Soft-magnetic behavior of laser beam melted FeSi3 alloy with graded cross-section

Abstract Laser beam melting of rotors of soft-magnetic iron-silicon-based alloys with a graded cross-section promises a significant reduction of power losses during the operation of electric motors. In this work, graded cross-sections are designed with slits at different positions. The novel approach to design and implement the graded cross-section in laser beam melted FeSi3 alloy is presented. It is based on an interaction between initial slit thickness defined in the CAD-model and down skin parameters, i.e. laser power and the number of layers processed with down-skin parameters. This approach allows precisely to influence the resulting slit geometry, i.e. porous or continuous gaps filled with unmolten powder, and their thickness. The effect of both, the slit geometry and their position in ring specimens on the power losses during magnetization and demagnetization at different frequencies is analyzed and discussed. The obtained results reveal the significance of proper design and accurate control of the slit geometry in parts with graded cross-section. As it is shown, cross-sections with slits designed as continuous gaps result in a reduction of up to 43 % regarding the power losses in comparison to the bulk cross-section. Thus, the presented method for grading the cross-section can be relatively simply implemented in the design and manufacturing process of laser beam-melted rotors and allows to improve their performance in comparison with bulk AM rotors.