Effects of Magnetic Field Applied During Heat Treatment on Magnetic Properties of Non-Oriented Electrical Steel Sheets

Abstract

  To improve the magnetic properties of non-oriented electrical steel sheets, the effects of applying heat treatment in a magnetic field on controlling the crystallographic orientation were studied. The heat treatment temperature was controlled to be 1023, 1123, and 1273 K. The magnetic field applied during the treatment was parallel to the rolling direction of sheet samples, and the magnetic field strength was 10 T at maximum. The samples heat treated in a magnetic field under the temperature condition of 1123 K or higher showed a remarkable change in magnetic properties as the textures changed. Even when a magnetic field was not applied, the grain growth was accelerated by heat treatment, iron loss was reduced, and permeability under low excitation conditions was improved. However, the permeability at 1.6 T or higher decreased. In this paper, it is shown that iron loss could be further reduced by applying a strong magnetic field during the cooling step of the heat treatment. It is also found that applying a strong magnetic field throughout the heat treatment, i.e. heating and cooling, inhibited grain growth, increased iron loss, and decreased magnetic permeability.