Modeling of equiaxed grain evolution and macrosegregations development in Steel Ingots

Abstract

The phenomena responsible for the formation of macrosegregations, and grain structures during solidification are closely related. The development of models combining these two aspects is still at its beginning. The application of these models to processes like steel ingot production is a challenging problem mainly due to the size of the products and the variety of the phenomena to be accounted for. In this article we present simulation results using a multiphase and multiscale model in terms of prediction of grain structures, and macrosegregations during solidification. It is shown for the case of 3.3-ton steel ingot that when the grains are globular, grain settling is the predominant mechanism of macrosegregation formation. However, when the morphology is dendritic, the direct contribution of grain settling on the segregation formation is negligible; the interdendritic flow in the more permeable sedimentation layer controls the macrosegregation. The globular-dendritic morphology evolution and dendritic-to-globular morphological transition with increases in local grain density, and its impact on the macrosegregation are discussed.