A grain oriented electrical steel sheet includes a base steel sheet, an oxide layer, and a tension-insulation coating. When the iron oxide layer is analyzed by a fourier transform infrared spectroscopy, an absorbance A.sub.650 at 650 cm.sup.−1 and an absorbance A.sub.1250 at 1250 cm.sup.−1 satisfy 0.2≤A.sub.650/A.sub.1250≤5.0. Moreover, a magnetic flux density B8 in a rolling direction of the grain oriented electrical steel sheet is 1.90 T or more.

Grain-oriented electrical steel sheet excellent in magnetic properties and adhesion of a primary coating to a base steel sheet and with few defects where the base metal is exposed in point defects and a method for manufacturing grain-oriented electrical steel sheet are provided. This is characterized by being provided with a base steel sheet and a primary coating. The primary coating satisfies (1) Number density D3 of Al concentrated regions: 0.015 to 0.150/μm.sup.2, (2) (Area S5 of regions comprised of anchoring oxide layer regions and Al concentrated regions)/(area S3 of Al concentrated regions)≥0.30, (3) Distance H5 of mean value of heights in thickness direction of regions of comprised of anchoring oxide layer regions and Al concentrated regions minus H0: 0.4 to 4.0 μm, (4) (Perimeter L5 of regions comprised of anchoring oxide layer regions and Al concentrated regions)/(observed area S0): 0.020 to 0.500 μm/μm.sup.2, and (5) (Area S1 of anchoring oxide layer regions)/(observed area S0)≥0.15.

Provided is a grain-oriented electrical steel sheet including a base steel sheet, an intermediate layer which is disposed in contact with the base steel sheet and mainly includes silicon oxide, and an insulation coating which is disposed in contact with the intermediate layer and mainly includes phosphate and colloidal silica, in which the base steel sheet contains predetermined chemical composition, BN having an average particle size of 50 to 300 nm is present, when an emission intensity of B is measured using glow discharge emission analysis, predetermined conditions are satisfied, and a ratio of a major axis to a minor axis of BN is 1.5 or less.

The grain-oriented electrical steel sheet according to the present embodiment is a grain-oriented electrical steel sheet having a base steel sheet (1), an intermediate layer (4) disposed to be in contact with the base steel sheet (1), and an insulation coating (3) disposed to be in contact with the intermediate layer (4). The grain-oriented electrical steel sheet according to the present embodiment includes a surface of the base steel sheet (1) having a strain region (D) which extends in a direction intersecting a rolling direction of the base steel sheet (1), and a crystalline phosphorus oxide M.sub.2P.sub.4O.sub.13 present in the insulation coating (3) on the strain region (D) in a cross-sectional view of a surface parallel to the rolling direction and a sheet thickness direction of the base steel sheet (1). (M means at least one or both of Fe and Cr.)

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 and pickling is conducted after decreasing temperature, an annealing separator applying process where a mass ratio of MgO and Al.sub.2O.sub.3 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, an annealing separator removing process where water-washing is conducted using solution with inhibitor, and an insulation coating forming process where a mass ratio of phosphoric acid and metal compound in insulation coating forming solution is controlled.

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 mixed gas and temperature are controlled for annealing, and an insulation coating forming process where a baking temperature and a heat treatment temperature are controlled.

A grain-oriented electrical steel sheet includes a base steel sheet which contains Si and Mn, an intermediate layer which is disposed on a surface of the base steel sheet and contains a silicon oxide as a main component, and an insulation coating which is disposed on a surface of the intermediate layer. A final-annealed film is not substantially present on a surface of the base steel sheet. In a surface layer region of grain-oriented electrical steel sheet, a Mn-depletion layer having a valley portion of a Mn content in which a Mn content is lower than an average Mn content of the base steel sheet in a region deeper than the surface layer region is provided, and a Mn-rich layer having a peak portion of a Mn content in which a Mn content is higher than that in the valley portion of the Mn content is provided in a region closer to a surface of the insulation coating than the Mn-depletion layer.

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 without hydrogen, and an insulation coating forming process where a baking temperature and a heat treatment temperature are controlled.

A method for producing a grain-oriented electrical steel sheet which has an intermediate layer containing silicon oxide as a main component on a surface of a base steel sheet in which a forsterite film is substantially absent and has an insulation coating on a surface of the intermediate layer includes: a decarburization annealing process of obtaining a decarburization-annealed steel sheet which has the oxygen content or 320 ppm or less and the carbon content of 25 ppm or less by subjecting a cold rolled steel sheet containing Si to decarburization annealing; a final annealing process of heating the decarburization-annealed steel sheet in a state in which a surface of the decarburization-annealed steel sheet is coated with an annealing separator to subject a steel sheet to secondary recrystallization; a removal process of obtaining a finally-annealed steel sheet by removing the annealing separator on the steel sheet which has been subjected to the final annealing process; an intermediate layer forming process of forming the intermediate layer by subjecting the finally-annealed steel sheet to thermal oxidation annealing; and an insulation coating forming process of forming the insulation coating on the finally-annealed steel sheet having the intermediate layer formed thereon.

A grain-oriented electrical steel sheet is a grain-oriented electrical steel sheet which does not have an inorganic coating containing forsterite as a main component and which includes: a base steel sheet containing a prescribed chemical component; a silicon-containing oxide layer provided on the base steel sheet; an iron-based oxide layer provided on the silicon-containing oxide layer; and a tension-insulation coating provided on the iron-based oxide layer, having a thickness of 1 to 3 μm, and containing phosphate and colloidal silica as main components. When the tension-insulation coating undergoes elemental analysis using a glow discharge optical emission spectrometry in a sheet thickness direction from a surface of the tension-insulation coating, a peak Si emission intensity satisfies a prescribed requirement.