Enhancing the tribological properties of pure Ti by pinless friction surface stirring

Friction surface stirring (FSS) was employed to enhance the tribological properties of commercially pure Ti (CP-Ti). Applying FSS under the optimised process parameters (i.e. rotation and traverse speeds of 100 rpm and 8 mm/min, respectively) was found to increase the surface hardness of as-received CP-Ti from about 200–630 HV. The sliding wear resistance was therefore increased by 76, 76, and 85% under applied loads of 5, 10, and 20 N, respectively. The average friction coefficient (AFC) of CP-Ti also reduced considerably by the FSS. For instance, the AFC was reduced from 0.67 ± 0.07 and 1.04 ± 0.14 to about 0.33 ± 0.03 and 0.45 ± 0.04 at the applied loads of 5 and 20 N, respectively. The wear and friction mechanisms were also discussed.