Abstract: An electrical steel sheet having a very small watt loss can be provided by improving the conventional magnetic domain-controlling treatment. Namely, a high-flux density, grain-oriented electrical steel sheet having a superior watt loss characteristic and a flux density of at least 1.88 T at a magnetizing force of 800 A/m, which comprises, as the steel sheet components, up to 0.0030% by weight of C, 2.8 to 4.5% by weight of Si, 0.045 to 0.100% by weight of Mn, up to 0.0050% by weight of one or two elements selected from the group consisting of S and Se, up to 0.0050% by weight of Al, up to 0.0030% by weight of N, 0.03 to 0.25% by weight of Sn, 0.35 to 2.0% by weight of Ni and if necessary, 0.03 to 0.

Abstract: Disclosed is a process for preparing a thin grain oriented electrical steel sheet having a final thickness of 0.05 to 0.25 mm from a silicon steel cast strip having a thickness of 0.2 to 5 mm and directly obtained from the molten steel by the synchronous continuous casting machine, in which the speed of movement of the strand relative to the inner wall surface of the casting mold is the same, and by which the traditional hot rolling process can be omitted, comprising 0.050 to 0.120% by weight of C, 2.8 to 4.0% by weight of Si and 0.05 to 0.25% by weight of Sn, wherein the starting silicon cast strip further comprises up to 0.035% by weight of S and 0.005 to 0.035% by weight of Se, with the proviso that the total amount of S and Se is in the range of 0.015 to 0.060% by weight, 0.050 to 0.090% by weight of Mn, with the proviso that the Mn content is in the range of {1.5.times.[content (% by weight) of S+content (% by weight) of Se]} to {4.5.times.

Abstract: The present invention provides a grain-oriented electrical steel sheet having a thickness of up to 0.17 mm and excellent product magnetic characteristics. The present invention is characterized in that a silicon containing acid-soluble Al, N and Sn is used as the starting material, the N and acid-soluble Al contents in the slab are adjusted to 0.0050 to 0.0100% and {(27/14).times.N (%)+0.0035} to {(27/14).times.N (%)+0.0100}%, respectively, the thickness of the hot-rolled sheet is adjusted so that the thickness reduction ratio at the one-stage cold-rolling is 85 to 92%, and the Nas AlN content in the hot-rolled steel sheet is controlled to 0.0005 to 0.0020%.

Abstract: Disclosed is a process for preparing a thin grain oriented electrical steel sheet having a final thickness of 0.05 to 0.25 mm from a silicon steel slab comprising 0.050 to 0.120% by weight of C, 2.8 to 4.0% by weight of Si and 0.05 to 0.25% by weight of Sn, wherein the starting silicon slab further comprises up to 0.035% by weight of S and 0.005 to 0.035% by weight of Se, with the proviso that the total amount of S and Se is in the range of 0.015 to 0.060% by weight, 0.050 to 0.090% by weight of Mn, with the proviso that the Mn content is in the range of {1.5.times.[content (% by weight) of S+content (% by weight) of Se[} to {4.5.times.[content (% by weight) of S+content (% by weight) of Se[} % by weight, 0.0050 to 0.0100% by weight of N, and {[27/14].times.content (% by weight) of N+0.0030} to {[27/14].times.content (% by weight) of N+0.0150} % by weight of acid-soluble Al.

Abstract: In a grain-oriented electromagnetic steel sheet which is produced by a process including a cold-rolling step(s), the final reduction ratio of the cold-rolling step(s) being high, a technical means for refining the secondary recrystallized grains is particularly important. One technical means is the incorporation of tin into silicon steel material. This, however, involves a problem because tin incorporated into silicon steel material deteriorates the surface coating which imparts tension to a grain-oriented electromagnetic steel sheet.The incorporation of copper into silicon steel material has been avoided since it causes secondary recrystallization to be unstable.The present invention is characterized by the combined incorporation of tin and copper into molten steel so as to simultaneously refine the secondary recrystallized grains and to form a good surface coating. The grain-oriented electromagnetic steel sheet of the present invention contains from 2.5% to less than 4.0% of silicon, from 0.03% to 0.

Abstract: The present invention relates to an improvement in the precipitation annealing of a hot-rolled steel sheet or strip which is carried out immediately before cold-rolling in the production of a grain-oriented electromagnetic steel sheet or strip. Conventionally, precipitation annealing is carried out by heating a steel strip to a temperature of from 750.degree. to 1200.degree. C. and then quenching it. The present invention proposes to control the cooling rate during primary cooling, i.e. from a holding temperature (T.sub.1 temperature) of from 1080.degree. to 1200.degree. C. down to an intermediate temperature (T.sub.2 temperature) of from 900.degree. to 980.degree. C., and to control the staying time during primary cooling so that excellent magnetic properties can be obtained regardless of the unavoidable variation in the Al and Si content. The present invention also proposes to control the rate of temperature elevation between 800.degree. C.

Abstract: In a grain-oriented electromagnetic steel sheet which is produced by a process including a cold-rolling step(s), the final reduction ratio of the cold-rolling step(s) being high, a technical means for refining the secondary recrystallized grains is particularly important. One technical means is the incorporation of tin into silicon steel material. This, however, involves a problem because tin incorporated into silicon steel material deteriorates the surface coating which imparts tension to a grain-oriented electromagnetic steel sheet.The incorporation of copper into silicon steel material has been avoided since it causes secondary recrystallization to be unstable.The present invention is characterized by the combined incorporation of tin and copper into molten steel so as to simultaneously refine the secondary recrystallized grains and to form a good surface coating. The grain-oriented electromagnetic steel sheet of the present invention contains from 2.5% to less than 4.0% of silicon, from 0.03% to 0.

Abstract: The present invention provides an annealing separator comprising from 0.05 to 2.0 parts by weight of antimony sulfate based on 100 parts by weight of magnesium oxide, and at least one chloride selected from the group consisting of Sb, Sr, Ti, and Zr chlorides in a chlorine amount of from 5 to 20% by weight based on 100% of the chloride and antimony sulfate, and occasionally comprises Ti oxide in an amount of from 0.5 to 10 parts.The annealing separator is applied on the decarburization annealed strip, and improves both the magnetic properties and properties of glass film, in the production of a grain-oriented electrical steel sheet.

Abstract: In a process for producing a grain-oriented silicon steel strip, comprising the steps of: hot rolling, annealing, if necessary; heavy cold rolling; decarburization-annealing, and; final annealing, an improvement which comprises controlling a coiling temperature after the finish rolling of the hot rolling step within a range of from 700.degree. to 1000.degree. C. As a result of the coiling temperature control, the annealing of the hot rolled strip can be simplified or omitted, while the behavior of a grain-growth inhibitor is equivalent to that in the conventional process including the annealing step. The magnetic flux density of the material produced by the process of the present invention is excellent, notwithstanding the simplification or omission of the annealing.

Abstract: A grain oriented electrical silicon steel sheet containing aluminium and having an extremely high magnetic flux density, for example, a B8 of 1.90 or more, is produced by a secondary recrystallization annealing operation in which, during the period of elevating the temperature of a reducing atmosphere to a level within a range of from 850.degree. to 950.degree. C., the partial pressure of nitrogen in the reducing atmosphere is limited to 20% or less based on the entire pressure of the reducing atmosphere, and during the period of elevating the temperature of the reducing atmosphere in which the secondary recrystallization is in progress, the partial pressure of nitrogen is maintained at a level of at least 3%.

Abstract: Annealing separator for heat treatment of a silicon steel sheet comprising not more than 0.2% SO.sub.3, not more than 0.04% Cl with the balance being MgO and unavoidable impurities, and having a bulk density between 0.18 and 0.30 g/cm.sup.3, and a particle size distribution of 40 to 70% of particles not larger than 3.mu.m, 10 to 25% of particles not smaller than 10.mu.m, not more than 15% of coarse particles larger than 15.mu.m with the balance being intermediate particles between 3.mu.m and 10.mu.m.