Study On Deformation Structure And Texture Of ME21 Rare Earth Magnesium Alloy Under Asymmetric Warm Rolling

Mg-Mn series magnesium alloy has been widely used in recent years,with great welding and corrosion resistance.The high temperature resistance and comprehensive mechanical properties of the alloy are greatly improved after the addition of rare earth element Ce.ME21 rare earth magnesium alloy was first developed by Stolfig company of Germany and used to process plate,profile,auto parts and other products.Rare earth element Ce can form high-temperature stable phase Mg12Ce,which plays the role of binding grain boundary and refining grain.In China,manganese and rare earth cerium are abundant in reserves,and the cost is relatively low,Mn and Ce are more economical to be selected as alloy elements.In this paper,the ME21 magnesium alloy sheet with refined grain and weakened texture was obtained by using asynchronous warm rolling process.Firstly,the numerical simulation of symmetric and asymmetric rolling of the ME21 rare earth magnesium alloy was carried out by using the finite element method.The temperature field,equivalent stress field and equivalent plastic strain field of the rolled plate were analyzed and discussed under different rolling temperature,different roll angular velocity and different rolling reduction.Secondly,the results of equivalent plastic strain and strain rate in the macroscopic finite element are coupled to the micro visco-plastic self-consistent model as initial boundary conditions,and a multi-scale model for the rolling process is established.By debugging the hardening parameters and comparing the simulated stress-strain curve with the tensile curve,the Voce hardening parameters of the ME21 rare earth magnesium alloy were obtained.VPSC(Visco-Plastic Self-Consistent)simulation results show that the axial tensile along RD direction early,basal<a>slip as the main deformation mechanism,prismal<a>for the secondary deformation mechanism,deformation mechanism of start-up depends on external forces along the sliding direction of the cutting stress and the relationship between the size of the critical shear stress,with the increase of plastic strain,cutting stress increases gradually,the basal slip is activated,<a>and<c+a>are competitive relationship.EBSD(Electron Back-Scattered Diffraction)experimental results show that the asymmetric rolling because of the existence of rub pierced area can effectively weaken the base surface texture,the board that 40%rolling reduction compared with 20%rolling reduction of the plank emerged a large number of fine equiaxed crystal,less than 5 μm higher proportion of grain,under different cooling ways,water-cooled plate air cooling plate grain refinement effect is more obvious;Compared with air-cooled plates,water-cooled plates have higher tensile strength and yield strength,the 20%rolling reduction and air-cooled plates have the best plasticity,the elongation is up to 11.64%,the ratio of yield strength to tensile strength is 0.606,and the water-cooled plates with 40%rolling reduction have better comprehensive mechanical properties.The results of stress and strain on the macroscopic scale and the mechanism of deformation texture evolution on the microscopic scale were obtained through multi-scale simulation and experimental comparison,which provided theoretical reference for the process parameter setting and microstructure design of magnesium alloy warm rolling.