Influence of roughness and subsurface porosity on the fatigue life of AlSi10Mg produced by Laser Powder Bed Fusion
Camille van der Rest, Rodrigo Arturo Manzano Navarrete, Aude Simar, Olivier Poncelet
Abstract
Porosity and poor surface quality are critical defects in Laser Powder Bed Fusion (L-PBF) that significantly impact mechanical performance, particularly under cyclic loading. To enhance fatigue resistance without relying on time-consuming post-processing, process optimization is essential. This study investigates the influence of roughness and subsurface porosity on the fatigue behavior of net-shaped, vertically built AlSi10Mg samples by tailoring contour parameters. Three sample sets were intentionally produced: (i) with a rough surface, (ii) with a smooth surface, and (iii) with a smooth surface and subsurface keyhole pores. Each set was evaluated in different conditions: as-built, mirror-polished, and sandblasted. Results show that optimizing contour strategies improves fatigue life but remains insufficient on its own. Post-processing, particularly sandblasting, significantly enhances fatigue performance. Surprisingly, subsurface keyhole pores do not appear to be as detrimental as surface roughness in fatigue failure. However, lack-of-fusion defects, when present near the surface, are critical stress concentrators and can drastically reduce fatigue life. These findings emphasize the critical role of surface state in fatigue behavior and provide insights for L-PBF process optimization in high-performance applications. • Lack-of-fusion defects are detrimental for fatigue, especially in the contour. • Keyholing contour parameters give low roughness and improved fatigue life. • Even with optimized contours, fatigue life remains low without post-processing. • Sandblasting cannot improve roughness when keyholing contour parameters are applied. • Keyholes in the contour are not harmful for fatigue, except if polishing is applied.