JP2012136726A - Cu-Ni-Si BASED COPPER ALLOY SHEET EXCELLENT IN FATIGUE RESISTANCE AND SPRING PROPERTY AFTER BENDING WORKING, AND METHOD OF MANUFACTURING THE SAME - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a Cu-Ni-Si based copper alloy sheet which has excellent fatigue resistance and a spring property even if used at high temperature and high oscillation environment for a long time after bending working of a prescribed shape as a raw material as a relay movable piece, a socket terminal or the like of various electric parts.SOLUTION: The Cu-Ni-Si based copper alloy sheet includes 1.0-3.0 mass% of Ni; 1/6-1/4 concentration of Si based on Ni, and a rest consisting of Cu and inevitable impurities, wherein orientations of all pixel in a measured area of a surface are measured at 0.5 μm of a step size by an EBSD method, an area ratio of a crystal grain in which an average orientation difference among the all pixel in the crystal grain is less than 4° when a border in which an orientation difference between abutting pixel is at least 5° is made a crystal grain boundary is 45-55% of a measured area, an area average GAM of a crystal grain existing in an area to be measured is 0.8-1.6°, a number of a Ni-Si precipitated object particle in which a particle diameter exceeds 100 nm is 0.2-0.7 piece/μm, and a concentration of Si solid solved in a crystal grain is 0.1-0.4 mass%.

Description

  The present invention relates to a Cu-Ni-Si-based copper alloy plate excellent in fatigue resistance and spring characteristics after bending and a method for manufacturing the same, and in particular, as a material for various electronic components, it is a long time after bending into a predetermined shape. The present invention relates to a Cu—Ni—Si based copper alloy having excellent fatigue resistance and spring characteristics even when used under high temperature and high vibration environments, and a method for producing the same.

As electronic devices have become lighter and thinner in recent years, relays, terminals, connectors, etc. are also becoming smaller and thinner, and the copper alloy materials used for them are required to have high strength and bending workability. .
Accordingly, the demand for precipitation-strengthened copper alloys such as corson (Cu—Ni—Si) alloys, beryllium copper and titanium copper is increasing in place of conventional solid solution strengthened copper alloys such as phosphor bronze and brass.
Among them, the Corson alloy is an alloy in which the solid solubility limit of the nickel silicide compound with respect to copper changes remarkably with temperature, and is a kind of precipitation hardening type alloy that hardens by quenching and tempering. Good high-temperature strength, excellent balance between strength and electrical conductivity, widely used in various springs for electric conduction and electric wires for high tensile strength, and recently used in electronic parts such as relays, terminals, connectors, etc. Is growing.
Generally, strength and bending workability are contradictory properties, and in Corson alloys, it has been studied conventionally to improve bending workability while maintaining high strength, adjusting the manufacturing process, crystal grain size, There have been widespread efforts to improve bending workability by controlling the number, shape, and texture of precipitates individually or mutually.
Recently, Cu-Ni-Si based copper has excellent fatigue resistance and spring characteristics even when used in high temperature and high vibration environment for a long time after bending to a predetermined shape as a material for various electronic components. There is a need for alloys.

In Patent Document 1, for the purpose of improving the fatigue characteristics of a Cu—Ni—Si-based alloy, which is a high-strength copper alloy used for electronic materials such as connectors, Ni: 1. It is a copper alloy containing 0 to 4.5%, Si: 0.2 to 1.2%, the balance being Cu and inevitable impurities, and having a compressive residual stress of 20 to 200 MPa on the surface. A characteristic Cu—Ni—Si based alloy is disclosed.
Patent Document 2 discloses a precipitation-strengthening-type copper alloy cold rolled material as a copper alloy sheet suitable for electric and electronic parts with significantly improved bending workability and fatigue characteristics while maintaining high conductivity and strength. By repeatedly bending with a tension leveler, the average hardness Hs (HV) at the 1/8 position in the plate thickness direction and the average hardness Hc (HV) at the 1/2 position in the plate thickness direction are (Hs−Hc) / A copper alloy plate material in which both surface layer portions are softer than the center portion so as to satisfy Hc × 100 ≦ −5 is disclosed, and the alloy composition is, for example, Ni: 0.4 to 4.8% by mass, Si : 0.1-1.2%, if necessary Mg: 0.3% or less or Zn: 15% or less, further Sn, Co, Cr, P, B, Al, Fe, Zr as necessary , Ti, and Mn in a total range of 3% or less, Composition parts substantially C u are mentioned.
Patent Document 3 discloses a Corson (Cu—N—Si) copper alloy plate having a yield strength of 700 N / mm ² or more, an electrical conductivity of 35% IACS or more, and excellent bending workability. This copper alloy plate has Ni: 2.5% (mass%, the same shall apply hereinafter) and less than 6.0%, and Si: 0.5% and less than 1.5%. In the range of 4 to 5, Sn: 0.01% or more and less than 4%, the balance is made of Cu and inevitable impurities, the average crystal grain size is 10 μm or less, and measurement by SEM-EBSP method As a result, after having a texture where the ratio of Cube orientation {001} <100> is 50% or more and obtaining a solution recrystallized structure by continuous annealing, cold rolling with a working rate of 20% or less and 400 to 600 It is manufactured by performing an aging treatment at 1 ° C. for 1 to 8 hours, followed by a short annealing at 400 to 550 ° C. for 30 seconds or less after the final cold rolling at a processing rate of 1 to 20%.

JP 2005-48262 A JP 2007-1000014 A JP 2006-283059 A

Conventional Cu-Ni-Si-based Corson alloys have been improved in bending workability, fatigue resistance, spring characteristics, etc., but bent into a predetermined shape as a material for relay movable pieces and socket terminals of various electronic components. After processing, when used under a high temperature and high vibration environment for a long time, the fatigue resistance and the spring characteristics are insufficient, and there is a defect that the material is not reliable.
The present invention has been made in view of such circumstances, and is used under a high temperature and high vibration environment for a long time after being bent into a predetermined shape as a material such as a relay movable piece or socket terminal of various electronic components. However, an object of the present invention is to provide a Cu—Ni—Si based copper alloy sheet having excellent fatigue resistance and spring characteristics and a method for producing the same.

As a result of intensive studies to solve the above-mentioned problems, the inventors of the present invention contain 1.0 to 3.0% by mass of Ni and have a concentration of 1/6 to 1/4 with respect to the mass% concentration of Ni. In a Cu-Ni-Si based copper alloy plate containing Cu and the inevitable impurities in the balance, copper at a step size of 0.5 μm by the EBSD method using a scanning electron microscope with a backscattered electron diffraction image system When the orientation of all pixels within the measurement area of the surface of the alloy strip is measured, and a boundary where the orientation difference between adjacent pixels is 5 ° or more is regarded as a grain boundary, between all the pixels in the crystal grain The area ratio of the crystal grains whose average misorientation is less than 4 ° is 45 to 55% of the measurement area, and the area average GAM of the crystal grains existing in the measurement area is 0.8 to 1.6 °, N having a particle size of more than 100 nm as measured with an electro-luminescence electron microscope The number of -Si precipitates particles are 0.2 to 0.7 pieces / [mu] m ^2, the concentration of Si in solid solution in the transmission-type crystal grains were measured by an electron microscope is 0.1 to 0.4 It has been found that when it is% by mass, it exhibits excellent fatigue resistance and bending properties after bending.
In addition, by the EBSD method using a scanning electron microscope with a backscattered electron diffraction image system, the orientation of all the pixels within the measurement area of the surface of the copper alloy strip is measured at a step size of 0.5 μm. When the boundary where the orientation difference is 5 ° or more is regarded as a grain boundary, the area average GAM of the crystal grains existing in the measurement area and the solid solution in the crystal grains measured by the transmission electron microscope It has been found that the concentration of Si greatly contributes to the fatigue resistance after bending, and that both of them are within the optimum range, thereby exhibiting excellent fatigue resistance after bending.
In addition, the entire boundary within a crystal grain when a boundary where the orientation difference between adjacent pixels is 5 ° or more measured by an EBSD method using a scanning electron microscope with a backscattered electron diffraction image system is regarded as a crystal grain boundary. The area ratio of crystal grains having an average orientation difference between pixels of less than 4 °, and the number of Ni—Si precipitate particles having a grain diameter of more than 100 nm as measured with an electrolytic emission electron microscope are bent. It was found that the spring characteristics after bending were able to be exhibited by being greatly involved in the later spring characteristics and both being within the optimum range.

  Further, the Cu-Ni-Si-based copper alloy sheet of the present invention is subjected to a process including hot rolling, cold rolling, solution treatment, aging treatment, final cold rolling, tension leveling, and strain relief annealing in this order. When manufacturing the alloy plate, the area average GAM of the crystal grains existing in the above-mentioned measurement area is basically influenced by the temperature and time of the strain relief annealing process, and is dissolved in the above-mentioned crystal grains. The concentration of is basically affected by the temperature and time of the solution treatment process, and the area ratio of the crystal grains in which the average orientation difference between all the pixels in the crystal grains is less than 4 ° is the tension in the tension leveling process. It has been found that the number of Ni—Si precipitate particles having a crystal grain size exceeding 100 nm is influenced by the temperature and time of the aging treatment step.

From these findings, the Cu-Ni-Si-based copper alloy plate excellent in fatigue resistance and spring characteristics after bending according to the present invention contains 1.0 to 3.0 mass% Ni, and the mass of Ni It contains Si at a concentration of 1/6 to 1/4 with respect to the% concentration, the balance is made of Cu and inevitable impurities, and the step size is 0 by the EBSD method using a scanning electron microscope with a backscattered electron diffraction image system. When measuring the orientation of all the pixels within the measurement area of the surface at 5 μm and considering the boundary where the orientation difference between adjacent pixels is 5 ° or more as the grain boundary, between all the pixels in the crystal grain The area ratio of crystal grains having an average misorientation of less than 4 ° is 45 to 55% of the measurement area, and the area average GAM of crystal grains existing in the measurement area is 0.8 to 1.6 °. Yes, the particle size measured with an electrolytic emission electron microscope is 100 nm. The number of excess Ni-Si precipitate particles is 0.2 to 0.7 pieces / [mu] m ^2, the concentration of Si in solid solution in the transmission-type crystal grains were measured by an electron microscope is from 0.1 to 0 .4 mass%.

Ni and Si form fine particles of an intermetallic compound mainly composed of Ni ₂ Si by performing an appropriate heat treatment. As a result, the strength of the alloy is significantly increased and at the same time the electrical conductivity is increased.
Ni is added in the range of 1.0 to 3.0% by mass, preferably 1.5 to 2.5% by mass. If Ni is less than 1.0% by mass, sufficient strength cannot be obtained. When Ni exceeds 3.0 mass%, a hot crack will generate | occur | produce. The addition concentration (mass%) of Si is 1/6 to 1/4 of the addition concentration (mass%) of Ni. If the Si addition concentration is less than 1/6 of the Ni addition concentration, the strength is reduced. If the Si addition concentration is more than 1/4 of the Ni addition concentration, not only does not contribute to the strength, but the conductivity is reduced due to excessive Si.
If the area ratio of the crystal grains in which the average orientation difference between all the pixels in the crystal grains is less than 4 ° is less than 45% or exceeds 55%, a sufficient spring characteristic effect cannot be obtained.
If the area average GAM of the crystal grains present in the measurement area is less than 0.8 °, sufficient fatigue characteristic effects cannot be obtained, and the tensile strength is lowered. If it exceeds 1.6 °, the fatigue property effect will be reduced.
When the number of Ni-Si precipitate particles having a particle size of more than 100 nm is less than 0.2 / μm ² , the tensile strength decreases with a decrease in the spring characteristic effect, and when the number exceeds 0.7 / μm ^2. A sufficient spring characteristic effect cannot be obtained.
If the concentration of Si dissolved in the crystal grains is less than 0.1% by mass, the fatigue property effect decreases and the tensile strength decreases. If it exceeds 0.4% by mass, the fatigue property effect decreases and cracking occurs. Is likely to occur.

Moreover, the Cu—Ni—Si based copper alloy of the present invention may further contain 0.2 to 0.8 mass% of Sn and 0.3 to 1.5 mass% of Zn.
Sn and Zn have an effect of improving strength and heat resistance, Sn has an effect of improving stress relaxation resistance, and Zn has an effect of improving heat resistance of solder joints. Sn is added in the range of 0.2 to 0.8 mass%, and Zn is added in the range of 0.3 to 1.5 mass%. If it is below the above range, the desired effect cannot be obtained, and if it exceeds, the conductivity is lowered.

Furthermore, the Cu—Ni—Si based copper alloy of the present invention may further contain 0.001 to 0.2 mass% of Mg.
Mg has the effect of improving the stress relaxation characteristics and hot workability, but if it exceeds 0.2% by mass, the castability (decrease in casting surface quality), hot workability, and plating heat-resistant peelability deteriorate.

Furthermore, the Cu—Ni—Si based copper alloy of the present invention is further Fe: 0.007 to 0.25 mass%, P: 0.001 to 0.2 mass%, and C: 0.0001 to 0.001 mass. %, Cr: 0.001 to 0.3 mass%, Zr: 0.001 to 0.3 mass%, or one or more of them may be contained.
Fe has the effect of improving the hot rolling property (the effect of suppressing the occurrence of surface cracks and ear cracks) and the effect of minimizing the Ni and Si compound precipitation, thereby improving the plating heat adhesion. Although there is an action to increase the reliability, if the content is less than 0.007%, a desired effect cannot be obtained in the above action. On the other hand, if the content exceeds 0.25%, the hot rolling effect is saturated. However, since the decreasing tendency appears and the conductivity is adversely affected, the content is determined to be 0.007 to 0.25%.
P has an effect of suppressing a decrease in spring property caused by bending, thereby improving an insertion / extraction characteristic of a connector obtained by molding and an effect of improving migration resistance. If the content is less than 001%, the desired effect cannot be obtained. On the other hand, if the content exceeds 0.2%, the heat resistance peelability of the solder is remarkably impaired. %.
C has an effect of improving punching workability, and further has an effect of improving the strength of the alloy by refining a compound of Ni and Si. However, when the content is less than 0.0001%, the desired effect is obtained. On the other hand, if the content exceeds 0.001%, the hot workability is adversely affected. Therefore, the C content is set to 0.0001 to 0.001%.
Cr and Zr have a strong affinity for C and make it easy to contain C in the Cu alloy. In addition, Ni and Si compounds are further refined to improve the strength of the alloy and by precipitation of the alloy itself, the strength is further increased. Although it has an action to improve, even if the content of one or two of Cr and Zr is less than 0.001%, the effect of improving the strength of the alloy cannot be obtained, while it exceeds 0.3% If it is contained, a large precipitate of Cr and / or Zr is generated, which results in poor plating properties, poor punching workability, and further deteriorates hot workability. Therefore, the content of one or two of Cr and Zr is set to 0.001 to 0.3%.

Furthermore, the manufacturing method of the Cu-Ni-Si-based copper alloy sheet having excellent fatigue resistance and spring characteristics after bending according to the present invention includes hot rolling, cold rolling, solution treatment, aging treatment, and final cold. When producing a copper alloy sheet in a process including rolling, tension leveling, and strain relief annealing in this order, solution treatment is performed at 700 to 900 ° C. for 60 to 120 seconds, and aging treatment is performed at 400 to 500 ° C. It is carried out in ˜14 hours, tension leveling is carried out at a tension of 49 to 147 N / mm ² , and strain relief annealing is carried out at 450 to 550 ° C. in 10 to 60 seconds.
By carrying out strain relief annealing at 450 to 550 ° C. for 10 to 60 seconds, the area average GAM of the crystal grains existing in the measurement area becomes within the range of 0.8 to 1.6 °, and the solution treatment is performed. By carrying out at 700 to 900 ° C. for 60 to 120 seconds, the concentration of Si dissolved in the crystal grains is in the range of 0.1 to 0.4% by mass, and excellent resistance to bending after bending. The fatigue characteristics will be exhibited.

When the temperature of strain relief annealing is less than 450 ° C. or when the time is less than 10 seconds, the area average GAM of the grains existing in the measurement area exceeds 1.6 ° and the temperature exceeds 550 ° C. or the time If it exceeds 60 seconds, the area average GAM of the crystal grains becomes less than 0.8 °.
If the solution treatment temperature is less than 700 ° C. or the time is less than 60 seconds, the concentration of Si dissolved in the crystal grains is less than 0.1%, and the temperature exceeds 900 ° C. or the time If it exceeds 120 seconds, the Si concentration exceeds 0.4%.
By carrying out the tension leveling tension at 49 to 147 N / mm ² (5 to 15 kgf / mm ² ), the area ratio of crystal grains having an average orientation difference between all pixels in the crystal grains of less than 4 ° is 45. The number of Ni—Si precipitate particles in which the grain size of the crystal grains existing within the measurement area exceeds 100 nm by performing the aging treatment at 400 to 500 ° C. for 7 to 14 hours within the range of ˜55%. Is in the range of 0.2 to 0.7 pieces / μm ² , and excellent spring characteristics after bending are exhibited.
When the tension of the tension leveling is less than 49 N / mm ² (5 kgf / mm ² ), the area ratio of the crystal grains in which the average orientation difference between all the pixels in the crystal grains is less than 4 ° exceeds 55%, and 147 N / mm ² If it exceeds (15 kgf / mm ² ), the area ratio of crystal grains becomes less than 45%.
When the temperature of the aging treatment is less than 400 ° C. or the time is less than 7 hours, the number of Ni—Si precipitate particles having a grain size exceeding 100 nm in the measurement area is less than 0.2 / μm ^2. When the temperature is 500 ° C. or the time exceeds 14 hours, the number exceeds 0.7 / μm ² .

  According to the present invention, it has excellent fatigue resistance and spring characteristics even when used in a high temperature and high vibration environment for a long time after bending into a predetermined shape as a material for relay movable pieces and socket terminals of various electronic components. A Cu—Ni—Si based copper alloy plate can be obtained.

  Hereinafter, embodiments of the present invention will be described.

[Component composition of copper alloy strip]
The copper alloy strip of the present invention is 1.0% by mass and contains 1.0 to 3.0% by mass of Ni, and contains Si at a concentration of 1/6 to 1/4 with respect to the mass% concentration of Ni. The balance is Cu and inevitable impurities.
Ni and Si form fine particles of an intermetallic compound mainly composed of Ni ₂ Si by performing an appropriate heat treatment. As a result, the strength of the alloy is significantly increased and at the same time the electrical conductivity is increased.
Ni is added in the range of 1.0 to 3.0% by mass, preferably 1.5 to 2.5% by mass. If Ni is less than 1.0% by mass, sufficient strength cannot be obtained. When Ni exceeds 3.0 mass%, a hot crack will generate | occur | produce. The addition concentration (mass%) of Si is 1/6 to 1/4 of the addition concentration (mass%) of Ni. If the Si addition concentration is less than 1/6 of the Ni addition concentration, the strength is reduced. If the Si addition concentration is more than 1/4 of the Ni addition concentration, not only does not contribute to the strength, but the conductivity is reduced due to excessive Si.

Moreover, this copper alloy may contain Sn 0.2-0.8 mass% and Zn 0.3-1.5 mass% further with respect to said basic composition.
Sn and Zn have an effect of improving strength and heat resistance, Sn has an effect of improving stress relaxation resistance, and Zn has an effect of improving heat resistance of solder joints. Sn is added in the range of 0.2 to 0.8 mass%, and Zn is added in the range of 0.3 to 1.5 mass%. If it is below the above range, the desired effect cannot be obtained, and if it exceeds, the conductivity is lowered.

  Moreover, this copper alloy may contain 0.001-0.2 mass% of Mg further with respect to said basic composition. Mg has an effect of improving stress relaxation characteristics and hot workability, and is added in the range of 0.001 to 0.2 mass%. When it exceeds 0.2% by mass, castability (decrease in casting surface quality), hot workability, and plating heat resistance peelability are deteriorated.

Moreover, this copper alloy is further Fe: 0.007-0.25 mass%, P: 0.001-0.2 mass%, C: 0.0001-0.001 mass with respect to said basic composition. %, Cr: 0.001 to 0.3 mass%, Zr: 0.001 to 0.3 mass%, or one or more of them may be contained.
Fe has the effect of improving the hot rolling property (the effect of suppressing the occurrence of surface cracks and ear cracks) and the effect of minimizing the Ni and Si compound precipitation, thereby improving the plating heat adhesion. Although there is an action to increase the reliability, if the content is less than 0.007%, a desired effect cannot be obtained in the above action. On the other hand, if the content exceeds 0.25%, the hot rolling effect is saturated. However, since the decreasing tendency appears and the conductivity is adversely affected, the content is determined to be 0.007 to 0.25%.
P has an effect of suppressing a decrease in spring property caused by bending, thereby improving an insertion / extraction characteristic of a connector obtained by molding and an effect of improving migration resistance. If the content is less than 001%, the desired effect cannot be obtained. On the other hand, if the content exceeds 0.2%, the heat resistance peelability of the solder is remarkably impaired. %.
C has an effect of improving punching workability, and further has an effect of improving the strength of the alloy by refining a compound of Ni and Si. However, when the content is less than 0.0001%, the desired effect is obtained. On the other hand, if the content exceeds 0.001%, the hot workability is adversely affected. Therefore, the C content is set to 0.0001 to 0.001%.
Cr and Zr have a strong affinity for C and make it easy to contain C in the Cu alloy. In addition, Ni and Si compounds are further refined to improve the strength of the alloy and by precipitation of the alloy itself, the strength is further increased. Although it has an action to improve, even if the content of one or two of Cr and Zr is less than 0.001%, the effect of improving the strength of the alloy cannot be obtained, while it exceeds 0.3% If it is contained, a large precipitate of Cr and / or Zr is generated, which results in poor plating properties, poor punching workability, and further deteriorates hot workability. Therefore, the content of one or two of Cr and Zr is set to 0.001 to 0.3%.

[Alloy structure of copper alloy sheet]
The Cu—Ni—Si copper alloy plate of the present invention is measured on the surface of a copper alloy plate at a step size of 0.5 μm by an EBSD method using a scanning electron microscope with a backscattered electron diffraction image system in the alloy structure. When the orientation of all pixels in the area is measured and the boundary where the orientation difference between adjacent pixels is 5 ° or more is regarded as the grain boundary, the average orientation difference between all the pixels in the crystal grain is less than 4 ° The area ratio of the crystal grains is 45 to 55% of the measurement area, the area average GAM of the crystal grains existing in the measurement area is 0.8 to 1.6 °, and an electrolytic emission electron microscope The number of Ni—Si precipitate particles having a measured particle size exceeding 100 nm is 0.2 to 0.7 / μm ² , and the Si particles dissolved in the crystal grains measured with a transmission electron microscope Concentration is 0.1-0.4% by mass, fatigue resistance after bending And it has excellent spring characteristics.

[Area ratio of crystal grains, area average GAM, number of Ni-Si precipitate particles, concentration of Si dissolved in crystal grains]
When the orientation of all pixels within the measurement area of the surface of the copper alloy plate is measured at a step size of 0.5 μm by the EBSD method, and the boundary where the orientation difference between adjacent pixels is 5 ° or more is regarded as a grain boundary The area ratio of the crystal grains in which the average orientation difference between all the pixels in the crystal grains is less than 4 ° was measured as follows.
As a pretreatment, a 10 mm × 10 mm sample taken from a rolled material is immersed in 10% sulfuric acid for 10 minutes, then washed with water and sprinkled by air blow, and then the water sprayed sample is a flat milling (ion milling) device manufactured by Hitachi High-Technologies Corporation. The surface treatment was performed at an acceleration voltage of 5 kV, an incident angle of 5 °, and an irradiation time of 1 hour.
Next, the sample surface was observed with a scanning electron microscope S-3400N manufactured by Hitachi High-Technologies Corporation equipped with an EBSD system manufactured by TSL. The observation conditions were an acceleration voltage of 25 kV and a measurement area of 150 μm × 150 μm (including 5000 or more crystal grains).
From the observation results, the area ratio with respect to the total measurement area of the crystal grains in which the average orientation difference between all the pixels in the crystal grains is less than 4 ° was obtained under the following conditions.
At a step size of 0.5 μm, the orientation of all pixels within the measurement area range was measured, and a boundary where the orientation difference between adjacent pixels was 5 ° or more was regarded as a crystal grain boundary. Next, for each crystal grain surrounded by the crystal grain boundary, an average value (GOS: Grain Orientation Spread) of orientation differences between all the pixels in the crystal grain is calculated by the equation (1), and the average value is 4 The area of the crystal grains of less than 0 ° was calculated and divided by the total measured area, and the ratio of the area of the crystal grains having an average orientation difference within the crystal grains of less than 4 ° to the total crystal grains was determined. In addition, what connected 2 pixels or more was made into the crystal grain.

In the above formula, i and j indicate the numbers of pixels in the crystal grains.
n indicates the number of pixels in the crystal grains.
α _ij represents the difference in orientation between pixels i and j.

The area average GAM of the crystal grains existing within the measurement area was determined as follows.
As a pretreatment, a 10 mm × 10 mm sample taken from a rolled material is immersed in 10% sulfuric acid for 10 minutes, then washed with water and sprinkled by air blow, and then the water sprayed sample is a flat milling (ion milling) device manufactured by Hitachi High-Technologies Corporation. The surface treatment was performed at an acceleration voltage of 5 kV, an incident angle of 5 °, and an irradiation time of 1 hour.
Next, the sample surface was observed with a scanning electron microscope S-3400N manufactured by Hitachi High-Technologies Corporation equipped with an EBSD system manufactured by TSL. The observation conditions were an acceleration voltage of 25 kV and a measurement area of 150 μm × 150 μm (including 5000 or more crystal grains).
From the observation results, the area average GAM of the crystal grains existing within the measurement area was determined under the following conditions.
At a step size of 0.5 μm, the orientation of all pixels within the measurement area range was measured, and a boundary where the orientation difference between adjacent pixels was 5 ° or more was regarded as a crystal grain boundary.
GAM is the average value of misorientation between adjacent measurement points (pixels) in the same crystal grain. When the difference in orientation at the boundary i between adjacent measurement points is expressed by equation (2), the boundary between pixels in the crystal grain is When m exist, the GAM value of this crystal grain is expressed by the equation (3).

When the value of the GAM in individual grains (GAM) _k, the area of each crystal grain and S _k, if there are M grain within the measurement range, area average GAM is expressed by equation (4) The

The number of Ni—Si precipitate particles having a particle diameter exceeding 100 nm and the concentration of Si dissolved in the crystal grains were measured as follows using an electrolytic emission electron microscope.
As a pretreatment, a 10 mm × 10 mm sample was immersed in 10% sulfuric acid for 10 minutes, washed with water and sprinkled with air blow, and the sprinkled sample was accelerating with a flat milling (ion milling) device manufactured by Hitachi High-Technologies Corporation at an acceleration voltage of 5 kV. The surface treatment was performed at an incident angle of 5 ° and an irradiation time of 1 hour.
Next, using an electrolytic emission electron microscope S-4800 manufactured by Hitachi High-Technologies Corp., each point of 10 μm, 30 μm, and 80 μm in depth from the surface of the vertical cross section in the rolling direction of the sample was observed at 20,000 times. The number of Ni—Si precipitate particles having a particle diameter in 100 μm ² exceeding 100 nm was counted and converted to the number / μm ² to obtain the average value.
The concentration of Si dissolved in the crystal grains by a transmission electron microscope was determined as follows.
Using a transmission electron microscope JEM-2010F manufactured by JEOL Ltd., a depth of 10 μm, 30 μm. The concentration of each Si dissolved in the crystal grains at each point of 80 μm was observed, and the average value was obtained.

[Production method]
The method for producing a Cu—Ni—Si based copper alloy of the present invention is a process including hot rolling, cold rolling, solution treatment, aging treatment, final cold rolling, tension leveling, and strain relief annealing in this order. When manufacturing the alloy plate, solution treatment is performed at 700 to 900 ° C. for 60 to 120 seconds, aging treatment is performed at 400 to 500 ° C. for 7 to 14 hours, and the tension leveler tension is 49 to 147 N. / ^mm 2 performed at (5~15kgf / mm ^2), it is carried out in 10 to 60 seconds the strain relief annealing at 450~550 ℃.
By carrying out strain relief annealing at 450 to 550 ° C. for 10 to 60 seconds, the area average GAM of the crystal grains existing in the measurement area becomes within the range of 0.8 to 1.6 °, and the solution treatment is performed. By carrying out at 700 to 900 ° C. for 60 to 120 seconds, the concentration of Si dissolved in the crystal grains is in the range of 0.1 to 0.4% by mass, and excellent resistance to bending after bending. The fatigue characteristics will be exhibited.
When the temperature of strain relief annealing is less than 450 ° C. or when the time is less than 10 seconds, the area average GAM of the grains existing in the measurement area exceeds 1.6 ° and the temperature exceeds 550 ° C. or the time If it exceeds 60 seconds, the area average GAM of the crystal grains becomes less than 0.8 °.
If the solution treatment temperature is less than 700 ° C. or the time is less than 60 seconds, the concentration of Si dissolved in the crystal grains is less than 0.1%, and the temperature exceeds 900 ° C. or the time If it exceeds 120 seconds, the Si concentration exceeds 0.4%.

By carrying out tension of the tension leveler at 49 to 147 N / mm ² (5 to 15 kgf / mm ² ), the area ratio of the crystal grains in which the average orientation difference between all the pixels in the crystal grains is less than 4 ° is 45. The number of Ni—Si precipitate particles in which the grain size of the crystal grains existing within the measurement area exceeds 100 nm by performing the aging treatment at 400 to 500 ° C. for 7 to 14 hours within the range of ˜55%. Is in the range of 0.2 to 0.7 pieces / μm ² , and excellent spring characteristics after bending are exhibited.
When the tension leveler tension is less than 49 N / mm ² (5 kgf / mm ² ), the area ratio of crystal grains in which the average orientation difference between all pixels in the crystal grains is less than 4 ° exceeds 55%, and 147 N / mm ² If it exceeds (15 kgf / mm ² ), the area ratio of crystal grains becomes less than 45%.
When the temperature of the aging treatment is less than 400 ° C. or the time is less than 7 hours, the number of Ni—Si precipitate particles having a grain size exceeding 100 nm in the measurement area is less than 0.2 / μm ^2. When the temperature is 500 ° C. or the time exceeds 14 hours, the number exceeds 0.7 / μm ² .

The following method is mention | raise | lifted as an example of a specific manufacturing method.
First, materials are prepared so as to have the composition of the Cu—Ni—Si based copper alloy plate of the present invention, and melt casting is performed using a low frequency melting furnace in a reducing atmosphere to obtain a copper alloy ingot. Next, after heating this copper alloy ingot to 900 to 980 ° C., it is hot rolled to obtain a hot rolled sheet having an appropriate thickness. After this hot rolled sheet is cooled with water, both sides are appropriately faced, Then, after cold rolling at a rolling rate of 60 to 90% to produce a cold-rolled sheet having an appropriate thickness, continuous annealing is performed at 700 to 800 ° C. for 7 to 15 seconds, and 50 to 50%. Cold rolling is performed at a processing rate of 60% to produce a cold-rolled sheet having an appropriate thickness. Next, after this cold-rolled sheet is held at 700 to 900 ° C. for 60 to 120 seconds and then rapidly cooled and subjected to a solution treatment, it is held at 400 to 500 ° C. for 7 to 14 hours and then subjected to an aging treatment. , After pickling treatment and final cold rolling at a processing rate of 3 to 20%, a plate shape with a tension leveler of 49 to 147 N / mm ² (5 to 15 kgf / mm ² ) Further, strain relief annealing is performed by holding at 450 to 550 ° C. for 10 to 60 seconds to produce a copper alloy plate.

The copper alloy sheet of the present invention thus produced contains 1.0 to 3.0% by mass of Ni, and contains Si at a concentration of 1/6 to 1/4 with respect to the mass% concentration of Ni. The remainder consists of Cu and inevitable impurities, and the orientation of all pixels within the measurement area of the surface of the copper alloy plate with a step size of 0.5 μm by the EBSD method using a scanning electron microscope with a backscattered electron diffraction image system The ratio of the area of the crystal grains in which the average orientation difference between all the pixels in the crystal grains is less than 4 ° when the boundary where the orientation difference between adjacent pixels is 5 ° or more is regarded as the grain boundary. However, it is 45 to 55% of the measurement area, the area average GAM of the crystal grains present in the measurement area is 0.8 to 1.6 °, and the particle diameter measured with an electro-electron emission electron microscope is 100 nm. the number of excess Ni-Si precipitate particles 0.2 to 0.7 pieces / [mu] m And the concentration of Si in solid solution in the transmission-type crystal grains were measured with an electron microscope is 0.1 to 0.4 wt%, have excellent flexural fatigue resistance and spring properties after processing .

Materials are prepared so as to have the components shown in Table 1, and melt casting is performed using a low-frequency melting furnace in a reducing atmosphere to obtain a copper alloy ingot. Next, after heating this copper alloy ingot to 900 to 980 ° C., it is hot rolled to obtain a hot rolled sheet having an appropriate thickness. After this hot rolled sheet is cooled with water, both sides are appropriately faced, Then, after cold rolling at a rolling rate of 60 to 90% to produce a cold-rolled sheet having an appropriate thickness, continuous annealing is performed at 700 to 800 ° C. for 7 to 15 seconds, and 50 to 50%. Cold rolling was performed at a processing rate of 60% to produce a cold-rolled sheet having an appropriate thickness. Next, after the solution treatment was performed under the conditions shown in Table 1, the aging treatment was performed under the conditions shown in Table 1, then the pickling treatment was performed, and the final rate was 3 to 20%. After cold rolling, the copper plate shape was corrected with a tension leveler with the tension shown in Table 1, and further subjected to strain relief annealing under the conditions shown in Table 1, Examples 1 to 10 and Comparative Examples 1 to 9 A copper alloy sheet was prepared.
In Table 1, the tension leveler tension is expressed by N / mm ^{2 in} SI units, and the one by kgf / mm ² is also written in parentheses.

For the samples obtained from the copper alloy plates of Examples 1 to 10 and Comparative Examples 1 to 9, the copper alloy plate at a step size of 0.5 μm by the EBSD method using a scanning electron microscope with a backscattered electron diffraction image system. The average orientation difference between all pixels in a crystal grain when measuring the orientation of all pixels within the measurement area of the surface of the surface and considering the boundary where the orientation difference between adjacent pixels is 5 ° or more as the grain boundary The area ratio of crystal grains having an angle of less than 4 ° and the area average GAM of crystal grains existing within the measurement area were measured. The results are shown in Table 2.
When the boundary where the orientation difference between adjacent pixels is 5 ° or more is regarded as a grain boundary, the area ratio of the crystal grains where the average orientation difference between all the pixels in the crystal grain is less than 4 ° is Measured in the same manner.
As a pretreatment, a 10 mm × 10 mm sample taken from a rolled material is immersed in 10% sulfuric acid for 10 minutes, then washed with water and sprinkled by air blow, and then the water sprayed sample is a flat milling (ion milling) device manufactured by Hitachi High-Technologies Corporation. The surface treatment was performed at an acceleration voltage of 5 kV, an incident angle of 5 °, and an irradiation time of 1 hour.
Next, the sample surface was observed with a scanning electron microscope S-3400N manufactured by Hitachi High-Technologies Corporation equipped with an EBSD system manufactured by TSL. The observation conditions were an acceleration voltage of 25 kV and a measurement area of 150 μm × 150 μm (including 5000 or more crystal grains).
From the observation results, the area ratio with respect to the total measurement area of the crystal grains in which the average orientation difference between all the pixels in the crystal grains is less than 4 ° was obtained under the following conditions.
At a step size of 0.5 μm, the orientation of all pixels within the measurement area range was measured, and a boundary where the orientation difference between adjacent pixels was 5 ° or more was regarded as a crystal grain boundary. Next, for each crystal grain surrounded by the crystal grain boundary, an average value (GOS: Grain Orientation Spread) of orientation differences between all the pixels in the crystal grain is calculated by the equation (1), and the average value is 4 The area of the crystal grains of less than 0 ° was calculated and divided by the total measured area, and the ratio of the area of the crystal grains having an average orientation difference within the crystal grains of less than 4 ° to the total crystal grains was determined. In addition, what connected 2 pixels or more was made into the crystal grain.

In the above formula, i and j indicate the numbers of pixels in the crystal grains.
n indicates the number of pixels in the crystal grains.
α _ij represents the difference in orientation between pixels i and j.

The area average GAM of the crystal grains existing within the measurement area was determined as follows.
As a pretreatment, a 10 mm × 10 mm sample taken from a rolled material is immersed in 10% sulfuric acid for 10 minutes, then washed with water and sprinkled by air blow, and then the water sprayed sample is a flat milling (ion milling) device manufactured by Hitachi High-Technologies Corporation. The surface treatment was performed at an acceleration voltage of 5 kV, an incident angle of 5 °, and an irradiation time of 1 hour.
Next, the sample surface was observed with a scanning electron microscope S-3400N manufactured by Hitachi High-Technologies Corporation equipped with an EBSD system manufactured by TSL. The observation conditions were an acceleration voltage of 25 kV and a measurement area of 150 μm × 150 μm (including 5000 or more crystal grains).
From the observation results, the area average GAM of the crystal grains existing within the measurement area was determined under the following conditions.
At a step size of 0.5 μm, the orientation of all pixels within the measurement area range was measured, and a boundary where the orientation difference between adjacent pixels was 5 ° or more was regarded as a crystal grain boundary.
GAM is the average value of misorientation between adjacent measurement points (pixels) in the same crystal grain. When the difference in orientation at the boundary i between adjacent measurement points is expressed by equation (2), the boundary between pixels in the crystal grain is When m exist, the GAM value of this crystal grain is expressed by the equation (3).

When the value of the GAM in individual grains (GAM) _k, the area of each crystal grain and S _k, if there are M grain within the measurement range, area average GAM is expressed by equation (4) The

Moreover, about the sample obtained from the copper alloy board of Examples 1-10 and Comparative Examples 1-9, the number of the Ni-Si precipitate particle | grains in which a crystal grain diameter exceeds 100 nm, and solid solution in a crystal grain, The concentration (mass%) of Si was measured. The results are shown in Table 2.
The number of Ni—Si precipitate particles having a crystal grain size exceeding 100 nm was measured as follows.
As a pretreatment, a 10 mm × 10 mm sample was immersed in 10% sulfuric acid for 10 minutes, washed with water and sprinkled with air blow, and the sprinkled sample was accelerating with a flat milling (ion milling) device manufactured by Hitachi High-Technologies Corporation at an acceleration voltage of 5 kV. The surface treatment was performed at an incident angle of 5 ° and an irradiation time of 1 hour.
Next, using an electrolytic emission electron microscope S-4800 manufactured by Hitachi High-Technologies Corporation, observations were made at a depth of 10 μm, 30 μm, and 80 μm from the surface of the sample in a vertical cross section in the rolling direction at 20,000 times. in terms of number / [mu] m ² particle size in the 100 [mu] m ² is to count the number of Ni-Si precipitate particles greater than 100 nm, and the average value was calculated.
The concentration of Si dissolved in the crystal grains was determined as follows.
Using a JEM-2010F transmission electron microscope manufactured by JEOL Ltd., each of which is dissolved in crystal grains at a depth of 10 μm, 30 μm and 80 μm from the surface of the sample in the vertical direction in the rolling direction at 50,000 times. The concentration of Si was observed and the average value was determined.

Moreover, about the sample obtained from the copper alloy plate of Examples 1-10 and Comparative Examples 1-9, the fatigue resistance after a bending process and the spring limit value characteristic were measured. The results are shown in Table 2.
The fatigue resistance after bending was determined as follows.
A strip-shaped test piece having a width of 10 mm parallel to the rolling direction was bent at 45 ° with a bending radius R = 0.8 mm perpendicular to the rolling direction (GW) at two locations. The test piece which gave was made, and it performed according to JISZ2273. The test piece was fixed to the fixture so that one of the bent portions was at the fixed end, and the other end was subjected to sinusoidal vibration through a knife edge to determine the fatigue life. The fatigue life (the number of repeated vibrations until the test piece was broken) was measured when the maximum additional stress (stress at the fixed end) on the surface of the test piece was 462 MPa. The measurement was performed four times under the same conditions, and the average value of the four measurements was defined as the fatigue life.

The spring limit value characteristics after bending were obtained as follows.
A strip-shaped test piece having a width of 10 mm parallel to the rolling direction was bent at 45 ° with a bending radius R = 0.8 mm perpendicular to the rolling direction (GW) at two locations. The test piece which gave was made, and it performed according to JISH3130. The test piece is fixed to the fixture so that one of the bent portions is located at the fixed end, and the amount of permanent deflection is measured by a moment type test. T.A. Kb0.1 (surface maximum stress value at the fixed end corresponding to a permanent deflection amount of 0.1 mm: spring limit value) was calculated.

  From the results of Table 1 and Table 2, the Cu—Ni—Si based copper alloy of the present invention is subjected to a high temperature for a long time after bending into a predetermined shape as a material such as a relay movable piece or a socket terminal of various types of electronic components. It can be seen that even when used in a high vibration environment, it has excellent fatigue resistance and spring characteristics.

  As mentioned above, although the manufacturing method of embodiment of this invention was demonstrated, this invention is not limited to this description, A various change can be added in the range which does not deviate from the meaning of this invention.

Claims (5)

It contains 1.0 to 3.0% by mass of Ni, contains Si at a concentration of 1/6 to 1/4 with respect to the mass% concentration of Ni, the balance is made of Cu and inevitable impurities, and backscattered electrons Boundary where the azimuth difference between adjacent pixels is 5 ° or more by measuring the azimuth of all pixels within the measurement area of the surface with a step size of 0.5 μm by the EBSD method using a scanning electron microscope with a diffraction image system , The area ratio of crystal grains in which the average orientation difference between all pixels in the crystal grains is less than 4 ° is 45 to 55% of the measurement area, and within the measurement area The area average GAM of the existing crystal grains is 0.8 to 1.6 °, and the number of Ni—Si precipitate particles having a particle diameter measured by an electro-luminescence emission electron microscope exceeding 100 nm is 0.2 to 0.00. a 7 / [mu] m ^2, binding was measured by a transmission electron microscope Cu-Ni-Si based copper alloy plate excellent in fatigue resistance and spring characteristics after bending, characterized in that the concentration of Si dissolved in the grains is 0.1 to 0.4% by mass .   Furthermore, Sn is contained in an amount of 0.2 to 0.8% by mass and Zn is contained in an amount of 0.3 to 1.5% by mass. Cu-Ni-Si based copper alloy plate.   The Cu-Ni-Si-based copper alloy having excellent fatigue resistance and spring characteristics after bending according to claim 1 or 2, further comprising Mg in an amount of 0.001 to 0.2 mass%. Board.   Furthermore, Fe: 0.007 to 0.25 mass%, P: 0.001 to 0.2 mass%, C: 0.0001 to 0.001 mass%, Cr: 0.001 to 0.3 mass%, Zr The fatigue resistance and spring characteristics after bending according to any one of claims 1 to 3, wherein 0.001 to 0.3% by mass is contained in one kind or two or more kinds. Cu-Ni-Si based copper alloy plate with excellent resistance. A method for producing a copper alloy sheet according to any one of claims 1 to 4, wherein hot rolling, cold rolling, solution treatment, aging treatment, final cold rolling, tension leveling, and strain relief annealing are performed. When producing a copper alloy plate in the process including this order, solution treatment is performed at 700 to 900 ° C. for 60 to 120 seconds, aging treatment is performed at 400 to 500 ° C. for 7 to 14 hours, Excellent fatigue resistance and spring characteristics after bending, characterized in that leveling is performed at a tension of 49 to 147 N / mm ² and strain relief annealing is performed at 450 to 550 ° C. for 10 to 60 seconds. A method for producing a Cu—Ni—Si based copper alloy plate.