| 摘要 |
PROBLEM TO BE SOLVED: To remove the defects of disadvantages in pressing due to age deterioration, restrictions in heat treatment conditions in a coating stage, and high manufacturing costs and to provide a cold rolled high tensile strength steel sheet excel lent in dent resistance and formability and having high strength. SOLUTION: This steel sheet has a steel composition consisting of, by mass, 0.011-0.04% C, <=1.5% Si, 0.07-2.5% Mn, 0.005-0.10% P, <=0.02% S, 0.01-0.1% Al, <=0.008% N, Ti in an amount satisfying (Ti*%/c%)>=4, where Ti*%=Ti(%)-(48/14)N(%)-(48/32)S(%) is satisfied, and the balance Fe with inevitable impurities and further containing, if necessary, at least either or both of 0.005 0.05% Nb and 0.0001-0.0040% B and/or one or >=2 kinds among <=1.0% Cu, <=1.0% Cr, and <=1.0% Ni. It is preferable that this composition satisfies the following conditions (1) and (2): (1)σ2 -YS>=25N/mm<2> ; (2)α2+ Baking >=275N/mm<2> .
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