Magnetic aging anisotropy of a semi-processed non-oriented electrical steel

Electric motor cores are made of semi-processed non-oriented electrical steels. These steels are processed in such a way that the final heat treatment, which causes decarburization and improves magnetic properties, is made by the core producers. Depending on the effectiveness of this heat treatment, the core can heat during motor operation, causing carbide precipitation/coalescence in the metallic matrix, impairing the magnetic properties of the steel. This phenomenon is known as magnetic aging. The present study shows that magnetic aging takes places under anisotropic conditions. In a semi-processed steel, the largest magnetic loss variation occurs at 0°, around 40° and 90° in relation to the rolling direction. This anisotropy can be attributed to the crystallographic structure of this kind of material, in combination with the oriented precipitation of the carbides during aging.