JPS62227052A - Copper-base alloy for terminal and connector and its production - Google Patents

Abstract

PURPOSE:To manufacture the titled copper-base alloy excellent in spring characteristic, strength, electric conductivity, and workability, by subjecting a copper- base alloy having a specific composition successively to hot rolling, cold rolling, annealing, cold rolling, and tension annealing under specific conditions. CONSTITUTION:A slab of the copper-base alloy consisting of, by weight, 1.0-3.0% Sn, 0.05-0.40% Ni, 0.16-0.40% Fe, 0.05-0.10% P, and the balance Cu with inevitable impurities is prepared. This slab is hot-rolled at >=700 deg.C finishing temp. of hot rolling at >=60% draft and cooled through the temp. range from the finishing temp. of hot rolling to <=300 deg.C at >=30 deg.C/min cooling rate. Subsequently, after subjected, if necessary, to pickling treatment, etc., this hot-rolled plate is subjected to the first cold rolling at >=about 50% draft, to annealing at 400-600 deg.C for 5-720min, and to cold rolling until the desired thickness is reached. Then this cold-rolled stock is subjected to tension annealing treatment at 300-750 deg.C for 5-180sec.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a copper-based alloy for terminals and connectors that has excellent spring properties, strength, electrical conductivity, and workability, and a method for producing the same.

[Conventional technology]

Terminals that make up the conductive terminals on the plug side and socket side
Materials for connectors are required to have various properties such as elasticity, strength, stress relaxation properties, and corrosion resistance, regardless of their shape or size, and to be easy to process and inexpensive. Brass and phosphor bronze are the most commonly used materials for such terminals and connectors.

[Problem that the invention seeks to solve]

Brass has the advantages of very good moldability and low cost, but it has extremely poor corrosion resistance and stress corrosion cracking resistance, so it is not suitable for terminals and connectors in the electrical or electronic industry, which is undergoing rapid progress in recent years. The material may be unreliable. Although phosphor bronze has good strength, elasticity, corrosion resistance, and stress corrosion cracking resistance, it is expensive because it contains 3.0% or more of Sn, and it also has problems in that it has poor stress relaxation properties.

[Means to solve problems]

The present invention is a material for terminals and connectors that solves the above-mentioned problems, and has 5nH1.0 to 3.5nH at 2% by weight.
0%, Ni; 0.05-0.40%, Fe; 0
．． 16~0°40%, P; 0.05~0.10%
, the balance being Cu and unavoidable impurities. The copper-based alloy according to the present invention exhibits spring properties and increases strength by adding an appropriate amount of Sn, and exhibits properties favorable for terminals and connectors by precipitation hardening with Fe-P and Fe-N1-P compounds. Points have basic characteristics. and.

As a method for producing the alloy of the present invention for advantageously exhibiting properties desirable for terminals and connectors.

Sn; 1. o~3.0%, N i ; 0.
05~0.40%, Fe: 0.16~0.40%
, P, 0.05 to 0.10%, the balance being Cu and inevitable impurities.

This slab was hot-rolled at a reduction rate of 60% or more and a hot-rolling finishing temperature of 700°C or more, and then
A process of obtaining a hot-rolled sheet by cooling to a temperature of 0°C or lower at a cooling rate of 30°C/min or more.

The obtained hot-rolled sheet is subjected to the first cold rolling with a reduction ratio of 50% or more, and after this first cold rolling, the
A step of annealing at a temperature of 0 to 600°C for 5 to 720 minutes.

A step of reducing the thickness of this annealed material by cold rolling to a desired thickness;

5-180 at a temperature of 300-750℃ after final cold rolling
Process of performing tensidine annealing for seconds.

The present invention provides a method for producing copper-based alloys for terminals and connectors.

The reason for determining the range of the content (% by weight) of additional elements in the copper-based alloy of the present invention is as follows.

Sn is dissolved in the copper matrix to improve strength and spring limit. This effect is not sufficient when the Sn content is less than 1.0%, and on the other hand, when the Sn content exceeds 3.0%, the conductivity and hot workability deteriorate, and it is also economically disadvantageous. For this reason, the Sn content of the copper-based alloy of the present invention is in the range of 1.0 to 2.0%.

Ni is a solid solution in the copper matrix to improve strength, softening resistance, and corrosion resistance, but it is also an element that contributes to the formation of Fe-N1-P-based compounds, which is a characteristic of the alloy of the present invention. It is necessary to add at least 0.05% or more. However, if the content exceeds 0.40%, the R-electricity will drop significantly and it will also be economically disadvantageous. therefore.

The Ni content is 0.05 to 0.40%.

When Fe is dissolved as a supersaturated solid solution in the cavity matrix, it forms a compound with P or Ni and P by aging and precipitates in the copper matrix, improving the strength, spring limit value, and softening resistance. When the Fe content is less than 0.16%, the strength
The spring limit value and softening resistance are low, and if it exceeds 0.40%, the tetraelectricity and moldability will decrease. Therefore, F
The e content is in the range of 0.16 to 0.40%.

P functions as a deoxidizing agent during melting of the alloy of the present invention, and also provides an anti-oxidation effect of Sn and Fe, thus playing an important role in obtaining a healthy ingot. The supersaturated solid solution of P in the copper matrix is Fe or F.
Together with e and Ni, it forms a Fe-P compound and a Fe-Nt-P compound. If the P content is less than 0.05%, such effects will not be sufficient, and if it is added in excess of 0.10%, the conductivity and processability will deteriorate. therefore,
The P content is in the range of 0.05 to 0.10%.

The copper-based alloy according to the present invention having such a component composition has terminal and hardening properties mainly due to the synergistic effect of solid solution strengthening by Sn and Ni and precipitation hardening of Fe-P-based compounds and Fe-NL-P-based compounds. It can have both the strength and spring limit value required for the connector, and also have sufficient electrical conductivity.

These properties can be advantageously brought out by appropriately controlling the manufacturing conditions when processing a slab to a desired thickness through hot rolling and cold rolling. The details of the manufacturing method will be explained below.

Hot rolling process A slab having the composition according to the present invention is produced by melting and casting, and this slab (ingot) is subjected to hot rolling. It is preferable to carry out the hot rolling with a reduction ratio of 60% or more, preferably 90% or more, and a hot rolling finishing temperature of 700° C. or more. As a result, the cast structure can be completely crushed, and the influence of segregation occurring in the ingot can be eliminated.

Then, cooling is performed in a temperature range from the hot rolling finishing temperature to 300° C. or less at a cooling rate of 30° C./min or more. This cooling is preferably carried out by performing rapid water cooling immediately after hot rolling, thereby making it possible to obtain a hot rolled material in which Fe, Ni and P are completely dissolved in solid solution. If this cooling after hot rolling is performed at a cooling rate slower than 30°C/min, these elements will precipitate during the cooling process, resulting in coarse Fe-P system, F
e-N1-P type compounds are generated. Even if this temperature range is quenched as described above, the quenching start temperature will be 700
If the temperature is lower than 'C, or if the cooling rate is slower than 30°C/min even if the quenching start temperature is 700°C or higher, coarse precipitates will precipitate during this time. The precipitates precipitated at this stage are incompatible with the parent phase, and improvements in the spring limit value and stress relaxation properties cannot be expected from this. Therefore, one feature of the present invention is that hot rolling conditions are adopted such that a hot rolled sheet in which Fe, Ni, and P are completely dissolved in solid solution is obtained. The cooling end point temperature during this rapid cooling is 3o.
It is sufficient if the temperature is below 0°C.

This is because precipitation of Fe--P compounds and Fe--N1--P compounds does not substantially occur at temperatures below 300.degree.

The hot-rolled sheet obtained in the pre-process of cold rolling and annealing is then subjected to surface grinding or pickling as necessary, and then cold-rolled to the desired sheet thickness by performing cold rolling with annealing a necessary number of times. However, by adjusting the initial cold rolling and annealing conditions appropriately, fine Fe-P and Fe-N1-P compounds are precipitated uniformly at this stage.

First, the first cold rolling has a reduction rate of 50% or more.

It is preferably carried out at 80% or more, and annealing after this first cold rolling is carried out at a temperature of 400 to 600° C. for 5 to 720 minutes. This initial cold rolling and annealing conditions are extremely important in the present invention.

If the reduction ratio in the first cold rolling is less than 50%, the rolling structure will not be homogenized, and the Fe-P system will be formed in the subsequent annealing.

The F e-N i-P compound cannot be precipitated uniformly and finely. If this first annealing is carried out at a temperature exceeding 600°C, the precipitates will aggregate and become coarse, and further improvements in the spring limit value and moldability cannot be expected.

At a temperature below 400°C, the time required for precipitation is too long, so the first annealing may be performed at a temperature of 400 to 600°C, and the annealing time may be in the range of 5 to 720 minutes.

If the annealing time is less than 5 minutes, the formation of precipitates is insufficient;
Furthermore, recovery of elongation by this annealing is not sufficient, but if the annealing is performed for a long time, such as over 720 minutes, the growth of fine precipitates will proceed, which is not preferable and is also an economic burden.

By appropriately performing the first cold rolling and annealing in this manner, a material is obtained in which Fe-P and Fa-Ni-P compounds are finely and uniformly precipitated.

Thereafter, cold rolling may be performed as many times as necessary until the desired thickness is achieved. If cold rolling is performed several times during this process, intermediate annealing may be performed.

Then, after cold rolling to the desired thickness,
Perform a tension annealing treatment at a temperature of 300-750'C for 5-180 seconds. By this tension annealing, it is possible to improve the spring limit value and recover the elongation, and it is possible to obtain a product that is homogeneous and has good flatness. When carrying out this tension annealing treatment, if the temperature is less than 300℃, the effect of local residual stress removal is small; on the other hand,
If the temperature exceeds 750℃, the material will soften even for a short time, so the treatment temperature for tension annealing is 300℃ to 750℃.
It is best to do this at a temperature of 50°C. Further, regarding the treatment time, if it is less than 5 seconds, a homogeneous material cannot be obtained, and if it exceeds 180 seconds, no difference will be seen in the effect, so it is preferable to set the treatment time to a range of 5 to 180 seconds.

Examples of the present invention are listed below.

Example A copper-based alloy of Nll-7 whose chemical composition values (wt%) are shown in Table 1 was melted using a high frequency vacuum melting furnace, and a 40 m
It was cast into an ingot measuring m x 40 mm x 140 mm.

This ingot was cut into pieces of 40 mm x 40 mm x 20 mm, and after soaking this ingot at 850°C,
- Hot rolling was carried out to a length of 51+1 m, and the sample was cooled in water from a temperature of 750°C.

The obtained hot-rolled sheet was cold-rolled for the first time to a thickness of 1
It was cold rolled to a thickness of 0.0 mm and then annealed at 550° C. for 60 minutes. Then, it was cold rolled at a rolling reduction of 50%.

A cold-rolled plate with a thickness of 0.5 mm was obtained. 10 of the obtained cold-rolled sheets
Tension annealing was performed at 400°C for 20 seconds while applying a tension of Jf/mm''.The material after this treatment was used as the test material.In addition, 1lh8 in the table did not go through the above manufacturing process. , commercially available phosphor bronze annealed at low temperature.

The tensile strength, elongation, electrical conductivity, spring limit value, and softening temperature of each test material were measured and subjected to a 90° bending test. These measurement results are also listed in Table 1.

The tensile strength and elongation were measured in accordance with JIS-Z-2241, the electrical conductivity was measured in accordance with JIS-H-0505, and the spring limit value was measured in accordance with JIS-11-3130. The softening temperature is the temperature at which the hardness after heating becomes 80% of the initial hardness when the sample is heated at that temperature for 30 minutes. 90°
- The bending test was conducted in accordance with the regulations of BS-MOOO2-6. In other words, the condition of the Chuo Koriyama surface when bending was performed for 900 degrees with an R・0, 2 mm jig, and one crack occurred. The results were evaluated as ×, those with slight wrinkles were evaluated as △, and those that were good were evaluated as O.

Furthermore, the stress relaxation properties of the present invention alloy No. 3 and comparative alloy No. 8 shown in Table 1 were measured, and the results are shown in Table 2. In the test, U-shaped bending was performed so that the stress at the center of the test piece was 80% of the yield strength, and the bending after holding at a temperature of 150° C. for 1000 hours was calculated as the stress relaxation rate using the following formula.

Stress relaxation rate C1) = ((t, + - t, z)/(t, +
-L6))

Table 2 The following is clear from the results in Table 1.

The alloys 11hl to 4 according to the present invention all have a tensile strength of 50 kgf/mm" or more and a spring limit of 45 kgf/m.
m" or higher, has excellent electrical conductivity 3 bending workability, and has a high softening temperature. Therefore, it can be seen that it is an extremely excellent copper-based alloy for terminals and connectors.

On the other hand, Comparative Alloy No. 5, which has a smaller Sn content than specified in the present invention, has low strength and spring limit values.

Further, the comparative alloy No. 6 containing more Fe than specified in the present invention has poor bending workability, and the comparative alloy No. 7 containing no Fe has poor heat resistance.

From the results in Table 2, it can be seen that the alloy of the present invention has superior stress relaxation properties compared to phosphor bronze, which is a typical conventional material for terminals and connectors.

Claims (2)

[Claims] (1) In weight%, Sn; 1.0 to 3.0%, Ni
;0.05~0.40%, Fe;0.16~0.40%
, P; 0.05 to 0.10%, the balance being Cu and inevitable impurities. A copper-based alloy for terminals and connectors. (2) In weight%, Sn; 1.0 to 3.0%, Ni
;0.05~0.40%, Fe;0.16~0.40%
, P: 0.05 to 0.10%, the balance being Cu and unavoidable impurities. A step of manufacturing a slab of copper-based alloy, the slab is rolled at a reduction rate of 60% or more and a hot rolling finishing temperature of 700°C or more. After hot rolling at
A process of obtaining a hot-rolled sheet by cooling to a temperature of 0°C or lower at a cooling rate of 30°C/min or more. The hot-rolled sheet is cold-rolled for the first time at a reduction rate of 50% or more, and after this first cold-rolling, the
A process of annealing at a temperature of 00°C for 5 to 720 minutes, a process of reducing the thickness of the annealed material by cold rolling to a desired thickness, and a process of reducing the thickness of the annealed material at a temperature of 300 to 750°C after the final cold rolling. 5-180
A method for producing copper-based alloys for terminals and connectors, which involves the process of performing tension annealing for seconds.