| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a method for industrially mass-producing an extra-low carbon steel sheet made of a Ti-deoxidized steel with an extra-low carbon concentration and an extra-low Al concentration which has excellent surface properties while maintaining its deep drawability, and can solve the clogging of an immersion nozzle upon continuous casting and deterioration in the surface properties of the steel caused thereby by allowing the steel to have an inclusion oxygen concentration in a prescribed amount and to contain TiO<SB>x</SB>based inclusions with a predetermined composition. Ž<P>SOLUTION: Disclosed is an extra-low carbon steel sheet having a chemical composition comprising 0.0005 to 0.025% C, 0.003 to 0.12% Si, 0.05 to 2.5% Mn, ≤0.15% P, ≤0.02% S, ≤0.006% N, 0.0002 to 0.003% sol.Al, 0.005 to 0.05% Ti and 0.005 to 0.20% Nb, having the total oxygen concentration T.O of 0.003 to 0.008% and an oxygen concentration Oinc caused by inclusions of 0.0025 to 0.007%, and the balance Fe with impurities, and in which the content of SiO<SB>2</SB>as oxide based inclusions in the steel is <1.0%, ≥90.0% is composed of a ternary system of TiOx, Al<SB>2</SB>O<SB>3</SB>and MnO, and the compositional ranges in the ternary system lie in 50.0 to 95.0% TiOx, 3.0 to 35.0% Al<SB>2</SB>O<SB>3</SB>and 2.0 to 25.0% MnO. Ž<P>COPYRIGHT: (C)2010,JPO&INPIT Ž
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