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.

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 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 grain-oriented electrical steel plate of an exemplary embodiment of the present invention has a groove formed on a surface, wherein a curvature radius RBb at a position where a depth of the groove is maximum is 0.2 μm to 100 μm, and a curvature radius RSb on the groove surface from the position where the depth of the groove is maximum to a quarter-way position of the depth D of the groove is 4 μm to 130 μm.

A grain-oriented electrical steel sheet includes: a chemical composition represented by, in mass %, Si: 2.0% to 5.0%, Mn: 0.03% to 0.12%, Cu: 0.10% to 1.00%, sb or Sn, or both thereof: 0.000% to 0.3% in total, Cr: 0% to 0.3%, P: 0% to 0.5%, Ni: 0% to 1%, and the balance: Fe and impurities, in which an L-direction average diameter of crystal grains observed on a surface of the steel sheet in an L direction parallel to a rolling direction is equal to or more than 3.0 times a C-direction average diameter in a C direction vertical to the rolling direction.

The present invention relates to a composition for forming an insulation coating film of an oriented electrical steel sheet, including a first component (A) including a composite metal phosphate, a derivative thereof, or a mixture thereof, and a second component (B) including at least two colloidal silicas having different average particle diameters, a method for forming an insulation coating film using the same, and an oriented electrical steel sheet having an insulation coating film formed thereon.

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.

Provided are an insulation coating composition for an oriented electrical steel sheet, an oriented electrical steel sheet having an insulation coating formed on the surface thereof by using the same, and a manufacturing method thereof, and specifically, it is possible to provide an insulation coating composition for an oriented electrical steel sheet, including 0.1 to 7 wt % of hollow nanoparticles, 0.1 to 5 wt % of ceramic nanofibers, 0.1 to 5 wt % of mesoporous nanoparticles, 30 to 60 wt % of colloidal silica nanoparticles, and 30 to 60 wt % of phosphate, and to provide an oriented electrical steel sheet including an insulation coating produced by the composition on the surface of the oriented electrical steel sheet, including 0.005 to 0.05 wt % of any one element selected from boron (B), vanadium (V), or a combination thereof, 2.6 to 4.3 wt % of silicon (Si), 0.020 to 0.040 wt % of aluminum (Al), 0.01 to 0.20 wt % of manganese (Mn), in which the balance is composed of Fe and other inevitable impurities, and a manufacturing method thereof.

A non-oriented electrical steel sheet having high magnetic flux density and a low iron loss at a high frequency is produced by subjecting a slab containing, in mass %, C: not more than 0.0050%, Si: 2.8 to 6.5%, Mn: 0.05 to 2.0%, P: not more than 0.10%, S: not more than 0.0050%, Al: 0.3 to 2.0%, N: not more than 0.0050% and Zn: 0.0005 to 0.0050% to a hot rolling, a hot-band annealing, a cold rolling and a finish annealing, a dew point in the hot-band annealing is set to 0 to 70 ° C. and an atmosphere of the finish annealing has a nitrogen content of not more than 30 vol % and a dew point of not higher than −20° C., and a ratio of the amount of nitrogen present as AlN in an entire sheet thickness to the amount of nitrogen present as AlN in a layer from one-side surface of steel sheet to a depth of 1/20 of sheet thickness is made to not less than 5.0.

A process for producing grain-oriented electrical steel strip by means of thin slab continuous casting, comprising the following process steps: a) smelting a steel, b) continuously casting the smelt by thin slab continuous casting, c) heating up the thin slabs and subjecting the slabs to homogenization annealing at a maximum temperature of 1250° C., d) heating to a temperature between 1250° C. and 1350° C., e) continuously hot rolling the thin slabs to form a hot-rolled strip, f) cooling and reeling the hot-rolled strip to form a coil, g) annealing the hot-rolled strip after reeling and prior to a subsequent cold rolling step, h) cold rolling the hot-rolled strip to the nominal usable thickness, i) subjecting the cold-rolled strip to recrystallization, decarburization and nitridation annealing, j) applying an annealing separator (non-stick layer) to the strip surface of the cold-rolled strip, k) subjecting the cold-rolled strip to secondary recrystallization annealing, forming a finished steel strip having a pronounced Goss texture, and l) stress-free annealing the finished steel strip, which has been coated with an insulating layer, provides an improved process for producing grain-oriented electrical steel strip by means of thin slab continuous casting. This is achieved in that the recrystallization, decarburization and nitridation annealing of the cold-rolled strip in process step h) comprises a decarburization annealing phase and a subsequent nitridation annealing phase, with an intermediate reduction annealing phase being interposed between the decarburization annealing phase and the nitridation annealing phase, and carried out at a temperature ranging from 820° C.-890° C., for a maximum period of 40 seconds, with a dry, gaseous annealing atmosphere, which contains nitrogen (N.sub.2) and hydrogen (H.sub.2) and acts on the cold-rolled strip, and which has a water vapor/hydrogen partial pressure ratio pH.sub.2O/pH.sub.2 of less than 0.10.