| 摘要 |
PURPOSE:To produce a grain-oriented silicon steel sheet having high magnetic flux density by soaking a steel sheet before final cold rolling at a specific temp. for a specific length of time, holding the above sheet at a specific soaking temp. for a specific length of time, carrying out heat treatment in which cooling is performed at a specific velocity, and carrying out nitriding treatment in the course between decarburizing annealing and the initiation of secondary recrystallization in final finish annealing. CONSTITUTION:A slab of a silicon steel having a composition containing, by weight 0.025-0.075% C, 2.5-4.5% Si, 0.01-0.06% acid-soluble Al, etc., is heated up to <=1200 deg.C and hot-rolled. The final rolling reduction is regulated to >=80% by means of one or more rollings. Subsequently, decarburizing annealing and finish annealing are performed. At this time, the steel sheet before final cold rolling is soaked at 900-1080 deg.C for <=180sec and held at 750-900 deg.C for 30-300sec, and further, nitriding treatment is carried out in the course between decarburizing annealing and the initiation of secondary recrystallization in the final finish annealing. By this method, the grain-oriented silicon steel sheet excellent in magnetic properties can be produced. |
