超超临界火电用奥氏体耐热钢的热变形行为

Hot deformation behavior of austenitic heat resistant steel for ultra-supercritical thermal power

利用Gleeble-3500热力模拟试验机研究了奥氏体耐热钢Super304H在变形参数950~1100℃、0.01~1s^-1条件下的热加工性能。根据流变应力曲线,推导出Super304H奥氏体耐热钢的Arrhenius型本构模型并构建了耦合应变量因素的改进型本构模型。基于动态材料模型(DMM)构建了Super304H的热加工图,给出材料的建议热加工参数区间。结果表明:较低应变速率、较高温度对应的流变应力值较小,流变应力曲线的动态再结晶特征也更为明显。依据所构建的本构模型,得到材料在实验参数条件下的流变应力预测值与实验值的相关系数R为0.99306,平均相对误差δ为3.046%,说明所构建耦合应变量因素的本构模型具有良好的预测能力。Super304H奥氏体耐热钢的可加工区间为:1060~1100℃、0.01~1.8s^-1。

Hot deformation behaviors of Super304H austenitic heat resistant steel in temperature range of 950-1100℃ and strain rate range of 0.01-1s^-1 were studied by Gleeble -3500thermal -mechanical simulator.Based on the flow stress curves of the steel,the Arrhenius constitutive model of the Super304H austenitic heat resistant steel was derived and the improved constitutive model coupling the strain factor was constructed.The hot processing map based on the dynamic material model (DMM)showed the proposed hot processing parameter range of the anstenitic heat resistant steel.The results show that the flow stress decreases with the increase of temperature and strain rate.The flow stress curve under lower strain rate and higher temperature exhibits obvious DRX -type characteristics.Based on the construoted constitutive model,the correlation coefficient R between the predicted value of the flow stress and the experimental value was 0.99306,and the average relative error δ is 3.046%.It shows that the constitutive model coupling the strain factor has good predictive ability.The proposed hot processing range of the Super304H is 1060-1100℃,0.01-1.8s^-1.