Optimization of Thixomolding Process for Semisolid AM50 Magnesium Alloy by Numerical Simulation

Abstract

To study the influence of barrel temperature, injection velocity, rotation speed and mold temperature on the quality and properties of products during molding process of thixomolding semisolid slurry, a series of thixomolding processes for semisolid AM50 products were simulated under different processing conditions. The results show that the key parameters of simulated results were influenced by the viscosity that was controlled by barrel temperature and rotation speed during preparation of semisolid slurry before injection. However, the results for different injection velocities demand on the role of shear process of injection nozzle and gate, while the mold temperature had a weak effect on the results. Through the analysis of simulated results, using the optimized parameters, the results of the numerical simulation of the filling process demonstrate that the cavity was filled smoothly and completely. The differences of the results were mainly located at the cold plug catcher of runner system, and the results were almost constants and the distributions are uniform at the shell. Optimal conditions were: barrel temperature 600°C, rotation speed 168 m/s, injection speed 2.09 m/s, mold temperature 230°C. The use of numerical simulation technology could efficiently predict filling defects in semi-solid thixomolding process, optimize the forming process, and provide a reference for mold designs. Microstructure evolution mechanism of AM50 was carefully analyzed.