Improvements in the Manufacture of Armour Plates.
Year: 1892

page_text: Date of Application, 9th Dec., 1892
Complete Specification Left 9th Sept. 1893-Accepted, 14th Oct., 1893
PROVISIONAL SPECIFICATION.
[Communicated from abroad by HAYWARD AUGUSTUS HARVEY, of 445, Main
Street, Orange, New Jersey, United States of America, Mechanical
Engineer.]
Improvements in the Manufacture of Armour Plates.
I, HENRY HARRIS LAKE, of the Firm of Haseltine Lake & Co., Patent
Agents, 45 Southampton Buildings, in the County of Middlesex, do hereby declare
the nature of this invention to be as follows:-
The object of the present invention is to improve the manufacture of the now
well known "Harvey armour plates. A Harvey armour plate as described in
the Specification of former Letters Patent dated 29th September A.D. 1891
No. 16544, is produced by the conversion of a homogeneous low steel armour
plate into a plate which on the side thereof intended to receive the impact of
projectiles has a structure so carburized as to be excessively hard on the surface
and of a gradual inwardly diminishing hardness while the other side or back of
the said plate remains uncarburized this method of treating the plate being termed
decremental carburization.
"
'Harvey'
It has however now been ascertained that in the manufacture of a
plate it is very desirable not only to decrementally carburize the front side of the
plate but also at the same time to decrementally decarburize the back or inner
side thereof.
And the important feature of my present invention is the treatment of the back
of the plate whereby it is as above stated decrementally carburized and softened
simultaneously with the hardening of the front of the said plate.
""
Heretofore in the manufacture of the "Harvey armour plates it has been
necessary during the carburization of the front thereof to apply to the back of the
plate a material or substance that was not capable of giving up carbon to the
surface of the plate with which it is in contact. But according to my present
invention it is not only necessary that such material should not be capable of
giving out carbon but it must be such as will positively absorb carbon, that is to
say it must have a decarburizing action upon the surface of the plate with which it
is in contact.
Assuming the plate to be a low steel armour plate such as Bessemer steel or
open-hearth steel, this plate, having the carbonaceous material packed against its
front face has a mass of decarburizing material packed closely against its back
surface in a suitable heating chamber, and is then heated and maintained at a
high temperature as stated in the said former Specification for a sufficient
length of time to effect the desired results. If the plate is properly packed
with the carburizing and decarburizing materials and the operation is conducted
for a sufficient length of time, the decremental carburization of one side of the
plate and decarburization of the other side of the plate will be effected in such a
manner that the plate will have a gradual increase of carbon from the back to the
front face thereof.
of
may
be
The decarburizing material which I use for the
my invention
purpose
in the form of clay, sand, or the like, but I may use any suitable material which
either naturally or by suitable treatment will be effectual in decarburizing the
back of the plate in the required manner.
T
bo 1900

page_text: COMPLETE SPECIFICATION.
Improvements in the Manufacture of Armour Plates:
1, HENRY HARRIS LAKE, of the Firm of Haseltine Lake & Co., Patent
Agents, 45 Southampton Buildings in the County of Middlesex, 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 :-
1
The object of the present invention is to improve the manufacture of the now
well known " Harvey" armour-plates. A Harvey armour-plate as described in
the Specification of former Letters Patent dated 29th September A.D. 1891
No. 16544 is produced by the conversion of a homogeneous low-steel armour-
plate into a plate which on the side thereof intended to receive the impact of the
projectiles is decrementally carburized and made excessively bard on the surface,
and of a gradually diminishing hardness from the surface inwards.
It is in some cases very desirable not only to decrementally carburize the front
side of the plate but also, at the same time, to decrementally decarburize the back
or inner side thereof.
The important feature of my present invention is the treatment of the back of
the plate whereby it is, as above stated, decrementally decarburized and softened
simultaneously with the decremental carburization and hardening of the front of
the plate.
Heretofore in the manufacture of the "Harvey" armour-plates it has been
customary during the carburization of the front thereof to apply to the back of
the plate a material which is practically inert, that is to say, not capable of
effecting carburization. But according to my present invention it is not only
necessary that such material should not be capable of giving out carbon, but it
must be such as will positively absorb carbon, that is to say, it must have a
decarburizing action upon the surface of the plate with which it is in contact.
Assuming the plate to be an armour-plate of low steel, such as Bessemer steel or
open-hearth steel, this plate, having the carbonaceous material packed against its
front face, has a mass of decarburizing material packed closely against its back
surface in a suitable heating chamber, and is then heated and maintained at a high
temperature, that is to say, a temperature above the melting point of cast iron, for
a sufficient length of time to effect the desired results. If the plate is properly
packed with the carburizing and decarburizing materials and the operation is
conducted for a sufficient length of time the decremental carburization of one side
of the plate and the decremental decarburization of the other side of the plate
will be effected in such a manner that the front face of the plate will be highly
carburized, the carbon gradually diminishing from said face inward toward the
centre of the plate, and the back of the plate will be very slightly if at all
carburized, the carbon gradually increasing from said back inward toward the
centre. The middle stratum of the plate may or may not be of the same degree
of carburization as the original plate, this will depend on the thickness of the
plate or upon the amount of " Harveying" i.e. decremental carburization and
decarburization to which it is subjected according to this invention.
The decarburizing material which I use for the purpose of my invention may be
in the form of clay, sand or the like, but I may use any suitable material which
either naturally or after suitable treatment, will be effectual in decarburizing the
back of the plate in the required manner.
The carburizing and decarburizing material in contact with the faces of the
plates may be arranged to come into contact with such portions of the sides or
edges of the plates as it is desired to effect thereby.

page_text: Having now particularly described and ascertained the nature of the said
invention and in what manner the same is to be performed, as communicated to
me by my foreign correspondent, I declare that what I claim is :-
1. In the manufacture of an armour-plate, the process of decarburizing the
back of the plate simultaneously with the decremental carburization of the front
thereof, substantially as described, for the purpose specified.
2. An armour-plate, manufactured by the process hereinabove set forth.
Dated this 9th day of September 1893.
HASELTINE, LAKE & Co.,
45, Southampton Buildings, London, W.C., Agents for the Applicant.