| 摘要 |
PROBLEM TO BE SOLVED: To provide a cold rolled steel sheet which has excellent moldability and shape fixability, and has excellent machine production stability, and a method for producing the same. SOLUTION: The cold rolled steel sheet has a composition comprising 0.0010 to 0.0030% C,≤0.05% Si, 0.1 to 0.3% Mn,≤0.05% P,≤0.02% S, 0.02 to 0.10% Al,≤0.005% N, 0.010 to 0.030% Nb and B: 0.0010≤B-11/14×N≤0.0050%, and the balance iron with inevitable impurities. Then, the mean elongation (El<SB>m</SB>) is≥42%, and the mean r value (r<SB>m</SB>) is 1.2 to 1.6. Further, in annealing after cold rolling, the steel sheet is held at a soaking temperature of (820+Nb/15+B-CR) to 860°C for 30 to 200 sec in accordance with a draft CR(%), the Nb content (mass ppm) and the B content (mass ppm), thus the steel sheet can be stably produced by an actual machine without controlling the soaking temperature by pinpoints. COPYRIGHT: (C)2011,JPO&INPIT
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