High cycle fatigue performance of AlSi10mg alloy produced by selective laser melting

Selective laser melting (SLM), which is an additive manufacturing (AM) technology, has been widely used in industrial fields. The inherent defects resulting from the SLM process are inevitable. The effect of building directions on the static mechanical properties has been observed. However, certain critical functional components are under cyclic loads and extreme service conditions. The effect of inherent defects and building directions on the high cycle fatigue (HCF) performance of SLM alloys is not very clear. More testing data should be provided. Therefore, in the present work, the rotation bending fatigue (RBF) tests of SLM AlSi10Mg bar samples that included three building directions are carried out. These results indicate that most fatigue cracks initiated from the unmelted defects of the sample surfaces (or subsurface). The SLM building directions have an obvious impact on the AlSi10Mg alloy fatigue properties. The 0 degrees samples exhibit a higher fatigue limit value than the 45 degrees and 90 degrees samples. Moreover, the crack propagation mechanism is revealed by fracture analysis. The negative effect of multiple-crack initiation on the RBF specimen fatigue lives under low cyclic loads is explained in detail. Finally, the evaluation method for the fracture toughness (K-IC) by the fracture surfaces of the RBF samples is provided.