JP2012117152A - Soft-dilute-copper-alloy material, soft-dilute-copper-alloy wire, soft-dilute-copper-alloy sheet, soft-dilute-copper-alloy stranded wire, and cable using them - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide: a soft-dilute-copper-alloy material having high electrical conductivity and long bending life even in a soft copper material; a soft-dilute-copper-alloy wire, soft-dilute-copper-alloy sheet and soft-dilute-copper-alloy stranded wire; and also to provide a cable, coaxial cable and composite cable using them.SOLUTION: The soft-dilute-copper-alloy wire contains Ti of 4-55 ppm by mass and the balance of Cu, and is characterized in that the average crystal grain size is 20 μm or less in the surface layer up to a depth of at least 50 μm from the surface.

Description

  The present invention relates to a soft dilute copper alloy material, a soft dilute copper alloy wire, a soft dilute copper alloy plate, a soft dilute copper alloy stranded wire, and a cable using these, which have high conductivity and have a high bending life even in a soft material. Is.

  In recent science and technology, electricity is used in all parts such as electric power as a power source and electric signals, and wires such as cables and lead wires are used to transmit them. And as a material used for the conducting wire, a metal having high conductivity such as copper and silver is used, and in particular, a copper wire is very often used in consideration of cost.

  The copper and lump can be broadly divided into hard copper and soft copper according to the molecular arrangement. And the kind of copper which has a desired property according to the utilization purpose is used.

  Hard lead wires are often used as lead wires for electronic parts. For example, cables used in electronic devices such as medical devices, industrial robots, and notebook computers are combined with severe bending, twisting, and tension. Since it is used in an environment where external force is repeatedly applied, rigid hard copper wire is inaccurate and soft copper wire is used.

  Conductive wires used in such applications are required to have the opposite properties of good conductivity (high conductivity) and good bending properties. Development of a copper material that maintains its properties is underway (see Patent Document 1 and Patent Document 2).

  For example, the invention according to Patent Document 1 is an invention related to a conductor for a bending-resistant cable having good tensile strength, elongation, and electrical conductivity. Particularly, oxygen-free copper having a purity of 99.99 wt% or more is more than 99.99 wt% in purity. Bending Resistant Cable Conductor Formed with a Copper Alloy Containing 0.05 to 0.70 Mass% P and Purity 99.9 wt% or More in a Concentration Range of 0.0001 to 0.003 Mass% Have been described.

  In addition, the invention according to Patent Document 2 describes a bending-resistant copper alloy wire in which indium is 0.1 to 1.0 wt%, shelf is 0.01 to 0.1 wt%, and the balance is copper. .

JP 2002-363668 A Japanese Patent Laid-Open No. 9-256084

  However, the invention according to Patent Document 1 is an invention related to a hard copper wire to the last, a specific evaluation regarding bending resistance has not been made, and a study on a soft copper wire with higher bending resistance has not been made. Absent. Moreover, since there is much quantity of an additional element, electroconductivity will fall. The soft copper wire has not been fully studied. Moreover, although the invention which concerns on patent document 2 is invention regarding a soft copper wire, since the addition amount of an additional element is large similarly to the invention which concerns on patent document 1, electroconductivity will fall.

  On the other hand, it is conceivable to secure high conductivity by selecting a highly conductive copper material such as oxygen-free copper (OFC) as a copper material as a raw material.

  However, when this oxygen-free copper (OFC) is used as a raw material and it is used without adding other elements in order to maintain conductivity, oxygen-free copper can be obtained by increasing the degree of processing of the copper rough drawing wire. The idea of improving the bending resistance by making the crystal structure inside the wire fine may be effective, but in this case, it is suitable for use as a hard wire by work hardening by wire drawing, There is a problem that it cannot be applied to soft wires.

  Accordingly, an object of the present invention is to provide a soft dilute copper alloy material, a soft dilute copper alloy wire, a soft dilute copper alloy plate, a soft dilute copper alloy twisted wire having high conductivity and having a high bending life even in a soft copper material, and It is in providing the cable using these.

In order to achieve the above object, the invention of claim 1 is a soft dilute copper alloy wire containing 4 mass ppm to 55 mass ppm of Ti and the balance being copper, and the average grain size in the surface layer at least from the surface to a depth of 50 μm is 20 μm or less. A soft dilute copper alloy wire is provided.

  A second aspect of the present invention is the soft diluted copper alloy wire according to the first aspect, wherein the conductivity is 98% IACS or more.

  The invention according to claim 3 is the soft diluted copper alloy wire according to claim 1 or 2, wherein a plating layer is formed on a surface of the soft diluted copper alloy wire.

  A fourth aspect of the present invention is a soft dilute copper alloy stranded wire obtained by twisting a plurality of soft dilute copper alloy wires according to any one of the first to third aspects.

  According to a fifth aspect of the present invention, there is provided a cable characterized in that an insulating layer is provided around the soft diluted copper alloy wire or the soft diluted copper alloy stranded wire according to any one of the first to fourth aspects. is there.

  The invention of claim 6 is characterized in that, in a soft dilute copper alloy plate containing 4 massppm to 55 massppm of Ti and the balance being copper, the average grain size in the surface layer at least from the surface to a depth of 50 μm is 20 μm or less. It is a soft dilute copper alloy plate.

  A seventh aspect of the present invention is the soft diluted copper alloy plate according to the sixth aspect, wherein the conductivity is 98% IACS or more.

  The invention of claim 8 is characterized in that in the soft dilute copper alloy material containing 4 mass ppm to 55 mass ppm of Ti and the balance being copper, the average grain size in the surface layer at least from the surface to a depth of 50 μm is 20 μm or less. Soft dilute copper alloy material.

  A ninth aspect of the present invention is the soft diluted copper alloy material according to the eighth aspect, wherein the conductivity is 98% IACS or more.

  According to the present invention, a soft dilute copper alloy material, a soft dilute copper alloy wire, a soft dilute copper alloy plate, a soft dilute copper alloy twisted wire, and a soft dilute copper alloy wire having high conductivity and having a high bending life even in a soft copper material, and It exhibits an excellent effect that the used cable can be provided.

It is a figure which shows the SEM elephant of TiS particle | grains. It is a figure which shows the analysis result of FIG. Is a view showing an SEM image of the TiO ₂ particles. It is a figure which shows the analysis result of FIG. In this invention, it is a figure which shows the SEM image of Ti-O-S particle | grains. It is a figure which shows the analysis result of FIG. It is a figure which shows the outline of a bending fatigue test. The bending life was measured in the comparative material 13 using an oxygen-free copper wire and the implementation material 7 using a soft dilute copper alloy wire obtained by adding Ti to low oxygen copper after annealing at 400 ° C. for 1 hour. It is a graph. The bending life was measured in the comparative material 14 using an oxygen-free copper wire after annealing at 600 ° C. for 1 hour and the working material 8 using a soft dilute copper alloy wire obtained by adding Ti to low oxygen copper. It is a graph. 2 shows a photograph of a cross-sectional structure in the width direction of the working material 8. It shows a photograph of the cross-sectional structure in the width direction of the sample of the comparative material 14. It is drawing for demonstrating the measuring method of the average grain size in the surface layer of a sample. 2 shows a photograph of a cross-sectional structure in the width direction of the working material 9. It shows a photograph of the cross-sectional structure in the width direction of the sample of the comparative material 15. It is a figure which shows the relationship between the annealing temperature of the implementation material 9 and the comparison material 15, and elongation (%). It is a cross-sectional photograph of the implementation material 9 at an annealing temperature of 500 ° C. It is a cross-sectional photograph of the implementation material 9 at an annealing temperature of 700 ° C. 2 is a cross-sectional photograph of a comparative material 15.

  Hereinafter, a preferred embodiment of the present invention will be described in detail.

First of all, the object of the present invention is to satisfy 98% IACS (conductivity with an international standard copper resistance of 1.7241 × 10 ⁻⁸ Ωm as 100%), 100% IACS, and further 102% IACS. It is to obtain a soft dilute copper alloy material as a soft type copper material.

  A high-purity copper (4N) having an oxygen concentration of 1 to 2 mass ppm, and using a small continuous casting machine (small continuous casting machine) in a laboratory, a φ8 mm wire manufactured from a molten metal in which several mass ppm of titanium is added to the molten metal. When the softening temperature is measured with the rod φ2.6 mm (working degree 90%), it is 160 to 168 ° C., and the softening temperature is not lower than this. The conductivity is about 101.7% IACS. Therefore, it was found that even when Ti was added at a low oxygen concentration, the softening temperature could not be lowered, and the electrical conductivity of high purity copper (6N) was worse than 102.8% IACS.

  The reason for this is that sulfur is contained in several mass ppm or more as an unavoidable impurity during the production of molten metal, and sulphide such as TiS is not sufficiently formed between this sulfur and titanium, so that the softening temperature is not lowered. .

  In particular, in order to lower the semi-softening temperature, it is preferable to consider the following measures and combine the two effects.

(A) Increase the oxygen concentration of the material to an amount exceeding 2 mass ppm and add titanium. Thereby, it is considered that TiS, titanium oxide (TiO ₂ ) and Ti—O—S particles are first formed in the molten copper (see the SEM images in FIGS. 1 and 3 and the analysis results in FIGS. 2 and 4). ). In FIGS. 2, 4, and 6, Pt and Pd are vapor deposition elements for observation.

(B) Next, by setting the aging rolling temperature lower (880 to 550 ° C.) than the normal copper production conditions (950 to 600 ° C.), dislocations are introduced into the copper and S is likely to precipitate. Like that. As a result, precipitation of S on the dislocations or precipitation of S using titanium oxide (TiO ₂ ) as a nucleus forms Ti—O—S particles and the like as an example of molten copper (SEM image of FIG. 5 and FIG. 6 shows the analysis result). 1 to 6 are SEM observation and EDX analysis of a cross section of a φ8 mm copper wire (wire rod) having oxygen concentration, sulfur concentration, and Ti concentration shown in the third row from the top in Example 1 of Table 1. It has been evaluated. The observation conditions were an acceleration voltage of 15 KeV and an emission current of 10 μA.

  According to (a) and (b), sulfur in copper crystallizes and precipitates, and a copper wire rod that satisfies the softening temperature and conductivity after cold wire drawing can be obtained.

  Next, in this invention, (1)-(3) was restrict | limited as a restriction | limiting of manufacturing conditions with SCR continuous casting rolling equipment.

(1) About composition The reason why Ti was selected as the additive element is that these elements are active elements that are easily bonded to other elements, and can easily trap S because they are easily bonded to S. This is because the matrix) can be highly purified. One or more additive elements may be included. Also, other elements and impurities that do not adversely affect the properties of the alloy can be included in the alloy.

  Further, in the preferred embodiment described below, it is described that the oxygen content is more than 2 and not more than 30 mass ppm, but depending on the addition amount of the additive element and the S content, In the range having the property of, it is possible to include more than 2 and 400 mass ppm.

  When obtaining a soft copper material having an electrical conductivity of 98% IACS or higher, pure copper (base material) containing inevitable impurities is 3 to 12 mass ppm of sulfur, oxygen in an amount exceeding 2 mass ppm, and Ti to 4 to 4%. It is preferable to manufacture a wire rod (rough drawing wire) with a soft dilute copper alloy material containing 55 mass ppm. In this embodiment, so-called low oxygen copper (LOC) is targeted because it contains oxygen exceeding 2 mass ppm and not more than 30 mass ppm.

  Here, when obtaining a soft copper material having an electrical conductivity of 100% IACS or more, pure copper containing inevitable impurities contains 2 to 12 mass ppm of sulfur, oxygen in an amount exceeding 2 mass ppm, and Ti to 4 to 37 mass ppm. The wire rod is preferably made of a soft dilute copper alloy material.

  Furthermore, when obtaining a soft copper material having an electrical conductivity of 102% IACS or more, a soft dilute material containing 3-12 mass ppm of sulfur, oxygen exceeding 2 mass ppm, and 4-25 mass ppm of Ti in pure copper containing inevitable impurities. The wire rod is preferably made of a copper alloy material.

  Usually, in the industrial production of pure copper, sulfur is taken into copper when producing electrolytic copper, so it is difficult to make sulfur 3 mass ppm or less. In order to reduce the semi-softening temperature, it is preferable that the upper limit of the sulfur concentration of general-purpose electrolytic copper is 12 mass ppm.

  As described above, if the amount of oxygen to be controlled is small, the softening temperature is difficult to decrease, so the amount exceeds 2 mass ppm. Moreover, when there is too much oxygen, it becomes easy to produce a surface flaw in a hot rolling process, so it is preferable to make it 30 mass ppm or less.

(2) About dispersed substances It is desirable that the size of dispersed particles be small and distributed. The reason is that the size is small and the number is large because it functions as a sulfur deposition site.

Sulfur and titanium form compounds or aggregates in the form of TiO, TiO ₂ , TiS, and Ti—O—S, and the remaining Ti and S are present in the form of a solid solution. A soft dilute copper alloy material having a TiO size of 200 nm or less, TiO ₂ of 1000 nm or less, TiS of 200 nm or less, and Ti—O—S of 300 nm or less is distributed in the crystal grains. “Crystal grains” means the crystal structure of copper.

  However, since the size of the formed particles changes depending on the holding time of the molten copper during casting and the cooling condition, it is necessary to set casting conditions.

(3) About casting conditions By SCR continuous reading casting rolling, a wire rod is manufactured with an ingot rod working degree of 90% (30 mm) to 99.8% (5 mm). As an example, φ8 mm with a working degree of 99.3% A method of making a wire rod is used.

  (A) Molten copper temperature in a melting furnace shall be 1100 degreeC or more and 1320 degrees C or less. When the temperature of the molten copper is high, blowholes increase, scratches are generated, and the particle size tends to increase. The reason why the temperature is set to 1100 ° C. or higher is that copper is likely to solidify and the production is not stable, but the casting temperature is preferably as low as possible.

  (B) As for the hot rolling temperature, the temperature at the first rolling roll is 880 ° C. or lower, and the temperature at the final rolling roll is 550 ° C. or higher.

  Unlike normal pure copper production conditions, crystallization of sulfur in molten copper and precipitation of sulfur during hot rolling are the subject of the present invention, so in order to reduce the solid solubility limit that is the driving force. The molten copper temperature and the hot rolling temperature are preferably (a) and (b).

  The normal hot rolling temperature is such that the temperature at the first rolling roll is 950 ° C. or lower and the temperature at the final rolling roll is 600 ° C. or higher. In order to reduce the solid solution limit, Set the temperature at 980 ° C. or lower and the temperature at the final roll to 550 ° C. or higher.

  (C) A soft dilute copper alloy wire or a plate-like material having a conductivity of 98% IACS or more, 100% IACS, or 102% IACS or more can be obtained.

  In order to use it industrially, it is necessary to use 98% IACS or more with a soft copper wire of industrially used purity manufactured from electrolytic copper.

  The conductivity is about 101.7% IACS at the level of oxygen-free copper, and 102.8% IACS for high-purity copper (6N), so that the conductivity is as close as possible to high-purity copper (6N). Is desirable.

  After the base material copper was melted in the shaft furnace, it was controlled so as to be in a reduced state, that is, in a reducing gas (CO) atmosphere, the sulfur concentration, Ti concentration, and oxygen concentration of the constituent elements of the diluted alloy were controlled. A method of stably manufacturing a wire rod that is cast and rolled. Since the copper oxide is mixed and the particle size is large, the quality is lowered.

  Here, the reason for selecting Ti as the additive element is as follows.

  (A) Ti is easily bonded to sulfur in molten copper to form a compound.

  (B) It can be processed and handled more easily than other additive elements such as Zr.

  (C) It is less expensive than Nb or the like.

  (D) It is because it is easy to precipitate using an oxide as a nucleus.

As described above, the soft dilute copper alloy material of the present invention can be used as a soft copper wire because it can reduce the energy during molten solder plating (wire, plate, foil), enameled wire, soft pure copper, high conductivity copper, and annealing. Thus, it is possible to obtain a practical soft dilute copper alloy material having high productivity and excellent conductivity, softening temperature, and surface quality.
Further, a plating layer may be formed on the surface of the soft diluted copper alloy wire of the present invention. As the plating layer, for example, a layer mainly composed of tin, nickel, and silver is applicable, and so-called Pb-free plating may be used.
Moreover, it is also possible to use it as a soft dilute copper alloy twisted wire obtained by twisting a plurality of soft dilute copper alloy wires of the present invention.
Moreover, it can also be used as a cable in which an insulating layer is provided around the soft diluted copper alloy wire or the soft diluted copper alloy twisted wire of the present invention.
Further, a plurality of soft diluted copper alloy wires of the present invention are twisted together to form a central conductor, an insulator coating is formed on the outer periphery of the central conductor, and an outer conductor made of copper or a copper alloy is disposed on the outer periphery of the insulator coating, It can also be used as a coaxial cable provided with a jacket layer on its outer periphery.
Further, a plurality of coaxial cables can be arranged in the shield layer and used as a composite cable in which a sheath is provided on the outer periphery of the shield layer.
Applications of the soft dilute copper alloy wire of the present invention include, for example, wiring materials for consumer solar cells, conductors for enamel wires for motors, soft copper materials for high temperatures used at 200 to 700 ° C., conductors for power cables, and signal wires It can be used as a conductor, a molten solder plating material that does not require annealing, a wiring conductor for FPC, a copper material excellent in heat conduction, and a high-purity copper replacement material. The shape is not particularly limited, and may be a conductor having a round cross section, a rod-shaped conductor, or a flat conductor.
In addition, the use of the soft dilute copper alloy plate of the present invention can be adapted to a wide range of uses such as copper plates used for heat sinks, deformed copper materials used for lead frames, copper foils used for wiring boards, etc. It is.

  In the above-described embodiment, the wire rod is manufactured by the SCR continuous casting rolling method, and the soft material is manufactured by hot rolling. However, the present invention is not limited to the twin roll continuous casting rolling method or the proper perch. You may make it manufacture by a type | formula continuous casting rolling method.

  Table 1 relates to experimental conditions and results.

  First, as an experimental material, φ8 mm copper wire (wire rod) with a processing degree of 99.3% was prepared with the oxygen concentration, sulfur concentration, and Ti concentration shown in Table 1, respectively. The φ8 mm copper wire is hot-rolled by SCR continuous casting and rolling. Ti flows the molten copper melted in the shaft furnace into the reed in the reducing gas atmosphere, guides the molten copper flowing in the reed to the casting pot of the same reducing gas atmosphere, and after adding Ti in this casting pot, An ingot rod was made with a mold formed between the cast ring and the endless belt through the nozzle. This ingot rod is hot-rolled to produce a φ8 mm copper wire. The experimental material was cold-drawn, the semi-softening temperature and conductivity at a size of φ2.6 mm were measured, and the dispersed particle size at a copper wire of φ8 mm was evaluated.

  The oxygen concentration was measured with an oxygen analyzer (Leco ™ oxygen analyzer). Each concentration of sulfur and Ti is the result of analysis with an ICP emission spectroscopic analyzer.

  The measurement of the semi-softening temperature in the size of φ2.6 mm was obtained from the result of quenching in water after holding each temperature at 400 ° C. or less for 1 hour and conducting a tensile test. It calculated | required using the result of the tensile test at room temperature, and the result of the tensile test of the soft copper wire which carried out the oil bath heat treatment for 1 hour at 400 degreeC. The temperature corresponding to the strength showing the value obtained by adding the tensile strengths of these two tensile tests and dividing by 2 was defined as the semi-softening temperature.

  In Table 1, the implementation material 10 is the result of trial production of a copper wire having a diameter of 8 mm in an Ar atmosphere in a laboratory, and Ti is added to 0 to 18 mass ppm of molten copper.

  The industrially requested electrical conductivity was 98% IACS or higher and satisfied, and the overall evaluation was good.

  Therefore, a Ø8 mm copper wire (wire rod) was prototyped by adjusting the oxygen concentration to 7 to 8 mass ppm by the SCR continuous casting and rolling method.

  The execution material 11 was a material having a small Ti concentration (0.2 mass ppm) among the prototypes manufactured by the SCR continuous casting and rolling method, the electrical conductivity was 102% IACS or more, and the overall evaluation was good.

  About execution material 1, oxygen concentration and sulfur are the results of trial materials with almost constant (7-8 mass ppm, 5 mass ppm) and different Ti concentrations (4-55 massppm).

  In this Ti concentration range of 4 to 55 mass ppm, the electrical conductivity is 98% IACS or higher and 102% IACS or higher, which is favorable. And the surface of the wire rod is also clean, and all are satisfied as product performance (overall evaluation ○).

  Here, the case where the electrical conductivity satisfies 100% IACS or higher is when the Ti concentration is 4 to 37 mass ppm, and the case where the electrical conductivity satisfies 102% IACS or higher is when the Ti concentration is 4 to 25 mass ppm. When the Ti concentration was 13 mass ppm, the maximum conductivity was 102.4% IACS, and the conductivity was slightly lower in the vicinity of this concentration. This is because when Ti is 13 mass ppm, the sulfur content in copper is captured as a compound, thereby showing conductivity close to that of high-purity copper (6N).

  Therefore, both the semi-softening temperature and the conductivity can be satisfied by increasing the oxygen concentration and adding Ti.

  Comparative material 3 is a prototype material having a Ti concentration as high as 60 mass ppm. This comparative material 3 does not satisfy the demand for electrical conductivity.

  Next, Example Material 2 is a prototype material in which the sulfur concentration is set to 5 mass ppm, the Ti concentration is set to 13 to 10 mass ppm, and the oxygen concentration is changed to examine the influence of the oxygen concentration.

  With respect to the oxygen concentration, prototype materials having greatly different concentrations from 2 mass ppm to 30 mass ppm or less were used. However, when oxygen is less than 2 mass ppm, production is difficult and stable production cannot be performed, so the overall evaluation is Δ. It was also found that even when the oxygen concentration was increased to 30 mass ppm, both the semi-softening temperature and the conductivity were satisfied.

  Moreover, as shown in the implementation material 12, it was found that the conductivity was satisfied even when the oxygen was 40 mass ppm.

  Therefore, by setting the oxygen concentration to an amount exceeding 2 mass ppm, it is possible to satisfy the characteristics of conductivity 102% IACS or more.

  Next, the implementation material 3 is an example of a prototype material in which the oxygen concentration and the Ti concentration are relatively close to each other, and the Ti concentration is changed to 4 to 20 mass ppm. In this implementation material 3, the prototype material with less sulfur than 2 mass ppm could not be realized from the raw material side, but the conductivity can be satisfied by controlling the concentrations of Ti and sulfur.

  When the sulfur concentration of the comparative material 5 was 18 mass ppm and the Ti concentration was 13 mass ppm, the required characteristics were satisfied.

  From the above, it was found that when the sulfur concentration was 2 to 12 mass ppm, the characteristics of conductivity 102% IACS or higher were also satisfied.

  Moreover, although the examination result using high purity copper (6N) as the comparative material 6 was shown, electrical conductivity was 102.8% IACS.

  Table 2 shows the molten copper temperature and rolling temperature as the production conditions.

  The execution material 4 shows the result of trial manufacture of a φ8 mm wire rod at a molten copper temperature of 1200 to 1320 ° C. and a lower rolling temperature of 880 to 550 ° C. About this implementation material 4, electrical conductivity was also favorable and comprehensive evaluation was (circle).

[Soft characteristics of soft dilute copper alloy wire]
Table 3 shows a sample of the comparative material 11 using an oxygen-free copper wire and the embodiment material 5 using a soft dilute copper alloy wire containing 13 mass ppm Ti in low-oxygen copper, and annealing at different annealing temperatures for 1 hour. It is the table | surface which verified Vickers hardness (Hv) of what gave.
The implementation material 5 was the same as the alloy composition described in the implementation material 1 of Table 1. As a sample, a 2.6 mm diameter sample was used. According to this table, when the annealing temperature is 400 ° C., the Vickers hardness (Hv) of the comparative material 11 and the execution material 5 is equivalent, and even when the annealing temperature is 600 ° C., the equivalent Vickers hardness (Hv) is shown. Yes. From this, the soft dilute copper alloy wire of the present invention has sufficient soft properties and has excellent soft properties even in the region where the annealing temperature exceeds 400 ° C., even when compared with the oxygen-free copper wire. I understand that.

[Study on yield strength and bending life of soft diluted copper alloy wire]
Table 4 shows a comparison material 12 using an oxygen-free copper wire and an embodiment material 6 using a soft dilute copper alloy wire containing 13 mass ppm Ti in low-oxygen copper, and annealed for 1 hour at different annealing temperatures. It is the table | surface which verified the transition of 0.2% proof stress value of what was given. As a sample, a 2.6 mm diameter sample was used.
According to this table, when the annealing temperature is 400 ° C., the 0.2% proof stress value of the comparative material 12 and the execution material 6 is the same level. It can be seen that the yield strength is 2%.

Next, the soft dilute copper alloy wire according to the present invention is required to have a high flex life, but the comparative material 13 using an oxygen-free copper wire and the soft dilute copper alloy wire obtained by adding Ti to low oxygen copper are used. The result of measuring the bending life of the used material 7 is shown in FIG. Here, as a sample, a 0.26 mm-diameter wire annealed at an annealing temperature of 400 ° C. for 1 hour is used, the comparative material 13 has the same component composition as the comparative material 11, and the implementation material 7 is also used. The component composition similar to that of Example Material 5 was used.
Here, the bending life was measured by a bending fatigue test. The bending fatigue test is a test in which a load is applied and repeated bending strain of tension and compression is applied to the sample surface. The bending fatigue test is shown in FIG. The sample is set between bending jigs (denoted as rings in the figure) as shown in (A), and the jig is rotated by 90 degrees and bent as shown in (B) while a load is applied. By this operation, a compressive strain is applied to the surface of the wire rod in contact with the bending jig, and a tensile strain is applied to the opposite surface correspondingly. Thereafter, the state returns to the state (A) again. Next, it is rotated 90 degrees in the direction opposite to the direction shown in FIG. Also in this case, a compressive strain is applied to the surface of the wire rod in contact with the bending jig, and a tensile strain is applied to the surface on the opposite side, corresponding to the state (C). And it returns to the first state (A) from (C). The time required for one cycle of bending fatigue (A), (B), (A), (C), and (A) is 4 seconds. The surface bending strain can be obtained by the following equation.
Surface bending strain (%) = r / (R + r) × 100 (%), R: wire bending radius (30 mm), r = wire radius According to the experimental data of FIG. The bending life was higher than that of the material 13.
Moreover, the result of having measured the bending life in the comparative material 14 using an oxygen free copper wire and the implementation material 8 using the soft dilute copper alloy wire which added Ti to low oxygen copper is shown in FIG. Here, a sample obtained by subjecting a 0.26 mm diameter wire to an annealing temperature of 600 ° C. for 1 hour is used, the comparative material 14 has the same composition as the comparative material 11, and the implementation material 8 is also used. The component composition similar to that of Example Material 5 was used. The measuring method of the bending life was performed under the same conditions as the measuring method of FIG. Also in this case, the working material 8 according to the present invention showed a higher bending life than the comparative material 14.

[Examination of crystal structure of soft dilute copper alloy wire]
10 shows a photograph of the cross-sectional structure in the width direction of the sample of the embodiment material 8, and FIG. 11 shows a photograph of the cross-sectional structure in the width direction of the comparative material 14. FIG. 11 shows the crystal structure of the comparative material 14, and FIG. 10 shows the crystal structure of the working material 8. From this, it can be seen that the crystal structure of the comparative material 14 has uniform crystal grains of uniform size as a whole from the surface to the center. On the other hand, the crystal structure of the embodiment material 8 has a sparse crystal grain size as a whole, and it should be noted that the crystal grain size in the thin layer formed near the surface in the cross-sectional direction of the sample is internal. It is extremely small compared to the crystal grain size.
The inventors believe that the fine crystal grain layer that appears on the surface layer, which is not formed in the comparative material 14, contributes to the improvement of the bending characteristics of the working material 8.
This is understood that, if the annealing treatment is normally performed at an annealing temperature of 600 ° C. for 1 hour, crystal grains uniformly coarsened by recrystallization are formed as in the comparative material 14. However, in the case of the present invention, the fine crystal grain layer still remains on the surface layer even when the annealing treatment is performed at an annealing temperature of 600 ° C. for 1 hour. It is considered that a soft dilute copper alloy material having a good thickness was obtained.
And based on the cross-sectional photograph of the crystal structure shown to FIG. 10 and FIG. 11, the average crystal grain size in the surface layer of the sample of the implementation material 8 and the comparison material 14 was measured. Here, as shown in FIG. 12, the measurement method of the average crystal grain size in the surface layer is 1 mm in length from the surface of the cross section in the width direction of 0.26 mm diameter to the depth of 50 μm at 10 μm intervals in the depth direction. A value obtained by averaging the actually measured values of the crystal grain sizes in the range on the line was defined as the average crystal grain size in the surface layer.
As a result of the measurement, the average crystal grain size in the surface layer of the comparative material 14 was 50 μm, whereas the average crystal grain size in the surface layer of the example material 8 was greatly different in that it was 10 μm. It is considered that the growth of cracks in the bending fatigue test was suppressed by the fine average grain size of the surface layer, and the bending fatigue life was extended (if the grain size is large, cracks propagate along the grain boundaries). If the crystal grain size is small, the direction of crack growth changes, so the growth is suppressed). As described above, this is considered to have caused a great difference in the bending characteristics between the comparative material and the working material.
In addition, the average crystal grain size in the surface layer of the embodiment material 6 and the comparison material 12 having a diameter of 2.6 mm is 10 mm in length at a depth of 50 μm in the depth direction from the surface of the cross section in the width direction of 2.6 mm diameter. The grain size in the range was measured.
As a result of the measurement, the average crystal grain size in the surface layer of the comparative material 12 was 100 μm, whereas the average crystal grain size in the surface layer of the example material 6 was 20 μm.
As an effect of the present invention, the upper limit value of the average grain size of the surface layer is preferably 20 μm or less, and a value of 5 μm or more is assumed from the manufacturing limit value.

[Examination of crystal structure of soft dilute copper alloy material]
FIG. 13 shows a photograph of the cross-sectional structure in the width direction of the sample of the embodiment material 9, and FIG. 14 shows a photograph of the cross-sectional structure in the width direction of the comparative material 15. FIG. 13 shows the crystal structure of Example Material 9, and FIG.

  The implementation material 9 is a 0.26 mm diameter wire having the highest conductivity of the third softest material from the top of the implementation material 1 shown in Table 1. This execution material 9 is produced through an annealing treatment at an annealing temperature of 400 ° C. for 1 hour.

  The comparative material 15 is a 0.26 mm diameter wire made of oxygen-free copper (OFC). The comparative material 15 is manufactured through an annealing process at an annealing temperature of 400 ° C. for 1 hour. Table 5 shows the electrical conductivity of Example Material 9 and Comparative Material 15.

  As shown in FIG. 13 and FIG. 14, it can be seen that the crystal structure of the comparative material 15 has uniform crystal grains having the same overall size from the surface portion to the center portion. On the other hand, the crystal structure of the embodiment material 9 has a difference in crystal grain size between the surface layer and the inside, and the inside crystal grain size is extremely larger than the crystal grain size in the surface layer.

For example, the execution material 9 captures S in the copper of the conductor processed so as to have φ2.6 mm and φ0.26 mm in the form of Ti—S and Ti—O—S. The oxygen contained in the copper (O), for example, as TiO _2, is present in the form of TixOy, the crystal grains are precipitated in the grain boundaries.

  For this reason, when copper is annealed and the crystal structure is recrystallized, the recrystallized material 9 tends to proceed recrystallized, and the internal crystal grains grow greatly. For this reason, compared with the comparative material 15, the implementation material 9 progresses with less obstruction of the flow of electrons when a current is passed, and the electrical resistance is reduced. Therefore, the implementation material 9 has a higher conductivity (% IACS) than the comparison material 15.

  Based on the above results, the product using the embodiment material 9 is soft, has improved conductivity, and improved bending characteristics. In the conventional conductor, a high-temperature annealing process is required to recrystallize the crystal structure to the size of the embodiment material 9. However, if the annealing temperature is too high, S will be re-dissolved. Further, the conventional conductor has a problem that when it is recrystallized, it becomes soft and the bending property is lowered. In the embodiment material 9 described above, since it can be recrystallized without being twinned when annealed, the internal crystal grains become large and soft, but the surface layer is bent because fine crystals remain. There is a characteristic that the characteristics do not deteriorate.

[Relationship between elongation characteristics and crystal structure of soft dilute copper alloy wire]
FIG. 15 shows, as a sample, a comparative material 15 using an oxygen-free copper wire having a diameter of 2.6 mm and an embodiment material 9 using a soft dilute copper alloy wire containing 13 mass ppm of Ti in low-oxygen copper having a diameter of 2.6 mm. It is the graph which verified the transition of the value of elongation (%) of what annealed for 1 hour at different annealing temperature. A circle symbol shown in FIG. 15 indicates the implementation material 9, and a square symbol indicates the comparison material 15.
According to this table, it can be seen that the embodiment material 9 exhibits excellent elongation characteristics over a wide range from about 130 ° C. to 900 ° C., compared to the comparative material 15, with the annealing temperature exceeding 100 ° C.
Further, FIG. 16 shows a cross-sectional photograph of the copper wire of the embodiment material 9 at an annealing temperature of 500 ° C. FIG. 16 shows that a fine crystal structure is formed in the entire cross section of the copper wire, and this fine crystal structure seems to contribute to the elongation characteristics. On the other hand, the cross-sectional structure of the comparative material 15 at the annealing temperature of 500 ° C. has undergone secondary recrystallization, and the crystal grains in the cross-sectional structure are coarser than the crystal structure of FIG. Is thought to have been reduced.
Further, FIG. 17 shows a cross-sectional photograph of the copper wire of Example Material 9 at an annealing temperature of 700 ° C. It turns out that the crystal grain size of the surface layer in the cross section of a copper wire is very small compared with the crystal grain size inside. Although the internal crystal structure is undergoing secondary recrystallization, a fine crystal grain layer in the outer layer remains. Although the inner crystal structure grows greatly in the execution material 9, since the fine crystal layer remains on the surface layer, it seems that the elongation characteristics are maintained.
On the other hand, in the cross-sectional structure of the comparative material 15 similarly at an annealing temperature of 700 ° C. shown in FIG. 18, crystal grains having substantially the same size are arranged uniformly from the surface to the center. Since the crystallization is progressing, it is considered that the elongation property of the comparative material 15 in the high temperature region of 600 ° C. or higher is lower than that of the embodiment material 9.
As described above, the embodiment material 9 is superior to the comparison material 15 in terms of elongation characteristics, and therefore, it is excellent in handling property when producing a stranded wire using this conductor, excellent in bending resistance characteristics, and easy to bend. Also in this point, there is an advantage that the cable arrangement becomes easy.

  As mentioned above, although embodiment of this invention and its modification were demonstrated, embodiment and modification which were described above do not limit the invention which concerns on a claim. In addition, it should be noted that not all combinations of features described in the embodiments and the modifications are necessarily essential to the means for solving the problems of the invention.

Claims (9)

  A soft dilute copper alloy wire containing 4 massppm to 55 massppm of Ti and having a balance of copper, wherein the average crystal grain size in a surface layer at least from the surface to a depth of 50 m is 20 m or less.   The soft diluted copper alloy wire according to claim 1, wherein the conductivity is 98% IACS or more.   The soft diluted copper alloy wire according to claim 1 or 2, wherein a plating layer is formed on a surface of the soft diluted copper alloy wire.   A soft dilute copper alloy twisted wire comprising a plurality of soft dilute copper alloy wires according to any one of claims 1 to 3.   A cable comprising an insulating layer around the soft dilute copper alloy wire or soft dilute copper alloy twisted wire according to any one of claims 1 to 4. A soft dilute copper alloy plate containing 4 mass ppm to 55 massppm of Ti, the balance being copper, and an average crystal grain size in a surface layer at least from the surface to a depth of 50 μm is 20 μm or less.   7. The soft diluted copper alloy plate according to claim 6, wherein the electrical conductivity is 98% IACS or more. A soft dilute copper alloy material containing 4 massppm to 55 massppm of Ti and having a balance of copper, wherein the average crystal grain size in a surface layer at least from the surface to a depth of 50 m is 20 m or less.   The soft diluted copper alloy material according to claim 8, wherein the electrical conductivity is 98% IACS or more.