JP2002294369A - High strength copper alloy and production method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inexpensive copper alloy sheet or bar which has characteristics equal to or above those of Be copper in mechanical properties, spring critical value, bending workability or the like. SOLUTION: The high strength copper alloy sheet or bar has a composition containing, by mass, 8.5 to 10.5% Ni, 1.8 to 2.8% Sn, 0.005 to 0.05% Mn, 0.0001 to 0.005% Mg, 0.01 to 5% Zn, 0.0005 to 0.005% Pb and 0.0003 to 0.003% S, and in which the content of C is controlled to <=0.004%, H to <=0.0002%, and 0 to <=0.004%, and the balance Cu with inevitable impurities. In the rolling face of the sheet or bar, provided that the average crystal grain size (a) measured in the sheet width direction is 5 to 20 μm, and also, the average crystal grain size measured in a direction parallel to the rolling direction is (b), its aspect ratio b/a is controlled to 2.5 to 10.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a terminal, a connector,
The present invention relates to a high-strength copper alloy used for a wire harness, a terminal, a relay, a switch, a spring material, and the like, and a method for manufacturing the same.

[0002]

2. Description of the Related Art Conventionally, the above-mentioned uses include a spring phosphorus.
Bronze (C5212: Cu-8.0Sn-0.1P), C
725 (Cu-9.2Ni-2.3Sn), Be copper alloy
(CDA17410: Cu-0.3Be) is used
Came. Typical mechanical properties of the copper alloy sheet or strip
Is as follows. For phosphor bronze for springs, tension
Strength: 706 N / mm², 0.2% proof stress: 627 N /
mm², Spring limit value: 539 N / mm², Growth: 16%
In C725, tensile strength: 612 N /
mm², 0.2% proof stress: 575 N / mm², Spring limit
Value: 560 N / mm ², Elongation: 17%. Be copper
(CDA17410) has a tensile strength of 800 N / mm.
²Above, 0.2% proof stress: 700 N / mm²Above, spring limit
Boundary value: 700 N / mm²Elongation: 10% or more
High-grade spring with high strength and excellent bending workability
It is used as a material.

[0003]

Recently, the use of this field has been rapidly expanding due to the spread of mobile phones and personal computers, but the environmental problem of Be (Be is easily oxidized and produced Because oxides are harmful to the human body), the production process of Be copper, such as melting and casting, requires careful attention. In particular, melting and casting requires special equipment, so the production volume is limited. However, the shortage of supply has become a problem with the increase in demand in the previous term. To respond to these needs, Cu-10% Sn, Cu-Ni-Si-Sn
Alloys and the like have been proposed. However, is inferior in bending workability as compared with Be copper, and has large anisotropy of mechanical properties in a direction parallel to and perpendicular to the rolling direction. In particular, since the bending radius at which cracks do not occur when the bending line is bent so as to be parallel to the rolling direction is large, it is difficult to apply to applications that require fine bending. In addition, although a material having a strength comparable to that of Be copper can be manufactured by devising a composition and a manufacturing process, Be copper cannot be replaced because it does not reach Be copper due to a spring limit value or the like.

An object of the present invention is to provide an inexpensive copper alloy having the same properties as Be copper in properties such as mechanical properties, spring limit values, bending workability and the like, and a method for producing the same.

[0005]

DISCLOSURE OF THE INVENTION The copper alloy according to the present invention comprises:
Ni: 8.5 to 10.5%, Sn: 1.8 to 2.8%,
Mn: 0.005 to 0.05%, Mg: 0.0001 to
0.005%, Zn: 0.01 to 5%, Pb: 0.00
05-0.005%, S: 0.0003-0.003%
And C: 0.004% or less, H: 0.00
O: 0.004% or less, with the balance being Cu and unavoidable impurities.

A copper alloy sheet or strip according to the present invention is made of the above copper alloy, and has a rolled surface of the sheet or strip having an average crystal grain size a of 5 to 20 μm measured in the sheet width direction, and When the average grain size measured in a direction parallel to the direction is b, the aspect ratio b / a is 2.5 to 10, or / and the value of proof stress (σ0.2) / tensile strength (σB). Is 0.
It is characterized by having 9 or more. As a method of manufacturing the high-strength copper alloy sheet or strip, performing a short annealing with recrystallization during cold rolling, and performing a short annealing that does not completely recrystallize after further cold rolling, Further, it is characterized in that after cold rolling, annealing is performed to cause spinodal decomposition. Subsequent to this step, distortion correction by tension leveling may be further performed.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The copper alloy for terminals and connectors according to the present invention will be described in detail below. First, the reason for adding each additive element and the reason for limiting the composition will be described. (Ni) When Ni is contained together with Sn, strength, a spring limit value, fatigue characteristics, and the like are improved. However, if the content is less than 8.5%, no effect can be obtained, and if the content exceeds 10.5%, no further effect can be expected, resulting in a reduction in hot workability and cost. Also disadvantageous. Therefore, the amount of Ni added is 8.5 to 10.5%.
And (Sn) When Sn is contained together with Ni, the effect of improving mechanical properties, in particular, the balance between proof stress and elongation, and further improving the formability, spring limit value, and fatigue properties is obtained. Effect is not obtained. Conversely, if the content exceeds 2.8%, the hot workability decreases,
More economical. Therefore, the content of Sn is 1.8 to
2.8%.

[0008] (Mn) In the melting and casting process, S and O easily enter from the raw material, atmosphere, etc.
Mn fixes S and O in the form of a stable compound in the mother phase and performs deoxidation and desulfurization to improve hot workability. Further, Mn has an effect of improving heat resistance. If the content of Mn is less than 0.005%, the above effect is not sufficient. On the other hand, if the content exceeds 0.05%, the weatherability of the solder deteriorates and the reliability decreases. Therefore, Mn
The content is 0.005% to 0.05%. (Mg) Mg, like Mn, fixes S in the form of a stable compound in the mother phase, improves hot workability, and has a deoxidizing effect. Further, Mg has an effect of improving the strength, the spring limit value, and the heat resistance even in a trace amount. If the Mg content is less than 0.0001%, the above effect is not sufficient. On the other hand, if the content exceeds 0.005%, it becomes a base point of a crack at the time of bending, propagates a crack and deteriorates formability. Therefore, the Mg content is 0.0001% to 0.00%.
5%.

(Zn) In the alloy of the present invention, Zn is an element effective for improving the migration resistance and the weather resistance of the solder and for suppressing the occurrence of whiskers in the Sn plating material. Z
If the n content is less than 0.01%, the effect is small, and Zn
If the content exceeds 5%, the electrical conductivity is reduced and stress corrosion cracking is liable to occur. Therefore, the Zn content is 0.0
1 to 5%. (Pb) Pb improves punching workability (reducing burrs,
This has the effect of reducing mold wear. When the content of Pb is less than 0.0005%, the above effect is not obtained. On the other hand, if the content of Pb exceeds 0.005%, grain boundary cracks occur during hot working, and cracks occur in the ingot. For this reason, the Pb content must be 0.005% or less. Therefore, the content of Pb is 0.00
It is set to be from 0.05 to 0.005%.

(S) In the alloy of the present invention, S exists in the form of a simple substance or a low-melting intermetallic compound or a complex oxide at a crystal grain boundary, so that the punching workability is improved (burr reduction, shearing work). Performance) and the effect of reducing mold wear. If the S content is less than 0.0003%, the above effect is not obtained. On the other hand, when the content of S exceeds 0.003%, S or the sulfide present at the grain boundaries during hot working is melted to cause grain boundary cracking, cracks are generated in the ingot, and the product yield is reduced. descend. Therefore, the S content is 0.003.
%. Therefore, the content of S is 0.1.
0003 to 0.003%. (C) In the alloy of the present invention, C has an effect of improving the deoxidizing action of the molten metal and the punching workability, particularly the shearing workability. However, when the content exceeds 0.0040%, the hot workability is deteriorated. In addition, C can be contained in the molten metal by bringing the charcoal, C particles, and the like that coat the surface of the molten metal into contact with the molten metal during melting and casting. According to this method, C can usually be contained at about 0.0001 to 0.001%.

(O, H) The alloy of the present invention can be obtained by coating the surface of the molten metal with charcoal, C particles, an appropriate flux or the like without using a vacuum furnace, using an ordinary coreless furnace or a grooved furnace. Can be melt cast in the atmosphere. However,
In the melting and casting process in the air, the raw material, the coating material on the surface of the molten metal, moisture or oxide attached to or contained in the furnace material, water vapor, oxygen, carbon dioxide, hydrogen, etc. existing in the atmosphere are mixed with the molten metal. It is inevitable that the molten metal will react and contain O and H. Particularly, once H is contained, it is difficult to effectively remove it. Therefore, it is necessary to pay attention to the melting casting atmosphere, the raw materials used, the drying of the molten metal coating material, and the like so as not to contain more than a predetermined amount. In the copper alloy of the present invention, if the H content exceeds 0.0002%, cracks during hot rolling, swelling during annealing, plating swelling and the like are generated, and the yield is reduced. There must be. A more desirable H content is 0.0001% or less, and still more preferably 0.00007% or less.

In the copper alloy of the present invention, if the O content exceeds 0.004%, an oxide is easily formed in the melting casting step, hot rolling and annealing step, and this oxide causes The ductility tends to decrease. Further, the plating properties of Ag, Sn, solder and the like are reduced by the oxide and the solid solution oxygen. Therefore, the O content must be 0.004% or less. Desirable O content is 0.003
%, More preferably 0.002% or less. Although H and O are usually contained together, the H content: app
When the content of m and O is bppm, the value of a × b is 40.
Exceeds H in a heating step such as hot rolling or annealing.
And O react with each other to form water vapor, which causes cracks, swelling, etc., so that the H content (ppm) × O content (p
pm) is desirably 40 or less. The value is more preferably 30 or less, more preferably 20 or less.

(Other selected elements) Ca, Be, Al,
Fe, Si, Ti, V, Cr, Co, Zr, Nb, M
Since o, In, Hf, Ta, B, Ag, and P are all effective in improving heat resistance, a total amount of up to 0.1% may be added or contained as an impurity. One of these elements
If the seed or two or more kinds are contained in a total amount of more than 0.1%, a coarse oxide is formed at the time of melting casting, hot rolling or working heat treatment, and coarse crystals are generated. In addition, the hot workability is reduced, and even if it is a product, the plating property and the bending workability are reduced. Therefore, the content of one or more of these selected elements is set to 0.1% or less in total. However, since P among the above-mentioned elements tends to lower the hot workability of the copper alloy of the present invention, the content of P is 0.1%.
Desirably, it is not more than 02%. In addition, Bi, As,
Even a small amount of low melting point elements such as Sb and Se segregate at the grain boundaries of the copper alloy of the present invention and reduce hot workability. Therefore, the total content of these elements should be restricted to 0.002% or less. Is desirable.

(Grain Size and Aspect Ratio) In order to achieve the desired strength and bendability in the copper alloy of the present invention, JIS-H0501 is applied to the rolled surface of the plate or strip.
It is desirable that the average crystal grain size a in the width direction of the sheet measured by the cutting method specified in the above is 5 to 20 μm. If the average crystal grain size a is smaller than 5 μm, the bending workability decreases,
Cracks are easily formed in the bent portion. On the other hand, when the average crystal grain size a exceeds 20 μm, the crystal grains are coarse, the strength is apt to be insufficient, and the surface of the bent portion is apt to be rough.
In addition, when the average crystal grain size b measured on the same plane parallel to the rolling direction is out of the range calculated by the aspect ratio described later, similarly, deterioration in bending workability or insufficient strength and rough surface of the bent portion occur. It's easy to do. Further, the present inventors have found that the aspect ratio (b / a) affects strength and bending workability. That is, even if the average crystal grain size a is within the above range, if the aspect ratio (b / a) is less than 2.5, the recrystallized grains are contained in a large amount in the structure, resulting in insufficient strength. On the other hand, when it exceeds 10, the bending workability decreases because a large amount of the rolled structure remains. Therefore, the aspect ratio (b /
a) is desirably 2.5 to 10.

(Proof Strength / Tensile Strength) In the copper alloy of the present invention, the ratio of the proof strength to the tensile strength is determined by the punching workability (burr amount,
It affects the punching cross-sectional ratio (shear surface / fracture surface) that affects the dripping amount. The closer the punching cross section ratio is to the shear plane / fraction surface = 1, the better. When the ratio of proof stress to tensile strength (proof stress / tensile strength) is 0.9 or more, the shear surface / fracture surface becomes almost 1 and the punching workability is improved. Therefore,
The ratio of proof stress / tensile strength is desirably 0.9 or more.

(Manufacturing process) The copper alloy of the present invention has improved strength and bending workability due to spinodal decomposition. Focusing on this point, the manufacturing method of the present invention focuses on strength, spring limit,
It achieves maximization of ductility, bending workability, etc., and generally comprises the following steps.・ Vertical continuous or semi-continuous casting → hot rolling → cold rolling → annealing → cold rolling → annealing → cold rolling → annealing, and tension leveling (straightening).・ Horizontal casting → homogenized annealing → cold rolling → annealing → cold rolling → annealing → cold rolling → annealing, and tension leveling (straightening).

Taking the case of manufacturing by hot rolling as an example,
Each step will be described below. In hot rolling, the ingot is 8
It is desirable to carry out after holding for about 30 minutes to 4 hours after reaching 00 to 950 ° C. After the completion of the hot rolling, it is desirable to rapidly cool to a temperature of 300 ° C. or less at a rate of 10 ° C./sec or more. After cold-rolling the hot-rolled material, the first annealing is performed (annealing in the above step). The purpose of the first annealing is to make the structure work hardened by cold rough rolling into a recrystallized structure, and it is desirable that spinodal decomposition does not occur. Therefore, it is desirable to use a continuous annealing furnace capable of rapid heating and rapid cooling, and the heating can achieve the purpose in a short time at a high temperature. For example, the temperature rising rate to the predetermined temperature and the temperature decreasing rate from the predetermined temperature may be 10 ° C./sec or more, and the holding time may be about 1 to 120 seconds after the material to be heated reaches the predetermined temperature of 600 to 850 ° C.

After the first annealing, cold rolling (working rate is selected from about 10 to 90%) is performed, and a second annealing (annealing in the above step) is performed. The purpose of the second annealing is to partially recover the dislocation structure introduced by the cold rolling, and if a complete recrystallized structure is obtained by this annealing, the copper alloy of the present invention aims at high strength and high spring strength. Limit value and high ductility characteristics cannot be obtained. Therefore, in the second annealing, it is desirable to have a structure in which recrystallization does not occur or a structure in which a reprocessed structure and a processed structure are mixed. In order to obtain such a structure, it is desirable to use a continuous annealing furnace that can be heated for a short time in a medium-high temperature range. As for the heating condition of the material, for example, the material to be heated is 350 to 650 ° C.
Is maintained for about 1 to 180 seconds after the temperature has reached, and the rate of temperature rise to the predetermined temperature and the rate of temperature decrease from the predetermined temperature are desirably 10 ° C./sec or more.

After the second annealing, cold rolling (working rate is selected from about 10 to 60%) is performed, and a third annealing (annealing in the above step) is performed. The purpose of the third anneal is to cause spinodal decomposition to improve mechanical properties such as strength, spring limit, and elongation. Since diffusion of the solute element is indispensable for the progress of spinodal decomposition, a batch furnace such as a bell furnace capable of heating for a long time may be used for this annealing. The heating conditions at this time are: 0.5 to 1 after the material to be heated reaches 300 to 550 ° C.
The temperature may be maintained for about 0 hours, and there is no particular limitation on the temperature raising and lowering rates. It should be noted that the copper alloy of the present invention manufactured by the above manufacturing process may be further subjected to strain correction by applying a tension leveler or the like. Although the manufacturing method of the present invention includes three annealing steps, two of which can be annealed by a continuous annealing furnace, the time required for manufacturing is longer than that of the conventional manufacturing method of performing batch annealing. There is no.

[0020]

EXAMPLES The characteristics of the examples of the present alloy will be described below in comparison with comparative examples. Example 1 demonstrates the feasibility of manufacturing a sheet material, Example 2 demonstrates the effect of the added element, and Example 3 verifies the effect of the heat treatment conditions. (Example 1) A copper alloy having a composition shown in Table 1 was melted in an air atmosphere under a charcoal coating in an electric furnace. Melted ingot (thickness 60
mm, width 70mm, length 200mm) from 850 to 900
After the temperature reached 1 ° C., it was kept for 1 hour and then hot-rolled to a thickness of 15 mm. During and after hot rolling, the occurrence of cracks was visually determined. Table 1 shows the results.

[0021]

[Table 1]

No. 1 within the composition range of the present invention. All of Nos. 1 to 6 had good hot ductility, and no cracks occurred in the hot-rolled material. On the other hand, No. In No. 7, the Ni content was excessive, and cracks occurred during hot rolling. No. 8 has a Sn content of N
o. No. 9 has a Pb content of No. 9; 10 is the content of S,
No. No. 11 has a C content of No. 11; No. 12 has an H content of No. Sample No. 13 had an excessive P content, so cracks occurred during hot rolling, and hot rolling was stopped halfway. These were not subjected to a subsequent thermomechanical treatment.

Example 2 A copper alloy having the composition shown in Table 2 was melted in the air under a charcoal coating using a kryptor furnace. In Table 2, Pb, S, H, and C were all within the claims, so that a good hot-rolled material was easily obtained (the hot rolling conditions were the same as in Example 1). Alloy 1 of the present invention produced in Example 1
6 and the alloys 14 to 23 of the comparative example of the present example, the hot-rolled material (thickness: 15 mm) was subjected to the thermomechanical treatment under the conditions described in the item of the manufacturing process in the column of the embodiment of the present invention. Was performed to produce a 0.25 mm plate material. In addition,
In the first and second heat treatments, a salt bath furnace and a nitrite furnace were used to simulate the thermal history of continuous annealing.

[0024]

[Table 2]

Various test pieces were processed from the plate material thus produced, and the characteristics were evaluated in the following manner. The results are shown in Tables 3 and 4. (Mechanical strength) The proof stress and elongation were measured using JIS No. 5 test pieces (n = 2) with the longitudinal direction of the test pieces parallel to the rolling direction. (Spring Limit) Akashi Spring Limit Tester (MODE
L: APT) by a moment equation test.
The test direction of the material was parallel to the rolling direction (LD). (Punching workability) The required number of strips having a width of 30 mm and a length of 2 m were processed from the above-mentioned plate material, and the width was 3 mm using a punching press.
Clearance of 20mm length lead: 100 at 5%
The burring height and droop width of the material after the shot punching and the lead were measured every 10 shots, and their average values were calculated.

(Fatigue Characteristics) Fatigue characteristics were measured using a thin plate fatigue tester manufactured by Akashi Co., Ltd. on a test piece having a width of 10 mm and a maximum bending stress of 300 N / m at a cycle of 60 Hz.
m ² , double swing, swing width: a repetitive stress of 2.5 mm was applied, and the number of breaks was measured. (Solder weather resistance) MIL-STD-202F METH
After soldering based on OD 208D,
1m after 150 ℃ ・ 1000Hr in air at n = 3
After 180 ° bending back at mφ, the presence or absence of peeling of the solder was visually confirmed.

(Migration resistance) A test piece having a width of 3.0 mm and a length of 80 mm was sampled from the above plate material.
This test piece was set as a set of two pieces and tested at n = 4. FIGS. 1 and 2 show test devices for measuring leakage current using the above-mentioned test pieces, wherein 2a and 2b are test pieces and 3 is 1 mm thick A
BS resin, 3a are holes formed in the ABS resin, and 4 is a holding plate for the ABS resin 3. Reference numeral 5 denotes a clip having an insulating coating applied to the surface to press and fix the holding plate 4, reference numeral 6 denotes a battery, and reference numeral 7 denotes an electric wire. The test piece 2a, 2b has an electric wire 6 connected to an end. A dry test of applying a DC current of 14 V from the battery 6 to the two test pieces 2a and 2b shown in FIGS. 1 and 2 and immersing the test pieces in tap water for 5 minutes, followed by drying for 10 minutes, was performed 50 times. The maximum leakage current during that time was measured with a high-sensitivity recorder (not shown).

(Bending workability) B type bending jig specified in CESM0002 metal material W bending test, width: 10 m
m, length: Insert the test material processed to 35 mm, and use a universal testing machine RH-30 manufactured by Shimadzu Corporation to load R with a load of 1 t.
After performing W bending at / t = 0, the 90 ° bent portion was further bent tightly with a load of 1 t, and the presence or absence of cracks in the bent portion was determined (n = 2). (Stress corrosion cracking resistance) 0.25mmt x 1
A 2.7 mmw × 150 mm test piece (n = 4) was cut out and subjected to a stress corrosion cracking test by the method of Thompson (Mate).
realsResearch & Standards
(1961) 1081). That is,
After the test piece was formed into a loop shape as shown in FIG.
, And exposed to a desiccator filled with saturated steam at a temperature of 40 ° C., and the time until the test piece fractured was measured.

(Heat Resistance) A JIS No. 5 test piece with the longitudinal direction parallel to the rolling direction was heated at a temperature of 400 to 700 ° C. for 5 minutes, and then subjected to a tensile test to determine the relationship between heating temperature and tensile strength. A graph was obtained, and a temperature at which the tensile strength was 80% of the test piece not heated was obtained from the graph. Good heat resistance for test pieces with a temperature of 550 ° C. or higher.
A test piece at a temperature lower than 50 ° C. was classified as heat-resistant deterioration. (Whisker resistance) Approximately 400
After applying a compressive stress of N / mm ² and maintaining the same at room temperature for 3 months, the occurrence of whiskers on the compressed surface was observed with a stereoscopic microscope.

[0030]

[Table 3]

[0031]

[Table 4]

No. Nos. 1 to 6 have compositions, average grain size a in the sheet width direction, and aspect ratio b / a within the range of the present invention, and have good proof stress, spring limit value, close bending workability, and maximum leakage in migration resistance. The current value is kept low, solder weather resistance, stress corrosion cracking resistance is good, and punching workability is excellent. On the other hand, No.
In the case of No. 14, the Ni content is insufficient, so that the yield strength and the spring limit value are low, and the fatigue properties are also inferior. No. In No. 15, the Sn content is insufficient, so that the yield strength and the spring limit value are low, and the fatigue characteristics are also poor. No. No. 16 is inferior in punching workability due to insufficient content of Pb and S. No. No. 17 is inferior in elongation properties due to an excessive O content, and cracks occur in close bending. No. No. 18 is inferior in heat resistance due to insufficient Mn content. No. In No. 19, since the Mn content is excessive, peeling occurs due to solder weather resistance. No.
20 has insufficient Mg content, so that sufficient proof stress and spring limit values cannot be obtained, and heat resistance is also poor. No. 2
No. 1 is inferior in elongation properties due to an excessive content of Mg, and cracks occur in close bending. No. In No. 22, the Zn content was insufficient, so that peeling occurred due to solder weather resistance, migration resistance was poor, and whiskers were generated. No. Sample No. 23 is inferior in stress corrosion cracking resistance due to excessive Zn content.

(Embodiment 3) For the hot-rolled material (15 mm thick) having the composition of No. 2, cold rolling → annealing →
Table 5 in the process of cold rolling → annealing → cold rolling → annealing
Were manufactured (thickness: 0.25 mm), and the material properties of these plate materials were evaluated. Table 5 shows the results.
Shown in In addition, No. In 2-1 to 2-8, cold rolling: 90% or more, annealing: 650 to 800 ° C. × 5
30 seconds, cold rolling: 30-50%, annealing: 400-
650 ° C. × 10 to 120 seconds, cold rolling: 10 to 50
%, Annealing: working heat treatment conditions of 400 to 550 ° C. × 0.5 to 5 hours. On the other hand, No. In 2-9 to 2-18, in the steps after the annealing, the working heat treatment was performed in a range outside the conditions described in the item of the manufacturing process in the column of the embodiment of the invention. Comparative Example 2-19 is a conventional process, in which cold rolling: 90% or more, annealing: 600 ° C. × 1.
Working temperature, cold rolling: 60%, annealing: 400 ° C. × 1 hour, cold rolling: 37.5%, annealing: 400 ° C. × 2 hours.

[0034]

[Table 5]

No. 5 in Table 5. In 2-1 to 2-8, the average crystal grain size a in the plate width direction and the aspect ratio b / a are within specified ranges, the proof stress, tensile strength, spring limit value are high, and the close-contact bending workability is high. It is good, and has the opposite properties of strength and bending workability. Furthermore, it has excellent fatigue characteristics. On the other hand, No. 2-9, the first annealing temperature was too low, the average crystal grain size was small, the tensile strength, the proof stress, and the spring limit were low, and the fatigue properties and bending workability were poor. N
o. 2-10 is the first annealing condition in which the temperature was too high, the crystal grains became coarse and the aspect ratio was small,
Low tensile strength, proof stress and spring limit value, and poor fatigue properties. No. No. 2-11 shows that the working ratio of the cold rolling after the first annealing was too small, and the proof stress / tensile strength ratio and the aspect ratio (b / a) of the crystal grain size were low. The proof stress and the spring limit value are low, and the punching workability is inferior. N
o. In No. 2-12, the working ratio of the cold rolling after the first annealing was too large, and the crystal grain size a was small, the aspect ratio (b / a) was large, and the bending workability was reduced.

No. In No. 2-13, the second annealing temperature was too low, and the grain size could not be measured because of only the rolled structure, and the bending workability was poor. No. No. 2-14, in which the second annealing temperature was too high, the crystal grains were coarsened, the aspect ratio (b / a) was low, and the tensile strength, proof stress, and spring limit value were low. No. No. 2-15 shows that the working ratio of the cold rolling after the second annealing was too small, and the proof stress / tensile strength ratio and the crystal grain size aspect ratio (b / a) were low. The proof stress and the spring limit value are low, and the punching workability and fatigue properties are also deteriorated. No. In No. 2-16, the working ratio of the cold rolling after the second annealing was too large, and the rolled structure occupied the majority, and the bending workability and fatigue properties were poor. No. In No. 2-17, the third annealing temperature was too low, spinodal decomposition did not sufficiently occur, the spring limit was low, and the fatigue properties and bending workability were poor. No. 2
-18 is the third annealing temperature that was too high, resulting in a recrystallized structure, a low proof stress / tensile strength ratio and a low crystal grain size aspect ratio (b / a), and a high tensile strength, proof stress, and The spring limit value is low, and the punching workability and fatigue characteristics are also poor. N
o. In each of the heat treatment conditions 2-19, recrystallization and spinodal decomposition were caused, so that the aspect ratio was low, and the tensile strength, proof stress, and spring limit value were low.

[0037]

As described above, the copper alloy according to the present invention is excellent in mechanical properties and fatigue properties, and is also excellent in bending workability.
It has extremely excellent quality as a high-grade spring material used for personal computers and the like.

[Brief description of the drawings]

FIG. 1 is a plan view of a test device for measuring a leakage current.

FIG. 2 is a sectional view of the same.

FIG. 3 shows D.E. for evaluating stress corrosion cracking resistance. H.
It is a loop-shaped test piece by the Thompson method.

[Explanation of symbols]

 2a, 2b test piece 3 ABS resin

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Claims (5)

[Claims] 1. Ni: 8.5 to 10.5% by mass (hereinafter, mass% is simply referred to as%), Sn: 1.8 to 2.2% by mass.
8%, Mn: 0.005 to 0.05%, Mg: 0.00
01 to 0.005%, Zn: 0.01 to 5%, Pb:
0.0005-0.005%, S: 0.0003-0.
003%, C: 0.004% or less, H:
A high-strength copper alloy characterized by being restricted to 0.0002% or less and O: 0.004% or less, with the balance being Cu and unavoidable impurities. 2. It is made of the copper alloy according to claim 1,
On the rolled surface of the sheet or strip, the average crystal grain size a measured in the sheet width direction is 5 to 20 μm, and the average crystal grain size measured in a direction parallel to the rolling direction is b. Is a high-strength copper alloy plate or strip. 3. It is made of the copper alloy according to claim 1,
A high-strength copper alloy plate or strip having a value of proof stress (σ0.2) / tensile strength (σB) of 0.9 or more. 4. The copper alloy according to claim 1,
Short-time annealing with recrystallization in the middle of cold rolling, further cold rolling, then short-time annealing that does not completely recrystallize, further cold rolling, then annealing, spinodal decomposition The method for producing a high-strength copper alloy sheet or strip according to claim 2 or 3, wherein 5. The method for producing a high-strength copper alloy sheet or strip according to claim 4, wherein the tension leveling is continuously performed.