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 includes: a base steel sheet having a predetermined chemical composition; a glass coating provided on the surface of the base steel sheet; and a tension-applying insulation coating provided on the surface of the glass coating, in which linear thermal strains having, a predetermined angle (φ) with respect to a transverse direction which is a direction orthogonal to a rolling direction are periodically formed on the surface of the tension-applying insulation coating at predetermined intervals along the rolling direction, a full width at half maximum F1 on the linear thermal strain and a full width at half maximum F2 at an intermediate position between the two linear thermal strains adjacent to each other satisfy 0.00<(F1−F2)/F2≤0.15, the width of the linear thermal strain is 10 μm or more and 300 μm or less, and in the base steel sheet, an orientation distribution angle γ around a rolling direction axis of secondary recrystallization grains, an orientation distribution angle α around an axis parallel to a normal direction, and an orientation distribution angle β around an axis perpendicular to each of the RD axis and the ND axis in units of ° satisfy 1.0≤γ≤8.0 and 0.0≤(α.sup.2+β.sup.2).sup.0.5≤10.0.

Provided is a method for manufacturing a grain-oriented electrical steel sheet. The method comprises: hot rolling a slab to obtain a hot rolled sheet; subjecting the hot rolled sheet to hot band annealing as necessary; subjecting the hot rolled sheet to cold rolling; subjecting the cold rolled sheet to decarburization annealing; applying an annealing separator having MgO as a main component onto a surface of the decarburization annealed sheet and subjecting the decarburization annealed sheet to final annealing to form the forsterite film; and applying an insulating coating treatment liquid onto the final annealed sheet and subjecting the final annealed sheet to flattening annealing to form a tension-applying insulating coating. A difference in total tensions between one and opposite surfaces of the sheet is less than 0.5 MPa. A difference in tensions between the forsterite films in one and opposite surfaces of the sheet is 0.5 MPa or more.

A method for manufacturing a grain-oriented electrical steel sheet according to an aspect of the present invention includes a step of obtaining a hot-rolled steel sheet by carrying out hot rolling on a slab containing a predetermined component composition with a remainder including Fe and impurities, a step of obtaining a hot-rolled annealed sheet by carrying out hot-rolled sheet annealing as necessary, a step of carrying out pickling to obtain a pickled sheet, a step of carrying out cold rolling to obtain a cold-rolled steel sheet, a step of carrying out primary recrystallization annealing, a step of applying an annealing separating agent including MgO to a surface and then carrying out final annealing to obtain a final-annealed sheet, and a step of applying an insulating coating and then carrying out flattening annealing.

A non-oriented electrical steel sheet according to one embodiment of the invention has a chemical composition represented by C: 0.0030% or less, Si: 2.00% or less, Al: 1.00% or less, Mn: 0.10% to 2.00%, S: 0.0030% or less, one or more selected from the group consisting of Mg, Ca, Sr, Ba, Nd, Pr, La, Ce, Zn, and Cd: greater than 0.0100% and not greater than 0.0250% in total, a parameter Q represented by Q=[Si]+2×[Al]−[Mn]: 2.00 or less; Sn: 0.00% to 0.40%, Cu: 0.00% to 1.00%, and a remainder: Fe and impurities, and a parameter R represented by R=(I.sub.100+I.sub.310+I.sub.411+I.sub.521)/(I.sub.111+I.sub.211+I.sub.332+I.sub.221) is 0.80 or greater.

A non-oriented electrical steel sheet according to an embodiment of the present invention includes Ti at 0.0030 wt % or less (excluding 0 wt %), Nb at 0.0035 wt % or less (excluding 0 wt %), V at 0.0040 wt % or less (excluding 0 wt %), B at 0.0003 wt % to 0.0020 wt %, and the remaining portion including Fe and other inevitably added impurities, wherein a value of ([Ti]+0.8[Nb]+0.5[V])/(10*[B]) may be 0.17 to 7.8.

The present invention manufactures a steel sheet for a rotor core for an IPM motor, wherein the steel sheet has a magnetic flux density B.sub.8000 of 1.65 T or more as measured when magnetic field strength is 8000 A/m, and a residual magnetic flux density Br of 0.5 T or more as measured at that time, and optionally, a coercivity Hc of 100 A/m or more as measured after magnetization reaches 8000 A/m. By using the steel sheet manufactured according to the present invention for a rotor core of an IPM motor, it is possible to increase further an output torque in a high-speed rotational range and raise further the maximum rotational speed.

A magnetic core includes a nanocrystalline alloy ribbon having a composition represented by FeCu.sub.xB.sub.ySi.sub.zA.sub.aX.sub.b, where 0.6≤x<1.2, 10≤y≤20, 0≤(y+z)≤24, and 0≤a≤10, 0≤b≤5, all numbers being in atomic percent, with the balance being Fe and incidental impurities, and where A is an optional inclusion of at least one element selected from Ni, Mn, Co, V, Cr, Ti, Zr, Nb, Mo, Hf, Ta and W, and X is an optional inclusion of at least one element selected from Re, Y, Zn, As, In, Sn, and rare earth elements. The nanocrylstalline alloy ribbon has a local structure such that nanocrystals with average particle sizes of less than 40 nm are dispersed in an amorphous matrix and are occupying more than 30 volume percent of the ribbon.

The invention concerns a method for accentuating the orientation of the grains of a continuous steel sheet (1), in particular for producing electrical sheet steel, said method involving, during the movement of the steel sheet (1) in the longitudinal direction of same, a longitudinal stretching of the steel sheet (1) in a stretch region (1d) in which the steel sheet (1) moves at a temperature of between approximately 750° C. and approximately 900° C. The invention also concerns a device for implementing said method in which the stretching is carried out by two tensioning blocks (41, 42) comprising traction rollers arranged to move and guide the steel sheet (1). The invention further concerns a facility for producing electrical sheet steel comprising a line comprising a rolling mill and on which said method and said device are implemented downstream from the rolling mill.

A grain-oriented electrical steel sheet produces reduced noise when worked into a transformer, by setting length d of each plastic strain region in the widthwise direction of the steel sheet to 0.05 mm or more and 0.4 mm or less, and a ratio (Σd/Σw) of a total Σd of the length d to a total Σw of application interval w of each of the above plastic strain regions to 0.2 or more and 0.6 or less.