Method for treating an electromagnetic steel sheet and an electromagnetic steel sheet having marks of laser-beam irradiation on its surface
AssigneeNippon Steel Corporation
InventorsTadashi Ichiyama, Shigehiro Yamaguchi, Tohru Iuchi, Motoharu Nakamura, Yozo Suga
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Abstract
A process of providing electromagnetic steel strips or sheet with excellent magnetic properties. The process comprises the steps of: irradiating with a laser-beam the surface of an electromagnetic steel sheet which has been finally annealed, thereby locally forming marks of the laser-beam irradiation on the surface of the steel, and; subsequently, subjecting the steel sheet to the formation of an insulating film on the sheet surface at a temperature of the sheet not exceeding 600.degree. C.
Claims8
A method for treating an electromagnetic steel sheet to reduce its watt loss after completion of its final heat treatment, and comprising irradiating at least one surface of the finally heat-treated sheet with a laser beam having an energy density of from 0.01 to 1000 J/cm.sup.2 so as to mark the sheet's surface and cause a substantial reduction in the sheet's watt loss, and thereafter a liquid insulating film-forming agent requiring treating at temperatures not higher than 600.degree. C. is coated on the surface and the coated sheet is treated at temperatures not higher than 600.degree. C. so as to form an insulating film on the surface.
Dependencies are inferred from the claim text.