将从挤压棒材中截取的长轴与挤压方向分别成0o, 45o和90o的AZ31镁合金长方体试样在中、高温度(523-723 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0o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45o和 90o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0o试样出现急剧加工硬化的原因. 0$^{\circ}$试样变形至 ε=0.2时几乎所有的晶粒都发生了近90o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, 45o试样只是在大应变时才发生晶粒的缓慢转动, 而90o试样则几乎不发生晶粒转动.
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 0o, 45o and 90o 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 0o 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 45o or 90o samples was lower than 10%. The initial texture in the 90o sample scarcely changes and the relative intensity decreased with increasing strain.
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