Improved Manufacture of Steel.
Year: 1897

page_text: Improved Manufacture of Steel.
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 hard steel having special
susceptibility to hardening with less liability to water cracking than usual, and
specially suitable for use in the production of articles of comparatively large
sectional area, that require to be hardened in the mass, that is to say, practically
throughout their section.
For this purpose 1 add to a suitable basis of iron, say about 0.75% (decimal
seven five per cent.) to 1% (one per cent.) of carbon, 2% (two per cent.) of chrom-
ium, and 2% (two per cent.) of nickel, care being taken to keep the amount of
manganese that may be present at least under 03% (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
steel is hardened. The percentages of carbon, chromium and nickel may be varied
to some extent from those mentioned provided the resulting steel is nearly free
from or low in manganese and that it is capable of being readily hardened. Thus
the carbon might vary from 0-60% (decimal six per cent.) up to 175% (one
decimal seven five per cent.); the chromium might vary from about 025% (decimal
two five per cent.) up to 5% (five per cent.), and the nickel from about 0.25%
(decimal two five per cent.) up to 7 (seven per cent.). I have however obtained
the best results for articles of comparatively large mass, with the proportions
first herein-above mentioned, manganese being practically absent. Silicon or
aluminium, or both is or are also added to the molten steel for the purpose of obtaining
soundness and freedom from blow holes. The silicon may vary say up to 25%
(two decimal live per cent.) though preferably for most purposes smaller quantities
say of about 030% (decimal three per cent.) are sufficient. The aluminium may
vary say up to about 02% (decimal two per cent.) but preferably for most purposes
Dot more than 0.10% (decimal one per cent.), will be necessary.
A suitable basis of iron for making my improved steel is decarbonized iron pro-
duced 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 carbonaceous material and chromium and nickel alloys and also the alu-
minium and silicon alloys should be added in a melted state to the molten iron
So as to facilitate thorough admixture therewith.

page_text: 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 elimin-
ate practically the whole of the carbon, manganese and silicon it may contain
Το 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 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, each in a
suitable form such as herein before 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 steel which is then either run off into ingots
that can afterwards be forged into articles of any desired shape, or is poured into
moulds to produce castings.
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 and in what manner the same is to be performed to be particularly
described and ascertained in and by the following statement:
—
This invention has reference to the manufacture of hard steel having special
susceptibility to hardening with less liability to water cracking than usual, and
specially suitable for use in the production of articles of comparatively large
sectional area, that require to be hardened in the mass, that is to say, practically
throughout their section.
For this purpose I add to a suitable basis of iron, say about 0'75% (decimal
seven five per cent.) to 1% (one per cent.) of carbon, 2% (two per cent.) of chrom-
ium, and 2% (two per cent.) of nickel, care being taken to keep the amount of
manganese that may be present at least under about 02% (decimal two 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
steel is hardened. For this reason I regard manganese as a deleterious substance

page_text: in hard steel and one the presence of which should therefore be avoided as far
as possible. The percentages of carbon, chromium and nickel may be varied
to some extent from those mentioned provided the resulting steel is nearly free
from or low in manganese and that it is capable of being readily hardened. Thus
he carbon might vary from 06% (decimal six per cent.) up to 175% (une
decimal seven five per cent.); the chromium might vary from about 025 % (decimal
two five per cent.) up to 5% (five per cent.), and the nickel from about 0.25%
(decimal two five per cent.) up to 7% (seven per cent.). I have however obtained
the best results for articles of comparatively large mass, with the proportions
first herein-above mentioned, manganese being practically absent. Silicon or
aluminium, or both is or are also added to the molten steel for the purpose of obtaining
soundness and freedom from blow holes. The silicon may vary say up to 25%
(two decimal five per cent.) though preferably for most purposes smaller quantities
say of about 03% (decimal three per cent.) are sufficient. The aluminium may
vary say up to about 02% (decimal two per cent.) but preferably for most purposes
not more than 0.1% (decimal one per cent.) will be necessary.
A suitable basis of iron for making my improved steel is decarbonized iron pro-
duced 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 carbonaceous material and chromium and nickel alloys and also the alu-
minium and silicon alloys should be added in a melted state to the molten iron
so as to facilitate thorough admixture therewith.
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 each 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 be employed for pro-
ducing 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.
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 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, each in a
suitable form such as herein before 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 steel which is then either run off into ingots
that can afterwards be forged into articles of any desired shape, or is poured into
moulds to produce castings.
I 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.

page_text: 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 05% (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 manganese
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 200% (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 defects,
could be obtained without the presence of manganese, particularly if silicon or
aluminium, or both, he used, but as hereinbefore 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.
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 stock or raw material for the production of my special alloy or improved
steel. Thus whilst it has heretofore been necessary in the production of hard
steel of good quality, to employ the very highest quality of raw material, such
as Swedish pig or melting iron, I find that in producing steel according to this
invention, in which the manganese is kept low, hard steel of superior quality
can be produced containing a larger proportion of sulphur and phosphorus than
would be admissible if manganese was present in much larger quantity, cou-
sequently I am able to use cheap raw stock such as ordinary hematite pig iron,
or even mixtures of ordinary pig iron and steel scrap, to form a suitable basis of
iron for forming my improved steel. Thus, whereas high quality raw material
containing sulphur and phosphorus only say up to about 002% (decimal nought
two per cent) each has heretofore been necessary for producing hard steel, 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, especially
when the steel is to be used for castings, be allowed to reach say about 005"
(decimal nought five per cent.) or 106% (decimal nought six per cent.) thus
rendering available a much wider range of raw material of comparatively small
cost for the production of high quality steel. Such a basis of iron must of course
he decarbonized, demanganized and desiliconized as hereinbefore described
before mixing the carbon, chromium and nickel therewith, sufficient silicon or
aluminium, or both, being also added to decompose any oxide there may be
present. This latter addition is important because there will be little or no
manganese present for effecting such decomposition.

page_text: Having now particularly described and ascertained the nature of the said inven-
tion and in what manner the same is to be performed I desire to have it understood
that I do not intend to claim as of my present invention anything claimed in
the Specification of my previous Patent No. 13847 of 1893 but declare that what
I claim is:
1. The hereinabove described improved steel free from or low in manganese
and capable of being hardened in the mass as set forth, and consisting of iron,
carbon, chromium and nickel with aluminium or silicon, or aluminium and silicon,
substantially as herein described.
2. The hereinabove described improved manufacture of chromium-nickel steel
free from or low in manganese and capable of being hardened in the mass as set
forth, using as a basis iron decarbonized. demanganized and desiliconized by the
pneumatic method or by the open hearth method. with carbonizing physic,
chromium and nickel with aluminium or silicon or aluminium and silicon, as
set forth.
3. The manufacture of the herein described chromium-nickel steel by decar-
bonizing, demanganizing and desiliconizing iron and adding carbonizing physic.
chromium, and nickel with aluminium or silicon or aluminium and silicon to
the decarbonized, demanganized and desiliconized iron the iron and other sub-
stances being mixed together in a molten state in a ladle or vessel that is adapted
by suitable weighing mechanism to show the weight of its contents and the said
iron and other substances being added separately and successively so that the
weight of each and consequently the proportion thereof can be easily controlled,
substantially as set forth.
4. The hereinabove described steel consisting of iron, carbon, chromium and
nickel, and aluminium or silicon, or aluminium and silicon, substantially in or
about the proportions set forth.
Dated HIS 40 HIV OF PUSU 1990.
For the Applicant,
W. LLOYD WISE,
46. Lincoln's Inn Fields, London, W.C., Chartered Patent Agent.