Cu-Ti-Al copper alloy sheets, electronic equipment components, conductive components, and heat dissipation components.

Abstract

To provide a Cu-Ti-based copper alloy sheet material having all of good strength, bendability, conductivity, fatigue characteristics and spring bending elastic limit and reduced density (specific gravity).SOLUTION: There is provided a copper alloy sheet material comprising: in mass %, Ti: 1.00 to 5.00%, Al: 0.50 to 3.00%, Ag: 0 to 0.30%, B: 0 to 0.30%, Co: 0 to 1.00%, Cr: 0 to 1.00%, Fe: 0 to 1.00%, Mg: 0 to 1.00%, Mn: 0 to 2.00%, Nb: 0 to 1.00%, Ni: 0 to 1.00%, P: 0 to 0.50%, S: 0 to 0.20%, Si: 0 to 0.50%, Sn: 0 to 2.00%, V: 0 to 1.00%, Zn: 0 to 3.00%, Zr: 0 to 1.00% and a rare earth element: 0 to 3.00%, the total of elements excluding the above elements and Cu: 0.50% or less, Ti / Al being 1.50 or more with the balance substantially being Cu, and having an average crystal grain size, a number density of coarse deposit particles, a tensile strength of LD and a spring bending elastic limit of TD within predetermined ranges.SELECTED DRAWING: None

Description

[Technical Field]

[0001] This invention relates to a Cu-Ti-Al copper alloy sheet material with reduced density (specific gravity), and to electronic equipment components, power-conducting components, and heat-dissipating components using the sheet material. [Background technology]

[0002] Cu-Ti copper alloys (titanium copper) are used as spring components for electrical conduction in connectors, relays, switches, and other devices due to their high strength level and good stress relaxation resistance compared to other copper alloys. In recent years, with the increasing sophistication of mobile devices such as smartphones and automotive electronic equipment, there has been a growing demand for weight reduction in the individual components used. To meet this demand, it is important to reduce the density (specific gravity) of the copper alloy material used for these components. On the other hand, in order to obtain highly reliable components while meeting the demands for miniaturization and thinning, it is also important to improve fatigue characteristics and spring limit values ​​in addition to achieving both strength and bendability.

[0003] To date, various techniques have been explored to achieve both strength and bendability in Cu-Ti copper alloy materials, as seen in the following patent documents. However, a method has not yet been established that simultaneously improves fatigue characteristics and spring limit values ​​while reducing density (specific gravity).

[0004] Patent Document 1 describes a method for improving the fatigue properties of a Cu-Ti copper alloy by performing hot rolling followed by cold rolling, and then a heat treatment in which the alloy is heated to 100-400°C while being straightened with a tension leveler. However, this method makes it difficult to improve the spring limit (see Comparative Example No. 57 below).

[0005] Patent Document 2 describes a process in which, in Cu-Ti copper alloys, fatigue properties are improved by performing a preliminary treatment involving solution treatment followed by heating at 550-730°C for a relatively short time, and then cold rolling and aging treatment. However, it is difficult to obtain a material with a high spring limit using the technology disclosed in Patent Document 2.

[0006] Patent Document 3 describes a technique for obtaining a material with a high spring limit value in a Cu-Ti copper alloy by performing aging treatment without cold rolling after a second solution treatment, followed by cold rolling and stress-relieving annealing. Since the Cu-Ti copper alloy in Patent Document 3 is Al-free, applying the above process tends to result in a large amount of coarse precipitate particles, making it difficult to improve fatigue properties (see Comparative Example No. 58 below).

[0007] Patent Document 4 describes a method for obtaining a Cu-Ti copper alloy in which the size of the grain boundary reaction phase is controlled by performing a solution treatment once, followed by aging treatment and cooling to 300°C at 10-80°C / h, and then cold rolling. However, high spring limit values ​​are not always obtained. Furthermore, since the Cu-Ti copper alloy in Patent Document 4 is Al-free, applying the above process tends to result in a large amount of coarse precipitate particles, making it difficult to improve fatigue properties (see Comparative Example No. 59 below).

[0008] Patent Document 5 describes a process in which a Cu-Ti copper alloy is hot-rolled followed by cold-rolling, then a solution treatment is performed once, followed by aging treatment at 300-550°C, and if necessary, cold-rolling and stress-relieving annealing are performed to obtain a microstructure with high integrated strength of the (311) plane. Since the Cu-Ti copper alloy in Patent Document 5 is Al-free, applying the above process tends to coarseen precipitates, making it difficult to improve fatigue properties and spring limit values ​​(see Comparative Example No. 60 below).

[0009] Patent Document 6 describes a process for obtaining a Cu-Ti copper alloy with high integrated strength of the (420) plane by performing hot rolling followed by cold rolling, then a single solution treatment, followed by cold rolling as needed, aging treatment at 300-500°C, and then cold rolling and low-temperature annealing as needed. However, since the solution treatment is performed only once and the cooling rate after the aging treatment is not specified, it is thought that a large amount of coarse precipitates will be produced during the cooling process of the aging treatment, making it difficult to improve the fatigue properties (see Comparative Example No. 61 below). [Prior art documents] [Patent Documents]

[0010] [Patent Document 1] Japanese Patent Publication No. 2014-15679 [Patent Document 2] Japanese Patent Publication No. 2014-185370 [Patent Document 3] Japanese Patent Publication No. 2012-62575 [Patent Document 4] Japanese Patent Publication No. 2012-207254 [Patent Document 5] Japanese Patent Publication No. 2013-82960 [Patent Document 6] Japanese Patent Publication No. 2010-126777 [Overview of the project] [Problems that the invention aims to solve]

[0011] The technologies disclosed in the above-mentioned patent documents have made it possible to obtain Cu-Ti copper alloy sheet materials that have good strength and bendability. However, as mentioned above, a method for simultaneously improving fatigue characteristics and spring limit values ​​has not yet been established.

[0012] In addition to having good strength, bendability, and conductivity, the present invention aims to provide a Cu-Ti-based copper alloy sheet having improved fatigue characteristics and spring limit values, and a reduced density (specific gravity), and to provide a component that makes use of the characteristics of the sheet.

Means for Solving the Problems

[0013] To achieve the above object, the following inventions are disclosed in this specification. [1] In mass %, Ti: 1.00 to 5.00%, Al: 0.50 to 3.00%, Ag: 0 to 0.30%, B: 0 to 0.30%, Co: 0 to 1.00%, Cr: 0 to 1.00%, Fe: 0 to 1.00%, Mg: 0 to 1.00%, Mn: 0 to 2.00%, Nb: 0 to 1.00%, Ni: 0 to 1.00%, P: 0 to 0.50%, S: 0 to 0.20%, Si: 0 to 0.50%, Sn: 0 to 2.00%, V: 0 to 1.00%, Zn: 0 to 3.00%, Zr: 0 to 1.00%, total of rare earth elements: 0 to 3.00%, total of Ag, B, Co, Cr, Fe, Mg, Mn, Nb, Ni, P, S, Si, Sn, V, Zn, Zr and rare earth elements: 3.00% or less, total of elements other than Ti, Al, Ag, B, Co, Cr, Fe, Mg, Mn, Nb, Ni, P, S, Si, Sn, V, Zn, Zr, rare earth elements and Cu: 0 to 0.50%, the balance being Cu, having a composition in which the content ratio Ti / Al of Ti and Al in mass ratio is 1.50 or more, the average crystal grain size by the cutting method according to JIS H0501-1986 on the observation plane parallel to the sheet surface is 1 to 20 μm, and the number density of coarse precipitate particles having a major axis of 1.0 μm or more on the observation plane parallel to the sheet surface is 1.0×10 5 per mm 2 or less, and a copper alloy sheet having a tensile strength in the rolling parallel direction of 850 MPa or more and a spring limit value in the direction perpendicular to rolling of 400 MPa or more. [2] The copper alloy sheet according to [1] above, wherein the Nb content is 0 to 0.50 mass %. [3] When the KAM value is 3.00° or less when the boundary with a crystal orientation difference of 15° or more is regarded as a grain boundary in the measurement at a step size of 0.1 μm by EBSD (electron backscatter diffraction method) on an observation plane parallel to the plate surface, the copper alloy sheet according to the above [1] or [2]. [4] The copper alloy sheet according to any one of the above [1] to [3], having a conductivity of 10.0% IACS or more. [5] In the W bending test according to B.W. in accordance with the Japan Copper Development Association Technical Standard JCBA T307:2007, the ratio MBR / t of the minimum bending radius MBR at which cracking does not occur to the plate thickness t is 2.0 or less, the copper alloy sheet according to any one of the above [1] to [4]. [6] In the cantilever resonance method two-way vibration fatigue test using a test piece with the longitudinal direction perpendicular to the rolling direction, the fatigue limit at a load stress of 450 MPa is 10 7 cycles or more, the copper alloy sheet according to any one of the above [1] to [5]. [7] The density is 8.53 g / cm 3 or less, the copper alloy sheet according to any one of the above [1] to [⑥]. [8] Electronic device parts using the copper alloy sheet according to any one of the above [1] to [7] as a material. [9] Electrical connection parts using the copper alloy sheet according to any one of the above [1] to [7] as a material.

[10] Heat dissipation parts using the copper alloy sheet according to any one of the above [1] to [7] as a material.

[0014] The copper alloy sheets according to the above [1] to [7] can be manufactured, for example, by the following methods.

[11] In the process of manufacturing a copper alloy sheet by subjecting an intermediate product sheet having the above composition to a first solution treatment, a first intermediate cold rolling, a second solution treatment, a second intermediate cold rolling, and an aging treatment in this order, The first solution treatment is carried out under the condition of holding at a temperature range of 800 to 900 °C for 20 to 600 seconds, The first intermediate cold rolling is carried out at a rolling rate of 70% or more, The second solution treatment is carried out under the condition of holding at a temperature range of 750 to 860 °C for 10 to 300 seconds, The second intermediate cold rolling is carried out at a rolling rate of 15 to 50%, The aging treatment is carried out under the conditions that the maximum reaching temperature T0 (°C) is in the range of 320°C or higher and 450°C or lower, the holding temperature range is [T0 - 10°C] or higher and T0 or lower, and after performing heat holding with the holding time in the holding temperature range being 5 to 20 hours, the average cooling rate from [T0 - 10°C] to 300°C is 30 to 60°C / h, and the average cooling rate from 300°C to 150°C is 20°C / h or lower for cooling. A method for manufacturing a copper alloy sheet.

[12] The method for manufacturing a copper alloy sheet according to

[11] above, wherein a sheet having a spring limit value in the rolling right angle direction of 400 MPa or higher is obtained.

[0015] In this specification, the notation "n1~n2" indicating a numerical range means "n1 or more and n2 or less". Here, n1 and n2 are numerical values satisfying n1 < n2. "Sheet material" means a sheet-like metal material formed by utilizing the malleability of a metal. A thin sheet-like metal material may be called "foil", and such "foil" is also included in the "sheet material" referred to here. A long sheet-like metal material wound in a coil shape is also included in the "sheet material". In this specification, the thickness of the sheet-like metal material is called "sheet thickness". "Sheet surface" is a surface perpendicular to the sheet thickness direction of the sheet material. "Sheet surface" may also be called "rolling surface".

Advantages of the Invention

[0016] According to the present invention, it has become possible to realize a Cu-Ti-based copper alloy sheet that兼备 all of high strength, bending workability, conductivity, fatigue characteristics, and spring limit value at a high level and has a low density (low specific gravity).

Embodiments for Carrying out the Invention

[0017] [Chemical Composition] Hereinafter, "%" regarding alloy components means "mass%" unless otherwise specified. Titanium (Ti) is an element that contributes to increasing the strength of the Cu-Ti-Al copper alloy of the present invention by causing the formation of a modulated structure of Ti through spinodal decomposition and the formation of fine second-phase particles through precipitation. It also contributes to improving stress relaxation resistance and reducing density (specific gravity). Here, we focus on alloys with a Ti content of 1.00% or more. From the viewpoint of precipitation strengthening, a Ti content of 1.50% or more is more preferable, and 2.50% or more is even more preferable. Excessive Ti content can reduce hot workability and cold workability, as well as bendability, so the Ti content should be 5.00% or less. It may also be controlled to 4.50% or less, or 4.00% or less.

[0018] Aluminum (Al) is an effective element for reducing the density (specific gravity) of Cu-Ti-Al copper alloys. Furthermore, research by the inventors has shown that Al is effective in suppressing the formation of coarse precipitates in Cu-Ti-Al copper alloys. To fully realize these effects, an Al content of 0.50% or more should be ensured. A content of 0.70% or more is more effective, and 1.00% or more is even more effective. Adding more than 0.50% Al to Cu-Ti copper alloys generally presents a problem in achieving both strength and bendability. However, this problem can be resolved by the manufacturing method described later. However, since excessive Al content reduces conductivity, the Al content is limited to 3.00% or less. An Al content of 2.80% or less is preferable.

[0019] The Ti and Al content should be adjusted so that the Ti / Al ratio, which represents the mass percentage ratio of Ti to Al, is 1.50 or higher. If the Ti / Al ratio is too low, it can easily lead to insufficient conductivity or strength, and the balance between strength and conductivity may be poor. The Ti / Al ratio will inevitably be 10.00 or less to satisfy the above-mentioned Ti and Al content ranges, but it may also be adjusted to a range of, for example, 7.00 or less, or 5.00 or less.

[0020] Ag (silver), B (boron), Co (cobalt), Cr (chromium), Fe (iron), Mg (magnesium), Mn (manganese), Nb (niobium), Ni (nickel), P (phosphorus), S (sulfur), Si (silicon), Sn (tin), V (vanadium), Zn (zinc), Zr (zirconium), and rare earth elements are optional elements. One or more of these can be included as needed. For example, Ni, Co, Fe, and Nb form intermetallic compounds with Ti, contributing to improved strength. Furthermore, these intermetallic compounds suppress grain coarsening, enabling solution treatment at higher temperatures in the manufacturing of copper alloy sheets, which is advantageous for sufficient solid solution of Ti. Suppression of grain coarsening is also advantageous in terms of fatigue properties. Fe, in particular, is useful for improving strength and fatigue properties. Ag and Sn have solid solution strengthening effects and effects that improve stress relaxation resistance. Zn improves solderability and strength, as well as castability. Mg improves stress relaxation resistance and has a desulfurization effect. Si can form compounds with Ti, contributing to pinning during recrystallization in the manufacture of copper alloy sheets and potentially reducing grain size. Cr and Zr are effective for dispersion strengthening and suppressing grain coarsening. Mn and V readily form high-melting-point compounds with S, etc., and B and P have a refinement effect on the cast structure, thus contributing to improved hot workability. Rare earth elements (REM) are Sc (scandium), Y (yttrium) from Group 3 of the periodic table, and lanthanide elements (excluding Pm (promethium)). The inclusion of rare earth elements is effective for grain refinement and dispersion of precipitates. Mischmetal (a mixture of rare earth elements) may be used as a source of rare earth elements.

[0021] The content of the above-mentioned arbitrary elements can be in the range of Ag: 0-0.30%, B: 0-0.30%, Co: 0-1.00%, Cr: 0-1.00%, Fe: 0-1.00%, Mg: 0-1.00%, Mn: 0-2.00%, Nb: 0-1.00%, Ni: 0-1.00%, P: 0-0.50%, S: 0-0.20%, Si: 0-0.50%, Sn: 0-2.00%, V: 0-1.00%, Zn: 0-3.00%, Zr: 0-1.00%, and the total of rare earth elements: 0-3.00%. Regarding rare earth elements, for example, the mixture may contain one or more elements selected from La (lanthanum): 2.00% or less, Ce (cerium): 1.80% or less, Pr (praseodymium): 0.30% or less, Nd (neodymium): 0.80% or less, Sm (samarium): 2.50% or less, and Y (yttrium): 2.50% or less, with a total rare earth element content of 3.00% or less. In the above, the Nb content may be specified as 0 to 0.50%.

[0022] Furthermore, it is more preferable that the content of the above-mentioned arbitrary elements be within the range of Ag: 0-0.20%, B: 0-0.20%, Co: 0-0.50%, Cr: 0-0.50%, Fe: 0-0.50%, Mg: 0-0.50%, Mn: 0-1.80%, Nb: 0-0.30%, Ni: 0-0.50%, P: 0-0.20%, S: 0-0.10%, Si: 0-0.20%, Sn: 0-1.50%, V: 0-0.50%, Zn: 0-2.00%, Zr: 0-0.50%, and the total of rare earth elements: 0-2.00%. In this case, a range of rare earth element content that takes economics and manufacturability into consideration can be, for example, a range in which one or more elements selected from La: 0.60% or less, Ce: 0.70% or less, Pr: 0.10% or less, Nd: 0.20% or less, Sm: 1.00% or less, and Y: 1.00% or less are included, and the total content of rare earth elements is 1.50% or less.

[0023] Furthermore, the content of the above-mentioned optional elements may be controlled to be within the range of Ag: 0-0.15%, B: 0-0.15%, Co: 0-0.20%, Cr: 0-0.20%, Fe: 0-0.20%, Mg: 0-0.45%, Mn: 0-1.50%, Nb: 0-0.15%, Ni: 0-0.20%, P: 0-0.15%, S: 0-0.04%, Si: 0-0.03%, Sn: 0-1.30%, V: 0-0.20%, Zn: 0-1.80%, Zr: 0-0.20%, and the total of rare earth elements: 0-1.00%. In this case, a more preferable range of rare earth element content, taking into further consideration economic efficiency and manufacturability, is, for example, a range in which one or more elements selected from La: 0.35% or less, Ce: 0.32% or less, Pr: 0.04% or less, Nd: 0.10% or less, Sm: 0.50% or less, and Y: 0.50% or less are included, and the total content of rare earth elements is 0.80% or less.

[0024] The total content of the above-mentioned optional elements Ag, B, Co, Cr, Fe, Mg, Mn, Nb, Ni, P, S, Si, Sn, V, Zn, Zr, and rare earth elements shall be within the range of 3.00% or less (including cases where it is 0%). The upper limit of the total content of these optional elements is preferably 2.00% or less, and may be controlled to 1.60% or less.

[0025] Other elements may also be included as long as they do not hinder the objectives of the present invention (combining good strength, bendability, conductivity, fatigue characteristics, spring limit value, and low density). Specifically, the total content of elements other than Ti, Al, Ag, B, Co, Cr, Fe, Mg, Mn, Nb, Ni, P, S, Si, Sn, V, Zn, Zr, rare earth elements, and Cu (copper) should be controlled to 0.50% or less (including 0%), or it may be controlled to 0.10% or less (including 0%).

[0026] One example of an alloy composition where the total content of elements excluding Ti, Al, Ag, B, Co, Cr, Fe, Mg, Mn, Nb, Ni, P, S, Si, Sn, V, Zn, Zr, rare earth elements, and Cu (copper) is 0.10% or less is, for example, "by mass%, Ti: 1.00~5.00%, Al: 0.50~3.00%, Ag: 0~0.30%, B: 0~0.30%, Co: 0~1.00%, Cr: 0~1.00%, Fe: 0~1.00%, Mg: 0~1.00%, Mn: 0~2.00%, Nb: 0~1.00% or 0~0.50%." An example composition is one in which Ni: 0-1.00%, P: 0-0.50%, S: 0-0.20%, Si: 0-0.50%, Sn: 0-2.00%, V: 0-1.00%, Zn: 0-3.00%, Zr: 0-1.00%, and the total of rare earth elements is 0-3.00%, with the total of Ag, B, Co, Cr, Fe, Mg, Mn, Nb, Ni, P, S, Si, Sn, V, Zn, Zr, and rare earth elements being 3.00% or less, and the remainder consisting of Cu and unavoidable impurities, with a mass percentage Ti / Al content ratio of 1.50 or more. In this case, unavoidable impurities refer to elements that are inevitably mixed in during manufacturing, other than the elements listed above.

[0027] [Average grain size] In the Cu-Ti-Al copper alloy sheet material having the above chemical composition, good bendability and fatigue properties are obtained when the average grain size measured by the cutting method conforming to JIS H0501-1986 on an observation surface parallel to the sheet surface is 1 to 20 μm. The above average grain size is more preferably 15 μm or less, and even more preferably 5 μm or less. In a microstructure where the average grain size is less than 1 μm, unrecrystallized grains may be present, and from the viewpoint of maintaining stable and good bendability, it is advantageous for the average grain size to be 1 μm or more. The manufacturing process described later, which involves two solution treatments, is effective in refining the grain size. Note that the cutting method specified in JIS H0501-1986 states that "the average value of the cutting length (mm) shall be used for indication," but since the target grain size in this invention is very small compared to this specified unit of indication, measurements conforming to the method of the said standard are performed in an observation field with a higher magnification to determine the average grain size in μm units.

[0028] [Number density of coarse precipitate particles] Reducing the amount of coarse precipitates is extremely effective in improving fatigue characteristics. In the present invention, the number density of coarse precipitate particles having a major axis of 1.0 μm or more on an observation plane parallel to the plate surface is 1.0 × 10 5 particles / mm 2 or less, and is defined as the tissue state. The number density of coarse precipitate particles is more effective at 8.5 × 10 4 particles / mm 2 or less. In particular, when the number density of coarse precipitate particles is 8.5 × 10 4 particles / mm 2 or less, and the above-mentioned average crystal grain size is 15 μm or less, it is more advantageous for improving fatigue characteristics. Although it is preferable that the number of coarse precipitate particles is as small as possible, it is difficult to completely prevent the generation of coarse precipitate particles during production. Usually, the number density of coarse precipitate particles is 5.0 × 10 2 particles / mm 2 or more. The number density of coarse precipitate particles can be determined by the following method.

[0029] (Method for determining the number density of coarse precipitate particles) For the observation plane obtained by electrolytically polishing the plate surface under the following electrolytic polishing conditions to dissolve only the Cu matrix of the copper alloy sheet and expose the precipitate particles, observe with a FE-SEM (field emission scanning electron microscope) at an acceleration voltage of 15 kV and a magnification of 5000 times. The value obtained by dividing the total number of precipitate particles having a major axis of 1.0 μm or more observed on the FE-SEM image by the total observation area (mm 2 ) is defined as the number density of coarse precipitate particles (particles / mm 2 ). After focusing the secondary electron image of the FE-SEM at a magnification of 5000 times, adjust the color tone with auto contrast. At this time, since the same field image may be burned by the electron beam and the color tone may change, the observation is performed in a field different from the field where auto contrast is performed. This is an operation to prevent the results of the precipitate number density from varying due to adjustment of the luminance threshold (threshold value) in the binarization process of the coarse precipitate described later. The total observation area is a total of 0.1 mm 2This concludes the procedure. For precipitate particles that extend beyond the observation field, if the portion visible within the observation field represents the entire particle, and its major axis is 1.0 μm or larger, it will be counted. Regarding the measurement of the major axis of precipitate particles, the SEM image (secondary electron image) can be binarized using image analysis software to identify the area where the precipitate particles are present, the contour of each precipitate particle can be approximated as an ellipse, and the length of the major axis of that ellipse (however, if the ellipse is a perfect circle, the diameter of that circle) can be used as the major axis.

[0030] (Electrolytic polishing conditions) • Electrolyte: A mixture of distilled water, phosphoric acid, ethanol, and 2-propanol in a volume ratio of 10:5:5:1. • Liquid temperature: 20℃ Voltage: 15V ·Electrolysis time: 20 seconds

[0031] [Spring limit value] The spring limit value will be measured using a method conforming to the moment test specified in JIS H3130:2018. While the standard states that "the test specimen shall be taken in the direction of rolling of the plate or strip," here, to evaluate under stricter criteria, a test specimen with its longitudinal direction perpendicular to the rolling direction (TD) will be used. The direction perpendicular to rolling is the direction perpendicular to both the rolling direction and the plate thickness direction. Except for using a test specimen with its longitudinal direction perpendicular to rolling, the moment test for alloy number C1990 as described in JIS H3130:2018 will be adopted. As a result of the investigation, a spring limit value of 400 MPa or higher is advantageous for achieving high reliability in electrically conductive spring components that may be subjected to complex bending shapes. A spring limit value of 550 MPa or higher is more effective, and it can be adjusted to 700 MPa or higher. Note that the spring limit value is usually 1000 MPa or lower.

[0032] [Tensile strength] The tensile strength in the rolling direction (LD) of the copper alloy sheet material of the present invention is preferably 850 MPa or higher, and more preferably 880 MPa or higher. It is also possible to adjust the strength level so that the tensile strength in the rolling direction is 1000 MPa or higher. There is no particular upper limit to the tensile strength, but it may be adjusted to a range of, for example, 1400 MPa or less, or to a range of 1200 MPa or less.

[0033] [KAM value] To achieve the excellent spring limit value defined in this invention, it is preferable that the KAM value does not become too high. The KAM value is one of the indicators that can evaluate the lattice strain within the crystal grains. As a result of the study, in the copper alloy plate material of this invention, it is preferable that the KAM value is 3.00° or less when the boundary of the crystal orientation difference of 15° or more is considered as the grain boundary in the measurement by EBSD (electron backscatter diffraction) on an observation surface parallel to the plate surface with a step size of 0.1 μm. As long as a sufficient spring limit value is obtained, the lower limit of the KAM value is not particularly limited, but it is usually sufficient to adjust it within the range of 0.20° or more. From the viewpoint of an excellent spring limit value and manufacturability, it is more preferable that the KAM value is in the range of 0.45 to 2.00°. The KAM value can be determined by the following method.

[0034] (How to calculate the KAM value) The plate surface (rolled surface) of the plate material sample to be measured is buffed and polished, and then an observation surface is obtained by ion milling to make it smooth. Within this observation surface, observation areas with a field of view corresponding to an observation magnification of 2000x (for example, five rectangular areas of 45 μm in the direction perpendicular to rolling × 60 μm in the rolling direction) are randomly set, and crystal orientation data is collected by irradiating these observation areas with an electron beam using EBSD (electron backscatter diffraction) with a step size of 0.1 μm. Based on this data, the KAM (Kernel Average Misorientation) value is calculated using EBSD data analysis software, assuming that the boundary where the crystal orientation difference between adjacent measurement points is 15° or more is considered a grain boundary. The KAM value corresponds to measuring the crystal orientation difference between adjacent spots (hereinafter referred to as "adjacent spot orientation difference") for electron beam irradiation spots arranged at a pitch of 0.1 μm, extracting only the measured values ​​of adjacent spot orientation differences that are less than 15°, and calculating their average value. In calculating the KAM value, twinning boundaries are also considered grain boundaries.

[0035] [conductivity] Considering the applications of Cu-Ti-Al copper alloy sheet materials, a conductivity of 10.0% IACS or higher is desirable. While there is no particular upper limit to the conductivity, it is usually sufficient to adjust it within a range of 20.0% IACS or less.

[0036] [Bendability] Bending is often involved when processing materials into electrical components and the like. Considering the applications of Cu-Ti-Al alloy sheets, if the material has bendability such that the ratio of the minimum bending radius MBR to the sheet thickness t (MBR / t), as measured by a BW (Bad Way) bending test according to the Japan Copper Association Technical Standard JCBA T307:2007, is 2.0 or less, then high reliability can be obtained when processing into many electrical and heat dissipation components. It is more preferable that the MBR / t in BW be 1.0 or less, and even more preferable that it be 0.7 or less. It is also possible to obtain a material with an MBR / t in BW of 0.0 (no cracking in tight bending). BW (Bad Way) means that the bending axis is parallel to the rolling direction.

[0037] Furthermore, JCBA T307:2007 states that "This standard applies to the evaluation of the bendability of copper and copper alloy sheets and strips with a thickness of 0.1 mm or more and 0.8 mm or less." According to the inventors' studies, it was confirmed that even for Cu-Ti-Al copper alloy sheets with a thickness of less than 0.1 mm, the bendability can be evaluated by the W bending test using the method described in the said standard. Therefore, in this invention, the W bending test method using BW as shown in JCBA T307:2007 is extended to cases where the sheet thickness is less than 0.1 mm (for example, 0.02 mm or more and less than 0.1 mm) and applied as is.

[0038] [Fatigue characteristics] In electrically conductive spring components that may be bent into complex shapes, to achieve high reliability, a fatigue limit of 10 at a load stress of 450 MPa should be obtained in a cantilever resonance fatigue test using a specimen whose longitudinal direction is perpendicular to the rolling direction (TD). 7 It is larger than the cycle, i.e., 1.0 × 10⁻⁶ 7 It is preferable that "fatigue" does not occur during the cycle, 2.0 × 10 7 It is preferable that "fatigue" does not occur during the cycle. Note that typically, 5.0 × 10 8 Fatigue occurs within the following cycles: 3.0 x 10 8 Fatigue can occur in less than one cycle. "Fatigue" can be determined by monitoring the decrease in resonant frequency associated with a decrease in Young's modulus.

[0039] [density] Since the atomic weight order of Cu, Ti, and Al is Cu > Ti > Al, increasing the Al content is the most effective way to reduce the density (specific gravity) of Cu-Ti-Al copper alloys, and the Ti content also has a significant effect. According to the present invention, the density at 20°C is 8.53 g / cm³. 3 The following reductions are possible: In Cu-Ti-Al copper alloy sheet materials, the density can be reduced to 8.53 g / cm³ while maintaining good strength, bendability, conductivity, fatigue properties, and spring limit. 3Reducing it to the following levels was difficult with conventional technology. Note that there is no particular lower limit to the density, but for example, 7.80 g / cm³. 3 You should adjust it within the above range.

[0040] [Manufacturing method] The copper alloy sheet material described above can be manufactured, for example, by the following manufacturing process. Melting and casting → Slab heating → Hot working → Rough cold rolling → First solution treatment → First intermediate cold rolling → Second solution treatment → Second intermediate cold rolling → Aging treatment Although not mentioned in the above process, surface machining is performed as needed after hot working, and pickling, polishing, or further degreasing is performed as needed after each heat treatment. The following describes each of the above processes.

[0041] [Melting and Casting] Cast slabs with the chemical composition specified in this invention can be produced using a crucible furnace or the like. To prevent oxidation of Ti and Al, it is preferable to carry out the process in an inert gas atmosphere or a vacuum melting furnace.

[0042] [Slab heating] The slab heating before hot working can be carried out, for example, by holding it at 900-1000°C for 0.5-5 hours.

[0043] [Hot working, cold rolling] The method of hot working is not particularly limited. Typically, hot rolling or hot forging is used. In the case of hot rolling, the total hot rolling ratio can be, for example, 60-99%. After the hot working is completed, it is preferable to rapidly cool the material by water cooling or the like. Next, cold rolling is performed. Cold rolling at this stage is referred to as "rough cold rolling" in this specification. The rolling ratio in rough cold rolling can be, for example, 50-99%. In this way, an intermediate product sheet material for the first solution treatment can be obtained. Here, the rolling ratio is expressed by the following equation (1) (the same applies to each of the following processes). Rolling ratio (%) = 100 × (t0 - t1) / t0 ... (1) t0: Plate thickness before rolling (mm) t1: Thickness of the sheet after rolling (mm)

[0044] [First solution treatment] The above-mentioned intermediate product sheet material is subjected to a first solution treatment. In this solution treatment, the strain introduced during hot working and rough cold rolling is used to recrystallize the material, and coarse grain boundary reaction type precipitates and granular precipitates generated after casting or during hot working are sufficiently dissolved. If the solid solution of precipitates is insufficient at this first solution treatment stage, the precipitates will remain until the final process, and the desired properties cannot be obtained. In the first solution treatment, it is advantageous to introduce a large amount of thermal energy to prioritize solid solution. In this case, recrystallized grain growth is likely to occur, but this is not a problem as the grains will be refined in the subsequent second solution treatment. The first solution treatment is performed under conditions of holding at a temperature range of 800 to 900°C for 20 to 600 seconds.

[0045] [First Intermediate Cold Rolling] Cold rolling performed on material after the first solution treatment is called the first cold rolling. The purpose of the first cold rolling is to reduce the thickness of the sheet and to introduce strain. If the introduction of strain is insufficient, sufficient nucleation sites for recrystallization cannot be secured in the subsequent second solution treatment, making grain refinement difficult. In the first intermediate cold rolling, the rolling ratio should be 70% or more. A rolling ratio of 85% or more is more effective, and 90% or more is even more effective. There is no particular upper limit on the rolling ratio, but it is usually sufficient to set it within the range of 99% or less, depending on the capacity of the cold rolling mill.

[0046] [Second solution treatment] After the first intermediate cold rolling, the material has already undergone sufficient solid solution of precipitates, and strain has been introduced into the matrix (metal base material) crystals. A second solution treatment is then performed on this sheet material with this microstructure. In this solution treatment, the strain introduced in the first intermediate cold rolling is used to induce new recrystallization at many locations, thereby refining the crystal grains. The main objective is not solid solution of precipitates, but rather grain refinement through recrystallization, so the permissible upper limit of the heating temperature is lower than in the first solution treatment. Specifically, the treatment is performed under conditions of holding the temperature in the range of 750 to 860°C for 10 to 300 seconds. If the heating temperature is too high, grain growth accompanied by grain boundary movement between recrystallized grains is likely to occur, which may result in coarsening of the crystal grains. If the heating temperature is too low, precipitation is more likely to occur instead of recrystallization, making it difficult to generate sufficient fine precipitates in the aging treatment described later.

[0047] [Second Intermediate Cold Rolling] Cold rolling applied to materials after the second solution treatment is called second intermediate cold rolling. In second intermediate cold rolling, a moderate amount of strain is introduced to promote the formation of fine precipitates within the crystal grains during the subsequent aging treatment. This strain also contributes to improving strength. If too much strain is introduced, excessive strain will remain after the aging treatment, which can ultimately lead to insufficient improvement in bendability and spring limit. In second intermediate cold rolling, the rolling ratio is set in the range of 15-50%. It may also be controlled within the range of 15-35%.

[0048] [Statute of limitations] After the second intermediate cold rolling, the material is subjected to an aging treatment with specified conditions for both the heating and cooling processes. In the heating and holding process, the maximum temperature T0 (°C) is set to 320°C or higher and 450°C or lower, and the material is held for 5 to 20 hours in a holding temperature range of [T0-10°C] or higher and T0 or lower. The start of this holding is when the temperature first reaches [T0-10°C], and the end is when the temperature first drops below [T0-10°C] from the holding temperature range of [T0-10°C] or higher and T0 or lower. During the heating and holding process, the energy of the strain introduced in the second intermediate cold rolling is used to generate fine precipitates from many sites within the crystal grains, improving strength, conductivity, and fatigue properties. If the maximum temperature T0 is too high, the size of the fine precipitates increases and the number density decreases, which tends to result in insufficient improvement in strength, bendability, and fatigue properties. If the maximum temperature T0 is too low, or if the holding time within the above holding temperature range is too short, the amount of precipitate formed will be insufficient, resulting in inadequate improvement in strength and conductivity.

[0049] During the cooling process of the aging treatment, in the temperature range from the holding temperature range to 300°C, the excessive growth of precipitate particles generated in the holding temperature range is suppressed while new precipitates are generated as the temperature cools, and residual stress is reduced. The residence time in the temperature range up to 300°C, while ensuring a sufficient amount of new precipitates are generated during cooling, should be as short as possible. Specifically, it is effective to control the average cooling rate in the temperature range from [T0-10°C] to 300°C (hereinafter, this temperature range may be referred to as the "first cooling temperature range") to 30-60°C / h. If the average cooling rate in the first cooling temperature range is too fast, the precipitation reaction accompanying the cooling may not progress sufficiently, resulting in insufficient improvement in conductivity. Also, the reduction in residual stress may be insufficient, resulting in insufficient improvement in the spring limit value. If the average cooling rate in the first cooling temperature range is too slow, coarse precipitates may increase, leading to a decrease in fatigue properties.

[0050] During the cooling process of aging treatment, residual stress should be reduced in the temperature range below 300°C. Therefore, it is effective to extend the stay time in the temperature range below 300°C as long as productivity allows. Specifically, it is effective to control the average cooling rate in the temperature range from 300°C to 150°C (hereinafter, this temperature range may be referred to as the "second cooling temperature range") to 20°C / h or less. If the average cooling rate in the second cooling temperature range is too fast, the reduction of residual stress may be insufficient, resulting in an inadequate improvement in the spring limit value. Since excessively slowing the average cooling rate in the second cooling temperature range leads to a decrease in productivity, it is usually sufficient to set the average cooling rate in the second cooling temperature range to a range of 10°C / h or higher.

[0051] If cold rolling or annealing is performed after the aging treatment described above, the microstructure formed by the aging treatment may be damaged, making it impossible to achieve a combination of good strength, bendability, conductivity, fatigue properties, and spring limit. Therefore, it is desirable to make the aging treatment described above the final step in the manufacturing process of copper alloy sheets, as it involves processing and thermal history. The final plate thickness can be, for example, in the range of 0.02 to 0.50 mm.

[0052] [Electronic components, power supply components, heat dissipation components] As described above, the copper alloy sheet material of the present invention possesses excellent strength, bendability, conductivity, fatigue characteristics, and spring limit, and also has reduced density (specific gravity). Therefore, electronic equipment components, conductive components, and heat dissipation components formed using this sheet material through processes including press working and bending meet the demands for high functionality in recent mobile terminals and automotive electronic equipment. [Examples]

[0053] Copper alloys with the chemical composition shown in Table 1 were melted and cast. The resulting slabs (50 mm thick) were heated at the temperatures and times shown in Tables 2 and 3, then hot-rolled to the plate thicknesses indicated in Tables 2 and 3, and water-cooled. After hot-rolling, the surface oxide layer was removed by mechanical polishing (surface grinding), and each hot-rolled material was cold-rolled to the plate thickness indicated in the "Rough Cold Rolling" column of Tables 2 and 3.

[0054] Subsequently, with the exception of some examples (Comparative Examples No. 57-61), the first solution treatment, first intermediate cold rolling, second solution treatment, second intermediate cold rolling, and aging treatment were performed in the order described above under the conditions shown in Tables 2 and 3. The aging treatment was carried out in a batch-type heat treatment furnace under a nitrogen atmosphere. The "-" (hyphen) in Tables 2 and 3 indicates that a process was omitted. In No. 57, after rough cold rolling, straightening with a tension leveler was performed at a heating rate of 20°C / s, a target temperature of 200°C, and a tension of 120 MPa, after which cold rolling and solution treatment were performed, and cold rolling before aging treatment was omitted. In No. 58, the second intermediate cold rolling was omitted. In Nos. 59 and 60, intermediate cold rolling was not performed, and the material that had undergone one solution treatment was subjected to aging treatment. In No. 61, the second solution treatment and second intermediate cold rolling were omitted.

[0055] The aging treatment was carried out in a batch-type heat treatment furnace under a nitrogen atmosphere. After heating, the material was maintained at the maximum temperature T0 (°C) as shown in Tables 2 and 3, and then cooling was started. That is, after reaching the maximum temperature T0, the temperature was controlled to a constant level until cooling began. The "time" listed in the "Heating and Holding" column of Tables 2 and 3 is the time the material temperature was held in the temperature range of [T0-10°C] or higher and T0 or lower. Here, the material was maintained at a constant temperature T0 until cooling began, so the "time" listed in the "Heating and Holding" column of Tables 2 and 3 includes the time required to reach T0 from [T0-10°C] before the heating was completed, and the time required to reach [T0-10°C] from T0 after cooling began. During the cooling process, the average cooling rate in the first cooling temperature range from [T0-10°C] to 300°C and the average cooling rate in the second cooling temperature range from 300°C to 150°C were controlled as shown in Tables 2 and 3.

[0056] Except for a few examples (Comparative Examples No. 56-61), the test materials were sheet materials that had undergone the aging treatment described above. In Nos. 56-61, the test materials were sheet materials obtained by performing finish cold rolling or further low-temperature annealing under the conditions described in Table 3 after the aging treatment. Tables 2 and 3 show the thickness of the final obtained sheet materials (test materials). The following investigations were conducted on each test material. The density (specific gravity) was measured using block samples cut from the material after the slab heating stage.

[0057] (Elemental analysis) Oxygen (O) and nitrogen (N) were quantified using an oxygen-nitrogen-hydrogen analyzer (LECO, ONH-836), hydrogen (H) was quantified using a hydrogen analyzer (Horiba, EMGA-921), carbon (C) and sulfur (S) were quantified using a carbon-sulfur analyzer (LECO, CS844), elements from the 2nd to 6th periods (excluding C, N, O, group 17 elements, group 18 elements, technetium (Tc), polonium (Po), and promethium (Pm)) were quantified using ICP-MS (Agilent, 7900), and fluorine (F), chlorine (Cl), and bromine (Br) were quantified using a combustion-ion chromatography apparatus (Thermo Scientific, DIONEX ICS-1600). These measurements allow for the quantification of virtually all elements that may be present in the copper alloy plate material. As a result, it was confirmed that all test materials in both the present invention example and the comparative example met the requirements that the total content of Ag, B, Co, Cr, Fe, Mg, Mn, Nb, Ni, P, S, Si, Sn, V, Zn, Zr, and rare earth elements was 3.00% or less, and the total content of elements other than Ti, Al, Ag, B, Co, Cr, Fe, Mg, Mn, Nb, Ni, P, S, Si, Sn, V, Zn, Zr, rare earth elements, and Cu was 0-0.50%. In all examples, the total content of elements other than Ti, Al, Ag, B, Co, Cr, Fe, Mg, Mn, Nb, Ni, P, S, Si, Sn, V, Zn, Zr, rare earth elements, and Cu was 0.10% or less.

[0058] (Average grain size) The surface of the test material was polished, and the surface, finished by electrolytic polishing using the electrolytic polishing conditions described in "Method for Determining the Number Density of Coarse Precipitate Particles" above, was etched to create an observation surface. This observation surface was observed with an optical microscope at a magnification of 1000x, and an observation image was obtained. Three straight lines parallel to the rolling direction were drawn, and the average grain size in the observation field was calculated by counting the number of grain boundaries cut by each line using the cutting method in accordance with JIS H0501-1986. This operation was performed on five randomly selected fields of view, and the arithmetic mean of the average grain sizes obtained in each field of view was adopted as the average grain size of the plate material. An OLYMPUS LEXT OLS4000 optical microscope was used.

[0059] (Number density of coarse precipitate particles) The number density of coarse precipitate particles was determined according to the method described above in "Method for determining the number density of coarse precipitate particles".

[0060] For measuring the major axis of the precipitate particles, Image J (National Institutes of Health (NIH), Version 1.52a) was used as the image analysis software. The analysis conditions using this software were as follows: On the "Set Scale" screen, which is displayed by sequentially selecting Analyze and Set Scale, the number of pixels representing the scale bar length of the captured FE-SEM image was measured and entered into Distance in pixels. Next, the scale bar length (μm) was entered into Known distance, the Pixel aspect ratio was set to 1.0, and the Unit of length to μm, so that the software could recognize the size of the precipitates. After that, on the "Resize Image Canvas" screen, the Width was set to 1280 pixels, Height to 950 pixels, and Position to Top-Center, and the image of the FE-SEM image portion excluding the scale bar was displayed. After setting the scale and removing the scale bar display, the "Threshold" screen, accessed by sequentially selecting Image, Adjust, and Threshold, inverted the brightness so that the pixel with the lowest brightness among all pixels had a brightness of 255 and the pixel with the highest brightness had a brightness of 0. The threshold was then set to a value that brought the percentage of pixels below that value to 5% of all pixels as close to 5% as possible, and the areas containing precipitate particles were binarized and identified. Subsequently, in the "Analyze Particles" screen of the same software, the area of ​​a single independent precipitate region was 0.1 μm². 2 To exclude particles smaller than a certain size, the Size was set to "0.10-Infinity". Furthermore, the Circularity was set to 0.00-1.00, and the "Fit Ellipse" option was checked in the "Set Measurements" screen. Particle analysis was then performed, and the number density of precipitate particles with a major axis (displayed under the item name "Major") of 1.0 μm or larger in that field of view was determined.

[0061] (KAM value) After buffing the plate surface of the sample cut from the test material, ion milling was performed to prepare the sample surface for EBSD (electron beam backscatter diffraction) measurement. The sample surface was observed using a FE-SEM (JEOL Ltd. JSM-7200F) under conditions of an acceleration voltage of 15kV and a magnification of 2000x. Crystal orientation data was collected using the EBSD method with a step size of 0.1μm for a rectangular measurement area of ​​45μm perpendicular to the rolling direction and 60μm in the rolling direction, using the EBSD device (Oxford Instruments, Symmetry) installed on the FE-SEM. Based on the crystal orientation data measured for the five measurement areas, the KAM value was determined according to the "Method for Determining KAM Values" described above. OIM-Analysis 7.3.1, manufactured by TSL Solutions Co., Ltd., was used as the EBSD data analysis software.

[0062] (Spring limit value) The spring limit was determined by performing a moment-type test on alloy number C1990 as described in JIS H3130:2018, using test specimens cut from the test material with their longitudinal direction perpendicular to the rolling direction (TD).

[0063] (Tensile strength) Tensile test specimens (JIS No. 5) were taken from each test material in the rolling direction (TD), and tensile tests were performed in accordance with JIS Z2241 for n=3 tests to measure the tensile strength. The average value of n=3 was taken as the performance value for the test material.

[0064] (conductivity) The conductivity of each test material was measured using the double-bridge and average cross-sectional area methods in accordance with JIS H0505.

[0065] (MBR / t with 90°W bend) The ratio MBR / t between the minimum bending radius (MBR) and the plate thickness (t) was determined by a W-bending test on a BW (Block Welding) plate in accordance with the Japan Copper Spinning Association (JCBA) technical standard J307:2007. The specimen size was 30 mm in the direction perpendicular to rolling and 10 mm in the direction of rolling. Bending tests were performed with progressively different bending radii, with n=3 tests conducted for each bending radius. The minimum bending radius at which no cracks were observed on the bent surface of all three specimens was defined as the MBR for that material. The presence or absence of cracks on the bent surface was determined according to JCBA T307:2007. For samples judged as "large wrinkles" based on the visual inspection of the bent surface, a sample was prepared by cutting perpendicular to the bending axis at the deepest wrinkled part, and the polished cross-section was observed under an optical microscope to check for cracks propagating into the plate thickness. If no such cracks were observed, it was determined that "no cracks were observed."

[0066] (Fatigue limit) A 3mm wide, 20mm long specimen was cut from the material, with the width direction being the rolling direction (LD) and the length direction being perpendicular to the rolling direction (TD). A cantilever resonance fatigue test was performed using a fatigue testing apparatus (RF-RT, manufactured by Nippon Techno Plus Co., Ltd.) at a load stress of 450 MPa. The change in resonance frequency was monitored during the test, and the number of cycles at which the resonance frequency reached 98% of the initial value was defined as the fatigue limit of the specimen. This procedure was performed on five specimens prepared from a single material, and the average of their fatigue limits was adopted as the fatigue limit of the material in question.

[0067] (density) Using a 10g block sample cut from the material after the slab heating stage, the density at room temperature (20°C) was measured by the Archimedes method (gravimetric method in water). The results are shown in Tables 4 and 5.

[0068] [Table 1]

[0069] [Table 2]

[0070] [Table 3]

[0071] [Table 4]

[0072] [Table 5]

[0073] All of the plate materials of the present invention, whose chemical composition and manufacturing conditions were strictly controlled according to the above-mentioned provisions, possessed high levels of strength, bendability, conductivity, fatigue characteristics, and spring limit, and also exhibited excellent density (specific gravity) reduction effects.

[0074] In contrast, the comparative example yielded the following results. No. 41 had insufficient Al content, resulting in inadequate reduction of density (specific gravity). Furthermore, the remaining coarse precipitates were not sufficiently eliminated, leading to poor fatigue properties. No. 42 had poor conductivity because its Al content was too high. No. 43 had insufficient titanium content, resulting in low strength and inadequate reduction in density (specific gravity). No. 44 had poor bendability because its titanium content was too high. In No. 45, the temperature of the first solution treatment was too low, resulting in insufficient solid solution formation of the precipitated phase. This is thought to have prevented sufficient precipitation of fine precipitates during the aging treatment, leading to low strength. Furthermore, the abundance of coarse precipitates resulted in poor fatigue properties. In No. 46, the temperature of the first solution treatment was too high, causing the crystal grains to coarse. As a result, sufficient grain refinement could not be achieved in the second solution treatment, leading to poor fatigue properties and bendability. In No. 47, the rolling ratio in the first intermediate cold rolling was too low, resulting in insufficient strain introduction. This led to variations in grain growth during the subsequent second solution treatment, where larger grains absorbed smaller ones, preventing grain refinement. As a result, it exhibited poor bendability and fatigue properties. In No. 48, the rolling ratio during the second intermediate cold rolling was too low, resulting in insufficient strain introduction. This led to insufficient formation of fine precipitates within the grains during the subsequent aging treatment, resulting in low strength. Furthermore, the insufficient strain during the aging treatment accelerated precipitation at the grain boundaries, leading to an increase in coarse precipitates and poor fatigue properties. In No. 49, the rolling ratio during the second intermediate cold rolling was too high, resulting in excessive strain introduction, a microstructure with a high KAM value, and a low spring limit value. In No. 50, the precipitation progressed insufficiently because the heating and holding temperature during the aging treatment was too low, resulting in low strength and conductivity. In No. 51, the low strength was likely due to the fact that the heating and holding temperature during the aging treatment was too high, resulting in insufficient formation of fine precipitates. In No. 52, the cooling rate in the first cooling temperature range during the aging treatment was too slow, resulting in the formation of many coarse precipitates during the cooling process and thus poor fatigue characteristics. In sample No. 53, the cooling rate in the first cooling temperature range during the aging treatment was too high, resulting in insufficient precipitation during the cooling process and poor conductivity. Furthermore, the removal of residual stress in the first cooling temperature range was insufficient, leading to a low spring limit. In case No. 54, the cooling rate in the second cooling temperature range during the aging treatment was too low, resulting in insufficient removal of residual stress during the cooling process and a low spring limit value. Because No. 55 did not contain aluminum, the reduction in density (specific gravity) was insufficient. Furthermore, the remaining coarse precipitates were not adequately eliminated, resulting in poor fatigue properties. In case No. 56, cold rolling was performed after aging treatment, so even after subsequent low-temperature annealing, the processing strain could not be sufficiently removed, resulting in a microstructure with a high KAM value and a low spring limit value. No. 57, lacking aluminum, suffered from insufficient density (specific gravity) reduction. The absence of a first solution treatment resulted in larger grain sizes and poor fatigue properties. The lack of cold rolling between the solution treatment and aging treatment likely led to insufficient formation of fine precipitates during aging, resulting in low strength. Despite the low strength, it exhibited relatively good bendability. The straightening process using a tension leveler likely resulted in increased tensile residual stress, leading to a low spring limit. No. 58 underwent cold rolling after aging treatment, but by performing a second solution treatment and omitting the second intermediate cold rolling, the increase in the KAM value was suppressed and the spring limit value was increased. However, because no aluminum was added, the reduction in density (specific gravity) was insufficient, and the remaining coarse precipitates were not sufficiently eliminated, resulting in poor fatigue properties. No. 59, lacking aluminum additive, suffered from insufficient density (specific gravity) reduction and incomplete elimination of coarse precipitates, resulting in poor fatigue properties. Cold rolling was performed after aging treatment, resulting in a microstructure with a high KAM value and a low spring limit. Because No. 60 did not contain aluminum, the reduction in density (specific gravity) was insufficient, and the remaining coarse precipitates were not adequately eliminated, resulting in poor fatigue properties. No. 61 had insufficient Al content, resulting in inadequate reduction of density (specific gravity). Furthermore, due to the low Al content, the high heating and holding temperature during aging treatment, and the slow cooling rate in the first cooling temperature range, a large amount of coarse precipitates were produced, resulting in poor fatigue properties.

Claims

1. In mass percent, Ti: 1.00–5.00%, Al: 0.50–3.00%, Ag: 0–0.30%, B: 0–0.30%, Co: 0–1.00%, Cr: 0–1.00%, Fe: 0–1.00%, Mg: 0–1.00%, Mn: 0–2.00%, Nb: 0–1.00%, Ni: 0–1.00%, P: 0–0.50%, S: 0–0.20%, Si: 0–0.50%, Sn: 0–2.00%, V: 0–1.00%, Zn: 0–3.00%, Zr: 0–1.00%, rare earth elements The composition has the following characteristics: Total: 0-3.00%, Total of Ag, B, Co, Cr, Fe, Mg, Mn, Nb, Ni, P, S, Si, Sn, V, Zn, Zr and rare earth elements: 3.00% or less, Total of elements other than Ti, Al, Ag, B, Co, Cr, Fe, Mg, Mn, Nb, Ni, P, S, Si, Sn, V, Zn, Zr, rare earth elements, and Cu: 0-0.50%, Remainder: Cu, with a mass ratio of Ti to Al content Ti / Al of 1.50 or more, and an average crystal grain size of 1-20 μm on an observation surface parallel to the plate surface using a cutting method conforming to JIS H0501-1986, and a number density of coarse precipitate particles with a major axis of 1.0 μm or more on an observation surface parallel to the plate surface of 1.0 × 10⁻¹⁶ ５ pieces / mm ２ A copper alloy sheet material having the following characteristics: a tensile strength of 850 MPa or more in the direction parallel to rolling, and a spring limit value of 400 MPa or more in the direction perpendicular to rolling.

2. The copper alloy plate material according to claim 1, wherein the Nb content is 0 to 0.50% by mass.

3. The copper alloy plate material according to claim 1, wherein, in measurements using EBSD (electron backscatter diffraction) on an observation surface parallel to the plate surface with a step size of 0.1 μm, the KAM value is 3.00° or less when boundaries with a crystal orientation difference of 15° or more are considered as crystal grain boundaries.

4. The copper alloy plate material according to claim 1, wherein the conductivity is 10.0% IACS or higher.

5. The copper alloy sheet material according to claim 1, wherein the ratio MBR / t of the minimum bending radius MBR (where no crack occurs) to the sheet thickness t, as determined by a W bending test in B.W. in accordance with the Japan Copper Alloy Association Technical Standard JCBA T307:2007, is 2.0 or less.

6. In a cantilevered resonance fatigue test using a specimen with its longitudinal direction perpendicular to the rolling direction, the fatigue limit at a load stress of 450 MPa was 10 ７ A copper alloy plate material according to claim 1, having a larger cycle.

7. Density is 8.53 g / cm³ ３ The copper alloy plate material according to claim 1, which is as follows:

8. An electronic component made using a copper alloy plate material as described in any one of claims 1 to 7.

9. An electrical component using a copper alloy plate material as described in any one of claims 1 to 7.

10. A heat dissipation component made using a copper alloy plate material as described in any one of claims 1 to 7.

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