Improvements in the Manufacture of Steel."
Year: 1896

page_text: Date of Application, 16th Dec., 1896
Complete Specification Left 26th Aug 1807 Accented 11th Doc.
4007
PROVISIONAL SPECIFICATION.
"Improvements in the Manufacture of Steel."
I, CANDIDO DE ESTEVE LLATAS, of 38 bis, Avenue de la Republique, Paris, in the
Republic of France, Engineer, do hereby declare the nature of this invention to be
as follows:-
This invention relates to the manufacture of steel, and has for its object the
production of steel of the highest qualities (such, for example, as that commonly
known as crucible steel), each quality possessing remarkable uniformity, and the cost
of production being but little in excess of that of Bessemer,' 'Siemens-Martin' or
other steel of like class.
As the result of numerous experiments, I have found that, in the production of
steel possessing the various qualities or characteristics suited to the different purposes
to which this metal is applied, it is necessary that Carbon, Manganese and Silicon
should be present in certain definite proportions; and further that a regular
gradation prevails between these elements; the proportions of carbon and silicon
being on the ascending scale, as between mild and hard steel, whilst the proportion
of manganese is on the descending scale. It is well known that an augmentation in
the proportion of carbon has the effect of increasing the hardness of steel; but in
manufacturing steel of different qualities according to my improved method, not
only is the proportion of the carbon varied, but those of the manganese and silicon
are also regulated according to a definite scale.

page_text: From this table it will be seen that, with each increase of 0.050 of carbon, there
is a decrease of 0.025 of manganese and an increase of 0.025 of silicon, and that
no single element is ever varied without both other elements being also varied in a
definite ratio.
In carrying my improved process into effect, I melt the charge in a Bessemer or
other converter or in a Siemens-Martin or other suitable furnace, and proceed until
the bath is brought to the desired point of purity as regards the proportion of carbon
present, according to the particular quality of mild, medium or hard steel required.
If the proportion of carbon be lower or higher than that specified in the column
selected, I carburize or decarburize the bath until the proper proportion is reached. In
carburizing, carburetted iron of any suitable kind may be introduced into the
bath.
When the bath presents-or by carburation or decarburation has assumed-

page_text: the desired condition as regards the proportion of carbon present, the necessary
quantities of manganese and of silicon are added, so as to produce a metal which,
on tapping, presents the proportions indicated in the particular column of the table
for the time being in use. The manganese and the silicon before being introduced
are heated to a cherry red.' When operating with the aid of a Bessemer or other
converter, these materials may be introduced simultaneously; but when a Simens-
Martin or similar furnace is employed, the manganese is first introduced, and when
this has been absorbed, the silicon is added. The latter having been absorbed, the
tapping takes place.
COMPLETE SPECIFICATION.
"Improvements in the Manufacture of Steel."
I, CANDIDO DE ESTEVE LLATAS, of 38 bis, Avenue de la Republique, Paris, in the
French Republic, Engineer, 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 relates to the manufacture of steel, and has for its object the
production of steel of the highest qualities (equal for example to that commonly
known as crucible' steel), the product possessing remarkable uniformity, and
the cost of manufacture being but little in excess of that of "Bessemer," or
Siemens-Martin' or other steel of like class.
As the result of numerous experiments, I have found that, in the production of
steel possessing the various qualities or characteristics suited to the different
purposes to which this metal is applied, it is necessary that carbon, manganese and
silicon should be present in certain definite proportions; and, further, that a regular
gradation prevails between these elements; the proportions of carbon and silicon
being on the ascending scale, as between mild and hard steel, whilst the proportion
of manganese is on the descending scale.
It is well known that an augmentation in the proportion of carbon has the effect
of increasing the hardness of steel; but in manufacturing steel of different grades
according to my improved method, not only is the proportion of the carbon varied,

page_text: but the proportions of the manganese and silicorn are also regulated according to a
definite scale. The scale is substantially as follows:-
Quality or Grade.
Carbon per cent.
Manganese per cent.
Silicon mer cent

page_text: When the charge presents--or by carburation or decarburation has assumed-the
desired condition as regards the proportion of carbon present, the necessary quantities
of manganese and of silicon are added, so as to produce a metal which, on tapping,
presents the proportions indicated in the particular line or column of the table for the
time being in use. The inanganese and the silicon before being introduced are
heated to a cherry red.' When operating with the aid of a Bessemer or other
converter, these materials may be introduced simultaneously; but when a
Siemens-Martin or similar furnace is employed, the manganese is first introduced,
and when this has been absorbed, the silicon is added. The latter having been
absorbed, the tapping takes place.
Having now particularly described and ascertained the nature of this invention
and in what manner the same is to be performed, I claim :-
In the manufacture of cast steel of various grades from that containing 0.150 per cent.
of carbon, 0.625 per cent. of manganese and 0.025 per cent. of silicon for mild
steel to that containing 1.000 per cent. of carbon, 0.200 per cent. of manganese
and 0.450 per cent. of silicon for hard steel, the herein described method of
manipulating the charge which consists in varying the proportions of carbon,
manganese and silicon in the definite ratios set forth according to the grade of steel
required; the proportion of the manganese being diminished 0.025 per cent. and
that of the silicon being increased 0.025 per cent. for each increase of 0.050 per cent.
in the proportion of the carbon.
Dated this 25th day or August, 1897.
For the Applicant,
G. G. M. HARDINGHAM,
Chartered Patent. Agent, 191, Fleet Street, London, E.C.