Copper alloy sheet material, copper alloy sheet material for drawing processing, and drawn article

Abstract

The invention provides a copper alloy sheet material, a copper alloy sheet material for drawing, and a drawn article, which have high tensile strength and high conductivity and can obtain excellent drawability. The copper alloy sheet has an alloy composition containing Ni in the range of 1.00 mass% or more and 5.00 mass% or less and Si in the range of 0.20 mass% or more and 1.30 mass% or less, with the balance made up of Cu and unavoidable impurities, and is characterized in that: the copper alloy sheet has an alloy composition containing Ni in the range of 1.00 mass% or more and 5.00 mass% or less and Si in the range of 0.20 mass% or more and 1.30 mass% or less; wherein the average value of the alpha-fiber orientation density in at least the plate surface of the copper alloy plate obtained by crystal orientation analysis according to the EBSD method is 3.0 or less, the tensile strength is in the range of 500-900 MPa, and the conductivity is 30% IACS or more.

Description

Technical Field

[0001] The present invention relates to a copper alloy sheet, a copper alloy sheet for deep drawing, and a deep drawn part. Background Art

[0002] Copper alloy sheets are used, for example, in connectors, lead frames, relays, switches, sockets, shielding cases, shielding cans, camera module cases, vibration device housings, heat dissipation parts of liquid crystal and organic EL (electroluminescence) displays, connectors, shielding cases, shielding cans, etc. for electric and electronic machines or electronic parts, and are often subjected to stamping processes such as blanking, bending, deep drawing, and bulging.

[0003] As a copper alloy sheet for such stamping processes, for example, Patent Document 1 discloses a copper alloy sheet having the following alloy composition: containing 0.3 to 1.9% by mass of Co and 0.1 to 0.5% by mass of Si, with the balance being composed of Cu and unavoidable impurities; the total ratio of special grain boundaries Σ7 grain boundaries and Σ9 grain boundaries obtained from the results measured by the electron backscatter diffraction (EBSD) method in all grain boundaries is 1.5% or more, Σ9 / Σ7 is 1.0 to 5.0, and the orientation density of the α-fiber (α-fiber, φ1 = 0° to 45°) satisfies the range of 3.0 or more and 25.0 or less. In Patent Document 1, by controlling the Σ7, 9 grain boundaries and α-fiber (φ1 = 0° to 45°) in the Cu-Co-Si-based copper alloy, the variation height of the boundary line between the edge (surface) and the shear surface during stamping is suppressed, and thereby the stamping blanking processability can be improved.

[0004] In addition, Patent Document 2 discloses a copper alloy sheet for electric and electronic machines having the following alloy composition: containing 3.5 to 25% by mass of Ni and 0.1 to 9.5% by mass of Sn, with the balance being composed of Cu and unavoidable impurities; the copper alloy sheet has a rolled texture; and Patent Document 2 also discloses a copper alloy sheet in which the average value of the orientation density of the α-fiber (φ1 = 0° to 45°) obtained from the texture analysis based on EBSD of the rolled texture is in the range of 2.5 or more and 30.0 or less, and the average value of the orientation density of the β-fiber (φ2 = 45° to 90°) is in the range of 2.5 or more and 30.0 or less. In Patent Document 2, by appropriately controlling the orientation densities of the α-fiber and β-fiber of the Cu-Ni-Sn alloy, the Young's modulus and its anisotropy can be reduced and made at a high level, and thereby, regardless of the direction in which the product is taken from the material, a specified spring characteristic can be stably obtained.

[0005] [Prior Art Documents]

[0006] (Patent Documents)

[0007] Patent Document 1: International Publication No. WO 2018 / 198995

[0008] Patent Document 2: Japanese Patent Application Laid-Open No. 2017-160513 Summary of the Invention

[0009] [Problems to be Solved by the Invention]

[0010] In recent years, with the increase in current and miniaturization of electronic devices and electronic components, higher mechanical properties and electrical conductivity (or thermal conductivity) have been gradually required for stamping products, which are one of the components constituting these. In particular, a copper alloy sheet is being sought, which is composed of a material capable of having both higher mechanical properties and electrical conductivity (or thermal conductivity) than brass and nickel silver, which are copper alloys conventionally used in deep-drawn parts for electronic devices and electronic components, such as connectors, lead frames, relays, switches, sockets, shielding cases, shielding cans, camera modules, heat dissipation parts for liquid crystal and organic EL displays, batteries, and connectors, shielding cases, and shielding cans for automotive in-vehicle use.

[0011] Here, the so-called "deep drawing" is a kind of metal sheet forming method, typically referring to a processing method in which a punch is pressed into a thin sheet of metal to form various shaped bottomed containers such as cylinders, square cylinders, and cones. In addition, the so-called "deep-drawn part" means a processed product formed by deep drawing, characterized in that the formed processed product does not have a joint point. In addition, the "deep-drawn part" also includes processed products formed by using other processing methods different from deep drawing (such as bending processing, crushing processing, twisting processing, etc.) in combination with deep drawing.

[0012] Generally, when deep drawing is performed, the closer to the edge of the deep-drawn part, the greater the force of compression deformation of the material and the more the metal mold floats, so that the thickness of the deep-drawn part becomes thicker more easily. On the other hand, the vicinity of the tip of the punch pressed in during deep drawing is stretched due to the load when the punch is pressed in, so that a reduction in plate thickness occurs. In particular, for materials that are likely to have a reduction in plate thickness in the vicinity of the tip of the punch, the thickness of the obtained deep-drawn part will vary, so it is difficult to finish machining the thickness of the deep-drawn part within a specified tolerance.

[0013] Here, in order to finish machining the thickness of the drawn part within a specified tolerance, it is necessary to thicken the sheet material before machining in such a way that the thickness is not less than a specified value near the front end of the punch for the drawn part, and then perform the drawing process. In addition, when thickening the sheet material before machining, it is also necessary to perform ironing on the drawn part to align the thickness of the part near the edge of the drawn part with the thickness near the front end of the punch to adjust the thickness of the drawn part. However, when using a material that is prone to a reduction in sheet thickness near the front end of the punch or when thickening the sheet material before machining, the ironing thickness becomes larger during the ironing process, so the material is prone to fracture. Therefore, there is a need for a copper alloy sheet that has excellent drawability. More specifically, the sheet thickness near the front end of the punch is not easily reduced during the drawing process.

[0014] In this regard, although Patent Document 1 describes an improvement in the stamping and blanking properties of a copper alloy sheet, it does not discuss the drawability of the copper alloy sheet at all, nor does it disclose excellent drawability combined with high tensile strength and high electrical conductivity, nor does it show the evaluation results of these properties.

[0015] In addition, although Patent Document 2 describes an improvement in the spring properties of a copper alloy sheet, it does not discuss the drawability of the copper alloy sheet at all. In addition, the copper alloy sheet of Patent Document 2 is composed of a Cu-Ni-Sn alloy, but the electrical conductivity is preferably even higher. It does not disclose excellent drawability combined with high tensile strength and high electrical conductivity, nor does it show the evaluation results of these properties.

[0016] Therefore, the present invention has been completed in view of the above problems, and the object is to provide a copper alloy sheet, a copper alloy sheet for drawing, and a drawn part that have high tensile strength and high electrical conductivity and can obtain excellent drawability.

[0017] [Technical means for solving the problem]

[0018] The present inventors have found a copper alloy sheet having the following alloy composition: containing Ni in the range of 1.00 mass% or more and 5.00 mass% or less, Si in the range of 0.20 mass% or more and 1.30 mass% or less, and the balance being composed of Cu and unavoidable impurities; wherein, the average value of the orientation density of the α fiber in at least the sheet surface of the copper alloy sheet obtained by crystal orientation analysis according to the SEM-EBSD method is set to 3.0 or less, and the tensile strength is set in the range of 500 MPa or more and 900 MPa or less, and the electrical conductivity is set to 30% IACS or more. Thereby, the tensile strength and electrical conductivity of the copper alloy sheet can be improved, and the drawability can be improved. In particular, the reduction in the sheet thickness near the front end of the punch can be suppressed during the drawing process, thus completing the present invention.

[0019] (1) A copper alloy sheet has the following alloy composition: containing Ni in the range of 1.00% by mass or more and 5.00% by mass or less, Si in the range of 0.20% by mass or more and 1.30% by mass or less, and the balance is composed of Cu and unavoidable impurities; wherein, the average value of the orientation density of the α fiber in at least the plate surface of the copper alloy sheet obtained by crystal orientation analysis according to the EBSD method is 3.0 or less, the tensile strength is in the range of 500 MPa or more and 900 MPa or less, and the conductivity is 30% IACS or more.

[0020] (2) The copper alloy sheet according to the above (1), wherein, regarding the aggregation of crystal planes facing the normal direction (ND) of the plate surface obtained by the above crystal orientation analysis, the ratio of the area of the region having crystal planes with an angle of 10° or less between the normal direction (ND) and the normal direction of the (100) plane to the area of the measurement region of the plate surface is 10% or less.

[0021] (3) The copper alloy sheet according to the above (1) or (2), wherein the above alloy composition further contains at least one optional additive component selected from the group consisting of Sn, Zn, Mg, Fe, and Cr in a total amount in the range of 0.10% by mass or more and 1.00% by mass or less.

[0022] (4) A copper alloy sheet for drawing is composed of the copper alloy sheet according to any one of the above (1) to (3).

[0023] (5) A drawn part is obtained by drawing the copper alloy sheet according to any one of the above (1) to (3).

[0024] [Advantages of the Invention]

[0025] According to the present invention, it is possible to provide a copper alloy sheet, a copper alloy sheet for drawing, and a drawn part, which have high tensile strength and high conductivity, and can obtain excellent drawability. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a schematic diagram showing a main part of an example of a processing machine used in the repeated bending process among the steps of manufacturing the copper alloy sheet of the present invention.

[0027] Figure 2 It is a diagram for explaining a method of measuring the plate thickness near the tip of a punch. DETAILED DESCRIPTION OF THE INVENTION

[0028] Next, embodiments of the present invention will be described. The following description is only an example showing the embodiments in the present invention and is not intended to limit the scope of the patent application.

[0029] The copper alloy sheet according to the present invention is a copper alloy sheet having the following alloy composition: Ni in the range of 1.00% by mass or more and 5.00% by mass or less, Si in the range of 0.20% by mass or more and 1.30% by mass or less, and the balance being composed of Cu and unavoidable impurities; wherein, the average value of the orientation density of the α fiber in at least the sheet surface of the copper alloy sheet obtained by crystal orientation analysis according to the EBSD method is 3.0 or less, the tensile strength is in the range of 500 MPa or more and 900 MPa or less, and the conductivity is 30% IACS or more.

[0030] The copper alloy sheet of the present invention reduces the orientation density of the α fiber in at least the sheet surface to 3.0 or less by containing appropriate amounts of Ni and Si respectively and manufacturing under appropriate manufacturing conditions, thereby suppressing the reduction in sheet thickness near the tip of the punch of the drawn part. In addition, the copper alloy sheet of the present invention can improve the tensile strength and conductivity of the copper alloy sheet by containing appropriate amounts of Ni and Si respectively. Therefore, with the copper alloy sheet of the present invention, a copper alloy sheet, a copper alloy sheet for drawing processing, and a drawn part can be provided, which have high tensile strength and high conductivity and can obtain excellent drawability.

[0031] [1] Alloy composition of copper alloy sheet

[0032] The copper alloy sheet of the present invention has the following alloy composition: Ni in the range of 1.00% by mass or more and 5.00% by mass or less, Si in the range of 0.20% by mass or more and 1.30% by mass or less, as essential components.

[0033] Hereinafter, the reasons for limiting the alloy composition of the copper alloy sheet will be described.

[0034] (Ni: 1.00% by mass or more and 5.00% by mass or less)

[0035] Ni (nickel) is an important component that has the effect of improving the tensile strength of copper alloy sheets, and Ni is contained in the range of 1.00 mass% or more and 5.00 mass% or less. Here, when the Ni content is less than 1.00 mass%, the desired high tensile strength cannot be obtained. In addition, if the Ni content is more than 5.00 mass%, it becomes easy to form a coarse second phase composed of a compound with Si, and this second phase easily becomes the starting point of cracks during deep drawing. In addition, if the Ni content is more than 5.00 mass%, the conductivity of the copper alloy sheet will decrease. Therefore, from the viewpoints of improving the tensile strength and conductivity of the copper alloy sheet and making the deep-drawn parts less likely to crack, the Ni content is in the range of 1.00 mass% or more and 5.00 mass% or less, preferably in the range of 1.00 mass% or more and 4.50 mass%, more preferably in the range of 1.50 mass% or more and 4.50 mass%, and even more preferably in the range of 2.00 mass% or more and 4.00 mass% or less. In particular, from the viewpoint of improving the conductivity of the copper alloy sheet, the Ni content is preferably 4.50 mass% or less.

[0036] (Si: 0.20 mass% or more and 1.30 mass% or less)

[0037] Si (silicon) is an important component that has the effect of improving the tensile strength of copper alloy sheets, and Si is contained in the range of 0.20 mass% or more and 1.30 mass% or less. Here, when the Si content is less than 0.10 mass%, the desired high tensile strength cannot be obtained. In addition, if the Si content is more than 1.30 mass%, it becomes easy to form a coarse second phase composed of a compound with Ni, and this second phase easily becomes the starting point of cracks during deep drawing. In addition, if the Si content is more than 1.30 mass%, the conductivity of the copper alloy sheet will decrease. Therefore, from the viewpoints of improving the tensile strength and conductivity of the copper alloy sheet and making the deep-drawn parts less likely to crack, the Si content is in the range of 0.20 mass% or more and 1.30 mass% or less, preferably in the range of 0.20 mass% or more and 1.10 mass% or less, more preferably in the range of 0.30 mass% or more and 1.10 mass% or less, and even more preferably in the range of 0.50 mass% or more and 1.00 mass% or less. In particular, from the viewpoint of improving the conductivity of the copper alloy sheet, the Si content is preferably 1.10 mass% or less.

[0038] <Optional additive components>

[0039] Furthermore, the copper alloy sheet of the present invention can further contain at least one optional additive component selected from the group consisting of Sn, Zn, Mg, Fe, and Cr in a total amount in the range of 0.10 mass% or more and 1.00 mass% or less.

[0040] (Sn: 0.10 mass % or more and 0.30 mass % or less)

[0041] Sn (tin) is a component that has the effect of improving stress relaxation characteristics. When such an effect is exerted, the Sn content is preferably set to 0.10 mass % or more. On the other hand, if the Sn content exceeds 0.30 mass %, there is a tendency for the conductivity to decrease. Therefore, the Sn content is preferably in the range of 0.10 mass % or more and 0.30 mass % or less.

[0042] (Zn: 0.10 mass % or more and 0.50 mass % or less)

[0043] Zn (zinc) is a component that has the effect of improving the adhesion and migration characteristics of Sn plating. When such an effect is exerted, it is preferable to set the Zn content to 0.10 mass % or more. On the other hand, if the Zn content exceeds 0.50 mass %, there is a tendency for the conductivity to decrease. Therefore, the Zn content is preferably in the range of 0.10 mass % or more and 0.50 mass % or less.

[0044] (Mg: 0.10 mass % or more and 0.30 mass % or less)

[0045] Mg (magnesium) is a component that has the effect of improving stress relaxation characteristics. When such an effect is exerted, it is preferable to set the Mg content to 0.10 mass % or more. On the other hand, if the Mg content exceeds 0.30 mass %, there is a tendency for the conductivity to decrease. Therefore, the Mg content is preferably in the range of 0.10 mass % or more and 0.30 mass % or less.

[0046] (Fe: 0.05 mass % or more and 0.30 mass % or less)

[0047] Fe (iron) is a component that has the following effects: the effect of suppressing grain coarsening after dynamic recrystallization in the following hot rolling step [Step 3], and the effect of preventing surface roughness of drawn parts. When such an effect is exerted, it is preferable to set the Fe content to 0.05 mass % or more. In addition, if the Fe content exceeds 0.30 mass %, large Fe-containing crystals are likely to be generated during casting, and it is easy to form the starting points of cracks. Therefore, the Fe content is preferably in the range of 0.05 mass % or more and 0.30 mass % or less.

[0048] (Cr: 0.05 mass % or more and 0.30 mass % or less)

[0049] Cr (chromium) is a component having the following effects: an effect of suppressing grain coarsening after dynamic recrystallization in the following hot rolling step [Step 3], and an effect of preventing surface roughness of drawn parts. When this effect is exerted, it is preferable to set the Cr content to 0.05% by mass or more. In addition, if the Cr content exceeds 0.30% by mass, large Cr-containing crystals are likely to be generated during casting, and it is easy to form the starting points of cracks. Therefore, the Cr content is preferably in the range of 0.05% by mass or more and 0.30% by mass or less.

[0050] (Total content of optional additive components: 0.10% by mass or more and 1.00% by mass or less)

[0051] In order to obtain the above effects obtained from the optional additive components, these optional additive components preferably contain a total of 0.10% by mass or more. On the other hand, if these optional additive components are contained in a large amount, the conductivity will decrease. Therefore, the total content of the optional additive components is preferably set to 1.00% by mass or less.

[0052] (Remainder: Cu and unavoidable impurities)

[0053] The copper alloy used to form the copper alloy sheet has the following alloy composition: In addition to the above components, the remainder is composed of Cu (copper) and unavoidable impurities. In addition, the so-called "unavoidable impurities" referred to here means an impurity that generally exists in raw materials in metal products and is unavoidably mixed in during the manufacturing process and is originally unnecessary, but since it is trace and does not affect the properties of the metal product, it is tolerable. Examples of the components that can be cited as unavoidable impurities include non-metallic elements such as sulfur (S), carbon (C), oxygen (O); and metal elements such as antimony (Sb). In addition, the upper limit of the content of these components can be set, for example: each of the above components is 0.05% by mass, and the total amount of the above components is 0.20% by mass.

[0054] [2] Average value of the orientation density of α fibers

[0055] The average value of the orientation density of the α-fiber in at least the plate surface of the copper alloy sheet obtained by crystal orientation analysis according to the EBSD method of the copper alloy sheet of the present invention is 3.0 or less. Here, if the average value of the orientation density of this α-fiber exceeds 3.0, the case where the sheet thickness decreases near the tip of the punch of the drawn part becomes likely. On the other hand, when the average value of the orientation density of this α-fiber is less than 0.5, the apex height of the undulation of the drawn part becomes low, so that it becomes difficult to form a bridge during continuous stamping. Therefore, the average value of the orientation density of the α-fiber is preferably set to 0.5 or more. In addition, when the bridge is not formed, the average value of the orientation density of the α-fiber may be less than 0.5. From the viewpoint of making it difficult for the sheet thickness to decrease near the tip of the punch of the drawn part, the average value of the orientation density of the α-fiber is preferably 2.8 or less, more preferably 2.3 or less, and still more preferably 2.0 or less. Therefore, the average value of the orientation density of the α-fiber is preferably in the range of 0.5 or more and 2.8 or less, more preferably in the range of 0.5 or more and 2.3 or less, and still more preferably in the range of 0.5 or more and 2.0 or less.

[0056] Here, the average value of the orientation density of the α-fiber can be obtained from the crystal orientation analysis data calculated using the analysis software (OIM Analysis manufactured by TSL Corporation) from the crystal orientation data continuously measured using the EBSD detector attached to the high-resolution scanning type analytical electron microscope (manufactured by JEOL Ltd., JSM-7001FA). In addition, the so-called "EBSD" is an abbreviation for Electron BackScatter Diffraction, and is a crystal orientation analysis technique using the reflection electron Kikuchi line diffraction (SEM) generated by irradiating an electron beam on a sample, that is, a copper sheet, in a scanning electron microscope (SEM). The so-called "OIM Analysis" is an analysis software for data measured by EBSD. The measurement can be performed on a cross-section along the rolling direction after filling the copper alloy sheet with resin and finishing it by mechanical grinding and polishing (colloidal silica). In addition, the measurement can also be performed on the plate surface of the copper alloy sheet after electrolytic polishing. The measurement regions in these cross-sections and plate surfaces are set to about 400 μm × 800 μm, and the measurement can be performed with a step size of 0.5 μm. When the above-mentioned field of view size cannot be obtained from the sample size during the measurement of both the cross-section and the plate surface, the value obtained by averaging the measurements in multiple fields of view can also be used.

[0057] When obtaining a crystal orientation distribution function (ODF) represented by Euler angles (φ1, φ, φ2) by setting measurement points with a reliability index CI value of 0.1 or more among the crystal orientation data obtained by the EBSD method as analysis targets, for the orientation of the α fiber in the range of 0 to 35° for φ1, the average value of the ODF intensity with respect to a random orientation sample as a reference (reference value = 1) is obtained as the average value of the orientation density of the α fiber.

[0058] [3] The area ratio of the region having a crystal plane with an angle between the normal direction (ND) of the plate surface and the normal direction of the (100) plane within 10°

[0059] The copper alloy sheet of the present invention is preferably such that, with respect to the aggregation of crystal planes facing the normal direction (ND) of the plate surface obtained by crystal orientation analysis according to the EBSD method, the area ratio of the region having a crystal plane with an angle between the normal direction (ND) of the plate surface and the normal direction of the (100) plane within 10° to the area of the measurement region of the plate surface is 10% or less. Here, when the area ratio of the region with an angle difference between the normal direction (ND) of the plate surface and the normal of the (100) plane within 10° to the area of the measurement region of the plate surface is greater than 10%, it becomes easy for the sheet thickness to decrease near the tip of the punch of the drawn part. The reason is that in materials where the (100) plane of the crystal is oriented on or near the plate surface, during the flange deformation of the drawing process, it is difficult to undergo compressive deformation due to the characteristics of crystal slip deformation, so a greater force is required for flange deformation. As a result, it may become easy for the sheet thickness to decrease near the tip of the punch that pulls the load of the drawing process.

[0060] Here, the area of the region having a crystal plane with an angle between the normal direction (ND) of the plate surface and the normal direction of the (100) plane within 10° can be obtained by the following method: setting measurement points with a reliability index CI value of 0.1 or more among the crystal orientation data obtained by the above EBSD method as analysis targets, and calculating the proportion of the area of the region of the crystal plane (atomic plane) with an angle between the normal of the (100) plane and the normal direction (ND) of the plate surface within 10° in the area of the measurement region.

[0061] [4] Tensile strength of the copper alloy sheet

[0062] The tensile strength of the copper alloy sheet of the present invention is in the range of 500 MPa or more and 900 MPa or less. Thereby, even when the copper alloy sheet is used for small parts and thin parts such as electrical / electronic parts and in-vehicle parts for automobiles, a desired tensile strength can still be obtained, and thus the copper alloy sheet can be suitably used for various drawn parts. On the other hand, if the tensile strength exceeds 900 MPa, the fracture resistance of the copper alloy sheet also increases, but the deformation resistance during deep drawing also becomes high, and the sheet thickness reduction rate in the deep drawing test tends to be high. Therefore, the tensile strength of the copper alloy sheet is in the range of 500 MPa or more and 900 MPa or less, and preferably in the range of 550 MPa or more and 900 MPa or less. Here, as the tensile strength, for example, the tensile strength when stretching in the direction parallel to the rolling direction can be cited. In addition, the measurement of the tensile strength is carried out using two test pieces of No. 13B specified in Japanese Industrial Standard (JIS) Z2241, and the average value of the tensile strengths obtained from the two test pieces is set as the measured value of the tensile strength. The test pieces are cut in such a way that the direction parallel to the rolling direction becomes the long side direction.

[0063] In particular, from the viewpoint of further improving the deep drawability by further reducing the sheet thickness reduction rate in the deep drawing test, it is preferable that the average value of the orientation density of the α fibers of the copper alloy sheet is in the range of 0.5 or more and 2.3 or less, and the tensile strength of the copper alloy sheet is in the range of 780 MPa or more and 900 MPa or less.

[0064] [5] Conductivity of the copper alloy sheet

[0065] The conductivity of the copper alloy sheet of the present invention is 30% IACS or more. Thereby, the copper alloy sheet has high conductivity, and thus the copper alloy sheet can also be used for drawn parts that require electromagnetic wave shielding properties or heat dissipation properties. Therefore, the conductivity of the copper alloy sheet is 30% IACS or more, and preferably 35% IACS or more. Here, the measurement of the conductivity (International Annealed Copper Standard (IACS)) is carried out twice using the four-terminal method, and the average value of the conductivities obtained from the two measurements is set as the measured value of the conductivity.

[0066] [6] An example of the manufacturing method of the copper alloy sheet

[0067] The above-mentioned copper alloy sheet can be realized by combining the control of the alloy composition and the process, and the process is not particularly limited. Among them, as an example of a process having such a high tensile strength and capable of obtaining excellent deep drawability, the following method can be cited.

[0068] An example of the method for manufacturing a copper alloy sheet of the present invention is to perform at least sequentially on a copper alloy material having an alloy composition equivalent to the alloy composition of the above-mentioned copper alloy sheet: a melting and casting step [Step 1], a reheating step [Step 2], a hot rolling step [Step 3], a first cold rolling step [Step 4], an intermediate annealing step [Step 5], a repeated bending process step [Step 6], a melting treatment step [Step 7], an aging heat treatment step [Step 8], a second cold rolling step [Step 9], and a low-temperature annealing step [Step 10].

[0069] (i) Melting and casting step [Step 1]

[0070] The melting and casting step [Step 1] is to melt a copper alloy material having an alloy composition equivalent to the above alloy composition and cast it to produce an ingot (billet) of a specified shape (for example, thickness 30 mm, width 100 mm, length 150 mm). The melting and casting step [Step 1] is preferably: using a high-frequency melting furnace to melt and cast the copper alloy material in the atmosphere, an inert gas environment, or a vacuum. In addition, although the alloy composition of the copper alloy material varies depending on the added components in each manufacturing step, it may sometimes adhere to the melting furnace or volatilize and may not be exactly the same as the alloy composition of the manufactured copper alloy sheet, but has an alloy composition substantially the same as that of the copper alloy sheet.

[0071] (ii) Reheating step [Step 2]

[0072] The reheating step [Step 2] is a step of performing heat treatment on the ingot after performing the casting step [Step 1]. The conditions for the heat treatment in the reheating step [Step 2] are preferably: the reaching temperature (heat treatment temperature) is in the range of 900 °C or more and 1050 °C or less, and the holding time (heat treatment time) at the reaching temperature is in the range of 1 hour or more and 10 hours or less. Here, when the reaching temperature is lower than 900 °C, coarse precipitates are generated due to temperature drop when entering the following hot rolling step [Step 3], the solid solubility decreases in the melting treatment step [Step 7], and the precipitation strengthening amount in the aging heat treatment step [Step 8] decreases, so it becomes difficult to obtain a copper alloy sheet having a high tensile strength. On the other hand, when the reaching temperature exceeds 1050 °C, the grain boundaries become weak, so the hot-rolled material after performing the hot rolling step [Step 3] is likely to crack.

[0073] (iii) Hot rolling step [Step 3]

[0074] The hot rolling step [Step 3] is a step of performing hot rolling on the ingot after the reheating step [Step 2] until it reaches a specified thickness to produce a hot-rolled material. The conditions of the hot rolling step [Step 3] can be set under the conditions for dynamic recrystallization to occur. For example, the rolling temperature can be set at 700 °C or higher, and the total processing rate (total reduction rate) can be set at 50% or higher. On the other hand, when dynamic recrystallization does not occur sufficiently in the hot rolling step [Step 3], the obtained copper alloy sheet is likely to have a non-uniform structure.

[0075] The "processing rate" (reduction rate) in this specification is a 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, as shown in the following formula.

[0076] [Processing rate] = {([Cross-sectional area before rolling] - [Cross-sectional area after rolling]) / [Cross-sectional area before rolling]} × 100 (%)

[0077] As an example, when the rolling temperature in the hot rolling step [Step 3] is 700 °C, the total amount of the processing rate calculated based on the cross-sectional area before the start of rolling and the cross-sectional area after one operation completed until reaching 700 °C can be set as the total processing rate (total reduction rate), and the total processing rate (total reduction rate) in the temperature range from the heat treatment temperature to 700 °C in the reheating step [Step 2] can be set at 50% or higher.

[0078] In addition, the temperature of the ingot during the hot rolling step [Step 3] can be measured with a radiation thermometer.

[0079] The hot-rolled material after the hot rolling step [Step 3] is preferably cooled. Here, the means for cooling the hot-rolled material is not particularly limited. For example, from the viewpoint of not easily causing grain coarsening, a means of increasing the cooling rate as much as possible is preferred. For example, it is preferred to set the cooling rate at 10 °C / second or higher by means of water cooling or the like.

[0080] Here, surface machining for shaving the surface can be performed on the cooled hot-rolled material. By performing surface machining, the surface oxide film and defects generated in the hot working step [Step 3] can be removed. The conditions for surface machining can be the conditions for normal machining and are not particularly limited. The amount shaved from the surface of the hot-rolled material by surface machining can be appropriately adjusted according to the conditions of the hot working step [Step 3]. For example, it can be set to about 1 mm to 5 mm from the surface back of the hot-rolled material.

[0081] (iv) The first cold rolling step [Step 4]

[0082] The first cold rolling step [Step 4] is a step of performing cold rolling on the hot-rolled material after the hot working step [Step 3]. The rolling in the first cold rolling step [Step 4] can be carried out at an arbitrary reduction rate in accordance with the plate thickness of the product. For example, the total processing rate can be set in the range of 70.0% or more and 99.9% or less.

[0083] (v) Intermediate annealing step [Step 5]

[0084] The intermediate annealing step [Step 5] is a step of performing heat treatment on the cold-rolled material after the first cold rolling step [Step 4] according to the alloy composition.

[0085] From the viewpoint of efficiently recovering the dislocations generated in the cold-rolled material, the annealing conditions in the intermediate annealing step [Step 5] are preferably as follows: the reaching temperature is in the range of 600°C or more and 800°C or less, and the holding time at the reaching temperature is in the range of 10 seconds or more and 1 hour or less. Here, when the reaching temperature is lower than 600°C, NiSi compounds will precipitate, resulting in an area where the angle between the normal direction of the plate surface (ND) and the normal direction of the (100) plane is within 10° on at least the plate surface of the copper alloy sheet in the following melting treatment step [Step 7]. In particular, from the viewpoint of further improving the deep drawability of the copper alloy sheet, the reaching temperature in the intermediate annealing step [Step 5] is preferably 650°C or more. On the other hand, in order to recover the dislocations generated in the cold-rolled material, the reaching temperature in the intermediate annealing step [Step 5] is sufficient at 800°C. From the viewpoint of productivity, heat treatment at a temperature higher than the above temperature is not ideal.

[0086] In addition, when the holding time at the reaching temperature in the intermediate annealing step [Step 5] is less than 10 seconds, the recovery of the dislocations generated in the cold-rolled material is likely to be insufficient. On the other hand, in order to recover the dislocations generated in the cold-rolled material, the holding time at the reaching temperature in the intermediate annealing step [Step 5] is sufficient at 1 hour. From the viewpoint of productivity, heat treatment for a longer time is not ideal.

[0087] Preferably, after performing the intermediate annealing step [Step 5], the cold-rolled material is cooled from the reaching temperature of the intermediate annealing step [Step 5] to a temperature at which new precipitation is not likely to occur, that is, a temperature of 300°C or less. At this time, the cooling of the cold-rolled material is preferably carried out at a cooling rate of 1°C / s or more. By increasing the cooling rate, the precipitation strengthening of the cold-rolled material is less likely to progress, so it is easy to repeatedly perform bending processing on the cooled cold-rolled material.

[0088] (vi) Repeated bending processing step [Step 6]

[0089] The repeating bending process step [Step 6] is a step of repeating the bending process on the cold-rolled material after performing the intermediate annealing step [Step 5]. More specifically, it is a step of alternately repeating the bending process from both plate surface sides of the cold-rolled material. For example, it can be performed by the following method: using a processing machine 1 as shown in Figure 1 , pressing the work rolls 2 alternately from both plate surface sides of the cold-rolled material to bend the cold-rolled material 3. By performing such a repeating bending process, compared with conventional cold rolling, the deformation form of the material can be changed. Therefore, the strain state (distribution, density, etc.) and crystal orientation in the structure after the bending process can be made different from those obtained by conventional cold rolling. As a result, the orientation density of the α-fiber in at least the plate surface of the copper alloy sheet can be reduced. In contrast, in the conventionally cold-rolled material, when recrystallization is carried out by a melting treatment step or the like, a recrystallized texture is formed based on the strain of cold rolling or the rolling texture, so it is difficult to reduce the orientation density of the α-fiber. In this regard, the recrystallized texture obtained by heat-treating the cold-rolled material after the repeating bending process step [Step 6] can control the α-fiber within a specified range.

[0090] In this repeating bending process step [Step 6], the following cycle is repeated within a range of 4 or more and 10 or less times: a bending deformation in which the ratio of the bending radius of the cold-rolled material to the plate thickness (bending radius / plate thickness ratio) is in the range of 8.0 or more and 10.0 or less, and a process of restoring this bending deformation.

[0091] Here, when the ratio of the bending radius of the cold-rolled material to the plate thickness is less than 8.0, cracks are likely to occur on the surface of the cold-rolled material. On the other hand, when the ratio of the bending radius of the cold-rolled material to the plate thickness is greater than 10.0, or when the number of times of repeating the bending process is less than 4 times, the amount of strain caused by the repeating bending process step [Step 6] becomes small, so that the orientation density of the α-fiber becomes too large, and thus the drawability of the copper alloy sheet decreases. In particular, the ratio of the bending radius of the cold-rolled material to the plate thickness is preferably in the range of 8.0 or more and 9.0 or less. In addition, the bending process in the repeating bending process step [Step 6] can be repeated 10 times or more, but since work hardening saturates, the effect of processing beyond that becomes small. Therefore, from the viewpoint of productivity, repeating 10 times or more is not ideal.

[0092] In particular, when using a processing machine 1 that presses the work rolls 2 alternately from both plate surface sides of the cold-rolled material as shown in Figure 1 , the bending radius during the bending process can be approximated to the radius of the work roll 2. In addition, Figure 1 shows an example of a processing machine 1 that performs a cycle of 7 bending deformations and restoring the bending deformation.

[0093] (vii) Melting treatment step [Step 7]

[0094] The melting treatment step [Step 7] is a step of performing heat treatment on the cold-rolled material after the repeated bending process [Step 6] to recrystallize it and then cooling it. Here, the conditions of the heat treatment in the melting treatment step [Step 7] can, for example, set the reaching temperature in the range of 700 °C or higher and 1000 °C or lower, and can set the holding time at the reaching temperature in the range of 10 seconds or longer and 60 seconds or shorter. Here, when the reaching temperature is lower than 700 °C or when the holding time is less than 10 seconds, the precipitation strengthening amount in the following aging heat treatment step [Step 8] decreases, resulting in a decrease in the tensile strength of the copper alloy sheet. On the other hand, when the reaching temperature exceeds 1000 °C or when the holding time exceeds 60 seconds, the crystal grain size becomes coarser, resulting in a tendency for the tensile strength of the copper alloy sheet to decrease. Therefore, from the viewpoint of improving the tensile strength of the copper alloy sheet, it is preferable to set the reaching temperature to 950 °C or lower.

[0095] The melted material after the melting treatment step [Step 7] is preferably cooled immediately. More specifically, the cooling of the melted material after the melting treatment step [Step 7] is preferably carried out at a cooling rate of 40 °C / s or more. Here, when the cooling rate is lower than 40 °C / s, coarse precipitates are generated during the cooling process, resulting in a decrease in the precipitation strengthening amount in the aging heat treatment step [Step 8], and thus a tendency for the tensile strength of the copper alloy sheet to decrease.

[0096] (viii) Aging heat treatment step [Step 8]

[0097] The aging heat treatment step [Step 8] is a step of performing heat treatment on the cooled melted material to perform precipitation strengthening. Here, the conditions of the heat treatment in the aging heat treatment step [Step 8] are that the reaching temperature is in the range of 400 °C or higher and 600 °C or lower, and the holding time at the reaching temperature is in the range of 1 hour or longer and 10 hours or shorter. Here, when the reaching temperature is lower than 400 °C or when the holding time is less than 1 hour, it becomes difficult to obtain precipitation strengthening, resulting in a tendency for the tensile strength and conductivity of the copper alloy sheet to easily decrease. On the other hand, when the reaching temperature exceeds 600 °C or when the holding time exceeds 10 hours, the precipitates become coarser, resulting in a tendency for the tensile strength of the copper alloy sheet to easily decrease.

[0098] (ix) Second cold rolling step [Step 9]

[0099] The second cold rolling step [Step 9] is a step of further cold rolling the cold-rolled material after the aging heat treatment step [Step 8]. Here, the total processing rate in the second cold rolling step [Step 9] is preferably in the range of 5% or more and 50% or less, and more preferably in the range of 5% or more and 40% or less. Here, when the total processing rate is less than 5%, the amount of work hardening becomes small, so the tensile strength of the copper alloy sheet tends to decrease. In addition, when the total processing rate is greater than 50%, the drawability of the copper alloy sheet decreases. In particular, from the viewpoint of further improving the tensile strength of the copper alloy sheet and further improving the drawability of the copper alloy sheet, the total processing rate in the second cold rolling step [Step 9] is preferably set to 40% or less. This second cold rolling step [Step 9] can be carried out according to the desired tensile strength.

[0100] When used in applications such as the hold-down of a connector, where a part with a spring mechanism is combined in a structure obtained by deep drawing, and the depth of deep drawing is relatively shallow, less than 5 mm, and the tensile strength is prioritized over the drawability, the second cold rolling step [Step 9] is preferably carried out at a relatively high processing rate of 20% or more, whereby the tensile strength of the copper alloy sheet can be improved. On the other hand, when used in applications such as camera module cases, shielding cases, vibration device housings, and battery housings, where the depth of deep drawing is relatively deep, 5 mm or more, and the drawability is prioritized over the tensile strength, the second cold rolling step [Step 9] is preferably carried out at a low processing rate of 20% or less.

[0101] (x) Low-temperature annealing step [Step 10]

[0102] The low-temperature annealing step [Step 10] is an annealing step of heat-treating the cold-rolled material after the second cold rolling step [Step 9]. The conditions for the heat treatment in this low-temperature annealing step [Step 10] are preferably: the reaching temperature is in the range of 300 °C or more and 500 °C or less, and the holding time at the reaching temperature is in the range of 10 seconds or more and 30 minutes or less. Here, when the reaching temperature is lower than 300 °C or when the holding time is less than 10 seconds, the strain remaining in the annealed cold-rolled material is excessive, so the drawability of the copper alloy sheet decreases. On the other hand, when the reaching temperature exceeds 500 °C or when the holding time at the reaching temperature exceeds 30 minutes, the work hardening caused by cold rolling disappears.

[0103] In addition, the heating and cooling rates before and after the annealing in the low-temperature annealing step [Step 10] are not particularly limited, and can be set, for example, in the range of 1 °C / s or more and 100 °C / s or less.

[0104] [7] Uses of the copper alloy sheet

[0105] The copper alloy sheet of the present invention is preferably a copper alloy sheet for deep drawing. That is, the copper alloy sheet of the present invention is particularly suitable for performing deep drawing to obtain a deep-drawn part, for example, suitable for forming parts for electronic devices and electronic components, parts for automotive on-vehicle use, etc. More specifically, it is particularly suitable for connectors, lead frames, relays, switches, sockets, shielding cases, shielding cans, camera module cases, vibration device housings, heat dissipation parts for liquid crystal and organic EL displays, connectors for batteries and automotive on-vehicle use, shielding cases, shielding cans, etc., which require support for miniaturization and high current.

[0106] The embodiments of the present invention have been described above, but the present invention is not limited to the above embodiments, and various changes can be made within the scope of the present invention, including all aspects included in the concept of the present invention and the scope of the patent application.

[0107] [Examples]

[0108] Next, in order to make the effects of the present invention more clear, examples and comparative examples of the present invention will be described, but the present invention is not limited to these examples of the present invention.

[0109] (Examples 1 to 18 and Comparative Examples 1 to 17 of the Present Invention)

[0110] The following melting and casting step [Step 1] was carried out to obtain an ingot: various copper alloy materials having the alloy compositions shown in Table 1 were melted, cooled in an atmospheric environment, and cast. After performing a reheating step [Step 2] on this ingot, a hot rolling step [Step 3] was immediately carried out to obtain a hot-rolled material. The reheating step [Step 2] was carried out with a reaching temperature (heat treatment temperature) of 1000 °C and a holding time (heat treatment time) at the reaching temperature of 1 hour. The hot rolling step [Step 3] was carried out in a temperature range of 700 °C or higher and 1000 °C or lower and in a manner such that the total processing rate was 50% or more with the long side direction of the ingot as the rolling direction. Then, it was cooled to room temperature by water cooling.

[0111] For the cooled hot-rolled material, surface cutting was performed to shave off about 1 mm to 2 mm from both the front and back surfaces to remove the surface oxide film, and then the following first cold rolling step [Step 4] was carried out: rolling was carried out in a manner such that the total processing rate was 98.0% with the long side direction of the hot-rolled material as the rolling direction.

[0112] An intermediate annealing step [Step 5] was carried out, and then a repeated bending process step [Step 6] was carried out. The intermediate annealing step [Step 5] was carried out on the rolled material after performing the first cold rolling step [Step 4] with the reaching temperature and holding time described in Table 2. The repeated bending process step [Step 6] was carried out usingFigure 1 The processing machine 1 described, and under the conditions of the ratio of the bending radius of the cold-rolled material to the plate thickness and the number of bending-back times [times] described in Table 2, repetitive bending-back processing is performed on the cold-rolled material.

[0113] A melting treatment step [Step 7] is performed, and it is cooled to room temperature at a cooling rate of 100 °C / s. The melting treatment step [Step 7] is heat treatment of the cold-rolled material after the repetitive bending-back processing step [Step 6] at the arrival temperature and holding time described in Table 2.

[0114] An aging heat treatment step [Step 8] is performed. Next, a second cold rolling step [Step 9] is performed. The aging heat treatment step [Step 8] is heat treatment of the melted and treated material after cooling at the arrival temperature and holding time described in Table 2. The second cold rolling step [Step 9] is rolling in such a way that the long side direction becomes the rolling direction under the condition of the total processing rate described in Table 2.

[0115] A low-temperature annealing step [Step 10] is performed to produce the copper alloy sheet of the present invention. The low-temperature annealing step [Step 10] is heat treatment of the rolled material after the second cold rolling step [Step 9] at the arrival temperature and holding time described in Table 2.

[0116] On the other hand, regarding Comparative Example 15, a copper alloy sheet is produced without performing the repetitive bending-back processing step [Step 6]. In addition, regarding Comparative Example 16, a copper alloy sheet is produced in the same manner as the copper alloy sheet of Patent Document 1 without performing the intermediate annealing step [Step 5] and the repetitive bending-back processing step [Step 6]. In addition, regarding Comparative Example 17, a copper alloy sheet is produced in the same manner as the copper alloy sheet of Patent Document 2 without performing the repetitive bending-back processing step [Step 6] and the aging heat treatment step [Step 8].

[0117] In addition, in Table 1, among the constituent components other than copper (Cu), nickel (Ni), and silicon (Si), tin (Sn), zinc (Zn), magnesium (Mg), iron (Fe), and chromium (Cr) are set as optional addition components and are described separately from other components. In addition, in Table 1, a horizontal line “-” is described in the column of the component not contained in the alloy composition of the copper alloy material, making the fact that the component is not contained or even if contained is below the detection limit value clearer.

[0118] [Various measurement and evaluation methods]

[0119] Using the copper alloy sheets of the above-described present invention examples and comparative examples, the following-described characteristic evaluations are performed. The evaluation conditions for each characteristic are as follows.

[0120] [1] Average value of the orientation density of the α-fiber of the copper alloy sheet

[0121] The average value of the orientation density of the α-fiber in the copper alloy sheet was obtained from the crystal orientation analysis data calculated using analysis software (OIM Analysis manufactured by TSL Corporation) from the crystal orientation data continuously measured by the EBSD detector attached to a high-resolution scanning analytical electron microscope (JSM-7001FA manufactured by JEOL Ltd.) for the copper alloy sheets obtained in the examples and comparative examples of the present invention. The measurement was carried out by electrolytic polishing the surface (sheet surface) of the copper alloy sheet and at a step size of 0.5 μm in a field of view of about 400 μm × 800 μm in the electrolytically polished surface.

[0122] When obtaining the crystal orientation distribution function (ODF) represented by Euler angles (φ1, φ, φ2) as crystal orientation analysis data by setting the measurement points with a reliability index CI value of 0.1 or more among the crystal orientation data obtained by the EBSD method in this way as the objects of analysis, for the orientation of the α-fiber in the range of φ1 from 0 to 35°, the average value of the ODF intensity based on a randomly oriented sample (reference value = 1) was obtained as the average value of the orientation density of the α-fiber. In addition, in this example, the average value of the orientation density of the α-fiber being 3.0 or less was set as the qualified grade. The results are shown in Table 3.

[0123] [2] Area ratio of the region having crystal planes with an angle of 10° or less between the normal direction (ND) of the sheet surface and the normal direction of the (100) plane

[0124] The area ratio of the region having crystal planes with an angle of 10° or less between the normal direction (ND) of the sheet surface and the normal direction of the (100) plane in the copper alloy sheet was obtained by the following method: Setting the measurement points with a reliability index CI value of 0.1 or more among the crystal orientation data obtained by the EBSD method as the objects of analysis, and calculating the ratio of the area of the region of crystal planes (atomic planes) with an angle of 10° or less between the normal of the (100) plane and the normal direction (ND) of the sheet surface to the area of the measurement region. The results are shown in Table 3.

[0125] [3] Measurement of the tensile strength of the copper alloy sheet

[0126] The measurement of the tensile strength was carried out using two test pieces of No. 13B specified in JIS Z2241, and the average value of the tensile strength obtained from the two test pieces was set as the measured value. The test pieces were cut from the test material with the direction parallel to the rolling direction as the long side direction. In this example, the tensile strength in the range of 500 MPa or more and 900 MPa or less was set as the qualified grade. The results are shown in Table 3.

[0127] [4]Measurement of Electrical Conductivity of Copper Alloy Sheet

[0128] The electrical conductivity of the copper alloy sheet is measured twice using the four-terminal method, and the average value of the electrical conductivity obtained from the two measurements is set as the measured value of the electrical conductivity. In this example, a qualified grade is set when the electrical conductivity is 30% IACS or more. The results are shown in Table 3.

[0129] [5]Evaluation of Deep Drawing Processability of Copper Alloy Sheet

[0130] The deep drawing processability of the copper alloy sheet uses a blank with a diameter of 40 mm formed by stamping and blanking from a copper alloy sheet with a thickness of 0.2 mm, and lubricating oil (trade name: PRETON R-303P, manufactured by SUGIMURA Chemical Industry Co., Ltd.) is applied to its surface. Then, a die with a shoulder radius of curvature of 3 mm and a punch with a cylindrical shape at the front end with a diameter of 20 mm and a corner radius of curvature of 3 mm at the front end are used. The gap between the punch and the die is set to 0.27 mm, and the punch is pressed into the center of the blank. Thus, a cylindrical cup is formed by deep drawing. At this time, the reduction in the sheet thickness near the front end of the punch in the cup is evaluated. At this time, the anti-wrinkle pressure, which is the pressure applied to the copper alloy sheet as the material to be processed, is set to 1500 N.

[0131] Here, the sheet thickness near the front end of the punch is measured as follows: The cylindrical cup, which is a deep-drawn part, is embedded in resin, and mechanical grinding is performed to expose a cross-section 10 along the rolling direction of the bottom surface including the central axis of the cylinder as shown in Figure 2 Then, the R part 11 near the front end of the punch in the cross-section 10 is observed with an optical microscope. At this time, a tangent line A at an angle of 45° to the bottom surface 12 of the deep-drawn part is drawn in a tangential manner to the R part 11, and a perpendicular line B passing through the vertex of this tangent line A and the R part 11 and perpendicular to the tangent line A is drawn. The length of the perpendicular line B, which is a line segment spanning the cross-section 10, is set as the sheet thickness t1 near the front end of the punch.

[0132] Using this sheet thickness t1 and the sheet thickness t0 of the copper alloy sheet before deep drawing, the reduction rate [%] of the sheet thickness near the front end of the punch is calculated according to the following formula (1).

[0133] Reduction rate of sheet thickness [%] = ((t0 - t1) / t0) × 100...(1)

[0134] In addition, for the results of the calculated reduction rate of the sheet thickness, evaluation is performed according to the following evaluation criteria. The results are shown in Table 3.

[0135] <Evaluation Criteria for Reduction Rate of Sheet Thickness near Front End of Punch>

[0136] "4" (excellent): When the reduction rate of the sheet thickness is 2% or less

[0137] “3” (Good): When the reduction rate of the sheet thickness exceeds 2% and is 4% or less

[0138] “2” (Acceptable): When the reduction rate of the sheet thickness exceeds 4% and is 6% or less

[0139] “1” (Unacceptable): When the reduction rate of the sheet thickness exceeds 6%, and when the blank fractures during the drawing process

[0140] [Table 1]

[0141]

[0142] [Table 2]

[0143]

[0144] [Table 3]

[0145]

[0146] Based on the results of Tables 1 to 3, the alloy compositions of the copper alloy sheets of Invention Examples 1 to 18 are within the appropriate range of the present invention. At the same time, the average value of the orientation density of the α fibers is 3.0 or less, the tensile strength is in the range of 500 MPa or more and 900 MPa or less, and the conductivity is 30% IACS or more. At this time, the evaluation of the draw formability is easily evaluated as “2”, “3” or “4”.

[0147] Therefore, the copper alloy sheets of Invention Examples 1 to 18 can have high tensile strength and high conductivity, and excellent draw formability can be obtained.

[0148] In particular, for the copper alloy sheets of Invention Examples 2 to 18, since the temperature reached in the intermediate annealing step [Step 5] is 700 °C or more, the area of the crystal plane with a smaller angle between the normal direction (ND) of the sheet surface and the normal direction of the (100) plane is reduced. Accordingly, particularly for Invention Examples 2 to 8, 10 to 18, a higher evaluation of draw formability than that of Invention Example 1 is obtained.

[0149] In addition, when comparing the copper alloy sheets of Invention Examples 2, 4, and 5, the ratio of the bending radius of the cold-rolled material to the sheet thickness (bending radius / sheet thickness ratio) in the repeated bending process [Step 6] of the copper alloy sheets of Invention Examples 4 and 5 is 9 or less and smaller than that of Invention Example 2. Thus, it is considered that a large amount of bending strain is introduced, and accordingly, the average value of the orientation density of the α fibers in the sheet surface of the copper alloy sheet becomes smaller. Thereby, a higher evaluation of draw formability than that of Invention Example 2 is obtained.

[0150] In addition, for the copper alloy sheets of Examples 5 to 7, 11, and 17 of the present invention, the average value of the orientation density of the α fibers is 2.3 or less, and the tensile strength is in the range of 780 MPa or more and 900 MPa or less. At this time, the reduction rate of the sheet thickness near the tip of the punch is less than 2.0%, and further excellent deep drawability is obtained.

[0151] In addition, when comparing the copper alloy sheets of Examples 5 and 7 of the present invention, the reaching temperature of the copper alloy sheet of Example 5 in the melting treatment step [Step 7] is 800 °C, which is lower than that of Example 7. Therefore, it is considered that grain coarsening is less likely to occur, and thus a higher tensile strength than that of Example 7 is obtained.

[0152] In addition, when comparing the copper alloy sheets of Examples 5 and 8 of the present invention, the reaching temperature of the copper alloy sheet of Example 5 in the aging heat treatment step [Step 8] is 480 °C, which is lower than that of Example 8. Therefore, it is considered that coarsening of the precipitates is less likely to occur, and thus a higher tensile strength than that of Example 8 is obtained.

[0153] In addition, when comparing the copper alloy sheets of Examples 4 and 9 of the present invention, the total processing rate of the copper alloy sheet of Example 4 in the second cold rolling step [Step 9] is 5%, which is lower than that of Example 9. Thereby, a lower tensile strength than that of Example 9 is obtained. In addition, since the total processing rate in the second cold rolling step [Step 9] is lower than that of Example 9, the average value of the orientation density of the α fibers in the sheet surface of the copper alloy sheet becomes smaller, and thereby, a higher evaluation of deep drawability than that of Example 9 is obtained.

[0154] In addition, when comparing the copper alloy sheets of Examples 4 and 10 of the present invention, the reaching temperature of the copper alloy sheet of Example 4 in the low-temperature annealing step [Step 10] is 500 °C, which is higher than that of Example 10. Thereby, a lower tensile strength than that of Example 10 is obtained. In addition, since the reaching temperature in the low-temperature annealing step [Step 10] is higher than that of Example 10, a value of the reduction rate of the sheet thickness near the tip of the punch smaller than that of Example 10 is obtained.

[0155] In addition, for the copper alloy sheet of Example 11 of the present invention, since the addition amounts of Ni (nickel) and Si (silicon) are less than those of Examples 1 to 10, 12 to 18, a higher conductivity than that of Examples 1 to 10, 12 to 18 is obtained. In addition, for the copper alloy sheets of Examples 1 to 15, 17, and 18 of the present invention, since the addition amounts of Ni (nickel) and Si (silicon) are less than those of Example 16, a higher conductivity than that of Example 16 is obtained.

[0156] In addition, the copper alloy sheets of Examples 1 to 17 of the present invention contain at least one optional additive component selected from the group consisting of Sn, Zn, Mg, Fe, and Cr in a total amount in the range of 0.10% by mass or more and 1.00% by mass or less, and have high tensile strength and high conductivity in the same manner as Example 18 of the present invention that does not contain any optional additive component, and a high evaluation of drawability is obtained.

[0157] Furthermore, the copper alloy sheets of the examples of the present invention are suitable for forming parts for electronic devices, electronic components, in-vehicle parts for automobiles, etc. In particular, the copper alloy sheets of Examples 8 and 16 having relatively high tensile strength are considered suitable for uses such as the compression part of a connector that incorporate a spring mechanism in the drawn shape, and can be selected according to the required characteristics of conductivity and drawability. In addition, the copper alloy sheets of Examples 4, 5, 6, 7, 8, and 10 having relatively high drawability are suitable for uses such as shield cases, camera module cases, vibration device housings, and vibration device housings. Among them, since the battery case generates heat, the copper alloy sheet of Example 11 having a relatively high thermal conductivity in proportion to the conductivity is considered particularly suitable from the viewpoint of heat dissipation countermeasures.

[0158] On the other hand, in the copper alloy sheets of Comparative Examples 1 to 17, since at least any one of the alloy composition, tensile strength, conductivity, and the average value of the orientation density of α-fibers in the plate surface is outside the appropriate range of the present invention, the tensile strength or conductivity does not reach the qualified grade, or the comprehensive evaluation of drawability is evaluated as "1".

[0159] In particular, the copper alloy sheet of Comparative Example 1 has a relatively high reaching temperature in the intermediate annealing step [Step 5], and thus, the area of crystal planes having an angle of 10° or less between the normal direction (ND) of the plate surface and the normal direction of the (100) plane increases. Therefore, the comprehensive evaluation of the drawability of the copper alloy sheet of Comparative Example 1 is evaluated as "1".

[0160] In addition, in the copper alloy sheet of Comparative Example 2, the ratio of the bending radius of the cold-rolled material to the plate thickness (bending radius / plate thickness ratio) in the repeated bending process [Step 6] is relatively large, so it is considered that sufficient bending strain is not introduced. As a result, the average value of the orientation density of α-fibers exceeds 3.0, and the comprehensive evaluation of drawability is evaluated as "1".

[0161] In addition, in the copper alloy sheet of Comparative Example 3, it is considered that the number of times of repeated bending in the repeated bending process [Step 6] is insufficient, and sufficient bending strain is not introduced. As a result, the average value of the orientation density of α-fibers exceeds 3.0, and the comprehensive evaluation of drawability is evaluated as "1".

[0162] In addition, the arrival temperature of the copper alloy sheet of Comparative Example 4 in the melting treatment step [Step 7] was high, and the tensile strength did not reach the qualified grade. This is considered to be because the arrival temperature in the melting treatment step [Step 7] was too high, resulting in grain coarsening.

[0163] In addition, the arrival temperature of the copper alloy sheet of Comparative Example 5 in the aging heat treatment step [Step 8] was high, and the tensile strength did not reach the qualified grade. This is considered to be because the arrival temperature in the aging heat treatment step [Step 8] was high, resulting in coarsening of the precipitates.

[0164] In addition, the arrival temperature of the copper alloy sheet of Comparative Example 6 in the aging heat treatment step [Step 8] was low, and the tensile strength did not reach the qualified grade. This is considered to be because the arrival temperature in the aging heat treatment step [Step 8] was too low, resulting in insufficient precipitation.

[0165] In addition, the total processing rate of the copper alloy sheet of Comparative Example 7 in the second cold rolling step [Step 9] was low, and the tensile strength did not reach the qualified grade. This is considered to be because the total processing rate in the second cold rolling step [Step 9] was too low, resulting in insufficient work hardening.

[0166] In addition, the total processing rate of the copper alloy sheet of Comparative Example 8 in the second cold rolling step [Step 9] was high, and the blank fractured during deep drawing. This is considered to be because the total processing rate in the second cold rolling step [Step 9] was too high, resulting in a decrease in the ductility of the copper alloy sheet.

[0167] In addition, the arrival temperature of the copper alloy sheet of Comparative Example 9 in the low-temperature annealing step [Step 10] was low, resulting in a tensile strength higher than the qualified grade and the blank fracturing during deep drawing. This is considered to be because the arrival temperature in the low-temperature annealing step [Step 10] was low, resulting in insufficient property adjustment of the copper alloy sheet.

[0168] In addition, the copper alloy sheet of Comparative Example 10 is an example where the conductivity did not reach the qualified grade.

[0169] In addition, the content of Si (silicon) in the alloy composition of the copper alloy sheet of Comparative Example 11 was more than the scope of the present invention, and the conductivity did not reach the qualified grade.

[0170] In addition, the content of Ni (nickel) in the alloy composition of the copper alloy sheet of Comparative Example 12 was more than the scope of the present invention, and the conductivity did not reach the qualified grade.

[0171] In addition, the content of Si (silicon) in the alloy composition of the copper alloy sheet of Comparative Example 13 was less than the scope of the present invention, and the tensile strength did not reach the qualified grade.

[0172] In addition, the content of Ni (nickel) in the alloy composition of the copper alloy sheet of Comparative Example 14 is less than the scope of the present invention, and the tensile strength fails to reach the qualified grade.

[0173] In addition, since the copper alloy sheet of Comparative Example 15 did not perform the repeated bending process step [Step 6], the average value of the orientation density of the α fibers exceeded 3.0, and the comprehensive evaluation of the drawing processability was evaluated as "1".

[0174] In addition, the copper alloy sheet of Comparative Example 16 was prepared according to Patent Document 1, and did not perform the intermediate annealing step [Step 5] and the repeated bending process step [Step 6]. The average value of the orientation density of the α fibers exceeded 3.0, and the comprehensive evaluation of the drawing processability was evaluated as "1". In addition, the alloy composition of the copper alloy sheet of Comparative Example 16 is different from that of the copper alloy sheet of the present invention.

[0175] In addition, the copper alloy sheet of Comparative Example 17 was prepared according to Patent Document 2, and did not perform the repeated bending process step [Step 6]. The average value of the orientation density of the α fibers exceeded 3.0, and the comprehensive evaluation of the drawing processability was evaluated as "1". In addition, the copper alloy sheet of Comparative Example 17 did not perform the aging heat treatment step [Step 8] either, and the conductivity did not reach the qualified grade. In addition, the alloy composition of the copper alloy sheet of Comparative Example 17 is different from that of the copper alloy sheet of the present invention.

[0176] 1: Processing machine

[0177] 2: Working roll

[0178] 3: Cold-rolled material

[0179] 10: Cross-section of drawn part

[0180] 11: R part

[0181] 12: Bottom surface of drawn part

[0182] A: Tangent line at an angle of 45° to the bottom surface of the drawn part

[0183] B: Perpendicular line passing through the tangent line A and the vertex of the R part and perpendicular to the tangent line A.

Claims

1. A copper alloy sheet having the following alloy composition: containing Ni in the range of 1.00% by mass or more and 5.00% by mass or less, Si in the range of 0.20% by mass or more and 1.30% by mass or less, and the balance being composed of Cu and unavoidable impurities; wherein, the average value of the orientation density of the α-fiber in at least the sheet surface of the copper alloy sheet obtained by crystal orientation analysis according to the EBSD method is 3.0 or less, the tensile strength is in the range of 500 MPa or more and 900 MPa or less, and the conductivity is 30% IACS or more.

2. The copper alloy sheet according to claim 1, wherein, Regarding the aggregation of crystal planes facing the normal direction (ND) of the sheet surface obtained by the aforementioned crystal orientation analysis, the ratio of the area of the region having crystal planes with an angle of 10° or less between the normal direction (ND) and the normal direction of the (100) plane to the area of the measurement region of the sheet surface is 10% or less.

3. The copper alloy sheet according to claim 1, wherein, The aforementioned alloy composition further contains at least one optional additive component selected from the group consisting of Sn, Zn, Mg, Fe, and Cr in a total amount in the range of 0.10% by mass or more and 1.00% by mass or less.

4. A copper alloy sheet for drawing work, which is composed of the copper alloy sheet according to any one of claims 1 to 3.

5. A drawn part obtained by drawing the copper alloy sheet according to any one of claims 1 to 3.

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