Grain-Oriented Electrical Sheet Superior in Watt Loss

Abstract

The present invention provides grain-oriented electrical sheet more superior in watt loss compared with the past by dividing the watt loss of grain-oriented electrical sheet introducing strain by firing of a laser beam etc. into hysteresis loss and eddy current loss and, in particular from the viewpoint of the eddy current loss, quantitatively suitably controlling the distribution of the strain and residual stress in the sheet thickness direction, that is, grain-oriented electrical sheet obtained by firing a laser beam etc. to introduce lines of strain substantially perpendicular to the rolling direction uniformly in a sheet width direction and cyclically in the rolling direction for magnetic domain control, characterized in that in the two-dimensional distribution of a rolling direction compressive residual stress occurring near one location of the introduction of strain in a cross-section perpendicular to the sheet width direction, the value of the rolling direction compressive residual stress integrated in the region of the cross-section where there is compressive residual stress is within a predetermined range.

1 . A grain-oriented electrical sheet obtained by firing a continuous wave laser beam to introduce strain uniformly in a sheet width direction perpendicular to a rolling direction, cyclically in the rolling direction, and in lines substantially perpendicular to the rolling direction, characterized in that in the two-dimensional distribution of a rolling direction compressive residual stress occurring near one location of the introduction of strain in a cross-section perpendicular to the sheet width direction, the value of the rolling direction compressive residual stress integrated in the region of the cross-section where there is compressive residual stress is 0.20 N to 0.80 N. 
   
   
       2 . A grain-oriented electrical sheet as set forth in  claim 1 , characterized in that a cyclic pitch in said rolling direction of the strain uniform in said sheet width direction due to firing of the laser beam is 2 mm to 8 mm.