Influence of modulated laser power on the surface topography and microstructure in the Laser Powder Bed Fusion process

Laser powder bed fusion (L-PBF) with continuous or pulsed laser power is used to manufacture 3D metal parts. Due to the layer-wise manufacturing, the surface topography of the single layers is crucial for the manufacturing of complex components. Especially in multi-material processing, the surface topography is the decisive factor for achieving targeted material delineation and avoiding intermetallic phases. This research work investigates the influence of a novel periodic high-frequency laser power modulation in the L-PBF process. Aim is to combine the advantages of continuous (high build rate) and pulsed laser power (reduced energy input) in one laser operation mode. It can be shown that the modulated laser power enables the manufacturing of dense specimens with smooth surfaces made of the brittle soft magnetic material FeSi6.7. Manufactured specimens are investigated with an optical microscope, white light interferometer and polished materialographic cross-sections. Correlations between laser power parameters and specimen properties are investigated and elucidated.