Influence of pores on the lifetime of die cast aluminium alloys studied by fracture mechanics and X-ray computed tomography

Abstract

Pores and other defects play a crucial role in aluminium die cast alloys. They critically affect the fatigue properties and lifespan of components. The application of fracture mechanics methods is a cornerstone in the calculation of high cycle fatigue properties of such components. In recent research failure behaviour and internal structure of defects are analysed and predicted based on X-ray computed tomography scans (CT) and machine vision integrated into the simulation models. Here, we present the analysis of defects of the die cast aluminium alloy EN-AC46200. In the first step, we use CT scans to analyse pores and defect structures. Afterwards, the CT scans are evaluated for pores and defects using modern 3d image analysis software. Additionally, the samples are tested by high cycle fatigue until failure. To determine the stress intensity, the pore analysis is combined with the help of machine vision. Furthermore, a novel clustering method based on 3d volume data is proposed to predict critical regions of the samples. We show that by this approach we can augment the fracture mechanics of the defects and identify critical pores in combination with stress hot spots in the aluminium die cast alloy.