Evening star. [volume] (Washington, D.C.) 1854-1972, 1894-05-21
ARMOR PLATE FAILURE
Eighteen-Inch Steel Crumbled by Twelve
Inch Guns.
Discussing the Reasons-The Plate
Was Defective, With an Internal
Fracture-Another Test.

the Indian Head Proving grounds Satur-
day afternoon was a disappointment to the
experts because OF the Effectiveness OF the
plate. Such as IL was, II clearly demon
strated the superiority of a 12-inch gun and
Carpenter projectile over a specimen Is
inch plate from the works of the Bethle-
hem Steel Company. The unexpected weak
ness shown by the plate is accepted by
some as an indication that the Harvey pro-
cess Of surface carbonization cannot be
successfully employed in tine case of armor
of such thickness. If the plate badly de-
molished in the ballistic test of Saturday 10
fair representative of the forward belt
armor OF the battleship Indiana. il means
loss of nearly 100000 90 the manufac-
turers. as In that case the government viii
refuse to accept it, below the contract
requirements.
The plate submitted to the test weighed
30 Ia tons and cost about $1,000 In shane
it was an irregular oblong 10 feet long by
1-2 feet high. Is inches thick above with the
lower edge CI2 inches beveled off to a min
imum thickness Of inches. 1t was nickel
steel, forged by hydraulic press and Har-
yeyized.
A i3-inch rife, the largest In naval use.
was to be fired against this. but the plate
was found TO be too narrow to warrant
TINS severe test, so the Finch gun which
will hereafter be the maximum in our ord
nance construction, was leveled at the plate.
Instant about 400 feet The proiectile a
Carpenter armor-piercer weighing 60
pounds and driven by 269 IA pounds of Du-
points brown prismatic powder, few across
tne space with the velocity Of I,465 feet per
second, and struck the plate about a foot
TO the right of the center
Inc effects on the plate of this shot were
startling; The point of the shell just pen
etrated the plate 1t rebounded thirty feet
and was picked up slightly set up. Ths
point OF impact was a large Jagged hole
showing that the shell had plowed its way
INTO the target with fearful force Three
cracks divided the plate into as many dis
tihct parts. One crack, nearly twelve
inches in width. extended from the point OF
impact to the top OF the plate. another TO
the IeIt-hand side and the third 10 the bot
tom. All the cracks were large enough IN
their widest part to admit a mans head.
ana dwindled on into division OF two or
three inches in extent.
The cracks were through and through.
they ran TO the edges and the lacking was
exposed; although the plate had thrown
back the proJectile, il had failed to comply
with the specifications.
An examination of the long crack. ex-
tending toward the top end of the plate
showed a broad band of darkened metal ex-
tending Tor nearly one-haif the length OF the
plate to within two inches TO one-half inch
Of the front and back edges.
III was simply an immense internal crack
formed in water hardening, which had rot
direction
and SO had been concealed from sight
Signal Failure.
Further experiments seemed to be need
less. but the contract conditions requiring
it. another shot was fired at fragments OF
plate on the right about seven feet broad
that remained uninjured. This time the
gunner put 419 $40 pounds of powder in the
gun. and the projectile. another twelve-inch
Carnanfpr WAS civ al
sent at the maximum velocity. 926 feet
per second. Again the plate was rent in
twain. splitting widely across. but the shot
did not escape, for, while it forced its point
through the plate and about eight inches
through the oak backing. IL was twisted in
several pieces. the point remaining in the
hole and the remainder lying in fragments
outside the plate. This was the end Of the
test, and the plate failed sgnally.
The results naturally provoked an ex-
change OF expert views. Every one remark-
Cd mat the outcome was unexpected. but
there was no such unanimity Of opinion re-
gaioing the lesson which the test taught
Some of the steel men were Of the opinion
that the Harvey process could not be safely
applied TO plates of this thickness w III
Jacques of the Bethlehem iron works an
authority on ordnance matters did NOT
share this view. He said that at the foun-
dry the plate was noticed TO have under
| gone influences while cooling. and IL was
now realized that the contractors had sent
an inefficient plate. although there were no
indications of the weakness on the surface
Capt. Sampson said there would be no
change in the application of the Harvey
II eatment. because of the damage of the
/ Bethlehem plate. Another plate from the
same lot might sustain all that previous
/ tests have gained i'm reputation for the Har-
| vey process Of surface hardening. Most Of
| the experts believe IL would. Even this in
! efficient plate kept out the shell. The
Bethlehem people will probably send another
plate TO Indian Head.
The bethlehem company will have an op-
/ portunity TO submit another ls-inch plate to
/ test before the entire group OF tweny plates
! for the Indiana is finally judged and as
4 they viii doubtless take this chance to save
/ the 100000 which the plates cost. the next
trial may finally set at rest the doubt that
now exists as to the cause Of Saturdays
+ failure.