强力旋压镁合金筒形件的显微组织及微纳力学性能

Microstructure and Micro/nano Mechanical Properties of Magnesium Alloy Tube by Power Spinning

以AZ31镁合金的强力旋压成形工艺为例,通过6道次旋压成形获得镁合金筒形件,对其各道次组织演变规律及筒坯的微纳力学性能进行了分析。原始筒坯壁厚为10mm经6道次强力旋压成形,获得了壁厚为1mm的成形良好、无鼓包等缺陷的镁合金筒形件;采用金相显微镜对各道次的筒坯试样的显微组织进行分析,结果表明:组织由原始粗大的、不均匀组织逐步转变为以孪晶为主、细小的均匀的组织;采用G200微纳力学测试系统对各道次的镁筒坯试样进行纳米压痕测试分析,结果表明:镁合金筒坯硬度随着旋压道次的增加而提高,原始镁合金筒坯硬度为0.377GPa,6道次旋压后镁合金筒坯的硬度为1.053GPa,提高约2.8倍,而旋压前后模量值保持基本不变;采用万能试验机对旋压成形的筒形件进行拉伸试验并对其断口进行SEM分析,结果表明:旋压前后的镁合金筒坯断口均呈现塑性断裂,但是原始镁合金断口中韧窝大而深,经多道次旋压后的断口中韧窝小而浅。

Taking AZ31 magnesium alloy as an example, a 6-pass power spinning process for magnesium alloy spun tubes was studied, and the microstructure evolution and the micro/nano mechanical properties of the tube billet were analyzed. The magnesium alloy tube with a wall thickness of 1 mm, which is well formed and has no bulging defects, was obtained by 6-pass power spinning forming from a billet with a wall thickness of 10 mm. The microstructure of the tube sample after each spinning pass was analyzed by optical microscope. The results show that the microstructure changes from a coarse and uneven initial structure to a fine and uniform structure dominated by twins. The nanoindention properties were tested by G200 Micro-nano mechanics test system. The results indicate that the hardness of the magnesium alloy tube billet increases with the spinning pass increasing, which of the original and the spun tube after 6 passes are 0.377 GPa and 1.053 GPa, respectively. The elastic modulus of the tube samples remains unchanged before and after power spinning. According to the tension test and SEM analysis, the tube samples exhibit plastic fracture characteristics before and after power spinning. However, the dimples of the original magnesium alloy fracture are large and deep, while they become small and shallow after the power spinning.