Texture components and magnetic properties of laser powder bed fusion fabricated near grain-oriented and near non-oriented silicon steel

Abstract

Silicon steel is a widely used soft magnetic material that requires different texture components for different applications, typically classified as grain-oriented or non-oriented. However, the methods of fabricating such types of silicon steel via laser-powder bed fusion (LPBF) have not been fully investigated. In this study, near grain-oriented and near non-oriented Fe-3.5 wt.%Si silicon steel is fabricated using LPBF by controlling processing parameters. Different textures are investigated using electron backscatter diffraction (EBSD), and the morphology of the molten pool is characterized by optical microscopy (OM) and scanning electron microscopy (SEM). Magnetic properties are measured with alternating current (AC) method. The results show that reducing both the linear energy density (LED) and laser power leads to a change in the side morphology of the molten pool from large, flat, and well-overlapped to small, protuberant, and less-overlapped, resulting in an extremely strong θ-fiber texture or a random distribution of grain orientations, respectively. Additionally, reducing both the laser power and scanning speed causes the top morphology of the molten pool to change from teardrop to elliptical shape at the trailing edge, resulting in a shift in the angle between the 〈001〉 of grains in the θ-fiber texture and the scanning direction from 45° to 30°. Samples with fewer defects (i.e., larger grain size and fewer pores) and a larger area fraction of 〈001〉//H exhibit higher permeability, although this superiority is not so significant due to residual stress and high dislocation in the as-built samples. This study provides insight into the relationship between processing parameters, texture evolution, and magnetic properties in LPBFed silicon steel.