锻造方式对7075铝合金锻件动态再结晶的影响

338Vol.33,No.820048RAREMETALMATERIALSANDENGINEERINGAugust20042003-01-072003-04-07(G1999064908-04)[e-mail]70751,222222(1.110004)(2.710016)OMTEM70757075Z7075TG146.2+1A1002-185X(2004)08-0827-04[1,2][2~7]ZZenner-HollomonZ)/exp(RTQe&e&QTRZ70757075Zn:5.67Mg:2.24Cu:1.47Cr:0.14Fe:0.22Al()102s-1440=lnH/h(Hh)17075440Table1Processingparametersoffreeforgefor7075Aluminumalloyat440SpecimensnumberMethodsofforgeTotalstrainAveragestrainofper-passPass1Singledirection1.451.4512Singledirection1.61.613Singledirection0.80.424Singledirection1.150.57525Singledirection1.250.62526Singledirection0.90.1857Doubledirections2.21.128Threedirections4.20.3512OlympasPMG395%5%JEM200CX82833160kV170751.451a1.61b270752a1.252b52c1Fig.1OMstructureofforgedpieceforsinglepassatinitialtemperatureof440:(a)å=1.45and(b)å=1.62Fig.2OMstructureofforgedpieceforsinglepassandmulti-passatinitialtemperatureof440:(a)doublepasses,å=0.8,(b)doublepasses,å=1.25,and(c)fivepasses,å=0.932.24ìm44.2TEM1ìm~2ìm3[9]()Z707570751)2)1.550ìma50ìmb50ìmab50ìmc50ìm870758290.93Fig.3OMstructureofforgedpiecefordoubledirectionanddoublepassesatinitialtemperatureof440,å=2.24TEM440,å=4.2Fig.4TEMstructureofforgedpieceforthreedirectionandmulti-passesatinitialtemperatureof440ZZ70751.610ìm~15ìm2.25ìm4.21ìm~2ìm70753[2]7075270751)2)Al12Mg2Cr557075TEMFig.5Morphologyofsecondaryphaseparticlesof7075aluminumalloyunderTEM1)707520ìm0.5ìm2ìm830332)70753)4)ZReferences[1]CuiZhongqi().MetallurgyandHeat-Treat()[M].Beijing:ChinaMachinePress,1991:10[2]PanJinsheng(),TongJianmin(),TianMinbo().TheFoundationofMaterialsScience()[M].Beijing:TsinghuaUniversityPress,1998[3]ZhangTingjie(),ZhangXiaoming(),TianFeng()etal.RareMetalMaterialsandEngineering()[J],2001,30(5):335[4]ZhangTingjie(),ZhangXiaoming(),TianFeng()etal.RareMetalMaterialsandEngineering()[J],2002,31(4):257[5]ZhangYonghong(),YinZhimin(),ZhangJie()etal.RareMetalMaterialsandEngineering()[J],2002,31(3):167[6]LiHuizhong(),ZhangYonghong()etal.RareMetalMaterialsandEngineering()[J],1999,28(2):110[7]ShenJian()etal.RareMetalMaterialsandEngineering()[J],1997,26(5):26[8]TakuSakai.JournalofMaterialsProcessingTechnology[J],1995,53:349~361[9]GourdetS,MontheilletF.MaterialsScienceEngineering[J],2000,A283:274~288[10]TakuSakai,XuyueYang,HiromiMiura.MaterialsScienceandEngineering[J],1997,234~236:857~860[11]GholiniaF,HumphreysJ,PrangnellPB.MaterialsScienceandTechnology[J],2000,16:1251~1255TheInfluenceofForgeModeonDynamicRecrystallizationfor7075AluminumAlloyduringForgingZhouJian1,2,ZhangTingjie2,ZhangXiaoming2,MaGuanglai2,TianFeng2,ZhouLian2(1.NortheastUniversity,Shenyang110004,China)(2.NorthwestInstituteforNonferrousMetalResearch,Xi’an710016,China)Abstract:The7075aluminumalloyisforgedatdifferentstrainindifferentways.OM(opticalmicroscope)andTEM(transmissionelectricmicroscope)wereemployedtoobservethemicrostructureof7075aluminumalloyafterhotdeformation.Experimentresultsindicatedthat7075aluminumcanoccurdynamicrecrystallizationunderhotforgingandfinegraincanbeobtainedatthesametime,whoserecrystallizationmechanismandnucleationmechanismarediscontinuousdynamicrecrystallizationandsubgrainrotationandpolymerizationrespectively.Itscriticalstrainvalueisrelatedtodeformationpass,themorepassesare,thesmallercriticalstrainvaluewillbecome.Recrystallizedgrainsizedecreaseswithincreaseofstrain,anddispersedsecond-phaseparticlesplayaveryimportantroleduringdynamicrecrystallization.Keywords:7075aluminumalloy;criticalstrain;dynamicrecrystallization;second-phaseparticlesBiography:ZhouJian,Male,Master,NorthwestInstituteforNonferrousMetalResearch,Xi’an710016,P.R.China,E-mail:[e-mail]