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UnitOneTheDie&MoldMaterialsandHeatTreatment模具与数控专业英语1.2Die&MoldMaterials模具与数控专业英语1.2.1CarbonSteelsCarbonsteelsareusedextensivelyindieandmoldparts．Carbonsteelsarethosesteelswhichonlycontainironandcarbon，andsmallamountsofotheralloyingelements．Carbonsteelsarethemostcommonandleastexpensivetypeofsteelusedfordiesandmolds．Thethreeprincipaltypesofcarbonsteelsusedfordieandmoldpartsarelowcarbon，mediumcarbon，andhighcarbonsteels．Lowcarbonsteelcontainsbetween0.05%and0.3%carbon．Mediumcarbonsteelcontainsbetween0.3%and0.7%carbon．Andhighcarbonsteelcontainsbetween0.7%and1.5%carbon．模具与数控专业英语Asthecarboncontentisincreasedincarbonsteel，thestrength，toughness，andhardnessalsoincreasewhenthemetalisheattreated．Theon-boardcomputer,ontheotherhand,is“soft”wired.Thus,themachinefunctionsareencodedintothecomputeratthetimeofmanufacture.TheywillnotbeerasedwhentheCNCmachineisturnedoff．Lowcarbonsteelsaresoft，toughsteelsthatareeasilymachinedandwelded．Duetotheirlowcarboncontent，thesesteelscannotbehardenedexceptbycasehardening．模具与数控专业英语Lowcarbonsteelsarewellsuitedforthefe11owingapplications：unimportantdieandmoldparts，upperandlowershoes，andsimilarsituationswherestrengthandwearresistancearenotrequired．Mediumcarbonsteelsareusedwheregreaterstrengthandtoughnessisrequired．Sincemediumcarbonsteelshaveahighercarboncontenttheycanbeheattreatedtomakepartssuchasstuds，plus，axles，andnuts．Steelsinthisgrouparemoreexpensiveaswellasmoredifficulttomachineandweldthanlowcarbonsteels．模具与数控专业英语Highcarbonsteelsarethemosthardenabletypeofcarbonsteelandareusedfrequentlyforpartswherewearresistanceisanimportantfactor．Otherapplicationswherehighcarbonsteelsarewellsuitedincludeguidepinbushings,guidepins,punch，andwearpads．Sincethecarboncontentofthesesteelsissohigh，partsmadefromhighcarbonsteelarenormallydifficulttomachineandweld．模具与数控专业英语1.2.2AlloySteelsAlloysteelsarebasicallycarbonsteelswithadditionalelementsaddedtoalterthecharacteristicsandbringaboutapredictablechangeinthemechanicalpropertiesofthealloyedmetal．Thealloyingelementsusedmostofteninsteelsaremanganese，nickel，molybdenumandchromium.Theycanhavethegeneralnameofmanganesesteel,nickelsteel,molybdenumsteelandchromiumsteelaccordingastheirspecificcontentofthealloyingelementsinalloysteels.模具与数控专业英语Althoughalloysteelscontainelementssuchaschromium，molybdenumandvanadium，twoconstituentsareessentialforheattreatment：iron，termedferriteinmetallography，andcarbon，whichcombineswithirontoformcementite，thehardintermetalliccompoundFe3C．Thesetwoconstituentsfromaeutectoidstructureknownaspearlitewhenthesteeliscooledslowlyenoughtoreachequilibrium，butbyrapidcoolingthesteelishardened．模具与数控专业英语Whensuchaquenchedsteelistempered，Structureswithmechanicalpropertiesintermediatebetweenthoseoftheslowlycooledandthequenchedconditionsareformed．Inrecentyeartherehasbeenagreaterunderstandingofthecomplexstructuralchangestakingplaceduringheattreatment,withthehelpofphasetransformationdiagrams．Useofthesediagramscanleadtobettercontroloftheheattreatmentcyclewhichinturnwillensureoptimumpropertiesandmaximumdielifeareachieved．模具与数控专业英语Stainlesssteelisatermusedtodescribehighchromiumandnickel－chromiumsteels.Thesesteelsareusedformoldswhichmustresisthightemperaturesandcorrosiveatmospheres．Somehighchromiumsteelscanbehardenedbyheattreatmentandareusedwhereresistancetowear,abrasion，andcorrosionarerequired．Typicalapplicationswhereahardenablestainlesssteelissometimespreferredareplasticinjectionmolds．Herethehighchromiumcontentallowsthesteeltobehighlypolishedandpreventsdeteriorationofthecavityfromheatandcorrosion．模具与数控专业英语1.2.3DieandMoldSteelsTheSpecificmaterialselectedforaparticulardiesormoldisnormallydeterminedbythemechanicalpropertiesnecessaryfortheproperoperationofthediesandmolds．Thesematerialsshouldbeselectedonlyafteracarefulstudyandevaluationofthefunctionandrequirementsoftheproposedtool．Inmostapplications，morethanonetypeofmaterialwillbesatisfactory，andafinalchoicewillnormallybegovernedbyrequirementsfromcustomersfordiesandmolds,suchasperformanceandeconomicconsiderationsfordiesandmolds.模具与数控专业英语Theprincipalmaterialsusedfordiesandmoldscanbedividedintothreemajorcategories：coldworktool(die)steelandhotworktool(mold)steel．Forexamples,carbidesteel,alloytoolsteel,carbontoolsteel,high-speedsteel,highalloysteel,highcarbonsteel,lowcarbonsteel,shockresistancetoolsteelandsoon．Toproperlyselectadieormoldmaterial，thereareseveralphysicalandmechanicalpropertiesyoushouldunderstandtodeterminehowthematerialsyouselectwillaffectthefunctionandperformanceofthedieormold［1］.模具与数控专业英语Physicalandmechanicalpropertiesarethosecharacteristicsofamaterialwhichcontrolhowthematerialwillreactundercertainconditions．Physicalpropertiesarethosepropertieswhicharenaturalinthematerialandcannotbepermanentlyalteredwithoutchangingthematerialitself.Thesepropertiesinclude：weight，thermalandelectricalconductivity，rateofthermalexpansion，andmeltingpoint．Themechanicalpropertiesofamaterialarethosepropertieswhichcanbepermanentlyalteredbythermalormechanicaltreatment．模具与数控专业英语Thesepropertiesincludestrength，hardness，wearresistance，toughne