Fluid Flow-Related Transport Phenomena in Steel Slab Continuous Casting Strands under Electromagnetic Brake
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brake (EMBR) is a technique of imposing a static magnetic field on the mold region of a steel continuous caster. Because of the interaction between the applied magnetic flux and the conductive molten steel inside the mold cavity, a force is generated in the opposite direction of fluid flow, which decelerates the velocity of the steel jet released from the outport of the submerged entry nozzle (SEN). The first local EMBr unit used for the steel continuous casting process was set by ABB Engineering Technologies Company and Kawasaki Steel Corporation in the 1980s.[1] It has been reported that EMBr helps realize more efficient continuous casting process and ensures the high quality of steel products. The technology has been accepted widely by steel industries. The second generation (a level direct current magnetic brake)[2,3] and the third generation (flow control mold) of EMBr[4– 6] have also been developed, and some of them have been used for thin slab casters today.[7–9] Based on reports YUFENG WANG, formerly PhD Student, Department of Material Sciences and Engineering, Missouri University of Science and Technology, Rolla, MO 65409-0330, is now Engineer, with the R&D Group, SSAB, Muscatine, IA 57261. LIFENG ZHANG, Associate Professor, is with the Department of Material Sciences and Engineering, Missouri University of Science and Technology. Contact e-mail: [email protected] Manuscript submitted November 22, 2009. Article published online August 11, 2011. METALLURGICAL AND MATERIALS TRANSACTIONS B
and studies in the past three decades, the advantage of EMBr can be summarized as follows:
Help to achieve a more steady and higher speed
casting, especially for thin slab casting process[10] Optimize the fluid flow pattern in the mold to remove more inclusions Raise the temperature at meniscus[10,11] Lower the top surface velocity and eliminate mold powder entrainment[8,10,12,13] Improve the internal quality of the product[11,13–15] and ensure a good surface quality[10,13–15] Reduce the transition length during steel grade change[16,17] Reduce mold copper wear and prolong the lifetime of the mold[10,18] Be able to produce multilayer steel products[19,20]
The performance of EMBr depends on slab width,[21] casting speed,[21] argon blow rate,[21,22] geometry and submergence depth of the SEN,[21,22] magnetic core position,[23,24] and magnetic flux intensity.[23] The failure to consider these factors may cause the manufacture problem and decrease the quality of the final product. For example, the high position of magnetic core or strong magnetic flux intensity have detrimental effects on the surface and internal qualities of slabs because the steel injection from the SEN could ‘‘bounce’’ against the magnetic field and thus affect the meniscus condition.[23,25] Therefore, the design of EMBr for a casting process is of importance. To make a good design, VOLUME 42B, DECEMBER 2011—1319
different physical models were employed to study the fluid flow-related phenomena inside the caster mold under EMBr, including using low melting p
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