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在变形温度280~400℃、应变速率0.001~1 s~(-1)、最大变形量50%的条件下,采用等温压缩实验研究了铸态镁合金AZ91D塑性变形和微观组织演变行为。结果表明:AZ91D热压缩变形中发生了不同程度的动态再结晶,提高变形温度和降低变形速率有利于促进动态再结晶晶粒的形核和长大,动态再结晶体积分数随真应变增大呈现慢-快-慢的增长规律。在对实验数据回归分析的基础上,建立了AZ91D动态再结晶临界条件、动力学方程和晶粒尺寸预测模型,并通过定量金相实验结果验证了该模型的合理性。
The plastic deformation and microstructure evolution of as-cast magnesium alloy AZ91D were studied by isothermal compression experiments under the conditions of deformation temperature of 280-400 ℃, strain rate of 0.001-1 s -1 and maximum deformation of 50%. The results show that dynamic recrystallization occurs in AZ91D during hot compression deformation. Increasing the deformation temperature and decreasing the deformation rate can promote the nucleation and growth of dynamic recrystallized grains. The dynamic recrystallization volume fraction appears with the increase of true strain Slow - fast - slow growth. Based on the regression analysis of the experimental data, the critical condition, kinetic equation and grain size prediction model of AZ91D dynamic recrystallization were established. The rationality of the model was verified by quantitative metallographic experimental results.