GRAIN ORIENTED SILICON STEEL SHEET EXCELLENT IN FILM CHARACTERISTIC AND PRODUCING METHOD THEREFOR

摘要

PROBLEM TO BE SOLVED: To produce a grain oriented silicon steel sheet with a high occupying volume ratio having a tension applying effect higher than that by the conventional method, excellent in adhesion and magnetic properties and moreover excellent in corrosion resistance which allows the same to withstand the practical use and to provide a method for producing an insulating film therefor. SOLUTION: This grain oriented silicon steel sheet has an insulating film composed of a layer essentially consisting of the hydrogen phosphate of a bivalent or trivalent metal and silica as a first layer and a layer essentially consisting of aluminum borate whose surface roughness is controlled to 0.1 to 0.50 μm by Ra (center line average roughness) as a second layer on the surface.