Pittsburg dispatch. [volume] (Pittsburg [Pa.]) 1880-1923, 1891-10-31
ARMOR PLATE TESTS
To Be Made at Indian Head To-day,
by the Government officials.
THE ELIMINATION OF A SERIES,
Which It Is Thought Will Settle a Long
Disputed Point.
THE DEVELOPMENT OF SUCH PLATES
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| WASHINGTON, Oct. 30.-What promises
to be in their results the most important
trials of armor plates ever yet made will be
commenced at the Indian Head naval ord
nance proving grounds tomorrow. These
| trials are the elimination of the series of
/ tests beginning'with the Annapolis trials of
September, 1890, undertaken by the Naval
Ordnance Bureau for the purpose of devel-
oping the ideal armour plate. In 1858,
when the great French naval constructor,
Dupuy de Lorne, built the Gloire, the Al
inches of iron he put on her sides was suffi-
cient to keep out the proiectiles from any
of the guns of that day. Then the guns
were improved, and later the projectiles, as
well, and SO. a constant strife for superiority
between guns and projectiles on the one
side and armor plates on the other was in
augurated and it is still in progress.
Of late the guns and projectiles seem to
have had somewhat the better of the battle,
owing to the perfection to which armor
piercing projectiles have been brought and
the high velocities attained with some of
the modern guns.
The Limit to Armor's Thickness.
The thickness in armor is necessarily
limited by the amount of weight that can be
given up to it, and in building q ship the
problem is, therefore, to devise an armor
plate that will be within these limitations
of weight and will yet keep the enemy's
projectiles out of the ship. The ideal armor
plate is one that is SO tough that the impact
or penetration of a proiectile will not crack
it, and is also so hard that the projectile will
be broken to pieces and will not get into the
ship.
The union of these qualities was aimed at
in the compound armor SO largely used in
the English navy, in which face of very
hard steel is welded to back of wrought
iron, the idea being that the hard face will
break up the projectile, while the soft iron
back will hold the plate together and pre-
vent cracking. This type of plate worked
very well so long as it was not attacked by
anything superior to chilled cast iron pro-
ectiles, but the tests of the last few years have
shown that, with the highly tempered
forged steel proiectiles of the present day
the compound plate cannot be expected to
stand up to its work.
Impossibility of Welding.
The hard steel face fails to shatter the
projectile, but is instead shattered itself
and usually large sections of it are broken
away from the backing, exposing the soft
CS.
It has been practically impossible to weld
the steel and the iron together well enough
to withstand the racking effect of the shot
Many naval authorities never had much
faith in the compound arrnor, and accord
ingly steel armor was developed, the most
successful makers being Schneider &
Co., of Creusot, France The
great difficulty with steel was to
combine hardness with toughness If the
plate was made tough enough to avoid
cracking it was apt to be so soft as to be
easily pierced, and if it was made hard
enough to keep out the shot it was very
liable to be cracked Even when cracked,
however, it was regarded bv its advocates
as superior to the compound plate, as it was
sure that the pieces fell from the backing,
and thus the protective value of the plate
was not entirely destroyed.
A Problem Yet to Be Solved.
To obtain practically the theoretical quail
ties of the ideal armor plate has been the
problem before the ordnance bureau. The
introduction of q small percentage of nickel
into steel gives it much additional tough
ness, as was shown by the ability of the !
nickel steel plate in the Annapolis trial to
withstand the tendency to crack, even when
attacked by an eight-inch projectile A
low percentage of carbon also gives tough
ness to the steel, while high carbon gives
great hardness. Advantage has been taken
of these facts, and an effort has been made
to produce the ideal plate by making plate
of low carbon nickel steel, and then, by the
Harvey process of surface carbonization,
giving it an exceedingly hard face, grad
ually shading off to the softer and tougher
back In this plate there is no troublesome
weld as in the common plate, and whether |
=, III Al,.1 / L.
series of trials will show.
The trials are to include all steel plates |
treated by the Harvey process, and un-
treated, and nickel steel, both treated and |
untreated. Eight plates will be fired at in
all, part of them being from Carnegie,
Phipps & Co. and the other from the |
Iron Works.