IMPROVEMENTS IN THE MANUFACTURE AND TREATMENT OF TOOL STEEL
Year: 1885

page_text: I ROBERT HADFIELD of Attercliffe Sheffield, Steel Manufacturer do hereby
declare the nature of my invention for IMPROVEMENTS IN THE MANUFACTURE
AND TREATMENT OF TOOL STEEL to be as follows:-
My present invention relates more particularly to the production and manu-
facture of those kinds of tool steel which are known as merchant steel sate chisel
and boring steel and has for its object to greatly reduce the cost of production
thereof.
This I effect by substituting for the expensive brands of iron at present used in
the manufacture of such steels any suitable ordinary iron such as the "crop ends"
of iron or steel rails or pig iron either wholly or to a great extent decarbonised
refined or otherwise treated by any of the steel making processes and adding
thereto carbon in the form of common hematite or white iron or other cheap
carbonaceous iron in combination with Silicon the carbonaceous iron being advan-
tageously added in proportions varying from about four per cent (4%) up to
about fifty per cent (50%) and the Silicon being beneficially combined there with
in per centages varying from about three quarters per cent (%) up to about one
and a half per cent (1º).
.
Both the Silicon and carbon are added to and melted along with the materials
under treatment; or whilst such materials are in a state of fusion and the exact
per centages of Silicon and carbon to be used are governed by the character of the
materials treated and also by the product desired to be obtained according as a
harder or softer steel is required.
The lower per centages of both are suitable when making the milder kinds of
tool steel while such per centages are increased according to the degree of hardness
required in the resultant product.
I am aware that the use of ordinary iron combined with common hematite or
white iron or other cheap carbonaceous iron has hitherto been considered im-
practicable in the manufacture of tool steel owing to the high per centages of
sulphur contained in such irons being deemed injurious and consequently up to the
present time expensive high class Swedish and other irons have been used for such
purpose.

page_text: I have however discovered that by my novel and beneficial use of carbon and
Silicon in the manner hereinbefore mentioned the bad effects of the sulphur and
phosphorus are neutralised and by mixing and combining irons of the kinds before
mentioned I obtain a very superior product corresponding in character and equal
or superior in quality to the present expensive chisel boring sate and other similar
steels at a comparatively low cost.
I add manganese in the usual way to the steel produced by my improved process
so that it can be forged, hammered rolled or otherwise treated as desired-When
however the materials used in its production contain an excess of manganese any
further addition thereof becomes unnecessary, and such addition is only requisite
when there is a deficiency of manganese in the materials used.

page_text: I, ROBERT HADFIELD of 33 Southampton Buildings Holborn London, 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:
My present invention relates more particularly to the production and manu-
facture of those kinds of tool steel which are known as merchant steel Bate chisel
and boring steel and other tool steels and has for its object to greatly reduce the
cost of production thereof.
The principal constituents of my improved steel are iron (Fe) silicon (Si) and
carbon (C) and such improved steel has in fact a much larger proportion of silicon
than has heretofore been employed in the manufacture of steel adapted for the
purposes of tool steel; for which purposes my improved steel is specially adapted.
The injurious effect of the presence of sulphur and phosphorus in the cheaper
qualities of iron has largely prevented their use in the manufacture of high grades
of steel, and has consequently made the cost of production of such steel much
greater than if ordinary low grades of iron could be employed I have discovered
however that by adding silicon and carbon to iron in certain proportions the same
capacity for hardening and tempering is acquired by the iron with which they are
incorporated, as is given to iron by the addition of carbon only in the ordinary
steel making processes heretofore practised with this peculiar advantage however
in favor of using both silicon and carbon instead of employing carbon only that
the steel made with silicon and carbon instead of with carbon only is softer and
more easily worked before tempering and becomes harder though less brittle after
tempering than carbon steel I have also discovered that when the silicon is present
in sufficient quantity say from three fourths to one and a half per cent, I can use
as my carbon addition, white hematite iron of such a comparatively low grade as
is now unfit for steel making, owing to its high sulphur as the silicon has the effect
of neutralising the injurious effects of the sulphur and phosphorus and I thus
obtain a steel giving the same results as the high class steels, made from expensive
foreign and other irons, which irons are comparatively free from sulphur and
phosphorus-This remark also applies to the presence of sulphur and phosphorus
in any part of the charge from which my steel is made the resulting product being
of very superior quality although made with comparatively cheap materials.
My present invention therefore consists in making an alloy or mixture of iron,
silicon and carbon in the proportions hereinafter set forth, as I have discovered
that when the proportion of silicon is below one and a half per cent in the
resulting steel the addition of carbon in the proportion of from about one fourth of
one per cent to about two and one half per cent secures in the resultant product
the advantages arising from the use of silicon before mentioned together with the
capacity of hardening and tempering possessed by ordinary steel.
I am aware of course that both silicon and carbon have been present in steel
made before my invention; but it has always been considered that silicon and
6. "

page_text: carbon must not either of them be high when both are present in steel, and
0.15 per cent of silicon has been considered very high for steel which is worked,
and one half per cent very high for steel to be used for castings, so that it has
always been regarded as a rule that where silicon was high in the comparative
sense just referred to, carbon must be low, and vice versa and that tool steel, and
steel required to receive a sharp cutting edge should be as nearly as possible
absolutely free from silicon.
The condition of the iron which forms the basis of my improved steel and from
which it is manufactured, may be that of ordinary pig metal, cast iron, wrought
iron, steel or iron scrap or a mixture of any or all of those, and the process or
processes by which the iron or steel is manufactured or reduced or subsequently
treated is immaterial, the only necessary requirement being that the iron before
the introduction of the carbon and silicon additions should be substantially
decarburised, by which I mean not necessarily devoid of carbon, but that the
metal should be or should have been previously decarburised wholly or to a great
extent. Hence my improved process is applicable to the manufacture of iron and
steel by means of the Bessemer open-hearth or crucible processes, these processes
being carried on in the usual way as to the first two named until the metal under
treatment is nearly or quite decarburised and then the desired per centages of
silicon and carbon are added; while if the crucible process is employed, the silicon
and carbon additions may be introduced at any stage of the process.
In the introduction of the silicon addition however it must be observed that it
is essential that if the Bessemer or open-hearth processes are employed, the silicon
and carbon additions must be introduced after the iron has been decarburised as
completely as it is intended that it should be decarburised, for the reason that in
the oxidising process necessary for decarburising the charge the silicon present in
the charge will be to a great extent oxidised and almost entirely eliminated before
the carbon is attacked so that if the silicon addition were introduced previously to
or during the decarburising operation it would not remain in the charge or be
found present in the resultant product.
In practising my invention the charge may be composed of pig metal, cast iron,
scrap or a mixture of these with steel or wrought iron scrap which are melted
desiliconised and decarburised in the ordinary way after which as before stated the
charge will then be almost entirely free from silicon When the charge is refined
in the open hearth process and the blow is finished in the Bessemer process the
carbon and silicon additions are introduced into the charge-The carbon addition
consists of hematite pig metal of cast iron or other carbonaceous iron The amount
of carbon charge will be from about four to about fifty per cent of the total
charge, according to the per centage of carbon contained in the pig metal used for
the carbon addition and the per centage of carbon desired in the resulting product.
The silicon addition consists of silicon pig iron (a well known product of the
blast furnace process) or other ferro silicon-The gross amount of silicon addition
to be used will also depend on the per centage of silicon which the silicon pig
contains; and the per centage of silicon which the resulting steel is to contain
The carbon addition and the silicon addition may be introduced either separately
or combined and in pigs or in a broken up condition, and preferably heated, or
better still in a melted state-I prefer to use as the silicon addition, silicon pig
which contains from eight to ten per cent of silicon for the reason that such
material being a special product is more uniform in its quality and constituents,
and also because it is low in carbon which is important, as an unknown amount of
carbon in the silicon addition adds an element of uncertainty as to the amount of
carbon remaining in the final product I therefore prefer to add the carbon by
means of a separate addition viz in the shape of what is herein before described as
a carbon addition vary the resulting product between three fourths and up to
one and a half per cent of silicon according to the purpose for which the material
is to be used; also the amount of carbon in the same way-For example if a mild
form of steel is required such as chisel steel I keep the silicon and carbon at the

page_text: lower per centages varying and increasing the proportions as greater hardness is
required After the silicon and carbon additions are incorporated with the charge,
it is ready to be run into ingots or other forms as may be desired.
Manganese may be added to my improved steel in the usual way and
proportions.
When however the materials used in its production contain sufficient Manganese
any further addition thereof is unnecessary and such addition is only requisite
when there is a deficiency of manganese in the materials used.
If the crucible process is used for the production of my improved steel the basis
of the operation or prime charge being wrought iron or steel scrap or both com-
bined the process is then conducted in the usual way and the carbon addition
together with the silicon addition may be introduced in the crucible with the
prime charge or at any subsequent stage of the process.
The range of proportions of silicon and carbon contained in the resulting steel
which I desire to secure as my invention in this patent, is any amount less than
one and a half per cent and not less than three fourths of one per cent of silicon
and from one fourth of one per cent up to two and one half per cent of carbon.
Having now particularly described and ascertained the nature of my said
invention and in what manner the same is to be performed I declare that what
I claim is
The production and manufacture of tool steel of the kinds known as merchant
steel and sate chisel and boring steel and other tool steels such steel containing in
combination both carbon and silicon, said ingredients being in the proportions of
from one fourth of one per cent to two and one half per cent of carbon, and from
three fourths of one per cent up to any amount below one and one half per cent
of silicon as herein before specified.