精品课程铁碳相图

1,FundamentalsofMaterialsScience,郭福教授北京工业大学材料科学与工程学院,CollegeofMaterialsScienceandEngineering,材料科学基础,2,3,4,WarmingUp,Whatisconsideredasaneutecticreaction?Whatisconsideredasaneutectoidreaction?Whatisconsideredasaperitecticreaction?,L+,共晶反应,+,共析反应,L+,包晶反应,Fe-Fe3CPHASEDIAGRAM,铁碳相图,6,IMPORTANCEOFFe-Fe3CSYSTEM,Ofallbinaryalloysystems,theonethatispossiblythemostimportantisthatforironandcarbon.Bothsteelsandcastirons,primarystructuralmaterialsineverytechnologicallyadvancedculture,areessentiallyiron-carbonalloys.钢铁是现代机械制造业中应用最为广泛的金属材料。Thefocusofthislectureistostudythephasediagramforthissystemandthedevelopmentofmicrostructures.铁碳系统及其显微组织的演变Therelationshipsbetweenheattreatment,microstructure,andmechanicalpropertiesarebasedonthephasediagramofthissystem.,7,材料科学基础什么知识最重要?,您要找的是不是:铁碳相图,铁碳合金相图是研究铁碳合金的基础。它是研究铁碳合金的成分、温度和组织结构之间关系的图形。铁碳合金相图是人类经过长期实践并进行大量科学实验总结出来的。,LetsseehowTalkingTomsays,10,Fe-Fe3CPHASEDIAGRAM,Intheirsimplestform,steelsarealloysofIron(Fe)andCarbon(C).,11,Fe-Fe3CPHASEDIAGRAM,TheFe-Cphasediagramisafairlycomplexone,12,Fe-Fe3CPHASEDIAGRAM,Wewillonlyconsiderthesteelandcastironpartofthediagram,uptoaround7%Carbon.,13,14,15,WHATDOYOUKNOWABOUTIRON?,奥氏体,16,WHATDOYOUKNOWABOUTIRON?,-austenite奥氏体-solidsolutionofCinFCCFeThemaximumsolubilityofCis2.14wt%.TransformstoBCCd-ferriteat1394oCIsnotstablebelowtheeutectoidtemperature(727oC)unlesscooledrapidly,17,WHATDOYOUKNOWABOUTIRON?,d-ferrited-铁素体-solidsolutionofCinBCCFeThesamestructureasa-ferriteStableonlyathighT,above1394oCMeltsat1538oC,18,WHATDOYOUKNOWABOUTIRON?,Fe3C-ironcarbideorcementiteThisintermetalliccompoundismetastable,itremainsasacompoundindefinitelyatroomT,butdecomposes(veryslowly,withinseveralyears)intoa-FeandC(graphite)at650-700oC,渗碳体,19,AFEWCOMMENTSABOUTFe-Fe3C,CisaninterstitialimpurityinFe.Itformsasolidsolutionwitha,g,dphasesofiron.MaximumsolubilityinBCCa-ferriteislimited(max.0.022wt%at727oC)-BCChasrelativelysmallinterstitialpositions.,MaximumsolubilityinFCCausteniteis2.14wt%at1147oC-FCChaslargerinterstitialpositions,20,MECHANICALPROPERTIES,Cementiteisveryhardandbrittle-canstrengthensteels.Mechanicalpropertiesalsodependonthemicrostructure,thatis,howferriteandcementitearemixed.,21,MAGNETICPROPERTIES,a-ferriteismagneticbelow768oC.Austeniteisnon-magnetic.,22,CLASSIFICATIONOFFERROUSALLOYS,铁碳合金的分类,23,CLASSIFICATIONOFFERROUSALLOYS,24,CLASSIFICATIONOFFERROUSALLOYS,EutectoidSteel(C=0.76%),共析钢,25,CLASSIFICATIONOFFERROUSALLOYS,HypoeutectoidSteel(C0.76%),过共析钢,27,CLASSIFICATIONOFFERROUSALLOYS,EutecticCastIron(C=4.3%),共晶白口铸铁,28,CLASSIFICATIONOFFERROUSALLOYS,HypoeutecticCastIron(C4.3%),过共晶白口铸铁,30,IMPORTANTLINESANDREACTIONS,重要的线及反应,31,IMPORTANTLINESANDREACTIONS,32,A,B,C,D,Liquidusline,H,J,E,F,Solidusline,A,C,33,A,B,C,D,H,J,E,F,A,C,Ledeburite,莱氏体,34,A,B,C,D,H,J,E,F,A,C,Pearlite,珠光体,S,P,k,35,A,B,C,D,H,J,E,F,A,C,Peritectic:0.17wt%C,1493oCL+,L+,Austenite,36,A,B,C,D,Liquidusline,H,J,E,F,Solidusline,A,C,S,Solvusline,solubilitylimitofCin.,Fe3CII,proeutectoidFe3C,二次渗碳体，由奥氏体中析出，常呈网状分布于奥氏体的晶界,P,Solvusline,solubilitylimitofCin.,Fe3CIII,三次渗碳体，沿铁素体晶界，较少，略,Acm,A3,G,Q,37,EQUILIBRIUMMICROSTRUCTURE,平衡显微组织,38,EQUILIBRIUMMICROSTRUCTURE,1,2,3,4,5,6,39,1EUTECTOID(共析成分),Whenalloyofeutectoidcomposition(0.76wt%C)iscooledslowlyitformspearlite,alamellarorlayeredstructureoftwophases:-ferriteandcementite(Fe3C),40,1EUTECTOID(共析成分),共析钢结晶过程1-22-33-4,41,Pearlite(珠光体),Thepearliteexistsasgrains,oftentermed“colonies”;withineachcolonythelayersareorientedinthesamedirection,whichvariesfromonecolonytoanother.片层方向大致相同的区域,ferrite,Colony(珠光体团),cementite,42,Pearlite(珠光体),100,200,500,43,Pearlite(珠光体),Thelayersofalternatingphasesinpearliteareformedforthesamereasonaslayeredstructureofeutecticstructures:redistributionCatomsbetweenferrite(0.022wt%)andcementite(6.7wt%)byatomicdiffusion.扩散，C的再分配,Mechanically,pearlitehaspropertiesintermediatetosoft,ductileferriteandhard,brittlecementite.,44,2HYPOEUTECTOID(亚共析成分),In+region,thecompositionofphasechangesalongGP,thecompositionofphasechangesalongGS,g,a+g,a+Fe3C,先共析铁素体,G,S,P,45,2HYPOEUTECTOID(亚共析成分),亚共析钢结晶过程,a+g,a+Fe3C,g,46,2HYPOEUTECTOID(亚共析成分),08钢,20钢,45钢,65钢,47,2HYPOEUTECTOID(亚共析成分),Hypoeutectoidalloyscontainproeutectoidferrite(formedabovetheeutectoidtemperature)plustheeutectoidpearlitethatcontaineutectoidferriteandcementite.,Microstructureofa0.38wt%steel.CourtesyRepublicSteelCorp.,48,3HYPEREUTECTOID(过共析成分),g,g+Fe3C,a+Fe3C,二次渗碳体,In+Fe3Cregion,thecompositionofcementitephaseremainsconstant,thecompositionofphasechangesalongES,S,E,49,3HYPEREUTECTOID(过共析成分),过共析钢结晶过程,g,g+Fe3C,a+Fe3C,50,3HYPEREUTECTOID(过共析成分),T12,100,200,500,51,3HYPEREUTECTOID(过共析成分),Hypereutectoidalloyscontainproeutectoidcementite(formedabovetheeutectoidtemperature)pluspearlitethatcontaineutectoidferriteandcementite.,Microstructureofa1.4wt%steel.CourtesyU.S.SteelCorp.,52,CALCULATIONOFPHASEAMOUNT,Applicationoftheleverrulewithtielinethatextendsfromtheeutectoidcomposition(0.76wt%C)to(+Fe3C)boundary(0.022wt%C)forhypoeutectoidalloysandto(+Fe3C)Fe3Cboundary(6.7wt%C)forhypereutectoidalloys.,Fractionofpearlite:,Fractionofproeutectoid:,53,CALCULATIONOFPHASEAMOUNT,Applicationoftheleverrulewithtielinethatextendsfromtheeutectoidcomposition(0.76wt%C)to(+Fe3C)boundary(0.022wt%C)forhypoeutectoidalloysandto(+Fe3C)Fe3Cboundary(6.7wt%C)forhypereutectoidalloys.,Fractionofpearlite:,Fractionofproeutectoidcementite:,54,4EUTECTIC(共晶成分),L,+Fe3C,共晶渗碳体,Fe3CII,二次渗碳体,P+Fe3CII+Fe3C,莱氏体Ld,变态莱氏体Ld,55,4EUTECTIC(共晶成分),L,+Fe3C,P+Fe3CII+Fe3C,56,4EUTECTIC(共晶成分),共晶白口铸铁室温平衡组织,57,5HYPOEUTECTIC(亚共晶成分),L,I+Ld(+Fe3C),先共晶奥氏体,Fe3CII,二次渗碳体,I+L,莱氏体,由I析出,由析出,P,P,Fe3C,Fe3CII,Fe3CII,Fe3C,+,+,Ld(,+,+,),Fe3CII,Fe3CII,58,5HYPOEUTECTIC(亚共晶成分),L+,Ld+Fe3CII+,P+Fe3CII+Ld,L,59,5HYPOEUTECTIC(亚共晶成分),亚共晶白口铸铁室温平衡组织,60,6HYPEREUTECTIC(过共晶成分),L,Ld(+Fe3C),一次渗碳体,Fe3CII,二次渗碳体,L+Fe3CI,莱氏体,Fe3CII,P,Fe3C,Ld(,+,),Fe3CII,Fe3CII,+Fe3CI,+Fe3CI,+,61,6HYPEREUTECTIC(过共晶成分),L+Fe3CI,Ld+Fe3CI,L,Ld+Fe3CI,62,6HYPEREUTECTIC(过共晶成分),过共晶白口铸铁室温平衡组织,63,BRIEFSUMMARY,“一二三四五”巧记铁碳相图,64,一种化合物渗碳体具有复杂结构的间隙化合物从金属液态直接结晶出的渗碳体称为一次渗碳体（Fe3CI）从奥氏体中析出的渗碳体称为二次渗碳体（Fe3CII）从铁素体中析出的渗碳体称为三次渗碳体（Fe3CIII）不发生同素异构转变，硬度高，塑性很差。,“一二三四五”巧记铁碳相图,65,二个重要温度1147、727（其他温度是否知道？912，1227，1495，1538）,Fe,Fe3C,A,C,D,E,F,G,S,P,K,B,H,J,N,1147,727,“一二三四五”巧记铁碳相图,66,三个重要转变包晶转变反应式共晶转变反应式共析转变反应式,Fe,Fe3C,A,C,D,E,F,G,S,P,K,B,H,J,N,“一二三四五”巧记铁碳相图,67,四条重要的线PSK、ES、GS、PQ,Fe,Fe3C,A,C,D,E,F,G,S,P,K,B,H,J,N,“一二三四五”巧记铁碳相图,Q,68,“一二三四五”巧记铁碳相图,五个重要的成份