简介:ThediffusionbondingofAZ3\BMgalloyandQ235steelwasinvestigatedwithaZn-5AIalloyasinterlayerandunderdifferentholdingtimerangingfrom3to1200s.Themicrostructureandphasecompositionsofbondedjointswerecharacterizedbyscanningelectronmicroscopy(SEM),energydispersivespectrometer(EDS)andX-raydiffraction(XRD)methods.TheshearstrengthofMgalloy/steeljointswasmeasuredbytensiletester.Itwasfoundthatthemicrostructureofbondedjointsevolveddramaticallyalongwiththeprolongationofholdingtime.Undertheholdingtimeof3s,themainpartofjointwascomposedofMgZn2phaseanddispersedAl-richsolidsolutionparticles.Whenincreasedtheholdingtimemorethan60s,theexcessivesolutionofAZ3\Bintotheinterfacialreactionarealedtotheformationofcoarsephaseandeutecticmicrostructure,andalsothecomplexFe-AlandMg-Al-ZnIMCsattransitionlayerclosedtoQ235steelside.Accordingtothetensiletestingcharacterizations,thejointsobtainedunderholdingtimeof3sexhibitedthebestshearstrengthof84MPa,andthefractureoccurredattheintermediarypartofjointwheretheflexibleAl-richsolidsolutionparticlescouldhelptoimpedethemicrocrackpropagations.Withprolongingtheholdingtimeto600s,theshearstrengthofjointswasdeterioratedenormouslyandthefracturepositionwasshiftedtothetransitionlayerpartclosedtoQ235steel.
简介:ThevacuuminductionbrazingofSiCparticulatereinforcedLY12alloymatrixcompositeusingAl-28Cu-5Si-2Mgfillermetalhasbeencarriedout.Themicrographofthejointinterfacewasobservedbyscanningelectronmicroscopy.Thejointstrengthwasdeterminedbysheartests.Theresultsshowthatbrazingtemperature,holdingtime,SiCparticlevolumepercentageandpostheattreatmentinfluencejointstrength.SiCparticleshappeninthebrazingseamandthedistributionofSiCparticlesinthejointisnotuniform.Particle-poorzonesinthejointexistnearthebasemetal,andparticleconcentratezonesexistinthecenterofthebrazingseam.Inaddition,thefailureofthecompositeispredominantlyinitiatedbytherootingofSiCparticleinthebrazingseamandthemicro-crackexpandedalongthebrazingseamwithlowenergy.
简介:BondingofAl2O3tocuisperformeddirectlyusingTifoilattemperatureof1273K.Themicrostructureofthejointinterfaceisinuestigatedthroughscanningelectronmicroscope(SEM),electron.probemicroanalysis(EPMA)andX-raydiffraction(XRD).theeffectoftheinitialtifoilthicknessonthereactionlayerthicknessandthejointStrengthareinvestigated.
简介:IntheautomaticCO2arcwelding,thealterationoftheverticaldistancebetweentheweldingtorchandtheworkpiecehasastrongeffectontheweldingparameterssuchasweldingcurrentandvoltage,withtheresultthattheappearanceandqualityofweldarenotsteady.Toweakentheinfluenceofthedistancealteration,amethodisputforwardinthepaper.Themethodisthatthealternatewire-feedcontrolisusedforcompensatingtheweldingcurrent.Onthebasisoftheoreticalanalysis,astaticnumericalmodelforalternatewire-feedcontrolisestablished.Theexperimentsshowthatthemodel-basedregulationofthewirefeedratecancompensatetheweldingcurrentandensuretheappearanceofweld.Whenthealterationofverticaldistancebetweenthetorchandtheworkpieceisgreater,notonlyisthewirefeedrateregulated,buttheoutputvoltageofthepowersourceisadjustedtoensuretheappearanceandqualityofweld.
简介:ThispaperintroducesabrazingprocessbetweenAl_2O_3ceramicandInvaralloy.Al_2O_3canbebrazedwithInvareffectively.TheinterfacialstructureofAl_2O_3/Invarjointcanbeexpressedas:Invar/Ag(s,s)+Cu(s,s)+Fe_2Ti(zoneⅠ)/Ag(s,s)+Cu(s,s)+Fe_2Ti+NiTi+Cu_3Ti(zoneⅡ)/Ag(s,s)+Cu(s,s)+Cu_2Ti+Al(s,s)+TiC+TiO(zoneⅢ)/Al_2O_3.Themaximumshearstrengthof139MPawasmeasuredforas-brazedAl_2O_3/Invarjointbrazedat850℃for25minor900℃for15min.
简介:AnewkindofsimpleandflexibleCO_2weldingsystemwasdevelopedtocarryoutwaveformcontrol.ThesystemconsistedofIGBTinverter,PWMcircuitandmicroprocessorunit(MPU),inwhichtheoutputcurrentofconstantcurrent(CC)powersupplycouldbechangedaccordingtotransientphysicalstate,andthevariabledownsloperatecontrolcouldbeusedtoensureastableweldingprocess.Theweldingexperimentresultsprovedtheeffectivenessofthiscontrolapproach.
简介:Theeffectsoftwopost-weldheattreatmentprocessesonthemicrostructureandfatiguepropertiesoftheelectronbeamweldedjointsof30CrMnSiNi2Asteelwerestudied.Electronbeamlocalpost-weldheattreatment(EBLPWHT),inavacuumchamber,immediatelyafterweldingandatraditionalfurnacewholepost-weldheattreatment(FWPWHT)wereaccepted.Theexperimentalresultsshowthat,afterEBLPWHT,themainmicrostructureofweldischangedfromcoarseacicularmartensiteintolathmartensite,andbasemetalischangedfromferriteandperliteintoupperbainiteandresidualaustenite,howeverthemicrostructuresofdifferentzonesofjointsinFWPWHTconditionsaretemperedsorbite.Thefatiguecrackgrowthrateda/dNofweldsandbasemetalarenotobviouslychangedamongEBLPWHT,FWPWHTtestandas-welded(AW)test,asthemechanicalpropertiesofmaterialshaveacertainbutnotlargeeffectontheda/dNofweldedjoints.TheresistancetonearthresholdfatiguecrackgrowthdataofweldedjointscanbelargelyimprovedbyEBLPWHTanditisrelatedtomicrostructureandcrackclosureeffect.
简介:AnewsimulationmodelofCO2short-circuitingtransferweldingmaybeemployedtodevelopanewpatternofweldingmachineandtopredictweldingprocessparameterstoobtaintheoptimumweldingtechnologyproperties.Inthispaper,anewsimulatingmodelisdevelopedaccordingtotheAWP(adaptingweldingphysicsprocess)waveformcontrolmethod.Goodagreementisshownbetweenthepredictedandexperimentallydeterminedresults.ThemodelwillmakeanimportantpromotioninthedevelopmentofCO2arcweldingtechnique.
简介:Anewhardfacingprocess,reactivebrazecoatingprocess(RBCC)wasstudied,and(TiC+Cr3C2)/FecompositecoatingswerepreparedbyRBCCusingcarbon,Cr3C2,iron,ferrochromiumandtitaniumpowderastherawmaterialsinvacuumbrazefurnace.TheresultsshowthatTiCisin-situsynthesizedinthecoatings.ThemethodsofintroducingCr3C2havegreateffectsonthedistributionofTiC.AddingCr3C2directlytotherawmaterialsforcoatings,fineTiCparticlesaggregateintodiscoidsparalleltothecoatingsurface,whereas,in-situsynthesizingCr3C2incoatings,theaggregationsofTiCarelumpish.Duringbrazecoating,Cr3C2particlesdirectlyaddeddissolveandprecipitatetobecomeneedle-shaped.Thecoatingshaveanevenandsmoothsurfaceandarecombinedwiththeirmildsteelsubstratesbyametallurgicalbonding.
简介:Laserblankweldingisbecomingmoreandmoreimportantintheautomotiveindustryandthequalityoftheweldiscriticalforasuccessfulapplication.Afullyautomatedsolutionisrequiredtoinspectthequalityoftheblanks.ThispaperpresentsavisioninspectionsystemwithaCMOScamerawhichusesART2networktoinspectthedefectson-linetoobtainthegeometryandthequalityoftheweldseam.TheneuralnetworkART2hasthecapabilityofself-learningfromtheenvironment.Itcandistinguishthedefectsthathavebeenlearnedbeforeandgivenewoutputsfornewdefects.SoART2networkissuitableforweldqualityinspectioninlaserblankwelding.Additionally,aCO_2laserisusedfortheblankbutt-welding.