Provides is a non-oriented electrical steel sheet suitable for use in a rotor of an IPM motor that has excellent magnetic flux density B.sub.50 and high-frequency iron loss properties, high tensile strength and fatigue strength, and little variation in tensile strength. The non-oriented electrical steel sheet has a predetermined steel sheet chemical composition and a microstructure in which a ratio of non-recrystallized microstructure is 5% or more and 70% or less and the number of inclusion having a diameter of 5 μm or more is not more than 5 counts/mm.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.

Provided is a non-oriented electrical steel sheet having an average crystal grain size of crystal grains being not more than 80 μm, an area ratio of crystal grains having a grain size of not less than 1.5 times the average crystal grain size being not less than 10%; and an area ratio of crystal grains having aspect ratios of not more than 0.3 being not more than 20%, by subjecting a steel raw material containing, in mass %, C: not more than 0.005%, Si: 2.0 to 5.0%, Mn: 0.05 to 5.0%, Al: not more than 3.0%, and Zn: 0.0003 to 0.0050% to hot rolling, cold rolling, and cold-rolled sheet annealing and by heating the cold-rolled sheet to an annealing temperature between 700 to 850° C. at the average heating rate between 500 and 700° C. in a heating process of the cold-rolled sheet annealing to be not less than 10° C./s.

A grain-oriented electrical steel sheet according to an embodiment of the present invention may comprise: by weight %, 2.0-4.0% of Si, 0.04-0.2% of Mn, 0.010% or less (exclusive of 0%) of N, 0.01-0.05% of Sb, 0.005% or less (exclusive of 0%) of C, 0.03-0.08% of Sn, 0.01-0.2% of Cr, and the balance of Fe and inevitable impurities; and precipitates which have an average particle size of 5-50 nm and contain at least one of AIN, (Al, Si)N, (Al, Si, Mn)N, Mns, and CuS.

The present invention relates to a non-oriented electrical steel sheet including 1.5 to 4.0 wt % of Si, 0.1 to 1.5 wt % of Al, 0.1 to 1.5 wt % of Mn, 0.005 wt % or less (excluding 0%) of C, 0.005 wt % or less (excluding 0%) of N, 0.005 wt % or less (excluding 0%) of Ti, 0.001 to 0.005 wt % of S, 0.1 wt % or less (excluding 0%) of P, 0.02 to 0.2 wt % of at least one of Sn and Sb, and a balance of Fe and other inevitable impurities; and satisfying the following Formulas 1, 2, and 3.
0.9≤[Al]+[Mn]≤2.1  [Formula 1]
0.2≤([Si]+[Al]+[Mn]/2)*([P]+[Sn]+[Sb])≤0.4  [Formula 2]
(Gs.sub.center−Gs.sub.surface)/(Gs.sub.center*t)≤0.5  [Formula 3] (In Formula 1 and Formula 2, [Al], [Mn], [Si], [P], [Sn], and [Sb] represent the content (weight %) of Al, Mn, Si, P, Sn, and Sb, respectively, and in Formula 3, t represents the thickness (mm) of the non-oriented electrical steel sheet, Gs.sub.surface represents the average grain size (μm) from 0 to t/4 or 3t/4 to t based on the thickness direction of the non-oriented steel sheet, Gs.sub.center represents the average grain size (μm) from more than t/4 to less than 3t/4 based on the thickness direction of the non-oriented steel sheet.)

An oriented silicon steel product with a low iron loss for a low-noise transformer, and manufacturing method thereof are provided. The oriented silicon steel product comprises: a silicon steel substrate, a magnesium silicate bottom layer formed on a surface of the silicon steel substrate, and an insulation coating applied on the magnesium silicate bottom layer. The magnesium silicate bottom layer has a visible light normal reflectivity (R) of 40-60% for. By strictly controlling the visible light normal reflectivity of the magnesium silicate bottom layer of the silicon steel substrate and the evenness of the gloss of magnesium silicate bottom layer, lower iron loss, and reduced magnetostriction can be achieved, and thus a silicon steel product with low noise and particularly suitable for transformers can be obtained.

Grain-oriented electrical steel sheet excellent in magnetic properties and excellent in adhesion of a primary coating to a base steel sheet, an annealing separator utilized for manufacture of grain-oriented electrical steel sheet, and a method for manufacturing grain-oriented electrical steel sheet are proposed. The grain-oriented electrical steel sheet is provided with a base metal steel sheet containing comprising a predetermined chemical composition and a primary coating formed on a surface of the base steel sheet and comprising Mg.sub.2SiO.sub.4 as a main constituent. The primary coating satisfies the conditions of (1) the number density D3 of the Al concentrated region: 0.020 to 0.180/μm.sup.2, (2) (total area S5 of regions which is anchoring oxide layer regions and is also Al concentrated regions)/(total area S3 of Al concentrated regions)≥33%, (3) distance H5 of mean value of length in thickness direction of regions which is anchoring oxide layer regions and is also Al concentrated regions minus H0: 0.4 to 4.0 μm, (4) (total area S1 of anchoring oxide layer regions)/(observed area S0)≥15%.

A non oriented electrical steel sheet includes, as a chemical composition, by mass %, 1.0% or more and 5.0% or less of Si, wherein a sheet thickness is 0.10 mm or more and 0.35 mm or less, an average grain size is 30 μm or more and 200 μm or less, an X1 value defined by X1=(2×B.sub.50L+B.sub.50C)/(3×I.sub.S) is less than 0.845, an E1 value defined by E1=E.sub.L/E.sub.C is 0.930 or more, and an iron loss W.sub.10/1k is 80 W/kg or less.

Disclosed is a non-oriented electrical steel sheet with low magnetic anisotropy, which comprises the following chemical elements in mass percentage: 0<C≤0.005%; Si: 2.0-3.5%; Mn: 0.1-2.0%; at least one of Sn and Sb: 0.003-0.2%; Al: 0.2-1.8%; the balance being Fe and inevitable impurities. Further disclosed is a manufacturing method for the above non-oriented electrical steel sheet with low magnetic anisotropy, which includes the following steps: (1) smelting and casting; (2) hot rolling; (3) normalizing; (4) cold rolling; (5) continuous annealing: rapidly heating a cold-rolled steel sheet from an initial temperature of 350° C.-750° C. to a soaking temperature at a heating rate of 50-800° C./s, and performing soaking and heat preservation; and (6) applying an insulating coating to obtain a finished non-oriented electrical steel sheet. The non-oriented electrical steel sheet is characterized by low iron loss and low magnetic anisotropy at high frequency.

The present disclosure relates to a method for manufacturing a non-oriented electrical steel sheet and the manufactured non-oriented electrical steel sheet, the method including: heating a slab containing, by wt %, 0.005% or less of C, 2.5 to 4.0% or less of Si, 0.1% or less of P, 0.1 to 2.0% of Al, 0.2 to 2.5% of Mn, 0.003% or less of N, 0.005% or less of Ti and Nb, 0.003% or less of S, 0.005 to 0.025% of V, 0.1% or less of Cu, and a balance of Fe and inevitably mixed impurities, and satisfying the following Expression 1; hot-rolling the slab to manufacture a hot-rolled sheet; cold-rolling the hot-rolled sheet to manufacture a cold-rolled sheet; and performing final annealing on the cold-rolled sheet, wherein [Expression 1] is represented by (51*[C])/12−0.002≤[V]≤(51*[C])/12+0.004 (in Expression 1, [C] and [V] represent contents (wt %) of C and V, respectively).