Local heat treatment with and without ultrasonic nanocrystal surface modification of Ti-6A1-4V alloy: Mechanical and tribological properties

This paper presents the results of a comparative study on the mechanical and tribological properties of Ti-6A1-4V alloy by local heat treatment (LHT) with (w/) and without (w/o) ultrasonic nanocrystal surface modification (UNSM) technique at high temperatures of 400, 600 and 800 degrees C. The objective of this study is to further improve the mechanical and tribological properties of Ti-6A1-4V alloy by the combination of LHT + UNSM treatment. The hardness measurement results revealed that the hardness of Ti-6A1-4V alloy after LHT was increased with increasing the temperature, but it was further increased by the combination of LHT + UNSM treatment. It was also found that the wear resistance was increased in the same temperature order, where the highest temperature of 800 degrees C exhibited the highest wear resistance. However, even though the hardness was increased after LHT, but no significant difference in wear resistance was found between the untreated and heat treated (400 degrees C) Ti-6A1-4V alloy. The wear mechanisms of the samples treated at various temperatures were also discussed based on the obtained SEM images of the wear tracks. The development of the combination of LHT + UNSM treatment was successfully demonstrated the possibility of being applied to Ti-6A1-4V alloy to achieve a significant high hardness. (C) 2017 Elsevier B.V. All rights reserved.