Numerical simulation of thermal stress in cast billets made of AZ31 magnesium alloy during direct-chill casting

A comprehensive two-dimensional (2D) mathematical model based on the ANSYS software has been developed for the computation of the thermomechanical state of the solidifying strand during direct-chill (DC) casting of abnormity ingots and during subsequent cooling. Stress and the strain formation mechanism had been studied. The boundary and initial conditions used for primary and secondary cooling were based on the heat transfer during the solidification of the billet. The effects of casting parameters on the distribution of temperature and stress were researched, which helped to optimize the casting parameters (casting speed, pouring temperature, length of crystallizer, and so on). The simulation results of thermal stress and strain field gave a better understanding of the formation mechanism of some casting defects, which was very useful for optimizing casting parameters and obtaining high-quality billets.