U.S. patent application number 11/542508 was filed with the patent office on 2007-04-26 for machinable copper-based alloy and production method.
This patent application is currently assigned to SWISSMETAL UMS Usines Metallurgiques Suisse SA. Invention is credited to Emmanuel Vincent.
Application Number | 20070089816 11/542508 |
Document ID | / |
Family ID | 34957563 |
Filed Date | 2007-04-26 |
United States Patent
Application |
20070089816 |
Kind Code |
A1 |
Vincent; Emmanuel |
April 26, 2007 |
Machinable copper-based alloy and production method
Abstract
Alloys based on copper, nickel, tin and lead obtained by a
method of continuous or semi-continuous casting, or static billet
casting or sprayforming billet casting, and capable of spinodal
hardening. The machinability index of the inventive alloys exceeds
80% relatively to standard ASTM C36000 brass and can even reach
90%.
Inventors: |
Vincent; Emmanuel;
(St-Imier, CH) |
Correspondence
Address: |
PEARNE & GORDON LLP
1801 EAST 9TH STREET
SUITE 1200
CLEVELAND
OH
44114-3108
US
|
Assignee: |
SWISSMETAL UMS Usines
Metallurgiques Suisse SA
Reconvillier
CH
CH-2732
|
Family ID: |
34957563 |
Appl. No.: |
11/542508 |
Filed: |
October 3, 2006 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
PCT/EP04/50449 |
Apr 5, 2004 |
|
|
|
11542508 |
Oct 3, 2006 |
|
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|
Current U.S.
Class: |
148/679 ;
148/684 |
Current CPC
Class: |
C22C 9/06 20130101; C22C
9/02 20130101 |
Class at
Publication: |
148/679 ;
148/684 |
International
Class: |
C22F 1/08 20060101
C22F001/08 |
Claims
1. Production method of a metallic product composed of an alloy
comprising between 1% and 20% by weight of Ni, between 1% and 20%
by weight of Sn, between 0.5% and 2% of Pb, the remainder being
constituted essentially of Cu, the method comprising: a heat
treatment comprising a step of heating and homogenizing said alloy,
determining a cooling speed sufficiently slow to prevent fissuring
and sufficiently high to limit the formation of a two-phased
structure, followed by a cooling step at the determined speed.
2. The method of claim 1, wherein said heat treatment is followed
by a step of cold deformation by rolling, wire-drawing,
stretch-forming or hammering.
3. The method of claim 1, wherein said heat treatment is performed
in a through-type furnace.
4. Method according to claim 1, comprising an initial step of
continuous casting followed by a hammering step or an initial step
of static billet casting or a step of sprayforming billet casting,
or a step of semi-continuous billet casting, followed by an
extrusion step.
5. The method of claim 1, wherein said heat treatment takes places
at a temperature comprised between 690.degree. C. and 920.degree.
C.
6. The method of claim 1, wherein the transversal dimension of said
metallic product during said heat treatment is comprised between 1
mm and 100 mm.
7. The method of claim 1, wherein said cooling step of said heat
treatment has a cooling speed comprised between 10.degree. C./min
and 24000.degree. C./min or between 10.degree. C./min and
4000.degree. C./min or between 100.degree. C./min and 1500.degree.
C./min.
8. The method of claim 1, wherein said cooling step of said heat
treatment has a cooling speed comprised between 100.degree. C./min
and 1000.degree. C./min.
9. The method of claim 1, comprising a step of wire-drawing or
stretch-forming or hammering or rolling.
10. The method of claim 1, comprising a step of spinodal
hardening.
11. The method of claim 1, wherein said alloy comprises between 6%
and 8% of Ni, between 4% and 6% of Sn and between 0.5% and 2% of
Pb.
12. The method of claim 1, wherein said alloy comprises between 8%
and 10% of Ni, between 5% and 7% of Sn and between 0.5% and 2% of
Pb.
13. The method of claim 1, wherein said alloy comprises between 14%
and 16% of Ni, between 7% and 9% of Sn and between 0.5% and 2% of
Pb.
14. Product from the method of claim 1.
Description
REFERENCE DATA
[0001] This application is a continuation of International Patent
Application 2004WO-EP050449 (WO05108631) filed on Apr. 5, 2004, the
contents whereof are hereby incorporated.
TECHNICAL FIELD
[0002] The present invention concerns an alloy based on copper,
nickel, tin, lead and its production method. In particular, though
not exclusively, the present invention concerns an alloy based on
copper, nickel, tin, lead easily machined by turning, slicing or
milling.
[0003] STATE OF THE ART
[0004] Alloys based on copper, nickel and tin are known and widely
used. They offer excellent mechanical properties and exhibit a
strong hardening during strain-hardening. Their mechanical
properties are further improved by the known heat-aging treatment
such as spinodal decomposition. For an alloy containing, by weight,
15% of nickel and 8% of tin (standard alloy ASTM C72900), the
mechanical resistance can reach 1500 MPa.
[0005] Another favorable property of the Cu--Ni--S alloys is that
they offer good tribological properties, comparable to those of
bronzes, while exhibiting superior mechanical properties.
[0006] Another advantage of these materials is their excellent
formability, combined with favorable elastic properties. Moreover,
these alloys offer a good resistance against corrosion and an
excellent resistance to the constraints' heat relaxation. For this
reason, the Cu--Ni--Sn springs do not lose their compression force
with age, even under vibrations and strong heat stresses.
[0007] These favorable properties, combined with good heat and
electricity conductivity, mean that these materials are widely used
for making highly reliable connectors for telecommunications and
the car industry. These alloys are also used in several switches
and electrical or electromechanical devices or as supports of
electronic components or for making bearing friction surfaces
subjected to high charges.
[0008] The Cu--Be alloys can be machined fairly well and can
contend with and even outperform the mechanical properties of
Cu--Ni--Sn alloys. The machinability index of the Cu--Be alloys can
reach 50-60% relatively to standard ASTM C36000 brass. Their cost
is however high and their production, use and recycling are
particularly constraining because of the beryllium's high toxicity.
The resistance to the constraints' heat relaxation of these
materials is lower than that of the Cu--Ni--Sn for temperatures
above 150-175.degree. C.
[0009] One inconvenience of the Cu--Ni--Sn alloys is however that
they are poorly suited to processes such as milling, turning or
slicing or to any other known process. A further inconvenience of
these alloys is their strong segregation during casting.
[0010] It is thus an aim of the present invention to propose an
alloy associating the favorable mechanical characteristics of
alloys based on copper, nickel and tin with a good workability.
[0011] It is another aim of the present invention to propose a
method for producing a machinable product on the basis of
Cu--Ni--Sn free from the inconveniences of the prior art.
[0012] It is another aim of the present invention to propose a
machinable alloy combining high elasticity and mechanical
resistance characteristics but free from beryllium or toxic
elements.
[0013] A further aim of the present invention is to propose a
method for producing a machinable product on the basis of
Cu--Ni--Sn allowing the problems relative to segregation to be
solved.
SHORT DESCRIPTION OF THE INVENTION
[0014] These aims are achieved by the product and the method that
are the object of the independent claims of corresponding category
and notably by a machinable product composed of an alloy comprising
between 1% and 20% by weight of Ni, between 1% and 20% by weight of
Sn, between 0.1% and 4% of Pb, the remainder being constituted
essentially of Cu, having undergone a heat homogenizing treatment
comprising a step of heating said alloy followed by a step of
cooling at a speed sufficiently slow to prevent fissuring.
DETAILED DESCRIPTION OF THE INVENTION
[0015] The present invention concerns alloys on the basis of
copper, nickel, tin and lead obtained by a continuous or
semi-continuous casting method, a static billet casting or casting
by sprayforming. The copper-nickel-tin alloys have a long
solidification interval leading to a considerable segregation
during casting. Of the four aforementioned processes, casting by
sprayforming, also known by the name "Osprey" method, and described
for example in patent EP0225732 makes it a possible to obtain an
almost homogenous microstructure presenting a minimal degree of
segregation. In this process, a metal billet is obtained by
continuous depositing of atomized droplets. The segregation can
take place only on the scale of the atomized droplets. The
diffusion distances required for diminishing the segregation are
thus shortened. In the case of continuous or semi-continuous
casting, the segregation is stronger than with the sprayforming
process, but it remains sufficiently reduced to avoid an excessive
fragility of the alloy. The static billet casting leads to a strong
segregation that can be eliminated only by a prolonged heat
processing.
[0016] Lead being essentially insoluble in the other metals of the
alloy, the product obtained will comprise lead particles dispersed
in a Cu--Ni--Sn matrix. During the machining operations, the lead
has a lubricating effect and facilitates the fragmentation of the
slivers.
[0017] The quantity of lead introduced in the alloy depends on the
degree of machinability that one strives to achieve. Generally, a
quantity of lead up to several percents by weight can be introduced
without the alloy's mechanical properties at normal temperature
being modified. However, above the lead melting point (327.degree.
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, on the
other hand, because they can exhibit a two-phased crystallographic
structure containing an undesirable weakening phase.
[0018] The method of the present invention makes it possible to
produce a machinable Cu--Ni--Sn--Pb product containing up to
several percents by weight of lead, without it fissuring during
fabrication, and having excellent mechanical properties. The ratio
of lead can vary between 0.1% and 4% by weight, preferably between
0.2% and 3% by weight, even more preferably between 0.5% and 1.5%
by weight.
[0019] After smelting in the foundry, the production methods can be
decomposed in successive slugs: for the first slug, two cases must
be considered according to whether the product is manufactured by
continuous casting at small diameter or by static billet casting,
sprayforming, semi-continuous or continuous casting at large
diameter.
[0020] The products of the invention are characterized by their
excellent machinability, which is greater than that of Cu--Be
alloys. The machinability index of the inventive alloys exceeds 80%
relatively to standard ASTM C36000 brass and can even reach
90%.
[0021] First Slug:
[0022] Alloys obtained by continuous small-diameter thread casting,
e.g. of 25 mm or less, undergo a heat homogenizing treatment or a
step of cold deformation by hammering followed by a homogenizing
and recrystallization treatment. The temperature of the heat
treatment must be within the range where the alloy is one-phased.
Cooling after the heat treatment must occur at a speed sufficiently
slow to prevent fissuring of the alloy due to internal constraints
generated by the temperature differences during cooling, and
sufficiently fast to limit the formation of a two-phased structure.
If the speed is too slow, a considerable quantity of second phase
can appear. This second phase is very fragile and greatly reduces
the alloy's deformability. The critical cooling speed required to
avoid the formation of too large a quantity of second phase will
depend on the alloy's chemistry and is greater for a higher
quantity of nickel and tin.
[0023] Moreover, during cooling, transitory internal constraints
are generated within the alloy. They are linked to temperature
differences between the surface and the center of the product. If
these constraints exceed the alloy's resistance, the latter will
fissure and is no longer usable. Internal constraints due to
cooling are all the higher the more the product's diameter is
large. The critical cooling speeds to avoid fissuring thus depend
on the product's diameter. This problem is even more acute with
Cu--Ni--Sn--Pb alloys since above its melting temperature of
327.degree. C., lead strongly weakens the alloy.
[0024] In the method of the present invention, cooling after heat
treatment occurs at a predetermined speed taking into account the
alloy's chemistry and the transversal dimension, or diameter, of
the product. The cooling speed must be at the same time
sufficiently slow to prevent fissuring and sufficiently great to
prevent too large a quantity of fragilizing phase to form.
[0025] During manufacture of a large-diameter product, the internal
constraints due to the temperature differences are greater than in
a small-dimension product, and the cooling speed must consequently
be limited. At the same time, strong proportions of Ni and Sn
promote the formation of a fragilizing phase and require a faster
cooling.
[0026] Alloys obtained by sprayforming, static billet casting or
semi-continuous casting undergo a hot extrusion treatment. This is
also the case for continuous casting if the product is of large
diameter. Cooling during extrusion must be sufficiently slow to
prevent fissuring and sufficiently fast to limit the formation of a
fragilizing second phase. Alternatively, if cooling during
extrusion is too slow, heat homogenizing and recrystallization
treatments as explained here above for the case of small-diameter
continuous-casting products must follow extrusion.
[0027] Once the first slug has been made, the final machinable
product must be either obtained directly by one or several cold
deformation operations, e.g. by rolling, wire-drawing,
stretch-forming or any other cold deformation process, or obtained
by one or several successive slugs.
[0028] Successive Slugs:
[0029] From the first slug, the following slugs are obtained by one
or several cold deformation operations followed by a heat
recrystallization treatment. The temperature of the
recrystallization treatment must be within the range where the
alloy is one-phased. Cooling after the heat treatment must have a
speed sufficiently slow to prevent fissuring but always
sufficiently fast to limit the formation of a two-phased structure.
Through successive slugs, the size of the product is reduced. From
the last slug, the final product is obtained by one or several cold
deformation operations.
[0030] The mechanical properties of the alloy obtained can be
subsequently increased by a spinodal decomposition heat treatment.
This treatment can take place before the final machining or after
the latter.
[0031] Hereafter, examples of methods and of machinable products
according to the present invention will be presented. In the
following examples, the cooling temperatures refer to the center of
the product.
EXAMPLE 1
[0032] The chemical composition of the alloy in this example is
given by table 1: TABLE-US-00001 TABLE 1 Proportion (by Component
weight) Cu remainder Ni 7.5% Sn 5% Pb 1% Mn 0.1%-1% other
<0.5%
[0033] Manganese is introduced in the composition as deoxidizer. It
is however possible to use instead other elements or devices
preventing the alloy from oxidizing.
[0034] This alloy can be cast according to the different methods
mentioned further above. In this example, this alloy is obtained by
continuous billet casting with a diameter of 180 mm.
[0035] First slug: the billets are extruded for example to a
diameter of 18 mm. At the exit of the extrusion die, the alloy is
cooled by a stream of compressed air allowing a cooling speed of
50.degree. C./min to 300.degree. C./min to be achieved, as measured
at the center of the alloy. This speed is sufficiently slow to
avoid fissuring and sufficiently fast to limit the formation of a
fragilizing second phase. Cooling by water spray can also be used,
possibly allowing cooling speeds of 300.degree. C./min to
1000.degree. C./min to be achieved without fissuring of the
material. Other means for reaching a suitable cooling speed can
also be used. If cooling at the exit of the extrusion die is not
sufficiently fast, a too great a proportion of second phase can
form, the alloy will have to undergo a homogenization treatment
with the same characteristics for the cooling speed at a
temperature within the range where the alloy is one-phased, i.e.
between 690.degree. C. and 920.degree. C. for the composition of
table 1.
[0036] Second slug: the material of the first slug at a diameter of
18 mm is rolled to a diameter of 13 mm then annealed in a
through-type furnace or removable cover furnace. For the alloy with
the chemical composition of example 1, the annealing temperature
must be comprised between 690.degree. C. and 920.degree. C. A
cooling speed on the order of 10.degree. C./min is sufficient to
limit the formation of second phase for this composition and this
diameter of 13 mm. Furthermore, water spray cooling at speed of
300.degree. C./min to 3000.degree. C./min allows fissuring to be
prevented and the formation of a fragilizing second phase to be
limited.
[0037] Finishing: the material of the second slug is wire-drawn or
stretch-formed to a diameter of 8 mm to obtain a machinable
product. A spinodal decomposition treatment is finally performed on
the machinable product or on the machined pieces to obtain optimal
mechanical properties.
EXAMPLE 2
[0038] The chemical composition of the alloy in this example is
given by table 2: TABLE-US-00002 TABLE 2 Proportion (by Component
weight) Cu remainder Ni 9% Sn 6% Pb 1% Mn 0.1%-1% Impurities
<0.5%
[0039] In this example, this alloy is obtained by continuous thread
casting with a diameter of 18 mm.
[0040] First slug: the thread undergoes a homogenization treatment
in a through-type furnace at a temperature between 700.degree. C.
and 920.degree. C., corresponding to the one-phase range of the
chemical composition of example 2. A cooling speed between
100.degree. C./min and 1000.degree. C./min allows fissuring to be
prevented and the proportion of fragilizing second phase to be
limited. Such cooling speeds can for example be achieved by using
compressed air, water spray or a gas/water exchanging cooler.
[0041] Second slug: the material of the first slug at a diameter of
18 mm is rolled, wire-drawn or stretch-formed to a diameter of 13
mm then annealed in a through-type furnace at a temperature
comprised between 700.degree. C. and 920.degree. C. With a diameter
of 13 mm and the chemical composition of table 2, a cooling speed
between 100.degree. C./min to 3000.degree. C./min allows the
formation of a second phase to be limited while avoiding
fissuring.
[0042] Third slug: the material of the second slug at a diameter of
13 mm is rolled, wire-drawn or stretch-formed to a diameter of 10
mm then annealed in a through-type furnace or tempering furnace at
a temperature comprised between 700.degree. C. and 920.degree. C.
With a diameter of 10 mm and the chemical composition of table 2, a
cooling speed between 100.degree. C./min to 15000.degree. C./min
allows the formation of a second phase to be limited without any
fissuring being created.
[0043] Fourth slug: the material of the third slug at a diameter of
10 mm is rolled, wire-drawn or stretch-formed to a diameter of 7 mm
then annealed in a through-type furnace or tempering furnace at a
temperature comprised between 700.degree. C. and 920.degree. C.
With a diameter of 7 mm and the chemical composition of table 2, a
cooling speed between 100.degree. C./min to 20000.degree. C./min
allows the formation of a fragilizing second phase to be limited
without any fissuring being created.
[0044] Fifth slug: the material of the fourth slug at a diameter of
7 mm is rolled, wire-drawn or stretch-formed to a diameter of 5 mm
then annealed in a through-type furnace or tempering furnace at a
temperature comprised between 700.degree. C. and 920.degree. C.
With a diameter of 5 mm and the chemical composition of table 2, a
cooling speed between 100.degree. C./min to 30000.degree. C./min
allows the formation of a fragilizing second phase to be limited
without any fissuring being created. A cooling speed on the order
of 15000.degree. C./min can be achieved by tempering in appropriate
fluids.
[0045] Sixth slug: the material of the fifth slug at a diameter of
5 mm is rolled, wire-drawn or stretch-formed to a diameter of 3 mm,
annealed in a through-type furnace or tempering furnace at a
temperature comprised between 700.degree. C. and 920.degree. C.,
then cooled at a cooling speed comprised between 100.degree. C./min
to 40000.degree. C./min.
[0046] Seventh slug: the material of the sixth slug at a diameter
of 3 mm is rolled, wire-drawn or stretch-formed to a diameter of 2
mm, annealed in a through-type furnace or tempering furnace at a
temperature comprised between 700.degree. C. and 920.degree. C.,
then cooled at a cooling speed comprised between 100.degree. C./min
to 40000.degree. C./min.
[0047] Eighth slug: the material of the seventh slug at a diameter
of 2 mm is rolled, wire-drawn or stretch-formed to a diameter of
1.60 mm, annealed in a through-type furnace or tempering furnace at
a temperature comprised between 700.degree. C. and 920.degree. C.,
and then cooled at a cooling speed comprised between 100.degree.
C./min to 50000.degree. C./min.
[0048] Finishing: the material of the eighth slug is rolled,
wire-drawn or stretch-formed to a diameter of 1 mm to obtain a
machinable product. A spinodal decomposition treatment is finally
performed on the machinable product or on the machined pieces to
obtain optimal mechanical properties.
[0049] The "ASTM test method for machinability" test proposes a
method for determining the machinability index relatively to
standard CuZn39Pb3, or C36000 brass. The machinability index of the
alloy according to this aspect of the invention is better by
80%.
EXAMPLE 3
[0050] The chemical composition of the alloy in this example is the
same as that of the second example given by table 2. In this
example, the alloy is obtained by continuous casting at a diameter
of 25 mm.
[0051] First slug: the thread cast at a diameter of 25 mm is
hammered to a diameter of 16 mm. The hammering allows the material
to deform with a considerable reduction rate without prior heat
homogenizing treatment. With this method, a high remainder ratio of
fragilizing second phase can be tolerated at this stage. The second
phase can reach a volume ratio on the order of 50%.
[0052] After hammering, the thread at a diameter of 16 mm undergoes
a homogenizing and recrystallization treatment in a through-type
furnace. The temperature of the heat treatment must be comprised
between 700.degree. C. and 920.degree. C. The following cooling
will take place at a speed comprised between 100.degree. C./min and
3000.degree. C./min. These cooling speeds make it possible to
prevent fissuring and to limit the ratio of second phase for a
product of this diameter and of this composition. Such speeds can
be obtained by using compressed air, water spray or gas/water
exchangers.
[0053] Finishing: the material of the first slug is wire-drawn or
stretch-formed to a diameter of 10 mm to obtain a machinable
product. A spinodal decomposition treatment is finally performed on
the machinable product or on the machined pieces to obtain optimal
mechanical properties.
EXAMPLE 4
[0054] The chemical composition of the alloy in this example is
given by table 3: TABLE-US-00003 TABLE 3 Proportion (by Component
weight) Cu remainder Ni 15% Sn 8% Pb 1% Mn 0.1%-1% Impurities
<0.5%
[0055] This alloy can be cast according to the different methods
mentioned here above. In this example, this alloy is obtained by
sprayforming billets whose diameter is 240 mm.
[0056] First slug: the billets are extruded for example to a
diameter of 20 mm. If the billets' dimensional irregularities are
too great, a turning step can be necessary before extrusion. At the
exit of the extrusion die, the alloy is cooled by water spray
allowing a cooling speed of 300.degree. C./min to 3000.degree.
C./min to be achieved, as measured at the center of the alloy. This
speed is sufficiently slow to avoid fissuring and sufficiently fast
to limit the formation of a fragilizing second phase. If cooling at
the exit of the extrusion die is not sufficiently fast, a too great
a proportion of second phase can form. The alloy will then have to
undergo a homogenization treatment with the same characteristics
for the cooling speed at a temperature within the range where the
alloy is one-phased, i.e. between 780.degree. C. and 920.degree. C.
for the composition of table 3.
[0057] Second slug: the material of the first slug at a diameter of
20 mm is hammered to a diameter of 11 mm then annealed in a
through-type furnace. For the alloy with the chemical composition
of example 3, the annealing temperature must be comprised between
780.degree. C. and 920.degree. C. With a diameter of 11 mm and the
chemical composition of table 3, a cooling speed comprised between
300.degree. C./min and 15000.degree. C./min allows the presence of
second phase to be limited while avoiding fissuring. Use of
hammering allows considerable strain-hardening rates to be
achieved, even with a fragile material. With this method, the
remainder rate of fragilizing second phase can be higher than with
rolling, wire-drawing or stretch-forming methods. It can reach
values on the order of 50% by volume.
[0058] Third slug: the material of the second slug at a diameter of
11 mm is hammered to a diameter of 6.5 mm then annealed in a
through-type furnace or tempering furnace at a temperature
comprised between 780.degree. C. and 920.degree. C. With a diameter
of 6.5 mm the alloy of table 3 allows cooling speeds between
300.degree. C./min to 20000.degree. C./min without any fissuring.
These speeds allow the ratio of fragilizing second phase to be
limited.
[0059] Finishing: the material of the third slug is wire-drawn or
stretch-formed to a diameter of 4 mm to obtain a machinable
product. A spinodal decomposition treatment is finally performed on
the machinable product or on the machined pieces to obtain optimal
mechanical properties.
[0060] Cooling Test
[0061] Samples of the inventive alloy have been subjected to test
of fast cooling to determine the occurrence of fissuring. The
chemical composition of the alloy in this test is given by table
2.
[0062] The samples were subjected to a heat treatment at a
temperature of 800.degree. C. and then cooled quickly by immersion
in a tempering fluid (EXXON XD90) and in water.
[0063] For each cooling, the cooling speed, in .degree. C./min, was
measured with a thermocouple at the center of the sample. The
presence of fissuring was verified by a traction test.
TABLE-US-00004 TABLE 5 speed speed traction diameter/mm XD90
traction test water test 4 24000 .largecircle. 63000 X 6 16000
.largecircle. 48500 X 8 12000 .largecircle. 33000 X 10.8 8350
.largecircle. -- X 13 6500 .largecircle./X 23500 X (.largecircle. =
success/X = failure)
[0064] The test permits to observe that the diameters up to about
10 mm can tolerate a cooling in a tempering fluid. Water tempering,
on the other hand, always leads to a fissuring of the sample, and
this up to a minimal diameter of 4 mm.
[0065] For small-dimension products of Cu--Ni--Sn--Pb, cooling
speeds greater than 24000.degree. C./min can be used. In this case,
water tempering can be efficient if the product's size is
sufficiently small to limit the transitory internal constraints and
thus prevent fissuring from forming.
[0066] The machinable products of the examples 1, 2, 3 and 4 can
each be made by the methods of the examples 1, 2, 3 and 4 provided
that the cooling speeds and the heat treatment temperatures are
adapted to the chemical compositions and to the dimensions. In each
of the presented examples, the number of slugs can vary according
to the size of the finished product.
[0067] Part of the copper of the alloys of the present invention
can be replaced by other elements, for example Fe, Zn or Mn, at a
ratio for example up to 10%.
[0068] Other elements such as Nb, Cr, Mg, Zr and Al can also be
present, at a ratio up to several percents. These elements have
among others the effect of improving the spinodal hardening.
* * * * *