Atsuhito Honda

Nonoriented electrical steel sheet with low iron loss for high-efficiency motor cores

A new material was studied for high-efficiency motor cores that need higher magnetic flux density, lower iron loss, and lower mechanical hardness. Excessively high Si content tends to decrease magnetic flux density of nonoriented electrical steel sheets. The composite addition of rare-earth metals (REM) and Al into molten steel was found to make inclusions coarse and remarkably improve grain growth during stress relief annealing, which resulted in decreased iron loss. A new nonoriented electrical steel sheet (50RMA350) with Si, Al, and REM has been successfully developed to give a higher efficiency to inverter drive model motors than a conventional material.

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...

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.