KR101573163B1 - Cu-Zn-Sn-Ni-P-BASED ALLOY - Google Patents

Abstract

It is possible to obtain a copper alloy which contains 3 mass% or more of Zn which is lower in raw material value than Cu or Ni and which permits inclusion of Sn incorporated in copper scrap and is low in cost and excellent in strength, bending property and stress relaxation property, In order to provide a Cu-Zn-Sn-Ni-P alloy with a small amount, 0.2 to 0.8% of Sn, 3 to 18% of Zn, 0.3 to 1.2% of Ni and 0.01 to 0.12% , The remainder being made of Cu and inevitable impurities and having a crystal grain size a in the rolling parallel direction and a crystal grain size b in the direction perpendicular to the rolling direction of 0.9 to 1.4 and a ratio Ni / -P-based compound particles having a number density of the following range was produced.
(1) Ni-P-based compound particles A having a particle size of 2.0 m or larger are 10 particles / mm 2 or less
(2) Ni-P based compound particles B having a diameter of 100 nm or more and 500 nm or less of 50 / mm 2 or more and 500 / mm 2 or less

Description

Cu-Zn-Sn-Ni-P-based alloy {Cu-Zn-Sn-Ni-P-BASED ALLOY}

The present invention relates to a Cu-Zn-Sn-Ni-P alloy suitable for conductive spring materials such as connectors, terminals, relays, switches and the like.

Conventionally, brass or phosphor bronze, which is a solid solution strengthening alloy, has been used as a material for terminals and connectors. [0004] However, with the weight reduction and miniaturization of electronic devices, terminals and connectors have become thinner and smaller, and materials used therefor are required to have high strength and high bendability. Further, in a connector used in a high-temperature environment such as an automobile engine room or the like, a material having a good stress relaxation resistance is required because a connector contact pressure is lowered due to a stress relaxation phenomenon.

However, since brass or phosphor bronze has insufficient strength and stress relaxation characteristics, precipitation strengthening alloys are widely used in recent years. Particularly, among the precipitation-strengthening alloys, Cu-Ni-Si alloys are called Korson alloys and have high strength, high bending property and good stress relaxation characteristics by precipitation of Ni ₂ Si fine compounds, And is used for a vehicle-use connector (Patent Documents 1 to 8).

Japanese Laid-Open Patent Publication No. 2009-185341 Japanese Laid-Open Patent Publication No. 2009-62610 Japanese Patent Application Laid-Open No. 11-293367 Japanese Patent Application Laid-Open No. 2003-306732 Japanese Patent Application Laid-Open No. 2005-163127 Japanese Unexamined Patent Publication No. 5-33087 Japanese Patent Application Laid-Open No. 2007-84923 Japanese Patent Application Laid-Open No. 2007-107087

However, since the precipitation alloy is strengthened by precipitation by solidification of the solute element and aging treatment, the solution treatment at a high temperature and the aging treatment for a long time are required as compared with the solid solution alloy, so that an increase in manufacturing cost can not be avoided. In addition, due to recent rise in copper prices and nickel prices, it is desired to develop low-cost copper alloys capable of replacing them with inexpensive raw materials. In addition, although the terminal and connector are manufactured by punching and bending by press working from a copper alloy tank, the degree of freedom is required in the direction of material layout at the time of press working with the miniaturization and high functioning of electronic parts. As a result, This small thing is required.

Disclosure of the Invention The present invention has been made in order to solve the above problems, and it is an object of the present invention to provide a copper scrap containing 3 mass% or more of Zn which is low in raw material value compared to Cu or Ni, Zn-Sn-Ni-P based alloy which is excellent in strength, bending property and stress relaxation property and is small in anisotropy.

In order to achieve the above object, the inventor of the present invention conducted intensive research and found that the crystal grain size a in the rolling parallel direction of the Cu-Zn-Sn-Ni-P alloy and the crystal grain size b in the direction perpendicular to the rolling direction The anisotropy was successfully reduced without adversely affecting the strength, bending property and stress relaxation property by suitably controlling the number-average particle size ratio a / b and the number density of the Ni-P system compound particles in the section in the rolling parallel direction .

That is, the Cu-Zn-Sn-Ni-P alloy according to the present invention contains 0.2 to 0.8% of Sn, 3 to 18% of Zn, 0.3 to 1.2% of Ni, 0.01 to 0.12% And the balance of Cu and inevitable impurities, the crystal grain size a in the rolling parallel direction a and the crystal grain size b in the rolling right angle direction are 0.9 to 1.4, and the crystal grain size b in the rolling parallel direction The number density of the Ni-P based compound particles is in the following range.

(1) Ni-P-based compound particles A having a particle size of 2.0 m or larger are 10 particles / mm 2 or less

(2) Ni-P based compound particles B having a diameter of 100 nm or more and 500 nm or less of 50 / mm 2 or more and 500 / mm 2 or less

The tensile strength of both GW and BW is 500 MPa or more, the difference in tensile strength between GW and BW is 50 MPa or less, the minimum bending radius MBR / t of GW and BW is all 1 or less and the difference in deformation constant between GW and BW is 10 Or less.

And further contains at least one member selected from the group consisting of Mg, Mn, Ti, Cr and Zr in a total amount of 0.02 to 0.25 mass%.

According to the present invention, it is possible to contain 3 mass% or more of Zn, which may be mixed with copper scrap, and to contain Sn incorporated in copper scrap, , A Cu-Zn-Sn-Ni-P alloy having excellent bending property and stress relaxation resistance and having small anisotropy can be obtained.

Hereinafter, a Cu-Zn-Sn-Ni-P alloy according to an embodiment of the present invention will be described. In the present invention, "%" means% by mass unless otherwise specified.

(Furtherance)

[Sn and Zn]

The concentration of Sn in the alloy is set to 0.2 to 0.8%, and the concentration of Zn is set to 3 to 18%. Sn and Zn improve the strength and heat resistance of the alloy, further improve the stress relaxation resistance of Sn, and improve the heat resistance of the solder joint of Zn. Incorporation of Zn in an amount of 3 mass% or more makes it possible to improve the tensile strength to 500 MPa or more, and also to reduce the manufacturing cost by using copper scrap containing Zn in the production of alloys. As described later, unless the recrystallization temperature is set to a low temperature (480 占 폚 or less) even when Zn is contained in an amount of 3 mass% or more, remarkable coarsening of the crystal grain size occurs and the strength is lowered and the tensile strength of 500 MPa or more is stably I can not get it.

If the content of Sn and Zn is less than the above range, the above-described effect can not be obtained. If the content exceeds the above range, the conductivity is lowered. If the content of Sn exceeds the above range, the hot workability is deteriorated. If the content of Zn exceeds the above range, the bending workability is lowered.

[Ni and P]

The concentration of Ni in the alloy is set to 0.3 to 1.2%, and the concentration of P is set to 0.01 to 0.12%. When both Ni and P are contained, fine precipitates of Ni ₃ P precipitate in the alloy even during a short-time heat treatment for recrystallization, so that the strength and stress relaxation resistance are improved.

If the content of Ni and P is less than the above range, precipitation of Ni ₃ P is not sufficient and desired strength and stress relaxation improving effect can not be obtained. If the content of Ni and P exceeds the above range, the bending workability and hot workability deteriorate in addition to the remarkable decrease in conductivity.

[Other addition elements]

The alloy may further contain at least one selected from the group of Mg, Mn, Ti, Cr and Zr in a total amount of 0.02 to 0.25 mass% for the purpose of improving the strength. In addition, Mg and Mn improve the stress relaxation property, and Cr and Mn improve the hot workability.

However, when these elements exceed the above range, they are oxidized during atmospheric dissolution at the time of ingot casting, so that unnecessary increase of the cost of the raw material, Thereby deteriorating the quality of the ingot.

[Crystal grain size]

The crystal grain size a / b in the direction parallel to the rolling direction and the crystal grain size b in the direction perpendicular to the rolling direction is 0.9 to 1.4. When a / b exceeds the above range, the difference in crystal grain size between the rolling parallel direction and the direction perpendicular to the rolling direction becomes large, and the bending workability in the BW direction is remarkably deteriorated. The reason for this is not clear, but it is considered that the difference in the workability when the fibrous structure oriented in one direction is bent in the fiber direction and in the direction perpendicular to the fiber direction is considered to be the difference. In other words, since the size of the crystal grains across the bending axis is larger in the BW direction than in the GW direction, it is conceivable that cracks are generated in a form propagating through the grain boundaries because the deformation during plastic deformation can not be absorbed by the slip deformation of the respective grains .

Further, the crystal grain size a is measured in accordance with the cutting method of JIS-H0501 for the rolling parallel cross section (cross section cut in a plane parallel to the rolling direction). The crystal grain size b is measured in accordance with the cutting method of JIS-H0501 with respect to the section perpendicular to the rolling direction (section cut on the plane parallel to the direction perpendicular to the rolling direction).

[Ni-P compound]

The number density of the Ni-P system compound particles in the section in the rolling parallel direction is controlled to fall within the following range.

(1) Ni-P-based compound particles A having a particle size of 2.0 m or larger are 10 particles / mm 2 or less

(2) Ni-P based compound particles B having a diameter of 100 nm or more and 500 nm or less of 50 / mm 2 or more and 500 / mm 2 or less

Here, the Ni-P based compound particles (hereinafter referred to as Ni-P based particles) are particles containing 50 at% or more of Ni and further containing 10 at% or more of P and the particle diameters of Ni- , And the diameter of the minimum circle surrounding the particles (hereinafter the same). When the number density of the particles A is more than 10 / mm 2, the bending properties of GW and BW deteriorate. The above-mentioned particles B are precipitates. When the number of particles is smaller than 50 / mm < 2 >, precipitation of Ni-P-based particles of less than 100 nm, which contributes to improvement of the stress relaxation resistance, becomes insufficient and desired stress relaxation characteristics can not be obtained. On the other hand, when the number of particles is 500 pieces / mm < 2 > or more, the Ni-P type particles grow and the particles less than 100 nm described above decrease, so that desired stress relaxation characteristics can not be obtained.

The reason why the particles A and B are Ni-P-based particles is that EDS (energy dispersive X-ray analysis) of particles having a typical shape (diameter) in a predetermined field of view of an FE- To confirm this. For the particles A and B, the parallel cross section of the sample is observed by FE-SEM, and the number of particles in the above-mentioned particle size range is measured by particle analysis software attached to the FE-SEM to obtain the number density.

The Cu-Zn-Sn-Ni-P alloy of the present invention can be produced by subjecting the ingot to hot rolling and machining, first cold rolling and recrystallization annealing, and finally cold rolling. Deformation removal annealing is performed after the final cold rolling.

Set the ingot injection temperature to 1250 캜 or lower. If the ingot temperature of the ingot exceeds 1250 deg. C, the cast structure becomes coarse, even dynamic recrystallization at the end of hot rolling can not be sufficiently solved, and coarse structure remains. As a result, even in the product, crystal grains elongated in the longitudinal direction remain, and the crystal grain size ratio a / b is out of the range of 0.9 to 1.4, and at least one of the minimum bending radius MBR / t of GW and BW exceeds 1, .

In addition, the mold for casting the ingot is made of copper. If the mold is made of a material other than copper (for example, cast iron, graphite, brick or the like), the coarse dregs remain in the ingot and finally the density of the particles A exceeds 1 / The bendability of the substrate is deteriorated.

The pass schedule is adjusted so that the temperature at the end of hot rolling becomes 600 ° C or higher. If the end temperature of the hot rolling is less than 600 ° C, the coarse structure remains in the rolling direction without causing dynamic recrystallization. Therefore, the crystal grain size ratio a / b is out of the range of 0.9 to 1.4, and at least one of the minimum bending radius MBR / t of GW and BW exceeds 1, and the bendability is deteriorated.

The finishing degree of the final pass of the hot rolling is set to 25 to 40%. If the degree of processing is less than 25%, the coarse structure remains in the rolling direction without causing dynamic recrystallization. Therefore, the crystal grain size ratio a / b is out of the range of 0.9 to 1.4, and at least one of the minimum bending radius MBR / t of GW and BW exceeds 1, and the bendability is deteriorated. If the degree of processing exceeds 40%, there is a fear of causing hot-rolled cracks.

The processing degree of the first cold rolling is set to 95% or more. If the processing degree of the first cold rolling is less than 95%, precipitation of Ni-P at the time of recrystallization annealing is insufficient and the particle B becomes less than 50 pieces / mm < 2 >

In the batch annealing, it is preferable to set the temperature of the recrystallization annealing to 380 to 500 ° C and the annealing time to 25 to 70 minutes. If the recrystallization annealing temperature is less than 380 DEG C, the non-recrystallized grains remain, and at least one of the minimum bending radius MBR / t of GW and BW exceeds 1 to deteriorate the bendability. Further, precipitation of the Ni-P compound becomes insufficient, and the particle B becomes less than 50 pieces / mm < 2 >, and the stress relaxation resistance deteriorates. When the recrystallization annealing temperature exceeds 500 占 폚, the crystal grain size becomes larger than 10 占 퐉, the strength is lowered and the Ni-P precipitates are also coarsened, so that the grain B exceeds 500 / mm & Is decreased, and the stress relaxation resistance is deteriorated.

If the annealing time of the recrystallization annealing is less than 25 minutes, the precipitation of the Ni-P compound is insufficient, the particle B becomes less than 50 pieces / mm < 2 >, and the stress relaxation resistance deteriorates. When the annealing time of the recrystallization annealing exceeds 70 minutes, the crystal grain size becomes larger than 10 mu m, the strength is lowered, and the Ni-P precipitates are also coarsened, so that the grain B exceeds 500 pieces / The precipitates contributing to the stress relaxation are reduced, and the stress relaxation resistance is degraded.

Further, recrystallization annealing can be performed in a continuous annealing furnace in order to further reduce the production cost. At this time, the annealing temperature is set to 550 to 800 占 폚, and the furnace stay time (agreement with the throughput rate) of the material is adjusted so that the crystal grain size becomes equal to or smaller than the target size (10 占 퐉).

The degree of the final cold rolling may be set arbitrarily in consideration of the desired tensile strength and bending workability, but is preferably 20% or more and 50% or less. Deformation removal annealing is carried out under conditions of 250 ° C or higher, and the conditions are adjusted so that the difference in tensile strength before and after annealing is within 50 MPa.

Further, by containing Ni and P in the alloy, the present invention can precipitate fine precipitates of Ni ₃ P even when the recrystallization annealing time is shortened as described above, thereby reducing the production cost and improving the strength and stress relaxation resistance Can be improved.

On the other hand, in order to reduce the stress relaxation rate to 25% or less, it is necessary to disperse Ni ₃ P of an appropriate size contributing to stress relaxation as a precipitate in the mother phase. When the cooling after the hot rolling is set as the cooling, precipitation of Ni ₃ P proceeds, but the size of Ni ₃ P is larger than that of the precipitate at a level contributing to stress relaxation. Therefore, it is possible to suppress the precipitation after the completion of the hot rolling and further sufficiently melt the Ni and P in the parent phase, thereby obtaining the Ni and P states in the material so as to precipitate Ni ₃ P at the next annealing and recrystallization annealing. Adjust. In order to employ Ni and P, the end temperature of hot rolling is set to 600 DEG C or higher, and the material is water-cooled after completion of hot rolling to suppress precipitation.

Example

≪ Experiment A (Examples 1 to 16, Comparative Examples 1 to 8) >

Electric copper was dissolved in an atmospheric melting furnace, and a predetermined amount of the additive element shown in Table 1 was added, and the molten metal was stirred. Thereafter, a mold made of copper was poured at a pouring temperature of 1170 ° C to obtain a copper alloy ingot having a composition shown in Table 1 with a thickness of 30 mm x width 60 mm x length 120 mm. After 2.5 mm of the ingot was subjected to 2.5 mm per side, hot rolling, cold rolling and heat treatment were carried out in the following order to obtain a sample having a thickness of 0.2 mm.

(1) The ingot was annealed at a holding temperature of 850 占 폚 for 3 hours (holding time) and then hot-rolled to a plate thickness of 11 mm to measure the material temperature (finish temperature of hot rolling) at 660 占 폚 , And then water-cooled.

(2) In order to remove the oxide scale of the surface layer after hot rolling, 0.5 mm surface was machined.

(3) The first cold rolling was carried out until the sheet thickness became 0.36 mm (the degree of processing was 97%).

(4) Recrystallization annealing was performed at 380 캜 for 30 minutes.

(5) Recrystallization After the oxidation scale of the surface after annealing was removed by pickling and buffing, final cold rolling was carried out until the plate thickness became 0.25 mm (processing degree 33.3%).

(6) After the final cold rolling, deformation-removing annealing at 300 DEG C x 0.5 h was performed.

≪ Experiment B (Inventive Examples 21 to 32, Comparative Examples 11 to 25) >

An ingot was obtained in the same manner as in Experiment A except that the composition of the ingot was Cu-0.4% Sn-10% Zn-1.0% Ni-0.05% P. However, the melt casting conditions of the ingot, the conditions of the hot rolling, the processing degree of the first cold rolling, and the annealing conditions of the recrystallization were changed as shown in Table 3. The final cold rolling was performed until the material having a thickness of 0.3 mm after the recrystallization annealing became 0.2 mm (degree of processing: 33.3%). Further, after the final cold rolling, deformation removal annealing at 300 deg. C x 0.5 h was carried out.

<Evaluation>

The following items were evaluated with respect to the materials after the deformation removal annealing of Experiments A and B. [ The copper alloy having small anisotropy in the present invention in the present invention means a copper alloy whose difference in tensile strength in the direction parallel to the rolling direction and in the direction perpendicular to the rolling direction and the difference in deformation coefficient is small according to the following criterion.

[Average crystal grain size and crystal ingot ratio a / b]

After a sample having a width of 20 mm and a length of 20 mm was electrolytically polished, a reflection electron image was observed with an FE-SEM manufactured by Philips. The observation magnification was 1000 times, and the crystal grain size was determined by the cutting method specified in JIS H 0501 for the image of 5 fields, and the average value was calculated. The average value of the crystal grain size a in the rolling parallel direction and the crystal grain size b in the direction perpendicular to the rolling direction were respectively determined, and the crystal grain size ratio a / b was calculated.

[Average crystal grain size and crystal ingot ratio a / b]

In order to measure the number density of the Ni-P system compound particles, the parallel cross section of the sample was polished by mechanical polishing using diamond abrasive grains having a diameter of 1 占 퐉, followed by electrolytic polishing with a phosphoric acid polishing solution. The surface of the sample after electrolytic polishing was observed by FE-SEM (Electron Radiation Scanning Electron Microscope: manufactured by PHILIPS Co., Ltd.) at a magnification of 500 times and 65 times for a particle A, The number of compound particles in the particle diameter range was measured by particle analysis software attached to the FE-SEM to obtain the number density. The reason why the components of the above-mentioned particles A and B are Ni-P based particles was confirmed by analyzing particles of typical shape (diameter) in each field using EDS (energy dispersive X-ray analysis) of FE-SEM .

[The tensile strength]

Tensile tests were conducted on GW and BW for each sample to determine tensile strength (TS) in accordance with JIS Z 2241. It was judged that the strength was good when the tensile strength was 500 MPa or more, and when the difference in tensile strength between GW and BW was 50 MPa or less, it was judged that the difference in strength was small.

[Conductivity]

The conductivity (% IACS) was calculated for each sample from the volume resistivity determined by the four-terminal method using a double bridge device in accordance with JIS H 0505.

[W bending property]

Short test specimens having a width of 10 mm and a length of 30 mm were sampled such that the sample longitudinal direction was parallel (GW direction) or perpendicular (BW direction) to the rolling direction. The test piece was subjected to a W bending test (JCBA-T307), and the minimum bending radius at which cracking did not occur was determined as MBR (Minimum Bend Radius), and the ratio was evaluated by the ratio MBR / t to the plate thickness t (mm). When MBR / t was 1 or less in both directions, it was judged that the bendability was good.

[Deformation Coefficient]

For each sample of GW and BW, the deformation coefficient was measured in accordance with the Japanese Industrial Standard of the Shin Dynasty Association (JCBAT312: 2002). When the difference between the deformation modulus of GW and BW was 10 ㎬ or less, it was judged that the difference in deformation modulus was small.

[Stress Relieving Characteristics]

A test piece having a width of 10 mm and a length of 100 mm was sampled so that the longitudinal direction of the test piece was parallel to the rolling direction. One end of the test piece was fixed and deformation of y ₀ was applied to the test piece at a position of 50 mm from the fixing position (l = 50 mm) as a point of action. The stress (? ₀ ) corresponding to 80% of the 0.2% . y ₀ was obtained from the following equation.

y ₀ = (2/3) · l ² · σ ₀ / (E · t)

Here, E is the deformation modulus (the value measured by the above method), and t is the thickness of the sample. In a state given the variation of y ₀ for test pieces and unloading at 150 ℃ after 1,000 hours heating, the permanent deformation rate (height) by measuring the y, the stress relaxation ratio {[y (㎜) / y 0 (㎜)] × 100 (% )}. When the stress relaxation rate was 25% or less, it was judged that the stress relaxation resistance was good.

The obtained results are shown in Tables 1 to 4. Tables 1 and 2 are the results of Experiment A, and Tables 3 and 4 are the results of Experiment B.

About experiment A

In which the content of Sn, Zn, Ni and P is within the specified range, the crystal grain size ratio a / b is in the range of 0.9 to 1.4, and the number density of the particles A and B as Ni- , The strength, the bendability and the stress relaxation resistance were kept good, and the anisotropy was reduced.

On the other hand, in Comparative Example 1 in which Zn was less than 3% and Comparative Example 3 in which Sn was less than 0.2%, the tensile strengths of GW and BW were all less than 500 MPa and the strength deteriorated.

In the case of Comparative Example 2 in which Zn exceeded 18%, the minimum bending radius MBR / t of BW exceeded 1, and the stress relaxation rate also deteriorated exceeding 25%.

In the case of Comparative Example 4 in which Sn was more than 0.8% and in Comparative Example 8 where P was more than 0.12%, cracks were generated by hot rolling, and an alloy could not be produced.

In Comparative Example 5 in which Ni was less than 0.3%, precipitation of Ni-P-based particles was insufficient and the stress relaxation rate deteriorated by more than 25%.

In the case of Comparative Example 6 in which Ni exceeds 1.2%, the minimum bending radius MBR / t of BW exceeded 1.

In Comparative Example 7 in which P was less than 0.01%, precipitation of Ni-P-based particles was insufficient and the stress relaxation rate deteriorated exceeding 25%.

About experiment B

In each of the examples in which the conditions of melt casting, hot rolling, first cold rolling, and recrystallization annealing of the ingot satisfy the specified ranges, the crystal grain size ratio a / b satisfies 0.9 to 1.4, and the Ni- The number density of the particles A and the particles B fall within a specified range and the strength, bendability, and stress relaxation resistance are kept good and the anisotropy is reduced.

On the other hand, in the case of Comparative Example 11 in which the ingot injection temperature was lower than 1150 占 폚, the casting surface of the ingot was roughened and surface abnormality occurred, and further production could not be performed. In the case of Comparative Example 12 in which the ingot temperature is higher than 1250 DEG C, the cast structure is coarsened, the crystal grain size ratio a / b is out of the range of 0.9 to 1.4 to increase the anisotropy and the minimum bending of GW and BW The bending property was deteriorated when the radius MBR / t exceeded all 1s.

In the case of Comparative Examples 13 to 15 in which the casting mold for casting the ingot was made of a material other than copper (cast iron, graphite or brick, respectively), the coarse dregs remained in the ingot, and the density of the particles A was 10 / Mm &lt; 2 &gt;, and the minimum bending radius MBR / t of GW and BW exceeded 1, and the bendability deteriorated.

In the case of Comparative Example 16 in which the end temperature of hot rolling was lower than 600 占 폚, coarse structure remained in the rolling direction without causing dynamic recrystallization. As a result, the crystal grain size ratio a / b deviates from the range of 0.9 to 1.4, resulting in an increase in anisotropy and deterioration of bending property when the minimum bending radius MBR / t of BW exceeds 1. In addition, since the amount of dissolved Ni and P was insufficient, precipitation of the Ni-P based particles became insufficient and the number density of the particles B became less than 50 pieces / mm &lt; 2 &gt;

In Comparative Example 17 in which the finishing degree of the final pass of the hot rolling was less than 25%, the coarse structure remained in the rolling direction without causing dynamic recrystallization. As a result, the crystal grain size ratio a / b deviates from the range of 0.9 to 1.4, resulting in an increase in anisotropy and deterioration of bending property when the minimum bending radius MBR / t of BW exceeds 1. On the other hand, in the case of Comparative Example 18 in which the final pass processing degree of the hot rolling exceeds 40%, hot cracking was caused, and further production could not be carried out.

In Comparative Example 19 in which the degree of processing of the first cold rolling was less than 95%, precipitation of Ni-P at the time of recrystallization annealing became insufficient, the number density of the particles B became less than 50 pieces / mm 2, .

In the case of Comparative Example 20 in which the temperature of the recrystallization annealing is lower than 380 占 폚, recrystallization does not sufficiently take place and the non-recrystallized region remains in most of the observation region, and the minimum bending radius MBR / t of GW and BW exceeds 1 both, .

In the case of Comparative Example 21 in which the temperature of the recrystallization annealing was higher than 500 캜, the crystal grain size exceeded 10 탆 and the tensile strength of GW and BW decreased to less than 500 MPa. Further, the number density of the particles B exceeded 500 pieces / mm &lt; 2 &gt; and the fine precipitates contributing to stress relaxation were reduced, resulting in deterioration in stress relaxation resistance.

In the case of Comparative Example 22 in which the annealing time of the recrystallization annealing was less than 25 minutes, precipitation of Ni-P type particles was insufficient and the number density of the particles B became less than 50 pieces / mm &lt; 2 &gt; In the case of Comparative Example 23 in which the annealing time of the recrystallization annealing was more than 70 minutes, the crystal grain size exceeded 10 占 퐉 and the tensile strength of GW decreased to less than 500 MPa. Further, the number density of the particles B became 500 pieces / mm &lt; 2 &gt; or more, and the fine precipitates contributing to the stress relaxation decreased, resulting in deterioration in stress relaxation resistance.

Claims (3)

Wherein the alloy contains 0.2 to 0.8% of Sn, 3 to 18% of Zn, 0.3 to 1.2% of Ni, and 0.01 to 0.12% of P, the balance being Cu and inevitable impurities,
The crystal grain size ratio a / b when the crystal grain size in the rolling parallel direction is a, the crystal grain size b in the direction perpendicular to the rolling direction is 0.9 to 1.4, and the number density of Ni-P system compound particles in the cross- Cu-Zn-Sn-Ni-P alloy.
(1) Ni-P-based compound particles A having a particle size of 2.0 m or larger are 10 particles / mm 2 or less
(2) Ni-P based compound particles B having a diameter of 100 nm or more and 500 nm or less of 50 / mm 2 or more and 500 / mm 2 or less The method according to claim 1,
The tensile strength of both GW and BW is 500 MPa or more, the difference in tensile strength between GW and BW is 50 MPa or less, the minimum bending radius MBR / t of GW and BW is all 1 or less and the difference in deformation constant between GW and BW is 10 Cu-Zn-Sn-Ni-P alloy. 3. The method according to claim 1 or 2,
Cu-Zn-Sn-Ni-P alloy containing at least one selected from the group consisting of Mg, Mn, Ti, Cr and Zr in a total amount of 0.02 to 0.25 mass%.