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%.

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The effect of annealing temperature on grain growth, texture development and magnetic properties of Al-free and Al-1% added non-oriented electrical steel were investigated. Normal grain growth occurred in Al-free steel. On the other hand, abnormal grain growth occurred in Al-added steel which was annealed at 800°C for 24h. Precipitates in these two steels were different. TiN precipitated in Alfree steel, but in the case of Al-added steel, AlN and TiC precipitated. The TiC in Al-added steel was so fine that it inhibited the normal grain growth and finally caused the abnormal grain growth. Main textures of both steels were near {111}<112>, but the intensity of near {111}<112> in the abnormal grain growth was higher than that in the normal grain growth. Magnetic flux density (B50/Bs) was decreased by the grain growth. Especially B50/Bs in the abnormal grain growth was lower than that in normal grain growth. B50/Bs in these steels can be estimated by their three-dimensional textures in vector method.

Grain size and texture are very important for controlling the magnetic properties in non-oriented electrical steel. Grain size and texture are closely related because the texture usually changes during grain growth. In this study, texture changes with grain growth in non-oriented electrical steel are investigated. Two kinds of materials, Sample A and Sample B, were prepared in order to study the differences of the texture. Sample A, Fe-0.5wt%Si, is not annealed before cold rolling. Sample B, the same chemical composition as Sample A, is annealed before cold rolling. In Sample A, the {111} texture component increases markedly during grain growth. By contrast, in Sample B, the increase in {111} is less pronounced. The recrystallized orientations in both Samples are analyzed, and computer simulation is used to attempt to explain the texture changes during grain growth. In the case of Sample A, the simulations reproduce the experimental result well; for Sample B, however, the simulations do not agree as well. The microstructures before annealing exhibit strong alignment of the orientations, which will require a new approach to building the digital microstructures for instantiation of the simulations.