初始取向对AZ31镁合金微观织构演化的影响

来源期刊：金属学报2011年第2期

论文作者：吴新星 杨续跃 张雷 张之岭

文章页码：140 - 144

关键词：镁合金； 初始取向； 拉伸孪晶； 微观织构演化

Key words：Mg alloy； original orientation； tension twinning； microtexture evolution

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.

Abstract: 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^-3s^-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.