This carbonizing process is very
similar to the cementation process of producing steel, and by it the
face of the plate is made high in carbon and very hard.
The system invented by Sir Joseph Whitworth, of Manchester, England,
consists in what might be called scale armor. A section of a sample of
the armor represents four plates. The outer layer, one inch thick, is
composed of steel of a tensile strength of 80 tons per square inch;
the second layer, one inch thick, of steel whose tensile strength is
40 tons per square inch; the third and fourth layers, each one-half
inch thickness, of mild steel. The outer layer is in small squares of
about ten inches on a side, and is fastened to the second layer by
bolts at the corners and one in the middle of each square. The surface
is flush. (See Fig. 9.) The end sought by the above system is to break
up the shot by the hard steel face and to restrict any starring or
cracking of the metal to the limit of the squares or scales struck.
The bolts are of high carbon and are extremely hard steel.
[Illustration: Fig. 9.]
Armor plates must often be bent or curved to single or double
curvature and sometimes to a warped surface to fit the form of the
ship. There are several methods of bending plates. One method employs
a cast iron slab of the required form, which is placed on the piston
of a hydraulic press.
Pages:
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72