スラブのパルス電磁鋳造におけるブリード欠陥の発生機構

抄録

In order to improve the surface qualities of continuously-cast slabs, the pulsative electromagnetic casting (EMC) technique was developed. However, when the plant test was carried out, bleeds occurred at the slab surface. In this work, the mechanism of formation of the bleeds was investigated experimentally, and the numerical simulation of the flow of molten steel and mold flux was also conducted. The thickness of molten mold flux above steel decreased due to the increase in flux consumption when applying the electromagnetic force and the interface between the molten steel and flux fluctuated locally due to the interference of molten steel flows. The bleeds were considered to be caused by insufficient lubrication with mold flux. As countermeasures, the local fluctuation of interface between the molten steel and flux was stabilized by applying a suitable coil current, and the thickness of the molten mold flux was increased by using a flux with a higher melting rate. Finally the bleeds were diminished and a smooth cast surface without defects was obtained at the plant test of the pulsative EMC technique by applying these countermeasures.