Improved crystallographic texture by low-temperature heat treatment of non-grain oriented silicon steel subjected to mechanical cutting

The mechanical cutting process is a critical step in the manufacturing of electrical steel components, often inducing localized plastic deformation and lattice distortion that significantly compromise magnetic performance. To mitigate these effects, post-cutting heat treatments are employed to promote microstructural recovery and optimize crystallographic orientation. This study investigates the influence of annealing temperature (700 ◦ C and 900 ◦ C) on the cutting-affected zone (CAZ), crystallographic texture, and magnetic properties of a non-oriented (NGO) electrical steel. Characterization was performed using microhardness profiling, Electron Backscatter Diffraction (EBSD), and magnetic loss separation based on the Bertotti model over a frequency range of 10–400 Hz. Results indicate that the CAZ extends approximately 400 µ m from the edge. The heat treatments significantly recovered the magnetic properties, with the 700 ◦ C condition resulting in a 39.7% reduction in total magnetic losses for the samples with the highest cut density (from 20.72 W/kg to 12.49 W/kg at 1.0 T/400 Hz). While the 900 ◦ C treatment achieved a similar reduction in total losses (12.64 W/kg), EBSD and Orientation Distribution Function (ODF) maps reveal a critical textural degradation at this higher temperature. The volume fraction of the magnetically favorable Cube texture ({100} < 001 > ), which is approximately 51% after annealing at 700 ◦ C, drops to 18% at 900 ◦ C. This shift is accompanied by a increase in the Gamma fiber ({111} < uvw > ), increasing from 4% to 12%. These results indicates that while 900 ◦ C provides mechanical softening, it triggers a textural shift that compromises the quality of the magnetic restoration, making 700 ◦ C the good balance for high-frequency applications. The study highlights that annealing at temperatures below 750 ◦ C offers a superior balance for NGO steels, facilitating strain relief while pinning desirable textures, which has direct implications for the efficiency of high-performance electrical machines.