PURPOSE: To obtain a double layer cast slab having high separation degree of steel components in a surface layer and an inner layer by reducing the pressure in the separated zone containing the joint part of a divided nozzle, supplying molten steel into a mold and continuously casting the double layer cast slab.
CONSTITUTION: DC magnetic field zone crossing the thickness of the cast slab is formed to the molten steel in the continuous casting mold. The molten steels having different compositions are supplied into the molten steel pool 4 at the upper side and the molten steel pool 5 at the lower side divided with the DC magnetic field zone through two nozzles 2, 3 having different lengths, respectively, and the solidification and the drawing are executed. In such a way, the double layer cast slab is formed with the steels having different compositions in the surface layer 7 and the inner layer 8. Then, as the nozzle 2 for surface layer supplying the molten steel into the molten steel pool at the upper side, at the time of using the nozzle 2 divided into the upper and the lower parts 2a, 2b, while reducing the pressure in the separated zone 2c containing the joint part, the molten steel is supplied into the mold. In such a manner, the double layer cast slab is continuously cast. By this method, the variation of the pouring rate is prevented and the pouring quantity can drastically be stabilized.
TAKEUCHI EIICHI
HISATOMI RYOICHI
ASO TATSUJI
