3.4. Ballistic testing
Ballistic performance of all the samples was measured using
the depth of penetration (DOP) method described elsewhere
(Jena et al., 2010). The DOP of all the samples are measured
and are plotted against tempering time, Fig. 7. It can be seen
that there is only a small variation in DOP in case of 7.62 AP
projectiles. However in case of 12.7 AP projectiles there is a
significant variation in DOP with tempering time. The DOP
increases beyond 2 h of tempering. The average DOP of the
2 h tempered sample against 12.7 mm AP projectile is measured
to be 14.2 mm, whereas it is 16.3 mm and 18.1 mm respectively
in 24 h and 48 h tempered samples.
Fig. 8 shows a close view of the front face of the samples
ballistically evaluated against 7.62 AP projectiles. The craters
are almost similar in appearance. However, small cracks are
observed inside of the crater wall in 24 h and 48 h tempered
samples. But no such cracks are observed in case 2 h tempered
samples.
Fig. 9 shows cut views of the craters in the target plates
tempered at 48 h and impacted by 7.62 AP as well 12.7 AP projectiles.
As can be seen the crater formed by 7.62 AP projectiles