Magnetic properties of high-permeability thin gauge non-oriented electrical steel sheets

Magnetic properties of high permeability thinner gauge non-oriented electrical steel sheets are investigated from the viewpoint of applications in the audio frequency range. The steel sheets 0.75 mass% Si - 0.3 mass% Al (0.20, 0.35 and 0.50 mm in thickness) were prepared, including the hot-band annealing prior to the cold-rolling for the purpose of controlling the texture. The stress-relief annealing was carried out before the characterization. The flux density at applied field of 5000 A/m is 1.76 T for 0.2 mm-thick sheet. The decrease of the thickness from 0.5 mm to 0.2 mm results in the 67% reduction of the core loss measured at the flux density of 1.0 T and the frequency of 1 kHz. The core losses measured at 1.0 T, 400 Hz and 1.0 T, 1 kHz are 15.7 W/kg and 57.9 W/kg. The RMS exciting force of the developed sheet (0.2 mm in thickness) at 1.6 T, 400 Hz was about one-fourth as large as that of a conventional 3 mass% Si steel sheets. Their results would indicate that such high permeability thin gauge steel sheet could be utilized in the audio frequency application, in particular, in the motor cores of the electric vehicles.