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.

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.

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.

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.

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.

Disclosed is a non-oriented electrical steel sheet having low iron loss in a frequency range of about 400 Hz. The non-oriented electrical steel sheet comprises an inner layer and surface layers, wherein the inner layer and surface layers have specific chemical compositions, each of the surface layers has an in-plane tensile stress of 5 MPa to 50 MPa, the non-oriented electrical steel sheet has a sheet thickness t of 0.01 mm to 0.35 mm, the surface layers have a total thickness t.sub.1 with a ratio t.sub.1/t of the total thickness t.sub.1 to the sheet thickness t being 0.10 to 0.70, the non-oriented electrical steel sheet has an average N content [N] in the total sheet thickness of 40 ppm or less, and an iron loss W.sub.10/400 and the sheet thickness t satisfy the following formula (1):

W.sub.10/400≤8+30t  (1).

Disclosed is a non-oriented electrical steel sheet having low iron loss in a frequency range of about 400 Hz. The non-oriented electrical steel sheet comprises an inner layer and surface layers, wherein the inner layer and surface layers have specific chemical compositions, each of the surface layers has an in-plane tensile stress of 5 MPa to 50 MPa, the non-oriented electrical steel sheet has a sheet thickness t of 0.01 mm to 0.35 mm, the surface layers have a total thickness t.sub.1 with a ratio t.sub.1/t of the total thickness t.sub.1 to the sheet thickness t being 0.10 to 0.70, the non-oriented electrical steel sheet has an average N content [N] in the total sheet thickness of 40 ppm or less, and an iron loss W.sub.10/400 and the sheet thickness t satisfy the following formula (1):

W.sub.10/400≤8+30t  (1).

A process includes applying a slurry to a surface of a metallic article to produce a slurry film on the surface. The slurry is composed of a liquid carrier, chromium and aluminum, and an agent that is reactive with the chromium and aluminum to form intermediary compounds. The article and slurry film are then thermally treated at an activation temperature at which the agent reacts with the chromium and aluminum to form the intermediary compounds. The intermediary compounds deposit the chromium and aluminum on the surface. The thermal treating also diffuses the chromium and aluminum into a sub-surface region of the article such that the sub-surface region becomes enriched with chromium and aluminum.

A process includes applying a slurry to a surface of a metallic article to produce a slurry film on the surface. The slurry is composed of a liquid carrier, chromium and aluminum, and an agent that is reactive with the chromium and aluminum to form intermediary compounds. The article and slurry film are then thermally treated at an activation temperature at which the agent reacts with the chromium and aluminum to form the intermediary compounds. The intermediary compounds deposit the chromium and aluminum on the surface. The thermal treating also diffuses the chromium and aluminum into a sub-surface region of the article such that the sub-surface region becomes enriched with chromium and aluminum.

A method of removing an aluminide diffusion coating from a gas turbine engine component having a nickel alloy base material may comprise: disposing the gas turbine engine component in a solution, the solution including an acid between 5% and 15% vol./vol. and water between 85% and 95% vol./vol.; placing the gas turbine engine component in electrical contact with a graphite plate; and removing the aluminide diffusion coating from the gas turbine engine component in response to placing the gas turbine engine component in electrical contact with the graphite plate and disposing the gas turbine engine component in the solution.