Understanding fatigue crack propagation pathways in Additively Manufactured AlSi10Mg

Abstract

Alloys produced through additive manufacturing (AM) offer substantial advantages, particularly in controlling material utilisation and precisely manipulating processing parameters, resulting in finely tuned material properties. However, the grain structure of AM material is typically complex, influenced by factors such as solidification dynamics, processing parameters, thermal gradients, and residual stress. Fatigue analysis shows considerable scatter due to entrained defects which limits their use as structural components. In this study, fatigue-failed samples from selective laser melted (SLM) AlSi10Mg alloy, oriented horizontal and vertical to the build direction were analysed to understand crack propagation paths. Here X-ray Computed Tomography (CT) was used to examine internal porosity from which fatigue cracks initiate, complemented by electron backscattered diffraction (EBSD) mapping. This enabled us to recognize the crucial role of the complex grain microstructure in controlling fatigue crack propagation.