JP2012077338A - Copper-titanium alloy and wrought product, electronic component, and connector each using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a copper-titanium alloy having excellent strength and bending workability; and to provide a wrought product, an electronic component, and a connector each using the copper-titanium alloy.SOLUTION: The copper-titanium alloy contains 1.0-5.0 mass% Ti and the balance comprising copper and unavoidable impurities, and is characterized in that when the structure of the rolled surface after being electropolished is observed by means of an electron microscope, the average crystal grain size is 20 μm or less, the average number density (X) of the second phase particles having particle diameters of 1 μm or more and being present within crystal grains is 15×10particles/mmor less, and the average number density (Y) of the second phase particles having particle diameters of 100 nm to 1 μm and being present within crystal grains is 3.5×10to 35×10particles/mm, and when the rolled surface after being electropolished is examined from EBSP (electron back-scattering pattern), the area ratio of crystal grains with orientations within the scope of 20 degrees with respect to the {111} face is 15-90%.

Description

  The present invention relates to titanium copper suitable for a member for electronic parts such as a connector, for example, a drawn copper product using the same, an electronic part and a connector.

  In recent years, electronic devices typified by portable terminals and the like have been increasingly miniaturized, and accordingly, connectors used for such devices tend to have a narrow pitch and a low profile. The smaller the connector, the narrower the pin width and the smaller the folded shape, so the members used will have high strength to obtain the necessary spring properties and excellent bending that can withstand severe bending. Sex is required. In this regard, a titanium-containing copper alloy (hereinafter referred to as “titanium copper”) has a relatively high strength and is most excellent in the copper alloy in terms of stress relaxation characteristics. It has been used for a long time as a signal system terminal member.

  Titanium copper is an age-hardening type copper alloy. When a supersaturated solid solution of Ti, which is a solute atom, is formed by solution treatment and heat treatment is performed at a low temperature for a relatively long time from that state, a modulation structure that is a periodic variation of Ti concentration in the parent phase is caused by spinodal decomposition. Develop and improve strength. At this time, the problem is that the strength and the bending workability are contradictory. That is, if the strength is improved, the bending workability is impaired, and conversely, if the bending workability is emphasized, a desired strength cannot be obtained. In general, the higher the rolling reduction in cold rolling, the more dislocations are introduced and the dislocation density is higher, so that the number of nucleation sites contributing to precipitation increases and the strength after aging treatment can be increased. However, if the rolling reduction is too high, the bending workability deteriorates. For this reason, it has been an object to achieve both strength and bending workability.

  Therefore, a third element such as Fe, Co, Ni, Si or the like is added (Patent Document 1), the concentration of the impurity element group that dissolves in the matrix phase is regulated, and these elements are added to the second phase particles (Cu-Ti- X-type particles) are precipitated in a predetermined distribution form to increase the regularity of the modulation structure (Patent Document 2), and the density of the trace additive elements and second-phase particles effective to refine the crystal grains is specified. From the viewpoints of (Patent Document 3) and refining crystal grains (Patent Document 4), a technique has been proposed which attempts to achieve both the strength and bending workability of titanium copper.

In the case of titanium copper, there are a β phase (TiCu ₃ ) having poor consistency with the α phase as a parent phase and a β ′ phase (TiCu ₄ ) having good consistency, and the β phase has an adverse effect on bending workability. On the other hand, evenly and finely dispersing the β ′ phase contributes to both strength and bending workability, and titanium copper in which the β ′ phase is finely dispersed while suppressing the β phase has also been proposed ( Patent Document 5).

By paying attention to the crystal orientation and controlling the crystal orientation to satisfy I {420} / I ₀ {420}> 1.0 and I {220} / I ₀ {220} ≦ 3.0, the strength and bending A technique for improving workability and stress relaxation resistance has also been proposed (Patent Document 6).

Focusing on the difference between the crystal orientation and the maximum crystal grain size and the minimum crystal grain size, I {420} / I ₀ {420}> 1.0 and I {220} / I ₀ {220} ≦ 4.0 are satisfied. By controlling the crystal orientation and controlling the crystal grain size so that (maximum crystal grain size-minimum crystal grain size) / average crystal grain size is 0.20 or less, strength, bending workability and A technique with improved stress relaxation resistance has also been proposed (Patent Document 7).

Japanese Patent Laid-Open No. 2004-231985 JP 2004-176163 A JP-A-2005-97638 JP 2006-265611 A JP 2006-283142 A JP 2008-308734 A JP 2010-126777 A

Thus, various methods have been studied so far for improving the strength and bending workability of titanium copper, but there is still room for improvement.
Therefore, the present invention attempts to improve the properties of titanium copper from a different viewpoint from the past, and provides titanium copper having excellent strength and bending workability, and a copper-drawn product, an electronic component and a connector using the same. Is an issue.

  The present inventor considered that the titanium copper manufacturing process is carried out by a method different from a conventionally performed method in an examination process for achieving both strength and bending workability. That is, in the past, titanium copper was produced in the order of final solution treatment → cold rolling → aging treatment. In the present invention, titanium copper was produced in the order of final solution treatment → aging treatment → cold rolling. It was found that titanium copper excellent in both strength and bending workability can be obtained by making the final solution treatment and cold rolling in this case appropriate conditions.

  In order to investigate the cause, the present inventor investigated the structure of titanium copper according to the embodiment of the present invention, the crystal grain size, the number density of the second phase particles existing in the crystal grain boundary, and the rolling surface. A feature point was found in the relationship of the orientation of crystal grains on the surface. That is, the titanium copper according to the embodiment of the present invention has a small crystal grain size, there are almost no second phase particles in the crystal grain boundary, and it is specified when the crystal grain orientation is observed from the rolling surface. It was found that the area ratio of the crystal grains facing the orientation was high.

The present invention completed on the basis of the above knowledge is, in one aspect, titanium copper containing 1.0 to 5.0% by mass of Ti and the balance copper and unavoidable impurities, and electropolishing of the rolled surface by an electron microscope In the subsequent observation of the structure of the surface, the average crystal grain size is 20 μm or less, the average number density (X) of second phase particles larger than 1 μm in the crystal grains is 15 × 10 ³ particles / mm ² or less, crystals The average number density (Y) of the second phase particles having a particle diameter of 100 nm to 1 μm existing in the grains is 3.5 × 10 ^{3 to} 35 × 10 ³ particles / mm ² , and the surface after electrolytic polishing of the rolled surface is When measured by EBSP, the proportion of crystal grains in the range of {111} to 20 ° is 15 to 90%.

  In one embodiment of titanium copper according to the present invention, the elongation is 3.0% or more and the tensile strength is 850 MPa or more.

  In another embodiment of the titanium-copper according to the present invention, the average roughness Ra of the bending surface is 2.0 μm or less.

  In still another embodiment of the copper alloy according to the present invention, the third element group includes Mn, Fe, Mg, Co, Ni, Cr, V, Nb, Mo, Zr, Si, B, Ag, Be, and Misch metal. And 1 or 2 or more selected from the group consisting of P and 0 to 1.0% by mass in total.

  In another aspect, the present invention is a copper-drawn product made of the above titanium copper.

  In another aspect of the present invention, an electronic component comprising the titanium copper.

  In another aspect of the present invention, the connector includes the titanium copper.

  ADVANTAGE OF THE INVENTION According to this invention, the titanium copper which has the outstanding intensity | strength and bending workability, the copper-stretched article using this, an electronic component, and a connector are obtained.

It is the photograph which observed the titanium copper which concerns on embodiment of this invention with the electron microscope. It is a perspective view showing the relationship between the azimuth | direction in the EBSP measurement of the titanium copper which concerns on embodiment of this invention, and a rolling direction. It is the schematic which shows the directional relationship of the incident angle of an electron beam and test piece in the case of carrying out EBSP measurement of the titanium copper which concerns on embodiment of this invention. It is an example of the orientation mapping figure at the time of carrying out EBSP measurement of the titanium copper which concerns on embodiment of this invention, and a standard stereo triangle figure.

-Composition of titanium copper-
<Ti content>
If Ti is less than 1.0% by mass, a sufficient strengthening mechanism cannot be obtained due to the formation of the original modulation structure of titanium-copper. On the other hand, if Ti exceeds 5.0% by mass, coarse TiCu is not obtained. ₃ tends to precipitate, and the strength and bending workability tend to deteriorate. Therefore, the content of Ti in the copper alloy according to the embodiment of the present invention is 1.0 to 5.0 mass%, preferably 1.5 to 4.5 mass%, more preferably 2.0. It is -4.0 mass%. Thus, by optimizing the Ti content, both strength and bending workability suitable for electronic components can be realized.

<Third element>
When the third element is added to titanium copper, there is an effect that the crystal grains are easily refined and the strength is improved even if solution treatment is performed at a high temperature at which Ti is sufficiently dissolved. In addition, the predetermined third element promotes the formation of the modulation structure. Further, since it has an effect of suppressing precipitation of TiCu _{3 and the} like, the original age hardening ability of titanium copper can be obtained.

  As the third element, Mn, Fe, Mg, Co, Ni, Cr, V, Nb, Mo, Zr, Si, B, Ag, Be, Misch metal and P are added alone, or two or more kinds are added. Multiple additions may be made. Here, misch metal is a mixture of rare earth elements including Ce, La, Dy, Nd, Y and the like.

  When these elements contain 0.02% by mass or more in total, the effect appears, but when the total exceeds 1.0% by mass, the solid solubility limit of Ti is narrowed and coarse second-phase particles are precipitated. It becomes easy and the strength is slightly improved, but the bending workability is deteriorated. At the same time, the coarse second-phase particles promote roughening of the bent portion and promote die wear during press working. Therefore, one or two selected from the group consisting of Mn, Fe, Mg, Co, Ni, Cr, V, Nb, Mo, Zr, Si, B, Ag, Be, Misch metal and P as the third element group The seeds or more can be contained in a total amount of 0 to 1.0% by mass, and the total amount is 0.02 to 1.0% by mass, preferably 0.05 to 0.5% by mass.

-Surface properties of titanium copper-
<Crystal grain size>
An example of titanium copper according to an embodiment of the present invention is shown in FIG. In order to improve the strength of titanium copper, the smaller the crystal grains, the better. Therefore, a preferable average crystal grain size is 20 μm or less, more preferably 15 μm or less, for example, 5 to 15 μm. Although there is no restriction | limiting in particular about a minimum, In order to recrystallize uniformly without an unrecrystallized area | region, 1 micrometer or more is preferable. In the present embodiment, the “average crystal grain size” was measured by the linear crossing line method of JIS G0551 with respect to the structure observation of the surface after electrolytic polishing of the rolled surface by observation with an optical microscope or an electron microscope.

<Second phase particles>
In the present invention, the “second phase particle” refers to a particle having a composition different from the component composition of the matrix (see, for example, the particle 11 in FIG. 1). The second phase particles are particles mainly composed of Cu and Ti precipitated during various heat treatments. Specifically, the TiCu ₃ particles or the component X of the third element group (specifically, Mn, Fe, Mg) , Co, Ni, Cr, V, Nb, Mo, Zr, Si, B, Ag, Be, Misch metal, and P). Cu-X-based particles and Ti-X-based particles are also included in the "second phase particles".

  In the present invention, the second phase particles are classified into two types, those having a particle size of 100 nm to 1.0 μm and those having a particle size exceeding 1.0 μm, and their average number density (Y), (X) is defined. Yes. Second phase particles having a particle size of 100 nm or more and 1.0 μm or less are mainly precipitated at the time of aging treatment, and second phase particles having a particle size of more than 1.0 μm are mainly precipitated and remain before aging treatment. It was thought that what had been grown further during the aging treatment. Moreover, it is thought that a part of 100 nm-1.0 micrometer was what was not melt | dissolved in the final solution treatment but remained. The reason why the former particle size is set to 100 nm or more is that it is difficult to count too fine second-phase particles.

  Therefore, the average number density (Y) of the second phase particles having a particle size of 100 nm to 1.0 μm reflects the conditions in the solution treatment and the aging treatment, and the average number of second phase particles having a particle size of more than 1.0 μm. The density (X) reflects the heat treatment conditions up to the end of the solution treatment in addition to the conditions in the aging treatment.

  The average number density (Y) of the second phase particles having a particle size of 100 nm to 1.0 μm is determined by intermediate and final solution conditions (solution temperature, holding time) and aging treatment. If the cooling temperature becomes faster during solution treatment, the crystal grain size becomes smaller and the average number density (Y) becomes smaller. Further, when the solution temperature is high and the holding time is long, the average number density (Y) is small. The average number density (Y) decreases when the degree of aging treatment is reduced (eg, low temperature for a short time) and increases when the degree of aging treatment is increased (eg, high temperature for a long time). If the average number density (Y) is too small, the degree of aging treatment is insufficient (sub-aging), and the required strength cannot be obtained. In addition, if the average number density (Y) is too small, the degree of work hardening is small and the strength decreases when cold rolling is performed after aging. On the other hand, even if the average number density (Y) is too large, this indicates that the degree of aging treatment is excessive (overaging), and the strength decreases beyond the aging treatment conditions for obtaining the peak strength, and bending is performed. Sex worsens.

In the titanium copper according to the present embodiment, the average number density (Y) of the second phase particles having a particle diameter of 100 nm or more and 1.0 μm or less, which is observed by a speculum of the surface after electrolytic polishing of the rolled surface, is 3.5 × 10. ^{3 to} 35 × 10 ³ pieces / mm ² is appropriate for obtaining a good balance between strength and bending workability, and more preferably 3.5 × 10 ^{3 to} 22.5 × 10 ³ pieces / mm 2. mm ² , more preferably 4.5 × 10 ³ to 15 × 10 ³ pieces / mm ² , still more preferably 5.5 × 10 ³ to 15 × 10 ³ pieces / mm ² , most preferably 6.5 × 10 ^{3 to} 12 × 10 ³ pieces / mm ² . This number density corresponds to the number density obtained in the case of the overaging condition in the case of conventional titanium copper. In the case of 3.5 × 10 ³ pieces / mm ² or less, the degree of work hardening after the final cold rolling is reduced and the strength is lowered.

  On the other hand, the average number density (X) of the second phase particles having a particle size exceeding 1.0 μm is affected by the aging treatment similarly to the average number density (Y), but the heat treatment conditions before the aging treatment, particularly the final solution. Affected by processing conditions. By appropriately performing the final solution treatment, the second phase particles precipitated in the previous step can be dissolved, but if the conditions of the solution treatment are inappropriate, the second phase particles remain. Or newly deposited. Since the second phase particles having a particle size exceeding 1.0 μm have a greater adverse effect on the strength and bending workability than those having a particle size of 1.0 μm or less, it is desirable that the second phase particles be as small as possible.

Therefore, in a preferred embodiment of the titanium-copper according to the present invention, the average number density (X) of the second phase particles having a particle diameter of more than 1.0 μm observed by surface microscopy is 15 × 10 ³ particles / mm. ² or less, more preferably 12 × 10 ³ pieces / mm ² or less, for example, 1.5 × 10 ^{3 to} 12 × 10 ³ pieces / mm ² .

  In the present invention, the diameter of the second phase particles is defined as the diameter of the smallest circle surrounding the second phase particles when observed with a microscope.

<Crystal orientation>
The titanium copper according to this embodiment is characterized by the area ratio of crystal grains having an orientation within 20 ° from the {111} plane. Since the crystal structure of titanium copper within the range of the components specified in the present invention is a face-centered cubic structure, the surface where the atoms are most dense is the {111} surface, and this surface is called a “slip surface”. By continuing the plastic working such as cold rolling, the crystal rotates, and the orientation of crystal grains gathers in the orientation close to the {111} plane.

  The area ratio of crystal grains having an orientation within 20 ° from the {111} plane is determined by the amount of strain applied to the crystal grains. As the amount of strain increases, the area ratio of crystal grains having an orientation within 20 ° from the {111} plane increases. However, if the area ratio of crystal grains having an orientation in the range of 20 ° or less from the {111} plane is too much, a large amount of strain is accumulated in the crystal grains, so that the bendability is deteriorated. Conversely, if the area ratio of crystal grains having an orientation within 20 ° from the {111} plane is too small, the degree of work hardening may be small and the strength may be insufficient.

  In addition, when manufacturing titanium copper by the conventional procedure (solution treatment → rolling → aging treatment), strain in the crystal grains is released by the aging heat treatment, and the orientation is within 20 ° from the {111} plane. There is no characteristic tendency in the area ratio of crystal grains.

  As a method for measuring the crystal orientation distribution of a crystal material, there is an EBSP method (Electro Back Scattering Pattern). EBSP generated when an electron beam is irradiated to a sample set in the SEM is loaded into a computer, and continuously and automatically analyzed using data of known crystal systems. Position data and crystal orientation data (three-dimensional Euler angle display) are obtained. Furthermore, by calculating ODF (Orient Distribution Function) from the above crystal orientation data by a computer, the crystal orientation of each crystal grain can be displayed in different colors. FIG. 4 shows an example of an orientation mapping diagram and a standard stereo triangle diagram in which crystal orientations are color-coded at a magnification of 3000 times. As shown in the standard stereo triangle diagram of FIG. 4, the titanium copper according to the present embodiment is characterized by the area ratio of crystal grains having an orientation in a range of 20 ° from the {111} plane. In the mapping diagram, the crystal grains 20a to 20l are crystal grains having an orientation within a range of 20 ° from the {111} plane.

In the titanium copper according to the present embodiment, when the rolled surface of titanium copper is textured after electrolytic polishing, the surface is measured by a backscattered electron diffraction image (EBSP) attached to a scanning microscope (SEM). , It is preferable to control so that the area ratio of crystal grains having an orientation within 20 ° from the {111} plane is 15 to 90%, more preferably 30 to 90%, still more preferably 45 to 90%. . If the area ratio is 15% or less, the bendability is not improved because the crystal orientation varies. On the other hand, when the area ratio exceeds 90%, a large amount of distortion is accumulated in the crystal grains due to cold working, so that the bendability is lowered. In the present embodiment, as shown in FIG. 2, the sample coordinate system has a direction parallel to the rolling direction of the titanium copper 1 as [100] (RD direction), perpendicular to [100] and the thickness direction of the titanium copper 1. Is defined as [001] (ND direction) and [010] (TD direction) parallel to the width direction of the titanium copper 1. (The crystal coordinate system defines the a ₁ , a ₂ , and a ₃ axis directions of the Bravais lattice as [100], [010], and [001], respectively).

  As a method of controlling the area ratio of crystal grains having an orientation within 20 ° from the {111} plane, changing the rolling work degree after aging treatment, changing the viscosity of rolling oil during cold rolling It can be performed by changing the rolling load. Specifically, the pole density can be increased by increasing the rolling process, the viscosity of the rolling oil, and the rolling load so that the metal material is easily distorted.

-Characteristics of titanium copper-
The copper alloy which concerns on this embodiment can have the following characteristics in one Embodiment.
(A) The 0.2% proof stress in the rolling parallel direction is 850 MPa or more. (B) The average roughness Ra of the bending surface when performing the Badway W bending test is 2.0 μm or less, preferably 1.0 μm or less. (C) Rolling Elongation in parallel direction is 3% or more (D) Conductivity is 10% IACS or more and 16% IACS or less

The copper alloy which concerns on this embodiment can have the following characteristics in another one Embodiment.
(A) 0.2% proof stress in the rolling parallel direction is 940 MPa or more and 1000 MPa or less. (B) The surface roughness Ra of the bending surface when performing the B-way W bending test is 0.5 μm or more and 0.7 μm or less. (C) Rolling parallel Elongation in direction is 6% or more and 12% or less (D) Conductivity is 10% or more and 16% or less IACS

The copper alloy which concerns on this embodiment can have the following characteristics in another one Embodiment.
(A) 0.2% proof stress in the rolling parallel direction is 1000 MPa or more and 1100 MPa or less. (B) Average roughness Ra of the bending surface when performing the B-way W bending test is 0.5 μm or more and 0.9 μm or less. (C) Rolling parallel. Elongation in direction is 6% to 10.0% (D) Conductivity is 10% IACS to 16% IACS

-Application-
Titanium copper according to this embodiment can be provided as various copper products, for example, plates, strips, foils, tubes, bars and wires. The titanium copper according to the present invention is not limited, but can be suitably used as a material for electronic components such as switches, connectors, jacks, terminals, relays, and batteries.

-Manufacturing method of titanium copper-
Titanium copper according to the present embodiment can be manufactured by performing appropriate heat treatment and cold rolling particularly in the final solution treatment and the subsequent steps. Below, a suitable manufacture example is demonstrated one by one for every process.

1) Ingot production Ingot production by melting and casting is basically performed in a vacuum or in an inert gas atmosphere. If there is any undissolved additive element in dissolution, it may not work effectively for strength improvement. Therefore, in order to eliminate undissolved residue, it is necessary to add a high melting point third element such as Fe or Cr, and after sufficiently stirring, hold for a certain period of time. On the other hand, since Ti is relatively easily dissolved in Cu, it may be added after the third element is dissolved. Therefore, Cu is one or more selected from the group consisting of Mn, Fe, Mg, Co, Ni, Cr, V, Nb, Ag, Be, Misch metal, Mo, Zr, Si, B and P. It is desirable to add a total of 0 to 1.0 mass%, and then add Ti to include 1.0 to 5.0 mass% to produce an ingot.

2) Homogenization annealing and hot rolling Solidification segregation and crystallized material generated during ingot production are coarse, so it is desirable to make it as small as possible by dissolving it in the parent phase as much as possible by homogenization annealing. This is because it is effective in preventing bending cracks. Specifically, after the ingot manufacturing process, it is preferable to perform hot rolling after heating to 900 to 970 ° C. and performing homogenization annealing for 3 to 24 hours. In order to prevent liquid metal embrittlement, the temperature is preferably 960 ° C. or less before and during hot rolling.

3) First solution treatment It is then preferable to perform the solution treatment after appropriately repeating cold rolling and annealing. The reason why the solution treatment is performed in advance is to reduce the burden in the final solution treatment. That is, in the final solution treatment, it is not a heat treatment for dissolving the second phase particles, but is already in solution, so it is only necessary to cause recrystallization while maintaining that state. Just heat treatment. Specifically, the first solution treatment may be performed at a heating temperature of 850 to 900 ° C. for 2 to 10 minutes. In this case, it is preferable to increase the heating rate and the cooling rate as much as possible so that the second phase particles do not precipitate. Note that the first solution treatment may not be performed.

4) Intermediate rolling Since the recrystallized grains in the final solution treatment are generated more uniformly and finely as the degree of processing in the intermediate rolling before the final solution treatment is higher, the degree of processing in the intermediate rolling is set higher. Preferably it is 70 to 99%. The degree of work is defined by {((thickness before rolling−thickness after rolling) / thickness before rolling) × 100%}. In addition, the solution treatment can be performed several times during the intermediate rolling. The solution condition may be about 850 ° C. to 900 ° C. for about 2 to 10 minutes.

5) Final solution treatment In the copper alloy material before the final solution treatment, there are precipitates generated during the casting or intermediate rolling process. Since this precipitate may hinder bendability and increase in mechanical properties after aging, in the final solution treatment, the copper alloy material is heated to a temperature at which the precipitate in the copper alloy material is completely dissolved. It is desirable. However, if the precipitate is heated to a high temperature until it is completely eliminated, the grain boundary pinning effect due to the precipitate disappears, and the crystal grains become coarser rapidly. In addition, the average number density (Y) of the second phase particles becomes extremely small. When crystal grains become coarser, the strength tends to decrease.

  For this reason, as a heating temperature, it heats until the copper alloy raw material before solution forming becomes the solid solution limit vicinity of a 2nd phase particle composition. The temperature at which the solid solubility limit of Ti becomes equal to the addition amount when the addition amount of Ti is in the range of 1.0 to 5.0% by mass (referred to as “solid solubility limit temperature” in the present invention) is about 550 to 1000 ° C. For example, the solid solution temperature of Ti is 600 ° C. when the Ti concentration is 1.0% by mass, 680 ° C. when the Ti concentration is 1.5% by mass, 730 ° C. when the Ti concentration is 2.0% by mass, and the Ti concentration is 3.0% by mass. At 800 ° C., Ti concentration of 4.0% by mass, 840 ° C. and Ti concentration of 5.0% by mass, 885 ° C.

  In this embodiment, the copper alloy material before solution treatment is near the solid solution limit temperature of Ti at 550 to 1000 ° C., more typically 0 to 20 compared to the solid solution limit temperature of Ti at 550 to 1000 ° C. It is preferable to heat until a temperature higher by 0 ° C., preferably a temperature higher by 0 to 15 ° C., more preferably higher by 0 to 10 ° C.

  In order to suppress the generation of coarse second-phase particles in the final solution treatment, it is preferable to heat and cool the copper alloy material as quickly as possible. Specifically, rapid heating can be performed by placing the copper alloy material in an atmosphere that is about 50 to 500 ° C., preferably about 150 to 500 ° C. higher than the temperature near the solid solubility limit of the second phase particle composition. In this case, the copper alloy material is heated at a temperature increase rate of 40 ° C./s or higher, preferably 45 ° C./s or higher after the copper alloy material reaches 200 ° C. Cooling is performed by water cooling or the like. In this case, it is preferable to cool the copper alloy material at a cooling rate of 90 ° C./s or higher, preferably 100 ° C./s or higher, until the Ti alloy material is cooled from the maximum heating temperature to 200 ° C.

  Furthermore, in the final solution treatment according to the present embodiment, the time from heating to cooling, that is, the time from when the copper alloy material reaches a temperature near the solid solution limit temperature of Ti until the start of cooling (= It is preferable to make the holding time as short as possible. In the present embodiment, the holding time is preferably less than 5 seconds, and more preferably 3 seconds or less. By shortening the holding time as much as possible, coarsening of crystal grains can be suppressed. In addition, the average number density (Y) of the second phase particles can be prevented from becoming extremely small.

6) Aging treatment An aging treatment is performed following the final solution treatment. Conventionally, it was customary to perform cold rolling after the final solution treatment, but in order to obtain titanium copper according to the present embodiment, after the final solution treatment, aging treatment is performed immediately without performing cold rolling. It is preferable to carry out. In the conventional process, it was not possible to achieve both bendability and strength. High workability was high strength but poor bendability, and low workability was excellent in bendability but lacked strength. The aging treatment is carried out under aging treatment conditions that provide peak intensity so that fine precipitates of Ti-Cu system are uniformly distributed at appropriate sizes and intervals. Here, the peak intensity is, for example, when the aging treatment time is constant (for example, 10 hours) and the aging treatment temperature is changed (for example, at aging treatment temperatures of 350, 375, 400, 425, 450, 475, and 500 ° C.). The strength when aging treatment is performed under the condition that the strength (tensile strength) is the highest. The aging conditions at this time may be performed at a slightly higher temperature than the aging conditions of the conventional process. Specifically, it is preferable to heat at a material temperature of 350 to 500 ° C. for 0.1 to 20 hours, more preferably to heat at a material temperature of 380 to 480 ° C. for 1 to 16 hours, and 4 at a material temperature of 380 to 480 ° C. It is more preferable to heat for ~ 16 hours. When the aging time is shorter than 4 hours, the average number density (Y) of the second phase particles is small, and the increase in strength after the final cold rolling is small.

7) Final cold rolling (finish rolling)
After the aging treatment, the strength of titanium copper can be increased by performing final cold rolling. When the purpose is to obtain high strength, the degree of processing is 5% or more, preferably 10% or more, more preferably 15% or more. However, if the degree of work is too high, the area ratio of crystal grains having an orientation within 20 ° from the {111} plane increases, and the bendability deteriorates, so the degree of work is 35% or less, preferably 30% or less. More preferably, it is 25% or less. In addition, when the rolling method after aging is made into a condition where distortion is likely to occur, the area ratio of crystal grains having an orientation within 20 ° from the {111} plane of the surface after electrolytic polishing of the rolled surface rapidly increases. In the present embodiment, it is preferable to perform rolling under conditions where the material surface is less likely to be strained even at the same degree of processing.

  For this reason, in this embodiment, the rolling load of the final cold rolling is preferably 115 kg / mm or less per unit length in the width direction of the material, more preferably 100 kg / mm or less. ~ 85 kg / mm. Normally, the final cold rolling is performed at a rolling load of 150 to 200 kg / mm or more in order to industrially roll in a short time. This is because the higher the rolling load, the stronger the force to compress the material in the plate thickness direction, and the material can be reduced to the desired plate thickness in a shorter time. In the present invention, the viscosity of the rolling oil is preferably less than 13 cST, more preferably 10 cST or less, more preferably 7 cST or less, and further preferably 6.8 to 3 cST. Normally, rolling oil having a viscosity of about 7 to 25 cST or higher is generally used for industrial rolling in a short time (for example, 7 to 13 cST in JP 2006-307288 A). is there). As the viscosity of the rolling oil is higher, the optimum lubricating oil thickness can be obtained even at a higher rolling speed, so that the rolling speed can be increased and rolling can be performed in a shorter time.

8) Straightening annealing After the final cold rolling, straightening annealing is performed in order to obtain stress relaxation characteristics necessary for application to electronic components. The conditions for strain relief annealing may be conventional conditions. Specifically, it is preferably performed under the conditions of heating at a material temperature of 200 ° C. or more and less than 550 ° C. for 0.001 to 20 hours. If the material temperature is 200 to 300 ° C. and heated for 12 to 20 hours, and if it is high temperature, it is more preferable to carry out under conditions of a short time (for example, heating at a material temperature of 300 to 400 ° C. for 0.001 to 12 hours). Depending on the required characteristics, this step can be omitted.

  A person skilled in the art will understand that steps such as grinding, polishing, shot blasting, and pickling for removing oxide scale on the surface can be appropriately performed between the above steps.

  Examples of the present invention will be described below together with comparative examples, but these examples are provided for better understanding of the present invention and its advantages, and are not intended to limit the invention.

  When manufacturing the copper alloy of the example, Ti, which is an active metal, is added as the second component, so a vacuum melting furnace was used for melting. In addition, in order to prevent unexpected side effects due to mixing of impurity elements other than the elements defined in the present invention, raw materials having a relatively high purity were carefully selected and used.

  Addition of Ti at the concentration shown in Table 1 and optionally further addition of a third element and heating at 900 to 970 ° C. for 3 hours against the ingot having the composition of the remaining copper and inevitable impurities Thereafter, hot rolling was performed at 900 to 950 ° C. to obtain a hot rolled sheet having a thickness of 10 mm. After descaling by chamfering, it was cold-rolled to obtain a strip thickness (2.0 mm). Next, in the intermediate cold rolling, the intermediate plate thickness was adjusted so that the final plate thickness was 0.10 mm, and cold rolling was performed. Thereafter, it was inserted into an annealing furnace capable of rapid heating and subjected to a final solution treatment. When the copper alloy material reached a predetermined material temperature, it was immediately taken out of the annealing furnace and cooled with water.

  In the final solution treatment, the maximum material temperature of the test piece is a solid solution limit temperature of Ti (about 600 ° C. at a Ti concentration of 1.0% by mass, about 680 ° C. at a Ti concentration of 1.5% by mass, and 2.0% by mass of Ti concentration). Table 1 shows that about 730 ° C., about 800 ° C. at a Ti concentration of 3.0% by mass, about 840 ° C. at a Ti concentration of 4.0% by mass, and about 885 ° C. at a Ti concentration of 5.0% by mass). Heating and cooling were performed at the stated heating rate and cooling rate. In Table 1, “holding time” indicates the time from when the test piece reaches the maximum material temperature to when water cooling starts. “Temperature increase rate” represents an average temperature increase rate from when the test piece reaches 200 ° C. until the maximum temperature of the material is reached. Specifically, (temperature increase rate (° C./s))=((material maximum temperature (° C.) − 200 (° C.)) / (Time required for the specimen to reach the maximum material temperature after reaching 200 ° C.) The “cooling rate” represents the average cooling rate until the specimen is cooled from the maximum material temperature to 200 ° C. Specifically, (cooling rate (° C./s)) = ( (Maximum material temperature (° C.) − 200 (° C.)) / (Time (s) required from the start of water cooling until the temperature of the test piece reaches 200 ° C.) Note that the rate of temperature increase and The standard of the cooling rate was defined as the time until the test piece reached 200 ° C. or until it was cooled to 200 ° C. The driving force of disappearance, generation, and growth of precipitates in the temperature range of 200 ° C. or lower. This is because the diffusion distance of atoms is so small that it can be ignored. After performing an aging treatment at an aging treatment temperature (for example, 400 ° C.) of 3 to 10 hours at which a peak intensity was obtained, finish rolling was performed under the conditions shown in Table 1 to prepare test pieces of Examples and Comparative Examples. In Table 1, “Rolling load per width” indicates the rolling load per unit length in the width direction of the test piece. (Rolling load per unit length in the width direction (kg / mm)) = (Rolling) Load (kg)) / (Sample width (mm))

Characteristic evaluation was performed on the obtained test pieces under the following conditions. The results are shown in Table 2.
<Crystal grain size>
The crystal grain size (average crystal grain size) is measured by exposing the rolled surface to a solution of 67% phosphoric acid + 10% sulfuric acid + water by electrolytic polishing under conditions of 15 V 60 seconds, washing with water and drying for observation. did. The structure was observed using FE-SEM (electrolytic emission scanning electron microscope, manufactured by Philips, XL30SFEG), and the average crystal grain size was determined by the cross line segment method of JIS G0551.
<Number density of second phase particles>
The structure was revealed under the same conditions as the measurement of the crystal grain size, and the grain size and the number of precipitates were measured using FE-SEM. In addition, the fact that either or both of Cu and Ti are included as a component of the precipitate to be measured is analyzed for all precipitates using EDS (energy dispersive X-ray analysis) of FE-SEM. Was confirmed. The number density (Y) and (X) of each was measured by dividing into second phase particles having a particle size of 100 nm or more and 1.0 μm or less and second phase particles having a particle size exceeding 1.0 μm. In this example, calculation is not performed for Ti-Cu-based precipitates (grain boundary reaction phase) (see grain boundary reaction phase 13 in FIG. 1) that precipitate along grain boundaries as grain boundary reaction type particles. did.
<Crystal orientation>
The rolled surface of the test piece was electropolished in a solution of phosphoric acid 67% + sulfuric acid 10% + water under conditions of 15 V 60 seconds to reveal the structure, washed and dried, and then subjected to Ar ion using XPS. Sputtering was performed at 3 kV for 30 seconds for observation. JXA8500F manufactured by JEOL Ltd. was used for EBSP measurement. In the EBSP measurement, as shown in FIG. 3, the rolled surface side surface of the test piece was installed with an inclination of 70 ° with respect to the incident electron beam. An orientation mapping diagram was created using TSL OIM data collection Ver.3.5 as the measurement program and TSL OIM Analysis Ver.3.0 (both manufactured by Tecsem Laboratories) as the analysis program, and the orientation of each crystal grain was determined. The boundary between crystal grains in which the orientation difference between adjacent crystal grains is 15 ° or more was defined as a crystal grain boundary. In Table 2, “area ratio of {111} plane crystal grains when the rolled surface is observed” means crystal grains having an orientation within 20 ° from the {111} plane (displacement from the {111} plane is 20 Was obtained by dividing the area by the area of the field of measurement (ie, “area ratio of {111} plane crystal grains when the rolled surface was observed” = {111} (Area of crystal grains having an orientation within 20 ° from the plane) / (area of measurement visual field) × 100).
<Tensile strength>
A JIS No. 13B specimen was prepared using a press so that the tensile direction was parallel to the rolling direction. The test piece was subjected to a tensile test according to JIS-Z2241, and the breaking strength (tensile strength) in the rolling parallel direction was measured.
<Conductivity>
In accordance with JIS H 0505, the conductivity (EC:% IACS) was measured by a four-terminal method.
<Elongation>
The elongation at break was measured according to JIS-Z2241 for the sample subjected to the tensile test.
<Bending surface>
In accordance with JIS Z 2248, a W bending test was performed with Badway (bending axis being in the same direction as the rolling direction) at R / t = 0, and the bending surface of this test piece was observed. As an observation method, the bending surface was photographed using a laser tech confocal microscope HD100, and the average roughness Ra was measured using the attached software, and compared. In addition, the unevenness | corrugation was not confirmed when the sample surface before a bending process was observed using the confocal microscope. The case where the average surface roughness Ra after bending exceeds 1.0 μm was evaluated as inferior in appearance after bending.

<Discussion>
It can be seen that in all of Examples 1 to 30, the proportion of crystal grains within the range of 20 ° to {111} is within a preferable range.
Examples 1 to 5 show examples in which the final solution treatment is performed at a Ti concentration and a material maximum temperature suitable for the Ti concentration. All examples were good in both tensile strength and elongation.
Examples 6 to 8 show examples when the degree of finish rolling is changed. By reducing the degree of processing, the elongation was improved, and by increasing the degree of processing, the degree of work hardening increased and the strength increased.
Example 9 is Fe as the third element, Example 10 is Co, Example 11 is Cr, Example 12 is Ni, Example 13 is Zr, Example 14 is Mn, Example 15 is Fe, Example 16 is Mg, Example 22 is V, Example 23 is Nb, Example 24 is Mo, Example 25 is Si, Example 26 is B, Example 27 is P, Example 28 is Be, Example 29 is Ag This is an example of adding a single element. Examples 17 to 21 and Example 30 are obtained by adding a plurality of third elements. In any of Examples 9 to 30, the number density (X) and (Y) of the second phase particles were small, and both the tensile strength and the elongation were good.
On the other hand, Comparative Example 1 is an example in the case where the material maximum temperature is not sufficiently increased to the solid solution limit temperature of Ti. In Comparative Example 1, since the solution temperature is lower than the solid solution limit temperature, Ti is not sufficiently dissolved, and the precipitates present before the final solution treatment are coarsened, so the value of number density (X) is increased. The strength and elongation decreased, and the bending surface became rough.
Comparative Example 2 is an example in which the maximum material temperature is set to a temperature that is 200 ° C. higher than the solid solubility limit temperature of Ti. In Comparative Example 2, since the precipitate was sufficiently solid solution at the time of the final solution treatment, the pinning effect by adding Ti was suppressed, the crystal grain size of the base material was increased, the strength was decreased, the bending The surface became rough.
Comparative Examples 3 to 5 are examples in which the holding time, which is the time from when the temperature of the test piece reaches the maximum material temperature to when the water cooling starts, is lengthened. (Comparative example 3 is 10 seconds, comparative example 4 is 40 seconds, comparative example 5 is 70 seconds) By making the holding time longer than that of the example, the crystal grain size was increased and the bending surface was roughened.
In Comparative Examples 6 to 9, the maximum material temperature is about 70 to 100 ° C. higher than the solid solubility temperature of Ti, and the time from when the temperature of the test piece reaches the maximum material temperature until the start of water cooling is the time. This is an example in which the holding time is increased. (Comparative Example 6 is 15 seconds, Comparative Examples 7 and 9 are 20 seconds, and Comparative Example 8 is 25 seconds) By increasing the maximum material temperature compared to the examples and increasing the holding time compared to the examples, the crystal grains The diameter increased and the bending surface became rough.
Comparative Examples 10 and 11 are examples in which the heating rate or cooling rate of the final solution treatment was made slower than that of the example. As shown in Comparative Example 10, since the crystal grain size was increased by slowing the rate of temperature increase to 30 ° C./s, the strength decreased and the bending surface became rough. Further, in Comparative Example 11 in which the cooling rate was slowed down to 70 ° C./s, the ratio of the number density (Y) of the second phase particles increased, so the strength decreased and the bending surface became rough.
In Comparative Example 12, the degree of work hardening during finish rolling was too low at 0.5%, so the degree of work hardening was small and the strength was reduced.
In Comparative Example 13, when the degree of work is too high, 40%, the degree of work hardening is too high, so the strength becomes too high, resulting in poor elongation and a rough bending surface, from {111} to 20 °. The proportion of crystal grains in the range was within.
Comparative Examples 14, 16, 18, and 20 are examples in which the rolling load at the time of finish rolling was increased to 140 to 155 kg / mm, and when observed from the rolling surface, the crystal grains within a range of {111} to 20 ° were observed. Since the ratio increased, the bending surface also became rough.
Comparative Examples 15, 17, 19, and 21 are examples in which the viscosity of the rolling oil was increased to 15 to 18 cST, and crystal grains in the range of {111} to 20 ° when observed from the rolling surface as compared with the examples. Since the ratio of was increased, the bending surface became rough.
In Comparative Example 22, since the amount of Ti is too small, the amount of precipitates is small and the tensile strength is low. In Comparative Example 23, since the amount of Ti is too large, the number density (Y) of second phase particles. The ratio was increased, the strength was low, and the bending surface became rough.
Comparative Examples 24-27 are examples in which the production process was performed in the order of conventional processes, that is, final solution treatment → rolling → aging. In Comparative Examples 24-27, the proportion of crystal grains in the range within 20 ° from {111} was 2% or less when observed from the rolling surface. In Comparative Example 24, the process order of Example 1 was changed, but the elongation was good but the strength was weak. In Comparative Example 25, the degree of work was increased to 45%. As a result, the strength was the same as in Example 1, but the elongation was poor and cracks occurred on the bent surface. Comparative Example 26 is an example in which the holding time from heating to cooling in the final solution treatment is increased to 40 s and the degree of processing is increased to 45% as compared to the example, and the crystal grain size increases and the elongation deteriorates. Cracks occurred on the bending surface. In Comparative Example 27, the holding time was increased to 70 s, but the elongation was good, but the strength was weakened and cracks occurred on the bending surface.
Comparative Examples 28 to 31 were obtained by changing the rolling conditions of Comparative Examples 6 to 9 to a range generally set industrially. However, since the rolling load was large and the viscosity of the rolling oil was high, the rolling conditions were observed from the rolling surface. The ratio of crystal grains within the range of {111} to 20 ° increased (93% or more). For this reason, the bending surface became rougher than Comparative Examples 6-9.

11 Second phase particle 12 Shear band 13 Grain boundary reaction phase 20a-20l Crystal grain having an orientation within 20 ° from {111}

Claims (7)

Titanium copper containing 1.0 to 5.0% by mass of Ti and the balance copper and unavoidable impurities, and in the observation of the structure of the surface after electrolytic polishing of the rolled surface by an electron microscope, the average crystal grain size is 20 μm Hereinafter, the second number of second phase particles having an average number density (X) of 15 × 10 ³ particles / mm ² or less present in the crystal grains and having a particle diameter of 100 nm to 1 μm is greater than or equal to 15 × 10 ³ particles / mm ² . When the average number density (Y) of the phase particles is 3.5 × 10 ³ particles / mm ^{2 to} 35 × 10 ³ particles / mm ² and the surface after electrolytic polishing of the rolled surface is measured by EBSP, {111} Titanium copper in which the proportion of crystal grains within a range of 20 ° is 15 to 90%.   The titanium-copper according to claim 1, which has an elongation of 3.0% or more and a tensile strength of 850 MPa or more.   Titanium copper according to claim 1 or 2, wherein the average roughness Ra of the bending surface is 2.0 µm or less.   One or more selected from the group consisting of Mn, Fe, Mg, Co, Ni, Cr, V, Nb, Mo, Zr, Si, B, Ag, Be, Misch metal and P as the third element group The titanium copper according to any one of claims 1 to 3, wherein 0 to 1.0 mass% in total is contained.   The copper-stretched article which consists of titanium copper of any one of Claims 1-4.   The electronic component which consists of titanium copper of any one of Claims 1-4.   The connector provided with the titanium copper of any one of Claims 1-4.