JPH07258803A - Production of titanium-copper alloy excellent in bendability and stress relaxation property - Google Patents

Abstract

PURPOSE:To obtain the alloy having high strength, comparable to Cu-Be alloy, by strictly specifying the proportion of Ti in a Cu-Ti alloy and regulating crystalline grain size by applying solution heat treatment prior to each cold rolling performed twice under specific conditions. CONSTITUTION:A copper alloy, having a composition consisting of, by weight, 0.01-4.0% Ti and the balance Cu, is subjected to solution heat treatment at >=800 deg.C for <=240sec under the heat treatment conditions where average crystalline grain size does not exceed 20mum. Then, cold rolling is done at <80% draft. Subsequently, a second solution heat treatment is done at >=800 deg.C for <=240sec under the heat treatment conditions where average crystalline grain size is 1-20mum. Then, a second cold rolling is done at <=50% draft. Further, aging treatment is done at 300-700 deg.C for 1-<15hr. Moreover, 0.05-2.0% Zn and 0.01-3.0%, in total, of one or more elements among Cr, Zr, Fe, Ni, Sn, In, Mn, P, and Si can further be incorporated into the above alloy.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a titanium-copper alloy excellent in bendability and stress relaxation characteristics, and more specifically, it will be used for various electronic parts such as terminals, connectors, relays or switches. The present invention relates to a method for producing a titanium-copper alloy which is used for producing products in all fields in which good bendability is required and high spring properties are required.

[0002]

2. Description of the Related Art Conventionally, for materials that require electrical conductivity and spring properties, such as various terminals, connectors, relays, and switches of electronic equipment, inexpensive "brass" has been used for cost-sensitive applications, and spring characteristics Phosphor bronze was used in applications where is important, or nickel silver is used in applications where spring characteristics and corrosion resistance are important.

However, in recent years, with the trend toward miniaturization and thinning of electronic devices and parts thereof, these materials cannot always be said to have sufficient strength, and therefore beryllium copper (hereinafter referred to as "Cu-Be alloy"). There is an increasing demand for high-grade spring materials having high strength such as titanium) (hereinafter referred to as “Cu-Ti alloy”) and titanium copper (hereinafter referred to as “Cu—Ti alloy”).

Japanese Patent Publication No. 2-49379 discloses Ti:
0.1-3.0%, Si: 0.03-1.5%, Ti /
Cu-T having a composition in which the Si weight ratio is 2 to 4 and in which a Ti-Si based intermetallic compound is dispersed and precipitated in a Cu matrix.
i alloy is hot-rolled into a slab (ingot), complete solid solution of Ti and Si by quenching from hot-rolling finishing temperature, cold-rolling, annealing for precipitating Ti-Si based intermetallic compound, ductility and It is manufactured by sequentially performing tension annealing to improve the bendability.

[0005]

In recent years, electronic devices and their parts are becoming lighter, thinner, shorter, and smaller, so that the requirements for the strength and bendability of materials are becoming strict. C
In the u-Be alloy, in order to meet such a severe bending requirement, strong bending is performed in a solution treatment state,
After that, a method of performing heat treatment to obtain strength is carried out, but in this method, the heat treatment step must be performed by the electronic component manufacturer using the material. Therefore, electronic component manufacturers are increasingly required to provide materials that do not require a heat treatment step after bending, and it is expected that this requirement will further increase as the components become lighter and thinner. Further, although the Cu-Be alloy has high strength, it has a drawback that the price is expensive because beryllium is highly toxic and requires special manufacturing equipment.

The Cu-Ti-Si alloy proposed in Japanese Patent Publication No. 2-49379 mentioned above has a tensile strength of about 54 to 61 k.
g / mm @ 2 and conductivity of about 37-50% IACS. Although good results have been obtained with respect to (folding) bendability, it is not obtained with a material comparable to the Cu-Be alloy.

[0007] Therefore, the present inventors have conducted intensive studies in order to improve the bendability and strength of the Cu-Ti alloy, paying attention to the crystal grain size and the number of times of cold rolling and solution treatment, and as a result, Cu It was revealed that the strength and bendability were improved by adjusting the average crystal grain size of the —Ti alloy to 1 to 20 μm. That is, the present invention provides a method for producing a high-strength copper alloy with improved bendability and strength of the Cu-Ti alloy.

[0008]

The present inventors have found that Cu-T
In order to improve the bendability and strength of the i-alloy, as a result of intensive studies focused on the crystal grain size and the number of times cold rolling and solution treatment were carried out, the Ti content was limited to a certain ratio strictly as an alloy component.
A solution treatment is performed each time prior to the second cold rolling; the first solution treatment is performed after the treatment.
The conditions are such that the average crystal grain size of Cu crystals having i as a solute is adjusted to 20 μm or less; the average crystal grain size by the second solution treatment is adjusted to 1 to 20 μm in a sized state; In order to sufficiently dissolve Ti in Cu while preventing solidification, a solution treatment is performed twice with cold rolling interposed in the middle; In addition to being able to combine various characteristics such as conductivity, bendability, and stress relaxation characteristics at a high level desired for current and future electronic devices in a well-balanced manner, Cu-T
i Add an appropriate amount of Zn to the basic composition, and further add C if necessary.
Further improvement of soldering properties and strength properties is possible by adding r, Fe, Ni, Sn, In, P and / or Si; cold wire drawing, cold forging, etc. instead of cold rolling. It was possible to obtain new knowledge that the processing of can be performed.

The present invention has been completed by embodying the above findings, and Ti: 0.01 to 4.0%
(% Representing the component ratio is "% by weight"), or further Zn: 0.05 to 2.0%, and Cr, Z
1 of r, Fe, Ni, Sn, In, Mn, P and Si
In addition to containing 0.01 to 3.0% in total of at least one species,
Copper alloy with the balance Cu and unavoidable impurities,
(1) First solution treatment performed at a temperature of 800 ° C. or higher for 240 seconds or less under heat treatment conditions in which the average grain size does not exceed 20 μm, and (2) first cold rolling performed at a workability of less than 80%. (3) Second solution treatment performed at a temperature of 800 ° C. or higher for 240 seconds or less under heat treatment conditions in which the average crystal grain size does not exceed 1 to 20 μm, (4) Performed at a working degree of 50% or less Second cold rolling, (5) 300-700
The method is characterized by sequentially performing an aging treatment for 1 hour or more and less than 15 hours at a temperature of ° C.

[0010]

The reasons for limiting the component composition and the production conditions of the present invention will be described in detail below together with their action. Ti : Ti has the effect of causing spinodal decomposition when a Cu-Ti alloy is aged to form a concentration-modulated structure in the base material, thereby ensuring extremely high strength, but its content is If it is less than 0.01%, the desired strengthening cannot be expected. On the other hand, if Ti is contained in excess of 4.0%, precipitation of grain boundary reaction type is likely to occur, resulting in a decrease in strength or deterioration of workability. Therefore, the Ti content is set to 0.01 to 4.0%.

Zn : Zn is expected to have the effect of improving the solder heat release property without lowering the conductivity of the Cu—Ti alloy, so it is added as necessary, but its content is 0.0
If it is less than 5%, the desired effect cannot be obtained, while 2.0
%, The conductivity and stress relaxation characteristics deteriorate, so the Zn content is 0.05-2.0%.
I decided.

Cr, Zr, Fe. Ni, Sn, In, M
n, P and Si : Cr, Zr, Fe, and Ni all suppress grain boundary type precipitation without significantly reducing the conductivity of the Cu-Ti alloy, refine the crystal grain size, and further increase the strength by aging precipitation. And so on. Also, Sn,
In, Mn, P, and Si are mainly Cu-due to solid solution strengthening.
It has the effect of improving the strength of the Ti alloy. Therefore, if necessary, one or more of these elements are added, but if the total content is less than 0.01%, the desired effect due to the above action cannot be obtained, while the total amount is 3.0%.
If the content exceeds the range, the conductivity and workability of the Cu-Ti alloy are significantly deteriorated. For this reason, Cr, Zr, F, which are added singly or in combination of two or more,
The total content of e, Ni, Sn, In, Mn, P and / or Si was set to 0.01 to 3.0%.

Next, the manufacturing process will be described. In the present invention, the solution treatment and the subsequent cold rolling process are performed twice, and then the aging treatment is basically performed. That is, since it is difficult to obtain a grain size controlled structure while securing strength by a general method of performing solution treatment and cold rolling only once, it is possible to sufficiently exhibit the characteristics of the Cu—Ti— (Zn) alloy. It is a process. The manufacturing conditions for explaining the reason for the limitation are set from this viewpoint as well.

Solution Treatment In the present invention, the temperature of the first and second solution treatments is set to 800 ° C. or higher in order to obtain a high-strength material in the subsequent aging treatment by sufficiently dissolving Ti. . That is, when the treatment temperature is lower than 800 ° C., Ti does not form a solid solution depending on the content of Ti, and the high strength characteristic of the age hardening type copper alloy cannot be obtained. The material holding time at a temperature of 800 ° C or higher, that is, the "processing time" is 240
The reason for setting the time within seconds is that coarsening of crystal grains occurs in the processing time of 240 seconds or more.

Corresponding to the Ti amount of the raw material, the crystal grain size before the solution treatment, etc., so that the average crystal grain size is 20 μm or less in the first solution treatment of the two solution treatments. It is necessary to adjust the solution treatment time within 240 seconds. The control of the crystal grain size as described above in the first solution treatment is performed in the second solution treatment in the sized state.
This is to obtain a crystal grain size of μm or less. That is, if the average crystal grain size after the first solution treatment exceeds 20 μm, the solution treatment temperature is lowered and the treatment time is shortened in order to obtain the average crystal grain size of 20 μm or less in the second solution treatment. Even if mixed grains or unrecrystallized parts are generated.

The average crystal grain size after the second solution treatment is set to 1 to 20 μm because the crystal grains have a great influence on bendability and stress relaxation characteristics. When the average crystal grain size is less than 1 μm, when such a microcrystalline material is used as a leaf spring, the stress relaxation characteristic is deteriorated, and when this is used as a leaf spring, the spring pressure is reduced at an early stage. Again 2
If it exceeds 0 μm, the surface is likely to be roughened during bending, and it may be broken if the bending radius is small. The cooling method after the solution treatment is not particularly limited, but it is preferable to perform air cooling or water cooling having a sufficiently high cooling rate so that Ti does not precipitate.

[0017] Since the working ratio of the cold rolling first cold rolling becomes difficult to proceed with the reduction surface of the ingot upon work hardening is remarkably practical operation and 80% or more, between the first cold rolling Is performed at an arbitrary workability of less than 80%. However, 30% or more is preferable. Two
When the cold rolling for the second time is performed at a workability of more than 50%, the texture is significantly developed by rolling, the anisotropy becomes large, and the bendability in the bending axis perpendicular to the rolling direction deteriorates. In addition, it is performed at a working ratio of 50% or less.

Aging treatment Aging treatment is performed to improve strength and conductivity.
Perform at 0-700 ° C. If the aging temperature is less than 300 ° C, the aging process takes time and is not economical, while 700 ° C.
If the content of Ti exceeds the range, Ti will form a solid solution depending on the Ti content, and the strength and conductivity characteristic of the age-hardening type alloy cannot be obtained. Therefore, aging treatment in the temperature range of 300 to 700 ° C. is required. is there. For stable improvement of strength and conductivity, aging treatment at 420 to 480 ° C is recommended for practical use. When the aging time is less than 1 hour, improvement in strength and conductivity due to aging cannot be expected, and when it exceeds 15 hours, strength is significantly reduced due to overaging.
Time aging is necessary.

In the production method of the present invention, the average crystal grain size after solution treatment and the final cold rolling workability are extremely important for obtaining good bendability, and both conditions are defined. Unless the above condition is satisfied, a material having good bendability cannot be obtained. In actual operation, it is natural to adjust the workability, temperature, and time within the above range based on the plate thickness and other specifications determined by the specific application of the Cu-Ti alloy, but the tensile strength is Is about 980 N / mm2 or more, the spring limit value is about 950 N / mm2 or more, and the electric conductivity is 13% IA.
The above conditions are adjusted so that CS or higher can be obtained.

[0021]

EXAMPLES Next, the present invention will be described in more detail with reference to examples showing particularly preferable alloy composition ranges. First, using electrolytic copper or oxygen-free copper as a raw material, copper alloy ingots (thickness: 20 mm) having various compositions shown in Table 1 (Examples) and Table 2 (Comparative Examples) were melted in a high-frequency vacuum melting furnace. Next, each of these ingots was subjected to the first solution treatment (850 ° C. × 0.0458 hours (165 seconds)) in order to adjust the crystal grain size in the table, the first cold rolling 40%, and the second time. Solution treatment (850 ° C. × 0.017 hours (60 seconds)),
The second cold rolling and aging treatment (430 ° C. × 8 hours) were sequentially performed to obtain a 0.30 mm plate.

Then, various test pieces are sampled from the plate material obtained by performing the series of treatments described above, and a material test is conducted to determine the characteristics of the spring material as "strength", "conductivity", and "springiness". , "Bendability" and "stress relaxation characteristics" were evaluated. Among these characteristics, "strength" and "elongation" were measured by a tensile test, and "conductivity" was determined by measuring the conductivity (% IACS). As for the "spring property", the spring limit value (Kb) was measured.

Next, the "bendability" was evaluated by conducting a bending process with a W bending tester and visually observing the bent portion to examine the degree of rough skin and the presence of cracks. In addition, the evaluation results are indicated by ◯: no skin roughness and cracking occurred, X: skin roughness or cracking occurred.

Regarding the "stress relaxation characteristics", one end of a strip-shaped test piece was fixed, and a stress was applied to the other end to apply bending stress. It was evaluated by a method of measuring the strain still remaining even when opened.

Further, the material is 5 μm thick solder (90% S
n-10% Pb) After plating, hold in a high temperature tank at 150 ° C for 1000 hours, take out every 100 hours and perform 90 ° bending reciprocation once to check the start time of solder peeling. , "Solder heat resistance peeling resistance" was investigated and 1
If the peeling did not occur up to 000 hours, the investigation result was "10.
"00 hr" was displayed. The results of these investigations are shown in Table 3 (Examples) and Table 4 (Comparative Examples).

[0026]

[Table 1] Composition A second aging treatment during solution heat treatment under treatment Ti Zn Other Cu and grain size Cold rolling time Impurity (μm) Workability 1st 2nd (%) (hr) 1 3.2 - residual 10 20 40 8 2 2.9 1.2 residual 15 10 45 8 3 2.9 - Sn0.17 remaining 12.5 12.5 40 8 4 3.0 - P 0.21 remaining 12.5 15 50 8 5 3.4 - Note 1 Remaining 10 10 50 8 6 3.1 − Note 2 Remaining 15 10 40 8 7 3.3 − Note 3 Remaining 10 20 50 8 8 2.9 1.7 Note 4 Remaining 10 12.5 40 8 9 3.1 0.6 Note 5 Remaining 15 15 40 8 10 3.1 1.3 Note 6 Remaining 20 15 40 8 11 2.9 1.4 Note 7 Remaining 10 10 40 8 12 3.0 0.8 Note 8 Remaining 15 10 50 8 13 3.0 1.3 Note 9 Remaining 15 12.5 45 8 14 3.2 1.5 Note 10 Remaining 10 12.5 40 8 15 3.0 1.6 Mn0.42 Remaining 12.5 10 40 8 16 2.9 0.8 In Remaining 10 10 45 8 17 2.9 1.2 Si Remaining 10 10 45 8 18 3.2 1.4 Fe Remaining 10 12.5 40 8 19 2.9 1.0 Ni Remaining 15 10 40 8 20 3.1 1.2 Cr Remaining 10 12.5 50 8 21 3.1 0.8 Zr Remaining 15 12.5 45 8

Note 1: In0.32, Si0.07, Fe0.02 Note 2: Sn0.24, Mn0.15, Cr0.05, Zr0.08, Ni0.01 Note 3: Cr0.12, Zr0.15, Fe0.06, Ni0.04 Note 4: In0.30, Mn0.14, P0.13 Note 5: Sn0.10, In0.15, Si0.12, Fe0.13 Note 6: Sn0.12, In0.07, Mn0.21, P0.08, Si0.13 Note 7: P0.06, Si0.04, Cr0.32, Zr0.05, Fe0.12, Ni0.
14 Note 8: Sn0.32, In0.12, Mn0.21, P0.04, Si0.03 Note 9: Cr0.28, Zr0.12, Fe0.02 Note 10: Cr0.43, Zr0.04, Fe0. 21, Ni0.26

[0028]

[Table 2] Composition A second aging treatment during solution heat treatment under treatment Ti Zn Other Cu and grain size Cold rolling time Impurity (μm) Workability 1st 2nd (%) (hr) 22 0.008 - - residual 10 15 40 8 23 0.006 1.5 Note 1 residual 10 20 40 8 24 6.8 - Note 2 residual 10 20 40 8 25 5.4 0.8 Note 3 residual 10 10 45 8 26 2.9 3.7 Note 4 Remaining 15 10 40 8 27 3.1 1.4 Note 5 Remaining 40 Unrecrystallized part 45 8 Yes 28 2.9 1.3 Note 6 Remaining 15 70 40 8 29 3.0 1.5 Note 7 Remaining 12.5 10 85 8 30 3.1 1.5 Note 8 Remaining 10 10 45 20 31 2.9 1.8 Note 9 Remaining 12.5 10 45 0.5 32 3.2 − − Remaining − Mixed grain 40 8 33 3.2 − − Remaining 10 − 40 8 34 3.2 − − Remaining 10 10 0

Note 1: Sn0.17, In0.18, P0.04, Si0.03 Note 2: Sn0.14, P0.12, Cr0.31, Zr0.15, Fe0.08 Note 3: In0.26, P0.02, Zr0.11, Ni0.05 Note 4: Sn0.22, P0.15, Fe0.03, Ni0.06 Note 5: Mn0.22, P0.03, Si0.07, Zr0.14, Fe0. 06, Ni0.
12 Note 6: Sn0.15, In0.07, Mn0.06, Si0.08, Fe0.14 Note 7: P0.08, Si0.18, Cr0.23, Ni0.07 Note 8: Sn0.26, Mn0. 18, Cr0.42, Zr0.ll, Fe0.01 Note 9: In0.21, Mn0.03, Zr0.08, Fe0.14, Ni0.l6 The underline in the table means a value outside the scope of the present invention. To do.

[0030]

[Table 3] Synthetic extension spring Electric bending Stress relaxation Solder heat resistant gold Tensile strength and limit value Conductivity characteristics Peeling time No. (N / mm2) (%) (N / mm2) (% IACS) Performance (%) (hr) 1 990 12.2 974 13.2 ○ 4.7 100 2 982 13.8 960 13.4 ○ 4.6 1000 3 992 12.5 980 13.4 ○ 5.1 100 4 1004 12.3 985 13.0 ○ 4.5 100 5 1015 13.5 997 13.8 ○ 4.7 100 6 1017 13.0 1010 14.4 ○ 4.5 100 7 1013 12.4 1006 15.3 ○ 4.8 100 8 1027 13.7 1017 14.4 ○ 5.0 1000 9 1020 14.5 1008 14.5 ○ 4.3 1000 10 1018 15.7 1009 13.8 ○ 5.2 800 11 1025 13.2 1015 13.3 ○ 5.4 1000 12 1020 15.2 1010 13.6 ○ 4.5 1000 13 1010 12.8 1000 14.7 ○ 5.3 1000 14 1021 14.4 1014 14.1 ○ 4.2 900 15 1015 14.0 1012 14.0 ○ 4.3 800 16 1020 13.7 1000 13.4 ○ 5.0 800 17 1024 14.2 1005 13.0 ○ 5.2 800 18 1010 15.0 997 14.2 ○ 5.2 1000 19 1005 14.7 982 13.8 ○ 4.5 1000 20 1030 12.8 1010 13.6 ○ 4.3 900 21 1017 14.0 998 14.1 ○ 4.2 1000

[0031]

[Table 4] Synthetic extension spring Electric bending Stress relaxation Solder heat resistant gold Tensile strength and limit value Conductivity characteristics Peeling time No. (N / mm2) (%) (N / mm2) (% IACS) Properties (%) (hr) 22 603 22.4 582 15.2 ○ 6.0 100 23 622 21.7 595 15.4 ○ 6.2 1000 24 652 20.8 630 14.3 ○ 5.3 100 25 638 21.5 604 14.6 ○ 5.5 900 26 1012 12.4 992 8.4 ○ 10.4 900 27 874 11.7 850 13.8 × 6.0 1000 28 950 15.4 933 13.7 × 3.7 900 29 1030 5.8 1012 14.2 × 4.8 1000 30 912 16.7 900 14.0 ○ 4.7 1000 31 880 17.1 862 13.2 ○ 4.5 1000 32 877 16.5 848 13.5 × 4.2 100 33 1105 1.2 1088 13.7 × 5.3 100 34 617 23.2 588 14.0 ○ 5.1 100

The following is clear from the results shown in Tables 3 and 4. That is, the alloys 1 to 21 of the present invention are all excellent in strength, bendability, and stress relaxation characteristics, and sufficiently good evaluations can be obtained for other characteristics.

On the other hand, the comparative alloys 22 and 23 are made of Ti.
The content is not sufficient, and the comparative alloys 24 and 25 are inferior in strength because the Ti content exceeds the upper limit. Moreover, since the Zn content of the comparative alloy 26 exceeds the upper limit value, the conductivity and the stress relaxation property are greatly deteriorated. Comparative alloy 27 is an example in which the crystal grain size during the second solution treatment was not successfully created because the crystal grain size during the first solution treatment exceeded the upper limit. Comparative alloy 28 is
The bendability is poor because the crystal grain size during the second solution treatment exceeds the upper limit. Comparative alloy 29 is inferior in bendability because the workability of the second cold rolling exceeds the upper limit value. Comparative alloy 30 had an aging treatment time exceeding the upper limit, and Comparative alloy 31 had a poor aging treatment time and thus was inferior in strength. Comparative alloy 32 is an example in which the first solution treatment was not performed, and it was mixed grains during the second solution treatment, and the strength and bendability were poor. Comparative alloy 33 is an example in which the second solution treatment was not performed, and the work hardening was remarkable and the bendability was poor. Comparative alloy 34 is an example in which cold rolling was performed only once, and the strength was poor.

[0033]

EFFECTS OF THE INVENTION By adopting the manufacturing method of the present invention, Cu-
It is possible to obtain a high-strength copper alloy that is as good as a Be alloy, which greatly contributes to the miniaturization and thinning of electronic devices, which is extremely useful in industry.

Claims (2)

[Claims] 1. Ti: 0.01 to 4.0% by weight.
A copper alloy containing Cu and the balance Cu and unavoidable impurities, and (1) a first solution heat treatment carried out at a temperature of 800 ° C. or higher for 240 seconds or less and under an average crystal grain size not exceeding 20 μm, (2) First cold rolling performed at a workability of less than 80%, (3) Heat treatment at a temperature of 800 ° C. or higher for 240 seconds or less and an average grain size of 1 to 20 μm or less 2 The solution treatment of the second time, (4) the second cold rolling performed at a working degree of 50% or less, and (5) the aging treatment of 1 hour or more and less than 15 hours at a temperature of 300 to 700 ° C. are sequentially performed. A method for producing a titanium-copper alloy having excellent bendability and stress relaxation characteristics. 2. Ti: 0.01 to 4.0% by weight.
Containing Zn: 0.05 to 2.0%, and C
r, Zr, Fe, Ni, Sn, In, Mn, P and S
In a copper alloy containing 0.01 to 3.0% in total of one or more kinds of i, and the balance of Cu and inevitable impurities, (1) within a temperature of 800 ° C. or higher for 240 seconds and an average crystal grain size. The first solution heat treatment under the heat treatment condition that does not exceed 20 μm, (2) the first cold rolling with a workability of less than 80%, and (3) the average grain size within 240 seconds at a temperature of 800 ° C. or higher. The second solution heat treatment under the heat treatment condition that the diameter does not exceed 1 to 20 μm, (4) the second cold rolling with a workability of 50% or less, (5) at a temperature of 300 to 700 ° C. A method for producing a titanium-copper alloy having excellent bendability and stress relaxation characteristics, which comprises sequentially performing an aging treatment for 1 hour or more and less than 15 hours.