Copper alloy sheet material, copper alloy sheet material for drawing, and drawn product

Abstract

Provided are a copper alloy sheet material which has exceptional drawing workability and from which it is possible to obtain a drawn product having exceptional dimensional accuracy, a copper alloy sheet material for drawing, and a drawn product having exceptional dimensional accuracy. This copper alloy sheet material has an alloy composition containing 1.00-5.00 mass% of Ni, 0.02-1.50 mass% of Si, and a total of 0-1.00 mass% of at least one element selected from the group consisting of Sn, Zn, Mg, Fe, and Cr, the balance being Cu and unavoidable impurities. The area ratio of a crystal orientation region within 20° from a {111} <112> orientation obtained by measurement performed using an EBSD method on a surface of the copper alloy sheet material is 3.0% or greater.

Description

Copper alloy sheets, copper alloy sheets for drawing and drawn products

[0001] The present disclosure relates to a copper alloy sheet material, a copper alloy sheet material for drawing, and a drawn product.

[0002] Cu-Ni-Si alloys have been attracting attention for their bending properties for connectors, and various improvements have been made through crystal orientation control. However, there have been few reports of Cu-Ni-Si alloys with excellent drawing properties.

[0003] For example, as a bending workability technique, Patent Document 1 describes a Cu-Ni-Si based copper alloy strip that has high strength and excellent bending workability, and further has small bending anisotropy, and is suitable as a copper alloy for electronic materials such as connectors. Such a Cu-Ni-Si based copper alloy strip contains predetermined amounts of Ni and Si, with the balance being Cu and unavoidable impurities. The X-ray diffraction intensity of three (hkl) planes measured by X-ray diffraction on the rolled surface of the copper-based alloy is (I （１１１） +I （３１１） ) / I （２２０） ≦2.0.

[0004] Furthermore, as a technique for drawing workability, a Cu—Ni—Si-based copper alloy sheet excellent in deep drawing workability and fatigue resistance is described in Patent Document 2. Such a Cu—Ni—Si-based copper alloy sheet contains predetermined amounts of Ni and Si, with the remainder being Cu and inevitable impurities, and has a Goss orientation density of 2.0 to 6.0% measured by an EBSD method using a scanning electron microscope equipped with an electron backscatter diffraction image system, an average KAM value of 0.9 to 1.5°, and a ratio (Lσ / L) of the total special grain boundary length Lσ of the special grain boundaries to the total grain boundary length L of the crystal grain boundaries of 60 to 70%.

[0005] However, when the crystal orientation of the surface of a Cu—Ni—Si-based copper alloy sheet material manufactured by a conventional standard process is measured by EBSD or X-ray, almost no crystal grains including the {111} plane, which is considered to be advantageous for drawing workability, are observed. Furthermore, in terms of X-ray diffraction intensity, the diffraction intensity from the {220} plane is much greater than the diffraction intensity from the other major crystal planes, the {111} plane, the {200} plane, and the {311} plane. As a result, such copper alloy sheet material has strong material anisotropy, which adversely affects various subsequent processing steps. Therefore, the Cu—Ni—Si-based copper alloy material of Patent Document 1 aims to improve bending workability by controlling the crystal orientation.

[0006] Furthermore, Patent Document 1 is an invention aimed at improving strength and bending workability, and does not consider drawing workability. Furthermore, the crystal orientations advantageous for bending workability and drawing workability are not the same, and it is thought that the Cu—Ni—Si-based copper alloy material of Patent Document 1 does not have excellent drawing workability.

[0007] Furthermore, although Patent Document 2 is an invention related to the improvement of deep drawing workability, the evaluation of drawing only determines whether deep drawing is possible, and does not mention the dimensional accuracy of the drawn product. Furthermore, Patent Document 2 controls the Goss orientation density to 2.0 to 6.0% by crystal orientation control, but does not control crystal grains containing the {111} plane, which is considered to be advantageous for drawing workability. Therefore, it is considered that the Cu-Ni-Si-based copper alloy material of Patent Document 2 has insufficient drawing workability. Furthermore, it is considered that the dimensional accuracy of the drawn product obtained by drawing the Cu-Ni-Si-based copper alloy material of Patent Document 2 is also insufficient.

[0008] JP 2006-9108 A JP 2012-122114 A

[0009] An object of the present disclosure is to provide a copper alloy sheet material that is excellent in drawing workability and from which a drawn product having excellent dimensional accuracy can be obtained, a copper alloy sheet material for drawing work, and a drawn product having excellent dimensional accuracy.

[0010] [1] A copper alloy sheet having an alloy composition containing 1.00 to 5.00 mass% Ni, 0.20 to 1.50 mass% Si, and a total of 0 to 1.00 mass% of at least one element selected from the group consisting of Sn, Zn, Mg, Fe, and Cr, with the balance being Cu and unavoidable impurities, wherein the area ratio of a region having a crystal orientation within 20° from the {111}<112> orientation, as measured by EBSD on the surface, is 3.0% or more. [2] The copper alloy sheet according to [1] above, wherein the area ratio of a region having a crystal orientation within 20° from the {100}<001> orientation, as measured by EBSD on the surface, is 4.5% or less. [3] A copper alloy sheet for drawing, wherein the copper alloy sheet according to [1] or [2] above is used for drawing. [4] A drawn product obtained by drawing the copper alloy sheet material according to the above [1] or [2]. [5] The drawn product according to the above [4], wherein the circularity I defined by the following formula (1) is 0.10 mm or less, where D (mm) is the maximum diameter and d (mm) is the minimum diameter at the edge of the drawn product. Circularity I (mm) = {D (mm) - d (mm)} / 2 Formula (1)

[0011] According to the present disclosure, it is possible to provide a copper alloy sheet material that is excellent in drawing workability and from which a drawn product having excellent dimensional accuracy can be obtained, a copper alloy sheet material for drawing work, and a drawn product having excellent dimensional accuracy.

[0012] The embodiments will be described in detail below.

[0013] The present inventors have conducted extensive research into the following.

[0014] In a copper alloy sheet, after drawing, a deformation texture corresponding to the structure before drawing develops. If the copper alloy sheet before drawing has strong in-plane anisotropy, the strain distribution after drawing becomes non-uniform, resulting in a problem of deterioration in the roundness of the drawn product, which is a sample after drawing.

[0015] In the case of Cu-Ni-Si-based copper alloy sheet, since the in-plane anisotropy of the Cu-Ni-Si-based copper alloy sheet is very strong, even if the Cu-Ni-Si-based copper alloy sheet is drawn without breaking, the roundness of the drawn product is very poor. Therefore, it was not possible to apply the drawn product to fine parts or precision parts that require strict dimensional accuracy, such as contact probes for semiconductor inspection.

[0016] Therefore, it has been found that by controlling the area ratio of a region having a predetermined alloy composition and lying within 20° from the {111}<112> orientation, as measured by EBSD on the surface, within a predetermined range, a copper alloy sheet has excellent drawing workability, and a drawn product obtained by drawing the copper alloy sheet has excellent dimensional accuracy. The present disclosure has been completed based on this finding.

[0017] The copper alloy sheet material of the embodiment has an alloy composition containing 1.00 mass% or more and 5.00 mass% or less of Ni, 0.20 mass% or more and 1.50 mass% or less of Si, and 0 mass% or more and 1.00 mass% or less of at least one element selected from the group consisting of Sn, Zn, Mg, Fe, and Cr in total, with the balance being Cu and unavoidable impurities, and the area ratio of the region with a crystal orientation within 20° from the {111}<112> orientation obtained by measurement of the surface by an EBSD method is 3.0% or more.

[0018] First, the alloy composition of the copper alloy sheet material will be described.

[0019] The copper alloy sheet material of the above embodiment has an alloy composition containing 1.00 mass% or more and 5.00 mass% or less of Ni, 0.20 mass% or more and 1.50 mass% or less of Si, and at least one element selected from the group consisting of Sn, Zn, Mg, Fe, and Cr in a total amount of 0 mass% or more and 1.00 mass% or less, with the balance being Cu and unavoidable impurities.

[0020] <Ni: 1.00% by mass or more and 5.00% by mass or less> When the Ni (nickel) content is 1.00% by mass or more, the copper alloy sheet can be strengthened. Furthermore, when the Ni content is 5.00% by mass or less, the decrease in electrical conductivity can be suppressed, and further, the generation of a coarse second phase, which is a compound of Ni and Si, can be suppressed, thereby improving drawing workability. The coarse second phase is likely to become the starting point of cracks during drawing. Therefore, the lower limit of the Ni content is 1.00% by mass or more, preferably 1.50% by mass or more, more preferably 2.00% by mass or more, and the upper limit is 5.00% by mass or less, preferably 4.50% by mass or less, more preferably 4.00% by mass or less.

[0021] <Si: 0.20 mass% or more and 1.50 mass% or less> When the Si (silicon) content is 0.20 mass% or more, the copper alloy sheet can be strengthened. Furthermore, when the Si content is 1.50 mass% or less, the decrease in electrical conductivity can be suppressed, and further, the generation of a coarse second phase, which is a compound of Ni and Si, can be suppressed, thereby improving drawing workability. Therefore, the lower limit of the Si content is 0.20 mass% or more, preferably 0.30 mass% or more, more preferably 0.50 mass% or more, and the upper limit is 1.50 mass% or less, preferably 1.10 mass% or less, more preferably 1.00 mass% or less.

[0022] <Copper alloy sheet minor components: 0% by mass or more and 1.00% by mass or less> To further improve the properties of the copper alloy sheet, the alloy composition of the copper alloy sheet further contains at least one element selected from the group consisting of Sn, Zn, Mg, Fe, and Cr in a total amount of 0% by mass or more and 1.00% by mass or less. That is, the alloy composition of the copper alloy sheet may or may not contain, in addition to the essential basic components Ni and Si, one or more elements selected from the group consisting of Sn, Zn, Mg, Fe, and Cr as optional minor components. When the alloy composition of the copper alloy sheet contains at least one of the above elements, the alloy composition contains at most 1.00% by mass of the at least one element. When the alloy composition contains more than 1.00% by mass of the above at least one element, it becomes difficult to control the crystal orientation of the copper alloy sheet, and the drawing workability and dimensional accuracy of the drawing workability of the copper alloy sheet are reduced.

[0023] <Sn: 0.10% by mass or more and 0.30% by mass or less> When the Sn (tin) content is 0.10% by mass or more, the stress relaxation resistance of the copper alloy sheet can be improved. When the Sn content is 0.30% by mass or less, the decrease in the electrical conductivity of the copper alloy sheet can be suppressed. Therefore, the Sn content is preferably 0.10% by mass or more and 0.30% by mass or less.

[0024] <Zn: 0.10% by mass or more and 0.50% by mass or less> When the Zn (zinc) content is 0.10% by mass or more, the adhesion and migration characteristics of the Sn plating can be improved. When the Zn content is 0.50% by mass or less, the decrease in the electrical conductivity of the copper alloy sheet can be suppressed. Therefore, the Zn content is preferably 0.10% by mass or more and 0.50% by mass or less.

[0025] <Mg: 0.10% by mass or more and 0.30% by mass or less> When the Mg (magnesium) content is 0.10% by mass or more, the stress relaxation resistance of the copper alloy sheet can be improved. When the Mg content is 0.30% by mass or less, a decrease in the electrical conductivity of the copper alloy sheet can be suppressed. Therefore, the Mg content is preferably 0.10% by mass or more and 0.30% by mass or less.

[0026] <Fe: 0.05% by mass or more and 0.30% by mass or less> When the Fe (iron) content is 0.05% by mass or more, grain growth after dynamic recrystallization during hot rolling [Step 3] described below can be suppressed, and roughness of the surface of the drawn product can be suppressed. When the Fe content is 0.30% by mass or less, the generation of coarse Fe-containing crystals during melting and casting [Step 1] described below is suppressed, thereby improving the drawing workability of the copper alloy sheet material. Coarse Fe-containing crystals are likely to become the starting point of cracks during drawing. For this reason, the Fe content is preferably 0.05% by mass or more and 0.30% by mass or less.

[0027] <Cr: 0.05% by mass or more and 0.30% by mass or less> When the Cr (chromium) content is 0.05% by mass or more, grain growth after dynamic recrystallization during hot rolling [Step 3] is suppressed, and surface roughness of the drawn product can be suppressed. When the Cr content is 0.30% by mass or less, the generation of coarse Cr-containing crystals during melting and casting [Step 1] is suppressed, thereby improving the drawing workability of the copper alloy sheet material. The coarse Cr-containing crystals are likely to become the starting point of cracks during drawing. For this reason, the Cr content is preferably 0.05% by mass or more and 0.30% by mass or less.

[0028] <Remainder: Cu and inevitable impurities> The remainder of the alloy composition of the copper alloy sheet material other than the above-mentioned components is Cu (copper) and inevitable impurities. Inevitable impurities refer to impurities at a level that are inevitably mixed in during the manufacturing process. Since the content of inevitable impurities can affect the properties of the copper alloy sheet material, it is preferable that the content of inevitable impurities is low. Examples of inevitable impurities include non-metallic elements such as S (sulfur), C (carbon), and O (oxygen), and elements such as Sb (antimony). Note that the upper limit of the content of inevitable impurities is preferably 500 ppm or less for each of the above elements, and preferably 2000 ppm or less in total for the above elements.

[0029] Next, the area ratio of the predetermined region of the copper alloy sheet material will be described.

[0030] The area ratio of a region having a crystal orientation within 20° from the {111}<112> orientation (hereinafter simply referred to as the {111}<112> orientation region), as measured by EBSD on the surface of the copper alloy sheet, is 3.0% or more. The surface of the copper alloy sheet refers to the sheet surface of the copper alloy sheet.

[0031] Here, the crystal orientations present on the surface of Cu—Ni—Si alloy sheets manufactured by a general process are mainly BR orientation {362}<853>, RD-Rotated-Cube (RDW) orientation {012}<100>, and S orientation {231}<346>. These crystal orientations are orientations far removed from {111} planes such as {111}<112> orientation, and crystal orientations other than these are difficult to form. On the other hand, it is widely known that the more the crystal orientations are concentrated in the {111} plane in the sheet surface direction, the less likely thinning of the sheet thickness occurs during drawing, and the better the drawing workability (e.g., Light Metals, Vol. 66, No. 11 (2016), pp. 582-588, Simultaneous Prediction of Bendability and Deep Drawability of Aluminum Alloy Sheets Using Crystal Orientation Distribution Function).

[0032] The present inventors have clarified that the {111}<112> orientation is particularly effective in improving the drawing workability of copper alloy sheets and the dimensional accuracy of drawn products obtained by drawing the copper alloy sheets. The inventors have succeeded in inventing a Cu—Ni—Si-based copper alloy sheet having high drawing workability and dimensional accuracy of drawn products by controlling the crystal orientation of the copper alloy sheet and growing the {111}<112> orientation in the sheet plane direction. The present inventors believe that the techniques of Patent Documents 1 and 2 described above cannot orient the {111}<112> orientation in the sheet plane direction, and therefore cannot obtain copper alloy sheets having excellent drawing workability and dimensional accuracy of drawn products.

[0033] In Cu-Ni-Si alloy sheets manufactured by a general process, the area ratio of the {111}<112> orientation region is approximately less than 2%. On the other hand, in the copper alloy sheet (Cu-Ni-Si alloy sheet) of the embodiment, by controlling the crystal orientation, the area ratio of the {111}<112> orientation region is 3.0% or more, preferably 6.0% or more. Furthermore, for example, from the viewpoint of suppressing excessive anisotropy, the area ratio of the {111}<112> orientation region is preferably 20.0% or less.

[0034] Furthermore, the area ratio of a region having a crystal orientation within 20° from the {100}<001> orientation (Cube orientation) (hereinafter simply referred to as the {100}<001> orientation region), obtained by measurement of the surface of the copper alloy sheet by an EBSD method, is preferably 4.5% or less.

[0035] Although the {100}<001> orientation is generally known to deteriorate drawing workability, a certain amount of {100}<001> orientation exists in Cu-Ni-Si alloy sheets manufactured by a general process. However, the inventors have found that excellent dimensional accuracy of drawn products can be maintained by setting the area ratio of the {100}<001> orientation region to 4.5% or less when the area ratio of the {111}<112> orientation region is set to 3.0% or more.

[0036] The area ratio of the {111}<112> orientation region and the area ratio of the {100}<001> orientation region can be obtained from crystal orientation analysis data calculated using analysis software (OIM Analysis, manufactured by TSL) from crystal orientation data continuously measured using an EBSD detector attached to a high-resolution scanning analytical electron microscope (JEOL Ltd., JSM-7001FA). "EBSD" stands for Electron Backscatter Diffraction, and the EBSD method is a crystal orientation analysis technique that utilizes reflected electron Kikuchi diffraction that occurs when an electron beam is irradiated on a copper alloy sheet material, which is a measurement sample, in a scanning electron microscope (SEM). "OIM Analysis" is analysis software that analyzes data measured by EBSD.

[0037] The measurement area is a mirror-finished surface of a copper alloy plate (plate surface) by electrolytic polishing. The measurement area is 800 μm × 800 μm (640,000 μm ２ The measurement is performed with a scan step size of 0.2 μm. For the atomic planes of the crystal grains having an angle of deviation of 20° or less from each ideal orientation ({111}<112> orientation or {100}<001> orientation), the area of ​​the atomic planes having each orientation is calculated and divided by the measured area to obtain the area ratio of the region of each orientation.

[0038] As described above, the copper alloy sheet material has excellent drawing workability and can give drawn products with excellent dimensional accuracy, and is therefore suitable as a copper alloy sheet material for drawing used in drawing.

[0039] A drawn product obtained by drawing a copper alloy sheet material, i.e., a drawn product obtained by drawing a copper alloy sheet material, is suitably used for connectors for electronic devices or vehicles, switches, sockets, shield cases, shield cans, camera module cases, vibration device cases, heat dissipation parts for liquid crystal and organic EL displays, contact probes for semiconductor inspection, battery cases for lithium ion batteries, etc.

[0040] Furthermore, for a drawn product obtained by drawing a copper alloy sheet material, when the maximum diameter at the edge of the drawn product is D (mm) and the minimum diameter is d (mm), the roundness I defined by the following formula (1) is preferably 0.10 mm or less.

[0041] Circularity I (mm) = {D (mm) - d (mm)} / 2 Formula (1)

[0042] The smaller the roundness of a drawn product, the better. However, due to the presence of anisotropy in actual metal materials, it is difficult to obtain a drawn product in which the maximum diameter D and the minimum diameter d at the edge of the drawn portion are the same, i.e., the roundness I is 0. Therefore, specifications must be determined to meet the required dimensions of the component, and processing must be performed to reduce the roundness I. However, there is a limit to how much roundness can be improved by processing technology alone, and it is further required to select an appropriate material that is less likely to produce ears. Generally, the roundness I of the edge is often designed to be within a range of 0.10 mm or more and 0.20 mm or less, so the roundness I of the drawn product obtained by drawing the copper alloy sheet material of the embodiment is preferably 0.10 mm or less.

[0043] Next, a method for producing the copper alloy sheet material of the above embodiment will be described. The ingot having the above alloy composition obtained by melting and casting [Step 1] is subjected to reheating [Step 2], hot rolling [Step 3], first intermediate annealing [Step 4], second intermediate annealing [Step 5], first cold rolling [Step 6], solution heat treatment [Step 7], aging heat treatment [Step 8], second cold rolling [Step 9], and low-temperature annealing [Step 10] in this order to produce the copper alloy sheet material of the above embodiment.

[0044] In the melting and casting process [Step 1], alloy components are melted and cast to obtain a copper alloy ingot having the above alloy composition. For example, the melting is carried out in air using a high-frequency melting furnace. The types of alloy components and casting conditions are appropriately set.

[0045] In the reheating [step 2] performed after the melting and casting [step 1], the copper alloy ingot is subjected to a homogenizing heat treatment by holding it at a predetermined temperature in a reheating furnace for a predetermined time. In the reheating [step 2], the copper alloy ingot is heat-treated at a temperature in the range of 900°C to 1050°C for 1 hour to 10 hours. If the heat treatment temperature is less than 900°C, dynamic recrystallization does not occur sufficiently in the subsequent hot rolling [step 3], resulting in a non-uniform structure. If the heat treatment temperature is more than 1050°C, the grain boundaries are weakened, and cracks are likely to occur in the hot rolling [step 3].

[0046] Hot rolling [Step 3] is performed immediately after the end of reheating [Step 2]. Hot rolling [Step 3] may be performed under conditions that involve dynamic recrystallization. For example, hot rolling is performed between the reheating temperature and 700°C so that the reduction ratio calculated from the thickness before the start of rolling and the thickness after the roll pass completed by the time 700°C is reached is 50% or more. If dynamic recrystallization does not occur sufficiently, a non-uniform structure is likely to result. The temperature during hot rolling can be measured with a radiation thermometer. Furthermore, after hot rolling [Step 3], facing, for example, of 1 to 5 mm, may be performed depending on the oxidation state of the surface.

[0047] The processing rate (rolling reduction) in this specification is a value obtained by subtracting the cross-sectional area after rolling from the cross-sectional area before rolling, dividing the value by the cross-sectional area before rolling, and multiplying the result by 100, expressed as a percentage, and is expressed by the following formula (2).

[0048] Processing rate = {([cross-sectional area before rolling] - [cross-sectional area after rolling]) / [cross-sectional area before rolling]} × 100 (%) Formula (2)

[0049] In the first intermediate annealing [Step 4] performed after the hot rolling [Step 3], heat treatment is performed at a temperature of 700°C to 1000°C for 30 minutes to 2 hours. By growing crystal grains through heat treatment in the above temperature range above the recrystallization temperature, the anisotropy of the rolling texture obtained in the subsequent first cold rolling [Step 6] is weakened. If the heat treatment temperature of the first intermediate annealing [Step 4] is less than 700°C, crystal grain growth becomes insufficient and the anisotropy of the copper alloy sheet material increases, resulting in a decrease in the drawability of the copper alloy sheet material. Therefore, the heat treatment temperature of the first intermediate annealing [Step 4] is preferably 800°C or higher. Furthermore, since a heat treatment temperature of the first intermediate annealing [Step 4] exceeding 1000°C may result in partial melting of the material, the heat treatment temperature of the first intermediate annealing [Step 4] is preferably 950°C or lower. This step is particularly important for controlling the area ratio of the region with the {111}<112> orientation and the area ratio of the region with the {100}<001> orientation.

[0050] In the second intermediate annealing [step 5] performed after the first intermediate annealing [step 4], heat treatment is performed at a temperature of 450°C to 600°C for 30 minutes to 2 hours. ２ Precipitation of Si precipitates changes the solid solution concentration of elements and further generates a pinning effect on the crystal grains. As a result, the development of a specific crystal orientation can be suppressed in the rolling texture obtained in the first cold rolling [Step 6] and the recrystallization texture obtained in the solution heat treatment [Step 7], which are performed subsequently. Coarsening the crystal grains in the first intermediate annealing [Step 4] has the effect of weakening the development of the rolling texture. In addition to this effect, Ni ２ The aging precipitation of Si can further weaken the development of the rolling texture, which facilitates the formation of {111}<112> planes in the sheet surface direction during the solution heat treatment [Step 7] described below. This step is particularly important for controlling the area ratio of the {111}<112> orientation domain and the area ratio of the {100}<001> orientation domain.

[0051] After the second intermediate annealing [Step 5], a first cold rolling [Step 6] is performed. In the first cold rolling [Step 6], cold rolling is performed while adjusting the working ratio in the range of 65.0% or more and 99.9% or less depending on the plate thickness of the copper alloy plate material as a final product.

[0052] In the solution heat treatment [step 7] performed after the first cold rolling [step 6], the copper alloy sheet is held at 700°C or higher and 1000°C or lower for 10 to 60 seconds, followed by cooling. The final crystal orientation of the copper alloy sheet is mainly determined in this step. The crystal orientation obtained in this step is significantly different when the first intermediate annealing [step 4] and the second intermediate annealing [step 5] are performed compared to when they are not performed. If the solution heat treatment temperature is less than 700°C and / or the holding time is less than 10 seconds, precipitation strengthening in the subsequent aging heat treatment [step 8] is insufficient, resulting in a decrease in the strength of the copper alloy sheet. If the solution heat treatment temperature is higher than 1000°C and / or the holding time is longer than 60 seconds, the crystal grain size becomes coarse, resulting in a significant change in the area ratio of the crystal orientation. As a guideline for the conditions of this step, conditions in which the average crystal grain size is in the range of 5 μm to 30 μm are appropriate.

[0053] In the aging heat treatment [Step 8] performed after the solution heat treatment [Step 7], the temperature is maintained at 400°C or higher and 600°C or lower for 1 hour to 10 hours. If the temperature is lower than 400°C and / or the holding time is shorter than 1 hour, precipitation strengthening is not achieved, the strength of the copper alloy sheet material is reduced, and the electrical conductivity of the copper alloy sheet material is also reduced. If the temperature is higher than 600°C, the crystal grain size becomes coarse, and the area ratio of each crystal orientation may change significantly. Furthermore, if the holding time is longer than 10 hours, the precipitates become coarse, precipitation strengthening is not achieved, and the strength of the copper alloy sheet material is reduced.

[0054] In the second cold rolling [Step 9] performed after the aging heat treatment [Step 8], cold rolling is performed at a working ratio of 5% to 30%. If the working ratio is less than 5%, the effect of increasing the strength of the copper alloy sheet is small. If the working ratio is more than 30%, the crystal orientation developed in the previous steps changes significantly, and the {111}<112> orientation decreases.

[0055] In the low-temperature annealing [step 10] performed after the second cold rolling [step 9], a heat treatment is performed by holding the temperature at 200°C or higher and 600°C or lower for 10 seconds to 30 minutes, and then cooling to room temperature.

[0056] According to the embodiment described above, by controlling the area ratio of the region having a predetermined alloy composition and lying within 20° from the {111}<112> orientation, which is obtained by measuring the surface using the EBSD method, within a predetermined range, the copper alloy sheet has excellent drawing workability, and a drawn product obtained by drawing the copper alloy sheet can have excellent dimensional accuracy.

[0057] Although the embodiments have been described above, the present invention is not limited to the above embodiments, but includes all aspects encompassed by the concept and scope of the claims of the present disclosure, and can be modified in various ways within the scope of the present disclosure.

[0058] Next, examples and comparative examples will be described, but the present disclosure is not limited to these examples.

[0059] (Examples 1 to 23 and Comparative Examples 1 to 12) In melting and casting [step 1], each component was melted in the atmosphere using a high-frequency melting furnace and cast using a metal mold to obtain a copper alloy ingot having the copper alloy composition shown in Table 1. Subsequently, the copper alloy ingot is subjected to reheating [step 2] in which heat treatment is performed for 1 hour to 10 hours at a temperature range of 900 ° C. to 1050 ° C., hot rolling with dynamic recrystallization immediately after the completion of reheating [step 2] [step 3], first intermediate annealing [step 4] under the conditions shown in Table 2, second intermediate annealing [step 5] under the conditions shown in Table 2, first cold rolling [step 6] at a working ratio of 65.0% to 99.9%, solution heat treatment [step 7] under the conditions shown in Table 2, aging heat treatment [step 8] at 400 ° C. to 600 ° C. for 1 hour to 10 hours, second cold rolling [step 9] in which cold rolling at a working ratio of 5% to 30% is performed, and a low-temperature annealing [step 10] in which the copper alloy ingot is cooled to room temperature. A copper alloy sheet having a thickness of 0.20 mm was obtained by sequentially performing the following steps. The underlined parts in Table 1 and Table 3 described below are outside the scope of the embodiment.

[0060]

[0061]

[0062] [Measurements and Evaluations] The copper alloy sheets obtained in the above Examples and Comparative Examples were subjected to the following measurements and evaluations. The results are shown in Table 3.

[0063] [1] Area ratio of the {111}<112> orientation region and the {100}<001> orientation region The area ratio of the {111}<112> orientation region and the area ratio of the {100}<001> orientation region were obtained from crystal orientation analysis data calculated using analysis software (TSL, OIM Analysis) from crystal orientation data continuously measured using an EBSD detector attached to a high-resolution scanning analytical electron microscope (JEOL Ltd., JSM-7001FA). The measurement area was a surface (plate surface) of a copper alloy sheet that had been mirror-finished by electrolytic polishing. The measurement area was 800 μm × 800 μm (640,000 μm ２ The measurements were performed with a scanning step size of 0.2 μm. For the atomic planes of the crystal grains having a deviation angle of 20° or less from each ideal orientation ({111}<112> orientation or {100}<001> orientation), the area of ​​the atomic planes having each orientation was calculated, and the area was divided by the measured area to obtain the area ratio of the region of each orientation.

[0064] [2] Circularity I Circularity was used as an index of drawing workability. Circularity I was calculated using the above formula (1) based on JIS B 0621-1984. Specifically, a blank with a diameter of 40 mm was made by press punching, and a copper alloy sheet with a thickness of 0.20 mm was subjected to a single cylindrical drawing process using the blank with a punch with a diameter of 20 mm to obtain a drawn product. The punch shoulder radius was 1 mm. Furthermore, before processing, a lubricating oil (R303P) was applied to the surface of the copper alloy sheet. The edge of the drawn product was projected using a projector, and the maximum diameter D and minimum diameter d at the edge of the drawn product were measured, and the circularity I was calculated using formula (1). The evaluation of circularity was classified according to the following criteria. Good and fair were considered acceptable, and poor was considered unacceptable.

[0065] Good: Circularity I was 0 mm or more and 0.05 mm or less. Fair: Circularity I was more than 0.05 mm and 0.10 mm or less. Poor: Circularity I was more than 0.10 mm.

[0066]

[0067] As shown in Tables 1 to 3, in Examples 1 to 23, the copper alloy sheets had a predetermined alloy composition, and the area ratio of the region within 20° from the {111}<112> orientation was controlled within a predetermined range, so that the copper alloy sheets had excellent drawing workability and were able to produce drawn products with excellent dimensional accuracy. On the other hand, in Comparative Examples 1 to 12, at least one of the alloy composition and the area ratio of the region within 20° from the {111}<112> orientation was outside the predetermined range, so that the copper alloy sheets had poor drawing workability and the drawn products had poor dimensional accuracy.

[0068] Specifically, in Examples 1 to 13, which had the same alloy composition, by performing each step under appropriate conditions, the area ratio of the {111}<112> orientation region was 3.0% or more and the area ratio of the {100}<001> orientation region was low, and therefore the roundness evaluation was acceptable. In Example 7, the temperature of the second intermediate annealing [Step 5] was high, but within the specified range, so the area ratio of the {100}<001> orientation region was slightly higher than in Example 1, etc. In Example 11, the temperature of the solution heat treatment [Step 7] was high, but within the specified range, so the area ratio of the {100}<001> orientation region was slightly higher than in Example 1, etc. In Example 13, the time of the solution heat treatment [Step 7] was long, but within the specified range, so the area ratio of the {100}<001> orientation region was slightly higher than in Example 1, etc. In Examples 14 to 19, in which optional components were included in the alloy composition, and Examples 20 to 23, in which the alloy composition was different from that of Examples 1 to 13, by performing each step under appropriate conditions, the area ratio of the {111}<112> orientation region was able to be controlled to 3.0% or more and the area ratio of the {100}<001> orientation region was able to be controlled to a low value, and the evaluation of roundness was therefore successful.

[0069] In Comparative Examples 1 to 6, the area ratio of the {111}<112> orientation region was less than 3.0% and the evaluation of the circularity was impossible because the conditions of the first intermediate annealing [Step 4], the second intermediate annealing [Step 5], or the solution heat treatment [Step 7] were inappropriate. In Comparative Examples 7 to 12, the area ratio of the {111}<112> orientation region was less than 3.0% and the evaluation of the circularity was impossible because the alloy composition was inappropriate.

Claims

1. A copper alloy sheet having an alloy composition containing 1.00% by mass or more and 5.00% by mass or less of Ni, 0.20% by mass or more and 1.50% by mass or less of Si, and a total of 0% by mass or more and 1.00% by mass or less of at least one element selected from the group consisting of Sn, Zn, Mg, Fe, and Cr, with the balance being Cu and unavoidable impurities, and having an area ratio of a region of a crystal orientation within 20° from the {111}<112> orientation, obtained by measurement by the EBSD method with respect to the surface, of 3.0% or more.

2. The copper alloy sheet according to claim 1, wherein an area ratio of a region of a crystal orientation within 20° from the {100}<001> orientation, obtained by measurement by the EBSD method with respect to the surface of the copper alloy sheet, is 4.5% or less.

3. A copper alloy sheet for drawing, wherein the copper alloy sheet according to claim 1 or 2 is used for drawing.

4. A drawn product obtained by drawing the copper alloy sheet according to claim 1 or 2.

5. The drawn product according to claim 4, wherein when the maximum diameter at the edge of the drawn product is D (mm) and the minimum diameter is d (mm), the roundness I defined by the following formula (1) is 0.10 mm or less. Roundness I (mm) = {D (mm) - d (mm)} / 2 Formula (1)

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