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G1DieLifeandDieFailure模具的寿命及其失效Properselectionofthediematerialandofthedie（[daɪ]n.模具）manufacturingtechniquedetermines,toalargeextent,theusefullifeofformingdies.（直译法）模具材料的恰当选择及其制造工艺，在很大程度上决定了模具的使用寿命。Diesmayhavetobereplacedforanumberofreasons,suchaschangesindimensionsduetowearorplasticdeformation,deterioration（[dɪˌtɪrɪəˈreʃən]n.变坏，退化，损耗）ofthesurfacefinish,breakdownoflubrication（[lubrɪˈkeʃən]n.润滑）,andcrackingorbreakage.（直译法）模具可能会因为一系列原因被替换，比如由于磨损或塑性变形导致的尺寸变化，表面平整度变差，润滑故障，和裂纹即破裂。Inhotimpressiondieforging,theprincipalmodesofdiefailureareerosion,thermal（[ˈθɜ:rml]adj.热的)fatigue（[fəˈtiɡ]n.疲劳）,mechanicalfatigueandpermanent(plastic)deformation.(直译法)在热压印模锻造中，模具失效的主要模式是腐蚀作用、热疲劳、机械疲劳和永久（塑性）变形。Inerosion[ɪ'rəʊʒ(ə)n],alsocommonlycalleddiewear,materialisactuallyremovedfromthediesurfacebypressureandslidingofthedeformingmaterial,wearresistanceofthediematerial,diesurfacetemperature,relativeslidingspeedatthedie/materialinterfaceandthenatureoftheinterfacelayerarethemostsignificantfactorsinfluencingabrasive[ə'breɪsɪv]diewear.（分句法+直译法）腐蚀，通常也称作模具磨损，实际上是材料受压从模具表面剥落的过程。变形材料的滑移，模具材料的抗磨性，模具表面温度，模具和材料接触表面的相对滑动速度以及接触层的性质，都是影响模具磨损的最显著因素。Thermal['θɜːm(ə)l]fatigue[fə'tiːg]occursonthesurfaceofthedieimpressioninhotformingandresultsin“heatchecking”.(直译法）热疲劳发生在热成形中的模具模腔表面,并且最终导致“热裂”。Thermalfatigue([fə‘tig](热)疲劳)resultsfromcyclicyielding([’jildɪŋ]屈服)ofthediesurfaceduetocontactwiththehotdeformingmaterial.（逆序法）由于与热变形材料接触，在周期性屈服的模具表面引起了热疲劳。Thiscontactcausesthesurfacelayerstoexpand,and,becauseoftheverysteep([stip]急剧的)temperaturegradients,thesurfacelayersaresubjecttocompressivestresses.（直译法）这种接触导致表层膨胀，并且，由于温度梯度的急剧变化，表层会受到压应力。Atsufficientlyhightemperatures,thesecompressivestressesmaycausethesurfacelayerstodeform.Whenthediesurfacecools,astressreversal([rɪ‘vɝsl]反向)mayoccurandthesurfacelayerswillthenbeintension.（直译法）温度足够高时，这些压应力可引起表层变形。当模具表面冷却，可发生反向应力，表层此后处于受拉状态。Afterrepeatedcyclinginthismanner,fatigue[fə‘tig疲劳]willcauseformationofacrackpatternthatisrecognizedasheatchecking[热裂纹].（分句法）这种状态经过循环往复后，疲劳将导致裂纹图案形成。这被认为是热裂纹。Diebreakage[’brekɪdʒ断裂]orcrackingisduetomechanicalfatigueandoccursincaseswherethediesareoverloadedandlocalstressesarehigh.（分句法）模具断裂或产生裂纹是机械疲劳的缘故，发生在模具超载和局部应力高的地方。Thediesaresubjectedto[受到]alternatingstresses[交变应力]duetoloadingandunloadingduringthedeformationprocess,andthiscausescrackinitiationandeventualfailure．（直译法）模具由于在形变过程中的加载、卸载而受到交变应力，这导致了裂纹发生和最终的破坏。Dielifeanddiefailurearegreatlyaffectedbythemechanicalpropertiesofthediematerialsundertheconditionsthatexistinagivendeformationprocess.（状语前置）在给定的变形进程具有的条件下，模具的寿命及其失效很大程度上受模具材料机械性能的影响。Generally,thepropertiesthataremostsignificantdependontheprocesstemperature.Thus,diematerialsusedincoldformingprocessesarequitedifferentfromthoseusedinhotforming.（直译法+定语前置）通常，影响最大的特性取决于加工温度。因此，用冷成形加工而成的模具材料与用热成形加工而成的模具材料大有不同。Thedesignandmanufactureofdiesandtheselectionofdiematerialsareveryimportantintheproductionofdiscretepartsbyuseofmetalformingprocesses.（状语前置）对于用金属成形加工生产的单个部件，模具的设计和制造及模具材料的选择非常重要。Thediesmustbemadebymodernmanufacturingmethodsfromappropriatediematerialsinordertoprovideacceptabledielifeatareasonablecost.（逆序法）为了以合理的成本维持可接受的模具寿命，（上述的）模具必须用适当的模具材料经现代制造方法制成。Oftentheeconomicsuccessofaformingprocessdependsondielifeanddiecostsperpieceproduced.（直译法）通常，一个成形加工过程经济上的成功取决于模具寿命和生产每件模具的成本。Foragivenapplication,selectionoftheappropriatediematerialdependsonthreetypesofvariables:（直译法）对于给定的应用，模具材料的恰当选择取决于（以下）三种变量：(a)Variablesrelatedtotheprocessitself,includingfactorssuchassizeofthediecavity,typeofmachineusedanddeformationspeed,initialstocksizeandtemperature,dietemperaturetobeused,lubrication,productionrateandnumberofpartstobeproduced.（a）与加工工艺本身相关的变量，包括模腔尺寸、所用机器类型和变形速度，毛坯尺寸和温度，要用的模具温度、润滑、生产率和要生产的零件数量。(b)Variablesrelatedtothetypeofdieloading,includingspeedofloading,i.e.,impactorgradualcontacttimebetweendiesanddeformingmetal(thiscontacttimeisespeciallyimportantinhotforming),maximumloadandpressureonthedies,maximumandminimumdietemperatures,andnumberofloadingcyclestowhichthedieswillbesubjected．（b）与模具加载类型相关的变量，包括加载速度，即模具和变形中的金属冲击或者逐渐接触的时间（这段接触时间在热成型中尤为重要），模具上的最大荷载和压力，模具的最高和最低温度，以及模具将受到的加载循环次数。(c)Mechanicalpropertiesofthediematerial,includinghardenability,impactstrength,hotstrength(ifhotformingisconsidered)andresistancetothermalandmechanicalfatigue.（c）模具材料的物理特性，包括硬度，冲击强度，热强度（若考虑热成形的话），抗热性和抵抗机械疲劳的性能。G2ColdworkingandHotWorkingTheaboveconsiderationsprovidethebasisforclassificationofforgingtemperatureranges,namely,hotworking(hotforging)andcoldworking(coldforging).前面的想法给我们提供了用锻造温度范围进行分类的依据，也就是热加工（热锻造）和冷加工（冷锻造）。Hotworkingisconsideredtobeplasticdeformationthatisaccomplishedabovetherecrystallization[再结晶]temperature.热加工被定义为是在高于再结晶温度的温度下完成的塑性变形。Theuseoftheterm“hotworking”usuallyimpliesthatthematerialisheated—butnotalways.Forexample,therecrystallization[再结晶]ofleadtakesplaceatverylowtemperatures.热加工这个词的使用通常意味着材料是被加热的，但也有例外。举个例子，铅的再结晶过程就发生在非常低的温度下。Bytheabovedefinition,lead[铅]forgedatroomtemperatureisbeinghotworked.根据前面的定义，铅在室温下的锻造过程就是热加工。Coldworkingisdefinedasplasticdeformationbelowtherecrystallization[再结晶]temperature.冷加工的定义是在低于再结晶温度的温度下发生的塑