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结合低温材料参数以及液氮浴沸腾换热系数,基于金属-热-力耦合理论建立深冷处理数值分析模型,再现新型冷作模具钢Cr8Mo2SiV(SDC99)的深冷处理过程。同时,通过设计深冷处理温度快速测量装置验证模拟结果的准确性。结果表明,深冷处理过程中试样心表温差和冷却速度的差异较大。这种温度和冷却速度的剧烈变化主要集中于从试件表面至心部的1/3厚度内。经过深冷处理后,试样内残余奥氏体将继续向马氏体转变,其最终体积分数减小为2.3%。模拟结果与实验结果非常吻合,这表明采用的数值分析方法能准确地捕捉试件在深冷处理过程中温度场和组织场的变化规律,能为深冷处理工艺的合理制定提供理论依据和借鉴。
Combined with the parameters of low temperature materials and the boiling heat transfer coefficient of liquid nitrogen bath, a numerical simulation model of cryogenic treatment was established based on the theory of metal - thermo - mechanical coupling, and the cryogenic treatment process of the new cold work die steel Cr8Mo2SiV (SDC99) was reproduced. Simultaneously, the accuracy of the simulation results was verified by designing a cryogenic processing temperature rapid measurement device. The results show that the difference between the surface temperature difference and the cooling rate of the sample in the cryogenic treatment is quite different. The dramatic changes in temperature and cooling rate are mainly concentrated within 1/3 of the thickness from the specimen surface to the heart. After cryogenic treatment, the retained austenite in the sample will continue to be transformed into martensite with the final volume fraction decreasing to 2.3%. The simulation results are in good agreement with the experimental results, which shows that the numerical analysis method can accurately capture the variation of temperature field and field in the cryogenic treatment process, which can provide theoretical basis and reference for the reasonable formulation of cryogenic treatment process.