铸造A356铝合金的微观组织及其拉伸性能研究

A356,,,(,710049):T6A356,,A3562T62m,100nm,Mg2Si,T6A356Al8Si6Mg3Fe,A356(DCS)(SDAS)Si55m63m20m10m;A35650m75m30m13mA3562T6240MPa25418MPa1116%:A356;;;:TG14612;TG11311;TG11312:A:025426051(2007)0320013206MicrostructureandTensilePropertiesofCastA356AluminumAlloyRANGuang,ZHOUJing2en,WANGYong2fang,XISheng2qi(StateKeyLaboratoryforMechanicalBehaviorofMaterials,SchoolofMaterialsScienceandEngineering,XianJiaotongUniversity,XianShaanxi710049,China)Abstract:ThecastA356aluminumalloywaspreparedusingthelostfoamprocess,andthenheattreatedbyT6technolo2gy.Themicrostructure,microstructuralparametervalue,tensilepropertiesandtensilefracturesurfaceofthealloywereobservedandanalyzed.Theresultsshowntheneedle2shapedMg2Siparticleswithlengthofabout2mandwidthof100nmorseveralnanometers,andelliptical2shapedAl8Si6Mg3FeintermetallicparticleswereobservedinthecastA3562T6a2luminumalloy.Quantitativemetallographicexaminationresultsshowntheaveragevalueofdendritecellsize(DCS),sec2ondarydendritearmspacing(SDAS),lengthandwidthoftheeutecticsiliconparticlesoftheas2castA356aluminumal2loywere55m,63m,20mand10m,respectively,corresponding,50m,75m,30mand13mforthecastA3562T6aluminumalloy,respectively.ThetensilefracturemechanismofcastA3562T6aluminumalloyrevealedatran2granularmodel(alongthecellfracture)withquasi2cleavagefeature.Theyieldstrength(012),ultimatetensilestrength(b)andelongation()ofA3562T6alloywere240MPa,25418MPaand1116%,respectively.Keywords:castA356aluminumalloy;quantitativemetallographicexamination;tensileproperties;microstructure:(1978),,,,;:[e-mail]:2006207230,,,,[124],,,,[426],1%50%,20%[728]Al2Si72Mg(A356)[9]SrA356[10218],A356,SrA356,,,A3561A356,700;,68030minA3561A356T6(5385h,70+1h+1604h)3120073231A356(,%)Table1ChemicalcompositionofthecastA356aluminumalloy(wt%)SiMgFeTiSrAl7.200.390.090.135010-60.05BalanceA356A3562T6,,015mMeF3,SISC2IASV610,:(DendriteCellSize,DCS)(SecondaryDendriteArmSpacing,SDAS)DCS:DCS=L/n(1),L,n(1)SDAS,L,nA356A3562T61mm,,60m,,JEM2200CXA3562T6GB/T2282002A3562T6,01008s-1S22700,,A3562T6221112A356A3562T6Al2Si,A356,Al,Al2Si,Mg2SiSiA356:2AlSiMg2Si,:[19]1a2a2Al,FeFe,,1c2b[19]A356,(Al5FeSi),(Al9FeMg3Si5)A356Si,2Al,1b2b538Al2Si2Mg2Al1b2b,Si,,(12)(12)(1b)Mg2Si,Mg2Si,,;2Al,,[20]A356T6(5381h),Mg2SiMg2Si(4),,1A356(a)(b)(c)Fig.1Theopticalmicrographsshowingmicrostructureofas2castA356aluminumalloy(a)lowpowermicrographs(b)eutecticsiliconandshrinkagecavity(c)iron2bearingcompoundparticles4120073232A3562T6(a)(b)Fig.2TheopticalmicrographsmicrostructureoftheA3562T6aluminumalloy(a)lowpowermicrographs(b)eutecticsilicon,ironbearingcompoundparticlesanddefectsA356(DCS)(SDAS)Si,,2,3,,,60%55m50m,63m75mSi20m30m,10m13m,1b2b2A356/A356-T6Table2ThemicrostructureparametersofcastA356/A3562T6aluminumalloy95%C.l.A356A3562T6/m204.5306/m102.7132.42.12.6(DCS)/m555.1504(SDAS)/m636757.53A356(a)(b)(c)(d)Fig.3Thestatisticanalysisresultsofmicrostructureparametersofas2castA356alloyandA3562T6aluminumalloy(a)dendritecellsize(b)secondarydendritearmspacing(c)lengthofSiparticle(d)widthofSiparticle4A3562T6,,2m,100nm,4a,5120073234aA4b,Mg2Si4c,4cB4d,Al8Si6Mg3Fe212A3562T6A3562T63,35A3562T65,5(5a),5b,5c;,5d4A356-T6(ac)(b)aA(d)cBFig.4TEMimagesandcorrespondingselectedareaelectrondiffraction(SED)patternofcastA3562T6aluminumalloy(a,c)brightfield(b)SEDpatternofparticleA(d)SEDpatternofparticleB5A3562T6(a)(b)(c)(d)Fig.5TensilefractographsimagesofthecastA3562T6aluminumalloy(a)lowpowerfracturemorphology(b)microscopicfracturemorphology(c)inclusion(d)pore6120073233A356Table3TensilepropertiesofthecastA356aluminumalloypreparedbydifferentmethod0.2/MPab/MPa(%)A3562T6240254.81.16A3562T6[21]1862625A3562T6[21]2072786.03,A3562T6113;,=1116%,A3562T623%[21],,,1106,,A3562T61141,A3562T61134,,(),,,[6]Al2Si2Mg,,[22]McLellan,A356A356,,,DAS,,,DAS,,,DAS,Si,,(),DAS,,[22]A356DAS30m,311,A3562T6,20140m,50m,130m,3T6A356,;A3562T6,,:(1)A356Si,2Al,,(2)A3562T62m,100nm,Mg2Si,T6A356Al8Si6Mg3Fe(3)A356Si55m63m20m10m;A3562T650m75m30m13m(4)A3562T6,,240MPa25418MPa1116%:[1]ZhaoHong.Applicationofaluminumfortheautomotivein2dustry[J].AutomotiveTechnologyandMaterials,1997(1):19224.[2]JamborA,BeyerM.Newcars2newmaterials[J].MaterialsandDesign,1997,18(4/6):2032209.[3]MillerWS,etal.Recentdevelopmentinaluminumalloysfortheautomotiveindustry[J].MatSciEngA,2000,208:37249.[4]MayerH,etal.Influenceofporosityonthefatiguelimitofdiecastmagnesiumandaluminumalloys[J].IntJFatigue,2003,25:2452256.[5]WangQG,ApelianD,LadosDA.FatiguebehaviorofA3562T6aluminumcastalloys.PartIEffectofcastingdefects[J].JournalofLightMetals,2001(1):73284.[6]AvalleM,etal.Castingdefectsandfatiguestrengthofadiecastaluminumalloy:acomparisonbetweenstandardspeci2mensandproductioncomponents[J].IntJFatigue,2002,24:129[7]CatonMJ.Predictingfatiguepropertiesofcastaluminumbycharacteringsmall2crackpropagationbehavior[D].Universi2tyofMichigan.AmArbor,MI,2001.[8]Buffie‘reJY,SavellibS,JouneauPH.ExperimentalstudyofporosityanditsrelationtofatiguemechanismsofmodelAl2Si72Mg0.3castAlalloys[J].MaterialsScienceandEngi2neeringA,2001,316:1152126.[9]KwaiSChan,PeggyJones,WangQigui.F