IMPROVEMENTS IN MANUFACTURE AND TREATMENT OF SELF HARDENING STEEL
Year: 1884

page_text: I ROBERT HADFIELD of Sheffield in the County of York Steel Manufacturer
do hereby declare the nature of my invention for IMPROVEMENTS IN
MANUFACTURE AND TREATMENT OF SELF HARDENING STEEL to be as follows :—
THE
The object of this invention is to produce an improved self-hardening steel,
which is naturally hard, either in its cast or forged state at a greatly reduced cost.
Hitherto it has been considered absolutely indispensable to use expensive foreign
and other high class irons in conjunction with high per centages of tungsten and
other costly raw materials for the production of self-hardening steel thereby
restricting its use, owing to its costliness.
Now my invention consists firstly in substituting for such expensive foreign
and other high class irons English or other irons, or English or other scrap, either
of iron or steel, or of both combined; and Secondly, In entirely dispensing with
the use of tungsten and substituting therefor manganese which I add to the
materials under treatment in proportions of not less than 2% up to, but not
including 7% according to the quality of steel required to be produced while
preferably I keep the carbon comparitively low.
I am aware that manganese has been used heretofore but the per centage
employed has rarely exceeded 14% whilo ordinarily a very little over half this
amount is employed.
By my invention I obtain a self hardening steel which altho' extremely hard
when cold, yet works quite mild; and which when being reduced allows of a much
higher degree of heat being used than heretofore without deteriorating from its
quality thus facilitating working and effecting considerable econoiny.
It is also very free from impurities, such as dirt and slag and from other defects,
such as honeycombs, whilst the presence of Silicon does not interfere with its self-
hardening properties.
Such improved self-hardening steel may be manufactured by any steel manu-
facturing process.

page_text: Hardening Steel.
I, ROBERT HADFIELD of 33 Southampton Buildings, Holborn London do hereby
declare the nature of my invention for IMPROVEMENTS IN THE MANUFACTURE
AND TREATMENT OF SELF HARDENING STEEL, and in what manner the same is to
be performed, to be particularly, described and ascertained in and by the following
statement:
The object of this invention is to produce an improved self hardening steel that
is naturally hard either in its cast or forged state at a comparatively low cost.
Hitherto it has been considered absolutely indispensable to use expensive foreign
and other high class irons in conjunction with tungsten or its kindred alloys in
the production of self hardening steel thus restricting its use owing to its
costliness.
Now my invention consists in substituting for such expensive foreign and other
high class irons English or other pig iron either wholly or to a great extent
decarbonised refined or otherwise treated or English or other scrap iron or steel
scrap, or both combined, or steel produced by any of the steel making processes
and in entirely dispensing with the use of tungsten and its kindred alloys and
substituting therefor manganese which I add to the materials under treatment in
the form of any of the alloys of ferro-manganese used in the manufacture and
production of steel such as ferro-manganese-silicon or spiegel.
I use such alloys either separately or together and in such proportions as to
obtain in the resultant product a per centage of manganese varying from 21 (two
and a half) per cent up to about 7 (seven)-per cent while preferably I keep the
carbon low.
The exact proportions or quantities to be employed of such alloys are governed
and regulated 1 By the per centage of manganese contained therein-2ndy By
the character of the materials under treatment and 3rdy By the quality of the
steel required to be produced, such quality being determined by the purpose or
purposes to which it is to be applied-But I have found that where the maximum
degree of hardness is essential in the resultant product such alloys may be
beneficially used in proportions sufficient to obtain in such product a per centage of
manganese varying from 21 per cent up to about 5 per cent while where a lesser
degree of hardness is required.
I bave found that it is beneficial to use such alloys in proportions sufficient to
produce in the resultant product a per centage of manganese varying from about
5 per cent up to about 7 per cent.
The alloy or alloys employed are either melted with the materials under
treatment or are added thereto when both are in a state of fusion and the resultant
product may either be run into moulds and shapes as with ordinary steel and iron
castings Or it may be run into ingots or other shapes and may be subsequently
hammered forged rolled or otherwise reduced into bars plates or other forms as
desired,

page_text: I would here observe that I am aware that manganese has been used heretofore
in the production of self hardening and other steels but only in connection with
tungsten and its kindred alloys and also with expensive or comparatively expensive
materials as compared with the materials employed by me as herein before
mentioned At the same time the per centage employed has rarely exceeded 11 per
cent, while ordinarily a very little over half this amount has been employed.
As a striking proof of the difference between my improved self hardening steel
and the self hardening steel hitherto produced I may mention that numerous
analyses have shewn the latter to contain from 1% up to 2% of carbon whereas
my improved self hardening steel can be produced with even one half per cent of
carbon.
By my invention I obtain a self hardening steel which although extremely hard
when cold yet works quite mild, and which when being reduced allows of a much
higher degree of heat being used than heretofore without deteriorating from its
quality thus facilitating working and effecting a considerable economy It is also
very free from impurities such as dirt and slag owing to the increased purifying
properties of the manganese when used in the per centages herein before indicated
and likewise from other defects such as honeycombs whilst the presence of Silicon
does not interfere with its self hardening properties.
Such improved self hardening steel may be manufactured by any of the steel
manufacturing processes.
Having now particularly described and ascertained the nature of my said
invention and in what manner the same is to be performed I declare that what
I claim is
1° Employing English or other pig iron either wholly or to a great extent
decarbonised refined or otherwise treated or English or other scrap iron or steel
scrap or both combined or steel melted and produced by any of the steel making
processes in combination with manganese the latter being used substantially in the
manner and proportions hereinbefore specified for the production or manufacture
of an improved self hardening steel.
2° In the production of such improved self hardening steel the substituting
manganese for tungsten and its kindred alloys substantially in the manner and
proportions and for the purposes hereinbefore specified.
Babad thin Reh
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