Abstract: The surface of the TC11 titanium alloy is significantly strengthened through the ultrasonic tumbling process. The effect of ultrasonic tumbling process parameters on the microstructure and surface roughness of a titanium alloy using multiple techniques are investigated, including OM, white light interferometry, SEM, EDS, and XRD. The hardness, friction, and wear properties of the rolling surface are analyzed using a microhardness tester and a multifunctional friction-wear tester. The results indicate that the surface roughness of the titanium alloy decreases initially and then increases with an increase in rolling power, rolling times, static pressure, reduction, spindle speed, and feed rate. The lowest value is achieved with the following parameters: 660 W rolling power, 5 rolling times, static pressure of 0.20 MPa, reduction of 0.15 mm, spindle speed of 200 r·min^-1, and feed rate of 0.10 mm·r^-1. With an increase in power, the surface hardness of titanium alloy increases, which leads to a reduction in friction coefficient and wear loss. As the rolling times, static pressure, reduction, spindle speed, and feed rate increase, the surface hardness initially increases and then decreases. Meanwhile, the friction coefficient and wear loss tend to decrease initially and then increase. When the rolling power is set to 990 W, the rolling frequency is 5 times, the static pressure is 0.20 MPa, the reduction is 0.15 mm, the spindle speed is 200 r·min^-1, and the feed rate is 0.10 mm·r^-1, the hardness reaches its maximum value, while the friction coefficient and wear loss reach their minimum values. Response surface optimization was conducted to obtain the optimal process parameters, including a rolling power of 990 W, rolling frequency of 5 times, static pressure strength of 0.20 MPa, reduction of 0.15 mm, spindle speed of 198 r·min^-1, and feed rate of 0.10 mm·r^-1. Compared to the surface of the titanium alloy before rolling, the hardness increased by 36.4% from 337 HV to 461 HV, the surface roughness decreased by 89.9% from 1.88 μm to 0.19 μm, and the wear loss decreased by 83.3% from 0.60 mg to 0.10 mg.

Key words: ultrasonic rolling, titanium alloy, surface quality, friction coefficient, wear loss