Liang Xiaokai, Fu Hang, Cui Mei, Liu Gang
Department of Structural Steels, Central Iron and Steel Research Institute Company Limited, Beijing 100081, China.
NCS Testing Technology Co., Ltd., Beijing 100081, China.
Materials (Basel). 2022 Mar 15;15(6):2162. doi: 10.3390/ma15062162.
The effect of intercritical tempering temperature (TT) on the microstructure evolution and mechanical properties of 3.6Mn medium manganese steel, which contained martensite and austenite, was investigated by X-ray diffraction, electron backscattering diffraction and transmission electron microscopy, as well as Thermo-Calc calculation. The results showed that the volume fraction of reversed austenite (RA) increased firstly and then decreased with the increasing TT in the range of 550~650 °C. When the TT was below 620 °C, lath-like RA with good stability was mainly displayed between martensite laths and its size is about 100 nm. When the TT was higher than 650 °C, larger-size and block RA was formed in the martensite block boundaries, and part of the RA transformed into fresh martensite during cooling. The yield strength and tensile strength of the experimental steels decreased gradually as the TT increased, but the tensile strength increased gradually with the formation of block RA and fresh martensite. Lath-like RA could significantly improve the toughness and plasticity with slight loss of yield strength, but block RA decreased slightly them.
通过X射线衍射、电子背散射衍射、透射电子显微镜以及Thermo-Calc计算，研究了临界区回火温度（TT）对含马氏体和奥氏体的3.6Mn中锰钢微观组织演变及力学性能的影响。结果表明，在550~650℃范围内，随着TT升高，逆转变奥氏体（RA）的体积分数先增加后降低。当TT低于620℃时，主要在马氏体板条间出现稳定性良好的板条状RA，其尺寸约为100nm。当TT高于650℃时，在马氏体块边界形成尺寸较大的块状RA，且部分RA在冷却过程中转变为新鲜马氏体。试验钢的屈服强度和抗拉强度随TT升高逐渐降低，但抗拉强度随着块状RA和新鲜马氏体的形成而逐渐增加。板条状RA能在屈服强度略有损失的情况下显著提高韧性和塑性，但块状RA会使其略有降低。
