Effect of stretching during annealing and decarbonizing treatment on the magnetic properties of grain-oriented electrical steels

ABSTRACT The ability of the electrical steels to amplify an externally applied magnetic field is due to a strong texture induced during secondary recrystallization, the step in which grains with Goss orientation nucleate in the primary matrix. At this stage, normal grain growth is inhibited by a scattering of precipitated particles. The main objective of this research was to investigate the effect of stretching during the annealing and decarbonizing treatment on the magnetic properties of grain-oriented electrical steels with 3% Si. The study subjected grain-oriented electrical steel samples to heat treatment simultaneously to different tensile stresses. After the heat treatment, the samples were characterized by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The best results, in terms of core losses, were obtained for the sample treated without stretching. The presence and size of MnS and AlN precipitates were also found to significantly influence the magnetic properties. These results focused on the importance of controlling stretching during annealing to optimize the magnetic performance of grain-oriented electrical steels for applications in transformers and generators.