Pittsburg dispatch. [volume] (Pittsburg [Pa.]) 1880-1923, 1891-07-24
ARM0R PLATE TESTS.
The Nickel Steel of Carnegie, Phipps
& Co. Superior to Others.
FIVE SHOTS FIRED AT EACH MARK.
The Projectiles Fly in Many Fragments
When They Strike.
PROTECTIVE DECKS FOR NAVAL SHIPS

1
| WASHINGTON, July 23.-A comparative
armor test, to ascertain the relative qualities
of all steel plates and nickel steel plates for
use in arming the protective decks of naval
vessels, occurred at the naval ordnance
| proving ground at Indian Head this week.
The object Of the test was to obtain data to
be used in determining, whether the pro-
tective deck of armored cruiser No 2, the
New York, being built at the shipyard of
William Cramp & Sons, Philadelphia, should
be made of ordinary tough steel plates or of
nickel steel
Two pairs of plates were tested. Those
OF all steel were furnished by Cramp &
Sons, and were each N inches thick and
had $4,000 pounds tensile strength. The
nickel steel plates were from Carnegie,
Phipps & Co., of Pittsburg, and had 80, 900
and 1O2, 900 pounds tensile strength and II and
26 per cent elongation. Each pair of plates
was bolted to substantial live oak supports,
one plate being placed directly on top of
the other. This gave the all steel target a
thickness of 213 inches and the nickel steel
thickness of 8 inches, giving the nickel
steel q inch the advantage. The plates
were inclined at an angle of % degrees to
the line of fire, that being the angle at
which DETECTION decks are inclined.
Projectiles Break on the Steel Plates.
The gun used was a six-inch breech-
loading rifle, firing cast iron projectiles
weighted with sand to 100 pounds The
striking velocity was fixed at 1 ,515 feet per
second that being about the velocity at
which .six-inch shell fired with the service
charge would strike at range of 1000
yards. On the first day of the firing the all
steel plates were tested. The first shot was
fired at a spot 26 inches from the top of the
target and 10 inches from the right hand
edge.
1t struck the mark square and bent the
plates downward forming dish or depres-
sion ecliptical in form, with its apex three
inches below the normal surface of the
plates, and with the longest axis in the di-
rection of the line of fire. The surface of
the plate in this depression was smooth and
covered with copper from the rotating band
of the projectile. There were no cracks and
no bolts broken. The projectile broke up,
as did all the others fired during the trial,
and the fragments were DETECTED onward
through backstop of heavy timbers, laced
with a wrought iron plate, and were stopped
by pile of sand bags built up behind this.
Other Shots Have the Same Effect.
inches from the top and % inches from the
left edge, and was in effect an exact repeti-
tion of the first. The third shot was aimed
at the center of the plates, but an almost
imperceptible error in pointing the gun
was so magnifed by the inclination of the
plates that the shot &as too high and struck
Just between the two previous ones This
made row of three shots directly across
the upper part of the plate, and subjecting
it to a very severe test. The two previous
depressions were connected by this one,
which bent the plates down to inches be-
low the normal, and the center bolt, which
was just ahead of the point of impact, was
driven down through its hole. Both plates
were cracked from the center of their upper
edge through the bolt hole, and in the upper
plate the crack extended in a curve to the
rear of the first point of impact
The fourth shot struck at a point 81
inches from the bottom of the target and 10
inches from the right edge and was in effect
a repetition of the first two shots, as was
also the fifth and last shot, which struck 81
inches from the bottom and % inches from
the left edge. The target had stood the
trial admirably and though cracked by the
third shot, nothing had gone through it.
Nickel Plates Show Great Toughness
The nickel plates were then put in place
shot was at point 90 inches from the top
and 16 inches from the right edge, and it
made a depression but 40 inches below
the normal surface. The ridges found on
the surface of the plate by the mill scale
were slightly smoothed, and were polished
and FURNISHED with copper by the force of
the blow, but no other effect on the target
was visible. The second shot was at point
Sc inches from the top and II inches from
the left edge, and it made a depression
1 6-1O inches deep. The third shot struck
in the exact center of the plate, and was in
effect an exact repetition of the first.
The fourth shot struck % inches from the
top and 1S inches from the right edge and
made depression 1 9-10 inches below the
normal, as did also the fifth, which struck
80 inches from the bottom and IA inches
from the left edge. The greater apparent
depth of the depressions caused by the last
two shots was due to the fact that the
plates were made longer than was expected
and there was no room under the target
structure for putting nuts on the lower
bolts, which were merely driven in and al
lowed the bottom edge of the plates to curl.
1t is thought that the normal depression in
both these instances was about 1 4-10 inches.
The wonderful toughness of nickel steel was
again demonstrated by the test.