ube.Finally,theeffectsoftheinitialextrusionspeedandthelubricantonthemechanicalpropertiesofthetubeareinvestigated..Theprinciplesofqualitydesign—TaguchimethodTheexperimentscanbeplannedinfourways:()trial-and-error;()one-factor-at-a-timeexperiments;()full-factorialexperiments;and()Taguchi’sorthogonalarrays(OA).Orthogonalarrayscaneliminatethebiasproducedbyone-factor-at-a-timeexperiments,andimprovetheextifytheoptimalprocessparameters.TakudaetaladoptedthefiniteelementmethodtoanalyzetheformabilityofAZmagnesiumbasematerialduringdeepdrawing.Finite关于工艺参数对热挤压镁合金影响研究elementanalysiscanbeusedtopredictcrackingposition,whichcanthenbeverifiedexperimentally.Chenetal.appliedanAZmagnesiumalloysheettostudythedeepdrawingofasquarecup.Followingdeepdrawingatroomtemperature,thefinalsheethaddefects,butatover◦C,theformabilityisimproved.Inarelatedstudyofmagnesiumalloy,Mwembelaetal.studiedthemicrostructureofAZmagnesiumalloyduringhotworking.Ahightemperatureof–Cwasfirstlyemployedforrolling,whichwasfollowedbyforging.AsthetemperatureincreasedoverC,thegrainsgrew,andthestrengthofthealloydecreased.Inastudyoftheextrusionofmagnesiumalloy,Gouveiaetal.usedthefinite-elementmethodtosimulateformingbycoldforwardextrusion.ChandrasekaraandShyanJohninvestigatedthreemagnesiumalloys,AZ,AZandZK,aswellastheeffectoftemperatureonformabilityduringforwardextrusion.Theyshowedthatthesemagnesiumalloyscannotbeformedatbetweenroomtemperatureand◦C,andthatthesemagnesiumalloyscanbeextrudedsmoothlyat◦C,butAZandZKmagnesiumalloysexhibitcracking.Whenthetemperaturewasincreasedto◦C,theAZmagnesiumalloycouldbewellformed.Muraletal.empolyedAZBmagnesiumalloybilletsformedbycasting,aswellashomogenizedmaterialstoperformextrusion.Themicrostructureandmechanicalpropertiesofthefinalproductswerethenstudied.UsingtheTaguchimethodforplasticprocessingdoesnotreducetheaccuracyoftheexperimentalresults,butsignificantlyreducesthenumberoftimestheexperimentsmustbeperformed.Itisthereforeregardedasamoreeffectivestudymethod.Inthisstudy,twomagnesiumalloybillets,AZandAZ,areappliedtocarryouthotextrusionintoatubewithathicknessofmm.TheTaguchimethodisinitiallyappliedintheexperimentalplanningandtheprocessparametersofhotextrusionaresettooptimizethemechanicalpropertiesforAZandAZtube.ANOVAisthenemployedtoanalyzetheeffectoftheprocessparameteronthetube.Finally,theeffectsoftheinitialextrusionspeedandthelubricantonthemechanicalpropertiesofthetubeareinvestigated..Theprinciplesofqualitydesign—TaguchimethodTheexperimentscanbeplannedinfourways:()trial-and-error;()one-factor-at-a-timeexperiments;()full-factorialexperiments;and()Taguchi’sorthogonalarrays(OA).Orthogonalarrayscaneliminatethebiasproducedbyone-factor-at-a-timeexperiments,andimprovetheex控制因素有三种水平。内表是一个正交表,表显示了该正交表。..机械性能试验遵照CNS(JISH),用管材压扁实验作为参考。从管材上切下mm试样,将其放在重公吨试验机平板之间压。焊接区放在压力方向,从而形成一个直角。在压扁实验中,压扁速率为.minmm,当平板位于H=.D时,管壁未发现任何裂纹或破裂。按照说明CNS和CNS进行拉伸实验,拉伸速率为.minmm。.结果和讨论本研究中用到镁合金为AZ和AZ,对其进行热挤压成形为壁厚为mm管材。基于正交表最终实验必须进行拉伸实验和压扁实验,一了解管材机械性能。通过测量质量特性和实施ANOVA来分析由拉伸实验获得抗拉强度,以确定最佳工艺参数组合和各个因素重要性。最后,进行验证实验以验证其精度。..压扁实验分析按照相关说明进行压扁实验。当两平板间距为H=mm时,管壁未产生任何裂纹和破裂。表显示了当H=mm时,有两组坯料AZ和AZ制成管材观察不到破裂,AZ管材可承受载荷在.和.N之间,而AZ管材可承受载荷在.和.N之间。当继续进行压扁实验直至管材破裂,AZ载荷大于等于.N,AZ管材载荷大于等于.N。比较这两组坯料,在H=mm和开始破裂时,AZ管材可承受载荷大于AZ管材。..最大化管材机械强度最佳工艺参数组合关于工艺参数对热挤压镁合金影响研究表显示了管材抗拉强度实验结果,此表中结果显示:AZ管材平均抗拉强度分布于.到.MP之间,而AZ管材平均抗拉强度分布于.到.MP之间。这个比较说明经过热挤压棺材有更高抗拉强度。管材较大抗拉强度对应于更高质量。因此,计算信噪比是越大越好值,用方程,信噪比值列于表.本图表中最大信噪比值产生了最佳工艺参数组合。本研究中考虑工艺参数是坯料加热温度、初始挤压速率、模腔温度和润滑类型。因数效果图,图,揭示了对热挤压AZ管材,最佳工艺参数组合为:坯料加热温度为℃,初始挤压速率为smm,模腔温度为℃和润滑剂为BN。因数效果图,图,揭示了对AZ管材,最佳工艺参数组合为:坯料加热温度为℃,初始挤压速率为smm,模腔温度为℃和石墨润滑。在镁合金质量性能分析中,必须考虑到抗拉强度。用上述最佳工艺参数组合挤压管材产生了具有最高抗拉强度产品。..验证实验用实验进一步验证上述分析得出最佳工艺参数组合,以确认其精度。对AZ管材验证实验中,只改变初始挤压速率(,,smm),其他因数保持不变。在AZ管材验证实验中,只改变润滑剂(BN,石墨,MoS),其他因素保持不变。最后比较挤压管材抗拉强度和微观组织。表列举了由验证实验得到抗拉强度数据。第一组数据关于AZ管材。改变初始挤压速率,当初始挤压速率为smm时,抗拉强度最大,初始挤压速率为smm时和smm时次之。这个结果与图一致。图所示微观结果揭示了坯料晶粒尺寸大于挤压后管材晶粒尺寸。挤压减小了晶粒尺寸,这对强化管材有用。在第二组,AZ管材验证实验,只改变润滑剂。结果表明,当润滑剂为石墨时,抗拉强度最大,当润滑剂为BN和MoS时次之。这个结果与图一致。图所示微观结果表明,坯料AZ晶粒尺寸与管材晶粒尺寸截然不同。挤压减小晶粒尺寸并使之均匀化。..方差分析ANOVA分析用方程()—()。ANOVA用于评估AZ和AZ管材抗拉强度,结果列于表和表.当可信度为.时,对AZ和AZ管材,F值超过.(F=FINV),,.(=.)。因此控制因数A,B,C和D有强烈影响。同样地,对于AZ和AZ管材,控制因数强化效果遵循同样顺序:(A)坯料加热温度;(B)初始挤压速率;(D)润滑剂;C)模腔温度。这个顺序也可以由部分获得。在ANOVA分析中,坯料加热温度具有最强烈效果。因此,控制管材抗拉强度最重要因数是坯料加热温度。在挤压过程中,坯料加热温度改变严重关于工艺参数对热挤压镁合金影响研究影响了管材抗拉强度。.结论.在压扁实验中,管材遵照相关说明。在AZ和AZ管材破裂载荷超过.N和.N。AZ破裂载荷通常超过AZ破裂载荷。.AZ管材抗拉强度分布于.和.MP之间,而AZ管材抗拉强度分布于.和.MP之间。.对热挤压成形AZ管材,最大化其抗拉强度最佳工艺参数组合为:坯料加热温度为℃,初始挤压速率为smm,模腔温度为℃和润滑剂为BN。有热挤压成形AZ管材,最大化其抗拉强度最佳工艺参数组合为:坯料加热温度为℃,初始挤压速率为smm,模腔温度为℃和石墨润滑。.用两组坯料AZ和AZ管材,各种因素对管材抗拉强度强化效果遵循顺序:坯料加热温度,初始挤压速率,润滑剂类型和模腔温度。.无用那种坯料(AZ或AZ),挤压过程在很大程度上减小了晶粒尺寸,增加了管材抗拉强度。tifytheoptimalprocessparameters.TakudaetaladoptedthefiniteelementmethodtoanalyzetheformabilityofAZmagnesiumbasematerialduringdeepdrawing.Finite关于工艺参数对热挤压镁合金影响研究elementanalysiscanbeusedtopredictcrackingposition,whichcanthenbeverifiedexperimentally.Chenetal.appliedanAZmagnesiumalloysheettostudythedeepdrawingofasquarecup.Followingdeepdrawingatroomtemperature,thefinalsheethaddefects,butatover◦C,thefor关于工艺参数对热挤压镁合金影响研究InvestigationoftheinfluenceofprocessparametersonhotextrusionofmagnesiumalloytubesAbstract:Duringthehotextrusionofmagnesiumalloy,thechangeofprocessparameterswillaffectthemechanicalpropertiesofextrudedproducts.Inthisstudy,Taguchimethodandanalysisofvariance(ANOVA)areappliedtoanalyzetheinfluenceofprocessparametersonthehotextrusionofmagnesiumalloytubesunderextrusionratioof..TheexperimentsarearrangedbyorthogonalarraymethodinwhichmagnesiumalloysAZandAZareusedasouterarrays,thefactorsselectedasinnerarraysarethebilletheatingtemperature,theinitialextrusionspeed,thecontainertemperatureandthelubricants.Theextrudedtubeswillbecarriedouttensiletestandflatteningtest,thetestresultsareanalyzedbythequalitymeasurementofTaguchimethodtofindtherelationshipbetweentheprocessparametersandmechanicalpropertiesoftheproducts,andtoacquiretheoptimalcombinationofparameters.Thenbasedontheresultsobtainedfromtheadditivemodel,confirmatoryexperimentsareperformed.Besides,themicrostructuresofextrudedtubesareobservedtoclarifytheinfluenceofprocessparametersonthegrainsize.Finally,withthesameextrusioncondition,thevariationsintensilestrengthandflatteningstrengthduetodifferentcompositionsarediscussed.ElsevierB.V.Allrightsreserved.Keywords:Hotextrusiontube;Magnesiumalloy;Mechanicalproperties;Taguchimethod;Orthogonalarray.IntroductionMagnesiumalloyhaslowspecificgravity,highspecificstrength,goodventilationandshockabsorption.Itisalsoopaquetoelectromagneticwavesandrecycle.Inrecentyears,magnesiumalloyhasbeguntoreplacesteel,aluminumandplasticasproductshavebecomeincreasinglyminiaturized.Magnesiumalloyisandlessdensethanaluminumalloyandsteel,respectively.Therefore,aslightweightproducts,environmentalprotectionandrecyclabilitybecomeincreasinglyimportant,thedemandformagnesiumalloyhasincreasedandbeenextensivelyappliedtotheautomobileindustry,thebicycleindustry,theaerospaceandnationaldefenseindustries,thecivicproductmanufacturingindustryandtheC(computer,communicationandconsumerelectronic)electronicindustry.Atpresent,diecastingisthemainmethodforformingandprocessingmagnesiumalloy.WuandChangusedtheTaguchimethodinthediecastingofmagnesiumalloytoproduceacoverforapersonaldataassistant(PDA),andthustoidentifytheoptimalprocessparameters.TakudaetaladoptedthefiniteelementmethodtoanalyzetheformabilityofAZmagnesiumbasematerialduringdeepdrawing.Finite关于工艺参数对热挤压镁合金影响研究elementanalysiscanbeusedtopredictcrackingposition,whichcanthenbeverifiedexperimentally.Chenetal.appliedanAZmagnesiumalloysheettostudythedeepdrawingofasquarecup.Followingdeepdrawingatroomtemperature,thefinalsheethaddefects,butatover◦C,theformabilityisimproved.Inarelatedstudyofmagnesiumalloy,Mwembelaetal.studiedthemicrostructureofAZmagnesiumalloyduringhotworking.Ahightemperatureof–Cwasfirstlyemployedforrolling,whichwasfollowedbyforging.AsthetemperatureincreasedoverC,thegrainsgrew,andthestrengthofthealloydecreased.Inastudyoftheextrusionofmagnesiumalloy,Gouveiaetal.usedthefinite-elementmethodtosimulateformingbycoldforwardextrusion.ChandrasekaraandShyanJohninvestigatedthreemagnesiumalloys,AZ,AZandZK,aswellastheeffectoftemperatureonformabilityduringforwardextrusion.Theyshowedthatthesemagnesiumalloyscannotbeformedatbetweenroomtemperatureand◦C,andthatthesemagnesiumalloyscanbeextrudedsmoothlyat◦C,butAZandZKmagnesiumalloysexhibitcracking.Whenthetemperaturewasincreasedto◦C,theAZmagnesiumalloycouldbewellformed.Muraletal.empolyedAZBmagnesiumalloybilletsformedbycasting,aswellashomogenizedmaterialstoperformextrusion.Themicrostructureandmechanicalpropertiesofthefinalproductswerethenstudied.UsingtheTaguchimethodforplasticprocessingdoesnotreducetheaccuracyoftheexperimentalresults,butsignificantlyreducesthenumberoftimestheexperimentsmustbeperformed.Itisthereforeregardedasamoreeffectivestudymethod.Inthisstudy,twomagnesiumalloyb 关于工艺参数对热挤压镁合金影响的研究1InvestigationoftheinfluenceofprocessparametersonhotextrusionofmagnesiumalloytubesAbstract:Duringthehotextrusionofmagnesiumalloy,thechangeofprocessparameterswillaffectthemechanicalpropertiesofextrudedproducts.Inthisstudy,Taguchimethodandanalysisofvariance(ANOVA)areappliedtoanalyzetheinfluenceofprocessparametersonthehotextrusionofmag