In the production of a non-oriented electrical steel sheet by subjecting a steel slab having a certain component composition to a hot rolling, a hot-band annealing, a cold rolling and a finish annealing, the conditions of the finish annealing are controlled such that a yield stress of the steel sheet after the finish annealing is not less than 480 MPa. Also, when a motor core is produced by using the above steel sheet, there can be provided a non-oriented electrical steel sheet capable of producing a rotor core and a stator core as the same raw material where the stator core is subjected to a stress relief annealing at a soaking temperature of 780 to 950° C. in an atmosphere having a nitrogen content of not more than 30 vol % and a dew point of not higher than −20° C., while a motor core is produced with such a steel sheet.

Disclosed is a high-magnetic-induction oriented silicon steel, wherein the chemical elements thereof are, in mass percentage: Si: 2.0-4.0%; C: 0.03-0.07%; Al: 0.015-0.035%; N: 0.003-0.010%; Nb: 0.0010-0.0500%, the balance being Fe and inevitable impurities. The manufacturing method for the high-magnetic-induction oriented silicon steel includes the steps of: (1) smelting and casting; (2) heating a slab; (3) hot rolling; (4) cold rolling; (5) decarbonizing and annealing; (6) nitriding treatment; (7) applying an MgO coating; (8) high temperature annealing; and (9) applying an insulating coating; wherein a high-magnetic-induction oriented silicon steel is obtained by the manufacturing method, having an average primary grain size of 14-22 μm and a primary grain size variation coefficient of higher than 1.8; and wherein

[00001]$\mathrm{the}\mathrm{primary}\mathrm{grain}\mathrm{size}\mathrm{variation}\mathrm{coefficient}=\frac{\begin{array}{c}\mathrm{the}\mathrm{average}\mathrm{primary}\\ \mathrm{grain}\mathrm{size}\end{array}}{\begin{array}{c}\mathrm{standard}\mathrm{deviation}\mathrm{of}a\\ \mathrm{primary}\mathrm{grain}\mathrm{size}\end{array}}.$

A grain oriented electrical steel sheet includes a base steel sheet, an oxide layer, and a tension-insulation coating. When a glow discharge spectroscopy is conducted in a region from a surface of the tension-insulation coating to an inside of the base steel sheet, a sputtering time Fe.sub.0.5 at which a Fe emission intensity becomes 0.5 times as compared with a saturation value thereof and a sputtering time Fe.sub.0.05 at which a Fe emission intensity becomes 0.05 times as compared with the saturation value satisfy 0.01<(Fe.sub.0.5−Fe.sub.0.05)/Fe.sub.0.5<0.35. Moreover, a magnetic flux density B8 in a rolling direction of the grain oriented electrical steel sheet is 1.90 T or more.

A method for manufacturing a grain-oriented electrical steel sheet including a step of hot-rolling a slab containing a predetermined component composition with a remainder including Fe and an impurity to obtain a hot-rolled steel sheet, a step of, after carrying out hot-rolled steel sheet annealing on the hot-rolled steel sheet, carrying out cold rolling to obtain a cold-rolled steel sheet, a step of carrying out primary recrystallization annealing including a rapid temperature increase at an average temperature increase velocity V of 400° C./s or more and imparting of a steel sheet tensile force S on the cold-rolled steel sheet, and a step of applying an annealing separating agent to a surface of the cold-rolled steel sheet after the primary recrystallization annealing and then carrying out flattening annealing.

Provided is a non-oriented electrical steel sheet having excellent adhesion with an insulating coating even if the thickness of the insulating coating is reduced. The non-oriented electrical steel sheet of the present disclosure has an insulating coating on at least one surface of the steel sheet, where the insulating coating has a P-concentrated layer on both a surface side and an interface side with a steel substrate, and a P concentration of the P-concentrated layer is higher than a P concentration in the steel substrate.

The present patent application relates to an aqueous composition for coating grain oriented steel, comprising aluminium cations, manganese cations, dihydrogen phosphate, hydrogen phosphate and/or phosphate anions, colloidal silica and optionally iron cations, wherein the aluminium cations, expressed as Al.sub.2O.sub.3, manganese cations, expressed as MnO, dihydrogen phosphate, hydrogen phosphate and/or phosphate anions, expressed as P.sub.2O.sub.5, colloidal silica, expressed as SiO.sub.2, and optionally iron cations, expressed as FeO, which are present in the composition, give the sum formula of (Al.sub.2O.sub.3).sub.2(MnO).sub.1,8-2,4(FeO).sub.0-0,2(P.sub.2O.sub.5).sub.5-7(SiO.sub.2).sub.≥30.

A non-oriented electrical steel sheet has a predetermined chemical composition, and when an average value of Mn concentrations in a range from a surface of a base iron to a position where a depth from the surface of the base iron is 2 μm is set to [Mn.sub.2], and an Mn concentration at a position where a depth from the surface of the base iron is 10 μm is set to [Mn.sub.10], the base iron satisfies the following expression 1.
0.1≤[Mn.sub.2]/[Mn.sub.10]≤0.9  (Expression 1)

Provided are coated metal, the metal having improved properties due to a novel coating, a coating-forming treatment solution for forming the novel coating, and a method for producing the coated metal that has the novel coating. The coated metal includes metal and a coating formed on the metal. The coating includes Si, P, and O, and at least one selected from the group consisting of Mg, Ca, Ba, Sr, Zn, Al, and Mn. The coating includes a compound having a Na Super Ionic Conductor-type (NASICON-type) crystal structure represented by a general formula M.sup.IM.sup.IV.sub.2(M.sup.VO.sub.4).sub.3.

A method for producing a grain oriented electrical steel sheet includes a decarburization annealing process where an oxidation degree PH.sub.2O/PH.sub.2 is controlled, a final annealing process where hydrogen in mixed gas atmosphere is controlled to 50 volume % or more, an annealing separator removing process where water-washing is conducted using solution with inhibitor, a smoothing process where chemical-polished is conducted to control average roughness Ra, and an insulation coating forming process where insulation coating forming solution in which crystalline phosphide is included is applied.

A method for producing a grain oriented electrical steel sheet includes a decarburization annealing process where an oxidation degree PH.sub.2O/PH.sub.2 is controlled, an annealing separator applying process where a mass ratio of MgO and MCl in an annealing separator is controlled, a final annealing process where an oxidation degree is controlled when atmosphere includes hydrogen or a dew point is controlled when atmosphere consists of inert gas, and an insulation coating forming process where a mass ratio of phosphoric acid and metal compound in insulation coating forming solution is controlled.