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|1. (WO2017187799) TREATED SURFACE STEEL|
|Applicants:||NIPPON PAINT INDUSTRIAL COATINGS CO., LTD.
NIPPON STEEL & SUMIKIN COATED SHEET CORPORATION
|Title:||TREATED SURFACE STEEL|
[Problem] To provide a treated surface steel with edge corrosion resistance at least equal to chromate treatment without using hexavalent chromium. [Solution] The present invention is a treated surface steel in which a coating film is formed on the surface of steel via a plated layer and the plated layer is obtained by immersing the steel in an Mg-containing galvalume bath. The treated surface steel is characterized in that: the coating film is formed using a coating composition containing a coating film-forming resin, a cross-linking agent, a specified vanadium compound and trimagnesium phosphate; the vanadium compound is a compound having a specific electric conductivity and the content of the vanadium compound is limited to a specified amount with respect to 100 mass% of the total of the coating film-forming resin solids and the cross-linking agent solids; the vanadium compound has a specified pH; and the content of the trimagnesium phosphate is a specified amount with respect to 100 mass% of the total of the coating film-forming resin solids and the cross-linking agent solids.