EXTRA-LOW CARBON STEEL SHEET HAVING EXCELLENT SURFACE CHARACTERISTIC, WORK PROPERTY AND FORMABILITY, AND ITS PRODUCING METHOD

摘要

PROBLEM TO BE SOLVED: To provide an extra-low carbon steel sheet which reliably prevents the surface flaws and is excellently worked and formed by having an oxide finely precipitated in solidification while having inclusion hardly developed in molten steel, and its producing method.;SOLUTION: In the method for producing an extra-low carbon steel cast slab, the carbon concentration of the molten steel is reduced to ≤0.005 mass%, Cu and Nb are added into this molten steel and further the oxygen concentration dissolved in the molten steel is adjusted to 0.01 to 0.06 mass%. The resultant molten steel is then cast. The extra-low carbon steel sheet contains ≤0.005 mass% C, ≤0.005 mass% acid-soluble Al and Cu and Nb, and in this steel, the 1000 pieces /cm² to 1,000,000 pieces/cm² fine oxide particles having 0.5 to 30μm diameter are dispersed.;COPYRIGHT: (C)2005,JPO&NCIPI