冷轧及退火制备的超细晶粒双相Mn12Ni2MoTi(Al)钢

(湖南大学材料科学与工程学院, 长沙 410082) 摘 要 采用 XRD, SEM, TEM, 硬度测试和拉伸实验研究了冷轧 Mn12Ni2MoTi(Al)钢经不同工艺退火后 的显微组织及力学性能. 结果表明, 马氏体 Mn12Ni2MoTi(Al)钢经 65%冷轧及 710~745 °C退火处理后转变 成主要由奥氏体晶粒和铁素体晶粒组成的亚微米级超细晶粒双相组织, 并且弥散分布着第二相析出物颗粒; 在退火中形成的富Ti, Mo及Si的第二相颗粒阻碍了超细再结晶晶粒的粗化, 从而提高了钢的屈服强度和热 稳定性; 经 710 °C, 24 h 长时间退火后, 超细晶粒双相钢的平均晶粒尺寸仍然小于 500 nm; 超细晶粒双相钢 延伸率随室温奥氏体体积分数增加而增加, 室温奥氏体体积分数随退火温度升高或退火时间延长先增加后 降低, 且在 745 °C, 0.5 h 退火时达到最大值. 超细晶粒钢的屈服强度和总延伸率可达到 900 MPa 和 23%以 上, 比同种材料淬火马氏体钢提高了约一倍. 关键词 超细晶粒双相钢, 第二相强化, 相变诱发塑性(TRIP)效应, 形变热处理, 力学性能 中图法分类号 TG142.1 文献标识码 A 文章编号 0412-1961(2016)×-××-× AN ULTRAFINE GRAINED DUPLEX Mn12Ni2MoTi(Al) STEEL FABRICATED BY COLD ROLLING AND ANNEALING YIN Yanqi, WU Cuilan, XIE Pan, ZHU Kai, TIAN Songli, HAN Mei, CHEN Jianghua College of Materials Science and Engineering, Hunan University, Changsha 410082, China Correspondent: WU Cuilan, professor, Tel: (0731)88664010, E-mail: cuilanwu@hnu.edu.cn Supported by National Natural Science Foundation of China (Nos.11427806 and 51371081) Manuscript received 200*—**—**, in revised form 200*—**—** ABSTRACT For decades, transformation induced plasticity (TRIP) assisted steels with high tensile strength and exceptional ductility at room temperature have attracted a great deal of attentions. Their applications are often limited due to the low yield strength.In this work, an ultrafine grained (UFG) duplex Mn12Ni2MoTi(Al) TRIP steel with high yield strength and good ductility is fabricated by cold rolling and subsequent annealing at