Surface-treated galvanized steel sheet with superior flat-portion corrosion resistance, blackening resistance, and appearance and corrosion resistance after press forming and aqueous surface-treatment liquid for galvanized steel sheet

摘要

An aqueous surface-treatment liquid is a treatment liquid containing a water-soluble zirconium compound, water-dispersive particulate silica, a silane coupling agent, a vanadic acid compound, a phosphoric acid compound, a nickel compound, and an acrylic resin emulsion in particular proportions. A surface-treated galvanized steel sheet produced using the treatment liquid is a galvanized steel sheet having a surface-treatment coating on a surface thereof, and the coating contains a zirconium compound, particulate silica, a silane-coupling-agent-derived component, a vanadic acid compound, a phosphoric acid compound, a nickel compound, and an acrylic resin in particular proportions. The amount of coating on a zirconium basis is 10 to 200 mg/m². This surface-treated galvanized steel sheet is chromate-free and has superior flat-portion corrosion resistance, blackening resistance, and appearance and corrosion resistance after press forming.