| Al-Mg-Sc alloy has high strength, corrosion-resistance, very good welding property, especial superplasticity. In the auto and aerospace industry, there is increasing interest in fabricating complex part by superplastic forming process. The alloy exhibits small elongation on normal temperature and is hard to deform. While on superplastic condition it has large elongation and its superplasticity is a research focus.It is a subject for Beijing Aero Material Institute. In this thesis superplasticity and bulging process are researched on Al-6Mg-0.2Sc alloy. Firstly uniaxial tensile tests were carried out on dog bone specimen of the alloy. At 450℃, it exhibits more than 300% of elongation prior to fracture under const strain rate of 2×10-3s-1. Then the bulging model of hemisphere and rectangular box were built and simulated on const strain forming to research the thickness distribution. A pressure-time curve was gotten through the simulation by using the software MARC. The results of experiment which followed the curve agreed well with that of the simulation.The non-uniform thickness distribution and cavity have negative influence on the formability. Direct-reverse superplastic bulging can improve the thickness distribution greatly. The simulation of hemisphere bulging shows that the thin rate decreases about 10% with direct-reverse process. Cavity rate is decreased evidently in the bulging if back pressure is provided. Experiment shows that proper back pressure can eliminate big cavity on the condition that strain is not very high.
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