40 Cr钢喷雾淬火换热系数的计算及数值模拟

摘要

In order to calculate the heat transfer coefficient of 40Cr steel cylindrical specimen 25 mm in diameter by 100 mm long during fog quenching,the cooling curves during the fog quenching were measured by a four-channel sampling system,and the heat transfer coefficient was calculated by the nonlinear estimation method of inverse heat conduction method.The calculation results show that the fog quenching process has three stages such as film boiling stage,nucleate boiling stage and convective heat transfer stage,and that the heat transfer coefficient reached peak value of 9800 W·m-2·℃-1 when quenched to 120 ℃.Taking this heat transfer coefficient as a boundary condition,the fog quenching process of 40Cr steel was numerically simulated and,thereby,the temperature field, the structural field,the hardness field and the stress field at different moments of the quenching process were developed.%为计算25 mm ×100 mm 40Cr圆柱试件喷雾淬火冷却过程的换热系数，采用四通道采样系统测定了喷雾淬火过程的冷却曲线，并用反传热法中的非线性估算法计算出换热系数。计算结果表明，喷雾淬火过程分3个阶段：膜沸腾阶段、核沸腾阶段和对流换热阶段，并在冷却到120℃时，换热系数达到峰值9800 W·m-2·℃-1。采用此换热系数作边界条件，对40Cr钢的喷雾淬火过程进行了数值模拟，得到淬火过程中不同时刻的温度场、组织场、硬度场和应力场。