Improvements in the Process of Casting Armour Plates and other Objects and to Moulds for use therein.
Year: 1892

page_text: Date of Application, 8th Nov., 1892-Accepted, 10th Dec., 1892
COMPLETE SPECIFICATION.
Improvements in the Process of Casting Armour Plates and other
Objects and to Moulds for use therein.
We, GEORGE HOWLAND CHASE Metallurgist of No. 106 Harvey Street,
Germantown City of Philadelphia, State of Pennsylvania, and HENRY LAWRENCE
GANTT, Mechanical Engineer of No. 7 East Penn Street, Germantown, City of
Philadelphia State of Pennsylvania, both in the United States of America, 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 :-
Our invention has relation to the manufacture of steel, armor, rolls and other
objects requiring a hardened surface, and consists in improved process for casting
armor, plate, etc. as hereinafter particularly described.
The object of our invention is to produce in a single piece of steel a surface or
surfaces which shall be of a different degree of hardness from the interior portion
or other surfaces of the same piece. In other words the object is to produce in a
single piece of steel a hardened exterior grading into a softer interior or rear
surface.
A special application of our process is in the manufacture of steel castings for
armed vessels or forts.
The objection to the chilled iron which is now principally used in fort construc-
tion is that although the surface is extremely hard the metal is exceedingly brittle,
and readily cracks under the impact of shots fired from the high power guns. The
ordinary steel castings do not break or crack but are not hard enough to resist the
projectiles. By our method we provide a surface, nearly, if not quite as hard as
chilled iron with a back or interior of softer material.
Our method also provides among numerous other important structures a valuable
roll for rolling mills having both a hard surface and of great strength, both of
which features are essential in this class of rolls. The same also applies to dies
for hammering iron and steel.
When molten steel, or other alloy of iron, is brought into contact with a wall
composed or partially composed of manganese, silicon, or other fusible material
with which the steel will alloy, the surface of the metal in immediate contact with
the aforesaid fusible material will alloy therewith and produce a harder steel, as
will also the parts of the metal adjacent to such surface, such portions graduating
in hardness towards the interior until beyond reach of the effect of the alloying
surface when the interior or rear portions are of the same composition and hardness
as provided in the original composition of the metal when poured into mould; and
softer than that operated upon by the alloying surface or surfaces.
We are aware that broadly speaking the process of hardening by the employ-
ment of carbon is not new, but that carburizing wholly or partially the surface of
ingots or plates of metal to a given depth has been known. We, however, have
discovered that fusible metallic alloys when brought into contact, as in mould
walls, with the molten steel by reason of their chemical composition in alloying
with the metal and of their fusible character, produce superior results. We
have carefully experimented with various fusible alloys in mould walls or linings
and have discovered that those which produce the best results are mould walls
of fusible alloys composed largely or in part of such hardening materials as
speigeleisen, ferro-silicon, silico-speigel, ferro-manganese, ferro-chrome and ferro-
tungsten, &c. The chemical properties of these are such as to alloy in a highly
satisfactory manner with the molten steel coming in contact therewith and to
uniformly harden the face of the steel graduating in hardness towards the interior.

page_text: The accompanying drawing illustrates a mould of ordinary construction having
an interior wall composed of fusible metallic alloying material.
Fig. 1 is a sectional view on the line x-x of Fig. 2.
Fig. 2 is a plan view.
A is the upper section of the casting of the mould box of ordinary construction
and A' is the lower section joined together, as indicated in the drawing by bolts,
or other suitable means, so that the sections can be separated after the casting
has been made, and in this manner removed from the mould. B is the inner
chamber of the mould into which the molten steel is poured through the runner, b.
In the drawing only one wall, 6', of the chamber, B, is composed of the
alloying material, while the remaining walls are composed of sand or other suitable
material.
In carrying out our invention moulds of a desired size and shape are provided,
the walls of which are composed wholly or partially of any material which will
fuse and alloy or combine with the heated steel and harden the same, as described.
Other fusible materials may be employed which produce a like effect, though as
before described speigel-eisen, ferro-silicon, silico-speigel, ferro-manganese, ferro-
chrome and ferro-tungsten, and similar metallic alloys are preferable.
The molten steel of any desired composition is run or poured into the said
moulds when the molten metal coming in contact with the prepared walls fuses the
inner surfaces of such walls and combines or alloys therewith hardening the surfaces
of said steel and such parts as are adjacent thereto, the hardness diminishing
toward the interior. All the walls of the moulds may be composed of the alloying
material, or where it is desired to harden only the one surface of the steel but one
wall of the mould is composed of such material, while the other walls are constructed
of any suitable non-alloying material.
The inner stratum only of one or more of the walls of the mould may be only
partially composed of the alloying material, or the walls may be largely composed
of the same, if desired, the alloying material may be applied to the walls of the
mould as a lining in any desired' manner.
It is to be noted that our steel after being cast may be treated by any of the
well known methods in vogue for improving the quality of cast steel, such as
forging, rolling, oil tempering, annealing, hardening and toughening.
When a required piece of armor is of such a simple shape as may be forged or
rolled from a mass of cast steel of another shape, the armor will probably be all
the better for such working.
Having now particularly described and ascertained the nature of our said inven-
tion and in what manner the same is to be performed we declare that what we
claim is :-
1. The process of producing a steel casting having a hard surface gradually
decreasing in hardness from the surface consisting in providing a dry mould with a
lining or facing of a readily fusible alloy, pouring steel into said mould and causing
said alloy to be fused and entirely incorporated by alloying with the outer portion
of the molten steel, and cooling and removing the casting from the mould, as set
forth.
2. The process of producing steel castings having a hardened surface or surfaces
gradually decreasing in hardness toward the interior consisting in pouring molten
steel into a mould of dry sand, one or more of the inner walls of which is provided
with a lining or facing composed wholly or in part of a readily fusible alloy and
causing said alloy to be fused and entirely incorporated by alloying with the
outer portion of the molten steel and cooling and removing the casting from the
mould as set forth.
a
3. The process of producing a steel casting having a hard surface gradually
decreasing in hardness from the surface consisting in providing a dry mould with
lining or facing composed in part of an alloy containing ferro-chrome, pouring
steel into said mould and causing the said alloy to be fused and entirely incorporated

page_text: by alloying with an outer portion of the molten steel, and cooling and removing the
casting from the mould, as set forth.
4. The process of producing steel castings having a hardened surface gradually
decreasing in hardness toward the interior consisting in providing a dry mould with
a lining or facing composed wholly or in part of manganese alloy, pouring the steel
into said mould and causing said alloy to be fused and entirely incorporated by
alloying with the outer portion of the molten steel and removing the casting from
the mould when sufficiently cooled substantially as described.
5. The process of producing steel castings having a hardened surface or surfaces
gradually decreasing in hardness from the surface consisting in pouring molten
steel into a dry sand mould, said mould having one or more of the inner walls
provided with a lining or facing composed wholly or in part of ferro-manganese and
causing said alloy to be fused and entirely incorporated by alloying with the outer
portion of the molten steel and removing the casting from the mould when sufficiently
cooled substantially as described.
6. A casting mould, one or more of the inner walls of which are composed of a
fusible alloy adapted to fuse with molten steel coming in contact therewith and to
alloy with the same hardening the outer surface or surfaces substantially as
described.
HASELTINE, LAKE & Co.,
45, Southampton Buildings, London, Agents for the Applicant.