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Патент USA US3047391

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United Sttes
3,047,382
Patented July 31, 1962
' 2
1
Cobalt base alloys of the foregoing composition may
be made according to normal procedure for high strength
3,047,382
AGE HARDENING COBALT BASE ALLOY
Norman R. Harpster, Canonsburg, Pa., assignor to Uni
versal-Cyclops Steel Corporation, Bridgeville, Pa., a
corporation of Pennsylvania
No Drawing. Filed Jan. 13, 1959, Ser. No. 786,463
8 Claims. (Cl. 75-171)
alloys. For example, the alloys may be air or vacuum
melted, or melted in a controlled atmosphere, and cast '
into ingots. These ingots may be wrought by usual mill
practices into forgings, bars, sheet, strips, or other forms.
The resulting products may then be used for producing
This invention relates to cobalt base alloys that com
various useful articles that are now prepared from high
strength cobalt alloys. Either the bar or ?nished article
10 may be solution heat treated and aged to the desired de
and having good stress-rupture strength.
gree of hardness.
There are commercially available cobalt base alloys
The excellent properties of the alloys of my invention
that evidence strength maintained at high temperature.
and the high degree of response to heat treatment in ad
Conventionally such alloys ‘are strengthened by the addi
dition to the characteristically good tensile properties and
tions of elements such, for example, as tungsten, molyb
good stress-rupture strength are exempli?ed by alloys
denum and columbium. To render such alloys respon
prepared with a melting aim, by weight, of 0.25 to 0.30
sive to heat treatment so that the best characteristics of ' percent of carbon, 20 percent of chromium, 20 percent of
bine the desirable characteristics of being age hardenable
by heat treatment to high hardness and tensile properties
strength, tensile properties and hardness are obtained, al
loying additions of titanium and aluminum have been
used.
It is therefore apparent that the desirable properties in
nickel, varying percentages of phosphorus and the balance
cobalt. Four heats were prepared so that they would have
20 the same basic composition ‘except for a variation in the
such cobalt base alloys are achieved in a way that is of
considerable signi?cance from an economic point of view.
The base alloy itself is costly and the addition of expen
sive alloying constituents further increases the expense 25
involved.
It is an object of the present invention to provide new
and useful cobalt base alloys that can be age hardened
by heat treatment to high hardness and tensile properties,
and have good stress-rupture strength.
It is another object of this invention to provide alloys
in accordance with the foregoing object without need to
use highly expensive alloying additions.
The invention is predicated upon my discovery that its
phosphorus content; _ The analyses of the four heats were
as follows:
Table 1
Heat
0
P
Or
Ni
Co
0 25
0 21
0. 30
0.003
0. 081
0.100
19. 54
19. 54
19. 72
18.90 Balance.
18.90
Do.
19. 40
Do.
0. 31
0. 240
19. 72
19. 40
Do.
stated objects are attained with cobalt base alloys con 35
taining, by weight, at least 0.10 percent of carbon and
the remainder cobalt to which is added at least an amount.
All four ingots were forged into bars from which speci
of phosphorus that is effective to characterize the result
ing products with age hardenability.
mens were obtained to determine the response to aging,
A composition
stress-rupture characteristics and tensile properties at
range ‘for alloys of my invention within the foregoing 40 room and elevated temperatures.
broad range is, by weight, 12 to 30 percent of chromium,
The aging data on these four heats, shown in Table III,
10 to 30 percent of nickel, at least 0.10 percent of carbon,
Where obtained at aging temperatures ranging vfrom 1100°
up to 20 percent of iron, at least 0.08 percent of phos
to 1600° F. after solution treating at temperatures from
phorus and the remainder cobalt. In addition, incidental
1900° to 2200° F. and water quenching. These data
impurities and alloying elements that do not deleteriously 45 were developed on standardized tests with respect to time
a?ect the ‘desired characteristics ‘of the resulting alloy
‘at both solution and aging temperatures. In addition'to
may be present. For example, additions of molybdenum,
the data on heats A, B, C and D, data on four other heats
tungsten or both may be made in amounts of about 0.5
are included in Table III. The analysis of each addi
to 5' percent where it is desirable to further enhance ele
tional heat was:
vated temperature strength and the cost of such additions 50
is not prohibitive, considering the desired result.
Within the foregoing limits, I now prefer that the phos
phorus-containing cobalt base alloys of my invention con
tain, by weight, about 0.15 to 1.00 percent of carbon,
0.08 to 0.40 percent of phosphorus, 12 to 30 percent of
chromium, 10 to 30 percent of nickel, 0 to 20 percent of
iron and the remainder cobalt along with incidental im
purities and alloying elements as above described,v if de
sired.
'
Table II
5
Heat
0
P
Or
Ni
Mo
E ____ __
F ____ ....
0.40
0. 43
0.28
0. 37
10.20
19. 2O
18.92
18. 92
1} ____ __
0. 33
0.20
19.30
19.04
2.27
H ____ -_
0.39
0.25
19.30
19.04
4.48
'
w
______________ -_
______________ __
2.24
______ -_
c0
130101100.
D0.
Do.
D0.
A typical composition range within which the maxi 60
mum bene?ts of my invention would be attained is 0.15
to 0.75 percent of carbon, 0.15 to 0.40 percent of phos
phorus, 12 to 25 percent of chromium, 10 to 25 percent
of nickel, 0 to 15 percent of iron and the remainder cobalt
along with incidental impurities and alloying elements as 65 The hardness data together with the heat treatment used
on all of the foregoing heats were as follows:
previously described, when desired.
‘
3,047,382
5
of phosphorus and the remainder cobalt together with
6
about 0.5 to 5 percent of at least one element selected
from the group consisting of molybdenum and tungsten.
incidental impurities and elements that do not deleteri
8. An age-hardenable cobalt base alloy consisting es
ously affect the characteristics of the resulting alloy.
sentially, by weight, of 0.15 to 0.75 percent of carbon,
3. A cobalt base alloy in accordance with claim 2,
0.15 to 0.40 percent of phosphorus, 12 to 25 percent of
said carbon content being in the range of 0.15 to 1.00 5 chromium, 10 to 25 percent of nickel and the remainder
percent.
cobalt together with incidental impurities and elements
'4. An alloy in accordance with claim 3 ‘containing
that do not deleteriously a?ect the desired characteristics
about 0.5 to 5 percent of at least one element selected
of the resulting allov.
'
from the group consisting of molybdenum and tungsten.
5. An age hardenable cobalt base alloy consisting es
References Cited in the ?le of this patent
sentially of, by weight, 0.15 to 0.75 percent of carbon,
0.15 to 0.40 percent of phosphorus, 12 to 25 percent of
UNITED STATES PATENTS
chromium, 10 to 25 percent of nickel, up to 15 percent
2,200,742
Hardy ______________ __ May 14, 1940
of iron and the remainder cobalt together with incidental
2,513,303
Feild __________ _‘_ ____ __ July 4, 1950
15
impurities and elements that do not deleteriously ‘affect
2,643,221
Brenner et al _________ __ June 23, 1953
the desired characteristics of the resulting alloy.
6. An age-hardenable cobalt base alloy consisting es
OTHER REFERENCES
sentially, by weight, of 0.15 to 1.00 percent of carbon,
“Haynes Alloys,” 1950, pages 26, 27, 32, 33, 84 and
0.08 to 0.40 percent of phosphorus, 12 to 301 percent of 20 85. Published by Union Carbide Corp, New York, NY.
chromium, 10 to 30 percent of nickel ‘and the remainder
Hansen: Constitution of Binary Alloys, 1958, pages
cobalt together with incidental impurities and elements
488-489.
Published by McGraw-Hill Book 00., Inc.,
that do not deleteriously affect the desired characteristics
New York, NY.
of the resulting alloy.
7. An alloy in accordance with claim 6 containing
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