Finite Element Simulation Of Asymmetric Rolling Process For Magnesium Alloy Sheet

Magnesium alloy sheets have great potentials for industrial applications owing to their superior combination properties. However, the room formability of magnesium produced by conventional preparation and plastic processing are poor due to their intrinsic hexagonal close-packed lattice, which greatly limits the application and development of magnesium alloy sheets. Therefore, the present study aims at improving the room formability of magnesium alloy sheets by asymmetric rolling(ASR). The rolled magnesium alloy AZ31 sheet with a basal texture was used to simulation of the process of ASR. Set up two-dimensional finite element model, used of finite element software DEFORM-2D simulation of ASR process. To further explore magnesium alloy deformation behavior in the ASR process, and the size and distribution of metal flow, stress, strain and strain rate during asymmetric rolling were analyzed.In this paper, the asymmetric rolling of AZ31 magnesium alloy sheet was studied at 300℃.The research results showed that the flow rate of AZ31 sheet increased gradually from the entrance to the exit in the deformation zone. The difference of the flow rate between the upper surface and the lower surface of conventional rolling was very small. The difference of the flow rate between the upper surface and the lower surface of the asymmetric rolling increased gradually, and the maximum value of both was reached at the same time. In addition, equivalent stress, equivalent strain and strain rate at the deformation zone of conventional rolling was between the upper surface and the lower surface of asymmetric rolling. And the effect of asymmetric rolling on the normal stress along the thickness direction was slightly, but it was obvious along the rolling direction.Find reduction optimal ratio of 20% by study the effects of different reductions on equivalent stress, equivalent strain, shear stress and shear strain of the magnesium alloy sheets in asymmetric rolling process. The maximum value of equivalent stress had linear growth trend with the increase of the reduction. When the reduction increased to 20%, the maximum value of equivalent strain and the shear stress during the asymmetric rolling process were 0.39 and 73.04 MPa.The equivalent stress, equivalent strain, shear stress and shear strain at different speed ratios of asymmetric rolling process for magnesium alloy sheet were studied. The maximum value of equivalent stress for magnesium alloy sheet dramatically increased with the increase of the speed ratios, while it reduced instead when the different speed ratios continue to increased. However, the size and distribution of equivalent strain, shear strain during the asymmetric rolling process was less affected by the different speed ratio.The equivalent stress, equivalent strain, shear stress and shear strain at different friction coefficients of asymmetric rolling process for magnesium alloy sheet were studied. The state of asymmetric rolling process when friction coefficient is 0.1 was similar to the conventional rolling. The asymmetry of the equivalent stress for magnesium alloy sheet during the asymmetric rolling process was more prominent and equivalent strain of magnesium alloy sheet increased significantly with the increase of friction coefficient. However, magnesium alloy sheet warped obviously in the early period of stable rolling when the friction coefficient increased to 0.4. The research results showed that the mechanical properties of magnesium alloy sheet showed the best state when the friction coefficient was 0.3.According to the result of simulation experiment, access to a better ASR process parameters and program for the development of technology has provided technical support.