精品课程铁碳相图PPT文件格式下载.ppt

1、What is considered as a peritectic reaction?,L+,共晶反应,+,共析反应,L+,包晶反应,Fe-Fe3C PHASE DIAGRAM,铁碳相图,6,IMPORTANCE OF Fe-Fe3C SYSTEM,Of all binary alloy systems,the one that is possibly the most important is that for iron and carbon.Both steels and cast irons,primary structural materials in every technolog

2、ically advanced culture,are essentially iron-carbon alloys.钢铁是现代机械制造业中应用最为广泛的金属材料。The focus of this lecture is to study the phase diagram for this system and the development of microstructures.铁碳系统及其显微组织的演变The relationships between heat treatment,microstructure,and mechanical properties are based on

3、 the phase diagram of this system.,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。,Lets see how Talking Tom says,10,Fe-Fe3C PHASE DIAGRAM,In their simplest form,steels are alloys of Iron（Fe）and Carbon（C）.,11,Fe-Fe3C PHASE DIAGRAM,The Fe-C phas

4、e diagram is a fairly complex one,12,Fe-Fe3C PHASE DIAGRAM,We will only consider the steel and cast iron part of the diagram,up to around 7%Carbon.,13,14,15,WHAT DO YOU KNOW ABOUT IRON?,奥氏体,16,WHAT DO YOU KNOW ABOUT IRON?,-austenite奥氏体-solid solution of C in FCC FeThe maximum solubility of C is 2.14

5、 wt%.Transforms to BCC d-ferrite at 1394oCIs not stable below the eutectoid temperature（727oC）unless cooled rapidly,17,WHAT DO YOU KNOW ABOUT IRON?,d-ferrited-铁素体-solid solution of C in BCC Fe The same structure as a-ferrite Stable only at high T,above 1394oC Melts at 1538oC,18,WHAT DO YOU KNOW ABOU

6、T IRON?,Fe3C-iron carbide or cementite This intermetallic compound is metastable,it remains as a compound indefinitely at room T,but decomposes（very slowly,within several years）into a-Fe and C（graphite）at 650-700oC,渗碳体,19,A FEW COMMENTS ABOUT Fe-Fe3C,C is an interstitial impurity in Fe.It forms a so

7、lid solution with a,g,d phases of iron.Maximum solubility in BCC a-ferrite is limited（max.0.022 wt%at 727oC）-BCC has relatively small interstitial positions.,Maximum solubility in FCC austenite is 2.14 wt%at 1147oC-FCC has larger interstitial positions,20,MECHANICAL PROPERTIES,Cementite is very hard

8、 and brittle-can strengthen steels.Mechanical properties also depend on the microstructure,that is,how ferrite and cementite are mixed.,21,MAGNETIC PROPERTIES,a-ferrite is magnetic below 768oC.Austenite is non-magnetic.,22,CLASSIFICATION OF FERROUS ALLOYS,铁碳合金的分类,23,CLASSIFICATION OF FERROUS ALLOYS,

9、24,CLASSIFICATION OF FERROUS ALLOYS,Eutectoid Steel（C=0.76%）,共析钢,25,CLASSIFICATION OF FERROUS ALLOYS,Hypoeutectoid Steel（C0.76%）,亚共析钢,26,CLASSIFICATION OF FERROUS ALLOYS,Hypereutectoid Steel（C0.76%）,过共析钢,27,CLASSIFICATION OF FERROUS ALLOYS,Eutectic Cast Iron（C=4.3%）,共晶白口铸铁,28,CLASSIFICATION OF FERRO

10、US ALLOYS,Hypoeutectic Cast Iron（C4.3%）,亚共晶白口铸铁,29,CLASSIFICATION OF FERROUS ALLOYS,Hypereutectic Cast Iron（C4.3%）,过共晶白口铸铁,30,IMPORTANT LINES AND REACTIONS,重要的线及反应,31,IMPORTANT LINES AND REACTIONS,32,A,B,C,D,Liquidus line,H,J,E,F,Solidus line,A,C,33,A,B,C,D,H,J,E,F,A,C,Ledeburite,莱氏体,34,A,B,C,D,H,J,

11、E,F,A,C,Pearlite,珠光体,S,P,k,35,A,B,C,D,H,J,E,F,A,C,Peritectic:0.17 wt%C,1493oCL+,L+,Austenite,36,A,B,C,D,Liquidus line,H,J,E,F,Solidus line,A,C,S,Solvus line,solubility limit of C in.,Fe3CII,proeutectoid Fe3C,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,Solvus line,solubility limit of C in.,Fe3CIII,三次渗碳体，沿铁素体晶界，较少，

12、略,Acm,A3,G,Q,37,EQUILIBRIUM MICROSTRUCTURE,平衡显微组织,38,EQUILIBRIUM MICROSTRUCTURE,1,2,3,4,5,6,39,1 EUTECTOID（共析成分）,When alloy of eutectoid composition（0.76 wt%C）is cooled slowly it forms pearlite,a lamellar or layered structure of two phases:-ferrite and cementite（Fe3C）,40,1 EUTECTOID（共析成分）,共析钢结晶过程1-2

13、2-33-4,41,Pearlite（珠光体）,The pearlite exists as grains,often termed“colonies”;within each colony the layers are oriented in the same direction,which varies from one colony to another.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）,The layers of alternating pha

14、ses in pearlite are formed for the same reason as layered structure of eutectic structures:redistribution C atoms between ferrite（0.022 wt%）and cementite（6.7 wt%）by atomic diffusion.扩散，C的再分配,Mechanically,pearlite has properties intermediate to soft,ductile ferrite and hard,brittle cementite.,44,2 HY

15、POEUTECTOID（亚共析成分）,In+region,the composition of phase changes along GP,the composition of phase changes along GS,g,a+g,a+Fe3C,先共析铁素体,G,S,P,45,2 HYPOEUTECTOID（亚共析成分）,亚共析钢结晶过程,a+g,a+Fe3C,g,46,2 HYPOEUTECTOID（亚共析成分）,08钢,20钢,45钢,65钢,47,2 HYPOEUTECTOID（亚共析成分）,Hypoeutectoid alloys contain proeutectoid fer

16、rite（formed above the eutectoid temperature）plus the eutectoid pearlite that contain eutectoid ferrite and cementite.,Microstructure of a 0.38wt%steel.Courtesy Republic Steel Corp.,48,3 HYPEREUTECTOID（过共析成分）,g,g+Fe3C,a+Fe3C,二次渗碳体,In+Fe3C region,the composition of cementite phase remains constant,the

17、 composition of phase changes along ES,S,E,49,3 HYPEREUTECTOID（过共析成分）,过共析钢结晶过程,g,g+Fe3C,a+Fe3C,50,3 HYPEREUTECTOID（过共析成分）,T12,100,200,500,51,3 HYPEREUTECTOID（过共析成分）,Hypereutectoid alloys contain proeutectoid cementite（formed above the eutectoid temperature）plus pearlite that contain eutectoid ferrit

18、e and cementite.,Microstructure of a 1.4wt%steel.Courtesy U.S.Steel Corp.,52,CALCULATION OF PHASE AMOUNT,Application of the lever rule with tie line that extends from the eutectoid composition（0.76 wt%C）to（+Fe3C）boundary（0.022 wt%C）for hypoeutectoid alloys and to（+Fe3C）Fe3C boundary（6.7 wt%C）for hyp

19、ereutectoid alloys.,Fraction of pearlite:,Fraction of proeutectoid:,53,CALCULATION OF PHASE AMOUNT,Application of the lever rule with tie line that extends from the eutectoid composition（0.76 wt%C）to（+Fe3C）boundary（0.022 wt%C）for hypoeutectoid alloys and to（+Fe3C）Fe3C boundary（6.7 wt%C）for hypereute

20、ctoid alloys.,Fraction of pearlite:,Fraction of proeutectoid cementite:,54,4 EUTECTIC（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,55,4 EUTECTIC（共晶成分）,L,+Fe3C,P+Fe3CII+Fe3C,56,4 EUTECTIC（共晶成分）,共晶白口铸铁室温平衡组织,57,5 HYPOEUTECTIC（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,

21、P,Fe3C,Fe3CII,Fe3CII,Fe3C,+,+,Ld（,+,+,）,Fe3CII,Fe3CII,58,5 HYPOEUTECTIC（亚共晶成分）,L+,Ld+Fe3CII+,P+Fe3CII+Ld,L,59,5 HYPOEUTECTIC（亚共晶成分）,亚共晶白口铸铁室温平衡组织,60,6 HYPEREUTECTIC（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,+,61,6 HYPEREUTECTIC（过共晶成分）,L+Fe3CI

22、,Ld+Fe3CI,L,Ld+Fe3CI,62,6 HYPEREUTECTIC（过共晶成分）,过共晶白口铸铁室温平衡组织,63,BRIEF SUMMARY,“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,

23、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,五个重要的成份点 P、S、E、C、K,Fe,Fe3C,A,C,D,E,F,G,S,P,K,B,H,J,N,69,BRIEF SUMMARY,70,COMING UP NEXT,INFLUEN

24、CE OF ALLOYING ELEMENTSAddition of alloying elements affects the position of eutectoid with respect to temperature and to carbon concentration.The purpose of alloying:improve corrosion resistance,and/or render amenable to heat treatment.,71,HOMEWORK,HOMEWORK,阅读材料科学基础中文教材铁碳相图的章节阅读Callister教材Chapter 9

25、铁碳相图英文内容详细阅读Callister教材中的例题9.4用一周的时间完成作业15中的习题121,College of Material Science and Engineering,课后作业,72,重点习题,1分析含碳量wc分别为0.45%、1.2%的铁碳合金在极缓慢冷却时的组织转变过程，绘出室温组织示意图并在图上标明组织组成物名称2分析一次渗碳体、二次渗碳体、三次渗碳体、共晶渗碳体、共析渗碳体的异同之处,73,重点习题,3根据Fe-Fe3C相图计算：室温下，wc 0.2%的钢中珠光体和铁素体相对量 室温下，wc为1.2%的钢中珠光体和二次渗碳体的相对量 727共析反应刚完成时，珠光体中铁素体和渗碳体的相对量 wc为1.2%的钢在1400、1100和800时奥氏体中的含碳量,Thank You!,