Aerospace Technic and Technology

Recently, the production of metal products has become more adaptable and rapid because of the use of 3-D technologies based on layer-by-layer manufacturing. The quality of products produced using selective laser melting (SLP technology) depends on many factors, which can be divided into main groups: equipment, materials, processes, details, and finishing. To ensure high-quality products, a systematic approach is necessary. Subject of research. Patterns of influence of changes in combinations of the main parameters of the manufacturing process (scanning strategy, distance between tracks, specific power of the process, scanning speed, power) of various elements (main body, border, post-border) of products manufactured using SLP technology on their quality (integrity and surface roughness). Purpose. Development of recommendations for border and post-border printing modes for 316L stainless steel with a layer thickness of 30 μm at different distances between tracks and with varying laser beam scanning speeds. Methods. For research purposes, samples of 10×10×5 mm were prepared using SLP technology from AISI 316L austenitic steel powder. The main body of the test samples was produced with constant parameters: layer thickness 30 μm, power 100 W, scanning speed, 1700 mm/s; distance between tracks, 0.05 mm; calculated specific energy density is 39.21 J/mm³, continuity ~ 99, 9%. The test samples of groups A, B, and C differed according to the scanning strategy (Out2In or In2Out) and the distance between the boundary tracks. Test samples of groups D, E, and F were made with constant power parameters of 100 W and the distance between the border tracks of 0.05 mm and with variable scanning speed parameters for group D 2.6...1.75 m/s; for group E 2.6...1.55 m/s; for group F 3.0...1.55 m/s. Samples were printed on an Alfa-150 3D printer by ALT Ukraine LLC. Etching of the structure was carried out in Kalling’s solution, and analysis of the microstructure was carried out using an AxioVert 200MMat optical microscope. Roughness control was performed using BioBase 220R with a constant control zone of 1.25 mm. Results. It was established that the borders of samples of groups A and C printed in the range of specific energy density ≈27-33 J/mm3 have thin borders that do not protrude and have no visible deviations. Roughness control showed that test samples A3, A4, C4, D5, E1, E2, and F6 had roughness values in the range of 9.7...11.2 microns. When comparing the obtained data with the manufacturing parameters and microstructure analysis, it was established that to achieve high continuity with minimal roughness in the finished products on the surface, it is necessary to apply the parameters in such a way that the post-contour manufacturing parameters energetically fluctuate in the range of ± 4 J/mm³ from the specific energy density main body.

selective laser melting; AISI 316L; main body; post-border; border; roughness

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