Casting-forging combination forming process is an advanced manufacturing technique which is applicable to manufacture the parts with both complex shape and high performance. As a fundamental research of casting-forging combination forming process, as-cast 40CrNiMo alloy steel is obtained through vacuum casting by using metal mold. The isothermal compression tests of as-cast 40CrNiMo alloy steel are implemented on a Gleeble-3800 thermal simulation machine at deformation temperatures of 800, 900, 1000 and 1100 ℃, with strain rates of 0.001, 0.01, 0.1, 1 and 10 s⁻¹. The results indicate that the true stress-strain curves present typical dynamic recovery type under low deformation temperature and high strain rate. With the increases of deformation temperature or the decreases of strain rate, the true stress-strain curves gradually transform to dynamic recrystallization type. The Arrhenius-type constitutive equation with Zener–Hollomon parameter is determined for constitutive analysis. The kinetic model and kinematic model of dynamic recrystallization are deduced to describe the dynamic recrystallization behavior.

铸锻结合成型工艺是一种先进的制造技术，适用于制造形状复杂，性能高的零件。作为铸锻结合成形工艺的基础研究，采用金属模具通过真空铸造得到铸态40CrNiMo合金钢。在Gleeble-3800热模拟机上对铸态40CrNiMo合金钢进行等温压缩试验，其变形温度为800、900、1000和1100℃，应变速率为0.001、0.01、0.1、1和10 s ^-1。结果表明，在低变形温度和高应变速率下，真实的应力-应变曲线呈现典型的动态恢复类型。随着变形温度的升高或应变率的降低，真实的应力-应变曲线逐渐转变为动态再结晶类型。确定具有Zener–Hollomon参数的Arrhenius型本构方程用于本构分析。推导了动态再结晶动力学模型和运动学模型来描述动态再结晶行为。