以自主开发的SDC99冷作模具钢C型环试样为研究对象, 结合材料低温物性参数和由沸腾换热模型求解获得的沸腾换热系数, 基于金属-热-力耦合理论建立了深冷处理的有限元模型, 对C型环试样深冷处理进行数值模拟, 研究了其温度场和组织场的演变特征。结果表明: 深冷处理过程中, C型环试样缺口与中心部位的温度和冷却速率存在较大差异, 尤其是冷却速率差异较大; 深冷处理能有效减少残余奥氏体的含量, 其体积分数由初始的15%减少到2.3%, 同时马氏体的体积分数由85%提高至97.7%; 深冷处理后的残余奥氏体分布不均, 主要聚集在试样的缺口附近; 模拟结果与XRD试验测试结果非常吻合。

Taking a new developed cold work die steel SDC99 C-ring specimen as the research object and combining with the low temperature physical parameters and the boiling heat transfer coefficient acquired by an empirical formula method, a finite element model based on metallo-thermo-mechanical coupled theory was built up to simulate the deep cryogenic treatment(DCT)for a C-ring specimen and to explore the essential characteristic of temperature and microstructure evolution. Results show that during DCT, the differences in temperature and cooling rate between the gap and core regions of C-ring specimen were very significant, especially in the cooling rate. Subjected to DCT, the amount of retained austenite contained in C-ring specimen markedly decreased from 15 vol.% at initial to 2.3 vol.% at last, while the volume fraction of martensite increased from 85% to 97.7%. After DCT, the retained austenite nonuniformly distributed but principally congregated near the gap region of specimen. Compared with the quantitative phase analysis by XRD, the predicted results present a quite good accuracy.