Influence of material parameter model on cast-rolling simulation of AZ31 magnesium alloy

COMSOL Multiphysics finite element simulation was used to simulate the process of horizontal twin-roll casting and rolling magnesium alloy. The precise and simplified models of thermal conductivity, specific heat capacity, viscosity and other material parameters changing with temperature of AZ31 magnesium alloy were simulated and compared, and their effects on the simulation results were discussed, and reasonable choices were made. The results show that the setting difference of thermal conductivity has little influence on the simulation results, and the position of solidification welding point changes only 2.5 mm. Whether the latent heat of phase change is considered in the setting of specific heat capacity will make the position difference of solidification welding point 16 mm in the simulation results, so the equivalent specific heat capacity model should be used in the simulation. If it is necessary to qualitatively analyze the rolling section of solidified structure, the viscosity coefficient of the material in solid phase should be reasonably increased. The solid-phase line temperature should be set at the end of the fast growing phase fraction, that is, the solid-phase fraction is 0.75–0.85, and the temperature is 830 K ~ 875 K, which can make the simulation results close to the actual better. The change of density with temperature has little effect on the simulation results of cast-rolling. A reasonable intermediate value can make the simulation more efficient and accurate.