Effect of groove surface texture on the fretting wear of Ti–6Al–4V alloy

Abstract Groove surface textures with different orientations and spacings were prepared on the Ti–6Al–4V alloy by using a laser. Fretting tests (rubbed with a Ti–6Al–4V ball) were conducted under different textures, and the coefficient of friction (COF) curves, system deformation and wear morphologies were analysed in detail. The groove orientations to the fretting direction affected the fretting wear behaviour through the following ways: (1) Fretting tests on different groove orientations resulted in different fretting loop shapes at the initial stage of fretting wear. (2) The COF curves of fretting test on perpendicular grooves and 45° grooves were similar. COF presented a sharp increase after approximately 1000 cycles under relatively low loads. The COF curves of fretting test on parallel grooves and untextured surface were similar. Only a small oscillation of COF was observed during the whole fretting tests. (3) When fretting was run in gross slip regime, the magnitude of system deformation was perpendicular grooves, no-texture samples, 45° grooves, and parallel grooves in order. The above results may have resulted from the influence of surface textures on the formation and development of wear debris. For the perpendicular grooves, high pressure was recorded in partial slip regime cracks, and peeling appeared on the convex platform of samples with the groove spacing of 80 μm, and this phenomenon promoted the formation of debris. Moreover, the perpendicular grooves prevented debris from spilling out of contact areas. For the parallel grooves, the filling mechanism of grooves was found, in which the material in the upper layer gradually squeezed the material in the lower layer toward the centre and bottom of the groove, and the parallel grooves accelerated debris from spilling out of contact areas. Therefore, groove surface textures may adjust the fretting regime of titanium alloys by changing the orientation and spacing, which could provide a new tribology design for fretting friction pairs.