Electrodes

15

Shielded-metal Electrodes

IEW TERMS

coated electrodesdrag techniquefast-fill electrodefast-follow electrodefast-freeze electrodefill-freeze electrodeiron powder electrodelow-hydrogen electrode

When you have finished this chapter, youshould be able to:

• describe the types of arc weldingelectrodes

• name the different types of coated elec-trodes and tell for what type of workthey are used

• tell how electrodes are classified

As with filler rods, there are many differ-ent types of electrodes on the market. Thereare even more types of electrodes, however,because an electrode must conduct current aswell as melt into the weld. For this reason, anelectrode needs more properties than does asimple filler rod.

There are three types of arc welding elec-trodes: filler metal in the form of a wire or rod,either bare or covered; bare filler metal; andmetal with a thick covering for the purpose ofstabilizing the arc and improving the fillermetal.

As a rule, bare metal electrodes produce apoor weld. The ductility is low, as is resistanceto stress. This occurs because of oxidation andbecause certain elements of the electrodemetal vaporize during welding. This chapterwill discuss primarily those coated mild steeland low alloy electrodes used with shieldedarc welding. Shielded electrodes make upabout 80% of those used by the industry.

Covered electrodes shield both the arcand the weld metal from the atmosphere. The

272 Welding Technology

crater depth, the penetration of the arc and thespeed of welding are all influenced by thematerial used to cover the electrode. Heat pen-etration, in turn, affects such things asannealing and recrystallization. The electrodecovering will also slow down the cooling rateof the molten metal and influence the shape ofthe weld.

Some electrodes contain alloys such asmolybdenum or vanadium to improve theweld's physical properties or to replace ele-ments lost during heating.

In the earlier chapter on basic arc weld-ing, practice welds were generally made withthe same electrode. This all-purpose electrodewas chosen to provide common practiceexperiences.

There are many ways to change a welder'sresults. Earlier, different currents and polari-ties were discussed, to show how they affectedthe weld joint. Also arc length, electrodediameter, and welding positions were dis-cussed. All these factors are very important forgood welding and for correcting any mistakesmade while welding. They might be calledvariables, because they can be changed.

An important variable is the electrodeitself. Because different electrode types (notdiameters) have different qualities, a weldercan choose an electrode to produce differentresults.

ELECTRODE COATINGS

Electrodes with a flux around the wire arecalled coated electrodes. The coating may beapplied by spraying, painting, or dipping influx. Oxides and nitrites that would normallyreduce the weld strength are partly excludedby a short arc, but the flux added to the rodfurther protects the metal with a gaseousshield. Manufacturers develop their own spe-cial electrode coating.

Each type of electrode is manufactureddifferently because of the difference in thecoating materials. A coating may represent aslittle as 1% of the electrode's weight. The coat-ing may be applied by dipping the wire into aquick-drying liquid flux. This type is medium,or semi-coated.

Heavily coated electrodes are made by atype of extrusion where the coating is forcedonto the wire as it passes through a press.Another method is by dipping the wire into aliquid flux several times, with a drying timebetween each dipping.

A solution of sodium silicate, gums, lac-quers, and various glues are the most commonmaterials used for binding the flux to the wire.

The coating on the electrodes is eithermade of cellulose or mineral. The flux on someelectrodes contains a mixture of both types.

Cellulose coatings usually burn away toform a gas in the arc. These coatings are beingreplaced by coatings made from sodium sili-cate or titanium dioxide that do not burn awayso quickly.

Mineral coatings, on the other hand, aremade of silicates and metallic oxides. Rodscovered with mineral coatings produce a greatdeal of slag over the weld area, protecting itfrom the harmful effects of the atmosphere.

• High cellulose content. Electrodes have rapidburn-off and deep penetration with this flux.Welds can be made in all positions, but they areusually used for vertical-down pipe welding andstructural work. Usually, rods with this type offlux are used with DC reverse polarity.• Titania content. Flux containing titaniamakes welding easier. The molten metal is sup-ported by a thick, heavy slag, making the elec-trode suitable for vertical and horizontal filletwelds. Titanium dioxide is fast becoming themost important substance for mineral-coatedelectrodes. These are used on AC or DC machineswith either polarity.• Titania and basic compounds. Flux contain-ing titania and added basic compounds (ferro-manganese, sodium silicates, feldspar) have amore fluid slag that produces a smooth arc withmedium penetration, suitable for all-positionwelding. They can be used on AC or DCmachines with either polarity.• Manganese, iron, and silicates. This flux con-sists of oxides or carbonates of manganese, iron,and silicates, making slag removal easy. Elec-trodes containing this flux are used in the flatposition, usually with DC reverse polarity.• Iron oxide content. Iron oxide flux gives lowpenetration resulting in lower tensile strength.However, the welds are smooth in appearance.• Calcium carbonate fluxes. This is a low-mois-ture flux made of calcium carbonate with fluorideas limestone and fluospar. These are low-hydro-gen electrodes, popular when welding high-car-

Shielded-Metal Electrodes 273

bon or high-sulfur steels. Calcium carbonatefluxes must be kept dry. When iron powder isadded, higher heats are possible with smallerelectrode cores.

The main stabilizers in these coatings arecalcium carbonate, feldspar, and titaniumdioxide. To control porosity, a deoxidizer offerro-manganese is added. Molybdenum orother alloys may also be added to the coatings.

CLASSIFYING ELECTRODES

Electrodes used in the United States andCanada are approved by the American Weld-ing Society and assigned a letter, such as thosein Table 15-A, and a number. The electrode

Table 15-A. Electrode Classifications.

Prefix Letters

The following prefix letters are used to indicate either a product form or atype of operation, or both:E—Indicates an arc welding electrode, which carries the arc welding current.R—Indicates a welding rod which is heated by other means than by carrying

the arc welding current.ER—indicates a filler metal which may be used either as an arc welding

electrode or as a welding rod.EC—Indicates a composite electrode.EW—Indicates a (nonconsumable) tungsten electrode.B—Indicates a brazing filler metal.RB—Indicates a filler metal which may be used as a welding rod or as brazing

filler metal, or both.RG—Indicates a welding rod to be used in oxyfuel gas welding.F—Indicates a flux for use in submerged arc welding.

number on the box means that the electrodeshave met the standards set up by the AWS.

In these classifications, the prefix E is fol-lowed by a number series which indicatesstrength level, position capability, and type ofcovering and welding current.

The letter E designates "electrode." Thefirst two digits, 60 for example, indicate theminimum tensile strength of the depositedmetal in thousands of pounds per square inch.The third digit indicates the position in whichthe electrode can make satisfactory welds.Thus, the "1," as in E 6010, means that theelectrode is satisfactory for use in all positions(flat, vertical, overhead, and horizontal). The"2," as in E 6020, indicates that the electrode issuitable for depositing satisfactory welds in

the flat position and for making horizontalfillet welds. The last digit indicates the currentand type of covering on the electrode. SeeTable 15-B.

When comparing electrodes, keep in mindthat the wire in all of the above electrodes isthe same, including the wire in the E 6015 andE 6016 electrodes. It is the flux that causes thedifferent handling and deposited weld metalqualities. It should also be noted that the abil-ity to stretch goes down as the tensile strengthgoes up. Therefore, a welder should not expectan E 80XX or E 90XX electrode to have theability to stretch of an E 60XX electrode. (TheX's represent all possible varieties in thosecategories.)

CHOOSING AN ELECTRODE

Electrodes are usually chosen on the basisof job requirement. A welder must look the jobover carefully to figure out just what the elec-trode must be able to do.

Within the selected group, an electrodeshould be chosen that has the physical proper-ties and operating characteristics that the jobneeds. Special characteristics of other elec-trodes in different groups should be checkedto be sure that all possible choices have beenconsidered. If more than one electrodeappears suited for the job, they all should betried. One electrode may prove to be better forthat particular work.

Basically, an electrode should be chosenby considering these factors:

properties of the base metalposition of the jointtype of jointamount of welding requiredtightness of the joint's fit-uptype of current available

Mild Steel Electrodes

Electrodes behave differently in use. Fast-fill electrodes deposit metal rapidly. Theytend to be heavily coated, produce smoothbeads, and leave a thick slag that peels offeasily.

274 Welding Technology

Table 15-B. Requirements for Common Electrodes.

AWS Classification Type ol CoveringCapable ol Producing Satisfactory

Welds In Positions Shown Type of Current

E60 Series-Minimum Tensile Strength of Deposited Metal In As-Welded Condition60 000 psl (or Higher-see Table 4, AS.1)

E6010E6011E6012E6013E6020

E6027

High cellulose sodiumHigh cellulose potassiumHigh titania sodiumHigh titania potassiumHigh iron oxide

Iron powder, iron oxide

F, V, OH. HF, V, OH. HF, V. OH, HF, V, OH. HH-Fillets.F

H-Fillets,F

dc, reverse polarityac or dc, reverse polarityac oac oac oac oac oac o

dc. straight polaritydc. either polaritydc, straight polaritydc, either polaritydc, straight polaritydc, either polarity

E70 Series-Minimum Tensile Strength of Deposited Metal In As-Welded Condition70 000 psl (or Higher-see TAble 4, AS.1)

E7014E7015E7016E7018E7024E7028

Iron powder, titaniaLow hydrogen sodiumLow hydrogen potassiumIron powder, low hydrogenIron powder, titaniaIron powder, low hydrogen

F, V. OH. HF, V, OH, HF. V. OH, HF, V, OH, HH-Fillets, FH-Fillets. F

ac or dc. either polaritydc, reverse polarityac or dc, reverse polarityac or dc, reverse polarityac or dc, either polarityac or dc, reverse polarity

Fast-freeze electrodes deposit metal thatsolidifies (freezes) rapidly. This is importantwhere there is a chance of slag or weld metalspilling out of the joint, as in overhead or verti-cal positions.

Electrodes which combine the character-istics of both fast-freeze and fast-fill are calledfill-freeze or fast-follow electrodes. There isconsiderable difference among these types.Some are mostly fast-fill, others are mostlyfast-freeze.

Low-hydrogen electrodes are those withcoatings containing practically no hydrogen.They produce welds that resist cracks underthe bead and are exceptionally ductile. Theysimplify procedures on hard-to-weld andhigh-tensile alloy steels by reducing thepreheat needed. Also, porosity is eliminatedwhen welding steels with a high sulfur con-tent. A low-hydrogen electrode will also helpeliminate hot shortness in steels containingphosphorus.

The iron in iron powder electrodes is con-verted to steel in the intense arc heat. Whenthere is a large amount of iron powder thewelding speed increases, the arc is more sta-ble, spatter is reduced, and slag is easier toremove.

Most electrodes fall into more than one ofthe above categories. For instance, an elec-

trode with high iron powder content is alsoprobably fast-fill. The designations aregeneral.

£ 6010 and E 6011 (Fast-freeze)

Joints requiring deep penetration, such assquare edge butt joints, are welded in the flatposition with the larger sizes'of these fast-freeze electrodes. They are used for galvanizedsteel because the forceful arc bites through thegalvanizing and the light slag reduces bub-bling while helping prevent porosity. E6010electrodes have a high cellulose content in thecoating, which produces large volumes of car-bon dioxide and water vapor. This protectsthe deposited metal from the atmosphere eventhough the slag deposit is very low. In mostcases, the slag can be removed easily with awire brush. Since the slag deposit is low, theweld cools quickly, making the electrode easyto use in vertical and overhead positions.

Sheet metal edge and butt welds on 10- to18-gauge steel are welded with these elec-trodes while using straight polarity. This pro-duces a fine "spray" arc with little penetrationand excellent fill ability. They deposit a smallbead on 10- to 18-gauge sheet steel with highspeeds and few skips. This rod can also be

Shielded-Metal Electrodes

sed on straight polarity for light sheet metalhile using very low heat.

Since the quality of the deposited metal is)od, the electrode is used for structural steel'ection and pipe welding. General-purpose'elding is usually done with these electrodes,specially when most of the work is out ofosition, dirty, or greasy. Deep penetrationroduces the best possible results under thesedverse conditions, with the added benefit ofnly light slag.

Since this rod is listed as E 6010, it shouldlave 60,000 psi [4216 kg/cm2] tensile strength,iowever, the deposited weld metal, unlessitress-relieved or annealed, will probablylave a higher tensile strength. It may be from55,000 to 75,000 psi [4568 to 5270 kg/cm2], or2ven higher if the weld was cooled quickly.

The elongation will probably be 22% to28% in two inches. If stress-relieved, the ten-sile strength will be 60,000 to 72,000 psi [4216to 5059 kg/cm2], and the elongation will beabout 29% to 37% in two inches.

In the flat position, a close arc withenough travel speed to stay ahead of the mol-ten pool is required. In Fig. 15-1, the welder is

ELECTRODEANGLE

15°

DISTANCE FROM ROD TO WORK]MUST BE NO MORE THAN

ROD DIAMETER

15-1. The practice set-up for the E6010 electrode.

set up to practice a flat weld with an E 6010electrode. Note the electrode position andsafety equipment.

The vertical position gives better penetra-tion with a vertical-up weld, Fig. 15-2. Verti-cal-down, however, allows faster welding. For

90° ELECTRODEANGLE

15-2. Practicing vertical-up welding with the E6010electrode.

ROD INCLINATION SIMILARFLAT POSITION WELDING

15-3. Practicing overhead welding with the E6010electrode.

ROD POSITIONAPPROX. 90°

15-4. Practicing horizontal welding with the E6010electrode.

276 Welding Technology

that reason, pipeline welders often use the ver-tical-down method.

Practicing overhead and horizontal buttwelds with the E 6010 electrode is shown inFigs. 15-3 and 15-4. These welds can best bemade with stringer beads.

E 6011 electrodes are made to be usedwith an AC or DC welding machine. They pro-duce results equal to the E 6010 rod, whichcannot be used with an AC machine. TheE 6011 rod can usually be used on any workwhere an E 6010 rod is specified. The amper-age setting on a DC machine should be 10%less than that of an AC machine.

E 6012, E 6013, E 6014, and E 7014 (Fill-freeze)

The E 6012 electrode can be used in allpositions. It is a reliable general-purpose andproduction electrode with a forceful arc andshould be used with straight polarity DC,although it also operates well on AC. Iron con-tent provides very good deposit rates. Excel-lent for low-current jobs, it resists sticking andproduces a smooth and steady arc. The low-current E 6012 gives minimum spatter andallows easy slag removal.

Although this electrode does not have thestretching qualities of an E 6010, it has a veryuseful place in welding because its heavy slagcovers the weld, protecting it from the atmos-phere. If the E 6012 is properly applied, slagremoval is easy, leaving the weld metal brightand clean. Penetration is somewhat lowerthan the E 6010, but the burn-off is faster. Thismakes it economical for production work.

Although the E 6012 is an easy electrodeto handle, slag can be trapped in the weld,preventing root penetration, if the welder isn'tcareful. On large weldments and in coldweather, the first and second beads may crackif they are not preheated. The E 6012 is usedextensively for building up mild steel shafts,sheet metal, fabricating structural steel, andgeneral welding.

Although the composition of the core wireis the same as the E 6010, the as-welded resultsare different. As welded, the tensile strength isabout 70,000 to 82,000 psi [4919 to 5762/kg/cm2]. Elongation in 2" [50.8 mm] is about 18%

to 23%. After stress-relieving the weld, theapproximate results would be: tensilestrength, 65,000 to 80,000 psi [4568 to 5622 kg/cm2]; elongation in 2", 24% to 27%.

When practicing with either the E 6012 or

15-5. Using the E6012 electrodeto practice forehand arc weldingin the flat position.

Shielded-Metal Electrodes 277

E 6013, forehand welded stringer beads shouldbe used for the first pass, although on jointswith poor fit-up, a slight weave is preferred.Either stringer or weave beads can then beused for succeeding passes with a %" [3.2 mm]or shorter arc. As usual, tip the holder in thedirection of travel and move as fast as possiblewhile keeping a desired bead size, Fig. 15-5.Use currents in the middle to high range.

The E 6013 electrode is very popularbecause of its flexibility in operation. It pro-vides excellent AC operation and is softer andsteadier with less sticking than the E 6012electrodes; however, it is somewhat slower. Itis widely used on sheet metal when appear-ance and ease of operation are more importantthan speed. It is also used for general-purposewelding with smaller, limited-input, lowopen-circuit voltage welders. Spatter loss islow, and the beads are bright, smooth, and flat,with easily removed slag, Fig. 15-6.

E 6014 and E 7014 electrodes contain ironpowder, providing the best fast-fill ability ofall the electrodes in this group. Many welderslike these electrodes, and their main use is onproduction welding of irregular-shaped partswhere some vertical-down welding must bedone. The E 6014 is actually a slightly changedE 6012 and E 6013 electrode, but it has betterphysical properties with lower spatter loss.Also, the E 6014 will stand more heat and has abetter rate of deposition.

Joints with poor fit-up can be welded withthe E 6014 and E 7014 when fast-fill electrodes(which would normally be used with good fit-up) may burn or spill through. These elec-trodes are often used in general-purpose weld-ing, particularly when only one or twoelectrodes will be used for all welding jobs.High-speed lap and fillet welds on 10- to 20-gauge metals are done with these electrodes.On those jobs, fast-follow ability becomesimportant.

The E 7014 electrode may be used on ACor either polarity DC with high currents andspeeds. On thin materials, DC straight polarityis preferred, especially for fillet or lap welds. Ahigher inclination angle can be used on filletwelds to help prevent the problem of doublebeading (a thick, partially unfused bead).

The E 7014 can be used with normal arc

WELDBEAD

15-6. A Tjoint fillet weld made with an E6013 electrodehas smooth, flat beads, and easily removed slag.

techniques, or it can be used with the dragtechnique shown in Fig. 15-7. With the dragtechnique, the electrode is held at more of anangle and pulled along inside the groove. Thiselectrode has very easy slag removal with verylow spatter loss. It is used for many out-of-position welding jobs, especially verticaldown.

E6015 and E6016 (Low-hydrogen)

The E 6015 should be used on direct cur-rent, reverse polarity. It is very similar to theE 6016. The E 6016, however, can also be usedwith DC straight polarity or AC.

The E6015 and E6016 electrodes werefirst developed for welding steels that crackedin the bead area when welded with ordinaryelectrodes. Steels that were then classified ashard-to-weld contained small percentages ofchromium, nickel, molybdenum and otheralloying elements that produce medium andhigh-carbon steels. It was found that hydrogenwas responsible for the bead cracking in thesewelds. Therefore, the flux on the E 6015 andE 6016 electrodes consists of materials thatproduce practically no hydrogen whenburned.

With E 6015 and E 6016, high heats can beused with little or no undercutting and little

278 Welding Technology

45° ELECTRODE INCLINATION INCREASEDFROM REGULAR FLAT WELD TECHNIQUE

15-7. The drag technique using anE7014 electrode.

spatter loss. Both preheating and postheatingare recommended when materials likely tocrack are being welded. Although these elec-trodes are all-position types, it is recom-mended that electrodes over %2" [4.0 mm] indiameter not be used for vertical and overheadwelding.

E 6018, E 7018, E 7016, E 6028, and E 7028(Low-hydrogen)

The E 6018, like the other low-hydrogenelectrodes, depends on the flux for its capacityto weld hard-to-weld materials. The E 6018 isused with either direct current, reverse polar-ity or alternating current. Penetration is shal-low, even when using a short arc with littlespatter loss.

E 7018 and E 6018 electrodes are similar toE 7016 and E 6016 electrodes and are for out-of-position (other than flat) work. Iron powderin the coating gives high deposit rates, consid-ering that the welding is being done out ofposition. The E 7028 and E 6028 electrodeshave a high iron powder content that isresponsible for the deposit rates and welderpopularity of fast-fill electrodes. Yet theseelectrodes retain the quality of low hydrogendeposits. The slag cleans easily, and they areused mainly on flat and horizontal welds.

These rods may be used with alternating

current or reverse polarity direct current.They should usually be welded using the max-imum amperage that the job will permit,within the recommended range. Because theyare low hydrogen, they should be welded witha short arc to keep atmospheric gases out ofthe molten metal.

In practicing with these electrodes, dragthe electrode lightly or hold a shorter arc, notover %" [3.2 mm]. A long arc should not beused at any time, since these electrodes rely onmolten slag for shielding. Stringer beads orsmall weave passes are better than wideweave passes.

When these electrodes are used in the ver-tical position, they should be welded verticalup with %" or %2" [3.2 mm or 4.0 mm] diameterelectrodes and a triangular weave. A shelf ofweld metal is built and, with a weave tech-nique, layer upon layer of metal is depositedas the weld progresses up the joint.

In overhead practice %" or %2" [3.2 or4.0 mm] diameter electrodes should be usedwith a slight circular motion in the crater. Ashort arc is maintained. Motions should beslow and deliberate. The electrode is pointeddirectly into the joint and the holder tiltedslightly forward in the direction of travel.Practice moving fast enough to avoid spillingthe weld metal, although the slag will spill tosome extent. Use welding currents in the

Shielded-Metal Electrodes 279

15-8. An old refrigerator converted todry storage for welding rods.

lower portion of the recommended range.Low-hydrogen electrodes must be kept

dry. They should either be used as soon asthey are taken from freshly-opened contain-ers, or they should be stored in a warm, dryplace. Otherwise, they will pick up moisturefrom the air and lose some of their low-hydro-gen properties. An old upright refrigeratorwith a small heat lamp inside will serve thepurpose, Fig. 15-8.

Electrode manufacturers and weldingengineers recommend the use of an electrodestabilizing oven if X-ray quality welds withconsistent physical properties are desired,Fig. 15-9.

15-9.Air)

An electrode stabilizing oven. (Canadian Liquid

E 6020 (Low-hydrogen)

This rod should be used only in horizon-tal welding positions. Due to its extremelygood finish and ease of handling, it is oftenused for fillet welding. The penetration isexcellent, so the fit-up must be good for bestresults. Due to the excellent quality of theweld metal, it is highly recommended for workon vessels which will later be X-rayed. Largerrods can be used due to the high heat input,making flat welding faster and more economi-cal. The weld qualities with this electrode areexcellent, with little spatter loss.

E 6024, E 6027, and E 7024 (Iron powder)

The E 6024 is either the E 6012 or E 6013with iron powder added. It is a fast-fill elec-trode that works equally well on reverse orstraight polarity direct current or on alternat-ing current. It has been found that the E 6024,when used on mild steel for horizontal filletsand flat welds, gives a good convex beadappearance. Penetration is shallow and slagremoval is easy.

The E 6027 (the E 6020 with iron powder)operates well on alternating current or eitherpolarity direct current for flat fillet welding.Either straight polarity direct current or alter-

280 Welding Technology

nating current is more satisfactory when weld-ing in the horizontal position.

The E 6027, E 6024, and E 7024 electrodeswill all deposit metal rapidly. Their fast-fillmight be considered the opposite of fast-freezeand is the most outstanding characteristic ofthis group of electrodes. E 6024 and E 7024, theheavily coated, iron powder electrodes, havehigh deposit rates, produce exceptionallysmooth beads, and have a thick, dense slagthat tends to peel off the weld. Operating qual-ities are the biggest difference between thetwo electrodes.

Small sizes (Ys" to 3/16" [3.2 to 4.8 mm]) of

E6024 and large sizes (7/32" to 5/)6" [5.6 to7.9 mm]) of E 7024 have faster speeds, higherdeposit rates, and smoother arc action thantheir counterparts. By contrast, small sizes ofE 7024 and large sizes of E 6024 offer greaterarc force, better control of the molten poolduring arc blow or when the work is in thevertical position, and a flatter bead shape.

The E 6027 also has a heavy iron powdercoating and high deposit rates. Although theE 6027 has an excellent bead appearance, thebead is not quite as smooth. Its slag is crumblyand easily removed from any joint. The E 6024electrodes penetrate lightly, so there is littlepickup of alloy from the base metal. Theyleave high-strength deposits which are almostas crack resistant as those of low-hydrogenelectrodes.

With these rods, AC current produces thebest speeds and operating characteristics.Reverse polarity DC may also be used,although it may cause arc blow and compli-cate control of the molten puddle.

When welding in the flat position withthese electrodes, use the drag technique anddeposit stringer beads. The electrode shouldbe held perpendicular to the work with the

holder tipped forward about 30° in the direc-tion of travel.

£ 6030 (Iron powder)

This electrode is recommended for heavyflat welding only. The E 6030 is being replaced,to a large extent, by the E 6027 because thespeed of the E 6027 is faster. The E 6030 willwork on either AC or DC and provides excel-lent results when welding under X-ray condi-tions. The slag comes off easily, and the finishis smooth, clean, and bright.

70XX, 80XX, 90XX, 100XX

Rods with 7010 and 70XX ratings are usu-ally alloyed. The alloys are often in the fluxcoating where they will mix with the moltenmetal in the weld puddle. For this reason, awelder must maintain puddle control on out-of-position welds for good results. It shouldalso be noted that, even with the increasedtensile strength, the ductility as welded isapproximately the same as the E 6012 elec-trode. The tensile strength range for the 7010 is77,000 to 82,000 psi [5411 to 5762 kg/cm2],while the E 6012 is from 71,000 to 82,000 psi[4989 to 5762 kg/cm2].

80XX, 90XX, and 100XX electrodes arealloyed for special purposes. It is always safeto use the current and positions as recom-mended by the manufacturer.

Discussion Questions

1. Name as many electrode coatings as you can.2. Tell what the numbers in E 6020 represent.3. What factors must be considered when

choosing an electrode?4. What are the differences between fast-fill,

fast-freeze, and fill-freeze electrodes?