20MnNiMo钢热变形行为及基于物象的本构模型

Hot Deformation and a Physically-Based Constitutive Model for 20MnNiMo Steel

为研究20MnNiMo钢的热变形行为，在950～1250℃、0．01～10 S^-1的变形条件下对其进行高温热压缩实验，构建了20MnNiMo钢的包含动态回复和动态再结晶的两阶段本构模型．引入Zener—Hollomon参数，获得了变形工艺条件对模型中各参数的影响规律．结果表明：20MnNiMo钢的真应力一应变曲线具有明显的动态回复和动态再结晶现象，且随温度的升高或应变速率的减小，流变应力显著降低．对比分析实验值与模型预测值，可得相关系数及平均相对误差分别为0．9987和2．63％．

In order to investigate the hot deformation behavior of 20MnNiMo steel, the thermal compression tests were conducted at 950 to 1 250 ℃ and 0.01 to 10 s^-1. A two-stage constitutive model including dynamic recovery and dynamic recrystallization was developed. The response mechanisms of deformation conditions on the parameters of the model were obtained by introducing the Zener-Hollomon parameter. The results show that the true stress-strain curves have an obvious dynamic recovery and dynamic recrys- tallization phenomenon, and the flow stress decreases significantly with the increase of temperature or the decrease of strain rate. By comparing the predicted and experimented values, the correlation coefficient and mean absolute relative error are found to be 0. 998 7 and 2.63 %, respectively.