铝车身焊接技术培训

©2015RLEINTERNATIONALGroup1IRLEINTERNATIONAL睿力汽车科技BodyTeamTrainingSeries–Lesson1Material-AluminumJuly2017©2015RLEINTERNATIONALGroup2IContentApplicationsinBIWMaterialCharacteristicsAlloyConstitutionBriefIntroductionTrainingContent©2015RLEINTERNATIONALGroup3IBriefIntroduction©2015RLEINTERNATIONALGroup4IBriefIntroduction–AluminumElementAtabout8%oftheearth'scrust,aluminumisthemostabundantmetal.Nowadaysaviation,construction,automotivethesethreemajorindustriesrequiresmaterialpropertieswiththeuniquepropertiesofaluminumanditsalloys,whichgreatlybeneficialtotheproductionandapplicationofaluminum.Itsapplicationisextremelyextensive.©2015RLEINTERNATIONALGroup5IBriefIntroduction-HistoryaboutAluminumBefore19thcentury,aluminumisregardedasararepreciousmetal,evenbemoreexpensivethangold.TheFrenchemperorNapoleonIIIevenorderedofficialstobuildaaluminumcrowntoshowhiswealthandpower.Withthedevelopmentofelectrolyticalreductionprocess,aluminummetalproductionstartedtogrowrapidly.Theelectrolyticalreductionprocesswasdevelopedandpatentedin1886simultaneouslyandindependentlybyPaulHéroultinFranceandCharlesMartinHallintheUS.©2015RLEINTERNATIONALGroup6IBriefIntroduction-ElectrolyticalReductionProcessAluminummetalisobtainedfromaluminabyelectrolyticreduction,usingtheHall-Héroultprocess.CalcinedAl2O3isreducedtoaluminummetalinelectrolyticcells,or“pots”,connectedinseriestoaDCpowersource.Thecellsarerectangularsteelpotslinedwithrefractorybricksandcarbon.Modernsmelters(figuresbelow)containtypicallyseveralhundredscells(432forthesmelterpictured),operatingatcurrentsof150,000to300,000amperes.Newtechnologyiscomingon-linethatoperatesat500,000amperes.©2015RLEINTERNATIONALGroup7IBriefIntroduction-ElectrolyticalReductionProcessIttakesapprox2tonesofaluminatoproduce1toneofaluminummetal.Typicalpurityofthemetalproducedis99.7%,withironandsiliconasprincipalimpurities.©2015RLEINTERNATIONALGroup8IAlloyConstitution©2015RLEINTERNATIONALGroup9IAlloyConstitution–MainReasonofAlloyingPlasticdeformationofmetalsisduetotheexistenceoflinearlatticedefects-thedislocations.Plasticdeformationproceedsbymovementandmultipli-cationofdislocations(seefigurebelow).Strengtheningoccurswhenobstaclesfordislocationmovementareintroducedintothelattice.YieldStrength:lessthan20MpaTensileElongation:morethan40%99.8%purealuminumStrengtheningEffectsForStructuralApplication©2015RLEINTERNATIONALGroup10IAlloyConstitution–AlloyElementsUnalloyed,purealuminumisverysoftandductile.Forstructuralandotherusesalloyingelementsareaddedtoimpartdesiredproperties,suchasstrength,toughness,corrosionresistanceandphysicalproperties.•Majoralloyingelements-arespeciallyaddedtothealloytointroducecertainspecificproperties(solidsolutionstrengthening,strainhardening,precipitationoragehardening,easeofcastingetc.)duringuse.•Minoralloyingadditions-usuallythosewithlowsolidsolubilityformcoarseandfineintermetallicphasesandindirectlyaffectproperties,e.g.bygrainrefiningduringcastingorheattreatments.©2015RLEINTERNATIONALGroup11IAlloyConstitution–StrengtheningMechanismsInaluminumthreebasicstrengtheningmechanismsareeffective.TheseareclassifiedasWorkStrengthening,SolidSolutionStrengtheningandPrecipitationStrengthening.➢WorkStrengtheningItiseffectiveforbothpurealuminumandaluminumalloy.Bycolddeformation,densityofdislocationwillincreaseanddislocationswillintertwine.Itwillblockdislocationslip.Material’sstrengthandhardnessincrease,buttheelasticitydecreases.©2015RLEINTERNATIONALGroup12IAlloyConstitution–StrengtheningMechanisms➢SolidSolutionStrengtheningAlloyingelementsinsolidsolutioninteractwithdislocationsmainlybylocalstressfieldsprovidingadditionalfrictionforcesduringdislocationmovement.Thisstrengtheningmechanismincreasestheeffectofworkhardening.3XXXand5XXXalloysaretypicalexamplesofsolidsolutionhardenedalloys.©2015RLEINTERNATIONALGroup13IAlloyConstitution–StrengtheningMechanisms➢PrecipitationStrengtheningPrecipitatesofsecondaryphasesinaluminumareveryeffectiveobstaclesfordislocationsdependingonsizeanddistance.Smallcoherentprecipitatesmaybecutbydislocations.Withgrowingsizeand/orlossofcoherencywithinthelatticestructuretheobstaclestrengthofaprecipitateparticleincreases.Duringtheprocess,thehardnesswillincrease.©2015RLEINTERNATIONALGroup14IAlloyConstitution–StrengtheningofAlloyElementsAlloyingelementsareaddedinAlfordifferentpurposes:➢SiisaddedtoimprovethefluidityofmoltenAl➢Ti(onitsownorasTiB2orTiCgrainrefiners)areaddedtoimprovecastability.➢Mostotherelementsareaddedtoimprovestrengthofthefinalproductindifferentways.ThefiguresbelowshowtheeffectofstrengtheningofdifferentalloyingelementsinsuperpurebinaryAlalloys.©2015RLEINTERNATIONALGroup15IAlloyConstitution–CastingAluminum&WroughtAluminumAluminumAlloyCastingAluminumWroughtAluminumCastingExtrusio