Influence of Surface Integrity of 15-5PH on the Fatigue Life

The effect of surface integrity parameters on fatigue life has been investigated. Various surfaces have been manufactured with a controlled surface integrity in order to achieve fatigue test and to compare the influence of each parameters independently (residual stresses, surface roughness, and microstructure). The difficulty to reproduce the same surface integrity on each sample had been pointed out. It is necessary to characterize the surface of all the samples before testing and take it into account in the fatigue test procedure. Staircase tests have been carried out to determine the average fatigue strength at 2.106 cycles for each case of surface integrity. First results show that very good surface finish conditions combined with compressive residual stresses are beneficial.