铸态Mg-3Sn-1Mn-1La镁合金组织演变及本构方程建立

Libin Zhang1, 3, Guangming Liu1, 3*, Tingzhuang Han1, 3, Wenzhan Huang1, Rongjun Wang2, 3, Lifeng Ma2, 3

摘要:

通过对Mg-3Sn-1Mn-1La合金在200-450℃温度和0.001-1.0s-1应变速率范围内进行等温压缩，研究了铸态的Mg-3Sn-1Mn-1La合金的热变形行为和组织演变。流变应力随着变形温度的降低和应变率的增加而明显增加。再结晶晶粒尺寸随温度升高和应变速率降低而增加。在较低的变形温度下，连续动态再结晶是DRX的主要机理。随着变形温度的增加，不连续的动态再结晶成为主要再结晶机制。分析并校正了摩擦变形加热对流动应力的影响。结果表明，在较高的应变速率和较低的变形温度下，形变热对流动应力有显著的影响，而摩擦作用较小。根据实验结果，建立了应变补偿的Arrhenius型方程。将实验数据与计算出的流动应力进行对比，结果表明建立的本构方程可以充分描述实验合金的热变形行为。

关键词:Mg-Sn系镁合金，热变形，本构模型，动态再结晶

Abstract:

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 0.001-1.0s-1. The flow stress increases obviously with decreasing temperature and increasing strain rate. The recrystallized grain size increases with increasing temperature and decreasing strain rate. At lower deformation temperatures, continuous dynamic recrystallization is the main mechanism of DRX. However, discontinuous dynamic recrystallization becomes the predominant operating mechanism of DRX at high deformation temperature. 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 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.

Key words:Mg-Sn based alloy, hot deformation, constitutive equation, dynamic recrystallization