Simulation of microstructure and behavior of interfacial mold slag layers in continuous casting of steel

Abstract

A computational model of heat transfer, solidification and interface behavior during the continuous casting of steel is applied to interpret the crystallization behavior of slag layers in the interfacial gap between the mold and the steel shell. A mechanism for the formation of this crystalline layer is proposed that combines the effects of a shift in the viscosity curve, a decrease in the liquid slag conductivity due to partial crystallization, and an increase in the solid slag layer roughness corresponding to a decrease in solid layer surface temperature with distance down the mold. When the shear stress exceeds the slag shear strength before the axial stress accumulates to the fracture strength, the slag could shear longitudinally inside the layers. The predictions are consistent with measurements conducted in the real process and with the microstructure of analyzed slag samples. © 2006 ISIJ.