Two-Phase Modeling of Macrosegregation in a 231 t Steel Ingot

The formation of macrosegregation in the steel ingots is a multiphase/multiscale flow phenomenon inherently. It still remains a challenge to simulate the macrosegregation in the large steel ingots. The objective of this work is to validate a two phase model by measuring the macrosegregation in a 231 t steel ingot. The model incorporates the descriptions of heat transfer, melt convection, solute transport, and the solid movement on the system scale with microscopic relations for grain nucleation and growth. The model simulates the solidification process by solving the conservation equations of mass, momentum, energy and species for both the liquid and solid phases. Besides, simulations are performed to investigate the influence of the critical solid volume fraction (gsc) on the final macrosegregation pattern which was characterized by experimental measurements. It is indicated that the typical macrosegregation patterns encountered in a large steel ingot, including a positively segregated zone in the hot top and a negatively segregated zone in the bottom part of the ingot, are well reproduced with the current two phase model. Comparison of the simulation results and the measurements is made. It is demonstrated that the critical solid volume fraction gsc is an important factor for the final macrosegregation pattern.