The influence of grain size variation on metal fatigue

The aim of the present study is to investigate the influence of the variation of metal grain sizes on fatigue lives. The grain structure is simulated from a Poisson-Voronoi model and the short crack growth model of Navarro and de los Rios is applied. The resulting fatigue life decreased with increasing component size, probably reflecting the fact that with increasing number of grains there is a larger probability of finding a large grain where the crack starts. The standard deviation of the logarithm of the lives was in the order of 0.2-0.4, i.e. the variation in grain size explains only part of the observed variance in real fatigue data.