钢铁热处理中英文对照外文翻译文献

中英文对照外文翻译(文档含英文原文和中文翻译)原文:HeatTreatmentofSteelTypesofHeatTreatingOperations FiveOperationsaredetailedinthislessonasthebasisofheattreatment.Explanationsoftheseoperationsfollow.Fullannealing Fullannealingistheprocessofsofteningsteelbyaheatingandcoolingcycle,sothatitmaybebentorcuteasily.Inannealing,steelisheatedaboveatransformationtemperatureandcooledveryslowlyafterithasreachedasuitabletemperature.Thedistinguishingcharacteristicsoffullannealingare:(a)temperatureabovethecriticaltemperatureand(b)veryslowcooling,usuallyinthefurnace.Normalizing Normalizingisidenticalwithannealing,exceptthatthesteelisaircooled;thisismuchfasterthancoolinginafurnace.Steelisnormalizedtorefinegrainsize,makeitsstructuremoreuniform,ortoimprovemachinability.Hardening Hardeningiscarriedoutyquenchingasteel,thatis,coolingitrapidlyfromatemperatureabovethetransformationtemperature.Steelisquenchedinwaterorbrineforthemostrapidcooling,inoilforsomealloysteels,andinairforcertainhigheralloysteels.Aftersteelisquenched,itisusuallyveryhardandbrittle;itmayevencrackifdropped.Tomakethesteelmoreductile,itmustbetempered.Tempering Temperingconsistesofreheatingaquenchedsteeltoasuitabletemperaturebelowthetransformationtemperatureforanappropriatetimeandcoolingbacktoroomtemperature.Howthisprocessmakessteeltoughwillbediscussedlater.Stressrelieving Stressrelievingistheheatingofsteeltoatemperaturebelowthetransformationtemperature,asintempering,butisdoneprimarilytorelieveinternalstressandthuspreventdistortionorcrackingduringmachining.Thisissometimescalledprocessannealing.ReasonsforHeatTreating Heattreatmentofsteelisusuallyintendedtoaccomplishanyoneofthefollowingobjectives:●Removestressesinducedbycoldworkingortoremovestressessetupbynonuniformcoolingofhotmetalobjects;●Refinethegrainstructureofhotworkedsteelswhichmayhavedevelopedcoarsegrainsize;●Securethepropergrainstructure;●Decreasethehardnessandincreasetheductility;●Increasethehardnesssoastoincreaseresistancetowearortoenablethesteeltowithstandmoreserviceconditions;●Increasethetoughness;thatis,toproduceasteelhavingbothahightensilestrengthandgoodductility,enablingittowithstandhighimpact;●Improvethemachinability;●Improvetheelectricalproperties;●Changeormodifythemagneticpropertiesofsteel.HeatTreatment Thehardestconditionforanygivenssteelisobtainedbyquenchingtoafullymartensiticstructure.Sincehardnessisdirectlyrelatedtostrength,asteelcomposedof100%martensiteisatitsstrongestpossiblecondition.However,strengthisnottheonlypropertythatmustbeconsideredintheapplicationofsteelparts.Ductilitymaybeequallyimportant.Tempering Ductilityistheabilityofametaltochangeshapebeforeitbreaks.Fleshlyquenchedmartensiteishardbutnotductile;infact,itisverybrittle.Temperingisneededtoimpartductilitytothemartensite,usuallyatasmellsacrificeinstrength.Inaddition,temperinggreatlyincreasestheresistanceofmartensitetoshockloading.Theeffectoftemperingmaybeillustratedasfollows.Iftheheadofahammerwerequenchedtoafullymartensiticstructure,itprobablywouldcrackafterthefirstfewblows.Temperingduringmanufactureofthehammerimpartsshockresistancewithonlyaslightdecreaseinhardness.Temperingisaccomplishedbyheatingaquenchedperttosomepointbelowthetransformationtemperature,andholdingitatthistemperatureforanhourormore,dependingonitssize.Moststeelsaretemperedbetween205and5,950C.Ashighertemperaturesareemployed,toughnessorshockresistanceofthesteelisincreased,butthehardnessandstrengthdecrease.Annealing thetwo-stageheattreatingprocessofquenchingandtemperingisdesignedtoproducehighstrengthsteelcapableofresistingshockanddeformationwithoutbreaking.Ontheotherhand,theannealingprocessisintendtomakesteeleasiertodeformofmachine.Inmanufacturingsteelproducts,machiningandseverebendingoperationsareoftenemployed.Eventemperedsteelmaynotcutorbendveryeasilyandannealingisoftennecessary.Processannealing Processannealingconsistsofheatingsteeltoatemperaturejustbelowthelowesttransformationtemperatureforashorttime.Thismakesthesteeleasiertoform.Thisheattreatmentiscommonlyappliedinthesheetandwireindustries,andthetemperaturesgenerallyusedarefrom550to650oC.Fullannealing Processannealing,wheresteelisheated50to100oCabovethethirdtransformationtemperatureforhypoeutectoidsteels,andabovethelowesttransformationtemperatureforhypereutectoidsteels,andslowcooled,makesthesteelmucheasiertocut,aswellasbend.Infullannealing,coolingmusttakeplaceveryslowlysothatacoarsepearliteisformed.Showcoolingisnotessentialforprocessannealing,sinceanycoolingratefromtemperaturesbelowthelowesttransformationtemperaturewillresultinthesamemicrostructureandhardness.Duringcolddeformation,steelhasatendencytohardenindeformedareas,makingitmoredifficulttobendandliabletobreakage.Alternatedeformingandannealingoperationsareperformedonmostmanufacturedsteelproducts.Normalizing Theprocessofnormalizingconsistsofheatingtoatemperatureabovethethirdtransformationtemperatureandallowingtheperttocoolinstillair.Theactualtemperaturerequiredforthisdependsonthecompositionofthesteel,butisusuallyaround870oC.Actually,thetermnormalizedoesnotdescribethepurpose.Theprocessmightbemoreaccuratelydescribedasahomogenizingorgrain-refiningtreatment.Withinanypieceofsteel,thecompositionisusuallynotuniformthroughout.Thatis,oneareamayhavemorecarbonthantheareaadjacenttoit.Thesecompositionaldifferencesaffectthewayinwhichthesteelwillrespondtheattreatment.Ifitisheatedtoahightemperature,thecarboncanreadilydiffusethroughout,andtheresultisareasonablyuniformcompositionfromoneareatonext.Thesteelisthenmorehomogeneousandwillrespondtotheheattreatmentinamoreuniformway.Becauseofcharacteristicsinherentincaststeel,thenormalizingtreatmentismorefrequentlyappliedtoingotspriortoworking,andtosteelcastingsandforgingspriortohardening.StressRelieving Whenametalisheated,expansionoccurswhichismoreorlessproportionaltothetemperaturerise.Uponcoolingmetal,thereversereactiontakesplace.Thatis,acontractionisobserved.Whenasteelbarorplateisheatedatonepointmorethanatanother,asinweldingorduringforging,internalstressaresetup.Duringheating,expansionoftheheatedareacannottakeplaceunhindered,andittendstodeform.Oncooling,contractionispreventedfromtakingplacebytheunyieldingcoldmetalsurroundingtheheatedarea.Theforcesattemptingtocontractthemetalarenotrelieved,andwhenthemetaliscoldagain,theforcesremainasinternalstresses.Stressesalsoresultfromvolumechanges,whichaccompanymetaltransformationsandprecipitation.Internalorresidualstressesarebadbecausetheymaycausewarpingofsteelpartswhentheyaremachined.Torelievethesestresses,steelisheatedtoaround595oC,assumingthattheentirepertisheateduniformly,thencooledslowlybacktoroomtemperature.Thisprocedureiscalledstressreliefannealing,ormerelystressrelieving.译文：钢的热处理各种类型的热处理  本单元详细介绍了五种热处理的基本方法。这些方法如下。完全退火 完全退火是利用冷热循环使钢铁硬度下降的过程，之后它就容易被切割和弯曲。在退火时，钢被加热到相变温度上并且达到一个合适温度后就缓慢冷却。完全退火的区别其他退火的特点是：（a）温度高于临界温度（b）缓慢冷却，通常是炉冷。正火 正火与退火相同，除了钢铁的正火是空冷，这样将比在炉中冷却的快。金属进行正火是为了细化精粒，使它的组织更加规律，或提高它的机械加工性能。淬火 淬火就是钢淬火，它是将钢从临界温度以上迅速冷却。钢一般是在水中或者卤水中进行淬火，这是为了快速冷却，而另外一些合金钢用油冷，以及某些高等合金钢要用空冷。钢催后之后，一般会很硬很脆，有可能在落地后碎裂。为了是钢有更高的韧性它，必须还要经过回火回火 回火是将淬火过的钢再次加热到转变温度以下一定时间后再冷却到室温的热处理工艺。这个过程是如何使钢有高硬度之后将会讨论。去应力 去应力是加热钢到转变温度一下，如同回火一样，但这样做主要是为了消除内应力和防止在机械加工的过程中的扭曲和变形。有时候我们也称这个过程叫做退火。热处理的原因 钢的热处理经常是为了完善如下几个方面：消除在冷却过程中产生的应力和消除热金属处理中的应力。细化晶粒组织，钢可能在热加工过后会产生粗大的晶粒。获得稳定的适当的晶粒结构降低硬度，提高塑性。增加硬度以提高抗磨损能力或者使金属能够承受更多条件环境。、增加韧性，这样一来，可以使钢同时拥有高拉伸性和好的延展性，使它能承受高程度的碰撞。提高切削性能。提高导电性。改变钢的磁性。热处理 对于任何一种钢而言，最困难的是获得马氏体。由于硬度和强度有直接关系，钢由百分之百的马氏体组成时它处于最大强度状态。然而，强度并不是钢在应用中唯一考虑的性质，延展性同样重要。回火 可塑性是指金属在其破裂前改变形状的能力。马氏体本身具有很高硬度但延展性不高，而且易碎。回火是被用作使马氏体具有良好的可塑性，往往是牺牲了一小部分的强度。此外，回火处理大大增加了马氏体抵抗冲击负荷的能力。回火的影响以下举例说明。如果一个锤子的头经过淬火变成完全马氏体的结构，它很可能在最初的几次打击后破裂。锤子的韧性在回火过程中获得提高而仅仅伴随硬度稍微降低。回火是经过淬火后急速冷却到相变温度下某一点的过程，并且保持这个温度一个小时或者更久，这个温度由钢的尺寸来决定。大多数钢的回火温度在205℃~595℃。随着温度的提高，钢的韧性和抗冲击强度也增强，但是硬度和强度下降。退火 在回火和淬火这两个工艺阶段，其目的是能制造可以抵抗高冲击强度和磨损变形的高强度钢材。令一方面，退火工艺的目的是使得钢材容易加工和变形。在钢制品的机械加工中，机械制造产生的弯曲是非常常见的。经过回火的钢材可能不容易被切割和弯曲，所以回火往往是必要的。退火工艺 退火工艺需要加热钢材到最低相变温度下一段时间。这使钢更容易成型。这种热处理往往被用于钢铁和电线产业，其工艺温度一般在550~650℃。完全退火 完全退火，就是把钢材加热到第三转变温度以上50~100℃使之成为亚共析钢，或者加热到最低转变温度以上为过共析钢，经过缓慢冷却，使钢材容易被切削和弯曲。在完全退火中，冷却必须进行的很缓慢从而使之形成粗糙的珠光体。缓慢冷却并不是退火过程中必不可少的，这是由于加热到最低的转变温度以下后，任何冷却速度都会导致钢材形成同样的结构和硬度。在冷变形中，钢材有着在形变区域内变硬的趋势，使之更难弯曲和容易被损坏。在大多数的机械加工钢材中，交替变形和退火都被使用缺一不可。正火 正火过程包括把钢材加热到第三温度以上并使其在空气中冷却。正火实际需要的温度取决于钢的组成成分，但通常在870℃左右。实际上，这个过程并不能描述其目的。把这个过程描述为均匀或晶粒细化处理可能会更准确些。做一小块钢材上，它的组成通常是不一样的。也就是说，某一个区域上会比它的领域含有更多的碳。这些成分的差异影响着钢的热处理。如果加热到一个较高的温度，碳很可能迅速扩散到各处，结果就是每一区域的碳都是均匀的。这时的钢材比较匀质并且更易于热处理。由于铸铁的固有性质，被加工前的铸铁块往往更需要频繁的正火加工，然后才是进行浇铸和变硬。去应力 当金属被加热时，它就会产生膨胀，膨胀的多少与加工温度成比例关系。如果降温，金属就会发生相反的反应。即注意到钢材的缩小。当钢的某一点加热的温度高于其它地方时，就像焊接或锻造一样，那一点就会产生内应力，。加热过程中，膨胀的区域不能被诛之，并且它会趋向于变形。冷却时，高温区域的缩小会被周围的冷区域的 材料 关于××同志的政审材料调查表环保先进个人材料国家普通话测试材料农民专业合作社注销四查四问剖析材料 阻止。那些使金属压缩的应力并没有减弱，当金属在次冷却时，这个力与内应力一样不变。压力往往随着体积改变，这种变化伴随着材料的转变和析出。内应力和残余应力都是有害的，这是因为在加工时它们可能会导致钢铁部件的变形。为消除这些应力，钢材要加热到595℃左右，确定整个材料被加热均匀，再慢慢冷却到室温。这种程序被称为去应力退火，或者为去应力。