Effective domain and grain observation methods and iron losses in coated Si-Fe

Simple and effective domain and grain observation methods for highly oriented silicon steels with a tension inducing coating are presented using a ferromagnetic colloid technique and a new normal field generation method. Relations among domain spacings , iron losses, and grain boundary leakage fluxes in the coated or decoated sheets under various stresses are investigated utilizing the domain and grain observation technique in the grains with various tilt angles of the [001] out of the sheet plane. The minimum iron loss is measured in the grain with the tilt angle of approximately 2° as same as in the case of single crystals. An iron loss reduction technique for decoated sheets is tried by applying then removing high tensile forces of about 260 MPa ; about 11 % reduction in iron losses at 60 Hz, 1.7 T in the grain with about 2° tilt angle results.