A three-phase volume-averaged solidification model considering the growth direction of columnar crystal axis

Abstract

The volume-averaged solidification model has generated considerable research interest in metallurgical areas. The model is complicated but flexible to address many problems faced. However, few previous studies focused on the role of the growth direction of the columnar crystal axis in this model. The current work aims to integrate the columnar growing direction into the volume-averaged solidification model. An optimized algorithm for updating the average length of columnar tips is proposed based on the columnar growing direction. The numerical model was verified by a benchmark experiment of directional solidification. Simulation results agreed well with experimental results, including temperature fields, macrosegregation, macrostructure, and the columnar growing direction. Results showed that the optimized columnar-tip tracking algorithm had some effects on the advancement of the columnar front during initial solidification. The overestimation of the columnar length caused an overestimation of the columnar front. Although the final simulated results did not show a great difference after the optimization, these finds were significant in at least three major respects. First, the columnar crystal growing direction in an ingot could be obtained. The columnar growing direction is also a quality parameter of an ingot. Second, the algorithm for updating the average length of columnar tips made more sense in theory. Third, the optimization could provide a more reliable result during initial solidification. The optimized method is worth developing in the future volume-averaged solidification model.