| 摘要 |
PURPOSE:To obtain the directional silicon steel plate having no characteristic deterioration caused by strain-removing annealing by a method wherein a forsterite film is locally removed, a metal having the coefficient of thermal expansion different from that of base iron is adhered to the surface where the forsterite film is removed, and an insulative coating which gives tension is performed. CONSTITUTION:After an annealing isolation agent, having MgO as the main component, is applied on the surface of a steel plate, an annealing for secondary recrystallization is performed, subsequently a high-temperature purification annealing is performed, and forsterite is formed on the surface where the annealing isolation agent is applied. A forsterite-removing process is performed after the last finishing annealing or insulating coating is performed. Forsterite can be partially removed by performing an etching with an HF solution using a suitable mask, or by performing a scraping off method using a knife edge and so on. Iron loss characteristics can be improved by removing the forsterite film, and a heterogenous metal region is formed in a divided manner on the surface layer of the base iron located directly below the part where the forsterite film is removed. |
