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

摘要

A unidirectional electromagnetic steel sheet having excellent film characteristics and iron loss characteristics, containing up to 0.005 wt.% of C, 2.0 to 7.0 wt.% of Si and the balance of Fe and unavoidable impurities, and having an oxide film consisting principally of forsterite and an insulating film formed on the oxide film, wherein the film quantity of the oxide film per surface is 1 to 4 g/m<2>, the peak strength of Si obtained by glow discharge emission analysis is at least 1/2 of that of Al, the depth from the surface of the oxide film to the Si peak position is within 1/10 of the depth of the Al peak position from the surface of the oxide film, and the non-occurrence ratio y (%) of the peel of the film by 20 mm-radius bending and the iron loss characteristics W (W/kg) satisfy the following formulas: y (%) >/= -122.45t + 112.55 (where t: sheet thickness mm), W (W/kg)