Effect of load on the fretting tribocorrosion behavior of Ti6Al4V in seawater

Ti6Al4V alloy used as fasteners and heat exchangers in seawater suffers from the combined damage of corrosion and fretting wear. Fretting tribocorrosion of Ti6Al4V alloy was investigated in seawater at different applied loads. The results demonstrated that wear volume increased from 1.35 × 10􀀀 2 mm3 at 10 N to 2.05 × 10􀀀 2 mm3 at 50 N, while wear rate decreased from 1.87 × 10􀀀 5 mm3/N⋅m at 10 N to 6.27 × 10􀀀 6 mm3/N⋅m at 50 N. Significantly, the account of mechanical wear, W0, increases from 21.32 % at 10 N to 82.14 % at 50 N, and the synergism component decreases from 78.6 % to 17.81 %, predominantly the reduction in corrosion accelerates wear from 75.26 % to 13.59 % due to the inhibition effect of mechanical wear on pitting corrosion. Therefore, at
low load, fretting tribocorrosion was dominated by corrosion-accelerated wear, whereas under high-load conditions, mechanical wear becomes the primary damage mechanism and exerts an inhibitory effect on the further progression of pitting corrosion. The wear mechanism was characterized by plastic deformation, adhesive wear, abrasive wear, and delamination wear. A typical graded subsurface microstructure formed with increasing applied load, exhibiting progressively thickened individual layers as the load escalated.