Magnetic properties of fine-grained doubly oriented Si steel sheets

The magnetic properties of fine-grained doubly oriented Si steel sheets of 0.25–0.35 mm in thickness have been investigated. The doubly oriented Si steel sheets with grains of about 0.5 mm in diameter showed a large induction B8 of about 1.9 T as well as a 35% smaller core loss than the previously studied coarse-grained doubly oriented materials. This decrease in core loss associated with the grain size reduction is primarily due to a large decrease in eddy current loss. The core loss was further decreased by applying tensile stresses and by a reduction in sheet thickness. A tensile-stressed 0.25-mm-thick material showed a small core loss of 0.82 W/kg at 1.7 T and 50 Hz. The material also showed relatively small core losses under alternating fields below 500 Hz.