抄録
The residual stress distributions near the laser-irradiated line in a crystal grain of the grain-oriented silicon steel sheet were studied by the X-ray stress measurement method for a single crystal, in order to clarify the mechanism of the magnetic domain refinement. The distributions of residual stresses were measured before and after the stress-relief annealing. The change in magnetic domain structures was also observed in this process. After the laser irradiation, the refinement of magnetic domain was observed. In addition, the inhomogeneous deformations such as plastic strains were induced near the laser-irradiated line, and the tensile residual stresses of 50-200 MPa were generated. Moreover, the slight compressive residual stresses were recognized in approximately 0.15 mm depth from the laser-irradiated surface. However, these compressive stresses did not affect the magnetic domain refinement. After stress-relief annealing, the residual stresses were relieved, and the magnetic domain then returned to its original width. Therefore, it was supposed that the change in magnetic anisotropy induced by the local plastic strain generates the 90-degree magnetic domains near the laser irradiation and that the local tensile stresses near the laser-irradiated line destabilize theses 90-degree magnetic domains so as to refine the 180-degree domains.
