Abstract: A grain-oriented electrical steel sheet excellent in film and iron loss characteristics. The steel sheet contains up to 0.005% of C, 2.0 to 7.0& Si in terms of weight % and the balance iron and unavoidable impurities. An oxide film which mainly contains forsterite is formed on the surface and an insulating coating is formed on the oxide film. The peak intensity of Si obtained by glow discharge spectral analysis (GDS analysis) from the oxide film surface is at least ½ of that of Al, and the depth of the peak position of Si from the oxide film surface us up to {fraction (1/10)} of the depth of that of Al. The sheet satisfies the formulas for a ratio y(%) with which peeling of the oxide film does not take place when subjected to a bending test with a curvature of 20 mm and for core loss characteristic W (W/kg): y(%)≧−122.45t+112.55 W (W/kg)≦2.37t+0.280 wherein t represents a sheet thickness in terms of mm.

Abstract: The present invention provides a grain-oriented electrical steel sheet excellent in film characteristics and iron loss characteristics, a process for producing the same and a decarburization annealing facility used for the process.

Abstract: A process for producing a grain-oriented electrical steel sheet wherein during the decarburization annealing step, the steel sheet is first rapidly heated in a rapid heating chamber and the PH2O/PH2 ratio in the rapid heating chamber is more than the PH2O/PH2 ratio in the decarburization annealing furnace so as to provide improved oxide film adhesion.

Abstract: A continuously cast slab of grain-oriented electrical steel is heated, subjected to heavy-reduction edge rolling at such amount not less than 60 mm as is required for matching with the width of a hot-rolled coil to be produced therefrom, whereafter the dogbones formed in the slab by the heavy-reduction edge rolling are eliminated by horizontal rolling to obtain a flat slab. The flat slab is then heated to a high temperature and hot rolled. Optionally, the edges of the slab can be heated prior to the finish rolling step of the hot rolling process. The method enables production of grain-oriented electrical sheet with high productivity.

Abstract: The present invention relates to a process for producing a grain-oriented electrical steel sheet by means of the so-called double-rolling process, using Mn, S, and Cu as the precipitation dispersion phases for suppressing the growth of primary-recrystallized crystal grains.A new concept according to the present invention is to suppress the growth of primary crystals by means of an element segregated in the grain boundaries of primary-recrystallized crystals.The present invention is characterized in that the silicon steel starting material contains T.[N] in an amount which satisfies the following formulas (1) and (2):T.[N].gtoreq.{[sol Al%].times.(14/27)+0.0020}(%) (1)T.[N].ltoreq.{[sol Al%].times.(14/27)+0.0060}(%) (2).

Abstract: A method for treating a continuously cast steel slab suitable for production of a hot rolled or cold rolled steel sheet, the steel slab being obtained by continuously casting a molten steel containing 0.01 to 2.5% by weight of Al, which method comprises holding the slab at a temperature within the range of from the Ar.sub.3 point to 650.degree. C for at least 20 minutes to precipitate nitrides, and hot rolling the slab.