Wang Feilong, Ye Xiaoyu, Ren Shoubin, Zhang Kaihua, Liang Xiaokai, Liu Gang
State Key Laboratory of New Metal Materials, University of Science and Technology Beijing, Beijing 100083, China.
State Key Laboratory of Vanadium and Titanium Resources Comprehensive Utilization, Pangang Group Research Institute Co., Ltd., Panzhihua 617000, China.
Materials (Basel). 2022 Mar 25;15(7):2425. doi: 10.3390/ma15072425.
A novel multi-step heat treatment process was performed for 0.2C-5Mn steel, and the effect of intercritical annealing (IA) durations on the microstructure evolution and mechanical properties was studied. The results showed that the content of primary reversed austenite (PRA) hardly changed as the IA time increased from 6 h to 50 h, but only less than 10% of PRA remained after being tempered at 200 °C due to the appearance of secondary martensite (SM). The final microstructure contained SM, the primary martensite (PM), and RA, which was protected by the SM so that the transformation-induced plasticity (TRIP) effect was unlikely to occur. Meanwhile, the (Ti, V, Mo)C particle sizes were 14.27, 14.68 and 15.65 nm for the intermediate processes of IA-6 h, IA-12 h, and IA-50 h, respectively. As the IA time increased from 6 h to 50 h, both the dislocation and precipitation strengthening increment decreased. As a result, the best mechanical properties were obtained from the intermediate process of IA-12 h, with a yield strength of 1115.5 MPa, tensile strength of 1573.5 MPa, and -20 °C impact energy of 30.4 J.
对0.2C-5Mn钢进行了一种新型的多步热处理工艺，并研究了临界区退火（IA）持续时间对微观结构演变和力学性能的影响。结果表明，随着IA时间从6小时增加到50小时，初生逆奥氏体（PRA）的含量几乎没有变化，但由于二次马氏体（SM）的出现，在200°C回火后仅保留了不到10%的PRA。最终的微观结构包含SM、初生马氏体（PM）和残余奥氏体（RA），RA被SM保护，因此不太可能发生相变诱发塑性（TRIP）效应。同时，对于IA-6小时、IA-12小时和IA-50小时的中间过程，（Ti，V，Mo）C颗粒尺寸分别为14.27、14.68和15.65纳米。随着IA时间从6小时增加到50小时，位错强化增量和析出强化增量均下降。结果，在IA-12小时的中间过程中获得了最佳力学性能，屈服强度为1115.5兆帕，抗拉强度为1573.5兆帕，-20°C冲击能量为30.4焦。
