| 摘要 |
PROBLEM TO BE SOLVED: To provide a chromium-free surface treated steel sheet capable of obtaining excellent corrosion resistance, electrodeposition coating adhesion and weldability. SOLUTION: A surface treatment film by a surface treatment composition obtained by compositely adding an organic phosphoric acid compound, a nonionic aqueous bisphenol A type epoxy resin, a vanadate compound, a zirconium fluoride compound and a zirconium carbonate compound in prescribed ratios to a titanium-based aqueous solution obtained by mixing a specified titanium compound with a hydrogen peroxide solution is formed on the surface of a galvanized steel sheet or an aluminum-based plated steel sheet, and preferably, an organic film is formed on the upper layer thereof. The steel sheet has excellent corrosion resistance and weldability, and further has particularly excellent electrodeposition coating adhesion by the addition of the nonionic aqueous bisphenol A type epoxy resin in the surface treatment film. COPYRIGHT: (C)2009,JPO&INPIT
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