13- Martensitic Stainless Steels.pdf

13 Martensitic Stainless Steels

The mar The martens tensit itic ic grad grade es are are so name named d beca becaus use e when when heat heated ed abov above e the the crit critic ica al tempe tempera ratu ture re,, 160 1600 0 F (870 C), and cooled rapidly dly, a metallurgic gical structure ure known as martensite is obtained. In the hardened condition the steel has very very high high stre streng ngth th and hard hardne ness ss,, bu butt to ob obta tain in op opti tima mall corr corros osio ion n resi resist stan ance ce,, ductility, and impact strength, the steel is given a stress relieving or tempering treatment, usually in the range of 300–70 0–700 0 F (149–37 9–371 1 C). Thes hese alloys are har hardenabl nable e because use of the phas hase transf nsforma ormattion from bo bod dy-c y-centered cubic to body-centered tetragonal. As with the low-alloy steels, this tran transf sfor orma mati tion on is therm thermal ally ly contr controll olled ed.. The FeFe-Cr ph pha ase diagram sug ugge gest stss that hat the maxim ximum chrom hromiium con on-tent would be about 12.7%. But the carbon content expands the  regi region on to the exte xtent that hat larger chrom hromiium conte ntents are possi ssible. Common mmon alloys are 410 41 0, con onttaining 12% chromiu mium and low carbo bon n and alloy 440 of 17% chromium with a high carbon content. The martensitic stainless steels are the strongest of all stainless steels, having strength to 275 ksi. But at such high stre streng ngth th leve levels ls they they lack lack du duct ctil ilit ity y. A har hardening temperature ure range depend pendss upo pon n the com ompo possition on,, bu butt in general the higher the quenching temperature, the harder the article. Oil quenching is preferable, but with thin and intricate shapes, hardening by cooli oling in air shou oulld be und nde ertaken. ken. Tempe emperring ing at 80 800 0 F (425 C) does not reduce the hardness of the part, and and in this this cond condit itio ion n the these allo alloys ys show show an exce except ptio iona nall resi resist stan ance ce to frui fruitt and and vege vegettable ble acids, ds, lye, ye, ammo mmonia nia, and other corr orroden dents to which cutlery may be sub subje ject cted ed.. The martensitic stainless steels fall into two main groups that are associ sociat ated ed with with two two rang ranges es of mech mechan anic ical al prop proper erti ties es:: low low carb carbon on comp compos osit itio ions ns 

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Copyright © 2003 Marcel Dekker, Inc.

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with a maximum hardness of about Rockwell C-45 and the higher carbon compositions, which can be hardened to Rockwell C-60. (The maximum har hardnes ness of both oth groups in the ann nne ealed cond ndiition is abou outt Rock ockwell C-24 C-24..) A carbon conte ntent of app pprroxim ximately 0.15 15% % forms the divid viding line between the two grou group ps. With a low carbon content the chromium content must also be low or the materials will not harden. At the higher carbon levels the chromium cont conten entt can can be rais raise ed to abou aboutt 18 18%. %. Howe Howeve verr, beca becaus use e of po pote tent ntia iall prob proble lems ms of carbide precipit pitation hig high chrom hromiium mar martensitic sta stainle nless ste steels are no nott usually tempered to the same degree as the low carbon types. The low carbon class contains types 410, 416, and 430. Properties, perf perfor orma manc nce, e, heat heat trea treatm tmen ents ts,, and and fabr fabric ica ation tion of thes these e thr three stai stainl nle ess ste steels els are sim similar, exce xcept for type 416 16,, which is a free-machinin ning grade whic hich has better better machina machinabili bility ty.. Types 440A, 440B, and 440C are high carbon alloys. There are three types that do not fit into either category: types 420, 414, and 431. The minimum carbon content for type 420 is 0.15%, but it is usu usually produce uced to a carbo bon n spe specific ification of 0.3– 0.4 0.4%. Althou oug gh type 420 will not harden to such high values as the 440 types, it can be tempered with withou outt subs substa tant ntia iall loss loss in corr corros osio ion n resi resist stan ance ce.. Cons Conseq eque uent ntly ly a comb combin inat atio ion n of har hardnes ness and du duc ctility can be achieved whic hich is suit uitable for cutl utlery. Types 414 and 431 contain 1.25 – 2. 2.50% nickel, which is enough to make make them aust ustenitic at ambie bient temper perature. By addin ding nickel to the com om-possition two purpose po oses are achieved. ved. The addit dition of nickel permit mits a hig higher her chro chromi mium um cont conten entt whic which h impr improv oves es corr corros osio ion n resi resist stan ance ce and and enha enhanc nces es no notc tch h toughness. If toug toughn hnes esss is impo import rtan antt in the the appl applic icat atio ion, n, mart marten ensi siti tic c stai stainl nles esss stee steels ls should not be heat treated or used in the range of 800–10 0–105 50 F (427–566 27–566 C) sinc since e they they are are subj subje ect to temp temper er brit brittl tlen ene ess. ss. Temp mper erin ing g is usua usuall lly y per perform formed ed abov above e this this temp temper erat atur ure. e. Tou ough ghne ness ss of the the mart marten ensi siti tic c grad grades es of stai stainl nles esss stee steell tend tendss to decr decrea ease se as the the har hardn dnes esss incr increa ease ses. s. Bec Because ause of this this,, high high--str strengt ength h (hig (high h carb carbon on)) type type 440A 44 0A has has low lower toug toughn hnes esss tha than type type 41 410. 0. Nic Nickel, kel, ho howe weve verr, incr increa ease sess toug toughhness, and type 414 has a higher level of toughness than type 410 at the same stre strengt ngth h leve level. l. Martensitic grades have a ductile–bri e–brittle transition temperature at whic which h no notc tch h du duct ctil ilit ity y drop dropss very very sudd sudden enly ly.. Th The e tran transi siti tion on temp temper erat atur ure e is near near room temperature, and at low temp mpe erature ure, abo bout ut 300 F (184 C), they beco become me very very brit brittl tle. e. Th This is effe effect ct depe depend ndss on comp compos osit itio ion, n, heat heat trea treatm tmen ent, t, and and other oth er vari variab able les. s. If no notc tch h du duc ctili tility ty is crit critic ical al at roo oom m temp tempe eratu rature re or belo below w, and and the the stee steell is to be used in the har hardene dened d con ondi dittion, careful evaluation is requ quiired. If the 

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material is to be used much below room temperature, the chances are that quenched and tempered type 410 will not be satisfactory. While its notch ductility is better in the annealed condition down to 100 F (73 C), another type of stainless steel would probably be a better choice. The fatigue properties of the martensitic stainless steels depend on heat treatment and design. A notch, for example, in a structure, or the effect of a corrosive environment can do more to reduce fatigue limit than alloy composition or heat treatment. Abrasion, or wear, resistance is another important property. In most cases, the harder the material, the greater the abrasion resistance. In applications where corrosion occurs, however, such as in coal handling operations, this may not be the case since the oxide film is continuously removed, resulting in a high corrosion rate. Other mechanical properties of martensitic stainless steels, such as compressive yield shear strength, are generally similar to those of carbon and alloy steels at the same strength levels. The moduli of the martensitic stainless steels (29  106 psi) are slightly less than the modulus of carbon steel (30  106 psi). Since the densities of the martensitic stainless steels are slightly lower than those of the carbon and alloy steels they have an excellent vibration damping capacity. Moderate corrosion resistance, relatively high strength, and good fatigue properties after suitable heat treatment are usually the reasons for selecting the martensitic stainless steels. High carbon martensitic stainless steels are not usually recommended for welded applications, although type 410 can be welded with relative ease. Hardening heat treatments should follow forming operations because of the poor forming qualities of the hardened steels. Type 410 is used for fasteners, machinery parts, press plates, and similar items. If greater hardness of higher toughness is required type 414 may be used, and for better machinability types 416 or 416Se are used. Springs, flatware, knife blades, and hand tools are often made from type 420, while 431 is frequently used for aircraft parts requiring high yield strength and resistance to shock. Types 440A and 440B are used for cutlery while type 440C finds application in valve parts requiring good wear resistance. 

I.

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TYPE 410 (S41000)

Type 410 stainless steel is heat treatable and is the most widely used of the martensitic stainless steels. Its chemical composition is shown in Table 13.1. This alloy, when heat treated, has high strength properties with good ductility. Type 410 stainless has a maximum operating temperature of 1300 F 


TABLE 13.1 Chemical Composition of Type 410 Stainless Steel

Chemical Carbon Manganese Phosphorus Sulfur Silicon Chromium Iron

Weight percent 0.15 1.00 0.040 0.030 1.00 11.50–13.50 Balance

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(705 C) for continuous service, but for intermittent service may be operated at a maximum of 1500 F (815 C). Table 13.2 shows the mechanical and physical properties of type 410 stainless. With time and temperature, changes in metallurgical structure can be expected for almost any steel or alloy. In martensitic stainless steels softening occurs when exposed to temperatures approaching or exceeding the original tempering temperature. Type 410 stainless, which is a 12% chromium alloy, has been known to display brittle tendencies after extended periods in the same temperature range. This phenomenon is called 885 F embrittlement, which has been discussed previously. The rupture and creep characteristics of type 410 stainless are shown in Table 13.3. Alloys for low temperature service must have suitable engineering properties such as yield and tensile strength and ductility. Many metals may have satisfactory ‘‘room temperature’’ characteristics but do not perform adequately at low temperatures. Low temperature brittle fracture can occur without any warning such as stretching, sagging, bulging, or other indication of plastic failure. Alloys that are ordinarily ductile may suddenly fail at very low levels of stress. Table 13.4 shows the mechanical properties of type 410 stainless at cryogenic temperatures. Note that the yield strength and tensile strength increase as the temperature decreases, but the toughness (Izod impact) drops suddenly. Type 410 stainless steel is used where corrosion is not severe such as air, fresh water, some chemicals, and food acids. Table 13.5 provides the compatibility of type 401 stainless steel with selected corrodents. Applications include valve and pump parts, fasteners, cutlery, turbine parts, bushings, and heat exchangers. Type 410 double tempered is a quenched and double tempered variation conforming to NACE and API specifications for parts used in hydrogen 

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TABLE 13.2 Mechanical and Physical Properties of Type 410 Stainless Steel

Modulus of elasticity  10 6 (psi) Tensile strength  10 3 (psi) annealed heat treated Yield strength 0.2% offset  10 3 (psi) annealed heat treated Elongation in 2 in. (%) annealed heat treated Toughness (ft-lb) annealed heat treated Density (lb/in.3) Specific gravity Specific heat (32–212 F) (Btu/lb F) Coefficient of thermal expansion  10 6 (in./in. F) at 32–212 F Thermal conductivity (Btu/ft2 /hr/ F/in.) Brinell hardness annealed heat treated 

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29 70 150 45 115 25 15 33 49 0.28 7.75 0.11

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5.5 173 150 410

TABLE 13.3 Rupture and Creep Characteristics of Type 410 (S41000) Stainless Steel

Temperature ( F/ C) 

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800/427 900/482 1000/538 1100/593 1200/649 1300/704 1400/760

Stress for rupture (ksi) in

Stress for creep (ksi) rate/hr of

1,000 hr

10,000 hr

0.0001%

0.00001%

54.0 34.0 19.0 10.8 4.9 2.5 1.2

42.5 26.0 13.0 6.9 3.5 1.5 0.6

43.0 29.0 9.2 4.2 2.0 1.0 0.8

19.5 13.8 7.2 3.4 1.2 0.6 0.4


TABLE 13.4 Mechanical Properties of Type 410 Stainless Steel at Cryogenic Temperatures

Test temp. ( F/ C) 

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Yield strength 0.2% offset (ksi)

Tensile strength (ksi)

Elongation in 2 in. (%)

Izod impact (ft-lb)

90 94 148

122 128 158

23 22 10

25 25 5

40/ 40 80/ 62 320/196

sulfide service. Type 410S has a lower carbon content (0.8%) and a nitrogen content of 0.60%.

II.

TYPE 414 (S41400)

Type 414 stainless is a nickel-bearing chromium stainless steel. The chemical composition is shown in Table 13.6. By adding nickel the hardenability is increased but not enough to make it austenitic at ambient temperatures. By adding nickel the chromium content can be increased, which leads to improved corrosion resistance. The nickel addition also increases notch toughness. Type 414 can be heat treated to somewhat higher tensile and impact strengths than type 410. The mechanical and physical properties are given in Table 13.7. Type 414 stainless steel is resistant to mild atmospheric corrosion, fresh water, and mild chemical exposures. Applications include high strength nuts and bolts.

III.

TYPE 416 (S41600)

Type 416 stainless steel is a low carbon class martensitic alloy, a free-machining variation of type 410 stainless steel. The chemical composition is shown in Table 13.8. It has a maximum continuous service operating temperature of 1250 F (675 C) and an intermittent maximum operating temperature of 1400 F (760 C). Table 13.9 lists the mechanical and physical properties of type 416 stainless steel. Type 416Se has selenium added to the composition and the sulfur quantity reduced to improve the machinability of any of the stainless steels. Refer to Table 13.10 for the chemical composition of type 416Se and Table 13.11 for the mechanical and physical properties. These alloys exhibit useful corrosion resistance to natural food acids, basic salts, water, and most natural atmospheres. 

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TABLE 13.5

Compatibility of Type 410 Stainless Steel with Selected Corrodentsa Maximum temp.

Chemical Acetaldehyde Acetamide Acetic acid, 10% Acetic acid, 50% Acetic acid, 80% Acetic acid, glacial Acetic anhydride Acetone Acrylonitrile Allyl alcohol Alum Aluminium chloride, aqueous Aluminum chloride, dry Aluminum fluoride Aluminum hydroxide Aluminum nitrate Aluminum oxychloride Aluminum sulfate Ammonium bifluoride Ammonium carbonate Ammonium chloride, 10%b Ammonium chloride, 50% Ammonium chloride, sat. Ammonium hydroxide, sat. Ammonium nitrate Ammonium persulfate, 5% Ammonium phosphate, 5% Ammonium sulfate, 10– 40% Ammonium sulfite Amyl acetateb Amyl alcohol Amyl chloride Aniline Antimony trichloride Barium carbonate, 10% Barium chlorideb Barium hydroxide Barium sulfate Barium sulfide Benzaldehyde Benzene Benzoic acid Benzyl alcohol


F

C

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60 60 70 70 70

16 16 21 21 21 X X

210 110 90

99 43 27 X X

150

66 X

60 210

16 99 X X X

210 230

99 110 X X

70 210 60 90 60

21 99 16 32 16 X

60 110

16 43 X

210

99 X

210 60 230 210 70

99 16 110 99 21

230 210 130

110 99 54

Maximum temp. Chemical Borax Boric acid Bromine gas, dry Bromine gas, moist Bromine, liquid Butadiene Butyl acetate Butyl alcohol Butyric acid Calcium bisulfite Calcium carbonate Calcium chlorideb Calcium hydroxide, 10% Calcium hypochlorite Calcium sulfate Carbon bisulfide Carbon dioxide, dry Carbon dioxide, wet Carbon disulfide Carbon monoxide Carbon tetrachlorideb Carbonic acid Chloracetic acid Chlorine gas, dry Chloride gas, wet Chloride, liquid Clorobenzene, dry Chloroform Chlorosulfonic acid Chromic acid, 10% Chromic acid, 50% Citric acid, 15% Citric acid, 50% Copper acetate Copper carbonate Copper chloride Copper cyanide Copper sulfate Cupric chloride, 5% Cupric chloride, 50% Cyclohexane Cyclohexanol Ethylene glycol

F

C

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150 130

66 54 X X X

60 90 60 150

16 32 16 66 X

210 150 210

99 66 99 X

210 60 570 570 60 570 210 60

99 16 299 299 16 299 99 16 X X X X

60 150

16 66 X X X

210 140 90 80

99 60 32 27 X

210 210

99 99 X X

80 90 210

27 32 99

TABLE 13.5

Continued Maximum temp.

Chemical Ferric chloride Ferric chloride, 50% in water Ferric nitrate, 10– 50% Ferrous chloride Fluorine gas, dry Fluorine gas, moist Hydrobromic acid, dilute Hydrobromic acid, 20% Hydrobromic acid, 50% Hydrochloric acid, 20% Hydrochloric acid, 38% Hydrocyanic acid, 10% Hydrofluoric acid, 30% Hydrofluoric acid, 70% Hydrofluoric acid, 100% Ketones, general Lactic acid, 25% Lactic acid, conc. Magnesium chloride, 50% Malic acid Methyl chloride, dry Methyl ethyl ketone Muriatic acid Nitric acid, 5% Nitric acid, 20% Nitric acid, 70% Nitric acid, anhydrous Nitrous acid, conc.

F

C

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X X 60

16 X

570

299 X X X X X X

210

99 X X X

60 60 60 210 210 210 60

16 16 16 99 99 99 16 X

90 160 60

32 71 16 X

60

Maximum temp. Chemical Perchloric acid, 10% Perchloric acid, 70% Phenolb Phosphoric acid, 50– 80% Picric acid Potassium bromide, 30% Salicylic acid Silver bromide, 10% Sodium carbonate, 10– 30% Sodium chlorideb Sodium hydroxide, 10% Sodium hydroxide, 50% Sodium hypochlorite, 20% Sodium hypochlorite, conc. Sodium sulfide, to 50% Stannic chloride Stannous chloride Sulfuric acid, 10% Sulfuric acid, 50% Sulfuric acid, 70% Sulfuric acid, 90% Sulfuric acid, 98% Sulfuric acid, 100% Sulfurous acid Toluene Trichloroacetic acid Zinc chloride

F

C

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X X 210

99 X

60 210 210

16 99 99 X

210 210 210 60

99 99 99 16 X X X X X X X X X X X X

210

99 X X

16

a

The chemicals listed are in the pure state or in a saturated solution unless otherwise indicated. Compatibility is shown to the maximum allowable temperature for which data are available. Incompatibility is shown by an X. When compatible, the corrosion rate is <20 mpy. b Material is subject to pitting. Source : Ref. 1.

IV.

TYPE 420 (S42000)

Type 420 stainless steel is a hardenable 12% chrome stainless steel with higher strength, hardness, and wear resistance than type 410. Table 13.12 shows the chemical composition and Table 13.13 the mechanical and physical properties. This alloy has been used for cutlery, surgical instruments, magnets, molds, shafts, valves, and other products.



Chemical

Weight percent

Carbon Manganese Phosphorus Sulfur Silicon Chromium Nickel Iron

0.15 1.00 0.040 0.030 1.00 11.50–13.50 1.25–2.50 Balance


Modulus of elasticity  10 6 (psi) Tensile strength  10 3 (psi) annealed heat treated Yield strength 0.2% offset  10 3 (psi) annealed heat treated Elongation in 2 in. (%) annealed heat treated Density (lb/in.3) Specific gravity Specific heat (32–212 F) (Btu/lb F) Thermal expansion coefficient  10 6 (in./in. F) at 32–212 F Thermal conductivity (Btu/ft2 /hr/ F/in.) Rockwell hardness annealed heat treated 

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29 70 200 45 150 25 17 0.28 7.75 0.11

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6.1 173 C-22 C-44


Chemical Carbon Manganese Phosphorus Silicon Chromium Molybdenum Iron

Weight percent 0.15 1.25 0.060 1.00 12.00–14.00 0.60a Balance

a

May be added at manufacturer’s option.


Modulus of elasticity  10 6 (psi) Tensile strength  10 3 (psi) annealed heat treated Yield strength 0.2% offset  10 3 (psi) annealed heat treated Elongation in 2 in. (%) annealed heat treated Toughness (ft-lb) annealed heat treated Density (lb/in.3) Specific gravity Specific heat (32–212 F) (Btu/lb F) Rockwell hardness annealed heat treated 


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29 75 150 40 115 30 15 33 49 0.276 7.74 0.11 B-82 C-43

TABLE 13.10 Chemical Composition of Type 416Se Stainless Steel

Chemical

Weight percent

Carbon Manganese Phosphorus Sulfur Silicon Chromium Selenium Iron

0.15 1.25 0.060 0.060 1.00 12.00–14.00 0.15 min. Balance

Type 420F (S42020) stainless is a free-machining version of type 420. It is hardenable and also exhibits higher strength, hardness, and wear resistance than type 410. The chemical composition will be found in Table 13.14 and the mechanical and physical properties in Table 13.15.

V.

TYPE 422 (S42200) 

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This alloy is designed for service temperatures to 1200 F (649 C). It is a high carbon martensitic alloy whose composition is shown in Table 13.16. It exhibits good resistance to scaling and oxidation in continuous service at 1200 F (649 C), with high strength and toughness. Mechanical and physical properties are shown in Table 13.17. Type 422 stainless is used in steam turbines for blades and bolts. 

VI.

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TYPE 431 (S43100)

The addition of nickel to type 431 provides improved corrosion resistance and toughness (impact strength). Table 13.18 shows the chemical composition, while Table 13.19 shows the mechanical and physical properties. This alloy finds application as fasteners and fittings, for structural components exposed to marine atmospheres, and for highly stressed aircraft components.

VII.

TYPE 440A (S44002)

Type 440A stainless is a high carbon chromium steel providing stainless properties with excellent hardness. Because of the high carbon content type


TABLE 13.11 Mechanical and Physical Properties of Type 416Se Stainless Steel

Modulus of elasticity  106 (psi) Tensile strength  103 (psi) annealed heat treated Yield strength 0.2% offset  103 (psi) annealed heat treated Elongation in 2 in. (%) annealed heat treated Density (lb/in.3) Specific gravity Specific heat (32–212 F) (Btu/lb F) Rockwell hardness annealed heat treated 

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29 75 150 40 115 30 15 0.28 7.75 0.11 B-82 C-43

440A exhibits lower toughness than type 410. The chemical composition is shown in Table 13.20. Type 440 has a lower carbon content than type 440B or 440C and consequently results in a lower hardness but greater toughness. The mechanical and physical properties are contained in Table 13.21. When heat treated, a Rockwell hardness of C-56 can be obtained.

VIII.

TYPE 440B (S44003)

When heat treated, this high carbon chromium steel attains a hardness of Rockwell C-58, intermediate between types 440A and 440C with a comparable intermediate toughness. Table 13.22 shows the chemical composition and Table 13.23 the mechanical and physical properties. Type 440B has been used for cutlery, hardened balls, and similar parts.

IX.

TYPE 440C (S44004)

Type 440C stainless steel is a high carbon chromium steel that can attain the highest hardness (Rockwell C-60) of the 440 series stainless steels. In the hardened and stress relieved condition, type 440C has maximum hardness together with high strength and corrosion resistance. It also has good abrasion resistance. The chemical composition is shown in Table 13.24 and the mechanical and physical properties in Table 13.25.



Chemical

Weight percent

Carbon Manganese Phosphorus Sulfur Silicon Chromium Iron

0.15 min. 1.50 0.040 0.030 1.50 12.00–14.00 Balance


Modulus of elasticity  10 6 (psi) Tensile strength  10 3 (psi) annealed heat treated Yield strength 0.2% offset  10 3 (psi) annealed heat treated Elongation in 2 in. (%) annealed heat treated Toughness, heat treated (ft-lb) Density (lb/in.3) Specific gravity Specific heat (32–212 F) (Btu/lb F) Coefficient of thermal expansion  10 6 (in./in. F) at 32–212 F Thermal conductivity (Btu/ft2 /hr/ F/in.) Rockwell hardness annealed heat treated 

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29 95 250 50 200 25 8 15 0.28 7.75 0.11

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5.7 173 B-92 C-54

TABLE 13.14 Chemical Composition of Type 420F (S42020) Stainless Steel

Chemical

Weight percent

Carbon Manganese Phosphorus Sulfur Silicon Chromium Molybdenum Iron

0.15 min. 1.25 0.060 0.15 min. 1.00 12.00–14.00 0.60 Balance

TABLE 13.15 Mechanical and Physical Properties of Type 420F (42020) Stainless Steel

Modulus of elasticity  10 6 (psi) Tensile strength  10 3 (psi) annealed heat treated Yield strength 0.2% offset  10 3 (psi) annealed heat treated Elongation in 2 in. (%) annealed heat treated Toughness, heat treated (ft-lb) Density (lb/in.3) Specific gravity Specific heat (32–212 F) (Btu/lb F) Coefficient of thermal expansion  10 6 (in./in. F) at 32–212 F Rockwell hardness annealed heat treated 

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29 95 250 55 200 22 8 15 0.28 7.75 0.11

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5.7 B-92 C-54


Chemical Carbon Manganese Phosphorus Sulfur Silicon Chromium Nickel Molybdenum Vanadium Tungsten Iron

Weight percent 0.2–0.25 1.00 0.025 0.025 0.75 11.00–13.00 0.5–1.00 0.75–1.25 0.15–0.30 0.75–1.25 Balance


Tensile strength, heat treated,  10 3 (psi) Yield strength 0.2% offset, heat treated,  103 (psi) Elongation in 2 in., heat treated (%) Specific heat (32–212 F) (Btu/lb F) Brinell hardness, heat treated 


Chemical Carbon Manganese Phosphorus Sulfur Silicon Chromium Nickel Iron

Weight percent 0.20 1.00 0.040 0.030 1.00 15.00–17.00 1.25–2.50 Balance


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145 125 16 0.11 320


Modulus of elasticity  10 6 (psi) Tensile strength  10 3 (psi) annealed heat treated Yield strength 0.2% offset  10 3 (psi) annealed heat treated Elongation in 2 in. (%) annealed heat treated Toughness, heat treated (ft-lb) Density (lb/in.3) Specific gravity Specific heat (32–212 F) (Btu/lb F) Coefficient of thermal expansion  10 6 (in./in. F) at 32–212 F Thermal conductivity (Btu/ft2 /hr/ F/in.) Rockwell hardness annealed heat treated 

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29 125 196 95 150 25 20 25 0.28 7.75 0.11

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TABLE 13.20 Chemical Composition of Type 440A Stainless Steel

Chemical Carbon Manganese Phosphorus Sulfur Silicon Chromium Molybdenum Iron

Weight percent 0.60–0.75 1.00 0.040 0.030 1.00 16.00–18.00 0.75 Balance


6.5 140 C-24 C-41

TABLE 13.21 Mechanical and Physical Properties of Type 440A Stainless Steel

Modulus of elasticity  10 6 (psi) Tensile strength  10 3 (psi) annealed heat treated Yield strength 0.2% offset  10 3 (psi) annealed heat treated Elongation in 2 in. (%) annealed heat treated Toughness, heat treated (ft-lb) Specific heat (32–212 F) (Btu/lb F) Rockwell hardness annealed heat treated 

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29 105 260 60 240 20 5 8 0.11 B-95 C-56

This stainless steel is used principally in bearing assemblies, including bearing balls and races.

X.

ALLOY 440-XH

This alloy is produced by Carpenter Technology, having a nominal composition as follows: Chemical

Weight percent

Carbon Manganese Silicon Chromium Nickel Molybdenum Vanadium Iron

1.60 0.50 0.40 16.00 0.35 0.80 0.45 Balance

This is a high carbon, high chromium, corrosion resistant alloy which can be described as either a high hardness type 440C stainless steel or a corrosion resistant D2 tool steel. It possesses corrosion resistance equivalent to


TABLE 13.22 Chemical Composition of Type 440B Stainless Steel



type 440C stainless but can attain a maximum hardness of Rockwell C-64, approaching that of tool steel.

XI.

TYPE 440F OR 440F-Se

This high carbon chromium steel is designed to provide stainless properties with maximum hardness, approximately Rockwell C-60 after heat treatment. However, the addition of sulfur to type 440F, or the addition of selenium to

TABLE 13.23 Mechanical and Physical Properties of Type 440B Stainless Steel

Modulus of elasticity  10 6 (psi) Tensile strength  10 3 (psi) annealed heat treated Yield strength 0.2% offset  10 3 (psi) annealed heat treated Elongation in 2 in. (%) annealed heat treated Specific heat (32–212 F) (Btu/lb F) Rockwell hardness annealed heat treated 


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29 107 280 62 270 18 3 0.11 B-96 C-55

TABLE 13.24 Chemical Composition of Type 440C Stainless Steel



type 440F-Se, makes these two grades free machining. Either of these two types should be considered for machined parts which require higher hardness values than possible with other free-machining grades.

XII.

13Cr-4N (F6NM)

F6NM is a high nickel, low carbon martensitic stainless with higher toughness and corrosion resistance than type 410 and superior weldability. It has

TABLE 13.25 Mechanical and Physical Properties of Type 440C Stainless Steel

Modulus of elasticity  10 6 (psi) Tensile strength  10 3 (psi) annealed heat treated Yield strength 0.2% offset  10 3 (psi) annealed heat treated Elongation in 2 in. (%) annealed heat treated Toughness, heat treated (ft-lb) Specific heat (32–212 F) (Btu/lb F) Rockwell hardness annealed heat treated 




29 110 285 65 275 14 2 5 0.11 B-97 C-60

been used in oil field applications as a replacement for type 410. F6NM has a chemical composition as follows: Chemical

Weight percent

Carbon Manganese Phosphorus Sulfur Silicon Chromium Nickel Molybdenum Iron

0.05 0.50–1.00 0.030 0.030 0.30–0.60 12.00–14.00 3.50–4.50 0.40–0.70 Balance

REFERENCES 1. 2. 3. 4.

PA Schweitzer. Corrosion Resistance Tables, 4th ed., Vols. 1–3. New York: Marcel Dekker, 1995. PK Whitcraft. Corrosion of stainless steels. In: PA Schweitzer, ed. Corrosion Engineering Handbook, New York: Marcel Dekker, 1996. PA Schweitzer. Stainless steel. In: PA Schweitzer, ed. Corrosion and Corrosion Protection Handbook, 2nd ed. New York: Marcel Dekker, 1988. GT Murray. Introduction to Engineering Materials. New York: Marcel Dekker, 1993.


13- Martensitic Stainless Steels.pdf

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