The effects of mold flux contamination on oxide scale formation and hydro-descaling efficiency during steel processing

Abstract Oxide scale formation during thin-slab continuous casting has a complex structure, which is influenced by mold flux contamination, that modifies interfacial reactions during solidification, subsequent reheating, and descaling. While individual aspects of the oxidation behavior of carbon steel have been previously examined, the synergetic effects of mold flux contamination during continuous casting and subsequent reheating on scale modification and the efficiency of hydraulic descaling remain inadequately studied. This study quantitatively examines the effect of flux composition on oxide scale evolution, adhesion, and hydraulic removal in low-carbon steel under simulated industrial conditions. Slab samples with as-cast, cleaned, and flux-coated surfaces were reheated to 1065 °C in a controlled oxidizing atmosphere and immediately descaled using a computer numerical control (CNC)-controlled high-pressure water-jet system. The developed procedures closely simulate industrial conditions. The resulting scale morphologies and residuals after descaling were analyzed using cross-sectional scanning electron microscopy (SEM), Raman spectroscope and quantified through image J analysis. The results demonstrate that the mold flux composition significantly affects the structural evolution and adhesion characteristics of the oxide scale, thereby influencing its hydraulic removal performance.