18CrNiMo7-6钢圆柱试件淬火过程数值模拟

Numerical Simulation of the Quenching Process of 18CrNiMo7- 6 Steel Cylinder Specimen

采用有限元分析方法,利用SYSWELD软件模拟18CrNiMo7-6钢圆柱试件渗碳及淬火过程,并分析其渗碳场、温度场及硬度的变化规律和分布状态。模拟结果表明,渗碳过程中,圆柱试件外表面含碳质量分数先增大后减小,而心部含碳质量分数基本保持不变;淬火过程中,圆柱试件截面沿径向温差先增大后减小,冷却到9.8 s时,温差最大,为293℃;冷却到12.0 s时,外表面处率先发生马氏体转变;冷却到47.2 s时,圆柱试件心部温度为281℃,整个试件几乎都完成马氏体转变;圆柱试件硬度值沿径向从外表面向心部逐渐递减,很符合18CrNiMo7-6钢热处理后的性能。

By means of the finite element analysis, the SYSWELD software was used to simulate the carburizing and quenching process of 18CrNiMo7 -6 steel cylinder specimen and analyze the variation law and distribution of its carburizing field, temperature field and hardness. The simulation shows that in the process of carburizing, the carbon mass fraction of the external surface of the specimen first increases and then decreases, but the carbon mass fraction of the specimen center basically remains unchanged. In the process of quenching, the temperature differ- ence of the specimen cross-section first increases and then decreases in the radial direction. When it cools up to 9.8 s, the temperature difference reaches the maximum which is 293℃ ; when it cools up to 12.0 s, the martensitic transformation occurs first on its external surface ; when it cools up to 47.2 s, the center temperature is 281℃ and the whole specimen has almost achieved the martensitic transformation. The hardness value of the specimen gradual- ly decreases from the external surface to the center, which is very much in agreement with the performance of 18CrNiMo7 - 6 steel after thermal treatment.