White rust resistance and excellent adhesion to galvanized steel coating film

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[docdb]PROBLEM TO BE SOLVED : To produce a non-chromate treated steel sheet excellent in white rust resistance and coating film adhesion. SOLUTION : In a galvanized steel sheet obtained by forming a compound film of one or more kinds selected from rare earth elements and/or the group IVa elements on the surface of plating, the compound film is essentially consisting of the oxide and hydroxide of one or more kinds selected from rare earth elements and/or the group IVa elements, the vicinity of the boundary with the plated layer is essentially consisting of the oxide, and the vicinity of the surface is essentially consisting of the hydroxide, and the compound film preferably has a gradient mixed composition of the oxide and hydroxide in the depth direction.