| abstract |
PURPOSE: To impress a minute plastic strain in order to remarkably reduce the iron loss, by irradiating the laser rays on the surface of the steel sheet shose structure is previously regulated to the (100) [001] structure through the recrystallization annealing treatment. n CONSTITUTION: The laser beam is irradiated perpendicularly upon the surface of the electrical steel sheet 1 in the direction inclined by an angle 90W30 degrees against the direction of the rolling work, through the slit 3 arranged between the already finish annealed directional electrical steel sheet 1 and the pulse laser 2. Hereupon, the breadth of irradiation is taken as (d), the energy density as P, and the interval of irradiations as l; then, the irradiation is controlled so as to satisfy the following relation, 0.005≤d/l×P 2 ≤1.0. The surface of the steel sheet to be irradiated by the laser beam, can be the surface as it is rolled, the surface mirror polished, or the surface applied with the insulating film beforehand. According to this method, a minute plastic strain can be impressed without causing any change in the steel sheet surface, and the iron loss of the electrical steel sheet is remarkably reduced. n COPYRIGHT: (C)1980,JPO&Japio |