Fatigue response of Udimet 720 following minimum damage wire electrical discharge machining

The paper presents experimental data for the fatigue behaviour of Udimet 720 nickel based superalloy following wire electrical discharge machining using minimum damage generator technology. Comparative data for flank milled samples are also given together with associated micrographs detailing workpiece crack initiation and subsurface integrity. Despite a marginally higher S–N response for the milled specimens compared to the wire machined samples subject to a finishing regime, statistical analysis suggested no significant difference in performance at the 5% level. In contrast, wire cut samples fatigue tested after only roughing, showed a markedly lower response commensurate with the greater surface roughness, the presence of surface microcracks and tensile residual stresses approaching 600 MPa.