Plastical Deformation Behavior Under High Temperature And Numerical Simulation Of AZ31Magnesium Alloy

In this paper, AZ31magnesium alloy was used as experimental materials.The Gleeble-1500D thermal/mechanical simulator was used to the compressiontests of AZ31magnesium alloy under different deformation conditions of hightemperature. And the constitutive equation was built according to theexperimental data. The microstructure of compression specimens under hightemperature was observed and photograghed by Zeiss metallurgical microscope.The influences of dynamic recrystallization process by deformation factors suchas temperature, strain rate and strain was studied and kinetics model of dynamicrecrystallization was established. The extrusion process of AZ31magnesiumalloy under different conditions was simulated by DEFORM-3D softwareaccording to the true stress-strain curves of the compression process.1.The flow stress of AZ31magnesium alloy in the deformation processunder high temperature decreases with increasing temperature and increaseswith increasing strain rate. The stress-strain curves of AZ31magnesium alloyunder different deformation conditions is the style of dynamic recrystallization.After analyzing the true stress-strain curves, we obtain the constitutive equationof AZ31magnesium alloy under different deformation conditions of hightemperature:ε=4.78×10¹⁴[sinh(0.013σ)]^8.678exp (-181756/RT)2.The compression microstructure of AZ31magnesium alloy was analyzedunder high deformation temperature. The results showed that the microstructuremostly consists of twins when temperature from473K～573K and large numberof dynamic recrystallization grains appear at the temperature of673K. Dynamicrecrystallization process is promoted by discreasing strain rate and increasingthe value of strain. The strain rate should be below0.1s-1and the value of strainshould be above0.2. The kinetics equation of dynamic recrystallization was gotaccording to the data of compression deformation:Z=7.62×10¹¹e^59.54εd Z=1.37×10⁶e^49.57εs3.The stress distribution, strain distribution and compressive load of AZ31magnesium alloy in the extrusion process under different temperature, strain rateand extrusion ratio was simulated by DEFORM-3D software. Results are asfollow:The stress and strain distribution of AZ31magneisum alloy blank mostlyconcentrated at the exit of the extursion dies. The effective stress, effective strainand compressive load becomes larger and larger with the increasing of extrusionspeed and ratio. The compressive load and effective stress reduces with theincreasing of extrusion temperature, but the effective strain has little changes.