機(jī)械畢業(yè)設(shè)計(jì)英文外文翻譯90大尺寸塑料模具鋼AISIP20鋼的淬火過程設(shè)計(jì)

J.Mater.Sri.Tcvhno].;Xol.22Nel,20D6 1J9DesignofQuenchingProcessforLarge-sizedAISIP20SteelBlockUsedasPlasticDieDtmgliSONG'.JianfnngCU；.iianshengR4Aanr/XinVA。KeyLaboratoryoftheMinistryofEducationofHighTemperaturoMaterialsandTtesling,ShaugliaiJiaoTongUniversity-Shanghai200030?China[ManuscriptreceivedOctober21,2004.inrevisedformMarch4,2005]Forlarge-sizedAISIP20steelblockusedasplasticdiewithathicknessofmorethan200mmhappropriatequenchingprocessesarethekeytoobtainmuchthickhardenedlayer.Imthispaper,differentquenchingprocessesofAISIP20steelblocksuchasoilquenching,directwaterquenching,waterquenchingwithprecoolingandwaterquenchingwithpre-coolingandself-temperingwereniLimencallyinvestigatedbycomputersimulationbasedonthedetaileddiscussiononthemathematicalmodelsofquenchingprocessesincludingpartialdifferentialequationsofheattransfer,thermalphysicalproperties.,latentheat,heattransfercoefficientandcalculationofphasetransformation,Theresultsshowthatthewaterquenching牝ithpre-coolirigandself-temperingprocesscannotonlyeffectivelyavoidquenchim^cracks,butalsoobLdWid-.?eperhardendepththanoilquenching.KEYWORDS:Computer空心ia;Juei.chingprmg"；A￡S1P2DsteelyPlasticdieIntroductionAISIP20steel,couiinoiilyusedasplasticdiest-eeLisusuallysuppliedinpre-hardenedstatewiththehardnessofabout30~36HRCafterquenchingandtempering^1^）.TheP20steelblockshouldhaveuniformhardnessinthesamesectionwiththebiggestliardncssdifference3HRCMidtheamountofproeutectoidferriteshouldbeaslittleaspossible.AsAISIP20steelhasmiddlehardenabilitywiththecomposition?f C,0蟲。％?0.80%Si,0.60%-L,00%Mm1.40%?20%Crt0.30%?0.553%Mo,<0.03%Sand<0-03%P-.themaximumthicknessoftheblockshould,not-bemorethan150mmwhilequenchedinoil.Forlargesteelblockwithathicknessofmorethan150niin,appropriatequenchingprocessesarethekeytoobtainmuchthickhardenedlayer.However,quenchingis題complexprocessinvolvingthermal..metaJlurgicalandchanicalphenomena.Itisdifficult,eveninipossi-ble1odf*scribeal）theseptiysicalphenomeiiauor-rectlyandefficientlywithanalyticmethods.Therefore,theestablishmentofquenchingprocessisonlybaserIonexperienceandlarksscientificbasismthepast.Inrecentyears,greatprogresseshavebeenachievedincomputesitnulatio-n.Thecouplingteinperature-phasotjaiisfoiination-stress^^5^threedimensional（3D）non-linearfiniteclementmethod（FEM）aimlysisl&wLthecalculationofphasetrans-forniatiojikineticsf9^11],andthedealingwithabruptdialledboundaryconditions^12J31havebeencarriedouIandtheiraciiksvernentshaveprovidedasoiumdbasisfortheapplicationofcomputesimulationinguidingmanufacturing.Inthispaper,differentquenchingtPhD.?towhomcorrespondenceshouldt>eaddresseci,Ij-ttiall：winler=songl&'sjtiii.cdllcn.

processesofAISIP20steelblockwereinvestigatedbycomputersimulation,andthequenchingprocessofwaterquenchingwithpre-coolingandself-temperingwasproposed.MathematlealModelsofQuenchingProcessesPartialdifferentialequatioiiof血液tLr的sfiuTheheatconductionofthelarg^-sizedblockdur=ingquenchingcanbecalculatedbythefollowing3Dgoverningpartialdifferentialequation:備攜）+畚（湍）+親（璧）+卜附晉⑴itsboimdnryt：onf]i[.ioriandUu?initialconditioncanIjpexpressedas：—煤=仰-孔） （2）=處（壬9疽} （3）whereA,p5qaretheIhermalconductivity,.th聆nietssdensityTthespecificheatsuidinternalhealsourcedensity,respectively.霸isthetenipcraturegradientperpendicularlytothesurfac.e:isthesur?fareteinperatore；THisthetemperatureofthequenchant,andhistheheat,transfercoefficient,whichisinputafiinctionofsurface!temperatureofsteelblock.InthetransicBttemperaturefieldaiia!ysistthe3DFEMformatoftheaboveheattransferequationistheforthformula,,whenitstimedomainisdiscretedbythebackwarddifferencescheme.（圓+￡?）V= 金I{F\（4）140J.Mater.Sci.Tfechncii,Vol.22NqJ2006Fi昏1Thermophysica)propertiesofdifferentmitrostnictureinAISJP20stecliNh(a)thermalconductivity,(b.)specificheaj(c)density(M=marUn3ite,B=bainiteJP=pearlite3F^ferrite,A=austenit時(shí)Fig.2DiiigramofiheprobeFig.2Diiigramofiheprobeandpositionsofthcrnio-cou-pksTable1Enthalpydifferencebetweenaustensiteandotherconstituents^^XficrostruutureFerritePerliteBainite#artensite△W/31護(hù)J/m3)沁_(dá)jij6#vlieredJ孔istheenthalpydifferencebetweenausteniteperunitandthefcthphasepcrunitwhisnaustenitetransforms,showninTable1“切andd￡k浦thevolumefractionoftheAthduringdf.HeattransfercoefficientWhftncoolinginair,thecombinedheattransfercoefficientincludesradiationtraiisfercoefficient[知)andconvectivetransfercoefficient(hr).thatishair=hr+知 (7)Theradiationtransfercoefficientisrepresentedaswhereeistheradiationemissivityofthesurface,setas0.6inthispaper,gistheStefatbBoltzmannconstantwiththevalue!of5768xl0&8W/(m2K4)+Theempiricalformulaofconvectivetransfercoefficient知inair-coolingisapproximatedwhere[K]and\C]aretheconductivitymatrixandtheheatca[)acitymatrix：respectively.{F}istheheatsupplyvector.Themal propertiesTheabove-mentionedthermalphysicalpropertiesareinfunctionofphaseconstitutionandtemperature,明showninFig。"%andcanberepresentedas:when?珞representsA,orcp?and&治thevohumefractionofkthphases;krepresentsA(austenite)M(niartensite),B(bainite)>P(pearlite)andF(pre-eutectoidferrite)srespectively-LatentheatThedensityofiiiterualheatsourceqisgeneratedbyphasetransformationandcanbecalculatedbyat加.-2.2</r.-7； (9)TheheattransfercortlkieinLofoilandagitEil-mgwHterarcdetenuiiicidhy"InverseHeal^VaiisferMethod"(IIITRl)'""Firstly,thectjolin^cu^esatf?acquiredbyadat.nacquisitionsystemwithUi^rnio-couplesin^tailedindifferuntpositionsofaflatprobewiththesizeof120mmX120mmx^Onirn,asshowninFig+2+Then,thesecoolingcurvesareinputintoafinitedifferenceprogrambasedonIH'TMtocalcii-latetheheattransfercoefficient.Thecalculatedheattran5:rcoefficientsofoi)andtheagitatingwaterinatanker<jf4,5nix7.5mx4mareshowninFig.3,Calculationofp瞄etrAn^miationPhaset.Laflsfcnnationsduringquenchingarcusuallyclassifiedintodiffusiont.ransfomiH.r.ionBanddif!usioule8Ht.rangformations[martensitictransfonnatiem)"一

廠廠w』E5J二與所￡菖與￥Fig.3Heattransfercooflickut.ofoilandagitationwater:Fig.3Heattransfercooflickut.ofoilandagitationwater:(a)oil,(b)agitatiohw&ter(MEJKH10^0^畫沼姓二碧hJ.Mater.Sci-TechnoL,VoL22NoJ,200(i141Fbrdiffusiontiaii^tbrinatiorijtin?continuomcoolingcurvescanbediscretcxlintoisotlieniicilstagesofveiyshorttinieinterval】*』可.TheScheiladditivitynj]e"SIsadoptedtocietenninetheincubationperiod,wliichstandsforthetimeatwhiclithetransforniatiotibegins.AteverytiniRiiicremeiilafl.crthebeginningofthepha^etr^isformation,John-Mehl-Avramit21formulaisusedtodeterminetheJ.Mater.Sci-TechnoL,VoL22NoJ,200(i141Theschciladditivityrule：(10)John-MehI-Avramie<jii.ation:TOC\o"1-5"\h\z/mI-改p—祀。 (11)Thevirtoiiltime:*fln(l- ,一、杵=一'/ (12)iS」Thevirtualvolumefraction:療=1一四「(7"；+8廣) (13)Therealvoluiriefraction：/=/n/ri-L+/t-l)/niiax (14)wherer^r)istheincubationperiodatacertaintern-peraiureT;istheshortisothermaltimestageatthecertaintemperattireT;bandnareconstantsthatcanbecalcuhtecibytwodifferentcurveswithnewph於evolumefractions1%and99%onthetime-tcnipcrature"transformation(TTT)diagram,respec-tively^andaretlievolumefractionofnewphase1atthelimeofi-1andi,j神?iisthevohmiefractionofausteniteat.th?timeofandisthevolumefractionoftheretainedausteniteatthebe-giimingofanewphasetransformation.FbrtheniarbensitictreHisfonnation,thequantityofinarteiisiteismere^lyafonctionofleniperature.ThevolumefractionCtinbecalculatedbytheestablishedKoistiiwn-MarburgGr1hw「思]：/=1-exp(a(Mft-T)) (15)whereisthemartetisit^transformationstartten>peratureamiaisaconstaiit.withavalueof0.()23fortheAISIP20steel.ResultsandDiscussionCoinnicTcialFEsoftwareMSC.Marcanduser-definedsubroutinesareenyvioyedtoanalyzethequenchingproc浮eofAlSiP20觥況】block.Thelarge-si^edP2Ctloekh%dimensionof1H.'OHim1000mnixASGmm.Owingtothesym-nietrycrlyoneeighthofthegeometryisripcessarilytobeCDiigiderecLThesizeofmeshandtheappropriatebiasf眈t心『areobtainedbytrialanderror-The□ptimalFEinHshsizel)ywhichsatisfactoryresultscanbeobtainedisshowninFig,4.Forthecalculation□fphasetransformationdiiriiigquenehi皿g,theTTTdiagramofAISIP20steelistestedusingdilatwinetiT,asshowninFig5OilquenchingOilisoftenusedasthequenchautofAISIP20s^teelblocktoavoidcrackingduringquenching.TheheattraiisfercoefiicientofoilisshowninFig,3(a).Afteraustenitizedat860°thelarge-sistedblockwastheaiquewhedintotheoiLThecalculatedinkcrostmcturedistributionalongthecentralaxisafteroilquenchingis，showninFig.G.AsshowninFig.6]nomartensitecanbeibinid,andbainitelayeristhin.Pearlitestartstoappearatthepointabout10mmfromtheblocksurface-Themainphaseformthepointabout50itmifromthesu『fae整tothecenterispearlite,whilethevolumetractionofferritereachesthepeakvalue12.5%.The其fbr軋oilquenchingisnotsuitableforthelarge-sixedP20steelblock.Direct同Eerq眼皿油禰Breauxthe?hardenlayeristoothin,agitatingwateristakenasthequenchantinsteadofoiLAfteraustenitizedat860°C-,theblockwasthenquenchedint-owatercoolingtoroomtemperature.Thecal^culatedmicrostructuredistributionMungthecentralajcisofthekuge-sizeddieblockafterwaterquenchingisshownhiFig.%BecauseofthehigJiercoolingabilityofagitatingwaterseiiiifromFig.3(b)Tpearliteappearsbelow30minfromthesurface,whileferriteappearsfrom100mm.Thevolumefractionofferriteinthecoreiticr-eas^fitonomorethan10%.There比電water3,i.F，二心“".孔??obtainmoresuitablernicTostrnctiires.JrMater.Sri. Vrt)L22NoJ,200^■■■aquenchiugr，苫+UIVli^.LUbLAIlVtUlV'UIUUI1IJUI.-JUIIfU(J好E?”舊 cl-ALrsofHiiRblockafteroilquenchingThoughbetternlicrost.ructUitTdistribtitioncanbeobtainedbydirectwatprquenchhig,theproblemsofquenchingcracksalwaysoccur(luiingpracticalheattreatrnent.Cracksusuallyinitiatearoundthecorneruftlie巍1砰【block.Thercfbrpjsuitablequeuchiiigprocessw麗fitrtherinvestigated.Waterquenchingwithairpr@co況ingAsseenfromFig,&crackingduringdirect,waterquenchingisapparentlyrelatedwiththernartetisctetrcHisforniationaroundtheeonipr.ToovercometheproblemSjanewquenchmgprocessofwaterquenchingwithairpre-coolingwasdesignedandsimulatedinthispaper.Figure9showsthecontourofpearlztedistributionaftf*rairpre-coolingfor1200s.Ascanl>oseenfromFig.9(a),afterprc-cuoliiLgforappropiiatetime,austeiiitearoundthecornertransformsintop^arlit-e,whichwillconsequentiallydecreasethetendencyofCrockinginthesubsequentwaterquenching.Figure9(b),(c)and(d)showsverythinlayerof|>?arlitearoundthe?cjorner,midausteniteh¬decomposedafterpre-coolinginmostregionoftheblock.InthesubsequenLwaterquenchingpr(jce^tthenondecomposedaustenitewillcontinuouslydecompose做incaseofthedirectwaterquenching(seeFig,10).PracticalheattEeatmciitonthelarge-sizedP20stcielprovepre-coolingcaneffectivelyavoidqticnch*ingcrackstbutsomelittlecrackymaystillgenerate,Thesecrackslyingnearthesurfaceartsr:ausedbyiiiarten^itetraiisforriiatiouduringwatprquciidling.Tofurtheroptimizethequenchingprocessofthelarge-sizedAISIF20steelblock,anotherquenchingprocessofwaterquenchingwithaii"pre-cooling<utdselftemperingwasdesignedandsimulatedinthisp*per.Waterquendiijigwithairprt^eoolingThecoolingcurvesofdiffereiitpositionsalongthecenteraxisareshowninFig.lLThe(|uciidlingprocessincludesfourstage*th。pr^raoJingof111Ss*thrfirstwater(pjeiithingof3892s1thefirst,aircoolingof201缶andthesecondwaterquenchingof2380srAscanbefleenfromthesiniulatedrewultBinFig.11,thesurfacetemperatureapproaches100°Cafterthefirstwaterquenchii】giwhichisaJrea^iybd口wMepointysothemartensitebeginstotransform.If

DI&甬白f/omaurf&cfl/mm113J.Mater,Sci,rrcchnol.1Vol.22No/l.20D6uricuipearmcdisrriDuiiQnitreerairpre-cooimgzorizuus：[ajpearlitedistributioninthewholebkx：k.(b),(c)(d)pearlitedistributionsinthesectionswithdifferentdistfineesawavfromthesnrfacsJ--O--U —ISWL』UlL』*113J.Mater,Sci,rrcchnol.1Vol.22No/l.20D6uricuipearmcdisrriDuiiQnitreerairpre-cooimgzorizuus：[ajpearlitedistributioninthewholebkx：k.(b),(c)(d)pearlitedistributionsinthesectionswithdifferentdistfineesawavfromthesnrfacswawrque虹thingandquenchingwithpre-coGlingcontintiedcoolinginwater}theblockwillbein.dangerofgeneratingquenchingcracks.Atthistime,theblockistakenoutofwaterforthefirstair-cooling,andtheheatconductedoutfromthecenterwillincreasethesiirfaxtetemperaturetoabove200CTC.Therefore,thetransformedmartensiteistemperedanditsbrit-tknesfidecteases?whiletheshorttimetempesringwillno*affectthecxxilingrateofthecore.Aftersecondwaterquenchingjthesurfacetemperatureislowerthan1(K)0C\andthecentertemperaturealsodeceasestoapproximately300口C.Sotheblockcanbetakenoutofwaterandstayinairthatthenewlytrans-fortriedinartcnsiteandbainitenearsurfacearesimi-1 Luiiiii^LUivt!^liumtuesuriiicfj[.ochccoreoftheblockduringwaterquenchingwithprecoolingandEelf-teniperinglariyseif^leinperecl.Thismethodiseffectiveinavoidingquenchingcracks,andthemicrostructuredistributiontreatedbythismethodisalmost,thesameasthattreatedbydirertwaterquenching.ConclusionsBasedonthethermalandmicrostnicturalinathe-maticalmodels,thequenchingprocessesoflarge-sized就朗]blockforplasticdieareinvestigatedl.Itpointsoutthatwatercanreplaceoilasquenchant,andwaterquenchingwithairprp-roolingandself1temperingprocesscanbeoneofidealquenchingprocesses.144144J,Mater,Sci,Techno!,,VoL22No.1)200GThe1700mmx1000mmx460nirnAISIP20steelblockisfirstpre-couiedinairafteraustenitizinguntilathinlayerofpearlitetransformedaroundthecornerwherequenchingcracksaremosteasilytogenerate.Inthefollowingwaterquenching,whenthesurfacelayerwastransformedintomartensite,theblockwastakenoutofthewateranddwelledinairTwhichhadthenewlyformedmartensiteselftempered.Thecenterlayeroftheblockcancon-tiniuetotrajisfbrmduringsubsequentwater-coolingafterself-tempering.Thesimulationresultsshowclearlythatpre^coolingandself^temperhigdoesnotreducethehardendepth.Themicrostructurf?distri-butionfiaresimilarinwaterquenchingwithqtwithoutpre-coolingandselStempering,butthelattercaneffectivelypreventquenchingcracks?andcanobtaindeeperhardenlayerthanoi]quenching.Acinow/edgejmentsTheprojectwassupportedbySciencear>dTec^iiol-□gyMiiiistryiifCbiiia(NO.MT1:1Tmauthorswishtosincerelyacknowicd^r!;i」iaMs'Uxce&「頃 andotherstudent成REFERENCES[1]YikaanLIUandBingZHANG:HeatIkeaLMetcds,1991,32(11),46.(inChines)[2]XinYAOtJianfeng;GUandMiugjuaiiHU：HeatTreat-'褊￡法「2003.28(7),33.(inChmese)[3]T.InoueandKJauaLa;J.Sco,Mat.ScLJpn.,1973,22,218.[4]S.D^nisau<lPrArclianibault:Proceedingsofthe*3rdIiit.Conf,onQu-enchingandCowtrolofDistortion,199,263.&]B.BudbmayandJ.S.Kirkaldy：J,JfpatTYeat-,R,127,[6JJiaiishengPAN,MingjuanHU,DongTIANandDougHUAN：Heat.TechnoL,1998,(1),L(inChinese)[7]1Inoue,H.InoueandFJkuta：Proceedingsofthe3rdInt,Conf,onQuenchingandControJofDistortion,1999,243.[8jXiao(Leo)CHEN;Adi。Afater.Process..1997,152,44w-44j\[9JZuyacXU:TheFrijacipJeofPhaseTr&nsform^tiuiLf1stcd,,SciencePress,Beijing,1999,(inChinese)(10JI.RetitZ.FriedandI.Felde：Proc,ofthe3rdInt.Conf,onQucuciiingantiCantroJofDisErtkni,1999,157，T.T.Pham,E.B.HawboltandJ.K+Briinacombe：Met-allMater.A,1995, 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ActaM砒aiJ”1959.(7),50.翻譯譯文?Ft?大尺寸塑料模具鋼AISI.P20鋼的淬火過程設(shè)計(jì)大尺寸的AISI,P20鋼，用于厚度不小于200mm的塑料模具鋼，為獲得一定的淬硬層，適當(dāng)?shù)臒崽幚磉^程是十分關(guān)鍵的。本文就AISI.P20鋼的不同熱處理過程如油淬，直接水淬，水淬前預(yù)冷和自我回火，做了計(jì)算機(jī)模擬的數(shù)字調(diào)研，對(duì)數(shù)學(xué)模型熱處理過程細(xì)節(jié)做了討論，包括局部熱傳遞的不同反應(yīng)式，熱物理性質(zhì)，潛熱，熱傳遞系數(shù)和相變計(jì)算，結(jié)果顯示；預(yù)冷水淬和自我回火，不僅能有效地防止淬裂，而且比油淬獲得更深的淬硬層關(guān)鍵詞：計(jì)算機(jī)模擬，熱處理過程，AISI.P20鋼，塑料模具前言AISI.P20鋼，塑料模具鋼，通常淬硬前硬度值大約30?36HRC。P20鋼應(yīng)該有均勻的硬度，在同一截面上，硬度值最大不超過3HRC，這就要求共析鐵素體盡可能少。AISI.P20 鋼 ：0.28%?0.40%C,0.20%?0.80%Si,0.60%?1.00%Mn,1.40?2.0%Cr,0.30%?0.553%Mo,<0.03%S,<0.03%P。油淬時(shí)鋼的最大厚度不應(yīng)超過150mm。厚度超過150mm的大尺寸的鋼，為獲得一定的淬硬層，適當(dāng)?shù)臒崽幚磉^程是非常關(guān)鍵的。然而熱處理過程是包括熱傳遞現(xiàn)象，冶金性，力學(xué)現(xiàn)象等復(fù)雜的過程。它很難或者說不可能用分析的方法來正確而有效地描述所有的物理現(xiàn)象。所以，在過去，熱處理過程的建立只是根據(jù)經(jīng)驗(yàn)，而缺乏科學(xué)依據(jù)。近年來，計(jì)算機(jī)模擬使其有了巨大的進(jìn)步。進(jìn)行溫度與相度應(yīng)力的耦合。3D非線性有限元素分析，相變動(dòng)力的計(jì)算。對(duì)急劇轉(zhuǎn)變邊界條件的處理等。這些計(jì)算結(jié)果為引導(dǎo)制造業(yè)的計(jì)算機(jī)模擬，提供了一些基本法則。本文中，分析由計(jì)算機(jī)模擬的AISI.P20鋼的不同熱處理過程，提出預(yù)冷水淬和自我回火熱處理過程的數(shù)學(xué)模型2.1熱傳遞過程中，局部不同的反應(yīng)：大尺寸鋼在熱處理過程中的導(dǎo)熱量，可以通過3D模型局部不同反應(yīng)方程計(jì)算出來

ddT.ddT.ddT. dT—(人—)+—(人—)+—(人—)+q—pc—dXdxdydydzdz pdt邊界條件和初始條件為:(2)(3)dT(2)(3)T—0—T(x,y,z)人是導(dǎo)熱性，Cp是比熱容，q是內(nèi)熱源矛是垂直于表面的溫度梯度，J是表面溫度，[是淬火介質(zhì)溫度，n是傳熱系數(shù)。邊界條件與初始條件作為鋼的表面溫度的函數(shù)輸入。在分析瞬時(shí)溫度時(shí)，3D有限元分析法解傳熱方程用前一個(gè)反應(yīng)式，當(dāng)時(shí)間范圍是離散的，應(yīng)用后向差分格式。Ik]+—[c]\{t}=—[c]{t}+{兩 （4）" At ）tAt t-At這里的[K]代表模具導(dǎo)熱率，[C]代表模具熱容率，{^}是供熱介質(zhì)。熱物理性質(zhì):fVfV T^rnci.i吟 Rmp.j"C圖1在AISIP20鋼上不同微觀組織的熱物理性質(zhì)：（a）導(dǎo)熱率（b）比熱（c）密度（M=馬氏體，8=貝氏體，？=珠光體，？=鐵素體，人=奧氏體）上述圖1顯示：熱物理性質(zhì)是相成分和溫度的函數(shù)，可表示為W（r,q）=ZWk（T） （5）這里的W代表人,P,或%,&k是第k相的體積分?jǐn)?shù)，k分別表示為A（奧氏體），M（馬氏體），B（貝氏體），P（珠光體），F(xiàn)（共析鐵素體）潛熱由相變產(chǎn)生的內(nèi)熱源的密度由（6）計(jì)算d& 、q=hHk~dk （6）這里的叫是當(dāng)奧氏體轉(zhuǎn)變的時(shí)候，每單位奧氏體與每單位第k相的焓差。如表-1所示。d&k是第k相在dt中的體積分?jǐn)?shù)。TaLIt；1EcithidipiyclLFfereDeebetwesn如誦&色白帝日巳 ntherMitrCfftructurc Ferrite Pearlite Uainitc WartenstFJ/ma} 5-9 &.L' 5-i 6.3熱傳遞系數(shù)當(dāng)在空氣中冷卻時(shí)，綜合的熱傳遞系數(shù)包括：輻射傳遞系數(shù)（h）和對(duì)流轉(zhuǎn)移系r數(shù)（h），即Ch.=h+h （7）輻射傳遞系數(shù)（h），表示為：rh=2T+T）（T+T） （8）這里e是表面熱輻射系數(shù)，本文中取為0.6，b是Stefan-Boitzmann常數(shù)，b=5.768x10-8w/(m2k4)在空氣中冷卻的對(duì)流轉(zhuǎn)移系數(shù)的經(jīng)驗(yàn)公式可近似地表述為（9）h=2.2^T~（9）油和攪動(dòng)的水的熱傳遞曲線是反向熱傳遞方法取得（IHTM）。首先，從數(shù)據(jù)采集系統(tǒng)取得冷卻曲線；這個(gè)數(shù)據(jù)采集系統(tǒng)在不同位置有平探頭，尺寸120mmx120mmx20mm，如圖2所示。然后，這些冷卻曲線輸入基于ZHTM的有限差系統(tǒng)。從而計(jì)算出熱傳遞系數(shù)。圖3所示是計(jì)算之中和攪動(dòng)的水的熱傳遞系數(shù)。用的槽車，尺寸為4.5mx7.5mx4m。

(-.XJ苫世晦邑」里忍世二出工Fig.3(-.XJ苫世晦邑」里忍世二出工Fig.3I[&at11aiisfei□吧flkisniofoiland water：3)oil:(b)agitatkniwater萋一~M魚建加匚四二里2.5相變計(jì)算在熱處理中的相變通常分為擴(kuò)散型相變和元擴(kuò)散型相變（馬氏體轉(zhuǎn)變）對(duì)擴(kuò)散型相變，持續(xù)的冷卻曲線可能被打斷，在極短的時(shí)間間隔的恒溫區(qū)。孕育期采用的是Scheil可加性法則來確定，也就是標(biāo)志相轉(zhuǎn)變開始時(shí)間John-Mchl-Avraml公式用來確定潛伏時(shí)間和評(píng)定微觀組織的體積分?jǐn)?shù)Scheil可加性法則:（10）△t

i—（10）T(T)iJohn-Mehl_Avarami反應(yīng)式:

(11)f=1