A folding plate according to an embodiment of the present invention has first and second support portions located on both sides of a folding portion that is foldable, and is formed as a multilayer structure in which first and second metal sheets of different metal materials are braze-bonded, and thus, is thin and lightweight, has excellent flexibility, and easily dissipates heat.

An electrolyte solution for iron-tungsten plating is prepared by dissolving in an aqueous medium a divalent iron salt (e.g., iron (II) sulfate) and an alkali metal citrate (e.g., sodium citrate, potassium citrate, or other alkali metal citrate) to form a first solution, dissolving in the first solution a tungstate salt (e.g., sodium tungstate, potassium tungstate, or other potassium tungstate) to form a second solution, and dissolving in the second solution a citric acid to form the electrolyte solution. An iron-tungsten coating is formed on a substrate using the electrolyte solution by passing a current between a cathode and an anode through the electrolyte solution to deposit iron and tungsten on the substrate.

A rolled metal sheet includes an obverse surface and a reverse surface that is a surface located opposite to the obverse surface. At least either one of the obverse surface and the reverse surface is a processing object. A method for manufacturing a metal mask substrate includes reducing a thickness of the rolled metal sheet to 10 μm or less by etching the processing object by 3 μm or more by use of an acidic etching liquid, and roughening the processing object so that the processing object becomes a resist formation surface that has a surface roughness Rz of 0.2 μm or more, thereby obtaining a metal mask sheet.

Provided is a low-density clad steel sheet having excellent formability and fatigue properties, including a base material; and cladding materials provided on both side surfaces of the base material, wherein the base material is a lightweight steel sheet including, by weight, C: 0.3 to 1.0%, Mn: 4.0 to 16.0%, Al: 4.5 to 9.0%, and a remainder of Fe and inevitable impurities, and each of the cladding materials is martensitic carbon steel including, by weight, C: 0.1 to 0.45%, Mn: 1.0 to 3.0%, and a remainder of Fe and inevitable impurities.

A surface-treated steel sheet for a battery container includes a steel sheet, an iron-nickel diffusion layer formed on the steel sheet, and a nickel layer formed on the iron-nickel diffusion layer and constituting the outermost layer. When the Fe intensity and the Ni intensity are continuously measured from the surface of the surface-treated steel sheet for a battery container along the depth direction with a high frequency glow discharge optical emission spectrometric analyzer, the thickness of the iron-nickel diffusion layer being the difference (D2−D1) between the depth (D1) at which the Fe intensity exhibits a first predetermined value and the depth (D2) at which the Ni intensity exhibits a second predetermined value is 0.04 to 0.31 μm; and the total amount of the nickel contained in the iron-nickel diffusion layer and the nickel contained in the nickel layer is 10.8 to 26.7 g/m2.

An electrolyte solution for iron-tungsten plating is prepared by dissolving in an aqueous medium a divalent iron salt (e.g., iron (II) sulfate) and an alkali metal citrate (e.g., sodium citrate, potassium citrate, or other alkali metal citrate) to form a first solution, dissolving in the first solution a tungstate salt (e.g., sodium tungstate, potassium tungstate, or other potassium tungstate) to form a second solution, and dissolving in the second solution a citric acid to form the electrolyte solution. An iron-tungsten coating is formed on a substrate using the electrolyte solution by passing a current between a cathode and an anode through the electrolyte solution to deposit iron and tungsten on the substrate.

The present invention provides a nickel-plated and thermally-treated steel sheet with excellent corrosion resistance, in which a remaining nickel amount obtained by analyzing an nickel-iron alloy layer using energy dispersive spectrometry (EDS) or electron probe X-ray microanalysis (EPMA) after pure nickel remaining on the nickel-iron alloy layer was completely removed after the heat treatment for alloying of a nickel plated layer with base iron is 0.1 wt % or more to less than 30 wt % of the total amount of iron and nickel.

A surface-treated steel sheet for a battery container, including a steel sheet, an iron-nickel diffusion layer formed on the steel sheet, and a nickel layer formed on the iron-nickel diffusion layer (and constituting the outermost layer, wherein when the Fe intensity and the Ni intensity are continuously measured from the surface of the surface-treated steel sheet for a battery container along the depth direction with a high frequency glow discharge optical emission spectrometric analyzer, the thickness of the iron-nickel diffusion layer being the difference between the depth at which the Fe intensity exhibits a first predetermined value and the depth at which the Ni intensity exhibits a second predetermined value is 0.04 to 0.31 μm; and the total amount of the nickel contained in the iron-nickel diffusion layer and the nickel contained in the nickel layer is 4.4 g/m.sup.2 or more and less than 10.8 g/m.sup.2.

To provide a surface-treated steel sheet for battery containers excellent in workability while maintaining battery characteristics and liquid leakage resistance, and a manufacturing method thereof. A surface-treated steel sheet for battery containers according to the present invention includes a Ni—Co—Fe-based diffusion alloy plating layer on at least one surface of a base steel sheet, in which the diffusion alloy plating layer is consisted of a Ni—Fe alloy layer and a Ni—Co—Fe alloy layer, which are arranged sequentially from the base steel sheet side, the diffusion alloy plating layer has a Ni coating weight within a range of 3.0 g/m.sup.2 or more and less than 8.74 g/m.sup.2 and a Co coating weight within a range of 0.26 g/m.sup.2 or more and 1.6 g/m.sup.2 or less, with a total of the Ni coating weight and the Co coating weight being less than 9.0 g/m.sup.2, when a surface of the diffusion alloy plating layer is analyzed by an X-ray photoelectron spectroscopy, Co: 19.5 to 60%, Fe: 0.5 to 30%, and Co+Fe: 20 to 70% in atom % are satisfied, and a thickness of the Ni—Fe alloy layer is within a range of 0.3 to 1.3 μm.

A Ni diffusion-plated steel sheet of the present invention includes a base steel sheet and a Fe—Ni diffusion alloy-plating layer positioned on at least one surface of the base steel sheet, a Ni coating weight of the Fe—Ni diffusion alloy-plating layer is 9.0 to 35 g/m.sup.2, a Fe concentration Cs of an outermost layer of the Fe—Ni diffusion alloy-plating layer is 10 to 55 mass %, the base steel sheet has a predetermined chemical composition, and a ferrite grain size number specified by JIS G 0551 (2013) of the base steel sheet is 10.0 or more.