Magnetic Anisotropy and Loss Separation in Grain Oriented Electrical Steels (Goes)

Grain oriented electrical steel (GOES) are mainly used on magnetic cores of transformers. Such cores are built aiming to minimize the magnetic losses and maximize the material's magnetic induction by magnetizing the material parallel to the rolling direction (RD) in detriment to the transverse direction (TD), since the grain oriented electrical steel (GOES) are highly anisotropic materials. However, it is known that there are parts in the transformer's magnetic core where there are significant portions of material magnetized in a direction other than the RD, such as the TD. A better understanding of the magnetic losses and the magnetization mechanisms of grain oriented electrical steels (GOES) both in the RD and the TD can be of great value to the proper selection of materials and to optimizing the transformer design. The present paper investigates the relationship between the crystallographic texture (B800) of the grain oriented electrical steels (GOES) and its different magnetic losses (i.e., total loss, eddy loss, hysteresis loss and anomalous loss) both for the samples cut in the RD and TD in different steel grades of conventional grain oriented electrical steels (CGO) and high permeability grain oriented electrical steels (HGO). The analyses show, regarding the total loss (Pt), an inversely proportional relationship between the values of total loss (Pt) and B800 was found in the RD indicating the existence of a relationship between the degree of alignment of the direction [001] in relation to the RD and the magnitude of these two properties. The same relationship was not found on TD, which reinforces the complex character of the magnetization process of the GOES in the TD. Furthermore, steels with lower total loss on RD do not necessarily have lower total losses in TD. Regarding the eddy loss (Pe), as an isotropic property mainly related to the thickness and resistivity of the sample, it was not found any direct correlation with the crystallographic texture of the steel. The hysteretic loss (Ph) and anomalous loss (Pa) are, at different levels, shown to be strongly affected by the steel texture (B800). Finally, it was verified that due to the high phenomenological complexity of the magnetic anisotropy of the grain oriented electrical steels, it is not valid to assume that an electrical steel with lower magnetic losses (Pt) necessarily has a higher magnetic anisotropy.