Abstract: Disclosed are a grain-oriented electrical steel sheet having strain regions extending in a direction transverse to a rolling direction at periodic interval s (mm) in the rolling direction. Each strain region has a closure domain region whose width in the rolling direction varies periodically on a steel sheet surface. Each closure domain region satisfies: Wmax/Wmin=1.2 or more and less than 2.5, where Wmax and Wmin respectively denote a maximum width and a minimum width on the steel sheet surface as measured in the rolling direction; Wave being 80 ?m or more, where Wave denotes an average width on the steel sheet surface as measured in the rolling direction; D being 32 ?m or more, where D denotes a maximum depth as measured in the sheet thickness direction; and (Wave*D)/s being 0.0007 mm or more and 0.0016 mm or less.

Abstract: A non-oriented electrical steel sheet has low iron loss even under inverter excitation and can be suitably used as the iron core of a motor. The non-oriented electrical steel sheet has a specific chemical composition and an average grain size r of 40 ?m to 120 ?m. An area ratio R of a total area of grains having a grain size of ? or less of the thickness of the steel sheet to a cross-sectional area of the steel sheet is 2% or greater, and the average grain size r (?m) and the area ratio R (%) satisfy a condition represented by Expression (1), R>?2.4×r+200 (1).

Abstract: To reduce variations in iron loss among materials subjected to magnetic domain refining by electron beam irradiation and to stably obtain good iron loss properties, disclosed is a method of producing a grain-oriented electrical steel sheet including performing magnetic domain refining treatment by irradiating with an electron beam, in a pressure reduced area, a surface of a grain-oriented electrical steel sheet after subjection to final annealing, the method further including: before the irradiating with the electron beam, delivering the grain-oriented electrical steel sheet wound in a coil shape and heating the delivered grain-oriented electrical steel sheet to 50° C. or higher; and then cooling the grain-oriented electrical steel sheet such that the grain-oriented electrical steel sheet has a temperature of lower than 50° C. at the time of entering the pressure reduced area.

Abstract: An excellent low noise property and excellent low iron loss property are obtained. A grain-oriented electrical steel sheet includes refined magnetic domains formed by electron beam irradiation. When the maximum magnetic flux density is 1.7 T, the grain-oriented electrical steel sheet has a residual magnetic flux density of 0.1 to 0.7 times the residual magnetic flux density before the electron beam irradiation and a maximum magnetizing force of 1.1 to 2.0 times the maximum magnetizing force before the electron beam irradiation.

Abstract: A grain-oriented electrical steel sheet to which electron beam irradiation is applied, has a film and a thickness of t (mm), wherein no rust is produced on a surface of the steel sheet after a humidity cabinet test lasting 48 hours at a temperature of 50° C. in an atmosphere of 98% humidity, and iron loss W17/50 after the electron beam irradiation is reduced by at least (?500 t2+200 t?6.5) % of the iron loss W17/50 before the electron beam irradiation and is (5 t2?2 t+1.065) W/kg or less.

Abstract: Provided is a grain-oriented electrical steel sheet having an excellent noise property in an actual transformer. Magnetostrictive properties of the grain-oriented electrical steel sheet are set such that the number of acceleration/deceleration points that are present in the magnetostriction velocity level d?/dt in one period of magnetostrictive vibration is 4 and the magnitude of velocity level change between adjacent velocity change points in an acceleration zone or deceleration zone of magnetostrictive vibration is 3.0×10?4 sec?1 or less.

Abstract: Disclosed are a grain-oriented electrical steel sheet having strain regions extending in a direction transverse to a rolling direction at periodic interval s (mm) in the rolling direction. Each strain region has a closure domain region whose width in the rolling direction varies periodically on a steel sheet surface. Each closure domain region satisfies: Wmax/Wmin=1.2 or more and less than 2.5, where Wmax and Wmin respectively denote a maximum width and a minimum width on the steel sheet surface as measured in the rolling direction; Wave being 80 ?m or more, where Wave denotes an average width on the steel sheet surface as measured in the rolling direction; D being 32 ?m or more, where D denotes a maximum depth as measured in the sheet thickness direction; and (Wave*D)/s being 0.0007 mm or more and 0.0016 mm or less.

Abstract: To predict the iron loss of a non-oriented electrical steel sheet after shearing, a non-oriented electrical steel sheet is sheared to a certain width, and iron loss Wt(B0) of the non-oriented electrical steel sheet after shearing is estimated according to a predetermined relational expression based on iron loss Wn(B1) in a non-machining-affected zone in which no machining strain is introduced by the shearing and iron loss Wi(B2) in a machining affected zone in which machining strain is introduced.

Abstract: A grain oriented electrical steel sheet has a magnetic domain structure modified by strain introduction without a trace of treatment, in which noise generated when the grain oriented electrical steel sheet is used laminated on an iron core of a transformer is effectively reduced by: setting a magnetic flux density B8 to 1.92 T or higher; then setting a ratio of average magnetic domain width of treated surface after strain-introducing treatment Wa to average magnetic domain width before strain-introducing treatment W0 as Wa/W0<0.4; and setting a ratio of Wa to average magnetic domain width of untreated surface Wb as Wa/Wb>0.7; and further setting a ratio of average width of magnetic domain discontinuous portion Wd in the untreated surface to average width of magnetic domain discontinuous portion in treated surface resulting from strain-introducing treatment Wc as Wd/Wc>0.8; and setting Wc<0.35 mm.

Abstract: A method includes preparing a steel slab in which contents of inhibitor components have been reduced, i.e. content of Al: 100 ppm or less, and contents of N, S and Se: 50 ppm, respectively; subjecting the steel slab to hot rolling and then either a single cold rolling process or two or more cold rolling processes interposing intermediate annealing(s) therebetween to obtain a steel sheet having the final sheet thickness; and subjecting the steel sheet to primary recrystallization annealing and then secondary recrystallization annealing. The primary recrystallization annealing includes heating the steel sheet to temperature equal to or higher than 700° C. at a heating rate of at least 150° C./s, cooling the steel sheet to a temperature range of 700° C. or lower, and then heating the steel sheet to soaking temperature at the average heating rate not exceeding 40° C./s in a subsequent heating zone.

Abstract: A grain oriented electrical steel sheet is subjected to magnetic domain refinement by laser irradiation and has magnetic flux density B8 of at least 1.91T, wherein the nitrogen content in the forsterite coating is 3.0 mass % or less. The grain oriented electrical steel sheet satisfies recent demand for iron loss reduction.

Abstract: A grain oriented electrical steel sheet that is subjected to magnetic domain refining treatment by electron beam irradiation and exhibits excellent low-noise properties when assembled as an actual transformer in which tension exerted on the steel sheet by the forsterite film is 2.0 MPa or higher both in a rolling direction and a direction transverse (perpendicular) to the rolling direction, and a ratio of an irradiation pitch in a thermal strain introduced region (B) to a spot diameter (A) on an electron beam irradiation surface satisfies 0.5?B/A?5.0.

Abstract: A grain oriented electrical steel sheet is subjected to magnetic domain refinement by laser irradiation or electron irradiation and exhibits excellent low noise properties and low iron-loss properties when assembled into a real transformer device, by setting: the total tension (A) in rolling direction imparted to the steel sheet by the forsterite coating and the tension coating to be equal to or higher than 10.0 MPa; setting the total tension (B) in a direction orthogonal to the rolling direction imparted to the steel sheet by the forsterite coating and the tension coating to be equal to or higher than 5.0 MPa; and setting the total tension (A) and the total tension (B) to satisfy a formula shown below. 1.0?A/B?5.

Abstract: A method of manufacturing a grain oriented electrical steel sheet includes a rolling a slab for a grain oriented electrical steel sheet to obtain a steel sheet having final sheet thickness; subjecting the steel sheet to decarburizing annealing; coating a surface of the steel sheet with annealing separator mainly composed of MgO; subjecting the steel sheet thus coated to final annealing; providing a tension coating to the steel sheet; and subjecting the steel sheet to magnetic domain refinement by laser irradiation after either the final annealing or provision of the tension coating, wherein (1) the coating weight of the anneal separator is at least 10.0 g/m2; (2) coiling tension at which the steel sheet is coiled after being coated with the annealing separator is 30 N/mm2 to 150 N/mm2; and (3) the average cooling rate in cooling process of the final annealing down to 700° C. is 50° C./hour or less.

Abstract: A grain oriented electrical steel sheet has thickness of forsterite film at bottom portions of grooves formed on a surface of the steel sheet is ?0.3 ?m, groove frequency is ?20%, abundance ratio of grooves crystal grains directly beneath themselves, each crystal grain having orientation deviating from Goss orientation by ?10° and grain size ?5 ?m, total tension exerted on the steel sheet in the rolling direction by the forsterite film and tension coating is ?10.0 MPa, total tension exerted on the steel sheet in a direction perpendicular to the rolling direction by the forsterite film and tension coating is ?5.0 MPa and total tension satisfies 1.0?A/B?5.0, where A is total tension exerted in rolling direction by forsterite film and tension coating, and B is total tension exerted in direction perpendicular to rolling direction by forsterite film and tension coating.

Abstract: A grain oriented electrical steel sheet (1) suppresses the content of Cr in the grain oriented electrical steel sheet to 0.1 mass % or less; (2) sets the coating weight of a forsterite coating, in terms of basis weight of oxygen therein, to at least 3.0 g/m2 and thickness of an anchor portion as a lower portion of forsterite coating to 1.5 ?m or less; and (3) controls setting the magnitude of deflection of a test specimen having length: 280 mm to at least 10mm when the forsterite coating is provided on only one surface thereof and at least 20 mm when forsterite coating and the tension coating are provided on the surface.

Abstract: A grain oriented electrical steel sheet may reduce iron loss of material with linear grooves formed thereon for magnetic domain refinement and offer excellent low iron loss properties when assembled as an actual transformer, where the steel sheet has sheet thickness of 0.30 mm or less, linear grooves are formed at intervals of 2-10 mm in the rolling direction, the depth of each of the linear grooves is 10 ?m or more, the thickness of the forsterite film at bottom portions of the linear grooves is 0.3 ?m or more, total tension applied to the steel sheet by the forsterite film and tension coating is 10.0 MPa or higher in rolling direction, and the proportion of eddy current loss in iron loss W17/50 of the steel sheet is 65% or less when alternating magnetic field of 1.7 T and 50 Hz is applied to the steel sheet in the rolling direction.

Abstract: A device reduces dust for safely preventing laser-irradiation capacity from decreasing due to contamination and reliably reducing iron loss of a grain oriented electrical steel sheet. The device improves iron loss properties of a grain oriented electrical steel sheet by irradiating its surface with laser to reduce iron loss, wherein, distance between a laser beam emission port and a laser irradiation point is L (mm); laser irradiation angle formed by a line linking the emission port and the irradiation point with respect to a direction vertical to the sheet is ? (°); and L?50, the emission port is positioned such that L and ? satisfy: 60?0.3L???60 when L?100; 40?0.1L???60 when 100<L?400; ??60 when L>400.

Abstract: A grain oriented electrical steel sheet is subjected to magnetic domain refining treatment by electron beam irradiation and exhibits excellent low-noise properties when assembled as an actual transformer, in which a ratio (Wa/Wb) of a film thickness (Wa) of the forsierite film on a strain-introduced side of the steel sheet to a film thickness (Wb) of the forsierite film on a non-strain-introduced side of the steel sheet is 0.5 or higher, a magnetic domain discontinuous portion in a surface of the steel sheet on the strain-introduced side has an average width of 150 to 300 ?m, and a magnetic domain discontinuous portion in a surface of the steel sheet on the non-strain-introduced side has an average width of 250 to 500 ?m.

Abstract: A method of manufacturing a grain oriented electrical steel sheet includes subjecting a slab to rolling to a final sheet thickness; subjecting the sheet to subsequent decarburization; applying an annealing separator composed mainly of MgO to a surface of the sheet before subjecting the sheet to final annealing; subjecting the sheet to subsequent tension coating; and subjecting, after the final annealing or the tension coating, the sheet to magnetic domain refining treatment by electron beam irradiation, wherein a degree of vacuum during the electron beam irradiation is 0.1 to 5 Pa, and a tension to be exerted on the steel sheet during flattening annealing is 5 to 15 MPa.