Mathematical Modeling on the Influence of Casting Parameters on Initial Solidification at the Meniscus of Slab Continuou
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idification[1] of the steel in the mold was extremely crucial to the surface quality of the slab, which depended on many complex and coupled phenomena near the meniscus,[2,3] including the fluid flow, heat transfer, and level and pressure fluctuation near the meniscus caused by the oscillation of the mold.[4] With the cooling of the mold, the solidified slag near the meniscus existed as a slag rim and adhered to the mold. The slag rim moved up and down with the oscillation of the mold, the meniscus moved to or away from the copper plate, and the liquid slag gradually infiltrated into or out of the gap between the copper
XUBIN ZHANG, WEI CHEN, YING REN, and LIFENG ZHANG are with the School of Metallurgical and Ecological Engineering, University of Science and Technology Beijing (USTB), Beijing 100083, P.R. China. Contact e-mail: [email protected] Manuscript submitted November 29, 2018.
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plate and the shell under the influence of the pressure variation near the meniscus.[5,6] The initial solidification of the steel was affected by the heat transfer of the slag[7–9] and the cooling of the copper plate near the meniscus,[10] while the initial solidification had an influence on the formation of oscillation marks[11,12] and hooks[13] at the surface or subsurface of slabs. Oscillation marks on the surface of the slab could decrease the heat transfer from the shell to mold, facilitate the coarse grain at the depression,[14] and even lead to the formation of transverse cracks.[15] Hooks in the mold could entrap floating inclusions, bubbles, and flux.[16] Hence, the research on initial solidification was very necessary. As was reported by Lee[17] and Mills,[18] the ‘‘butterfly effect’’ really occurred in continuous casting of the steel, and the initial solidification was related to casting parameters, including the casting speed,[19] casting superheat, oscillation parameters, the section of the mold, etc. The liquid steel in the slab mold usually existed as the upper backflow and lower backflow,[20] and the upper backflow flowed to the meniscus, which affected the fluid flow and the heat transfer of the steel, as well as the level fluctuation near the meniscus.[21] The initial solidification of the steel decreased when the
molten steel with high superheat moved toward the meniscus, while the cycle of the pressure variation near the meniscus depended on the movement of the slag rim, which was related to oscillation parameters.[22] In the current study, the two-dimensional mold model was applied to investigate the influence of different casting parameters on the initial solidification at the meniscus of the continuous casting mold. Casting parameters included the casting speed, casting superheat, water flow rate in the copper plate, oscillation frequency, and oscillation amplitude. The profile of the meniscus and the slag rim, and the heat flux on the hot face of the copper plate, were compared through the mold model with different locations of the mold and different casting parameters. The depth of oscillatio
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