PURPOSE: To produce a grain-oriented silicon steel sheet having high magnetic flux density and reduced in iron loss by polishing the surface of a finish- annealed grain-oriented silicon steel sheet and then forming a high-tension TiN film and a TiAlN film by means of ion plating.
CONSTITUTION: A silicon steel slab is hot-rolled, and the resulting hot rolled plate is subjected to homogenizing annealing and further to cold rolling twice, while process-annealed between the cold rolling stages, so as to be formed into a cold rolled steel sheet of the final sheet thickness. Subsequently, decarburizing and primary recrystallization annealing is applied to the above steel sheet, and a separation agent at annealing is applied to the steel sheet to carry out secondary recrystallization annealing and purification annealing. After the removal of surface oxide film, the steel sheet surface is polished so as to be finished into mirror-like state. Successively, a high-tensile TiN film and a TiAlN film are formed by means of ion plating. By this method, the grain- oriented silicon steel sheet excellent in thermal stability, remarkably reduced in iron loss, and having superior electromagnetic characteristics can be produced.
KOBAYASHI YASUHIRO
SUZUKI KAZUHIRO
