Improving surface integrity and corrosion resistance of additive manufactured Ti6Al4V alloy by cryogenic machining

Additive manufacturing (AM) processes are rapidly growing, thanks to the chance they offer for the component customization in terms of both in-service performances and geometrical features. Nevertheless, AM products still need finishing operations to obtain suitable surface finish, which may introduce machinability issues on the basis of the different mechanical and microstructural characteristics AM metal alloys have compared with the wrought ones. This work presents the pivotal topic of surface integrity evaluation of electron beam melted (EBM) Ti6Al4V titanium alloy after finishing turning operations carried out under dry, flood, and cryogenic cooling conditions at different feed rates. For the sake of comparison, the same machining trials were conducted on the wrought alloy. The machining-induced effects were broadly studied in terms of microstructural and mechanical features, residual stress nature, surface topography, and defects. Moreover, the corrosion behavior of the machined surfaces in simulated physiological conditions was also tested, proving that the combination of the particular microstructure of the EBM Ti6Al4V alloy with cryogenic machining allowed for significant improvement of the corrosion performances.