简介:ThesusceptibilityofweldedjointfortheX65pipelinesteeltoH2Sstresscorrosioncracking(SCC)isinvestigated.SCCtestsonthesteelarecarriedoutintheenvironmentbasedonNACETM-01-77solutionwithsaturatedgaseousH2S.Thethresholdstressintensityfactorandcrackpropagationvelocityarecalculatedaccordingtowedge-openingloading(WOL)specimens.Thethree-dimensionalelastic-plasticfiniteelementanalysisofWOLspecimensisperformedbyusingtheFEMprogrammingpackageANSYS.Stressfieldandconcentrationofhydrogendistributionpropertyaheadofthecracktipareobtained.ThispapersurveyedthemicrostructureofweldedjointandstudiedonthemechanicalpropertiesofX65pipelinesteel.Itprovidesexperimentalbasisforstudyingstresscorrosion.Theresultsofnumericalanalysisareconsistentwithconclusionsofstresscorrosiontest.
简介:Theeffectofnonmetallicinclusionsinthedropletofthestainlesssteelcoveredelectrodeontheporositywasresearched.Theresultshowsthatthenonmetallicinclusionsinthedropletarespherical,theircompositionisdifferentfromtheoneofslagandtheinclusionshavethecharacterof"innerformation".Whentheratioofrutiletoilmeniteinthecoatedmaterialisincreased,thedropletbecomescoarse,thecontentofnonmetallicinclusioninthedropletdecreases,andtheporositysensitivityintheweldmetalalsodecreases.Whentheratiooffledspartoilmeniteinthecoatedmaterialisincreased,thedropletbecomesfine,thecontentofnonmetallicinclusioninthedropletincreases,andtheporositysensitivityintheweldmetalincreases.WhentheratioofFe2O3toilmeniteinthecoatedmaterialisincreased,thedropletbecomesfine,thecontentofnonmetallicinclusiondecreases,whiletheporositysensitivitydoesnotreduce.
简介:WeldingresearchofA6N01S-T5aluminumalloyprofileforhigh-speedtrainwasdonebyusinglaser-MIGhybridweldingandMIGweldingindividually.Andtheweldappearance,weldingdistortion,mechanicalpropertiesofthejointsandmicrostructureswereanalyzed.Thetestresultsdemonstratedthathigh-efficientweldingfortheprofilecanbeachievedbyusinglaser-MIGhybridwelding,thespeedofwhichcanbeover3.0m/min.Theprocessinghadagoodgapbridgingability,evenifthegapofthebuttjointwasupto2.0mm,agoodweldappearancecanalsobegot.Whilethehybridweldingspeedwasgreaterthan2.5m/min,theweldingdistortionofthelaser-tandemMIGhybridjointswasjustabout33%ofthatoftheMIGjoints,buttheweldingefficiencywasover3timesofMIGwelding.Andtensilestrengthofthehybridjointswas85%ofthatofA6N01S-T5basemetal,9%higherthanthatoftheMIGjoints.Fatiguepropertieswastestedindividuallywithpulsedtensilefatiguemethodintheconditionof1×107lifetime.Thetestresultsdemonstratedthatthefatiguestrengthofthejointswasalittlelowerthanthatofbasematerial,whichcouldbeupto115MPa.Butthefatiguestrengthofhybridweldingjointswas107.5MPa,whichwas23%higherthan87MPaofMIGweldingjoints.
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.