| 摘要 |
PURPOSE:To obtain the high-tensile galvanized steel plate with low yield ratio by a method in which a steel having a specific composition with C, Mn, etc., and a CE value (satisfying a specific formula) of 0.17 or more is heated to a specific annealing temperature and then passed through an in-line annealing type continuous hot galvanizer. CONSTITUTION:In the manufacture of the glavanized steel plate by passing a steel strip subjected to a cold rolling through the in-line annealing type continuous hot galvanizer, the steel, consisting of 0.02-0.07% C, 1.5-2.5% Mn, 0.5-1% Cr, 0.01-0.1% Al, 0.07% or less Si, and the remaining Fe, and also the CE value (satisfying the formula) of 0.17 or more, is used as the steel strip. The steel strip is heated to the annealing temperature, or the transformation points AC1-AC3 of the strip, and soon passed through the hot galvanizing bath of the said hot galvanizer to obtain the galvanized steel plate having the low yield ratio of approx. 0.7 or less and the tensile strength of approx. 45kg/mm.<2> or more. |
