The present study reveals for the first time the dry sliding wear behavior of a powder metallurgical pure titanium alloy (Cp-Ti) modified by shot peening. Cp-Ti samples were manufactured via powder metallurgy, and then their surface and subsurface features were modified using a custom-made, fully automated shot-peening system. The texture isotropy rate and the highest orientation angle of the shot-peened samples were 71.5% and 36°, respectively. The Abbott curves of the shot-peened surfaces revealed that the most common areal roughness value was 5.177 μm, with a frequency of 8.1%. Shot-peened surfaces exhibited an ~20% lower wear rate than unpeened surfaces under dry sliding wear, whereas the coefficient of friction was the same for both surfaces. Micro-ploughing, micro-cutting, oxidation, and three-body abrasion wear mechanisms were observed on the shot-peened and unpeened surfaces. High resolution 3D surface topographies of worn unpeened and shot-peened surfaces revealed micro-scratches and inhomogeneities along wear tracks, which are indicative of three-body abrasion mechanisms during contact. In addition, vertical and horizontal microcracks were visible just beneath the wear track, suggesting a clear indication of plastic deformation during contact. The cross-sectional hardness maps of shot-peened samples revealed the formation of a work-hardened surface layer with shot peening, which improved the wear resistance. These findings support that shot peening can be a useful tool to modify the surface and tribological properties of powder metallurgical Cp-Ti alloys.

For the first time, the present study investigates the corrosion, surface, and subsurface properties of a shot-peened Ti6Al4V powder metallurgical alloy produced via pressure-assisted sintering. Shot peening yielded a fine-grained microstructure beneath the surface down to 100 microns, showing that it caused severe plastic deformation. XRD analysis revealed that the sizes of the crystallites in unpeened and shot-peened Ti6Al4V alloy samples were 48.59 nm and 27.26 nm, respectively, indicating a substantial reduction in crystallite size with shot peening. Cross-sectional hardness maps of shot-peened samples showed a work-hardened surface layer, indicating a ~17% increase in near-surface hardness relative to unpeened samples. Three-dimensional surface topographies showed that shot peening yielded uniform peaks and valleys, with a maximum peak height of 4.83 μm and depth of 6.56 μm. With shot peening, the corrosion potential shifted from −0.386 V to −0.175 V, showing that the passive layer developed faster and was more stable than the unpeened sample, improving corrosion resistance. As determined via XRD analysis, the increased grain refinement (i.e., the number of grain boundaries) and the subsequent accumulation of TiO₂ and Al₅Ti₃V₂ compounds through shot peening also suggested the effective formation of a protective passive layer. As demonstrated via electrochemical impedance spectroscopy, the formation of this passive film improved the corrosion resistance of the alloy. The findings will likely advance surface engineering and corrosion research, enabling safer and more productive shot peening in corrosion-critical applications.