Influence of Pulsed Current on Superplasticity of Fine Grained 1420 Al-Li Alloy

The effects of an externally applied electropulse on the superplastic deformation behavior and microstructure of 1420 Al-Li alloy were studied. The flow stress of superplastic deformation was reduced by the high-density electropulse while the elongation was increased. The optimal electrical parameters for superplastic deformation were 192A/mm² of current density, 150Hz of frequency and 30s of duration at 480°C and 0.001s^-1. The elongation raised by 68% compared to that without electropulse. Furthermore, the grain was refined and the average grain size was reduced after superplastic deformation with the optimal electropulse. It is noted that the electropulse promoted the recrystallization and restrained the grain growth.