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This paper discusses the possibility of iron loss reduction in non-oriented electrical steel (NO) sheets with a composition corresponding to JIS grade 35A210, and estimates the optimum iron loss from experimental data. The hysteresis loss of processed pure NO steel was decreased by 0.27 W/kg from the present 35A210 standard. The 0.35-mm-thick NO sheets with random {100} textures and the optimum crystalline sizes of polycrystals and without precipitation may decrease iron losses from 2.0 W/kg to 1.0 W/kg, because random {100} textures may reduce the effects of steel surfaces on iron losses and make coercive forces low, and optimum crystalline sizes minimize total iron losses. If pure NO sheets with random {100} textures are used in motors, the iron loss of a motor may become low, not only because those of the core materials are low, but also because the motor core characteristics improve as a result of uniform flux distributions due to the low coercive force and lower internal stress caused by magnetostrictions. The decrease in the hysteresis loss was about 20%, relative to the present 35A250 standard, in a 12-pole 9-slot motor where a core made of pure NO was excited by a NdFeB bonded permanent magnet, although the decrease in the hysteresis loss of the core material was only about 18%.

The influence of purity and cooling-rate on the microstructure of hot-forged pure irons was investigated by using two kinds of pure irons. One was K-Iron of 99.981 mass% purity and the other was M-Iron of 99.993 mass% purity. After forging at 1263 K, above the α-γ transformation temperature, the specimens were immediately cooled to room temperature at various cooling-rates: by water-quenching, oilquenching, air-cooling, ash-cooling, and furnace-cooling. The microstructure of forged iron was strongly affected by the purity and the cooling-rate. It should be emphasized that in M-Iron columnar grains grew in parallel to the forging direction independent of the coolingrate. On the other hand, equiaxed grains were formed in all specimens of K-Iron forged at 1263 K. On both M-Iron and K-Iron, α-grains became larger with decreasing cooling-rate. The crystal orientation of α-grains on the forged plane of each specimen was measured by electron back-scattering diffraction-pattern method. On the forged plane of M-Iron, {101} of α-grains was predominant in the case of water-quenching and {111} or {221} was predominant in the other cases; on the other hand, the crystal orientation in K-Iron was random at all cooling-rates. Metallurgical factors controlling these characteristic microstructures in M-Iron were discussed in terms of growth of recrystallized of α-and γ -grains, mobility of γ /α interface, nucleation site and cooling-rate.

Influence of alloy purity on the tensile properties of Al-Si eutectic alloy castings has been investigated by using two kinds of the melted alloys: L-Alloy of 99.89 mass% purity and H-Alloy of 99.98 mass% purity. Although the base structure in both of alloys was composed of proeutectic -phase and eutectic structure, the eutectic structure of H-Alloy was finer than that of L-Alloy. Coarse crystals of plate-like silicon were observed in L-Alloy, while were not observed in H-Alloy. Based on the results of Brinell Hardness Test on the solidification structure, it was found that there was little difference of the hardness between the both alloys. Tensile tests were also performed in an atmosphere at room temperature. The elongation of H-Alloy was twice as large as that of L-Alloy, though the tensile strength of L-Alloy and H-Alloy were almost the same.

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