JP2017179538A - Copper alloy sheet material and manufacturing method of copper alloy sheet material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a copper alloy sheet material with enhancing especially properties strength, flexure processability, elongation and conductivity at good balance, or the like.SOLUTION: The copper alloy sheet has an alloy component containing 3.0 to 25.0 mass% of Ni and 3.0 to 9.0 mass% of Sn, at least one component selected from a group consisting of 0 to 0.2 mass% of Fe, 0 to 0.05 mass% of Si, 0 to 0.3 mass% of Mg, 0 to 0.5 mass% of Mn, 0 to 0.1 mass% of Zn, 0 to 0.15 mass% of Zr and 0 to 0.1 mas% or P of total 0 to 1.0 mass% and the balance Cu with inevitable impurities, a fine structure shape with varying concentration of solute atom Sn in cycle, difference between maximum and minimum of Sn concentration in a range of 4 to 18 mass% when Sn concentration in a base phase on a (001) surface of crystal particles is surface analyzed and measured, average wavelength of cyclic concentration fluctuation of Sn is 1 nm to 15 nm when measured along (001)[100] orientation and average crystal particle diameter of over 0.1 μm to 6 μm or less.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a copper alloy sheet and a method for producing the copper alloy sheet, and more particularly to an improvement in a copper alloy sheet applied to electrical and electronic parts such as connectors, switches, sockets, and watch parts.

  For example, solid solution strengthened alloys such as phosphor bronze and brass have been used as copper alloy materials used in electrical and electronic parts such as connectors, switches, sockets, and watch parts. However, in recent years, as electronic parts have become significantly lighter, thinner, and shorter, these materials often cannot satisfy the required strength. For this reason, there is an increasing demand for high-strength copper alloys such as high-strength beryllium copper and titanium copper, especially for parts that require high reliability. Titanium copper has low corrosion resistance and is easily corroded by the salt spray test. For example, wearable devices such as smart watches and eyeglass-type terminals that have recently appeared are in contact with the human body. It is unsuitable as a product part that is expected to be used in Japan. Therefore, a Cu—Ni—Sn copper alloy having no toxicity and excellent in strength and corrosion resistance has been attracting attention. Cu-Ni-Sn-based copper alloys are known as age-hardening alloys that improve strength by precipitation of a second phase by aging treatment (for example, Patent Documents 1 to 5).

  In Patent Document 1, for the purpose of adjusting the structure before finishing, a heat treatment at a temperature of 800 ° C. or more that becomes a single phase region and a temperature range of 600 to 770 ° C. at which two phases can appear at room temperature are disclosed. In order to further improve the fatigue characteristics, the heat treatment is performed in a temperature range of 350 to 500 ° C. after the finishing process in the range of 0 to 60%, and the matrix ( By obtaining a structure in which the second phase is uniformly dispersed in the first phase), Cu—Ni— has good formability at low cost and excellent fatigue properties while maintaining mechanical properties and conductivity at a practical level. A method for producing a Sn alloy is described.

  In Patent Document 2, before final finishing, heat treatment at 730 to 770 ° C., rapid cooling, cold work at 55 to 70%, and heat treatment at 400 to 500 ° C. are sequentially performed to form a two-phase region. It describes a Cu—Ni—Sn-based alloy that has been improved in all the properties of tensile strength, 0.2% yield strength, hardness and fatigue strength by heat treatment at temperature.

  Patent Document 3 discloses Ni-Sn having high strength and good bending workability by suppressing the precipitation of second phase particles while reducing the crystal grain size in the solution treatment before the final cold rolling. A copper alloy is described.

  Patent Document 4 includes a step of performing a solution treatment for heating a rolled material at 780 to 900 ° C. and quenching, a step of rolling at a processing rate of 6 to 12%, and an aging treatment for heating at 270 to 400 ° C. And a copper alloy capable of simultaneously obtaining high strength and excellent bending workability by setting the average crystal grain size of the rolled material in a predetermined cross section after solution treatment to less than 6 μm. Yes.

  In Patent Document 5, a solution treatment material is subjected to an aging treatment in a temperature range of 300 ° C. or more and 500 ° C. or less, and then cold working is performed with a processing rate exceeding 60% and 99% or less, and then 300 ° C. A Cu—Ni—Sn alloy in which high-density dislocations are fixed, mechanical strength is further increased, and heat resistance deterioration is suppressed by performing an aging treatment in a temperature range of 500 ° C. or lower is described. .

JP-A-2-88750 JP 2002-266058 A JP 2009-242895 A International Publication No. 2014/016934 Pamphlet International Publication No. 2014/196563 A1 Pamphlet

  By the way, in recent years, along with wearable devices (so-called smart watches) that can be worn on the wrist using a wristwatch system, and mobile devices that are becoming smaller and more functional, parts used are also becoming smaller and the number of parts used is also increasing. There is a need to reduce the thickness of parts that have conventionally used Cu-Ni-Sn alloys to save space, and to develop materials with higher strength and superior bending workability. It has become necessary. According to the prior art, in the heat treatment process, the refinement of the particle size and the number of second phase particles are defined to increase the strength and improve the bending workability. However, the spinodal modulation that is the main component of the strengthening mechanism Since no consideration has been given to the control of the structure, that is, the modulation structure in which the solid solution element concentration periodically varies in the matrix phase, the Cu—Ni—Sn alloy described in Patent Documents 1 to 4 has an appropriate modulation. It did not have a structure. More specifically, in order to optimize the modulation structure, it is necessary to sufficiently dissolve Sn and Ni in the solution forming step. However, in the conventional technique, if the temperature is high enough to sufficiently dissolve, the particle size There is a problem that the bendability is reduced due to coarsening.

  Patent Documents 1 and 2 do not disclose or suggest bending workability, and Patent Document 3 aims to improve the bending workability before aging by suppressing the precipitation of Sn and Ni in the solution treatment process. However, there is no description on bending workability after aging. Further, in Patent Document 4, since Sn and Ni are not sufficiently dissolved in the solution treatment step, there is a high possibility that an appropriate modulation structure is not obtained after aging, and as a result, sufficient strength is not obtained. In addition, since there is no description about elongation, there is no disclosure as to whether it has a balance characteristic between strength and elongation, particularly whether it has sufficient elongation (especially 10% or more). Furthermore, Patent Document 5 examines a spinodal modulation structure, but since periodicity control is not performed, it is unlikely that an appropriate modulation structure is obtained, and two aging treatments are performed. Since cold working is performed at a high working rate, the tensile strength and the 0.2% yield strength are high, but there is a problem that the elongation is low at 5 to 6% and the bending workability is low. Furthermore, all the Cu—Ni—Sn alloy materials described in Patent Documents 1 to 5 have any consideration regarding the balance characteristics between high strength (for example, tensile strength of 900 MPa or more) and high elongation (for example, 10% or more). Since it is not paid, there is a problem that if the elongation is small even if the strength is high, the moldability at the time of processing the parts is lowered.

  The present invention aims to optimize the periodicity and crystal grains of the modulation structure, and to effectively exhibit the characteristics of the modulation structure, thereby improving the strength, bending workability, elongation, and conductivity characteristics in a well-balanced manner. An object of the present invention is to provide an alloy plate material, a connector, and a method for producing a copper alloy plate material.

  A Cu—Ni—Sn alloy is an age-hardening type alloy that improves strength by forming a Sn modulation structure by spinodal decomposition. As a result of intensive studies by the present inventors, a strong spinodal modulation structure after aging is achieved by appropriately controlling each condition of intermediate heat treatment, solution heat treatment, aging heat treatment, and cold rolling performed between these heat treatments. Obtained the knowledge that can be developed into an appropriate structure. Further, the developed modulation structure has a periodicity in the concentration of Sn, which is a solute atom dissolved in a specific direction, and the average wavelength of the periodic concentration fluctuation of Sn when measured along the specific direction. Has been found to be about several nanometers to several tens of nanometers. Further, as the aging temperature increases, the Sn concentration period also increases and the intensity tends to increase, but the average wavelength of the periodic concentration fluctuation of Sn is limited to a range of 1 nm to 15 nm, and Sn By limiting the difference between the maximum value and the minimum value to the range of 4 to 18% by mass, the structure morphology is properly maintained and the strength is increased. In addition, the average crystal grain size is more than 0.1 μm and less than 6 μm. As a result, it was found that bending workability was improved, and as a result, the strength, elongation, bending workability and electrical conductivity could be improved in a balanced manner, and the present invention was completed.

That is, the gist configuration of the present invention is as follows.
(1) Containing 3.0 to 25.0 mass% Ni and 3.0 to 9.0 mass% Sn, and 0 to 0.2 mass% Fe, 0 to 0.05 mass% Si, 0 to 0 .3 mass% Mg, 0-0.5 mass% Mn, 0-0.1 mass% Zn, 0-0.15 mass% Zr and at least one component selected from the group consisting of 0-0.1 mass% P Is a copper alloy sheet having an alloy composition consisting of Cu and unavoidable impurities, and has a fine structure form in which the concentration of solute atoms Sn periodically varies, The difference between the maximum value and the minimum value of the Sn concentration measured by surface analysis of the Sn concentration in the matrix at the (001) plane of the crystal grains is in the range of 4 to 18% by mass, and (001) [ 100] The average wavelength of periodic concentration fluctuations of Sn when measured along the direction is 1 nm or more and 15 nm. Copper alloy sheet, characterized in that a lower and an average grain diameter of 0.1μm ultra 6μm or less.

(2) The copper alloy according to (1) above, wherein the standard deviation of the Sn concentration is 1 to 4% by mass when the Sn concentration in the matrix is measured by plane analysis at the (001) plane of the crystal grains. Board material.

(3) 0.02 to 0.20 mass% Fe, 0.01 to 0.05 mass% Si, 0.01 to 0.30 mass% Mg, 0.01 to 0.50 mass% Mn, 0.01 Containing at least one component selected from the group consisting of ˜0.10 mass% Zn, 0.01 to 0.15 mass% Zr, and 0.01 to 0.10 mass% P in total of 1.0 mass% or less, The copper alloy sheet according to (1) or (2) above.

(4) The copper alloy sheet according to any one of (1) to (3), wherein the tensile strength is 900 MPa or more and the elongation is 10% or more.

(5) The connector which consists of a copper alloy board | plate material of any one of said (1)-(4).

(6) A timepiece part using the copper alloy sheet according to any one of (1) to (4) above.

(7) A method for producing a copper alloy sheet according to any one of (1) to (4) above, wherein the copper alloy sheet is cast into a copper alloy material having an alloy component composition that gives the copper alloy sheet (Step 1). ], Homogenization heat treatment [Step 2], Hot working [Step 3], Face milling [Step 4], First cold working [Step 5], Intermediate heat treatment [Step 6], Second cold working [Step 7] ], Solution heat treatment [Step 8], third cold working [Step 9], and aging treatment [Step 10] are performed in this order, and the intermediate heat treatment is performed at a heating temperature of 300 ° C. to 850 ° C. The holding time is 10 to 300 seconds, the average cooling rate is 100 ° C./second or more, the second cold working has a total working rate of 50 to 90%, and the solution heat treatment has a solution temperature of 650. ˜850 ° C., retention time at the solution temperature of 10 to 300 seconds, and average cooling rate of 100 ° C. The third cold working has a total working rate of 5 to 70%, and the aging treatment has an aging treatment temperature of 300 to 500 ° C. and a holding time at the aging treatment temperature. It is 0.1 to 15 hours, The manufacturing method of the copper alloy board | plate material characterized by the above-mentioned.

  According to the present invention, it contains 3.0-25.0 mass% Ni and 3.0-9.0 mass% Sn, and 0-0.2 mass% Fe, 0-0.05 mass% Si, Selected from the group consisting of 0-0.3 wt% Mg, 0-0.5 wt% Mn, 0-0.1 wt% Zn, 0-0.15 wt% Zr and 0-0.1 wt% P A copper alloy sheet containing at least one component in a total amount of 0 to 1.0 mass%, the balance being an alloy composition composed of Cu and inevitable impurities, and having a fine structure in which the concentration of solute atoms Sn varies periodically And the difference between the maximum value and the minimum value of the Sn concentration when the Sn concentration in the matrix is measured by plane analysis on the (001) plane of the crystal grains is in the range of 4 to 18% by mass ( 001) The average wavelength of periodic concentration fluctuations of Sn when measured along the [100] direction is 1 nm or less. By being 15 nm or less and having an average crystal grain size of more than 0.1 μm and not more than 6 μm, it is possible to provide a copper alloy sheet having particularly improved strength, bending workability, elongation and conductivity characteristics in a well-balanced manner. Became. This copper alloy sheet is suitable for use in electrical and electronic parts and parts such as connectors, switches, sockets, and watch parts. It is particularly suitable for use in parts of devices that require lightweight and corrosion resistance such as smart watches. Moreover, according to the manufacturing method of the copper alloy sheet according to the present invention, the copper alloy sheet can be preferably manufactured.

FIG. 1 shows an observation sample prepared by buffing the surface of a test piece taken from the copper alloy sheet of the present invention to remove an oxide film, and then electropolishing with a 20% nitric acid methanol solution. FIG. 1A shows a diffraction pattern and FIG. 1B shows a TEM photograph when the (001) plane of a crystal grain is observed using a scanning electron microscope (TEM). FIG. 2 is an X-ray diffraction chart of the (200) plane, and shows the displacement Δθ (Δθ ₁ , Δθ ₂ ) of the angle from the main diffraction line of the sideband peak.

Hereinafter, preferred embodiments of the copper alloy sheet of the present invention will be described in detail.
The copper alloy sheet according to the present invention contains 3.0-25.0 mass% Ni and 3.0-9.0 mass% Sn, and 0-0.2 mass% Fe, 0-0.05 mass%. From the group consisting of Si, 0-0.3 wt% Mg, 0-0.5 wt% Mn, 0-0.1 wt% Zn, 0-0.15 wt% Zr and 0-0.1 wt% P A copper alloy sheet material having an alloy composition of 0 to 1.0% by mass in total with at least one component selected, with the balance being Cu and inevitable impurities, wherein the concentration of solute atoms Sn varies periodically The difference between the maximum value and the minimum value of the Sn concentration is 4 to 18% by mass when it has a structural form and is measured by surface analysis of the Sn concentration in the matrix at the (001) plane of the crystal grains. , The average wavelength of the periodic concentration fluctuation of Sn when measured along the (001) [100] direction is And a 1nm or 15nm or less and an average crystal grain diameter of 0.1μm ultra 6μm or less.

  Here, the “copper alloy sheet” in the present invention means that a copper alloy material (having a predetermined alloy composition before processing) has a predetermined shape (for example, a plate, a strip, a foil, a bar, a wire, etc.). It is a processed product, has a specific thickness, is stable in shape and has a spread in the surface direction, and in a broad sense, includes a strip. In the present invention, the thickness of the plate material is not particularly limited, but is preferably 0.05 to 1.0 mm, and more preferably 0.1 to 0.8 mm.

<Ingredient composition>
It shows about a component composition and its effect | action of the copper alloy board | plate material of this invention.

(Essential additive ingredients)
The copper alloy sheet of the present invention contains 3.0 to 25.0 mass% Ni and 3.0 to 9.0 mass% Sn.

[3.0 to 25.0 mass% Ni]
Ni is an important element having the effect of causing spinodal decomposition together with Sn to improve the strength. In order to exhibit such an effect, the Ni content must be 3.0% by mass or more. On the other hand, if the Ni content is more than 25.0% by mass, an intermetallic compound is likely to be generated, and if the generated intermetallic compound remains, it becomes a starting point and cracks occur during cold working. Workability is significantly deteriorated. For this reason, Ni content was made into the range of 3.0-25.0 mass%, Preferably it was 9-20 mass%.

[3.0 to 9.0% by mass Sn]
Sn is an important element having the effect of causing spinodal decomposition together with Ni to improve the strength. In order to exhibit such an effect, the Sn content must be 3.0% by mass or more. On the other hand, if the Sn content is more than 9.0% by mass, an intermetallic compound is likely to be formed, and if the generated intermetallic compound remains, it becomes a starting point and cracks occur during cold working. Workability is significantly deteriorated. For this reason, Sn content was made into the range of 3.0-9.0 mass%, Preferably it was 5-8 mass%.

(Optional additive)
In addition to the essential additive components of Ni and Sn, the copper alloy sheet of the present invention further includes 0.02 to 0.20 mass% Fe, 0.01 to 0.05 mass% Si, 0 as optional additional elements. 0.01 to 0.30 wt% Mg, 0.01 to 0.50 wt% Mn, 0.01 to 0.10 wt% Zn, 0.01 to 0.15 wt% Zr and 0.01 to 0.10 At least one component selected from the group consisting of mass% P can be contained in a total of 1.0 mass% or less.

[0.02 to 0.20 mass% Fe]
Fe is an element having an effect of improving product characteristics such as conductivity, strength, stress relaxation characteristics, and plating properties. In order to exert such an effect, the Fe content needs to be 0.02% or more. However, when the Fe content exceeds 0.20% by mass, the conductivity is greatly reduced and the effect is saturated. For this reason, Fe content shall be 0.02-0.20 mass%.

[0.01-0.05 mass% Si]
Si is an element having an effect of improving the heat-resistant peelability and migration resistance during soldering. In order to exert such an effect, it is necessary to make the Si content 0.01% by mass or more. However, if the Si content exceeds 0.05% by mass, the effect is saturated, and coarse precipitated particles that do not contribute to the strength with Ni may be formed and the strength may be lowered. For this reason, Si content shall be 0.01-0.05 mass%.

[0.01-0.30 mass% Mg]
Mg is an element having an effect of improving stress relaxation characteristics. In order to exert such an effect, it is necessary to make the Mg content 0.01% by mass or more. However, if the Mg content exceeds 0.30% by mass, the electrical conductivity may be greatly reduced, such being undesirable. For this reason, Mg content shall be 0.01-0.30 mass%.

[0.01-0.50 mass% Mn]
Mn is an element having an effect of suppressing the grain boundary reaction type precipitation while improving the rolling workability by dissolving in the matrix. In order to exert such an effect, the Mn content is preferably 0.01% by mass or more, and preferably 0.10 to 0.30% by mass. Further, if Mn is contained in an amount of more than 0.50% by mass, not only the improvement of the effect cannot be expected, but also the conductivity tends to be lowered and the bending workability is adversely affected. For this reason, Mn content shall be 0.01-0.50 mass%.

[0.01-0.10 mass% Zn]
Zn is an element that has the effect of improving the bending workability and improving the adhesion and migration characteristics of Sn plating and solder plating. In order to exert such an effect, the Zn content is preferably 0.01% by mass or more. Moreover, when Zn is contained more than 0.10 mass%, there exists a tendency for electroconductivity to fall. For this reason, Zn content shall be 0.01-0.10 mass%.

[0.01-0.15 mass% Zr]
Zr is an element having an effect of mainly refining crystal grains and improving the strength and bending workability of the copper alloy sheet. In order to exert such an effect, the Zr content is preferably 0.01 mass or more. Moreover, when Zr is contained more than 0.15% by mass, a compound is formed, and there is a tendency that the conductivity and workability such as rolling of a copper alloy sheet are remarkably lowered. For this reason, Zr content shall be 0.01-0.15 mass%.

[0.01-0.10 mass% P]
P is an element having a content of 0.01% by mass or more and having an effect of improving product characteristics such as strength and stress relaxation characteristics without impairing electrical conductivity. However, even if P is contained in an amount of more than 0.10% by mass, not only the effect of improving the properties cannot be expected, but also the compound is molded and the hot workability tends to be lowered. For this reason, P content shall be 0.01-0.10 mass%.

[At least one component selected from the group consisting of Fe, Si, Mg, Mn, Zn, Zr and P is 1.0% by mass or less in total]
The content of at least one component selected from the group consisting of Fe, Si, Mg, Mn, Zn, Zr and P is preferably 1.0% by mass or less in total.
If the content of at least one of the optional addition components is 1.0% by mass or less in total, it is difficult for the workability and conductivity to decrease, so the content of the optional addition component is 1. 0 mass% or less.

<Existence state of solute atoms Sn in the copper alloy sheet (spinodal modulation structure)>
The copper alloy sheet material of the present invention has a fine structure form in which the concentration of solute atoms Sn periodically varies, and the Sn concentration in the matrix is measured by surface analysis at the (001) plane of the crystal grains. The difference between the maximum value and the minimum value of the Sn concentration is in the range of 4 to 18% by mass, and the average wavelength of the periodic concentration fluctuation of Sn when measured along the (001) [100] direction is 1 nm. The average crystal grain size is more than 0.1 μm and not more than 6 μm.

  The inventors of the present invention have made extensive studies to improve the strength, elongation, bending workability and electrical conductivity in a well-balanced manner with respect to Cu—Ni—Sn-based alloys. (I) Intermediate heat treatment, solution heat treatment, aging heat treatment And by appropriately controlling each condition of the cold rolling performed between these heat treatments, the average crystal grain size is fine and a strong spinodal modulation structure after aging can be developed into an appropriate structure. II) In the developed modulation structure, the concentration of Sn, which is a solute atom dissolved in a specific direction, has periodicity, and the average wavelength of the periodic concentration fluctuation of Sn when measured along the specific direction Is about several nanometers to several tens of nanometers, and (III) as the aging temperature increases, the average wavelength of the periodic concentration fluctuations of Sn tends to increase and the intensity tends to increase. Already mentioned above for.

  As a result of further studies by the present inventors, the periodicity of Sn when measured along the (001) [100] direction in a metal structure having an average crystal grain size of more than 0.1 μm and not more than 6 μm. By limiting the average wavelength of the concentration fluctuation to the range of 1 nm or more and 15 nm or less, the strength can be effectively improved, and the Sn concentration in the parent phase is analyzed in the (001) plane of the crystal grains. By limiting the difference between the maximum value and the minimum value of the Sn concentration when measured in the range of 4 to 18% by mass, it is possible to maintain not only high strength and high elongation as a result of maintaining the tissue form properly. It was also found that bending workability and electrical conductivity can be improved in a balanced manner. In addition, the appropriate structure form mentioned here is excellent in bending workability because the average crystal grain size is as fine as more than 0.1 μm and not more than 6 μm, and the difference between the maximum value and the minimum value when the Sn concentration is measured. In the range of 4 to 18% by mass, the presence of Ni—Sn precipitates starting from the grain boundaries indicates a metal structure with improved conductivity.

  In addition, the measuring method of the difference of the maximum value of Sn density | concentration when measuring the Sn density | concentration in a parent phase by surface analysis in the (001) plane of a crystal grain can be performed with the following method. That is, for each test piece, an observation sample was prepared by electropolishing with a methanol solution of 20% nitric acid, and the (001) plane of the crystal grains was observed. Observation was performed using a transmission electron microscope (TEM), and detection (analysis of Sn concentration) was performed using an energy dispersive X-ray spectrometer (EDS) at an electron beam spot diameter of 20 nm. Observation was performed at an observation magnification of 200,000 times, and 5 points were measured at 100 nm intervals in the (001) [100] direction and (001) [010] direction, respectively, and the Sn concentration at a total of 25 points was measured. Was analyzed. In addition, in order to prevent the measurement error by the influence of a precipitate, the position where a precipitate does not exist was selected as a measurement location. And the minimum value and the maximum value were calculated | required from the data of Sn density | concentration measured at 25 measurement locations, and the difference was computed. The same analysis was repeated three times in different observation fields, and the average of them was calculated as a measured value of the difference between the maximum value and the minimum value of the Sn concentration. FIGS. 1A and 1B show an observation sample prepared from the copper alloy sheet of the present invention, and the (001) plane of the crystal grain is observed with a transmission electron microscope (TEM). 1A shows a diffraction pattern, and FIG. 2B shows a TEM photograph. From FIG. 1 (b), it can be seen that there are periodic shades specific to the spinodal modulation structure in the (001) [100] direction. In the present invention, a copper alloy sheet having improved strength, elongation, bending workability, and electrical conductivity in a well-balanced manner can be obtained by defining this light and shade periodicity.

  Moreover, the measuring method of the average wavelength of the periodic concentration fluctuation of Sn can be obtained by an X-ray diffraction method or an electron beam diffraction method. As an example, a case where the average wavelength of the periodic concentration fluctuation of Sn is measured by an X-ray diffraction method will be described below. As the observation sample, the structure was observed using the material after the aging treatment in order to reflect the characteristics in the usage state of the terminal or the like. A 10 mm × 10 mm sample was cut from the plate material, lightly buffed to remove the surface oxide layer, and (200) diffraction sidebands were observed using an X-ray diffractometer. An example of a diffraction chart schematically showing the diffraction lines is shown in FIG. As shown in FIG. 2, for the main diffraction line (200) and the sidebands on both sides thereof, the diffraction angle θ of the main diffraction line, the Miller indices h, k, l of the diffraction line, the lattice constant a, the peak of the sideband. The angle displacement from the main diffraction line is Δθ, and the obtained X-ray sideband is converted to the wavelength λ of the modulation structure (that is, the Sn periodicity) using the Daniel-Lipson equation shown in the following equation (1). Average wavelength of the concentration fluctuation). In the present invention, the Sn structure has a fine structure in which the concentration of Sn periodically varies, and due to this, there is a submaximal on both sides in the vicinity of the main diffraction line (basic reflection) of X-ray diffraction. Diffraction intensity appears. This was used as the X-ray sideband appearing in the alloy of the present invention.

λ = (h · a · tan θ) / {(h ² + k ² + l ² ) · Δθ} (1)

In the case a sideband asymmetry as shown in FIG. 2, the wavelength of the periodic density fluctuation of Sn to the [Delta] [theta] ₂ obtained from the peak of the high angle side is calculated by substituting the above equation (1) λ2 And λ obtained by substituting Δθ ₁ obtained from the peak on the low angle side into the above formula (1) and the wavelength λ1 of the periodic concentration fluctuation of Sn is the average wavelength of the periodic concentration fluctuation of Sn And For example, the average wavelength λ of Sn periodic concentration fluctuations obtained from FIG. 2 is 7.8 nm when the low angle side is 7.1 nm and the high angle side is 8.5 nm.

  In addition, when measuring the average wavelength of the Sn periodic concentration fluctuations by the electron diffraction method, as in the case of the X-ray sideband, the Daniel-Lipson equation is used to calculate the Sn from the electron beam satellite. The average wavelength λ of periodic concentration fluctuations may be calculated.

  Moreover, in this invention, it is preferable that the standard deviation of Sn density | concentration when the Sn density | concentration in a parent phase is measured by surface analysis in the (001) plane of a crystal grain is 1-4 mass%. If the standard deviation of the Sn concentration is less than 1% by mass, the change in the Sn concentration is too small, so that the effect of improving the strength is not exhibited. If the Sn deviation exceeds 4% by mass, the change in the Sn concentration becomes too large and the coarse Since the two-phase particles are likely to precipitate, the strength and bending workability may be reduced. In addition, the calculation method of the standard deviation of Sn concentration can be performed by calculating from the data of Sn concentration of 25 points obtained from the measurement conditions described above.

  The average crystal grain size of the copper alloy sheet is required to be more than 0.1 μm and not more than 6 μm. If the average crystal grain size is 0.1 μm or less, the recrystallized structure tends to be a mixed grain (a structure in which crystal grains having different sizes are mixed), and there is a tendency for bending workability and stress relaxation characteristics to decrease, This is because if it is larger than 6 μm, the bending workability tends to decrease. The crystal grain size was measured based on the crystal grain size measurement method (cutting method) defined in JIS H0501-1986, and three arbitrarily selected locations were photographed, and the crystal was calculated from a 1000 × photograph. Average value of particle diameter.

[Method for producing copper alloy sheet]
Next, the preferable manufacturing method of the copper alloy sheet | seat material of this invention is demonstrated.
The copper alloy plate material of the present invention contains 3.0 to 25.0 mass% Ni and 3.0 to 9.0 mass% Sn, and further optionally contains Fe, Si, Mg, Mn, Zn, Zr and P are appropriately contained, and a copper alloy material having an alloy composition consisting of Cu and inevitable impurities is prepared, and this copper alloy material is cast [step 1], homogenized heat treatment [step 2]. ], Hot working [step 3], chamfering [step 4], first cold working [step 5], intermediate heat treatment [step 6], second cold working [step 7], solution heat treatment [step 8]. ], 3rd cold work [process 9], and an aging treatment [process 10] are performed in this order. In particular, for producing the copper alloy sheet of the present invention, intermediate heat treatment [Step 6], second cold working [Step 7], solution heat treatment [Step 8], third cold working [Step 9] and aging treatment It is preferable to strictly manage each condition of [Step 10].

  The raw materials of Cu, Ni, and Sn are melted and cast in a caster, for example, a carbon crucible (inner wall), preferably made of carbon [step 1]. The atmosphere inside the casting machine when melting is preferably a vacuum or an inert gas atmosphere such as nitrogen or argon in order to prevent the formation of oxides. There is no restriction | limiting in particular in a casting method, For example, a horizontal type continuous casting machine, an up-cast method, etc. can be used. Since the solidified segregation and crystallized matter generated during the ingot is coarse, it is desirable to make it as small as possible by dissolving it in the parent phase as much as possible by the homogenization heat treatment [Step 2]. This is because it is effective in preventing bending cracks. Specifically, after the casting process, it is preferable to heat to 800 to 1000 ° C. and perform a homogenization heat treatment for 1 to 24 hours, and then perform hot working [step 3]. Although the hot working after the homogenization heat treatment can be omitted, for example, it may be performed at a processing temperature of about 850 ° C. and a processing degree of 50% or more. The chamfering step is performed in order to remove the oxide film and the altered layer on the skin of the copper alloy sheet. This can be done by a generally known method. In addition, about hot processing, there is no restriction | limiting in particular in either rolling processing or extrusion processing.

After the hot working, the surface is chamfered [Step 4], and the first cold working [Step 5] is performed. The processing rate of the first cold processing is preferably 70% or more. When the processing method is rolling, the processing rate R (%) is defined by the following equation (2).
R = (t ₀ −t) / t ₀ × 100 (2)
In the formula, t ₀ is a plate thickness before rolling, and t is a plate thickness after rolling.

  The copper alloy sheet of the present invention is an intermediate heat treatment in which the heating temperature is 300 to 850 ° C., the holding time is 10 to 300 seconds, and the average cooling rate is 100 ° C./second or more between the first cold working and the solution heat treatment [ Subsequent to step 6], the second cold working [step 7] with a total working rate of 50 to 90% is performed. In the intermediate heat treatment, by performing the heat treatment at a temperature lower than the solution heat treatment temperature, it is possible to obtain a subannealed structure in which the material is not completely recrystallized but partially recrystallized. In the second cold working, microscopically non-uniform strain can be introduced into the material by rolling at a working rate of 90% or less. By introducing these two steps, it is possible to sufficiently dissolve Sn at the time of solution heat treatment and to suppress recrystallized grain growth, while maintaining fine crystal grains sufficiently by aging treatment. As a result of the formation of a modulation structure of solid solution Sn, high strength can be obtained. A more preferable range of the intermediate heat treatment is a heating temperature of 600 to 750 ° C. and a holding time of 15 to 45 seconds. A more preferable range of the total processing rate of the second cold processing is 55 to 85%, and a more preferable range is 60 to 80%.

  Conventionally, heat treatment such as the intermediate heat treatment has been performed in order to reduce the strength by recrystallizing the material in order to reduce the load in the next process. The purpose of rolling is to reduce the plate thickness, and if the capability of a normal rolling mill, it is common to employ a processing rate exceeding 90%. The purpose of performing the intermediate heat treatment and the second cold working in the present invention is to have a significant modulation structure periodicity of the Sn concentration distribution, unlike these general contents.

  Next, after the second cold working, a solution heat treatment having a solution temperature of 650 to 850 ° C., a holding time at the solution temperature of 10 to 300 seconds, and an average cooling rate of 100 ° C./second or more [Step 8] I do. In the solution heat treatment, necessary temperature conditions vary depending on the concentrations of Ni and Sn. Therefore, it is necessary to select appropriate temperature conditions according to the concentrations of Ni and Sn. When the solution temperature is 650 ° C. or higher, sufficient strength is obtained in the aging treatment step, and when the solution temperature is 850 ° C. or lower, the material is not softened more than necessary and the shape control is appropriately performed. Can do.

  After the solution treatment, 5 to 70% of the third cold working [Step 9] is performed. This third cold working is performed in order to increase the strength by introducing dislocations by working and also to increase the strength after aging. When cold working at this working rate is performed, the Sn concentration distribution is within the scope of the present invention. It is preferable. The third cold working also contributes to the improvement of strength by work hardening. If it is less than 5%, the desired strength cannot be obtained after aging, and if the processing rate exceeds 70%, no further strength can be expected, but the bending workability deteriorates.

  After the third cold working, an aging treatment [Step 10] is performed in which the aging treatment temperature is 300 to 500 ° C. and the holding time at the aging treatment temperature is 0.1 to 15 hours. When the aging treatment temperature is 300 ° C. or higher, spinodal decomposition is promoted and sufficient strength is obtained, and when the aging treatment temperature is 500 ° C. or less, precipitates are not coarsened and the strength is maintained. . In the present invention, unlike the prior art, since the crystal grain size is fine by solution treatment and Sn is sufficiently dissolved, the spinodal decomposition is promoted by aging, and the strength of the obtained copper alloy sheet material Can be improved.

  Further, after the aging treatment, finish cold working and low temperature annealing may be performed as necessary. In this case, the finish cold working is preferably performed at a working rate of 0 to 20% or less, and the low temperature annealing is preferably performed at 200 to 400 ° C. for 5 seconds to 3 hours.

<Characteristics of copper alloy sheet>
When the copper alloy sheet of the present invention is used as an electrical / electronic component such as a connector, it is preferable that the tensile strength is 900 MPa or more and the elongation is 10% or more.

  Hereinafter, the present invention will be described in more detail based on examples, but the present invention is not limited thereto.

(Examples 1-13 and Comparative Examples 1-17)
First, a copper alloy having the alloy composition shown in Table 1 was melted by a DC (Direct Chill) method and cast to obtain an ingot having a thickness of 30 mm, a width of 100 mm, and a length of 150 mm. Next, these ingots were heated to 900 ° C. for homogenization treatment, maintained at this temperature for 1 hour, hot-rolled to a thickness of 14 mm, and quickly cooled. Next, both sides were chamfered by 1 mm each to remove the oxide film, and then cold rolled at a processing rate of 90 to 98% as the first cold working. Thereafter, an intermediate heat treatment was performed under the conditions shown in Table 2, and cold rolling with a processing rate of 80% was performed as the second cold working. Thereafter, solution heat treatment was performed under the conditions shown in Table 2. Next, cold rolling was performed at a processing rate shown in Table 2 as the third cold processing. Next, various characteristics evaluations were performed using a copper alloy sheet material that was produced by aging treatment under the conditions shown in Table 2 in an inert gas atmosphere.

  With respect to the copper alloy plate thus produced, the following tests and evaluations were carried out using samples cut from the copper alloy plate after the aging treatment in both the examples and the comparative examples. In addition, when measuring along the (001) [100] direction, the difference between the maximum value and the minimum value of the Sn concentration when the Sn concentration in the matrix is measured by plane analysis at the (001) plane of the crystal grain The average wavelength of the periodic fluctuations of the Sn concentration, the standard deviation of the Sn concentration and the measurement of the average crystal grain size when the Sn concentration in the parent phase is measured on the (001) plane of the crystal grains, and About the characteristic evaluation regarding the intensity | strength of a copper alloy board | plate material, elongation, a bending characteristic, and electrical conductivity, it performed by the following method.

1. Calculation method of difference and standard deviation of maximum and minimum values of Sn concentration measured by surface analysis of Sn concentration in parent phase on (001) plane of crystal grains Methanol with 20% nitric acid for each test piece An observation sample was prepared by electrolytic polishing with a solution, and the (001) plane of the crystal grains was observed. Observation was performed using a transmission electron microscope (TEM), and detection (analysis of Sn concentration) was performed using an energy dispersive X-ray spectrometer (EDS) at an electron beam spot diameter of 20 nm. Observation was performed at an observation magnification of 200,000 times, and 5 points were measured at 100 nm intervals in the (001) [100] direction and (001) [010] direction, respectively, and the Sn concentration at a total of 25 points was measured. Was analyzed. In addition, in order to prevent the measurement error by the influence of a precipitate, the position where a precipitate does not exist was selected as a measurement location. And the minimum value and the maximum value were calculated | required from the data of Sn density | concentration measured at 25 measurement locations, and the difference was computed. The same analysis was repeated three times in different observation fields, and the average of them was calculated as a measured value of the difference between the maximum value and the minimum value of the Sn concentration. The standard deviation of the Sn concentration was calculated from the Sn concentration data of 75 points (25 points in each of three observation fields) obtained from the measurement conditions described above. Table 1 shows the measured value of the difference between the maximum value and the minimum value of the Sn concentration and the calculated value of the standard deviation.

2. (001) Measurement of average wavelength of periodic concentration fluctuation of Sn when measured along [100] direction The measurement method of the average wavelength of periodic concentration fluctuation of Sn is an X-ray diffraction method or an electron beam diffraction method. It can ask for. For example, the case where the average wavelength of the periodic fluctuation of the Sn concentration is measured by the X-ray diffraction method will be described below. As the observation sample, the structure was observed using the material after the aging treatment in order to reflect the characteristics in the usage state of the terminal or the like. A 10 mm × 10 mm sample was cut from the plate material, lightly buffed to remove the surface oxide layer, and a (200) diffraction sideband was observed using an X-ray diffractometer. An example of a diffraction chart schematically showing the diffraction lines is shown in FIG. As shown in FIG. 2, for the main diffraction line (200) and the sidebands on both sides thereof, the diffraction angle θ of the main diffraction line, the Miller indices h, k, l of the diffraction line, the lattice constant a, the peak of the sideband. The angle displacement from the main diffraction line is Δθ, and the obtained X-ray sideband is converted to the wavelength λ of the modulation structure (that is, the Sn periodicity) using the Daniel-Lipson equation shown in the following equation (1). Average wavelength of the concentration fluctuation). Table 1 shows the average wavelength of the periodic concentration fluctuation of Sn.
λ = (h · a · tan θ) / {(h ² + k ² + l ² ) · Δθ} (1)

3. Grain size measurement method After the cross section perpendicular to the rolling direction of the test piece was polished into a mirror surface by wet polishing and buffing, the polished surface was corroded with a solution of chromic acid: water = 1: 1 for several seconds, A photograph was taken at a magnification of 400 to 1000 times using a secondary electron image, and the average crystal grain size (μm) of the cross section was measured according to the cutting method of JIS H0501-1986. The cross section was measured by a cross section in the rolling direction. Table 1 shows the average crystal grain size.

4). Tensile strength Three test pieces of JIS Z2201-13B cut out in the rolling parallel direction of the test material (test piece) were measured according to JIS Z2241: 2011, and the average value is shown in Table 3.

5). Elongation Three were measured according to JIS Z 2241: 2011, and the average value (%) is shown in Table 3.

6). Bending workability W. A strip sample having a width of 10 mm and a length of 50 mm is prepared in the direction, and the ratio of the bending radius R (mm) to the thickness t (mm) (R / t) = 1 in the W bending test (JIS H3130: 2012). The appearance of the bent convex surface is compared with the evaluation standard according to Japan Copper and Brass Association Standard JBMA T307: 1999, and “O” indicates that no cracks occur, and “X” indicates that cracks occur as “bad”. Is shown in Table 3.

7). Conductivity Conductivity is measured by measuring the conductivity of two test pieces in a thermostatic chamber controlled at 20 ° C. (± 1 ° C.) using a four-terminal method based on JIS H0505-1975. Values (% IACS) are shown in Table 3. At this time, the distance between terminals was set to 100 mm.

  From the results shown in Table 3, in each of Examples 1 to 13, the maximum value and the minimum value of the Sn concentration when the Sn concentration in the parent phase was measured by surface analysis on the (001) plane of the alloy composition and crystal grains. Since the average wavelength of the difference in value and the periodic concentration fluctuation of Sn when measured along the (001) [100] direction is within the appropriate range, the tensile strength is 1039 to 1423 MPa and 900 MPa or more, and the elongation is Is 10% or more of 10 to 30%, the conductivity is 5.4 to 14.1% IACS, and the bending workability is also good, all of tensile strength, elongation, conductivity and bending workability It can be seen that the above characteristics are satisfied at a high level in a balanced manner.

  On the other hand, in all of Comparative Examples 1 to 17, the difference between the maximum value and the minimum value of the Sn concentration when the alloy composition and the Sn concentration in the parent phase were measured by plane analysis on the (001) plane of the crystal grains. , And the average wavelength of the periodic concentration fluctuation of Sn when measured along the (001) [100] orientation, since at least one is outside the proper range, the tensile strength is as low as 490-883 MPa and less than 900 MPa. Moreover, all of Comparative Examples 4 to 9, 11, 13, and 16 have a low elongation of less than 10%, and Comparative Examples 1, 2, 5, 6, 8, 9, 11, 14, and 16 are all From the fact that bending workability is inferior, it can be seen that none of Comparative Examples 1 to 17 can satisfy all properties of tensile strength, elongation, conductivity and bending workability at a high level in a balanced manner.

  According to the present invention, it has become possible to provide a copper alloy sheet having improved strength, bending workability, elongation and electrical conductivity in a well-balanced manner. In particular, this copper alloy sheet is suitable for use in electrical and electronic parts and parts such as connectors, switches, sockets, and watch parts. It is particularly suitable for use in parts of devices that require lightweight and corrosion resistance such as smart watches. Moreover, according to the manufacturing method of the copper alloy sheet according to the present invention, the copper alloy sheet can be preferably manufactured.

Claims (7)

Contains 3.0 to 25.0 mass% Ni and 3.0 to 9.0 mass% Sn, and 0 to 0.2 mass% Fe, 0 to 0.05 mass% Si, 0 to 0.3 mass % Mg, 0 to 0.5 mass% Mn, 0 to 0.1 mass% Zn, 0 to 0.15 mass% Zr and 0 to 0.1 mass% P. It is a copper alloy plate material having an alloy composition containing 0 to 1.0 mass%, the balance being Cu and inevitable impurities,
It has a fine structural form in which the concentration of solute atoms Sn varies periodically,
The difference between the maximum value and the minimum value of the Sn concentration when the Sn concentration in the matrix is measured by plane analysis at the (001) plane of the crystal grains is in the range of 4 to 18% by mass,
(001) The average wavelength of Sn periodic concentration fluctuation when measured along the [100] orientation is 1 nm or more and 15 nm or less, and the average crystal grain size is more than 0.1 μm and 6 μm or less. Copper alloy sheet material.   2. The copper alloy sheet according to claim 1, wherein the standard deviation of the Sn concentration is 1 to 4 mass% when the Sn concentration in the matrix is measured by surface analysis at the (001) plane of the crystal grains.   0.02 to 0.20 mass% Fe, 0.01 to 0.05 mass% Si, 0.01 to 0.30 mass% Mg, 0.01 to 0.50 mass% Mn, 0.01 to 0. 0. The composition contains at least one component selected from the group consisting of 10 mass% Zn, 0.01-0.15 mass% Zr, and 0.01-0.10 mass% P in total of 1.0 mass% or less. Or the copper alloy plate material of 2.   The copper alloy sheet according to any one of claims 1 to 3, wherein the tensile strength is 900 MPa or more and the elongation is 10% or more.   The connector which consists of a copper alloy board | plate material of any one of Claims 1-4.   A timepiece part using the copper alloy sheet according to any one of claims 1 to 4. A method for producing a copper alloy sheet according to any one of claims 1 to 4,
Casting [Step 1], homogenization heat treatment [Step 2], hot working [Step 3], chamfering [Step 4], first cold working to a copper alloy material having an alloy component composition that gives the copper alloy sheet material [Step 5], intermediate heat treatment [Step 6], second cold working [Step 7], solution heat treatment [Step 8], third cold working [Step 9], and aging treatment [Step 10] are performed in this order. ,
The intermediate heat treatment has a heating temperature of 300 ° C. to 850 ° C., a holding time at the heating temperature of 10 to 300 seconds, and an average cooling rate of 100 ° C./second or more,
The second cold working has a total working rate of 50 to 90%,
The solution heat treatment has a solution temperature of 650 to 850 ° C., a holding time at the solution temperature of 10 to 300 seconds, and an average cooling rate of 100 ° C./second or more,
The third cold working has a total working rate of 5 to 70%, and
In the aging treatment, the aging treatment temperature is 300 to 500 ° C., and the holding time at the aging treatment temperature is 0.1 to 15 hours.