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1、Unit11.2FerrousMetalsandAlloysByvirtueoftheirwiderangeofmechanical,physical,andchemicalproperties,ferrousmetalsandalloysareamongthemostusefulofallmetals.Ferrousmetalsandalloyscontainironastheirbasemetal:thegeneralcategoriesarecastirons,carbonandalloysteels,stainlesssteels,too
2、landdiesteels.1.2黑色金属及其合金：由于它们的一系列广泛的机械物理和化学的特征，黑色金属及其合金是所有金属中最有用的铁是黑色金属及其合金中的基本元素主要种类有铸铁，碳钢，合金钢，不锈钢，工具钢和磨具钢Thetermcastironreferstoafamilyofferrousalloyscomposedofiron,carbon(rangingfrom2.11%toabout4.5%),andsilicon(uptoabout3.5%).Castironsareusuallyclassifiedasfollows:1.Grayc
3、astiron,orgrayiron;2.Ductilecastiron,nodularcastiron,orsphericalgraphitecastiron;3.Whitecastiron;4.Malleableiron;5.Compactedgraphiteiron。（），它包含铁碳（2.5%—4.5%）和硅（3.5%）铸铁的分类如下1.灰铸铁2.球墨铸铁3.白口铸铁4.可锻铸铁5.如墨铸铁TheequilibriumphasediagramrelevanttocastironsisshowninFig.1.1,inwhichtherigh
4、tboundaryis100%carbon,thatispuregraphite.Theeutectictemperatureis1154hC(2109hF),andsocastironsarecompletelyliquidattemperatureslowerthanthoserequiredforliquidsteels.Consequently,ironwithhighcarboncontentcanbecastatlowertemperaturesthancansteels.有关铸铁的平衡相图如图1.1所示其右边界是100%的碳那是纯石
5、墨，其共晶温度是1154℃因此铸铁可以在比那些熔化钢更低的温度下完全液化所以含碳量较高的铸铁的浇注温度比钢低。Carbonsteelsaregenerallyclassifiedbytheirproportion(byweight)ofcarboncontent.1.Low-carbonsteel,alsocalledmildsteel,haslessthan1.30%carbon.Itisgenerallyusedforcommonindustrialproducts,suchasbolts,nuts,sheet,plate,andtubes,
6、andformachinecomponentsthatdonotrequirehighstrength.3.碳钢：碳铜大体上是按碳含量的臂力来分类的1）低碳钢又叫做软钢其碳含量小于0.30%它用于普遍的工业产品，例如螺栓，螺母。钢板，港片钢管和那些强度要求不高的机器零件Unit55.1IntroductionConventionalmachiningisthegroupofmachiningoperationsthatusesingle-ormulti-pointtoolstoremovematerialintheformofchips.Meta
7、lcuttinginvolvesremovingmetalthroughmachiningoperations.Machiningtraditionallytakesplaceonlathes,drillpresses,andmillingmachineswiththeuseofvariouscuttingtools.Mostmachininghasverylowset-upcostcomparedwithforming,molding,andcastingprocesses.However,machiningismuchmoreexpensiv
8、eforhighvolumes.Machiningisnecessarywheretighttolerancesondimensions
