CA 02561903 2006-10-02
Mathittable copperJbased alloy and production method
Technical field
The present invention concerns are alloy based on copper, nickel,
'tin, lead anc9 its production method. !n partic~.llar, tho~.lgh not
exclusively,
S the preserot iroverttion concerns am alloy based on copper, nicl<ol, tin,
lend
easily m~lchiroed by ttlrroirlg, slicing or milling.
State of the art
Alloys based on copper, nickel end tin <3re Known arld widely
used. -they offer excellerlt mechanical properties and exhifJit a strolig
t~Zrderair~g during strain-hardening. Their mechanical properties arc'
fl.lrther
improved by the known feat-acing treatment such as spinodal
decormposition. For ~n alloy containing, by weigklt, 15% of nickel arld F3%
of tire (standard alloy ASTM C7?.9(~p), the mechar~ic~ll resistance earl reach
1 S00 MPa.
1!p Another favorable property o'f the Cul-Ni-5 alloys is that they
offer good trik~ofogical properties, comEoarable to those o-f bronzes, while'
exhibiting st~pc~rior mechanical properties.
Another advantage of these materials is Choir oxcellernt
fiorrllability, combirled with 'favorable elastic properties. Moreover, these.
~~I~Uys Uffer cl goOd rE.'sl5'~clrlCC'. dgdirl5'l COrrO5lorl and arl
C'XCC'lIC'nt rC'Slst~'3r'1CC'
to the constraints' heat relaxa'tior~. f=or this reason, the ~r.r-Ni-Sn
springs do
not lose their compression force with age, even rlrlder vibrations and strong
boat strossos.
Theac~ favorable properties, col~nbir~ed with good heat and
~5 electricity Cor~ldllctlvlty, moan that these materials tare widely rlsed
'for
making highly reliablo connectors for telecomrnunicatiorls and 'the car
indrlstry. These alloys are also ~.lsed in several switches or~d electrical or
s Nl r-. r nl.. > m: ~-
CA 02561903 2006-10-02
Z
electromechanical devices or as supports of electronic components or for
making bearing friction surfaces srabjected to high charges.
The Cr.u-Be alloys can be machined fairly weft and can contend
with and were outperform the mechanical properties of Cr.l-Ni-Sn alloys.
The' machinability index of the Cu-Be alloys car-~ reach 50-~0% relatively to
standard ASTM C3G000 brass. Their cost is however' high and their
productiorn, rrse and recycling are particularly constraining because of the
ber'yllirrm's higl7 toxicity. The resistance to the constraints' heat
relaxation
of 'these materials is lower ~cl-~an tf~oat o~t~'the Cu-Ni-Sri for
ternperat~.rres
1(7 above 150-1'75°~:.
One' inconvenience of the Cru-Ni-Sn alloys is however that they
are poorly sr.lited to processes si-rch as milling, tr_~rr~iry or sliciroc~ ar
is ar~y
other known process. A further ir~cor~veroiertce of these n3loys is Cheir
strong
segiegwlior~ during cosUirog.
15 It is thus an aim of the present invention to propose ar-~ alloy
associating the favorable mechanical characteiistics of alloys based on
copper, nickel and tin with a good workability.
It is ~rnother aim of the present inver~liol~ to propose a method
for prodecir~g a rnachinable product on the basis of Crn~Ni~sl~ free from the'
20 incorwer~icnccs of the prior art.
ft is another airt~ of 'the present irmeotion to propose a
machiuable alloy combir~ir~g high elasticity arid rnechar~icnl resistance
characteristics brlt free 'from berylli~rrn or 'toxic eiernervts.
A IVrr~ther airn of the present irvver~tior~ is to propose a r~nc~tl~ocf for
25 producir~d a rnachirnable product on the basis of Crl-Ni-Sn allowing the
problems relative to se c3regation to be solved.
~l-hese aims are ~~chieved by the product and thc~ method that arc'
the object of the independent claims of corresponding category and
5Mf-_-1-AI_-2_r'C:1
CA 02561903 2006-10-02
3
notably by a machinable product composed of an alloy camprisir~g between
1 % arid 20% by weigl'~t of Ni, between 1 % ancf 7_0% by weight of Sn,
betweero 0.1 % arid 4% of Pb, the remainder being constituted essentially
of Cu, having ur'~dergorve a heat homogenizing treatment comprising a step
o'f~ heatirng said alloy followed by a step of cooling at a speed sufficiently
slaw to prevent 'fissuring.
pet~_i_Ied..descripvtior~ ofythe inveroior~
the present irwention concerns alloys oro the basis of copper,
nickel, tin and lead Obtc~rneC:l by c~ cOntrnL.roUS Or S2lTll-CUrltlr'tUUUS
C~35'tIr7C)
method, a static billet casting or casting by spr~yforming. -fhe copper-
nickel-tin alloys have a long solidification interval leading to a
considerable
segregation durirog c~s'ting. Uf the 'fo~.~r aforementioned processes, casting
by sprzyformir~g, also known by the name "Osprey" method, ar-id described
far exarnple ire patent FPO?_?_573? makes it a possible 20 ob'lain an almost
W homoger~or~s microstructrare presc~ntinc~ 7 f1'tlnlr'1'lr'71 degree of
segrecla'tlon.
In 'this process, a metal billet is obtained by contirmrarrs depositing of
artdmized droplets. "I'E~Ze segredatioo carp take place only on the scale' of
the
ator~iz~d droplets. The clif'fusior~ distarvces reqceired 'for dir~~inishing
the
segregation are th~.ls shortened. Irn the Case wl' corotine.roces or semi-
7_0 cor-~tinuot-rs casting, the segregation is stronger than with 'the
sprayforming
process, br-et it remair-~s sr-efficiently reduced to void an excessive
fragility of
tEte alloy. ~~fhe static billet casting leads to a strong segrc~c~ation that
can be
elimir~a~ted only by a prolorycd heat processing.
Lead being essen'tiolly insol~rble in 'the other metals of the alloy,
75 the prodLlct obt~in~d will comprise lead particles dispersed in a Cry-Ni--
sn
matrix. Drjring the machining operations, floe lead has a It.rbricating effect
and facilitates the fragrz~er~tation of the slivers.
The quantity of fend introd~.rced in the alloy depernds ora 'the
degree of rnachrnabllity that one streves to achieve. Geroerally, a
qr.ranti'ty of
3o lead up to several percents by weight can be introduced Wlt~lUUt the
alloy's
mechanical properties at normal tc~mpc~ratr-ere being modified. lwlowever,
an~r: one.-z-her
CA 02561903 2006-10-02
4
above 'the lead melting point (327 °C), the liquid lead strongly
weakens the
alloy. Alloys containing lead are thus difficult to make, on the one hand
because they have a very strongly pronounced tendency towards fissuring
and, Ur'1 the other hand, because they can exhibit a two-phased
crystallographic strrscture containing are undesirable weakening phase.
°fhe method of the present invention makes it possible to
produce a rr~achirzabfe Cu-Ni-Sr~~Pb prodr.lct contairrir2g up to several
percents by weigh~l of lead, without it fissuring during fabrication, and
having excellent mechanical properties, The ratio of lead cc~n vary between
0.1 % and 4% by weight, preferably between 0,7.% and .3% by weigf7~t, even
more preferably between 0.5% and 1.5% by weight.
After smelting in the foundry, the production methods can be
decomposed In slrCCe55ive Sll-lgs: far the first slug, two cases must be
considered according to whether the product is manufactured by
contir,uor.~s casting at small dianoeter or by static billet casting,
sprayforming, semi~continirous or contirmoras casting at large dir~me-cer.
'T'he pr-odt.rcts of the invention are characterized by their excc~llc~nt
rnachinability, wf'~ich is c3reater than that of Cr.r-Be .~Iloys. The
machirrability
index of the inventive alloys exceeds X30% relatively to standard AS~rM
?0 C36000 brass and can even reach ~~0%.
First-sl~.y-g:
Alloys obtained by contim.rous sm~3lf-diameter thread casting, c.g.
of 25mm or less, urodergo a heat homogenizing irea~er7ren~l or a step of cold
deformration by harnrneriry followed by a horr,oger~izir~g t~r,d
75 recrystailization treatment. 'fire temperatr.rre of the heat tremurnere
mast be
within the range where the alloy is arse-phased. Cooling after ll7e heat
treatment must occur at a speed sirfficier~tly slow to prevent fissnriry of
tire
alloy drre to internal cor~s~trair~~ts generated by the temperature
differences
d~.iring cooling, and st~f-licier~~lly fast -to limit the: formation of r~ two-
phased
30 strncturc~. If the speed is too slow, a considerable yrantity of secorod
phase
s nn r_ rm--z-ro:: r
CA 02561903 2006-10-02
a
carp appear. ~hhis second phase is very fragile and greatly reduces the
alloy's
deformability. The critical cooling speed reqraired to avoid the formation of
too large a quantity of second phase will depend on the alloy's chemistry
and is grea'ter'for a higher quantity of nic!<c~l and tin.
Moreover, during cooling, transitory internal constraints r'~re
generated within the alloy. They are linked to t~mperat~.ire differences
between the surface and the center of the product. If these constraints
exceed the alloy's resistance, the la'c'ier will 'fiss~~re arid is roo longer
~.rsable.
Ir7terrval constraints dr.re to cooling are all 'the higher the more the
prodract's
diameter is large. The critical cooling speeds to avoid fissuring thus depend
on 'the product's diameter. This problem is even more acute wi't~5 Cu-Ni-5n-
Pb alloys since above its ~rreltiog temperature of 327°C, lead
strongly
w~al<ens the alloy.
In the method of the present irvverotior~, cooling after heat
treatment occc.rrs at a predetermined speed -taking into acco~~r~'t the
alloy's
chemistry and the transversal dimerosior-~, or diameter, of the produc't. -1-
he
cooling speed must be at the same tirrre sr.rfficiently slow to prevent
fiss~~ring and sufficiently great to prevent too large a qr.rantity of
fragilizir~g
phase to form.
Unrir~g rnanufacturc~ of a large-diameter prodt.ict, 'the in'ter'nal
corostrariro'ts due to 'floe temperature differences are greater Chars irv a
small-
dimensioro product, or~d the cooling speed mast conseqr.rently be limited. At
the same tune, strong propor'tior~s of Ni arid Sn promote the formation of a
fragilizing phase and require a fv3ster cooling.
z5 Alloys ohtained by sprayforrnirog, static billet casting or sc~mi~~
corotimaor-rs casting undergo a hot extrusio~o 'lreatmerot. ~f-his is also the
caso
for con'tir~e-roras casting if the product is of I~~rge diameter. Cooling
during
extrusion rz~ust be svafficiently slow to prevent fissurirog and
srnf'Ficier~tly fast
to limit the formation of a fragilizing secorrci phase. Alterroalively, if
cooling
during extrr.rsion is too slow, heat homogenizing arnd recrys'tallizatior~
snn r-rm--z-r~~_ r
CA 02561903 2006-10-02
treatments as explained l7ere above for the case of small-diameter
continuous-casting products mt.~st follow extrusion.
Once the 'first sfe~g has been made, 'the final rnachinable product
must be either ob'tair~ed directly by one or several cold deformation
operations, e.g. by rolling, wire-drawing, stretch-forming or- any other cold
deformation process, or obeairoed by one or several successive slt.rgs.
5ycc.~SSiveslugs:
from the first slug, the followiry slugs are obtained by oroe or
several cold deformation operations followed by a heat recrystaliiz~tion
30 treatmervt. '1"he temperature of the recrystallization treatment must be
within the range where 'the alloy is one-phased. Coolirng after the heat
treatment mtast have a speed st~'f'ficier~tly slow to prevent fissuring but
always sufficierotly fast. to limit 'the 'forrna'lior~ of a two-phased
s'lrurtt_tre.
'l~~hrot.rgh successive slr.rgs, thC'_ slZe Of the product is redrmed. From
the las~c
slug, the fiir~ol product is obtained by one or several cold deforr~~atior~
opc~ratior~s.
The mech<3nical properties of the alloy oi.~tain~c~ corn be
snbseqetewtly increased by a spinad~~l decomposition heat treatr'aoerot. -1-
iois
trezornewt cao 'take place before the final machining or after the latter.
70 f-ierewfter, examples of rz~ethods ~~nd of rn7chinable prodt.rcts
according to the preserot ir~ver7~tior~ will be presented. Ira the following
examples, the cooling ternperotures refer to thc~ enter of the prodt.rct.
F. x ~-rz~_p 1-c---1-
The chemical corrrposition of tt~e alloy in this c~xamp(e is given by
table 1:
snnrr nl -z-hc:-r
CA 02561903 2006-10-02
7
c~~~e 1
CompUrlerlt ~rbpOrtibrv. (by WeLC~ht~
Cll ren'lalnder
Ni 7.5%
5n 5%
Pb 1
Mn 0.1%-1%
other <_0.5%
Manganese is introduced in the composition as deoxidizer, It is
however possible to use ir~ste~d other eiemerr'ts or deVICes preventing the
alloy from oxidizing.
This ailoy carp be cast according to the different methods
merotior~ed furtk7er above. Irr this example, this alloy is obtained by
contirvitous billet cas'tirng with a diameter of lFiUmm.
F_i_rst__sly,lg: the' billets are extri.aded for example to o diameter of
l 8mrz~. At the exit of the extrctsior~ die, the' alloy is cooled by ~
strea~'n o'f
compressed air allowing a cooling speed of 50°C/rnir~ to
300°Clmin to be
achieved, as rneasr.rred a't the cer~'ler of 'the alloy. This speed is
sufficic~ntfy
slow to avoid fissuring and sufficiently fast to limi't'the 'formation of a
fragilizing S(?COrld pklc7se, cooling by water spray ccm also be r.rsed,
possibly
allowing cooling sp~c~ds of .300°Clmin to 1000°Clmin to be
achieved without
fissuring of the material. Other means for reaching a suitable cooling speed
car? also be l.~sed. If cooling at the exit of the extrrrsior~ die' is not
sr~fficiet~tly
fast, a too great a proportion of second pi~ase care form, tf~e alloy will
have
'to ttrldergo o horr~oc~er~ization treatrnerl'l with 'the sarme
characteristics for
the cooling speed at a tempera'tr_rre wi'tl'~in the rar~de where the alloy is
2U one-phased, i.e. betweero 690°C anc3 92()'C for tk7e cornpositiorn
of table 1.
S_c~co»c~ slug: the material of the first slag of a diameter ofi 1 t3mm
is rolle;~d to a diamc~t~r of 13mm thin ar~n~aled ire a through-'type
fe.rrnace or
removable cover f~.irnacc. For the alloy with the chemical cornpositioro ofi
exar7iple 1, the annealing temper~~trirc~ must be comprised betweero 59U~C
7.5 and 9?0°C. A cooling spc~c~d on the order of 10°Clmin is
sufficient to limit
the formation of second phase' for this compasitior~ and this diameter of
s ran:w n n-z-sm-
CA 02561903 2006-10-02
8
l3mm, Furthermore, water spray cooling at speed of 300°Clmin tQ
3000°C/mir~ allows fissuring to be prevented and the formation of a
fragilizing secorod phase to be limited.
Fi-r~is_h_ir~~: the rrraterial of tile second slag is wire-drawr-~ or
stretch-formed to a diameter of 8mm to obtain a machir~able product. A
spinodal decomposition ~CreaOrner~~l is finally perforrmed on the machinable
produce or orr the rnachiroed pieces to obtairo optimal mechanical
propertres.
F_x,~ m_EOl ~..
The chemical composition of the alloy ire this example is given by
table Z:
Table z
Component Proportion (by weight)
Cu rernairrder In this exacmple, this
Ni 9% alloy is obtained by continuous
5n 0% 15 thread castirog with a di~rz~eter of
Pb 1
Mrl 0,1 %-1 % 18mrZ~.
Imp~iri~ties <0.5%
I-irs 5~~ag: the thread
~.mdergoes a homogenization treatrnent in a tf~rough-type fv_irn~ce at a
temperotrire between 700°C and 970°C, corresponding to the
one~phase
,~0 mange of thc~ chemical composition of exarT~ple 7. A cooling speed between
100°Clrnin and 1000°Clr~~rir~ allows fissuring to be prevented
arod the
proportion of fragilizir~g second phase to be limited. Such cooling speeds
can for- exarrrple be achieved by usiry compressed air, water spray or a
gaslwater excharngirog cooler.
25 Ser_o~yc~ slug: the rnateriol of the first slug of a diarr~e~ter of lF3mm
is rolled, wire-drawn or stretch-'formed co a diameter of l3r~nm then
oranealed in za through-type furnace at a temperature conoprised between
700°C and 920°C. WiOir a diameter o~F l3mrn and the chemical
composition
snntrm...o.io.:r
CA 02561903 2006-10-02
c3
of table ~, a cooling speed betweero 100°Clrnin to 3000°Clrnin
allows the
formation of a second phase to be limited while avoiding fissuring.
Third-s!_rrg: the material of 'the second slug at a diameter of l3rnm
is rolled, wire-drawn or stretch-formed to a diameter of 10mm then
a annealed in a throragh-type 'furnace or tempering furnace at a temperature
comprised betweero 700°C anc9 920°C. With a diameter of 10mm and
the
chemical composiliora ov table 2, a cooling sped betweew100°Clmin to
15000°Umin allows the formation of a second phase to be limited
withor.rt
any fissurirog being created.
1() Fo~.irth-sl-a.yg: the material of the tl7ird slug a~t a diameter of l0mm
is rolled, wire-drawn or stretch-formed 'to a dizo~neter of 7mm then
annealed ire a through-'type 'furnace or tempering furr~.-~ce at a
temperatrare
comprised betweerv '700"C arod 920"C. With a diameter of 7mm and the
Chemic7l Cor'npositiorl of table 2, a cooling speed between
100°C/min to
15 20000"Clmin allows the forrz~atior~ of a fragiiizing SecUrld phase to be
limited withor.rt any fissr.rrir~g being created.
f:yivftf~ slug: the material of the fourth slug at a diarzieter of 7a~m is
rollecJ, wire-drawn or stretch-formed to a diameter of 5mrz~ then ar~r~ealed
irr a tfirorrgh~type f«rnac~ or t~mpcrirlg furnace at a ternperatnre
20 comprised b.ntwc~c~n 700"C armJ 9z0"C. lNitl~ a diameter of 5rnrn arnd ~lhe
chervical composition of table z, a coalir~d speed between 100°Clmirr
to
30000"C/r~~ir~ allows the for matioro of a fragilizing second phase to be
limited withornt ar~y fi5surir~g being created. A cooling speed on the order
of 15000°Clrniro can be acP~ieved by tempering in appropriate fluids.
25 Sixtp_sliig: the material of the fifth sl~.rg at a diarz~eter of 5mm is
rolled, wire-drawn or stretch-formed to a diameter of 3mm, ar~r~ealed in a
through-type furnace or tempering fr.rrnace at a temperat~.rre comprised
betweern 700"C arid 92_0°C, then cooled at a cooling speed comprised
belweer~ 100°Clrnin to 40000"C/rr~in.
sMr_nnc_-z-ro: r
CA 02561903 2006-10-02
SeverytPy.sl_r.i.~: the material of the sixth slag aU a diameter of 3mm
is rolled, wire-drawn or stretch-formed to a diameter o~f zmm, annealed ire
a through-type furnace or tempering furnace at a ternperatr.rre comprised
between 700°C and 920°C, then cooled at a cooling sped comprised
5 between 100°Clmin to 40000"Clmin.
Eigtyth slug: Ohe material of the seventh slug at ~3 diameter of
7mm is rolled, wire-drawn or stretch-formed to a diameter of 1,60mm,
annealed in a through-type ~furr~ace or tempering furnace at a temperature
com~~rised between 700°C and 920°C, and then cooled at a cooling
speed
1U cornprised between 100°C/min to 500UU°Clr~nin.
f~irpishing: 'the material of the eighth slug is rolled, wire-drawn or
strotch~formed to a diameter of lrnm to obtain a m~ichinable product. A
spinodal decomposition treatrnewt is finally performed on the m7chiroable
product or on the machined pieces to obtain optimal rrrec.hanic~~l
properties.
1 he "AS I M 'lest method for rnachin<~bility" test proposes a
method for determiroirag ~cF~e rnachinability index relatively to standard
Cu7r~39f~b3, or c:3f~000 brass. "fhe machinability index of the alloy
according
tc~ this aspect of the invention is better by F30%.
LxampLe 3
The chemical CUrllpOSltlOrl Of thc~ alloy ire this example is the sar~c~
as that of the secorvd example given by table 2_. In this example, the alloy
is
obtained by COiltlr~lllOUS C~~Stll'1C~ at a diameter of ?..5mm.
Fi_rst___sf_r,ag: the thread cast at a diameter of ?5mrrr is hammered to
z5 a diameter of 1Umm. The hammering allows the material to deform with a
considerabie redaction rate without prior heat homogenizing treatment.
Wi~lh tlois method, a high remainder ratio of fragilizing second phase can
be Oolerated at this stage. The second phase carp reach a volume ratio orr
the orc9er of 50%_
snnc rnr, z-nc:r
CA 02561903 2006-10-02
After hammering, the thread at a diameter of l6mm undergoes
homogenizing and recrystallization treatment in a thrm.rgh~~typc~ furnace.
The terr~perature of the heat treatment must be comprised between
7p0°C
and 9~0°C. The following cooling will take place at a speed comprised
beUween 100°C/min and 300o°C/r7~ir~. These cooling speeds make
it possible
to prevent ~fissrtrir7g ar7d to limit the ratio of second phase for a product
of
this diameter arid of this corn position. 5tich speeds carp be obtained by
using compressed air, w~rler spray or gaslwater exchangers.
F-in_ist~ing: the materizol of the first slug is wire-drawn or stretch-
formed to a diameter of 1Ornm to ok~tain a machinabfe product. A spinodal
deCOmpositiorl treatment is finally performed on the machinzble product
or oro the machined pieces to obtairo optimal mechanical properties.
Exymple 4
The chemical composition of the alloy in this example is givero by
table 3:
Table 3
Component Proportion (by weight)
Ct.i remainder
Ni 15%
Sri B%
f' k~ 1 ~/
Mn 0.~%..1%
Irllpl.lrItIC'S<0.5%
This alloy can be cast ~ccordir~g to the differewe methods
mentioned here above. !r~ this example, this alloy is obtairoeci by
sprayforming billets whose diameter is 240mm.
7. Q First_sl_y.g.: the billets arc' extruded for example to a diameter of
ZOmm. If the billets' dimensional irregr.il~ritics are too great, a turning
step
can be necessary before extrr.rsior~. At the exit of the extrusion die, the
alloy
is cooled by water spray allowing a cooling speed of 300°Clmin to
3000"C/min to be achieved, as measr.rred at the center of the alloy. This
snrrr--r-nr.-z-r~~l
CA 02561903 2006-10-02
1z
speed is sufficiently slow to avoid fissuring and sufficiently fast to limit
the
formation o~f a fragilizing second phase. If cooling at the exit of the
extrusion die is clot sufficiently fast, a too great a proportion of second
phase carp form. The alloy will then have to undergo a homogenization
treatment wiOh the same characteristics for the cooling speed at a
temperature within the range where the alloy is one-phased, i.e. beOween
780°C and 920°C for the composition of Uable 3.
Secor~c~,_sly.~g: the material of the first sing at a diameter of 20mrt~
is i~ammc~red to a diameeer o~f 1 1 mm then annealed iro a through-type
furnace. For the alloy with the chemical compositioro of example 3, the
annealing temperature mast be comprised l~e~tween 780°c~ and
920°C. With
a diameter of 1 1 mm end the chemical composition of table 3, a cooling
speed comprised bctwe~rr 300°Clmin and 15000°C/min allows the
presence
of second phase to be lirmited while avoiding fissuring. Use of~ harnmering
allows considerable strain-hardening rates to be achieved, e~er~ with a
fragile material. With ehis rnPthod, the r-emair~der rate of fragilizing
second
phase cars be higher ti~an with rolling, wire-drawing or stretch-forrr,irrg
methods. Il carp reach values on the order of 50% by volume.
Thi_rd___sI_y_gy the material of the s~cor~d slug at a diameter of 1lmm
Z0 is hammered to a diameter of 6,5mm then arvr~ealed iro a ~through,~type
furnace or tempering furnace at a temperature comprised between 780°C
and 970"C. With ~3 di<imeter of f,5mm 'the alloy of table 3 allows cooling
speeds between 300°Clmin to 70000°Cl~~nirv without any
fissr.rring. These
speeds oilow the ratio of fragilizind second phase to be limited.
7S Finishing: the material of the third slug is wire-drawn or stretch-
~formed to a diameter of 4rnrY~ to obtain a rnachinable product. n spinodal
decomposition treatmenO is ~finaily performed on the rnacP~ir~able product
or on the machirved pieces 'to obtain optimal mechanical properties.
sMr_ rai_-z-rec-r
CA 02561903 2006-10-02
13
COO~In(~'_test
Samples of the inventive alloy have beero subjected 'to 'test o'f 'fast
cooling to determine the occurrence of fisstaring. 'fhe chemical corrtposition
of the allay in this test is given by table 2.
The samples were subjected to a heat ~~reatmer~t at a
temperature of 800°C and 'then cooled quickly by immersion in a
tempering
fl~.tid (EXXON XD90) and in water.
I=or each cooling, the cooling sped, in °Clmin, was measured
with a -thermocouple at the center of the sample. The presence of fissuring
was verified by a traction test.
Tabic 5
i
diameOerlmm traction traction test
test
X~'~O 'l"ate
24000 C7 63000 x
U 16000 O 4~35d0
8 12000 O 33000 x
10.8 8300 O -
13 6500 Olx 2300
_...._._ -......
(O - st.lccess I
xu failu.lre)
The test permits to observe ~thwt'the diame'cers up to about 1Umm
can tolerate a coolirvg irt a tempering fluid. Water tsampering, on thc~ other
hand, always leads to o fissuring of the sample, ancf this trp to a minimal
diarz~eter of 4rorn.
I-or srreall~dimer~sion products of Ctn~Ni~Sn~f'b, cooling speeds
c7reoter than 24000°C/min can be used. In this case, water terrrpering
can be
efficient if the prOdlJCt~S 5170-' IS slIffICICntIy small to limit the
transitory
internal constraints and thus prevent fissuring from forr,~ing.
The maGhinable prodtacts of the examples 1, 2, 3 and 4 car? each
be mWe by the methods pf the examples ~, 2, 3 and 4 provided 'that't!'~e
sM rrm_-z-hc_-L.
CA 02561903 2006-10-02
14
cooling speeds and the heat treatment temperatures are adapted to the
chemical compositions and to the dimensions. irn each of the presented
examples, the number ofi slugs can vary according tn the size of the finished
product.
Part of the copper of the alloys ofi the present iroverocion can be
replac.c~d by other elements, for example Fe, Zn or Mn, at a ratio for
C'X~rTlpiC' l-Ip t0 ~in%.
Other elements s~.~ch as Nb, Cr, Mg, Zr and AI can ~Iso be present,
at a ratio t.rp to several percents. These elements have among others the
1U effect of improving the spinodai hardenirog.
sum: rm ..>.f~~_v-
