AWS PHB-7-1998 Everyday Pocket Handbook for Shielded Metal Arc Welding《手工电弧焊日用手册》.pdf

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1、1The EverydayPocket Handbookfor Shielded MetalArc Welding(SMAW)Compiled as a useful tool foron-the-job welding personnel by theAWS Product Development CommitteeNumber 7 in a series2NOTE: Although care was taken in choosing and presenting the data in this guide, AWS cannot guarantee that it iserror f

2、ree. Further, this guide is not intended to be an exhaustive treatment of the topic and therefore may not include allavailable information, including with respect to safety and health issues. By publishing this guide, AWS does not insureanyone using the information it contains against any liability

3、or injury to property or persons arising from that use. 1998 by American Welding Society. All rights reservedPrinted in the United States of America3Basic Safety Precautions .4AWS Specifications for Covered Electrodes 6Engineering Functions of SMAW ElectrodeCoatings 7Current Requirements for SMAW El

4、ectrodeClassifications.8Classification System for Carbon SteelElectrodes for SMAW.9Interpretation of Last Digit in AWS ElectrodeClassification 10Meaning of Suffix in Classification ofCarbon Steel and Low-Alloy Steel SMAWElectrodes .11Electrode Deposition Efficiency and StubLoss Factors 12Suggested A

5、mperage Ranges for Carbon Steeland Low-Alloy Steel Electrodes.13Deposition Rate, 5/32 in. Diameter CoveredElectrodes .14Typical Shielded Metal Arc ElectrodeOrientation and Welding Technique forCarbon Steel Electrodes . 15Suggested Amperage RangesAustenitic Stainless Steel (Type 3XX)Electrodes . 16Co

6、pper Alloy Electrodes. 16Nickel Alloy Steel Electrodes. 17Proper Care and Handling of SMAW Electrodes . 18Special Precautions for Low Hydrogen Electrodes. 20Guide to Conditioning and Storage ofSteel Electrodes 21Permissible Atmospheric Exposure ofLow-Hydrogen Electrodes . 22Suggested Joint Designs f

7、or SMAW Applications. 23Basic Welding Symbols and Their LocationSignificance 31Location of Elements of a Welding Symbol. 33Other Publications Available from AWS 34Table of Contents4Burn Protection. Molten metal, sparks, slag,and hot work surfaces are produced by welding,cutting, and allied processes

8、. These can causeburns if precautionary measures are not used.Workers should wear protective clothing madeof fire-resistant material. Pant cuffs, open pock-ets, or other places on clothing that can catchand retain molten metal or sparks should not beworn. High-top shoes or leather leggings andfire-r

9、esistant gloves should be worn. Pant legsshould be worn over the outside of high-topshoes. Helmets or hand shields that provide pro-tection for the face, neck, and ears, and a headcovering to protect the head should be used. Inaddition, appropriate eye protection should beused.Electrical Hazards. El

10、ectric shock can kill.However, it can be avoided. Live electrical partsshould not be touched. The manufacturersinstructions and recommended safe practicesshould be read and understood. Faulty installa-tion, improper grounding, and incorrect opera-tion and maintenance of electrical equipmentare all s

11、ources of danger.All electrical equipment and the workpieceshould be grounded. The workpiece lead isnot a ground lead. It is used only to completethe welding circuit. A separate connection isrequired to ground the workpiece. The work-piece should not be mistaken for a groundconnection.Basic Safety P

12、recautions5Fumes and Gases. Many welding, cutting,and allied processes produce fumes and gaseswhich may be harmful to health. Avoid breath-ing the air in the fume plume directly above thearc. Do not weld in a confined area without aventilation system. Use point-of-welding fumeremoval when welding ga

13、lvanized steel, zinc,lead, cadmium, chromium, manganese, brass, orbronze. Do not weld on piping or containersthat have held hazardous materials unless thecontainers have been inerted properly.Compressed Gas Cylinders. Keep caps oncylinders when not in use. Make sure that gascylinders are chained to

14、a wall or other struc-tural support.Radiation. Arc welding may produce ultra-violet, infrared, or light radiation. Always wearprotective clothing and eye protection to pro-tect the skin and eyes from radiation. Shieldothers from light radiation from your weldingoperation.Refer to AWS/ANSI Z49.1, Saf

15、ety in Welding,Cutting, and Allied Processes, for additionalinformation.6AWS Specifications for Covered ElectrodesType of Electrode AWS SpecificationCarbon steel A5.1Low alloy steel A5.5Corrosion resistant steel A5.4Cast iron A5.15Aluminum and aluminum alloys A5.3Copper and copper alloys A5.6Nickel

16、and nickel alloys A5.11Surfacing A5.13 and A5.217Engineering Functions of SMAW Electrode Coatings Promotes electrical conductivity by ionization of gases Produces shielding gas Adds slag formers for grain refinement Provides materials for controlling bead shape and width Provides alloy additions to

17、deposit Concentrates arc stream Imparts characteristics for welding position Insulates core wire8Current Requirements for SMAW Electrode ClassificationsElectrode Class CurrentEXX10 DCRPEXX11 AC or DCRPEXX13 AC or DC either polarityEXX15 DCRPEXX16 AC or DCRPEXX18 AC or DCRPEXX20 AC or DCSP (horizonta

18、l fillet)AC or DC either polarity (flat)EXX27 AC or DCSP (horizontal fillet)AC or DC either polarity (flat)9Classification System for Carbon Steel Electrodes for SMAWDesignates an electrode. This designator may be deleted from the product imprint required foridentification of the electrode.Designate

19、s the tensile strength (minimum), in ksi, of the weld metal when produced in accord-ance with the test assembly preparation procedure of this specification.Designates the welding position in which electrodes are usable, the type of covering, and thekind of welding current for which the electrodes ar

20、e suitable.EXXYY-1HZROptional Supplemental Designators:Designates that the electrode meets the requirements of the absorbed moisture test (anoptional supplemental test for all low hydrogen electrodes except the E7018M classification,for which the test is required).Designates that the electrode meets

21、 the requirements of the diffusible hydrogen test (anoptional supplemental test of the weld metal from low hydrogen electrodes, as-received orconditioned with an average value not exceeding “Z” mL of H2per 100g of depositedmetal, where “Z” is 4, 8, or 16).Designates that the electrode (E7016, E7018,

22、 or E7024) meets the requirements for improvedtoughness and ductility in the case of E7024.10Interpretation of Last Digit in AWS Electrode ClassificationLast Digt012345678Power supply Note a AC or DC reverse polarityAC or DC AC or DC AC or DC DCreverse polarityAC or DC reverse polarityAC or DC AC or

23、 DC reverse polarityType of slag Note b Organic Rutile Rutile Rutile Low HydrogenLow HydrogenMineral Low HydrogenType of arc penetrationDiggingNote cDiggingDeepMediumMediumSoftLightSoftLightMediumMediumMediumMediumSoftMediumMediumMediumIron powder in coating010% None 010% 010% 3050% None None 50% 30

24、50%a. E6010 is DC reverse polarity; E6020 is AC or DC.b. E6010 is organic; E-6020 is mineral.c. E6010 is deep penetration; E-6020 is medium penetration.11Meaning of Suffix in Classification of Carbon Steel and Low-Allow Steel SMAW ElectrodesSuffix MeaningA1 1/2% MolybdenumB1 1/2% Chromium, 1/2% Moly

25、bdenumB2 1-1/4% Chromium, 1/2% MolybdenumB2L Low Carbon version of B2 type (carbon content is 0.05% or less)B3 2-1/4% Chromium, 1% MolybdenumB3L Low Carbon version of B3 type (carbon content is 0.05% or less)B4L 2% Chromium, 1/2% Molybdenum, Low Carbon (0.05% or less)B5 1/2% Chromium, 1.1% Molybdenu

26、mC3 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 specificationsG Needs only a minimum of one of the elements listed in the AWS A5.5 table for chemical requirements12Electrode Deposition Efficie

27、ncy and Stub Loss Factors13ElectrodeDiameter(in.)Amperage (A)E6010 and E60113/321/85/323/167/325070100130140170160190190230E6012 1/85/323/167/321/4100130165200220240275320320380E6013 3/321/85/323/167/326075100135140180180220250290E7018 3/321/85/323/167/3270110120160150200200275250340E7024 1/85/323/1

28、67/321/4140180180240245290320360400450ElectrodeDiameter(in.)Amperage (A)Suggested Amperage Ranges for Carbon Steel and Low-Alloy Steel Electrodes14Deposition Rate, 5/32 in. Diameter Covered Electrodes15Typical Shielded Metal Arc Electrode Orientationand Welding Technique for Carbon Steel ElectrodesT

29、ype of JointPosition of WeldingWork Angle, DegreesTravel Angle, DegreesTechnique of WeldingGroove Flat 90 510* BackhandGroove Horizontal 80100 510 BackhandGroove Vertical-Up 90 510 ForehandGroove Overhead 90 510 BackhandFillet Horizontal 45 510* BackhandFillet Vertical-Up 3555 510 ForehandFillet Ove

30、rhead 3045 510 Backhand*Travel angle may be 10 to 30 for electrodes with heavy iron powder coatings.16Suggested Amperage Ranges for Austenitic Stainless Steel (Type 3XX) ElectrodesElectrodeDiameter(in.)Amperage (A)E3XX-15 and E3XX-163/321/85/323/161/440855512085165100210205290Suggested Amperage Rang

31、es forCopper Alloy ElectrodesElectrodeDiameter(in.)Amperage (A)ECuNi 3/321/85/323/16659580125105190150225ECuAl-A2 3/321/85/323/161/4608010012013015017019023525517ElectrodeDiameter(in.)Amperage (A)ENiCrFe-3 3/321/85/323/16558080110110140130170Suggested Amperage Ranges for Nickel Alloy Steel Electrode

32、sENiCu-7 3/321/85/323/16558080110110140130170ElectrodeDiameter(in.)Amperage (A)The electrical resistivity of the core wire in these electrodes is exceptionally high. For this reason, excessive amperage will overheat the electrode and damage the covering, causing arc instability and unacceptable amou

33、nts of splatter. Each classifica-tion and size of electrode has an optimum amperage range.18To ensure satisfactory weld quality, it is importantthat the SMAW electrodes be handled and storedproperly prior to use. The coatings of the electrodeshave been carefully designed to provide the neces-sary op

34、erating characteristics and weld propertiesrequired for each of the types of electrodes.The electrode coatings are subject to damage fromimproper handling and storage practices. The coat-ings can crack and may fall from the electrode corewhen experiencing impact loads. This condition canbe the resul

35、t of dropping the electrode packages dur-ing transportation of the materials to the job site or byhitting the packages with another object while in stor-age or during material movement. It is the responsi-bility of the welder to inspect the electrodes prior touse to ensure that the coating is intact

36、 and does notshow indications of damage.The electrode coatings are also hygroscopic, meaningthat they are susceptible to absorbing moisture whenexposed to the atmosphere. Moisture pick-up in thecoating can result in porosity, less than optimum arccharacteristics and hydrogen induced cracking. Theele

37、ctrodes can become exposed to moisture condi-tions if improperly stored or if the packagingbecomes damaged during shipping or handling.It is the responsibility of the welders to protect theelectrodes while in their possession. For example,in foggy, misty, and rainy weather, or in conditionsof high h

38、umidity, the electrodes should be kept in aclosed container to prevent direct exposure of thematerials to the weather conditions. It is alsoimperative that the electrodes not be kept or carriedin the pockets of a welder, as exposure to perspira-tion or other body moisture may cause the coatingProper

39、 Care and Handling of SMAW Electrodes19to introduce excessive amounts of water into theweld.The recommendations contained in this pocket hand-book represent good welding practices. Many weld-ing codes have specific requirements for handlingelectrodes and for the time of electrode exposure inthe atmo

40、sphere during the welding operation. Thefabricator is responsible for ensuring that the neces-sary code requirements are fulfilled for each job.The electrode manufacturer will have recommen-dations for processing their products. Valuableinformation can be obtained from the manufacturersfor handling,

41、 using, and reconditioning SMAWelectrodes.20Hydrogen can have adverse effects on welds in somesteels under certain conditions. One source of thishydrogen is moisture in the electrode coverings. Forthis reason, the proper storage, treatment, and han-dling of electrodes are necessary.Electrodes are ma

42、nufactured to be within acceptablemoisture limits, consistent with the type of coveringand strength of the weld metal. They are normallypackaged in a container which has been designed toprovide the degree of moisture protection considerednecessary for the type of covering involved.If there is a poss

43、ibility that the noncellulosic elec-trodes may have absorbed excessive moisture, theymay be restored by rebaking. Some electrodesrequire rebaking at a temperature as high as 800F(425C) for approximately 1 to 2 hours. The mannerin which the electrodes have been produced and therelative humidity and t

44、emperature conditions underwhich the electrodes are stored determines the properlength of time and temperature used for recondition-ing. Some typical storage and drying conditions areincluded in the table on page 21.Low hydrogen electrodes will adsorb, and possiblyabsorb, excessive moisture in the c

45、oatings whenexposed to the atmosphere. Fabrication standardssometimes specify the time limits for exposure to theatmosphere that may be permitted before the elec-trodes must be redried or otherwise processed prior touse on a job.Not all coated electrodes are treated the same. Forexample, cellulosic

46、coverings for E6010 and E6011electrodes need moisture levels of 3% to 7% forproper operation. Therefore, storage or conditioningabove ambient temperature may dry them too muchand adversely affect their operation.Special Precautions for Low-Hydrogen Electrodes21Guide to Conditioning and Storage of St

47、eel ElectrodesAWS Electrode ClassificationAir ConditionedStorage Before OpeningRH = Relative HumidityHolding Temperature After OpeningReconditioning Temperature andTime to Affect Weld QualityRecondition Step #1 Rebake Step #2EXX10, EXX11, EXX12, EXX13Keep Dry RoomTemperature 40120F60% (10%) RH100F (

48、25) Not RequiredNEVER STORE ABOVE 130 OR BELOW 50% RHNot RequiredEXX20, EXX30Iron PowderEXX14, EXX24, EXX2790F (20)50% Max. RH150200F 250300FONE HOUR350F (25)ONE HOURTWO HOUR TOTALIron PowderLow HydrogenEXX18, EXX28Low HydrogenEXX15, EXX1690F (20)50% Max. RH300F (50) 500600FONE HOUR700F (50)ONE-HALF

49、 HOURONE & ONE-HALF HOUR TOTALLow HydrogenHigh TensileEXXX15, EXXX16, EXXX1890F (20)50% Max. RH300F (50) 500600FONE HOUR650F (50)ONE-HALF HOURONE & ONE-HALF HOUR TOTAL22(Permissible Atmospheric Exposure of Low-Hydrogen ElectrodesElectrode Column A (hours) Column B (hours)A5.1E70XXE70XXRE70XXHZRE7018M4 max9 max9 max9 maxOver 4 to 10 maxA5.5E70XX-XE80XX-XE90XX-XE100XX-XE110XX-X4 max2 max1 max1/2 max1/2 maxOver 4 to 10 maxOver 2 to 10 maxOver 1 to 5 maxOver 1/2 to 4 maxO