HCF resistance of AlSi10Mg produced by SLM in relation to the presence of defects

Abstract

Being able to predict the fatigue resistance of parts produced by additive manufacturing (AM) is a very actual and frequent open issue. The qualification of AM structural parts needs a very costly and time consuming series of fatigue tests, on both samples and full-scale parts. A proper control of the AM process allows obtaining comparable and even better fatigue resistance than standard manufacturing. Despite this, the experimental results often show a large scatter, mostly due to the presence of defects. In this framework, this work summarizes a research activity aiming at modelling the high cycle fatigue (HCF) resistance in presence of defects, focusing on AlSi10Mg produced by selective laser melting (SLM). Two batches of samples were investigated by computed tomography (CT) and tested. A lower bound resistance curve was obtained introducing artificial defects. A fatigue crack growth simulation model based on the maximum defect size is proposed, able to estimate both the life and the scatter of the data in the fully-elastic region. Moreover, knowing the size and position of all the defects inside the samples, it was possible to foresee the defect at the origin of fatigue failure and to draw a hazard ranking based on the applied stress intensity factor.