IMPROVEMENTS IN THE MANUFACTURE OF MILD STEEL OR HOMOGENEOUS IRON, AND IN THE TREATMENT OF THE SAME FOR VARIOUS USEFUL PURPOSES
Year: 1877

page_text: PROVISIONAL SPECIFICATION left by Richard Howson at the Office of the
Commissioners of Patents on the 18th May 1877.
RICHARD HOWSON, of Middlesbrough-on-Tees, in the North Riding of the
County of York, Engineer.. "IMPROVEMENTS IN THE MANUFACTURE OF MILD STEEL
OR HOMOGENEOUS IRON, AND IN THE TREATMENT OF THE SAME FOR VARIOUS USEFUL
PURPOSES."
My Invention has reference to that process of manufacturing steel or homogeneous
iron, which consists of first puddling pig iron, and afterwards melting the puddled
product in a Siemens', or other furnace, either along with pig iron or without it,
but with the addition of spiegel eisen or ferromanganese. This process is so well
known and understood that it is unnecessary to describe it. There has, however,
always been a difficulty in using pig iron of the cheaper brands, such as those which
contain a high per-centage of phosphorus.
The first part of my Invention relates to the puddling part of the process alone,
and consists in a method whereby I am enabled to utilize such inferior brands to
the total or almost total exclusion of more expensive ones. In effecting this end I
discard the ordinary puddling furnace, and use a revolving furnace which is capable
of producing an intermittent flame, and I prefer to use the construction of furnace
described by Samuel Godfrey and Richard Howson in their Patents dated Decem-
ber 20th 1875, No. 1414, and January 29th 1877, No. 383, respectively, although
I do not confine myself to this particular construction, provided the source of
heat can be rendered intermittent and can be regulated at will without producing
much smoke. Being thus furnished with a furnace adapted to the purpose, I
employ a method of puddling distinguished from that usually practiced in the
manufacture of wrought iron, in this respect that I work with a generally lower
temperature and with an intermittent flaine.
The pig iron having been melted in a separate furnace or in the revolving furnace
itself, I commence the operation of puddling without any flame at all, or with as
little as possible, the inside of the revolving barrel however having been previously
heated.
The oxidation of the silicon, phosphorus, and carbon contained in the iron gradually
proceeds by contact with the fettling as the furnace revolves, and by means of this
oxidation the temperature increases of itself without any extraneous aid, 'Whẹn the

page_text: metal has thus reached the stage of commencing to boil, I allow the flame to play
upon it, and increase the heat towards-the end of the operation, but the highest
temperature reached need not be greater than that which enables the converted iron
to adhere together and form into a ball.
By following out this process, the greater part of the impurities contained in the
metal will be found to be eliminated, but the wrought iron will still retain a small
amount of phosphorus, which it is intended should remain, and which may vary
from one-tenth to five-tenths per cent. It may also retain more or less carbon, but
it is desirable that the carbon should be generally low, and the lower in proportion as
the phosphorus is high. I therefore allow the ball after it is formed to romain
some time longer in the furnace by which means the remaining carbon becomes
gradually oxidized by the agency of the contained cinder. When now the ball is
examined, if the oxidation is not complete enough, a lambent flame will appear on
the surface, and in this case I allow it to remain still longer in the furnace, until tho
flames have entirely disappeared. The ball may now be removed and squeezed or
hammered in order to remove the contained cinder, and it is ready to be transferred
at once to the melting furnace.
Instead of being kept in the revolving furnace it may be sometimes convenient
to place the puddled balls in a separate stationary furnace, in which thoy may bo
kept hot, until a melting furnace is ready for their reception. Such supplementary
furnace may be also supplied with a bath of comparatively pure cinder, into which
the balls may be immersed.
It will be readily understood that it is not always possible to insure a fixed per-
centage of phosphorus in the steel, since the operation of puddling has some degree
of uncertainty in it. For many purposes it is sufficiently exact, but for others a
greater uniformity is desirable. In such enses instead of transferring the blooms
while in a hot state to the melting furnace, I allow them to get cold and then break
them into two or more pieces. By examining the fracture, a practiced eye will
easily distinguish those blooms which contain much phosphorus from those which
contain less, and by this method the blooms may be classified into groups according
to the quality of the steel to which they are respectively adapted.
I have hitherto spoken of the puddled balls as having to be hammered or
squeezed, in order to press out the contained cinder, before they are transferred to
the melting furnace, but I have ascertained that it is possible to melt the balls direct,
without having the cinder pressed out. By this method the quality of the steel is
not materially impaired, but the presence of much cinder has the effect of damaging
the hearth and jambs of the melting furnace, owing to the great affinity which
oxide of iron has for silica, whereby the bricks and gannister lining are fluxed and
rapidly destroyed. It follows, therefore, that the smaller the balls are, that is to
say, the greater number there are for a given weight of metal, the less is the
quantity of contained cinder, and consequently the smaller is the damage which
accrues from its presence. I have, moreover, ascertained that by following out, at
or about the final stage, the above described method of puddling, at a comparatively
low temperature, it is possible to bring out of the puddling furnace an indefinite
number of balls instead of only one, even to the extent of what may be described as
granulated wrought iron or steel, and this is the best condition for the metal to be
in when it is intended to be melted direct without hammering or squeezing.
By means of the method or methods which I have thus described of manipulation
in the revolving furnace, and afterwards melting the product in the manner well
known, I am enabled to produce what may be called a phosphoric steel of a mild
nature, but possessing great strength and malleability, and at a very cheap rate.
My Invention relates, secondly, to the treatment of such steel immediately after
it has been hammered, rolled, forged, or cast, and before it has become cold.
In the year 1868 I discovered that when steel containing less than five-tenths per
cent. of carbon is plunged into water at a red heat it no longer hardens in the sainė
manner as ordinary steel. Its elasticity is diminished, but at the same time its
tenacity and resistance to flexure is much increased.

page_text: I have recently discovered that phosphoric steel made by the method or methods
above described possesses a similar property in such a degree as to render its appli-
ention useful for a variety of purposes. Whenever, therefore, I wish to confer
additional strength on articles manufactured by the above described processes, I
effect the purposo by plunging them into water just at the point where they leave
the hammer, the rolls, or the mould, and before they have time to get cold.