一种新型高强度高塑性冷轧中锰钢的组织和力学性能  

Microstructure and Mechanical Properties of a Novel Cold Rolled Medium-Mn Steel with Superior Strength and Ductility

作　　者：邵成伟[1] 惠卫军[1] 张永健[1] 赵晓丽 翁宇庆[1] SHAO Chengwei;HUI Weijun;ZHANG Yongjian;ZHAO Xiaoli;WENG Yuqing(School of Mechanical,Electronic and Control Engineering,Beijing Jiaotong University,Beijing 100044,China)

机构地区：[1]北京交通大学机械与电子控制工程学院,北京100044

出　　处：《金属学报》2019年第2期191-201,共11页Acta Metallurgica Sinica

基　　金：北京交通大学人才基金项目No.M14RC00010~~

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 a

关 键 词：冷轧中锰钢 两相区退火 微观组织 残余奥氏体稳定性 

分 类 号：TG111[金属学及工艺—物理冶金] TGL42[金属学及工艺—金属学]