Thermal resistance at the interface between mold flux film and mold for continuous casting of steels

Heat transfer from solidifying shell to mold near the meniscus plays an important role for the formation of surface cracks on continuously cast steel products. The heat transfer is influenced substantially by the thermal resistance at the interface between mold flux film and copper mold. Accordingly, a model system consisting of steel shell/mold flux film/copper mold is built to simulate the heat transfer near the meniscus in the mold for continuous casting, and the thermal resistance is determined by measuring temperature gradient in the copper mold in the simulator. The interfacial thermal resistance increases with increasing flux film thickness in contrast to previous observation by others who assumed that the interfacial thermal resistance is constant for different flux film thickness. The interfacial thermal resistance is found to be about 50% of overall thermal resistance for the heat transfer. Mold fluxes for medium carbon steel with higher crystallization temperatures show lower heat flux than those for low carbon steel not due to reduced radiative heat transfer but due to higher interfacial thermal resistance at the same flux film thickness. This arises from the difference in crystallizing behavior such as growth rate of crystalline layer between the two fluxes.