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简介：Consideringthelimitationofcomputationalcapacity,anewfiniteelementsolutionisusedtosimulatetheweldingdeformationofthesidesillofrailroadcar'sbogieframebasedonthelocal-globalmethod.Firstly,avolumetricheatsourcedefinedbyadoubleellipsoidisadoptedtosimulatethethermaldistributionsofthearcweldingprocess.Andthen,thelocalmodelsextractedfromtheglobalmodelarecomputedwithrefinedmeshes.Onthesebases,theglobaldistortionsofthesubjectstudiedareascertainedbytransferringtheinnerforcesofcomputedlocalmodelstotheglobalmodel.Itindicatesthatthelocal-globalmethodisfeasibleforsimulatingthelargeweldedstructuresbycomparingthecomputedresultswiththecorrespondingactualmeasuredvalues.Theworkprovidesbasisforoptimizingtheweldingsequenceandclampingconditions,andhastheoreticalvaluesandengineeringsignificanceintheintegraldesign,manufacturingtechniqueselectionofthebogieframe,aswellasotherkindsoflargeweldedstructures.

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简介：Agroupofprojectionweldingexperimentsandjointstension-sheartestsarecarriedoutforcold-rolledsteelsheets,galvanizedsteelsheets(GSS)withouttreatment,GSSwithphosphatingandGSSwithsurfacegreasing,respectively.Theexperimentalresultsareregressivelyanalyzedonthecomputers,thentheprojectionweldedjointtension-shearstrengthcurveandtheperfectweldingcurrentsrangeofeachmaterialareobtained.Theresultsshowthatsurfacetreatmentsofgalvanizedsteelshaveeffectsontheirspotweldabilities.Amongthefourkindsofmaterials,GSSwithsurfacegreasinghavetheworstspotweldability,fortheyneedhigherweldingcurrentandhaveanarrowweldingcurrentrange.

简介：Asadepositiontechnology,gasmetalarcwelding(GMAW)hasshownnewpromiseforrapidprototypingofmetallicparts.DuringtheprocessofmetalformingusingthearcofGMAW,lowheatinputandstabledroplettransitionarecriticaltohighqualityfiguration.TheeffectsofvariousprocessingparametersonfigurationqualitywerestudiedintheexperimentofGMAWrapidprototypingusingthewireofER50-6,includingweldingvoltage,wirefeedingrate,weldingspeedandsoon.TheoptimalparametersforER50-6areobtained.Simultaneously,itisverifiedthattherapidprototypingpartswithfavorablestructuresandqualitycanbeachievedundertheconditionsoflowheatinputandstabledroplettransition.

简介：ＥｆｆｅｃｔｓｏｆｓｔｒｅｎｇｔｈｍａｔｃｈｉｎｇａｎｄｃｒａｃｋｄｅｐｔｈｏｎｔｈｅｆｒａｃｔｕｒｅｐａｒａｍｅｔｅｒｓｆｏｒｗｅｌｄｅｄｊｏｉｎｔｓＴａｎｇＷｅｉａｎｄＳｈｉＹａｏｗｕ（Ｘｉ＇ａｎＪｉａｏｔｏｎｇＵｎｉｖｅｒｓｉｔｙ）Ａｂｓｔｒａ...

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简介：Theresistancespotweldingof6063-716aluminumalloyandl6Mnsteelwasstudiedbynuggetalloying.TheresultsindicatedthattheAl-steeljointhadcharacteristicsofwelding-brazing.Thenuggetzoneconsistedmainlyofα-AlsolidsolutionwithdislocationsandfineMg_2Siparticles.Theinterfacezonehadadouble-layerstructure:Fe_2Al_5layeratsteelsideandFe_4Al_(13)layeratAlnuggetside.Thenuggetalloyinghasasignificanteffectonthejointpropertiesbychangingphasecompositionandrefinementofgrains.WhenalloyelementsCu,Zn,TiandNiwereadded,thetensileshearloadofAl-steeljointsreached2780N,2910N,2915Nand2929Nrespectively,whichincreasedby24.1%,29.9%,30.1%and30.7%respectivelycomparedwiththat(2241N)ofjointwithoutnuggetalloying.Therefore,itisaneffectivewayforimprovingmechanicalpropertiesofresistancespotweldedAl-steeljoints.

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简介：Forthedevelopmentofalow-melting-pointfillermetalforbrazingaluminumalloys,aseriesofAl-Si-Cu-(Ni,Sn,Zn)fillermetalshavebeenstudied.Throughdifferentialthermalanalysis(DTA),themeltingtemperaturesofsuchAl-Si-Cu-(Ni,Sn,Zn)fillermetalsweredetermined.Theresultsshowthattheadditionof3wt.%-5wt.%SnintotheAl-6Si-15Cufillermetalcausesitssolidustemperaturetodecreasebyabout12℃.ThefillermetalwiththecompositionAl-6Si-l5Cu-2Niisproposed,whichpossessesameltingtemperaturerangeof512℃to520℃andamicrostructarethatincludesanAl-Cueutecticphases,Al-Si-Cueutecticphases,siliconparticlesandCu_2Al,AlNi_3,Al_7Cu_4NiandAl_3Ni_2intermetalliccompounds.Anadditionof5wt.%-7wt.%ZnintosuchAl-Si-Cufillermetalscausetheirsolidustemperaturestodropfurthertoavaluelowerthan498℃.MetallographicobservationsindicatethattheadditionofZnintotheAl-Si-CufillermetalinhibitstheformationoftheAl-Si,Al-CuandAl-Si-Cueutecticphases.TheremainingphasesareaAl_2Cuintermetalliecompound,anα-Alsolidsolutionandsiliconparticles.

简介：Thecharacteristicsoftemperatures,stressesandstrainsfieldshavebeenstudiednumericallyforatitaniumalloysheetweldedwithanimprovedgastungstenarcweldingmethod,inwhichatrailingspotheatsinkisintroducedtocontroltheweldingstressanddistortion.Theimpingingjetmodelisemployedtodescribetheintenseheattransferbetweenthecoolingmediaandthetopsurfaceoftheworkpiece.Theinfluenceofthedistancebetweenarcandheatsinkisinvestigated.Resultsshowthatthereisanidealrangeofdistance.Usingtheidealdistance,alowstressandnodistortionweldingstructurecanbederived.

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简介：EffectsofalloyelementsonthemicrostructureandcrackresistanceofFe-C-Crweldsurfacinglayerwereinvestigated.Theresultsshowthatmicrostructuresofthelayermainlyconsistofcarbidesandaustenitematrix.IncreasingCandCrcontentsimpairthecrackresistanceofthelayerduetoincreasedamountofbrittlecarbides.TheadditionofNi,NborMoimprovesthecrackresistanceofFe-C-CrweldsurfacinglayerbyincreasingtheamountofausteniteandformingfineNbCorM7C3carbidesinthelayer.But,theexcessiveNb(>2.50wt%)orMo(>1.88wt%)impairsthecrackresistanceofthelayer,whichhasrelationwithincreasedcarbidesorcarbidecoarseningandaustenitematrixsolidsolutionstrengthening.ThepropercombinationofC,Cr,Ni,NbandMocanfurtherimprovenotonlythecrackresistanceofFe-C-CrweldsurfacinglayerbutalsotheerosionresistanceasaresultoffineNbCandM7C3carbidesdistributinguniformlyinaustenitematrix.Theoptimallayercompositionsare3.05wt%C,20.58wt%Cr,1.75wt%Ni,2.00wt%Nband1.88wt%Mo.

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