Note: Descriptions are shown in the official language in which they were submitted.
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BACK~ROUND OF THE INVENTION
It is h~ghly deslrable to prepare copper base alloys having
high mechanical strength, excellent stress corro~lon resl~t~nce 'and
~eneral corrosion reslstance especially in severe ammoniacal
environments. It is also desirable to prepare a material of the
foregoing type inexpen~lvely and expedltiously on a co~mercial scale.
The preparat~on Or a material of this type would satls~y the
stringent requirements imposed b~` modern applications ~or electrical
contact springs, for exampleg ln whlch spring temper mechanical proper-
ties are required coupled with adequate bend formability and wlthstress corrosion resistance in se~ere ammoniacal envlronments which
are generated durlng decomposition of organlc electrical insulation
~ materials.
'j Accordingly, it is a principal obJect o~ the present invention
to provide a convenient and inexpensive process for preparing wrought
copper base alloys having improved me~hanical properties.
It is a particular obJect of the present inventlon to pr~v~de a
process aforesaid which obtains ~rought copper base alloys having
' excellènt stress corrosion resistance in severe ammonlacal envlronments
, 20 coupled with high strength and favorable strength to bend ductility
ch,aracteristics.
Further obJects and ad~antages o~ the present invent~on will
appear hereinafter.
SUM~ARY OF THE ~NVENTION
In accordance with thepresent invention it has been found that
the ~oregoing objects may be obtained and improved copper base alloys
provided. The process of the present invention comprises: providing
a copper base all~ containlng ~rom 1.0 to 4.5% sillcon, l'.O to 5.0%
tin, wlth the mlni~um silicon plus tin content belng 3.5%, balance
essentlall~ copper; hot rollin~ said allo~ at a starting temporature
ln exce~s of 650C wlthin 50C of the solldus temperature of the
alloy, and with a ~inishing temperature in exce~s Or 400C; cold
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rolling the alloy at a temperature below 200C and annealing
3aid alloy at a temperature of from 250C to 850C for from 10
seconds to 24 hours. Naturally, ~everal processing variations
are contemplated within the scope of the present invention in
order to obtain particularly preferred properties.
The invention also relates to a copper base alloy
having improved stress corrosion resistance consisting essentially
of from 1~0 to 4.5~/O silicon, from 1.0 to 5.~/O tin, with the
minimum silicon plus tin content being 3~5%, balance copper, ~aid
alloy including a first additive selected from the group consist-
ing of from 0.01 to 2 ~ ~/o iron, from 0.01 to 2, ~/o cobalt, and
mixtures thereof, with a maximum total iron plus cobalt content
of 3~C%~ a ~econd additive selected from the group consisting
of nickel from 0.01 to 5.~/O; manganese from 0.01 to 5.G%;
titanium from 0.01 to 5.~/O~ zirconium from 0~01 to 5~/O; hafnium
from OoOl to S.G%; chromium from 0.01 to 2~/o; beryllium from
0.01 to 3~/o; vanadium from 0.01 to 5.~/O; and magnesium from 0~01
to 2 ~ ~/o and mixtures thereof, wherein the total content of
~aid first and second additives is less than 10.~/o~ and a third
additive selected from the group consisting from 0.01 to 3.~/0
arsenic, from 0.01 to 3.~/O antimony, from O.Ql to 3~o aluminum,
from 0.01 to 3 ~ G% zinc and mixtures thereof, wherein said third
additive is present in a maximum total of less than 5~/O.
It has been found that the foregoing process inexpensively
and conveniently obtained copper base alloys having the highly
desirable propertie~ referred to hereinabover
As indicated hereinabove, the copper base alloy~ pro-
cessed in accordance with the present invention contain from 1.0
to 4.5% silicon and from 1.0 to 5~/O tin. The total silicon plus
tin content should be a minimum of 3,5% in order to obtain adequate
stress corro~ion resistance and other desirable mechanical pro-
perties.
73~7
In accordance with the pre~ent invention it is highly
preferred that the copper base alloys processed herein contain
certain additives in order to provide preferred properties. The
first additive which is preferably included in the foregoing
copper base alloys is from 0.01 to 2.~/o iron, from 0.01 to 2 ~ G%
cobalt and mixture thereof, with a maximum total iron plus
cobalt content being 3.C%, The second additive which is pre-
: ferably included in the foregoing .copper base alloys is selected
from the following group and mixtures thereof: Nickel from 0.01
to 5.0/O; manganese from 0.01 to 5.~/0; titanium from 0.01 to
5.~/O; zirconium from 0.01 to 5.~0; hafnium from 0.01 to 5~0~/O,
chromium from 0.01 to 2~0%; beryllium from 0.01 to 3.0/O; vanadium
from 0~01 to 5.0/O; and magnesium from 0.01 to 2.0/c. The total
content of ~aid fir~t additives plus said second additives should
be less than 10.0%.
i Naturally, the first additive may be pre~ent in the
alloy independently of the second additive, and the second
additive may be present in the alloy independently of the
first additive, so that tha alloy may contain the first
additive without the ~econd additive, or
:
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the second addltive wlthout the ~irst ~ddltive, or pre~erably bo~h
may be presen't toget~er. I~, there~ore~ the second ~ddltlve ls
present ln the alloy and the ~irst additive i8 not present ln the
~lloy, the total content o~ the second additive should be less than
10%.
In accordance wlth the proces's of the present in~ention9 the
silicon and tin c~mponents pro~lde maximum solid solution strengthening
and work hardenin~9 wlth the''sllicon content being crucial ~r
deslred stress corro~lon resistance. The flrst and second ~dditives
referred to hereinabove are pre~erred to obtaln optimum physical
properties. These materials-generally'form dispersed or precipitated
second phases. The morphology of these phases is controlled during
processing to proYide dlspersion strengthening and graln re~inement
and/or preclpitation hardening especia:lly during an aging treatment.
In addition to the foregolng, it is pre~erred to utllize a third
additive selected rrom the following g]?OUp and mixtures thereof, from
0.01 to 3.0% each of the follow~ng materlals and mixtures thereo~:
Arsenlc, antlmon~, aluminum and zinc. The foregolng third additi~es
should be present in a m~ximum total o~ less than 5.0%. The aluminum
additlon is particularly de~irable ln combinatlon with the nickel or
manganese component. Naturall~, the thlrd addltlve may be present in
the alloy independently of the rirst or second additives, or in
combination with elther the rirst or ~econd additives, or preferably
ln comblnation with both the ~irst and second additives.
The alloys processed in accordance with the present lnvention
may be cast by any suitable method. In order to provide a more
homogeneous cast structure and better bar quality, direct chill or
continuous castlng procedures are preferred.
A~ter castlnæ the alloy ls preferably heated at temperatures
between 600C and the ~olidus te~per~ture o~ the partlcular alloy ~or
at least 15 minute~. The alloy is then hot rolled ~rom a startlng
temperature ln excess of 650VC up to withln 50C o~ the solidus
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~emperature o~ the alloy. The hot rolllng ~inishIng temperature
should be ~n excess o~ 4005. The actual sol~dus t.emperature of the
particular alloy will naturally depend on the silicon and t~n contents
; and on the amount and nature o~ any addltl~es. The hot rolllng
reduction is not crltical and wlll depend upon final gage re~uirements.
After hot rollln~ it ls preferred to quench the alloy l~ t~e
alloy compositlon contains ~ny of the flrst, second or third addltlves
in order to maxlmize the amount o~ said additives which re~ain in
solutlon. Thls ls particularly pre~erred wlth respect to the second
additives since they are sub~tantially precipltated out o~ solution
by subsequent processlng ln order to obtain optimum properties.
Subsequent proce~sing includes a heat treatment step in order to
provide a fine disper~ion ~f said second additl~es unl~ormly
preclpitated throughout the matrix of the alloy. This fine dispersion
is significant in obtaining desirable grain slze, mechanical properties
and especially ~tress relaxation. The grain size of the alloys of the
present invention is generally below 0.060 mm., and generally below
0.010 mm. if the alloys contain the first addltlve.
The alloy is then cold rolled at a temperature below 200C, with
or wlthout lntermedlate anneallng. Anneallng may be perror~ed using
strlp or batch proces~lng with holdln~ times o~ from lO seconds to
24 hours at from 250C t~ 850C. The ~lnal condltion o~ the material
may be either temper rolled ~trip or heat treated strip, dependlng
upon desired propertles. Naturally, a plurality of cold rolling and
annealing cycles may be employed.
I~ the alloy o~ the present invention contains the second
addltive re~erred to hereinabove~ the interanne~ling steps 8hould be
strlp anne~ling and should include rapid cooling ~ollowing annealing
so th~t said second addltive may be ret~ned in soluti~n a~ long as
deslred. ~hen the alloy pr~ce~ed herein contains said second
addltl~e, the prGce~sing cycle mu~t lnclude an anneallng atep at a
temperature o~ rrOm 250 to 600C ~or rrom 15 mlnu~es to ~4 hours in
~i4~3~
order to bring said second additive out of solution to provide the
fine, uniform precipitation of said second additive dispersed
throughout the alloy matrix. Therefore, optimum properties are
obtained when the alloy of the present invention is in the wrought
condition and is characterized by a fine, uniform precipitation of
said second additive dispersed throughout the matrix. Naturally~ this
annealing step may be performed in the cold rolling - annealing
sequence9 or as a final heat treatment in the processing cycle. If
the annealing step to precipitate the second additive is performed as
part of the cold rolling - annealing sequence, any subsequent anneals
must be batch type anneals at or below the temperature of the
precipitation) i.e., from 250 to 600C for from 15 minutes to 24 hours
and at no higher a temperature than the precipitation temperature that
is employed. Naturally, the annealing steps prior to the precipitation
annealing step may be as indicated above for from 10 seconds to 24
hours at from 250 to 850C.
The processing cycle should contain a heat treatment step either
as an interanneal or final anneal whether or not the second additive
is present in the particular alloy. This heat treatment step during
the processing Gycle is necessary in order to obtain improvement in
~; the strength to ductility relationship with or without the additives
preferred herein. As indicated hereinabove, this heat treatment step
is at a temperature range of from 250 to 850C for at least 10 seconds.
In accordance with the process of the present invention, the
resultant material may then be formed into any desired part, such as
a spring. One might prefer to perform a heat treatment step on the
formed part in order to provide greater stress relaxation properties.
This heat treatment step should be conducted at a temperature of from
150 to 400C for from 15 minutes to 8 hours.
In the foregoing specification all percentages of ingredients
are weight percentages~
The process of the present invention will be more readily
apparent from a consideration of the following illustrative examples.
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EXAMP~E I
Alloy A o~ the present lnvention, consisting o~ 3% sillcon~ 2.5%
tin, 1.5% iron and the balance copper, was cast from 12~0C into a
steel mold with a water-cooled copper base. The 10 lb. ingot was
soaked at 750~C ~or 2 hour~ and immedlately hot rolled to 0.375~' at a
hot rolllng finishing temperature in exces~ o~ 400C, ~ollowed by cold
rolllng to 0.100" at a temperature below 200C. The alloy was then
annealed ~or 1 hour at 450~C follo~ed by ~urther processing as ~ollows
to provlde metal at 0.020" gage in the as-~uenched and 40, 60 and 80%
cold rolled cond~ion. Some metal was cold rolled dlrectly to 0.020
ga~e, l.e., 80% cold rolled metal. Some metal was cold rolled ta
0.050" gage~ annealed at 450~C for 1 hour and cold rolled to 0.020"
gage, i e., 60% cold rolled ~etal. Some metal was cold rolled t~
0.033" gage, annealed at 450C for 1 hour and cold rolled to 0.020~'
gage~ i.e.9 40% cold rolled metal. Some o~ the 40% cold rolled metal
~a~ annealed at 0.02~" gage at 450C for 1 hour to pro~ide annealed
metal~ i.e., 0~ reduction. The tensile propertles of these condltions
a~e llsted in TabIe I below These properties are compared wlth those
o~ the commercial high~strength copper base alloy~, Alloy B (a
; 20 commerc~al ~lloy de~lgnated as CD~ Alloy 510 ~ having the composition
4.4% tin, 0.07% phosphorus3 and the balance essentially copper~ and
Alloy C (a commercial illoy de~lgnated as CDA Alloy 638 - having the
composikion 2.7~ alumlnumj 1.7% ~ilicon, 0.4% cobalt, balance
essentially copper).
The data in Table I belo~ clearly demonstrates the signiflcant
rolled temper ~trength ~dvantages obtained in accordance wlth the
present inventlon. In addition, the gr~in sizes o~ these alloys were
as rollow~: Alloy A - 0.005 m~.; Alloy B - 0.010 mm.; and Alloy C -
0.005 mm~ Both Alloy A o~ the present lnventlon and commercial Alloy
638 were characterlzed by particulate phases uni~ormly d~strlbuted
throughout the fflatrix. The partlculate phase ln the all~y o~ ~he
pre~ent in~ention was a mix~ure of alpha iron and lron sillcide.
~1969~737
TABLE I
TENSILE PROPERTIES
Ultimate
0.2% Yield Tensile
% Cold Strength Strength Elongation
Alloy Reduction (ksi) tksi) . (%) _
A 0 65 84 23
B 0 40 56 46
C 0 5I 80 35
A 40 109 130 ~ 0
B 40 93 97 5 0
C 40 99 120 5.0
: 10 A . 60 125 142 1.2
B 60 107 110 2 0
: C 60 110 130 3 0
~: A 80 130 148 1.0
B 80 114 120 1.0
C . 80 116 136 2.8
EXAMPLE II
Alloys A and C, processed as in Example I, in the 0%
cold rolled, 40% cold rolled, 60% cold rolled and 80% cold
rolled conditions, were subjected to stabilization (stress relief)
anneals at about 320C for 1 hour. The 90 bend properties for
these stabillzed materlals were then measured. The re~ulting data
presented in ~able II below were based on plots of 0.2% offset
yield~-strength versus the ratio of bend radius to thickness (R/t)
so that the bend properties could be easily compared at.an equi-
valent 0.2% yield strength. For comparison purposes the bend
data was determined ~rom published data ~or Alloy B and ~DA
Alloy 688 (Alloy D - having the.composition 22.7% zinc, 3.5%
aluminum, 0.38% cobalt, balance essentially copper) and is
: included in Table II.
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The bend properties determine the minimum radius about
which strip could be bent without cracking either parallel to
or perpendicular to the rolling direction. The longitudinal
properties refer to the axis perpendicular to the rolling
direction (goodway) and the transverse properties refer to the
axis parallel to the rolling direction (badway). R is the
smallest radius which does not crack and t is the thickness of
the strip, i.e., all at 0.020" gage~ It is significant that the
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'73~
present invent~on o~ers bett.er goodway bend properties than
commercial CVA Allo~ 638 ~nd ~88 and.bet:t:er bad~ay. bend properties
than commerclal CD~ Alloys 510 and 638. It is partl.cularly si~nificant
that the alloy o~ the present lnven.tion has adequate ductillty at
strength le~el~ the.other alloys cannot obtain.
TABL~ II
BEND P~OP~R~IE~
: Alloy 0.2% Yield
StrengthIangitud~ Tran3verse
- (k~i~- -- R~t ~ t _
A 80 0.3 1.1
B 89 0.3 1.5
: ~ 80 -0.7 2.0
. D 80 0.8 0,9
A 100 1.3 3.8
B 100 1.0 5.2.
C 100 1.9 5.2
D 100 2.2 2.1
A 110 2.2 6.6
B 110 1.8 9.0
I C liO 2.3 10.0
:: D 110 2.~ 3.3
A 120 2.2 14
EXAMPLE IIX
~ Copper base alloY~ of t~e present lnvention cont~inlng silicon,
tln and lron ~ere chill cast as 10 lb. ingots ~s in ~x~mple I. They
were processed~as in Example I and annealed to provide metal at
0.0307' gage ln the 50% cold rolled temper as ~ollows: hot roll ~rom
750~C to 0.375" gage with a rlni~hin~ te~perature ~boYe 400~C; cQld
roll below 200:C t~ 0.120". gage; anneal ~t 450C ior 1 hour, cold roll
to 0.060~ gage b~low 200C, anneal at 450C for 1 hour; and cold roll
50% to 0.030~ ga~e ~t bel~w 200.C. The alloys were stress corroslon
tested in moi~t amm~la in the ~oll~ing manner. The amount o~
springback ~ter ~e~Q~ m a te~t Ji~ wa~ measured ~ersu~ exposure
time wlth U-bend sh~ped ~pecimen~ In thi~ te~t the stre~s corro~ion
parameter o~ mo~t .~nte~est i~ th~ ti~e ~r 80% ~p~lngback. The hlgher
the v~lue ~ thi~ pa~eter, the mQre re~l~tant the all~y to stress
corro~ion in the particular environment. The gtre~s corrosion data
~4737 5022_MB
and the trans~erse tensile pr~perties are shown in Table III below.
For comparison~ si~ilar data are shown ~or commercial CDA Alloy 510
tAlloy B) and com~ercial CDA Allo~ 638 (Alloy C). These data clearly
show the excellent stress corroslon reslstance obtained ln accordance
with the present lnvention. It can be clearly seen that tln alone, as
in commercial CDA Alloy 510, does not provide the desired resistance
to stress corrosion. Furthermore, silicon in comblnation wlth another
element such as alu~inu~, does not yleld the excellent reslstance to
stress corroslon as does the present lnvention. Therefore, lt ls most
surprlsing that the silicon and tin combinatlon ln accordance with the
present invention pro~ides such exceIlent stress corrosion resistance.
.
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69~737
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~ .737 5022_MB
~ EXAMPLE_IV
In this example addltlonal d~ta w~s obtained sh~wing propertles
or a variety of materials. Allo~s A, B, C, and D are as indlc~ted
hereinabo~e. Alloys E, F, G, H, and I have the composition set forth
in Table IV-A below. Alloys A and E through I were processed in a
manner after Examples I and II as set out below: hot roll from 750C
to 0.375" ga~e with a ~inishing temperatu~e above 400C, cold roll
to 0.120t' gage at below 200.C; anneal ~t 450C ~or 1 hour; cold roll
67~ to 0.040" gage ~t belo~ 200~; anneal at 450C for 1 hour; and
cold roll 50% to 0.02~" gage at below 200C. The resultant tensile
and bend properties are shown in Table IV-B and Table I~-C below.
For comparlson purposes similar data is shown for Alloys B, C and D.
~BLE IV-A - COMPOSITION
AlloySilicon % Tln % Cobalt % Iron %
E 3.0 2.5 1~5
F 1.5 4
G 2.0 4 - -
H 2.. 0. 3.5
. I 2.. 0 3.5 - 1.5
T BLE_IV-B - TENSILE PROPERTIES
Ultimate
. 0,2% ~leld Tensile
% Cold Strength Strength Elongation
Allo~ Reduction (ksi) (ksi) (%)
A 50 120 137 1.5
B 50 101 103 3.0
C 50 105 126 4,o
D 50 116 128 2.0
E 50 120 137 1.5
30 F 50 . 106 114 6.6
G 50 110 123 2.5
. -.H . 50. 107 120 2.0
I 50 120 133 2.5
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TABLE IV-C - BEND PROPERTIES
P..~%. ~ield
Strength Longltudinal Transverse
Alloy (K5i) R~t R~t. _
A 100 1.3 3.8
B 100 1.0 5.2
C 100 1.9 ` 5.2
: D 100 2.2 2.1
E 100 1.2 .~ 4.6
~ 10 F 100 1.2 ~ 5.0
: G 100. 1.6 4.7
H 100 0.8 3.8
I 100. 1.2 3.0
The foregolng data clearly ~hows that the alloys o~ the present
inventlon have hi~her yield strength than Alloys B and C for equivalent
cold reduction. Specirically referring to Table IV-C, the bend data
shows that the alloys of the present lnvention have better
longitudlnal (goodway) bend properties at comparable yield strength
than the comparatlve alloys excluding Alloy B, and have better
transverse (badwa~) bend properties than the comparative alloys
excludlng Alloy D.
This invention may be em~odied in other ~orms or carrled out in
~: other ways without departin~ from the spirit or essential
characteristics thereor. The pre ent embodiment is therefore to be
considered as in all respects illustrative and not restrictive, the
scope o~ the invention bein~ ~ndicated by the appended claims, and
all changes which co~e'wlthin the meanin~ and range o~ equivalency
are intended to be embraced therein.
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