低碳Si-Mn钢直接淬火-等温配分工艺中组织演变

以低碳Si-Mn钢为研究对象,在传统淬火-配分工艺中引入压缩变形,研究了压缩变形对组织演变的影响以及实验钢在不同等温配分条件下的显微结构特征.结果表明,引入高温变形处理后,试样具有更加精细的显微结构,同时显微组织中含有较高比例的大角度晶界,由无变形条件下的65.7%提高至72.5%;在相变及碳配分过程中,晶界以及板条边界附近易形成碳富集区;随配分时间延长,显微组织呈回火转变趋势,当配分时间延长至1 500 s时,组织中出现较大量的碳化物析出相,残余奥氏体体积分数降低至7.9%.

Microstructure Evolution of Low Carbon Si-Mn Steel During Direct Quenching and Isothermal Partitioning

Compression deformation was introduced into the conventional quenching and partitioning process for low carbon Si-Mn steel.Effects of the hot deformation on microstructure evolution and microstructure characteristics of specimens treated by various isothermal partitioning processes were investigated. The results showed that the microstructure is refined and the fraction of high-angle grain boundary increases from 65.7% to 72.5% due to the hot deformation. Carbon-rich areas formed during transformation and partitioning process are mostly observed at the boundaries of prior austenite grains and martensite laths. With the increase of the partitioning time，the microstructure shows a tendency to tempering transformation. When the partitioning time is up to 1500s， a great number of carbides are formed and the volume fraction of retained austenite decreases to 7.9%.