Modelling the evolution of MnS inclusions and macrosegregation during solidification using a three-phase model

Abstract

Manganese sulphide (MnS) is one of the major non-metallic inclusion in steel which greatly impacts the properties of steels. Previous models have been developed to simulate the dynamics of MnS during solidification without considering the effects of macrosegregation formation. A comprehensive model incorporating the formation kinetics of MnS with a ternary macrosegregation model is presented to investigate the evolution of MnS inclusions and its effects on C and Mn macrosegregation. Classical nucleation theory and a diffusion-controlled growth model are applied to describe the evolution of MnS, which is fully coupled with a two-phase ternary alloy solidification model. The model considers the growth of columnar dendrite trunks, thermosolutal convection of the melt, solute transport by convection and inclusion floatation. It has been applied to a benchmark case, and reasonable results are obtained with a good agreement with the reported experimental ones. The effects of MnS behaviours on the segregation of different solute elements are discussed.