外文資料原文與譯文中英文對照外文翻譯(文檔含英文原文和中文翻譯)原文:HeatTreatmentofSteelTypesofHeatTreatingOperationsFiveOperationsaredetailedinthislessonasthebasisofheattreatment.Explanationsoftheseoperationsfollow.FullannealingFullannealingistheprocessofsofteningsteelbyaheatingandcoolingcycle,sothatitmaybebentorcuteasily.Inannealing,steelisheatedaboveatransformationtemperatureandcooledveryslowlyafterithasreachedasuitabletemperature.Thedistinguishingcharacteristicsoffullannealingare:(a)temperatureabovethecriticaltemperatureand(b)veryslowcooling,usuallyinthefurnace.NormalizingNormalizingisidenticalwithannealing,exceptthatthesteelisaircooled;thisismuchfasterthancoolinginafurnace.Steelisnormalizedtorefinegrainsize,makeitsstructuremoreuniform,ortoimprovemachinability.HardeningHardeningiscarriedoutyquenchingasteel,thatis,coolingitrapidlyfromatemperatureabovethetransformationtemperature.Steelisquenchedinwaterorbrineforthemostrapidcooling,inoilforsomealloysteels,andinairforcertainhigheralloysteels.Aftersteelisquenched,itisusuallyveryhardandbrittle;itmayevencrackifdropped.Tomakethesteelmoreductile,itmustbetempered.TemperingTemperingconsistesofreheatingaquenchedsteeltoasuitabletemperaturebelowthetransformationtemperatureforanappropriatetimeandcoolingbacktoroomtemperature.Howthisprocessmakessteeltoughwillbediscussedlater.StressrelievingStressrelievingistheheatingofsteeltoatemperaturebelowthetransformationtemperature,asintempering,butisdoneprimarilytorelieveinternalstressandthuspreventdistortionorcrackingduringmachining.Thisissometimescalledprocessannealing.ReasonsforHeatTreatingHeattreatmentofsteelisusuallyintendedtoaccomplishanyoneofthefollowingobjectives:Removestressesinducedbycoldworkingortoremovestressessetupbynonuniformcoolingofhotmetalobjects;Refinethegrainstructureofhotworkedsteelswhichmayhavedevelopedcoarsegrainsize;Securethepropergrainstructure;Decreasethehardnessandincreasetheductility;Increasethehardnesssoastoincreaseresistancetowearortoenablethesteeltowithstandmoreserviceconditions;Increasethetoughness;thatis,toproduceasteelhavingbothahightensilestrengthandgoodductility,enablingittowithstandhighimpact;Improvethemachinability;Improvetheelectricalproperties;Changeormodifythemagneticpropertiesofsteel.HeatTreatmentThehardestconditionforanygivenssteelisobtainedbyquenchingtoafullymartensiticstructure.Sincehardnessisdirectlyrelatedtostrength,asteelcomposedof100%martensiteisatitsstrongestpossiblecondition.However,strengthisnottheonlypropertythatmustbeconsideredintheapplicationofsteelparts.Ductilitymaybeequallyimportant.TemperingDuctilityistheabilityofametaltochangeshapebeforeitbreaks.Fleshlyquenchedmartensiteishardbutnotductile;infact,itisverybrittle.Temperingisneededtoimpartductilitytothemartensite,usuallyatasmellsacrificeinstrength.Inaddition,temperinggreatlyincreasestheresistanceofmartensitetoshockloading.Theeffectoftemperingmaybeillustratedasfollows.Iftheheadofahammerwerequenchedtoafullymartensiticstructure,itprobablywouldcrackafterthefirstfewblows.Temperingduringmanufactureofthehammerimpartsshockresistancewithonlyaslightdecreaseinhardness.Temperingisaccomplishedbyheatingaquenchedperttosomepointbelowthetransformationtemperature,andholdingitatthistemperatureforanhourormore,dependingonitssize.Moststeelsaretemperedbetween205and5,950C.Ashighertemperaturesareemployed,toughnessorshockresistanceofthesteelisincreased,butthehardnessandstrengthdecrease.Annealingthetwo-stageheattreatingprocessofquenchingandtemperingisdesignedtoproducehighstrengthsteelcapableofresistingshockanddeformationwithoutbreaking.Ontheotherhand,theannealingprocessisintendtomakesteeleasiertodeformofmachine.Inmanufacturingsteelproducts,machiningandseverebendingoperationsareoftenemployed.Eventemperedsteelmaynotcutorbendveryeasilyandannealingisoftennecessary.ProcessannealingProcessannealingconsistsofheatingsteeltoatemperaturejustbelowthelowesttransformationtemperatureforashorttime.Thismakesthesteeleasiertoform.Thisheattreatmentiscommonlyappliedinthesheetandwireindustries,andthetemperaturesgenerallyusedarefrom550to650oC.FullannealingProcessannealing,wheresteelisheated50to100oCabovethethirdtransformationtemperatureforhypoeutectoidsteels,andabovethelowesttransformationtemperatureforhypereutectoidsteels,andslowcooled,makesthesteelmucheasiertocut,aswellasbend.Infullannealing,coolingmusttakeplaceveryslowlysothatacoarsepearliteisformed.Showcoolingisnotessentialforprocessannealing,sinceanycoolingratefromtemperaturesbelowthelowesttransformationtemperaturewillresultinthesamemicrostructureandhardness.Duringcolddeformation,steelhasatendencytohardenindeformedareas,makingitmoredifficulttobendandliabletobreakage.Alternatedeformingandannealingoperationsareperformedonmostmanufacturedsteelproducts.NormalizingTheprocessofnormalizingconsistsofheatingtoatemperatureabovethethirdtransformationtemperatureandallowingtheperttocoolinstillair.Theactualtemperaturerequiredforthisdependsonthecompositionofthesteel,butisusuallyaround870oC.Actually,thetermnormalizedoesnotdescribethepurpose.Theprocessmightbemoreaccuratelydescribedasahomogenizingorgrain-refiningtreatment.Withinanypieceofsteel,thecompositionisusuallynotuniformthroughout.Thatis,oneareamayhavemorecarbonthantheareaadjacenttoit.Thesecompositionaldifferencesaffectthewayinwhichthesteelwillrespondtheattreatment.Ifitisheatedtoahightemperature,thecarboncanreadilydiffusethroughout,andtheresultisareasonablyuniformcompositionfromoneareatonext.Thesteelisthenmorehomogeneousandwillrespondtotheheattreatmentinamoreuniformway.Becauseofcharacteristicsinherentincaststeel,thenormalizingtreatmentismorefrequentlyappliedtoingotspriortoworking,andtosteelcastingsandforgingspriortohardening.StressRelievingWhenametalisheated,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.

譯文：鋼的熱處理各種類型的熱處理本單元詳細介紹了五種熱處理的基本方法。這些方法如下。完全退火完全退火是利用冷熱循環(huán)使鋼鐵硬度下降的過程，之后它就容易被切割和彎曲。在退火時，鋼被加熱到相變溫度上并且達到一個合適溫度后就緩慢冷卻。完全退火的區(qū)別其他退火的特點是：（a）溫度高于臨界溫度（b）緩慢冷卻，通常是爐冷。正火正火與退火相同，除了鋼鐵的正火是空冷，這樣將比在爐中冷卻的快。金屬進行正火是為了細化精粒，使它的組織更加規(guī)律，或提高它的機械加工性能。淬火淬火就是鋼淬火，它是將鋼從臨界溫度以上迅速冷卻。鋼一般是在水中或者鹵水中進行淬火，這是為了快速冷卻，而另外一些合金鋼用油冷，以及某些高等合金鋼要用空冷。鋼催后之后，一般會很硬很脆，有可能在落地后碎裂。為了是鋼有更高的韌性它，必須還要經(jīng)過回火回火回火是將淬火過的鋼再次加熱到轉(zhuǎn)變溫度以下一定時間后再冷卻到室溫的熱處理工藝。這個過程是如何使鋼有高硬度之后將會討論。去應力去應力是加熱鋼到轉(zhuǎn)變溫度一下，如同回火一樣，但這樣做主要是為了消除內(nèi)應力和防止在機械加工的過程中的扭曲和變形。有時候我們也稱這個過程叫做退火。熱處理的原因鋼的熱處理經(jīng)常是為了完善如下幾個方面：消除在冷卻過程中產(chǎn)生的應力和消除熱金屬處理中的應力。細化晶粒組織，鋼可能在熱加工過后會產(chǎn)生粗大的晶粒。獲得穩(wěn)定的適當?shù)木Я＝Y(jié)構(gòu)降低硬度，提高塑性。增加硬度以提高抗磨損能力或者使金屬能夠承受更多條件環(huán)境。、增加韌性，這樣一來，可以使鋼同時擁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。提高導電性。改變鋼的磁性。熱處理對于任何一種鋼而言，最困難的是獲得馬氏體。由于硬度和強度有直接關(guān)系，鋼由百分之百的馬氏體組成時它處于最大強度狀態(tài)。然而，強度并不是鋼在應用中唯一考慮的性質(zhì)，延展性同樣重要?；鼗鹂伤苄允侵附饘僭谄淦屏亚案淖冃螤畹哪芰?。馬氏體本身具有很高硬度但延展性不高，而且易碎。回火是被用作使馬氏體具有良好的可塑性，往往是犧牲了一小部分的強度。此外，回火處理大大增加了馬氏體抵抗沖擊負荷的能力?；鼗鸬挠绊懸韵屡e例說明。如果一個錘子的頭經(jīng)過淬火變成完全馬氏體的結(jié)構(gòu)，它很可能在最初的幾次打擊后破裂。錘子的韌性在回火過程中獲得提高而僅僅伴隨硬度稍微降低?；鼗鹗墙?jīng)過淬火后急速冷卻到相變溫度下某一點的過程，并且保持這個溫度一個小時或者更久，這個溫度由鋼的尺寸來決定。大多數(shù)鋼的回火溫度在205℃~595℃。隨著溫度的提高，鋼的韌性和抗沖擊強度也增強，但是硬度和強度下降。退火在回火和淬火這兩個工藝階段，其目的是能制造可以抵抗高沖擊強度和磨