Patent ID: 6444050
Filing Date: 2002-09-03
Classification: C21D,C22C,H01F

Abstract:
In a method for producing a grain-oriented electromagnetic steel sheet having a low iron loss and excellent strain resistance and capable of excellent performance in a practical device, the steps comprising:hot-rolling a silicon steel slab containing about 0.010 to 0.120 wt % of C, about 1.5 to 7.0 wt % of Si and about 0.03 to 2.5 wt % of Mn and having a composition containing one or more of inhibitor components; forming said sheet final thickness by cold-rolling at least once, or twice or more with intermediate annealing; subjecting said sheet to a primary recrystallization annealing to create primary recrystallization grains, followed by secondary recrystallization annealing; and artificially and sparsely providing a plurality of specially treated areas in said steel sheet with a projection area corresponding to a diameter of a circle of about 0.05 mm to 3.0 mm on the surface of said steel sheet during the time between midway in the primary recrystallization annealing step and the start of the secondary recrystallization, wherein said specially treated areas result in one or more of the following during said secondary recrystallization annealing: (1) enhancing a driving force for abnormal grain growth, abnormal grain growth being rapid growth of quite minor grains having random orientation by invading into other overwhelmingly major crystal grains; (2) extinguishing an inhibition force of said inhibitor components; or (3) suppressing growth of secondary recrystallization grains.