IMPROVEMENTS IN THE MANUFACTURE OF STEEL
Year: 1869

page_text: LETTERS PATENT to Julius Baur, of New York, in the State of
New York and United States of America, Practical Chemist, for
the Invention of "IMPROVEMENTS IN THE MANUFACTURE OF STEEL."
Sealed the 9th October 1869, and dated the 21st August 1869.

page_text: in what manner the same is to be performed, in and by the following
statement
The nature of these improvements consists,-
First. In a method herein-after to be described of making steel in
crucibles or any other suitable furnace or vessel by alloying or com-
bining metallic chromium with metallic iron or other steel making
material in such manner that chromium in a metallic state shall be
present in the finished product to impart valuable properties thereto.
And, second. In making steel in crucibles or otherwise as stated by so
alloying or combining the metallic chromium with the metallic iron
or steel making material that the finished product shall derive its
requisite steely properties solely from the metallic chromium present in
it, and not from carbon or carbonaceous matter.
Steel made by these processes is far superior to other steel, and my
practical experience with them has tended to convince me that this is
due to the less aflimnity which oxygen has for chromium than it has for
carbon. From this it follows that the unavoidable exposure more or less
to the atmosphere and often to oxygen in some other form, to which in
all processes the steel making materials are always subjected during the
manufacture must necessarily cause much less chromium if that be used
to be removed or affected so as to lead to injury or lack of uniformity in
the product than it will carbon, if carbon be used. Hence the maker of
steel by the ordinary methods is frequently unable to judge what
per-centage of carbon will be found in the finished metal, because he
cannot know what proportion of that which he puts into his crucibles
or other vessels will be carried off by contact with oxygen during the
manufacture. This
appears to be an important cause of the want of
uniformity and many other defects so frequently observed in steel made
in the usual way. But my chromium processes are practically wholly
unaffected by oxygen and therefore secure the most perfect uniformity
and certainty of product.
In carrying out these Inventions I employ chrome ore or oxide of
chrome, and I so manage the reduction of this chrome ore or chrome
oxide, or as it may properly be termed, in view of the present Inventions,
the combination of the chromium with the steel making iron, that the
operation of reduction of the ore to the metallic state shall include or

page_text: be simultaneously attended by the combination of the chromium in the
metallic form with the iron employed for conversion to steel, and by
this means I make products which are of the very, highest character,
possessing great tenacity and toughness and having practically, almost
perfect uniformity.
In practice I have secured successful results by taking to every fifty,
pounds or thereabouts or in that proportion of the iron designed for
steel, say, three pounds of chrome ore as it usually comes, and one pound
of carbon or carbonaceous matter in any suitable form and melting the
whole together at one operation in a crucible in the ordinary steel
melting furnace in the manner commonly followed in making crucible
steel. The melting may however, if preferred, be performed in a suitable
The above mixture
gas furnace, or in any other convenient apparatus.
will produce a most excellent quality of what is termed * high steel,"
and if I desire to make steel of a lower grade I employ with the above
stated proportions of iron and chrome ore twelve ounces or thereabouts
of the carbon or carbonaceous matter, and proceed as described, or for
a still lower grade 1 may diminish the carbon or carbonaceous matter to
eight ounces or thereabouts, proceeding in other respects as already set
forth. The product thus made will when run into ingots in the usual
way he found to be a pure uniform metal possessing all the charac-
teristics of the very finest quality of steel, and it will be observed that it
is produced at a single operation by what may be termed a simultaneous
reduction and combination with the steel making iron of the chrome
which is the foundation of the metal. In respect however of the second
branch of these improvements in which the metallic chromium in the
finished product is employed instead of carbon to impart the requisite
steely properties to the metal, I wish it to be understood that although
I contemplate the employment of carbonaceous matter as stated during
the operation of melting the materials to make the steel, I do not do it in
order to secure for the product any effect from such carbon. Nor does
my process operate in any such way or secure any such effect. The
carbon is used merely to accomplish the reduction of the chrome ore to
metallic chromium during the melting, so that it may alloy with the
steel making material, and that is the sole function which it performs
in the operation. Therefore when the proportion of the carbon or
carbonaceous matter is varied as above stated in making steel of the
different grades which have been mentioned, it must be understood that

page_text: it is only done because it is the reducing agent for the chromium, and
consequently since the greater or less proportion of alloying chromium
which exists in the metallic form in combination with the iron in the
finished product is the only thing in the second part of my process
which determines the degree of hardness of the steel and its character
or grade, the carbon must or preferably should be increased or diminished
according as the proportion of chrome ore mixed with the iron to be
converted into steel is increased or diminished, for the more chrome ore
thus mixed the more carbon will be required to reduce the chromium
to the metallic form in order that it may alloy with the iron, and the
less chrome ore the less carbon. Hence in the three examples herein-
before given although the proportion of chrome ore is made the same in
all, the theory upon which the examples proceed is that only so much of the
chrome ore as stated in the examples as will be reduced by the proportion
of carbonaceous matter also stated in each example respectively will be
converted into the metallic form, and enter into an alloy with the iron to
make the finished steel. Thus in the first example where one pound
(sixteen ounces) of carbon is mentioned substantially the entire three
pounds of chrome ore given in the example will be reduced to the metallic
state by this carbon, thereby imparting to the finished steel, the qualities
mentioned under that example in the second example there being but
twelve ounces of the reducing agent employed something less than the
whole three pounds of chrome ore will be reduced, thus producing the
modification of the product stated for that example, and in the third
example the eight ounces of carbon will reduce still less of the three
pounds of chrome ore, thereby causing a still further modification of
the product.
If desired however the following examples and method of procedure
may be adopted-For a "high" steel suitable for instance for turning
tools and similar uses, take to every one hundred pounds of proper steel
making iron, such as Peru or Danemora iron, three pounds of chrome
ore and as much carbon or carbonaceous matter as may be required,
according to the quality of the latter to reduce this amount of chrome
ore to the metallic state, proceeding in all other respects as above
directed. For a lower grade of steel adapted to taps, dies, etc., take to
every one hundred pounds of the steel making iron of proper quality
one pound of chrome ore and sufficient carbon to reduce the latter to
the metallic form, proceeding otherwise as before. For any other grades

page_text: or variations desired in the product between these two examples, take
to the one hundred pounds of iron any suitable amount of chrome ore
between the one pound and the three pounds of the examples according
to the character of product required by the operator, and employ with
it such amount of carbon as will suffice to reduce to the metallic state
the quantity of chrome ore so selected.
In many cases, as, for instance, when "Bessemer scrap
contains a larger than ordinary per-centage of carbon or
" or iron which
blister steel"
is employed for conversion into steel, by my process the carbon thus
existing in the same will be found sufficient in quantity to reduce the
chrome ore to the metallic state without the addition of any more carbon
for that purpose.
In these cases which in practice will readily be
distinguished by the operator, the use of such additional carbon may
therefore be dispensed with.
From the foregoing remarks it will be seen that the carbon used as.
described in this Specification need not and, so far as respects the second
part of my improvements, does not in any way influence or determine
the character or qualities of the steel when finished, and when finished it
does not possess the qualities of carbon steel as distinguished from the
chromium steel" manufactured by my previous Inventions, but it has
only the well known characteristics of such chromium steel; it will
therefore be obvious that it is the chromium and the chromium alone
which imparts to it its distinctive features and determines its character.
"
I may remark that in carrying out these Inventions, I prefer to
employ the chrome ore in the form of small grains, say about the size
of ordinary writing sand, and the carbon in the form of pure hard char-
coal reduced to grains of about the size of barley. I do not find it
necessary to use any flux but any suitable one may be employed if desired.
I wish it however to be understood that I do not limit myself to the
specific proportions of steel making iron chrome ore and reducing carbon
or carbonaceous matter above referred to, as these may be varied without
departing from my Inventions, and the foregoing examples are given
only as those mixtures and variations which I have found preferable.
I am aware that chromium has been alloyed with iron merely for
scientific or laboratory experiment, and I am also aware of the English
Letters Patent which have been granted to Robert Mushet, in which he
has spoken of the use of chrome ore or oxide of chromium with other
substances in making steel. But limited, accurate, and specific rules of

page_text: practical application for accomplishing what is herein described have
never before been made known, and my Inventions are clearly dis-
tinguishable from anything which preceded them in this, that it has not
heretofore been supposed that steel, or as perhaps it should be termed a
substitute for steel, could be made in a practical way, and for practical
and valuable use in the arts by alloying metallic chromium with metallic
iron, nor has it been known that by so doing this, that no carbon or sub-
stantially no more than existed in the material before it was converted
into steel, shall be present in the finished product, the properties required
in steel and recognized as constituting the difference between steel and
iron, and for the imparting or production of which carbon usually with
other substances, such as manganese, etc., has hitherto been supposed to
be essential, can be given to the product solely and entirely by the alloy
in it of the metallic chromium without the employment in any degree
whatever of carbon or any kind of carbonaceous matter to affect the
finished metal. Hence no process in which chrome ore or oxide of
chrome operates, either designedly or not, only as a flux is here claimed
or is regarded by me as possessing importance. It is essential to my
Inventions that the chromium in a metallic state should alloy or combine
with the steel making iron or material in a metallic state and be
present in the finished metal, and the product of my processes is such
an alloy or combination of metallic chromium and metallic iron, and
the presence of the metallic chromium in it may be demonstrated by
proper tests.
In the product of the second branch of my process 1
aim to have no carbon or carbonaceous matter whatever, and in practice
there is none in it except only the insignificant amount which existed
in the bar iron or other steel making material before it was converted
into the steel or alloy mentioned. Furthermore, when in practising this
part of my process use is made of new crucibles or **
pots" or crucibles
containing carbon which may be imparted to the steel making materials
during the operation of melting I make allowance for this carbon and
employ so much the less for the reduction of the chrome ore.
Having thus fully described my said Invention, I claim,-
or
First. The above-described process of making steel by combining
alloying metallic chromium with metallic iron so that the metallic
chromium shall be present in the finished product substantially as set
forth,

page_text: Second. The foregoing process of making steel, or what may be termed,
a substitute for steel, by combining or alloying metallic chromium witli
metallic iron in such a manner that the metallic chromium shall be
present in the finished product, and shall be the only agent which
imparts to such product the qualities of steel, substantially as described.
In witness whereof, I, the said Julius Baur, have hereunto set my
hand and seal, this Second day of August, in the year of our
Lord One thousand eight hundred and sixty-nine.
JULIUS BAUR. (L.S.)