VHCF of the 3D-Printed Aluminum Alloy AlSi10Mg

Abstract

The paper is focused on the very high cycle fatigue (VHCF) properties of aluminum alloys proceeded in two different technological procedures. The hot-rolled D16T alloy is compared with the selected laser melting (SLM) AlSi10Mg alloy. The fatigue tests were performed at a high frequency (20 kHz) in the laboratory air environment at room temperature. The experimental results showed a significant difference in fatigue strength between hot-rolled and SLM materials. The VHCF properties of AlSi10Mg were more than two times lower than those of D16T in spite of the comparable quasi-static tensile properties. The difference in fatigue properties was explained based on fractographic analysis of fracture surfaces. The morphology of the fracture pattern was qualitatively different. In the case of the hot-rolled alloy, the three clear zones of crack growth could be outlined. The main part of the pattern was covered by quasi-brittle facets that are typical for VHCF fractures in Al alloys. In the case of the SLM material, unregulated structures were found in the microstructure. In some local zones, numerous non-melted particles were observed on the fracture surface. The boundaries of certain layers also played an important role in the fracture. Large, separated surfaces were observed on the fracture pattern. It is important to note that these boundaries were not associated with the layer-by-layer building of the specimen. The distance between such features was significantly larger than the thickness of an individual layer.