Waterjet and abrasive waterjet surface treatment of titanium: a comparison of surface texture and residual stress

In this study, commercially pure titanium (cpTi) and a titanium alloy (Ti6Al4V) were subjected to waterjet (WJ) peening and abrasive waterjet (AWJ) peening surface treatments. The texture and in-plane biaxial residual stress of the treated surfaces were quantified using contact profilometry and X-ray diffraction, respectively. Regardless of the specific process conditions, the surface residual stresses resulting from WJ and AWJ peening of both materials were compressive. Residual stresses in the Ti6Al4V ranging −400≤σ≤−30 MPa, whereas stresses in the cpTi treated with the same conditions ranging −200≤σ≤−60 MPa. Residual stresses resulting from WJ peening increased with the WJ pressure whereas those resulting from AWJ peening decreased with an increase in both jet pressure and abrasive size. The surface roughness of the metals did not change appreciably with WJ treatment, but AWJ peening resulted in a significant increase in roughness. Therefore, AWJ peening may serve as a new method for introducing compressive residual stresses in engineering components that also require rough surfaces.