As‐built surface quality and fatigue resistance of Inconel 718 obtained by additive manufacturing
Federico Uriati, Gianni Nicoletto, Adrian H. A. Lutey
Abstract
It has been recognized that parts produced by additive manufacturing with surfaces in the “as-built” state exhibit reduced fatigue properties. On the other hand, post-process surface finishing is expensive and often unfeasible due to the complexity of parts. Therefore, surface quality parameters must be considered when designing as-built parts for structural applications. This work investigates the as-built surface topography of Inconel 718 samples manufactured via laser powder bed fusion (L-PBF) with three different production systems (SLM 280HL, EOS M290, and RENISHAW AM250) and discusses their respective experimental fatigue behavior. The aim of the investigation is to identify a link between the fatigue response of L-PBF IN718 alloy without post fabrication finishing and the surface morphology; a preliminary comparison among the main surface roughness parameters and the fatigue strength is reported and further investigations are planned to find a univocal correlation. Samples with a mean height (Sa) of approximately 20 μm exhibit lower fatigue strength than those with Sa of approximately 5 μm. Skewness (Ssk) and kurtosis (Sku) are instead found to be discriminating parameters when comparing surfaces with relatively low surface roughness (Sa 5 μm), with higher values of Ssk and Sku associated with inferior fatigue performance.