Wear mechanisms of WC/Co tools when machining high-strength titanium alloy TB6 (Ti-10V-2Fe-3Al)

Abstract

Titanium alloy TB6 is often used to produce key load carrying parts in the aviation and aerospace industries. The superior mechanical properties pose challenges to machining processes, bringing about such problems as rapid tool wear. In this paper, fine-grain WC/Co tools were utilized in dry turning of the TB6 alloy. The wear modes and wear mechanisms of the cutting tools at different cutting speeds were detailed. The analysis showed that the wear on the tool rake face was characterized as crater formation. The principal wear mode observed on the tool flank face appeared to be microchipping near the region of the cutting edge. The adhesion was more pronounced on the rake face than on the flank face. The clusters of WC particles were pulled out from the Co binder along the grain boundaries, which led to adhesive wear and left an intergranular fractured surface. The crater wear was a result of the elements of the cutting tool diffusing into the adhering material, which was carried away by the flowing chip, leading to a transgranular dissolution of the WC particles, and the worn surface was smooth. The chemical reaction possibly took place at the tool/adhering material interface, where the newly formed compounds were carried away by the flowing chip. The hard particles that adhered to the back surface of the titanium chip probably abrade the tool surface, causing abrasive wear.