To provide a surface treated steel sheet for a fuel vessel, which is excellent in corrosion resistance on the external side which does not contact with fuel as well as in corrosion resistance capable of withstanding long use, e.g. for gasoline fuel along, alcohol fuel along, or alcohol-gasoline fuel mixture and further is capable of forming with out lubricating oil.
This galvanized steel sheet has a chromate film, in which Cr:Si:F=1:(0.2 to 5):(0.05 to 5) is satisfied and Cr3+/T.Cr is regulated to 0.1-0.5 and also coating weight expressed in terms of Cr is regulated to (5 to 100) mg/m2, on the internal surface and has a chromate film, in which Si/T.Cr, P/T.Cr, and Cr3+/T.Cr are regulated to 0.1-5.0, 0.4-7.0, and 0.3-0.7, respectively, and also coating weight expressed in terms of Cr is regulated to (5 to 100) mg/m2, on the external surface. Further, is galvanized steel sheet has a chromate film having the same composition as above on the internal surface and has a chromate film, having (100 to 200) mg/m2 coating weight expressed in terms of Cr, and also a resin film of (0.3 to 3) g/m2 by dry weight, formed by applying a resin having ≥35°C Tg and containing 100 pts.wt. of resin having groups OH and COOH, 10-80 pts.wt. of silica, and 1-20 pts.wt. of polyethylene wax having 1-7 μm grain size, on the external surface.
KUROKAWA SHIGEO
OGATA HIROYUKI
OGISHI HIDEO
