Laser surface melting of Ti–6Al–4V under the influence of ultrasonic vibrations

Abstract

Ti-alloys are becoming increasingly important in several manufacturing sectors due to their high strength-to-weight ratio and excellent corrosion resistance. However, surface modification of the Ti-alloys is often required to improve surface hardness and wear resistance. In this paper, laser surface melting (LSM) of Ti–6Al–4V alloy under the influence of ultrasonic vibrations (20kHz) is investigated. The development of microstructure and microhardness in the resolidified region with and without the application of simultaneous ultrasonic vibrations is discussed. It has been observed that the application of ultrasonic vibrations entirely eliminated the large columnar grains from the resolidified region and refined the microstructure, resulting in about two-fold increase in the surface microhardness. The microstructural refinement with the application of ultrasonic vibrations during LSM seems to be primarily due to enhanced fluid flow and cavitation in the melt.