| 摘要 |
<p>PURPOSE:To press locally an insulating film into a base metal and to reduce the iron loss of a silicon steel sheet by irradiating a finish-annealed grain oriented silicon steel sheet having an insulating film with at least two electron beams dissimilar in acceleration energy along the width direction of this steel sheet. CONSTITUTION:After finish annealing is applied to a grain oriented silicon steel sheet, e.g., a forsterite film h2 is formed on the above steel sheet and also an insulating film h1 is further formed on the above. Subsequently, the resulting coated steel sheet is irradiated with an electron beam A which has high voltage and small electric current and also has relatively narrow beam diameter and penetrates deeply into the steel sheet, by which local and recessed minute melted regions are formed in the interface between the film and the base metal and simultaneously the film is pressed into these regions to fractionize a magnetic domain. Then, the above sheet is irradiated with an electron beam B of low voltage and small electric current, by which strain in the forsterite film or the insulating film can be released and deterioration in magnetic properties due to the presence of strain can be avoided, and further, iron loss can be advantageously reduced.</p> |
