PREDICTED CONSTITUTIVE MODELING OF HOT DEFORMATION FOR AZ31 MAGNESIUM ALLOY

The uniaxial compression tests of AZ31 magnesium alloy at different strain rates of 0.01-10 s -1 and different deformation temperatures of 523-723 K were performed by using Gleeble-1500 simulator with a maximum strain of 0.916.The influences of deformation temperature and strain rate on the flow stress were investigated.The fine microstructure is attributed to dynamic recrystallization during compression process at 523 K.The stretched grains of dynamic recrystallization and growth up along radial direction were founded in microscopic observation at 723 K. Considering plasticity deformation and friction induced temperature rise, the flow stress was corrected at high strain rate by using temperature compensation.The peak flow stress and unified constitutive model were established based on hyperbolic sine model.Strain sensitivity of flow stress was studied to describe the coupling of materials parameters on the strain, and then the relationship between deformation temperature, strain rate and strain during hot deformation was obtained.Comparing with experimental results, the correlation coefficient and average relative error of predicted and measured values are 0.976 and 5.07% respectively, it is proved that the model reflects the real deformation feature of the AZ31 magnesium alloy.KEY WORDS AZ31 magnesium alloy, hot-compressive deformation, constitutive relationship, flow stress