[Technical Field]
[0001] The present invention is related to a titanium copper for electronic components which
is suitable for electronic components, particularly connectors, battery terminals,
jacks, relays, switches, autofocus camera modules, lead frames, and a method for manufacturing
the titanium copper.
[Background Art]
[0002] In recent years, the miniaturization of electronic components such as lead frames,
connectors which are used in electrical or electronic equipment and in-vehicle parts,
has progressed, and there is a remarkable trend toward narrow pitch and low height
for copper alloy members constituting electronic components. The smaller the connector
is, the smaller the pin width is, and the smaller the folded work shape is. Therefore,
the copper alloy members are required to have high strength to obtain the necessary
spring characteristics. In this regard, a copper alloy containing titanium (hereinafter
referred to as "titanium copper") has a relatively high strength and is excellent
in stress relaxation characteristics among copper alloys. Therefore, titanium copper
has been used for a long time as a material for signal terminals, whose strength is
particularly required.
[0003] Titanium copper is an age hardening type copper alloy. When a supersaturated solid
solution of Ti (which is a solute atom) is formed by the solution heat treatment,
and heat treatment for a relatively long time at a low temperature is performed from
this state, a modulation structure, in which the Ti concentration in the parent phase
fluctuates periodically, develops and results into improvement of strengthen, because
of spinodal decomposition. In the case, the problem is that the strength and the bending
workability are contradictory properties. That is, if the strength is increased, the
bending workability is impaired, and on the contrary, when emphasis is placed on the
bending workability, the desired strength can not be obtained. In general, the higher
the reduction ratio of cold rolling is, the larger the introduced amount of dislocation
is, and the higher the dislocation density is. And thus, the number of nucleation
sites contributing to precipitation increases, and the strength after aging treatment
can be increased. However, when the reduction ratio is too high, the bending workability
deteriorates. For This reason, it has been a problem to achieve both strength and
bending workability.
[0004] Under this circumstance, Patent Document 1 (
JP2013-100586A) discloses a titanium copper comprising Ti of 1.5 to 5.0 mass%, and the rest consisting
of copper and inevitable impurities, having a tensile strength of 800 MPa or more,
wherein when an EBSD measurement is carried out parallel to the plate thickness direction
at the central portion in the plate thickness direction which is a cross sectional
position of 45 to 55% with respect to the thickness, and when the crystal orientation
is analyzed, the area ratio of Cube orientation {001} <100> Is 5% or more, the area
ratio of Brass orientation {110} <112> is 40% or less, and the area ratio of Copper
orientation {112} <111> is 20% or less. According to this disclosure, by controlling
the crystal orientation inside the copper alloy plate in this way, it is possible
to obtain sufficient bending workability for notch bending.
[0005] Further, Patent Document 2 (
WO2012/029717) discloses a copper alloy sheet material containing 1.0 to 5.0 mass% of Ti and the
rest consisting of copper and inevitable impurities, wherein in the crystal orientation
analysis by EBSD measurement, the copper alloy sheet material is characterized in
that the area ratio of the Cube orientation {001} <100> is 5 to 50%. According to
the disclosure, there is a correlation between the Cube orientation accumulation ratio
and the bending workability, and by controlling this, a copper alloy sheet material
having excellent bending workability and excellent strength can be obtained.
[0006] Further, Patent Document 3 (
JP2015-190044A) discloses that, at the stage before finish cold rolling, by controlling the ratio
of the maximum side average crystal grain size / average grain size to be smaller
than a certain level, and by reducing the number density of coarse second phase particles,
the level of the bending workability of the copper alloy sheet material can be improved
and variations can be reduced. Moreover, Patent Document 4 (
JP2004-052008A) discloses a titanium copper alloy material comprising Ti of 1.0 to 5.0 mass% and
the rest consisting of copper and inevitable impurities, characterized in that the
value of the ratio of (the deviation of crystal grain size) / (the average crystal
grain size) is 0.60 or less, and the mechanical properties such as bending workability
and stress relaxation property of the titanium copper alloy material are uniform and
good.
Citation List
[Patent Document]
[Summary of Invention]
[Technical Problem to Be Solved]
[0008] Meanwhile, for the purpose of ensure clicking feeling during mounting, some of the
materials for signal terminals are subjected to a beating process on both sides of
the terminal in advance so as to reduce the plate thickness and then subjected to
a bending process as before. At this time, the problem is that, since processing strain
is introduced due to the beating process, when compared with the state in which the
beating process is not conducted, the bending workability is impaired. For this reason,
maintaining bending workability even when a beating process is conducted, is considered
a problem. Although the inventions described in Patent Documents 1 to 4 have certain
effects in improving the bending workability, in order to respond to the requirement
of bending workability of titanium copper for electronic components to which beating
process is applied, further improvement is desired.
[0009] Therefore, it is an object of present invention to improve bending workability of
titanium copper for electronic components, and to provide a titanium copper for electronic
components, which has excellent bending workability even when subjected to beating
process, and to provide a method for manufacturing the same.
[Solution to Problem]
[0010] In order to solve the above technical problem, the inventors of the present invention
conducted extensive research and discovered findings that, in order to improve the
bending workability of titanium copper for electronic components to which beating
process is applied, it is important to simultaneously control the coefficient of variation
of crystal grain size when orientation difference of 5° or more is defined as a crystal
grain boundary, and the area ratio of Cube orientation {001} <100>.
[0011] Besides, the inventors also discovered finding that, to realize the control described
above, when manufacturing a titanium copper by hot rolling an ingot of titanium copper,
followed by a step of cold rolling and a final solution heat treatment, it is necessary
to make the minimum working ratio per pass and the total working degree in the step
of cold rolling within a certain range, while setting the rate of temperature rise
and the heating temperature in the step of final solution heat treatment in a certain
range.
[0012] The present invention is accomplished based on the above findings.
[0013] Accordingly, the present invention is described as below:
- (1) A titanium copper, comprising 2.0 to 4.5 mass% of Ti, and at least one element
in total selected from the group consisting of Fe, Co, Ni, Cr, Zn, Zr, P, B, Mo, V,
Nb, Mn, Mg, and Si in total of 0 to 0.5 mass% as a third element(s), and the rest
consisting of copper and inevitable impurities,
wherein in a crystal orientation analysis by EBSD measurement on the rolled surface,
when an orientation difference of 5° or more is defined as a crystal grain boundary,
a coefficient of variation of crystal grain size is 45% or less, and an area ratio
of Cube orientation {001} <100> is 5% or less.
- (2) The titanium copper according to (1), wherein when a W bending test was performed
in the Badway direction at r/t = 1.0 in accordance with JIS-H 3130 (2012) after a
cold rolling with a working ratio of 10%, the average roughness Ra of the outer peripheral
surface of the bent portion is 1.0 µm or less.
- (3) The titanium copper according to (1) or (2), wherein in the crystal orientation
analysis by EBSD measurement on the rolled surface, when an orientation difference
of 5° or more is defined as a crystal grain boundary, an average crystal grain size
is 2 to 30 µm.
- (4) The titanium copper according to any one of (1) to (3), wherein when a tensile
test is performed according to JIS-Z 2241 (2011), a 0.2% yield strength in a direction
parallel to the rolling direction is 800 MPa or more.
- (5) An electronic component, comprising the titanium copper according to any one of
(1) to (4).
- (6) A method for manufacturing the titanium copper according to any one of (1) to
(4), the method comprising:
a step of hot rolling an ingot of titanium copper, the ingot comprising 2.0 to 4.5
mass% of Ti, and at least one element selected from the group consisting of Fe, Co,
Ni, Cr, Zn, Zr, P, B, Mo, V, Nb, Mn, Mg, and Si in total of 0 to 0.5 mass% as a third
element(s), and the rest consisting of copper and inevitable impurities;
a step of cold rolling; and subsequently
a step of final solution heat treatment;
wherein in the step of cold rolling before the step of final solution heat treatment,
the minimum working ratio per pass is 10 to 30%, and when the total working degree
η is indicated as η = In {(thickness before cold rolling) / (thickness after cold
rolling)}, the η is 1.0 or more and less than 3.0; and
wherein in the step of final solution heat treatment, when the addition amount (mass%)
of Ti is X, the final heating temperature (°C) is (52 x X + 610) to (52 x X + 680),
the rate of temperature rise from 400 °C to the final heating temperature is 20 to
30 °C/s, and the duration of the final solution heat treatment is from 30 seconds
to 10 minutes.
[Effect of Invention]
[0014] According to the present invention, bending workability of titanium copper for electronic
components can be improved, and a titanium copper for electronic components, which
has excellent bending workability even when subjected to beating process, as well
as a method for manufacturing the same, can be provided.
[Description of Embodiments]
(Ti Concentration)
[0015] In the titanium copper according to the present invention, the Ti concentration is
set to 2.0 to 4.5 mass%. In the titanium copper, Ti is solidified in the Cu matrix
by solution treatment, and fine precipitates are dispersed in the alloy by aging treatment,
thereby increasing strength and conductivity.
[0016] When the Ti concentration is less than 2.0 mass%, precipitation of precipitates becomes
insufficient and desired strength cannot be obtained. When the Ti concentration exceeds
4.5% by mass, the processability is deteriorated, and the material is easily broken
during rolling. Considering the balance of strength and workability, the preferable
Ti concentration is 2.5 to 3.5 mass%.
(Third Element(s))
[0017] In the titanium copper according to the present invention, one or more third element(s)
selected from the group consisting of Fe, Co, Ni, Cr, Zn, Zr, P, B, Mo, V, Nb, Mn,
Mg and Si can be contained, and thereby the strength can be further improved. However,
when the total concentration of the third element(s) exceeds 0.5% by mass, the processability
is deteriorated, and the material is easily broken during rolling. Therefore, these
third elements can be contained in a total amount of 0 to 0.5 mass%. In view of the
balance between strength and workability, it is preferable to contain one or more
of the above elements in a total amount of 0.1 to 0.4 mass%. Further, for each additional
element, Zr, P, B, V, Mg and Si in an amount of 0.01 to 0.15 mass%, Fe, Co, Ni, Cr,
Mo, Nb and Mn in an amount of 0.01 to 0.3 mass%, and Zn in an amount of 0.1 to 0.5
mass%, may be contained.
(Coefficient of Variation of Crystal Grain Size)
[0018] The titanium copper according to the present invention is characterized in that the
relative variation in crystal grain size is small. This variation is evaluated using
a coefficient of variation calculated from the average crystal grain size and standard
deviation, particularly, from the formula: standard deviation / average crystal grain
size x 100. The value of the coefficient of variation is set to 45% or less.
[0019] If the coefficient of variation of crystal grain size is within the above range,
variations in crystal grain size can be suppressed, and dislocation becomes uniform,
and stress at the time of bending is dispersed, and improvement in bending workability
can be expected. From this viewpoint, the coefficient of variation of crystal grain
size is preferably 43% or less, more preferably 41% or less, still more preferably
39% or less.
[0020] Besides, the average crystal grain size and the standard deviation are obtained by
analyzing crystal orientation with the EBSD (Electron Back Scatter Diffraction) measurement
on the rolled surface, using analysis software attached to EBSD (e.g. OIM Analysis
provided by TSL Solutions Co., Ltd.), wherein the average crystal grain size and the
standard deviation are calculated when an orientation difference of 5° or more is
defined as a grain boundary.
[0021] In the present invention, the following conditions are adopted as measurement conditions
in the EBSD measurement.
(A) SEM conditions
[0022]
- Beam condition: acceleration voltage 15 kV, irradiation current amount 5 x 10-8 A
- Working distance: 25 mm
- Observation visual field: 200 µm x 200 µm
- Observation surface: rolled surface
- Pretreatment of the observation surface: electrolytic polishing in a solution of phosphoric
acid 67% + sulfuric acid 10% + water under a condition of 15 V x 60 seconds to expose
the structure
(B) EBSD conditions
[0023]
- Measurement program: OIM Data Collection
- Data analysis program: OIM Analysis (Ver.5.3)
- Step width: 0.5 µm
(Area Ratio of Cube Orientation)
[0024] In the titanium copper according to the present invention, the area ratio of the
Cube orientation {001} <100> is controlled to 5% or less. If the area ratio of the
Cube orientation is 5% or less, in combination with the coefficient of variation of
the crystal grain size described above, the bending workability of the titanium copper
according to the present invention can be improved.
[0025] The reason for improving the bending workability of titanium copper is not clear,
but it is presumed as follows. That is, when bending is applied, plastic deformation
normally occurs, and strain accumulates in crystal grains. However, the Cube orientation
is hard to be plastically deformed, and strain is hard to be introduced by bending
processing. When the proportion of Cube orientation increases, the accumulation of
strain becomes unbalanced and cracks are generated due to the locally accumulated
strain. On the contrary, when the proportion of Cube orientation is small, the accumulation
of strain becomes uniform and bending workability is improved. Furthermore, by reducing
crystal grain size, the amount of strain accumulated in each crystal grain size is
reduced, and the bendability is improved.
[0026] Herein, the Cube orientation refers to a state in which the (001) plane is oriented
in the normal direction (ND) of the rolled surface and the (100) plane is in the rolling
direction (RD) in crystal orientation analysis by EBSD measurement on the rolled surface.
It is indicated by an index of {001} <100>.
(Bending Workability)
[0027] The titanium copper according to the present invention can have excellent bending
workability. In one embodiment of the titanium copper according to the present invention,
when a cold rolling with a working ratio of 10%, which simulates a beating process,
is conducted, and subsequently a W bending test was performed in the Badway direction
at r/t = 1.0 in accordance with JIS-H 3130 (2012) after the cold rolling, the average
roughness Ra of the outer peripheral surface of the bent portion is 1.0 µm or less.
The average roughness Ra is calculated according to JIS-B 0601 (2013). The fact that
the average roughness of the bent portion is small even after the bending means that
harmful cracks which may cause breakage are difficult to occur in the bent portion.
Generally, the average roughness Ra of the surface of the titanium copper according
to the present invention before the bending test is 0.2 µm or less.
[0028] The working ratio, which simulates a beating process, is based on the following equation.
In the equation, T
0 is the thickness of the ingot before the cold rolling and T is the thickness of the
ingot at the end of the cold rolling.
(Average Crystal Grain Size)
[0029] From the viewpoint of improving strength, bending workability and fatigue characteristics
in a well-balanced manner, in one embodiment of titanium copper according to the present
invention, it is preferable to control the average crystal grain size in the rolled
surface within the range of 2 to 30 µm, more preferably in the range of 2 to 15 µm,
and still more preferably in the range of 2 to 10 µm.
[0030] As with the average crystal grain size used to calculate the coefficient of variation
of crystal grain size described above, the average crystal grain size means the average
crystal grain size obtained by analyzing the crystal orientation in the EBSD (Electron
Back Scatter Diffraction) measurement on the rolled surface, using analysis software
attached to EBSD (e.g. OIM Analysis provided by TSL Solutions Co., Ltd.), wherein
the average crystal grain size is calculated when an orientation difference of 5°
or more is defined as a grain boundary.
(0.2% Yield Strength)
[0031] In some embodiments of the titanium copper according to the present invention, 0.2%
yield strength in a direction parallel to the rolling direction may be 800 MPa or
more. The 0.2% yield strength of titanium copper according to the present invention
may be 850 MPa or more in a preferred embodiment, 900 MPa or more in a further preferred
embodiment, and 950 MPa or more in a further preferred embodiment.
[0032] The upper limit of the 0.2% yield strength is not particularly restricted from the
viewpoint of the strength intended by the present invention, but since it is troublesome
and expensive, the 0.2% yield strength of titanium copper according to the present
invention is generally 1300 MPa or less, typically 1200 MPa or less, more typically
1100 MPa or less.
[0033] In the present invention, the 0.2% yield strength in the direction parallel to the
rolling direction is measured in accordance with JIS-Z 2241 (2011) (method for metal
material tensile test).
(Thickness of Titanium Copper)
[0034] In one embodiment of titanium copper according to the present invention, the thickness
can be 1.0 mm or less. In a typical embodiment, the thickness can be 0.02 to 0.8 mm,
and in an more typical embodiment, the thickness can be 0.05 to 0.5 mm.
(Application)
[0035] Titanium copper according to the present invention can be processed into various
copper elongation products such as plates, strips, pipes, rods and wires. The titanium
copper according to the present invention is preferably used as a conductive material
or a spring material in electronic components such as a switch, a connector, an autofocus
camera module, a jack, a terminal (in particular, a battery terminal), a relay and
the like, although its application is not limited. These electronic components can
be used, for example, as in-vehicle parts or parts for electrical and electronic equipment.
(Manufacturing Method)
[0036] Hereinafter, preferable production examples of the titanium copper according to the
present invention will be sequentially described for each step.
<Preparation of Ingot>
[0037] Preparation of ingot by melting and casting is basically carried out in vacuum or
in an inert gas atmosphere. If undissolved residues of the added element(s) is present
during dissolution, it does not work effectively for improving the strength. Therefore,
in order to eliminate undissolved residues, for third elements having a high melting
point such as Fe or Cr, after add the element, it is necessary to sufficiently stir
it, and to maintain a certain period of time. On the other hand, since Ti is relatively
soluble in Cu, it may be added after dissolution of the third element(s). Therefore,
it is desirable to at first add one or more elements selected from the group consisting
of Fe, Co, Ni, Cr, Zn, Zr, P, B, Mo, V, Nb, Mn, Mg and Si in total of 0 to 0.5 mass%,
and then add Ti to a concentration of 2.0 to 4.5 mass%, so as to produce an ingot.
<Homogenization Annealing and Hot Rolling>
[0038] Since solidifying segregation and crystallization that occurred at the time of preparation
of ingot are coarse, it is desirable to solidify them in the matrix to make them smaller,
and more desirable to eliminate them as much as possible by homogenization annealing.
This is because it is effective in preventing bending cracks. Specifically, after
the ingot preparation process, it is preferable to perform homogenization annealing
by heating to 900 to 970 °C and keeping for 3 to 24 hours, and then to perform hot
rolling. In order to prevent liquid metal brittleness, it is preferable to set the
temperature to 960 °C or less before and during the hot rolling, and to set the temperature
to 900 °C or more during passes from the original thickness to the total reduction
rate of 90%.
<Cold Rolling and Annealing>
[0039] After the hot rolling, cold rolling is performed. The working ratio of the cold rolling
is typically 30% or more.
[0040] Subsequently, annealing can then be carried out. Here, the annealing conditions are
typically 900 ° C. and 1 to 5 minutes. The cold rolling and the annealing can be repeated
as necessary.
<First Solution Heat Treatment>
[0041] After appropriately repeating the cold rolling and the annealing, it is preferable
to perform a first solution heat treatment. Here, the reason for preliminarily performing
solution heat treatment is to reduce the burden on the final solution treatment. That
is, in the final solution heat treatment, since the second phase particles are already
solutionized, heat treatment for solid solution of the second phase particles is not
necessary, and it is only necessary to maintain this state and further cause recrystallization,
so that a slight heat treatment is sufficient. Specifically, the first solution heat
treatment may be performed at a heating temperature of 850 to 900 °C for 2 to 10 minutes.
It is also preferable to make the heating rate and the cooling rate at that time as
high as possible and to prevent precipitation of the second phase particles during
this process. Note that the first solution heat treatment may not be performed.
<Intermediate rolling>
[0042] The area ratio of the Cube orientation and the coefficient of variation of the crystal
grain size are greatly affected by recrystallization in the final solution heat treatment.
Since the driving force of recrystallization is the strain introduced by intermediate
rolling which is the previous process, it becomes important to control the minimum
working ratio per pass and the total working degree. Here, it is necessary to set
the minimum working ratio per pass to 10 to 30%, and when the total working degree
η is indicated as η = In {(thickness before cold rolling) / (thickness after cold
rolling)}, it is necessary to set the η to 1.0 or more and less than 3.0.
[0043] When the minimum working ratio per pass is less than 10%, it becomes difficult to
control the area ratio of the Cube orientation of finally obtained titanium copper
to 5% or less, whereas if the minimum working ratio per pass exceeds 30%, the material
breaks and the production becomes difficult. From this viewpoint, the minimum working
ratio per pass is preferably 13 to 27%, more preferably 16 to 24%.
[0044] Further, when the total working degree η is less than 1.0, it becomes difficult to
control the coefficient of variation of the crystal grain size of finally obtained
titanium copper to 45% or less, whereas when the total processing degree η is 3 .0
or more, it also becomes difficult to control the coefficient of variation of the
crystal grain size of finally obtained titanium copper to 45% or less. From this viewpoint,
the total working degree η is preferably 1.3 to 2.7, more preferably 1.6 to 2.4.
[0045] The working ratio per pass can be obtained from the following equation. In the equation,
T
0 is the thickness of the ingot before the cold rolling and T is the thickness of the
ingot at the end of the cold rolling.
<Final Solution Heat Treatment>
[0046] In the final solution heat treatment, it is desirable to completely dissolve the
precipitates, but when heated to a high temperature until precipitates are completely
eliminated, the crystal grains tend to coarsen, so the heating temperature is set
close to the solid solubility limit of the second phase particle composition. Specifically,
when the addition amount (mass%) of Ti is X, the heating temperature (° C.) is set
to (52 x X + 610) to (52 x X + 680). When the heating temperature is lower than 52
x X + 610, recrystallization becomes insufficient, and when the heating temperature
exceeds 52 x X + 680, the crystal grain size becomes coarse, and the bending workability
of finally obtained titanium copper is remarkably deteriorated. Here, it is necessary
to control the rate of temperature rise at 400 °C or higher to 20 to 30 °C/s. In the
temperature range of 400 °C or higher, when the rate of temperature rise is less than
20 °C/s, precipitation occurs during the temperature rising process because the heating
time is prolonged, and when the rate of temperature rise exceeds 30 °C/s, As the time
is shortened, it becomes an unstable heat treatment, and as a result, it becomes difficult
to control the coefficient of variation of the crystal grain size of finally obtained
titanium copper to 45% or less.
[0047] In addition, shorter heating time in the final solution heat treatment can suppress
coarsening of crystal grains. Thus the heating time is 30 seconds to 10 minutes, and
typically 1 minute to 8 minutes. During this period, even if second phase particles
are generated, as long as they are finely and uniformly dispersed, they are almost
harmless to strength and bending workability. However, coarse particles tend to grow
further in the final aging treatment, so if second phase particles are generated during
this period, they should be made as few as possible and should be made as small as
possible.
<Final Cold Rolling>
[0048] The final solution heat treatment is followed by the final cold rolling. Although
the strength can be increased by the final cold rolling, in order to obtain bending
workability as intended in the present invention, it is desirable set to the reduction
ratio to 5 to 50%, preferably to 20 to 40%.
<Aging treatment>
[0049] The final cold rolling is followed by aging treatment. It is preferable to heat at
a material temperature of 300 to 500 °C for 1 to 50 hours, more preferably at a material
temperature of 350 to 450 °C for 10 to 30 hours. The aging treatment is preferably
performed in an inert atmosphere such as Ar, N
2, H
2 or the like in order to suppress the generation of the oxide film.
[0050] Summarizing the above, in one embodiment of the method for manufacturing titanium
copper according to the present invention, the method comprises:
a step of preparing an ingot of titanium copper, the ingot comprising 2.0 to 4.5 mass%
of Ti, and at least one element selected from the group consisting of Fe, Co, Ni,
Cr, Zn, Zr, P, B, Mo, V, Nb, Mn, Mg, and Si in total of 0 to 0.5 mass% as a third
element(s), and the rest consisting of copper and inevitable impurities;
a step of hot rolling the ingot;
a step of cold rolling, wherein the minimum working ratio per pass is 10 to 30%, and
when the total working degree η is indicated as η = In {(thickness before cold rolling)
/ (thickness after cold rolling)}, the η is 1.0 or more and less than 3.0; and
a step of final solution heat treatment, wherein when the addition amount (mass%)
of Ti is X, the heating temperature (°C) is (52 x X + 610) to (52 x X + 680), and
the rate of temperature rise at 400 °C or higher is 20 to 30 °C/s.
[0051] Those skilled in the art will appreciate that steps such as grinding, polishing,
shot-blast acid washing and the like for removing oxide scales on the surface can
be appropriately performed between the above steps.
[Examples]
[0052] Hereinafter, the present invention will be specifically described using examples
and comparative examples. However, The descriptions of the following examples and
comparative examples are merely specific examples for facilitating understanding of
the technical contents of the present invention and the technical scope of the present
invention is not limited by these specific examples.
[0053] Alloys containing the alloy components shown in Table 1 and the rest consisting of
copper and inevitable impurities were used as an experimental materials and effects
of the alloy components, the production conditions for cold rolling and subsequent
final solution heat treatment on the 0.2% yield strength, the coefficient of variation
of crystal grain size, the area ratio of Cube orientation and the bending workability
after rolling were investigated.
[0054] First, 2.5 kg of electrolytic copper was dissolved in a vacuum melting furnace, and
third element(s) was added at the mixing ratio shown in Table 1, and then Ti of the
compounding ratio shown in the same table was added. After carefully considering the
retention time after addition so that there is no residue of added elements, these
were injected into a mold in Ar atmosphere to produce ingots of about 2 kg each.
[0055] After homogenizing annealing to the ingot at 950 °C for 3 hours, hot rolling was
performed at 900 to 950 °C to obtain a hot rolled sheet having a thickness of 15 mm.
After descaling by surface milling, cold rolling and annealing were repeated to obtain
strip thicknesses (0.3 to 3.3 mm), and a first solution heat treatment was performed
on the stripes. The conditions of the first solution heat treatment were heating at
850 °C for 10 minutes and then water cooling. Subsequently, intermediate cold rolling
was carried out under the conditions shown in Table 1, then inserted into an annealing
furnace which is capable of rapid heating, and the final solution treatment was performed,
followed by water cooling. The heating conditions at this time were set as shown in
Table 1. Then, after descaling by acid washing, final cold rolling with a reduction
ratio of 25% was performed to obtain a plate thickness of 0.1 mm and finally subjected
to aging treatment at 400 °C x 20 hours to obtain test pieces of the Examples and
Comparative Examples Respectively.
[0056] The following tests were conducted on the prepared test pieces.
(0.2% yield strength)
[0057] JIS 13B test piece was prepared and the 0.2% yield strength in the direction parallel
to the rolling direction was measured using a tensile tester according to the above
measuring method.
(Average crystal grain size)
[0058] After polishing the plate surface (rolled surface) of each test piece and etching
it, in the analysis of crystal orientation by EBSD (Electron Back Scatter Diffraction)
measurement, using analysis software attached to EBSD (eg, OIM Analysis provided by
TSL Solutions Co., Ltd.), the average crystal grain size in the case where the orientation
difference of 5° or more was defined as a grain boundary was measured.
(Coefficient of variation of crystal grain size)
[0059] After polishing the plate surface (rolled surface) of each test piece and etching
it, in the analysis of crystal orientation by EBSD (Electron Back Scatter Diffraction)
measurement, using analysis software attached to EBSD (eg, OIM Analysis provided by
TSL Solutions Co., Ltd.), the average crystal grain size and the standard deviation
in the case where the orientation difference of 5° or more was defined as a grain
boundary was measured, and the value of standard deviation / average crystal grain
size x 100 was taken as the coefficient of variation of crystal grain size.
(Area ratio of Cube orientation (%))
[0060] After polishing the plate surface (rolled surface) of each test piece and etching
it, in the analysis of crystal orientation by EBSD (Electron Back Scatter Diffraction)
measurement, the area ratio (%) of the Cube orientation was measured. When the deviation
angle from the Cube orientation was within 15°, it is regarded as in Cube orientation.
(Bendability after rolling)
[0061] A cold rolling with a working ratio of 10%, which simulates a beating process, was
conducted, and subsequently a W bending test was performed in the Badway direction
at r/t = 1.0 in accordance with JIS-H 3130 (2012) after the cold rolling. The outer
peripheral surface of the bent portion of this test piece was observed. For the observation
method, the outer peripheral surface of the bent portion was photographed using a
confocal microscope HD100 manufactured by Lasertec Corporation, and the average roughness
Ra (according to JIS-B 0601: 2013) was measured using the attached software and compared.
When the surface of the sample before bending was observed with a confocal microscope,
irregularities were not confirmed, and the average roughness Ra was 0.2 µm or less
in each case. A case where the surface average roughness Ra after bending was 1.0
µm or less was evaluated as "OK" and a case where Ra was more than 1.0 µm was evaluated
as "NG".
[Table 1]
|
Conditions for production |
Final characteristics |
Component (mass%) |
Cold rolling before final solution heat treatment |
Final solution heat treatment |
Ti |
Third element |
minimum working ratio per pass(%) |
total working degree (η) |
rate of temperature rise at 400 °C or higher (°C/s) |
heating temperature (°C) |
0.2% yield strength (MPa) |
average crystal grain size (µm) |
coefficient of variation of crystal grain size (%) |
Area ratio of Cube orientation (%) |
bendability after rolling |
Example 1 |
3.2 |
0.2Fe |
20 |
2.3 |
25 |
800 |
966 |
5 |
38 |
2.4 |
OK |
Example 2 |
3.2 |
0.2Fe |
12 |
2.3 |
25 |
800 |
956 |
6 |
39 |
4.5 |
OK |
Example 3 |
3.2 |
0.2Fe |
28 |
2.3 |
25 |
800 |
954 |
5 |
35 |
0.8 |
OK |
Example 4 |
3.2 |
0.2Fe |
20 |
1.1 |
25 |
800 |
961 |
6 |
43 |
2.1 |
OK |
Example 5 |
3.2 |
0.2Fe |
20 |
2.9 |
25 |
800 |
960 |
6 |
33 |
2.2 |
OK |
Example 6 |
3.2 |
0.2Fe |
20 |
2.3 |
22 |
800 |
945 |
5 |
42 |
2.6 |
OK |
Example 7 |
3.2 |
0.2Fe |
20 |
2.3 |
28 |
800 |
944 |
6 |
36 |
2.5 |
OK |
Example 8 |
3.2 |
0.2Fe |
20 |
2.3 |
25 |
750 |
956 |
3 |
35 |
2.4 |
OK |
Example 9 |
3.2 |
0.2Fe |
20 |
2.3 |
25 |
840 |
930 |
15 |
39 |
2.0 |
OK |
Example 10 |
3.2 |
- |
20 |
2.3 |
25 |
800 |
925 |
20 |
35 |
3.2 |
OK |
Example 11 |
2.0 |
- |
20 |
2.3 |
25 |
750 |
833 |
25 |
40 |
3.7 |
OK |
Example 12 |
4.5 |
- |
20 |
2.3 |
25 |
880 |
1097 |
20 |
35 |
2.7 |
OK |
Example 13 |
3.2 |
0.2Mo-0.05Mg |
25 |
2.3 |
25 |
820 |
963 |
8 |
36 |
2.9 |
OK |
Example 14 |
3.2 |
0.2Ni-0.05B |
15 |
1.5 |
25 |
790 |
945 |
7 |
42 |
3.8 |
OK |
Example 15 |
3.2 |
0.05Zr-0.05P |
20 |
2 |
25 |
810 |
959 |
13 |
40 |
3.4 |
OK |
Example 16 |
3.2 |
0.4Zn-0.05V |
25 |
1.8 |
25 |
800 |
952 |
16 |
42 |
1.4 |
OK |
Example 17 |
3.2 |
0.2Cr-0.1Mn-0.05Nb |
15 |
2.6 |
25 |
820 |
958 |
14 |
35 |
3.1 |
OK |
Example 18 |
3.2 |
0.2Co-0.05Si |
25 |
2 |
25 |
830 |
948 |
10 |
38 |
2.2 |
OK |
Comparative Example 1 |
3.2 |
0.2Fe |
7 |
2.3 |
25 |
800 |
956 |
7 |
42 |
7.3 |
NG |
Comparative Example 2 |
3.2 |
0.2Fe |
(35) |
Not manufacturable |
- |
- |
- |
- |
- |
Comparative Example 3 |
3.2 |
0.2Fe |
20 |
0.8 |
25 |
800 |
943 |
6 |
51 |
2.6 |
NG |
Comparative Example 4 |
3.2 |
0.2Fe |
20 |
3.2 |
25 |
800 |
952 |
5 |
48 |
2.9 |
NG |
Comparative Example 5 |
3.2 |
0.2Fe |
20 |
2.3 |
16 |
800 |
965 |
5 |
52 |
3.1 |
NG |
Comparative Example 6 |
3.2 |
0.2Fe |
20 |
2.3 |
34 |
800 |
964 |
5 |
50 |
2.4 |
NG |
Comparative Example 7 |
3.2 |
0.2Fe |
20 |
2.3 |
25 |
750 |
975 |
Unrecrystallized |
- |
- |
NG |
Comparative Example 8 |
3.2 |
0.2Fe |
20 |
2.3 |
25 |
850 |
915 |
35 |
53 |
2.4 |
NG |
Comparative Example 9 |
3.2 |
0.3Fe-0.3Ni |
Not manufacturable |
- |
- |
- |
- |
- |
Comparative Example 10 |
1.5 |
0.2Fe |
20 |
2.3 |
25 |
720 |
753 |
5 |
38 |
6.7 |
NG |
Comparative Example 11 |
5.0 |
0.2Fe |
Not manufacturable |
- |
- |
- |
- |
- |
Comparative Example 12 |
3.2 |
- |
8 |
0.9 |
25 |
840 |
|
18 |
43 |
6.6 |
NG |
(Discussions)
[0062] In Examples 1 to 18, the coefficient of variation of the crystal grain size is 45%
or less and the area ratio of the Cube orientation is 5% or less, so that the bending
workability is excellent. Further, the average crystal grain size was 2 to 30 µm,
and the 0.2% yield strength was 800 MPa or more.
[0063] On the other hand, in Comparative Example 1, since the minimum working ratio per
pass was too low, the area ratio of the Cube orientation was outside the range of
the present invention, and the bending workability was inferior to the Examples.
[0064] In Comparative Example 2, the minimum working ratio per pass was too high, and as
a result the material broke and it was impossible to continue production.
[0065] Since the total working degree of Comparative Example 3 and 4 was outside the range
of the present invention, the coefficient of variation of the crystal grain size was
outside the range of the present invention. Therefore, the bending workability was
inferior to the Examples.
[0066] Since the rate of temperature rise in Comparative Example 5 and 6 at 400 °C or higher
was outside the range of the present invention, the coefficient of variation of the
crystal grain size was outside the range of the present invention. Therefore, the
bending workability was inferior to the Examples.
[0067] Since the heating temperature in Comparative Example 7 was too low, recrystallization
was insufficient, and titanium copper intended for the present invention could not
be produced.
[0068] Since the heating temperature in Comparative Example 8 was too high, the coefficient
of variation of the crystal grain size exceeded the upper limit of the present invention.
Therefore, the bending workability was inferior to the Examples.
[0069] Since the third element(s) added to Comparative Example 9 was too much, the material
cracked during rolling, and titanium copper intended for the present invention could
not be produced.
[0070] Since the amount of Ti added to Comparative Example 10 was too small, the area ratio
of the Cube orientation exceeded the upper limit of the present invention. Therefore,
the bending workability was inferior to the Examples.
[0071] Since the amount of Ti added to Comparative Example 11 was too large, the material
cracked during rolling, and titanium copper intended for the present invention could
not be produced.
[0072] Comparative Example 12 was produced in accordance with the invention according to
Patent Document 4 described above. In Comparative Example 12, the minimum working
ratio per pass is low and the total working degree is also low. Moreover, the heating
temperature is higher than the range of the present invention. As a result, the area
ratio of the Cube orientation exceeded the upper limit of the present invention, and
the bending workability was inferior to the Examples.
1. Cuivre-titane, comprenant de 2,0 à 4,5% en masse de Ti, et au moins un élément choisi
dans le groupe constitué par Fe, Co, Ni, Cr, Zn, Zr, P, B, Mo, V, Nb, Mn, Mg et Si
pour un total de 0 à 0,5 % en masse en tant que troisième(s) élément(s), et le reste
se composant de cuivre et d'impuretés inévitables,
dans lequel dans une analyse d'orientation de cristaux par mesure EBSD sur la surface
laminée, lorsqu'une différence d'orientation supérieure ou égale à 5° est définie
comme une limite de grains cristallins, un coefficient de variation de taille de grains
cristallins est inférieur ou égal à 45 %, et un rapport de surface d'orientation cubique
{001} <100> est inférieur ou égal à 5 %.
2. Cuivre-titane selon la revendication 1, dans lequel lorsqu'un test de flexion W a
été réalisé dans la direction Badway à r/t = 1,0 conformément à la norme JIS-H 3130
(2012) après un laminage à froid avec un rapport de travail de 10 %, la rugosité moyenne
Ra de la surface périphérique externe de la partie fléchie est inférieure ou égale
à 1,0 µm.
3. Cuivre-titane selon la revendication 1 ou 2, dans lequel dans l'analyse d'orientation
cristalline par mesure EBSD sur la surface laminée, lorsqu'une différence d'orientation
supérieure ou égale à 5° est définie comme une limite de grains cristallins, une taille
de grains cristallins moyenne est de 2 à 30 µm.
4. Cuivre-titane selon l'une quelconque des revendications 1 à 3, dans lequel lorsqu'un
test de traction est réalisé selon la norme JIS-Z 2241 (2011), une limite d'élasticité
à 0,2 % dans une direction parallèle à la direction de laminage est supérieure ou
égale à 800 MPa.
5. Composant électronique, comprenant le cuivre-titane selon l'une quelconque des revendications
1 à 4.
6. Procédé de fabrication du cuivre-titane selon l'une quelconque des revendications
1 à 4, le procédé comprenant :
une étape de laminage à chaud d'un lingot de cuivre-titane, le lingot comprenant de
2,0 à 4,5 % en masse de Ti, et au moins un élément choisi dans le groupe constitué
par Fe, Co, Ni, Cr, Zn, Zr, P, B, Mo, V, Nb, Mn, Mg et Si pour un total de 0 à 0,5
% en masse en tant que troisième(s) élément(s), et le reste se composant de cuivre
et d'impuretés inévitables ;
une étape de laminage à froid ; et ensuite
une étape de traitement thermique de la solution finale ;
dans lequel dans l'étape de laminage à froid avant l'étape de traitement thermique
de la solution finale, le rapport de travail minimal par passe est de 10 à 30 %, et
lorsque le degré de travail total η est indiqué comme η = In {(épaisseur avant le
laminage à froid) / (épaisseur après le laminage à froid)}, η est supérieur ou égal
à 1,0 et inférieur à 3,0 ; et
dans lequel dans l'étape de traitement thermique de la solution finale, lorsque la
quantité d'addition (% en masse) de Ti est X, la température thermique finale (°C)
est de (52 x X + 610) à (52 x X + 680), la vitesse d'augmentation de température de
400 °C à la température thermique finale est de 20 à 30 C/s, et la durée du traitement
thermique de la solution finale est de 30 secondes à 10 minutes.