Numerical modeling of columnar to equiaxed transition with consideration of molten steel flow

Abstract

The numerical model of columnar to equiaxed transition (CET) was constructed with consideration of molten steel flow. Solid shell growth was analyzed by using macroscopic heat flow model in addition to heat transfer due to the fluid flow at the solidification front, which was calculated by fluid flow model. At the same time, the dendrite tip temperature and the growth of equiaxed crystal in the undercooled liquid region was estimated and the CET position was diagnosed. By the application of electromagnetic stirrer (EMS), the superheat in the pool diminished and undercooled region was enlarged by heat transfer due to fluid flow at the solidification front. In addition, the ratio of equiaxed zone increased with the increase of grain density by EMS. Therefore, it has been estimated that solidification structure change by application of EMS was caused by superimposition of these two effects. Moreover the size of equiaxed crystal estimated by this model could show good agreements with experimental ones.