An Improved Method of Toughening Manganese Steel Castings.
Year: 1896

page_text: Date of Application, 30th May, 1896
Complete Specification Left, 26th Feb., 1897-Accepted. 17th Apr.. 1897
SIONAL SPECIFICATION.
An Improved Method of Toughening Manganese Steel Castings.
I, ROBERT ABBOTT HADFIELD, of The Grove, Endcliffe Vale Road, Sheffield,
in the County of York, Steel Manufacturer, do hereby declare the nature of this
invention to be as follows:-
As is well known manganese steel castings have been toughened by heating them
to a dull red and then plunging them into cold water, but this process is open to
objection owing to the resulting liability to production in the heating process of
internal fractures such as cannot be detected on the surface of the castings.
Now my present invention has for object to prevent or mitigate this evil, to which
end, according thereto after the manganese steel castings have been cleaned of any
excess of sand from the moulds, they are put into the heating furnace in which
they are to be heated before the fire is started and while the furnace is still cold,
then a small fire is started in the furnace and heat is thereby applied to the castings
very gradually, the first heating being conducted at a very slow rate this rate.
depending upon the thickness of the castings, the thicker the casting, the slower.
the rate of heating and this being carried on until the castings have become visibly
red, after which the heating may be carried on at a more rapid or moderately rapid
rate until the desired temperature (say an orange heat) is reached, after which the
castings are removed from the furnace as quickly as possible and plunged into cold
water, thus completing the toughening process. In carrying out my invention,
for example the rate of heating might be such for thick castings, say those from:
2" to 4" thick in their thickest parts, that one hour would be consumed in raising
the casting to a temperature of about 400 degrees Fahr.; in two hours the casting
might reach, say, 800 degrees Fahr. and in three hours say 1200 Fahr., after which
the casting, heated at this slow rate, will have become visibly red and the heating
may be carried on at a more rapid or moderately rapid rate, as aforesaid-say up to
about 1700 degrees Fabr. (say orange red).
Dated this 20th day of May 1906
An Improved Method of Toughening Manganese Steel Castings.
I, ROBERT ABBOTT HADFIELD, of The Grove, Endcliffe Vale Road, Sheffield,
in the County of York, Steel Manufacturer, 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:-
As is well known manganese steel castings have been toughened by heating them
to a dull red and then plunging them into cold water, but this process is open to

page_text: objection owing to the resulting liability to production in the heating process of
internal fractures such as cannot be detected on the surface of the castings.
Now my present invention has for object to prevent or mitigate this evil, to which
end, according thereto the heating of the manganese steel castings is commenced
in the furnace when it is cold or practically cold, and the castings are heated very
gradually especially during the earlier portion of the heating process and finally
after they have been thus brought up to the desired heat they are plunged into
cold water.
In actual practice after the manganese steel castings have been cleaned of any
excess of sand from the moulds they are put into the heating furnace in which they
are to be heated before the fire is started and while the furnace is still cold.
A small fire is then started in the furnace and heat is thereby applied to the castings
very gradually. The first heating must be conducted at a very slow rate. This
rate depends upon the, thickness of the castings, that is to say, the thicker the
casting the slower must be the rate of heating. By way of illustration I may say
that the rate of heating should be such for thick castings, say those from one inch
and a half to two inches thick in their thickest parts, that one hour would be
consumed in raising the casting to a heat of about 400 deg. Fahrenheit. In two
hours the casting may reach say 800 degrees Fahrenheit and in three hours
1200 degrees Fahrenheit. After the casting, heated at this slow rate, has become
visibly red, I believe there is no further danger of internal rupture, and the heating
may then be carried on at a more rapid or moderately rapid rate until the desired
temperature is reached, say about 1,700 degrees Fahrenheit, or, in other words,
orange heat. The castings are then taken from the furnace as quickly as possible
and at once plunged into a tank of cold water, by which the toughening process is
completed.
Having now particularly described and ascertained the nature of the said inven-
tion and in what manner the same is to be performed I declare that what I
claim is :-
The hereinabove described improved method of toughening manganese steel
castings, according to which the heating is commenced with the furnace at a low
temperature, heat is applied very gradually until the castings are visibly red, thence-
forward the application of heat is continued until a suitably high temperature such
as an orange heat has been attained and finally the castings are plunged in cold
water, substantially as described.
Inn CORN UITS
In the VIROR
day
February
For the Applicant,
W. LLOYD WISE,
46 Lincoln's Inn Fields, London, W.C., Chartered Patent Agent.