Microstructural Characteristics of Mold Fluxes Associated to their Thermal Behavior

During continuous casting process of steels, several problems can arise when an inadequate heat removal in the mold is produced. This heat extraction occurs through mold powder layers formed between the cooled mold and the solidifying steel. At operating temperatures, the mold flux forms glassy and crystalline phases that affect the heat transfer from the steel to the mold.In this paper, thermal conductivity results, obtained at 900° C, on two commercial mold powders are presented. From these essays, the interfacial thermal resistances: mold/flux and flux/steel were determined. On longitudinal sections of the samples taken from essays, glassy and crystalline phases were characterized. The thermal behavior of these layers is correlated with the proportion of observed phases and chemical composition of each material.