The spelter plated steel sheet null which resistance heating discoloration Characteristic, when heating smoking Characteristic, after the heating corrosion resistance and the resistance is attached and is superior in

摘要

PROBLEM TO BE SOLVED: To produce a galvanized steel sheet excellent in all of heating discoloration resistance, fuming properties at the time of heating, corrosion resistance after heating, flawing resistance and adhesion. ;SOLUTION: The surface of a galvanized steel sheet is provided with a chromate film as a 1st layer, in which the coating weight of a film formed by applying a treating soln., in which the weight ratio of trivalent chromium ions/all chromium ions (trivalent chromium ions + hexavalent chromium ions) is controlled to the ratio of 2/10 to 6/10, and as to phosphoric ions, the weight ratio of phosphoric ions/all chromium ions is controlled to the range of 1.0 to 4.0, and by executing drying is ≤100 mg/m2 expressed in terms of metallic Cr and a resin film as a 2nd layer of 0.1 to 3 g/m2 expressed in terms of SiO2 consisting essentially of straight silicone resin on the upper layer of the chromate film.;COPYRIGHT: (C)2000,JPO