Improvements in and Means for Tempering and Hardening Metals.
Year: 1892

page_text: I
COMPLETE SPECIFICATION.
Improvements in and Means for Tempering and Hardening Metals.
I, JOSEPH STUBS DURNING, a citizen of the United States of America, residing
at Emsworth, in the County of Allegheny and State of Pennsylvania, in the said
United States of America, Blacksmith, do hereby declare the nature of this inven
tion and in what manner the same is to be performed to be particularly described
and ascertained in and by the following statement:-
My invention relates to the tempering and hardening of metals, and relates more
particularly to the tempering and hardening of malleable cast-iron, although I
claim the application of it to all metals to which the invention may be found
applicable.
The object of my invention is to provide a process by which malleable cast-iron
or any other suitable metals may be tempered and hardened so as to possess the
temper and hardness of high grades of tool steel, and after subjection to the
process may be tempered by heating and submersion, in substantially the same
manner as such steel.
As above stated, I include within the scope of my invention any metals to which
it may be applicable; but for the purpose of illustration I will describe the process
as applied to mallcable cast-iron as experience has proven its perfect adaptability
to the tempering and hardening of that metal.
It is well known that malleable cast-iron possesses special properties of softness
and flexibility combined with a degree of toughness which makes it very suitable
for certain grades of castings requiring such properties; but on account of its
property of softness is unfit for purposes of manufacturing articles requiring tempér
and hardness. By this process this metal, which would be far preferable for many
articles of manufacture if only certain parts thereof could be hardened, can be
hardened at these points and possess the properties of high-carbon steel.
The process is as follows: I take a piece of malleable cast-iron of the desired
shape and coat it at all the points desired to be hardened with a composition formed
of one pound of rye flour, ten pounds of prussiate of potash, and a liquid obtained
by boiling in sixty gallons of water twelve pounds of the leaves, sprouts or roots of
the plant known as the "American Laurel," a name given to an evergreen shrub of
the genus Kalmia. Sufficient of the liquid so obtained is added to the flour and
prussiate of potash to bring the mixture to the consistency of a paste.
This paste
is then applied by means of a brush or in other suitable manner to the surface of
the malleable cast-iron or to the part or parts thereof to be tempered. The metal
is then heated to the proper temperature, generally a shade higher than a cherry-
red. The metal is then taken in this highly-heated condition and plunged into a
vessel containing a liquid obtained from the laurel, as above described. The metal
is allowed to remain in the liquid until it is cooled off, a time varying according to
the thickness of the metal. It will be found upon withdrawing the metal that the
parts thereof coated and subjected to the treatment above described will have
acquired the properties of steel of high carbon. The metal, which was formerly
tough, soft, and malleable, has become tempered and hardened. A further
peculiarity and merit is that upon reheating the part or parts thus tempered it is
not reduced to its original state-malleable iron-but upon plunging again in its
heated state into ordinary water, as in tempering steel, the parts treated in accord-
ance with the process not only retain their hardness, but may be even more highly
tempered and hardened, according to the treatment, which is similar to the treat-
ment of tempering cast-steel.
It is readily apparent that the process can be applied with special advantages to
articles which can be more readily formed of malleable cast-iron, yet whose

page_text: manufacture from such metal has been precluded heretofore because, as the
malleable cast-iron was soft, the bearing points on such articles could not withstand
the wear to which they would be subjected. By this process this difficulty has
been overcome, as such bearing points may be hardened in the manner above
described to any desired degree. For example, in the manufacture of a horse-shoe,
it will be seen to possess marked advantages, the shoe being cast from malleable
iron a more perfect shoe can be obtained, while the calks and toes when treated by
this process will possess a degree of hardness adapted to withstand the severe wear
to which they are subjected. In the composition and liquid employed in the process
I claim the chemical equivalents adapted to produce the same results, but do not.
desire to limit myself to the exact proportion of ingredients as above given as these
may be varied without departing from the nature of my invention.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed, declare that what I
claim, is :-
1. The herein-described process of tempering and hardening metals, consisting in
coating the surface of the metals with a mixture composed of flour, prussiate of
potash, and a liquid concoction from the laurel plant, heating said metal, and
plunging it when highly heated into liquid, substantially as described.
2. The herein-described process of tempering and hardening metals, consisting in
coating the surface of the metal with a mixture composed of flour, prussiate of
potash, and a liquid concoction from the laurel plant, heating the metal, and
plunging it when highly heated into such liquid concoction, substantially as
described.
3. A composition for tempering and hardening metals, containing a liquid con-
coction from the laurel plant, substantially as described.
4. A composition for tempering and hardening metals, containing flour, prussiate
of potash, and a liquid concoction from the laurel plant, substantially as described.
1000
JENSEN & SON,
77, Chancery Lane, London, W.C., Patent Agents.
JENSEN & SON,
77, Chancery Lane, London, W.C., Patent Agents.