WO2024225165A1 - Copper alloy sheet material, copper alloy sheet material for drawing, and drawn product - Google Patents

Abstract

Provided are a copper alloy sheet material, a copper alloy sheet material for drawing, and a drawn product, which have high tensile strength and high electrical conductivity. The present invention makes it possible to realize excellent drawability and, in particular, to reduce ears formed on the edges of the drawn product.　The copper alloy sheet material has an alloy composition containing Ni in the range from 1.00 mass% to 5.00 mass% and Si in the range from 0.20 mass% to 1.30 mass%, with the remainder being Cu and unavoidable impurities. When a plate surface of the copper alloy sheet material is measured by the EBSD method for crystal orientation analysis, the maximum strength value found in the inverse polar figure pertaining to a crystal plane oriented in the normal direction (ND) of the plate surface obtained from the analysis is 3.0 or less. The copper alloy sheet material has a tensile strength in the range from 500 MPa to 900 MPa, and an electroconductivity of 30% IACS or more.

Description

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

The present invention relates to copper alloy sheet materials, copper alloy sheet materials for drawing, and drawn products.

Copper alloy sheets are used, for example, in electronic devices or automotive connectors, lead frames, relays, switches, sockets, shield cases, shield cans, camera module cases, vibration device cases, heat dissipation parts for liquid crystal and organic electroluminescence displays, batteries, probe pins, and gas shielding valves, and are often subjected to press processing such as punching, bending, drawing, and stretching.

As an example of a copper alloy used in such press processing, Patent Document 1 discloses a copper alloy containing, by mass%, 1.0-3.6% Ni, 0.2-1.0% Si, 0.05-3.0% Sn, 0.05-3.0% Zn, with the remainder being copper and unavoidable impurities, and having an average crystal grain size of 25 μm or less, and having a texture in which, as measured by the SEM-EBSP method, the average area ratio of Cube orientation {001}<100> is 20-60%, and the average total area ratio of the three orientations, Brass orientation {011}<211>, S orientation {123}<634>, and Copper orientation {112}<111>, is 20-50%, and having a KAM value of 1.00-3.00. In Patent Document 1, it is said that by 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, it is possible to obtain a copper alloy with small strength anisotropy and excellent bending workability.

Patent Document 2 discloses a Cu-Ni-Si copper alloy sheet material with excellent deep drawability and fatigue resistance, which contains 1.0-3.0 mass% Ni, 1/6-1/4 mass% Si of the Ni mass%, and the remainder Cu and unavoidable impurities, has a Goss orientation density of 2.0-6.0% measured by EBSD using a scanning electron microscope with a backscattered electron diffraction image system, an average KAM value of 0.9-1.5°, and a ratio (Lσ/L) of the total special grain boundary length Lσ of the special grain boundaries to the total grain boundary length L of the crystal grain boundaries of 60-70%. Patent Document 2 claims that the fatigue properties and drawability of the copper alloy sheet material can be improved by controlling the Goss orientation density, KAM value, and total special grain boundary length of the Cu-Ni-Si alloy sheet.

JP 2011-162848 A JP 2012-122114 A

　In recent years, with the increasing performance, current density, and miniaturization of electronic devices and in-vehicle devices, higher mechanical properties and electrical conductivity (or thermal conductivity) are being required for the press-processed products that make up these components. In particular, for drawn parts used in electronic devices and in-vehicle devices, such as connectors, lead frames, relays, switches, sockets, shield cases, shield cans, camera module cases, vibration device cases, heat dissipation parts for liquid crystal and organic EL displays, batteries, probe pins, and gas barrier valves, there is a demand for copper alloy sheet materials made of materials that combine higher mechanical properties and electrical conductivity (or thermal conductivity) than the copper alloys of brass and nickel silver that have traditionally been used.

Here, "drawing" refers to a type of metal sheet forming method, and typically refers to a processing method in which a punch is pressed into a thin metal sheet to form bottomed containers of various shapes, such as cylinders, square tubes, and cones. Also, "drawn products" refers to processed products formed by drawing, and are characterized by having no seams in the processed products formed. Note that "drawn products" also include processed products formed by combining drawing with other processing methods different from drawing, such as bending, crushing, and twisting.

Increasing the depth of this drawing process often makes processing difficult because the material is more likely to break. Even if the process can be completed without breaking, the edges of the resulting drawn product are likely to have large ripples (ears). In particular, in drawing processes where the depth of the drawn product is large relative to the diameter of the punch used during processing, the product must be formed in multiple stages of drawing, and the ears are particularly likely to become large. If large ears are formed here, not only will the shape of the drawn product be damaged, but adjacent ears will tend to overlap during the drawing process, or cracks will tend to form between adjacent ears. Furthermore, if large ears are formed, an additional process will be required to remove the ears from the drawn product, so there is a demand for copper alloy sheet materials that can reduce the ears formed on the edges of drawn products.

In this regard, in the Cu-Ni-Si alloy described in Patent Document 1, 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) is reduced by accumulating the Cube orientation. Therefore, in applications in which bending is performed with the rolling parallel direction and the rolling perpendicular direction as bending axes, such as connectors, terminals, switches, relays, and lead frames, anisotropy can be reduced by considering only these two directions. However, no consideration has been given to drawing, which is affected by anisotropy in all directions, not just the rolling parallel direction and the rolling perpendicular direction, much less the achievement of reducing the size of the ears formed on the edges of a drawn product while maintaining high tensile strength and high electrical conductivity, and no evaluation results of these properties have been shown. In this regard, the Cu-Ni-Si alloy of Patent Document 1 has an integrated Cube orientation, so that the mechanical properties along the direction at an angle of 45° to the rolling direction are significantly different from those along the rolling direction or perpendicular to the rolling direction. Therefore, when this copper alloy is used in drawing, large ears are formed on the edges of the resulting drawn product. Furthermore, the Cu-Ni-Si alloy described in Patent Document 1 is manufactured by carrying out the following steps in the order of casting, ingot facing, soaking, hot rolling, cold rolling, solution treatment (recrystallization annealing), age hardening, cold rolling, and low-temperature annealing, and does not include an intermediate annealing step to coarsen the crystal grain size after the hot rolling step.

In addition, although Patent Document 2 describes that the drawing workability (deep drawing workability) of copper alloy sheet material has been improved, the evaluation of drawing workability is only performed by evaluating the presence or absence of fracture when a punch with a large spherical tip having a diameter of 10 mm is pressed against a blank material taken from the copper alloy sheet material to produce a cup, and only the presence or absence of fracture is evaluated under gentle drawing conditions, and no evaluation results are shown under drawing conditions in which the depth of the drawn product is large relative to the punch diameter during processing. Furthermore, Patent Document 2 does not consider the ears formed on the edge of the drawn product at all. Furthermore, there is no disclosure about achieving both high tensile strength and high electrical conductivity while reducing the size of the ears formed on the edge of the drawn product, and no evaluation results of these properties are shown. Furthermore, the copper alloy sheet material described in Patent Document 2 is manufactured by performing the steps of hot rolling, cold rolling, solution treatment, aging, pickling, final cold rolling, and low-temperature annealing in that order, and does not include an intermediate annealing step that coarsens the crystal grain size after the hot rolling step.

The present invention has been made in consideration of the above problems, and aims to provide a copper alloy sheet material, a copper alloy sheet material for drawing, and a drawn product that has high tensile strength and high electrical conductivity, and also has excellent drawing workability, in particular, that can reduce the lugs formed on the edges of drawn products.

The inventors have discovered that in a copper alloy sheet material having an alloy composition containing 1.00% by mass or more and 5.00% by mass or less of Ni, 0.20% by mass or more and 1.30% by mass or less of Si, with the remainder being Cu and unavoidable impurities, by setting the maximum value of the intensity of the inverse pole figure for the crystal plane facing the normal direction (ND) of the sheet surface of the copper alloy sheet material obtained by crystal orientation analysis using the EBSD method described below to 3.0 or less, setting the tensile strength to a range of 500 MPa or more and 900 MPa or less, and setting the electrical conductivity to 30% IACS or more, the tensile strength and electrical conductivity of the copper alloy sheet material can be increased, and the drawing workability can be improved, and in particular, the ears formed on the edges of the drawn product can be made smaller, thereby completing the present invention.

(1) A copper alloy sheet material having an alloy composition containing Ni in the range of 1.00% by mass to 5.00% by mass, Si in the range of 0.20% by mass to 1.30% by mass, and the remainder being Cu and unavoidable impurities, in which the maximum value of the strength of the inverse pole figure for the crystal plane facing the normal direction (ND) of the sheet surface obtained by crystal orientation analysis using the EBSD method measured on the sheet surface of the copper alloy sheet material is 3.0 or less, the tensile strength is in the range of 500 MPa or more to 900 MPa or less, and the electrical conductivity is 30% IACS or more.

(2) The copper alloy sheet material described in (1) above, in which the proportion of azimuth angles at which the strength is 2.0 or less among all azimuth angles in the inverse pole figure is 50% or more.

(3) The copper alloy sheet material according to (1) or (2) above, 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 ranging from 0.10% by mass to 1.00% by mass.

(4) A copper alloy sheet material for drawing, comprising the copper alloy sheet material described in any one of (1) to (3) above.

(5) A drawn product obtained by drawing the copper alloy sheet material described in any one of (1) to (3) above.

The present invention provides a copper alloy sheet material, a copper alloy sheet material for drawing, and a drawn product that has high tensile strength and high electrical conductivity, and also has excellent drawing workability, in particular, that can reduce the lugs formed on the edges of drawn products.

FIG. 1 is a diagram for explaining a method for measuring the size of an ear (waviness) formed on the edge of a typical drawn product of a copper alloy sheet material, FIG. 1(a) is a bottom view of the drawn product when a line segment extending in the radial direction from the center position of the bottom surface of the drawn product to the position of the circular outline of the bottom surface is drawn while rotating at 45°, and FIG. 1(b) is a perspective view of the drawn product of FIG. 1(a), showing the height from the bottom surface position of the drawn product to the position of the ear present on the upper edge.

Next, an embodiment of the present invention will be described. The following description shows an example of an embodiment of the present invention and does not limit the scope of the claims.

The copper alloy sheet material according to the present invention has an alloy composition containing Ni in the range of 1.00% by mass to 5.00% by mass, Si in the range of 0.20% by mass to 1.30% by mass, with the remainder being Cu and unavoidable impurities, and has a maximum strength value of the inverse pole figure for the crystal plane facing the normal direction (ND) of the sheet surface obtained from crystal orientation analysis by the EBSD method measured on the sheet surface of the copper alloy sheet material of 3.0 or less, a tensile strength in the range of 500 MPa or more to 900 MPa or less, and an electrical conductivity of 30% IACS or more.

The copper alloy sheet material of the present invention contains at least Ni and Si in appropriate amounts, and is manufactured under appropriate manufacturing conditions to suppress the development of texture, thereby reducing the maximum value of the inverse pole figure strength to 3.0 or less, thereby reducing anisotropy and making it possible to reduce the lugs formed on the edges of drawn products, i.e., the waviness of the edges of drawn products. Furthermore, the copper alloy sheet material of the present invention contains at least Ni and Si in appropriate amounts, thereby making it possible to increase the tensile strength and electrical conductivity of the copper alloy sheet material. Therefore, the copper alloy sheet material of the present invention can provide a copper alloy sheet material, a copper alloy sheet material for drawing, and a drawn product that have high tensile strength and high electrical conductivity, and can obtain excellent drawing workability, in particular, making it possible to reduce the lugs formed on the edges of drawn products.

[1] Alloy composition of copper alloy sheet The copper alloy sheet of the present invention has an alloy composition containing, as essential components, 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.
The reasons for limiting the alloy composition of the copper alloy sheet material will be explained below.

(Ni: 1.00% by mass or more and 5.00% by mass or less)
Ni (nickel) is an important component that has the effect of increasing the tensile strength of the copper alloy sheet material, and is contained in the range of 1.00 mass % to 5.00 mass %. If the Ni content is less than 5.00 mass%, a high tensile strength of 500 MPa or more cannot be obtained. On the other hand, if the Ni content is more than 5.00 mass%, the tensile strength of the copper alloy sheet material exceeds 900 MPa and the tensile strength of the copper alloy sheet material is increased due to the addition of Si. In addition, when the Ni content is more than 5.00 mass %, the electrical conductivity of the copper alloy sheet material is reduced. The rate decreases. Therefore, from the viewpoint of increasing the tensile strength and electrical conductivity of the copper alloy sheet material and making it difficult for cracks to occur in the drawn product, the Ni content is in the range of 1.00 mass% or more and 5.00 mass% or less, The range is preferably 1.00% by mass or more and 4.50% by mass, more preferably 1.50% by mass or more and 4.50% by mass, and further preferably 2.00% by mass or more and 4.00% by mass or more. In particular, from the viewpoint of further increasing the tensile strength of the copper alloy sheet, the Ni content is preferably 1.50 mass % or more. From the viewpoint of further increasing the Ni content, the Ni content is preferably 4.50 mass % or less.

(Si: 0.20 mass% or more and 1.30 mass% or less)
Silicon (Si) is an important component that has the effect of increasing the tensile strength of the copper alloy sheet material, and is contained in the range of 0.20 mass % to 1.30 mass %. If the Si content is less than 10 mass%, a high tensile strength of 500 MPa or more cannot be obtained. If the Si content is more than 1.30 mass%, the tensile strength of the copper alloy sheet material exceeds 900 MPa and the tensile strength of the copper alloy sheet material becomes higher than 900 MPa. In addition, when the Si content is more than 1.30 mass %, the electrical conductivity of the copper alloy sheet material is reduced. The rate decreases. Therefore, from the viewpoint of increasing the tensile strength and electrical conductivity of the copper alloy sheet material and making it difficult for cracks to occur in the drawn product, the Si content is in the range of 0.20 mass% or more and 1.30 mass% or less, The range is preferably 0.20 mass % or more and 1.10 mass % or less, more preferably 0.30 mass % or more and 1.10 mass % or less, and further preferably 0.50 mass % or more and 1. In particular, from the viewpoint of further increasing the tensile strength of the copper alloy sheet, the Si content is preferably 0.30 mass% or more. From the viewpoint of further increasing the above, the Si content is preferably 1.10 mass % or less.

<Optionally Added Ingredients>
Furthermore, the copper alloy sheet of the present invention may further contain at least one optional additive component selected from the group consisting of Sn, Zn, Mg, Fe and Cr in a total amount of 0.10 mass% or more and 1.00 mass% or less.

(Sn: 0.10 mass% or more and 0.30 mass% or less)
Sn (tin) is a component that has the effect of improving stress relaxation resistance. In order to exert such an effect, the Sn content is preferably 0.10 mass% or more. When the Sn content exceeds 0.30 mass %, the electrical conductivity tends to decrease. Therefore, the Sn content is preferably in the range of 0.10 mass % or more and 0.30 mass % or less.

(Zn: 0.10% by mass or more and 0.50% by mass or less)
Zn (zinc) is a component that has the effect of improving the adhesion and migration properties of Sn plating. To exert such an effect, the Zn content is preferably 0.10 mass% or more. However, when the Zn content exceeds 0.50 mass%, the electrical conductivity tends to decrease. Therefore, the Zn content is preferably in the range of 0.10 mass% to 0.50 mass%. .

(Mg: 0.10% by mass or more and 0.30% by mass or less)
Magnesium (Mg) is a component that has the effect of improving stress relaxation resistance. To exert such an effect, the Mg content is preferably 0.10 mass% or more. When the Mg content exceeds 0.30 mass %, the electrical conductivity tends to decrease. Therefore, the Mg content is preferably in the range of 0.10 mass % or more and 0.30 mass % or less.

(Fe: 0.05% by mass or more and 0.30% by mass or less)
Fe (iron) is a component that has the effect of suppressing the coarsening of crystal grains after dynamic recrystallization in the hot rolling step [step 3] described later, and the effect of preventing surface roughness of a drawn product. In order to exert this effect, the Fe content is preferably 0.05 mass% or more. If the Fe content exceeds 0.30 mass%, coarse crystals containing Fe are generated during casting. Therefore, the Fe content is preferably in the range of 0.05% by mass to 0.30% by mass.

(Cr: 0.05% by mass or more and 0.30% by mass or less)
Cr (chromium) is a component that has the effect of suppressing the coarsening of crystal grains after dynamic recrystallization in the hot rolling step [step 3] described later, and the effect of preventing surface roughness of drawn products. In order to exert this effect, the Cr content is preferably 0.05 mass% or more. If the Cr content exceeds 0.30 mass%, coarse crystals containing Cr may be generated during casting. Therefore, the Cr content is preferably in the range of 0.05 mass % or more and 0.30 mass % or less.

(Total content of optional added components: 0.10% by mass or more and 1.00% by mass or less)
In order to obtain the above-mentioned effects of the optional components, the total content of these optional components is preferably 0.10% by mass or more. On the other hand, since the electrical conductivity decreases when these optional components are contained in large amounts, the total content of the optional components is preferably 1.00% by mass or less.

(balance: Cu and unavoidable impurities)
The copper alloy constituting the copper alloy sheet material has an alloy composition consisting of Cu (copper) and inevitable impurities other than the above-mentioned components. The "unavoidable impurities" referred to here are generally those present in the raw materials of metal products or those inevitably mixed in during the manufacturing process, which are essentially unnecessary but are allowed because they are in small amounts and do not affect the properties of the metal product. Examples of components that can be cited as inevitable impurities include nonmetallic elements such as sulfur (S), carbon (C), and oxygen (O), and metallic elements such as antimony (Sb). The upper limit of the content of these components can be, for example, 0.05% by mass for each of the above components, and 0.20% by mass for the total amount of the above components.

[2] Maximum value of the intensity of the inverse pole figure for the crystal plane facing the normal direction (ND) of the sheet surface In the copper alloy sheet of the present invention, the maximum value of the intensity of the inverse pole figure for the crystal plane facing the normal direction (ND) of the sheet surface obtained by crystal orientation analysis by the EBSD method measured on the sheet surface of the copper alloy sheet is 3.0 or less. When the maximum value of the intensity of this inverse pole figure exceeds 3.0, the orientation to any atomic plane (crystal plane) becomes high, and the anisotropy becomes high depending on the oriented atomic plane. That is, from the viewpoint of improving the drawing workability of the copper alloy sheet, particularly from the viewpoint of reducing the ear (waviness) formed on the edge of the drawn product, it is important to suppress the orientation to 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 among the inverse poles. Here, the maximum value of the intensity of the inverse pole figure for the crystal plane facing the normal direction (ND) of the sheet surface is preferably 2.6 or less, more preferably 2.5 or less, and even more preferably 2.0 or less, from the viewpoint of improving the drawing workability. On the other hand, the lower limit of the maximum value of the intensity of the inverse pole figure is not particularly defined, but can be 1.0 or 1.2.

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) from the crystal orientation data continuously measured using an EBSD detector attached to a high-resolution scanning analytical electron microscope (JSM-7001FA, manufactured by JEOL Ltd.). "EBSD" is an abbreviation for Electron Backscatter Diffraction, and is a crystal orientation analysis technique that uses the reflected electron Kikuchi line diffraction that occurs when an electron beam is irradiated on a copper alloy sheet material, which is a sample, in a scanning electron microscope (SEM). "OIM Analysis" is an analysis software for data measured by EBSD. The measurement can be performed on the plate surface of the electrolytically polished copper alloy sheet material. The measurement may also be performed on a cross section along the rolling direction of a copper alloy sheet material that has been filled with resin and finished by mechanical polishing and buff polishing (colloidal silica). The measurement area on these cross sections and plate surfaces is approximately 400 μm x 800 μm, and measurements can be performed with a step size of 0.5 μm. If the above field size cannot be obtained due to the sample size in both cross-section and plate surface measurements, measurements can be taken in multiple fields of view and the average value can be used.

Among the crystal orientation data obtained in this way by the EBSD method, measurement points where the reliability index CI value is 0.1 or more are the subject of analysis, and the intensity is measured at 5° increments for polar angles in the range of 0 to 90° and azimuthal angles in the range of 0 to 355°. The maximum intensity value of the inverse pole figure can then be obtained from the inverse pole figure for the atomic plane in the normal direction (ND) of the plate surface.

[3] Proportion of azimuth angles with an intensity of 2.0 or less in all azimuth angles in an inverse pole figure for a crystal plane facing the normal direction (ND) of the sheet surface In the copper alloy sheet of the present invention, the proportion of azimuth angles with an intensity of 2.0 or less in all azimuth angles in an inverse pole figure for a crystal plane facing the normal direction (ND) of the sheet surface obtained by crystal orientation analysis using the EBSD method measured on the sheet surface of the copper alloy sheet is preferably 50% or more. By making this proportion 50% or more, the orientation to a specific azimuth angle becomes smaller, and the anisotropy becomes smaller, so that the drawing workability of the copper alloy sheet can be further improved, and in particular, the ear formed on the edge of the drawn product can be further reduced. Here, the proportion of the azimuth angle with an intensity of 2.0 or less in all azimuth angles is preferably 52% or more, more preferably 60% or more, and more preferably 70% or more from the viewpoint of improving the drawing workability of the copper alloy sheet.

The percentage of all orientation angles of the copper alloy sheet material where the strength is 2.0 or less can be determined by calculating the percentage of the number of orientation angles where the strength is 2.0 or less to the total number of orientation angles measured in the inverse pole figure for the crystal plane facing the normal direction (ND) of the sheet surface obtained from the crystal orientation analysis using the EBSD method described above.

[4] Tensile strength of copper alloy sheet The copper alloy sheet of the present invention has a tensile strength in the range of 500 MPa or more and 900 MPa or less. As a result, even when the copper alloy sheet is used for small or thin parts such as electric and electronic parts and automotive parts, the desired tensile strength can be obtained, so that the copper alloy sheet can be suitably used for various drawn products. On the other hand, when the tensile strength exceeds 900 MPa, the fracture resistance of the copper alloy sheet also increases, but the deformation resistance during drawing also increases, and the copper alloy sheet tends to break easily in the drawing test. Therefore, the tensile strength of the copper alloy sheet is in the range of 500 MPa or more and 900 MPa or less, and among them, it is preferable that it is in the range of 600 MPa or more and 900 MPa or less. Here, the tensile strength can be, for example, the tensile strength when pulled in a direction parallel to the rolling direction. The tensile strength was measured using two test pieces of No. 13B specified in JIS Z2241, cut out so that the longitudinal direction was parallel to the rolling direction, and the average value of the tensile strengths obtained from the two test pieces was taken as the measured value of the tensile strength.

[5] Electrical conductivity of copper alloy sheet The copper alloy sheet of the present invention has an electrical conductivity of 30% IACS or more. As a result, the copper alloy sheet has high electrical conductivity, and can be used for drawn products that require electromagnetic shielding and heat dissipation. Therefore, the electrical conductivity of the copper alloy sheet is 30% IACS or more, and preferably 33% IACS or more. Here, the electrical conductivity (IACS; International Annealed Copper Standard) is measured twice using a four-terminal method, and the average value of the electrical conductivity obtained by the two measurements is taken as the measured electrical conductivity.

[6] An example of a manufacturing method for a copper alloy sheet The above-mentioned copper alloy sheet can be realized by controlling the alloy composition and the manufacturing process in combination, and the manufacturing process is not particularly limited. Among them, the following method can be mentioned as an example of a manufacturing process that can obtain such high tensile strength and excellent drawing workability.

One example of a method for manufacturing the copper alloy sheet material of the present invention is to sequentially carry out at least a melting and casting process [step 1], a reheating process [step 2], a hot rolling process [step 3], an intermediate annealing process [step 4], a first cold rolling process [step 5], a solution treatment process [step 6], an aging heat treatment process [step 7], a second cold rolling process [step 8] and a low-temperature annealing process [step 9] on a copper alloy material having an alloy composition equivalent to that of the copper alloy sheet material described above.

(i) Melting and Casting Process [Process 1]
In the melting and casting process [Step 1], a copper alloy material having an alloy composition equivalent to the above-mentioned alloy composition is melted and cast to produce an ingot of a predetermined shape (for example, 30 mm thick, 100 mm wide, and 150 mm long). In the melting and casting process [Step 1], it is preferable to melt and cast the copper alloy material in the air, in an inert gas atmosphere, or in a vacuum using a high-frequency melting furnace. Note that the alloy composition of the copper alloy material may not necessarily be completely the same as that of the copper alloy sheet material produced by adhering to or volatilizing from the melting furnace depending on the added components in each manufacturing process, but it has substantially the same alloy composition as that of the copper alloy sheet material.

(ii) Reheating step [Step 2]
The reheating step [step 2] is a step of performing a heat treatment on the ingot after the casting step [step 1]. The conditions of the heat treatment in the reheating step [step 2] are the reached temperature (heat treatment It is preferable that the temperature at which the heat treatment is performed is in the range of 900° C. to 1050° C., and the holding time at the reached temperature (heat treatment time) is in the range of 1 hour to 10 hours. In the hot rolling process [Step 3], dynamic recrystallization does not occur sufficiently, so the structure is likely to be non-uniform. On the other hand, if the reaching temperature exceeds 1050°C, the grain boundaries become weak, and the thermal Cracks are likely to occur in the hot-rolled material after the cold rolling step [step 3].

(iii) Hot rolling step [Step 3]
The hot rolling step [step 3] is a step of producing a hot-rolled material by hot rolling the ingot that has been subjected to the reheating step [step 2] until it has a predetermined thickness. The conditions of the hot rolling step [step 3] can be set under conditions under which dynamic recrystallization occurs, for example, the rolling temperature can be set to 700°C or higher and the total processing rate (total rolling reduction rate) can be set to 50% or higher. On the other hand, if dynamic recrystallization does not occur sufficiently in the hot rolling step [step 3], the obtained copper alloy sheet material is likely to have a non-uniform structure.

The "working rate" (rolling reduction) in this specification is a value obtained by subtracting the cross-sectional area after rolling from the cross-sectional area before rolling, dividing the value by the cross-sectional area before rolling, and multiplying the result by 100, expressed as a percentage, and is expressed by the following formula.
[Working rate] = {([Cross-sectional area before rolling] - [Cross-sectional area after rolling]) / [Cross-sectional area before rolling]} x 100 (%)

As an example, if the rolling temperature in the hot rolling process [Step 3] is 700°C, the total processing rate (total rolling reduction rate) can be the sum of the processing rate calculated from the cross-sectional area before rolling begins and the cross-sectional area after all passes completed before reaching 700°C, and the total processing rate (total rolling reduction rate) in the temperature range from the heat treatment temperature in the reheating process [Step 2] to 700°C can be 50% or more.

The temperature of the ingot during the hot rolling process [Step 3] can be measured with a radiation thermometer.

(iv) Intermediate annealing step [Step 4]
The intermediate annealing step [step 4] is a step in which the hot-rolled material after the hot working step [step 3] is subjected to a heat treatment according to the alloy composition.

The annealing conditions in the intermediate annealing step [step 4] are preferably such that the temperature reached is in the range of 800°C or higher and 1000°C or lower, and the holding time at the reached temperature is in the range of 30 seconds or higher and 1 hour or lower. By growing the crystal grains by heat treatment at a high temperature of 800°C or higher, the development of the rolling texture obtained in the first cold rolling step [step 5] described later and the recrystallization texture obtained in the subsequent solution treatment step [step 6] is suppressed, and when an inverse pole figure for the crystal plane facing the normal direction (ND) of the sheet surface is obtained by crystal orientation analysis using the EBSD method, the maximum value of the intensity of the inverse pole figure becomes a low value of 3.0 or less. Therefore, the anisotropy of the copper alloy sheet material can be reduced, and as a result, the drawing workability of the copper alloy sheet material can be improved. Here, when the reaching temperature is less than 800°C, the growth of the crystal grains becomes insufficient and the anisotropy of the copper alloy sheet material increases, so that the drawing workability of the copper alloy sheet material decreases. In particular, the temperature reached in the intermediate annealing step [step 4] is preferably 850°C or higher, and more preferably 900°C or higher, from the viewpoint of further reducing the maximum value of the intensity of the inverse pole figure obtained for the crystal plane facing the normal direction (ND) of the sheet surface by crystal orientation analysis using the EBSD method. On the other hand, it is not desirable to reach a temperature exceeding 1000°C, since there is a possibility of partial melting of the material.

In addition, the heat treatment time (holding time at the reached temperature) in the intermediate annealing step [step 4] has less effect on the anisotropy of the copper alloy sheet material than the heat treatment temperature, and can be carried out in the range of 30 seconds to 1 hour depending on the characteristics of the equipment, such as a continuous running annealing furnace or a batch furnace. Here, if the holding time at the reached temperature is less than 30 seconds, the growth of the crystal grains will be insufficient. On the other hand, even if the holding time at the reached temperature is longer than 1 hour, the change in the crystal grains will be small, so heat treatment for a longer period than this is not desirable from the standpoint of productivity.

After the intermediate annealing step [step 4], it is preferable to cool the cold-rolled material from the target temperature to a temperature of 300°C or less, which is a temperature at which new precipitation is unlikely to occur. At this time, the cold-rolled material can be cooled at a cooling rate of, for example, 1°C/s or more, and as an example, it can be cooled by water cooling.

The hot-rolled material after the hot working step [step 3] or the intermediate annealing step [step 4] may be subjected to facing to remove the surface. By performing facing, it is possible to remove the oxide film or defects on the surface that occurred during the hot working step [step 3] or the intermediate annealing step [step 4]. The conditions for facing can be any conditions that are normally used, and are not particularly limited. The amount of material removed from the surface of the hot-rolled material by facing can be adjusted appropriately based on the oxidation state of the surface, and can be, for example, about 1 mm to 5 mm from both the front and back sides of the hot-rolled material.

(v) First cold rolling step [step 5]
The first cold rolling step [step 5] is a step of cold rolling the hot rolled material after the intermediate annealing step [step 4]. Here, the rolling in the first cold rolling step [step 5] is performed in two stages.

Among these, the first stage rolling rolls the hot rolled material in the same direction as the rolling direction in the hot working step [step 3]. Here, the processing rate _d1 in the first stage is expressed by the following formula (1), where _t0 and _t1 are the plate thicknesses before and after the first stage rolling, respectively.
d ₁ = 100×(t ₀ - t ₁ )/t ₀ ...(1)

In addition, the second stage rolling is performed by rolling the cold rolled material after the first stage rolling. The rolling direction in the second stage rolling may be the same as or different from the rolling direction in the first stage rolling. The processing rate _d2 in the second stage is expressed by the following formula (2) when the plate thickness after the second stage rolling is _t2 .
d ₂ =100×(t ₁ -t ₂ )/t ₁ ...(2)

At this time, the processing rates _d1 and _d2 are adjusted so that the ratio ( _d1 / _d2 ) of the processing rate _d1 of the first stage to the processing rate _d2 of the second stage is in the range of 0.3 to 2.0. If the ratio ( _d1 / _d2 ) of the processing rate _d1 to the processing rate _d2 is out of the range of 0.3 to 2.0, when an inverse pole figure for a crystal plane facing the normal direction (ND) of the sheet surface is obtained, the maximum value of the intensity of the inverse pole figure becomes large, and the anisotropy of the material increases, so that the drawing workability of the copper alloy sheet material decreases, and in particular, the ear formed on the edge of the drawn product becomes large. From the viewpoint of reducing the ear formed on the edge of the drawn product, the ratio ( _d1 / _d2 ) of the processing rate _d1 to the processing rate _d2 is preferably in the range of 0.5 to 1.5, more preferably in the range of 0.7 to 1.3, and even more preferably in the range of 0.9 to 1.1. In particular, by setting the ratio of the processing rate _d1 to the processing rate _d2 ( _d1 / _d2 ) in the range of 0.5 to 1.5, when an inverse pole figure for a crystal plane facing the normal direction (ND) of the sheet surface is obtained by crystal orientation analysis using the EBSD method, the proportion of azimuth angles with an intensity of 2.0 or less among all azimuth angles can be made 50% or more.

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. If the total processing rate _d0 in the first cold rolling step [step 5] is less than 80%, sufficient strain is not introduced, so that the crystal grain size is likely to be non-uniform in the recrystallized structure in the solution treatment step [step 6] described later. As a result, the copper alloy sheet material is likely to break due to stress concentration during drawing, which may lead to a decrease in the workability of the copper alloy sheet material.
d ₀ =100×(t ₀ -t ₂ )/t ₀ ...(3)

(vi) Solution treatment step [Step 6]
The solution treatment step [step 6] is a step of cooling the cold-rolled material after the first cold rolling step [step 5] by heat treatment to recrystallize it. Here, the conditions of the heat treatment in the solution treatment step [step 6] can be, for example, the ultimate temperature in the range of 700 ° C. to 1000 ° C., and the holding time at the ultimate temperature in the range of 10 seconds to 60 seconds. Here, when the ultimate temperature is less than 700 ° C. or the holding time is less than 10 seconds, the precipitation strengthening amount in the aging heat treatment step [step 7] described later decreases, and the tensile strength of the copper alloy sheet material decreases. On the other hand, when the ultimate temperature exceeds 1000 ° C. or the holding time exceeds 60 seconds, the crystal grain size becomes coarse, and the tensile strength of the copper alloy sheet material tends to decrease.

It is preferable to immediately cool the solution-treated material after the solution treatment step [step 6]. More specifically, it is preferable to cool the solution-treated material after the solution treatment step [step 6] at a cooling rate of 40°C/s or more. Here, if the cooling rate is less than 40°C/s, coarse precipitates are generated during cooling, which reduces the amount of precipitation strengthening in the aging heat treatment step [step 7], and the tensile strength of the copper alloy sheet material tends to decrease.

(vii) Aging heat treatment step [Step 7]
The aging heat treatment step [step 7] is a step of precipitation strengthening by subjecting the cooled solution-treated material to heat treatment. Here, the conditions of the heat treatment in the aging heat treatment step [step 7] are that the ultimate temperature is in the range of 400°C or more and 600°C or less, and the holding time at the ultimate temperature is in the range of 1 hour or more and 10 hours or less. Here, when the ultimate temperature is less than 400°C or the holding time is less than 1 hour, it becomes difficult to obtain precipitation strengthening, and the tensile strength and electrical conductivity of the copper alloy sheet material tend to decrease. On the other hand, when the ultimate temperature exceeds 600°C or the holding time exceeds 10 hours, the precipitates become coarse, and the tensile strength of the copper alloy sheet material tends to decrease.

(viii) Second cold rolling step [step 8]
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 working ratio in the second cold rolling step [step 8] is preferably in the range of 5% to 20%. Here, when the total working ratio is less than 5%, the amount of work hardening is small, so that it is difficult to obtain the effect of increasing the tensile strength of the copper alloy sheet. In addition, when the total working ratio is greater than 20%, the rolling texture develops and the anisotropy of the copper alloy sheet increases, so that when an inverse pole figure for a crystal plane facing the normal direction (ND) of the sheet surface is obtained by crystal orientation analysis using the EBSD method, the maximum value of the strength of the inverse pole figure becomes greater than 3.0, and the drawing workability of the copper alloy sheet decreases, or the copper alloy sheet becomes more likely to break during drawing.

(ix) Low temperature annealing step [Step 9]
The low-temperature annealing step [step 9] is a step of annealing in which the cold-rolled material after the second cold rolling step [step 8] is subjected to heat treatment. The conditions of the heat treatment in this low-temperature annealing step [step 9] are preferably such that the attained temperature is in the range of 200 ° C. or more and 600 ° C. or less, and the holding time at the attained temperature is in the range of 10 seconds or more and 30 minutes or less. Here, when the attained temperature is less than 200 ° C. or the holding time is less than 10 seconds, the strain remaining in the cold-rolled material after annealing becomes excessive, so that the drawing workability of the copper alloy sheet material is reduced. On the other hand, when the attained temperature exceeds 600 ° C. or the holding time at the attained temperature exceeds 30 minutes, the work hardening due to cold rolling disappears.

In addition, the heating and cooling rates before and after annealing in the low-temperature annealing step [step 9] are not particularly limited, but can be in the range of 1°C/s to 100°C/s, for example.

[7] Uses of copper alloy sheet material The copper alloy sheet material of the present invention is preferably used as a copper alloy sheet material for drawing. That is, the copper alloy sheet material of the present invention is particularly suitable for obtaining a drawn product by drawing, and is suitable for forming drawn parts used in electronic devices and automotive on-board devices, for example. More specifically, it is suitable for use in connectors, lead frames, relays, switches, sockets, shield cases, shield cans, camera module cases, vibration device cases, heat dissipation parts for liquid crystal and organic EL displays, batteries, probe pins, gas shielding valves, etc. for electronic devices and automotive on-board devices that require high performance, high current, and miniaturization.

The above describes an embodiment of the present invention, but the present invention is not limited to the above embodiment, and includes all aspects included in the concept of the present invention and the scope of the claims, and can be modified in various ways within the scope of the present invention.

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

(Invention Examples 1 to 21 and Comparative Examples 1 to 10)
Various copper alloy materials having the alloy composition shown in Table 1 were melted, and the melting and casting process [step 1] was performed to cast the melted copper alloy materials by cooling them in an air atmosphere. The ingots were then subjected to a reheating process [step 2] in which heat treatment was performed at an ultimate temperature (heat treatment temperature) of 1000°C and a holding time (heat treatment time) at the ultimate temperature of 1 hour, and then immediately subjected to a hot rolling process [step 3] in which the ingots were rolled so that the longitudinal direction of the ingots was the rolling direction and the total processing rate was 50% or more at a temperature range of 700°C to 1000°C to obtain hot-rolled materials. The rolled materials after the hot rolling process [step 3] were subjected to an intermediate annealing process [step 4] in which heat treatment was performed at the ultimate temperature and holding time shown in Table 2, and then cooled to room temperature by water cooling.

The cooled hot-rolled material was then subjected to facing to remove approximately 1 to 2 mm from both the front and back sides to remove the oxide film on the surface.Then, a first cold rolling process [Process ₅ ] was performed in which the hot-rolled material was rolled in two stages, with the longitudinal direction of the hot-rolled material being the rolling direction in all cases, under the conditions of the first-stage processing rate _d1 , the plate thickness after the first stage rolling _t1 , the second-stage processing rate _d2 , the plate thickness after the second stage rolling _t2 , and the ratio of the first-stage processing rate to the second-stage processing rate (d1/ _d2 ) as shown in Table 2.

After the first cold rolling process [Step 5], the cold-rolled material was subjected to a solution treatment process [Step 6] in which the material was heat-treated at the temperature and for the holding time shown in Table 2, and then cooled to room temperature at a cooling rate of 100°C/s.

The cooled solution-treated material was subjected to an aging heat treatment process [Process 7] in which heat treatment was performed at the attained temperature and for the holding time shown in Table 2, and then a second cold rolling process [Process 8] was performed in which the material was rolled so that the longitudinal direction was the rolling direction under the conditions of the plate thickness after rolling and the total processing rate shown in Table 2, to obtain a rolled material with a plate thickness of 0.20 mm.

The rolled material after the second cold rolling process [Step 8] was subjected to a low-temperature annealing process [Step 9] in which the material was heat-treated at the attained temperature and for the holding time shown in Table 2, to produce the copper alloy sheet material of the present invention.

On the other hand, for Comparative Example 10, the copper alloy sheet material was produced without performing the intermediate annealing step [step 4].

In addition, in Table 1, out of the components other than copper (Cu), Ni (nickel), and Si (silicon), Sn (tin), Zn (zinc), Mg (magnesium), Fe (iron), and Cr (chromium) are listed as optional added components. In addition, in Table 1, a horizontal line "-" is entered in the column for components that are not included in the alloy composition of the copper alloy material, to clarify that the corresponding component is not contained, or if it is contained, it is below the detection limit.

[Various measurement and evaluation methods]
The copper alloy sheets according to the above-mentioned invention examples and comparative examples were used to carry out the following characteristic evaluations. The evaluation conditions for each characteristic were as follows.

[1] Maximum value of inverse pole figure intensity for crystal planes facing the normal direction (ND) of the sheet surface The maximum value of the inverse pole figure intensity for crystal planes facing the normal direction (ND) of the sheet surface of the copper alloy sheet material was obtained from crystal orientation analysis data calculated using analysis software (TSL, OIM Analysis) from crystal orientation data continuously measured using an EBSD detector attached to a high-resolution scanning analytical electron microscope (JSM-7001FA, manufactured by JEOL Ltd.) for the copper alloy sheets obtained in the present invention and comparative examples. The measurement was performed with a step size of 0.5 μm in a field of view of about 400 μm x 800 μm for samples in which the surface (sheet surface) of the copper alloy sheet material was mirror-finished by electrolytic polishing.

Among the crystal orientation data thus obtained by the EBSD method, measurement points with a reliability index CI value of 0.1 or more were analyzed, and the strength was measured at 5° increments for polar angles in the range of 0 to 90° and azimuthal angles in the range of 0 to 355°, and an inverse pole figure for the atomic plane in the normal direction (ND) of the sheet surface was obtained. In this example, the maximum strength value of the inverse pole figure for the atomic plane in the normal direction (ND) of the sheet surface was obtained, and an inverse pole figure with a maximum strength value of 3.0 or less was determined to be at the pass level. The results are shown in Table 3. Note that the rolling direction (RD) in this example was based on the rolling direction in the second cold rolling process [Process 8].

[2] Proportion of azimuth angles with an intensity of 2.0 or less in all azimuth angles The proportion of azimuth angles with an intensity of 2.0 or less in all azimuth angles of the copper alloy sheet material was determined by calculating the proportion of the number of azimuth angles with an intensity of 2.0 or less among all azimuth angles measured in the inverse pole figure for the atomic plane in the normal direction (ND) of the sheet surface described above, and a proportion of 50% or more was determined to be acceptable. The results are shown in Table 3.

[3] Measurement of tensile strength of copper alloy sheet material The tensile strength was measured using two test pieces of JIS Z2241 No. 13B, cut out from the test material so that the longitudinal direction was parallel to the rolling direction, and the average value of the tensile strength obtained from the two test pieces when pulled in the direction parallel to the rolling direction was taken as the measured value. In this example, a tensile strength in the range of 500 MPa to 900 MPa was considered to be acceptable. The results are shown in Table 3.

[4] Measurement of electrical conductivity of copper alloy sheet The electrical conductivity of the copper alloy sheet was measured twice using the four-terminal method, and the average value of the electrical conductivity obtained by the two measurements was used as the measured value. The results are shown in Table 3.

[5] Evaluation of drawing workability of copper alloy sheet The drawing workability of the copper alloy sheet was evaluated by using a blank having a diameter of 45 mm formed by press punching from the obtained copper alloy sheet having a thickness of 0.20 mm, applying a lubricating oil (product name: Pleton R-303P, manufactured by Sugimura Chemical Industry Co., Ltd.) to the sheet surface, attaching the blank to a die having a shoulder radius of curvature of 3 mm, and pushing a punch having a cylindrical tip diameter of 30 mm, a tip corner radius of curvature of 3 mm, and a punch-to-die clearance of 0.27 mm into the center of the blank to perform a first drawing process.

Furthermore, in an example in which no cracks occurred in the first drawing process, the blank after the first drawing process was attached to a die with a shoulder radius of curvature of 3 mm so that the centers of the blank and die overlapped, and a punch with a cylindrical tip diameter of 20 mm, a tip corner radius of curvature of 3 mm, and a punch-to-die clearance of 0.27 mm was pressed into the center of the blank to perform the second drawing process, resulting in a cylindrical cup as the drawn product.

As shown in Fig. 1(a) for the obtained drawn product, a line segment _L1 was drawn from the center C of the bottom surface 11 of the drawn product 1 to one side of the rolling direction X of the copper alloy sheet material constituting the bottom surface, and this line segment _L1 was set as the reference angle (0°). In addition, for the side surface 12 of the drawn product 1 at the position where this line segment _L1 abuts, the height from the bottom surface 11 to the edge 13 was measured, and this height was set as _H0 . Next, a line segment _L2 was drawn from the center C of the bottom surface 11 of the drawn product 1 in a direction forming an angle of 45° clockwise with respect to the line segment _L1 , and for the side surface 12 of the drawn product 1 at the position where this line segment _L1 abuts, the height from the bottom surface 11 to the edge 13 was measured, and this height was set as _H45 . Similarly, line segments _L3 to _L8 were drawn from center C in directions forming angles of 90°, 135°, 180°, 225°, 270°, and 315° clockwise with line segment _L1 . For the side surface 12 of the drawn product 1 where these line segments _L3 to _L8 butted against each other, the heights from the bottom surface 11 to the edge 13 were measured as shown in FIG. 1(b), and these heights were determined as _H90 , _H135 , _H180 , _H225 , _H270 , and _H315 , respectively.

Using these heights H ₀ , H ₄₅ , H ₉₀ , H ₁₃₅ , H ₁₈₀ , H ₂₂₅ , H ₂₇₀ , and H ₃₁₅ , the magnitude E [%] of the waviness (ear) at the edge of the drawn product was calculated from the following formulas (4) to (6).
H ₁ = (2×H ₀ +H ₉₀ +H ₁₈₀ +H ₂₇₀ )/5 (4)
_H2 =( _H45 + _H135 + _H225 + _H315 )/4...(5)
E=(H ₁ - H ₂ )/{(H ₁ +H ₂ )/2}×100...(6)

The size of the waviness (edges) on the edges of the drawn products was also evaluated according to the following evaluation criteria. The results are shown in Table 3.

<Evaluation criteria for the size of waviness (edges) on the edges of drawn products>
"4" (Excellent): When the waviness (ear) is 3.0% or less; "3" (Good): When the waviness (ear) is more than 3.0% and less than 6.0%; "2" (Acceptable): When the waviness (ear) is more than 6.0% and less than 10.0%; "1" (Unacceptable): When the waviness (ear) is more than 10.0% and the blank breaks during drawing.

From the results in Tables 1 to 3, the copper alloy sheets of Examples 1 to 21 of the present invention have alloy compositions within the appropriate range of the present invention, a maximum value of the strength of the inverse pole figure for the crystal plane facing the normal direction (ND) of the sheet surface is 3.0 or less, a tensile strength is in the range of 500 MPa to 900 MPa, and an electrical conductivity is 30% IACS or more, and the drawing workability is also rated as "2," "3," or "4."

Therefore, the copper alloy sheet materials of Examples 1 to 21 of the present invention had high tensile strength and high electrical conductivity, and also had excellent drawing workability, and in particular, it was possible to reduce the ears formed on the edges of the drawn product.

In particular, when comparing the copper alloy sheets of Inventive Examples 1 and 2, the ratio (d1/ _d2 ) of the first-stage working rate d1 to the second-stage working rate d2 in the first cold rolling step [step ₅ ] of the copper alloy sheet of Inventive Example ₁ was in the preferred range of 0.5 to _1.5 , which was smaller than that of Inventive Example 2, in which this ratio was 1.6. In this case, the ratio of azimuth angles in the inverse pole figure where the intensity was 2.0 or less to all azimuth angles of the copper alloy sheet of Inventive Example 1 was in the range of 50% or more, which was larger than that of Inventive Example 2, in which this ratio was 48%. Furthermore, in the copper alloy sheet of Inventive Example 1, the waviness (ear) at the edge of the drawn product was also smaller than that of Inventive Example 2.

Comparing the copper alloy sheet materials of invention examples 1 and 3, the copper alloy sheet material of invention example 3 reached a temperature in the intermediate annealing step [step 4] within the preferred range of 850°C to 1000°C, which was higher than the temperature reached in invention example 1, which reached a temperature of 800°C. In this case, the copper alloy sheet material of invention example 3 had a maximum value of the intensity of the inverse pole figure for the crystal plane facing the normal direction (ND) of the sheet surface within a more preferred upper limit range of 2.5 or less, which was smaller than that of invention example 1. Furthermore, in the copper alloy sheet material of invention example 3, the waviness (ears) at the edge of the drawn product was also smaller than that of invention example 1.

Comparing the copper alloy sheet materials of Examples 3 and 4, the copper alloy sheet material of Example 4 of the present invention had an intermediate annealing step [Step 4] temperature that was in the more preferred range of 900°C to 1000°C, which was higher than the temperature of Example 3 of the present invention, which was 850°C. In this case, the copper alloy sheet material of Example 4 of the present invention had a maximum value of the intensity of the inverse pole figure for the crystal plane facing the normal direction (ND) of the sheet surface that was in the more preferred upper limit range of 2.0 or less, which was smaller than that of Example 3 of the present invention. Furthermore, in the copper alloy sheet material of Example 4 of the present invention, the waviness (ears) at the edge of the drawn product was also smaller than that of Example 3 of the present invention.

In addition, when comparing the copper alloy sheets of Examples 1 and 5, the copper alloy sheet of Example 5 of the present invention has a ratio ( _d1 / _d2 ) of the first-stage processing rate d1 to the second-stage processing rate _d2 in the first cold rolling step [step 5] of 0.8, which is within a more preferable range of 0.7 to 1.3, and is lower than that of Example ₁ of the present invention, in which this ratio ( _d1 / _d2 ) is 1.5. In this case, the copper alloy sheet of Example 5 of the present invention has a ratio of azimuth angles in which the intensity is 2.0 or less to all azimuth angles in the inverse pole figure of 60% or more, which is the preferable lower limit, and is higher than that of Example 1 of the present invention. Furthermore, in the copper alloy sheet of Example 5 of the present invention, the waviness (ear) at the edge of the drawn product is also smaller than that of Example 3 of the present invention.

In addition, when comparing the copper alloy sheets of Inventive Examples 1 and 6, the ratio (d1/ _d2) of the first-stage working rate _d1 to the second-stage working rate d2 in the first cold rolling step [step 5] of the copper alloy sheet of Inventive Example ₆ was 0.4, which was outside the preferred range of 0.5 to 1.5. Therefore, in the copper alloy sheet of Inventive Example 6, _the ratio of azimuth angles in which the intensity was 2.0 or less to all azimuth angles in the inverse pole figure was small, and the waviness (ears) at the edge of the drawn product was also large.

In the copper alloy sheets of Examples 7 to 11 of the present invention, the temperature reached in the intermediate annealing step [Step 4] was 1000° C., which was within the more preferable range of 900° C. or more and 1000° C. or less. In addition, in the copper alloy sheets of Examples 7 to 11 of the present invention, the ratio (d ₁ /d ₂ ) of the first-stage processing rate d ₁ to the second-stage processing rate d ₂ in the first cold rolling step [Step 5] was 1.0, which was within the more preferable 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 of the present invention were all "4".

Comparing the copper alloy sheet materials of Inventive Examples 7 and 8, the copper alloy sheet material of Inventive Example 7 had a higher tensile strength than Inventive Example 8, which had a lower temperature of 700°C in the solution treatment step [Step 6], because the temperature reached in the solution treatment step [Step 6] was 800°C. The reason for this is thought to be that in Inventive Example 8, the amount of Ni and Si in solid solution, which are necessary for precipitation strengthening, was insufficient due to the lower temperature reached in the solution treatment step [Step 6].

Comparing the copper alloy sheet materials of Inventive Examples 7 and 9, the copper alloy sheet material of Inventive Example 7 had a higher tensile strength than Inventive Example 9, which had a higher temperature of 1000°C in the solution treatment step [Step 6], since the temperature reached in the solution treatment step [Step 6] was 800°C. This is thought to be because the crystal grains in Inventive Example 9 became coarse due to the higher temperature reached in the solution treatment step [Step 6].

In addition, the copper alloy sheet material of Example 10 of the present invention had low tensile strength and electrical conductivity due to the low temperature reached in the aging heat treatment process [Step 7] of 400°C. This is thought to be because the amount of precipitation was insufficient due to the low temperature reached in the aging heat treatment process [Step 7].

In addition, the copper alloy sheet material of Example 11 of the present invention has a high electrical conductivity due to the high temperature reached in the aging heat treatment process [Step 7] of 560°C, but the tensile strength is low. This is thought to be because, while the electrical conductivity increases due to the increased amount of precipitation, the tensile strength decreases due to the coarsening of the precipitates.

The copper alloy sheets of Examples 12 to 14 of the present invention have high tensile strength due to the high processing rate of 20% in the second cold rolling process [Process 8], but the evaluation results for drawing workability were all "2." The reason for the evaluation result of drawing workability being "2" is thought to be that texture was developed by cold rolling.

In addition, when comparing the copper alloy sheet materials of invention examples 12 and 13, the copper alloy sheet material of invention example 13 reached a higher temperature in the low-temperature annealing step [step 9] than invention example 12, so the recovery of strain was more likely to proceed than in invention example 12. As a result, the tensile strength of the copper alloy sheet material of invention example 13 was lower than that of invention example 12.

In addition, when comparing the copper alloy sheet materials of invention examples 12 and 14, the copper alloy sheet material of invention example 14 reached a lower temperature in the low-temperature annealing step [step 9] than invention example 12, so strain recovery was less likely to occur than in invention example 12. As a result, the tensile strength of the copper alloy sheet material of invention example 14 was higher than that of invention example 12.

Invention Examples 15 to 20, the contents of the essential added components Ni and Si, and the contents of the optional added elements, were within the ranges of the present invention, and it can be seen that the desired effects were obtained, just like invention examples 1 to 14.

On the other hand, in the copper alloy sheets of Comparative Examples 1 to 10, at least one of the alloy composition, tensile strength, electrical conductivity, and maximum value of the inverse pole figure strength for the crystal plane facing the normal direction (ND) of the sheet surface was outside the appropriate range of the present invention, so the tensile strength or electrical conductivity did not reach the acceptable level, or the overall drawing workability was rated as "1."

In particular, in the copper alloy sheets of Comparative Examples 1, 2, and 9, the maximum value of the intensity of the inverse pole figure for the crystal plane facing the normal direction (ND) of the sheet surface exceeded 3.0 due to the low temperature reached in the intermediate annealing process [Process 4], and the drawing workability was also evaluated as "1."

In addition, the copper alloy sheet material of Comparative Example 3 had a large waviness (ear) on the edge of the drawn product due to the high total processing rate in the second cold rolling process [Process 8]. This is thought to be due to the development of texture due to the high total processing rate in the second cold rolling process [Process 8].

In addition, the copper alloy sheet material of Comparative Example 4 broke during the first drawing process because the Ni (nickel) content in the alloy composition was higher than the range specified in the present invention and the tensile strength was high.

In addition, the copper alloy sheet material of Comparative Example 5 had a lower Si (silicon) content in the alloy composition than the range of the present invention, and the tensile strength did not reach the acceptable level.

The copper alloy sheet material of Comparative Example 6 is an example in which the electrical conductivity does not reach the acceptable level.

In addition, the copper alloy sheet material of Comparative Example 7 had a higher Si (silicon) content in the alloy composition than the range of the present invention, and had a high tensile strength, so it broke during the first drawing process. Also, the electrical conductivity did not reach the acceptable level.

In addition, the copper alloy sheet material of Comparative Example 8 had a Ni (nickel) content in the alloy composition that was lower than the range of the present invention, and the tensile strength did not reach the acceptable level.

In addition, since the copper alloy sheet material of Comparative Example 10 did not undergo the intermediate annealing process [Process 4], the maximum value of the intensity of the inverse pole figure for the crystal plane facing the normal direction (ND) of the sheet surface exceeded 3.0, and the drawing workability was also evaluated as "1."

1 Drawn product 11 Bottom surface of drawn product 12 Side surface of drawn product 13 Edge of drawn product C Center of bottom surface of drawn product H ₀ , H ₄₅ , H ₉₀ , H ₁₃₅ , H ₁₈₀ , H ₂₂₅ , H ₂₇₀ , H ₃₁₅ Height from bottom surface to edge L ₁ to L ₈ Line segment drawn on bottom surface of drawn product X Rolling direction of copper alloy sheet material

Claims (5)

A copper alloy sheet material having an alloy composition containing Ni in a range of 1.00 mass% or more and 5.00 mass% or less, Si in a range of 0.20 mass% or more and 1.30 mass% or less, and the balance being Cu and unavoidable impurities,
The maximum value of the intensity of an inverse pole figure for a crystal plane facing the normal direction (ND) of the sheet surface obtained by crystal orientation analysis by an EBSD method, measured on the sheet surface of the copper alloy sheet material, is 3.0 or less;
The tensile strength is in the range of 500 MPa or more and 900 MPa or less, and
A copper alloy sheet material having a conductivity of 30% IACS or more. The copper alloy sheet material according to claim 1, wherein the ratio of azimuth angles at which the strength is 2.0 or less to all azimuth angles in the inverse pole figure is 50% or more. The copper alloy sheet material 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 ranging from 0.10 mass% to 1.00 mass%. A copper alloy sheet material for drawing, comprising the copper alloy sheet material according to any one of claims 1 to 3. A drawn product obtained by drawing the copper alloy sheet material according to any one of claims 1 to 3.

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