AN IMPROVED PROCESS FOR STEELIFYING IRON
Year: 1873

page_text: LETTERS PATENT to Thomas Sheehan, of Great Portland Street, in the
County of Middlesex, for the Invention of "AN IMPROVED PROCESS
FOR STEELIFYING IRON."
Sealed the 3rd February 1874, and dated the 2nd October 1873.
PROVISIONAL SPECIFICATION left by the said Thomas Sheehan at the
Office of the Commissioners of Patents, with his Petition, on the
2nd October 1873.
I, THOMAS SHEEHAN, of Great Portland Street, in the County of
Middlesex, do hereby declare the nature of the said Invention for
"AN IMPROVED PROCESS FOR STEELIFYING IRON," to be as follows :—
My Invention relates to improvements in the process of steelifying
iron, for which I obtained Letters Patent, bearing date May 13th, 1872,
No. 1454, and consists more particularly in the addition of sulphate of
soda to the other ingredients therein mentioned, and in the omission of
the_rosin, and also in-the-employment-by-means-of-a-perforated-iron
plate of a layer of limestone at the top of the box in which the steelifying
_process_is_effected-in-addition-to-that-at-the-bottom.
+

page_text: In carrying out this process I therefore employ the following
ingredients, namely, No. 1, common salt; No. 2, carbonate of soda (or
sal soda); No. 3, sulphate of soda; No. 4, hard wood or peat charcoal
broken small and sifted through a No. 4 sieve; No. 5, black oxide of
manganese; No. 6, raw limestone.
I take a sufficient quantity of the ingredients, Nos. 1, 2, and 3 in the
following relative proportions (which I merely give by way of example,
as they may be varied according as it is desired to steclify the iron to a
creator loss doprinet:
and mix the same in a separate vessel with as much water as will dissolve
them and no more.
"
I then take of No. 4 as much as will be sufficient to make a thick
paste with the above solution and mix it thoroughly (when in a dry
state). with 6 lbs. more or less of No. 5 in a separate vessel called.
the supply box. then take the said solution-of-Nos.-1,-2, and 3,
and incorporate it thoroughly with the mixture of charcoal-and-man-
ganese. This which. I now term the charcoal compound is then ready
for usc. I thich take a suitable box of wrought or cast-iron-in-size-
fit for the work intended to be steclified. I then take No. 6 (raw
limestone) broken small, about the: size of peas; and put a layer of
the broken limestone, about 1 inches thick, more or less, in the
bottom of the said box. I then take a plate, of thin slicet iron per-
forated with small holes (say inch, set one inch apart, more or less)
and place the plate loosely on the limestone inside of the box. I then
put a layer of the said charcoal compound on the top of the said per-
forated plate, two inches thick, more or less, then a layer of the work
intended to be steelified is put on this layer of the compound, and
alternate layers of iron and of the compound aro put on until the box
is nearly full, care being taken to finish with a layer of the charcoal.
compound on the top, about 2 inches, more or less. Upon this layer I
place a perforated tray similar as regards the thickness and the holes to
the perforated plate before mentioned and containing a layer of the raw
limestone broken small; about one inch in depth, more or less. This
tray is made rather less in width and length than the box in which it is
placed, so as to leave a space all round to allow the carbon to pass and

page_text: penetrat the contents of the box. I then put a suitable cover on the
said box and lute it with fire-clay or yellow mud, and make a small hole
(about inch) in the end of said cover to let the steam escape while
heating. Then I put the said box in an open fire or furnace, preferably
a furnace, and subject the box to a strong heat, from 2 to 16 hours,
according to the size of the box, and the bulk of iron, and the depth to
which the said iron is intended to be steelified. Then I remove the
pieces from the box, one by one, and clean each with a brush and chill it
in a sufficient body of clear cold water. There will then be a uniform
coat of actual steel on the entire surface of the work to the depth
required, according to the time it is left in the fire. I then remove the
residue, which should not be wasted, and cool it with the solution of
Nos. 1, 2, and 3, as first used to form the charcoal compound. This
residue must be cooled off while it is hot on a piece of sheet iron or in an
iron box made for the purpose. The residue will then be ready to be
turned into the supply box for use again. The more it is used the better
and stronger it will be.
Nothing further is required to be renewed at the successive batches
except the limestone, which, when withḍrawn from the box, will be good
burned lime, and may be used as such. This process does not spring
or scale the work, or make it brittle, as in the old method of case
hardening.
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said Thomas Sheehan in the Great Seal Patent Office-
on the 20th March 1874.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, THOMAS.
SHEEHAN, of Great Portland Street, in the County of Middlesex, send
greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by. Her
Letters Patent, bearing date the Second day of October, in the year
of our Lord One thousand eight hundred and seventy-three, in the
thirty-seventh year of Her reign, did, for Herself, Her heirs and suc-
_cessors,-give-and-grant unto me, the said Thomas Sheehan, Her speciāl
licence that I, the said Thomas Shechan; my executors, administrators,
and assigns,-or-such-others-as-I, the said Thomas Sheehan, my executors,

page_text: 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 "AN IMPROVED E
PROCESS FOR STEELIFYING IRON," upon the condition (amongst others) that
I, the said Thomas Sheehan, 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 1
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 Thomas Sheehan, do hereby declare
the nature of my said Invention, and in what manner the same is to be 1
performed, to be particularly described and ascertained in and by the
following statement (that is to say) :—
My Invention relates to improvements in the process of steelifying iron
for which I obtained Letters Patent bearing date May 13th, 1872,
No. 1454, and consists more particularly in the substitution of sulphate of
soda as an ingredient in the solution (employed as hereafter described) for
and in the place of pulverized rosin in the dry mixture at first prepared ;
and in the employment of an additional layer of limestone kept separate,
by means of an additional perforated iron plate or its equivalent, from
the compound (termed the charcoal compound) surrounding the work, a
the said additional layer of limestone (with its additional perforated
plate) being placed upon the said compound, so that it exercises its
function at the top of the box or chamber in which the steelifying process
is effected in combination with a first, or with another, layer of limestone
placed at the bottom of said box or chamber, said first or other layer
being also separated by a perforated plato from the said compound.
In carrying out this process I therefore employ the following
ingredients, namely, No. 1, common salt; No. 2, carbonate of soda (or
sal soda); No. 3, sulphate of soda; No. 4, hard wood (or peat), charcoal
broken small and sifted through a No. 4 sieve (employing only what
shall have passed through the sieve); No. 5, black oxide of manganese;
No. 6, raw limestone.

page_text: I take, according to the operation to be undertaken, a sufficient
quantity of the ingredients Nos. 1, 2, and 3, in the following relative pro-
portions, which I give by way of example, as they may be varied
according to the bulk of the iron operated on and the depth to which it
is intended to be steelified :-
-
is intended to be steelified :-
No. 1.
-
-
60 lbs.
No. 2.
-
30 lbs.
No. 3.
-
30 lbs.
and mix the same in a separate vessel with as much water as will
dissolve them and no more.
I then take of No. 4 as much as when combined with the above
solution will make a thick paste. Before so combining these, and while.
this quantity of No. 4 is in a dry state, I first carefully mix it as
thoroughly and equally throughout as possible with 6 lbs., more or less,
of No. 5 in a separate vessel, which I call the supply box. I then
thoroughly incorporate the said solution of Nos. 1, 2, and 3, with the
said dry mixture of charcoal and manganese. This, which I now term
the "charcoal compound," is then ready for use. I then take a suitable
box, which may be made of wrought or cast iron, in size adapted to the
work intended to be steelified.
I then place in the bottom of the said box a layer 1½ inches, more or
less, of No. 6 (raw limestone), broken small, about the size of peas. I
then place loosely upon the said layer of limestone a plate of sheet iron
(say about 1/8 th inch thick) fitted nearly to the inside dimensions of the
box, and perforated throughout with small holes (say tinch) set one-inch
apart, more or less. I then put on the top of, that is to say above, the
said perforated plate, a layer two inches thick, more or less, of the said
charcoal compound. Then, upon the said layer of the compound I place
a layer of the ironwork intended to be steelified, then a layer of the
compound, and alternate layers of iron and of the compound are put in
until the box is nearly full, care being taken to finish with a layer about
two inches thick of the compound at the top. Upon this last layer of
the compound I place a sheet-iron tray perforated throughout the flat
of it, and as regards the thickness and the holes in it, similar to the last
before mentioned perforated plate-that-has-been-placed-next above¯the
limestone layer at the bottom of the said box or-chamber. In or upon.
said top tray or plate I.put.a.layer-one-inch, more-or-less, in-depth of

page_text: raw limestone (No. 6) broken small as before described. The said top
tray or plate is made rather less in length and breadth than the inside
of the box in which it is placed so as to leave all about it between it
and the box nearly or about an inch of space in order to allow the
carbon as climinated from the top layer of limestone to pass down over
the tray edges and penetrate the contents of the box. I then put upon
the said box a suitablo cover, in the top, near to one end, of which cover
I previously make a small hole (about inch) to allow the steam
generated-while-the contents of the box are heating, to escape. And I
lute the cover with fire-clay or yellow mud.
Then I put the said box thus prepared and charged in an open fire
or furnace, preferably in a furnace, and therein subject the box to a
regulated steady strong heat (a bright red heat) for from 2 to 16 hours,
according to the size of the box, the bulk of the iron operated on and the
depth to which the said iron is intended to be steelified. Theṛcupon
the entire surface of the ironwork so treated will have become converted
to the depth required into an uniform coat of permanent actual steel.
When desired to turn out the work with the steel hardened I remove
it from the box, clean off with a brush, and as cleaned, chill-in-a-sufficient__
body of clear cold water, one by one each of the pieces while yet red hot.
of the iron operated upon. When this is done the surface steel will be
found to have acquired a peculiar (and all but diamond) hardness.
The compound should not be wasted after use, but when brushing off
the pieces as withdrawn it should be returned to the residue remaining
in the box, which residue I then remove from the box, and cool it off
with the solution of Nos. 1, 2, and 3, as prepared and used at first to form
the "charcoal compound." The solution must be poured upon the
residue while it is hot on a piece of sheet iron, or preferably in an iron
box made for the purpose. The residue will then be ready to be turned
into the supply box as compound for use again. The more it is according
to theso instructions reused and treated the better and stronger it will
become, and this re-using can be continued almost ad infinitum, or until
by the mere waste of spilling in handling it is at length slowly lost.
Nothing further is required to be renewed except the limestone, which
when withdrawn from the box will havo become and will have the full
value of, good burned lime, and may be used or (if preferred and on
sufficient scale) sold as such, and is always worth the cost of the lime-

page_text: stone plus a lime burner's cost of burning, and therefore exchangeable
for its equivalent in raw limestone, so that it may be made to be practi-
cally of no further cost after the first quantity is procured, the value of
the product thus continuing to replace the cost of further supply if
desired. By this process wrought iron can without fusion be expedi-
tiously and economically converted to the depth intended throughout its
entire surface into good actual steel.
"
Taking into consideration the great number of times that the com-
pound can be reused the perfect external steelification of the iron that I
thus effect does not cost a sixth part as much as even the old method of
case hardening," with which however my process should by no means
be confounded, but should on the contrary be distinguished as original
and wholly different from that in principle, in the whole combination of
chemical and mechanical means employed, in its plan, method, and result.
Instead of the mere cystallized iron surface which on the application
of heat could be made to return to the state of common iron again, and
which is the general result of nearly if not all those former processes
known as the "old method of case hardening," my process (in its first
stage in my first before-mentioned Patent, and the now specified more
full developement also of my Invention) converts the exterior of the iron
into a pure and permanent steel, of a quality that takes the hardest
temper, that can be re-heated, re-tempered, melted, and otherwise be
made to undergo any treatment admissible by any known steel. I also
avoid the great objection to the old "case-hardening" processes, that,
owing to the length of time that in all those old processes the iron is
subjected to the furnace heat, the fibre and quality of the iron remaining
is generally burnt or otherwise injured and deteriorated, whereas the
remaining iron after my process is greatly improved in quality and
condition. Experience is now constantly demonstrating that a coat of
one-eighth of an inch of permanent steel capable of exceptional
hardness is by my process obtained in six hours of the furnace heat,
in every respect and for every purpose superior to, the best of what
has been called case hardening that can be obtained in 36 hours.
Besides this comparative great economy my process has the further
important advantage that it does not spring. or scale the work, or
make it brittle as does the old method of casé hardening, and can
therefore be advantageously applied to wrought iron in finished work.
When previously herein I have said a "suitable box, and mentioned
.

page_text: that it may be made of wrought or cast iron, I do not thereby mean to
confine myself to those materials only for the steelifying box, as there
may be some classes of work or of dimensions of work for which I would
use boxes or containing-chambers made of fire-brick or fire-clay slabs or
similar material, according to the requirements of the class of work to be
done. For certain classes of work I may also employ a repetition or any
number of repetitions of the separating perforated plate and accom-
panying layer of limestone, and of a body of compound with ironwork
imbedded in it enclosed or contained between any two of such plates
and layers. Thus for some classes of work a steelifying box or chamber
may be constructed of dimensions to have placed within it, first, at the
bottom of it a limestone layer with its accompanying perforated plate
above it; next, the superincumbent compound surrounding the iron-
work; and next, the superimposed perforated plate with its limestone
layer above it, thus completing one set, so to speak; the same order of
succession being repeated above that with a following set, and so on.
Or, above and directly upon the second or top limestone layer of the
first set may in certain cases be placed a non-perforated plate forming a
division within the box, and then upon and above the said non-
perforated plate the second or repetition set, as last mentioned, the-said-
non-perforated plate thus dividing that portion of the interior of the box
which is below it into a lower chamber, and that portion which is above
it into an upper or a second chamber, and so on, a similar plato being
interposed between all the other sets in the box or chamber. It should
be borne in mind by the operator that the interposed layers of limestone
would be a longer time, and therefore later, in giving out all their
carbon than those immediately next to the top and bottom sides of
the box or chamber that are next in contact with the fire.
A compact, dense, hard, grey limestone that will not too soon be
calcined, and part with its carbon, must be selected. Or the same
purpose may be served by an analagous native carbonate, by which is
intended a natural mineral, although not strictly a "calcium" oxide,
as, for instance, natural magnesia-carbonate-stone or rock, or the like,
that can upon similar calcination also yield the requisite carbon for the
operation. Discretion also is to be used in proportioning the size of the
broken lumps to the intended length of time of the process. The best
hard limestone is represented by published analyses to contain forty-five
per cent. to fifty per cent. of carbonic acid, and should be preferred.

page_text: I have described flat perforated plates as intended for square boxes
and their work; but other forms may be employed in certain kinds of
work, the object of the plates being in all cases to keep the limestone
separate from the compound. Thus for instance for cylindrical or
tubular work I employ perforated sheet-iron cylinders or tubes to
contain the limestone for the insides, as for instance the inside of
cannon, of pump tubes, or the like, and so on for other applications
as occasion may require, all being alike modifications of this my
Invention.
.
Several persons having considered it incredible that the charcoal
compound could be used repeatedly as described, and upon actually
seeing the process, having found it incomprehensible, as though some
deception were practised, I will here briefly set forth the principle
upon which my process of steelifying iron is based, the method applied,
and its operation according to my Invention.
•
So far as I have ever known, in every previously practised process,
some one or other combination of carbonising and other ingredients have
been employed directly in contact with the iron under the influence of
heat, and the ingredients were more or less consumed and necessarily
required to be replaced at each operation. In the process of my Inven-
tion I apply the principle known in chemistry as "catalysis" by which
term is defined the power with which certain substances are endowed
to awaken and excite by what is called the mere "action of their
presence," the force of affinity between two other bodies to an extent
sufficient to induce and cause their union and combination without
the said substances themselves undergoing any chemical or mechanical
alteration. My method is to surround the iron by a catalytic compound,
which alone I allow to come in contact with the iron, and to provide
a separate source of pure native carbon preserved from all immediate
contact with the iron treated, the whole being so arranged that the iron
shall be at its highest point of affinity for the carbon, at the very time
that the carbon in its nascent (and therefore most eager) state is ready to
be presented to the iron. The operation therefore proceeds as follows:-
The "catalytic" compound surrounding and alone in contact with the
iron under the influence of heat awakens and excites in the wrought
iron a peculiarly active affinity for carbon, the operation being so timed
by the selection and preparation of material as described, that as and

page_text: forated plate or tray or its equivalent (as metallic meshes or the like),
substantially as and for the purpose herein described.
In witness whereof, I, the said Thomas Sheehan, have hereunto
set my hand and seal, this Nineteenth day of March, in tho
year of our Lord One thousand eight hundred and seventy-
four.
THOMAS SHEEHAN. (L.S.)