Abstract: A non-oriented electrical steel sheet having: low high-frequency iron loss and high magnetic flux density; an inner layer and surface layers provided on both sides of the inner layer, the surface layers and the inner layer having specific chemical compositions; the thickness t of 0.01 mm to 0.35 mm; a multilayer ratio of t1 to t of 0.10 to 0.70, t1 denoting a total thickness of the surface layers; a difference between [Si]1 and [Si]0 of 1.0 mass % to 4.5 mass % or less, [Si]1 denoting a Si content in each of the surface layers and [Si]0 denoting a Si content in the inner layer; and a difference between [Mn]0 and [Mn]1 of 0.01 mass % to 0.40 mass %, [Mn]0 denoting a Mn content at a mid-thickness position t/2 and [Mn]1 denoting an average Mn content in a region from a surface to a position at a depth of ( 1/10)t.

Abstract: When producing a non-oriented electrical steel sheet by subjecting a slab containing predetermined amounts of C, Si, Mn, Al, N, and Cr to hot rolling, hot-band annealing, cold rolling, and finishing annealing in a continuous annealing furnace, the following conditions are used: a maximum reached temperature in the finishing annealing is set to be lower than 900° C.; an average cooling rate from a temperature (maximum reached temperature—50° C.) to 500° C. in a cooling process of the finishing annealing is set to 40° C./s or higher; and a parameter ?/t defined from a plastic elongation ratio ? (%) in a rolling direction between before and after the finishing annealing and a soaking time t (s) in the finishing annealing is set to 0.10 or higher. Thus, a non-oriented electrical steel sheet is obtained.

Abstract: Provided is a non-oriented electrical steel sheet having good fatigue resistance suitable for rotor cores and excellent magnetic properties suitable for stator cores. The non-oriented electrical steel sheet has a chemical composition of C: 0.01% or less, Si: 2.0% to 5.0%, Mn: 0.05% to 5.00%, P: 0.1% or less, S: 0.01% or less, Al: 3.0% or less and N: 0.005% or less, with the balance being Fe and inevitable impurities, where Si+Al is 4.5% or more. For the crystal grains in the steel sheet, the average grain size X1 is 60 ?m to 200 ?m, the standard deviation S1 of the crystal grain size distribution satisfies the specified formula (1), and the skewness ?1 of the crystal grain size distribution is 1.50 or less.

Abstract: Provided are a high-strength non-oriented electrical steel sheet having good fatigue resistance suitable for rotor cores and a non-oriented electrical steel sheet having excellent magnetic properties suitable for stator cores. The non-oriented electrical steel sheet has a chemical composition of C: 0.01% or less, Si: 2.0% to 5.0%, Mn: 0.05% to 5.00%, P: 0.1% or less, S: 0.01% or less, Al: 3.0% or less and N: 0.005% or less, with the balance being Fe and inevitable impurities, where Si+Al is 4.5% or more. For the crystal grains in the steel sheet, the average grain size X1 is 50 ?m or less, the standard deviation S1 of the grain size distribution satisfies the specified formula (1), and the skewness ?1 of the grain size distribution is 2.00 or less.

Abstract: When producing a non-oriented electrical steel sheet by subjecting a slab containing a predetermined composition to hot rolling, hot-band annealing, cold rolling, and finishing annealing in a continuous annealing furnace, the following conditions are used: a maximum reached temperature in the finishing annealing is set to be lower than 900° C.; an average cooling rate from a temperature to 500° C. in a cooling process of the finishing annealing is set to 40° C./s or higher; a parameter ?/t defined from a plastic elongation ratio ? (%) in a rolling direction between before and after the finishing annealing and a soaking time t (s) in the finishing annealing is set to 0.10 or higher; an average ferrite grain size is 50 ?m or larger; and compressive residual stresses ?s and ?c in a sheet width direction at a steel sheet surface and a sheet-thickness center part, respectively, are both 2.0 MPa or higher.

Abstract: 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 t1 with a ratio t1/t of the total thickness t1 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 W10/400 and the sheet thickness t satisfy the following formula (1): W10/400?8+30t??(1).

Abstract: 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.

Abstract: Provided is a method of easily producing a non-oriented electrical steel sheet that contains substantially no Al and contains large amounts of Si and Mn and has low iron loss, comprising hot rolling a slab having a specified chemical composition to obtain a hot-rolled sheet; coiling the hot-rolled sheet; cold rolling the hot-rolled sheet once or twice with intermediate annealing being performed therebetween, to obtain a cold-rolled sheet; and subjecting the cold-rolled sheet to final annealing, wherein the hot-rolled sheet after the hot rolling is cooled at an average cooling rate from 800° C. to 650° C. of 30° C./s or more, and thereafter the coiling is performed at 650° C. or less.

Abstract: Proposed is a non-oriented electrical steel sheet being low in iron loss and excellent in tensile strength and fatigue strength, which has a chemical composition comprising C: not more than 0.005 mass %, Si: 3 to 5 mass %, Mn: not more than 5 mass %, P: not more than 0.1 mass %, S: not more than 0.01 mass %, Al: not more than 3 mass %, N: not more than 0.005 mass %, Zn: 0.0005 mass % to 0.003 mass %, and the remainder being Fe and inevitable impurities, an average crystal grain size being not more than 40 ?m, the number of the inclusions having a diameter of not less than 5 ?m being not more than 5/mm2, a tensile strength being not less than 600 MPa, and the fatigue strength being not less than 450 MPa.

Abstract: Provided is a method of easily producing a non-oriented electrical steel sheet that contains substantially no Al and contains large amounts of Si and Mn and has low iron loss, comprising hot rolling a slab having a specified chemical composition to obtain a hot-rolled sheet; coiling the hot-rolled sheet; cold rolling the hot-rolled sheet once or twice with intermediate annealing being performed therebetween, to obtain a cold-rolled sheet; and subjecting the cold-rolled sheet to final annealing, wherein the hot-rolled sheet after the hot rolling is cooled at an average cooling rate from 800° C. to 650° C. of 30° C./s or more, and thereafter the coiling is performed at 650° C. or less.

Abstract: A non-oriented electrical steel sheet with an average magnetostriction ?p-p at 400 Hz and 1.0 T of not more than 4.5×10?6, and area ratio of recrystallized grains at a section in rolling direction of steel sheet of 40 to 95% and an average grain size of 10 to 40 ?m is obtained by subjecting a steel slab containing, in mass %, C: not more than 0.005%, Si: 2.8 to 6.5%, Mn: 0.05 to 2.0%, Al: not more than 3.0%, P: not more than 0.20%, S: not more than 0.005%, N: not more than 0.005%, Ti: not more than 0.003%, V: not more than 0.005% and Nb: not more than 0.005% and satisfying Si-2Al—Mn?0 to hot rolling, hot-band annealing, cold rolling and finish annealing under adequate cold rolling and finish annealing conditions, and a motor core is manufactured by such a steel sheet.

Abstract: Provided is a miniaturized motor core with multiple poles for use in motors that require both output density and high efficiency. The motor core is formed by stacking a plurality of electrical steel sheets with a tooth width of 0.5 mm or more and 2.0 mm or less and 12 or more of slots arranged between the teeth, where the electrical steel sheet has an iron loss of 220 W/kg or less when excited at 1.0 T-3000 Hz.

Abstract: Provided is a non-oriented electrical steel sheet that contains substantially no Al and contains large amounts of Si and Mn and has low iron loss, comprising a chemical composition containing C: 0.0050% or less, Si: 2.0% or more and 6.0% or less, Mn: 1.0% or more and 3.0% or less, P: 0.20% or less, S: 0.0050% or less, N: 0.0050% or less, Al: 0.0050% or less, and one or more selected from B: 0.0001% or more and 0.0050% or less, Nb: 0.0001% or more and 0.0050% or less, and V: 0.0005% or more and 0.0500% or less, with a balance consisting of Fe and inevitable impurities, wherein a number density of Si—Mn nitrides with an average diameter of 50 nm or more and 500 nm or less is 1 or less per ?m3.

Abstract: Provided is a laser machining method that causes no degradation in magnetic properties for thin electrical steel sheets. An electrical steel sheet machining method comprises machining an electrical steel sheet to a predetermined shape by melt-cutting the electrical steel sheet using a laser, wherein a scanning rate of the laser in the melt-cutting is 10000 mm/min or more.

Abstract: A non-oriented electrical steel sheet with an average magnetostriction ?p-p at 400 Hz and 1.0 T of not more than 4.5×10?6, and area ratio of recrystallized grains at a section in rolling direction of steel sheet of 40 to 95% and an average grain size of 10 to 40 ?m is obtained by subjecting a steel slab containing, in mass %, C: not more than 0.005%, Si: 2.8 to 6.5%, Mn: 0.05 to 2.0%, Al: not more than 3.0%, P: not more than 0.20%, S: not more than 0.005%, N: not more than 0.005%, Ti: not more than 0.003%, V: not more than 0.005% and Nb: not more than 0.005% and satisfying Si-2Al-Mn?0 to hot rolling, hot-band annealing, cold rolling and finish annealing under adequate cold rolling and finish annealing conditions, and a motor core is manufactured by such a steel sheet.

Abstract: A motor comprising a steel sheet used as a core material of the motor, wherein the steel sheet includes a composition including: by mass %, 0.010% or less of C; 2.0% to 7.0% of Si; 2.0% or less of Al; 0.05% to 1.0% of Mn; 0.005% or less of S; 0.005% or less of N; and balance Fe and inevitable impurities; the steel sheet includes a magnetic flux density changing area where a change ?B in magnetic flux density to a change ?H=50 A/m in a magnetic field, is equal to or higher than 0.50 T; a thickness of the steel sheet is 0.05 mm to 0.20 mm; and an eddy-current loss of the steel sheet, at 1000 Hz?1.0 T, is equal to or less than 0.55 of a total iron loss.

Abstract: A non-oriented electrical steel sheet with an average magnetostriction ?p-p at 400 Hz and 1.0 T of not more than 4.5×10?6, and area ratio of recrystallized grains at a section in rolling direction of steel sheet of 40 to 95% and an average grain size of 10 to 40 ?m is obtained by subjecting a steel slab containing, in mass %, C: not more than 0.005%, Si: 2.8 to 6.5%, Mn: 0.05 to 2.0%, Al: not more than 3.0%, P: not more than 0.20%, S: not more than 0.005%, N: not more than 0.005%, Ti: not more than 0.003%, V: not more than 0.005% and Nb: not more than 0.005% and satisfying Si—2Al—Mn?0 to hot rolling, hot-band annealing, cold rolling and finish annealing under adequate cold rolling and finish annealing conditions, and a motor core is manufactured by such a steel sheet.

Abstract: Provides is a non-oriented electrical steel sheet suitable for use in a rotor of an IPM motor that has excellent magnetic flux density B50 and high-frequency iron loss properties, high tensile strength and fatigue strength, and little variation in tensile strength. The non-oriented electrical steel sheet has a predetermined steel sheet chemical composition and a microstructure in which a ratio of non-recrystallized microstructure is 5% or more and 70% or less and the number of inclusion having a diameter of 5 ?m or more is not more than 5 counts/mm2.

Abstract: 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.

Abstract: Provided is a non-oriented electrical steel sheet having an average crystal grain size of crystal grains being not more than 80 ?m, an area ratio of crystal grains having a grain size of not less than 1.5 times the average crystal grain size being not less than 10%; and an area ratio of crystal grains having aspect ratios of not more than 0.3 being not more than 20%, by subjecting a steel raw material containing, in mass %, C: not more than 0.005%, Si: 2.0 to 5.0%, Mn: 0.05 to 5.0%, Al: not more than 3.0%, and Zn: 0.0003 to 0.0050% to hot rolling, cold rolling, and cold-rolled sheet annealing and by heating the cold-rolled sheet to an annealing temperature between 700 to 850° C. at the average heating rate between 500 and 700° C. in a heating process of the cold-rolled sheet annealing to be not less than 10° C./s.