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This work aimed to investigate the effect of the burnishing surface treatment on the tribocorrosion resistance related to Ti6Al4V specimens, in the framework of the head-neck tribo-pair characterising a total hip replacement. The experimental procedure carried out started by choosing the specimens referred to different burnishing conditions together with specimens not treated or treated only with the turning process. Then, tribocorrosion experiments with fixed load and two frequencies were conducted through a reciprocating tribometer equipped with a potentiostat able to measure the electrochemical corrosion potential and current associated to the synergistic wear phenomenon analysed together with the coefficient of friction. Furthermore, optical topographical acquisitions were performed before and after the experiments. The results showed that the non-burnished specimens exhibited unexpected oscillations of the coefficient of friction approximately in the middle of the rubbing phase and the same happens for the cell potential; the wear volume was measured after the tribocorrosion test. This allowed to estimate the wear factor related to all the analysed configurations, showing a greater mean value in correspondence of greater sliding frequencies in the non-burnished cases, while the opposite happens in the burnished cases. Finally, the burnished sample at the lower burnishing force resulted to have the noblest corrosion potential, while the non-burnished samples exhibited the lowest corrosion current density.

Finite Element analysis can be a valid alternative to expensive, time consuming and destructive experimental tests. However, the reliability of a numerical model needs to be properly verified by a robust calibration and validation method, able to demonstrate the effectiveness of the proposed technique. A topic of considerable scientific interest is the estimation of residual stresses in the engineering field, since the available experimental techniques present a limited range of applications, because of the complexity of measurement as well as problems associated with measurement accuracy and applicability to a broad range of materials. This paper presents the development of a numerical model able to calculate residual stresses due to the effects of machining, using the nanoindentation method. Numerical simulations of indentation tests on stressed and stress-free samples were carried out, calibrated and validated using experiments. Results concerning the presence of residual stresses are presented with a good agreement with the experimental evidences.