Process for Rendering Iron, Steel, and similar Metals Homogeneous.
Year: 1892

page_text: Date of Application, 24th May, 1892-Accepted, 25th June, 1892
COMPLETE SPECIFICATION.
Process for Rendering Iron, Steel, and similar Metals
Homogeneous.
I, JOSEPH CRESSON FRALEY, of No. 714 Walnut Street, Philadelphia, United
States of America, Lawyer, do hereby declare the nature of this invention and in
what manner the same is to be performed to be particularly described and ascer-
tained in and by the following statement reference being had to the accompanying
drawing, which illustrates a form of apparatus adapted for the conduct thereof:-
My invention, though primarily intended for use in connection with iron and
compounds or alloys thereof, such as steel of all kinds and grades, embraces in
principle other metals which are analogous to iron, in the particular of substantial
susceptibility to magnetic influence.
The most complete and characteristic application of the process is as an adjunct to
the manufacture of castings, by which term I include both ultimate products, and
initial products (such as ingots) intended for further treatment, but the beneficial
effects of my invention are not restricted to casting processes and, as will be
specified hereafter, it is capable of a more general application.
Broadly speaking, the process consists in exposing the metal in a heated state,
within a magnetic field, and repeatedly varying or modifying the character of
such magnetic field whilst permitting the metal to cool.
The main objects of this treatment are as follows:-If applied to metals in a
fluid condition, it facilitates, during the period of fluidity, the disengagement or
definite localization of foreign substances, such as occluded gases, and, both during
the period of fluidity and thereafter (whilst the particles are more or less mobile)
modifies the internal structure of the mass in the direction of hindering the forma-
tion of large crystals, or other unequal aggregations of particles, which would
otherwise detract from the homogeneity of the product and occasion local strains
therein.
I believe that the mode of operation thus brought into play may be explained as
follows:-
The phenomena of elongation and shortening which attend respectively upon
the magnetization and demagnetization of an iron bar, for instance, indicate that
these acts are accompanied by molecular movement throughout the metal, possibly
partial rotation of the individual molecules, or other definite change of position
relatively to one another. Repeated recurrences of such molecular movement, if
produced in a metal, either in a fluid condition or whose particles are in the act of
settling down into a definite structure (such as a mass of crystals) should produce
effects analogous to those which would follow from the mechanical agitation or
shaking of the particles, whilst in an abnormally mobile state, and thus tend
towards the results above referred to as the objects of the process.
I will now proceed to describe the process as an adjunct to, or in connection
with the formation of a casting.
An
In the accompanying drawing, an elementary form of apparatus is shown
adapted to produce a cylindrical casting under the conditions mentioned.
ordinary sand mould, A, (shown in vertical section) having a cavity B, in which
the casting is to be formed, is provided with a coil or helix C of wire, surrounding
said cavity, said wire being insulated by a coating of refractory material, and
embedded in the sand at such a distance from the inner surface of the cavity as to
prevent injurious overheating from the molten metal. The coil is placed in circuit
with a suitable source of electricity, which in the present instance is indicated as a
storage battery D. Interposed in the circuit is an alternator E, whereby the

page_text: polarity of the field produced by the helix may be reversed, such alternator being
worked mechanically or by means of the current itself in any of the well known
modes. The strength of the current and the number of convolutions of the helix
should of course be proportioned to the mass which is to be acted upon within the
field, and to produce the best results, an excess of current should be used beyond
what would be necessary to magnetically saturate a mass of cold iron of equal
size.
Immediately upon the pouring of the metal into the mould, the current is applied
and rapid reversals thereof are produced by means of the alternator. This treat-
ment should be continued during the solidification of the metal, and may be
advantageously protracted after that point, and so long as the internal structure is
susceptible of modification.
I am aware that it has heretofore been proposed to make castings in a permanent
magnetic field, or one which is substantially unvaried, and I do not claim such
treatment. Persistence of uniform magnetic influence would have no substantial
effect upon fluid or solidifying metal, towards attaining either of the above
indicated objects of my process, since it would fail to produce the agitation upon
which the process depends.
I am also aware of the general belief that magnetic influence practically ceases
at a temperature below that of melted iron. The foundation of this view is doubt-
less the fact that one particular phenomenon attendant upon magnetic conditions,
viz. attraction of a mass as a whole, sensibly diminishes in accordance with the
elevation of temperature. It must therefore be understood that in using the
expression "magnetic field" as a convenient term to describe the conduct of my
process, I do not intend to imply that the phenomenon of attraction is necessarily
to be exhibited by the mass of metal within such field, since it is quite possible for
other so-called magnetic phenomena to persist, even though the conditions have
interfered with this particular one; furthermore, it is entirely in harmony with
my theory of operation, that the cooler parts of the mass should exhibit attractive
force in a substantial degree, whilst the hotter parts do not indicate it, and
disturbance of one part relatively to the other be thus produced.
I therefore use the term magnetic field in a sense broad enough to include such
a field of energy as is produced in the neighbourhood of a conducting wire through
which a current of electricity is passing, and without restriction to the ordinary
signification of the word magnetic as necessarily implying the display of attractive
force upon the total mass of material exposed within such field.
In the foregoing description, I have described a storage battery and an alter-
nating device in connection with a helix which surrounds the casting, as an
apparatus adapted to carry out the process, but I wish it to be understood that
such description is typical and not restrictive, and that not only the magnetic field
might be otherwise produced, but that the necessary disturbances therein might be
brought about in various ways, such for instance as by a series of interruptions or
pulsations of the current, as distinguished from a reversal of polarity; by diminishing
the extent of the magnetic field, by moving the metal relatively to the field and
vice versa, or by exposing the metal in a plurality of fields and modifying one or
more of them. So also, instead of the storage battery and alternator above
indicated, an alternating-current dynamo might be employed to energize the field-
producing helix.
I have given the above typical illustration of my invention because it is one
which affords scope for all the useful effects thereof, but it must be understood that
I do not limit my claim to a casting process.
Thus, if the mass of heated metal within the field produced by the helix, C,
above described, had not been a casting made in situ, but were simply a cylinder
of iron or steel, which after being heated to a temperature even below its melting
point (as in ordinary annealing) was subjected to the treatment above described
during the period of cooling, the useful results which depend upon modification of
the general internal structure would be developed in a substantial degree, although,

page_text: of course, these results which depend upon the disengagement of foreign substances
from a fluid mass would be lacking.
I therefore use in my claim, the word "heated" in a sense broad enough to
include, not only a metal which is in a fluid condition, as the result of casting or
otherwise, but also metal whose temperature has been raised in any manner to a
point which renders its particles abnormally mobile.
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 hereinbefore described process of rendering iron, steel and similar metals,
homogeneous, which consists in exposing the metal whilst in a heated condition,
within a magnetic field and repeatedly varying such magnetic field during the cooling
of the exposed metal, substantially as set forth.
O
.
1000
CARPMAEL & Co.,
Agents for the Applicant.