This study investigates the effect of traverse speed on the surface characteristics of Ti6Al4V and Ti6Al7Nb alloys treated by ultrasonic pulsating water jet (PWJ). Surface topography, morphology, wettability, and surface free energy (SFE) were evaluated and compared with a commercial sandblasted Ti6Al7Nb femoral stem. The results showed that increasing traverse speed significantly reduced Sa and Sz for both alloys and changed the surface response from erosion to roughening and localized plastic deformation. Ti6Al7Nb generally exhibited slightly greater resistance to PWJ-induced erosion than Ti6Al4V. All PWJ-treated surfaces showed greater water wettability and higher SFE than the reference femoral stem. The polar and dispersive SFE components varied differently with traverse speed, indicating changes in the interfacial character of the treated surfaces. A traverse speed of v = 12 mm/s produced moderate micrometer-scale roughness together with favorable wettability and relatively high SFE, demonstrating the potential of PWJ for controlled modification of biomedical titanium surfaces.
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