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通过对铸态Mg-3Sn-1Mn-1La合金在变形温度为200～450℃、应变速率为0.001～1.0s-1条件下进行热压缩实验,研究了其热变形行为和微观组织变化规律.结果表明:随着变形温度的降低和应变速率的升高,流变应力明显增大而再结晶晶粒尺寸减小.在变形温度较低的条件下,连续动态再结晶是主要的再结晶机制.然而,当变形温度升高时,非连续动态再结晶机制占主导.分析和修正了摩擦和变形热对流变应力的影响.结果表明,与摩擦相比变形热对流变应力的影响更加明显,且随着应变速率的增加和变形温度的降低,变形热对流变应力的影响更加明显.在实验数据的基础上建立了应变修正的本构方程.通过对实验值与预测值的对比发现,所建立的本构方程能够准确地描述实验合金的热变形行为.“,”Hot deformation behavior and microstructural evolution of the as-cast Mg-3Sn-1Mn-1La alloy were investigated by isothermal compression at temperature of 200～450℃and strain rate of 0.001～1.0 s-1.The results show that the flow stress increases obviously with the decrease of the temperature and the increase of the strain rate.The recrystallized grain size increases with increasing the temperature and decreasing the strain rate.At lower deformation temperatures,many twins form to coordinate deformation and continuous dynamic recrystallization is the main mechanism.However,discontinuous dynamic recrystallization becomes the predominant operating mechanism of dynamic recrystallization at high deformation temperature.Plate-shaped MgSnLa compounds,which have a coherent relationship with the matrix,have a pinning effect on the α-Mg grain boundary.The effects of friction and deformation heating on flow stress were analyzed and corrected.The results show that deformation heating has a significant influence on the flow stress at higher strain rates and lower temperatures,while the influence of frictional effect is slight.Based on the experimental results,a strain-compensated Arrhenius-type equation was developed.Comparison of the experimental data with the calculated flow stress indicates that the developed constitutive equations can adequately describe the hot deformation behavior of the experimental alloy.