Microstructure, Magnetic Properties, and Performance of Fe-6.5Si Soft Magnetic Core Produced by Laser Powder Bed Fusion

High-silicon electrical steels containing 6.5 wt.% Si (Fe-6.5Si) are promising materials for high-efficiency electric motors because of their high electrical resistivity and low core loss. However, the intrinsic brittleness of high-silicon steels limits their formability using conventional fabrication methods, such as cold rolling, pressure forming, and sintering, making it difficult to fabricate three-dimensional (3D) soft magnetic cores for axial-flux permanent magnet (AFPM) motors. Additive manufacturing has recently attracted attention as an effective approach for producing complex magnetic components. In particular, laser powder bed fusion (LPBF) enables the fabrication of geometrically complex structures through localized melting and rapid solidification of metal powders. During LPBF, rapid thermal cycling can generate unique microstructures that influence the magnetic properties of fabricated materials. In this study, Fe-6.5Si samples were fabricated using LPBF, and their microstructure and magnetic properties were investigated. In addition, a complex-shaped 3D core was successfully fabricated by LPBF, and the performance of an AFPM motor equipped with the LPBF-fabricated core was evaluated. The results show that the LPBF-fabricated core can provide superior performance-to-weight efficiency for lightweight motor applications.