Methods for producing non-oriented electrical steel sheets comprising steps including hot rolling a slab having a chemical composition comprising C: not more than 0.01 mass %, Si: not more than 6 mass %, Mn: 0.05-3 mass %, P: not more than 0.2 mass %, Al: not more than 2 mass %, N: not more than 0.005 mass %, S: not more than 0.01 mass %, Ga: not more than 0.0005 mass %, and the remainder being Fe and inevitable impurities, pickling without conducting hot band annealing or after conducting hot band annealing or self-annealing, subjecting to one or more cold rollings including an intermediate annealing therebetween and a finish annealing, and forming an insulation coating, an average heating rate from 500 to 800° C. in the heating process of the finish annealing is not less than 50° C./s, whereby a non-oriented electrical steel sheet having excellent magnetic properties is obtained even if hot band annealing is omitted.

A grain-oriented electrical steel sheet according to an embodiment of the prevent invention comprises: Si: 1.0% to 7.0%, C: 0.005% or less (excluding 0%), P: 0.0010 to 0.1%, Sn: 0.005 to 0.2%, S: 0.0005 to 0.020%, Se: 0.0005 to 0.020% and B: 0.0001 to 0.01% by weight, and the remainder comprising Fe and other inevitable impurities.

A motor comprising a steel sheet used as a core material of the motor, wherein the steel sheet includes a composition including: by mass %, 0.010% or less of C; 2.0% to 7.0% of Si; 2.0% or less of Al; 0.05% to 1.0% of Mn; 0.005% or less of S; 0.005% or less of N; and balance Fe and inevitable impurities; the steel sheet includes a magnetic flux density changing area where a change ΔB in magnetic flux density to a change ΔH=50 A/m in a magnetic field, is equal to or higher than 0.50 T; a thickness of the steel sheet is 0.05 mm to 0.20 mm; and an eddy-current loss of the steel sheet, at 1000 Hz−1.0 T, is equal to or less than 0.55 of a total iron loss.

In the production of a non-oriented electrical stress sheet by hot rolling a slab having a chemical composition comprising, by mass %, C: not more than 0.005, Si: 1.5-6.0, Mn: 0.05-2.0 and P: 0.03-0.15, subjecting to a hot band annealing, if necessary, cold rolling, finish annealing, and forming an insulation coating, the cooling from 700 C. to 500 C. in the finish annealing is conducted in an oxidizing atmosphere with an oxygen potential P.sub.H2O/P.sub.H2 of not less than 0.001 for 1-300 seconds, whereby P is segregated into the surface of the steel sheet after the finish annealing to obtain a non-oriented electrical steel sheet enhancing a crystal grain growth properties in the stress relief annealing.

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 (r) 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 Fl 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<(F1F2)/F20.15, the width of the linear thermal strain is 10 m or more and 300 m, or less, and in the base steel sheet, an orientation distribution angle around a rolling direction axis of secondary recrystallization grains, an orientation distribution angle around an axis parallel to a normal direction. and an orientation distribution angle around an axis perpendicular to each of the RD axis and the ND axis in units of satisfy 1.08.0 and 0.0(.sup.2+.sup.2).sup.0.510.0.

A grain-oriented electrical steel sheet includes: a base steel sheet including, as a chemical composition, by mass %, C: 0.010% or less, Si: 2.50% to 4.00%, Mn: 0.050% to 1.000%, S+Se: 0.005% or less in total, Sol. Al: 0.005% or less, N: 0.005% or less, Bi+Te+Pb: 0% to 0.0300% in total, Sb: 0% to 0.50%, Sn: 0% to 0.50%, Cr: 0% to 0.50%, Cu: 0% to 1.0%, and a remainder of Fe and impurities; and a tension-applying insulation coating provided on a surface of the base steel sheet, in which, on the surface of the base steel sheet, an arithmetic average roughness Ra along a rolling 90 direction that is a direction perpendicular to a rolling direction is 0.60 m or less, and when a cross section of the base steel sheet is observed along the rolling 90 direction, recessed parts having a depth of 0.1 m or more and 2.0 m or less are present on the surface of the base steel sheet in 1.0/100 m or more and 6.0/100 m or less.

A method for manufacturing a grain-oriented electrical steel sheet including a step of hot-rolling a slab containing a predetermined component composition with a remainder including Fe and an impurity to obtain a hot-rolled steel sheet, a step of, after carrying out hot-rolled steel sheet annealing on the hot-rolled steel sheet, carrying out cold rolling to obtain a cold-rolled steel sheet, a step of carrying out primary recrystallization annealing including a rapid temperature increase at an average temperature increase velocity V of 400 C./s or more and imparting of a steel sheet tensile force S on the cold-rolled steel sheet, and a step of applying an annealing separating agent to a surface of the cold-rolled steel sheet after the primary recrystallization annealing and then carrying out flattening annealing.

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.

Provided are a grain-oriented electrical steel sheet with low iron loss even when including at least one grain boundary segregation element among Sb, Sn, Mo, Cu, and P, and a method for manufacturing the same. In our method, Pr is controlled to satisfy Pr0.075T+18, where T>10, 5<Pr, T (hr) is the time required after final annealing to reduce the temperature of a secondary recrystallized sheet from 800 C. to 400 C., and Pr (MPa) is the line tension on the secondary recrystallized sheet during flattening annealing. As a result, a grain-oriented electrical steel sheet in which iron loss is low and a dislocation density near crystal grain boundaries of the steel substrate is 1.010.sup.13 m.sup.2 or less can be obtained even when the grain-oriented electrical steel sheet contains at least one of Sb, Sn, Mo, Cu, and P.

Disclosed is a non-oriented electrical steel sheet that is low in iron loss and exhibits excellent magnetic properties even when subjected to final annealing at high temperature. The non-oriented electrical steel sheet can be obtained from a steel (low-Al steel) having a chemical composition containing, in mass %, C: 0.005% or less, Si: 1.0% to 4.5%, Mn: 0.02% to 2.0%, Sol. Al: 0.001% or less, P: 0.2% or less, S+Se: 0.0010% or less, N: 0.005% or less, O: 0.005% or less, and Cu: 0.02% to 0.30%, and the balance consisting of Fe and incidental impurities.