通过20MnNiMo钢多组试样的热压缩实验获得应变速率为0．01～10s^-1、变形温度为1173～1473K条件下的真应力-应变数据。结合Arrhenius双曲正弦本构方程，通过线性回归分析求解得到不同变形条件下本构模型中的热变形激活能Q，材料常数n、a及结构因子A，从而构建了用于表征20MnNiMo钢流变应力与应变量、温度、应变速率之间内在关系的本构方程。研究结果表明：20MnNiMo钢在热压缩变形过程中发生了明显的动态软化行为，流变应力水平随应变速率的增加而增加，随温度的升高而降低；流变应力的预测值与实验值较吻合，而且预测的最大相对误差仅为7．54％。
A series of billet samples of 20MnNiMo alloy were compressed on a Gleeble-1500 thermal simulator in the range of temperatures from 1173 to 1473 K and strain rates of 0. 01 - 10 s^-1, meanwhile true stress-strain data were collected. By multiple linear regression for hyperbolic sine equation in Arrhenius type, deformation activation energy Q, materials constants n, a and structural factor A under different deforming conditions were obtained, and then the constitutive equation of as-annealed 20MnNiMo steel for description of the relationships among flow stress, strain, strain rate and temperature was constructed. The results show that dynamic softening behaviors occurs obviously during the hot compressions of as-annealed 20MnNiMo alloy. The flow stress level increases with increasing strains rate, and decreases with increasing temperature. The flow stress predicated by the proposed model agrees well with experimental results, and the maximum relative error is only 7.45%.
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