Effect of microstructure on high-speed cutting modified anti-fatigue performance of Incoloy A286 and titanium alloy TC17

Anti-fatigue performance is vital for components used in aerospace industry, and cutting processes were widely considered to modify the workpiece anti-fatigue performance. However, most of the existing researches only associated the anti-fatigue performance to the cutting condition and surface integrity, without revealing the effect of material microstructure. In this work, the Incoloy A286 and titanium alloy TC17, two kinds of commonly used material in aerospace industry, were adopted as samples to reveal the influence mechanism of material microstructure on the high-speed cutting modified anti-fatigue performance. It was found that, due to the different microstructure, especially the grain structure and size, the effects of cutting process on the machined surface integrity and anti-fatigue performance of these two materials were different. For Incoloy A286, the large size and cubic structure increased the difficulty in deformation and breaking of grains, making the cutting parameters have limited effect on grain refinement. Hence, the fracture toughness of machined surfaces decreased on the whole with an increased feed rate and depth of cut, which reduced the fatigue life. For titanium alloy TC17, the small lath-shaped grains were easy to deform and break, resulting in the notably grain refinement of machined surfaces, which contributed to the prolonged fatigue life when the feed rate and depth of cut increased. All in all, the material microstructure may change the effect rule of cutting process on the machined workpiece anti-fatigue performance, and thus the cutting condition should be designed by considering the material microstructure.