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, can obtain excellent drawability, and especially can reduce the size of a lug part formed at the edge of the drawn article. 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 remainder being Cu and unavoidable impurities. The copper alloy sheet has a maximum value of strength of 3.0 or less in an inverse pole diagram with respect to a crystal plane facing a normal direction (ND) of a plate surface as measured on the plate surface of the copper alloy sheet as obtained by crystal orientation analysis by an EBSD method, a tensile strength in the range of 500 MPa to 900 MPa, and an electrical conductivity of 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, for 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, batteries, probe pins, and gas shut-off valves for electronic devices or in-vehicle use in automobiles, and are often subjected to stamping processes such as blanking, bending, deep drawing, and bulging.

[0003] As a copper alloy for such stamping processes, for example, Patent Document 1 discloses a copper alloy containing, by mass%, Ni: 1.0 to 3.6%, Si: 0.2 to 1.0%, Sn: 0.05 to 3.0%, Zn: 0.05 to 3.0%, with the balance being composed of copper and unavoidable impurities, and discloses a copper alloy having the following microstructure: an average crystal grain size of 25 μm or less, and in the measurement results obtained by the SEM-EBSP method, the average area ratio of the cube (Cube) orientation {001}<100> is 20 to 60%, and the average total area ratio of three orientations of the brass (Brass) orientation {011}<211>, the S orientation {123}<634>, and the copper (Copper) orientation {112}<111> is 20 to 50%; and the KAM value is 1.00 to 3.00. In Patent Document 1, by respectively controlling the area ratio of the cube orientation {001}<100>, the average total area ratio of the three orientations of the brass orientation {011}<211>, the S orientation {123}<634>, and the copper orientation {112}<111>, and the KAM value, a copper alloy with less strength anisotropy and excellent bendability can be obtained.

[0004] In addition, Patent Document 2 discloses a Cu-Ni-Si-based copper alloy sheet excellent in deep drawability and fatigue resistance, which contains 1.0 to 3.0% by mass of Ni and contains Si at a concentration of 1 / 6 to 1 / 4 of the mass% concentration relative to Ni, with the balance being composed of Cu and unavoidable impurities, the Goss orientation density measured by the EBSD method using a scanning electron microscope equipped with a backscattered electron diffraction imaging system is 2.0 to 6.0%, the average value of KAM is 0.9 to 1.5°, and the ratio (Lσ / L) of the total special grain boundary length Lσ of special grain boundaries to the total grain boundary length L of grain boundaries is 60 to 70%. In Patent Document 2, by controlling the Goss orientation density, the KAM value, and the total special grain boundary length of the Cu-Ni-Si alloy sheet, the fatigue characteristics and deep drawability of the copper alloy sheet can be improved.

[0005] [Prior Art Documents]

[0006] (Patent Documents)

[0007] Patent Document 1: Japanese Patent Application Laid-Open No. 2011-162848

[0008] Patent Document 2: Japanese Patent Application Laid-Open No. 2012-122114 Summary of the Invention

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

[0010] In recent years, with the high performance, high current, and miniaturization of electronic devices and in-vehicle devices for automobiles, there has been an increasing demand for higher mechanical properties and electrical conductivity (or thermal conductivity) in stamping products, which are one of the components thereof. In particular, there is a need for a copper alloy sheet composed of a material that can exhibit both higher mechanical properties and electrical conductivity (or thermal conductivity) than brass and nickel silver, which have been conventionally used in deep-drawn parts for electronic devices and in-vehicle devices for automobiles, such as 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 (electroluminescence) displays, batteries, probe pins, gas shut-off valves, etc.

[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 metal sheet to form various shaped bottomed containers such as cylinders, square cylinders, and cones. In addition, the so-called "deep-drawn part" refers to 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, crushing, twisting, etc.) in combination with deep drawing.

[0012] If the depth of this deep drawing is increased, the material becomes prone to fracture, so the processing often becomes difficult. At this time, even if the processing can be carried out without fracture, large undulations (ears) are likely to be formed at the edge of the obtained deep-drawn part. In particular, in deep drawing where the depth of the deep-drawn part is relatively large with respect to the diameter of the punch during processing, multi-stage deep drawing is required for forming, so the ears are particularly likely to become large. Here, if large ears are formed, not only will the shape of the deep-drawn part be impaired, but also adjacent ears will overlap during the deep drawing process, or cracks are likely to form between adjacent ears. In addition, if large ears are formed, an additional step for removing the ears from the deep-drawn part is required, so there is a need for a copper alloy sheet that can reduce the ears formed at the edge of the deep-drawn part.

[0013] In this regard, the Cu-Ni-Si alloy described in Patent Document 1 reduces the difference in mechanical properties between the direction parallel to the rolling direction (rolling parallel direction) and the direction perpendicular to the rolling direction (rolling perpendicular direction) by aggregating cubic orientations. Therefore, in applications such as connectors, terminals, switches, relays, and lead frames where bending is performed with the rolling parallel direction and the rolling perpendicular direction as the bending axes, anisotropy can be reduced by considering only these two directions. However, deep drawing affected by anisotropy in the rolling parallel direction, the rolling perpendicular direction, and all directions has not been explored at all, and moreover, reduction of ears formed at the edge of a drawn part, and having both high tensile strength and high conductivity have not been disclosed, nor have the evaluation results of these characteristics been shown. In this regard, since the Cu-Ni-Si alloy of Patent Document 1 aggregates cubic orientations, the mechanical properties in the direction at a 45° angle relative to the rolling direction are significantly different from those in the rolling parallel direction and the rolling perpendicular direction. Therefore, when this copper alloy is used for deep drawing, relatively large ears are formed at the edge of the obtained drawn part. Further, even when examining the manufacturing method, the Cu-Ni-Si alloy described in Patent Document 1 is obtained by sequentially performing a casting step, a surface cutting step of an ingot, a soaking step, a hot rolling step, a cold rolling step, a melting treatment step (recrystallization annealing step), an age hardening step, a cold rolling step, and a low-temperature annealing step, and does not perform an intermediate annealing step for coarsening crystal grain size after the hot rolling step.

[0014] In addition, although Patent Document 2 describes an improvement in the deep drawability (deep drawing processability) of a copper alloy sheet, regarding the evaluation of deep drawability, only the presence or absence of fracture when a punch with a relatively large spherical tip having a diameter of 10 mm is pressed against a blank material taken from the copper alloy sheet to form a cup is evaluated, and only the presence or absence of fracture under loose deep drawing conditions is evaluated. The evaluation results under deep drawing conditions where the depth of the drawn part during processing is relatively large with respect to the diameter of the punch are not shown. In addition, the ears formed at the edge of the drawn part are not explored at all in Patent Document 2. Moreover, reduction of ears formed at the edge of a drawn part, and having both high tensile strength and high conductivity have not been disclosed, nor have the evaluation results of these characteristics been shown. Further, even when examining the manufacturing method, the copper alloy sheet described in Patent Document 2 is obtained by sequentially performing a hot rolling step, a cold rolling step, a melting treatment step, an aging treatment step, a pickling treatment step, a final cold rolling step, and a low-temperature annealing step, and at least does not perform an intermediate annealing step for coarsening crystal grain size after the hot rolling step.

[0015] Accordingly, the present invention has been made in view of the above problems, and an object thereof is to provide a copper alloy sheet, a copper alloy sheet for deep drawing, and a deep drawn part, which have high tensile strength and high electrical conductivity, and can obtain excellent deep drawability, and in particular, can reduce the ears formed at the edges of the deep drawn part.

[0016] [Technical means for solving the problem]

[0017] The present inventors have found 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 maximum value of the intensity of the inverse pole figure of the crystal plane with respect to the normal direction (ND) of the plate surface of the copper alloy sheet obtained by crystal orientation analysis according to the 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 deep drawability can be improved. In particular, the ears formed at the edges of the deep drawn part can be reduced, and thus the present invention has been completed.

[0018] (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 maximum value of the intensity of the inverse pole figure of the crystal plane with respect to the normal direction (ND) of the plate surface of the copper alloy sheet measured on the plate surface and 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 electrical conductivity is 30% IACS or more.

[0019] (2) The copper alloy sheet according to the above (1), wherein the proportion of the orientation angle at which the intensity in the inverse pole figure becomes 2.0 or less in all the orientation angles is 50% or more.

[0020] (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.

[0021] (4) A copper alloy sheet for deep drawing, which is composed of the copper alloy sheet according to any one of the above (1) to (3).

[0022] (5) A drawn part is obtained by drawing the copper alloy sheet according to any one of the above (1) to (3).

[0023] [Advantages of the Invention]

[0024] 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, and in particular, can reduce the ears formed at the edge of the drawn part. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a diagram for explaining a method of measuring the size of the ears (undulations) formed at the edge of a drawn part of a general copper alloy sheet. Figure 1 (a) is a bottom view of the drawn part when a line segment extending radially from the center position of the bottom surface of the drawn part to the circular contour line of the bottom surface is drawn every 45° of rotation. Figure 1 (b) is Figure 1 A perspective view of the drawn part of (a), showing the height from the bottom surface position of the drawn part to the ears existing at the upper edge. DETAILED DESCRIPTION OF THE INVENTION

[0026] Next, embodiments of the present invention will be described. The following description is merely an example of the embodiments in the present invention and is not intended to limit the scope of the patent application.

[0027] The copper alloy sheet according to the present invention is 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; the maximum value of the intensity of the inverse pole figure of the crystal plane with respect to the normal direction (ND) of the plate surface measured on 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.

[0028] The copper alloy sheet of the present invention suppresses the development of the aggregate structure by containing appropriate amounts of Ni and Si respectively and manufacturing under appropriate manufacturing conditions, so that the maximum value of the intensity of the inverse pole figure is reduced to 3.0 or less, thereby reducing anisotropy. As a result, the ears formed at the edge of the drawn part, that is, the undulations at the edge of the drawn part, can be reduced. 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, especially can reduce the ears formed at the edge of the drawn part.

[0029] [1] Alloy composition of copper alloy sheet

[0030] 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, and Si in the range of 0.20% by mass or more and 1.30% by mass or less are contained as essential components.

[0031] Hereinafter, the reasons for limiting the alloy composition of the copper alloy sheet will be described.

[0032] (Ni: 1.00% by mass or more and 5.00% by mass or less)

[0033] Ni (nickel) is an important component that has the effect of improving the tensile strength of the copper alloy sheet, and Ni is contained in the range of 1.00% by mass or more and 5.00% by mass or less. Here, when the Ni content is less than 1.00% by mass, a high tensile strength of 500 MPa or more cannot be obtained. In addition, if the Ni content is more than 5.00% by mass, the tensile strength of the copper alloy sheet exceeds 900 MPa, and it becomes easy to generate a coarse second phase composed of a compound with Si, and this second phase is likely to become a crack initiation point during drawing processing. In addition, if the Ni content is more than 5.00% by 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 drawn part less likely to crack, the Ni content is in the range of 1.00% by mass or more and 5.00% by mass or less, preferably in the range of 1.00% by mass or more and 4.50% by mass, more preferably in the range of 1.50% by mass or more and 4.50% by mass, and further more preferably in the range of 2.00% by mass or more and 4.00% by mass or less. In particular, from the viewpoint of further improving the tensile strength of the copper alloy sheet, the Ni content is preferably 1.50% by mass or more. In addition, from the viewpoint of further improving the conductivity of the copper alloy sheet, the Ni content is preferably 4.50% by mass or less.

[0034] (Si: 0.20 mass % or more and 1.30 mass % or less)

[0035] 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 %, a high tensile strength of 500 MPa or more cannot be obtained. In addition, if the Si content is more than 1.30 mass %, the tensile strength of the copper alloy sheet exceeds 900 MPa, and it becomes easy to form a coarse second phase composed of a compound with Ni. 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 decreases. 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 further improving the tensile strength of the copper alloy sheet, the Si content is preferably 0.30 mass % or more. In addition, from the viewpoint of further improving the conductivity of the copper alloy sheet, the Si content is preferably 1.10 mass % or less.

[0036] <Optional additive components>

[0037] 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.

[0038] (Sn: 0.10 mass % or more and 0.30 mass % or less)

[0039] 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.

[0040] (Zn: 0.10 mass % or more and 0.50 mass % or less)

[0041] 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.

[0042] (Mg: 0.10 mass% or more and 0.30 mass% or less)

[0043] Mg (magnesium) is a component that has the effect of improving the stress relaxation resistance 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.

[0044] (Fe: 0.05 mass% or more and 0.30 mass% or less)

[0045] Fe (iron) is a component that has the following effects: the effect of suppressing the coarsening of grains after dynamic recrystallization in the following hot rolling step [Step 3], and the effect of preventing the 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 point of cracks. Therefore, the Fe content is preferably in the range of 0.05 mass% or more and 0.30 mass% or less.

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

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

[0048] (Total content of optional additive components: 0.10 mass% or more and 1.00 mass% or less)

[0049] In order to obtain the effects obtained by the arbitrarily added components described above, these arbitrarily added components preferably contain a total of 0.10% by mass or more. On the other hand, if a large amount of these arbitrarily added components is included, the conductivity will decrease. Therefore, the total content of the arbitrarily added components is preferably set to 1.00% by mass or less.

[0050] (Remaining part: Cu and unavoidable impurities)

[0051] The copper alloy used to form the copper alloy sheet has the following alloy composition: In addition to the above components, the remaining part is composed of Cu (copper) and unavoidable impurities. In addition, the so-called "unavoidable impurities" referred to here means an impurity that is generally present in raw materials in metal products and is unavoidably mixed in during the manufacturing process and is originally unnecessary, but is tolerable because it is in trace amounts and does not affect the properties of the metal product. Examples of the components that can be listed 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, to 0.05% by mass for each of the above components, and the total amount of the above components is 0.20% by mass.

[0052] [2] Regarding the maximum value of the inverse pole figure intensity of the crystal plane in the normal direction (ND) of the sheet surface

[0053] The maximum value of the inverse pole figure intensity of the crystal plane in the normal direction (ND) of the sheet surface of the copper alloy sheet of the present invention, obtained by crystal orientation analysis according to the EBSD method, measured on the sheet surface of the copper alloy sheet, is 3.0 or less. If the maximum value of the inverse pole figure intensity exceeds 3.0, the orientation of any atomic plane (crystal plane) becomes higher, and the anisotropy becomes higher according to the oriented atomic plane. That is, from the viewpoint of improving the drawability of the copper alloy sheet, especially from the viewpoint of reducing the ears (undulations) formed at the edge of the drawn part, it is important to suppress the orientation of all atomic planes (crystal planes). At this time, in order to evaluate the orientation of the copper alloy sheet, it is effective to evaluate the maximum value in the inverse pole figure. Here, from the viewpoint of improving the drawability, the maximum value of the inverse pole figure intensity of the crystal plane in the normal direction (ND) of the sheet surface is preferably 2.6 or less, more preferably 2.5 or less, and further more preferably 2.0 or less. On the other hand, the lower limit of the maximum value of the inverse pole figure intensity is not particularly limited and can be 1.0 or 1.2.

[0054] Here, the maximum value of the intensity of the inverse pole figure can be obtained from the crystal orientation analysis data calculated using analysis software (OIM Analysis, manufactured by TSL Corporation) from the crystal orientation data continuously measured using the EBSD detector attached to a high-resolution scanning analytical electron microscope (JSM-7001FA, manufactured by JEOL Ltd.). In addition, "EBSD" refers to the abbreviation of Electron BackScatter Diffraction, which is a crystal orientation analysis technique using the reflection electron Kikuchi line diffraction (SEM) generated by irradiating an electron beam on a sample, i.e., a copper sheet, in a scanning electron microscope (SEM). "OIM Analysis" refers to the analysis software for the data measured by EBSD. The measurement can be performed on the surface of the copper alloy sheet after electrolytic polishing. In addition, the measurement can also be performed on the cross-section along the rolling direction after the copper alloy sheet is filled with resin and finish-machined by mechanical polishing and polishing (colloidal silica). The measurement areas in these cross-sections and on the surface are set to approximately 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 surface, a value obtained by averaging the measurements of multiple fields can also be used.

[0055] Measurement points with a reliability index CI value of 0.1 or more among the crystal orientation data obtained in this way according to the EBSD method can be set as the objects of analysis, and the intensity can be measured at 5° intervals for the polar angle in the range of 0 to 90° and the azimuthal angle in the range of 0 to 355°. Then, based on the inverse pole figure of the atomic plane with respect to the normal direction (ND) of the surface, the maximum value of the intensity of the inverse pole figure can be obtained.

[0056] [3] The ratio of the orientation angles with an intensity of 2.0 or less in the inverse pole figure of the crystal plane facing the normal direction (ND) of the surface to all the orientation angles

[0057] The copper alloy sheet of the present invention is preferably such that the proportion of the orientation angles with an inverse pole figure intensity of 2.0 or less for the crystal plane with respect to the normal direction (ND) of the sheet surface, measured on the sheet surface of the copper alloy sheet and obtained by crystal orientation analysis according to the EBSD method, in all the orientation angles is 50% or more. By setting this proportion to 50% or more, the orientation change for a specific orientation angle is small, and thus the anisotropy change is small. Therefore, the drawability of the copper alloy sheet can be further improved, and in particular, the ears formed at the edge of the drawn part can be further reduced. Here, from the viewpoint of improving the drawability of the copper alloy sheet, the proportion of the orientation angles with an intensity of 2.0 or less in all the orientation angles is preferably 52% or more, preferably 60% or more, and more preferably 70% or more.

[0058] The proportion of the orientation angles with an intensity of 2.0 or less in all the orientation angles of the copper alloy sheet can be obtained by calculating the proportion of the number of orientation angles with an intensity of 2.0 or less in the inverse pole figure of the crystal plane with respect to the normal direction (ND) of the sheet surface, obtained by crystal orientation analysis according to the EBSD method, in the total number of measured orientation angles.

[0059] [4] Tensile strength of the copper alloy sheet

[0060] 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. Thus, even when the copper alloy sheet is used for small and thin parts such as electrical / electronic parts and in-vehicle parts for automobiles, a desired tensile strength can still be obtained, and therefore 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 drawing also becomes higher, and there is a tendency for the copper alloy sheet to break easily during the drawing process. 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 600 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.

[0061] [5] Conductivity of the copper alloy sheet

[0062] 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, preferably 33% 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 conductivity obtained by the two measurements is set as the measured value of the conductivity.

[0063] [6] An example of the manufacturing method of the copper alloy sheet

[0064] 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.

[0065] An example of the manufacturing method of the copper alloy sheet of the present invention is to perform at least sequentially on a copper alloy material having an alloy composition equivalent to that 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], an intermediate annealing step [Step 4], a first cold rolling step [Step 5], a melting treatment step [Step 6], an aging heat treatment step [Step 7], a second cold rolling step [Step 8], and a low-temperature annealing step [Step 9].

[0066] (i) Melting and casting step [Step 1]

[0067] 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 (ingot) of a specified shape (for example, a thickness of 30 mm, a width of 100 mm, and a length of 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 is not necessarily 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.

[0068] (ii) Reheating step [Step 2]

[0069] The reheating step [Step 2] is a step of performing heat treatment on the ingot after the casting step [Step 1]. The conditions for the heat treatment in the reheating step [Step 2] are preferably as follows: the reaching temperature (heat treatment temperature) is in the range of 900 °C or higher and 1050 °C, and the holding time (heat treatment 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 900 °C, dynamic recrystallization cannot occur sufficiently in the subsequent hot rolling step [Step 3], so it is likely to result in an uneven structure. On the other hand, when the reaching temperature exceeds 1050 °C, the grain boundaries become weak, so the hot-rolled material after the hot rolling step [Step 3] is likely to crack.

[0070] (iii) Hot rolling step [Step 3]

[0071] 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 where dynamic recrystallization occurs. For example, the rolling temperature can be set to 700 °C or higher, and the total reduction ratio (total reduction rate) can be set to 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 an uneven structure.

[0072] The "reduction ratio" (reduction rate) in this specification is a value obtained by dividing the value obtained by subtracting the cross-sectional area after rolling from the cross-sectional area before rolling by the cross-sectional area before rolling, multiplying by 100, and expressing it as a percentage, as shown in the following formula.

[0073] [Reduction ratio] = {([Cross-sectional area before rolling] - [Cross-sectional area after rolling]) / [Cross-sectional area before rolling]} × 100 (%)

[0074] As an example, when the rolling temperature in the hot rolling step [Step 3] is 700 °C, the total reduction ratio calculated based on the cross-sectional area before rolling and the cross-sectional area after one operation completed until reaching 700 °C can be set as the total reduction ratio (total reduction rate), and the total reduction ratio (total reduction rate) in the temperature range from the heat treatment temperature to 700 °C in the reheating step [Step 2] can be set to 50% or higher.

[0075] In addition, the temperature of the ingot during the hot rolling step [Step 3] can be measured with a radiation thermometer.

[0076] (iv) Intermediate annealing step [Step 4]

[0077] The intermediate annealing step [Step 4] is a step of performing heat treatment on the hot-rolled material after the hot rolling step [Step 3] according to the alloy composition.

[0078] The annealing conditions in the intermediate annealing step [Step 4] are preferably as follows: the reaching temperature is in the range of above 800°C and below 1000°C, and the holding time at the reaching temperature is in the range of above 30 seconds and below 1 hour. By using heat treatment at a high temperature above 800°C to grow grains, it is possible to suppress the development of the rolled texture obtained in the following first cold rolling step [Step 5] and the recrystallized texture obtained in the subsequent melting treatment step [Step 6]. Thereby, when obtaining an inverse pole figure of the crystal plane with respect to the normal direction (ND) of the plate surface by crystal orientation analysis according to the EBSD method, the maximum value of the intensity of the inverse pole figure becomes a relatively low value of 3.0 or less. Therefore, the anisotropy of the copper alloy sheet can be reduced, and as a result, the drawability of the copper alloy sheet can be improved. Here, when the reaching temperature is lower than 800°C, the growth of grains becomes insufficient, and the anisotropy of the copper alloy sheet increases, so the drawability of the copper alloy sheet decreases. In particular, from the viewpoint of further reducing the maximum value of the intensity of the inverse pole figure when obtaining an inverse pole figure of the crystal plane with respect to the normal direction (ND) of the plate surface by crystal orientation analysis according to the EBSD method, the reaching temperature in the intermediate annealing step [Step 4] is preferably 850°C or higher, more preferably 900°C or higher. On the other hand, since the material may be partially melted, it is not desirable for the reaching temperature to exceed 1000°C.

[0079] In addition, compared with the heat treatment temperature, the heat treatment time (holding time at the reaching temperature) in the intermediate annealing step [Step 4] has a smaller influence on the anisotropy of the copper alloy sheet. Therefore, it can be carried out in the range of above 30 seconds and below 1 hour according to the characteristics of equipment such as a continuous moving annealing furnace or a batch furnace. Here, when the holding time at the reaching temperature is less than 30 seconds, the growth of grains becomes insufficient. On the other hand, even if the holding time at the reaching temperature is longer than 1 hour, the change in grains becomes smaller. Therefore, from the viewpoint of productivity, heat treatment for a longer time is not desirable.

[0080] Preferably, after performing the intermediate annealing step [Step 4], the cold-rolled material is cooled from the reaching temperature to a temperature of 300°C or lower at which new precipitation is less likely to occur. At this time, the cooling of the cold-rolled material can be carried out, for example, at a cooling rate of 1°C / s or more. As an example, it can be cooled by water cooling.

[0081] It is possible to perform face milling to remove the surface of the hot-rolled material after performing the hot-rolling step [Step 3] or the intermediate annealing step [Step 4]. By performing face milling, it is possible to remove the oxide film and defects on the surface generated in the hot-rolling step [Step 3] or the intermediate annealing step [Step 4]. The conditions for face milling may be the conditions usually carried out, and there is no particular limitation. The amount removed from the surface of the hot-rolled material by face milling can be appropriately adjusted according to the oxidation state of the surface. For example, it can be set to about 1 mm to 5 mm from the surface back of the hot-rolled material.

[0082] (v) First cold rolling step [Step 5]

[0083] The first cold rolling step [Step 5] is a step of performing cold rolling on the hot-rolled material after performing the intermediate annealing step [Step 4]. Here, the rolling in the first cold rolling step [Step 5] is carried out in two stages.

[0084] Among them, the rolling in the first stage is to roll the hot-rolled material in the same direction as the rolling direction in the hot-rolling step [Step 3]. Here, when the plate thicknesses before and after the rolling in the first stage are set to t0 and t1 respectively, the processing rate d1 in the first stage is represented by the following formula (1).

[0085] d1 = 100×(t0 - t1) / t0 ···(1)

[0086] In addition, the rolling in the second stage is to roll the cold-rolled material after performing the rolling in the first stage. The rolling direction in the second stage of rolling may be the same as or different from the rolling direction in the first stage of rolling. When the plate thickness after the rolling in the second stage is set to t2, the processing rate d2 in the second stage is represented by the following formula (2).

[0087] d2 = 100×(t1 - t2) / t1 ···(2)

[0088] At this time, the processing rates d1 and d2 are adjusted such that the ratio (d1 / d2) of the processing rate d1 in the first stage to the processing rate d2 in the second stage falls within the range of 0.3 or more and 2.0 or less. If the ratio (d1 / d2) of the processing rate d1 to the processing rate d2 exceeds the range of 0.3 or more and 2.0 or less, when obtaining an inverse pole figure of the crystal plane with respect to the normal direction (ND) of the plate surface, the maximum value of the intensity of the inverse pole figure increases, resulting in an increase in the anisotropy of the material. Therefore, the drawability of the copper alloy sheet decreases, and in particular, the ears formed at the edges of the drawn parts become larger. From the viewpoint of reducing the ears formed at the edges of the drawn parts, the ratio (d1 / d2) of the processing rate d1 to the processing rate d2 is preferably in the range of 0.5 or more and 1.5 or less, more preferably in the range of 0.7 or more and 1.3 or less, and even more preferably in the range of 0.9 or more and 1.1 or less. In particular, by setting the ratio (d1 / d2) of the processing rate d1 to the processing rate d2 to be in the range of 0.5 or more and 1.5 or less, when obtaining an inverse pole figure of the crystal plane with respect to the normal direction (ND) of the plate surface by crystal orientation analysis according to the EBSD method, the proportion of the orientation angles with an intensity of 2.0 or less in all the orientation angles can be made 50% or more.

[0089] In addition, the total processing rate d0 in the first cold rolling step [step 5] can be expressed by the following formula (3) and is preferably 80% or more. When the total processing rate d0 in the first cold rolling step [step 5] is less than 80%, since sufficient strain is not introduced, a recrystallized structure with uneven crystal grain sizes is likely to form in the subsequent melting treatment step [step 6]. As a result, during the drawing process, the copper alloy sheet is likely to break due to stress concentration, which may lead to a decrease in the processability of the copper alloy sheet.

[0090] d0 = 100×(t0―t2) / t0 ···(3)

[0091] (vi) Melting treatment step [step 6]

[0092] The melting treatment step [Step 6] is a step of performing heat treatment on the cold-rolled material after the first cold rolling step [Step 5] to recrystallize it and then cooling it. Here, the conditions of the heat treatment in the melting treatment step [Step 6] 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 7] 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 coarsens, resulting in a tendency for the tensile strength of the copper alloy sheet to decrease.

[0093] The melted material after the melting treatment step [Step 6] is preferably cooled immediately. More specifically, the cooling of the melted material after the melting treatment step [Step 6] is preferably carried out at a cooling rate of 40 °C / s or higher. 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 7], and thus there is a tendency for the tensile strength of the copper alloy sheet to decrease.

[0094] (vii) Aging heat treatment step [Step 7]

[0095] The aging heat treatment step [Step 7] 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 7] 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 coarsen, resulting in a tendency for the tensile strength of the copper alloy sheet to easily decrease.

[0096] (viii) Second cold rolling step [Step 8]

[0097] The second cold rolling step [Step 8] is a step of further cold rolling the cold-rolled material after the aging heat treatment step [Step 7]. Here, the total processing rate in the second cold rolling step [Step 8] is preferably in the range of 5% or more and 20% or less. Here, when the total processing rate is less than 5%, the amount of work hardening becomes small, so it becomes difficult to obtain the effect of improving the tensile strength of the copper alloy sheet. In addition, when the total processing rate is greater than 20%, the rolling texture develops and the anisotropy of the copper alloy sheet increases. As a result, when obtaining an inverse pole figure of the crystal plane with respect to the normal direction (ND) of the plate surface by crystal orientation analysis according to the EBSD method, the maximum value of the intensity of the inverse pole figure becomes greater than 3.0, and the drawability of the copper alloy sheet decreases, or the copper alloy sheet becomes easily broken during the drawing process.

[0098] (ix) Low-temperature annealing step [Step 9]

[0099] The low-temperature annealing step [Step 9] is an annealing step of performing heat treatment on the cold-rolled material after the second cold rolling step [Step 8]. The conditions of the heat treatment in this low-temperature annealing step [Step 9] are preferably: the reaching temperature is in the range of 200°C or more and 600°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 200°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 600°C or when the holding time at the reaching temperature exceeds 30 minutes, the work hardening caused by cold rolling disappears.

[0100] In addition, the heating and cooling rates before and after the annealing in the low-temperature annealing step [Step 9] are not particularly limited. For example, they can be set in the range of 1°C / s or more and 100°C / s or less.

[0101] [7] Use of the copper alloy sheet

[0102] The copper alloy sheet of the present invention is preferably a copper alloy sheet for drawing. That is, the copper alloy sheet of the present invention is particularly suitable for performing drawing to obtain drawn parts, for example, suitable for forming drawing parts for electronic devices and in-vehicle devices of automobiles. 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, batteries, probe needles, gas shut-off valves, etc. for electronic devices and in-vehicle devices of automobiles, which require support for high performance, high current, and miniaturization.

[0103] The above has described the embodiments of the present invention. However, 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.

[0104] [Examples]

[0105] Next, in order to make the effects of the present invention more clear, examples and comparative examples of the present invention will be described. However, the present invention is not limited to these examples of the present invention.

[0106] (Examples 1 to 21 and Comparative Examples 1 to 10 of the Present Invention)

[0107] The following melting and casting steps [Step 1] are carried out to obtain ingots: various copper alloy materials having the alloy compositions shown in Table 1 are melted, cooled in an atmospheric environment, and cast. After carrying out a reheating step [Step 2] on this ingot, a hot rolling step [Step 3] is immediately carried out to obtain a hot-rolled material. The reheating step [Step 2] is 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] is carried out in a temperature range of 700 °C or more and 1000 °C or less, and the total processing rate is made 50% or more, and the rolling is carried out in such a way that the long side direction of the ingot becomes the rolling direction. An intermediate annealing step [Step 4] is carried out on the rolled material after carrying out the hot rolling step [Step 3], and then it is cooled to room temperature by water cooling. The intermediate annealing step [Step 4] is carried out with the reaching temperature and holding time recorded in Table 2.

[0108] For the cooled hot-rolled material, surface cutting is carried out to remove about 1 mm to 2 mm from both the front and back surfaces to remove the surface oxide film, and then the first cold rolling step [Step 5] is carried out. The first cold rolling step [Step 5] is carried out in two stages under the conditions of the processing rate d1 in the first stage, the plate thickness t1 after rolling in the first stage, the processing rate d2 in the second stage, the plate thickness t2 after rolling in the second stage, and the ratio (d1 / d2) of the processing rate in the first stage to the processing rate in the second stage recorded in Table 2, and in such a way that the long side direction of the hot-rolled material becomes the rolling direction.

[0109] A melting treatment step [Step 6] is carried out, and it is cooled to room temperature at a cooling rate of 100 °C / s. The melting treatment step [Step 6] is carried out with the reaching temperature and holding time recorded in Table 2 for the cold-rolled material after carrying out the first cold rolling step [Step 5].

[0110] The aging heat treatment step [Step 7] is carried out. Next, the second cold rolling step [Step 8] is carried out to obtain a rolled material with a sheet thickness of 0.20 mm. The aging heat treatment step [Step 7] is to perform heat treatment on the cooled melt-treated material at the arrival temperature and holding time described in Table 2. The second cold rolling step [Step 8] is carried out under the conditions of the sheet thickness after rolling and the total processing rate described in Table 2 in such a way that the long side direction becomes the rolling direction.

[0111] The low-temperature annealing step [Step 9] is carried out to produce the copper alloy sheet of the present invention. The low-temperature annealing step [Step 9] is to perform heat treatment on the rolled material after the second cold rolling step [Step 8] at the arrival temperature and holding time described in Table 2.

[0112] On the other hand, regarding Comparative Example 10, a copper alloy sheet is produced without carrying out the intermediate annealing step [Step 4].

[0113] In addition, in Table 1, Sn (tin), Zn (zinc), Mg (magnesium), Fe (iron), and Cr (chromium) among the constituent components other than copper (Cu), Ni (nickel), and Si (silicon) are set as optional addition components. Further, 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, so as to make the fact that the corresponding component is not contained or even if contained, it is below the detection limit value clearer.

[0114] [Various measurement and evaluation methods]

[0115] The copper alloy sheets of the above-described examples of the present invention and comparative examples are used to perform the characteristic evaluations described below. The evaluation conditions for each characteristic are as follows.

[0116] [1] Maximum value of the intensity of the inverse pole figure of the crystal plane with respect to the normal direction (ND) of the plate surface

[0117] The maximum value of the intensity of the inverse pole figure of the crystal plane with respect to the normal direction (ND) of the plate surface of the copper alloy sheet is obtained from the crystal orientation analysis data calculated by 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 type analytical electron microscope (JSM-7001FA manufactured by JEOL Ltd.) for the copper alloy sheets obtained in the examples of the present invention and comparative examples. The measurement is carried out for a sample obtained by mirror-polishing the surface (plate surface) of the copper alloy sheet by electrolytic polishing at a step size of 0.5 μm in a field of view of about 400 μm × 800 μm.

[0118] Measurement points with a reliability index CI value of 0.1 or more among the crystal orientation data obtained by the EBSD method are set as the objects of analysis. Intensities are measured at 5° intervals for the polar angle in the range of 0 to 90° and the azimuthal angle in the range of 0 to 355°, respectively, to obtain an inverse pole figure of the atomic plane with respect to the normal direction (ND) of the plate surface. In this embodiment, for this inverse pole figure of the atomic plane with respect to the normal direction (ND) of the plate surface, the maximum value of the intensity is obtained, and a qualified grade is set when the maximum value of the intensity of this inverse pole figure is 3.0 or less. The results are shown in Table 3. In addition, the rolling direction (RD) in this embodiment is based on the rolling direction in the second cold rolling step [Step 8].

[0119] [2] The ratio of the azimuthal angles with an intensity of 2.0 or less among all azimuthal angles

[0120] The ratio of the azimuthal angles with an intensity of 2.0 or less in the copper alloy sheet among all azimuthal angles is the ratio of the number of azimuthal angles with an intensity of 2.0 or less among all measured azimuthal angles obtained from the above inverse pole figure of the atomic plane with respect to the normal direction (ND) of the plate surface. A qualified grade is set when this ratio is 50% or more. The results are shown in Table 3.

[0121] [3] Measurement of the tensile strength of the copper alloy sheet

[0122] The measurement of the tensile strength is 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 when stretched in the direction parallel to the rolling direction is set as the measured value. The test pieces are cut from the test material in such a way that the direction parallel to the rolling direction becomes the long side direction. In this embodiment, a qualified grade is set when the tensile strength is in the range of 500 MPa or more and 900 MPa or less. The results are shown in Table 3.

[0123] [4] Measurement of the conductivity of the copper alloy sheet

[0124] The conductivity of the copper alloy sheet is measured twice using the four-terminal method, and the average value of the conductivity obtained from the two measurements is set as the measured value of the conductivity. The results are shown in Table 3.

[0125] [5] Evaluation of the drawability of the copper alloy sheet

[0126] The drawability of the copper alloy sheet is tested using a blank with a diameter of 45 mm formed by stamping and blanking from a copper alloy sheet with a thickness of 0.20 mm. Lubricating oil (trade name: PRETON R-303P, manufactured by SUGIMURA Chemical Industry Co., Ltd.) is applied to the surface of the blank. Then, it is installed in a die with a shoulder radius of curvature of 3 mm, and a punch with a cylindrical tip diameter of 30 mm, a corner radius of curvature of 3 mm at the tip, and a punch-die clearance of 0.27 mm is pressed into the center of the blank to perform the first draw operation.

[0127] Furthermore, for an example where no fracture occurred during the first draw operation, the blank after the first draw operation is installed in a die with a shoulder radius of curvature of 3 mm with the centers of the blank and the die aligned, and a punch with a cylindrical tip diameter of 20 mm, a corner radius of curvature of 3 mm at the tip, and a punch-die clearance of 0.27 mm is pressed into the center of the blank to perform the second draw operation, and a cylindrical cup is obtained as the drawn part.

[0128] For the obtained drawn part, as Figure 1 (a) shows, a line segment L1 is drawn from the center C of the bottom surface 11 of the drawn part 1 to one side in the rolling direction X of the copper alloy sheet forming the bottom surface, and this line segment L1 is set as the angle reference (0°). In addition, for the side surface 12 of the drawn part 1 at the position where this line segment L1 abuts, the height from the bottom surface 11 to the edge 13 is measured, and this height is set as H0. Next, a line segment L2 is drawn from the center C of the bottom surface 11 of the drawn part 1 in the direction of an angle of 45° clockwise with respect to the line segment L1. For the side surface 12 of the drawn part 1 at the position where this line segment L1 abuts, the height from the bottom surface 11 to the edge 13 is measured, and this height is set as H 45 . Similarly, line segments L3 - L8 are drawn from the center C in the directions of angles of 90°, 135°, 180°, 225°, 270°, and 315° clockwise with respect to the line segment L1. For the side surface 12 of the drawn part 1 at the positions where these line segments L3 - L8 abut, as Figure 1 (b) shows, the heights from the bottom surface 11 to the edge 13 are measured respectively, and these heights are set as H 90 、H 135 、H 180 、H 225 、H 270 、H 315 .

[0129] Using these heights H0, H 45 、H 90 、H 135 、H 180 、H 225 、H270 and H 315 , the size E [%] of the undulation (ear) at the edge of the drawn part is calculated according to the following formulas (4) to (6).

[0130] H1 = (2 × H0 + H 90 + H 180 + H 270 ) / 5 ··· (4)

[0131] H2 = (H 45 + H 135 + H 225 + H 315 ) / 4 ··· (5)

[0132] E = (H1 ― H2) / {(H1 + H2) / 2} × 100 ··· (6)

[0133] In addition, for the size of the undulation (ear) at the edge of the drawn part, the evaluation is carried out according to the following evaluation criteria. The results are shown in Table 3.

[0134] <Evaluation Criteria for the Size of the Undulation (Ear) at the Edge of the Drawn Part>

[0135] "4" (excellent): when the size of the undulation (ear) is 3.0% or less

[0136] "3" (good): when the size of the undulation (ear) exceeds 3.0% and is 6.0% or less

[0137] "2" (acceptable): when the size of the undulation (ear) exceeds 6.0% and is 10.0% or less

[0138] "1" (unacceptable): when the size of the undulation (ear) exceeds 10.0% and when the blank fractures during the drawing process

[0139] [Table 1]

[0140]

[0141] [Table 2]

[0142]

[0143] [Table 3]

[0144]

[0145] Based on the results in Tables 1 to 3, the alloy compositions of the copper alloy sheets of Examples 1 to 21 of the present invention are within the appropriate range of the present invention. At the same time, the maximum value of the intensity of the inverse pole figure of the crystal plane with respect to the normal direction (ND) of the plate surface 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 deep drawability is also evaluated as "2", "3", or "4".

[0146] Therefore, the copper alloy sheets of Examples 1 to 21 of the present invention have high tensile strength and high conductivity, and can obtain excellent deep drawability. In particular, the ears formed at the edges of the deep drawn parts can be reduced.

[0147] In particular, when comparing the copper alloy sheets of Examples 1 and 2 of the present invention, the ratio (d1 / d2) of the processing rate d1 in the first stage to the processing rate d2 in the second stage in the first cold rolling step [Step 5] of the copper alloy sheet of Example 1 of the present invention falls within the preferred range of 0.5 or more and 1.5 or less, and is a smaller value than Example 2 with this ratio of 1.6. At this time, the proportion of the orientation angle with a strength of 2.0 or less in the inverse pole figure of the copper alloy sheet of Example 1 of the present invention is within the range of 50% or more in all orientation angles, which is greater than Example 2 with this ratio of 48%. Further, in the copper alloy sheet of Example 1 of the present invention, the undulation (ears) at the edges of the deep drawn parts also becomes smaller than that of Example 2.

[0148] In addition, when comparing the copper alloy sheets of Examples 1 and 3 of the present invention, the reaching temperature of the intermediate annealing step [Step 4] of the copper alloy sheet of Example 3 of the present invention falls within the preferred range of 850 °C or more and 1000 °C or less, and is a higher temperature than Example 1 with this reaching temperature of 800 °C. At this time, the maximum value of the intensity of the inverse pole figure of the crystal plane with respect to the normal direction (ND) of the plate surface of the copper alloy sheet of Example 3 of the present invention is within the more preferred upper limit of 2.5 or less, and becomes smaller than that of Example 1. Further, in the copper alloy sheet of Example 3 of the present invention, the undulation (ears) at the edges of the deep drawn parts also becomes smaller than that of Example 1.

[0149] In addition, when comparing the copper alloy sheets of Examples 3 and 4 of the present invention, the reaching temperature of the intermediate annealing step [Step 4] of the copper alloy sheet of Example 4 of the present invention falls within the more preferred range of 900 °C or more and 1000 °C or less, and is a higher temperature than Example 3 with this reaching temperature of 850 °C. At this time, the maximum value of the intensity of the inverse pole figure of the crystal plane with respect to the normal direction (ND) of the plate surface of the copper alloy sheet of Example 4 of the present invention is within the further more preferred upper limit of 2.0 or less, and becomes smaller than that of Example 3. Further, in the copper alloy sheet of Example 4 of the present invention, the undulation (ears) at the edges of the deep drawn parts also becomes smaller than that of Example 3.

[0150] In addition, when comparing the copper alloy sheets of Example 1 and Example 5 of the present invention, the ratio (d1 / d2) of the working rate d1 in the first stage to the working rate d2 in the second stage of the first cold rolling step [Step 5] of the copper alloy sheet of Example 5 of the present invention is 0.8, which falls within the more preferred range of 0.7 or more and 1.3 or less, and is a lower ratio than that of Example 1 of the present invention where this ratio (d1 / d2) is 1.5. At this time, the proportion of the orientation angles with a strength of 2.0 or less in the inverse pole figure of the copper alloy sheet of Example 5 of the present invention is within the preferred lower limit of 60% or more, and becomes higher than that of Example 1 of the present invention. Further, in the copper alloy sheet of Example 5 of the present invention, the undulation (ears) at the edge of the drawn part also becomes smaller than that of Example 3 of the present invention.

[0151] In addition, when comparing the copper alloy sheets of Example 1 and Example 6 of the present invention, the ratio (d1 / d2) of the working rate d1 in the first stage to the working rate d2 in the second stage of the first cold rolling step [Step 5] of the copper alloy sheet of Example 6 of the present invention is 0.4, which is outside the preferred range of 0.5 or more and 1.5 or less. Therefore, in the copper alloy sheet of Example 6 of the present invention, the proportion of the orientation angles with a strength of 2.0 or less in the inverse pole figure is small, and the undulation (ears) at the edge of the drawn part also becomes larger.

[0152] The reaching temperature of the intermediate annealing step [Step 4] of the copper alloy sheets of Examples 7 to 11 of the present invention is 1000 °C, which falls within the more preferred range of 900 °C or more and 1000 °C or less. In addition, the ratio (d1 / d2) of the working rate d1 in the first stage to the working rate d2 in the second stage of the first cold rolling step [Step 5] of the copper alloy sheets of Examples 7 to 11 of the present invention is 1.0, which falls within the further more preferred range of 0.9 or more and 1.1 or less. Therefore, the evaluation results of the drawing workability of the copper alloy sheets of Examples 7 to 11 are all "4".

[0153] In addition, when comparing the copper alloy sheets of Example 7 and Example 8 of the present invention, the reaching temperature of the melting treatment step [Step 6] of the copper alloy sheet of Example 7 of the present invention is 800 °C, and the tensile strength is a higher value compared to Example 8 where the reaching temperature of the melting treatment step [Step 6] is as low as 700 °C. The reason for this is that it is considered that in Example 8, due to the lower reaching temperature of the melting treatment step [Step 6], the solid solution amounts of Ni and Si required for precipitation strengthening are insufficient.

[0154] In addition, when comparing the copper alloy sheets of Example 7 and Example 9 of the present invention, the reaching temperature of the melting treatment step [Step 6] of the copper alloy sheet of Example 7 of the present invention is 800°C, and the tensile strength is a higher value compared to Example 9 of the present invention where the reaching temperature of the melting treatment step [Step 6] is as high as 1000°C. The reason is that it is considered that in Example 9 of the present invention, due to the relatively high reaching temperature of the melting treatment step [Step 6], the grain coarsening occurs.

[0155] In addition, for the copper alloy sheet of Example 10 of the present invention, since the reaching temperature of the aging heat treatment step [Step 7] is as low as 400°C, both the tensile strength and the conductivity are relatively low values. This is considered to be because the reaching temperature of the aging heat treatment step [Step 7] is relatively low, resulting in insufficient precipitation amount.

[0156] In addition, for the copper alloy sheet of Example 11 of the present invention, since the reaching temperature of the aging heat treatment step [Step 7] is as high as 560°C, although it has a high conductivity, the tensile strength is a relatively low value. This is considered to be because the conductivity increases due to the increase in the precipitation amount, while on the other hand, the precipitates coarsen and the tensile strength decreases.

[0157] For the copper alloy sheets of Examples 12 to 14 of the present invention, since the rolling reduction rate of the second cold rolling step [Step 8] is as high as 20%, although they have a high tensile strength, the evaluation results of the drawability are all "2". The reason why the evaluation result of the drawability becomes "2" like this is considered to be that the texture develops due to cold rolling.

[0158] In addition, when comparing the copper alloy sheets of Example 12 and Example 13 of the present invention, since the reaching temperature of the low-temperature annealing step [Step 9] of the copper alloy sheet of Example 13 is higher than that of Example 12, it becomes easier to undergo strain recovery compared to Example 12. As a result, the tensile strength of the copper alloy sheet of Example 13 becomes lower than that of Example 12.

[0159] In addition, when comparing the copper alloy sheets of Example 12 and Example 14 of the present invention, since the reaching temperature of the low-temperature annealing step [Step 9] of the copper alloy sheet of Example 14 is lower than that of Example 12, it becomes less likely to undergo strain recovery compared to Example 12. As a result, the tensile strength of the copper alloy sheet of Example 14 becomes higher than that of Example 12.

[0160] Regarding Examples 15 to 20 of the present invention, the contents of the essential additive components Ni and Si and the contents of the optional additive elements are within the scope of the present invention, so it can be seen that the desired effects are obtained in the same way as in Examples 1 to 14 of the present invention.

[0161] On the other hand, in all of the copper alloy sheets of Comparative Examples 1 to 10, at least any one of the alloy composition, tensile strength, electrical conductivity, and the maximum value of the intensity of the inverse pole figure of the crystal plane with respect to the normal direction (ND) of the plate surface is outside the appropriate range of the present invention. Therefore, the tensile strength or the electrical conductivity does not reach the qualified grade, or the comprehensive evaluation of the drawing processability is evaluated as "1".

[0162] In particular, the copper alloy sheets of Comparative Examples 1, 2, and 9 have a lower reaching temperature in the intermediate annealing step [Step 4], so that the maximum value of the intensity of the inverse pole figure of the crystal plane with respect to the normal direction (ND) of the plate surface exceeds 3.0, and the evaluation of the drawing processability is also evaluated as "1".

[0163] In addition, the total reduction rate of the copper alloy sheet of Comparative Example 3 is high in the second cold rolling step [Step 8], so that the undulation (ears) at the edge of the drawn part becomes large. This is considered to be due to the high total reduction rate in the second cold rolling step [Step 8], resulting in the development of the aggregate structure.

[0164] In addition, the copper alloy sheet of Comparative Example 4 breaks during the first drawing process because the content of Ni (nickel) in the alloy composition is more than the range of the present invention and the tensile strength is high.

[0165] In addition, the tensile strength of the copper alloy sheet of Comparative Example 5 does not reach the qualified grade because the content of Si (silicon) in the alloy composition is less than the range of the present invention.

[0166] In addition, the copper alloy sheet of Comparative Example 6 is an example where the electrical conductivity does not reach the qualified grade.

[0167] In addition, the copper alloy sheet of Comparative Example 7 breaks during the first drawing process because the content of Si (silicon) in the alloy composition is more than the range of the present invention and the tensile strength is high. In addition, the electrical conductivity also does not reach the qualified grade.

[0168] In addition, the tensile strength of the copper alloy sheet of Comparative Example 8 does not reach the qualified grade because the content of Ni (nickel) in the alloy composition is less than the range of the present invention.

[0169] In addition, since the intermediate annealing step [Step 4] is not performed on the copper alloy sheet of Comparative Example 10, the maximum value of the intensity of the inverse pole figure of the crystal plane with respect to the normal direction (ND) of the plate surface exceeds 3.0, and the evaluation of the drawing processability is also evaluated as "1".

[0170] Reference numerals

[0171] 1: Drawn part

[0172] 11: Bottom surface of the drawn part

[0173] 12: Side surface of the drawn part

[0174] 13: Edge of the drawn part

[0175] C: Center of the bottom surface of the drawn part

[0176] H0, H 45 , H 90 , H 135 , H 180 , H 225 , H 270 , H 315 : Height from the bottom surface to the edge

[0177] L1 to L8: Line segments drawn along the bottom surface of the drawn part

[0178] X: Rolling direction of the copper alloy sheet

Claims

1. 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 consisting of Cu and unavoidable impurities; wherein, the maximum value of the intensity of the inverse pole figure of the crystal plane with respect to the normal direction (ND) of the front surface of the copper alloy sheet measured on the front 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, The proportion of the orientation angles with an intensity of 2.0 or less in the inverse pole figure among all the orientation angles is 50% or more.

3. The copper alloy sheet according to claim 1, wherein The 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 deep drawing, which is composed of the copper alloy sheet according to any one of claims 1 to 3.

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

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