Corrosion Behavior of Shot-Peened Ti6Al4V Alloy Produced via Pressure-Assisted Sintering

Abstract

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.

Surface properties of micro surface patterned Cp-Ti alloy via electrical discharge machining

“…It is frequently employed in dental implants due to its desirable biological characteristics, low Young's modulus, and adequate strength [6]. Nevertheless, its wear rate and coefficient of friction (CoF) are comparatively weak, which limits its use to situations in which sliding, fretting, and rolling contact are unavoidable [5][6][7][8][9].…”

“…In biological applications, patterned surfaces enhance cell adhesion and proliferation, which is crucial for tissue engineering [17]. Moreover, patterned features may enhance the corrosion resistance of titanium alloys by modifying the surface chemistry [9,18]. As micro-bearings, well-designed surface patterns may boost the dynamic pressure between friction pairs, trap debris produced during the friction process, and store lubricant [19].…”