Cavitation shotless peening for improvement of fatigue strength of carbonized steel

Cavitation shotless peening (CSP) is a surface enhancement technique which makes use of cavitation impact to induce compressive residual stress on the metallic materials, thereby increasing the fatigue life of components. The technique is similar to shot peening except that shots are not used and that is why we refer to it as shotless peening. In case of CSP a submerged high-speed water jet with cavitation, i.e. a cavitating jet is used. To explore the potentials of CSP as a means of improving fatigue strength, carbonized chrome-molybdenum alloy steel (JIS SCM415) has been analyzed in the non-peened, shot-peened and CSP conditions with respect to processing times, residual stress and cyclic-stress curves. The residual stress was measured by an X-ray diffraction method. Experimental results confirmed that the rotating beam fatigue strength of a CSP specimen was stronger than non-peened and shot-peened specimens by 79 and 27 MPa, respectively.