DEVELOPMENT OF DOMAIN REFINED GRAIN-ORIENTED SILICON STEEL BY GROOVING

Recently a heat-proof magnetic domain refining technique has been developed which is characterized by the introduction of grooves on a surface of steel sheet after final cold rolling. In this paper, magnetic properties and the domain refining effect of grooving are investigated. A grooving process is constituted by resist printing on the surface of steel sheets after final cold rolling and succeeding electrolytic etching. The grooves were introduced almost perpendicular to the rolling direction of steel sheets. The width and depth of each grove are about 200 and 20 mum, respectively. With this newly developed method, about 10% reduction in iron loss was achieved and less than 0.34 W/lb at 1.5 T, 60 Hz was obtained. Using this new material, the iron loss of wound core transformers can be reduced by about 10% as compared with nongrooved material. Domain width was dramatically reduced by grooving, which caused the reduction of eddy current loss. This reduction is considered to be caused by the demagnetizing field effect due to free poles in the vicinity of grooves. It was clarified that in grooved sheets the magnetization on the ungrooved surfaces proceeded faster than on the grooved surfaces and therefore, hysteresis loss and magnetizing characteristics did not deteriorate by grooving.