| 摘要 |
PROBLEM TO BE SOLVED: To stably produce a thinly galvanized steel sheet with a high productiv ity, at the time of plating a cold glavanizing the steel sheet in a continuous galvanizing line, by regulating the content of Al in hot-dip zinc and the temp. of a galvanizing bath. SOLUTION: A cold rolled steel sheet by a dead soft steel contg., by weight, 0.001 to 0.0035% C, <0.10% Si, 0.08 to 2.5% Mn, 0.005 to 0.15% P, 0.001 to 0.02% Si, 0.005 to 0.10% sol.Al, <0.0035% N and 0.03 to 0.15% Ti or furthermore contg. <0.0035% B is subjected to annealing and cooling in a continuous galvanizing line and is thereafter immersed into a galvanizing bath contg. Al, and the surface of the steel is plated with Zn. In that case, the concn. of Al and the temp. of the galvanizing bath are set to the ranges satisfying the inequalities (1), (2) and (3), by which the phases of the initial alloy layer formed on the surface of the steel sheet in the Zn bath are regulated toζones, and by the subsequent wiping treatment, the thinly galvanized steel sheet with <=40g/m<2> Zn coating weight can be produced.
|
