Tribological behavior of nanosecond-laser surface textured Ti6Al4V

Titanium alloys are used due to their high specific strength and remarkable corrosion resistance. Their wear resistance however is poor, which in this paper is counteracted by laser surface texturing. Linear textures were created by the use of a nanosecond-pulsed laser, accompanied by melt bulges of resolidified material on the sides. Packing density, finishing procedure and atmosphere during laser texturing were varied between the experiments. Melt bulges lasered in air turned out to be tribologically beneficial in grease-lubricated sliding contact, reducing wear volume on Ti6Al4V significantly by up to a factor of 160, if a packing density of 5% or more was chosen. Further investigations of melt bulges with energy dispersive X-ray spectroscopy (EDX) and scanning transmission electron microscopy (STEM) revealed an increased content in interstitial oxygen and nitrogen and a purely martensitic alpha'-phase microstructure. Critical limitation of plastic deformation and a saturation of electronic bonds of the titanium atoms by interstitial elements is thought to be responsible for the reduction in adhesive tendency and therefore the pronounced decrease in wear.