Effect of Laser Energy Density on Surface Morphology, Microstructure, and Magnetic Properties of Selective Laser Melted Fe-3wt.% Si Alloys

To study the effect of the laser energy density (LED) on surface morphology, microstructural evolution, and magnetic properties of Fe-3wt.% Si alloy, the alloy was manufactured via selective laser melting (SLM) technology. The SLM Fe-3wt.% Si parts were characterized by a series of advanced material methods including a 3D profilometer, optical microscope, scanning electron microscopy, and vibrating sample magnetometer, etc. The results show that no obvious microcracks exist in the SLM Fe-3wt.% Si parts. With the LED increases, the porosity rate and the surface roughness of the SLM Fe-3wt.% Si parts decrease. Furthermore, the cross-sectional microstructure of the SLM Fe-3wt.% Si parts is a typical columnar structure with an orientation growth building direction. The microhardness of each SLM Fe-3wt.% Si sample is higher than 200 HV0.1. Besides, the coercivity of SLM Fe-3wt.% Si parts decreases first and then increases with the increase in the LED. The specimen with a LED at 300 J/m exhibits better comprehensive magnetic properties than others. It could be concluded that the magnetic properties of SLM Fe-3wt.% Si alloys are affected by the synergistic effects of manufacturing defects and internal stress.