Effects of melt-treatment and hot deformation on the behavior of elevated flow stress of Al sheets for pressure can （or called Al piece） during plastic deformation were investigated by hot-simulation testing method.The results show that Al pieces prepared by different melt-treatment all possess the remarkable characteristics of steady flow stress.The flow curves show stress peak with the strain rate of 10 s

-1

meaning the occurrence of the dynamic recrystallization.A hyperbolic sine relationship is found to correlate well the flow stress with the strain rate

and an Arrhenius relationship with the temperature.For the high-efficient melt-treatment Al pieces

the values of true stress and true strain in the steady deformation are less than that of no-or conventional melt-treatment Al pieces

and its hot deformation activitation energy is remarkably decreased.In addition

the flow stress equation at elevated temperature of the Al pieces was derived also.