Surface-treated steel sheet

Abstract

A surface-treated steel sheet includes a steel sheet, and an Ni—Co—Fe alloy layer containing Ni, Co, and Fe on the steel sheet surface. In the thickness direction of the Ni—Co—Fe alloy layer, a Co concentration in the Ni—Co—Fe alloy layer is highest at a position which is on an outermost surface side of the Ni—Co—Fe alloy layer relative to a position where the Ni concentration is highest in the Ni—Co—Fe alloy layer, and which is between the outermost surface of the Ni—Co—Fe alloy layer and a depth of 100 nm from the outermost surface. In the Ni—Co—Fe alloy layer, an Ni-concentrated region in which the Ni concentration increases toward the outermost surface of the Ni—Co—Fe alloy layer is formed between the outermost surface of the Ni—Co—Fe alloy layer and the position where the Co concentration is highest.

Dependencies are inferred from the claim text.