JP6151637B2 - 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. 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 cold rolling reduction ratio, the more dislocations introduced and the higher the dislocation density, so that the number of nucleation sites contributing to precipitation increases and the strength after aging treatment can be increased. 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), refining crystal grains (Patent Document 4), controlling crystal orientation (Patent Document 5), etc., a technique for achieving both the strength and bending workability of titanium copper is proposed. Has been.

  Further, in Patent Document 6, as the titanium modulation structure due to spinodal decomposition develops, the fluctuation of the titanium concentration increases, thereby giving the titanium copper stickiness and improving the strength and bending workability. Have been described. Therefore, Patent Document 6 proposes a technique for controlling fluctuations in Ti concentration in the matrix due to spinodal decomposition. In Patent Document 6, a heat treatment (sub-aging treatment) is performed after the final solution treatment, spinodal decomposition is caused in advance, and then cold rolling at a conventional level, aging treatment at a conventional level, or a temperature lower and shorter than that. It is described that the Ti concentration fluctuation is increased by increasing the Ti concentration by performing the aging treatment.

Japanese Patent Laid-Open No. 2004-231985 JP 2004-176163 A JP-A-2005-97638 JP 2006-265611 A JP 2012-188680 A JP 2012-097306 A

  As described above, in the past, many efforts have been made to improve the characteristics in terms of both strength and bending workability. However, downsizing of electronic parts such as connectors mounted due to downsizing of electronic devices has further progressed. . In order to follow such a technological trend, it is necessary to achieve the strength and bending workability of titanium copper at a higher level. It has been shown that increasing the fluctuation of Ti concentration due to spinodal decomposition is effective for improving the balance between strength and bending workability, but there is still room for improvement.

  Accordingly, an object of the present invention is to control the fluctuation of Ti concentration in titanium copper from a viewpoint different from the conventional one and improve the strength and bending workability.

  The present inventor found that the Ti concentration fluctuation curve obtained by EDX line analysis of the Ti concentration in the matrix of titanium copper is the slope when connecting the peaks of the adjacent peaks and the valleys of the valleys with a straight line. It was found that the absolute value of, and the Ti concentration difference between the top of the adjacent peak and the bottom of the valley significantly affected the strength and bending workability. And it discovered that the balance of these characteristics could be improved by controlling the said inclination appropriately. 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 One or more selected from the group consisting of P is contained in a total of 0 to 0.5% by mass, and the balance is titanium copper for electronic parts made of copper and inevitable impurities, in a cross section parallel to the rolling direction. In the Ti concentration fluctuation curve obtained by line analysis of Ti in the matrix with EDX for crystal grains with 100> orientation, the absolute value of the slope when connecting the peaks of adjacent peaks and valleys with a straight line The number of second phase particles having an average of 0.30 to 1.00% by mass / nm and a size of 3 μm or more in the structure observation of the cross section parallel to the rolling direction per observation field of 10,000 μm ² is 35 It is titanium copper which is the following.

  In another embodiment of the titanium copper according to the present invention, in the Ti concentration fluctuation curve, the average of the Ti concentration difference between the peak of the adjacent peak and the bottom of the valley is 2.5 to 15.0% by mass. is there.

  In 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 yet another embodiment of the titanium-copper according to the present invention, the 0.2% yield strength in the direction parallel to the rolling direction is 900 MPa or more, and the plate width (w) / plate thickness (t) = 3. When the W-bending test of Badway (the bending axis is the same direction as the rolling direction) is performed with a bending width of 0.0 and a bending radius (R) / plate thickness (t) = 0, no crack is generated in the bent portion.

  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.

  According to the present invention, titanium copper having an improved balance between strength and bending workability can be obtained. By using titanium copper according to the present invention as a material, an electronic component such as a highly reliable connector can be obtained.

FIG. 1 is an example of a fluctuation curve of Ti concentration obtained when line analysis of Ti in the matrix of titanium copper according to the present invention is performed by EDX. FIG. 2 is a partially enlarged view of FIG. FIG. 3 is an example of a mapping image of Ti in the parent phase of titanium copper.

(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, fluctuations in the Ti concentration do not occur or become small, and precipitation of precipitates becomes insufficient, so that a desired strength cannot be obtained. When the Ti concentration exceeds 4.0% by mass, bending workability deteriorates and the material is easily cracked during rolling. Considering the balance between strength and bending workability, 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 bending workability 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 bending workability, the total amount of one or more of the above elements is 0.1 to 0.4% by mass. % Content is preferable.

(3) In the Ti concentration fluctuation curve, the absolute value of the slope when the peaks of adjacent peaks and valleys are connected by a straight line, and the Ti concentration difference between the peaks of adjacent peaks and valleys of the valley , The horizontal axis is distance (nm) and the vertical axis is Ti concentration (mass%) by line analysis of Ti in the parent phase by EDX for crystal grains with <100> orientation in the cross section parallel to the rolling direction. A Ti concentration fluctuation curve is drawn, and the average of the absolute values of the slopes when the peaks of adjacent peaks and valleys are connected by a straight line is obtained. Specifically, the Ti concentration is analyzed by energy dispersive X-ray spectroscopy (EDX) using a scanning transmission electron microscope (STEM) with respect to a cross section parallel to the rolling direction (STEM-EDX analysis). When the parent phase is line-analyzed for the crystal grains of <100> orientation of titanium copper by STEM-EDX analysis, a fluctuation curve in which the Ti concentration periodically changes can be drawn as shown in FIG. The average line shown in FIG. 1 represents a value (average value) obtained by dividing the total value of Ti concentration (mass%) at each measurement point measured by line analysis by the number of measurement points.
FIG. 2 shows an example of an enlarged view of the Ti concentration fluctuation curve. In the fluctuation curve of Ti concentration, assuming that a portion protruding above the average line is a peak and a portion protruding below is a valley, each peak has a peak, and each valley has a valley bottom. The dotted line in FIG. 2 shows the inclination when connecting the top of the adjacent mountain and the bottom of the valley with a straight line. In the case of the curve in FIG. 2, as shown in Table 1, the absolute value of each slope and the Ti concentration difference between the peak of the adjacent peak and the valley bottom can be obtained.

  The measurement distance for line analysis is 150 nm or more from the viewpoint of preventing measurement errors. The same analysis is repeated 5 times in different observation fields, and the average value thereof is taken as the measurement value. In line analysis, the fluctuation state of Ti concentration varies greatly depending on the direction of analysis. This is because the Ti concentration parts are regularly arranged at intervals of several tens of nm. Therefore, before performing line analysis, Ti mapping is performed in advance, and line analysis is performed aiming at a region where the density of Ti increases. As shown in FIG. 3, it is preferable to perform line analysis in the direction of the arrow (solid line) from the mapping of Ti. Further, when line analysis is performed in the direction of the arrow (dotted line), the density of Ti becomes light, which is not preferable.

  In the present invention, one of the features is that the average of the absolute values of the slopes when the peaks of the adjacent peaks and the valleys of the valleys are connected by a straight line in the Ti concentration fluctuation curve is large. As a result, it is considered that the titanium copper is given a stickiness and the strength and bending workability are improved. In one embodiment of titanium copper according to the present invention, the average absolute value of the slope is 0.30 mass% / nm or more, 0.40 mass% / nm or more, more preferably 0.50 mass. % / Nm or more, still more preferably 0.60 mass% / nm or more.

  However, if the average of the absolute values of the inclination becomes too large, coarse second-phase particles are likely to precipitate, and conversely, the strength and bending workability tend to decrease. Therefore, in one embodiment of titanium copper according to the present invention, the average absolute value of the inclination is 1.00% by mass / nm or less, preferably 0.90% by mass / nm or less, more preferably It is 0.80 mass% / nm or less, More preferably, it is 0.75 mass% / nm or less.

  In the Ti concentration fluctuation curve, the average of the Ti concentration difference between the top of the adjacent peak and the bottom of the valley has a slight correlation with the average of the absolute value of the slope, and the average of the absolute value of the slope becomes large. Along with this, the average of the Ti concentration difference tends to increase. However, by appropriately controlling not only the average of the absolute value of the slope but also the average of the Ti concentration difference, further improvement in the balance between strength and bending workability can be expected. Considering the balance between strength and bending workability, the average Ti concentration difference is preferably 2.5% by mass or more, more preferably 3.0% by mass or more, and 4.0% by mass or more. Even more preferably. Moreover, the average of the Ti concentration difference is preferably 15.0% by mass or less, more preferably 13.0% by mass or less, and still more preferably 11.0% by mass or less.

(4) Second-phase particles The titanium-copper according to the present invention also has a feature that there are few coarse second-phase particles despite the large inclination described above in the Ti concentration fluctuation curve. Since coarse second-phase particles have an adverse effect on strength and bending workability, it is preferable to control, coupled with the effect of improving characteristics by optimizing the inclination, the strength and bending workability are remarkably excellent. Titanium copper is obtained. In the present invention, the second phase particles are a crystallized product generated in the solidification process of melt casting, a precipitate generated in the subsequent cooling process, a precipitate generated in the cooling process after hot rolling, and a cooling process after solution treatment. And a precipitate generated in the aging treatment process, and typically has a Cu-Ti-based composition. The size of the second phase particles is defined as the diameter of the maximum circle that can be surrounded by precipitates when the cross section parallel to the rolling direction is observed with an electron microscope.

In one embodiment of titanium copper according to the present invention, the number of second phase particles having a size of 3 μm or more per observation visual field of 10,000 μm ² is 35 or less. The number of second phase particles having a size of 3 μm or more per observation visual field of 10,000 μm ² is preferably 30 or less, more preferably 25 or less, and even more preferably 20 or less, 15 It is even more preferable that the number is 10 or less, and it is even more preferable that the number is 10 or less. The number of second-phase particles having a size of 3 μm or more per observation field of 10,000 μm ² is preferably 0, but it is difficult to keep the absolute values of the slopes of peaks and valleys within a specified range. One or more, typically three or more.

(5) 0.2% yield strength and bending workability In one embodiment, the titanium copper according to the present invention has a 0.2% yield strength in a direction parallel to the rolling direction of 900 MPa when a tensile test according to JIS-Z2241 is performed. It is the above, and it is set as bending width (w) / sheet thickness (t) = 3.0, bending radius (R) / sheet thickness (t) = 0, Badway (bending axis is the same direction as a rolling direction) When the W-bending test of) is carried out according to JIS-H3130, no crack is generated in the bent portion.

  In a preferred embodiment, the titanium copper according to the present invention has a 0.2% proof stress in a direction parallel to the rolling direction of 1000 MPa or more when subjected to a tensile test according to JIS-Z2241, and a sheet width (w). / Wave bending test with bending width (t) = 3.0 and bending radius (R) / sheet thickness (t) = 0 and Badway (bending axis is in the same direction as the rolling direction) was performed according to JIS-H3130. When this occurs, cracks do not occur in the bent part.

  In a more preferred embodiment, the titanium copper according to the present invention has a 0.2% proof stress in a direction parallel to the rolling direction of 1050 MPa or more when subjected to a tensile test according to JIS-Z2241, and a sheet width (w ) / Plate thickness (t) = 3.0, bending radius (R) / plate thickness (t) = 0, and Badway (bending axis is in the same direction as the rolling direction) W bending test according to JIS-H3130 When implemented, no cracks are produced in the bent part.

  In an even more preferred embodiment, the titanium copper according to the present invention has a 0.2% proof stress in a direction parallel to the rolling direction of 1100 MPa or more when subjected to a tensile test according to JIS-Z2241, and a sheet width ( w) / Bet thickness (t) = 3.0 and bending radius (R) / plate thickness (t) = 0, Badway (bending axis is in the same direction as the rolling direction) W bending test is JIS-H3130 When it is carried out according to the above, no cracks are generated in the bent part.

  The upper limit of 0.2% proof stress is not particularly restricted in terms of the intended strength of the present invention, but it takes time and effort, and there is a risk of cracking during hot rolling if the Ti concentration is increased 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.

(6) Crystal grain size In order to improve the strength and bending workability 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. There is no particular limitation on the lower limit, but if it is attempted to make the crystal grain size more difficult, it becomes a mixed grain in which non-recrystallized grains exist, and the bending workability tends to deteriorate. 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. In particular, the heat treatment after the final solution treatment may be made in two stages with respect to the titanium copper manufacturing procedure of final solution treatment described in Patent Document 6 → heat treatment (sub-aging treatment) → cold rolling → aging treatment. It is valid. 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 bending workability. 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 by continuously performing the pre-aging treatment and the aging treatment described later, in the Ti concentration fluctuation curve while suppressing the generation of coarse precipitates. It is possible to dramatically increase the absolute value of the slope when connecting the peaks of adjacent peaks and valleys with straight lines. 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 Ti dissolved in the solution treatment by the pre-aging treatment is slightly precipitated, the aging treatment should be carried out 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. Although the strength of titanium copper can be increased by the final cold working, in order to obtain a good balance between high strength and bending workability as intended by the present invention, the reduction ratio is 10 to 50%, preferably 20 It is desirable to set it to -40%.

<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 2 (Tables 2-1 and 2-2), the balance being copper and inevitable impurities, were prepared under various manufacturing conditions, and Ti in each matrix was changed to Ti. In the Ti concentration fluctuation curve obtained when line analysis is performed by EDX, the average of the absolute values of the slopes when connecting the peaks of the adjacent peaks and the valleys with straight lines, and the peaks and valleys of the adjacent peaks The average Ti concentration difference at the bottom of the valley and the 0.2% proof stress and bending workability were investigated.

  First, 2.5 kg of electrolytic copper was melted in a vacuum melting furnace, the third element was added at a blending ratio shown in Table 2, 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 according to the conditions of the rolling reduction and product sheet thickness in the final cold rolling described in Table 2 and performing the intermediate cold rolling, 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 (Approx. 840 ° C. at 0.0 mass%). Next, preliminary aging treatment and aging treatment were continuously performed in the Ar atmosphere under the conditions described in Table 2. 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 2, and finally, strain relief annealing was performed under each heating condition described in Table 2 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.
(Ii) 0.2% yield strength A JIS No. 13B test piece was prepared, and 0.2% yield strength in a direction parallel to the rolling direction was measured using a tensile tester according to JIS-Z2241.
(B) Bending workability W-bending test of Badway (bending axis is the same direction as the rolling direction) with a bending width of plate width (w) / plate thickness (t) = 3.0 according to JIS-H3130, cracking The minimum bend radius ratio (MBR / t), which is the ratio of the minimum bend radius (MBR) and thickness (t) at which no occurrence occurs, was determined. At this time, the presence or absence of cracks was judged by whether or not a crack was generated in the bent portion by finishing the cross section of the bent portion to a mirror surface by mechanical polishing and observing with an optical microscope.
(C) STEM-EDX analysis About each test piece, the rolling surface was cut | disconnected by the focused ion beam (FIB), the cross section parallel to a rolling direction was exposed, and the sample thickness was processed thinly to about 100 nm or less. Then, the <100> orientation grain was specified by EBSD, and the inside of the mother phase of the crystal grain was observed. The reason for observing crystal grains with <100> orientation is that the density of Ti concentration is the most dense. The observation is performed using a scanning transmission electron microscope (JEOL Ltd., model: JEM-2100F), and the detector is an energy dispersive X-ray analyzer (EDX, manufactured by JEOL Ltd., model: JED-2300). The measurement was performed at an inclination angle of 0 °, an acceleration voltage of 200 kV, and an electron beam spot diameter of 0.2 nm. Then, the EDX line analysis was performed by setting the measurement distance of the mother phase to 150 nm, the number of measurement points per 150 nm of the measurement distance of the mother phase: 150, and the interval between the measurement points of the mother phase: 1 nm. In order to prevent measurement errors due to the influence of the second phase particles, the measurement position of the parent phase was selected as an arbitrary position where the second phase particles do not exist. As for the direction of line analysis, Ti was mapped in advance, and the direction in which the density of Ti concentration was increased was selected following the solid line in FIG.
From the obtained Ti concentration fluctuation curve, in accordance with the method described above, the average of the absolute values of the slopes when connecting the peaks of the adjacent peaks and the valleys of the valleys with a straight line (in Table 2, “slope of peaks and valleys”). And the average Ti concentration difference between the tops of the adjacent peaks and the bottom of the valleys (“Difference between peaks and valleys” in Table 2).

(D) Crystal grain size In addition, 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 observing the cross section with an electron microscope (manufactured by Philips). XL30 SFEG), 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 perfect circle having the area is the equivalent circle diameter, this was defined as the average crystal grain size.
(E) Number density of coarse second-phase particles After the rolled surface of each product sample is cut with FIB to expose a cross section parallel to the rolling direction, the cross section is used with an electron microscope (Philips XL30 SFEG). According to the definition described above, the number of second phase particles each having a size of 3 μm or more present in an area of 10,000 μm ² was counted, and the average of any 10 locations was determined.

(Discussion)
Table 2 (Tables 2-1 and 2-2) shows the test results. In Invention Example 1, since the conditions of final solution treatment, preliminary aging, aging, and final cold rolling were appropriate, the absolute values of the slopes of peaks and valleys increased, while coarse second-phase particles It can be seen that a balance of 0.2% proof stress and high bending workability is achieved.
Inventive Example 2 made the absolute value of the slope of the peaks and valleys smaller by lowering the heating temperature for preliminary aging than in Inventive Example 1. Although the 0.2% proof stress was lower than that of Invention Example 1, a satisfactory 0.2% proof stress and bending workability could still be secured.
In Invention Example 3, the absolute value of the slopes of the peaks and troughs was increased by increasing the pre-aging heating temperature higher than in Invention Example 1. Although the 0.2% proof stress was lower than that of Invention Example 1, the good balance of 0.2% proof stress and bending workability could still be maintained.
Inventive Example 4 had a lower aging heating temperature than Inventive Example 1, so that the absolute values of the slopes of the peaks and valleys became smaller. Although the 0.2% proof stress was lower than that of Invention Example 1, a satisfactory 0.2% proof stress and bending workability could still be secured.
In invention example 5, the aging heating temperature was made higher than in invention example 1, so that the absolute values of the slopes of the peaks and valleys were increased. Although the 0.2% proof stress was lower than that of Invention Example 1, a satisfactory 0.2% proof stress and bending workability could still be secured.
Inventive Example 6 had a reduction ratio in the final cold rolling smaller than Inventive Example 1, so that the absolute values of the slopes of the peaks and valleys were reduced, and the 0.2% proof stress was lower than Inventive Example 1, but still good. 0.2% proof stress and bending workability could be secured.
Invention Example 7 improved the 0.2% proof stress while maintaining high bending workability by making the rolling reduction in the final cold rolling higher than Invention Example 1.
In invention example 8, although the stress relief annealing was omitted with respect to invention example 1, good 0.2% proof stress and bending workability could still be secured.
In Invention Example 9, the heating temperature in strain relief annealing was higher than that in Invention Example 1, but good 0.2% proof stress and bending workability could still be secured.
In Invention Example 10, the heating temperature in preliminary aging, aging, and strain relief annealing was higher than that in Invention Example 1, so that the absolute value of the slope of the peak and valley and the concentration difference between the peak and valley increased. Although the density difference between the peaks and valleys deviated from the specified range, the 0.2% proof stress was inferior to that of Invention Example 1, but the satisfactory 0.2% proof stress and bending workability could still be secured.
Invention Example 11 is an example in which the third element is omitted from Invention Example 1 and the Ti concentration is lowered to the lower limit. Although the absolute values of the slopes of the peaks and valleys decreased and the 0.2% yield strength decreased, good 0.2% yield strength and bending workability could still be secured.
Inventive Example 12 omits the third element from Inventive Example 1 and increases the Ti concentration in the titanium copper to the upper limit, thereby increasing the absolute values of the slopes of the peaks and valleys. Although the 0.2% proof stress was lower than that of Invention Example 1, a satisfactory 0.2% proof stress and bending workability could still be secured.
Inventive Examples 13 to 18 are examples in which a third element different from that of Inventive Example 1 was added, but good 0.2% proof stress and bending workability could still be secured.
In Comparative Example 1, since the final solution treatment temperature was too low, mixing of unrecrystallized regions and recrystallized regions occurred, and the absolute values of the slopes of peaks and valleys were reduced. Therefore, bending workability was bad.
In Comparative Example 2, since the preliminary aging treatment was not performed, the absolute values of the slopes of the peaks and valleys were small, and the bending workability was poor.
Comparative Examples 3 to 4 correspond to titanium copper described in Patent Document 6. Since the preliminary aging treatment and the aging treatment were not performed continuously, the absolute values of the slopes of the peaks and valleys were reduced, and the bending workability was poor.
In Comparative Example 5, although the pre-aging treatment was performed, the heating temperature was too low, so the absolute values of the slopes of the peaks and valleys were not sufficiently large, and the bending workability was poor.
In Comparative Example 6, since the heating temperature in the preliminary aging was too high, the absolute value of the slopes of the peaks and valleys was excessively large, and some stable phases were precipitated as coarse particles, resulting in a decrease in bending workability. did.
In Comparative Example 7, since no aging treatment was performed, spinodal decomposition was insufficient, and the absolute values of the slopes of the peaks and valleys were reduced. Therefore, 0.2% proof stress and bending workability were reduced with respect to Invention Example 1.
Comparative Example 8 is a case where it can be evaluated that the final solution treatment → cold rolling → aging treatment was performed. The absolute values of the slopes of the peaks and valleys were reduced, and 0.2% proof stress and bending workability were reduced as compared with Invention Example 1.
In Comparative Example 9, since the aging heating temperature was too low, the absolute values of the slopes of the peaks and valleys were reduced, and 0.2% proof stress and bending workability were reduced as compared with Invention Example 1.
In Comparative Example 10, since the aging heating temperature was too high, a part of the stable phase was precipitated as coarse particles. Therefore, 0.2% proof stress and bending workability were reduced with respect to Invention Example 1.
In Comparative Example 11, since the heating temperature for strain relief annealing was too high, some stable phases were precipitated as coarse particles. Therefore, 0.2% proof stress and bending workability were reduced with respect to Invention Example 1.
Comparative Example 12 is an example in which only the aging treatment was performed after the final solution treatment, but a large number of coarse second phase particles were precipitated. Therefore, 0.2% proof stress and bending workability were reduced with respect to Invention Example 1.
In Comparative Example 13, since the amount of the third element added was too large, cracking occurred during hot rolling, and thus the test piece could not be manufactured.
In Comparative Example 14, since the Ti concentration was too low, the absolute values of the slopes of the peaks and valleys were reduced, resulting in insufficient strength and bending workability.
In Comparative Example 15, because 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, it is a titanium copper for electronic parts that contains 0 to 0.5% by mass in total with the balance being copper and unavoidable impurities, and the crystal grains of <100> orientation in the cross section parallel to the rolling direction In the Ti concentration fluctuation curve obtained when line analysis of Ti in the matrix phase is performed by STEM- EDX, the average of the absolute values of the slopes when the peaks of adjacent peaks and valleys are connected by a straight line is 0. 30 to 1.00% by mass / nm , the average of the Ti concentration difference between the peak of adjacent peaks and the bottom of the valley is 2.5 to 15.0% by mass, the size in the structure observation of the cross section parallel to the rolling direction Observation field of second phase particles with a particle size of 3 μm or more 10000 μm Titanium copper in which the number per ² is 35 or less and the average crystal grain size in the structure observation of the cross section parallel to the rolling direction is 2 to 30 μm .
Here, the peak portion refers to a portion protruding above the average line in the Ti concentration fluctuation curve, and the valley portion refers to a portion protruding below the average line in the Ti concentration fluctuation curve. Shows a sample tilt angle of 0 °, an acceleration voltage of 200 kV, and an electron beam spot diameter of 0. 0 in a direction passing through an array of substantially circular regions showing a high concentration region of Ti obtained by mapping Ti in advance. The measurement is performed on five observation fields under the conditions of 2 nm and a measurement distance of 150 nm or more. Bending radius (R) / sheet thickness (with a bending width at which 0.2% proof stress in a direction parallel to the rolling direction is 900 MPa or more and plate width (w) / plate thickness (t) = 3.0 The titanium-copper according to claim 1, wherein no crack is generated in the bent portion when a W-bending test of Badway (the bending axis is the same direction as the rolling direction) is performed with t) = 0. 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 .