JP2001032029A - Copper alloy excellent in stress relaxation resistance, and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a copper alloy material excellent in stress relaxation resistance and equivalent or superior to phosphor bronze in balance between tensile strength and elongation, peeling of Sn plating, whisker formation in Sn plating layer, stress corrosion cracking sensitivity, etc. SOLUTION: The copper alloy material has a composition consisting of 3-<4% Sn, 0.5-1.0% Ni, 0.05-5.0% Zn, and the balance copper with inevitable impurities, and further, the total content of substances unentered into solid solution, such as precipitates, is regulated to <=0.02%. This material can be manufactured by carrying out, in the course of cold rolling, heat treatment consisting of holding at 550-700 deg.C for 5 sec to 5 min and successive cooling at >=5 deg.C/sec cooling rate down to ordinary temperature, performing cold rolling to the desired size, and then subjecting the sheet to stabilizing annealing at 325 to 450 deg.C for 5 sec to 180 min.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a spring, a switch, a connector, a diaphragm, a socket, and the like for electric and electronic equipment.
Bellows, fuse clips, sliding pieces, bearings, bushes,
Automotive seat belt springs, washers, etc. (above, processed from plates or strips), bourdon tubes, flexible metal hoses, hose-type bellows, sleeve bearings, etc. (above, processed from tubes), coil springs, etc. (wires) -It is a copper alloy that requires stress relaxation resistance and is used for applications (processed from a rod).

[0002]

2. Description of the Related Art Phosphor bronze in the form of plates, strips, pipes, and wires and rods is mainly used for bourdon tubes, coil springs, etc. for springs, switches, connectors, etc. for electric and electronic equipment for consumer and industrial use. It has been. In recent years, for example, connectors for electronic and electrical devices have become denser, smaller, thinner, with smaller and lighter devices.
Furthermore, the narrow pitch has been advanced, and higher reliability has been required.

[0003] Phosphor bronze is excellent in strength, but has a problem that it is deformed (insufficient in stress relaxation resistance) when it is maintained at a temperature exceeding 140 ° C. in a state where stress is applied. In addition, when tin or gold plating is performed on phosphor bronze, it is common practice to perform Ni base plating.
If the tin plating is performed directly without the Ni base plating, the tin is easily peeled off, copper oxide is formed on the surface of the tin layer and turns black, the contact resistance becomes large, and the solder becomes hard to wet,
There is a problem that tin whiskers are easily generated. In addition, when the pitch between the terminals of the connector is reduced due to the miniaturization of the connector, when moisture is present, an electrical short circuit is likely to occur due to migration. Since phosphor bronze is composed of copper and tin, there is also a problem that migration is likely to occur in bare materials and tin-plated materials, and it is difficult to reduce the pitch.

On the other hand, Japanese Patent Application Laid-Open No. 61-127840 discloses Sn of more than 2% to 10%, P of 0.001% to 0.4%, and Zn of 0.05% to 5%. , And one or two or more of Ni, Co, and Cr
A high-strength, high-conductivity copper alloy containing about 1% to about 1%, with the balance being Cu and inevitable impurities. According to the examples, the steel sheet was annealed at 500 ° C. for 1 hour at 1.0 mmt during cold rolling. However, since one or more kinds of Ni, Co, and Cr are contained, Ni, Precipitation of Co, Cr and P compounds occurs. That is, in the case of the alloy of the present invention, the tensile strength, heat resistance and conductivity of phosphor bronze are improved by forming phosphides of Ni, Co and Cr. JP-A-63-38546 also discloses that a compound of P and Ni precipitates for an alloy similar to the above.

[0005] In addition, Japanese Patent Application Laid-Open Publication No.
n: 2.5 to 9%, P: 0.03 to 0.35%, Ni:
A copper alloy for electric / electronic parts consisting of 0.1 to 1.0%, Zn: 1.0 to 5.0% and the balance essentially consisting of Cu is described, but P is essential and the constituent elements Phosphorus with Ni is generated. In this alloy, the test temperature of the stress relaxation rate was 120 ° C., and as of 1999, it was 140 ° C.
There has been a demand for excellent stress relaxation properties at temperatures exceeding ℃, and it is difficult for such alloys to respond.

As described above, in a connector for electric and electronic equipment using phosphor bronze, tensile strength / elongation balance, peeling of Sn plating, generation of whiskers of Sn plating layer, 140
There are many problems such as stress relaxation at a temperature exceeding ° C., and furthermore, the metal price due to the high Sn content, and the copper alloy materials proposed so far cannot solve all of them. Further, with respect to the susceptibility to stress corrosion cracking, no material exceeding phosphor bronze appears.

[0007]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an excellent stress relaxation property especially at a temperature exceeding 140 ° C., a tensile strength / elongation balance, peeling of Sn plating, and whisker of Sn plating layer. Another object of the present invention is to provide a copper alloy material which is equivalent to or superior to phosphor bronze with respect to the formation of copper, metal price, and susceptibility to stress corrosion cracking.

[0008]

DISCLOSURE OF THE INVENTION The copper alloy according to the present invention comprises:
The basic composition is Cu-Sn-Ni-Zn, Sn: 3% or more and less than 4%, Ni: 0.5% or more and 1.0% or less, Zn:
It contains not less than 0.05% and not more than 5.0%, with the balance being copper and unavoidable impurities. When the copper alloy according to the present invention contains a deoxidizing agent, one or more elements selected from P, B, Mg, and Ca are each P: 0.001% or more and less than 0.03%. , B: 0.0001% to 0.02%, Mg: 0.0001% to 0.05%, Ca:
0.0001% or more and 0.01% or less, 0.000 in total amount
It is regulated to be in the range of 1% or more and 0.1% or less.

As inevitable impurities in the above copper alloy,
Ag, which is inevitable to be mixed from raw materials (Cu
Pb, Fe, Si, Mn, S and O and H which are unavoidable gas bodies at the time of adjusting the molten metal were changed to Ag: 0.1% or less, Pb:
0.01% or less, Fe: 0.05% or less, Si0.05
%, Mn: 0.1% or less, and the above elements in a total amount of 0.3% or less, S: 20 ppm or less, O: 30 ppm or less, and H: 2 ppm or less. Further, the above copper alloy is composed of Be, Al, Ti, Cr, Co, Zr, Sb and Ib.
One or more elements selected from the group of n elements can be contained in a total amount of 0.1% or less.

Incidentally, the copper alloys disclosed in the above-mentioned documents all have a structure in which a phosphide such as Ni is precipitated in a mother phase, so that there is a limit in improving the stress relaxation rate. According to the study of the present inventor, it has been found that it is more advantageous to utilize solid solution or spinodal decomposition rather than precipitation strengthening in order to meet the recent demand for higher stress relaxation properties. In the copper alloy according to the present invention, an unsolid solution such as a precipitate may be contained depending on the composition and the production process. However, when the content exceeds 0.02%, the mechanism of solid solution strengthening or strengthening by spinodal decomposition is not achieved. Since it is lost, the content is set to 0.02% or less. The average crystal grain size is desirably regulated to 1 to 15 μm from the viewpoint of bending workability. Further, in the method for producing a copper alloy according to the present invention, the copper alloy is kept at a temperature in the range of 550 to 700 ° C. for 5 seconds or more and 5 minutes during cold working, and then cooled to room temperature at a cooling rate of 5 ° C./second or more. It is characterized by performing heat treatment, then cold working to a target size, and then performing stabilization annealing in a temperature range of 325 to 450 ° C. for 5 seconds to 180 minutes.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Sn of 3% or more and less than 4% and Ni of 0.5% or more and 1.0% or less are co-added to Cu. For example, after hot working and cold working, the above heat treatment is performed. , Followed by finish cold working and stabilized annealing
A copper alloy having a tensile strength equivalent to that of phosphor bronze containing% Sn can be adjusted, and this copper alloy has a stress relaxation rate of 30% or less even when the copper alloy is held at 150 ° C. for 1000 hours with a stress applied. Small and difficult to deform. Here, if Sn contained in Cu is 3% or more and less than 4% and Ni is less than 0.5%, it becomes difficult to obtain the target tensile strength / elongation balance and good stress relaxation properties, and Ni becomes 1%. %, The contribution to improving the balance between strength and elongation is small, and the electrical conductivity is reduced. Further, Ni contained in Cu is 0.5% or more and 1.0% or more.
%, Sn is less than 3%, it is difficult to obtain a balance between tensile strength and elongation.
The elongation balance is improved, but the conductivity is reduced. The Sn + Ni content of this copper alloy is less than 5%, and the standard JIS-H3110-C519 for 6% phosphor bronze is used.
Lower limit 5.5% of specification 5.5-7.0% of Sn content of No. 1
Value is lower than that of C5
It is cheaper and more economical than 191.

[0012] The copper alloy having the above-mentioned chemical composition contains 0.05% of Zn.
% To 5% or less, there is no need to perform Ni underplating unlike phosphor bronze,
It is possible to perform tin plating after performing a Cu base plating of the following thickness (flash), peeling of the Sn layer, blackening due to heating of the Sn surface, and whisker formation on the electric Sn plating layer. Generation and the like are suppressed. Further, when Zn is contained in the above-described range, migration is suppressed. When the Zn content is less than 0.05%, the above effects are reduced. When the Zn content is more than 5%, stress corrosion cracking peculiar to the copper alloy is liable to occur. Zn also has a deoxidizing effect, and P,
A sound ingot can be formed without adding a deoxidizing agent such as B, Mg, or Ca, or even with a small amount of the deoxidizing agent, but if the content is less than 0.05%. The effect is not enough. Therefore, the Zn content is set to 0.05 to 5%.

P, B, Mg, and Ca have a deoxidizing and desulfurizing (Ca) action of the molten metal. Sn: 3.0% or more and less than 4%, Ni: 0.5% or more.
When a copper alloy containing 0% or less and Zn: 0.05% or more and 5% or less is melted in the air, and when it is necessary to deoxidize the molten metal, P: 0.001% or more and less than 0.03%;
B: 0.0001% or more and 0.02% or less, Mg: 0.0
One or more elements selected from the element group consisting of 001% or more and 0.05% or less and Ca: 0.0001% or more and 0.01% or less are 0.0001% or more and 0.1% or more in total.
Deoxidation may be performed by adding the following. P: 0.001% or more, B: 0.001% or more (CaB
, Mg: 0.0001% or more, Ca:
One or more of 0.0001% or more is 0.0% in total.
If 001% or more does not remain, the deoxidizing effect may not be sufficient, and defects such as entrapment of oxides may occur in the ingot. When adding two or more kinds, it is desirable to add P and other elements. However, P, B, Mg, and Ca are not less than 0.03% and 0.05%, respectively.
If it is added in an amount exceeding 1%, 0.01%, or more than 0.1% in total, the casting surface is deteriorated and the conductivity of the final product is reduced. Further, precipitates such as phosphide of Ni are easily formed. C is mixed from charcoal for preventing oxidation of molten metal and flux at the time of casting, and particularly, Ni, Fe and C are mixed.
When o is contained, C is easily mixed. C is 0.005
%, The hot workability of the ingot deteriorates, so the content should be limited to 0.005% or less.

Ag and Pb are mixed from a Cu raw material, and Fe,
Si and Mn are mixed in from inside and outside the factory. Of these, Ag, when contained in the above-mentioned copper alloy, contributes to an improvement in tensile strength without a decrease in electrical conductivity. However, since the price per unit weight is high, the upper limit is made 0.1%. Pb is inevitably contained from the Cu raw material, but if it is contained too much, the hot workability decreases, so the upper limit is made 0.01%. When Fe, Si and Mn are mixed, the electrical conductivity is reduced with respect to the ratio of improvement in tensile strength, so the upper limits are 0.05%, 0.05% and 0.1%, respectively.
%. From the viewpoints of tensile strength, electrical conductivity and price, one or more of these elements have a total upper limit of 0.3%.

S is mixed in from furnace materials, Cu raw materials, turning chips, charcoal for preventing oxidation, flux during casting, and the like. 2
If the content exceeds 0 ppm, cracks occur during hot working of the ingot. Also, when dissolved in the atmosphere, O and H are absorbed in the molten metal, but under charcoal coating, O contains a predetermined amount of P,
By adding B, Mg and Ca, H can be removed by blowing Ar or N ₂ gas after deoxidation. O: 30 ppm,
H: If more than 2 ppm, the obtained ingot becomes unsound. The smaller these are, the more the ingot becomes sound. Further, Be, Al, Ti, Co,
One or two selected from the group consisting of Zr, Sb and In
Even if the total amount of the elements is 0.1% or less, the mechanical properties, stress relaxation properties, tin adhesion, whisker resistance and conductivity of tin are not impaired.

In the above-mentioned copper alloy, when a precipitate and a crystallized substance are present in a final product (a copper alloy plate / strip, a pipe, a wire / rod after completion of the production process) in an amount exceeding 0.02%, one kind of spinodal It is no longer a mechanism for strengthening the use of decomposition, and excellent properties such as tensile strength / elongation balance and stress relaxation properties are lost. In addition, the average crystal grain size after heat treatment by a continuous furnace, salt bath immersion, or the like performed immediately before final stabilization annealing is 1 to 15 μm.
If m is exceeded, that is, if it is less than 1 μm, the bendability decreases, and if it exceeds 15 μm, the grain boundary is weakened, the bendability is reduced, and the roughness of the bent portion becomes severe.

In the copper alloy of the present invention, Ni and Sn
The strength and stress relaxation resistance can be improved by solid solution strengthening or strengthening by a modulation structure by spinodal decomposition. In order to improve the strength by these mechanisms, in the heat treatment performed during the cold working, a supersaturated solid solution in which precipitation and spinodal decomposition are suppressed as much as possible, and after performing the cold working, a manufacturing process of performing the heat treatment is performed. There is a need. Specifically, the copper alloy having the above-described composition is maintained in a temperature range of 550 to 700 ° C. in which Ni and Sn are in a supersaturated solid solution state during cold working for 5 seconds to 5 minutes, and then 5 ° C./second At the above-mentioned cooling rate, it is cooled to room temperature, and further cold-worked at a predetermined area reduction rate. afterwards,
When the stabilized annealing is performed in the temperature range of 325 to 450 ° C. for 5 seconds or more and 180 minutes or less, the elongation is greatly improved in spite of a small decrease in tensile strength after cold working. As a result, the balance between tensile strength and elongation is improved, and the stress relaxation resistance is improved.

Hereinafter, the heat treatment (annealing) conditions during the cold working will be described. When the heat treatment temperature exceeds 700 ° C., the crystal grain size is 15 μm even if the heating time is less than 5 seconds.
Therefore, even if the subsequent cold working and stabilizing annealing are performed under predetermined conditions, the bending workability essential for a connector or the like is reduced. On the other hand, when the heat treatment temperature is lower than 550 ° C., the recrystallized grain size is small even when heating is performed for more than 5 minutes, and the crystal grain size is less than 1 μm even if the subsequent cold working and heat treatment are performed under predetermined conditions. In some cases, bending workability is reduced. Then, spinodal decomposition of Ni and Sn occurs, and when P and B are contained, the amount of phosphide and / or boride such as Ni increases. In the copper alloy of the present invention, a modulated structure (by spinodal decomposition) effective for improving strength and stress relaxation resistance is developed by heating to a temperature range of 325 to 450 ° C. for a predetermined time or more after cold rolling. be able to. On the other hand, 550
In spinodal decomposition which occurs at a relatively high temperature of around 0 ° C. (less than 550 ° C.), not only is it difficult to impart the above-mentioned properties, but even if cold rolling and heat treatment are performed, the modulation structure does not sufficiently develop. Characteristics cannot be obtained.

If the heating time exceeds 5 minutes, the crystal grain size exceeds 15 μm even at a heating temperature of 700 ° C. or less, and the above-mentioned problem of deterioration in bending workability occurs. When the heating temperature is 5
When P and B are contained even at 50 ° C. or higher, the amount of precipitation increases, and the total content of undissolved substances such as precipitates exceeds 0.02%, so that the target specification cannot be obtained. Further Ni and S
Spinodal decomposition of n occurs. On the other hand, when the heating time is less than 5 seconds, the recrystallized grain size formed even when heated at 550 to 700 ° C. is small, and the bending workability is reduced even if the subsequent cold working and heat treatment are performed under predetermined conditions. Would.

The cooling rate from the heating temperature range is 5 ° C. /
If the time is less than seconds, precipitation occurs during cooling, and the total content of undissolved substances such as precipitates exceeds 0.02%, so that desired properties cannot be obtained. In addition, spinodal decomposition of Ni and Sn occurs. For the reasons mentioned above,
As a heat treatment condition during the cold working, the temperature is maintained in a temperature range of 550 to 700 ° C. for 5 seconds or more and within 5 minutes.
It shall be cooled to room temperature at a cooling rate of at least seconds.

After performing the heat treatment, cold working is performed at a predetermined area reduction rate (about 5 to 95%), followed by stabilizing annealing. The conditions for the stabilization annealing will be described below. Stabilization annealing is performed mainly for the purpose of elongation of a cold-worked material, recovery of a spring limit value, and improvement of stress relaxation resistance.
If the heating temperature is lower than 325 ° C., the above-mentioned object cannot be achieved by heating for 5 seconds to 180 minutes. If the heating temperature is higher than 450 ° C., precipitation is likely to occur, and the stress relaxation resistance is rather deteriorated. ° C. If the heating time is less than 5 seconds, the above object cannot be achieved even if the heating is performed at 325 to 450 ° C. On the other hand, if the heating time exceeds 180 minutes, precipitation is likely to occur, and the above-mentioned object cannot be achieved. For the reasons described above, the conditions for stabilizing annealing are 325
Within a temperature range of 450 ° C. to 5 seconds or more and 180 minutes or less.

The heat treatment during the cold working is desirably performed in a continuous heat treatment line in which the atmosphere is non-oxidizing or reducing in order to suppress precipitation during the heat treatment. As the stabilizing annealing, either continuous annealing or batch annealing may be used. After these heat treatments, pickling, polishing and the like can be performed by a usual method. Furthermore, even if the strain is corrected by a tension leveler before the stabilization annealing or the tension annealing is performed instead of the stabilization annealing or after the stabilization annealing, it is possible to produce a copper alloy having excellent stress relaxation resistance of the present invention. is there.

Conventional material of phosphor bronze of 6% Sn C519
1 is a plate thickness of 0.15 to 0.25 mm and a tensile strength of 650.
N / mm ^2, yield strength: 640 N / mm ^2, elongation: 14%,
Bending workability: W bending R = 0, which is good, but the stress relaxation rate is as large as 60% after a lapse of 1000 hours at 150 ° C, and even at 140 ° C, the stress relaxation rate is 30% and 140 ° C.
Is the upper temperature limit. The conductivity of 6% phosphor bronze is 14%.
% IACS is relatively low. On the other hand, in the present invention, stress relaxation rate: 30% or less at 150 ° C., conductivity: 17% IA
It is superior to 6% phosphor bronze at CS or higher, and has the same tensile strength and elongation balance as 6% phosphor bronze (tensile strength x elongation: 9000)
N / mm ² ·% or more), and a copper alloy less expensive than 6% phosphor bronze can be obtained. Further, it is possible to obtain a copper alloy having the same or better properties as the 6% phosphor bronze in the adhesion between solder and Sn plating, the sensitivity to stress corrosion cracking, and the like.

Hereinafter, the present invention will be described specifically with reference to examples. (Example 1) Various component compositions (Nos. 1 to 1) shown in Table 1
The ingot of 5) was melted and cast in a graphite crucible under an atmosphere of charcoal in an electric furnace using electrolytic copper and electric wires as raw materials. The dimensions of the ingot were 50 mm in thickness × 80 mm in width × 190 mm in length.
m. This was heated at 800 ° C. for 30 minutes, quenched in water, and the surface was chamfered to a thickness of 9.8 mm. This sheet material was cold-rolled to a thickness of 0.50 mm without being subjected to annealing in the middle, and was placed in a salt bath at 600 ° C. for 30 minutes.
After holding for 2 seconds, it was quenched in water. Thereafter, the sheet was cold-rolled to a thickness of 0.25 mm, held in a salt bath at 425 ° C. for 30 seconds, and quenched in water to prepare a copper alloy sheet. In addition, the comparative alloy No. 16 6% phosphor bronze C5191 is manufactured by horizontal casting, cold rolling and annealing are repeated after homogenizing treatment to obtain a 0.25 mm thick plate, and the plate material is heated at 350 ° C. in a salt bath at 350 ° C.
The adjustment was carried out by holding for 0 second.

[0025]

[Table 1]

With respect to the above-mentioned copper alloy sheet material, the tensile strength, proof stress, and elongation were measured in the following manner, and the conductivity, stress relaxation rate, stress corrosion cracking resistance, tin adhesion, and the amount of undissolved material were examined. Was. The results are shown in Tables 2 and 3. Tensile strength, proof stress, elongation: Measured with JIS No. 5 test piece. When the longitudinal direction of the sample is parallel to the rolling direction,
Those perpendicular to the rolling direction are indicated by ⊥. Conductivity: Measured in accordance with JIS H0505. Stress relaxation test: 0.25mmt x 10mmw x 80m
ml of the test piece was attached to a cantilever type test jig, and subjected to bending so that the maximum bending stress became 80% of the proof stress at room temperature. Then, the test piece was held in a 150 ° C. oven to check the deformation of the test piece. After a lapse of 1000 hours, the temperature was measured at room temperature, and the ratio to the initial stress was calculated. Those having a stress relaxation rate exceeding 30% were evaluated as x.

Stress corrosion cracking resistance: D, H, Thomp
son (Materials, Res. and Std)
s. 1 (1961), P108-111). Specimen size is 0.25
mmt × 12.7 mmw × 150 mml (n = 5), 28% ammonia water was diluted with an equal volume of distilled water to make 2 l, and this was put into a 5 l desiccator and constrained in a loop in the gas phase. The test piece is put in, held at 35 ° C., and after a lapse of 10 to 30 hours, the loop-like restraint is removed, and the deformation amount of the test piece, that is, the distance between the loop-shaped test piece ends becomes 50% or less of the initial value. The time was measured. Comparative alloy N
o. Those that became 50% or less earlier than 16 were evaluated as x, and those that were late were evaluated as o. Tin adhesion: Electroplating of a 1 μm thick copper alloy material using a tin sulfate bath containing a brightener.
After holding in an oven at 0 ° C. for 1000 hours, the test piece was taken out, bent by 180 ° with a jig having a radius of 1 mmR, returned to the original state, and the state of adhesion of tin at the bent portion was investigated. Those from which tin was peeled were evaluated as x, and those which did not peel were evaluated as o.

Unsolid solution weight: The final product is nitric acid 3: water 1
The precipitate as an insoluble residue was collected with a filter paper (manufactured by Toyo Roshi Kaisha Co., Ltd., GS25), washed with distilled water, dried at 105 ° C. for 1 hour in a thermostat, and then dried at room temperature. 6
The mass after holding for 0 minutes was measured. The mass of the filter paper measured before collection of the precipitate was subtracted to obtain the amount of undissolved material, and the ratio of the obtained amount of undissolved material to the original sample mass was calculated. Most of the unsolid solution is a precipitate, and the size of the precipitate is usually about several tens to several hundreds of angstroms, but most of the precipitate is dissolved and aggregated in a state extracted as a residue. Collected on top of filter paper.

[0029]

[Table 2]

[0030]

[Table 3]

As shown in Tables 2 and 3, the tensile strength, proof stress, and elongation of the alloy of the present invention were as follows. 1 to 9 all have a tensile strength of 620 N / mm ² or more and a proof stress of 570 N / mm.
² or more, elongation of 13% or more, tensile strength x elongation: 9000 N in either or both of the rolling parallel direction and the vertical direction
/ Mm ² ·% or more. The properties of the test pieces in the direction parallel to the rolling direction were the same as those of Comparative Alloy No. No. 16 (C5191), and the characteristics in the direction perpendicular to the rolling direction are No. Better than 16. Regarding the electrical conductivity, the alloy No. 1 of the present invention was used. Each of the plate materials of Nos. 1 to 9 satisfies 17% IACS. 1
Better than 6. Regarding the stress relaxation rate, the alloy N of the present invention was used.
o. The plate materials of Nos. 1 to 9 remain 3 hours even after 1000 hours at 150 ° C.
0% or less, which is good. 11-
13 is 30% because the Ni content is as small as 0.3 or 0.4%.
Is over.

In the evaluation of the stress corrosion cracking resistance, the comparative alloy No. No. 16 cracked in all (n = 5) during the lapse of 14 to 20 hours. 1 to 9 are all N
o. The cracking time is longer than that of 16, and the life is excellent.
In addition, the comparative alloy No. 11 and No. 14 is Zn content 5%
No. Cracking occurred earlier than the time of Comparative Alloy No. 16. In No. 15, Zn is 2%, but P is 0.1%.
No. 05%. Cracks occurred in a shorter time than 16. Regarding the peeling of tin, the alloy No. of the present invention was used. 1-9
No peeling of tin occurs after 1000 hours at 150 ° C., but the comparative alloy No. 10 and No.
No. 16 caused peeling. In addition, the comparative alloy No. 10 is S
No. 28 ppm and O 35 ppm, the ingot has many pinholes. 11 has a hydrogen content of 2.5 pp
m and many. 15 is S at 25 ppm and C at 0.01
%, Small cracks occur in the ears during hot rolling, resulting in poor hot workability.

(Example 2) Two kinds of copper alloys (all of the alloys of the present invention) having the compositions shown in Table 4 were subjected to the same process as in Example 1 for ingot making, hot rolling, solution treatment, and cold rolling. Was performed to obtain a plate material having a thickness of 0.50 mm. This was processed by the processes shown in Tables 5 and 6, and the tensile strength, proof stress, elongation, stress relaxation rate, and the weight of the precipitate were measured as described above, and the crystal grain size and W bending workability were measured as described below. Table 5 shows the results.
And Table 6. Crystal grain size: The average crystal grain size after heat treatment (before final cold rolling) was determined in accordance with the cutting method specified in JIS-H0501. W bending workability: J in the rolling direction or the direction perpendicular to the rolling direction
Using the No. 4 test piece of IS-Z2204, JIS-H31
A W bending test was performed at a bending radius of R = 0 according to 10.

[0034]

[Table 4]

[0035]

[Table 5]

[0036]

[Table 6]

As shown in Table 5, according to the process of the present invention, 6
The sheet material quenched in water after salt bath annealing at 00 ° C for 30 seconds,
Although the crystal grain size is as fine as 5 μm and the W-bending workability is good, as shown in the comparison step, the one annealed in a salt bath at 750 ° C. for 30 seconds has a large crystal grain of 40 μm.
The mechanical properties are also reduced, and the bending workability is also poor. Furthermore, what was annealed in a salt bath at 525 ° C for 60 seconds,
The crystal grain size is small and elongation and bending properties are poor. The amount of unsolid solution generated is also increasing. Further, as shown in Table 6, although the sheet material manufactured according to the process of the present invention had a low stress relaxation rate, as shown in the comparative process, the cooling rate after the intermediate annealing was reduced to 75 ° C./hour. When the amount of the precipitate is 0.03%, the stress relaxation rate becomes a value exceeding 30%, and the mechanical properties are also reduced.

[0038]

The copper alloy according to the present invention is difficult to relieve stress,
Springs for electrical and electronic equipment, switches, connectors, diaphragms, sockets, bellows, fuse clips, sliding pieces,
Suitable for applications such as bearings, bushings, springs for automotive seat belts, washers, etc., this property is also exhibited in tubes or wires / rods. The alloy of the present invention has a basic composition of Sn: 3% to less than 4%, Ni: 0.5% to 1.0%, Zn:
0.05% or more and 5.0% or less;
By short-time annealing at 50 to 700 ° C for 5 seconds to 5 minutes (one time only) and final 325 to 475 ° C for 5 seconds to 180 minutes, phosphorus can be reduced both in composition and processing steps. Since it is cheaper than bronze (C5191) and can be manufactured in a short process, it is very economical.

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Claims (8)

[Claims] 1. Sn: 3% (% by mass, the same applies hereinafter) or more 4
%, Ni: 0.5% or more and 1.0% or less, Zn: 0.1% or less.
Stress relaxation, characterized by containing not less than 0.05% and not more than 5.0%, the balance being copper and inevitable impurities, and having a total content of undissolved substances such as precipitates of not more than 0.02%. Copper alloy with excellent properties. 2. P: 0.001% or more and less than 0.03%,
B: 0.0001% or more and 0.02% or less, Mg: 0.0
One or more elements selected from the element group consisting of 001% or more and 0.05% or less and Ca: 0.0001% or more and 0.01% or less are 0.0001% or more and 0.1% or more in total.
The copper alloy excellent in stress relaxation resistance according to claim 1, comprising: 3. Ag: 0.1% or less, Pb: 0.01%
Fe: 0.05% or less, Si 0.05% or less, M
The stress relaxation resistance characteristic according to claim 1 or 2, wherein one or more elements selected from the element group consisting of n: 0.1% or less are contained in a total amount of 0.3% or less. Excellent copper alloy. 4. The copper alloy excellent in stress relaxation resistance according to claim 1, wherein S: 20 ppm or less, O: 30 ppm or less, and H: 2 ppm or less. 5. Be, Al, Ti, Cr, Co, Zr,
The stress relaxation resistance characteristic according to any one of claims 1 to 4, wherein one or two or more elements selected from the element group of Sb and In are contained in a total amount of 0.1% or less. Excellent copper alloy. 6. The copper alloy excellent in stress relaxation resistance according to claim 1, wherein the copper alloy has an average crystal grain size of 1 to 15 μm. 7. At 150 ° C. under a load of a bending stress corresponding to 80% of the 0.2% proof stress at room temperature,
The copper alloy excellent in stress relaxation resistance according to any one of claims 1 to 6, wherein a stress relaxation rate after holding for 000 hours is 30% or less. 8. The method for producing a copper alloy according to claim 1, wherein the 550 to 70
After maintaining at a temperature range of 0 ° C. for 5 seconds or more and within 5 minutes, performing a heat treatment of cooling to room temperature at a cooling rate of 5 ° C./second or more, and then performing cold working to target dimensions,
A method for producing a copper alloy having excellent stress relaxation resistance, characterized in that stabilized annealing is performed in a temperature range of 0 ° C for 5 seconds to 180 minutes.