Abstract: Grain oriented silicon steel sheet on which is formed an insulating coating having a thickness that is not less than 2.5 .mu.m that imparts tension to the steel sheet which does not have an inorganic mineral layer formed during a final annealing step (glass film) and a method of forming on grain oriented silicon steel sheet an insulating coating that is not less than 2.5 .mu.m thick and which imparts tension to the steel sheet which does not have the inorganic mineral layer (glass film) that forms during finish annealing, and a method of forming a tensioning insulating coating on grain oriented silicon steel sheet which has been finish annealed and does not have an inorganic mineral surface layer (glass film), after first forming a layer of SiO.sub.2 not less than 0.001 .mu.m thick on the oriented silicon steel sheet.

Abstract: In a process for the preparation of oriented electrical steel sheet having a high magnetic flux density a primary recrystallization annealed steel sheet is nitrided for a short period of time in a temperature range of 800.degree. C. or less whereby growth of crystal grains does not substantially occur. The nitrided sheet is held at a temperature range of 700.degree. C. to 800.degree. C. for at least four hours during temperature raising to final annealing temperature whereby nitride formed by the nitriding dissolves and re-precipitates allowing the nitride to transform to a thermally stable nitride containing aluminium.

Abstract: In order to provide a very low iron loss, it is necessary to render the surface of a steel sheet smooth (specular). In the present invention, this is effected in a finish annealing furnace to simultaneously attain a high magnetic flux density and a specular surface. Specifically, after the completion of decarburization annealing, a steel material is pickled to remove an oxide layer present on the surface of the steel sheet, coated with an annealing separator comprising a substance nonreactive or less reactive with SiO.sub.2 and then subjected to finish annealing to provide a grain oriented electrical steel sheet having a specular surface. Magnetic domain division and tension coating of the steel sheet can provide a low iron loss value. In the finish annealing, since no time is required for dehydration, the annealing time can be shortened.

Abstract: A decarburization-annealed steel strip as an intermediate material for grain-oriented electrical steel strip having good secondary recrystallization and excellent electrical properties is provided by causing a steel strip to possess a micro-structure in which the primary recrystallization grains have an average diameter d of not less than 15 .mu.m and a coefficient of diameter deviation .sigma.* of not more than 0.6.

Abstract: The present invention provides a thin sheet product having a combination of excellent magnetic properties inherent in the steel having a silicon content of 6.5% or near 6.5% with a further lowered iron loss property, particularly in a high frequency region, through the production of a magnetic thin steel sheet having a thickness of 0.23 mm or less by cold-rolling a steel sheet comprising by weight not more than that 0.006% of carbon, 5.0 to 7.1% of silicon, 0.07 to 0.30% of manganese, not more than 0.007% of sulfur, 0.006 to 0.038% of acid soluble aluminum and 8 to 30 ppm of total nitrogen with the balance consisting of iron and unavoidable impurities at a sheet temperature in the range of from 120.degree. to 350.degree. C. optionally after annealing the sheet at a temperature in the range of from 750.degree. to 1020.degree. C., and annealing the cold-rolled sheet at a temperature in the range of from 800.degree. to 1020.degree. C.

Abstract: In the present invention, grain oriented electrical steel sheets provided by heating a slab comprising, by weight percent, 0.025 to 0.075% of C, 3.4 to 5.0% of Si, 0.015 to 0.080% of sol. Al, 0.0030 to 0.013% of N, 0.014% or less of (S+0.405 Se) and 0.05 to 0.8% of Mn, sol. Al (%)/Si (%) being 0.0080 or more, the balance consisting of Fe and unavoidable impurities at a temperature below 1280.degree. C., hot-rolling the heated slab, subjecting the hot-rolled steel sheet to cold rolling, subjecting the cold-rolled steel sheet to decarbonization annealing with regulating the average diameter of primary recrystallized grains of the steel sheet subjected to decarbonization annealing to 18 to 35 .mu.

Abstract: Disclosed is a method for producing a grain-oriented electrical steel sheet having mirror surface containing 0.8 to 4.8% of Si in the form of a strip which has been subjected to a conventional series of operations including hot rolling with or without annealing, cold rolling once or at least twice with intermediate annealing to obtain a final thickness, decarburization annealing with or without nitriding treatment, coating the steel sheet with an annealing separator mainly containing non-hydrating oxide and final annealing, the improvement comprising:satisfying the relationshipA!>0.2.times. O!where A! is the total concentration of alkali metal impurity in the annealing separator (weight %), andO! is the amount of oxygen contained in the steel sheet just prior to the final annealing (g/m.sup.2).

Abstract: A process for producing a grain-oriented electrical steel sheet having a low watt loss, in which a steel strip consisting, in wt %, of 0.8 to 4.8 Si, 0.012 to 0.050 acid-soluble Al, 0.01 or less N, and the balance consisting of Fe and unavoidable impurities is cold-rolled to a final thickness of 0.15 mm or less, primary-recrystallization annealed, applied with a annealing separator containing magnesia as a major component by electrostatic spray painting, and then final-texture annealed.

Abstract: A very thin electrical steel strip having a thickness not exceeding 150 microns, an average grain diameter not exceeding 1.0 mm, a high degree of {110} <001> grain orientation, a high normalized magnetic flux density as expressed by a B.sub.8 /B.sub.s value which is greater than 0.9, and a low core loss not exceeding 50% of the core loss of any conventional product.It is produced from a starting material consisting of a grain-oriented electrical steel strip containing not more than 8% silicon, the balance thereof substantially being iron, and having a high degree of {110} <001> grain orientation, a normalized magnetic flux density as expressed by a B.sub.8 /B.sub.s value which is greater than 0.9, an average grain diameter of at least 20 mm in the rolling direction and an average grain diameter of at least 40 mm in the direction perpendicular to the rolling direction.

Abstract: The present invention is a process for manufacturing a double oriented electrical steel sheet having a high magnetic flux density by carrying out a low temperature annealing for the secondary recrystallization by the use of AlN as inhibitor, characterized by hot-rolling a silicon steel slab comprising 1.8-4.8% by weight of Si, 0.008-0.048% by weight of acid soluble Al, 0.0028-0.0100% by weight of acid soluble Al, 0.0028-0.0100% by weight of total N, not more than 0.016% by weight of S and the balance being Fe and unavoidable impurities into a hot-rolled sheet, subjecting the sheet to cold-rolling at a reduction rate of 40-80%, subsequently subjecting the sheet to another cold-rolling at a reduction rate of 30-70% in the direction crossing the cold-rolled direction, annealing at 750.degree.-950.degree. C. in a wet hydrogen atmosphere for decarburization, and carrying out the final finishing annealing which comprises a stage for completing the secondary recrystallizing at a temperature of 920.degree.-1100.

Abstract: The present invention provides a process for manufacturing a double oriented electrical steel sheet having a high flux density by suppressing the growth of the secondary recrystallization of {110} <uvw> oriented grains from the surface of the steel sheet in the hot-rolling stage or cold-rolling stage, which process comprises subjecting a hot rolled sheet comprised of 0.8-6.7% by weight of Si, 0.008-0.048% by weight of acid soluble Al, 0.

Abstract: An ultrahigh silicon, grain-oriented electrical steel sheet having a magnetic flux density, B.sub.8, of 1.57 or more and a degree of azimuth orientation, R (B.sub.8 /B.sub.s) of 0.87 or more is provided by cold-rolling an ultrahigh silicon steel sheet comprising by weight 0.005 to 0.023% of C, 5 to 7.1% of Si, 0.014% or less of S, 0.013 to 0.055% of acid soluble Al and 0.0095% or less of total N with the balance consisting of Fe and unavoidable impurities at a temperature in the range of from 120.degree. to 380.degree. C. optionally after annealing at a temperature in the range of from 800.degree. to 1100.degree. C.

Abstract: A process for producing a grain-oriented electrical steel sheet having a high magnetic flux density, comprising the steps of: heating a steel slab comprising 1.8 to 4.8 wt % Si, 0.012 to 0.050 wt % acid-soluble A1, 0.010 wt % or less N, and the balance consisting of Fe and unavoidable impurities, to a temperature for hot rolling; hot-rolling the heated slab to form a hot-rolled strip; cold-rolling the hot-rolled strip to a final product sheet thickness at a final cold rolling reduction of 80% or more by a single step of cold rolling or by two or more steps of cold rolling with an intermediate annealing step inserted therebetween; primary-recrystallization-annealing the cold-rolled strip; final-annealing the primary-recrystallization-annealed strip so that secondary-recrystallized grains substantially completely grow up in a temperature region of from 1000.degree. to 1100.degree. C. and then purification is effected above 1100.degree. C.

Abstract: A process for producing a grain-oriented electrical steel sheet having an excellent magnetic characteristic, comprising the steps of: heating to a temperature lower than 1280.degree. C. a steel slab comprising 0.025 to 0.075 wt % C, 2.5 to 4.5 wt % Si, 0.010 to 0.060 wt % acid-soluble Al, 0.0030 to 0.0130 wt % N, 0.014 wt % or less (S+0.405 Se), 0.05 to 0.

Abstract: A method of producing grain oriented silicon steel sheets each having a low watt loss, at an inexpensive cost and a high operational efficiency, wherein surfaces of each silicon steel sheet are given a mirror surface is disclosed. After completion of a finish annealing, forsterite films on the surface of each grain oriented silicon steel sheet are removed therefrom, and thereafter, the silicon steel sheet is annealed within the temperature range of 1000.degree. C. or higher in an atmosphere composed of a mixture gas comprising 20 to 80% by volume of hydrogen gas and 0 to 80% by volume of an inert gas, whereby surfaces of the silicon steel sheet are given a mirror surface. Subsequently, tensile stress additive films are formed on the surfaces of the silicon steel sheet, and consequently, the resultant silicon steel sheet exhibits a remarkably reduced watt loss.

Abstract: A method of producing an oriented electrical steel sheet having superior magnetic properties comprises the steps of, hot rolling a slab containing 0.8 to 6.8% of Si, 0.008% of Al acid soluble, the balance being Fe and accompanying impurities, by weight to form a strip, cold rolling the strip, primary-recrystallization annealing, coating the strip with an annealing separator, and finishing annealing, a nitriding treatment being effected after the primary recrystallization annealing but before the start of the secondary recrystallization of the finishing annealing. According to the present invention, with an atmosphere oxidizing degree (PH.sub.2 O/PH.sub.2): x in a soaking process in said primary recrystallization annealing an annealing is effected in an atmosphere which has an oxidizing degree (PH.sub.2 O/PH.sub.2): y in a range defined by the following inequality, at a temperature ranging from 650.degree. to 800.degree. C. in the heating process, for at least 5 secs.

Abstract: The present invention provides a wound core having a low core loss and not susceptible to a disappearance of the core loss lowering effect due to a magnetic domain refining even when stress-relief annealing is conducted after fabrication of a steel strip into a wound core, through a process which comprises, fabricating a very thin silicon steel strip comprising by 6.5% weight or less of silicon with the balance consisting essentially of iron and having a sheet thickness of 100 .mu.m or less and a magnetic flux density (B.sub.8 value) of 1.80T or more into a wound core, subjecting the wound core to stress-relief annealing, unwinding the very thin silicon steel strip from the core, introducing into the very thin silicon steel strip a linear or dotted local strain in a direction at an angle of 45.degree. to 90.degree. to the rolling direction of the thin strip, and rewinding the thin strip onto the core.

Abstract: In the conventional process for the production of a double-oriented electrical steel sheet, the preparation steps are complicated and the manufacturing cost is very high. Nevertheless, the magnetization characteristic B.sub.10 is lower than 1.85 Tesla and the final sheet thickness cannot be reduced below 0.30 mm. According to the present invention, by strictly controlling the secondary recrystallization temperature and performing a third cold rolling in the same direction as the rolling direction of the first cold rolling, the magnetization characteristic B.sub.10 can be increased above 1.88 Tesla and the final sheet thickness can be reduced to 0.20 mm. Moreover, a double-oriented electrical steel sheet having an excellent shape (flatness) and a much smaller thickness deviation in the longitudinal direction of the product can be produced on an industrial scale. Therefore, this product can be effectively used as a core material of a large-size rotary machine or in a small-size static magneto-electronic device.