Study On The Thermal Tensile Deformation Behavior And Microstructure Evolution Of Bimodal Non-basel Textured AZ31 Magnesium Alloy Sheet

The deformation behavior of AZ31 magnesium alloy sheet with bimodal non base texture in the temperature range of 200?⁴00?and strain rate of 0.001s^-11s^-1 was studied by isothermal tensile test with Gleeble-3500 thermal simulation machine;based on the tensile data to establish the constitutive equation and processing map of the bimodal non-base texture AZ31 magnesium alloy sheet;through optical microscope?OM?and electron Back Scatter Diffraction?EBSD?methods to study the evolution of the structure during the tensile deformation process.The commercial AZ31 magnesium sheet with base surface texture was subjected to equal channel angular rolling-continuous bending?ECAR-CB?plastic deformation and annealed.It was found that the crystal grains were completely recrystallized after annealing,and the size was relatively uniform,showing an equiaxed shape.After annealing,the orientation of the crystal planes in different areas of the upper surface,neutral layer and lower surface of the plate is mainly biased to around 36°in the rolling direction?RD?,which is a typical bimodal separation non-basal surface texture orientation.The bimodal non-base surface textured AZ31 magnesium alloy sheet was hot-stretched at different temperatures?200?⁴00??and strain rate(0.001-1s^-1).According to the change rule of true stress-true strain curve,it was found that the bimodal non-basal surface texture AZ31magnesium alloy is the material that is more sensitive to temperature and strain rate.During the hot tensile deformation,the peak stress gradually decreases with the decrease of the strain rate or the increase of temperature.According to the true stress-true strain curve of the bimodal non-base surface texture AZ31 magnesium alloy during hot tensile deformation,the modified hyperbolic sinusoidal Arrhenius equation is used to establish the constitutive equation of the bimodal non-basel texture AZ31 magnesium alloy material as:???Comparing the true stress-true strain curve obtained from the experimental test with the constitutive equation after considering the strain compensation to fit the data curve,the effect is perfect.The stress change trend after considering the strain compensation is basically consistent with the actual change trend.Therefore,after considering the strain compensation The constitutive model predicts that the bimodal non-base surface texture AZ31 magnesium alloy material has higher accuracy of flow stress.Based on the dynamic materials model?DMM?,draw the power dissipation diagram and rheological instability diagram under different strains?5%,10%,15%?during the high temperature deformation process to obtain the corresponding thermal processing diagram.It is found that the rheological instability zone is mainly concentrated in the high strain rate area during hot drawing,and the range of the instability zone increases with the increase of the deformation.The processing range is 200?³44?,0.001s^-10.03s^-1.Within the safe range of steady-state processing,the structure during hot tensile deformation under different deformation amounts increases with the amount of deformation,and the recrystallization fraction increases,forming a"necklace"-like structure.During the tensile deformation of the alloy,the grain orientation changes.Compared with the bimodal deflection angle?36°?of the original sample,when the deformation reaches 15%,the deflection angle of the bimodal deflection is reduced to 22°.Continue to gather towards the center.