U.S. patent application number 12/003723 was filed with the patent office on 2010-11-04 for high strength titanium copper alloy, manufacturing method therefor, and terminal connector using the same.
This patent application is currently assigned to NIPPON MINING & METALS CO., LTD.. Invention is credited to Tositeru Nonaka, Takahiro Umegaki, Michiharu Yamamoto.
Application Number | 20100276037 12/003723 |
Document ID | / |
Family ID | 26609695 |
Filed Date | 2010-11-04 |
United States Patent
Application |
20100276037 |
Kind Code |
A1 |
Yamamoto; Michiharu ; et
al. |
November 4, 2010 |
High strength titanium copper alloy, manufacturing method therefor,
and terminal connector using the same
Abstract
A high strength titanium copper alloy consists of Ti at 2.0% by
mass or more to 3.5% by mass or less; the balance of copper and
inevitable impurities; an average grain size of 20 .mu.m or less;
and a 0.2% proof stress expressed by "b" of 800 N/mm.sup.2 or more.
The alloy further comprises a bending radius ratio (bending
radius/sheet thickness) not causing cracking as expressed by "a" by
a W-bending test in a transverse direction to a rolling direction,
wherein "a" and "b" satisfy a.ltoreq.0.05.times.b-40
Inventors: |
Yamamoto; Michiharu;
(Hitachi, JP) ; Nonaka; Tositeru; (Hitachi,
JP) ; Umegaki; Takahiro; (Koza-gun, JP) |
Correspondence
Address: |
OLIFF & BERRIDGE, PLC
P.O. BOX 320850
ALEXANDRIA
VA
22320-4850
US
|
Assignee: |
NIPPON MINING & METALS CO.,
LTD.
TOKYO
JP
|
Family ID: |
26609695 |
Appl. No.: |
12/003723 |
Filed: |
December 31, 2007 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
10076433 |
Feb 19, 2002 |
|
|
|
12003723 |
|
|
|
|
Current U.S.
Class: |
148/501 ;
148/432; 148/434; 148/682 |
Current CPC
Class: |
C22F 1/08 20130101; C22C
9/00 20130101 |
Class at
Publication: |
148/501 ;
148/432; 148/434; 148/682 |
International
Class: |
C21D 11/00 20060101
C21D011/00; C22C 9/00 20060101 C22C009/00; C22C 9/04 20060101
C22C009/04; C22F 1/08 20060101 C22F001/08 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 20, 2001 |
JP |
2001-043278 |
Mar 29, 2001 |
JP |
2001-094522 |
Claims
1. A high strength titanium copper alloy consisting of Ti at 2.0%
by mass or more to 3.5% by mass or less; the balance of copper and
inevitable impurities; and the average grain size of 5 to 15 .mu.m;
the alloy further comprising a 0.2% proof stress expressed by "b"
of 800 N/mm.sup.2 or more; an electrical conductivity of 12.5 to
15.3% IACS; and a bending radius ratio (bending radius/sheet
thickness) not causing cracking as expressed by "a" by a W-bending
test in a transverse direction to a rolling direction; wherein "a"
and "b" satisfy a.ltoreq.0.05.times.b-40, the titanium copper alloy
is obtained by performing final recrystallization annealing at a
temperature below a borderline temperature T of an .alpha.-phase
and an .alpha.+Cu.sub.3Ti phase, and when the borderline
temperature T is approximated in formula y=50x+650, where x (%) is
the concentration of Ti, the final recrystallization annealing is
performed at a temperature ranging from (T-60).degree. C. to
(T-10).degree. C.
2. A high strength titanium copper alloy consisting of Ti at 2.0%
by mass or more to 3.5% by mass or less; at least one of Zn, Cr,
Zr, Fe, Ni, Sn, In, Mn, P, and Si at 0.01% by mass or more to 3.0%
by mass or less in total; and the balance of copper and inevitable
impurities; the alloy further comprising an average grain size of
20 .mu.m or less; a 0.2% proof stress expressed by "b" of 800
N/mm.sup.2 or more; and a bending radius ratio (bending
radius/sheet thickness) not causing cracking as expressed by "a" by
a W-bending test in a transverse direction to a rolling direction;
wherein "a" and "b" satisfy a.ltoreq.0.05.times.b-40.
3. The high strength titanium copper alloy according to claim 2,
wherein the titanium copper alloy is obtained by performing final
recrystallization annealing at a temperature below a borderline of
an .alpha.-phase and an .alpha.+Cu.sub.3Ti phase.
4. A manufacturing method for a high strength titanium copper alloy
according to claim 1, characterized by performing final
recrystallization annealing at a temperature below a borderline of
an .alpha.-phase and an .alpha.+Cu.sub.3Ti phase.
5. A manufacturing method for a high strength titanium copper alloy
according to claim 2, characterized by performing final
recrystallization annealing at a temperature below a borderline of
an .alpha.-phase and an .alpha.+Cu.sub.3Ti phase.
6. The manufacturing method for a high strength titanium copper
alloy according to claim 4; wherein the alloy is cooled, after
final recrystallization annealing, at a cooling rate of 100.degree.
C./sec or more; cold worked at a working ratio of 5 to 70%; and
subjected to an aging process for 1 hour or more to 15 hours or
less at a temperature of 300.degree. C. or more to 600.degree. C.
or less.
7. The manufacturing method for a high strength titanium copper
alloy according to claim 5; wherein the alloy is cooled, after
final recrystallization annealing, at a cooling rate of 100.degree.
C./sec or more; cold worked at a working ratio of 5 to 70%; and
subjected to an aging process for 1 hour or more to 15 hours or
less at a temperature of 300.degree. C. or more to 600.degree. C.
or less.
8. A terminal connector using a high strength titanium copper alloy
according to claim 1.
9. A terminal connector using a high strength titanium copper alloy
according to claim 2.
10. A high strength titanium copper alloy which is subjected to an
aging process after press working, the alloy consisting of: Ti at
2.0% by mass or more to 3.5% by mass or less; and the balance of
copper and inevitable impurities; the alloy further comprising a
grain size of 5 to 15 .mu.m; and an electrical conductivity of 12.5
to 15.3% IACS; wherein cracking does not occur by a W-bending test
in a transverse direction to a rolling direction with a bending
radius of zero before the aging process, and the hardness of the
worked matrix after the aging process is 310 HV or more.
11. A high strength titanium copper alloy which is subjected to an
aging process after press working, the alloy consisting of: Ti at
2.0% by mass or more to 3.5% by mass or less; at least one of Zn,
Cr, Zr, Fe, Ni, Sn, In, Mn, P, and Si at 0.01% by mass or more to
3.0% by mass or less in total; and the balance of copper and
inevitable impurities; the alloy further comprising a grain size of
5 to 15 .mu.m; wherein cracking does not occur by a W-bending test
in a transverse direction to a rolling direction with a bending
radius of zero before the aging process, and the hardness of the
worked matrix after the aging process is 300 Hv or more.
12. A manufacturing method for a high strength titanium copper
alloy according to claim 10, comprising the steps of: performing
final recrystallization annealing at a temperature below a
borderline of an .alpha.-phase and an .alpha.+Cu.sub.3Ti phase to
adjust the grain size to 5 to 15 .mu.m; and performing final cold
rolling at a working ratio of 5 to 50%.
13. A manufacturing method for a high strength titanium copper
alloy according to claim 11, comprising the steps of: performing
final recrystallization annealing at a temperature below a
borderline of an .alpha.-phase and an .alpha.+Cu.sub.3Ti phase to
adjust the grain size to 5 to 15 .mu.m; and performing final cold
rolling at a working ratio of 5 to 50%.
14. A terminal connector using a high strength titanium copper
alloy according to claim 10.
15. A terminal connector using a high strength titanium copper
alloy according to claim 11.
16. A high strength titanium copper alloy consisting of: Ti at 2.0%
by mass or more to 3.5% by mass or less; Zn at 0.05% by mass or
more to 2.0% by mass or less; at least one of Cr, Zr, Fe, Ni, Sn,
In, Mn, P, and Si at 0.01% by mass or more to 3.0% by mass or less
in total; and the balance of copper and inevitable impurities; the
alloy further comprising a tensile strength of 1200 MPa or more and
an electrical conductivity of 10% IACS or more.
17. A manufacturing method for a high strength titanium copper
alloy according to claim 16, comprising the steps of: hot rolling
at a temperature of 600.degree. C. or more; cold rolling
successively at a working ratio of 95% or more; and aging at a
temperature of 340.degree. C. or more to less than 480.degree. C.
for 1 hour or more to less than 15 hours while maintaining an
agglomerated matrix after the cold rolling.
18. A fork-shaped connector using a high strength titanium copper
alloy according to claim 16.
19. A high strength titanium copper alloy which is subjected to an
aging process after press working, the alloy consisting of: Ti at
2.0% by mass or more to 3.5% by mass or less; Zn at 0.05% by mass
or more to 2.0% by mass or less; at least one of Cr, Zr, Fe, Ni,
Sn, In, Mn, P, and Si at 0.01% by mass or more to 3.0% by mass or
less in total; and the balance of copper and inevitable impurities;
the alloy further comprising a worked matrix having a hardness of
345 Hv or more after the aging process.
20. A manufacturing method for a high strength titanium copper
alloy according to claim 19, comprising the steps of: hot rolling
at a temperature of 600.degree. C. or more; and cold rolling
successively at a working ratio of 95% or more.
21. A fork-shaped connector using a high strength titanium copper
alloy according to claim 19.
Description
[0001] This is a Continuation of application Ser. No. 10/076,433
filed Feb. 19, 2002. The disclosure of the prior application is
hereby incorporated by reference herein in its entirety.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to high strength titanium
copper alloys, which are superior in bending properties, used for
terminal connectors and other electronic components, a
manufacturing method therefor, and a terminal connector using the
same. The invention also relates to high strength titanium copper
alloys, which are optimal for a fork-shaped contact demanding high
strength for raw material of metal material, a manufacturing method
therefor, and a fork-shaped connector using the titanium copper
alloy.
[0004] 2. Description of the Related Art
[0005] Copper alloy containing titanium such as C1990 (hereinafter
called titanium copper alloy) is noted for its superior workability
and mechanical strength, and is widely used in terminal connectors
and in other applications for electronic components. On the other
hand, the trend toward miniaturization of electronic components is
recently stronger than before, and the wrought product of copper
alloys for electronic components are required to be even thinner in
thickness to cope with this trend. In a view of the thinness of
material, higher strength of the material itself is required to
maintain the contact pressure of the connector, and a small bending
radius is required in the bending process of components to fulfil
the function in a limited space. That is, the titanium copper alloy
is required to have contrary characteristics of high electrical
conductivity and high strength and superior bending properties.
[0006] Furthermore, along with the advancement in high density
mountings for cellular phones, digital cameras, video cameras,
etc., metal members for electronic components such as terminal
connectors and lead frames are bent and formed in very complicated
shapes, and an superior bending properties is required, in
particular, in addition to having high strength.
[0007] Under such circumstances, in order to improve bending
properties and the stress relief rate of the titanium copper alloy,
much has been reported about the manufacturing method of solution
treatment of crystals, under heat treatment condition, not
exceeding a grain size of 20 .mu.m (for example, Japanese Patent
Application Laid-Open No. 7-258803). However, to satisfy the
requirement of bending properties of the copper alloy material used
in recent electronic components such as terminal connectors, at
present, such an improved titanium copper alloy does not have
sufficient bending properties. To satisfy the requirements for
titanium copper alloy, it is important to improve the correlation
of strength and bending properties, and for this purpose, it is
also necessary to improve the manufacturing method for titanium
copper alloy.
[0008] Hitherto, where the required tensile strength of copper
alloy for electronic component was at a medium level of about 500
to 800 MPa, brass, phosphor bronze, or nickel silver is used, or
where a higher electrical conductivity is required, Cu--Ni--Si,
Cu--Cr--Zr, or Cu--Cr--Sn copper alloy is used, and where a high
strength over about 900 MPa is required, beryllium copper or
titanium copper is used.
[0009] Recently, demand for FPCs (flexible printed circuit boards)
is increasing, and the connectors for FPCs are modified. The
fork-shaped connector is used in a connector for an FPC, and in
contrast to the general-purpose connector used on the surface
contacting with metal material, it is designed to contact with the
circuit board on the fracture of the copper alloy plate.
Accordingly, a bending process is not necessary, and the
fork-shaped connector is required to have a high strength, in the
first place, if the bending properties are not favorable.
[0010] Specifically, the fork-shaped connector is required to have
a tensile strength of at least 1000 MPa or more, and in order to be
applicable to versatile designs, a tensile strength of 1200 MPa or
more is necessary.
[0011] Stainless steel of high strength, for example, SUS301 has a
tensile strength exceeding 1200 MPa, but stainless steel is low in
electrical conductivity, about 2.4% IACS, and cannot be used for a
fork-shaped connector. A fork-shaped connector is required to have
an electrical conductivity of at least 10% IACS.
[0012] As a copper alloy having a tensile strength of 1200 MPa or
more, beryllium copper is well known. As a high strength copper
alloy, titanium copper is also usable, but in order to have a
tensile strength of 1200 MPa or more, titanium must be contained at
4% by mass, and it further requires special treatment such as MTH
(aging, working, heating) (Lecture on Modern Metal Materials 5,
Nonferrous Materials, p. 78 (Japan Society of Metallurgy),
etc.).
[0013] However, titanium copper containing Ti at 4% by mass is poor
in workability, and is likely to crack in hot rolling or to develop
edge cracks in cold rolling, and it is difficult to manufacture at
high proof stress industrially, and it is also difficult to sell
commercially as material for electronic components. The MTH
treatment is a process of cold rolling of titanium copper after
aging, followed by heat treatment, but cold rolling of titanium
copper alloy after aging is likely to cause edge cracking, and it
is difficult to manufacture.
[0014] On the other hand, in the conventional manufacturing method
for titanium copper containing 3% by mass of Ti (C1990), the
obtained tensile strength is about 1000 MPa at most. Japanese
Patent Application Laid-Open No. 7-258803 discloses a manufacturing
method of solution treatment of titanium copper alloy in the heat
treating condition in which the crystal grain does not exceed 20
.mu.m, and it is known that a material which is superior in bending
properties and is not lowered in strength can be manufactured as
compared with similar conventional materials; however, titanium
copper of high strength is not obtainable. Therefore, as a copper
alloy having a tensile strength of 1200 MPa, there was no copper
alloy other than beryllium copper, which monopolized the
market.
[0015] However, beryllium copper is not an ideal copper alloy; it
is inferior to titanium copper in stress relief characteristics,
and is not fully satisfactory. Therefore, in a titanium copper
alloy containing Ti at 2.0 to 3.5% by mass, if the tensile strength
could be improved to 1200 MPa or more, the alloy would be an
optimal high strength copper alloy having the stress relief
characteristics, and hence improvement is anticipated.
SUMMARY OF THE INVENTION
[0016] The invention is made in light of above circumstances, and
it is hence an object thereof to provide a titanium copper alloy as
a terminal connector material which is enhanced in strength without
having lowered bending properties. It is also an object of the
invention to provide a high strength titanium copper alloy having a
tensile strength of 1200 MPa or more, equivalent to that of
beryllium copper, and an electrical conductivity of 10% IACS or
more, a manufacturing method thereof, and an electronic component
using the same high strength titanium copper alloy, in particular,
a fork-shaped connector.
[0017] The inventors attempted to adjust conditions of the final
recrystallization annealing of titanium copper alloy (conditions of
solution treatment), and the subsequent cold rolling and aging
conditions, researched the relationship between characteristic
values after final heat treatment, and discovered that a titanium
copper alloy material enhanced in strength without having lowered
bending properties can be obtained stably.
[0018] The present invention is made on the basis of the above
knowledge. A first aspect of the present invention provides a high
strength titanium copper alloy consisting of Ti at 2.0% by mass or
more to 3.5% by mass or less; the balance of copper and inevitable
impurities; and an average grain size of 20 .mu.m or less; the
alloy further comprising a 0.2% proof stress expressed by "b" of
800 N/mm.sup.2 or more; and a bending radius ratio (bending
radius/sheet thickness) not causing cracking as expressed by "a" by
a W-bending test in a transverse direction to a rolling
direction;
wherein "a" and "b" satisfy a.ltoreq.0.05.times.b-40.
[0019] The second aspect of the invention provides a high strength
titanium copper alloy consisting of Ti at 2.0% by mass or more to
3.5% by mass or less; at least one of Zn, Cr, Zr, Fe, Ni, Sn, In,
Mn, P, and Si at 0.01% by mass or more to 3.0% by mass or less in
total; and the balance of copper and inevitable impurities; the
alloy further comprising an average grain size of 20 .mu.m or less;
a 0.2% proof stress expressed by "b" of 800 N/mm.sup.2 or more; and
a bending radius ratio (bending radius/sheet thickness) not causing
cracking as expressed by "a" by a W-bending test in a transverse
direction to a rolling direction; wherein "a" and "b" satisfy
a.ltoreq.0.05.times.b-40.
[0020] The reasons for setting the numerical values specified above
are explained below together with the operation of the invention.
In the following explanation, "%" means "% by mass."
A. Ti: 2.0 to 3.5%
[0021] Ti is characterized by inducing spinodal decomposition by
aging of Cu--Ti alloy, thereby generating a concentration
modulation structure in the matrix, and assuring a very high
strength. However, desired reinforcement is not expected if the
content is less than 2.0%. If Ti is contained at more than 3.5%,
precipitation of grain boundary reaction type is likely to occur,
and the strength may be lowered, in contrast, and the workability
deteriorates. Hence, the content of Ti is defined in a range of 2.0
to 3.5%.
B. Zn, Cr, Zr, Fe, Ni, Sn, In, Mn, P, Si: 0.01 to 3.0% in Total
[0022] Cr, Zr, Fe, Ni, Sn, In, Mn, P, and Si are all known to
suppress precipitation of grain boundary reaction type without
substantially lowering the electrical conductivity of a Cu--Ti
alloy, make grain size fine, and increase the strength by aging
precipitation. Moreover, Sn, In, Mn, P, and Si are known to
increase the strength of a Cu--Ti alloy by solid solution
reinforcement. Therefore, one or more elements thereof are added as
required. However, if the total content thereof is less than 0.01%,
desired effects are not expected. If the total content exceeds
3.0%, the electrical conductivity and workability of the Cu--Ti
alloy deteriorate significantly. Therefore, the content of one
element or more elements of Zn, Cr, Zr, Fe, Ni, Sn, In, Mn, P, and
Si is specified to be in a range of 0.01 to 3.0% in total.
[0023] Of these additive elements, Zn is expected to suppress heat
peel off of solder without lowering the electrical conductivity of
a Cu--Ti alloy, and is added most preferably. However, if the
content of Zn is less than 0.05%, desired effects are not expected.
If the content of Zn exceeds 2.0%, the electrical conductivity and
stress relief characteristics deteriorate. Therefore, the content
of Zn is preferred to be in a range of 0.05 to 2.0%.
C. Characteristics of Titanium Copper Alloy
[0024] In order that a titanium copper alloy be used as a terminal
connector material, in particular, the bending properties are
important because it is used being formed into a complicated part,
together with its material strength. In the designing of a part,
considerations are given to the 0.2% proof stress as the index of
material strength, and the bending properties evaluated by the
state of the bending part when it is bent at various bending radii
with respect to the material plate thickness. The inventors
quantitatively analyzed the bending properties depending on the
strength and plate thickness required in the recent electronic
components, and discovered a specific scale balancing both as
explained below.
[0025] That is, when the 0.2% proof stress expressed by "b" is 800
N/mm.sup.2 or more, the bending radius ratio (bending radius/sheet
thickness) not causing cracking as expressed by "a" by a W-bending
test in a transverse direction to a rolling direction, "a" and "b"
satisfy a.ltoreq.0.05.times.b-40, the high strength and bending
properties can be balanced, and the titanium copper alloy can meet
recent demands. The 0.2% proof stress of titanium copper alloy is
defined to be 800 N/mm.sup.2 or more because the high strength
characteristics as a titanium copper alloy cannot be exhibited
sufficiently if less than 800 N/mm.sup.2. In the invention, the
grain size is measured by using the value obtained by the cutting
method according to JIS H 0501.
[0026] To enhance the strength of titanium copper alloy, it has
been known to reinforce the solid solution by adding alloy
elements, reinforce precipitation by adequately controlling the
aging temperature, or reinforce by work hardening by adequately
controlling the working ratio before aging, and hitherto the
desired material characteristics were assured by combining these
methods. However, when the strength is enhanced by such reinforcing
mechanisms only, the bending properties may deteriorate, and it may
fail to reach a desired region of material characteristics.
Accordingly, the inventors conducted various tests, and found that
there is a relationship between the strength and bending properties
with respect to the grain size, and that the average grain size of
20 .mu.m is required in order to obtain the above relationship of
0.2% proof stress and bending radius ratio.
[0027] Furthermore, in order to enhance the bending properties
without lowering the material strength, it is necessary to define
the grain size strictly, and to control adequately the final
recrystallization annealing condition, cold working ratio, and
aging temperature. The invention also provides a terminal connector
using such titanium copper alloy.
[0028] The manufacturing method for titanium copper alloy of the
invention is characterized by performing final recrystallization
annealing at a temperature below the borderline L of the
.alpha.-phase and the .alpha.+Cu.sub.3Ti phase shown in FIG. 1.
[0029] It is essential in the invention to specify the final
recrystallization annealing condition, and the subsequent cold
working and aging conditions. The final recrystallization annealing
condition is intended to facilitate the subsequent process, and to
adjust the material characteristics and grain size.
[0030] Hitherto, to manufacture a titanium copper alloy of which
the grain size does not exceed 20 .mu.m, the grain size was
adjusted by adequately controlling the treatment time by
determining the treating temperature in a solid solution region of
Ti. However, in the case of recrystallization by solution treatment
at high temperature and in a short time, since the uniformity of
grain size is insufficient, although the strength may be enhanced,
the workability is impaired, the characteristics vary widely, and
hence it was difficult to stabilize the high strength of titanium
copper alloy at a grain size of 20 .mu.m or less.
[0031] Accordingly, the inventors made various tests about
recrystallization annealing, and discovered that a titanium copper
alloy superior in bending properties without lowering the strength
and having small variations of characteristics can be obtained, in
each composition, by performing recrystallization annealing at a
temperature below the borderline L of .alpha.-(.alpha.+Cu.sub.3Ti)
which is the borderline of the solid solution-precipitation, that
is, in a temperature region partially causing precipitation,
instead of temperature region of solid solution of all contained Ti
in Cu, for a time so that the average grain size does not exceed 20
.mu.m. The temperature y (.degree. C.) of
.alpha.-(.alpha.+Cu.sub.3Ti) borderline L can be approximated in
formula y=50x+650, where x (%) is the concentration of Ti.
[0032] Meanwhile, as the grain size becomes finer, the bending
properties are better, but if the average grain size is less than 3
.mu.m, non-recrystallized portion may remain, and the bending
properties may deteriorate, and therefore the average grain size
should be 20 .mu.m or less, more preferably 3 to 20 .mu.m.
[0033] The cooling rate after recrystallization annealing should be
100.degree. C./sec or more. If the cooling rate is less than
100.degree. C./sec, spinodal decomposition occurs at the time of
cooling, and the material is hardened, and the subsequent working
becomes difficult. It is hence preferred to cool the material
surface coming out of the heating furnace by water or steam and
water, so that the material can be cooled uniformly while
maintaining the specified cooling rate.
[0034] Furthermore, in order to obtain such characteristics
correlation of 0.2% proof stress and bending properties, aside from
the recrystallization annealing condition, it is required to
specify the subsequent cold working ratio and aging condition
strictly. After recrystallization annealing, almost all Ti of the
material is in solid solution, and then it is worked by cold
rolling and aged. The working ratio of cold rolling is preferred to
be 5 to 70% or less. If it is less than 5%, increase in strength by
work hardening is small, and desired strength is not obtained, but
when the working ratio exceeds 70%, although a high strength is
obtained by adequately controlling the aging condition, the bending
properties deteriorate, and the correlation of 0.2% proof stress
and bending properties are not obtained.
[0035] The aging condition is preferred to be 300.degree. C. or
more to 600.degree. C. or less. If the aging temperature is less
than 300.degree. C., aging is not sufficient, and the material
strength is not improved. If it is aged at a temperature over
600.degree. C., the solid solution amount of Ti is excessive (the
precipitation amount is less), and desired strength is not
obtained. The period of aging is preferred to be 1 hour or more to
15 hours or less. If it is less than 1 hour, improvement of
strength and electrical conductivity by aging is not expected, or
if it exceeds 15 hours, the strength declines due to
over-aging.
[0036] Accordingly, the titanium copper alloy of the invention is
an aging-cured type copper alloy of superior bending properties and
high strength, and it is used in the terminal connector of small
size in which superior bending properties and high strength are
required. If the contact of the terminal connector is plated before
or after press working, the strength and bending properties hardly
deteriorate, and the effect of the invention is exhibited.
[0037] Such high strength titanium is generally press worked after
the aging process. The inventors discovered that the bending
properties are further enhanced by limiting the range of grain size
in further narrower bounds while aging after pressing process. That
is, the invention according to a third aspect provides a titanium
copper alloy which is subjected to an aging process after press
working, the alloy consisting of: Ti at 2.0% by mass or more to
3.5% by mass or less; and the balance of copper and inevitable
impurities; the alloy further comprising a grain size of 5 to 15
.mu.m; wherein cracking does not occur by a W-bending test in a
transverse direction to a rolling direction with a bending radius
of zero before the aging process, and the hardness of the worked
matrix after the aging process is 300 Hv or more, and it is more
preferable that it be 310 Hv or more.
[0038] Moreover, the invention according to a fourth aspect
provides a titanium copper alloy which is subjected to an aging
process after press working, the alloy consisting of: Ti at 2.0% by
mass or more to 3.5% by mass or less; at least one of Zn, Cr, Zr,
Fe, Ni, Sn, In, Mn, P, and Si at 0.01% by mass or more to 3.0% by
mass or less in total; and the balance of copper and inevitable
impurities; the alloy further comprising a grain size of 5 to 15
.mu.m; wherein cracking does not occur by a W-bending test in a
transverse direction to a rolling direction with a bending radius
of zero before the aging process, and the hardness of the worked
matrix after the aging process is 300 Hv or more, and it is more
preferable that it be 310 Hv or more.
[0039] Such high strength titanium copper alloy is manufactured by
performing final recrystallization annealing at a temperature below
the borderline of .alpha.-phase and .alpha.+Cu.sub.3Ti phase to
adjust the grain size to 5 to 15 .mu.m, and executing final cold
rolling at a working ratio of 5 to 50%. The aging conditions may be
the same as in the first and second aspects of the invention, and
such a manufacturing method is also one of the features of the
invention. Furthermore, the third and fourth aspects are also
applied in the terminal connector of small size where superior
bending properties and high strength are required, and such a
terminal connector is also one of the features of the
invention.
[0040] The inventors further researched the manufacturing process
of titanium copper alloy, and adjusted the hot rolling condition,
and the subsequent cold rolling condition and aging condition, and
discovered that a high strength titanium copper alloy having a
tensile strength of 1200 MPa or more can be obtained stably.
[0041] That is, a fifth aspect of the invention provides a high
strength titanium copper alloy consisting of: Ti at 2.0% by mass or
more to 3.5% by mass or less; and the balance of copper and
inevitable impurities;
the alloy further comprising a tensile strength of 1200 MPa or more
and an electrical conductivity of 10% IACS or more.
[0042] The sixth aspect of the invention provides a high strength
titanium copper alloy consisting of: Ti at 2.0% by mass or more to
3.5% by mass or less; Zn at 0.05% by mass or more to 2.0% by mass
or less; at least one of Cr, Zr, Fe, Ni, Sn, In, Mn, P, and Si at
0.01% by mass or more to 3.0% by mass or less in total; and the
balance of copper and inevitable impurities;
the alloy further comprising a tensile strength of 1200 MPa or more
and an electrical conductivity of 10% IACS or more.
[0043] The high strength titanium copper alloy can be manufactured
by hot rolling at a temperature of 600.degree. C. or more, cold
rolling successively at a working ratio of 95% or more, and aging
at temperature of 340.degree. C. or more to less than 480.degree.
C. for 1 hour or more to less than 15 hours while maintaining the
state of the matrix after cold rolling.
[0044] The invention further provides a fork-shaped connector using
the high strength titanium copper alloy of the fifth or sixth
aspect.
[0045] In the fifth and sixth aspects, the reasons for limiting the
contents are the same as in the first and second aspects. The
reasons for limiting the characteristic values in the fifth and
sixth aspects are as follows.
(1) Tensile Strength
[0046] The fork-shaped connector for FPC differs from the
general-purpose connector contacting with the surface of metal
material, is designed to contact with the circuit board at the
fracture of copper alloy plate, and is not processed by bending.
Accordingly, the requirement of prime importance is the strength.
In the invention, the strength is evaluated by tensile strength.
The required tensile strength of a fork-shaped connector is not
sufficient at the tensile strength obtained by general-purpose
copper alloy such as brass, phosphor bronze, or nickel silver, but
is 1200 MPa or more so as to be applicable to versatile designs as
fork-shaped connectors.
(2) Electrical Conductivity
[0047] As the metal material for fork-shaped connector for FPC, the
strength is most important, but since the fork-shaped connector is
designed to contact at the fracture of metal material, the contact
resistance is larger than in other connectors. As a countermeasure,
the contact area is plated with gold, but certain electrical
conductivity is also required as metal material. Some stainless
steel materials are high in strength, but the electrical
conductivity is low, and the heat generated in the contact portion
is poorly dissipated. At least, an electrical conductivity of 10%
IACS is needed.
[0048] The high strength titanium copper alloy of the fifth and
sixth aspects is manufactured in the following method.
[0049] Hitherto, in the manufacturing method for enhancing the
strength of titanium copper alloy, after hot rolling, cold rolling
and heat treatment, the material is heated (solution treatment) to
adjust the grain size at 20 .mu.m or less, and the working ratio of
final cold rolling and aging temperature are properly controlled,
so that a material of tensile strength of about 1000 MPa and
superior bending property is manufactured (Japanese Patent
Application Laid-Open No. 7-258803). However, considering the
manufacturing efficiency, in the Ti amount range of 2.0 to 3.5% by
mass, the tensile strength of 1200 MPa or more is not yet achieved
in the high strength titanium copper alloy manufactured in this
method. As for the MTH treatment mentioned above, the tensile
strength of 1200 MPa or more is not yet obtained in the Ti amount
range of 2.0 to 3.5% by mass.
[0050] In the manufacturing method of the invention, it is
essential to specify the "material temperature in hot rolling,"
"working ratio in cold rolling before aging process," and "aging
condition."
(1) Hot Rolling
[0051] Hot rolling is intended to homogenize the cast matrix, and
to induce dynamic recrystallization by rolling at higher
temperature, so that subsequent processes can be easily performed.
If the material temperature is lower than 600.degree. C. during hot
rolling, titanium copper alloy causes spinodal decomposition to
harden abruptly, and the subsequent cold working is difficult, and
the characteristics vary widely. Therefore, the material
temperature is kept above 600.degree. C. during the hot rolling
process. As for cooling after hot rolling, the material hardness
unless cooled quickly and the subsequent rolling is difficult, and
therefore, by water cooling or the like, the cooling rate of the
material is preferred to be 200.degree. C./sec or more.
(2) Cold Rolling
[0052] So far, the titanium copper alloy was cold rolled and
annealed after the hot rolling process, and then cold rolled to a
specified sheet thickness, and was further heated (solution
treatment) for a short time at a high temperature before aging
process. That is, heat treatment is intended to adjust the material
characteristics and to make the subsequent processing easier, but
since the heat treatment is applied between the hot rolling and the
aging, a proper working ratio of cold rolling cannot be set, the
strength is lowered, and it is hard to obtain a desired high
strength.
[0053] However, by strictly specifying the working condition of hot
rolling, a strong working of 95% or more is possible in the
subsequent cold rolling. Herein, the working ratio of cold rolling
is 95% or more because the working ratio must be specified strictly
in order to obtain a tensile strength of 1200 MPa or more by the
subsequent aging process, although the strength is generally
elevated as the working ratio is higher, and a tensile strength of
1200 MPa or more can be obtained by defining the working ratio at
95% or more.
(3) Aging
[0054] After the cold rolling process, the material is aged in
order to reinforce the strength and improve the elongation, elastic
property and electrical conductivity. The aging temperature is
defined in a range of 340.degree. C. to less than 480.degree. C.,
that is, if the aging temperature is less than 340.degree. C., the
aging effect is not sufficient, and the strength and electrical
conductivity are not improved, but at 480.degree. C. or more, since
the cold rolling working ratio before aging process is strong
working of 95% or more, it may result in over-aging if aged for a
short time, and the strength is lowered and desired characteristics
are not obtained, and therefore the temperature range of
340.degree. C. or more to less than 480.degree. C. is
specified.
[0055] The aging period is 1 hour or more to less than 15 hours,
that is, if less than 1 hour, improvement of strength and
electrical conductivity by aging is not expected, and if 15 hours
or more, the strength is lowered due to excessive over-aging, and
hence the aging period is defined in a range of 1 hour or more to
less than 15 hours.
[0056] Such high strength titanium copper is generally press worked
after the aging process. The inventors discovered that dimensional
changes after aging are substantially small. Therefore, the
invention according to a seventh aspect provides to a titanium
copper alloy which is subjected to an aging process after press
working, the alloy consisting of: Ti at 2.0% by mass or more to
3.5% by mass or less; and the balance of copper and inevitable
impurities; the alloy further comprising a worked matrix having a
hardness of 345 Hv or more after the aging process.
[0057] Furthermore, an eighth aspect of the invention provides a
titanium copper alloy which is subjected to an aging process after
press working, the alloy consisting of: Ti at 2.0% by mass or more
to 3.5% by mass or less; Zn at 0.05% by mass or more to 2.0% by
mass or less; at least one of Cr, Zr, Fe, Ni, Sn, In, Mn, P, and Si
at 0.01% by mass or more to 3.0% by mass or less in total; and the
balance of copper and inevitable impurities;
the alloy further comprising a worked matrix having a hardness of
345 Hv or more after the aging process.
[0058] The high strength titanium copper alloys of the seventh and
eighth aspects are manufactured by hot rolling at a temperature of
600.degree. C. or more, and cold rolling successively at a working
ratio of 95% or more, and such a manufacturing method is also one
of the features of the invention. The high strength titanium copper
alloys of the seventh and eighth aspects are particularly suited to
a fork-shaped connector, and such a fork-shaped connector is also
one of the features of the invention.
BRIEF DESCRIPTION OF DRAWING
[0059] FIG. 1 is a Ti--Cu equilibrium diagram.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Examples
Example 1
[0060] The invention is specifically explained below by referring
to example 1 which shows a particularly preferred alloy composition
range. First, using electrolytic cathode copper or oxygen-free
copper as a raw material, copper alloy ingots (50 mm
thick.times.100 mm wide.times.200 mm long) of various compositions
shown in Table 1 (examples) and Table 2 (comparative examples) were
melted in a high frequency melting furnace. Consequently, each
ingot was heated for 1 hour at a temperature of 850 to 950.degree.
C., and was hot rolled, and a plate with 8 mm thick was obtained.
At this time, the material temperature after hot rolling was
650.degree. C. or more, and the material was cooled in water after
hot rolling. The oxide layer on the surface of the sheet was
polished and removed, and rolling and recrystallization annealing
were repeated, and after proper pickling, recrystallization
annealing (solution treatment) was conducted in the condition of
Tables 1 and 2, being followed by cold rolling and aging, and a
material having a thickness of 0.2 mm was obtained. After
recrystallization annealing, the material was cooled by immersing
in water after heat treatment. At this time, the cooling rate was
200.degree. C./sec or more, which was confirmed by attaching a
thermocouple to the material surface. The table also records the
value of temperature of .alpha.-(.alpha.+Cu.sub.3Ti) borderline as
approximated in formula (y=50x+650). As shown in Table 1, in the
invention, recrystallization annealing was conducted at a
temperature below the .alpha.-(.alpha.+Cu3Ti) borderline and within
50.degree. C.
TABLE-US-00001 TABLE 1 Manufacturing conditions Recrystallization
annealing condition Aging condition Composition Temperature at
Average crystal Cold rolling Heating (unit: % by mass) .alpha. -
(.alpha. + Cu.sub.3Ti) Temperature particle size processing
temperature Holding time No. Ti Others borderline (.degree. C.)
(.degree. C.) (.mu.m) ratio (%) (.degree. C.) (hours) 1 3.2 -- 810
770 10 50 380 6 2 2.9 -- 795 750 5 40 400 6 3 2.6 -- 780 750 5 40
420 6 4 2.4 -- 770 750 5 40 420 6 5 3.5 -- 825 770 10 50 400 6 6
3.0 -- 800 770 10 50 400 6 7 2.9 Zn1.0 795 750 10 50 380 10 8 2.2
Sn0.21 760 750 10 30 380 10 9 2.5 Cr0.10 775 750 10 65 380 6 10 3.0
Zr0.15 800 770 10 60 380 6 11 3.2 Fe0.20 810 750 5 50 400 6 12 2.7
Ni0.30 785 750 10 50 380 6 13 3.2 In0.25 810 770 5 40 420 6 14 3.0
Mn0.10 800 750 10 50 380 10 15 3.1 P0.07 805 750 5 50 400 10 16 2.8
Si0.13 790 750 10 30 380 6 17 2.7 Zn0.70, Cr0.30, 785 750 5 60 380
6 Zr0.15 18 2.7 Zn0.50, Fe0.15, 785 750 10 60 420 6 P0.05 19 2.9
Zn1.2, In0.10, 795 750 5 30 420 6 Fe0.16, P0.03 20 3.1 Sn0.15,
P0.15 805 770 10 50 400 6 21 2.6 Mn0.15, P0.10 780 750 10 60 380 6
22 2.9 Zn0.80, Ni0.25, 795 750 10 60 380 6 Si0.05 23 3.3 Zn1.1,
Cr0.15, 815 770 10 60 380 6 Zr0.05, Mn0.05 24 3.2 Zn0.1, Ni0.25,
810 770 10 60 380 6 Sn0.15
TABLE-US-00002 TABLE 2 Manufacturing conditions Recrystallization
annealing condition Aging condition Composition Temperature at
Average crystal Cold rolling Heating (unit: % by mass) .alpha. -
(.alpha. + Cu.sub.3Ti) Temperature particle size processing
temperature Holding time No. Ti Others borderline (.degree. C.)
(.degree. C.) (.mu.m) ratio (%) (.degree. C.) (hours) 25 1.0 -- 700
680 5 50 400 6 26 1.7 -- 735 700 5 50 380 6 27 5.5 Ni0.50, P0.15
925 770 10 40 450 6 28 4.5 Zn0.50, Ni1.20, 875 770 10 40 400 6
Sn0.50 29 2.8 Zn4.2, Ni1.30, 790 750 10 40 380 6 Si0.40 30 3.1
Zn1.5, Ni1.50, 805 750 5 50 380 10 Sn1.10, P0.30 31 3.0 -- 800 810
25 50 380 6 32 2.9 -- 795 850 30 60 380 6 33 3.2 -- 810 750 10 80
360 2 34 2.7 Zn1.0, In0.30, 785 750 10 90 360 2 P0.15 35 3.1 Zn1.5,
Fe0.35, 805 750 5 60 200 6 Mn0.15 36 3.1 Zn1.8, Sn0.50 805 750 10
50 450 50 37 3.0 -- 800 770 10 50 650 0.5 38 2.9 -- 795 750 10 40
450 0.5 39 2.8 -- 790 750 5 50 200 50
[0061] From these materials obtained by such series of processing,
various test pieces were sampled, and the characteristics thereof
were tested. First, to evaluate the elastic properties and
strength, tensile tests were conducted, and 0.2% proof stress,
tensile strength and elongation were measured according to JIS Z
2201 and Z 2241. As for bending properties, test pieces measuring
10 mm wide.times.100 mm long were sampled at the transverse angle
to the rolling direction, and W-bending tests (JIS H 3110) were
conducted at various bending radii, and the minimum bending radius
ratio (r/t, r: bending radius, t: test piece thickness (sheet
thickness)), not causing cracking, capable of obtaining a favorable
bend appearance of rank C or higher in the evaluation standard
according to Japan Brass Technical Association standard JBTA T307:
1999 was determined by observing the bend with an optical
microscope. This evaluation standard is classified in five ranks;
rank A: no wrinkle, rank B: small wrinkle, rank C: large wrinkle,
rank D: small crack, and rank E: large crack, and in the case of
bending test at larger bending radius ratio than the bending radius
ratio for obtaining the result of rank C, appearance of the same or
better ranks A to C is obtained. In W-bending test, the bending
axis is parallel (Bad Way) to the rolling direction in which the
bending properties are inferior. The bending radius is the distance
from the center of bending to the inner circumference of the test
piece, and the results were evaluated by using a tool having
various bending radii.
[0062] Results of characteristic tests are shown in Table 3
(examples) and Table 4 (comparative examples). In examples No. 1 to
No. 24, the bending radius ratio (bending radius/sheet thickness)
not causing crack as expressed by "a" and 0.2% proof stress
expressed by "b", and "a" and "b" satisfy the relationship
"a.ltoreq.0.05.times.b-40", and the titanium copper alloy
(evaluation: favorable) meeting the recent demands, and
well-balanced between high strength and bending properties, could
be obtained. In contrast, in comparative examples No. 25 to No. 39,
as explained below, the requirements of the invention were not
satisfied, and poor bending properties and other problems were
found at 0.2% proof stress.
[0063] In No. 25 and 26, since the Ti content is low, high strength
of 0.2% proof stress of 800 N/mm.sup.2 or more is not obtained. In
No. 27 and 28, the strength is lower than in the alloy of the
example of the invention, and the bending radius ratio is large,
and the bending properties are poor. This is because the Ti content
is too high, and there is too much precipitation into the grain
boundary not contributing to enhancement of strength, and it seems
cracks are initiated from the precipitates in the grain boundary at
the time of performing tension tests and bending tests.
[0064] No. 29 has too high amount of Zn, and No. 30 has too high a
total amount of subsidiary additives, and they are both low in
electrical conductivity and poor in bending properties. No. 31 and
32 are examples of extremely high recrystallization temperature, in
which average grain size of 20 .mu.m or less was not obtained, and
high 0.2% proof stress could not be obtained. When compared with an
alloy example of 0.2% proof stress of the same level in the
invention, the bending radius ratio is large and bending properties
are poor. No. 31 is a mixed grain matrix. Accordingly, the average
grain size in No. 31 is 25 .mu.m, being smaller than in No. 32, but
the bending radius ratio varied in a range of 3.0 to 5.0. The
maximum value is recorded in Table 4.
[0065] No. 33 and 34 are examples of too high working ratio of cold
rolling, but by shortening the aging period, a high 0.2% proof
stress was obtained, however, the bending properties were poor. No.
35 is an example of low aging temperature, and since the
temperature is low, the aging effect is insufficient, and the
strength is low. No. 36 is an example of too long aging period, and
0.2% proof stress is lowered due to over-aging.
[0066] No. 37 is an example of too high aging temperature and too
short aging period, and since the aging temperature is too high,
the solid solution amount of Ti is excessive, and since the aging
period is short, sufficient 0.2% proof stress is not obtained. No.
38 is an example of short aging period, and the aging effect is
insufficient, and the 0.2% proof stress is low. No. 39 is an
example of low aging temperature, and in spite of long aging period
of 50 hours, high 0.2% proof stress is not obtained.
[0067] Therefore, in the alloy examples of the invention, by
recrystallization annealing (solution treatment) at a temperature
below the .alpha.-(.alpha.+Cu.sub.3Ti) borderline in an appropriate
composition, and performing the subsequent cold rolling and aging
process in adequate conditions, a favorable relation of 0.2% proof
stress and bending radius ratio is obtained, and titanium copper
alloy of high strength is obtained without sacrificing the bending
properties. In contrast, in alloys of comparative examples, as
compared with alloys of the invention, favorable relation of 0.2%
proof stress and bending radius ratio is not obtained, and material
with good balance is not produced.
TABLE-US-00003 TABLE 3 0.2% proof Electrical Tensile strength
stress (b) Elongation Bending radius ratio Conductivity No.
(N/mm.sup.2) (N/mm.sup.2) (%) 0.05 .times. b-40 (r/t) (% IACS) 1
1050 900 15 5.0 3.0 14.4 2 1030 880 17 4.0 2.0 14.3 3 1030 900 15
5.0 2.0 14.1 4 1020 900 16 5.0 2.0 14.3 5 1050 940 15 7.0 3.0 13.6
6 1070 960 14 8.0 3.0 13.2 7 1030 890 17 4.5 3.0 14.2 8 880 830 23
1.5 1.0 15.3 9 970 880 18 4.0 3.0 13.4 10 1010 900 17 5.0 3.0 14.4
11 1060 920 17 6.0 3.0 14.5 12 1030 910 15 5.5 3.0 14.5 13 1070 930
10 6.5 4.0 13.4 14 1040 910 15 5.5 3.0 13.4 15 1040 920 14 6.0 3.0
13.7 16 950 850 20 2.5 0.0 13.5 17 1110 950 8 7.5 4.0 14.7 18 1010
900 14 5.0 3.0 14.0 19 970 860 18 3.0 1.0 15.1 20 1060 940 10 7.0
3.0 14.0 21 990 900 12 5.0 4.0 14.4 22 1050 930 11 6.5 3.0 13.7 23
1080 990 8 9.5 4.0 14.7 24 1040 930 11 6.5 4.0 14.6
TABLE-US-00004 TABLE 4 Tensile 0.2% proof Bending radius Electrical
strength stress (b) Elongation ratio Conductivity No. (N/mm.sup.2)
(N/mm.sup.2) (%) 0.05 .times. b-40 (r/t) (% IACS) 25 680 600 11 --
5.0 35.0 26 790 710 8 -- 5.0 20.3 27 750 720 1 -- 8.0 10.4 28 800
750 2 -- 7.0 10.3 29 960 860 8 3.0 5.0 8.3 30 950 840 10 2.0 5.0
7.1 31 850 760 25 -- 5.0 14.3 32 880 800 20 0.0 4.0 14.4 33 1150
970 10 8.5 >10.0 15.3 34 1180 990 15 9.5 >10.0 15.1 35 820
750 3 -- 3.0 12.1 36 890 780 20 -- 3.0 15.2 37 800 720 18 -- 1.0
15.1 38 850 760 7 -- 4.0 12.3 39 820 750 7 -- 3.0 12.4
Example 2
[0068] Test pieces were press worked at the process conducted up to
cold rolling in the same condition as in examples No. 2 and No. 10
in example 1 except that the final recrystallization annealing was
conducted in the conditions as shown in Table 5. The press worked
test pieces were evaluated by W-bending test in the same condition
as in example 1, and then were subjected to aging. The aging
conditions were 400.degree. C. and 6 hours in No. 2, and
380.degree. C. and 6 hours in No. 10. Before and after the aging
process, characteristics of test pieces were examined using the
same method as in example 1, and the results are shown in Table 5.
As is clear from Table 5, when the average grain size is in a range
of 5 to 15 .mu.m, the bending radius ratio (r/t) is zero, and an
extremely superior bending properties were confirmed. In these test
pieces, the hardness after aging process was 310 Hv or more, and
the tensile strength was 1000 MPa or more.
TABLE-US-00005 TABLE 5 Re- crystallization annealing Characteristic
before aging process Characteristics after aging process condition
Average Electrical 0.2% Electrical Holding crystal Tensile Elon-
Con- Tensile proof Elon- Con- Hard- Composition time particle
strength gation ductivity strength stress gation ductivity ness No.
wt % .degree. C. sec. .mu.m MPa % % IACS MBR/t MPa MPa % % IACS Hv
Evaluation 1 2.9Ti--Cu 750 30 3 850 1 3 2 970 900 10 13.7 300
Bending inferior 2 2.9Ti--Cu 750 45 5 790 2 4 0 1030 880 17 14.3
315 Superior 3 2.9Ti--Cu 750 60 8 785 2 4 0 1035 946 12 12.5 320
Superior 4 2.9Ti--Cu 750 80 10 770 2 4 0 1030 920 13 13.7 310
Superior 5 2.9Ti--Cu 750 120 15 760 1 4 0 1020 920 13 14.1 315
Superior 6 2.9Ti--Cu 750 180 20 670 1 5 2 972 854 14 9.5 310
Bending inferior 7 3.0Ti-0.15Zr--Cu 770 20 3 820 1 2 2 980 870 10
13.7 300 Bending inferior 8 3.0Ti-0.15Zr--Cu 770 40 5 780 2 3 0
1015 920 15 14.2 310 Superior 9 3.0Ti-0.15Zr--Cu 770 60 8 770 2 3 0
1020 940 15 13.9 315 Superior 10 3.0Ti-0.15Zr--Cu 770 80 10 780 2 3
0 1010 900 17 14.4 310 Superior 11 3.0Ti-0.15Zr--Cu 770 120 15 760
1 3 0 1015 900 15 14.0 310 Superior 12 3.0Ti-0.15Zr--Cu 770 150 20
690 1 4 2 990 890 17 9.8 300 Bending inferior
Example 3
[0069] Electrolytic cathode copper or oxygen-free copper, and metal
lump of additive elements or master alloy were used as raw
materials, and copper alloy ingots of various compositions shown in
Table 6 (examples) and Table 7 (comparative examples) were melted
in a high frequency melting furnace. Hot tops of these ingots
(measuring 50 mm thick.times.100 mm wide x150 mm long, weighing
about 7000 g) were cut off, and after removing the surface layer,
they were heated for 1 hour or more at 850.degree. C., and the
material was hot rolled to a thickness of 8 mm while keeping the
temperature at 600.degree. C. or more, and it was cooled in water.
The material temperature in hot rolling was measured by two-color
pyrometer preliminarily compensated for temperature. The surface
oxide scale was removed by machine polishing in a thickness of
about 0.4 mm on one side, and the plate was cold rolled to a
specified thickness of less than 0.4 mm (working ratio 95% or
more), and the material surface was degreased by an organic solvent
such as acetone, and specified aging was processed in a vacuum
annealing furnace, and the sample materials were thereby
prepared.
TABLE-US-00006 TABLE 6 Composition and manufacturing conditions of
high strength titanium copper alloys of the invention Manufacturing
conditions Hot rolling condition Cold Min. material Final rolling
Aging process Composition (wt %) temperature thickness processing
Temperature Holding time No. Ti Others (.degree. C.) (mm) ratio (%)
(.degree. C.) (hr) 1 2.3 -- 680 8.0 97 380 6 2 2.6 -- 700 8.0 98
380 6 3 2.9 -- 730 8.5 97 380 10 4 3.2 -- 700 8.0 97 380 10 5 3.4
-- 710 7.5 97 360 6 6 3.5 -- 730 8.0 97 360 6 7 2.9 Zn1.0, Fe0.20
700 8.0 97 400 6 8 2.6 Sn0.21 700 8.5 98 380 6 9 2.5 Cr0.10 710 7.5
96 420 6 10 3.0 Zr0.15 700 7.5 97 380 10 11 3.2 Fe0.20 720 8.0 97
360 8 12 2.7 Ni0.30 700 8.0 97 380 6 13 3.2 In0.25 680 8.0 97 380 6
14 3.0 Mn0.10 700 8.5 96 380 6 15 3.1 P0.07 700 8.5 98 360 8 16 2.8
Si0.13 710 8.0 97 420 6 17 2.7 Zn0.7, Cr0.30, 710 8.0 97 400 6
Zr0.15 18 2.9 Zn1.2, In0.10, 730 8.0 97 380 6 Fe0.16, P0.03 19 3.1
Sn0.15, P0.15 720 7.5 96 420 6 20 2.6 Mn0.15, P0.10 700 7.5 99 360
4 21 2.9 Zn0.8, Ni0.25, 740 8.0 97 360 8 Si0.05 22 3.3 Zn1.1,
Cr0.15, 750 8.0 97 380 10 Zr0.05, Mn0.05 23 3.2 Zn0.1, Ni0.25, 710
8.0 97 380 6 Sn0.15
TABLE-US-00007 TABLE 7 Composition and manufacturing conditions of
alloys of comparative examples Manufacturing conditions Hot rolling
condition Cold Min. material Final rolling Aging process
Composition (wt %) temperature thickness processing Temperature
Holding time No. Ti Others (.degree. C.) (mm) ratio (%) (.degree.
C.) (hr) 24 1.5 -- 680 8.0 97 420 6 25 0.009 Zn1.5, Cr0.30, 680 8.0
97 420 6 Zr0.15 26 5.5 Ni0.50, P0.15 720 35 *) Cracked during hot
rolling 27 4.0 Zn4.2, Ni1.20, 720 8.5 *) Cracked during cold
rolling Si0.50 28 2.8 Zn4.2, Ni1.30, 700 8.0 96 380 6 Si0.40 29 3.1
Zn1.5, Ni1.50, 700 8.0 96 380 6 Sn1.10, P0.30 30 3.0 -- 580 25 *)
Cracked during hot rolling 31 2.9 Zn1.5 580 15 *) Cracked during
cold rolling 32 3.2 -- 700 10 85 360 6 33 2.7 Zn1.0, In0.30, 720 10
90 360 6 P0.15 34 3.1 Zn1.5, Fe0.35, 700 8.0 97 200 6 Mn0.15 35 3.1
Zn1.8, Sn0.50 700 8.0 96 450 50 36 3.0 -- 700 8.5 98 650 0.5 37 2.9
-- 720 8.5 98 450 0.5 38 2.8 -- 750 8.0 96 200 50 39 2.9 -- 730 8.5
97 -- -- 40 3.2 -- 700 8.0 97 -- -- *) Not examined after
cracking
[0070] From the sheet obtained in this manufacturing process,
various test pieces were sampled, and were subjected to material
tests. The strength was evaluated by the tensile test according to
JIS Z 2241, and the 0.2% proof stress, tensile strength, and
elongation were evaluated. The test pieces were No. 13B type test
pieces conforming to JIS Z 2201. The electrical conductivity was
measured according to JIS H 0505. Results of measurements are shown
in Tables 8 and 9.
TABLE-US-00008 TABLE 8 Evaluation of high strength titanium copper
alloys of the invention Tensile strength 0.2% proof stress
Elongation Electrical Conductivity No. (MPa) (MPa) (%) (% I ACS)
Evaluation 1 1230 1180 3 10.2 Superior 2 1270 1220 3 11.3 Superior
3 1290 1240 2 11.2 Superior 4 1310 1260 2 10.3 Superior 5 1300 1220
2 11.4 Superior 6 1310 1240 2 10.3 Superior 7 1290 1220 3 11.5
Superior 8 1300 1250 3 10.4 Superior 9 1260 1200 4 10.3 Superior 10
1280 1220 3 11.7 Superior 11 1270 1200 2 11.2 Superior 12 1250 1180
4 12.3 Superior 13 1290 1210 3 12.2 Superior 14 1280 1230 3 11.1
Superior 15 1310 1250 2 10.0 Superior 16 1270 1210 3 11.1 Superior
17 1280 1210 3 12.0 Superior 18 1290 1230 2 10.8 Superior 19 1260
1200 4 11.6 Superior 20 1300 1240 3 10.4 Superior 21 1280 1220 3
12.1 Superior 22 1280 1230 2 12.0 Superior 23 1270 1220 2 11.7
Superior
TABLE-US-00009 TABLE 9 Evaluation of high strength titanium copper
alloys of comparative examples Tensile strength 0.2% proof stress
Elongation Electrical Conductivity No. (MPa) (MPa) (%) (% I ACS)
Evaluation 24 780 720 2 26.4 Poor 25 800 720 2 55.1 Poor 26 -- --
-- -- Not evaluated 27 -- -- -- -- Not evaluated 28 1280 1220 1 8.0
Poor 29 1280 1220 1 7.8 Poor 30 -- -- -- -- Not evaluated 31 -- --
-- -- Not evaluated 32 1160 1090 1 10.3 Poor 33 1180 1100 1 10.1
Poor 34 1210 1100 1 5.7 Poor 35 1040 940 2 13.2 Poor 36 1060 1000 1
13.1 Poor 37 1250 1160 1 8.0 Poor 38 1230 1130 1 5.8 Poor 39 1220
1120 1 6.0 Poor 40 1250 1160 2 5.8 Poor
[0071] All examples of the invention in Table 8 recorded a tensile
strength of 1200 MPa or more as required in a fork-shaped
connector, and in particular, examples Nos. 4 to 6, 8, 15, and 20
exhibited a tensile strength of 1300 MPa or more. However, in the
comparative examples shown in Table 9, No. 26, 27, 30, and 31
cracked during hot or cold rolling, and the manufacturing
efficiency was poor, and the characteristics thereof could not be
evaluated. That is, No. 26 and 27 were too high in Ti content, and
No. 26 cracked in hot rolling, and although hot rolled to a
thickness of 35 mm, subsequent processing was not continued. No. 27
did not crack in hot rolling; however, edge cracking occurred in
the subsequent cold rolling. No. 30 and 31 were low in aging
temperature, and the temperature was below 600.degree. C. at a
thickness of 25 mm and 15 mm, respectively, and edge cracking
occurred in cold rolling after hot rolling.
[0072] No. 24 is low in Ti content, and it is hence low in
strength. No. 25 is also low in Ti content, and it is an example of
a Cu--Cr--Zr copper alloy, and although the electrical conductivity
is high, the strength is low. No. 28 and 29 are high in contents of
Zn and others, and the electrical conductivity is low, and No. 29
formed edge cracking during cold rolling.
[0073] No. 32 and 33 are too low in workability of cold rolling,
and the strength is low. No. 34 and 38 are low in aging
temperature, and in spite of a long aging period of 50 hours for
No. 38, desired electrical conductivity is not achieved. No. 37 has
a short aging period, and desired electrical conductivity is not
achieved. Nos. 35 and 36 are high in aging temperature or have long
aging periods, and also because the working ratio of cold rolling
before the aging process is high, it results in over-aging, and
high strength is not obtained.
[0074] Nos. 39 and 40 are similar to alloys of Nos. 3 and 4 of the
invention manufactured in the same process up to cold rolling, but
are not aged, and although a high strength of 1200 MPa or more is
obtained by cold rolling at high working ratio, the electrical
conductivity is low, and they cannot be used in fork-shaped
connector.
[0075] Thus, the titanium copper of the invention can be obtained
only by the manufacturing method of the invention, and it is a
titanium copper alloy having a tensile strength of 1200 MPa or more
and an electrical conductivity of 10% IACS or more, not obtainable
in the conventional art. The fork-shaped connector using the high
strength titanium copper of the invention has a contact pressure
equivalent to that of beryllium copper.
Example 4
[0076] Of the materials manufactured up to the cold rolling
processing in Table 6 in example 3, those listed in Table 10 were
selected and press worked. These press worked test pieces were aged
in the same condition as in example 3. Characteristics of test
pieces were investigated before and after the aging process in the
same method as in example 3, and the results are recorded in Table
10. To evaluate the thermal expansion and shrinkage rate, a test
piece of 100 mm.times.10 mm was cut out in a parallel direction to
rolling direction, the distance between specified marking positions
was measured by using a three-dimensional coordinate measuring
apparatus, and the marking position distance was measured again
after the aging process, and the dimension change rate was
determined from the measurements before and after heating. By way
of comparison, using the material shown in Table 7 and beryllium
copper, test pieces were prepared under the same condition
aforementioned, and the characteristics were measured in the same
method. The results are shown in Table 10.
TABLE-US-00010 TABLE 10 Evaluation of high strength titanium copper
alloys of the invention Characteristic before Characteristic after
aging process aging process Electrical 0.2% Electrical Tensile
Elon- Con- Tensile proof Elon- Con- Thermal Composition strength
gation ductivity strength stress gation ductivity Hardness
expansion/ No. wt % MPa % % I ACS MPa MPa % % I ACS Hv shrinkage %
Evaluation 1 2.3Ti 1100 2 7 1230 1180 3 10 350 0.06 Superior 2
2.9Ti 1170 2 7 1290 1240 2 11 360 0.05 Superior 3 3.4Ti 1180 1 5
1300 1220 2 11 370 0.05 Superior 4 2.9Ti--1.0Zn--0.2Fe 1160 1 5
1290 1220 3 12 360 0.06 Superior 5 2.5Ti--0.10Cr 1140 2 6 1260 1200
4 10 350 0.06 Superior 6 3.2Ti--0.20Fe 1150 1 5 1270 1200 2 11 350
0.06 Superior 7 3.2Ti--0.25In 1160 1 5 1290 1210 3 12 360 0.05
Superior 8 3.1Ti--0.07P 1180 2 4 1310 1250 2 10 37 0.05 Superior 9
3.1Ti--0.15Sn--0.10P 1140 1 5 1260 1200 4 12 350 0.06 Superior 10
2.9Ti--0.8Zn--0.25Ni--0.05Sn 1160 2 4 1280 1220 3 12 350 0.05
Superior 11 1.5Ti 650 3 7 780 720 2 26 250 0.04 Poor 12
2.5Ti--4.2Zn--1.30Ni--0.40Sn 1140 1 3 1280 1220 1 8 340 0.05 Poor
13 2.7Ti--1.0Zn--0.30In--0.15P 1060 1 5 1180 1100 1 10 320 0.04
Poor 14 3.1Ti--1.5Zn--0.35Fe--0.15Mn 1170 2 3 1210 1100 1 6 320
0.05 Poor 15 3.1Ti--1.8Zn--0.50Sn 980 2 5 1040 940 2 13 310 0.05
Poor 16 1.9Be--0.25Co--Cu 560 15 16 1300 1200 3 25 380 0.11
Shrinkage inferior
[0077] As can be seen from Table 10, in Nos. 1 to 10 in example 4,
the strength after the aging process was equivalent to that of
beryllium copper (No. 16), and a high electrical conductivity was
obtained. In contrast, with No. 11, the titanium content was less
than 2.0% by mass, and the tensile strength was low. In No. 16, the
thermal expansion and shrinkage rates were extremely large.
[0078] According to the invention, as described herein, the
titanium copper alloy is increased in strength without sacrificing
the bending properties, and the required characteristics as the
terminal connector for electronic component can be improved, so
that a material for a terminal connector of high reliability can be
presented. In the examples of the invention, the titanium copper
alloy has a tensile strength of 1200 MPa or more and an electrical
conductivity of 10% IACS, and it is increased in strength to a
level equal to that of beryllium copper, and it is improved so as
to be a copper alloy suited for use in terminal connectors for
electronic component, in particular, for fork-shaped connector for
FPCs, and it is shown to be usable sufficiently as a substitute
copper alloy for beryllium copper alloy. IN addition, if the
contact of the terminal connector is plated before or after
working, the strength is hardly changed, and the effects of the
invention are unchanged.
* * * * *