Superplastic blow forming of 2219 aluminium alloy

Superplasticity in 2219 aluminum alloy was achieved through thermomechanical processing. Tension tests showed that the alloy exhibits superplastic behavior in the temperature range of 450-540°C and strain rates ranging from 2.2×l0^-5 to 1.1×10^-1 s ^-1. A maximum elongation-to-failure of 670% was recorded at 500°C and at the initial strain rate of 2.2×10^-4 s^-1. High cavitation level and intensive grain growth were observed. Sheet of the 2219 aluminum alloy was blow formed into conical shape using two different methods: simple negative and backpressure forming. A strain of 2.1 was obtained at 500°C under the backpressure blow forming condition. It was found that elongation to failure under blow forming with backpressure is about 1.5 times higher than that under a simple female forming. Microstructural evolution of blow formed parts was also examined.