一种铁镍铬合金的热变形行为及其本构模型的修正

Hot deformation behavior of a Fe-Cr-Ni alloy and the correction of constitutive model

在Gleeble3500热力模拟试验机上对800H合金进行高温单道次压缩实验,结合OM和TEM等表征手段,研究了该合金在变形温度1 000~1 150℃和应变速率0.01~1s-1条件下的热变形行为。结果表明,动态再结晶行为更易发生在较低应变速率和高变形温度条件下,变形过程中动态再结晶形核机制主要包含晶粒碎化、晶界迁移及亚结构合并;考虑应变量因素,建立应变量耦合的双曲正弦本构方程,利用此模型预测合金的流变应力。本构模型预测值与实验测得值之间的线性关系达至0.99648,且平均相对误差仅2.019%,说明这种应变量耦合型本构方程能较好的预测800H合金在实验条件内的流变应力。

Hot compression tests of alloy 800H were carried out at deformation temperatures of 1 000-1 150 ℃and strain rates of 0.01-1 s-1 by Gleeble-3500 thermo-mechanical simulator.The evolution of microstructure were analyzed combined with the technique of OM,SEM and TEM.The experimental result shows that the dy-namic recrystallization （DRX）is more likely to occur at a low strain and high temperature,the DRX nucleation mechanisms of alloy 800 H mainly include grain fragmentation,grain boundary and substructure coalescence;a developed hyperbolic sine equation was established which take into account the effect of strain on constitutive e-quation,then the accuracy of the constitutive equation was verified.Compared with experimental results,the correlation coefficient and average relative error of predicted and measured values are 0.99648 and 2.019%,re-spectively,indicating that the developed equations can give an accurate estimate of the flow stress for alloy 800H.