AN EXAMINATION OF ABRASIVE WATERJET PEENING WITH ELASTIC PRE-STRESS AND THE EFFECTS OF BOUNDARY CONDITIONS

Abrasive Waterjet Peening (AWJP) has emerged as a potentially viable method of surface treatment for components requiring compressive residual stress and a rough surface texture. In the present investigation the residual stress distributions resulting from AWJP of Ti6Al4V with load and displacement control flexure pre-stress were compared. An experimental evaluation was conducted to quantify the variations in the residual stress characteristics (magnitude and depth) as a function of boundary conditions over a pre-stress ranging from 0 to 75% of the material's yield strength. In addition, a finite element model for indentation-based surface treatments was developed to investigate the mechanisms contributing to the observed trends in experimental results. Overall, AWJP of the Ti6Al4V resulted in a surface residual stress ranging from approximately 800 to 1600 MPa. Load control pre-stress resulted in a larger surface residual stress (up to 50% greater) than that achieved under displacement control treatments. Although the maximum surface residual stress was obtained at the largest applied pre-stress, the difference between load and displacement control treatments decreased with pre-stress magnitude. Boundary conditions had limited influence on the depth of residual stress achieved, but were important to the depth of plasticized zone beneath the treated surface.