JP2003293056A - Phosphor bronze strip with excellent press workability - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a high-strength copper alloy used for electronic parts such as terminals and connectors, and particularly a high-strength phosphor bronze strip. <P>SOLUTION: There are proposed: (1) a phosphor bronze strip which can be excellently punched and which has a composition containing 20 to 100 ppm S and ≤50 ppm, in total of Mn, Ca, Mg and Al; (2) a phosphor bronze strip which can be excellently punched and in which, when etching is applied to the cutting face parallel to the rolling direction, the sum total of the lengths of etching traces is ≥5 mm/mm<SP>2</SP>; (3) a phosphor bronze strip which can be excellently punched and in which a copper sulfide phase ranging from 1 to 3% exists in the metallic structure in the cutting face parallel to the rolling direction; and (4) a phosphor bronze strip which is composed of any of the strips (1) to (3) and in which plastic deformation ratio is ≤50% when a shearing test is performed at 4 to 10% clearance. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high-strength copper alloy, especially a high-strength phosphor bronze strip used for electronic parts such as terminals and connectors.

[0002]

2. Description of the Related Art Phosphor bronze such as C5210 and C5191 (JIS alloy number) or copper alloy such as C2600 (JIS alloy number) have excellent workability and mechanical strength, and are therefore used as terminals and connectors for electronic parts. It is widely used in applications such as. On the other hand, in recent years, the progress of lightness, thinness, and miniaturization of parts has been more remarkable than ever, and along with this, there is an increasing need for high-strength copper alloys such as beryllium copper, titanium copper, and Corson alloy. However, as copper alloys for electronic parts, these relatively high-strength copper alloys, which are relatively new, have restrictions on supply and demand in the market and distribution, and there is a problem in, for example, a market that emphasizes global standards. It is also not preferable that these high strength copper alloys are more expensive than conventional copper alloys such as phosphor bronze. From these perspectives,
Phosphor bronze, which has been said to have high mechanical strength among copper alloys, has been required to have further improved strength and workability.

For workability, punching and bending are particularly important. When punching is repeatedly performed by the press, the punch of the press is worn by the material, and the shear surface morphology deteriorates. Therefore, after pressing a certain number of times, it becomes necessary to grind and readjust the mold. Since the pressing speed is also faster from the viewpoint of improving productivity, the importance of materials with less die wear during punching is becoming more and more important. Further, due to the downsizing of the contacts, the material is subjected to severe bending with a high strength and a small bending radius, so that cracks are likely to occur in the bent portion. In addition, punchability and bendability are contradictory properties,
From a sensory point of view, a brittle material is easy to punch, but it is easily cracked, and a viscous material is easy to bend, but the punchability is poor and the mold wear tends to be fast.

[0004]

SUMMARY OF THE INVENTION It is an object of the present invention to improve the press workability, particularly punchability and bendability, required for press working of electronic parts such as connector terminals in a phosphor bronze strip. Further, a technique for increasing the strength while maintaining these is provided.

[0005]

The present inventors have dramatically improved the press workability by adjusting the composition, structure, and processing conditions of the phosphor bronze strip. That is, (1) S: 20 to 100 pp in mass ratio (ppm)
The total content of m, Mn, Ca, Mg, Al is 50 pp
A phosphor bronze strip excellent in punching characteristics, characterized by having a length of m or less. (2) When etching a cut surface parallel to the rolling direction, the total length of etching marks is 5 mm / mm.
Phosphor bronze strip with excellent punchability, characterized by ² or more. (3) A phosphor bronze strip having excellent punchability, characterized in that the copper sulfide phase is present in the range of 1 to 3% in the metal structure of the cut surface parallel to the rolling direction. (4) The phosphor bronze strip of (1) to (3), which has a plastic deformation ratio of 50% or less when subjected to a shear test with a clearance of 4 to 10%.

(5) Mass ratio (ppm), S: 20
~ 100 ppm, the total content of Mn, Ca, Mg, Al is 50 ppm or less and Zn is 100 to 1000 ppm
A phosphor bronze strip that is excellent in both bendability and punchability, which is characterized by containing it.

(6) The average grain size (mGS) after annealing at 425 ° C. for 10,000 seconds is 5 μm or less, and the standard deviation (σGS) of variations in the grain size is 1/3 mG.
Phosphor bronze strip having excellent bendability and punchability, characterized in that the difference between the tensile strength and the 0.2% proof stress of the cold rolled copper alloy strip is S or less and is 80 MPa or less. . (7) The average grain size (mGS) after annealing at 425 ° C. for 10,000 seconds is 5 μm or less, and the standard deviation (σGS) of variations in the grain size is 1/3 mGS or less, and the cold rolling is performed. The difference between the tensile strength and the 0.2% proof stress of the formed copper alloy strip was within 80 MPa, and both the bendability and the punchability were excellent (1) to
The phosphor bronze strip described in (5).

(8) A cold rolled strip having a workability of 45% or more is finally recrystallized and annealed so that the crystal grain size (mGS) is 3 μm or less and the variation standard deviation (σGS) thereof is 2 μm or less. A phosphor bronze strip excellent in both bendability and punchability, which is characterized by being subjected to a final cold rolling of 10 to 45%. (9) A cold-rolled strip having a workability of 45% or more is finally recrystallized and annealed so that the crystal grain size (mGS) is 3 μm or less and the variation standard deviation (σGS) is 2 μm or less, and subsequently the workability is 10 to 45. % Final cold rolling, the phosphor bronze strip excellent in both bendability and punchability described in (1) to (5).

(10) A cold-rolled material having a tensile strength of TS ₀ (MPa), which has been subjected to final cold rolling with a workability of X (%),
Phosphor bronze having excellent bendability and punchability according to any one of items 1 to 9, characterized in that strain relief annealing is performed until the tensile strength TS _a (MPa) becomes TS _a <TS ₀ −X. Article.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION (1) In punching,
In the process in which the plate material is sheared by the punch and the die, that is, in the punch stroke process, a crack starting point is formed in the shear deformation portion. The crack propagates through the shear deformation portion starting from this crack start point and penetrates the plate to perform punching. Until the crack begins, the punch and die cutting edges rub strongly against the surface of the material. At this time, the blade edge of the die is subject to adhesive wear with the material surface and scratch abrasion due to foreign particles, and the blade edge is gradually worn away. Therefore,
Cracks should be formed as soon as possible during the shearing process.

On the other hand, when S is present in phosphor bronze, S
Since Cu has a low solid solubility in phosphor bronze (see the phase diagram), a Cu ₂ S phase appears in the mother phase. Since this phase is more brittle than the parent phase, it can be the starting point of cracks prior to the parent phase during shear deformation. By adding 20 ppm or more of this S, it is possible to cause the crack start point to be accelerated. Basically, the higher the S content, the better, but 1
If added in excess of 00 ppm, bending workability in plate and strip products and rolling processability in the production process of strip products are deteriorated, so the addition amount is set to 100 ppm or less. In addition, S is added as a raw material such as copper sulfide at the time of melting the phosphor bronze ingot, casting, and charcoal in contact with the molten metal,
Since it is also contained in the carbon raw material and the press oil extreme pressure agent in scrap, it is also effective to intentionally control the mixture from these.

Mn, Ca, Mg and Al are not usually added elements of phosphor bronze but enter as a contaminant in the manufacturing process as described above.
When it is contained in an amount of 0 ppm or more, it is impossible to stably disperse the above-described Cu ₂ S phase in a state of having a function as a crack starting point, so it is necessary to control the total to 50 ppm or less.

(2) On the other hand, in the sulfide phase containing copper sulfide, when the cross section of the material is etched with a sulfuric acid-based etching solution or the like, the same portion is preferentially etched to form fine recessed marks in a pit shape. When this cross section is observed with a dark field image of an optical microscope, etching marks are white and scattered in dots or lines. The cut surface parallel to the rolling direction was etched with an aqueous solution of sulfuric acid at room temperature for about several seconds to 30 seconds, and the total etching length observed by the above method was 5 mm or more per 1 mm ^{2 of} cross-sectional area. For the same reasons as in (1) and (1), the punchability of the phosphor bronze strip is remarkably improved.

(3) Further, the thickness of the copper sulfide phase is obtained from the cross section parallel to the rolling direction by the following method,
The area ratio of the copper sulfide phase can be estimated. EPMA
Acceleration voltage of 15kV, electron beam diameter on the sample surface is 1μ
X of sulfur when the beam crosses the copper sulfide phase after adjusting to m
Measure the change in line intensity. The distance until the X-ray intensity rises from the background, draws a peak, and returns to the background again is defined as the thickness of the copper sulfide phase. The length of the copper sulfide phase was measured from the SEM photograph to determine the area of the copper sulfide phase. As a result, the total area of the copper sulfide phase is 1 to 3 of the total.
It is good to set it as%. This is because improvement in punching property is not observed below that and adverse effects such as decrease in bendability become a problem above that. Note that (1) to (3) are common in that they try to utilize the effectiveness of the Cu ₂ S phase inside the phosphor bronze as a crack initiation point during shear deformation,
Each of them has a correlation but does not always have a unique correlation. That is, even for phosphor bronze having the same S content, the amount of solid solution, the form of the copper sulfide phase, and the distribution state differ depending on the combination of heat treatment and rolling in the manufacturing process.

(4) The quality of the punchability can be specified by the plastic deformation rate obtained from the plastic deformation amount by the shear test. The amount of plastic deformation is a punch moving distance at which a crack starting point is formed in the shear deforming portion, the starting point serves as a starting point, and the crack propagates through the shear deforming portion and penetrates the plate. The plastic deformation ratio is a value (%) obtained by dividing the amount of plastic deformation by the plate thickness of the material, and has universality. In the shear test, the upper die (punch) of the shear tester is attached to the crosshead of the tensile tester, and this is lowered to punch a hole of a certain diameter in the material on the die, and the punch stroke at this time is measured with an extensometer. The punch load is measured by a load cell of a tensile tester, and a displacement-load curve is created. Displacement −
In the load curve, the initial linear portion corresponds to the elastic deformation region, and after the shear deformation thereafter, the load linearly drops when the fracture occurs. The amount of plastic deformation is the distance between the point that deviates from the initial straight line in the elastic deformation region and the point that deviates from the load drop line at the time of breaking. Since the influence of the clearance on the material plate thickness is large in measuring the amount of plastic deformation, it is necessary to select the punch so that the clearance is 4 to 10%.
A phosphor bronze strip having a plastic deformation ratio of 50% or less can reduce die wear during high-speed pressing for processing a connector contact or the like.

(5) S: 20 to 100 ppm, Mn,
As described above, the phosphor bronze characterized in that the total content of Ca, Mg, and Al is 50 ppm or less has good punchability by interspersing the copper sulfide phase in the mother phase. In phosphor bronze obtained by adding 100 to 1000 ppm of Zn to this alloy, a part of copper sulfide is changed to zinc sulfide,
Fragmentation of the sulfide phase is promoted during thinning by repeated rolling and annealing. Due to the division of the sulfide phase, the bendability is improved, and phosphor bronze having excellent punchability and bendability can be obtained. When Zn is 100 ppm or less, the change to zinc sulfide is small, and therefore the bendability is not improved. When Zn is 1000 ppm or more, the punching property deteriorates due to the decrease of the copper sulfide phase, so the addition amount is preferably 1000 ppm or less.

(6) Phosphor bronze strips have an average crystal grain size (mGS) of 5 μm or less after annealing at 425 ° C. for 10,000 seconds, and a standard deviation (σG) of variations in the crystal grain size.
S) is 1/3 mGS or less, and the difference between the tensile strength and 0.2% proof stress of the cold rolled phosphor bronze strip is 8
It is specified to be within 0 MPa. In the present invention, the crystal grain size is measured by a cutting method according to JIS H0501. Specifically, the number of crystal grains completely traversed by a straight line segment of a predetermined length was counted, and the average value of the cut lengths was taken as the crystal grain size. The standard deviation, which is an index of the variation, is not the standard deviation of the cutting length but the standard deviation of the crystal grain size.

In the final product, which has been strengthened by grain boundary strengthening and dislocation strengthening, that is, heat treatment and rolling, crystal grain boundaries cannot be revealed. When a metal strip is deformed by cold working, the difference in local deformation inside the crystal grains becomes remarkable with the progress thereof, and various deformation bands such as shear bands and micro bands appear. Due to these deformation zones, the grain boundaries formed by recrystallization before cold working become discontinuous, and even if the cross section is etched and observed with an optical microscope, the crystal structure becomes unclear. Even when the cold working ratio is about 20%, when observing the structure with a transmission electron microscope image, it is observed that some of the recrystallized grain boundaries before the cold working remain, but it is already covered by the cell structure. Therefore, the grain size cannot be accurately specified. This is a major obstacle to improving the properties of the cold rolled material.

In the present invention, the recrystallization behavior after cold working is
It has been found that there is a correlation with the properties of phosphor bronze, which has both bendability and strength. This correlation is effective in identifying the material. That is, the copper alloy of the present invention has a difference in tensile strength and 0.2% proof stress of 80 MPa or less, and also has excellent bendability, and further has an average crystallinity when annealed at 425 ° C. for 10,000 seconds. The grain size (mGS) is 5 μm or less, and the standard deviation (σGS) of the crystal grain size is 1/3 mGS or less.

Generally, when cold working is performed after annealing to increase the workability, the difference between the tensile strength and the 0.2% proof stress decreases, but along with that, the ductility decreases and the bending Cracks easily occur during processing. However, the present invention has found that the ductility is less reduced by adjusting the final annealing condition before the final rolling and the cold working condition before the final rolling. Phosphor bronze products with an average crystal grain size (mGS) of 5 μm or less are annealed under the condition of 425 ° C. × 10,000 seconds where the crystal grain size of the conventional phosphor bronze grows greatly. Combine. More desirably, the average crystal grain size (m
When GS) is 3 μm or less, the relationship between tensile strength and bendability is further improved. However, the average grain size (mGS)
If the crystal grain size varies even if is less than 5 μm,
Its effect is low. As will be described later, the manufacturing method must be strictly controlled to form a uniform fine structure. The allowable range of the variation is the standard deviation of the crystal grain size, which is 1/3 mGS
Must be: Standard deviation (σGS) is 1 /
This is because if it exceeds 3 mGS, the effect of improving bendability is small. The phosphor bronze having the characteristics of this condition has both press punching property and bendability.

(7) In the inventions (1) to (4), only the punchability is improved, so that a slight decrease in bendability cannot be avoided. By combining the characteristics of (6), both punching property and bendability can be significantly improved.

(8) The present invention relates to a method for producing a high-strength phosphor bronze strip. In a phosphor bronze strip manufactured by repeating cold rolling and annealing, the present invention relates to a method for manufacturing high-strength phosphor bronze which defines the final cold rolling, the final annealing before that, and the cold rolling step before that. The present invention aims to increase the strength by refining the crystal grains in the final annealing. The material thickness before cold rolling is t _0, and the material thickness after cold rolling is t, X = (t ₀ −t) / t ₀ × 100 (%)
The degree of cold rolling workability X defined by the above is set to 45% or more. If X is less than 45%, the crystal grain size after final annealing is difficult to be refined even if the heat treatment conditions of final annealing are adjusted. Because. Further, the average grain size (mGS) after annealing is set to 3 μm or less and the standard deviation (σGS), which is the variation of the grain size, is set to 2 μm or less, because the heating temperature profile during annealing is strictly controlled. This is because it is necessary to have a uniform fine crystal grain structure. Strictly speaking, the crystal grain size is not normally distributed, but when the average crystal grain size (mGS) is 3 μm and the standard deviation (σGS) is 2 μm, 99% or more of the individual crystal grain sizes are mGS + 3σ, that is, 9 μm or less. It means that. Further, it is not always preferable that crystal grains having a diameter of 8 μm or more are mixed in the recrystallized structure, and it is desirable that the standard deviation of the crystal grain size is 1.5 μm or less.

As the cold rolling workability before the final annealing is increased, the grain size of the recrystallized structure after the final annealing is apt to be small, but at the same time, the nucleation and the secondary recrystallization behavior thereafter are largely varied, and thus the mixed grains are mixed. It becomes easy to become. This tendency is particularly strong in a copper alloy having a pure copper type recrystallized structure with a high copper concentration. On the contrary, in the case of phosphor bronze containing 4 mass% or more of Sn, the recrystallized grains after relatively strong working are likely to be sized. Taking these factors into consideration, it is necessary to optimize the annealing conditions, that is, the temperature, time, and temperature profile for each alloy system to obtain the above recrystallized structure. If the average crystal grain size is out of the range of 3 μm or less and the standard deviation thereof is 2 μm or less, high work hardening ability in the final cold rolling cannot be obtained. Average grain size is 3
When the final cold working with a working ratio of 10 to 45% is carried out in a state of not more than μm and its standard deviation of not more than 2 μm, a copper alloy having high strength and excellent bendability is obtained. When the workability is less than 10%, even a conventional copper alloy having an average crystal grain size after final annealing of about 10 μm has good bendability and the grain refining effect is small. Further, if the workability exceeds 45%, the bendability is lowered, and the range of use as a metal member such as a contact to be bent is narrowed.

(9) In the inventions (1) to (4), only the punching property is improved, so that a slight decrease in bendability cannot be avoided. By combining the characteristics of (8), both punching property and bendability can be significantly improved.

(10) In the above copper alloy, stress relief annealing is performed after final rolling, and the amount of decrease in tensile strength in the stress relief annealing is regulated. The regulation is the tensile strength before strain relief annealing. Is TS ₀ (MPa), and the tensile strength after strain relief annealing is T
As S _a (MPa), TS _a <TS ₀ −X (working ratio (%) of final cold rolling). Phosphor bronze, nickel silver, etc. may be subjected to stress relief annealing. The stress relief annealing is different from the recrystallization annealing performed before the final rolling, for the purpose of recovering the ductility (workability) lowered by cold working and also improving the spring property, for example, a phosphor bronze for spring ( C5210: JIS
H 3130) and the like. This strain relief annealing can be performed as necessary with a tension annealing line or the like after the final rolling. That is, the phosphor bronze according to the above invention has higher strength and better bendability than the phosphor bronze produced by the conventional technique even after the strain relief annealing. Further, when an annealed material having a small grain size is cold-rolled, it is effective to perform strain relief annealing according to the final workability in order to recover ductility. In particular, to improve bendability, the final cold rolling workability is set to X% and the tensile strength TS
_For the cold rolled material of ₀ (MPa), strain relief annealing is performed under the condition that the tensile strength TS _a (MPa) after strain relief annealing is TS _a <TS ₀ −X. For example, 80 at the final processing rate of 50%
In the case of a cold-rolled material that has been work hardened to 0 MPa, strain relieving annealing of this material and strain relieving annealing to less than 750 MPa can provide a material with good bendability.

[0026]

EXAMPLES (1) Example 1 This is an example of the invention according to claims 1 to 4. Based on phosphor bronze having the composition shown in Table 1, S, Mn, Ca, M
g and Al were added, and charcoal was coated and melted in the atmosphere and then cast to prepare an ingot having a size of 100 mm ^W × 40 mm ^t × 150 mm ¹ . This ingot is made into 75% N ₂ + 25% H ₂
After homogenizing and annealing at 700 ° C. for 1 hour in the atmosphere, the tin segregation layer on the surface was removed by grinding with a grinder, and the components were analyzed. Thereafter, cold rolling and recrystallization annealing were repeated a plurality of times as needed to obtain a plate having a thickness of 0.2 mm. The degree of cold rolling before the final annealing, the grain size in the final recrystallization annealing, the degree of the final cold rolling and the like were set to be the same so as not to cause a difference in the working history. Table 1 shows the component values, the total etching trace length measured by etching the cross section of the plate, the area ratio of the copper sulfide phase measured by EPMA, and the plastic deformation ratio obtained by the shear test. Compared with the comparative example, the example of the present invention has a low plastic deformation ratio and good press punchability.

[0027]

[Table 1]

(2) Embodiment 2 This is an example relating to the invention according to claim 5. Based on the composition of phosphor bronze, with S, Mn, Ca, Mg, Al, and Zn added, the cold rolling process before final annealing and the final recrystallization annealing are performed so that there is no difference in processing history. A test piece was prepared in the same manner as in Example 1 with the same crystal grain size, final cold rolling workability, and the like. The bendability (r / t) is 10 mm ^w x 100 mm ^l . A test piece having a size of 10 mm ^w x 100 mm ^l is sampled at right angles to the rolling direction, and a W bending test (JIS H 3110) is performed at various bending radii. (R (bending radius) / t (test piece thickness)) was determined. The bending axis of the W bending test is parallel to the rolling direction.
In the comparative example, the one having a low plastic deformation ratio has a large r / t, and the one having a small r / t has a high plastic deformation ratio, but the present invention example has a low plastic deformation ratio and a small r / t. Excellent punchability and bendability.

[0029]

[Table 2]

(3) Third Embodiment This is an example of the invention according to claim 6. Using phosphor bronze having the composition shown in Table 3, a test piece was prepared in the same manner as in Example 1 without adding S, Mn, Ca, Mg, Al and Zn. However, in Example 3, the cold rolling workability before the final annealing, the crystal grain size in the final recrystallization annealing, the final cold rolling workability and the like were adjusted to cause a difference in working history. The characteristics are shown in Table 3. Tensile strength (TS: MPa), 0.2%
The proof stress (YS: MPa) is 13B test piece (JIS Z
2201) was sampled in parallel with the rolling direction and the tensile test (JI
S Z2241).

The crystal grain size is determined by the cutting method (JIS H 050
According to 1), the number of crystal grains that are completely cut by a line segment of a predetermined length is counted, and the average value of the cut length is defined as the crystal grain size. The standard deviation (σGS) of the crystal grain size is It is the standard deviation. That is, the cross-sectional structure perpendicular to the rolling direction was magnified 4000 times by a scanning electron microscope image (SEM image), and in a straight line segment having a length of 50 μm, 1 was calculated from the number of intersections of the line and the grain boundary. The value obtained by dividing the line segment by the subtracted value is defined as the crystal grain size, and the average of the crystal grain sizes obtained by measuring the 10 line segments is the average crystal grain size (Mg
S), and the standard deviation of each crystal grain size was defined as the standard deviation (σGS) in the present application. As compared with the comparative example (conventional material), the inventive example has good punching property and bendability as long as the strength is the same.

[0032]

[Table 3]

(4) Fourth Embodiment This is an example of the invention according to claim 7. For the coils of the components 1 to 16 shown in the invention examples of Tables 1 and 2, the cold rolling workability before final annealing, the crystal grain size in the final recrystallization annealing, the final cold rolling workability, etc. are adjusted. Then, the test piece was adjusted by the same method as in Example 3 in which a difference in processing history was generated. As compared with the comparative example (conventional material), the inventive example has good punching property and bendability as long as the strength is the same.

[0034]

[Table 4]

(5) Example 5 The invention according to claim 8 was verified. Table 3 shows the results. Comparative example is a conventional example, cold rolling workability before final annealing, the average crystal grain size in the final annealing is an example deviating from the present invention, the present invention example, compared to the conventional material of the comparative example, It has high strength, low r / t, and good bendability.

[0036]

[Table 5]

(6) Example 6 The effect of the stress relief annealing of claim 10 was investigated. Table 6 shows the survey results. The test pieces produced in Examples 3 to 5 were subjected to strain relief annealing under various conditions to evaluate the characteristics. The amount of decrease in tensile strength (TS) due to strain relief annealing is also shown. Invention Example No. 39, 41, 43, 45 and Comparative Example Nos. 27 is a material having a tin concentration of 8.0 to 8.2 mass%. The tensile strength (TS) of the example of the present invention is 721 to 85.
While 0 MPa and bendability (r / t) are 0.5,
In the comparative example, the tensile strength (TS) is 755 MPa and the r / t is 1, indicating that the present invention has high strength and good bendability. In addition, invention example No. 40, 42, 44, 46 and Comparative Example No. No. 28 is a material having a tin concentration of 10.0 to 10.2 mass%, and the tensile strength (TS) of the invention example is 820 to 85.
Whereas 9 MPa and bendability (r / t) are 0.5,
In the comparative example, the tensile strength (TS) is 830 MPa and the r / t is 1.5, which shows that the present invention has high strength and good bendability. As described above, by performing the strain relief annealing, the material of the present invention has distinctly higher strength than the conventional material of the comparative example, and the bendability can be improved. That is, if the strength is about the same, the bendability is remarkably improved. Further, if the bendability is the same, a significant increase in strength can be obtained.

[0038]

[Table 6]

[0039]

According to the present invention, it is possible to increase the strength without impairing the bendability of phosphor bronze, and to achieve the high level characteristics required for copper alloys for terminals and connectors for electronic parts. Was chosen. In addition, high tin phosphor bronze (Cu-10ma
ss% Sn-P: CDA52400) has made it possible to enter the field of high-strength copper alloys, which is an exclusive market for beryllium copper and the like, which could not enter due to poor bendability.

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Claims (10)

[Claims] 1. A mass ratio (ppm) of S: 20 to 10
The total content of 0 ppm, Mn, Ca, Mg, Al is 5
A phosphor bronze strip excellent in punching characteristics, characterized by being 0 ppm or less. 2. When etching a cut surface parallel to the rolling direction, the total length of etching marks is 5 mm.
/ Mm ² or more, a phosphor bronze strip with excellent punching characteristics. 3. A phosphor bronze strip having excellent punchability, wherein the copper sulfide phase is present in the range of 1 to 3% in the metal structure of the cut surface parallel to the rolling direction. 4. The phosphor bronze strip according to claim 1, which has a plastic deformation ratio of 50% or less when subjected to a shear test with a clearance of 4 to 10%. 5. A mass ratio (ppm) of S: 20 to 10
The total content of 0 ppm, Mn, Ca, Mg, Al is 5
A phosphor bronze strip excellent in both bendability and punchability, which is characterized by containing 0 ppm or less and 100 to 1000 ppm of Zn. 6. The average grain size (mGS) after annealing at 425 ° C. for 10,000 seconds is 5 μm or less, and the standard deviation (σGS) of variations in the grain size is 1/3 mGS or less, and A phosphor bronze strip excellent in both bendability and punchability, characterized in that the difference between the tensile strength and 0.2% proof stress of the cold rolled copper alloy strip is within 80 MPa. 7. The average grain size (mGS) after annealing at 425 ° C. for 10,000 seconds is 5 μm or less, and the standard deviation (σGS) of variations in grain size is 1/3 mGS or less, and The phosphor bronze excellent in both bendability and punchability according to claim 1, wherein the difference between the tensile strength and the 0.2% proof stress of the cold-rolled copper alloy strip is within 80 MPa. Article. 8. A cold-rolled strip having a workability of 45% or more is finally recrystallized and annealed so that the crystal grain size (mGS) is 3 μm or less and the variation standard deviation (σGS) thereof is 2 μm or less. A phosphor bronze strip excellent in both bendability and punchability, which is characterized by being subjected to a final cold rolling of 45%. 9. A cold-rolled strip having a workability of 45% or more is finally recrystallized and annealed to have a crystal grain size (mGS) of 3 μm or less and a variation standard deviation (σGS) of 2 μm or less. A phosphor bronze strip excellent in both bendability and punching property according to claim 1, which has been subjected to final cold rolling of up to 45%. 10. A cold-rolled material having a tensile strength of TS ₀ (MPa) subjected to final cold rolling with a workability of X (%), and a tensile strength TS _a (MPa) of TS _a <TS ₀ −. The phosphor bronze strip excellent in both bendability and punching property according to claim 1, which is subjected to stress relief annealing until it becomes X.