20CrMnTiH本构模型的建立及验证

以高温压缩实验为基础，分析了变形温度1 123~1 423 K、应变速率0.01~10 s-1条件下20CrMnTiH的流动应力行为，并引入Zener-Hollomon参数，根据蠕变理论回归确定变形激活能、硬化指数、材料相关常数，构建了材料的本构模型.以Z参数作为本构模型准确性的衡量标准，根据Arrhenius指数方程建立了峰值应力、峰值应变关于Z参数的表达式并求出估算值，代入基于应变软化的应力应变方程，采用整个应变区间上的非线性拟合求解待定参数.方程计算值与实验数据具有良好一致性，平均误差为6.84%，证明Z参数的精度较好，从而间接验证了该模型的准确性.

A Constitutive Model of 20CrMnTiH Steel and Its Validation

Based on high temperature compression tests, the flow stress behavior of 20CrMnTiH under the condition of the deformation temperature of 1 123~1 423 K and strain rate of 0.01~10 s-1 was analyzed. The activation energy Q, the stress component n and the material constant α and A were determined by the linear regression method, while Zener-Hollomon parameter was introduced. Then the constitutive model was created according to the creep theory. For model verification, the Z parameter was set as a measurement. The expressions of peak stress and peak strain were then set up with Arrhenius formula, of which the calculated values were brought into the formula based on strain softening exponent. The relationship between stress and strain was derived by nonlinear curve fitting in the whole strain range. The calculated values and the experimental data were in good agreement with a mean error of 6.84%, which verified the accuracy of the Z parameter and the constitutive model.