Prediction of Hot Tearing and Grain Structure in TiAl Alloy Casting

Due to the high raw material and production costs, process optimization for casting TiAl alloys using the traditional trial and error method is not a realistic option. To explore the numerical feasibility, the casting process for a typical TiAl alloy I-beam is systematically simulated and used to determine the casting temperature, stress field, and microstructure evolution. Based on these data, the shrinkage porosity, stress concentration, and solidification grain structure were predicted. By comparing the accuracy of the hot tearing simulation results for the rigid shell and linear elastic shell models, the importance of the linear elastic shell for hot tearing prediction is demonstrated. Comparison of the experimental casting internal shrinkage porosity, cracks, and microstructure showed that application of reasonable model parameters enables adequate prediction of the forming defects and microstructure during TiAl alloy solidification. This study provides a theoretical basis and strong support for optimization of the design of casting processes.