Nippon Steel Corporation

Yuta Dairokuno

Yasuto Goto

Koki Shimada

Kosuke Kawamoto

Nobusato Kojima

Masaharu Oka

Michihiro Nono

Yuji Kajii

A surface-treated steel sheet of the present disclosure includes a steel sheet, and an alloy layer containing Ni and Co on a surface of the steel sheet. A surface roughness Ra1 of the surface of the alloy layer over a sampling length of 5.0 mm in the width direction of the steel sheet is 2.0 μm or less. Ra2 that denotes the arithmetic mean height of a roughness curve of the surface of the alloy layer over a sampling length of 10 μm in the width direction of the steel sheet is 20 nm or less, and RSm that denotes the mean length of roughness curve elements over the sampling length of 10 μm in the width direction of the steel sheet is 700 nm or more, Ra2 and RSm being measured using an atomic force microscope.

Surface-treated steel sheet

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.

A steel sheet for a drawn can has a predetermined chemical composition and has a ferrite single-phase structure with a crystal grain size number of 11.0 or more, the sheet thickness is 0.15 to 0.50 mm, in an L direction of the steel sheet after an ageing treatment at 100&#xb0; C. for one hour, an yield strength YP is 220 to 290 MPa, a tensile strength TS is 330 to 390 MPa, a total elongation EL is 32% or more, an yield point elongation YP-EL is 0%, an average plastic strain ratio ris more than 1.35, and an in-plane anisotropy &#x394;r is &#x2212;0.30 to +0.15.

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Tokyo, Japan

Yuta Dairokuno