JP5690169B2 - Copper alloy - Google Patents

Description

  The present invention relates to a copper alloy having not only good conductivity but also high strength, excellent bending workability, and excellent stress relaxation resistance, in particular, a connector constituting an electric / electronic component, The present invention relates to a copper alloy for electrical and electronic parts that can be suitably used for energized parts such as lead frames, relays, and switches.

  Copper alloy materials used for current-carrying parts such as connectors, lead frames, relays, and switches that make up electrical and electronic parts are required to have good conductivity in order to suppress the generation of Joule heat due to current flow. High strength is required to withstand the stress applied during assembly and operation of electrical / electronic components. Further, electric / electronic parts are generally formed by bending, and excellent bending workability is required for the material for electric / electronic parts to be bent. Furthermore, in order to ensure the contact reliability of electric / electronic parts, it is also required that the contact pressure is reduced with time, that is, it is excellent in stress relaxation resistance which is durability against stress relaxation.

  Methods for increasing the strength of materials used in these current-carrying parts include adding a large amount of solute elements such as Ni and Si, repeating annealing and rolling during manufacturing, and finishing rolling after aging treatment (tempering) A method for increasing the processing rate is generally known. However, the addition of a large amount of solute elements such as Ni and Si causes an increase in the amount of Ni-Si inclusions, resulting in a problem that bending workability is lowered. Further, in the method of increasing the finish rolling (tempering treatment) rate, the Cube azimuth area rate is lowered, and the problem that the bending workability is similarly lowered occurs.

  Moreover, as a method of improving the bending workability of the material used for the current-carrying parts, a method of decreasing the finish rolling (tempering treatment) rate, a method of refining the crystal grain size, or increasing the Cube orientation area ratio Methods are generally known. However, when the crystal grain size is made finer, the problem that the stress relaxation resistance is lowered occurs.

  Furthermore, as a method of improving the stress relaxation resistance of the material used for the current-carrying parts, a method of reducing the finish rolling (tempering treatment) rate and a method of increasing the crystal grain size are generally known. ing.

  Therefore, even with various conventional technologies, it is possible to simultaneously increase the strength of materials used for current-carrying parts that make up electrical and electronic parts, improve bending workability, and improve stress relaxation characteristics. It can be said that it is very difficult. Therefore, in the past, in view of the characteristics required for each current-carrying part to be manufactured, it has been necessary to take a method of responding by appropriately balancing these characteristics. In particular, among the copper alloys, the Corson alloy (Cu—Ni—Si based copper alloy) is excellent in various characteristics and is inexpensive, and therefore is a copper alloy material suitable for energizing parts constituting electric / electronic parts. In recent years, it has been widely adopted.

  In recent years, electronic devices have been reduced in size and weight, and there is a tendency for copper alloy materials used for terminals and connectors to have a particularly high demand for high strength and thinness. Accordingly, among the strengths, a high 0.2% proof stress (YP) in the direction perpendicular to the rolling direction (TD direction) tends to be particularly required from the viewpoint of contact pressure strength.

  However, in particular, the Corson alloy has a feature that the difference in strength between the rolling parallel direction (LD direction) and the rolling perpendicular direction (TD direction) is large, that is, the strength in the direction perpendicular to the rolling is higher than the strength in the rolling parallel direction. The characteristic is that it is relatively low. Moreover, there is also a feature that the difference between the tensile strength (TS) and the 0.2% proof stress (YP) is large. For this reason, when this Corson alloy is used for a terminal / connector, the proof stress in the direction perpendicular to the rolling becomes low and the contact pressure strength is insufficient.

  In recent years, various methods for improving the bending workability of this Corson alloy have been proposed. For example, Patent Document 1 proposes a technique for controlling the texture of crystal grains as an effective method for improving the bending workability of a Corson alloy. In Patent Document 1, an average crystal grain size of a Corson alloy containing Ni in a range of 2.0 to 6.0% by mass and Si in a range of 4 to 5 by mass ratio of Ni / Si is set to 10 μm or less. The measurement result by the SEM-EBSP method has a texture where the ratio of the Cube orientation {001} <100> is 50% or more, and has a layered boundary that can be observed by a structure observation with a 300 times optical microscope. A copper alloy plate is disclosed.

  Further, according to Patent Document 2, the material surface of a copper alloy containing 0.5 to 4.0% by mass of Ni, 0.5 to 2.0% by mass of Co, and 0.3 to 1.5% by mass of Si. The diffraction intensity from the {111} plane is I {111}, the diffraction intensity from the {200} plane is I {200}, and the diffraction intensity from the {220} plane is I {220}, {311} plane Is the diffraction intensity from {200} plane, and the ratio of the diffraction intensity from {200} plane in these diffraction intensities is R {200} = I {200} / (I {111} + I {200} + I {311}), a proposal has been made regarding a copper alloy for electrical and electronic equipment in which R {200} is 0.3 or more.

Furthermore, according to Patent Document 3, in a copper alloy sheet containing Ni: 0.7 to 2.5% and Si: 0.2 to 0.7% by mass%, 3.0 ≦ I {220} / By satisfying I ₀ {220} ≦ 6.0, 1.5 ≦ I {200} / I ₀ {200} ≦ 2.5, while maintaining the high strength and excellent bending workability of the Corson alloy, Proposals have been made on copper alloy sheet materials with improved anisotropy regarding their properties.

Further, according to Patent Document 4, in a copper alloy sheet material containing Ni: 0.7 to 4.2% and Si: 0.2 to 1.0% by mass%, I {420} / I ₀ {420} By satisfying> 1.0, a proposal has been made regarding a copper alloy sheet that exhibits excellent bending workability and stress relaxation resistance while maintaining high strength and high conductivity.

JP 2006-152392 A JP 2009-7666 A JP 2008-13836 A JP 2008-223136 A

  The present invention has been made in view of the above-described conventional situation, and it is a copper alloy having not only good conductivity but also high strength, excellent bending workability, and excellent stress relaxation resistance. The issue is to provide.

The invention according to claim 1 is a copper alloy containing Ni: 1.5 to 3.6% and Si: 0.3 to 1.0% by mass, with the balance being made of copper and inevitable impurities. In addition, the average crystal grain size of the crystal grains of this copper alloy is 5 μm to 30 μm, and the area ratio occupied by crystal grains having a crystal grain size more than twice the average crystal grain size is 3% to 20% . In addition, among the areas occupied by crystal grains having a crystal grain size twice or more of the average crystal grain size, the area ratio occupied by Cube orientation grains is 50% or more.

  Invention of Claim 2 is a copper alloy of Claim 1 which contains Sn: 0.05-3.0% and / or Zn: 0.05-3.0% by the mass% further.

  The invention according to claim 3 further comprises 0.01 to 3.0% in total of one or more of Fe, Mn, Mg, Co, Ti, Cr and Zr in mass%. The copper alloy according to 1 or 2.

  According to the present invention, the copper alloy has not only good conductivity, but also high strength, excellent bending workability, and excellent stress relaxation resistance, that is, bending workability and resistance. A high-strength copper alloy having excellent stress relaxation characteristics can be obtained.

It is a front view which shows the test method which calculates | requires the stress relaxation characteristic of copper alloy in an Example, and shows the state which gave the deflection amount to the strip-shaped test piece. It is a front view which shows the test method which calculates | requires the stress relaxation resistance characteristic of a copper alloy in an Example, and shows a permanent deflection when the deflection amount is removed.

  The most effective method for increasing the strength of a copper alloy is to increase the finish rolling (tempering treatment) rate. However, if the finish rolling (tempering treatment) rate is increased, the bending workability and stress relaxation resistance of the copper alloy will be reduced. Moreover, the most effective means for improving the stress relaxation resistance is to increase the crystal grain size of the copper alloy. However, when the crystal grain size is increased, the bending workability of the copper alloy is reduced. Therefore, when trying to obtain a copper alloy that combines strength, bending workability, and stress relaxation resistance with conventional techniques, the finish rolling (tempering treatment) rate and crystal grain size are controlled to achieve strength. , To obtain a copper alloy that has the contradictory properties of high strength, excellent bending workability, and excellent stress relaxation properties, by adopting a method that appropriately balances bending workability and stress relaxation resistance. Was impossible.

  In view of such conventional problems, the present inventors have intensively conducted experiments and research in order to obtain a copper alloy having high strength, excellent bending workability, and excellent stress relaxation resistance.

  The present inventors considered that the crystal grain size of the copper alloy is a critical factor for obtaining a copper alloy having high strength, excellent bending workability, and excellent stress relaxation properties, and started investigation. As a result, it is possible to suppress intergranular cracking during bending when only coarse grains exist by mixing fine grains and coarse grains to some extent in the crystal grain structure of the copper alloy. I found out. It was also found that excellent stress relaxation characteristics can be obtained by enlarging some of the crystal grains of the copper alloy.

  Furthermore, as a result of conducting a detailed investigation on the crystal grain size and crystal orientation using the SEM-EBSP, the present inventors disperse an appropriate amount of relatively coarse Cube orientation grains in the crystal grain structure of the copper alloy. As a result, it has been found that bending workability is particularly good. In addition, this Cube orientation grain is an orientation grain with many slip systems compared with other orientation grains. Therefore, even if a relatively coarse Cube orientation grain exists to some extent, bending workability is not deteriorated. Guessed.

  As a result of the above experiments and research, the present inventors determined that the average crystal grain size of the crystal grains in the copper alloy is 5 μm to 30 μm, and that the crystal grain size is twice or more the average crystal grain size. By making the area ratio of the crystal grains possessed in the crystal grain structure 3% or more, and further making 50% or more of the crystal grains having a crystal grain size more than twice the average crystal grain size as Cube orientation grains The present inventors have found that it is possible to obtain a copper alloy having high strength, excellent bending workability, and excellent stress relaxation resistance, which are the problems of the present invention.

  Hereinafter, embodiments of the present invention will be specifically described for each requirement. First, requirements regarding the crystal grain structure of the copper alloy of the present invention will be described in order.

(Average crystal grain size)
The average crystal grain size of the copper alloy is 5 μm to 30 μm. When the average crystal grain size is less than 5 μm, the stress relaxation resistance is deteriorated. On the other hand, when the average crystal grain size exceeds 30 μm, the bending workability of the copper alloy is deteriorated. For example, the evaluation standard described in the Japan Copper and Brass Association Technical Standard JBMA-T307 is worse than D or less. Therefore, the lower limit of the average crystal grain size of the copper alloy is 5 μm, and the upper limit is 30 μm. A more preferable lower limit of the average crystal grain size is 8 μm and an upper limit is 25 μm.

(Area ratio occupied by crystal grains having a crystal grain size more than twice the average crystal grain size)
The area ratio occupied by crystal grains having a crystal grain size more than twice the average crystal grain size (area of all crystal grains having a crystal grain size more than twice the average crystal grain size / area of all crystal grains) is 3%. When the ratio is less than 1, it is impossible to simultaneously realize excellent stress relaxation characteristics and excellent bending workability. Therefore, the lower limit of the area ratio occupied by crystal grains having a crystal grain size twice or more the average crystal grain size is set to 3%. A more preferred lower limit is 5%. On the other hand, it can be inferred that the larger the area ratio occupied by crystal grains having a crystal grain size more than twice the average crystal grain size, the more effective it is to simultaneously improve the stress relaxation resistance and bending workability. Actually, it is difficult with the current technology to make the area ratio occupied by crystal grains having a crystal grain size more than twice the average crystal grain size more than 20%.

(Area ratio occupied by Cube orientation grains)
The Cube orientation {001} <100> is an orientation in which more slip systems can be active. Of the area occupied by crystal grains having a crystal grain size twice or more of the average crystal grain size, the area ratio occupied by Cube orientation grains (area of the Cube orientation grains having a crystal grain size more than twice the average crystal grain size / It is possible to improve the bending workability of the copper alloy by setting the area of all crystal grains having a crystal grain size twice or more the average crystal grain size to 50% or more. When the area ratio is less than 50%, the bending workability of the copper alloy is lowered. For example, the evaluation standard described in the Japan Copper and Brass Association Technical Standard JBMA-T307 is worse than D or less. The area ratio occupied by more preferable Cube-oriented grains is 70% or more.

(Measuring method of average grain size and texture)
The present invention uses a crystal orientation analysis method in which a field emission scanning electron microscope (FESEM) is mounted on a field emission scanning electron microscope (FESEM). The texture of the surface portion of the alloy in the plate thickness direction is measured, and the crystal grain size is measured.

  In the EBSP method, an EBSP is projected onto a screen by irradiating an electron beam onto a sample set in a FESEM column. This is taken with a high-sensitivity camera and captured as an image on a computer. In the computer, the orientation of the crystal is determined by analyzing this image and comparing it with a pattern obtained by simulation using a known crystal system. The calculated crystal orientation is recorded as a three-dimensional Euler angle together with position coordinates (x, y) and the like. Since this process is automatically performed for all measurement points, tens of thousands to hundreds of thousands of crystal orientation data can be obtained at the end of measurement.

  Here, in the case of a normal copper alloy sheet, mainly formed a texture composed of many orientation factors called Cube orientation, Goss orientation, Brass orientation, Copper orientation, S orientation, etc. as shown below. There is a corresponding crystal plane. These facts are described in, for example, “Cross Texture” (published by Maruzen Co., Ltd.) edited by Shinichi Nagashima and “Light Metal” commentary Vol. 43, 1993, P285-293, and the like. The formation of these textures differs depending on the processing and heat treatment methods even in the case of the same crystal system. In the case of a texture of a plate material by rolling, it is expressed by a rolling surface and a rolling direction, the rolling surface is expressed by {ABC}, and the rolling direction is expressed by <DEF> (ABCDEF indicates an integer). Based on the expression, each direction is expressed as follows.

Cube orientation {001} <100>
Goss orientation {011} <100>
Rotated-Goss orientation {011} <011>
Brass orientation {011} <211>
Copper orientation {112} <111>
(Or D direction {4411} <11118>)
S orientation {123} <634>
B / G direction {011} <511>
B / S orientation {168} <211>
P direction {011} <111>

  In the present invention, basically, those whose orientations deviate within ± 15 ° from these crystal planes belong to the same crystal plane (orientation factor). Further, a boundary between crystal grains in which the orientation difference between adjacent crystal grains is 5 ° or more is defined as a crystal grain boundary.

  In addition, in the present invention, the measurement area 300 × 300 μm is irradiated with an electron beam at a pitch of 0.5 μm, the number of crystal grains measured by the crystal orientation analysis method is n, and each measured crystal grain size is x The average grain size is calculated as (Σx) / n.

  Further, the area ratio occupied by crystal grains having a crystal grain size more than twice the average crystal grain size is the total area of the corresponding crystal grains by irradiating the measurement area 300 × 300 μm with an electron beam at a pitch of 0.5 μm. Is obtained by a calculation of (area of all crystal grains having a crystal grain size more than twice the average crystal grain size / area of all crystal grains).

  The area ratio occupied by Cube orientation grains out of the area occupied by crystal grains having a crystal grain size more than twice the average crystal grain size is irradiated with electron beams at a pitch of 0.5 μm with respect to a measurement area of 300 × 300 μm. Then, the area of the corresponding Cube-oriented grains measured by the above-mentioned crystal orientation analysis method is measured, and (the area of Cube-oriented grains having a crystal grain size twice or more of the average crystal grain size / twice or more of the average crystal grain size) The area of all crystal grains having a crystal grain size of

  The crystal orientation distribution may be distributed in the thickness direction. Therefore, it is preferable to obtain some points arbitrarily in the thickness direction by obtaining an average.

(Chemical composition of copper alloy)
Next, the reasons for limiting the components of the copper alloy of the present invention will be described. Hereinafter, the content (ratio) of each element is simply described as%, but all indicate mass%.

Ni: 1.5% to 3.6%
Ni has the effect of securing the strength and conductivity of the copper alloy by crystallizing or precipitating a compound with Si. If the Ni content is less than 1.5%, the amount of precipitates generated becomes insufficient, the desired strength cannot be obtained, and the crystal grains of the copper alloy structure become coarse. On the other hand, if the Ni content exceeds 3.6%, the electrical conductivity is lowered, and the number of coarse precipitates is excessively increased, so that the bending workability is lowered. Therefore, the Ni content is in the range of 1.5% to 3.6%.

  The achievable strength level varies depending on the Ni content. When the Ni content is 1.5% to less than 2.0%, the 0.2% proof stress (YP) in the direction perpendicular to the rolling direction (TD direction) is 650 MPa or more, and the bending workability is the Japan Copper and Brass Association. It becomes possible to achieve each of the evaluation standards B and above described in the technical standard JBMA-T307. On the other hand, when the Ni content is 2.0% to 3.6%, the 0.2% proof stress (YP) in the direction perpendicular to the rolling direction (TD direction) is 700 MPa or more, and the bending workability is Nippon Shindoh. It becomes possible to achieve each of the evaluation criteria C and above described in the association technical standard JBMA-T307.

Si: 0.3% to 1.0%
Si improves the strength and electrical conductivity of the copper alloy by crystallizing or precipitating a compound with Ni. If the Si content is less than 0.3%, the formation of precipitates becomes insufficient, the desired strength cannot be obtained, and the crystal grains of the copper alloy structure become coarse. On the other hand, when the content of Si exceeds 1.0%, the number of coarse precipitates is excessively increased and bending workability is deteriorated. Therefore, the Si content is in the range of 0.3% to 1.0%.

  The achievable strength level varies depending on the Si content. When the Si content is less than 0.3% to less than 0.5%, the 0.2% yield strength (YP) in the direction perpendicular to the rolling direction (TD direction) is 650 MPa or more, and the bending workability is Japan Copper and Brass Association. It becomes possible to achieve each of the evaluation standards B and above described in the technical standard JBMA-T307. On the other hand, when the Si content is 0.5% to 1.0%, the 0.2% proof stress (YP) in the direction perpendicular to the rolling direction (TD direction) is 700 MPa or more, and the bending workability is Nippon Shindoh. It becomes possible to achieve each of the evaluation criteria C and above described in the association technical standard JBMA-T307.

  The copper alloy of the present invention is composed of copper and unavoidable impurities in addition to the above elements, but may contain the following elements alone or in combination.

Zn: 0.05% to 3.0%
Zn is an element effective for improving the heat-resistant peelability of Sn plating and solder used for joining electronic components and suppressing thermal peeling. In order to exhibit such an effect effectively, it is necessary to contain 0.05% or more. However, if the Zn content exceeds 3.0%, the wet-spreading property of molten Sn and solder is deteriorated, and the electrical conductivity is greatly reduced. Therefore, when Zn is contained, the range of 0.05% to 3.0% is taken into consideration in consideration of the effect of improving the heat-resistant peelability and the effect of decreasing the electrical conductivity.

Sn: 0.05% to 3.0%
Sn dissolves in the copper alloy and contributes to strength improvement. In order to exhibit this effect effectively, it is necessary to contain 0.05% or more. However, if the Sn content exceeds 3.0%, the effect is saturated and the conductivity is greatly reduced. Therefore, when Sn is contained, the range of 0.05% to 3.0% is set in consideration of the strength improvement effect and the conductivity lowering effect.

Totally 0.01% to 3.0% of one or more of Fe, Mn, Mg, Co, Ti, Cr and Zr
These elements are effective in reducing the crystal grains. Further, by forming a compound with Si, the strength and conductivity are improved. In order to effectively exhibit these effects, it is necessary to selectively contain one or more of Fe, Mn, Mg, Co, Ti, Cr, and Zr in a total of 0.01% or more. . However, if the total content of these elements exceeds 3.0%, the compound becomes coarse and the bending workability is impaired. Therefore, the content of these elements when selectively contained is in the range of 0.01% to 3.0% in total.

(Production conditions)
The copper alloy (copper alloy plate) of the present invention can be produced through hot rolling, cold rolling, solution treatment, aging treatment, and cold rolling, as in the case of producing a general copper alloy. However, when the present inventors diligently examined the production conditions for producing the copper alloy of the present invention, particularly by devising the hot rolling process, the high strength intended by the present invention, excellent bending workability It was also confirmed that a copper alloy having excellent stress relaxation characteristics can be produced. The manufacturing conditions will be described in detail below.

  Incidentally, the copper alloy of the present invention is basically a rolled copper alloy plate, and the strip formed by slitting the strip in the width direction, and those obtained by coiling these plates and strips are also included in the copper alloy of the present invention. It is.

  It is desirable that the hot rolling step be performed under the condition of holding for 10 minutes or more in a temperature range of 400 to 600 ° C. during cooling after the hot rolling is completed, and then rapidly cooling. When the holding temperature is less than 400 ° C. or more than 600 ° C., or the holding time is less than 10 minutes, the area ratio occupied by crystal grains having a crystal grain size twice or more the average crystal grain size tends to be less than 3%. Or, the area ratio occupied by the Cube orientation grains tends to be less than 50% of the area occupied by the crystal grains having a crystal grain size twice or more of the average crystal grain size. In that case, it becomes impossible to improve bending workability and stress relaxation resistance simultaneously.

  The rate of temperature rise in the subsequent solution treatment is desirably 0.1 ° C./s or less, and the rate of temperature decrease is desirably 100 ° C./s or more. When the rate of temperature increase is greater than 0.1 ° C./s, the area ratio occupied by crystal grains having a crystal grain size more than twice the average crystal grain size may be less than 3%. Cannot improve the bending workability and the stress relaxation resistance at the same time. On the other hand, if the rate of temperature decrease is lower than 100 ° C./s, precipitation may occur during cooling, and in that case, sufficient precipitation cannot be obtained in the subsequent aging treatment, causing a decrease in strength. .

  The solution treatment temperature is desirably 750 to 900 ° C. When the solution treatment temperature is lower than 750 ° C., the average crystal grain size of the crystal grains tends to be smaller than 5 μm, and the stress relaxation resistance is likely to deteriorate. On the other hand, when the solution treatment temperature is higher than 900 ° C., the average crystal grain size of the crystal grains tends to be larger than 30 μm, and the bending workability tends to deteriorate.

  After the solution treatment, the copper alloy of the present invention is produced through a process of aging treatment-final cold rolling (-low temperature annealing), similarly to the ordinary copper alloy production process. The aging temperature in the aging treatment is desirably 400 to 550 ° C., as in the case of producing a normal copper alloy.

  Further, the rolling reduction of the final cold rolling is desirably 25 to 60%. If the rolling reduction is less than 25%, the 0.2% proof stress (YP) in the direction perpendicular to the rolling direction (TD direction) becomes small and the strength tends to decrease. On the other hand, if the rolling reduction exceeds 60%, sufficient bending workability may not be obtained.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited by the following examples, and the present invention is implemented with appropriate modifications within a range that can meet the gist of the present invention. These are all included in the technical scope of the present invention.

  Examples of the present invention will be described below. Copper alloy thin plates of Cu—Ni—Si—Zn—Sn based copper alloys having various chemical composition shown in Tables 1 and 2 were produced under various conditions shown in Tables 1 and 2, and the average crystal grain size and The plate properties such as the texture, the plate properties such as the strength, conductivity, bending workability and stress relaxation resistance were investigated and evaluated. The results are shown in Tables 3 to 6.

  A specific method for producing a copper alloy plate is a 50 mm thick casting having a chemical composition as shown in Tables 1 and 2 by melting in the kryptor furnace in the atmosphere under a charcoal coating and casting into a cast iron book mold. A lump was obtained. And after chamfering the surface of the ingot, it is hot-rolled at a temperature of 950 ° C. until the thickness becomes 30 to 6 mm, and is cooled to 600 to 300 ° C. by air cooling from a temperature of 750 ° C. or higher. After holding for 1 minute to 120 minutes using a batch annealing furnace heated to 600 to 300 ° C., it was rapidly cooled in water. Next, after removing the oxide scale, cold rolling was performed to obtain a plate having a thickness of 0.20 to 0.33 mm.

  Then, using a batch furnace with a temperature rising rate of 0.03 to 0.05 ° C., a salt bath furnace with a temperature rising rate of 10 to 50 ° C./s, or an electric heater, listed in Table 1 and Table 2. Solution treatment was performed under various conditions, followed by water cooling.

  About the sample after these solution treatment (annealing), it passed through the process of aging treatment-final cold rolling, or final cold rolling-aging treatment, and it was set as the cold rolled sheet with a thickness of 0.15 mm. The cold-rolled sheet was subjected to a low-temperature annealing treatment of 480 ° C. × 30 s in a salt bath furnace to obtain a final copper alloy sheet.

(Organization)
Average crystal grain size, each area ratio defined in the present invention:
Take a structure observation piece from each obtained copper alloy thin plate, and mount the backscattered electron diffraction image system on the field emission scanning electron microscope with the average crystal grain size and each area ratio specified in the present invention as described above. The crystal orientation analysis method was used. Specifically, the surface of the rolled surface of the copper alloy thin plate was mechanically polished, and further subjected to electrolytic polishing after buffing to prepare a sample whose surface was adjusted. Thereafter, crystal orientation measurement and crystal grain size measurement by EBSP were performed using FESEM (JEOL JSM 5410) manufactured by JEOL Ltd. The measurement area was an area of 300 μm × 300 μm, and the measurement step interval was 0.5 μm.

  The measurement area was an area of 300 μm × 300 μm, and the measurement step interval was 0.5 μm. The measurement surfaces were each 3 points of 1/4 t part and 1/2 t part of the plate thickness, and each area ratio defined by the present invention was calculated from the average of a total of 6 points.

Tensile test:
The tensile test was performed using a JIS No. 13 B test piece in which the longitudinal direction of the test piece was the rolling direction, at a room temperature, a test speed of 10.0 mm / min, and GL = 50 mm using a 5882 type Instron universal testing machine And 0.2% proof stress (MPa) was measured. In this tensile test, three test pieces under the same conditions were tested, and the average value thereof was adopted.

conductivity:
Conductivity is measured by measuring the electrical resistance with a double-bridge resistance measuring device by processing a strip-shaped test piece having a width of 10 mm and a length of 300 mm by milling with the longitudinal direction of the test piece as the rolling direction. Calculated by the method. In this measurement as well, three test pieces under the same conditions were measured and the average value thereof was adopted.

Bending workability:
The bending test of the copper alloy plate sample was performed by the following method. A plate material having a width of 10 mm and a length of 30 mm was cut out from the copper alloy plate sample, and a load of 1000 kgf (about 9800 N) was applied to bend 90 degrees to Good Way (the bending axis was perpendicular to the rolling direction) with a bending radius of 0.15 mm. . Thereafter, 180 ° contact bending was performed with a load of 1000 kgf (about 9800 N), and the presence or absence of cracks in the bent portion was visually observed with a 50 × optical microscope. In that case, the evaluation of the crack was evaluated by A to E described in the Japan Copper and Brass Association Technical Standard JBMA-T307.

Stress relaxation resistance:
The stress relaxation resistance (stress relaxation rate) was measured using a cantilever method shown in FIGS. 1 and 2 by collecting a test piece from a copper alloy plate sample. Specifically, first, a strip-shaped test piece 1 having a width of 10 mm was cut out from a copper alloy plate sample so that the length direction was a direction perpendicular to the rolling direction of the plate material. Subsequently, after fixing one end of the strip-shaped test piece 1 to the rigid body test stand 2, a size of d (= 10 mm) as shown in FIG. The amount of deflection was given. The span length L is determined such that a surface stress corresponding to 80% of the material yield strength is applied to the material. In this state, the strip-shaped test piece 1 was held in an oven at 180 ° C. for 24 hours and then taken out, and the permanent distortion δ (shown in FIG. 2) when the deflection amount d was removed was measured, and RS = (δ / d) The stress relaxation rate (RS:%) was determined from the formula of x100.

  As a result of the above tests, the 0.2% proof stress (YP) in the direction perpendicular to the rolling (TD direction) in the tensile test is 650 MPa or more, the conductivity is 30% IACS or more, and the evaluation in the bending test is A to A. B, with a stress relaxation rate of 20% or less, or 0.2% yield strength (YP) in the direction perpendicular to the rolling (TD direction) in the tensile test is 700 MPa or more, conductivity is 30% IACS or more, bending When the evaluation in the test is A to C and the stress relaxation rate is 20% or less, the copper alloy having the high strength, high conductivity, excellent bending workability, and excellent stress relaxation resistance of the present invention. evaluate.

  As shown in Tables 1 and 2, Sample No. 1 to 18 are a chemical component composition, an average crystal grain size, an area ratio occupied by a crystal grain having a crystal grain size more than twice the average crystal grain size, and a crystal having a crystal grain size more than twice the average crystal grain size Of the area occupied by the grains, the area ratio occupied by the Cube-oriented grains is controlled within a specified range.

  As a result, sample no. 1-4, 6-18 have a 0.2% proof stress (YP) in the direction perpendicular to the rolling (TD direction) in the tensile test of 700 MPa or more, a conductivity of 30% IACS or more, and an evaluation in a bending test. It became the result of satisfying the requirements regarding the copper alloy of this invention that AC and stress relaxation rate were 20% or less.

  Sample No. 5: 0.2% proof stress (YP) in the direction perpendicular to the rolling (TD direction) in the tensile test is 650 MPa or more, conductivity is 30% IACS or more, evaluation in the bending test is A to B, stress relaxation The result was that the requirement for the copper alloy of the present invention was 20% or less.

  On the other hand, sample No. which is a comparative example. In 19 to 23, the content of any element does not satisfy the range defined in the present invention. Sample No. In 24-31, the average crystal grain size, the area ratio occupied by crystal grains having a crystal grain size twice or more than the average crystal grain size, the area occupied by crystal grains having a crystal grain size twice or more the average crystal grain size Of these, any one or more of the area ratios occupied by the Cube-oriented grains could not be controlled within the range defined by the present invention.

  As a result, in these comparative examples, as shown in Table 3, the 0.2% proof stress (YP) in the direction perpendicular to the rolling (TD direction) in the tensile test is 650 MPa or more, the conductivity is 30% IACS or more, The evaluation in the bending test is A to B, the stress relaxation rate is 20% or less, or the 0.2% proof stress (YP) in the direction perpendicular to the rolling (TD direction) in the tensile test is 700 MPa or more, and the conductivity is As a result, at least one item could not satisfy the requirements of 30% IACS or more, A to C in the bending test, and stress relaxation rate of 20% or less.

1 ... Strip-shaped specimen 2 ... Rigid body test stand

Claims (3)

It is a copper alloy containing Ni: 1.5-3.6%, Si: 0.3-1.0%, and the balance consisting of copper and inevitable impurities,
The average grain size of the crystal grains of this copper alloy is 5 μm to 30 μm,
The area ratio occupied by crystal grains having a crystal grain size more than twice the average crystal grain size is 3% to 20% ,
And the copper alloy characterized by the area ratio which a Cube azimuth grain occupies is 50% or more among the area which the crystal grain which has a crystal grain size 2 times or more of the average crystal grain size occupies.   Furthermore, the copper alloy of Claim 1 which contains Sn: 0.05-3.0% and / or Zn: 0.05-3.0% by the mass%. Furthermore, the copper alloy of Claim 1 or 2 which contains 0.01-3.0% in total of 1 type, or 2 or more types among Fe, Mn, Mg, Co, Ti, Cr, Zr by the mass%.