关键词: 连续流变成形, 浇注温度, 有限元法, 温度场, 组织

Abstract: To optimize the process parameters for preparing AZ31 Mg-alloy by continuous rheo-extrusion, the temperature and velocity fields at different casting temperatures were modeled by FEM simulation of which the results were verified through some tests to discuss the effect of thermal-fluid coupled field on the microstructure of AZ31 alloy. It was shown that the moving velocity of strand linearly decreases from shoe side to roll side and comes up to its maximum value near the roll surface in the continuous rheo-extrusion process to prepare the semi-solid AZ31 alloy, while the velocity at the shoe surface is zero. The strand temperature decreases gradually from sprue gate to the exit of the roll-shoe gap, and the isothermal line shifts to the roll side. The strand temperature at the exit is basically direct proportional to the casting temperature, and the optimal casting temperature resulting from simulation is in the range from 730 to 770°C for preparing the fine spherical-grain microstructure of the alloy.