INFLUENCE OF MICROSTRUCTURE FEATURES ON WEAR BEHAVIOUR OF Ti-64 TITANIUM ALLOY

Abstract

The mild to severe wear transition of Ti-6Al-4V titanium alloy was investigated. The correlation between microstructure and wear micro-mechanisms was also studied. Hot swaging at 900 °C was performed on the as-cast samples and thereafter two different solution treatments were applied on the swaged samples. The first treatment was applied at a temperature of 850 °C (below the β-transus temperature) for getting a bimodal structure (α+β), while the second treatment at 1050 °C was applied (above the β-transus) for getting lamellar structure (β). The solution treated lamellar structure resulted in ultimate strength of 1335 MPa and a hardness of 440 HV20 which are significantly superior to the bimodal structure. Wear behaviour of the studied Ti64 alloy was investigated at different sliding speeds in the range of 0.5 to 2.5 m/s with an interval of 0.5 m/s. The mild to severe wear transition was obtained at 1.5 m/s. The lowest wear rate was reported for the samples solution treated at 1050 °C due to their fine lamellae structure with high hardness. The worn surfaces of some selected samples were examined using SEM to determine the wear micro-mechanisms.