IMPROVEMENTS IN THE MANUFACTURE OF ARMOUR PLATES, AND IN THE MACHINERY OR APPARATUS. EMPLOYED IN SUCH MANUFACTURE."
Year: 1864

page_text: LETTERS PATENT to Henry Bessemer, of Queen Street Place, New Cannon
Street, in the City of London, for the Invention of "IMPROVEMENTS IN
THE MANUFACTURE OF ARMOUR PLATES, AND IN THE MACHINERY OR APPARATUS.
EMPLOYED IN SUCH MANUFACTURE."
PROVISIONAL SPECIFICATION left by the said Henry Bessemer at the
Office of the Commissioners of Patents, with his Petition, on the
30th January 1864.
I, HENRY BESSEMER, of Queen Street Place, New Cannon Street, in the
City of London, do hereby declare the nature of the Invention for "IMPROVE-
MENTS IN THE MANUFACTURE OF ARMOUR PLATES, AND IN THE MACHINERY OR
APPARATUS EMPLOYED IN SUCH MANUFACTURE," to be as follows:-
These improvements relate, firstly, to the manufacture of plates of cast
steel, or cast malleable iron. In manufacturing plates of these materials I
have observed that the coarse granular or crystaline structure of the metal
Cobservable in all masses of several inches in thickness) is greatly reduced
and modified in character when such masses are reduced by rolling to sheets
of from one-quarter to one-tenth of an inch, more or less, in thickness, and
that the molecular change so effected increases the tensile strength of the
metal, while the amount of bending or alteration in form which the metal will
bear without cracking or breaking is also thereby greatly increased. Cast
steel or cast 'malleable iron when reduced to, thin sheets by rolling will on

page_text: being annealed exhibit in its fracture a much more minute arrangement of
crystals than a larger section of the same quality of metal will do when
similarly annealed; hence it is seen that the peculiar toughness so desirable in
armour plates is obtained to a far greater degree in plates that have been
reduced to a small section than would be found in the same metal if manu-
factured in a large undivided mass. There is, however, this defect common to
the production of thick armour plates which are built up in piles or layers,
viz., that the original scale or coat of oxide of iron adhering to their surfaces,
and also the additional amount of oxidation which takes place in bringing]
them up to a welding heat prevents that perfect union of the several surfaces
in contact which is necessary for the developement of the entire cohesive and
resisting force of the material employed, and hence it is found that on a shot
penetrating an ordinary armour plate, large irregular masses are torn away
from the back of it, owing to the several plates of which it is composed being
imperfectly united or welded, in consequence of a portion of the coat of oxide
of iron being left between them.
Now, therefore, the object of the first part of my said Invention is the
manufacture of armour plates in such a manner, that while they retain to a
great extent the advantages derivable from the peculiar molecular arrangement
of. particles caused by rolling into thin sections, they may be afterwards so
united as to form solid masses, cohering so firmly as to constitute in effect a
Solid or undivided plate.
In carrying into practical operation this first part of my said Invention, I
cast an ingot of very mild steel, semi-steel, or soft malleable iron decarbonized
to the fullest extent practicable. I then proceed to hammer the same into a
flat slab, or I effect its compression by a hydraulic press, the slab having been
re-heated I roll it into a plate of such thickness as' will best suit the after part
of the process, prefering in most cases a very thin gauge. When a number of
such plates are rolled and sheared to a size preferably of one-third to one-half
of the area of the intended plate or mass, I proceed to cleanse the surfaces of
them by removing all the scale or coat of oxide by pickling in dilute sulphuric,
hydrochloric, or other acid, as practiced in preparing plates for tinning or
galvanizing. This cleansing of the surface may be assisted by friction, or it
may be wholly or in part effected by plunging the heated plates in cold water;
the plates when thus freed from all scale, and washed in clean, water, are to
be coated or painted over with a protecting material, prepared in a similar
manner to the glaze or enamel used to enamel iron and other metallic surfaces.
This coating may be a simple silicate of potash or soda, with or without an
addition of lime, alumina, salammoniac, or metallic oxides, but I prefer to

page_text: employ therewith some boracic acid, as it assists the fusion of the other
materials, and also the cleansing of the metallic surface. These materials
may be variously compounded without materially affecting the results obtained
by their use, the chief object being to obtain a glass of very easy fusion, and
possessing a great degree of fluidity. I prefer to make this glass or flux
either in crucibles, or on the hearth of a reverberatory furnace; the flux when
cold may be ground under edge stones into a powder, and be used with or
without an addition thereto of some of the raw materials before enumerated,
and be then mixed with as much water, or water and size as will facilitate its
application to the surfaces of the plates by a brush, or by immersion of the
plates therein. The plates after the cleansing by acid and coating with this
flux are to be dried, and then piled one on the other in the heating furnace,
and there kept until they have acquired a full welding heat, after which they
may be rolled in a powerful rolling mill into an armour plate of the desired
size and thickness. In this mode of treating plates it will be understood that
in the first operation the original coating of scale (common to all rolled iron
or steel plates) is removed, after which the coating of silecious matter will
defend the clean metallic surface of the plate from further oxidation while
being heated up to a welding heat, the pressure between the rolls afterwards
removing the fluid silicate, and allowing the iron or steel plates to make n
clean and secure weld. And although I have described the pile of cast steel
or cast malleable iron plates forming an armour plate as consisting of single
unjointed pieces produced from an ingot, I desire it to be understood that
such plates may be made by piling one or more plates, or one or more qualities
of cast malleable iron or steel, or scraps of such metal, and the plates so
produced may be piled to form the said armour plate. And although I have
described the mode of preparing the surface of plates as applicable to plates
composed of cast steel and cast malleable iron, I desire it to be understood
that such modes of cleansing. and preparing the surface of plates. may. be
applied to ordinary wrought iron, puddled iron, or scrap iron plates, and its
application thereto also forms part of my present Invention.
Secondly, my said Invention consists in alternating in the same armour-
plate sheets of metal differently manufactured, or of a different quality from
each other. Thus cast steel and cast malleable iron may be made to alternate,
each piece being of the same or of a different thickness; so, also, ordinary
puddled iron may be piled alternately with scrap iron, or either of these
qualities of iron may be piled alternately with cast steel or cast malleable iron.
Such compound plates either being rolled so as form plates to be afterwards
piled together and form the armour plate; or the armour plate may consist of the

page_text: original pile of plates of different quality without first welding them together;
or the armour plate may be built up of plates of cast steel that have under-
gone a process of decarbonizing in close chambers, the plates being stratified
therein with layers of oxide of iron or zinc, so as to wholly or partially decar-
bonize the said plates. In either of the modes of operating herein secondly
described, I employ the means herein firstly described, of cleansing and pre-
paring the surface of plates, so as to facilitate the perfect welding thereof..
Thirdly, my Invention consists in the mode of heating a pile of plates, and
consists in placing bars between the plates, so as to leave an open space
between them, and of heating the furnace by means of gas introduced at
opposite sides of the furnace alternately, so as to pass the heated matters
between the plates, and thus facilitate the heating of them. The separating
rods are then withdrawn, and the pile is to be further heated prior to rolling
it. For this purpose I prefer to generate, and apply the gases after the mode
now well known as "Siemen's regenerative furnace."
Fourthly, my improvements relate to the rolling mill employed to roll
armour plates, and consists in supporting the bearings of the lower roll on a
hydraulic ram connected with a raised tank or some other convenient source
of water pressure. A small hand valve will allow the workmen to admit
water beneath the ram, and raise up the bearings. to.a fixed stop. By closing
this valve, the water beneath the ram will form a support for the lower roll,
but in case the plate should stick between them, or the rupture of any part of
the driving gear should take place, or the engine should stop during the
rolling of a plate, then the workmen, by discharging the water from beneath
the said ram will release the plate from pressure, and allow it to be removed
with facility.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said Henry Bessemer in the Great Seal Patent Office on the
30th July 1864.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, HENRY
BESSEMER, of Queen Street Place, New Cannon Street, in the City of London,
send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by. Her Letters
Patent, bearing date the Thirtieth day of January, in the year of our Lord
One thousand eight hundred and, sixty-four, in the twenty-seventh year of
Her reign, did, for Herself, Her heirs and successors, give and grant 'unto

page_text: me, the said Henry Bessemer, Her special licence that I, the said Henry
Bessemer, my executors, administrators, and assigns, or such others as I,
the said Henry Bessemer, my executors, administrators, and assigns, should
at any time agree with, and no others, from time to time and at all times
thereafter during the term therein expressed, should and lawfully might
make, use, exercise, and vend, within the United Kingdom of Great Britain
and Ireland, the Channel Islands, and Isle of Man, an Invention for "IM-
PROVEMENTS IN THE MANUFACTURE OF ARMOUR PLATES, AND IN THE MACHINERY OR
APPARATUS EMPLOYED IN SUCH MANUFACTURE," upon the condition (amongst -
others) that I, the said Henry Bessemer, my executors or administrators, by
an instrument in writing under my, or their, or one of their hands and seals,
should particularly describe and ascertain the nature of the said Invention,
and in what manner the same was to be performed, and cause the same to
be filed in the Great Seal Patent Office within six calendar months next
and immediately after the date of the said Letters Patent.
.
NOW KNOW YE, that I, the said Henry Bessemer, do hereby declare
the nature of the said Invention, and in what manner the same is to be.
performed, to be particularly described and ascertained in and by the following.
statement thereof, that is to say :-
These improvements relate, firstly, to the manufacture of plates of cast steel
or cast malleable iron. In manufacturing plates of these materials I have
observed that the coarse granular or crystalline structure of the metal.
(observable in all masses of several inches in thickness) is greatly reduced
and modified in character when such masses are reduced by rolling to shects
of from one-quarter to one-tenth of an inch, more or less, in thickness, and
that the molecular change so effected increases the tensile strength of the
metal, while the amount of bending or alteration in form which the metal will.
bear without cracking or breaking, is also thereby greatly increased. Cast
steel or cast malleable iron when reduced to thin sheets by rolling will on
being annealed exhibit in its fracture a much more minute arrangement of
crystals than a larger section of the same quality of metal will do when
similarly annealed; hence it is seen that the peculiar toughness so desirable in.
armour plates is obtained to a far greater degree in plates that have been
reduced to a small section before referred to than would be found in the same
metal if manufactured in a large undivided mass. There is, however, this
defect common to the production of thick armour plates which are built up in.
piles or layers, viz., that the original scale or coat of oxide of iron adhering to.
their surfaces, and; also. the additional amount of oxidation which takes placo;
in bringing them. up. to a welding heat prevents that perfect union of tho.

page_text: several surfaces in contact, which is necessary for the developement of the
entire cohesive and resisting. force of the material employed, and hence it is
found that on a shot penetrating an ordinary armour plate (made by welding
several plates together) large irregular masses are torn away from the back of
it, owing to the several plates of which it is composed being imperfectly united
or welded, in consequence of a portion of the coat of oxide of iron being left
between them.
'
Now, therefore, the object of the first part of my said Invention is the
manufacture of armour plates in such a manner that while they retain to a
great extent the advantages derivable from the peculiar molecular arrangement
of particles caused by rolling into thin sections, they may bo afterwards so
united as to form solid masses, cohering so firmly as to constitute in effect a
solid or undivided plate.
In carrying into practical operation this first part of my said Invention, I
cast an ingot of very mild steel, semi-steel, or soft malleable iron decarbonized
to the fullest extent practicable; I then proceed to hammer the same into a
flat slab, or I effect its compression by a hydraulic press, the slab having been
reheated I roll it into a plate of stich thickness as will best suit the after part
of the process, preferring in most cases a very thin guage. When a number
of such plates are rolled and sheared to a size preferably of one-third to one-
half the area of the intended armour plate, I proceed to cleanse the surfaces
of them by removing all the scale or coat of oxide by pickling in diluto
sulphuric, hydrochloric, or other acid, as practised in preparing plates for
tinning or galvanizing. This cleansing of the surface may be assisted by
friction, or it may be wholly or in part effected by plunging the heated plates
in cold water; the plates when thus freed from all scale and washed in clean
water are to be coated or painted over with a protecting material prepared in
a similar manner to the glaze or enamel used to enamel iron and other metallic
surfaces. This coating may be a simple silicate of potash or soda, with or
without an addition of lime, alumina, salammoniac, or metallic oxide, but I
prefer to employ therewith some boracic acid, as it assists the fusion of the
These
other materials, and also the cleansing of the metallic surface.
materials may be variously compounded without materially affecting the
results obtained by their use, the chief object being to obtain a glass of very
easy fusion, and possessing a great degree of fluidity. The silicate of the
be
oxide of iron or "cinder" produced in balling or reheating furnaces may
employed along with other siliceous matters, or it may be reduced to powder,
and used alone or with about a fourth part of boracic acid; I prefer to make
this glass or flux either in crucibles or on the hearth of a reverberatory

page_text: furnace; the flux when cold may be ground under edge stones into a very fine
powder, and be used with or without an addition thereto of some of the raw
materials before enumerated, and be then mixed with as much water or water
and glue size as will facilitate its application and adhesion to the surfaces of
the plates; this coating of the plates may be effected by a brush or by the
immersion of the plates in a bath of the semifluid matter. The plates after the
cleansing by acid and coating with this flux are to be dried, and then piled one
on the other in the heating furnace, and there kept until they have acquired a
full welding heat, after which they may be rolled in a powerful rolling mill
into an armour plate of the desired size and thickness. In this mode of
treating plates it will be understood that in the first operation the original
coating of scale (common to all rolled iron or steel plates) is removed, after
which the coating of siliceous matter will defend the clean metallic surface of
the plate from further oxidation while being heated up to a welding heat, the
pressure between the rolls afterwards removing the fluid silicate, and allowing
the iron or steel plates to make a clean and secure weld. And although I have
described the pile of cast steel or cast malleable iron plates forming an armour
plate as consisting of single unjointed pieces produced from an ingot, I desire
it to be understood that such plates may be made by piling two or more plates
of the same quality of metal, or two or more qualities of cast malleable iron
or steel or scraps of such metal, and the compound plates so produced may be
piled to form the said armour plate; in either case the plates intended to
form the armour plate pile, and which have been built up in two or more
pieces, should have each been cleansed from scale and coated with flux in the
manner herein-before described, and when rolled out to the proper size should
be again cleansed and coated prior to their formation into a pile intended to
be rolled into an armour plate, and although I have described the mode of
preparing the surface of plates by pickling and coating them as applicable to
plates composed of cast steel and cast malleable iron, I desire it to be under-
stood that such modes of cleansing and preparing the surface of plates may be
applied to ordinary wrought iron, puddled iron, or scrap iron plates, and its
application thereto also forms part of my present Invention.
Secondly; my said Invention consists, in alternating in the same armour
plate sheets of metal differently manufactured, or of a different quality from
each other, thus cast steel and cast malleable iron may be made to alternate,
each piece being of the same, or of a different thickness, so also ordinary
puddled iron or scrap iron may be piled alternately with cast steel, or with
cast malleable iron, such compound plates either being rolled so as to form
separate plates, to be afterwards piled together, and thus form 'the armour

page_text: plate, or the armour plate may consist of the original pile of plates of different
quality without first welding them together, or the armour plate may be built
up of plates of cast steel that have undergone a process of decarbonizing in
close chambers, the plates being stratified therein with layers of oxide of iron
or zinc, so as to wholly or partially decarbonize the said plates in either of
the modes of operating herein secondly described, I employ the means herein
firstly described of cleansing and preparing the surface of plates so as to facili-
tate the perfect welding thereof.
s.
Thirdly, my Invention relates to the mode of heating a pile of plates, and
consists in placing, bars between the plates so as to leave an open space
between them, 'and-of heating the furnace by means of gas introduced at:
opposite sides of the furnace alternately so as to pass the, heated matters
between the plates and thus, facilitate the heating of them. The separating
rods, which have an eye formed at one end of them, are then withdrawn
through suitable openings made in the side of the furnace, and the pile is
to be further heated if necessary prior to rolling it. For this purpose I prefer
to generate and apply the gases after the mode now well known as "Siemens".
regenerative furnace.
The mode of separating the pile by bars or rods of iron for the purpose
of facilitating the heating of the interior portions of the pile will be under-
stood by reference to Figure 2 on the Sheet of Drawings hereunto annexed,
where a represents the plates of which the pile is composed, and n the rods
employed to keep them apart from each other.. The plates may each have
rods between them, or two or more plates may be placed together between a
set of rods as will be found preferable when the pile is composed of very thin
plates.
:
Fourthly, my improvements relate to the rolling mill employed to roll
armour plates, and consists in supporting the bearings of the lower roll on a
hydraulic ram connected with a raised tank or some other convenient source
of water pressure. A small hand valve will allow the workmen to admit
water beneath the ram, and raise up the bearings to a fixed stop. By closing
this valve the water beneath the ram will form a support for the lower roll,
but in case the plate should stick between them, or the rupture of any part
of the driving gear should take place, or the engine 'should stop during the
rolling of a plate, then the workmen by discharging. the water from beneath
the said ram will release the plate from prossure, and allow it to be removed
with facility.
.
.
On the Sheet of Drawings hereunto- annexed I have shewn at Figure 1.
an elevation of the side frame or "housing" of a rolling mill the lower part
.

page_text: is shewn in section. 6 is the main casting, the lower part.of which.is, formed
into a shallow cylinder c, into which the ram d is fitted, and is kept water-
tight by a leather ring e. The upper part of the ram is rectangular in form
as shewn at d*.which serves. as the block and supports upon it. the block in
which the brass bearing g is fitted, and also supports the neck of the lower
roll h. A pipe leading to a raised tank or to some other convenient source of
water pressure is connected with the cylinder at i, so that by the opening
of a valve or cock on the said pipe water may flow into the cylinder and
raise the ram d until the parts d* are forced firmly up against the stops b*
formed on the main frame b, the cock or valve is then to be closed so that
the water beneath the ram may be retained and form a firm support for the
brasses in which the lower roll: necks revolve. It will be understood that
the frame at each end of the rolls is similarly constructed that each end of
the lower roll is supported in water in the manner described. A cock m is
also provided for each frame or "housing" for the discharge of water from
beneath the ram d, or by preference a pipe in communication with the water
spaces beneath each ram may lead to any convenient spot where a valve or
cock may be made to discharge water simultaneously from beneath both rams
without the workman having to approach the roll frames for that purpose.
Having described the several parts of my Invention, and the manner in
which the same may be carried into practical operation, I desire it to be
understood that I do not confine myself to the precise details herein given,
provided the essential parts of my said improvements be retained, but what I
claim,
Firstly, in the manufacture of armour plates composed of cast steel or of
cast malleable iron, is the removal of the scale or oxide from the surfaces
of the several plates forming the pile, and the coating of such surfaces with a
fusible flux as described.
Secondly, I claim in the manufacture of armour plates composed of puddled
or scrap iron, or partly of puddled or scrap iron, and partly of cast malleable
iron or steel, the removal of the scale or oxide from the surface of the several
plates forming the pile, and the coating of such surfaces with a fusible flux as
described.
Thirdly, I claim forming armour plates by piling alternately plates of cast
steel and plates of cast malleable iron.
Fourthly, I claim forming armour plates by piling alternately cast steel or
cast malleable iron plates, with other plates made of puddled iron or scrap
iron.
Fifthly, I claim in the manufacture of armour plates separating the several

page_text: plates composing the pile (during the heating of them) by means of bars or
rods placed between the several plates.
Sixthly, I claim the mode herein described of releasing the armour plate
from pressure when desired by discharge of water from the rams placed
beneath the brasses of the lower roll.
In witness whereof, I the said Henry Bessemer have hereunto set
my hand and seal, this Twenty-ninth day of July, in the year of our
Lord One thousand eight hundred and sixty-four.