In this paper, the subject of research is the AZ31B magnesium alloy. Aiming at the poor formability of magnesium alloys at room temperature, we have introduced isothermal local loading technology to improve the formability of magnesium alloys. We combined finite element simulations and experiments to study the effects of forming parameters on the forming limit angle and thinning rate of single-point incremental forming under isothermal local loading. The conclusions were further validated by changes in grain size in micrographs. The results showed that the forming limit angle of the AZ31B magnesium alloy sheet increased as the forming temperature increased. Maximum thinning first decreased and then increased, reaching the lowest point at 250 °C. At 250 °C, the grain size is large and evenly distributed, which is the best forming temperature. The radius of the tool head increases, the forming limit angle increases, the maximum thinning rate decreases, and the overall change of the average grain size is relatively small. However, the grain size is more uniform when the radius is 5 mm, and 5 mm is the best tool radius. The feed rate is inversely proportional to the forming limit angle and directly proportional to the maximum thinning rate. Different feed rates have different degrees of compression and elongation of the grains. The forming quality is better when the feed rate is 2 mm. The initial plate thickness is proportional to the limit angle, the maximum thinning rate, and grain size. And 1 mm is the best plate thickness to ensure the forming quality. This paper is important for developing the forming theory of isothermal local loading that can improve the high-performance forming of alloy parts in advanced manufacturing.

本文的研究对象是AZ31B镁合金。针对镁合金常温成形性较差的问题，我们引入了等温局部加载技术，以提高镁合金的成形性。我们结合有限元模拟和实验研究了成形参数对等温局部加载下单点渐进成形成形极限角和减薄率的影响。通过显微照片中晶粒尺寸的变化进一步验证了该结论。结果表明，AZ31B镁合金薄板的成形极限角随着成形温度的升高而增大。最大变薄先减小后增大，在 250 °C 时达到最低点。250℃时晶粒大且分布均匀，为最佳成型温度。刀头半径增大，成形极限角增大，最大减薄率减小，平均晶粒度整体变化较小。但半径为5mm时晶粒尺寸更均匀，5mm为最佳刀具半径。进给速度与成形极限角成反比，与最大减薄速度成正比。不同的进料速度对晶粒的压缩和伸长程度不同。进给量为2mm时成型质量较好。初始板厚与极限角、最大减薄率和晶粒尺寸成正比。而1mm是保证成型质量的最佳板厚。