A grain-oriented electrical steel sheet having excellent iron loss property is produced from a steel slab containing, by mass %, C: 0.002-0.15%, Si: 2.5-6.0%, Mn: 0.01-0.80%, Al: 0.010-0.050% and N: 0.003-0.020%, when: a heating rate between 500-700° C. in decarburization annealing is not less than 80° C./s, a surface roughness Ra of a work roll in final cold rolling is 0.01-3.0 μm, a total content of alkaline earth metals to MgO in annealing separator is 0-5 mass %, an average length L in rolling direction of passed crystal grains is not more than 25 mm, a ratio of crystal grains having a length in rolling direction of not more than 5 mm is 40-90%, and an existence ratio of alkaline earth metal sulfides having a size corresponding to circle of not less than 0.5 μm in a cross section of forsterite film is not more than 0.2/μm per unit length in sheet width direction.

A method for manufacturing a grain-oriented electrical steel sheet, according to an embodiment of the present invention includes: heating a slab, based on 100 wt % of a total composition thereof, including N at 0.0005 wt % to 0.015 wt %, Ti at 0.0001 wt % to 0.020 wt %, V at 0.0001 wt % to 0.020 wt %, Nb at 0.0001 wt % to 0.020 wt %, B at 0.0001 wt % to 0.020 wt %, and the remaining portion including Fe and other impurities, and then hot rolling it to prepare a hot-rolled steel sheet; annealing the hot-rolled steel sheet; after the hot-rolled steel sheet is annealed, cooling the hot-rolled steel sheet, and then cold rolling it to prepare a cold-rolled steel sheet; decarburization-annealing the cold-rolled steel sheet and then nitriding-annealing it, or simultaneously performing the decarburization-annealing and the nitriding-annealing; and final-annealing the decarburization-annealed and nitriding-annealed steel sheet.

A grain-oriented electrical steel sheet that includes a base coating with a high TiN ratio advantageous for the application of tension to the steel sheet and has excellent magnetic property is provided. The grain-oriented electrical steel sheet includes: a base coating having a peak value PTiN of TiN in the form of osbornite, observed in a range of 42°<2θ<43° and a peak value PMg.sub.2SiO.sub.4 of Mg.sub.2SiO.sub.4 in the form of forsterite, observed in a range of 35°<2θ<36° of both more than 0 and satisfying a relationship PTiN≧PMg.sub.2SiO.sub.4, in thin-film X-ray diffraction analysis; and an iron loss W.sub.17/50 of 1.0 W/kg or less.

Provided is an oriented electrical steel sheet including a groove existing on the surface of the electrical steel sheet and a forsterite layer formed on a part or all of the surface of the electrical steel sheet, in which forsterite which is extended from the forsterite layer and penetrates to a base steel sheet in an anchor form is present on the surface of the side of the groove.

Provided is a grain-oriented electrical steel sheet having better transformer iron loss property than conventional grain-oriented electrical steel sheets. A grain-oriented electrical steel sheet comprises: a steel substrate; a forsterite film on a surface of the steel substrate; and a Cr-depleted layer at a boundary between the steel substrate and the forsterite film, the Cr-depleted layer having a Cr concentration that is 0.70 times to 0.90 times a Cr concentration of the steel substrate.

A non-oriented electrical steel sheet according to an embodiment of the present invention includes, in wt%, Si: 2.2 to 4.5 %, Mn: 0.5 % or less (excluding 0 %), AI: 0.001 to 0.5 %, Sn: 0.07 to 0.25 %, and N: 0.0010 to 0.0090 %, and the balance of Fe and inevitable impurities.

A surface layer portion existing in an inner direction from a surface of the steel sheet and a central portion existing inside the surface layer portion are included, and the central portion includes N at 0.005 wt% or less, and the surface layer portion further includes N at 0.001 wt% or more compared to the central portion; and the surface layer portion has an average grain size of 60 .Math.m or less, while the central portion has an average grain size of 70 to 300 .Math.m.

A method for manufacturing a grain-oriented electrical steel sheet according to an embodiment of the present invention comprises the steps of: hot-rolling a slab to prepare a hot-rolled sheet, the slab containing, in wt %, 2.0 to 6.0% of Si, 0.04 to 0.12% of Mn, 0.001 to 0.022% of N, 0.027 to 0.060% of C, 0.01 to 0.08% of Nb, 0.01% or less of Ti, and the balance of Fe and other inevitable impurities; cold-rolling the hot-rolled sheet to prepare a cold-rolled sheet; and subjecting the primarily recrystallization-annealed cold-rolled sheet to secondary recrystallization annealing.

An exemplary embodiment in the present disclosure provides a grain-oriented electrical steel sheet containing, by wt %: 3.0 to 4.5% of Si; 0.05 to 0.2% of Mn; 0.015 to 0.035% of Al; 0.0015% or less (excluding 0%) of C; 0.0015% or less (excluding 0%) of N; 0.0015% or less (excluding 0%) of S; and a balance of Fe and other unavoidable impurities, wherein the grain-oriented electrical steel sheet satisfies the following Relational Expressions 1 and 2:

(W.sub.13/50/W.sub.17/50)≤0.57  [Relational Expression 1]

(W.sub.15/50/W.sub.17/50)≤0.76  [Relational Expression 2] where Wx/y represents a core loss value under conditions in which a magnitude of an applied magnetic field is x/10 T and a frequency is y Hz.

A grain-oriented electrical steel sheet includes: a base steel sheet having a predetermined chemical composition; a glass coating provided on the surface of the base steel sheet; and a tension-applying insulation coating provided on the surface of the glass coating, in which linear thermal strains having, a predetermined angle (φ) with respect to a transverse direction which is a direction orthogonal to a rolling direction are periodically formed on the surface of the tension-applying insulation coating at predetermined intervals along the rolling direction, a full width at half maximum F1 on the linear thermal strain and a full width at half maximum F2 at an intermediate position between the two linear thermal strains adjacent to each other satisfy 0.00<(F1−F2)/F2≤0.15, the width of the linear thermal strain is 10 μm or more and 300 μm or less, and in the base steel sheet, an orientation distribution angle γ around a rolling direction axis of secondary recrystallization grains, an orientation distribution angle α around an axis parallel to a normal direction, and an orientation distribution angle β around an axis perpendicular to each of the RD axis and the ND axis in units of ° satisfy 1.0≤γ≤8.0 and 0.0≤(α.sup.2+β.sup.2).sup.0.5≤10.0.

A grain-oriented electrical steel sheet according to the present invention includes a base steel sheet having plural grooves on a surface and a glass film formed on the surface of the base steel sheet. In case of viewing region including grooves in cross section orthogonal to groove longitudinal direction, a straight line passing through peak point present on profile line of glass film and parallel to groove width direction orthogonal to sheet thickness direction in cross section is defined as reference line, a point present on boundary line between glass film and base steel sheet and present at lowest location in sheet thickness direction is defined as deepest point, and a point present on boundary line and present at the highest location in the sheet thickness direction in region having the deepest point in a center and having length of 2 μm in groove width direction is defined as shallowest point, a relationship between shortest distance A between reference line and deepest point and shortest distance B between reference line and shallowest point satisfies Expression (1).
0.1 μm≤A−B≤5.0 μm  (1)