JP6080823B2 - 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 components such as lead frames and connectors used in electric / electronic devices and in-vehicle components have been miniaturized, and the tendency of narrowing and reducing the pitch of copper alloy members constituting the electronic components has been remarkable. The smaller the connector, the narrower the pin width, and the smaller the folded shape, so that the copper alloy 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 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.

  In addition, the copper alloy member used for the electronic component is given a bending stress within the elastic limit when the electronic component is operated, externally vibrated, and the component is attached and detached. In particular, in-vehicle components are used in an environment where severe vibration is repeatedly applied. When bending stress is repeatedly applied, fatigue cracks are generated from the bent part, and the cracks grow and lead to destruction of the member. For this reason, from the viewpoint of durability of electronic parts, it is also important as a characteristic of titanium copper for electronic parts that it has excellent fatigue characteristics that cracks in the bent part are hardly generated even when repeated bending stress is applied. Yes.

  Under such a background, Japanese Patent Laid-Open No. 2014-15679 (Patent Document 1) describes fatigue by increasing the area ratio of the S orientation {231} <346> in a crystal of titanium copper to 5 to 40%. A technique for improving the service life is described. According to the publication, compared with the conventional method for producing titanium copper, after hot rolling [Step 3], water cooling [Step 4], face cutting [Step 5], and cold rolling [Step 6] are used to reduce the rolling rate. A tension leveler that performs rolling at 80 to 99.8% and then corrects the tension at 100 to 300 MPa after reaching 100 to 400 ° C. at a temperature rising rate of 1 to 30 ° C./second so as not to be completely recrystallized. The area ratio of the S orientation in the recrystallized texture of the intermediate solution heat treatment [Step 9] is obtained by performing the correction by [Step 7] and further performing cold rolling [Step 8] at a processing rate of 2 to 50%. Is described to increase. It is also described that after the intermediate solution heat treatment [Step 9], an aging precipitation heat treatment [Step 10], finish cold rolling [Step 11] and temper annealing [Step 12] may be performed.

  In JP 2012-7215 A (Patent Document 2), titanium copper is produced in the order of final solution treatment → aging treatment → cold rolling, thereby producing titanium copper excellent in both strength and bending workability. The techniques to obtain are described. The gazette describes conditions for temperature rising and cooling during the solution treatment and rolling load during cold rolling.

  Japanese Patent Laid-Open No. 2006-265611 (Patent Document 3) describes titanium copper that defines volume resistivity and work hardening coefficient, with the object of obtaining titanium copper with improved spring characteristics after bending. Yes. As the manufacturing method of the titanium copper, hot rolling A, cold rolling B, solution treatment C, cold rolling D, aging treatment E are sequentially performed, and the cold rolling D has a workability of 35% or less and a rolling speed. Is an aging temperature of 380 to 450 ° C., an aging time of 9 to 18 hours, and a cooling rate in a temperature range of 300 ° C. or more during cooling is 35 to 80 ° C./hour. It is described.

  In JP 2010-261666 A (Patent Document 4), after the final solution treatment, heat treatment, cold rolling, and aging treatment performed under conditions of heating at a material temperature of 300 to 700 ° C. for 0.001 to 12 hours. A technique for improving the balance between the strength and bending workability of titanium copper by sequentially performing the steps described above.

  Japanese Patent Application Laid-Open No. 2014-84512 (Patent Document 5) defines a KAM (Kerner Average Misorientation) value representing a difference in orientation between adjacent measurement points in a crystal grain in a range of 1.5 to 3.0. In addition, a technique for improving the strength of titanium copper and the sag resistance at high temperature exposure is described. The document describes that after the final solution treatment, the properties of titanium copper are improved by performing the preliminary aging treatment and the aging treatment continuously without undergoing cold rolling.

JP 2014-15679 A JP 2012-7215 A JP 2006-265611 A JP 2010-261066 A JP 2014-84512 A

  The strength, bending workability and fatigue properties of titanium copper have been improved from various viewpoints, but as far as the present inventor knows, patents have attempted to improve all these three properties at the same time. It is only literature 1 and it is hard to say that research for this purpose has been exhausted. In Patent Document 1, although a technique for extending the fatigue life by increasing the S orientation accumulation ratio in the crystal is disclosed, it is considered that there are other means for improving the strength, bending workability, and fatigue strength in a well-balanced manner. In addition, there is a possibility that means exhibiting characteristics superior to those of Patent Document 1 exist. Accordingly, an object of the present invention is to improve the three characteristics of titanium copper, namely strength, bending workability and fatigue characteristics, by an approach different from the conventional one. It is an object of the present invention to provide titanium copper having a better balance of strength, bending workability and fatigue characteristics than conventional methods.

  The inventor has intensively studied to solve the above problems. Although the technique described in Patent Document 1 teaches that the S orientation accumulation ratio in the crystal is increased, it is said that it is preferable that the EBSD measurement for analyzing the crystal orientation is averaged in the thickness direction (Patent Document). 1 paragraph 0037). However, in view of the fatigue process in which fatigue cracks are generated from the bent portion by repeatedly applying bending stress, and this crack grows and leads to the destruction of the member, the surface structure of titanium copper is not improved in fatigue characteristics. We thought it was particularly important to control

  The present inventor further examined from the above viewpoint, and found that in the final cold rolling performed after the solution treatment, the strain on the material surface can be reduced by increasing the rear tension. Moreover, it discovered that precipitation of the 2nd phase particle | grains on the material surface was suppressed by implementing an aging treatment for a short time, respectively before and after the last cold rolling. And it was found that titanium copper, which has a small distortion on the surface of the material and little precipitation of second phase particles, is superior in strength, bending workability and fatigue characteristics. Further, when the distribution of KAM on the titanium copper material surface (rolled surface) is determined by EBSD measurement, the average KAM value, the ratio of the KAM value of 0 ° to less than 2 °, and the KAM value of 4 ° to 5 ° It was also found that the ratio of less than shows a specific value. The present invention has been completed based on the above findings.

  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 mass%, the balance is made of copper and inevitable impurities, and the average KAM value is 0 in the crystal orientation analysis in the EBSD measurement on the rolled surface. Titanium copper having a ratio of 6 ° to less than 1.5 ° and a KAM value of 0 ° to less than 2 ° of 80 to 100%.

  In one embodiment of titanium copper according to the present invention, in the crystal orientation analysis in the EBSD measurement with respect to the rolled surface, the ratio of the KAM value of 4 ° or more and less than 5 ° is 0 to 2.5%.

  In another embodiment of titanium copper according to the present invention, when a tensile test is performed according to JIS-Z2241 (2011), the 0.2% yield strength in the direction parallel to the rolling direction is 850 MPa or more.

In yet another embodiment of the titanium-copper according to the present invention, no fracture occurs when a swing stress of 550 N / mm ² is repeated 10 ⁷ times in the direction perpendicular to the rolling according to JIS-Z2273 (1978).

  In another embodiment of the titanium-copper according to the present invention, when the W bending test is performed in the Badway direction at r / t = 1.0 according to JIS-H3130 (2012), the average roughness on the outer peripheral surface of the bent portion Ra is 1.0 μm or less.

  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.

  Titanium copper excellent in the three characteristics of strength, bending workability and fatigue characteristics can be obtained. The titanium copper can be used for electronic parts such as conductive spring materials, lead frames, and connectors used in autofocus camera modules, and contributes to improving the reliability of these electronic parts.

It is a graph showing the suitable range of the material temperature and heating time in an aging treatment.

(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.
If the Ti concentration is less than 2.0% by mass, the precipitates are insufficiently deposited and the desired strength cannot be obtained. When the Ti concentration exceeds 4.0% by mass, the workability deteriorates and the material is easily cracked during rolling. Considering the balance between strength and 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 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 workability, one or more of the above elements is 0.1 to 0.4% by mass in total. It is preferable to contain.

(3) Distribution of KAM The KAM value represents an orientation difference between adjacent measurement points in a crystal grain, and is an analysis attached to EBSD by crystal orientation analysis in EBSD (Electron Back Scatter Diffraction) measurement. It can be calculated by measuring the orientation difference in the crystal grains using software (eg OIM Analysis manufactured by TSL Solutions).

  One feature of the present invention is that the KAM distribution on the surface of the titanium-copper material (rolled surface) is controlled within a specific extremely narrow range. It can be said that this indirectly indicates that the strain on the material surface and the precipitation of the second phase particles are very small. Although it is not intended that the present invention be limited by theory, the surface of the titanium copper according to the present invention is extremely uniform, and thus cracks may occur even when subjected to tensile force, vibration, or bending. It can be said that the starting point is hardly generated, and this is thought to lead to improvement in strength, bending workability and fatigue characteristics.

  In one embodiment of the titanium copper according to the present invention, the average KAM value is 0.6 ° or more and less than 1.5 °, the ratio of 0 to 2 ° of the KAM value is 80 to 100%, and the KAM value is The ratio of 4 ° or more and less than 5 ° is 0 to 2.5%. The KAM value is also an index for indirectly evaluating the dislocation density, and the KAM value tends to decrease as the dislocation density decreases, and conversely, increases as the dislocation density increases.

  In order to obtain excellent strength, the average KAM value is preferably 0.6 ° or more, more preferably 0.8 ° or more, and even more preferably 1.0 ° or more. On the other hand, if the average KAM value is too large, the KAM distribution becomes broad and the uniformity of the crystal structure on the surface of the material tends to be impaired, which adversely affects bending workability and fatigue characteristics. Is preferably less than or equal to 1.4 ° or less.

  Further, when cold rolling or aging treatment is performed, the distribution of KAM tends to be broad due to the introduction of strain, precipitation of second-phase particles, etc., but the titanium copper according to the present invention has a KAM value of 0 ° or more and 2 °. The ratio of the KAM value is as high as 80 to 100%, and the ratio of the KAM value of 4 ° to less than 5 ° is as low as 0 to 2.5%, that is, the distribution of KAM is narrow. Thereby, since the distribution of KAM is narrow while having a high average KAM value, it is considered that both strength, bending workability and fatigue characteristics can be achieved.

  A higher KAM value of 0 ° or more and less than 2 ° is more advantageous for improving the characteristics, preferably 80% or more, and more preferably 85% or more. However, since it tends to be difficult to increase the average KAM value if an attempt is made to increase the ratio of the KAM value from 0 ° to less than 2 °, the ratio of the KAM value from 0 ° to less than 2 ° tends to be difficult to increase. Is preferably 95% or less, more preferably 90% or less.

  A lower KAM value of 4 ° or more and less than 5 ° is advantageous for improving the characteristics, preferably 2.5% or less, and more preferably 2.0% or less. However, since it tends to be difficult to increase the average KAM value when trying to reduce the ratio of the KAM value of 4 ° or more and less than 5 °, the ratio of the KAM value of 4 ° or more and less than 5 ° from the viewpoint of the balance between the two. Is preferably 0.5% or more, more preferably 1.0% or more.

  In the present invention, for the stability of the measurement results, five distributions of KAM distribution at 200 μm × 200 μm per field are measured, and the average KAM value in each field, the ratio of KAM value of 0 ° or more and less than 2 °, The ratio of the KAM value of 4 ° or more and less than 5 ° is obtained, and the average value of the five fields of view is calculated as each measured value.

In the present invention, the following is adopted as measurement conditions in the EBSD measurement.
(A) SEM conditions ・ Beam conditions: acceleration voltage 15 kV, irradiation current amount 5 × 10 ⁻⁸ A
・ Work distance: 25mm
Observation field: 200 μm × 200 μm
・ Observation surface: Rolling surface ・ Pretreatment of observation surface: Electropolishing in a solution of phosphoric acid 67% + sulfuric acid 10% + water under conditions of 15 V × 60 seconds (b) EBSD conditions ・ Measurement program : OIM Data Collection
Data analysis program: OIM Analysis (Ver. 5.3)
・ Step width: 0.5μm

(4) 0.2% yield strength In one embodiment of the titanium copper according to the present invention, the 0.2% yield strength in a direction parallel to the rolling direction can achieve 850 MPa or more. The 0.2% yield strength of the titanium copper according to the present invention is 900 MPa or more in a preferred embodiment, 950 MPa or more in a more preferred embodiment, and 1000 MPa or more in a more preferred embodiment.

  The upper limit value of 0.2% proof stress is not particularly limited from the viewpoint of the intended strength of the present invention, but it takes time and effort, and since the KAM value becomes too large and the balance of characteristics is easily lost, The 0.2% proof stress of the titanium copper according to the invention is generally 1300 MPa or less, typically 1200 MPa or less, and more typically 1100 MPa or less.

  In the present invention, the 0.2% proof stress in the direction parallel to the rolling direction of titanium copper is measured according to JIS-Z2241 (2011) (metallic material tensile test method).

(5) Fatigue properties Titanium copper according to the present invention can have excellent fatigue properties. In one embodiment, the titanium-copper according to the present invention has a characteristic that it does not break when a swing stress of 550 N / mm ² is repeated 10 ⁷ times in the direction perpendicular to the rolling according to JIS-Z2273 (1978).

(6) Bending workability The titanium copper according to the present invention can have excellent bending workability. In the titanium copper according to the present invention, in one embodiment, when the W bending test is performed in the Badway direction at r / t = 1.0 according to JIS-H3130 (2012), the average roughness Ra on the outer peripheral surface of the bent portion. Has a characteristic of 1.0 μm or less. The average roughness Ra is calculated according to JIS-B0601 (2013). That the average roughness of a bending part is small also after a bending process means that the harmful crack which may cause a fracture | rupture does not enter into a bending part easily. Generally, the average roughness Ra of the surface of the titanium copper according to the present invention before the bending test is 0.2 μm or less.

(7) Thickness of titanium copper In one embodiment of titanium copper according to the present invention, the thickness can be 1.0 mm or less, and in a typical embodiment, the thickness is 0.02 to 0.8 mm. In a more typical embodiment, the thickness can be 0.05-0.5 mm.

(8) Crystal grain size From the viewpoint of improving the strength, bending workability and fatigue characteristics in a balanced manner, in one embodiment of titanium copper according to the present invention, the average crystal grain size on the rolled surface is controlled in the range of 2 to 30 μm. It is preferable to control within the range of 2 to 15 μm, and it is even more preferable to control within the range of 2 to 10 μm. By the cutting method based on JIS-H0501 (1986), the average crystal grain size in the direction perpendicular to the rolling direction and the average crystal grain size in the direction parallel to the rolling direction are obtained, and the average value of both is taken as the measured value.

(9) Applications The titanium copper according to the present invention can be processed into various copper products, for example, plates, strips, tubes, rods and wires. The titanium copper according to the present invention is not limited, but includes a switch, a connector (particularly, a fork-type FPC connector that does not require severe bending workability), an autofocus camera module, a jack, and a terminal (particularly, a battery terminal). It can be suitably used as a conductive material or a spring material in electronic parts such as relays. These electronic components can be used, for example, as vehicle-mounted components or components for electric / electronic devices.

(10) Manufacturing method A preferred example of manufacturing titanium copper according to the present invention will be described step by step.

<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.

  It is preferable to perform homogenization annealing again after hot rolling. It aims at making the 2nd phase particle which precipitates during a hot rolling form a solid solution again. The conditions are heating to 900 to 970 ° C. for 3 to 24 hours, and cooling with water after heating. If this step is not performed, the KAM distribution is likely to be broad even if the solution treatment and the subsequent steps are appropriately performed, and it is difficult to obtain desired characteristics.

<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, 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.

<Aging treatment>
An aging treatment is performed following the final solution treatment. The aging treatment here is preferably carried out at a low temperature and in a short time as compared with a general aging treatment. Specifically, it is preferable to perform an aging treatment in relation to the material temperature and heating time in the formula (1), and it is more preferable to perform an aging treatment in relation to the material temperature and the heating time in the formula (2). It is even more preferable to perform an aging treatment in relation to the material temperature and the heating time. In FIG. 1, formulas (1) to (3) are represented on a graph.
Formula (1): −13x + 6500 ≦ y ≦ −13x + 8900
Formula (2): −13x + 6700 ≦ y ≦ −13x + 8700
Formula (3): −13x + 6900 ≦ y ≦ −13x + 8500
(Where, x = material temperature (° C.), y = heating time (seconds), 350 ≦ x ≦ 650, 1 ≦ y ≦ 3600)
The aging treatment is preferably performed in an inert atmosphere of Ar, N ₂ , H ₂ or the like in order to suppress the generation of an oxide film. When the material temperature exceeds 650 ° C. or the aging treatment time exceeds 3600 seconds, the second phase particles due to the aging treatment precipitate on the material surface, the distribution of KAM becomes broad, and the fatigue characteristics are impaired.

<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 rolling reduction is 5 to 50%, preferably 20 It is desirable to set it to ˜40%. Further, the rear tension in the cold rolling is set in the range of 20 to 80% of the 0.2% proof stress in the direction parallel to the rolling direction of the material before the cold rolling (in other words, after the previous aging treatment). Is preferable, and the range of 40 to 60% is more preferable. In conventional cold rolling, it is customary to set the rear tension to about 0 to 20% of the 0.2% proof stress of the material before cold rolling. By increasing the back tension, the amount of strain on the material surface can be suppressed, the average KAM value is reduced, the distribution of KAM is narrowed, and the fatigue characteristics are improved.

<Final aging treatment>
Subsequent to the final cold rolling, a final aging treatment is performed. It is desirable that the aging treatment here is performed at a low temperature and in a short time as compared with a general aging treatment. Specifically, it is preferable to perform an aging treatment in relation to the material temperature and heating time in the formula (1), and it is more preferable to perform an aging treatment in relation to the material temperature and the heating time in the formula (2). It is even more preferable to perform an aging treatment in relation to the material temperature and the heating time. In FIG. 1, formulas (1) to (3) are represented on a graph.
Formula (1): −13x + 6500 ≦ y ≦ −13x + 8900
Formula (2): −13x + 6700 ≦ y ≦ −13x + 8700
Formula (3): −13x + 6900 ≦ y ≦ −13x + 8500
(Where, x = material temperature (° C.), y = heating time (seconds), 350 ≦ x ≦ 650, 1 ≦ y ≦ 3600)
The aging treatment is preferably performed in an inert atmosphere of Ar, N ₂ , H ₂ or the like in order to suppress the generation of an oxide film. When the material temperature exceeds 650 ° C. or the aging treatment time exceeds 3600 seconds, the second phase particles due to the aging treatment precipitate on the material surface, the distribution of KAM becomes broad, and the fatigue characteristics are impaired.

To summarize the above, in one embodiment of the method for producing titanium copper according to the present invention,
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. A step of casting an ingot having a composition of 0 to 0.5% by mass in total and the balance of copper and inevitable impurities,
A step of hot rolling the ingot;
A process of homogenizing annealing after hot rolling and water cooling;
Then, the step of heating to a temperature of −20 ° C. to + 50 ° C. with respect to the temperature at which the solid solubility limit of Ti is the same as the addition amount, and performing a final solution treatment;
Following the final solution treatment, the following formula: −13x + 6500 ≦ y ≦ −13x + 8900 (where x = material temperature (° C.), y = heating time (seconds), 350 ≦ x ≦ 650, 1 ≦ y ≦ 3600.) performing an aging treatment under conditions satisfying the relationship between the material temperature and the heating time represented by:
Following the aging treatment, the final tension is controlled at a reduction rate of 5 to 50% while controlling the rear tension in the range of 20 to 80% of the 0.2% proof stress in the direction parallel to the rolling direction of the material after the aging treatment. A process of cold rolling;
Following the final cold rolling, the following formula: −13x + 6500 ≦ y ≦ −13x + 8900 (where x = material temperature (° C.), y = heating time (seconds), 350 ≦ x ≦ 650, 1 ≦ y ≦ 3600.) a step of performing a final aging treatment under conditions satisfying the relationship between the material temperature and the heating time represented by:
including.

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

  An alloy containing the alloy components shown in Table 1 and the balance being copper and inevitable impurities is used as an experimental material, and the alloy components, KAM distribution on the rolled surface, and manufacturing conditions are 0.2% proof stress, bending workability, and fatigue characteristics. The effects on the environment were investigated.

  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.

  The ingot is heated at 950 ° C. for 3 hours, followed by hot rolling at 900 to 950 ° C., followed by homogenization annealing and water cooling at 950 ° C. for 3 hours. A hot rolled sheet was obtained. After descaling by chamfering, cold rolling was performed to obtain a strip thickness (2 mm), and a first solution treatment with the strip was performed. The conditions for the first 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 the product sheet thickness in the final cold rolling described in Table 1 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 0.0 mass% and about 840 ° C.) as a standard. Next, an aging treatment was performed under the conditions described in Table 1 in an Ar atmosphere. After descaling by pickling, the final cold rolling was performed under the conditions described in Table 1 to a sheet thickness of 0.15 mm, and finally aging treatment was performed under each heating condition described in Table 1 to test the invention examples and comparative examples. It was a piece. Depending on the test piece, one or more steps of homogenization annealing and water cooling after hot rolling, aging treatment after final solution treatment, final cold rolling, and final aging treatment were omitted.

The following evaluation was performed about the produced test piece.
(A) Crystal grain size The average crystal grain size (μm) of each test piece was determined as follows. After polishing the plate surface (rolled surface) of each test piece, the surface was observed with an optical microscope, and the grain size of 100 or more crystal grains was cut according to JIS-H0501 (1986) in a 300 μm × 300 μm field of view. And the average crystal grain size was determined.
(B) 0.2% yield strength A JIS No. 13B test piece was prepared, and the 0.2% yield strength in the direction parallel to the rolling direction was measured using a tensile tester according to the measurement method described above.
(C) Roughness of the outer peripheral surface of the bent portion In accordance with JIS-H3130 (2012), a W bending test was performed with Badway (bending axis being the same direction as the rolling direction), r / t = 1.0, and bending of this test piece The outer peripheral surface of the part was observed. As an observation method, the outer peripheral surface of the bent part was photographed using a laser tech confocal microscope HD100, and the average roughness Ra (conforming to JIS-B0601: 2013) was measured using the attached software and compared. In addition, when the sample surface before a bending process was observed using the confocal microscope, the unevenness | corrugation was not able to be confirmed but all average roughness Ra was 0.2 micrometer or less. The case where the surface average roughness Ra after bending was 1.0 μm or less was evaluated as “◯”, and the case where Ra exceeded 1.0 μm was evaluated as “×”.
(D) Fatigue properties In accordance with JIS-Z2273 (1978), a test was conducted by repeatedly applying a swinging stress of 550 N / mm ² 10 ⁷ times in the direction perpendicular to the rolling direction.
(E) Distribution of KAM The distribution of KAM was calculated | required with the measuring method mentioned above using OIM-Analysis made from TSL Solutions. From the obtained KAM distribution, the average KAM value, the ratio of the KAM value of 0 ° to less than 2 °, and the ratio of the KAM value of 4 ° to less than 5 ° were determined.

(Discussion)
Table 2 shows the test results. In Invention Examples 1 to 18, the KAM distribution was appropriate, the 0.2% proof stress was as high as 850 MPa or more, the bending workability was excellent, and the fatigue characteristics were excellent.
On the other hand, in Comparative Example 1, since homogenization annealing and water cooling after hot rolling were not performed, the distribution of KAM became inappropriate, and the bending workability and fatigue characteristics did not reach the levels of the inventive examples.
In Comparative Example 2, an unrecrystallized region was generated because the final solution treatment temperature was too low, and the distribution of KAM became inappropriate. Therefore, bending workability and fatigue characteristics did not reach the level of the inventive examples.
In Comparative Example 3, since the final solution treatment temperature was too high, the crystal grains became coarse and the KAM distribution was also outside the scope of the present invention, so that 0.2% proof stress, bending workability and fatigue characteristics were obtained. Both were inferior to the invention examples.
In Comparative Example 4, since the aging treatment after the solution treatment was not performed, the distribution of KAM became inappropriate, and the bending workability and the fatigue characteristics did not reach the level of the inventive example.
Comparative Example 5 was obtained by the production method described in JP-A-2006-265611. Here, the final rolling speed was set to 100 m / min, and care was taken so that the cooling speed in the temperature range of 300 ° C. or higher during cooling in the final aging treatment was 40 ° C./hour. According to this method, the distribution of KAM became inappropriate, and the fatigue characteristics did not reach the level of the inventive example.
In Comparative Example 6, the KAM distribution became inappropriate because the heating temperature in the aging treatment after the solution treatment was too low. Therefore, bending workability and fatigue characteristics did not reach the level of the inventive examples.
In Comparative Example 7, the KAM distribution became inappropriate because the heating temperature in the aging treatment after the solution treatment was too high. Therefore, bending workability and fatigue characteristics did not reach the level of the inventive examples.
In Comparative Example 8, since the final aging treatment was not performed, the distribution of KAM became inappropriate, and the bending workability and fatigue characteristics did not reach the level of the inventive example.
In Comparative Example 9, the KAM distribution became inappropriate because the heating temperature in the final aging treatment was too low. Therefore, bending workability and fatigue characteristics did not reach the level of the inventive examples.
In Comparative Example 10, the KAM distribution became inappropriate because the heating temperature in the final aging treatment was too high. Therefore, 0.2% proof stress and fatigue characteristics did not reach the level of the inventive examples.
Comparative Example 11 was obtained by the production method described in Japanese Patent Application Laid-Open No. 2010-261066. According to this method, the distribution of KAM became inappropriate, and the bending workability did not reach the level of the invention example.
In Comparative Example 12, the rear tension in the final cold rolling was too low, so the distribution of KAM became inappropriate, and the bending workability did not reach the level of the inventive example.
In Comparative Example 13, since the rear tension in the final cold rolling was too high, the material was broken during rolling, and the subsequent steps could not be performed.
In Comparative Example 14, since the final cold rolling was not performed, the distribution of KAM became inappropriate, and the 0.2% proof stress and fatigue characteristics did not reach the level of the inventive example.
In Comparative Example 15, since the reduction ratio in the final cold rolling was too high, the distribution of KAM became inappropriate, and the bending workability did not reach the level of the inventive example.
Comparative Example 16 was obtained by the production method described in JP 2014-15679 A. Here, it is confirmed that the cooling rate at the time of manufacturing the ingot is within a range of 0.1 to 100 ° C./second, and instead of the first solution treatment, heating is performed at a temperature rising rate of 20 ° C./second, 300 After reaching to ° C., correction with a tension leveler with a tension of 200 MPa was also performed. The obtained titanium copper had an inappropriate distribution of KAM, and 0.2% proof stress, bending workability and fatigue characteristics were all inferior to those of the inventive examples.
Comparative Example 17 was obtained by the production method described in JP2012-7215A. According to this method, the distribution of KAM became inappropriate, and the fatigue characteristics did not reach the level of the inventive example.
Comparative example 18 corresponds to comparative example 3 of Japanese Patent Application Laid-Open No. 2014-84512. In this example, the average KAM value falls within the range of the present invention, but the ratio of the KAM value of 0 ° or more and less than 2 ° and the ratio of the KAM value of 4 ° or more and less than 5 ° are inappropriate, and the fatigue characteristics of the invention example The level was not reached.
In Comparative Example 19, the test piece could not be produced because the amount of the third element added was too large.
In Comparative Example 20, since the Ti concentration was too low, the distribution of KAM became inappropriate, and the 0.2% proof stress, bending workability and fatigue characteristics did not reach the level of the inventive example.
In Comparative Example 21, since the Ti concentration was too high, cracking occurred during hot rolling, and thus the test piece could not be manufactured.

Claims (7)

  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 crystal orientation analysis in the EBSD measurement for the rolled surface, the average KAM value is 0.6 ° or more and 1.5 or more. Titanium copper having a KAM value of 0 ° or more and less than 2 ° of 80 to 100%.   The titanium-copper according to claim 1, wherein in the crystal orientation analysis in the EBSD measurement with respect to the rolled surface, the ratio of the KAM value of 4 ° or more and less than 5 ° is 0 to 2.5%.   The titanium-copper according to claim 1 or 2, wherein a 0.2% proof stress in a direction parallel to the rolling direction when a tensile test is performed according to JIS-Z2241 (2011) is 850 MPa or more. Titanium copper as described in any one of Claims 1-3 in which a fracture | rupture does not arise when the double swing stress of 550 N / mm < ² > is repeated 10 < ⁷ > times in the rolling orthogonal direction according to JIS-Z2273 (1978).   The average roughness Ra of the outer peripheral surface of the bent portion is 1.0 μm or less when the W bending test is performed in the Badway direction at r / t = 1.0 according to JIS-H3130 (2012). Titanium copper as described in any one.   A rolled copper product comprising the titanium copper according to any one of claims 1 to 5.   The electronic component provided with the titanium copper as described in any one of Claims 1-5.

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