高温终轧工艺对初始织构不同的AZ31镁合金板材组织的影响

Effect of high temperature last rolling process on microstructure of AZ31 magnesium alloy sheets with different initial textures

以初始织构不同的AZ31镁合金板材为研究对象进行了高温终轧和最终退火,结合转靶X射线衍射仪和电子背散射衍射分析手段分析了不同板材基面织构的变化情况以及滑移和孪生对形变织构的影响规律。结果表明,高温终轧后,两种板材的宏观织构存在着单峰和倾斜的双峰基面织构区别;最终退火后,两种板材的织构强度都得到弱化,但弱化程度存在差异,并且再结晶织构在一定程度上遗传了形变织构的特征。对于初始织构强度较高的板材,高温终轧时锥面滑移活性增强,柱面滑移受到抑制,从而表现出带状变形集中区域,以此来弥补由于位错滑移受限引起的变形能力不足,此时形变织构的变化主要受到滑移和孪生的共同作用的影响。对于初始织构强度较弱的板材,高温终轧时非基面滑移活性得到增强,滑移和孪生相互竞争,孪生活动受到了明显抑制,此时形变织构的变化主要受到滑移的影响。

The AZ31 magnesium alloy sheets with different initial textures were taken as the research objects to carry out the high temperature last rolling and final annealing.The changes of basal texture of different sheets and the effect of twinning and slip on deformation texture were analyzed by means of X-ray diffractometer(XRD)and electron back scattering diffraction(EBSD)analysis.The results show that there exists the difference of single peak and inclined double peak basal texture in the macroscopic texture of the two kinds of sheets after the high temperature last rolling.The texture strength of the two kinds of sheets is weakened after final annealing,but the weakening degree is different,and the recrystallization texture inherits the characteristics of deformation texture to a certain extent.For the sheets with higher initial texture strength,the pyramidal slip activity increases and the cylinder slip is inhibited during high temperature last rolling,which results in the concentration zone of banded deformation to make up for the insufficient deformation capacity caused by the limited dislocation slip.At this time,the change of deformation texture is mainly affected by the joint effect of slip and twinning.For the sheets with weaker initial texture strength,the slip activity of non-base surface increases during high temperature last rolling,the slip and twinning compete with each other,and the twinning activity is inhibited obviously.At this time,the change of deformation texture is mainly affected by slip.