在钢高压气体淬火过程的计算模拟中，关键键问题之一是温度场和应力场边界条件的确定。本文利用显示有限差分法、非线性估计法和由热电偶测试而得到的温度一时间关系，求解热传导方程的逆问题，得出了气体淬火过程表面换热系数与温度间的非线性关系。这种方法具有收敛速度快、不受试件表面加T质量限制，而且利用了热电偶温度检测技术较为成熟稳定的特点。

通过对9SiCr合金刃具钢在清水、锭子油和高压气体等淬火介质中淬火对比实验，研究了9SiCr合金刃具钢在不同介质淬火工艺处理后的性能。研究结果表明，水淬火时试件表面与中心的温差较大，锭子油次之，高压气体较小；试件高压气体淬火时，温度梯度小，整个断面冷却比较均匀，可以预计，相应的热应力和热变形也比较小；应用适当压力的氮气能够实现淬透性比较好的9SiCr合金刃具钢的淬火处理。

In order to simulate thermal strains, thermal stresses, residual stresses and microstructure of the steel during gas quenching by means of the numerical method, it is necessary to obtain an accurate boundary condition of temperature field, The surface heat transfer coefficient is a key parameter. The explicit finite difference method, nonlinear estimation method and the experimental relation between temperature and time during gas quenching have been used to solve the inverse problem of heat conduction. The relationship between surface temperature and surface heat transfer coefficient of a cylinder has been given. The nonlinear surface heat transfer coefficients include the coupled efFects between martensitic phase transformation and temperature.

In numerical simulation of quenching process, the boundary conditions of temperature field and stress field are very important, in which the boundary conditions of temperature field are very complicated. In order to simulate the thermal strains, thermal stresses, residual stresses and microstructure of the steel during gas quenching by means of the numerical method, it is necessary to obtain an accurate boundary condition of temperature field. The surface heattransfer coefficient is a key parameter. The explicit finite difference method, non-linear estimate method and the experimental relation between temperature and time during quenching have been used to solve the inverse problem of heat conduction. The relationships between surface temperature and surface heat-transfer coefficient of cylinder have been given. The non-linear surface heat-transfer coefficients include the coupled effects between phase transformation and temperature. In calculation, physical properties were treated as the function of temperature and volume fraction of constituent. The results obtained have been shown that this technique can determine effectual the surface heat-transfer coefficients during gas quenching.

用实验和数值计算相结合的方法，得到半圆柱壳体快速冷却过程中内外表面的非线性表面换热系数。在此基础上，用有限单元法对半圆柱壳体的热应力和变形进行了分析。在数值计算中，模拟钢的CCT图，计算了奥氏体、珠光体、贝氏体和马氏体的体积百分比，并将热物理性质和力学性能处理为相变体积百分比和温度的函数。所得结果表明，在半圆柱壳体快速冷却过程中的热应力和变形计算中，有必要考虑非线性表面换热系数、相变等非线性效应。