Improvements in the Manufacture of Armour Plates.
Year: 1891

page_text: The decision of the Comptroller-General, of the 25th day of March 1893, allowed,
under Section 18 of the Patents, &c. Act, 1883, an Amendment of this
Specification.
Date of Application, 31st Mar., 1891
Complete Specification Left, 18th Dec., 1891-Accepted, 30th Jan., 1892
PROVISIONAL SPECIFICATION.
Improvements in the Manufacture of Armour Plates.
I, TOLMIE JOHN TRESIDDER, Captain, late of H.M. Royal Engineers, now of
the Atlas Steel Works, Sheffield, in the County of Yorkshire, do hereby declare
the nature of this invention to be as follows:-
In development of the process for which Patent No. 12347 was granted to me
on the 12th Sep. 1887 & with the view of hardening the face of an armour plate
or of improving its molecular structure throughout, I heat it & then chill one or
both of its surfaces with water, oil or other suitable fluid, projected against it
under pressure from a large number of small apertures placed close together in an
apparatus constructed for the purpose. I have found by actual experiment on a
large scale that plates treated with water in this way are superior as regards
resistance to projectiles to untreated plates or to plates quenched with oil in the
ordinary manner. The treatment may or may not be followed by annealing or
tempering according to the degree of hardness required.
Dated this 26th day of March 1801
T. J. TRESIDDER.
COMPLETE SPECIFICATION (AMENDED).
Improvements in the Manufacture of Armour Plates.
I, TOLMIE JOHN TRESIDDER, Captain, late of H.M. Royal Engineers, now of
the Atlas Steel Works, Sheffield, in the County of Yorkshire, 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:-
In development of the process for which Patent No. 12347 was granted to me
on the 12th September 1887 and with the view of hardening the face of an armour
plate or of improving its molecular structure throughout, I heat it and then chill
one or both of its surfaces with water, oil or other suitable fluid, projected against
it under pressure from a large number of small apertures placed close together in
an apparatus constructed for the purpose. I have found by actual experiment on
a large scale that plates treated with water in this way are superior as regards
resistance to projectiles to untreated plates or to plates quenched with oil in the
ordinary manner. The treatment may or may not be followed by annealing or
tempering according to the degree of hardness required.
This invention is suggested by the theory that the unsatisfactory action of a
water-bath in hardening pieces of steel of large bulk is due principally to the
formation of a steam envelope round the immersed article, which envelope being
continually broken and reformed during the early stages of quenching only allows
the heat to be abstracted spasmodically instead of with the uniformity which is the
first requisite for a successful result; that the superior action of an oil-bath is due
not to the chemical composition of oil but to the absence of this steam envelope;
Price 3

page_text: and that the improvement in the action of a water-bath due to the addition thereto
of glycerine or of any substance tending to raise the boiling point is to be
explained in the same way.
The object of this invention therefore is to so apply water in quenching steel
that the formation of a steam envelope shall be impossible; but I do not limit
myself to the use of water alone as my 'process has the contingent advantage of
allowing any fluid gas or vapour to be uniformly applied to one side only of an
armour plate or similar article which would not be possible by immersion in a
bath unless the surface to be treated happened to be perfectly flat.
By this invention I obtain (1) intense hardness and tenacity in the faces of com-
pound armour plates (steel faced with iron backs), (2) intense hardness and tenacity
in the faces of compound steel armour plates (all steel with or without nickel &c. with
high carbon faces and mild backs whether built up, or made originally homogeneous
and subsequently "converted" on one side) and (3) increased tenacity and toughness,
such as has hitherto been obtained by oil-hardening followed by annealing, in
homogeneous steel armour plates whether containing chrome, nickel or other such
ingredients or not. The injurious and commonly fatal internal strains induced in
a large mass of steel by quenching it in a water bath are entirely avoided by my
process, which at the same time retains all the valuable properties inherent to
water quenching.
The apparatus which I employ in carrying out my invention consists of a
gridiron of parallel pipes with a surface as large as or larger than the armour
plate to be treated.
The pipes may be three quarters of an inch in diameter and spaced at a distance
from centre to centre of say one and a half inches.
Along each pipe is a row of perforations by which jets of water may issue. The
perforations may be say one inch apart and one eighth of an inch in diameter, and
should be drilled with a little obliquity alternately to right and left to better
distribute the cooling medium.
The pipes are connected with a suitable source by which, whilst they are in use,
water under a high pressure preferably not less that 80 lbs. to the square inch is
supplied to them. The number, size and arrangement of the supply pipes is such
that the pressure may reach all the jets with great uniformity.
The armour plate suitably heated in accordance with the quality of the metal is
supported in a horizontal position parallel to the face of the gridiron and at a few
inches distance below it.
The water is then turned on and the high pressure of the jets causes the water
to be brought into contact with the surface of the armour plate without assuming
the spheroidal state, while their uniform distribution insures an absolutely uniform
chilling, a result never heretofore attained.
When it is desired to chill both faces of the plate, two similar gridirons are
employed; they are set parallel the one to the other and equidistant from the
armour plate which is between them.
I attach much importance to the horizontal position of the armour plate during
treatment and the downward vertical action of the douche, for if the douche acted
upwards, only the actual points on which the jets impinged would be chilled, and if
the plate were placed vertically or sloping the flow over its surface would be
greater at one part than another. In either case there would be interference with
that complete synchronous uniformity of treatment of every part of the surface
which it is my great object to attain.
In place of water other fluids both liquid and æreform are sometimes employed.
The action of the water douche on high carbon steels is, as might be expected,
to produce intense hardness. As the carbon is lower the hardening becomes less
marked, but an appreciable hardening or stiffening effect is produced with steels
containing as little as two tenths of one per cent. of carbon. In such a case the
effect of the treatment resembles that obtained by hardening a steel of somewhat
higher carbon in oil at say 1600° F. and then annealing at say 900° F. The wet

page_text: air has a milder action (on large masses) about that of oil-hardening at 1300° F.
and annealing at 1200° F. Dry air, especially hot dry air, has the mildest effect
of all, but the uniform distribution of the cooling action peculiar to this invention
always results in improving the steel.
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 :-
The treatment of armour plates substantially in the manner described that is
to say by submitting the plate whilst in a heated state to the equable chilling of
one or both of its faces by very numerous small jets of water or other suitable fluid
projected at high pressure and simultaneously against the whole area of the face or
faces of the armour plate as herein set forth.
2. In-the-manufacture of armour plates the use-substantially as described of a
spray or douche of wet or dry air or other gas or vapour, for the purpose of
effecting such beneficial changes in the material as have hitherto been aimed at by
quenching in oil and annealing, quenching in lead and annealing and kindred
processes.
3. The use in the treatment of armour plates of apparatus substantially-as
described.
1
CD11001
T. J. TRESIDDER.