Current demands of higher damage-tolerance in the Aerospace industry resulted in
resurging interest in β, or near β, titanium alloys. The combination of attractive
properties of this class of alloys also led to the consideration of beta alloys for
castings. Such alloys, however, are more difficult to cut than α-β titanium alloys due to
their limited ability to work harden and the effect of β-stabilizers on ductility.
These factors affect failure modes and active wear mechanisms of cutting inserts. This
paper investigates some of the wear modes exhibited by WC-Co inserts when end milling the
α
near-β
alloy Ti-x.
In addition to being of near-β composition, this alloy is characterized by a fine
sized microstructure (range of 1−5 μm). The study focuses on SEM and EDS observations of
the wear patterns exhibited by two groups of inserts. The first is uncoated WC-Co, whereas
the second is coated with multi layers of TiAlN. The results of this post-mortem study are
compared to wear patterns, observed under identical conditions, while milling the
α-β alloy Ti6Al4V. Results show that inserts used in
machining the Ti-x alloy exhibit wear modes that contrast those
exhibited when machining Ti64. The paper discusses factors leading to such occurrences and
studies the influence of the alloy microstructure on tool effectiveness and failure modes.