Az31 Magnesium Alloy During Hot Deformation Behavior Study And Numerical Simulation

In this study, the Gleeble-1500D thermal simulator was used to the isothermal compression tests of AZ31 magnesium alloy. The flow stress curve of magnesium alloy was analyzed, and then established flow stress constitutive equations of AZ31 magnesium alloy. The microstructures under different deformation were examined by XRD and optical microscope. The influences of dynamic recrystallization processes by deformation factors such as temperature, strain rate and strain was analyzed. The stress-strain curve of AZ31 magnesium alloy was gained through Gleeble-1500D simulator. The Equal Channel Angular Extrusion process of AZ31 magnesium alloys was simulated by DEFORM-3D software. The influence on ECAE by internal fillet radius was analyzed. The results are as follows:1. The flow stress curves of AZ31 magnesium have dynamic recrystallization character under different deformation conditions. The peak stress and strain change with changing the temperature and strain rate. When the temperature rises to 573K, peak stress decreases obviously. So the hot working temperature of AZ31 magnesium alloy should be more than 573K.It is shown that the flow stress behavior of AZ31 magnesium alloy is described more exactly by power exponent model. Through regression ductility enhancement in AZ31 magnesium alloy of power exponent model and parameters of the power exponent function Z:2. There are no Mg17Al12 precipitates in the hot compress process of AZ31 magnesium alloy by XRD analysis. The {1010} and {1120} crystal face are parallel to cross section of sample in the compression. When the temperature is below 573K, the deformed microstructure basically consists of shear bands and twins. At 623K the microstructure consists of recrystallized grains, the alloy entirely shows the typical characteristics of the necklace-shaped microstructure. When the strain rate is 1 s^-1, there are no recrystallized grains in alloy. When the strain rate is 0.1s^-1, the microstructure of alloy is primarily composed of recrystallized grains. So the temperature should be above 573K, the strain rate should be below 0.1s^-1 in the plastic deforming process of AZ31magnesium alloy.3. The results of numerical simulation show that there is mean-stress concentration in the fillet. The mean stress becomes smaller and scatter with the internal fillet radius increasing, the average effective strain becomes larger, but the middle steady deformation area becomes smaller. So the internal fillet radius should be 5mm.