A grain oriented electromagnetic steel sheet has a plurality of linear fine strains having a traverse section of a concave hollow on it in the steel sheet shows a very low iron loss in its use.

Grain-oriented electromagnetic steel sheet

A process is taught for improving the core loss of magnetic materials of the type having a plurality of magnetic domains and an insulative coating thereon. The insulative coating may be a mill glass, an applied coating, or both. The magnetic material is scanned by the beam of a laser across its rolling direction so as to subdivide the magnetic domains without damage to the insulative coating.

Laser treatment of electrical steel

A machine manipulates a laser beam substantially transversely across a moving sheet of flat or curved material. This machine includes a rotating optical system which focuses and moves an elongate beam spot across the moving sheet of flat or curved material, at a high rate of speed. In methods of applying these instruments to produce reductions in watt loss in coated ferromagnetic sheet without damage to the coating, the speed of laser scanning, S 2 (inches/minutes), and the incident power, P (watts), of the beam are selected such that the function, PS 2 -1/2 is between about 0.1 to about 7.

Laser scribing apparatus and process for using

In a method of producing a grain-oriented electromagnetic steel sheet, a laser beam is irradiated onto the steel sheet, which has been subjected to a final high temperature annealing in order to approximate the crystal orientation of the sheet in a (110), [001] orientation. Because of the laser beam irradiation, regions of high dislocation density are locally formed in the steel sheet and subdivide the magnetic domains, with the result that a low watt loss is achieved.

Grain-oriented electromagnetic steel sheet with improved watt loss

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° C.

Method for treating an electromagnetic steel sheet and an electromagnetic steel sheet having marks of laser-beam irradiation on its surface

A method of producing a grain-oriented electromagnetic steel sheet comprising the step of subjecting a sheet of hot-rolled steel containing silicon less than 4.5% to more than one operation of cold rolling and more than one operation of annealing, so as to set the thickness of said sheet to that of a commercially standard sheet, and also subjecting the sheet to the step of final high-temperature annealing. Prior to said final high-temperature annealing, part of the surface of said sheet is worked for controlling the growth of secondary recrystallization grains by working the sheets such that lines of less than 3.0 mm wide are formed on the surface of the steel sheet spaced apart at intervals of more than 5.0 mm so that the total effect is to produce worked and unworked regions alternatively arranged in lines across the steel sheet. Such working is effected by mechanical plastic working, local thermal treatment and by chemical treatment. The worked regions serve to control the growth of secondary recrystallization.

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Papers

Method of producing grain oriented electromagnetic steel sheet

Verfahren zur herstellung kornorientierter elektrobleche