( 1. 南京航空航天大学 机电工程学院, 南京 210016;
2. 北京航空材料研究院, 北京 100095)
摘 要: 在温度400～500 ℃、 初始应变速率为2.0×10-4 ～2.0×10-2 s-1的条件下， 对Al-6Mg-0.2Sc合金冷轧板材(初始晶粒尺寸为25 μm)进行了相应的超塑性能、 高应变速率超塑性胀形成形实验研究。 结果表明： 在450 ℃、 初始应变速率为2.0×10-2 s-1的实验条件下, Al-6Mg-0.2Sc合金冷轧板材具有高应变速率的超塑性能, 其最大延伸率为421%; 在高应变速率条件下, 胀形成形大端直径为d154 mm， 深度h为80 mm的锥形零件的成形时间为73 s, 成形后零件的壁厚变薄的不均匀率小于8%。 此外, 还对成形零件的微观组织进行了初步的SEM观察分析。 结果表明， 成形零件的微观组织无明显粗化， 其孔洞率小于1.5%。
关键字: Al-6Mg-0.2Sc合金; 高应变速率超塑性; 超塑性胀形; 微观组织
Al-6Mg-0.2Sc alloy
（ 1. College of Mechanical and Electrical Engineering,
Nanjing University of Aeronautics and Astronautics, Nanjing 210016, China;
2. Beijing Institute of Aeronautical Materials, Beijing 100095, China）
Abstract: The superplastic properties of a cold-rolled Al-6Mg-0.2Sc alloy were studied in the temperature range of 400-500 ℃ and strain rates range of 2.0 ×10-4-2.0×10-2 s-1 with a maximum elongation-to-failure of 308% recorded at 450 ℃ and an initial strain rate of 2.0×10-2 s-1. At the same time, high strain rate superplastic (HSRS) bulging of a cold-rolled Al-6Mg-0.2Sc alloy sheet was investigated at 450 ℃ and an initial strain rate of 2.0×10-2 s-1. The forming time of a cone-shaped part (diameter of 154 mm) is 73 s and nonuniformity of wall thickness is less than 8%. Besides, fracture microstructure of sample was examined using both optical and scan electron microscope. The results show that the grain is not coarsened and the cavity rate is less than 1.5%.
Key words: Al-6Mg-0.2Sc alloy; high strain rate superplasticity; superplastic bulging; microstructure
