先共析渗碳体上形核的珠光体晶体学研究
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摘要
利用SEM和EBSD技术表征了Fe-1.29C-13.9Mn (质量分数,%)钢中先共析渗碳体上形核珠光体的形貌和晶体学。大多数珠光体内铁素体与奥氏体之间接近K-S位向关系,与渗碳体之间则可出现多种择优位向关系。分析表明,魏氏渗碳体旁珠光体的形核领先相是铁素体,未观察到珠光体中渗碳体从魏氏渗碳体分支生长,或它们之间存在择优取向。晶界渗碳体旁珠光体存在2种可能:晶界渗碳体可延续为珠光体的渗碳体,同时铁素体往往与背靠奥氏体接近K-S位向关系,渗碳体可视为领先相,不排除铁素体为领先相的可能;同时也观察到晶界渗碳体与珠光体内渗碳体呈现不同取向,此时领先相是铁素体。珠光体团初期形貌不规则,生长后期两相基本保持平行片层结构,同一铁素体片层会存在取向变化甚至分层。
Pearlite is common microstructure in the carbon steel, which is widely applied in the railway steel and cold drawn steel where high wear resistance and strength are required. The pearlite colony is a circumscribed aggregate within which lamellae of cementite and ferrite phases have the same orientation. A cluster of wedge-shaped pearlite colonies will form the pearlite group nodules. The morphology of pearlite colonies will be influenced by the crystallography of pearlite. The common orientation relationship(OR) between pearlitic ferrite and pearlitic cementite is the Pitsch-Petch, Bagaryatsky, and Isaichev ORs. Combined with deep etching, SEM was used to investigate the morphology and crystallography of pearlite colonies and pearlite group nodules nucleated on the proeutectoid cementite in a Fe-1.29C-13.9Mn steel. The results showed that the initial morphology of the pearlite is irregular, but the pearlite possesses a parallel lamellar structure at the later stage of growth. Mutual ORs between phases of austenite, cementite, and ferrite in pearlite, proeutectoid grain boundary cementite, and Widmannst?tten cementite were measured with the EBSD technique. Several reproducible ORs between cementite and ferrite lamellar have been observed, including the Pitsch-Petch, Bagaryatsky, and Isaichev ORs, without a particularly dominant OR. Since the two phases in the pearlite colonies have reproducible preferential OR, they are usually not independently nucleated, otherwise the independent nucleation of the cementite and ferrite inside the austenite has special crystallographic requirements for the mutual ORs between ferrite, cementite, and austenite. Thus, there will be a phase that nucleates first, which is called the "active nucleus". The active nucleus of pearlite has been carefully examined mainly according to the preferred OR between the pearlitic phases and existing phases. While the development of the pearlite crystallography is influenced by the active nucleus, no clear relationship was found between the ORs within the pearlite and active nucleus of the pearlite. The ORs between austenite and major pearlitic ferrite are near the K-S OR, but the ORs between austenite and the pearlitic cementite are various, depending on the preferred ORs between pearlitic ferrite and both austenite and pearlitic cementite. Widmannst?tten cementite has never been seen to grow into pearlite. The measured data suggests that active nucleus of the pearlite colonies and pearlite group nodules nucleated on Widmannst?tten cementite is ferrite. In some cases, grain boundary cementite was seen to grow as part of pearlite. Consequently, the grain boundary cementite is regarded as the active nucleus, though a preferred OR often coexists between pearlitic ferrite and either austenite or proeutectoid cementite. In other cases, the orientations of pearlitic cementite and grain-boundary cementite are discontinuous. For these cases, the ferrite is likely the active nucleus of pearlite. The orientation of pearlitic ferrite was seen to alter with the growth of pearlite, even causing the split of a single ferrite layer into two grain layers with a considerable misorientation. Significant distortion varying with the layers of pearlite was noticed in austenite near the pearlite growth front, indicating an evident strain field caused by the pearlite transformation. This requests a further investigation.
Pearlite is common microstructure in the carbon steel, which is widely applied in the railway steel and cold drawn steel where high wear resistance and strength are required. The pearlite colony is a circumscribed aggregate within which lamellae of cementite and ferrite phases have the same orientation. A cluster of wedge-shaped pearlite colonies will form the pearlite group nodules. The morphology of pearlite colonies will be influenced by the crystallography of pearlite. The common orientation relationship(OR) between pearlitic ferrite and pearlitic cementite is the Pitsch-Petch, Bagaryatsky, and Isaichev ORs. Combined with deep etching, SEM was used to investigate the morphology and crystallography of pearlite colonies and pearlite group nodules nucleated on the proeutectoid cementite in a Fe-1.29C-13.9Mn steel. The results showed that the initial morphology of the pearlite is irregular, but the pearlite possesses a parallel lamellar structure at the later stage of growth. Mutual ORs between phases of austenite, cementite, and ferrite in pearlite, proeutectoid grain boundary cementite, and Widmannst?tten cementite were measured with the EBSD technique. Several reproducible ORs between cementite and ferrite lamellar have been observed, including the Pitsch-Petch, Bagaryatsky, and Isaichev ORs, without a particularly dominant OR. Since the two phases in the pearlite colonies have reproducible preferential OR, they are usually not independently nucleated, otherwise the independent nucleation of the cementite and ferrite inside the austenite has special crystallographic requirements for the mutual ORs between ferrite, cementite, and austenite. Thus, there will be a phase that nucleates first, which is called the "active nucleus". The active nucleus of pearlite has been carefully examined mainly according to the preferred OR between the pearlitic phases and existing phases. While the development of the pearlite crystallography is influenced by the active nucleus, no clear relationship was found between the ORs within the pearlite and active nucleus of the pearlite. The ORs between austenite and major pearlitic ferrite are near the K-S OR, but the ORs between austenite and the pearlitic cementite are various, depending on the preferred ORs between pearlitic ferrite and both austenite and pearlitic cementite. Widmannst?tten cementite has never been seen to grow into pearlite. The measured data suggests that active nucleus of the pearlite colonies and pearlite group nodules nucleated on Widmannst?tten cementite is ferrite. In some cases, grain boundary cementite was seen to grow as part of pearlite. Consequently, the grain boundary cementite is regarded as the active nucleus, though a preferred OR often coexists between pearlitic ferrite and either austenite or proeutectoid cementite. In other cases, the orientations of pearlitic cementite and grain-boundary cementite are discontinuous. For these cases, the ferrite is likely the active nucleus of pearlite. The orientation of pearlitic ferrite was seen to alter with the growth of pearlite, even causing the split of a single ferrite layer into two grain layers with a considerable misorientation. Significant distortion varying with the layers of pearlite was noticed in austenite near the pearlite growth front, indicating an evident strain field caused by the pearlite transformation. This requests a further investigation.
引文
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[14]Petch N J.The orientation relationships between cementite andα-iron[J].Acta Crystallogr.,1953,6:96
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[18]Zhou D S,Shiflet G J.Ferrite:Cementite crystallography in pearlite[J].Metall.Trans.,1992,23A:1259
[19]Kim J,Kang K,Ryu S.Characterization of the misfit dislocations at the ferrite/cementite interface in pearlitic steel:An atomistic simulation study[J].Int.J.Plast.,2016,83:302
[20]Zhou Y T,Zheng S J,Jiang Y X,et al.Atomic structure of the Fe/Fe3C interface with the Isaichev orientation in pearlite[J].Philos.Mag.,2017,97:2375
[21]Guziewski M,Coleman S P,Weinberger C R.Atomistic investigation into the atomic structure and energetics of the ferritecementite interface:The bagaryatskii orientation[J].Acta Mater.,2016,119:184
[22]Mangan M A,Shiflet G J.The pitsch-petch orientation relationship in ferrous pearlite at small undercooling[J].Metall.Mater.Trans.,1999,30A:2767
[23]Guo Z H.Progress in the pearlitic transformation mechanism in steels[J].Trans.Meter.Heat Treat.,2003,24(3):1(郭正洪.钢中珠光体相变机制的研究进展[J].材料热处理学报,2003,24(3):1)
[24]Yu Y N.Principles of Metallography[M].2nd Ed.,Beijing:Metallurgical Industry Press,2013:839(余永宁.金属学原理[M].第2版,北京:冶金工业出版社,2013:839)
[25]Samuel F H.A crystallographic study of pearlite growth in steels[J].Trans.Iron Steel Inst.Jpn.,1983,23:403
[26]Kurdjumow G,Sachs G.über den mechanismus der stahlh?rtung[J].Z.für Phys.,1930,64:325
[27]Nishiyama Z.X-ray investigation of the mechanism of the transformation from face-centered cubic lattice to body-centered cubic[J].Sci.Rep.Tohoku Univ.,1934,23:637
[28]Wassermann G.üeber den mechanismus derα-γumwandlung des eisens[J].Mitt.K.-Wilh.-Inst.Eisenforsch,1935,17:149
[29]Pitsch W.Der orientierungszusammenhang zwischen zementit und austenit[J].Acta Metall.,1962,10:897
[30]Farooque M,Edmonds D V.The orientation relationships between Widmannst?tten cementite and austenite[A].Proceedings of the XII International Congress for Electron Microscopy[C].San Francisco:San Francisco Press,1990:910
[31]Thompson S W,Howell P R.The orientation relationship between intragranularly nucleated widmanstattin cementite and austenite in a commercial hypereutectold steel[J].Scr.Metall.,1987,21:1353
[32]Mangan M A,Kral M V,Spanos G.Correlation between the crystallography and morphology of proeutectoid Widmanst?tten cementite precipitates[J].Acta Mater.,1999,47:4263
[33]Zilnyk K D,Almeida Junior D R,Sandim H R Z,et al.Misorientation distribution between martensite and austenite in Fe-31 wt%Ni-0.01 wt%C[J].Acta Mater.,2018,143:227
[34]Bain E C.The nature of martensite[J].Trans.Am.Inst.Min.Metall.Eng.,1924,70:25
[35]Greninger A B,Troiano A R.Crystallography of austenite decomposition[J].Trans.Am.Inst.Min.Metall.Eng.,1940,140:307
[36]King A D,Bell T.Crystallography of grain boundary proeutectoid ferrite[J].Metall.Trans.,1975,6A:1419
[37]Grong?,Kluken A O,Nylund H K,et al.Catalyst effects in heterogeneous nucleation of acicular ferrite[J].Metall.Mater.Trans.,1995,26A:525
[38]Spanos G,Kral M V.The proeutectoid cementite transformation in steels[J].Int.Mater.Rev.,2009,54:19
[39]Xu W S,Zhang W Z.A new orientation relationship between cementite and austenite and coexistence of pseudo-primary and secondary dislocations in the habit plane[J].Philos.Mag.,2018,98:75
[40]Darken L S,Fisher P M.Decomposition of Austenite by Diffusional Processes[M].New York:Intersciences Publishers,1962:249
[2]Fang F,Zhao Y F,Liu P P,et al.Deformation of cementite in cold drawn pearlitic steel wire[J].Mater.Sci.Eng.,2014,A608:11
[3]Zhou L C,Hu X J,Ma C,et al.Effect of pearlitic lamella orientation on deformation of pearlite steel wire during cold drawing[J].Acta Metall.Sin.,2015,51:897(周立初,胡显军,马驰等.珠光体层片取向对冷拔珠光体钢丝形变的影响[J].金属学报,2015,51:897)
[4]Hillert M.Decomposition of Austenite by Diffusional Processes[M].New York:Interscience Publishers,1962:219
[5]Aaronson H I,Enomoto M,Lee J K.Mechanisms of Diffusional Phase Transformations in Metals and Alloys[M].Boca Raton:CRC Press,2010:576
[6]Dippenaar R J,Honeycombe R W K.The crystallography and nucleation of pearlite[J].Proc.Roy.Soc.London,1973,333A:455
[7]Walentek A,Seefeldt M,Verlinden B,et al.Electron backscatter diffraction on pearlite structures in steel[J].J.Microsc.,2006,224:256
[8]Nakada N,Koga N,Tsuchiyama T,et al.Crystallographic orientation rotation and internal stress in pearlite colony[J].Scr.Mater.,2009,61:133
[9]Guo N,Liu Q.Back-scattered electron imaging combined with EBSD technique for characterization of pearlitic steels[J].J.Microsc.,2012,246:221
[10]Durgaprasad A,Giri S,Lenka S,et al.Defining a relationship between pearlite morphology and ferrite crystallographic orientation[J].Acta Mater.,2017,129:278
[11]Samuel F H,Hussein A A.A crystallographic study of nucleation of pearlite[J].Trans.Iron Steel Inst.Jpn.,1983,23:65
[12]Bagaryatsky Y A.Veroyatnue mechanezm raspada martenseeta[J].Dokl.Akad.Nauk SSSR,1950,73:1161
[13]Isaichev I V.Orientation of cementite in tempered carbon steel[J].Zh.Tekhn.Fiz,1947,17:835
[14]Petch N J.The orientation relationships between cementite andα-iron[J].Acta Crystallogr.,1953,6:96
[15]Pitsch W.Der orientierungszusammenhang zwischen zementit und ferrit im perlit[J].Acta Metall.,1962,10:79
[16]Zhang M X,Kelly P M.Accurate orientation relationships between ferrite and cementite in pearlite[J].Scr.Mater.,1997,37:2009
[17]Zhang M X,Kelly P M.The morphology and formation mechanism of pearlite in steels[J].Mater.Charact.,2009,60:545
[18]Zhou D S,Shiflet G J.Ferrite:Cementite crystallography in pearlite[J].Metall.Trans.,1992,23A:1259
[19]Kim J,Kang K,Ryu S.Characterization of the misfit dislocations at the ferrite/cementite interface in pearlitic steel:An atomistic simulation study[J].Int.J.Plast.,2016,83:302
[20]Zhou Y T,Zheng S J,Jiang Y X,et al.Atomic structure of the Fe/Fe3C interface with the Isaichev orientation in pearlite[J].Philos.Mag.,2017,97:2375
[21]Guziewski M,Coleman S P,Weinberger C R.Atomistic investigation into the atomic structure and energetics of the ferritecementite interface:The bagaryatskii orientation[J].Acta Mater.,2016,119:184
[22]Mangan M A,Shiflet G J.The pitsch-petch orientation relationship in ferrous pearlite at small undercooling[J].Metall.Mater.Trans.,1999,30A:2767
[23]Guo Z H.Progress in the pearlitic transformation mechanism in steels[J].Trans.Meter.Heat Treat.,2003,24(3):1(郭正洪.钢中珠光体相变机制的研究进展[J].材料热处理学报,2003,24(3):1)
[24]Yu Y N.Principles of Metallography[M].2nd Ed.,Beijing:Metallurgical Industry Press,2013:839(余永宁.金属学原理[M].第2版,北京:冶金工业出版社,2013:839)
[25]Samuel F H.A crystallographic study of pearlite growth in steels[J].Trans.Iron Steel Inst.Jpn.,1983,23:403
[26]Kurdjumow G,Sachs G.über den mechanismus der stahlh?rtung[J].Z.für Phys.,1930,64:325
[27]Nishiyama Z.X-ray investigation of the mechanism of the transformation from face-centered cubic lattice to body-centered cubic[J].Sci.Rep.Tohoku Univ.,1934,23:637
[28]Wassermann G.üeber den mechanismus derα-γumwandlung des eisens[J].Mitt.K.-Wilh.-Inst.Eisenforsch,1935,17:149
[29]Pitsch W.Der orientierungszusammenhang zwischen zementit und austenit[J].Acta Metall.,1962,10:897
[30]Farooque M,Edmonds D V.The orientation relationships between Widmannst?tten cementite and austenite[A].Proceedings of the XII International Congress for Electron Microscopy[C].San Francisco:San Francisco Press,1990:910
[31]Thompson S W,Howell P R.The orientation relationship between intragranularly nucleated widmanstattin cementite and austenite in a commercial hypereutectold steel[J].Scr.Metall.,1987,21:1353
[32]Mangan M A,Kral M V,Spanos G.Correlation between the crystallography and morphology of proeutectoid Widmanst?tten cementite precipitates[J].Acta Mater.,1999,47:4263
[33]Zilnyk K D,Almeida Junior D R,Sandim H R Z,et al.Misorientation distribution between martensite and austenite in Fe-31 wt%Ni-0.01 wt%C[J].Acta Mater.,2018,143:227
[34]Bain E C.The nature of martensite[J].Trans.Am.Inst.Min.Metall.Eng.,1924,70:25
[35]Greninger A B,Troiano A R.Crystallography of austenite decomposition[J].Trans.Am.Inst.Min.Metall.Eng.,1940,140:307
[36]King A D,Bell T.Crystallography of grain boundary proeutectoid ferrite[J].Metall.Trans.,1975,6A:1419
[37]Grong?,Kluken A O,Nylund H K,et al.Catalyst effects in heterogeneous nucleation of acicular ferrite[J].Metall.Mater.Trans.,1995,26A:525
[38]Spanos G,Kral M V.The proeutectoid cementite transformation in steels[J].Int.Mater.Rev.,2009,54:19
[39]Xu W S,Zhang W Z.A new orientation relationship between cementite and austenite and coexistence of pseudo-primary and secondary dislocations in the habit plane[J].Philos.Mag.,2018,98:75
[40]Darken L S,Fisher P M.Decomposition of Austenite by Diffusional Processes[M].New York:Intersciences Publishers,1962:249