| 摘要 |
PROBLEM TO BE SOLVED: To provide a cold rolled steel sheet which has reduced plane anisotropy in r value, and is applicable to automobiles, house appliances or the like, and to provide a method for producing the same. SOLUTION: The cold rolled steel sheet having reduced plane anisotropy has chemical components comprising, by mass, 0.01 to 0.08% C,≤0.5% Si,≤1.0% Mn,≤0.05% P,≤0.03% S, 0.01 to 0.1% Al,≤0.01% N and 0.01 to 0.05% Ti, and the balance substantially iron, and in which ¾Δr¾<0.15 is satisfied. In the cold rolled steel sheet having excellent bulging formability as well, the plane average value of n value, n* satisfies inequality (1): n*≥0.1×¾Δr¾+0.175. In the method for producing the cold rolled steel sheet having reduced plane anisotropy, the steel is hot-rolled at an Ar<SB>3</SB>transformation point or higher, within 2 seconds after the rolling, cooling is started and is performed at a cooling rate of≥70°C/s over the temperature range of≥100°C, and the steel is subjected to cold rolling and continuous annealing to attain ¾Δr¾<0.15. COPYRIGHT: (C)2004,JPO
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