JP2005089843A - High-strength copper alloy sheet and manufacturing method therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a Corson alloy having adequate bendability, a tensile strength as high as 900 MPa or higher, and an electroconductivity of 20% IACS or higher. <P>SOLUTION: The copper alloy sheet comprises 4.0-5.0 mass% Ni, and Si so that a mass ratio Ni/Si of Ni to Si can be in a range of 4 to 5, and the balance substantially copper with unavoidable impurities; includes such Ni<SB>2</SB>Si precipitates (A) with grain sizes (d) of which the average is 3 to 10 nm and with spaces (l) among them of which the average 25 nm or less, in a structure of the copper alloy sheet after having been artificially aged, when the structure of the copper alloy sheet is observed by using a transmission electron microscope with a magnification of million times; and has the tensile strength of 900 MPa or higher and the electroconductivity of 20% IACS or higher. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a copper alloy having high strength, high conductivity, and excellent bending workability, and relates to a high-strength copper alloy plate for electrical and electronic parts suitable for automobile connectors and the like, and a method for producing a high-strength copper alloy plate. .

  With the demand for downsizing and weight reduction of electronic devices, downsizing and weight reduction of electric / electronic parts are progressing. And in order to reduce the size and weight of these electrical / electronic components, the copper alloy materials used for them are also reduced in thickness and width, and in the case of IC, the copper alloy plate is as thin as 0.1 to 0.15 mm. Are also being used. As a result, copper alloy materials used for these electric / electronic parts are required to have higher tensile strength. For example, high strength copper alloy plates of 900 MPa or more are required for automobile connectors and the like.

  In addition, the copper alloy plates used for connectors, terminals, switches, relays, lead frames, etc. must be subjected to severe bending workability such as 90 ° bending after notching as well as the high strength and high conductivity. There are many more. In addition, along with the downsizing of electronic components, conventionally, severe bending work is usually performed with a bend line perpendicular to the rolling direction (so-called GW), but it is usually performed with a bend line parallel to the rolling direction. (So-called B.W.) is increasing.

  Further, the tendency of the electric and electronic parts to become thinner and narrower reduces the cross-sectional area of the conductive portion of the copper alloy material. In order to compensate for the decrease in conductivity due to the reduction in the cross-sectional area, the copper alloy material itself is required to have a good conductivity of 20% IACS or more.

  Conventionally, 42 alloy (Fe-42 mass% Ni alloy) is known as a high-strength copper alloy material. This 42 alloy has a tensile strength of about 580 MPa, little anisotropy, and good bending workability. However, this 42 alloy cannot meet the demand for higher strength of 900 MPa or more. In addition, 42 alloy contains a large amount of Ni, and therefore has a problem of high price.

For this reason, the Corson alloy (Cu-Ni-Si system) which is excellent in the above-mentioned various properties and is inexpensive has come to be used for electric / electronic parts. This Corson alloy is an alloy in which the solubility limit of nickel silicide compound (Ni ₂ Si) in copper changes significantly with temperature. It is a kind of precipitation hardening type alloy that hardens by quenching and tempering. It has good strength and has been widely used for various conductive springs and high tensile strength electric wires.

  However, even in this Corson alloy, when the strength of the copper alloy material is improved, the conductivity and the bending workability are also lowered. That is, in a high-strength Corson alloy, it is a very difficult task to achieve good conductivity and bending workability.

  As a high-strength copper alloy having excellent bending workability, Ni: 2 to 5 wt%, Si: 0.5 to 1.5 wt%, Zn: 0.1 to 2 wt%, Mn: 0.01 to 0.1 wt. Corson alloys have been proposed that contain the following elements: Cr, 0.001 to 0.1 wt%, Al; 0.001 to 0.15 wt%, Co; 0.05 to 2 wt%, and the content of S as an impurity component is regulated to 15 ppm or less. (See Patent Document 1).

Further, as a copper alloy having excellent bending workability, Ni: 2 to 4% by weight, Si: 0.5 to 1.0% by weight, Zn: 0.1 to 1.0% by weight, Al; 0.001 to 0.15% by weight, Mn: 0.01 to 0.1% by weight %, Cr; 0.001 to 0.1% by weight, S; 0.002% by weight or less, the balance being a copper alloy substantially composed of copper and inevitable impurities, the size of the precipitate being 10 nm or less, A Corson alloy having a distribution density of precipitates of 1 × 10 ⁵ pieces / (μm ³ ) or more and a hardness Hv of 220 or more has also been proposed (see Patent Document 2).

  Furthermore, as a copper alloy plate having excellent bending workability, Ni: 0.4 to 5%, Si: 0.1 to 1%, the balance Cu and inevitable impurities, parallel and perpendicular to the rolling direction Corson alloy having a yield strength of 450 N / mm 2 or more, a ratio of yield strength to tensile strength of 0.95 or less, a ratio of uniform elongation to total elongation of 0.5 or more, and an n value of 0.05 or more. Has been proposed (see Patent Document 3).

Japanese Patent No. 3049137 (pages 1, 6-10) JP-A-6-184680 (pages 1, 5-7) JP 2002-266042 A (pages 1, 6-7)

  However, even in these improved Corson alloys, when the strength of the copper alloy material is improved, the conductivity and bending workability are also lowered. In particular, if the tensile strength of 900 MPa or more is to be given, the conductivity is inevitably lowered to a level of less than 20% IACS.

  For example, in Patent Document 1, even the highest Corson alloy having a tensile strength of about 916 MPa has a conductivity of only about 26.3% IACS. In addition, it contains Al that lowers the conductivity, Cr that lowers the castability, and the productivity is poor, and it is difficult to stably obtain a copper alloy plate having high strength and high conductivity. In Patent Document 2, the conductivity of the Corson alloy having the highest tensile strength of about 892 MPa is about 44% IACS. In Patent Document 3, the highest Corson alloy having a tensile strength of about 710 to 730 MPa has a conductivity of about 46% IACS.

  That is, from these facts, a high strength copper alloy for electrical and electronic parts having a tensile strength of 900 MPa or more cannot achieve high electrical conductivity, and the electrical conductivity is set to 20% IACS or more and good bending It can be seen that securing workability is a very difficult task.

  The present invention has been made to solve such problems, has a high strength having a tensile strength of 900 MPa or more, and has an electrical conductivity of 20% IACS or more and good bending workability. It is to provide a Corson alloy having

In order to achieve this object, the gist of the high-strength copper alloy sheet of the present invention is as follows: Ni: 4.0 to 5.0% by mass, and Si is a mass ratio of Ni to Si Ni / Si is in the range of 4 to 5. A copper alloy plate that is substantially composed of copper and unavoidable impurities, and the copper alloy plate after artificial age hardening treatment was observed with a transmission electron microscope of 1 million times. The average particle size of Ni ₂ Si precipitates present in the copper alloy sheet structure is 3 to 10 nm, the average interval of Ni ₂ Si precipitates is 25 nm or less, and the tensile strength of the copper alloy sheet The strength is 900 MPa or more, and the conductivity is 20% IACS or more.

In order to achieve the above object, the summary of the method for producing a high-strength copper alloy of the present invention includes Ni: 4.0 to 5.0% by mass, and Si has a mass ratio of Ni to Si of Ni / Si of 4 to 4 The copper alloy rolled sheet is included so that the balance is substantially composed of copper and unavoidable impurities, and the balance is substantially composed of copper and unavoidable impurities. Perform an artificial age hardening treatment after cold rolling, or repeat the process of cold rolling and artificial age hardening treatment twice or more to obtain a copper alloy sheet. When observing the copper alloy sheet structure, the average particle size of the Ni ₂ Si precipitates present in the copper alloy sheet structure is 3 to 10 nm and the average interval between the Ni ₂ Si precipitates is 25 nm or less. The tensile strength of the plate is 900 MPa or more, and the conductivity is 20% IACS or more.

  In the present invention, the combination of the specific component composition of the copper alloy plate and the structure specified under the specific observation condition has a high strength having a tensile strength of 900 MPa or more, and a conductivity of 20%. It is possible to provide a Corson-based copper alloy sheet having an IACS or higher and good bending workability.

  In addition, by using the above specific manufacturing method, the structure of the corson-based copper alloy plate subjected to artificial age hardening treatment can be a structure specified under the above specific observation conditions, and the tensile strength is 900 MPa or more. Further, the electrical conductivity can be 20% IACS or more, and the bending workability can be excellent.

  At this time, it is preferable that the copper alloy plate and the copper alloy plate obtained by the specific manufacturing method have higher strength and higher conductivity. Accordingly, the tensile strength is preferably 930 MPa or more, more preferably 950 MPa or more. The conductivity is preferably 30% IACS or more, more preferably 40% IACS or more.

(Ni ₂ Si precipitate)
The Ni ₂ Si precipitate referred to in the present invention is a precipitate of A shown in FIGS. 1 and 2 which is a transmission electron microscope (TEM) photograph of 1 million times the copper alloy plate of the present invention described later. This refers to fine Ni ₂ Si precipitates having an average particle size of 3 to 10 nm, which are present in the copper alloy sheet structure after age hardening. The Ni ₂ Si precipitate A shown in FIGS. 1 and 2 appears in the shape of a white line having a width, crossing the elliptical black spot.

This Ni ₂ Si precipitate is formed by the Ni, Si once dissolved in the copper structure by the solution treatment under specific conditions during the production of the high strength copper alloy sheet of the present invention. Ni ₂ Si phase (compound phase) finely precipitated from the phase.

However, the Ni ₂ Si phase present in the copper alloy sheet structure after the artificial age hardening treatment is already present before the artificial age hardening treatment, in addition to the fine Ni ₂ Si precipitate, and even after the artificial age hardening treatment. There is also a Ni ₂ Si phase present. The Ni ₂ Si phase that already exists before the artificial age hardening treatment is mainly a crystallized substance that already exists at the ingot stage in the production of the copper alloy sheet. Including the crystallized product, the Ni ₂ Si phase that already exists before the artificial age hardening treatment and remains after the artificial age hardening treatment is a coarse particle having a particle size of about several tens of μm or more. It cannot be observed with the specified transmission electron microscope with a magnification of 1 million times. In other words, the transmission electron microscope observation conditions of 1 million times specified in the present invention are specific conditions for observing only the Ni ₂ Si phase newly precipitated from the mother phase by artificial age hardening treatment under specific conditions. It can be said that.

(Copper alloy sheet structure conditions)
In the copper alloy sheet structure of the present invention, the average particle size of Ni ₂ Si precipitates present in the artificial age-hardened copper alloy sheet structure is 3 to 10 nm, and the average interval of Ni ₂ Si precipitates is 25 nm. It is defined as follows.

FIGS. 1 and 2 show tissue photographs taken at the magnification of 1,000,000, respectively, taken under the transmission electron microscope structure observation conditions of the present invention. FIG. 1 is a structural photograph of Invention Example 3 in Table 2 of Examples described later, and FIG. 2 is a structural photograph of Comparative Example 17 in Examples described later. In the figures 1, 2, A represents Ni ₂ Si precipitates, d is the particle diameter of the Ni ₂ Si precipitates (nm), l respectively denote an interval of Ni ₂ Si precipitates (nm).

In the present invention, the particle size d of the precipitate refers to the length of the white line (long side or longest side) of the Ni ₂ Si precipitate as shown in FIGS. Then, those each particle diameter d of each Ni ₂ Si precipitates A in the observation field of view was averaged, the average particle size referred to in the present invention.

In the present invention, the interval 1 between Ni ₂ Si precipitates means the interval 1 between adjacent Ni ₂ Si precipitates A 1 and A ₂ in the observation field, as shown in FIGS. However, in the calculation, the average interval l _AV. Referred to in the present invention is obtained from the number n of Ni ₂ Si precipitates A present in the unit volume V. _{That, l AV. = V / n} , l AV. = 3 obtained from √ (V / n).

Here, the unit volume V is the volume of the sample for observation, and is obtained as x nm ³ from the size of the sample, length (nm) × width (nm) × film thickness (nm). Therefore, the average distance l _AV of the Ni ₂ Si precipitates _A. Is the volume V of the sample for observation (x nm ^3), from the measurement number n of present in the visual field Ni ₂ Si precipitates A, ₃ √ ( x / n).

Fine Ni that contributes to high strength, high bending work, and high conductivity by setting the above average particle size of the Ni ₂ Si precipitate in the structure of artificial age-hardened copper alloy sheet to 3 to 10 nm ₂ The amount (number) of Si precipitates can be increased. Based on the transmission electron microscope observation conditions inherent to the present invention described above, the fine Ni ₂ Si precipitate referred to here is substantially newly precipitated from the parent phase by artificial age hardening treatment under specific conditions. Ni ₂ Si phase.

When the average particle size of Ni ₂ Si precipitates exceeds 10 nm, the amount (number) of fine Ni ₂ Si precipitates contributing to high strength is insufficient. For this reason, the tensile strength of the copper alloy plate cannot be increased to 900 MPa or more, and the electrical conductivity cannot be achieved. On the other hand, if the average particle size of Ni ₂ Si precipitates is made smaller than 3 nm, the Ni ₂ Si precipitates are cut by dislocations, so the tensile strength of the copper alloy sheet cannot be increased to 900 MPa or more. Incompatible with conductivity. Therefore, the average particle size of the Ni ₂ Si precipitates present in the artificial age-hardened copper alloy sheet structure is in the range of 3 to 10 nm.

In addition, the tensile strength of the copper alloy sheet can be increased to 900 MPa or more by reducing the average distance between the Ni ₂ Si precipitates in the artificial age-hardened copper alloy sheet structure to 25 nm or less. When the average interval between Ni ₂ Si precipitates exceeds 25 nm, the tensile strength of the copper alloy sheet cannot be increased to 900 MPa or more, and the electrical conductivity cannot be achieved. Therefore, the average interval between Ni ₂ Si precipitates is defined as 25 nm or less.

The Ni ₂ Si phase present in the copper alloy sheet structure after the artificial age hardening treatment is already present before the artificial age hardening treatment, in addition to the fine Ni ₂ Si precipitate, and after the artificial age hardening treatment. It is preferable to reduce the Ni ₂ Si phase present as much as possible. The Ni ₂ Si phase already present before such artificial age hardening treatment is coarse with a particle size of about several tens of μm or more as described above, and does not contribute to improvement in strength. Further, when Ni or Si is consumed in these Ni ₂ Si phases, the amount of the fine Ni ₂ Si precipitates generated after the artificial age hardening treatment and contributing to improvement in strength and bending workability is reduced.

However, due to limitations in casting technology, it is not possible to eliminate the Ni ₂ Si phase that already exists before the artificial age hardening treatment and exists after the artificial age hardening treatment. Therefore, the copper alloy sheet in tissue after artificial aging treatment in the present invention allows a mix of these coarse Ni ₂ Si phase. In other words, in the present invention, the Ni ₂ Si phase that already exists before the artificial age hardening treatment and also exists after the artificial age hardening treatment is present (mixed) in the copper alloy sheet structure after the artificial age hardening treatment. However, there is an advantage that the tensile strength of the copper alloy sheet can be increased to 900 MPa or more, the conductivity can be increased to 20% IACS or more, and the bending workability can be compatible.

(Conditions for observation of copper alloy sheet structure)
In transmission electron microscope observation with a magnification lower than the ultrahigh magnification of 1 million times defined in the present invention, Ni ₂ which already exists before the artificial age hardening treatment including the crystallized substance and remains after the artificial age hardening treatment. There is a possibility that the Si phase will be confused and observed. In addition, the Ni ₂ Si phase itself may not be identified or observed.

FIGS. 3 and 4 show, for example, 150,000 times transmission electron microscope observation results of Corson alloy plates having Ni of 3.9% and 4.4%, respectively. As can be seen from FIGS. 3 and 4, it is difficult to systematically distinguish the dislocations introduced into the copper alloy sheet structure by cold rolling of the copper alloy sheet from the Ni ₂ Si phase. In particular, as the cold rolling ratio increases, the amount of dislocations introduced into the copper alloy sheet structure increases, making it difficult to observe the structure of the finely precipitated Ni ₂ Si phase with a transmission electron microscope. In this regard, unless the transmission electron microscope with the ultra-high magnification of 1 million times defined in the present invention is used, it is difficult to distinguish between dislocations and finely precipitated Ni ₂ Si phases as shown in FIGS. 3 and 4 above. Become.

  The preferred structure observation conditions with a transmission electron microscope other than the above magnification will be described below. The film thickness of the sample in the transmission electron microscope is preferably 1 to 100 nm. When the film thickness of the observation sample exceeds 100 nm, a sufficiently clear tissue image cannot be obtained.

On the other hand, when the film thickness of the observation sample is less than 1 nm, the number of Ni ₂ Si precipitates observed is smaller. For this reason, it is easy to observe especially the average interval more than the actual, and the performance of the actual copper alloy sheet is compatible with both high strength with a tensile strength of 900 MPa or more and high conductivity with a conductivity of 20% IACS or more. Despite this, it is easy to misunderstand that organizational conditions are not satisfied.

Other conditions, for example, the accelerating voltage of the transmission electron microscope does not affect much between 100 and 300 kV, but it is preferable to keep it constant at 200 kV. In observation of Ni ₂ Si precipitates with a transmission electron microscope, it is possible to appropriately select whether to perform image processing on a tissue screen magnified 1 million times or to visually observe a photograph.

In Patent Document 2, the size of the precipitate is defined as 10 nm or less, and the distribution density of the precipitate is defined as 1 × 10 ⁵ pieces / (μm ³ ) or more. Patent Document 2 discloses that a Corson alloy, which is a precipitation hardening type alloy, is affected by the distribution state of Ni ₂ Si precipitates (intermetallic compounds), that is, the size and distance (interval) of the precipitates. . Then, in Patent Document 2, with less Ni ₂ Si phase already already present before artificial aging, such as crystallized substances present at the stage of the ingot, Ni ₂ Si to be newly deposited in artificial aging Trying to increase the number of phases. Specifically, by reducing the size and distance of Ni ₂ Si precipitates newly deposited by this artificial aging treatment, the strength is improved while maintaining good bending workability.

  Nevertheless, in Patent Document 2, the Corson alloy having a conductivity of about 44% IACS has a tensile strength of at most about 892 MPa, and a tensile strength of 900 MPa or more is not obtained. Also, it is impossible to achieve both high conductivity of 35% or more and high strength of 900 MPa or more.

The reason is considered that the structure observation by the transmission electron microscope described in the example of Patent Document 2 is not 150,000 times the ultra high magnification defined in the present invention but 150,000 times as low. That is, in the structure observation with a transmission electron microscope having a lower magnification such as 150,000 times, as described above, it is not possible to accurately observe only the Ni ₂ Si phase newly precipitated from the mother phase by the artificial age hardening treatment. Therefore, Patent Document 2 does not accurately define the ideal Ni ₂ Si phase for achieving both high conductivity of 20% or more and high strength of 900 MPa or more.

Further, since the Ni content in Patent Document 2 is relatively low, at most about 4% by weight, the amount of Ni ₂ Si phase newly precipitated by artificial aging treatment is inevitably reduced. As a result, in Patent Document 2, the Ni ₂ Si phase already existing before the artificial aging treatment such as the crystallized material already existing at the ingot stage is reduced, and Ni ₂ newly precipitated by the artificial aging treatment is reduced. Despite attempts to increase the Si phase, the structure of the actual copper alloy sheet after artificial aging treatment is thought to be a structure with less fine Ni ₂ Si phase newly precipitated by artificial aging treatment. It is done. For this reason, the tensile strength of the copper alloy plate cannot be stably increased to 900 MPa or higher, or the electrical conductivity cannot be increased to 20% or higher even if the tensile strength is increased.

(Component composition of copper alloy sheet)
Below, the reason for limitation of the chemical component composition in this invention copper alloy board, such as making the copper alloy board structure | tissue after artificial age hardening processing into the structure | tissue of the said this invention provision is demonstrated.

(Ni; 4.0-5.0%)
Ni is an element that is essential in addition to Si, which will be described later, and forms a Ni ₂ Si phase precipitated by artificial aging treatment, thereby contributing to the improvement of the strength of the copper alloy sheet. When the Ni content is less than 4.0%, the Ni ₂ Si phase is insufficient, and the tensile strength of the copper alloy sheet cannot be 900 MPa or more. On the other hand, if the Ni content exceeds 5.0%, the electrical conductivity decreases, and the electrical conductivity of the copper alloy sheet cannot be made 20% IACS or more. Furthermore, castability and bending workability in casting are deteriorated. Therefore, the Ni content is in the range of 4.0 to 5.0%.

(Si)
Si is also an essential element together with Ni, and forms an Ni ₂ Si phase precipitated by artificial aging treatment, thereby contributing to improvement of the strength of the copper alloy sheet. However, in order to make the conductivity of the copper alloy plate as high as possible as 20% IACS or more and the tensile strength of the copper alloy plate to be 900 MPa or more, the Ni and Si are within the range of the content of each other. In the above, it is necessary that the Ni and Si are included in an equivalent amount necessary for forming the Ni ₂ Si phase. When this is expressed by the mass ratio Ni / Si between Ni and Si, it is in the range of 4 to 5 close to the composition ratio of Ni ₂ Si. Therefore, the content of Si is expressed by a mass ratio Ni / Si between Ni and Si.

If Ni and Si are excessively contained outside this range, the tensile strength of the copper alloy plate can be 900 MPa or more, but the excess Ni or Si is dissolved in the copper matrix. In addition, the conductivity of the copper alloy plate is reduced. Moreover, when Si is contained excessively, the castability in casting and the hot and cold rolling processes are also lowered, and casting cracks and rolling cracks are likely to occur. On the other hand, if it is out of this range and the Si content is too small, the Ni ₂ Si phase is insufficient and the tensile strength of the copper alloy sheet cannot be made 900 MPa or more.

(Other alloy elements)
The high-strength copper alloy sheet of the present invention is, as other alloy elements, in mass%, Sn: 0.1-4.0%, Zn: 0.1-1.0%, Ag: 0.001-1.0%, Mn: 0.01-0.1%, Zr: 0.001 One or two or more of -0.1% and Co: 0.01-0.3% can be contained selectively or as required. All of these elements are synergistic elements having a common effect of improving any one of the main purposes of the copper alloy of the present invention, strength, conductivity, and bending workability. Below, the characteristic effect of each element and the significance of the content range are described.

(Sn: 0.1-4.0%)
Sn is an element mainly improving the strength of the copper alloy sheet, and is selectively contained when used for applications in which these characteristics are important. If the Sn content is less than 0.1%, the strength improving effect is not obtained. On the other hand, when Sn is contained, the electrical conductivity of the copper alloy plate is lowered. In particular, if Sn is contained in excess of 4.0%, the conductivity of the copper alloy sheet cannot be made 20% IACS or more. Therefore, when it contains, content of Sn shall be 0.1 to 4.0% of range.

(Zn: 0.1 to 1.0%)
Zn is an element mainly improving the releasability and migration resistance of solder, and is selectively contained when used for applications in which these characteristics are important. If the Zn content is less than 0.1%, there is no effect. On the other hand, if Zn is contained, the electrical conductivity of the copper alloy plate is lowered, and if Zn is contained in excess of 1.0%, the electrical conductivity of the copper alloy plate cannot be 20% IACS or more. Therefore, when it is contained, the Zn content is in the range of 0.1 to 1.0%.

(Ag: 0.001 to 1.0%)
Ag mainly improves conductivity. Therefore, when it is desired to improve the electrical conductivity, it is selectively contained. If the Ag content is less than 0.001%, the effect is not obtained. On the other hand, even if Ag is contained in excess of 1.0%, the cost increases significantly due to expensive Ag. Therefore, when contained, the content of Ag is set to a range of 0.001 to 1.0%.

(Mn: 0.01-0.1%)
Mn mainly improves the workability in hot rolling. Therefore, when it is desired to improve hot workability, it is selectively contained. If the Mn content is less than 0.01%, the effect is not obtained. On the other hand, if Mn is contained in an amount exceeding 0.1%, the hot metal flowability at the time of agglomeration of the copper alloy deteriorates and the agglomeration yield decreases. Therefore, when it is contained, the Mn content is in the range of 0.01 to 0.1%.

(Zr: 0.001 to 0.1%)
Zr mainly refines the crystal grains and improves the strength and bending workability of the copper alloy sheet. Therefore, when it is desired to improve strength and bending workability, it is selectively contained. If the Zr content is less than 0.001%, the effect is not obtained. On the other hand, when Zr is contained in an amount exceeding 0.1%, a compound is formed and workability such as rolling of a copper alloy sheet is lowered. Therefore, when it is contained, the Zr content is in the range of 0.001 to 0.1%.

(Co: 0.01-0.3%)
Co mainly refines crystal grains to improve the strength and bending workability of copper alloy sheets. Therefore, when it is desired to improve strength and bending workability, it is selectively contained. If the Co content is less than 0.01%, the effect is not obtained. On the other hand, when Co exceeds 0.3%, a compound is formed and workability such as rolling of a copper alloy sheet is lowered. Therefore, when it contains, content of Co shall be 0.01 to 0.3% of range.

  As other elements, Al, Cr, Fe, Ti, P, Be, V, Nb, Mo, W, Mg, and the like are impurities that deteriorate the characteristics of the copper alloy plate. However, if the total content of these is up to 0.5% by mass, the characteristics of the high-strength copper alloy sheet of the present invention are not impaired. Therefore, the inclusion of these alloy elements within the above range is allowed.

  In the high-strength copper alloy plate of the present invention, particularly, impurities to be regulated include B, C, Na, S, Ca, As, Se, Cd, In, Sb, Pb, Bi, MM (Misch metal), etc. Can be given. These impair the castability, hot workability, or the characteristics of the high-strength copper alloy sheet. Therefore, the content of these impurities is restricted as much as possible. More specifically, the total amount is limited to 0.1% by mass, and the content is made as low as possible.

  Next, preferable manufacturing conditions such as making the copper alloy sheet structure after the artificial age hardening treatment the structure defined in the present invention will be described below. The manufacturing process itself of the copper alloy sheet of the present invention does not require any special process, and can be manufactured by the same process as that of a conventional method. That is, a molten metal containing 4.0% to 5.0% of Ni and 4.0% to 5.0% of Si and 0.5% to 1.5% of the balance, with the balance being substantially copper and unavoidable impurities, and further adding the selective additive elements to adjust the components. Cast. Then, after chamfering the ingot, it is heated or homogenized and then hot-rolled, and the hot-rolled plate is water-cooled. After that, primary cold rolling, which is said to be intermediate rolling, is annealed and washed as necessary, and further finish cold-rolled to obtain a copper alloy plate having a product thickness.

Before and after finish cold rolling (usually before finish cold rolling), a solution treatment of the copper alloy plate and a quenching treatment by water cooling are performed. At this time, the solution treatment temperature is selected from a range of 750 to 1000 ° C., but is preferably a relatively high temperature of 880 to 920 ° C. At a low solution treatment temperature, such as less than 880 ° C, as described above, the Ni ₂ Si phase already present before the artificial age hardening treatment such as the crystallized product is completely dissolved by heating during the solution treatment. However, it may remain as it is and may be mixed in the copper alloy plate after the artificial age hardening treatment. In addition, as the Ni ₂ Si phase already present before the artificial aging treatment, a considerable amount of Ni ₂ Si is consumed in advance, and the amount of newly precipitated Ni ₂ Si phase is inevitably reduced in the artificial aging treatment. . On the other hand, if the solution treatment temperature exceeds 920 ° C., burning problems are likely to occur, which may be disadvantageous in terms of manufacturing costs.

Of the cold rolling, the finishing cold rolling is preferably as high as possible. Specifically, in order to increase the strength of the copper alloy sheet and to secure the precipitation amount and fine precipitation of Ni ₂ Si precipitates, it is preferable that the finish cold rolling process rate be 20% or more. If the finish cold rolling processing rate is less than 20%, it is not possible to expect a high strength copper alloy sheet due to work hardening (high deposition of introduced dislocations by the Orowan mechanism). In addition, the amount of Ni ₂ Si precipitates deposited by artificial age hardening is reduced. Furthermore, there is a possibility that the size of the Ni ₂ Si precipitate deposited by the artificial age hardening treatment becomes coarse. As a result, there is a possibility that the copper alloy sheet cannot have both a tensile strength of 900 MPa or more, a conductivity of 20% IACS or more, and a high bending process.

Artificial age hardening after cold rolling plays a role in precipitating fine Ni ₂ Si precipitates that contribute to high strength, high bending work, and high electrical conductivity. At this time, it is important that the average particle size of the Ni ₂ Si precipitates existing in the artificial age-hardened copper alloy sheet structure is 3 to 10 nm and the average interval of the Ni ₂ Si precipitates is 25 nm or less. It is.

  For this reason, the conditions for artificial age hardening treatment are selected from the temperature range of 350 to 550 ℃ and the treatment range of 2 to 6 hours so that the tensile strength of the copper alloy sheet is 900 MPa or higher or close to the highest value. Is done. The Corson alloy having the composition of the present invention has a peak in which the tensile strength of the copper alloy sheet is maximum within the range of conditions for the artificial age hardening treatment. The temperature and time of the artificial age hardening treatment that causes this peak value vary depending on the component composition of the copper alloy sheet. Therefore, a condition that makes the maximum value or the maximum value of the tensile strength of the specific copper alloy sheet is selected from the range of the temperature and time of the artificial age hardening treatment. At a temperature and time outside this peak, the tensile strength is greatly reduced compared to the peak value, and the tensile strength of the copper alloy sheet of 900 MPa or more cannot be increased.

However, it is preferable that the processing temperature is selected from the range of 430 to 480 ° C. and the processing time is selected from the range of 3 to 5 hours from the viewpoint of setting the tensile strength of the copper alloy sheet to 900 MPa or more. When out of the range the preferred temperature range and treatment time, in relation to the component range, the average distance between the average particle size and / or Ni ₂ Si precipitate Ni ₂ Si precipitates, can satisfy the present invention defined The possibility of disappearing is increased. For this reason, there is a high possibility that high strength, high bending work, and high conductivity cannot be achieved at the same time.

The series of steps of the finish cold rolling and the artificial age hardening after cold rolling may be repeated not only once but twice or more. In this case, the cold work rate can be further increased, and the above-mentioned finish cold rolling has the advantage that the copper alloy sheet can be strengthened, the amount of Ni ₂ Si precipitates deposited and the fine precipitation ensured. There is.

  Examples of the present invention will be described below. Copper alloy sheets were produced by casting copper alloys having the respective compositions shown in Table 1 below, and each characteristic was evaluated. In addition, in the copper alloy plates having the respective compositions shown in Table 1, as elements other than those described in Table 1, Al, Cr, Fe, Ti, P, Be, V, Nb, Mo, W, and Mg are those The total amount was 0.5% by mass or less. Further, the total amount of elements such as B, C, Na, S, Ca, As, Se, Cd, In, Sb, Pb, Bi, and MM (Misch metal) was 0.1% by mass or less.

  A specific method for producing a copper alloy sheet is to melt in a kryptor furnace in the atmosphere under charcoal coating and cast into a cast iron book mold to form an ingot having a thickness of 50 mm, a width of 75 mm, and a length of 180 mm. Obtained. Then, after chamfering the surface of the ingot, it was hot-rolled at a temperature of 950 ° C. to a thickness of 15 mm, and rapidly cooled into water from a temperature of 750 ° C. or higher. Next, after removing the oxide scale, primary cold rolling was performed to obtain a plate having a thickness of 0.7 mm.

  Subsequently, using a salt bath furnace, a solution treatment was performed by heating for 30 seconds in common at the temperatures shown in Tables 2 and 3, and then rapidly cooled in water. Next, by cold-rolling finishes, each of the thicknesses was in the range of 0.20 mm (processing rate 70%) to 0.6 mm (processing rate 10%), and the processing rate was changed into cold rolled sheets. As shown in Tables 2 and 3, this cold-rolled sheet was subjected to artificial age hardening treatment at different temperatures (° C.) and times (hr).

  With respect to the copper alloy plate thus produced, in each example, the test and evaluation shown below were performed using a sample cut out from the copper alloy plate after the artificial age hardening treatment.

  The average particle size (size: nm) and average interval (nm) of the precipitates were measured from the structure photograph taken at the magnification of 1,000,000 times according to the transmission electron microscope structure observation conditions of the present invention described above and the calculation method described above. Calculated. Structure photographs of Invention Example 3 and Comparative Example 17 shown in Table 2 are shown in FIGS. 1 and 2, as described above, A represents a precipitate, d represents a particle size (nm) of the precipitate, and B represents an interval (nm) between the precipitates.

  The tensile test was carried out using this test piece by cutting out in parallel with the rolling direction to prepare a JIS No. 13 test piece.

  The conductivity was calculated by an average cross-sectional area method using a test piece having a width of 10 mm and a length of 300 mm, measuring the electric resistance with a double bridge.

The bending workability was R = 0.15 mm in an actual press, the bending line was set parallel (BW) and right angle (GW) to the rolling direction, and 90 ° bending was performed. And the bending part was observed with the magnifier of 20 times, and bending workability was evaluated by the presence or absence of generation | occurrence | production of a crack. That is, even if there were no cracks in the bent part and the bending process conditions were strict, those having good bending workability were evaluated as “good”. In addition, there are no large cracks, but there are small cracks. If the bending conditions are relaxed, the bending is possible. Δ. Large cracks are present, and even if the bending conditions are relaxed, bending is not possible. Each was rated as x.
These test results are also shown in Tables 2 and 3 below. Table 2 shows invention examples, and Table 3 shows comparative examples.

As is apparent from Tables 1 and 2, an example of the invention within the inventive composition containing Ni; 4.0 to 5.0% by mass, and containing Si so that the mass ratio Ni / Si of Ni to Si is in the range of 4 to 5 Invention Examples 1 to 14 using Alloys 1 to 10 are manufactured under preferable conditions for the manufacturing method. For this reason, as shown in FIG. 1 of the example 3 of the invention, the copper alloy plate structure after the artificial age hardening treatment was observed in the copper alloy plate structure when the copper alloy plate structure was observed with a transmission electron microscope of 1 million times. The average particle size of the Ni ₂ Si precipitates present is 3 to 10 nm, and the average interval between the Ni ₂ Si precipitates is 25 nm or less. As a result, the tensile strength of the copper alloy sheet after the artificial age hardening treatment is 900 MPa or more, and the conductivity is 20% IACS or more. Inventive Examples 1 to 14 are also excellent in bending workability.

On the other hand, as is clear from Tables 1 and 3, in Comparative Example 15, the content of Ni in Comparative Alloy Example 11 used was within the range but was excessive with respect to Si, and Ni / Si exceeded 5 . For this reason, although the manufacturing method is manufactured within preferable conditions, the average interval of Ni ₂ Si precipitates exceeds 25 nm, and the tensile strength of the copper alloy sheet after artificial age hardening is less than 900 MPa.

In Comparative Example 16, the Si of Comparative Alloy Example 12 used is excessive with respect to Ni, and Ni / Si is less than 4. Therefore, the manufacturing method is manufactured in the preferred conditions, although the average distance between the average particle diameter and the Ni ₂ Si precipitate Ni ₂ Si precipitates are also within the scope of the copper alloy plate after the artificial age hardening treatment Conductivity is less than 20% IACS. Also, bending workability is low.

In Comparative Example 17, the Ni content of Comparative Alloy Example 13 used is too small. Therefore, although the manufacturing method is manufactured within preferable conditions, the average particle size of the Ni ₂ Si precipitate exceeds 10 nm and the average interval exceeds 25 nm, and the tensile strength of the copper alloy sheet after artificial age hardening treatment Is less than 900MPa.

  In Comparative Example 18, the Ni content of Comparative Alloy Example 14 used is too large. For this reason, although the manufacturing method is manufactured under preferable conditions, the electrical conductivity of the copper alloy sheet after the artificial age hardening treatment is less than 20% IACS. Also, bending workability is low.

In Comparative Example 19, the Si content of Comparative Alloy Example 15 used is too large, and Ni / Si is more than 5. Therefore, although the manufacturing method is manufactured within preferable conditions, the average particle size of the Ni ₂ Si precipitate exceeds 10 nm and the average interval exceeds 25 nm, and the tensile strength of the copper alloy sheet after artificial age hardening treatment Is less than 900MPa.

In Comparative Example 20, the Si content of Comparative Alloy Example 16 used was too small, and Ni / Si was less than 4. Therefore, the manufacturing method is manufactured in the preferred conditions, although the average distance between the average particle diameter and the Ni ₂ Si precipitate Ni ₂ Si precipitates are also within the scope of the copper alloy plate after the artificial age hardening treatment Conductivity is less than 20% IACS. Also, bending workability is low.

Comparative Example 21 uses Inventive Alloy Example 2, but the solution treatment temperature is too low, the average particle size of Ni ₂ Si precipitates is the upper limit of 10 nm, the average interval exceeds 25 nm, and the artificial age hardening treatment The tensile strength of the later copper alloy sheet is less than 900 MPa.

Comparative Example 22 uses Inventive Alloy Example 2, but the finish cold rolling rate is too low, the solution treatment temperature is too low, the average interval of Ni ₂ Si precipitates exceeds 25 nm, and the artificial age hardening treatment The tensile strength of the later copper alloy sheet is less than 900 MPa.

Comparative Example 23 and 24, but using the invention alloy Example 2, by artificial age hardening treatment temperature is too high, with an average particle size of the Ni ₂ Si precipitates exceeds 10 nm, the average distance between the Ni ₂ Si precipitate Exceeds 25nm. As a result, the tensile strength of the copper alloy sheet after the artificial age hardening treatment is a remarkably low value of less than 900 MPa.

Comparative Example 25 and 26, but using the invention alloy Example 2, the average artificial age hardening treatment temperature is too low, with an average particle size of the Ni ₂ Si precipitates is less than 3 nm, the Ni ₂ Si precipitate The interval exceeds 25 nm. As a result, the tensile strength of the copper alloy sheet after the artificial age hardening treatment is a remarkably low value of less than 900 MPa.

From the above results, the component composition of the copper alloy sheet of the present invention for making the tensile strength of the copper alloy sheet after artificial age hardening treatment 900 MPa or more, the conductivity 20% IACS or more, and excellent bending workability, and the average particle diameter defined in the Ni ₂ Si precipitates in the tissue, the critical significance of the mean spacing provisions of Ni ₂ Si precipitate is supported.

  As described above, according to the present invention, a Corson-based copper alloy plate having a high strength having a tensile strength of 900 MPa or more, an electrical conductivity of 20% IACS or more, and good bending workability. Can be provided. As a result, it is a connector, terminal, switch, relay, lead frame, etc. of electronic equipment that has been reduced in size and weight, and it is an application that requires a tensile strength of 900 MPa or more and a conductivity of 20% IACS or more, Moreover, it can be applied to applications that require strict bending workability such as 90 ° bending after notching.

It shows the structure of the copper alloy plate of the present invention, and is a transmission electron microscope structure photograph of 1 million times instead of the drawing. The structure of a comparative example copper alloy board is shown, and it is a transmission electron microscope structure photograph of 1 million times instead of drawing. It is the structure | tissue photograph replaced with drawing which looked at the copper alloy board structure | tissue with the transmission electron microscope of 150,000 times. It is the structure | tissue photograph replaced with drawing which looked at the copper alloy board structure | tissue with the transmission electron microscope of 150,000 times.

Claims (4)

A copper alloy plate containing Ni; 4.0 to 5.0% by mass, Si containing a mass ratio of Ni and Si, Ni / Si being in the range of 4 to 5, and the balance being substantially made of copper and inevitable impurities The average particle size of Ni ₂ Si precipitates present in the copper alloy sheet structure when the copper alloy sheet after the artificial age hardening treatment was observed with a transmission electron microscope of 1 million times. 3 to 10 nm, the average interval of Ni ₂ Si precipitates is 25 nm or less, the tensile strength of this copper alloy plate is 900 MPa or more, and the conductivity is 20% IACS or more. High strength copper alloy sheet.   The copper alloy plate is further mass%, Sn: 0.1-4.0%, Zn: 0.1-1.0%, Ag: 0.001-1.0%, Mn: 0.01-0.1%, Zr: 0.001-0.1%, Co: 0.01- The high-strength copper alloy sheet according to claim 1, containing 0.3%, one kind or two or more kinds. Ni; 4.0 to 5.0% by mass, and Si is included so that the mass ratio of Ni and Si is in the range of 4 to 5, with the balance being substantially composed of copper and inevitable impurities, and the balance being A copper alloy rolled plate substantially composed of copper and inevitable impurities is water-cooled after solution treatment, and further subjected to artificial age hardening treatment after cold rolling, or this cold rolling and artificial age hardening treatment are performed. step is performed repeatedly two or more times to obtain a copper alloy sheet, of observing a copper alloy sheet tissues million times of transmission electron microscope, the Ni ₂ Si precipitates present in the copper alloy plate in tissue The average particle size is 3 to 10 nm, the average interval of Ni ₂ Si precipitates is 25 nm or less, the tensile strength of the copper alloy plate is 900 MPa or more, and the conductivity is 20% IACS or more. A method for producing a high-strength copper alloy sheet. The rolled copper alloy sheet is further mass%, Sn: 0.1-4.0%, Zn: 0.1-1.0%, Ag: 0.001-1.0%, Mn: 0.01-0.1%, Zr: 0.001-0.1%, Co: 0.01 The manufacturing method of the high intensity | strength copper alloy of Claim 3 containing 1 type or 2 types or more of -0.3%.

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