ARC WELDING TECHNOLOGY - SharpSchoolwbsdeast.sharpschool.net/UserFiles/Servers/Server_2992254/File/Departments/Tech Ed...moisture testing chosen by ESAB is that described in Section

ARC WELDING TECHNOLOGYA Correspondence Course

LESSON IVCOVERED ELECTRODES FOR

WELDING LOW ALLOY STEELS

AN INTRODUCTION TO LOWALLOY COVERED ELECTRODES

ESAB ESAB Welding &Cutting Products

©COPYRIGHT 2000 THE ESAB GROUP, INC.

- i - © COPYRIGHT 1998 THE ESAB GROUP, INC.

Section Nr. Section Title Page

TABLE OF CONTENTSLESSON IV

COVERED ELECTRODES FOR WELDINGLOW ALLOY STEELS

4.1 LOW ALLOY STEELS ...................................................................... 1

4.2 Consequence of Hydrogen in Low Alloy Steel .................................. 14.2.1 Preheat ............................................................................................. 3

4.3 MANUFACTURING LOW HYDROGEN ELECTRODES .................. 34.3.1 Storage and Reconditioning .............................................................. 44.3.2 Moisture Resistant Coating ............................................................... 4

4.4 AWS SPECIFICATION FOR LOW ALLOY ELECTRODES.............. 54.4.1 Effect of Alloying Elements ............................................................... 64.4.2 Mechanical Properties (AWS A5.5-96) ............................................. 74.4.3 Impact Properties.............................................................................. 8

4.5 SELECTING THE PROPER LOW ALLOY ELECTRODE ................ 84.5.1 Service Conditions ............................................................................ 84.5.2 Joint Design ...................................................................................... 94.5.3 Equipment......................................................................................... 10

4.6 LOW HYDROGEN IRON POWDER ELECTRODES ....................... 114.6.1 Atom Arc 7018 (AWS E7018) ........................................................... 114.6.2 Atom Arc 7018 Mo (AWS E7018-A1)................................................ 114.6.3 Atom Arc 8018N (AWS E8018-C2) ................................................... 124.6.4 Atom Arc 8018CM (AWS E8018-B2) ................................................ 134.6.5 Atom Arc 8018W (AWS E8018-G) .................................................... 134.6.6 Atom Arc 9018CM (AWS E9018-B3) ................................................ 144.6.7 Atom Arc 9018-B3L (AWS E9018-B3L) ............................................ 144.6.8 Atom Arc 10018 (AWS E10018-M) ................................................... 154.6.9 Atom Arc 10018MM (AWS E10018-D2) ........................................... 154.6.10 Atom Arc 12018 (AWS E12018-M).................................................... 16

- ii - © COPYRIGHT 2000 THE ESAB GROUP, INC.

Section Nr. Section Title Page

4.6.11 Atom Arc "T" (AWS E11018-M) ......................................................... 164.6.12 Atom Arc 9018HT (AWS E9018G) .................................................... 174.6.13 Atom Arc 4130 (No AWS Classification) ............................................ 174.6.14 Atom Arc 4130 LN (No AWS Classification) ...................................... 17

Appendix A Stick Electrode Data Charts - Atom Arc Electrodes .......................... 19

Appendix B Glossary of Terms ............................................................................. 20

TABLE OF CONTENTSLESSON IV- Con't

- 1 - © COPYRIGHT 2000 THE ESAB GROUP, INC.

LESSON IV

COVERED ELECTRODES FOR WELDINGLOW ALLOY STEELS

4.1 LOW ALLOY STEELS

Low alloy steels, as discussed in Lesson I, are those steels to that have small amounts ofalloying elements added for specific purposes; i.e., to increase strength, toughness, corrosionand rust resistance, or to alter the response to heat treatment. Nearly every steel manufacturermakes a family of low alloy steels that are usually sold under trade names such as Maynari R,Cor-ten, Man-ten, and many others. Many of the steels are designed to develop their specificproperties such as high strength or toughness in the hot rolled and controlled cooling condition,rather than by subsequent heat treatment. Other compositions of low alloy steels are designedto develop specific properties following heat treatments. Examples of these types are U.S.Steel T-1, Armco Steel SS-100, Great Lakes Steel NA XTRA 100, all of which are quenchedand tempered to reach high strength with good toughness. Covered low alloy welding elec-trodes are designed, in most cases, to match the properties of the low alloy steels rather thanto match the exact chemical composition of the steel. Exceptions to this are the chromiummolybdenum electrodes that need to contain about the same amounts of the alloy ingredientsas the steel in order to match the properties of the steel.

4.2 CONSEQUENCE OF HYDROGEN IN LOW ALLOY STEEL

One of the reasons that low alloy steels are becoming more popular is because of the exten-sive research that was conducted in the development of electrodes for welding them. Althoughspecial precautions and care are required in welding the low alloy steels, they can now bejoined with a high degree of reliability. But that was not always so. During World War II whenthere was a dramatic increase in the use of high strength low alloy steel, there was also acorresponding increase in weld defects. It was quickly realized that hardenable steels couldnot be welded in the same manner and with the same electrodes as were then commonly usedfor welding the lower strength mild steels. Through extensive research, it was found that en-trapped hydrogen was the culprit in causing weld defects, and the term "hydrogenembrittlement" became synonymous with red flags warning of impending disaster.

4.2.0.1 When hydrogen bearing compounds such as water, minerals, or chemicals arepresent in the electrode coating, as is common with mild steel electrodes, the chemicallycombined hydrogen is dissociated into atomic hydrogen by the heat of the welding arc. Themolten weld metal has the capacity to dissolve the atomic hydrogen. However, as soon as the


LESSON IV

weld metal solidifies, it loses the ability to hold the hydrogen in solution and the hydrogen iseither expelled into the atmosphere or moves throughout the weld zone. Steel and weld metalare not as solid as they appear to the naked eye, being filled with tiny submicroscopic pores.The hydrogen atoms are smaller than the crystalline structure of the steel or the weld metal,and the hydrogen can move about somewhat freely in the steel, just as air can move through afilter. The hydrogen atoms move out of the weld metal into the heat affected zone. The heataffected zone (HAZ) is an area of critical importance in welding, especially in welding highstrength steels.

4.2.0.2 The heat affected zone (See Figure 1) is that area of the weld joint that did notbecome molten in the welding process, but underwent a microstructure change as a result ofthe heat induced by the arc. Thiszone can become a weak link inthe normally very strong joint.First of all, the grain struc-ture of the HAZ is lessrefined and therefore,weaker than the sur-rounding unaffectedbase metal or the oncemolten weld metal.And secondly, if theHAZ is permitted to cooltoo rapidly in certain steels,a hard brittle crystalline struc-ture, known as Marsenite, is lockedin place. The relatively large pores ofthe heat affected zone are a natural collect-ing place for atomic hydrogen. When two hydrogen atoms meet, they immediately unite toform molecular hydrogen. The resulting molecules are larger than the crystalline structure ofthe metal and can no longer move about freely. As more and more hydrogen atoms come intothe pores, form molecules, and are trapped, tremendous pressure can develop. Mild steel andlower strength steels are sufficiently plastic to move a little with the hydrogen pressure and notcause the steel to crack. Steels that have high hardness and high strength do not have suffi-cient plasticity to move with the pressure, and if enough hydrogen is present, cracking of thesteel occurs.

HEAT AFFECTED ZONE

FIGURE 1

SOLIDIFIED WELD METAL

HEAT AFFECTED ZONE

UNAFFECTED BASE METAL


LESSON IV

4.2.0.3 This hydrogen caused defect, known as underbead cracking (See Figure 2), beginsin the HAZ making it particularly sinister since the crack is not immediately apparent to theeye. It occurs after the metal has cooled from about 400°F to room temperature, and it issometimes referred to as"cold cracking". The defectmay occur immediately aftercooling, or it may take hours,days, or even months beforeit happens.

4.2.1 Preheat - Steelsthat are highly hardenable bya rapid cooling in the heataffected zone require pre-heat and interpass temperature control.As preheat is applied to the steel, thecooling rate of the steel from higher temperatures is slowed. Maintaining a constant tempera-ture between each welding pass also helps to control this cooling. Slower cooling rates pre-vent the steel from being excessively hardened and thus, minimizes the chance of underbeadcracking. When this technique is combined with the use of low hydrogen electrodes, a highdegree of reliability can be expected from the welds.

4.3 MANUFACTURING LOW HYDROGEN ELECTRODES

The discovery of hydrogen related weld defects initiated the development of low hydrogenelectrodes. The functions of the coating with low hydrogen electrodes (i.e., shielding, arcstabilizers, alloy additions, etc.) are much the same as those listed in Lesson III for Mild SteelCovered Electrodes, but the coating is formulated with ingredients that lack hydrogen in theirchemical composition. This is primarily accomplished by eliminating organic and chemicalcompounds high in moisture content. In fact, control of the moisture levels in the coating iscritical in the manufacture and use of low hydrogen electrodes.

4.3.0.1 In addition to eliminating hydrogen in the coating formula, the manufacturing processentails a high temperature bake cycle. After the coating is extruded onto the core in the samemanner as a mild steel coated electrode, the low hydrogen electrodes are given an initial lowtemperature bake (300-400°F), and then rebaked in a separate high temperature oven (800-900°F) for a specified period of time. This procedure practically eliminates all moisture, andto guard against the reabsorbing of moisture that is naturally present in the atmosphere, the

BASE METAL

WELD METAL

HEAT AFFECTED ZONE

HYDROGEN INDUCED CRACKS

UNDERBEAD CRACKINGFIGURE 2

➤

➤

➤

➤


LESSON IV

electrodes are immediately packaged in hermetically sealed metal containers following thehigh temperature bake.

4.3.1 Storage and Reconditioning - All low hydrogen electrodes will absorb somemoisture from the air after the electrode container is opened. Therefore, those electrodes thatare not intended for use within a given period of time must be stored in a vented oven andmaintained at a constant temperature.

4.3.1.1 Various structural and military codes allow only specified times of exposure. Thesemay be anywhere from 30 minutes to 8 hours depending on the electrode alloy, the relativehumidity in the work area, and the critical nature of the application. If the low hydrogen elec-trodes are exposed to the atmosphere beyond these time limits, they must be scrapped orreconditioned by rebaking in a vented oven for a specified time at a specific temperature.

4.3.1.2 The recommended storage and rebake temperatures for Atom Arc low hydrogenelectrodes are follows:

STORAGE RECONDITIONED225-300°F 1 hr. @700°F

4.3.2 Moisture Resistant Coating - Moisture absorption is of special concern to end-users such as shipbuilders and oil rig fabricators who are situated in areas of the world thathave a high level of relative humidity. As the temperature and relative humidity increase, thechance of absorbing moisture in the low hydrogen coating is greatly increased. To combat thispossibility, major electrode manufacturers have in recent years developed low hydrogenelectrodes with moisture resistant coatings. These coatings low the rate of moisture absorp-tion in electrodes that have been exposed to the air for extended periods, thus adding an extradegree of reliability to low hydrogen electrodes.

4.3.2.1 The following graphs (figure 3) give an idea of the effectiveness of a moistureresistant coating. The tests were conducted on Atom Arc 7018 electrodes. The method ofmoisture testing chosen by ESAB is that described in Section 25 of the AWS A5.5-96 Specifi-cation. This method was chosen because it satisfies the AWS specifications and is sensitiveonly to water, making it one of the most accurate and reliable methods of moisture determina-tion currently in use.

4.3.2.2 The AWS structural code and military specifications allow a maximum of 0.40% and0.20% moisture content, respectively, for E70XX low hydrogen electrodes. As shown on thepreceding graphs, the Atom Arc 7018 electrode satisfied this low moisture requirement forexposure times beyond those normally allowed in field use.


LESSON IV

4.4 AWS SPECIFICATION FOR LOW ALLOY

ELECTRODES A5.5-96

With very few exceptions, low alloy electrodes are made by adding the appropriate alloyingelements to the electrode coating rather than having a core wire that matches the low alloysteel. Low alloy covered electrodes are classified according to the American Welding Societyfiller metal specification A5.5-96. This specification contains the mechanical property require-

EFFECTIVENESS OF MOISTURE RESISTANT COATING - ATOM ARC 7018 ELECTRODES

FIGURE 3

.40

.30

.20

.10

01 2 4 8 12 24 36 48 96

% M

oist

ure

Exposure Time (hours)

1 2 4 8 12 24 36 48 96

% M

oist

ure


.40

.30

.20

.10

0

1 2 4 8 12 24

% M

oist

ure


.40

.30

.20

.10

0

Moisture atZero Hours .09



70°F - 70% Relative Humidity



➤

➤

➤


LESSON IV

ments and stress relieved condition, the chemical requirements, and the weld metal sound-ness requirements. Electrodes are classified under this specification according to the me-chanical properties and chemical composition of the weld metal, the type of covering, and thewelding position of the electrode. The classification of the electrode is designated by themanufacturer according to the results of his own tests. The manufacturer, thereby, guaranteeshis electrode to meet the requirements of the AWS specification.

4.4.0.1 The letter-number designations for low alloy electrode classifications mean muchthe same as with mild steel electrodes, except that the major alloy composition is indicated bya letter-number suffix. For example, E7018-A1 indicates an electrode (letter E); with a mini-mum of 70,000 psi tensile strength (70); is weldable in all positions (1); is iron powder lowhydrogen (8); and contains nominally 1/2% molybdenum (A1). The full list of nominal alloycompositions for this specification is contained in Table 1.

4.4.1 Effect of Alloying Elements

4.4.1.1 Molybdenum - When mild steel weld metal is stress relieved, the yield point islowered 3,000 psi or more and the tensile strength is also lowered 3,000 psi or more. When1/2% of molybdenum is added to the weld, both the yield point and the tensile strength remainconstant from the as-welded to the stress relieved condition. The presence of molybdenumalso increases the tensile strength of the weld metal.

TABLE 1. Nominal Alloy Designations for AWS A5.5 Specification

A1 1/2% MolybdenumB1 1/2% Chromium, 1/2% MolybdenumB2 1-1/4% Chromium, 1/2% MolybdenumB2L Low Carbon version of B2 type. Carbon content is 0.05% or lessB3 2-1/4% Chromium, 1% MolybdenumB3L Low Carbon version of B3 type. Carbon content is 0.05% or lessB4L 2% Chromium, 1/2% Molybdenum, low carbon (0.05% or less)B5 1/2% Chromium, 1.1% MolybdenumC3 1% NickelC1 2% NickelC2 3% NickelD1 1-1/2% Manganese, 1/3% MolybdenumD2 1-3/4% Manganese, 1/3% MolybdenumM Conforms to compositions covered by Military specifications.G Needs only a minimum of one of the elements listed in the AWS A5.5 Table

for Chemical Requirements.


LESSON IV

4.4.1.2 Chromium - When chromium is added to the weld metal, the corrosion and hightemperature scaling resistance are increased. The combination of chromium and molybde-num allows the weld metal to retain high strength levels at medium high temperatures.

4.4.1.3 Nickel - Mild steel weld metal usually becomes brittle at temperatures below -20°F.The addition of 1-3% nickel to the weld metal enables the weld metal to remain tough at con-siderably lower temperatures. The presence of the nickel also makes the weld metal moreresistant to cracking at room temperature.

4.4.1.4 Manganese - The presence of 1-1/2% to 2% manganese in weld metal increasesthe tensile strength and when 1/3% molybdenum is added in combination, the high strengthweld metal is crack resistant.

4.4.1.5 It should be noted that the A5.5-96 specification covers not only the low alloy lowhydrogen electrodes, but also low alloy versions of the cellulosic, titania, and iron oxide typeelectrodes. A full list of all the electrodes covered by this specification is presented in Table 2.

TABLE 2. Electrode Classifications of AWS A5.5 Specification

E7010-A1 E8018-B2 E9015-B3L E11018-M

E7011-A1 E8018-B2L E9016-B3 E12018-M

E7015-A1 E8015-B4L E9018-B3

E7016-A1 E8016-B5 E9018-B3L EXX10-G

E7018-A1 E8016-C1 E9015-D1 EXX11-G

E7020-A1 E8018-C1 E9018-D1 EXX13-G

E7027-A1 E8016-C2 E9018-M EXX15-G

E8018-C2 EXX16-G

E8016-B1 E8016-C3 E10015-D2 EXX18-G

E8018-B1 E8018-C3 E10016-D2 E7020-G

2D-81001EL2B-5108E

E8016-B2 E9015-B3 E10018-M

4.4.2 Mechanical Properties (AWS A5.5-96) - Since many low alloy steels requiresome post-weld heat treatment to relieve the internal stresses generated from the weldingprocess, physical testing on the weld metal of most low alloy electrodes is required to beperformed after the specimen has been stress-relieved. Only the E8016-C3, E8018-C3,E9018-M, E11018-M, and E12018-M types are permitted to be tested in the as-welded condi-tion for classification purposes.


LESSON IV

4.4.3 Impact Properties - Since many low alloy steels are developed for low tempera-tures service, impact properties of the weld metal designed to join these steels are very impor-tant. Except for those types already mentioned, all impact testing is performed on specimensafter they have been stress-relieved. Table 3 lists the minimum charpy v-notch impacts re-quired in the A5.5 specification.

TABLE 3. Impact Requirements for AWS A5.5 Specification

AS WELDED MINIMUM REQUIREMENT STRESS-RELIEVED

E8016-C3 )------- 20 ft.-lbs. @-40°F.

E8018-C3 )

1D-5109E()M-8109E

1D-8109E()M-81001E

E11018-M )------- 20 ft.-lbs. @-60°F. -------- ( E10015-D2

2D-61001E()M-81021E

( E10018-D2

( E8016-C1

20 ft.-lbs. @-75°F. -------- ( E8018-C1

( E8016-C2

20 ft.-lbs. @-100°F.------- ( E8018-C2

Impact values for all other classifications are not required.

4.5 SELECTING THE PROPER LOW ALLOY ELECTRODE

As stated earlier, low alloy electrodes are often selected to match the properties of the steel tobe welded rather than matching the exact chemical composition of the steel. These properties(i.e., strength, toughness, creep, and corrosion resistance) reflect the type of service for whichthe steel is intended. The letter-number suffix of the electrode classification gives an indicationof that service. Whenever possible, the electrode should be selected on the basis of theappropriate strength levels and the intended service of the weldment.

4.5.1 Service Conditions - The large family of "proprietary" steels that are sold in the asrolled, controlled, cooled condition have a 50,000 psi minimum yield point and 70,000 psiminimum tensile strength. Electrodes that deposit low hydrogen weld metal of those strengthlevels are used to weld them.


LESSON IV

4.5.1.1 Some of the low alloy high strength steels are intended for use at subzero tempera-tures. Nickel bearing low hydrogen electrodes (C1, C2, C3 types) are available for such lowtemperature applications.

4.5.1.2 Chromium molybdenum low alloy steels are used for moderately high temperatureservice. Piping, tubing, boilers, etc., that are used extensively in power generating plants, arefabricated from these steels. Chrome-moly low hydrogen electrodes (B1, B2, B3, etc.) areproduced to weld these steels.

4.5.1.3 Many bridges and outdoor structures are constructed from "weathering" gradesteels. These are low alloy steels that, on exposure to the atmosphere, develop a thin, tightlyadhering layer of rust that prevents further rusting and eliminates the need for painting. Lowalloy electrodes with additions of chromium and copper are available for welding these steels.

4.5.1.4 Quenched and tempered low alloy steels usually develop high strength with goodtoughness. These types are used where substantial savings in the weight of the structure isimportant. Quite often, but not exclusively, these steels are used by the military. One of themore exotic applications for quenched and tempered low alloy steels is in the fabrication of thepressure hulls for nuclear submarines. The "M" series of high tensile low hydrogen electrodesis intended to weld these steels.

4.5.1.5 High tensile line pipe for the transmission of oil and gas is being used with greaterfrequency today. Low alloy cellulosic electrodes of the 7010 and 8010 variety are used forfield welding.

4.5.2 Joint Design - In fillet welding of high strength quenched and tempered steels, toecracking alongside the welds (see Figure 4) is frequently a problem. The toe cracking iscaused by the high strength weld metal having a higher yield point and tensile strength than thesteel.

4.5.2.1 When the weld area shrinks oncooling from the welding temperature, somethingmust give, and because the yield and strengthlevels of the steel are lower than those of theweld metal, cracking occurs in the heat affectedzone of the steel. The solution to this problem isto use a lower strength weld metal and increasethe fillet size to meet the weld joint strength requirements.

HEAT AFFECTEDZONE

CRACK AT TOEOF WELD

WELD METAL

BASEMETAL

➤

➤

➤

➤

TOE CRACKING

FIGURE 4


LESSON IV

With a somewhat lower strength weld metal as the filler, the yield point of the weld metal isreached during the shrinkage on cooling. The weld metal stretches without overloading in theheat affected zone of the steel and there is no cracking.

4.5.3 Equipment - The electrode selected will operate only on the appropriate powersource. Table 4 lists the type of current for which each class of electrode is designed.

TABLE 4. Current Requirements for AWS Electrode Classes

Electrode Class CurrentEXX10-X* DCRP

ro CAX-11XXE DCEP CD ro CAX-31XXE either polarity

EXX15-X DCEP ro CAX-61XXE DCEP ro CAX-81XXE DCEP ro CAX-02XXE DCEN (horizontal fillet)

AC or DC either polarity (flat) ro CAX-72XXE DCEN (horizontal fillet)

AC or DC either polarity (flat)* "X" indicates a variable in the classification.


LESSON IV

4.6 ESAB ATOM ARC LOW HYDROGEN IRON POWDER

ELECTRODES - FEATURES AND DATA

4.6.1 Atom Arc 7018 (AWS E7018) - Although this electrodes is really of the mild steelcategory and classification, the mechanical properties of the weld metal are sufficient to meetthe similar properties of the 50,000 psi yield and 70,000 psi tensile strength steels. Usually,preheat and interpass temperature control of those steels is not necessary when welding withAtom Arc 7018, although heavier thicknesses of steel may require some preheat. Commonapplications include: welding carbon steels, high sulfur steels, enameling steels, and somelow alloy, high tensile steels.

Typical Mechanical Properties of Weld MetalAs Welded Stress-Relieved

000,26005,86isp ,tnioP dleiYTensile Strength, psi 75,000 72,000

2313)"2( noitagnolE %775.57noitcudeR %

Charpy V-Notch Impact @72°F. 125 ft.-lbs. 130 ft.-lbs.@-20°F. 70 ft.-lbs. 75 ft.-lbs.

Typical Chemical Composition of Weld MetalC Mn Silicon

0.06% 1.10% 0.50%

4.6.2 Atom Arc 7018 Mo (AWS E7018-A1) - This electrode, which deposits 1/2%molybdenum weld metal, is useful in welding power piping and pressure vessels ofmolybdenum bearing steels designed for use at elevated temperatures. Typical applicationsinclude: welding of low carbon and carbon-moly tubes and piping, forged alloy steel pipeflanges, fittings and valves for high temperature service, carbon-moly steel boiler andsuperheater tubes, manganese-moly and manganese-moly-nickel pressure vessel plates, highstrength structural steel and steel castings for highway service.


LESSON IV

Typical Mechanical Properties of Weld MetalAs Welded* Stress-Relieved*


0303)"2( noitagnolE %Charpy V-Notch Impact @72°F. 95 ft.-lbs. 95 ft.-lbs.

@-10°F. 85 ft.-lbs. 85 ft.-lbs.@-40°F. 70 ft.-lbs. 70 ft.-lbs.

Typical Chemical Composition of Weld MetalC Mn Ni

0.04% 1.06% 2.37%

4.6.3 Atom Arc 8018N (AWS E8018-C2) - 8018N electrodes with 3% nickel are usuallyused to weld 3% nickel steels for low temperature service. It has solved many weld crackingproblems by its weld crack resistance, as well as remaining tough at temperatures as low as -100°F. Typical applications include: welding of piping for low temperature service, carbon andlow alloy steel forgings and ferritic steel castings for high pressures at low temperatures, highstrength steel castings for structural purposes, carbon steel forgings for railroad use andconcrete reinforcement bars.

Typical Mechanical Properties of Weld MetalAs Welded Stress-Relieved


8252)"2( noitagnolE %4755aerA fo noitcudeR %

Charpy V-Notch Impacts @72°F. 110 ft.-lbs. 112 ft.-lbs.@0°F. 91 ft.-lbs. 93 ft.-lbs.@-40°F. 73 ft.-lbs. 63 ft.-lbs.@-100°F. 35 ft-lbs. 30 ft.-lbs.

Typical Chemical Composition of Weld MetalC Mn Si Ni

0.5% 0.84% 0.37% 3.30%


LESSON IV

4.6.4 Atom Arc 8018CM (AWS E8018-B2) - This 1-1/4% chrome, 1/2% moly electrodedeposits weld metal that retains high strength at temperatures up to 600°F. The 8018CMelectrodes are used to weld the 1/2% chrome-1/2% moly, 1% chrome-1/2% moly steels, aswell as the 1-1/4% chrome-1/2% moly power piping, boiler tubing, plates and castings. Manyof the fossil fired steam boilers in electric generating plants in the United States have beenwelded with this electrode and its relative 9018CM.

Typical Mechanical Properties of Weld MetalStress-Relieved Stress-Relieved8 hrs. @1150°F. 8 hrs. @1350°F.


2332)"2( noitagnolE %1.977.06aerA fo noitcudeR %

Charpy V-Notch Impacts @30°F. 64 ft.-lbs. 127 ft-lbs.

Typical Chemical Composition of Weld MetalC Mn Si Ni Mo

0.06% 1.10% 0.40% 1.00% 0.50%

4.6.5 Atom Arc 8018W (AWS E8018-G) - The balanced alloy combination of chromium,nickel and copper of this electrode causes the weld metal to "weather" similarly to theweathering grade steels when exposed to the atmosphere. The inform color blend of this weldmetal with the weathered steel makes these electrodes the ideal choice when architecturalappearance and weld integrity is important.

Typical Mechanical Properties of Weld Metal Stress-RelievedAs Welded 1 hr. @1025°F.



Charpy V-Notch Impacts @-60°F. 63 ft-lbs. 44 ft.-lbs.


0.05% 1.11% 0.32% 1.70% 0.28%


LESSON IV

4.6.6 Atom Arc 9018CM (AWS E9018-B3) - These 2-1/4% chrome - 1% moly electrodesare used to weld and match the composition of the 2-1/4% chrome - 1% moly steels inpressure piping and power boilers. The chromium-molybdenum content of the weld metalhelps retain appreciable strength at temperatures up to 800°F.

Typical Mechanical Properties of Weld MetalStress-Relieved Stress-Relieved1 hr. @1275°F. 2 hrs. @1350°F.




0.05% 0.75% 0.60% 2.20% 1.05%

4.6.7 Atom Arc 9018-B3L (AWS E9018-B3L) - The low carbon content of this 2-1/4%chrome - 1% moly electrode makes the weld metal more crack resistant in heavy sections andallows lower preheat and interpass temperatures to be used. Typical applications include:high temperature power piping, boilers, heat-exchanger and condenser tubes, pressure vesselplates and steel castings for high temperature pressure service.

Typical Mechanical Properties of Weld MetalStress-Relieved Stress-Relieved8 hrs. @1150°F. 8 hrs. @1350°F.


4212)"2( noitagnolE %376.76aerA fo noitcudeR %

Charpy V-Notch Impact @30°F. 60 ft.-lbs. 79 ft.-lbs.


0.02% 0.74% 0.61% 2.47% 1.10%


LESSON IV

4.6.8 Atom Arc 10018 (AWS E10018-M) - The manganese-nickel-molybdenumcomposition of Atom Arc 10018 is used mostly on thinner sections of quenched and temperedlow alloy steels where 100,000 psi tensile strength, along with good ductility and toughness attemperatures as low as -60°F, are required. This product is used primarily for militaryapplications.



4242)"2( noitagnolE %765.36aerA fo noitcudeR %

Charpy V-Notch Impact @-60°F. 33 ft.-lbs. 22 ft.-lbs.


0.05% 1.58% 0.40% 1.50% 0.30%

4.6.9 Atom Arc 10018MM (AWS E10018-D2) - This electrode, with its combination ofmanganese and molybdenum, was originally developed during World War II to repair andfabricate manganese-molybdenum castings and armor plate. It is used to weld similarcomposition low alloy steels, as well as heat treatable steels comparable to hardenable steels.

Typical Mechanical Properties of Weld MetalStress-Relieved

As Welded 2 hrs. @1100°F.005,19000,101isp ,tnioP dleiY

Tensile Strength, psi 106,000 104,0006222)"2( noitagnolE %8615aerA fo noitcudeR %

Charpy V-Notch Impacts @72°F. 83 ft.-lbs. 73 ft.-lbs.@0°F. 55 ft.-lbs. 50 ft.-lbs.@-40°F. 38 ft.-lbs. 34 ft.-lbs.

Typical Chemical Composition of Weld MetalC Mn Si Mo

0.09% 1.77% 0.68% 0.35%


LESSON IV

4.6.10 Atom Arc 12018 (AWS E12018-M) - This electrode deposits high strength weldmetal in both the as welded and stress-relieved conditions, which is required for welding manyof the high strength quenched and tempered steels. It is used to weld steels with 120,000 psitensile strength in applications, such as welding carbon and high strength alloy steel forgingsfor railroad equipment, high strength steel castings for structural work, and steel castings forhighway bridges.




Charpy V-Notch Impacts @72°F. 52 ft.-lbs. 54 ft.-lbs.@-60°F. 32 ft.-lbs. 31 ft.-lbs.

Typical Chemical Composition of Weld MetalC Mn Si Cr Ni Mo

0.05% 1.90% 0.25% 0.85% 2.00% 0.50%

4.6.11 Atom Arc "T" (AWS E11018-M) - Atom Arc "T" electrodes were developed forwelding U.S. Steels T-1 steel, which is quenched and tempered to high strength and ductility. Ithas since been used to weld all of the quenched and tempered steels, including HY-80, thesteel used for the pressure hulls of nuclear submarines.

Typical Mechanical Properties of Weld MetalStress-Relieved

As Welded 1 hr. @1025°F.000,201000,301isp ,tnioP dleiY

1isp ,htgnertS elisneT 15,000 116,0004222)"2( noitagnolE %3626aerA fo noitcudeR %

Charpy V-Notch Impacts @72°F. 80 ft.-lbs. 73 ft.-lbs.@0°F. 55 ft.-lbs. 50 ft.-lbs.@-40°F. 48 ft.-lbs. 42 ft.-lbs.@-60°F. 41 ft.-lbs. 26 ft.-lbs.


LESSON IV


0.06% 1.53% 0.27% 0.31% 1.88% 0.43%

4.6.12 Atom Arc 9018HT (AWS E9018G) - As the HT indicates, this electrode is intendedfor heat treated applications. It deposits weld metal with properties that match chromium-molybdenum steel castings and is also useful in the repair and rebuilding of hot forging dies.

Typical Mechanical Properties of Weld MetalQuenched @1700°F. Quenched @1600°F.Tempered @1275°F. Tempered @900°F.


5.2102)"2( noitagnolE %725.75aerA fo noitcudeR %

Typical Chemical Composition of Weld MetalC Mn Si Cr Mo

0.14% 0.80% 0.65% 2.30% 1.00%

4.6.13 Atom Arc 4130 (No AWS Classification) - This composition was developed toweld heat treatable steels such as SAE4130, providing a weld metal that responds similarly tothe heat treatment.





0.18% 1.25% 0.40% 2.50% 1.28% 0.20%


LESSON IV

4.6.14 Atom Arc 4130 LN (No AWS Classification) - This alloy combination has lessthan 1% nickel so that it may be used safely to weld oil field equipment that handles "sour"(high sulfur) crude oil. The weld metal is hardenable by quenching and tempering similar toSAE4130 steel.





0.26% 1.25% 0.47% 0.49% 0.80% 0.16%

4.6.15 Additional information on Atom Arc Low Hydrogen, Low Alloy electrodes iscontained in the Atom Arc product catalog and the Atom Arc handbook for welding low alloyhigh tensile steels, published by ESAB.


LESSON IV

APPENDIX ASTICK ELECTRODE DATA CHARTS

ATOM ARC ELECTRODES

DEPOSITION EFFICIENCY DATA - LOW ALLOY, IRON POWDER ELECTRODESTYPES E7018, E8018, E9018, E10018, E11018, AND E12018

ELECTRODE DEPOSITION EFFICIENCY ELECTRODE DEPOSITION EFFICIENCYDIAMETER AMPS RATE lbs/hr % DIAMETER AMPS RATE lbs/hr %

3/32 70 1.37 70.50 3/16 200 4.85 76.4090 1.65 66.30 250 5.36 74.60110 1.73 64.40 300 5.61 70.30

1/8 120 2.58 71.60 7/32 250 6.50 75.00140 2.74 70.90 300 7.20 74.00160 2.99 68.10 350 7.40 73.00

5/32 140 3.11 75.00 1/4 300 7.72 78.00170 3.78 73.50 350 8.67 77.00200 4.31 73.00 400 9.04 74.00

CHART TO CONVERT ENGLISHELECTRODE DIMENSIONS TO METRIC

EQUIVALENTS

DIAMETER LENGTH

Inches mm Inches mm

3/32 2.4 12 3001/8 3.2 14 3505/32 4.0 14 3503/16 4.8 14/18 350/4507/32 5.6 18 4501/4 6.4 18 4505/16 8.0 18 450

STUB"LOSS CORRECTION TABLE FOR COATEDELECTRODE EFFICIENCY INCLUDING STUB LOSS

ELEC. DEPOSITION 2" 3" 4" 5"

LENGTH EFFICIENCY STUB STUB STUB STUB

60% 50.0% 45.0% 40.0% 35.0%65% 54.2% 48.7% 43.3% 37.9%

12" 70% 58.3% 52.5% 46.6% 40.8%75% 62.5% 56.2% 50.0% 43.7%80% 66.6% 60.0% 53.3% 46.6%60% 51.4% 47.1% 42.8% 38.5%65% 55.7% 51.1% 46.4% 41.8%

14" 70% 60.0% 55.0% 50.0% 45.0%75% 64.3% 58.9% 53.6% 48.2%80% 68.5% 62.8% 57.1% 51.4%60% 53.3% 50.0% 46.6% 43.3%65% 57.7% 54.2% 50.5% 46.9%

18" 70% 62.2% 58.3% 54.4% 50.5%75% 66.6% 62.5% 58.3% 54.2%80% 71.1% 66.6% 62.2% 57.7%


LESSON IV

APPENDIX BAPPENDIX BAPPENDIX BAPPENDIX BAPPENDIX B

LESSON IV - GLLESSON IV - GLLESSON IV - GLLESSON IV - GLLESSON IV - GLOSSAROSSAROSSAROSSAROSSARY OF Y OF Y OF Y OF Y OF TERMSTERMSTERMSTERMSTERMS

Quench - The rapid cooling of steel from a temperature above the transformationtemperature. This results in hardening of the steel.

Temper - Reheating of steel to a temperature below the transformation temperaturefollowing the quenching of steel. This usually lowers the hardness andstrength and increases the toughness of the steel.

StressRelieved - The reheating of a weldment to a temperature below the transformation

temperature and holding it for a specified period of time. A frequently usedtemperature and time is 1150°F. for 1 hr. per inch of thickness. Thisreheating removes most of the residual stresses put in the weldment by theheating and cooling during welding.

TransformationTemperature - The temperature at which the crystal structure of the steel changes,

usually about 1600°F.Heat AffectedZone - The area of the base metal that did not become molten in the welding

process, but did undergo a microstructure change as a result of the heatinduced into that area. If the HAZ in hardenable steels is cooled rapidly, thearea becomes excessively brittle.

UnderbeadCracking - A weld defect that starts in the heat affected zone and is caused by

excessive molecular hydrogen trapped in that region. It is sometimesreferred to as cold cracking, since it occurs after the weld metal has cooled.

Low HydrogenElectrodes - Stick electrodes that have coating ingredients that are very low in

hydrogen content. The low hydrogen level is achieved primarily by keepingthe moisture content of the coating to a bare minimum.

WeatheringSteel - Low alloy steel that is specially formulated to form a thin tightly adhering

layer of rust. This initial layer prevents further rusting and thus, the need topaint the steel is eliminated. The main alloys in this steel are copper andchromium.

ToeCracking - A weld defect that occurs at the toe of the weld metal. The cracking

occurs when the weld metal does not stretch with the base metal becausethe yield and tensile strength of the weld metal is greater than the steel.

Documents

ARC WELDING TECHNOLOGY - SharpSchoolwbsdeast.sharpschool.net/UserFiles/Servers/Server_2992254/File/Departments/Tech Ed...moisture testing chosen by ESAB is that described in Section