PRODUCTION OF GRAIN-ORIENTED SILICON STEEL SHEET FREE FROM SURFACE BLISTER DEFECT

摘要

PURPOSE:To produce a product free from deterioration in magnetic flux density at a low cost by directly applying, without hot rolled plate annealing, cold rolling to a silicon steel plate and specifying the diameter of rolls for cold rolling at this time. CONSTITUTION:A slab of a silicon steel having a composition containing, by weight, 1.5-6.7% Si, 0.012-0.04% acid-soluble Al, and =0.0095% N is hot-rolled and is formed into the final sheet thickness by means of a single cold rolling. Subsequently, the resulting sheet is subjected to decarburizing annealing in wet hydrogen and to finish high-temp. annealing for secondary recrystallization and purification. At this time, nitriding treatment is carried out in the course between decarburizing annealing and the initiation of secondary recrystallization. Further, at the time of the above cold rolling, cold rolling is directly applied to the above plate without hot rolled plate annealing, and the diameter of rolls for cold rolling at this time is regulated to =150mm. By this method, the product of silicon steel sheet free from surface blister defect can be produced.