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.