| 摘要 |
PURPOSE:To prevent the cracking of a flange in a stage for working the flange and to improve the workability by subjecting a steel contg. prescribed percentags of C, Si, Mn, P, Al and N to hot rolling and secondary cold rolling under prescribed conditions. CONSTITUTION:A steel consisting of, by weight, 0.003-0.08% C, <=0.02% Si, 0.05-0.6% Mn, <=0.06% P, 0.005-0.1% Al, <=0.006% N and the balance Fe is refined. The steel is hot rolled, finished at 800-600 deg.C finishing temp., and coiled at <=680 deg.C coiling temp. This hot rolled steel sheet is pickled, cold rolled, annealed by continuous annealing, and subjected to secondary cold rolling at >=15% draft to obtain a material for plating. By this method the cracking of a flange is prevented in a stage for working the flange, and the workability is improved. |
