A New or Improved Process for Improving the Quality of Steel Armour Plates.
Year: 1893

page_text: Date of Application, 28th Feb., 1893
Complete Specification Left, 23rd Nov., 1893-Accepted, 23rd Dec., 1893
PROVISIONAL SPECIFICATION.
A New or Improved Process for Improving the Quality of Steel
Armour Plates.
I, ALFRED LONGSDON, of 75 Old Broad Street in the City of London Civil
Engineer do hereby declare the nature of this invention (a communication to me
from abroad by Louis Grambow of Rixdorf near Berlin in the Empire of
Germany, Merchant) to be as follows:-
The process forming the subject of the present application for Patent, has for
object the improvement of the quality of steel armour plates by subjecting the
same after their manufacture according to one of the known modes of manufacture,
to a series of further metallurgical operations, based on the following phenomena.
If a steel armour plate of any composition, be heated up to a temperature at
which a pasty condition occurs in the arrangement of the molecules, so that they
are rendered capable of a slight re-arrangement, and if they are hardened in this
condition by complete immersion in oil or water or other liquids, the plate will
assume a greater or less degree of hardness, with the formation of an extremely
fine-grained structure. The temperature required for this purpose is higher the
less the amount of carbon contained in the plate, and depends furthermore on
the chemical composition of the plate in other respects.
Now if this plate hardened in this manner be again subjected to a glowing heat
which must however not be so high as the previous hardening heat, and particularly
not so high as to allow of the above mentioned condition of easy movability of the
molecules taking place, and if the plate, as soon as it has uniformly reached with
certainty the temperature corresponding to the said glowing heat, or is maintained
for some hours at such temperature, be allowed to cool slowly again, the hardness
proper of the plate is lost; but the plate retains however a considerably greater
resisting power against shot, than the untreated plate, and acquires above all by the
highly fibrous molecular grain thus produced (which has an appearance on fracture
frequently very similar to velvet with a silky border) the capacity in a very high
degree of offering great resistance to cracking when struck by shot.
If now the plate thus improved, be again heated to the last glowing heat or to a
lower temperature which shall not however exclude hardening, and the plate be
hardened on one face by copious drenching with water or by immersing one face of
the plate in water which may also contain any hardening agents, whilst the other
face of the plate remains out of contact with the water, then an armour plate is
produced having a very hard face intended to be exposed to the action of projectiles,
whilst the mass or main body of the plate has been converted by the preceding
operations into a condition that offers the greatest possible security against cracking
in combination with increased resisting power.
In the case of thinner or harder plates, it may be advantageous, in effecting the
hardening on one face, to protect the other face of the plate that is not to be
hardened, by special means from cooling too quickly; this is effected during the
drenching operation, preferably by placing the plate to be drenched, with its rear side
upon another plate heated to a glowing heat. When the plate is to be immersed
in water, the same object is effected by placing another plate heated to glowing heat
upon the rear face of the plate to be immersed.
The third heating operation may be dispensed with, and the hardening on one
face be effected at the end of the second operation that is to say of the heating for
the formation of the fibrous structure without previously allowing the plate to cool.
As will be seen from the preceding the present process consists in the combination
of the three operations described for the purpose of producing armour plates

page_text: hardened on one face and by means of this process plates are produced which are
equally excellent both with respect to their great resistance against projectiles, and
their small liability to crack.
This new process is most particularly suitable for nickel-steel armour plates of
various degrees of hardness.
This process is however applicable to plates of steel of all kinds, and also to
compound plates of all kinds, which consist only partially of steel, and also to
homogeneous plates the percentage of carbon in which is different on both sides.
Dated this 28th day of February 1893.
BREWER & SON,
London and Leeds, Agents for Applicant.
COMPLETE SPECIFICATION.
A New or Improved Process for Improving the Quality of Steel
Armour Plates.
I, ALFRED LONGSDON, of 75 Old Broad Street, in the City of London, Civil
Engineer, do hereby declare the nature of this invention (a communication from
abroad by Louis Grambow of Rixdorf near Berlin, in the Empire of Germany,
Merchant) and in what manner the same is to be performed to be particularly
described and ascertained in and by the following statement :-
The process forming the subject of the present application for Patent, has for
object the improvement of the quality of steel armour plates by subjecting the
same after their manufacture according to one of the known modes of manufacture,
to a series of further metallurgical operations all as hereafter described.
If a steel armour plate of any composition that is for example nickel-steel,
compound or homogeneous plates, as hereafter stated, be heated up to a temperature
at which a pasty condition occurs in the arrangement of the molecules, so that
they are rendered capable of a slight re-arrangement, and if they are hardened in
this condition by complete immersion in oil or water or other liquids, the plate will
assume a greater or less degree of hardness, with the formation of an extremely
fine-grained structure. The temperature required for this purpose is higher the
less the amount of carbon contained in the plate, and depends furthermore on the
chemical composition of the plate in other respects.
Now if this plate hardened in this manner be again subjected to a glowing heat
which must however not be so high as the previous hardening heat, and particularly
not so high as to allow of the above mentioned condition of easy movability of the
molecules taking place, and if the plate, as soon as it has uniformly reached with
certainty the temperature corresponding to the said glowing heat, or is maintained
for some hours at such temperature, be allowed to cool slowly again, the hardness
proper of the plate is lost; but the plate retains however a considerably greater
resisting power against shot, than the untreated plate, and acquires above all by
the highly fibrous molecular grain thus produced (which has an appearance on
fracture frequently very similar to velvet with a silky border) the capacity in a
very high degree of offering great resistance when struck by shot.
If now the plate thus improved, be again heated to the last glowing heat or to
a lower temperature which shall not however exclude hardening, and the plate be
hardened on one face by copious drenching with water or by immersing one face of
the plate in water which may also contain any known hardening agents, whilst the
other face of the plate remains out of contact with the water, then an armour
plate is produced having a very hard face intended to be exposed to the action of
projectiles whilst the mass or main body of the plate has been converted by the
preceding operations into a condition that offers the greatest possible security
against cracking, in combination with increased resisting power.
In the case of thinner or harder plates, it may be advantageous, in effecting the
hardening on one face, to protect the other face of the plate that is not to be

page_text: hardened, by special means from cooling too quickly; this is effected during the
drenching operation, preferably by placing the plate to be drenched, with its rear
side upon another plate heated to a glowing beat. When the plate is to be
immersed in water, the same object is effected by placing another plate heated to
glowing heat upon the rear face of the plate to be immersed.
The third heating operation may if desired be dispensed with in some cases and
the hardening on one face be effected at the end of the second operation that is to
say of the heating for the formation of the fibrous structure without previously
allowing the plate to cool.
It will be seen from the preceding that the present process substantially consists
in the combination of three operations for the purpose of producing armour plates
hardened on one face, that is to say,
Firstly, hardening the plates by immersing the whole plates in oil, water or
other media, after having previously raised them to a temperature at which the
molecules have acquired the capability of ready re-arrangement.
Secondly, annealing the plates at a temperature which is as high as possible
without however reaching the temperature at which said capability of ready
rearrangement begins.
Thirdly, hardening the plates on one side or face at the same or at a lower
temperature than that specified in No. 2.
By means of this process plates are produced which are equally excellent both
with respect to their great resistance against projectiles, and their small liability to
crack.
This new process is most particularly suitable for nickel-steel armour plates of
various degrees of hardness.
This process is however applicable to plates of steel of all kinds, and also to
compound plates of all kinds, which consist only partially of steel, and also to
homogeneous plates the percentage of carbon in which is different on both sides.
Having now particularly described and ascertained the nature of the said inven-
tion and in what manner the same is to be performed, I declare that what I
claim is :-
First. A process for treating manufactured armour plates consisting in heating
the plates to a temperature at which a pasty condition occurs in the arrangement
of the molecules and hardening the plates by immersement in oil, water, or other
media; then again heating the plates uniformly to a lesser degree than is required
to produce a pasty condition and allowing same to cool slowly; and finally again
heating the plates, to the same as, or to a lower temperature than the second
heating and hardening the said plates on one surface or face by drenching or
immersing the said one face only in water containing or not containing hardening
agents whereby is obtained increased resistance to penetration and decreased
liability to cracking by impact of shot as set forth.
Second. A process for treating manufactured armour plates consisting in heating
the plates to a temperature at which a pasty condition occurs in the arrangement
of the molecules and hardening the plates by immersement in oil, water, or other
media; then again heating the plates uniformly to a lower degree than is required
to produce a pasty condition, and then hardening the said plates on one surface or
face by drenching or immersing the said one face only in water containing or not
containing hardening agents, whereby is obtained increased resistance to penetration
and decreased liability to cracking by impact of shot as set forth.
Third. The new or improved process for improving the quality of steel armour
plates substantially as berein before described.
Dated this 23rd day of November 1893
BREWER & SON,
London and Leeds, Agents for Applicant.