Copper alloy sheet and drawn-out parts

Abstract

The present invention provides a copper alloy sheet material that exhibits excellent bendability and excellent deep drawing properties, and in particular, allows for the reduction of the lugs formed on the edges of deep-drawn products. [Solution] The copper alloy sheet material has an alloy composition in which Cr is contained in a range of 0.10 mass% to 1.00 mass%, with the remainder being Cu and unavoidable impurities, and in crystal orientation analysis by EBSD performed in the measurement area of ​​the rolled surface, {011} <211> Brass direction, {123} <634> The S direction and {112} <111> The total area of ​​the crystal grains oriented in the Copper direction is in the range of 25% to 38% of the area of ​​the measurement region, and {001} <100> The area of ​​crystal grains oriented in the Cube orientation accounts for 12% or more of the area of ​​the measurement region.

Description

[Technical Field]

[0001] This invention relates to copper alloy sheet materials and drawn-out products. [Background technology]

[0002] Copper alloy sheets are used, for example, in connectors, lead frames, relays, switches, sockets, shield cases, shield cans, camera modules, heat dissipation components for LCD and OLED displays, and batteries for electronic equipment or automotive applications, and are often subjected to press working such as bending, drawing, punching, and stretching.

[0003] As a copper alloy used in such press working, for example, Patent Document 1 describes a copper alloy containing, by mass%, Cr: 0.10~0.50%, Ti: 0.010~0.30%, Si: 0.01~0.10%, with a mass ratio of Cr to Ti: 1.0≦(Cr / Ti)≦30, and a mass ratio of Cr to Si: 3.0≦(Cr / Si)≦30, with the remainder being copper and unavoidable impurities, and when the crystal orientation of the copper alloy is measured by the FESEM-EBSP method, it is a Brass orientation {011}. <211> , S direction {123} <634> and Copper direction {112} <111> A copper alloy having a texture in which the total average area ratio is 40% to 70% is disclosed. Patent Document 1 discloses the crystal orientation of a Cu-Cr-Ti-Si alloy as Brass orientation {011}. <211> , S direction {123} <634> and Copper direction {112} <111> It is claimed that when the total average area ratio is controlled to 40% to 70%, a copper alloy with excellent strength and conductivity, as well as excellent bendability, can be obtained.

[0004] Furthermore, Patent Document 2 describes a material containing 0.1 to 0.6 mass% Cr, 0.01 to 0.30 mass% of one or two of Zr and Ti in total, with the remainder being copper and unavoidable impurities, and in crystal orientation analysis in EBSD measurement, the Cube orientation {001} <100> Area ratio of 10% or less, Brass orientation {110} <112> Area ratio of 40% or less, Copper orientation {112} <111> The area ratio is 20% or more, and there are 100,000 second-phase particles / mm² with a size of 0.1 μm or larger. 2 The following copper alloy plates are disclosed. Patent Document 2 discloses a Cu-Cr-(Zr,Ti) alloy with a Cube orientation {001} <100> , Brass orientation {110} <112> and Copper direction {112} <111> By controlling the area ratio and the density of the second phase particles, it is possible to obtain a copper alloy sheet that maintains conductivity and strength while exhibiting excellent bendability, stress relaxation rate, and Young's modulus. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2013-173988 [Patent Document 2] Japanese Patent Publication No. 2019-157256 [Overview of the project] [Problems that the invention aims to solve]

[0006] In recent years, with the increasing performance, higher current, and miniaturization of electronic devices and automotive components, there has been a growing demand for high mechanical properties and electrical conductivity (or thermal conductivity) in the press-formed products that make up these devices. In particular, for deep-drawn parts used in electronic devices and automotive components, such as connectors, lead frames, relays, switches, sockets, shield cases, shield cans, camera module cases, vibration device cases, heat dissipation components for liquid crystal and organic EL displays, batteries, probe pins, and gas shielding valves, there is a need for copper alloy sheets made from materials that offer both higher mechanical properties and electrical conductivity (or thermal conductivity) than conventional copper alloys such as brass and nickel silver. Cu-Cr alloys are known to possess such high strength and electrical conductivity (thermal conductivity), but Cu-Cr alloys have poor ductility and are not suitable for complex processing. Therefore, there is a demand for copper alloy sheets made from Cu-Cr alloys that have excellent bendability and excellent deep-drawing properties.

[0007] Here, "deep drawing" refers to a type of metal sheet forming method, typically involving pressing a punch into a thin sheet of metal to form various bottomed containers of different shapes, such as cylinders, rectangular tubes, and cones. "Deep-drawn products" refer to products formed by deep drawing, characterized by the absence of seams in the formed product. It should be noted that "deep-drawn products" also include products formed by combining deep drawing with other processing methods, such as bending, crushing, and twisting.

[0008] Increasing the depth of this deep drawing process often makes the material more prone to fracture, making processing difficult. Even if processing is possible without fracture, large ridges (ears) tend to form on the edges of the resulting deep-drawn product. In particular, deep drawing processes with a large depth relative to the punch diameter require multiple stages of deep drawing, which makes the ears especially prone to becoming large. When large ears are formed, not only does it impair the shape of the deep-drawn product, but adjacent ears tend to overlap during the deep-drawing process, or cracks tend to form between adjacent ears. Furthermore, when large ears are formed, an additional process is required to remove them from the deep-drawn product. Therefore, there is a need for copper alloy sheet materials that can reduce the amount of ears formed on the edges of deep-drawn products.

[0009] In this regard, the Cu-Cr-Ti-Si alloy described in Patent Document 1 has high anisotropy because a large proportion of it is concentrated in the Brass, S, and Copper orientations, which are the processing textures. However, Patent Document 1 does not consider deep drawing, which is affected by anisotropy in all directions, and furthermore, it does not disclose how to achieve both small lugs formed on the edges of the deep-drawn product and excellent bendability, nor does it show evaluation results of these properties. In this regard, the Cu-Cr-Ti-Si alloy of Patent Document 1 has high anisotropy because a large proportion of it is concentrated in the Brass, S, and Copper orientations, so when this copper alloy is used in deep drawing, large lugs are formed on the edges of the deep-drawn product.

[0010] Furthermore, the Cu-Cr-(Zr,Ti) alloy described in Patent Document 2 has high anisotropy, particularly with a large accumulation rate of over 20% in the Copper orientation, and the accumulation rate in the Brass orientation can reach 40%. However, Patent Document 2 does not consider deep drawing processes, where anisotropy in all directions is influential, nor does it disclose how to achieve both minimizing the lugs formed on the edges of the deep-drawn product and excellent bendability, nor does it show any evaluation results for these properties. In this regard, the Cu-Cr-(Zr,Ti) alloy of Patent Document 2 has a large accumulation rate in the Copper orientation and exhibits high anisotropy, so even if this copper alloy is used in deep drawing, lugs are likely to form on the edges of the resulting deep-drawn product. Also, the Cu-Cr-(Zr,Ti) alloy of Patent Document 2 has a small accumulation rate of less than 10% in the Cube orientation, so when bending is performed under harsh conditions, wrinkles are easily formed in the processed area, and cracks are likely to occur, resulting in low bendability.

[0011] Furthermore, the Cu-Cr-Ti-Si alloy described in Patent Document 1 and the Cu-Cr-(Zr,Ti) alloy described in Patent Document 2, in terms of their manufacturing methods, involve hot rolling followed immediately by cold rolling, and do not involve an intermediate annealing process to precipitate additive components such as Cr after the hot rolling process.

[0012] Therefore, the present invention has been made in view of the above problems, and aims to provide a copper alloy sheet material that has excellent bendability and excellent deep drawing properties, and in particular, that can reduce the amount of lugs formed on the edges of deep-drawn products. [Means for solving the problem]

[0013] The inventors have found that in a copper alloy sheet having an alloy composition containing Cr in the range of 0.10% to 1.00% by mass and the balance consisting of Cu and inevitable impurities, in the EBSD method described later, the total area of crystal grains oriented in the Brass orientation, S orientation, and Copper orientation respectively, occupies a ratio (hereinafter, may be simply referred to as "the ratio of the total area of crystal grains oriented in the Brass orientation, S orientation, and Copper orientation") of 25% or more and 38% or less of the area of the measurement region, and the area of crystal grains oriented in the {001}<100> Cube orientation occupies a ratio (hereinafter, may be simply referred to as "the ratio of the area of crystal grains oriented in the Cube orientation") of 12% or more of the area of the measurement region. Thus, the copper alloy sheet has excellent bending workability and improves the drawing workability, particularly can reduce the ears formed at the edges of drawn products, and the present invention has been completed.

[0014] That is, the characteristic configuration of the present invention is as follows. (1) A copper alloy sheet having an alloy composition containing Cr in the range of 0.10% to 1.00% by mass and the balance consisting of Cu and inevitable impurities, wherein in the crystal orientation analysis by the EBSD method performed in the measurement region of the rolling surface of the copper alloy sheet, the total area of crystal grains oriented in the {011}<211> Brass orientation, {123}<634> S orientation, and {112}<111> Copper orientation respectively, occupies a ratio of 25% or more and 38% or less of the area of the measurement region, and the area of crystal grains oriented in the {001}<100> Cube orientation occupies a ratio of 12% or more of the area of the measurement region.

[0015] (2) The copper alloy sheet according to (1) above, wherein the average crystal grain size of crystal grains on the rolling surface is 15 μm or less.

[0016] (3) The copper alloy sheet according to (1) or (2) above, wherein the alloy composition further contains at least one optional additive component selected from the group consisting of Mg, Sn, Zn, Fe, Si, and Zr, in a total range of 0.05% to 0.50% by mass.

[0017] (4) The copper alloy sheet according to any one of (1) to (3) above, which is used as a blank for drawing.

[0018] (5) A drawn product obtained by drawing the copper alloy sheet according to any one of (1) to (3) above.

Advantages of the Invention

[0019] According to the present invention, it is possible to provide a copper alloy sheet that has excellent bending workability and improved drawing workability, and in particular, can reduce the ears formed at the edges of the drawn product.

Brief Description of the Drawings

[0020] [Figure 1] FIG. 1 is a diagram for explaining a rough position when measuring the size of the ears (undulations) formed at the edge of a drawn product of a copper alloy sheet. It is a plan view of the copper alloy sheet which is the original sheet before drawing, when eight line segments extending in the radial direction from the position that becomes the center of the bottom surface to the position of the circular contour line in the drawn product are drawn at positions rotated clockwise by 45° with the rolling direction being 0°. [Figure 2] FIG. 2 is a perspective view of a drawn product produced using the copper alloy sheet shown in FIG. 1, showing the height from the bottom surface position of the drawn product to the position of the ears existing on the upper edge.

Embodiments for Carrying Out the Invention

[0021] Next, embodiments of the present invention will be described. The following description shows examples of embodiments in the present invention and does not limit the scope of the claims.

[0022] The copper alloy sheet material according to the present invention has an alloy composition in which Cr is contained in a range of 0.10 mass% to 1.00 mass%, with the remainder being Cu and unavoidable impurities, and in crystal orientation analysis by EBSD performed on the measurement area of ​​the rolled surface of the copper alloy sheet material, {011} <211> Brass direction, {123} <634> The S direction and {112} <111> The proportion of the total area of ​​crystal grains oriented in the Copper direction is in the range of 25% to 38%, and {001} <100> The proportion of the area of ​​crystal grains oriented in the Cube orientation is 12% or more.

[0023] The copper alloy sheet material of the present invention contains at least an appropriate amount of Cr and is manufactured under appropriate manufacturing conditions to suppress the growth of coarse crystal grains. As a result, the proportion of the total area of ​​crystal grains oriented in the Brass, S, and Copper orientations is relatively small, in the range of 25% to 38%, while the proportion of the area of ​​crystal grains oriented in the Cube orientation is relatively large, at 12% or more. This reduces anisotropy, thereby reducing the rim formed on the edge of the drawn product, i.e., the waviness of the edge of the drawn product. Therefore, by adopting the above configuration, the present invention can provide a copper alloy sheet material that has excellent bendability and excellent drawing processability, even for Cu-Cr alloys that have poor elongation and are unsuitable for complex processing, and in particular, can reduce the rim formed on the edge of the drawn product, as well as a drawn product using the same.

[0024] In this regard, the bendability and deep drawing properties of copper alloy sheets vary greatly depending on the anisotropy of the copper alloy sheet, i.e., the crystal orientation. Of these, it is widely known that bendability is improved by accumulation in the Cube orientation. In this regard, conventional Cu-Cr alloys hardly oriented in the Cube orientation, and the proportion of the area of ​​crystal grains oriented in the Cube orientation is often less than 1%, resulting in poor bendability. Furthermore, regarding deep drawing properties, the less anisotropic the material, the less likely it is that ears will develop on the edges of the deep-drawn product. However, conventional Cu-Cr alloys have a strong orientation towards the Brass, S, and Copper orientations, which are processing textures, and therefore also have poor deep drawing properties. In this respect, the copper alloy sheet of the present invention reduces the orientation of crystal grains towards the Brass, S, and Copper orientations, while increasing the orientation of crystal grains towards the Cube orientation. This makes it possible to have crystal grains oriented in various crystal orientations in a state of nearly equal proportions, and as a result, it is possible to achieve both excellent bendability and excellent deep drawing properties.

[0025] [1] Alloy composition of copper alloy sheet material The copper alloy sheet material of the present invention has an alloy composition containing Cr in an essential component range of 0.10% by mass or more and 1.00% by mass or less. Because the copper alloy sheet material of the present invention has an alloy composition of a Cu-Cr alloy containing at least an appropriate amount of Cr, it has excellent bendability and excellent deep drawing properties, as well as high tensile strength and high electrical conductivity. The following explains the reasons for limiting the alloy composition of the copper alloy sheet material.

[0026] (Cr: 0.10 mass% or more and 1.00 mass% or less) Cr (chromium) is an important component that enhances the material strength of copper alloy sheets and is contained in a range of 0.10% by mass or more and 1.00% by mass or less. If the Cr content is less than 0.10% by mass, the desired material strength cannot be obtained. Furthermore, if the Cr content is greater than 1.00% by mass, a coarse second phase is more likely to form, and this second phase is likely to become the starting point for cracks during deep drawing. Therefore, from the viewpoint of enhancing the material strength of copper alloy sheets and making it less likely for cracks to occur in deep-drawn products, the Cr content is in the range of 0.10% by mass or more and 1.00% by mass or less, preferably in the range of 0.20% by mass or more and 0.80% by mass or less, and more preferably in the range of 0.30% by mass or more and 0.70% by mass or less.

[0027] <Optional addition ingredients> Furthermore, the alloy composition of the copper alloy sheet material of the present invention may further contain, as an optional additive, at least one component selected from the group consisting of Mg, Sn, Zn, Fe, Si, and Zr, in a total amount of 0.05% by mass or more and 1.00% by mass or less.

[0028] (Mg: 0.10 mass% or more and 0.30 mass% or less) Magnesium (Mg) is a component that improves stress relaxation resistance. To achieve this effect, it is preferable to have a Mg content of 0.10% by mass or more. On the other hand, if the Mg content exceeds 0.30% by mass, the conductivity tends to decrease. Therefore, it is preferable that the Mg content be in the range of 0.10% by mass or more and 0.30% by mass or less.

[0029] (Sn: 0.10 mass% or more and 0.30 mass% or less) Sn (tin) is a component that improves stress relaxation resistance. To achieve this effect, the Sn content is preferably 0.10% by mass or more. On the other hand, if the Sn content exceeds 0.30% by mass, the conductivity tends to decrease. Therefore, the Sn content is preferably in the range of 0.10% by mass or more and 0.30% by mass or less.

[0030] (Zn: 0.10 mass% or more and 0.50 mass% or less) Zinc (Zn) is a component that improves the adhesion and migration characteristics of Sn plating. To achieve this effect, it is preferable to have a Zn content of 0.10% by mass or more. On the other hand, if the Zn content exceeds 0.50% by mass, the conductivity tends to decrease. Therefore, it is preferable that the Zn content be in the range of 0.10% by mass or more and 0.50% by mass or less.

[0031] (Fe: 0.05 mass% or more and 0.30 mass% or less) Fe (iron) is a component that, in the hot rolling process described later [Step 3], has the effect of suppressing grain coarsening after dynamic recrystallization and preventing surface roughness of the drawn product. To achieve this effect, it is preferable that the Fe content be 0.05% by mass or more. Furthermore, if the Fe content exceeds 0.30% by mass, coarse crystals containing Fe tend to form during casting, making it easier for crack initiation points to be formed. For this reason, it is preferable that the Fe content be in the range of 0.05% by mass or more and 0.30% by mass or less.

[0032] (Si: 0.05 mass% or more and 0.30 mass% or less) Silicon (Si) is a component that improves the tensile strength of copper alloy sheets. To achieve this effect, it is preferable to have a Si content of 0.05% by mass or more. Furthermore, if the Si content exceeds 0.30% by mass, coarse precipitates containing Si tend to form during casting, making it easier for crack initiation points to occur. For this reason, it is preferable that the Si content be in the range of 0.05% by mass or more and 0.30% by mass or less.

[0033] (Zr: 0.05 mass% or more and 0.30 mass% or less) Zr (zirconium) is a component that, in the hot rolling process described later [Step 3], has the effect of suppressing grain coarsening after dynamic recrystallization and preventing surface roughness of drawn products. To achieve this effect, it is preferable that the Zr content be 0.05% by mass or more. Furthermore, if the Zr content exceeds 0.30% by mass, coarse crystals containing Zr are more likely to form during casting, which makes it easier for crack initiation points to be formed. For this reason, it is preferable that the Zr content be in the range of 0.05% by mass or more and 0.30% by mass or less.

[0034] (Total content of optional additives: 0.05% by mass or more, 1.00% by mass or less) These optional additives are preferably present in a total amount of 0.05% by mass or more, and more preferably 0.10% by mass or more, in order to obtain the effects of the optional additives described above. On the other hand, since the conductivity decreases if these optional additives are present in large quantities, the total content of the optional additives is preferably 1.00% by mass or less, and more preferably 0.50% by mass or less.

[0035] (Remaining components: Cu and unavoidable impurities) The Cu alloy that constitutes the copper alloy sheet material has an alloy composition consisting of the above-mentioned components, with the remainder being Cu (copper) and unavoidable impurities. Here, "unavoidable impurities" generally refer to substances present in the raw materials or inevitably introduced during the manufacturing process of metal products. While these are inherently unwanted, their presence is minimal and does not affect the properties of the metal product, making them permissible. Examples of unavoidable impurities include nonmetallic elements such as sulfur (S), carbon (C), and oxygen (O), and metallic elements such as antimony (Sb). The upper limit for the content of these components can be, for example, 0.05 mass% for each component and 0.20 mass% for the total amount of these components.

[0036] [2] Percentage of total area of ​​crystal grains oriented in Brass, S, and Copper orientations In the crystal orientation analysis performed by EBSD on the measurement area of ​​the rolled surface of the copper alloy sheet material of the present invention, {011} <211> Brass direction, {123} <634> The S direction and {112} <111> The total area obtained by adding the areas of the crystal grains oriented in the Copper direction is such that the proportion of the measurement area is between 25% and 38%. Crystal grains oriented in the Brass, S, and Copper directions form ears at the edges of the drawn product at angles of approximately 45°, 135°, 225°, and 315° with respect to the rolling direction, and these ears are called 45° ears. By making the proportion of the total area of ​​crystal grains oriented in the Brass, S, and Copper directions 38% or less, the crystal orientation of the crystal phase becomes closer to random, and the anisotropy of the metal structure is reduced, resulting in smaller or no 45° ears being formed during the drawing process. As a result, a copper alloy sheet material can be obtained that can be drawn uniformly without fracture. On the other hand, if the total area ratio of crystal grains oriented in the Brass, S, and Copper directions exceeds 38%, 45° lugs develop significantly, greatly reducing the formability for deep drawing. Therefore, from the viewpoint of obtaining a copper alloy sheet material with excellent formability for deep drawing, the total area ratio of crystal grains oriented in the Brass, S, and Copper directions is preferably in the range of 25% to 38%, and more preferably in the range of 25% to 32%.

[0037] Here, the ratio of the total area of ​​crystal grains oriented in the Brass, S, and Copper orientations can be obtained from crystal orientation analysis data calculated using analysis software (TSL Corporation, OIM Analysis) from crystal orientation data continuously measured using an EBSD detector attached to a high-resolution scanning electron microscope (JEOL Ltd., JSM-7001FA). "EBSD" stands for Electron Backscatter Diffraction, a crystal orientation analysis technique that utilizes backscattered electron Kikuchi line diffraction generated when an electron beam is irradiated onto a copper plate sample in a scanning electron microscope (SEM). "OIM Analysis" is software for analyzing data measured by EBSD. Measurements can be performed on the rolled surface of the copper alloy plate. The measurement area on the rolled surface is approximately 1000 μm × 1000 μm, and measurements can be performed with a scan step size of 0.2 μm. From the crystal orientation analysis data of such a measurement area, {011} <211> Brass direction, {123} <634> The S direction and {112} <111> The atomic planes of crystal grains having a deviation angle of 10° or less from each of the copper orientations are defined as the atomic planes of crystal grains oriented in the brass, S, and copper orientations, respectively. By determining the areas of these atomic planes and dividing them by the area of ​​the measurement region, the respective ratios of the areas of crystal grains oriented in the brass, S, and copper orientations, and the ratio of the total area of ​​crystal grains oriented in the brass, S, and copper orientations can be determined. Here, in order to ensure quantitative accuracy through measurement over a wide area, the crystal orientation may be measured on the surface of the copper alloy plate, and in this case, it is preferable to use the average value obtained by measuring in three or more fields of view.

[0038] Here, it is preferable that the area of ​​crystal grains oriented in the Brass direction accounts for 6% or less of the area of ​​the measurement region. Furthermore, it is preferable that the area of ​​crystal grains oriented in the S direction accounts for 28% or less of the area of ​​the measurement region. Furthermore, it is preferable that the area of ​​crystal grains oriented in the Copper direction accounts for 8% or less of the area of ​​the measurement region.

[0039] [3] Percentage of the area of ​​crystal grains oriented in the cubic direction In the crystal orientation analysis performed by EBSD on the measurement area of ​​the rolled surface of the copper alloy sheet material of the present invention, {001} <100> The area of ​​crystal grains oriented in the Cube orientation accounts for 12% or more of the area of ​​the measurement region. Crystal grains oriented in the Cube orientation form ears at the edges of the drawn product in directions that are approximately 0°, 90°, 180°, and 270° with respect to the rolling direction. These ears are called "0° ears," and ears also form in directions that are approximately 45°, 135°, 225°, and 315° with respect to the rolling direction. These ears are called "45° ears." By increasing the area of ​​crystal grains oriented in the Cube orientation to 12% or more, the bendability of the copper alloy sheet can be improved, and the area where 0° ears are formed can be expanded, making the 45° ears relatively smaller. On the other hand, if the area of ​​crystal grains oriented in the Cube orientation is less than 12%, it becomes difficult to improve the bendability, resulting in cracks and deep wrinkles on the surface of the copper alloy sheet after bending. Therefore, the proportion of the area of ​​crystal grains oriented in the Cube orientation is 12% or more, preferably 14% or more, and more preferably 15% or more, from the viewpoint of obtaining a copper alloy sheet material with excellent bendability. The upper limit of the proportion of the area of ​​crystal grains oriented in the Cube orientation is not particularly limited, but from the viewpoint of preventing the process of oriented the crystal grains in the Cube orientation from becoming redundant and increasing the productivity of the copper alloy sheet material, it may be, for example, 25% or 20%.

[0040] Here, the proportion of the area of ​​crystal grains oriented in the Cube orientation can be obtained from crystal orientation analysis data calculated using analysis software (TSL Corporation, OIM Analysis) from crystal orientation data continuously measured using an EBSD detector attached to a high-resolution scanning electron microscope (JEOL Ltd., JSM-7001FA). At this time, from the crystal orientation analysis data, {001} <100> By determining the area of ​​the atomic planes of crystal grains that have a deviation angle of 10° or less from the Cube orientation, and considering these as the atomic planes of crystal grains oriented in the Cube orientation, and then dividing these areas by the area of ​​the measurement region (measurement area), the proportion of the area of ​​crystal grains oriented in the Cube orientation can be determined.

[0041] [4] Average grain size of crystal grains on the rolled surface In the present invention, the copper alloy sheet material preferably has an average grain size of 15 μm or less on the rolled surface. When deep drawing is performed on the copper alloy sheet material, a larger average grain size improves the deep drawing processability. However, if the average grain size of the grains on the rolled surface exceeds 15 μm, the likelihood of cracking or excessive wrinkling at the bent portion increases when the copper alloy sheet material is bent. Therefore, from the viewpoint of further improving the bendability of the copper alloy sheet material, the average grain size of the grains contained on the rolled surface is preferably 15 μm or less, and more preferably 13 μm or less.

[0042] The average grain size of a copper alloy sheet can be determined by the cutting method specified in JIS H0501. More specifically, the rolled surface of a copper alloy sheet is polished to a mirror finish by wet polishing and buffing, and the polished surface is then etched with a weak acid solution for several seconds. When the surface is observed at 500x magnification using an optical microscope (OM), ten line segments corresponding to a length of 100 μm (line segments with a length of 50 mm in the optical microscope image) are drawn parallel to each other along the rolling direction. The total number of points where each line segment intersects with the grain boundary is counted, and the average length of each section of the line segment demarcated by the grain boundary is calculated using the following formula (I). This allows the average grain size (μm), which is the average length of each section of the line segment, to be determined. Average length of each section of the line segment [μm] = 100 [μm] × 10 / (total number of intersections between the line segment and grain boundaries) ... (I)

[0043] [5] Method for manufacturing copper alloy sheet The copper alloy sheet material described above can be realized by controlling the combination of alloy composition and manufacturing process, and the manufacturing process is not particularly limited. Among these, the following method can be cited as an example of a manufacturing process that can obtain both excellent bendability and excellent deep drawing properties.

[0044] An example of a method for manufacturing a copper alloy sheet material of the present invention involves sequentially performing at least the following steps on a copper alloy material having an alloy composition equivalent to that of the copper alloy sheet material described above: a melting and casting step [step 1], a reheating step [step 2], a hot rolling step [step 3], a first intermediate annealing step [step 4], a first cold rolling step [step 5], a second intermediate annealing step [step 6], a second cold rolling step [step 7], an aging heat treatment step [step 8], a third cold rolling step [step 9], and a low-temperature annealing step [step 10]. In this manufacturing method, in particular, by performing intermediate annealing, which is not generally performed in Cu-Cr alloys, twice in the first intermediate annealing step [step 4] and the second intermediate annealing step [step 6], the crystal orientation is appropriately controlled, so that the total proportion of crystal grains oriented in the Brass, S, and Copper orientations and the proportion of crystal grains oriented in the Cube orientation can be controlled within the above range.

[0045] (i) Melting and casting process [Process 1] The melting and casting process [Step 1] involves melting a copper alloy material having an alloy composition equivalent to the alloy composition described above, and casting it to produce an ingot of a predetermined shape (for example, 30 mm thick, 100 mm wide, and 150 mm long). In the melting and casting process [Step 1], it is preferable to melt and cast the copper alloy material in air, an inert gas atmosphere, or a vacuum using a high-frequency melting furnace.

[0046] Furthermore, while the alloy composition of the copper alloy material may not perfectly match that of the copper alloy sheet produced due to the adhering or volatilization of some added components during each manufacturing process, it has substantially the same alloy composition as the copper alloy sheet.

[0047] (ii) Reheating process [Process 2] The reheating process [Process 2] is a process in which heat treatment is performed on the ingot after the casting process [Process 1]. The conditions for the heat treatment in the reheating process [Process 2] are preferably such that the target temperature (heat treatment temperature) is in the range of 900°C to 1050°C, and the holding time at the target temperature (heat treatment time) is in the range of 1 hour to 10 hours. If the target temperature is less than 900°C, dynamic recrystallization will not occur sufficiently in the hot rolling process [Process 3] described later, making it easy for a non-uniform structure to form. On the other hand, if the target temperature exceeds 1050°C, the grain boundaries become weaker, making it easy for cracks to occur in the hot-rolled material after the hot rolling process [Process 3].

[0048] (iii) Hot rolling process [Process 3] The hot rolling process [Step 3] is a process in which the ingot that has undergone the reheating process [Step 2] is hot-rolled to a predetermined thickness to produce a hot-rolled material. The conditions for the hot rolling process [Step 3] can be set to conditions that cause dynamic recrystallization, for example, the rolling temperature can be set to 950°C or higher, and the total reduction rate can be set to 90% or higher. On the other hand, if dynamic recrystallization does not occur sufficiently in the hot rolling process [Step 3], the resulting copper alloy sheet material tends to have a non-uniform structure.

[0049] In this specification, the "processing rate" (reduction rate) is the value obtained by subtracting the cross-sectional area after rolling from the cross-sectional area before rolling, dividing the result by the cross-sectional area before rolling, multiplying by 100, and expressing it as a percentage, and is expressed by the following formula. [Processing rate] = {([Cross-sectional area before rolling] - [Cross-sectional area after rolling]) / [Cross-sectional area before rolling]} × 100 (%)

[0050] After the hot working process [Step 3], the hot-rolled material may be subjected to surface milling. Surface milling can remove surface oxide films and defects that occurred during the hot working process [Step 3]. The conditions for surface milling can be any conditions that are normally used and are not particularly limited. The amount of material removed from the surface of the hot-rolled material by surface milling can be appropriately adjusted based on the oxidation state of the surface, for example, to about 1 mm to 5 mm from the surface of the hot-rolled material.

[0051] (iv) First intermediate annealing process [Process 4] The first intermediate annealing process [process 4] is a process in which the hot-rolled material, after the hot working process [process 3], is subjected to heat treatment according to the alloy composition.

[0052] In the first intermediate annealing step [step 4], the annealing conditions are preferably such that the target temperature is in the range of 450°C to 650°C and the holding time at the target temperature is in the range of 30 minutes to 2 hours. By performing heat treatment in the range of 450°C to 600°C, chromium precipitates precipitate, which changes the solid solution state. The precipitated chromium precipitates also provide a pinning effect on the growth of crystal grains, making it difficult for coarse crystal grains to grow. As a result, crack formation originating from coarse crystal grains is less likely to occur during deep drawing. Furthermore, accumulation in the Cube orientation, which was previously almost nonexistent, can be made easier, and anisotropy is reduced as various crystal orientations develop, making it possible to reduce the size of the rim formed on the edge of the deep-drawn product.

[0053] Here, if the temperature reached in the first intermediate annealing step [step 4] is lower than 450°C, sufficient sized Cr-based precipitates will not precipitate, making it difficult for the pinning effect on grain growth to occur, thus making it easier for coarse grains to grow. Also, if the temperature reached in the first intermediate annealing step [step 4] is higher than 650°C, the Cr-based precipitates will redissolve, making it easier for coarse grains to grow. If the temperature reached is lower than 450°C or higher than 650°C, a highly anisotropic metal structure will be formed, resulting in poor deep drawing properties for the resulting copper alloy sheet. In particular, from the viewpoint of improving the deep drawing properties of the resulting copper alloy sheet, it is more preferable that the temperature reached in the first intermediate annealing step [step 4] is in the range of 450°C to 600°C.

[0054] Furthermore, if the heat treatment time (holding time at the target temperature) in the first intermediate annealing process [Step 4] is less than 30 minutes, the growth of crystal grains will be insufficient. On the other hand, even if the holding time at the target temperature is extended beyond 2 hours, the change in crystal grains becomes small, so longer heat treatment is undesirable from a productivity standpoint.

[0055] (v) First cold rolling process [Process 5] The first cold rolling process [process 5] is a process in which the hot-rolled material, after undergoing the first intermediate annealing process [process 4], is cold-rolled.

[0056] In the first cold rolling process [process 5], the total processing rate is preferably in the range of 75% to 90%. Here, if the total processing rate is less than 75% or greater than 90%, the total proportion of crystal grains oriented in the Brass, S, and Copper orientations increases, which increases the anisotropy of the metal structure, resulting in larger rims formed on the edges of the drawn product.

[0057] (vi) Second intermediate annealing process [Process 6] The second intermediate annealing process [process 6] is a process in which the cold-rolled material after the first cold-rolling process [process 5] is subjected to heat treatment according to the alloy composition.

[0058] In the second intermediate annealing step [step 6], the annealing conditions are preferably such that the target temperature is in the range of 450°C to 600°C and the holding time at the target temperature is in the range of 30 minutes to 2 hours. By performing heat treatment in the range of 450°C to 600°C, Cr-based precipitates further precipitate, changing the solid solution state, and thus reducing anisotropy in the subsequent second cold rolling step [step 7]. In addition, by performing heat treatment in the range of 450°C to 600°C, static recrystallization occurs, changing the metal structure from a highly anisotropic processed texture to a less anisotropic recrystallized texture, and because the crystal orientation is nearly random, the proportion of the total area of ​​crystal grains oriented in the Brass, S, and Copper orientations can be significantly reduced compared to conventional processes. At the same time, since the crystal grains with the Cube orientation formed in the first intermediate annealing step [step 4] grow, the proportion of the area of ​​crystal grains oriented in the Cube orientation can be increased.

[0059] Here, if the temperature reached in the second intermediate annealing step [step 6] is lower than 450°C, precipitation of Cr-based precipitates and changes in the metal structure do not occur, and therefore the proportion of the total area of ​​crystal grains oriented in the Brass, S, and Copper directions does not decrease. On the other hand, if the temperature reached in the second intermediate annealing step [step 6] is higher than 600°C, the proportion of the total area of ​​crystal grains oriented in the Brass, S, and Copper directions actually increases, and the proportion of the area of ​​crystal grains oriented in the Cube direction actually decreases.

[0060] Furthermore, if the heat treatment time (holding time at the target temperature) in the second intermediate annealing process [step 6] is less than 30 minutes, the precipitation of Cr-based precipitates and the change in the metal structure will be insufficient. On the other hand, even if the holding time at the target temperature is extended beyond 2 hours, the change in crystal grains becomes small, so longer heat treatment is undesirable from a productivity standpoint.

[0061] (vii) Second cold rolling process [Process 7] The second cold rolling process [process 7] is a process in which the cold-rolled material, after undergoing the second intermediate annealing process [process 6], is cold-rolled.

[0062] The total processing rate in the second cold rolling process [step 7] is preferably in the range of 15% to 35%, and more preferably in the range of 15% to 30%. This allows the grains oriented in the Brass, S, and Copper directions, which were greatly reduced in the second intermediate annealing process [step 6], to be appropriately restored in the second cold rolling process [step 7], thereby making the grain orientation in the metal structure closer to random. Here, if the total processing rate in the second cold rolling process [step 7] is less than 15%, the grain orientation in the metal structure hardly changes after the second intermediate annealing process [step 6]. Also, if the total processing rate in the second cold rolling process [step 7] is greater than 30%, and especially greater than 35%, the proportion of the area of ​​at least one of the grains oriented in the Brass, S, and Copper directions, and especially the proportion of the area of ​​grains oriented in the S direction, increases.

[0063] (viii) Aging heat treatment process [Process 8] The aging heat treatment process [Step 8] is a process in which the cold-rolled material after the second cold-rolling process [Step 7] is heat-treated to strengthen it by precipitation. Here, the conditions for the heat treatment in the aging heat treatment process [Step 8] are that the target temperature is in the range of 400°C to 500°C, and the holding time at the target temperature is in the range of 1 hour to 4 hours. If the target temperature is less than 400°C or the holding time is less than 1 hour, it becomes difficult to obtain precipitation strengthening, and the tensile strength of the copper alloy sheet material tends to decrease. On the other hand, if the target temperature exceeds 500°C or the holding time exceeds 4 hours, the precipitates become coarser, and the tensile strength of the copper alloy sheet material tends to decrease. In particular, from the viewpoint of increasing the tensile strength of the copper alloy sheet material by precipitation strengthening, it is preferable that the target temperature in the aging heat treatment process [Step 8] is 450°C or higher.

[0064] (ix) Third cold rolling process [Process 9] The third cold rolling process [process 9] is a process in which the cold-rolled material after the aging heat treatment process [process 8] is subjected to further cold rolling. Here, the total processing rate in the third cold rolling process [process 9] can be set according to the desired material strength of the copper alloy sheet, and is preferably in the range of 5% to 30%, and more preferably in the range of 5% to 25%. Here, if the total processing rate is less than 5%, the amount of work hardening will be small, making it difficult to obtain the effect of increasing the tensile strength of the copper alloy sheet. Also, if the total processing rate is greater than 25%, and especially greater than 30%, the elongation of the copper alloy sheet decreases, which reduces at least one of the drawability and bendability.

[0065] (x) Low-temperature annealing process [Process 10] The low-temperature annealing process [step 10] is an annealing process in which heat treatment is applied to the cold-rolled material after the third cold-rolling process [step 9]. The heat treatment conditions in this low-temperature annealing process [step 10] are preferably such that the target temperature is in the range of 200°C to 400°C and the holding time at the target temperature is in the range of 10 seconds to 30 minutes. If the target temperature is less than 200°C or the holding time is less than 10 seconds, the strain remaining in the cold-rolled material after annealing will be excessive, reducing the drawability of the copper alloy sheet material. On the other hand, if the target temperature exceeds 400°C or the holding time at the target temperature exceeds 30 minutes, the work hardening due to cold rolling will disappear.

[0066] [6] Applications of copper alloy sheets The copper alloy sheet material of the present invention is preferably used as a base material for deep drawing. That is, the copper alloy sheet material of the present invention is particularly suitable for deep drawing to obtain deep-drawn products, and is suitable for forming deep-drawn parts used in electronic devices and automotive equipment, for example. More specifically, it is suitable for use in connectors, lead frames, relays, switches, sockets, shield cases, shield cans, camera module cases, vibration device cases, heat dissipation components for liquid crystal and organic EL displays, batteries, probe pins, gas shielding valves, etc., for electronic devices and automotive equipment, where high performance, high current, and miniaturization are particularly required. Among these, it is especially preferable to use it in connector hold-downs and shells, camera module cases, battery cases, shield cases, and contact probes. These parts are often manufactured by combining deep drawing and bending, but by using the copper alloy sheet material of the present invention, it is possible to achieve both excellent deep drawing and bending properties, making it suitable for use in these applications. Furthermore, because the copper alloy sheet material of the present invention has a Cu-Cr alloy composition, it exhibits higher electrical conductivity (thermal conductivity) than brass or nickel silver, which have been conventionally used in deep drawing processes. Therefore, it can be suitably used in parts that require high heat dissipation.

[0067] Although embodiments of the present invention have been described above, the present invention is not limited to the embodiments described above, and includes all aspects included in the concept and claims of the present invention, and can be modified in various ways within the scope of the present invention. [Examples]

[0068] Next, in order to further clarify the effects of the present invention, examples and comparative examples of the present invention will be described, but the present invention is not limited to these examples.

[0069] (Examples 1-16 of the present invention and Comparative Examples 1-9) Various copper alloy materials having the alloy compositions shown in Table 1 were melted and cast in a melting and casting process [Step 1], which involved cooling them in an atmospheric environment to obtain ingots. These ingots were then subjected to a reheating process [Step 2], in which they were heat-treated at a target temperature of 950°C and held at that temperature for 5 hours (heat-treatment time). Subsequently, a hot rolling process [Step 3] was performed, in which the ingots were rolled so that the longitudinal direction was the rolling direction, resulting in a total processing rate of 90% or more, to obtain hot-rolled material. The rolled material after the hot rolling process [Step 3] was then subjected to a first intermediate annealing process [Step 4], in which it was heat-treated at the target temperature and holding time described in Table 2, and then cooled to room temperature by water cooling.

[0070] After the hot-rolled material has cooled, surface milling is performed to remove approximately 1 mm to 5 mm from both the front and back surfaces to remove the surface oxide film. Then, a first cold rolling process [Step 5] is performed, in which the material is rolled at the processing rate shown in Table 2 so that the longitudinal direction of the hot-rolled material is the rolling direction. Next, a second intermediate annealing process [Step 6] is performed on the cold-rolled material after the first cold rolling process [Step 5], in which it is heat-treated at the temperature and holding time shown in Table 2. Then, a second cold rolling process [Step 7] is performed, in which the material is rolled at the processing rate shown in Table 2 so that the longitudinal direction of the hot-rolled material is the rolling direction.

[0071] The cold-rolled material after the second cold-rolling process [Step 7] was subjected to an aging heat treatment process [Step 8], in which it was heat-treated at the temperature and holding time shown in Table 2. Then, a third cold-rolling process [Step 9] was performed, in which the material was rolled with the longitudinal direction being the rolling direction, under the conditions of the total processing rate shown in Table 2, to obtain a rolled material with a thickness of 0.20 mm.

[0072] In Table 1, among the constituent components other than copper (Cu) and Cr (chromium), Mg (magnesium), Sn (tin), Zn (zinc), Fe (iron), Si (silicon), and Zr (zirconium) were considered optional additives. Furthermore, in Table 1, a horizontal line "-" is indicated in the column for components not included in the alloy composition of the copper alloy material, indicating that the component is either not present or, if present, is below the detection limit.

[0073] [Various measurement and evaluation methods] The copper alloy plate materials according to the above-described examples and comparative examples of the present invention were used to perform the following property evaluations. The evaluation conditions for each property are as follows.

[0074] [1] Percentage of total area of ​​crystal grains oriented in Brass, S, and Copper orientations The ratio of the total area of ​​crystal grains oriented in the Brass, S, and Copper orientations was obtained from crystal orientation analysis data calculated using analysis software (TSL Corporation, 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) for copper alloy sheets obtained in the present invention example and comparative example. The measurements were performed on rolled surface samples of copper alloy sheets embedded in resin and finished with mechanical polishing and buffing (colloidal silica), with a scan step size of 0.2 μm in a field of view of approximately 1000 μm × 1000 μm.

[0075] From the crystal orientation analysis data obtained by the EBSD method, {011} <211> Brass direction, {123} <634> The S direction and {112} <111> The atomic planes of crystal grains with deviation angles of 10° or less from each of the Copper orientations were determined as the atomic planes of crystal grains oriented in the Brass orientation, S orientation, and Copper orientation, respectively. By dividing these areas by the area of ​​the measurement region (measurement area), the proportion of the area of ​​crystal grains oriented in the Brass orientation (a), the proportion of the area of ​​crystal grains oriented in the S orientation (b), the proportion of the area of ​​crystal grains oriented in the Copper orientation (c), and the proportion of the total area of ​​crystal grains oriented in the Brass, S, and Copper orientations (a+b+c) were determined. The results are shown in Table 3.

[0076] [2] Percentage of the area of ​​crystal grains oriented in the cubic direction The proportion of the area of ​​crystal grains oriented in the Cube orientation was obtained from crystal orientation analysis data calculated using analysis software (TSL Corporation, 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), similar to the proportion of the total area of ​​crystal grains oriented in the Brass, S, and Copper orientations described above. At this time, from the crystal orientation analysis data, {001} <100> The atomic planes of crystal grains with a deviation angle of 10° or less from the Cube orientation were considered as the atomic planes of crystal grains oriented in the Cube orientation. The area of ​​these planes was determined, and by dividing these areas by the measured area, the proportion of the area of ​​crystal grains oriented in the Cube orientation was calculated. The results are shown in Table 3.

[0077] [3] Average grain size of crystal grains on the rolled surface The average grain size of the crystal grains on the rolled surface of the copper alloy sheet was determined by the cutting method specified in JIS H0501. More specifically, the rolled surface of the copper alloy sheet was polished to a mirror finish by wet polishing and buffing, and the polished surface was etched with a weak acid solution for several seconds. The surface was then observed at 500x magnification using an optical microscope (OM). In the resulting optical microscope (OM) image, ten line segments corresponding to a length of 100 μm (line segments with a length of 50 mm in the optical microscope image) were drawn parallel to each other along the rolling direction. The total number of points where each line segment intersects with the crystal grain boundary was counted, and the average length of each section of the line segment demarcated by the crystal grain boundary was calculated using the following formula (I). The average grain size (μm), which is the average length of each section of the line segment, was then determined. The results are shown in Table 3. Average length of each section of the line segment [μm] = 100 [μm] × 10 / (total number of intersections between the line segment and grain boundaries) ... (I)

[0078] [4] Evaluation of the drawability of copper alloy sheet material To test the drawability of the copper alloy sheet, a 40mm diameter blank was formed by press punching from the obtained 0.2mm thick copper alloy sheet. A lubricant (product name: Preton R-303P, manufactured by Sugimura Chemical Industry Co., Ltd.) was applied to the surface of the blank, and it was mounted on a die with a shoulder radius of curvature of 1mm. A punch with a cylindrical shape, a tip diameter of 20mm, a tip corner radius of curvature of 1mm, and a punch-to-die clearance of 0.27mm was pressed into the center of the blank, and a single draw process was performed to obtain a cylindrical cup as a drawn product.

[0079] For the obtained drawn product, as shown in Fig. 1(a), a line segment L1 was drawn from the center C of the bottom surface 11 of the drawn product 1 to one side of the rolling direction X of the copper alloy plate forming the bottom surface, and this line segment L1 was used as the reference for the angle (0°). Also, for the side surface 12 of the drawn product 1 at the position where this line segment L1 abuts, the height from the bottom surface 11 to the edge 13 was measured, and this height was designated as H0. Next, a line segment L2 was drawn from the center C of the bottom surface 11 of the drawn product 1 in a direction forming an angle of 45° clockwise with respect to the line segment L1, and for the side surface 12 of the drawn product 1 at the position where this line segment L1 abuts, the height from the bottom surface 11 to the edge 13 was measured, and this height was designated as H 45 . Similarly, line segments L3 - L8 were drawn from the center C in directions forming angles of 90°, 135°, 180°, 225°, 270°, 315° counterclockwise with respect to the line segment L1. For the side surface 12 of the drawn product 1 at the positions where these line segments L3 - L8 abut, as shown in Fig. 1(b), the height from the bottom surface 11 to the edge 13 was measured respectively, and these heights were designated as H 90 、H 135 、H 180 、H 225 、H 270 、H 315 respectively.

[0080] Using these heights H0, H 45 、H 90 、H 135 、H 180 、H 225 、H 270 、H 315 , the size E [%] of the undulation (ear) at the edge of the drawn product was calculated from the following formulas (II) - (IV). That is, in this embodiment, as the size E of the undulation (ear), when the average of the heights of the side surface 12 of the drawn product 1 at the positions where the line segments L1 - L8 abut is taken as 100%, the ratio [%] of the difference between the average of the heights of the side surface 12 in the directions forming angles of 0°, 90°, 180°, 270° with respect to the rolling direction X from the center C and the average of the heights of the side surface 12 in the directions forming angles of 45°, 135°, 225°, 315° with respect to the rolling direction X was determined. H1=(H 45 +H 135 +H 225 +H 315) / 4 ···(II) H2=(H0+H 90 +H 180 +H 270 ) / 4 ···(III) E=[(H1−H2) / {(H1+H2) / 2}]×100 ···(IV)

[0081] In this case, if the ears are formed at angles of approximately 45°, 135°, 225°, and 315° with respect to the rolling direction, the ear size E will be a positive number, and if the ears are formed at angles of approximately 0°, 90°, 180°, and 270° with respect to the rolling direction, the ear size E will be a negative number.

[0082] Furthermore, the size of the undulation (edge) at the edge of the drawn product was evaluated according to the following evaluation criteria. These criteria were established based on the fact that the greater the absolute value of the edge size E, the lower the drawability, and in particular, when the absolute value of the edge size E is greater than 6.0%, cracks are more likely to occur from the edge during the drawing process. The results are shown in Table 3.

[0083] <Evaluation criteria for the size of the undulation (edge) at the edge of a drawn product> "1" (Excellent): When the absolute value of ear size E is 2.0% or less. "2" (Good): When the absolute value of ear size E is greater than 2.0% and less than or equal to 6.0%. "3" (Not acceptable): If the absolute value of the ear size E exceeds 6.0%, or if the blank breaks during the drawing process.

[0084] [5] Evaluation of the bendability of copper alloy sheet material The bendability of copper alloy sheets was evaluated by taking a 25 mm long and 10 mm wide test piece from the copper alloy sheet so that the rolling direction of the base material was in the longitudinal direction. The obtained test piece was then pre-bent in the badway direction using a 90° bending die with a bending angle of 90 degrees and a bending radius of 0.4 mm, according to the Japan Brass and Copper Association Technical Standard T307:2007 (Method for Evaluating the Bendability of Copper and Copper Alloy Sheets and Strips). After that, a compression test was performed using a compression tester to perform a tight bend in the badway direction. The presence or absence of cracks and wrinkles on the outside of the bent portion was observed visually with an optical microscope. The bendability was evaluated based on the observation results according to the Japan Brass and Copper Association Technical Standard T307:2007.

[0085] More specifically, the bendability of copper alloy sheets was evaluated according to the following evaluation criteria. The results are shown in Table 3. "1" (Excellent): The evaluation criteria according to the Japan Brass Copper Association Technical Standard T307:2007 are A or B. "2" (Good): When the evaluation criterion according to the Japan Copper Spinning Association Technical Standard T307:2007 is C. "3" (Not acceptable): If the evaluation criterion according to the Japan Brass Copper Association Technical Standard T307:2007 is D or E. In other words, if a crack is found on the outside of the bent section.

[0086] [6] Overall rating Regarding the two evaluation results for the draw-forming and bend-forming properties of copper alloy sheets, if both were rated "1", it was evaluated as "1" (Excellent), indicating that both draw-forming and bend-forming properties were superior. Furthermore, if one of these evaluation results was rated "1" and the other "2", it was evaluated as "2" (Good), indicating that both draw-forming and bend-forming properties were at least good. On the other hand, if at least one of these two evaluation results was rated "3", it was evaluated as "3" (Unacceptable), indicating that at least one of the draw-forming or bend-forming properties was unacceptable. The results are shown in Table 3.

[0087] [Table 1]

[0088] [Table 2]

[0089] [Table 3]

[0090] From the results in Tables 1 to 3, the copper alloy sheet materials of Examples 1 to 16 of the present invention had an alloy composition within the appropriate range for the present invention, and the proportion of the total area of ​​crystal grains oriented in the Brass, S, and Copper orientations was in the range of 25% to 38%, and the proportion of the area of ​​crystal grains oriented in the Cube orientation was 12% or more. In this case, both the evaluation of bendability and the evaluation of deep drawing ability were evaluated as "1" or "2".

[0091] Therefore, the copper alloy sheet materials of Examples 1 to 16 of the present invention have excellent bendability and excellent deep drawing properties, and in particular, it was possible to reduce the size of the edges formed on the deep-drawn products.

[0092] Of these, Examples 1 to 5 of the present invention are examples in which the conditions for the temperature reached and holding time of intermediate annealing in the first intermediate annealing process [step 4] and the second intermediate annealing process [step 6], and the conditions for the total processing rate in the first cold rolling process [step 5] are changed within the range described above. Since the copper alloy sheet materials of Examples 1 to 5 of the present invention were evaluated as "1" or "2" for both bendability and deep drawing, it is considered that changing these conditions within the range described above will have little effect on the evaluation results of bendability and deep drawing.

[0093] Furthermore, Example 6 of the present invention is an example in which the total processing rate in the second cold rolling process [process 7] is high at 33%. The copper alloy sheet material of Example 6 of the present invention has a higher proportion of the area of ​​crystal grains oriented in the S direction (b) than other examples of the invention, and therefore its deep drawing processability was evaluated as "2".

[0094] Furthermore, Example 7 of the present invention is an example in which the total processing rate in the third cold rolling process [process 9] is high at 30%. The copper alloy sheet material of Example 7 of the present invention had a lower proportion of crystal grains oriented in the Cube orientation compared to other examples of the invention, and therefore its bendability was evaluated as "2".

[0095] In the copper alloy sheet materials of Examples 8 to 11 of the present invention, the average grain size of the crystal grains contained in the rolled surface was reduced, and the proportion of the area of ​​crystal grains oriented in the Cube orientation increased, resulting in both the evaluation of bendability and the evaluation of deep drawing being rated as "1". This was achieved by optimizing the intermediate annealing conditions in the first intermediate annealing process [Step 4] and the second intermediate annealing process [Step 6], and the total processing rate in the first cold rolling process [Step 5], the second cold rolling process [Step 7], and the third cold rolling process [Step 9].

[0096] Furthermore, although the copper alloy sheet materials of Examples 11 to 16 of the present invention contain one or more optional additives, even in such cases, if the total content of the optional additives is in the range of 0.05% by mass or more and 1.00% by mass or less, the bendability and drawability were at least good.

[0097] On the other hand, in all of the copper alloy sheets of Comparative Examples 1 to 9, the proportion of the total area of ​​crystal grains oriented in the Brass, S, and Copper orientations exceeded 38%, and the proportion of the area of ​​crystal grains oriented in the Cube orientation was less than 12%. Therefore, the copper alloy sheets of Comparative Examples 1 to 9 were evaluated as "3" in either the evaluation of bendability or the evaluation of deep drawing ability, or both.

[0098] In particular, the copper alloy sheet material of Comparative Example 1 had a low temperature reached in the first intermediate annealing process [step 4], and its bendability was rated as "3".

[0099] Furthermore, the copper alloy sheet material of Comparative Example 2 had a high temperature reached during the second intermediate annealing process [step 6], and both its bendability and drawability were evaluated as "3".

[0100] Furthermore, in Comparative Examples 3 and 4, the total processing rate conditions in the first cold rolling process [process 5] were outside the preferred range described above, and both the bendability and drawability were evaluated as "3".

[0101] Furthermore, the copper alloy sheet material of Comparative Example 5 had a long holding time at the achieved temperature in the first intermediate annealing process [step 4], and both its bendability and deep drawing properties were evaluated as "3".

[0102] Furthermore, the copper alloy sheet material of Comparative Example 6 had a long holding time at the target temperature in the first intermediate annealing process [step 4] and a short holding time at the target temperature in the second intermediate annealing process [step 6], resulting in a drawing processability evaluation of "3".

[0103] Furthermore, the copper alloy sheets of Comparative Examples 7 and 8 had a total processing rate outside the preferred range described above in the third cold rolling process [process 9], and both their bendability and drawability were evaluated as "3".

[0104] Furthermore, the copper alloy sheet material of Comparative Example 9 had a large total processing rate in the second cold rolling process [process 7], and its deep drawing processability was evaluated as "3". [Explanation of symbols]

[0105] 1. Draw-formed product 11 Bottom surface of a drawn product 12 Side view of a drawn product 13 Edge of a drawn product C Center of the bottom surface of the drawn product H0, H 45 H 90 H 135 H 180 H 225 H 270 H 315 Height from the base to the rim Line segments to be drawn on the bottom surface of L1-L8 drawn products X Rolling direction of copper alloy sheet

Claims

1. A copper alloy plate material having an alloy composition in which Cr is contained in a range of 0.10% by mass or more and 1.00% by mass or less, with the remainder being Cu and unavoidable impurities, In the crystal orientation analysis performed by the EBSD method on the measurement area of ​​the rolled surface of the aforementioned copper alloy sheet, The total area of ​​the crystal grains oriented in the Brass orientation {011}<211>, the S orientation {123}<634>, and the Copper orientation {112}<111> respectively is in the range of 25% to 38% of the area of ​​the measurement region, and A copper alloy plate material in which the area of ​​crystal grains oriented in the {001}<100> cube orientation accounts for 12% or more of the area of ​​the measurement region.

2. The copper alloy sheet material according to claim 1, wherein the average grain size of the crystal grains on the rolled surface is 15 μm or less.

3. The copper alloy sheet material according to claim 1, wherein the alloy composition further contains at least one optional additive selected from the group consisting of Mg, Sn, Zn, Fe, Si, and Zr, in a total amount of 0.05% by mass or more and 1.00% by mass or less.

4. A copper alloy sheet material according to any one of claims 1 to 3, used as a raw material for deep drawing.

5. A drawn product obtained by drawing a copper alloy sheet material according to any one of claims 1 to 3.

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