METHOD FOR APPLYING STRESS RELIEF ANNEALING TO GRAIN-ORIENTED SILICON STEEL SHEET FREE FROM SEIZURE OF STEEL SHEET AT THE TIME OF STRESS RELIEF ANNEALING AND EXCELLENT IN MAGNETIC PROPERTY

摘要

PURPOSE:To prevent seizure from occurring to a steel sheet, by limiting moisture content in an annealing-atmosphere gas to a specific value or below at the time of subjecting a wound core formed from a grain-oriented silicon steel sheet to stress relief annealing. CONSTITUTION:The wound core is worked by using a grain-oriented silicon steel sheet product which is held in a continuous or batch furnace at about 800-850 deg.C for about 2-4hr to undergo stress relief annealing. At this time, N2 or a gas prepared by mixing several percent of H2 gas into N2 is used as an atmospheric gas, and moisture content in the above gas is limited to =5mg/m3. In this way, the wound core free from seizure of steel sheet and having excellent magnetic properties can be obtained.