JP6192552B2 - Titanium copper for electronic parts - Google Patents

Description

  The present invention relates to titanium copper suitable as a member for electronic parts such as a connector.

  In recent years, electronic devices typified by portable terminals and the like have been increasingly miniaturized, and accordingly, connectors used therefor have a tendency of narrow pitch, low profile, and narrow width. The smaller the connector, the narrower the pin width, and the smaller the folded shape, so that the member to be used is required to have high strength to obtain the necessary spring property. 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. As a signal system terminal member, it has been used for a long time.

  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.

When the crystal structure of titanium copper is observed, it is known that a phase different from the parent phase composed of a group of continuously precipitated precipitate particles called “grain boundary reaction phase” appears along the grain boundary. It has been. In the grain boundary reaction phase, it is considered that a lamellar structure in which a copper phase and a Cu ₄ Ti phase as a parent phase are alternately deposited in a stripe shape is formed. FIG. 1 shows an example of a grain boundary reaction phase.

Focusing on the influence of the grain boundary reaction phase on the characteristics of titanium copper, Patent Documents 1 to 3 are listed as techniques for controlling the grain boundary reaction phase. In Patent Document 1 and Patent Document 2, after solution treatment, aging is performed at a high temperature without cold rolling, and the grain boundary reaction phase is increased by not increasing the cooling rate too much. Deterioration is suppressed and high conductivity is achieved. Moreover, since the ductility of the grain boundary reaction phase is higher than that of the stable phase (Cu ₃ Ti or Cu ₄ Ti), it is described that even if the grain size is increased, the strength and bending workability are hardly adversely affected. Patent Document 3 describes that the shape and size of the grain boundary reaction phase are controlled while actively precipitating. The titanium copper described in Patent Document 3 is also subjected to high temperature aging after the solution treatment.

JP 2012-207254 A JP 2012-87343 A International Publication No. 2011-0665152

  As described in Patent Documents 1 to 3, conventionally, there has been a strong recognition that the grain boundary reaction phase is a precipitate that has a positive effect on properties and should be positively precipitated. In addition, it has been recognized that the grain boundary reaction phase is more ductile than the stable phase that precipitates discontinuously. However, according to the examination results of the present inventors, it has been found that the grain boundary reaction phase is a factor for reducing ductility as long as it exists at the grain boundary. In addition, when the grain boundary reaction phase is precipitated, it is considered that Ti dissolved in the solution treatment is not used for spinodal decomposition contributing to strengthening but is used for the grain boundary reaction phase, which also hinders improvement of characteristics. .

  Therefore, an object of the present invention is to obtain an excellent balance between strength and ductility with respect to titanium copper by controlling the grain boundary reaction phase.

  In order to suppress the generation of the grain boundary reaction phase, it is effective to perform heat treatment with a small amount of heat. However, a heat treatment with a small amount of heat causes a problem that spinodal decomposition, which is a strengthening mechanism of titanium copper, does not occur sufficiently. The present inventor, prior to the aging treatment in the state without distortion after the final solution treatment, with respect to the production procedure of titanium copper of the final solution treatment described in Patent Documents 1 to 3 → high temperature aging → cold rolling. It was found that spinodal decomposition, which is a strengthening mechanism of titanium-copper, was promoted by pre-aging at low temperatures, while suppressing the formation of grain boundary reaction phases (continuous precipitates), and strength and ductility. We have succeeded in developing titanium copper with an even better balance. The present invention has been completed against the background of the above findings, and is specified by the following.

In one aspect of the present invention, Ti is contained in an amount of 2.0 to 4.0% by mass, and the third element is Fe, Co, Mg, Si, Ni, Cr, Zr, Mo, V, Nb, Mn, B, and 1-0.5% by mass in total of one or more selected from the group consisting of P, the balance being titanium copper for electronic parts consisting of copper and unavoidable impurities, the structure of the cross section parallel to the rolling direction In the observation, the maximum area ratio occupied by the grain boundary reaction phase in the crystal grains in which the grain boundary reaction phase can be clearly confirmed is 5 to 30%.

  In one embodiment of titanium copper according to the present invention, in the observation of the structure of the cross section parallel to the rolling direction, the number ratio of the crystal grains containing the grain boundary reaction phase is 30 to 80%.

  In another embodiment of the titanium copper according to the present invention, the relationship between 0.2% proof stress (YS; MPa) and elongation (El;%) in the direction parallel to the rolling direction is expressed by the following formula: El ≧ −0. 058 × YS + 65 is satisfied.

  In still another embodiment of the titanium copper according to the present invention, the average crystal grain size in the observation of the structure of the cross section parallel to the rolling direction is 2 to 30 μm.

  In another aspect, the present invention is a copper rolled product including the titanium copper according to the present invention.

  In still another aspect, the present invention is an electronic component including the titanium copper according to the present invention.

  The titanium-copper according to the present invention has an excellent balance between strength and ductility as compared with the prior art. Therefore, the titanium copper according to the present invention is suitable for small electronic devices, and is also suitable for bending and deep drawing.

It is an example of the electron micrograph which caught the grain boundary reaction phase. In the photograph, the part surrounded by the solid line is the grain boundary reaction phase. On the other hand, a stable phase can be seen in a portion surrounded by a dotted line. In the invention example and the comparative example, it is the figure which plotted the relationship between 0.2% yield strength (YS) and elongation (El).

(1) Ti concentration In titanium copper concerning the present invention, Ti concentration shall be 2.0-4.0 mass%. Titanium copper increases strength and electrical conductivity by dissolving Ti in a Cu matrix by solution treatment and dispersing fine precipitates in the alloy by aging treatment.
When the Ti concentration is less than 2.0% by mass, the range of the Ti concentration does not occur or becomes small, and the precipitation of precipitates becomes insufficient, so that a desired strength cannot be obtained. When the Ti concentration exceeds 4.0% by mass, the ductility deteriorates and the material is easily cracked during rolling. Considering the balance between strength and ductility, the preferable Ti concentration is 2.5 to 3.5% by mass.

(2) Third element In the titanium copper according to the present invention, a third element selected from the group consisting of Fe, Co, Mg, Si, Ni, Cr, Zr, Mo, V, Nb, Mn, B, and P. By including one or more elements, the strength can be further improved. However, if the total concentration of the third elements exceeds 0.5% by mass, the ductility deteriorates and the material is easily cracked during rolling. Therefore, these third elements can be contained in a total amount of 0 to 0.5% by mass, and considering the balance between strength and ductility, one or more of the above elements are contained in a total amount of 0.1 to 0.4% by mass. It is preferable to make it.

(3) Maximum erosion rate In one embodiment of the titanium copper according to the present invention, in the observation of the structure of the cross section parallel to the rolling direction, the maximum occupancy of the grain boundary reaction phase in the crystal grains where the grain boundary reaction phase can be clearly confirmed Specifies the area ratio (referred to as “maximum erosion rate”). As the maximum erosion rate increases, ductility and further strength are adversely affected, so it is desirable to suppress this. For example, titanium copper according to the present invention can have a maximum erosion rate of 30% or less, 25% or less, and further 20% or less. On the other hand, if heat treatment is performed with an excessively low calorific value to reduce the maximum erosion rate, the development of spinodal decomposition becomes insufficient, or precipitation of a stable phase occurs, resulting in excellent strength and ductility. Cannot be secured. For example, titanium copper according to the present invention can have a maximum erosion rate of 5% or more, 10% or more, and further 15% or more.

  Considering a balance between strength and ductility, the maximum erosion rate is preferably 8 to 28%, more preferably 10 to 25%.

(4) Precipitated Grain Ratio In one embodiment of titanium copper according to the present invention, the number ratio of crystal grains containing a grain boundary reaction phase (referred to as “precipitated grain ratio”) in the observation of the structure of the cross section parallel to the rolling direction. ). As the precipitation rate increases, the ductility and strength are also adversely affected, so it is desirable to suppress this. For example, the titanium copper according to the present invention can have a precipitation rate of 80% or less, 70% or less, 60% or less, 50% or less, and Can be 40% or less.

  On the other hand, if heat treatment is performed with an excessively low calorie to suppress the rate of precipitated grains, the spinodal decomposition will be insufficiently developed, or stable phase will precipitate, ensuring practical strength and ductility. become unable. For example, the titanium copper according to the present invention can have a precipitation rate of 30% or more, 40% or more, 50% or more, 60% or more, and Can be 70% or more.

  Considering an excellent balance between strength and ductility, the precipitation rate is preferably 40 to 70%, more preferably 45 to 65%.

(5) 0.2% proof stress (YS) and elongation (El)
Titanium copper according to the present invention can achieve both 0.2% proof stress and elongation at a high level.
In one embodiment, the titanium copper according to the present invention is subjected to a tensile test according to JIS-Z2241, and the relationship between 0.2% proof stress (YS; MPa) and elongation (El;%) in a direction parallel to the rolling direction. Satisfies the following formula: El ≧ −0.058 × YS + 65.

  In a preferred embodiment, when the titanium copper according to the present invention is subjected to a tensile test according to JIS-Z2241, the relationship between 0.2% proof stress (YS; MPa) and elongation (El;%) in a direction parallel to the rolling direction. Satisfies the following formula: El ≧ −0.058 × YS + 66.

  In a more preferred embodiment, the titanium copper according to the present invention has a 0.2% proof stress (YS; MPa) and an elongation (El;%) in a direction parallel to the rolling direction when a tensile test according to JIS-Z2241 is performed. The relationship satisfies the following formula: El ≧ −0.058 × YS + 67.

  In a typical embodiment, the titanium copper according to the present invention has a 0.2% proof stress (YS; MPa) and an elongation (El;%) in a direction parallel to the rolling direction when a tensile test according to JIS-Z2241 is performed. Satisfies the following formula: −0.058 × YS + 72 ≧ E1.

  In a more typical embodiment, the titanium copper according to the present invention has a 0.2% proof stress (YS; MPa) and an elongation (El;%) in a direction parallel to the rolling direction when a tensile test according to JIS-Z2241 is performed. ) Satisfies the following formula: −0.058 × YS + 71 ≧ El.

  In a still more typical embodiment, the titanium copper according to the present invention is subjected to a tensile test according to JIS-Z2241, and 0.2% proof stress (YS; MPa) and elongation (El; %) Satisfies the following formula: −0.058 × YS + 70 ≧ El.

  In one embodiment, the titanium copper according to the present invention can have a 0.2% proof stress in a direction parallel to the rolling direction of 900 MPa or more and 950 MPa or more when a tensile test according to JIS-Z2241 is performed. It can be set to 1000 MPa or more, and further can be set to 1050 MPa or more.

  The upper limit value of 0.2% proof stress in the titanium copper according to the present invention is not particularly restricted from the viewpoint of the strength intended by the present invention, but takes time and cost, and increases the Ti concentration to obtain high strength. Therefore, the 0.2% proof stress of the titanium copper according to the present invention is generally 1400 MPa or less, typically 1300 MPa or less, and more typically 1200 MPa or less. Even more typically, it is 1150 MPa or less.

  In one embodiment, the titanium copper according to the present invention can have an elongation (El) in a direction parallel to the rolling direction of 4.5% or more when subjected to a tensile test according to JIS-Z2241, % Or more, 6.0% or more, 7.0% or more, 8.0% or more, 9.0% or more Further, it can be made 10.0% or more. In one embodiment, the titanium-copper according to the present invention can have an elongation (El) in a direction parallel to the rolling direction of 17.0% or less when a tensile test according to JIS-Z2241 is performed. % Or less, 15.0% or less, 14.0% or less, and further 13.0% or less.

(6) Crystal grain size In order to improve the strength and ductility of titanium copper, the smaller the crystal grain, the better. Therefore, the preferable average crystal grain size is 30 μm or less, more preferably 20 μm or less, and still more preferably 10 μm or less. Although there is no particular limitation on the lower limit, ductility tends to deteriorate because it becomes a mixed grain in which non-recrystallized grains exist when attempting to make the crystal grain size more difficult to discriminate. Therefore, the average crystal grain size is preferably 2 μm or more. In the present invention, the average crystal grain size is represented by the equivalent circle diameter in the structure observation of the cross section parallel to the rolling direction by observation with an optical microscope or electron microscope.

(7) Plate thickness of titanium copper In one embodiment of titanium copper according to the present invention, the plate thickness can be 0.5 mm or less, and in a typical embodiment, the thickness is 0.03 to 0.3 mm. In a more typical embodiment, the thickness can be 0.08 to 0.2 mm.

(8) Applications Titanium copper according to the present invention can be processed into various copper products, such as plates, strips, tubes, bars and wires. The titanium-copper according to the present invention can be suitably used as a material for electronic parts such as, but not limited to, connectors, switches, autofocus camera modules, jacks, terminals (for example, battery terminals), and relays.

(9) Manufacturing Method Titanium copper according to the present invention can be manufactured by carrying out 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.

<Ingot manufacturing>
Production of ingots by melting and casting is basically performed in a vacuum or in an inert gas atmosphere. If the additive element remains undissolved during melting, it does not effectively act on 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 stirring sufficiently, hold it for a certain 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 includes one or more selected from the group consisting of Fe, Co, Mg, Si, Ni, Cr, Zr, Mo, V, Nb, Mn, B, and P in total 0 to 0. It is desirable to add it so that it may contain 0.5 mass%, and then to add Ti so that it may contain 2.0-4.0 mass%, and to manufacture an ingot.

<Homogenization annealing and hot rolling>
Since the solidified segregation and crystallized matter produced during the production of the ingot are coarse, 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, it is preferable that the temperature is 960 ° C. or lower before and during hot rolling, and that the pass from the original thickness to 90% of the total rolling reduction is 900 ° C. or higher.

<First solution treatment>
Thereafter, it is preferable to perform the first 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.

<Intermediate rolling>
The higher the rolling reduction in the intermediate rolling before the final solution treatment, the more uniformly and finely control the recrystallized grains in the final solution treatment. Therefore, the rolling reduction of intermediate rolling is preferably 70 to 99%. The rolling reduction is defined by {((thickness before rolling−thickness after rolling) / thickness before rolling) × 100%}.

<Final solution treatment>
In the final solution treatment, it is desirable to completely dissolve the precipitate, but if heated to a high temperature until it completely disappears, the crystal grains are likely to coarsen, so the heating temperature is close to the solid solution limit of the second 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 2.0 to 4.0% by mass is about 730 to 840 ° C., for example, the addition amount of Ti is 3 About 800 ° C. at 0.0 mass%). And if it heats rapidly to this temperature and a cooling rate is also made quick by water cooling etc., generation | occurrence | production of coarse 2nd phase particle | grains will be suppressed. Therefore, it is typically heated to a temperature of −20 ° C. to + 50 ° C. with respect to the temperature at which the solid solubility limit of Ti at 730 to 840 ° C. is the same as the addition amount, and more typically 730 to 840 ° C. Heating is performed at a temperature 0 to 30 ° C higher, preferably 0 to 20 ° C higher than the temperature at which the solid solubility limit of Ti is the same as the addition amount.

  Moreover, the coarsening of a crystal grain can be suppressed when the heating time in the final solution treatment is shorter. The heating time can be, for example, 30 seconds to 10 minutes, and typically 1 minute to 8 minutes. Even if the second phase particles are generated at this point, if they are finely and uniformly dispersed, they are almost harmless to strength and ductility. However, since the coarse particles tend to grow further in the final aging treatment, the second phase particles at this point must be made as small as possible even if they are formed.

<Preliminary aging>
Subsequent to the final solution treatment, a preliminary aging treatment is performed. Conventionally, cold rolling is usually performed after the final solution treatment, but in order to obtain titanium copper according to the present invention, after the final solution treatment, it is immediately preliminarily performed without performing cold rolling. It is important to perform an aging treatment. The pre-aging treatment is a heat treatment performed at a lower temperature than the aging treatment of the next step, and the spinodal decomposition in the parent phase of titanium copper is dramatically accelerated by continuously performing the pre-aging treatment and the aging treatment described later. Is possible. The pre-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 surface oxide film.

  It is difficult to obtain the above advantages even if the heating temperature in the pre-aging treatment is too low or too high. According to the examination results by the present inventors, it is preferable to heat at a material temperature of 150 to 250 ° C. for 10 to 20 hours, more preferably to heat at a material temperature of 160 to 230 ° C. for 10 to 18 hours, and at 170 to 200 ° C. It is even more preferred to heat for 12-16 hours.

<Aging treatment>
An aging process is performed following the preliminary aging process. After the preliminary aging treatment, it may be cooled to room temperature once. Considering the production efficiency, it is desirable that after the preliminary aging treatment, the temperature is raised to the aging treatment temperature without cooling and the aging treatment is continuously performed. There is no difference in the characteristics of titanium copper obtained by any method. However, since the preliminary aging is intended to precipitate the second phase particles uniformly in the subsequent aging treatment, cold rolling should not be performed between the preliminary aging treatment and the aging treatment.

Since titanium dissolved in the solution treatment by the pre-aging treatment is slightly precipitated, the aging treatment should be performed at a slightly lower temperature than the conventional aging treatment, and the material temperature is 0.5 to 0.5 at a material temperature of 300 to 450 ° C. It is preferably heated for -20 hours, more preferably heated at a material temperature of 350-440 ° C. for 2-18 hours, and even more preferably heated at a material temperature of 375-430 ° C. for 3-15 hours. The aging treatment is preferably performed in an inert atmosphere such as Ar, N ₂ and H ₂ for the same reason as the preliminary aging treatment.

<Final cold rolling>
After the aging treatment, the final cold rolling is performed. The strength of titanium copper can be increased by the final cold working, but in order to obtain a good balance between strength and ductility as intended by the present invention, the reduction ratio is 10 to 50%, preferably 20 to 40%. Is desirable.

<Strain relief annealing>
From the viewpoint of improving sag resistance at high temperature exposure, it is desirable to perform strain relief annealing after the final cold rolling. This is because dislocations are rearranged by performing strain relief annealing. The conditions for strain relief annealing may be conventional conditions. However, excessive strain relief annealing is not preferable because coarse particles precipitate and the strength decreases. The strain relief annealing is preferably performed at a material temperature of 200 to 600 ° C. for 10 to 600 seconds, more preferably 250 to 550 ° C. for 10 to 400 seconds, and even more preferably 300 to 500 ° C. for 10 to 200 seconds. .

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

  EXAMPLES Examples (invention examples) of the present invention are shown below together with comparative examples, which are provided for better understanding of the present invention and its advantages, and are not intended to limit the invention. .

  Titanium copper test pieces containing the alloy components shown in Table 1 (Tables 1-1 and 1-2), the balance being copper and inevitable impurities, were produced under various manufacturing conditions, and the structure observation and characteristic evaluation were performed. .

  First, 2.5 kg of electrolytic copper was melted in a vacuum melting furnace, and the third element was added at a blending ratio shown in Table 1, and then Ti at a blending ratio shown in the same table was added. After sufficient consideration was given to the retention time after the addition so that there was no undissolved residue of the added elements, these were injected into the mold in an Ar atmosphere to produce about 2 kg of ingots.

  After the homogenization annealing which heats at 950 degreeC with respect to the said ingot for 3 hours, hot rolling was performed at 900-950 degreeC, and the hot rolled sheet with a plate thickness of 15 mm was obtained. After descaling by chamfering, cold rolling was performed to obtain a strip thickness (2 mm), and a primary solution treatment was performed on the strip. The conditions for the primary solution treatment were heating at 850 ° C. for 10 minutes, and then water cooling. Next, after adjusting the rolling reduction and performing intermediate cold rolling according to the rolling reduction and product sheet thickness conditions in the final cold rolling described in Table 1, it is inserted into an annealing furnace capable of rapid heating. The final solution treatment was performed, followed by water cooling. The heating conditions at this time were such that the material temperature was such that the solid solubility limit of Ti was the same as the addition amount (Ti concentration: 3.0% by mass, about 800 ° C., Ti concentration: 2.0% by mass, about 730 ° C., Ti concentration: 4 0.0 mass% and about 840 ° C.) as a standard. Next, preliminary aging treatment and aging treatment were continuously performed in the Ar atmosphere under the conditions described in Table 1. Here, no cooling was performed after the preliminary aging treatment. After descaling by pickling, final cold rolling was performed under the conditions described in Table 1, and finally, strain relief annealing was performed under each heating condition described in Table 1 to obtain test pieces of invention examples and comparative examples. Depending on the specimen, preliminary aging treatment, aging treatment or strain relief annealing was omitted.

The following evaluation was performed about the produced product sample.
(A) 0.2% yield strength (YS)
A JIS No. 13B test piece was prepared, and 0.2% proof stress in a direction parallel to the rolling direction was measured using a tensile tester according to JIS-Z2241.
(B) Elongation (El)
A tensile test was performed under the same conditions as the measurement of 0.2% proof stress, and the elongation (%) at the breaking point was measured.
(C) Average crystal grain size The average crystal grain size of each product sample was measured by cutting the rolled surface with FIB to expose a cross section parallel to the rolling direction, and then using an electron microscope (XL30 manufactured by Philips). SFEG) was observed at a magnification of 1000 times, the number of crystal grains per unit area was counted, and the average equivalent circle diameter of the crystal grains was determined. Specifically, a frame of 100 μm × 100 μm was created, and the number of crystal grains present in this frame was counted. Note that all the crystal grains crossing the frame were counted as ½. The average value of the area per crystal grain is obtained by dividing the frame area of 10,000 μm ² by the total. Since the diameter of the true circle having the area is the equivalent circle diameter, an average value of equivalent circle diameters for any five observation visual fields was obtained, and this was used as the average crystal grain size.
(D) Precipitation grain ratio In the same manner as the average grain size, any 200 crystal grains can be observed from a cross section parallel to the rolling direction, and the grain boundary reaction phase can be clearly confirmed (specifically, The ratio of those having a grain boundary reaction phase in which the maximum width in the direction perpendicular to the tangent to the grain boundary grew to 0.5 μm or more was calculated.
(E) Maximum erosion rate In the same manner as the average crystal grain size, arbitrary 200 crystal grains are observed from a cross section parallel to the rolling direction, and the grain boundary reaction phase can be confirmed for the grain boundary reaction phase. The area ratio occupied by each was calculated, and the maximum value was taken as the maximum erosion rate. To calculate the area ratio of the grain boundary reaction phase for the crystal grain, select individual crystal grains including the grain boundary reaction phase, and perform image analysis to determine the total area and the area of only the grain boundary reaction phase (one crystal grain In the case where a plurality of grain boundary reaction phases exist therein, the total area) was calculated.

(Discussion)
Table 1 (Tables 1-1 and 1-2) shows the test results. In Invention Example 1, since the conditions of final solution treatment, preliminary aging, aging, and final cold rolling were appropriate, spinodal decomposition was promoted while the development of the grain boundary reaction phase was suppressed, and 0.2. It can be seen that the coexistence in the dimension with high% yield strength and ductility is achieved.
Inventive Example 2 was able to ensure good 0.2% proof stress and ductility although spinodal decomposition and grain boundary reaction phase were suppressed by lowering the pre-aging heating temperature than Inventive Example 1.
Inventive Example 3 made the pre-aging heating temperature higher than Inventive Example 1 to further accelerate the spinodal decomposition and develop a grain boundary reaction phase, but still could ensure good 0.2% yield strength and ductility.
Inventive Example 4 was able to ensure good 0.2% proof stress and ductility, although spinodal decomposition and grain boundary reaction phase were suppressed by lowering the aging heating temperature than Inventive Example 1.
In invention example 5, spinodal decomposition was further promoted by raising the aging heating temperature higher than in invention example 1 and a grain boundary reaction phase was developed, but still good 0.2% proof stress and ductility could be secured.
Inventive Example 6 was able to ensure good 0.2% proof stress and ductility, although spinodal decomposition and grain boundary reaction phase were suppressed by making the rolling reduction in the final cold rolling smaller than Inventive Example 1.
Inventive Example 7 further increased spinodal decomposition by increasing the reduction ratio in the final cold rolling as compared with Inventive Example 1, and developed a grain boundary reaction phase, but still could ensure good 0.2% yield strength and ductility. It was.
In invention example 8, although the stress relief annealing was omitted with respect to invention example 1, good 0.2% proof stress and ductility could still be secured.
In Invention Example 9, the heating temperature in strain relief annealing was higher than that in Invention Example 1, but still good 0.2% proof stress and ductility could be secured.
Reference Example 10 is an example in which the heating temperature in preliminary aging, aging, and strain relief annealing is shifted to the high temperature side with respect to Invention Example 1. Although 0.2% proof stress fell compared with invention example 1, favorable 0.2% proof stress and ductility were still securable.
Invention Example 11 is an example in which the Ti concentration in titanium copper was lowered to the lower limit compared to Invention Example 1. Although spinodal decomposition was suppressed and the strength was reduced, good 0.2% proof stress and ductility were still secured.
Invention Example 12 is an example in which the Ti concentration in titanium copper was increased to the upper limit compared to Invention Example 1. Although spinodal decomposition was further promoted and a grain boundary reaction phase was developed, good 0.2% proof stress and ductility could still be secured.
Inventive Examples 13 to 18 are examples in which the third element was variously added to Inventive Example 1, but still good 0.2% proof stress and ductility could be secured.
In Comparative Example 1, the final solution treatment temperature was too low, resulting in mixed grains in which the non-recrystallized region and the recrystallized region were mixed. Moreover, the grain boundary reaction phase could not be observed.
In Comparative Example 2, since no pre-aging treatment was performed, the grain boundary reaction phase developed excessively and the ductility was poor.
Comparative Example 3 roughly corresponds to the titanium copper of Invention Example 1 described in JP2012-207254A. Since the preliminary aging treatment was not performed and the aging treatment was performed at a high temperature, the grain boundary reaction phase developed excessively and the ductility was poor.
Comparative Example 4 roughly corresponds to titanium copper of Invention Example 17 described in JP2012-207254A. The preliminary aging treatment was not carried out, the aging treatment was carried out at a high temperature, and further the strain relief annealing was carried out, so that the grain boundary reaction phase developed excessively and the balance between strength and ductility was poor.
Comparative Example 5 roughly corresponds to titanium copper of Comparative Example 6 described in JP2012-207254A. When the preliminary aging treatment was not performed and the aging treatment was performed at a high temperature, the ductility was high but the strength was remarkably low.
Comparative Example 6 roughly corresponds to titanium copper of Comparative Example 3 described in International Publication No. 2011/066512. Although the solution treatment was performed at a high temperature, but the pre-aging treatment was not performed, the grain boundary reaction phase developed excessively and the ductility was poor.
Comparative Example 7 roughly corresponds to the titanium-copper of Comparative Example 4 described in International Publication No. 2011/066512. By performing the solution treatment at a low temperature and omitting the preliminary aging treatment, the recovery was insufficient due to the lack of solution treatment, and the ductility was insufficient.
In Comparative Example 8, although the preliminary aging treatment was performed, the heating temperature was too low, so the effect of suppressing the grain boundary reaction phase was insufficient, and the ductility was poor.
In Comparative Example 9, since the heating temperature in the preliminary aging was too high, the strength was lowered due to overaging, and further, a grain boundary reaction phase was developed and the ductility was poor.
In Comparative Example 10, a large amount of stable phase precipitated after preliminary aging because no aging treatment was performed. Therefore, the 0.2% proof stress was reduced with respect to Invention Example 1.
Comparative Example 11 is a case where it can be evaluated that the final solution treatment → cold rolling → aging treatment was performed. The stable phase developed and the 0.2% yield strength decreased.
In Comparative Example 12, since the aging heating temperature was too low, a large number of stable phases were precipitated, and the 0.2% proof stress was lowered with respect to Invention Example 1.
In Comparative Example 13, since the aging heating temperature was too high, it was overaged and the grain boundary reaction phase was excessively developed. Therefore, the 0.2% proof stress was reduced with respect to Invention Example 1.
In Comparative Example 14, since the amount of the third element added was too large, cracking occurred during hot rolling, so that a test piece could not be produced.
In Comparative Example 15, the spinodal decomposition was insufficient because the Ti concentration was too low, and the strength was insufficient with respect to Invention Example 1.
In Comparative Example 16, since the Ti concentration was too high, cracking occurred during hot rolling, and thus the test piece could not be produced.

Claims (4)

It contains 2.0 to 4.0% by mass of Ti, and is selected from the group consisting of Fe, Co, Mg, Si, Ni, Cr, Zr, Mo, V, Nb, Mn, B, and P as the third element. In addition, in the observation of the structure of the cross section parallel to the rolling direction, the grain boundary reaction phase is a titanium-copper for electronic parts comprising at least one kind in total of 0 to 0.5% by mass with the balance being copper and inevitable impurities. Can be clearly confirmed , the maximum area ratio of the grain boundary reaction phase in the crystal grains is 5 to 30%, the number ratio of the crystal grains containing the grain boundary reaction phase is 30 to 80%, and the average crystal grain size is 2 Titanium copper which is ˜30 μm.   2. The titanium-copper according to claim 1, wherein the relationship between 0.2% proof stress (YS; MPa) and elongation (E1;%) in a direction parallel to the rolling direction satisfies the following formula: El ≧ −0.058 × YS + 65.   A rolled copper product comprising the titanium-copper according to claim 1 or 2.   The electronic component provided with the titanium copper of Claim 1 or 2.