SDC99冷作模具钢深冷处理试验及数值分析

Experimental study and numerical simulation of cryogenic treatment of cold-work die steel SDC99

通过试验实测冷作模具钢SDC99的低温参数,结合沸腾换热经验模型求解沸腾换热系数,建立有限元数值分析模型,对SDC99冷作模具钢试件深冷处理过程进行数值模拟。研究表明,试件心部和表面的冷却状况差异较大,尤其是温度和冷却速度。然而,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内部的1/3厚度内,而在试件心部温度和冷却速度变化比较平缓。模拟结果与试验实测数据比较吻合,最大相对偏差为10.58%,这说明采用数值分析方法能较好的再现试件在深冷处理过程中的动态温度场变化规律,为后续组织性能评估以及深冷处理工艺的制定提供依据。

Using the low temperature physical parameters of cold-work die steel SDC99 obtained from experimental test and the boiling heat transfer coefficient acquired by an empirical formula method, a finite element model is built to simulate the cryogenic treatment of a cold-work die steel specimen immersed in liquid nitrogen bath. The investigation suggests that the differences in temperature and cooling rate between surface and core of the specimen is very significant. However, it should be emphasized that the acute changes in temperature and cooling rate are mainly concentrated on the specimen surface region about 1/3 of the sample thickness, while these changes occur in a slow and gentle manner at the core region of specimen. The simulation results are identical with the data obtained from the experimental test and the maximum percentage deviation between experimental data and simulation results is 10.58%. It demonstrates that the numerical model adopted in this study can correctly reflect the change rules of temperature field during cryogenic treatment, which can provides a theoretical guidance for evaluating microstructure and properties of the cold-work die steel and optimizing its cryogenic treatment process.