CONSTITUTIVE RELATIONSHIP OF HOT DEFORMATION OF AZ91 MAGNESIUM ALLOY

Hot compression deformation of AZ91 magnesium alloy has been performed on Gleeble-1500 under conditions of strain rates of 0.001-1 s(-1) and deformation temperatures of 250400 degrees C, and the flow stresses in different deformation conditions are investigated. The results show that the flow stress is significantly affected by both deformation temperature and strain rate; the flow stress decreases with the deformation temperature increasing and strain rate decreasing. The flow stress tends to be constant after a peak value at deformation temperature higher than 400 degrees C and strain rates less than 0.001 s(-1). The relations of the deformation activation energy and stress exponent with strain were obtained using the hyperbolic-sine mathematics model; and the hot deformation constitutive relationship was established. Comparing with experimental results; it is proved that the model reflects the real deformation feature of the AZ91 alloy.