Abstract: A grain oriented electrical steel sheet has sufficiently low iron loss and having less conventionally-concerned warpage of the steel sheet even after the steel sheet is subjected to artificial magnetic domain refining treatment, where strain-introducing treatment is conducted with high energy so that an iron loss-reducing effect can be maximized. The grain oriented electrical steel sheet is obtained by adjusting tension to be applied to a tension-applying insulating coating, or to both surfaces of the steel sheet by the tension-applying insulating coating, before strain-introducing treatment in the range of Formula (1): 1.0?(tension applied to non-strain-introduced surface)/(tension applied to strain-introduced surface)?2.0??(1), and by controlling the amount of warpage of the steel sheet toward the strain-introduced surface side after strain-introducing treatment in the range of 1 mm or more and 10 mm or less.

Abstract: According to the present invention, a grain oriented electrical steel sheet in which iron loss has been further reduced can be obtained by carrying out decarburization annealing as continuous annealing including: (1) heating the steel sheet to a temperature in the range of 700° C. to 750° C. at heating rate of 50° C./second or higher at least in a temperature range of 500° C. to 700° C. in an atmosphere having oxidation potential P(H2O)/P(H2) equal to or lower than 0.05; (2) then cooling the steel sheet to a temperature range below 700° C. in an atmosphere having oxidation potential P(H2O)/P(H2) equal to or lower than 0.05; and (3) reheating the steel sheet to a temperature in the range of 800° C. to 900° C. and retaining the steel sheet at the temperature for soaking in an atmosphere having oxidation potential P(H2O)/P(H2) equal to or higher than 0.3.

Abstract: In a method for producing a grain-oriented electrical steel sheet by hot rolling a steel slab containing, in terms of mass %, C: 0.001˜0.20%, Si: 1.0˜5.0%, Mn: 0.03˜1.0%, one or two of S and Se: 0.005˜0.040% in total, sol. Al: 0.003˜0.050% and N: 0.0010˜0.020%, subjecting to a cold rolling to a final thickness and to a primary recrystallization annealing, applying an annealing separator composed mainly of MgO and then subjecting to final annealing, a heating rate S1 at a zone of 500˜600° C. in a heating process of the primary recrystallization annealing is not less than 100° C./s and a heating rate S2 at a zone of 600˜700° C. is a range of 30˜(0.5×S1)° C./s and an oxidation potential PH2O/PH2 of an atmosphere at a zone of 500˜700° C. is preferably not more than 0.05, whereby secondary recrystallized grains are refined over a full length of a product coil to decrease an iron loss.

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: A grain oriented electrical steel sheet has linear grooves for magnetic domain refinement formed on a surface thereof and may reduce iron loss by using these linear grooves, where the proportion of those linear grooves having crystal grains directly beneath themselves, each crystal grain having an orientation deviating from the Goss orientation by 10° or more and a grain size of 5 ?m or more, is controlled to 20% or less, and secondary recrystallized grains are controlled to have an average ? angle of 2.0° or less, and each secondary recrystallized grain having a grain size of 10 mm or more is controlled to have an average ?-angle variation of 1° to 4°.

Abstract: According to the present invention, a grain oriented electrical steel sheet in which iron loss has been further reduced can be obtained by carrying out decarburization annealing as continuous annealing including: (1) heating the steel sheet to a temperature in the range of 700° C. to 750° C. at heating rate of 50° C./second or higher at least in a temperature range of 500° C. to 700° C. in an atmosphere having oxidation potential P(H2O)/P(H2) equal to or lower than 0.05; (2) then cooling the steel sheet to a temperature range below 700° C. in an atmosphere having oxidation potential P(H2O)/P(H2) equal to or lower than 0.05; and (3) reheating the steel sheet to a temperature in the range of 800° C. to 900° C. and retaining the steel sheet at the temperature for soaking in an atmosphere having oxidation potential P(H2O)/P(H2) equal to or higher than 0.3.

Abstract: A grain oriented electrical steel sheet has thermal strain introduced thereinto in a dotted-line arrangement in which strain-imparted areas are lined in a direction that crosses a rolling direction of the steel sheet, wherein the strain-imparted areas introduced in the dotted-line arrangement have a size from 0.10 mm or more to 0.50 mm or less and an interval between the adjacent strain-imparted areas is from 0.10 mm or more to 0.60 mm or less.

Abstract: A method of manufacturing a grain oriented electrical steel sheet includes subjecting a steel slab to rolling to obtain a steel sheet, subjecting the steel sheet to decarburizing annealing, coating of an annealing separator mainly composed of MgO onto a surface of the steel sheet, and final annealing to obtain a grain oriented electrical steel sheet having at least 4.0 g/m2 of coating weight of forsterite coating formed on the surface of the steel sheet, 0.9 ?m or less of the average grain size of the forsterite coating, and at least 1.91 T of magnetic flux density B8; and linearly irradiating a surface of the grain oriented electrical steel sheet this obtained with a laser having wavelength of 0.2 ?m to 0.9 ?m in a direction intersecting the rolling direction of the steel sheet.

Abstract: A grain oriented electrical steel sheet has linear grooves for magnetic domain refinement formed on a surface thereof and may reduce iron loss by using these linear grooves, where the proportion of those linear grooves having crystal grains directly beneath themselves, each crystal grain having an orientation deviating from the Goss orientation by 10° or more and a grain size of 5 ?m or more, is controlled to 20% or less, and secondary recrystallized grains are controlled to have an average ? angle of 2.0° or less, and each secondary recrystallized grain having a grain size of 10 mm or more is controlled to have an average ?-angle variation of 1° to 4°.

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 has sufficiently low iron loss and having less conventionally-concerned warpage of the steel sheet even after the steel sheet is subjected to artificial magnetic domain refining treatment, where strain-introducing treatment is conducted with high energy so that an iron loss-reducing effect can be maximized. The grain oriented electrical steel sheet is obtained by adjusting tension to be applied to a tension-applying insulating coating, or to both surfaces of the steel sheet by the tension-applying insulating coating, before strain-introducing treatment in the range of Formula (1): 1.0?(tension applied to non-strain-introduced surface)/(tension applied to strain-introduced surface)?2.0??(1), and by controlling the amount of warpage of the steel sheet toward the strain-introduced surface side after strain-introducing treatment in the range of 1 mm or more and 10 mm or less.

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 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 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<0.3.5 mm.

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 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 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 grain oriented electrical steel sheet is subjected to magnetic domain refinement by laser irradiation and has magnetic flux density B8 of at least 1.91 T, 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 (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 10 mm 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 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 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.