Fatigue crack initiation in a notched single-crystal superalloy component

In this paper, the fatigue crack initiation in notched single-crystal test specimens of material MD2 is investigated and analysed. A critical plane approach is adopted, in which the total strain ranges on the discrete slip planes are evaluated. Furthermore, a Coffin-Manson type of expression is used to describe the number of cycles to fatigue crack initiation. This relation is determined from a set of smooth test specimens loaded uniaxially in the [001], [011] and [ 11] directions at 500oC with R = 1. The numerical procedure is then applied to a series of experiments, in which notched single-crystal test specimens were exposed to uniaxial cyclic loading in the [001] direction at 500C with R = 0.