Abstract: A grain oriented electrical steel sheet includes forsterite film on a surface of base steel sheet; and an aluminum-concentrated portion in at least one of the forsterite film and an interface between the forsterite film and the base steel sheet by a presence ratio expressed as area-occupying ratio of the Al-concentrated portion, of at least 5%, per 10000 ?m2 of the surface of the base steel sheet, which has been subjected to magnetic domain refinement treatment by electron beam irradiation.

Abstract: In a method of producing a grain-oriented electrical steel sheet by hot-rolling a steel slab of a chemical composition containing C: 0.001˜0.10%, Si: 1.0˜5.0%, Mn: 0.01˜1.0%, at least one of S and Se: 0.01˜0.05% in total, sol. Al: 0.003˜0.050%, N: 0.001˜0.020% by mass, subjecting to cold rolling, a primary recrystallization annealing, application of an annealing separator mainly composed of MgO and a finish annealing, a temperature rising rate S1 between 500˜600° C. in the primary recrystallization annealing is made to not less than 100° C./s and a temperature rising rate S2 between 600˜700° C. is made to 30° C./s˜0.6×S1° C./s, while a total content W (mol %) of an element having an ionic radius of 0.6˜1.3 ? and an attracting force between the ion and oxygen of not more than 0.7 ??2 included in the annealing separator to MgO is adjusted to satisfy 0.01S2?5.5?Ln (W)?0.01S2?4.3 to produce a grain-oriented electrical steel sheet having excellent iron loss properties and coating properties.

Abstract: Provided is a method for nitriding a grain-oriented electrical steel sheet which is very useful in obtaining excellent magnetic properties with no variation by immersing a strip in a molten salt bath after cold rolling and before secondary recrystallization annealing during a production process of a grain-oriented electrical steel sheet, to subject the strip to continuous nitriding to uniformly disperse inhibitor forming elements over the full length and full width of the strip.

Abstract: Provided is an apparatus for nitriding a grain-oriented electrical steel sheet which is very useful in obtaining excellent magnetic properties with no variation, that enables generating glow discharge between positive electrodes and negative electrodes disposed in a nitriding zone and irradiating the generated plasma to a strip to perform appropriate nitriding.

Abstract: A grain oriented electrical steel sheet has a total length of cracks in a film on a steel sheet surface, of 20 ?m or less per 10000 ?m2 of the film, wherein magnetic domain refinement interval in a rolling direction of the steel sheet, provided in magnetic domain refinement through substantially linear introduction of thermal strain from one side of the steel sheet corresponding to a winding outer peripheral side of a coiled steel sheet at a stage of final annealing in a direction intersecting the rolling direction; and deflection of 3 mm or less per unit length: 500 mm in the rolling direction of the steel sheet.

Abstract: A method for producing grain-oriented electrical steel sheets includes subjecting a steel slab to hot rolling to obtain a hot rolled sheet, the steel slab having a composition consisting of, by mass % or mass ppm, C: 0.08% or less, Si: 2.0% to 4.5% and Mn: 0.5% or less, S, Se, and O: less than 50 ppm each, sol.Al: less than 100 ppm, N: 80 ppm or less, and the balance being Fe and incidental impurities, and satisfying the relation of sol.Al (ppm)?N (ppm)×(26.98/14.00)?30 ppm; then subjecting the hot rolled sheet to annealing and rolling to obtain a cold rolled sheet; then subjecting the cold rolled sheet to nitriding treatment, under specific condition, before, during or after primary recrystallization annealing; then applying an annealing separator on the cold rolled sheet; and subjecting the cold rolled sheet to secondary recrystallization annealing.

Abstract: When a steel sheet containing Si: 2-5 mass % after cold rolling is subjected to a primary recrystallization annealing and a finishing annealing for secondary recrystallization to form a grain-oriented electrical steel sheet, the primary recrystallization annealing is performed by rapid heating in the heating process and temperature keeping treatment at a certain temperature in the course of the heating to thereby obtain a grain-oriented electrical steel sheet having plural peaks in a distribution of misorientation angle between crystal orientation of secondary recrystallized grains and Goss orientation, wherein misorientation angle of the second smallest peak among the plural peaks is preferably not less than 5° and a grain size of secondary recrystallized grains is not more than 15 mm.

Abstract: A method for producing a grain-oriented electrical steel sheets includes subjecting a steel slab to hot rolling to obtain a hot rolled sheet, the steel slab having a specific composition; then subjecting the hot rolled sheet to annealing and rolling to obtain a cold rolled sheet; then subjecting the cold rolled sheet to nitriding treatment with a nitrogen increase of 50 to 1000 ppm, during or after primary recrystallization annealing; then applying an annealing separator on the cold rolled sheet; and setting the staying time in a temperature range of 300 to 800° C. in the secondary recrystallization annealing to 5 to 150 hours.

Abstract: Grain-oriented electrical steel sheets with good magnetic properties are industrially stably produced, by using as the material, a steel slab having a predetermined composition, wherein after cold rolling and before the start of secondary recrystallization annealing, the cold rolled sheet is subjected to nitriding treatment with nitrogen content of 50 mass ppm or more and 1000 mass ppm or less, and a total content of 0.2 mass % to 15 mass % of a sulfide and/or sulfate is contained in an annealing separator, and a staying time in the temperature range of 300° C. to 800° C. in the heating stage of secondary recrystallization annealing of 5 hours or more is secured to precipitate silicon nitride (Si3N4) and MnS, and using the silicon nitride in combination with MnS as inhibiting force for normal grain growth to significantly reduce variation of magnetic properties.

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: In a method for producing a grain-oriented electrical steel sheet by hot rolling a steel slab having a chemical composition including C: 0.001˜0.10 mass %, Si: 1.0˜5.0 mass %, Mn: 0.01˜0.5 mass %, Al: less than 0.0100 mass %, each of S, Se, O and N: not more than 0.0050 mass % and the remainder being Fe and inevitable impurities, subjecting the resulting hot rolled sheet to a single cold rolling or two or more cold rollings sandwiching an intermediate annealing therebetween to a final thickness, subjecting to a primary recrystallization annealing, applying an annealing separator thereto and then subjecting to a finish annealing, a zone of 550˜700° C. in a heating process of the primary recrystallization annealing is rapidly heated at an average heating rate of 40˜200° C./s, while any temperature zone of 250˜550° C. is kept at a heating rate of not more than 10° C.

Abstract: A method for producing a grain-oriented electrical steel sheet includes hot rolling a raw steel material containing C: 0.002˜0.10 mass %, Si: 2.0˜8.0 mass % and Mn: 0.005˜1.0 mass % to obtain a hot rolled sheet, subjecting the sheet after or without hot band annealing to one or two or more stage cold rollings including an intermediate annealing to obtain a cold rolled sheet having a final sheet thickness, subjecting the rolled sheet to decarburization annealing and primary recrystallization annealing, applying an annealing separator to the sheet surface and subjecting to a final annealing, when rapid heating is performed at a rate of at least 50° C./s in a range of 200˜700° C. of the decarburization annealing, the rolled sheet is subjected to holding at any temperature of 250˜600° C. for 1˜10 seconds to produce a grain-oriented electrical steel sheet being low in the iron loss and small in the deviation of the iron loss value.

Abstract: In a method of producing a grain-oriented electrical steel sheet by hot rolling a steel slab having a chemical composition including C: 0.001˜0.10 mass %, Si: 1.0˜5.0 mass %, Mn: 0.01˜0.5 mass %, S and/or Se: 0.01˜0.05 mass %, sol. Al: 0.003˜0.050 mass % and N: 0.0010˜0.020 mass %, subjecting to single cold rolling or two or more cold rollings including an intermediate annealing therebetween to a final thickness, performing primary recrystallization annealing, and thereafter applying an annealing separator to perform final annealing, a temperature range of 550° C. to 700° C. in a heating process of the primary recrystallization annealing is rapidly heated at an average heating rate of 40˜200° C./s, while any temperature zone of from 250° C. to 550° C. is kept at a heating rate of not more than 10° C./s for 1˜10 seconds, whereby the refining of secondary recrystallized grains is attained and grain-oriented electrical steel sheets are stably obtained with a low iron loss.

Abstract: In a method of producing a grain-oriented electrical steel sheet by hot-rolling a steel slab of a chemical composition containing C: 0.001˜0.10%, Si: 1.0˜5.0%, Mn: 0.01˜1.0%, at least one of S and Se: 0.01˜0.05% in total, sol. Al: 0.003˜0.050%, N: 0.001˜0.020% by mass, subjecting to cold rolling, a primary recrystallization annealing, application of an annealing separator mainly composed of MgO and a finish annealing, a temperature rising rate S1 between 500˜600° C. in the primary recrystallization annealing is made to not less than 100° C./s and a temperature rising rate S2 between 600˜700° C. is made to 30° C./s˜0.6×S1° C./s, while a total content W (mol %) of an element having an ionic radius of 0.6˜1.3 ? and an attracting force between the ion and oxygen of not more than 0.7 ??2 included in the annealing separator to MgO is adjusted to satisfy 0.01S2-5.5?Ln (W)?0.01S2?4.3 to produce a grain-oriented electrical steel sheet having excellent iron loss properties and coating properties.

Abstract: In the production of a grain-oriented electrical steel sheet by hot rolling a steel slab comprising C: 0.001˜0.10 mass %, Si: 1.0˜5.0 mass %, Mn: 0.01˜0.5 mass %, sol. Al: 0.003˜0.050 mass %, N: 0.0010˜0.020 mass %, one or two selected from S and Se: 0.005˜0.040 mass % in total, cold rolling, primary recrystallization annealing, and final annealing, a heating rate S1 between a temperature T1 (° C.): 500+2×(NB?NA) and a temperature T2 (° C.): 600+2×(NB?NA) in a heating process of the primary recrystallization annealing is set to not less than 80° C./sec, and an average heating rate S2 from the temperature T2 to 750° C. is set to 0.1˜0.7 times of S1, whereby a grain-oriented electrical steel sheet having a low iron loss over a full length of a product coil is obtained.

Abstract: In a method of producing a grain-oriented electrical steel sheet by hot rolling a steel slab comprising C: 0.001˜0.10 mass %, Si: 1.0˜5.0 mass %, Mn: 0.01˜1.0 mass %, one or two of S and Se: 0.01˜0.05 mass % in total, sol. Al: 0.003˜0.050 mass % and N: 0.001˜0.020 mass %, cold rolling, subjecting to primary recrystallization annealing, applying an annealing separator and finally subjecting to final annealing, the primary recrystallization annealing is conducted so as to control a heating rate S1 between 500 and 600° C. to not less than 100° C./s and a heating rate S2 between 600 and 700° C. to not less than 30° C./s but not more than 0.6×S1, and as a main ingredient of the annealing separator is used MgO having an expected value ?(A) of citric acid activity distribution of 3.5˜3.8, a cumulative frequency F of 25˜45% when an activity A is not less than 4.0.

Abstract: In a method of producing a grain-oriented electrical steel sheet by subjecting a coil for grain-oriented electrical steel sheet after cold rolling to a primary recrystallization annealing, applying an annealing separator thereon, and conducting final annealing, rapid heating is conducted at a rate of not less than 80° C./sec from 500° C. to 700° C. in the course of heating for the primary recrystallization annealing, and a temperature keeping treatment is conducted for 2 to 100 hours from 700° C. to 1000° C. in the course of heating for the final annealing, and further, the final annealing is preferably conducted by laying a thermal insulation material on an upper surface of a coil supporting stand in an annealing furnace used for the final annealing concentrically from the outer periphery of the coil supporting stand and over an area of not less than 20% of the radius of the coil supporting stand.

Abstract: A grain oriented electrical steel sheet includes forsterite film on a surface of base steel sheet and a selenium-concentrated portion in at least one of the forsterite film and an interface between the forsterite film and the base steel sheet by a presence ratio expressed as area-occupying ratio of the Se-concentrated portion, of at least 2%, per 10000 ?m2 of the surface of the base steel sheet, which has been subjected to magnetic domain refinement treatment by electron beam irradiation.

Abstract: A grain oriented electrical steel sheet has a total length of cracks in a film on a steel sheet surface, of 20 ?m or less per 10000 ?m2 of the film, wherein magnetic domain refinement interval in a rolling direction of the steel sheet, provided in magnetic domain refinement through substantially linear introduction of thermal strain from one side of the steel sheet corresponding to a winding outer peripheral side of a coiled steel sheet at a stage of final annealing in a direction intersecting the rolling direction; and deflection of 3 mm or less per unit length: 500 mm in the rolling direction of the steel sheet.

Abstract: An electrical steel sheet contains, as components, by mass %, 0.005% or less of C, 1.0% to 8.0% of Si, and 0.005% to 1.0% of Mn; one or more selected from Nb, Ta, V, and Zr such that a total content thereof is 10 to 50 ppm; and the balance being Fe and unavoidable impurities, wherein at least 10% of the content of Nb, Ta, V, and Zr is in the form of precipitates; the precipitates have an average diameter (equivalent circle diameter) of 0.02 to 3 ?m; and secondary recrystallized grains of the steel sheet have an average grain size of 5 mm or more.