Introduction of compressive residual stress into stainless steel by employing a cavitating jet in air

In order to eliminate stress corrosion cracking, a method of introduction of compressive residual stress using cavitation impacts was proposed, without use of shots. The cavitation impacts were successfully produced by a cavitating jet in air, without the requirement of a water-filled chamber. The injection condition of the jet was optimized and the introduction of compressive residual stress into stainless steel was demonstrated using the jet. The maximum compressive residual stress introduced by the optimized jet was 500 MPa on the surface, while the thickness of the modified layer was up to 400 μm. A method for estimation of the introduced compressive residual stress by the jet as a function of processing time was proposed, considering the stochastic phenomena of the cavitation impacts. Both the intense impact at 0.2 Hz and relatively weak impact at 4.5 Hz affect the introduction of compressive residual stress. The value of the residual stress and the thickness of the modified layer can be estimated by the proposed experimental equation.