Research progress on formation mechanism of surface integrity in titanium alloy machining

Abstract

Titanium alloy is the main application material for the key components of aero-engine due to its excellent properties, such as light weight, high strength, high temperature resistance, and fatigue resistance. Because of its small elastic modulus, low thermal conductivity, and strong chemical affinity, it produces greater cutting force and higher cutting temperature in the machining process. Different thermal mechanical coupling effects can change the surface structure, composition, and mechanical properties of the material, resulting in different surface integrity state characteristics. This paper expounds the effects of process parameters, tool materials and properties, and lubrication methods on cutting force, cutting temperature, surface roughness and morphology, residual stress, microhardness, and microstructure based on the formation mechanism of surface integrity. It is pointed out that the existing researches mainly focus on the description of phenomena and laws. The research on the formation mechanism of surface integrity based on the thermal-mechanical coupling on the processing interface is lack, and the qualitative characterization system of surface integrity is not perfect. Therefore, the object of titanium alloy machining needs to be upgraded from test block to component, and the influence of the change of contact state of the processing interface caused by the time-varying machining trajectory on the surface integrity should be considered. Moreover, the quantitative evaluation of plastic deformation and grain characteristics is completed to accurately predict the gradient distribution of surface integrity. Taking fatigue performance as the goal, the surface integrity distribution meeting the service performance of components is deduced and designed, and then the processing conditions meeting the requirements are determined to realize the surface integrity processing.

Keywords

• titanium alloy
• cutting force
• cutting temperature
• residual stress
• microhardness
• microstructure