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《机电专业英语 教学课件 作者 姚永玉 常云朋 周丽丹 20186-Part1-Material and Heat Treatment.ppt》由会员上传分享，免费在线阅读，更多相关内容在应用文档-天天文库。
1、Part1MaterialandHeatTreatmentUnit1MetalsUnit2HeatTreatmentUnit3Iron-CarbonEquilibriumDiagramReadingTargetUnit1MetalsReadingTarget1．Introducethecategoriesofmetalsandhowtodistinguishthem.2．Makeyouknowwhatmechanicalpropertiesmetalshaveandthedefinitionabouteachproperty.TextAs
2、wehaveseen,ferrousmetalsarealloysofironwithcarbon,thesealloysmaycontainalsosomeotherelementssuchassilicon(Si),phosphorus(P),etc.,butcarbonisthemostimportantofallelementspresentinferrousalloys[1].Ferrousmetalsareusedinindustryintwogeneralforms:castironandsteel.Thesetwoferr
3、ousalloysareusuallyproducedfrompigiron,andtheyhavedifferentcarboncontent.Steelisironcontainingfrom0.0218to2.11percentcarbon,whilecastironisanalloyofironandcarbonwiththecarboncontentmorethan2.11percent[2].Pureironisnotusedinindustrybecauseitistoosoft.Steelisanalloyofironan
4、dcarbonwithotherelementsaddedtoproducespecificproperties[3].Thevarioustypesofsteelcanbegroupedundertwomajorheadings:（1）Carbonsteel.Steelinwhichthemainalloyingelementiscarbon.Carbonsteelsarefurtherdividedintothreegroups.a．Lowcarbonsteel.Thissteelhasacarboncontentoflessthan
5、0.30percent.Itisthemostcommontypeandisoftencalledmildsteel.Itisrelativelyinexpensive,ductile,soft,andiseasilymachinedandforged.Mildsteelcannotbeheat-treated(hardened).Lowcarbonsteelisageneralpurposesteel.b．Mediumcarbonsteel.Thissteelhasacarboncontentbetween0.30percentand0
6、.80percent.Harderandstrongerthanmildsteel,itcanbehardenedbyheattreating.Mediumcarbonsteelismostcommonlyusedforforgings,castings,andmachinedpartsforautomobiles,agriculturalequipment,machines,andaircraft.c．Highcarbonsteel.Thistypeofsteeliseasilyheat-treatedtoproduceastrong,
7、toughpart.Thematerialhasacarboncontentabove0.80percent.Itfindswideuseinhandtools,cuttingtools,springs,andpianowire.（2）Highalloysteel.Thesesteelscontainsignificantamountsofotherelementsinadditiontocarbon.Thecommonhighalloysteelsare:a．Stainlesssteelwhichisproducedbyusingchr
8、omiumasasignificantalloyingelementalongwithnickelandothermetals.Theresultisatough,hard,corrosion
