per inch of thickness of the container. Cool slowly in furnace to 650 “C ( I200 “F) at a rate not to exceed 23 “C (40 “F) per h. after which a faster cooling rate will not affect final hardness. Typical annealed hardness. 235 to 269 HB
II90 to 1215 “C (2175 to 2220 “Fj for 2 to 5 min. Use 1-t “C (25 OF) lower when hardening from salt. Use shorter time for small sections and longer time for large sections. Tools austenitized at the lower end of the temperature range will have greater toughness. u hen compared to tools austenitized at the upper end of the range where greater alloy solution serves to impart higher hardness and hot hardness. Quench in oil. air. or salt. As-quenched hardness. 63 to 65 HRC
Stabilizing. Optional. For intricate shapes. stress relieve temper at I50 to 160 “C (300 to 320 “F) briefly. Refrigerate at -100 to -195 “C (-150 to -320 “FL Temper immediately after part reaches room temperature Tempering. Temper at S-IO to 595 “C ( IO00 IO I I05 “F) for at least 2 h. cool to room temperature. and retemper for 2 h. A third temper is recommended. Approximate tempered hardness as it corresponds to tempering temperature. 70 to 65 HRC
Recommended l
SttX?SS Relieving. Optional. Heat to 650 to 675 “C (I200 to I245 “F) and hold for I h per inch of cross section (minimum of I h). Cool in air
l
Hardening.
l
Preheat at 730 to 845 “C ( I350 to IS55 W. Double preheating in one furnace at 540 to 650 “C ( 1000 to I200 “F) and in another at 845 to 870 “C (IS55 to 1600 “Fj will minimize themral shock. Preheating time. after all sections of the tool have reached equal temperature. should he twice the length of time required at the austenitizing temperature. Heat rapidly from the preheating to the austenitizing temperature. Austenitize at
l
l l l l l
Processing
Rough machine Stress relieve (optional) Finish machine Preheat Austenitize Quench Stahilize toptional) Temper/triple Final grind to size
Sequence
662 / Heat Treaters
Guide
M42 Chemical
Composition. AISI: Nominal. I, IO C. 3.75 Cr. 9.50 MO. I. IS V. I.50 W. 8.00 Co. AISI/UNS: Composition: I .OS to I. IS C, 0. IS to 0.40 Mn. 0. I.5 to 0.65 Si. 0.30 Ni max. 3.50 to 4.25 Cr. 9.00 to 10.00 MO. 0.95 to 1.35 V, I.15 to I.85 W. 7.75 to 8.75 Co Similar
Steels (U.S. and/or Foreign). ASTM A600 (M-42): FED QQ-T-S90 (hl-42); (Ger.) DfN I .X37: (Fr.) AFNOR A35-590 A-175 I IO DKCWV 09-08-04-02-01: iJap.) JIS G-t403 SKH 59; (U.K.) B.S. 1659 BM12 Characteristics.
The high carbon and cobalt content of this grade impart super high-speed properties. Hardness as high as 70 HRC is obtainable. Especially suitable for demanding cutting. such as heavy chip rcmoval of super alloys. Along with other cobalt high-speed grades. it ranks highest in resistance to softening at elevated temperatures. The principal alloying element is molybdenum. making it an economical grade for the high-speed properties it provides. Has a low toughness rating among tool steels in general. as do other high-speed steels. However. using a lower austenitizing temperature results in lower hardness and improved impact resistance. Has medium machinability and low decarhurization resisuance
Forging. Start forging at 1040 to II50 “C (1905 to 2100 “FL Do not forge after temperature of forging stock drops helow 925 “C ( 1695 “F)
Recommended Normalizing.
Heat Treating Practice
Do not normalize
Annealing. Heat to 870 to 900 “C t 1600 to 1650°F). Use lower limit for small sections and upper limit for large sections. Pack annealing in tightly closed containers or using a controlled atmosphere or vacuum is required to minimize decarburization. The packing material can he dry sand or lime to which a small amount of charcoal has been added. Burned cast iron chips are aJso satisfactory. Use a container that is only slightly larger than the load
to minimize the amount of packing material required. This allows the pack to heat rapidly. After the steel has reached the annealing temperature, it should be held at temperature for I h per inch of thickness of the container. Cool slowly in furnace to 650 “C ( I200 “F) at a rate not to exceed 22 “C (10 “F) per h. after which a faster cooling rate will not affect tinal hardness. Typical annealed hardness. 235 to 269 HB
Stress Relieving. Optional. Heat to 650 to 675 “C (I 200 to 12-15 “F) and hold for I h per inch of cross section lminimum of I h). Cool in air Hardening. Preheat at 7.10 to 8-15 “C I 1350 to IS55 “F). Double preheating in one furnace at S-10 to 650 ‘C I IO00 to 1200 “F) and in another at 835 to 870 “C (I555 to I600 “l3 will minimize thermal shock. Preheating time, after all sections of the tool have reached equal temperature. should he twice the length of time required at the austenitizing temperature. Heat rapidly from the preheating to the austenitizing temperature. Austenitize at ll6Stoll90”Ct2l2Sto2l7S”F)for1toSnin.lJseI1”C(2S”F)lower when hardening from sah. This grade is available in two silicon contents, 0.30 and 0.559. H’hen 0.55% silicon is used. the maximum suggested hardening temperature is I I75 ‘“C (2 I50 “F) rather than I I90 “C (2 I75 “F), which is the usual listed maximum temperature for this grade. This reduction. when added to the I3 “C (25 “F) nomrally employed with salt-bath hardening. establishes I I65 “C (2125 “F) as the maximum in salt. LJse shorter time for small sections and longer time for large sections. Tools austenitized at the lower end of the temperature range will have greater toughness. when compared to tools austenitized at the upper end of the range where greater alloy solution serves to impart higher hardness and hot hardness. Quench in oil. air. or salt. As-quenched hardness, 63 to 65 HRC Stabilizing.
Optional. For intricate shapes. stress relieve temper at IS0 to 160 ‘“C (300 to 320 “F) hrietly. Refrigerate at -100 to -195 “C (-150 to -320 ‘F). Temper immediately after part reaches room temperature
Tool Steels / 663
Tempering.
Temper at 5 IO to 595 “C (950 to I IO5 “F) for at least 2 h. cool to room temperature. and retemper for 2 h. A third temper is recommended. Approximate tempered hardness as it corresponds to tempering temperature. 70 to 65 HRC
l l l l l
Recommended l l
Processing
Rough machine Sue& relieve toptional)
Sequence
l l
Finish machine Preheat Austenitize Quench Stahilize (optional) Temper/triple Final grind to size
M42: Hardness vs Tempering Temperature. Austenitized 1200 “C (2190 “F) and 1100 “C (2010 “F) and triple tempered
at (2 h
plus 2 h plus 2 h). Source: Stora Steels and Climax Molybdenum
M42: Microstructures.
(a) 6% nital, 750x. Austenitized at 1180 “C (2155 “F). oil quenched, triple tempered (2 h each) at 525 “C (975 “F). Spheroidal and angular carbide particles in matrix of tempered martensite. (b) 2% nital, 1000x. Austenitized at 1190 “C (2175 “F), salt quenched, air cooled, triple tempered (2 h each) at 540 “C (1000 “F). Alloy carbide particles in matrix of tempered martensite. (c) 2% nital, 1000x. Austenitized at 1225 “C (2240 “F), salt quenched, air cooled. triple tempered (2 h each) at 540 “C (1000 “F). Alloy carbide in matrix of marlensite coarsened by overheating. (d) 6% nital, 500x. A disk 12 mm (l/2 in.) thick by 76 mm (3 in.) diam, as cast. Mixture of coarse mattensite grains outlined by some spheroidal carbide particles, retained austenite. and eutectic (lamellar, near top). (e) 6% nital, 500x. Same as (d), except heated to 900 “C (1650 “F), austenitized at 1190 “C (2175 “F), salt quenched at 595 “C (1105 “F), air cooled. triple tempered (2 h each) at 550 “C (1020 “F). Tempered martensite and grain-boundary carbide
664 / Heat Treaters
M42: Isothermal
Guide
Transformation
Diagram. Austenitized
1225 “C (2240 “F). Source: Stora Steels
at
M42: Hardness vs Tempering Temperature. Quenched 1205 “C (2200 “F). Source: Teledyne VASCO
from
664 / Heat Treaters
Guide
M43 Composition. AISI: Noninnl. 1.20 C. 3.75 Cr. X.00 hlo. I. IS to I .3S C. 0.30 to I .6O V. 2.75 I+‘. 8.15 Co. AISI/UNS: Composition: 0.40 hln. O.IS to 0.65 Si. 0.30 Ni ma\. 3.50 to 1.25 Cr. 7.50 to 8.50 hlo. I.50 to I.75 v. 2.3 to 3 00 IV. 7.7s IO 8.75 co
(40 ‘FI per h. after M hish a faster cooling rate fill T! pical xuwalsd hnrdnex 2-U to 269 HB
Similar
Hardening. Preheat at 730 to X-15 “C t I MO to IS55 “F). Double preheatlnp in one furnnce at S-IO to 650 ‘C I IO00 to I200 “F) and in another at 815 to 870 .C I ISSS to 1600 “FI \\ ill minimize themlal shock. Preheating time. after all xctions of the 1001 ha\e reached equal temperature. should be t\rice the length of time requiwd at the austsnitizing temperature. Heat rapidI> from the prehrnttnp to the austznitizinp temperature. Austenitize at IISOto ll7S”Ct~I~K~to7lSO-F~f~~r~toSnin.C~se I-I”Ct2S”F)louer I\ hen hardening from wit. Use bhortsr time for small sections and longer time for large sections. Tools aujtenitized at the lo\\eer end of the temperature range I\ ill have greater toughness. u hen compared to tools austenitized 31 the upper end of the range H here greater alloy solution serves to impart higher hardness and hot hardness. Quenc.h in oil. air. or salt. As-quenched hardness. 63 to 65 HRC
Chemical
Steels (U.S. and/or Foreign).
FED QQ-T-590 thl-43): (Fr., AFNOR 09-0%O-LCP-0 I
A35590
.ASThl
A600
thl-43):
447.5 Z I IO DKW’\.
Characteristics. The high carbon and cohah content of this grade impart super high-speed properties. Hardness as high 3s 70 HRC is obtainable. Especially suitable for demanding cutting, such as heavy chip rcmob al of super alloys. Along with other cobalt high-speed grades. it ranks highest in resistance to softening at ele\ ntsd temperatures. L’s9 high ~\sar rekistance. The principal alloying element is mol~hdsnum. making it an economical gade for the high-speed properties-it protides. Has a loi\ toughness rating among tool steels in general. as do other high-speed steels. However. using a lower austsnitiring temperature results in lower hardness and improved impact resistnnse. Has medium machinability and lo\\ decwhuriration resistance Forging.
Start forging ;II IO-IO to II50 ‘C 11905 to 2100 “FJ. Do not forge after temperature of forging stock drops below 925 ‘C ( I695 “F)
Recommended Normalizing. Annealing.
Heat Treating
Practice
Do not normalize
Heat IO X70 to 900 “C I I600 to 1650 “FL llw lower limit for small sections and upper limit for large sections Path annealing in tightI) closed containers or using a controllsd atmosphere or \xuum is required to minimize decarhurization. The parking material cm be dr! sand or lime to which a small amount ofcharcoal has heen added. Burned cast iron chips are also satisfactor). Use a container that is only slightI) larger than the load to minimize the amount of packing material required. This ;1IIou.s the pack IO heat rapidI>. After the steel has reached the annealing temperature. it should be held at temperature for I h per inch of thickness of the container. Cool slou I) in furnace to 650 “C t I100 “FI at a rate not to exceed 22 ‘C
not affect linal hardness.
Stress Relieving. Optional. Heat to 650 IO 675 “C t I200 tu 1215 “F) and hold for I h per inch of cross section (minimum of I h). Cool in air
Stabilizing. Optional. For intricate bhapes. stress relieve temper at IS0 to I60 “C r3OO to 3% “F) briefl!. Refrigerate at -100 IO -195 “C t-150 to -3’0 olier part reaches room temperature _- “FL Temper immediateI\ Tempering.
Temper at S IO to S9S ‘C t9SO to II05 “F) for at least 2 h. cool to room temperature. and rstempsr for 7 h. A thud temper is recommended. Appro~m~ate tempered h.ardnea as it corresponds to tempering temperature. 70 to 65 HRC
Recommended l l l l l l l l l
Processing
Rough machme Stress relis\ e (optional) Finish machine Preheat r\uanitize Quench Slahilize (optional I Temper/triple Final grind to size
Sequence
Tool Steels
M43: Hardness vs Tempering Temperature. Austenitized at 1165 “C (2125 “F) and triple tempered (2 h plus 2 h, plus 2 h). Austenitized at 1165 “C (2125 “F) and double tempered (2 h plus 2 h). Source: Climax Molybdenum
/ 665
M43: Hardness vs Tempering Temperature. Tempering curves for M43 austenitized at 1180 “C (2155 “F) and triple tempered (2 h plus 2 h, plus 2 h) and double tempered (2 h plus 2 h). Source: Climax Molybdenum
M43: Microstructures. (a) 4?,0 nital. 1000x. Austenitized at 1190 “C (2175 OF), salt quenched at 565 “C (1050 “F), air cooled, double tempered (2 h plus 2 h) at 565 “C (1050 “F). Alloy carbide particles (white) in matrix of tempered martensite. (b) 4% nital, 1000x. Severely overheated by austenitizing at a temperature above 1205 “C (2200 “F). Tailed, fused, and angular particles of carbide in coarse martensite and retained austenite. See (a)
Tool Steels / 665
M44 Chemical COmpOSitiOn. AISI: Nominal. I.15 C. 4.25 Cr. 6.5 hlo. 2.00 C: 5.15 b’. 12.00 Co. AISl/UNS: Composition: I .I0 to I.20 C. 0.20 to 0.40 hln. 0.30 to 0.55 Si. 0.30 Ni ma\. 4.00 to 4.75 Cr. 6.00 to 7.00 hlo. I.82 to 2.7-o I’. 5.00 to 5.75 M’. I I.00 to 12.2s co Similar
Steels (U.S. and/or Foreign).
I-\STM ~600 t hl-44,; FED QQ-T-590 Iikl-44,: t&r.) DLN I .3207: (Fr.1 AFNOR AM-5904376 Z 130 KWDCV I?-07-Oh-04-03:(Jap.j JISG4103 SKH 57:tLl.K.) B.S -l6SY IUSA hi-u)
Characteristics. Has c~eme hot hardness and is suitable for highspeed cutting of supernllo>s. Qualifies us a super high-speed steel. Hardness as high as 70 HRC is attainable. Very high \ and IOH decarhurirntion resrstnnce Forging.
Start forging at IO-W to I IS0 “C t 1905 to ?I00 “FL Do not forge after temperature of forging stock drops below 935 “C ( 16% “F)
Recommended Normalizing.
Heat Treating
Practice
Do not normalize
Annealing.
Heat III X70 to 900 “C ( I600 to 1650 “F). Use lower limit for small sections and upper limit for large sections. Pack annealing in tightly closed containers or using n controlled atmosphere or vacuum is required to mininure decarhunration. The packing material can be dry sand or lime to u hich a . Use ;I container that is only slightly larger than the load to minimize the amount of packing material required. This allows the pack to heat rapidlj. After the steel has reached the annealing temperature. it should he held at temperature for I h per inch of thickness of the container. Cool slowly in furnace to 650 “C I I200 “F) at a rate not to exceed 22 “C (40 “F) per h. after u hich a faster cooling rate will not affect final hardness. Typical nnnenlcd hardness. 2-18 to 285 HB
Stress RelieVing. Optional. Heat to 650 to 67s “C (I 200 to 12-U “F) and hold for I h per inch of cross section (minimum of I h). Cool in air
666 / Heat Treaters
Guide
Hardening. Preheat at 730 IO 8-15 “C ( I350 to IS55 “FL Double preheating in one furnace at 530 to 650 “C ( 1000 to I200 “F) and in another at 8-15 to 870 “C (IS55 to 1600 “F) will minimize thermal shock. Preheating time. after all sections of the tool have reached equal temperature. should he twice the length of time required at the austenitizing temperature. Heat rapidly from the preheating to the austenitizing temperature. Austenitize at 1200 to 1225 “C (2190 to 2210 “F) for 2 to 5 min. Use I4 “C (25 “F) lower when hardening from salt. Use shorter time for small sections and longer time for large sections. Tools austenitizcd at the loser end of the temperature range will have greater toughness. when compared to tools austenitized at the upper end of the range where greater alloy solution serves to impart higher hardness and hot hardness. Quench in oil. air, or salt. As-quenched hardness. 63 to 65 HRC
Tempering.
Temper at 540 to 625 “C ( 1000 to I I60 “F) for at least 2 h. cool to room temperature. and retemper for 2 h. A third temper is recommended. Approximate tempered hardness as it corresponds to tempering temperature. 70 to 61 HRC
Recommended l l l l l l
Stabilizing.
Optional. For intricate shapes. stress relieve temper at I SO to 160 “C (300 to 320 “F) briefly. Refrigerate at -100 to -195 “C t-150 to -320 ‘F). Temper immediately after part reaches room temperature
l l l
Processing
Sequence
Rough machine Stress relieve Ioptional) Finish machine Preheat Austenitize Quench Stabilize (optional) Temper/triple Final grind to size
M44: Hardness vs Tempering Temperature. Austenitized 1220 “C (2225 “F). Source: Climax Molybdenum
at
666 / Heat Treaters
Guide
WI46 Chemical Composition. AISI: Nominal. I.25 C. 1.00 Cr. 8.25 MO. 3.20 V, 2.00 W. 8.25 Co. AlSImS: Composition: I.12 to I .30 C. 0.20 to 0.40 Mn, 0.10 to 0.65 Si, 0.30 Ni m;Lx. 3.70 to 3.20 Cr. 8.00 to 8.50 hlo. 3.00 to 3.30 v. 1.90 to 1.70 W, 7.80 to 8.8OCo Similar
Steels (U.S. and/or Foreign).
FED QQ-T-590
(MA6);
tGer.) Dm
ASTM
A600
(hl--16~:
I .3X7
Characteristics.
Has excellent hot hardness and wear resistance. Hardness to 69 HRC is attainable. Rates as a super high-speed steel. Has low toughness when rated among tool steels in general. as do other highspeed steels. Using a lower austenitizing temperature results in lower hardness and improved impact resistance. Has medium machinability and low decarburization resistance
Forging. Start forging at IO-IO to I IS0 jC (I905 to 1100 “F). Do not forge after temperature of forging stock drops below 9251 “C t I695 “F)
Recommended Normalizing.
Heat Treating
Practice
Do not normalize
Annealing. Heat to 870 to 900 “C ( 1600 to 1650 “FJ. Use lower limit for small sections and upper limit for large sections. Pack annealing in tight11 closed containers or using a controlled atmosphere or vacuum is required to minimize decarburization. The packing material can be dr) sand or lime to which a small amount ofcharcoal has been added. Burned cast iron chips are also satisfactory. Use a contamer that is only slightly larger than the load to minimize the amount of packing material required. This allows the pack to heat rapidly. After the steel has reached the annealing temperature. it should be held at temperature for I h per inch of thickness of the container. Cool slowly in furnace to 650 ‘C (IXIO “F) at a rate not to exceed 22 “C (40 “F) per h, after which a faster cooling rate will not affect final hardness. Typical annealed hardness, 235 to 269 HB
Stress Relieving. Optional. Heat to 650 to 675 “C (I 700 to I345 “F) and hold for I h per inch of cross section (minimum of I h). Cool in air Hardening. Preheat at 730 IO 845 “C t I350 to IS55 “F). Double preheating in one furnace at S-IO to 650 ‘C t 1000 to 1200 “F) and in another at 835 to 870 “C t I SSS to I600 “F) \+ ill minimize thermal shock. Preheating time. after all sections of the tool have reached equal temperature. should be twice the length of time required at the austenitizing temperature. Heat rapidly from the preheating to the austenitizmg temperature. Austenitize at II90 to 1220 “C t2 I75 to 1225 ‘FJ for 2 to 5 min. Use II “C (25 “F) lower when hardenmg from salt. Use shorter time for small sections and longer time for large sections. Tools austenitized at the lower end of the temperature range will have greater toughness. when compared to tools austenitized at the upper end of the range where greater alloy solution serves to impart higher hardness and hot hardness. Quench in oil. air. or salt. As-quenched hardness. 63 to 65 HRC Stabilizing. Optional. For intricate shapes. stress relieve temper at IS0 to 160 “C (300 to 320 “F) briefl!. Refrigerate at -100 to -195 “C (-150 to -310 “F). Temper immediateI\ after part reaches room temperature Tempering.
Temper at 525 to 565 “C (975 to 1050 “R for at least 2 h. cool to room temperature. and retsmper for 2 h. A third temper is recommended. Approximate tempered hardness. 69 to 67 HRC
Recommended l l l l l l l l l
Rough machine Stress relieve (optional Finish machine Preheat Austenitize Quench Stabilize (optional) Temper/triple Final grind to size
Processing 1
Sequence
Tool Steels / 667
M47 Chemical
Composition. AISI: Nominal. I. IO C. 3.75 Cr. 9.50 Mo. 1.25 V. 1.50 W, 5.OOCo. AISI/UNS: Composition: 1.05 to I.15 C. 0.15 to 0.40 Mn. 0.20 to 0.45 Si. 0.30 Ni max. 3.50 to 4.00 Cr. 9.25 to 10.00 MO, I.15 to 1.35 v, 1.30 to I.80 w. 1.75 to 5.25 co Similar
Steels (U.S. and/or Foreign).
ASTM
~600
(h4-47):
(Ger.) DIN I .3247
Characteristics. Similar to Ml grade with higher carbon and 5%, cobalt added. Has extreme hot hardness and is suitable for high-speed cutting of super alloys. Qualifies as a super high-speed steel. Hardness as high as 70 HRC is attainable. Very high wear resistance. Has low toughness when rated among tool steels in general. as do other high-speed steels. Using a lower austenitizing temperature results in lower hardness and improved impact resistance. Has medium machinability and low decarburization resistance
Stress RdieVing. Optional. Heat to 650 to 675 “C ( I200 to I245 “F) and hold for I h per inch of cross section (minimum of I h). Cool in air Hardening. Preheat at 730 to 835 “C (1350 to 1555 “F). Double preheating in one furnace at 540 to 650 “C ( 1000 to I200 “F) and in another at 845 to 870 “C (I555 to 1600 “F) will minimize thermal shock. Preheating time, after all sections of the tool have reached equal temperature, should be twice the length of time required at the austenitizing temperature. Heat rapidly from the preheating to the austenitizing temperature. Austenitize at I I75 to 1205 “C (2150 to 2200 “F) for 2 to 5 min. Use 14°C (25 OF) lower when hardening from salt. Use shorter time for small sections and longer time for large sections. Tools austenitized at the lower end of the temperature range will have greater toughness. when compared to tools austenitized at the upper end of the range where greater alloy solution serves to impart higher hardness and hot hardness. Quench in oil, air. or salt. As-quenched hardness. 63 to 65 HRC
Start forging at IO-IO to I I50 “C (1905 to 2100 “F). Do not forge after temperature of forging stock drops below 925 “C (I 695 “F)
Stabilizing. Optional. For intricate shapes. stress relieve temper at I50 to 160 “C (300 to 320 “F) briefly. Refrigerate at -100 to -195 “C (-150 to -320 “F). Temper immediately after part reaches room temperature
Recommended
Tempering.
Forging.
Normalizing.
Heat Treating Practice
Do not normalize
Annealing. Heat to 870 to 900 “C ( I600 to I650 “F). Use loner limit for small sections and upper limit for large sections. Pack annealing in tightly closed containers or using a controlled atmosphere or vacuum is required to minimize decarburization. The packing material can be dry sand or lime to which a small amount of charcoal has been added. Burned cast iron chips are also satisfactory. Use a container that is only slightly larger than the load to minimize the amount of packing material required. This allows the pack to heat rapidly. After the steel has reached the annealing temperature. it should be held at temperature for I h per inch of thickness of the container. Cool slowly in furnace to 650 “C (I 200 “F) at a rate not to exceed 22 “C (40 “F) per h. after which a faster cooling rate will not affect final hardness. Typical annealed hardness, 235 to 269 HB
Temper at 525 to 595 “C (975 to I I05 “F) for at least 2 h. cool to room temperature. and retemper for 2 h. A third temper is recommended. Approximate tempered hardness as it corresponds to tempering temperature, 70 to 65 HRC
Recommended l l l l l l l l l
Processing
Sequence
Rough machine Stress relieve (optional) Finish machine Preheat Austenitize Quench Stabilize (optional) Temper/triple Final grind to size
M47: Effect of Tempering on Hardness. Austenitized at 1200 “C (2190 “F) and tempered num
as indicated.
Source: Climax Molybde-
Tool Steels / 667
M48 Chemical Composition. AIsI/I!Ns (T11348): I .42 10 I .52 C, 0.15 to0.30Mn.0.15to0.40Si.0.30Ni max,3.50to4.OOCr.-1.75 to5.50Mo. 2.75 to 3.25 V, 9.50 to 10.50 W, 8.00 to 10.00 Co
to HRC 70. It is subject to decarburization in hardening, but the potential problem is avoided with proper control of furnace atmosphere. Hot rolling and rotary forging capabilities impart minimal distortion characteristics
Characteristics. Powder metallurgy steel said to be a suitable altemative for ASTM M40 alloys, particularly where high red hardness. high abrasion resistance, and good toughness are required. M38 is heat treatable
Forging. Parts are heated sloa ly and uniformly to I IO5 to I I35 “C (2025 to 2075 “F) and equalized to furnace temperature. If workpiece temperature falls below 925 “C (1695 “F). parts are reheated. After forging, parts are
666 / Heat Treaters Guide slow cooled in mica to room temperature. then subcritical11 annealed. or hot parts may be subcritically annealed after forging. Full annealing should precede hardening
Recommended
Heat Treating
Practice
Annealing.
This process take3 place atier forging and before hardemng. Parts are fully annealed b> heating uniformly to 870 “C ( 1600 “F). held at temperature 2 h. followed b) slow cooling to below 510 “C ( 1000 ‘F) at a rate not (0 exceed IS “C ~25 “Fj per h. and air cooled to room temperature. Full annealed hardness is 785 to 3 I I BHN
Hardening.
It is customto use two furnaces: one to preheat parts to 8 I5 to 845 “C ( 1500 Lo I555 “F); the second to rapidly heat from preheating temperature to the hardening temperarure of I I90 to I305 “C (2 I75 to 2200 “F) in atmosphere furnaces. or I I75 to I I95 “C (2150 to 2185 “F) in salt baths. Quenching is in oil or a salt bath maintained at S-IO to 595 ‘C t 1000 to I I05 “FL In oil quenching. an interrupted quench is recommended. particularly when parts are large in section or complicated in design. Oil quenching should continue until parts reach approximateI> S-NJto 595 “C ( 1000 to I I05 “F) (dull red color): rhsn removed from oil and sllo\red to air cool to below 66 “C (I SO “F). or until parts can be touched comfortably u irh a bare hand. In salt bath practice. parts are quenched into the bath and held long enough for them to cool to barh temperature. .At IhL point. the> are removed from the bath and allowed to cool to below 66 ‘C ( IS0 “F). Parts large in section that have been salt bath quenched grnerall~ are lourr in hardness than those processed u ith an mrerrupted quench
M48: Isothermal Transformation Diagram. Austenitizing temperature: condition: annealed. Source: Carpenter Technology Corporation
Straightening. This step should be done from the quench aI any temperature down to -125 ;C 1795 “F) Tempering.
This process should follow immediateI> after quenching and cooling parts to belou 66 ‘C ( IS0 “F). Tempennp temperature used \anes \rith the applicarlon and dewed hardness. Triple tempering is required. and four tempers are dewable. T> pical practice is SJO “C ( 1000 “F) for 2 h. follo\red by air cooling to room temperature. The cycle is repeated Iw ice to pet triple tsmpenng
M46: Effect of Hardening and Tempering Temperatures on Hardness Typical HRC values are based on austenitizing in a salt bath for 2 min at temperature, oil quenching, and triple tempering 2 plus 2 plus 2 h at indicated temperatures. Source: Carpenter Technology Corporation Hardness, HRC, at indicated TrmperinpTemperature “C
OF
.As t?urtlchtid S?S 551 566 593 62 I &Y
1163T CI2I~F-l
1191 oc (2175“F)
6361 IO00 IO3 I OS0 II00 II50 12a1
6967 69167 h8l66 67165 6316l S8/ih
1190 “C (2175 OF); critical (A,) temperature:
aRer austenitizing temperature
66/6-i 70168 70168 69167 68166 6.5162 s9t.57
835 “C (1535 “F); prior
Tool Steels / 669
M50 (Carpenter Chemical
Composition.
0.15 toO.4S hln.0.10to0.60Si.0.3(1 hlo. 0.80 to I .3 V
Similar
VM-VAR
MS1 MSO-UNS T11350: 0.78 to 0.88 C. Ni max.3.75 to-i.5OCr. 3.90 to-t.75
Steels (U.S. and/or Foreign).
1.3551: (Fr.) AFNOR
h35-590
M-50 MS)
(fier.) 480 DCV 12.16: (Seed.)
DlN I .??69. t USA h1501
Characteristics. A high-speed steel u ith excellent resistance to multiaxial stresses and softening at high service temperatures. plus good resistance to osidation. Compressive strength is high. H’hen refined using vacuum induction melting iVlhl) and vacuum arc remelting (I’,AR). the cleanliness of the product males it possible to finish parts with a high luster. Applications range from those in hearings and the missile industry to tooling GeneralI). a small amount of growth can be expected as-hardened. u hich is returned to almost zero I\ ith proper temperin!. H’ith air hardening. less size change and warpape are exhibited. but 011 hardening and salt quenching are the common practices. Parts are normall> machined in the Full? annealed condition at a maximum hardnc$s of HB 30. In thib condition. the alloj’s machinability rating ih approximateI> 65’;. of AISI 1095 or SOS that of AISI B I I I2 srzsl Decarburization. hl.iO mubt bz heat treated from a rslati\ely high temperature. and protected from changsz m surl‘ace shsmistr) dunng ths hardening operation. Treatment in neutral salt baths or in controlled atmosphere furnaces is recommended. A dew point of -9.5 to -6.5 ‘C i IS to 10 “Ft is usualI> satisfactoq Forging. Parts are preheated to 760 to 8 I5 “C ( I400 to I SO0 “F) and given time to equalize. From this point. furnace temperature is increased to IO65 to I I30 “C ( I950 to ‘050 “F 1. Forging should not he done helou 980 “C ( 1794 “F). Parts may he reheated as often as necshsaq to maintain forgmg temperature. Following fortinp. parts may he cooled in the furnace or in lime or ashes. Alier cooling. h~rgm_es should he annealed
Recommended Normalizing.
Heat Treating
Not recommended
Practice
u hen allo)
is I’lhl-L’XR
retined
Annealing.
Parts are heated unifomtij to 845 to 900 “C I 1555 to 1650 ‘FL then cooled 510~ I) in the furnace at a rate not to cvccrd IO “C (20 “F) per h. Slog cooling should he maintained until furnace is black. .At that point. furnace ma! he turned off and allo\\ed to cool naturalI>. .A maxnnum hardnrtbr of HB 235 is the result. Becuu~e ofsusceptihilit~ to decarhurlzation. part\ must he protected hy paching m buitable contamers with clean. cabt iron borinpb or b) annealing in a controlled atmosphere fumnce StreSS &!lieViIIg. Relief of mashining stresses pro\ ides for greater accursq in hardening. Procedure: rough machine: anneal helow critical at 650 to 675 “C ( IZOO to I145 “F) for minimum of I h al temperature: 4ou cool: finish machine
Hardening. The recommended processing sequence Is as follo\r 5: preheat to 8 IS “C t I SO0 “F) and equalize: then transfer parts to superheated furnace at I IO0 “C t2OlO “FL Superheat onlb long enough to allou parts to reach temperature of superheated furnace: rollou immediateI) b> qurnching to room temperature. Then cool part to approhmiatslj -75 ‘C t-105 “F) and hold for I h. Next. double temper at 5-W “C I 1000 “FL tt hich bhould produce a hardness of HRC 6’ to 64 and optimum stabilit> in ternis of size change in sen ice. An alternative general hardening recommendation: preheat to Y IS to X70 Y. ~ISOO to 1600 “F). Parts ma> he oil. an-. or high-temperature sah quenched
Tempering.
After parts should immediatrl) follow. (975 to 1020 “FL Double recommended. Parts should tempers
M50:
have ken cooled in quenching. tempering Normal tempering range is from 57-S to 550 “C tempering (2 h at heat for each temper) is be cooled hack to room temperature between
Effect of Tempering
Temperature
Austenitized at 1105 “C (2025 “F); oil quenched: (each temper, 2 h). (Source: CarpenterTechnology TemperingTemperature T
OF
double tempered Corporation) lhrdness, Rockwell C
1100 I I50
6-t/65 60162 61163 6Y6.J 61163 60161 SSlS8
I200
53m
900 950
loo0 I (J50
M50: Isothermal Transformation Diagram. Austenitizing perature: 1107 “C (2025 “F). Source: Carpenter Technology poration. A, austenite; C, carbide; F. ferrite: M, martensite
temCor-
Ultrahigh-Strength
Steels
introduction Structural steels with \ery high strength lebels are ofisn referred to as ultrahigh-strength steels. The designation ultrahigh-strength is arbitrq because no universalI) accepted strength level for the term has been established. Also. as structural steels with greater and greater strength have been developed. the strength range for which ths term is applied has gradually increased. This article describes those commercial structural steels capable of a minimum yield strength of 1380 MPa (200 ksi). In addition to the steels discussed in this article. many other proprietary and standard steels are used for essentially the same types of applications. but a~ strength Is\ els slightly belou the arhitrag, lower limit of I380 MPa (200 ksij established above for the ultrahigh-strength class of constructional steels. The ultrahigh-strength class of constructional steels is quite broad and includes several distinctly different families of steels. This article covers only medium-carbon low-alloy steels. medium-allo) air-hardening steels. and high fracture toughness steels. This chapter is made up of articles on eleven ultrahigh strength steels. Ofthese, seven are also the subjects of articles in other chapters: five as alloy steels (-1130,4140, 4340, 6150. and 8640) and two as tool steels (H-l I and H- 13). The other steels (300M, D6a and D6ac, AF I4 IO and HP-W-30) are additions to this new edition ofthe Hemr Twn/er i Gut&/or /mm atd.Sk~ls Medium-Carbon Low-Alloy Steels. The msdium-carbon low-alloy family of ultrahigh-strength steels includes AISVSAE 1130. the higherstrength -+I% and the deeper hardsnmg higher-strength -1310. Several moditications of the basic 1340 steel hale been developed. In one modification (3OOM). silicon content is increased to prevent embrittlsment I{ hen the steel is tempered at the lo\s temperatures required for \srq high
Compositions
of the Ultrahigh-Strength
Designation or trade name hledium-carbon
Steels
hln
C
strength. Ladish D-6ac contains the gram refiner vanadium: slightly higher carbon. chromium. and molybdenum than 4340; and slightly lower nickel. Other less widely used steels that ma) be included in this family are 6150 and 8tiO. Chemical compositions are given in the adjoining table. Medium-Alloy, Air-Hardening Steels. The ultrahigh-strength steels HI I modified (HI I mod) and H 13. u hich are popularly kno\rn as 5% Cr hot-work die steels. are discussed in this section. Besides being e\tensi\slg used in dies. these steels are wideI> used for structural applications. but not as uidelb as the! once were. primarily because of the development of se\cral other steels at essentially the same cost hut with suhstnntiall~ greater fracture toughness at equivalent strength. Nonetheless. HI I mod and H I3 possess some attractive features. Both can be hardened through in large sections by air cooling. The chemical romposi[ions of these steel> are given in the adjoining table. High Fracture Toughness Steels. High-strength. high fracture toughness steels as described in this article are commercial structural steels ca able of a yield strength of 1380 MPa iI ksi) and a Ktc of 100 MPa $ m (91 hsi G,. (These steels also exhibit stress corrosion cracking resistance.) .A number of developmental steels that are not full> commercial alloys are excluded from this discussion. The HP-W-30 and AFIll steels. however. are discussed belo\\. Both these alloys are of the Ni-Co-Fe type and have a numher of similar characteristics. Both are weldable. and the melt practice requires a nunimum of VAR. Control of residual elements to low levels is required for optimum toughness. The machining practices used for 3310 steel are generalI) sati.siacto~: hoaeier. Ni-Co-Fe alloys are considered more difficult to machine than are alloy steels
CompoGdun, H t %.(a) Cr Ni
Si
\’
co
low-alloy steels
-I I30
0.X-0.33
0 -m-O.60
020-O 3s
-II-IO 1340 AhlS 643-l 3Wbl
0 38-0.43 0.x-o -13 0.3 I -0-M 0.40-0.46
D-63
O.-J?-0.48
6lSO x640
0 48-0.53 0.38-0.43
0.75 I .w 0.60-0.80 0 60-0.80 0 65-0.90 0.60-0.90 0 70-o 90 0.75 I .oo
0.10-o 3s 0.20-O 35 0.10-0.35 I.-lS-I 80 O.IS-0 30 0 ‘O-O.35 0.20-0.3s
0.80-1.10 0.80-1.10 0 70.0.90 0.65-0.90 0.70.0.95 0 90-I 20 0.80-l IO 0 104X60
0.20-0.10 0.20-a.50
0 x0- I .w 0.w I .20
3.75.5.25 4.75-9.50
High fracture toughness steels AFlJlO(b) 0.13-o. I7
0. IO mu\
HP 9-4301~)
0 IO-O.35
0 lOmar 0.70 ma,
I m2.20 0.90- I. IO
Medium-alloy HI I mod
hl0
air-hardening
HI3
65&O 65-2 o(I 65-2.00 10-o 70
0.m0
70
0.05 min 0.05-0 IO 0.15.0.25
0.15:0.2s
3-l
9.50. IO so 7.0-X 0
I.20. I 41 l.lO-I 75
0 -10-0.60 0.x0- I.20
0.90. I IO 090-l 10
0.06:o. I z
~a) Pand S contents may vag with strelmakinp practice Ckuall~. these steels contain no more than 0.035 PandO O-lOS I b, .~FI410 sition. Ranges utilized
0.17-o 23
steels
0.37-0.43 0.32-0.1s
029-o
I I I 0
0 IS-0 25 0 I s-o.3 0.20-O 30 0.30-0.4~ 0.30-0.-I:‘, 0.w I IO
by some producers are narrower.
(cl HP 9430
is sprtsitied
13.50.l-I.50 -I.?-4.75
IS specified IO ho\c0.008 Pand 0.005S compoto have 0. IO ma\ P and 0. IO ma\ S Ranges utilized b> some producers are nxroaer.
700 / Heat Treaters
Guide
300M Chemical
Composition. 300hl: 0.40 IO 0.46 C. 0.65 to 0.90 hln. I.15 to 1.80 Si. 0.70 to 0.95 Cr. 1.65 to 2.00 Ni. 0.30 IO 0.45 MO. 0.05 L’ min Characteristics. Basically silicon-modified ( I .6% Si) with sliphtlj higher carbon and molybdenum, plus vanadium. Has deep hardenabilit!. along with ductility and toughness at tensile strength of I860 to 2070 hlPa (270 to 300 ksi). hlany properties are similar to those of 13-10. Exceptions due IO higher silicon content include deeper hardsnnbilit>. g-enter solid-solution strengthening, and better resistance to softening at elevated temperatures. Also. greater relief ofquenching stresses is due to ;I higher tempering temperature. However. because of high silicon and molybdenum content. 3OOM is particularly prone to decarburizntion; and when the alloy is heat treated to strength levels above 1380 hlPa (200 ksi). it is susceptible to hydrogen embrittlement. When 3OOhl is properly baked after plating. properties are better than those of 1340 or D-6x of equal strength Forging. Forging is at 1065 IO IO% “C ( 1950 to ZOOS “FL and should not be continued below 935 “C ( 1695 “FL Slou cooling in a furnnce after forging is preferred. Cooling in air in a dry place is pemlisGble
Recommended Normalizing.
Heat Treating
Practice
Heat to 9 IS to 940 ‘C ( I680 to I73 “F): holding time is based on section thickness: air cool. If parts are normalized to improve machinability, charge them into a tempering furnace at 650 to 675 “C I 13-00 to I US “F) before parts reach room tcmpernture.
In aerospace practice.
normalize
at 93
“C ( 1695 “F)
Spheroidizing-Annealing.
For either process. heat to 775 “C (I-125 ‘F) and hold for time dictated bq section thickness or furnace load: cool to 180 “‘C (895 “F) at a rate not to exceed IO ‘C (20 ‘F) per h: air cool to room temperature. In aerospace practice.
anneal at 845 “C ( IS55 “F)
Hardening. Austrnitize at 860 to 8X5 CC (I580 to I625 “F). Oil quench to belo\\ 70 “C (I60 “FL orquench in salt at 100 to 210 “C (390101lO”F). hold IO min. then air cool to 70 “C ( I60 “F) or beIoN. In aerospace practice. part?; are austenitized at 870 “C (I600 “F). Quenching is in oil or polymer. Parts iUe in the normalized or in the normalized and tempered condition prior to initial austenitizing with one exceptlon: parts normalized but not tempered shall be preheated prior to auslenitizing
Tempering.
Hold 2 to 4 h at 260 to 3 IS YY (SO0 to 600 “FL Double tempering is recommended. Tempering outside this range of temperatures con cause severe deterioration of properties. In aerospace practice. parts are tempered to a tensile strength range of I865 to 2000 hlPa i270 to 290 ksii at temperatures in the range of 30 to 3 I5 “C (555 to 600 “F) and at 300 “C (570 “F) for tensile strengths in the range of 1930 IO 2 IOS hlPa 1280 to 305 ksi). At least two tempering operations are required
Ultrahigh-Strength
300M:
Typical
Mechanical
Steels / 701
Properties
Round bars, 25 mm (1 in.) in diameter, oil quenched from 860 “C (1575 “F) and tempered at various temperatures Tempering temperature
Tensile strength
“C
OF
90 ‘05 2bO
200 -NJ0 ml bOil
315 370 4’5
300M:
hlPa
ksi
2340
3-10 310
12-m
297 289 330 260
1670 I690 I620 I-180
11-m
2oso I990 I930 I790
7OO 800
I 80 240 212 1-o 235 21s
1650
Bar diameter mm in. 15
I
75 115
3 j?,,
Eardness, ERC
6.0
10.0
Il.6
7.0
27.0
21.7
13.0 16.0
56.0 55.5
8.0 9.5 9.0 8.5
32.0 34.0 32 0 23.0
24.-l 29.8 23.7 13.6
18.0 22.0 17.5 10.0
54.0 53.0 51.0 15.5
at 900 “C (1650 “F), oil quenched from 860 “C (1575 “F), and tempered
Tensile strength hlPa ksi
\‘ield slrengtb hlPa ksi
I990 1910 2120
I690 lb30 1800
289 281 30x
300M: Transverse Tensile Properties Vacuum Arc Remelted Steel Tempering temperature T OF Air melted 315 bO0 800 loo0
Tensile strength hi hiPa
Yield strength hlPa ksi
Elongation -. in50mm (2 in.), %,
Reduction In area, %
9.5 9.5 1.3
34. I 35 0 22 3
215 236 261
of Air-Melted Elongation in5Omm (2 in.), %
and
Reduction in area
xx-1 2% 2 30
I b20 I s-lo I-180
235 22.3 215
5.0 7.0 90
II I-! 7, I-
20?0
293
I7bO
255
IS85
2 30
I620 I550 I-180
235 “5 G
70 10.0 I I.0
2s 3-I 35
1960 I760 1585
Vacuum arc remelted ‘60 115 j-t0
Charpy V-•otch impact energy J ft.Ibf
Reduction in area, %.
Effects of Mass on Tensile and Impact Properties
Round bars, normalized
-125 j-10
Elongation in50mm (2 in.), %
Yield strength hrPa ksi
ml 800 1000
F%
at 315 “C (600 “F)
Charpy V-notch impact energy when tested at 21oc -46OC -73 T (70 OFI (-lOOOF) (-50 OF) J R Ibf J ft Ibf ft Ibf J 30 26 12
” ;; 9
76 I9 9
19 I4 7
300M: Average Mechanical Properties and Vacuum Arc Remelted Heats
24 I2 7
I8 9 5
of Air-Melted
Hot reduced 96 to 98% to round-cornered square billets, about 100 x 100 mm (4 x 4 in.). Specimens were normalized at 925 “C (1700 “F), oil quenched from 870 “C (1600 OF), refrigerated, and double tempered, 2 + 2 h at 315 “C (600 “F) Plane-strain Specimen direction
Tensile strength hlPa lisi
Yield strength hfPa ksi
2095 2035
30-l 295
I805 I750
262 34
44.8
302 292
1785 I760
259 255
47.8 33.6
fraChll-l?
Reduction in area, %
lougbness (KI,) hfPadm ksidi.
Air melted Lon@udinol Tnns\rne
23.b
49.3 S8.7(a) 61.4(b)
44.9 53.4(a) 55.9(b)
57.4
51.2
64.1(a)
58.3(a) 559(b)
\acuum arc remelted Longiuiinal Trms\crse
2080 NIS
61.?(b) ~a) \i R oncn~akm.
lb) \VH’oricntation
702 / Heat Treaters
Guide
D=6a, D-6ac Chemical
Composition.
D-6a: 0.12 to 0.48 C. 0.60 to 0.90 Mn, 0. I5 1.20Cr.O.-iOto0.70Ni.0.90to l.lOMo.0.05 toO.lOV
to0.30Si.0.90to
Similar
Steels (U.S. and/or
Foreign).
No foreign equivalents
Characteristics.
D-6a is air melted in electric furnace. In processing D-6ac. vacuum arc remelting follows air melting. Mechanical properties are somewhat different. Other characteristics are identical. D-6a is a low alloy steel developed for aircraft and missile structural applications. It is designed primarily for use at room temperature tensile strengths of I800 to 2000 MPa (260 to 290 ksi). A very high ratio of yield strength to tensile strength is maintained up to a tensile strength of 1930 MPa (280 ksi). combined with good ductility. Notch toughness is good. resulting in high resistance to impact loading. The alloy is deeper hardening than 4330 and does not exhihit temper embrittlement. High strength is maintained at elevated temperatures. Susceptibility of D-6a to stress corrosion cracking and corrosion fatigue in moist and aqueous environments is comparable to that of 300M steel at the same strength level
Forging. Heat (D-6a) to temperature of 1730 “C (3150 “F) max: forging should be finished above 980 “C ( 1795 “F). Finished forgings should be cooled slowly in furnace. or embedded in a suitable insulating medium such as ashes or lime
Recommended
Heat Treating
Practice
Normalizing.
Heat to 870 to 955 “C ( I600 to I750 “F): hold for time dictated by section thickness; air cool. In aerospace practice, parts are normalized at 940 “C (I725 “F). All parts are in the normalized or the normalized and tempered condition prior to initial austenitizing treatment. An exception: parts normalized but not tempered are preheated prior to austenitizing
D-6a:
Typical
Notmalized
Mechanical
Properties
at 900 “C (1650 “F), oil quenched
Tempering temperature OC OF
Annealing.
Heat to 8 I5 to 8-15 “C ( IS00 to IS55 OF) to time dictated by section thickness and furnace load. Furnace cool to 540 “C (1000 “F) at a rate not to exceed 78 “C (SO “F) per h; air cool to room temperature. In aerospace practice, parts are annealed at 835 “C (IS55 “F). then cooled to below 540 “C ( 1000 “F) at a rate not to exceed 9.5 “C (170 “F) per h Sb’t?SS Reh?Ving. Heat to an appropriate temperature in the range of SJO to 675 “C ( 1000 to 12-U “F) and hold for I to 2 h; air cool
Hardening. Austenitize at 8-15 to 900 ‘C ( IS55 to 1650 “F) for 1/2 to 2 h. Sections no thicker than 25 mm (I in.) may be air cooled. Sections thicker than 25 mm (I in.) may be oil quenched to 65 “C (I SO “F) or salt quenched to 205 “C (100 “F) and then air cooled. For optimum dimensional stability, aus-hay quench in a furnace at 535 “C (975 “F). equalize the temperature. then quench in an oil bath held at 60 “C (140 “F) or quench in 205 “C (-IO0 “F) salt and air cool. Cooling rate during quenching signiticantly affects fracture toughness. For high fracture toughness. especially in heavy sections. austenitize at 925 “C (I 69s “F). aus-bay quench to 525 “C (975 “F). equalize. and oil quench to 60 “C (I40 “F). In aerospace practice. parts are austenitized at 885 “C (I625 “F). All parts must be in the normalized or normalized and tempered condition prior to the initial austenitizing treatment. with this exception: parts normalized but not tempered must be preheated prior to austenitizing. An austenitizing temperature of 925 “C ( 1695 “F) is pemlitted for D-6ac parts when approved by the cognizant engineering authority Tempering.
Immediately after hardening. parts are held 2 to 4 h, in the range of 200 to 700 “C (390 to I290 “F) depending on the desired strength or hardness
Spheroidizing.
Heat to 730 “C (I350 “F) and hold 5 h; increase temperature to 760 “C (I-100 “F) and hold I h; furnace cool to 690 “C (I 275 “F) and hold IO h; air cool to room temperature
of Bar from 845 “C (1555 “F), and tempered
Tensile strength hlPa ksi
Yield strength iMPa ksi
at various
temperatures
Elongation in50mm (2 in.), I
150
300
2060
299
1150
211
8.5
205 31.5 425 540 6SO
400 600 800
2ooo 1630
290 267 236
1620 1700 1570
235 217 ‘28
l-IS0 1030
210 I50
l-110
204 I11
89 8.1 9.6 130
1840
1000 1200
D-6a: Room-Temperature Times at 540 “C (1000 “F)
Properties
After Various
D-6ac: Smooth
Steel normalized
at 900 “C (1650 “F), oil quenched (1555 “F), and tempered at 565 “C (1050 “F) Tie at 54OT (lOOOOF),h
Tensile strength MPa ksi
Yield strength MPa I&
0 IO IO0
1410 1410 1330
l3-ul 1330 1260
204 204 I93
970
I95 I93 183
from
845 “C
Elongation in50mm
Reduction in area,
(2 in.). k
%
14.8 14.5 13.8
50.5 52.0 51.0
19.0 25.7 300 36.8 4s.s 60 8
18.1
Room and Elevated specimens
Charpy V-notch impact energy J ft Ibf
Reduction inarea,%
heat treated
10
I5
II I2
16 16 26
12 I9
-II
30
Temperature to a tensile
I4
Fatigue Limits
strength
of 1860 MPa
(270 ksi); test speed, 186 kHz Test temperature OC OF 24 232 288
7s -150 5.50
Tensiontension(a) hlPa ksi
Tensioncompression(b) MPa ksi
I035
I50
630
100
930 930
I35 I35
.iSO 515
80 75
(a) hlean stress equal to altematine stress (R = 0). (b) Mean stress equal to zero (R = -I )
Ultrahigh-Strength
D-6ac:
Tensile Properties
of Double-Tempered
D-6ac Billet
Austenitized 1 h at 900 “C (1650 “F), quenched in fused salt at 205 “C (400 “F) for 5 min, then air cooled to room temperature. 205 “C: second temper, 4 h at indicated temperature Second tempering temperature “C 480 510 540
Tensile strrogth OF
900 950 1000
DG-ac: Suggested Tempering (Aerospace Practice)(a) 1175-1240 MPa (170-180 ksi) 650 “C(h)
(L-1
Elongation in5Omm
Yield strength
hlPa
hi
hlPa
bi
(2 in.). $6
1686.5 1652.7 1613 4
244.6 239.7 231.0
1540.3 1519.7 1483.8
223.1 ‘20.4 115.1
11.1 I32 13.7
Temperatures
Tensile strength 1240-1380 hlPa MO-200 ksi
Steels / 703
1380-1520 MPa 200-220 bi (d)
tlX0”F) tab Quench in oil or polymer. (hi At least two tempering operaions required IC) 1st tcmper;595”C(IIOO”F)min:2ndtemper:6OOto650”CtI IlSto INO”FI.(~) Isttcmper565 “CI 1050”F~nin: 2nd temper:590 to61O”C( 1095 to Il15”F). Sourw 4MS 275911
Tempered 1 h at
Reduction iO8lW.% 40.0 44.1 47.2
710 / Heat Treaters
Hll Chemical
Guide
Modified Composition.
Hll Mod: 0.37 to 0.13 C. 0.20 to 0.40 Mn.
0.8 to 1.00 Si. 4.75 to 5.25 Cr. 1.20 to I .-IO MO. 0.40 to 0.60 V
Characteristics. This is a modification of the martensitic. hot-work die steel. AISI HI I. The significant ditference between the two is that HI I Modified has a slightly higher carbon content. The alloy can be heat treated to strengths above 2070 MPa (300 ksi). It is air hardened. resulting in minimal residual stress after hardening. HI I mod is a secondary hardening steel. Optimum properties are developed when it is tempered at temperaNres above 510 “C (950 “F). High tempering temperatures also provide substantial stress relief and stabilization of properties. meaning that the alloy can be used at elevated temperatures. Another benefit is that heat treated parts can be warm worked at temperatures as high as 55 “C ( IO0 “F) below the prior tempering temperature. or be preheated for welding. At high strength levels [those exceeding 1800 MPa (260 ksi)]. HI I mod has good ductility, impact strength. notch toughness, and fatigue life, as well as high creep and rupture strength at temperatures up to approximately 650 “C (I200 “F). The alloy is selected for parts requiring maximum levels of strength. ductility, toughness, fatigue resistance. and thermal stability at temperatures between -75 to 540 “C (-100 to 1000 “F). At elevated temperatures. parts should be protected from corrosion (oxidation) by surface treatment. The alloy has good formability in the annealed condition and is readily welded. It is subject to h>irogen embrittlement. and fracrure toughness is rather low. If used in cnttcal applications, at yield strength levels above 1380 MPa (200 ksi). car2 should be taken to eliminate small discontinuities. Parts for elevated temperaNre service are commonly nickel-cadmium plated. Such parts should be baked to avoid hydrogen induced. delayed cracking. Part surfaces may be protected from oxidation by hot dipping in aluminum or by applying heat-resistant paint Forging. The alloy is readily forged at temperacures ranging from I I20 to I I50 “C (2050 to 2 100 “F). Preferably. stock should be preheated at 790 to 8 I5 “C (I455 to I500 “F). then heated uniformly to the forging temperaNre. Forging should not be continued below 925 “C ( I695 “F). Stock may be reheated as often an necessary. Because the alloy is air hardening, it must be cooled slowly after forging to prevent stress cracks. After forging. parts should be charged into a furnace at approximately 790 “C ( I455 “F); soaked until the temperature is uniform; then slowly cooled, either while retained in the furnace or buried in an insulating medium such as lime. mica. or a siliceous tiller material such as silocel. When forgings are cooled. they should be annealed
Recommended
Heat Treating Practice
Normalizing.
Generally not necessary. For effective homogenization. heat to approximately IO65 “C ( I950 “F); soak I h for each 25 mm ( I in.) of thickness: air cool. Anneal immediately after part reaches room temperature. There is a possibility that HI I mod may crack during this treamrent
Annealing.
Heat to 845 to 885 “C ( 1555 to I625 “F) and hold to equalize temperature: cool very slowly in furnace to approximately 180 “C (895 “F). then more rapidly to room temperaNre. Treatment should produce fully spheroidized nucrostructure free of grain boundary carbide networks Stress RelieVing. Heat to 650 to 675 “C (1200 to 1245 “F): cool slowly to room temperaNre. Treatment is often used to get greater dimenstonnl accuracy in heat treated parts by stress relieving rough machined parts. which is followed by finish machining, and finally, heat treating to the desired hardness
Hardening. Preheat at 760 to 815 “C i 1400 to IS00 “F). then raise temperature to 995 to 1025 “C ( 1825 to 1875 “F) and hold 20 mm plus 5 min for each 25 mm ( I in.) of thickness; air cool. In some applications. parts may be oil quenched from low end of the hardening temperature. Air cooling, which produces less distortion than oil quenching, is more commonly used Tempering.
Heat at the secondary hardening temperature of approximately 5 IO “C (950 “F) for maximum hardness and strength, or above the secondary hardening peak to temper back to a lower hardness or strength. A minimum of I h at temperarure should be allowed, but preferably, parts should be double tempered: Hold 2 h at temperature. cool to room temperaNre. then hold 2 h more at temperature. Triple tempering is more desirable. especially for critical parts. For high temperature applications, parts should be tempered at a temperature above the maximum service temperature to guard against unwanted changes in properties during service
Nitriding. Finished machined and heat treated parts should be gas or liquid nitrided at temperatures of approximately 525 “C (975 OF). Depth of the nitrided case depends on time at temperature. For example. gas nitriding in 20 to 30% dissociated ammonia for 8 to 48 h normally produces a case depth of approximately 0.2 to 0.35 mm (0.008 to 0.014 in.) Baking. After plating in an acid bath. or after other processing that might introduce hydrogen into the metal. parts should be baked 24 h or longer at 190 “C (375 “F) or above
Ultrahigh-Strength
Steels / 711
Hll mod: Variations in Hardness with Tempering Temperatures. Specimens were cooled from 1010 “C (1850 “F) and double tempered 2 + 2 h at temperature.
Hll
mod:
Longitudinal ture
Typical
Short-Time
Elevated-Temperature
Properties
specimens taken from bar stock air cooled from 1010 “C (1850 “F) and double tempered,
Test temperature OF
oc
Tempered at .!A0 OC (1000 “F) ‘60 500 315 600 4’S -I80 510 hS0
800 900 1000 1200
Tensile strength MPa ksi
I’ield strength hWa ksi
IS20 I-190 I-l-40
I XhO
270
I8-m I670 IS80 I180 bl0
‘67 2-l’
IYIO I 700 I610 I600 I SO0 I420 12-10
AQ, as quenched
Elongation in50mm (2 in.). 3
2 + 2 h at indicated tempering tempera-
33.2
220 216 209 I98 I82 X-l.5
9.9 10.3 12.0 I’ 13.7 ‘4.8
31.5 42.6 46. I 18.2
Y.8 IO. I 10.2 10.3 I I.4 I2 2 I’ 2 15.8 19.0
3s.1 36. I 35.8 36.0 3X.8 39 3 -II 3 46.8 66.8
IO.0 IO.0 17-l 13.5 IS..5
45.0 -18. ! 52.2 56 0 62 0
729
136s
2lS X8
IZSS 583
262 246 233 23 I .S ‘I7 ‘06 I80 l-11 US
I180 I36S I310 1330 I270 II10 970 440
2lS I98 I95 I93 I84 166 I-II IO5 61
I95 190 I78 16-l I42
II30 I IO0 1010 900 790
I64 160 I46 131 IIS
Charpy V-notch impact energy J ft Ibf
Reduction in area. “0
95.2
Tempered at 565 ‘XI (1050 OF) Room I50 260 315 -Ps -180 S-LO S9S 650
Room 300 SW 600 800 900 1000 1100 I200
Temperedat595°C
(IIOO’F)
260 315 -125 a0 S-10
500 600 800 900 1000
Hll
mod:
Typical
980 590
I 340 1310 17.70 I IKI 980
Stress-Rupture
720
29.-l 11.2 42.7 40.0 39.7 ll.4 -IS.0 80.0
21.7 30.1 3 I .s 29.5 29.3 30.5 33.2 59.0
44
33
II
30
Properties
Air cooled from 1010 “C (1850 “F); double tempered
Exposure temperature OF “C Sl01a, 510(b)
9SOW IOOOtbj
SUl(S,
IOOO~C,
Elongation in50mm
Exposure time, h
Tensile strength ksi hlPa
hlPa
ksi
(2 In.), 5%
lo0 IO I00 IO 100
1790 1650 I-IS0 I385 1300
1760 1110 I300 II90 1100
255 20-l I85 I73 I60
I I.5 12.4 13.7 14.1 IS.2
260 239 210 201 I89
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
field strength
Reduction iIlWL?t&% 42.8 19.9 52.9 52.4 58.3
712 / Heat Treaters
Guide
Hll mod: Typical Hot Hardness. Specimens air-cooled from 1010 “C (1850 “F), and double tempered 2 + 2 h at indicated temperatures. Rockwell was converted from microhardness values
714 / Heat Treaters
Guide
AFl410 Chemical Composition. AFMO: 0.13 10 0.17 C. 0. IO bin max. 0.10 Si max. 1.80 to 2.20 Cr. 9.50 to IO.50 Ni. 0.90 to I. IO MO. 13.50 to l-1.50 co Characteristics. This alloy has significant resistance to stress corrosion cracking. Ultimate tensile strength-is t>picallyl&SO h,lPa (235 ksi). .At this level. a Kt, value of IS4 MPa \Im ( I40 ksi din. ) is maintained. The combination of strength and toughness exceeds that of other commercial steels. and the alloy. which is used in aircraft structural components. has been considered as an alternative to titanium in certain aircraft parts. The alloy is air hardenable tn sections up to 75 mm (3 in.) thick. Current preferred melting practice is vacuum induction melting. follo\\ed b> \acuum arc remelting. Weldabilit) is good with the gas tungsten arc (GTAU’, process. provided high purity wire is used and oxygen contamination is avoided. The microstructure of this allo) consists of Fe-Ni lath martensite. Quenching from the austenitizing temperature produces a highly dislocated lath martensite that has high toughness. as measured b> Charpg V-notch impact testing. Aging produces a cornpIe\ senes of changes in carbide structure. At approximatelj 325 ‘C (795 “F,, Fe?C is precipitated. At -155 “C (850 “F) Fe-Cr-Mo hl2C carbide is obtained. which at 480 ‘C (895 “F) u ill produce a pure Mo-Cr hl?C carbide. B) raising the temperature to 5 IO “C (950 “F). the M$Z will begin to be replaced bq \I&. which has little strengthening effect. The steel is normally austenitized and aged. The seconm hardening. due to aging, produces a maximum tensile strength uhen aged at 480 “C (895 OF). hith an aping time of 5 h. U’hen aging in the range betbeen 175 to S-IO “C (795 to IO00 “F). maximum impact energ) is obtained at SO8 “C (947 “F). At aging temperatures ahove S-IO ‘C ( 1000 “F) impact energ) drops rather sharply. The best combination of strength and ductility is obtained by aging at 5 IO “C (950 “F) Forging. reduction properties
The allo) is forgeable at I I20 “C t20SO “F). but at least 405 must be obtained below 900 “C ( 1650 “F, to ohtain masimum
Recommended Normalizing. machinability.
Heat Treating
Practice
The alloy is normally supplied in this condition for best Heat between 880 to 900 “C ( 1620 to I650 “F). hold I h for
each 25 mm t I in.) of thickness: air cool and overage at 675 “C ( 12-15 “F) for S h minimum. In aerospace practice. parts are normalized at 900 “C ( 1650 ‘0. To facilitate machining. parts (after normalizing) are heated to 675 “C (I 245 “F) for 6 h minimum. then air cooled
Annealing.
Llsuall~. normalizing and oieraging are used IO soften and stress relieve parts. A stress relief of 675 “C t 1215 “F) may be applied to relieve mechanical stress. In aerospace practice. parts arc annealed at 900 ‘C (I650 “F). To facilitate machining. parts (after normalizing) are heated to 67s “C (I 7-45 ‘FI for 6 h minimum: then au cooled
Hardening. Double ausvnitize. first at 870 to 900 jC ( I600 to I650 OF): hold I h for each 25 mm ( I in.) of thickness: oil or water quench. or air cool. depending on section size. Reaustsnitize at 800 to 815 “C (I-175 to 1500 “F): 011 or water quench. or air cool. An alternative is to single austenitize at 800 to X IS YY ( 1475 to IS00 “F). hold I h for each 25 mm ( I in.) of thickness: oil or Uater quench. or air cool. depending on section size. In aerospace practice. parts are austenitized at 850 “C (IS60 “Fj. Quench in oil or polymer. ImmediateI> after quenching. refrigerate parts at -70 “C t-90 “‘F‘, or lower. hold for I h minimum; then air warm to room temperature Tempering.
In aerospace practice. parts are tempered at 495 “C (935 “F) to obtain tensile strengths in the range of IS IS to 1655 MPa (220 to 240 ksi)
Quenching. Air cooling from the austenitizing temperature produces tensile strength. ~ouphness. and fattpus strength essentially equal to values obtained in oil or irater quenching in section sizes up to 75 mm (3 in.). Refrigeration at -73 ‘C (-100 “‘F) is optional. The aim is to reduce retained austenite. but there 15no real evidence that the treatment has any substantial effect on the material or its mechanical properties Aging.
.Age at 480 to 5 IO ‘C t89S to 9.50 “F, for 5 to 8 h. Air cooling the usual practice
is
Ultrahigh-Strength
AF1410:
Effects of Different
Heat Treatments
on Mechanical
Properties
Ultimate strength Heal treatment(a)(b) Plateof X X X X
Yield strength
MPa
ksi
hlPa
1580 1650 lb20 1660
229 239 235 ‘-II
ISIS I sso I -I90 I525
lb75
243
IS90
‘31
1585 1680 1480 1670
230 2-u 215 212
15-10 I540 1380 I510
223 223 200 223
ksi
Elongation. w
CharpY V-notch
Reduction in area, %
J
ft. Ibf
bo 69 70 73
91 83 84 II3
67 61 62 83
92
68
65 81 58 95
48 60 43 70
15 mm (-‘/a in.) thickness
+ water quench per tc J + Z + refrigeration treatment per id) + Z + \rrmiculi~e cool and refrigemoon per(e) + Z + reaustenitiwtion and refrigeration per (0 + Z
Aberage
Steels / 715
for several
16 I7 I7 I7
heats
Heat treatment percg) Plate of 75 mm (3 in.) thickness Y Y Y Y
+ \vBler quench per(c) + Z + refrigeration treatment per Id) + Z +vermiculitecwlandretigerationper(cj +reaustenitization.aircwl.andrefrigerationpertfj+Z
+Z
lb I7 I8 I7
66 70 68 69
ta)Timeat9OO”C(l650”F~or8l5”C~ISOO”F11sasfollous: I hforthel5mmt!~~~in.)plateor3hforthc75mm(3in.)plate tb)lnitialandfinalheattreatments:X=900”C(1650 “F)for I hwithaircwlingand675”C( 17SO”F)for8 hkrithaircwling; Y =9OO”C( lb50”F)for3 h~nharcoolingand675 “C( 1250”F)for8hwitha~rcwling:2=510”C(950 “F)forS h~ithaircwling.tc)81S°Ct lS(Io”F~forthetimeper(a)and~aterquenching. tdt8I~“C(lSOO”F~forthetimeper(at\s.ith~rcootingandarefrigerationaearmentof -73 “C (-100 VI. te) 815 “C (I 500 “FJ for the time per (8) with vermtculite cool and a refrigeration treatment of -73 “C (-100 “F). (f) 900 “C (I650 “F) for time per (a) with air cwling.815”C(lSOO”Ftfortimeper(a~~ith~rcoolin~,andrefrigerationat-73”Ct-100”F1.tg~900”C((650~~F)fortimeper(a~\s.ith\saterquench.815”C(1500~F)fortime perta~~ithaatrrquench.815’T((500”F~fortimeper(a~with\r.aterquench.and510”C(9~0”F~for5 h\rithlurcooling
AF1410: Effect of Aging Temperature on Impact Strength and Yield Strength. VIMNAR plate is 15 mm (0.625 in.) thick. Heat treatments: Heat at 900 “C (1650 “F) for l/2 h and water quench; heat at 815 “C (1500 “F) for l/2 h and water quench; age for 5 h at indicated temperatures and air cool. AQ, as quenched
AF1410:
Mechanical
Properties
in Various
Quenching
Media
Test specimens were 50 mm (2 in.) plate from VIM/I/AR melt with the heat treatment: 675 “C (1245 OF) for 8 h with air cooling, 900 “C (1650 “F) for 1 h, quenching, 830 “C (1525 “F) for 1 h, quenching, refrigeration at -73 “C (-100 “F) for 1 h, 510 “C (950 “F) for 5 h, and air cooling Ultimate strength Quench Atr Oil Hhkr
medium
field strength
hlPa
ksi
hlPa
ksi
1680 I750 1710
2-u 29-l 248
I -I75 15-15 IS70
21-l 221 228
Elongation, % I6 I6 lb
CharpY V-notch
Reduction in area, B
J
69 b9 70
69 65 65
ft
Ibf 51 48 48
Plane-strain fracture tougbn ess (Kk) hipa& k&K 174 IS4 160
I58 140 I46
716 / Heat Treaters
Guide
AF1410: Effect of Elevated Temperature on Room-Temperature Tensile Properties. VIM/I/AR plate 30 mm (1.25 in.) thick. Heat treatment: Heat at 900 “C (1650 “F) for l/2 h and water quench, heat at 815 “C (1500 “F) for l/i h and water quench, and then heat at 510 “C (950 “F) for 5 h and air cool
716 / Heat Treaters
Guide
HP-a-4-30 Chemical
Composition.
HP-9430: 0.29 to 0.3-l C. 0.10 to 0.35
hln. 0.20 Si max. 0.90 to I. IO Cr. 7.0 to 8.0 Ni, 0.90 to 1.10 hlo. 0.06 to 0.12 v. 1.25 to 475 co
Characteristics. This alloy is usually electric arc melted. then vacuum arc remelted. Tensile strength in the range of I.520 to I650JIPa (220 to 2-10 ksi )) and a plain-strain fracture toughness of 100 MPa \Irn (91 ksi din-1 is possible. The steel has deep hardenability and can be fully hardened to martensite in sections up to I50 mm (6 in.) thick. In the heat treated condition. it can be fomted by bending. rolling. or shear spinning. Parts are readily welded. Tungsten arc welding under inert-gas shielding is the
preferred process. Neither postheating nor postweld heat treated is required. After welding. parts may be stress relieved at approxtmately 540 “C t 1000 “F) for 2-t h. This is a stress relieving treatment and has no adverse effect on the strength or toughness of the meld metal or the base metal
Forging.
Temperatures
Recommended
should not esceed I I20 “C (2050 “F)
Heat Treating
Practice
Normalizing. Heat to 870 to 925 ‘C (1600 to 1695 “F): hold I h foreach 25 mm (I in.) of thickness t I h mint: air cool
Ultrahigh-Strength Annealing.
Heat 10 620 T
Complete martensitic transformation by refrigerating at least I h at -87 to -60 T (- I75 to -75 “F ): allow to u arm to room temperature
I I I50 “F) and hold 14 h: air cool
Strt?SS k?hfing. Usunll~ required onI> after biclding resuained sections. Heat to 540 “C ( 1000 “FL hold ? h: air cool to room ~empernture
Hardening. Austenitire at 830 to X60 “C ( I515 to I580 “F) and hold I h for each 25 mm ( I in.) of thickness (1 h min): \\ater or oil quench. HP-9-4-30:
Room-Temperature
Mechanical
Tempering. Hold al 100 to 600 “C (390 10 I I IO “F), depending on desired final su-ength: double tempering is preferred (?. h at temperature, air cooling. follo\sed b] 2 h more at temperature, ranging from 510 to 580 “C (I000 to 1075 ‘F,
Properties npical
19-53 HRC(a)
Prupertj
lh50-1790(240-‘601 I 380.I~X~I’OO-210, X-l? 2.5-35
Tensil? strength. hlPa I LA)
Yield strength. hlPa I LSII Elongation in W gage kngth.? Reduction in area. Q Chap! V-notch lnipacrenerg) .Qti. IhfrFmcture wughness I A’,,). hlPa\lm t kni.Jin. )
Steels / 717
value for hardness of U-18 HRC(b)
hlinimum
value(c)
15’0-1650,220-J-101
lS20(220)
l?lO-l38Otl9c-200)
1310(190)
12-16 35-50
‘O-27, IS-X) 66-99 thO-90)
IO 35 21(18j
X-31(18-25) 99.115t90-105,
1a,011 quenched from 8-15 ‘.C I I555 ‘FI. retiigsratrd to -73 “C I- 100 “F) and douhlr tempered a~ 2OS “~,tX!WF~. I b) Same heat treatment as (8) except double tempered at 550 “C ( IO25 “F). tc) For sections forged IO 7S mm (3 m.) or lea in thichness (or IO less than O.OI h ni-. or 2.5in:. m total cros\-vxtlonal areal. quenched to martensite and double tempered atS4O~CtIWO”F~
HP-9-4-30:
Room-Temperature
All specimens
austenitized,
Temperature of exposure
Mechanical
quenched to martensite,
T
OF
Tensile strength hlPa ksi
Not exposed m 34s -12.5 -180
-loo 650 800 900
IbSO I585 IS85 I650 I S6S
239 230 230 239 -q97
Properties
after 1000 h at Various
Elevated
Temperatures
and tempered at 540 “C (1000 ‘F)
Geld strength hlPa ksi I350 140s I 440 IWO I39S
I96 20-l 205)
203 201
Elongation iu25mm (I in.), B I-l I6 I5 I-1 IS
Reduction in area, “u 52 60 56 50 51
Charpg V-notch impact energg J ft. Ibf 39 31 38 34 26
29 30 28 2s I9
Stainless
Steels
Introduction Historically, various means of retarding or preventing corrosion of iron and steel products have been and still are extensively used. These include painting or coating with metals or sometimes nonmetals that proved helpful in inhibiting corrosion in the specific environments to which the products would be subjected. As a rule. however, coatings have limited life. They require periodic replacement to prevent corrosion. which will eventually take place. A generally more desirable approach for minimizing or preventing corrosion is by alloying. This not only provides surface protection. but also protection against corrosion throughout the cross section of the iron or steel product. A large family of heat and corrosion resisting alloys has been developed to satisfy many requirements for resistance to corrosion. heat. or both. They are kno\rn as the stainless steels.
Classification of Wrought and Cast Stainless Steels The American Iron and Steel Institute has adopted standard compositions and designation numhers for over SO grades of wrought stainless steels (Tables I to 3). These alloys are generalI> known as the standard compositions. In addition to the steels listed in Tables I to 3. there are at least 100 (perhaps many more) nonstandard compositions which are marketed under proprietary names. These nonstandard grades are produced in relatively small quantities so that AISI has not elected to list them as standard grades. In most instances. the nonstandard compositions have been developed to resist corrosion. heat. or both. in some quite specific environments. Standard Wrought Grades. AISI type numbers are in general use by producers as well as users of stainless steels. The entire family of stainless steels is divided into four major groups. The basic characteristics of each group and the AISI means of designation are summarized briefly in the paragraphs which follow. Austenitic Grades. The austenitic grades carry identibing numbers of either 200 or 300 (Table I). However, most of the steels in Table I are 300 series alloys. the chromium-nickel grades. The 200 series reprrsents a more recent addition to the austenitic series. in which some of the nickel has been replaced b) manganese. The austenitic grades are used more widely in corrosive envuonments. although some grades. most notably type 3 IO, are used for elevated temperature surface up to 650 “C ( I200 “F). Because the austenitic grades do not change their cqstal structure upon heating, they do not respond to conventlonal quench-hardening treatments. Therefore, the onI1 heat treatments that are used for these grades are: (a) full annealing by rapid cooling from elevated temperatures. th) stress relieving, and (c) surface hardening bv nitriding. Ferritic Grades. The compositions listed in Table 2 represent the Important ferritic steels and are identified as the 400 series. In corrosion resistance, these steels generally rank higher than the martensitic grades. but substantially lower than most of the austenitic grades. The fenitic grades are so named because their structure is ferritic at all temperatures. Like the austenitic grades. they cannot be hardened b> heating and quenching. Annealing to lokber hardnesses developed by cold .vorking is the only heat treatment applied to the ferritic grades, csccpt for nitriding, which is used in some instances.
Martensitic Grades. This group is so named because the steels included are capable of changing their crystal structure upon heating and cooling. They can be quench hardened to fully martensitic structures, much the same as alloy steels. The martensitic group is comprised of I2 steels, compositions of which are listed in Table 3. Steels of this group also carry the 400 series designation. Nickel is specified in only two grades. and even then, the maximum amount is 2SQ. The chromium content is generally lower than for the austenitic grades. It follows that, in general. the corrosion resistance of the martensitic grades is far lo\!er than that of the austenitic grades and. in most instances. somew hat lower than that of the ferritic grades. All of the martensitic grades ha\e extremely high hardenability to the eXtent that they can be fully hardened by quenching in still air from their austenitizinp temperatures. In addition to quench hardening. all of the martensitic grades having less than approximateI> 0.10 carbon respond to surface hardening by nitriding. The maximum hardness that can be debeloped in the martensitic steels depends on the carbon content. just as is true for conventional alloy steels. Types 403 and -I IO the conventional quench-hardening techniques used for the martensitic grades. Hardening techniques for the precipitation-hardening grades are like those used for nonferrous metals. That is. the general approach is to solution treat by heating to an elevated temperature. cooling rapidly. then age hardening hy heating to an intermediate temperature. There is. however. much difference in the techniques for the various grades.
Similarities and Differences Among the Grades The element chromium is the key to the corrosion resistance of stainless steels. One common ch‘aractsristic to all grades of stainless steels is that the) contain a minimum of I I .5 percent chromium. This IS approximately the minimum amount required for a stainless steel. which is generally conceded to be complete resistance to rusting in a noncontaminated outdoor environment. even w hen humidib approaches 1006. Grades 103 and -I IO are those grades which are the lo\\est in chromium content. but they still meet the above requirement. Another characteristic that is common to all stainless steels listed in Tables I to 5 is their high resistance to all oxidizing acids. such as nitric acid. As pre\ iousl! stated. specific requirements for corrosion or heat resistance ha\e led to the development of approximately SO grades that are considered standard, plus 100 or more nonstandard grades that have been developed for specialized applications.
720 / Heat Treaters
Table 1
Composition
me No.
201 20’ -70s 30 I 302 302 B 303 303Sr 304 3(UH 3WL 3WLN SO-IN 305
Guide
of Standard
Grades of Wrought
Austenitic
UNS No.
c
S2OlOn s20200 s2osw s30100 s 30200 S30’15 s303w s30323 s304M s30409 s30-103 S30453 s30.451 s30500 s3oxw S3OWJ sx9oa s31ollo .53100X s314x) SlhOi) S31610
0 I5 0 IS 0 I?-0.25 0. I5 0 15 0 IS 0.15 0.15 0.08 0.04-0 IO 0.03 0.03 0.m a. I2 0.08 0.20 0.0x 0.25 0.08 0.3 O.OY 0 08 0.04-O. IO 0.03
hln
P
S
0.030 0.030 0.030 0 030
Stainless
Chemical composition(a), Si Cr
316N 317 317L 32 I 32IH 329 330 317 347H 3-a
0 030 0 030 0. I50 nun 0.060 0.030 0 030 0.030 0.030 0.030 0.030 0.030 0.030 0.030 0.030 0.030 0.030 0 030 0 lOOnun 0.035 0.030 0 035 0.030 0.030 0 020 0 030 0.030 0.030 0.030 0 030 0 030 0 030
1.00 I .oo I .oo I .oo I .oo 7.00- 3 00 1.00 I .OO I .oo I 00 I .OO I 00 I 00 I 00 I .OO I .OO I .OO I .so I 90 I .W,300 I 00 I 00 I .oo I .OO I 00 I 00 I 00 I 00 I .OO I 00 I 00 0.75 I.50 I .oo I .OO I .OO
34dH
0.030
1.00
38-l
a.030
308 309 309.5 3I0 3 I OS 314 316 3lhF 3lhH 3lhL
s3;do3
316LN
Major variations from basic tjpcs are shown in Table 6. For example. types 201 and 302. are shou n as the basic types for the austenitic group. Then. the moditication and a reason for the modification are sho\
Furnaces, Temperature Controls, and Atmospheres for Heat Treating The heat treating information given in the following paragraphs applies to stainless steels in general. In a few instances. certain groups or grades demand special considerations. which will be dealt u ith separatsl) in succeeding sections. All grades of stainless steels are more sensitive to variations in heat treatment than are carbon and alloy steels. and equipment and control of the process must be maintained at a higher level of quality. no less than that used for the high-allo) tool steels. Furnaces. Direct-fired and semimuffle furnaces are not well suited for heating stainless steels. largeI) because of the lack of uniformit> of temperature. Radiant-tube heated and electric furnaces heated hj either metallic or silicon carbide resistors art satisfactory for most stainless steel
Steels %,
Ih.OO-IS.00 l?.OO-I9 (NJ I6 so- 18.00 I6 OO-18.00 17.00.19.00 I 7.00. I9 00 I7.00- I9 00 I7 [email protected] I fi.OW3O.OXJ I s.OO-1O.OO I8.00-20.00 I8.00-20.00 ISO@2000 I 7 OO- 19.00 I9.00-2 I 00 23.00-24.00 ~~.0@1100 2-I W-26.00 ?A.OIJ-26 00 23 OfI-Xi.00 I6 00.IS.00 l6.WIY Ml 1600-18.00 lh.OW 18.00 I6.00- I8 00 Ih 00-18 00 I8 00-~0.00 I Y 00-20 00 I 7 .OO- I 9 00 17.00-1900 3.00-30.00 I7.00-20.00 17.0()-19 00 17.00-1900 i7.00-1900 17f2J-19.OfJ
Ni 3.50-5.50 4.00-6.00 I 00-l 7s 6.00-8.00 8.00. IO.00 8 oo- IO.00 8.00- IO.00 R.OO- IO 00 x.00- IO 50 Y.OO- IO 50 8 oo- I ‘.OO 8.00. I1.00 Y.OO- IO.SfJ 10.50- 13.00 IOOO-I’.00 I200-IS.00 I2 00-15.00 I9 00-22.00 19.00-22.00 19.00-22 00 lO.OO- 14.00 lO.OO-I400 IO OO- I 4.00 IO OO- I-l.00 I O.OO- I-l.00 IOOO-l-1.00 I I .oo- I5 00 I I .OO- IS 00 9.00- 12.00 9.00-11.00 3.00-6.00 34.00-37.00 9.00-I 3 00 9.00- I 3 00 9 oo- 13.00 9 no- I3 00
MO
Other elemeocs 0.15 N 0.3 N 0.32-0.40 N
O.hOthr 0 ISSrmin
0. IO-O. l6N O.lO-0.16N
2.00:3 00 I .75-1.50 2 00-3.00 2.00-3 00 2.00-3.00 2.00-3.00 3.004 00 3.00-1.00
O.lO-0.16N 0.10.0.16N
SxClinun jx%CTimin 1 .oo-2 ocl
IOxCCh+Tamin BxQCmintol.OOmaxNh IOxCCb+Tamin.O.IOTa max. 02OCo mzv. 8 x QC min to I .Omax Nb. 0 IOTa
beat processing operations. The use of vacuum furnaces for this type of uorh is stsadil) increasing as the number of vacuum furnaces increases. Eutrrmely hard \ acuums are not required. In fact. they may be undesirable because of the danger of losing chromium by outgassing. The degree of vacuum that can be attained mith a mechanical pump is usually sufticient. hlolten salt baths are suitahle for some. but not all. heat treating operations invol\ing stainless steels. If the baths are kept in first clzs condition. the! are very good for heating the martrnsitic grades before quenching or air cooling. Howrier. the salt used for the heating medium at 959 to 1065 “C ( I750 to 1950 “F, is composed mostly of barium chloride, \vhich is \ eq ditKwlt to remove unless it is quenched at approximately 595 “C. t IlO5 “F) into a salt which is soluble in hot Water. This intermediate quench does not in any day interfere \\ith the hardening process. Molten salt baths nre also satisfactor) for heating the ferritic grades for annealing. because the temperatures used for this operation are accommodated by salts that can be rradil) removed. AS a rule. salt baths are not suitable for heating austenitic grades for annealing. because the temperatures involved require barium salts, ‘and very poor results are likely if the cooling process is arrested at 595 “C (I IO5 OF-,. Temperature Control. Regardless of the type of furnace used. the bc>t posbible temperature control systems should be used. and mainte-
Stainless
Table 2
Composition
of Standard
Grades of Wrought
Ferritic
UNS No. 405 WY -I?9 130 130F 43OFSr -l31 436
s4osQo S-WOO SJ?!XlO S-tSOQll
C
007
1.00
0.9-W
0 030
I II0
17.00-l9JxJ
0.2cJ
I .co I.50
0.0-W 0 0-w
0 030 0.030
I .90 I 00
I8.00-23.00 2s OtI-27 00
SU’CJO S-U600
0.N
Other elements
hl0
I.00 I .Oo I 2s I 25 I .oo I .oo
442 -I-%
0 IO-0.30AI 6 x C Ti nun. 0.75 mal
0.60(h) 0.15Senin 0.7.5-l 2s 0.75. I.25
SxCCh+Tamin. 0 70 rnxi O.SONi.O.lSAl. I?- x %Cmin-I IOTI 0 ‘5 N
unless othenr kc noted t hr hlny hc added at the nianuiacturrr’~ optron Source. .4/S/ SW/ Producrs .\ICUIM/
Composition
of Standard
Wrought
Grades of Mattensitic
UNS
Chemical
mPe
No.
C
hln
P
s
403 410 111
S-IO300 Sl IO00 s-l I-100
0.15 0 IS 0.15
100 1.00 I .oo
o.o-uJ O.O-Kl o.o-ul
-II6 4lhS.e 120 42OF -I?:!
St1600 WI673 %?ooo s1’ozo S1XlO
0.15 0.15 Over 0. I5 O\erO.lS 0.3HJ.3
0.060 0.0-W rloho
0 030 0 030 0 030 0. I SO mm o.oJbo 0.030 0 ISOmln
.nl
0.03
-131 -l-KM 44OB
s-l3100 S-MOO2
0.20
.xJ
0 60-0.75 0.75-0.95 O.%- I.20
.oo I.00 I.oCJ
lM40 0.040 ~J.041 9cJ-m
suOo3 SW
uoc
IJ~ hlaunnum. unls~j othrnvw
Composition
AlSl
0060
noted. (h1 hlay bs added at the msnuixturcr’s
of Standard
Stainless
Steels
composition(a), Si
OL Cr
0.92s
0.50 I 00 I .oo I .nrl I so I00 I .oO 0.75
II SO-I300 II so-1350 11.50-13.50 I2.W11.00 l2.00-l-l.00 I’OO-l-l.00 i2.oNl-i4.0c1 II.O@13o(J
0.930 0 030 0 030 0 osn
I .OiJ I 00 I.00 I .w
I fi.OlI- 17.00 1600-l~00 l6.col8.00 I6.00- I8.00
hlo
Ni
Other elements
1.25.2.50 0.6U h) .:
0 l5Semin
.I. O.~O-I 04)
W&b, 0 75-l 25
0. I s-0.30 v 07.5.1.2sw
I .?S-2.50 o.;s 0.7s 0 75
optron
Grades of Precipitation-Hardening
IJNS
No.
Stainless
Chemical
composition(a),
Steels
No.
C
hln
Si
Cr
%, Ni
s I7409
0.07
19
I .o
Il.0
4.i)
Sl7700 s I5700 s3sOOO s35500
9.09 9.09 0.08 0.13
I .O I .O 08 0 9s
IQ IO 0.2s 0.25
17.0 15.0 I6 5 l5.S
70 70 4s 1s
K6b’Y6
0.0x
I .-I
01
IS 0
25.(!
hlo
Other
elements
type
630 Semiaustenitic
JOCu.O.lS-045Cb+Ta
types
631 632 633 634 Austenitic
Cr !I SO-l4.SO 10.50-11 75 I-l [email protected] 16.00-18 00 I6.00- I8 00 16.00-18.00 Ih.OO-18.00 16.0@ I8 00
93035
hlartensitic
B
I .OO I .OO I .OO I.00 I .OO I.00 I .OO I .OO
139
Table 4
compositionla), Si
9.030 0.01s 0.030 O.ll?ll 0.150min 0.060 0.030 0 030
s-l3010 s-I3023 S-t3100 s-I3600
Table 3
! .oo I .oo
Steels
00-U) 0.045 oolu 0040 0.060 O.lHl 0.040 o.rMl
0.08 0.08 0. I? 0. I7 0 12 0.12 0.12 0.1’
(a) hktimum.
Chemical s
P
hln
Stainless
Steels / 721
2.2 2.75 2.75
I OAI I.?41 0.1 N 0.1 N
type
660 IBI hla
unless othrnbtse
I3
lJ.3 L’. 2 0 X.0.35
Al. O.tMI3 B
noted
nance of the control systems by e\perisnced technicians on an organized basis is mandatory. Temperatures are usually sensed by one or more correctly located thermocouples, so that true ~orkpiece temperatures are sensed. Type K thermocouples are most often used. although types R and S may also be used. The accuracy of all thermocouples should be chscbed at least ebery two creeks. sometimes more often. The themrocouplc should be discarded when its drift exceeds -3 ‘C (5 “F). Radiation sensor detectors that respond to radiation are also uwd fur sensing temperatures in furnaces used for heat treatment of stainless steels. With this type of sensor. the lenb is focused on the work. The pa! bath of
sensing temperatures by chart&w in emf tthemrocouples) or by changes in radiation depends largely on furnace design and the type of morkpteces being processed. Temperature control systems that employ proportioning control rather than on-off as a means of supply mg energy to the process are preferred for furnaces used for processing stamlsss steel. because the proportioning type of input provides better temperature control. Prepared Atmospheres. Selection of atmosphere for heating stainless steels oftrn depends on whether or not any stock will be remo\cd in linishing the heat treated \\orhpieces. \Vhen the workpieces will be
722 / Heat Treaters
Guide
Table 5
Designations
Standard
MOY casting Institute designation
C
Mn
Si
0.06 0.15 0.15 0.20-0.10 0.12 0.30 0.16-0.22 0.07 0.60-0.75 0.95. I .20 0.50 0.04 0.30 0.03 0.08 0.20 0.03 0.08 0.08 0. I 2 0.16 0.08 0.20 0.20 0.07
1.00 I.00 1.00 1.00 1.00 1.00 1.00 0.70 1.00 1.00 I.00 I.00 I so I so I .so I so I so I.50 I so I so I so I.50 I.50 I.50 I SO
I so I so I so I.50 I so I.00 1.00 I .so I.50 1.50 I Ml 2.00 2.00 2.00 2.00 I so 2.00 2.00 2.00 2.00 I so 2.00 2.00 I so
410 416 420 430 431 431 I7-4PH 44OA 44oc 446
CB-30 CB-7Cu
cc-so CD-4M Cu CE-30 CF-3 CF-8 CF-20 CF-3M CF-8M CF-8C CF-I2M CF-l6F CG-8M CH-20 CK-20 CN-731
312 304L 304 302 316L 316 347 303 317 309 310
Major Variations
ASIO,pe chromium
I .oo
From the Basic Types of Stainless
Changes
in analyses
from basic t?;pe
nickel
318 321 3-17 347Se 3-t8 384 385
Cr and Ni lower for more \rork hardening Basic type. 18% Cr t 89 Ni Si higher for more scaling resistance Pand S added for easier machining Se added to improve mashinahility C loser to avoid carbide precipitation C lower for welding application Ni higher for less work hardening Cr and Ni higher with C low for more corrosion and scabng resistance Cr and Ni still higher for more corrosion and scaling resistance Ch and Ta added to avoid carbide precipitation C lower to avoid carbide precipitation Grand Ni highest to increase scaling resistance Si higher IO increase scaling resistance MO added for more corrosion resistance C lower for welding application Mo higher for more corroston resistance and greater strength at high temperatures Ch and Ta added to a! oid carbide precipitation IT added to avoid carbide precipitation Ch and Ta added to avoid carbide precipitation Se added to improte mschinahili~ Similar to 3-17. hut low tantalum content (0.101 Ni higher than 305 for se\ ere cold heading Similar IO 384. but lower Cr and Ni
Source: Allegheny
Ludlum
301 302 3028 303 303Se 30-l 3WL 305 308 309 309cr 309s 310 31-l 316 3lhL 317
Ranges for Corrosion-Resistant
Chemical
type
CA-U)
Austenitic,
Composition
Nearest AN
CAdNM CA-15
Table 6
and Chemical
composition,
Cast Alloys
5%
Cr
Ni
11.5-l-l 11.5.l-l II S-l-1 11.5-14 14-18 18-22 15-16.5 15.5-17.7 16-18 16-18 26-30 25-27 26-30 17-21 18-21 18-21 17-21 18-21 18-21 IX-21 18-21 18-21 ‘2-26 23-27 19-22
3.5-4s I.0 I.0 I .o
MO
Other
elements
0.4. I .o 0.5 0.20-0.35
Se
0.5
2.0 1.5-2.5 3.6-4.6 0.50 0.50 3.0 4.75-6.0 8-l I 8-12 8-11 8-11 9-13 9-12 9-12 9-12 9-12 9-13 12-1s 19-22 27530.5
0.5 2.5-3.2 Cu. 0.20-0.35
Cb
. 1.75-2.25
2.75-3.25
Cu
. 2.0-3.0 2.0-3.0 8xC-I.OCb 2.0-3.0 I.5 3.0-I.o
0.20-0.35
2.0-3.0
Se
3.0.4.ocu
Steels Changes
AIS1 type Austenitic,chromium
nickel
201 202 20-l 201L
in analyses
from basic type
manganese
Cr and Ni lo\\ er for more work hardening Basic type. 18% Cr + 5% Ni + 84 Mn C lower to avoid carbide precipitntion C lower for \rclding application
hlartensitic,
straight
Ferritic. 4)s 430 -13OF -13OTl d-42 446
chromium
IX Cr adjusted for special mechanical properties Basic type. I% Cr Ni added to increase corrosion reststance and mechanical properties Pand S added foreasier machining Se added to improve machinability Wadded to improve high-temperature properties C higher for cutting purposes Pand S added for easier machining Cr higher and Ni added for better resistance and properties C higher for cutting applications C higher for cutting applicanons C still higher for ~earresistance Se udded forewer machining
403 -210 11-I 416 -216Sr -l I8Spec 470 42OF 131 +I04 UOB UK UOSe straight
chromium Al added to IX Cr to prekent hardening Basic r)pe. I79 Cr Pond S added for easier machining Tttanium stabilized Cr higher to increase scaling resistance Cr much higher for improved scaling resistance
industries
ground. the surface conditions are sometimes not critical and some oxidation. decarburization. or even carbutization can be tolerated. In addition to a vacuum amtosphere and the salt bath as a means of surface protection. several gaseous atmospheres can be used under specific
conditions. Their graphs that follow.
Exothermic usually
satisfactory
advantages
and
atmospheres for
austenitizing
limitations
are discussed
in the para-
with a gas ratio of 6.5 to 7 to I are or annealing stainless steels when
Stainless their carbon content does not exceed 0. IS%. The higher carbon grades are strongly susceptible to decarburizing in the exothermic atmospheres. The workpieces will usually be covered with a thin film of greenish oxide. which should be removed in tmishing for maximum corrosion resistance. Endothermic atmospheres have been used extensively for various stainless steels. The principal disadvantage in using these atmospheres is the danger of carburizing if the carbon potential of the atmosphere is not precisely, controlled to match the carbon content of the steel being treated. Carbunzation is literally poison to surfaces of stainless steels. VaCUUIII provides the near perfect atmosphere for heat treating stainless steels.
Steels / 723
While the thermal conductivity of stainless steels does vary to some extent among grades. this variation is seldom of any practical significance in planning the heating cycles. However. the differences m thermal conductivity between carbon or alloy steels and stainless steels must be considered in establishing the heating cycles. For stainless steels, the thermal conductivity is roughly one half that of carbon and alloy steels. For this reason, the time cycle beginning with the time the instruments shonn “at heat” should be approximately twice as long for a stainless steel workpiece as compared with a part of similar size and \reight of c‘arbon or alloy steel.
Austenitic
Stainless
Steels
Introduction The austenitic stainless steels may be di\ ided into three groups: (a) the normal unstabilized compositions, such as types 201. 202. 205. 301. 302. 303. 301. 3MN. 305. 308. 30’3. 310. 316, 316N. 329. 330. and 3X-l (of these. 201. 703. 304N. and 3 l6N are high-nitrogen grades); tb) the stabilized compositions. principalI) types 32 I. 347. and 348: and (c) the extralow-carbon grades. such as types 304L. 3 l6L. and 3 I7L.
Recommended
Heat Treating
Practice
The steels listed in the table on this page cannot he hardened except bk cold ~orhing. Only three apes of heat treatments are applicable: 13) full annealing. th, stress relies mp. and tc) nitriding. Regardless of the treatment used. loading austenitic stainless parts into the furnace requires special consideratmn hecause of their high thermal expansion. approslmately 50% greater than for carbon or allob steels Therefore. spacing bet\ieen the parts must he adequate to allow for this sspansion. Stnching. when necessq. should he employed judiciousI) to avoid deformation of the parts at elevated temperature. Annealing the Unstabilized Grades. SIWIS of the 200 series. members of the 300 series from 301 through 3 17. and types 32Y. 330, and 38-l are all unstabilized. These steels are annealed to ensure masimum corrosion resistance and to restore m;kmtml softness and ductilit!. u hich result from cold uorl\inp. During annealing. carbides. \ihich markdl~ decrease resistance to intergranular corrotion. are dissohed. Annealinp temperatures. H hich \ ar) somewhat u ith the composmon of the steel. are gl\sn in the adjoining table. Because carbide precipitntlon can occur at temperature\ between 425 and 900 “C i7YS and I640 “FI. annealing temperature should he bafel) aboLe this limit. hloreover. because all carhidss should be in solution hefore cooling begins and because the chromiuni carbide dissolves SIOU Iv. the highest practical temperature consistent with limited grain Fro\{ th js Accted. This temperature is in the \ icinit! of IO95 “C (2005 “FJ. Cooling from ths annealinp temperature must he rapid. no more than approximately 3 min in cooling from 870 to 475 “C t 1600 to 795 “F). hut it must also be consistent with limitations of distortion. IVhenever considerations of distortion permit. eater quenching is used. thus ensuring that dissohed carbides remain in solution. Because they precipitate carbides more rapidly, types 309 and 310 invariahl) requlrs uatsrquenchinp. Where practical consldcrations of distortion rule out such a rapid cooling rate. cooling In an air blast is often used. b’ith some thin-section parts. e\en this intermediate rate of cooling produces e\cessi\e distortion. and parts must he cooled in still air. If cooling in still air does not pro\ ide a rate sufficient to prevent carbide precipitation. maximum corrosion resistance will not be obtained 4 solution to this prohkm is the use of a stabilized grade. Annealing the Stabilized Grades. T)pe> 32 I. 317. and 348 contain controlled amounts of titanium or columbium plus tantalum. \i hich render the steel nearly immune to intergranular precipitation of chromium carhide and its adverse effects on corrosion resistance. Ne\erthelss\. these allo);s may require annealing to relieve stresses. increase softness and ductllit). or provide additional stabilization. To obtain masimtmi Ainess and ductility. the stabilized pades are annealed at the temperatures shown in the Table below. Unlike the unstabilized grades. these steels do not usualI> require water quenching or other acceleration of cooling from the annealing temperature to preient suhsequent interLmnnular corrosion. Air cooling is pensraIl! adequate. Ho\
Full Annealing Temperatures for Austenitic Stainless Steels Qpe
Annealing temperature
AISI
UNS
OF
T
201 ‘02 20s
s20100 S20200 s20500
301 302 3028 303 303% 304 3c4L
s30100 s3omYl S30215 S3O300 s30323 S3O-lOO s3wo.3 s30430 s304s I S30500 s 30Y00
18.50-2050 1850.2050 19so IXSO-2050 I8sO-2osO
1010-1120 1010-1 I20 I065 101@1120 1010-1120 1010-1 I20 1010-1120 1010-1120 1010-1120 1010-1120 1010-1 I20 1010-1120 1010-1 I10 1010-1 I20 1010-1120 1040-1120 1040-1150 1040-1150 II50 IOlfJ-I I20 1010-1 I20 109s 1010-1 I20 1010-1120 1040-1095 955-l I20 955-980 1065-1175 1010-1120 1010-1120 1040-l IS0
J&N 305 W3 309 30% 310 310s 31-l 316 316L 3lhF 316N 317 317L 321 33 330 347 348 38-I
s30900 S309OY S3lOOrl S31008 s.1140 S31600 S3160.3 s3 I620 S3165l s317OO S? I703 s32100 s32900 NO8330 s3-1700 s31800 S384W
I MO-2050 I8SO-2050 I850-2050 ItGO-2050 I8SO-2050 I850-2050 I850-2040 I850-20.50 IXSO-2050 I9oQ2OSO 1900-2050 1900-z IO0 1900-2100 2100 I850-2020 ISjO-2050 2ooo 1850.2090 I850-2050 1900.2000 I7SO-2050 1750. I800 1950-Z I SO IXW-2050 I MO-2050 1900-2100
When maximum corrosion resistance of t!pe 321 is required, using a correctke heat stabilizing treatment may be necessary. This treatment consists of holding at 845 to 900 “C (1555 to 1650 “F) for up to 5 h. depending on section thickness. Such a treatment may he applied before or during the course of fabrication. If needed. this treatment may be followed by a short stress relist in@ treatment a~ 705 “C t I300 “F) Lrithout danger of carbide precipitation. This treatment is seldom. if ever. used for grades 347 and 346. Annealing the Extra-Low-Carbon Grades. Types 30-1~ tsstra low carbon). 3 l6L. and 3 l7L are intermediate in precipitation of chromium carhidss to the stabilized and unstabilized grades. Carbon content to.03 maximum) is low enough IO reduce precipitation of intergranular carbides to a safe level. Thus. these steels can he held in the sensitizing range of -125 to 815 ‘C (7YS to I500 “F) for periods up to 2 h and cooled SIOU I> through this range. without danger of susceptibilit! to intergranular corrosion m natural atmospheric environments. This characteristic is of particular value In ivelding. flame cutting. and other hot working operations. These grades do not require the quenching treatment that unstabilized grades require to retain carbon in solid solution. Nevertheless. the lowcarbon alloys are not satisfactory for long service in the sensitizing temperature range. hecausc they are not completely immune to the formation of csrhides deleterious to corrosion resistance.
Austenitic Stress Relieving the Austenitic Grades. Quenching from the annealing temperature range within the usual period of 3 min is a drastic thermal treatment. This treatment may generate new stresses. particularI) if the overall cooling is not uniform or if the fabricated article is not of symmetrical contour. Excessive marpage (thermal distortion) may he cncountered. Cooling rates should be as uniform as possible. regardless of whether the fabricated article is fast coolsd in air. by ~aater sprays. or by complete immersion. Stress relieving of the quench-annealed parts may he accomplish2d bl heating them within the temperature range of 230 to 100 “C (445 to 750 “F) for relatively long periods of time. often several hours. This treatment u ill not impair corrosion resistance or mechanical properties. It can he applied to any of the austenitic grades. although it is most often used for the unstabilized grades because they are more often subjected IO drastic quenching, as described ahove. Nitriding the Austenitic Grades. Austenitic stainless steels can be nitrided by the gas process. urherein the ammonia is dissociated in a separate cracking unit prior to its entry into the workpiece zone. Only the stabilized or extra-low-carbon grades are recommended for nitriding. for the obvious reason that the nitriding vmperature of approximately 540 “C (I000 ‘F) is in the sensitizing range. Further, the nitrided case that can he achieved on the austenitic grades is very thin, seldom more than 0. I25 mm (0.005 in.). Therefore. no finish-
Stainless Steels / 725
ing opzrations can be permitted or the case will he removed. In addition. nitriding serious11 impairs resistanc2 to corrosion in most media. Thus. nitriding of austcmtic stninlzss steels is done only for highly specialized applications: for example. where the material must he nonmagnetic and still have an ahrasion-resisting surfacs. Forging the Austenitic Grades. These steels are more difficult to forge than ar2 carbon or alloy steels. because austenitic stainless steels have high hot strength. However. because the) do not undergo a phase change. most of them can be forged o\er a reasonably broad temperature range aho\ 925 “C ( I695 OF). Escsptions to the above are types 309. 3 IO. and 3 II. u hich should not be forged at temperatures much above 1095 “C (2005 “F) because they are susceptible to formation of delta ferrite. \t hich impairs forgeabilitj. In forging of the austenitic grades. the finishing temp2ratures are more important. Pwferablj. finishing tempsrature should not drop below 975 “C (I695 “F) and ne\er below X70 “C t I600 “F). All hut the stabiliz2d grades 32 I. 347. and 348 and those hearing the suftis lrtter L (extra Ion carbon) should be cooled. liquid quenched if necessm. from approsimately 870 “C ( I600 “F) to a black heat in no more than 3 min. Cooling rates for the stabilized and the extra-low-carbon grades are less critical. In addition. the more highly alloyed gradrs 309. 310. and 31-l an limited in finishing temperature. because at lower temperatures the) are susceptihls to both hot tsaring and formation of sigma phase.
Austenitic
Stainless
Steels / 725
201 Chemical
Composition.
AISI/UNS (S20100):0.IS C mas.
5.50 IO
7.5 hln. 0.060 P max. 0.030 S max, I .OO Si mas, 3.50 to 5.50 Ni. lb.00 to I X.00 Cr. 0.75 N max
Similar
Steels (U.S. and/or
A3 I?. A-IX.
A666; FED QQ-S-766:
Foreign).
AShlE
SA-I I?:
.\SThl
SAE J-IO5 t 3030 I j
Characteristics.
An austemtic grade using a combination of manganese and nickel. l!sed primarily m corrosive em ironments or where bright metal appearance is required. Hardsnahls bq cold \toork onI). Heat treatnicnt limited to: annealing to restore maximum corrosion resistance. softness. and ductility after cold norking; stress relic\ ing u hen required for stresses that occur from drastic quench from annealing temperature; and, on rare occasion. nitriding to impart thin. wear-resistant surface
Forging. Start forging at I I SO to 1330°C (2 100 to 2245 ‘?). Do not forpc after forging stock drops below 95 “C ( 16% ‘>Fj. Cool to black color in less than 3 min. using liquid quench if necessq
Recommended Normalizing.
Heat Treating
Practice
Do not normalize
Annealing. Anneal at 1010 to I I20 ‘C ( 1850 to 2050 %. To guard against distortion of thin. delicate parts. leave ample room for expansion betirern parts. Stainless grades expand abou~ twice as much as carbon and low-alloy steels. Allo\\ enough time for through heating after thermocouple has reached temperature. Stainless grades have approximately half the thermal conductit it, of carbon and low-alloy steels, Choice of atmosphere depends on finish desired and \i hether surface stock \\ill be removed. For bright annealing. use vacuum or an atmosphere of hjdrogsn or dissociated ammonia at dew point of -62 to -74 “C t-80 to -100 “F). Parts must he thoroughly clean and dr!. Inert !ase\ argon and helium (although elipensive) and nitrogen. with dew pomts of less than -5-l “C t-65 v). can be used. They lack the reducing etTect of hydrogen. so slight discoloration in the form of chrome oxide can result. Salt, exothem&, or endothermic atmospheres are satisfactory for nonbright annealing. Salt is difficult to remove. and rinse quenching at 595 ‘C i I IO5 ‘%) is not recommended. hecause interrupted quench at elevated temperature cannot be tolerated. Exothermic and endothermic atmospheres must he carefully controlled at
equiialrnt carbon potential to avoid carhuriration. which &ill seriousI> lower corrosion resistance. Sams prohlsm \\ith atmosphere annealing. If osidizinp conditions are preient. scale will form. Difticult to remove in subsequent dsscaling operatlons. Cool rapidI> from annealing temperature: no more than 3 mm to black color. Section SIZS determines quenching medium: water for heavy sections. air blast for intermediate sizes. and still air for thin sections. Carbides can precipitate at ernin boundaries \\ hen parts are cooled too slowly between -125 to YOt?“C I 795 to I650 %F,. In aerospace practice. parts are annealed a~ a set temperature of 1065 “C I 1950 OF\ and quenched in water ulth one exception: parts under 2.5 mm (0. IO in. ) thick ma> be air cooled or polymer quenched to minimize distortion. See table for soahing times Note: approval of the cognizant rnginrsrinp organization IS rsqurred for annealing material in a strain-hardened condition. such as ‘,‘-I hard: for stress relieving; or for dimensional stabiliratlon. Heat treating or \IOH cooling unstabilized grades between 170 to 815 “C (875 to I SO0 ‘91 is prohibited. except for 304L and 3 l6L Stress kdit?Ving. Parts cm be relieved after quenching to achieve dimensional btabilit>. b> heating to 230 to 400 “C (4-15 to 750 ‘%) for up IO several hours. depending o11 section size and without change in metallographic structure. In aerospace practice. parts are webs relieved at 900 “C ( I650 “F). and quenched m irater. As an alternative. parts may be stress relieved at snnsaling temperatures. Sections under 2.5 mm (0. IO in.) thick ma> be air cooled to minimize distortion. Parts fabricated from steel in the strain-hardened condition. buch as I,‘> hard. shall not be stress relieved without permission of the cognizanlsrigirissrin~ authority. When stress relieving after welding. hold for 30 min nznimum at the stress relic\ inp temperature. Heat treating or slog cooling of unstabilized grades between 170 to X IS “C (875 to IS00 “FI is prohibited. scspt for 304L and 3 16L. See table for soahing times
Nitriding. No1 recommended. Case seriously impairs corrosion resistance in most media. Case seldom more than 0. I27 mm (0.005 in.) deep. Only used in specialized applications u here material must he nonmagnetic and ha\s \\rar-rcsibtunt wrface. If nitrided, parts must be in annealed condition to prevent flaking or blistering of nitrided case. Atl sharp comers
726 / Heat Treaters
Guide
should be replaced with radii of not less than l .S9 mm (0.06 in.). Film of primarily chromium oxide, that protects stainless alloys from oxidation and corrosion. must be removed prior to nitriding. Accomplished by wet blasting. pickling, chemical reduction in reducing atmosphere, submersion in molten salt. or by one of several proprietary processes. If’ doubt exists that complete and uniform depassivation has occurred, further reduction of the oxide may be accomplished in furnace hq means of reducing hydrogen atmosphere or suitable proprietary agent. After depassivation. avoid contamination of surface by finger or hand marking. Single-stage nitriding is adequate at 525 to 550 ‘C (975 to 1020 ‘%) for 20 to 48 h (depending. on case depth required). Dissociation rates for single-stage cycle are 20 to 3S%,. Hardness is as high as 1000 to 1350 HK on surface. 48-h cycle
201:
Soaking
Times (Aerospace
Diameter or thickness(a) of maximum section mm (in.) inclusive upl02.50t0.100) over3.501o6.25 CO.1001o0.250) uxr 6.25 to 12.50 (0.250 IO 0.500) wcr I2 50 to 25.00 (0.500 to 1.00) over 25.00 to 37.50 ( I .oO 10 1.50) over 37.50 to 50.00( I SO to 2.00) o~erS0.001o62.50(2 CO to 2.50) over 62.50 to 75.00 (2.50 IO 3 00) over 75.00 (3.OOJ
Practice)
Recommended l l l l l l
17 18 35 10 35 SO 5s 60 (Cl
(a) Thickness is minimum dimension ofheal iest section of part or rwsled load of parts (bJ1.2Shplus 15minforeve~ l~.Smmt0.5in.~orincrema1tofl2.Smm(O.Sin.~o~er 75mm(3in.).(c) I h.Snlinplus5minfore\ery 11.5mmt0.5in.)orincrementofl-7.S (05 in.) over75 mm (3 in ). Source: AhlS 2759/-l
Processing
Cold work Anneal and quench Remove surface contamination Stress relieve Depassivate (if nitriding) Nitride (if required)
201: Microstructure.
Minimum soaking time Atmosphere furnace Salt bath min min 20 2s 45 60 75 90 105 120 (hl
produces case extending to 0. I27 mm (0.005 in.) with approximately 800 to 1000 HK. Case will rapidly drop to 200 HK core hardness. at approximately 0. I65 mm (0.0065 in. I
Sequence
(if required)
HNO,-acetic-HCI-glycerol, 250X. Strip, annealed at 1065°C (1950 “F) for 5 min. Cooled rapidly to room temperature. Equiaxed austenite grains and annealing twins
726 / Heat Treaters
Guide
AIWUNS (S20200): 0. Is C, 0.06 P, 0.030 Chemical COInpOSitiOn. S. I .OO Si. 1.0 to 6.0 Ni. 17.00 to 19.00 Cr. 7.50 to 10.00 MO. 0.25 N
Recommended Normalizing.
Similar
Steels (U.S. and/or
Foreign).
Heat Treating
Practice
Do not nomlalize
ASTM ~314. ~412. ~-129,
A1763. A666; FED QQ-S-763. QQ-S-766 STD-66: SAE J-IO5 (30202)
Characteristics. A basic. highly available austenitic grade. Similar to in type 302. except some nickel replaced by manganese. Used primarily corrosive environments or where bright metal appearance is required. Hardenable by cold work only. Heat treating limited to: annealing to restore maximum corrosion resistance. sofmess. and ductility after cold working: stress relieving when required for stresses that occur from drastic quench from annealing temperature: and. on rare occasions. nitriding to impart thin. wear-resistant surface Forging. Start forging at I IS0 to I230 ‘C (2 100 to 2X5 OF). Do not forge after forging stock drops below 925 ‘C (1695 ?J. Cool to black color in less than 3 min. using liquid quench if necessary
Annealing.
.4nneal at 1010 to I I20 “C (I850 to 2050 ?J. To guard against distortion of thin. delicate parts. leave ample room for expansion betueen parts. Stainless grades expand about twice as much as carbon and lou-alloy steels. Allo\r enough time forthrough heating afterthermocouple has reached temperature. Stainless grades have approximately half the themral conductivity of carbon and low-alloy steels. Choice of atmosphere depends on finish desired and whether surface stock will be removed. For bright annealing, use vacuum or an atmosphere of hydro en or dissociated ammonia at dew point of -62 to -7-t ‘C (-80 to -100 4-l Parts must be thoroughly clean and dry. Inert gases argon and helium (although expensive) and nitrogen. with dew points of less than -54 ‘C (-65 ?), can be used. They lack the reducing effect of hydrogen. so slight discoloration in the form of chrome oxide can result. Salt. exothermic. or endothermic atmospheres are satisfactory for nonbtight annealing. Salt is difficult to
Austenitic
remove. and rinse quenching at 595 “C (I IO5 OF) is not recommended. because interrupted quench at elevated temperature cannot be tolerated. Exothermic and endothermic atmospheres must be carefully controlled at equivalent carbon potential to avoid carburiration. which will seriousI) lower corrosion resistance. Same problem uith atmosphere annealing. If oxidizing conditions are present. scale will form. Difficult to remove in subsequent descaling operations. Cool rapidly from annealing temperature: no more than 3 min to black color. Section size determines quenching medium: water for heavy sections. air blast for intermediate sizes. and still air for thin sections. Carbides can precipitate at grain boundaries when parts are cooled too slowly between 125 to 900 ‘C (795 to I650 ‘%). In aerospace practice, parts are annealed at a set temperature of 1065 “C ( 19.50 “F) and quenched in water with one exception: parts under 2.5 mm (0. IO in.) thick may be air cooled or polymer quenched to minimize distortion. See table for soaking times. Note: approval of the cognizant engineering organization is required for annealing material in a strain-hardened condition. such as % hard: for stress relieving; or for dimensional stabilization. Heat treating or slow cooling unstabilized grades between 470 to 8 I.5 “C (875 to IS00 OF) is prohibited, except for 3O-IL and 3 I6L Stress Rehhlg. Parts can be relieved after quenching to achieve dimensional stability, by heating to 230 to 300 “C (US to 750 ?) for up to several hours, depending on section size and without change in metallographic structure. In aerospace practice, parts are stress relieved at 900 ‘C ( I650 %1. and quenched in water. As an alternative. parts may be stress relieved at annealing temperatures. Sections under 2.5 mm (0. IO in.) thick may be air cooled to minimize distortion. Parts fabricated from steel in the strain-hardened condition. such as ‘/2 hard, shall not be stress relieved without permission of the cognizant engineering authority. When stress relieving after welding. hold for 30 min minimum at the stress relieving temperature. Heat treating or slow cooling of unslabilized grades between 470 to 815 “C (875 to 1500 %I is prohibited, except for 304L and 316L. See table for soaking times
Nitriding. Not recommended. Case seriously impairs corrosion resistance in most media. Case seldom more than 0. I27 mm (0.005 in.) deep. Only used in specialized applications where material must be nonmagnetic and have wear-resistant surface. If nittided. parts must be in annealed condition to prevent flaking or blistering of nitrided case. All sharp comers should be replaced with radii of not less than I S9 mm (0.06 in.). Film of primarily chromium oxide. that protects stainless alloys from oxidation and
Stainless
Steels / 727
corrosion, must be removed prior 10 nitriding. Accomplished by wet blasting, picbling. chemical reduction in reducing atmosphere. submersion in molten salt. or by one of several proprietary processes. If doubt exists that complete and uniform depassivation has occurred, further reduction of the oxide may be accomplished in furnace b> means of reducing hydrogen atmosphere or suitable proprietar) agent. After depassivation. avoid contamination of surface bk finger or hand marking. Single-stage nitriding adequate at 525 to 550 ok (975 to 1020 9). 20 to 48 h (depending on case depth required). Dissociation rates for single-stage cycle are 20 to 35%. Hardness is as high as 1000 to 1350 HK on surface. 48-h cycle produces case extending to 0.127 mm (0.005 in.) with approximately 800 to 1000 HK. Case will rapidly drop to 200 HK core hardness. at approximately 0. I65 mm (0.0065 in.)
Recommended
Processing
Cold work Anneal and quench Remove surface contamination Stress relieve Depassivate (if nitriding) Nitride (if required)
202:
Soaking
(if required)
Times (Aerospace
Diameler or thickness(a) of maximum section mm (in.) inclusive
ovcr2.SOro6.2S
Sequence
~0.100t00.2.50,
otsr6.25 10 12.50(0.?50to 0.500) over 12.50 to 25.00 (0.500 IO 1.00) over 3 COlo 37.50( I .OO to 1.50) ober 37.50 10 50.00 f I..50 to 2.OOJ over SO 00 to 63.50 (2.00 to -7.50~ o\er62.SOto75 COt2.50103.0OJ over 75 OOt3.00)
Practice)
Minimum Atmosphere furnace min 20 25 45 60
75 90 105 120 tbj
soaking
time Salt bath min
17 I8
35 10 45 SO 55 60 (C)
(a)Thiskness isminimumdimension ofheavieslsecrionofpartor nested loadofpans. lb)2.2ShplusIZminforeven 12.SmmtO.Sin.~orincremenrof12.Smm(O.Sin.)over 12.5 mm(O.5 75 mm(3in.J.(cJ I h. 5 mmplus 5min forcler) (0.5 in.Jover 75 mm13 in.). Source: 4hlS 27W-l
in.)orincwmentof
11.5
Austenitic
Stainless
Steels / 727
205 Chemical Composition. AISI: Nominal. 0.12 to 0.25 C max. l-t.00 to 15.50Mn.0.060Pmax.0.030S max. I.OOSi max. 1.00 to I.75 Ni. 16.50 to 18.00 Cr. 0.32 to 0.10 N. AISl/UNS (S20500): 0. I2 to 0.25 C. l-1.0 to IS.5 Mn, 0.06 P 0.03 S. 1.00 Si. I.0 to I .75 Ni, 0.32 to 0.40 N Characteristics.
Lower rate of work hardening and less change of magnetic permeability than type 202 when cold vvorked. Used for spinning and special drawing operations
Forging. Start forging at 1230 ‘C (2245 “Fj. Do not forge after forging stock drops below 925 ‘C (1695 ?3. Cool to black color in less than 3 nun. using liquid quench if necessary
Recommended Normalizing. Annealing.
Heat Treating
Practice
Do nor normalize
Anneal at 1065 ‘C ( 1950 9). To guard against distortion of thin, delicate parts, leave ample room for expansion behveen parts. Stain-
less grades expand about twice as much as carbon and low-alloy steels. Allow enough time for through heating after thermocouple has reached temperature. Stainless grades have approximately half the thermal conductivity of carbon and low-allo> steels. Choice of atmosphere depends on finish desired and whether surface stock will be removed. For bright annealing. use vacuum or an atmosphere of hydrogen or dissociated ammonia at dew point of-62 to -71 ‘C (-80 to - IO0 vi. P,arts must be thoroughly clean and dry. Inert gases argon and helium (although expensive) and nitrogen. with de, points of less than -5-l “C (-65 9). can be used. They lack the reducing effect of hydrogen. so slight discoloration in the form of chrome oxide can result. Salt. exothermic. or endothermic atmospheres are sitisfactory for nonbripht annealing. Salt is diflicult to remove, and rinse quenching at 595 “C (I IO5 %) is not recommended, because interrupted quench at elevated temperature cannot be tolerated. Exothermic and endothermic atmospheres must be carefully controlled at equivalent carbon potential to avoid carburization. which uill seriously lower corrosion resistance. Same problem with atmosphere annealing. If oxidizing condi-
728 / Heat Treaters
Guide
tions are present. scale will form. Difficult to remove in subsequent descaling operations. Cool rapidly from annealing temperature: no more than 3 nun to b1aL.k color. Section size detemnnes quenching medium: eater for heavy sections. air blast for intermediate sires. and still an for thin sections. Carbides can precipitate at grain boundaries 1shen parts are cooled too slowly betueen 13 to 900 “C i79S to 1650 TJ
Stress Relieving. Parts can be relieved after qurnchine to achieve dimensional stability by heating to 230 to -100 ‘C t-l-t5 IO 750%) for up to several hours, depending on section size and ivithout change in metallographic structure Nitriding.
Not re
molten salt. or by one of several proprietary processes. If doubt exists that complete and uniform depassilation has occurred. further reduction of the oside may be accomplished in furnace by means of reducing hydrogen atmosphere or suitable proprietary agent. *After depassivation. avoid contammation of surface by finger or hand marking. Single-stage nitriding is adequate at 53 to 5.50 “C (975 to 107-O ‘)F) for 10 to -I8 h (depending on case depth requiredt. Dissociation rates for single-stage cycle are 20 to 35cC. Hardness is as high as IO00 to 1350 HK on surface. 48-h cycle produces case extending to 0. I27 mm to.005 in.) with approximately 800 to 1000 HK. Case will rapidly drop to 200 HK core hardness. at approximately 0. I65 mm (0.0065 in.)
Recommended l l l l l l
Processing
Cold uorb .Anneal and quench Remo\e surface contammation Stress rslis\e Dspassh ate tif tutriding) Nitride (if required,
Sequence
(if required)
728 / Heat Treaters
Guide
301 Chemical
Composition. MSl/LJNS WOlOO): 0. I5 C. 2.00 nln max. 0.04S P. 0.030 S. I .OO Si maa. 6.0 to 8.0 Ni. 16.00 to 18.00 Cr Similar
Steels (U.S. and/or Foreign). AVIS 5s I 7. 5s I 8. 55 19: ASThl Al67. Al77. ASS-I. ?-\666: FED QQ-S-766: hllL SPEC hllL-S5059: SAE 1405 (30.301): rGsr.1 DIN 1.4310: (Fr.) AFNORZ I2 CN 17.0X: rltnl.~ 1lNl X I:! CrNi I7 07: (Jnp.) JIS SLIS 301 Characteristics. Llsrd under mild h\ corrosive conditions. this steel is capable of high tensile strength and duciility u ith moderate or se\rre cold ttorking. Nonmagnetic when annealed. hlngnetic when cold worhed Forging. Start forging at I I SO to I260 “C I 2 IO0 to 2.300 %b. Do not fores after forging stock drops helo\~ Y3 “C ( 1695 ‘%). Cool to black color;n less than 3 min. using liquid quench if necessarj
Recommended Normalizing. Annealing.
Heat Treating
Practice
Do not normalize
Anneal at 1010 to II?O”C t 1850 to 2050%~. For mu.ximum ductility and sotiness. use minimum annealing temperature of IO-IO ‘C ( 1905 “F). To guard against distortion of thin. delicate parts. lea\e ample room for expansion helLbeen parts. Stainless grades expand about IU ice 3s much as carbon and low-allo) steels. AIIou enough time for through heating after thermocouple has reached temperature. Stainless grades have approximately half the thermal conducti\ it! ofcarbon and lo\\-allo! steels. Choice of atmosphere depends on fitish dewed and 1%hethsr surface stock \rill he remo\sd. For bight annsaling. use \;~cuum or an atmosphere of h>droqen or dissociated ammonia at Deb pornt of -62 to -7-l ‘C t-80 to -100 %F,. Parts must he thoroughI> clean and dry Inert gases argon and helium (although expensive) and nitropen. with dew points of less than -5-l “C t-65 %. can he used. They lacb the reducing effect of hydrogen, so slight discoloration in the form of chrome oxide can result. Salt. esothsrnit. or endothermic atmospheres are satisfactory for nonhright annealing. Salt is difficult to remo\e. and rinw quenching at S9S ‘C ( I IO5 %I is not recommended. hecause interrupted quench at elevated temperature cannot he tolerated. Exothermic and endothemlic atmospheres must he carsfull~ controlled at equivalent carbon potential IO avoid carhurizntion. which will seriously lower corrosion resistance. Same prohlsm with atmosphere annealing. If oxidizing conditions are present. scale will form. DitTicult to remove in suhsequem descaling operations.
Cool rapidI! from annealing temperature: no more than 3 min to black color. Section size determines quenching medium: irater for heavy sections. air hllrst for mtrrmedinte sizes. and still air for thin sections. Carbides can precipitate at pram boundaries when parts are coolzd too slouly hetaeen 43 to 900 “C (795 to I650 %I. ln aerospace practice. parts are annealed at a set temperature of 1065 “C t I950 ‘)F) and quenched in Uurer \rith one exception: parts under 3.5 mm (0. IO in., thick ma! he air cooled or polymer quenched to minimize distortion. See table for soakin! times. Note: approval of the cognizant engineering orgamzation is rsqulred for annealing material in a strain-hardened condition. such as ‘12 hard: for stress relieving: or for dimensional stabilization. Heat treatmp or slow cooling unstabilized grades ktueen 470 to 8 IS “C t 875 to IS00 ~)F, is prohihited. except lbr 301L and 3 I6L stress Relieving. Pans can he relisved after quenching to achieve dimensmnal stahilitj. h! heating to 230 to 400 ‘C t-4-U to 750 ?) for up to several hours. depending on section sire and uithout change in metallographic wucture. In aerospace practice. parts are stress relieved ;II 900°C t 1650 @F), and quenched in \iater. A> an altemnti\c. parts may he stress relieved at annealing twiperatuw. Sections under 2.5 mm 10. IO in.) thick may he air cooled to minimize distortion. Parts fahrisntsd from steel in the strain-hardened condition. such ;1> I:> hard. shall not he stress relieved without permission of the so_rnirnnt-eligilissrincg authority. When stress relieving after irelding. hold for 30 min ntnimum at the stress relieving temperature. Heat treatmg or slo\r cooling of unstnhilized grades between 470 to 815 %I (875 to I SO0 ‘%J IS prohihltcd. rscept for 304L and 3 I6L. See table for Waking times
Nitriding. Not recommended. Case senousl~ impairs corrosion resistance in most media. Case seldom more than 0. I27 nun (0.005 in.) deep. Onl) used in specialized applications where material must he nonmagnetic and ha\e HS;IT-resiamt surface. If nitrided. parts must he in annealed condition IO prevent flaking or blistering of nitrided case. All sharp comers should he replaced u ith radii of not less than I .S9 mm (0.06 in.). Film of primail! chromium oxide. that protects stainless alloys from oxidation and corrosion. must he removed prior to nitriding. Accomplished by wet blasting. pickling. chemical reduction in reducing atmosphere. submersion in molten salt. or h! -one of weral proprietary processes. If doubt exists that complete and undorm dspnssivation has occurred. further reduction of the
Austenitic oxide may he accomplished in furnace hy means of reducing hydrogen atmosphere or suitable propriem agent. After depassivation. avoid conwnination of surface h2 finger or hand marking. Single-stage nitriding adequate at 525 to 550 C (975 to 1070 9) for 20 to 48 h (depending on case depth required). Dissociation rates for single-stage c>;cle are from 20 to 35%. Hardness is as high as 1000 to I350 HK on surface. 48-h cqclc produces case extending to 0. I27 mm (0.005 in. j with approximatel) 800 to 1000 HK. Case will rapidlq drop 10 200 HK core hardness. at approsimately 0. I65 mm (0.0065 in.)
Recommended
Processing
Cold work Anneal and quench Remove surface contamination Stress relieve Depassibate (if nitriding) Nitride (if required)
Sequence
(if required)
301:
Soaking
Times (Aerospace
Diameter or thickness(a) of maximum section mm (in.) inch&e “ptoxItO.ItJJ, o\~r2.50to6.2St0.I~U~tot~~SO1 over 6.25 IO I2 50 (0.30 to 0.500) over 12.50 10 25.00 (0.500 to I 00) o~er25OOro37.SOtl OOto 1.X)) o\cr 37.50 IO 50.00( I 50 to 2.00) over SO 0010 62.5Ot2.tWl tti 2.50) o~~rh’.SO~o75.0012.SOto 3.00) 0ver75.0013.00)
Stainless
Steels / 729
Practice)
Minimum soaking time Atmosphere furnace Salt bath min min 20 25 45 60 75 90 I05 120 It?)
17 18 35 -IO 4.5 SO 55 60 (c)
tar Thickness I\ mimmum dimension of hea\ iest section of part or nested load of parts. tbJ2.3 hplus 1Sm1n forc\q 12.Smm10.5 In.)orincremcnrof 12.5 mmtOSin.)over 7S mmt? in ) tc) I h. S nun plus 5 mm ftire\cq 12.5 mm10.S in.)ormcwmrntof 12.5 to.5 in.,o\cr7S mmt3 in.). Source. AhIS 27W-l
Austenitic
Chemical
Composition.
AISIjUNS
(S30200): 0. I5 c. XKI hln.
0.045 R 0.030 S. 1.00 Si. 8.00 to 10.00 Ni. 17.00 to 19.00 Cr
Similar Steels (U.S. and/or Foreign). AMS 5.515. 5516, 5636. 5637. 5688: ASME SAXO. SA479; ASTM A 176. AZ-IO. A313. A.314. A368. A473. A178. A-179. A492. A-%93. AS I I. ASS-I, A666: FED QQ-S763. QQ-S-766. QQ-W-473: hlL SPEC ML-S-862: SXE J230. J-IOS (30307-) Characteristics. slightly Slightly
Can be cold worked to high tensile strengths. hut with loner ductility than type 301. Nonmagnetic uhen annealed magnetic u hen cold worbed
Forging. Start forging at I I SO to I260 “C (2 100 to 2300 @F). Do not forge after forging stock drops helo\\ 92.5 ‘C t I695 ?). Cool to Mach color in lsss than 3 min. using liquid quench if necessq
Recommended Normalizing. Annealing.
Heat Treating
Practice
Do not normalize
Anneal at 1010 to I I30 “C I 1850 to 2050 ‘?j. To guard against distortion of thin. delicate pnrts. leave ample room for expansion between parts. Stainless grades expand about twice as much as carbon and lou-alloy steels. Allow enough time for through heating after thermocouple has reached temperature. Stainless grades hake approximately half the thermal conductivity of carbon and low-allo! steels. Choice of atmosphere depends on tinish desired and whether surface stock will he removed. For bright annealing. use vacuum or an atmosphere of hjdrogsn or dissociated ammonia at dew point of -62 to -7-l “C t-80 to -100 %). Parts must be thoroughly clean and dry. Inert gases argon and helium (although expensi\e) and nitrogen. with dew pomts of less than -5-I “C t-65 9). can be used. They lack the reducing effect of hydrogen. so slight discoloration in the form of chrome oxide can result. Salt. esothemic. or endothermic atmospheres are satisfxtory for nonhright annealing. Salt is difficult to remove. and rinse quenching at 595 ‘C t I IO5 ‘%) is not recommended. hecause interrupted quench at elevated temperature cannot be tolerated. Exothermic and endothermic atmospheres must he carefull) controlled at eyukalent carbon potential to avoid carburization. u hich uill seriou~l~ lower corrosion resistance. Same problem with atmosphere annealing. If oxidizing conditions are present. scale will fonn. Difficult to remove in subsequent descalincg operations.
Stainless
Steels / 729
Cool rapidI:\ from annealing temperature: no more than 3 min to black color. Section we determines quenching medium: water for heavy sections. air Mast for Intermediate sizes. and still air for thin sections. Carbides can precipitate at grain boundaries u hen parts are cooled too slowly between -125 to 900% 1795 to I650 ‘)F). In aerospace practice. parts are annealed at a set temperature of 1065 ‘C I 1950 9) and quenched in \\ater with one exception: parts under 2.5 mm iO.75 in.) thick ma> he air cooled or polymer quenched to minimize distortion. See table for soaking times. Note: approval of the cognizant engineering organization is required for annealing material in a strain-hwdened condition. such as !i hard: for stress relieving: or for dimensional stabilization. Heat treatin? or slow cooling unstabilized grades between -i70 to 8 IS “C t87S to IS00 9, ih prohibited, except for 304L and 3 l6L %X?SS RekVing. Parts can be rslie\ed after quenching to achieve dimensional stability. b) heating to 230 to 400 ‘C (-US to 750 ?) for up to sebsral hours. depending on section size and without change in metallographic structure. In aerospncs practice. parts are stress relieved at 900 “C (I650 OF), and quenched in crater. .A\ an altemati\e. parts may be stress relieved at annealing temperatures. Sections under 2.5 mm (0. IO in.) thick may he air cooled to minimize distortion. Parts fabricated from steel in the strain-hardened condition. such as ‘(‘2 hard. shall not he stress relieved without permission of the cognizant engineering authorit!. When stress relieving afier ~+rllding. hold for 30 min minimum at the stress relieving temperature. Heat treatins or slow cooling ofunstabilized grades between470 to 815 “C (875 to IS00 “Ft is prohibited. except for 304L and 316L. See table lix soaking times
Nitriding. Not recommended. Case seriously impairs corrosion resistancc in mozt media. Case seldom more than 0. I27 mm (0.005 in.) deep. Only used In specialized applications u here material must be nonmagnetic and ha\? \rear-resistant surface. If nitrided. parts must be in annealed condition to prevent M.ing or blistering of nkrided case. All sharp comers should be replaced with radii of not less than I.59 mm (0.06 in.). Film of primarily chromium oxide. that protects stainless alloys from oxidation and corrosion. must be removed prior to nitridinp. Accomplished by uet blasting. pickling. chemical reduction in reducing atmosphere. suhmersion in molten salt. or h\. one of se\sral proprietag processes. If douht exists that compkts and un:foml depassivation has occurred. further reduction of the oxide ma> he accomplished in tilmnce h> means of reducing hjdropen
730 / Heat Treaters
Guide
atmosphere or suitable proprietary agent. After depassivation. avoid contamination of surface by finger or hand marking. Single-stage nitriding adequate at 525 to 550 “C (975 to I020 “FL 20 to 38 h (depending on case depth required). Dissociation rates for single-stage cycle, from 20 to 35%. Hardness is as high as 1000 to IX0 HK on surface. 18-h cycle produces case extending to 0. I27 mm (0.005 in.) with approximateI) 800 to 1000 HK. Case will rapidly drop to 200 HK core hardness, at approximateI> 0. I65 mm (0.0065 in.)
Recommended l l l l l l
Processing
Cold work Anneal and quench Remove surface contamination Stress relieve Depassik ate (if nitriding) Nitride (if required)
302: Microstructures.
Sequence
(if required)
302:
Soaking
Times (Aerospace
Diameter or thickness(a) ofmaximum section mm (in.) inclusive
o~er2.SOto6.2S(0.100to0.2SO~ o\er 6 25 to 12.50 (0.250 ICI0.500’1 over 12.50 to 25.00 (O.SOO10 I .OO:i owr ?XoO to 3750 ( I .OUto 1.50) o\er 3750 10SO.00( I.50 to 1.OOl merSO.OOro62 50(2.00m1?.50) over62.50107.5.00(2.~0to3.00) mer75 OO(3.00)
Practice)
Minimum Atmosphere furnace min 20 25 45 60
75 90 105 I 20 (b)
soaking
time
Salt bath mill
17 18 35 40 45 50 55 60 (Cl
la) Thrckness is minimum dimension of heaviest section of pari or nested load of parts. Ib)2.2.( hplus I.5 minforekery 12.5mm(O.Sin.)orincrementof lXmm(0.5in.)over 75mmt3in.).(c) I h.SminplusSninfore~er) 12.Smm(O.Sin.)orincremenrof 12.5 (0.5 in.)over 75 mm (3 in ). Source: AMS 27591-t
(a) Electrolytic: 10% sodium cyanide, 500x. Strip, 1.56 mm (0.062 in.) thick. Annealed at 1065 “C (1950 OF).Cooled rapidly to room temperature. Ferrite pools (globules) in austenite matrix. (b) Electrolytic: 10% sodium cyanide, 500x. Containing 0.15 carbon. Sensitized 1 h at 650 “c (1200 “F). Etched 5 min. Almost continuous network of carbide at austenite grain boundaries. (c) Electrolytic: 10% chromic acid, 500x. Same as (b), except etch was in 10% chromic acid for l/2 min. Grain-boundary carbide network, twinning, and evidence of carbon diffusion within austenite grains
730 / Heat Treaters
Guide
302B Chemical COInpOSitiOn. AISI/UNS (S30215): 0.1s C. 2.00 hln. 0.045 P.0.03 S. 2.0 to 3.0 Si. 8.0 to 10.0 Ni. 17.00 to 19.00 Cr Similar
Steels (U.S. and/or
Foreign).
ASTM A I 67. X76. ~3 14.
A-i73. A580: SAE MO5 (30302 B)
Characteristics.
Resistance to scaling at elevated temperaNreS superior to type 302 because of added silicon. Nonmagnetic when annealed. Slightly magnetic when cold worked
Forging. Start forging at I I10 to I230 “C (3050 to 22-15 “F). Do not forge after forging stock drops below 925 “C t I695 9). Cool to black color in less than 3 min. using liquid quench if necessary
Recommended Normalizing.
Heat Treating
Practice
Do not normalize
Annealing. Anneal at 1010 to I I20 “C ( I850 to 2050 9). For masimum ductility and softness. use a minimum annealing temperature of IO-IO “C ( 1905 OF). To guard against distortion of thin. delicate parts. leave ample
room for expansion betueen parts. Stainless grades expand about twice as much as carbon and low-alloy steels. Allow enough time for through heating after thermocouple has reached temperature. Stainless grades have approximately half the thermal conductivity of carbon and low-alloy steels. Choice of atmosphere depends on finish desired and whether surface stock will be removed. For bright annealing. use vacuum or an atmosphere of hydro en or dissociated ammonia at dew point of -62 to -74 ‘C (-80 to -100 4 ). Parts must be thoroughly clean and dry. Inert gases argon and helium (although expensive) and nitrogen. with dew points of less than-54 ‘C (-65 %). can be used. They lack the reducing effect of hydrogen. so slight discoloration in the form of chrome oxide can result. Salt, exothermic. or endothermic atmospheres are satisfactory for nonbright annealing. Salt is difficult to remove. and rinse quenching at 595 ‘C (I I05 “F, is not recommended, because interrupted quench at elevated temperature cannot be tolerated. Exothetmic and endothermic atmospheres must be carefully controlled at equivalent carbon potential to avoid carburization. which will seriously lower corrosion resistance. Same problem with atmosphere annealing. If oxidizing conditions are present. scale will form. Difftcult to rrmove in subsequent dcscaling operations.
Austenitic Cool rapidly from annealing temperaNre; no more than 3 min to black color. Section size determines quenching medium: water for heavy sections, air blast for intermediate sizes. and still air for thin sections. Carbides can precipitate at grain boundaries when parts are cooled too slowly between 425 to 900 ‘C (795 to I650 OF). In aerospace practice. parts are annealed at a set temperature of 1065 ‘C (1950 OF) and quenched in water with one exception: parts under 2.5 mm (0. IO in.) thick may be air cooled or polymer quenched to minimize distortion. See table for soaking times. Note: approval of the cognizant engineering organization is required for annealing material in a strain-hardened condition. such as ‘I’.‘. hard; for stress relieving; or for dimensional stabilization. Heat treating or slow cooling unstabilized grades betueen 170 to 8 IS ‘C (875 to I500 “F, is prohibited. except for 303L and 3 IhL Stress Relieving. Parts can be relieved after quenching to achieve dimensional stability. by heating to 230 to -100 ‘C (US to 750 ‘%) for up to several hours. depending on section size and without change in metallographic structure. In aerospace practice. parts are stress relieved at 900°C (I 6SODF), and quenched in water. As an alternative. parts may be stress relieved at Sections under 2.5 mm (0. IO in.) thick ma> be air annealing IemperaNreS. cooled to minimizedistortion. Parts fabricated from steel in the strain-hardened condition. such as t/z hard. shall not be stress relieved without permission of the cognizant engineering authorit). When stress relieving after welding. hold for 30 min minimum at the stress relieving temperature. Heat treating or slow cooling of unstabilized grades between 470 to 8 IS ‘C (875 to 1500 ‘%) is prohibited, except for 304L and 316L. See table for soaking times Not recommended. Case seriously impairs corrosion resistance in most media. Case seldom more than 0. I27 mm (0.005 in.) deep. Only used in specialized applications where material must be nonmagnetic and have wear-resistant surface. If nitrided. parts must be in annealed condition to prevent flaking or blistering of nitrided case. All sharp comers should be replaced with radii of not less than I .S9 mm (0.06 in. j. Film of primarily chromium oxide. that protects stainless alloys from oxidation and corrosion. must be removed prior to nitriding. Accomplished by uet blasting. pickling, chemical reduction in reducing atmosphere. submersion in molten salt. or by one of several proprietary processes. If doubt exists that
Steels / 731
complete and uniform depassivation has occurred. further reduction of the oxide may be accomplished in furnace by means of reducing hydrogen atmosphere or suitable proprietary agent. After depassivation. avoid contamination of surface b2 finger or hand marking. Single-stage nitriding adequate at 525 to 550 C (975 to 1020 T) for 20 to 48 h (depending on case depth required). Dissociation rates for single-stage cycle are from 20 to 35%. Hardness is as high as 1000 to 1350 HK on surface. 48-h cycle produces case extending to 0. I27 mm (0.005 in.) with approximately 800 to 1000 HK. Case will rapidly drop to 200 HK core hardness, at approximately 0. I65 mm (0.0065 in.)
Recommended
Processing
Cold work Anneal and quench Rcmoke surface contamination Stress relieve Depasslvate (if nitriding) Nitride (if required’)
3028:
Soaking
Sequence
(if requiredj
Times (Aerospace
Diameter or thickness(a) of maximum section mm (in.) inclusive o~er2..50t06.25(0.100ro0250~ over 6.25 to 11.50 (0.250 IO 0 500)
Nitriding.
Stainless
over 12.50 to 25.00 (0.500 Lo I .OO) o~er~SOOto37.SOtl OOro 1.50) over 37.50 10SO.00t I..50 to 1.00) over SO00 to 62.50 t2.CMlto 2.50) over61.50 to75 OOt2.50 to 3.00) over75.00t3.00)
Practice)
hlinimum Atmosphere furnace min
10 2s 4s 60 75 90
105 120 (b)
soaking
time Salt bath min 17 18 35 40 45 SO 55 60 (C)
(a) Thickness is minimum dimension of hea\ iejl section of part or nested load of parts. th)Z.ZS hplus lSminfore\ery 12.Smmt0.Sin.)orlncr~mrntof l?.Smm(OSin.)over 75 mm(3 in j.(c) I h.Sminplus Smin forever) 12.5 mm(O.5 in.)orincrementof 12.5 (0.5 m.)o\cr75 mmt.l in.). Source. AhlS 27591-1
Austenitic
Stainless Steels / 731
303 Chemical Composition. 0.2OOP.O.lSOSmin. (optional)
AISI/UNS
l.OOSi.8.OOto
(~30300): o. IS c. XKI Mn.
lO.OONi.
17.OOto 19.00Cr.0.60Mo
Similar Steels (U.S. and/or Foreign). MS 5640 (I ); ASME SA194.SA320:ASTMA193.A314A320,A473.A581,A582; hlfLSPEC MB-S-862: SAE J-t05 (30303): (Ger.) DIN 1.13OS; (Fr.) AFNOR Z IO CNF 18.09: (Ital.) UNI X IO CrNiS I8 09; (Jap.) JIS SUS 303: (Swed.) SSIJ 3346; (U.K.) B.S. 303 S 21 Characteristics. The addition of sulfur aids machinability. Used to minimize seizing or galling. Must be annealed after welding. Suitable for use in automatic screw machines. Less resistant to corrosion than other 300 steels. Shows good resistance to oxidation up to 925 ‘C ( 1695 9) Forging. Start forging at I I50 to 1290 “C (2100 to 2355 “F). Finish forging at 925 to 955 “C ( I695 to I750 ?). Cool to black color in less than 3 min. using liquid quench if necessary Recommended Normalizing.
Heat Treating
Do not normalize
Practice
Annealing.
Anneal at 1010 to I I20 “C (I850 to 2050 ‘%). To guard against distortion of thin. delicate parts. leave ample room for expansion between parts. Stainless grades expand about twice as much as carbon and Ion -alloy steels. Allow enough time for through heating after thermocouple has reached temperature. Stainless grades have approximately half the thermal conducti\ ity of carbon and low-alloy steels. Choice of atmosphere depends on tinish desired and u hethcr surface stock will be removed. For bright annealing. use vacuum or an atmosphere of hydrogen or dissociated amrnoma at dew point of -62 to -7-l “C (-80 to -100 %. Parts must be thoroughly clean and dry. Inert gases argon and helium (although expensive) and nitrogen. with den points of less than -5-l “C (-65 ‘%). can be used. They lack the reducing effect of hydrogen. so slight discoloration in the fomr of chrome aside can result. Salt. exothermic, or endothermic atmospheres are satisfactory for nonbright annealing. Salt is difftcult to remove. and rinse quenching at 595 ‘C (I IO5 ‘%) is not recommended, because interrupted quench at elevated temperature cannot be tolerated. Exothermic and endothermic atmospheres must be carefully controlled at equivalent carbon potential to avoid carburization. which will seriously lower corrosion resistance. Same problem with atmosphere annealing. If oxidizing conditions are present. scale will form. Difficult to remove in subsequent descaling operations.
732 / Heat Treaters Guide Cool rapidl! I’rom annealing temperature: no more than 3 nun to black color. Section size determines quenching medium: eater for heavy sections. air blast for intermediate sizes. and still air for thin sections. Carbides can precipitate at main boundaries u hen parts are cooled too slowly between 33 to 9OO“C (795 to 1650 @F,. In aerospace practice. parts are annealed at a set temperature of 1065 “C (I950 ‘$1 and quenched in uater with one exception: parts under 7.5 mm ((I IO in.) thick may be air cooled or polymer quenched to minimize distortion. See table for soaking times. Note: approval of the cognizant engineenng organization is required for annealing matenal in a strain-hardened condition. such as ‘,i hnrd: for stress relieving: or for dimensional stabilization. Heat treating or slot\ cooling unstabilized grades bstuern -170 to 8 IS “C (875 to IS00 “F) is prohibited. except for JO-IL and 3 l6L
Stress Relieving. Parts can be relieved after quenching to achieve dimensional stability. by heating to 230 to 400 “C (US to 750 “F) for up to several hours. depending on section sizr and without change In metallographic structure. In aerospace practice, parts are stress relieved at 900 “C t 1650’~). and quenched in water. As an altsmnti\e. parts may be stress relieved at annealing temperatures. Sections under 3.5 mm (0. IO in.) thick may be air cooled to minimize distortion. Parts fabricated from steel in the strain-hardened condition. such as ‘/i hard. shall not be stress relieved uithout pennission of the cognizant engineering authority. \I’hcn stress rclie\ ing after welding. hold for 30 min nunimum at the stress relieving temperature Heal treating or slow cooling of unstabilized grades beween 470 to 8 IS “C (875 to IS00 %) is prohibited. except for JO-IL and 316L. See table for soahing times Nitriding.
Not recommended. Case seriously impairs corrosion rkstance in most media. Case seldom more than 0. I27 mm (0.005 in.) deep. Only used in specialized applications u here material must be nonmagnetic and have \tear-resistant surface. If nittided. parts must be in annealed condition to pre\ent flaking or blistering of nitrided case. All shnrp comers should be replaced with radii of not less than I.59 mm (0.06 in.). Film of primarily chromium oxide. that protects stainless alloys from osidation and corrosion. must be removed prior to nitriding. Accomplished by uet blasting. pickling. chemical reduction in reducing atmosphere. submersion In molten salt. or by one of several proprietary processes. If doubt exists that
complete and uniform depassivation has occurred. further reduction of the oxide may be accomplished in furnace by means of reducing hydrogen atmosphere or suitable proprietary agent. After depassivation. avoid contamination of surface by finger or hand marking. Single-stage nitriding adequate at 525 to 550 ‘C 1975 to 1020 “F for 20 to 48 h (depending on case depth required). Dissociation rates for single-stage cycle are from 20 to 3% Hardness is as high as IO00 to I350 HK on surface. 48-h cycle producrs case extrnding to 0. I27 mm (0.005 in.) with approximately 800 to 1000 HK. Case nilI rapidly drop IO 30 HK core hardness. at approximately 0. I65 mm (0.0065 in.)
Recommended l l l l l l
Processing
Cold uork Anneal and quench Remove surface contamination Stress relieve Depassivate (if nitriding) Nitride (if required)
303:
Sequence
(if required)
Soaking Times (Aerospace Practice)
Diameteror
thickness(a)
of masimum section mm (in.) incluske
o~~~-?..iOr"tr.~.i~0.I~X)lo~.~~o,
ober 6.25 to 12.50 (0.150 IO 0.500) over 12.50 to 25.00 (0.500 to 1.00) oter 2S.GOto 37 SOI I .00to I SO, o~er~7.SOto50t~~tI.SOto200~ over SO.00 to 61.50 I2 00 to 2.501 o\~rh~.S0to7SOOt~.SOto300~ o\rr75.of~l.woI (III Thtchnes 1bt2.25hplus 7Smntt!in.) (0.5 in lo\er
Minimum Atmosphere furnace min 20 3 -I5 60 7s YO 105 120 tbl
soaking
time Salt batb min I7 I8 35 40 45 SO 55 60 (C)
i> mimmum dtmcnslon of hea\ iest section of part or nested load of parts. ISnunforevc~ I:! Smm(OSin )orincrementofl2.5mmtO.Sin )over ICI I h.SmtnplusSnlinfore~eq II 5mmtO.Sin.)orincrementof 12.5 75 mm t 3 in ). Source: .AhlS 27591-l
732 / Heat Treaters
Guide
303Se Chemical Composition. AISI~~MS (~3032.3): 0.1s C. 2.00 htn. 0.200 P.O.06OS min. l.OOSi. 8.Oto 10.0 Ni. 17.0 to 19.0Cr. 0.15 Se Similar Steels (U.S. and/or Foreign). AhlS 5610 (Type 2). 5641. 5738: ASME WI94 SA320: ASTAI A 19-t. .A314. .A3?0. .4-!73. AS8 I. ,458’: hlIL SPEC MlL-S-86’: SAE J4OS (30303 Se, Characteristics. Selenium addition promotes mochinahility. Lrsed to minimize seizing or galling. hlust be annealed after \belding. Suitable for use in automatic scre\v machines. Less resistant to corrosion than other 300 steels, Shows good resistance to oxidation up to 925 “C I I695 “FF, Forging.
Start forgmg at I IS0 to 1290 “C t2100 to 1355 “Ft. Finish forS,ing at 935 to 955 ‘C t I695 to I750 9). Cool to black color in less than 3 mm. using liquid quench if necessary
Recommended Normalizing. Annealing.
Heat Treating
Practice
Do not normalize
Anneal at 1010 to I I20 “C t 1850 to 2050 OF). To guard against distortion of thin. delicate parts. leave ample room for expansion between parts. Stainless grades expand ahout twice as much as cnrhon and
lou-nlloy steels. AIIou enough time for through heattngafterthermocouple has reached temperature. Stainless grades hove approximately half the themral conducti\ ity of carbon and lou-alloy steels. Choice of atmosphere depends on finish desired and whether surface stock will be removed. For bright annealing. use 1 acuum or an atmosphere of hydrogen or dissociated ammonia at deu point of -62 to -7-t “C t-80 to -100 m. Parts must be thoroughly clean and dry. Inert gases argon and helium (although expenstvet and nitrogen. with dew points of less than -5-t “C f-65 %). can bc used. They lack the reducing effect of hydrogen. so slight discoloration in the form of chrome okids can result. Salt. exothermic. or endothermic atmospheres are satisfactory for nonbright annealing. Salt is difficult to remo\e. and rinse quenching at 595 ‘C (1 IO5 ?j is not recommended. because interrupted quench at ekated temperature cannot be tolerated. E\othemlis and endothemtic atmospheres must be carefully controlled at equivalent carhon potential to avoid cnrhunzation. which will seriously lo\rer corrosion resistance. Same problem with atmosphere annealing. If oxidizing conditions are present. scale will form. Difficult to remove in subsequent descaling operations. Cool rapidI! from annealing temperature; no more than 3 mm to black color. Section size detemlines quenching medium: water for heavy sections. air blast for intemrsdiate sizes. and still air for thin sections. Carbides
Austenitic
can precipitate at grain houndaries when parts are cooled too slo\rly betueen -US to 900 “C (795 to I650 “n. In aerospace practice, parts are annealed at a set temperature of 1065 ‘C. (I950 “F) and quenched in water with one exception: parts under 2.5 mm (0. IO in.) thick may be air cooled or polymer quenched to minimize distortion. See table for soaking times. Note: approval of the cognizant engineering organization is required for annealing material in a strain-hardened condition. such as t/I hard: for stress relieving,; or for dimensional stabilization. Heat treating or slow cooling unstabilized grades between -I70 to 815 ‘C (875 to I SO0 %) is prohibited. except for 3ML and 3 16L stress RelieVing. Parts can he relieved after quenching to achieve dimensional stability. by heating to 730 to -KM “C (4-15 to 750 ‘%) for up to several hours. depending on section size and without change in metallographic structure. In aerospace practice. parts are stress relic\ ed at 900 ‘C ( 1650 9). and quenched in water. As an alternative. parts may be stress relieved at annealing, temperatures. Sections under 2.5 mm (0. IO in.) thick may be au cooled to minimize distortion. Parts fabricated from steel in the strain-hardened condition. such as t/z hard. shall not be stress relieved without permission of the cognizant engincerinp authority. When stress relieving after welding. hold for 30 min minimum at the stress relieving temperature. Heat treating or SIOH cooling of unstabilized grades between 170 to 815 “C (875 to 1500 v) is prohibited. except for 3O-tL and 316L. See table for soaking times
Nitriding.
Not recommended. Case seriously impairs corrosion resistance in most media. Case seldom more than 0. I17 mm (0.005 in.) deep. Only used in specialized applications where material must be nonmagnetic and have wear-resistant surface. If nitrided. parts must be in annealed condition to prevent flaking or blistering of nitrided case. All sharp comers should be replaced u ith radii of not less than I .S9 mm (0.06 in.). Film of primarily chromium oxide, that protects stainless alloys from oxidation and corrosion. must he removed prior to nitriding. Accomplished by wet blasting. pickling, chemical reduction in reducing atmosphere. submersion in molten salt, or by one of several proprietary processes. If doubt exists that complete and unifoml depassivation has occurred, further reduction of the oxide may be accomplished in furnace by means of reducing hydrogen
Stainless
Steels / 733
atmosphere or suitable proprietary agent. After depassivation, avoid contamination of surface hv tinger or hand marking. Single-stage nitriding adequate at 525 to 550 “C (975 to 107-O “n for 20 to -18 h (depending on case depth required). Dissociation rates for single-stage cycle are from 20 to 3Spi. Hardness is as high as 1000 to 1350 HK on surface. 48-h cycle produces case extending to 0. I27 mm (0.005 in.) with approximately 800 to IO00 HK. Case Lvill rapidly drop to X0 HK core hardness. at approximately 0. I65 mm (0.0065 in.)
Recommended l l l l l l
Processing
Cold work Anneal and quench Remove surface contamination Stress relieve Depassivate tif nitriding) Nitride iifrequircd)
303Se:
Soaking
Sequence
tif required)
Times (Aerospace
Diameter or thickness(a) of masbnum section mm (in.) inclusive up to 2 so10 loo) okc2.50 roh.3 ~O.100 to0 Xl) over 6.25 10 Il.50 [O.?SO IO 0.500) over II 50 to 25.00 10.500 to 1.00) 0~rr~S.00t037.50~1 0010 1.50) oter 37.5O1050.001 LSO IO 2.&J) o\ er 50.00 to 630 I 2.00 IO 30) o~er62SOto7500~250to300~ o~er75OOtZ.00~
Practice)
Miuimum Atmosphere furnace miu 20 IS 45 60 75 90 IO5 I20 ib,
soaking
time Salt batb miu 17 18 35 JO 4.5 50 55 60 (Cl
I 31 Tlushnec~ 15 minimum dimension of hcu\ iest reslion ofpar~ or nested load of parts 1b,2.?Shplus 15miniorc\q 12.5mn~~0.5in.)orincrrmentof13nun(0.5in.)o~rr 75mmlZin.l ICI I h..inlinpluj5mln~~rl\cr) 12.~~i~,~0.5in.~orincrenicnrofI2.S (0 5 rn ,o\er75 mm I3 in.) Source .AhlS 275911
Austenitic
Stainless
Steels I733
304 Chemical Composition. AISI/LlNS (S30400): 0.08 C. 2.00 hln. 0.0-E P. 0.030 S. 1.00 Si. 8.0 to IO.5 Ni, 18.0 to 20.0 Cr Similar
Steels (U.S. and/or
Foreign).
AhlS 5501, 55 13, ~60.
S56S.SS66.5567,5639.S697; AShlE S.4 182. SA 191 i8r. S.42 13. S.4210, SA249. SA312, SA320 tB8i. S.4358. S.4376. S.4-tO.I. SA?OY, S.4-130. S.4179. S.4688; ASThl .4 167. A 182, A 193, .4 19-I. A2 13. .4X0. .4249, 44369. A270. A27 I. A276. .43 12. A3 13. A3 I-1. A320. A368. ,437h. .UO9. A-IX). A173. AA7X. A-179. A-t’)‘. .4193. A5 I I. ASS-+. AS8O. A632. A65 I. 84666. 84688: FED QQ-W-423. Q763. QQ-S-766. STD-66; hllL SPEC MlL-F-30138. MJL-S-86’. MIL-S-5059. hlIL-S-33195. hlIL-S-23 lY6. IkIlL-T-68-tS. MIL-T-8504. hllL-T-8506; WE J-t05 t3030-t~: tGer.t DIN l.-I301; (Fr.) AFNOR Zh CN 18.09; (Ital.) UNI X 5 CrNi I8 IO; c’Jap.1 JIS SW 30-t: 6wed.j SSIJ 2332; (U.K.) B.S. 30-t S IS. 302 S 17. 30-t S 16. 30-l S 18.30-t S 25.3W S -10. En. 58 E
Characteristics.
Corrosion resistance higher than type 302. Nonmnpnetic n hen annealed. Slightly magnetic n hen cold marked. Less susceptible to precipitation ofcarhides during ueldinp
Forging. Start forging at I I SO to I260 ‘C 12 100 to 2300°F)). Do not forge after iorging stock drops helo\s 925 ‘C (I 695 ‘F). Cool to Hack color in less than 3 mm. using liquid quench if necessary
Recommended Normalizing.
Heat Treating
Practice
Do not nonnahzs
Annealing. .Anneul at 1010 to I I20 “C ( I850 to ?OSO’%). For maximum ductility and softness. use a minimum annealinp temperature of IO30 ‘C i 1905 ‘%). To guard against distortion of thin. delicate parts, leave ample room for espansion between parts. Stainless grades expand ahout twice as much as carbon and low-alloy steels. .Allow enough time for through heating after thcrmocouplr has reached temperature. Stainless grades have approximately half the thermal conducti\ ity ofc‘arbon and low-alloy steels. Choice of atmosphere depends on finish desired and whether surface stock will he removed. For bright annealing. use vacuum or an atmosphere of hydra en or dissociated ammonia at dew point of -62 to -7-t ‘C t-80 to -IO0 4 r. Parts must be thoroughly clean and dry. Inert gases argon and helium talthough eupsnsivet and nitrogen. \vith dew points of less than -54 “C t-65 ‘Ft. can be used. They lack the reducing effect of hydrogen. so slight discoloration in the fomt of chrome oxide can result. Salt, exothernit. or cndothemic atmospheres are satisfactory for nonbright annealing. Salt is difficult to remove. and rinse quenching at 595 ‘C (I IO5 “F) is not recommended. hecause interrupted quench at elevated temperature cannot be tolerated. Exothermic and endothrmtic atmospheres must be carefully controlled at equi\ alent carbon potential to avoid carhurization. which will
734 / Heat Treaters
Guide
seriously lower corrosion resistance. Same problem with atmosphere annealing If oxidizing conditions are present, scale will form. Difficult to remove in subsequent descaling operations. Cool rapidly from annealing temperature; no more than 3 min to black color. Section size determines quenching medium: water for heavy sections. air blast for intermediate sizes, and still air for thin sections. Carbides can precipitate at grain boundaries when parts are cooled too slowly between 425 to 900 “C (795 to I650 ‘%). In aerospace practice. parts are annealed at a set temperature of 1065 “C (1950 “F, and q uenched in water with one exception: parts under 2.5 mm (0. IO in.) thick may be air cooled or polymer quenched to minimize distortion. See table for soaking times. Note: approval of the cognizant engineering organization is required for annealing material in a strain-hardened condition, such as t/J hard; for stress relieving; or for dimensional stabilization. Heat treating or slow cooling unstabilized grades between 470 to 8 IS ‘C (875 to IS00 “F, is prohibited. except for 304L and 3 l6L Stress RelieVing. Parts can be relieved after quenching to achieve dimensional stability, by heating to 230 to 300 “C (445 to 750 “F, for up to several hours, depending on section size and without change in metallographic structure. In aerospace practice, parts are stress relieved at 900 “C ( 1650 ?). and quenched in water. As an alternative, parts may be stress relieved at annealing temperatures. Sections under 2.5 mm (0. IO in.) thick may be air cooled to minimize distortion. Parts fabricated from steel in the strain-hardened condition, such as t/2 hard, shall not be stress relieved without permission of the cognizant engineering authority. When stress relieving after welding, hold for 30 mitt minimum at the stress relieving temperature. Heat treating or slow cooling of unstabilized grades between 470 to 8 IS ‘C (875 to 1500 %) is prohibited, except for 304L and 3 I6L. See table for soaking times
304: Microstructures.
Nitriding. Not recommended. Case seriously impairs corrosion resistance in most media. Case seldom more than 0.127 mm (0.005 in.) deep. Only used in specialized applications where material must be nonmagnetic and have wear-resistant surface. If nittided, parts must be in annealed condition to prevent flaking or blistering of nitrided case. All sharp comers should be replaced with radii of not less than I .59 mm (0.06 in.). Film of primarily chromium oxide. that protects stainless alloys from oxidation and corrosion, must be removed prior to nitriding. Accomplished by wet blasting. pickling, chemical reduction in reducing atmosphere. submersion in molten salt. or hy one of several proprietary processes. If doubt exists that complete and uniform depassivation has occurred, further reduction of the oxide may he accomplished in furnace by means of reducing hydrogen atmosphere or suitahle proprietary agent. After depassivation, avoid contamination of surface by finger or hand marking. Single-stage nitriding adequate at 525 to 550 ‘C (975 to 1020 “n for 20 to 48 h (depending on case depth required). Dissociation rates for single-stage cycle are from 20 to 35%. Hardness is as high as 1000 to 1350 HK on surface. 48-h cycle produces case extending to 0.127 mm (0.005 in.) with approximately 800 to 1000 HK. Case will rapidly drop to 200 HK core hardness, at approximately 0. I65 mm (0.0065 in.)
Recommended l l l l l l
Processing
Cold work AMeal and quench Remove surface contamination Stress relieve Depassivate (if nitriding) Nitride (if required)
Sequence
(if required)
(a) HNO,-acetic-HCI-glycerol, 250x. Strip. Annealed 5 min at 1065 “C (1950 “F). Cooled in air. Equiaxed austenite grains and annealing twins. (b) Electrolytic: 10% oxalic acid, 100x. Forging. Annealed at 1065 “C (1950 OF), 1 h. Quenched in water. Irregular austenite grains. Etch pits at dispersed carbide particles. (c) Electrolytic: HNO,-acetic, then 10% oxalic acid, 100x. Strip. Annealed 2 min at 1065 “C (1950 OF). Air cooled. Equiaxed austenite grains (ASTM No. 8) annealing twins, small stringer inclusions. (d) Electrolytic: 10% oxalic acid, 500x. Strip. Annealed at 1040 “C (1905 “F). Sensitized by reheating at 650 “C (1200 OF), 1 h. Carbide precipitation at grain boundaties and at twin boundaries. (e) Boiling Murakami’s reagent, 500x. Plate with 0.062 carbon content. Annealed for carbide agglomeration by being held at 1065 “C (1950 “F), 1 h. Sensitized by cooling to 600 “C (1475 “F) and held at temperature, 100 h. Water quenched. Precipitation of chromium carbide at austenite grain boundaries
Austenitic 304:
Soaking
Times (Aerospace
Diameter or thickness(a) of maximum section mm (in.) inclusive
upt02.50~0.100~ over 2.50 to 6 25 (0. IOU to 0.2S01 o\er 6.15 to 12.50 (0.250 to 0.500) o\er 12.50 to 25.00 (O.SOO to I .OO) over 3.00 to 37.50 I I.00 to I.SO) orer 37.50 to 50.00 ( I .so to 2.00, merS0.00 to62.SOC?.OO to 250) over62.50 to 75.00(2.50 to 3.00) o~er75.00(3.00)
Practice)
304: Precipitation
Minimum soaking time Atmosphere furnace Salt bath min min 20 2s -Is 60 75 90 10s 120 tb)
17 18 3s 10 4s SO 5.5 60 Ic)
(a) Thte);nejs is minimum dimension of heaviest section of part or nested load of par& (b)225hplus ISminforevery 12.5mm(O.Sin.)orincrementof 12.SmmtO.Sin.)o~er 75 mmI3in.).(c) I h.SminplusS min foretery I2 5 mm(0.S in.)ormcrementof 12.5 to.5 in.bover75 mm(3 in.). Source: AhlS 2759/A
Stainless
Steels / 735
Diagram. Composition: 0.05 C. 1.73 Mn, 0.60 Si. 0.026 P. 0.012 S, 9.0 Ni, 18.7 Cr, 0.026 N. Solution treated at 1050 “C (1920 “F) for 30 min, water quenched, aged at 600 to 800 “C (1110 to 1470 “F) for up to 50,000 h
Austenitic
Stainless Steels / 735
304H Chemical Composition.
~rsr/uNS
(S30.409): 0.03 10 0. I 0 C. LOO
Mn. 0.035 P, 0.03 S. 1.00 Si. 8.0 to IO.5 Ni. 18.0 IO 20.0 Cr
Recommended Heat Treating Annealing. ln aerospace practice, parts
Practice
are annealed at a set temperature of 1065 ‘C (1950 OF) and quenched in water with one exception: parts under 2.5 mm (0. IO in.) thick may be air cooled or polymer quenched to minimize distortion. See table for soaking times. Note: approval of the cognizant engineering organization is required for annealing material in a strain-hardened condition. such as ‘1~ hard; for stress relieving: or for dimensional stabilization. Heat treating or slow cooling unstabilized grades between 470 to 8 IS “C (875 to IS00 “n is prohibited, except for 30-&L and 316L Stress RdieVing. In aerospace practice, parts are stress relieved at 900 “C ( 1650 %). and quenched in water. As an alternative, parts may be stress relieved at annealing temperatures. Sections under 2.5 mm (0. IO in.) thick may be air cooled to minimize distortion. Parts fabricated from steel in the strain-hardened condition, such as l/r, hard. shall not be stress relieved without permission of the cognizant engineering authority. When stress relieving after welding, hold for 30 min minimum at the stress relieving temperature. Heat treating or slow cooling of unstabilized grades between
470 to 815 ‘C (875 to 1500 “F) is prohibited. See table for soaking times
304H:
except for 304L and 316L.
Soaking Times (Aerospace Practice)
Diameter or thickness(a) of maximum section mm (in.) inclusive “pl02.50~0.100) o~er2.~0to6.2~~O.I~X)to0.250~ over 6.25 IO lr!.SO (0.30 IO 0 500) ow 12.50 to 25.00 10.500 w I.001 o\erl500to37.SOtl.00to 1.50, over 37.50 to 50.00 ( I.50 to 2.00’ o\~erSO.W to62 SO 12.00 to 2.50) o~er67.SOto7S.(X)(‘.50103.(H), 0ver7.5.00~3.00~
Minimum Atmosphere furnace min 20 25 15 60 7s 90 IO.5 110 rbj
soaking
time Salt batb min 17 18 35 40 35 SO 55 60 (C)
(3) Thickness is minimum dimension of heat iest section of part or nested load of parts. ib,2.15 hplus 15minforckery 12.SmmtO.Sin.~orincrementof 12.5mm(O.Sio.)over 75 mm 13 in.). IC‘) I h. SmmplusS minforetery 12.5 mtn(O.5 in.)orincrementof 12.5 (0 5 m.)over75 mm 13 in.1 Source: 4hlS 27591-l
Austenitic
Stainless Steels / 735
304L Chemical Composition.
AISI/UN.S (S30403):0.03 C, 2.00 hln.
0.045 P. 0.030 S. I .OO Si. 8.0 to 12.0 Ni. 18.0 to 20.0 Cr
Similar Steels (U.S. and/or Foreign). SA 182, SA2 13, SA240. SA239. A 167. A 182, A2 13. A2-lO. A249. A379, A5 I I, A554, A580. A632 SPEC MB/S-862, MlL-S-23195. fGer.) DIN I .4306; (Ital.) LINI X
AMS 5s I I, 5647: ASME SA3 12, SA403, SA479. SA688; ASThl A276. A3 12, A3 14. A403. A473. A478. A688: FED QQ-S-763. QQ-S-766; hlIL MlL-S-23196; SAE 5405 (3030-t L): 2 CrNi I8 I I. X 3 CrNi I8 I I. X 2 CrNi
18 I I KG. X 2 CrNi 18 1 I KW: (Jap.) JIS SLIS 30-t L. SCS 19; (Swed.) SSt.r2352;(U.K.)B.S.30-tS I2.3O-tS I-t.304S22.S536
Characteristics. Extra low-carbon version of type 304 for restriction of carbide precipitation during melding. Ranks between stabilized and unstabilized grades. because of tendency IO precipitate chromium carbides, Used extensively for welding applications, particularly on parts which cannot be subsequently annealed. Parts are limited to service up to 425 ‘C (795 %). Hardenable by cold mark only. Heat treating limited to: annealing to restore maximum corrosion resistance, softness. and ductility after cold
736 / Heat Treaters Guide \iorking: stress rslieb ing mhen required for stresses occurring from irater quench. when this rapid quench is necessar!,: and on rare occasion. nitriding to imparl thin. hear-resistant surfac?
Forging. after forging
Srart forging at I 1SO to I260 “C t2 IO0 to 3300 “F). Do nor forge stock drops helow 93 “C t 1695 “F,
Recommended Heat Treating Normalizing. Do not normalize Annealing. Anneal at IO IO to I IX “C
Practice
I I850 to 2050 “F). For m&ximum duclility. use a minimum annealinp temperature of 1040°C ( I905 9). Parts can be air cooled from annealing temperature. M’ater quenching not necess;LT\. At 8 IS to -13 “C ( 1500 to 795 V). slo\r cooling can occur for up to 2 h without subsequent danger of suscsptihilit> to intergranular corrosion in natural atmosphenc em ironmsnts. Houe\er. for some applications in the chemical indush, intergranular corrosion uould result from this treatment In aerospace practice. parts are annealed at a bet temperature of 1065 ‘C ( 1950 9) and quenched in water u ith one exception: parts under 2.5 mm (0. IO in.) thick ma! be air cooled or polj mer quenched to minimize distortion. See table for soakin! times. Note: approval of the cognizant engineering organization is required for annealing material in a strain-hardened condition. such as t/j hard; for stress rrlking: or for dimensional stabilization. Heat treating or slow cooling unstabilized grade\ bet\iesn 170 to 8 IS “C (875 to IS00 “F) is prohibited. except for 304L and 3 IhL
Stress
Relieving. Parts can be relieved after quenching to achieve dmiensional stahilitj, by heating IL) 230 to 100 “C (US to 750 %) for up to several hours, depending on section >ix and without change in metnllographic structure. In aerospace practice. part> are stress relieved at 900 ‘C t 1650 ‘?). and quenched in water. As an altematiie. p&arts ma> be stress relked at annealing temperatures. Sectlons under 2.5 mm (0. IO in.) thick may be ;ilr cooled to minimize distortion. Parts fabricated from steel in the strain-hard-
encd condition. such as I!‘? hard, shall not he stress relieved without permission of the cognizant engineering authority. When stress relieving after !
Recommended
Processing
Sequence
Cold moorl; Anneal and cool Stress relieve coptional) Depasskate (if nitriding) Nitride (if required)
304L:
Soaking Times (Aerospace Practice)
Diameter or thickness(a)
Minimum soaking time
of maximum section
Atmosphere
furnace
Salt bath
mm (in.) incluske
min
min
uprL)‘.s0lo loo, oicr 2.somh.3 IO I00l00.301 o\cr 6 25 to 12.50 10.30 to 0.5001
20 25 45
over I I.50 Lo 25.00 10.500 to I 00) a~er25.OOto.~7.5O~I (x)101 SOI
60 7s 90 I OS 120
17 18 35 40 -I5 50 55 60 CC,
over 37 50 10 so.00 1 I .so to ‘.oo t o\er SO.00 IO 62.50 t-7.00 IO ?.50) o\rr62jOlo7500(25010.1.001 o~er7500~3.00~ (a) Thicknes
ii minimum
dimension
(b, of heat irst w-lion
of part or nested load of
pm.
Ibr2IShplujl5nlinfur~\rr! I 2 5mmf0.5 in Jorincremenlof I?.Smm(O.Sin.)over 75 mm,! in.). IL‘) I h. 5 minplus3 min forriery I? 5 mm(O.5 in.)orincremenlof 12.5 i0.S in ro\er75 nun(3 in.1 Source: AhlS17S9/4
736 / Heat Treaters
Guide
s30430 Chemical
Composition. MSI/LINS (~30-130): 0.8 c IMX. XXI htn max. 0.0-H P max. 0.030 S max. I .OO Si max. 8.00 to 10.00 Ni. 17.00 to 19.00 Cr. 3.0-t to 1.0 Cu
Similar
Steels (U.S. and/or
Characteristics. Lower \rork severe cold heading applications
Foreign). hardening
ASTM
A-W? I ~1-7,
rate than type 305. Used for
Forging. Start forging at I IS0 to I26O”C r2 100 to 23OO’~t. Do not forage after forging stock drops beloa Y3 “C ( 1695 “F~. Cool to black color m less than 3 min. using liquid quench if necessary
Recommended Normalizing.
Heat Treating
Practice
Do not nomtalize
Annealing. Anneal at 1010 to I I70 “C i I850 to ZOSO ?F,. For maximum ductilit 1 and softness. use a minimum annealing temperature of lo-10 “C I 1305 JF t. To guard against distortion of thin. delicate parts. Iea\e ample room for expansion bet\ieen parts. Stainless grades espand about twice as much as carbon and low-alloy steels. Allou enough time for through heating after thermocouple has reached temperature. Stainless grades habe approximately half the themlal conductit it) of carbon and lo\< -alloy steels. Choice of atmosphere depends on finish desired and whether surface stock will be removed. For bright annealing. use vacuum or an atmosphere of hydro en or dissociated ammonia at de\\ point of -62 to -7-t ‘C (-80 to -100 4 ). Parts must be thoroughly clean and dry. Inert sases argon and helium (although expensive) and nitrogen. u ith dew points of less than -5-l
“C t-6S Tt. can be used. They lath the reducing etfect of hydrogen. so slipht discoloratton m the form of chrome oxide can result, Salt, exothermic. or sndothemtic atmospheres are satisfactory for nonbright annealing. Salt is difficult to remove. and rinse quenching at SYS “C (I IO5 “F, is not recommended. because interrupted quench at elevated temperature cannot be tolerated. Exothermic and endothemlic atmospheres must be carefully controlled at equivalent carbon potential to avoid carburization. which will seriously loiter corrosion resistance. Same problem mith atmosphere annealing. If oxtdizing conditions are present. scale will form. Difficult to remo\e in subsequent descaling operations. Cool rapidly from annealing temperature: no more than 3 min to black color. Section size detemmines quenching medium: water for heavy sections. air blast for intemtediate sizes. and still air for thin secttons. Carbides can precipitate at erain boundaries when parts are cooled too slowly betueen -t2S to YOOL“C t 795 to I650 ‘?3. In aerospace practice. parts are annealed at a set temperature of 1065 *C I IYSO ‘FJ and quenched in \\aater with one exception: parts under 2.5 mm to.10 in.) thick may be air cooled or polymer quenched to minimize distortion. See table for soaking times. Note: approval of the cognizant engineering orgamzarton is requtred for annealing material in a strain-hardened condition. such as ‘Q hard; for stress relieving; or for dimensional stabilization, Heat treating or slo\\ cooling unstabilized grades between -I70 to 8 IS “C (875 to IS00 %j is prohibited, except for 3ML and 3 l6L
Stress Relieving. dimensional
stability.
can be relieved after quenching to achieve Pm by heating to 230 to -IO0 ‘C t-l35 to 750 ?) for up to
Austenitic
Stainless
Steels / 737
several hours. depending on section size and without change in metallographic structure. In aerospace practice. parts are stress relieved at 900 “C ( 1650 %). and quenched in water. As an alternative. parts may be stress relieved at annealing temperatures. Sections under 7.5 mm (0. IO in.) thick may be air cooled to minimize distortion. Parts fabricated from steel in the strain hardened condition. such as I/? hard. shall not be stress relieved uithout permission of the cognizant engineering authority. Whsn stress relic\ ing after welding, hold for 30 min minimum at the stress relies ing temperature. Heat treating or slow cooling of unstabilized grades between 470 to 815 “C (X75 to IS00 @F) is prohibited. except for 304L and 316L. See table for soaking times
to IO00 HK. Case will rapidly drop to 200 HK core hardness, at approximately 0. I65 mm (0.006S in. )
Nitriding. Not recommended. Case seriousI> impairs corrosion resistance in most media. Case seldom more than 0.127 mm (0.005 in.) deep. Only used in specialized applications where material mubt be nonmagnetic and have wear-resistant surface. If nitrided. parts must be in annealed condition to prevent flaking or blistering of nitrided case. All sharp comers should be replaced m ith radii of not less than I .SY mm (0.06 in.). Film of pnmtily chromium oxide. that protects stainless allo! s from oxidation and corrosion. must be removed prior to nitriding. Accomplished by \\et blasting, pickling. chemical reduction in reducing atmosphere. submersion in molten salt. or by one of several proprietar) processes. If doubt exists that complete and uniform depassivation has occurred. further reduction of the oxide may be accomplished in furnace by means of reducing hydrogen atmosphere or suitable proprietar) agent. After depassivation. avoid contamination of surface bv finger or hand marking. Single-stage nitriding adequate at 575 to 550 “C (975 to 1010 ‘%) for 20 to 18 h (depending on case depth required,. Dissociation rates for single-stage c>;cle are from 20 to 35%. Hardness is as high as 1000 to 1350 HK on surtace. 18-h cycle produces case extending to 0. I27 mm to.005 in. t with approximatel) 800
S30430:
Recommended
Processing
Cold work Anneal and quench Remove surface contamination Stress relieve Depassi\ate (if nitriding) Nitride iif required)
Soaking
Sequence
(if required)
Times (Aerospace
Diameter or thickness(a) nfmatimum section mm (in.) inclusive
mer 2.50 ~~6.3 ~0.100 toU.Xb over 6 25 lo 12.50 (0.250 IO 0.5001 01s~ I I.50 to 25 00 (0.500 to I .OO) o\er ?5.(JO10 37.50( I .OOto 1.5Oj o\er 3750 to 5O.OOt I SO102 001 o\cr5000~o62.SOr2.0(1to2.~0) o\er6~.50to71i.00t2.SOto 3 00, o\er7s OOf3 00,
Practice)
hlinimum Atmosphere furnace min 20 ‘5 -15
60 75 90 IO5 I10 ib,
soaking
time Salt bath min
17 I8 35 10 4s so 55 60 (Cb
~a) Thickness 15minimum dlmrnsion of hea! lest section of part or nested load of parts. tbj2.35 hplus ISmin forever) Il.5 mm(O.5 in.,orincrementof 12.Snun(O.S in.)over 7.5mm13 in j.(c) I h. 5 minplus5 min foretey I2 5 nunt0.S in.)orincremrntof 12.5 t0.S in 1over 75 mm I3 in.) Source, 4hlS 27S9U
Austenitis
Steels / 737
304LN Chemical
Composition.
AISI/UNS
(S30453):
O.O? C.
X0
hln.
0.045 P, 0.03 S. I .OO Si. 8.0 to 17.0 Ni. 18.0 to X.1) Cr. 0. IO to 0.16 N
Recommended Annealing.
Heat Treating
Practice
parts are annealed at a set temperature of 1065 “C (19.50 “F) and quenched in water u,ith one exception: Parts under 7.S mm (0.10 in.) thick ma) he air cooled or polymer quenched to minimize distortion. See table for soaking times. Note: approval of the cognizant engineering organization is required for annealing material in a strain-hardened condition. such as bj hard: fbr stress rclkvinp: or for dimensional stabilization. Heat treating or slou cooling unstahilizcd grades between 370 to 8 IS “C (875 to IS00 “F) is prohibited. except for M-IL and 316L In aerospace
-170 to 8 I5 ‘C 1875 to I500 “F) is prohihitcd, Se2 table for sonKing times
304LN:
Soaking
Times (Aerospace
except for 304L and 3 l6L.
Practice)
practice.
StrSSS Relieving. Ln aerospace practice. parts are stress relked at 900 “C (1650 9). and quenched in eater. As an ahematite. parts ma\ he stress relieved at annealing temperatures. Sections under 2.5 mm (0. Idin.) thick may be air cooled to minimize distortion. Parts fabricated from steel in the strain-hardened condition. such as % hard. shall not he stress relieved without permission of the cognizant e@ineeting authority. When stress relieving after welding. hold for 30 min minimum at the stress relies ing temperature. Heat treating or slow cooling of unstabilized -grades het\\een
Diameter or thickness(a) of maximum section mm (in.) inclusive up to 2 solo.loo, o\~r2..5Oto6.‘5ttJ.l001oO2ri01 oter 6.25 to 12.50 (0.250 to 0.500) over 1250 to 25.00 10.500 to I .OO) 01 er 25 00 to 37 SO I I 00 to I .5(J) o\er 37.50 to SO OOt I SO to 2 00, o\ cr 50.00 to 6, 50 t2.00 IO 2.50, o\cr6~.50to7tr.(X)1~..‘10to 3 00) o\rr75OOt?OO1
Minimum Atmosphere furnace min 20 25 45 60 75 90 IO5 I70 tb,
soaking
time Salt bath min 17 18 35 10 1s so 55 60 (21
I~I Thickncs IS minimum dimcnGon of hru\ irst sxtion of part or nested load of parts tbrZ.3hplusl5mmiore\q I3mmt0..‘,in.~orinsrementof13nmi10..5in.)over 7Smmt!m.L~s~Ih.Sminplus5niinforr~e~ 1~.5mmt0.5in.~orincrementof17.5 10.5 tn 1o\rr75 mm,3 in I Source. AhlS 2759/-l
304N Chemical
Composition.
AlSl/UNS
(S30451):
0.08
C nl;Lx.
2.00
hln max, 0.045 P max. 0.030 S max. I .OO Si max. 8.00 to 1050 Ni. 18.00 1o20.OOCr.O.IOto0.l6N
Similar Steels (U.S. and/or Foreign). ASME SA 182. SA2 13. SA2-40, SA249, SA312. SA358. SA376. SA130. SA479: ASTM Al82 A2 13. AXO. A249. A3 I’. A358. A376. A-tO3. A-130. A479 Characteristics.
Contains added nitrogen to increase strength with minimum effect on ductility and corrosion resistance. Type 304N is nonmagnetic when annealed. More resistant to increased magnetic pemteability on cold working than type 30-l
Forging. Start forging at I IS0 to 126O’C (2 100 to 23000Fj. Do not forge after forging stock drops below 925 “C ( 1695 %). Cool to black color %I less than 3 min. using liquid quench if necessary
Recommended Normalizing.
Heat Treating
Practice
Do not normalize
Annealing. Anneal at IO IO IO I I20 “C ( I850 to 2050 ‘vj. For maximum ductility and softness. use minimum annealing temperature of 1040 ‘C (I905 ‘%). To guard against distortion of thin, delicate parts, leave ample room for expansion between parts. Stninless grades expand about twice as much as carbon and low-alloy steels. Allow enough time for through heating after thermocouple has reached temperature. Stainless grades have approximately half the thermal conductivity of carbon and low-alloy steels. Choice of atmosphere depends on finish desired and whether surface stock will be removed. For bright annealing. use vacuum or an atmosphere of hydra en or dissociated ammonia at dew point of -62 to -7-l “C (-80 to -100 4 j. Parts must be thoroughly clean and dry. inert gases argon and helium (although expensive) and nitrogen. with dew points of less than -5-l “C (-65 9). can be used. They lack the reducing effect of hydrogen. so slight discoloration in the foml of chrome oxide can result. Sah, exothermic. or endothemuc atmospheres are satisfactory for nonbright annealing. Salt is difftcult to remove. and rinse quenching at 595 ‘C ( I IO5 “n is not recommended. because interrupted quench at elevated temperature cannot be tolerated. Exothermic and endothemuc atmospheres must be carefully controlled at equivalent carbon potential to avoid carburizatton. which will seriously lower corrosion resistance. Same problem with atmosphere annealing. If oxidizing conditions are present. scale will fomt. Difftcult to remove in subsequent descaling operations. Cool rapidly from annealing temperature: no more than 3 min IO black color. Section size detemines quenching medium: water for heavy sections. air blast for intermediate sizes, and still air for thin sections. Carbides can precipitate at grain boundaries u hen parts are cooled too slowly between 125 to 900 “C (795 IO 1650 TJ. In aerospace practice. parts are annealed at a set temperature of 1065 “C t 1950 “Fj and quenched in water with one exception: parts under 2.5 mm (0. IO in.) thick may be air cooled or polymer quenched to minimize distortion. See table for soaking times. Note: approval of the cognizant engineering organization is required for annealing material in a strain-hardened condition. such as !$ hard: for stress relieving: or for dimensional stabilization. Heat treating or slow cooling unstabilized grades between 170 to 8 IS ‘C (875 to IS00 “Fj is prohibncd. except for 304L and 3 l6L Stress Relieving. Parts can be relieved after quenching to achieve dimensional stability. by heating to 230 to 400 “C (US to 7SO % for up to several hours. depending on section stze and without change m mettalloprnphic structure. In aerospace practice. parts are stress relieved at 900 “C ( I650 @F). and quenched in water. As an alternative. parts may be stress relieved at
annealing temperatures. Sections under 2.5 mm (0. IO in.) thick may be air cooled to minimize distortion. Parts fabricated from steel in the strain-hardened condition. such as I/;, hard. shall not be sttess relieved without permission of the cognizant engineering authority. When stress relieving after welding. hold for 30 mitt minimum at the stress relieving temperature. Heat treating or slow cooling of unstabilized grades between 470 IO 815 “C (875 to IS00 %j is prohibited. except for 304L and 3 I6L. See table for soaking times
Nitriding. Not recommended. Case seriously impairs corrosion resistance in most media. Case seldom more than 0. I27 mm (0.005 in.) deep. Only used in specialized applications where material must be nonmagnetic and have wear-resistant surface. If nitrided, parts must be in annealed condition to prevent flaking or blistering of nitrided case. AU sharpcomers should be replaced with radii of not less than I.59 mm (0.06 in.). Film of primarily chromium oxide. that protects stainless alloys from oxidation and corrosion. must be removed prior to nitriding. Accomplished by wet blastmg, pickling. chemical reduction in reducing atmosphere. submersion in molten salt. or by one of several proprietary processes. If doubt exists that complete and uniform depassivation has occurred. further reduction of the oxide may be accomplished in furnace by means of reducing hydrogen atmosphere or suitable proprietary agent. After depassivation, avoid contamination of surface bv finger or hand marking. Single-stage nitriding adequate at 52.5 IO 550 *C (975 to 1020 ?j for 20 to 18 h (depending on case depth required). Dissociation rates for single-stage cycle are from 20 to 35%. Hardness is as high as 1000 to 1350 HK on surface. 48-h cycle produces case extending to 0. I27 mm (0.005 in.) with approximately 800 to 1000 HK. Case will rapidly drop to 200 HK core hardness. at approximately 0. I65 mm (0.0065 in. j
Recommended
Processing
Cold work AMeal and quench Remove surface contamination Stress relieve Depasstvate (if nitridingj Nitride (if required,
304N:
Soaking
50roh.3tO
colo62.so~2
l00l00.301
0010
Practice)
Minimum Atmosphere furnace mio
over 6.25 IO 12.50 (0.250 to 0.500) over 12.50 IO 25.00 (0.500 LO 1.001 o\er 2s.00 IO 37.90 ( I al IO I.50, o~rr37.5010 jO.OOt I .5010XO~ over50
(if required)
Times (Aerospace
Diameter or thickness(a) of masimum section mm (in.) inclusive
o\er2
Sequence
2.50)
o\erh?.SO IO 75.00 I 2 SO IO 3.00, "\rr7s.oo~3.ool
20 25 -Is 60 7s 90 I OS I20 (b)
soaking
time Salt batb mio I7 18 35 40 45 SO 5s 60 CC)
tajThicl\ness is minilnumdimcnsionofhra\ic~tsestionofp~ornested toadofparts. Ibj? 15 hplus l~nunfore~cry l~.SrnmtO.Zin jorincremenrof 12.5mm(0.5in.)ober 75 nun (3 in I. (sr I h , 5 min plus 5 min for e\er) I2.S mm (0.5 in.)or increment to.5 in Joker 75 mm (3 In.). Source. .AhlS 2759/J
of 11.5
Austenitic
Stainless
Steels I739
305 Chemical Mnmax.0.045 to 19.00 Cr
Composition.
AISI/UNS (S30500): 0.12 C max. 2.00
Pmax.0.030Smax.
l.OOSi max. 10.50 to 13.OONi. 17.00
Similar
Steels (U.S. and/or Foreign). AMS 5s 11, 5685. 5686: ASME SA 193. SAl94. SA240; ASTM A 167. A240. A2-19. A276. A3 13. A314, A368. A-l73. A478. A493, A51 I, A554 A580; FED QQ-S-763. QQ-W-423; SAE J-MIS (30305); (Ger.) DIN 1.4303; (Ital.) UNI X 8 CrNi I9 IO: (Jap.) JIS SUS 305. SDS Jl Characteristics. This austenitic chromium-nickel steel has lower rate of work hardening than types 302 and 304. Less change of magnetic permeability. Used for spinning, special drawing, and cold heading applications Forging. Start forging at I I50 to I260 “C (2 100 to 2300 9). Do not forge after forging stock drops below 925 ‘C ( 1695 “n. Cool to black color in less than 3 mm. using liquid quench if necessary
Recommended Normalizing.
Heat Treating
Practice
Do not normalize
Annealing.
AMed at 1010 to I I20 “C ( I850 to 2050 OF). For maximum ductili and softness. use a minimum annealing temperature of 1010 ‘C (1905 % To guard against distortion of thin, delicate parts, leave ample room for expansion between parts. Stainless grades expand about twice as much as carbon and low-alloy steels. Allow enough time for through heating after thermocouple has reached temperature. Stainless grades have approximately half the thermal conductivity of carbon and low-alloy steels. Choice of atmosphere depends on finish desired and whether surface stock will be removed. For bright annealing. use vacuum or an atmosphere of hydro en or dissociated ammoma at dew point of -62 to -74 ‘C (-80 to -100 %R Parts must be thoroughly clean and dry. Inert gases argon and helium (although expensive) and nitrogen. with dew points of less than -54 ‘C (-65 ‘%). can be used. They lack the reducing effect of hydrogen. so slight discoloration in the form of chrome oxide can result. Salt. exothermic. or endothermic atmospheres are satisfactory for nonbright annealing. Salt is difficult to remove. and rinse quenching at 595 “C (I I05 %) is not recommended, because interrupted quench at elevated temperature cannot be tolerated. Exotherrnic and endothermic atmospheres must be carefully controlled at equivalent carbon potential to avoid carburization. which will seriously lower corrosion resistance. Same problem with atmosphere annealing. If oxidizing conditions are present. scale will form Difftcult to remove in subsequent descaling operations. Cool rapidly from annealing temperature: no more than 3 mm to black color. Section size determines quenching medium: water for heavy sections. air blast for intermediate sizes. and still air for thin sections. Carbides can precipitate at grain boundaries when parts are cooled too slowly between 425 to 900 ‘C (795 to 1650 %). In aerospace practice, parts are annealed at a set temperature of 1065 “C ( 1950 ?r) and quenched in water with one exception: parts under 2.5 mm (0. IO in.) thick may be air cooled or polymer quenched to minimize distortion. See table for soaking times. Note: approval of the cognizant engineering organization is required for annealing material in a strain-hardened condition, such as t/d hard: for stress relieving; or for dimensional stabilization. Heat treating or slow cooling unstabilized grades between 470 to 8 I5 “C (875 to 1500 “F, is prohibited. except for 304L and 3 I6L
Stress Relk?ViIlg. Parts can be relieved after quenching to achieve dimensional stability, by heating to 230 to -400 ‘C (US to 750 ‘%>F)for up to severaJ hours, depending on section size and without change in metallographic StrucNre.
In aerospace practice. parts are stress relieved at 900 ‘C (1650 %). and quenched in water. As an alternative. parts may be stress relieved at annealing temperatures. Sections under 2.5 mm (0. IO in.) thick may be air cooled to minimize distortion. Parts fabricated from steel in the strain-hardened condition. such as t/z hard. shall not be stress relieved without pemlission of the cognizant engineering authority. When stress relieving after welding. hold for 30 min mtninumi at the stress relieving temperaNre. Heat treating or slow cooling of unstabilized grades between 470 to 8 I5 “C (875 to IS00 OF) is prohibited. except for 301L and 316L. See table for soaking limes
Nitriding. Not recommended. Case seriously impairs corrosion resistance in most media. Case seldom more than 0. I27 mm (0.005 in.) deep. Only used in specialized applications where material must be nonmagnetic and have wear-resistant surface. If nitrided, parts must be in annealed condition to prevent flaking or blistering of nitrided case. All sharp comers should be replaced with radii of not less than I .59 mm (0.06 in.). Film of primarily chromium oxide. that protects stainless alloys from oxidation and corrosion. must be removed prior to nitriding. Accomplished by wet blasting. pickling. chemical reduction in reducing atmosphere, submersion in molten salt. or by one of several proprietary processes. If doubt exists that complete and umform depassb ation has occurred. further reduction of the oxide may be accomplished in furnace by means of reducing hydrogen atmosphere or suitable proprietary agent. After depassivation. avoid contamination of surface b2 finger or hand marking. Single-stage nitriding adequate at 525 to 550 C (975 to 1020 9) for 20 to 48 h (depending on case depth required). Dissociation rates for single-stage cycle are from 20 to 35%. Hardness is as high as 1000 to 1350 HK on surface. 48-h cycle produces case extending to 0. I37 mm (0.005 in.) with approximately 800 to 1000 HK. Case will rapidly drop to 200 HR core hardness. at approximately 0. I65 mm (0.0065 in.)
Recommended
Processing
Cold work Anneal and quench Remove surface contamination Stress relieve Depassivate (if nitriding) Nitride (if required)
305:
Soaking
Sequence
(if required)
Times (Aerospace
Diameter or thickness(a) of maximum section mm (in.) inclusive up to 2.SOtO 100) over2.50t06.lS(0.100to02501 over 6.25 to 11.50 (0.250 to O.SOO] over 12.50 to 25.00 tO.SOO to 1.00) over 2S.00 to 37.SO t 1.OO to 1.I%J over 37.SO to SO.00 t l .SO 10 2.001 over SO.00 to61.SOi2.00 to I! 501 o\er61.50 to 7S.OOt2 SO to 3.OOt ovcr75.00t3.00~
Practice)
Minimum soaking time Atmosphere furnace Salt bath min min IO 15 15 60 7s 90 105 120 (b)
17 18 3s 40 45 SO 55 60 ICj
(a) Thickness is mimmum dimension of hca\;iest section of part or nested load of parts. tbi 2 2S h pIus IS min forebey 12.5 mm (0.5 in )or increment of 12.5 mm(0.S in.)over 7Stnmt3 in.). ICI I h. 5 minplus5 mm foretery 12.5 mmt0.5 in.)orincrementof 12.5 10.5 in.)o\er 75 mm (3 in.). Source: AhIS 275914
740 / Heat Treaters
Guide
305: Microstructure. Electrolytic: 50% phosphoric acid, 1000x. Creep-rupture specimen. Annealed at 1120 “C (2050 OF), 92 h. Tested at 650 “C (1200 “F), 371 h. Carbon migration and precipitation of chromium carbide (Cr&) at austenite grain boundaries.
740 / Heat Treaters
Guide
308 Chemical
Composition.
0.045 P.O.03OS.
Similar
l.OOSi.
AIsI/UNS (S30800): 0.08 C. 2.00 hln.
lO.Oto
Steels (U.S. and/or
I?.ONi.
19.00to~1.00Cr
Foreign).
A314 A473. AS80: SAJZ JWS (30308~: Ger.) CrNi 19 IO: IJap.) JIS SLlS 305. SllS 305 J I
ASTM ~167. ~276. DlN 1.4303: (TtaJ.) CrNl X 8
Characteristics.
Corrosion and heat resistance superior to t!pe 30-l. lked for welding hire. Nonmagnetic when annealed. Slightly magnetic when cold worked
Forging. Start forging at I IS0 to 1260°C (2 100 to 2300°F~. Do not forge after forging stock drops below 975 “C t 1695 ‘?). Cool to black color in less than 3 min. using liquid quench if necess?
Recommended Normalizing.
Heat Treating
Practice
Do not normalize
Annealing. Anneal at 1010 to I I20 “C t I850 to 2050 ?). For maximum ductilitb and softness. use a minimum annealing temperature of IWO “C (190s %). To guard agamst distortion of thin, delicate parts. lea\e ample room for expansion between parts. Stainless grades espand about twice as much as carbon and low-alloy steels. Alloy enough time for through heating after thermocouple has reached temperature. Stainless grades have approximately half the thermal conductivit> of carbon and low-allo> steels. Choice of atmosphere depends on finish desired and whether surface stock will be removed. For bright annealing. use vacuum or an atmosphere of hydra en or dissociated ammonia at de\\ point of -62 to -74 “C t-80 to -100 4 ). Parts must be thoroughI> clean and dq. Inert gases argon and helium (although expensive) and nitrogen. u ith dew points of less than -5-l “C t-65 ?F). can be used. The) lack. the reducing effect of hydrogen. so slight discoloration m the form of chrome oxide can result. Salt. exothsrnlic. or endothermic atmospheres are satisfactory for nonbright annealing. Salt is diflicult to remove. and rinse quenching at 595 ‘C ( I IO5 9) ih not recommended. because interrupted quench at elevated temperature cannot be tolerated. Exothermic and endothermic atmospheres must be carefull) controlled at equivalent carbon potential to avoid carburizatlon. which nil1 seriously lower corrosion resistance. Same problem u ith atmosphere annealing. If oxidizing conditions are present. scale will form. Difficult to remove in subsequent descaling operations. Cool rapidI> from annealing temperature: no more than 3 min to black color. Section size detemlines quenching medium: water for heav! sec-
tions. air blast for intermediate sizes. and still air for thin sections. Carbides can precipitate at grain boundaries &hen parts are cooled too slowly between 425 to 900LoC (795 to 1650 “F). In aerospace practice, parts are annealed at a set temperature of 1065 “C t 1950 ‘>FJ and quenched in Uater with one exception: parts under 2.5 mm (0. IO in.) thick may be air cooled or polymer quenched to minimize distortion. See table for soaking times. Note: approval of the cognizant engineering organization is required for annealing material in a strain-hardened condition. such as I/, hard: for stress relieving; or for dimensional stabilization. Heat treating or slow cooling unstabilized grades between 470 to 8 IS ‘C 1875 to I SO0 9) is prohibited. except for 304L and 3 l6L Stress RelieVing. Parts can be relieved after quenching to achieve dimensional stability. b> heating to 230 to 400 “C (US to 750 ‘%) for up to several hours. depending on section size and without change in metallographic structure. In aerospace practice, parts are stress relic\ ed at 900 “C ( I6SO %), and quenched in Water. As an alternative, parts may be stress relieved at annealing temperatures. Sections under 2.5 mm (0. IO in.) thick may be air cooled to minimize distortion. Parts fabricated from steel in the strain-hardened condition. such as t/z hard. shall not be stress relieved without permission of the cognizant engineering authority. When stress relieving after welding, hold for 30 min minimum at the stress relieving temperature. Heat treating or slo\\ cooling of unstabilized grades between 170 to 815 “C (875 to IS00 ?) is prohibited. escept for 304L and 316L. See table for soaking times
Nitriding. Not recommended. Case seriously impairs corrosion resistance in most media. Case seldom more than 0. I27 mm (0.005 in.) deep. Only used in specialized applications H here material must be nonmagnetic and ha\e wear-resistant surface. If nitrided. parts must be in annealed condition to prevent flaking or blistering of nitrided case. All sharp comers should be replaced n ith radii of not less than I .S9 mm (0.06 in.). Film of primaril) chromium oside. that protects stainless alloys from oxidation and corrosion. must be removed prior to nitridinp. Accomplished by wet blasting. pickling. chemical reduction in reducing atmosphere. submersion in molten salt. or b! -one of several proprietary processes. If doubt exists that complete and umk~rm depassi\ation has occurred. further reduction of the oxide may be accomplished in furnace by means of reducing hydrogen atmosphere or suitable propriety agent. After depassivation. avoid contamination of 3urface bj finger or hand marking. Single-stage nitriding adequate at 525 to 550 “C 1975 to 1020 OF) for 10 to -48 h (depending on
Austenitic
case depth required). Dissociation rates for single-stage cycle are from 20 to 35%. Hardness is as high as 1000 to 1350 HK on surface. 18-h cycle produces case extending to 0. I27 mm (0.005 in. t with approstmatel! 800 to 1000 HK. Case will rapidly drop to 200 HK core hardness. at approximately 0. I65 mm tO.0065 in.)
Recommended
Processing
Cold hark Anneal and quench Remove surface contamination Stress relieve Depassibate (if nitriding) Nitride (if required)
Sequence
t if required)
308:
Soaking
Times (Aerospace
Diameter or thickness(a) of maximum section mm (in.) inclusive up tll2.50t0.1001 o\er2.S0to6’StO.lM3to(J.75[1) over 6.25 to 12.50 (0.250 to 0.5001 over I2 50 to 25.00 10 500 to I.001 ovrr7S.00 to 37.SOt I CO to 1.50’1 o~~r37.50to50.00t1.50t~~.~i 1~ er SO.00 to 62 SO I 2.00 to 2.SO) 0~er6~.90to75.00t2.9(1t03.00) o\er7S.tMt?.OO)
Stainless
Steels / 741
Practice)
Minimum soaking time Atmosphere furnace Salt bath min min ‘0 25 -1s 60 7S 90 IO5 120 tb)
17 18 35 -IO 15 50 55 60 (c)
(a) Thickness is minimum dimension of hea\ iest section ofpart or nested load of parts. lb) 2.3 hplus IS min foreveq 12.5 mm to.5 in.~orincrementof 12.5 mm(0.S in.)over 75 mm t3 in.). (5) I h. 5 mm plus 5 min forever! I33 mm (0.5 in.)orincrement of 12.5 10.5 in.) o\er 75 mm t 3 in.). Source. AhlS 2759/-l
Austenitic
Stainless
Steels / 741
309 Chemical Composition. AISIjUNS (S3OWO): 0.20 C. XXI 0.045 P. 0.030 S. 1.00 Si max. 13.0 to IS.0 Ni. 2.0 10 Z-l.0 Cr
hln.
Similar
Steels (U.S. and/or Foreign). AWE .%X9. SA3 12. SA358. SAA03. SA-IO9; ASThl A167, A319. A776. 4312, A31-1. A358. A-lO3. AJ09. AA73. AS I I. ASS-I, AS80: FED QQ-S-763. QQ-S-766: MfL SPEC MfL-S-867: SAE J-IO5 (30309); (Ger.) DIN 1.4828; (Ital.) IJNI X I6 CrNi 23 I-l Characteristics.
High heal resisting
qualities.
Used for welding
wire
applications
Forging.
Start forging at I IS0 to I230 “C (2 100 to 32-15 OF). Finish forging at 980 LO 1010 ‘C ( I795 to I850 ‘T). Cool to black color in less than 3 min. using liquid quench if necess+
Recommended Normalizing.
Heat Treating
Practice
Do not normalize
Annealing. AMeti at 1030 to I I20 ‘C ( 1905 to 2050 %). To guard against distortion of thin. delicate parts. Iea\e ample room for expansion between parts. Stainless grades expand about IW ice as much as carbon and low-alloy steels. Allow enough time for through heating afterthermocouple has reached temperature Stainless grades have appro\imnrel) half the thermal conductivity of carbon and low-alloy steels. Choice of amiosphere depends on finish desired and whether surf&e stock will be remoled. For bright annealing use vacuum or an atmosphere of hydrogen or dissociated ammonia at dew point of -62 to -7-l “C i-80 to -100 %I. Parts must be thoroughly clean and dry. Inert gases argon and helium (although expensive) and nitrogen. with dew points of less than -53 “C C-65 @F). can be used. They lack the reducing effect of hydrogen. so slight discoloration in the form of chrome oxide can result. Salt. exothermic. or endothemtic atmospheres are satisfactory for nonbright annealing. Salt IS difficult to remobe, and rinse quenching at 595 “C (I IO5 c”F) is not recommended. because interrupted quench at elevated temperature cannot be tolerated. Exolhermic and endothermic atmospheres must be carefully controlled at equivalent carbon potential to avoid carburizarion. which will seriously lower corrosion resistance. Same problem with amiosphere annealing. If oxidizing conditions are present. scale will form. Difficult to remove in subsequent descaling operations. Cool rapidly from annealing temperature: no more than 3 min to black color. Section size determines quenching medium: enter for heavy sections. air blast for intermediate sizes. and still air for thin sections. Carbides
can precipitate a~ grain boundaries when parts are cooled too slowly between 25 to 900 ‘C (795 to I650 9). In aerospace practice. parts are annealed at a se1 temperature of 1065 “C ( 19.50 % and quenched in \\ater \< ith one exception: parts under 2.5 mm (0. IO in.) thick may be air cooled or polymer quenched to minimize distortion. See table for soaking times. Note: approval of the cognizant engineenng organization is required for annealing material in a strain-hardened condition. such as ‘14 hard: for stress relieving; or for dimensional stabilization. Heat treating or slow cooling unstabilized grades between 470 IO 815 ‘C (875 IO IS00 %‘I is prohibited. except for 303Land 316L Stress RelieVing. Parts can be relieved after quenching 10 achieve dimensional stability, bb heating IO 230 to -IO0 ‘C (US 10 750 %) for up to several hours. depending on section size and without change in metallographic structure. In aerospace practice. parts are stress relicvsd at 900 ‘C ( 1650?). and quenched in Mater. As an alternative. parts may be stress relieved at annealing temperatures. Sections under 1.5 mm (0. IO in.) thick may be air cooled to mininlize distortion. Parts fabricated from steel in the strain-hardened condition. such as !/2 hard. shall not be stress relieved without permission of the cognizant engineering authority. When stress relieving after welding. hold for 30 min minimum al the stress relieving temperature. Hear treating or slow coolin! of unstabilized grades between 470 to 815 ‘C (875 IO 1500 OF) is prohiblted. ehcepr for JO-IL and 316L. See table for soakins times
Nitriding. Not recommended. Case seriously impairs corrosion resistance in most media. Case seldom more than 0. I27 mm (0.005 in.) deep. OnI! used in specialized applications where material must be nonmagnetic and have wear-resistant surface. If nitrided. parts must be in annealed condition 10 prevent flaking or blistenng of nitrided case. All sharp comers should be replaced with radii of not less than I .59 mm (0.06 in.). Film of prim‘arily chromium oside. that protscl\ slainless alloys from oxidation and corrosion. must be removed prior 10 nitriding. Accomplished by wet blasting. pickling. chemical reduction in reducing atmosphere. submersion in mohen salt. or bt one of heveral proprietary processes. If doubt exists that complete and umform depassi\ ation has occurred. further reduction of the oxide ma] be accomplished in furnace by means of reducing hydrogen atmosphere or suitable propriclnq agent. After depassivalion. avoid cont,anination of surface by finger or hand marking. Single-stage niuiding adequate at 525 IO 550 “C (975 IO 107-O ?=) for 30 to -IX h (depending on case depth required,. Dis\ocistion rates for single-s&e cycle are from 20 to 3.55. Hardness is as high as 1000 to 1350 HK on surface. 48-h cycle
742 / Heat Treaters
Guide
produces case extending to 0.127 mm (0.005 in.) with approximately 800 to 1000 HK. Case will rapidly drop to 200 HK core hardness. at approximately 0. I65 mm (0.0065 in.)
Recommended l l l l l l
Processing
Cold work Anneal and quench Remove surface contamination Stress relieve Depassivate (if nitriding) Nitride (if required)
Sequence
(if required)
309:
Soaking
Times (Aerospace
Diameter or thickness(a) of maximum 5ection mm (in.) inclusive upt02.50(0.100) oter 2.SOto6.2S~0.lOOto0.25Oj over 6.25 to 12.50 (0.150 to 0.500) 015r 12 50 to 25 00 IO.500 ~0 I.001 owr 25.00 to 37.50 ( I.00 to I SO) ow 37.50 to 50.00 ( I .SO to 2.00) over 50.00 to 62.50 (2.00 to 250) over62.50to75.00(2.50to3.00) over 75.00(3.00) (a) Thickness (b)2.2Shplus 75 mrn(3 in.) (0.5 in.)over
Practice)
Minimum soaking time Atmosphere furnace Salt bath min min 20 25 15 60 75 90 105 130 (b)
17 18 35 40 45 50 55 60 (d
is minimum dimension of hea\ iest section of part or nested load of parts. ISminfore\ery 12.5mm(0.5in.)orincrementof 12.5mm(O.Sin.)over (5) I h, 5 min plus5 min forevery 12.S rnm(O.5 in.)orincrementof 12.5 75 mm (3 in.) Source: AhlS 275914
742 / Heat Treaters
Guide
309s Chemical COmpOSitiOn. AISIjUNS (S30908): 0.08 C. X0 0.045 P. 0.030 S. 1.00 Si. 12.00 to 15.00 Ni. 22.00 to 24.00 Cr
Mn.
Similar
Steels (U.S. and/or Foreign). AMS 5523. 5573. 5650: ASME SA240; ASTM A 167. A240. A276, A3 I-1. A51 I, A554. A580; SAE J405 (30309 S); (Ger.) DfN 1.4833; (Fr.) AFNOR Z IS CN 21.13; (Ital.) UNI X 6 CrNi 23 I4 Characteristics.
High heat resisting
qualities.
Used for welding
wire
applications
Forging. Start forging at I I20 to 1230 ‘C (2050 to 2245 ‘%). Finish forging at 980 to 1010 ‘C ( 1795 to I850 ‘%). Cool to black color in less than 3 min. using liquid quench if necessary
Recommended Normalizing.
Heat Treating
Practice
DOnot normalize
Annealing. Anneal at 1040 to I I20 “C ( 1905 to 2050 @F). To guard against distortion of thin. delicate parts. leave ample room for expansion between parts. Stainless grades expand about twice as much as carbon and low-alloy steels. Allow enough time for through heating after thermocouple has reached temperature. Stainless grades have approximately half the thermal conductivity of carbon and low-alloy steels. Choice of atmosphere depends on finish desired and whether surface stock will be removed. For bright annealing, use vacuum or an atmosphere of hydrogen or dissociated ammonia at dew point of -62 to -74 ‘C (-80 to -100 OF). Parts must be thoroughly clean and dry. Lnert gases argon and helium (although expensive) and nitrogen. with dew points of less than -5-l ‘C (-65 OF). can be used. They lack the reducing effect of hydrogen. so slight discoloration in the form of chrome oxide can result. Salt. exothermic. or endothermic atmospheres are satisfactory for nonbright annealing. Salt is difticult to remove. and rinse quenching at 595 ‘C (I I05 OF) is not recommended. because interrupted quench at elevated temperature cannot be tolerated. Exothermic and endothermic atmospheres must be carefully controlled at equivalent carbon potential to avoid carburization, which will seriously lower corrosion resistance. Same problem with atmosphere annealing. If oxidizing conditions are present. scale will form. Difficult to remove in subsequent descaling operations. Cool rapidly from annealing temperature: no more than 3 min to blach color. Section size determines quenching medium: water for heavy sections. air blast for intermediate sizes. and still air for thin secttons. Carbides
can precipitate at grain boundaries when parts are cooled too slowly between -125 to 900 “C (795 to I650 9). In aerospace practice, parts are annealed at a set temperature of 1065 “C (1950 ‘%) and quenched in water w,ith one exception: parts under 2.5 mm (0. IO in.) thick may be air cooled or polymer quenched to minimize distortion. See table for soaking times. Note: approval of the cognizant engineering organization is required for annealing material in a straitt-hardened condition. such as ‘4 hard; for stress relieving; or for dimensional stabilization. Heat treating or slow cooling unstabilized grades between -170 to 8 I5 ‘C (875 to IS00 ‘%) is prohibited. except for 304L and 3 l6L
Stress Relieving. Parts can be relieved after uenchin to achieve dimensional stability. by heating to 230 to 400 “C (34 5 to 7 s 0 “F) for UP to several hours. depending on section size and without change in metallographic structure. In aerospace practice. parts are stress relieved at 900 ‘C (1650 %). and quenched in water. As an alternative, parts may be stress relieved at annealing temperatures. Sections under 2.5 mm (0. IO in.) thick may be air cooled to minimize distortion. Parts fabricated from steel in the strain-hardened condition, such as t/z hard. shall not be stress relieved without permission of the cognizant engineering authority. When stress relieving after welding. hold for 30 min minimum at the stress relieving temperature. Heat treating or slow cooling of unstabilized grades between 470 to 815 “C 187.5 to 1500 9) is prohibited. except for 304L and 316L. See table for soaking times Nitriding. Not recommended. Case seriously impairs corrosion resistance in most media. Case seldom more than 0. I27 mm (0.005 in.) deep. Only used in specialized applications where material must be nonmagnetic and have wear-resistant surface. if nitrided, parts must be in annealed condition to prevent flaking or blistering of nitrided case. All sharp comers should be replaced with radii of not less than I.59 mm (0.06 in.). Film of primarily chromium oxide. that protects stainless alloys from oxidation and corrosion, must be removed prior to nitriding. Accomplished by wet blasting, pickling. chemical reduction in reducing atmosphere. submersion in molten salt. or by one of several proprietary processes. If doubt exists that complete and uniform depassivation has occurred. further reduction of the oxide may be accomplished in Furnace by means of reducing hydrogen atmosphere or suitable proprietary agent. After depassivation, avoid contamination of surface bv finger or hand marking. Single-stage nitriding adequate at 525 to 550 ‘C (975 to 1020 ?) for 20 to 48 h (depending on case depth required). Dissociation rates for single-stage cycle are from 20 to 35%. Hardness is as high as 1000 to 1350 HK on surface. 48-h cycle
produces case extending to 0. I27 mm (0.005 in.) with approximately 800 to 1000 HK. Case will rapidly drop to 200 HK core hardness. at approsimately 0. I65 mm (0.0065 in.)
Recommended l l l l l l
Processing
Cold work Anneal and quench Remove surface contamination Stress relieve Depassivate (if nitriding) Nitride (if required)
Sequence
309s:
Soaking
Austenitic
Stainless
Times (Aerospace
Practice)
Diameter or thickness(a) of maximum section mm (in.) inclusive upro3010.100)
(if required)
over 2.50 10 6 25 (0. IO0 to 0.250) o\er 6.25 to 17.50 (0.150 to 0,500) o\er 12 50 to 25.00 (0.500 t0 I .00) 0\er~5.00t037..50~1.0010 1.50) over 3750 to 50.00 I I .50 to xlo, over50.00to62.5Ot~.00to7.50) o\~r62.SOto75.00(7.SOt03.OO) “\er75.00t3.00)
Steels / 743
Minimum soaking time Atmosphere furnace Salt bath min mln ‘0 15 15 60 7s 90 10s 170 (b)
17 I8 35 40 45 50 55 60 W
131 Tbckness ib minimum dimension of hea\ iest secuon of part or nested load of pans. tb) 2 25 h plus IS min forevq II 5 mm(0.S in )orincrementof 12.5 mm(0.S in.)over 75 mm (3 in ). tc) I h. 5 min pluj 5 min for eveq 12.5 mm (0.5 in.)or incremem of 11.5 10.5 in.) over 7S mm t 3 in.). Source: AAIS 2759/-I
Austenitic
Stainless Steels / 743
310 Chemical Composition.
AIsIjUNs
(s31000): 0.25 C. 2.00 Mn.
0.045 P, 0.030 S. I.50 Si. 19.00 to 22.00 Ni. 21.00 to 26.00 Cr
Similar Steels (U.S. and/or Foreign). AhlS 5694. 5695;
ASME SAl82. SA213. SA239. SA312. SA358. SA-103. SA109: ASThl 44167. A 182. AZ-IO. A213. A339. A276. A3 12. A31-1. A358. AA03. A-lO9. A173. AS I I, A632; FED QQ-S-763. QQ-S-766. QQ-W-423, STD-66; MU- SPEC MIL-S-862; SAE 1105 (30310): (Ger.) DIN I.-WI: (Fr., AFNOR Z I2 CNS 25.20; (Ital.) UNI X I6 CrNiSi 25 20. X 22 CrNi 25 20; (Jap.) JIS SUS Y 310: (U.K.) B.S. 310 S 2-l
Characteristics. sion and oxidatton
High heat resistant qualities. plus resistant to corroat high temperatures. Very ductile. Easily irelded
Forging.
Start forging at 1095 to 1130 ‘C (2005 to 22-lS v). Finish forging at 980 to 1010 ‘C ( I795 to I850 OF). Cool to black color in less than 3 min. using liquid quench if neccssq
Recommended Normalizing. Annealing.
Heat Treating
Practice
Do not normalize
Anneal at IO-IO to I I50 “C ( 1905 to 2 100 9) and hold at least t/z h. To guard against distortion of thin. delicate parts, leave ample room for expansion between parts. Stainless grades expand about t\i ice as much as carbon and low-alloy steels. 4110~ enough time for through heating after thermocouple has reached temperature. Stainless grades have approximately half the thermal conductivity ofcarbon and lou-alloy steels. Choice of atmosphere depends on finish desired and I+ hether surface stock uill be removed. For bright annealing. use vacuum or an atmosphere of hydra en or dissociated ammonia at dew point of -62 to -71 “C t-80 to -100 %R Parts must be thoroughly clean and dry. Inert gases argon and helium (although expensive) and nitrogen. with dew points of less than -5-l “C (-65 w, can be used. They lack the reducing effect of hydrogen. so slight discoloration in the form of chrome oxide can result. Salt. exothermic. or endothemuc atmospheres are satisfactory for nonbright annealing Salt is difficult to remove. and rinse quenching at 595 “C (I IO5 9) is not recommended. because interrupted quench at elevated temperature cannot be tolerated. Exothermic and endothermic atmospheres must be carefully controlled at equivalent carbon potential to avoid carbutization. which will seriously lower corrosion resistance. Same problem with atmosphere annealing. If oxidizing conditions are present, scale will form. Difficult to remove in subsequent descaling operations.
Cool rapidI\ from annealing temperature: no more than 3 min to black color. Section size determines quenching medium: water for heavy sections. air blast for intermediate sizes. and still air for thin sections. Carbides can precipitate at grain boundaries when parts are cooled too slowly betueen -I25 to 900 “C i79S to l6SO %. In aerospace practice. parts are annealed at a set temperature of 1065 “C (I950 ‘%, and quenched in Hater with one exception: parts under 2.5 mm (0. IO in.) thick may be air cooled or polymer quenched to minimize distortion. See table for soahing times. Note: approval of the cognizant engineering organization is required for annealing material in a suain-hardened condition. such as ‘15 hard; for stress relieving; or for dimensional stabilization. Heat treating or slow cooling unstabilized grades between -170 to 8 IS ‘C (875 IO IS00 ‘>FJ is prohibited. except for 3OAL and 3 l6L Stress RelieVing. Parts can be relieved after quenching to achieve dimensional stabiliQ. b! heating to 230 to -IO0 “C (-WI to 750 ?) for up to several hours. depending on section size and without change in metallographic structure. In aerospace practice. parts are stress relieved at 900 “C ( I650 ‘%). and quenched in water. As an alternative. parts may be stress relieved at annealing temperatures. Sections under 3.5 mm (0. IO in.) thick may be air cooled to minimize distortion. Parts fabricated from steel in the strain-hardened condition. such as % hard. shall not be stress relieved without permission of the cognizan; cneineering authority. When stress relieving after \+elding. hold for 30 min n;inimum at the stress relieving temperature. Heat treating or slo\\ cooling of unstabilized grades between 470 to 8 I5 ‘C (875 to IS00 OFI is prohibited. except for ?ML and 316L. See table for soaking times
Nitriding. Not recommended Case seriously impairs corrosion resistance in most media. Case seldom more than 0. I27 mm (0.005 in.) deep. Only used in specialized applications \h here material must be nonmagnetic and ha\e wear-resistant surface. If nitrided. parts must be in annealed condition to prevent flaking or blistering of nitrided case. ,411sharp comers should be replaced u ith radii of not less than I.59 mm (0.06 in.). Film of primarily chromium oxide. that protects stainless alloys from oxidation and corrosion. must be removed prior to nitriding. Accomplished by bet blasting, pickling. chemical reduction in reducing atmosphere, submersion in molten salt. or by-one of several proprietary processes. If doubt exists that complete and umtorm depassivation has occurred. further reduction of the oxide ma! be accomplished in furnace b> means of reducing hydrogen atmosphere or suitable proprietaq agent. After depassivation. avoid contamination of surface b!, Finger or hand marking. Single-stage nitriding
744 / Heat Treaters Guide adequate at 525 IO 550 ‘C (975 to 1020 %F) for 10 IO 48 h (depending on case depth required). Dissociation rates for single-stage cyzls are from 20 to 355. Hardness is as high as 1000 to I350 HK on surface. 43-h cqcls produces case extending to 0. I27 nun tO.005 in.) with approximateI> 800 to 1000 HK. Case uill rapidly drop to 200 HK core hardness. at approximateI> 0. I65 nun t0.006.5 in.)
310:
Recommended
o\rlr2.iOto62StO.l00toO350, wer 6.15 to 12.50 (0.250 to 0.5001 over I1 50 to 25.00 (0 500 to I.001 over 25.00 to 37.50 t I .W to I 50) o\er 37.50 to 5O.Wt I 50 to 2.OOI o\er 50.W to630 12.00 to 2 5Ot otrr62 SO to 75 0012 511to 3.W) o\rr75.Wt3.W)
l l l l l l
Processing
Cold lrork Anneal and quench Remove surface contamination Stress relieve Depassivate (if nitriding) Nitride lif rcqutred)
Sequence
(if required)
Soaking Times (Aerospace Practice)
Diameteror thickness(a) of maximum section mm (in.) inclusive upro2.50ff~ 100)
~a) Thiilaesj
hlioimum soaking time Atmosphere furnace Salt batb mitt mia ‘0 25 15 60 75 90 IO5 1x tbr
17 18 35 -lo -Is SO 55 60 (Cl
ISminimutn dimension of heavwtt sectinn of part or nested load of parts. fbrl.25hplui 1Sntinforevr~ I~..immtO5in.~orincrrmmtof12.Snun(O.Sin.~o~er 75mm13in.l.t~) I h..‘,nljnplus5minforr\~~ 13.Smmt0.5in.)orincrementof 12.5 10.5 in joker 75 mm 13 in.). Source. AhlS 275CN-1
744 / Heat Treaters
Guide
310s Chemical
Composition.
~1sIjUNs (S31008): 0.08 c. X0
MI.
0.045 F! 0.030 S. 1.50 Si. 19.00 to 32.00 Ni. 24.00 to 26.00 Cr
Similar Steels (U.S. and/or Foreign). MS WI, 5577. 5577. 5651: ASME SA2-10. SA-179; ASThl Al67. A240. ,X76. Ml-l. A473. A479. A51 I. AM-4
Characteristics.
AS80; SAEJ405
t303lOSj
High heat resistant qualities. plus resistant to corroat high temperatures. C’eq ductile. Easil! welded
sion and oxidation
Forging.
Start forging at 1095 to 1230 ‘:‘C (2005 to 2115 “F). Finish forg,ing at 980 to 1010 “C ( I795 to I850 “FI. Cool to hlnck color in less than 3 nun. using liquid quench if necessag
Recommended Normalizing. Annealing.
Heat Treating
Practice
Do not normalize
Anneal at lo-10 to I I SO “C (’ I905 to 2 IO0 ‘“F) and hold al least !I! h. To guard against distortion of thin. delicate parts. 1eat.e ample room for expansion hetbbeen parts. Statnless grades expand ahout III ice as much as carbon and lo\%-allo, steels. Allow enough time for through heating after thermocouple has reached temperature. Stainless grades hats approximately half the thermal conducti\ ity of carbon and low-allo! steels. Choice of atmosphere depends on finish desired and \chether surface stock will he removed. For bright annealinp. use vacuum or an atmosphere of hydrogen or dissociated ammonia at den point of 42 to -74 “C t-80 to -100 “F). Parts must be thoroughI) clean and dc. Inert gases argon ad helium (although expensive) and nitrogen. with dew points of less than -5-l “C f-65 “F). can he used. The) lack the reducing effect of hydrogen. so slight discoloration in the form of chrome oxide can result. Sah. ewthermic. or endothermic atmospheres are sat&facto9 for nonbright annealing. Salt is difficult IO remove. and rinse quenching a~ 595 “C ( I IO5 “F) is not recommended. because interrupted quench a~ eknted temperature cannot he tolerated. Exothemuc and endothermic atmospheres must he carsfull> controlled a~ equivalent carbon potential to avoid carhuriration. \\ hich will seriousI! lower corrosion resistance. Same prohlem with atmosphere annealing. If oxidizing conditions are present. scale will form. Difficult IO remove in subsequent descalinp operations. Cool rapidly from annealing temperature: no more than 3 tin to blnch color. Section size deremlines quenching medium: iiater for heavy sections. air blast for intermediate sizes. and still air for thin sections. Carhides can precipitate at grain houndaries I\ hen parts are cooled too slowI> between 425 IO 900 “C (795 to I650 “F).
In aerospace practice. parts are annealed at a set temperature of 1065 ‘C (I950 “F) and quenched in \tater \rith one exception: parts under 3.5 mm (0 IO in.) thick may he air cooled or polymer quenched to minimize distortion. See table for soaking times. Note: approval of the cognkant engineerin_e organization is required for annealing material in a strain-hardened condition. such as !‘j hnrd: for stress relieving; or for dimensionti stahilizatton. Heat treating or slow cooling unstabilized grades between 470 to YIS “C (875 to IS00 ‘F) is prohihited. escept for BO4Lsnd 316L Stress l?eh?Ving. Parts can he relieved after quenching to achieve dimensional stability. by heating to 230 to JO0 “C (435 to 750 “F) for up IO se\eral hours. depending on section size. and without change in metallographic structure.
Ln aerospace practice. parts are stress relieved at 900 “C ( I650 “Fj. and quenched in water. As an altsmative. parts may he suess relieved at anrlealing temperatures. Sections under 2.5 mm (0. IO in.) thick may he air cooled to minimize distortion. Parts fabricated from steel in the strain-hardened condition. such as t/S bard. shall not be stress relieved uithout permission of the cognizant engineering authority. When stress relieving after welding. hold for 30 min minimum at the stress relieving temperature. Heat treating or slow cooling of unstahilired grades between 470 to 815 “C (875 to IS00 “FJ is prohihitsd. except for 304L and 316L. See table for soaking times
Nitriding. Not recommended. Case seriously impairs corrosion resistance in most media. Case seldom more than 0.127 mm (0.005 in.) deep. OnI) used in specialized applications where material must he nonmagnetic and have \rrx-resistant surface. If nitrided, parts must be in annealed condition to prevent Flaking or blistering of nitrided cilse. All sharp comers should be replaced u ith radii of not less than I .59 mm (0.06 in.). Film of primarily chromium oxide. that protects stainless alloys from oxidation and corrosion, must he removed prior to nitriding. Accomplished by wet blasting. pickling. chemical reduction in reducing atmosphere. suhmersion in molten salt. or hy one of several proprietar) processes. If doubt exists that complete and uniform depassivation has occurred. further reduction of the oxide ma> be accomplished in furnace by means of reducing hydrogen atmosphere or suitable propriety agent. After depassivation. avoid contamination of surface hy finger or hand marking Single-stage nitriding adequate at 525 to 550 “C (975 to 1020 “F) for 20 to 18 h (depending on case depth required). Dissociation rates for single-stage cycle are from 20 to 3%. Hardness is as high as 1000 to 1350 HK on surface. 18-h cycle produces case extending to 0. I37 mm (0 005 in.) with approximately 800
to 1000 HK. Case will rapidly drop to 200 HK core hardness. at approximately 0. I65 mm (0.0065 in.)
Recommended l l l l l l
Processing
Cold work Anneal and quench Remove surface contamination Stress relieve Depassivate (if nitriding) Nitride (if required)
Sequence
c’if required)
310s:
Soaking
Austenitic
Stainless
Times (Aerospace
Practice)
Minimum Atmosphere furnace min
Diameter or thickness(a) of ma&mu section mm (in.) inclusive
“\rr’.solo6.2.ilo.l00toO~5o, ok~rfi.3 over
IO 12.50
130~0.30
to 25 00 (0.500
"\er2s.ooto37.s0f
1.00l0
IO
0.500)
to 1.00, 1.50,
0~37.SOto50001 I.SOro2 001 o\er SO.00 1062.50f’OO to 2 501 o~rr67.501o75.00t~.SOto 3.00) 0\er75.00t3.00~
soaking
Steels / 745
time Salt bath min 17 18 3S 40 45 so 5.5 60 ICI
ta) Thisknejs 1s mimmum dimenston of hea\ iest section of part or nested load of parts. tb)2.2Shplui ISminiore\ery 12.Smm10.Sin.1orincrementof I2 Smm(0.5in.)o\er 75 mmt3 in ).tc) I h.5 minplusS mtn fore\ery 12 9 mmtO.S in )orincrementof 12.5 to.5 in.)o\er7S mmt3in.1. Source: .AhlS275W
Austenitic
Stainless
Steels / 745
314 Chemical
Composition. AISI/tJNS (S31400): 0.25 C. 7.00 Mn. I.50 to 3.00 Si, 23.0 to 26.00 Cr. 19.00 to 22.00 Ni. 0.0-45 P. 0.030 S
Similar
Steels (U.S. and/or Foreign). AM W1, 5652: ASThl A276. A3l-l. A173. AS80; SAE J-t05 (3031-t); tGer.) DM 1.4841: tFr.) AFNOR Z I2 CNS 25.20: (Ital.) CINI X 16CrNiSi 25 20. X 22 CrNi 3-S 20; tJap.) JIS SUS Y 310: (U.K.) B.S. 310s 2-l
Characteristics. Highest heat resistance properties of all the chromium-nickel steels. Essentially nonmagnettc. Subject to embtittlement u hen exposed for long periods of time to temperatures of 650 to 8 I5 ‘C t I200 to I SO0 “F). Brittleness only evident at room temperature and can be eliminated by holding steel at 980 to IO-IO “C t 1795 to 1905 “F). I to 2 h Forging.
Start forging at IO-IO to I I20 ‘C t 1905 to 2050 “F). Do not forge after forging stock drops below 925 “C t 1695 “F). Cool to black color in less than 3 min. using liquid quench if necessary
Recommended Normalizing. Annealing.
Heat Treating Practice
Do not normalize
Anneal at I IS0 “C (2 IO0 “F). To guard agamst distortion of thin, delicate parts. leave ample room for expansion between parts. Stainless grades expand about twice as much as carbon and low-alloy steels. Allou enough time for through heating after themlocouple has reached temperature. Stainless grades have approximateI>; half the thermal conductivity of carbon and low-alloy steels. Choice of atmosphere depends on fmish desired and whether surface stock will be removed. For bright annealing. use vacuum or an atmosphere of hydrogen or dissociated ammonia at dew point of-62 to -74 “C t-80 to -I 00 “F). Parts must be thoroughly clean and dry. Inert gases argon and helium t,althouph expensive) and nitrogen. with deu points of less than -S-l ‘C t-65 “F). can be used. The) lack the reducing effect of hydrogen. so slight discoloration in the fomm of chrome oxide can result. Salt. exothermic. or endothermic atmospheres are satisfactory for nonbright annealing. Salt is difftcult to remove. and rinse quenching at 595 “C t I IO5 “F) is not recommended. because interrupted quench at elevated temperature cannot be tolerated. Exothcrmic and endothermic atmospheres must be carefully controlled at equivalent carbon potential to avoid carburiration. u hich will seriously lower corrosion resistance. Same problem with atmosphere annealing. If oxidizing conditions are present. scale I&ill form. Difficult to remove in subsequent descaling operations.
Cool rapidI> from annealing temperature: no more than 3 mm to black color. Section stze determines quenching medium: water for heavy sections. air blast for intemtediats sizes. and still au for thin sections. Carbides can precipitate at grain boundaries H hen parts are cooled too slowly between 125 to 900 ‘C (795 to I650 “F). In aerospace practice. parts are annealed at a set temperature of 1095 “C (2005 “F) and quenched in water with one exception: parts under 2.5 nun (0. IO in.) thick may be air cooled or pal) mer quenched to minimize distortton. Parts fabricated from steel in a strain-hardened condition. such as \> hard. shall not be annealed. stress relieved. or dimensionally stabilized I$ ithout permtssion of the cognizant engineering authority. Also, heat treating or slow cooling unstabilized grades between -I70 to Xl5 “C (875 to IS00 “F) IS prohibited. c\cept for 3O-lL and 3 I6L. See table for soakinp limes StreSS k?k?Ving. Parts can be relir\ed atier quenching to achieve dimensional stabilib. b> heating to 230 to 400 “C (4-U to 750 OF) for up to several houri. depending on section size and without change in metallographic structure. In aerospace practice. parts are stress relieved at 900 “C ( I650 “F). and quenched in Uater. As an altsmattve. parts may be stress relieved at annealing temperatures. Secttons under 2.5 mm (0. IO in.) thick may be air cooled to minimize distortion. Parts fabricated from steel in the strain-hardened condition. such as ‘s’, hard. shall not be stress relieved without pemission of the cognizan~sngineering authority. When stress relieving after v~elding. hold for 30 mtn minimum at the stress relieving temperature. Heat treating or slo\\ cooljnp of unstabilized grades between 470 to 8 IS “C (875 to IS00 “F) is prohtbned. except for 304L and 3lhL. See table for soaking times
Nitriding. Not recommended. Case seriousI> impairs corrosion resistance in most media. Case seldom more than 0. I27 mm (0.005 in.) deep. OnI) used in specialized applications where material must be nonmagnetic and have wear-resistant surface. If nittided. parts must be m annealed condition to prevent Flaking or blistering of nitrided case. All sharp comers should be replaced \v ith radii of not less than I .S9 mm (0.06 in.). Film of pnmarily chrommm oxide. that protects stainless alloys from oxidation and corrosion. must be removed prior to nitriding. Accomplished by wet blasting. pickling chemical reduction in reducing atmosphere. submersion in molten salt, or b:\ one of several propriet+ processes. If doubt exists that complete and umfoml depassivation has occurred. further reduction of the oxide ma) be accomplished in furnace by means of reducing hydrogen atmosphere or suitable proprietary agent. After depassivation, avoid con-
746 / Heat Treaters
Guide
tamination of surface by finger or hand marking. Single-stage nitriding adequate at 525 to 550 “C (975 to 1020 “F) for 20 to 38 h (depending on case depth required). Dissociation rates for single-stage cycle are from 20 IO 35%. Hardness is as high as IO00 to 1350 HK on surface. 48-h cycle produces case extending to 0. I27 mm (0.005 in.) with approximately 800 to 1000 HK. Case will rapidly drop to 200 HK core hardness, at approximately 0. I65 mm (0.0065 in.)
Recommended
Processing
Cold work Anneal and quench Remove surface contamination Stress relieve Depassivate (if nitriding) Nitride (if required)
Sequence
(if required)
314:
Soaking
Times (Aerospace
Diameteror thickness(a) of maximum section mm (in.) inclusive
Practice)
Mnimum Soaking time Atmosphere furnace tilt bath min min
upto’.so(o.lcoJ
20
o~er?.501o6.~5~0.1001o0.150) 0w 6.25 IO 12.50 (0.250 to 0.500) over I2.50to X.00 (0.500 IO I.001 o~rlr7-5.00t037.50~I.~X)t0 1.50,
35 15 60 7s
17 18 35 40 35
over 37.50 to SO.00t I .SOto 2.OOt o\er SO.00to62.50t2.00 to 7.50) over61.50to75.00(2.50to3.00) over 75.00 t ?.OOt
90 10s 120 ih)
so 55 60 CC)
~a) Thickness is minimum dimension of heaviest section of part or nested load of parts. tb) 2.25 hplus IS mm foretery 12.5 mmi0.S intorincrementof 12.Smm(O.S in.)over 75 mmt3 in.).(c) I h.5 nlinplus5 min forever) 12.5 mm(0.5 in.)orincrementof 12.5 10.5 intoner 75 mm (3 in.). Source: AhlS 27591-t
746 / Heat Treaters
Guide
316 Chemical
Composition. AISI/UNS (S31600): 0.08 C. 2.00 Mn, l.OOSi, 16.OOto 18.OOCr. lO.OOto l-l.00 Ni.O.045 P.O.03OS. 2.00 to3.00 MO
Similar Steels (U.S. and/or Foreign). AMS ss2d. ~~73. ~6-18. 5690. 5691; ASME SAl83, SAl93. SAl9-1. SA313. S.4’10. SA2-19. SA3 12. SA320, SA358. SA376. SA303. SA309. SA-430. SA-179. SA688; ASTM A167.A182,.A193.A19-I.A213.A1~0.A2~9.A269,A276,4312. A313. A3l-I. A320. A358. A368. A376. A403.4109. A130. A473.4478. A479: FED QQ-S-763. QQ-S-766. QQ-W-323; MIL SPEC hllL-S-862. MIL-S-5059; SAE J-IO5 (303 16): t Ger.) DfN I.440 I : (Fr.) AFNOR Z 6 CND 17.1 I: (1tal.j UNI X 5 CrNiMo I7 I?: (Jap.) JIS SUS 316. SUH 309. S1lSY316:(Swed.)SSt~2347;(U.K.)B.S.316S 16.316s 18.316S25. 316S26.316S30.316S40.316S4I.En.58H Characteristics.
Superior corrosion resistance vs other chroniumnickel steels. when exposed to man) types of chemical corrodents as well as marine atmospheres. Superior creep strength at ele\atsd temperatures. Very resistant to corrosion hq sulfuric acid
Forging. Start forging at I IS0 to 1260 “C (2100 to 3300 “F). Do not forge after forging stock drops helow 925 “C t I695 OF). Cool to black color in less than 3 min. using liquid quench if necess+
Recommended Normalizing. Annealing.
Heat Treating
Practice
Do not normalize
Anneal at 1010 to I I20 “C (1905 to 2050 “F). Within this range, lower temperatures are sufficient for sheet and strip. but higher temperatures should he used for plates and bars. To guard against distortion of thin. delicate parts. leave ample room for expansion between parts. Stainless grades expand about twice as much as carbon and low-allo! steels. Allow enough time for through heating after thermocouple has reached temperature. Stainless grades have approximatelq half the thermal conductivity of carbon and lou-alloy steels. Choice of atmosphere depends on finish desired and u hether surface stock nilI be removed. For bright annealing, use vacuum or an atmosphere of hydrogen ordissociated ammonia at dewpointof-62 to-71°C t-80 to-IOO’F). Parts must he thoroughI) clean and dry. Inert gases argon and helium (although expensive) and nitrogen. with dew points of less than -5-I “C (-65 “F), can he used. They lack the reducing effect of hydrogen. so slight discoloration in the form of chrome oxide can result. Salt. exothermic. or endothermic atmospheres are satisvdctory for nonbright annealing. Salt is difticult to remove. and rinse
quenching at 595 “C (I IO5 “F) is not recommended, because interrupted quench at elevated temperature cannot be tolerated. Exothermic and endothermic atmospheres must be carefully controlled at equivalent carbon which will seriously lower corrosion potential to avoid carburization. resistance. Same pro&m with atmosphere annealing. If oxidizing conditions are present. scale will form. Difficult to remove in subsequent descaling operations. Cool rapidly from annealing temperature; no more than 3 min to black color. Section size determines quenching medium: water for heavy sections. air blast for intermediate sizes. and still air for thin sections. Carbides can precipitate at grain houndaries when parts are cooled too slowly between 425 to 900 “C (79.5 to 1650 “F). In aerospace practice, parts are annealed at a set temperature of 1095 “C (2005 OF) and quenched in water Hith one exception: parts under 2.5 mm (0. IO in.) thick may be air cooled or polymer quenched to minimize distortion. Parts fabricated from steel in a strain-hardened condition. such as l/z hard, shall not be annealed. stress relieved, or dimensionally stabilized without permission of the cognizant engineering authority. Also, heat treating or slow cooling unstabilized grades between 470 to 815 “C (875 to IS00 “F) is prohibited. except for 303L and 316L. See table for soaking times StreSS RelieVing. Parts can be relieved after quenching to achieve dimensional stability. hy heating to 230 to 400 “C (445 to 750 OF) for up to several hours. depending on section size and without change in metallographic structure.
In aerospace practics. parts are stress relieved at 900 “C ( 1650 “F). and quenched in \\ater. As an altemnti\e, parts may he stress relieved at annealing temperatures. Sections under 2.5 mm (0.10 in.) thick may be air cooled to minimize distortion. Parts fabricated from steel in the strain-hardened condition. such as t/2 hard. shall not he stress relieved without permission of the cognizant engineering authority. When stress relieving after uelding. hold for 30 tin minimum at the stress relieving temperature. Heat treating or slo\\ cooling of unstabilized grades between 370 to 815 “C (875 to IS00 “Fb is prohibited. except for 301L and 316L. See table for soaking times
Nitriding. Not recommended. Case seriously Impairs corrosion resistance in most media. Case seldom more than 0. I27 mm (0.005 in.) deep. Only used in specialized applications where material must be nonmagnetic and have Hear-resistant surface. If nitrided. parts must be in annealed condition to prevent flaking or blistering of nitrided case. All sharp comers
Austenitic should be replaced with radii of not less than I.59 mm (0.06 in.). Film of primarily chromium oxide, that protects stainless alloys from oxidation and corrosion, must be removed prior to nitriding. Accomplished by wet blasting. pickling, chemical reduction in reducing atmosphere. submersion in molten salt. or by one of several proprietary processes. If doubt exists that complete and uniform depassivation has occurred, further reduction of the oxide may be accomplished in furnace by means of reducing hydrogen atmosphere or suitable proprietary agent. After depassivation. avoid contamination of surface by tinger or hand marking. Single-stage nitriding adequate at 525 to 550 “C (975 to 1020 “F) for 20 to 38 h (depending on case depth required). Dissociation rates for single-stage cycle are from 20 to 35%. Hardness is as high as 1000 to 1350 HK on surface. 48-h cycle produces case extending to 0. I27 mm (0.005 in.) with approximately 800 to 1000 HK. Case will rapidly drop to 300 HK core hardness. at approximately 0. I65 mm (0.0065 in.)
Recommended l l l l
Processing
Cold work Anneal and quench Remove surface contamination Stress relieve
Sequence
(if required)
l l
Stainless
Steels / 747
Depassilate (if nitriding) Nitride (if required)
316:
Soaking
Times (Aerospace
Diameter or thickness(a) of maximum section mm (in.) inclusive ober 2.50 to6.25 tO.IO0toO.ZiO) wcr 6.25 to I2.50 (0.250 to 0.500) i)\cr 12.50 to 25 00 (0.500 to I .OO) o\ er 25.00 to 37.50 I I.00 10 I SO) ober 37.50 toSO.OOt I .SO to 2.00) over 50.00 to62.50 t7.00 to 2.50) over6250 to 75.0012.SO to 3.00) o\er75.0013.00)
Practice)
Minimum soaking time Atmosphere furnace Salt bath min min 20 ‘5 15 60 75 90 10s 120 tb)
17 18 3s 40 15 SO 55 60 (Cl
(a) Thickness is minimum dimension of heaviest section of part or nested load of parts. (b) 2.29 h plus IS min for every 12.5 mm t0.S in.) or increment of 12.5 mm (0.S in.) over 75 mm(3 in.).(c) I h. Smmplus.i, mm lorevery 12.5 mm(O.Sin.)orincrementof 12.5 (0.5 in.)over 75 mm (3in.j Source: AMS 27591-t
Austenitic
Stainless Steels / 747
316F Chemical Composition.
AIWUNS (S31620):0.08 C. 2.00 Mn,
l.OOSi. 16.OOto 18.OOCr. lO.OOto 14.00Ni,0.200P.0.100Smin, 2.50 MO
Similar Steels (U.S. and/or Foreign). Characteristics. to improve machining ic screw machines
I.75 to
AMS 5649
Similar to type 3 16. except elements have been added and nonseizing characteristics. Suitable for automat-
Forging. Start forging at 1205 “C (2200 “F). Do not forge after forging stock drops below 925 “C (1695 “F). Cool to black color in less than 3 min. using liquid quench if necessary Recommended Normalizing. Annealing.
Heat Treating
Practice
Do not normalize
Anneal at 1095 “C (2005 “Fj. To guard against distortion of thin. delicate parts. leave ample room for expansion between parts. Stainless grades expand about twice as much as carbon and low-alloy steels. Allow enough time for through heating after thermocouple has reached temperature. Stainless grades have approximately half the thermal conductivity of carbon and low-alloy steels. Choice of atmosphere depends on finish desired and whether surface stock will be removed. For bright annealing. use vacuum or an atmosphere of hydrogen or dissociated ammoma at dew point of -62 to -74 “C (-80 to - IO0 OF). Parts must be thoroughly clean and dry. Inert gases argon and helium (although expensive) and nitrogen. with dew points of less than -5-t “C (-65 OF). can be used. They lack the reducing effect of hydrogen, so slight discoloration in the fomm of chrome oxide can result. Salt. exothermic, or endothermic atmospheres are satisfactory for nonbright annealing. Salt is difftcult to remove. and rinse quenching at 595 “C (I I05 “F) is not recommended, because interrupted quench at elevated temperature cannot be tolerated. Exothermic and endothermic atmospheres must be carefully controlled at equivalent carbon potential to avoid carburization. which will seriously lower corrosion resistance. Same problem with atmosphere annealing. If oxidizing conditions are present. scale will form. Difftcult to remove in subsequent descaling operations.
Cool rapidly from annealing temperature; no more than 3 min to black color. Section stze determines quenching medium: water for heavy sections. air blast for intermediate sizes, and still air for thin sections. Carbides can precipitate at grain boundaries when parts are cooled too slowly between 425 to 900 “C (79s to I650 “F). In aerospace practice, parts are annealed at a set temperature of 1095 “C (2005 “F) and quenched in water with one exception: parts under 2.5 mm (0.10 in.) thick may be air cooled or polymer quenched to minimize distortion. Parts fabricated from steel in a strain-hardened condition, such as l/r, hard. shall not be annealed. stress relieved, or dimensionally stabilized without permission of the cognizant engineering authority. Also. heat treating or slow cooling unstabilized grades between 470 to 815 “C (875 to IS00 “F) is prohibited. except for 304L and 316L. See table for soaking times Rehhlg. Parts can be relieved after quenching to achieve StreSS dimensional stability. by heating to 230 to 100 “C (445 to 750 “F) for up to several hours. depending on section size and without change in metallographic structure. In aerospace practice. parts are stress relieved at 900 “C (1650 “F), and quenched in water. As an alternative. parts may be stress relieved at annealing temperatures. Sections under 2.5 mm (0. IO in.) thick may be air cooled to minimize distortion. Parts fabricated from steel in the strain-hardened condition. such as ‘/2 hard. shall not be stress relieved without permission of the cognizant engineering authority. When stress relieving after welding, hold for 30 min minimum at the stress relieving temperature. Heat treating or slow cooling of unstabilized grades between 470 to 815 “C (87s to 1500 “F) is prohibited, except for 304L and 316L. See table for soaking times
Nitriding. Not recommended. Case seriously impairs corrosion resistance in most media. Case seldom more than 0. I27 mm (0.005 in.) deep. Only used in specialized applications where material must be nonmagnetic and have wear-resistant surface. If nitrided, parts must be in annealed condition to prevent flaking or blistering of nitrided case. All sharp comers should be replaced with radii of not less than I .59 mm (0.06 in.). Film of primarily chromium oxide. that protects stainless alloys from oxidation and corrosion. must be removed prior to nitriding. Accomplished by wet blasting, pickling. chemical reduction in reducing atmosphere. submersion in
748 / Heat Treaters Guide molten salt. or bj one of several propriety processes. If doubt ssists that complete and uniform depassivation has occurred. further reduction of the elide may be accomplished In furnace b> means of reducing hydrogen atmosphere or suitable proprietary agent. After depassivation. avoid contamination of wrface by finger or hand marking. Single-stage nitridinp adequate at 57-S to 550 “C (c)75 to 10X “F) for 20 to 48 h tdcpending on case depth required). Dissociation rates for single-stage cycle are from 20 to 3S00. Hardness is as high as 1000 to 1350 HK on surface. 48-h cycle produces case estending to 0. I27 mm t0.005 in.) u ith approximatel) 800 to 1000 HK. Case will rapidly drop to 200 HK core hardness. at approximately 0. I65 mm (0.0065 in.)
Recommended
Processing
Cold work Anneal and quench Remove surface contamination Stress relieve Dcpassivate (if nitriding) Nitride (if required)
Sequence
(if required)
316F:
Soaking Times (Aerospace Practice)
Diameteror thickness(a) of maaimum section mm (in.) inclusive upl0~.5010
1001
o~er~501o675~0.1001o0.2.50~ over 6.25 to 12.50 102.50 to 0.500~ over 12.50 10 25.00 (0.500 10 1.00) oler ~S.OOro 37.50( I 00 to 1.50, o\er 37.SOio5O OO( I 5Oto 2.00) o\er50.001o62501’.001o2.S0, over 62.50 to 75 00 I I.SO to 3.00) o\er 75.001300~
Minimum soaking Atmosphere furnace min 10 45 6s 80 95 I10 125 I40 IC)
time(b) Salt bath min 37
38 55 60 65 70 7S 80 (d)
(il) Thickness ii nummum dimenGon of hra\ lest section of pan or nested load of parts. (hi Parts should he held forsufticient time toensure that centerofmost mmsibesection has reached temperamre and necessary transformation and diffusion hare taken place. (c)Z h.3Sminplus 15minfore\ew l2.5n~~~O.SOin.)orincrementof l?SOmm(O.50 in ) o\er 75.0 mm 13 in.). td) I h. 25 min plus 5 ntin for ebery 12.50 mm (0.50 in.) or incrementof 12.5 mm 10 SOin.1o~er7S.On~,(3 in.). Source: AMS1_759/4
748 / Heat Treaters
Guide
316H Chemical Si. 16.00
Composition.
to 18.00
Cr. 10.00
Recommended
AISIpJNS: to l-1.00
Heat Treating
I .OO S. 2.00 to .1.00 klo
0.0-l to 0. IO C. 2.00 hln.
Ni. 0.045
P. 0.035
Practice
Annealing. In aerospace practice. parts are amWaled at a set temperature of 1095 “C tXOS “F) and quenched in irater with one exception: parts under 7.5 mm (0. IO in.) thick ma! be air cooled or pol>mcr quenched to minimize distortlon. Parts fabricated from steel in a strain-hardened condition. such as t/r, hard. shall not be annealed. stress relieved. or dimensionall! stabilized without permisslon of the copmzant engineering authontj. Also. heat treating or SIOU cooling unstabilized grades between 470 to 8 IS ‘T (875 to IS00 JF) is prohibited. except for 304L and 316L. See table for soaking times SW?SS k?hhg. In aerospace practice. parts are stress relked at 900 “C t 1650 “F). and quenched in ~aater. As an alternative, parts may be stress relieved at annealing temperatures. Sections under 2.5 mm (0. IO in.) thick may be air cooled to minimize distortion. Parts fabricated from steel in the strain hardened condition. such as !s? hard. shall not be stress relieved without permission of the cognizant engineering authority. When stress relking after welding. hold for 30 min minimum at the stress relieving temperature. Heat treating or slog cooling of unstabilized grades bet\\een 470 to 8 IS “C i875 to I SO0 “F) is prohibited. except for 304L and 3 IhL. See table for soaking times
316H:
Soaking
Times (Aerospace
Diameteror thickness(a) of mrsimum section mm (in.) inclusive “plo2.solo IWJ o\rr2.soto6Y-IO
looraO’5oJ
,vcr h 2S to II!.SO 10 150 10 0.5001 0i-x 12.50 lo 25.00 IO.500 I0 I.001 o\er2S.tX)to37.50(1.00to I.501 o~rr37.S0roSO~t1.SOto2.tX)~ o~erS0.OOro61 SO~2.00~0?!0~ o\er62.501o7S W~2.SO1o3.00~ o\rr7SOO13001
Practice)
hlinimum soaking lime(b) Atmosphere furnace Salt bath min min 40 -IS 65 80 9s II0 I25 I40 ICJ
37 38 5.5 60 65 70 7s 80 W
18) Thichness is minimum dimsnsion of hen\ IC~Isection of part or nested load of pllrts. I b I Parts should be held for rufticient time IOensure that center of most massive section has reached wmperarure and necessq trans.formstion and diffusion have taken place. (c)1 h. 35 minplus IS nunfore\cw 12.Smm~O.SOin.)orincrementof 12.5Omm(O.50 in.) o\er 75 0 null 13 in.). id) I h. !S rmn plus 5 min for ewy 12.90 mm (0.50 in.) or increment of IZ S mm tO.SOin.lo\er7S.Omm (3 in.). Source: AMS 2759/J
748 / Heat Treaters
Guide
316L (S31603): 0.030 C. 2.00 hln. l.OOSi. 16.00 to 18.OOCr. 10.0010 l-l.00Ni.0.015 P.0.030S.2.00to3.00 hlo
hllL SPEC hIIL-S-862: SAE J-IOS (30316 L,: (Ger.) DrN 1.4404; (Fr.) AFNOR Z 2 CND 17.11: (Ital.) UN1 X 2 CrNihlo I7 12; (Jap.) JIS SUS 316L.SL~H310:(S\~ed.,SSt~2318:tI~.K.)B.S.316S 12.316s 14.316 S~2.316S2~.316S29.316S30.316S31,316S37.316S82.S.537
Similar Steels (U.S. and/or Foreign). AhlS 5507.5653; AShiE SA 182. SA2 13. SA240. SA2-19. SA3 I?. SA403. SA-179. SA688: ASThl 4167. Al8’. A213,AXO. A24Y.A26Y. A?76.A312,A314.A403.A473. A178. A47Y. A5 I I. AS54 A580. A632. X688: FED QQ-S-763. QQ-S-766:
Characteristics. Similar to type 316. except more resistant to interpranular corrosion after welding or stress relieving. Recommended for parts which are fabricated by \\elding and cannot be subsequently anwaled GeneralI> limited IO WIT ice temperatures up to 125 “C (800 “F)
Chemical
COIIIpOSitiOn.
AISljUNs
Austenitic Forging.
Start forging at I IS0 to 1260 “C i2 IO0 to 2300 “F). Do not forge after forging stock drops below 925 ‘C (I695 “F)
Recommended Normalizing.
Heat Treating
Practice
Do not normalize
Annealing.
Anneal at 1010 to I I05 “C ( I905 to 7025 “Fj. Use I040 “C ( I905 “F) minimum for maximum ductility. Parts can be air cooled from annealing temperature. Water quenching not necessary. Slow cooling can occur through the 815 to 375 “C (IS00 to 795 “F) range for up to 3 h, without subsequent danger of susceptibility to intrrgranular corrosion in natural atmospheric environments. In aerospace practice, parts are annealed at a set temperature of I095 “C (ZOOS “F) and quenched in water with one exception: parts under 2.5 mm (0. IO in.) thick may be air cooled or polymer quenched lo minimize distortion. Parts fabricated from steel in a strain-hardened condition. such as ‘12 hard. shall not be annealed. stress relieved. or dimensionall> stabilized without permission of the cognizant engineering authority. Also, heat treating or slow cooling unstabilized grades between -170 to 815 “C (875 to 1500 “F) is prohibited, except for 30-&L and 3 l6L. See table for soaking times
Stabilizing. Becauss type 3 l6L contains mol> bdenum. it is susceptible to sigma-phase formation as a result of long exposure 31 650 to 870 “C (IX0 to 1600 “F). Corrosion resistance improved b> employing a slabilizing treatment (ASTM ,436X). consisting of holding at 885 “C t 1615 “F) for 2. h prior IO stress relies ing at 675 “C ( I215 “F) Nitriding. Rare. Not recommended. Case serious11 impatrs corrosron resistance in most media. Case seldom more than 0. I37 mm (0.005 in.) deep. Only used in specialized applications where material must be nonmagnetic and have wear-resistant surface. If nitrided. parts must be m annealed condition IO pre\ent flaking or blistering of nitrided case. All
Steels / 749
sharp comers should bs replaced with radii of not less than I .SY mm (0.06 in.). Film of ptimaril~ chromium oxide. that protects stainless alloys from oxidation and corrosion. must be removed prior to nitridinp. Accomplished bk wet blasting. pickling. chemical reduction in reducing atmosphere. submersion in molten salt. or b) one of several proprietary processes. If doubt exists that complete and uniform dcpassivalion has occurred. further reduction of the oxide ma) be accomplished in furnace by means of reducing hydrogen atmosphere or suitable proprietary agent. After depassivation. avoid contaminaGon of surface by finger or hand marking. Singlestage nitriding adequate at 525 IO 550 “C (975 to 1020 “F) for 10 to 48 h (depending on case depth requiredj. Dissociation rates for single-stage cycle are from 20 to 35%. Hardness is as high as 1000 Lo 1350 HK on surface. 48-h cycle produces case extending IO 0.127 mm (0.005 in.) with approximately 800 to 1000 HK. Case will rapidly drop to 300 HK core hardness. a1 approximatel) 0. I65 mm (0.0065 in.)
Recommended l l l l
Relieving. In aerospace practice. parts are stress relieved at Stress 900 “C (I650 “F). and quenched in water. As an alternative. parts ma! be stress relieved at annealing temperatures. Sections under 2.5 mm (0. IO in. I thick may be air cooled to minirmze distortion. Parts fabricated from steel in the strain-hardened condition. such as !‘z hard. shall not be stress relie\cd Hithout permission of the cognizant engineering authorit). When stress relieving after welding, hold for 30 min minimum at the stress reliel ing temperature. Heat treating or slon cooling of unstabilized grades between 470 to 815 “C (875 to 1500 “F) is prohibited. except for 3O-lL and 316L See table for soaking times
Stainless
l
Processing
Cold work Anneal and cool Stabilize and stress relie\c Depassivate tifnitriding) Nitride (if required)
316L:
Soaking
Sequence
(if necessary)
Times (Aerospace
Diameter or thickness(a) of maximum section mm (in.) in&site "plo~.5oro.lool 01 er 2.50 to 6.25 to. loo to 0.250) o\cr 6.25 IO 12.50 (0.150 to 0.500) O\C~ 12.50 to 25.00 (0.500 to 1.00) 01 er 25.00 to 37 50 t I Ml to I .SO) mcr 37.501050 00 ( I .so to 2.001 o\cr50.00 to67.50(‘00 to 2.50) o\er62.50to7S.OOt2.5Oto3.0(Jt o\sr75.OOt3.001
Practice)
Minimum Atmosphere furnace min 20 25 45 60 75 90 I05 IN IL-J)
soaking
time Salt bath min I7 I8 3.5 JO 45 SO 55 60 (c,
(81 Thisknnrss 15 minimum dimrnslon of heaviest secuon of part or nested load of parts. th1725hpluilSmtnior~~rr) I~.5nm110.5tn.~or1ncrementofl2.Smm~0.Sin.)orer 7S mm (3 in.). (rrt I h. 5 minplus 5 mtn t’orc\rp 12.5 mm(0.S in.)orincwmentof 12.5 (0.5 in.ro\rr75 mm13 in.). Source: .AhlS 2759/-l
Austenitic
Stainless
Steels / 749
316N Chemical
Composition. AISI/UNS (S31651): 0.08 c. 2.00 hln. 1.00 Si. 16.00 to 18.00 Cr. 10.00 to I-1.00 Ni. O.O-IS P. 0.03 S. 2.00 to 3.00 MO. 0. IO to 0. I6 N
Similar
Steels (U.S. and/or Foreign). AShlE SA I 82. S.42 I 3. SAXO. SA249. SA312. SA358. S.4376. SA103. SA130. SA-179: ASThl A 182. A2 13. AZ-IO. AX9. A276. .43 12. A35X. A376. A-103. A130. A179
Characteristics. affecting
ductility
Has added nitrogen. which increases strength M ithout and corrosion resistance
Forging.
Start forging at I IS0 to I260 “C (?I00 to 2300 “F). Do not forge after forging stock drops belo\r 92.5 “C t I695 “F). Cool to black color in less than 3 min. using liquid quench if nscess;u)
Recommended Normalizing.
Heat Treating
Do not normalize
Practice
Annealing. Anneal at 1010 to I I20 “C (1850 to 2050 “F). To guard against drstortion of thin. delicate parts. leave ample room for expansion between parts. Stainless grades clpand about twice as much as carbon and IOU -allo> steels. Allow enough time for through heatmg after thermocouple has reached temperature. Stamless Fades have approsimatel> half the thsrmal conducti\ it! of c‘arbon and low-alloy steels. Choice of atmosphere depends on finish desired and whether surfacs stock will be removed. For bright annealing. use vacuum or an atmosphere of hydrogen or dissociated ammonia at de\\ point of -62 to -74 C (-80 to -100 “F). Parts must be thoroughly clean and drl. Inert gases argon and helium (although expensi\ e) and nitrogen. with dew points of less than -51 “C (-65 “F), can be used. The! lack the reducmp effect of hydrogen, so slight discoloration in the form of chrome oxide can result. Salt. sxothermic. or endothermic atmospheres are satisfactor) for nonbright annealing. Salt is difficult to remove. and rinse quenching at 595 ,‘C’ I I105 “F) is not recommended. because inwrruptrd quench at elevated temperature cannot be tolerated. Exothermic and endothermic atmospheres must be arcfully controlled at
750 / Heat Treaters
Guide
equivalent carbon potential to avoid carburiration. which will seriously lower corrosion resistance. Same problem with atmosphere annealing. If oxidizing conditions are present, scale will form. Dificult to remove in subsequent descaling operations. Cool rapidly from annealing temperature: no more than 3 min to black color. Section size determines quenching medium: water for heavy sections, air blast for intermediate sizes, and still air for thin sections. Carbides can precipitate at gram boundaries when parts are cooled too slowly between 425 IO 900 “C (795 to 1650 “F). In aerospace practice, parts are annealed at a set temperature of 1095 “C (2000 “FJ and quenched in air. oil. polymer, or water. Sections over 6.25 mm (0.25 in.) thick should be water quenched to minimize distortion. Parts fabricated horn steel in a strain-hardened condition should not be annealed. stress relieved, or dimensionally stabilized without permission of the cognizant engineering authority. Heat treating or slow cooling of unstabilized grades between 470 to 815 “C (875 to IS00 “F) is prohibited, except for 304L and 3 I6L. See table for soaking times
adequate at 525 to 550 “C (975 to 1020 ‘T) for 20 to 48 h (depending on case depth required). Dissociation rates for single-stage cycle are from 20 to 35%. Hardness is as high as 1000 to 1350 HK on surface. 48-h cycle produces case extending to 0.127 mm (0.005 in.) with approximately 800 to 1000 HK. Case will rapidly drop to 200 HK core hardness, at approximately 0. I65 mm (0.0065 in.)
Recommended l l l l l l
Processing
Cold work Anneal and quench Remove surface contamination Stress relieve Depassivate (if nitriding) Nitride (if required)
316N:
Soaking
(if required)
Times (Aerospace
%%?SS Rl?ikViflg. Parts can be relieved after quenching to achieve dimensional stability, by heating to 230 to 400 “C (US to 750 T) for up to several hours. depending on section size and without change in metallographic structure
Diameter or thickness(a) of maximum section mm (in.) inclusive
Nitriding.
“pt02.50~0.100) over 2.50 to6 25 (0. IO0 to0.250,
Not recommended. Case seriously impairs corrosion resistance in most media. Case seldom more than 0. I27 mm (0.005 in.) deep. Only used in specialized applications where material must be nonmagnetic and have wear-resistant surface. If nitrided. parts must be in annealed condition to prevent flaking or blistering of nitrided case. All sharp comers should be replaced with radii of not less than I .59 mm (0.06 in.). Film of primarily chromium oxide. that protects stainless alloys from oxidation and corrosion, must be removed prior to nitriding. Accomplished by wet blasting, pickling, chemical reduction in reducing atmosphere, submersion in molten salt. or by one of several proprietary processes, If doubt exists that complete and uniform depassivation has occurred, further reduction of the oxide may be accomplished in furnace by means of reducing hydrogen atmosphere or suitable proprietary agent. After depassivation, avoid contamination of surface by finger or hand marking. Single-stage nitriding
Sequence
o\er 6 !S to I1 50 (0 Xl to 0.500) 3\5r I2 50 co 15.00 10.500 to 1.00) over 25.00 to 37.50 (I 00 to 1.50) over 37.50 to 50.00 ( I..50 to 2.00) over SO.00 to 62.50 (2.00 to 2.50) over6250 to 75.00 12.50 to 3 00) over 75.00(3.00)
Practice)
Minimum soaking time(b) Atmosphere furnace Salt bath min min 40 1s
37
65 80 9.5 II0 I25 l-l0 (c)
55 60 65 70 75 80 (d)
38
(q) Thickness is minimum dimension of heaviest section of part or nested loadofpans. (h) Parts should be held for sufficient time to ensure that center of most massive section has reached tetI$WaN~ and necessary transformation and diffusion have taken place. (c)lh,35minplus 15minforevery 1~.5mm(0.50in.)orincrementof12.50mm(0.50 in.) over 75.0 mm (3 in.). (d) I h. 2S min plus 5 min for every 12.50 mm (0.50 in.) or increment of 12.5 nun (0.50 in.) over 75.0 mm (3 in.). Source: AMS 2759/4
750 / Heat Treaters
Guide
316LN Chemical
COmpOSitiOn. AISI/UNS: 0.03 C, 2.00 Mn, 1.00 Si. 16.00 to 18.00 Cr. 10.00 to 11.00 Ni. 0.015 P. 0.035 S. 3.00 to 3.00 MO. O.lOto0.l6N
Recommended
Heat Treating
Practice
Annealing.
In aerospace practice, parts are annealed at a set temperature of 1095 “C (2005 “F) and quenched in water uith one exception: parts under 2.5 mm (0. IO in.) thick may be air cooled or polymer quenched to minimize distortion. Parts fabricated from steel in a strain-hardened condition. such as t/z hard. shall not be annealed. stress relieved. or dimensionally stabilized without permission of the cognizant engineering authority. Also, heat treating or slow cooling unstabilized grades between 370 to 815 “C (875 to I500 “F) is prohibited, except for 3ML and 3 I6L. See table for soaking times Stress Rehhlg. In aerospace practice. parts are stress relieved at 900 “C (1650 “F), and quenched in water. As an alternative. parts may be stress relieved at annealing temperatures. Sections under 2.5 mm (0. IO in.) thick may be air cooled to minimize distortion. Parts fabricated from steel in the strain-hardened condition. such as h hard, shall not be stress relieved without permission of the cognizant engineering authority. When stress relieving after welding, hold for 30 min minimum at the stress relieving temperature. Heat treating or slow cooling of unstabilized grades between
470 to 815 “C (875 to 1500 “F) is prohibited, See table for soaking times
316LN:
Soaking
Times (Aerospace
Diameter or thickness(a) of maximum 5ection mm (in.) inclusive over ‘.SO to6.3 rO.100 to0.250) o\cr 6 75 to 12.50 (0.250 to 0300) o\er I2 50 to 25.00 (0.500 to I .OO)
o\er 25.00 to 37.50 ( I .w to I .SO) over 37.50 to SO.00I I .SOto 2.00) overSO.Wto62.SOt2.Wto2.SO) over 62.SO to 75.00 (2 50 to 3 00) over 7SWt3 00)
except for 304L and 316L.
Practice)
hlinimum soaking time@) Atmosphere furnace Salt bath min min 40 45 65 80 9s I IO 13 I-20 (C)
37 38 55 60 6S 70 75 80 W
(a) Thickness is minimum dimenston of heaviest section of part or nested load of parts. I ht Parts should be held for sufficient time to ensure that center of most massive section has reached temperatute and necessary transformation and diffusion have taken place. (c)2 h. 35 min plus I5 mm forevery 12.5 mmtO.SOin.)orinctementof 12.SOtnm(O.S0 in.) over 75.0 mm t3 in.). (d) I h. 25 nun plus 5 mm for every 12.50 mm (0.50 in.) or incrcmentof 12.SmmtO.SOin.)o~er7S.Ommt3in.).Soutce: AMS275914
Austenitic
Stainless
Steels / 751
317 Chemical
Composition.
AlSI/UNS
I .OO Si. 18.00 to 20.00 Cr. Il.00
(S31700): 0.08 c. 2.00 hln. to 15.00 Ni. 0.0-15 P. 0.03 S, 3.00 to 1.00
MO
Similar Steels (U.S. and/or Foreign). ASME sA2-10. sA2-W. SA312. SAd03. SAaOY; ASTM A167. A2-W. A269. A276. A312. A3 I-l, A103. A309, A473. AJ78, AS I I. A5S-l. ASgO. A632; FED QQ-S-763; MIL SPEC MLS-862; SAE 5305; Ger.) DIN I.-U-l9; (Ital.) UNI X 5 CrNihlo I8 15: (lap.) JIS SUS 317 Characteristics. plications.
especially
Exhibits excellent corrosion resistance where pitting corrosion is a problem
in special ap-
Forging.
Start forging at I IS0 to 1260 “C (2100 to 2300 “FL Do not forge after forging stock drops helow 925 “C t 1695 “F). Cool to black color in less than 3 min. using liquid quench if necessary
Recommended Normalizing. Annealing.
Heat Treating
Practice
Do not nomtalize
Anneal at 1010 to I I20 “C (I850 to 2050 “FL To guard against distortion of thin. delicate parts. leave ample room for expansion hetueen parts. Stainless grades expand about twice as much as carbon and low-alloy steels. Allow enough time for through heating after themrocouple has reached temperature. Stainless grades have approximately half the thermal conductivity of carbon and low-alloy steels. Choice of atmosphere depends on ftnish desired and whether surface stock will be removed. For bright annealing. use vacuum or an atmosphere of hydrogen or dissociated ammonia at dew point of -62 to -7-l “C t-80 to -100 “F). Parts must be thoroughly clean and dry. Inert gases argon and helium (although expensive) and nitrogen. with dew points of less than -5-l “C (-65 “F). can be used. They lack the reducing effect of hydrogen. so slight discoloration m the form of chrome oxide can result. Salt. exothermic. or endothermic atmospheres are satisfactory for nonbright annealing. Salt is difftcult to remove, and rinse quenching at 595 “C i I105 “F) is not recommended. because interrupted quench at elevated temperature cannot be tolerated Exothermic and endothermic atmospheres must be carefully controlled at equivalent carbon potential to avoid carburization. which will seriously lower corrosion resistance. Same problem uith atmosphere annealing. If oxidizing conditions are present. scale aill form. Diflicult to remove in suhsequent descaling operations.
Cool rapidly from annealing temperature: no more than 3 min to black color. Section size determines quenching medium: water for heavy sections. air blast for intermediate sizes. and still air for thin sections. Carbides can precipitate at grain houndaries u hen parts are cooled too slowly between -I25 to 900 “C (795 to 1650 “F) Stress RekVing. Parts can he relieved aher quenching to achieve dimensional stability, by heating to 230 to -IO0 “C (US to 750 “F) for up to several hours. depending on sectton size and without change in metallographic structure
Nitriding. Not recommended. Case seriously impairs corrosion resistance in most media. Case seldom more than 0.127 mm tO.005 in.) deep. Only used in specialized applieattons u here material must be nonmagnetic and hate Hear-resistant surface. If nittided. parts must be in annealed condition to prevent flaking or blistering of nitrided case. All sharp comers should be replaced H ith radii of not less than I .59 mm (0.06 in.). Film of primarily chromium oxide. that protects stainless alloys from oxidation and corrosion. must he removed prior to nitriding. Accomplished by wet blasting. pickling. chemical reduction in reducing atmosphere. submersion in molten salt. or by one of several proprietary processes. If doubt exists that complete and uniform dcpasstvation has occurred. further reduction of the oside may be accomplished in furnace by means of reducing hydrogen atmosphere or suitable propnetary agent. After depassivatton. avoid contamination of surface by linger or hand marking. Single-stage nitriding adequate at 525 to 550 ‘C (975 to 1020 “F) for 20 to G3 h (depending on case depth requtred). Dissoctation rates for single-stage cycle are from 20 to 35%. Hardness is as high as 1000 to I350 HK on surface. 48-h cycle produces case extending to 0. I27 mm tO.005 in.) with approximately 800 to 1000 HK. Case v+ill rapidly drop to 200 HK core hardness. at approximately 0. I65 mm (0.006.5 in. )
Recommended l l l l l l
Processing
Cold viork Anneal and quench Remo\ e surface contamination Stress relic\ e Drpassivate (if nitriding) Nitride (if required)
Sequence
t if requued)
Austenitic
Stainless
Steels / 751
317L Chemical
Composition.
1.00 Si. 18.00 to 20.00 Cr. II.00 h40
Similar
AIsI/UNS (S31703): 0.03 C. 2.00 hln. to 15.00 Ni. 0.045 P. 0.03 S. 3.00 to 1.00
Steels (U.S. and/or Foreign).
AWE
Al67.A24O;(Ger.)DIN l.-l43X:(Fr.)AFNOR22CND 2367: (U.K.) B.S. 317 S I2
SA240:
ASThl
19.S;(Swed.)SS1.4
Characteristics.
Similar to type 3 17. except more resistant to intergranular corrosion after belding or stress relieving. Recommended for parts which are fabricated by welding and cannot be subsequently annealed. Generally limited to service temperatures up to 425 “C (795 “F)
Forging. Start forging at 1230 “C (2245 “F). Do not forge after forging stock drops below 925 “C ( I695 “F)
Recommended Normalizing.
Heat Treating
Do not nomlalizc
Practice
Annealing.
Anneal at IO-10 to I IO5 ‘T I 1905 to 3025 OF). Use IO-IO “C (I905 ‘F) minimum for maximum ductility. Parrs can be air cooled from annealing temperature. IValer quenching not necessary. Slow cooling can occur through the 8 IS IO 12.5 “C ( I SO0 to 795 “F) range for up to 2 h. without subsequent danger of susceptibility IO mtergranular corrosion in natural atmospheric environmems
Stabilizing. Because type 3 I7L contains molybdenum. it is susceptible to sigma-phase formation as a resulr of long exposure at 650 to 870 “C ( 1200 to 1600 “F). Corrosion resistance improved by employing a stabilizing treatmen (ASThl A262C). consisting of holding at 885 “C ( 1625 “F) for 2 h prior to stress relieving a~ 675 “C ( I XS “F) Nitriding. Rare. Not recommended. Case seriously impairs corrosion resistance in mosl media. Case seldom more than 0.127 mm (O.OOS in.) deep. Only used in specialized applications where material must be nonmapnelic and have itear-resistant surface. If nitrided. parts must be in annealed condition to prevent flakinp or blistering of nitrided case. All sharp comers should he replaced \i ith radii of not less than I .S9 mm (0.06
752 / Heat Treaters
Guide
in. J. Film of pnmarily chromium oxide. that prorects stainless alloys from osidatron and corrosion. must be removed prior to nitriding Accomplished by met blasting. pickling. chemical reduction in reducing atmosphere. submersion in molten sah, or by one of several proprietary processes. If doubt elists that complete and unifomi depassivation has occurred. funher reduction of Ihe oxide may be accomplished in furnace by means of reducing hydrogen atmosphere or suitable proprietary agent. After depassivation. avoid contamination of surface by finger or hand marking. Sinplcstage nitriding adequate at 575 to 550 “C (975 to 1020 “Fr for 20 IO 48 h (depending on case depth required). Dissociation rates for single-stage cycle are from 20 to 3%. Hardness is as high as 1000 10 1350 HK on
surface. 48-h cycle produces case extending to 0. I27 mm (0.005 in.) with approximately 800 10 1000 HK. Case mill rapidly drop to 200 HK core hardness. at approsimately 0. I65 mm (0.0065 in.)
Recommended l l l l l
Processing
Cold work Anneal and cool Stabilize and stres5 relieve Dcpassivate (if niniding) Nitride (if required,
(if necessary)
Sequence
752 / Heat Treaters Guide
321 Chemical Composition. l.OOSi. 17.00to
AISI/UNS (S32100): 0.08 C. 2.00 hin. 19.00Cr. 9.0010 12.00 Ni. 0.015 P 0.03 S, 5 x Ci-CTi min
Similar Steels (U.S. and/or Foreign). AhlS 55 IO,
%t?SS Relieving. In aerospace practice. parts are stress relieved at 900 “C I 1650 “F). then quenched in air. polymer. or water. When stress relieving after irclding. parts are held 30 n-tin minimum at the annealing temperature. or 2 h minimum at the stress relieving temperature (see table for soaking times). Sections over 6.25 mm (0.25 in.) thick should be water quenched to minimtze carhide precipitation. Heat treating or slou cooling of unstabilized grades between -I70 to 8 I.5 “C (875 to I500 “F) is prohihited. ewept for 3O-lL and 3 I6L
5557. 5559.
5570. SS76.564S. 5689: ASME SA 182. SA 193. SA 19.4. SA2 13. SA2-w. SA2-l’). SA? 12. SA320. SA358, SA376. SA-tO3. SA-109. SA-l?O. SA-179: ASThl Al67. Al83.Al93. AI’)-&. A213. A240. A249. A269. A27l. A276. r\3 12. A3 14. A320. A358. A376. A103. A409. .A430. A473. A-179. A-193. AS I I: FED QQ-S-763. QQ-S-766. QQ-b’-123: hlIL SPEC MIL-S-86’: SAEU05(3132l);(Ger.)DfN l.-lS-Il;(Fr.)AFNORZ6CNTl8.lO:(Ital.) UNlX6CrNiTi I8 Il.X6CrNiTi I8 II KGXhCrNiTi I8 II KH’.Xb CrNiTi I8 I I KT. ICL 472 T: (Jap.) JIS SDS 321; (S~sd.) SStq 2337; (l!.K.,B.S.CDS-20.321 S 12.321 S 18.321 S22.321 S27.321 S-10.321 S49.321 SSO.321 SS9.371 S87.En.58C
Characteristics.
Stabilized hl the addition of titanium. this grade is near11 immune to intergranular precipitation of chromium carhide and its adverse effect on corrosion resistance. Recommended for parts which u ill he fabrtcated b> uelding and cannot be subsequsntl~ annealed. Rscommended for use between 125 to 900 “C (795 to I650 “F). Not recommended for decorative use. Hardenable by cold uork onI!. To impart maxmum corrosion resistance. use a stabilizing anneal in addition to annealing and stress relieving
Forging.
Start forging at I I.50 to I260 “C (2 IO0 to 2300 “FI. Do not forge after forging stoch drops belo\\ 925 “C ( I695 “F)
Recommended Normalizing. Annealing.
Heat Treating
Practice
Do not nomlalize
Anneal at 955 to I I20 “C I 1750 to 2050 “F) to relieve stresses. increase softness and ductility. or to pro\ ide additional stabiliration. See comments on protecttvc atmospheres for nnneality for bpe 201. Does not require water quenching To ensure maximum retention of austenite. oil or eater quench sections thicker than 6.-t mm (0.25 in.). In aerospace practice. parts are annealed at 980 “C i I795 “FJ and quenched in air. oil. polymer or mater. Sections over 6.25 mm (02.5 in.) thick should he water quenched to minimize distortion. Parts fabricated from steel in a strain-hardened condition. such as ‘,+ hard, shall not be annealed. stress relieved. or dimensionally stahilized without pemtission of the cognizant rngineerinp authority. See table for soaking times
Stabilizing. For maximum corrosion resistance. use corrective stabihzmp anneal by holding at 815 to 900 “C ( IS55 to 1650 “F) up to 5 h. depending on section thickness. Process applied hefore or during fabncation. hla) be followed hy stress relic\ ing at 705 “C (1300 “F) for a short time without harmful carhide precipitation Nitriding. Qptional. Not recommended. Case seriously impairs corrosion resistance in most media. Case seldom more than 0. I27 mm (0.005 in.) deep. OnI) used in specialized applications where materiaJ must be nonmagnetic and have itear-resistant surface. If nittided, parts must be in annealed condition to pre\ent flaking or blistering of nitrided case. All sharp comers should be replaced with radii of not less than I S9 mm (0.06 In.). Film ofprimaril) chromium aside. that protects stainless alloys from oxidation and corroston. must he removed prior to nitriding. Accomplished hy wet blasting, pickling. chemical reduction in reducing atmosphere. submersion in molten salt. or hy one of several proprietary processes. If do&t exists that complete and uniform depasstvation has occurred. further reduction of the wide ma! be accomplished in furnace by means of reducing hydrogen atmosphere or suitable proprietary agent. After depassiv ation. avoid contammation of surface by finger or hand marking. Singlestage nitridinp adequate at S25 to 550 “C (975 to 1020 “F) for 20 to 48 h (depending on case depth required). Dissociation rates for smgle-stage cycle are from 20 to 35%. Hardness is as high as 1000 to 1350 HK on surface. 48-h cycle produces case extending to 0.127 mm (0.005 in.) with approximate11 800 to 1000 HK. Case vvill rapidly drop to 200 HK core hardness. at approximately 0. I65 mm (0.0065 in.) Recommended l l l l l
Processing
Cold moork Anneal and cool Stabilize and stress relieve Depassivate (if nitriding) Nitride (if necessag)
(optional)
Sequence
Austenitic 321:
Soaking Times (Aerospace Practice)
Diameter or thickness(a) of maximum section mm (in.) inclusive up to 2 50 (0.100) o\er?.SO to63 (0.100 to 0.30) oivr 6.25 to 12.50 (0.150 to 0.500) Ok’lx 12 50 to 25.00 10.500 to 1.00) o\er 25.00 to 37.50( 1.00 to 1.50) over 37.50 10 so.00 ( 150 10 2.00, o\erSO.OO to62.SO(XO to X0) over62SOto7SOO~2.SO1o3.00~ 0ver75.00(3.00)
Minimum soaking time(b) Atmosphere furnace Salt bath min mill 37 38 55 60 65 70 7s 80 (d)
(a) Thickness is minimum dimension of heaviest section of part or nested load of part, (h I Pxtnj should be held for suftkient ttme IO ensure thar center of most massi\ e section has reached tcntpertture and necessary transformation and diffitsion hn\e taken place. (c)2h.3Srntnplus ISminforeben 12.5mm(0.50in.)ormcrcmentof12.50nmm~0.S0 in.) over 75.0 mm (3 in.). (d) I h. ?S min plus 5 min for e\ew I?..50 mm 10.50 in.) or increment of 12.5 mm (0.50 in.) over 75.0 mm 13 in. I. Source ‘AhlS 2759/-l
Stainless Steels / 753
Austenitic
Stainless
Times (Aerospace
Practice)
Steels / 753
321 H Chemical l.OOSi.
Composition.
17.OOto
19.00Cr.9.OOto
Recommended
UNS 632109): 12.00Ni.0.045
Heat Treating
0.04
to 0.10
c.
7.00
P.O.03 S.S x GCTi
hln.
min
Practice
Annealing. In aerospace practice. parts are annealed at 980 “C I I795 “F) and quenched in air. oil, polymer. or uatcr. Sections over 6.3-S mm (0.25 in.) thick should he water quenched to minimize carhide precipitation. In stress relieving after welding. parts are held 30 min minimum at the annealing temperature, or 2 h minimum at the stress relieving temperature (see table for holding times). Parts fabricated from steel in a strain-hardened condition. such as I./? hard. shall not be annealed. stress relieved. or dimensionally stabilized uithout permission of the cognizant engineering authority Stress Relieving. In aerospace practice. parts are stress relieved at 900 “C (I650 “F). and quenched in air. polymer. or water. When stress relies mg after welding, hold for 30 min minimum at the annealing temperature or 7 h minimum at the wess relieving temperature (see table for soaking times). Sections over 6.25 mm iO.25 in.) thick should he water quenched to minimize carbide precipitation. Heat treating or slog cooling of unstabilized grades between 470 to 8 IS “C (875 to IS00 “F) $ prohibited. except for 304L and 3 l6L.
321 H:
Soaking
Diameter or thickness(a) of ma.simum section mm (in.) ioclusi\e
o\cr 2.SO106.25 (0.100 to0 250) o\er 6.15 IO 12.50 (0.250 IO 0.500) “\‘TT I?. 50 IO 25 00 10.500 to I 001 o\er 2.S 00 to 37 SO 1 I .oO 10 1.50, 0, er 37 SO to SO.00 I I SO 10 2.00) o\er5000to62.S0(2.00to2501 o\er62.SOro75 00~2.SO103.00~ o\er 7S.oO~3.OO~
Minimum soaking Atmosphere furnace min -lo -Is 65 80 95 II0 l2.i I-10 (c‘)
time@) Salt bath min 37 38 9s 60 6S 70 7S 80 Id)
la I Thickness is minimum dimensmn of hea\ irst wction of pun or nested load of pats. I bl Par& Jhould be held for sutiicient time mensure tharcrnvrofmosr massivesection has reached wmpsrature and nrcrssq rransformarion and diffusion hu\e taken place 1c1~h.3SrmnpluilSn~infor~~~n 12.5n~~O50in.~orincr~men~of1~.50mm~0.50 In.) wer 7S 0 mm t3 in.). I~I I h ?S nun plui 5 min for r\ery 12.SOmm (0.50 in.) or insremenr of I1 5 mm (0 SO m. I o\ er 75.0 mm (3 in. 1. Source. Ah% 275911
Austenitic
Chemical Composition.
AISl/UNS (S32900): 0. IO C. X0 hln. I .OO Si. 25.00 to 30.00 Cr. 3.00 to 6.00 Ni. 0.045 P, 0.03 S. I.00 to 2.00 hlo
Similar Steels (U.S. and/or Foreign).
AWE
SAX&
ASThl
A268. AS I I
Characteristics. Similar to tjpz 316. except exhibits superior rsGstance to stress corrosion cracking. Capable of agz hardening. but becomrs brittle if hardened and should be restricted to compressive forces in this condition. This is an austenitic-ferritic (duplex) stainless steel
Stainless Steels / 753
Forging. Start forging at 1095 ‘C tXO5 “FJ. Do not forge after forging stoch drops below 915 “C I I695 ‘FL Cool to black color in less than 3 min. using liquid quench if nssrss;lr) Recommended Normalizing. Do Annealing.
Heat Treating
Practice
not nomlulire
.Annal at 925 to 955 YY ! 1695 to I750 “FL Harden at 730 “C I I350 “FL Hold I7 h and cool rlo\r I> in air or furnace. To guard against distortion of thin, delicate pcxtb. leave ample room for expansion between part\ Stainless grxles expand about t\r ice as much as carbon and low-alloy
754 / Heat Treaters Guide steels. Allow enough time for through heating after thermocouple has reached temperature. Stainless grades have approximately half the thermal conductivity ofcarbon and low-alloy steels. Choice of atmosphere depends on finish desired and whether surface stock will be removed. For bright annealing. use vacuum or an atmosphere of hydrogen or dissociated ammonia at dew point of-62 to-74 “C (-80 to-100 “F). Parts must be thoroughly clean and dry. Inert gases argon and helium (although expensive) and nitrogen. with dew points of less than -54 “C (-65 “F), can be used. They lack the reducing effect of hydrogen, so slight discoloration in the form of chrome oxide can result. Salt. exothemtic, or endothermic atmospheres are satisfactory for nonbright annealing. Salt is difficult to remove. and rinse quenching at 595 “C (I I05 “F) is not recommended, because interrupted quench at elevated temperature cannot be tolerated. Exothermic and endothemtic atmospheres must be carefully controlled at equivalent carbon potential to avoid carburization. which will seriously lower corrosion resistance. Same problem with atmosphere annealing. If oxidizing conditions are present, scale will form. Difficult to remove in subsequent descafing operations. Cool rapidly from annealing temperature; no more than 3 nun to black color. Section size determines quenching medium: water for heavy sections, air blast for intermediate sizes, and still air for thin sections. Carbides can precipitate at grain boundaries when parts are cooled too slowly between 425 to 900 “C (795 to 1650 “F)
Nitriding. Not recommended. Case seriously impairs corrosion resistance in most media. Case seldom more than 0.127 mm (0.005 in.) deep. Only used in specialized applications where material must be nonmagnetic and have wear-resistant surface. If nitrided. parts must be in annealed condition to prevent flaking or blistering of nitrided case. AU sharp comers should be replaced with radii of not less than I.59 mm (0.06 in.). Film of primarily chromium oxide, that protects stainless alloys from oxidation and corrosion. must be removed prior to nitriding. Accomplished by wet blasting, pickling, chemical reduction in reducing atmosphere, submersion in molten salt. or by one of several proprietary processes. If doubt exists that complete and uniform depassivation has occurred, further reduction of the oxide may be accomplished in furnace by means of reducing hydrogen atmosphere or suitable proprietary agent. After depassivation. avoid contamination of surface by finger or hand marking. Single-stage nitriding adequate at 525 to 550 “C (975 to I020 “F) for 20 to 48 h (depending on case depth required). Dissoctation rates for single-stage cycle are from 20 to 35%. Hardness is as high as 1000 to 1350 HK on surface. 48-h cycle produces case extending to 0. I27 mm (O.OOS in.) with approximately 800 to 1000 HK. Case will rapidly drop to 200 HK core hardness, at approximately 0. I65 mm (0.0065 in.)
Recommended l l
Stress RelieVing. Parts can be relieved after quenching to achieve dimensional stability. by heating to 230 to 300 “C (-l-IS to 750 “F) for up to several hours. depending on section size and without change in metallographic structure
l l l l
Processing
Cold work Anneal and quench Remove surface contamination Stress relieve Depassivate (if nitriding) Nitride (if required)
Sequence
(if required)
754 / Heat Treaters
Guide
COmpOSitiOn. AISI/UNS (NO8330):0.08 C. 2.00 Mn.
Chemical
0.75 to I .50 Si. 17.00 to 20.00 Cr. 3-t.00 to 37.00 Ni, 0.040 l? 0.030 S
Similar
Steels (U.S. and/or
H31.3 I. H31.30: ASTM (30330). 5312 (30330)
Foreign).
B5 I I, BS 12. B535,
Characteristics. Has good resistance thermal shock. Magnetic in all conditions
MS B536.
5592, 57 16; ANSI B-516; SAE J-W.5
to carburization
and to heat and
Forging. Start forging at I I50 to I I75 “C (2 100 to 3 I SO “F). Do not forge after forging stock drops below 925 “C ( 1695 “F). Cool to black color in less than 3 min. using liquid quench if necessary
Recommended Normalizing.
Heat Treating
Practice
Do not normalize
remove, and rinse quenching at 595 “C (I IO.5 “F) is not recommended. because interrupted quench at elevated temperature cannot be tolerated. Exothermic and endothermic atmospheres must be carefully controlked at equivalent carbon potential to avoid carburization, which will seriously lower corrosion resistance. Same problem with atmosphere annealing. If oxidizing conditions are present. scale will form. Difftcult to remove in subsequent descaling operations. Cool rapidly from annealing temperature; no more than 3 mitt to black color. Section size determines quenching medium: water for heavy sections. air blast for intermediate sizes. and still air for thin sections. Carbides can precipitate at grain boundaries when parts are cooled too slowly between 425 to 900 “C (795 to 1650 “F) Stress Relieving. Parts can be relieved after quenching to achieve dimensional stability. by heating to 130 to 100 “C (44 to 750 “F) for up to several hours. depending on section size and without change in metallographic structure
Annealing.
Anneal at 1065 to I I75 “C (I950 to 2 I50 “F). To guard against distortion of thin. delicate parts. leave ample room for expansion between parts. Stainless grades rxpand about twice as much as carbon and low-ahoy steels. Allow enough time for through heating after thermocouple has reached temperature. Stainless grades have approximately half the thermal conductivity of carbon and low-alloy steels. Choice of atmosphere depends on finish desired and whether surface stock will be removed. For bright annealing. use vacuum or an atmosphere of hydrogen or dissociated ammonia at dew point of -62 to -74 “C (-80 to -100 “F). Parts must be thoroughly clean and dry. Inert gases argon and helium (although expensive) and nitrogen. with dew points of less than -5-t “C (-65 “F). can be used. They lack the reducing effect of hydrogen. so slight discoloration in the form of chrome oxide can result. Salt, exothermic. or endothermic atmospheres are satisfactory for nonbright annealing. Salt is difficult to
Nitriding. Not recommended. Case seriously impairs corrosion resistance in most media. Case seldom more than 0. I37 mm (0.005 in.) deep. Only used in specialized applications where material must be nonmagnetic and have wear-resistant surface. If nitrided. parts must be in annealed condition to prevent flaking or blistering of nittided case. AU sharp comers should be replaced with radii of not less than I.59 mm (0.06 in.). Film of primarily chromium oxide, that protects stainless alloys from oxidation and corrosion, must be removed prior to nitriding. Accomplished by wet blasting, pickling, chemical reduction in reducing atmosphere. submersion in molten salt. or by one of several proprietary processes. If doubt exists that complete and umform depassivation has occurred, further reduction of the oxide may be accomplished in furnace by means of reducing hydrogen atmosphere or suitable proprietary agent. After depassivation. avoid con-
Austenitic tanlination of surface by finger or hand marking. Single-stage nitriding adequate at 5X to 550 “C (975 to 1020 “F) for 20 to -18 h (depending on case depth required). Dissociation rates for single-stage cycle are from 20 to 35%. Hardness is as high as 1000 to 1350 HK on surface. 48-h cycle produces case extending to 0. I77 mm (0.005 in.) with approximately 1300 to 1000 HK. Case will rapidly drop to 200 HK core hardness. at approximately 0. I65 mm (0.0065 in.)
Recommended l l l l l l
Processing
Cold work Anneal and quench Remove surface contamination Stress relieve Depasstvate (if nitridinp) Nitride (if required)
Stainless
Sequence
(if required)
Steels I755
Austenitic
Stainless
Steels / 755
347 Chemical
Composition.
lOOSi. 17.OOto 19.00Cr.9.00ro +Tamin
AISI/UNS (S3J700): 0.08 C. 2.00 Mn. 13.OONi.0.045 P,O.O3OS, IO X %CNh
Similar Steels (U.S. and/or Foreign). ~1s 5s I 2, 5556, 5558, 5571. 5575, 5@6. 5654. 5674. 5680: ASME SAl83. SA193, SAl9-I. SA213. SA240. SA719. SA3 12. S.43’0. SA?58. S.4376. SA-103. S/-\-W. SAJ30. SAJ79; ASTM A 167. A 182, .4 193. A 194. A2 13. A2-19. A269. A271. A276. A3 13. A3 I-L A320. A358, A376, A-lO3. A-109. A-130, A-173. Ad79. Aa93. A5 I I. A554. AS80.4633: FED QQ-S-763, QQ-S-766. QQW-423; MLL SPEC MfL-S-862. MLL-S-23195, MIL-S-23196; SAE J-IOS t30317j; (Ger.) DfN 1.-15.50: (Fr.) AFNOR 26CNNb 18.10: (Ital.) LlNl X 8 CrNiNb I8 I I; (lap.) JIS SLIS 347: (Swed.) SSIJ 2338: (U.K.1 B.S. 347 S 17, En. 58 F. En. 58 G. ANC 3 Grade B Characteristics. Stabilized by the addition of niobium plus tantalum. this grade is nearly immune to intergranular precipitation of chromium carbide and its adverse effects on corrosion resistance. Thin sections do not require waler quenching from annealing temperature. Stabilizing anneal at 870 “C (I600 “F) seldom required. Hardenable by cold work only Forging. Starr forging at II50 to 1260 “C (2100 to 2300 “F). Do not forge after forging stock drops belo\\ 925 “C (I695 “F)
Nitriding. Optional. Not recommendsd. Case seriously Impairs corrosion resistance in most media. Case seldom more than 0. I27 mm (0.005 in.) deep. Only used in specialized applications where material must be nonmagnetic and have wear-resistant surface. If nitrided. parts must be in annealed condition to prevent flahing or blistering of nitrided case. AU sharp comers should be replaced with radii of not less than 1.59 mm (0.06 in.). Film of primaril) chromium oxide. that protects stainless alloys from oxidation and corrosion. must be removed prior 10 nitriding. Accomplished by wet blasting, pickling. chemical reduction in reducing atmosphere. submersion in molten salt. or b) one of several proprietary processes. If doubt exists that complete and uniform depassivalion has occurred. further reduction of the oxide may he accomplished in furnace by means of reducing hydrogen atmosphere or suitable proprietary agent. After depassivalion. avoid contamination of surface bq finger or hand marking. Singlestage nitriding adequate at 51-S to 550 “C (975 10 1020 “F) for 20 to 38 h (depending on case depth required). Dissociation rates for single-stage cycle are from 20 to 35%. Hardness is as high as 1000 to 1350 HK on surface. -18-h cycle produces case extending to 0. I27 mm (0.005 in.) with approximately 800 IO 1000 HK. Case will rapidly drop to 200 HK core hardness. at approximately 0. I65 mm (0.0065 in.)
Recommended l
Recommended Normalizing.
Heat Treating
Practice
Do not normalize
l l l
Processing
Sequence
Cold worh Anneal and cool Depassivate (if nitriding) Nitride (if necessary)
Annealing.
Anneal at 1010 to I I20 “C (I850 to 2050 “F). See recommended heat treating practice for type 201 for information on protective atmosphere for annealing. For thin sections. anneal to obtain maximum softness and ductility. Air cool. For sections over 6.25 mm (0.25 in. j. oil or water quench to ensure maximum retention of austenile. For titanium-stabilized type 32 I, a stabilizing anneal at approximately 870 “C ( 1600 “Fj is often used. Seldom used on niobium-stabilized grades. In aerospace practice. parts are annealed at IWO “C (I905 “F) then quenched in air. oil, polymer. or water. Seclions over 6.25 mm (0.25 in.) thick should be uater quenched to minimize carbide precipitation. Parts fabricated from steel in a strain-hardened condition. such as l/z hard. shall not be annealed. stress relieved. or dimensionally stabilized without permission of the cognizant engineering authority. See table for soaking times StrC?SS %?kViIlg. In aerospace practice. parts are suess relieved at 900 “C (1650 “F). As an alternative, this alloy may be stress relieved at annealing temperatures. Quenching is in air. polymer. or water. Sections over 6.25 mm (0.25 in.) thick should be water quenched to minimize carbide precipitation. Parts fabricated in the strain-hardened condition. such as ‘/z hard. shall not be suess relieved uithout permission of the cognizant engineering authority. See table for soaking times
347:
Soaking
Times (Aerospace
Diameter or thickness(a) of maximum section mm (in.) inclusive upro 2.SOtO 100) ovzr~.s0106.-?5~0.100100.2501 mer 6.25 to 12.50 f0 WI to 0.5001 over I30 IO 15 00 (0.500 to I .OOI over ~5.00 to 37 SO ( I .OO to I 501 over 37.50 to 50.M)’ I.50 to 2.ooJ o~erS0.00to6~.50~1lCIOto7-.SO~ o~er6250t07500t250to3.00t oser7S OO(3 001
Practice) hlinimum
Atmosphere furnace
soaking time(b) Salt bath
min
min
10 4s
37 38 5s 60 65 70 7s 80 w
65 80 9s II0 I’S IJO fCJ
raJ Th~kness 15 minimum dimension of hea\ iest section of part or nested load of parts. (ht Parts should be held for suflicient time to enwre that center of most massive section has reached temperature and nece>s+ transformatian and diffusion have taken place. tct2h.3SminolusISminfore\en I~.Stnm~0.50in.torincrementof12.50mm~0.50 in.) over 75 0 km 13 in.) (dr I h. ?S mm plus 5 min foreten 12.50 mm (0.50 ikor Increment of 12 5 mm (0.50 in.1 o\er 75.0 null t3 in.). Sourw’AMS 2759/J
756 / Heat Treaters
Guide
347H Chemical
Composition.
Mn. I .oO Si. 17.00 IO 19.00 min to I .OO max Nb
Recommended
AISI~I~NS (~4709): Cr. 9.00
to 13.00
Heat Treating
0.0-l
Ni. 0.045
to 0. IO C. xo
P. 0.030
S. 8 x 5C
Practice
347H:
Soaking
Times (Aerospace
Diameter or thickness(a) of maximum section mm (in.) inclusive
Annealing.
In aerospace practice. parts are annealed at 1040 “C ( I905 “F) then quenched in air. oil. pol!,rner. or Hater. Sections over 6.25 mm to.35 in.) thirk should he uater quenched to minimize carhide precipitation.. Parts fabricated from steel in a strain-hxdened condition. such as t+ hard. shall not be annealed. stress relieved. or dimensionall> stahilired without pemlisslon of the cognizant engmeering authorit>. See table for soaking times
Stress
f?etievirlg.
900 “C ( 1650 “F’L As annealing temperatures. o\er 6.75 mm tO.25 carbide precipitation. such as !+ hard. shall cognizant engineering
In aerospace practlcs. parts are stress relkrd at an altcmatke. this allo! may he stress relieved a~ Quenching IS in au. polymer. or uater. Sections in.) thick should be mater quenched to minimize Parts Fdbncntsd In the strain-hardened condition. not he stress relieved without pemussion of the authority. See table for soaking times
oker 2.501063 10 lOOro0.XJ~ over 6.3 to 12.50 10.150 to 0.5001 oker 12.50 10 25.00 (0.500 to 1.00) o\er 25 llOro 37.2Ot I 0010 1.5Ot o\er 37.5010 50.00~ lSO~ol.00~ o\er SO.00 to 62.50 I WQ to 2.50, over62 50ro75.OOt~.50to 3.001 o\sr75.OOl3001
Practice)
Minimum soaking Atmosphere furnace min 40 4s 65 80 95 I IQ I25 I-IO 15)
time(b) Salt bath min 37
38 55 Ml 65 70 75 80 Cd)
~a~l’hichness ii nlinimumdimcnsionofhea\icstsrclionofpanornestedloadofpans. I h) Pms should he held for sufticirnr time to ensure that center of most miLSs,ve section has reached temperarurr and necessary trunsformation and diffusion habe taken place. 1c,~h.3~minplu~ljnljnforr~r~ 12.~nim~i).50in.)orincremen~of12.50mm(0.50 in.) o\er 75.0 mm 13 in.,. Id) I h. 25 nun plus S nun forevery 12.50 mm (O.SO in.)or increment of 12.5 mm ~0.50 in.) oker 75.0 mm I 3 in.). Source. AMS 2759/4
756 / Heat Treaters
Guide
348 Chemical
Composition.
AISWNS
l.OOSi. 17.OOto lY.OflCr.S).(X)to ‘“rC min Nh. 0. IO Ta
(SMSOO): 0.08 c. XXI hln.
13.OONi.(J.015
P.O.03OS.O.2Co.
IOx
Similar Steels (U.S. and/or Foreign). AShlE SA 182. SARI 3. SAXO. S.4249, SA3 12. SA3SX. S.4376. S.4-!03. SA-IOY. SA-l7Y: hSThl .4167. Al82 A213. A2-lO. 44219. 4269. A’76. A.712 ,431-t. A358. A376. A403. A17Y. A580. A632; FED QQ-S-766: hllL SPEC hlJL-S-‘3195. ML-S-23196; SAE J3OS (30348): (Ger.) DIN l.Gl6: ~U.K.J B.S. 3-17 S 17. 3-l7 s 18. 317 s -to. 2 s. 130. s. 525. s. 527 Characteristics.
Similar
to gyps 3-17. exespt
tantahm~ content requanservice. Hardenable
stricted to 0. IO max and cobalt to 0.20 max. Used where restricted tity of these elements by cold work only
is required,
as in radioactive
Forging.
Start forging at I IS0 IO 1260 “C (2 100 IO 2300 “F). Do not forge after forgut@ stock drops below 925 “C i l6YS “F)
Recommended Normalizing. Annealing.
Heat Treating
Practice
Do not nomtnlire
Anneal al 1010 to I I20 ;C (I850 to 2050 ‘.Ft. See recommended heat treating practice for type 201 for information on protective atmosphere for annealing. For thin sections, anneal to obtain maximum softness and ductility. Air cool. For sections over 6.25 mm (0.25 in.). oil or mater quench to ensure maximum retention ofaustenits. For titanium-stabilized type 32 I. a stabilizing anneal at approximately 870 “C r 1600 “F) is often used. Seldom used on niobium-stabilized grades. In aerospace practice. parts are annealed at IO-IO ‘C ( 1905 “F) then quenched in air. oil. polymer. or water. Sections o\er 6.25 mm (0.25 in.) thick should be mater quenched to minimize carbide precipitation.. Parts fabricated from steel in a strain-hardened condition. such as ‘/: hard. shall not be annealed, stress relieved, or dimensionally stabilized without permission of the cognizant engineering authority. See table for soaking times
Stress RelieVing. In aerospace practice. parts are stress relieved at 900 “C (I650 “Ft. As an altematr\e. this ahoy may be stress relieved at annealing temperatures. Quenching is in air. polymer, or water. Sections o\er 6.25 mm (0.25 in.) thick should be water quenched to minimize carbide precipitation. Parts fabricated in the strain-hardened condition. such as t/2 hard. shall not be stress relieved uithout permission of the cognizant engineering authority. See table for soaking times
Nitriding. Optional. Not recommended. Case seriously impairs corrosion resistance in most media. Case seldom more than 0. I27 mm (0.005 in.) deep. Only used in specialized applications where material must be nonmagnetic and ha\e ear-resistant surface. If nitrided. parts must be in annealed condition to pre\cnt tlaking or blistering of nitrided case. All sharp comers should be replaced H ith radii of not less than I .S9 mm (0.06 in.). Film of primarily chromium oxide. that protects stainless alloys from oxidation and corrosion. must be removed prior to nitriding. Accomplished by \\et blasting. pickling. chemical reduction in reducing atmosphere. submersion in molten salt. or by one of several proprietary processes. If doubt exists that complete and uniform depassivation has occurred. further reduction of the oxide may be accomplished in furnace by means of reducing hydrogen atmosphere or suitable propnetary agent. After depassi\ ation. a\ oid contamination of surface by linger or hand marking. Singlestage nitriding adequate at S2S to 550 “C (975 to 1020 “F) for 20 to 48 h (dependin! on case depth required). Dissociation rates for single-stage cycle are Iron1 20 IO 35%. Hardness is as high as 1000 to 1350 HK on surface. 18-h cycle produces case extending to 0. I27 mm (0.005 in.) with approximately 800 to 1000 HK. Case \iill rapidly drop IO 200 HK core hardness. at approximately 0. I65 mm (0.0065 in.)
Recommended l l l l
Processing
Cold \soork Anneal and cool Depassb ate t if nitriding Nitride (if necessary)
r
Sequence
Austenitic
348:
Soaking Times (Aerospace
Diameteror thickness(a) of maximum section mm (in.) inclusive
o~erI.SOto6.~S(O.l00toO.?SO~ over 6.25 to 12.50 (0.250 to 0.500) over I I..50 to ‘5.00 (0.500 to I .OO) over 25.00 10 37.501 I Ml lo 1.50) over 37.50 to SO.00 ( I.50 to 2.00) over SO.00 IO 62.50 COO to 1.50) o~er62.SOto74.00(1.SOto3.TX)~ o\er75.00(3.00)
Practice)
i%linimum soaking Atmosphere furnace min -10 1s 6.5 80 95 II0 135 I10 (Cl
time(b) Salt bath min 37 38 55 60 65 70 75 80 (d)
la) Thickness is mmimum dimension of hen\. iest wction of pm or nesled load of parts I b) Parts should be held for suftkicnt time IO ensure (hat cenler of most massi\ e section has reached temperature and neceasq transformaCon and diffusion have taken place. (c)Z h.39 nin plus IS min foreven’ 12.5 nini~O.SOin.)orincremen~of 12.SOmm(O.S0 in.) over 750 mm (3 in.). id) I h. ?S nun plus 5 nun forrtery 12.50 mm (0.50 in.) or mcrement of 11.5 mm (0.50 in.)o\er 75 Omm (3 in.,. Sourw ALIS 1759/A
Stainless
Steels I757
Austenitic
Stainless
Times (Aerospace
Practice)
Steels I757
348H Chemical
Composition.
AISI~UNS (~34809): 0.04 to 0. IO c. xo
Mn. I .OO Si, 17.00 to 19.00 Cr. 9.00 to 13.00 Ni. 004.5 P, 0.030 S. 0.2 Co. 8 x CC min to I .OO max Nb. 0. IO Ta
Recommended
Heat Treating
Practice
348H:
Soaking
Diameter or thickness(a) of maximum section mm (in.) inclusive
Annealing.
tn aerospace practice. parts are annealed at 1040 ‘C ( 1905 “F) then quenched in air. oil, polymer. or &Cater. Sections over 6.3 mm to.25 in.) thick should be water quenched to minimize carbide precipitation.. Parts fabricated from steel in a strain-hardened condition. such as !+ hard. shall not be annealed. stress relie\cd. or dimensionall!, stabilized without permission of the cognizant engineering authority. See table for soaking times
Stress RelieVing. In aerospace practice. parts are stress relicLed at 900 “C (1650 “F). As an alternative. this allo) may be stress relieved at annealing temperatures. Quenching is in air. polymer. or mater. Sections over 6.3 mm (0.25 in.) thick should be water quenched to minimize carbide precipitation. Parts fabricated in the strain-hardened condition. such as ‘/2 hard. shall not be stress relieved without permission of the cognizant engineering authorit). See table for soaking times
o\rr2.SOto6.2St0.10C)to0.2S0) oter 6.25 IO 12.50 10.250 to 0.500’1 over 12.50 to IS 00 (0.500 to I .OO) o~rr~SWto37.S01I.~)Otol.S0~ over 37 so to so.00 ( I .so to 2.00~ over SO.00 toh3Ot~.OO to 2 501 okcr62 SOto75.00~2 SO IO 3.00) 0ver75.0013.001
(SJThi&;nr~f
Minimum soaking Atmosphere furnace min 40 -Is 65 X0 9s II0 125 I40 ICI
time(b) Salt batb min 37 38 5s 60 65 70 7s X0 IdJ
is minimum ilimen,ion of hen\ ieil wstion of part or nested load of parts. I h) Par~should he held forwfficirtnt time toenwre thatcrnterofmost massi\rsecdon ha reached temperature and newsal?. transformation and diffusion habe taken plscc tc~2h.3S minplus ISnunfore\en 12.5 mn110.SOin.,orinsrementof 12.50mm~0.50 tn.) over 7S.0 mm I 3 In ). td) I h. 15 mm plu> S nlin fur r\ery I250 mm (0.50 in.) or mcrrment of 12 S mm IO SO in bo\er 7S.0 mm (3 in 1. Sourw 4hlS 275914
Austenitic
Stainless
Steels I757
384 Chemical
Composition. AISI~NS (S38400): 0.08 C. 2.00 kin. 1.00 Si, IS.00 to 17.00 Cr. 17.00 to 19.00 Ni. 0.045 P. 0.030 S
Similar
Steels (U.S. and/or Foreign).
ASTM
~493;
SAE J405
(3038-l)
Characteristics.
Has a loher cold \+ork hardening rate than type 305. Used when severe cold heading or cold forming operations are required
Forging. Start forging at I IS0 to 11-30 ‘C 12100 to 224S “FL Do not forge after forging stock drops below 925 “C t 1695 “Fj. Cool to black color in less than 3 min. using liquid quench if nece\sq
Recommended Normalizing.
Heat Treating
Practice
Do not nomlalize
Annealing. .Annenl at IO-W to I I SO “C ( 190s to 2100 “F). To guard against distortion of thin. delicate parts. leave ample room for expansion hetueen parts. Stainless gades expand about tH ice as much as carbon and lo\\ -alloy steels. Allo\\ enough time for through heating after thermocouple has reached temperature. Stainless grades have approximately half the thermal conducti\ ib of carbon and lo\r-allo) steels. Choice of atmosphere depends on linish desired and \i hether surface stock nilI he removed. For bright annealing use vacuum or an atmosphere of hydrogen or dissociated ammonia at de\{ point of -62 to -71 “C t-80 to -100 “F). Parts must he
758 / Heat Treaters
Guide
thoroughI> clean and dr). Inert gases ;trgon and helium (although s\pensi\e) and nitrogen. \bith dr\r points of less than -S-l “C c--6S “F). can bc used. The) lath the reducing &‘a~ of hydrogen. so slight discoloration in the form of chrome o\ids can result Salt. cxothrrmic. or sndothsmic atmospheres are satisfactor) for nonhright ;Inncnling. Salt is diffialt to remove. and rinse quenching at 5% “C I I IOS “F) is not recommended. hecausrt interrupted quench at clr~ated temperature cannot hr tolerated. E\othrrmic and endothermic atmospheres must he carefully contmlkd at equib alent carbon potential to avoid carhuriration. u hich u ill ssriousl~ Iwer corrosion resistance. Same prohlsm with atmosphere annealing. if oxidizing conditions are prebrnt. wale itill form. Difficult to remove in suhscquent dcscnling operations. Cool rapidly from annealing temperature: no more than 3 min IQ hlack color. Section SIX dstemunes quenching medium: water for hew! SWtions. air blast for intamediatr sires. and btill atr for thin bsctions. Cnrhidrs cm precipitate at grnrn houndark I\ hen parts are cooled too slou I> hstwssn 425 to Wo “C (7Y5 to I650 “FI Strt?.SS RdieVing. Parts ran he relkrd after qusnshing. to nchwc dimensionul Stabilit). h! hentmg to 2.30 to -IO0 :‘C (US to 750 ‘F) for up tv weral hours. depending WI section 4ze and \rithout chanffe in mrtallographic struucturs
Nitriding.
Not recommended. Case srriou4y impair5 corroston resistance in most media. Case seldom more than 0. I27 mm (0.005 In.) deep. OnI! uwd in ~pccialired application\ \\ here mutsrinl must he nonmnpnetlc and hats wctr-resistant wrface. If nittided. parts must he in ~nnsaled
condition to pre\ent Flaking or hli>terinp ofnitridrd case. All sharp comers should he replawd M ith radii of not Icsb than I .SY mm (0.06 in.). Film of primaril> chromium oxide. that protects jtainkss alloys from oxidation and corroGon. must he rsmo\cd prior to nitriding. Accomplished by wet blasting. pickling chemical reduction in reducing atmosphere. suhmersion in molten salt. or hv one of wa-al propriety processes. If doubt exists that complete and uniform depassi\ ntion has occurred. further reduction of the oxide may he accomplibhrd in furnace hy mean5 of reducing hydrogen atmosphere or suitable propriety ngcnt. After depassiwtion. avoid contamination of surface by finger or hand marking. Single-stage nitriding adequate at 52.5 IO MO “C 1975 to 1020 “F) for 20 to 18 h (depending on case depth requtrsd). Dissociation rates for single-stage cycle are from 20 to 35%. Hardness is as high as 1000 to I350 HK on surface. 1X-h cycle produces GIST extending to 0. I27 mm tO.005 in.) with approximatel) 800 to 1000 HK. Cast \\ill rapid11 drop to 200 HK core hardness. ;II approximately 0.165 mm (0.0065 in.)
Recommended
Processing
Cold work . .Annsal and quench l Remo\s surface contamin;ttion . Stress relk? l Dcpajsl\ate cif nitriding, l Nitride iif required)
Sequence
l
rif required)
Ferritic
Stainless
Steels
Introduction The ferritic stainless steels remain ferritic at all temperatures, theoretically. and thus they are not allotropic and cannot be hardened by heating and quenching. However, this is not always completely true. Some ferritic steels are borderline to the extent that if the chromium is on the low side and the carbon is on the high side some transformation to austenite can take place on heating. This. in turn. can transform to martensite upon cooling. The extent to which this takes place. however, is not usually of great practical significance. Therefore, the principal heat treatment applied to the fenitic grades is annealing, which is usually achieved by rapid cooling from elevated temperature. In their annealed condition. ferritic stainless steels develop maximum softness. ductility. and corrosion resistance. Annealing serves primarily to relieve stresses resulting from welding or cold working. Secondarily, it provides a more nearly homogeneous structure by eliminating patches of transformation product developed during welding or as a result of 475 “C (885 “F) embrittlement. Ferritic steels usually are annealed at temperatures abobe the range for 375 “C (885 “F) embrittlement and below temperatures at which austenitr might form. The table included in this section summarizes current annealing practices for the ferritic grades. Even ferritic grades can retain austenite or untempered martensite from partial transformation to austenite at high temperatures. Aluminum has been added to type 405 to eliminate or minimize austenite formation and decomposition during welding. When fusion welding heats this grade above 1095 “C (2000 “F). embrittlrment may still result. This is corrected by a subsequent heat treatment at 650 to 8 I5 “C ( I200 to IS00 “0. When type 430 is cooled rapidlq from above 925 “C ( I700 “F). it may become brittle from austenite transforming to as much as 30%, martensite. The austenite may be retained, if it is cooled rapidly from temperatures much above 1095 “C (2000 “F). This may be corrected by heating to 760 to81S°C(1400to 1500°F). A form of brittleness peculiar to the ferritic grades can develop from prolonged exposure to. or slow cooling within. the temperature range from about 400 to 525 “C (750 to 975 “F). with a maximum effect variousI) asserted as occurring at 470,475. or -I80 “C (875. 885. or 900 “F). Notch impact strength is most adversely affected. The brittleness is believed to be caused by precipitation of a high-chromium ferrite. Its effects increase rapidly with chromium content, reaching a maximum in type 446. Certain heat treatments. such as furnace cooling for maximum ductility, must be controlled to avoid embrittlement. The brittle condition can be eliminated by any of the treatments listed in the table. using temperatures clearly above the upper boundary of embrittlement. followed by rapid cooling to prevent a recurrence.
Annealing Treatments of Ferritic Stainless Steels Temperature(s) OF 405 4439 429 430 13OF 43OFSe 43-1 136 -I42 446
1350to I500 1625 to l-450 to I400 IO 125010 1250 to I-150 to I-150 to 1350 to l-150 to
1650 1550 I 500 1400 1300 1550 1550 I500 1600
“C
COOliflg method(b)
735 to815 885 IO 900 790 to 845 760 to815 615 to 760 675 to 760 790 10 815 790 to 815 73SlO815 790 to 870
AC or WQ AC AC or WQ AC or WQ AC or WQ AC or WQ AC or WQ AC or WQ AC or WQ AC or WQ
(a~ Time at lemprrature depends on section rhichncss. but is usually I LO2 h. ewepr for sheet which ma! be soaked 3 to 5 min per 2.5 mm (0. IO in J of tickness. (b) AC. air cool: H’Q. ua~erquench
Sigma phase is a crysrallographic constituent that forms slowly at elevated temperatures in straight-chromium steels containing more than about 164 Cr and in chromium-nickel steels containing more than about 18% Cr. Sigma phase increases hardness, which is sometimes useful, but it decreases ductility, notch toughness. and corrosion resistance. The lower temperature limit for its formation depends exponentially on exposure time. For practical purposes. it can be placed near 540 “C (1000 “F). The upper boundary varies with alloy content. Nitriding. In general. the ierritic grades are more easily nitrided than are the austenitic grades. Somen hat deeper cases can be formed on the ferritic grades. using the same practice as used for the austenitic steels described in this Volume. Just as it is true for the austenitic grades. nitriding also impairs corrosion resistance of the ferritic grades. so that applications for nitrided ferritic stainless steels are limited. Forging. For the most part. the allowable forging temperature range for these steels is fairly broad. restricted somewhat at high temperature because of grain growth and structural weakness. Type 305 is the only one of this group for which finishing temperature is closely restricted. This is because this specific grade develops grain boundary weakness caused by debelopmem of small amounts of austenite. Other ferritic grades are commonly finished at temperatures as low as 760 “C (1400 “0. For forging of type -146. the linal IOQ, reduction is preferably made below 870 “C (1600 “F) to achieve grain refinement and room temperature ductility. Forgings of ferritic steels should always be annealed.
760 / Heat Treaters
Guide
405 Chemical
Composition.
AISI~UNS
(~~0500): 0.08 C. 1.00 bJn.
I .OO Si. I 150 to 14.50 Cr. O.WO P. 0.030 S. 0. IO to 0.30 Al
Similar
without significant hardenmg. Not susceptible welding. Ductile. Easily machined
to hardening
cracks during
Steels (U.S. and/or Foreign). AShlE SAUO. SAz68. SM79: ASTM A 176. A2-10. A268.276. A3 I-l. A473. A-)79. AS I I. AS80: FED QQ-S-763: hlfL SPEC hlIL-S-862; SAE J-W iSl-105): (Ger.) DIN l.-tOO?; (Fr.) AFNOR Z 6 CA 13: (1tal.r 1iNl X 6 CrAl 13: (Jap.) JIS SDS -lOS: (U.K.) BS 405 S I7
Forging. Start forging at 1065 to I I20 “C (1950 to 2050 “F). Finish at 870 to 925 “C ( I600 to I695 “F,
Characteristics. Nonhardenahls grade fi here air-hardening tjpes such as 1 IO or -IO3 are objectionable. Can he cooled from elevated temperatures
Annealing. Low anneal remperatures to I SO0 “F). Air cool or water quench
Recommended
Heat Treating
Practice range from 735 to 8 I5 “C ( I355
760 / Heat Treaters
Guide
409 Chemical
COIIIpOSitiOn. AISI/UNS (SJO900): 0.08 C, 1.00 hln. 1.00 Si. 0.50 Ni. 0.045 F! 0.045 S. IO.50 UJ I I .7S Cr. 6 x W min. 0.75 Ti mnx
Similar
Steels (U.S. and/or Foreign).
Al76. A268. A6Sl: !3E.i40S 409: (U.K.) B.S. 409 S I7
(51409~
t&r.,
AShlE SA268: ,ASThl DfN 1.4512: (J~D.) I JIS SLlH
Characteristics. A general purpose construction steel. Intended for application5 u here appearance is secondary to mechamcal and corrosion resistance properties
Recommended Annealing.
Annealing I650 “F). Air cool
Heat Treating temperatures
Practice
range from 885 to 900 “C (I625 to
760 / Heat Treaters
Guide
429 Chemical
Composition. AISIfilNS (s42!300): I.00 Si, I-LOO 11) 16.00 Cr. 0.040 P. 0.030 S
Similar
Steels (U.S. and/or
Foreign).
SA?-68: ASThl .A 176. A 182. X40. A26X. X76. ASS4: FED QQ-S-763. QQ-S-766. QQ-M’-43; SAE J-105 (5 1129)
Characteristics. ueldnbilit~ than tjpr f~\ation equipment
0. I 2 c.
I .oo MO.
ASME SA I x2. SAUO. A3 I -I. A473, A-193. A5 I I. hlk SPEC hlLL-S-863:
This corrosion and heat resisting steel has better 430. Applications include nitric acid and nitrogen
Forging. Start forging at IO-10 to II?0 he as low as 760 T I I400 “F)
Recommended Annealing.
Heat Treating
Temperatures Air cool or water quench
“C ( 1905 to X.50 “F). Finish can
Practice
range from 790 fo 845 “C (1450 fo I550 “F).
760 / Heat Treaters
Guide
430 Chemical
Composition.
AISI/UNS
(S.UOOO): 0. I 2 C. I .OO tvln.
Characteristics.
Gsnsral purpose. nonhardenahle chromium-type and heat resistance properties are superior to 110
I.00 Si. 16.00 to 18.00 Cr. 0.04 P. 0.03 S
lo). Corrosion
Similar
Forging. Start forging at 1040 to I I20 “C (I905 760 10 8 I5 “C ( I400 to IS00 “F)
Steels (U.S. and/or Foreign).
AhIS 5503. 5627: ASME SA 182. SA’40. SA268. SA-179: ASTM A 176. .A 182. ?-\210. A768. A776. 431-I. A473. A479. A-193, ASI I, A55-1. AS80. A65 I: FED QQ-S-763, QQ-S-766. QQ-S-423. STD-66: hlIL SPEC hllL-S-862; SAE J-&OS tSl-l30):(Ger.1DW I.4Olh:(Fr.)AFNORZ8C 17;(Ital.) lJNlX8Cr 17; (Jap.) JIS SUS 130: (Swed.) SSIJ 2320: (U.K.) B.S. 430 S IS
Recommended Annealing. Xnnralinp
Heat Treating
al-
to 2050 “F). Finish at
Practice
Parts are annealed at 760 to 815 “C ( I-100 IO IS00 OF). should b? follo\\ed by Ltater quenching or very rapid cooling
Ferritic
Stainless
Steels / 761
430: Hardness vs Tempering Temperature. Composition: C,0.33Mn,0.020S.0.019P. l.OOSi. 16.96Cr.Barheated400h. Source: Allegheny Ludlum Industries
0.07
Ferritic
Stainless
Steels / 761
430F Chemical
Composition.
AISI/UNS
(S43020): 0. I7 C. I.15 hln.
Forging.
I .OO Si. 16.00 to 18.00 Cr. 0.06 P. 0.15 S nun. 0.6 hlo (optional)
St&art forging at IO65 to I I50 jC ( 1950 to 2 100 “F). Finish at 760to815”C(I400to 1500°F)
Similar
Recommended
Steels (U.S. and/or Foreign). ASTM A314 AS81. ASK?; MIL SPEC Ma-S-862 SAE 1405 (Sl330F): (Ger.) DIN 1.1104: (Fr.) AFNOR Z IO CF 17; (Ital.) CINI X IO CrS 17; tJap.) JIS SUS 130 F: (Swed.) SSt4 2383 Characteristics. Suitable
Free-machining variation for use on automatic screw machmes
of 430 for heavier
cuts.
Annealing. quench
Heat Treating
Practice
Anneal at 675 to 760 “C ( IUS to l-100 “F). Air cool or water
Ferritic
Stainless
Steels / 761
430FSe Chemical
Composition.
AlSI/UNs (S43023): 0.12 C. 1.25 hln.
I .OO Si. 16.00 to IX.00 Cr. 0.06 P. 0.06 S. 0. IS SC min
Similar
Steels (U.S. and/or
AS81. A%?:
MlL SPEC hlfL-S-862:
Foreign).
ASThl
.A? 14.
~473.
SAE J-105 (5 I430FSe)
Characteristics. Free-machining variation of 130 for lighter cuts. Suitable for use in automatic screw machines nttainsd by sclsnium additions
Forging. Start forging at 1065 to I IS0 “C (1950 to 2100 “F). Finish at 760to815”C~14IOto lSOO”F)
Recommended Annealing. u ;Iter quench
Heat Treating
Tempsmture
Practice
is 675 to 760 “C i 17-15 IO 1100 “F). Air cool or
Ferritic
Stainless
Steels / 761
434 1.00 Si. 16.00 to 18.00 Cr. O.-l P. 0.3 S. 0.75 to I.15 hlo
Forging. Start forging at 1040 to I I20 “C (I905 to 2050 “F). Finish can he xi IOU ;1~ 760 “‘C t I-100 “F,
Similar
Recommended
Chemical
Composition.
AI.Sl/UNS
(S43400): 0. I2 C. I .(I0 hln.
Steels (U.S. and/or Foreign). ASTM A65 I; SAE J-105 (51431); (Ger.) DIN I.41 13; (Fr.) AFNOR Z 8 CD 17.01; tltal.) l!NI X 8 Crhlo 17; (lap.) JIS SUS 33-l; (Sued.) SSIA 33; (U.K.) B.S. 13-l S I9 Characteristics. Designed for use as automotke sion because of \rmter road conditioning
trim to resist corro-
Annealing. quench
Heat Treating
Practice
Anneal at 790 to 845 “C t I.455 to IS55 “F). Air cool or water
762 / Heat Treaters
Guide
436 Chemical
Composition. AISI/UNS (S43600): 0.13 C. 1.00 hln. I .OO Si, 16.00 fo 18.00 Cr, 0.04 P, 0.03 S. 0.75 to I.25 MO. 5 X ‘XC min to 0.70 max Nb + Ta Similar
Steels (U.S. and/or
Characteristics. applications. Similar “ridging” is required
Foreign).
SAE J405 (51436)
Adaptable for general corrosion and heat resisting to types 430 and 43-l. Used where low “roping” or
Forging.
Start forging at 1065 to I I20 “C (1950 to 2050 “F). Finish can be as low as 870 to 925 “C ( I600 to I695 “F)
Recommended Annealing. water quench
Heat Treating
Temperature
Practice
is 790 to 835 “C (I455 to 1555 “F). Air cool or
762 / Heat Treaters
Guide
439 Composition. AISl/UNS (S43035):0.07 C. 1.00 Mn. 1.OO Si, 0.50 Ni, 17.00 to 19.00 Cr. 0.04 P, 0.03 S, 0.15 Al, 12 X o/X min
Chemical to l.lOTi
Characteristics.
Recommended Annealing. water quench
A low interstitial
grade
Annealing
Heat Treating
Practice
is at 870 to 925 “C (I600 to 1695 OF). Air cool or
762 / Heat Treaters
Guide
442 Chemical
Composition.
AISI/UNS
(S44200): 0.20 C. 1.00 hln.
I .OO Si. 18.00 to 33.00 Cr. 0.0-l l? 0.03 S
Similar
Steels (U.S. and/Or
Foreign).
ASTM
A 176; SAE J4Os
(51442)
Characteristics.
Used mainly for parts which must resist scaling at high temperatures. Maximum temperature resistance is 980 “C ( 1795 “F) or 1040 “C f 1905 “F) for intermirtent use
Forging. Start forging al 870 to I 150 “C (1600 to 2 100 OF). Fish he as low as 760 “C ( I400 “F)
Recommended Annealing. water quench
can
Heat Treating Practice
Temperature
is 735 to 8 I5 “C ( I355 to 1500 “F). Air cool or
762 / Heat Treaters Guide
446 Chemical Composition.
AISIjUNS
(S44600): Nominal. 0.20 C.
1.50 Mn. 1.00 Si. 23.00 to 27.00 Cr. 0.040 P 0.030 S. 0.25 N
tures. Withstands destructive scaling up to 1095 “C (2005 OF). Often used in sulfur-bearing atmospheres
Similar Steels (U.S. and/or Foreign).
Forging. Suut forging at 1065 to I I20 “C (I950 can be done as IOU as 760 “C ( 1400 “F)
Characteristics.
Recommended Heat Treating Practice Annealina. Anneal at 790 to 870 “C ( 1455 to 1600 “FL
ASME ~~268; ASTM A 176. A268, A276. A3 14, A173. A5 I I. A580; FED QQ-S-763. QQ-S-766: MfL SPEC MlL-S-862: SAE J-IO5 (5 1446)
Has the maximum amount of chromium of ferritic stainless steels. Used for parts which must resist scaling at high tempera-
quenching
to 2050 “F). Finishing
Air cool or water
-
446: Hardness vs Tempering Temperature. Bar heated 400 h. Source: Allegheny
Ludlum Industries
Martensitic
Stainless
Steels
Introduction The martensitic stainless steels represent one portion of the 400 Series of stainless steels. The remainder consists of the fenitic steels. which cannot be heat treated for hardening. The heat treating of the martensitic stainless steels is essentially the same as that for carbon and low-alloy steels. Their potential for developing maximum strength and hardness depends primarily on carbon content. The principal metallurgical difference is the high alloy content of the stainless grades. This causes the transformation to martensite to be sluggish and the hardenability to be high. For these reasons, maximum hardness is produced by air cooling in the center of sections approximately 305 mm (I 3 in.) thick. Chromium is the principal alloying element in these steels. The martensitic stainless steels are more sensitive to heat treating variables than are carbon and low-alloy steels. Therefore, rejection rates because of faults in heat treating are correspondingly high. Because of the initial high cost of these stainless steels and the cost of processing them into parts, there is no advantage in using them unless superior corrosion resistance is required. Consequently, the hardening procedures discussed in this section are limited to those that preserve corrosion resistance. To avoid contamination, all parts and heat treating fixtures must be cleaned completely before they are placed in the furnace. Racks and fixtures should be made of stainless steel or one of several nickel-base alloys containing appreciable amounts of chromium, such as the lnconel alloys. Proper cleaning is particularly important when the heat treatment is to be performed in a protective atmosphere. Martensitic stainless steels are normally hardened by being heated above the transformation range to temperatures of 935 to 1065 “C ( I695 to 1950 “F) and cooled in air. Because of the poor tbemlal conductivity of stainless steels. high thermal gradients and high stresses during rapid heating may cause warping or cracking in some parts. To avoid these problems, preheating is usually recommended before annealing or hardening, especially for thin-gage parts, parts with both thin and thick sections, parts with sharp comers and re-entrant angles. heavily ground parts, parts machined with deep cuts, parts that have been cold formed or straightened. and previously hardened parts that are being reheat treated. Preheating is normally accomplished at 760 to 790 “C ( 1400 to 1455 “F), and heating
need be continued only long enough to ensure that all portions of each part have reached the preheating temperature. Types 403.4 13. and 4 I6 require less preheating than the higher carbon stainless steels, such as 430 and 440. When maximum corrosion resistance and strength are desired. these steels should be austenitized at the high end of the temperature range. For alloys that are to be tempered above 565 “C (I050 “F), the low side of the austenitizing range is recommended. because it enhances ductility and impact properties. Soaking times represent a compromise between (a) achieving maximum solution of chromium-iron carbides for maximum strength and corrosion resistance and (b) avoiding decarburization. excessive grain growth. retained austenite. brittleness. and quench cracking. Because of their high hardenability. all martensitic stainless steels can be quenched in either oil or air. Oil quenching guarantees maximum corrosion resistance and ductility in all alloys. Air quenching may cause some decrease m ductility and corrosion resistance in types 4 14.420.43 I, and 440. These steels may precipitate carbides at grain boundaries. if heavy sections are cooled slowly through the temperature range of approximately 870 to 540 “C (I 600 to 1000 “F). The higher carbon steels, such as 44OC. and the higher nickel -131 are likely to retain large amounts of untransformed austenite in the as-quenched structure, frequently as much as 30% by volume. A portion of the retained austenite may be transformed by subzero cooling (stabilizing), followed by tempering. For Fully hardened steels. increasing degrees of recovery toward the annealed condition are given by (a) stress relieving. (h) tempering, (c) subcritical annealing, and (d) full annealing. The martensitic stainless steels are sometimes nitrided to increase surface hardness and wear resistance and to achieve a lower coefficient of friction. In aerospace practice. austenitizing in atmospheres containing hydrogen is limited to parts to be tempered above 540 “C (1000 “F). Annealing in hydrogen-containing atmospheres is permuted. Atmospheres containing nitrogen at 980 “C ( I800 “F) and higher are not permitted when parts have finished machined surfaces. Endothermic and carbon-containing, nitrogenbase atmospheres are prohibited in treating 13 I or any alloy to 1240 MPa (180 ksi) or higher.
403 Chemical Composition. AISIjUNS (!%0300):0.15 C, I .OObin, 0.50Si, I I .50 to 13.00 Cr. 0.04 P, 0.03 S Similar Steels (U.S. and/or Foreign).
AMS 561 I, 5612; ASTM A 176. A276. A3 14, A473. A479. A508, A5 I I ; FED QQ-S-763; MILSPEC MJL-S-862; SAE J-IO5 (51403); (Ger.) DIN 1.402-l: (Jap.) JIS SUS 303. SUS 416; (U.K.) B.S. 420 S 29, En. 56 B
Characteristics. Special quality grade used for turbine blades and similar applications. Otherwise comparable to type 410. May be quenched in oil or air. Can be martempered. Capable of hardening to 42 HRC or slightly higher. Can be tempered to provide a wide range of strength and impact resistance. Extremely deep hardening. Maximum hardness obtained
by air quenching sections up to approximately 305 mm (I2 in.) thick. Can be full. process, or cycle annealed. Good corrosion resistance. Susceptible to stress corrosion cracking in corrosive environments, when stress is above threshold level for that particular environment. Magnetic in all conditions. Fair machinability. Resists oxidation up to 8 I5 “C ( I500 “F)
Forging.
Start forging at 1095 to 1205 “C (2005 to 2200 “F). Do not forge after temperature of forging stock drops below 870 to 925 “C ( I600 to 1695 “F)
Recommended Normalizing.
Heat Treating
Do not normalize
Practice
764 / Heat Treaters
Annealing. l
l
l
Guide
Can be process. isothermal.
or full annealed:
Process c~nneal in subcritical temperature range of 650 to 760 “C ( I100 to I-KKI “F). Llse clean. rectified salt bath or an atmosphere that is compatible with this temperature range. Soaking time dependent on SIZZ of work. Air cool. Hardness. 86 IO 92 HRB Isorhermol nrrrwul by heating at 830 to 885 “C ( I525 to 1625 “F). Cool slowly to 705 “C (1300 “F). Hold for 6 h. Hardness, approximately 85 HRB FM// annrc~l at 8 IS to 900 “C ( 1500 to 1650 “F). Cool slowly to 595 “C (I I05 “F) at a rate not to exceed I7 to 22 “C (30 to -IO “F) per h. After this. cooling rate has no effect on hardness. Avoid carburization or decarburization. Can use atmospheric protectlon in the form of a \acuum, the inert gases argon or helium (both expsnsive). or nitrogen. All should have dew point belo\{ -5 I “C t-60 “F). Eriothermic- or endothermic-generated atmospheres can be used, providing carbon potential of the gas matches carbon content of the steel. Hardness. 75 to 85 HRB. Full annealing is expensive and time consuming. Should not be used. except as required for subsequent severe foming or difficult machining
In aerospace practice. parts are annealed at 845 ‘C (I555 “F) and austenitized at 980 “C ( 1795 “F). then quenched in oil or polymer. Cooling in air or other gases is permitted for parts less than 6.25 mm (0.250 in.) in maximum thickness proi’ided the) are not racked or densely packed. In annealing, parts are cooled to below 595 “C t I IO5 “F) at a rate not IO exceed 30 “C (55 “F) per h, Followed b) air cooling to ambient. An austenitizing temperature of 955 “C (I750 “Fj is permitted for thin sections to minimize warpage
Hardening.
Atmospheric protection rules for annealing appll to hardening. Parts must be completely clean and free of oil and shop contamination. Thermal conductivit) is significantly loueer than that of carbon and alloy steels. High thermal gradients and hlph stresses during rapid heating ma) cause warpage and cracking in delicate or intricate parts. Preheat at 760 to 790 “C (I 400 to l-155 “F). only long enough to equalize temperature in all sections. Extremely delicate or intricate parts \tould benefit from an additional prior preheat of S-10 “C (I000 “F). Austenitized at 925 IO 1010 “C ( 1695 to I850 “F). Llse upper end of range for larger sections or H hen maximum corrosion resistance and strength are required. If tempering temperature exceeds 565 “C (I050 “F), use IOU side of the austenitizmp
403: Isothermal Transformation
Diagram. Composition: 0.15 C max, 1 .OO Mn max, 0.040 P max, 0.030 S max, 0.05 Si max, 11.50 to 13.00 Cr. Austenitized at 980 “C (1795 “F). As-quenched hardness. 41 HRC
range. It enhances ductilit) and impact resistance. Soaking time of 30 to 60 min is adequate for sections up to I3 mm (0.50 in.). Allow an additional 30 min for each additional inch or fraction thereof. Double soaking time if parts have been full or isothermal annealed. Increase time by 50%. if process annealed for long periods above 705 “C ( I300 “F). Quench in oil or air. Oil quenching preferred. because it guarantees maximum corrosion resistance and ductility. hlartempering in hot oil or salt is practicable because of high hardenability. As-quenched hardness, approximately 375 10415 HB
Stabilizing. Optional. To transform essentially all retained austenite. use stabilizing or subzero treatment of -76 to -195 “C (-105 to -320 “F). Temper immediately to temper the new martensite to avoid cracking Tempering.
Temper at 205 to 760 “C (400 to I400 “F). Temper at 705 to 370 “C t-IO0 to 700 “F) for hardness approximately 38 to 45 HRC. Temper at 565 IO 605 “C ( 1050 to I I75 “F) for hardness approximately 25 to 3 I HRC. Tempering at 370 to 650 “C (700 to I200 “F) not recommended for parts requiring high toughness and optimum corrosion resistance. Causes a marked dip in impact resistance and lowered stress corrosion cracking resistance. Double tempering beneticial. Cool to room temperature between tempers
Nitriding. Can be nitrided to case depth of approximately in 18 h. See type -IlO for further information
Recommended l l l l l l l l l l l l
Processing
0.103 mm (0.008 in.)
Sequence
Forge Anneal Rough machine Stress relieve Finish machine Preheat Austenilize Quench Stabilize (optional) Temper Final grind to size Nitride (if required)
403: Hardness vs Tempering Temperature. Composition: 0.10 to0.115C,0.30to0.45Mn,0.014to0.018P,0.012Smax,0.28to 0.45 Si, 12.18 to 12.34 Cr, 0.34 to 0.63 Ni, 0.02 to 0.08 MO. Heat treated at 1010 “C (1850 “F), ‘;2 h. Oil quenched: 66 to 94 “C (150 to 200 “F). Double stress relieved at 175 “C (345 “F), 15 min. Water quenched. Tempered 2 h. Heat treated, 14 mm (0.550 in.) round. Tested, 12.8 mm (0.505 in.) round. Source: Republic Steel
Martensitic
403:
Soak Time for Annealing
and Austenititing
(Aerospace
mm
Up105 St0 I5 IStO
25 IO40 4Oto50 50 to 65 65 10 75 15 IO 90 9010 loo loot0 Il.5 1151011. 125 t07-00 Over 20
In.
b
Up IO0.250 -_ to 0.500 Over O.‘W OwrO.SOO to I .OOO O\er I .OOOto I .SOO Over I .SOO to 2.000 Over 2.OOO to 2.500 Over 2SOO to 3.000 Over 3.0 to 3.SOO O\er 3.500 to-LOW Ober 4.000 to -1.SM) Over 4.500 to S.000 Over 5 BOO to 8 000 Over 8 000
Minimum time(b)
min
hours
soak salt min I8 35 40 45 SO 55
25 -Is I I I I 2 2 2 2 3 ? (Cl
Steels / 765
Practice)
hlinimum soak time(b) air or atmosphere
Thickness(a)
Stainless
IS 30 -IS IS 30 -IS
I I I I
S IO IS
,O
I I
‘0 -IO
td)
(a)Thickness is the minimum dimension of the heaviest section of the part tb) Soaking shall commence N hen all control. indicating. and recording thermocouples reach the specitied set temperature, or if load thermocouples are used, uhsn the part temperature reaches the minimum of the furnace uniformity tolerance at the set temperature. Parts coated B ith copper plate or similar reflective coatings that tend to reflect radiant heat shall have their soaking time increased by at least SO0‘0, unless load thermocouples are used. When load thermocouples arc used. the soaking time shall be not less than 30 rnmutes. In all cases, the parts shall be held for sufticwnt time to ensure that the center of the most massive area has reached temperature and the necessary transformauon and diffusion have taken place. hlaximum soak time shall be nvw the minimum specified, except for subcritical .mnraling. Longer times may be necessary for parts wnh complex shapes or parts that \\on’t heat uniformly. (c)-l h plus 30 mm for s~cry 75 mm (3 in.), or portion thereofgreater than 200 mm (8 in.). (d) 2 h plus 20 mm for every 75 mm (3 in.). or portion thereof grealer than 200 mm (8 in.). Source: AMS 2759’5
403: Partial Isothermal Transformation
Diagram. Modified turbine grade. Composition: 0.074 C, 0.39 Mn, 0.034 P, 0.010 S, 0.27 Si, 0.30 Ni, 12.22 Cr, 0.52 MO, 0.039 N. Austenitized at 1065 “C (1950 “F). Grain size: 6 to 8
403: Hardness vs Tempering Temperature. Composition: 0.115 C, 0.45 Mn, 0.014 P, 0.012 S, 0.45 Si, 12.18Cr, 0.63 Ni, 0.08 MO. Heat treated at 925 “C (1695 “F), l/z h. Oil quenched: 66 to 94 “C (150 to 200 “F). Double stress relieved at 175 “C (345 “F), 15 mm. Water quenched. Tempered 1 h. Heat treated, 14 mm (0.550 in.) round. Tested, 12.8 mm (0.505 in.) round. Source: Republic Steel
Martensitic
Stainless
Steels / 765
410 Chemical
Composition.
~rsr/l!NS (!GlOOO):0. I5
C. I .OO hln.
I .OO Si, II .SO to 13.50 Cr. 0.W P, 0.03 S
Similar
Steels (U.S. and/or
Foreign).
ALIS 550-I. 5405. 5591.
5613. 5776, 5821; ASME S4194 (6). SAWO. SA268. SA-+79: ASThl A176.A193,A19~.A2-t0,A376.A?I-l,A173.A-179. MY?. A5ll.AS80; FED QQ-S-763. QQ-W-r23: hllL SPEC hIIL-S-862; WE J-IO.‘, (51-110). JJlZ~514lO):tGer.)DIN l.1006:(Fr.~AFNORZ IOC 13.Z IOC 1-l.Z I2 C 13;(Ital.)UNIX I?Cr 13.X IOCr 13,X IZCr I3 KG.X l2Cr 13KKH’: (Jap.) JIS SUS -IlO; (Sued.) SS.14 2302: (U.K.) B.S. -IlO S 21. En. 56 A. ANC I Grade A. 3 S. 61. S. I41
Characteristics.
General purpose. heat treatable stainless steel. Corrosion resistant and heat resistant. Capahls of hardening to 42 HRC or slightI!
higher. Can he tempered to \\ ids range of strength and impact resistance. Can be quenched in oil or air. Oil quenching guarantees maximum corrosion resistance. Hiph alloy content causes sluggish transfomration and high hardenability. For these reasons. maximum hardness is obtainable by air quencJ.krg in the center of sections up to approximately 305 mm (I 2 in.) thick. Can be martempered with ease. Can be titll. process. or isothermal annealed. Has good corrosion resistance. Susceptible to stress corrosion cracking in corrosive em ironment~. when stress is above threshold level for that particular environment. hlapttc in all conditions. Fair machinahilitj. Resists oxidation up to 8 I5 “C t IS00 “F)
Forging.
Snut forging at IO95 to 120s “C t2OOS to 2200 “F). Do not forge after tempernture of forging stock drops below 870 to 925 “C t 1600 to 1695 “F)
766 / Heat Treaters
Recommended Normalizing. Annealing. l
l
l
Guide
Heat Treating
Practice
Do not normalize Can be process, isothermal.
or full annealed:
Process onneal in subcritical temperature range of 650 to 760 “C t I200 to 1400 “F). Use clean. rectified salt bath or an atmosphere that IS compatible with this temperature range. Soaking time dependent on size of work. Air cool. Hardness, 86 to 92 HRB Isorhetmal anneul by heating at 830 to 885 “C (I 525 to I625 “F). Cool slowly to 705 “C (1300 “F). Hold for 6 h. Hardness, approximately 85 HRB Full cmwal at 830 to 885 “C ( I525 to I625 “F). Cool slowly to 595 “C (I IO5 “F) at a rate not to exceed I7 to 22 “C (30 to 10 “F) per h. After this. cooling rate has no effect on hardness. Avoid carburization or decarburization. Can use atmospheric protection in the form of a vacuum, the inert gases argon or helium (both expensive). or nitrogen. All should have dew point below -5 I “C (-60 “F). Exothermic- or endothermic-generated atmospheres can be used, providing carbon potential of the gas matches carbon content of the steel. Annealed hardness, 75 to 85 HRB. Full annealing is expensive and time consuming. Should not be used. except as required for subsequent severe forming
In aerospace practice. parts are annealed at 845 “C ( I555 OF’) and austenitized at 980 “C ( 1795 “F), then quenched in oil or polymer. Cooling in air or other gases is permitted for parts less than 6.25 mm (0.250 in.) in maximum thickness, provided they are not racked or densely packed. In annealing. parts are cooled to below 595 “C ( I IO5 “F) at a rate not to exceed 30 “C (55 “F) per h. followed by air cooling to ambient. An austenitizing temperature of 955 “C ( 1750 “F’) is permitted for thin sections to minimize watpage
Hardening. Atmospheric protection rules for annealing apply to hardening. Parts must be completely clean and free of oil and shop contamination. Thermal conductivity is significantly lower than that of carbon and alloy steels. High thermal gradients and high stresses during rapid heating may cause warpage and cracking m delicate or intricate parts. Preheat at 760 to 790 “C (I400 to 1455 ‘F). only long enough to equalize temperature in all sections. Extremely delicate or intricate parts would benefit from an additional pnor preheat of 540 “C (I000 “F). Austenitized at 925 to 1010 “C (I 695 to I850 ‘F). Use upper end of range for larger sections or when maximum corrosion resistance and strength are required. If tempering temperature exceeds 565 “C (1050 “F), use low side of the austenitizing range. It enhances ductility and impact resistance. Soaking time of 30 to 60 min is adequate for sections up to I3 mm (0.50 in.). Allo& an additional 30 mm for each additional inch or fraction thereof. Double soaking time if parts have been full or isothermal annealed. Increase time by 50%, if process annealed for long periods above 675 “C ( I245 “F). Quench in oil or air. Oil quenching preferred, because it guarantees maximum corrosion
resistance and ductility. Martempering in hot oil or salt is practicable because of high hardenability. As-quenched hardness, approximately 375 to 415 HB
Stabilizing. To transform essentially all retained austenite, use stabilizing or subzero treatment of -76 to -195 “C (-105 to -320 “F). Temper immediately to temper the new martensite to avoid cracking Tempering.
Temper at 205 to 705 “C (400 to I300 “F). Temper at 205 to 370 “C (400 to 700 “F) for hardness approximately 38 to 47 HRC. Temper at 565 to 605 “C ( 1050 to I I25 “F) for hardness approximately 25 to 3 I HRC. Tempering at 370 to 565 “C (700 to I050 “F) not recommended for parts requiring high toughness and optimum corrosion resistance. Causes a marked dip in impact resistance and lowered stress corrosion cracking resistance. Double tempering beneficial. Cool to room temperature between tempers
Nitriding. Not recommended for severe corrosive environment. Nihided case impairs resistance to corrosion in most media. Maximum case obtainable is about 0.203 mm (0.008 in.) in 48 h. Before nitriding. parts should be quenched and tempered. uith tempering at least I4 “C (25 “F) higher than the nitriding temperature. All sharp comers should be replaced with radii of not less than I.588 mm (0.06 in.). The ftlm of oxide that protects stainless alloys from oxidation and corrosion must be removed. This may be accomplished by wet blasting, pickling. chemical reduction in a reducing atmosphere. submersion in molten salts. or by one of several proprietary processes. If doubt exists that complete and uniform depassivation has occurred. further reduction of the oxide may be accomplished in a furnace by reducing hydrogen atmosphere or suitable proprietary agent. After depassivation. avoid contamination of surface by linger or hand marking. Single-stage nitriding usually adequate at 525 to 550 “C (975 to 1020 “F) for 20 to 48 h. depending on case depth required. Hardness above 1000 HK can be expected for several thousandths of an inch before hardness gradient blends into core
Recommended l l l l l l l l l l l l
Processing
Forge Anneal Rough machine Stress relieve Finish machine Preheat Austenitize Quench Stabilize (optional) Temper Final grind to size Nitride (if required)
410: End-Quench
Hardenability
Sequence
Martensitic
Stainless
Steels
/ 767
410: Isothermal Transformation Diagram. Composition: 0.11 C, 0.44 Mn, 0.37 Si. 0.16 Ni, 12.18 Cr. Austenitized at 980 “C (1795 “F). Grain size, 6 to 7
410: Isothermal Transformation Diagram. Modified 410. Composition: 0.22 C, 0.54 Mn. 0.64 Ni. 12.46 Cr, 0.99 MO. 0.29 V. Austenitized at 1010 “C (1850 “F). Grain size, 4 to 5
410: Hardness
vs Tempering
Temperature.
(a) Quenched from 925 “C (1695 “F). (b) Quenched from 1010 “C (1850 “F)
768 / Heat Treaters
Guide
410: Dilatometric Curve. Effects of cooling rates on transfonnation of a chromium stainless steel. Composition: 0.098 C, 0.41 Mn,0.023P.0.010S,0.62Si,0.30Ni.12.30Cr,0.03Mo,0.21Cu. Region of Ar, to Ar, transformation is for slowly cooled dilatometer tests. Ferrite and carbide formation occurs through this range, on slow cooling. Continuation of cooling curves through transfonnation of austenite to martensite, starling at M, point and finishing at M, point. Note the large amount of expansion typlcal of the martensite reaction. Source: Republic Steel
410:
Soak Time for Annealing
and Austenitizing
Thickness(a) tIltI’
in.
Up 10 5 St0 IS
up to 0.250 O\cr 0.250 to O.SOO O~erO.SOOto I OOO Oier l.OfXJto I SW Oicr I.SOOto1OOO O~er1.OOOtoI?.5OO Over 2.500 to 3.OOO O\er 3.ooOto 3.5OO O\er 3.500 to -l.ooO Over 1 COOto 1.500 O\er -1.SMl to S.OOO O~erS.OOOto8CMIO O\tr8OOU
151025 25 to Xl -IO to so 50 to 65 65 to 75 75 IO 90 9010
loo
IIS ll510l2. I2.i 102GO O\er 200 10010
(Aerospace
Practice)
Minimum soak Time (b.c,d,e,f) air or atmosphere I’ min
Minimum soak Tie (b,c,d,ef) salt h
25 -Is
I8 3s -lo 15 so 55
I5 30 -IS IS 30 -4s 30
min
I’ I I I I I
5 IO IS 20 -lo
(a) Thickness is the minimum dimension of the hea\ lest wction of the pan. (b I Soaking shall commence N hen all xmtrol. tndicattng. and recording thermocouples reach the specilied set temperature. or if load thermocouples are used. u hen the part temperature reaches the minimum of the furnace unifcwnity tolerance itt the set temperature. Parts coated with copper plate orsinlilarreflectt\e coatings that tend to rekct radiant heat shall hate their waking time increased b> al least SOq. unless load thermocouples are used. (c)When load thermocouples are used. the c&ing time shall be not less than 30 min. td I In all cases. the parts shall be held for suftisicnt time to ensure that the center of the most massike area has reached temperature and the necessary transformation and diffuston hs\c taken place. (CI hlalimum soah time shall be nrice the mintmum specitied. ekccpt for subcritical annealing tf~ Longer times ma) he necess~ for parts with complex shapes or parts thnr \son’t hrnt unit&ml). ~gt -I h hour plus 30 mtn for r\en 75 mm t 3 in.,. or portion thereofgreater thanXOmm~8 in.). (ht 2 hplus XJmtn forcleq 75 mm 13 in.).orportionthcreofgreatrtrthan 2OOmmtSin.t. Source: .~hlS 27SXS
Martensitic
Stainless
Steels
/ 769
410: Microstructures. (a) Kalling’s reagent, 100x. Stainless-steel in as-forged condition. Hot worked structure is banded delta ferrite (horizontal, light) in martensite matrix. (b) Vilella’s reagent, 100x. Stainless steel, as-forged. Hot worked structure consists of larger, more elongated banded delta ferrite than (a), in martensite matrix. (c) Vilella’s reagent, 100x. Forging. Hardened by: holding 1 h at 980 “C (1795 “F); air quenched: tempered 2 h at 565 “C (1050 “F); and air cooled. Tempered martensite and carbide. (d) Vilella’s reagent, 500x. Strip hardened by rapid air cooling from 980 “C (1795 “F) to room temperature. Tempered 4 h at 205 “C (400 “F). Martensite with precipitated carbide particles. Oblique illumination. (e) Vilella’s reagent, 500x. Strip annealed by holding at 815 “C (1500 “F). Furnace cool to 595 “C (1105 “F). Air cool to room temperature. Matrix of equiaxed ferrite grains with randomly dispersed particles of chromium carbide. (f) Electrolytic: HCImethanol, 500x. Strip in hardened condition: after annealing at 800 “C (1475 “F); holding for 30 min at 955 “C (1750 “F); and air cooled. Ferrite-free martensite. (g) Electrolytic: HCI-methanol, 500x. Same as (f), except less balanced composition. Causes martensite matrix to have islands of ferrite (white). (h)Super picral, 250x. Section through rolled thread on hardened fastener. Austenite reversion at surface, resulting from nitrogen pickup during heat treatment. (j) As-polished, not etched. 100x. Forging: hardened and tempered. Quench crack acquired oxide scale during air tempering.
(continued)
770 / Heat Treaters
Guide
410: Microstructures (continued).(k) Vilella’s reagent, 100x. Same as (j). After etching, the crack was accentuated and revealed tempered martensite and carbide. (m) Super picral, 500x. Hardened and tempered. Cross section shows as-machined surface, after electrochemical machining. Note complete absence of disturbed metal
770 / Heat Treaters
Guide
414 Chemical
COITIpOSitiOn. I .OO Si. 1.25 to 2.50 Ni, Il.50
AISl/UNS (SJ1400): 0.15 c. to 13.50 Cr. 0.04 l? 0.03 S
1.00 hln.
amount of nickel present m the particular ing not recommended
heat being annealed. Full anneal-
Forging. Start forging at Il.50 to 1205 “C i2 100 to 2200 OF). Do not forge after temperature of forging stock drops below 870 to 980 “C ( I600 to I795 “F). Cool slowly from finishing temperature. Anneal
Hardening. Can use atmospheric protection in the form of vacuum, inert gas. salt baths. endothermicor exothermic-generated gas. Parts must be completely clean and free of oil and shop contamination. Thermal conductivity is stgnificantly lower than that of carbon and ahoy steels. High thermal gradients and high stresses during rapid heating may cause warpage and cracking in delicate or intricate parts, Preheat at 760 to 790 “C ( I-100 to I-155 “F). only long enough to equalize temperature in all sections. Estremely delicate or mtricate parts uould benefit from an additional prior preheat of 510°C (lOOOY=). Austenitized at 925 to 1050°C (1695 to 1920 “FL Use upper end of range for larger sections or when maximum corrosion resistance and strength are required. If tempering temperature exceeds 565 “C (I050 “F), use low side of the austenitizing range. It enhances ductility and impact resistance. Soaking time of 30 to 60 min is adequate for sections up to I3 mm (0.50 in. j. Allow an additional 30 min for each additional inch or fraction thereof. Increase soaking time by at least 50% if process annealed for long periods above 675 “C (I 245 “F). Quench in oil or air. Oil quenching preferred. because it guarantees maximum corrosion resistance and ductility. Mutempering in hot oil or salt is suitable because of high hardenability. As-quenched hardness. approximately 388 to -I56 HB
Recommended
Stabilizing.
Similar
Steels (U.S. and/or
Foreign).
AhlS 561% ASTM A276.
A3I-t,A173.ASII.AS80;FEDQQ-S-763;SAEJ10S(SIll-tj
Characteristics. Similar to type -I IO. Nickel added to increase corrosion resistance and strength. Capable of hardening to approximately 15 HRC. Requires about 28 to 32 “C (55 to 75 OF) higher tempering temperature than type 110 to attain same final hardness. Can be quenched in oil or air. Can be martempered. Oil quenching guarantees maximum corrosion resistance. High alloy content causes sluggish transformation and high hardenability. For these reasons. maximum hardness is obtainable by air quenching in center of sections up to approximately 305 nun ( I2 in.) thick. Annealing restricted to process anneal. Good corrosion resistance. Susceptible to stress corrosion cracking in corrosive environments. when stress is above threshold level for that particular environment. Magnetic in all conditions. Fair machinability
Normalizing. Annealing.
Heat Treating
Practice
Do not nomlalize
For best machinability. heat to 955 ‘C ( 1750 “Fj. Temper from 650 to 730 “C ( 1300 to I350 “Fj. Annealed hardness, 99 HRB to 2-t HRC. When the steel is to be subsequently hardened and tempered. tempering at 650 to 730 “C ( I200 to I350 “Fj is sufficient for good machinability. When this treatment does not provide machinability necessary for high-speed tools. it may be advantageous to air cool steel from lo\{ temperature. 815 to 84.5 “C (IS00 to IS55 “Fj. with subsequent temper at 620 to 705 “C ( I I SO IO I300 “F). Exact temperature range go\ emed by actual
To transform essentially all retained austenite. use stabilizing or subzero treatment of -76 to -195 “C (-105 to -320 OF). Temper immediately to temper the new martensite to avoid cracking
Tempering.
Temper at 230 to 650 “C (4.45 to I200 “F). Temper at 230 to 370 “C (US to 700 “F) for hardness approximately 45 HRC. Temper at 595 to 650 “C ( I I OS to I200 “F) for hardness approximately 25 to 3 I HRC. Tempering at 370 to 59s “C (700 to I IO5 “F) not recommended for parts requiring high toughness and optimum corrosion resistance. Causes a marked dip in impact resistance and lowered stress corrosion cracking resistance. Double tempering beneficial. Cool to room temperature bet\\ een tempers
Martensitic
Nitriding. Can be nitrided to case depth of approximately (0.008 in.) in 48 h. See type 410 for further information
0.203 mm
l l l
Recommended l l l l
Processing
Sequence
Forge Anneal Rough machine Stress relieve
414: Hardness vs Tempering Temperature. Composition: 0.13 C,0.54Mn,0.021 P,O.O23S,O.34Si, 1.77Ni, 13.36Cr,O.l9Mo. Heat treated at 1040 “C (1905 “F), VZJh. Oil quenched at 66 to 94 “C (150 to 200 “F). Double stress relieved at 175 “C (345 “F), 15 min. Water quenched. Tempered 2 h. Heat treated, 14 mm (0.550 in.) round. Tested, 12.6 mm (0.505 in.) round. Source: Republic Steel
l l l l l
Stainless
Steels / 771
Finish machine Preheat Austenitize Quench Stabilize (optional) Temper Final grind to size Nitride (if required)
414: Hardness vs Tempering Temperature. Composition: 0.13 C, 0.54 Mn, 0.021 P, 0.023 S, 0.34 Si, 1.77 Ni, 13.36 Cr, 0.19 MO. Heat treated at 925 “C (1700 “F), l/2 h. Oil quenched at 66 to 94 “C (150 to 200 “F). Double stress relieved at 175 “C (345 “F), 15 min. Water quenched. Tempered 2 h. Source: Republic Steel
414: Dilatometric Curves. Composition: 0.104 C, 0.46 Mn, 0.019 P, 0.012 S, 0.32 Si, 1.86 Ni, 12.55 Cr, 0.08 MO. Transformation characteristics shown. Source: Republic Steel
772 / Heat Treaters
Guide
414: Isothermal Transformation Diagram. Composition: 0.10 C. 0.46 Mn. 0.018 P, 0.015 S, 0.33 Si, 1.86 Ni. 12.65 Cr, 0.05 MO. Austenitized at 1040 “C (1905 “F). Rockwell C hardness measured after 24 h at isotherm. Source: Republic Steel
414: Hardness vs Tempering Temperature. 1010 “C (1850 “F). Oil quenched. Tempered 2 h at temperature indicated
772 / Heat Treaters
Guide
416,416Se Chemical
Composition.
416. AISI/UNs
(S41600): 0. IS C. I.3
hln.
1.00 Si, 11.00 to 14.00 Cr. 0.06 P, 0.15 S nin, 0.6 hlo (optional). 416Se. AISI/UNS (S41623): 0. IS C. I .3 hln. I .OO Si. 12.00 to 11.00 Cr. 0.06 P. 0.06 S. 0. IS Se min
Similar
SAl9-k Steels (U.S. and/or Foreign). 416. AWE ASThl A IW. A3 I-!. A473. ASXI. AS82 FED QQ-W-43: hllL SPEC hllL-S-862: SAE J4OS (Sl-llh): (Ger., DIN 1.4005: tFr.j AFNOR Z I2 CF 13; (Ital.) LINI X 12 CrS 13; tSwed.) SSIJ 380: (U.K.1 B.S. 416 S 21. J16Se.4hlSS6l0:AS~~SAl9-1:ASThlAl91,A3I~.A172..L\SlI.A5Xl. AS82: hllLSPEC MU--S-862; SAE J-IO5 (51416 Se)
Characteristics. Another version of tj pe 4 IO, M here S (tl pr 4 I6 I or Se (t)pe 116Se) has been added to improve mashinabilitj. Popular selection for machining m screw machines or turret lathes. Capable of hardening to 42 HRC or slightly higher. Can be tempered to wide range of strength and impact resistance. Deep hardening. Oil quenching recommended. Can be martempered. Tempering in the 370 to S6S ‘C (700 to 1050 OF) range lowers impact resistance. Can be full. process, or isothermal annealed. Good nonseizing and nongalling properties. Good corrosion resistance. Susceptible to stress corrosion cracking in corrosive en\ ironments. u hen stress is aho\? threshold Ir\el for that particulluem ironmsnt. Magnetic in all conditions. Resists oxidation up to 760 ‘C ( 1-U) “F) Forging. Not recommended for forging operations requiring seterr deformation. Sulfur or selenium. added to enhance machinabilit\. tends to create hot shortness. When forged. start forging at I I SO to I260 ‘C (2 100 to 2300 “F). Do not forge after temperature d forging stock drops helou 870 to 980 “C f I600 to 179s “Fj
Recommended Normalizing. Annealing.
Heat Treating
Practice
Do not normalize Can be prows>.
isothermal.
or full annealed:
Procrss wrwtrl in subcritical tempsrature range of 650 to 760 “C (IZOO to IWO “Ft. Lke clean. rectified salt bath or an atmosphere that is compatible with this temperature range. Soaking and softening time dependent on size of work. Air cool. Hardness. 86 to 92 HRB /sor/wwrc~/ mtrtwl hy heating at 830 to 885 “C ( IS3 to I635 OF). Cool blo\s I> to 720 “C ( I330 “F). Hold for 2 h. Hardness. approximately 85 HRB Full mtteal at 830 to 885 “C (153 to 1625 OF). Cool slowly to 595 “C t I IO5 “F) at a rate not to exceed I7 to 12 “C (30 to 10 “F) per h. After this. cooling rate has no effect on hardness. Avoid carburization or decarburization. Can use atmospheric protection in the form of a vacuum. the inert gases argon or helium (both expensive), or nitrogen. All should ha\ e dew pomt belo\\ -5 I “C (-60 “F). Exothermic- or endothermic-generated atmospheres can he used, providing carbon potential of the gas matches carbon content of the steel. Hardness. 75 to 85 HRB. Full annealing is expenke and time consuming. Should not be used. swept as required for subsequent severe foming ln aerospace practice, parts are annealed at 870 “C (1600 “F) and austenitized at 1015 “C ( I875 “F). then quenched in oil or polymer. In annealing, parts are cooled to heIoN 595 “C ( I IO5 “F) at a rate not to exceed 30 “C (55 “F) per h, follo\red b> air cooling to ambient. An austenitizing temperature of 95 “C I I750 “F) is pemitted for thin sections to minimize warpage
Hardening. Atmospheric protection rules for annealing apply to hardening. Parts must be completely clean and free of oil and shop contamination. Thermal conductl\it) IS significantly lower than that of carbon and allo) steels. High thermal gradients and hph stresses during rapid heating ma) cause irarpage and cracking in delicate or intricate parts. Preheat at 760 to 790 “C ( I100 to 1455 ‘Fj. only long enough to equalize temperature in all sections. Extremely delicate or intricate parts would benefit from an additional prior preheat of S-IO “C ( 1000 OF). Austenitized at 925 to 1010 “C t 1695 to I850 “Fj. Llse upper end of range for larger sections or when masimum corrosion resistance and strength are required. lf tempering
Martensitic temperature exceeds 565 “C (IO50 “F), use low side of the austenitizinp range. It enhances ductility and impact resistance. Soaking time of 30 to 60 mitt is adequate for sections up to I3 mm (0.50 in.). Allow an additional 30 min for each additional inch or fraction thereof. Double soaking time if parts have been full or process annealed. Increase time by SO%, if process annealed above 675 “C (I245 “F). Oil quench. Martempering in hot oil or salt is suitable because of high hardenahility. As-quenched hardness, approximately 375 to 4 IS HB
Stabilizing.
To transform essentially all retained austenite, use stabilizing or subzero treatment of -76 to -195 “C (-105 to -320 “Fj. Temper immediately to temper the near martensite to avoid cracking
Temper at 205 to 760 “C (300 to l-IO0 “F). Temper at 205 to 370 “C (100 to 700 “F) for hardness approximately 35 to -IS HRC. Temper at 565 to 605 “C ( 1050 to I I25 “F) for hardness approximately 25 to 3 I HRC. Tempering at 370 to 565 “C (700 to 1050 “FJ not recommended for parts requiring high toughness and optimum corrosion resistance. Causes a marked dip in impact resistance and lowered stress corrosion cracking resistance. Double tempering beneficial. Cool to room temperature hetvveen tempers
416: Hardness vs Tempering Temperature. Composition:
0.11 C, 0.87 Mn, 0.018 P, 0.360 S, 0.42 Si, 0.33 Ni, 13.08 Cr, 0.09 MO. Heat treated at 980 “C (1795 “F), li2 h. Oil quenched at 66 to 94 “C (150 to 200 “F). Double stress relieved at 175 “C (345 “F). 15 min. Water quenched. Tempered 2 h. Heat treated 14 mm (0.550 in.) ?ound. Tested, 12.8 mm (0.505 in.) round. Source: Republic Steel
416: Microstructures.
Steels / 773
Nitriding. Can be nitrided to case depth of approximately 0.203 nun (0.008 in.) in approximately 38 h. See type 310 for further information
Recommended l l l l l l l l
Tempering.
Stainless
l l l l
Processing
Sequence
Forge Anneal Rough machine Stress relieve Finish machine Preheat Austenitize Quench Stabilize (optional) Temper Final grind to we Nitride (if required)
416: Partial Isothermal
Transformation Diagram. Free-machining steel. Composition: 0.12 C, 0.79 Mn. 0.017 P. 0.190 S, 0.74 Si. 0.25 Ni. 12.82 Cr, 0.05 MO. 0.037 N. 0.08 Zr. Austenitized at 980 “C (1795 “F). Grain size, 7 to 9
(a) Polished, not etched. 250x. Bar stock with 0.150 S max, to promote chip breakage and improve machinability. Longitudinal section. Cross section shows elongated, stnnger-type inclusions of manganese sulfide (horizontal dark streaks). (b) Vilella’s reagent, 500x. Bar, austenitized at 980 to 1010 “C (1795 to 1850 “F). Oil quenched. Tempered at 565 “C (1050 “F). Stringers of manganese sulfide (dark) and blocky ferrite (light, outlined). Matrix of tempered martensite. (c) 596 picric acid and 19,” hydrochloric acid, 750x. Bar in annealed condition. Longitudinal cross section. Delta ferrite (light etching) in matrix of tempered martensite. Stringers of manganese sulfide (dark, elongated)
774 / Heat Treaters
Guide
416: isothermal Transformation Diagram. Free-machining steel. Composition: 0.10 C, 0.94 Mn, 0.025 P. 0.350 S. 0.44 Si, 0.31 Ni, 12.40 Cr, 0.44 MO. Austenitized at 900 “C (1650 “F). Source: Republic Steel
416: Hardness vs Tempering Temperature. Composition:
0.11 C, 0.87 Mn, 0.018 P, 0.360 S, 0.42 Si, 0.33 Ni, 13.06 Cr, 0.09 MO. Heat treated at 925 “C (1695 “F), ‘12h. Oil quenched at 86 to 94 “C (150 to 200 “F). Double stress relieved at 175 “C (350 “F), 15 min. Water quenched. Tempered 2 h. Heat treated 14 mm (0.550 in.) round. Tested, 12.8 mm (0.505 in.) round. Source: Republic Steel
Martensitic
416:
Soak Time for Annealing
and Austenitizing
Tbicknfs(a)
mm
in.
up 10 5 510 IS 15 1025 2s to 30 JO to so SO IO 65 65 to 75 75 10 90 9oro loo lOOto 11s 11510 125 125 to200 Over 200
up to 0.250 Over 0.250 10 0.500 Over 0.500 10 I .OOO Over I .OOO10 I.500 Ober I.500 10 2.000 Over 2.000 10 2.500 O\er 2.SOO 10 3.000 Over 3.ooO to 3.900 Ober 3.SOO 10 1.000 0ver4.000~04.500 Over J.500 10 5.000 Over 5.000 10 8.GOO Oker 8.OOO
(Aerospace
Stainless
Steels / 775
Practice)
Minimum soak Tie (b,c,d,efi air or atmosphere II min
Minimum
Tie b
25 15
soak
(b,c,d,ef) salt min I8 35 40 4.5 SO 55
I5 30 45 I I
IS 30 4s
I
SO
I I Ih)
I
‘i IO IS 20 10
(a) Thickness is the minimum dimension of the heal iesI section of the pan. I b) Soaking shall commence u hen all control. indicating. and recording lhermocouples reach Ihe specitied set temperature. or if load thermocouples are used, when the pan temperature reaches rhe minimum of Ihe furnace uniformir) tolerance at the set rrmperature. Pans coated with copper plate or similar rekctive coaungs rhar rend IO reflecl radiant heal shall hate their soaking lime increased by a~ leas1 SOCr. unless load thermocouples are used. (c) When load thermocouplesare used. the soaking time shall be not less than 30min. (d) ln all czxs. the parts shall be held for sufficient time tornsure [hat the centerof the most massitearea has reached temperature and the necessary lmnsformation and diffusion have taken place. (e I hlaxlmum soak time shall be IN ILX the mimmum specified. except for subcritical anneallng. (0 Longer times mav be necessaq for pcins with complex shapes or par& that won’t heat uniformI>. (go 1 h hour plus 30 mm for cveq 75 mm (3 in. ). or ponion thereof greater than 200 mm (8 in.). (h) 5 h plus 20 mm for ever) 75 mm (3 in.), or portion thereof greater than 200 mm (8 in 1. Source: AI\lS 1759/S
Martensitic
Stainless
Steels / 775
420,420F Composition. 420. AlS1pJN.S(S42000):0.15 C min. I .OO Mn. 0.04 P. 0.03 S. 1.00 Si. 12.00 IO 14.00 Cr. J20F. (UNS S42020): 0.15Cmin. 1.2SMn. l.OOSi. 12.00to l-L00Cr.0.06P,O.lSSmin.0.6hlo (optional) Chemical
Similar
Steels (U.S. and/or Foreign). Ito. AhlS ASTM A276. A3 I-l. A-l73. AS80; FED QQ-S-763. QQ-S-766. hllL SPEC MIL-S-862: SAE J-IO5 (5l-l20); (Ger.) DIN AFNOR Z 20 CB; (Ital.) UNI X 20 Cr I3 X I; (Jap.) JIS (Sa,ed.)SSt~7303:(l!.K.) B.S.-l?OS 37.CDS-18. En. S6C. AMS 5620; SAE J-l05 (5 l-i70 F)
5506. 5621; QQ-W-133: 1.4071; (Fr.) SUS 470 II: 3s. 62.42OF.
Characteristics.
Deep hardening. Can be hardened to slightly over 500 HB. Quenched in oil or air. Can be readill mat-tempered. hlagnetic in all conditions. Optimum corrosion resistance in hardened and tempered condition. Can be full, process, or isothermal annealed. Used for cutler? and general use where strength. ductility. and corrosion resistance are desired. Type 420F is a free-machining version of -170. Sulfur added to -I20F to improve machining and nonseizing characteristics. Processing the same as for 410. except a higher initial forgmg temperature used to minimize hot short cracking
Forging. For type 420. start forging at 1065 to 1205 “C (I950 to 1200 “F). Do not forge after temperature of forging stock drops below 900 “‘C (1650 OF). For type 420F. forge at I I20 to I230 “C (2050 to ??-I5 “F). Cool very slowly from fmishing temperature. Anneal
Recommended Normalizing. Annealing. l
Heat Treating
Practice
Do not normalize Can be process. isothermal.
or full annealed:
Process unn& in subcritical temperature range of 675 to 760 “C ( I215 to I400 “F). Use clean. rectified salt bath or an atmosphere that is compatible uith this temperature range. Soaking and softening time dependent on size of work. Air cool. Hardness. 9-l to 97 HRB
lsorhrrrnal ~rr~ea/ by heating at 830 to 885 “C ( 1575 to 1625 “F). Cool slowl) to 705 “C ( I300 “FL Hold for 2 h. Hardness. approximately 95 HRB Full ur~rreu/ at 830 to 885 “C ( IS25 to I625 OF-,. Cool to 595 “C (I IO5 “FJ at a rate not to exceed I7 to 22. “C 130 to 40 “F) per h. After this. cooling rate has no effect on hardness. Avoid carburization or decarbunzation. Can use atmospheric protection m the form of a vacuum. the inert gases argon or helium (both expensive). or nttropen. All should have dew point below -5 I “C t-60 ‘F). Endothemtic-generated atmospheres can be used by holding deu point at 0.10 to 0.25 carbon for annealing temperature used. Annealed hardness. 86 to 95 HRB. Full annealing is expensive and time consuming. Should not be used, except as required for subsequent severe forming or specialized metal cutting operations In aerospace practice. 120 is annealed at 870 “C ( I600 “F). It is cooled to below 595 “C ( I IO5 ‘F) at a rate not to exceed 30 “C (55 OF) per h. followed by slow cooling to ambient. Parts ate austenitized at 1025 “C (I875 “F). and quenched in oil or polymer
Hardening. Atmospheric protection rules for annealing apply to hardening. Parts must be completely clean and free of oil and shop contamination. Thermal conducti\ ity is significantIT lower than that of carbon and allo! steels. High thermal gradients and high stresses during rapid heating ma) cause warpage and cracking in delicate or intricate parts. Preheat at 760 to 790 “C (l-100 to 1155 “F). onI> long enough to equalize tenlperaNre in all sections. Estremel~ delicate or intricate parts would beneFtt from an additional prior preheat of 510 “C ( 1000 ‘FL Austenitized at 980 to 1065 YY i I795 to 1950 “F). Use upper end of range for larger sections or when maximum corrosion resistance and strength are required. If tempering temperature exceeds 565 “C (1050 ‘FL use low side of the austenitizing range. It enhances ductility and impact resistance. Soaking time of 30 to 60 min is adequate for sections up to I3 mm (0.50 in.). Allow an additional 30 min for each additional inch or fraction thereof. Double soaking time if parts ha\e been full or isothermal annealed. Increase time by 50%. if process annealed for long; periods above 705 “C I I300 jF). Quench in oil or air. Oil quenching preterred. because it guarantees maximum corrosion
776 / Heat Treaters
Guide
resistance and ductility. hlartempering In hot oil or salt is suitable because of high hardrnabilib. As-quenched hardness. approximately-U8 to 56-l HB
Recommended l
Stabilizing. For minimum retained austwite and maximum dimcnsional stabilib. use subzero treatment at -74 “C (- IO0 + 20 “F). This should incorporate continuous cooling from austenitirinp temperature to ths cold transformation temperature
l l l l l
Tempering.
Temper at 205 to 370 “C (400 to 700 “F). Hardness of -18 to 56 HRC. Double tempertng beneficial. Cool to room tempzraturc betueen tempers
l l l l
Nitriding. Can bc nitrided to case depth of approxImateI> t0.008 in.) in -IX h. Set t>pr 110 for further information
0.203 mm
l l
Processing
Forge Anneal Rough machine Stress relieve Finish machine: Preheat Austenitize Quench Stabilize (not mandator\. Tsmpcr Final grind to size Nitride (if required)
Sequence
but beneficial)
420: Isothermal
Transformation Diagram. Composition: 0.35 C, 0.42 Mn, 0.016 P. 0.013 S, 0.45 Si, 0.31 Ni. 13.00 Cr, 0.10 MO. Austenitized at 980 “C (1795 “F). Rockwell C hardness measured after 24 h at isotherm. Source: Republic Steel
420: Hardness vs Tempering Temperature. Composition:
0.31 C, 0.43 Mn. 0.022 P. 0.011 S. 0.45 Si. 0.44 Ni, 13.12 Cr. Heat treated at 925 “C (1695 “F), !/2 h. Oil quenched from 66 to 94 “C (150 to 200 “F). Double stress relieved at 175 “C (345 “F), 15 min. Water quenched. Tempered 2 h. Heat treated, 14 mm (0.550 in.) round. Tested. 12.8 mm (0.505 in.) round. Source: Republic Steel
420: Hardness vs Tempering Temperature. Composition:
0.31 C, 0.43 Mn, 0.022 P, 0.011 S, 0.45 Si, 0.44 Ni, 13.12 Cr. Heat from 66 to 94 “C treated at 1025 “C (1875 “F), 1 h. Oil quenched (150 to 200 “F). Double stress relieved at 175 “C (345 “F), 15 min. Water quenched. Tempered 2 h. Heat treated, 14 mm (0.550 in.) round. Tested, 12.8 mm (0.505 in.) round. Source: Republic Steel
Martensitic
420,420F:
Soak Time for Annealing
Tie
Thickness(a) mm UptoS St0 1s 15 to3 ‘SlO-Kl
4otos0 501065 6S to 75 7s to 90 9oto 100 lOOto il.5 llfito 12s 12st0300 Over 200
and Austenitizing
in.
Over Over O\er Oker Ober Over Over Over Over Over Oker
up to 0.30 0.150 to 0.500 O.SOO to I BOO I .ooO to I .SOO I .SOO to 1.OfKl ~.OOClto XC0 2.500 to 3.OOO 3.00@ to 3.500 3.500 to -!.ooO 1.00@ to 4 SO0 4.500 to S.000 S.OGO to WOO O\er X.OCU
h
(Aerospace
‘8’
Steels / 777
Practice)
Minimum soak (b,c,d,e,tJ air or atmosphere min
hlinimum soak Tie (b,c,d,c,f) salt h
2s -1.5 I I I I 2 2 2 2 3 3
Stainless
I8 3s 40 -15 so ss
IS 30 -1.5 IS 30 15 30
min
I I I I I I th,
5 IO IS 20 40
ts)Thickness is the minimum dimension of the heaiest action ofthe part. t hl Soaking shall commence w hen all control. indiaating. and recording thermocouples reach the specified set temperature. or if load thermocouplss are used, when the part temperature reaches the minimum of the furnace uniformity tolerance at the set temperature. Parts coated with copper plate or similar reflective coatings that tend to retlect radiant heat shall ha\e thrtr soaking time increased by at lrasr SOG. unless load thermocouples are used (c)When load thermocouples are used. the soaking time shall be not less than 30 min. td) In all cases, the parts shall he held for suffkient time to ensure that the center of the most massive area has reached temperature and the necessary transfomlation and diffuston hate taken place. (et hlaximum soak time shall he twtce the mimmum spxified. except for subcritical annertlinp. ff) Longer times may be necessary for parts withcomplex shapesorparts that \ron’t heat uniformI>. tgr-4 h hour plus 30 min forr\ery 75 mm (3 in.Lor portion thereofgreater than 301nm (8 in.). th) 2 h plus 1Omin foresery 7S mm (3 in.). or portion thercofgreaterthan NOmm (8 in.). Source: .AhlS 27.59/S
Martensitic
Stainless
Steels / 777
422 Chemical
Composition. AISIjlJNS (S42200): 0.20 to 0.3 C. I .OO Mn. 0.04 P. 0.03 S. 0.75 Si. 0.5 to I.0 Ni, I I.50 to 13.50 Cr. 0.75 to I.25 hlo: 0. IS to 0.3 v; 0.75 to I.25 CI
Similar Steels (U.S. and/or Foreign). AhlS 5655: ASTM (616); SAE 5167; (Ger.) DIN 1.4935: (lap.) JIS SUH 616
AS65
Characteristics.
Designed for service temperatures up to 650 “C. (I200 “F) with a combination of high strength and toughness. Carbon content. 0.20 to 0.25. Carbide-forming elements. MO. V. and W added for high-temperature strength. Somewhat restricted use. pnmarily for turbtne blades and hioh-strength fasteners for corrostve environment application. Deep hardening. Hardened hy air cooling or oil quenching,. Process annealing, rather than full annealing. recommended. Magnetic m all conditions. hledium IO low machinahilit~
benefit from an additional prior preheat of 5-U) “C ( IO00 “F). Austenhized at IO-IO “C (I905 “F) for I II. Xir cool or uater quench. In aerospace practice. parts are austenitized at IO55 “C t 1930 “F). and quenched in oil. polymer. or salt. Salt temperature must he 190 IO 275 “C (375 to 525 “F): pnrts are held in salt IO to IS mitt; then removed and cooled in air to room temperature
Stabilizing.
For minimum retained austettite and maximum dimensional stabilit). USC a subzero treatment of -7-t ‘C (-100 + 20 “F). This should incorporate continuous cooling from the austenitizing temperature to the cold transformation temperature
Tempering. temperature HB.
Temper at 6.50 “C I I200 “F) or at least to maximum sewice for 2 h. Hardened and tempered hardness, approximately 320
Forging. Start forging at I IS0 “C i2 100 “‘F). Do not forge after tempemture of forging sock drops below 955 “C (I750 OF). Cool vrq slowI! from finishing temperature. Anneal
Nitriding. Can he nitrided to case depth of approximateI> (0.008 in.) in 48 h. See type -IlO for further information
Recommended
Recommended
Normalizing.
Heat Treating
Practice
l
Do not normalize
l
Annealing.
Processanneal at 730 to 790 “C ( I350 to l-155 In aerospace practice, parts are annealed at 870 “C ( I600 cooled to 705 “C (I 300 “FL held for 5 to 7 h. cooled IO below “F) at a rate not to exceed 30 “C 155 “F) per h. and air cooled Hardening.
‘;F). Air cool. “F). The! are S-IO “C ( IO00 to ambient
Parts must be completely clean and free of oil and shop contamination. Thermal conductkity is significantly lower than that of carbon and alloy steels. High thermal gradients and high stresses during rapid heating may cause warpape and cracking in delicate or intricate parts. Preheat at 760 to 790 “C (14lO to 1155 “F). onl) long enough IO equalize temperature in all sections. Extremely delicate or intricate parts would
l l l l l l l l l l
Processing
Forge Anneal Rough machine Stress relic\ e Finish machine Preheat Austcnitize Quench Stabilize (not mandntor~. Temper Final grind to size Nitride (if required)
but beneficial)
Sequence
0.203 mm
778 / Heat Treaters
422:
Guide
Soak Time for Annealing
and Austenitizing
Thickness(a) up to 5 510 IS I5 to25 25 to-t0 4otoso so IO 65 65 Ill 7s 75 to90 9oto1ocl looto11s 1lstol2s 115l0200 Over 200
Tie in.
mm Ober Ober Over Over O\er Over Oter Over Over Over Over
(Aerospace
up to 0.250 0.750 to 0.500 0.500 to I BOO I.000 to I SO0 I SO0 to 2.OCfl 2.000 to 2.500 2.500 to 3 000 3.000 to 3.SCO 3.500 to -I 000 JONI to 4.500 1.SOO to .S.OCO 5.000 to 8.OCO Over 8.000
Practice)
Minimum soak (b,c,d,Q air or atmosphere b min
Minimum soak Tie (b,c,d,e,f) salt h
25 45 I I I I 3
2 1 3 3 3 (g)
I8
35 40 45 50 55
I5
30 1s IS 30 -IS 30
mill
I I I I I I (h)
5 IO 15
20 40
(a) Thickness is the minimum dimension of the heaviest section of the part. tb) Soaking shall commence u hen all control. indicating, and recording thermocouples reach the specified set temperanne. or if load thermocouples are used. when the part temperature reaches the minimum of the furnace uniformity tolerance at the set temperature. Parts coated with copper plate or similar reflectike coatmgs that tend to reflect radiant heat shall have their soaking time increased by at least 50%. unless load thermocouples are used. (c) When load thermocouples are used the soaking time shall he not less than 30 min. (d) In all cases. the parts shall be held for sufficient time to ensure that the center of the most massive area has reached temperature and the necessaq transformation and diffusion have taken place. te) hlaximum soak time shall be twice the minimum specified. except for subcritical annealing. (II Longer times ma\ be necessq for parts with complex shapes or parts that won’t heat uniformI). (g) 4 h hour plus 30 min for ebery 75 mm (3 in.), or portion thereofgreater than NOmm (8 tn.). th)? hplus 20 min forevery 75 mm (3 tn.). or portion thereofgreaterthm XOmmt8 in.) Source: Ah% 275915
Martensitic
Stainless
Steels / 779
431 Chemical
Composition.
AISI/UNS
(S43100): 0.20 c. 1.00 Ia,
I .OO Si. I.25 to 2.50 Ni. 15.00 to 17.00 Cr. 0.0-l P. 0.03 S
Similar
Steels (U.S. and/or Foreign). AMS 5628; ASTM ~276. A3 14. A473. A493. A579 (63). AS80: MlL SPEC hUL.-S-862; SAE 1105 (51331); (Ger.) DIN 1.4057; (Ital.) UNI X 16CrNi 16; (Jap.) JIS SW 431; (Swed.) SS1.t 2321; (U.K.) B.S. 431 S. 29, 5 S 80 Characteristics. Designed for heat treating to high mechanical properties by higher additions of Cr and Ni. Also causes increased corrosion resistance over types 4 IO. 420.430. and 440. Quenched in oil or air. Can be mar-tempered. Tempering from 370 to 565 “C (700 to 1050 “‘F) not recommended. Generally benefits from subzero treatment after quench. Process anneal only. Annealed hardness. 22 to 30 HRC. Magnetic in all conditions. Low machinability Forging. Start forging at I I50 to I230 “C (2 100 to 2245 “F). Do not forge after temperature of forging stock drops below 925 “C ( I695 “F). Cool very slowly from finishing temperature. Anneal
Recommended Normalizing.
Heat Treating
Practice
Do not nomlalize
“F). Quench in oil or air. Oil quenching preferred. because it guarantees maximum corrosion resistance and ductility. Martempeting in hot oil or salt is suitable because of high hardenability. As-quenched hardness, approximately 401 to -t-t4 HB. Tendency to exhibit segregation or banding. Prevents uniform hardening and may seriously reduce mechanical properties. particularly in the transverse direction. For limited austenite segregation. heat slowly to 1205 “C (2200 “F). Hold for I h. Cool slowly to room temperature. Repeat the above heating, holding and cooling twice. for a total of three cycles. Heat to 8 I5 “C ( IS00 “F). Air cool. In aerospace practice, parts are austenitized at 1025 “C (I875 “F), and quenched in oil. polymer. or salt. Salt temperatures range from 190 to 275 “C (375 to 525 “F). Parts are held in salt for IO to I5 min. then removed and air cooled to room temperature. After the hardening quench. 43 I and 430C parts are cooled by immersing them in cold water to ambient temperature water. They are then refrigerated at -70 “C (-95 “F) or lower for not less than 2 h
Stabilizing. For minimum retained austenite and maximum dimensional stability, use subzero treatment at -74 “C (-100 + 20 “F). This should incorporate continuous cooling from austenitizing temperature to the cold transformation temperature Tempering.
Annealing.
Temper at 230 to 605 “C (445 to I I25 “F). Temper at 230 to 370 “C (44s to 700 “Fj for hardness approximately 10 to 47 HRC. Temper at 565 to 605 “C ( 1050 to I I25 “F) for hardness approximately 26 to 3-t HRC. Tempering at 370 to 565 “C (700 to I050 “F) not recommended for parts requiring high toughness and optimum corrosion resistance. Causes a marked dip in impact resistance and lowered stress corrosion cracking resistance. Double tempering beneticial. Cool to room temperature between tempers
Hardening.
Nitriding. Can be nitrided to case depth of approximately (0.008 in.) in 48 h. See type -II0 for further information
Full or isothermal annealing not recommended. Process anneal by holding at 620 to 705 “C ( I I50 to I300 “F) for sufftcient time to achieve desired ductility or machinability. 6 h minimum at temperature. A clean. rectitied molten salt bath can be used. Air cool parts from annealing temperature. In aerospace practice, parts are annealed at 870 “C (I 600 “F), then air cooled to ambient temperature followed by heating to 650 “C ( I200 “F) for IO to I2 h and air cooled For endothermic atmosphere. use dew point of IS to I8 “C (60 to 65 “F) for austenitizing temperature of 980 “C ( I795 “F). Parts must be completely clean and free of oil and shop contamination. Thermal conductivity is significantly lower than that ofcarbon and alloy steels. High thermal gradients and high stresses during rapid heating may cause warpage and cracking in delicate or intricate parts. Preheat at 760 to 790 “C ( 1400 to 1455 “F), only long enough to equalize temperature in all sections. Extremely delicate or intricate parts would benefit from an additional prior preheat of 540 “C (1000 “F). Austenitized at 980 to 1065 “C (1795 to 1950 “F). Use upper end of range for larger sections or when maximum corrosion resistance and strength are required. If tempering temperature exceeds 565 “C (1050 “F). use low side of the austenitizing range. It enhances ductility and impact resistance. Soaking time of 30 to 60 mitt is adequate for sections up to I3 mm (0.50 in.). Allow an additional 30 mm for each additional inch or fraction thereof. Double soaking time if parts have been full or isothermal annealed. Increase time by 50%. if process annealed at 675 “C ( I245
Recommended l l l l l l l l l l l l
Processing
Forge Anneal Rough machine Stress relieve Finish machine Preheat Austenitize Quench Stabilize (not mandatory, Temper Final grind to size Nitride (if required)
but beneficial)
Sequence
0.203 mm
780 / Heat Treaters
Guide
431: Hardness vs Tempering Temperature. Composition: 0.14 C,0.46Mn,0.014P,0.012S,0.44Si,2.18Ni, 16.40Cr,O.lOMo. Heat treated at 1040 “C (1905 “F), !4 h. Oil quenched from 66 to 94 “C (150 to 200 “F), 15 min. Water quenched. Tempered 2 h. Heat treated, 14 mm (0.550 in.) round. Tested, 12.8 mm (0.505 in.) round. Source: Republic Steel
431: Hardness vs Tempering Temperature. Composition: 0.14 C,0.46Mn,0.014P,0.012S,0.44Si,2.18Ni,16.40Cr,0.10Mo. Heat treated at 925 “C (1695 OF), ‘I2 h. Oil quenched from 66 to 94 “C (150 to 200 “F). Double stress relieved at 175 “C (345 “F), 15 min. Water quenched. Tempered 2 h. Heat treated, 14 mm (0.550 in.) round. Tested, 12.8 mm (0.505 in.) round. Source: Republic Steel
431: Isothermal Transformation Diagram. Composition: 0.16 C. 0.40 Mn. 0.018 P, 0.010 S. 0.43 Si. 2.44 Ni, 16.42 Cr. Austenitized at 1040 “C (1905 “F). Rockwell C hardness measured after 24 h at isotherm. Source: Republic Steel
431: Hardness vs Tempering Temperature. tempered 2 h at 980 “C (1795 “F)
Oil quenched
and
Martensitic
431:
Soak Time for Annealing
and Austenitizing
Thickness(a) mm uptos 510 I5 151025 xto40 -lo to 50 SO to 65 65 to 75
75 to90 9010 loo loot0 11s 11510125 12s 10’00 Over Xl
in. Over Over Over Over Over Oker Over Over Over Over OLer
up to 0.250 0.150 to OSCNI 0.500 to I .ooO I .OOOto I.500 I .SOO to 2.ooO 2.000 to 2.SOO 2.500 to 3.000 3.000 to 3.500 3.500 to 4.000 3.OGU to 4.500 3.500 to 5.000 S.ooO to 8.OOO Ober 8.000
(Aerospace
Stainless
Steels / 781
Practice)
Minimum soak Tie (b,c,d.e,f) air or atmosphere II min
Minimum soak Tie (b+,d,e,fj salt h
25 45
I8 35 40 15 50 55
I5 30 IS ii 30 -l5 30
min
! I I I I I th)
5 IO IS 20 40
(a) Thickness is the minimum dimension of the heaviest section of the part. I hl Soakmg ihall commence H hen all control, indicating. and recording thermocouples reach the specitied set temperature. or If load thermocouples are used. u hen the part temperature reaches the minimum of the furnace uniformity tolerance BI the set temperature. Pans coated with copper plate or similar rellectite coatings that tend IO reflect radiant heat shall haie their soaking time increased by at least 505, unless load thermocouples are used. (c I When load thermocouples are used. the soaking time shall be not less than 30 min. Cd) tn all cases. the parts shall be held for sufticient time to ensure that the center of the most massive area has reached temperature and the necessary transformation and diffusion have taken place. lei hlautmum soak nme shall be twice the minimum specified. except for subcritical annealing. (0 Longer times may be necessaq for parts with complea shapes or parts that u on’t heat uniforml). ~gr -1 h hour plus 30 nlin ior e\er) 75 mm I 3 in. ). or portion thereof greater thanXJOmm(8in.). (hj2 h plus2Omin foreveq 75 mm0 in.).orportion thereofgreater than2OOmm 18 In I. Source. AhlS ?759/5
Martensitic
Stainless
Steels / 781
440A Chemical
Composition.
AISl/UNS (WOO2): 0.65 to 0.75 C. I .OO
Mn. I .OO Si. 16.00 to 18.00 Cr. 0.01 P. 0.03 S, 0.75 MO
Similar
Steels (U.S. and/or Foreign).
A3 I-1. A373, AS I I, AS80; FED QQ-S-763; J4OS (5 I440 A)
~hls 563 I : ASTM ~276. hllL
SPEC MIL-S-86’:
SAE
Characteristics.
Greater hardenability than type 420. Greater touphness than -UOB or UOC, because of lower carbon. Good corrosion resistance, particularly in hardened and tempered condition. Quenched in oil or air. Can be martempered. Can he full. process. or isothermal annealed. Magnetic in all conditions. Low machinability. Used for cutlery. hearings. and surgical tools
Forging. Start forging at I040 to I205 “C t 1905 to 2200 “Fj. Do not forge after temperature of forging stock drops belo\\ 9SS “C t 1750 “Fj. Cool slowly from finishing temperature. Anneal
Recommended Normalizing. Annealing.
Heat Treating
Practice
Do not nomlalize Can he process, isothermal.
or full annealed:
Process ajuwal in subcritical temperature range of 675 to 760 “C t INS to 1400 “F) for hardness of 90 HRB to 27 HRC. LJse clean. rectified hath or an atmosphere that is compatible (such as bacuumj. Soaking and softening time dependent on size of work. Air cool /sor/1entu7/ unnecrl by heating at 815 to 900 “C ( 1555 to I650 “Fj. Cool slowly to 690 “C ( I275 “F). Hold for 1 h. Hardness. approximately 98 HRB Full untwal at 8-O to 900 'T ( 1.555 to 1650 “Fj. Cool to S9S ‘C t II05 ‘T) at a rate not to exceed I7 to 32 _ “C (30 to -IO “F) per h. After this. cooling rate has no effect on hardness. Avoid decarburization. Can use atmospheric protection in the foml of a vacuum. the inert gases argon or helium (both expensive), or nitrogen. All should have dew point helow -5 I “C (-60 “Fj. Endothermic-generated atmospheres can be used
hy holding de\{ point in the 0.60 to 0.75 carbon range. for the annealing temperature used. Annealed hardness. 9-t to 98 HRB. Full annealing is espenske and time consuming. Should not be used, except as required for subsequent severe forming or specialized metal-cutting operations
Hardening. Atmospheric protection rules for annealing apply to hardening. Parts must be completely clean and free of oil and shop contamination. Thermal conductivity is significantly lower than that of carbon and alloy steels, High thermal gradients and h&h stresses during rapid heating may cause ~arpage and cracking in delicate or intricate parts. Preheat at 760 to 790 ‘C t I-W to l-155 “Fj. only long enough to equalize temperature in all sections. Extremely delicate or intricate parts would benefit from an additional prior preheat of S-10 “C tIOO0 “Fj. Austenitize at 1010 to 1065 “C i I850 to 1950 “Fj. LJse upper end of range for larger sections or when maximum corrosion resistance and strength are required. Soaking time of 30 to 60 min is adequate for sections up to I3 mm tO.50 in.). Allow an additional 30 min for each additional inch or fraction thereof. Double soaking time if parts have heen full or tsothemwl annealed. Increase time hy SO? . if process annealed abo\ e 67S “C t I215 “F). Quench in oil or air. Oil quenching preferred. because it guarantees maximum corrosion resistance and ductility. hlartempering in hot oil or salt is suitable because of high hnrdenahility. As-quenched hardness. approximately 52 to S7 HRC Stabilizing. For minimum retained austenite and maximum dimensional stability. use suhzero treatment at -71 “C t-100 f 20 “F). This should incorporate continuous cooling from austenitiring temperature to the cold transformation temperature Tempering.
Temper at IS0 to 370 “C t300 to 700 “F) for hardness approxmlately -18 to 57 HRC. Double tempering beneficial. Cool to room temperature between tempers
Nitriding. Can he nitridcd to case depth of approximately tO.008 in.) in 18 h. See type 1 IO for further information
0.203 mm
782 / Heat Treaters
Recommended l l l l l l
Forge Anneal Rough machine Stress relieve
Finish machine Preheat
Guide
Processing
Sequence
l l l l l l
Austenitize Quench Stabilize (not mandatory. but beneficial) Temper Final grind to size Nitride (if required)
440A: Partial lsoth ermal Transformation .:--.
Diagram. Composi-
,?.rn n nrr ..’ LIUII: nU.DL b, nU.JU rwn, 0.17 Si, 16.59 Cr. Austenitized ,A . ..-.r.nr,
at 870 “C
(Iouu-rj
440A: Microstructures. (a) 5% pick acid and 3% HCI, in alcohol. 500x. Bar in annealed condition. Longitudinal cross section. Chromium carbide particles in ferrite matrix. (b) 1% pick acid and 5% HCI, in alcohol. 500x. Austenitized at 1010 “C (1850 “F), ‘4 h. Air cooled. Tempered at 595 “C (1105 “F), l/2 h. Partly spheroidized particles of chromium carbide in martensite matrix
782 / Heat Treaters Guide
440B Chemical Composition.
AISI/IJNS (~44003): 0.75 Mn. 1.00 Si. 16.00 to 18.00 Cr. 0.04 P. 0.03 S. 0.75 MO
Similar Steels (U.S. and/or Foreign).
ASTM A473. A580; FED QQ-S-763; MIL SPEC MIL-S-862; B); (Ger.) DIN I .4 I 12; (lap.) JIS SUS UO B
IO
0.95 c, I .oo
~3 II. A276, SAE J105 (51130
Characteristics. Greater hardenahility than type 320 and UOA. Greater toughness than 44OC. Good corrosion resistance, particularly in hardened and tempered condition. Quenched in oil or air. Can be martempered. Can be full, process. or isothermal annealed. Magnetic in all conditions. Low machinability. Used for cutlery, valve parts. and instrument bearings Forging. Start forging at 1040 to I I75 “C ( 1905 to 2150 “F). Do not forge after temperature of forging stock drops below 955 “C (I750 “F). Cool slowly from tinishing temperature. Anneal Recommended Heat Treating Normalizing. Do not normalize Annealing. Can be process. isothermal.
Practice or full annealed:
Process nr~enl in subcritical temperature range of 675 to 760 “C (1245 to 1400 “F) for hardness of 98 HRB to 23 HRC. Use clean, rectified salt bath or an atmosphere that is compatible with this temperature range. Soaking and softening time dependent on size of work. Air cool lsorhernlal arrnrul by heating at 845 to 900 “C ( I555 to 1650 “F). Cool slowly to 690 “C ( 1275 “F). Hold for 1 h. Hardness. approximately 20 HRC Full mnea/ at 845 to 900 “C ( 1555 to 1650 “F). Cool to 595 “C (I I05 “F) at a rate not to exceed I7 to 22 “C (30 to 40 “F) per h. After this. cooling rate has no effect on hardness. Avoid decarburization. Can use atmospheric protection in the form of a vacuum, the inert gases argon or helium (both expensive), or nitrogen. All should have dew point below -51 “C (40 “F). Endothermic-generated atmospheres can be used by holding dew point in the 0.75 to 0.95 carbon range for the annealing temperature used. Annealed hardness. 94 to 98 HRB. Full annealing is expensive and time consuming. Should not be used, except as required for subsequent forming or specialized metal cutting operations
Hardening. Atmospheric protection rules for annealing apply to hardening. Parts must he completely clean and free of oil and shop contarnina-
Martensitic Stainless Steels / 783 tion. Thermal conductivity is significantly lower than that of carbon and alloy steels. High thermal gradients and high stresses during rapid heating may cause warpage and cracking in delicate or intricate parts. Preheat at 760 to 790 “C ( 1400 to 1455 “F). only long enough to equalize temperature in all sections. Extremely delicate or intricate parts would benetit from an additional prior preheat of 540 “C (1000 “F). Austenitize at 1010 to 1065 “C ( I850 to 1950 “F). Use upper end of range for larger sections or when maximum corrosion resistance and strength are required. Soaking time of 30 to 60 min is adequate for sections up to I3 mm (0.50 in.). Allow an additional 30 mm for each additional inch or fraction thereof. Double soaking time if parts have been full or isothermal annealed. Lncreass time by 50% if process annealed above 705 “C (I 300 “F). Quench in oil or air. Oil quenching preferred. because it guarantees maximum corrosion resistance and ductility. Martempering in hot oil or salt is suitable because of high hardenability. As-quenched hardness. approximately 56 to 59 HRC
Stabilizing.
For minimum retained austenite and maximum dimensional stability, use subzero treatment at -7-t “C (-100 k20 “F). This should incorporate continuous cooling from austenitizing temperature to the cold transformation temperature
Tempering.
Temper at IS0 to 370 “C (300 to 700 “F) for hardness of 53 to 59 HRC. Double tempering beneficial. Cool to room temperature between tempers
Nitriding. Can be nitrided to case depth of approximately (0.008 in.) in 48 h. See type 4 IO for further information
Recommended l l l l l l l l l l l l
Processing
Forge Anneal Rough machine Stress relieve Finish machine Preheat Austenitize Quench Stabilize (not mandatory. Temper Final grind to size Nitride iif required)
0.203 mm
Sequence
but beneficial)
440B: Partial Isothermal Transformation
Diagram. Composition: 0.93 C, 0.49 Mn, 0.43 Si, 18.40 Cr, 0.55 MO. Austenitized at 870 “C (1600 “F)
Martensitic Stainless Steels / 783
44oc Chemical Composition.
AlsIjUNs
(S44004):0.95IO I 20 c. I .OO
hln. 1.00 Si. 16.00 to 18.00 Cr. 0.0-l P. 0.03 S. 0.75 Mo
Similar
Steels (U.S. and/Or Foreign). AhlS 561X. 5630: ASThI A376. A3 13. A-173. A-l93. AS80; FED QQ-S-763; MIL SPEC MlL-S-862: SAE JaO5 (5 I-MO C): (Ger.) D[N I .-I 125: (Jap.) JIS SUS -1-10 C
Characteristics. Highest hardness of hardenable stainless steels. Good corrosion resistance. particularly in hardened and tempered condition. Quenched in oil or au. Can be mat-tempered. Can he full. process. or isothermal annealed. hlagnetic in all conditions. Low machinahilitj. Used for bearings, nozzles. Lake parts. and wear parts of pumps Forging. Start forging at IO-IO to I I75 “C (I905 to 2150 “F). Do not forge after temperature of forging stock drops heIon 955 “C t 1750 “F). Cool slowly from finishing temperature. Anneal Recommended Normalizing. Annealing. l
Heat Treating
Practice
Do not normalize Can be process. isothermal.
or full annealed:
Process anneal in subcritical temperature range of 675 to 760 “C t 12-U to 1400 “Fj. Use clean, rectified salt bath or an atmosphere that is compatible with this temperature range. Soaking and softening time dependent on size of kork. Air cool. Hardness. 98 HRB to 23 HRC
/sorlrertnn/ cvvrc,ll/ by heating at 815 to 900 “C ( IS55 to 1650 “F). Cool slouly to 690 “C t I275 ‘F). Hold for 1 h. Hardness. approximately 25 HRC Fdl mrrtrt~a/ at 845 to 900 “C i IS55 to I650 “F). Cool to 595 “C (I IO5 “F) at a rate not to ehceed I7 to 22 “C (30 to 40 “F) per h. After this. cooling rate has no effect on hardness. Avoid decarburization. Can use atmospheric protection in the form of a vacuum. the inert gases argon or helium (both expensive). or nitrogen. All should have dew point beIon -51 “C t-60 ~FJ. Endothermic-generated atmospheres can be used b) holding dru point in the 0.95 to 1.20 carbon range for the annealing temperature used. Annealed hardness. 9X HRB to 25 HRC. Full annealing is expenstle and time consuming. Should not be used. escept as required for s&sequent fomling or difficult specialized metal cutting operation
ln aerospace practice. parts are annealed at 900 “C (I 650 “F), then cooled to below 59.5 “C t I IOS ‘F) at a rate not to esceed 30 “C (55 OF) per h, followed by au cooling to ambient
Hardening. Atmospheric protection rules for annealing apply to hardening. Parts must be completeI> clean and free of oil and shop contamination. Thermal conductivity is significantly loher than that of carbon and allo! steels. High stresses during rapid heating may cause warpage and cracking in delicate or intricate parts. Preheat at 760 to 790 “C ( 1400 to l-155 “F), onlj long enough to equalize temperature in all sections. Extremsll delicate or intricate parts uould benefit from an additional prior
784 / Heat Treaters Guide preheat of 510 “C ( 1000 “FJ. Austenitire at 1010 to 1065 “C ( IS50 to 1950 ‘:‘FL Use upper end of range for larger s&ons or when maximum corrosion resislnnce and strength are wquired. Sonhing time of 30 to 60 tin is adequate for section> up to I3 mm (0.50 in.). .Allou an additional 30 min for each additional inch or fraction thereof. Double soakinp time if pans hair been full or isothermal annealed. Increase time b) SO%,. if process annealed above 705 “C ( I300 “FL Quench 111oil or au. Oil quenchrng preferred. because it guarantees maximum corrosion resistance and ductility. hlartempering in hot oil or salt is suitable hecause of high hardensbilitj. As-quenched hardness. approximarelq 60 to 62 HRC minimum In aerospace practice. parts are nustsnitizrd aI 1055 “C I 1930 jF). then quenched in oil or pol>msr. .Atier rhe quench. parts are immersed in cold eater to ambient temperature irater. then refrigerated at -70 “C (-95 “F) or lower for not less than 2 h
Stabilizing.
For minimum retained austsnite and maximum dimensional stahilitj. use subzero treatment at -71 jC 1-100 +20”F). This should incorporate conGnuous cooling from nustenitizinp temperature
Tempering. Temper al I65 “C (330 ‘F) or higher. for minimum hardness of 60 HRC. Temper al 190 “C (37.5 “F) for 58 HRC minimum: at 230 “C
440C:
Soak Time for Annealing and Austenitizing
(445 “F) for 57 HRC minimum: and a1 357 “C (675 “F), for hardness approximateI> 52 to 56 HRC. Double tempering beneficial. Cool lo room temperature between tempers
Nitriding. Can be nitrided (0 case depth of 0.203 mm (0.008 in.) in 18 h. See type -I IO for further information
Recommended l
Forge
.
.4MCl1
Processing
l Rough machine . Stress relke l Finish machine l Preheat l Ausknitize l Quench l Stabilize (not mandator!, l Temper l Final grind to size l Nitride lif required)
but beneficial)
(Aerospace Practice) Minimum soali
Thicknesc(a)
Tie in.
mm Up to 5 s tll I5 15m25 3
Id 10
40 w so so to 65 65 IO 75 75 to 90 9om loo 10010 I I5 115tol2.5 I25 111xxi O\er 200
ia, ThlAn~ss is rhe nunimum
Over O\er Oler O\rr O\cr O\er O\er Oter Oker Over O\er
Up IO O.Xl 0 250 10 0.500 0.500 10 I.000 I.000 10 I 500 I.500 to 2.000 2.000 10 1500 2.500 10 ?.(Hx, 3.000 10 .l.500 3.500 10 1.000 1.000 10 -I 500 -1.500 h3 5.000 5.000 to 8.000 Ob er Y 000
Sequence
(b,c.d.e,fJ h
hlinimum
air or almosphere min
h
salt min
25
18
~j
35 10 15 SO 55
I I I I 2 2 2 7
IS 30 -15
; 3
30
(U
soak
Time (b,c.d,e$J
1’; 30 -Is I ! I I I I th)
5 IO I5 20 40
dimension of the hea\ lest seCtion of the p;ut. (b) Soaking shall comnwnse Mhen all control. indicaring. and recording rhemlocouplrs reach the specitied set temperature. or if load rhermocouplcs arc used, n hen the part temperamre reaches rhe minimum oilhrt iumscr uniformity tolerance ar Ihe set lempenture. Parts coated with iopperplale or similar rcHesC\e coatings that tend to retlect r&ant hea1 shall hate theirswting tinw increased b! At IeasSt504. unless load thermocouples me used.(c) When load ~hemlocouples ax usrd. the soaking ume shall be not less than 30 min. td, In all case\. rhe p;uts shall be held for suliicient lime to ensure that the cemrr of the most massive area has reached temperature and the nccessq transformation and diffusion hate taken place. (e) hlnximum soak time shall be tirice the minimum specified. except for subcritical annealing. I I‘, Longer times ma\ be necebrw for pluts R ith complex shapes or part> that won’t heat uniformly. I g) -I h hour plus 30 min for e\ery 75 mm (3 in.). or portion therenf greater Lhan XOmm (8 in.,. th) 2 h plus 20min forc\srl, 75 mm f3 in.). or portion thereofgreater than ?OO mm (8 in ). Source. AhlS 2759/S
Martensitic
Stainless Steels / 785
440C: Hardness vs Tempering
Temperature. Composition: 1.02C.0.48Mn,0.017F!0.011 S0.18Si.0.54Ni. 16.90Cr,0.64 MO. Heat treated at 1040 “C (1905 “F), 2 h. Oil quenched from 66 to94”C (150 to 200 “F). Double stress relieved at 175°C (345°F) 15 min. Water quenched. Tempered 2 h. Heat treated, 9.78 mm (0.385 in.) round. Tested, 9.53 mm (0.375 in.) round. At 260 to 540 “C (500 to 1000 “F). Also, heat treated, 14 mm (0.550 in.) round. Tested, 12.8 mm (0.505 in.) round. At295to760 “C (1100 to 1400 “F). Source: Republic Steel
440C: Microstructures.
(a) Vilella’s reagent, 500x. As forged. Large primary carbide particles. Heavy carbide precipitation at grain boundaries. Secondary carbide particles. Matrix predominantly retained austenite. (b) Vilella’s reagent, 500x. Forging annealed at 870 “C (1600 “F). Furnace cooled to 94 “C (200 “F) in 48 h. Air cooled. Large particles of primary and spheroidized particles of secondary carbide. Ferrite matrix. (c) Vilella’s reagent, 500x. Forging hardened by austenitizing at 1010 “C (1850 “F), 1 h. Air cooled. Tempered at 230 “C (445 “F), 2 h. Large primary and tempered secondary carbide particles. Martensite matrix. (d) Vilella’s reagent, 100x. Forging, hardened and tempered. Band of carbide segregation. Dispersed carbide particles. Tempered martensite matrix. Microhardness indentations (black). Shows relative hardness of carbide particles and matrix. (e) Super picral, 500x. Bar, preheated at 760 “C (1400 “F), !$ h. Air cooled to 66 “C (150 “F). Double tempered at 425 “C (795 “F), 2 h each. Primary and secondary carbides, light islands and particles. Tempered martensite matrix. (f) Vilella’s reagent, 200x. Ear, austenitized at 1010 to 1050 “C (1850 to 1920 “F). Oil quenched. Tempered at 190 “C (375 “F). Segregated stringers of primary carbide (light) and dispersed secondary carbide particles. Tempered mat-tensite matrix
Cast Stainless
Steels
Introduction The heat treatment of stainless steel castings follous closely in purpose and procedure the thermal processing of comparable wrought materials. However, the differences in detail warrant separate consideration. In work-hardenable ferritic alloys. machining and grinding stresses are relieved at temperatures from approximately 260 to 5-tO “C (500 to 1000 “F). Castings of the martensitic grades CA-IS and CA-JO do not require subcritical annealing to remove the effects of cold working, because they are not cold worked or cold formed. Casting stresses in other martensitic grades should be relieved by subcritical annealing, before further heat treatment. For hardened martensitic castings, the stress-relieving temperature must be kept below the final tempering or aging temperature. Homogenization. Alloy segregation and dendritic structures may occur in castings. They may be particularly pronounced in heavy sections. Also. mechanical reduction and soaking treatments are required in the mill processing of wrought alloys. Therefore. it is frequently necessary to homogenize some alloys at temperatures above 1095 “C (2005 “F). to promote uniformity of chemical composition and microstructure. Full annealing of martensitic castings results in recrystallization and maximum softness. but it is less effective than homogenization in eliminating segregation. Homogenization is a common procedure in the heat treatment of precipitation-hardening castings. Ferritic and Austenitic Grades. The fenitic. austenitic, and mixed ferritic-austenitic grades are not hardenable by heat treatment. They may be used in the as-cast condition. if maximum resistance to corrosion is not required. They can be annealed or stress relieved to improve their corrosion resistance and machining characteristics. The fenitic alloys CB-30 and CC-50 are annealed to relieve stresses and reduce hardness by being heated above 790 “C (1455 “R. as shown in the table included in this section. The austenitic grades achieve maximum resistance to intergranular corrosion by the high-temperature heating and quenching procedure known as solution annealing. As-cast structures or castings exposed to temperatures in the range from 425 to 870 “C (795 to I600 “F) may contain complex chromium carbides precipitated preferentially along gram boundaries in wholly austenitic grades. This microstructure is susceptible to intergranular corrosion, especially in oxidizing solutions. In partially ferritic grades. carbides tend to precipitate in the discontinuous ferrite pools. Thus, these grades are less susceptible to intergranular attack. The purpose of solution annealing is to ensure complete solution of carbides in the matrix and to retain these carbides in solid solution. Solution annealing procedures for all austenitic grades are similar. They consist of heating to a temperature of approximately 1095 “C (2005 “F). holding for a time sufficient to accomplish complete solution of carbides. and quenching at a rate fast enough to prevent reprecipitation of the carbides, particularly while cooling through the range from 870 to 540
“C (1600 to 1000 “F). Temperatures to which castings should be heated before quenching vary somewhat. depending on the alloy. As shown in the table included in this section, a two-step heat treating procedure may be applied to the niobium-containing CF-8C alloy. The fust treatment consists of solution annealing. This is followed by a stabilizing treatment at 870 to 925 “C ( I600 to 1695 “F), which precipitates niobium carbides, prevents formation of the damaging chromium carbides, and provides maximum resistance to intergranular attack. Because of their low carbon contents. CF-3 and CF-3M do not contain enough chromium carbides to cause selective intergranular attack and hence do not require solution annealing. Martensitic Grades. The hardening procedures for CA- IS castings are similar to those used for the comparable wrought alloy, type 410. Recommended practice for annealing. austenitizing, and tempering CA-15 are in the article on this alloy which follows. In addition, operating information on two other martensitic grades. CA-40 and CA-6NM. is presented in articles. CompositiOns. Alloy Casting Institute (ACI) compositions for corrosion resistant cast steels are in the adjoining table, along with information on comparable wrought, and ASTM grades, plus the most common end-use microstructure for each alloy. In addition. I5 articles on representative individual alloys are presented. They include: Ferritic and Austenitic grades CB-30 CC-SO CE-30 CF.3 CF-IC CF-BM blartensitic CA-IS CA-40 CA-6NM
CF-12M CF- I6F CF.20 CM-20 CK-20 CN-7M
grades
Applications and welding listed in adjoining tables.
conditions
for corrosion
resistant alloys are
Heat-Resisting Grades. Information on these casting alloys that follow include AC1 compositions; general corrosion characteristics and creep stress values: room temperature properties: short-term tensile properties at elevated temperatures: approximate rates of corrosion in air and flue gas; and corrosion resistance at 980 “C ( I800 “F) in various atmospheres.
Cast Stainless
ACI Type: Steels
Compositions wrought
ACltype
alloy type(a)
Chromium steels CA-IS 110 CA-I5M 320 CA-I.0 CA--lOF 431.4-E CB-30 cc-so 446
and Typical
ASTM specfications
A743.A217,A187 A 733 A 743 A 713 A 743
Microstructures
Most common end-use microstructure
of Alloy Casting
C
0.15
A 743
Martensite Martensite Martensite Martensite Ferrite and carbides Ferrite and carbides
0.15 0.10 0 ‘-0.1 0.30 0.30
A743 A 713. A187 A7.l3
Rlartensi te Martensite hlartensite
0.06 0.06 0.20-O 28
A747
hlartensite.
age hardenable
0.07
CB-7Cu-2
A747
Martensite.
age hardenable
CD-IMCu
A351,A743.A744. A 890 A 713 A351.A7-l3,A7U
Austrnitc in ferrite. age hardenable Femtr in austenitr Ferrite in austenite Ferrite in austenite Ferrite in austenite Ferrite in austenite Ferrite in austenite Ferrite in austcnite Ferrite in austenite Femte in austenite Femtr in austenitr Ferrite in austcnite Femtrt in austemte or austenite Austcoitr Austenite Ferrite in austenitc
Chromium-nickel CA-6N
I
(X-30 CF-3(e)
CF-3M(eb CF.3MN CF-8(e) CF-8C CF43hI CF-IO CF- IOM CF-IOMC CF-IOSMnN
312 304L 316L 30-l 317 316
CF-I2M
316
CF-16F CF-20 CC-6hlhfN
303 302
CG-8M CG-I2 CH-8 CH-IO CH-20 CK-3hlCuN
317
CK-20
310
Nickel-chromium
steel
CN-3M CN-7hl
CN-7MS CT-ISC
1.00 1.00 1.00 100 I .OO 1.00
Si
(ACI) Corrosion-Resistant Composition, Cr
Cast
S(b) Ni
Others(c)
I.0
O.SOMo(d)
I.0 I .o I .O 2.0 -I.0
0. IS-I.OOMo
I.90 065 I.50 I.50 I.50 1.50
I I.%l-l.0 11.5-11.0 11.5.IJ.0 II.S-14.0 18.0-72.0 26.0-30.0
I .OO I.00 I .OO
10.5-17 5 11.9-11.0 11.0-125
6.0-8.0
0.70
I .OO
15.5-17 7
3.6-1.6
0.07
0 70
loo
l-3.0-IS.5
1 s-s.5
0.04
I .(X1
I.00
25.0-26 5
4.75-6.0
I so I so I.50 I .so I.50 I.50 I so I 50 I.50 I so 7.00-9 00 I .50
2.00 ‘00 2.00 1.50 2.00 2.00 2.00 2.00 I.50 I 50 3.50-4.50 2.00
26.0-30.0 l7.0-‘I.0 17.0.‘I.0 17.0-z I .o 18.0-2 I .O 18.0-21 0 l80-Il.0 180-21.0 18.0-21.0 15.0-18.0 lhOl8 0 I8 O-21.0
8.0. I I .O 8.0-13.0 8.0-12.0 9.0- 13.0 8.0. I I .O 9.0-12.0 9.0- 12.0 80-11.0 9.0- I2 0 13.0-16.0 8.0-9.0 9.0-12.0
I.50 I.50 1.00-h 00
‘.oil 200 I .OO
18.0-21.0 18.0-2 I .O 20.5-23 5
‘).(I- 12.0 8.0-I I .O I 1.5-l 3.5
I .50 I 50 I.50 I.SO I.50 1.20
I.50 2.00 I .50 2.00 2.w I SM
IY.O-21.0 20.0-23 0 22.0-26.0 22.0-26 0 22.0-7-6.0 19.5-20.5
9.0- 13.0 l(J.O-I3 0 12.0-15.0 12.0-15.0 I2.0- IS.0 17519.5
2.00
2.00
23.0-27.0
19.0-22.0
20 O-12.0 19.0-X 0 I8 O-20.0 19.0-Z I .o
13.0-27.0 17.5-30.5 22 o-3.0 3 I .o-34.0
O.SMo(d)
steels
CA-6NM CA-28MWV CB-7Cu-
hltt
Institute
Steels / 787
A351.A743,A744 A 743 A351.A743,A711 A3Sl.A7-13.A744 A351,A743.A744 A351 A351 A351 A351.A743
A 743 A713 A35l.A743
A351.4743.A7U A 743 A351 A3Sl.A7-l3 A3Sl.A7-13.A7U
Ferrite in austenite Ferrite tnaustenite Ferrite in austenitc Ferrite in austrntte Austrnite Ferrite tn austenite
A 713
Austetute
A 7-13 A35l,A713.A7-U A 713. A 7-U A351
Austenite Austenite Austenite Austenitr
A3.51 309
0.30 0.03 0.03 0.03 0.08 0.08 0.08 0 04-O. IO 0.04-O. IO 0. IO 0.10 0. I 2 0.16 0.20 0.06
0.08 0.12 0.08 00-1-o IO 0.20 0.025 0.20
0.03 007 0.07 0.05-O. IS
0.50 loo O.SO- I .oO
XKJ I.50 I so 0.15-1.50
I.00 I..50 3.501,gr 0.m I .so
3.5-4.5 0.50-I 00
0.4-I .OMo ‘.. 0.9-I .25Mo: 0.9- I .25W: 0.2-0.3v 2.S-3.2Cu;0.20-0.3SNh: O.OSN max 2.S-3.3Cu:0.20-0.3SNb: 0.05N max I 752.2Shlo: 2.75.3.2SCu
2.0-3.OMo 2.0-3.OMo:
0. IO-EON
NMf) 2.0-3.Ohlo 2.0-3.OMo 1.75-2.25Mo 0.08-O. I8N 2.0.3.Ohlo I .SOhlo max: 0.20-0.3SSe I SO-3.OOhlo: 0. IO0.30Nb; 0. IO-30V; 0.20~-ION 3.01.0hlo
6.0-7.OV: 0. I8-0.24N: o.so- I OOCU
-155Shlo 2.0-3.OMo: 2.s-3.OMo: 0.5-l sv
3 03.OCu I .s-XCU
(a) ‘Qpe numbers of wrought alloys are listed only for nominal identification of corresponding wrought and cast grades. Composition ranges of cast alloys are not the same as for corresponding wrought alloys; cast alloy designations should be used for castings only. tb) hlaumum unless a range is given. The balance of all compositions is iron. (c)Sulfur content is 0.04% in all grades except: CG-6hlMN. 0.030% S (mast: CF-IOSh4nN. 0.035, S tmax): CT-ISC. O.O3c”c,S (ma\): CK-3hlCuN. O.OlOQ S (max): CN-3hl. 0.0306 S (m~):CA-6N.0.0206S(max):CA-28hlWV.0.03O~~S(m~):CA-U)F.0.20-O10~S:CB-7Cu-I and-2.0.03%S(ma~.). Phosphoruscontent isO.O4%~max~inallgradesexcept. CF-l6F. 0.176 P (max); CF-IOSMnN. 0.060%, P rmax): CT-ISC. 0.0304 P tmax): CK-3hlCuN. 0.045~ P tmax): CN-3hl. 0.03Oc1 P (mar): CA-6N. 0.0204 P tmax): CA28MWV. 0.030% P (max): CB-7Cu- I and -2.0.0354 P (mrlr;). td) Molbbdenutn not intrnoonall) added. or) CF-?A, CF-3MA. and CF-8A have the same composition ranges as CF-3, CF-3hl. and CF-8. respectively. but habe balanced compositions so that ferrite contents are at Ie\els that permit higher mechanical property specifications than those for relatedgrades.Theyareco~ered by ASTM A 351. [f) Nb. 8 x %,C min (l.O%, maxi: or Nb+Ta x QC t I. Iq, max). (g) For CN-7hlS. silicon ranges from 2.50 to 3.50%,
788 / Heat Treaters
Summary
Guide
of Applications
for Various
Corrosion-Resistant
Cast Steels Characteristics
AllO)
c4-I5 CA-40 CA-6Nhl CA-6N CB-30 CB-7Cu- I CB-7Cu-2 cc-so CD-4hlCu CE-30 CF-3. CF-8. CF-‘0. CF.3hl. CF-BM.
CF-YC.CF-I6F CG-Yhl CH-20 CK-20 CFu-7hl
Welding
H’idrly used in mildI! corrosilr en\ ironmrnts: hardcnahlc: good eroston resistance S~milartoCA-15at higherstrength Ic\el lmproied proper&> o\er CA IS. especialI) impro\rd resistance rocaitxion Ourjtanding combinations ofa=ngth. ~oughnesi. and #eldahiltv u ith moderateI! good corrosion resistance Improved performance m oxidizing eni ironmentb compared to CA- 15: excellent resistance to corrosion b! nitric acid. alkaline solutions. and many organic chemicals Hardrnahls H ith good corrorion resistance Suprnor combination of strength. toughness. and ucldabili~ 1%rth moderateI! good cormston re+ance Used in highl) owbring medtaihor HNO,. astd nunc \raterst Similar to CF.8 in corrosion resistawe. but higher svrngth. hardness. and stress-comosion cracking resistance: txrllent resistance to en\ ironments rn\ol\ ing abmston orerojion-coTToj1on: usefully employed in handling hoth oxidizing and reductng cormdents SimilmtoCC-50. but Ni imparts higher strength and roughness level>. Agmde a\ilahlc with controlled ferrire CF types: most wtdrly wed corroston-reststant alloys at ambient and cr)ogemc temperatures hl !anations: enhanced resistance to halogen ion and redwing acids C and F \ xiations: wed \t here application does not pemtit posnrcld heat treat .Agradessvailsble M ith controlled femte Greater resistance to pitting and corrosion in reducing media than CF-8hl: not suitahlr for nitric acids orothrrstrongl) ovidring environments Superior to CF.8 in specialized chemical and papsrnpplication~ in resistance IO hot HJSOI. org.+ acids. and dilure H+SO,. rhe high nickel and chromium contents also make thus alloy less susceptthle to tntergranular conosion after exposure to carhtde-precipitstng trmpcrarures improved corroston wsistance compared to CH-20 HighI) resistant to H,SO,. H xPO,. H&GO,. salts. and seawater. Good resistance to hot chloride -11 solutions. mtric acid. and many reducing chemicals
Conditions
ACI
for Corrosion-Resistant
Preheat
Pw of
designation CA-6Nhl CA-15 CA-40 CB-7Cu CB-30 cc-so CD-4hlCu CE-30 CF.3 CF.8 CF.YC CF-3hl CF-8hl CF-I2hl CF-IhF CF-20 CG-YM CH-20 CK-20 CN-7hl
electrodes used(a)
T
Same composition 410 -I IO or 120 Same compoiition or 308 442 446 Sdmc conipo>tllon 312 308L 308 347 316L 316 316 308 or 308L 308 317 309 310 320
100-150 XX-315 2(x)-3 I5
Note: hletal arc. inert-gas arc. and electroslng
Section thickness, mm (in.)
are recommended
Poshreld heat treatment 590-620 “C I I 100. I I .50 ‘n 610-760”CtII2S-IXX)‘~F1.lurc~~~l 610.760°C I II25-lUW’Fj,iurcool SO-590 ‘T I YOW I IOU “Fj. air cool 790 ‘T ( I-150 “FI. nun. atr cool ‘900°C I I6iO”Ft. arc001 Heat to 1120°C tIO5O”F). cool to ItUO”C ( IYOO ‘F). quench Quench from I OW I I20 “C i2OOO-20.50 “F) Llsuall~ unneccssag Quench from I t2-0 I I20 “C I I YOO-2050 “F)
Not requtred
Nor Not Not Not Not Not Not Not Not Not Not Not Not
requtred rrqwred required requtred required required required required required required required required required
700 \t elding methods can be used. Sugared
2.1t3h:l 3 2l’b) 1.01j.3~1 -1.8 13.,(4 6.4 I I., I elrctrodcj
OF
315-42s 20@7OO
Electrode diameter, mm (in.)
3.2-6.4 t ‘!+‘,i) 3.2-6.-l (!i-‘,il 3.1-6.4 I ‘&,) 6.4-I 3 I’s,-‘,;) ?13t’.!) t;11 Lime-
Steel Castings
llsudl~unnrsrssq
-UN electrical
hIidl)
uM+XSSLUJ
Quench Quench Quench Quench Quench Quench Quench Quench
from from from from from from from Tom
ssrttngs and electrode
Current. A 45-70 70. I05 100-140 I 30- 180 110-290
rircj
1070-I 150°C 1070-I ISO’T IOYO- I I.50 “C IOYO- I I50 “C IWO-I 110°C IOYO- I ISW’C I @X1- I I80 ‘C I 120 ‘T t2050
for \ arious wctton
t lYS@1100°F~ (IYSO-2100°F) (2000-2 100°F) t X00-2 IO0 “FJ t IYW20SO”Ft (XXI-2lOO’F) (X00-2 I SO “F) “F)
thicknesses
arc:
hbximum m voltage, V 2-l 25 15 ‘6 ‘7
Compositions AC1 designation HA HC HD HE HF HH HI HK HKSO HKU) HL HN HP HP-SOH’Z(s) HT HI-30
of ACI Heat-Resistant UNS number 19’605 193005 JY 3403 JY2603 593.503 JY4003 JY127-I
J946O-t J942 I.3
194605
HlI HH HX
Casting
Cast Stainless
Steels / 789
Alloys Composition,
S(b)
ASTM specfications(a)
C
Cr
Ni
Si (max)
A217 A197.A608 A ‘97. .A608 A297.A608 A2Y7.A608 4 297. ,460x. AU7 A’Y7.AS67.A608 A 397.435 I. AS67. A608 A351 A351 A297.A608 A:Y7,A608 A 197
0.20 max 0.50 mab 0.50 max 0.10-0.50 O.‘O-0.40 0.~0-0 so 0.20-0.90 0.70-0.60 0.25-0.3s 0 35-0.4s 0.10-0.60 0.~0-0.50 Cl 35-0.7s 0 -Is-o.ss 0.35-0.75 0.2%0.35 0 354.75 0.50.75 0.35-O 7s
8-10 26-30 26-30 26-30 IY-23 21-28 26-30 2-l-28 23.0.17.0 23.0>27 0 28-32 19-23 24-28 24-28 13-17 13.0.17.0 17-21 10-l-t IS-19
4 ma\ 4-7 Y-II Y-12 II-11 14-18 18-22 19.0-22.0 lY.0.110 18-22 23-27 33-37 33-37 33.37 33 O-37.0 37-41 58-62 M-68
I .Oo 2.00 l?.ca 2.00 1.00 1.00 2.00 2.00 I .7s I .7s XKI 2.00 2.ocl 2.50 7.SfJ ?.S(J 2.50 ‘SO 2.50
A297.A3Sl.AS67.A608 A3SI A297.A608 A 297. A608 A297.A608
(a) ASTM deslgnatlons are the same as ACI desipattonl. th t Rem Fe in dl compositions. hlanpanesc content: O.R.‘, to 0.65 5 for HA. 15 for HC. I .Sq for HD. and 2% for the other alloys. Phosphorusandsulfurcontents: 0.04% tmax) forall hut HP-SOkVZ. hlolvhdenum is tntentionally addcdonl) to HA. u hish hat0.90 to I 70% hlo: maximum forotheralloys issrtatO.S% MO. HHalsocontainsO.2rL Ntmaxt tcjAIsocontains1to65 W:O.I to I.OQ~Zr.andOO35% Slma~land Ptmax,
General Corrosion Characteristics Indicated Temperatures
of Heat-Resistant
Cast Steels and Typical
Limiting
Creep Stress Values at
Creep test temperature Alloj
Corrosion characteriskzs
HA HC
Good oxidation resistance to 650 “C ( 1200 “F): w idrIb used in oil refining industq Good sulfur and oxidation resistance up to IOYS “C I 2OUO “F); minimal mechanical propertws: used in applications where stwngh is not a consideranon or for moderate load lwanng up to 6S0 “C t I200 “F, Ebcellrnt oxidation and sulfur resistance plus \\sldahili~ Higher temperature and sulfur resistant capabilities than HD Excellent general corrosion resistance to 8 IS “C i IS00 “FI H ith modcrate mechanical propcntes High suengh: oxidation resistant to I090 “C (2000 “F,: most \5 idcly used
HD HE HF HH(a) HI HK
HL HN HP HP-SOWZ HT
HU HU
HX
ts~Tlrogrades:
lmprotrd owiation resistance compared to HH Because of itzi high temperature strength. uldely used for strw.ed parts in sbuctural spphsatton> up to I IS0 “C (2 I(x) “F): offers good reslstance to sorrosion h) hot ga.w>. mcludmg wlfurbearing gases. in hoth oxtdizing and reducing conditions (although HC. HE. and HI are more resistant in oxidizing gasej): used in illr, ammonia. hydrogen. and molten neutral salt\: m Idell used for tubes and furnace parts Improved sulfur resistance compared to HK: cspeciall! useful \\ here ewrssi\e ,caline must br a\ aided Very high strength at high temperatures. resibtant tooxtdizing and reducing flue g&e\ Resistant to both oxidizing and carhuririnp atmospheres at high temperatures lmpro~edcrecpmpturcstrrngthat lO9C”Ct~000”F1andaho\ecomparcdtoHP H’idely used in thermal shocb applications: corrosion resistant in atr. okidizing and redwing flue gases. carburizing gases. salts. and molten metals: performs satisfactorily up to I I SO “C tZIOO”F, in ohidiling atmospheres and up to IO% “C (2000 “FI in reduang atmosphere>. provided that limiting creep stress \alurs are not exceeded Higher hot strength than HTand ohen selected for its superior corroston resIstawe High hot strength and clectrkal resisti\ Ity: performs satisfactotil) to I I70 “C I 20.50 ‘FI in strongly oudizing atmospheresand up to IWO “C I 1900 ‘FI inoxidizing or reducmg product, ofcombustion that do not contain sulfur: resistant to some 4ts and molten metal< Resistant to hot-gas corroilon under qcling conditions u hour cracking or \t arpmg: corroston resistant in air, carhurizing gases. combustion gases. flue gases. h)drogcn. molten qanide. molten lead. and molten neutral sahsat temperatures up to I ISO”C I 2 IOWFI type l~frmtr~naustemt~)nnd~)~~
Il~uholl!
austrnitickperASThlAU7
T
Limiting creep stress (0.ooo1 a/h) hi MPa
OF
650 870
I200 1600
21.5 S.15
3.1 0.75
981) 980 870 980
1800 I 80 16(x) IS00
0.9
9x0
I800
I .4 3.9 I.1 (typeI) ?.I (type II) I .9 I .1
IWO
I900
6.2 9.S 27 7.5 (type I) 11.5 (Iype II) I3 95
Y8tI
Id00
IS
2.1
IO.40 980 IWO 080
I YW I800 YJfx) I800
II 19 1.x l-l
I6 2.8 0.7 2.0
IS 9.5
2.2
II
1.6
980 980
Y~(J
IX00
I .-I
790 / Heat Treaters
Guide
Typical Room-Temperature
Properties
of ACI Heat-Resistant
Casting
Alloys
Tensile strength MOY HC
MPa
ksi
MPa
ksi
AS-C3St
760 790 585 655 620 635 690 585 595 550 635 SSO 620 515 58s 56.5 470 190 48.s 51s 485 SO5 470 580 450 SO5
110 11s
51s 550
75
85 95 90 92 100 85 86 80 92 80 90 75 85 82 68 71 70 75 70 73 68 8-l 65 73
330 310 380 310 3-E 31s 380 27s 310 310 -IS0 3-E 315 3bO 2bO 275 27s 310 27s 295 250
Aged(a) As-cast As-cast Aged(a) As-cast Aged(a) As-cast Aged(a) As-cast Aged(a) As-cast Aged(a) As-cast Aged(b) As-cast As-cast As-cast As-cast Agedib) As-cast Aged(c) As-cast Aged(d) As-casr Aged(c)
HD HE
HF
HH.t)pel HH. type Ii HI HK
HL HN HP HT HLI HH
w
Yield strength
Condition
tar Agingtreatment: 24hat 76O”Ct 1400°F). fumacecool.(b)Agingtrearment: treatment: 18 h at 980 “C ( I800 OF). furnace cool
Representative
Short-Term
Tensile
Properties
30s 24hat760GC(I-KW”F~,aircool.
223 90 200 270 165 190 I85 200 I80 200 I80 200 170 I90 I92 160 170 I80 200 170 I90 I85 205 176 I85
IO I9 13 II IQ 5 9 5 4 4 9 9
t~)Agingtreatment:
-l8 hatYgO”C(
at Elevated
Temperatures
Alloys
Eardll~ ml
19 18 I6 20 IO 38 25 ‘5 II 1s 8 I2 6 I7
80 -la 45 55 45 SO SO 55 40 4.5 35 65 SO 50 52 38 10 10 4s 30 13 36 5’ 36 4-l
360 250
of Cast Heat-Resistant
Elongation. %
18OO”F),aircool.(d)Aging
Property at indicated temperature (1JOO~F) Ultimate tensile Yield strength at strength 0.2 % offset Elongation, MPa ksi hfPa ksi 5% 760%
Alloy HA HD HF HHttjpeI)(c) HH (type IIMsI HI HK HL HN HP HT HlI HH’ Hx
4662(a) 248 262 228 258 262 258 345
6-h~
296 240 ‘75 220 310(d)
43 35 -lo 32 -lStd)
36 38 33 37.4 38 31.5 so
(31 In tlus instance. test temperature
220(b) ,_. 17’ 117 136
32t bj _._ 25 I7 19.8
I68
21.1
;; I6 I8 I6 6 I2
200 I80
29 26
IS IO
I58 138(d)
13 20(d)
was 5-lO”C I 1000°F)
8(d)
870 “C (1600 “F)
Ultimate tensile strength hIPa ksi I59 I15 I27 1-M 179 lb1 210 I40 179 130 I35 I31 I11
(b)Test tcmperxure
‘3 21 18.5 21.5 26 23 30.5 ‘0 26 I9 19.5 19 20.5 uas 590°C
!BoT
Yield strength at 0.2 5%o&t hiPa ksi ,:: 107 93 II0
Elongation, 8
IOI
,,_ IS.5 13.9 I6 ” I5
I8 I6 30 I8 I2 lb
100 I21 103
11.5 17.5 I5
37 27 2-l 20
103 I21
I5 17.5
I IO95 “F). (c~npe
Ultimate tensile strength
48 land Il perASTh1
hlPa
bi
ld; ___ 62 75 _.. 8.53 I29 83 loo
IS .., 9 IO.9 ,, 12.4 18.7 I2 I-l 5 II IO IO 10.7
76 69 69 7-1 AU7
(d)Trst
(MooT)
Yield strength at 0.2% of&et hlPa ksi ::: .,. 43 SO .,. 60 ,,. 66 76 55 43 55 17
Elongation, +
::: ___ 6.3 7.3 .., 8.7 ___ 9.6 II 8 6.2 8 6.9
tempennrrew~6650”C(1200°~
40 __. 45 31 42 .__ 51 46 28 28 40 30
Cast Stainless
Approximate
Rates of Corrosion
for ACI Heat-Resistant
Casting
Alloys
870 oc
HB HC HD HE
HK HL HN HP
HT HU HIV HX
6.25I .25 I .250.631.25+ 0.630.‘5+ 0.250.630.25+ 0.63 0.25+ 0.250.25O.‘S-
of Ferritic and Austenitic Minimum temperature OF YI
For full softness CB-30 cc-50
CF-SM.CF-I?M(e) CF- l6F, CF-20 CH-20 CK-20
CN-7M
12.5 I.25 I .250.882.5 I.25 0.880.880.88 I .25I.35 I.25 0.880.88 0.88-
Stainless
Quench(a)
I-IS0 1450
3.5+ 0.630.630.63I .25+
1040 I040 I040 I040 1095 1095 II20
1900 1900 1900 I900 2000 mlo 2050
W.0.A W.0.A W.O.4 W.0.A W.0.A W.0.A W.0.A
97 77 77 80 77 88
W.0.A
69
76
Oxidizing
12.5 0.63+ 0.630.63XC O.b3 0.630.630.630.630.630.630.630 630.63-
O.b30.630.630.630.630.630.63 0.630.63 0.63-
Tensile strength ksi(b) MPa(b)
95 97
Reducing
6.25 0.63 O.630.63l.25+ 0.63 0.630.630.63 0.63 0.63063 0.63I .250.63-
Reducing I2.5 0.630.630.636.25 0.630 630.630.630.63 0.632.5 0.63 6.25 0.63-
Corrosion Resistance of Heat-Resistant Cast Steels at 980 “C (1800 “F) in 100 h Tests in Various Atmospheres
Steel
FCtA(c, A
2.3 g/m’
0.12 g/m’
Oxidizing
Alloy 790 790
For maximum corrosion resistance 1095 2ooo CE-30 CF-3. CF-3M CF-8. CF-SC(d)
109OT
~2~ OF)
~~~“F)
0.630.25 0.25 O.l30. I30. I3O.l30.250.25+ 0.13 0.630.13O.l3O.l3O.l3-
HF HH HI
Annealing Castings
980 oc
(lm°F)
in Air and in Flue Gas Corrosion rate.mm/yT,at 980% (1WJ’F) in flue gas with sulfur content of:
Oxidation rate in air, mm/yr Alloy
Steels / 791
655 669
bb9 531 531 552 531 607 52-I 476
(a) FC, furnace cool; W. water. 0. oil: A. air. (b) Approximate. (c) Furnace cool to 5-tU “C (IOOO”F); then air cool. (d)CF-SC may be reheated to870 to925 “C (16OOto I700 “F): then air cooled for precipitation of niobium carbides. (e) CF.I2M should be quenched from a temperature above I095 “C (2000 OF).
HA HC HD HE HF HH HI HK HL HN HP HT HU HW’ HX
Corrosion rating(a) in indicated atmosphere Reducing Reducing flue flue gas gas cooled to Oxidizing Reducing Reducing (constant 15OT (3oo~F) Air flue gas(b) flue gas(b) flue gas(c) temperature)(d) every I2 h(d) U G G G S G G G G G G G G G G
u G G G G G G G G G G G G G G
11 G G G S G G G G G G G G G G
u s S
U G G
U S S U S U G U u U S
S G G
tat G. good (corrosion mte r < 1.27 mnuyr. or 50 mils/yr); S. satisfactory (r c 2.5-l mndyr. or 100 milslw): U. unsatisfacton tr > 2.54 mm/yr. or 100 mils/yr). (b) Contained 2gofsulfur/mr(S grinsS/ICO ft’j. (c)Contamed 120gS/mJ(300grainsS/IO0 ft’t td~Contained-10gISlnt~ilOO~~insS/lOO~~
792 / Heat Treaters
Guide
CA-6NM Chemical
Composition. AC1 CA-6Nhl: 3.5 to 4.5 Ni. I I.5 to l-1.0 Cr. 0.1 to I .O hlo
0.06 C. I .OOhln, I .OO Si.
Similar
UNS JY1540: ASTM ,471~.
Steels (U.S. and/or
Foreign).
CA-6NM: Influence of Tempering Temperature on Hardness. Source: ESCO Corporation
A-187
Characteristics.
Recommended
hlartensitr
is most common
Heat Treating
end-use microstructure
Practice
Annealing. For maximum softness. parts are annealed at 790 to 8 IS “C (l-155 to I SO0 OF). The typical ultimate tensile strength ohtaincd is approximately 550 hlPa (80 ksi) Austenitizing and Tempering. Follou inp austcnitizing. parts arc quenched in oil or air. In austcnitizing at YSS to 980 “C t 1750 to 1795 “F) and tempering at 595 to 610 “C (I IO5 to I IS0 “F). a typical ultimate tensile strengths of approximately 835 hlPa ( I10 ksi J is obtained
CA-6NM: Effect of Tempering Temperature on Mechanical Properties of Standard Keel Block. Source: ESCO Corporation
Cast Stainless
Steels / 793
CA-1 5 Chemical
Composition.
AC1 CA-15 0. IS C. I.00 Mn, I .SO Si. I .O
Ni, I I.5 lo 14.0 Cr. 0.50 MO (not intentionally
Similar
Steels (U.S. and/or Foreign).
type 3 IO stainless: ASTM
Characteristics.
Recommended
CA-15: Effect of Tempering Temperature on Typical Room Temperature Properties
added) LINS
J9llsO;
wrought
A713. Al 17. A187
Martensite is most common end-use microsuucture
Heat Treating Practice
Annealing.
For maximum softness, parts are annealed at 8.45 to 900 “C ( IS55 to I650 “F). The typical ultimate tensile strength obtamed is approxlmately 550 MPa (80 ksi)
Austenitizing and Tempering. Following austenitizinp. parts are quenched in oil or air. Tempering al 370 to 595 “C (700 to I IO5 “F) is not recommended because in this range impact ductil!? is low. For this alloy. pans are held at austenitizing temperature for a mnumum of 30 min. In austenitizing at 975 to 1010 “C (I695 10 I850 “F) and tempering at 370 “C max (700 “F) max. typical ultimate tensile strengths of npproximatelv 1380 MPa (200 ksi) are obtained. while in austenitizing at 95 to 1010 ‘C ( 1695 to I850 “F) and tempering at 595 to 760 ‘C ( I I OS to 1400 OF), typical ultimate tensile strengths of approximateI) 690 to 930 hlPa ( 100 to I35 ksi) are obtained
CA-15: Effects of Four Methods Specimens
of Heat Treatment
were taken from shell mold cast keel blocks;
Trzaunent I Homogenize: I hat IaU,~C~l9OO~F~.AC Solution anneal. ‘+ h at 955 “C I I 7SO‘FL OQ Ternper: 3 h aI 300 “C (575 “Ft. AC
1230 I xl
Treaimrnl 2 Anneal: I h aI 900°C ( 16%) “FL FC Solutionanneal: I ‘!‘ahat 1010cC(lS50”F~.0Q Temper: 3 h aI 370°C (700 “F). OQ Treatnwnt 3(b) Anneal: I h at 900 “C ( I650 “F). FC OQ
Treaunrn~ -UC) Anne& I hill 900 ‘C (16.50 “FJ. FC Solution zwnesl: I ‘/> h 8199s “C ( I825 “Fj. F.4C
Temper: 2 h aI 705 “C ( I300 “F). AC ta~Eacht~atment comprised threeprocesses~
?oom Temperature Jlts obtained
Ultimate tensile strength ksi MPa
Heat treatment(a)
Solution mneal: I ‘/J h 31 IOIO”C( 180°F). Temper: 2 hat 610°C I llS0”F~ AC
on Typic
data indicate
Properties
on four specimens
treated
by each method Reduction
i’ield strength hlPa
ksi
Elongation in SO mm (2 in.), %
in area, 92
1005
1-b
970 Y8S IO_‘0
IJI I43 I48
9.0 12.5 7.0 8.0
IIIS I 130
I62 16-l IS5 IS2
65 55 9.0 I’.0
9.5 16.0 23.0 -12.0
I.55 16s YC
13.0
127.5 1315
178 I81 I85 191
1260 1296 1340
183 I88 19-l
1380
200
795 810 830 860
11s II7 I’0 175
70 91 98 85
12.5
60.0 37.0 23.0 32.0
685 710 710
9’) 103 I03
76 79 79
21.0 20.5 I85
6S.0 56.0 61.5
7’0
10-a
80
20.5
60.0
listed: 4C.aircool:OQ.oilquench:
FC. iumscecool:
FAC. forced-tircool
Ibr AAlS S3il -B (5) hlL-S-16993
28.0 14.0 12.5
794 / Heat Treaters
Guide
CA-40 Chemical
COInpOSitiOn. AC1 CA-40: Ni. I I.5 to 14.0 Cr. 0.5 MO (not intentionally
Similar
Steels (U.S. and/or
type 410 stainless; ASTM
Characteristics.
Recommended
0.40 C. I.00 Mn. I SO Si. I .O added)
Foreign).
UNS
J9 I 153;
wrought
A743
Martensite
is most common end-use microstructure
Heat Treating
Practice
Annealing. For maximum softness. parts are annealed at 845 to 900 “C (IS55 to I650 “F). then slow furnace cooled from temperature. The typical ultimate tensile strength obtained is approximately 620 MPa (90 ksi)
Austenitizing and tempering. Following austenitizing, parts are quenched in oil or air. Tempering at 370 to 595 “C (700 to I I05 “F’) is not recommended because in this range impact ductility is low. ln austeni tizing at 980 to IO IO “C ( I795 to I850 “F) and tempering at 3 IS “C max (600 “F max). a typical ultimate tensile strength of approximately I5 I5 MPa (220 ksi) is obtained. At the same austenitizing temperature. typical ultimate tensile strength drops as tempering temperature is increased. At the 595 “C (I IO5 “F) level, the result is 1035 MPa (150 ksi); at the 650 “C (I 200 “F) level. the result is 965 MPa ( 140 ksi); at the 760 “C (I400 “F) level. the result is 760 hlPa (I IO ksi)
794 / Heat Treaters
Guide
CB-30 Chemical
Composition.
AC1CA-15 0.30C. I .OOMn.
I SO Si. 2.0
Ni. 18.0 to 21.0 Cr
Similar
Steels (U.S. and/or
type 312: ASTM
Characteristics. structure contains
Foreign).
UNS
J9 1803; type
33 I.
A733 A chromium grade. The most commonly ferrite and carbides
used micro-
Annealing.
The minimum “C ( 1455 “F). The quenching OF). then air cooling. The approximately 660 MPa (95
annealing temperature for full softness is 790 procedure is furnace cooling to 540 “C (1000 typical ultimate tensile strength obtained is ksi)
794 / Heat Treaters Guide
cc-50 Chemical
COIIIpOSitiOn. Ni. 36.0 to 30.0 Cr
AC1 CC-50:
0.30 C, I.00 hln. I SO Si. A.0
Similar Steels (U.S. and/or Foreign). ASTM
UNS
592615:
type
446:
A7-13
Characteristics. structure contains
A chromium grade. The most commonly ferrite and carbides
used micro-
Recommended Heat Treating Practice Annealing. The minimum annealing temperature
for full softness is790 “C (I455 “F). Parts are quenched in air. The typical ultimate tensile strength obtained is approximately 670 MPa (97 ksi)
794 / Heat Treaters
Guide
CE-30 Chemical
Composition.
AC1 CE-30: 0.30 C. I.50 Mn. 2.00 Si. 8.0
to I I .O Ni, 26.0 to 30.0 Cr
Similar ASTM
Steels (U.S. and/or Foreign).
UNS
J93423:
type
3 12;
743
Characteristics. most commonly
A chromium-nickel used microstructure
grade. Ferrite
in austenite
is the
Recommended
Heat Treating
Practice
Annealing. For maximum corrosion resistance, the minimum annealing temperature is 1095 “C (2005 ‘F). Quenching is in water, oil, or air. The typical ultimate tensile strength ohtained is approximately 670 MPa (97 ksi)
Cast Stainless
Steels / 795
CF-3 Chemical to l?.ONi.
Composition.
AC1 CF-3: 0.03 C. I SO hln. 2.00 Si. 8.0
17.0to21.0Cr
most commonly
Note: CF-3A. CF-3MA. and CF-8A have the same composition ranges as CF-3. CF-3M. and CF-8 respectively. but have balanced compositions so that ferrite contents are at levels that permit higher mechanical property specifications than those for related grades. They are covered by AsThl .
A751 .II.
Similar ASTM
Steels (U.S. and/or Foreign). A35 I, A713, A7-U
Characteristics.
1lNS J92700; type 304L;
A chromium-nickel used microstructure
Recommended Annealing.
Heat Treating
grade. Ferrite in austenite
is the
Practice
The minimum annealing temperature for maximum corrosion resistance is IO-10 “C (I905 “FL Quenching is in water. oil, or air. The typical ultimate tensile strength obtained is approximately 530 MPa (77 ksi)
Cast Stainless
Steels / 795
CF-8C Chemical
Composition.
AC1 CF-SC: 0.08 C. I.50 Mn. 2.00 Si. 9.0
to 12.0 Ni. IS.0 to 2 I .O Cr. Nh Note: Nb. 8 X ?/oC min (I .O 91 max); or Nb + Ta X ?K (I. I “6 max)
Similar ASTM
Steels (U.S. and/or Foreign).
UNS
592600:
type
30-i:
A35 I, A743. A744
Characteristics. most commonly
A chromium-nickel used microstructure
grade. Ferrite in austenite
is the
Recommended Annealing.
Heat Treating Practice
The minimum annealing temperature for maximum corrosion resistance is 1040 “C (I905 “F). Quenching is in water, oil. or air. The typtcal ultimate tensile strength ohtained is approximately 530 MPa (77 ksi). CF-SC may be reheated to 870 to 925 “C (1600 to 1695 “F). then air-cooled to precipitate niobium carbides
Cast Stainless
Steels / 795
CF-8M Chemical
Composition. AC1 CF-8M: to 12.0 Ni. 18.0 to 21 .O Cr. 2.0 to 3.0 Mo Similar ASTM
Steels (U.S. and/or Foreign).
0.08 C. I.50 hln. 2.00 Si 9.0
Annealing. UNS
~92900:
type
3 16;
A35 I, A743
Characteristics. most commonly
A chromium-nickel used microstructure
Recommended
grade. Ferrite in austenite
is the
Heat
Treatina - - ------a
Practice _ .--_---
The minimum ;annealing temperature for maximum corrosion resistance is IO-IO “C I I905 “F). Quenching is in water. oil, or air. The typical ultimate tensile strength obtained is approximately 550 MPa (80 1-c;,
Cast Stainless
Steels / 795
CF42M Chemical
Composition.
AC1 CF-12M:
0. I? C. 1SO Mn. 2.00 Si.
9.0 to 12.0 Ni, 18.0 to 21.0 Cr. 2.0 to 3.0 MO
Similar
Steels (U.S. and/or Foreign).
Recommended Annealing.
Type 3 I6
Characteristics. A chromium-nickel grade. Ferrite austenite alone is the most commonly used microstructure
in austenite
or
Heat Treating
Practice
The minimum annealinp temperature for maximum corrosion resistance is 1040 “C t 1905 “F). The alloy should be quenched from a temperature above 1095 “C (2005 V). Quenching is in water. oil. or air. The typical ultimate tensile strength obtained is approximately 550 MPa (80 ksi)
Cast Stainless Steels / 795
CF46F Chemical
COmpOSitiOn.
AC1 CF-16F: 0.16 C. I.50 Mn. XKI Si.
9.0 to I?.0 Ni. 18.0 to 21.0 Cr. 1.5 Mo ma.\. 0.25 to 0.35 Se
Similar Steels (U.S. and/or Foreign). ASThl
A713
UNS
~92701:
type
303:
796 / Heat Treaters Guide Characteristics.
4 chromium-nickel manly used microstructure
Recommended Annealing. The
Heat Treating
grade. Austenitc
is the most com-
Practice
minimum annealing temperature for maximum corrosion resistance is IWO “C I 1905 “FL Quenching is in water. oil. or air. The
typical ksi I
ultimate
tensile strength
obtained
is approximately
530 MPa (77
796 / Heat Treaters
Guide
CF-20 Chemical IO Il.ONi.
Similar ASTM
COmpOSitiOn. 18.0to2l.OCr
AC1CF-20: 0.20C. I .SOMn.
Steels (U.S. and/or
2.00 Si. X.0
Recommended Annealing.
Foreign).
UNS JW602: tjpe 302:
A743
Characteristics. A chromium-nickel monly used microstructure
grade. Austenite
is the most com-
Heat Treating
Practice
The minimum annealing temperature for maximum corrosion resistance is IO-10 “C ( 1905 “F). Quenching is in water, oil, or air. The typical ultimate tensile strength obtained is approximately 530 MPa (77 ksi)
796 / Heat Treaters
Guide
CH-20 Chemical
Composition.
AC1 CH-20: 0.20 C. I.50 Mn. 2.00 Si.
12.0 to IS.0 Ni. 32.0 to 26.0 Cr
Similar
Steels (U.S. and/or
Annealing. Foreign).
LINS 593-W;
type
309:
ASTM A35 I, Al-43
Characteristics. monlj
Recommended
A chromium-nickel used microstructure
grade. Austrnite
is the most com-
Heat Treating
Practice
The minimum annealing temperature for maximum corrosion resistance is 1095 “C (2005 “Fb. Quenching is in water, oil, or air. The typical ultimate tsnsilr strength ohtained is approximately 610 MPa (88 ksi)
796 / Heat Treaters
Guide
CK-20 Chemical Composition. AC1 CK-20: 0.20 C. 2.00 hln, 2.00 Si. 19.0IO 22.0 Ni. 23.0 to 27.0 Cr Similar ASThl
Steels (U.S. and/or
Foreign).
UNS
J94202:
tjpe
3 IO:
A743
Characteristics. A chromium-nickel monly used microstructure
grade. Austenite
IS the most com-
Recommended
Heat Treating
Practice
Annealing. The minimum annealing temperature for maximum corrosion resistance is 1095 “C (2005 “F). Quenching is in water. oil. or air. The typical ultimate tensile strength obtained is approximately 525 MPa (76 IrsiJ
796 / Heat Treaters
Guide
CN-7M Chemical
Composition. AC1 CN-7111: 0.07 C. I.50 Mn. I.50 Si. 27.5 to 30.5 Ni. 19.0 to 27.0 Cr. 3.0 to 3.0 MO. 3.0 to 4.0 Cu
Similar
Steels (U.S. and/or Foreign).
UNS
N08007:
ASTM
A35 I. A743. A744
Characteristics.
.L\chromium-nickel monly used microstructure
grade. Austsnite
is the most com-
Recommended
Heat Treating
Practice
Annealing. The minimum annealing temperature for maximum corrosion resistance is I I20 “C. (7050 “FL Quenching is in \cater. oil. or air. The typical ultimate lensile strength obtainsd is approximately 180 MPa (69 ksi)
PH Stainless Cast PH Stainless
Steels
Steels
Cast PH Steels. It is desuahle to subject precipitation-hardenable castings to a high-temperature homogenization treatment to reduce allo) segregation and to obtain more uniform response to subsequent heat treatment. Even investment castings that are cooled slowly from the pouring temperature exhibit more nearly uniform properties when they ha\e been homogenized. Homogenizing treatments for I74 PH (UNS S 17400) and AM-355 (UNS S35500)are given in Hea/ Pearing. Volume 4 of .4Sht Handbook (page 788). 17-4PH Castings. When 174PH (ASTM CB-7Cu-I and CB7Cu-2) is cast in plastic-bonded shell molds, the surface is carburized by decomposition of the binder. The added carbon prevents proper heat-treating. Response is obtained when surface carbon is removed prior to the homogenization treatment. In addition to homogenization. other heat-treating procedures for l74PH castings include solution annealing and precipitation hardening. Details of these procedures are given in an adjoinmg table. The preferred temperature range for precipitation hardening is 180 to 595 “C (900 to II00 “F). The mechanical properties obtained at different aging temperatures are given in AS21 Handbook. Volume 4 ipage 791).
The tendency of 17-4PH castings to overage IS reduced by the addition of approximate11 0.255, combined niobium plus tantalum to the alloy. The eff‘ects of time at aging temperature on the mechanical properties of niobium-free and niobium-containing I7-4PH investment castings are given in XM Handbook, Volume 3 (page 79 I). AM-350 and AM-355. Although investment castings made of these alloys do not necessarily require a homogenizing treatment. this treatment provides a more uniform response to subsequent heat treatment. Shell mold and sand castings made of AhIthat were extremely brittle without homogenization regained ductility after homogenizing at 1095 “C (2000 “F) for 2 h minimum. Heat-treating procedures and effects of tempering temperatures up to 650 “C ( I200 “F) on mechanical properties of AM355 shell mold castings are given m .-l.SM Handbook, Volume 1 (page 792). When Ahl-355 castings are welded, maxunum mechanical properties are obtained when the castings are fully heat treated after welding (see adjoining table). Heat treatments prior to welding have little effect on properties when a complete heat treatment follows welding.
1714PH Chemical
Composition.
AISILJNS
(S17400): 0.07 C. 1.00 Mn.
l.OOSi, 3.010 5.0 Ni, IS.50 to 17.SOCr.0.04 to 0.45 Nb
P. 0.03 S. 3.0to5.0Cu.0.15
Similar Steels (U.S. and/or Foreign). S3SS.S604.S622.S643,S82S; A70S; MIL SPEC MIL-C-XI
AMS 53-12, 5343. S3.U. ASME SAS64, SA70S; ASTM AS6-1. A693. I I, MIL-S-81506. ML-S-81591; SAE J-167
Martensitic type 174PH combines high strength and hardness with excellent corrosion resistance. Can be hardened by a single lam-temperature heat ueatment that virtually eliminates scaling and distortion. Similar Lo 15SPH. except has slightly higher chromnml content. Applications include gears. springs. curlerq. fasteners. aircraft parts. turbine parts Forge withm range of IO-IO to I I SO “C ( I905 to 2 IO0 “F)
Recommended
Heat Treating
Practice
For [his grade and for most other precipitation-hardening grades. the final properties can differ somew hat with variations in aping temperature. However. the following procedure is most commonly used: l l l l
Fiial beat treat condition(a) H9CUl
Characteristics.
Forging.
17-4PH: Heat Treating Procedures (Aerospace Practice)
Solution treat by heating at 1025 to I050 “C (I 875 to 1920 “F) Oil quench to room temperature Age at 480 “C (89s “F) for I h and air cool (known as condition H900) Following this heat treatment. a hardness ofapproximately 42 to 44 HRC can be expected
H H H H H H H H H
925 950 IOW 1025 1050 1075 II00 II50 I ISOhllh,
Solution heat treating. set temperature. “C (“F)(b) 104011900)
Solution heat treating, cooling(c)
Aging set temperature, “C (“F)(e)
air. 011. polymer LObelow 180 (900) 30 ‘T 190 “F) \s~ttun I hl,d) 49s (925) SlO(9SO) 510~1ooo) 550( 1025) 565 ( 1050) 580(1075, 595 ( 1100) 62O(llSO) (h)
Aging time, hour@,f,g) I (g.i) 4g.i) -I 4 J 4 4 -l -I lh)
I a) See table forspecitied mmimum tensile strength conversions to heat treat condition 1b1 See table for soak times. 15) 4ir means a1roratmosphere. (d) Artiticial means may he used 10 cool belo\\ ambient Iemperarure u hen necessary to gel below 30 “C (90 “F) orbelo\r lS”C160~‘F~.~e~~me.+l0.i)~ninfor30minages:+lS.-0minforIhagrs; t30 min. 4 nlin for I .S h ages: and +-lS. Xl for 3.1. and I6 h ages. (f) To gel a lower hardness for preresrcd material. a set temperalure of 5 “C ( IO “F) higher than specified ma) he used cgr An addilional I IO I .S h af the spcsitied temperature oran additional 5 to IO “C I IO to 20 “FI for an additional I IO I .S h after agmg may be used IO loner hardness or other engineering propenics. I h) H I I SOhl is ao imermediate soft condition lhar must be re-solution heat lrcarcd IO obtain a different final condition. To get H I ISOM. solution heal meat. then heat at 76O”Cl I-KK”F~airsool to 30”C(9O”Rfor? to2.S h plus62O’C I 1150°F) ior-l h. ,i) l74PH and IS-SPH castings. H 9OOand H 925 time shall lx I.5 h Source: AMS 27591.1
798 / Heat Treaters Guide 17-4PH: Soak Times for Solution Heat Treating (Aerospace Practice) Product
form
Minimum soak time, solution heat treating, min(a,b)
17-4PH: Required Hardness After Aging (Aerospace Practice) Product
form
All Sheet All except sneet
3plus I minpereach0.25mm(O.OIOin.) 30per25mm(I in.)
(a)l’ime.+lO.-Omin.(b) Inallcasespartsare heldforsuff~cienttimetoensurethatthc center of the most massive sectton has reached temperature and the necessary uansformation and diffusion have taken place. Source: AMS 27.59/3
Condition H900 H 925 H 950 HI000 H 1025 H IOSO H 1075 H 1100 H IISO H I ISOM
Elardneas,
EIRC
401047 38 to 45 371044 36 to 43 34 to 42 32 to 38 31 to38 30 to 37 28 to 37 24 to 30
Source: AMS 275913
174PH: Microstructures. (a) Electrolytic: HNO,-acetic, then 10% oxalic. 1000x. Solution treated by holding at 1040 “C (1905 “F), 30 min. Air cooled (condition A). Structure: ferrite stringers in martensite matrix. (b) Electrolytic: HNO,-acetic, then 10% oxalic. 1000x. Solution treated, as (a). Aged 1 h at 480 “C (895 “F). Air cooled (condition H900). Structure: ferrite stringers in martensite matrix. (c) Electrolytic: HNO,-acetic, then 10% oxalic. 1000x. Solution treated, as (a). Aged 4 h at 550 “C (1020 “F). Air cooled (condition H1025). Structure: small ferrite stringers in martensite matrix. (d) Vilella’s reagent, 50x. Bar, solution treated at 1025 to 1050 “C (1875 to 1920 “F): Air cooled. Aged at 575 to 585 “C (1065 to 1085 “F). Air cooled (condition H1075). Banding resulting from alloy segregation appears as dark streaks in a martensite matrix. (e) Vilella’s reagent, 200x. Same as (d), except structure shows the banding blending with matrix. (f) Marble’s reagent, 75x. Spot welded sheet. Shows void-type defect (black) in the weld zone. Defect the result of microcracking
Cast PH Stainless Steels / 799 17-4 PH: Tensile Strength Conversions (Aerospace Practice) Product
form
Bar. forging. Sheet. strip. casting Bar. forging, Sheet. strip. casting Wmught casting Bar, forging, Sheel strip, Bar. forging. Sheet. strip, Bar. forging, Sheet. strip, Casting Bar, forging, Sheet. strip,
tubing. billet plate tubing, billet plate
tubing. billet plate Nbing. billet plate tubing, billet plate tubing, billet plate
Source: AMS 275913
Tensile strength minimum, MPa (ksi) 1310(190~ 1310~190) 1140(180) lLlO(l80) ll75(170) 1175(170) ll10(165) 103.5~150) 1070(Iss) lo7o(lss, 1000(11.5~ 1000~14SJ %5(140) %5 ( I-10) 895 I 130) 930(135) 930( 135)
to Condition
Condition H9OO H9OU H9tXl H 925 H 925 H 925 H 950 HIOOO H 1025 H 1025 H 1075 H 1075 H II00 H II00 H II00 H II.50 H II50
Cast PH Stainless Steels / 799
1717PH Chemical Composition.
AlSI/UNS (S17700):O.O!JC. 1.00 Mn,
0.040 P.O.04OS. l.OOSi.6.50to7.75
Ni. 16.OOto 18.00Cr.0.75
to 1.5OAl
Similar Steels (U.S. and/or Foreign). AMS 5528. 5529. 5568, 5644.5673.5678.5824; ASME SA705: ASTM A3 13. A5 IO, A56-l. A579. A693, A705; MtL SPEC MIL-S-25a3. MlL-W--16078; SAE J-t67; (Get) DIN 1.4568
17-7PH: Required Hardness After Aging (Aerospace Practice) Product form All
Characteristics.
Semiaustenitic type I7-7PH combines high strength and hardness with excellent corrosion resistance. Spring wire can be produced by severe cold drawing, followed by hardening with a single lowtemperature heat treatment. Applications include springs. knives. and pressure vessels
Forging.
Forge within
Recommended
range of 1040 to I I50 “C ( 1905 to 2 100 “F)
Heat Treating
There can be variations in the treatment different heat treating procedures are:
Practice for this type. Details of two
Condition RH 950 RH loo0 RH 1050 RH IO75 RH I100 In 9.50 I-H IO(w) I-H IOSO TH 1075 TH II00 CH900
Aardness, ARC 42 to 49 411046
401045 38 IO 43 34to-lO 42 to 18 40 to 16 38to4-1 37 IO 42 33 1039 46min
Source: XklS 275913
Heat Treatment No. 1 l l l l
Mill anneal at 1065 “C (I950 “F). Fabricate Heat to 790 “C (I455 “F) for I .5 h Cool to room temperature within I h and hold for 0.5 h (condition T) Heat to 565 “C (1050 “F) for I.5 h and air cool (condition THl050). Hardness, 43 HRC
Heat Treatment No. 2 l l l l
Mill anneal at 1065 “C (1950 “F). Fabricate Heat to 955 “C ( 1750 “F) for IO min Cool to -74 “C (-100 “F) and hold for 8 h (condition R 100) Heat to 510 “C (950 OF) for I h and air cool (condition Hardness. 47 HRC
RH950).
17-7PH: Tensile Strength Conversions (Aerospace Practice)
to Condition
Product form
Tensile strength minimum, MPa (ksi)
Condition
Sheet. strip Plate Bar Sheer. strip. plate BZU Wrought Sheet. ship. plate, \\eldrd tubing Blu Sheet. strip
1.wl(210) 1380(200) 127S(l85) 12JOtl80) 1175~170) 1035(150) 12~0(180) 1180~170) (varies with Thickness)
RH950 RH950 RH 950 RH I050 RH IO.50 RHIIOO I-H 1050 TH 1050 CH 900
Source: AhlS 275913
800 / Heat Treaters Guide 17-7PH:
Heat Treating Procedures (Aerospace Practice)
Fiial heat treat condition(a)
RH950 RH loo(J RH I050 RH 1075 RH II00 TH 950 TH 1000 TH IO.50 TH 1075 TH II00
Solution heat treating, set temperatures, “C (OF)(b)
Solution heat treating, cooling(c)
1050r1925, 1050~19’51 lOSOtl925~ lO50( 1925) 1050119,5~ 1OSOt1975, IOWt 1925, 1050119~.51 I0501 IPi, lO50( IY25)
Air Au Air Air Air Air Air Air r\ir Au
Austenite conditioning and transformation, ‘C (°FN4c)
9% I 1750).(b), air LXXIIto anlhientrind\\ ithm I h cool to twlou -70 t-90). so& 8 IO9 h. 3nd3ir u 3rmto smhientresul&in condition R 7601IU)OIfor’H)mlntohzlllu IS Ih(JlFornot le>j th3n30 min-rrwlh insonditionT
Aging set temperature, ‘C (“F)(d)
SlO~9Sll, 54of loool 56s I 1050) 5801I0751 595 1I IOO, slo(9sOt 540~IOOO) 565 I I ON) 580( 1075) S9SfllOO)
Ash time, hour(d.e,f)
1 1 I I.S I.5 I.S I .5 I .s
tu) Seetable for specified minimum tensile >tren@hcomersions IObenttre3tconditmn (b I Seetable tor so3hrime\ (cl
17-7PH: Soak Times for Solution Treating and Austenite Conditioning (Aerospace Practice)
Product form
Sheet All exceptsheet
Minimum soali time. solution heat treating, min(a.b)
3 plus I mm French 0.25 mm tO.OlOin ) 30 per 25 mm ( I in.)
hiinimum soak time austeniteconditioning, min(a,b)
IO plus I min per each25 mm tO.010in.) 30perZjmmtI 1n.L
ta)T~mr.+lO. ~)min.tb)Inalls3ses.p3rts~rheld forsufticicnttinw toensur?that the centcrof the mostmtisive sectionha reachedtemperatureand the necessw transformationanddiffusion hale t&en place Source:.\hlS 2759/J
17-7PH: Microstructures. (a) Fry’s reagent, 100x. Forging in as-forged condition. Structure: islands of ferrite in austenite matrix. Concentrations of carbide particles adjacent to ferrite islands. (b) Fry’s reagent, 100x. Same as (a). Solution treated 1 h at 1040 “C (1905 “F). Air cooled. Ferrite islands (light etching) are smaller and more dispersed than (a), possibly because of more carbide in solution in the austenite. (c) Fry’s reagent, 100x. Same as (b), except reheated at 955 “C (1750 “F). Air cooled to -74 “C (-100 “F). Aged at 510 “C (950 “F). Aircooled to room temperature. Structure: islands of ferrite (darker etching) in martensite matrix
(continued)
Cast PI-I Stainless Steels / 801
17-7PH: Microstructures (continued). (d) Electrolytic: HNO,-acetic, then 10% oxalic. 1000x. Mill annealed (solution treated, condition A) at 1065 “C (1950 “F). Structure: ferrite stringers in austenite matrix. ASTM grain size, No. 12. (e) Electrolytic: 10% sodium cyanide. 500x. Solution treated at 1065 “C (1950 “F). Etched to emphasize ferrite form. Structure: ferrite stringers and globules in austenite matrix. (f) Vilella’s reagent, 1000x. Same as (e), except reheated and held 10 min at 955 “C (1750 “F). Air cooled. Held 8 h at -74 “C (-100 “F). Held 1 h at 510 “C (950 “F). Air cooled (condition RH950). Ferrite stringers in martensite matrix. (g) Vilella’s reagent, 1000x. Same as (e), except reheated and held 1.5 h at 760 “C (1400 “F). Air cooled to 15 “C (60 “F). Held 0.5 h. At 565 “C (1050 “F), 1.5 h. Air cooled (condition TH1050). Same structure as (f). More ductile. (h) Electrolytic: HNO,-acetic, then 10% oxalic. 1000x. Cold rolled at the mill. Held 1 h at 480 “C (895 “F). Air cooled (condition CH900). An essentially martensitic structure. Austenite was transformed by cold rolling. (j) As polished, not etched. 500x. Section through an area of failure (black void) in an annealed part. Failure caused by severe embrittlement due to nitriding during annealing. Dark particles along void are nitrides
Cast PI-I Stainless Steels / 801
PH 157Mo Chemical Composition. AIWJNS (~15700): 0.09 C, 1.00 hln. 0.040 P.6.50 to 7.75 Ni. 0.030 S. I .OO Si. l-1.00 to 16.00 Cr. 2.0 to 3.0 MO. 0.75 to I.50 Al Characteristics. A Type 632. Forging. Forge within range of Recommended
nonstandard
IWO to I IS0 ‘C ( 1905 to 2 100 “F)
Heat Treating
Practice
There can he variations in the treatment different heat treating procedures are:
Heat Treatment No. 1 l
grade
Mill anneal at 1065 “C (I990 “FL Fabricate
for this type. Details of tmo
l l l
Heat to 790 “C t 1155 “F) for I.S h Cool to room temperature \\ ithin I h and hold for 0.5 h (condition T) Hsat to 565 “C ( IOSO “Fb for I .S h and air cool (condition THIOSO). Hardness. 4-l HRC
Heat Treatment No. 2 l l l l
hlill anneal at 1065 “C ( 1950 “FL Fabricatr Heat to 955 “C ( I750 ‘F) for IO min Cool to -71 iC (-100 “F) and hold for 8 h (condition RIO) Hsat to 510 “C (MO “F) for I h and air cool (condition Hardness. 48 HRC
RH950).
802 / Heat Treaters Guide PH15-7Mo: Practice) Product
Required Hardness After Aging (Aerospace
form
Condition RH950 RH 1000 RH 180 RH 1075 RHllOO TH IO.50 TH 1075 I-H 1100 CH900
Sheet
Rardness,
PH15-7Mo: Tensile Strength Conversions (Aerospace Practice)
ARC Product
form
Sheet. Bar Sheet. Sheet. Sheer. BX Sheet.
strip. plate
Tensile strength minimum, MPa (ksi)
to Condition
Condition
46[050 -12t0-16
39 10 45 381044
34 to 42 401046
39to-U 3htoII 46Ilutl
strip. plate strip, plate strip. plate strip
lSSS(225J 1300(200) 1310(190) 14lst205J 1310~190~ 117.5(170) I655 (240)
RH 950 RH 9.50 RH 1050 THlcml I-H I050 TH 1050 CH9tXl
Aging set temperature. “C (“F)(d)
A&g time, hour (d,e,f)
Source: AhlS 275913 Source: AMS 275913
PH15-7Mo:
Fiial heat treat condition(a) RH950 RH 1000 RH IOSO RH 1075 RH II00 TH950 TH 1000 7-H 1050 TH 1075 TH II00
Heat Treating Procedures (Aerospace Practice) Solution heat treating, set temperatures, “C (“F)(b)
rosoil925; 1050( 1925) 1050~1925) lOSO( 1925) lOSO( 1915) lOSO( 1925) lOSO( 192st 1050~1925~
Austenite conditioning and transformation, “C (“F)(b.c)
Solution heat treating, cooling(c) Air AU Air Air Air Air Air Air Air Air
95.5 (1750). (h).ircool foambient and N ithin I h cool to helow -70 (-90j,soclkXto9h.andrur\~arm to ambient-results tn condition R 76Ot 1100) for90mm to below Is (60) for not less than 30minresults inconditionT
SlO~9.50~ 510 i 1000) 565 ( 1050) 580 llO7S) 59st1100, 510 (9.50) s-lo I IOGO~ 56.5 ( 1050) 580 t 1075) s9stllOO~
I I I I I I. I. I. I. I.
to) See table for specified minimum tensile strength conversions to heat treat condition. (h) See tahle for soak times.(c) Air means air oratmosphere. (d) An additional I to I .5 hat the specified temperatureoranadditional6 to IO “C( IO to 20°F) foran additional I to I..( h after aging ma) be used to lower hardness orotherengineering properties. (ejlime. +lO. amin for 3Oninages; +lS. 4min for I h ages: t30.4min for I.S hagcs;and t-U. 4)mtn for 3.4. and I6 hages. tf)Toget a lower hardness forpretested material.aset temperahwe of 6 “C ( IO “R higher than specified ma! he used Source. AhlS 275913
PH15-7Mo: Soak Times for Solution Treating and Austenite Conditioning (Aerospace Practice)
Product
form
Sheet All except sheet
Minimum soak time. solution beat treating, min(a,b) 3 plus I mm per each 0.25 mm (0.010 in ) 30perEimmtI in.1
Minimum soak time, austenite conditioning, min(a,b) lOplus I nlin perrach (0.010 in.) 30per25mmiI in)
25 mm
~a)Time.+lO.-Omin.(h)lnallcases.psrtsare held forsufticienl ttme toensurethat the center of the most massive section has reached temperature and the necessaq transformation anddiffusion habe taken place. Source: AhlS 2759/3
802 / Heat Treaters Guide
AM-350 Chemical Composition.
AWUNS (S35000): 0.07 to 0. I I C. 0.5 to I .?S hqn. 0.040 P. 0.030 S, 0.50 Si. 4.00 to 5.00 Ni. 16.00 to 17.00 Cr. 2.5 to 3.25 hlo. 0.07 to 0. I? N
Characteristics. Forging.
A Type 633. nonstandard
Forge within
grade
range of 1040 to I IS0 ‘C t 1905 to 2 100 “F)
Recommended
Heat Treating
Practice
hlasimum mechanical properties may be obtained for this grade by either of the folloir ing procedures. The choice between the two procedures often depends upon whether or not the subzero cooling facilities are a\ ;tilablr
Cast PH Stainless Steels / 803 Heat Treatment No. 1 (subzero cooled and tempered) l
Heat to 925 to 955 “C (I695
l
Coolto-74”C(-lOO”F)for3h
l
Heat to 4SS to 540 “C (850
AM-350:
to 1750 “F) to 1000 “F) for 3 h. Hardness.
45 HRC
Heat Treatment No. 2 (double aged) l
Heat
l
Cool to room temperature Heat to 455 to S-10 “C (850
l
to 715 “C (I 370 OF) for 3 h to 1000 “F) for 3 h. Hardness,
41.5
HRC
Heat Treating Procedures (Aerospace Practice)
Fiial
IEat treatcondition(a) SC-T 850 scT9so SCTIOOO scTll00
Solution heat treating, set temperatures, “C (“F)(b)
Solution heat treating, cooling(c)
Ioso(l92s) lOSO(l925) lO50( 1925) Ioso(l92s)
Air Air Air Air
Austenite conditioning and transformation, ‘?I’ (OF)(b,c) 355 ( 1750). (b), air cool belo\\ 70 ( -90). soak for 3 10 5 h. and air warm to ambient
Aging set temperature, “C (“F)(d)
Mw time, hour (d.e,f)
4.55 (850) SlO(9SO) 530 ( 1000) 595 (I 100)
3 3 3 3
(a) See table for specified minimum tensile strength conversions to heat treat condition. (h) See table for soak times. tc) Air means air or atmosphere. (d) lime, + IO. Xl min for 30 min ages: + IS. -0min for I h ages; +30.4 min for I .S h ages; and +45. Xl for 3.4. and I6 h ages. te) To get a lower hardness for prelested marerial. a set temperature of 5 “C ( IO “F) higher than specified may be used. (0 An additional I to I .S h after aging may be used to lower hardness or other engineering properties. Source: AMS 2759/3
AM-350: Soak Times for Solution Treating and Austenite Conditioning (Aerospace Practice)
Product
Minimum soak time, solution beat treating, min(a,b)
form
Sheet All excepr sheet
3 plus I mm per each 0.25 nun (O.OlOin.) 30per25mm(I in.)
Minimum soak time, austenite conditioning, min(a,b)
AM-350: Practice) Product
Required Hardness After Aging (Aerospace
form
All
IO plus I min per each 25 mm (O.OlOin.) ISper2Smm(l in.) Source: A hlS 275913
(a)Time.+lO.-Omin.(b)lnallcases.partsare hrldforsufflcient time toensurethalrhc center of the most masske section has reached temperature and the necessary transformation and diffusion have taken place. Source: AMS 2759/3
AM-350: Tensile Strength Conversions (Aerospace Practice) form
Tensile strength, minimum MPa (ksi)
Sheet. strip, plate. tubing Sheet. ship. plate. tubing Bar. forgings, tubing
l280( 185) 1175(170) ll4Otl65)
Product
Source: A MS 275913
to Condition
Condition SC-I- 850 scT950 SCT loo0
Condition SCT 850 SCT950 SCT 1000 SCTIIOO
Eardness, 41 38 36 35
ERC
1048 fo 45 to 43 to 12
804 / Heat Treaters
Guide
AM-350: Microstructures.
(a) Electrolytic: 1096 ammonium persulfate. 1000x. Strip, solution treated at 1065 “C (1950 “F). Cooled in air. Structure: ferrite pools in austenite matrix. Carbides in solution. Normally, ferrite content is from 10 to 15%. (b) Electrolytic: 10% ammonium persulfate. 1000x. Strip, solution treated at 930 “C (1705 “F), 15 min. Cooled at -74 “C (-100 “F), 3 h. Ferrite islands with precipitated carbides at boundaries. Martensite matrix and retained austenite. (c) Electrolytic: 10% ammonium persulfate. 5000x. Same as (b). except a transmission electron micrograph of a surface replica. Shows carbides precipitated at boundary of a ferrite island. Acicular martensite and retained austenite matrix (smooth areas). (d) Super picral. 100x. Forging, solution treated and aged. Structure: banded ferrite (4% by area, light constituent). Martensite matrix. Same structure as (e), except different etchant and magnification. (e) Vilella’s reagent, 500x. Forging in solution treated and aged condition. Structure same as (d), banded ferrite in martensite matrix. Appears different because of different etchant and higher magnification. (f) Electrolytic: 10% oxalic acid. 1000x. Solution treated at brazing temperature. Conditioned 5 to 10 min at 930 “C (1705 “F). Cooled below -87 “C (-125 “F). Aged at 455 “C (850 “F), 3 h. Condition SCT850. Delta ferrite and precipitated carbide in martensite matrix
804 / Heat Treaters
Guide
155PH Chemical COIIIpOSitiOn. AISI/UNS (S15500): 0.07 C. I .OO hln. 0.0-10 F! 0.030 S, 1.00 Si. 350 to 5.50 Ni. 14.50 to 15.50 Cr. 2.5 to 1.5 Cu. 0. I5 to 0.45 Nb
Characteristics.
A Type 631. martensitic (maraging) stainless steel. Has high strength. hardness. and corrosion resistance. Applications include pears. cams. cutleq. shafting. and aircraft parts
Cast PH Stainless 15-5PH: Tensile Strength (Aerospace Practice)
Conversions
to Condition
Fiial
Tensile strength Pmduct form Bar. forging. Sheet. snip. Casting Bar. forging, Sheet. snip, CZtiIlg Wrought CaStiIlg Bar. forging, Sheet. snip, Bar. forging. Sheet. strip, Bar. forging, Sheet strip, Casting Bar. forging. Sheet. strip.
minimum,
tubing, billrt plate tubing. billel plate
Nbing. bilk1 plak Nbing, biller plate Nbinp, biller plak Nbing. billet plate
hWa (ksi)
1310l190) 1310(190, I240 (180) 1210(180) 1175 (170) 1175 (170) 1110~16S) 1035 (150) 107O(ljS) 1070 (155) 1000~145~ 1000~11.5, 965 (110) 965 (I401 89.5 I 130) 930 (13s) 930(1X)
Condition H900 H900 H9OO H 925 H 91S H 925 H 950 HI000 H 1025 H 1025 H 1075 H 107.5 H II00 H II00 H II00 H II50 H II50
Source: AhlS 275913
15-5PH: Practice)
Required
Pn3duct form All
Source: AhlS 2X9/3
Hardness
After Aging (Aerospace
Condition H900 H 925 H 950 H IO00 H 102.5 H IOSO H 1075 H II00 H II50 H I ISOh
15-5PH: Practice)
Hardness.
HRC
40 to 47 38 ro45 37to-U 36 to 43 34 10 42 32 to 38 311038 30 to 37 28 to 37 ‘110 30
heat treat condition(a)
Heat Treating Solution heat treating, set temperature, “C (“F)(b) IO-IO ( 1900)
H H H H H H H H H
925 950 loo0 IO’S IO50 1075 1100 IISO I I 50hlI h)
Procedures
Solution heat treating, cooling(c)
Steels / 805
(Aerospace
Aging set temperature, “C (“F)(e)
Aghs time, MW
air. oil, polymer 10 480 (900) below 30 “C (90 OF) within I h(d) 49s (92s) SlO(95Oj 510 (IWO, 550 I 10~5) 565 (10.50) S80 (107S) 595~1100) 6’O~llSO) (h)
I 1g.i)
4g.i) 4 1 -l -I -I 4 1 00
(a) See table for specified nunimum tensile wength somersions IO heat treat condition (b) See table for soak times. (5) r\ir means air or a!mo\phere. (d) Artiticial means ma) be used to cool below ambient kmperarure when necessaq to get belou 30 “C (90 ‘F) orbelo\s l5”C~6O”F1.~e~Time.+l0.~:)n~infor30minnges:+lS.~)mjnforI hages: +30.-OminforI Shage~:~d+1S.~for3.1.~dl6hages.(f)Toge~alolcerh~dness for pretested material. a se1 temperarure of 5 “C ( IO “F) higher than specified may be used. I~I An additional I to I .S h al the specified temperature wanadditional 5 to 10°C I IO to 20 “FI for an additional I to I 4 h after aging ma! be used to loner hardness or other engineenng proprrnes I hr H I I SOhl is an inrermediare soft condition that must be re-solurion heal trealed to obrcun a different final condition. To get H Il5Ohl. solution heat treat. then heat at 760 “C I I400 “FL alrcool to 30 “C (90 “FI for 2 to 2.5 h plus 610 “C ( I I50 “F) for 3 h. (i) I74PH and IS-5 PH castings. H 900 and H 925 time shall be I.5 h. Source: AhlS 2759!3
15-5PH: Soak Times for Solution (Aerospace Practice) Product
form
Sheer GII ewepl sheet
Heat Treating
hlinimum soak time, solution heat treating, min(a,h) 3 plus I ninpereachO.25 30per2Snun(I in.1
mm(O.OlOin.)
ta,Tune. +lO. 4mm. (b) Inallcmo. pansare held forsuftkient time toenwrethat the center of the most massive section h& reached tempenrure and the necessaq uansformalion and diffusion hake taken place Source. AhlS 275913
Cast PH Stainless Steels / 805
A-286 Chemical Composition. AISI: Nominal. 0.08 C max. I .3 hln max. 0.3 Si max. 26.00 Ni max. 15.00 Cr max. 1.3 hlo max. 0.003 B max. 0.3 L max. 3.0 Ti max. 0.35 Al max. IJTVS: 0.08 C max. I.50 hln max. 0.045 P max. 0.030 S max. 1.00 Si max. 21.00 IO 28.00 Ni. 12.00 to IS.00 Cr. 2.50 to 3.50 hlo.0.OOl0to0.OIO B. I.55 toL00Ti. I.50 to 3.00 W.O.35 Al max
h4asimum mechamcal properties may he ohtained for this grade h) either of the follo\\mg procedures. The choice between the two procedures often depends upon whether or not the subzero cooling facilities are available.
Similar Steels (U.S. and/or Foreign).
Heat Treatment No. 1
UNS K66386: Ahls 5525. 5731. 5732. 5734, 5735.5736, S737.5801.58OS; ASME SA638; ASTbl A453. A638: SAE J-167 tA286): (Ger.) DIN 1.1980
Recommended
l l
Characteristics.
~-186 is also kno\\n as an iron-hase heat-resisting alloy. Capable of retaining high strength and good corroston resistance at service temperatures up to 705 “C ( 1300 “FL llsed in aerospace and oil country applications
l
Forge within
range of 10-K) to I I SO “C t 1905 to 2 IO0 “F)
Practice
Heat IO 925 to 955 “C ( 1695 to l7SO “Ft Cool to -7-t “C t -100 “F) for 3 h Heat to -tSS to S-10 “C i8SO to 1000 “Ft for 3 h. Hardness. -IS HRC
Heat Treatment No. 2 l l
Forging.
Heat Treating
l
Heat to 7-tS “C I I370 “F) for 3 h Cool to room temperature Heat to 155 to S-10 “C (850 to 1000 “F) for 3 h. Hardness. 41 .S HRC
806 / Heat Treaters Guide In aerospace practice, parts are solution treated in the aged condition. Set temperatures for solution treating and set temperatures and times for aging are given in an adjoining table. Sheet is cooled in air or atmosphere. Bar is oil or polymer quenched. Soak time for all product forms (in min: +lO. -0) is 30 min per 3-S mm (I in.). Parts are held for sufficient time to ensure that the center of the most massive section has reached temperature and the necessary transformation and diffusion have taken place. Required hardnesses after aging for different product forms and conditions are given in an adjoining table. A-286 is procured in two heat treated conditions: ( I) 900 “C ( 1650 “F) for maximum strength and (2) 955 to 980 “C (I750 to I795 “F) for maximum high temperature properties
A-286: Required Hardness After Aging (Aerospace Practice) Product form
Condition MPa (ksi)
Eardness, HRC
Sheet, plate All Sheet. plate Sheet, plate Bar. forgin8s Bar.\cilT
86Ot 125) 89s ( 130) 930(135) 965 (MI) 965(140) I380 t 200)
24 to 35 24 to 36 24 to 31 24 10 38 29 lo 38 40min
Source. AhlS 2799l3
A286:
Solution Heat Treating and Aging Requirements (Aerospace Practice)
PIdUCt
Sheet Bar and Wire(b) Bar and For@ngst bi Bar anal Forgin@ b) Sheet and Plate. Welding Grade(b) Bar and Forgings. Welding Grade(b)
Solution beat treat(a) 980 “C ( 1800 “F)
49CZ treatment 720”C(l3’5”F) -
. 16h . min
980 “C i I800 “FL and cold worked(a) 980”C(l8OO”F) 9OO”c~l65o”F) 980 “C ( I800 “F)
6.50 to 70s “C( 1200 to l3OO”F). 8 h. nin 720”Ct132S°F).16h.min 720 “C ( I325 “R. I6 h. min 720”C(l32S”F) . l6h . min
955 “C ( 1750 “F)
720 “C ( I325 “F). I6 h. min
(a) Do not resolution heat treal cold worked material or parts. (b) Consumable electrode remelted. Source: AhlS 275913
Minimum Tensile strength after aging Varies with thickness from 860 to 965 MPa (125to I4Oksi) 1380MPa(NOksi) 895 MPa(l3Oksi) 965 hTPa( I JO ksi) Varies u ith tickness from 860 (0 %5 MPa (I25 to I-lOhi) 895MPa~l30ksi)
806 / Heat Treaters Guide
AM-355 Chemical Composition.
AISI/UNS (S35500): 0. IO to 0. IS C. 0.5 to I .2S Mn. 0.040 P. 0.030 S, 0.50 Si. 4.00 to 5.00 Ni. 15.00 to 16.00 Cr. 2.5 to 3.25 Mo, 0.07 to 0. I3 N Characteristics. A Type 634. Forging. Forge within range of Recommended
nonstandard
grade
lo-10 to I I50 “C (I905 to 2100 “F)
Heat Treating
AM-355: Soak Times for Solution Treating and Austenite Conditioning (Aerospace Practice)
Practice
Maximum mechanical properties may be obtained for this grade by either of the following procedures. The choice between the two procedures often depends upon whether or not the subzero cooling facilities are available
PnxIuct form Sheet All e~cepc sheet
hlioimum soak time, solution heat treating, min(a,b) 3plus I nlinpereach02Smm (0.0lOin.j 30pr25 mm{ I in.)
Minimum soak time austeoite cooditiouiug, mW&) IOplus I minpereach2Smm (O.OlOin.) lSper2Smm(l in.)
ta)lime. +IO.-Omin. tb) Inallcases. partsare heldforsuflicient time toensurethatthe center of the most massive section has reached temperature and the necessary uansformation and diffusion have taken place. Source: AMS 27W3
Heat Treatment No. 1 (subzero cooled and tempered) l l l
Heat to 925 to 955 “C ( 1695 to I750 “F) Coolto-71°C~-1000F)for3h Heat IO 455 to 540 “C (850 to 1000 “F) for 3 h
AM-355: Tensile Strength Conversions (Aerospace Practice)
Heat Treatment No. 2 (double aged) l l l
Heat to 745 “C ( I370 OF) for 3 h Cool to room temperature Heat to 455 to 540 “C (850 to 1000 “F) for 3 h
Pruduct form Sheer. snip. plate Castings Bar. forgings. Nbing Sheet. strip. plate Source: AhlS 27SW3
Tmsile sh-ength, minimum, hfPa (ksi) 1310~190) I?--IoIIRO) 1175(170) I110(165)
to Condition
Condition SCT SCT SCT SCT
850 8SO I000 1000
Cast PH Stainless Steels / 807 AM-355:
Heat Treating Procedures (Aerospace Practice)
Final heat treat condition(a)
Solution heat treating, set temperatures, “C (W(b) 1040(1900) 1040(1900)
SCT 850 SCT loo0
Solution heat treating.cooling(c) air or water air or wafer
Austenite conditioning and transformation, “C (“F)(b,c) 955 ( 1750). (b). water quench, cool bclou -70 1-90) for 3 to 5 h. and airwarmloamhienl
Aging set temperature, “C (OF)(d)
Aging time. hour(d+,f)
-155 (890) S-lOl looo,
3 3
(a) See table for specified minimum tensile svenglh convrnions IO heat treal condition (hi See table for soak limes (c) Air means air or annospherc. (d) An additional I IO I .S h at thespecified temperature oran additional 6 to 10°C ( 1010 20°F) foran additional I IO I .5 h afwaginp may be used to louerhardnessor otherengineeringpmperties (c)Time. +lO, -0 min for 30min age; + IS. -0 min for I h ages: +30.4l mm for I .S h ages: and +15.4 min for 3.4. and I6 h ages. ( f) To ger a lower hardness for prelesrrd material. a set temperature of 6 “C ( IO “F) higher than specified may be used. Source: AMS 27S9/3
AM-355: Practice)
Required Hardness After Aging (Aerospace
Product form All Plate Bar. forgings
Condition SC-f 850 sc-rlooo SC-T 1000
Hardness. HRC -II to47 37 to 4.3 38lO-U
Source: AMS 275913
AM-355: Microstructures. (a) 5 g (0.2 oz) copper chloride (CuCI,), 100 mL (3.38 fluid oz) hydrochloric acid, 100 mL (3.38 fluid oz) methanol (Kalling’s reagent 2) 400x. Forging, forged at 1150 “C (2100 “F). Cooled to -74 “C (-100 “F). Held 3 h. Reheated to 1040 “C (1905 “F). Held 2 h. Furnace cooled to 1025 “C (1875 “F). Oil quenched. Cooled to -74 “C (-100 “F). Held 16 h. Reheated to 775 “C (1425 “F). Held 2 h. Cooled to -74 “C (-100 “F). Held 5 h. Reheated to 525 “C (975 “F). Held 3 h. Air cooled. Alloy segregation resulted in excessive retention of austenite. Structure: large patches of retained austenite in martensite matrix. (b) Same as (a), except specimen has wholly martensitic structure. (c) Electrolytic: 10% ammonium persulfate. 500x. Bar, annealed at 760 “C (1400 “F), 3 h. Water quenched. Aged at 595 “C (1105 “F), 3 h. Carbide precipitated at grain boundaries and throughout martensite matrix. Stringers are delta ferrite with finely precipitated austenite. (d) Electrolytic: 10% ammonium persulfate. 500x. Bar, annealed 5 min at 1040 “C (1905 “F). Cooled at -74 “C (-100 “F), 3 h. Heated at 955 “C (1750 “F), 1 h. Cooled at -74 “C (-100 “F), 3 h. Tempered at 540 “C (1000 “F), 3 h. Air cooled. Dispersed carbide and some ferrite stringers in martensite matrix. (e) Kalling’s reagent, 50x. Forging. solution treated and aged. Large white patch is retained austenite caused by alloy segregation. Tempered martensite matrix. Black squares are microhardness indentations
808 / Heat Treaters
Custom
Guide
450 (XM-25)
Chemical
Recommended
Characteristics.
ln aerospace practice. minimum soak time For Custom 450 is 30 min per 25 mm (1 in. 1. In all cases, p&arts ;LTe held for sufficient time to ensure that the center of the most massive sectton has reached temperature and necessary transformation and diffwon have taken place
COIIIpOSitiOn. AISI/UNS (S45000): 0.05 C. 1.00 Mn. 1.00 Si. 11.00 to 16.00 Cr. 5.00 to 7.00 Ni. 0.030 I? 0.030 S. I.25 to 1.75 Cu. 0.5 to I .O hlo. 8 s CC min Nh A nonstandard
stainless steel
Custom 450: Required (Aerospace Practice)
Hardness
Producl
Condition
After Aging
Custom 450: Heat Treating Practice)
Hardness, form
All
HRC,
39 37 36 34 JO 26
H IOQO H 1050
H 1100 H I I50 Sourer: ALlS 275913
Producl
form
W’roughr Wrought Hrought Wrought H rought Source. AhlS 27591.1
Tensile strength. minimum, hlPa (ksi) 1210~180~
I I75 I 170, 1035 I I501 looO~l-l5~
89.5 I 130,
Solution
minimum
HWU H 950
Custom 450: Tensile Strength Conversions Condition (Aerospace Practice)
Heat Treating
to
Condition H900 H 950 H IO25 H 1050 H 1100
H 900 H H H H H
950 IO00 1025 1050 I IO0
Procedures
(Aerospace
heat
treating. set Final heat treat condition(a)
Practice
temperature, “C VW
Solution heat treating, cooling
IO-IO I I900 I .Air. atmosphere. oil. polymer. \\ater
Agiug set temperature, “C mm)
Aging time,
-I80 (Yoo)
4
5lO(YSO) .40(l000) 550( 1025) xi5 (1050) 595~1100) 620tll50)
1 1 1 4 -I I
hour(b,c,d)
181 SLX tnhlc for specified minimum wnsilr strength somersions 10 heat treated condition. (b) Agng set trmpersnw rime. +lO. 4 min for 30min ages: +IS. 4min for I h ages: +30.4:)nin for I .5 hnpes: and +l.S. 4min ior 3.1. and I6 h ages. (5) Tog lower hardnessofprcwkd material. a set temperature up 106 “C( 10°F) higherthan specified may be used. tdl Addiuonal I to I .S h aI the specified temperature or an additional 6 to IO’T I IO to 20°F) foran additional I m I .5 h afteraging may be used 10 lowerhardness or other rnginernng properno. Source: .AhlS 175913
808 / Heat Treaters
Custom
Guide
455 (XM-16)
Chemical COITIpOSitiOn. AlSI/UNS (S-15500): 0.0s C. 0.50 hln. 0.50 Si. Il.00 to 12.50 Cr. 7.50 to 9.50 Ni. 0.040 P. 0.030 S, I.5 to 2.5 Cu. 0.8 to I.-l Ti. 0. I to 0.5 Nh. 0.5 MO iXhl is ASTM designation)
Recommended
Heat Treating
that the center of the most nitike section has reached temperature necessaq transformation and diffusion have taken place
Practice
In aerospace practice. minimum sonli time for Custom 455 is 30 min per 15 mm ( I in.). In all cases. parts are held for suffkient time to ensure
Custom 455: Required (Aerospace Practice)
Hardness
Product
Condition
After Aging
Custom 455: Tensile Strength Conversions Condition (Aerospace Practice)
ARC minimum
Badness, form
AU
H9OO
-I7
H 950 HI000
-IS 4-l
Tensile strength, Product
form
\Vroupht H’rought Source: AhlS 275913
Source: AklS
275913
to
minimum. hiPa (ksi)
Condition
1555 (22SJ
H 950
13YO(200)
HI000
and
Cast PH Stainless Custom 455: Heat Treating Practice)
Final heat treat condition(a)
Solution heat treating, set temperature, OC WI
H9OO
83OtlS3,
H 950 HI000 CH 8SO4.c)
83Ot 1525) 830(1525, none (none)
Procedures
Solution heat treating, COOlillg
Oil. polymer. water
none
(Aerospace
Aging set temperature, T (“F)(b)
Aging time, hour(b,c,d)
180 (900)
1
SlO(9SO) 540( lOOOr 455 (850~
-I -l ‘/:
(a) See table for specified minimum tensile strength sorwersions to heat treated con& tion. (b) Aging set temperatures: time. +lO. -0 tin for 30 min ages: + IS. 4 nin for I h ages:+30.4IminforI.Shages:and+JS.-Om1nfor3.4.and 16hagrs.(slTogetlo\r,rr hardness of pretested material. a set temperature up to6 “C ( 10°F) higher than specitird may be used. tdl An additional I to I .S hat the specified temperature or an additional 6 to 10°C ( IO to 20 “R form additional I IO I .S h afteraging ma) be used IO loser hardness or otherengineeting properties. (e) hlaterial in this condition is not resolution heat treated Source: AMS 175913
Steels / 809
Cast PH Stainless Steels / 809
PH 1318Mo Chemical Composition. 0.01 P.O.OO8S.O.IOSi.7.Sto8.5 to I .3S Al, 0.01 N
AISI~UNS (~13800): 0.05 c. o.?o Ni. 122Sto
13.~SCr.7.0to2.S
hln.
hlo.0.90
A predictable size change occurs 111treating PH 13-8 hlo. Contraction increases as ths aging temperature is increased, as follows:
Characteristics.
Age-hardening treatment
Forging.
H 950 HI@30 H 1050 H IOW
A martensitic (maraping) stainless that can be hardened with a single. low temperature heat treatment. Applications include forged aircraft parts Initial
Recommended
forging
temperature
is I I75 “C (2 I50 “F)
Heat Treating
Practice
Contraction, m/m (inAn.) o.ooo6 IO o.ooo4 o.ooo6 IO o.ilocJ4 06008 10 o.ooos 0.00 I2 to 0.0008
PH l3-8Mo is hardened b> heating solution treated material. Condition A. to 5 IO to 620 “C (950 to I I50 “F) for 4 h. then air cooled. Heat treatments follow (all times are at temperature): l
l
l
l
Condition A (solution treated or annealedj: Heat at 9X “C ( 1695 “F) +8 “C (IS “F) (time is dependent on section size). Cool to bsloa I5 T (60 “F) to completely transform material to martenslte. Normal practice is to hold at temperature I h. Sections under 330 cm? (36 in.‘) can be quenched in a suitable liquid quenchant. Larger sections should be air cooled Condition RH950 (precipitation or age hardened): Solution treatsd mnterial is cold treated to -74 “C t-100 “F) for 2 h minimum. Parts are air warmed to room temperature-this must be done within 24 h after solution treatment. Cold treated material is heated to 5 IO “C (950 “F) for 4 h. then air cooled Condition H950. HIOOO. Hl050. HI ISO(precipitation or age hardened): Solution treated material is heated at specified temperature +6 “C (+I0 “F) for 1 h. then air cooled Condition HI ISOh (precipitation or age hardened): Solution treated material is heated at 760 “C t 1400 “Fj +6 “C (+I0 “F) for 2 h. Air cooled then treat at 630 “C ( I I SO “F) +6 T (+ IO “F) for 4 h then air cooled
He3t treating after overaging. ln the HI I SO and HI I SOM overaped condition. this alloy will not respond to furtheragingtreatmrnt. For forging, optimum cold heading, and machining. the material must be solution beated at 925 “C t 1695 “F) afteroveraginp and before subsequent aping. Also. hardness Cabot be used to distinguish between the HI I.50 and solution treated conditions because the HI IS0 hardness falls within the hardness range for the solution-treated condition
PH13-8Mo: Typical Cryogenic and Elevated Temperature Tensile Properties. Specimen was 19 mm (0.75 in.) round bar in Hl 000 condition.
Source:
Carpenter
Technology
Corporation
810 / Heat Treaters Guide PH 13-8 MO: Soak Times for Solution Heat Treating (Aerospace Practice)
PH 13-8 MO: Heat Treating Procedures (Aerospace Practice) Fiial beat treat condition(a) H 950 HIOOO H 1025 H 1050 H 1100 H II50 H I I50M(h)
Solution heat treating, set temperatures, OC wm 925 925 925 9’5 92s 925 925
Solution beat treating, cooling(c)
( 1700) Air. oil. or polymer I 1700) lOhel0~ lS”C(60 ( 1700) “F) within I h(g) ( 1700) ( I7001 ( l7CM.N I 1700)
Agingset temperature, OC (“F)(d) SlO(9SO) S40(1000) SSO(102S) 565 ( 1050) 595 (I 100) 62O(llSO) (h)
Product Aging time, bour(d.e,f)
;t 4 4 4 4 (h)
la) See table for specified minimum tensile strength conversions IO heat neared condition.(h~Seetableforsoaktimes.(c~Airmeansairora~osphere.(d)~me.+lO.-Omin for 30 min ages: + 15. -0 min for I h ages: +30 min. -0 min for I .S h ages: and +15 min for3.1.and I6 hages. (e)Toget louerhardness forpretes~edmarerial,aset remperature up IO 6 “C ( IO “F) higher man specitied may be used. (0 An additional I to I .S h at the specifiedremperamreoranadditional6 IO IO”Cil0 to 20 “F) foranadditional I to I.5 h after aging ma) be used to lower hardness or other engineering properties. (g) Artificial means may be used to cool below ambient [emperature when necessary 10 get below 3O”C(9O”F)orbelow 15”C(60°F).(h)H Il50Misaninrermediatesoftcondition that must be re-solution heat ueated to obtam a different tinal condition. To obtain H I ISOM. solution heat treat. then heat al 760 ‘C ( I-100 “F). air cool below 30 “C (85 “F) for 2 to 2.5 h, plus 620 “C ( I IS0 “F) for 4 h. Source: AhlS 27.5913
Minimum soak time, mh(rqb)
form
All
30 per 25 mm ( I in.)(a)
(alTime. +10.-O.(b) Inallcases.pansare held forsufficient timetoensuretharthecenter of the most massive section has reached temperawe and the necessary ttansformation and diffusion ha\ e taken place. Source: AMS 275913
PH 13-8 MO: Tensile Strength Conversions Condition (Aerospace Practice) IUhimum Tensile strength. MPa (ksi)
Form(a) B. B. B. B. B. B.
F.T. F. T. F. T, F. T. F.T. F. T,
Bi. Bi. Bi, Bi. Bi. Bi.
P P P P P P
to
Condition
lS20(220) 1415 (205) 1275 (185) 1210(17S) 1035(150~ 930(135J
H 950 HI00 H 1025 H 1050 H II00 H 1150
(a) B. bar: F. forging; T. tubing: Bi. billet: P, plate. Source: Ah4.S 2759/3
PH 13-8 MO: Required Hardness After Aging (Aerospace Practice) Product
form
All
Source: AhlS 275913
Condition H 950 HICOO H I025 H 1050 H II00 H IISO H I l50M
Ehrdocss.
ERC
45 to 49 43 to 47 41 to46 401046 34 to 42 30 IO 38 28 to 36
Heat Treating Chemical
Composition
Gray irons usually contain 2.5 to JCC carbon, I to 3% silicon, and additions of manganese (as low as 0. IO 9 in ferritic gray irons and as high as 1.2% in pearhtics). Sulfur and phosphorus are present in small amounts as residual impurities.
General
All strength properties,
Specific User properties wear reststance.
Flake graphite IS dispersed in a matrix ti ith a microstructure deterrnmed by composition and heat treatment. hlatrx structurrs resulting from heat treamlent can vary from ferritepearlite to t2mpend martensitc. Standard compositions ar2 pressnkd in adjoining tables.
Characteristics
ASTM A 48 classifies gray irons in temrs of tsnsils strength. but m many applications strength is not the critical property. Lou stmngth grades. for example. are superior performers whrre resistance to h2at checking is the prime property. According to the ASTM ratmgs, class 20. th2 Iovvest strength grade, has a minimum tensile strength of I-IO hlPa (20 ksij; vvhilr class 60. the highest strength gadr. has a tensik strength of -llO MPa (60 ksi). Generally it can be assumed that the following properties improve with increasing tensile strength: l
of Gray Iron
including
those at elevated
l l
hlodulus of elasticity Resistance to wzar Convrrsely.
l l l l
some properties
deteriorate
hlachinability Resistancz to thermal shock Damping capacity Castability-in temrs of ability
with decreasing
tensile strength:
to produce thin sections
temprratures
Characteristics of interest include
impact resistance,
machinability,
and
Impact resistance. Gray iron is not mcommendsd where high impact resistance is needed. Two methods of tcstinp for this property are given in ASTM A 327. Machinability. Most gray iron castmgs have better machinability than most other irons ofequivalent hardness, as well as that of I irtually all steel. ln addition. substantial gains m machmability are available through annealing (see heat treating sectton). Wear. Gray iron. in both the as-cast and hardened conditions. is used widely for machine components that must stnnd up to various types of wear. Hardening provides the most sipnikant Improvement m resistance to nomral wear. and is specified for maximum resistance to wear in severe wear applications. Dimensional Stability. The most demanding applications at elevated temperatures are those in which dimensional accuracy is important. Dimensional stability is degraded as temperature and exposure time increase. This property is affectrd by factors such as growth. scaling, and creep rate. Growth. Breakdown of pearlite to ferrite and graphite IS the cause. The remedy: additions of alloying elements such as coppzr. molybdenum. chromium, tin. vanadium, and manganrse. They stabilize the carbide structurr. Scaling. In a series of tests, temperature had a greatzr effect than time at temperature. For example. the extent of scaling at 350 “C (660 “F) over
a period of I I .S years was,-! mgkm’. while exposure of 64 weeks at 500 ‘C (930 “F) was I6 mE/cm-. In the sam2 study, it was found that differences in alloy contrnt had only minor 2ff2cts on scaling. Creep. This propsrty is improved with additions of chromium and molybdenum. When parts operate at temperatures undzr 480 “C (895 “F). two mom sources of dimensional accuracy must be considered: residual stresses and machining practice. Residual stresses. Residual strrsses a-2 present in all castings in the as-cast conditton. but only a small percentage are strrss relieved before machining-chiefly thosr requiring exceptional dimensional accuracy, or those with a combinatton of high or nonuniform stress associated with low section stilkss or an abrupt change m section size. Castings of class 40. 50. and 60 iron are more likely to contain high residual stresses. Machining practice. Because the surface of a casting is often the main sit2 of rzsidual str2sses, a large amount of stress is relieved by rough machining. If before tinal machining, th2 casting is relocated in the machine carefully and supported in cool fixtures, acceptable dimensional accuracy usually is obtained in the finished workpiece. Annealing. This is another way of improv ing machinability (discussed in th2 next section).
Recommended and Processing
Heat Treating Sequences
Practices
Annealing and strsss relizving are the two most common methods of heat treating gray iron castings. Annealing is the most frequently used.
Heat Treating Other suitable processes include normalizing, hardening and tempering. austempering, and martempering. Flame hardening and induction hardening are alternatives to electrically heated, gas. or oil-fued furnaces and salt bath processes. Both annealing and hardening have disadvantagrs: l
l
Ann~alirrg-this process improves machinability. but there is a price: properties are reduced approximately to the next lower grade of gray iron Hczrdfning-Hardening and quenching from elevated temperaturss strengthen castings, but the process ordinarily is not used for this purposr in commercial practicr. Th2 more economical rout2 to the desired result is to reduce silicon and total carbon, or by adding alloying el2ments. When gray iron is quenched and t2mpered. the common reason is to bzsf up resistance to wear and abrasion by mcrensing hardness with a structure consisting of graphite embedded in hard martensite
Annealing Practices. Gray iron nomlally treatments: ferritizing tizing annealing.
annealing.
medium
is subjected to on2 of these (or full) annealing. and graphi-
Ferritizing process. It generally is unnecessary IO heat unalloyrtd or low alloy gray iron to temperatures above the transition range when the sol2 purpose is to convert pearlitic carbide to ferrite and graphite for improved machinability. The recommendzd f2rritizing annsaling temperature for most gray irons lies between 700 to 760 “C ( 1290 to l-i00 ‘F). When stress relief is the objective. slow cooling to room temperature is recommendzd. A cooling rate rangmp from I IO “C (230 “F) per h to 290 “C (555 “F) per h is satisfactory for all but the most complrx castings. Medium (full) annealing. This treatment is the choice when a femtizmg anneal would be ineff2ctive because of high alloy content of a particular iron. Annealing usually is perfomred at tempsratures between 790 to 900 ‘C (1155 to 1650 “F). Holding times usually are comparabl2 to those for the ferritizing process. Howev2r. when temperatures are at the high end of the range. castings must be cooled slowly through the transformation rang2 from approximately 790 to 675 “C ( l-t55 to IX5 “FL Graphitizing annealing. To break down massive carbides to prarlite and graphite with reasonable speed, temperatures of at least 870 “C (,1600 “F) are required. With each additional 55 “C ( I30 “F) incrzment in holding temperature. the rate of carbide decomposition doubks. General practtce IS to use holding temperatures of 900 to 955 “C ( 1650 to I750 “F). Holding time at temperature can range from a few minutes to several hours. Cooling rate depends on end use. For maximum strength and w2ar resistance, castings should be air cooled from the annealing temperature to approximately 540 ‘YY (1000 “F) to promote the formation of a pearlitic structure. For maximum machinability. castings should be furnace cooled to 5-10 “C (1000 “F), and special care should be taken to ensure slow cooling through the transformation range. In treating for maximum strength and wear resistance and maximum machinability, cooling from 540 ‘C (1000 “F) to approximately 390 ‘C (555 “F) at a rate of not more than I IO “C (730 “F) per h is recommendsd to minimtze residual stresses. Gray iron m the as-cast condition contains residual stresses. Esception: much of the solidification stress is rrmoved when the iron is cooled in the mold. The stress relieving temperature usually is w2ll below the range for thr transformation of pearlite to austenite. For maximum stress relief with minimum carbide deposition in unalloyed irons. a temperature range of S-IO to 565 “C (1000 to 1050 “F) is desirable. When almost complete stress relief (>85%) is required in unalloyed iron, a minimum temperanus of 595 “C (I I05 “F) can be used. Rate of heating. For stress relief. the heating rate dzpends on ths sizs and shape of the castmg. However. the rate. except for the most complex shapes. is not especially critical. Rate of cooling. Slow cooling from the stress-relieving temperature. at least in the upper temperature rangs. is essential. The general recomm2ndation is furnace cooling to 3 IS “C (600 “F) or lower, before air cooling. When designs are intricate. it may be advisable to continus fumacs cooling until a temperature of approximately 95 “C (705 “F) is reached.
Iron Casting
and P/M Steels / 817
Normalizing Practices. Gray. iron is nomlalized by being heated to a temperanus above the transfomuttton range: held at this temperature for a period of npproxtmately I h per Inch of maximum section thickness: then cooled m still air to room temperature. Normalizmp senes a variety of functions. including the enhancement of mechanical properties. such as hardness and tensile strength: and the rrstoration of as-cast properties modified in other heating processss. such as prnphitizing annsnling or the prrhsnting and postheating associated with welding. The tempernrurr rang2 for normalizing is approximatsly 885 to 925 “C t 167-S to 1695 “FL Tensils strength and hardness dspend on combinsd carbon content. pearlite spacing tdistancc betw 22n c2mentite plates), and graphite morpholOP.“. Hardness can b2 partially controlled by allowing castings to cool in the furnacs to a tcmperaturz bslow the normalizing temperature.
Hardening
and Tempering
Practices
hkchanical properties. strength and wear rzsistance tn particular. are Improved by thes2 treatments. Hardened and tempered gray iron has approximately five times mars rssistnnct: to wear than pearlitic gray iron. Furnace or salt bath hardening have a much broader application rang2 than those of Flame and induction hardening. In the latt2r two processes. a relativeI\ high total carbon content IS weded because of the extremely short time available for the solution of carbon in aust2nue. By contrast. in furnace or salt bath hardsning. a casting can be held at a temperature above the transformation range for as long as necessary. An unalloyrd pray iron with a combined carbon content of 0.60%, has hiphsr hardcnability than a carbon steel with the same carbon content. Reason: the gray iron has a higher silicon contznt. The hardcnability of gray iron is increased via the addition of a variety of alloving elements: manganese. nisk2l. copper. and molybdenum. Also, chron&m~ contributes to carbidr stabilization. which is especially important in flam2 hardening. Chromium does not influence the hardenability of gray iron. Hardening cycle. In nustenitizing. castings are heated to a temperature high enough to promots thz formation of austeniv: held at that temperature until the desu2d amount of carbon has bern dissolved; then quenched at a suitabl2 rate. Heating temperaturr is drtzmrin2d by the transformation range of a given gray uon. A formula for determining the approximate At transfomration temperature of unalloyed iron is. “C~730+78.0~~ Sir-25.Ot%hlnt ‘-F. 131S+riO11’iS1)-3S.Ot~hln, Chromum~ raises the transformatton range of gray iron. Castings should b2 treated through th2 lowsr temperature rang2 slowly to avotd cracking. At t2mp2ratures in a rang2 of 595 to 650 “C (I I05 to I200 “F) abovc the stwss relirv tng range, heatmg may not be as rapid as dssirsd. Quenching. hlolten salt and oil are the most frequently used quenchants. Watzr prnsrally is not suitablt: for quenching furnace-heatrd gray iron: heat IS rxtractsd so rapidly that distortion and cracking In all castings are likzly except those simple in drsign. Ib’atcr-solublz polymer quenchants a-2 an option to provid2 cooling rates betwen those of water and oil and to minimize themral shock. Air is the least sever2 quenching medium. But both unalloyed and low alloy gray Iron can’t be air quenched because the cooling rate is not fast rnough to form martensitz. Air. hovvever. is frequently the most desirable cooling method for high alloy grades. Tempering practice. Castings usually are tempered after quenching at temp2raturzs well bclovv the transformation rang2 for approximately I h per inch of thichest wction. Hardness decreases with tempering. while. usually. strength and toughness rise.
818 / Heat Treaters
Guide
Austempering and Martempering Practices. The maximum hardness obtainable with austempering usually is less than that available in martempering. However. the difference may be largely offset during the tempering treatment usually required following martempering. But in comparison with conventional oil quenching, less distortion and growth are experienced in austempering and martempering. Austempering Process. In this treatment. gray iron is quenched from a temperature above the transformation range in a hot quenching bath, and is maintained in the bath at constant temperature until the austempering transformation is complete. Quenching usually is in salt, oil, or lead baths at temperatures in the range of 230 to 425 “C (445 to 795 “F). When high hardness and resistance to wear are specified, quenchant temperature usually is held between 230 to 290 “C (-l-IS to 555 “F). Holding time for maximum transformation is determined by quenching bath temperature and composition of the iron. The effect of the latter on holding time may be considerable. Alloy additions such as nickel. chromium, and molybdenum Increase the trme required for transformation. Martempering Process. In this instance. martensite is produced minus the high stresses that usually accompany its formation. Martempering is similar to conventional hardening, except that distortion is minimized. Also, martensite retains its characteristic brittleness. For this reason. martempered castings are almost always tempered. Castings are quenched from above the transformation range in salt, oil, or lead baths; held in the range at which martensite forms [?OO to 260 “C (390 to 500 “F) for unalloyed irons] only until the casting has reached the bath temperature; then it is cooled to room temperature. For a wholly martensitic structure. the casting must be held in the hot quenching bath only long enough for it to reach the temperature of the bath. If dimensional accuracy is important, allowance for growth must be made prior to heat treatment. Some distortion. in comparison with growth. occurs during mat-tempering. Conditions that may promote excessive distortion are: residual stresses from casting, machining, or rapid cooling during previous heat treatments; insufficient time for establishing equilibrium at the austenitizing temperature: and drafts during air cooling after castings have been removed from the quench tank. Flame Hardening Process. This is the surface hardening process most often applied to gray iron-both unalloyed and alloyed grades. As a rule. combined carbon content should be in the range of 0.50 to 0.70%, but irons with as little as O.-IO%, combined carbon can be flame hardened. Generally, the process is not mcommended for irons containing more than 0.80% carbon because they can crack. For maximum hardness, it is advisable to use an iron containing as little total carbon consistent with the production of sound castings free from any likelihood of cracking. Because silicon promotes the formation of graphite and of a low combined carbon content, a relatively low silicon content is advisable, i.e.. silicon content should not exceed 2%, and manganese content should be held in the range of 0.80 to I .OO~ to increase carbon solubility in austenite. Room-temperature hardness of gray iron after normalizing. Effect of temperature at start of aircooling on hardness on normalized gray iron rings 120 mm (4% in.) in outside diameter, 95 mm (3% in.) in inside diameter, and 38 mm (1% in.) in length
In addition, gray iron should be as free as possible from porosity and from foreign matter such as sand or slag. Porosity and even small inclusions can produce a rough surface or cause cracking after hardening. In general, alloyed gray irons are easier to flame harden than unalloyed grades, partly because alloys have greater hardenability. Maximum hardness of nonalloys is obtained with a composition of approximately 30’0 total carbon. I .7% silicon, 0.60-0.800/b manganese. Hardnesses range from 400 to 500 HB. Stress relieving. When practical or feasible economically, flame hardened castings are stress relieved at I50 to 200 “C (300 to 390 “F) in a furnace, in hot oil, or by passing a flame over the hardened surface. Benefits are minimized distortion or cracking and an increase in the toughness of the hardened layer. Hardness. The surface of a flame hardened casting is typically lower than that of the metal immediately below the surface. Surface hardness often can be raised by heating in the range of I95 to 250 “C (385 to 480 “Ft. Fatigue strength. This value is usually improved because the treatment induces compressive stresses at the surface. Quenching. Quenchants are selected on the basis of the flame hardening method used: l
l
Progressive mefhod: only nonflammable media are used, such as water, soluble oil mixtures, and water solutions of polymers. Conventional oil can’t be used because of the fiie hazard Spar tmrdtwing or spinning melhods: conventional quenching by immersion in hot oil is used. In these methods, the flame head is withdrawn from the part prior to quenching
For best results in using water. water temperatures should be around 30 “C(8S”F). To suppress cracking, lower quenching rates are obtained by using 5 to 15% soluble oil mixtures. compressed air. or compressed air and water at low pressures. Air quenching is especially suited for highly alloyed irons because of their susceptibility to cracking. Induction Hardening Process. Hardnesses obtained are influenced by carbon equivalent (G C + 1/36 Si) when this value is measured by conventional Rockwell tests. The amount of graphite in the microstructure can have a negative effect on surface hardness: the higher the volume of graphite, the lower the surface hardness. Induction hardening causes less distortion than that experienced in parts quenched after treatment in a furnace.
REFERENCES I. C.V. White, Gray hon. Vol I, ASM Handbook. p 12-32 2. B. Kovacs, Heat Treating of Gray Irons, Vol 4, ASM Handbook, I, 670-68 I
Effect of austenitizing time on room-temperature hardness of quenched gray iron specimens. Specimens were 32 mm (1% in.) in diameter by 19 mm (3/4 in.) in thickness
Heat Treating
Effect of annealing on tensile strength of class 30 gray iron. Specimens were arbitration bars from 31 heats. Bars were annealed at 925 “C (1695 OF)for 2 h plus 1 h per 25 mm (1 in.) of section over 25 mm (1 in.), and cooled from 925 to 565 “C (1695 to 1050 “F) at a rate not to exceed 160 “C (285 “F) per h. Cooling continued from that level to 200 “C (390 “F) at a rate not to exceed 130 “C (230 “F) per h; bars were then air cooled to room temperature
Iron Casting
and P/M Steels / 819
Effect of isothermal transformation temperature on hardness of austempered gray irons. Holding times were sufficient to complete transformation
COtWc?rSiOn of as-CaSt pearlitic structure of unalloyed gray iron to ferrite and graphite by annealing. (b) Annealed 1 h at 760 “C (1400 “F); 120 HB. Magnification, 500x
MiCrOStrUCtUrSS.
(a) As cast; 160 HB.
Distortion in gray iron cylinder liners after martempering and after conventional oil quenching. Before being measured, (390 “F)
liners were furnace tempered
for 2 h at 200 “C
820 / Heat Treaters
Guide
Effect of tempering temperature on gray iron. (a) to (c) Changes in mechanical properties of hardened low-silicon unalloyed gray iron. (d) Hardness of gray iron specimens quenched in oil from 870 “C (1600 “F) and tempered. Each point on this chart represents an average of five hardness readings
Typical hardness hardening
Types of graphite flakes in gray iron (AFS-ASTM). In the recommended of 100x. They have been reduced to one-third size for reproduction here
gradient
produced
in gray iron by flame
practice (ASTM A247), these charts are shown at a magnification
Heat Treating
Effect of stress-relieving cated temperatures
Stress-relieving
Iron Casting
and P/M Steels / 821
temperature on hardness of gray irons. Bar specimens 30 mm (1.2 in.) in diameter were held for 1 h at indi-
and then air cooled
time and temperature on degree of stress relief obtained in low-alloy gray irons. Table shows compositions
ligible effect of maximum stress-relieving
conditions on hardness
and neg-
822 / Heat Treaters
Microstructures.
Guide
Structure of class 35 iron, as-cast (left) and after annealing
Location and magnitude castings
Effect of Carbon Equivalent on Surface Induction-Hardened Gray Irons Composition, +(a) CllhOll C Si equivalent(b)
Hardness
of
Eardness ARC, converted from Rockwell As read 30-N hlicrohardness
Effect of Annealing 35 Gray Iron
on Hardness
Condition
hlPa
I.SO I .68 I .64 I .59 1.80
3.63 3.70 3.74 3.87 1.02
SO 49 48 47 46
50 50 SO 49 47
61 57 61 58 61
3.46 3.52
2.00 2.14
3.13 4.23
43 36
45 38
59 61
(a) Each iron also contained 0.50 IO 0.90 Mn. 0.35 IO0.55 Ni, 0.08 to 0. IS Cr. and 0. IS IO0.30 MO. (b) Carbon equivalent = ‘%C + I/,%, Si
and Strength
of Class
ksi
Eardness, ml
268 165
38.9 23.9
217 131
Tensile strength AS-GLSt
3.13 3.14 3.19 334 3.42
of residual stresses in two gray
Annealed
Compositionof iron: 3.30%. tomI C. 2.224 Si. 0.027%. P,O.l8% S,O.61% Mn. 0.03% Cr. 0.034 Ni, 0. I-!!% Cu. hlo nil. Annealing treamwnt consisted of I hat 775 “C (1425 “F), followed by cooling in the furnace to 540 “C ( 1000 “F)
Heat Treating
Hardenability
Data for Gray Irons Quenched
Iron Casting
and P/M Steels / 823
From 855 “C (1575 “F)
See adjoining Table for compositions. Distance fhm quenched end L/la mm increments 3.2 6.4 9.5 12.7 15.9 19.0 22.2 25.4 28.6 31.8 34.9 38.1 41.3 44.4 47.6 50.8 54.0 57.2 60.3 63.5 66.7
2 4 6 8 10 12 I4 I6 I8 20 22 24 26 28 30 32 34 36 38 40 42
Plain iron
MOW
54 53 50 43 37 31 26 26 25 23 22 22 ?I 20 I9 I7 I8 I8 I9 22 20
56 56 56 54 52 51 51 49 46 46 45 43 43 40 39 39 36 40 38 38 35
Elardness,ARC Ni-Mo MO(B) 53 5’ 52 51 50 49 46 45 45 4-l 43 4-l 4-i 41 40 40 41 40 37 36 35
5-l 51 53 53 52 52 52 52 52 51 17 17 47 15 15 -t5 4-i 45 45 -I? 31
Compositions
of Gray Irons Listed in Adjoining
Table
Iron
TC
CC(a)
Mn
Composition, % Si Cr
Plain WA) MO@) Ni-Mo Cr-Mo Cr-Ni-Mo
3.19 3.22 3.20 3.22 3.2 I 3.36
0.69 0.65 0.58 0.53 0.60 0.6 I
0.76 0.75 0.64 0.66 0.67 0.74
1.70 I .73 1.76 2.02 2.2-l I.96
(a) CC. combined carbon. (b) GC, graphirecarbon
2.50 2.57 2.62 2.69 2.61 2.75
0.03 0.03 0.005 0.02 0.50 0.35
Cr-Mo
Cr-Ni-Mo
56 55 56 5s 55 54 5-I 54 53 SO 50 49 47 47 44 -II 38 36 31 35 32
55 55 54 54 53 53 52 53 52 51 50 50 49 48 50 47 46 45 46 46 45
Ni
MO
P
s
Tl-Xe I.21 0.06 0.52
0.013 0.47 0.48 0.52 0.52 0.47
0.216 0.212 0. I87 0.114 0.ll-t 0.158
0.097 0.089 0.054 0.067 0.071 0.070
Heat Treating Chemical
Ductile
Composition
Standard compositions and general uses of ductile iron are listed in an accompanying table. Most compositions for standard grades are hased on properties. i.e., strength and/or hardness: composition IS loosely specified or made suhordinate to mechanical properties. Ductile iron is now accepted internationally as the name for these irons. It is also called nodular iron or spheroidal graphite ISG). The unique feature of this iron is the presence of graphite in the form of tin) spheres. (nodules). See accompany inp microstructures. Microstructures are grouped into [no hrond classes:
The ferrite structure usualI> is produced in annealing. normalizing, normalizing and tempering. or quenching and tempering. The austenitic structure is produced by austempering, an isothermal process resulting In a product known as austempered ductile iron (ADI). Stress relief annealing does not involve major microstructure transformations, while selective surface treatments. i.e., flame and induction hardening. do in selectively controlled areas of a casting. Similar Cast Irons (U.S. and/or Foreign). Accompanying tables provide information on: l
l
l
Those in which the major iron-hearing matrix phase is the thermodynamicallq stable, hody-centered cubic (ferrite) structure Those with a matrix phase that is a metastahle. face-centered. cubic (austenite) structure
General
l
l
Mechanical properties and typical applications of standard ductile irons (ASThl, ASME, SAE-AhlS specifications) Ductile iron property requirements of various national and international standards (ISO. ASTM. and SAE) Some tentative specifications for austempered ductile iron (U.S., Swiss, and Great Britain)
Characteristics
Basic differencss between ferritic and austenitic ductile iron are sxplained in an nccompan) ing continuous cooling transformation diagram (CCT), along with cooling curves for furnace cooling. air cooling. and quenching. Examples of the subsequent microstructures are shown in an accompanying figure. A second figure is an isothermal transformation (IT) diagram showing a processing sequence for austempering. The relatively high strength and toughness of ductile iron give it an advantage over gray iron and malleable iron in many structural applications. In addition. because ductility does not require heat treatment to produce graphite nodules. as does malleable uon to produce temper-carbon nodules. it can compete with malleable iron even though it does require a treatment and inoculation. Ductile iron has many applications requiring strength and toughness combined uith good machinability and low cost. Ductile iron has about the same machinability as gray iron of similar hardness. At tensile strengths up to approximately 550 hlPa (80 ksi) ductile iron has better machinability than that of cast mild steel. At higher hardnesses, differences are less pronounced. Special materials and techmques &areavailable to repair weld ductile tron or to join it to itself and to other materials such as steel. gray iron. or malleable iron. Special precautions are needed to get optimum properties in the ueld metal and in the heat affected zone. The main obJective is to avoid the formation of cementite in the matrix material. which makes the LieId zone brittle. Another must is to retain graphite in its nodular form. Martensite or tine pearlite can he removed hy tempering.
Recommended and Processing
Iron
Heat Treating Sequences
Practices
Ductile irons are heat treated prim‘arily to create matrix microstructures and associated mechanical properties not readily obtained in the as-cast condition. The most important heat treatments are:
Stress relieving-a low temperature treatment to reduce or relieve internal stresses remaining after casting Annealing-to improve ductility and toughness, to reduce hardness. and to remove carbides Normalizing-to improLe strength while retaining some ductility Hardening and tempering-to increase hardnesses or to improve strength and raise the proof stress ratio Austrmperinp-to produce a microstrw%re that provides high strength uith some ductility and good resistance to wear Surface hardening-to produce selective we;LT resistant surfaces with flame. mductlon. and laser processes. for example Stress Relieving Ductile Iron. IVhen not otherwise heat treated, complex enpineermg castings are stress relieved at 510 to 675 “C (950 to I145 “F). Temperatures at the lower end of the range are adequate in many applications. Those at the higher end eliminate virtually all residual stresses, hut at the cost of some reduction in hardness and tensile strength. Recommended stress-relies ing temperatures for different types of ductile iron are as follows: l Unalloyed: . Low alloys: l High alloys: l Austcnitic:
510 to 565 ‘C (950 to 1050 “F) 565 to 595 “C (1050 to I IO5 “F) 595 to 650 “C ( I I OS to I200 “F) 620 to 675 ‘C ( I I.50 to I245 “Fj
Cooling should he uniform to avoid the reintroduction of stresses. Practice is IO furnace cool to 190 “C (555 “F), then air cool, if desired. Austenitic iron can he uniform)! air cooled from the stress relieving temperature. Annealing Ductile Iron. Castings usually are given a full ferritizing anneal for good machinability when high strength is not required. The treatment produces ASThl grade 60--IO- 18. For good machinability, manganese. phosphorus, and molj bdenum should he as low as possihle. Recommended practice for castings n ith differing alloy contents and for castings with and ~tithout eutectic cnrhides follows:
Heat Treating Ftrll anneal for unalloyed ? to 34 Si irorl that does not contain etrtectic carbide: heat and hold at 870 to 900 “C (1600 to I650 “F) for I h per inch of section. Furnace cool to 345 “C (655 “FI at 55 “C (I 00 “F) per h; air cool Full anneal with cm-bide present: heat and hold at 900 to 925 “C i I650 to 1695 “F) for 2 h mimmum-longer for heavier sections. Furnace cool to 700 “C ( I290 “FI at I IO “C (200 “F) per h. Hold 2 h at 700 “C ( 1290 “F). Furnace cool to 315 “C (655 “F) at 55 “C (100 “F) per h. Air cool Subcritical ormeal to cornwt pearlite to ferrite: heat and hold at 705 to 720 “C (300 to I330 “F). I h per inch of section. Furnace cool to 345 “C (655 ‘F) at 55 “C (100 “F) per h. Air cool
Hardenability
of Ductile Iron. This is an important
parameter for detcmining the response of a given gray iron to normalizing. to quenching and tempering. or to austemperinp. Normally this value is determined bj the Jommy test: a standard bar [25.-l mm ( I in.) in diam bj 100. I6 mm (4 in.) in length] is austenitized and water quenched at one end. Normalizing Ductile Iron. In this treatment (austenitizing followed by air cooling). tensile strength is improved considerably: and the process may be used to produce ASTM type 100-70-03 iron. Normalizing temperatures usually range between 870 to 910 “C ( I600 to I725 “FJ. Standard time at temperature is I h per inch of section. or a minimum of I h. Longer times may be needed when alloys contain elements that retard carbon diffusion into austenite. Normalizing sometimes is follo\sed b) tempering to obtain a desired hardness and to relieve residual stresses that develop in air cooling m hen areas of a casting with different section sizes cool at different rates. Also, tempering after normalizing is a \\ay to obtain high toughness and resistance to impact Tempering usually conststs of reheating to 325 to 650 “C (795 to I200 “F) and holding at the desired temperature I h per mch of cross sectlon. Quenching and Tempering Ductile Iron. Prior to quenching and tempering. commercial castings normally are austenitized at 845 to 925 “C (IS55 to 1695 “F). To minimize stresses and quench cracking. oil is the preferred quenchant. Water or brine may be used H hen shapes are simple. Oil heated to 80 to IO0 “C ( I75 to 2 IO “F) is used to avoid cracks when castings are complicated. Castings should be tempered immediateI> after quenching to relieve quenching stTesses. Tempering in the range of 425 to 600 “C (795 to I I IO “F) reduces hardness. the amount depending on alloy content, initial hardness. and time. Austempering Ductile Iron. An austempered structure of austenite and ferrite provides optimum strength and ductility. The austempered matrix is responsible for a significantly better tensile strength-to-ductility ratio than is possible with any other grade of ductile iron. Production of these properties calls for careful attention to section size and to time/tsmperature exposure during austenitizing and austempering. As section size increases, the rate of temperature change between the austenitizing and austempering temperature decreases. Quenching and austempering techniques include. l l l l
Hot oil quenching (< 240 “C. or 465 “F. only) Nitrate/nitrite salt quenches Fluidized bed quenching (only for small, thin parts) Lead baths (for tool-type applications)
Austenitizing temperatures between 8-U to 925 “C (I 555 to I695 “Fj are normal: and times of about 2 h have been shown to recarburize the matrix fully. Properties obtained in austempering \ary with temperature and time. Effects of temperatures ranging from 240 to 440 “C (465 to 825 “F) on yield strength. tensile strength. and impact strength are shown in an accompanying figure. Reaching maximum ductility at a given temperature is a time sensitive function. After maximum ductility is attained. further austempering reduces ductility. In an accompanying figure. this relationship is shown at times of temperature ranging from 8 to approaimatel) 200 min. Tempera-
Iron Casting
and P/M Steels / 825
tures run from 357 to 400 ‘C (675 to 750 “Fj. Typical \ary from I to-l h.
Surface
Hardening
This iron readily l l l l
of Ductile
responds to a ~ariet!
austempering
times
Iron of surface hardenmg processes:
Flame hardening Induction hardening Nitriding-comentional. salt bath, and plasma processes Laser or plasma torch hardening
Pearlitic types of ductile iron. XSThi 80-60-03 and 100-70-03, are preferred for hardening applications because all of these treatments take place in seconds. Lrons that do not contain free femte in their microstructures respond almost instan!ly to name or induction heating and need little holding time at their austcnmzing temperatures to become fully hardened. Given proper technique and temperature control between 815 to 900 “C t IS55 to I650 ‘F), surface hnrdnesses that can be expected with different matrices are: l
l
l
l
Fully annealed t ferritic) iron. water quenched behind the tlame or induction coil. 35 to 45 HRC Predominantly ferritic ipanlj pearlitic) iron. stress relieved prior to heating. self-quenched. 40 to 15 HRC Predominantly ferritic (partI> pearlitic) iron, stress relieved prior to heating. Water quenched. SO to 5S HRC hlostly pearlitic iron. stress relieved before heating. water quenched. 58 to 62 HRC
Induction hardening. Response depends on the amount of pearlite in the matnx m the as-cast. normalized. and normalized and tempered conditmns Percentages of pearlite or ferrite required in each condition are: As-castcorlditiorl-minimum
of 50ci pearlite to get satisfactory hardening with heating cycles of 3.5 s and longer at hardening temperatures of 955 to 980 “C t, 1750 to 1795 “F). Castings can be hardened at higher temperatures M hen structures conrain less pearlite. but at the risk of damaging surfaces. \Vith pearlits aboLe 508,. hardening temperatures may be reduced m ithin the range of 900 to 925 “C ( I650 to I695 “F) Norma/i:ed rorrditiorl-for quenching cycles of 3.5 s and longer. temperatures of 945 to 980 “C t 1750 to 1795 “F). 508 pearlite in a prior structure is a minimum Qlrerrched orrd /enl~ert~d-the response is excellent over a wide range of microstructures containing up to 9% ferrite. Quenching and tempering. as a prior treatment. pemlits a lower prior hardness, but there is a risk of distortion and quench cracking
Nitriding Ductile Irons. Case hardening can be carried out with conventional plasma.
nitriding.
or in liquid
salt baths based on cyanide
salts. or in a
Conventional process. Nitrogen diffuses into surfaces at temperatures ranging approximately 550 to 600 “C ( 1020 to I I IO “F). Ammonia usually is the source of nitrogen. A surface layer. typically white and featureless in an etched nucrostructure. of approximately 0. I mm (0.00-I in.) deep is produced. Surface hardness is close to II00 HV. Additions of alloying elements can increase hardness, i.e., OS to 1% Al, Ni. or MO. Advantages of nitriding in addition to very hig,h hardnesses. are: better resistance to \\ear and scuffing, plus improved fatigue life and resistance to corrosion. Salt bath treatment. Temperatures are lower. but case depth is less than that obtained H ith the con\ entional process. Nitriding in plasma. A recent development. At this time, the need for special equipment and processing costs may be deterrents to usage. Laser/plasma torch processes. This technology makes it possible to produce tiny. remelted areas on selected surfaces of castings. The heated area rapidly solidities because of the self-quenching effect of the mass of the casting. The result is a white iron structure that is substantially free of graphite and has a combination of high hardness and resistance to wear.
826 / Heat Treaters
Guide
The area heated by a 2.5 kw laser is typically 1.5 mm (0.06 in.) in diameler by 0.5 IO 1 mm (0.02 to 0.08 in.) in depth. Hardness of approximately 900 HV is produced without cracking.
REFERENCES I. L.R. Jenkins and R. D. Forrest. Ductile Iron, Vol I, ASM Handbook 2. K.B. Rundman, Heat Trealing of Ductile Iron, Vol4. ASM Handbook
Microstructures. Microstructures of ductile iron. (a) As-cast ferritic. (b) As-cast pearlitic; hardness, 255 HB. (c) Fertitic, annealed 3 h at 700 “C (1290 “F). (d) Pearlitic ductile iron oil quenched and tempered to 255 HB. All etched in 2% nital. 100x
Heat Treating
ASTM Standard
A 897-90 and A 897M-90 Mechanical h4Pa
ksi
80
850
IO0
I50 700
125
175 850 . II00 . 1300
200 l4Cil 230 1600
I55 185
and P/M Steels / 827
Ductile
Iron
impact(a) J
IO IO 7 7 4 4 I I (b) (b)
550
1050 . 1200
of Austempered
Elongation, %
ksi
I25
125-80-10 850-550-10 150-100-7 IO50-70-7 175-125-4 I200-850-4 200-155-l I-u10-IlO@ 230-185 1600-1300
Requirements
Yield (min)
Tensile (min) MPa
Grade
Property
Iron Casting
Eardnes, ft
Ibf
WC) 269-32 I 269-32 I 302-363 302-363 34 I-444 341-444 388-477 388-477 444-555 444-555
75 100 60 80 45 60 ‘5 35 (b) (b)
(a) Unnotched Charpy bars tested at 72 = 7 “F(22 = 4 “C). The values in the table are a minimum for the average of the highest three test values of four tested samples. (b) Elongation andimpactrequirememsarenotspecitied. Althoughgmdes200-155-l. 1400-I 100-l. 230-185,1600-1300areprimarily used forgearand wearresistanceapplications,grades200I55- I and l40@ I IOO- I have applications where some sacritice in wear resistance is acceptable in order to provide a limited amount of ductility and toughness. (c) Hardness is not mandatory and is shown for information only
Compositions
and General Uses for Standard
Specification
Grade or class
No.
Grades of Ductile lj+al
lJNC
TCb)
Si
MO
Iron
composition, P
S
Description Ferritic;
60-30-18
F32800
3.OOmin
80-60-03
F34100
3.OOmin(c)
ASTM
60-40-18(d)
F32800
65-45-12(d)
F33100
80-55-06(d)
F33800
100-70-03(d)
F34800
120-90-02(d)
F36200
D4Ol8(e)
F32800
D4512(e)
F33100
Ferriticlpearlitic
D5506(e)
F33800
Ferritic/pearlitic
D7003(e)
F3-4800
Pearlitic
DQ&T(ei
F30000
Martensitic
ClassA
F33lOl
SAEJ434
SAEAMS5315C
0.08max
annealed
ASTM A 395; ASME SA395 ASTM A476; SAE AMs5316C A536
250max(b)
%
3.0max
0.08 max
0.05 max
As-cast
Ferritic: may be annealed Mostly ferritic; as-cast or annealed Ferriticlpearlitic: asc3st Mostly pearlitic: may be normalized
3.203.
IO
3.0 mm
1.80-3.00
2.50max(lI
0. IO-I .OO
0.015-O. IO 00050.035
0.08 max
Martensitic: oil quenched and tempered Ferritic
Ferritic:
annealed
General
uses
Pressure-containing parts for use at elevated temperatures Paper mill dryer rolls, at temperatures up to 230°C (4SO “F) Shock-resistant parts: lowtemperature service General service General service Best combination of strength and wear resistance and best response to surface hardening Highest strength and wear resistance hloderately stressed parts requiring good ductility and machinability Moderately stressed parts requiring moderate machinability Highly stressed parts requiring good toughness Highly stressed parts requiring very good wear resistance and good response to selective hardening Highly stressed parts requiring uniformity of microstructure and close control of properties Genera) shipboard service
Note: For mechanical properties and typical applications. see an adjoining table. (a) TC. total carbon, (b) The silicon limit may be increased by 0.08%. up to 2.75 Si. foreach 0.01% reduction in phosphorus content. (c) Carbon equivalent (CE). 3.84.5; CE = TC + 0.3 (Si + P). (d) Composition subordinate to mechanical properties: composition range for any element may be specified by agreement between supplier and purchaser. (e) General composition given under grade D4018 for reference only. Typically. foundries wilt produce to narrowerranges than those shown and will establish different median compositions for different grades. (f) For castings with sections I3 mm (r/z in.) and smaller, may have 2.75 Si max with 0.08 P max. or 3.00 Si max with 0.05 Pmax; for castings with section 50 mm (3 in.) and gteater, CE must not exceed 4.3
828 / Heat Treaters
Mechanical
Specitkation
Guide
Properties
and Typical
Grade or class
No.
Applications
Hardness, EWa)
for Standard
Grades of Ductile
Tensile strength, min(b) hlPa ksi
field strength, min(b) hiPa ksi
Iron Elongation in 50 mm (2 in.) (min), TO(b)
ASTMA39S;AShlESA395
60-40-18
l-13-187
111
60
276
40
I8
ASTM ASThl
80-60-03 60-W IX
201 min
552 41-l
80 60
41-I 176
60 10
3 I8
65-45-12
448
65
310
35
I2
80-55-06 loo-70-03
552 689
80 IO0
379 183
S5 70
6 3
8'7 .ll-t 448 55' -.689 (d) 11-l
I10 60 65 80 IO0 (d) 60
621 276 3I0 379 483 (d) 310
90 40 45 55 70 tdt -IS
2 I8 I2 6 3 k-9 15
A-t76tc);SAEAhISS316 AS36
IX-90-02 D4018 D-l512 D5506 D7003 DQ&T Class A
SAE J13-I
SAEAhlS53lSC
170m3x 156-217 187-155 ‘41-302 (CJ l90max
Qpical
applications
Valtesand fittings forsteamandchemicalplant equipment Paper mill dryerrolls Pressure-containing parts such as valw and pump bodies hlachine components subject to shock and f3tigue loads Crankshti, gezux. and rollers High-strenm gears and machine components Pinions, gem, rollers. and slides Steering knuckle5 Disk brake calipers Crankshaf& Gears Rocker arms Electric equipment engine blocks, pumps. housings. gears. valve bodies. clamps, and cl finders
Note: For composltions. descriptions. and uses see an adjoinmg table. la) hlcasurcd at a predetermined locanon on the casting tb] Dctermmed usmg a standard specimen taken from a separately cast test block, as set forth in the applicable specification (cr Range specified by murual agreement between producerand purchaser. (d) Value must becompatible with minimum hardness specified for production castings
Ductile Iron Property
Tensile strength MPa ksi
Grade Is0
Standard
800 70s 600 500 400 370 A 536 (United
60-40-18 6@42-IO 654% I? 70-50-05 80-55-06 80-60-03 loo-70-03 I20-90-02 SAE JC34 (United D4018 D-1512 DS506 D7OO3 DQ&T(c)
of Various
0.2 70 of&et yield strength hlPa ksi
National
and International Impact
Elongation (min) %
Standards energ
hfean(a) J
Indkidual ft. Ibf
J
ft
Ibf
Eardness,
EB
structure
1083 (International)
8002 loo-2 m-3 500-7 400-12 370-17 ASTM
Requirements
II6 I02 a7 73 58 54
480 420 370 320 150 230
70 61 51 46 36 33
2 ‘)
60 60 6.5 70 80 80 IO0 I70
276 290 310 345 379 111 483 621
10 42 4s 50 55 60 70 90
I8 IO I2
60 65 80 IO0 _..
276 310 379 483
10 1s 55 70
I8 I2 6 3
i 7 I2 I7
I3
9:s
;‘I
a.;
Z-18-352 229-302 197-269 I lO-Z-1 I
Pearlite or tempered Pearlite Pearlite + ferrite Ferrite + pearlite Ferrite Ferrite
I70 ma% 156.217 187-255 211-302
Ferrite Ferrite + pearl& Ferrite + pearlite Pearlite hlartensite
States)
41-l 41-I 448 485 552 552 690 877
z 3 3 2
States)(b) 411 448 552 690
(3) hlean value from three tests. (b) SpecilicaUons for these irons are pnmarilj based on hardness llnd auucture. and tempered Fade: hardness subject to agreement between supplier and purchaser
hleshunisal
properties
3re go\ en for infomation
only. (c)Quenched
Heat Treating
;E;e
Tentative
Grade
Specifications
Tensile strength (min) MPa kri
strength (min) hlPa ksi
3 103s 120.5 1380
Ductile
Elongation (min). %
and P/M Steels / 829
Proposed strength and elongation ranges of austempered ductile iron compared to established criteria for other grades of ductile iron. DE, Ductile Iron Society; BCIRA. British Cast Iron
0.2 % offset yield
Ductile Iron Society (United States) I 860 12.5 5.50 ; 4
for Austempered
Iron Casting
Research Association Hardness, HB
80
IO 7 -I 2
269-32 I 302-363 36.344 388-177
165 175 200
690 827 965
IO0 I’0 l-10
116 160 17-l
505 705 950
73 IO:! I38
a 5 2
x0-310 180-310 330-390
138 152 171
670 780 940
97 II3 I36
6 3
300-310 345-35s 39wOO
Sulzer (Switzerland) GCXXOBAF GGGIOO GGGllO
800 loo0 IX0
BClR4 (Great Britain) 95016 I oso/3 lxuvl
950 IOSO 1200
L
Microstructure. Fractograph showing the brittle fracture of a ductile iron dynamic tear specimen. 355x
830 / Heat Treaters
Guide
Seven graphite shapes used to classify cast irons
ASTM I.*peul I...
Equimknl IS0 formlb~ ,.,.,.......
VI
II
VI
Ill
IV
Description
Nodular tspherdall graphite Nodular (spheroidall graphite. imperfectly formed Aggregate. or temper carbon
4SThI I>pelP,
Equiralcnl IS0 lorml bl
IV.. _. _. V VI. VIIICI..........
ill ll \ I
Dewription
Quadlake graphwz Crab-form graphlte Irregular or open I)pe nodules Flake graphite
la) A\ delined m r\STM 4 3’. ~bl Ar &lined m ISOR 945 1969 IEI ICI D~\~ded mm fits wbt,pe$ umform ~lahc,. rowlr wperlmpuwd flake we. mterdendnuc. random onemauon. and mlsrdendm~c. preferred onenlalmn
groupmg:
Heat Treating
CC1 diagram showing annealing, normalizing,
Iron Casting
and P/M Steels / 831
and quenching. M,, martensite start; M,. martensite finish
lT diagram of a processing sequence for austempering: with the M, and M, decreasing as the y is enriched with carbon during stage I
832 / Heat Treaters
Guide
Microstructures. Optical micrographs of ductile iron with (a) a ferritic matrix in an annealed casting, (b) fine pearlitic matrix in a normalized casting, and (c) a martensitic matrix in a quenched casting. Etched in nital; approximate magnifications shown
Tensile strength vs elongation of ductile iron. (a) Minimum values given in various standards. (b) Minimum values of austempered tile iron grades specified in ASTM A 897. (c) Range of tensile strength and elongation values with different heat treatments
duc-
Heat Treating
Iron Casting
and P/M Steels / 833
Microstructures. Micrographs of ductile iron treated at different austempering temperatures. (a) Ductile iron austempered at 280 “C (500 “F) exhibits a fine acicular structure with the following properties: tensile strength, 1585 MPa (230 ksi); yield strength. 1380 MPa (200 ksi); elongation, 3%; unnotched impact, 54 J (40 ft. Ibf); hardness, 475 HB. (b) Same iron as in (a) austempered at 370 “C (700 “F) exhibits a coarse acicular structure with the following properties: tensile strength, 1035 MPa (150 ksi); yield strength, 825 MPa (120 ksi); elongation, 11%; unnotched impact, 130 J (95 ft. Ibf); hardness, 321 HB. Both etched with 3% nital. 300x. Source: Applied Process, Inc.
Elongation vs austempering time for a group of ductile iron alloys
834 / Heat Treaters
Guide
Influence of tempering temperature on mechanical properties of ductile iron quenched from 870 “C (1800 “F) and tempered 2 h. Data represent irons from four heats with composition rangesof:3.52to3.68%C,2.28to2.35%Si,0.02to0.04%P,0.22 to 0.41% Mn, 0.69 to 0.99% Ni, and 0.045 to 0.065% Mg. Data for tensile strength, tensile yield strength, and elongation are for irons (from two of these heats) that contained 0.91 and 0.99% Ni
Effect of austempering temperature on properties of ductile iron. (a) Yield strength and tensile strength vs austempering temperature. (b) Impact strength vs austempering
temperature
Heat Treating Chemical
Malleable
Irons
Composition
Compositions of malleable iron are found in accompanying tables. These irons are limited in two respects: their range of chemical composition and use of alloys. Chemical compositions usually conform to the following ranges: Composition,
%
Element
Ferritic
Peartitic
Total carbon Silicon Mallgall.ZSIZ SIllflU Phosphorus
2.2-2.9 0.9. I .9 0.2-0.6 0.02-0.2 0.02-0.2
2.0-2.9 0.9. I .9 0.2-1.3 o.os-0.2 0.02-0.2
Alloying elements. Small amounts of chromium (0.01 to 0.03%). boron (0.00’20%). copper (approximately I .O%), and molybdenum (0.35 to 0.5%) are sometimes present. Carbon Content. This element is not allowed to drop below a minimum value in the interest of mechanical quality and annealability. Reason: decreasing carbon content reduces the fluidity of molten iron and reduces annealability. Ln addition, maximum carbon content is limited because of the requirement that castings must be white as cast. Silicon content. Again, content is limited-in this instance, to ensure proper annealing during a short-cycle, high-production annealing process
Characteristics
of Malleable
and to avoid the formation of primary the solidification of white iron.
graphite
(known
as mottle) during
Manganese and sulfur contents. These elements are balanced to ensure that all sulfur is combined with manganese and that only a safe, minimum quantity of excess manganese is present in the iron. Any excess of sulfur or manganese retards annealing in the second stage, which adds to annealing costs. Chromium content. This value is kept low because of the carbide-stabilizing effect of this element and because it retards both fast stage and second stage annealing reactions. Motile is a mixture of gray iron and white iron, which produces a speckled appearance. The condition is particularly detrimental to the mechanical properties of annealed castings, both ferritic and pearlitic types. Control is obtained by maintaining a balance ofcarbon and silicon contents. How malleable is made. Both ferritic and pearlitic malleable irons are produced by annealing white iron of controlled composition. Annealing is an essential part of the manufacturing process. Different microstructures (ferritic, tempered pearlitic, and tempered martensitic. or bainitic) are produced by variations in heat treatment. The feature common to all malleable irons is the presence of uniformly dispersed and irregularly shaped graphite nodules in a given microstructure. The nodules. known as temper carbon. are formed by annealing white cast iron. This initial anneal is followed by additional heat treatments that produce specitic microstructures.
Iron
The matrix microstructure is the dominant factor influencing mechanical properties. Mechanical properties relate well to the hardness levels of different microstructures. The softer ferritic matrix provides maximum ductility with lower strength, while increasing pearlite content increases hardness and strength, but ductility is reduced. Martensite provides still higher hardness and strength, but with further declines in ductility. Mechanical properties of pearlitic and martensitic grades are clearly related to hardness. Properties of malleable iron castings, grades of malleable based on hardness, and grades specified on the basis of tensile properties are listed in accompanying tables. IXvo basic types of malleable are available: blackheart and whiteheart. The former is the only type produced in North America and is the most widely used gtade throughout the world Whiteheart is the older type, and is essentially decarbtuized white iron, produced in a long heat treating process. Malleable iron, like ductile iron, has considerable ductility and toughness because of its combination of nodular graphite and a low-carbon metallic matrix. Thus both malleable and ductile are suitable choices for some applications caUing for good ductility and toughness. In this instance. the deciding factors are economy and availability, rather than comparative properties. The advantage goes to ductile iron when sections are too thick to permit the solidification of white iron over 100% of the section. Another advantage of ductile iron, when low solidification shrinkage is needed.
Malleable
is preferred:
For thin section casting For parts that are to be pierced, coined, or cold formed For parts requiring maximum machinability For parts requiring good resistance to impact at low temperatures For parts requiring resistance to wear (applies only to martensitic malleable iron) Both malleable
and ductile
High resistance to corrosion ExceUent machinability Good magnetic permeability Low magnetic retention-for
iron provide:
magnetic clutches and brakes
Other desirable properties of malleable: good fatigue strength and damping capacity make this iron useful for highly stressed parts that see extended service. Other considerations. After heat treatment, ferritic or pearlitic castings are cleaned by shotblasting. Gates are removed by shearing or grinding, and. where necessary, castings are coined or punched. Close dimensional tolerances can be held with ferritic grades and the lower hardness types of pearlitic malleable, both of which are easily straightened in dies. The harder pearlitic irons are more difficult to press because of their higher yield strength and a greater tendency toward springback after die pressing. However, even the strongest pearlitic grades can be straightened.
838 / Heat Treaters
Heat
Guide
TLeating
Malleable
Irons
Like medium carbon steel, malleable can be heat treated to a bide varieb of mechanical properties. In addition to mill heat treating processes. pearlitic malleable can be selectively surface hardened with induction heating and quenching or flame heating and quenching to develop high hardness in heat-affected surfaces. Laser and electron beam processes have been used to get similar results. Malleable is also carburized, carbonitrided, and nitrided to add uear resistance to surfaces. Austempering has been used in specialized applications. Pearlitic malleable can also be hardened and tempered. martempered and tempered, and treated to produce hoth upper and lower bainite. The effect of tempering temperature and time on the hardness of ferritic and pearlitic irons is shown in an accompanying tahle.
Heat Treating Ferritic Malleable The microstructure of this iron is shown in an accompan> ing figure. A satisfactory structure consists of temper carbon m a matrx of ferrite. Annealing. A two-stage cycle IS required. The fust stage comerts primary carbides to temper carbon: the second converts carbon dissolved in austenite at the fust stage annealing temperature to temper carbon and ferrite. After First stage annealing, castings are cooled as rapidI> as practical to 710 to 760 “C ( I365 to I-KKI “F) in preparation for second stage annealing. Fast cooling requires I to 6 h. depending on the equipment. Castings are then cooled slowly at a rate of approximately 3 to IO “C tS to 20 “F) per h. During cooling. carbon in the austenile is converted to graphite and deposited on particles of temper carbon. The result is a full) fenitic matrix. Hardness can be considered an approslmate indicator that the ferritizing anneal was complete. Hardness of ferritic malleable almost aluays ranges born I IO to I56 HB. and is influenced b> total carbon and silicon contents.
Mechanical
properties
Also of interest are resistance solderahility. Other properties:
to corrosion.
weldability.
brazeability,
and
Tensile properties.
Llsuall~ measured on unmachined test bars. See table for tensile properties. Fatigue limit. That of unnotched specimens is about 50 to 60% of tensile strength. Notch radius generally has little effect on fatigue strength, but fatigue strength drops with increasing notch depth. Modulus of elasticity. This value m tension is approximately 170 GPa 125 x IO6 si). In comparison. the ranges are I SO to 170 GPa (22 x IO6 to 25 x IO 6 PSI): the value in torsion ranges from 65 to 75 GPa (9.5 x IO6 to I I x IO6 psi). Fracture toughness. Notch tests such as the Charpy V-notch are conducted over a range of temperatures to establish toughness behavior and the temperature range of transition from ductile to brittle fraction. Brittle fractures are most likely to occur at high strain rates, at low temperatures, and with high restraint on metal deformation. Elevated temperature properties. Short term, high temperature tensile properties typicall) show no sign of change to 370 “C (700 “F). Corrosion resistance. This propertq in ferritic malleahle is improved by the addition of copper (usually about I %,j in certam applicalions. Welding and brazing. Welding of ferritic iron almost always produces brittle white iron in the weld zone and the heat-affected zone immediately adjacent to the Held zone. In some cases. welding with a cast iron electrode ma) produce a brittle. gray iron weld zone. accompanying
Welding usuaUy is not recommended unless castings are subsequently annealed to convert carbide to temper carbon and ferrite. However, ferritic can be fusion nelded 10 steel u ithout a requirement for subsequem annealing if a completely decarburized zone as deep as the normal heat affected zone is produced at the faying surface of the malleable iron part before welding. Ferritic iron can be silver brazed and silver-tin soldered.
The most important properties for design purposes are tensile strength. yield strength, modulus of elasticity, faligue strength, tmpact strength. fatigue Loughness. and elevated temperature properties.
Heat
Treating
Pearlitic
and Martensitic
Both grades can be produced to a wide range of mechanical properties, depending on heat treatment. alloying, and melting practice. Lower strength pearlitics often are produced b> air cooling castings after the fist stage anneal; while the higher strength pearlitic/martensitic grades are made by liquid quenching after Ihe fiist stage anneal. With suitable heat treating facilities. air cooling or liquid quenching after the first stage anneal generallq is the most economical ual of making pearlitic or martenstticlpearlitic irons. The alternative is to reheat ferritic produced in two-stage annealing to the austenitic temperature. then quenching. Also. lower strength pearlitics can be made by alloying and a two-stage annealing process.
Heat Treatment
of Pearlitic
Malleable
The fiust stage anneal is the same as that for ferritic iron. After this. the process is different. Some foundries slow cool castings to approsimately 870 “C (I600 “F). During cooling, combined carbon is reduced to approximatelq 0.75%. Castings are then air cooled. Air cooling is accelerated b> an air blast to alold the formation of ferrite emelopes around temper
Malleable
Iron
carbon particles and to produce a tine pearlitic matrix. Castings are then tempered to specifications, or they are reheated to reaustenitize at approximat+ 870 “C (1600 “F), oil quenched. and tempered to specifications. Large foundries usually skip the reaustcnitizing step, and quench castings in oil dircctlq from the fust-stage annealing furnace after stabilizing the temperature at 845 to 870 jC ( I555 to I600 “F).
Heat Treating Pearlitic-Martensitic
Irons
These high strength grades usually are produced by liquid quenching and tempenng. The most economical procedure is to direct quench after first stage annealing. Castings are cooled in the furnace to the quenching temperature of 8-E to 870 “C ( IS.55 to I600 “F) and held I5 to 30 min to homogemze the matns. Castings are then quenched in agitated oil to develop a matrix mtcrostructure of martensite, having a hardness of 415 to 601 HB. Finally, castings are tempered at an appropriate temperature betkieen 590 to 725 jC ( IO95 to I335 jF) to develop specific mechanical properties. Rehardened and tempered malleable iron can also be produced from fully annealed ferritic iron \\ith a slight v,ariation in the heat treatment used for
Heat Treating
arrested-annealed (air quenched) malleable. The matrix of full) annealed ferritic is essentially carbon free. but the iron can be recarbunzed by heating at 840 to 870 “C (IS-15 to 1600 “F) for I h. Tempering times of 2 h or more after air cooling or liquid quenching are needed for uniformity. Control of final hardness is precise. Processing limitations are about the same as those for the heat treatment of medium or high carbon steels. especially when specifications call for hardnesses of 241 to 321 HB. Control limits of kO.2 mm Brinnel diameter can be mamtained with ease. Mechanical properties of pearlitic and martensitic iron vary in a suhstantially linear relationship with brittle hardness. In the ION hardness range. properties of air quenched and tempered pearlitic are essentially the same as those of oil quenched and tempered martensitic malleable iron. At high hardnesses. oil quenched and tempered malleable has a higher yield strength and more elongation than air quenched and tempered malleable iron. Oil quenched and tempered pearlitic is produced commercially to hardnesses as high as 321 HB. while the maximum hardness of high production. air quenched and tempered pearlitic malleable is approximately 255 HB. Tensile properties ofpearlitic normally are measured on machined test bars. Compressive strength is seldom detemrined. because failure in compression is rare. Shear and torsional strength. Shear strength of ferritic malleable is approximately 805, of tensile strength; for pearlitic. it ranges 70 to 9Oq of tensile. Ultimate torsional strength of ferritic malleable is approsimately 90c? of ultimate tensile strength. Yield strength in torsion is 75 to gOP( of ulttmnte tensile strength. Torsional strengths of pearlitic grades are ahout equal to or slightly less than the tensile strength of the material. Yield strengths in torsion vary from 70 to 75% of tensile yield strength. Modulus ofelasticity of pearlitic in tension is I76 to 193 GPa (25.5 x IO6 to 28.0 X IO” psi). Properties at elevated temperatures: generally room temperature tensile strengths are related to hardness. while tensiles above approxtmately 450 “C (840 “F) exhibit asymptottc behavior. Unnotched fatigue limits of tempered pearlitic malleable (air cooled or oil quenched) are approximately 30 to 50% of tensile strength. Tempered martensitic malleable irons (oil quenched) have an unnotched fatigue limit of approximately 35 to 45% of tensile strength. Wear resistance: hoth pearlitic and martrnsitic grades have excellent wear resistance.
Iron Casting
and P/M Steels / 837
Welding: both are difticult to weld hecause temperatures generated in the process can cause the formation of a brittle layer of graphite-free hhite iron. Ho\sever. both types of iron can be welded if the surface to welded has ken heavily decarburized. Brazing: malleable iron can be brazed u ith various commercial processes. Damping capacity: malleable irons perform well in long term service where parts are highly stressed. Reason: hecause of a combination of good damping capacity and fatigue strength.
Bainitic
Heat Treatment
of Pearlitic
Malleable
Both upper and lower bainite can he formed in pearlitic with a marked increase in tensile strength and hnrdness-but there is a loss in ductility. A pearlitic with a composition of 2.6 C. I.1 Si. 0.5 Mn. 0.11 S. for esample. was treated in this manner: it was annealed at 930 “C (1705 “F) for I6 h. air quenched. and tempered at 680 “C ( I255 “F) for 4 h. Properties developed uere: an ultimate tensile strength of 650 MPa (94.2 ksi). a yield strength of -I60 hlPn (66.5 ksi). and a 3.4% elongation at 900 T (,I650 “F). The same non austenitized at 900 “C (1650 “F) in molten salt for I h. quenched in molten salt at 295 “C 1565 “F) for 3 h. and air cooled developed an ultimate strength of 995 hlPa ( l-l-t.2 ksi) and an elongation of IQ at 388 HB. Selective Surface Hardening. Pearlitic is surface hardened by inductton heating and quenching. or by flame heating and quenching to develop high hardness in the heat affected area. In general, little difficulty is encountered in obtaining hardncsses in the range of 55 to 60 HRC. Depth of penetration is controlled by the rate of heating and surface temperature of the \vorkpicce hta~irnum hardness in the matrix of a properly hardened pearlitic casting is 67 HRC. Generally. a casting with this hardness has an average hardness of approximately 62 HRC. as measured by a standard Rockwell tester.
REFERENCES I. Article on malleable iron. Vol I. ASAI Handbook 2. L.R. Jenkins. Heat Treating of hlalleable Iron, Vol 4. ASM Hatldbook
838 / Heat Treaters
Guide
Microstructure. Structure of as-cast malleable white iron showing a mixture of pearlite and eutectic carbides. 400x
Properties
of Malleable
Microstructure. Structure of annealed showing temper carbon in ferrite. 100x
ferritic malleable
Iron Castings Classor
Specillcatioo No.
grsde
Tensile strength MPa ksi
Yield strength MPa k.si
Eardness, Et3
Ferritic ASTMA47andA338.ANSIG48.I. ASTM
FEDQQ-1-666~
32510 3SO18
3-u 365 276
SO 53 40
221 241 207
32 3s 30
lS6max lS6max 15611~
40010 -IS008 45006 soQos 60004 70003 80002 90001
414 418 4-l-18 483 552 586 655 724
60 65 65 70 80 85 9s 10s
276 310 310 3-1s 41-l -183 551 621
40 -IS 45 so 60 70 80 90
149-197 156-197 I%-207 179-229 197-24 I 217-269 24 I-285 269.32 I
34s 448 517 517 621 724
so 65 7s 7s 90 10s
22-l
32 35 so 55 70 85
156max 163-217 187-241 187-24 I 229-269 269-302
A 197
Pearlitic
and martensitic
ASTMA220.ANSIG488.2.
MlL-I-IIWB
Automotive ASTMA602.SAEJlS8
(a) Minimum
iron
in SO mm (2 in.). (b) Annealed.
M32lO(h) MWM(c) MSOO3k) MSS03td) M7002(dj MSSOl(d)
(c) Air quenched and tempered. (d) Liquid quenched and tempered
310 34s 379 483 586
Elongation(a), %
Heat Treating
Grades of Malleable SpeciBed
Grade
Iron Specified
hardness,
According
EB
to Hardness
Beat treatment Annealed
Ferritic
M 4503 M 5003
163-2 I7 187-241
Air quenched and tempered Air quenched and tempered
Ferrite and tempered pea&e(a) Ferrite and tempered pearlite(aj
M 5503 M 7002 M 8501
187-24 I 229-269 269-302
Liquid quenched and tempered Liquid quenched and tempered Liquid quenched and tempered
Tempered martensire Tempered martensile Tempered manensite
applications
For Ion-stress parts requiring good machinability: steering-gear housings, carriers. and mounting brackets Compressor crankshafts and hubs For selective hardening: planet carriers. transmission gears, and differential cases For machinability and improved response to induction hardening For high-snmgth parts: connecting rods and universal-joint yokes For high strength plus good wear resistance: certain gears
for some applications
Iron Specified
According
No.
to Minimum
grade(a)
ASIll metric equivalent class(b)
32510 35018
22010 24018
Class or Specification
l)pical
Microstructure
156max
Grades of Malleable
and P/M Steels / 839
per ASTM A 602 and SAE J158
M 3210
(a) May be all tempered martensite
Iron Casting
Tensile Properties Microstructure
l)pical
applications
Ferritic A47(c),
ASTM
A 338
(d)
Temper carbon and ferrite
ASTM
A 197, ANSI G49. I
(e)
Free of primary graphite
Pearlitic ASTM
ANSIG48.1.
FEDQQ-I-666c
Temper carbon and fenite
ASTM
General engineering service at normal and elevated temperatures for good machinability and excellent shock resistance Flanges, pipe finings. and valve parts for railroad, marine. and other heavy-duty service to 345 “C (650°F) pipe fittings and valve parts for pressure service
and marteositic A220(c),ANSlG48.2,
MU/l-
I I444B
JOOIO 45008 4sOO6 sxKn 60004 70003 8ooO2 90001
280MlO 3lOM8 3lOM6 34OMS 4lOM4 480M3 56OM2 620M I
Temper carbon in necessary matrix without primary cementite or graphite
General engineering service at normal and elevated temperatures. Dimensional tolerance range for castings is stipulated
(a) The 61% three digits of the grade designation indicate the minimum yield strength (xl00 psi). and the last two digits indicate minimum elongation designatedbyfootnote(c)provideametricequivalentclass wherethefustlhreedigitsindcateminimumyieldstrengthinMPa.(c)Specificationswilhasuffix”M”utilizethemetric equivalent class designation. (d) Zinc-coated malleable iron specified per ASTM A 47. (e) Cupola ferritic malleable won
(Q). (b) ASTM
specifications
Short-term elevated-temperature tensile strengths of (a) partially spheroidized pearlitic malleable irons produced by air cooling after the temper cation anneal, (b) finely spheroidized pearlitic malleable irons produced by oil quenching after the temper carbon anneal, and (c) oil-quenched and tempered martensitic malleable irons. The two martensitic malleable irons with hardnesses of 228 HB were reheated (reaustenitized) after the temper carbon anneal [18 h soak at 950 “C (1740 “F)] and then oil quenched. The 263 HB iron was oil quenched from 840 “C (1545 “F) after an anneal of 9.5 h at 950 “C (1740 “F). After oil quenching, all three martensitic irons were tempered
840 / Heat Treaters
Microstructures.
Guide
Structure of air-cooled peatiitic malleable
iron. (a) Slowly air cooled. 400x. (b) Cooled in an air blast. 400x
Hardness vs depth for surface-hardened pearlitic malleable irons. Curves labeled “Matrix” show hardness of the matrix, converted from microhardness tests. 0, oil quenched and tempered to 207 HB before surface hardening; A, air cooled and tempered to 207 HB before surface hardening
Heat Treating
Microstructures. Structure of oil-quenched (d) 229 HB. 500x
Iron Casting
and P/M Steels
/ 841
and tempered martensitic malleable iron. (a) 163 HB. 500x. (b) 179 HB. 500x. (c) 207 HB. 500x
842 / Heat Treaters
Guide
Effects of austenitizing temperature and quenching medium on hardness of as-quenched malleable iron. The listed composition limits for ferritic and peatiitic malleable iron are general limits given in the iron Castings Handbook 1981. In practice, manganese content is 0.2 to 0.45% Mn for the ferritic class and less than 0.6% Mn for the pearlitic class
Influence of time and tempering temperature on room-temperature C, 1.45to 1.55%Si,0.03%P,0.06to0.15%S,0.38to0.50%Mn,andlessthan0.003%Cr
hardness of pearlitic malleable iron. Composition:
2.35 to 2.45%
Heat Treating
Iron Casting
and P/M Steels / 843
Effect of tempering temperature and time on the hardness of ferritic and pearlitic malleable irons in the as-received and reheatedand-quenched conditions
compmltka. Iron
I 2
M&&l
Standard (ferritic) grade 32510 Pearlitic malleable iron. grade 45007
iron.
%
Hadme=.
Atbying and prior haI treabnenf
HI
0.30
Unalloyed;
fully malleablized
I16
0.072
0.30
156
1.80
0.072
0.30
2.40
I.80
0.072
0.30
Unalloyed: air quenched from 925 ‘C (I 700 ‘F). tempered 8 h at 695 “C (1280°F) Unalloyed; oil quenched from 870 T (1600 “F). tempered 3 h at 650 T (1200 “F) Unalloyed; oil quenched from 870 “C (1600 “F). not tempered Alloyed (Mn): air quenched from 940 “C ( I720 “F). tempered 34 h at 715 “C (I320 “F) Alloyed (Mn and MO); air quenched from 940 “C (I720 “F), tempered I2 h at 620 “C (I I50 “F) Alloyed (Mn): air quenched from 925 T f 1700 “F). not tempered Alloyed (Mn); air quenched from 925 “C (I700 ‘F). not tempered Alloyed (Mn); oil quenched from 830 “C (I525 “F). not tempered Alloyed (Mn): oil quenched from 830 “C (I525 “FL not tempered Alloyed (Mn and MO); air quenched from 940 “C (I720 “F), nor tempered
TC
SI
S
Ma
2.40
1.80
0.072
2.40
1.80
2.40
3
Pearlitic malleable grade 60003
4
Oilquenched iron
5
Pearlitic malleable grade 450 IO
iron.
2.40
I.80
0.076
0.90
6
Pearlitic malleable grade 80002
iron.
2.40
1.80
0.072
0.90
7
Air-quenched alloyed malleable Iron
2.40
I.80
0.079
0.90
8
Air-quenched alloyed malleable iron
2.40
1.80
0.076
I.10
9
Oilquenched alloyed malleable iron
2.40
1.80
0.079
0.90
IO
Oilquenched alloyed malleable iron
2.40
I.80
0.076
I.10
II
Air-quenched alloyed malleable iron
2.40
1.80
0.072
0.90
malleable
MO
0.45
0.45
212
444
192
262
285
321
514
578
514
Heat Treating Chemical
P/M Tool Steels
Compositions
Commercial compositions of high speed 1001 steels. cold work die steels. and hot work die steels are presented in an accompanying table.
Characteristics Povvder metallurgy versions of high speed steel tools have significantly beuer toughness and grindability than their conventionally produced counterpts. Highly resulfurized grades offer improved machinability. Other grades difficult to produce convemionally are readily made Lviith the P/M process.
Heat Treating
P/M Tool Steels
Proper heat uealment of tool steels is essential for developing their properties. This is especially true of high-speed and high-alloy materials. Improper heat treatment of these sleels can result in a tool with greatly reduced properties or even one that is unusable. Ponder mernllurgy tool steels utilize the same basic heat treatments as their conventional counterparts. but they tend to respond more rapidly and with better predictability IO heat treatment because of their more unifomr nucrosu-ucture and finer carbide size. The basic heat treatments used include preheating, austenitizing. quenching, and tempering. Honever. optimum heal-treating temperatures may vary somewhat. even if chermcal compositions are identical. The following procedures are specific to ASP high-speed tool steels. bur are generally applicable LOall P/h4 high-speed tool steels. Deviations from these practices may be needed for some specific alloys and applications; in such cases, the recommendations by the manufacturer should he followed. The basic heat ueatment steps are: l
l
l
l
Heat to 850 to 900 “C ( IS60 IO 1650 “F). Slow cool to 700 “C (1290 “F) 31 IO “C (30 “F) per h. Typical annealed hardness values for ASP 33 are approximately 26 HRC max. 33 HRC for ASP 30. and 36 HRC for ASP 60 Stress relielittg (before hardtwitrg): Hold for approximately 3 h at 600 IO 700 “C (I I IO to 1290 “Fj. Slow cool to 500 “C (930 “F) in furnace Hardening: Preheat in IUO steps. fusl at 150 to 500 “C (840 to 930 “F) and then at 850 to 900 “C (IS60 to 1650 “FL Austenitize at 1050 IO II 80 “C (1930 10 ?I55 “F) and quench, preferahly in neutral sah baths. Cool to hand warmth 7ktnpering: Raise temperature to 560 “C ( 1040 “F) or higher. Repeat IWO or three times for at least I h at full temperature. Cool to room temperature between tempers
Annealing:
Sull other grades (superhigh speed steels such as CPM Rex 2Oj are available only as P/M grades. A distinguishing feature of PA1 tool steels IS the uniform distribution and small size of primary carbides. The same is uur of sulfide inclusions in resulfurized grades. hlicrostructures of P/M and conventionally produced high speed steel are compared in an accompanying figure.
The hardnesses of three Plhl high-speed tool steels after hardening and tempering are shot+ n in an adjoining Figure. Three types of distortion are experienced metallurgically during heat treatment: l l
l
Normal volume change due to phase transfomrations in the steel Variations in volume change in different parts of the tool due to the segregation in the steel Distortion due to residual stress caused hy machining or nonuniform heatmg and cooling durmg heal ueatment
Powder metallurgy grades. hovtcver. differ significantly from conventionally manufactured high-speed tool steels. Dimensional changes are more uniform in all directions. Because P/h1 high-speed tool steels are scgregauon free. variations in dimenslonal change are smaller. Therefore, Ihe dimensional change that occurs during hardening can be predicted more accurately. Conventionally processed high-speed tool steels go out-ofround in a four-cornered pattern. The extent of dislortion during heat treatment depends on the type and degree of segregalion. In P/M highspeed tool steels. anisotropy is smaller. and out-of-roundness occurs in a close. circular pattern.
REFERENCE I. K.E. Pinnou.
IV. Stusko. Phi
Tool Steels. Vol I. r\SM Handbook
Heat Treating
Commercial Trade
Iron Casting
and P/M Steels / 845
P/M Tool Steel Compositions AW designation
name
Constituent C
Cr
1.28 1.28 2.30 1.00 1.30 I .3s I .SS I .OO I.10 1.30 I.30 1.30 1.80 I .ss l.SS I.50 I.50 I.35 I .30 I.SO 1.00 2.00 0.95
4.20 4.20 -t.w -I. I s 1.00 l.3 -1.15 4.15 3.7s -lm -1.00 3.7s -1.00 -1.00 4.00 3.7s 3.7s 5.0 1.0 -1.0 -1.0 4.0 4.0
H
elements,
hlo
\
5.00 500 7.00 5.00 SO0 1.50 4.50 S.00 9 so 5.00 5.00 IO.SO 6 SO
5.3 5 ‘5 6.0 5.0 6.0 4.0 IO.0 6.0
3.10 3.10 6.SO 200 3.00 J.00 -I.00 2.00 1.1s 3.00 3.00 2.00 5.00 5.00 s.00 1.10 3 IO 3.8 3.0 1.0 70 -l.S 3.5
1.30 1.30 0.50 I so
9.00 9.7s 5 7s 1.00
I .3O 0.40 0.40
I .Oj 2.10 1.00
%
Eardoess,
co
s
Other
EIRC
High-speed tool steels(a) ASP23 ASP30 ASP60 CPhl Rex MlHCHS CPhl Rex M3HCHS CPhl Rex hl4 CPM Rex M-IHS CPhl Rex h13SHCHS CPhl Rex hl-12 CPM Rex 1.5 CPhl Rex 4SHS CPhl Rex 20 CPM Rek 25 CPhl RexTlS CPhl ReaTlSHS CPhl Rex 76 CPM Rex 76HS HAP IO HAP40 HAPS0 HAP60 HAP70 KHA 33N Cold-work
h13
hl’ 1113 h1-l hl4 h13S hll2
M62 h16 I TIS TIS 11148 hl-18
CPhl I OV CPhl4-W’ vmaclis -l Hot-work
65-67 66-68 67-69 fs4-66 65-67 6-l-66 64-66 65-67 66-68 66-68 66-68 66-68 67-69 65-67 65-67 67-69 67-69 6-t-66
8.5 IO.50
s.0 8.0 8.3 8 2S
so 5.0 9.00 9.00
0.27 0.17 0.06 0.22 0.27 ai3 0.22
0.06 0.22 0.06 0.2’
8.0 8.0 12.0 12.0 0.6ON
65-66
tool steels
CPhl9V
CPhlHI3 CPhl HI9 CPhl H19V
6.10 6.40 6.50 6.10 6.25 5 7s 5.75 6.00 I SO 6.25 6.25 6 25 1250 12.25 12.15 100 IO 0 3.0 6.0 X.0 10.0 12.0 6.0
All
I.78 2.45 2.15 150
5.25 5.25 17.90 8.00
0-m 0.40 0.80
5.00 4.3 4.25
0.03 0.07
53-5s 60-62 57.59 59-63
tool steels HI3 HI9
4.25 1.25
4.2s 4 2s
12-48 W-52 44.56
(a) HCHS. high carbon. high sulfur: HS. high wlfur
Microstructures. Microstructures of high-speed tool steels. Left: CPM T15. Right: Conventional T15. Carbide segregation and its detrimental effects are eliminated with the CPM process, regardless of the size of the products. Source: Crucible Materials Corporation
848 / Heat Treaters
Austenitizing
Temperatures
58 60 62 6-l 66
of ASP 23 Steel
Temperature
Eardness, ~Cb)
Guide
T
loo0 1050 1100 II40
1180
OF 1830 I925 2010 2085 2155
Salt bath(b) min/mm min/ii.
0.59 017 0.39 0.31 0.24
15 13 IO 8 6
Hardness of ASP steels after hardening and tempering a 25 mm (1 in.) diam specimen three times for 1 h. (a) ASP 23. (b)
Other furnace, min(c)
ASP 30. (c) ASP 60, cooled in salt bath. Hardening temperatures for the curves are: A, 1180 “C (2155 “F); 6,115O “C (2100 OF); C, 1100”C(2010”F);D,1050”C(1920”F)
30 25 20 IS IO
(a) After triple temper at 560 “C ( 1040 “F): hardness values may vary by f I ?I. (b) Total immersion time after preheating. (c) Holding time in minutes after tool has reached ti~ll temperature
Out-of-roundness measurements on test disks after hardening and tempering. Test disks machined from 102 mm (4 in.) diam bars. (a) AISI M2. (b) ASP 30
L
Heat Treating
Relative wear resistance, red (hot) hardness, and toughness of CPM and conventional terials Corporation
Iron Casting
high-speed
and P/M Steels / 847
tool steels. Source: Crucible Ma-
Heat Treating Chemical
P/M Stainless
Compositions
Properties and compositions of compacting ders are shown in a accompanymg table.
Characteristics
grade. stainless steel PO\+-
of P/M Stainless
Compositions are held to tighter tolerances than those for AlSl grade wrought stainless steels. Low carbon and high nickel content in austenitic grades of powder contribute to good compressibility. Austenitics are the most widely used grades. accounting for about one-third of total usage. Alloyed powders are characterized b) their irregular shape (see Figure). In comparison with low alloy. ferrous powders, stainless steel powders require higher compacting pressures in par&making, and their strength before sintering (green strength) is lower-about half that of P/M iron.
Sintering
of Stainless
Process
Green compacts usually are presintered in air or nitrogen at 425 to 540 “C (7% to 1000 “F) to volatilize and bum off pressing lubricant. If temperatures are higher. a protective atmosphere is required. Lubricant must be removed. because it can cause carburization of the alloy in sintering; carburization reduces the machinability and corrosion resistance of austenitic alloys. Martensitic alloys that contain carbon must be presintered in rutrogen.
Sintering
In commercial practice. compacting pressures range from 550 to 830 MPa (-10 to 60 tsi). Lubricants used In compactmg powders. such as steak acid, Increase green strength to some extent. and generally lower the compactability of powders. Powders are formed into parts (also called preforms at this stage) in dies. Carbide dies are used because highI> alloyed powders are inherently harder than pure metals such as iron or copper.
Powders
This is the most critical step in processing. Dunng smtenng, lubricants must be removed from parts and powder particles must be bonded together. to give parts the density and associated mechanical properties required in a given application. Average sintering temperatures range from I I20 to I IS0 “C (2050 to 2 100 “F). Temperatures are increased up to I3 IS “C (2100 “F) and higher when improvements m mechanical properties and corrosion resistance are needed. Equipment: up to operating temperatures of approximately I IS0 “C (2100 “F) continuous. mesh belt furnaces do the job. At higher temperatures, manual. automatic pusher, walking beam, or vacuum furnaces are used. Atmospheres used are dissociated ammonia, nitrogen-based atmospheres. and hydrogen. Vacuum furnaces are an alternative
Sintering
Steel
atmospheres
Dissociated ammonia is the most N idely used. A dew point of -IS to -SO “C (-SO to -60 “F) is required to prevent oxidation. However, dissociated ammonia is getting competition from nitrogenbased atmospheres that contain as little as 34 hydrogen. because of the rising price of dissociated ammonia. which contains 7ScC hydrogen. Hydrogen is seldom used commercially because of its high cost.
Use of vacuum is the principal alternative to both dissociated ammonia and mtrogen-based atmospheres. The process is described as partial pressure smtering. Conventional. cold wall vacuum furnaces are used. In vacuum furnace practice. chromium evaporates if furnace pressure falls below the elemental Lapor pressure. and resistance to corrosion is sipnificantlj reduced. Chromium content can be virtually depleted in a typical vacuum sinterinp cycle if the \ncuum lets1 is not properly controlled. Control is provided by backfilling the furnace with a sultable gas to a partial pressure abo\ e the vapor pressure of any of the elements in the alloy. A gas pressure of 27 to 67 Pa (200 to SO0 Hg) is t) pical for sintering at I3 IS “C (‘-100 “F). With argon as the backtill gas. mechanical properties are similar to those obtained ithen hydrogen IS used. With nitrogen. sintered properties are similar to those obtained with dissociated ammoma.
Sintering
Cycles
Tensile strength increases n ith sintering temperature and time. but yield strength drops. After surface oxides are reduced in the initial stage of sintering. powder particles bond together by solid state diffusion. A high degree of dimensional change (shrinkage) takes place when sintering IS at higher temperatures. especially in hydrogen. Longersintering times increase all tensile properties and shrinkage as well. Cooling Rates. Reg‘ardless of the sintenng atmosphere, cooling rate has a profound effect on the properties of sintered austenitic stainless. TypIcall) used rates of cooling pro\ ide the best combination of strength and ductility; and N hen dissociated ammonia is used, nitrogen is also present. N’ith extremely slow cooling precipitation occurs preferentially at grain boundaries. The result is a noticeable increase in strength and loss in ductility. even when precipitation is minimal.
Heat Treating
Carbide precipitation is detrimental to machinability. Precipitation at grain boundaries is reduced when cooling rates are normal. The result here is lower strength but higher ductility. Rapid cooling, i.e.. water quenching. suppresses the precipitation of carbides and nitrides, which produces maximum ductility. The cooling rate effect in vacuum sintering is largely controlled by the atmosphere in uhich parts are cooled. With a nitrogenbackfill, properties are similar to those obtained bv sinterine in dissociated ammonia. With argon. properties are similar to those obtained with hjdropen. ,
Iron Casting
Control of Carbon Content. Austenitic than 0.03%, carbon. Maintaining this level carbon pickup. ensures maximum corrosion machinability.
and P/M Steels / 849
grades are made with less after sintering. meaning no resistance. weldability. and
REFERENCE
LI
Effect of Sintering Temperature of Tensile and Yield Strengths g/cm3 and sintered for 30 min in various atmospheres
Effect of Sintering Temperature on Elongation and Dimensional 6.85 g/cm3 and sintered for 30 min in various atmospheres
I. R.W. Stevenson,
and Apparent
Change
Hardness
Plhl Stainless Steel. Vol 7. ASM Handbook
of Type 316L Stainless
During Sintering
Steel. Pressed to 6.85
of Type 316L Stainless
Steel. Pressed to
850 / Heat Treaters
Guide
Influence of Sintering Atmosphere on Mechanical Properties of Type 316L Pressed to 6.85 g/cm3
Microstructure.
Scanning electron micrograph of water-atomized type 304L stainless steel (-100 mesh). Magnification: 150x
Property Llltimarr tensile suengm, MPa (psi) Yield strength. hlPa (psi) Elongation in 25 mm r I in.). 5 Apparent hardness, HRB Note: Compacts
Compositions
and Properties 303L(a)
Chemical analysis, 5% ChKlmiUlll Nickel Molybdenum MaIlgalMX Silicon Carbon Iron
17.5 12.5 0.2 0.7 0.02 rem
of Stainless
Steel Compacting-Grade 304L
18.5 Il..5 0.3 0.8 0.02 rem
316L
Sintered in dissociated ammonia
Sitered in hydrogen
365.-l (53 000) 271.1(39 800) 7.0 67
288.2 (1 I 8001 I83 -I (26 600) IO.9 47
sinrered for 30 min at I I30 “C (2050 “F)
Powders 8mw
4lOL
434L
I65 13.5 2.1 0.2 0.7 0.02 (maxi rem
20.5 30.0 2.5 0.2 I.0 0.02 rem
12.0
17.0
0.5 0.8 0.0’ rem
I.0 0.2 0.8 0.02 rem
Physical properties Apparent density, g/cm3 flow rate. s/50 g Screen analysis,
3.1 ‘6
2.7 30
2.7 30
2.8 30
2.9 28
2.8 29
I 7 I3 24 55
I 12 20 25 42
I II 18 26 44
I Y I-l 27 39
I l-l 20 26 39
I II I7 27 4-l
9%
+lOOmesh -lOO+ 150mesh -lSO+ 200mesh -200 + 32.5 mesh -325 mesh
Note: Type 830 is used for the manufacture of P/M parts where superior corrosion resistance is of primary consideration. Parts made from type 830 rxhihit improved resistance to oxidizing media and sulfuric acid. This grade is not recommended forcondidons involving unstable chlorides. (a) 0.2% sulfur added for machinability. (b) 3.5% copper also present
Compactibility
of Stainless Steel Powders. (a) Type 316L austenitic stainless steel. (b) Type 41 OL martensitic stainless steel
Heat Treating
Tensile Properties of Standard Type 316L Stainless Steel Metal Powder Industries Federation Tensile Bars. Bars sintered in vacuum for 2 h using argon and nitrogen as backfilling gases. A partial pressure of 400 pm mercury was used to prevent vaporization of chromium
Properties
of Sintered
Type 41 OL Stainless
Processingtreatment As sintered and cooled in water-jacketed zone of furnace
Reheated in dissociated ammonia and oil quenched from 950 “C ( 1750 OF)
Reheated in hydrogen and oil quenched from 950 “C ( I750 OF)
(a) Sintered for 30 min at I 120 “C (2050 “F)
Graphite added, 90 8.10 0 0 10 0 0.10 o”.lO 0 0.10 8.10
Iron Casting
and P/M Steels / 851
Dimensional Changes for Qpe 304L Stainless Steel. Dimensional changes were determined on transverse-rupture bars sintered for 45 min in -40 “C (-40 “F) dew point dissociated ammonia and were calculated from die size
Steel Sinteriug atmosphere(a) Dissociated Dissociated Hydrogen Hydrogen Dissociated Dissociated Hydrogen Hydrogen Dissociated Dissociated Hydrogen Hydrogen
ammonia ammonia
ammonia ammonta
ammonia ammonia
Tempering temperature OC
Tensile strength OF
205
400
175 205 2’0 220
350 4xJ 130 430
105 205 2’0 205
2 -I30 -loo
Apparent bardnas, BRB
MPa
ksi
724 683 393 710 627 703 717 752
105 ZT 103 91 102 I04 I09
102 103 68 95 I06 I02 105 I06
731 745 641 800
106 108 II6 93
I04 104 101 95
Heat Treating Chemical
of P/M Steel
compositions
Tables accompanying this text provide compositions and applications of a variety of ferrous P/M materials, typical mechanical properties. and other
Characteristics
practical infomratron such as the green denshy of different and typical mechanical properties of forged P/M alloys.
Depth of hardening depends largely on porosity and alloy content. The latter must be determined precisely, because of its effect on the heat treatmg process. Additions of chromium and molybdenum. for instance. increase hardenability Response to hardening also depends on combined carbon content, not necessarily total carbon, and the amount of carbon that dissolves in the austenite. Sintering time and temperature are also importanr. If too little combined carbon (excessive graphite) IS present. the condition can be compensated for by using higher austenitizinp temperatures to dissobe most or all of the graphite. .4 caveal: loo much cementite can be formed. making parts excessively brittle after heat treatment Problems are encountered in testing for hardness because of the presence of porosity and free graphite. Indemation readings indicate loher than
Recommended
Heat
Treating
actual hardness \aIues. One reason is that free graphite does not indicate hardness u hen measured by the indentation method. Porosity is the primary cause of error. As porosity is reduced. differences between indicated and actual hardness become smaller.
Process
Combined C %
Temperature “C
OF
915 900 885 870 860
I680 I6.50 I63 I tm 1580
Recommended l l
l
practice is to:
Evaluate hardness of heat treated samples with microhardness testing Follou up with a suitable indentation method. such as Rockwell A. to establish an acceptable range of ohserved hardness After doing the ahovc. comentional hardness wsCng may be used as a quality control mol. hm continued monitoring with microhardness tesling is advised
Forging
P/M Steel Parts
Properties are upgraded significantly by reducing porosity u ith forging and repressmp processes. Both are discussed later in this article.
Practices
Generally. PIM compacts are less homogeneous than their rolled or forged counterparts. To get complete ausrenitization. higher temperatures or longer times at temperature are requtred. The follow inp nus~enniring temperatures are recommended:
0.15 0.35 0.15 0.55 0.65
iron powders
of P/M Parts
With some exceptions these materials are treated in much the same manner as theircast or forged counterparts. Exceptions stem primarily from the inherent porosity of P/M parts. Esamples Include:
Austenitizing
Parts
Ties usually run abotn 505% longer than those for treating wrought parts. When alloying elements are present. both temperature and time are slightly higher. A variety of batch and continuous type furnaces are used in austenitizing. Austenitizing atmospheres. In through hardening. parts nomrally are heated in a gaseous amrosphere. such as that provided hy an endothermic generator. Any nitrogen-based atmosphere may he used, as long as its carbon potential is controlled to match the carbon content of the workpiece.
V’acuum atmospheres are also used. Heating in molten sall is not recommended. even when parts have maximum densit\. Parts are difficult to wash after heating in molten salt. and any salts left-in pores cause m~msdia~s corrosion. Quenching austenitized parts. Parts have a greater tendency toward cracking than rhsir wrought counlerparts. Aqueous quenchants are used. but oil is preferred because it provides a less drastic quench. FM oils expedite quenching IO maximum hardness. Aqueous quenchants (uater and brine. waler and caustic, plain water. and polymer quenchants) are used to obtain full hardness in quenching plain carbon steel parts u ith secnons greater than approximately 5 mm (0.2 in.). In using these quenchants. however. parts can crack. and aqueous media can cause corrosion. Parts u ith thicker sections should contain sufficienl amounts of alloying elsmerns. such as nickel. manganese. and/or chrommm.
Tempering
P/M Parts
All austenitired and quenched parts should be tempered immediately after quenching. In tempering. forced air. convection-type furnaces are preferred. Use of sah or molten metal is not recommended. Tempering remperaurres should be at least IS0 “C (300 “F). Higher temperatures may he used. hut loss of some hardness is a tradeoff.
Heat Treating Iron Casting and P/M Steels / 853
Steam Treating Process This process is frequentlq used in conJunctIon wllh Iempering aS a protective atmosphere at temperatures up to approximately S-10 “C ( 1000 “F). Serendipitous henefits are hqproducts: an oxide coating (usually hluish) is developed on surfaces. u hich serves as a finish that improves resistance to wear and corrosion. and improves appearance as bell. Still another benefit is realized: in Ihe treatment. ferrous-ferritic oxide forms in pores and tends to close them. Entrq of contaminants into pores IS minimized or eliminated. and resistance to hydraulic pressures is improved. Little adjuncl equipment is needed to convert a forced air. rempering furnace for steam trealing. Recommended
processing
sequence
for steam treating:
Load depeased parts in a cold or nearly cold furnace in haskels, making sure parts are separated After closing furnace. set it at 370 “C (700 “F) lnlroduce steam at full pressure H hen furnace temperature rcache$ 345 “C (655 “F) Purge furnace chamber u ith steam for IS mm when temperature reaches 370 “C (700 “F) Adjust and maintain furnace pressure at a slightly positive pressure for an additional IS min Heat load to 510 “C ( IO00 “F) and hold I .S h u ith steam on Cool charge to 290 “C (555 “F) Remove parts from furnace after steam IS turned off When parts cool to 390 “C (555 “F) they can be quenched in mineral 011 to improve appearance and resistance to corrosion
Typically. the process. in comparison wilh gas carburizing. is carried out at a lower temperature, i.e., 55 “C (I 30 “F) lower and a shorter time. i.e.. a half hour or more. Nitrogen diffuses into steel surfaces simultaneously with the carbon. Applications. Carhonitriding is widely used in case hardening parts made of ferrous pobders. Sintered densities vary from approximately 6.5 g/cm’ up to approximately 7.9 g/cm3. Parts may be intiltrated with copper prior to carhonilriding. The process is exvemely effective in case hardening and is reasonably effective in ueating parts with 10 densities of 7.3. ,@m3. loner densities. Equipment. Batch-type. shaker hearth, and belt-type continuous fumacss are well-suited to the process.
Process. The processing, cycle, including gas composition, is critical. Ammonia conlent, usually 10%. increases hardenability and affects dimensional stability. often a critical economic consideration in evaluating the feasibility of making parts with Ihe P/M process. Of equal importance are control of temperature and Ihe quenching medium selected. Tempering. Generally. temperatures are higher than those used in tempering similar urought parts. If temperatures above 205 “C (300 “F) are required. parts should he cleaned u ith ultrasonic degreasing. Porescontaining oil can pose a fue hazard. hut at temperatures normally used, oil is removed in the tempering process. Hardness testing. Because cases are very thin. hardness can? he determined \+ith common indenlation methods. File tesling is the primary method for routine evaluation. hlicrohardness is used to detemline actual hardness.
Case Hardening
Nitrocarburizing
A clear case-core relationship can he ohtained only k%hen parts have a density of at least 7.2 g/cm3. VanOUS case hardening methods are used. but success with a given process tends 10 depend on the application. Processes discussed here are gas and pack carhurizmg. carboninidinp. nitrocarhurizing. and gas nitriding.
Salt bath and gaseous fenitic processes are abailable. The former, however. 1s not well suited to the P/M process. The gaseous process is a nitrogen and carbon system. like the carbonitriding process. The difference is that in gaseous nitrocarburizing, temperatures are completely within the ferrilic phase field. Carbonitriding is in the austenitic range. The temperature in nitrocarburizing is typically approxlmately 570 “C ( IO60 “F), which is slightly under thal for carhonitriding. The pnmaq ohjectlre In gaseous nitrocarhurizing is to produce a thin layer of iron carhonitride and nitrides (the white layer, or compound zone), and an under11 ing diffusion zone containing dissolved nitrogen and iron (or allo).) ninides. White layer provides resistance to galling. corrosion, and wear. The diffusion zone significantI> Improves faligue properties of carbon and low alloy P/hi parts. Process. Typically. sealed quench batch furnaces are used. and are of the same design as those for gas carburizing and carhonitriding. Furnace operating temperatures are low enough to maintain workpieces in the ferritic condition. .L\lmosphere composition can vary with the process. For example. in one process equal amounls of ammonia and endothermic gas are used, while in another. the atmosphere conslsls of 3SF ammonia and 65% refined exothcrmlc pas (+&A Type 301). which is nominally 97% nitrogen. and may he enriched b? a hydrocarbon gas such as methane or propane. Time cycles usually range from I to S h. hut cycles of no more than I h usuallv are recommended because deep penetration (into pores) can cause exc&ive embritdzment. Quenching. Optimum rcsuhs are ohlained with oil quenching from the plDCt?SSing temperature. Final word: because cases are extreme11 thin, usage of the process should he confined to fmished parts. No stock is removed after nitrocarburizing.
Carburizing Parts with combined carbon conlent around 0.10 10 0.20% and free of graphite can he carburized by the conventional gas or pack methods. Liquid carhrri:irrg is not recommended-it is difficult to remove salt from pores by washing. Pack c-urhtri:irlg is not economical in large volume production of small parts. and the method is seldom used. Gas rurbrrri:irrg is the more practical. though seldom used. process. Part density and composition are the importan considerations. Porosity in low density parts poses a prohlem: carhurizing gases penetrate pores. and it is nor possible LOget a distinct case. Carbon pene[ration may he so deep that thin sections of parts may be brittle. In addition. conventional gas carhurizinp does not increase hardenahility. meaning that plain carbon steels must he quenched in an aqueous medium. and cracking is possible. especially if carbon penetration is excessive. C~sr deph depends on rime and temperature. Results thal can he expetted with high densin pans are comparable to those in carburizing wrought parts.
Carbonitriding
Process
This process does not present the diffusion problem In carburizing thal is associated with porosity. In carhonitriding at 790 to 815 “C I 1-M 10 1555 . . “F) the problem is avoided. Lower rates ot dlttuslon allow closer control of case depth and adequate buildup of carbon in rhe case. File hard cases with a microhardness equal to 60 HRC and a predominately martensitic structure are consistendy oblained. Typical case depths range from 0.08 10 0.30 mm (0.003 10 0. I? in.). Case depths of copper-infilrrated parts approach those of wrought parts.
Process
Gas Nitriding Applications
of this process are extremely
limiled
for several reasons:
854 / Heat Treaters Guide
Repressing
As in gas carburizing, cycles are long and nitriding gas penetrates deeply into pores. The condition is difficult to control, and often results in excessive embrittlement l Carbon content should be maintained within 0.30 to 0.508 l Alloying elements that form hard, stable nitrides must be present. Both chromium and aluminum promote nitride formation Process. For optimum results, treatment should be initiated by austenitizing. quenching, and tempering parts. Success requires a microstructure of tempered martensite. Next, parts must be finished or thoroughly cleaned to produce the surface required for nitriding. l
Annealing
Repressing l l l
Parts
at room temperature
has a number of advantages:
Density and hardness are increased Mechanical and physical properties are improved Parts are held close to final dimensions-the amount of material deformation is greater than that possible with sizing because forces are greater
Forging
Process
Sintered
P/M Parts
Unsintered, presintered. and sintered parts are forged (or hot formed). The concept: a porous prefoml is densitied by hot forging with a single blow in a heated. totally enclosed die. Virtually no flash is produced. Sintered preforms can be forged directly from the sintering furnace: or stabilized at lower temperatures and forged; or cooled to room temperature. reheated. and forged. Heat treating practices are the same as those for conventionally processed materials similar in composition. Common heat treat treatments include carburizing and quenching and tempering.
This process is used to improve the machinability of forged P/M parts. Otherwise. its application is limited. Generally, forged parts are treated at temperatures appropriate for their combined carbon content, followed by cooling as rapidly as possible to approximately 705 “C ( I300 “F) for I/:! to 2 h. Optimum austenitizing temperatures for annealing plain carbon-iron compacts depend on combined carbon contents as follows: Temperature Combined C. %
T
0.20 0.30
900
OF
88.5 870 860
0.40 0.50
REFERENCES
1650 I625 1600 1580
I. H.E. Boyer. Secondary ASM
Operations
on P/M Parts and Products,
Vol 7,
Handbook
2. L.F. Pease 111. Mechanical Properties of P/M Materials, Vol 7, ASM Handbook: Ferrous Powder Metallurgy Materials, Vol I. ASM Handbook
3. ASM Metals Reference
Book. Third Edition. Edition,
ASM International
Relation of Carbon Content and Percentage Martensite to Rockwell C Hardness
Values of Case Depth Calculated by the Harris Equation 87OT (MoooF) Tie 2 4 8 I2 I6 20 24 30 36
(I), It
mm
itl.
0.6-l
0.025
0.89 I .27 I .55 I .80 2.01 2.18 2.46 2.74
0.035
o.oso 0.061 0.07 I 0.079 0.086 0.097 0. IO8
Case depth(a), after carburiziig 900°C (165OT) mm in. 0.76 I .07 I.52 I.85 2.13 2.39 2.62 2.95 3.20
0.030 0.042 0.060 0.073 0 084 0.09-l 0.103 0.1 I6 0. I26
at: 925°C (17OOT) mm 0.89 1.27 I.80 2.21 2.5-l 2.8-l 3.10 3.48 3.81
in. 0.035
0.050 0.07 I 0.087 0.100 O.ll2 0.122 0.137 0.150
(a) Case depth: mm = 0.635 &(case depth: in. = 0.025 6) for 925 “C (I700 “F); 0.533 \I;(O.O2 I Jr) for 900 “C ( 1650 “F); 0.157 \I;rO.Ol8 &) for 870 “C (1600 OF). For normal carburizing(~turatedaustenite at the steel surface while at temperature)
Heat Treating
Iron Casting
and P/M Steels / 855
Case Depth vs Time for Carbonitriding
P/M Parts
Typical Furnace for Gaseous Nitrocarburizing
Typical
Compositions
hlaterial PA4 iron P/M steel P/M copper iron P/M copper steel
P/M iron-copper PA4 iron-nickel PAI nickel steel P/M iron-nickel P/M nickel steel P/M iron-nickel P/h1 nickel steel P/M infiltrated steel
of Ferrous
hlPIF F-0900 F-OCKIS F-0008 FC-0200 FC-0205 FC-0308 FC-0505 FC-0508 FC-0808 FC- 1000 M-0200 M-0205 FN-0208 FN4400 FN-0405 FN-0408 FN-07cHIl M-0705 FN-0708 FX-1005 FX-1008 FX-2000 FX-2005 FX-2008
P/M Structural Desiguation(a) ASThl
B310,classA B3lO.classB B3lO.classC B 126, Fade I
Materials
SAE m. class I 853. class 2 853. class 3 864, grade I. class 3
B 426. grade 2 864. grade 2. class 3 864. grade 3. CI~LSS 3 B 426. grade 3 B 426. grade 4 864, grade 3. class 3 B 222: B 439. grade 3 862 B 181. grade I. class A B 184. grade I. class B B 484, grade I, class C B 484. grade 2, class A B 384. grade 2. class B B 484, grade 2, class C B 48.1.grade 3. class A B 48-t. grade 3. class B B 481. gnde 3. class C B 303. class A B 303. class B B 303. class C
870 872
C 0.3 tn3x 0.3-0.6 06 I .O 0.3 max 0.3-0.6 0 6- I .O 0.3-0.6 0.6-I .O 0.6-I .O 0.6-0.9 0.3 max 0.3 mar 0.3-0.6 0.6-0.9 0.3 max 0.3-O 6 0 6-0.9 0.3 max 0.3-0.6 0.6-0.9 0.3-0.6 0.6-I .O 0.3 max 0 3-0.6 0.6. I .O
hlPlFcomposition limits and ranges(b), % Ni CU
I .o-3.0 I .o-3.0 I .o-3.0 3.0-5.5 3.0-5.5 3.0-5.5 6.0-8.0 6.0-8.0 6.0-8.0
I s-3.9 1.5-3.9 1.5-3.9 4.0-6.0 4.0-6.0 6.0-I I.0 18.0-22.0 95IO.5 2.5 max 2.5 miix 2.5 max 2.0 max 2.0 max 2.0 max 2.0 max 2.0 mar 2.0 max 8.0-14.9 8.0-14.9 lS.O-25.0 15.0-25.0 IS.O-25.0
Fe 97.7-100 97499.7 97.099. I 93.8-98.5 93.5-98.2 93. I-97.9 91.4-95.7 91 .o-95.4 86.0-93.4 7S.l mm 87.2905 92.2-99.0 91.9-98.7 91.6-98.4 90.2-97.0 89.9-%.7 89.6-%.4 87.7-94.0 87.4-93.7 87. I-93.4 80.5-91.7 80.1-91.4 70.7-85.0 70.4-84.7 70.0-84.4
(a) Designations listed are nearest comparable designations: ranges and limits may vary slightly between comparable designations. (b) MPfF standards require that the total amount of all other elements be less than 2.O‘Z. except that the total amount of other elements must be less than 4.W in infiltrated steels
856 / Heat Treaters Guide Typical Mechanical Properties of Ferrous P/M Materials MPIF Designation F-0000
F-0005
density suffii(a) N P R s T N P R S
F-0008
N P R S
FC-0200
FC-0205
P R s P R S
FC-0208
N P R S
FC-0505
FC-0508
FC-0808 FC-1000 M-0200
FN-020.5
N P R N P R N N R S T R S T
FN-0208
R S T
M-cuoo
FN-0405
R S T R
Condition(b) AS AS AS AS AS AS AS AS HT AS HT AS HT AS HT AS HT AS HT AS AS AS AS AS HT AS HT AS HT AS HT AS HT AS HT AS AS AS AS AS HT AS AS AS AS AS AS AS HT ss HT ss HT AS HT AS HT AS HT AS AS AS AS HT
Tensile strength hCPa ksi
Yield strength MPa ksi
110
75 95 II0 1.50 I80 10s I-10 160 395 195 51s 170
II II I6 2’ 26 IS 20 23 47 28 75 25
205
30
250
36
275 625 I IS I-15 I60 235 260 560 310 655 20s
40 91 I7 21 23 3-1 38 81 45 95 30
280
II
330
18
399 655 20s 290 380 295 395 -180 480
57 95 30 42 55 43 57 70 70
I25 170 205 160 450 215 605 255 725 20s 650 280 880 31.5 IO70 I50 205 30 I80 650
I8 25 30 23 65 31 88 37 10s 30 91 II I28 so IS5 22 30 36 26 9-l
130 165 205 27s 125 170 220 415 295 550 200 290 Z-10 -loo 290 510 395 650 160 205 ‘55 27s 31s 585 -12.5 690 22.5 295 310 380 41s 550 550 690 240 315 455 330 115 180 51s 250 205 I95 260 310 3s 565 315 760 120 925 330 690 450 930 S-1.5 II05 250 340 430 310 770
I6 I9 2-l 30 10 I8 25 32 60 13 80 29 12 35 58 42 7-t 57 94 23 30 37 40 so 85 62 IO0 33 13 45 5s 60 80 80 IO0 35 SO 66 48 62 70 7s 36 30 28 38 45 37 82 so II0 61 13-I 18 100 65 I35 79 160 36 49 58 1s II2
tab For density range.(b) AS. zu sintrred; SS. sintered and sized: HT. heat treated. tprcall) Llnnotshed Chxpy test. (d) Estimated as 38’1 ol’tensile strength (e) X indicates inhltratrd
Elongation in25mm (I in.), 9E 2.0 2.5 5 9 I5 I.0 I.5 2.5 0.5 35 OS 0.5
atrstrnltizcd steel
Fatigue strength MPa ksi
Impact energy(c) J ft lb
10 so 60 80 105 -IS 65 85 IS4 II0 210 75 II0 90 150 I IO I95 IS0 ‘45 60 80 95 10s 130 220 I60 260 85 II0 11s 11.5 IS5 ‘IO 210 260 90 I30 170 I’S 160 I85 I95
h(d) 7(d) 9tdj II(d) l5td) 7td) IOtd) 12(d) 23td) 16td) ?Otd) I Itd) 16(d) I3idl ‘I(d) Iltd) 281dl 22(d) 36(d) 9td) II(d) 14(d) IS(d) 19(d) 31(d) 24(d) 38tdj l3td) Ihld) 17(d) 21(d) 23(d) 30(d) 30(d) 38(d) l3tdj l9tdt 25(d) 18(d) Ytdj 27(d) 29rdr
1. I 6. I I3 20 3-l 3.J 1.7 6.8
75 105 I25 I05 22s I-10 305 I65 370 130 27.5 I80 370 ‘20 415 9s I10 I60 I25 310
II I5 IS I5 33 20 4.4 2-t s-1 I9 40 26 s-1 33 60 I-1 20 23 I8 4s
I9 -13 6S II 8.1 2-1 71
I2
30 4.5 9.5 IS 3 2.5 3.5 5.0 9.0
2.7
2.0
4. I
30
4.7
3.5
9s
;.il
7.5 9.5 23 4.7 7.5
5.5 7.0 I7 3,s 5.5
I3
9.5
3.-l
2.5
-I. I
3.0
6.8
5.0
I’I
8.0
;.‘I 6.1 68 -I. I -1.7
3.0 -1,s S.0 3.0 3.5
6.1
4.5
3 38 II 8. I I9 I6 30 2-l 23 47 68 II 8. I
1;’ 31 50 IO 6 I8 I6 32 28 a 6 I4 I2 -3-l ii I6 35 so IO 6
Appawot hardness IO HRH 70 HRH 80HRH IS HRB 30 HRB 5 HRB 20 HRB 45 HRB IOOHRB 60 HRB 25 HRC 35 HRB WHRB SO HRB IOOHRB 65 HRB 25 75 HRC HRB 30 HRC 80 HRH IS HRB 30 HRB 35 HRB 60 HRB 30 HRC 75 HRB 35 HRC 45 HRB 95 HRB 50 HRB 25 HRC 70HRB 39 HRC 80 HRB 10 HRC SOHRB 60 HRB 75 HRB 60 HRB 65 HRB 30 HRC 85 HRB 55 HRB 7OHRF 38 HRB 42 HRB 91 HRB SO HRB 3’HRC 70HRB 42 HRC 85 HRB 16 HRC 62 HRB 3-l HRC 79 HRB 15 HRC X7 HRB 47 HRC 10 HRB 60HRB 67 HRB 63 HRB 27 HRC
at 870 “C t 1600 “FL 011 quenched and tempered
Elastic modulus GPa 1Wpsi 70 90 II0 130 I60 70 90 II0 II0 130 130 70 70 90 90 II0 II0 130 130 90 II0 130 90 I IO I IO 130 130 70 70 90 90 II0 II0 I30 130 70 90 I I6 70 90 90 I I6
IO.5 I3 I6 I9 23 10.5 I3 I6 I6 I9 I9 IO.5 IO.5 I3 I3 I6 I6 I9 I9 I3 I6 I9 I3 I6 I6 I9 I9 IO.5 IO.5 I3 I3 I6 I6 I9 I9 IO.5 I3 I6 IO.5 I3 I3 I6
II5 l4S 160 II5 11s I-15 I45 160 160 II.5 11s I15 l-25 I60 160 11s I45 I60 11s 11s
I7 21 23 I7 I7 21 21 23 23 I7 I7 21 21 23 23 I7 21 ‘3 I7 I7
I hat 200 “C t100”F~.
tc)
Heat Treating Iron Casting and P/M Steels / 857 Typical Mechanical Properties of Ferrous P/M Materials (continued) hiPIF
Designation FhWlOS
(continued)
dens@ suffii(a) S T
M-C!408
M-0700
M-0705
S T
FX- IOOSte)
R S T T
FX-1008(e)
T
FX-2000(e) FX-XX(e)
T
FX-2008(e)
T
FN-0708(e)
T
Condition(b) AS HT AS HT AS AS AS AS AS AS AS HT AS HT AS HT AS AS AS AS HT AS HT AS AS HT AS HT
Tensile strength hlPa ksi
tieId strength hlPa ksi
-125
2-m
I060 510 I240 395 530 640 560 -+90 585 370 70s 525 965 620 II60 39s SSO 655 S70 830 6’0 895 450 515 790 585 860
62 IS-I 74 I80 57 77 93 52 71 85 51 I02 76 l-10 90 I68 57 80 95 83 I20 90 I30 65 75 II5 as 12s
Elongation in25mm (1 in.), 8
3.5
4.5
880 295 1060 290 390 370 205 275 330 2-m 550 330 760 390 895 280 380 155 440 740 515 72.5
I28 13 IS-l 42 5-l 68 30 10 48 35 80 18 II0 57 130 -!I 5.5 66 64 107 75 10s
34s 6.55 51.5 710
so 9s 75 107
I.0 6.0 I.5 I.5 3.0 1.5 2.5 4 6 2.0 0.5 3.5 I.0 5.0 I .s IS 1.5 3.0 4.0 I.0 2.5 60.5 I.0 I .s CO.5 I.0
(a) Fordensib range t b) AS, as sintered: SS. sintered and sized; HT. heat treated. t>picsll> austenitized Unnotched Charpy test. (d) Estimated as 384 of tensile strength. (e) X indicates inhluated steel
Typical Density Designations P/M Materials
and Ranges of Ferrous
Fatigue strength ksi MPa 16.5 11s 205 4.50 160 21s 25s l4.r 19s 210 I50 280 20s 385 250 500 160 220 260
Impact energy(c) J ft ‘lb
2-l
20
60 30 65 ‘3 31 37 II 28 31 22 II 30 56 36 65 23 32 38
II II I9 8.1 I-I 22 I6 28 35 I2 II 23 ‘0 33 27 8 I6 22 I9 9.5 I6 9.5 20 12.9 8.1 II 6.8
IS IO 30 I-l 6 IO I6 I?. 21 26 9 8 I7 IS 2-l 20 6 I2 I6 l-l 7.0 I2 7.0 IS 9.5 6.0 I0 5.0
Apparent hardness 72 HRB 39 HRC 8OHRB MHRC 72HRB 88HRB 9SHRB 60 HRB 72 HRB 83 HRB 69HRB 24 HRC 83HRB 38 HRC 90HRB 4OHRC 75 HRB 88 HRB 96HRB 75 HRB 3s HRC 8OHRB JOHRC 6OHRB 75 HRB 30 HRC 8OHRB 42 HRC
at 870 “C t 1600 “F). oil quenched and tempered
Elastic modulus GPa 101psi I45 l-15 I60 I60 11s 1-u 160 I15 l-15 160 II5 11s I15 I-45 I60 160 11s I15 160 I35 I35 I35 I35 I25 I25 I25 I25
I h at 200 “C (400 “FJ. (c)
Effects of Density on Elastic Modulus, Poisson’s Ratio, and Coefficient of Thermal Expansion of P/M Steels
Density of pure iron is 7.87 gkm3. MPIF density
Designation hIPIF density SUlliX
SUflh
ASTM tme(a) I [I rrr Iv V(C)
SAE me
Deosity, &/cm3
Itb) 2 3 J St<,
Less than 6.0 6.0 to 6.-l 6.4 to 6.8 6.8 to 7.2 7.3 to 7.6 7.6 to 8.0
(a) ASThl B 126 only: different density ranges used in ASThl B 310 and B -1X-t. (b, Densib range of 5.6 to 6.0 g/cm’ ii specified. tc) Minimum density of 7.2 g/cm’ is specified
II 21 23 23 I7 II 23 I7 21 23 I7 I7 21 ?I 23 23 I7 21 23 20 ‘0 30 20 ... I8 I8 I8 I8
N P R S T Theoretical
Density, g/cm3
GPa
lOpsi
Poisson’s ratio
Coefficient of thermal expansion, 10-w
5.6-6.0 6.0-6.1 6.4-6.8 6.8-7.2 7.2-7.6 7.86
72 90 II0 130 160 205
IO.5 I3 I6 I9 23 30
0.18 0.20 0.2 I 0.23 0.26 0.28
8.1 8.7 9.2 9.8 IO.4 II-12
Elastic modulus
858 / Heat Treaters Guide Typical Density Designations P/M Materials
Effects of Steam Treating on Density and Apparent Hardness of Ferrous P/M Materials hlP[F hfPtF designation F-0000
t%OO8
FC-0700
FC-0708
density suffix N P R hl P R N P R N P R
Density, g/cm’ steam treated Siotered 5.8 6.2 6.5 5.8 6.2 6.5 5.7 6.35 6.6 5.7 6.3 6.6
6.2 6.4 6.6 6. I 6.1 6.6 6.0 6.5 6.6 6.0 6.4 6.6
Apparent hardness Steam Sintered treated 7 HRF 32 HRF 15 HRF 4-l HRB 58 HRB 60HRB IlHRB 19HRB 58 HRB 52 HRB 72 HRB 79HRB
75 HRB 61 HRB 51 HRB IOOHRB 98 HRB 97 HRB 73 HRB 78 HRB 77 HRB 97 HRB 94 HRB 93 HRB
Microstructure. Atomized iron powder with 0.3% graphite added to yield 0.1 to 0.2% combined carbon (6.7 g/cm3). Pressed at 410 to 460 MPa (30 to 35 tsi) and sintered 30 min at 1120 “C (2050 “F) in dissociated ammonia. White regions are ferrite. Arrows E surround a colony of eutectoid (pearlite). Arrow P points to a pore. 2% nital. 545x
Microstructure. Surface finger oxides (arrows at upper right) and interparticle oxide networks forged material
(arrow near lower left) in a powder
and Ranges of Ferrous
Designation MPIF density suffix
ASThl type(a)
SAE type
Density, g/cm'
N
I
l(b)
P R S T
rr
2
irr IV VW)
-1 Sk)
Less 0~116.0 6.0 to 6.4 6.4 to 6.X 6.8 to 7.2 7.2 to 7.6 7.6 to 8.0
U
3
Note: Densit) ofpure Iron is 7.87gkm’. (a) ASThl B126onl~;differentdensiryranges used in ASThl B 3lOand B 1X-1. tb) Density range of5.6 to6.0gkm’ is specified. hlinimum density of 7.2 g/cm’ is specilied
Microstructure. Microstructure
Ic)
of sintered Fe-2Ni-0.5C alloy. Sintered for 30 min at 1120 “C (2050 “F). Arrows marked Ni outline nickel-rich particle. Arrow M, martensite or bainite at nickel-rich boundary. Arrows marked L, diffusion layer between nickel and pearlite. This is not unalloyed ferrite. Arrow F, ferrite. 4% nital etched
Heat Treating Iron Casting and P/M Steels / 859 Minimum and Typical Mechanical Properties of Ferrous P/M Materials Minimum strength values (in ksi) are specified by the suffix of the material designation given in the remaining columns.
Material designation code(a)
Ultimate strength MPa
ksi
0.2 % offset yield strength MPa ksi
Elongation in 25 mm (1 in.), a0
Elastic modulus GPa 1W psi
code in the first column of the table. Typical values
lhnsvene IWptUlT strength MPa ksi
Impact energy(b) J fl Ibf
Apparent hardness(c)
are
Fatigue strength(d) MPa ksi
Iron and carbon steel 12s 172 262 165 220 ‘62 415 483 550 200 240 190 393 448 517 585 655
F-OOOO-IOte) F-0000- I S(e) F-OOO@-X(e) F-0005 IS(e) F-0005-20(e) F-000%2S(e) F-COOS-SOHiF-OOOMOHT(D F-0005-70HT(D F-0008-20(e) F-0008-25(e) F-0008-30(e) F-0008-35(e) F-OOOS-SSHT(f) F-0008-6SHT(f1 F-OOO8-7SHT(f) F-OOOS-SSHT(f)
Iron-copper
90 12s I72 I25 I60 I93 w (ZZJ W I72 207 240 27.5
I3 I8 25 I8 23 ‘8 (La (LY (8 25 30 35 40
I.5 2.5 7.0
96.5 II7 l-11 96.5 I I-l 12-I II-t I20 130 83 100 III I30 I03 III I’S I35
I-l.0 17.0 20.5 14.0 16.5 IS.0 16.5 17.5 19.0 12.0 14.5 16.5 19.0 IS.0 16.5 18.0 19.5
‘48 345 655 330 430 52.5 725 817 965 350 -PO 510 690 690 793 895 1000
36 SO 95 48 6-t 76 IO5 120 I40 51 61 7-t 100 100 II5 I30 I15
-I 8 47 -t 53 6.8 -I 4.7 5.5 3.5 4 5.5 6.8 4 5.5
3 6 35 3 J 5 3 3.5 4 2.5 3 4 5 3 4
kJ (8 (8) (8
‘I%) ‘8 (!a ‘a
2.8
54.5
25 28 31 3-1 35 -to SO 60 70 80 90 100 35 SO 60 75 65 75 90 I05 44 58 71 58 68 82 55 30
I38 I60 180 200 240 27s 310 345
90 I03 1l.t I24 90 103 II7 I31 100 II0 I21 I31 83 I03 II7 I38 96.5 107 I21 I34 83 I03 I17 86 I03 I21 90 90
13.0 IS.0 16.5 18.0 13.0 IS.0 17.0 19.5 l-I.5 16.0 17.5 19.0 I20 IS.0 17.0 20.0 I-t.0 IS.5 17.5 19.5 12.0 IS.0 17.0 12s IS.0 17.5 13.0 I30
310 350 389 435 415
-Is 51 56 63 60
6 6.8 7.5 8 ~2.7
4.5 5 5.5 6 -2
@J G) (8 w 36 -17 56 SO 60 70 SO 26
I.0 I .5 I.5 2.0 cl.0 cl.0
655 517 793 65s 758 827 930 315 6’0 860 I070 655 760 895 1035 530 703 855 690 827 IO00 58s 365
;: 11s 9s II0 I20 I35 60 90 l2S I55 95 II0 I30 IS0 77 102 12-l 100 I20 I-l5 85 53
&I II 3.5 4.7 6 7.5 <2.7 2.7 6.8 9.5 3.5 -1.7 6 7.5 2
35 8 1.5 3.5 4.5 5.5 <7 2 5 7 2.5 3.5 4.5 5.5 4.5 3
kJ (is!) (is) w Z-JO 310 380 448
‘g) (8) 35 45 55 65
03 (g) (ET) (I3 248 325 385 345 415 483 34s 180
6.8 4 4.7 6 4 4.7
25 35 40 40 SO 60 70 90
II7 I72 105 172 105 No 275 (.a
I7 25 30 25 30 35 40 (a
I.5 4.0 6.5 IS 2.5 J.0 5.5
107 13-l I59 107 I28 I52 I65 107
IS.5 19.5 23.0 l5.S IS.5 22.0 24.0 15.5
5.50
80
350 690 860 1035 827
65 100 I25 IS0 I20
4OHRF 6OHRF SOHRF 25HRB 4OHRB 55 HRB 20 HRC(h) ‘2 HRC(h) 35 HRC( h) 3SHRB 50HRB 60HRB 70 HRB 22 HRC(i) 28 HRCiij 32 HRC(i) 35 HRC(i)
48 70 96 62 83 97 I60 185 207 75 90 II0 I50 172 200 220 250
7 IO I4 9 I2 I4 23 27 30 II I3 16 22 25 29 32 36
5 3 3.5 4.5 3 3.5
II HRB I8 HRB 26 HRB 36HRB 37HRB 48 HRB 60 HRB 72 HRB I9 HRC(h) 25 HRC(h) 31 HRC(h) 36 HRC(h) 50HRB 61 HRB 73 HRB 84HRB 20 HRC(i) 27 HRCii) 35 HRC(i) 43 HRCiii 51 HRB 62 HRB 72 HRB 60HRB 68 HRB 80 HRB 65 HRB ISHRB
70 75 83 90 90 I03 130 I60 185 207 235 262 90 I30 160 200 I72 200 235 275 II7 I.52 185 I52 180 215 145 75
IO II I2 I3 I3 I5 I9 23 27 30 34 38 I3 I9 23 29 25 29 34 40 I7 22 27 22 26 31 21 II
26.5
19.5 “’
75HRF
8 16.5 28.5 46 4.5
6.0 12.0 2 I .o 34.0 3.5
44 HRB 59 HRB 69HRB 78 HRB 23 HRC(i)
70 90 105 IO.5 130 I60 I85 235
IO I3 IS I5 I9 23 27 34
aad copper steel
FC-O200-IS(e) FC-OXIO-IS(e) FC-0200-21(e) FC-0200.24(e) FC-0205-30(e) FC-0205-35(e) FC-020530(e) FC-02OS--lS(e~ FC-0205~6OHT(O FC-0205.70HT(f) FC-0205-80HT( FC-020WQHT(f) FC-@208-30(e) FC-@208-40(e) FC-@08-50(e) FC-0208-60(e) FC-@OS-SOHT( FC-0208-6SHT( FC-0’208-SOHT( FC-0208-95HT(f) FC-0505-30(e) FC-O50S--lO(e) FC-050.5-50(e) FC-0508-40(e) FC-OSOS-.50(e) FC-OS08-6O(e) FC-OSOS--IS(e) FC-lCKK?Ote)
Iron-nickel
I8 25 38 24 32 38 60 70 80 29 35 42 57 65 7s 85 95
t)
0 f) f)
I72 I93 215 235 240 275 345 415 483 5.50 620 690 240 345 415 517 450 517 620 725 303 400 490 400 470 565 380 207
20 23 26 29 35 40 45 SO 2;;
and nickel steel
FN-OXO- IS(e) FN-0200-20(e) FN-03-0025(e) FN-020.5-20(e) M-0205-25(e) FN-0205-30(e) FN-0205-35(e) FN-020%80HTtf)
I72 240 275 275 345 415 483 620
(a) The s&ix of the material designation codes represent either the minimum yield strength or the minimum ultimate strength in ksi. For example. the minimum yield strength of F-0000- IO is IO ksi. while Ihe minimum yield strength of F-0000- IS is IS ksi. (b) Unnotched Charpy test. (c) Where applicable. the matrix (convened) hardness is also given in the footnotes. (d) Fatigue limil for IO’cyctesfrom reverse-bending fatigue tests. (e) The suftix numbed kpresenls the minimum yield strength (in ksi) for the material in the&-sintered condition. (f)The s&ix number for heat-treated (HT) materials represents the minimum ultimate tensile saength in ksi. Tempering temperature for heat-treated materials is 175 “C (35OoF).(g)Yieldsopngthandultimatetensilesuengtharrapproximatelythesame for heat-treated materials. (h)Oramarrix (convened) hardnessof HRC. (i)Oramaaix(converted)hardnessof6OHRC.~)Oramatrix(convened)hardnessofS5 HRC.(k)Oramarrix(con~erted)hardnessof57HRC.(I)AII~~brlsedonsingle-passinfilaation.(m)Codes for the stainless sleel designations: NI. nitrogen alloyed, with good strength and IOH elongation: N2. nitrogen alloyed. with high strength and medium elongation: L, low carbon. with lower strength and highest elongation: HT. marlensitic grade. heat treated and highest strength
860 / Heat Treaters Guide Minimum and Typical Mechanical Properties of Ferrous P/M Materials
(continued)
Minimum strength values (in ksi) are specified by the suffix of the material designation given in the remaining columns.
Ultimate Material designation code(a)
SttWlgth
MPa
ksi
Iron-nickel and nickel steel (continued) FN-o2os-losHT(n 827 I20 FN-0205- I3Olwf) FN-ozos-lSSHT(f, M-0205- I8OHT( I-) FN-0208-30~ FN-0208-35(e) M-0208-W) FNO208-4S(r) FN-0208-50(r) FN-0208-8OHT( Q M-0208. I OSHT( 0 FN-0208- I3OHT( 0 Mc’208I SSHT( 0 FN-0208- I 8OHT( f) M-0105-25(e) FN-0405-35(e) FN-040515(e) FN-0405.80HT(f) FN-0405.105HT(fJ FN-0405-I 30HT(fJ FN-0405-IssHT(f) FN-0405I80HT(n FN-0308-35(e) Fl’-04084(r) FN-0408-55(e)
Low-alloy steel FL-UOS-80HT( t) FL-UOS- IOOHT(fl FL3’05I ZOHT(fl FL-QOS-I-u)HT(f) FL460580HT( f) n-4605-lOOHT(f, FLJho.s- I2OHT( f) ~~460s-l40~~(n
Copper-infiltrated FX- 1000-25(e) FX-lOOWO(E) FX-1005-I IOHT(fJ FX-1008-SO(c~ FX-1008-I loHT(n Fx-2ooo-25(e) FX2005-4S(e) FX-2005.9OHT(f) FX-2008-60(r) Fx-2008-90HT~n
0.2 % offset yield strength hlPa bi
(8) (?) (81 W
loo0 II00 1275 310 380 483 SSO 620 620 827 1000 II70 I345 27s -115 620 585 760 930 II00 1275 310 150 550
11s 160 I85 4.5 55 70 80 90 90 I20 I-15 170 19s -lo 60 90 85 I IO 135 160 185 45 65 80
27.5 310 345 380 (!Z) (8) &J w (PJ 205 275 345 ‘k) ‘@ w (d) (H 27s 315 415
620 760 895 1035 585 760 895 1070
90 I IO 130 IS0 85 II0 130 155
‘P) (8’ ‘g) (g, (8) (PJ ‘&J ‘g,
350 530 82.5 600 825 315 515 690 550 690
51 77 I70 87 I20 46 7s I 00 80 100
220 34.5
‘70 380 270 295 393 295 283 415 283 725
39 55 39 43 57 43 -II 60 II I05
240
Elongation in 25 mm (I in.), %
Elastic modulus GPa Iobpsi
code in the first column of the table. Typical values are
IYansverse rupture strength hWa ksi
Impact enera J ft. Ibf
Apparent hardness(c)
Fatigue strength(d) hlPa ksi
46 55
I.5 I .s 2.0 2.5 3.0 co.5
I28 I45 I52 I65 I I-I I28 l-15 I59 I65 II-1 128 I31 IS2 I65 96 9 I34 165 96.S IZI I34 IS9 165 100 I28 I52
18.5 21 0 22.0 24.0 16.5 18.5 21.0 23 0 Z-l.0 16.5 l8.S I95 22.0 24.0 l-I.0 19.5 ‘4.0 I-I.0 17.5 19.5 23.0 110 I-1.5 18.5 22 0
1100 1310 I-180 I725 585 725 895 1070 II70 827 103.5 127s 1515 1725 -IS0 827 I205 793 IO00 I380 I690 1930 517 793 1035
I60 I90 215 30 8s 105 130 I55 170 I’0 I50 18s 220 250 65 I20 I75 II5 l-l5 200 245 280 75 II5 I50
6 8 9.5 I3 7.5 II IS 21.5 28.5 5.5 6 1.5 9.5 II 6 I95 4s 5 55 6.8 8.8 I3 17.5 is IO IS
-I..5 60 7.0 9.5 5.5 x.0 I I.0 16.0 21.0 -lo 1.5 9.5 7.0 8.0 -l.s l-t.5 33.s 4.0 50 h.S 9.5 13.0 1.0 7.5 I I.0
29 HRCij) 33 HRC(j) 36 HRC(j) 40 HRC(j) 63HRB 71 HRB 77HRB 83 HRB 8X HRB 26HRCtk) ?I HRC(k) 35 HRCYL) 39 HRC(k) -I2 HRC(L) 19HRB 71 HRB 81HRB I9 HRC(J, 25 HRC(j) 31 HRCtj) 37 HRClj) 10 HRC(j) 67 HRB 78 HRB 87 HRB
315 380 -120 480 11s I15 I85 205 235 335 315 380 150 510 105 160 235 220 290 3SO 120 1X0 II5 170 305
61 70 I7 21 27 30 31 3-l 46 55 65 74 I5 23 31 32 12 51 61 70 I7 25 30
(8) (!zJ (8) (a
117 I30 IS0 I72 II5 125 I38 IAX
17.0 19.0 ‘2.0 25.0 16.5 18.0 20 0 21.5
930 II00 1275 I-180 895 I I35 13-15 IS85
13.5 160 I85 21.5 130 I65 195 230
4.7 55 55 6 -1.7 h 8 9.5
3.5 1.0 -IO 4.5 3.5 -13 6.0 70
28 HRC(i) 32 HRC(iJ 36 HRC(i) 39 HRC(i) 2-t HRC(i) 29 HRC(i) 31 HRC(i) 39HRC(i)
33.5 290 338 393 220 290 338 -I05
31 42 49 57 32 32 49 59
3’ so (8’
(&T) 70 w
7.0 4.0
II0 II0 II0 II0 II0 103 103 I03 103 I03
160 I60 160 160 16.0 IS.0 Ii.0 IS.0 15.0 I5 0
910 I090 I-l-I.5 II-l.5 I305 993 1020 II80 1075 1095
I32 IS8 210 I66 I89 I-t-4 I-18 I71 I56 I59
3-l 17.5 95 135 88 20 10.8 9.5 95 6.8
25 I3 7 IO 6.5 5 8 7 7 5
65 HRB 82HRB 3X HRC(j) 89 HRB 43 HRC(h) 66 HRB 85HRB 36 HRCYj) 90HRB 36 HRC(h)
130 200 315 22s 31s II.5 200 260 205 260
I9 29 46 33 46 I7 29 38 30 38
32 -12 I7 38 -IO I8 34 39 20 (iz’
0.5 5 17.5 OS 10 23 05 I0 I85
593 675 565 772 875
86 98 81 II? I27
4.7 33
3.5 I9
5.5 34
1’ 25
62 HRB 63 HRB 2lHRB 61 HRB 62HRB
715 860 550 780
” 108 125 80 II3
6.8 38 47 35
5”’ 2x 35 25
59HRB 62 HRB 2OHRB 23 HRC(j)
(8) (LY (8) w 35 40 15 50 55 @J (@ I&! (PJ w 30 10 SO (g) (.EJ ‘8) (g’ ‘?’ 40 SO 60
ig) !!g ‘@, G’
iron and steel(l)
I@’ 415 (U ‘55 415 ‘?) 483 (8)
60 ‘a 37 60
Stainless steel(m) SS-303N I -25(e) SS-303N2-35(r) ss-303L- I Z(e) SS-3MN 1-30~1 SS-304N2-33(e) SS-301L- 13(e) SS-316Nl-25(e) SS-316N2-33(e) SS.316L-IS(r) ss3I040HT(f)
2’0 290 II5 260 ‘75 I75 235 270 I38 (8)
___
(a) The suffix of the material designation codes represenf either the minimum,!ield strength or the minimum ultimate strength In Lsi. For example. the minimum yield strength of F-0000.IOis IOksi. while the minimum yield strength of F-OOOO- IS is IS I\si. I b) llnnotchrd Charpy lest. (L‘) H here applicable. the matrix (convertedl hardness is also given in the foomotes. (d) Faugue limit for IO’qcles from reverse-hcnding faugue tests. (c)The suffi\ numhcr represents the minimum ! ield strength (in lw) for the material in the assintered condition. (f) The suffix numher for heat-treated (HT) materials represents the mirumum ultimate tensile strength in ksi. Tempering tcmperamre for hear-trealrd materials is 17.5 “C (350°F). (g) Yieldstrengthandultimatetensilestrengthareapproximatel~ thesame for heat-treated materials. (h)Ora matrix Iconverted) hardnessofS8 HRC. (i)Oramatrx (convened)~~essof60HRC.(i)Oramatrix(con~ertrd)h~dnessofSSHRC.~k~Oramatris(con~ened~h;lrdnrssof57HRC.tl~.~IIdatah~edonsingle-prlssinliltration.(m)Codes for the stainless steel designations: NI. nitrogen alloyed, with good strength and Ion elongation: N2. nitrogen alloyed. with high wkvgth and medium elongation; L. low carbon. with lower strength and highest elongation: HT. martensitic grade. heat treated. and highest strength
Heat Treating Iron Casting and P/M Steels / 861 Precision of Rockwell Apparent Hardness Readings on P/M Parts laboratories tested identical coupons. If similar but different coupons were to be compared, variability ences between respective readings would be expected.
All
would be Increased, and larger differ-
Reoeatabilitv(a) hIPIF material designation
Number of laboratories
Density, g/cm3
CZF-2002
7.92 6.7-t 6.63 7.-15 6.90 690 6.29 6.29 689 6.89
F-0000 FC-0208 FX-2008 l=lJ6os-HT l=lA6os-HT FC-0208-HT FC-0208-HT FN-0208.HT FN-0208.HT (a) Rcpcatabilit)
and reproducibilib
9 9 9 9 8 8 IO IO IO IO dclincd
according
Average apparent hardness 82.5 HRC 63.-t HRF 70.8 HRB 86.-t HRB 107 2 HRBtb) 31.6 HRC 97. I HRBfb) ISlHRC 105.3 HRBtbt 30.5 HRC
to XSThl
One reading
Average of six readings
1.7
07 I.6 I.8 1.8 0.8 0.9 I.3 1.7 I.2 I.5
4.0 -I.5 4.3 I .9 2.2 3.1 12 2.9 3.8
Average-densi ultimate tensile strength hlPa bi
hlaterial
Blackening(a)
F-OfXJO
None Light HuaV) None
138 15-l I.52 12-l
Xl0 22.3
None Light Hea\ y None
I32 139 13-t 173
19.1 20.2 I9 5 25 I
-17.8 19.0 48.8
None Light Hea\? None
711 13-t II6 ‘II
30.6 19.-l 16.8 3S
-13.2 -15.6 15.1
None Light Heav) None
‘72 I92 I93 31s
39 5 27 9 28.0 50.0
46.7 -18.0 -t8.l
None Light Hea\ 5 None
331 208 205 34.5
X3.0 30.2 29.8 SO
13.2 -15 I 44.9
None Light Heat 1 None
161 105 383 -13-t
66.8 S8 8 55.5 63
-17.2 48.5 -t7.6
Standard 35 F-0000
Stildiid 35 F-0098
Standard 3s F-0008
22.1 18.0
12.7 -ts.o 44.6
2.2
0.9 I.8 2.3 2.0 I.3 I.3 I.8
‘IA 5.7 4.9 3.1
3. I 4.4 5.1 1.1
2.1 I.7 I .9
4.6
E 691 (br HRB scale with I 6 mm f r/r6 in. I diam carbide ball indentors
Comparison of Average Mechanical Properties of Steam-Blackened Typical Standard 35 Ultimate tensile strength MPa ksi
Reproducibiity(a) (95 S-confidence jimits) One Average of six readings reading
(95% confidence limits)
6 20 6.S2 6.-17
6.93 7.10 7.08
6.26 6.61 b.59
6 78 6.96 6.97
Elongation in25mm (1 in.). 5%
P/M Materials with As-Sintered Properties and
II-ansterse rupturestrength ksi hiPa
Impact enerR) ft. Ibf J
6.-t I8 I .2 I .5
330 367 -13-l 218
-t7 9 53 2 63.0 36.0
5.4 2.7 2.7 1. I
1.0 20 2.0
3.1 0.6 0.8 2.5
395 -196 545 3-1s
57.3 72.0 79. I so 0
5.x 3.0 3.0 8.1
-1.3 2.2 2.2 6.0
I .5 0.1 O.-l 4.5
193 -134 150 120
65 7 63.0 65.2 61
3.6 2.3 T-1 -1.1
2.7 I .7 I .8 3
I6 0.3 0.X
665 656 752 600
96.-l 95 I IO9 87.0
-I.3 3.0 3.1 6.1
32 2.2 7-j 15
I .2 O.-l 07 cl.0
68-l 606 73s 620
99.2 87 9 IO7 90
1.7 27 2.7 2.7
3.5 2.0 20 2.0
I .7 I.2 03
952 92-l IO-IO 903
13X 13-t 151 I31
8.8 S.8 5.7 75
6.5 -1.3 -1.2 5.5
30
0.2 k offset yield strength
MPa
690
103
170
230
ksi
Eardnesa, ERB
IO
37 88 85 4OHRF
IS
52 90 88 6OHRF
25
69 IO8 106 50
32
87 II0 108 65
40
87 II2 II0 61
52
95 Ill 108 75
35 F-0208
Standard 35 F-208
Standard 35
tat None. as sintered; tcmpsrature
Light blackening.
’_ h exposure
6.27 6.5-t 651
6.85 7.03 69
in S38 “C I 1000 “Fr sttam: hraq
blackening.
275
360
-l h exposure in 538 “C t IOOII “FJ wzam. tb) Lfnnotched
Charpy
test at room
862 / Heat Treaters Guide Applications Materialand specitkatioo
of Ferrous P/M Materials MPIFdensity snffii
designation
P/M iron F-0000-N
through T 0.3 C max
N R’ S T
P/M steel F-CKtOS-N through T: 0.3 to 0.6 C
N P R S
P/M steel F-0008-N
through T 0.6 IO I .O C
N P R S
P/M copper iron FC-0200-P
As sintered As sintered As sintered Heat treated As sintered Heat treated
Structural (moderately loaded gears. levers. cams): smtctutaI levers. and cams requiring wear resistance t as heat treated
(moderately
loaded gears.
As sintered Heat treated As sintered Heat treated As sintered Heat treated As sintered Heat treated
Structural (moderately loaded gears. levers. cams); structural leten. and cams requiring wear resistance) as heat treated
(moderately
loaded gears,
Bearings or mechanical components Mechanical components
through S: I .5 to
P R
As sintered Heat ueated As sintered Heat treated
Bearings or mechamcal components Mechanical components
As sintered Heat treated As sintered Heat treated As sintered Heat treated As sintered Heat treated
Bearings or mechanical components Mechanical components
through S: I .S IO
N P R S
through S: 4.0 to
N
6.0Cu. 0.3 IO0.6 C P R P/M copper steel FC-O.508-N through R: 1.0 to 6.OCu.0.6 to I .OC
Mechanical
components
N
As sintered
Mechanical
components
N
As smtered
Beatings or mechanical
As sintered As sintered As sintered As sintered Heat treated Sintered and sized Heat treated Sintered and sized Heat treated
hlechanical
R 6 to I I Cu. 0.6
P/McopperimnFC-WOO-N:9.5tolO.SCu.
As sintered Heat treated(a) As sintered Heat treated(a) As sintered Heat treated(a) As sintered Heat treated(a) As sintered Heat aeared As sintered Heat treated(a)
N P
P/M copper steel FC-O808-N: to I.OC
Structural ilightly loaded gears); magnetic (motor pole pieces): self-lubricating bearings: structural wear-resisting (small levers and cams) as carbonitrided
As sintered As sintered As sintered
S
P/M copper steel FCOSOS-N
sintered sintered smtered sintered sintered
P R S
3.9Cu. 0.3 to 0.6 C
P/M copper steel PC-0208-N 3.9Cu.0.610 I.OC
As As As As As
through S: I S to
3.9cu.o.3cmilx P/M copper steel FC-0205-P
Application
Condition
components
0.3cmax P/M iron-nickel FN-O200-R through T: I to 3 Ni, 2.5 Cu max. 0.3 C max
t T R S
T
P/M nickel steel FN-0208-R through T I IO 3 Ni, 0.6 IO 0.9 C. 2.5 Cu max
R S T
(a) Generally
heat treated for wear resistance rather than strength
As sintered Heat treated As sinteted Heat treated As sintered Heat treated
components
(can be case hardened)
Structural (couplings) as sintered: structural. wear resisting (oil pump gears and heavily loaded support brackets) as heat treated: structural. wear and impact resisting (oil pump gears to 3000 psi and heavily loaded transmission gears)
Mechanical
components
Heat Treating Iron Casting and P/M Steels / 863 Applications
of Ferrous P/M Materials
(continued)
MPIFdensity
Material and specitkatioo designation
Application
Condition
SUfliX
P/M iron-nickel FN-@IO@-R through T: 3 to S.SNi.0.31o0.6C.2.0Cumax
R
As sintered
hlechanical
components
P/M nickel steel FN-OJOS-R through T: 3 to 9 Ni. 0.3 to0.6C. 2.OCu max
R
As sintered Heat treated As sintered Heat seated As sintered Heat treated
Mechanical
components
S T
(can be case hardened)
P/M nickel steel MO408-R through T: 3.0 to 5.0 Ni. 0.6 to 0.9 C. 2.0 Cu max
R S T
As sintered As sintered As sintered
Strwtural. wear resisting. high stress (planetary differential and transmission gears up to 6 hp) as heat treated;structural. Hear resisting. high stressand requiring welded assembly (welded assembly of pinion and sprocket) as carbonitrided
P/h4 iron-nickel M-0700-R Ni.O.3Cmax.2.OCumax
R
As sintered As sintered As sintered
Mechanical
components
As sintered Heat ueated As sintered Heat treated As sintered Heat mtated
hlechanical
components
As sintered As sintered As sintered
Mechanical
components
T
As sintered Heat treated
hlechanical
components
(special shapes)
T
As sintered Heat treated
Mechanical
components
(spectal shapes)
through T: 6 to 8
: P/M nickel steel M-0705-R through T: 6 to 8 Ni. 0.3 to 0.6 C. ?.OCu max
R S T
P/M nickel steel M-0708-R through T: 6 to 8 Ni. 0.6 1o0.9C. 2.OCu max
R ;
P&l intiltrated 0.3 to 0.6 C
steel FX- 1005-T: 8 to 11.9 Cu.
FX- 1008-T: 8 to 14.9 Cu. 0.6 to I .OC
(can he case hardened)
FX-2OOOT:
IS to 25 Cu. 10.3 C max
T
As sintered
Mechanical
components
FX-ZOOS-T:
IS to25 Cu. 0.3 to0.6C
T
As sintered Heat treated
Mechanical
components
FX-2008-T:
I5 IO 25 cu. 0.6 to I .oc
T
As sintered Heat seated
hlechanical
components
As As As As As As
51~ 303, mechanical components requiring secondary machining: type 3 16, structural, corrosion resisting. nonmagnetic (small gears. levers. cams. and other parts for exposure to sah water and specitic industrial acids); type 410, structural, corrosion resisting (small gears. levers. cams. and other parts where applications require heat ueating for wear resistance)
P/M awenitic ss-303-P SS-303-R SS-3 16-P SS-3 16-R SS-IIO-N ss410-P (a) Genenlly
stainless steel E Ft N P
sintered sintered sintered sintered sintered sintered
heat treated for wear resistance rather than strength
Effects of Density on Elastic Modulus, Poisson’s Ratio, and Coefficient of Thermal Expansion of Ferrous P/M Materials MPlF density SUffii
N P R S T
Theoretical
Density, g/cm’
CPa
1W psi
Poisson’s ratio
Coefficient of thermal expansion, lW/K
S.6106.0 6.0 lo 6.1 6.1 IO 6.8 6.8 to 7.2 7.2 to 7.6 7.86
72 90 II0 130 I60 205
IO.5 I3 I6 I9 23 30
0.18 0.20 0.21 0.23 0.26 0.38
8.1 8.7 9.2 9.8
Elastic modulus
10.4 II-12
864 / Heat Treaters Guide Green Density and Green Strength for Various Types of Iron Powders Apparent
Compaction pressure
density, g/cm’
Powder
MPa
tsi
Green density, g/cmJ
30 40 SO 30 40 SO 30 40 50 30 40 so 30 -lo so
6.2 6.6 6.8 6.55 6.8 7.0 6.5 67 6.9 6.6 6.8 7.0 63 6.7 6.95
Sponge(a)
2.1
410 550 690
Atomized
2.5
410 550
sponge(b)
Reduced(a)
2.5
Sponge(a)
2.6
Elecuolytic(c)
2.6
(a) Powders contained
690 410 950 690 110 550 690 310 550 690
I % zinc stearate blended in. (h) Powder contained
Mechanical Properties of Electrolytic Temperature T
OF
so0
930
600
Ill0
700
1290
780
I-135
0.75% zinc stearate blended in. (c) Isostaticall~
Green strength hlPa
psi
I-l 22 18 1.1 I9
2100 3200 4lc!o 1900 2700
I6 21 21 I9 25 ‘7 31 13 S-2
2300 3000 3500 2700 3600 3900 -1600 6NO 7800
pressed
Iron Powder Compacts Hot Pressed at 140 MPa (20 ksi) Dwell time at temperature and pressure, s SO 150 x50 SO IS0 -I50 SO IS0 1SO 50 I50 -IS0
Elongation in25mm (I in.). 8
Tensile strength hlPa
bi
I 80 176 27-l 25-l 281 336 330 395 397 373 361 365
26.2 2s 5 39 8 36.9 10.8 38.8 47.8 S7 3 57.5 5-l. I s2.4 52.9
0 0 I 0.5
Hardness, AB SO 51 63 62 77 80 90 95 I00 IO1 93 96
2 I I2 27 22 32 37
Effect of Hydrogen Chloride on Iron Sintered in Hydrogen Temperature OC
OF
950
17-10
1375
2505
Time, min 30 30 I20 IN 30 30 I’0 I20
Atmosphere. Sr,hydrogen chloride
Density, g/cm3 6.20 6.30 6.30 6.30 7.00 7.20 7.SO 7.80
Strength hlPa
ksi
I31 IS9 I38 IS9 I93 234 23-l 183
I9 23 20 23 28 3-l 3-l -II
Elongation a, 6 IO 6 IO II 20 I7 25
Heat Treating Iron Casting and P/M Steels / 865 Typical Mechanical Properties of P/M Forged Low-Alloy Steels All materials are in the hardened and tempered condition unless otherwise indicated
Ultimate tensile hlaterial
shvngth ksi hIPa
Processing
Fe-2hlChl-0.67Crahbt Fe-2hlChl-0.67Ctat
960
1393
590
86
1900
275.6
IS00
218
616
1110
Sinteredat 1315°C (2400 “Ft. repressed
701
101.7
I530
Sinteredat 1315°C (2400 “Ft. repressed
936
135.7
4130
Gas atomized. mesh
16-u)
Gas atomrzed. -65 mesh Wateratomized
45
Sintered at IXMI “C (2190°F)
IS86
I 040 938
Fe-1Ni-0.3SC
hfixcdelemental pnwdets
Fe-0 55Ni-0.32hlo0.47h1n-0.23Cr-0.3OC
Sintcred at I XO “C (2190°F)
0.2% yield strength lisi MPa
1070
230
1303
89.1
I89
Elongation Reduction in 25 mm in (I in.), % area, 8
Density, Fracture 7%of toughness (KI,) Aardness hfPa6 ksidio. theoretical 98HRB
I2
19HRC
-I.5 I-l
-I6
38
18
2@25HRc
I00
9
I3
39
29
20-25 HRC
100
5
3
IO
IO00
l-15
10
-lo
l3b
600
87
I3
44
117.9
970
I41
I7
37
I SO.8
Charpy V-notch impact enera ft. lb J
7.5
-lbHRc
19
45
100
7
5
55 HRC
36
33
100
7
5
12 HRC
37
34
100
36
26
3lO-3soHv
99
I3
31 HRC
99
16
3-t 99
873
I27
Fe-9Cu-0.34hln 0.13Ni-0.6SMo-0.3lC
I b75
245
1410
205
I3
31
I9
99
Fe-0.35hlnO.S7hloI .95Ni-O.SC
IXUJ
17-t
II70
lb?
IO
I9
30
99
‘IS
I331
193
6
IO
8
98
Fe-3CwO.SC-0.3s
1630 modikd
rat hlCh1 is a mmterallo)
Simered at I205 “C t22OO”F) containing
205
l-18
b.5
hln. 209 Cr. 20% hlo. and 75. C. tbt As-sinteredcondition
