The steel sheet of the present invention has a steel microstructure containing, in area fraction, martensite: from 20% to 100%, ferrite: from 0% to 80%, and another metal phase: 5% or less, and in which a ratio of a dislocation density in metal phases on a surface of the steel sheet to a dislocation density in the metal phases in a thicknesswise central portion of the steel sheet is from 30% to 80%. The maximum amount of warpage of the steel sheet when the steel sheet is sheared to a length of 1 m in a rolling direction is 15 mm or less.

The steel sheet of the present invention has a steel microstructure containing, in area fraction, martensite: from 20% to 100%, ferrite: from 0% to 80%, and another metal phase: 5% or less, and in which a ratio of a dislocation density in metal phases on a surface of the steel sheet to a dislocation density in the metal phases in a thicknesswise central portion of the steel sheet is from 30% to 80%. The maximum amount of warpage of the steel sheet when the steel sheet is sheared to a length of 1 m in a rolling direction is 15 mm or less.

A non-oriented electrical steel sheet produced by hot-rolling a steel slab containing Si: 2.8 to 6.5 mass % and Zn: 0.0005 to 0.0050 mass % followed by cold rolling and finish annealing, a coating agent containing at least one element from Sn, Sb, P, S, Se, As, Te, B, Pb, and Bi is applied to the surface after annealing forming an insulation coating with nitriding-suppressing ability. Alternatively, an intermediate layer containing at least one element from Sn, Sb, P, S, Se, As, Te, B, Pb, and Bi and having a nitriding-suppressing ability forms on the steel sheet iron matrix after the annealing and forms an insulation coating, without above elements, on the intermediate layer thus obtaining a non-oriented electrical steel sheet wherein a high strength rotor core with and stator core with excellent magnetic is simultaneously obtained, and a motor core including a stator core and rotor core from the steel sheet.

In a production of a non-oriented electrical steel sheet by hot-rolling a steel slab containing Si: 2.8 to 6.5 mass % and Zn: 0.0005 to 0.0050 mass % followed by cold rolling and finish annealing, a coating agent containing at least one element selected from Sn, Sb, P, S, Se, As, Te, B, Pb, and Bi is applied to the steel sheet surface after the finish annealing to form an insulation coating with a nitriding-suppressing ability. Alternatively, an intermediate layer containing at least one element selected from Sn, Sb, P, S, Se, As, Te, B, Pb, and Bi and having a nitriding-suppressing ability is formed on the steel sheet iron matrix after the finish annealing and form an insulation coating not containing above elements is formed on the intermediate layer thus to obtain a non-oriented electrical steel sheet from which a rotor core with high strength and stator core with excellent magnetic properties after the stress-relief annealing can be obtained at the same time, and a motor core comprising a stator core and rotor core is produced from the steel sheet.

A non-oriented electrical steel sheet produced by hot-rolling a steel slab containing Si: 2.8 to 6.5 mass % and Zn: 0.0005 to 0.0050 mass % followed by cold rolling and finish annealing, a coating agent containing at least one element from Sn, Sb, P, S, Se, As, Te, B, Pb, and Bi is applied to the surface after annealing forming an insulation coating with nitriding-suppressing ability. Alternatively, an intermediate layer containing at least one element from Sn, Sb, P, S, Se, As, Te, B, Pb, and Bi and having a nitriding-suppressing ability forms on the steel sheet iron matrix after the annealing and forms an insulation coating, without above elements, on the intermediate layer thus obtaining a non-oriented electrical steel sheet wherein a high strength rotor core with and stator core with excellent magnetic is simultaneously obtained, and a motor core including a stator core and rotor core from the steel sheet.

In a production of a non-oriented electrical steel sheet by hot-rolling a steel slab containing Si: 2.8 to 6.5 mass % and Zn: 0.0005 to 0.0050 mass % followed by cold rolling and finish annealing, a coating agent containing at least one element selected from Sn, Sb, P, S, Se, As, Te, B, Pb, and Bi is applied to the steel sheet surface after the finish annealing to form an insulation coating with a nitriding-suppressing ability. Alternatively, an intermediate layer containing at least one element selected from Sn, Sb, P, S, Se, As, Te, B, Pb, and Bi and having a nitriding-suppressing ability is formed on the steel sheet iron matrix after the finish annealing and form an insulation coating not containing above elements is formed on the intermediate layer thus to obtain a non-oriented electrical steel sheet from which a rotor core with high strength and stator core with excellent magnetic properties after the stress-relief annealing can be obtained at the same time, and a motor core comprising a stator core and rotor core is produced from the steel sheet.

Embodiments of the present disclosure provides an aluminum alloy-plated steel sheet having high surface quality and weldability, a hot-formed member, and methods for manufacturing the aluminum alloy-plated steel sheet and the hot-formed member. The aluminum alloy-plated steel sheet includes: a base steel sheet; and an aluminum alloy plating layer formed on the base steel sheet, wherein the aluminum alloy plating layer includes, by weight %, Zn: 21% to 35%, Si: 1% to 6.9%, Fe: 2% to 12%, and the balance of Al and inevitable impurities.

Embodiments of the present disclosure provides an aluminum alloy-plated steel sheet having high surface quality and weldability, a hot-formed member, and methods for manufacturing the aluminum alloy-plated steel sheet and the hot-formed member. The aluminum alloy-plated steel sheet includes: a base steel sheet; and an aluminum alloy plating layer formed on the base steel sheet, wherein the aluminum alloy plating layer includes, by weight %, Zn: 21% to 35%, Si: 1% to 6.9%, Fe: 2% to 12%, and the balance of Al and inevitable impurities.

The invention relates to biodegradable iron alloy-containing compositions for use in preparing medical devices. In addition, biodegradable crystalline and amorphous compositions of the invention exhibit properties that make them suitable for use as medical devices for implantation into a body of a patient. The compositions include elemental iron and one or more elements selected from manganese, magnesium, zirconium, zinc and calcium. The compositions can be prepared using a high energy milling technique. The resulting compositions and the devices formed therefrom are useful in various surgical procedures, such as but not limited to orthopedic, craniofacial and cardiovascular.

A spot welded joint of at least two steel sheets is provided. At least one of the steel sheets presents yield strength above or equal to 600 MPa, an ultimate tensile strength above or equal to 1000 MPa, uniform elongation above or equal to 15%. The base metal chemical composition includes 0.05≤C≤0.21%, 4.0≤Mn≤7.0%, 0.5≤Al≤3.5%, Si≤2.0%, Ti≤0.2%, V≤0.2%, Nb≤0.2%, P≤0.025%, B≤0.0035%, and the spot welded joint contains a molten zone microstructure containing more than 0.5% of Al and containing a surface fraction of segregated areas lower than 1%, said segregated areas being zones larger than 20 μm.sup.2 and containing more than the steel nominal phosphorus content.

A cold-rolled and heat treated steel sheet, has a composition comprising 0.1%≤C≤0.4%, 3.5%≤Mn≤8.0%, 0.1%≤Si≤1.5%, Al≤3%, Mo≤0.5%, Cr≤1%, Nb≤0.1%, Ti≤0.1%, V≤0.2%, B≤0.004%, 0.002%≤N≤0.013%, S≤0.003%, P≤0.015%. The structure consists of, in surface fraction: between 8 and 50% of retained austenite, at most 80% of intercritical ferrite, the ferrite grains, if any, having an average size of at most 1.5 μm, and at most 1% of cementite, the cementite particles having an average size lower than 50 nm, martensite and/or bainite.

A cold-rolled steel plate (1) and a manufacturing method therefor. The chemical composition of the steel plate (1) in percentage by weight is: C 0.15-0.25%, Si 1.50-2.50%, Mn 2.00-3.00%, P≤0.02%, S≤0.01%, Al 0.03-0.06%, N≤0.01%, with the balance being Fe and impurities. The surface layer has an inner oxide layer (2) with a thickness of 1-5 μm, and there is no enrichment of Si or Mn on the surface. The steel plate (1) has good phosphating performance and formability, with a tensile strength of ≥1180 MPa and an elongation of ≥14%, and has a complex-phase structure of ferrite, martensite, and retained austenite, the content of the retained austenite being not lower than 5%. A dew point is at −25° C. to 10° C. in continuous annealing, such that external oxidation transitions to internal oxidation.