| 摘要 |
PROBLEM TO BE SOLVED: To provide a steel sheet having low anisotropy, and to provide a manufacturing method therefor. SOLUTION: The steel sheet comprises 0.0030% C or less, 0.02% Si or less, 0.15-0.25% Mn, 0.020% P or less, 0.015% S or less, 0.0040% N or less, 0.020-0.070% Al, Nb in an amount of satisfying the expression of 1.0≤Nb/C (ratio by atomic equivalent)≤5.0, B in an amount of satisfying the expression of 1 ppm≤B-(11/14)N≤15 ppm (wherein B and N represent contents of respective elements), and the balance Fe with unavoidable impurities; and has such an in-plane anisotropyΔr of r-values as to satisfy the expression of -0.10≤Δr≤0.10. The manufacturing method comprises the steps of: soaking the slab having the above composition at 1,050°C to 1,300°C by directly heating or reheating the slab; then hot-rolling the soaked slab at a finishing temperature of an Ar3 transformation temperature or higher; subsequently pickling the hot-rolled plate; then cold-rolling it at a rolling rate of 70 to 87%; subsequently annealing the cold-rolled sheet in a continuous annealing line at an annealing temperature between a recrystallization temperature and 850°C; and temper-rolling it. COPYRIGHT: (C)2007,JPO&INPIT
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