一种新型高强度高塑性冷轧中锰钢的组织和力学性能
|
摘要
研究了两相区退火温度对一种新型冷轧中锰钢(0.2C-5Mn-0.6Si-3Al,质量分数,%)显微组织及拉伸性能的影响。结果表明,在退火温度为730℃时,冷轧中锰钢可获得优异的强度与塑性配合,即抗拉强度为1062 MPa,总伸长率为58.2%,强塑积为61.8 GPa·%。随着退火温度升高,逆转变奥氏体逐渐粗化,且由片层状组织形态逐渐向等轴状组织形态转变,在一定退火温度下可获得奥氏体晶粒尺寸分布较为宽泛的多尺度的组织形态。这种多尺度组织形态的残余奥氏体具有适当的机械稳定性,能够产生连续不断的相变诱发塑性(TRIP)效应。连续不断的TRIP效应与铁素体在变形过程中的良好配合,是冷轧中锰钢获得高强度、高塑性的主要原因。冷轧中锰钢拉伸断裂的裂纹主要萌生于软相的铁素体(δ-铁素体)及超细晶铁素体与形变诱导马氏体(残余奥氏体)的界面处。
Recently, energy conservation, environmental protection and security are the main factors considered by the automotive manufacturers. Medium-Mn steel with excellent combination of specific strength and ductility have been regarded as the potential candidates for automotive applications. The excellent combination of specific strength and ductility depends on the microstructure under different heat treatment processes of the steels. Therefore, the relationship of the combination of specific strength and ductility and microstructure should be studied in detail. A new alloy system of aluminum-containing mediumMn steel was developed in this study. The addition of aluminum stabilizes a-ferrite, and facilitates the presence of d-ferrite during solidification. The addition of Mn and C compensates the effect of aluminum on phase stability and ensures austenite formation. In this investigation, the effects of intercritical annealing temperature on the microstructure and tensile properties of a newly designed cold-rolled aluminumcontaining medium-Mn steel(0.2 C-5 Mn-0.6 Si-3 Al, mass fraction, %) were investigated by SEM, XRD and uniaxial tensile tests. The tensile results show that an excellent combination of ultimate tensile strength(sb) of 1062 MPa, total elongation(δ) of 58.2% and sb×δ of 61.8 GPa·% could be obtained after annealing at 730 ℃. The inverted austenite of the cold-rolled steel coarsenes and gradually changes its morphology from mainly lamellar to mainly equiaxed with increasing intercritical annealing temperature,and a duplex microstructure consisting of multi-scale retained austenite could be obtained at 730 ℃,which possesses suitable mechanical stability and thus presents prolonged transformation-induced plasticity(TRIP) effect during tensile deformation. This kind of sustainable TRIP effect and the cooperative deformation of ferrite are responsible for the superior mechanical properties. The investigation of tensile fracture behavior shows that the nucleation and growth of voids occurred mainly at the interfaces between soft ferrite and hard martensite induced by deformation.
Recently, energy conservation, environmental protection and security are the main factors considered by the automotive manufacturers. Medium-Mn steel with excellent combination of specific strength and ductility have been regarded as the potential candidates for automotive applications. The excellent combination of specific strength and ductility depends on the microstructure under different heat treatment processes of the steels. Therefore, the relationship of the combination of specific strength and ductility and microstructure should be studied in detail. A new alloy system of aluminum-containing mediumMn steel was developed in this study. The addition of aluminum stabilizes a-ferrite, and facilitates the presence of d-ferrite during solidification. The addition of Mn and C compensates the effect of aluminum on phase stability and ensures austenite formation. In this investigation, the effects of intercritical annealing temperature on the microstructure and tensile properties of a newly designed cold-rolled aluminumcontaining medium-Mn steel(0.2 C-5 Mn-0.6 Si-3 Al, mass fraction, %) were investigated by SEM, XRD and uniaxial tensile tests. The tensile results show that an excellent combination of ultimate tensile strength(sb) of 1062 MPa, total elongation(δ) of 58.2% and sb×δ of 61.8 GPa·% could be obtained after annealing at 730 ℃. The inverted austenite of the cold-rolled steel coarsenes and gradually changes its morphology from mainly lamellar to mainly equiaxed with increasing intercritical annealing temperature,and a duplex microstructure consisting of multi-scale retained austenite could be obtained at 730 ℃,which possesses suitable mechanical stability and thus presents prolonged transformation-induced plasticity(TRIP) effect during tensile deformation. This kind of sustainable TRIP effect and the cooperative deformation of ferrite are responsible for the superior mechanical properties. The investigation of tensile fracture behavior shows that the nucleation and growth of voids occurred mainly at the interfaces between soft ferrite and hard martensite induced by deformation.
引文
[1]Fan C G,Dong H,Yong Q L,et al.Research development of ultrahigh strength low alloy steels[J].Mater.Mech.Eng.,2006,30(8):1(范长刚,董瀚,雍岐龙等.低合金超高强度钢的研究进展[J].机械工程材料,2006,30(8):1)
[2]Suh D W,Kim S J.Medium Mn transformation-induced plasticity steels:Recent progress and challenges[J].Scr.Mater.,2017,126:63
[3]Lee Y K,Han J.Current opinion in medium manganese steel[J].Mater.Sci.Technol.,2015,31:843
[4]Wang L D,Ding F C,Wang B M,et al.Influence of superfine substructure on toughness of low-alloying ultra-high strength structure steel[J].Acta Metall.Sin.,2009,45:292(王六定,丁富才,王佰民等.低合金超高强度钢亚结构超细化对韧性的影响[J].金属学报,2009,45:292)
[5]Dong H,Cao W Q,Shi J,et al.Microstructure and performance control technology of the 3rd generation auto sheet steels[J].Iron Steel,2011,46(6):1(董瀚,曹文全,时捷等.第3代汽车钢的组织与性能调控技术[J].钢铁,2011,46(6):1)
[6]Shi J,Sun X J,Wang M Q,et al.Enhanced work-hardening behavior and mechanical properties in ultrafine-grained steels with largefractioned metastable austenite[J].Scr.Mater.,2010,63:815
[7]Shi J,Cao W Q,Dong H.Ultrafine grained high strength low alloy steel with high strength and high ductility[J].Mater.Sci.Forum,2010,654-656:238
[8]Miller R L.Ultrafine-grained microstructures and mechanical properties of alloy steels[J].Metall.Mater.Trans.,1972,3B:905
[9]Park K T,Lee E G,Lee C S.Reverse austenite transformation behavior of equal channel angular pressed low carbon ferrite/pearlite steel[J].ISIJ Int.,2007,47:294
[10]Nakada N,Tsuchiyama T,Takaki S,et al.Variant selection of reversed austenite in lath martensite[J].ISIJ Int.,2007,47:1527
[11]Hara T,Maruyama N,Shinohara Y,et al.Abnormal a to g transformation behavior of steels with a martensite and bainite microstructure at a slow reheating rate[J].ISIJ Int.,2009,49:1792
[12]Wang C,Shi J,Wang C Y,et al.Development of ultrafine lamellar ferrite and austenite duplex structure in 0.2C5Mn steel during ART-annealing[J].ISIJ Int.,2011,51:651
[13]Xu Y B,Hu Z P,Zou Y,et al.Effect of two-step intercritical annealing on microstructure and mechanical properties of hot-rolled medium manganese TRIP steel containing d-ferrite[J].Mater.Sci.Eng.,2017,A688:40
[14]Shao C W,Hui W J,Zhang Y J,et al.Microstructure and mechanical properties of hot-rolled medium-Mn steel containing 3%aluminum[J].Mater.Sci.Eng.,2017,A682:45
[15]Cai Z H,Ding H,Ying Z Y,et al.Microstructural evolution and deformation behavior of a hot-rolled and heat treated Fe-8Mn-4Al-0.2C steel[J].J.Mater.Eng.Perform.,2014,23:1131
[16]Matlock D K,Speer J G,De Moor E,et al.Recent developments in advanced high strength sheet steels for automotive applications:An overview[J].JESTECH,2012,15:1
[17]Lacroix G,Pardoen T,Jacques P J.The fracture toughness of TRIP-assisted multiphase steels[J].Acta Mater.,2008,56:3900
[18]Chin K G,Kang C Y,Shin S Y,et al.Effects of Al addition on deformation and fracture mechanisms in two high manganese TWIPsteels[J].Mater.Sci.Eng.,2011,A528:2922
[19]Choi H,Lee S,Lee J,et al.Characterization of fracture in medium Mn steel[J].Mater.Sci.Eng.,2017,A687:200
[20]Fan X.Metallic X-Ray Physics[M].Beijing:Mechanical Industry Press,1989:159(范雄.金属X射线学[M].北京:机械工业出版社,1989:159)
[21]Zhao X L,Zhang Y J,Shao C W,et al.Hydrogen embrittlement of intercritically annealed cold-rolled 0.1C-5Mn steel[J].Acta Metall.Sin.,2018,54:1031(赵晓丽,张永健,邵成伟等.两相区退火处理冷轧0.1C-5Mn中锰钢的氢脆敏感性[J].金属学报,2018,54:1031)
[22]Zhang M D,Cao W Q,Dong H,et al.Element partitioning effect on microstructure and mechanical property of the micro-laminated Fe-Mn-Al-C-dual phase steel[J].Mater.Sci.Eng.,2016,A654:193
[23]Hu B,Luo H W.A strong and ductile 7Mn steel manufactured by warm rolling and exhibiting both transformation and twinning induced plasticity[J].J.Alloys Compd.,2017,725:684
[24]Jung Y S,Lee Y K,Matlock D K,et al.Effect of grain size on strain-induced martensitic transformation start temperature in an ultrafine grained metastable austenitic steel[J].Met.Mater.Int.,2011,17:553
[25]Embury D,Bouaziz O.Steel-based composites:Driving forces and classification[J].Annu.Rev.Mater.Res.,2010,40:213
[26]Cai Z H,Ding H,Misra R D K,et al.Austenite stability and deformation behavior in a cold-rolled transformation-induced plasticity steel with medium manganese content[J].Acta Mater.,2015,84:229
[27]Li Z C,Ding H,Cai Z H,et al.Mechanical properties and austenite stability in hot-rolled 0.2C-1.6/3.2Al-6Mn-Fe TRIP steel[J].Mater.Sci.Eng.,2015,A639:559
[28]Li Z C,Misra R D K,Cai Z H,et al.Mechanical properties and deformation behavior in hot-rolled 0.2C-1.5/3Al-8.5Mn-Fe TRIPsteel:The discontinuous TRIP effect[J].Mater.Sci.Eng.,2016,A673:63
[29]Sugimoto K I,Usui N,Kobayashi M,et al.Effects of volume fraction and stability of retained austenite on ductility of TRIP-aided dual-phase steels[J].ISIJ Int.,1992,32:1311
[30]Sugimoto K,Usui N,Kobayashi M,et al.Ductility and straininduced transformation in a high-strength transformation-induced plasticity-aided dual-phase steel[J].Metall.Mater.Trans.,1992,23A:3685
[31]Takaki S,Fukimaga K,Syarif J,et al.Effect of grain refinement on thermal stability of metastable austenitic steel[J].Mater.Trans.,2004,45:2245
[32]Matsuoka Y,Iwasaki T,Nakada N,et al.Effect of grain size on thermal and mechanical stability of austenite in metastable austenitic stainless steel[J].ISIJ Int.,2013,53:1224
[33]Avramovic-Cingara G,Saleh C A R,Jain M K,et al.Void nucleation and growth in dual-phase steel 600 during uniaxial tensile testing[J].Metall.Mater.Trans.,2009,40A:3117
[34]Han S K,Margolin H.Void formation,void growth and tensile fracture of plain carbon steel and a dual-phase steel[J].Mater.Sci.Eng.,1989,A112:133
[35]Erdogan M.The effect of new ferrite content on the tensile fracture behaviour of dual phase steels[J].J.Mater.Sci.,2002,37:3623
[2]Suh D W,Kim S J.Medium Mn transformation-induced plasticity steels:Recent progress and challenges[J].Scr.Mater.,2017,126:63
[3]Lee Y K,Han J.Current opinion in medium manganese steel[J].Mater.Sci.Technol.,2015,31:843
[4]Wang L D,Ding F C,Wang B M,et al.Influence of superfine substructure on toughness of low-alloying ultra-high strength structure steel[J].Acta Metall.Sin.,2009,45:292(王六定,丁富才,王佰民等.低合金超高强度钢亚结构超细化对韧性的影响[J].金属学报,2009,45:292)
[5]Dong H,Cao W Q,Shi J,et al.Microstructure and performance control technology of the 3rd generation auto sheet steels[J].Iron Steel,2011,46(6):1(董瀚,曹文全,时捷等.第3代汽车钢的组织与性能调控技术[J].钢铁,2011,46(6):1)
[6]Shi J,Sun X J,Wang M Q,et al.Enhanced work-hardening behavior and mechanical properties in ultrafine-grained steels with largefractioned metastable austenite[J].Scr.Mater.,2010,63:815
[7]Shi J,Cao W Q,Dong H.Ultrafine grained high strength low alloy steel with high strength and high ductility[J].Mater.Sci.Forum,2010,654-656:238
[8]Miller R L.Ultrafine-grained microstructures and mechanical properties of alloy steels[J].Metall.Mater.Trans.,1972,3B:905
[9]Park K T,Lee E G,Lee C S.Reverse austenite transformation behavior of equal channel angular pressed low carbon ferrite/pearlite steel[J].ISIJ Int.,2007,47:294
[10]Nakada N,Tsuchiyama T,Takaki S,et al.Variant selection of reversed austenite in lath martensite[J].ISIJ Int.,2007,47:1527
[11]Hara T,Maruyama N,Shinohara Y,et al.Abnormal a to g transformation behavior of steels with a martensite and bainite microstructure at a slow reheating rate[J].ISIJ Int.,2009,49:1792
[12]Wang C,Shi J,Wang C Y,et al.Development of ultrafine lamellar ferrite and austenite duplex structure in 0.2C5Mn steel during ART-annealing[J].ISIJ Int.,2011,51:651
[13]Xu Y B,Hu Z P,Zou Y,et al.Effect of two-step intercritical annealing on microstructure and mechanical properties of hot-rolled medium manganese TRIP steel containing d-ferrite[J].Mater.Sci.Eng.,2017,A688:40
[14]Shao C W,Hui W J,Zhang Y J,et al.Microstructure and mechanical properties of hot-rolled medium-Mn steel containing 3%aluminum[J].Mater.Sci.Eng.,2017,A682:45
[15]Cai Z H,Ding H,Ying Z Y,et al.Microstructural evolution and deformation behavior of a hot-rolled and heat treated Fe-8Mn-4Al-0.2C steel[J].J.Mater.Eng.Perform.,2014,23:1131
[16]Matlock D K,Speer J G,De Moor E,et al.Recent developments in advanced high strength sheet steels for automotive applications:An overview[J].JESTECH,2012,15:1
[17]Lacroix G,Pardoen T,Jacques P J.The fracture toughness of TRIP-assisted multiphase steels[J].Acta Mater.,2008,56:3900
[18]Chin K G,Kang C Y,Shin S Y,et al.Effects of Al addition on deformation and fracture mechanisms in two high manganese TWIPsteels[J].Mater.Sci.Eng.,2011,A528:2922
[19]Choi H,Lee S,Lee J,et al.Characterization of fracture in medium Mn steel[J].Mater.Sci.Eng.,2017,A687:200
[20]Fan X.Metallic X-Ray Physics[M].Beijing:Mechanical Industry Press,1989:159(范雄.金属X射线学[M].北京:机械工业出版社,1989:159)
[21]Zhao X L,Zhang Y J,Shao C W,et al.Hydrogen embrittlement of intercritically annealed cold-rolled 0.1C-5Mn steel[J].Acta Metall.Sin.,2018,54:1031(赵晓丽,张永健,邵成伟等.两相区退火处理冷轧0.1C-5Mn中锰钢的氢脆敏感性[J].金属学报,2018,54:1031)
[22]Zhang M D,Cao W Q,Dong H,et al.Element partitioning effect on microstructure and mechanical property of the micro-laminated Fe-Mn-Al-C-dual phase steel[J].Mater.Sci.Eng.,2016,A654:193
[23]Hu B,Luo H W.A strong and ductile 7Mn steel manufactured by warm rolling and exhibiting both transformation and twinning induced plasticity[J].J.Alloys Compd.,2017,725:684
[24]Jung Y S,Lee Y K,Matlock D K,et al.Effect of grain size on strain-induced martensitic transformation start temperature in an ultrafine grained metastable austenitic steel[J].Met.Mater.Int.,2011,17:553
[25]Embury D,Bouaziz O.Steel-based composites:Driving forces and classification[J].Annu.Rev.Mater.Res.,2010,40:213
[26]Cai Z H,Ding H,Misra R D K,et al.Austenite stability and deformation behavior in a cold-rolled transformation-induced plasticity steel with medium manganese content[J].Acta Mater.,2015,84:229
[27]Li Z C,Ding H,Cai Z H,et al.Mechanical properties and austenite stability in hot-rolled 0.2C-1.6/3.2Al-6Mn-Fe TRIP steel[J].Mater.Sci.Eng.,2015,A639:559
[28]Li Z C,Misra R D K,Cai Z H,et al.Mechanical properties and deformation behavior in hot-rolled 0.2C-1.5/3Al-8.5Mn-Fe TRIPsteel:The discontinuous TRIP effect[J].Mater.Sci.Eng.,2016,A673:63
[29]Sugimoto K I,Usui N,Kobayashi M,et al.Effects of volume fraction and stability of retained austenite on ductility of TRIP-aided dual-phase steels[J].ISIJ Int.,1992,32:1311
[30]Sugimoto K,Usui N,Kobayashi M,et al.Ductility and straininduced transformation in a high-strength transformation-induced plasticity-aided dual-phase steel[J].Metall.Mater.Trans.,1992,23A:3685
[31]Takaki S,Fukimaga K,Syarif J,et al.Effect of grain refinement on thermal stability of metastable austenitic steel[J].Mater.Trans.,2004,45:2245
[32]Matsuoka Y,Iwasaki T,Nakada N,et al.Effect of grain size on thermal and mechanical stability of austenite in metastable austenitic stainless steel[J].ISIJ Int.,2013,53:1224
[33]Avramovic-Cingara G,Saleh C A R,Jain M K,et al.Void nucleation and growth in dual-phase steel 600 during uniaxial tensile testing[J].Metall.Mater.Trans.,2009,40A:3117
[34]Han S K,Margolin H.Void formation,void growth and tensile fracture of plain carbon steel and a dual-phase steel[J].Mater.Sci.Eng.,1989,A112:133
[35]Erdogan M.The effect of new ferrite content on the tensile fracture behaviour of dual phase steels[J].J.Mater.Sci.,2002,37:3623