Dependence of the cut region on the magnetic losses of a non-grain-oriented Fe-Si steel

The final cutting process of electrical steel sheets is well-known to negatively impact their magnetic properties. Specifically, mechanical cutting introduces structural changes in the cutting region that adversely affect the steel's performance by increasing its overall magnetic loss. In this work, a non-grain oriented electrical steel was studied, and the effects of cutting clearance and the number of cuts in the material sheets (zero cut or single strip, cut in half and separated into 3 parts) on the relative permeability and different loss components (hysteresis, classical, and excess) were evaluated across a wide range of frequencies (10 to 400 Hz) and maximum polarization values (0.1 to 1.5 T). Our observations indicate that hysteresis loss is the most prominent among all the loss components, regardless of the magnetic polarization and throughout the frequency range up to 400 Hz for all cutting conditions. Above this value, the classical loss begins to dominate. However, interestingly, for samples with the greatest number of cuts (3 parts), Pe becomes greater than Pc and no inversion is observed in the entire range of polarizations studied. These findings demonstrate that each physical mechanism has a dominant role within a specific frequency range of a device's operation. Additionally, we noticed that increasing the cutting clearance from 0.01 mm to 0.03 mm resulted in a roughly 14% increase in total loss. This increase can be attributed to the impacts on the microstructure caused by the larger cutting clearance.