' Improved Manufacture of Projectiles.
Year: 1897

page_text: PROVISIONAL SPECIFICATION.
'
Improved Manufacture of Projectiles.
I, ROBERT ABBOTT HADFIELD, of The Grove. Endcliffe Vale Road, Sheffield,
in the County of York, Steel Manufacturer, do hereby declare the nature of
this invention to be as follows:--
This invention has reference to the manufacture of projectiles possessing great
strength and penetrative powers and specially suitable for armour piercing and
like purposes. For this purpose the projectiles are made of an alloy of iron,
carbon, chromium and nickel, containing also silicon or aluminium
silicon and aluminium as I will now proceed to more fully explain.
or both
A suitable basis of iron for making the alloy from which my improved pro-
jectiles are subsequently cast, as hereinafter described, is decarbonized iron pro-
duced by any suitable steel making process and as free as possible from man-
ganese. The carbon, chromium, nickel, silicon, and aluminium may be added
in various forms. Thus for example, the carbon may be in the form of a suitable
carbonaceous material such for example as white iron of good pure quality low
in sulphur and phosphorous and practically free from manganese. The chromium
and nickel may be added in the metallic form, or in the form of ferro-chromium
and ferro-nickel respectively. The aluminium may be added in the metallic
state or in the form of ferro-aluminium and the silicon in the form of ferro-
silicon. The aluminium or silicon, or hoth, is or are added for the purpose of
obtaining soundness in the alloy and freedom from blow holes. The carbon-
aceous material and chromium and nickel alloys, and also the aluminium and
silicon alloys should be added in a melted state to the molten iron so as to
facilitate thorough admixture therewith.
I have obtained satisfactory results in practice when using say about 0.75%
(decimal seven five per cent.) to 1% (one per cent.) of carbon; 2% (two per cent.)
of chromium and 2% (two per cent.) of nickel. care being taken to keep the
amount of manganese that may be present at least under 0.3% (decimal three
per cent) but preferably as much lower as possible as I have found that the
presence of manganese much in excess of that mentioned causes water cracking
when the projectiles made of my alloy are hardened. The percentages of carbon,
chromium and nickel may be varied to some extent from those mentioned pro-
vided the resulting steel is free from or low in manganese and that it is capable
of being readily hardened in the mass, that is to say, practically throughout the
cross section of the projectiles to be subsequently made therefrom. Thus the
carbon might vary from 060 % (decimal six per cent.) to 15% (one decimal
five per cent.): the chromium from 0.70% (decimal seven per cent.) to 3%
(three per cent.); and the nickel from 050 % (decimal five per cent.) to 35%
(three decimal five per cent.). I have however obtained the best results with the
proportions first hereinabove mentioned, manganese being practically absent. The
silicon may vary say up to 25% (two decimal five per cent.) though preferably
for most purposes not more than 030 % (decimal three per cent.) need be used.
The aluminium may vary say up to 1% (one per cent.) but preferably for most

page_text: purposes not more than 0.10% (decimal one per cent.) will be necessary. Also
tungsten may be present say up to 1% (one per cent.), without injuriously affect-
ing the hardening qualities of the steel.
In carrying out my invention I take iron such for example as is now used in
the production of acid steel and decarbonize it preferably by the pneumatic method
in a suitable vessel or converter, but it may be by treatment in the ordinary way
in an open hearth furnace, care being taken in either case to eliminate practically
the whole of the carbon, manganese and silicon it may contain. To the molten
iron thus obtained I add the carbonizing physic, chromium and nickel as above
described and also the aluminium or silicon, or both aluminium and silicon. It
is important in order to obtain a satisfactory result that the various additions
should not be made to the molten iron whilst the same is in the converting
vessel or furnace because by adopting this method it is difficult to ensure that
the resulting steel shall contain the desired exact proportions of the added
substances and shall be of uniform quality. To obviate this difficulty I prefer to
run successively into a ladle or vessel carried by a suitable weighing machine, such
as Denison weighing machine, or platform weighing machine, the
desired amounts of carbonizing physic, chromium, nickel and aluminium
silicon
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or aluminium and silicon each in suitable form such
as hereinbefore described and in a molten condition, the desired
weights of the several substances (preferably previously melted in crucibles)
being ascertained in a ready and exact manner by means of the weighing machine.
Into the weighed contents of the ladle whilst the latter is carried by the weighing
machine there is then run, preferably direct from the furnace, so much of the
molten iron as will increase the weight of the contents of the ladle to that of
the required quantity of my special alloy.
or
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From the alloy thus obtained projectiles are made by casting for which pur-
pose the steel is run off from the ladle into moulds which may he made in the
ordinary manner of sand or metal and provided with suitable cores when the pro-
jectiles are to be formed with a bursting chamber. For solid
jectiles or shot. the cores are of course omitted. The projectiles may be
cast point upward or base upward. After removal from the mould each pro-
jectile is preferably annealed by heating it to a suitable annealing temperature
say about 1600° F. in a furnace and then allow it to cool slowly. The sinking or
feeding head is cut off from the casting in any convenient manner and any
necessary machining of the projectile carried out.
The projectile thus cast and finished to shape is hardened, preferably at its
point and shoulder portions. For this purpose these portions are healed to a
suitable temperature say from about 1500° F. to 1700° F. and then quickly
dinned point downward into cooling medium such as oil or water, or a mixture of
the two. at the ordinary temperature, cooling medium, such as that indicated.
being simultaneously circulated in contact with the forward interior portion of
the projectile in the ease of its having a bursting chamber.
.
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1004

page_text: this invention and in what manner the same is to be performed to be particu-
larly described and ascertained in and by the following statement:-
-
This invention has reference to the manufacture, at a comparatively low cost,
of cast projectiles possessing great strength and penetrative powers and specially
suitable for armour piercing and like purposes. For this purpose the projectiles
are made of hard steel of superior quality and consisting of an alloy of iron,
carbon, chromium and nickel, containing also silicon or aluminium or both
silicon and aluminium as I will now proceed to more fully explain.
A suitable basis of iron for making the steel or alloy (hereinafter called steel)
from which my improved projectiles are subsequently east, 19 hereinafter
described, is decarbonized iron produced by any suitable steel making process
and as free as possible from manganese. The carbon, chromium, nickel, silicon,
and aluminium may be added in various forms. Thus for example, the carbon
may be in the form of a suitable carbonaceous material such for example_as
white iron of good pure quality, low in sulphur and phosphorus and practically
free from manganese. The chromium and nickel may be added in the metallic
form, or in the form of ferro-chromium and ferro-nickel respectively. The
aluminium may be added in the metallic state or in the form of
ferro-aluminium and the silicon in the form of. ferro-silicon. The
aluminium or silicon, or both, which constitute a solidifying agent or agents, is
or are added for the purpose of obtaining soundness in the alloy and freedom
from blow holes. The carbonaceous material and chromium and nickel alloys,
and also the aluminium and silicon alloys should be added in a melted state
to the molten iron so as to facilitate thorough admixture therewith.
I have obtained satisfactory results in practice when using say about 075 %
(decimal seven five per cent.) to 1% (one per cent.) of carbon: 2% (two per cent.)
of chromium and 2% (two per cent.) of nickel, care being taken to keep the
amount of manganese that may be present at least under 038% (decimal three
per cent) but preferably as much lower as possible as I have found that the
presence of manganese much in excess of that mentioned causes water cracking
when the projectiles made of my steel are hardened. The percentages of carbon,
chromium and nickel may be varied to some extent from those mentioned pro-
vided the resulting steel is free from or low in manganese and that it is capable
of being readily hardened in the mass, that is to say, practically throughout the
cross section of the projectiles to be subsequently made therefrom. Thus the
carbon might vary from 06% (decimal six per cent.) to 15% (one decimal five
per cent.): the chromium from 07% (decimal seven per cent.) to 3% (three
per cent) and the nickel from 05 % (decimal five per cent.) to 35% (three
decimal five per cent.). I have however obtained the best results with the pro-
portions first hereinabove mentioned, manganese being practically absent in the
resultant product. The silicon may vary say up to 25% (two decimal five
per cent.) though preferably for most purposes not more than 0.3% (decimal
three per cent.) need be used. The aluminium may vary say up to 1% (one
per cent.) but preferably for most purposes not more than 01% (decimal one
per cent.) will be necessary. Also tungsten may be present say up to 1%
(one per cent.), without injuriously affecting the hardening qualities of the steel.
In carrying out my invention I take in such for example as is now used
in the production of acid steel and decarbonize it preferably by the pneumatic
method in a suitable vessel or converter, but it may be by treatment in the
ordinary way in an open hearth furnace, care being taken in either case to
eliminate practically the whole of the carbon, manganese and silicon it may
contain. The various basic or semi-basic processes now in use may also he
employed for producing the iron required to form the base for my physic additions.
To the molten iron thus obtained I add the carbonizing physic, chromium and
nickel as above described and also the aluminium or silicon, or both aluminium
and silicon.

page_text: The manner of making these additions is of the greatest importance in pro-
ducing steel of special high quality, and I proceed as follows, viz. the physics
are melted in crucibles or in a furnace which is not subject to oxidising influence,
and the molten physic is run into a ladle. For example, a furnace may be
used with a basic lining, such as dolomite or magnesite or magnesia, or mixtures
of these, in which the constituent elements of the alloy are not oxidized.
Upon the physic the decarbonized iron is then poured.
The addition of the physic in the furnace itself is objectionable because oxidis-
ing influences are at once at work, and consequently steel of such uniformity as
I produce cannot be obtained.
It is extremely important in order to obtain a satisfactory result that the
various additions should not be made to the molten iron whilst the same is in
the converting vessel or furnace because by adopting this method it is difficult
to ensure that the resulting steel shall contain the desired exact proportions of
the added substances and shall be of uniform quality. To obviate this difficulty
I prefer to run successively into a laille or vessel carried by a suitable weighing
machine, such as a Denison weighing machine, or a platform weighing machine,
the desired amounts of carbonizing physic, chromium, nickel and aluminium or
silicon, or aluminium and silicon, caeli in a suitable form such as hereinbefore
described and in a molten condition, the desired weights of the several substances
(preferably previously melted in crucibles) being ascertained in a ready and exact
manner by means of the weighing machine. Into the weighed molten contents
of the ladle, whilst the latter is carried by the weighing machine, is then run,
preferably direct from the furnace, so much of the molten iron as will increase
the weight of the contents of the ladle to that of the required quantity of my
special steel.
1 have found the commonly accepted idea that manganese is necessary in steel
is to a large extent erroneous, and in fact its presence is in many ways deleterious.
In making special high quality steel, that is, hard steels containing say 07%
(decimal seven per cent.) to 11 (one decimal one per cent.) of carbon, I find
that the lower the manganese is kept the better the product, but when the
material is not required to possess natural hardness, or capacity for subsequent
hardening, the advantage to be gained is not so great. as I believe that only
in the presence of carbon is the manganese harmful.
In other words, manganese may not be objectionable in mild steels say under
about 85% (decimal three five per cent.) carbon, because in such cases and
they probably represent the majority of uses for which steel is required, the
action of the carbon is so much weakened that more or less manganese is
immaterial.
Manganese is in itself a very hard and brittle metal and while this in itself
may not be an objection, yet I consider that in its action as a carbide of man-
ganese when carbon is present, it is most harmful where the special qualities of
hardness and toughness are requisite, as in the production of projectiles, believing
that these qualities cannot be developed if manganese is present in quantity say
over 25% (decimal two five per cent.) to 03% (decimal three per cent.).
It is to be borne in mind, however, that I am not referring to large percentages,
such as in my manganese steel alloys, containing from 20% (two per cent.) up
to 2000% (twenty per cent.) manganese, and which come under an entirely
different category.
Hitherto, so far as I am aware, it has not been known that sound ingots, that
is to say, free from less sound portions and also free from cracks or other deferts,
or sound billets or forgings, could he obtained without the presence of manganese,
particularly if silicon or aluminium or both, be used, but as herein before set
forth I have discovered this fact, and that with sufficient silicon or aluminium,
or both, no manganese is required while the resultant product can be rolled and
forged or cast like other hard steels, and readily hardened and tempered with
the cracking not only no more, but actually less than with the expensive crucible
steels.

page_text: I find that with practically no manganese, the steel, while hardening equally
well as heretofore, is much tougher and shows a better looking fracture, all of
which goes to show that the absence of manganese has prevented the formation
of the very objectionable brittle carbide of manganese.
Furthermore I have found that by eliminating the manganese in my improved
steel or keeping it low in quantity as set forth, it is not necessary to employ
high quality stuck or raw material for the production of such steel. Thus whilst
it has heretofore been necessary in the production of armour piercing projectiles
of hard steel to employ the very highest quality of raw material, such as
Swedish pig or melting iron, I find that by making the steel free from or low
in manganese as set forth, the steel may be allowed to contain a larger proportion
of sulphur and phosphorus than would otherwise be admissible, consequently L
am able to use in the production of my projectiles cheap raw stock such as
ordinary hematite pig iron, or even mixtures of ordinary pig iron and steel scrap.
Thus, whereas high quality raw material containing sulphur and phosphorus
only say up to about 002 % (decimal naught two per cent.) each has heretofore
been necessary for producing hard steel for use in the manufacture of projectiles,
by keeping the manganese in the steel low in quantity as set forth, the sulphur
and phosphorus in the raw material may without serious disadvantage be allowed
to reach say about 005 % (decimal naught five per cent.) or 0.06% (decimal
naught six per cent.) thus rendering available a much wider range of raw
material of comparatively small cost for the production of armour piercing shells.
Such a basis of iron must of course be decarbonized, demanganized and
desiliconized as hereinbefore described before mixing the carbon, chromium and
nickel therewith, sufficient silicon or aluminium, or silicon and aluminium
being also added to decompose any oxide there may be present. This latter
addition is important because there will be little or no manganeze present for
effecting such decomposition.
From the steel thus obtained projectiles are made by casting for which purpose
the steel is run off from the ladle into moulds which may be made in the ordinary
manner of sand or metal and provided with suitable cores when the projectiles
are to be formed with a bursting chamber. In this case I sometimes cast the
shells in moulds point downward and, in order to prevent settling or falling
away from the core, I use a core formed of sand or composition but having at
its point a cast iron, steel or other metal tip which chills or sets the steel forming
the adjacent portion of the shell more quickly. By this means a projectile is
obtained practically free from settling or shrinkage cavities thereby considerably
reducing the risk of cracks resulting from the hardening process. The construc-
tion of the mould employed is varied according to the shell to be produced. Thus
if the head of the shell is to be thick and the walls thin, the head portion or the
mould is made of iron so as to rapidly chill the steel therein, whilst the body
portion is of sand so that the wall part of the shell remains fluid and feeds metal
to the head part as it sets. If the walls and head are to be of fairly uniform thick-
ness the shell may be cast entirely in an iron mould or chill. To facilitate the
production of sound shells, the steel is run into the mould in a tangential direc-
tion so as to cause it to spin around the core therein and enable slag to readily
separate. For solid projectiles or shot, the cores are of course omitted. After
removal from the mould, each projectile is preferably annealed by heating it
to a suitable annealing temperature say about 1600° F. in a furnace and then
allowing it to cool slowly. The sinking or feeding head is cut off from the cast-
ing in any convenient manner and any necessary machining of the outside of the
cast projectile, for finishing it to the required dimensions, carried out.
The projectile thus cast and finished to shape is hardened, preferably at its
point and shoulder portions. For this purpose these portions are heated to a
suitable temperature say from about 1500° F. to 1700° F. and then quickly dipped
point downward into a cooling medium such as oil or water, or a mixture of the
two, at the ordinary temperature, cooling medium, such as that indicated, being

page_text: simultaneously circulated in contact with the forward interior portion of the
projectile in the case of its having a bursting chamber. The hardening of the
projectile may advantageously be effected in the manner and by the means
described in the Specification of another Application for Letters Patent filed by
me dated February 12th 1898, No. 3548, but such method and means are not
herein claimed as forming part of my present invention.
Having now particularly described and ascertained the nature of the said
invention and in what manner the same is to be performed 1 declare that what
I claim is:-
1. The improved manufacture of projectiles substantially as herein described.
namely by casting an alloy composed of iron, carbon, chromium, nickel sub-
stantially in or about the proportions mentioned with silicon or aluminium or
silicon and aluminium and free from or low in manganese in moulds of the
desired shape and size, and hardening the cast projectiles as set forth.
2. The manufacture of cast projectiles in the improved mauner herein set forth
using as a basis iron decarbonized, demanganized and desiliconized by the
pneumatic method or by the open hearth method, mixing such iron with carbon-
izing physic, chromium, nickel and a solidifying agent in suitable form and
substantially in or about the proportions set forth, in a ladle or vessel that is
adapted by suitable weighing mechanism to show the weight of its contents,
the iron and the other substances being added in a molten state and separately
and successively so that the weight of each and consequently the proportion
thereof can be easily controlled, running the resulting alloy from the ladle or
vessel into moulds to form cast projectiles of approximately the desired shape,
annealing the cast projectiles, machining them to the finished shape and hardening
them, as set forth."
3. A hardened cast armour piercing projectile composed of chromium-nickel
steel tree from or low in manganese and including a solidifying agent as set
forth.
4. Cast projectiles composed of an alloy of iron, carbon, chromium and nickel
substantially in or about the proportion's first herein set forth with silicon or
aluminium or silicon and aluminium and little or no manganese, substantially
as described.