Superplastic Deformation Behavior of 7B04 Al Alloy

The superplastic tensile tests were carried out for 7B04 Al alloy under a temperature range of 470-530℃ at a strain rate range of 0.0003-0.01s-1. Then,the superplastic deformation behavior and deformation mechanism of the material were investigated. The results show that with the increase of temperature and decrease of strain rate, the flow stress of 7B04 Al alloy is decreased and the elongation is increased.When the deformation temperature is at 530℃ and the strain rate is 0.0003s-1, the elongation reaches the maximum value of 1105%, which indicates that at this process parameter the optimal superplasticity is obtained; the strain rate sensitivity index m value is above 0.3 and increases as the temperature going up; when the deformation temperature is at the range of 500-530℃, the m value is above 0.5,the superplastic deformation mechanism of 7B04 Al alloy predominated by grain boundary sliding; the superplastic deformation activation energy Q value is 190kJ/mol which indicates that the superplastic deformation is significantly controlled by the intercrystalline diffusion; the liquid phase will be produced along the grain boundaries of 7B04 Al alloy during superplastic deformation,which can enhance the superplasticity with a moderate amount.