Tool Wear and Surface Integrity of γ-TiAl Cryogenic Coolant Machining at Various Cutting Speed Levels

Abstract

High-speed machining of γ-TiAl alloy is a significant challenge due to high cutting temperatures. From the perspective of environmental protection and improving tool life, appropriate cooling strategies should be adopted. Compared with dry and conventional flood cooling conditions, the feasibility of machining γ-TiAl in cryogenic LN2 cooling conditions was discussed. The cutting force, tool wear and its mechanism, and surface roughness, as well as sub-surface morphology characteristics, were studied by combining macro and micro techniques. The results revealed that the wear morphology of the rake and flank face under the three cooling media shows different degrees. The crater wear of the rake face is expanded at high speeds and then progresses into more serve flaking and notching wear. The main wear pattern on the flank face is gradually transformed from adhesive wear to diffusion and oxidation wear at high speeds in dry machining. In the LN2 condition, the diffusion of workpiece elements and cutting-edge oxidation were restrained. The wear pattern is still mainly adhesive wear. In addition, cryogenic machining shows significant advantages in reducing cutting force, suppressing heat-affected zone, improving surface quality, and inhibiting micro-lamellar deformation.