Welding Electrode Flux, The Importance

Air Separation Plant

Welding electrode flux - The Importance By JGC Annamalai

1

2

3

4

5

6

Importance of Welding Electrode Flux (relevance to AWS A5.1)By JGC Annamalai 1. Chapters List: (1). Chapters List (2). Welding or Joining, Great Evidences (3). Developments in Welding (4). Classification of Welding Electrode (5). Selection of Welding Electrodes (6). Function and Importance of Flux on Electrode El ectrode Coating (7). Electrode Flux Ingredients and their proportions (8). Production of Welding Electrodes (9). Welding Electrode Requirements , Testing, Qualification, to meet AWS A5.1 (10). Tips on Welding Electrodes

Annexure List Annexure-(1), Welding Positions per ASME Sec IX Annexure-(2), AWS A5.1 recommended Welding Currents Annexure-(3), AWS Spec List List for Welding Consumables Annexure-(4), History, History, Chronology, Events & Mile-Stone Developments in Welding Annexure-(5), Recent Advances in Welding Annexure-(6), Welding Terms & Glossary

   1  .    1  .    g    P

Importance of Welding Electrode Flux (relevance to AWS A5.1) By JGC Annamalai 2. Great Evidences in the Development of Welding    1  .    2  .    g    P

2. Great Evidences in the Development of Welding    2  .    2    A  .    g    P

Importance of Welding Electrode Flux (relevance to AWS A5.1)

By JGC Annamalai

3. Welding & SMAW Electrodes - Developments    1 Earlier , Flux Coating Developments Developments  .    3  .    g (SMAW Electrodes are also called as Flux coated Electrodes Electrodes or Covered Electrodes or Coated Electrodes or MMA    P Welding Electrodes or Stick Welding Electrodes or Clay Electrodes ) Even now, we may see, in remote places and villages, welding welding is done using bare cables from transformers/ Generators to work location and also people using bare metal welding electrodes. Quality concious people always insist the use of coated electrodes as mandatory for normal and critical work. Stories: (1). Story related to Flux coating application-1: Initial Days, welders were using using bare metal welding electrodes, in open yards. Some rods fell on the wet ground during welding and the wet mud was coated on the electrode. When the welder used the dried, mud coated electrode(titania, lime ?), the welders found the arc was more stable and the weld was having little spatter and lesser porosity. Later, the welders investigated investigated and found, change is due to the mud deposit on the bare electrodes. Later, it lead to the flux coating.

(2). Story related to Flux coating application-2 : Bare metal rods were stacked on the open place. Due to rain, the rods were rusted. Welders started using the rusted(iron oxide coated) rods and the welders found the welding was more stable and the welding was having fewer spatters and lesser porosity. Later it lead to the flux coating. (3). Observations also showed that an improved weld could be made by (1). wrapping the rod in newspaper or (2). by welding adjacent to a pine board/stick placed close to and parallel with the weld being made. In these cases, some degree of shielding the arc from the atmosphere was being accomplished. These early observations led to the development of the coated electrode. However, Science believes or trusts only o nly recorded evidences and published reports. Between 1920 to 1927, A.O. Smith Corporation developed an electrode spirally wrapped with paper, soaked in sodium silicate, and then baked. This was the f irst of the cellulosic t ype electrodes. Smith Corporation established better method of coating by extruding over the core wire. This method allowed the addition of other flux ingredients to further improve or modify the weld metal. However, Lincoln Electric sued A.O. Smith on Electrode Patent and won. Quality level of present day electrodes, had reached a fairly satifactory stage. Now, we see, if we adhere to the following points, defects are under control and the weld defects are either nil or within acceptable limits. (1). The welding is done following the qualified Welding Procedure (2). Electrodes are stored and used following the Welding Electrode manufacturers' recommendations. (3). The base metal is cleaned and f ree of organic materials, paints, grease, oil, water, rust etc. The base metal is  free of surface defects, like porosity, laminations, the material is homogenious (spread of chemical elements uniformly). No welding is allowed, during high wind and rain. (4). Proper welding grooves/bevels are followed. The groove and gap shapes and dimensional tolerances are within limits. (5). Welders are skilled and should have eagerness to maintain continous quality level and know to use proper electrodes and know to skim the weld puddle and maintain constant arc length and control the bead size and shape and they are able to move the weld tip such that the slag is floating. Some of the well known Electrode Manufacturers are: (1). Lincoln Electric Company, USA and their affiliates (2). Oerlikon Welding Electrodes, Switzerland and their affiliates (3). D&H Secheron Welding Electrodes, (4). Philips Welding Electrodes, Netherlands and their affiliates (5). Kobe Steel Welding Electrodes Japan and their affiliates (6). Esab Welding Electrodes Sweeden and their affiliates (7). Hobart Welding Electrodes (8). Miller Electrodes Detailed Welding History or Timeline on Welding Developments are found in the attachment. Earliest Filler Metal Specifications Specifications (first issued as ASTM A233-40T and issued as AWS A5.1, from 1969, by AWS):  ASTM A 233-40T : The initial 1940 document and the three revisions within the next five years were prepared by a joint c ommittee of the American Society for Testing and Materials(ASTM)  and the American Welding Society(AWS). Society(AWS) . However, they were issued with only an ASTM specification designation. The 1948 revision was the first specification issued with the AWS designation appearing on the document. The 1969 revision was the first time that the document was issued without the ASTM designation.

Importance of Welding Electrode Flux (relevance to AWS A5.1)

By JGC Annamalai

4. SMAW Electrodes, Classification SMAW Electrodes : Other names are : Covered Electrodes, Stick Electrodes, MMA Electrodes (Material wise , they are classified: as Carbon Steel, Low Alloy Steel, Stainless Steel Electrodes etc.) (1). AWS A5.1 Electrode Classifications :

SMAW covered welding electrodes are identified with 4 digit letter with prefix "E". "E" represents Electrode. First 2 digits(like60 or 70) represents, the tensile strength, in 1000 psi 3rd digit(like 1,2,3,4; 1 for all position, 2, for Horizontal and flat position, 3 for Flat position,4 for Flat, Overhead, Horizontal, Vertical-Down) represents the welding position 4th digit(like 0,1 for Cellulose, 2,3,4,9 for Rutile, 5,6,8 for Lime/low hydrogen) represents the covering type(say, current type).

Tensile Strength, in 1000 psi Electrode EXX1X EXX2X EXX3X EXX4X -

      e         d       o       r        t       c       e         l         E

   1  .    4  .    g    P

Welding Positions All position(Flat, Hori, Vert, OH) Hori & Fl at on ly Flat position only Flat, OH, Hori, Vert.Down

Last digit indicates usability of the electrode, i.e. (1). type of current and (2). the type of covering. In some cases, both the third and fourth digits are significant.

E 60 1 0

Fourth Digit 0,1 2,3,4,9 5,6,8 7

Flux Type Cellulose Titania Lime/Low Hydrogen Iron Oxide

(2) First & second digit - Electrode Tensile Strength : Carbon Steel(Mild Steel) electrodes are made for low strength steel(say 60000 psi) or for high strength steel(say, 70000 psi) (3) Third digit - Welding Positions : There are four basic positions, like Flat, Horizontal, Vertical and Overhead. There are countless positions other than the basic positions. Flat Position - a position of welding in which the filler metal is posited from the upper side of the joint with the face of the weld horizontal. The welding end of the electrode is normally pointed downward. Horizontal Position  - A position of welding in which the weld is deposited up the upper side of a horizontal surface and against a vertical surface. The welding end of the electrode is normally positioned, at the side of a vertical wall Vertical Position – A position of welding in which the line of welding is in a vertical plane and deposited up on a vertical surface Overhead position – A position of welding in which the weld is deposited from the under side of the joint and the face of the weld is horizontal. (sample positions, as shown in the ASME Sec IX, is attached (a). for groove welds on plates & pipes and (b). for fillet welds on plates & structural shapes). Please check with ASME Sec IX or other Codes for the allowable variations in Positions. Per ASME Sec IX, welder qualified on pipe, with 6G position, qualifies the welder to weld on all positions of pipe, plates and structurals. So, most of the Companies used to have their welders qualified per ASME Sec IX, with pipe (4). Fourth Digit - Flux Type : SMAW- The electrode classification based on flux coverings are Cellulose or Wood Pulp type, Rutile or Titania type, Low Hydrogen or Lime tipe and Iron Oxide type Fourth Digit 0,1 2,3,4,9 5,6,8 7

Flux Type Cellulose Titania Lime/Low Hydrogen Iron Oxide

Typical for Electrodes(Length-Current-Weight): (5). Electric Power :      e  Diameter Length Current Current Pcs/ 5Kg Welding requires electric power to have arc and to melt the base       d       o  (mm) (mm) (A) (A) (approx)      r        t metals to join them. Often the electric power is either DC(from      c  (Position (Position      e         l       E F, H) V, OH) Generator or Rectifier, normally 20V to 70V) or AC(from 2.50 350 60-90 50-80 ≈258       0 Transformer, normally 50V to 100V).       1 3 .15 350 80-130 80-110 ≈157       0       6 ≈90 4.00 400 150-190 130-170 Mostly the Electrode Coating decides the DC or AC power. DC       E ≈80 5.00 450 150-190 130-170 power is most widely used as desired stable current is available ≈268 2 .50 350 60-100 6 0-90       3       1 ≈163 3 .15 350 80-150 80-110 and used by critical users like Power Plant, Chemical Plants etc.       0       6 ≈96 4.00 400 160-200 150-170       E AC power is used on low quality works like, structurals. ≈62 5.00 400 180-250 --2.50 350 60 -90 220 Similarly, Electric Coating decides the position of welding.       8       1 3.15 450 110 -140 143       0 To have consistent good quality, User Specifications always fix the       7 4.00 450 140 -180 73       E 5.00 450  180 -230 50 type of electrode / type of coating to be used on their plant

1 Most of the cases, the higher the electrode diameter, higher the deposition rate and faster the job completion. Larger diameter needs larger current and larger arc voltage. 2 Out of position welding(V or OH) should have smaller amount of slag for faster solidification to hold the liquid metal & smaller slag needs lower currents . Titania is used for V & OH positions 3 DC current is useful for welding with small diameter electrodes, low currents, out of position welding, welding thin material etc. DC used in SMAW welding with DCEP. DCEP give deeper penetration and DCEN give higher electrode melting rate.

   2  .    4  .    g    P

Welding Electric Volts Amps Common Power Transformer, AC 50 to 90V 125 to 700 Rectifier DC 20 to 90V 125 to 700 300 Amps Generator DC 20 to 90V 125 to 700 Spot Welding 12000 Amps and above(milli sec)

(6). Effect of Welding Electrode : Electric Current (Low-High); Travel Speed (Low-High) & Arc Too Long

Welding Currents: (Miller Electrode Recommendations)

Welding Currents: (AWS Recommendations)

   3  .    4  .    g    P

AWS Electrode Classification : A5.1

   4  .    4  .    g    P

(7). Comparison of Electrodes per AWS , ISO & Canadian(CSA) Standards : USA / AWS

Comparison of AWS/USA, ISO, Canadian Electrode Standards USA / AWS ISO-2560 Canadian ISO-2560

A5.1

A5.1M

A

B

A5.1

E6010

E4310

E35xC21

E4310

E4310

E6011

E4311

E35xC11

E4311

E6012

E4312

E35xR12

E6013

E4313

E6018

Canadian

A5.1M

A

B

E7014

E4914

E38xR32

E4914

E4914

E4311

E7015

E4915

E38xB22

E4915

E4915

E4312

E4312

E7016

E4916

E38xB12

E4916

E4916

E35xR12

E4313

E4313

E7016-1

E4916-1

—

E4916-1

E4318

—

E4318

E7018

E4918

E38xB32

E4918

E6019

E4319

E35xRA12

E4319

E7018-1

E4918-1

—

E4918-1

E6020

E4320

E35xA13

E4320

E7018M

E4918M

—

—

E6022

E4322

E35xA33

—

E4322

E7024

E4924

E38xRR4

E4924

E6027

E4327

E35xRA54

E4327

E4327

E7024-1

E4924-1

E38xRR4

E4924-1

E7027

E4927

E38xRA54

E4927

E4927

E7028

E4928

E38xB53

E4928

E4928

E7048

E4948

E38xB35

E4948

E4948

E4918b

E4924c

Importance of Welding Electrode Flux (relevance to AWS A5.1)  AWS Electrode Class

E6010 [E4310]

E6011 [E4311]

E6012 [E4312]

By JGC Annamalai

5. Selection of Welding Electrodes Coating - Arc - Slag

Weld Bead Shapes

Welding Positions

Electrode Applications

Electrical (Polarity, Amps & Voltage)

Electrodes are characterized by a deeply penetrating, forceful, spray type arc and readily removable, thin, friable slag which may not seem to completely cover the weld bead. The coverings are high in cellulose, usually exceeding 30 percent by weight. The other materials generally used in the covering include titanium dioxide, metallic deoxidizers such as ferromanganese, various types of magnesium or aluminum silicates, and liquid sodium silicate as a binder. Because of their covering composition, these electrodes are generally described as the high-cellulose sodium type.

Fillet welds usually have a relatively flat weld face and have a rather coarse, unevenly spaced ripple.

These electrodes are recommended for all welding positions, particularly on multiple pass applications in the vertical and overhead welding positions and where welds of good soundness are required. They frequently are selected for joining pipe and generally are capable of welding in the vertical position with either uphill or downhill progression.

The majority of applications for these electrodes is in joining carbon steel. However, they have been used to advantage on galvanized steel and on some low alloy steels. Typical applications include shipbuilding, buildings, bridges, storage tanks, piping, and pressure vessel fittings. Since the applications are so widespread, a discussion of each is impractical. Sizes larger than 3/16 in [5.0 mm] generally have limited use in other than flat or horizontal-fillet welding positions.

These electrodes have been    1  . designed for use with dcep    5  .    g (electrode positive). The    P maximum amperage that can generally be used with the larger sizes of these electrodes is limited in comparison to that for other classifications due to the high spatter loss that occurs with high amperage.

The electrodes duplicate the usability characteristics and mechanical properties of the E6010 [E4310] classification. Arc action, slag, and fillet weld appearance are similar to those of the E6010 [E4310] electrodes. The coverings are also high in cellulose and are described as the high-cellulose potassium type. In addition to the other ingredients normally found in E6010 [E4310] coverings, small quantities of calcium and potassium compounds usually are present.

 Fillet welds usually have a relatively flat weld face and have a rather coarse, unevenly spaced ripple.

Sizes larger than 3/16 in [5.0 mm] generally have limited use in other than flat or horizontal-fillet welding positions.

No rm all y, s im il ar t o E 601 0

E lec tr od es a re de si gne d t o b e used with ac current . Although also usable with dcep (electrode positive), a decrease in joint penetration will be noted when compared to the E6010 [E4310] electrodes.

Electrodes are characterized by low penetrating arc and dense slag, which completely covers the bead. This may result in incomplete root penetration in fillet welded joints. The coverings are high in titania, usually exceeding 35 percent by weight, and usually are referred to as the “titania” or “rutile” type. The coverings generally also contain small amounts of cellulose and ferromanganese, and various siliceous materials such as feldspar and clay with sodium silicate as a binder.  Also, small amounts of certain calcium compounds may be used to produce satisfactory arc characteristics on dcen (electrode negative).

Fillet welds tend to have a convex weld face with smooth even ripples in the horizontal welding position, and widely spaced rougher ripples in the vertical welding position which become smoother and more uniform as the size of the weld is increased. Ordinarily, a larger size fillet must be made in the vertical and overhead welding positions using E6012 [E4312] electrodes compared to welds with E6010 [E4310] and E6011 [E4311] electrodes of the same diameter.

The E6012 [E4312] electrodes are all-position electrodes and usually are suitable for welding in the vertical welding position with either the upward or downward progression. . The electrode size used for vertical and overhead position welding is frequently one size smaller than would be used with an E6010 [E4310] or E6011 [E4311] electrode

More often the larger sizes are used in the flat and horizontal welding positions rather than in the vertical and overhead welding positions. The larger sizes are often used for single pass, high-speed, high current fillet welds in the horizontal welding position. Their ease of handling, good fillet weld face, and ability to bridge wide root openings under conditions of poor fit, and to withstand high amperages make them very well suited to this type of work Weld metal from these electrodes is generally lower in ductility and may be higher in yield strength (1 ksi to 2 ksi [0.7 MPa to 1.4 MPa]) than weld metal from the same size of either the E6010 [E4310] or E6011 [E4311] electrodes

 AWS Electrode Class

E6013 [E4313]

E7014 [E4914]

5. Selection of Welding Electrodes Coating - Arc - Slag

Weld Bead Shapes

Electrodes contain rutile, cellulose, ferromanganese, potassium silicate as a binder, and other siliceous materials. The potassium compounds permit the electrodes to operate with ac at low amperages and low open-circuit voltages. A7.4.3 E6013 [E4313] electrodes are similar to the E6012 [E4312] electrodes in usability characteristics and bead appearance. . The usability characteristics of E6013 [ E4313] electrodes vary slightly from brand to brand. E6013 [E4313] electrodes, although very similar to the E6012 [E4312] electrodes, have distinct differences. Their flux covering makes slag removal easier and gives a smoother arc transfer than E6012 [E4312] electrodes. This is particularly the case for the small diameters 1/16 in, 5/64 in, and 3/32 in [1.6 m m, 2.0 mm, and 2.5 mm]. However, the larger diameters are used on many of the same applications as E6012 [E4312] electrodes and provide low penetrating arc. The smaller diameters provide a less penetrating arc than is obtained with E6012 [E4312] electrodes.  In addition, the weld metal is definitely freer of slag and oxide inclusions than E6012 [E4312] weld metal and exhibits better soundness Their flux covering makes slag removal easier and gives a smoother arc transfer than E6012 [E4312] electrodes.

The arc action tends to be quieter and the bead surface smoother with a finer ripple. With a more fluid slag, are used for horizontal fillet welds and other general purpose welding. These electrodes produce a flat fillet weld face rather than the convex weld face characteristic of E6012 [E4312] electrodes. They are also suitable for making groove welds because of their concave weld face and easily removable slag.

Electrode coverings are similar to those of E6012 [E4312] and E6013 [E4313] electrodes, but with the addition of iron powder for obtaining higher deposition efficiency. The covering thickness and the amount of iron powder in E7014 [E4914] are less than in E7024 [E4924] electrodes. The slag is easy to remove. In many cases, it removes itself.

Typical weld beads are smooth with fine ripples. Joint penetration is approximately the same as that obtained with E6012 [E4312] electrodes, which is advantageous when welding over a wide root opening due to poor fit up. The face of fillet welds tends to be flat to slightly convex.

Welding Positions

Electrode Applications

Electrical (Polarity, Amps & Voltage)

Recommended for sheet metal applications where their ability to weld satisfactorily in the vertical welding position with downward progression is an advantage. This is particularly the case for the small diameters 1/16 in, 5/64 in, and 3/32 in [1.6 mm, 2.0 mm, and 2.5 mm]. This permits satisfactory operation with lower open-circuit ac voltage. E6013 [E4313] electrodes were designed specifically for light sheet metal work.

E6013 [E4313] electrodes    2  . usually cannot withstand the high    5  . amperages that can be used with    g    P E6012 [E4312] electrodes in the flat and horizontal welding positions. Amperages in the vertical and overhead positions, however, are similar to those used with E6012 [E4312] electrodes.

The amount and character of the slag permit E7014 [E4914] electrodes to be used in all positions

The iron powder also permits the use of higher amperages than are used for E6012 [E4312] and E6013 [E4313] electrodes

 A7.6 Low-Hydrogen Electrodes Low Hydrogen  A7.6.1 Electrodes of the low-hydrogen classifications E6018 [E4318], E7015 [E4915], E7016 [E4916], E7018 Electrodes [E4918], E7018M [E4918M], E7028 [E4928], and E7048 [E4948]) are made with inorganic coverings that contain minimal moisture. The covering moisture test such as specified in AWS A4.4M, Standard Procedure for Determination of Moisture Content of Welding Fluxes and Welding Electrode Flux Coverings, converts hydrogenE6018 , bearing compounds in any form in the covering into water vapor that is collected and measured. The test thus assesses the potential hydrogen available from an electrode covering. All low-hydrogen E7015 , electrodes, in the as manufactured condition or after conditioning, are expected to meet a maximum covering moisture limit of 0.6 percent or less, as required in Table 10. E7016  A7.6.2 The relative potential of an electrode to contribute to diffusible hydrogen in the weld metal can be assessed more directly, but less conveniently, by the diffusible hydrogen test, as specified in Section E7018 , 18. The results of t his test, using electrodes in the as-manufactured condition or after conditioning, permit the addition of an optional supplemental diffusible hydrogen designator to the classification E7018M , designation according to Table 11 (see also A9.2 in this Annex). E7028 ,  A7.6.3 In order to maintain low-hydrogen electrodes with minimal moisture in their coverings, these electrodes and E7048 should be stored and handled with considerable care. Electrodes which have been exposed to humidity may absorb considerable moisture and their low-hydrogen character may be lost. Then conditioning can restore their low-hydrogen character (see Table A3.). Reconditioning is done at 350 °C for min. 1 hour. Electrodes can be reconditioned, max. 5 times.  A7.6.4 Low-hydrogen electrode coverings can be designed to resist moisture absorption for a considerable time in a humid environment. The absorbed moisture test (see Section 17) assesses this characteristic by determining the covering moisture after nine hours exposure to 80°F [27°C], 80 percent relative humidity air. If , after this exposure, the covering moisture does not exceed 0.4 percent, then the optional supplemental designator, “R,” may be added to the electrode classification designation, as specified in Table 10. See also A9.3 in this Annex.

 AWS Electrode Class

E7015 [E4915]

E7016 (E4916)

E7018 (E4918)

5. Selection of Welding Electrodes Coating - Arc - Slag The Arc of electrodes is moderately penetrating. The slag is heavy, friable, and easy to remove. Electrodes are commonly used for making small welds on thick base metal, since the welds are less susceptible to cracking. The shortest possible arc length should be maintained for best results with E7015 [ E4915] electrodes. This reduces the risk of porosity. The necessity for preheating is reduced; therefore, better welding conditions are provided.

Characteristics similar to E7015. It will work also on AC. Binder is Potassium silicate and contains Potassium salts.

E7048 [E4948]

Welding Positions

The weld face is convex, although Electrodes up to and a fillet weld face may be flat. including the 5/32 in [4.0 mm] size are used in all welding positions. Larger electrodes are used for groove welds in the flat welding position and fillet welds in the horizontal and flat welding positions.

Electrode Applications

 All similar to E7015

 All similar to E7015

E7018 [E4918] electrode coverings are similar to E7015 [E4915] coverings, except for the addition of a relatively high percentage of iron powder. The coverings on these electrodes are slightly thicker than those of the E7016 [E4916] electrodes. As is common with all lowhydrogen electrodes, a short arc length should be maintained at all times.

The electrodes are characterized by a smooth, quiet arc, very low spatter, and medium arc penetration. E7018 [E4918] electrodes can be used at high travel speeds.

The fillet welds made in the horizontal and flat welding positions have a slightly convex weld face, with a smooth and finely rippled surface.

The fillet welds made in the horizontal and flat welding positions have a slightly convex weld face, with a smooth and finely rippled surface. E6018 [E4318] electrodes possess operating and mechanical property characteristics similar to E7018 [E4918] except at a lower strength

E7018M [E4918M] electrodes are similar to E7018-1H4R [E4918-

Fillet welds made in the horizontal and flat welding positions have a slightly convex weld face, with a smooth and finely rippled surface.

inapplies equally well to the E7016 [E4916] electrodes. The electrodes are characterized by a smooth, quiet arc, very low spatter, and medium arc penetration. The E7028 [E4928] electrode coverings are much thicker. They make up approximately 50 percent of the weight of the electrodes. The iron content of E7028 [E4928] electrodes is higher (approximately 50 percent of the weight of the coverings). Consequently, on fillet welds in the horizontal position and groove welds in the flat welding position, E7028 [E4928] electrodes give a higher deposition rate than the E7018 [E4918] electrodes for a given size of electrode. Electrodes of the E7048 [E4948] classification have the same usability, composition, and design characteristics as E7018 [E4918] electrodes,

Electrical (Polarity, Amps & Voltage)

EThey are also used for welding high- Electrodes are low-hydrogen sulfur and enameling steels. Welds electrodes to be used with dcep made with E7015 [E4915] electrodes (electrode positive). The    3  .    5 on high-sulfur steels may produce a slag is chemically basic.  .    g very tight slag and a very rough or  Amperages for E7015 [E4915]   P irregular bead appearance in electrodes are higher than those comparison to welds with the same used with E6010 [E4310] electrodes in steels of normal sulfur electrodes of the same diameter. content.

 All similar to E7015

E7018M 1H4R] electrodes, except that the testing for mechanical properties and for classification is done on a groove weld that has a 60 degree [E4918M]

E7028 [E4928]

Weld Bead Shapes

 All similar to E7015

E7018 [E4918] low-hydrogen electrodes can be used with either ac or dcep.

E7018M [E4918M] is intended to be used with dcep type current in order to produce the optimum mechanical properties.

E7028 [E4928] electrodes On works, requiring, high rate of low are suitable for fillet welds hydrogen weld deposits . in the horizontal welding position and groove welds in the flat welding position only, whereas E7018 [E4918] electrodes are suitable for all positions. E7048 [E4948] electrodes are specifically designed for exceptionally good vertical welding with downward progression

 AWS Electrode Class

E6019 [E4319]

E6020 [E4320]

5. Selection of Welding Electrodes Coating - Arc - Slag

E6027 [E4327]

E7027 [E4927]

Welding Positions

E6019 [E4319] electrodes, although very similar  to E6013 and E6020 [E4313 and E4320] electrodes in their coverings, have distinct differences. E6019 [E4319] electrodes, with a rather fluid slag system, provide deeper arc penetration and produce weld metal that meets a 22-percent minimum elongation requirement, meets the Grade 1 radiographic standards, and has an average impact strength of 20 ft∙lbf [27J] when tested at 0°F [ –20°C].

When welding in the vertical welding position with upward progression, weaving should be limited to minimize undercut

While 3/16 in [5.0 mm] and smaller diameter electrodes can be used for all welding positions (except vertical welding position with downward progression), the use of larger diameter electrodes should be limited to the flat or horizontal fillet welding position..

E6020 [E4320] electrodes have a high iron oxide covering. They are characterized by a spray type arc.

The electrodes produce a smooth and flat, or slightly concave weld face and have an easily removable slag.

 A low viscosity slag limits their usability to horizontal fillets and flat welding positions.

The weld face tends to be more convex and less uniform, especially since the welding speeds are higher.

E6022 [E4322]

E7024 [E4924]

Weld Bead Shapes

E7024 [E4924] electrode coverings contain large amounts of iron The weld face is slightly convex to powder in combination with ingredients similar to those used in E6012 flat, with a very smooth surface and E6013 [E4312 and E4313] electrodes. The coverings on E7024 and a very fine ripple. [E4924] electrodes are very thick and usually amount to about 50 percent of the weight of the electrode, resulting in higher deposition efficiency. These electrodes are characterized by a smooth, quiet arc, very low spatter, and low arc penetration.

The E7024 [E4924] electrodes are well suited for making fillet welds in the flat or horizontal position

E6027 [E4327] electrode coverings contain large amounts of iron powder in combination with ingredients similar to those found in E6020 [E4320] electrodes. The coverings on E6027 [E4327] electrodes are also very thick and usually amount to about 50 percent of the weight of the electrode. E6027 [ E4327] electrodes have a spray-type arc. They will operate at high travel speeds. Arc penetration is medium. Spatter loss is very low. E6027 [E4327] electrodes produce a heavy slag which is honeycombed on the underside. The slag is friable and easily removed

Electrodes will produce a flat or slightly concave weld face on fillet welds in the horizontal position with either ac or dcen.

E7027 [E4927] electrodes have the same usability and design characteristics as E6027 [E4327] electrodes

Welds produced with E6027 [E4327] electrodes have a flat to slightly concave weld face with a smooth, fine, even ripple, and good wetting along the sides of the joint.

Electrode Applications

Electrical (Polarity, Amps & Voltage)    4  .    5  .    g    P

With arc penetration ranging from medium to deep (depending upon welding current), E6020 [E4320] electrodes are best suited for thicker base metal. Electrodes of the E6022 [E4322] classification are recommended for single- pass, high-speed, high-current welding of groove welds in the flat welding position, lap joints in the horizontal welding position, and fillet welds on sheet metal. They can be used with high travel Electrodes of these speeds. Electrodes designated as classifications can be operated E7024-1 [E4924-1] have the same on ac, dcep, or dcen. general usability characteristics as E7024 [E4924] electrodes. They are intended for use in situations requiring greater ductility and a lower transition temperature than normally is available from E7024 [E4924] electrodes. The weld metal may be slightly inferior in radiographic soundness to that from E6020 [E4320] electrodes.

These electrodes are intended for use in situations requiring slightly higher  tensile and yield strengths than are obtained with E6027 [E4327] electrodes

The E6027 [E4327] electrodes are designed for fillet or groove welds in the flat welding position with ac, dcep, or dcen. These electrodes are well suited for  thicker base metal.

Importance of Welding Electrode Flux (relevance to AWS A5.1)

By JGC Annamalai

6. Importance of Flux Covering on SMAW Electrodes Bare (or light coated) Electrodes : A solid metal electrode with no coating other than that incidental to the manucture of the electrode, or with a light coating. During the 1890's, arc welding was accomplished with bare metal electrodes    1

 . Covered(Shielded Arc) Electrode: A metal electrode which has a relatively thick covering material serving the dual    6  .    g purpose of stabilizing the arc and improving the properties of the weld metal. Around 1927, the covered electrodes   P were produced commercially, by extrusion process. With many variations in the formulations of the covering and the amount of covering on the mild steel core wire, many different classifications of electrodes are produced today. Covered Electrodes-  Development details are found in Chapter-3 and Timeline is found in the Annex-4 (a). Striking & establishing the arc were difficult. It stuck almost every time Bare Rod Welding: Difficulties (b). The rod turned red and started to melt above the arc (c). All oxidized, burned up, lot of spatters (d).Bead - it was the worst weld

Present Day Electrodes: have flux coatings/coverings. There are more than 100 flux ingredients, available in the market to make a particular type of electrode. Manufacturer has many electrodes with different Brand Name, each meeting AWS A5.1, with little changes in formulation. Formulations are secrets and they are protected by patents. Bare Electrode Welding :

Effects of Bare Electrode Welding

 c  O  (   r  M  a x   e  u  y   u  o i     s  g  t   l    s  e  e  s   t     u  s  n  p  a i   n r   o n  s   e r   d  t   i    n  o  e  s  H  a  , i    t    y  y  m  a  d  r   (    p n  o  d  g  o r   e  b  n  o  s  r  i   i   a  y   t    t    t   l   n  &   e n  d   e  t    s  h   p  s  e  s   a  y   t    e r   t    e r   a  )   .  c   s   t    p w l   i    t   i    s   t   h  w i   n  e  t   l    o  d   ,

Elec Power

Weld Bead Base Metal Weld Puddle

Power Discharging (corona) from rod surface to Base Metal (result-Eratic/unstable Arc)

Earlier days, bare electrodes were used to weld/to join metals. The welders experienced : (1). The arc was not stable and often wandering. The welded surface was uneven and often found with open porosity and lot of spatters. The welds were poor in appearance and welds were having low in ductility, low in fatique and impact resistance. (2). Oxygen (O2) and Nitrogen (N2) when in contact with molten metal caused brittle and porous welds, due to the formation of oxides, nitrodes. (3). Moisture entered the arc and turned into steam created porosity or split into Oxygen and Hydrogen and formed oxides and nascent hydrogen. (4). The melting rate was slow and the work completion is slow, due to thermal losses at electrode & at weld. (5). Welds were hard due to sudden cooling and cracking also observed on welds. (6). Hydrogen entered the weld arc and forms nascent hydrogen and these hydrogen atoms were able to travel inside the metal/weld and stay in the pockets/voids and started increasing the pressure and cracking the metal. (7). Iron and other alloy elements were burnt in the arc temperature and evaporated and often the critical metal composition was found appreciably reduced due to metal oxidation and evaporation. (8). Sulfur and phosphorous in the metal and rod or on the welding surface, would have formed their low melting sulfides and phosphates and compounds and created problems, during service.

For several years, cause for above problems were analysed and improvements were made and the result is the present coated electrodes. The atmospheric air/gases are the main cause for many of the problems and studies were made to protect the arc from atmospheric gases. Application of Flux(which forms shielding gases like CO2, CO) on bare electrode was one method of protecting the electrode arc. The following properties are also desired : easy cleanup, compatible weld strength, impact properties, unifor m bead quality and ability to minimize spatter etc. Electrode total quality should meet the AWS A5.1 and other such Standards

Happening at the Typical SMAW Arc Weld (present day) :

   2  .    6  .    g    P

Important Functions or Desired Properties of Flux or Ingredients on the Coated Electrodes: (1). Shielding of the Weld Metal - The most important function of a coating is to shield the weld metal from the oxygen and nitrogen of the air as it is being transferred across the arc, and while it is in the molten state. This shielding is necessary to ensure the weld metal will be sound, free of gas pockets, and have the right strength and ductility. At the high temperatures of the arc, nitrogen and oxygen combine readily with iron to form iron nitrides and iron oxides that, if present in the weld metal above certain minimum amounts, will cause brittleness and porosity. Nitrogen is the primary concern since it is difficult to control its effect once it has entered the deposit. Oxygen can be counteracted by the use of suitable deoxidizers. In order to avoid contamination from the air, the pool of molten metal must be protected or shielded by gases that exclude the surrounding atmosphere from the arc and the molten weld metal. This is accomplished by using gas-forming materials in the coating that break down during the welding operation and produce the gaseous shield. CO 2 is normally produced by the flux reaction and shields the weld. Popular Ingredients: Wood Pulp(cellulose), Titania(TiO 2 ), Lime stone(CaCO 3 )

(2). Concentration of the Arc Stream - Concentration or direction of the arc stream is attained by having a coating crater form at the tip of the electrodes. Use of the proper binders assures a good hard coating that will maintain a crater and give added penetration and better direction to the arc stream. Popular Ingredients: Potassium    3  .    6  . Silicate, Potassium Titanate, Mica    g    P (3). Formation of Slag for Fluxing and for protecting the Welded Beads  - The function of the slag is (1) to provide additional protection against atmospheric contamination, (2) to act as a cleaner and absorb impurities that are floated off and trapped by the slag, (3) to slow the cooling rate of the molten metal to allow the gases to escape. The slag also controls the contour, uniformity and general appearance of the weld. This is particularly true in fillet welds. Slag is a insulating material and prevents the heat to flow outside from weld, thus self annealing the weld and thus forming ductile weld material.  Popular Ingredients: Fledspar, Silica, Zircon, Titania (4). Stabilization of the Arc - A stabilized arc is one that starts easily, burns smoothly even at low amperages, and can be maintained using either a long or a short arc length.  Popular Ingredients: Alkali earth, Titania, Zircon, (5). Alloying Additions to Weld Metal - A variety of elements such as chromium, nickel, molybdenum, vanadium and copper can be added to the weld metal by including them in the coating composition. It is often necessary to add alloys to the coating to balance the expected loss of alloys of the core wire during the welding operation, due to volatization/vaporization and chemical reaction. Mild steel electrodes require small amounts of carbon, manganese and silicon in the deposit to give sound welds of the desired strength level. A portion of the carbon and manganese is derived from the core wire, but it is necessary to supplement it with ferromanganese and in some cases ferrosilicon additions in the coating. Popular Ingredients: Ferro-Silicon, Ferro-Manganese, (6). Welding in Difficult Position - It is the addition of certain ingredients, primarily titanium compounds, in the coating that makes it possible to weld out-of-position , vertical and overhead. Slag characteristics, primarily slag's surface tension and freezing point, determine to a large degree the ability of an electrode to be used for out-ofposition work(vertical & overhead positions).  Popular Ingredients: Titanium Compounds (TiO 2  . . . .) Common Flux Ingredients on SMAW Electrodes

Flux Name

 Alumina

Chemical Formula

   n    o    i    t    c    e    t    o    r    P    s    u    o    e    s    a    G

Functions of Flux / Ingredients

   n    o    i    t    a    d    i    x    o    e    D

   s    r    e    m    r    o    f    g    a    l    S

Al2O3

Cellulose

(C6H10O5)x

Clays

Al2O3.2SiO2.2H2O

Dolomite

MgO. CaO.(CO 2)2

Feldspar

K2O.Al 2O3.6SiO2

Ferro Alloys

FeMn, FeSi, FeTi

Flourspar

CaF2

Iron Oxides

FeO, Fe2O3, Fe3O4

Iron Powder

Fe

Lime

CaO

Limestone

CaCO 3

Pigments

X

X

X

X

X

X

X

X

X

X

X

X

X

X X

X X

X

X

X

X

X X X

X

   t    n    e    g    A    y    o    l    l    A

   g    n    i    t    a    o    C    f    o    r    o    l    o    C

X

X

X

   s    r    e    z    i    l    i    b    a    t    S    c    r    A

   s    t    n    e    g    A    )    n    i    g   o    s    s    r    n    u    e    i    p    t    d    p   r    n    i    i    l    x    B    S   E    (

X X

X

   l    o    r    t    n    o    C    y    t    i    s    o    c    s    i    V

X

X

X

X

X

X

---

X

Potassium Silicate

K2SiO3.nH2O

X

Rutile

TiO2

X

X

X

X

Silica

SiO2

X

X

X

X

Sodium Oxide

NaO

X

Sodium Silicate

Na2SiO3.nH2O

Talcs

3MgO4SiO2.4H2O

Zirconia

ZrO2

X

X

X X

X X

X

X

X

X

X X

X X

(7). Control of Weld Metal Soundness - Porosity or gas pockets in weld metal can be controlled to a large extent by the coating composition. It is the balance of certain ingredients in the coating that have a special effect on the    4  .  . presence of gas pockets in the weld metal. The proper balance of these is critical to the soundness that can be    6    g    P produced. Ferromanganese is probably the most common ingredient used to attain the correctly balanced formula, where the porosity is avoided. Popular Ingredients: Ferro alloys (8). Specific Mechanical Properties to the Weld Metal - Specific mechanical properties can be incorporated into the weld metal by means of the coating. High impact values for low temperature service, high ductility, and increases in yield and tensile properties can be attained by alloy additions to the coating. Popular Ingredients: Ferro-Nickel (9). Insulation of the Core Wire - The coating acts as an electrical insulator so that the core wire will not short-circuit when welding in deep grooves or narrow openings; coatings also serve as a protection/insulator to the welder when changing electrodes. Popular Ingredients: All. Pure metal powders are electrical conductive. Ferro-alloys are inert or neutral to electricity. At the welding temperatures, these ferro alloys will disintegrate and the metal will go as solid solution alloys in the weld. Major Grouping of Coatings / Ingredients (1). Shielding Gas Formers - Common gas forming materials used are the carbohydrates, hydrates, and carbonates. Examples would be cellulose (such as wood flock), the carbonates of calcium and magnesium, and chemically combined water as is found in clay and mica. These materials evolve carbon dioxide (CO 2), carbon monoxide (CO), and water vapor (H2O) at the high temperature of the welding arc. Free moisture is another gas-forming ingredient that is found particularly in cellulosic type electrodes and is a part of the formulation in amounts of 2%3%. It has a marked influence on the arc and is a necessary ingredient in the E6010 type electrode.

(2). Fluxes and Slag Formers - These ingredients are used primarily to give shape to the slag and impart such properties as slag viscosity, surface tension, and melting point. Silica and magnetite are materials of this type. Wood flour, wood pulp, refined cellulose, cotton linters, starch, sugar and other organic materials are used to provide a shielding of reducing gases. Silica, alumina, feldspar, clay, ironore, rutile, limestone, ilmenite, magnesite, white and blue asbestos, fluorspar, mica, manganese oxide and many other minerals, as well as some man-made materials such as potassium titanate and titanium dioxide are used as fluxes and slagging ingredients.

   5  .    6  .    g    P

(3). Arc Stabilizers - Air is not sufficiently conductive to maintain a stable arc, so it becomes necessary to add coating ingredients that will provide a conductive path for the flow of current. This is particularly true when welding with alternating current. Stabilizing materials are titanium compounds, potassium compounds, and calcium compounds.

(4). Alloying Elements - Alloying elements such as molybdenum, chromium, ni ckel, manganese and give specific mechanical properties to the weld metal.

(5). Silicon, Manganese, Aluminum and other elements are metals in ferro alloy forms, added to purify the weld(Oxygen killing elements).

(6). Plasticizers/Extruding Agent  - Coatings are often very granular or sandy, and in order to successfully extrude these coatings, it is necessary to add lubricating materials, plasticizers, to make the coating flow smoothly under pressure. Sodium and potassium carbonates, Mica and Talc are often used.

(7). Binders - Soluble silicates such as sodium Silicate (DC) and potassium silicates(AC & DC), are used in the electrode coating as binders. Functions of binders are to form a plastic mass of coating material capable of being extruded and baked. The final baked coating should be hard so that it will maintain a crater and have sufficient strength so that it will not spall, crack or chip, at the electrode operating temperatures and during handling time. Binders are also used to make coating non-flammable and avoid premature decomposition.    6  .    6  .    g    P

Killing of Steel in Steel Mill, is the process of removal of Oxygen from liquid metal Color of Coatings: in Steel laddle or furnace. During electrode flux mixing, this is done by adding Oxygen remover/oxidizers like Ferro-Managanes, Ferro-Silicon, Ferro-Aluminum and other metals, which will remove the Oxygen from weld puddle. Killing of oxygen in the weld metal, happens by the addition of ferro alloys (Ferro silicon, Ferro manganese, Ferro alloys) Welding rods are mostly from rimmed steel wires, AISI 1010, or equivalent. They are also called Hot Rods. MILD STEEL COVERED ELECTRODES & THEIR WELDING ATTRIBUTES Classificat Current Arc Penetrati Covering & Slag ion on

Iron Powder

EXX10 EXXX1 EXXX2 EXXX3 EXXX4 EXXX5 EXXX6

DCEP AC or DCEP AC or DCEN AC or DCEN or DCEP AC or DCEN or DCEP DCEP AC or DCEP

Digging Digging Medium Soft Soft Medium Medium

Deep Deep Medium Light Light Medium Medium

Cellulose Cellulose Titania - sodium Soft Light Titania - potassium Titania - iron powder Low hyd. - sodium Low hyd. - potassium

0- 10% 0 0-10% 0- 10% 25-40% 0 0

EXXX8 EXX20 EXX22 EXX24 EXX27 EXX28 EXX48

AC or DCEP AC or DCEN AC or DCEN or DCEP AC or DCEN or DCEP AC or DCEN or DCEP AC or DCEP AC or DCEP

Medium Medium Medium Soft Medium Medium Medium

Medium Medium Medium Light Medium Medium Medium

Low hyd. - iron powder Iron oxide - sodium Iron oxide - sodium Titania - iron powder Iron oxide- iron powder Low hyd. - iron powder Low hyd. - iron powder

25-40% 0 0 50% 50% 50% 25-40%

   e    t    v    h    e    i    g    v    i    i    t    t    e    i    a    g    s    e    w    o    P    N   n    e    e    o     d    d    d    e    o    o    s    r    r    t    t    a    c    c     b    e    e     l     l    e    E    E    g    t    t    a    n    n   t    n    e    e    r    r    r    r    e    c    u    u   r  .    C    C   e    g    p    t    t    n    c  ,    c    r    i    e    e    r    e    r    r    e    i    i     d    v    D   D    w   o    c    —   —   o   e    P    N   p    h    E    E    n   t    C    C   o    f    D   D   r    I    o

Electrodes, Larger Classification of Flux 1. Cellulosic Electrodes

   7  .    6  .    g    P electrodes

Coating consists of high cellulosic content more than 30% and TiO2 up to 20%. These are all position and produce deep penetration because of extra heat generated during burning of cellulosic materials. However, high spatter losses are associated with these electrodes. 2. Rutile Electrodes

Coating consists of TiO2 up to 45% and SiO2 around 20%. These electrodes are widely used for general work and are called general purpose electrodes. 3. Acidic Electrodes Coating consists of iron oxide more than 20%. Sometimes it may be up to 40%, other constituents may be TiO2 10% and CaCO3 10%. Such electrodes produce self detaching slag and smooth weld finish and are used normally in flat position. 4. Basic Electrodes Coating consist of CaCO3 around 40% and CaF2 15-20%. These electrodes normally require baking at temperature of approximately 250 ° C for 1-2 hrs or as per manufacturer's instructions. Such electrodes produce high quality weld deposits which has high resistance to cracking. This is because hydrogen is remo ved from weld metal by the action of fluorine i.e. forming HF acid as CaF2 generates fluorine on dissociation in the heat of arc.

Covered Electrode Standards: AWS A5.1, Carbon Steel Covered Electrodes : This chapter is giving detailed info on the flux coating on the Carbon Electrodes. AWS A5.5, Low Alloy Steel Covered Electrodes : The flux ingredients are mostly based on rutile and basic material. Cellulose type is listed in A5.5, but normally not used on low alloy steel welding, due to high percentage of water content. Lime coating is more common. AWS A5.4, Stainless Steel Covered Electrodes : The flux ingredients are mostly based on rutile and basic material. Cellulose type is not used on stainless steel welding, due to high percentage of water content. Lime coating is mor

Welding Electrode Heated up, due to Current Flow & Heat from Electrode Tip The graph, shows, the welding current, time and temperature of Electrodes. We see, the electrodes, were maximum heated, just after 2 minutes. Required-Electrode flux should withstand the heat and stay with the core rod, during the Temperature rise. Otherwise, the coating may spall.

Computer modeling, for studying & making an effective (AF max, 36%, PF-14, is considered the best in the group)

Compare: Welding Flux (Before Backing)

Welding Flux (After Backing)

(Typical)

   8  .    6  .    g    P

Importance of Welding Electrode Flux (related AWS A5.1) 6. Importance of Flux Covering on SMAW Electrodes

Electrode

Flux Covering

Formula

%

Function

 Cellulose

C6H10O5

35% Gas Former

Titania

TiO2

15% Slag Former -Arc Stabilizer

  E6010 Ferromanganese (Cellulose) Talc Sodium Silicate

Fe-Mn

5%

Deoxidizer -Alloying

Mg3Si4O10(OH)2

15% Slag Former

Na2SiO3

25% Binder -Fluxing Agent

H2O

 5%

Calcium Carbonate

CaCO3

5%

Cellulose

C6H10O5

10% Shielding Gas

Fledspar 

Complex Silicates

15% Slag Former 

TiO2

20% Slag Former

Moisture

Titania E6013 Talc (Titania) Zircon

Mg3Si4O10(OH)2 ZrSiO4

Ferromanganese

Fe-Mn

Potassium Silicate

K2SiO3

Moisture

H2O

 Calcium Carbonate CaCO3 Fluorspar  E7018 Ferromanganese  (Low Iron Powder Hydrogen) Potassium Silicate Moisture

CaF2 Fe-Mn

8%

Shielding Gas

Extrusion

14% Slag Former  6%

Alloying

20% Binder 2%

5%

Deoxidizer -Alloying

K2SiO3

15% Binder -Arc Stabilizer

Characteristics

Uses / Applications

Due to the high level of 40% H2 cellulose in the coating, they 40% CO + CO2 have excellent properties for 20% H2O out-of-position welding, but not good for horizontal welding. They are therefore mainly used for vertical-down welding on large pipes.

Mostly used in Cross Country pipelines and at  joints where joint penetration is essential.

These electrodes are very popular due to their good 40% H2 welding properties. The welding arc is stable and calm and is 40% CO + CO2 easy to reignite, the seams are finely rippled, and most of the slag comes off by itself. Rutile-coated electrodes have sufficient toughness properties, 20% H2O but are only suitable for out-of20% CO2 position welding to a limited extent (high-alloy).

Mostly used on Structures. Most of the middle and small size fabricaiton Shops use it. Very popular among welders as it gives quick start, stable arc, self peeling slag and user friendly . Generally RT is ok. These electrodes are the largest used among the electrodes.

The main advantages of basic electrodes are the outstanding toughness properties of the weld metal and its resistance to hot and cold cracks. Basiccoated electrodes have a coarse droplet material transfer, can be used to weld in all positions and have somewhat coarsely rippled seams. The slag can be relatively easily removed, but not as easily as with rutile-coated electrodes.

Used in critical areas where "Quality is First", Nuclear and other fossil power plants, Oil & Gas, Refinery, Chemical Plants, oil Platforms, Large Bridges, Large Cranes & earth movers etc.

20% Slag Former -Fluxing Agent 30% Deposition Stabilizer

H2O

Shielding

30% Gas Former -Fluxing Agent

Fe

By JGC Annamalai

Three Very Popular Electrodes

80% CO 20% CO2

 0.1%

Note: Titania Electrodes are also called Rutile Electrodes or Titanium Oxide Electrodes Low Hydrogen Electrodes are also ca lled Lime Stone Electrodes or Lime Electrodes or Basic Electrodes

   9  .    6  .    g    P

Flux/Ingredie Specific flux or Ingredients nts Group 1 Gas Formers Common gas forming materials used are the carbohydrates, hydrates, and carbonates. Examples would be cellulose (such as wood flock), the carbonates of calcium and magnesium, and chemically combined water as is found in clay and mica. 2 Fluxes & Slag Silica and Magnetite, Rutile , Formers Titania, Potassium titanate, Absestos, Alumina, Silica floor, iron oxide, Fluorspar etc. are materials of this type. 3 Arc Stabilizers Stabilizing materials are titanium compounds, potassium compounds, and calcium compounds. (potassium silicate, potassium oxalate, Zirconium carbonate, Lithium carbonate, Titania etc) 4 Alloying Elem Alloying elements such as ents molybdenum, chromium, nickel, manganese 5 De-oxidizers

De-oxidizers such as Ferrosilicon,

Major Function These materials evolve carbon dioxide (CO2), carbon monoxide (CO), and water vapor (H2O) at the high temperature of the

   0    1  .    6  .    g    P

welding arc. Free moisture is another gas-forming ingredient that is found particularly in cellulosic type electr odes and is a part of the formulation in amounts of 2%-3%. It has a marked influence on the arc and is a necessary ingredient in the E6010 type electrode.

These ingredients are used primarily to give body t o the slag and impart such properties as slag viscosity, surface tension, and melting point.

 Air is not sufficiently conductive to maintain a stable arc, so it becomes necessary to add coating ingredients that will provide a conductive path for the flow of current. This is particularly true when welding with alternating current.

These elements impart specific mechanical properties to the weld metal.

De-oxidizers remove oxygen from the weld pool.

Ferro-chromium, Ferromanganese, Ferro-Titanium are used. 6 Plasticizers

Sodium and potassium

Coatings are often very granular or sandy, and in order to

carbonates, Glycerine, China Clay, successfully extrude these coatings, it is necessary to add Talc, Mica are often used.

lubricating materials, plasticizers, to make the coating flow smoothly under pressure.

7 Binders

Soluble silicates such as sodium

Functions of binders are to form a plastic mass of coating material

and potassium silicates, are used

capable of being extruded and baked. The final baked coating

in the electrode coating as

should be hard so that it will maintain a crater and have sufficient

binders.

strength so that it will not spall, crack or chip. Binders are also used to make coating non-flammable and avoid premature decomposition.

Short List of Welding Electrode Flux-Ingredients

Popular Name

Formula

Main Function

Usage

1 Cellulose

C6H10O5

Gas Forming/ Shielding

Produces, CO 2. Frequently used on cellulose electrodes;

2 Limestone

CaCO3

Gas Forming/ Shielding

Produces CO & CO2, during welding; basic slag

3 Wood Flour

CnHnOn

Gas Forming/ Shielding

Produces, CO 2.

4 Bauxite

Al2O3

Slag Forming

Raises melting temperature and increases viscosity of

5 Dolomite

Magnesite, CaMg(CO 3)2

Slag Forming

Used as slag former in steel making, not in electrode

6 Feldspar

Alkali Type, KnNanAlSi3O8; Plagioclases-CaAl2Si2O8

   1    1  .    6  .    g    P

Slag Forming

7 Fluorspar

CaF2

Slag Forming

Decreases viscosity of molten slag

8 Iimenite

FeTiO3

Slag Forming

Impure Titanium Oxide

9 Magnetite

Iron Oxide, Fe 3O4

Slag Forming

Magnetic Iron Oxide

10 Periclase

Magnesium Oxide, MgO

Slag Forming

Raises melting temperature and increases viscosity of molten slag

11 Pyrolusite

Manganese dioxide, MnO 2

Slag Forming

12 Rutile

TiO2(10%Fe)

Slag Forming

Unrefined Titanium Oxide, Mainstay of Rutile Electrodes

13 Silica Flour

Cristobolite, SiO 2

Slag Forming

Strong acid slag former

14 Wollastonite

Calcium Silicate, CaSiO3

Slag Forming

15 Zirconia

Zirconium Oxide, ZrO2

Slag Forming

Occational

16 Lithium Carbonate Li2CO3

Arc Stabilizer

Occational

17 Potassium Oxalate K2C2O4

Arc Stabilizer

Occational Frequently used; purified Titanium Oxide

18 Titania

TiO2

Arc Stabilizer

19 Barium Fluoride

BaF2

Fluxing Agent

20 Cryolite

Na3AlF6

Fluxing Agent

Strong fluxing agent

21 Fluorspar

CaF2

Fluxing Agent

Strong fluxing agent

22 Lithium Chloride

LiCl

Fluxing Agent

Occational

23 Lithium Fluoride

LiF

Fluxing Agent

Very effective flux

24 Witherite

BaCO3

Fluxing Agent

Produces CO & CO2, during welding; basic slag

25 Chromium metal

Cr=100%

Alloying

Alloying

26 Elecro-manganese Mn=100%

Alloying

Most common alloying element

27 Electro-Nickel

Ni=100%

Alloying

Alloying

28 Ferromanganese

Mn=80%Mn+20%Fe

Alloying

Alloying

29 Ferroaluminum

85%Al+15%Fe

Deoxidizer

Strong deoxidizer

30 Ferrosilicon

50%Si+5%Fe

Deoxidizer

Silicon is deoxidizer & alloying element

31 Ferrotitanium

40%Ti+60%Fe

Deoxidizer

Strong deoxidizer & grain-refining agent

32 Zirconium Alloy

40%Zr+40%Si+20%Fe

Deoxidizer

Deoxidizer

33 Bentonite Clay

Montmorillonite, Al2Si4O10(OH)2 Slipping/ Extrusion Agent Used, water can be tolerated

34 Glycerin

Glycerol, C3H5(OH)3

Slipping/ Extrusion Agent Trihydric alcohol

35 Kaolin Clay

Kaolinite, Al2Si2O5(OH)

Slipping/ Extrusion Agent

36 Mica

Muscovite, KAl2(Si3Al)O10(OH)2

Slipping/ Extrusion Agent

37 Talc

Soapstone, Mg 3Si4O10(OH)2

Slipping/ Extrusion Agent

38 Asbestos

Cristotile, Mg3Si2O5(OH)4

Binders

39 Dextrin

Starch, C6H10O5

Binders

40 Gum Arabic

Acacia, CnOnHn

Binders

41 Potassium Silicate K2OnSiO2(OH)n

Binders

For AC use Most Frequently used

42 Sodium Silicate

Water Glass, Na2OnSiO2(OH)n

Binders

43 Sugar

Sugar, C n(OH)n

Binders

Improves, durability of the covering

Importance of Welding Electrode Flux (relevance to AWS A5.1)

By JGC Annamalai

7. Flux Coating (Typical %) on the Covered Electrodes - AWS-SMAW This chapter gives, % of Flux(Ingredients) on the SMAW Electrodes, relevance to AWS A5.1. AWS does not say on the method of    1 manufacture and on % Flux/Ingredients. 4 Typical Tables ar e attached. We notice, they differ widely.  .    7  . Table-1, gives % flux for 3 electrodes. They are the more popular electrodes in the Industry.    g    P Table-2, gives % of Flux for 5 Electrodes. Table-3, gives % of Flux for 8 Electrodes. Table-4, gives % Flux for 10 Electrodes. The present AWS A5.1 list has about18 Electrodes. Many of electrodes, are in the same group but with little variations, in key ingredients. Many of the New electrodes are Iron Oxide El ectrodes. There are over 100 electrodes made for AWS A5.1 by many manufacturers. There are also many patents. Several electrodes, in the group, will have same composition, but with little changes, in specific Ingredients. (It is similar to mummy making a Curry. Salt, Chilly/Pepper, Sour/lime are main additions to the curry. But, we will find the Curry taste differs and have different flavour, mummy to mummy. It is unique to each mummy). The sources for Tables 1 to 4 are different. We see the % ingredients differ, appreciably. AWS has specification control on the weld metal and not on the percentage.

Table-1 % Flux Coating on the Covered Electrodes - AWS-SMAW , (Typical-1, samples)-3 Electrodes

Table-2 % Flux Coating on the Covered Electrodes - AWS-SMAW , (Typical-2, samples)-5 Electrodes

Table-3 % Flux Coating on the Covered Electrodes - AWS-SMAW , (Typical-3, samples)-8 Electrodes

   2  .    7  .    g    P

Table-4

7. Flux Coating(%) on the Covered Electrodes - AWS -SMAW , (Typical-4, sample), 10 Electrodes

AWS Classifications (the latest AWS A5.1 has about 18 electrodes)

Chemicals present in the electrode flux (mostly minerals / Chemical Formula ores from earth)

Current Type Function, Primary Use

E6010 DCEP

E6011

E6012

E6013

AC or DCE P

AC or DCEN

AC, DCEP, or DCEN

E6020

E6027

AC or AC or DCEN DCEN

E7014 AC, DCEP, or DCEN

E7018

E7024

E7028

AC or DCEP

AC, DCEP, or DCEN

AC or DCEP

Titania, Iron Powder

 . Lime,    7  .    g Iron    P powder

Function, Cellulose Cellulose Titania Titania Iron Iron Oxide / Titania (iron Lime, Iron Powder Secondary Use (Sodium) (potassium) (Sodium) (Potassium) Oxide Iron Powder powder) (also called Low H2)

Calcium Carbonates CaCO3(Calcite) Shielding Gas Fluxing Agent C6H10O5 Cellulose Shielding Gas Fluxing Agent CaMg(CO3)2 Dolamite Shielding Gas Fluxing Agent  Al2O3 Alumina Slag Former FeO, FeO2, Fe3O4 Slag Former Iron Oxide Magnesium Oxide MgO Slag Former SiO2 Silica Slag Former Manganese di Oxide MnO, Mn2O3, Mn3O4 Slag Former Alloying KAlSi3O8 –NaAlSi3O8 –CaSlag Former Arc Stabilizer Fledspar TiO2 Titanium Oxide Slag Former Arc Stabilizer ZrSiO4 Zircon Slag Former Arc Stabilizer ZrO2 Zirconia Slag Former Arc Stabilizer Asbestos Complex Silicates Slag Former Extrusion Potassium Silicate K2SiO3 Arc Stabilizer Binder Potassium Titanate K2Ti O3 Arc Stabilizer Slag Former Ferro-manganese Alloying Deoxidiser Fe-Mn Iron Powder Decompotio Iron% Increase Fe Ferro-silicon Deoxidiser Fe-Si C3H8O3 Glycerin Extrusion Mica Arc Stabilizer Complex Silicates Extrusion Mg3Si4O10(OH)2 Talc Extrusion Binder Clay Slag Former Oxides of Si, Al, Mg Extrusion (Na2O)X·SiO2 Sodium Silicate Binder Fluxing Agent Total, %

21

1 15

3 4

2.7 12

2.6 2.6

4.9 1

36.4 10

   3

13.1 1 4.6

2.7 26.2

16.5

2.6

16

1.3 1.6

4

2.7 6.9

10 40

10.5

14.3 10.3 13.8

16 8.6

14 22

3.6 2.7

8.2 22

10 3

6.6 10.5

5.3

8 18.9 5.3

8

18.6 12.3 5.6

13.8 10.3

1.1 6.6 8.3

10

36.7 100

25 100

10.8 32.4

19.7 4.3

16.6

7

18

4.6 27.4 1.8

5.4 39 4.4

5 45

100

3.3 7 100

0.7

7.7 3.9

52.7 100

100

(a).AWS A5.1- Though AWS indicate major flux type/group , it does not specify what chemicals are to be used as flux and their %. The above Table contains 10 electrode types and it was prepared, for old AWS A5.1. Present AWS A5.1 contains, about 18 electrodes. Their electrode chemistry are expected same, for the group in the Table.

30 100

100

18 100

Titania Cellulose Low Hydrogen(Lime) E6010 E6012 E7014 E6018 E7018 E7048 Flux Groupings E6011 E6013 E7024 E7015 E7018M E7016 E7028 E6019

100

High Iron Oxide E6020 E7027 E6022 E6027

(b). Electrode Fabricator, through their licence and/or experience , establishes the optimum % of Flux coating for the Electrode Function. Typical sample is given above. % Composition depends on Purity.   :    s (c). Minerals : They are mostly Rocks/Ores.    e    t (1). Alumina - It is aluminum oxide , a chemical compound of aluminium and oxygen with the chemical formula Al2O3;    o

(2). Dolamite - Dolomite is an anhydrous carbonate mineral composed of calcium magnesium carbonate, ideally CaMg(CO3)2. (3). Fledspar-Feldspars (KAlSi3O8 – NaAlSi3O8 – CaAl2Si2O8) are a group of rock-forming tectosilicate minerals that make up about 41% of the Earth's continental crust by weight; (4). Mica-Mica is a group of sheet silicate minerals;

(7). Rutile or Titania or Titanium Oxide(TiO2) is a mineral composed primarily of titanium dioxide (TiO2)

(5). Silica-is sand(SiO2);

(8). Talc-a white, grey, or pale green soft mineral with a greasy feel, occurring as translucent masses or laminae and consisting of hydrated magnesium silicate.;

(6). Zirconia(ZrO2) is the ore and Zircon is Element.

Importance of Welding Electrode Flux (relevance to AWS A5.1)

By JGC Annamalai

8. Production of SMAW Electrodes

(1). Need for Quality : Due to poor quality of weld and many weld failures, there were many accidents and deaths and loss of properties in the initial period of welding, say, between 1920 to 1940. Standards were made to safe guard the    1  .    8 product quality. Now, users prefer , the electrodes are to be tested and accepted to Standards and Specification.  .    g    P Popular standard for Welding Electrodes, is AWS A5.1 (Specification for Carbon Steel Electrodes for Shielded Metal Arc Welding). Many users want testing and qualification for each batch of production. AWS A5.1 is periodically revised / updated to reflect, user requirements, the industry problems, technology advances etc. (2). Pre-Production Mild Steel or Carbon Steel covered electrodes, also commonly called coated electrodes, consist of only two major elements; the core wire or rod and the flux covering. The core wire is usually low carbon steel. It must contain only small amounts of aluminum and copper, and the sulfur and phosphorous levels must be kept very low so that undesirable brittleness in the weld metal is avoided. The raw material for the core wire is hot-rolled rod (commonly called "hot rod" or AISI-1010). It is received in large coils, cleaned, drawn down to the proper electrode diameter, straightened, and cut to the proper electrode length and coated. (3). Production of SMAW Electrodes The coating ingredients, (there are several hundreds), are carefully weighed, blended in a dry state, wet mixed, and compacted into a large cylinder that fits into the extrusion press. The coating is extruded over the cut core wires which are fed through the extrusion press at a rapid rate. The coating material is removed from the end of the electrode that is clamped into the electrode holder to assure electrical contact, and also from the welding end of the electrode to assure easy arc initiation. (4). Packing and Distribution: The electrodes are then stamped with the type number for easy identification before entering the ovens. Inside the oven, the electrodes go through a controlled bake cycle to insure the proper moisture content before packaging. Normal pack is 5 kg for easy handling. (5). Production of Covered Welding Ele ctrode (Some Key Operations) :

Coils from Steel Mills

Electrode Extrusion Plant

Electrode Baking/Drying Oven

Coils Descalled, drawn, re-wound

Coated Electrodes, from Extrusion Plant

Electrodes stacked for Packing

Flux ingredients, ready for Extrusion

Electrodes, stamped

Electrodes packed

8. Production of SMAW Electrodes

5 Production Flow Diagram :

   2  .    8  .    g    P

ROD

Hot rolled to electrode rod dia, about 3/16"

Cold Drawn to Diameter of Electrode Core

Strightened/ Surface Polished

Cut to Length

Protection Coating per Formula Weighed

Dry Mixed

Binder Added and Wet Mixed

Ingredients Slug Prepared

COATING

Uniform Concentric Coating Extruded on the Core Wire

Coating Removed from Contact and Holder End

Electrode Dried in Oven under Suitable Temperature

Electrode Stamped with AWS Identification

Tests, per AWS A5.1 Weld Test Assemblies: (1). Fig.1, Weld Pad Test Assembly for Chemical Analysis (2). Fig.2, Groove Weld for Mechanical Properties and weld metal soundness (3). Fig.3, Fillet Weld for the Usability of the Electrode (4). Fig.4, Groove Weld for Transverse Tensile and Longitudinal Bed Test for Welds made with E6022 Single -pass Electrode (5). Fig.5, Groove Weld for mechanical properties and Soundness of Weld metal made with E7018M electrode

Finished and Accepted Electrodes Packed for Shipment

1 AWS A5.1: Method of Manufacture. The electrodes classified according to this specification may be manufactured by any method that will produce electrodes that meet the requirements of this specification. 2 AWS A5.1 says : The core wire and covering shall be free of defects that would interfere with uniform deposition of the electrode. 3 Normal electrode core wire is rimmed steel, having 0.1% carbon(AISI 1010). 4 The raw material for the core wire is hotrolled rod (commonly called "hot rod")

AWS A5.1, there is no mention, on the size the OD of the coating. Requirements, testing etc are discussed in Chapter-9

Tests are required to meet the Electrode Standard and to meet user Spec. To have the Standard Name on package, like AWS A5.1, Electrode Testing, is mandatory. Normally, Tests are conducted for each flux mixing/batch Table 12

Electrodes, Standard Sizes and Lengths Core W ire Diameter,a

Lengths, a, b

 A5.1 (in)

A5.1Mc (mm)

A5.1 (in)

A5.1M (mm)

1/16

1.6

9

225

5/64

2.0

9 or 12

225 or 300

3/32

—

12 or 14

—

—

2.5

—

300 or 350

1/8

3.2

14

350

5/32

4.0

14 or 18

350 or 450

3/16

—

14 or 18

—

—

5.0

—

350 or 450

7/32

—

14 or 18 or 28

—

—

6.0

—

350 or 450 or 700

1/4

—

18 or 28

—

5/16

8.0

18 or 28

450 or 700

a. Lengths and sizes other than these shall be as agreed between purchaser and supplier. In all cases, end-gripped electrodes are standard. ofb. c. ISO 544 Welding consumables—Technical delivery conditions for welding filler maerials—Type of product, dimensions, tolerances and markings. See 20.2 for tolerances on diameter and length.

8. Production of SMAW Electrodes    3  .    8  .    g    P

Low Hydrogen Electrodes: Reconditioning is done at 350°C, for minimum 1 hour. Electrodes can be reconditioned, maximum 5 times. If the reconditioning exceeds 5 times, the electrodes should be discarded.

Importance of Welding Electrode Flux (relevance to AWS A5.1)

By JGC Annamalai

9. Electrode Requirements, Testing, Qualifications (1)

Acceptance of the Electrode, needs many Testing and approval. The following welded test assemblies/testing are to be completed: The sample for chemical analysis may be taken from the reduced section of the fractured tension test specimen    1  . 9.1 One or more of the following five weld test assemblies are    9  .    g required:    P

Electrodes other than low hydrogen electrodes shall be tested without conditioning(Conditioning is any preparation or procedure, such as baking the electrode, which the user would not normally prac tice). Low-hydrogen electrodes, if they have not been protected against moisture pickup in storage, shall be held at a temperature within the range 500°F to 800°F [260°C to 430°C] for a minimum of one hour prior to testing. If the results of any test fail to meet the requirement, that test shall be repeated twice. If one o r both specimen fail, the test is considered failed and not meeting the AWS A5.1. All tests shall be done or repeated, fo llowing proper prescribed procedures. Chemical Composition Requirements for Weld Metal (Table-7)  AWS Classification

UNS

Weight %

Combined Limit for 

 A5.1

A5.1M

Number

C

Mn

Si

P

S

Ni

Cr

Mo

V

E6010

E4310

W 06010

0.2

1.2

1

N.S.

N.S.

0.3

0.2

0.3

0.08

N.S.

E6011

E4311

W06011

0.2

1.2

1

N.S.

N.S.

0.3

0.2

0.3

0.08

N.S.

E6012

E4312

W06012

0.2

1.2

1

N.S.

N.S.

0.3

0.2

0.3

0.08

N.S.

E6013

E4313

W 06013

0.2

1.2

1

N.S.

N.S.

0.3

0.2

0.3

0.08

N.S.

W06019

0.2

1.2

1

N.S.

N.S.

0.3

0.2

0.3

0.08

N.S.

E6019

E4319

Mn+Ni+Cr+Mo+V

E6020

E4320

W06020

0.2

1.2

1

N.S.

N.S.

0.3

0.2

0.3

0.08

N.S.

E6027

E4327

W 06027

0.2

1.2

1

N.S.

N.S.

0.3

0.2

0.3

0.08

N.S.

E6018

E4318

W06018

0.03

0.6

0.4

0.025

0.015

0.3

0.2

0.3

0.08

N.S.

E7015

E4915

W07015

0.15

1.25

0.9

0.035

0.035

0.3

0.2

0.3

0.08

1.5

E7016

E4916

W07016

0.15

1.6

0.75

0.035

0.035

0.3

0.2

0.3

0.08

1.75

E7018

E4918

W07018

0.15

1.6

0.75

0.035

0.035

0.3

0.2

0.3

0.08

1.75

E7014

E4914

W07014

0.15

1.25

0.9

0.035

0.035

0.3

0.2

0.3

0.08

1.5

E7024

E4924

W07024

0.15

1.25

0.9

0.035

0.035

0.3

0.2

0.3

0.08

1.5

E7027

E4927

W07027

0.15

1.6

0.75

0.035

0.035

0.3

0.2

0.3

0.08

1.75

E7028

E4928

W07028

0.15

1.6

0.9

0.035

0.035

0.3

0.2

0.3

0.08

1.75

E7048

E4948

W07048

0.15

1.6/0.4

0.9

0.035

0.035

0.3

0.2

0.3

0.08

1.75

E7018M

E4918M

W07018

0.12

1.6/0.4

0.8

0.03

0.02

0.25

0.15

0.35

0.05

N. S.

 Notes: a). SAE/ASTM Unified Numbering System for Metals and Alloys. B). Single values are maximum. N. S. means Not Specified.

Moisture Testing: (Table-10) A5.1

A5.1 (Stamped )

E6018 E7015 E7016 E7018 E7028 E7048 E6018 E7015 E7016 E7018 E7028 E7048 E7018M

E6018 E7015 E7016 / E7016-1 E7018 / E7018-1 E7028 E7048 E6018R E7015R E7016R / E7016-1R E7018R / E7018-1R E7028R E7048R E7018M

AWS A5.1 (Table-11)

E7018M E7015 E6018 E7015 E7016 E7018 E7048

Unit-mL/100g of weld metal  As-Received or  As-Exposed Conditioned

H4

Electrodes, Standard Sizes and Lengths Core Wire Diameter,a

0.6

16 16 8 84

4

Not Specified (not accepted)

0.3

0.4

0.1

0.4

Diffusible Diffusible H2, Ave in Hydrogen mL/100g deposited Designator weld metal, max None 4 H16 H16 H8 H4H8

Table 12 Lengths, a, b

 A5.1 (in)

A5.1Mc (mm)

A5.1 (in)

A5.1M (mm)

1/16

1.6

9

225

5/64

2.0

9 or 12

225 or 300

3/32

—

12 or 14

—

—

2.5

—

300 or 350

1/8

3.2

14

350

5/32

4.0

14 or 18

350 or 450

3/16

—

14 or 18

—

—

5.0

—

350 or 450

7/32

—

14 or 18 or 28

—

—

6.0

—

350 or 450 or 700

1/4

—

18 or 28

—

5/16

8.0

18 or 28

450 or 700

a. Lengths and sizes other than these shall be as agreed between purchaser and supplier. b. In all cases, end-gripped electrodes are standard. c. ISO 544 Welding consumables—Technical delivery conditions for welding filler maerials—Type of product, dimensions, tolerances and markings. See 20.2 for tolerances on diameter and length.

9. Electrode Requirements, Testing, Qualifications (1) Covering Eccentricity(para-21) max

Grip End/Butt end for electrode size,5/32" [4.0 mm] & small, bare end shall be >1/2"[12 mm] & <1-1/4"[30 mm]

Eccenticity=(D1-D2)(100/D)

   2  .    9  .    g    P

for electrode size,<3/16" [5.0 mm] & larger, bare end shall be >3/4" [20 mm] & <1-1/2 in [40 mm] Electrode Stamping

min Rod(Core) dia=d Covering Normal Covering dia=D

E7018

Core+max.covering)=D1 Core +min.covering=D2 Max. Eccentricity : (1) 7 % in dia sizes 3/32 in [2.5 mm] and smaller (2) 5% in dia sizes 1/8 in [3.2 mm] and 5/32 in [4.0 mm] (3) 4% in dia sizes 3/16 in [5.0 mm] and larger

Arc End <2-1/2" [65 mm] of the grip 1/8 in [3.2 mm] or the diameter of end of the electrode the core wire, whichever is less Letters, Bold Block type of a size large enough to be legible. Ink is contrasting to the surface

The diameter of the core wire shall not vary more than ±0.002 in [0.05 mm] from the diameter specified. The length shall not vary more than ±1/4 in [10 mm] from that specified.

ASME QW-432 "F" Numbers QW "F" No 432.1 1 2 3 4 4 4 5 6 6 6 6 6 6 6 6

F Numbers grouping of e lectrodes and welding rods for qualification "F" Numbers are Filler Number ASME Specification No AWS Classification No SFA-5.1 and 5.5 EXX 20, EXX 24, EXX 27, EXX 28 SFA-5.1 and 5.5 EXX 12, EXX 13, EXX 14 SFA-5.1 and 5.5 EXX 10, EXX 11 SFA-5.1 and 5.5 EXX 15, EXX 16, EXX 18 SFA-5.4 Nom. Total Alloy 6 % or less EXX 15, EXX 16 SFA-5.4 Nom. Total Alloy more than 6 % EXX 15, EXX 16 SFA-5.4 Cr-Ni Electrode EXX 15, EXX 16 SFA-5.2 RGXX SFA-5.17 FXX-XXXX SFA-5.9 ERXX SFA-5.18 EXXS-X,EXXU-X SFA-5.20 EXXT-X SFA-5.22 EXXXT-X FXX-EXXX-X, FXX-ECXXX-X and SFA-5.23 FXX EXXX-XN, FXX-ECXXX-XN SFA-5.28 ER-XXX-X and E-XXX-X

ASME QW-442 "A" numbers classification of weld metal analysis for Procedure Qualification "A" NUMBERS ANALYSIS* "A" No QW Types of weld deposit C% Cr % Mo % Ni % Mn % Si % 442

1

Mild Steel

0.15

1.60

1.00

2

Carbon-Moly

0.15

0.50

0.40-0.65

1.60

1.00

3

Chrome (0.4 to 2 %)-Moly

0.15

1.40-2.00

0.40-0.65

1.60

1.00

4

Chrome (2 to 6 %)-Moly

0.15

2.00-6.00

0.40-1.50

1.60

2.00

5

Chrome (6 to 10.5 %)-Moly

0.15

6.00-10.50

0.40-1.50

1.20

2.00

6

Chrome-Martensitic

0.15

11.00-15.00

0.70

2.00

1.00

7

Chrome-Ferritic

0.15

11.00-30.00

1.00

1.00

3.00

8

Chromium-Nickel

0.15

14.50-30.00

4.00

7.50-15.00

2.50

1.00

9

Chromium-Nickel

0.30

25.00-30.00

4.00

15.00-37.00

2.50

1.00

10

Nickel to 4 %

0.15

0.55

0.80-4.00

1.70

1.00

11

Manganese-Moly

0.17

0.25-0.75

0.85

1.25-2.25

1.00

12

Nickel-Chrome-Moly

0.15

0.25-0.80

1.25-2.80

0.75-2.25

1.00

"A" Numbers are "Weld Analysis Number"

1.50

* Single values shown above are maximum.

Table-1

(For detailed info, please refer to the Original Spec, AWS A5.1).

AWS Classification

E6010 E6011 E6012 E6013 E6018 E6019 E6020 E6022 E6027 E7014 E7015 E7016 E7018 E7018M E7024 E7027 E7028 E7048

Type of Covering

High cellulose sodium High cellulose potassium High titania sodium High titania potassium Low-hydrogen potassium, iron po Iron oxide titania potassium High iron oxide High iron oxide High iron oxide, iron powder Iron powder, titania Low-hydrogen sodium Low-hydrogen potassium Low-hydrogen potassium, iron po Low-hydrogen iron powder Iron power, titania High iron oxide, iron powder Low-hydrogen potassium, iron po Low-hydrogen potassium, iron po

Welding Position

 Type of Current

Table-2

Table-3

Tensile Yield Elangatio Strength Strength n, (ksi) (0.2% %(min. Offset), length,4x

Impact Test A ve rag e

TEST REQUIREMENTS-2

Si ng le V al ue

F, V, OH, H DCEP 60 48 22 27 J @–30°C 20 J @–30°C F, V, OH, H AC OR DCEP 60 48 22 27 J @–30°C 20 J @–30°C F, V, OH, H AC OR DCEN 60 48 17 Not SpecifiedNot Specified F, V, OH, H AC, DCEP, OR DCEN 60 48 17 Not SpecifiedNot Specified 60 48 22 F, V, OH, H AC OR DCEP 27 J @–30°C 20 J @–30°C 60 48 22 27 J at –20°C]20 J at –20°C] F, V, OH, H AC, DCEP, OR DCEN 60 48 22 H-fillet/F AC OR DCEN/DCEP 1 Not Specified 60 Not Speci Not Spe Not SpecifiedNot Specified F, H-fillet AC OR DCEN 60 48 22 27 J @–30°C 20 J @–30°C H-fillet/F AC OR DCEN/DCEP 70 58 17 Not SpecifiedNot Specified F, V, OH, H AC, DCEP, OR DCEN 70 58 22 F, V, OH, H DCEP 27 J @–30°C 20 J @–30°C 70 58 22 27 J @–30°C 20 J @–30°C F, V, OH, H AC OR DCEP 70 58 22 F, V, OH, H AC OR DCEP 27 J @–30°C 20 J @–30°C 70 58 17e 27 J @–30°C 20 J @–30°C F, V, OH, H DCEP 70 58 22 Not SpecifiedNot Specified H-fillet, F AC, DCEP, OR DCEN 70 58 22 H-fillet/F AC OR DCEN/DCEP 27 J @–30°C 20 J @–30°C 70 58 22 27 J at –20°C]20 J at –20°C] H-fillet, F AC OR DCEP  Note f 53–72g 24 27 J @–30°C 20 J @–30°C F, O H, H, V-do AC OR DCEP

Table-4

Required Test for 4mm dia electrode, Other sizes refer to Table-4) Che mi cal RT & All-Weld Impact Analysis(Tab metal Tension Test (para le 7) Test, Para.11.0 14.0)

F F F F F F F NR F F F F F F F F F F

F F F F F F F F F F F F F V F F F F

F F NR NR F F NR NR F NR F F F V F F F F

Fillet Weld Moisture Test(para Test(par 15.0) a 16,17)

V&H V&H V&H V&H V&H V&H H, Fillet NR H, Fillet V&OH V&OH V&OH V&OH NR H, Fillet H, Fillet H, Fillet , Down&OH

NR    3  .  . NR    9    g NR    P NR REQD NR NR NR NR NR REQD REQD REQD REQD NR NR REQD REQD

Table-1

a). The abbreviations, the welding positions: F = Flat, H-fillets = Horizontal fillet, V = Vertical, progression upwards (for electrodes 3/16 in [5.0 mm] and under, except 5/32 in [4.0 mm] and under for classifications E6018 , E7014, E7015, E7016, E7018, E7018M, E7048). V-down = Vertical, progression downwards (for electrodes 3/16 in [5.0 mm] and under, except 5/32 in [4.0 mm] and under for classifications E6018, E7014, E7015, E7016, E7018, E7018M, E7048), OH = Overhead (for electrodes 3/16 in [5.0 mm] and under, except 5/32 in [4.0 mm] and under for classifications E6018, E7014, E7015, E7016, E7018, E7018M,E7048). b). The term “dcep” refers to direct current electrode positive (dc, reverse polarity). The term “dcen” refers to direct current electrode negative (dc, straight polarity). c). Electrodes with supplemental elongation, notch toughness, absorbed moisture and diffusible hydrogen requirements may be further identified (Tables 2, 3, 10, 11). d). Electrodes of the E6022 [E4322] classification are intended for single-pass welds only. Table-2

a). See Table 4 for sizes to be tested., b). Requirements are in the as-welded condition with aging as specified in 12.2. c.) Single values are minimum. d). A transverse tension test, as specified in 12.5 and a longitudinal guided bend test, as specified in Section 13 are required. e). Weld metal from electrodes identified as E7024-1 shall have elongation of 22% minimum. f). Tensile strength of this weld metal is a nominal 70 ksi [490 MPa]. g). For 3/32 in [2.4 mm] electrodes, the maximum yield strength shall be 77 ksi [530 MPa]. Table-3

a). Both the highest and lowest test values obtained shall be disregarded in computing the average. Two of these remaining three values shall exceed 20 ft∙lbf [27 J]. b). Electrodes with the following optional

supplemental designations shall meet the lower temperature impact requirements specified below: c). All five values obtained shall be used in computing the average. Four of the five values shall equal, or exceed, 50 ft∙lbf [67 J]. Table-4

a). NR means “not required.” The abbreviations, F, H-fillet, V-down, V, and OH are defined in Note a of Table 1. The terms “dcep” and “dcen,” are defined in Note b of Table 1.b). Standard electrode sizes not requiring

this specific test can be classified provided at least two other sizes of that classification have passed the tests required for them, or the size to be classified meets specification requirements by having been tested in accordance with Figures 1, 2, and 3 and Table 6. c). See Section 10. d). See Section 11. e). See Section 12. f). See Section 14. g). See Section 15. h). A radiographic test is not required for this classification. i) The moisture test given in Section 16 is the required test for moisture content of the covering. In Sections 17 and 18 are supplemental tests required only when their corresponding optional supplemental designators are to be used with the classification designators. j. An all-weld-metal tension test is not required for E6022 electrodes. Instead, a t ransverse tension test (see 12.5) and a longitudinal guided bend test (see Section 13) are required for classification of 5/32 in, 3/16 in, and 7/32 in [4.0 mm, 5.0 mm, and 6.0 mm] E6022 [] electrodes. k. When dcep and dcen are shown, only dcen need be tested. l. Electrodes longer than 18 in [450 mm] will require a double length test assembly in accordance with Note 1 of Figure 2, t o ensure uniformity of the entire electrode. m.Tests in Section 17, and in Section 18, are required for all sizes of E7018M . n. Electrodes identified as E7024-1 shall be impact tested (see Note b of Table 3).

Importance of Welding Electrode Flux (relevance to AWS A5.1) By JGC Annamalai 10. Welding Tips

(1). The % Ductility of Single pass weld on thick plate(outdoor, without preheat, in cold weather), may have lower values upto 50%, compared to normally welded with multipass welds.(%Elangation and %reduction in Area are measures for %Ductility)) (2). Hydrotesting or stressing the fresh weld should be avoided. Hydrogen found diffused in to the weld and lower the % ductility. Aging the completed weld around 100°C, for 48 hours, or aging in atmospheric temperature for longer    1  . time, was found to release the absorbed hydrogen and to increase the ductility to the desired value.    0    1  . (3). Tensile strength of completed weld with PWHT completed (620°C for one hour, per inch thick) will have 5000 psi,   g    P lower than from "As welded" specimen (4). Yield strength of PWHT completed weld(620°C for one hour per inch tk) will have 10000 psi, lower from "As welded" specimen. (5). Lower inter pass temperatures can be used, if the PWHT duration/dwell time, is appreciably increased (6). The only differences between the present E60XX and E70XX [E43XX and E49XX] classifications are the differences in chemical composition and mechanical properties of the weld metal. In many applications, electrodes of either of E60XX or E70XX [E43XX or E49XX] classifications may be used. Electrodes within a given classification have similar operating characteristics and mechanical properties (7). In steels with a carbon content over 0.25%, rapid cooling from the welding temperature may produce a hard, brittle zone adjacent to the weld. In general, carbon content should be low, 0.25%, for best weldability. Composition(%) (8). Welding with non-Low-hydrogen electrodes show crack , if the Element Preferred High(*) "preferred" limit is exceeded. But welding with low hydrogen Carbon 0.06 to 0.25 0.35 electrodes will generally tolerate a wider range of the elements (say, Manganese 0.35 to 0.8 1.4 beyond "High", in Table) Silicon 0.1 or less 0.3 (9). Low hydrogen electrodes are loaded to drying oven kept at 425°C for Sulfur 0.035 or less 0.05 one hour, before use. The electrodes should be kept in portable Phosphorus 0.03 or less 0.04 *-Additional care is required in welding of steels, ovens(holding oven), kept at 120°C to 150°C, till the electrodes are containing these amounts of the elements l isted consumed. Un-consumed(every-day) electrodes, should be returned to drying ovens kept at 425°C. (max 5 times, rebaking/drying oven). (10). Electrode should be started on a scratch plate (kept near the starting point) and the arc is moved to the groove/real weld location. (11). For each electrode, on the weld bead, starting point and finish point should be ground to remove the weld. Normally the starting point and finish point of the electrode, will not have suffcient shielding and may have porosity(open or buried). Further, due to the sudden cooling at the start & finish point, star cracks are observed at these points. It is common, 3/4" to 1" coated length at the butt end, is scrapped, as t he shielding is not guranteed or the welder cannot see the arc clearly, because of shading of the electrode holder. (12). The welding groove should be cleaned, to remove, rust, oil, grease, paint, chalk marks etc, to avoid carbon, sulfur, phosphorus elements, absorption to the weld. (13). Avoid welding, in high humidity(over 80%). No welding, allowed, without proper protection, during raining/wind. Weld/Bevel

   e (14).     l    e    v    v    o    e    o    B   r    G

θ

Area, m

Volume, for "L"

2

length, m

Steel Weight, Kg

3

t

=(t2)(tan(θ/2))(L)(7850)

=(t2)(tan(θ/2)) =(t2)(tan(θ/2))(L)

t(base metal thickness), w(fillet weld leg size),

w    t    d    e    l     l     l    i    e    F

L(length of weld length) are in meters.

=(1/2)(w2)

(15).

=(1/2)(w2)(L)

Cross Section Area, m

2

Volume,m

=(1/2)(w2)(L)(7850) 3

Core Weight, Kg

Electrode Length, L =(π/4)(d )

=(π/4)(d )(L)

=(π/4)(d )(L)(7850)

d(diameter of the electrode core wire),L(Core wire length of the electrode), are in meters While estimating the required number of electrodes, allowances are to be made for reinforcements, groove size, penetrations, spatters, dilutions, grinding losses, repairs, butt ends, alloying/extra Iron from Coating etc.

ASME Sec IX Annex-01

Welding Positions    1  .    1    A  .    g    P

Annex-02

Electrodes and their Recommended Current Ratings (AWS A5.1) E6018,

Electrode

A5.1

E6010, E6011

E6027, E6012

E6013

E6019

E6020

E6022

E7027

E7014

E7015,

E7018M,

E7024,

E7016

E7018

E7028

Diameter

E7048

   1  .    2    A  .    g    P

E4318 E4310,

E4327,

E4915,

E4918M,

E4924,

E4914

E4916

E4918

E4928

E4948

—

—

—

—

—

—

—

—

—

—

—

—

—

—

—

—

80 to 125

65 to 110

70 to 110

100 to 145

—

80 to 140

100 to 150

110 to 160

125 to 185

110 to 160

100 to 150

105 to 155

140 to 190

80 to 140

105 to 180

130 to 190

130 to 190

140 to 190

160 to 240

150 to 210

140 to 200

130 to 200

180 to 250

150 to 220

140 to 240

150 to 230

190 to 250

175 to 250

170 to 400

210 to 300

200 to 275

180 to 255

200 to 275

230 to 305

210 to 270

170 to 250

200 to 320

210 to 300

240 to 310

225 to 310

370 to 520

250 to 350

260 to 340

240 to 320

260 to 340

275 to 365

—

6.0

210 to 320

250 to 400

250 to 350

310 to 360

275 to 375

—

300 to 420

330 to 415

300 to 390

315 to 400

335 to 430

—

8.0

275 to 425

300 to 500

320 to 430

360 to 410

340 to 450

—

375 to 475

390 to 500

375 to 475

375 to 470

400 to 525

—

A5.1

A5.1M

(inch)

(mm)

E4311

E4312

E4313

E4319

E4320

E4322

E4927

1/16

1.6

—

20 to 40

20 to 40

—

—

—

5/64

2.0

—

25 to 60

25 to 60

35 to 55

—

3/32*

2.4*, 2.5*

40 to 80

35 to 85

45 to 90

50 to 90

1/8

3.2

75 to 125

80 to 140

80 to 130

5/32

4.0

110 to 170

110 to 190

3/16

5.0

140 to 215

7/32

5.6

1/4 5/16

A5.1M

*This diameter is not manufactured in the E7028 [E4828] classification.

When welding vertically upward & Overhead positions, currents near the lower limit of the range are generally used.

Annex. 3A Filler Metals, List of AWS Spec

Designation FMC

Filler Metal Comparison Charts

IFS

International Index of Welding Filler Metal Classifications

UGFM

User’s Guide to Filler Metals

A4.2M/A4.2

Procedures for Calibrating Magnetic Instruments to Measure the Delta Ferrite Content Austenitic and Duplex Ferritic-

   1  .    3    A  .    g    P

Austenitic Stainless Steel Weld Metal A4.3

Standard Methods for Determination of the Diffusible Hydrogen Content of Martensitic, Bainitic, and Ferritic Steel Weld Metal Produced by Arc Welding

A4.4M

Standard Procedures for Determination of Moisture Content of Welding Fluxes and Welding Electrode Flux Coverings

A5.01

Filler Metal Procurement Guidelines

A5.1/A5.1M

Specification for Carbon Steel Electrodes for Shielded Metal Arc Welding

A5.2

Specification for Carbon and Low Alloy Steel Rods for Oxyfuel Gas Welding

A5.3/A5.3M

Specification for Aluminum and Aluminum-Alloy Electrodes for Shielded Metal Arc Welding

A5.4

Specification for Stainless Steel Electrodes for Shielded Metal Arc Welding

A5.5

Specification for Low-Alloy Steel Electrodes for Shielded Metal Arc Welding

A5.6

Specification for Covered Copper and Copper Alloy Arc Welding Electrodes

A5.7

Specification for Copper and Copper Alloy Bare Welding Rods and Electrodes

A5.8

Specification for Filler Metals for Brazing and Braze Welding

A5.9

Specification for Bare Stainless Steel Welding Electrodes and Rods

A5.10/A5.10M Specification for Bare Aluminum and Aluminum-Alloy Welding Electrodes and Rods A5.11/A5.11M Specification for Nickel and Nickel-Alloy Welding Electrodes for Shielded Metal Arc Welding A5.12/A5.12M Specification for Tungsten and Tungsten-Alloy Electrodes for Arc Welding and Cutting A5.13

Specification for Surfacing Electrodes for Shielded metal Arc Welding

A5.14/A5.14M Specification for Nickel and Nickel-Alloy Bare Welding Electrodes and Rods A5.15

Specification for Welding Electrodes and Rods for Cast Iron

A5.16

Specification for Titanium and Titanium Alloy Welding Electrodes and Rods

A5.17/A5.17M Specification for Carbon Steel Electrodes and Fluxes for Submerged Arc Welding A5.18/A5.18M Specification for Carbon Steel Electrodes and Rods for Gas Shielded Arc Welding A5.19

Specification for Magnesium Alloy Welding Electrodes and Rods

A5.20

Specification for Carbon Steel Electrodes for Flux Cored Arc Welding

A5.21

Specification for Bare Electrodes and Rods for Surfacing

A5.22

Specification for Stainless Steel Electrodes for Flux Cored Arc Welding and Stainless Steel Flux Cored Rods for Gas Tungsten Arc Welding

A5.23/A5.23M Specification for Low-Alloy Steel Electrodes and Fluxes for Submerged Arc Welding A5.24

Specification for Zirconium and Zirconium Alloy Welding Electrodes and Rods

A5.25/A5.25M Specification for Carbon and Low-Alloy Steel Electrodes and Fluxes for Electroslag Welding A5.26/A5.26M Specification for Carbon and Low-Alloy Steel Electrodes for Electrogas Welding A5.28

Specification for Low-Alloy Steel Electrodes and Rods for Gas Shielded Arc Welding

A5.29

Specification for Low-Alloy Steel Electrodes for Flux Cored Arc Welding

A5.30

Specification for Consumable Inserts

A5.31

Specification for Fluxes for Brazing and Braze Welding

A5.32/A5.32M Specification for Welding Shielding Gases

Annex.3B

AWS Filler Metal Specifications by Material and Welding Process SMAW

GTAW

OFW

FCAW

SAW

ESW

E GW

Brazing

GMAW PAW Carbon Steel

A5.1

A5.18

A5.2

A5.20

A5.17

A5.25

A5.26

A5.8, A5.31

Low-Alloy Steel

A5.5

A5.28

A5.2

A5.29

A5.23

A5.25

A5.26

A5.8, A5.31

Stainless Steel

A5.4

A5.9,

A5.22

A5.9

A5.9

A5.9

A5.8, A5.31

A5.22 Cast Iron

A5.15

A5.15

A5.15

A5.15

A5.8, A5.31

Nickel Alloys

A5.11

A5.14

Aluminum Alloys

A5.3

A5.10

A5.8, A5.31

Copper Alloys

A5.6

A5.7

A5.8, A5.31

Titanium Alloys

A5.16

A5.8, A5.31

Zirconium Alloys

A5.24

A5.8, A5.31

Magnesium Alloys

A5.19

A5.8, A5.31

Tungsten Electrodes

A5.12

A5.14

A5.8, A5.31

A5.8, A5.31

Brazing Alloys and Fluxes Surfacing Alloys

A5.13

A5.21

Consumable Inserts

A5.30

Shielding Gases

A5.32

A5.21

A5.21

A5.32

A5.21

A5.32

   2  .    3    A  .    g    P

Importance of Welding Electrode Flux (relevance to AWS A5.1) Metalworking and Welding Timeline Year 4000 B.C.

By JGC Annamalai

Welding history is thought to begin in Egypt, starting in 4000 B.C. In general, civilizations started with copper and then progressed to bronze, silver, gold and iron. Discovery of Tin

3500 B.C.

   1  .    4    A  .    g    P

3000 - 2000 B.C. (1). Humans started working with bronze between 3000 and 2000 B.C. (2). During the bronze age small gold circular boxes were made by pressure welding lap joints together. (3). During this period, metal was shaped into jewelry, dining utensils and weapons. 3000 B.C.

(1). The Sumerians made swords that were produced using hard soldering. (2). Egyptians converted ore into sponge iron by heating with char coal. (3). Forge welding & brazing were known to Egyptians. (1). Cobalt used by Persians to color glass. (2). Ancient Example of Soldering. (3). Soldering in 2600 B.C. in Mesopotamia (Iraq) using metal that combined silver and gold.

2250 B.C.

1500 B.C.

Discovery of Mercury Instances of iron smelting (became more common in 1200 B.C.) Paintings discovered of brazing in tomb of Vizier Rekh-mi-re

1475 B.C. 1330 B.C. 1000 B.C. 900 to 850 B.C.

BC

589 B.C.

60 A.D.

310 A.D.

1000 - 1099 1375 1540

Egyptians used solder and a blow pipe, in 1330 B.C. for metal soldering. Golden Death Mask of Tut-Ench-Amun was the example Iron work started in 1000 B.C., bending the metal with the use of furnaces to produce swords and spearheads. (one type called the Catalan furnace) Gold boxes found in Ireland that were fabricated by forge welding The Egyptians followed with iron tool making. In this era iron grew slowly in popularity due to the familiarity and usefulness of bronze and copper. Iron weapons had been found and traced to the Babylonians (1). The Chinese during the Sui Dynasty developed the ability to turn wrought iron into steel. (2). The Japanese manufactured steel swards through a forging & welding process to pr oduce Samurai Swords. First time in welding history that gold brazing process was recorded by Pliny. He described how salts acted as a flux and how metal color determines brazing difficulty (color indicated the presence of oxides).

AD

(1). The Iron Pillar of Delhi was fabricated using iron billets(from meteoroid?). 25 feet high a nd weighs 6 tons, was forge welded. Now located at Kutub Minar, New Delhi. (2). Similar constructions were found in England, Scandinavia and Rome. The manuscript written by monk Theophilus had a description of mixing flux for silver brazing. He i ndicated the use of Sodium Chloride and Potassium Tarpate. Metals were 66 percent Silver-Copper. Discovery of the metal Zinc. Forge welding was in front and center. Blacksmiths pounded hot metal until it bonded. (1). Vannoccio Biringuccio released De la pirotechnia, which includes descriptions of the forging operation. (2). Renaissance craftsmen gained skills in the process, and the welding continued to grow during the following centuries.

1568

Benventuto Cellini, an Italian goldsmith, writes about brazing a silver/copper alloy using a soldering process

1599

First instance of the root of the word weld (originally well). 16th century: the first cast iron cannon was produced

1735

Evidence that platinum used by pre-Columbian Indians in Ecuador

1751

Pure nickel created by Axel F. Cronstedt, a Swedish chemist using German Ore.

1766

Hydrogen gas properties described by Henry Cavendish, an English chemist and physicist

1774

Discovery of oxygen

1776

Principles of oxygen cutting established by Lavoisier (French).

1800 1808-1827

Sir Humphrey Davy invented the electric arc(between 2 carbon electrodes, powered by a battery). Voltaic cell was discovered by Allesandro Volta(two different metals connected through a liquid tank). Sr. Humphrey Davy proves that aluminum existed. It wa s actually discovered by Friederich Wohler.

1828

Sponge platinum was welded together via cold-pressing and then hammering when hot.

Year 1836

Metalworking and Welding Timeline

1838

Acetylene was discovered in 1836 by Edmund Davy, but was not practical in welding until about 1900, when a suitable blowtorch was developed. Patent issued to Eugene Desbassayrs de Richemont for fusion welding

1839

Discovery of voltage generation with a homopolar device by Michael Faraday.

1841

Air-hydrogen blowpipe developed by German H. Rossier for soldering lead.

1846

1860

James Nasmyth while working for the British Admiralty discovered that repar welding surfaces with a slightly convex surface, the swarf and flux were squeezed out of the joint. This improved the strength of the joint. James Joule welded a bundle of wires by using an electric current and internal resistance to creat e heat. The resistance welding process was later perfected by Elihu Thomson. Wilde develops electric welding. Issued a process patent in 1865.

1862

Friederich Wohler used calcium carbide to create a cetylene gas

1876

Otto Bernz Company develops and sells a gasoline powered torch.

1881

The first documented use of fusion welding was in 1881 by Auguste de Meritens where he welded lead battery plates together with a carbon electrode. Welding took place in a box with a fixed electrode. The discovery of bare metal electrode welding was recognized in Europe.Slavianoff , a Russian, is credited by most historians for discovering the use of bare metal electrodes for arc welding . Two students of Augeste de Meritens, N. Benardos and S.Olszewski were issued a patent for a welding process that used carbon electrodes ( carbon arc welding ) and an electric power source. Elihu Thomson applied for 2 process patents for "Apparatus for Electric Welding." Invention of resistance welding (RW) with the first patents going to Elihu Thompson in 1885. He produced advances over the next 15 years. A patent was issued to Olszewski and Bernardos for carbon arc welding.

1856

1882 1885 1886 1888

   2  .    4    A  .    g    P

1889 - 1892

C.L. Coffin, pioneer of welding in the US; received patent for flash-butt welding, equipment and process. 2 patents for spot welding. Awarded first patent for metal electrodes & patent for bare metal electrode were welding process

1890

First known instance of a "torch" being used to break into a bank vault

1892

Commercial acetylene was produced in North Carolina by mixing water and calcium . Baldwin locomotive started to use Carbon Arc Welding to repair locomotives Combustion of acetylene and oxygen discovered by Henri LeChatelier. Argon discovered by Sir William Ramsey and Lord Reyleigh Kleinschmidt introduced the use of copper electrodes

1895 1897 1900 1901 1903 1906 1907 - 1908 1908 1909 1910 1911 1912

Foresche and Charles Picard developed the first oxy-acetylene welding torch . The process is used without the application of pressure. A. P. Strohmenger developed a coated metal electrode in Britain, for a more stable arc. Oxygen Lance  invented by Ernst Menne Thermite welding was invented; oxyfuel welding, well established. First machine for resistance butt welding after merger between Allgemeine Elektricitats-Gesellschaft (AEG) and Union-Elektricitats-Gesellschaft (UEG). First resistance spot welding machines  were produced. The LaGrange-Hobo resistance welding method was introduced. Oscar Kjellberg received a patent for the electrode coating process called Shielded Metal Arc Welding . The coating

helped to stabilize the arc, producing better welds than bare electrodes. Bernardos patented Electroslag Process which enabled the welder to weld thick plates in a single pass. The process he outlined was popular today. The Plasma Arc system using gas vortex to stabilize the arc was invented by Schonner while working in BASF. The Quasi-arc electrode was invented which was wrapped with an asbestos yarn by A.P. Strohmenger. Patent issued to Charles Hyde for brazing steel tubes. (1). First pipeline completed using oxyacetylene welding in Philadelphia. (2). Matters developed the plasma arc torch for heating a metal fusing furnace. Kjellberg, received a second patent for an electrode with a heavier coating of asbestos and a binder, sodium silicate. First welding machines, by Lincoln Electric. First auto body was welded by E.G. Budd using spot welding.

Year 1912

Metalworking and Welding Timeline Coated metal electrodes, with Clay or Lime, introduced by A.P. Strohmenger. Also awarded a patent for an electrode, coated with blue asbestos and sodium silicate binder. First time, an electrode produced a defect free weld.    3  .    4    A  .    g    P

1917

Gas shortage in England resulted in industry turning to electric arc welding for producing bombs and mines.

1919

1923

A.C. current welding was invented by C.J. Holslag, but not popular. Electric arc welding was the method used in the United States until 1920. Problems: the welding arc was unstable and the welds were not as strong as the base metal. At first, oxyfuel welding was the more popular welding method due to its portability and relatively low cost. President Wilson established the US Wartime Welding Committee of the Emergency Fleet Corporation. Establishment of the American Welding Society. Development of the paper coated electrode by Reuben Smith Founding of Institute of Welding Engineers

1924

First all welded buildings constructed by U.S. Boiler

1926 1927

P.K. Devers and H.M. Hobart test welding using helium a nd argon as a shielding gas. Naval research laboratory releases a paper on the use of X-Rays to test welds(RT ). A.O. Smith employee John J. Chyle patents first extruded all position rutile electrode later called the E6010 type.

1928

First welded railroad bridge created by Westinghouse to transport large generators.

1929

Lincoln Electric produces the Fleetwood 5 heavy coated electrode. American Welding Society establishes welding symbols. Patent issued to H.O. Hobart for arc welding, and the process that became GMAW (Gas Metal Arc Welding). Submerged arc welding developed by National Tube Company. All welded merchant ship  created. Release of stud welding, which soon became popular in shipbuilding and construction. Submerged arc weldin g(SAW) was invented the same year, and continues to be popular today. By 1930, arc welding was lower in cost than riveting and gas welding. Patent issued to Devers and Hobart for use of an electric arc within an inert gas atmosphere. Not well received by the welding industry because of high cost of gas (helium and argon) and unsuitable torch availability

1919 1919

1930

1931 1934 1935 1936 1937 1938

Welding of stainless steel (originally called shotwelding) by E .G. Budd Manufacturing. During the middle of the century, many new welding methods were invented. A timing controller for resistance welding is developed by Westinghouse (originally called an Ignitron) SAW (submerged arc welding) process using continuous wire feed and granulated flux was introduced. Process originally called Union Melt. British welding electrode standard established and solid extruded electrode released. First A.C. welding machine introduced by Miller Electric. The method had a high r ate of metal deposition and an absence of arc blow (the deflection of an electric arc from its normal path due to magnetic forces). The use of welding in structural steel buildings, was confirmed with BS 538 (metal arc welding in mild steel).

1939

Gravity welding introduced by K.K . Madsen. Germans weld ships to reduce weight and to enable the design of lar ger vessels Use of aluminum spot welding recognize as being useful in aviation

1940 - 1941

Gas tungsten arc welding (GTAW/TIG), was perfected in 1941. Invented by Russel Meredith. Developed by the Linde

1942

Company. Also called HELIARC or TIG. Pr eferred for welding Stainless Steel, Aluminum, agnesium. Fire cracker welding process patent given to George Hafergut.

1943

Gas metal arc welding (GMAW) was invented by Voldrich, Rieppel and Cary. Developed at Dow and Northrup

1945 1948 1949

Corporations , later l icensed to Linde Corporation. The sciaky company made, a three phase resistance welder. Development of an experimental hand-held MIG gun at the Battelle Memorial Institut e (Columbus, Ohio). Welding replaced riveting as the main method of assembly for ships with 5,171 vessels constructed through 1945. Gas metal arc welding followed in 1948 (GMAW , earlier called MIG and metal act ive gas (MAG)), allowing for fast welding of non-ferrous materials, but requiring expensive shielding gases. Westinghouse introduced Selenium Rectifier welding machine s.

Year 1950s

1951

Metalworking and Welding Timeline Shielded metal arc welding was developed during the 1950s, using a consumable electrode and a carbon dioxide atmosphere as a shielding gas, and it quickly became the most popular metal arc welding process. A.C. - D.C. r ectifier welding machines were introduced with built-in frequency for GTAW welding. Miller Electric developed the Miller controlled wave a.c. welder which was used for critical welds on missiles and aircraft. E lectric beam welding process launched by A.J. Stohr Print ed wiring board process wave soldering is introduced. E.O. Pa ton welding institute    4  . develops Electrostag Welding (ESW).    4  . Dry Rod Electrode oven  introduced to control moisture levels in electrodes.    g

   P

1954 - 1957

Flux-cored arc welding process  debuted (FCAW), in which the self-shielded wire electrode could be used with

automatic equipment, resulting in greatly increased welding speeds, and that same year, plasma arc welding was invented. Patented in 1957 by National Cylinder Gas Company. 1956

Friction welding process  introduced by Russia

1958-1959

Electroslag welding was released, and later, electro-gas welding, in 1961. Electron beam welding(1958), making deep and narrow welding possible through the concentrated heat source. Laser beam welding was useful in high-speed welding. Automated welding. These processes, were quite expensive

1960

due the high cost of the equipments, and this had limited their applications. Explosive welding was introduced. 1962

Sciaky welded Mercury Space capsule (outer and i nner titanium shell).

1963 1965 - 1967

The Varestraint Test determines the weldability. Wall-Colmony introduced the Fusewelder Torch . The fusewelder was an oxyacetylene torch that is frequently used hard surfacing CO2 Laser Welding and cutting (Gravity welding) started in the U.K.

1969

Russians weld in space  on SOYUZ-6.

1970

New soldering technologies were introduced to support electronic miniaturization: - vapor phase – infrared - hot gas

1991

Friction Stir welding introduced by TWI.

1999

The Edison Institute develops a method that leads to 300% increase in flux penetration into a weld.

2000

Introduction of magnetic pulse welding. An X-Ray is used to weld a metal/matrix composite. Use of diode laser welding expanded to metals such as stainless steel, titanium foil. Development of laser-arc-hybrid welding

2008 2013

Development of Gas Metal Arc Welding-Brazing, an process for welding steel used in autos. Process uses a filler metal comprised of silicon with a copper al loy. Low-carbon steel and aluminum welding using a lap joint and laser technology

Recent Advances in Welding (1980 to 2013)

1980 to 1990

Robotic welding, On-board computers, State-of-the-art electrodes, Exotic multiple gas mixes

1991

Friction Stir welding introduced by TWI.

1999

The Edison Institute develops a method that leads to 300% increase in flux penetration into a weld (Activating Flux Coating on the base metal surface to have electrical insulation).

2000

Introduction of magnetic pulse welding, An X-Ray is used to weld a metal/matrix composite, Use of diode laser welding expanded to metals such as stainless steel titanium foil.

2008

Development of laser-arc-hybrid welding

2013

Development of Gas Metal Arc Welding(GMAW)-Brazing, a process for welding steel used in autos. Process uses a filler metal (silicon - copper alloy ); Low-carbon steel and aluminum welding using a lap j oint ; laser technology.

Importance of Welding Electrode Flux (relevance to AWS A5.1) Annex-5

By JGC Annamalai

Recent (1980 to 2015) Advances in Welding

Advances were noticed in the following fields in Welding, during the period 1980 to 2015. 1980 to 1990 (a). Robotic welding, (b). On-board computers, (c). State-of-the-art electrodes, (d). Exoti c multiple gas mixes 1991 1999

Friction Stir welding introduced by TWI, Narrow Gap Welding Edison Institute develops a method that leads to 300% increase in (Activating) flux penetration i nto a weld.

2000

(a). Introduction of magnetic pulse welding, (b). An X-Ray is used to weld a metal/matrix composite, (c). Use of diode laser welding expanded to metals such as stainless steel, titanium foil etc.    1  .

2008

Development of laser-arc-hybrid welding

2013

Development of (a). Gas Metal Arc Welding(GMAW)-Brazing, a process for welding steel used in autos. Process uses a filler metal (silicon - copper alloy); (b). Low-carbon steel and aluminum welding using a lap  joint ; (c). laser technology.

   5    A  .    g    P

Many new materials were in R&D or already developed, but still problem of joining them : So, people are looking for (1). to have high strength, light weight material, joint is compatible to the base material (2). to withstand high corrosion (3). costwise cheaper (4). The present SMAW(MMA) and GTAW(TIG) welding process are considered, slow process to the Project Completion. Aim is to have welding process which give quicker joint completion, if possible, automation and faster Project completion. (5). Manufactering is simpler Many materials were already developed, to m eet the above. But the joining proc ess is still open. To speed up the SMAW and TIG process and to have joining process for the high strength & low weight material, these materials are in R&D. (1). Robotic welding, On-board computers, State-of-the-art electrodes, Exotic multiple gas mixes : (a). Already GMAW(MIG) process finds, automation everywhere, like Automobile and related manufacturing. SAW is also, almost automated. Start & stop needs manual controls. Electro-slag welding, Electron Beam welding, Laser Beam Welding are already automated. FCW (sister of SMAW) finds place in mechanized welding (b). On line Cameras and Computers are used to view the full metal deposit/welding in SMAW and other processes. (c). The chemistry of SMAW /Coated electrodes are already saturated. Each manufacturer have more than 100 electrodes types to suit varaity of situations of the user. (d). Exotic multiple gas mixes: Shielding and purging gases: Gases like Argon, Helium, Nitrogen, CO2 were used during welding for shielding the hot torches/flames and hot metals during welding. New inert gases are also being (2). GTAW(TIG) welding, Improvement using Activating Flux(Edison Welding Lab): The principle of the technique is that by applying a thin coating of the flux(as electrical insulator) to the surface of the material, the arc is constricted (focused) which increases the c urrent density at the anode root and the arc force acting on the weld pool. Comparison of normal GTAW and Flux Activated GTAW is shown here. Welding 6mm thick stainless steel, arc constriction significantly increases weld pool penetration producing a deep narrower weld compared with a wide, shallow weld bead with the conventional TIG process. Flux: TiO2, SiO2, Advantages: • Increases depth of penetration e.g. up to 12mm thick stainless steel can be welded in a single pass (3mm normal TIG) • Overcomes the problem of cast to cast variation (normal TIG produces a wide and shallow weld bead ) Disadvantages: • The weld beed has rougher surface appearance. After welding c leaning the weld and slag residues is necessary. • Max.thickness 12 mm can be welded in a single (with a mechanised technique). Thickness of greater than 6mm to 12 mm, the weld pool must be supported to prevent sagging of the weld bead.

• For thickness greater than 12mm, Activiated flux side welding with 7 mm thick is finished first and other side, normal GTAW can be used.

Annex-5 (3). Friction Stir welding :

Recent (1980 to 2015) Advances in Welding

 For butt welds, a rotating cylinder is pushed against the surface of the weld. This cylinder is attached to a pin which penetrates almost the entire depth of the weld. Rotation under pressure causes the development of frictional heat, which softens the workpiece material to the point where it can flow. At this point, the rotating tool is moved along the joint line, and the softened material in front of the tool is extruded between the pin of the tool and the cold material on one side of the pin. During this process, the interface is completely fragmented, and so a solid phase joint is

   2  .    5    A  .    g    P

Limitations: Initially, Friction stir welding method was developed, for Aluminum welding. So far, Stir welding is not used in production for any steel fabrication, but its potential advantages and rapid rate of technology development suggest that this will happen, soon. The tool experiences very high temperatures, often of the order of 1200°C, along with high rubbing stresses and high process stresses. The material is

 to survive these high temperature and high stressed conditions. Latest: Much research has been undertaken worldwide to develop the process for steels and other high strength corrosion resistant alloys, for example nickel and titanium alloys. (4). Magnetic Pulse WeldingMPW): Automobiles, aircraft and even bicycles are in need of light weight structures now. Works on  joining dissimilar high-strength light alloys are taken up at many R&D centers. One of the method of joining, is dissimilar metal welding by impact welding. Impact Welding is also called Magnetic Pulse Welding(MPW). This is very similar to Explosion Bonding/Welding, but here we join small size components. Only small energies are used. From, 1969, MPW has been successfully applied for tube to tube welding(mostly lap  joints). High electrical energies are stored in capacitor bank with typical values in the range of 20~100 kJ. In magnetic pulse welding, a very high energy current is discharged through a coil(for few micro seconds of electromagnetic pulse (<100µs)). The high and extremely fast current discharge creates electromagnetic forces between the coil and the outer tubular workpiece, which accelerates the latter towards the inner workpiece and makes an impact. A high-pressure collision is then created between the two surfaces of the metals to be joined. Under precisely controlled conditions a solid-state weld is the result. Advantage of using Magnetic Pulse Welding: • Allows welding of designs which with other processes are challenging or not possible. • High-speed pulse lasts from 10 to 100 µs, the only time limitation is loading and unloading and capacitor charge time. • High repeat. Suited to mass-production: typically 1 to 5 million welds per year. • Dissimilar metals welding is possible.Weld with no heat-affected zone.No need for filler materials. • Green process: no smoke, no radiation and no extraction equipment required. High quality clean interface. • Mechanical strength of the joint is stronger than that of the parent material. • High precision obtainable by adjustment of magnetic field. (5). Diode Laser High-power diode lasers are just beginning to make an impact on welding applications. They are physically smaller than other lasers, and their initial capital cost is not as large as it might be for traditional welding lasers because diode lasers have fewer system components. There are two types of Diode Lasers : (a). keyhole and (b). conduction welding. Both are autogenous—that is, no filler metal is added to the joint

Annex-5

Recent (1980 to 2015) Advances in Welding    3  .    5    A  .    g    P

Key Hole Welding: Keyhole, or deep-penetration, welding is probably the most common. In keyhole welding, the laser is focused to achieve a very high-power density—typically at least 1megawatt/cm2—at the workpiece.

At the center of the focused beam, where the laser power density is usually highest, the metal actually vaporizes, opening up a blind hole, or the keyhole, into the molten metal pool. Vapor pressure holds back the surrounding molten metal and keeps this hole open during the process. The metal vapor also radiates laser energy into the molten metal along the side of the keyhole, transferring energy through the entire depth of the keyhole and resulting in a weld with a deep aspect ratio. Keyhole mode welding is suitable for deep-penetration welds Conduction Welding: Conduction welding works over a relatively large linear power range. This means that the delivered power can be adjusted until the ideal conditions for the parti cular application are achieved. Considering, power co ntrol and shallow penetration, Conduction Mode Welding is most suitable for delicate, heat-sensitive parts and thin metals. (6). Laser-Arc-Hybrid Welding Hybrid Laser & Arc Welding combined, say, two welding processes are coupled in a single process zone. Lasers : lasers, CO 2 , Nd:YAG, diode or fibre laser are used. Arc Welding: gas metal arc welding, gas tungsten arc welding or plasma arc welding, or even combining two different laser Advantages: Increased travel speed (x2) or increased penetration (x1.3).  Improved tolerance to fit-up gap.  Ability to add filler material to improve weld metal  microstructure, joint quality and joint properties. Potentially improved energy coupling.  Increased heat input and reduced hardness.  Disadvantages: Two welding process are used. The operation is complex. Finding the trouble and Controlling is difficult. (7). Narrow Gap Welding: The term ‘narrow-gap’ welding is used to describe a group of process developments which have been specif ically designed to reduce weld metal volume in butt welds. The gap width also varies depending on the process and the equipment; from around 8 mm for GTAW up to 20 mm with SAW. Advantages: (1). Weld volume is less, so job will be completed in short time., (2). The weld volume is less so the heat input, defects, HAZ & distortion are less. Tool Modifications: Torch oscillation, wire oscillation, twist arc, Rotating Tip etc are some of the technique used to weld/fill the narrow gaps. Weld Head also needs some modification to suit the narrow gap.

Annex-5

Recent (1980 to 2015) Advances in Welding    4  .    5    A  .    g    P

(8). Laser Welding Technology: Laser(Light Amplification by Stimulated Emission of Radiation), suitable for welding include (1). pulsed neodymiumdoped yttrium aluminum garnet (Nd:YAG), (2). fiber, and (3). diode. The pulsed Nd:YAG laser has by far the largest install base with peak powers and pulse widths designed for micro welding. For example, 25-50 W pulsed Nd:YAG lasers are routinely used for seam welding 0.015-inch thick titanium cases for implantable devices. Fiber Lasers: More recently developed fiber lasers offer excellent flexibility in tailoring weld dimensions and the best penetration per watt performance, which enables high speed seam welding. A 300 W fiber laser can seam weld 0.01-inch thick airbag detonator casings at 2 inches per second, while a 20 W pulsed fiber laser can produce a 0.001-inch diameter spot welds in 0.001-inch thick foil. The architecture of the fiber laser is scalable, with laser powers available at multi kilowatt levels used for penetration welding applications up to and beyond 0.25-inch The diode laser is a well-established laser technology that has been used for many plastic welding applications, notably in the automotive industry fo r welding the rear light housing. Welding o f plastics with lasers is a current growth area, particularly with the development of laser-friendly plastics and lasers that can weld visually clear plastics. More recently, the diode laser has beco me available at multi-kilowatt levels suited t o metal welding.

o

Laser is used to cut as well as to weld, with little modification to the head. Aluminum, B eryllium Copper, CS, Copper, Nickel Alloys, Nitinol, Phosphor Bronze, SS, Titanium etc. are welded using Lasers. Mostly used in mass production  jobs, by automobiles, PCB, Plastics. Not suitable for field works. Max.material thickness welded-20mm.

Annex-5

Recent (1980 to 2015) Advances in Welding

(9). Plasma Welding: th

Plasma  is said to be 4  state of matter (after Solid-Liquid-Gas). Plasma is a gaseous mixture of positive ions,

   5  .    5    A  .    g    P

electrons and neutral gas molecules, moving at high velocities (approx. speed of sound, (say at 20°C,343 m/sec or 1235 km/hr) and a temperature approx. 28,000 °C or higher. Plasma Arc Welding is the welding process utilizing heat generated by a constricted arc struck between a tungsten non-consumable electrode and the work piece (transferred arc process) or water cooled constricting nozzle (nontransferred arc process). Transferred arc process produces plasma jet of high energy density and may be used for high speed welding and cutting of Ceramics, steels, Aluminum alloys, Copper alloys, Titanium alloys, Nickel alloys. Non-transferred arc process produces plasma of relatively low energy density. It is used for welding of various metals and for plasma spraying (coating). Since the work piece in non-transferred plasma, arc welding is not a part of electric circuit, the plasma arc torch may move from one work piece to other without extinguishing the arc. Advantages of Plasma Arc Welding (PAW): (a). Requires less operator skill due to good tolerance of arc to misalignments; (b). High welding rate; (c). High penetrating capability (keyhole effect); Disadvantages of Plasma Arc Welding (PAW): (a). Expensive equipment; (b). High distortions and wide welds as a result of high heat input (in transferred arc

Annex-6

Welding Terms & Glossary

Abrasive – Slag used for cleaning or surface roughening.

Page-A6.1

Active Flux – Submerged-arc welding flux from which the amount of elements deposited in the weld metal is dependent upon welding conditions, primarily arc voltage. Adhesive Bonding – Surfaces, solidifies to produce an adhesive bond. Air Carbon Arc Cutting – An arc cutting process in which metals to be cut are melted by the heat of carbon arc and the molten metal is removed by a blast of air. All-Weld-Metal Test Specimen  – A test specimen with the reduction section composed wholly of weld metal. Alloying  – Adding a metal or alloy to another metal or alloy. Alternating Current (AC) – Electric current that reverses direction periodically, usually many times per second. Annealed Condition – A metal or alloy that has been heated and then cooled to remove internal stresses and to make the material less brittle. Arc Blow – The deflection of an electric arc from its normal path because of magnetic forces. Arc Cutting – A group of thermal cutting processes that severs or removes metal by melting with the heat of an arc between an electrode and the work piece. Arc Force – The axial force developed by an arc plasma. Arc Gouging – An arc cutting procedure used to form a bevel or groove. Arc Length – The distance from the tip of the electrode or wire to the work piece. Arc Time – The time during which an arc is maintained. Arc Voltage – The voltage across the welding arc. Arc Welding – A group of welding processes which produces coalescence of metals by heating them with an arc, with or without the application of pressure and with or without the use of filler metal. Arc Welding Deposition Efficiency (%)  – The ratio of the weight of filler metal deposited to the weight of filler metal melted. Arc Welding Electrode – A part of the welding system through which current is conducted that ends at the arc. As-Welded  – The condition of the weld metal, after completion of welding, and prior to any subsequent thermal or mechanical treatment. Atomic Hydrogen Welding – An arc welding process which produces coalescence of metals by heating them with an electric arc maintained between two metal electrodes in an atmosphere of hydrogen. Austenitic – Composed mainly of gamma iron with carbon in solid solution. Autogenous Weld – A fusion weld made without the addition of filler metal. Automatic  – The control of a process with equipment that requires little or no observation of the welding and no manual adjustment of the equipment controls. Back Gouging – The removal of weld metal and base metal from the other side of a partially welded joint to assure complete penetration upon subsequent welding from that side. Backfire – The momentary recession of the flame into the welding or cutting tip followed by reappearance or complete extinction of the flame. Backhand Welding – A welding technique where the welding torch or gun is directed opposite to the direction of welding. Backing – A material (base metal, weld metal, or granular material) placed at the root of a weld joint f or the purpose of supporting molten weld metal. Backing Gas  – A shielding gas used on the underside of a weld bead to protect it from atmospheric contamination.

Backing Ring – Backing in the form of a ring, generally used in the welding of pipe.

Page-A6.2 Back-Step Sequence – A longitudinal sequence in which the weld bead increments are deposited in the direction opposite to the progress of welding the joint. Base Metal (material)  – The metal (material) to be welded, brazed, soldered, or cut. See also substrate. Bend Radius – Radius of curvature on a bend specimen or bent area of a formed part. Measured on the inside of a bend. Bevel – An angled edge preparation. Blanking – Process of cutting material to size for more manageable processing. Braze Welding – A method of welding by using a filler metal, having a liquidus above 840 °F (450 °C) and below the solidus of the base metals. Brazing – A group of welding processes which produces coalescence of materials by heating them to a suitable temperature and by using a filler metal, having a liquidus above 840 °F (450 °C) and below the solidus of the base materials. The filler metal is distributed between the closely fitted surfaces of the joint by capillary attraction. Burr – A rough ridge, edge, protuberance, or area left on metal after cutting, drilling, punching, or stamping. Buttering – A form of surfacing in which one or more layers of weld metal are deposited (for example, a high alloy weld deposit on steel base metal which is to be welded to a dissimilar base metal). The buttering provides a suitable transition weld deposit for subsequent completion of the butt weld on the groove face of one member. Butt Joint – A joint between two members lying in the same plane. Camber  – Deviation from edge straightness, usually the greatest deviation of side edge from a straight line. Cap Pass – The final pass of a weld joint. Carrier Gas  – In thermal spraying, the gas used to carry powdered materials from the powder feeder or hopper to the gun. Capillary Action  – The action by which the liquid surface is elevated or depressed where it contacts a solid because the liquid molecules are attracted to one another and to the solid molecules. Cladding – A thin (> 0.04") layer of material applied to the base material to improve corrosion or wear resistance of the part. Clad Metal  – A composite metal containing two or three layers that have been welded together. The welding may have been accomplished by roll welding, arc welding, casting, heavy chemical deposition, or heavy electroplating. Coalescence  – The uniting of many materials into one body. Coherent  – Moving in unison. Cold Lap  – Incomplete fusion or overlap. Collimate  – To render parallels to a certain line or direction. Complete Fusion  – Fusion that has occurred over the entire base material surfaces intended for welding, and between all layer and passes. Complete Joint Penetration  – Joint penetration in which the weld metal completely fills the groove and is fused to the base metal throughout its total thickness. Constant Current Power Source – An arc welding power source with a volt-ampere output characteristic that produces a small welding current change from a large arc voltage change. Constant Voltage Power Source  – An arc welding power source with a volt-ampere output characteristic that produces a large welding current change from a small arc voltage change. Contact Tube – A system component that transfers current from the torch gun to a continuous electrode. Contact Resistance – The resistance in ohms between the contacts o f a relay, switch, or other device when the contacts are touching each other. Contact Tube – A device which transfers current to a continuous electrode

Covered Electrode – A filler metal electrode used in shielded metal-arc welding, consisting of a metal-wire core with a flux covering. Page-A6.3 Crater  – In arc welding, a depression on the surface of a weld bead. Crater Crack  – A crack in the crater of a weld bead. Cryogenic  – Refers to low temperatures, usually -200 o (-130 o) or below. Cutting Attachment – A device for converting an oxy-fuel gas-welding torch into an oxy-fuel cutting torch. Cylinder  – A portable container used for transportation and storage of a compressed gas. Defect  – A discontinuity or discontinuities that by nature or accumulated effect (for example, total crack length) renders a part or product unable to meet minimum applicable acceptance standards or specifications. Density – The ratio of the weight of a substance per unit volume; e.g. mass of a solid, liquid, or gas per unit volume at a specific temperature. Deposited Metal – Filler metal that has been added during welding, brazing or soldering. Deposition Efficiency  – In arc welding, the ratio of the weight of deposited metal to the net weight of filler metal consumed, exclusive of stubs. Deposition Rate  – The weight of material deposited in a unit of time. It is usually expressed as pounds/hour (lb/h) or kilograms per hour (kg/h). Depth of Fusion – The distance that fusion extends into the base metal or previous pass from the surface melted during welding. Dew Point – The temperature and pressure at which the liquefaction of a vapor begins. Usually applied to condensation of moisture from the water vapor in the atmosphere. Dilution – The change in chemical composition of a welding filler material caused by the admixture of the base material or previously deposited weld material in the deposited weld bead. It is normally measured by the percentage of base material or previously deposited weld material in the weld bead. Direct Current – Electric current that flows in one direction. Direct Current Electrode Negative (DCEN)  – The arrangement of direct current arc welding leads in where the electrode is the negative pole and work-piece is the positive pole of the welding arc. Direct Current Electrode Positive (DCEP)  – The arrangement of direct current arc welding leads in where the electrode is the positive pole and work-piece is the negative pole of the welding arc. Duty Cycle – The percentage of time during a time period that a power source can be operated at rated output without overheating. Dynamic Load – A force exerted by a moving body on a resistance member, usually in a relatively short time interval. Electrode Extension – The length of electrode extending beyond the end of the contact tube. Electrode Holder – A welding process that produces coalescence of metals with the heat obtained from a concentrated beam composed primarily of high velocity electrons Electron Beam Welding  – A welding process producing coalescence of metals with molten slag which melts the filler metal and the surfaces of the work to be welded. The molten weld pool is shielded by the slag, which moves along the full cross section of the joint as welding progresses. Electroslag Welding  – A welding process producing coalescence of metals with molten slag which melts the filler metal and the surfaces of the work to be welded. The molten weld pool is shielded by the slag, which moves along the full cross section of the joint as welding progresses. Eutectoid Composition – A mixture of phases whose composition are determined by the eutectoid point in the solid region of an equilibrium diagram and whose constituents are formed by eutectoid reaction. Facing Surface – The surfaces of materials in contact with each other and joined or about to be joined together. Filler Material  – The material to be added in making a welded, brazed, or soldered joint.

Fillet Weld  – A weld of approximately triangular cross section that joins two surfaces approximately at right angles to each other in a lap joint, T-joint, or corner joint. Page-A6.4 Filter Plate  – A transparent plate tinted in varying darkness for use in goggles, helmets and hand shields to protect workers from harmful ultraviolet, infrared and visible radiation. Flame Spraying  – A thermal spraying process using an oxy-fuel gas flame as the source of heat for melting the coating material. Flammable Range  – The range over which a gas at normal temperature (NTP) forms a flammable mixture with air. Flat Welding Position  – A welding position where the weld axis is approximately horizontal and the weld face lies in an approximately horizontal plane. Flashback – A recession of the flame into or back of the mixing chamber of the torch. Flashback Arrestor  – A device to limit damage from a flashback by preventing the propagation of the flame front beyond the point at which the arrestor is installed. Flashing – The violent expulsion of small metal particles due to arcing during flash butt welding. Flux – Material used to prevent, dissolve, or fac ilitate removal of oxides and other undesirable surface substances. Flux Cored Arc Welding (FCAW)  – An arc welding process that produces coalescence of metals by means of tubular electrode. Shielding gas may or may not be used. Friction Welding  – A solid welding process which produces coalescence of material by the heat obtained from a mechanically induced sliding motion between rubbing surfaces. The work parts are held together under pressure. Friction Stir Welding  – A solid-state welding process, which produces co alescence of material by the heat obtained from a mechanically induced rotating motion between tightly butted surfaces. The work parts are held together under pressure. Forehand Welding  – A welding technique where the welding torches or gun is pointed toward the direction of welding. Fusion  – The melting together of filler metal and base metal (substrate), or of base metal only, which results in coalescence. Gas Metal Arc Welding (GMAW)  – An arc welding process where the arc is between a continuous filler metal electrode and the weld pool. Shielding from an externally supplied gas source is required. Gas Tungsten Arc Welding (GTAW) – An arc welding process where the arc is between a tungsten electrode (nonconsumable) and the weld pool. The process is used with an externally supplied shielding gas. Gas Welding  – Welding with the heat from an oxy-fuel flame, with or without the addition of f iller metal or pressure. Globular-Spray Transition Current  – In GMAW/Spray Transfer, the value at which the electrode metal transfer changes from globular to spray mode as welding current increases for any given electrode diameter. Globular Transfer  – In arc welding, a type of metal transfer in which molten filler metal i s transferred across the arc in large droplets. Groove Weld  – A weld made in a groove between two members. Examples: single V, single U, single J, double bevel etc. Hard-Facing – Surfacing applied to a workplace to reduce wear. Heat-Affected Zone – That section of the base metal, generally adjacent to the weld zone, whose mechanical properties or microstructure, have been altered by the heat of welding. Hermetically Sealed  – Airtight. Heterogenous  – A mixture of phases such as: liquid-vapor or solid-liquid-vapor. Hot Crack  – A crack formed at temperatures near the completion of weld solidification. Hot Pass  – In pipe welding, the second pass which goes over the root pass. Inclined Position  – In pipe welding, the pipe axis angles 45 degrees to the horizontal position and remains stationary. Incomplete Fusion  – A weld discontinuity where fusion did not occur between weld metal and the joint or adjoining weld beads.

Incomplete Joint Penetration  – A condition in a groove weld where weld metal does not extend through the joint thickness. Page-A6.5 Inert Gas  – A gas that normally does not combine chemically with the base metal or filler metal. Intergranular Penetration – The penetration of filler metal along the grain boundaries of a base metal. Interpass Temperature – In a multi-pass weld, the temperature of the weld area between passes. Ionization Potential  – The voltage required to ionize (add or remove an electron) a material. Joint  – The junction of members or the edges of members that are to be joined or have been joined. Kerf  – The width of the cut produced during a cutting process. Keyhole  – A technique of welding in which a concentrated heat source penetrates completely through a work-piece forming a hole at the leading edge of the molten weld metal. As the heat source progresses, the molten metal fills in behind the hole to form the weld bead. Lap Joint – A joint between two overlapping m embers in parallel planes. Laser  – A device that provides a concentrated coherent light beam. Laser is an acronym for Light Amplification by Stimulated Emission of Radiation. Laser Beam Cutting – A process that severs material with the heat from a concentrated coherent beam impinging upon the work-piece. Laser Beam Welding  – A process that fuses material with the heat from a concentrated coherent beam impinging upon the members to be joined. Leg of Fillet Weld  – The distance from the root of the joint to the toe of the fillet weld. Liquidus – The lowest temperature at which a metal or an alloy is completely liquid. Mandrel  – A metal bar serving as a core around which other metals are cast, forged, or extruded, forming a true, center hole. Manifold  – A multiple header for interconnection of gas or fluid sources with distribution points. Martensitic  – An interstitial, super-saturated solid solution of carbon in iron, having a body-centered tetragonal lattice. Manual Welding – A welding process where the torch or electrode holder is manipulated by hand. MIG  – See Gas Metal Arc Welding (GMAW). Mechanical Bond – The adherence of a thermal-spray deposit to a roughened surface by particle interlocking. Mechanized Welding  – Welding with equipment where manual adjustment of controls is required in response to variations in the welding process. The torch or electrode holder is held by a mechanical device. Melting Range – The temperature range between solidus and liquidus. Melt-Through  – Visible reinforcement produced on the opposite side of a welded joint from one side. Metal Cored Arc Welding  – A tubular electrode process where the hollow configuration contains alloying materials. Metal Cored Electrode  – A composite tubular electrode consisting of a metal sheath and a core of various powdered materials, producing no more than slag islands on the face of the weld bead. External shielding is required. Molecular Weight  – The sum of the atomic weights of all the constituent atoms in the molecule of an element or compound. Monochromatic  – The color of a surface that radiates light, containing an extremely small range of w avelengths. Neutral Flame  – An oxy-fuel gas flame that is neither oxidizing nor reducing. Open-Circuit Voltage  – The voltage between the output terminals of the welding machine when no current is flowing in the welding circuit. Orifice Gas  – In plasma arc welding and cutting, the gas that is directed into the torch to surround the electrode. It becomes ionized in the arc to form the plasma and issues from the orifice in the torch nozzle as the plasma jet.

Oxidizing Flame  – An oxy-fuel gas flame having an oxidizing effect (excess oxygen).

Page-A6.6

Peening  – The mechanical working of metals using impact blows. Pilot Arc – A low current continuous arc between the electrode and the constricting nozzle of a plasma torch that ionizes the gas and facilitates the start of the welding arc. Plasma  – A gas that has been heated to at least partially ionized condition, enabling it to conduct an electric current. Plasma Arc Cutting (PAC) – An arc cutting process using a constricted arc to remove the molten metal with a highvelocity jet of ionized gas from the constricting orifice. Plasma Arc Welding (PAW) – An arc welding process that uses a constricted arc between a non-consumable electrode and the weld pool (transferred arc) or between the electrode and the constricting nozzle (non-transferred arc). Shielding is obtained from the ionized gas issuing from the torch. Plasma Spraying (PSP)  – A thermal spraying process in which a non-transferred arc is used to create an arc plasma for melting and propelling the surfacing material to the substrate. Plug Weld  – A circular weld made through a hole in one member of a lap or T joint. Porosity  – A hole-like discontinuity formed by gas entrapment during solidification. Post-Heating  – The application of heat to an assembly after welding, brazing, soldering, thermal spraying, or cutting operation. Postweld Heat Treatment  – Any heat treatment subsequent to welding. Preform  – The initial press of a powder metal that forms a compact. Preheating  – The application of heat to the base metal immediately before welding, brazing, so ldering, thermal spraying, or cutting. Preheat Temperature  – The temperature of the base metal immediately before welding is started. Procedure Qualification  – Demonstration that a fabricating process, such as welding, made by a specific procedure can meet given standards. Pull Gun Technique – Same as backhand welding. Pulsed Power Welding  – Any arc welding method in which the power is cyclically programmed to pulse so that the effective but short duration values of a parameter can be utilized. Such short duration values are significantly different from the average value of the parameter. Equivalent terms are pulsed voltage or pulsed current welding. Pulsed Spray Welding – An arc welding process variation in which the current is pulsed to achieve spray metal transfer at average currents equal to or less than the globular to spray transition current. Push Angle – The travel angle where the electrode is pointing in the direction of travel. Rake Angle  – Slope of a shear knife from end to end. Reducing Flame – A gas flame that has a reducing effect, due to the presence of excess fuel. Reinforcement  – Weld metal, at the face or root, in excess of the metal necessary to fill the joint. Residual Stress  – Stress remaining in a structure or member, as a result of thermal and/or mechanical treatment. Stress arises in fusion welding primarily because the melted material contracts on cooling from the solidus to room temperature. Reverse Polarity  – The arrangement of direct current arc welding leads with the work as the negative pole and the electrode as the positive pole of the welding arc. Root Opening  – A separation at the joint root between the work pieces. Root Crack  – A crack at the root of a weld. Self-Shielded Flux Cored Arc Welding (FCAW-S)  – A flux-cored arc welding process variation in which shielding gas is obtained exclusively from the flux within the electrode.

Shielded Metal Arc Welding (SMAW)  – A process that welds by heat from an electric arc, between a flux-covered metal electrode and the work. Shielding comes from the decomposition of the electrode covering. Page-A6.7 Shielding Gas – Protective gas used to prevent atmospheric contamination. Soldering  – A joining process using a filler metal with a liquidus less than 840 °F and below the solidus of the base metal. Solid State Welding  – A group of welding processes which produces coalescence at temperatures essentially below the melting point of the base materials being joined, without the addition of a brazing filler metal. Pressure may of may not be used. Solidus  – The highest temperature at which a metal or alloy is completely solid. Spatter – Metal particles expelled during welding that do not form a part of the weld. Spray Transfer  – In arc welding, a type of metal transfer in which molten filler metal is propelled axially across the arc in small droplets. Standard Temperature and Pressure (STP)  – An internationally accepted reference base where standard temperature is 0 °C (32 °f) and standard pressure is one atmosphere, or 14.6960 psia. Stick-Out – The length of unmelted electrode extending beyond the end of the contact tube in continuous welding processes. Straight Polarity  – Direct current arc welding where the work is the positive pole. Stress Relief Heat Treatment  – Uniform heating of a welded component to a temperature sufficient to relieve a major portion of the residual stresses. Stress Relief Cracking  – Cracking in the weld metal or heat affected zone during post-weld heat treatment or high temperature service. Stringer Bead  – A weld bead made without transverse movement of the welding arc. Submerged Arc Welding – A process that welds with the heat produced by an electric arc between a bare metal electrode and the work. A blanket of granular fusible flux shields the arc. Substrate – Any material upon which a thermal-spray deposit is applied. Synergistic – An action where the total effect of two active components in a mixture is greater than the sum of their individual effects. Tack Weld  – A weld made to hold parts of a weldment in proper alignment until the final welds are made. Tenacious  – Cohesive, tough. Tensile Strength – The maximum stress a material subjected to a stretching load can withstand without tearing. Thermal Conductivity – The quantity of heat passing through a material. Thermal Spraying  – A group of processes in which finely divided metallic or non-metallic materials are deposited in a molten or semimolten condition to form a coating. Thermal Stresses  – Stresses in metal resulting from non-uniform temperature distributions. Thermionic  – The emission of electrons as a result of heat. Throat  – In welding, the area between the arms of a resistance welder. In a press, the distance from the slide centerline to the frame, of a gap-frame press. TIG Welding  – See Gas Tungsten Arc Welding (GTAW). Torch Standoff Distance – The dimension from the outer face of the torch nozzle to the work piece. Transferred Arc – In plasma arc welding, a plasma arc established between the electrode and the work-piece. Underbead Crack – A crack in the heat-affected zone generally not extending to the surface of the base metal. Undercut – A groove melted into the base plate adjacent to the weld toe or weld root and left unfilled by weld metal.