Keiji Sato

Localized magnetic properties in grain‐oriented electrical steel measured by needle probe method

The accuracy of a needle probe method in measuring localized magnetic properties of grain-oriented electrical steel sheets was investigated and its application studied. The measuring error for the localized flux density was determined to be less than 1.7% for a load on the needle tip lighter than 300 g when the yoke structure was symmetrical with respect to the sheet plane. The average of localized iron losses measured with the combination of a needle probe and a Hall probe was in linear relation to the overall losses in the sheet. This method revealed that the localized magnetic properties vary markedly from location to location inside the sheet, and that localized iron loss depends on the localized flux density, domain wall spacing, and yaw angle of grain orientation.

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 μm, 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 f...

Investigation on the domain refining effect in grain-oriented silicon steel

Conditions to maximize the domain refining effect were investigated using the plasma flame irradiation method. It was required to optimize the interval of plasma flame irradiated lines depending on the grain size of the sheet and to reduce the tilt angle of the sheet.

Effect of crystal orientation on the iron loss and magnetostriction in domain refined highly grain oriented Si steel sheets

Iron loss and magnetostriction in domain refined highly grain oriented Si steel sheets were investigated. The degree of grain refining effect on iron loss has been found to be significantly influenced by crystal orientation. This phenomenon is explained by that reappearance of lancet domains during magnetization is strongly influenced by the tilt angle of [001] axis from sheet plane.

Development of Heat-Proof Domain-Refining Technique in Grain-Oriented Si Steel

A heat-proof magnetic domain-refining technique has been developed which yields good results when applied to wound-core transformers, in which the iron loss suffered using non-refined material can be reduced by about 10%. The new technique is characterized by grooves introduced on the sheet surface after the final cold-rolling process.