AZ31镁合金薄板经不同累积应变的连续弯曲变形后的显微组织与成形性能

对AZ31镁合金板材进行不同累积应变的连续弯曲变形及退火处理,随后对显微组织与力学性能的变化进行了研究。结果表明:经不同累积应变的连续弯曲变形后,镁合金板材的显微组织中没有发现孪晶,退火后,板材表层的晶粒异常长大,粗晶层的厚度随着累积应变的增加而增加,并且镁合金板材的织构朝RD方向偏转,偏转角度随累积应变的增加而增大;与原始板材相比,连续弯曲变形及退火处理使镁合金板材呈现出较好的室温成形性能(杯突值由2.3 mm提高到4.9 mm,提高了~113%),这主要归因于基面织构的改善使镁合金板材的r值减小与n值增大。

Evolution of microstructure and formability of AZ31 Mg alloy sheets processed by continuous bending with different accumulated strain

AZ31 alloy sheets were subjected to continuous bending (CB) process with various accumulated strain in a single pass at room temperature, and followed by annealing treatment. The corresponding microstructure and mechanical properties of as-received and CB sheets were investigated in the present paper. The obtained results indicated that no twins were observed in all microstructures during CB process. Abnormal grain growth occurred in the surface part after annealing and the depth of coarse-grained layer increased with the accumulated strain increasing. Moreover, the CB sheets in annealing condition exhibited a RD-tilt basal texture, and the inclination angle increased with the accumulated strain increasing. Compared to the as-received sample with a strong basal texture, the CB processed samples exhibited better stretch formability (2.3mm vs. 4.9mm, increased by ~113%), due to smaller r-value and larger n-value, which was related to the texture evolution.