Improvements in the Production of Steel and in the Manufacture of Springs therefrom.
Year: 1892

page_text: Date of Application, 18th July, 1892
Complete Specification Left. 4th Apr., 1893-Accepted. 8th July, 1893
PROVISIONAL SPECIFICATION.
Improvements in the Production of Steel and in the Manufacture of
Springs therefrom.
I LOUIS JACQUES
DIEUDONNÉ HOLTZER of Unicux (Loire) France,
Metallurgist do hereby declare the nature of this invention to be as follows:-
Steel containing a high proportion of silicon has long since been the subject of
metallurgical investigation, but has never hitherto been produced and applied
commercially.
The object of the present invention is to produce a new kind of steel,
characterized by its specific composition and more especially adapted for the
manufacture of springs of all kinds and particularly of railway and other carriage
springs.
Springs made of this steel are capable of supporting without permanent set,
much heavier loads than springs now in use. After tempering they show a tensile
strength of about 150 kilogrammes and an elongation of 10 per cent. Tested by
flexure they give an elastic elongation exceeding 8 millimetres.
This new steel is characterized by the following proportions of silicon, carbon
and manganesc.
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L. J. D. HOLTZER,
By A. M. & Wm. Clark,
53, Chancery Lane, London, Chartered Patent Agents.
COMPLETE SPECIFICATION.
Improvements in the Production of Steel and in the Manufacture of
Springs therefrom.
I LOUIS JACQUES DIEUDONNÉ HOLTZER of Unieux (Loire) France,
Metallurgist 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 :-
Steel containing a high proportion of silicon has long since been the subject of
metallurgical investigation, but has hitherto remained a mere scientific curiosity
and has never been produced on a commercial scale or applied to manufacturing
purposes.
The object of the present invention is to produce a new kind of steel,
characterized by its well defined composition and well suited for industrial
purposes, more especially for the manufacture of springs of all kinds and par-
ticularly of railway and other carriage springs.
Springs made of this steel are capable of supporting, without permanent set,
much heavier loads than springs now in use. After tempering, they shew a tensile

page_text: strength of about 150 kilogrammes per square millimetre (95 tons per square inch)
and an elongation of 10 per cent. Tested by flexion, a bar metre (3 feet
3.4 inches) long gives an elastic elongation exceeding 8 millimetres (0.315 inches).
This new steel is characterized by the following proportions of silicon, carbon,
and manganese :-
The process of manufacture of the new steel remains practically the same as for
ordinary steel, the proportions of its constituent elements being alone varied so as
to obtain the above percentages to which the peculiar properties of the metal
are due.
The steel may be manufactured either in a crucible or in a Martin furnace.
When made in a crucible, the charge is composed of pieces of steel and of ferro-
silicon or silicious pig-iron averaging from twelve to fifteen per cent. of silicon, this
charge being so calculated as to produce a steel of the composition hereinbefore
specified. Fusion is effected in four hours without any difficulty, and the steel
runs freely, is very fluid, and contracts considerably on solidifying.
When a Martin furnace is employed for the manufacture of the steel, to obtain
an output of 9000 kilogrammes, the furnace is charged in the first place with
1200 kilogrammes of grey pig iron and then with 3500 kilogrammes of scrap steel,
after which scrap iron and steel are added in the relative proportions of 3500 kilo-
grammes to about 1200 kilogrammes according to requirements for the purpose of
giving the metal the desired degree of hardness which may be ascertained by
bending test pieces, tempered in water, which should break after bending to 90°.
To the above is then added from 1300 to 1500 kilogrammes of ferro-silicon or
silicious pig containing from twelve to fifteen per cent. silicon, in order to bring
up the percentage of the entire charge to 25 of silicon and 0.6 per cent. of
manganese.
The time required for the fusion of the ferro-silicon is one hour, after which the
charge should be tapped off very hot, as the steel coagulates very quickly.
In the manufacture of springs from this improved steel, the tempering in water
is performed at a higher temperature than that generally adopted-viz.-at a
temperature of from 900° to 1000° C., that is to say between a very bright cherry
red heat and nascent yellow, the peculiar composition of the metal enabling it to
withstand this high temperature without cracking.
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
1. The manufacture of spring steel having substantially the percentage com-
position herein specified.
2. The manufacture of springs of steel of the herein specified composition
tempered at a temperature comprised between the limits specified.
Dated this 4th day of April 1893.
L. J. D. HOLTZER,
By A. M. & Wm. Clark,
53, Chancery Lane, London, Chartered Patent Agents.