Surface Treated Steel Sheet

Abstract: [Problem] To further improve adhesion and corrosion resistance of a film after mold processing. [Solution] A surface-treated steel sheet according to the present invention comprises: a plating layer that is positioned on at least one surface of a steel sheet, and that contains zinc and nickel; a first composite layer that is positioned between the steel sheet and the plating layer and that contains Fe, Zn, and Ni; a chromium-containing composite layer that is positioned on the plating layer and that contains at least Cr; and a coating film that is positioned on the chromium-containing composite layer and that contains an epoxy resin, an isocyanate resin, and silica particles. The adhesion amount of the plating layer is 2-50 g/m2 per side. The chromium-containing composite layer includes a second composite layer that is positioned on the plating layer side and that contains Cr, Zn, and Ni, and a third composite layer that is positioned on the coating film side and that contains Si, N, and a Cr. The adhesion amount of the chromium-containing composite layer is 10-200 mg/m2, in terms of metal Cr equivalent. The thickness of the coating film is 0.5-2.0 µm.

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