Summary
Lifetime of aluminium castings subjected to dynamic loading is essentially influenced by microporosity. Within this research work fatigue tests were performed with specimens machined out of die casted plates. In all tested specimens crack initiation was observed at microporosity. Because of the different size of the crack initiating pore, the measuring points of fatigue tests show a wide scatter band. For characterisation of the influence of pore size on fatigue behaviour, the stress controlled approach by means of flaw size dependent S/N curves as well as the fracture mechanical approach was used. Therefore a possibility for enhancement of the Kitagawa-Takahashi-diagram to finite life fatigue strength is illustrated in this paper. The enlarged Kitagawa-Takahashi-diagram for finite life fatigue strength region based on fracture mechanical tests shows a good correlation with the results of fatigue testing.