SEMimages taken fromthe flankworn surfaces of the cutting inserts
after cutting tests are shown in Figs. 4–9. It can be seen that the wear
band of sample A is uniform with light abrasive tracks (Fig. 4(b)) on
worn surface. It indicates that the dominant wearmechanism is mainly
abrasive wear, when cutting gray cast iron in these conditions. In addition,
the EDS analysis of point 1 on the worn surface (Fig. 4(c)) reveals
that a small amount of adhered-particles are found on theworn surface,
which are transformed from the workpiece during the turning test.
Fig. 5 shows the worn surface of sample B in the end at the speed of 300 m/min. It can be seen that the sample B has a rough worn surface
after the cutting process. There is a large amount of adhered materials
from workpiece on the worn surface. It is suggested that the main
wear mechanism is adhesive wear which frequently occurs because of
shearing contact points between cutting tool and workpiece, and adhesion
or cold welding which transfers materials between wearing surfaces
caused by high pressure and temperature [5]. Figs. 6 and 7
describe the worn surface of the both cutting inserts in the end of the
test at the speed of 450 m/min, respectively. It can be seen that the
worn surface of sample B is relatively smooth while that of sample A
is rather rough in Figs. 6a and 7a. Obviously, the dominant wear mechanisms
are adhesive and abrasive wear for the both cutting inserts.
However, the difference is that the abrasivewear of sample B ismore severe
than that of sample A, and the adhesive wear in sample A is worse
than that of sample B. Compared with the situations of former speed,
the adhesive and abrasive wear of the cutting inserts are both worse
than that of former situations. As the cutting speed increased, it can be
clearly seen that the dominantwear mechanismof sample A is adhesive
wear in Fig. 8.However, for the sample B, they are adhesive and abrasive
wear in Fig. 9. In addition, the abrasive wear of sample B is very severe,
with many deep grooves that can be seen on theworn surface. A severe
abrasion would deteriorate the wear resistance of cutting inserts.