抄録
The surface of metallic materials can be modified by introducing compressive residual stress thereby inhibiting crack initiation and/or growth. We have developed a new method, cavitation shotless peening (CSP), for improving the fatigue life of metallic materials. In this paper, beneficial residual stress were introduced by CSP. CSP is a new method of surface enhancement technique without using shots which differs from shot peening. CSP makes use of a high speed water jet with cavitation, herein referred to as cavitating jet, whose intensity and occurring region can be controlled by parameters such as upstream pressure and nozzle size. The cavitation impacts induced by the collapse of the cavitation bubbles produce compressive residual stress and work-harden the materials. The residual stress was measured using the X-ray diffraction method. To determine the improvement of fatigue strength of Duralumin (JIS A2017) using CSP, the specimen was tested using the rotating bending fatigue test while the surface analysis was performed by surface profile meter. Hardness changing with exposure times was determined using Microvickers. Comparisons of mechanical properties of non-peened and CSP specimens have been discussed. Experimental results showed that specimen treated by CSP in air had an increase of 65MPa (54%) in comparison to the non-peened specimen at fatigue limit.
