5th International Conference on Advances in Solidification Processes (ICASP-5) 5th International Symposium on Cutting Edge of Computer Simulation of Solidification, Casting and Refining (CSSCR-5)

The endogenous inclusion during solidification may generate from the combination of solute and non-metallic element, i.e, O, S, therefore the formation of such inclusion would take effect to global macrosegregation. To legitimately examine the interaction between endogenous inclusion and macrosgregation, an inclusion-combined macrosegregation model, which coupling the inclusion growth theory with the multicomponent solidification model, has been developed. Here solidification of a ternary alloy (Fe–0.45 wt.%C–1.06 wt.%Mn) is considered and MnS is the only generated inclusion. Spherical granular morphology is assumed for MnS which is treated as another continuous phase, apart from liquid, columnar and equiaxed crystals. Thermodynamic-controlled classical nucleation theory and diffusion-governed growth model are applied to calculate its precipitation process. The mixed solidification model principally takes some features into account as follows: growth of columnar dendrite trunks; nucleation, growth and sedimentation of dendrite equiaxed crystals; thermosolutal convection of the melt; solute transport by both convection and grains(equiaxed and inclusion) floatation; and the columnar-to-equiaxed transition (CET). This inclusion-combined macrosegregation model had been employed to study the formation of macrosegregation and inclusion in a 2.45-ton ingot. The final segregation pattern are in qualitative agreement with the reported experimental results. The formation mechanism of inclusion in such an ingot, and its influence in macrosegreation have been also discussed.