Prediction of solidification structures in a 9.8 tonne steel ingot

Abstract

Abstract The control of the carbon macrosegregation level in steel ingots is important for the structural integrity of the final component. Previous studies using the SOLID® multiscale modelling software have shown that in order to obtain predictive results for the macrosegregation and the grain structure (CET, grain morphology) in steel ingots, a model needs to account for fragmentation of columnar dendrites as a source of equiaxed grains. The goal of this study is to show that a numerical model that takes into account fragmentation can describe the formation of the structures and the macrosegregation during solidification of a large steel ingot. The present article describes how fragmentation is taken into account in the multiphase numerical model used in the simulations. The simulation results are compared to experimental data from a 9.8 tonne ingot cast in A5/6 steel by ArcelorMittal Industeel. The model correctly reproduces the major features of the experimentally observed structure and macrosegregation. We show that the structures are formed very early on during solidification, whereas macrosegregation develops much more gradually. Our results also underline the importance of liquid flow and grain movement in order to correctly predict the final structure and macrosegregation.