Synergistic surface engineering of PBF-EB/M Ti–6Al–2Sn–4Zr–2Mo: linking support-fingerprint morphology to high-temperature tribological behavior

This study investigated the effects of two industrialized post-surface treatments, grinding, and grinding-tumble finishing, on the tribological behaviour of Ti–6Al–2Sn–4Zr–2Mo (Ti6242) samples produced via Powder Bed Fusion-Electron Beam/Metal (PBF-EB/M), focusing on surfaces that retain the characteristic fingerprint of support structures. By employing a combination of grinding and tumble finishing, this research aimed to mitigate the negative effects of surface irregularities, enhance wear resistance, reduce friction, and, consequently, make these components suitable for demanding applications such as aerospace engine and turbine components, where high temperatures and frictional stresses are critical. Friction tests were conducted from room temperature to 450 °C, complemented by nanoindentation, surface roughness, and microhardness analyses. The combination of grinding and tumble finishing resulted in a ~ 10% increase in hardness and improved the hardness-to-elastic modulus ratio compared to grinding alone. Interestingly, although the hybrid-treated surfaces exhibited slightly higher surface roughness (Ra) than the ground samples, they demonstrated superior tribological performance at room temperature. This hybrid treatment also reduced the friction coefficient at 450 °C, which may be attributed to the formation of titanium oxide, which enhances lubrication. The study demonstrated the effectiveness of the combined treatments in mitigating the negative impact of support structure features on the tribological performance of the final components.