Ti and its alloys (Ti6Al4V) have drawn a lot of interest from various industries because of their remarkable mechanical properties and biocompatibility. Despite having an excellent strength-to-weight ratio, their tribological characteristics are inferior. Laser surface modification can be a promising tool to improve the tribological properties of Ti and Ti6Al4V [1]. The tribological properties of Ti and Ti6Al4V depends on the presence and microstructural evolution of α and β phases. These α and β phases are tailored to meet the requirements of critical tribological applications in aerospace and biomedical sectors. Ti and Ti6Al4V undergo different microstructural transformation depending on the specific ambient environment. Atoms like oxygen or nitrogen occupy interstitial positions in the Ti and Ti6Al4V lattice during laser surface remelting and the rapid cooling leads to different microstructural evolutions [2-4]. Therefore, it becomes imperative to study the evolution of different microstructures and the effect of those microstructures on the tribological behavior of Ti and Ti6Al4V.

In the present study, the Ti and Ti6Al4V surfaces were remelted under different various ambient environments (Air, N2, Ar) using a nanosecond laser. After remelting, a smoothening operation was done throughcarried out using the laser in the presence of Ar to make the samples viable for tribotesting. The microstructural evolution of the Ti and Ti6Al4V substrates was studied at each step of the laser operation through FIB, SEM. Later on, unlubricated single trace experiments in ambient air as well as grease- lubricated tests under oscillating sliding conditions were carried out to understand the role of different microstructures on the tribological behavior of Ti and Ti6Al4V.