Surface Treated Steel Sheet

Abstract: [Problem] To improve thermal yellowing resistance of a coating film layer even when the coating film layer contains a vanadium compound. [Solution] A surface-treated steel sheet according to the present invention comprises a base material steel sheet, a Zn-Al-Mg-containing plating layer, a primer coating film layer that contains at least a vanadium compound, and an upper surface coating film layer, wherein in results of analyzing the primer coating film layer via GDS, the strength of vanadium at an interface on the upper surface coating film layer side of the primer coating film layer is not more than 50% of the maximum strength of vanadium in the primer coating film layer, and, in a range up to 1 µm toward the upper surface coating film layer side of the primer coating film layer from an interface of the primer coating film layer on the Zn-Al-Mg-containing plating layer side, the average strength of vanadium exhibits a prescribed ratio or greater with respect to the average strength of magnesium, the average strength of aluminum, and the average strength of zinc.

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