Improvements in the Method of Making Metal Plates, Ingots, or Blocks, and Furnaces used therein.
Year: 1893

page_text: Date of Application, 11th Jan., 1893-Accepted, 6th Jan., 1894
COMPLETE SPECIFICATION.
Improvements in the Method of Making Metal Plates, Ingots, or
Blocks, and Furnaces used therein.
I, JOHN BAPTISTE NAU, Metallurgical Engineer, a citizen of the United
States, residing at No. 45, Washington Street, in the City and County of
Allegheny and State of Pennsylvania, U.S.A., 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 for its special purpose the manufacture of certain classes of
metal plates, blocks or ingots, of whatever shape desired, that require different
composition and different physical characteristics in different parts, as is the case
with steel armour plate, for instance.
In carrying out my invention, I introduce into the metal, while molten, in a
suitable mould, such element. or elements, as for instance, manganese, silicon,
carbon, titanium, chromium, tungsten, etc., or any other element or elements that
it may be desired to introduce in some special side or part of the metal, and not in
other parts. If, however, the entire mass of metal be liquid when these additions
are made, some of the elements added would descend into lower regions or planes
of the mass, where they are not intended to be incorporated. To avoid this, I
propose that such lower regions shall be brought to a semi-solid, pasty, or solid
condition, while the surface and upper portion of the mass is more liquid; that is
to say, the bottom or distant surface may be solid and the adjacent metal semi-
solid or pasty in different degrees, and as the upper surface is approached, the metal
is liquid or the bottom may be more or less pasty and the mass gradually more
liquid as the top is approached or the top may be semi-liquid and the mass
become more solid as the bottom is approached. To obtain these results, means
for cooling some part of the metallic mass may be provided. By these means it
will be possible to keep one part of the mould containing the metal at a lower
temperature than other parts, by having it exposed to the air, or a forced current
of air, or to water, steam, or any other cooling medium, in order to cool the metal
or solidify it in that particular part or zone; whereas other regions or zones may
be kept liquid longer in order to obtain the desired effect above suggested. Thus,
for instance, by cooling the bottom, and, if desired, other lower parts of the moulds
by air or any other cooling medium, this region of the metal will be solidified,
whereas the zone immediately above and in contact with the solidified portion will
be pasty, and the upper or top zone will be liquid. In this state it will be possible
to increase the percentage of carbon or manganese or titanium or tungsten or
silicon or chromium or any other element or elements that it is desired to have
in larger proportions in the liquid regions, by making the ordinary addition of, for
instance, spiegel, ferro-manganese, ferro-silicon, ferro-phosphorus, ferro-titanium, or
ferro-chromium, or any other substance or substances that, when introduced either
in liquid or solid or gaseous form, will incorporate the desired element into the
liquid portion of the mass. Of course, by so doing, the upper portion of the metal
which has been kept in the most liquid state will absorb most of the elements
introduced, whereas that portion of the metal that is partly liquid or more or less
pasty, lying between the liquid and solidified metal, will receive less of that
element, or elements, and the solidified region will receive none of it. By this mode
of operation a gradual decrease of the percentage of the substance or substances
that are introduced will be obtained from the most liquid to the solid regions.
This gradual or uniform decrease of this element or elements will give a final piece,

page_text: plate or ingot, the character of which will not be impaired by a sudden change in
its composition in any zone or plane. The addition of these elements to a partly
liquid, partly pasty, and partly solidified metal may be made to any previous
compositions, such as ordinary Bessemer steel, or open hearth steel, or crucible
steel, or liquid soft iron, or to metal obtained by any method and of any previous
composition or nature.
It must be distinctly understood that I do not claim as my invention the mere
addition of any recarburizing element or any other substance to a mass of metal
liquid or solid in order to incorporate some outside elements into the metal and to
give the product to be obtained certain homogeneous qualities, as I am well aware
that such additions have been, and are daily made.
My invention, on the contrary, comprehends a process, whose principal object is
to obtain a product that is heterogeneous in its composition and physical
characteristics, by the incorporation of other substances into certain defined zones
of a metallic mass, which substances, by their varying percentages in the different
zones or parts of the metallic mass, will impart to the metal different physical
characteristics due to the different compositions in the different zones, these results
being obtained by causing, through any suitable means, the metallic mass to
solidify or become pasty in some regions, whereas still other regions are kept liquid
while desired substances are incorporated into or added to the mass.
The liquid or pasty surface of the metal may, if desirable or necessary, be
covered by suitable materials, to prevent undesirable action due to the contact
therewith of the heating flame or products of combustion.
I wish it to be distinctly understood that I do not limit myself as to the time at
which I intend to make this addition to the metal. They can be made at any
moment after the metal has been cast, with its already ordinary addition, if such
there be, and before that part of the metallic mass that is intended to receive the
further addition, has been left to solidify or become pasty only. It can be made
to metal, which, after having been cast and even cooled down, is made by the
application of any means to be liquefied again or simply made pasty to any depth
in that region where the addition is intended to be made or even is made to be
liquid again, entirely by the use of any known means, and then made pasty or
solidified again in one part, whereas that portion of metal where the addition is to
be made will be kept liquid or pasty through whatever means may be deemed best
suitable to obtain and maintain this pasty or liquid state.
I also wish to state that the mould employed may be of any shape and form, and
that the addition or additions to the metal therein may be made after having
removed the upper part of the ingot, should it be found that this part presents a
hollow space or is generally unsound, as is often the case. After the removal of
such a part, the remainder would receive the addition as has been described above.
To keep the upper part of the metal liquid, or even the whole mass, or even to
liquefy already solidified metal, I do not limit myself as to the means to be used,
these means being only an accessory to the process and only employed to obtain
the desired results.
The whole mass of metal can be kept liquid for a certain length of time, or only
a portion thereof, whereas the remainder can be left to solidify, or a once solidified
and already cooled down mass may be liquefied again entirely or partly by the
application of any heat creating means, such as solid, liquid or gaseous fuel, or
electricity, either separately or collectively, or also one or more of these means
combined together.
I also wish to state that, should it be considered desirable that the ingot or plate
or metal block should contain certain elements and have certain characteristics, on
one side or.end and other elements and other or different characteristics at the
other end or side, for instance, should it be desired to have tungsten or any other
element or elements or compounds at one end or side, and manganese or titanium
or any other element or elements or compound at the other end or side, then the
tungsten or any other element would be incorporated into the particular side or end,

page_text: while that side or end is still liquid or pasty, or when already solid, has been again
made pasty or liquid through the application of any heat-giving appliance. After
the incorporation of the desired element on this particular side, the manganese or
titanium or any other element will be introduced into the other end or side of the
plate which has been rendered pasty or liquid for that purpose after the first end
or side has been solidified in its turn.
The furnace that I prefer to use to keep the upper part of the ingot liquid,
while the lower part is being solidified, is a furnace similar to the one illustrated in
the drawings accompanying this Specification.
In the drawings,
Figure 1 represents a longitudinal vertical section on the line A;
Figure 2, a vertical cross-section on line C D ; and
Figure 3, a plan.
In the three figures, similar letters represent similar parts.
E is a hydraulic cylinder located in the center of the foundation and supported
by a cast iron plate F, bolted to the foundation; G is a hydraulic piston
supporting a horizontal plateau H, to which are fastened two rails 1. On these
rails is run a car K, mounted on four wheels. On the platform of the car rests
the bottom L of the mould. This bottom is made of cast iron and inside of it is
located a coil of iron pipes to receive water for cooling purposes. The top of the
bottom of the mould may be lined with refractory material, if judged necessary.
On this bottom rests the mould M. This mould may be made of cast iron or
wrought iron sheets bolted or rivetted together. In the drawing the envelope is
supposed to be made of wrought iron sheets. It presents at the lower end a
double wall with a clear space between. This clear space is larger at the bottom
and decreases to nothing at its upper end. On the drawing it is supposed to run
to about the middle of the height of the mould. This space may be run however
clear to the top of the mould between a double envelope. The purpose of the
space is to cool the lower part of the ingot by a circulation of water or other
medium in the space around the mould. The water may be introduced into the
space by means of a pipe located at any point and run off in a similar manner.
The coil in the bottom plate also receives its water through an inlet a and after
having circulated through the coil, the water is run off through another aperture.
As this entire construction has to be raised at will, the aperture a, as well as the
other apertures are connected with any water conduit by means of rubber pipes or
flexible or telescoping metallic pipes. The mould has an inside refractory lining r,
thick at the top, and reduced to almost nothing at the bottom. The thick part of
the top will keep the heat a long time, and consequently keep the metal in the
mould liquid or semi-liquid at the top, while the lower thinner part of the refractory
lining allows the ingot to be cooled and solidified in this region. The whole is
placed in a reverberatory furnace N, of the ordinary type, or any other type. The
Siemens type is shown here. R and R' are the heat regenerators. R, for gas, and
R', for air. The flues fand f¹ carry the heated gas and air to the furnace, on one
side and lead it off on the other side. d d are two doors on one side of the furnace
and may be placed on both sides. is a hole placed in the roof of the furnace, through
which the liquid metal is cast into the mould M. Other holes may be placed in
the roof above the mould, in order to measure, by plunging iron bars in the bath,
how high the metal has been solidified. T is a railroad track on which the truck
When an
runs, permitting the mould to be run into the furnace or taken away.
operation is to be made, the piston G is down in the cylinder E, the car carrying
the mould is pushed over the track T, on top of the plateau H, and then kept in
place by whatever means may be used. Then the mould is raised to the position
shown on the drawing. This mould is empty as yet. Heat is now applied to the
furnace and the mould is heated inside by the reverberation of the flame to the
right temperature, whereas both the bottom and the lower part of the mould are
kept cooler by the circulating water. This cooling can also be begun immediately
as just described, or sometimes after the metal has been cast in the mould. When

page_text: the mould is sufficiently heated the liquid steel is poured through the hole h,
while heat is still being applied. This heat is kept up in order to prevent the
surface of the metal from solidifying. When the lower part has been solidified to
a sufficient height, while the upper part is kept liquid or semi-liquid, the desired
addition may be made either through one of the doors d, by means of a run or
through the hole h. When the necessary reactions have taken place the heat is
shut off in order to allow the metal to solidify to the top. To accelerate or
maintain the complete and final solidification, the mould can be partly or entirely
lowered, which action will bring it into a colder region. After complete solidifi-
cation the car with mould and ingot is pulled out over the track T. The ingot is
stripped of its mould and is now ready to be transformed into the desired shape
either by rolling, or hammering or hydraulic pressure or any other means.
The
so obtained product will now be ready to be hardened, either in water or oil, or
by any other means whatever, if it is found necessary to harden it. A steel plate
treated by the above described method, will constitute an article, which not only
will have a different composition in the different zones, but on account of the gradual
change in its composition, its physical characteristics, such as hardness, or toughness
or malleability, etc., will also gradually change from one side to the opposite side,
and whereas one side may be very hard and resistant, the opposite side can be left
very soft and yet remain very tough. During the casting of the metal into the
mould and during its exposure to the heat in the furnace, the flame is preferred to
be a reducing one in order to prevent any oxidation of the metal. The metal
being exposed during the whole operation to the reducing flame, can only be
improved in quality. Though this is a description of a special furnace, I wish to
state that any other furnace may be used as well as any other means adapted to
carry out my invention, may be employed.
The pouring of liquid metal into an entirely heated up mould, exposed further-
more at its upper end to a very high temperature, whereas the lower end is made
or allowed to cool down slowly and gradually from the lower regions towards the
upper regions, has for effect that the metal will be kept liquid longest in the upper
regions and the last portion of the metal to be solidified will be the upper surface
region.
By so doing, not only will it be made possible to introduce other elements into
this particular region of the metallic mass, but the formation of blow holes and
especially the hollow space which is so often found at a small distance from the
upper surface of otherwise sound ingots or blocks, will be completely avoided. A
perfectly sound and dense block without honeycombed structure will be produced.
Thus, by this method, a double end is obtained, viz.: (1) a sound metallic block,
without blow holes or hollow spaces at the upper end, and (2) the possibility, by
making further additions as hereinbefore described, of obtaining the desired
heterogeneous product.
Having now particularly described and ascertained the nature of my said inven-
tion, and in what manner the same is to be performed, I declare that what
I claim is-
1. The herein described process of producing heterogeneous metal blocks with
different physical characteristics and different compositions in different zones,
which method consists in causing the upper side or surface of a mass of homo-
geneous iron or steel contained in a suitable vessel (and having its upper surface
subjected to a high heat) to be liquid or semi-liquid and the bottom solid, then
introducing into the liquid side additional material of different nature and
composition which will unite with the original metal, thereby producing a block of
heterogeneous metal whose composition and qualities will gradually vary from the
liquid side through the pasty region to the opposite side, and then allowing the
mass to solidify, as and for the purpose set forth.
2. The herein described process of producing heterogeneous nietal blocks with
different physical characteristics and different compositions in different zones,

page_text: which method consists in causing the upper side or surface of a mass of homo-
geneous iron or steel contained in a suitable vessel (and having its upper surface
subjected to a high heat) to be liquid or semi-liquid, and the other side solid,
then introducing into the liquid side additional material of different nature and
composition which will unite with the original metal, thereby producing a block
of heterogeneous metal whose composition and qualities will gradually vary from
the liquid side through the pasty region to the opposite side, and then allowing
the mass to solidify, then reducing the solidified mass into a plate of the desired
thickness and dimensions, thereby obtaining a steel plate of heterogeneous
character, gradually varying in composition from one side to the other, and then
hardening the same by any known process.
3. The herein described process of producing sound heterogeneous metal blocks
without honey-combed structure and with different physical characteristics and
different chemical composition in different zones, which method consists in causing
the upper side or portion of a mass of liquid iron or steel contained in a suitable
vessel to be exposed to a high temperature while the lower regions are exposed to
a lower temperature, whereby a slow and gradual solidifying of the mass from the
lower toward the upper region may be obtained, then, when this upper region is
still liquid or semi-liquid, or pasty introducing into it additional material of
different nature and compositions, which will unite with the original metal and
produce a block of heterogeneous metal whose composition and qualities will
vary from the liquid side through the pasty region to the opposite side, then
allowing the mass to solidify gradually and last in the upper surface, substantially
as and for the purpose set forth.
4. The method substantially as herein described of producing metal blocks,
ingots or plates, having different physical characteristics and different chemical
compositions, in different planes or zones.
5. The hereindescribed method of producing metal plates blocks or ingots free
from blow holes or hollow spaces, which consists in pouring in the metal into a
heated mould, exposing the upper end or face thereof to a high temperature
and allowing the mass of metal to cool to a solid form gradually from the lower
region toward the upper region or face.
6. A metal furnace substantially as herein described, having a movable bottom
constituting a mould, and means for raising and lowering said bottom, whereby it
may be raised into position for the treatment of the metal and lowered for
removal from the furnace.
7. The metal furnace constructed and operating substantially as herein
described.
Dated this 21st day of December 1892.
JOHN BAPTISTE NAU.