Improvements in and Apparatus for the Manufacture of Soft Back Steel.
Year: 1889

page_text: Date of Application, 13th Sept., 1889-Accepted, 2nd Nov., 1889
COMPLETE SPECIFICATION.
Improvements in and Apparatus for the Manufacture of Soft Back
Steel.
I, MARTIN ARMSTRONG HOWELL, Junior, of 70, Basinghall Street, in the City of
London, Gentleman, do hereby declare the nature of this invention and in what
manner the same is to be performed, to be particularly described and ascertained in
and by the following statement:-
This invention relates to the manufacture of plates or flat bars of steel having one
side highly carbonised and the opposite side practically free from carbon which after
hardening present a so called soft back steel which renders it less liable to break or
crack while hardening and more tenacious when in use where great rotary force or
heavy blows or strains are required as in many branches of mechanical operations, and
to the apparatus required therein.
In order to carry out this invention I take plates or flat bars of low carbon or soft
steel or fine iron in pairs of equal size place them back to back having a film of clay
or other refractory material interlaid between them. I then clamp or wire them
together and place the several pairs in a receptacle or flask stratified between layers of
granulated charcoal the said flask being placed in the muffle of a furnace in a hori-
zontal position, the said flask is provided with an inlet tube and cock at one end
thereof and an outlet cock at the other end to ensure a free circulation of the necessary
gases and to enable the operator to regulate the flow of such gases, pressure being
applied at the gas holder communicating therewith.
In a former patent granted to Henry Harris Lake numbered 1203 and dated
6th March 1883 (being a communication for myself) I described a receptacle or
flask similar to that I now propose to employ but having the inlet and outlet cocks at
the top and being placed in the furnace vertically instead of horizontally according to
this invention which former method I have found to be inoperative as by driving the
gas in at one cock instead of permeating the mass to the bottom and returning
it simply escaped at the outlet cock and gave no good results and had to be
abandoned.
I do not confine myself to any particular shape of flask as different shapes are
required to conform to that of the articles and sizes of plates treated some beinground
and some flat but in all cases the flask is provided with an airtight head or cover that
will permit the contents to be kept sealed hermetically, the main object being to
exclude air and keep a circulation of gas throughout during the heat.
One end of the flask is connected (at its stop cock) with a tube containing
practically pure hydrocarbon vapour. When the heat of the furnace has raised the
temperature of the said flask to a low red heat I drive in a current of hydrocarbon
which displaces and drives out all traces of oxygen or other objectionable vapours at
the open cock at the opposite end of the receptacle when the heat reaches the cherry
red stage the flow of the gas is diminished to a simple motion of the current until the
metal has taken up enough carbon which varies with the thickness of the plates or
bars and the depth of carbon required.
When the work is complete the cocks are closed the flask disconnected from the gas
tube and withdrawn and allowed to cool in an atmosphere of hydrocarbon and another
similar flask may be placed in the same position and the work continued.
When cooled off the said receptacle is opened and the plates are taken out and
forged hardened and tempered in the usual well known way.

page_text: Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed I declare that what I
claim is :-
1st. Manufacturing soft back steel substantially as set forth.
2nd. The improvements inapparatus for manufacturing softback steel substantially
as set forth.
Dated this.13th day of September 1889.
BROWNE & Co.,
9 & 10, Southampton Buildings, Holborn, W.C., Agents for the Applicant.