UNIDIRECTIONAL ELECTROMAGNETIC STEEL SHEET HAVING EXCELLENT FILM CHARACTERISTICS AND MAGNETIC CHARACTERISTICS, ITS PRODUCTION METHOD AND DECARBURIZATION ANNEALING SETUP THEREFOR

摘要

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. The grain-oriented electrical steel sheet comprises up to 0.005% of C, 2.0 to 7.0% of Si in terms of weight % and the balance Fe and unavoidable impurities, has an oxide film which mainly contains forsterite and is formed on the surface, and an insulating coating formed on the oxide film, wherein the amount of the oxide film is from 1 to 4 g/m<2> per side, the peak intensity of Si obtained by glow discharge spectral analysis (GDS analysis) from the oxide film surface is at least 1/2 of that of Al, and the depth of the peak position of Si from the oxide film surface is up to 1/10 of the depth of that of Al, and shows 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 core loss characteristics W (W/kg) satisfying the following formulas, respectively: $wherein\; t\; represents\; a\; sheet\; thickness\; in\; terms\; of\; mm,$ wherein\; t\; represents\; a\; sheet\; thickness\; in\; terms\; of\; mm.\mathop{\mathrm{image}}$$