INMANUFACTURINGCHAINSofmechanicalcompo nents,differentheattreatmentstepscanoccur :forinstancesoftannealing ,stressreliefannealing ,hardeningortemper ing .Hardeningisofspecialinterestfordistortion ,becausetemperaturesarerelativelyhighanddistortionpotentials<1,2 >inthecomponentscanfullytakeeffect.Theindivi dualprocessstepsofmanufacturingchainsinfluencethegeometry,thesegregationdistribution ,themicrostructuredistributionandtheresidual stressdistributionofacomponent.Consequently eachindividualprocessstepinfluencesthedisto rtionofacomponentattheendoftheoverallmanufacturingprocess.Asaconsequence ,thedistor tionpotentialsofthepreviousproductionstepsar ealreadyreleasedduringtheheatingphaseforquenchhardening.Thatmeansthatthecomponentscanexperienceaqui terelevantportionoftheirchangesindimensionandshapealreadyduringtheheatingphasetoaustenitizingtemperature ,additionaltochangeswhichwilloccurwithinthefollowingquenchingprocess .Inliterature ,someofthemainvariablesrelatedtotheheatingphasethataffectdistortionarediscussed<3～ 6 > :Dur ingaustenitizing ,themicrostructuretransformsfromferritepluscarbidetoaustenite ,whichcausesavolumechange .Inhomogeneousheatingordifferentlocalchemica lcompositionofthematerialwillcausedistortio nbecauseoflocalvolumechangebyinhomogeneoustransformation.Residualstresseswhichwerecreatedinthecomponentdur ingmanufacturingarerelievedduringheatingforq uenchhardeningbecauseyieldstressdecreaseswi thincreasingtemperatureandbecomeslessthanth eresidualstresses.Thisleadstoplasticdeformation.Theextentofdistortionisafunctionofthemagnitudeoftheresidualstressandthege ometryofthecomponent.Additionally ,mechanicalforces(gravity)affectdistortionofcomponentsduringheattreat ment.Regardingthisfactor,thestackingarrangem entofthecomponentsinthebatchisanimportantfa ctor.Incontrarytonumerousworkregardingtheinfluenceofcoolingparametersondistortion,theparametersoftheheat ingphasewereonlyexaminedinfewreferences .Milan<3> ex aminedtherelativeeffectsofelevenheattreatmentparame tersondistortionofbearingracesduringheating ,carburiza tion,andquenching .Theresultsrevealthatthemethodofheatingtothe carburizationtemperaturehasagreatereffecton distortionthanthequenchingfactors.ThisisconfirmedbyobservationsofVolkmuth<4> .Theroundnessofbearingringsafterturning ,afternormalizing ,andafterhardeningwascom pared .Afternormalizingandafterhardeningalmostthesameroundnesswasdetected .Theresultswereexplainedbyplas ticdeformationsduringaustenitizing .Intheproject“Distortioncompatibleheatingdur ingheattreatment”oftheCollaborativeResearchCenter5 70“DistortionEngineering” ,themechanismsofdistortionde velopmentduringheatingareanalyzed .Inthefirststep ,dis tortionduringuniformheatingof“homogeneous”componentsisexamined .Inthiscase ,distortionwilloccuronlybytem peraturedifferencesbetweensurfaceandcoreorbymechani calforces (gravity) .Fiveheatingparametersarechangedre gardingtoheatingrate ,austenitizingtemperatureandstack ingofthecomponents.Inadditiontheinfluenceofsoakingtimeandpreheatingisexamined .1 MaterialsandExperimentalProcedure1 1 MaterialsTheexperimentsweredonewithringsofthebearingsteelAISI 5 2 10 0 (EN 10 0Cr6 ) .ThechemicalcompositionofthesteelislistedinTable 1 Table 1 ChemicalcompositionoftheusedAISI 5 2 10 0 (wt % )表 1 试验用AISI 5 2 10 0钢的化学成分 (质量分数 ,% )CSiMnPSCrMoNiAl0 96 0 2 0 0 43 0 0 1 2 0 0 0 71 480 0 52 0 1 0 0 0 0 31 2 ManufacturingofRingsThespecimensusedinthis investigationwereringsofthefollowingdimensions:outer diameter :o=14 5mm ,inner diameter :i=133mm ,height:2 6mm .Thematerialbardiameterwas6 0mm .Theinitialmi crostructureofthematerialwasferritewithspheroidizedcar bides.Theringswereforgedandhotrolledat 10 5 0℃withanoveralldeformationdegreeof φ =0 .6 .Afterwardssoftannealingwasdonetorestoreamic rostructureconsistingofferriteandspheroidizedcarbides.Thefinalmachining(turn ing)oftheringswasdonewiththefollowingcuttingparame ters:(innershell) :cuttingspeed 2 4 0m/min ,cuttingdepth0 7mm ,feed 0 4mm ;(outershell) :cuttingspeed 2 4 0m/min ,cuttingdepth 0
More abstracts about the 加热参数对AISI 52100钢轴承环淬火畸变的影响(英文)