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

摘要

hot-dip zinc plating and chromate - free coating with chromate - free cloth as hot-dip galvanized steel , hot-dip galvanized with respect to the coating layer , a high-frequency glow when measuring the Al concentration profile in the depth direction by the discharge emission spectral analysis , a region of the depth 20nm from the outermost surface of the molten zinc plated layer , and has a maximum peak of the Al content , the outermost surface of the molten zinc plated layer from depth 20nm of Al and O in position , Al: 2.5 mass% or more , and O: 2.0 wt% or more and satisfy .