Hybrid control of surface behavior on molten metal by mold oscillation and intermittent alternating magnetic field

In a continuous casting of steel, the surface quality of a slab is strongly influenced by mold oscillation. Recently, a new idea in which the imposition of an intermittent alternating magnetic field was synchronized with the mold oscillation has been proposed for the improvement of surface quality under a concept of "soft contacting solidification". The concept is based on the information that the reduction of the contact pressure between a mold and a melt under the imposition of an alternating magnetic field results in good surface duality. However, the most suitable timing for the imposition of the magnetic field in a mold oscillation cycle still has not been determined. To clarify the behavior of the surface wave motion, which is closely related to the contact pressure between a mold and a melt, we have conducted a model experiment on the free surface motion of a molten gallium excited by the synchronous imposition of the intermittent alternating magnetic field and the simulated mold oscillation. The phase difference between the mold oscillation and the magnetic field has been studied from the viewpoint of the suppression of the surface motion. It has been found that the wave shape excited by the synchronous imposition agrees with the numerical superposition of the two wave shapes excited independently by the magnetic field and the mold oscillation, except for the case where a small surface excitation is observed.