Fatigue Induced Cavitation in Single-Phase Material

Abstract This paper presents calculations of the growth rates of grain boundary voids in single phase material. Raj's equations for the transient growth rate of cavities subjected to constant stress are extended to the case of cyclic loading. It is found that even under a fully reversed cyclic applied stress preexisting voids grow for an appreciable time. (However for growth to occur voids must first appear near the compressive maximum in a cycle.) When account is taken of the stress concentrations arising from the sliding of grains meeting in a serrated boundary, the transient growth is seen to be large and long-lived. Mean stress effects (including the influence of surface tension or gas pressure on the void surface) are greatly reduced by the presence of stress concentrations. It is found that in the course of cycling, large sharp stress peaks develop on the grain boundaries adjacent to the voids. The magnitude of these peaks increases with increasing frequency of cycling. This fact, together with rela...