Fe-15Cr-27Ni-4Al-2Mo-0.6Nb奥氏体耐热钢的热变形行为

Hot deformation behavior of Fe-15Cr-27Ni-4Al-2Mo-0.6Nb austenitic heat-resistant steel

利用Gleeble-3800型热-力模拟试验机对一种新型含铝奥氏体耐热钢Fe-15Cr-27Ni-4Al-2Mo-0.6Nb进行了单道次热压缩实验,研究了其在900~1200℃和0.001~10 s^(-1)条件下的热变形行为,并观察了变形后的微观组织。通过五次多项式拟合,建立了考虑应变量的改进型本构模型,并对其准确性进行了验证。结果表明:在热变形过程中,材料的流变应力与变形温度负相关,且温度越低,应力增加越明显;而流变应力与应变速率之间的关系则是正相关。动态再结晶体积分数随变形温度的升高而逐渐增大。用改进型本构模型计算所得的流变应力值与实验所得的流变应力值吻合较好。预测值与实验值的相关系数为0.99076,平均相对误差为6.68%,说明采用该模型预测新型含铝奥氏体耐热钢的流变行为具有较高的可靠性。

A single pass hot compression experiment of a new alumina-forming austenitic(AFA)heat-resistant steel Fe-15Cr-27Ni-4Al-2Mo-0.6Nb was carried out by Gleeble-3800 thermal-mechanical simulation test machine.The hot deformation behavior of the alloy under the conditions of 900-1200℃and 0.001-10 s^(-1) was studied,and the microstructure after deformation was observed.Through fifth order polynomial fitting,an improved constitutive model considering the strain was established,and its accuracy was verified.The results show that the flow stress of material is negatively correlated with the deformation temperature during the hot deformation process,and the lower the temperature is,the more obvious the increase of stress is,while the relationship between the flow stress and the strain rate is positive.The volume fraction of dynamic recrystallization gradually increases with the increase of deformation temperature.The flow stress values calculated by the improved constitutive model are in good agreement with the experimental values of flow stress.The correlation coefficient between the predicted values and the experimental values is 0.99076,and the average relative error is 6.68%,which indicates that using this model to predict the flow behavior of the new type AFA heat-resistant steel has high reliability.