Finite Element Simulation And Technics Research During The Rolling Process Of AZ31 Magnesium Alloy Sheet

Urgent problems on energy sources and environment stimulate the development of magnesium alloy extensively since 1990. The requirements for magnesium alloy with excellent properties increase continuously all over the world, which lead the way in the growing interest in wrought magnesium. Magnesium sheet has great potential in industrial application because of its excellent performance, therefore developing low price magnesium sheet with excellent properties attract more and more interest. But it is difficult to produce magnesium sheet by rolling because of its hexagonal close packed (hcp) lattice. The rolling deformation of AZ31 magnesium sheet was investigated in this paper by finite element simulation and experimental examination including micro structural analysis, fracture analysis and tensile test. The temperature field, equivalent stress filed and strain filed during rolling process were analyzed and the rolling parameter for AZ31 magnesium sheet was optimized. The main conclusions are drawn as follows:There is obvious temperature effect which intensifies with temperature decreasing and strain increasing during the rolling process of AZ31 magnesium. The temperature distinctions between different layers of the sheet along the normal direction increase with the pass strain, moreover the highest and lowest temperature appear at the center and surface layer of the sheet respectively. The equivalent stress, which distributes evenly along normal direction of the sheet all over the rolling parameters, increasing with strain increasing firstly and then decreases as the strain further increase, but it decrease as the rolling temperature increase. The equivalent strain is less influenced by rolling temperature compared to other simulation conditions. As the initial sheet thickness among 3～10mm, a great and homogeneous equivalent strain can be achieved as the pass strain increase in the range of 20%-60%.The deformation limit increase with the rolling temperature increasing between 250～400℃, which was 24.5%,32.3%,67.8%and above 70% for 250℃,300℃,350℃and 400℃respectively. Grain size can be refined by increasing pass strain, but the microstructure will be inhomogeneous due to the zonal fine grain. Therefore the optimized rolling parameter was 350℃and 40% and excellent mechanical properties can be achieved at the optimized parameter. The ultimate tensile strength, yield strength and elongation are 297MPa,220MPa,17.8% and 308MPa,231MPa,16% for rolling direction and normal direction respectively.