Numerical Study of Argon Bubble Transport and Entrapment in Continuous Casting Using a Multiphase Approach

Argon injection is often used in the primary cooling stage of the continuous casting process, mainly to remove inclusions in the molten steel and to prevent SEN clogging. However, the injected argon gas bubbles can be captured by the growing dendrites and eventually form pinhole defects in the product. This study integrates multiphase flow modeling, Lagrangian bubble tracking, and a bubble entrapment criterion to evaluate bubble transport, meniscus escape, and entrapment in an industrial continuous casting mold. The results show that bubbles smaller than 0.4 mm are more likely to penetrate into deeper regions, whereas bubbles larger than 1 mm almost completely escape from the meniscus. Bubble escape is primarily concentrated between one‐eighth and one‐quarter of the mold width from the SEN, while entrapment occurs mainly within 200 mm below the meniscus. The effects of argon flow rate, casting speed, SEN submergence depth, and slide‐gate opening are further quantified to provide guidance for optimizing argon injection and reducing bubble‐related defects.