Measurement of Residual Stress Induced by Laser Irradiation on Grain Oriented Silicon Steel Using X-Ray Diffraction
Kazuyuki SUEYOSHICKoichi AKITACShin-ichi OHYACHiroshi SUZUKICMuneyuki IMAFUKU and Keiji IWATA
Abstract:Grain-oriented 3%Si steel has been widely used for transformer cores. The reduction of iron loss is the most important factor for the development of the material and can be achieved by segmentation of magnetic domain of the material. The segmentation of magnetic domain is occurred by introduction of the residual stress induced by a laser pulse irradiation on the material. In this study, the residual stress distributions near laser pulse spots on a grain-oriented 3%Si steel were measured using an X-ray stress measurement method for single crystal and the generation mechanism of the residual stress was discussed. Laser pulses with 100ƒÊm in diameter were irradiated on the surface of the material. Tensile residual stress was generated near the center of laser spot and it rapidly decreased with increasing distance from the center of spot. The in-plane residual stresses showed anisotropy, however the in-plane strains calculated from the residual stresses and anisotropic elastic properties were isotopic. The X-ray diffraction profiles near the laser spots were broadened and it showed that the plastic strain was induced by local thermal expansion due to laser irradiation. Key Words:Grain-oriented 3%-Si steel, Laser pulse irradiation, X-ray stress measurement, Single crystal, Residual stress