JP2019090097A - Copper alloy and manufacturing method therefor - Google Patents

Abstract

To provide a Cu-Zr alloy good in balance of strength and ductility.SOLUTION: The copper alloy contains Zr of 0.1 at.% to 5.0 at.%, has tensile strength of 620 MPa or more and breaking elongation of 3.5% or more and is linear or rod shape. The copper alloy may be obtained by a manufacturing method including a process for continuously extrusion processing the copper alloy with the above described composition to obtain an extruded material, and a process for continuously adding shearing strain to the extruded material so that cross section areas are same before and after processing, and pulverizing crystal particles until average crystal particle diameter calculated by SEM-EBSD analysis on a cross section parallel to an axis becomes 3.5 μm or less to obtain a pulverized material, and a process for wire drawing processing the pulverized material to obtain drawn material.SELECTED DRAWING: None

Description

  The present disclosure relates to a copper alloy and a method of manufacturing the same.

BACKGROUND ART In recent years, copper wires have become extremely thin and durability against disconnection is considered important, while conductor wires such as power transmission cables are required to have high conductivity. As a copper wire, for example, Zr is added to Cu, and by performing solution treatment, wire drawing, and aging treatment by electric heating, the tensile strength is 40 kgf / mm ² or more, elongation 5% or more, conductivity 80% IACS or more The following is proposed (Patent Document 1). In addition, the present inventors produced a thin Cu-0.2 at% Zr alloy using the vertical upper continuous casting method, and by combining the thermo-mechanical treatments performed in the middle of wire drawing, the crystal grains with a grain boundary spacing of 220 nm were obtained. It has been reported that a conductivity of 91.7% IACS and a tensile strength of 630 ± 10 MPa can be obtained (Non-patent Document 1).

  By the way, as a processing method of a copper alloy, continuous extrusion processing called a conform is known. Also, Equal-Channel Angular Pressing (ECAP) is known as a strong strain processing method for refining crystals. Then, it has been proposed to improve the balance between strength and ductility by applying conform and ECAP to dilute Cu-Mg alloy and further performing cold working (Non-Patent Document 2).

Japanese Patent Laid-Open No. 2000-160311

Copper and copper alloys, 56 (2017), 39-44 Journal of alloys and compounds, 582 (2014), 135-140

However, in Patent Document 1, the tensile strength is as low as 54.9 kgf / mm ² at the maximum, and a higher strength is required. In addition, in Non-Patent Document 1, the breaking elongation is about 1.1%, and there is a case where higher ductility is required, for example, when used for a cable to be stranded with plastic deformation. Furthermore, in the cited reference 2, a Cu-Si alloy known as a solid solution strengthening type alloy was examined, and a Cu-Zr alloy or the like known as a precipitation hardening type alloy was not examined.

  The present disclosure has been made in order to solve such problems, and it is a main object of the present invention to provide a Cu-Zr alloy having a good balance of strength and ductility.

  As a result of intensive studies to solve the problems described above, the present inventors conducted continuous extrusion processing on Cu-Zr alloy with a hypoeutectic composition so that the cross-sectional area before and after processing would be the same. It is found that the process of applying shear strain and wire drawing to the obtained material can achieve a good balance of strength and ductility, and complete the invention disclosed herein. It came to

That is, the copper alloy of the present disclosure is
0.1 at. % Or more 5.0 at. % Or less, tensile strength is 620 MPa or more, breaking elongation is 3.5% or more, and is linear or rod-like.

Alternatively, the copper alloy of the present disclosure is
0.1 at. % Or more 5.0 at. In a cross section parallel to the axis containing at most%, the average crystal grain size determined by SEM-EBSD analysis is 3.5 μm or less, and is linear or rod-like.

In addition, the method for producing a copper alloy of the present disclosure is
0.1 at. % Or more 5.0 at. Continuously extruding a copper alloy containing at most 10% to obtain an extruded material;
The extruded material is processed to continuously apply shear strain so that the cross-sectional area before and after processing is the same, and the average crystal grain size determined by SEM-EBSD analysis is 3.5 μm or less in the cross section parallel to the axis Obtaining fine particles by refining the crystal grains until
Is included.

  According to the copper alloy of the present disclosure and the method for manufacturing the same, a Cu-Zr alloy can provide a copper alloy having a good balance of strength and ductility.

FIG. The schematic diagram which shows a mode that the workpiece W passes through the channel | path 50 of the extrusion apparatus 10. As shown in FIG. FIG. 5 is a schematic view showing a state of ECAP using the extrusion device 10. The TEM-BF image of the longitudinal cross-section of the fine particle material of Example 2. FIG. The SEM-EBSD image of the longitudinal cross-section of the sample in each step in the middle of manufacture of Example 2. FIG. The SEM-Grain image of the longitudinal cross-section of the sample before ECAP of Example 2. FIG. The SEM-Grain image of the longitudinal cross-section of the sample at the end of 2 times of ECAP of Example 2. FIG. The SEM-Grain image of the longitudinal cross-section of the sample at the end of ECAP 3 times of Example 2. The SEM-Grain image of the longitudinal cross-section of the sample at the end of 4 times of ECAP of Example 2. Crystal grain size distribution of the sample before ECAP of Example 2. FIG. The grain size distribution of the sample at the end of 2 times of ECAP of Example 2. The grain size distribution of the sample at the end of ECAP 3 times in Example 2. The grain size distribution of the sample at the end of 4 times of ECAP of Example 2.

(Copper alloy of the first embodiment)
First, the copper alloy of the first embodiment of the present disclosure will be described. This copper alloy is linear or rod-like. In the present specification, it is not necessary to clearly distinguish between linear and rod-like, but for example, one having a diameter of 3 mm or more may be rod-like and one having a diameter less than 3 mm may be linear. This copper alloy has a Zr content of 0.1 at. % Or more 5.0 at. % Or less. With such a composition, the tensile strength, the elongation at break and the conductivity can be set to desired values because the amount of Zr is appropriate. The content of Zr is preferably a concentration exceeding the solid solution limit, for example, 0.12 at. % Or more is preferable, and 0.15 at. % Or more is more preferable. Also, 3.0 at. % Or less is preferable, and 1.0 at. % Or less is more preferable, 0.5 at. % Is more preferred. The copper alloy may be such that the balance is Cu and unavoidable impurities. As unavoidable impurities, for example, 0.007 wt. % Or less of Al, 0.007 wt. % Or less Si etc. are mentioned. Since this copper alloy has a hypoeutectic composition, a fine dendrite structure is obtained at the time of casting, and when wire drawing is performed, the α-Cu phase and the eutectic phase (a composite phase of Cu and a Cu-Zr compound) A nano-layered structure can be obtained, having high strength and high conductivity.

  This copper alloy has a tensile strength of 620 MPa or more and a breaking elongation of 3.5% or more. In this copper alloy, the tensile strength is preferably larger, preferably 630 MPa or more, more preferably 650 MPa or more, still more preferably 700 MPa or more, and still more preferably 750 MPa or more. The breaking elongation is preferably larger, preferably 3.6% or more, more preferably 4.0% or more, and still more preferably 5.0% or more. The conductivity is preferably higher, preferably 70% IACS or more, and more preferably 75% IACS or more. Among them, those satisfying tensile strength of 650 MPa or more, elongation at break of 5.0% or more, conductivity of 75% IACS or more, tensile strength of 700 MPa or more, elongation at break of 3.5% or more, conductivity of It is particularly preferable to satisfy 75% IACS or more.

  The cross-sectional shape of this copper alloy is not particularly limited, and may be circular, elliptical, polygonal or the like. The copper alloy may have, for example, a diameter of 0.01 mm or more and less than 3 mm, or may be 0.06 mm or more and 0.6 mm or less. When the cross section of the copper alloy is not circular, this diameter is taken as the average value of the diameter of the inscribed circle and the diameter of the circumscribed circle.

(Copper alloy of the second embodiment)
Next, the copper alloy of the second embodiment of the present disclosure will be described. The copper alloy can be made into the copper alloy of the first embodiment described above by subsequent wire drawing. This copper alloy has a Zr content of 0.1 at. % Or more 5.0 at. % Or less. The copper alloy may be such that the balance is Cu and unavoidable impurities. Such a composition is the same as the composition described in the copper alloy of the first embodiment, and thus the detailed description is omitted. In this copper alloy, in a cross section (longitudinal section) parallel to the axis, the average crystal grain size determined by SEM-EBSD analysis is 3.5 μm or less. In such a thing, tensile strength can be further raised in subsequent wire-drawing, and breaking elongation can be maintained at a high value. In the longitudinal section, the average crystal grain size is preferably 2 μm or less, more preferably 1.5 μm or less, and still more preferably 1 μm or less. Moreover, in this copper alloy, it is preferable that a peak appears in the range of 0.4 μm to 0.8 μm in the crystal grain size distribution in the crystal grain size distribution obtained by the SEM-EBSD analysis in the vertical cross section. It is more preferable that this peak appears in the range of 0.5 μm to 0.7 μm. In this copper alloy, the maximum crystal grain size is preferably 10 μm or less, more preferably 5 μm or less, and still more preferably 3 μm or less in the longitudinal cross section. Further, also in a cross section (horizontal cross section) perpendicular to the axis, it is preferable that the average grain size, the grain size distribution, and the maximum grain size are the same as in the vertical cross section. The average grain size, the grain size distribution, and the maximum grain size are values determined as follows. First, grain boundaries with a crystal misorientation of 2 ° or more are regarded as crystal grains by analysis using SEM-EBSD, and are represented as a grain image. The Grain image is obtained by randomly dividing each crystal grain. Next, the grain size of all crystal grains in the grain image is determined. The grain size is the diameter of a circle having the same area as the area of each crystal grain. Then, from the value of the maximum crystal grain size to 0 is divided into 20, and the central value D _n (n = 1, 2,..., 20) of each divided range is determined, and each divided range including the central value D _n The ratio A _n (n = 1, 2,..., 20) occupied by the total area of the crystal grains contained in. Furthermore, the average particle diameter D (μm) is derived from the equation of D = D ₁ × A ₁ + D ₂ × A ₂ +... + D ₂₀ × A ₂₀ . The crystal grain size distribution is obtained from a graph in which the value of D _n is taken along the horizontal axis and the value of A _n is taken along the vertical axis.

  In this copper alloy, the tensile strength is preferably larger, preferably 300 MPa or more, more preferably 325 MPa or more, and still more preferably 350 MPa or more. The breaking elongation is preferably larger, preferably 15% or more, more preferably 18% or more, and still more preferably 20% or more. The conductivity is preferably higher, preferably 80% IACS or more, and more preferably 85% IACS or more. Among them, those having a tensile strength of 350 MPa or more, an elongation of 20% or more, and a conductivity of 85% IACS or more are particularly preferable.

  The cross-sectional shape of this copper alloy is not particularly limited, and may be circular, elliptical, polygonal or the like. Further, for example, the copper alloy may have a diameter of 3 mm or more and 50 mm or less, or 5 mm or more and 15 mm or less. When the cross section of the copper alloy is not circular, this diameter is taken as the average value of the diameter of the inscribed circle and the diameter of the circumscribed circle.

(Method of manufacturing copper alloy)
Next, a method of manufacturing a copper alloy will be described. The manufacturing method may include (a) casting step, (b) continuous extrusion step, (c) shear strain application step, (d) wire drawing step, and (e) strain removing step. Below, each process is demonstrated.

(A) Casting step In this step, the raw material is melted and cast to a desired composition to obtain a cast material. The desired composition is 0.1 at. % Or more 5.0 at. % Or less. The copper alloy may be such that the balance is Cu and unavoidable impurities. Such a composition is the same as the composition described in the copper alloy of the first embodiment, and thus the detailed description is omitted. As a raw material, oxygen free copper and a Cu-Zr master alloy can be used, for example. The melting point of the Cu-Zr master alloy is lower than that of the Zr metal (2125 K), for example, the melting point of the Cu-50 mass% Zr master alloy is 1168 K, so the raw material can be melted at a relatively low temperature. The casting method is not particularly limited, but may be, for example, a vertical upward continuous casting method in which the molten metal is pulled upward to cast a casting. In the vertical upward continuous casting method, a large cooling rate can be obtained, so that the dendrite-like cast structure can be refined. This is preferable because it can be expected that a layered and fine structure can be obtained in the subsequent continuous extrusion process, and that processing resistance in the subsequent continuous extrusion process can be reduced. Moreover, it is preferable because it can be expected to reduce the risk of mixing of oxides and inclusions that are inevitably generated and floated.

(B) Continuous Extrusion Process In this process, the cast material is subjected to continuous extrusion to obtain an extruded material. For continuous extrusion, for example, a conform extrusion apparatus may be used. The schematic diagram of the extrusion apparatus 10 which is an example of a conform extrusion apparatus is shown in FIG. FIG. 2 is a schematic view showing how the workpiece W passes through the passage 50 of the extrusion device 10. The extrusion device 10 includes a main wheel 20, a sub wheel 30 disposed above the main wheel 20 in parallel with the main wheel 20, and a processing unit 40 provided on an outer peripheral side surface of the main wheel 20. . The main wheel 20 and the sub-wheel 30 are provided with drive units (not shown) that rotate the workpieces W (in this case, castings) in opposite directions so as to feed them toward the processing unit 40. A groove 22 extending in the circumferential direction is formed on the surface of the main wheel 20 so that the workpiece W can pass therethrough, and a protrusion 32 is formed on the surface of the sub wheel 30 so as to face the groove . The width, depth, and height of the groove 22 and the convex portion 32 are adjusted so that the material to be processed passes through the groove 22 with no problem. The processing unit 40 includes an abutment 42 for receiving the workpiece W delivered by the main wheel 20 and the sub wheel 30, and a die 44 having an outlet conforming to the shape of the target extrusion material. In the extrusion device 10, when the workpiece W is inserted into the passage 50 formed by the groove 22 and the convex portion 32, the workpiece W is along the groove 22 of the main wheel 20 by the rotation of the wheels 20, 30. It is sent to the processing unit 40. The workpiece W is blocked by the abutment 42 and disengaged from the main wheel 20. Frictional heat is generated between the workpiece W and the main wheel 20, and the workpiece W may be heated up to 500 ° C. Further, for example, it may be heated to 400 ° C. or more and 600 ° C. or less, or it may pass through without any heating. When the workpiece W abuts the abutment 42, the workpiece W is bent in a perpendicular direction along the abutment 42 toward the die 44 and extruded from the die hole of the die 44 while being formed. In this step, it is considered that shear strain is imparted to the workpiece W warmly or coldly depending on the above-described frictional heat by bending in the perpendicular direction at the processing portion 40 and reducing the diameter by the die 44 . In the processed portion 40, the workpiece W is bent in the perpendicular direction, but is not limited to 90 °, and is not less than 30 ° and not more than 150 °, preferably 45 ° or more and 135 ° or less, and more preferably 60 ° or more It may be bent in the range of 120 ° or less. Thus, shear strain can be applied. This angle may be adjusted by changing the attachment angle of the abutment 42, the position of the die, the angle of the die, or the like. 20% or more and 80% or less are preferable, and 30% or more and 70% or less are more preferable. Desired processing can be efficiently applied if the cross-sectional reduction rate at one time is 20% (equivalent strain 1.2) or more, and if it is 80% (equivalent strain 1.6) or less, the load on the processed portion 40 Is relatively small, so extrusion can be carried out smoothly. The delivery speed of the workpiece W by the main wheel 20 and the sub wheel 30 is preferably 1 m / min to 10 m / min, and more preferably 1 m / min to 5 m / min. The workpiece W extruded from the die 44 may be water-cooled.

(C) Shear strain applying step In this step, shear strain was applied continuously to the extruded material so that the cross-sectional area before and after processing was the same, and the cross section parallel to the axis was determined by SEM-EBSD analysis Fine grains are obtained by refining the crystal grains until the average crystal grain size is 3.5 μm or less. ECAP is mentioned as a processing method which gives shear strain continuously so that the cross-sectional area before and behind processing may become the same. ECAP may be performed, for example, using the extrusion device 10 described above. By using the extrusion device 10, shear strain can be continuously applied to the workpiece W 'more easily. The schematic diagram explaining the mode of ECAP which used the extrusion apparatus 10 for FIG. 3 is shown. In ECAP, as the main wheel 20 and the sub wheel 30, one having a groove 22 and a projection 32 matched to the dimensions of the workpiece W 'was used. Further, the processing unit 40 for continuous extrusion was replaced with the processing unit 45 for ECAP in which the shape of the abutment 47 was adjusted according to the shape of the groove 22 of the main wheel 20. In this processing, although the above-described extrusion apparatus 10 is used, since there is no diameter reduction by the die 44, processing is different from continuous extrusion processing. In the processing portion 40, shear strain is applied by bending the workpiece W 'in the perpendicular direction. Of course, the present invention is not limited to this combination of shapes, and may be a combination of shapes to which continuous shear strain is given. It is believed that shear strain is imparted in a warm or near-cold state by making the surface through continuous extrusion smooth and less susceptible to frictional resistance with the passage 50 having a smaller diameter for ECAP. In this step, it is preferable to carry out a process of continuously applying shear strain twice or more, more preferably three times or more, and still more preferably four times or more. The upper limit may be, for example, 10 times. When multiple ECAPs are performed, when performing the next ECAP, the workpiece W ′ may be rotated, for example, by 90 ° around the axis with respect to the immediately preceding ECAP, or may not be rotated. In this step, it is preferable to carry out processing to continuously apply shear strain until the average crystal grain size obtained by SEM-EBSD analysis in the longitudinal section becomes 2 μm or less, more preferably 1.5 μm or less, and 1 μm or less Is more preferred. Moreover, in this process, in the processing for continuously applying shear strain, a peak appears in the range of 0.4 μm to 0.8 μm in the crystal grain size distribution in the crystal grain size distribution determined by SEM-EBSD analysis in the longitudinal cross section. It is preferable to carry out the process up to 0.5 μm to 0.7 μm. Moreover, in this process, it is preferable to carry out the process of continuously applying shear strain until the maximum crystal grain size becomes 10 μm or less in the longitudinal cross section, more preferably 5 μm or less, and still more preferably 3 μm or less. Further, also in a cross section (horizontal cross section) perpendicular to the axis, it is preferable to obtain the same average crystal grain size, crystal grain size distribution, and maximum crystal grain size as in the vertical cross section. According to this process, the copper alloy of the present disclosure described above can be obtained. In the processing portion 45, the workpiece W is bent in the perpendicular direction, but is not limited to 90 °, and is not less than 30 ° but not more than 150 °, preferably 45 ° or more and 135 ° or less, more preferably 60 ° or more It may be bent in the range of 120 ° or less. Thus, shear strain can be applied. The delivery speed of the workpiece W ′ by the main wheel 20 and the sub wheel 30 is preferably 1 m / min to 10 m / min, more preferably 1 m / min to 5 m / min, and the same as in the continuous extrusion process. The workpiece W 'delivered from the die 44 may be water-cooled.

(D) Wire drawing process In this process, a fine grain material is subjected to wire drawing to obtain a wire drawn material. The wire drawing method is not particularly limited, and may be rolling, die wire drawing, or the like, and these may be combined. Such wire drawing is preferably performed cold. In this step, it is preferable to conduct drawing so that the cross-section reduction rate is 90% or more in the entire drawing, 95% or more is more preferable, and 99% or more is more preferable. According to this process, for example, a copper alloy having a tensile strength of 700 MPa or more, a breaking elongation of 3.5% or more, and a conductivity of 70% IACS or more can be obtained. Further, by performing (e) strain removing heat treatment thereafter, the breaking elongation can be increased, and for example, a copper alloy having a breaking elongation of 5% or more can be obtained.

(E) Strain removing step In this step, strain removing heat treatment is performed on the drawn wire. The conditions of the heat treatment for straining may be appropriately adjusted in accordance with the composition, diameter and the like of the drawn wire. For example, in the case of using a wire drawing material having a diameter of 0.01 mm or more and 1 mm or less, heat treatment is preferably performed in a temperature range of 300 ° C. or more and 700 ° C. or less, more preferably 400 ° C. or more and 600 ° C. or less, and 450 ° C. or more C. or less is more preferable. Moreover, it is preferable to perform this heat processing for 10 second or more and 10 hours or less, and 30 seconds or more and 2 hours or less are more preferable. According to this process, for example, a copper alloy having a tensile strength of 620 MPa or more, a breaking elongation of 5% or more, a conductivity of 75% IACS or more, a tensile strength of 700 MPa or more, a breaking elongation of 3.5% or more, A copper alloy having a conductivity of 75% IACS or more is obtained.

  According to the copper alloys described above and the method of manufacturing them, it is possible to provide a Cu-Zr alloy having a good balance of strength and ductility.

  It is needless to say that the present disclosure is not limited to the above-described embodiment at all, and may be implemented in various aspects within the technical scope of the present disclosure.

  For example, in the manufacturing method of the copper alloy mentioned above, although each process of (a)-(e) shall be performed, it is not limited to this. For example, the steps after the wire drawing step may be omitted. Even if these are omitted, the copper alloy of the second embodiment described above can be obtained, and thereafter, the copper alloy of the first embodiment can be obtained by performing wire drawing and a strain removing step as necessary. it can. Also, for example, a material having a desired composition may be separately prepared, and the casting step may be omitted. Also, for example, the strain removing step may be omitted. In this case, a copper alloy having higher tensile strength can be obtained although the elongation at break is slightly lower.

  Below, the example which manufactured the copper alloy of this indication is described as an Example. It is to be understood that the present disclosure is not limited to the following examples at all, and may be practiced in various forms within the technical scope of the present disclosure.

(Preparation of sample)
Example 1
(A) Casting step First, using Cu-0.19 at. Cu, using oxygen free copper and a cored wire in which a Cu-50 mass% Zr master alloy powder is enclosed. It melt | dissolved so that it might become% Zr alloy composition, and the cast material of diameter 14mm was produced by the vertical upper continuous casting method. The alloy composition was determined by inductively coupled plasma emission spectrometry using ICPS-8100 type manufactured by Shimadzu Corporation.

(B) Continuous extrusion process Using the above-described conform extrusion apparatus 10, a cast material having a diameter of 14 mm was continuously extruded so as to have a diameter of 10 mm, and was water-cooled to obtain an extruded material having a diameter of 10 mm (FIGS. reference). The extrusion device 10 includes a main wheel 20 having a diameter of 350 mm and a sub-wheel 30 having a diameter of 150 mm, and grooves 22 and protrusions 32 are formed on the surfaces of the wheels 20 and 30, respectively. A passage 50 having a diameter of 14 mm is formed by the portion 32. The delivery speed of the workpiece W by the main wheel 20 and the sub wheel 30 was 5 m / min. In the processing unit 40, the angle of the abutment 42 and the position / angle of the die 44 were adjusted so that the workpiece W was bent at a right angle, and the die 44 having a circular die hole with a diameter of 10 mm was used.

(C) Shear strain application step In the above-described extrusion device 10, the processing unit 40 was replaced with a processing unit 45 for ECAP (see FIG. 3). Using this extrusion device 10, ECAP was continuously applied four times to the extruded material having a diameter of 10 mm without changing its diameter to obtain a fine particle material having a diameter of 10 mm. In addition, when performing the next ECAP, the workpiece was rotated by 90 ° around the axis with respect to the previous ECAP. The delivery speed of the workpiece W by the main wheel 20 and the sub wheel 30 was 5 m / min. Water cooling was performed after ECAP.

(D) Wire drawing process Fine grained material with a diameter of 10 mm is further rolled to a diameter of 3 mm, die peeling is performed to a diameter of 2.7 mm, and wire drawing is then performed by die wire drawing to a diameter of 0.2 mm. I got a wire drawing material.

(E) Strain taking process A strain taking heat treatment at 500 ° C. for 48 seconds was performed on a 0.2 mm diameter drawn wire material to obtain strain coverage.

[Embodiments 2 and 3]
In the casting process, Cu-0.22 at. The sample of Example 2 was produced in the same manner as Example 1 except that the alloy composition of% Zr was adopted. In the casting process, Cu-0.27 at. The sample of Example 3 was produced in the same manner as Example 1 except that the alloy composition of% Zr was adopted.

Comparative Example 1
In the casting process, Cu 0.25 at. The sample of Comparative Example 1 was produced in the same manner as Example 1 except that the alloy composition of% Zr was adopted and the shear strain applying step and the strain-preventing heat treatment step were omitted.

(Confirmation of organization)
The structure of the cross section (longitudinal section) parallel to the axis of the sample was confirmed. TEM was used for tissue observation. Moreover, the crystal grain size was calculated | required by calculation based on the analysis result using SEM-EBSD. Specifically, first, grain boundaries with a crystal misorientation of 2 ° or more were regarded as crystal grains by analysis using SEM-EBSD, and expressed as a grain image. The Grain image is obtained by randomly dividing each crystal grain. Next, the grain size of all the crystal grains in the grain image was determined. The grain size was the diameter of a circle having the same area as the area of each crystal grain. Then, from the value of the maximum crystal grain size to 0 is divided into 20, and the central value D _n (n = 1, 2,..., 20) of each divided range is determined, and each divided range including the central value D _n The ratio A _n (n = 1, 2,..., 20) occupied by the total area of the crystal grains contained in. The derived average particle diameter D of the ([mu] m) from the equation _{D = D 1 × A 1 +} D 2 × A 2 + ··· + D 20 × A 20.

(Confirmation of mechanical characteristics)
AUTOGRAPH AG-X universal tester (JIS B 7721 grade 0.5) manufactured by Shimadzu Corporation was used to confirm the mechanical properties of the samples obtained up to the shear strain application step. As a test piece, what cut out the plate-like shouldered test piece of parallel part length 5 mm, width 3 mm, and thickness 0.4 mm from the fine grained rod material was used. The test was performed 3 times and the average value was calculated.

  An AG-I precision universal tensile tester (JIS B 7721 grade 0.5) manufactured by Shimadzu Corporation was used to confirm the mechanical properties of the samples obtained in the processes subsequent to the wire drawing process. The distance between the clamps was 100 mm. A mechanical test was conducted three times, and a mechanical property at the time of a test in which an elongation at break took an intermediate value was regarded as a mechanical property of each sample.

(Confirmation of conductivity)
The conductivity was determined by calculation from the electrical resistance measured using the four probe method.

(Experimental result)
Table 1 shows the experimental results of Examples 1 to 3 and Comparative Example 1. Further, in Table 2, a wire drawing material with a diameter of 0.2 mm was further drawn by die drawing to obtain a wire drawing material with a diameter of 0.08 mm, and this was subjected to heat treatment at 500 ° C. for 48 seconds for strain coverage The experimental result which did the same test about what is shown is shown. As experimental results, tensile strength (MPa), elongation at break (%), conductivity (% IACS) are shown. In Examples 1 to 3 in which ECAP was performed, both of the tensile strength and the elongation were improved as compared with Comparative Example 1 in which ECAP was not performed. Also, the conductivity showed a relatively high value. The reason why such an effect was obtained was presumed to be that ECAP provided a fine, uniform, equiaxed grain structure, and further, wire drawing processing provided a thin, uniform wire drawing structure. . Below, the sample in each stage in the middle of manufacture of Example 2 is mentioned as an example, and is demonstrated.

  The TEM-BF image of the longitudinal cross-section of the fine particle material of Example 2 is shown in FIG. Most of the grains in FIG. 4 are equiaxed grains, and the dislocation density of many grains is low. From this, it was inferred that recrystallization occurred during ECAP. Even in such a state where recrystallization has occurred, Cu-0.22 at. Fine grains of about 0.7 μm were observed in the% Zr material.

  The SEM-EBSD image of the longitudinal cross-section of the sample in each step in the middle of manufacture of Example 2 is shown in FIGS. 5A and 6 are before ECAP, FIGS. 5B and 7 are at the end of ECAP 2 times, FIGS. 5C and 8 are at the end of ECAP 3 times, and FIGS. 5D and 9 are at the end of ECAP 4 times. 10 to 13 show crystal grain size distributions obtained from the SEM-EBSD images of FIGS. 6 to 9, and Table 3 shows average crystal grain sizes obtained from the SEM-EBSD images of FIGS. From FIGS. 5 to 13 and Table 3, it was found that the crystal grain size was refined as the frequency of ECAP increased until the third ECAP, and stabilized at the fourth ECAP. In addition, it was found that the particle size variation at the end of ECAP four times was smaller than that at the end of ECAP three times, and the uniformity was high.

  The tensile strength of the fine-grained material at the end of the ECAP four times increased by 25 MPa as compared with the fine-grained material at the end of the two ECAP times. The breaking elongation also increased by 1.7%. However, the conductivity hardly changed even if ECAP was repeated. When the tensile strength is increased by the increase of the processing strain, the conductivity decreases due to the increase of the strain, but in the ECAP, the conductivity hardly changes. From this, it is inferred that the increase in tensile strength by ECAP is not due to an increase in processing strain, but is due to grain refinement.

  In the case of a 0.2 mm diameter drawn wire in which the fine grained material at the end of ECAP 4 times was subsequently subjected to wire drawing, although the tensile strength improved to 756 MPa, the elongation decreased to 3.6%. However, in the strain coverage where the strain was further heat-treated, the elongation was improved to 5.3% while having high tensile strength of 668 MPa. From the above, it was found that, by performing ECAP processing and then performing wire drawing and heat treatment for straining, for example, high strength with a tensile strength of 650 MPa or more and high ductility with a breaking elongation of 5% or more can be realized. In addition, it has been found that, when the degree of processing in wire drawing is further enhanced, for example, high strength with a tensile strength of 700 MPa or more and high ductility with a breaking elongation of 3.5% or more can be realized.

  From the above, dilute Cu-0.22 at. It has been found that the grain size of the intermediate wire diameter can be refined by preparing the% Zr alloy by continuous casting, adopting the ECAP-Conform process as part of intermediate processing, and performing continuous shear processing for mass production. It was also found that such new intermediate processing improves the ductility of the final wire after die drawing.

  The present disclosure is applicable to the field of using or producing copper alloys.

  DESCRIPTION OF SYMBOLS 10 Extrusion apparatus, 20 main wheels, 22 grooves, 30 sub wheels, 32 convex parts, 40 processed parts, 42 abutments, 44 dies, 45 processed parts, 47 abutments, 50 passages, W, W 'workpiece

Claims (16)

  0.1 at. % Or more 5.0 at. % Or less, a tensile strength of 620 MPa or more, an elongation at break of 3.5% or more, and a linear or rod-like copper alloy.   The copper alloy according to claim 1, wherein the conductivity is 70% IACS or more. The copper alloy according to claim 1 or 2, wherein any one or more of the following (1) to (3) are satisfied.
(1) The tensile strength is 650 MPa or more.
(2) Elongation at break is 5.0% or more.
(3) The conductivity is 75% IACS.   0.1 at. % Or more 5.0 at. Copper alloy containing a% or less and having a linear or rod-like shape and having an average crystal grain size of 3.5 μm or less determined by SEM-EBSD analysis in a cross section parallel to the axis. The copper alloy according to claim 4, satisfying any one or more of the following (1) to (3).
(1) The tensile strength is 300 MPa or more.
(2) Elongation at break is 15% or more.
(3) The conductivity is 80% IACS or more.   The copper alloy according to claim 4 or 5, wherein in a cross section parallel to the axis, the average crystal grain size determined by SEM-EBSD analysis is 1.5 μm or less.   The cross section parallel to an axis WHEREIN: In the crystal grain size distribution calculated | required by SEM-EBSD analysis, a crystal grain diameter shows a peak in the range of 0.4 micrometer or more and 0.8 micrometer or less. Copper alloy.   0.12 at. % Or more and 1.0 at. The copper alloy according to any one of claims 1 to 7, containing at most%. 0.1 at. % Or more 5.0 at. Continuously extruding a copper alloy containing at most 10% to obtain an extruded material;
The extruded material is processed to continuously apply shear strain so that the cross-sectional area before and after processing is the same, and the average crystal grain size determined by SEM-EBSD analysis is 3.5 μm or less in the cross section parallel to the axis Obtaining fine particles by refining the crystal grains until
A method of producing a copper alloy, including: A method of producing a copper alloy according to claim 9, wherein
The manufacturing method of the copper alloy including the process of carrying out the wire drawing of the said fine grain material, and obtaining a wire-drawing material. A method of producing a copper alloy according to claim 9 or 10, wherein
A manufacturing method of a copper alloy including the process of obtaining the distortion coverage by heat-treating the drawn wire at a temperature of 450 ° C. or more and 550 ° C. or less.   The manufacturing method of the copper alloy of any one of Claims 9-11 which performs the process which provides the said shear strain twice or more in the process of obtaining the said fine grain material.   The method for producing a copper alloy according to any one of claims 9 to 12, wherein, in the step of obtaining the fine particles, processing to apply the shear strain is performed four or more times.   14. The method according to any one of claims 9 to 13, wherein, in the step of obtaining the fine particles, crystal grains are refined in a cross section parallel to the axis until the average crystal grain size determined by SEM-EBSD analysis becomes 1.5 μm or less. The manufacturing method of the copper alloy of 1 item.   In the step of obtaining the fine particles, in the cross section parallel to the axis, in the crystal grain size distribution determined by SEM-EBSD analysis, the crystal grains are displayed until a peak appears in the range of 0.4 μm to 0.8 μm. The manufacturing method of the copper alloy of any one of Claims 9-14 which refine | miniaturizes.   In the step of obtaining the extruded material, the Zr content is 0.12 at. % Or more and 1.0 at. The method for producing a copper alloy according to any one of claims 9 to 15, wherein the copper alloy containing at most% is continuously extruded.