湖南工院畢業(yè)設(shè)計論文外文翻譯外文題目HEATTREATMENTOFMETAL譯文題目金屬熱處理系部機械工程系專業(yè)班級機械設(shè)計制造及其自動化學(xué)生姓名指導(dǎo)教師完成時間原文HEATTREATMENTOFMETALTHEGENERALLYACCEPTEDDEFINITIONFORHEATTREATINGMETALSANDMETALALLOYSIS“HEATINGANDCOOLINGASOLIDMETALORALLOYINAWAYSOASTOOBTAINSPECIFICCONDITIONSORPROPERTIES”HEATINGFORTHESOLEPURPOSEOFHOTWORKINGASINFORGINGOPERATIONSISEXCLUDEDFROMTHISDEFINITIONLIKEWISE，THETYPESOFHEATTREATMENTTHATARESOMETIMESUSEDFORPRODUCTSSUCHASGLASSORPLASTICSAREALSOEXCLUDEDFROMCOVERAGEBYTHISDEFINITIONTRANSFORMATIONCURVESTHEBASISFORHEATTREATMENTISTHETIMETEMPERATURETRANSFORMATIONCURVESORTTTCURVESWHERE，INASINGLEDIAGRAMALLTHETHREEPARAMETERSAREPLOTTEDBECAUSEOFTHESHAPEOFTHECURVES，THEYAREALSOSOMETIMESCALLEDCCURVESORSCURVESTOPLOTTTTCURVES，THEPARTICULARSTEELISHELDATAGIVENTEMPERATUREANDTHESTRUCTUREISEXAMINEDATPREDETERMINEDINTERVALSTORECORDTHEAMOUNTOFTRANSFORMATIONTAKENPLACEITISKNOWNTHATTHEEUTECTOIDSTEELT80UNDEREQUILIBRIUMCONDITIONSCONTAINS，ALLAUSTENITEABOVE723，WHEREASBELOW，ITISTHEPEARLITETOFORMPEARLITE，THECARBONATOMSSHOULDDIFFUSETOFORMCEMENTITETHEDIFFUSIONBEINGARATEPROCESS，WOULDREQUIRESUFFICIENTTIMEFORCOMPLETETRANSFORMATIONOFAUSTENITETOPEARLITEFROMDIFFERENTSAMPLES，ITISPOSSIBLETONOTETHEAMOUNTOFTHETRANSFORMATIONTAKINGPLACEATANYTEMPERATURETHESEPOINTSARETHENPLOTTEDONAGRAPHWITHTIMEANDTEMPERATUREASTHEAXESTHROUGHTHESEPOINTS，TRANSFORMATIONCURVESCANBEPLOTTEDASSHOWNINFIG1FOREUTECTOIDSTEELTHECURVEATEXTREMELEFTREPRESENTSTHETIMEREQUIREDFORTHETRANSFORMATIONOFAUSTENITETOPEARLITETOSTARTATANYGIVENTEMPERATURESIMILARLY，THECURVEATEXTREMERIGHTREPRESENTSTHETIMEREQUIREDFORCOMPLETINGTHETRANSFORMATIONBETWEENTHETWOCURVESARETHEPOINTSREPRESENTINGPARTIALTRANSFORMATIONTHEHORIZONTALLINESMSANDMFREPRESENTTHESTARTANDFINISHOFMARTENSITICTRANSFORMATIONCLASSIFICATIONOFHEATTREATINGPROCESSESINSOMEINSTANCES，HEATTREATMENTPROCEDURESARECLEARCUTINTERMSOFTECHNIQUEANDAPPLICATIONWHEREASINOTHERINSTANCES，DESCRIPTIONSORSIMPLEEXPLANATIONSAREINSUFFICIENTBECAUSETHESAMETECHNIQUEFREQUENTLYMAYBEUSEDTOOBTAINDIFFERENTOBJECTIVESFOREXAMPLE,STRESSRELIEVINGANDTEMPERINGAREOFTENACCOMPLISHEDWITHTHESAMEEQUIPMENTANDBYUSEOFIDENTICALTIMEANDTEMPERATURECYCLESTHEOBJECTIVES，HOWEVER，AREDIFFERENTFORTHETWOPROCESSESTHEFOLLOWINGDESCRIPTIONSOFTHEPRINCIPALHEATTREATINGPROCESSESAREGENERALLYARRANGEDACCORDINGTOTHEIRINTERRELATIONSHIPSNORMALIZINGCONSISTSOFHEATINGAFERROUSALLOYTOASUITABLETEMPERATUREUSUALLY50FTO100FOR28TO56ABOVEITSSPECIFICUPPERTRANSFORMATIONTEMPERATURETHISISFOLLOWEDBYCOOLINGINSTILLAIRTOATLEASTSOMETEMPERATUREWELLBELOWITSTRANSFORMATIONTEMPERATURERANGEFORLOWCARBONSTEELS,THERESULTINGSTRUCTUREANDPROPERTIESARETHESAMEASTHOSEACHIEVEDBYFULLANNEALING；FORMOSTFERROUSALLOYS,NORMALIZINGANDANNEALINGARENOTSYNONYMOUSNORMALIZINGUSUALLYISUSEDASACONDITIONINGTREATMENT,NOTABLYFORREFININGTHEGRAINSOFSTEELSTHATHAVEBEENSUBJECTEDTOHIGHTEMPERATURESFORFORGINGOROTHERHOTWORKINGOPERATIONSTHENORMALIZINGPROCESSUSUALLYISSUCCEEDEDBYANOTHERHEATTREATINGOPERATIONSUCHASAUSTENITIZINGFORHARDENING,ANNEALING,ORTEMPERINGANNEALINGISAGENERICTERMDENOTINGAHEATTREATMENTTHATCONSISTSOFHEATINGTOANDHOLDINGATASUITABLETEMPERATUREFOLLOWEDBYCOOLINGATASUITABLERATEITISUSEDPRIMARILYTOSOFTENMETALLICMATERIALS,BUTALSOTOSIMULTANEOUSLYPRODUCEDESIREDCHANGESINOTHERPROPERTIESORINMICROSTRUCTURETHEPURPOSEOFSUCHCHANGESMAYBE,BUTISNOTCONFINEDTO,IMPROVEMENTOFMACHINABILITY,FACILITATIONOFCOLDWORKKNOWNASINPROCESSANNEALING,IMPROVEMENTOFMECHANICALORELECTRICALPROPERTIES,ORTOINCREASEDIMENSIONALSTABILITYWHENAPPLIEDSOLELYTORELIVESTRESSES,ITCOMMONLYISCALLEDSTRESSRELIEFANNEALING,SYNONYMOUSWITHSTRESSRELIEVINGWHENTHETERM“ANNEALING”ISAPPLIEDTOFERROUSALLOYSWITHOUTQUALIFICATION,FULLANNEALINGISAPPLIEDTHISISACHIEVEDBYHEATINGABOVETHEALLOYSTRANSFORMATIONTEMPERATURE,THENAPPLYINGACOOLINGCYCLEWHICHPROVIDESMAXIMUMSOFTNESSTHISCYCLEMAYVARYWIDELY,DEPENDINGONCOMPOSITIONANDCHARACTERISTICSOFTHESPECIFICALLOYQUENCHINGISARAPIDCOOLINGOFASTEELORALLOYFROMTHEAUSTENITIZINGTEMPERATUREBYIMMERSINGTHEWORKPIECEINALIQUIDORGASEOUSMEDIUMQUENCHINGMEDIUMCOMMONLYUSEDINCLUDEWATER,5BRINE,5CAUSTICINANAQUEOUSSOLUTION,OIL,POLYMERSOLUTIONS,ORGASUSUALLYAIRORNITROGENSELECTIONOFAQUENCHINGMEDIUMDEPENDSLARGELYONTHEHARDENABILITYOFMATERIALANDTHEMASSOFTHEMATERIALBEINGTREATINGPRINCIPALLYSECTIONTHICKNESSTHECOOLINGCAPABILITIESOFTHEABOVELISTEDQUENCHINGMEDIAVARYGREATLYINSELECTINGAQUENCHINGMEDIUM,ITISBESTTOAVOIDASOLUTIONTHATHASMORECOOLINGPOWERTHANISNEEDEDTOACHIEVETHERESULTS,THUSMINIMIZINGTHEPOSSIBILITYOFCRACKINGANDWARPOFTHEPARTSBEINGTREATEDMODIFICATIONSOFTHETERMQUENCHINGINCLUDEDIRECTQUENCHING,FOGQUENCHING,HOTQUENCHING,INTERRUPTEDQUENCHING,SELECTIVEQUENCHING,SPRAYQUENCHING,ANDTIMEQUENCHINGTEMPERINGINHEATTREATINGOFFERROUSALLOYS,TEMPERINGCONSISTSOFREHEATINGTHEAUSTENITIZEDANDQUENCHHARDENEDSTEELORIRONTOSOMEPRESELECTEDTEMPERATURETHATISBELOWTHELOWERTRANSFORMATIONTEMPERATUREGENERALLYBELOW1300OR705TEMPERINGOFFERSAMEANSOFOBTAININGVARIOUSCOMBINATIONSOFMECHANICALPROPERTIESTEMPERINGTEMPERATURESUSEDFORHARDENEDSTEELSAREOFTENNOHIGHERTHAN300150THETERM“TEMPERING”SHOULDNOTBECONFUSEDWITHEITHERPROCESSANNEALINGORSTRESSRELIEVINGEVENTHOUGHTIMEANDTEMPERATURECYCLESFORTHETHREEPROCESSESMAYBETHESAME,THECONDITIONSOFTHEMATERIALSBEINGPROCESSEDANDTHEOBJECTIVESMAYBEDIFFERENTSTRESSRELIEVINGLIKETEMPERING,STRESSRELIEVINGISALWAYSDONEBYHEATINGTOSOMETEMPERATUREBELOWTHELOWERTRANSFORMATIONTEMPERATUREFORSTEELSANDIRONSFORNONFERROUSMETALS,THETEMPERATUREMAYVARYFROMSLIGHTLYABOVEROOMTEMPERATURETOSEVERALHUNDREDDEGREES,DEPENDINGONTHEALLOYANDTHEAMOUNTOFSTRESSRELIEFTHATISDESIREDTHEPRIMARYPURPOSEOFSTRESSRELIEVINGISTORELIEVESTRESSESTHATHAVEBEENIMPARTEDTOTHEWORKPIECEFROMSUCHPROCESSESASFORMING,ROLLING,MACHININGORWELDINGTHEUSUALPROCEDUREISTOHEATWORKPIECETOTHEPREESTABLISHEDTEMPERATURELONGENOUGHTOREDUCETHERESIDUALSTRESSESTHISISATIMEANDTEMPERATUREDEPENDENTOPERATIONTOANACCEPTABLELEVELTHISISFOLLOWEDBYCOOLINGATARELATIVELYSLOWRATETOAVOIDCREATIONOFNEWSTRESSESTHEGENERALLYACCEPTEDDEFINITIONFORHEATTREATINGMETALSANDMETALALLOYSIS“HEATINGANDCOOLINGASOLIDMETALORALLOYINAWAYSOASTOOBTAINSPECIFICCONDITIONSORPROPERTIES”HEATINGFORTHESOLEPURPOSEOFHOTWORKINGASINFORGINGOPERATIONSISEXCLUDEDFROMTHISDEFINITIONLIKEWISE，THETYPESOFHEATTREATMENTTHATARESOMETIMESUSEDFORPRODUCTSSUCHASGLASSORPLASTICSAREALSOEXCLUDEDFROMCOVERAGEBYTHISDEFINITIONTRANSFORMATIONCURVESTHEBASISFORHEATTREATMENTISTHETIMETEMPERATURETRANSFORMATIONCURVESORTTTCURVESWHERE，INASINGLEDIAGRAMALLTHETHREEPARAMETERSAREPLOTTEDBECAUSEOFTHESHAPEOFTHECURVES，THEYAREALSOSOMETIMESCALLEDCCURVESORSCURVESTOPLOTTTTCURVES，THEPARTICULARSTEELISHELDATAGIVENTEMPERATUREANDTHESTRUCTUREISEXAMINEDATPREDETERMINEDINTERVALSTORECORDTHEAMOUNTOFTRANSFORMATIONTAKENPLACEITISKNOWNTHATTHEEUTECTOIDSTEELT80UNDEREQUILIBRIUMCONDITIONSCONTAINS，ALLAUSTENITEABOVE723，WHEREASBELOW，ITISPEARLITETOFORMPEARLITE，THECARBONATOMSSHOULDDIFFUSETOFORMCEMENTITETHEDIFFUSIONBEINGARATEPROCESS，WOULDREQUIRESUFFICIENTTIMEFORCOMPLETETRANSFORMATIONOFAUSTENITETOPEARLITEFROMDIFFERENTSAMPLES，ITISPOSSIBLETONOTETHEAMOUNTOFTHETRANSFORMATIONTAKINGPLACEATANYTEMPERATURETHESEPOINTSARETHENPLOTTEDONAGRAPHWITHTIMEANDTEMPERATUREASTHEAXESTHROUGHTHESEPOINTS，TRANSFORMATIONCURVESCANBEPLOTTEDASSHOWNINFIG1FOREUTECTOIDSTEELTHECURVEATEXTREMELEFTREPRESENTSTHETIMEREQUIREDFORTHETRANSFORMATIONOFAUSTENITETOPEARLITETOSTARTATANYGIVENTEMPERATURESIMILARLY，THECURVEATEXTREMERIGHTREPRESENTSTHETIMEREQUIREDFORCOMPLETINGTHETRANSFORMATIONBETWEENTHETWOCURVESARETHEPOINTSREPRESENTINGPARTIALTRANSFORMATIONTHEHORIZONTALLINESMSANDMFREPRESENTTHESTARTANDFINISHOFMARTENSITICTRANSFORMATIONCLASSIFICATIONOFHEATTREATINGPROCESSESINSOMEINSTANCES，HEATTREATMENTPROCEDURESARECLEARCUTINTERMSOFTECHNIQUEANDAPPLICATIONWHEREASINOTHERINSTANCES，DESCRIPTIONSORSIMPLEEXPLANATIONSAREINSUFFICIENTBECAUSETHESAMETECHNIQUEFREQUENTLYMAYBEUSEDTOOBTAINDIFFERENTOBJECTIVESFOREXAMPLE,STRESSRELIEVINGANDTEMPERINGAREOFTENACCOMPLISHEDWITHTHESAMEEQUIPMENTANDBYUSEOFIDENTICALTIMEANDTEMPERATURECYCLESTHEOBJECTIVES，HOWEVER，AREDIFFERENTFORTHETWOPROCESSESTHEFOLLOWINGDESCRIPTIONSOFTHEPRINCIPALHEATTREATINGPROCESSESAREGENERALLYARRANGEDACCORDINGTOTHEIRINTERRELATIONSHIPSNORMALIZINGCONSISTSOFHEATINGAFERROUSALLOYTOASUITABLETEMPERATUREUSUALLY50FTO100FOR28TO56ABOVEITSSPECIFICUPPERTRANSFORMATIONTEMPERATURETHISISFOLLOWEDBYCOOLINGINSTILLAIRTOATLEASTSOMETEMPERATUREWELLBELOWITSTRANSFORMATIONTEMPERATURERANGEFORLOWCARBONSTEELS,THERESULTINGSTRUCTUREANDPROPERTIESARETHESAMEASTHOSEACHIEVEDBYFULLANNEALING；FORMOSTFERROUSALLOYS,NORMALIZINGANDANNEALINGARENOTSYNONYMOUSNORMALIZINGUSUALLYISUSEDASACONDITIONINGTREATMENT,NOTABLYFORREFININGTHEGRAINSOFSTEELSTHATHAVEBEENSUBJECTEDTOHIGHTEMPERATURESFORFORGINGOROTHERHOTWORKINGOPERATIONSTHENORMALIZINGPROCESSUSUALLYISSUCCEEDEDBYANOTHERHEATTREATINGOPERATIONSUCHASAUSTENITIZINGFORHARDENING,ANNEALING,ORTEMPERINGANNEALINGISAGENERICTERMDENOTINGAHEATTREATMENTTHATCONSISTSOFHEATINGTOANDHOLDINGATASUITABLETEMPERATUREFOLLOWEDBYCOOLINGATASUITABLERATEITISUSEDPRIMARILYTOSOFTENMETALLICMATERIALS,BUTALSOTOSIMULTANEOUSLYPRODUCEDESIREDCHANGESINOTHERPROPERTIESORINMICROSTRUCTURETHEPURPOSEOFSUCHCHANGESMAYBE,BUTISNOTCONFINEDTO,IMPROVEMENTOFMACHINABILITY,FACILITATIONOFCOLDWORKKNOWNASINPROCESSANNEALING,IMPROVEMENTOFMECHANICALORELECTRICALPROPERTIES,ORTOINCREASEDIMENSIONALSTABILITYWHENAPPLIEDSOLELYTORELIVESTRESSES,ITCOMMONLYISCALLEDSTRESSRELIEFANNEALING,SYNONYMOUSWITHSTRESSRELIEVINGWHENTHETERM“ANNEALING”ISAPPLIEDTOFERROUSALLOYSWITHOUTQUALIFICATION,FULLANNEALINGISAPPLIEDTHISISACHIEVEDBYHEATINGABOVETHEALLOYSTRANSFORMATIONTEMPERATURE,THENAPPLYINGACOOLINGCYCLEWHICHPROVIDESMAXIMUMSOFTNESSTHISCYCLEMAYVARYWIDELY,DEPENDINGONCOMPOSITIONANDCHARACTERISTICSOFTHESPECIFICALLOYQUENCHINGISARAPIDCOOLINGOFASTEELORALLOYFROMTHEAUSTENITIZINGTEMPERATUREBYIMMERSINGTHEWORKPIECEINALIQUIDORGASEOUSMEDIUMQUENCHINGMEDIUMCOMMONLYUSEDINCLUDEWATER,5BRINE,5CAUSTICINANAQUEOUSSOLUTION,OIL,POLYMERSOLUTIONS,ORGASUSUALLYAIRORNITROGENSELECTIONOFAQUENCHINGMEDIUMDEPENDSLARGELYONTHEHARDENABILITYOFMATERIALANDTHEMASSOFTHEMATERIALBEINGTREATINGPRINCIPALLYSECTIONTHICKNESSTHECOOLINGCAPABILITIESOFTHEABOVELISTEDQUENCHINGMEDIAVARYGREATLYINSELECTINGAQUENCHINGMEDIUM,ITISBESTTOAVOIDASOLUTIONTHATHASMORECOOLINGPOWERTHANISNEEDEDTOACHIEVETHERESULTS,THUSMINIMIZINGTHEPOSSIBILITYOFCRACKINGANDWARPOFTHEPARTSBEINGTREATEDMODIFICATIONSOFTHETERMQUENCHINGINCLUDEDIRECTQUENCHING,FOGQUENCHING,HOTQUENCHING,INTERRUPTEDQUENCHING,SELECTIVEQUENCHING,SPRAYQUENCHING,ANDTIMEQUENCHINGTEMPERINGINHEATTREATINGOFFERROUSALLOYS,TEMPERINGCONSISTSOFREHEATINGTHEAUSTENITIZEDANDQUENCHHARDENEDSTEELORIRONTOSOMEPRESELECTEDTEMPERATURETHATISBELOWTHELOWERTRANSFORMATIONTEMPERATUREGENERALLYBELOW1300OR705TEMPERINGOFFERSAMEANSOFOBTAININGVARIOUSCOMBINATIONSOFMECHANICALPROPERTIESTEMPERINGTEMPERATURESUSEDFORHARDENEDSTEELSAREOFTENNOHIGHERTHAN300150THETERM“TEMPERING”SHOULDNOTBECONFUSEDWITHEITHERPROCESSANNEALINGORSTRESSRELIEVINGEVENTHOUGHTIMEANDTEMPERATURECYCLESFORTHETHREEPROCESSESMAYBETHESAME,THECONDITIONSOFTHEMATERIALSBEINGPROCESSEDANDTHEOBJECTIVESMAYBEDIFFERENTSTRESSRELIEVINGLIKETEMPERING,STRESSRELIEVINGISALWAYSDONEBYHEATINGTOSOMETEMPERATUREBELOWTHELOWERTRANSFORMATIONTEMPERATUREFORSTEELSANDIRONSFORNONFERROUSMETALS,THETEMPERATUREMAYVARYFROMSLIGHTLYABOVEROOMTEMPERATURETOSEVERALHUNDREDDEGREES,DEPENDINGONTHEALLOYANDTHEAMOUNTOFSTRESSRELIEFTHATISDESIREDTHEPRIMARYPURPOSEOFSTRESSRELIEVINGISTORELIEVESTRESSESTHATHAVEBEENIMPARTEDTOTHEWORKPIECEFROMSUCHPROCESSESASFORMING,ROLLING,MACHININGORWELDINGTHEUSUALPROCEDUREISTOHEATWORKPIECETOTHEPREESTABLISHEDTEMPERATURELONGENOUGHTOREDUCETHERESIDUALSTRESSESTHISISATIMEANDTEMPERATUREDEPENDENTOPERATIONTOANACCEPTABLELEVELTHISISFOLLOWEDBYCOOLINGATARELATIVELYSLOWRATETOAVOIDCREATIONOFNEWSTRESSESTHEGENERALLYACCEPTEDDEFINITIONFORHEATTREATINGMETALSANDMETALALLOYSIS“HEATINGANDCOOLINGASOLIDMETALORALLOYINAWAYSOASTOOBTAINSPECIFICCONDITIONSORPROPERTIES”HEATINGFORTHESOLEPURPOSEOFHOTWORKINGASINFORGINGOPERATIONSISEXCLUDEDFROMTHISDEFINITIONLIKEWISE，THETYPESOFHEATTREATMENTTHATARESOMETIMESUSEDFORPRODUCTSSUCHASGLASSORPLASTICSAREALSOEXCLUDEDFROMCOVERAGEBYTHISDEFINITIONTRANSFORMATIONCURVESTHEBASISFORHEATTREATMENTISTHETIMETEMPERATURETRANSFORMATIONCURVESORTTTCURVESWHERE，INASINGLEDIAGRAMALLTHETHREEPARAMETERSAREPLOTTEDBECAUSEOFTHESHAPEOFTHECURVES，THEYAREALSOSOMETIMESCALLEDCCURVESORSCURVESTOPLOTTTTCURVES，THEPARTICULARSTEELISHELDATAGIVENTEMPERATUREANDTHESTRUCTUREISEXAMINEDATPREDETERMINEDINTERVALSTORECORDTHEAMOUNTOFTRANSFORMATIONTAKENPLACEITISKNOWNTHATTHEEUTECTOIDSTEELT80UNDEREQUILIBRIUMCONDITIONSCONTAINS，ALLAUSTENITEABOVE723，WHEREASBELOW，ITISPEARLITETOFORMPEARLITE，THECARBONATOMSSHOULDDIFFUSETOFORMCEMENTITETHEDIFFUSIONBEINGARATEPROCESS，WOULDREQUIRESUFFICIENTTIMEFORCOMPLETETRANSFORMATIONOFAUSTENITETOPEARLITEFROMDIFFERENTSAMPLES，ITISPOSSIBLETONOTETHEAMOUNTOFTHETRANSFORMATIONTAKINGPLACEATANYTEMPERATURETHESEPOINTSARETHENPLOTTEDONAGRAPHWITHTIMEANDTEMPERATUREASTHEAXESTHROUGHTHESEPOINTS，TRANSFORMATIONCURVESCANBEPLOTTEDASSHOWNINFIG1FOREUTECTOIDSTEELTHECURVEATEXTREMELEFTREPRESENTSTHETIMEREQUIREDFORTHETRANSFORMATIONOFAUSTENITETOPEARLITETOSTARTATANYGIVENTEMPERATURESIMILARLY，THECURVEATEXTREMERIGHTREPRESENTSTHETIMEREQUIREDFORCOMPLETINGTHETRANSFORMATIONBETWEENTHETWOCURVESARETHEPOINTSREPRESENTINGPARTIALTRANSFORMATIONTHEHORIZONTALLINESMSANDMFREPRESENTTHESTARTANDFINISHOFMARTENSITICTRANSFORMATIONCLASSIFICATIONOFHEATTREATINGPROCESSESINSOMEINSTANCES，HEATTREATMENTPROCEDURESARECLEARCUTINTERMSOFTECHNIQUEANDAPPLICATIONWHEREASINOTHERINSTANCES，DESCRIPTIONSORSIMPLEEXPLANATIONSAREINSUFFICIENTBECAUSETHESAMETECHNIQUEFREQUENTLYMAYBEUSEDTOOBTAINDIFFERENTOBJECTIVESFOREXAMPLE,STRESSRELIEVINGANDTEMPERINGAREOFTENACCOMPLISHEDWITHTHESAMEEQUIPMENTANDBYUSEOFIDENTICALTIMEANDTEMPERATURECYCLESTHEOBJECTIVES，HOWEVER，AREDIFFERENTFORTHETWOPROCESSESTHEFOLLOWINGDESCRIPTIONSOFTHEPRINCIPALHEATTREATINGPROCESSESAREGENERALLYARRANGEDACCORDINGTOTHEIRINTERRELATIONSHIPSNORMALIZINGCONSISTSOFHEATINGAFERROUSALLOYTOASUITABLETEMPERATUREUSUALLY50FTO100FOR28TO56ABOVEITSSPECIFICUPPERTRANSFORMATIONTEMPERATURETHISISFOLLOWEDBYCOOLINGINSTILLAIRTOATLEASTSOMETEMPERATUREWELLBELOWITSTRANSFORMATIONTEMPERATURERANGEFORLOWCARBONSTEELS,THERESULTINGSTRUCTUREANDPROPERTIESARETHESAMEASTHOSEACHIEVEDBYFULLANNEALING；FORMOSTFERROUSALLOYS,NORMALIZINGANDANNEALINGARENOTSYNONYMOUSNORMALIZINGUSUALLYISUSEDASACONDITIONINGTREATMENT,NOTABLYFORREFININGTHEGRAINSOFSTEELSTHATHAVEBEENSUBJECTEDTOHIGHTEMPERATURESFORFORGINGOROTHERHOTWORKINGOPERATIONSTHENORMALIZINGPROCESSUSUALLYISSUCCEEDEDBYANOTHERHEATTREATINGOPERATIONSUCHASAUSTENITIZINGFORHARDENING,ANNEALING,ORTEMPERINGANNEALINGISAGENERICTERMDENOTINGAHEATTREATMENTTHATCONSISTSOFHEATINGTOANDHOLDINGATASUITABLETEMPERATUREFOLLOWEDBYCOOLINGATASUITABLERATEITISUSEDPRIMARILYTOSOFTENMETALLICMATERIALS,BUTALSOTOSIMULTANEOUSLYPRODUCEDESIREDCHANGESINOTHERPROPERTIESORINMICROSTRUCTURETHEPURPOSEOFSUCHCHANGESMAYBE,BUTISNOTCONFINEDTO,IMPROVEMENTOFMACHINABILITY,FACILITATIONOFCOLDWORKKNOWNASINPROCESSANNEALING,IMPROVEMENTOFMECHANICALORELECTRICALPROPERTIES,ORTOINCREASEDIMENSIONALSTABILITYWHENAPPLIEDSOLELYTORELIVESTRESSES,ITCOMMONLYISCALLEDSTRESSRELIEFANNEALING,SYNONYMOUSWITHSTRESSRELIEVINGWHENTHETERM“ANNEALING”ISAPPLIEDTOFERROUSALLOYSWITHOUTQUALIFICATION,FULLANNEALINGISAPPLIEDTHISISACHIEVEDBYHEATINGABOVETHEALLOYSTRANSFORMATIONTEMPERATURE,THENAPPLYINGACOOLINGCYCLEWHICHPROVIDESMAXIMUMSOFTNESSTHISCYCLEMAYVARYWIDELY,DEPENDINGONCOMPOSITIONANDCHARACTERISTICSOFTHESPECIFICALLOYQUENCHINGISARAPIDCOOLINGOFASTEELORALLOYFROMTHEAUSTENITIZINGTEMPERATUREBYIMMERSINGTHEWORKPIECEINALIQUIDORGASEOUSMEDIUMQUENCHINGMEDIUMCOMMONLYUSEDINCLUDEWATER,5BRINE,5CAUSTICINANAQUEOUSSOLUTION,OIL,POLYMERSOLUTIONS,ORGASUSUALLYAIRORNITROGENSELECTIONOFAQUENCHINGMEDIUMDEPENDSLARGELYONTHEHARDENABILITYOFMATERIALANDTHEMASSOFTHEMATERIALBEINGTREATINGPRINCIPALLYSECTIONTHICKNESSTHECOOLINGCAPABILITIESOFTHEABOVELISTEDQUENCHINGMEDIAVARYGREATLYINSELECTINGAQUENCHINGMEDIUM,ITISBESTTOAVOIDASOLUTIONTHATHASMORECOOLINGPOWERTHANISNEEDEDTOACHIEVETHERESULTS,THUSMINIMIZINGTHEPOSSIBILITYOFCRACKINGANDWARPOFTHEPARTSBEINGTREATEDMODIFICATIONSOFTHETERMQUENCHINGINCLUDEDIRECTQUENCHING,FOGQUENCHING,HOTQUENCHING,INTERRUPTEDQUENCHING,SELECTIVEQUENCHING,SPRAYQUENCHING,ANDTIMEQUENCHINGTEMPERINGINHEATTREATINGOFFERROUSALLOYS,TEMPERINGCONSISTSOFREHEATINGTHEAUSTENITIZEDANDQUENCHHARDENEDSTEELORIRONTOSOMEPRESELECTEDTEMPERATURETHATISBELOWTHELOWERTRANSFORMATIONTEMPERATUREGENERALLYBELOW1300OR705TEMPERINGOFFERSAMEANSOFOBTAININGVARIOUSCOMBINATIONSOFMECHANICALPROPERTIESTEMPERINGTEMPERATURESUSEDFORHARDENEDSTEELSAREOFTENNOHIGHERTHAN300OF150THETERM“TEMPERING”SHOULDNOTBECONFUSEDWITHEITHERPROCESSANNEALINGORSTRESSRELIEVINGEVENTHOUGHTIMEANDTEMPERATURECYCLESFORTHETHREEPROCESSESMAYBETHESAME,THECONDITIONSOFTHEMATERIALSBEINGPROCESSEDANDTHEOBJECTIVESMAYBEDIFFERENTSTRESSRELIEVINGLIKETEMPERING,STRESSRELIEVINGISALWAYSDONEBYHEATINGTOSOMETEMPERATUREBELOWTHELOWERTRANSFORMATIONTEMPERATUREFORSTEELSANDIRONSFORNONFERROUSMETALS,THETEMPERATUREMAYVARYFROMSLIGHTLYABOVEROOMTEMPERATURETOSEVERALHUNDREDDEGREES,DEPENDINGONTHEALLOYANDTHEAMOUNTOFSTRESSRELIEFTHATISDESIREDTHEPRIMARYPURPOSEOFSTRESSRELIEVINGISTORELIEVESTRESSESTHATHAVEBEENIMPARTEDTOTHEWORKPIECEFROMSUCHPROCESSESASFORMING,ROLLING,MACHININGORWELDINGTHEUSUALPROCEDUREISTOHEATWORKPIECETOTHEPREEST