等通道弯曲路径对AZ31镁合金薄板组织和性能的影响

Effect of Equal Channel Angular Bending on Microstructure and Properties of AZ31 Magnesium Alloy Sheet

摘要:

本研究在150 ℃下对AZ31镁合金轧制薄板（2 mm）进行不同路径的等通道弯曲变形实验。系统对比研究5道次同一路径、绕法向旋转路径及绕轧向旋转路径下等通道弯曲变形板材微观组织及力学性能演变。结果表明：经过5道次等通道弯曲变形后，板材内部引入了大量拉伸孪晶（ETW）以及一定量的压缩孪晶（CTW）和二次孪晶（DTW），能够有效改善基面织构，经过退火处理后，镁合金薄板材的延伸率都有明显提升。特别地，绕轧向旋转5道次等通道弯曲变形后，板材中ETW面积占比可达28.74%，退火后板材的断裂延伸率达到28.8%，抗拉强度为235.7 MPa。相比初始板材，断裂延伸率相对提升率为57.4%，而抗拉强度仅下降了3.8%。

Abstract:

The equal channel angular bending (ECAB) of AZ31 magnesium alloy rolled sheet (2 mm) under different paths was conducted at 150 ℃. The evolutions of microstructure and mechanical properties of the sheet were investigated after 5-pass ECAB along the same path, normal direction rotation path and rolling direction (RD) rotation path. The results show that after 5-pass ECAB, a large amount of extension twinning (ETW) and a certain amount of contraction twinning (CTW) and double twinning (DTW) are introduced into the sheet, which can effectively improve the basal texture of the base plane. After annealing treatment, the elongation of the sheets undergone ECAB is obviously improved. In particular, the area fraction of ETW in the deformed sheet rotated 5 passes around the rolling direction (RD) can reach 28.74%, and after annealing, the elongation can reach 28.8% with a tensile strength of 235.7 MPa. Compared with the original sheet, the relative increase ratio of the elongation is 57.4%, while the tensile strength is only 3.8% lower.