A grain-oriented electrical steel sheet includes: a base steel sheet including, as a chemical composition, by mass %, C: 0.010% or less, Si: 2.50% to 4.00%, Mn: 0.050% to 1.000%, S+Se: 0.005% or less in total, Sol. Al: 0.005% or less, N: 0.005% or less, Bi+Te+Pb: 0% to 0.0300% in total, Sb: 0% to 0.50%, Sn: 0% to 0.50%, Cr: 0% to 0.50%, Cu: 0% to 1.0%, and a remainder of Fe and impurities; and a tension-applying insulation coating provided on a surface of the base steel sheet, in which, on the surface of the base steel sheet, an arithmetic average roughness Ra along a rolling 90° direction that is a direction perpendicular to a rolling direction is 0.60 μm or less, and when a cross section of the base steel sheet is observed along the rolling 90° direction, recessed parts having a depth of 0.1 μm or more and 2.0 μm or less are present on the surface of the base steel sheet in 1.0/100 μm or more and 6.0/100 μm or less.

A grain-oriented electrical steel sheet according to an aspect of the present invention includes an underlying steel sheet and a tension-insulation coating arranged on the surface of the underlying steel sheet, and a ten-point average roughness RzL in an L direction obtained when the tension-insulation coating is removed from the grain-oriented electrical steel sheet with an alkaline solution, and then the surface of the underlying steel sheet is measured in a rolling direction is 6.0 μm or less.

The 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, including a base steel sheet having a predetermined 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 elemental analysis is performed from a surface of the tension-insulation coating in a sheet thickness direction by glow discharge optical emission spectrometry, predetermined requirements are satisfied.

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.

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.

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 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.

In a base sheet for a grain-oriented electrical steel sheet of the present invention, an amount of surface oxygen x per one surface of the base sheet and a value y of a peak (ΔR/R.sub.0 @1250 cm.sup.−1) of SiO.sub.2 on the surface of the base sheet obtained by infrared reflection spectroscopy satisfy y≥1500x.sup.2.5 and y≥0.24. A method of manufacturing the base sheet for a grain-oriented electrical steel sheet of the present invention includes: adjusting the amount of surface oxygen per one surface of a final-annealed grain-oriented silicon steel sheet to more than 0.01 g/m.sup.2 and 0.05 g/m.sup.2 or less, or more than 0.05 g/m.sup.2 and 0.10 g/m.sup.2 or less; and performing thermal oxidation annealing in an atmosphere in which an oxidation potential represented by a ratio P.sub.H2O/P.sub.H2 of water vapor pressure to hydrogen pressure is 0.0081 or less in a case where the amount of surface oxygen is more than 0.01 g/m.sup.2 and 0.05 g/m.sup.2 or less, or in an atmosphere in which the oxidation potential is 0.005 or less in a case where the amount of surface oxygen is more than 0.05 g/m.sup.2 and 0.10 g/m.sup.2 or less, at a soaking temperature of 1000° C. or lower to form an externally oxidized layer on a surface of the grain-oriented silicon steel sheet.

Provided is a method for manufacturing a grain-oriented electrical steel sheet. The method comprises: hot rolling a slab to obtain a hot rolled sheet; subjecting the hot rolled sheet to hot band annealing as necessary; subjecting the hot rolled sheet to cold rolling; subjecting the cold rolled sheet to decarburization annealing; applying an annealing separator having MgO as a main component onto a surface of the decarburization annealed sheet and subjecting the decarburization annealed sheet to final annealing to form the forsterite film; and applying an insulating coating treatment liquid onto the final annealed sheet and subjecting the final annealed sheet to flattening annealing to form a tension-applying insulating coating. A difference in total tensions between one and opposite surfaces of the sheet is less than 0.5 MPa. A difference in tensions between the forsterite films in one and opposite surfaces of the sheet is 0.5 MPa or more.

A grain-oriented magnetic steel sheet with chromium-free insulating tension coating includes a grain-oriented magnetic steel sheet and an insulating tension coating containing a phosphate salt and silica on a surface of the grain-oriented magnetic steel sheet, the coating further including a crystalline compound represented by the general formula (1): M.sup.II.sub.3M.sup.III.sub.4(X.sup.VO.sub.4).sub.6 . . . (1). A method for producing a grain-oriented magnetic steel sheet with chromium-free insulating tension coating includes applying an insulating tension coating liquid to a surface of a finish annealed grain-oriented magnetic steel sheet, the coating liquid including colloidal silica, a phosphate salt and a metal element M-containing compound in a specific ratio, and heat treating the steel sheet at least one time at a temperature of not less than 900° C. in an atmosphere including a non-oxidizing gas and having a dew point of not more than 0° C.