GALVANIZED STEEL SHEET PROVIDED WITH CHROMATE-FREE COATING SUPERIOR IN WHITE RUST RESISTANCE

摘要

PROBLEM TO BE SOLVED: To provide a corrosion prevention technology which can reliably impart white rust resistance equivalent to that of a conventional chromate coating film to a galvanized steel sheet without causing dross formation that is a practical problem in a real operation, by improving the rust resistance of a galvanizing layer in itself and combining the improved galvanizing layer with a chromate-free coating.;SOLUTION: The galvanized steel sheet provided with the chromate-free coating superior in white rust resistance has the chromate-free coating film formed on a galvanized steel sheet. The hot-dip galvanizing layer comprises 0.08-0.70 mass% Al, 0.0010-0.008 mass% Mn and the balance Zn with unavoidable impurities; has an oxide containing Mn (preferably a complexed oxide of Mn and Al and/or Fe) on its surface; and has a chromate-free coating film with a thickness of 0.2 to 3.0 μm further on the surface.;COPYRIGHT: (C)2008,JPO&INPIT