JP2005288519A - Electrode material and its production method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To increase the mechanical properties, heat resistance and high temperature yield stress of a copper alloy material for welding, and to improve its continuous spotting properties (electrode life) as an electrode material. <P>SOLUTION: An alloy stock expressed by general formula of Cu<SB>bal.</SB>Cr<SB>a</SB>Zr<SB>b</SB>X<SB>c</SB>(wherein, X is at least one kind of element selected from Fe, P, Co, Si and Mn; a, b and c satisfy 0.4 wt%≤a≤1.5wt%, 0.02 wt%≤b≤0.1 wt%, and 0≤Fe+P+[Co×0.75]+[Si×0.6]+[Mn×0.35]<0.015 wt%, respectively and the balance Cu with inevitable impurities) is subjected to extrusion at 300 to 600°C at an extrusion ratio of ≥4 by an extrusion method or an equal-channel angular extrusion method as shown in Figure, thus the electrode material having a structure where fine grains with a mean grain size of ≤50 nm are precipitated into a structure composed of fibrous crystal grains with a minor axis length of ≤10 μm consisting of subcrystal grains with a mean grain size of ≤3 μm is obtained. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an electrode material used when welding a material to be welded made of aluminum, magnesium, iron and alloys thereof, and further, a metal plating material thereof, and a manufacturing method thereof.

Conventionally, chromium, copper (Cu—Cr), alumina-dispersed copper (Al ₂ O ₃ ) are used as electrode materials used when welding a material to be welded made of aluminum, magnesium, iron, and alloys thereof, or metal plating materials thereof. An electrode material made of (dispersed copper) is used.

  For example, Patent Document 1 has a defect that a welding electrode material made of a Cu—Cr alloy is manufactured at a high temperature of about 1000 ° C., so that crystal grains in the alloy become coarse and wear resistance and heat resistance become low. However, it is described that by adding 0.01 to 0.2% by weight of boron to this Cu—Cr alloy, crystal grains of the alloy are refined to improve heat resistance and high temperature hardness.

  Patent Document 2 describes that an alloy having high conductivity and high strength can be obtained by adding a limited amount of Cr and Zr in copper. Specifically, Cu-0.01-2.0 wt% Cr alloy, Cu-0.005-1.0 wt% Zr alloy, Cu-0.01-2.0 wt% Cr-0.005-1.0 wt% Zr alloys and the like are mentioned.

  In Patent Document 3, the electrode composition is made of an alloy composition of welding electrode material of Cr 0.4 to 1.0 wt%, Sn 0.05 to 0.2 wt%, and the balance made of copper containing inevitable impurities. It is described that the life of the tip is improved by reducing deformation and wear of the tip.

  In Patent Document 4, the composition of the welding electrode material is an alloy composition made of 0.05 to 1.0% by weight of Zr, 3 to 20% by weight of Cr, and the balance Cu, so that the conductivity is increased and the wear resistance is improved. It is described to improve and increase the number of spot welding spots.

  However, an electrode material made of chromium copper has a problem that the electrical conductivity and thermal conductivity are low because of the large amount of Cr dissolved, and the repeated fatigue strength is low because the crystal grain size is as large as several tens of μm. When used as an electrode material, the electrode tip diameter expands with a small number of spots and the welding current density decreases, resulting in low continuous spotting, and low conductivity and thermal conductivity. There is a problem that the number of welding hit points is low.

  In addition, the electrode material made of alumina-dispersed copper has low yield stress at high temperatures, the electrode tip diameter increases with a small number of spots, and the welding current density decreases. Since the conductivity is low, there is a problem that it is easy to alloy with the material to be welded and the number of welding hit points is low.

Japanese Patent Publication No.56-31196 JP 59-193233 A Japanese Patent Application Laid-Open No. 62-3885 JP-A-6-73473

Therefore, the present invention has been made to solve the above-described problems, and finely precipitate particles containing atoms having a low diffusion rate in a structure composed of fibrous crystal grains composed of sub-crystal grains. In addition to improving mechanical properties, heat resistance, high-temperature yield stress, and continuous spotting properties (electrode life) as electrode materials, it also improves conductivity by promoting precipitation of fine precipitates, and is a material to be welded as an electrode material. It is an object of the present invention to provide an electrode material capable of suppressing alloying and improving the number of welding points (welding resistance) and a method for producing the same.
In addition, the present invention improves toughness by refining crystal grains, further improves conductivity by promoting precipitation of fine precipitates, and provides continuous spotability (electrode life) as an electrode material and welding hits. An object is to provide an electrode material capable of improving the score (welding resistance) and a method for producing the same.

The configuration of the present invention is as described below.
(1) General formula: Cu _bal. Cr _a Zr _b X _c (where X is at least one element selected from Fe, P, Co, Si, Mn, and a, b, c are each 0 .4 wt% ≦ a ≦ 1.5 wt%, 0.02 wt% ≦ b ≦ 0.1 wt%, 0 ≦ Fe + P + [Co × 0.75] + [Si × 0.6] + [Mn × 0.35] < The minor axis length is composed of a sub-crystal grain having an average grain size of 3 μm or less. The electrode material according to (1), wherein the electrode material has a structure in which fine particles having an average crystal particle diameter of 50 nm or less are precipitated in a structure composed of fibrous crystal grains having a diameter of 10 μm or less.
(2) General formula: Cu _bal. Cr _a Zr _b X _c (where X is at least one element selected from Fe, P, Co, Si, Mn, and a, b, c are each 0 .4 wt% ≦ a ≦ 1.5 wt%, 0.02 wt% ≦ b ≦ 0.1 wt%, 0 ≦ Fe + P + [Co × 0.75] + [Si × 0.6] + [Mn × 0.35] < In which the balance is 0.015 wt% and the balance is Cu containing inevitable impurities), and the structure of the composition is in a structure composed of equiaxed crystal grains having an average crystal grain size of 3 μm or less. An electrode material having a structure in which fine particles having an average crystal grain size of 50 nm or less are precipitated.

(3) General formula: Cu _bal. Cr _a Zr _b X _c (where X is at least one element selected from Fe, P, Co, Si, Mn, and a, b, c are each 0 .4 wt% ≦ a ≦ 1.5 wt%, 0.02 wt% ≦ b ≦ 0.1 wt%, 0.001 ≦ Fe + P + [Co × 0.75] + [Si × 0.6] + [Mn × 0.35 The electrode material according to the above (1) or (2), wherein the electrode material has a composition represented by <0.015 wt% and the balance is Cu containing inevitable impurities].
(4) The electrode material according to any one of (1) to (3) above, wherein the precipitation dispersion state of the fine particles is an average interparticle distance of 200 nm or less.
(5) The electrode material according to (1) to (4) above, wherein the fine particles are at least one selected from Cr, Cu ₃ Zr, and Cu ₉ Zr ₂ .

(6) General formula: Cu _bal. Cr _a Zr _b X _c (where X is at least one element selected from Fe, P, Co, Si, Mn, and a, b, c are each 0 .4 wt% ≦ a ≦ 1.5 wt%, 0.02 wt% ≦ b ≦ 0.1 wt%, 0 ≦ Fe + P + [Co × 0.75] + [Si × 0.6] + [Mn × 0.35] < A method for producing an electrode material, comprising: extruding a Cu-based alloy material having a composition represented by the following formula: 0.01% by weight, and the remainder being Cu containing inevitable impurities:
(7) The method for producing an electrode material according to (6) above, wherein the extrusion is performed by changing the extrusion direction to the side with an inner angle of less than 180 ° C. to give a shear deformation.
(8) The method for producing an electrode material according to (6) or (7) above, wherein extrusion is performed at an extrusion ratio of 4 or more.

  According to the electrode material of the present invention and the method for producing the same, mechanical properties, heat resistance, high-temperature yield stress, and electrode material can be obtained by finely precipitating fine particles having an average crystal grain size of 50 nm or less in a fine crystal structure. Improves continuous spotting (electrode life) and promotes precipitation by promoting the precipitation of fine precipitates, suppresses alloying with the material to be welded as the electrode material, and improves the number of welding spots (welding resistance) An electrode material that can be provided can be provided. Furthermore, an electrode material having the excellent characteristics can be easily produced.

As a specific method for obtaining the electrode material of the present invention, an alloy material having a specific composition is formed at a recrystallization temperature or lower by an extrusion method and a side extrusion method (ECAE method: equal-channel angular extrusion). Is preferably used.
First, the extrusion method will be described.
Concrete for crystallizing alloy material crystal grains (specifically, non-equal axis grains with an aspect ratio of 1.5 or more) and substructure of the substructure to precipitate fine particles As an appropriate means, an extrusion method comprising direct extrusion or indirect extrusion performed at a temperature of 300 to 600 ° C. and an extrusion ratio of 4 or more is effective. In the extrusion method, the cross-sectional area of the alloy material is greatly changed, and according to the change of the cross-sectional area, it is possible to give shear deformation and plastic deformation (strain) to the alloy material by appropriately setting the conditions. . Thereby, precipitation of fine particles having a minor axis length of fibrous crystal grains of 10 μm or less, an average subcrystal grain size of the substructure of 3 μm or less, and an average crystal grain diameter of 50 nm or less can be promoted at a high temperature. High yield stress, heat resistance, and high conductivity can be imparted to the material.

  The extrusion molding apparatus used for the extrusion method in the present invention will be described based on the direct extrusion molding apparatus shown in FIG. 1. The supply section 1 communicating in the longitudinal direction is provided on one end side of the supply section 1 and the supply section 1. The die 3 formed with an opening having a cross-sectional shape of the extrusion molding material M to be molded and the other end side of the supply unit 1 and a dummy block on one side sliding in the supply unit 1 toward the die 3 4 and a stem 5 with 4.

Although not shown, the extrusion molding apparatus is provided with heating / cooling means, temperature detection means, temperature control means, and the like for controlling the temperature in the container 2.
The extrusion molding is formed on the die 3 by arranging the extrusion material S in the supply unit 1, sliding the stem 5 on the other end side toward the die 3, and pressing the extrusion material S toward the die 3. An extrusion molding material M having a cross-sectional shape matching the opening is prepared. In this case, by reducing the cross-sectional area of the extruded material S with the die 3, the material is distorted, and the extruded material has a crystallized fiber shape and a sub-crystal grain of the substructure is refined and further refined. Precipitation of particles is promoted by strain induction, and excellent mechanical properties can be improved.

  By applying this method to the alloy material, the minor axis length of the fibrous crystal grains is set to 10 μm or less and the average subcrystal grain size of the substructure is set to 3 μm or less in a very simple process. The particle size is reduced to 50 nm or less, and the high-temperature yield stress, heat resistance, toughness, and conductivity can be greatly improved. The process also has an effect on the fracture and homogenization of cast structure, macro of alloy components, micro segregation.

  In the present invention, it is important that extrusion by the above extrusion method is performed at a temperature of 300 to 600 ° C. and an extrusion ratio of 4 or more. The reason is that, when the temperature is less than 300 ° C., the mechanical strength is improved, but the precipitation cannot be sufficiently promoted to prevent the precipitation of fine precipitates, and the conductivity cannot be improved. If the temperature exceeds ℃, the crystal grains become fibrous, the substructure grains cannot be refined, the precipitated particles cannot be refined, and the mechanical strength cannot be improved. This is because re-dissolution occurs and the conductivity cannot be improved. Furthermore, when the extrusion ratio is less than 4, the alloy material crystal grains are made fibrous, the substructure grains of the substructure are not refined, and the precipitation of the fine particles is not sufficiently promoted, and the mechanical strength and conductivity are improved. This is because it cannot be expected.

  Furthermore, in the present invention, it is preferable to perform a heat treatment (hereinafter, also referred to as a preheat treatment) within a temperature range of 350 to 700 ° C. in advance in performing the extrusion method. By applying this pre-heat treatment, fine precipitates are dispersed, contributing to pinning such as dislocations introduced in the extrusion process, and making the crystal grains fibrillated and sub-crystal grains in the substructure can be made finer. . When the temperature is less than 350 ° C., precipitation does not occur, and when the temperature exceeds 700 ° C., the crystal grain size and precipitates are too coarse, and even if the above extrusion method is applied, suitable fibrous crystal grains It becomes impossible to control the minor axis length and the subcrystal grain size of the substructure or the size of the precipitate. About the prior heat processing time, the said effect can be anticipated if it is at least 30 minutes or more. In addition, although there is no restriction | limiting in particular about an upper limit, when it considers economical efficiency etc., it is desirable that it is less than 100 hours.

  In the present invention, it is preferable to perform a heat treatment (hereinafter also referred to as a post-heat treatment) within a temperature range of 350 to 700 ° C. after performing the above extrusion method. Since it can be uniformly and finely deposited and dispersed, the electrical conductivity can be improved as an electrode material. When the temperature is lower than 350 ° C., the amount of the precipitate deposited is insufficient, and the conductivity is not improved. On the other hand, when the temperature exceeds 700 ° C., the precipitated dispersed particles are re-dissolved and the conductivity tends to decrease. About the heat processing time, the said effect can be anticipated if it is at least 10 minutes or more. In addition, although there is no restriction | limiting in particular about an upper limit, when it considers economical efficiency etc., it is desirable that it is less than 50 hours.

  In the present invention, the combined use of the pre-heat treatment and the post-heat treatment controls the short axis length of the fibrous crystal grains, the average subcrystal grain size and the fine precipitates to an appropriate size, This is particularly preferable for uniformly dispersing fine precipitates and controlling the amount of precipitation.

Next, the side extrusion method (ECAE method) will be described.
The ECAE method changes the extrusion direction to the side of an inner angle of less than 180 ° (more preferably in the range of an inner angle of 60 to 120 °) in the middle without changing the cross-sectional area of the alloy material. It is possible to give plastic deformation (strain) corresponding to elongation of 220% or more, further 10,000% or more. Thereby, precipitation of fine particles having an equiaxed shape with an average crystal grain size of 3 μm or less and an average particle diameter of 50 nm or less can be promoted, and high strength and heat resistance can be imparted to the material.

  In the ECAE method of the present invention, as shown in FIG. 2, two extrusion containers having the same cross-sectional area on the inner surface, or the container 21 and the die 22 are joined at an appropriate angle (2φ) of less than 180 °, and one container is In this method, the alloy material S is inserted into the material 21 and extruded toward the next container 21 or die 22 by the ram 23 to apply a shear deformation in the lateral direction to the material. Preferably, this step is performed a plurality of times. By applying this method to the alloy material, the crystal grains can be refined to 3 μm or less by a very simple process and without reducing the cross-sectional area, and the toughness can be greatly improved (Japanese Patent Laid-Open No. 9-1990). No. 133244).

  The process also has an effect on fracture and homogenization of cast structure, macro of alloy components, micro segregation, and omits high temperature and long time homogenization heat treatment that is generally performed for alloy materials. It is also possible. Furthermore, even if the die 2 is accompanied by a reduction in the cross-sectional area, the effect does not change.

The amount of shear deformation applied to the alloy material by the ECAE method in the present invention varies depending on the bonding angle between the two containers or the container and the die. In general, the strain amount Δε _i per one extrusion due to such shear deformation is given by the following equation (1).

Δε _i = (2 / √3) · cotanφ (1)
ERR = (A ₀ / A) = exp (Δε _i ) (2)
EAR = {1- (1 / ERR)} × 100 (3)
EE = (ERR-1) × 100 (4)
(Where Δε _i is the strain amount, φ is 1/2 of the joining angle, ERR is the area ratio before and after processing, A ₀ is the cross-sectional area before processing, A is the cross-sectional area after processing, and EAR is the equivalent cross-section before and after processing) (Decrease rate, EE represents equivalent strain (synonymous with elongation).)

  In other words, when the inner angle of two containers or container-die joint is a right angle (90 °), the strain amount is 1.15 (equivalent elongation: 220%) by one side extrusion, and when 120 °, the strain amount is 120 °. Is given by 0.67 (equivalent elongation: 95%). By performing side extrusion at a right angle while maintaining the same cross-sectional area, it is possible to add a process corresponding to a rolling reduction (cross-sectional reduction rate) of 69% by rolling.

By repeating the above process, infinite strain can be accumulated in the material without changing the cross-sectional area of the material. The accumulated strain amount ε _t given to the material by the repetition is given by the following equation (5).
ε _t = Δε _i × N (5)
(However, ε _t represents the amount of accumulated strain, and N represents the number of extrusions.)

  The number of repetitions (N) is theoretically better as much as possible, but in reality, the effect is saturated in a certain number of times depending on the alloy. With a general wrought alloy material, a sufficient effect can be obtained with 4 repetitions (when the joining angle is a right angle, the cumulative strain amount is 4.6 and the equivalent elongation is 10,000%). Infinite strain can also be accumulated by rolling, but in that case, the cross-sectional area becomes infinitely small, which is in contrast to the side extrusion method.

  In the present invention, it is important that the ECAE method is performed at a temperature of 300 to 500 ° C. This temperature range is because when the temperature is less than 300 ° C., the mechanical strength is improved, but the precipitation cannot be sufficiently promoted to prevent the precipitation of fine precipitates, and the conductivity cannot be improved. When the temperature exceeds 500 ° C., the crystal grains cannot be refined, and the precipitated particles cannot be refined, the mechanical strength and the like cannot be improved, and re-dissolution of the precipitated dispersed particles occurs. This is because the conductivity cannot be improved.

  Further, when performing the ECAE method, it is preferable to perform a heat treatment (hereinafter also referred to as a preheat treatment) within a temperature range of 350 to 700 ° C. in advance. By performing this preliminary heat treatment, fine precipitates are dispersed, contributing to pinning such as dislocations introduced in the ECAE process, and crystal grains can be refined. When the temperature is less than 350 ° C., precipitation does not occur, and when the temperature exceeds 700 ° C., the crystal grain size and the precipitate are too coarse, and even if the ECAE method is applied, an appropriate crystal grain size or precipitate is obtained. It becomes impossible to control to the size of. About the prior heat processing time, the said effect can be anticipated if it is at least 30 minutes or more. In addition, although there is no restriction | limiting in particular about an upper limit, when it considers economical efficiency etc., it is desirable that it is less than 100 hours.

  In the present invention, after the ECAE method, it is preferable to perform a heat treatment (hereinafter also referred to as a post-heat treatment) within a temperature range of 350 to 700 ° C. Since it can be uniformly and finely deposited and dispersed, the electrical conductivity can be improved as an electrode material. When the temperature is lower than 350 ° C., the amount of the precipitate deposited is insufficient, and the conductivity is not improved. On the other hand, when the temperature exceeds 700 ° C., the precipitated dispersed particles are re-dissolved and the conductivity tends to decrease. About the heat processing time, the said effect can be anticipated if it is at least 10 minutes or more. In addition, although there is no restriction | limiting in particular about an upper limit, when it considers economical efficiency etc., it is desirable that it is less than 50 hours.

  In the present invention, the combined use of the pre-heat treatment and the post-heat treatment controls the average crystal grain size and fine precipitates to an appropriate size, and uniformly finely disperses the fine precipitates. It is particularly preferable for controlling the amount.

The Cu-based alloy material used for the electrode material of the present invention is preferably an alloy having a composition represented by the general formula: Cu _bal. Cr _a Zr _b X _c . Here, X is at least one element selected from Fe, P, Co, Si, and Mn, and a, b, and c are 0.4 wt% ≦ a ≦ 1.5 wt% and 0.02 wt%, respectively. ≦ b ≦ 0.1 wt%, 0 ≦ Fe + P + [Co × 0.75] + [Si × 0.6] + [Mn × 0.35] <0.015 wt%, the balance being Cu containing inevitable impurities It is.
The reason why the composition ratio of each component constituting the alloy is limited will be described below.

<Zr>
When Zr is less than 0.02 wt%, the deposited Cr particles are likely to be coarsened, so that the heat resistance is not sufficient. On the other hand, if it exceeds 0.1 wt%, it interacts with Cr and increases the solid solubility limit of Cr, so that the conductivity (IACS) is lowered and sufficient electrode characteristics cannot be obtained.

<Cr>
Cr can precipitate fine precipitates that contribute to the improvement of heat resistance and high-temperature yield stress. When Cr is less than 0.4 wt%, the amount of Cr deposited is reduced and the amount of Cr dispersed is reduced, so that the strength is not sufficient. On the other hand, if the content is 1.5 wt% or more, the amount of Cr deposited increases, so that IACS decreases and sufficient electrode characteristics cannot be obtained.

<Fe, P, Co, Si, Mn>
If these components are dissolved in a total amount of 0.015 wt% or more, IACS will be 90% or less. When the IACS is 90% or less, the sharpness is reduced, and as is clear from the implementation data, the average number of welding points becomes small (less than 500), and it is necessary to frequently stop the line. Becomes worse. On the other hand, it is industrially unfavorable because it takes a great deal of manufacturing cost to make it 0.001 wt% or less, and therefore it is preferably 0.001 wt% or more and 0.015 wt% or less.
In particular, the ratio of Fe, P, Co, Si, and Mn should be controlled, and all of them reduce IACS by dissolving in Cu. Fe and P have the most adverse effects, and then lead to a decrease in IACS in the order of Co, Si, and Mn.
The ratio of the degree of influence is Co: 0.75, Si: 0.6, Mn: 0.35 on the basis of Fe: 1, Fe + P + Co × 0.75 + Si × 0.6 + Mn × 0.35 <0. It was revealed that excellent electrode characteristics can be obtained by controlling within the range of 015.

  The product of the present invention preferably has a hardness of Hv90 or higher. When the Hv is less than 90, the material collapses due to the temperature rise and pressure applied at the electrode tip due to welding energization, and the current density decreases due to an increase in electrode tip diameter, resulting in poor welding.

  In addition, the structure of the electrode material effective for the present invention is that the minor axis length of the non-equiaxial fibrous crystal grains having an aspect ratio of 1.5 or more is 10 μm or less, and the average subcrystal grain size of the substructure is 3 μm or less. The size of fine precipitates (dispersed particle diameter) is 50 nm or less. By setting it as such a structure, the high temperature yield stress in 500 and 600 degreeC can be 200 Mpa or more, and electrical conductivity (IACS) can be 90% or more. Furthermore, by making the structure of the minor axis length of the fibrous crystal grains 10 μm or less, the average subcrystal grain size of the substructure 1 μm or less, and the size of fine precipitates (dispersion particle diameter) 25 nm or less. The high temperature yield stress at 500 and 600 ° C. can be 250 MPa or more, and the conductivity (IACS) can be 90% or more.

  Another structure of the electrode material effective for the present invention is that fine particles having an average particle diameter (dispersion particle diameter) of 50 nm or less are precipitated in a structure composed of equiaxed crystal grains having an average crystal grain size of 3 μm or less. This is an organizational structure. By adopting such a structure, the room temperature hardness (Hv) can be 100 or more, the conductivity (IACS) can be 90% or more, and the average crystal grain size is 1 μm or less, the size of fine precipitates. By adopting a structure having a (dispersed particle diameter) of 25 nm or less, the room temperature hardness (Hv) can be 120 or more and the conductivity (IACS) can be 90% or more.

Moreover, the dispersion state of fine precipitates that contribute to the improvement of heat resistance is 200 nm or less, preferably 100 nm or less, in terms of the average interparticle distance. Dispersion of particles having a diameter of 50 nm or less at the above intervals makes it possible to suppress a decrease in hardness after being held at 600 ° C. for several hours. In the present invention, specific examples of the fine precipitate to be precipitated include Cu—Zr series such as Cr, Cu ₃ Zr and Cu ₉ Zr ₂ , Fe, Cu ₃ P and the like.

  EXAMPLES Hereinafter, although this invention is demonstrated concretely based on an Example and a comparative example, it cannot be overemphasized that this invention is not limited to a following example.

[Example 1] Example of production by extrusion method (production of electrode material)
In a high frequency melting furnace, electrolytic copper and various gold were melted in an argon atmosphere and cast into a graphite mold to obtain an ingot having a diameter of 40 mm and a length of 300 mm. The composition of the obtained ingot was subjected to composition analysis by ICP emission analysis. This ingot was solution-treated at 1000 ° C. for 2 hours, and then age-hardened at 500 ° C. for 8 hours.
Each produced material was machined to a size of Φ40 × 70 mm. This standard round bar is heated to 500 ° C. in about 1 minute by a high-frequency heating device, immediately inserted into the extruder container shown in FIG. 1, and then warm extruded under conditions of an extrusion ratio of 5.5 and an extrusion speed of 1 mm / sec. To do. The extruded Φ18.5 round bar was heat-treated at 500 ° C. for 8 hours to obtain a final treated material.

(Alloy structure)
A structural photograph of the final treated material (sample No. 5) is shown in FIG. The structure of the extruded material is composed of fibrous crystal grains having a minor axis length of 10 μm or less composed of sub-crystal grains having an average particle diameter of 3 μm or less, and fine particles having an average particle diameter of 50 nm or less are included in the particle spacing of 200 nm or less. Are distributed. Moreover, Fe, P, Co, Mn, and Si were dissolved in the structure.

(Evaluation of room temperature hardness and conductivity)
Table 1 shows the measurement results of room temperature hardness (Hv) and electrical conductivity at room temperature (% IACS) of the final treatment material together with the alloy composition in the same manner as in Example 1. It can be seen that the samples (samples 3 to 7) of the present invention have increased conductivity (% IACS) to 90% or more.

(Evaluation of electrode life and welding resistance)
In order to evaluate the electrode performance, an electrode having a diameter of Φ16 mm (tip R8) −tip flat portion diameter of Φ6 mm was prepared, and a hot-dip galvanized steel sheet having a thickness of 0.7 mm as a welding base material (average plating adhesion amount: 45 g / m ²⁾ ) And a test was conducted using a single-phase AC stationary spot welder. The welding current was 11 kA, the energization time was 8 cycles, the applied pressure was 2.5 kN, and the continuous welding speed was 1 time / 1 s. The electrode life was evaluated based on the number of hits when the welded part was peeled off and the nugget diameter was less than 5 mm. The average number of welding points was the number of points at the time when the electrode material and the welded base material were stuck with a strength exceeding 10 kgf.
Further, the same criteria as those employed in Example 1 were adopted as the evaluation criteria for electrode life, welding resistance, and comprehensive evaluation.
The evaluation results are shown in Table 1. In the table, a double-frame cell indicates a numerical value outside the numerical range defined by the present invention.

No. in Table 1 In 1.2, the thermal stability was not sufficient, the hardness decreased remarkably with increasing temperature during use, and the number of continuous hits was less than 1000. No. Nos. 8 to 10 have a high solid solution amount of the additive element and a low conductivity (% IACS) (not shown in the table but the thermal conductivity is too low), so the Joule heat generation is very high and the heat removal rate Therefore, the crystal grains grew and the toughness was lowered, and it was easy to form an alloy with the welded material, and the average number of welding hit points was less than 500 times.
No. For the materials having a composition range of 11 to 14 in which the total composition amount of Fe, P, Co, Si, and Mn is greater than 0.015 wt%, the average number of welding points was less than 500 for the same reason.

Moreover, the sample was created with the following manufacturing methods as a comparison with this manufacturing method.
In a high frequency melting furnace, electrolytic copper and various gold were melted in an argon atmosphere and cast into a graphite mold to obtain an ingot having a diameter of 40 mm and a length of 300 mm. The ingot was extruded into a 25 mm square bar at a temperature of 900 ° C. After extrusion, solution treatment was performed at 1000 ° C. for 2 hours, and aging treatment was performed at 500 ° C. for 8 hours (see sample No. 1 in Table 2).

  Comparative Conventional Material No. 1 has a large amount of solid solution of Cr and the conductivity (% IACS) is too low (not shown in the table but the thermal conductivity is too low), so the Joule heat generation is very high and the cooling efficiency is poor. Furthermore, since the thermal stability was low, the hardness decreased remarkably with increasing electrode material temperature. As a result, the tip diameter of the electrode material is expanded with a small number of hit points, and the weld electrode density is lowered, so that the number of continuous hit points is low. As for the welding resistance, the electrical conductivity (% IACS) is too low (not shown in the table, but the thermal conductivity is too low), and the toughness is low due to the large crystal grain size of several tens of micrometers. Therefore, it is easy to alloy with the material to be welded, and the average number of welding points is small.

[Example 2] Production example by ECAE method (production of electrode material)
In a high frequency melting furnace, electrolytic copper and various gold were melted in an argon atmosphere and cast into a graphite mold to obtain an ingot having a diameter of 40 mm and a length of 300 mm. The composition of the obtained ingot was subjected to composition analysis by ICP emission analysis. The ingot was extruded into a 25 mm square bar at a temperature of 900 ° C. After extrusion, solution treatment was performed at 1000 ° C. for 2 hours, and pre-heat treatment was performed at 600 ° C. for 1 hour. After the pre-heat treatment, each material is inserted into one of two containers connected at right angles shown in FIG. 2, and side extrusion is repeated 4 times at a speed of 1 mm / second at 500 ° C. Obtained. After the side extrusion treatment, each material was heat-treated at 500 ° C. for 1 hour to obtain a final treated material.

(Alloy structure)
A structural photograph of the final treated material (sample No. 6) is shown in FIG. The crystal grain size before the side treatment was 50 to 100 μm, but the crystal grain size of the final treated material was equiaxed to 3 μm or less, and the size of fine precipitates was refined to 50 nm or less. The distance between the fine precipitates is also 200 nm or less, and the fine precipitates are uniformly dispersed in the structure. Moreover, Fe, P, Co, Mn, and Si were dissolved in the structure.

(Evaluation of room temperature hardness and conductivity)
Table 2 shows the measurement results of room temperature hardness (Hv) and electrical conductivity at room temperature (% IACS) of the final treated material together with the alloy composition. It can be seen that the room temperature hardness (Hv) is equal or slightly lower than that of the conventional material, but the conductivity (% IACS) of the material with the alloy composition adjusted is increased to 90% or more. The hardness measurement is the result of measuring the hardness with a micro Vickers hardness tester with a load of 50 gf. In addition, the conductivity measurement is a result of mirror polishing the surface of the final treatment material, and contacting the measurement probe of a digital conductivity meter (Auto Sigma 300) with the sample surface to measure the numerical value.

(Evaluation of electrode life and welding resistance)
In order to evaluate the life of the electrode, it was formed into an electrode having a tip diameter of 6 mm (40R), and a shot dull finish material of an Al-Mg alloy plate having a plate thickness of 1.6 mm was pickled as a welding base material. What applied viscosity mineral oil was used, and the spot welding test was done using the single phase alternating current stationary spot welding machine, water-cooling an electrode. The welding current was 31 kA, the energization time was 10 cycles, and the applied pressure was 500 kgf. Welding conditions were in accordance with WES7302, and a condition that a nugget with a diameter of 5 mm was obtained, and the continuous welding speed was 1 time / 2 seconds. The electrode life was evaluated by the number of hits at which the welded part was peeled off and the nugget diameter (the value obtained by adding the major axis and the minor axis and divided by 2) was less than 5 mm.
In the above electrode life evaluation test, when the electrode material and the material to be welded stick, the load when the electrode material is pulled and separated by a tensile tester is measured, and when the load exceeds 10 kgf, it is referred to as “welding” The number of hitting points until welding was taken as the number of welding hits, and the average value was taken as the average number of welding hits.

The standards for electrode life, welding resistance and comprehensive evaluation were as follows.
[Electrode life evaluation criteria]
○: More than 1000 consecutive hit points ×: Less than 1000 consecutive hit points
[Evaluation criteria for welding resistance]
○: Average number of welding points 500 times or more ×: Average number of welding points 500 or less [Comprehensive evaluation]
○: Both continuous dot resistance and welding resistance are evaluated ○
Δ: Evaluation of continuous spotting and welding resistance includes x. ×: Both evaluation of continuous spotting and welding resistance are x.
The evaluation results of each sample are shown in Table 2. In the table, a double-frame cell indicates a numerical value outside the numerical range defined by the present invention.

  No. 2.3.4 in Table 2 had insufficient thermal stability, the hardness decreased remarkably as the temperature increased during use, and the number of continuous hits was less than 1000. In Nos. 24-33, the additive element has a large solid solution amount and a low conductivity (% IACS) (not shown in the table, but the thermal conductivity is too low), so the Joule heat generation is very high, and the heat removal. Since the speed was low, the crystal grains grew and the toughness was lowered, and it was easy to alloy with the material to be welded, and the average number of deposition hit points was less than 500 times.

  Comparative conventional material No. 1 has a large amount of solid solution of Cr and the conductivity (% IACS) is too low (not shown in the table but the thermal conductivity is too low), so the Joule heat generation is very high and the cooling efficiency is poor. Furthermore, since the thermal stability was low, the hardness decreased remarkably with increasing electrode material temperature. As a result, the tip diameter of the electrode material is expanded with a small number of hit points, and the weld electrode density is lowered, so that the number of continuous hit points is low. As for the welding resistance, the electrical conductivity (% IACS) is too low (not shown in the table, but the thermal conductivity is too low), and the toughness is low due to the large crystal grain size of several tens of micrometers. Therefore, it is easy to alloy with the material to be welded, and the average number of welding points is small.

From the above, it has been clarified that a material with fine grains having high hardness, high conductivity (% IACS) and high thermal stability is excellent in welding characteristics.
Further, a material having a total composition amount of Fe, P, Co, Si, and Mn of less than 0.001 wt% was very difficult to manufacture, and thus could not be manufactured.

  The electrode material of the present invention has high toughness and electrical conductivity, and is excellent in continuous spotting performance (electrode life) and number of welding spots (welding resistance), so aluminum, magnesium, iron and alloys thereof, and metal plating materials thereof, etc. It is highly usable as an electrode material used when welding a material to be welded.

It is a figure which shows an example of the extrusion molding apparatus used in this invention. It is a figure which shows an example of the side extrusion molding apparatus used in this invention. It is a figure which shows the metal structure of the final processing material obtained in Example 1 (by EBSP and TEM). It is a figure which shows the metal structure of the final processing material obtained in Example 2 (by EBSP and TEM).

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Supply part 2 Container 3 Die 4 Dummy block 5 Stem 21 Container 22 Die 23 Ram S Alloy material M Extrusion material

Claims (8)

General formula: Cu _bal. Cr _a Zr _b X _c (where X is at least one element selected from Fe, P, Co, Si, and Mn, and a, b, and c are each 0.4 wt%. ≦ a ≦ 1.5 wt%, 0.02 wt% ≦ b ≦ 0.1 wt%, 0 ≦ Fe + P + [Co × 0.75] + [Si × 0.6] + [Mn × 0.35] <0.015 wt %, And the balance is Cu containing inevitable impurities), and the structure of the composition has a minor axis length of 10 μm or less composed of sub-crystal grains having an average grain size of 3 μm or less 2. The electrode material according to claim 1, wherein the electrode material has a structure in which fine particles having an average crystal particle diameter of 50 nm or less are deposited in a structure composed of fibrous crystal grains. General formula: Cu _bal. Cr _a Zr _b X _c (where X is at least one element selected from Fe, P, Co, Si, and Mn, and a, b, and c are each 0.4 wt%. ≦ a ≦ 1.5 wt%, 0.02 wt% ≦ b ≦ 0.1 wt%, 0 ≦ Fe + P + [Co × 0.75] + [Si × 0.6] + [Mn × 0.35] <0.015 wt %, And the balance is Cu containing inevitable impurities), and the structure of the composition is an average crystal grain in a structure composed of equiaxed crystal grains having an average crystal grain size of 3 μm or less. An electrode material having a structure in which fine particles having a diameter of 50 nm or less are precipitated. General formula: Cu _bal. Cr _a Zr _b X _c (where X is at least one element selected from Fe, P, Co, Si, and Mn, and a, b, and c are each 0.4 wt%. ≦ a ≦ 1.5 wt%, 0.02 wt% ≦ b ≦ 0.1 wt%, 0.001 ≦ Fe + P + [Co × 0.75] + [Si × 0.6] + [Mn × 0.35] <0 3. The electrode material according to claim 1, wherein the electrode material has a composition represented by the following formula: 0.15 wt% and the balance being Cu containing inevitable impurities.   The electrode material according to any one of claims 1 to 3, wherein the fine particles are dispersed and dispersed in an average interparticle distance of 200 nm or less. The electrode material according to claim 1, wherein the fine particles are at least one selected from Cr, Cu ₃ Zr, and Cu ₉ Zr ₂ . General formula: Cu _bal. Cr _a Zr _b X _c (where X is at least one element selected from Fe, P, Co, Si, and Mn, and a, b, and c are each 0.4 wt%. ≦ a ≦ 1.5 wt%, 0.02 wt% ≦ b ≦ 0.1 wt%, 0 ≦ Fe + P + [Co × 0.75] + [Si × 0.6] + [Mn × 0.35] <0.015 wt %, And the balance is Cu containing inevitable impurities), and a Cu-based alloy material having a composition represented by the following formula is extruded at a temperature of 300 to 600 ° C.   7. The method for producing an electrode material according to claim 6, wherein the extrusion is performed by changing the extrusion direction to the side with an inner angle of less than 180 [deg.] C. to give a shear deformation.   8. The method for producing an electrode material according to claim 6, wherein the extrusion is performed at an extrusion ratio of 4 or more.

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