Toward enhanced energy efficiency in LPBF of Nickel alloy 718 by using ring-shaped laser beams

Abstract The use of additively manufactured metal components is rapidly expanding, prompting ongoing research into more advanced and efficient processing strategies. Beam shaping is one of the latest trends in Laser Powder Bed Fusion (LPBF). As a matter of fact, some authors reported the effectiveness of this approach in producing parts with tailored microstructure and properties, while on the other hand, very little has been said about the sustainability implications of using ring-shaped beams in LPBF. This work aims to bridge some of the gaps of knowledge existing in this regard, thus investigating the influence of different beam shapes on energy consumption and process stability, while boosting productivity. Four laser beam shapes were investigated, ranging from the traditional full Gaussian distribution—used as the reference in this study—to a full ring configuration. Nickel alloy 718 was selected as the feedstock material due to its growing adoption in the aerospace sector, where productivity and sustainability are critical factors for additively manufactured components. Mechanical testing was conducted to assess process performance, alongside considerations of sustainability. The energy consumption of the laser system, as well as the building time, has been recorded to properly calculate the specific energy consumption (SEC) and the productivity of the laser system used, selecting the different modalities. Surface roughness, density, microhardness, and microstructure of the printed samples have been chosen as quality indicators of the printed parts. Among the main experimental findings is that the full ring modality improved productivity of the laser system by approximately 46% and reduced its SEC by 16% compared to the conventional full Gaussian beam, despite an approximate 29% increase in surface roughness. Also, the outcomes confirmed the potentiality of beam shaping in tailoring the microstructure of metal alloys parts manufactured by LPBF.