Investigation on the effect of pressure rate on formability of aluminum alloy during warm/hot sheet hydroforming

Warm/hot sheet bulging tests of 2A16-O aluminum alloy were conducted using elliptical bulging dies under various temperatures and pressure rates, in an effort to investigate the macroscopic and microscopic influence of the pressure rate on the formability and microstructural evolution of hydrobulging parts during warm/hot sheet hydroforming. The results revealed that the forming limit of the aluminum alloy was clearly influenced by the pressure rate as the temperature rose, wherein a lower pressure rate resulted in a higher forming limit. Metallographic observations and Energy Dispersive Spectrometer (EDS) analysis revealed no obvious influence of the pressure rate on the microstructure of hydrobulging parts after warm/hot sheet hydroforming. This study demonstrates that warm/hot sheet hydroforming of aluminum alloy may lead to an improved forming limit and inhibit microstructural degradation during processing.