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 HO: 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/μ.sup.2, and (5) (Area S1 of anchoring oxide layer regions)/(observed area S0)≥0.15.

A grain-oriented electrical steel sheet having a metallographic structure after secondary-recrystallized annealing including matrix grains of Goss-oriented secondary recrystallized grains, wherein an existence frequency of Goss-oriented crystal grains having a major diameter of 5 mm or less in the matrix grains is 1.5 grains/cm.sup.2 or more and 8 grains/cm.sup.2 or less, and the magnetic flux density B8 is 1.88 T or more, and wherein deviation angles from a rolling direction of [001] direction of the Goss-oriented crystal grains having the major diameter of 5 mm or less are 7″ or less and 5° or less, in terms of a simple or arithmetic average of α angle and β angle, respectively, wherein the α angle represents an angle formed by a longitudinal direction and a projection of the [001] on a specimen surface, and the β angle represents a tilt of the [001] out of the specimen surface.

A grain oriented electrical steel sheet includes the texture aligned with Goss orientation. In the grain oriented electrical steel sheet, when (α.sub.1 β.sub.1 γ.sub.1) and (α.sub.2 β.sub.2 γ.sub.2) represent deviation angles of crystal orientations measured at two measurement points which are adjacent on the sheet surface and which have an interval of 1 mm, the boundary condition BA is defined as |γ.sub.2−γ.sub.1|≥0.5°, and the boundary condition BB is defined as [(α.sub.2−α.sub.1).sup.2+(β.sub.2−β.sub.1).sup.2+(γ.sub.2−γ.sub.1).sup.2].sup.1/2≥2.0°, the boundary which satisfies the boundary condition BA and which does not satisfy the boundary condition BB is included.

A non-oriented electrical steel sheet produced by hot-rolling a steel slab containing Si: 2.8 to 6.5 mass % and Zn: 0.0005 to 0.0050 mass % followed by cold rolling and finish annealing, a coating agent containing at least one element from Sn, Sb, P, S, Se, As, Te, B, Pb, and Bi is applied to the surface after annealing forming an insulation coating with nitriding-suppressing ability. Alternatively, an intermediate layer containing at least one element from Sn, Sb, P, S, Se, As, Te, B, Pb, and Bi and having a nitriding-suppressing ability forms on the steel sheet iron matrix after the annealing and forms an insulation coating, without above elements, on the intermediate layer thus obtaining a non-oriented electrical steel sheet wherein a high strength rotor core with and stator core with excellent magnetic is simultaneously obtained, and a motor core including a stator core and rotor core from the steel sheet.

In a production of a non-oriented electrical steel sheet by hot-rolling a steel slab containing Si: 2.8 to 6.5 mass % and Zn: 0.0005 to 0.0050 mass % followed by cold rolling and finish annealing, a coating agent containing at least one element selected from Sn, Sb, P, S, Se, As, Te, B, Pb, and Bi is applied to the steel sheet surface after the finish annealing to form an insulation coating with a nitriding-suppressing ability. Alternatively, an intermediate layer containing at least one element selected from Sn, Sb, P, S, Se, As, Te, B, Pb, and Bi and having a nitriding-suppressing ability is formed on the steel sheet iron matrix after the finish annealing and form an insulation coating not containing above elements is formed on the intermediate layer thus to obtain a non-oriented electrical steel sheet from which a rotor core with high strength and stator core with excellent magnetic properties after the stress-relief annealing can be obtained at the same time, and a motor core comprising a stator core and rotor core is produced from the steel sheet.

An annealing separator for an oriented electrical steel sheet includes: a first component including a Mg oxide or a Mg hydroxide; and a second component including one kind among oxides and hydroxides of a metal selected from Al, Ti, Cu, Cr, Ni, Ca, Zn, Na, K, Mo, In, Sb, Ba, Bi, and Mn, or two or more kinds thereof.

Provided is an oriented electrical steel sheet including: a forsterite film formed on one side or both sides of an oriented electrical steel sheet substrate; and a ceramic layer formed on an entire or partial region of the forsterite film. Provided is a manufacturing method for an oriented electrical steel sheet including: preparing an oriented electrical steel sheet having a forsterite film formed on one surface or both surfaces thereof; and forming a ceramic layer by spraying ceramic powder on the forsterite film.

Grain-oriented electrical steel sheet excellent in magnetic properties and excellent in adhesion of a primary coating to the steel sheet is provided. The grain-oriented electrical steel sheet is provided with a base steel sheet having a chemical composition containing C: 0.005% or less, Si: 2.5 to 4.5%, Mn: 0.050 to 1.000%, a total of S and Se: 0.005% or less, sol. Al: 0.005% or less, and N: 0.005% or less and having a balance of Fe and impurities and a primary coating having Mg.sub.2 SiO.sub.4 as a main constituent formed on a surface of the base steel sheet. A peak position of Al emission intensity obtained when conducting elemental analysis by glow discharge spectrometry from a surface of the primary coating in a thickness direction is present in a range of 2.0 to 12.0 μm from a surface of the primary coating to the thickness direction. A sum of perimeters of the Al oxides at the peak position of Al emission intensity is 0.20 to 1.00 μm/μm.sup.2, and a number density of Al oxides is 0.02 to 0.20/μm.sup.2.

A grain-oriented electrical steel sheet according to an embodiment of the present invention has an average degree of orientation difference of 0.5 to 10° between recrystallized grains that are in contact with a groove present on the surface of the electrical steel sheet and the bottom of the groove, and other recrystallized grains.

A grain-oriented electrical steel sheet according to an exemplary embodiment of the present invention includes: a linear groove formed in one or both surfaces of the electrical steel sheet in a direction intersecting with a rolling direction; and a linear thermal shock portion formed in the one or both surfaces of the electrical steel sheet in a direction intersecting with the rolling direction. An angle between a longitudinal direction of the groove and a longitudinal direction of the thermal shock portion is 1 to 5°.

A preparation method of glassless grain-oriented silicon steel includes the following operations. During a decarburization annealing, a thickness of an oxide film on a surface of strip is 1.5-2.5 μm; an atomic weight ratio of Si element and Fe element in the oxide film satisfies: Si/(Si+Fe)≥0.76; during a high-temperature annealing, a cooling stage includes sequentially: cooling with an inner cover when a temperature drops from 1200° C. to 500° C.; wherein a protective gas is a mixed gas containing nitrogen and hydrogen, and a volume percentage of the hydrogen in the mixed gas is >3%; cooling with the inner cover when the temperature drops from 500° C. to 200° C.; wherein the protective gas is nitrogen; and cooling in air by removing the inner cover when the temperature is <200° C.