Overview of Electromagnetic Forces to Control Flow during Continuous Casting of Steel

Abstract

During continuous casting of steel slabs, electromagnetic forces can be applied to help control the flow pattern in the mold, augmenting the effects of nozzle and strand geometry, casting speed, and argon injection. Specific configurations include: local, single-ruler, and double-ruler electromagnetic braking, traveling magnetic fields which actively drive flow in the upper mold, (speeding up, slowing, or stirring), and recently combinations of both systems together. Electromagnetic forces have the advantage of being changeable with casting conditions, and naturally adjust with flow variations. This gives this important flow-control tool the potential to stabilize flow in the mold, and to control molten steel velocities to lessen defects. To achieve these benefits in practice, however, requires good understanding of how the defects form, and the details of how the electromagnetic field(s) affect the transient flow. The best way to gain this understanding is by combining validated computational models with plant measurements. This paper shows recent advances using these tools to understand how different configurations affect both steady and transient flow behaviour, the formation of defects from level fluctuations, meniscus freezing, inclusion entrapment, and other mechanisms. These findings suggest promising ways to implement electromagnetic forces to lower defects to improve the process.