分析铸钢及高合金铸钢焊接.pdf

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1、STEELCASTINGSHANDBOOKSupplement7WeldingofHighAlloyCastingsSteelFounders'SocietyofAmerica2004WeldingofhighalloysteelcastingsbyE.A.SchoeferConsultantSteelFounders’SocietyofAmericaEditedbyM.BlairSteelFounders’SocietyofAmerica1.IntroductionIron-baseandnickel-basehighalloys-bydefinitionthosecontainingeig

2、htpercentormoreofanotherelement-arewidelyusedforconstructionofindustrialprocessequipmentthatmustresistthedeterioratingeffectofacorrosiveofhightemperatureenvironment.Bothwroughtandcastformsofsuchalloysmaybeweldedduringthemanufactureoffinishedcomponentssotheweldabilityofthealloysoftenisamatterofconcer

3、ntotheuser.Thesameweldingprocessesareappliedtowroughtandcastproductsand,ingeneral,similartechniquesandpracticesareemployed.Differencesbetweenwroughtandcastalloysinchemicalcompositionandmicrostructure,however,influencetheweldingcharacteristicsofeachformandmustbegivenconsideration.Inaddition,thehighal

4、loysdiffermarkedlyfromcarbonandlowalloysteelsinphysicalpropertiessuchaselectricalresistance,thermalexpansionandthermalconductivity.Itisessential,therefore,toemployproceduresallowingforallthesefactorswhenweldinghighalloycastings.1.1Allthecastingalloyshaveequalorbetterweldabilitythanthecorrespondingwr

5、oughtalloys,buttherearevariationsfromgradetogradeintheeasewithwhichsatisfactoryweldsareobtained.Thelow-carbon,austeniticgradesusuallyareconsideredeasiertoweldthanhigh-carbonausteniticorstraight-chromiumferriticormartensitictypes.Nevertheless,eachofthestandardalloycompositionscanbeweldedsuccessfullyi

6、nthefoundry.UsinginformationderivedfromtheextensiveresearchofAlloyCastingInstituteandSteelFounders’SocietyofAmerica,thefoundrymanoftenisabletotailorthecompositionbalanceespeciallytoprovidetheoptimumweldability.Accordingly,castingsarereadilyweldedintofabricatedstructuresandweldingisconsideredaregular

7、partofthefoundryproductionprocess.1.2Weldingisusedaprocedureforupgradingcastingqualityduringthecourseofmanufacturethroughimprovementofsurfaceconditions,orbyeliminationofshrinkagevoids.Itisalsousedforp