On fatigue life variability in cast Al-10%Si-Mg alloys

Pore size and fatigue life data in Al-10%Si-0.3%Mg alloy castings reported by Casellas et al. [Mater. Sci. Eng. A 398 (2005) 171-179] were reanalyzed. Results showed that pore size data are modeled accurately by using the lognormal distribution. Consequently, a statistical distribution developed recently which combines the Gumbel distribution for size of largest defects and a crack propagation model has been applied to the fatigue life data. Analysis showed that the new statistical distribution provided respectable fits to the fatigue life data. Results also implied that fitting a curve to the upper tail of a pore size distribution was found to be inadequate for aluminum castings. Issues related to estimating the size of largest defects from pore size distributions by using statistical techniques are discussed in the paper.