The hot compression test was carried out to investigate the deformation behaviors of as-cast AZ91 D magnesium alloy.According to the experimental results

the hot processing maps of the AZ91 D atε=0.4 andε=0.6 were established based on dynamic material model（DMM）theory.The results reveal that the flow stress is decreased with the increase of temperature or the decrease of strain rate.The flow stress curves exhibit the characteristics of strain softening obviously.Hot working instability region of AZ91 Dalloy exhibits the increasing tendency with increasing in deformation rate.At high temperature and high strain instability region

deformation instability is controlled by the adiabatic shear band and crack

while at low temperature and high strain instability region

un-even deformation and flow instability are attributed to the formation of partial shearing band at un-even dynamic recrystalization fine area.