Microstructure and mechanical properties in core of a carburizing 20CrNi2MoV bearing steel subjected to cryogenic treatment were investigated. Conventional treatment sample was quenched and tempered at 180 °C for 2 h. Cryogenic treatment samples were quenched, cryogenically treated at − 80 and − 196 °C for 4 h, slowly returned to room temperature and thereafter tempered at 180 °C for 2 h, and finally tempered at 180 °C for 2 h. The scanning electron microscope, electron backscattering diffraction, X-ray diffraction and transmission electron microscope were adopted for microstructure characterization. The results show that cryogenic treatment increases the fraction of high-angle grain boundaries and the precipitation of finely dispersed carbides in the matrix, decreases the volume fraction of inter-lath retained austenite, and hence improves the strength and hardness. Compared with the conventional treatment, the hardness, yield strength and ultimate tensile strength of the steel after cryogenic treatment are increased by 11.7%, 12.6% and 18.3%, respectively, while the impact energy is decreased by 9.8%.

研究了渗碳20CrNi2MoV轴承钢深冷处理后铁心的组织和力学性能。常规处理样品在180°C淬火回火2 h。将低温处理样品淬火，在-80和-196°C下进行低温处理4 h，然后缓慢恢复至室温，然后在180°C下回火2 h，最后在180°C下回火2 h。采用扫描电子显微镜，电子背散射衍射，X射线衍射和透射电子显微镜进行微观结构表征。结果表明，低温处理增加了基体中高角度晶界的分数和细分散的碳化物的析出，降低了板条间残留奥氏体的体积分数，因此提高了强度和硬度。与常规处理相比，低温处理后的钢的硬度，屈服强度和极限抗拉强度分别提高了11.7％，12.6％和18.3％，而冲击能降低了9.8％。