AN IMPROVED MODE OF MANUFACTURING ARMOUR DrATES
Year: 1877

page_text: LETTERS PATENT to Alexander Wilson, of Sheffield, in the County of York,
for the Invention of "AN IMPROVED MODE OF MANUFACTURING ARMOUR
DrATES"
Sealed the 8th September 1877, and dated the 14th March 1877.
PROVISIONAL SPECIFICATION left by the said Alexander Wilson at the Office
of the Commissioners of Patents on the 14th March 1877.
.
ALEXANDER WILSON, of Sheffield, in the County of York. "AN IMPROVED MODE
OF MANUFACTURING ARMOUR PLATES."
"
The object of this Invention is so to treat armour plates made of wrought or cast
steel in any well known or approved manner that the character of the metal to a
given depth of the plate will be changed, the hardness and brittleness of the steel
being replaced by toughness and malleability, whereby the plate will present a
combination of resisting forces the best calculated to ensure its impenetrability to
shot and shell. Supposing, for example, it be desired to give the plate a soft or
toughened back, and to retain the natural hardness of the steel at the face of the
plate, the hard face serving to prevent penetration, and the soft back the starring or
breaking away of the hard face, I proceed in the following manner :-I take a plate
of steel, say 20 inches thick and of any desired length and breadth, which may have
been either "cast or "wrought," and containing any desired proportion of carbon,
and I proceed to decarbonize the plate to a depth of about 8 inches more or less, .
leaving the remaining 12 inches unchanged. Having provided a cast-iron box,
I cover the bottom of the same with a layer of charcoal, and on this charcoal I place
the steel plate, which has previously been coated with black lead or "graphite
its under side and up its edges to a height of 12 inches, or the depth at which
I intend to retain the plate unchanged. I then fill the space between the edges of
the plate and the inside of the box with gannister, to the height of 12 inches,
and to the upper part of the plate, both on its face and at its edges, I apply "oxide
of iron "
or other decarbonizing agent. I then place a cover on the box, and having
luted it I run the same into an annealing oven, suitably constructed to receive about
four or more of such boxes when the oven is charged, and the entrance to the oven
is then built up with fire-bricks. I heat the oven by means of coal fires, and
Prins G71
on

page_text: maintain the temperature for a sufficient length of time until the decarbonization of
the upper 8 inches effected. The oven is now allowed to cool down gradually,
the boxes with their plates are then withdrawn, the plates taken out and tooled on
their edges and ends to the required dimensions. By this treatment it will be found
that the protected portion of the plate, or that part which was covered by graphite,
will retain its hardness, while the portion exposed to the oxide of iron will have
acquired the toughness desired.
It will be readily understood that both faces of the plate can if desired be decar-
bonized, and that to any given depth, while the central portion of the plate retains
its hard character.
SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Alexander Wilson in the Great Seal Patent Office on the 13th September
1.877.
ALEXANDER WILSON, of Sheffield, in the County of York. "AN IMPROVED MODE
OF MANUFACTURING ARMOUR PLATES."
The object of this Invention is so to treat armour plates made of wrought or cast
steel in any well known or approved manner that the character of the metal to a
given depth of the plate will be changed, the hardness and brittleness of the steel
being replaced by toughness and malleability, whereby the plate will present a
combination of resisting forces the best calculated to ensure its impenetrability to
shot and shell. Supposing, for example, it be desired to give the plate a soft or
toughened back, and to retain the natural hardness of the steel at the face of the
plate, the hard face serving to prevent penetration, and the soft back the starring or
breaking away of the hard face, I proceed in the following manner: -I take a plate
of steel, say twenty inches thick and of any desired length and breadth, which may
have been either "cast" or "wrought," and containing any desired proportion of
carbon, and I proceed to decarbonize the plate to a depth of about eight inches more
or less, leaving the remaining twelve inches unchanged. Having provided a cast-
iron box I cover the bottom of the same with a layer of charcoal, and on this charcoal I
place the steel plate, which has previously been coated with black lead or "graphite"
on its under side and up its edges to a height of twelve inches, or the depth at
which I intend to retain the plate unchanged. I then fill the space between the
edges of the plate and the inside of the box with ganister to the height of twelve
inches, and to the upper part of the plate, both on its face and at its edges, I apply
"oxide of iron or other decarbonizing agent. I then place a cover on the box,
and having luted it I run the same into an annealing oven, suitably constructed to
receive about four or more of such boxes. When the oven is charged, and the
entrance to the oven is built up with fire-bricks, I heat the oven by means of coal
fires, and maintain the temperature for a sufficient length of time until the decar-
bonization of the upper eight inches is effected. The oven is then allowed to cool
down gradually, and the boxes with their plates. are withdrawn.
"
In the accompanying drawing Fig. 1 shows in sectional elevation an oven suitable
for treating armour plates according to this Invention; and Fig. 2 is a sectional plan
of the same taken at the levels indicated by the line 1, 2, of Fig. 1.
The oven is built up of fire-brick, and is provided with fire-places A, A, at its
opposite ends. The heat from these fire-places is reverberated by an arched roof B
into the central space of the oven, in which are placed the boxes containing the
armour plates to be annealed. Below the floor of the oven are serpentine flues C, C,
which communicate with the central space of the oven by openings c, and lead off to
the chimney D. By this arrangement a proper circulation of the heated gases is
kept up in the oven, and the gases are caused to yield up the greater portion of their
beat before escaping from the oven. E, E, are cast-iron boxes, in which the armour

page_text: plates to be treated aro placed as above explained. When the armour plates are
properly packed in these boxes, and the covers are applied thereto, they are set up
one above another, as shown in the Drawing, fire-brick supports being interposed
between the lowermost box and the floor of the oven, and also between the upper
and lower boxes.
The oven when charged with armour plates properly packed in boxes, as above
explained, is heated to a temperature ranging from, say, one thousand five hundred
to two thousand degrees of Fahrenheit, and it is maintained at such heat for a
length of time, varying according to the thickness of the armour plates under
treatment.
For plates say twenty inches in thickness, I maintain the heat of the oven for
some ten days more or less, and then allow it to cool down gradually.
When sufficiently cool I remove the fire-brick filling from the opening, draw out
the boxes from the oven, uncover the plates, lift them out of the boxes, and tool
their edges, to bring them to the required shape or dimensions. By this treatment
it will be found that the protected portion of the plate, or that part which was
covered by graphite, will retain its hardness, while the portion exposed to the oxido
of iron will have acquired the toughness desired.
It will be readily understood that both faces of the plate can if required be
decarbonized, and that to any given depth, while the central portion of the plate
retains its hard character.
Having now set forth the nature of my Invention of "An Improved Mode of
Manufacturing Armour Plates," and explained the manner of carrying the same into
effect, I wish it to be understood that under the above in part recited Letters Patent
I claim, imparting to armour plates, whether made of wrought or cast steel, a
partial toughness (on one or both faces), in the manner and for the purpose above
described.
In witness whereof, I, the said Alexander Wilson, have hereunto set my hand
and seal the Sixth day of September in the vear of our Lord One thousand
ALEX. WILSON. (L.S.)`