A grain oriented electrical steel sheet includes: a base steel sheet; a glass film which is arranged in contact with the base steel sheet; and an insulation coating which is arranged in contact with the glass film and which includes a phosphate and a colloidal silica as main components. The base steel sheet includes the predetermined chemical composition. A BN whose average particle size is 50 to 300 nm is included at a predetermined number density in a region which is from an interface between the glass film and the insulation coating till 5 μm toward the base steel sheet in a depth direction. A B emission intensity obtained inside the glass film is more than a B emission intensity obtained inside the base steel sheet, when a B emission intensity is measured from a surface of the insulation coating by a glow discharge emission spectroscopy.

Disclosed is a grain-oriented electrical steel sheet capable of obtaining excellent magnetic properties stably over the entire coil length. A grain-oriented electrical steel sheet includes: a chemical composition containing, in mass %, C: 0.005% or less, Si: 2.0% to 4.5%, and Mn: 0.01% to 0.5%, and, in mass ppm, N: 20 ppm or less, each of Se, Te, and O: less than 50 ppm, S: less than 30 ppm, and acid-soluble Al: less than 40 ppm, and Ti: less than 30 ppm, of which 5 ppm or more and 25 ppm or less is acid-soluble Ti, with the balance being Fe and inevitable impurities; and precipitates containing Ti and N with a grain size of 200 nm or more at a frequency of 0.05 grains/mm.sup.2 or more.

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).

A grain oriented electrical steel sheet includes the texture aligned with Goss orientation. In the grain oriented electrical steel sheet, when a grain size RAα.sub.L, a grain size RAβ.sub.L, and a grain size RAγ.sub.L are defined in a rolling direction L, the grain sizes satisfy RAβ.sub.L<RAα.sub.L and RAγ.sub.L<RAα.sub.L.

A grain-oriented electrical steel sheet has a base film composed mainly of forsterite on a surface of the grain-oriented electrical steel sheet and an insulating film containing mainly silicate-phosphate glass which is formed on a surface of the base film, in which, by controlling concentrations of Sr, Ca, and Ba in the base film and the insulating film to have specified gradients, the adhesion property and film tension of the insulating film are improved.

A chemical composition of a base metal of a non-oriented electrical steel sheet contains, by mass %, C: 0.0050% or less, Si: 3.8% to 5.0%, Mn: exceeding 0.2% and less than 2.0%, P: 0.030% or less, S: 0.0030% or less, Al: 0.005% or more and less than 0.050%, N: 0.0005% to 0.0030%, Ti: less than 0.0050%, Nb: less than 0.0050%, Zr: less than 0.0050%, V: less than 0.0050%, Cu: less than 0.20%, Ni: less than 0.50%, Sn: 0% to 0.10%, Sb: 0% to 0.10%, a remainder: Fe and impurities. [Si+0.5×Mn≥4.3] is satisfied and the average grain size of the base metal is in a range of 10 to 80 μm.

Provided is a non-oriented electrical steel sheet that contains substantially no Al and contains large amounts of Si and Mn and has low iron loss, comprising a chemical composition containing C: 0.0050% or less, Si: 2.0% or more and 6.0% or less, Mn: 1.0% or more and 3.0% or less, P: 0.20% or less, S: 0.0050% or less, N: 0.0050% or less, Al: 0.0050% or less, and one or more selected from B: 0.0001% or more and 0.0050% or less, Nb: 0.0001% or more and 0.0050% or less, and V: 0.0005% or more and 0.0500% or less, with a balance consisting of Fe and inevitable impurities, wherein a number density of Si—Mn nitrides with an average diameter of 50 nm or more and 500 nm or less is 1 or less per μm.sup.3.

A non-oriented electrical steel sheet including a base metal that has a chemical composition including, in mass%, C: 0.0010 to 0.0040%, Si: 4.0 to 5.0%, Mn: 0.20% or less Al: 0.010% or more and less than 0.050%, P: 0.030% or less, S: 0.0030% or less, N: 0.0005 to 0.0030%, O: 0.0100 to 0.0400%, Ca: less than 0.0010%, Ti: less than 0.0050%, Nb: less than 0.0050%, Zr: less than 0.0050%, V: less than 0.0050%, Cu: less than 0.20%, Ni: less than 0.50%, Sn: 0 to 0.05%, Sb: 0 to 0.05%, and a balance: Fe and impurities, in which the base metal has an O content of less than 0.0050% in a region excluding a portion from a surface of the base metal to a position of 10 .Math.m in a depth direction of the base metal.

A non-oriented electrical steel sheet including a base metal that has a chemical composition including, in mass %, C: 0.0010 to 0.0040%, Si: 3.5 to 4.9%, Mn: 0.05 to 0.20%, Al: 0.05 to 0.45%, P: 0.030% or less, S: 0.0030% or less, N: 0.0030% or less, O: 0.0100 to 0.0400%, Ca: less than 0.0010%, Ti: less than 0.0050%, Nb: less than 0.0050%, Zr: less than 0.0050%, V: less than 0.0050%, Cu: less than 0.20%, Ni: less than 0.50%, Sn: 0 to 0.05%, Sb: 0 to 0.05%, and a balance: Fe and impurities, and satisfying [4.0≤Si+Al≤5.0], in which the base metal has an O content of less than 0.0050% in a region excluding a portion from a surface of the base metal to a position of 10 μm in a depth direction of the base metal.

Disclosed is a low-cost non-oriented electrical steel plate with an extremely low aluminum content, which plate comprises the following chemical elements in percentage by mass: 0.003% or less of C, 0.1%-1.2% of Si, 0.1%-0.4% of Mn, 0.01%-0.2% of P, 0.003% or less of S, 0.001% or less of Al, 0.003%-0.01% of O, 0.003% or less of N, and 0.005%-0.05% of Sn, with the condition Si.sup.2/P: 0.89-26.04 being satisfied. In addition, further disclosed is a method for manufacturing the non-oriented electrical steel plate. The method comprises steps of: (1) smelting; (2) continuous casting; (3) hot rolling: wherein a hot rolled plate is subjected to soaking and heat preservation by means of residual heat of hot rolled steel coils, rather than being subjected to normalizing treatment or cover furnace annealing after coiling; (4) primary cold rolling; and (5) continuous annealing. In the non-oriented electrical steel plate of the present invention, reasonable chemical ingredients and process designs are used, and the non-oriented electrical steel plate not only has excellent economy, but also has the properties of high magnetic induction and low iron loss.