In a production of a grain-oriented electrical steel sheet comprising hot rolling a raw steel material, cold rolling, decarburization annealing, applying an annealing separator composed mainly of MgO, finish annealing and magnetic domain subdividing, the annealing separator including certain compounds, and the finish annealing conducted by holding the steel sheet at a temperature of 800 to 950? C. for 10 to 100 hours and passing a dry gas containing not less than 1 vol % of H.sub.2 and having a dew point of not higher than 10? C. to reach a furnace pressure of not less than 3.5 mmH.sub.2O from not lower than 1050? C. to a purification treatment temperature, so that a pickling weight loss of undercoat film by pickling with HCl is not more than 1.8 g/m.sup.2 and the total concentration of Sn, Sb, Mo, and W on a boundary face between the film and iron matrix is 0.01 to 0.15 mass %.

This wound core is a wound core including a wound core main body obtained by stacking a plurality of polygonal annular grain-oriented electrical steel sheets in a side view, and the grain-oriented electrical steel sheet has planar portions and bent portions that are alternately continuous in a longitudinal direction, and in at least one bent portion, the crystal grain size Dpx (mm) of the grain-oriented electrical steel sheet is FL/4 or more. Here, FL the an average length (mm) of the planar portions.

Provided is a grain-oriented electrical steel sheet that can benefit from the iron loss improving effect by groove formation while effectively suppressing a decrease in magnetic flux density. A grain-oriented electrical steel sheet comprises predetermined linear grooves, wherein in each linear groove, a proportion of predetermined flat portions to an entire length of the linear groove is 30% or more and 90% or less, the number of flat portions each of which is continuous for a predetermined length is 10 or more per 100 cm.sup.2 surface area, and a ratio of ten-point average roughness Rzjis to average depth D is 0.1 or more and 1 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.)

Vibration of an iron core is reduced to reduce transformer noise. An iron core for a transformer comprises a plurality of grain-oriented electrical steel sheets stacked together, wherein at least one of the plurality of grain-oriented electrical steel sheets: (1) has a region in which closure domains are formed in a direction crossing a rolling direction and a region in which no closure domains are formed; and (2) has an area ratio R of 0.10% to 30%, the area ratio R being an area ratio, to the whole grain-oriented electrical steel sheet, of a region in which a shrinkage amount at a maximum displacement point when excited in the rolling direction at a maximum magnetic flux density of 1.7 T and a frequency of 50 Hz is at least 2?10.sup.?7 less than a shrinkage amount in the region in which no closure domains are formed.

Vibration of an iron core is reduced to reduce transformer noise. An iron core for a transformer comprises a plurality of grain-oriented electrical steel sheets stacked together, wherein at least one of the plurality of grain-oriented electrical steel sheets: (1) has a region in which closure domains are formed in a direction crossing a rolling direction and a region in which no closure domains are formed; (2) has an area ratio R.sub.0 of 0.10% to 3.0%, the area ratio R.sub.0 being defined as a ratio of S.sub.0 to S; and (3) has an area ratio R.sub.1a of 50% or more, the area ratio R.sub.1a being defined as a ratio of S.sub.1a to S.sub.1.

An Fe-based amorphous alloy ribbon reduced in iron loss, less deformed, and highly productive in a condition of a magnetic flux density of 1.45 T is provided. One aspect of the present disclosure provides an Fe-based amorphous alloy ribbon having first and second surfaces, and is provided with continuous linear laser irradiation marks on at least the first surface. Each linear laser irradiation mark is formed along a direction orthogonal to a casting direction of the Fe-based amorphous alloy ribbon, and has unevenness on its surface. When the unevenness is evaluated in the casting direction, a height difference HL?width WA calculated from the height difference between a highest point and a lowest point in a thickness direction of the Fe-based amorphous alloy ribbon and the width WA which is a length of the linear irradiation mark on the first surface is 6.0 to 180 ?m.sup.2.

A grain-oriented electrical steel sheet according to an exemplary embodiment of the present invention incudes a groove formed on a surface and a solidified alloy layer formed under the groove, wherein the solidified alloy layer includes recrystallized particles of which an average particle diameter is 1 to 8 m.

Provided is a grain-oriented electrical steel sheet including a steel sheet having a steel sheet surface in which a groove, which extends in a direction intersecting a rolling direction and of which a groove depth direction matches a sheet thickness direction, is formed. When an average value of a groove depth in a sheet thickness direction at a central portion of the groove in a longitudinal groove direction is set as an average groove depth D, a straight line, which connects a first point at which a groove depth in the sheet thickness direction becomes 0.05D and a second point at which the groove depth becomes 0.50D, at an inclined portion of the groove is set as a groove end straight line, an angle made by the steel sheet surface and the groove end straight line is set as a first angle , and an average value of a groove-width-direction length, which is a length of a line segment connecting two points at which a groove depth in the sheet thickness direction in a contour of the groove on the groove-width-direction cross-section becomes 0.05D, is set as an average groove width W, an aspect ratio A obtained by dividing the average groove depth D by the average groove width W, and the first angle satisfy the following Expression (1).
<21A+77(1)

A method of manufacturing a stator is provided. The method may include stamping steel into laminations each having an inner edge area defining a residual stress associated with a magnetic permeability. The method may also include exposing the laminations to a changing magnetic field such that, for each of the laminations, a density of resulting eddy currents is greatest near the inner edge area to heat the same relative to central areas of the lamination to decrease the residual stress and core loss.