Abstract
γ-TiAl, gamma titanium aluminide, is a unique metal matrix composite, the structure of which provides exceptional properties that include low density, high yield strength, high stiffness, high specific stiffness, etc. Consequently, γ-TiAl alloys are long being considered for substituting several superalloys for various applications in the fields of automotive, aerospace and biomedical industries. However, γ-TiAl is well-known as very difficult to machine, which has hindered the widespread application of γ-TiAl. In this paper, a central composite design (CCD) of experiments is adopted to investigate various turning process responses with hexagonal shape inserts. Results show that, among three turning factors, the depth of cut factor has the greatest impact on cutting force responses, while the feed rate factor has the most dominating effect on specific cutting energy and surface finish. Quadratic equations are developed, and the corresponding two-dimensional and three-dimensional plots are established. By means of regression analysis and response surface methodology (RSM), a series of optimal turning parameters is obtained, which renders the minimum machining energy, leading to increased tool life and improved machinability. Furthermore, it is feasible to achieve an industry-accepted surface finish. The results of this work cover a machinability investigation of a gamma titanium aluminide that can find application in automobile and aerospace industries for machining of high-temperature resistance parts.
