U.S. patent application number 12/219132 was filed with the patent office on 2008-11-20 for soft copper alloy, and soft copper wire or plate material.
This patent application is currently assigned to Hitachi Cable, Ltd.. Invention is credited to Seigi Aoyama, Yuju Endo, Hiroyoshi Hiruta.
Application Number | 20080283159 12/219132 |
Document ID | / |
Family ID | 37567613 |
Filed Date | 2008-11-20 |
United States Patent
Application |
20080283159 |
Kind Code |
A1 |
Aoyama; Seigi ; et
al. |
November 20, 2008 |
Soft copper alloy, and soft copper wire or plate material
Abstract
A method of fabricating soft copper alloy wire having flexure
resistance and heat resistance, includes casting a molten alloy of
a copper alloy including 10 mass ppm or less of oxygen, and 0.005
mass % to 0.6 mass % of indium, at a predetermined temperature, to
provide a cast bar of the copper alloy having equiaxed crystal,
rolling the cast bar of the copper alloy having equiaxed crystal to
provide a rolled copper alloy, and conducting a cold drawing and
annealing on the rolled copper alloy.
Inventors: |
Aoyama; Seigi; (Ibaraki,
JP) ; Endo; Yuju; (Hitachi, JP) ; Hiruta;
Hiroyoshi; (Ibaraki, JP) |
Correspondence
Address: |
MCGINN INTELLECTUAL PROPERTY LAW GROUP, PLLC
8321 OLD COURTHOUSE ROAD, SUITE 200
VIENNA
VA
22182-3817
US
|
Assignee: |
Hitachi Cable, Ltd.
Tokyo
JP
|
Family ID: |
37567613 |
Appl. No.: |
12/219132 |
Filed: |
July 16, 2008 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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11159417 |
Jun 23, 2005 |
|
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12219132 |
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Current U.S.
Class: |
148/554 ;
164/76.1 |
Current CPC
Class: |
C22C 9/00 20130101 |
Class at
Publication: |
148/554 ;
164/76.1 |
International
Class: |
C22F 1/08 20060101
C22F001/08; B22D 23/00 20060101 B22D023/00 |
Claims
1. A method of fabricating soft copper alloy wire having flexure
resistance and heat resistance, comprising: casting a molten alloy
of a copper alloy comprising 10 mass ppm or less of oxygen, and
0.005 mass % to 0.6 mass % of indium, at a predetermined
temperature, to provide a cast bar of the copper alloy having
equiaxed crystal; rolling the cast bar of the copper alloy having
equiaxed crystal to provide a rolled copper alloy; and conducting a
cold drawing and annealing on the rolled copper alloy.
2. The method for fabricating soft copper alloy wire having flexure
resistance and heat resistance, according to claim 1, wherein a
temperature of molten alloy in casting is 10.degree. C. to
50.degree. C. greater than a melting temperature of the copper
alloy.
3. The method for fabricating soft copper alloy wire having flexure
resistance and heat resistance, according to claim 1, wherein the
copper alloy further comprises 0.0001 mass % to 0.003 mass % of
phosphorus.
4. The method for fabricating soft copper alloy wire having flexure
resistance and heat resistance, according to claim 1, wherein the
copper alloy further comprises 0.01 mass % to 0.1 mass % of
boron.
5. The method for fabricating soft copper alloy wire having flexure
resistance and heat resistance, according to claim 1, wherein the
copper alloy includes phosphorus and boron together in a range of
0.1 mass % or less.
6. The method for fabricating soft copper alloy wire having flexure
resistance and heat resistance, according to claim 1, wherein the
indium included in the copper alloy is 0.1 mass % to 0.2 mass
%.
7. The method of fabricating soft copper alloy wire having flexure
resistance and heat resistance, according to claim 1, wherein the
annealing is conducted after the cold drawing, wherein an average
crystal gain size after annealing is in a range from 2 .mu.m to 20
.mu.m.
Description
RELATED APPLICATIONS
[0001] The present Application is a Divisional Application of U.S.
patent application Ser. No. 11/159,417, which was filed on Jun. 23,
2005.
[0002] The present application is based on Japanese patent
application No. 2004-159183, the entire contents of which are
incorporated herein by reference.
BACKGROUND OF THE INVENTION
[0003] 1. Field of the Invention
[0004] The present invention relates to a soft copper alloy as
conductive material, and a soft copper alloy wire or plate
material.
[0005] 2. Description of the Related Art
[0006] In modern science and technology, electricity is used in all
parts including electric power as source of power and electrical
signals, and to transmit electricity, conductors such as cables and
leadwires are used. Materials for such conductors include copper,
silver and other metals of high conductivity, and in particular
copper wires are used most widely in consideration of cost and
other aspects.
[0007] Copper may be roughly classified into hard copper and soft
copper depending on its molecular arrangement, and various types of
copper having desired properties are used depending on the
application and purpose.
[0008] For example, in cables connected to driving parts of
industrial robot or automatic machine tool, rigid and hard copper
wire is not suited, and soft copper wire is used.
[0009] In lead wires for electronic components, hard copper wires
are used, because, once connected, they are not detached and moved
again, and it is desired to prevent deformation when
connecting.
[0010] In any copper wire, additive-free copper is rarely used, and
a proper amount of additive having a desired property is often
added, and the molecular structure is also controlled.
[0011] For example, heat resistance or mechanical characteristic
will be enhanced by adding indium or tin, as compared with pure
copper, but if added too much, the conductivity may be lowered.
[0012] Or, as the oxygen content in copper increases, conductivity
or cold workability may be lowered, or by forming an oxide by
reaction with an additive, wire breakage is likely to occur when
forming an ultrathin wire.
[0013] To solve these problems, so far, various methods have been
proposed (see, for example, Japanese Patent Application Laid-Open
(JP-A) No. 2002-363668 and JP-A No. 9-256084).
[0014] However, much has not been studied yet about soft copper
wires. For example, the invention disclosed in JP-A No. 2002-363668
is an invention about hard copper wire, and flexure resistance is
not specifically evaluated, nothing is studied about soft copper
wire which is superior in flexure resistance. Heat resistance is
not evaluated either.
[0015] Although the invention of JP-A No. 9-256084 is an invention
about soft copper alloy, the crystal grain size after annealing is
specified to be 1.6 um or less. The manufacturing condition is very
difficult to maintain the crystal grain size at this level, and
although the properties are excellent, it is not practical to
realize this because of too many economical loads.
[0016] The invention is devised in the light of above background,
and it is hence an object thereof to provide a conductive material
having both flexure resistance and heat resistance suitable to
application into flexure-resistant conductive materials such as
power distribution wires, vehicle wires and robot wires.
SUMMARY OF THE INVENTION
[0017] It is an object of the invention to provide a conductive
material having both flexure resistance and heat resistance
suitable to application into flexure-resistant conductive materials
such as power distribution wires, vehicle wires and robot
wires.
[0018] According to one aspect of invention, a soft copper alloy
comprises:
[0019] 10 mass ppm or less of oxygen; and
[0020] more than 0.005 mass % and less than 0.6 mass % of
indium.
[0021] The soft copper alloy may further comprising 0.0001 to 0.003
mass % of phosphorus.
[0022] The softer copper alloy may further comprise 0.001 to 0.1
mass % of boron.
[0023] The soft copper alloy may further comprise phosphorus and
boron together in a range of 0.1 mass % or less.
[0024] It is preferred that a temperature of molten alloy in
casting is 10 to 50 degrees higher than a melting point of the
alloy so that a crystal structure in cast bar comprises an equiaxed
crystal.
[0025] According to another aspect of the invention, provided is a
soft copper alloy wire or plate material manufactured by processing
the soft copper alloy, wherein an average crystal grain size after
annealing is 2 to 20 um.
[0026] It is preferred that 0.2% proof strength is 130 MPa or
more.
[0027] It is preferred that tin or Mg or Ag is included in a range
of a conductivity not lower than 85% IACS.
[0028] It is preferred that a tensile strength after heating for 1
hour at 400.degree. C. is within 4%.
[0029] Thus, according to the invention, a soft copper alloy wire
suppressed in decline of conductivity and having excellent flexure
resistance and heat resistance can be provided, and it is expected
to extend the service life of conductive materials when used in
flexure resistant conductive materials such as power distribution
wires, vehicle wires or robot wires.
BRIEF DESCRIPTION OF THE DRAWINGS
[0030] The preferred embodiments according to the invention will be
explained below referring to the drawings, wherein:
[0031] FIG. 1 is a metallographic cross-section view of crystal
structure, showing a cast bar of columnar crystal and a cast bar of
equiaxed crystal; and
[0032] FIG. 2 is a cross-section view comparing crystal structure
between a copper alloy of the invention and a comparative material
of pure copper.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0033] Copper alloys in preferred embodiments of the invention are
explained below.
[Quality of Cast Bar and Rough Drawn Wire]
[0034] Qualify of rough drawn wire obtained by continuous casting
is determined by the state of texture of copper alloy in the cast
bar before processing. Therefore, in order to manufacture an alloy
wire of copper-indium system at a stable quality usable
industrially, it is required to control the texture in a stage of
cast bar.
[0035] Table 1 compares the state of texture and quality of rough
drawn wires obtained from cast bars when cast bars were
manufactured in several different conditions. Herein, the casting
speed was 30 tons/h, and wires were cast and cooled by using a
casting ring made of copper. Continuous casting and rolling was
operated by SCR system.
[0036] In this embodiment, all wires were continuously cast and
rolled by SCR system, but the invention is not limited to this
system, may be realized by Hazley type continuous casting and
rolling system or other manufacturing method.
TABLE-US-00001 TABLE 1 Contained Contained Element: Element: Molten
copper alloy Sample oxygen Indium temperature (above Cast bar
Quality of rough No. (mass ppm) (mass %) melting point (deg.)
texture drawn wire 1 8 0.1 and 0.2 100 to 70 columnar X (too many
crystal flaws to make product) 2 9 0.1 and 0.2 45 equiaxed
.circleincircle. (excellent) crystal 3 7 0.1 and 0.2 30 equiaxed
.circleincircle. (excellent) crystal 4 10 0.1 and 0.2 10 equiaxed
.largecircle. (slight flaws) crystal 5 8 0.1 and 0.2 5 machine --
(no product) stop
[0037] Generally, molten copper temperature when manufacturing
copper or copper alloy is preferably said to be higher than the
melting point by 50 degrees or more, but as known from the results
in Table 1, rough drawn wires of favorable quality could be
obtained at the molten copper alloy temperature higher than melting
point by 10 degrees to 45 degrees only. Thus, even if the molten
copper alloy temperature is not higher than the melting point by 50
degrees or more, it is known that favorable rough drawn wires can
be obtained. However, if the molten copper alloy temperature was
not higher than the melting point by 5 degrees or more, the machine
stopped and products could not be obtained. In the cast bar when
obtaining favorable rough drawn wires, the texture of copper alloy
was equiaxed crystal. Hence, to obtain rough drawn wires of
favorable quality, it is desired to use cast bars made of copper
alloy having equiaxed crystal, and further to manufacture cast bars
made of copper alloy having equiaxed crystal, it is preferred to
set the molten copper temperature at 10 to 50 degrees higher than
the melting point when casting. More preferably, the molten copper
temperature should be set at 10 to 45 degrees higher than the
melting point when casting.
[0038] In any example in Table 1, additives such as phosphorus and
boron are not included, but in this copper-indium alloy system,
similar effects could be obtained regardless of presence or absence
of trace elements such as phosphorus and boron.
[0039] Comparative cross-section view of cast texture sections is
shown in FIG. 1.
[Study on Conductivity of Copper Alloy Wire]
[0040] To determine favorable compositions in copper alloy of the
invention, alloys of several different compositions were tested,
and results are shown in Table 2.
TABLE-US-00002 TABLE 2 Oxygen Proof Sample In P B concentration
Conductivity strength Crystal Heat Overall No. (mass %) (mass %)
(mass %) (mass ppm) (% IACS) (Mpa) gain size resistance evaluation
1 0 7 101.5 102 X X X 2 0.005 8 100.8 122 X X X 3 0.01 9 100.2 140
.largecircle. .largecircle. .largecircle. 4 0.02 7 100 145
.largecircle. .largecircle. .largecircle. 5 0.05 7 99.5 148
.largecircle. .largecircle. .largecircle. 6 0.1 8 98 150
.largecircle. .largecircle. .circleincircle. 7 0.2 9 94 152
.largecircle. .largecircle. .circleincircle. 8 0.3 7 92 155
.largecircle. .largecircle. .circleincircle. 9 0.5 6 90 160
.largecircle. .largecircle. .largecircle. 10 0.6 8 85 162
.largecircle. .largecircle. .largecircle. 11 0.7 9 83 163
.largecircle. .largecircle. X 12 0.15 0.05 8 95 156 .largecircle.
.largecircle. .largecircle. 13 0.3 0.0003 0.05 7 91 160
.largecircle. .largecircle. .largecircle. 14 0.1 0.0003 9 98 155
.largecircle. .largecircle. .largecircle.
[0041] In Table 2, the crystal grain size was evaluated to be
approved (o) when 20 um or less, and rejected (x) when exceeding 20
um. The heat resistance was approved (o) when the strength decline
was within 4% after heating test for 1 hour at 400.degree. C., and
rejected (x) if exceeding this value. The overall evaluation was
excellent (.circleincircle.), fair (.smallcircle.) or poor (x).
[0042] Test results in Table 2 were obtained from rough drawn wires
of 8 mm in diameter manufactured by SCR casting and rolling from
cast bar obtained in the range of appropriate conditions in Table
1. The wires were further cold drawn to diameter of 1.2 mm. In the
drawing process, the wires were electrically annealed in the
condition of speed of 220 m/min and annealing voltage of 24 V or
more.
[0043] In alloy wires not containing other additives than indium,
properties were compared by different contents of indium.
[0044] Comparing samples 1 to 11, along with increase of indium
content, the conductivity dropped and the proof strength of soft
copper alloy wire was improved. Generally, in soft copper alloy
wire, the conductivity is preferred to be 85% IACS or more, and
according to this standard, sample 1 to sample 10 satisfied the
standard, but sample 11 failed to satisfy. Considering from these
results, in the copper alloy of the invention, a preferred indium
content is 0.6 mass % at maximum.
[0045] Besides, 0.2% proof strength having effects on flexure life
indicates values of 110 to 120 MPa generally in tempered pure
copper (TPC), and each value of sample 2 to sample 11 exceeded the
average value of pure copper.
[0046] Hence, sample 2 to sample 10 satisfy the standard as copper
alloy of the invention from the viewpoint of conductivity and soft
copper alloy wire proof strength, and the specified condition is
the indium content of 0.005 to 0.6 mass %.
[0047] When the indium content is in the above range, favorable
properties are shown, and this reason is as follows: in
copper-indium system alloy, characteristics are improved as
compared with copper alone because indium is present in the copper
as solid solution element. When indium existing in copper as solid
solution element increases, the mechanical properties of copper
alloy can be improved, while the conductivity of copper alloy is
lowered on the other hand.
[0048] Specifically, when the indium content is less than 0.005
mass %, characteristic improvement as solid solution element is not
obtained, and hence indium content of 0.005 mass % or more is
needed, but if the indium content is 0.6 mass % or more, the
conductivity is lowered below the standard value.
[0049] Hence, the indium content of copper alloy wire in the
invention is desired to be 0.005 to 0.6 mass %.
[Study on Oxygen Content of Copper Alloy Wire]
[0050] In continuous casting and rolling method, the amount of
oxygen contained in copper alloy is preferred to be 10 mass ppm or
less. The reason is, although the characteristics are improved in
copper-indium system alloy more than in copper alone as mentioned
above, that increase of oxygen content while indium is present as
solid solution element in copper causes to form an oxide of indium,
which does not contribute to improvement of characteristics.
[0051] In the copper alloy of the invention, the standard value of
oxygen content is 10 mass ppm or less.
[Study on Crystal Grain Size of Copper Alloy Wire]
[0052] Crystal grain size varies with content of additives, and
with manufacturing condition of alloy wire. The smaller the crystal
grain size, the higher the mechanical property, especially the
proof strength becomes. When the crystal grain size becomes 20 um
or more, the proof strength is lowered, and it is not desired in
the invention. Depending on the alloy composition or manufacturing
condition, for example, the crystal grain size may be 20 um or
more. On the other hand, if the crystal grain size is 2 um or more,
excellent mechanical characteristics will be obtained, but the
manufacturing condition is difficult for achieving this level, and
it is not suited to mass production. Accordingly, in the invention,
the crystal grain size of the copper alloy is specified in range of
2 to 20 um.
[0053] As shown in the evaluation of crystal grain size in Table 2,
in the case the indium content in copper alloy is 0.005 mass % or
less, the crystal grain size is 20 um or more and it is rejected,
but when contained by 0.01 mass %, the crystal grain size is 20 um
or less, and it is approved. Hence, in the copper alloy of the
invention, a preferred indium content is 0.01 to 0.6 mass %.
[0054] FIG. 2 shows a crystal structure of sample 1 and sample 6 in
Table 2. It is known that the product of the invention is small in
crystal grain size and excellent in texture.
[Study on Heat Resistance of Copper Alloy Wire]
[0055] Heat resistance was studied. The evaluation standard of heat
resistance in the copper alloy of the invention is that drop of
strength should be within 4% after heating for 1 hour at
400.degree. C.
[0056] Using the copper alloy of the invention, the strength after
heating tests in various conditions was measured, and results are
summarized in Table 3.
TABLE-US-00003 TABLE 3 Heating temperature (.degree. C.) before the
test 250 300 400 500 550 Strength (Mpa) after heating test (1 hour)
(value in parentheses shows a ratio compared with strength before
the test) Embodiment 248 248 248 249 250 253 Cu-0.1 mass % (1) (1)
(1) (1.004) (1.008) (1.020) In Comparative 248 246 245 242 238 235
material pure (1) (0.991) (0.989) (0.976) (0.960) (0.948) copper
(TPC) Strength (Mpa) after heating test (10 hours) (value in
parentheses shows a ratio compared with strength before the test)
Embodiment 248 246 246 246 246 246 Cu-0.1 mass % (1) (0.992)
(0.992) (0.992) (0.992) (0.992) In Comparative 248 243 242 236 232
227 material pure (1) (0.980) (0.976) (0.952) (0.935) (0.915)
copper (TPC)
[0057] The sample used in the heat resistance test was hardly
changed in strength after heating for 1 hour at 400.degree. C., and
it was sufficiently approved. When temperature condition was
changed after heating test, the strength was hardly changed, and
the change was extremely small as compared with pure copper used as
comparative example.
[0058] When the testing time was extended to 10 hours, the strength
after heating test was hardly changed, and the copper alloy of the
invention has been confirmed to have an excellent heat
resistance.
[0059] As shown in the evaluation of heat resistance in Table 2, in
the case the indium content in copper alloy is 0.005 mass % or
less, the heat resistance did not satisfy the standard, but when
contained by 0.01 mass %, the heat resistance satisfied the
standard and was approved. Hence, in the copper alloy of the
invention, the indium content is more preferably 0.01 to 0.6 mass
%.
[Study on Concentration Range of Phosphorus and Boron in Copper
Alloy Wire]
[0060] Other elements were added to copper-indium system alloy, and
effects were studied.
[0061] Addition of boron to copper alloy was very useful for
pulverization of crystal, having no effect of lowering the
conductivity. As one of the embodiments of the copper alloy of the
invention, sample 12 in Table 2 is shown as an example of adding
boron.
[0062] The indium content of sample 12 is 0.15 mass %, and there is
no comparative sample of same indium content, but when compared
with sample 6 of indium content of 0.1 mass % and sample 7 of
indium content of 0.2 mass %, the value of conductivity of sample
12 is an intermediate value of conductivity of sample 6 and sample
7, and it is known that the conductivity of copper alloy is not
changed by addition of boron. On the other hand, the value of proof
strength of sample 12 is higher than either value of proof strength
of sample 6 and sample 7, and it is known that addition of boron
contributes to enhancement of proof strength of copper alloy.
[0063] When the addition of boron is slight, sufficient
pulverization effect of crystal is not obtained, but when too much
boron is added, troubles are likely to occur at the time of
casting. Hence, a proper range of addition of boron in the
invention is 0.01 to 0.1 mass %.
[0064] Addition of phosphorus to copper alloy is effective in
preventing blow holes and enhancing the equality of cast material,
and is useful for improving the surface quality of rough drawn
wire. As an embodiment of copper alloy of the invention, phosphorus
is added in sample 14 shown in Table 2.
[0065] The indium content of sample 14 is 0.1 mass %, and when
compared with comparative example of sample 6 having same indium
content, the value of conductivity of sample 14 is same as
conductivity of sample 6, and it is known that the conductivity of
copper alloy is not changed by addition of phosphorus in sample 14.
On the other hand, the value of proof strength of sample 14 is
higher than the proof strength of sample 6, and it is known that
addition of phosphorus contributes to enhancement of proof strength
of copper alloy, and it seems to be due to effect of enhancing the
quality of cast material.
[0066] To obtain such effect, phosphorus must be added by 0.0001
mass % or more, but at content of 0.003 mass %, the conductivity is
lowered by about 2.2% as compared with additive-free sample. It is
not desired to add phosphorus by 0.003 mass % or more because the
conductivity is lowered. Hence, a standard range of addition of
phosphorus in the copper alloy of the invention is 0.0001 to 0.003
mass %.
[0067] Both boron and phosphorus were added to copper alloy in
sample 13 in Table 2.
[0068] The indium content of sample 13 is 0.3 mass %, and when
compared with comparative example of sample 8 of same indium
content, the value of conductivity of sample 13 is almost same as
conductivity of sample 8, and the value of proof strength of sample
13 is higher than the proof strength of sample 8, and it is known
that addition of both boron and phosphorus is known to contribute
to enhancement of proof strength of copper alloy, without causing
any particular adverse effect.
[0069] Summing up these results, an appropriate composition of
copper alloy of the invention comprises an oxygen content of 10
mass ppm or less, and an indium content of 0.005 to 0.6 mass % in
consideration of conductivity and proof strength, or 0.01 to 0.6
mass % in consideration of also crystal grain size and heat
resistance. Boron and phosphorus are not always necessary, but when
added, boron is desired to be added by 0.01 to 0.1 mass %, and
phosphorus by 0.0001 to 0.003 mass %.
[0070] Other elements are known not to contribute to enhancement of
properties of copper alloy, and are not particularly demanded.
However, in the manufacturing field of copper alloy, entry of other
elements may occur. Possible elements include tin, magnesium and
silver. By entry of these elements, drop of mechanical
characteristic is hardly possible, but the conductivity may be
lowered. Accordingly, in a range of conductivity of copper alloy
not becoming lower than 85% IACS, copper alloys including such
elements, tin, magnesium or silver, are considered to be included
in the scope of the invention.
[Study on Proof Strength of Copper Alloy Wire]
[0071] The copper alloy wire of the invention is required to have a
long flexure life. In copper alloy wires differing in 0.2% proof
strength, flexure life was measured, and results are shown in Table
4.
TABLE-US-00004 TABLE 4 0.2% proof Flexture life strength
(distortion Flexture life ratio (as Sample (Mpa) 0.5%) compared to
TPC at 1) Pure copper 110 5.012 1.0 (TPC) Cu-0.1 mass % In 131
7.523 1.5 (anneal 1) Cu-0.1 mass % In 159 12.012 2.4 (anneal 2)
Cu-0.1 mass % In 182 15.009 3.0 (anneal 3) Cu-0.1 mass % In 199
18.112 3.6 (anneal 4)
[0072] The flexure life was measured by using copper alloy wire of
0.1 mm in diameter, in the condition of bending distortion of 0.5%,
load of 32 g, and right and left 90-degree bending of 4
sec/way.
[0073] Proof strength of pure copper is generally about 100 to 120
MPa, and it was 110 MPa in pure copper used as comparative material
in the present test. By contrast, in copper alloys of the
invention, high values of proof strength were obtained although
slightly different depending on annealing conditions, and the
flexure life was also extended along with improvement of proof
strength.
[0074] Comparing a sample with 0.2% proof strength of 131 MPa and a
comparative example with proof strength of 110 MPa, the flexure
life is increased to about 1.5 times, and this result is sufficient
for the purpose of extending the flexure life. Hence, the desired
value of 0.2% proof strength in the copper alloy wire of the
invention is 130 MPa or more.
[Electric Annealer Condition]
[0075] As mentioned above, an electric annealer was used when
drawing from a rough drawn wire in manufacture of copper alloy wire
in the invention. A test was conducted to determine an appropriate
electric annealer condition for the invention.
[0076] The speed was fixed at 220 m/min, and the annealing voltage
of the electric annealer was varied, and in the obtained copper
alloy wires, the tensile strength, 0.2% proof strength and
elongation were measured, and results are shown in Table 5. These
copper alloys are copper-0.1 mass % indium alloys.
TABLE-US-00005 TABLE 5 0.2% proof Anneal voltage Tensile strength
(V) strength (Mpa) (Mpa) Elongation (%) 20 455 450 1.0 22 360 350
2.0 24 295 230 14 25 265 170 17 26 259 154 23 27 251 135 31 28 250
133 32 TPC 240 124 31 comparative material
[0077] Approval standard values were set at elongation of 10% or
more and 0.2% proof strength of 125 MPa or more, and samples in an
annealing voltage range of 24 V to 28 V satisfied the standard. At
over 28 V, the experiment could not be conducted due to limit of
the equipment.
[0078] This experiment was carried out by using an electric
annealer excellent in productivity, but by traveling annealing by
using a tubular electric furnace, it seems that copper alloy wires
having more stable elongation and proof strength as compared with
in the present test results will be obtained.
[0079] Although the invention has been described with respect to
the specific embodiments for complete and clear disclosure, the
appended claims are not to be thus limited but are to be construed
as embodying all modifications and alternative constructions that
may occur to one skilled in the art which fairly fall within the
basic teaching herein set forth.
* * * * *