To provide a coated galvanized steel sheet which is excellent in workability (adhesion in a working part), waterproof adhesion, scratch resistance, edge corrosion resistance, and corrosion resistance in a crosscut part and is easy to manufacture.
The coated galvanized steel sheet is a coated steel sheet prepared by forming a zinc or zinc-alloy plating layer, a chemical conversion treatment layer, and a coating film layer on a steel sheet. The chemical conversion treatment layer contains two kinds of fumed silica having 14-9 nm primary particle size and 1500-300 nm primary particle size, respectively, a water- dispersive resin emulsion, and a chromic acid compound. Moreover, the blending ratio by weight, SiO2/Cr, in the case where the coating weight of the fumed silica is expressed in terms of SiO2 and the coating weight of the chromic acid compound is expressed in terms of metallic Cr is regulated to 3-<100 and further, the coating weight of Cr is regulated to (25 to 80) mg/m2.
YAMAJI TAKAFUMI
YAMASHITA MASAAKI
YOSHIDA KEIJI
