AZ31镁合金热压缩过程动态再结晶行为研究

Dynamic recrystallization behavior of AZ31 magnesium alloy during thermal compression

摘要:

通过AZ31镁合金热压缩实验,采用电子背散射衍射(EBSD)技术,对不同变形条件(不同温度、应变速率和变形程度)下镁合金热变形过程中的动态再结晶行为、晶粒取向和织构的产生等现象进行研究。结果表明,变形温度越高,再结晶程度表现的越充分,晶粒组织也越均匀,而变形程度越大或应变速率越小,再结晶程度则越大。在镁合金热变形过程中,变形温度是决定其动态再结晶机制的最大影响因素。300℃时,AZ31镁合金再结晶晶粒在原始晶界和亚晶界处形核,再结晶行为主要由亚晶界的转动形成,表现出典型的连续动态再结晶(CDRX)特征。400℃时,局部剪切变形时再结晶晶粒取向发生偏转,表现出典型的旋转动态再结晶(RDRX)特征。热压缩过程中产生{10-12}拉伸孪生,晶粒重新旋转基面取向形成基面垂直于压缩方向的纤维织构。

Abstract:

The dynamic recrystallization behavior, grain orientation and texture formation of magnesium alloy under different deformation conditions (temperature, strain rate and deformation degree) were studied by using electron backscattering diffraction (EBSD) in the thermal compression experiment of AZ31 magnesium alloy. The results show that the greater the deformation temperature, the more adequate the degree of recrystallization and the more uniform the grain structure. The greater the degree of deformation or the smaller the strain rate, the greater the degree of recrystallization. During the hot deformation of magnesium alloys, the deformation temperature is the biggest factor influencing the dynamic recrystallization mechanism. At 300℃, the recrystallized grains of AZ31 magnesium alloy nucleate at the original grain boundary and sub-grain boundary. The recrystallization behavior is mainly formed by the rotation of sub-grain boundary, which shows the typical continuous dynamic recrystallization (CDRX) characteristics. At 400°C, the orientation of the recrystallized grains is deflected during local shear deformation, showing the typical characteristics of rotational dynamic recrystallization (RDRX). During the thermal compression process, {10-12} tensile twins are generated, and the grains re-rotate the basal plane orientation to form a fiber texture with the basal plane perpendicular to the compression direction.