Modeling of molten metal flow in a continuous casting process considering the effects of argon gas injection and static
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INTRODUCTION
IN the slab continuous casting process, the flow field not only has a large influence on heat transfer to the solidifying shell during the critical initial stage of solidification, but it also governs the motion of inclusion particles, which affects the internal cleanness and qualities of the steel. Consequently, the flow velocity of molten steel in a mold is one of the important indices for the control of slab qualities. Argon gas is employed in the continuous casting process to prevent nozzle clogging and promote the flotation of nonmetallic inclusion particles from the molten steel by changing the flow field. On the other hand, in order to get high-quality slabs at a high casting speed, a useful method is the application of the static magnetic field, which is known as the electromagnetic braking (EMBr) technique. The EMBr[1] technique was developed in the beginning of the 1980s. The electromagnetic mold brake ruler (EMBR)[2] and flow-control mold (FCM)[3] were successively developed as the second generation of EMBr techniques. In particular, the FCM can be used to suppress the fluctuations of molten steel at a meniscus and provide uniformity of downward flow in the lower part of the mold. Several physical modeling[2,4] and experimental studies[1–5] have shown that application of a static magnetic field has beneficial effects on continuous casting production. BAOKUAN LI, Professor, Department of Thermal Engineering, The School of Materials and Metallurgy, Northeastern University, Shenyang 110006, P.R. China, is Visiting Researcher, Department of Metallurgy, Graduate School of Engineering, The University of Tokyo. TOSHIMITSU OKANE, Research Associate, Department of Advanced Materials, Graduate School of Frontier Science, and TAKATERU UMEDA, Professor, Department of Metallurgy, Graduate School of Engineering, are with the University of Tokyo, Tokyo 113-8656, Japan. Manuscript submitted December 20, 1999. METALLURGICAL AND MATERIALS TRANSACTIONS B
In order to improve the efficiency of EMBr techniques, it is necessary to understand how steel-gas flow phenomena are affected by the static magnetic field. Some research efforts have been dedicated to gas-liquid flow dynamics, both experimentally with water models and numerically with mathematical models. Bessho et al.[6] compared the calculated flow pattern, gas holdup, and inclusion distribution in a full-scale water model with experimental measurements and observations, and they showed that gas caused a great change in the flow field. Thomas et al.[7,8] have also studied the flow of molten steel and its related phenomena by mathematical and physical models, and they reported flow characteristics in a continuous casting mold. Under application of a static magnetic field, Zeze et al.[2] studied control of flow in the mercury model system of the EMBR and confirmed that a downward plug-like flow could be obtained, depending on the strength of the applied magnetic field. Idogawa et al.[3] described the variation of the flow field in the FCM when gas was not ins
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