ALLOY STEEL

ACIER ALLIE

English Abstract

ALLOY STEEL
Abstract of the Disclosure
There is provided a high strength alloy steel
comprising a vanadium alloyed steel normalized at
a temperature above 927°C.

Claims

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The embodiments of the invention in which an exclusive
property or privilege is claimed are defined as follows:
1. A method of forming a high strength, high carbon,
alloy steel comprising the steps of alloying a vanadium
steel consisting of about 0.50 to 0.80% carbon, about
0.60 to 0.85% manganese, nil to about 0.050% phosphorous,
nil to about 0.050% sulfur, about 0.15 to 0.50% silicon,
about 0.06 to about 0.25% vanadium, and the balance iron
with residual impurities in ordinary amounts; and nor-
malizing said steel at above 927°C.
2. A method of forming a high strength alloy steel
as set forth in Claim 1 wherein said normalizing is in
the range of 982°C to 1149°C.
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Description

o733Z~
~ ALLOY STEEL
; This invention relates to high strength alloy steels
and more particularly to a high strength alloy steel
suitable for casting into railroad car wheels and the ,~ !
like.
There has been a long felt need ~or steel alloy -~
having a greater strength and suitable properties for cast- :
i~g into railroad car wheels and the li~e. Heretofore,
experiments with vanadium alloy steels have not been
entirely satis~actory, in that the results have not been
uniformly consistent. Likewise, normalizing o standard
carbon alloy steels without the vanadium at temperatures
above 927C has not produced significantly better results.
The primary object of the present invention is to provide
an improved method of forming a high strength vanadium
alloyed steel normalized in an optim~n range. :
In accordance with the present invention, it has .
been ~ound that a superior high strength alloy steel is
formed when a vanadium alloyed steel is normalized at
a temperature above 927C.
It has been discovered according to the present
invention that a steel alloy treated in the molten state
with vanadium and normalized at a temperature above
,
, . . ..

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927C provides an alloy suitable for the manufacture of
castings and other wrought articles having excellen~
yield strength and other characteristics w~lich make it
desirable for the casting of railroad car wheels and
the like.
The alloy steel of this invention may comprise
broadly the following composition:
Component Precent by Weight
Carbon abou~ 0.50 to 0.80%
Manganese about 0.60 to 0.85%
Phosphorous nil to about 0.050%
Sul~ur nil to about 0~050%
Silicon about 0.15 to 0.50%
Vanadium 0.06 to about 0.25%
Iron Balance wlth residual im~
purities in ordinary amounts
The presence o~ vanadium coupled with normalizing
is critical and must be maintained substantially within
the range set out above. The alloy must have had su~-
ficient vanadium added to the molten metal to provide a
residue of at least 0.06% vanadium in the alloy thereby
producing the desirable characteristics of high resis-
tance to fatigue and thermal cracking. While this mini-
mum must be maintained, we prefer to use a somewhat
higher minimum~ and preferably not less than about 0.14%
of vanadium in the alloy. Greater amounts than 0.25%

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of vanadium in the alloy do not produce any improvement
in results and excessive amounts will have a deleterious
effect.
It has been found that in manufacturing the steel
alloy of this inventîon, the alloy elements are placed
in the ladle or added to the molten metal at the begin-
ning of the tap. Silico-manganese, ferro-manganese and
ferro-silicon are preferably placed in the ladle beore
the heat is tapped. When the ladle is partly full, the
vanadium is added, and then aluminum is added as a de-
o~idizer. The vanadium and aluminum are preferably drop-
ped into the stream of molten steel. flowing into the
ladle.
Specific examples are disclosed as follows:
Example Number 1
An electric furnace heat was poured and ~ast lnto
railroad car wheels having the following analysis:
Component Percent-by Wei~h~
Carbon 0.63
Manganese 0.74
Phosphorous 0.021
Sulfur 0.027
~ Silicon o.~o
; Vanadium 0.18
Iron Balance with residual im-
purities in ordinary amounts
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Two samples of cast wheels were normaLi.zed at dif-
ferent temperatures with the fol.lowing results:
Normalizing Yield Strength
Temperature, C ~cg/sq. cm_
Sample A 843 3584
Sample B 982 4507
Example Number 2
An electric furnace heat having the alloy composi~
tion of Example Number 1 but with the carbon content in- ;
creased to 0.73~/0 by weight was poured and cast into
railroad car wheels, and three samples were normalized
at different temperatures, with the following results:
Normalizing Yield Strength
Temperature, C kz/sq. cm
Sample C 843 3826
Sample D 982 4763
Sample E 1121 5347
From the above examples~ it can be seen that the
normalizing of a vanadium steel in the temperature range
of 927C to 1149C produces a superior alloy steel.
Specifically a vanadium steel normalized at 982C to
1121C has been ~ound to produce optimum results.
It should be understood that the arrangement des- -
cribed above constitutes the preferred embodiment and
that many adaptations and modifications may be made
without departing from the spirit o~ the invention.
I