Article ID: ISIJINT-2025-108
To achieve both quality and productivity in continuous casting at a high dimension, a new electromagnetic flow control system was proposed, in which AC and DC magnetic fields are superimposed. Numerical simulations and experiments at an industrial continuous casting machine were carried out.
1) A model for predicting bubble defects and mold flux defects by focusing on the steel flow velocity on the wide face and the turbulent kinetic energy on the top surface of the molten steel was developed. The validity of the model was confirmed by comparing it with the actual defect tendency of a continuous casting machine.
2) Applying an AC magnetic field in the upper stage increases the molten steel flow velocity and suppresses entrapment of bubbles on the wide face, but flux engulfment and entrapment increase, presumably due to the larger random motion of particles caused by the increased turbulent kinetic energy.
3) When the AC and DC magnetic fields are superimposed in the upper stage, both bubble defects and mold flux defects can be reduced by optimizing the steel flow and turbulent kinetic energy. As a result, surface defects on steel sheets can be roughly halved compared to the conventional flow control method using only DC magnetic field.
4) The results of this study suggested that it may be possible to control the flow velocity and turbulent kinetic energy by optimizing the AC and DC magnetic field intensities according to the casting conditions, further reducing surface defects caused by bubbles and mold flux.
