The effects of simultaneous laser nitriding and texturing on surface hardness and tribological properties of Ti6Al4V

The low hardness and poor tribological properties of titanium and its alloys significantly hinder their practical engineering applications, so surface nitriding or texturing is widely employed to improve the surface performances. However, previous studies mainly used the single method (surface nitriding or texturing), and simultaneous nitriding and texturing are rarely reported. Therefore, their combined effects on the surface mechanical and tribological properties are rarely investigated as well. In this study, by nanosecond pulse laser irradiation in nitrogen atmosphere, simultaneous nitriding and texturing of the Ti6Al4V surface were achieved. The effects of laser parameters including laser power, laser overlap rate, and number of scanning cycles, on the surface hardness and tribological properties of laser irradiated surfaces were comparatively studied. The experimental results showed that after simultaneous laser nitriding and texturing, the surface hardness of Ti6Al4V surface was increased by 50%~95%, and the coefficient of friction (COF) was reduced by 70%~80%. Furthermore, the laser processed surfaces obtained under various irradiation parameters presented quite different scratching characteristics, and the corresponding deformation mechanisms during scratching were analyzed. This study provides a simple and effective method by simultaneous laser nitriding and texturing for improving the surface properties of Ti6Al4V, which would be meaningful for its practical engineering applications.