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AirbendingofAZ31magnesiumalloyinwarmandhotformingconditionsC.Bruni,A.Forcellese,F.Gabrielli,M.SimonciniDepartmentofMechanics,PolytechnicUniversityofMarche,ViaBrecceBianche,Ancona,ItalyCONCLUSIONS1.Inalltheprocessconditions,theformingloadincreasesinearlybendingstageandthendecreasesduringthefinalstage;2.Foragiventemperature,strokeandpunchspeed,springbackdecreaseswithdecreasingpunchradius;3.Springbackdecreaseswithincreasingformingtemperature,irrespectiveofthepunchradiusvalue,eventhoughsucheffectisreducedwithdecreasingpunchradiusandbecomesalmostnegligibleforthesmallestoneinvestigated;DISCUSSION1.Theinfluenceofthepunchradiusonspringback;foragiventemperatureandpunchspeed,anincreaseinthespringbackratiowithdecreasingRappears.2.ThepunchspeedcanbeseenthattheKvalueisalmostinsensitivetov,evenifatrendcharacterisedbyaslightdecreaseinspringbackwithincreasingpunchspeed.3.Foragiventemperatureandpunchradius,thevolumefractionrecrystallisedincreaseswithincreasingpunchspeed.RESULTS(CONT.)Punchspeedeffectonthemicrostructureofthebentspecimens,R=4mmandT=300◦C:(a)v=0.45mm/sand(b)v=4.5mm/s.RESULTSThespringbackratioincreaseswithincreasingtemperatureandpunchradius.INTRODUCTIONOverviewandimportance.TheeffectoftheprocessparametersonspringbackofAZ31magnesiumalloywasinvestigatedbyperformingairbendingtestsunderwarmandhotformingconditions.Magnesiumalloyshavebeenemergingaspotentiallycandidatesforseveralapplications,inparticularforlightweightstructuralandfunctionalpartsintheaerospace,automotiveandelectronicindustries.Objective.Todate,themechanicalpropertiesofmagnesiumalloyswereinvestigatedbymanyresearchers[1–15];however,nosystematicstudyontheeffectoftheprocessparametersonspringback,underwarmandhotformingconditions,canbefound.Reference1.F.-K.Chen,T.-B.Huang,C.-K.Chang,DeepdrawingofsquarecupswithmagnesiumalloyAZ31sheets,Int.J.Mach.ToolsManuf.43(2003)1553–1559.METHODSMaterialAZ31magnesiumalloywassuppliedinformof3mmthicksheets,50mminlengthand27mminwidth.Thechemicalcomposition(inwt%)oftheMgalloyisthefollowing:3%Al,1%Zn,0.2%MnandbalanceMg.ExperimentalproceduresV-punchandU-diebendingexperimentswerecarriedoutatdifferenttemperaturesrangingfrom100to400◦C,withdifferentvaluesofpunchspeed(v=0.45and4.5mm/s).ThreedifferentV-punches,withaconstantangleof60◦andnoseradii(R)of2,4and6mm,wereusedinthebendingtrials.PunchspeedeffectonthespringbackratioInfluenceoftemperatureontheload–punchstrokecurves(v=0.45mm/sandR=6mm).