18. Short and Long Crack Growth of Aluminium Cast Alloys

Fatigue design of AlSi-alloy cast components is a challenging issue due to a great variety of the microstructure depending on the local cooling conditions, which majorly affects the local fatigue behaviour. Therefore, this paper contributes with an experimental evaluation of the short and long crack growth of aluminium cast alloys. At first, single edge notched bending (SENB) crack propagation tests show a distinctive transition of the crack resistance from the small to the long crack regime. At second, in situ fatigue experiments with an optical measurement of the surface crack length augment the crack growth data of the SENB-tests. In addition, the observations reveal that the local material condition, such as micro shrinkage pores or variation in local microstructure, affect the crack propagation as well as the crack path. Summarized, the presented work highlights that the short and long crack behaviour including the influence of microstructural properties needs to be considered thoroughly in order to properly assess the fatigue life of AlSi-alloy cast components.