A non-oriented electrical steel sheet according to an embodiment of the present invention includes, in wt %, C at 0.005% or less (excluding 0%), Si at 0.5 to 2.4%, Mn at 0.4 to 1.0%, S at 0.005% or less (excluding 0%), Al at 0.01% or less (excluding 0%), N at 0.005% or less (excluding 0%), Ti at 0.005% or less (excluding 0%), Cu at 0.001 to 0.02%, and the balance of Fe and inevitable impurities, and satisfies Formula 1 below, wherein a volume fraction of grains in which an angle formed by a {111} surface and a rolling surface of the steel sheet is 15° or less is 27% or more.

[Mn]/([Si]+150×[Al])≤0.35   [Formula 1]

(In Formula 1, [Mn], [Si], and [Al] are contents (wt %) of Mn, Si, and Al, respectively.)

Grain-oriented electrical steel sheet excellent in magnetic properties and excellent in adhesion of the primary coating to the steel sheet is provided. This is provided with a base metal steel sheet containing a predetermined chemical composition and a primary coating formed on a surface of the base metal steel sheet and containing Mg.sub.2SiO.sub.4 as a main constituent. A peak position of Al emission intensity obtained when performing elemental analysis by glow discharge optical emission spectrometry from a surface of the primary coating in a thickness direction of the grain-oriented electrical steel sheet is arranged within a range of 2.0 to 10.0 μm from the surface of the primary coating in the thickness direction. A number density of Al oxides of a size of 0.2 μm or more in terms of a circle equivalent diameter based on the area at the peak position of Al emission intensity is 0.032 to 0.20/μm.sup.2, and, in a 100 μm×100 μm distribution chart of Al oxides at the peak position of Al emission intensity obtained by glow discharge optical emission spectrometry, if dividing the distribution chart by 10 μm×10 μm grid section, a ratio of a number of grid sections not containing the Al oxides to the total number of grid sections in the distribution chart is 5% or less.

Grain-oriented electrical steel sheet having an aluminum borate coating able to impart larger tension that the past and a method for manufacturing grain-oriented electrical steel sheet are formed. The grain-oriented electrical steel sheet according to the present invention has a steel sheet and an insulating coating formed on the steel sheet and containing aluminum and boron, where the oxides contain crystalline oxides and a maximum value of an emission intensity ratio of boron with respect to aluminum at an interface between the insulating coating and the steel sheet, analyzed by glow discharge optical emission spectrometry, is 2.5 times or more and 4.0 times or less of the emission intensity ratio of boron with respect to aluminum in the insulating coating.

A grain oriented electrical steel sheet has a magnetic domain structure modified by strain introduction without a trace of treatment, in which noise generated when the grain oriented electrical steel sheet is used laminated on an iron core of a transformer is effectively reduced by: setting a magnetic flux density B.sub.8 to 1.92 T or higher; then setting a ratio of average magnetic domain width of treated surface after strain-introducing treatment W.sub.a to average magnetic domain width before strain-introducing treatment W.sub.0 as W.sub.a/W.sub.0<0.4; and setting a ratio of W.sub.a to average magnetic domain width of untreated surface W.sub.b as W.sub.a/W.sub.b>0.7; and further setting a ratio of average width of magnetic domain discontinuous portion W.sub.d in the untreated surface to average width of magnetic domain discontinuous portion in treated surface resulting from strain-introducing treatment W.sub.c as W.sub.d/W.sub.c>0.8; and setting W.sub.c<0.35 mm.

A grain oriented electrical steel sheet is subjected to a temperature holding treatment at a temperature T of 250-600° C. for 1-10 seconds in the primary recrystallization annealing and heated from temperature T to 700° C. at not less than 80° C./s and from 700° C. to a soaking temperature at not more than 15° C./s, wherein an oxygen potential from 700° C. to the soaking temperature is 0.2-0.4 and an oxygen potential during the soaking is 0.3-0.5 and an area ratio of secondary recrystallized grains is not less than 90% when an angle α deviated from {110}<001> ideal orientation is less than 6.5° and an area ratio is not less than 75% when a deviation angle is less than 2.5° and an average length [L] in the rolling direction is not more than 20 mm and an average value [β] of the angle β is 15.63×[β]+[L]<44.06.

A method for refining a magnetic domain of a grain-oriented electrical steel strip is provided, including a steel strip supporting roll position adjusting step of controlling a position of the steel strip in a vertical direction while supporting the steel strip proceeding along a production line, a laser irradiating step of forming a groove on a surface of the steel strip by irradiating a laser beam onto the surface of the steel strip to melt the steel strip, and a detecting step of detecting a defect in the groove formed on the surface of the steel strip while the steel strip proceeds, so as to be able to detect whether the groove is defective by confirming a machining state of a magnetic domain refined groove formed on the surface of the steel strip in a working process.

An embodiment of the present invention provides a non-oriented electrical steel sheet, including Si at 2.0 to 4.0 wt %, Al at 1.5 wt % or less (excluding 0 wt %), Mn at 1.5 wt % or less (excluding 0 wt %), Cr at 0.01 to 0.5 wt %, V at 0.0080 to 0.015 wt %, C at 0.015 wt % or less (excluding 0 wt %), N at 0.015 wt % or less (excluding 0 wt %), and the remainder including Fe and other impurities unavoidably added thereto.
0.004≤([C]+[N])≤0.022  [Equation 1] (In Equation 1, [C] and [N] represent a content (wt %) of C and N, respectively.)

Ferritic stainless steel is characterized by including, by mass %: Cr: 12.0% to 16.0%; C: 0.020% or less; Si: 2.50% or less; Mn: 1.00% or less; P: 0.050% or less; S: 0.0030% or less; Al: 2.50% or less; N: 0.030% or less; Nb: 0.001% to 1.00%; one or more of B: 0.0200% or less, Sn: 0.20% or less, Ga: 0.0200% or less, Mg: 0.0200% or less, and Ca: 0.0100% or less; and a balance consisting of Fe and impurities, in which Expression (1) is satisfied.
10(B+Ga)+Sn+Mg+Ca>0.020  (1)

A nitrided steel member including an iron nitride compound layer formed on a surface of a steel member having predetermined components, wherein: in X-ray diffraction peak intensity IFe.sub.4N (111) of a (111) crystal plane of Fe.sub.4N and X-ray diffraction peak intensity IFe.sub.3N (111) of a (111) crystal plane of Fe.sub.3N, which are measured on a surface of the nitrided steel member by X-ray diffraction, an intensity ratio expressed by IFe.sub.4N (111)/{IFe.sub.4N (111)+IFe.sub.3N (111)} is 0.5 or more; Vickers hardness of the iron nitride compound layer is 900 or less, Vickers hardness of a base metal immediately under the iron nitride compound layer is 700 or more, and a difference between the Vickers hardness of the iron nitride compound layer and the Vickers hardness of the base metal is 150 or less; and a thickness of the iron nitride compound layer is 2 to 17 μm.

A grain-oriented electrical steel sheet includes a plurality of linear deformable portions formed on a surface of the electrical steel sheet in a rolling direction, wherein an interval between the deformable portions changes to correspond to a grain size of grains over the entire length of the steel sheet, and at least two regions in which intervals between the deformable portions are different exist.