Influence of Contour Scan Variation on Surface, Bulk and Mechanical Properties of LPBF-Processed AlSi7Mg0.6

Abstract

Metal additive manufacturing technologies have great potential for future use in load-bearing aerospace applications, requiring a deeper understanding of mechanical performance and influencing factors. The objective of this study was to investigate the influence of contour scan variation on surface quality, tensile and fatigue strength for laser powder bed fusion samples made of AlSi7Mg0.6 material and to create high-quality as-built surfaces. The samples were produced with identical bulk and different contour scan parameters to accommodate the investigation of the impact of as-built surface texture on mechanical properties. The bulk quality was evaluated by density measurements according to Archimedes’ principle and tensile testing. The surfaces were investigated using the optical fringe projection method, and surface quality was assessed by the areal surface texture parameters Sa (arithmetic mean height) and Sk (core height, derived from material ratio curve). Fatigue life was tested at different load levels, and the endurance limit was estimated based on a logarithmic-linear relation between number of cycles and stress. All samples were found to have a relative density of more than 99%. Surface conditions distinctive in Sa and Sk were successfully created. The resulting mean values of the ultimate tensile strength σult are between 375 and 405 MPa for 7 different surface conditions. It was confirmed that the influence of contour scan variation on bulk quality is insignificant for the assessed samples. Regarding fatigue, one as-built condition was found to perform as well as surface post-processed parts and better than the as-cast material (compared to literature values). The fatigue strength at the endurance limit for 106 cycles is between 45 and 84 MPa for the three considered surface conditions.

Impact of Boundary Parameters Accuracy on Modeling of Directed Energy Deposition Thermal Field

“…The layer height is higher in the DED process (close or larger than 1 mm) than in the L-PBF one (usually a few tens of µm [24,25]) and smaller than that in the case of WAAM (above 1 mm [26]). Nevertheless, for any real part manufactured by a LPBF, DED, or WAAM process, the length of the laser path is of a magnitude larger than the equivalent diameter of the track (for this study, the typical transversal dimensions of a track were about 0.75 mm, while the total path was about 40,000 mm long).…”

Comparison of Optical and Stylus Methods for Surface Texture Characterisation in Industrial Quality Assurance of Post-Processed Laser Metal Additive Ti-6Al-4V

“…Fringe projection was used for metal AM surface topography measurement by Whip et al [ 23 ] and Zheng et al in comparison with focus variation microscopy [ 43 ]. We previously applied the method for areal characterisation in relation with fatigue data [ 52 , 53 ].…”