Modeling inclusion removal mechanisms induced by argon blowing and bubble-inclusion interactions in a thin slab casting mold with EMBr

The unique funnel-shaped mold and ultra-high casting speed in thin slab continuous casting and rolling (TSCCR) pose challenges in controlling non-metallic inclusions, which can accumulate at the solidification front and cause surface defects. Argon blowing and electromagnetic braking (EMBr) are commonly applied to optimize the inclusion removal process, but their combined effects on steel flow and inclusion behavior remain unclear. In this work, a 3-dimensional full-scale transient numerical model was established to analyze the liquid-gas-solid multiphase flow within a thin slab mold. A self-developed user-defined function (UDF) program was used to simulate bubble-inclusion collisions. The model was validated using plant-measured data and physical experiments. The analysis reveals that the combined use of argon blowing and EMBr reduces the maximum velocity at the meniscus by 58.4 % and improves temperature uniformity. However, excessive argon flow can induce reverse flow and stagnation regions near the meniscus. When considering the bubble-inclusion collisions, the inclusion removal mechanisms in the mold are classified as free flotation, bubble capture, and flow with the molten steel. Over 45 % of inclusions smaller than 100 μm are captured and removed by bubbles, while the removal ratio for 500 μm inclusions is only 21.40 %. This indicating the argon blowing plays a positive role in inclusion removal and with better removal efficiency for smaller inclusions compared to larger ones. These findings provide insights into optimizing the operating parameters argon blowing and EMBr to enhance inclusion removal in thin slab casting.