JP6927844B2 - Copper alloy plate material and its manufacturing method - Google Patents

Description

The present invention relates to a copper alloy plate material and a method for producing the same, and more particularly to a Cu—Zn—Sn-based copper alloy plate material used for electrical and electronic parts such as connectors, lead frames, relays, and switches, and a method for producing the same.

Materials used for electrical and electronic components such as connectors, lead frames, relays, and switches are required to have good conductivity in order to suppress the generation of Joule heat due to energization, and when assembling and operating electrical and electronic equipment. High strength is required to withstand the stress sometimes applied. Further, since electrical and electronic parts such as connectors are generally formed by bending, excellent bending workability is also required. Furthermore, in order to ensure contact reliability between electrical and electronic components such as connectors, it is also required to have excellent durability against the phenomenon (stress relaxation) in which the contact pressure decreases with time, that is, excellent stress relaxation resistance characteristics. There is.

In recent years, electrical and electronic components such as connectors have tended to be highly integrated, downsized, and lightened, and along with this, there is an increasing demand for thinning of copper and copper alloy plates as raw materials. Therefore, the strength level required for the material is becoming more stringent. Further, in order to cope with the miniaturization and complicated shape of electrical and electronic parts such as connectors, it is required to improve the shape and dimensional accuracy of the bent product. In recent years, there has been a tendency to reduce the environmental load and save resources and energy. Along with this, copper and copper alloy plates, which are the raw materials, have reduced raw material costs and manufacturing costs, and have recyclability of products. The demand for is increasing.

However, since there are trade-offs between the strength and conductivity of the plate material, between the strength and bendability, and between the bendability and stress relief characteristics, conventional electricity such as such connectors has been used. As the plate material for electronic parts, a plate material having good conductivity, strength, bending workability or stress relaxation resistance and relatively low cost is appropriately selected and used depending on the application.

Further, conventionally, brass, phosphorus bronze and the like have been used as general-purpose materials for electrical and electronic parts such as connectors. Phosphor bronze has a relatively excellent balance of strength, corrosion resistance, stress corrosion cracking resistance and stress relaxation resistance, but for example, in the case of phosphor bronze type 2 (C5191), hot working cannot be performed. It contains about 6% of expensive Sn, which is disadvantageous in terms of cost.

On the other hand, brass (Cu—Zn-based copper alloy) is widely used as a material having low raw materials and manufacturing costs and excellent recyclability of products. However, the strength of brass is lower than that of phosphor bronze, and the quality of brass having the highest strength is EH (H06). For example, in a strip product of brass type 1 (C2600-SH), the tensile strength is generally 550 MPa. This tensile strength corresponds to the tensile strength of the two types of phosphor bronze, H (H04). Further, the brass strip product of type 1 (C2600-SH) is also inferior in stress corrosion cracking resistance.

Further, in order to improve the strength of brass, it is necessary to increase the finish rolling ratio (increase in quality), and accordingly, the bending workability in the direction perpendicular to the rolling direction (that is, the bending axis is rolled). Bending workability in a direction parallel to the direction) is significantly deteriorated. Therefore, even brass having a high strength level may not be able to be processed into electrical and electronic parts such as connectors. For example, if the finish rolling ratio of brass type 1 is increased and the tensile strength is higher than 570 MPa, it becomes difficult to press-mold into small parts.

In particular, in a simple alloy-based brass composed of Cu and Zn, it is not easy to improve bending workability while maintaining strength. Therefore, various elements have been added to brass to raise the strength level. For example, Cu—Zn-based copper alloys to which a third element such as Sn, Si, and Ni have been added have been proposed (see, for example, Patent Documents 1 to 3).

Japanese Unexamined Patent Publication No. 2001-164328 (paragraph number 0013) Japanese Unexamined Patent Publication No. 2002-88428 (paragraph number 0014) Japanese Unexamined Patent Publication No. 2009-62610 (paragraph number 0019)

However, even if Sn, Si, Ni, or the like is added to brass (Cu—Zn-based copper alloy), the bending workability may not be sufficiently improved.

Therefore, in view of such conventional problems, the present invention provides an inexpensive copper alloy plate material having excellent bending workability and stress corrosion cracking resistance while maintaining high strength, and a method for producing the same. The purpose is.

As a result of diligent research to solve the above problems, the present inventors have found 17 to 32% by mass of Zn, 0.1 to 4.5% by mass of Sn, and 0.01 to 2.0% by mass of Si. A copper alloy raw material containing 0.01 to 5.0% by mass of Ni, the balance of which is Cu and an unavoidable impurity is melted and cast, and hot rolling is performed in a temperature range of 900 ° C. to 400 ° C. After that, it is cooled to 400 ° C. to 300 ° C. at a cooling rate of 1 to 15 ° C./min, then cold rolling is performed, then recrystallization annealing is performed at 300 to 800 ° C., and then aging annealing is performed at 300 to 600 ° C. By doing so, it has been found that an inexpensive copper alloy plate material having excellent bending workability and excellent stress-corrosion-cracking resistance can be produced while maintaining high strength, and the present invention has been completed.

That is, the method for producing a copper alloy plate according to the present invention is 17 to 32% by mass of Zn, 0.1 to 4.5% by mass of Sn, 0.01 to 2.0% by mass of Si, and 0.01 to 5%. A copper alloy raw material containing 0.0% by mass of Ni, the balance of which is Cu and an unavoidable impurity is melted and cast, and after hot rolling in a temperature range of 900 ° C to 400 ° C, 400 ° C to Copper is cooled to 300 ° C. at a cooling rate of 1 to 15 ° C./min, followed by cold rolling, recrystallization annealing at 300 to 800 ° C., and then aging annealing at 300 to 600 ° C. It is characterized by producing an alloy plate material.

In this method for producing a copper alloy plate material, it is preferable to perform aging annealing, then finish cold rolling, and then low-temperature annealing at a temperature of 450 ° C. or lower. Alternatively, cold rolling may be performed after recrystallization annealing and before aging annealing. Further, the raw material of the copper alloy is a total of one or more elements selected from the group consisting of Fe, Co, Cr, Mg, Al, B, P, Zr, Ti, Mn, Au, Ag, Pb, Cd and Be. It may have a composition further contained in the range of 3% by mass or less.

Further, the copper alloy plate material according to the present invention contains 17 to 32% by mass of Zn, 0.1 to 4.5% by mass of Sn, 0.01 to 2.0% by mass of Si, and 0.01 to 5.0% by mass. A copper alloy plate containing% Ni and having a composition in which the balance is Cu and unavoidable impurities. It is characterized in that the time until cracks are observed in the copper alloy plate material while being held in the data is 10 times or more that of the copper type 1 (C2600-SH) plate material. In this copper alloy plate material, the number of coarse precipitates having a particle size of 1 μm or more per unit area of the surface ^{is preferably 15,000 / mm 2} or less.

Further, the copper alloy plate material according to the present invention contains 17 to 32% by mass of Zn, 0.1 to 4.5% by mass of Sn, 0.01 to 2.0% by mass of Si, and 0.01 to 5.0% by mass. A copper alloy plate material containing% Ni and having a composition in which the balance is Cu and an unavoidable impurity is characterized in that the ^{number of coarse precipitates having a particle size of 1 μm or more per unit area of the surface is 15,000 / mm 2 or less.} do.

In the above copper alloy plate material, the tensile strength is preferably 550 MPa or more, and the 0.2% proof stress is preferably 500 MPa or more. Further, the conductivity is preferably 10% IACS or more. Further, the copper alloy plate material contains a total of 3 or more elements selected from the group consisting of Fe, Co, Cr, Mg, Al, B, P, Zr, Ti, Mn, Au, Ag, Pb, Cd and Be. It may have a composition further contained in the range of mass% or less. Further, it is preferable that the average crystal grain size on the surface of the copper alloy plate material is 10 μm or less.

Further, the connector terminal according to the present invention is characterized in that the above-mentioned copper alloy plate material is used as a material.

According to the present invention, it is possible to produce an inexpensive copper alloy plate material having excellent bending workability and stress corrosion cracking resistance while maintaining high strength.

Embodiments of the method for producing a copper alloy plate material according to the present invention include 17 to 32% by mass of Zn, 0.1 to 4.5% by mass of Sn, 0.01 to 2.0% by mass of Si, and 0.01. A melting / casting step of melting and casting a raw material of a copper alloy containing ~ 5.0% by mass of Ni and having a composition in which the balance is Cu and an unavoidable impurity, and 900 ° C. to 400 ° C. after this melting / casting step. A hot rolling process in which hot rolling is performed in the above temperature range and then cooled to 400 ° C. to 300 ° C. at a cooling rate of 1 to 15 ° C./min, and a cold rolling process in which cold rolling is performed after this hot rolling process. After this cold rolling step, a recrystallizing ablation step of performing recrystallization annealing at 300 to 800 ° C., a aging annealing step of performing ablation at 300 to 600 ° C. after this recrystallizing ablation step, and, if necessary, After this aging annealing step, a finish cold rolling step of performing finish cold rolling and a low temperature quenching step of performing low temperature annealing at a temperature of 450 ° C. or lower are provided after this finish cold rolling step. Hereinafter, these steps will be described in detail. After hot rolling, surface milling may be performed as necessary, and after each heat treatment, pickling, polishing, and degreasing may be performed as necessary.

(Melting / casting process)
After melting the raw material of the copper alloy by the same method as the general brass melting method, slabs are manufactured by continuous casting or semi-continuous casting. The atmosphere at which the raw materials are dissolved is sufficient.

(Hot rolling process)
Usually, hot rolling of Cu-Zn-based copper alloy is performed in a high temperature range of 650 ° C or higher or 700 ° C or higher, and recrystallization during rolling and between rolling passes causes destruction of the cast structure and softening of the material. Will be done. However, rolling at a high temperature exceeding 900 ° C. is not preferable because cracks may occur in a portion where the melting point is lowered, such as a segregated portion of the alloy component. Therefore, when cooling to room temperature after hot rolling at 900 ° C. to 400 ° C., the average cooling rate from 400 ° C. to 300 ° C. is set to 1 to 15 ° C./min.

(Cold rolling process)
In this cold rolling step, the processing ratio is preferably 50% or more, more preferably 80% or more, and most preferably 90% or more. This cold rolling may be repeated with an intermediate annealing performed at 300 to 650 ° C. in between.

(Recrystallization annealing process)
In this recrystallization annealing step, annealing is performed at 300 to 800 ° C. Further, in this intermediate annealing step, it is preferable to perform heat treatment by setting the holding time and the ultimate temperature at 300 to 800 ° C. so that the average crystal grain size after annealing is 10 μm or less (preferably 9 μm or less). The grain size of the recrystallized grains by this annealing varies depending on the processing rate and chemical composition of cold rolling before annealing, but the relationship between the annealing heat pattern and the average crystal grain size was determined in advance by experiments for each alloy. Then, the holding time and the ultimate temperature can be set at 300 to 800 ° C. Specifically, in the chemical composition of the copper alloy plate material according to the present invention, it is held at 300 to 800 ° C. (preferably 450 to 800 ° C., more preferably 500 to 800 ° C., most preferably 575 to 800 ° C.) for several seconds to several hours. Appropriate conditions can be set for the heating conditions to be applied.

(Aging annealing process)
In this aging annealing step, annealing is performed at 300 to 600 ° C. (preferably 350 to 550 ° C.). The aging annealing temperature is preferably a temperature lower than the recrystallization annealing temperature. Cold rolling may be performed after recrystallization annealing and before aging annealing. In this case, finish cold rolling and low-temperature annealing may not be performed.

(Finishing cold rolling process)
Finish cold rolling is performed to improve the strength level. If the processing rate of the finish cold rolling is too low, the strength will be low, but if the processing rate of the finish cold rolling is too high, it will not be possible to realize crystal orientation with improved both strength and bending workability. Therefore, in this finish cold step, the processing rate is preferably 1 to 40%, more preferably 3 to 35%.

(Low temperature annealing process)
After finish cold rolling, in order to improve stress corrosion cracking resistance and bending workability by reducing residual stress of copper alloy plate material, and to improve stress relaxation resistance by reducing dislocations on pores and slip surfaces. Low temperature annealing may be performed. By this low temperature annealing, strength, stress corrosion cracking resistance, bending workability and stress relaxation resistance can be improved at the same time, and conductivity can be increased. If this heating temperature is too high, it will soften in a short time, and the characteristics will easily vary regardless of whether it is a batch type or a continuous type. Therefore, in this low-temperature annealing step, annealing is performed at a temperature of 450 ° C. or lower (preferably 300 to 450 ° C.).

The embodiment of the copper alloy plate material according to the present invention can be produced by the embodiment of the method for producing a copper alloy plate material described above.

Embodiments of the copper alloy plate material according to the present invention include 17 to 32% by mass of Zn, 0.1 to 4.5% by mass of Sn, 0.01 to 2.0% by mass of Si, and 0.01 to 5. In a copper alloy plate material containing 0% by mass of Ni and having a composition in which the balance is Cu and unavoidable impurities, a copper alloy plate material to which a bending stress corresponding to 80% of 0.2% withstand strength is applied is mixed with 3% by mass of aqueous ammonia. It is held at 25 ° C. in the placed desiccator, and the time until cracks are observed in the copper alloy plate material is 10 times or more that of the brass type 1 (C2600-SH) plate material.

An embodiment of the copper alloy plate material according to the present invention is a plate material made of a Cu—Zn—Sn—Si—Ni alloy in which Sn, Si and Ni are added to a Cu—Zn-based alloy containing Cu and Zn.

Zn has the effect of improving the strength and springiness of the copper alloy plate material. Since Zn is cheaper than Cu, it is preferable to add a large amount of Zn. However, when the Zn content exceeds 32% by mass, the formation of the β phase significantly reduces the cold workability of the copper alloy plate, the stress corrosion cracking resistance, and the plating property due to moisture and heating. And solderability also deteriorates. On the other hand, if the Zn content is less than 17% by mass, the strength and springiness such as 0.2% strength and tensile strength of the copper alloy plate material are insufficient, the Young's modulus becomes large, and when the copper alloy plate material is melted. The amount of hydrogen gas occluded is large, the alloy is likely to be alloyed, and the amount of inexpensive Zn is small, which is economically disadvantageous. Therefore, the Zn content is preferably 17 to 32% by mass, more preferably 18 to 31% by mass.

Sn has the effect of improving the strength, stress relaxation resistance and stress corrosion cracking resistance of the copper alloy plate material. It is preferable that the copper alloy plate contains Sn in order to reuse the material surface-treated with Sn such as Sn plating. However, when the Sn content exceeds 4.5% by mass, the conductivity of the copper alloy plate material drops sharply, and the grain boundary segregation becomes severe in the coexistence with Zn, and the hot workability is remarkably lowered. .. On the other hand, if the Sn content is less than 0.1% by mass, the effect of improving the mechanical properties of the copper alloy plate material is reduced, and it becomes difficult to use press scraps or the like subjected to Sn plating as a raw material. Therefore, when the copper alloy plate contains Sn, the Sn content is preferably 0.1 to 4.5% by mass, more preferably 0.2 to 2.5% by mass.

Even a small amount of Si has the effect of improving the stress corrosion cracking resistance of the copper alloy plate material. In order to obtain this effect sufficiently, the Si content is preferably 0.01% by mass or more. However, if the Si content exceeds 2.0% by mass, the conductivity is likely to decrease, and Si is an element that is easily oxidized and the castability is easily reduced. Therefore, the Si content should not be too high. good. Therefore, when the copper alloy plate contains Si, the Si content is preferably 0.01 to 2.0% by mass, more preferably 0.1 to 1.5% by mass. Further, Si forms a compound with Ni and is dispersed and precipitated to improve the conductivity, strength, spring limit value, and stress relaxation resistance of the copper alloy plate material.

Ni has the effect of strengthening the solid solution of the copper alloy plate and improving the stress relaxation resistance. In particular, the zinc equivalent of Ni is a negative value, and by suppressing the formation of β phase, the characteristics at the time of mass production. It has the effect of suppressing the variation of. In order to fully exert these effects, the Ni content is preferably 0.01% by mass or more. On the other hand, if the Ni content exceeds 5.0% by mass, the conductivity will be significantly reduced. Therefore, when the copper alloy plate contains Ni, the Ni content is preferably 0.01 to 5.0% by mass, more preferably 0.1 to 4.5% by mass.

Further, the copper alloy plate material contains a total of 3 or more elements selected from the group consisting of Fe, Co, Cr, Mg, Al, B, P, Zr, Ti, Mn, Au, Ag, Pb, Cd and Be. It may have a composition further contained in the range of mass% or less (preferably 1% by mass or less, more preferably 0.5% by mass or less).

The smaller the average crystal grain size of the copper alloy plate is, the more advantageous it is in improving the bending workability. Therefore, it is preferably 10 μm or less, more preferably 1 to 9 μm or less, and further preferably 2 to 8 μm. preferable.

The tensile strength of the copper alloy plate material is preferably 550 MPa or more, more preferably 600 MPa or more, and most preferably 640 MPa or more in order to reduce the size and thickness of electrical and electronic parts such as connectors. .. The 0.2% proof stress of the copper alloy plate material is preferably 500 MPa or more, more preferably 550 MPa or more, and most preferably 580 MPa or more.

The conductivity of the copper alloy plate material is preferably 10% IACS or more, preferably 15% IACS or more, in order to suppress the generation of jule heat due to energization due to the high integration of electrical and electronic parts such as connectors. Is even more preferable.

To evaluate the stress corrosion cracking resistance of copper alloy plates, a bending stress equivalent to 80% of 0.2% proof stress was applied to a test piece cut out from a copper alloy plate, and this test piece was filled with 3% by mass of ammonia water. When the test piece kept in the alloy at 25 ° C. and taken out every hour was observed to crack at a magnification of 100 times with an optical microscope, the time until the crack was observed was 50 hours or more. Is preferable, and 60 hours or more is more preferable. Further, this time is preferably 10 times or more, more preferably 12 times or more, as compared with a commercially available brass type 1 (C2600-SH) plate material.

Further, as an evaluation of the bending workability of the copper alloy plate material, a bending processing test piece cut out from the copper alloy plate material so that the longitudinal direction is TD (direction perpendicular to the rolling direction and the plate thickness direction) is used. When the 90 ° W bending test is performed with the LD (rolling direction) as the bending axis, the ratio R / t of the minimum bending radius R and the plate thickness t in the 90 ° W bending test is 1.0 or less. It is preferably 0.7 or less, more preferably 0.6 or less, and most preferably 0.6 or less.

Further, the number of coarse precipitates (particle size of 1 μm or more) per unit area of the surface of the copper alloy plate material ^{is preferably 15,000 pieces / mm 2} or less, and more preferably 12,000 pieces / mm ² or less. By suppressing the formation of coarse precipitates of Ni and Si and finely depositing Ni and Si in this way, the bending workability is excellent and the stress corrosion cracking resistance is excellent while maintaining high strength. A copper alloy plate material can be manufactured.

Hereinafter, examples of the copper alloy plate material and the method for producing the same according to the present invention will be described in detail.

[Examples 1 to 16, Comparative Examples 1 to 8]
A copper alloy containing 19.7% by mass Zn, 0.77% by mass Sn, 1.05% by mass Si, and 3.85% by mass Ni, with the balance being Cu (Example 1), 20.9. A copper alloy containing mass% Zn, 0.79 mass% Sn, 0.95 mass% Si, and 2.81 mass% Ni, with the balance being Cu (Example 2), 20.5 mass%. Copper alloy containing Zn, 0.71% by mass Sn, 0.98% by mass Si, 1.24% by mass Ni, and the balance being Cu (Example 3), 22.1% by mass Zn and 0 A copper alloy containing .79% by mass of Sn, 0.47% by mass of Si and 2.63% by mass of Ni, and the balance being Cu (Example 4), 19.9% by mass of Zn and 0.76% by mass. % Sn, 0.46% by mass Si and 1.67% by mass Ni, and the balance is Cu (Example 5) Copper alloy (Example 5), 20.2% by mass Zn and 0.77% by mass Sn A copper alloy containing 0.46% by mass of Si and 0.96% by mass of Ni, with the balance being Cu (Example 6), 19.8% by mass of Zn, 0.75% by mass of Sn, and 0. A copper alloy containing 49% by mass Si and 0.45% by mass Ni and the balance being Cu (Example 7), 19.8% by mass Zn, 0.25% by mass Sn and 1.01% by mass. (Example 8), a copper alloy containing 3.82% by mass of Ni and the balance of Cu, 21.1% by mass of Zn, 2.08% by mass of Sn, and 0.50% by mass of Si. Copper alloy containing 1.89% by mass of Ni and the balance being Cu (Example 9), 30.1% by mass Zn, 0.75% by mass Sn, 0.50% by mass Si and 1.78. A copper alloy containing mass% Ni and the balance being Cu (Example 10), 20.0 mass% Zn, 0.77 mass% Sn, 1.00 mass% Si, and 3.75 mass%. A copper alloy containing Ni and the balance being Cu (Example 11), containing 20.1% by mass Zn, 0.72% by mass Sn, 1.00% by mass Si, and 3.91% by mass Ni. , Copper alloy with Cu remaining (Example 12), 22.0% by mass Zn, 0.77% by mass Sn, 0.49% by mass Si, 2.00% by mass Ni and 0.15% by mass. % Fe, 0.08% by mass Co and 0.07% by mass Cr, and the balance is Cu (Example 13), 23.2% by mass Zn and 0.78% by mass Sn , 0.50% by mass Si, 2.01% by mass Ni, 0.08% by mass Mg, 0.08% by mass Al, 0.10% by mass Zr and 0.10% Ti, and the balance Is a copper alloy made of Cu (Example 1) 4) 22.5% by mass Zn, 0.80% by mass Sn, 0.49% by mass Si, 1.90% by mass Ni, 0.05% by mass B and 0.05% by mass P And 0.08% by mass of Mn and 0.10% by mass of Be, and the balance is Cu (Example 15), 21.5% by mass of Zn, 0.78% by mass of Sn, and 0. Contains 50% by mass Si, 1.85% by mass Ni, 0.05% by mass Au, 0.08% by mass Ag, 0.08% by mass Pb and 0.07% by mass Cd, with the balance remaining Copper alloy made of Cu (Example 16), a copper alloy containing 24.5% by mass of Zn and 0.77% by mass of Sn, and the balance being made of Cu (Comparative Examples 1 and 2), 24.5% by mass. A copper alloy containing Zn, 0.77% by mass Sn, 0.50% by mass Si, and 1.99% by mass Ni, with the balance being Cu (Comparative Examples 3 to 4), 24.5% by mass Zn. A copper alloy containing 0.77% by mass of Sn, 1.89% by mass of Ni and 0.02% by mass of P, and the balance being Cu (Comparative Example 5), 24.0% by mass of Zn and 0. A copper alloy containing 77% by mass of Sn and 1.97% by mass of Ni, with the balance being Cu (Comparative Example 6), 19.8% by mass of Zn, 0.75% by mass of Sn, and 0.49% by mass. 40 mm x 40 mm x 20 mm, respectively, from the ingots obtained by melting and casting copper alloys (Comparative Examples 7 to 8) containing Si and 0.45% by mass of Ni and the balance being Cu. The slab was cut out.

After heating each slab at 800 ° C. for 30 minutes, it was hot-rolled in a temperature range of 800 ° C. to 400 ° C. to a thickness of 10 mm (processing rate 50%), and then cooled from 400 ° C. to room temperature. Of these cooling, the cooling between 400 ° C. and 300 ° C. was performed in Examples 1 to 12 at an average cooling rate of 5 ° C./min (Examples 1, 3, 4, 6, 7, 9 to 13, 15, respectively). 16, Comparative Examples 5 to 6), 10 ° C./min (Example 2), 2 ° C./min (Examples 5, 8, 14), 20 ° C./min (Comparative Examples 4, 8), and Comparative Example 1. In ~ 3 and 7, this was done by quenching with water.

Next, the thickness is 0.26 mm (Examples 1, 2, 9, Comparative Example 3), 0.28 mm (Examples 3 to 5, 8, 10, 13 to 16, Comparative Example 4), 0.4 mm ( Cold rolling was performed to Examples 6 to 7, Comparative Examples 7 to 8), 0.38 mm (Example 11, Comparative Examples 1, 2, 5, 6) and 0.30 mm (Example 12). In Comparative Examples 1, 5 and 6, cold rolling was performed twice with intermediate annealing held at 550 ° C, 625 ° C and 550 ° C for 1 hour, respectively.

Next, 800 ° C. for 10 minutes (Examples 1, 11, 12), 750 ° C. for 10 minutes (Examples 2 to 5, 10, 13 to 16, Comparative Examples 3 to 4), and 600 ° C. for 10 minutes (Examples 1 and 11 and 12). Examples 6-7, Comparative Examples 7-8), 700 ° C. for 30 minutes (Examples 8 and 9), 550 ° C. for 30 minutes (Comparative Examples 1 and 6), 525 ° C. for 30 minutes (Comparative Example 2), Intermediate annealing (recrystallization annealing) was performed by holding at 600 ° C. for 30 minutes (Comparative Example 5). Then, in Examples 6 to 7 and Comparative Examples 7 to 8, cold rolling was performed to a thickness of 0.25 mm.

Next, in Examples 1 to 16 and Comparative Examples 3 to 4 and 7 to 8, respectively, at 425 ° C. for 3 hours (Examples 1 to 5, 10 to 11, 13 to 16, Comparative Examples 3 to 4), 450 ° C. 30 minutes (Examples 6 to 7, Comparative Examples 7 to 8), 500 ° C. for 3 hours (Example 8), 350 ° C. for 3 hours (Example 9), 550 ° C. for 3 hours (Example 12) The aging annealing was performed.

Next, in Examples 1 to 5, 8 to 16 and Comparative Examples 1 to 6, the processing rates were 5% (Examples 1, 2, 9, Comparative Example 3) and 11% (Examples 3 to 5, 8, respectively. After performing finish cold rolling at 10, 13 to 16, Comparative Example 4), 33% (Example 11, Comparative Examples 1 to 2, 5 to 6) and 16% (Example 12), each at 350 ° C. Low temperature annealing was carried out for 30 minutes (Examples 1 to 5, 8 to 16, Comparative Examples 3 to 5) and holding at 300 ° C. for 30 minutes (Comparative Examples 1 to 2 and 6).

Samples were taken from the copper alloy plates of Examples 1 to 16 and Comparative Examples 1 to 8 thus obtained, and the average crystal grain size, conductivity, tensile strength, stress corrosion cracking resistance, and stress corrosion cracking resistance of the crystal grain structure were obtained. The bending workability was investigated as follows.

The average crystal grain size of the crystal grain structure was measured by polishing the plate surface (rolled surface) of the copper alloy plate material and then etching the surface, observing the surface with an optical microscope, and measuring by the cutting method of JIS H0501. As a result, the average crystal grain size was 5 μm (Examples 1, 3 to 5, 7, 12, Comparative Examples 1 to 2, 7 to 8) and 4 μm (Examples 2, 10, 11, 13 to 16, comparative). Examples 3 to 6), 6 μm (Example 6), and 3 μm (Examples 8 and 9).

The conductivity of the copper alloy plate material was measured according to the conductivity measuring method of JIS H0505. As a result, the conductivity was 21.7% IACS (Example 1), 20.6% IACS (Example 2), 16.4% IACS (Example 3), and 23.9% IACS (Example 4). ), 23.6% IACS (Example 5), 20.6% IACS (Example 6), 19.5% IACS (Example 7), 27.9% IACS (Example 8), 18.5%. IACS (Example 9), 19.2% IACS (Example 10), 22.0% IACS (Example 11), 21.7% IACS (Example 12), 23.4% IACS (Example 13) , 23.5% IACS (Example 14), 24.0% IACS (Example 15), 22.1% IACS (Example 16), 25.3% IACS (Comparative Example 1), 24.8% IACS (Comparative Example 2), 19.5% IACS (Comparative Example 3), 21.6% IACS (Comparative Example 4), 18.2% IACS (Comparative Example 5), 16.2% IACS (Comparative Example 6), It was 19.5% IACS (Comparative Example 7) and 19.5% IACS (Comparative Example 8).

As the tensile strength as a mechanical property of the copper alloy plate material, three test pieces (JIS Z2201 No. 5 test piece) for the LD (rolling direction) tensile test of the copper alloy plate material were collected and tested for each. A tensile test based on JIS Z2241 was performed on the piece, and 0.2% proof stress and tensile strength of LD were determined by the average value. As a result, the 0.2% proof stress and tensile strength of the LD were 589 MPa and 677 MPa (Example 1), 554 MPa and 637 MPa (Example 2), 587 MPa and 652 MPa (Example 3), and 587 MPa and 676 MPa (Example 1). 4), 601 MPa and 664 MPa (Example 5), 633 MPa and 682 MPa (Example 6), 630 MPa and 680 MPa (Example 7), 590 MPa and 655 MPa (Example 8), 590 MPa and 685 MPa (Example 9), 585 MPa. 644 MPa (Example 10), 660 MPa and 735 MPa (Example 11), 583 MPa and 677 MPa (Example 12), 601 MPa and 651 MPa (Example 13), 598 MPa and 655 MPa (Example 14), 600 MPa and 653 MPa (Example 15). ), 595 MPa and 658 MPa (Example 16), 593 MPa and 659 MPa (Comparative Example 1), 589 MPa and 660 MPa (Comparative Example 2), 583 MPa and 650 MPa (Comparative Example 3), 583 MPa and 650 MPa (Comparative Example 4), 596 MPa and 652 MPa. (Comparative Example 5), 584 MPa and 642 MPa (Comparative Example 6), 625 MPa and 675 MPa (Comparative Example 7), 623 MPa and 678 MPa (Comparative Example 8).

The stress corrosion cracking resistance of the copper alloy plate is arched so that the surface stress at the center of the longitudinal direction of the test piece with a width of 10 mm collected from the copper alloy plate is 0.2% and the surface stress is 80% of the yield strength. A test piece with a width of 10 mm, which was held at 25 ° C. in a desiccator containing 3% by mass of aqueous ammonia in a bent state and taken out every hour, was observed to crack at a magnification of 100 times with an optical microscope. As a result, 75 hours (Example 1), 76 hours (Example 2), 89 hours (Example 3), 64 hours (Example 4), 67 hours (Example 5), and 80 hours (Example 6), respectively. ), 75 hours (Example 7), 75 hours (Example 8), 128 hours (Example 9), 87 hours (Example 10), 65 hours (Example 11), 66 hours (Example 12), 75 hours (Example 13), 74 hours (Example 14), 72 hours (Example 15), 75 hours (Example 16), 24 hours (Comparative Example 1), 25 hours (Comparative Example 2), 39 hours Cracking was observed after 37 hours (Comparative Example 4), 30 hours (Comparative Example 5), 25 hours (Comparative Example 6), 30 hours (Comparative Example 7), and 24 hours (Comparative Example 8). Compared with the commercially available brass type 1 (C2600-SH) plate material, the time until cracking is observed is 15 times (Example 1), 15 times (Example 2), and 18 times (Example 3), respectively. ), 13 times (Example 4), 13 times (Example 5), 16 times (Example 6), 15 times (Example 7), 15 times (Example 8), 26 times (Example 9), 17 times (Example 10), 13 times (Example 11), 13 times (Example 12), 15 times (Example 13), 15 times (Example 14), 14 times (Example 15), 15 times (Example 16), 5 times (Comparative Example 1), 5 times (Comparative Example 2), 8 times (Comparative Example 3), 7 times (Comparative Example 4), 6 times (Comparative Example 5), 5 times (Comparison) Examples 6), 6 times (Comparative Example 7), and 5 times (Comparative Example 8).

In order to evaluate the bending workability of the copper alloy plate material, a bending test piece (width 10 mm) is cut out from the copper alloy plate material so that the longitudinal direction is TD (direction perpendicular to the rolling direction and the plate thickness direction). A 90 ° W bending test conforming to JIS H3110 was performed with the LD (rolling direction) as the bending axis (Bad Way bending (BW bending)). For the test piece after this test, the surface and cross section of the bent portion were observed with an optical microscope at a magnification of 100 times to obtain the minimum bending radius R at which cracks did not occur, and this minimum bending radius R was determined by the copper alloy plate. Each R / t value was obtained by dividing by the thickness t. As a result, R / t was 0.4 (Examples 1, 2, 6 to 8), 0.6 (Examples 3 to 5, 9 to 16), and 0.8 (Comparative Examples 1 to 8), respectively. there were.

In addition, samples were taken from the copper alloy plates of Examples 1 to 16 and Comparative Examples 3 to 4 and 7 to 8, and coarse precipitates on the surface (particle size (diameter of the smallest circle surrounding the precipitate) of 1 μm or more). The number (per unit area) of was examined. The number of coarse precipitates on the surface of the copper alloy plate was electrolyzed by energizing a sample collected from the copper alloy plate as an anode and a stainless plate as a cathode at a voltage of 15 V for 30 seconds in 20% by mass of phosphoric acid. After that, using a scanning electron microscope, the secondary electron image of the precipitate on the surface of the sample was observed at a magnification of 3000 times, and the coarse precipitate was counted. As a result, the number of coarse deposits on the surface of the copper alloy plate was 7700 / mm ² (Example 1), 5000 / mm ² (Example 2), 2100 / mm ² (Example 3), and 7800, respectively. Pieces / mm ² (Example 4), 8800 pieces / mm ² (Example 5), 600 pieces / mm ² (Example 6), 600 pieces / mm ² (Example 7), 7500 pieces / mm ² (Implementation) Example 8), 7000 pieces / mm ² (Example 9), 7600 pieces / mm ² (Example 10), 7700 pieces / mm ² (Example 11), 11000 pieces / mm ² (Example 12), 7200 pieces / Mm ² (Example 13), 6900 pieces / mm ² (Example 14), 8000 pieces / mm ² (Example 15), 7800 pieces / mm ² (Example 16), 20600 pieces / mm ² (Comparative example) 3) 21000 pieces / mm ² (Comparative Example 4), 16000 pieces / mm ² (Comparative Example 7) and 17800 pieces / mm ² (Comparative Example 8).

The manufacturing conditions and characteristics of these Examples and Comparative Examples are shown in Tables 1 to 3.

Claims (13)

Contains 17-32% by mass Zn, 0.1-4.5% by mass Sn, 0.01-2.0% by mass Si and 0.01-5.0% by mass of Ni, with the balance being Cu and A raw material of a copper alloy having a composition that is an unavoidable impurity is melted and cast, and after hot rolling in a temperature range of 900 ° C to 400 ° C, it is cooled to 400 ° C to 300 ° C at a cooling rate of 1 to 15 ° C / min. Then, after cold rolling, recrystallization annealing is performed at 300 to 800 ° C., and then aging annealing is performed at 300 to 600 ° C. to produce a copper alloy plate material. Method of manufacturing plate material. The method for producing a copper alloy plate material according to claim 1, wherein after the aging annealing, finish cold rolling is performed, and then low-temperature annealing is performed at a temperature of 450 ° C. or lower. The method for producing a copper alloy plate material according to claim 1, wherein cold rolling is performed after the recrystallization annealing and before the aging annealing. A total of 3 elements selected from the group consisting of Fe, Co, Cr, Mg, Al, B, P, Zr, Ti, Mn, Au, Ag, Pb, Cd and Be as the raw material of the copper alloy. The method for producing a copper alloy plate material according to any one of claims 1 to 3, further comprising a composition in the range of mass% or less. Contains 17-32% by mass Zn, 0.1-4.5% by mass Sn, 0.01-2.0% by mass Si and 0.01-5.0% by mass of Ni, with the balance being Cu and In a copper alloy plate having a composition that is an unavoidable impurity, a copper alloy plate to which a bending stress corresponding to 80% of 0.2% withstand strength is applied is held at 25 ° C. in a desiccator containing 3% by mass of ammonia water. The copper alloy plate material is characterized in that the time until cracks are observed in the copper alloy plate material is 10 times or more that of the brass type 1 (C2600-SH) plate material. The copper alloy plate material according to claim 5, wherein the number of coarse precipitates having a particle size of 1 μm or more per unit area of the surface of the copper alloy plate material is 15,000 pieces / mm ^{2 or less.} It contains 17-32% by mass Zn, 0.1-4.5% by mass Sn, 0.01-2.0% by mass Si and 0.01-5.0% by mass Ni, and the balance is Cu and A copper alloy plate having a composition that is an unavoidable impurity, wherein the number of coarse precipitates having a particle size of 1 μm or more per unit area of the surface is 15,000 / mm ² or less. The copper alloy plate material according to any one of claims 5 to 7, wherein the tensile strength of the copper alloy plate material is 550 MPa or more. The copper alloy plate material according to any 6 of claims 5 to 8, wherein the 0.2% proof stress of the copper alloy plate material is 500 MPa or more. The copper alloy plate material according to any one of claims 5 to 9, wherein the copper alloy plate material has a conductivity of 10% IACS or more. The copper alloy plate material contains a total of 3 masses of one or more elements selected from the group consisting of Fe, Co, Cr, Mg, Al, B, P, Zr, Ti, Mn, Au, Ag, Pb, Cd and Be. The copper alloy plate material according to any one of claims 5 to 10, further comprising a composition in the range of% or less. The copper alloy plate material according to any one of claims 5 to 11, wherein the average crystal grain size of the surface of the copper alloy plate material is 10 μm or less. A connector terminal using the copper alloy plate material according to any one of claims 5 to 12 as a material.