CHROMATE-FREE FILM-COVERED HOT-DIP GALVANIZED STEEL SHEET POSSESSING HIGH CORROSION RESISTANCE

摘要

Disclosed is a chromate-free film-covered hot-dip galvanized steel sheet comprising a hot-dip galvanized layer and a chromate-free film. The results of the measurement of an Al concentration profile in the direction of depth by a high-frequency glow discharge emission spectral analysis of the hot-dip galvanized layer show that a maximum Al content peak appears in a region of a depth of 20 nm from the uppermost surface of the hot-dip galvanized layer and Al and O at a position of a depth of 20 nm from the uppermost surface of the hot-dip galvanized layer satisfy Al: not less than 2.5% by mass and O: not less than 2.0% by mass.