Transition between mild and severe wear in titanium alloys

The mild to severe wear transition of two titanium alloys, Ti-10V-2Fe-3Al (a near-β titanium alloy) and Ti-6Al-4V (an α+β titanium alloy) was investigated and the correlation between the microstructure and wear micromechanisms was studied. Mild wear was dominated by oxidation via the formation and spallation of mechanically mixed layers (MMLs). The near-β alloy exhibited lower wear compared with α+β alloy in the mild wear region due to more stable MMLs as evidenced by 16% higher thickness of layer. Severe wear was characterized by strain localization and subsurface crack growth. Ti-6Al-4V showed lower transition load and lower resistance to unstable plastic deformation. However, Ti-10V-2Fe-3Al exhibited higher critical shear strain for subsurface crack initiation.