Improvements in Compound Steel Armour Plates and in the Manufacture thereof.
Year: 1889

page_text: Date of Application, 27th June, 1889
Complete Specification Left, 8th Feb., 1890--Accepted, 8th Mar., 1890
PROVISIONAL SPECIFICATION.
Improvements in Compound Steel Armour Plates and in the
Manufacture thereof.
I, JAMES YATE JOHNSON of 47 Lincolns Inn Fields in the County of Middlesex
Gentleman do hereby declare the nature of this invention which has been communi-
cated to me from abroad by Carl Pieper of 109-110 Gneisenaustrasse Berlin S.W.
in the Empire of Germany Engineer to be as follows :-
This Invention relates to a form of armour plate composed of a number of
thicknesses or layers of metal of different hardness and tenacity or toughness and to
the manufacture of the same. The invention consists in the first place in improved
compound plates in which the individual thicknesses or layers of metal such for
example as hard steel and soft tough steel or cast iron are so arranged that reckoning
from a plane in the interior of the compound plate the hardest layer is inwards
being enclosed outwardly on both sides by a softer layer or the hardest layer-hard
steel for example-is covered on both sides with a layer of less hard steel, this less
hard steel being again covered by a still softer layer of metal such for example as
soft tough steel or cast iron.
In any case the several layers or thicknesses are united or caused to adhere together
as intimately as possible by fusing or welding.
In the production of these compound armour plates the metals employed in the
formation of the several layers or thicknesses are cast either simultaneously or in
immediate succession in a mould provided with as many compartments as there are
different layers or thicknesses in the manufactured plate. For example a mould
employed in the manufacture of a plate with a hard internal core placed between two
softer layers is made with three compartments. This mould preferably consists of a
shell in which is placed a box made of sheet iron or steel or of dressed cast steel the
sides of this box being made so thin that they are completely or almost completely
fused between the hard and soft metal run into the box and into the mould on each
side thereof. By these means the several layers or thicknesses are firmly united at
their surfaces of contact.
According to another arrangement the mould may be constructed with thin
inserted plates extending the whole width of the mould being placed at distances
apart corresponding to the thicknesses of the several layers of metal and suitably
supported or retained in position relatively to one another and to the shell.
It is evident that in the manufacture of compound plates with metal of three
different degrees of hardness and toughness the inner metal forming a layer enclosed
between the two others the hardest piece being in the middle the softest outside and
the intermediate degree of hardness between the two, the mould or shell is provided
with two boxes with thin sides or with four inserted partitions so as to form five
cells or compartments. The two outer and the two intermediate compartments are
preferably simultaneously filled with soft and with somewhat harder steel respectively
in the first place the hardest steel being subsequently introduced into the middle or
central compartment.
In certain cases boxes closed at the lower part are employed being maintained at
a suitable distance from the bottom and from the top of the shell or mould by means
of supports or bearers and stays or retaining rods or the like to prevent them from
rising.
This arrangement is employed for the production of compound plates or blocks
having an inner or central core or layer of hard metal enclosed at the edges or ends
as well as at the sides in an outer layer or layers of softer metal.
A compound plate or block produced as hereinbefore described may be subjected

page_text: to any ordinary or suitable finishing process or processes of manufacture such as
rolling forging or pressing in order to obtain a compound armour plate of the
desired shape and thickness. The superfluous soft steel may be removed from the
plate by planing or otherwise if necessary or desirable.
Dated this 27th day of June 1889°
J. H. JOHNSON & Co.,
47, Lincoln's Inn Fields, London, Agents.
COMPLETE SPECIFICATION.
Improvements in Compound Steel Armour Plates and in the
Manufacture thereof.
I JAMES YATE JOHNSON of 47 Lincolns Inn Fields in the County of Middlesex
Gentleman do hereby declare the nature of this Invention (which has been com-
municated to me from abroad by Carl Pieper of 109-110 Gueisenaustrasse
Berlin S. W. in the Empire of Germany Engineer) and in what manner the same is
to be performed to be particularly described and ascertained in and by the following
statement:-
This Invention relates to a form of armour plate composed of a number of
thicknesses or layers of metal of different degrees of hardness and tenacity or
toughness and to the manufacture of the same.
The compound armour plates heretofore employed whether composed of a thick-
ness of hard steel and a thickness of wrought iron welded thereto or of a thickness
of hard steel with a thickness of soft steel or ingot iron welded thereto are without
exception employed in such a manner that the layer of hard steel is placed on the
side which is directly exposed to the impact of projectiles. When a plate of this
description is exposed to the action of a number of shots of correspondingly
increasing force large pieces of the hard steel are frequently cracked or splintered
off. This is more liable to happen in proportion as the hardness of the hard steel
relatively to that of the soft layer welded thereto at the back is increased and also in
proportion to the difference between the melting temperature of the two thicknesses.
When one plate is hit by a number of projectiles the compound plates thus
constructed are more easily bent or put out of shape in proportion to the hardness
and brittleness of the layer of steel. On the other hand it is important to employ
plates constructed with hard steel for protection against hard steel projectiles
especially when the latter are propelled by high explosives.
The present Invention is designed to obviate the disadvantages of the ordinary
compound armour plates by providing plates which whilst destroying the force of the
projectile by the resistance presented by a thickness of hard steel at the same time
possess the toughness of a soft plate so as to avoid the distortion and cracking off of
the hard layer. This result is obtained when the compound plate is manufactured
in the manner hereinafter described so that the layer of hard steel is not situated at
the exterior but is placed in the interior of a plate of soft tough steel or ingot iron
the welding together of the layers being effected in the operation of casting the
ingot from which the plate is subsequently formed by rolling forging or pressing.
And in order that the said Invention may be fully understood I shall now proceed
more particularly to describe the same and for that purpose shall refer to the several
figures on the annexed sheet of drawing the same letters of reference indicating
corresponding parts in all the Figures.
In a shell or mould a illustrated in vertical section in figure 1 is placed a box b
of sheet iron or steel; the hard steel is poured into the box-b (preferably through a
funnel at the top of the box) and the soft steel is poured into the space between the
mould a and the said box being preferably introduced at the bottom through the
passages indicated in dotted lines. The pouring of the hard and soft steels should
be effected as nearly simultaneously as possible but one kind of steel may be poured
first, the other kind being poured immediately thereafter.

page_text: The sheet metal box which confines the hard steel is made of metal of suitable
thinness to enable it to be completely or almost completely melted by the hard steel
inside it and the soft metal outside it. In place of being made of sheet iron or stee!
this box may be made of cast steel which can be partly or wholly melted by the metal
poured in, in the same way as the sheet metal box.
By means of this arrangement the thickness of the layer of hard steel in the
finished plate as well as the thickness of the layer of softer steel on the front and
back of the said plate are enabled to be determined before the operation of casting
or pouring the ingot. For example, in case the thickness of hard steel in the finished
plate is to be one third of the total thickness of the plate the width of the box at c in
the plan figure 2 must be made equal to one third of the width of the inside of the
mould or outer case a (indicated at d). To obtain an equal thickness of soft steel at
the front and at the back the box 6 must be adjusted in the mould or outer case in
such a manner that the spaces on each side at e and are equal but when these
thicknesses are not to be the same the box b must be shifted to a suitable extent to
one side.
The compound ingot obtained by these means is worked up into a finished plate in
the usual manner. In heating the ingot for the rolling forging or pressing process
the hard steel is liable to be over-heated where exposed in the furnace and to get
burned at the parts g g figure 1. where it is directly exposed to the furnace heat.
This contingency may be conveniently provided against by employing a box closed
at the bottom as indicated in vertical section at i figure 3, this box being filled
with the hard steel up to its top edges k the soft steel being then poured into the
intermediate space until it rises above and completely covers in the hard steel. In
this case the box b stands upon light supports el which are partially melted in the
soft steel at h, the box being also prevented from rising by suitably arranged
retaining bars m at the top.
In place of so casting the ingot as to form a layer of hard steel inside enclosed in
a softer layer cast around it the plates may, when such a combination is considered
desirable be produced with steels of three different degrees of hardness and toughness,
the inner and hardest layer being imbedded in a layer of hard steel somewhat
softer than the first and this second layer being in turn enclosed within a steel of a
still softer nature. By these means five welded thicknesses of steel are obtained as
represented in the section figure 4 the two outer thicknesses being the softest
and toughest the next inner layers y y being relatively hard and the central layer
being composed of the hardest steel. In casting the ingot for this plate the soft
steel and the intermediate steel y are first poured into the mould simultaneously
the hard steel being poured in last. Two sheet metal boxes must be placed in the
mould.
According to another arrangement in place of pouring in the soft steel all round
the hard steel two thicknesses win figure 5 of soft steel may be simply cast on
opposite sides of a thickness p of bard steel by introducing into the mould two
thin flat plates 6' 6' of steel or iron forming partitions being supported at a suitable
distance apart by light iron or steel distance pieces or packing blocks o.
In this case
the two soft layers u and the central hard layer p are likewise poured in simul-
taneously. The superfluous soft steel at the edges of the plates may be removed
from the finished rolled or forged plate as represented in figures 6 and 7 by a
planing or analogous trimming operation or if preferred a suitable width of the
soft metal may be allowed to remain at the edges.
The front layer of soft tough steel or ingot iron in this armour plate presents the
advantage that when the plate is hit even by a considerable number of shots the hard
facing cannot be cracked off being held together by the soft front layer even after
the hard steel is fractured.
The metal found to be best adapted for the purposes of this Invention is that
form of cast iron known as ingot iron.
Another important advantage attending the employment of the armour plates
manufactured according to this Invention for armoured vessels is that when a portion

page_text: of the plate below the water line has to be bevelled or planed off at an angle as
represented in figures 8 and 9 the layer of hard steel indicated at 7 figure 9 is not
reduced whereas in the case of the ordinary compound plate illustrated in figure 8
the hard layer 9 destined to resist the penetration of the projectile is necessarily
reduced or cut away.
I am aware that it is not new in the manufacture of compound armour plates to
pour hard and soft qualities of steel simultaneously into a mould divided by a partition
plate.
I am also aware that Patents have been taken out for the manufacture of
compound armour plates in which bars of iron or steel arranged in the mould in the
form of a grid or grating are embedded in the steel. The employment of these bars
is said to render the plates tougher and render them less liable to be distorted by
the impact of projectiles. It is also found that bars of softer material embedded in
the plate increase its strength or power of resistance.
The feature of novelty in the present Invention resides in the production of
compound armour plates having a layer or thickness of relatively soft steel or ingot
iron on both sides of a layer or thickness of hard steel and in which the soft and
hard metals are united by being poured into the mould either simultaneously or one
immediately after the other.
Having now particularly described and ascertained the nature of the said Inven-
tion and in what manner the same is to be performed I declare that what I
claim is :-
1. A compound steel armour plate produced from a steel ingot by rolling forging
or pressing and composed of layers or thicknesses of different degrees of hardness
and toughness welded together, being so combined that on each side of the central
plane the harder layer or layers is or are covered on the outer side by a layer or
layers of softer and tougher metal substantially as herein before described.
2. The manufacture of compound steel ingots for the compound steel armour plates
berein before described and claimed by pouring the different qualities of metal either
simultaneously or one immediately after the other into the corresponding compart-
ments of a mould provided internally with one or more boxes baving thin sides or
with partition plates and distance or packing pieces and with or without bottom
supports (e figure 3) and retaining bars (m figure 3) substantially as hereinbefore
described with reference to the accompanying drawings.
Talth: 9th of 1000