超(超)临界火电用新型奥氏体不锈钢的高温塑性变形行为及本构模型

Plastic deformation behavior and constitutive model of new austenitic stainless steel at high temperature used for ultra super critical power plant

利用Gleeble-3500热模拟试验机对新型奥氏体不锈钢CHDG-A进行单道次压缩试验,研究了该合金在950-1100℃和0.01-1 s^（-1）条件下的流变应力变化规律及变形组织演变规律。建立了新型奥氏体不锈钢CHDG-A的传统Arrhenius本构模型,耦合应变量后建立改进型本构模型,并引进相关系数R、平均相对误差δ评估改进型本构模型的预测精度。结果表明：在高温热变形过程中,新型奥氏体不锈钢CHDG-A的流变应力值受应变速率以及变形温度的影响显著,且动态再结晶更易在较低应变速率、较高变形温度条件下发生;应用改进型本构模型得到的流变应力预测值与试验值间的相关系数R为0.9944,而平均相对误差值δ仅为1.9952%,说明该本构模型能较好的预测新型奥氏体不锈钢CHDG-A的流变应力。

The change law of flow stress and evolution law of deformed microstructure at 950^（-1）100 ℃ and 0. 01-1 s^（-1） of new austenitic stainless steel CHDG-A were studied by Gleeble-3500 thermol-simulation machine. Traditional Arrhenius constitutive model of new austenitic stainless steel CHDG-A was established. And the modified constitutive model was built coupling with strain. The correlation coefficient R and average relative error δ were introdued to evaluate the accuracy of the modified constitutive model. Results show that the stress of new austenitic stainless steel CHDG-A is influenced by strain rate and deformation temperature significantly,and the dynamic recrystallization is more likely to occur at lower strain rate and higher temperature. The correlation coefficient R and average relative error δ between the predicted value of flow stress and the test value obtained by applying the modified constitutive model are 0. 9944 and 1. 9952%,respectively,which indicates that the constitutive model can accurately predict the flow stress of new austenitic stainless steel CHDG-A.