High flux density one side stable manufacturing method null of satisfactory primary insulating membrane of tropistic electromagnetic

摘要

PURPOSE:To stably form a superior primary insulation coating on a grain-oriented silicon steel plate having high magnetic flux density by removing a surface oxide film from a sheet of a silicon steel with a specific composition, exerting annealing under specific conditions, and then carrying out direct cold rolling. CONSTITUTION:At the time of using a plate of a silicon steel having a composition consisting of, by weight, 0.8-4.8% Si, =0.014% S, 0.008-0.048% acid-soluble Al, =0.0095% total N, and the balance Fe with inevitable impurities as a starting material, exerting short-time annealing at 800 -1120 deg.C, performing cold rolling and decarburizing annealing, applying a separation agent at annealing composed essentially of MgO to the resulting cold rolled sheet, and then carrying out high temp. finish annealing, nitriding treatment is applied to the sheet in the course between decarburizing annealing and high temp. finish annealing to produce a grain- oriented silicon steel sheet. In this manufacturing process, a surface oxide film is removed from the silicon steel plate as a starting material, and then, this material is annealed in an atmosphere having an oxygen potential where the surface C content of the material after annealing does not decrease practically, followed by direct cold rolling. By this method, the grain-oriented silicon steel sheet having high magnetic flux density and superior primary insulation coating can be stably obtained.