Large-scale simulation of dendrite growth in directional solidification castings

Abstract

In this study, the growth and distribution of directional solidification (DS) dendrites in entire cross-sections of DS superalloy castings are simulated based on a modified shape function dendritic (MSFD) model coupled with the cellular automaton-finite difference (CA-FD) method. The macro-thermal transfer and columnar grain growth are calculated using CA-FD with a macro time-step, and then, the original and boundary conditions for the dendrite-growth simulation are determined via the interpolation of the macro temperature and the projection of the 3D preferential grain orientation using a matrix, M. The dendrite growth calculation cyclically proceeds based on the MSFD model. It is used to predict the growth of hundreds of dendrites throughout the cross-section of a DS casting by considering the macro-solidification parameters. The MSFD model is further applied to predict the competitive growth of DS dendrites and their distribution in the cross-sections of a spiral selector and a fake single crystal turbine blade. The results of the simulation correlate with the results of the DS experiment. Hence, the modified model coupled with the macro-simulation models can be used to predict the morphology and distribution of DS dendrites with respect to large-scale castings produced by the DS process.