Electric Current Distribution During Electromagnetic Braking in Continuous Casting
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CONTINUOUS casting (CC) technology is a constantly growing and developing branch of steel casting. Currently, more than 95 pct of the casted steel in the world is formed through continuous casting machines. With increasing casting speeds and production rates, more control is desired for the solidification process to increase the quality of the final products. One of the effective technologies to assist the continuous casting is the so-called electromagnetic braking (EMBr). It is
ALEXANDER VAKHRUSHEV and ABDELLAH KHARICHA are with the Christian-Doppler Laboratory for Metallurgical Applications of Magnetohydrodynamics, Montantuniversita¨t Leoben, Franz-Josef-Strasse 18, 8700 Leoben, Austria. Contact e-mail: [email protected] ZHONGQIU LIU is with the School of Metallurgy, Northeastern University, Shenyang, Liaoning Province 110819, China. MENGHUAI WU and ANDREAS LUDWIG are with the Chair of Simulation and Modeling of Metallurgical Processes, Montantuniversita¨t, FranzJosef-Strasse 18, 8700 Leoben, Austria. GERALD NITZL is with the RHI Magnesita GmbH, Kranichberggasse 6, 1120 Vienna, Austria. YONG TANG and GERNOT HACKL are with the RHI Magnesita Technology Center, Magnesitstrasse 2, 8700 Leoben, Austria. JOSEF WATZINGER is with the Primetals Technologies Austria GmbH, Turmstrasse 44, 4031 Linz, Austria. Manuscript submitted on January 24, 2020.
METALLURGICAL AND MATERIALS TRANSACTIONS B
applied by inducing an external magnetic field across the CC mold cavity normal to the casting direction to generate Lorentz forces, which slow down the liquid core motion and submeniscus velocities and reduce the turbulence level of the hot jets, which are formed due to the fresh melt feeding via a submerged entry nozzle (SEN). As was shown by the authors previously,[1–3] a highly turbulent flow is undesired due to the remelting of the solidified shell at the hot melt impingement areas; thereby EMBr is a favorable practice for the continuous casting process. With the help of the numerical modeling, it is not only possible to understand but also to combat the formation of casting defects. The long-time practical experience reveals that the electromagnetic brake (EMBr) can actually make the situation in the mold cavity even worse, for example, causing the entrapment of argon gas due to the weakening of the magnetic field towards the narrow faces. As was recently reported by Tigrine et al.,[4] the applied magnetic field stabilizes and redistributes the melt core flow, suppressing the buoyancy effects as well; however, the Lorentz force accelerates the flow parallel to the magnetic field boundary layers, causing flow instability. To avoid such situations, it is necessary to properly understand the effect of the magnetic field on the hydrodynamics inside the process.
Since the pioneering works of Takeuchi[5] on the EMBr process in the field of numerical simulation, a wide variety of numerical models have appeared. The requests for the numerical simulation approach have grown over the last decades, especially in the field of metallur
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