Fatigue variability in Al-Si cast alloys

Fatigue fractures in Al-Si cast alloys are mainly triggered by existing pores, at which cracks may be nucleated and propagated under an applied stress. The variability of pore size produces a noticeable scatter in fatigue life results, which is associated with differences in the size of the fracture-controlling pore. Thus, pore size distribution accounts for the fatigue variability in cast alloys. In the present work, a methodology based on Weibull statistics, commonly applied to fatigue and fracture results of ceramic materials, is used to evaluate fatigue variability in sand-cast Al-Si alloys. The values obtained are in good agreement with experimental results. This indicates that fatigue variability in sand-cast Al-Si may be estimated from pore size distribution parameters and fatigue material properties. Moreover, such a method may be also applied to other metals whose fatigue behaviour is controlled by pores.