The Hartford republican. (Hartford, Ky.) 18??-1926, 1917-05-18
'ARMoRED VESSELS
How the Great Steel Plates That
Protect Them Are Made.
A. SEVERE TEST OF SKILL.
The Various Processes That Produce
tho Conflicting Properties Necessary
In These Modern Projsetiis Resisting
Warship Jackets.

Warship Jackets.
Only armored warships could live in
q naval battle with modern big gun
projectiles in use, and hence the max
ing of armOr plate has become a
science. The manufacture of armOr
plate has developed considerably In re-
cent years, and in no branch Of the
steel industry is there greater Oppor-
tunity for engineering aud mechanical
skill, coupled with mctalurglcal knowl-
edge, than in the operations of forging
and rolling. followed by the exact heat
treatment essential to produce the al
most conflicting properties necessary
In modern armor.
The plate must be hard, glass hard.
to resist penetration by heavy projec.
tiles moving at tremendous velocitics.
yet tough and tbrOUs enough TO take
up the momentum without cracking or
distortion. Mechanically. then, the
plate must have an extremely hard
surface and fibrous backing These
requirements were attained In part by
the old compound armOr. Molten stce!
was poured on to wrought iron plate
and cooled The slab was then re-
heated. forged aud rolled to the re-
quired dimensions. II the operations
were successfully carried out the line
of deinarcation was scarcely visible.
Recently a modification OF this proc
ess was introduced to cheaper and
render less tedious the production Of
armOr. A layer OF hard steel was
poured into a cooled mold, the under
side quickly setting. On the still fluid
or pasty surface a thick layer of soft
steel was poured. BY careful manipu-
lation the union OF the surfaces was
almost complete. and 1t was inpossl-
BILE to detect the break In composition
on viewing the fractured section. This
method of manufacture was undOubt-
eddy an Improvement Oh the old COM
pound method.
The increasing size. velocity aud
hardness OF modern armor piercing
projectiles have neccssitated the intro
duction OF the modern armor. The
process Of manufacture essentially
of about two inches the. surface OF
homogeneous tough nickel chrome
steel. Special air or self hardening
nickel and more complex steels are
used for lighter armor, gun shields
and cast armOrcd structures.
The steel is made in Siemens fur.
naces and carefully cast into ingots
up to eighty tons in weight. These in.
COTS are then stabbed under powerful
Hydraulic presses 0S,0oO tons) or roll
ell direct to the required dimensions,
depending on the power of the mills
and appliances During the rolling
operation. which lasts about an hour.
the slab is reversed and inverted to at
tain uniformity of working. and scale
is removed by wood fagots and WA
ter jets. After rolling the plate is
usually qucnched.
The next operation is that of case
hardening. and in this two plates are
put face to face, separated by a layer
OF the carburiZing reagcnt if 1t be
solid, or IL gaseous hydrocarbons be
used the plates are slightly separated,
TO allow free passage for the harden
ing gases. by bricks arranged In rows.
The plates are maintained at rcdneSs
In a car furnace for three weeks and
withdrawn after the hardening carbon
has penetrated to the required depth.
The plates are thus carburiZed and so
made capable of being hardened, but
they are not yet actually hard. At this
stage all holes are drilled and plugged.
and any bending OF machining ncces-
sary is carried out.
From this point onward the treat
ments differ. Some makers insist on
heating and qucnchins in oil or water
to remove any coarse structure that
may have been formed during the
long anneaiing while carburizinG The
next essential operation is that of
hardening, and this is usually car
ried out In one OF two ways. Either
the plate is uniformly heated 10 the
ha rdening temperature and uucnched !
by a series OF water jets playing On the /,
upper surface with sufficient force 10 |
prevent the formation of steam or by !
IIuNcNS kutNu as ulueTeIiHl I
quenchinG." by which the carburized /
surface is heated to temperature |
from which 1t will harden aud the |
under side kept well below. SO attaining |
u gradual fall in temperature from the ,
top TO the bottom The whole plate IL |
then immersed In water, the hotter sur
face alone being hardened, while the /
bark is toughened. Further mechanical
operations can he carried out only By |
grinding or cutting with oxyacetylcne,
as the plate mas nov undergone the
treatment comforting MAXIMUM hard.
ness.
In resume, II will be noted that there
are three distinct operations in modern
methods OF manufactured mechani-
cal working OF the plate 10 the required
the carhurizati0n OF thr
surface. qucnching the carhurizei
surface TO harden it, These operations
call for exact manipulation, super
vision and control. for the skill Of the
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