Numerical simulation of macro--segregation with equiaxed grains movement
等轴晶移动对宏观偏析影响的数值模拟

A mathematical model of equiaxed grains movement and macro-segregation has been built to analyze the fluid flow and species distribution during the metal solidification. The mushy zone was divided into dendrites region and free equiaxed grains region by the dendritic coherency point. Macro-segregation of a steel ingot in a rectangular mold with a riser was simulated and the calculation result was compared with that of an experiment. It shows that the species distribution obtained by the grain movement model is more consistent with experiment comparing to that by the solid skeleton model in mush. The equiaxed grains move with the fluid and accumulate at the bottom center of the ingot during solidification. The cone-shape negative segregation forms after solidification. The positive segregation in the upper center and the negative segregation in the exterior region of the ingot are found at the same time.