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在温度为220~380℃和应变速率为0.001~1s~(-1)的条件下进行等温热压缩,研究铸态AZ91D镁合金的变形行为和动态再结晶行为。讨论变形温度和应变速率对动态再结晶行为的影响。结果表明,动态再结晶晶粒的形核和长大极易在高温和低应变速率的条件下发生。为预测动态再结晶的演变过程,在真实应力—应变曲线数据的基础上,提出AZ91D镁合金的动态再结晶动力学模型。该模型揭示动态再结晶的体积分数随着真实应变的增加而增加,其增长趋势呈典型的“S”曲线。通过对比发现由动力学模型所预测的结果和微观组织观测的数据具有很好的一致性,验证了所建立的AZ91D镁合金动态再结晶动力学模型的准确性。
The deformation behavior and dynamic recrystallization behavior of as-cast AZ91D magnesium alloy were studied under isothermal hot compression at the temperature of 220 ~ 380 ℃ and the strain rate of 0.001 ~ 1s ~ (-1). The effects of deformation temperature and strain rate on the dynamic recrystallization behavior were discussed. The results show that the dynamic recrystallization grain nucleation and growth easily occur at high temperature and low strain rate conditions. In order to predict the evolution of dynamic recrystallization, a kinetic recrystallization kinetic model of AZ91D magnesium alloy was proposed based on the real stress-strain curve data. The model reveals that the volume fraction of dynamic recrystallization increases with the increase of real strain, and its growth trend is typical “S” curve. By comparing the results predicted by the kinetic model with the data from the microstructure observation, there is a good agreement, which verifies the accuracy of the kinetic recrystallization model of the AZ91D magnesium alloy.