Improved oxygen diffusion and overall surface characteristics using combined laser surface texturing and heat treatment process of Ti6Al4V

Abstract

The combination of laser surface texturing and heat treatment process was barely investigated in the past, particularly for improved surface characteristics of Ti6Al4V. Hereby, the important role of laser scanning and post heat treatment in improving the oxygen diffusion depth and overall surface characteristics was analyzed. Polished Ti6Al4V surface was scanned using Nd:YAG nanosecond laser and analyzed for the oxygen pickup, phase change and hardness variation. The laser textured surface was heat treated to grow oxide coating over textured surface. In comparison with heat treated surface, the synergic effect of laser scanning and heat treatment improved the surface hardness by 15% and raised the TiO 2 rutile phase fraction from 0.36 to 0.73. The dual engineered Ti6Al4V surface was found to have superior HF1 quality adhesion strength along with the presence of low magnitude tensile residual stress. The increase in oxygen diffusion depth, diffusion coefficient and TiO 2 rutile phase fraction due to synergic effect of laser scanning and heat treatment were associated to the Ti 2 O 3 and C doping assisted anatase to rutile transformation mechanism. • Laser scanning is responsible for oxygen and carbon pickup and forms Ti2O3 phase at the Ti6Al4V surface. • Combination of LST and heat treatment improves rutile phase fraction, surface hardness and adhesion. • Oxygen diffusion depth and diffusion coefficient increase using laser texturing with heat treatment process. • Anatase to rutile transformation is prominent mechanism in laser textured with heat treated Ti6Al4V surface.