AZ31镁合金变路径压缩过程中解孪晶行为分析

Untwinning Behavior of AZ31 Mg Alloy during Multi-path Compressions

对AZ31镁合金轧制板材进行RD-ND-RD-ND(RD-rolling direction,轧向;ND-normal direction,法向)的变路径压缩实验,研究了变形过程中的力学性能,并采用EBSD技术跟踪了上述变形过程中晶粒取向变化,分析了孪晶变体的启动情况。结果表明,在变路径压缩过程中,依次对应{10 12}拉伸孪晶-{10 12}解孪晶-{10 12}拉伸孪晶-{10 12}解孪晶的微观变形机制。首次解孪晶使屈服强度下降明显,而后续的孪晶和解孪晶过程的屈服强度都增加,且两者差值很小。解孪晶过程中孪晶变体的启动遵循Schmid定律,但出现明显的选择性,解孪晶过程都由t3或t4变体完成。

The multi-paths compression with sequential RD〉ND〉RD〉ND（RD-Rolling Direction;ND-Normal Direction） was performed on the AZ31 magnesium alloy rolled sheet, and mechanical property of the previous deformation were studied, the electron backscatter diffraction （EBSD） technique was applied to track the grain orientation evolution during the above deformation, and activations of twin variants were analyzed. The results show that the deformation mechanism of {10-12} tensile twin -〉{10-12} untwin -〉{10-12} tensile twin and {10-12} untwin are sequentially related to each compression during the above deformation. The yielding strength was significantly decreased during the first untwining, but the yielding strengths were increased for both twinning and untwining during the following deformations, and there are not obvious differences between them. The activation of untwinning follows the Schmid criterion, and there is an obvious selective tendency for twin variant activation, twin variant t3 or t4 were activated to start the untwinning.