冷轧及退火制备的超细晶粒双相Mn12Ni2MoTi(Al)钢  

AN ULTRAFINE GRAINED DUPLEX Mn12Ni2MoTi(Al) STEEL FABRICATED BY COLD ROLLING AND ANNEALING

作　　者：尹炎祺 伍翠兰[1] 谢盼[1] 朱恺[1] 田松栗 韩梅[1] 陈江华[1] 

机构地区：[1]湖南大学材料科学与工程学院,长沙410082

出　　处：《金属学报》2016年第12期1527-1535,共9页Acta Metallurgica Sinica

基　　金：国家自然科学基金项目11427806和51371081资助~~

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℃退火处理后转变成主要由奥氏体晶粒和铁索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℃，24h长时间退火后，超细晶粒双相钢的平均晶粒尺寸仍然小于500nm,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℃，0．5h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900MPa和23％以上，比同种材料淬火马氏体钢提高了约一倍．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 710- 745 ℃. The microstructure and mechanical properties of the steels with different heat treatment conditions are in- vestigated by means of XRD, SEM, TEM, hardness and tensile tests. It is found that after annealing at 7 1 0-745 ℃, the deformation microstructure of the cold-rolled samples has transformed into a sub-micron UFG duplex micro- structure consisting of austenite, ferrite and dispersed second-phase precipitations. The second-phase precipitations formed during annealing are rich in Ti, Mo and Si, and play an important role in preventing the ultrafine grains from coarsening, which results in high yield strength and good thermal stability. After annealing at 710 ℃ for 24 h, the average grain size of the UFG steel is still less than 500 nm. The elongation of the UFG duplex steel is increas- ing with the increment of the volume fraction of austenite in the UFG duplex steel at room temperature. The vol- ume fraction of austenite in the UFG duplex steel at room temperature first increases and then decreases with the annealing temperature and time increasing, and reaches the maximum value when annealing at 745 ℃ for 0.5 h. The yield strength and total elongation of the UFG steel can be as large as 900 MPa and 23%, respectively, whichare about double those of the quenched martensitic sample.

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 

分 类 号：TG142.1[一般工业技术—材料科学与工程]