Influence of thermal mechanical coupling on surface integrity in disc milling grooving of titanium alloy

Disc milling strategy has been applied in grooving for decades for its capacity to provide huge milling force on the difficult-to-cut material. The processing efficiency of machined components thus can be tremendously improved with the application of disc milling. However, the fundamental research of the mechanisms of disc milling on cutting metal materials, especially on titanium alloys, is lacking in the literature. In this study, the milling force and temperature were inspected in disc milling grooving experiment, and the effect of thermal-mechanical coupling on surface integrity of titanium alloy, including surface roughness, surface topography, surface and subsurface residual stress, microstructure, and microhardness, was analyzed. The results showed that a better surface quality can be obtained at the center of the surfaces compared to the marginal regions on the same machined surface. Residual compressive stress was generated on the machined surface and subsurface and gradually reduced to zero with an increase in depth. The microstructure of lattice tensile deformation was emerged along feed direction, while the phase transition was not produced. A hardened layer was found on the machined surface and subsurface, mostly causing by the mechanical loads and oxidation reaction.