Wear resistance and friction analysis of Ti6Al4V cylindrical ball-burnished specimens by vibration assistance

Abstract

Abstract The objective of the research is to analyze the impact of the ultrasonic vibration assistance on the wear resistance due to the topology enhancement caused on Ti6Al4V cylindrical samples after surface modification through a ball burnishing process. The process parameters considered for this study are the burnishing force, the number of passes and the addition of a 40 kHz ultrasonic assistance, which are thought to enhance the surface topology and increase the hardener effect in terms of depth. A complete screening design of 3 factors was performed, revealing that the number of passes and the vibration assistance are the most important parameters for minimizing the wear volume loss, being 170 N of burnishing force, 3 passes and the addition of the vibration assistance as the best combination found. However, no significant difference in the friction force was observed. The topology results show that there is a decrease in the average roughness from 1.50 to 0.45 µm with optimal burnishing conditions. It was also analyzed the microstructure originated after the turning, the conventional ball burnishing and the vibration-assisted ball burnishing, being the last optimal in terms of depth affectation to the microstructure. Therefore, these results confirm an improvement in terms of wear enhancement, friction reduction and topology results when vibration assistance is added to a conventional ball burnishing process.