Reduction Behavior of SiO2 in Mold Slag by Reaction with High Mn-Al Steel

Abstract

For stable practical operation of continuous casting of high Mn-Al steel such as TWIP steel, design of mold flux chemistry is a key factor for the process. Physico-chemical properties of mold slag (viscosity, interfacial tension, thermal conductivity, solidification behavior) are strongly influenced by the mold flux (slag) chemistry such as CaO/SiO2 ratio. However, during the casting, the mold slag chemistry gradually changes to lower SiO2 concentration due to reaction between the mold slag and molten steel. This affects on the physico-chemical properties of the mold slag, and consequently influences on practical operation of the casting process. In order to find factors which control the slag chemistry change during the reaction between mold slag and molten steel, therefore, the reduction behavior of SiO2 in mold slag by high Mn-Al containing steel was investigated by reacting between molten steel (Fe-C-Mn-Al) and mold slag (CaO-SiO2-Al2O3-MgO) of various compositions and at different temperatures and reaction times. Mold slag compositions after the reactions were measured from steel-slag interface to bulk slag by WDS analysis. It was found that, near the interface in mold slag, SiO2 concentration decreased while Al2O3 and MnO concentrations increased. Chemical reactions occurring at the interface were analyzed based on the experimental observation in the present study.