Effect of surface wear on fretting fatigue strength of shot-peened steels

Shot peening is one of the most effective techniques for improving fretting fatigue strength. Severe surface wear in the fretted region has often been found in practical large-size components. In the present study, the effectiveness of shot-peening under severe surface wear was investigated using as-peened specimens and specimens with shot-peening and subsequent grinding. The fretting fatigue strength was significantly improved by shot-peening. No degradation of fretting fatigue strength due to surface grinding up to 0.3 mm in depth was observed. The reason will be that the stress intensity factors due to compressive residual stress induced by shot-peening, which is the dominant factor for improving fatigue strength, are of more or less the same level regardless of surface grinding depth.