Results of Surface Integrity and Fatigue Study of Wire-EDM Compared to Broaching and Grinding for Demanding Jet Engine Components Made of Inconel 718

Abstract

According to the jet engines fir tree slot production requirements, HCF bending test samples were produced by broaching andwire-EDM in Inconel 718. As an additional reference, a ground series has been produced. Initially, the surface integrities of the samples were checked by surface roughness measurements, SEM and rim zone views. All specimens meet the requirements of fir tree slot production. Following, the correlation between the surface integrity and HCF behavior was analyzed on a bending fatigue test bed. The reference series (grinding) possess the highest fatigue strength. The fatigue strength of the wire-EDMed and broached specimen are in the same magnitude. Therefore, from technological point of view wire-EDM provides an alternative to the established broaching process for the production of fir tree slots.