2004 Volume 44 Issue 3 Pages 556-564
In a continuous casting process, it is essential to prevent the surface defects which are caused by the entrapments of both mold powder and argon gas bubbles. It is well known through experiments that the decrease in the molten steel flow velocity just under the free surface is one of the most effective methods for the prevention of mold powder entrapments. For this purpose, we have already employed the electromagnetic force by the ElectroMagnetic Level Stabilizer (EMLS) system, which applies a low frequency alternating magnetic field that moves from the narrow face of the mold to the mold center below the nozzle exits. In this study, the molten steel flow in a mold was numerically analyzed to optimize the conditions for the prevention of the deteriorating phenomena: optimization of electromagnetic force with argon gas bubbling.
Simulation results indicate that argon gas bubbles ascend near the nozzle due to their buoyancy, and ascending argon bubbles induce the upstream of the molten steel. Due to the electromagnetic force, the molten steel is forced to flow toward the magnetic field traveling direction in the region where the magnetic field is imposed. Consequently, the molten steel flows toward the mold center near the free surface with a smaller imposed magnetic field, and it flows toward the narrow face with a larger imposed magnetic filed. A suitable imposed magnetic filed with argon gas bubbling can be chosen to minimize the flow velocity and also the amount of mold powder entrapments.