| 摘要 |
PROBLEM TO BE SOLVED: To produce a high strength thin steel sheet having surface properties, non-aging properties and workability applicable to use for an automotive outer plate and also excellent in secondary working brittleness resistance and to provide a method for producing the same. SOLUTION: This high strength thin steel sheet excellent in secondary working brittleness resistance has a composition composed of, by weight, 0.0040 to 0.02% C, <=0.05% Si, 0.7 to 3.0% Mn, 0.04 to 0.15% P, <=0.02% S, 0.01 to 0.1% Al, <=0.004% N, <=0.2% Nb, and the balance substantially Fe with inevitable impurities and also satisfying the following relationship (1): (12/93)×Nb*/C>=1.0...(1), where Nb*=Nb-(93/14)×N.
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