Improvements in Tempering-fluid for Treating Steel.
Year: 1890

page_text: Date of Application, 7th Oct., 1890-Accepted, 15th Nov., 1890
COMPLETE SPECIFICATION.
Improvements in Tempering-fluid for Treating Steel.
I, EDMUND TWEEDY, Manufacturer. residing at Danbury, in the County of
Fairfield and State of Connecticut, one of the United States of America, do
hereby declare the nature of my invention, and in what manner the same is to be
performed, to be particularly described and ascertained in and by the following
statement:
The treating fluid comprehended in the invention consists of a mixture of a
diluent, such as water or oil, with a base containing an oxide or a carbonate or both
an oxide or a carbonate of iron, or other metal of the so-called iron group, and an
organic ingredient such as glucose or other carbo-hydrate.
The said mixture may be prepared in a variety of ways. Thus the metallic and
organic ingredients and the diluent may be mixed together at one operation, or the
metallic and organic ingredients may be first compounded together, either with or
without the employment of heat, and the diluent afterwards added. The latter
method is preferred for reasons of convenience. The effectiveness of the mixture
may be somewhat increased by adding to the base a small quantity of sulphuric,
nitric, muriatic or other acid, in the proportion, say, of ten drops of acid to one
ounce of the base but such addition of acid is not indispensable.
In compounding the base the metallic and organic ingredients thereof may be
simply mixed together at atmospheric temperature, in any suitable vessel, or they
may be subjected to various degrees of heat, either during or after the process of
mixing.
The degree of heat employed may be less than is required to cause the ignition of
the organic substance, but it is preferred that it should be sufficient to cause such
ignition, which should be allowed to continue for a short time, when the flame should
be smothered while the mass still retains a pasty condition, and before the whole of
the organic substance is consumed. While the mass is being heated it should be
thoroughly stirred. It is not only desirable to employ heat in the preparation of the
compound, but it will also be found useful to heat the metallic ingredients to redness
and thereby caleine them preparatory to their employment.
When a carbonate is employed in the compound, by the application of heat a portion
of it is converted into an oxide and if the heat is sufficiently high, and the application
is of sufficient duration, the conversion may be complete; but whether in the resultant
mixture the metallic ingredient is wholly a carbonate, or partly a carbonate and
partly an oxide, it is in any case effective for the desired purpose, and within the
present invention.
The proportions of the metallic and organic ingredients which are deemed most
effective are one part by weight of the metallic ingredient to two parts of the organic
ingredient, though considerable variation can be made from these proportions without
materially impairing the efficiency of the compound. The diluent is added in the
proportion, say, of two gallons of the diluent to each ounce of the compound and
the fluid is then ready for use. The presence of a very small quantity of the
compound in the treating bath produces a sensible effect upon the steel treated in it,
which effect appears to be increased about in proportion to the quantity of compound
used, until the proportion of one ounce of the compound to two gallons of the
diluent is reached, beyond which point the addition of more of the compound does not
usually appear to produce any increased effect upon the metal.
In practice the steel, to be treated is usually heated until it presents a dull red
appearance in a moderately dark place, and is then at once plunged into the treating
fluid.
Better results will be attained if the fluid is agitated when used, so as to cause a

page_text: thorough mixture of the ingredients. After the steel is hardened in the fluid the
temper may be "drawn" in the usual manner.
It will be found that the steel so treated will be hardened to much more than tho
usual depth, and that it will possess a remarkable degree of tensile strength and
toughness as compared with that treated by the usual methods of hardening. A lower
degree of heat than is usually employed can be used in hardening by this method,
whereby injury to the metal is avoided.
Carbonates or oxides of manganese, cobalt, or nickel may be substituted for the
carbonate or oxide of iron, but the latter are preferable for their effectiveness and
also for reasons of economy.
A variety of organic substances such as dextrine, molasses, honey, starch-paste, etc.,
may be used as substitutes for the glucose, but the latter is found to be especially
effective.
Having now particularly described and ascertained the nature of my said invon-
tion, and in what manner the same is to be performed, I declaro that what I
claim is :-
1. A tempering fluid for treating steel, the same consisting of a diluent, such as
water or oil, and a base containing a metallic ingredient or ingredients, such as an
oxide or a carbonate, or both an oxide and a carbonate, of a metal of the so-called
iron group, and an organic ingredient such as glucose, with or without a small quantity
of sulphuric or other acid.
2. The herein described process of treating steel, which consists in heating it to a
red heat and then plunging it into a previously prepared bath consisting of a diluent
such as water or oil, and a base containing a metallic ingredient or ingredients, such
as an oxide or a carbonate, or both an oxide and a carbonate, of a metal of the so-
called iron group, and an organic ingredient such as glucose, either with or without a
small quantity of sulphuric or other acid, substantially as set forth.
Dated this Gth day of October 1890.
H. B. BARLOW,
17, St. Ann's Square, Manchester, Agent for Applicant.