It is well known in the literature that the fatigue response of parts produced through Additive Manufacturing (AM) processes is mainly controlled by the defect population and, in particular, by the defect size. Therefore, for a proper and safe design of AM components subjected to critical fatigue loads the defect size in the component volume should be known or reliably estimated. To this aim, the X-ray microcomputed tomography (microCT) technique can be usefully used for a non-destructive assessment of the most critical defect in AM parts and, consequently, for the estimation of the fatigue response. However, this technique is rarely adopted since it is very expensive and time consuming. An alternative faster and cheaper method considers the defects originating the fatigue failure of small specimens during laboratory tests. In this second case, size-effect must be carefully taken into account. Investigation of size-effects on the fatigue response of AM parts has been rarely studied in the literature, especially if the Very-High-Cycle Fatigue (VHCF) region is considered.
The present paper aims at assessing size-effects on the VHCF response of AlSi10Mg specimens produced through the Selective Laser Melting (SLM) process. Ultrasonic fatigue tests have been carried out on Gaussian specimens with large risk-volume and hourglass specimens built in horizontal direction. Fracture surfaces have been observed by using the Scanning Electron Microscope in order to investigate the failure origin. Size-effect has been finally statistically assessed by considering the models proposed in the literature.