Study, Simulation and Optimization of the Induction Reheating of a Magnesium Billet Cast by Thixomag® Process 2001-01-0419
Semi-solid metal forming processes are of large industrial interest for the production of various components. Reduction of macro-segregation, reduction of porosity, possibility of near net shape are the principal advantages over casting, forging and powder metallurgy techniques.
This paper gives a brief description of the Thixomag® process applied to a AZ91D magnesium alloy. As it is well known, special material properties are required for the thixoforming process. It is especially necessary to homogenize the temperature along the billet during the induction reheating. This homogenization of temperature enables to avoid the coarsening of the primary solid phase and defects in the final part. To determine the optimum conditions and to reduce the process duration, numerical simulation has been used. A 2D model, where thermal and electromagnetic are coupled, was built. ANSYS, a commercial and multi-physic simulation software with the Finite Element Analysis (FEA) method was chosen to solve this problem.
This study helps us to decrease the process development duration. After measurements and validation, a parametric study was carried out. Thanks to design of experiment methods, the process could be optimized in term of duration. The most significant parameters among heating step, heating time, voltage, length and number of phases, etc, could be pointed out from this design of experiments methods.
Comparison between simulation results and experimental data such as a study with Infrared camera device was performed and shows good agreement.