简介:Withthickplatesof2219high-strengthalloy,themicrostructuresofweldedjointswithtwinwireMIGweldingwereanalyzed.Experimentalresultsshowthatnohotcrackwasfoundintheweldduetodiscontinuousdistributionofcocrystallizationwithlowmeltingtemperature,butporosityisseriousinthefirstweldseamthatismainlycomposedofequiaxialgrainswithunevensizes.Asthepoorpositionofthewholeweldedjoint,fusionzonehasbigandcoarsegrains,unevenmicrostructures;Inquenchingzone,thereexistalotofsoakedmicrostructuresthatcocrystallizationwithlowmeltingtemperaturesoluteintomatrix,thusstrengtheningthemetalinthiszone;Inexcessiveagingzone,muchmorephasesthatdistributeevenlywillbeseparatedfromthematrix;Outsidethiszone,propertiesandmicrostructuresofthemetalarebasicallysimilartomatrixduetotherelativelylowtemperatureorunaffectedheatinthezoneduringwelding.
简介:ColdMetalTransfer(CMT)weldingtechniqueisanewweldingtechniqueintroducedbyFroniuscompany.CMTweldingofnickel-basedalloywithstainlesssteelwascarriedoutusingCuSi3fillerwireinthispaper.Effectsofweldingparameters,includingweldingcurrent,weldingspeed,etc,onweldsurfaceappearanceweretested.MicrostructureandmechanicalpropertiesofCMTweldwerestudied.Theresultsshowthatthethicknessofinterfacereactionlayerofthenickel-basedalloyis14.3μm,whichisonly4.33%ofbasematerial.Theweldismadeupoftwophases,α-copperandiron-basedsolidsolution.Ruptureoccursinitiallyattheweldedseamneartheedgeofstainlesssteelinsheartest.ThemaximumshearstrengthoftheCuSi3weldedjointis184.9MPa.
简介:Atypeofnovelinverterpowersupplysystemforhigh-powertwin-wirepulsedgasmetalarcwelding(GMAW)ispresentedmainlyfordealingwiththedisadvantagesoftheconventionalpowersupplyfortwin-wirepulsedGMAWofwhichtheoutputpowerisgenerallydifficulttoincreaseduetolimitationsofthepowerofsemiconductorsandthepowerdensityofmagneticdevices.Inthepowersuppliesforthemasterandslavearcs,thedigitalsignalprocessor(DSP)TMS320F28335isusedtoformtheDSP-basedsynergiccontrolsystemforparallelhigh-powerpulsedGMAW,whichachieveshigh-poweroutputoftwoparallelinverterscontrolledbyasingleDSP;master-slavecommunicationisachievedbyusingecontrollerareanetwork(eCAN)moduleofDSP,thusrealizinganti-phasepulseoutputofhigh-powertwin-wirepulsedGMAWandreducingtheinterferencebetweentwinarcs.Theexperimentresultsdemonstratethatthedesignedinverterpowersupplysystemforhigh-powertwin-wirepulsedGMAWcanbringabouthigh-powerefficiencyofwelding,stableweldingprocessandproperformationofwelds.
简介:Inthisstudy,theweldingthermalcyclecurveexhibitedtwotemperaturepeaksinhighheat-inputtwin-wireseparate-poolsubmerged-arcweldingandcoarse-grainedheataffectedzoneexistedintheweldedjoint.Theinclusionsofprimaryweldmetalandcoarse-grainedheataffectedzoneofCe-addedSAWshouldbeAl203,MnO,Si02,TiO,Ce2S3,CeS,Ce202SandCe203.Undertheeffectofweldingthermalcycle,oxy-sulfidesinclusionsofCe,thediameterofwhichwaslessthan2.0|Jim,slightlygrewlarger,butthecompositionandtypeoftheinclusionsdidn,tchange.ThemicrostructureofthelargeheatinputweldmetalhadacicularferritethatCeoxidesulphideparticlesinducednucleationandproeutectoidferrite.Inthecoarse-grainedheataffectedzoneofweldmetal,home-positionprecipitationofacicularferriteandsympatheticacicularferritewerebothobserved.Itwassupposedthatpreviouscrystalcellsofacicularferriteinaustenitegrainpromotedhome-positionprecipitationofacicularferrite.Meanwhile,sympatheticacicularferritetendedtonucleateattheprimaryacicularferritegrainboundaries,wherehighdislocationdensitywaslocated,andgrewinsidetheneighboringcarbon-depletedausteniticregions.Thegranularbainitenucleatedintheausteniticzonewithhighcarboncontentclosetoacicularferriteandsympatheticacicularferrite.