Abstract: The present invention provides a grain-oriented electrical steel sheet having magnetic properties equal to, or higher than, those of conventional steel sheets can be produced economically with high productivity, and a method for producing such a steel sheet. The producing method comprises the steps of using, as a starting material, a coil obtained by heating a slab having a composition comprising, in terms of percent by weight, 0.02 to 0.15% of C, 2.5 to 4.0% of Si, 0.02 to 0.20% of Mn, 0.015 to 0.065% of Sol. Al, 0.0030 to 0.0150% of N, 0.005 to 0.040% as the sum of at least one of S and Se and the balance substantially consisting of Fe and hot rolling the slab to a coil, or a coil directly cast from a molten steel having the same components as the slab, conducting hot rolled sheet annealing at 900 to 1,100.degree. C.

Abstract: Very high magnetic flux density grain-oriented electrical steel slab containing 2.5 to 4.0 weight percent silicon as an essential component and having a very high magnetic flux density B.sub.8 of not less than 1.92 tesla, in which by area not less than 80 percent is accounted for by matrix secondary recrystallization grains having a diameter not larger than 100 mm and not smaller than 10 mm in a direction of cold rolling and not larger than 50 mm and not smaller than 5 mm in a direction perpendicular to the cold rolling direction, and in which, moreover, of the grains in said matrix, not fewer than 50 percent by ratio of number are fine secondary recrystallization grains having an average diameter not larger than 5 mm.

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 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.