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Titanium alloys are widely used in aviation, marine, automotive, offshore, and medical fields. However, their poor wear resistance reduces the safety and reliability of components during service. Few study has been previously conducted on the wear resistance enhancement of titanium alloys (including Ti–6Al–4V alloy) processed by mechanical cutting. High-speed ultrasonic vibration cutting (HUVC) is an effective approach for improving the machinability of titanium alloys. In this study, we attempted to utilize HUVC improving the wear resistance of titanium alloys. After conducting high-speed turning (cutting speed within the range of 200–300 m/min), the surface integrities (surface roughness, microstructure, in-depth micro-hardness, and residual stress) of conventional cutting (CC)- and HUVC-machined samples were characterized. Experimental results demonstrated that, compared with CC, HUVC achieved a thicker plastic deformation layer (greater than 46.93 μm), lower surface roughness, higher surface micro-hardness (greater than 433 HV0.05), and higher compressive residual stress (up to −840 MPa). Moreover, surface nanocrystallization and gradient nanostructured layer were observed in HUVC-machined Ti–6Al–4V samples. In addition, compared with CC, HUVC effectively further reduced the friction coefficient and worn volume loss (decreased by 20.98%–25.59%) and ultimately improved the wear resistance. The hardness has a higher influence on the wear resistance of the machined Ti–6Al–4V alloy than the other surface integrity factors. Therefore, the proposed mechanical cutting operation was confirmed to improve the wear resistance of titanium alloys.

In order to explore the cutting laws of difficult-to-machine material 27SiMn steel, an orthogonal method is employed in its cutting experiment by using carbide tool. The relationship between cutting process parameters (when cutting depth is 0.3～0.8 mm, feed rate is 0.08～0.2 mm/r, and rotating speed is 200～400 r/min) and three dimensional cutting forces is revealed, and the empirical formulas of three dimensional cutting forces are deduced by using the linear regression method. Experimental results show that cutting depth is the most influential factor in cutting force, followed by feed rate and cutting speed. Cutting force is positively correlated with cutting depth and feed rate, but when rotating speed is over 320 r/min, the cutting force decreases. The cutting force effect of empirical formula is verified through significance test.

The simulation of a complete manufacturing process to produce an aero engine case, including forging, rolling, and machining processes, is analyzed via finite element software. The deformation of the turning and drilling processes is quantitatively studied using the energy principles. Firstly, simulations of multi-stage forging of aero engine case and machining-induced residual stress are conducted and verified via the residual stresses test in order to provide the initial elastic strain energy condition prior to machining processes. The effects of blank forging-induced residual stress and machining-induced residual stress on the deformation of titanium alloys aero engine case are investigated. Secondly, a potential energy expression for the machining processes is developed. The predicted results of turning and drilling simulations indicate that there is an optimal process in which the deformation and potential energy decline rapidly compared with the other processes and finally, gradually stabilize at the end of the process.