Method of sequential continuous-casting of different grades of steel

Abstract

The method of sequential continuous-casting of the different grades of steel according to the present invention comprises the steps of: stopping the pouring of a first grade of molten steel into a mold; immersing a cooling material consisting of a steel structure slightly smaller than the inner cross-sectional area of the mold by way of guiding jigs fastened to said cooling material; forming a solidified phase around said cooling material; and merging said solidified phase in a solidified shell developed from the wall of the mold to form a solidified layer shutting the upper portion off the lower portion of the first grade of molten steel. According to the method, the pouring the second grade of molten steel is started before the solidifed layer for shutting the upper portion off the lower portion of the first grade of molten steel as described above and the surface of the first grade of molten steel is solidified completely, and at the same time, the drawing of the cast slab is started again and the change-over to the normal continuous casting of the second grade of molten steel is effected.

Dependencies are inferred from the claim text.