JP2000256814A - Manufacturing method of copper base alloy strip for terminal - Google Patents

Abstract

(57) [Problem] To provide a method of manufacturing a copper-base alloy strip for a terminal which is excellent in all of strength, conductivity, bending workability and stress relaxation resistance. SOLUTION: (1) Cu-Ni-S having a specific composition
a first step of melting the n-P alloy ingot, (2) a second step of hot rolling and quenching at a starting temperature of 650 to 900 ° C. and an ending temperature of 600 to 750 ° C., (3) cold rolling Then, after the intermediate annealing at an annealing temperature of 450 to 600 ° C,
The cold rolling and the intermediate annealing are repeated to reduce the rolling rate to 85.
%, (4) a fourth step of finish cold rolling at a rolling ratio of 50 to 60%, and (5) a fifth step of low temperature annealing at an annealing temperature of 250 to 400 ° C.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a copper base alloy strip for a terminal used for a connector terminal of an automobile or the like.

[0002]

2. Description of the Related Art With the recent development of electronics,
2. Description of the Related Art Terminals such as connector terminals of automobiles are required to have higher density, smaller size, lighter weight, and higher reliability. In addition, as the temperature in the engine room rises due to the high performance of the engine, terminals used in the engine room are also required to have higher reliability and higher heat resistance.

In order to improve the reliability of a terminal such as a connector terminal of an automobile, specifically, it is necessary to have excellent strength, spring characteristics, conductivity, bending workability, stress relaxation resistance, and corrosion resistance. .

[0004] Conventionally, brass, phosphor bronze, Cu-Ni
Copper-based alloys such as -Sn-P-based alloys have been used for terminals.

However, brass, which has been conventionally used as a copper base alloy for terminals, is inexpensive, but has low conductivity, for example, C2600 of 27% IACS, and has a problem in stress relaxation resistance and corrosion resistance. . Phosphor bronze has excellent strength but low electrical conductivity.
% IACS, there was a problem in the stress relaxation resistance, and the price was high and it was not economical.

[0006] Cu-Ni-Sn-P alloys have been developed to compensate for the disadvantages of these two alloys. JP-B-8-9745 describes a method of manufacturing a copper-base alloy strip for a terminal by hot rolling a Cu-Ni-Sn-P-based alloy ingot and then repeating cold rolling and heat treatment. ing.

However, for example, Cu-1.0Ni-0.9Sn-0.05P
Although the copper-base alloy strip (numerical value is% by weight) is excellent in strength and stress relaxation resistance, it has a low electrical conductivity of 38% IACS and does not have sufficient bending workability.

[0008]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and provides a method of manufacturing a copper-base alloy strip for a terminal having excellent strength, conductivity, bending workability, and stress relaxation resistance. With the goal.

[0009]

Means for Solving the Problems The present inventor has conducted intensive studies on the above-mentioned problems in order to achieve the above object.
The present inventors have found that excellent strength, conductivity, bending workability, and stress relaxation resistance can be obtained by selecting an optimum composition and an optimum manufacturing condition of a -Ni-Sn-P alloy.

That is, the method of manufacturing a copper-base alloy strip for a terminal according to the present invention comprises the following first to fifth steps as described in the following (1) to (5).

(1) In the first step, Ni:
0.2-3.0%, Sn: 0.5-2.0%, P: 0.
An alloy ingot containing 0.01 to 1.0%, the balance being Cu and unavoidable impurities, and having a ratio of Ni% to P% of less than 20 is produced.

(2) In the second step, the starting temperature is set at 650 to
Hot rolling and rapid cooling are performed at 900 ° C. and an end temperature of 600 to 750 ° C.

(3) In the third step, (a) cold rolling is performed,
Next, after performing intermediate annealing at an annealing temperature of 450 to 600 ° C., the cold rolling and the intermediate annealing are repeated to reduce the rolling reduction to 85% or more (a plurality of times of cold rolling and intermediate annealing), or (b). After cold rolling with a rolling ratio of 85% or more,
Intermediate annealing is performed at an annealing temperature of 450 to 600 ° C. (one cold rolling / intermediate annealing).

(4) In the fourth step, the rolling reduction is 50-60.
% And finish cold rolling.

(5) In the fifth step, the annealing temperature is set at 250 to
Anneal at low temperature at 400 ° C.

The hot rolled product obtained in the second step of the production method of the present invention has a crystal grain size of 100 μm or less. The intermediate annealed product obtained in the third step has a recrystallized grain size of 5 μm or less.

The copper-base alloy strip produced by the method of the present invention is, in terms of% by weight, Ni: 0.2 to 3.0% and Sn: 0.5.
~ 2.0%, P: 0.01 ~ 1.0%, the balance is composed of Cu and unavoidable impurities, and the ratio of the Ni% to the P% is less than 20. , A structure in which Ni ₃ P compound is uniformly and finely dispersed and precipitated in a matrix, and has a tensile strength of 550 MPa or more and a conductivity of 50%.
Achieve an IACS or more, a minimum bending radius ratio of 1 or less, and a stress relaxation rate of 10% or less.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION (1) Alloying elements The alloying elements added during the smelting of a copper-based alloy ingot in the first step have the following functions and effects in the manufactured alloy strip.

(A) Ni Ni forms a solid solution in a Cu matrix to improve strength, spring characteristics and stress relaxation resistance. The Ni-P intermetallic compound (Ni ₃ P) formed with coexisting P is
It is uniformly and finely dispersed and precipitated in the matrix to improve conductivity and further improve strength, spring characteristics and stress relaxation resistance.

The effect of Ni is as follows.
If the amount is less than 30% by weight, it cannot be sufficiently obtained. Therefore, the Ni composition is required to be at least 0.2% by weight, and preferably at most 3.0% by weight.

(B) Sn Sn forms a solid solution in a Cu matrix to improve strength and spring characteristics.

The effect of Sn is as follows.
If it is less than 10% by weight, it cannot be obtained sufficiently, and the Sn composition is not more than 2.
If it exceeds 0% by weight, it will be saturated. Therefore, the Sn composition needs to be 0.5% by weight or more, and preferably 2.0% by weight or less.

(C) PP is not only a solid solution in the Cu matrix,
Forming a Ni coexist Ni-P intermetallic compound dispersed precipitate (Ni ₃ P). Thereby, strength, conductivity, spring characteristics and stress relaxation resistance are improved. Note that P
Acts as a deoxidizer for molten metal during ingot smelting.

The above-mentioned effects of P cannot be sufficiently obtained when the P composition is less than 0.01% by weight, and become saturated when the P composition exceeds 1.0% by weight. Therefore, the P composition is 0.
It is required to be at least 01% by weight, preferably at most 1.0% by weight.

(D) The value of the ratio of Ni weight% to P weight% In order to sufficiently disperse and precipitate the Ni-P intermetallic compound (Ni ₃ P), the ratio of the Ni weight% to P weight% Value 20
Need to be smaller. When the value reaches 20 or more, for Ni-P intermetallic compound precipitated amount of (Ni ₃ P) becomes extremely small, it can not be conductive and to improve the stress relaxation property.

(2) Hot rolling (a) Solution treatment, (b) In order to adjust the crystal grain size after hot rolling to 100 μm or less (usually 10 μm or more), the starting temperature is 650 to 900 ° C. , End temperature 600 ~
Hot rolling at 750 ° C. Here, the solution treatment is
This is for sufficiently dissolving Ni and P (age precipitation as a Ni ₃ P compound in a later step (described later)). If the starting temperature is lower than 650 ° C., the solid solution of Ni and P tends to be insufficient due to a temperature drop accompanying the progress of rolling, and the above-mentioned aging precipitation effect (aging property) cannot be sufficiently obtained in a later step. On the other hand, 9
If the temperature is higher than 00 ° C., the temperature is close to the melting point, so that hot rolling itself cannot be performed. If the end temperature is lower than 600 ° C., the solid solution of Ni and P becomes insufficient. On the other hand, if it exceeds 750 ° C., it becomes impossible to sufficiently improve the bending workability. Because the crystal grain size is 1
This is because the grain size cannot be adjusted to 00 μm or less (crystal grain size exceeds 100 μm), and the recrystallized grain size (for finish rolling) after cold rolling and intermediate annealing in the subsequent process cannot be adjusted to 5 μm or less. (Refer to cold rolling / intermediate annealing described below).

(3) Quenching The solution-treated hot-rolled product is quenched in order to form a single-phase (supersaturated) structure at room temperature. This rapid cooling may be performed by water cooling, air cooling, oil cooling, or the like, which is usually performed.

(4) Cold Rolling / Intermediate Annealing The hot rolled material obtained by the above-mentioned rapid cooling is usually face-milled. Next, after cold rolling, intermediate annealing is performed at an annealing temperature of 450 to 600 ° C. This cold rolling / intermediate annealing may be performed only once, but may be performed a plurality of times in order to perform cold rolling efficiently. In the case of performing only once, cold rolling is performed at a rolling reduction of 85% or more, and then intermediate annealing is performed at an annealing temperature of 450 to 600 ° C. When performing a plurality of times, cold rolling is performed, then intermediate annealing is performed at an annealing temperature of 450 to 600 ° C., and then the cold rolling and the intermediate annealing are repeated to reduce the rolling ratio to 85% or more. The reason why the cold rolling reduction is 85% or more is that (a) Ni dissolved in hot rolling
Age precipitation of Ni ₃ P compound from P and P, (b) 5μ
This is because the recrystallized grain size is not more than m. Aging precipitation N
Although the particle size of the i ₃ P compound depends on the composition of Ni and P, it is 20
Fine at nm or less. If the recrystallization does not proceed sufficiently in the cold rolling / intermediate annealing or if the recrystallized grain size exceeds 5 μm, it becomes impossible to sufficiently improve the bending workability.

When the rolling reduction is less than 85%, even if the crystal grain size after hot rolling is 100 μm or less, it is difficult to adjust the recrystallized grain size to be subjected to the finish rolling in the subsequent step to 5 μm or less. If the intermediate annealing temperature is lower than 450 ° C., recrystallization does not proceed sufficiently, while if the temperature is higher than 600 ° C., the recrystallized grains become coarser than 5 μm.

(5) Finish Cold Rolling The rolling rate of the finish cold rolling is set to 50 to 60%. 50
%, The strength and the stress relaxation resistance are reduced. On the other hand, when it exceeds 60%, the bending workability is reduced.

(6) Low-Temperature Annealing At the same time that the Ni ₃ P compound is sufficiently precipitated, the strain is removed without causing the recrystallization to proceed, so that sufficient bending workability is provided. Therefore, the low-temperature annealing temperature is set to 25
0 to 400 ° C. If the temperature is lower than 250 ° C., the above-described precipitation reaction does not occur, and the bending workability is reduced. On the other hand, if the temperature exceeds 400 ° C., strain can be removed, but recrystallization proceeds,
Strength and stress relaxation resistance are reduced.

[0032]

EXAMPLES Hereinafter, Examples, Comparative Examples and Conventional Examples will be described.
The present invention will be described more specifically. In addition, the composition of the alloy ingot in these Examples and Comparative Examples is described in Table 1, and the main production conditions are described again. Table 1 shows the composition of the alloy strip in the conventional example.

[Examples 1 and 2] (1) Ingot production of alloy ingots The ratio Ni / P of Ni weight% and P weight% is different (5.7 (Example 1), 12.5 ( Example 2)) Ingots of two compositions were melted using an atmospheric melting furnace.

(2) Hot Rolling / Quenching The alloy ingot was heated at 850 ° C., hot rolled to a thickness of 15.0 mm (hot rolling end temperature: 650 ° C.), and then immersed in water at room temperature. Quenched.

(3) Cold Rolling / Intermediate Annealing The surface of the quenched hot rolled material is beveled to a thickness of 13.0 mm.
And then cold rolled. The cold rolling rate is 95%
The intermediate annealing at 600 ° C. was repeated between the steps until the above was reached. The recrystallized grain size of the strip obtained by the final intermediate annealing was 2.5 μm in all Examples as a result of microscopic examination (see Table 1).

(4) Finish Cold Rolling Finish cold rolling at a rolling reduction of 60% was performed.

(5) Low-Temperature Annealing Low-temperature annealing was performed at 350 ° C. to produce a strip having a thickness of 0.25 mm.

(6) Measurement, etc. The manufactured strip was inspected under a microscope. As a result, in each of the examples, the Ni ₃ P compound was uniformly and finely dispersed and precipitated.

The tensile strength and electrical conductivity of the strip were measured, and the bending workability and the stress relaxation resistance were examined. Table 2 shows the obtained results.

(A) Tensile Strength and Conductivity The tensile strength was measured according to JIS H 2241, and the conductivity was measured according to JIS H 0505.

(B) Bendability The bendability was evaluated by a 90 ° W bending test. The test complies with CES-M0002-6,
90 ° W bending was performed using a jig having a bending radius of 0.1 to 2.0 mm, and the state of the central mountain surface was examined. The bending axis was in a direction parallel to the rolling direction (BadWay). Then, a value obtained by dividing the minimum bending radius R at which cracks and wrinkles did not occur by the plate thickness t, that is, the minimum bending radius ratio R / t was obtained. The smaller the minimum bending radius ratio R / t, the better the bending workability.

(C) Stress Relaxation Resistance In the stress relaxation test, the stress at the center of the test piece was 400MP.
a, and arched at 150 ° C.
After holding for 000 hours, the bending of the test piece was determined using a jig. That is, the stress relaxation rate was calculated by the following equation. In the following equation, L ₀ is the length (mm) of the jig,
L ₁ is the horizontal distance between the sample ends before attaching a bending habit (m
m), L ₂ is a horizontal distance between the sample ends after wearing bending habit (mm).

[0043]

(Equation 1)

[Examples 3 and 4] (1) Ingot smelting of alloy ingot The same procedure as in Examples 1 and 2 was carried out.

(2) Hot Rolling / Quenching The alloy ingot was heated at 850 ° C., hot rolled to a thickness of 5.0 mm (hot rolling end temperature: 650 ° C.), and then immersed in water at room temperature. Quenched.

(3) Cold Rolling / Intermediate Annealing The surface of the quenched hot rolled material was chamfered to a thickness of 4.0 mm and then cold rolled. Cold rolling was repeated with intermediate annealing at 600 ° C. until the rolling reduction reached 85%. The recrystallized grain size of the strip obtained by the final intermediate annealing was 5 μm in all Examples as a result of microscopic examination (see Table 1).

(4) After Finish Cold Rolling The same procedure as in Example 1 was performed.

In the microscopy of the manufactured strips, the Ni ₃ P compound was uniformly and finely dispersed and precipitated in all Examples. Other results are shown in Table 2.

[Comparative Example 1] Except that an alloy ingot with a Ni / P ratio of 20.0% Ni / P was melted, the value of the ratio of Ni weight% to P weight% was melted.
The test was performed in the same manner as in Example 1.

The recrystallized grain size of the strip obtained by the final intermediate annealing was 2.5 μm by microscopic examination (see Table 1). In addition, the microscopic examination of the manufactured strip material showed that the Ni ₃ P compound was relatively non-uniformly dispersed and precipitated because the relatively coarse and fine Ni ₃ P compounds were mixed. Other results are shown in Table 2.

[Comparative Examples 2 and 3] (1) Ingot smelting of alloy ingot The same procedure as in Examples 1 and 2 was carried out.

(2) Hot Rolling / Quenching The alloy ingot was heated at 850 ° C., hot rolled to a thickness of 4.0 mm (hot rolling end temperature: 650 ° C.), and then immersed in water at room temperature. Quenched.

(3) Cold Rolling / Intermediate Annealing The surface of the quenched hot rolled material was chamfered to a thickness of 3.0 mm and then cold rolled. Cold rolling was repeated with intermediate annealing at 600 ° C. until the rolling reduction reached 80%. The recrystallized grain size of the strip obtained by the final intermediate annealing was 15 μm in all comparative examples as a result of microscopic examination (see Table 1).

(4) Finish Cold Rolling and Later The same procedure as in Example 1 was performed.

In the microscopy of the manufactured strip material, the Ni ₃ P compound was uniformly and finely dispersed and precipitated in all the comparative examples. Other results are shown in Table 2.

[Comparative Examples 4 and 5] (1) Smelting of an alloy ingot The same procedure as in Examples 1 and 2 was carried out.

(2) Hot Rolling / Quenching The ingot was heated at 850 ° C., hot rolled to a thickness of 11.0 mm (hot rolling end temperature: 650 ° C.), and then immersed in water at room temperature. Quenched.

(3) Cold Rolling / Intermediate Annealing The surface of the quenched hot rolled material was chamfered to a thickness of 9.0 mm and then cold rolled. Cold rolling was repeated with intermediate annealing at 600 ° C. until the rolling reduction reached 95%. The recrystallized grain size of the strip obtained by the final intermediate annealing was 2.5 μm in all comparative examples as a result of microscopic examination (see Table 1).

(4) Finish Cold Rolling Finish cold rolling at a rolling reduction of 45% was performed.

(5) Low-Temperature Annealing The same operation as in Example 1 was performed.

In the microscopy of the manufactured strip material, the Ni ₃ P compound was uniformly and finely dispersed and precipitated in all the comparative examples. Other results are shown in Table 2.

[Comparative Examples 6 and 7] (1) Ingot smelting of alloy ingot The same procedure as in Examples 1 and 2 was carried out.

(2) Hot Rolling / Quenching The alloy ingot was heated at 850 ° C., hot rolled to a thickness of 22.0 mm (hot rolling end temperature: 650 ° C.), and then immersed in water at room temperature. Quenched.

(3) Cold Rolling / Intermediate Annealing The surface of the quenched hot-rolled material is beveled to a thickness of 20.0 mm.
And then cold rolled. The cold rolling rate is 95%
The intermediate annealing at 600 ° C. was repeated between the steps until the above was reached. The recrystallized grain size of the strip obtained by the final intermediate annealing was 2.5 μm in all comparative examples as a result of microscopic examination (see Table 1).

(4) Finish Cold Rolling Finish cold rolling at a rolling reduction of 75% was performed.

(5) After Low-Temperature Annealing The same as in Example 1.

In the microscopic examination of the manufactured strip material, the Ni ₃ P compound was uniformly and finely dispersed and precipitated in all the comparative examples. Other results are shown in Table 2.

Comparative Examples 8 and 9 (1) Smelting of Alloy Ingot to Finish Cold Rolling The same procedure as in Examples 1 and 2 was carried out.

The recrystallized grain size of the strip obtained by the final intermediate annealing was 2.5 μm in all the comparative examples as a result of microscopic examination (see Table 1).

(2) Low-Temperature Annealing Low-temperature annealing was performed at 200 ° C. to produce a strip having a thickness of 0.25 mm.

(3) Measurement, etc. The measurement was performed in the same manner as in Example 1.

In the microscopic examination of the manufactured strip material, the Ni ₃ P compound was uniformly and finely dispersed and precipitated in all the comparative examples. Other results are shown in Table 2.

[Comparative Examples 10 and 11] Except that low-temperature annealing was performed at 450 ° C to produce a 0.25 mm-thick strip.
It carried out like Comparative Examples 8 and 9.

The recrystallized grain size of the strip obtained by the final intermediate annealing was 2.5 μm in all comparative examples as a result of microscopic examination (see Table 1). In the microscopy of the manufactured strip material, the Ni ₃ P compound was uniformly and finely dispersed and precipitated in all the comparative examples. Other results are shown in Table 2.

[Conventional Examples 1 and 2] The same measurements as in Example 1 were performed on phosphor bronze strips for commercial terminals (Conventional Example 1) and brass strips for commercial terminals (Conventional Example 2) (excluding the microscope). ). Table 2 shows the obtained results.

[0076]

[Table 1]

[0077]

[Table 2]

From the above results, all of the alloy strips of Examples 1 to 4 have a tensile strength of 550 MPa or more and a conductivity of 50 or more.
% IACS or more, the minimum bending radius ratio is 1 or less, and the stress relaxation rate is 10% or less, indicating that all the characteristics are excellent.

On the other hand, as described in the following (1) to (7), the alloy strips of the comparative example and the conventional example have a tensile strength,
At least one of the electrical conductivity, the minimum bending radius ratio, and the stress relaxation rate is inferior outside the above-mentioned regions satisfying Examples 1 to 4.

(1) The alloy strip of Comparative Example 1 having a Ni / P of 20 is inferior in conductivity and stress relaxation rate.

(2) The alloy strips of Comparative Examples 2 and 3 having a small rolling reduction in cold rolling and intermediate annealing and having a large recrystallized grain size are inferior in the minimum bending radius ratio. Also, the conductivity is inferior.

(3) The alloy strips of Comparative Examples 4 and 5 having a small rolling reduction in the finish cold rolling are inferior in tensile strength and stress relaxation rate. Also, the conductivity is inferior.

(4) The alloy strips of Comparative Examples 6 and 7, which have a high rolling reduction in finish cold rolling, are inferior in the minimum bending radius ratio.

(5) The alloy strips of Comparative Examples 8 and 9 having low annealing temperatures in low-temperature annealing are inferior in the minimum bending radius ratio. Also,
The stress relaxation rate is also poor.

(6) The alloy strips of Comparative Examples 10 and 11 having high annealing temperatures in low-temperature annealing are inferior in tensile strength and stress relaxation rate.

(7) Both the alloy (phosphor bronze) strip of Conventional Example 1 and the alloy (brass) strip of Conventional Example 2 are inferior in conductivity and stress relaxation rate.

[0087]

According to the method for producing a copper-base alloy strip for a terminal of the present invention, strength, conductivity, bending workability and stress relaxation resistance are all excellent. Suitable copper-based alloy strips can be provided.

Continuation of the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (reference) C22F 1/00 661 C22F 1/00 661A 683 683 685 685 691 691B 693 693A 694 694A H01R 13/03 H01R 13/03 A

Claims (5)

[Claims] (1) Ni: 0.2 to 3.0% by weight.
%, Sn: 0.5 to 2.0%, P: 0.01 to 1.0%
, The balance consisting of Cu and inevitable impurities, and the ratio of the Ni% to the P% is less than 20, the first step of melting the ingot, (2) the starting temperature is 650 to 900
C., the end temperature is 600 to 750 ° C., the second step of hot rolling and quenching, (3) cold rolling and then annealing at 45 ° C.
After the intermediate annealing at 0 to 600 ° C., the cold rolling and the intermediate annealing are repeated to reduce the rolling reduction to 85% or more.
Step (4), a fourth step of finish cold rolling with a reduction ratio of 50 to 60%, and (5) an annealing temperature of 250 to 40.
A method for producing a copper-base alloy strip for a terminal, comprising a fifth step of performing low-temperature annealing at 0 ° C. 2. (1) Ni: 0.2 to 3.0% by weight.
%, Sn: 0.5 to 2.0%, P: 0.01 to 1.0%
, The balance consisting of Cu and inevitable impurities, and the ratio of the Ni% to the P% is less than 20, the first step of melting the ingot, (2) the starting temperature is 650 to 900
C., a second step in which hot rolling is performed at an end temperature of 600 to 750 ° C. and quenching is performed. (4) the fourth step of finish cold rolling with a reduction ratio of 50 to 60%, and (5) an annealing temperature of 25.
A method for producing a copper-base alloy strip for a terminal, comprising a fifth step of performing low-temperature annealing at 0 to 400 ° C. 3. The hot-rolled product obtained in the second step is 10
The method for producing a copper-based alloy strip for a terminal according to claim 1 or 2, having a crystal grain size of 0 µm or less. 4. The intermediate annealed product obtained in the third step is 5 μm.
The method for producing a copper-base alloy strip for a terminal according to claim 1 or 2, which has a recrystallized grain size of not more than m. 5. The manufactured copper-base alloy strip has a weight percentage of N
i: 0.2 to 3.0%, Sn: 0.5 to 2.0%, P:
Containing 0.01% to 1.0% the remainder being Cu and unavoidable impurities, and the value of the ratio of the said Ni% and said P% has a less than 20 composition, Ni ₃ P compound in the matrix A microstructure having a uniform and finely dispersed and precipitated structure, a tensile strength of 550 MPa or more, a conductivity of 50% IACS or more, a minimum bending radius ratio of 1 or less, and a stress relaxation rate of 10% or less. 5. The method for producing a copper-based alloy strip for a terminal according to any one of 4.