Influence of deflected abrasive waterjet process on surface integrity and fretting fatigue properties of Ti-6Al-4V titanium alloy dovetails

Water jet peening holds great promise for enhancing the surface integrity and fatigue properties of materials. The deflected abrasive waterjet peening (DAWJP) process is well-suited for surface peening of metal components with confined geometries. Pressure is a key parameter that affects the surface strengthening of material. In this research, the dovetail slot of Ti-6Al-4V titanium alloy was strengthened using the DAWJP developed by our research group. The surface integrity of the dovetail slots before and after treatment under DAWJP processes at three pressures was systematically investigated, covering aspects such as surface roughness, residual stresses, microhardness, and microscopic morphology. The results indicated that under the DAWJP process with pressures of 50 MPa, 100 MPa, and 150 MPa, the depth of the plastic layer reached 18 μm, 23 μm, and 28 μm respectively. After DAWJP treatment, the surface roughness of the specimens was in 2 the range of 0.325 - 0.376 μm, and the microhardness was between 477.57 - 575.93 HV, showing an improvement compared to the original specimens. The maximum residual stresses at the three pressures occurred at depths of 17 μm, 20 μm, and 26 μm, with maximum values of - 642.41 MPa, - 692.62 MPa, and - 729.62 MPa respectively. At a load of 6 KN, the fretting fatigue life of the strengthened dovetail is 5.91 times and 2.15 times that of the unstrengthened one at room temperature and 400 °C respectively. The overall findings demonstrate that the employed DAWJP process can remarkably improve the fretting fatigue life of dovetail slots, with a particularly significant effect at room temperature.