中文摘要：

将从挤压棒材中截取的长轴与挤压方向分别成0°,45°和90°的AZ31镁合金长方体试样在中、高温度（523723 K）下沿长轴方向压缩变形,利用OM和SEM/EBSD技术观察和分析了初始取向对其微观织构演化的影响.结果表明,随着变形温度的降低,初始取向对变形行为的影响显著增加,在523 K时,长轴平行挤压方向的0°试样在ε=0.06时拉伸孪晶体积分数可达30%,随着应变量的增加,孪晶体积分数持续增加,在ε=0.3时达到90%;沿与棒材长轴夹角45°和90°截取的试样在ε=0.3时孪晶不足10%;拉伸孪晶的大量存在是0°试样出现急剧加工硬化的原因.0°试样变形至ε=0.2时几乎所有的晶粒都发牛了近90°的转动,基面由变形前平行于压缩方向转至与压缩方向垂直,45°试样只是在大应变时才发生晶粒的缓慢转动,而90°试样则几乎不发生晶粒转动.

英文摘要：

The deformation behavior of AZ31 Mg alloy was studied in the temperature range from 523 to 723 K under a strain rate of 3×10^-3 s^-1. Cuboid samples with different orientations were machined from an extruded rod along angles of 0°, 45° and 90° to the extrusion direction, respectively. The effects of original orientation on microtexture evolution were analysed by OM and SEM/EBSD techniques. The results showed that the true stress true strain curves were sensitive to original orientation especially below 623 K. Extensive {1012} tension twins were formed at 523 K in the 0° samples and the volume fraction of twins increased rapidly to 90% at a strain of ε=0.3. Namely, the basal planes initially parallel to the compression axis rotated quickly by twinning to an orientation perpendicular to the compression axis. In contrast, the volume fraction of {1012} twinning in the 45° or 90° samples was lower than 10%. The initial texture in the 90° sample scarcely changes and the relative intensity decreased with increasing strain.