Effects of Shot-Peening on the Fatigue Properties of 300M Steel

摘要

Effects of shot peening on the residual stresses and fatigue properties of 300M steel were studied. The fatigue strength was enhanced by 90 MPa and the fatigue life was improved approximately by 800 percent with the shot peening at 24 amp. of impeller current for 2 min. Excessive shot peening caused surface defects and reduced the improvement of fatigue properties. The fatigue crack initiation site was found to move to subsurface, mainly near non-metallic inclusions, with the increase of shot peening intensity and residual stress, but the defects on the surface was dominant crack initiation site in the excessively shot-peened specimen. The mechanism of improvement in fatigue properties in case of the subsurface fatigue crack initiation was discussed.