An Improved Method of Hardening or Converting into Steel the Surfaces of Iron Plates and other Objects made from Iron.
Year: 1893

page_text: Date of Application, 6th Dec., 1893
Complete Specification Left, 6th Oct., 1894-Accepted, 6th Dec., 1894
PROVISIONAL SOFEITICATION.
An Improved Method of Hardening or Converting into Steel the
Surfaces of Iron Plates and other Objects made from Iron.
I, EDWARD TRAVERS ZOHRAB c/o Duchy of Bronte, 3 Brabant Court
London E.C. Civil Engineer do hereby declare the nature of this invention to be
as follows:-
My invention relates to an improved method of hardening or converting into
in conjunction
steel the surface of iron plates and other objects made of iron and
with my Patent No. 3619 date of application 24th Feb. 1892 accepted 24th Feb.
1893 for the manufacture of peat and peat charcoal.
The said method consists essentially in providing a plate or other pieces of peat
charcoal of the same dimensions and configuration as those of the surfaces required
to be hardened; enclosing the plate, or pieces, of peat charcoal in a suitable frame
which is lowered on to the surface of the plate (which is maintained at a suitable
temperature as subsequently described) and hydraulic or other pressure is then
applied as long as is considered necessary to enable the carbon from the charcoal
to become absorbed and driven into the plate, thereby rendering the whole surface
equally hardened, whilst the portion of the plate beneath the surface is more or less
affected by the presence of the carbon being forced into it; and by this means
leaving the back of the plate of a much more toughened nature than hitherto has
been done, thereby making a greater resisting force to the impact of shot or shell
against the surface.
All air is excluded from the surface of the plate by having projecting edges to
the frame containing the peat charcoal.
In the case of objects of different shapes to that of a level plate, I make a frame
to conform to the curves or other shapes of the iron to be hardened and I further
make my charcoal plate to fit absolutely into said frame which I believe to be
unknown to any other inventor, as no wood or other charcoal can be produced in
such form & shapes.
As for example in the case of a shell or shells for ordinance, large or small,
I make the charcoal into the form of a hollow sphere in two halves and enclose the
same in corresponding iron or suitable frames these two half spheres being pressed
upon the periphery of the shell so as to entirely surround the same.
Dated this Fifth day of December 1893:
EDWARD TRAVERS ZOHRAB.
COMPLETE SPECIFICATION.
An Improved Method of Hardening or Converting into Steel the
Surfaces of Iron Plates and other Objects made from Iron.
I, EDWARD TRAVERS ZOHRAB, Engineer, of cio Duchy of Bronte, 3 Brabant
Court, London, E.C., do hereby declare the nature of this invention and in
what manner the same is to be performed, to be particularly described and
ascertained in and by the following statement :-
My invention relates to an improved method or process of hardening or con-
verting into steel the surface of iron plates and other objects made of iron.
My said invention is designed to provide for performing this operation in a more
efficient manner and in much less time than has heretofore been practicable..

page_text: For this purpose I carburize the iron by, heating the plate or other object to a
suitable temperature and placing against the surface thereof to be hardened a
correspondingly shaped piece of peat charcoal prepared substantially as described
in the Specification of former Letters Patent granted to me and dated
24th February 1892, No. 3619, and moulded to the required shape, and then
forcing the carbon into the iron to any desired depth by pressing the peat charcoal
against the said surface with a very heavy pressure, say from one to ten tons per
square inch, the pressure and temperature being maintained for a longer or shorter
period as may be found most advantageous. Good results are obtained by
continuing the treatment for from five to ten hours. In any case, the time required
for effecting the hardening is very much less than is necessary with the processes
hitherto adopted.
I find it advantageous to enclose the plates or pieces of peat charcoal in suitable
frames which are lowered on to the surface of the armour-plates or other. objects
to be treated. I then, while the charcoal and the armour-plate or other object are
maintained at a suitable temperature, press the charcoal against the iron by a very
heavy pressure, applied by means of a hydrostatic or other press or by other
convenient means, until the carbon from the peat charcoal is absorbed or driven
into the armour-plate or other object to the required depth. By this treatment, the
surface is rendered equally or uniformly hard, whilst the part of the armour-plate
or other object, for a greater or less depth, beneath the surface thereof is more
or less affected by the presence of the carbon forced into it; and the back of the
plate is left of a much tougher nature than hitherto. Therefore armour-plates thus
treated will offer a greater resistance to the impact of shot or shell against the
surface thereof, than the armour-plates heretofore used.
This
During the process, all air must be excluded from the surface of the plate.
is conveniently effected by having projecting edges to the frame containing the peat
charcoal, which edges are embedded in sand or the like, during the carburizing
process.
In the case of objects of different shape from that of a flat plate, I make the
frame to conform to the curvature or configuration of the surface to be hardened,
and I further make my charcoal plate to fit absolutely into the said frame. For
this purpose I grind to a suitable degree of fineness the bricks or blocks of peat
charcoal prepared as described in my said former Specification, and I mix the
powdered charcoal with a suitable binding material, such for example as molasses,
and mould the mixture to the required shape. It is by the use of my peat charcoal
that I am enabled to accomplish this result, as the wood or other charcoal
heretofore produced cannot be shaped as required for this purpose.
In the case of a spherical shell for ordnance, large or small, I make the charcoal
into the form of a hollow sphere in two halves and enclose the same in corresponding
frames of iron or other suitable material, these two half spheres being pressed upon
the periphery of the shell so as to entirely surround the same. For conoidal shot
or shell, I mould the peat charcoal into a hollow block which will fit accurately
upon the pointed end or head of the projectile.
In the accompanying drawing I have shown an apparatus adapted for the
treatment of armour-plates according to my said invention.
A is an oven or furnace which is shown in vertical longitudinal section and which
is constructed of fire-brick or other suitable material. The top of this oven or
furnace is provided with apertures a to permit the passage of the rams or piston-
rods of hydraulic presses, and with an opening provided with a suitable door c to
permit the entrance of a carriage B on which the armour-plate C to be hardened is
supported. The said oven or furnace is also provided with an opening d provided
with a door e to permit the insertion of the plate D of prepared charcoal or carbon,
and with such other apertures as may be necessary for the admission of air to
support combustion, for the inspection of the work, and for other purposes. In
the accompanying drawing I have shown sliding doors for closing the various
openings.

page_text: The carriage B consists of an iron frame having a depression or recess B¹ in.
which the plate C rests in such a manner that approximately half its thickness.
projects above the upper surface of the said frame. Around the outer edge of the
depression B is formed a recess or step B so that, when the plate C is in position,.
a groove or channel is formed around the outer edges of the said plate, which
groove or channel is filled with sand or the like. In order that the pressure applied
to the plate C shall not come upon the wheels f of the carriage B, I provide shoes
or bearings on the underside of the said carriage, which shoes, as the said
carriage passes into the oven or furnace A, slide up an incline onto supporting:
beds E, thus lifting the wheels f from the rails h.
The charcoal or carbon plate D which is to be applied to the upper surface of
the armour plate C is mounted in a frame F formed with a downwardly extending
flange or rim and with an internally projecting flange & for supporting the charcoal
or carbon plate D in the said frame. The said charcoal plate is inserted into the
frame F through the opening d and through an aperture F in the said frame,
the said aperture being provided with a suitable door so that air may be
excluded from the charcoal plate. The piston-rods G are worked by fluid-pressure
cylinders or in any other convenient manner and are surrounded by water.
jackets H to protect their outer surfaces from the heat of the furnace when the
frame F is lowered.
My improved method or process of hardening is carried into effect as follows,.
that is to say-The red hot armour-plate C having been run on the carriage B
into the previously heated oven or furnace A and onto the bed E as above described,.
the frame F is moved downward so that the charcoal or carbon plate D is brought
closely down against the upper surface of the armour-plate C, whilst the inner
edges of the flange k fit around the outer edges of the said armour-plate and the
downwardly projecting flange jis pressed down into the sand or other suitable
material placed in the groove or channel B' so as to exclude air or oxygen and thus
prevent the burning of oxidation of the carbon plate D and of the surfaces of the
armour plate C.
The doors being all closed, heat is applied to the plate C and D by means of the
gas-jets J and K arranged in rows along the underside and at the sides of
the carriage B, the underside of the said carriage having holes through it so that
the heat may the more readily act upon the plate C. The heat is applied so as to
maintain the temperature at from 1200 to 1500 degrees Fahrenheit, more or less
according to the depth to which it is desired the hardening shall extend into the plate.
Heavy pressure is at the same time applied to the frame F through the piston-rods G
so as to force the carbon into the heated armour-plate. The pressure necessary for
this purpose between the surfaces of the carbon plate and the armour-plate will be
from 1 to 10 tons per square inch according to the time allowed for the hardening
process and the desired depth of the hardening action. In some cases, however, it
may be desirable to apply a pressure of rather less than one ton per square inch or
of more than ten tons per square inch. The plate to be hardened is allowed to
remain in contact with the charcoal or carbon plate under the pressure and
temperature above mentioned for a period extending from say 5 to 10 hours, more
or less as may be deemed necessary or desirable, after which, it is removed from
the furnace and quenched by water-sprays or jets or in any other convenient
manner. In the case of thin plates or small objects, the hardening may be effected
by my process in much less time than five hours.
When it is desired to harden plates or other objects having a curved surface,
the supporting carriage is modified accordingly and the carbon plate is moulded
or otherwise shaped so as to exactly fit the surface to be hardened.
By ny improvements hereinabove described I am enabled to produce, in a much
shorter time than heretofore, a more evenly and efficiently hardened surface than is
practicable by the methods hitherto employed, without impairing the toughness of
the remainder of the plate or other object.

page_text: Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed I declare that what I
claim is
First. The hardening of iron by pressing peat charcoal against the surface of
the same under a very heavy pressure whilst maintaining the metal at a suitable
temperature.
Second. The herein described method or process of hardening or converting
into steel the surface of iron plates or other objects, consisting in heating the
same to a suitable temperature, applying to the surface thereof to be hardened a
piece of peat charcoal made to fit the said surface, and then forcing more or less
of the carbon into the metal by means of heavy pressure whilst maintaining the
temperature, substantially as herein before described.
Third. The use of a block or piece of peat charcoal for carburizing iron,
substantially in the manner hereinbefore described.
Fourth. The improved apparatus for hardening or converting into steel the
surface of iron plates or other objects, comprising a frame mounted on the
rams or piston-rods of fluid-pressure cylinders and formed with downwardly
and internally-projecting flanges, substantially as and for the purposes above
specified.
Fifth. The improved apparatus constructed substantially as described with
reference to the accompanying drawing, for the purposes specified.
Dated this 6th day of October 1894.
EDWARD TRAVERS ZOHRAB.
D. Young & Co.,
11 & 12, Southampton Buildings, London, W.C.,
Agents for the Applicant.