An annealing separator composition for a grain-oriented electrical steel sheet according to an exemplary embodiment of the present invention contains a composite metal oxide containing Mg and a metal M, wherein the metal M is one or more of Be, Ca, Ba, Sr, Sn, Mn, Fe, Co, Ni, Cu, and Zn.

A non-oriented electrical steel sheet according to an exemplary embodiment of the present invention includes, in wt%, Si: 1.5 to 4.0%, Al: 0.5 to 1.5%, Mn: 0.05 to 0.55%, C: 0.005% or less, Ti: 0.004% or less (excluding 0%), N: 0.005% or less (excluding 0%), S: 0.005% or less (excluding 0%), and Cu: 0.01% or less (excluding 0%), and the balance of Fe and inevitable impurities, and satisfies Formula 1 and Formula 2 below.

[N]≤0.005×([Al]×[Ti])  [Formula 1]

[S]≤0.01×([Mn]+[Cu])  [Formula 2]

(In Formula 1 and Formula 2, [N], [Al], [Ti], [S], [Mn], and [Cu] represent a content (wt %) of N, Al, Ti, S, Mn, and Cu, respectively).

An embodiment of the present invention provides a non-oriented electrical steel sheet including. in wt%: Si: 2.5 to 4.0 %, Mn: 0.1 to 1.0 %, Al: 0.5 to 1.5 %, P: 0.002 to 0.015 %, and As: 0.002 to 0.01 %, and the balance of Fe and inevitable impurities, and satisfying Formula 1 and Formula 2.

[00001]$0.005\le \left(\left[\text{P}\right]+\left[\text{As}\right]\right)\le 0.015$

(In Formula 1, [P] and [As] represent a content (wt%) of P and As, respectively.)

[00002]$\left[\text{STD}\right]\le 0.7\times \left[\text{GS}\right]$

([GS] is an average grain size (.Math.m) measured when 10,000 or more grains having a grain size of 5 to 500 .Math.m are observed on a surface of the steel sheet, and STD is a standard deviation (.Math.m) at that time.)

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.

An object of the present invention is to provide magnesium oxide for an annealing separator which is useful for obtaining grain-oriented electromagnetic steel sheets with excellent magnetic properties and insulating properties. To resolve the above object, an aspect of the present invention resides in magnesium oxide for an annealing separator having a sulfur content of 0.1 to 0.5 mass % and an aggregation degree R.sub.Blaine/R.sub.BET of 3.0 to 5.5 wherein R.sub.Blaine is the particle size calculated from the Blaine specific surface area and R.sub.BET is the particle size calculated from the BET specific surface area.

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.

An object of the present invention is to provide magnesium oxide for an annealing separator which is useful for obtaining grain-oriented electromagnetic steel sheets with excellent magnetic properties and insulating properties. To resolve the above object, an aspect of the present invention resides in magnesium oxide for an annealing separator which has a BET specific surface area of 12.0×10.sup.3 to 25.0×10.sup.3 m.sup.2.Math.kg.sup.−1 and a Blaine specific surface area of 2.0×10.sup.3 to 7.0×10.sup.3 m.sup.2.Math.kg.sup.−1.

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.