Improved Surface Integrity from Cryogenic Machining of Ti-6Al-7Nb Alloy for Biomedical Applications

Ti-6Al-7Nb alloy is emerging as an alternative biomedical material for replacing Ti-6Al-4 V alloy used in dental implants and femoral stem prosthesis applications. In cryogenic machining using liquid nitrogen, the surface integrity characteristics of Ti-6Al-7Nb alloy significantly improved compared to dry and flood-cooled machining. This study shows that surface roughness improved in cryogenic machining by 35% and 6.6% respectively, compared with dry and flood-cooled machining. Also, the hardness in the cryogenically-machined surface layer increased, by 33.6% and 14.7%, respectively, compared to dry and flood-cooled machining, with the formation of a severe plastic deformation (SPD) layer with less volume fraction of α-phase.