SUMMARY
The subject tests were conducted at 200, 300, and 400
obliquities with 3" M62 capped projectiles at e/d values of 1.01
(370 STS), and 1.39 (410 Class B). The plates were heat treated
over a range of tensile strength from 110,000 psi to 225,000 psi.
Owing to wide variations in type of projectile failure and
to plate non-uniformity, no general statement can be made
regarding the optimum hardness of the subject 3" armor under
the test conditions described, and no consistent effects on
ballistic limits of variations in obliquity or tensile strength
were noted. However, the optimum hardness of the 4" ermor appears
to be in the neighborhood of 150,000 psi for the 200 and 300
obliquity tests.
The variations in ballistic limits are qualitatively analysed from the standpoint of the energy requirements for
plate and projectile failures which, in turn, were observed to
depend on the plate tensile strength.