Surface properties, workability and method of manufacturing the ultra-low carbon slab and ultra-low carbon steel sheet excellent in formability

摘要

PROBLEM TO BE SOLVED: To provide an extremely low carbon steel sheet surely preventing surface flaw and also, excellent in the workability and the formability by finely precipitating oxides at the solidifying time while developing practically no inclusions in molten steel, and a producing method therefor.;SOLUTION: The method for producing the extremely low carbon steel cast slab, is characterized in that after the molten metal is decarburized to achieve ≤0.005 mass% carbon concentration in the molten steel, Cu, Nb and B are added to the molten steel and further, the dissolved oxygen concentration in the molten steel is adjusted to 0.01-0.06 mass% and the molten metal is cast is cast. Furthermore, the extremely low carbon steel sheet is characterized in that it contains ≤0.005 mass% C, ≤0.005 mass% acid-soluble Al, and further, contains Cu, Nb and B. and further fine oxides having a diameter of 0.5-30μm dispersed therein, in an amount of 1000-1,000,000 pieces/cm².;COPYRIGHT: (C)2006,JPO&NCIPI