| 摘要 |
PROBLEM TO BE SOLVED: To manufacture semi-hard and hard cold roller steel sheets having a high yield ratio and excellent workability for blanking by means of light working which can be done by temper rolling. SOLUTION: A cold rolled steel sheet having a steel composition of, by weight, 0.03-0.17% C, <=0.5% Si, 0.1-1.5% Mn, <=0.08% P, <=0.04% S, 0.005-0.10% Al, <=0.0080% N, further 0.005-0.08% Nb and/or 0.005-0.08% Ti, and the balance essentially iron with inevitable impurities is used. This steel sheet is continuously annealed at 650-900 deg.C. Subsequently, temper rolling of 1.5-4.0% elongation percentage is performed by using a work roll having <=2μm center line average surface roughness (Ra) while pouring tempering liquid on the steel sheet.
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