Increasing the Productivity of Laser Powder Bed Fusion for Stainless Steel 316L through Increased Layer Thickness
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JMEPEG https://doi.org/10.1007/s11665-020-05334-3
Increasing the Productivity of Laser Powder Bed Fusion for Stainless Steel 316L through Increased Layer Thickness Alexander Leicht
, Marie Fischer, Uta Klement, Lars Nyborg, and Eduard Hryha
Submitted: 4 August 2020 / Revised: 24 October 2020 / Accepted: 7 November 2020 Additive manufacturing (AM) is able to generate parts of a quality comparable to those produced through conventional manufacturing, but most of the AM processes are associated with low build speeds, which reduce the overall productivity. This paper evaluates how increasing the powder layer thickness from 20 lm to 80 lm affects the build speed, microstructure and mechanical properties of stainless steel 316L parts that are produced using laser powder bed fusion. A detailed microstructure characterization was performed using scanning electron microscopy, electron backscatter diffraction, and x-ray powder diffraction in conjunction with tensile testing. The results suggest that parts can be fabricated four times faster with tensile strengths comparable to those obtained using standard process parameters. In either case, nominal relative density of > 99.9% is obtained but with the 80 lm layer thickness presenting some lack of fusion defects, which resulted in a reduced elongation to fracture. Still, acceptable yield strength and ultimate tensile strength values of 464 MPa and 605 MPa were obtained, and the average elongation to fracture was 44%, indicating that desirable properties can be achieved. Keywords
additive manufacturing, EBSD, laser powder bed fusion, productivity, stainless steel, tensile properties
1. Introduction Laser powder bed fusion (L-PBF) is a manufacturing process used for producing metal components by repeatedly applying thin layers of powder and selectively melting them on top of one another using a high-energy laser to create the final geometry (Ref 1). This process allows for the fabrication of complex near-net-shape parts with high accuracy and good quality. With proper handling, it is possible to produce almost fully dense components with properties that are comparable to those from conventional methods or, in some cases, even better (Ref 2). Different sectors, such as aerospace, energy, medical, marine engineering, and automotive, have found L-PBF to be an appealing option given its design freedom and improved mechanical properties. However, one main challenge with LPBF is the relatively low productivity related to a low build speed and consequently a high manufacturing cost. Therefore, L-PBF is used primarily for high-end components, most often within the aerospace or medical industry, in which the production volumes are relatively small, and high costs are acceptable (Ref 3-5). Most of the research and development on the L-PBF processing of stainless steel 316L has so far focused on adjusting the process parameters to increase part quality, which Alexander Leicht, Marie Fischer, Uta Klement, Lars Nyborg, and Eduard Hryha, Department of Industrial and Material Science, Chal
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