Impact of the Electromagnetic Brake Position on the Flow Structure in a Slab Continuous Casting Mold: An Experimental Pa
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, BERND WILLERS
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Flow measurements are performed in a slab model for continuous casting of steel under the influence of a ruler type Electromagnetic Brake (EMBr). The Mini-LIMMCAST facility utilizes the low melting GaInSn alloy for flow modeling. Two-dimensional velocity distributions in the center plane of the rectangular mold with a cross section of 300 35 mm2 are determined by means of the ultrasound Doppler velocimetry. This study especially focuses on the influence of the vertical position of the EMBr and its magnetic flux density as well as the effect of different immersion depths of the submerged entry nozzle. The horizontal flow velocity just below the free surface can effectively be reduced by choosing an optimal position of the EMBr, while an improper positioning even increases the near-surface velocity compared to the case without activated brake. A general braking effect of the EMBr on the submerged jet is not observed. The decisive mechanism for controlling the near-surface flow results from a modification of the jet geometry and a reorganization of the flow field. In terms of an effective flow control an appropriate positioning of the EMBr has at least the same significance as the regulation of the magnetic field strength. https://doi.org/10.1007/s11663-019-01721-x Ó The Minerals, Metals & Materials Society and ASM International 2019
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INTRODUCTION
ELECTROMAGNETIC brakes (EMBrs) have been widely used in slab continuous casting for many years to improve the quality of the cast product and to increase the productivity of the process. The history of the application of EMBrs in steel casting ranges from the first application of local brakes over level brakes (single-ruler EMBr) towards flow control brakes/molds (double-ruler EMBr). For the local brake, the electromagnetic field is restricted to a confined area close to the jet, while the level brake applies the magnetic field over the whole width of the mold. Finally, the double-ruler EMBr is composed of two level magnetic fields positioned at the free surface and in the jet region, respectively. The variety of possible combinations of different parameters, such as mold geometry, casting speed, immersion depth, and geometry of the submerged entry nozzle (SEN) or the type, position, and strength of DENNIS SCHURMANN, IVAN GLAVINIC´, BERND WILLERS, KLAUS TIMMEL, and SVEN ECKERT are with the Helmholtz-Zentrum Dresden-Rossendorf e.V. (HZDR), Bautzner Landstraße 400, 01328 Dresden, Germany. Contact e-mail: [email protected] Manuscript submitted June 27, 2019.
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the electromagnetic brake, makes it difficult to find the optimal configuration to achieve the best product quality at the lowest possible cost. The fluid flow in the mold is considered responsible for most of the casting defects that cause quality problems.[1] Therefore, systematic research into the process continues to be important and relevant to industrial applications today. Recent reviews by Thomas and Cho[2,3] give a very detailed overview of previous research activities wit
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