| 摘要 |
A cold rolled steel sheet comprising C, Cu, S, Al, N, P, B, Nb, Ti and the balance of Fe and other inevitable impurities, which is capable of enhancing yield strength and lowering in-plane anisotropy by fine CuS precipitate, and a method for manufacturing the same are provided. A cold rolled steel sheet having excellent formability has a composition comprising, by weight percent, 0.005% or less of C, 0.01 to 0.2% of Cu, 0.005 to 0.08% of S, 0.1% or less of Al, 0.004% or less of N, 0.2% or less of P, 0.0001 to 0.002% of B, 0.002 to 0.04% of Nb, 0.005 to 0.15% of Ti, and the balance of Fe and other unavoidable impurities, and satisfies relational expressions, 0.003<=S^*<=0.015, 1<=(Cu/63.5)/(S^*/32)<=30, and 0.8<=(Ti^*/48+Nb/93)/(C/12)<=5.0, wherein S^*=S-0.8Î(Ti-0.8ÎN(48/14))Î(32/48), Ti^*=Ti-0.8ÎS(48/32)-0.8ÎN(48/14), and an average size of CuS precipitate is 0.2 mum or less.
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