Hiroshi Shimanaka

Recent development of non-oriented electrical steel sheets

Abstract The magnetic properties required of non-oriented electrical steel sheets are discussed from the viewpoint of reducing core losses in generators and motors by taking into consideration the magnetic flux distribution in the core. The methods of improving magnetic properties are critically reviewed with respect to the alternating, rotational and high-frequency losses as well as permeability. The amorphous and high-silicon ribbons were viewed as potential core materials.

Ribbon-form silicon-iron alloy containing around 6% silicon

By a roller quenching method, XSi-(100-X)Fe ribbons ( 6.0 \leq X \leq 7.0 ) in the crystalline state were prepared. The size of them was 20 to 150μm in thickness, 2 to 25 mm in width and 5 to 10 m in length, and after annealing all of them were mechanically very soft so as to be bent 180°. In the grain structure of the as-prepared ribbons the columnar grains about 10μm in diameter were observed to grow from the surface to the middle part of the ribbon thickness. The texture of them have

A new non-oriented Si-steel with texture of {100} 〈ovw〉

Abstract A new non-oriented Si steel with a crystallographic texture of nearly {100} 〈ovw〉 has been developed by the addition of a small amount of Sb and by the employment of annealing the hot rolled sheets and one staged cold rolling.

Rapidly quenched ribbon-form silicon-iron alloy with high silicon concentration

Abstract By rapid quenching techniques polycrystalline silicon-iron ribbons Si x Fe 100- x (3.8 ⩽ x ⩽ 9.3 in weight), 20–150 μm thick and 2–25 mm wide were prepared. After annealing, the grains about 200 μm and a columnar structure with [100] perpendicular to the ribbon plane were observed, in a Si 6.5 Fe 93.5 ribbon, the coercive field was 80 mOe.

Magnetic properties of roller-quenched high silicon steel ribbons

Abstract The magnetic properties of high silicon steel ribbons prepared by the roller-quenching method were investigated, and this new material was considered to offer the potential of reducing core losses of electrical machines and power transformers.

Effects of surface coatings on domain structure in grain oriented 3% Si-Fe

The effects of surface insulating coatings on magnetic properties in commercial highly grain oriented Si-Fe sheets are shown on the basis of domain observation using a high voltage SEM. The average 180° wall spacing in grain oriented Si-Fe sheets with the coatings could be expressed semiempirically as a function of tilt of the [001] out of the sheet plane and grain length. Iron loss and 180° wall spacing were slightly reduced by the application of a stress coating. The formation of a forsterite coating resulted in an increase in iron loss and a significant decrease in 180° wall spacing. The observation of dynamic domain patterns showed that the forsterite coating made the induction inhomogeneous among the grains. This would increase the iron loss even though the 180° wall spacing was reduced.

Influence of toroid radius on magnetic properties of iron-based amorphous alloys and 6.5WT%Si-Fe rapidly solidified ribbons

Iron-bases amorpnous alloys (Fe 78 B 13 Si 9 ), crystalline 6.5wt% Si-Fe rapidly solidified ribbons and 3wt% silicon steel sheets were wound in to toroid cores of 25mm width and 5∼35mm radius. A stress of 130MPa was applied to the amorphous ribbons by 130MPa. The AC and DC properties were measured, and then the magnetic domain configurations were observed by SEM. The iron loss of amorphous alloys increased inversely proportional to the toroid radius before Stress Relief Annealing (SRA), but were almost independent of radius after SRA. The results on 6.5wt%Si-Fe ribbons were similar to those of amorphous ribbons. The increase in losses were due to hysteresis loss in both cores. A similar effect of the toroid radius was shown on the magnetic domain configurations. The 180° and cross domain configurations were observed on both surfaces of flat ribbons before SRA. A wide 180° domain was observed after SRA. When the specimen was bowed to various radii, wide 180° domains were observed in the longitudinal direction on the convex side and narrow 180° domain was observed in the transverse direction on the concave side. The iron loss was reduced by a factor of 2 with increasing applied stress up to 70MPa before SRA and up to 25MPa after SRA.

Influence of small amounts of aluminum and sulfur on magnetic properties in amorphous ribbons

Small amounts of metallic aluminum and aluminum oxide or ferrosulfur were added to the Fe-B-Si alloys. The specimens were prepared with 10∼20mm width and approximately 30μm thickness. Annealings were performed in a magnetic field up to 425°C for 60min in vacuum. The minimum iron loss after annealing was increased by the factor 1.1 ∼ 1.2 by the addition of aluminum and aluminum oxide or sulfur. The annealing temperature which gives the minimum less was 375°C for Fe-B-Si-0.04at%S ribbons, 350°C for Fe-B-Si-0.008at% Al and Fe-B-Si-0.04at%S ribbons. The magnetic domain patterns were observed by SEM.

High flux density silicon-iron ribbons

Silicon iron ribbons with silicon concentration lower than 4 wt% were prepared by a rapid quenching roll method, and the size of ribbons obtained were 2∼4 mm in width and 40∼60 μm in thickness. The grains grew to about 2 mm and the ribbons had

Effect of several stress inducing coatings on magnetostriction property of a high induction 3% silicon steel

The stress inducing behavior of various coatings by applying coating solutions mainly composed of colloidal silica and one of (Mg,Ca,Sr,Ba,Fe,Zn and Al) phosphates onto high permeability 3% silicon steel sheet (RG-H) were examined. The results of magnetostriction measurements showed that the coating formed by colloidal silica and Mg phosphate mixed solution gave the largest tensile stress to the steel sheets and that the coating by colloidal silica and Al phosphate was second to it. Though the thermal expansion coefficients (α) which were measured on sintered bodies prepared from dried reagents of coating solutions were about 4×10-6for both coatings containing Al and Mg phosphate, X-ray diffraction peaks of exfoliated powder from coating containing Al phosphate showed the presence of α-cristobalite even after one minute baking at 800°C and showed a remarkable increase of it after the stress relief annealing of 800°C-5h in N 2 atm. The presence of α-cristobalite seemed to be harmful because of its large α value of 53×10-6below 300°C. It was concluded that the good magnetostriction property of the coating formed by colloidal silica and Mg phosphate was due to the amorphous structure with low α value even after the stress relief annealing.