JPH07268452A - Electrically conductive spring material and its production - Google Patents

Abstract

PURPOSE:To obtain a material constituted of an Fe-Cu alloy and having high spring limit value and high electrical conductivity. CONSTITUTION:A material contg., by weight, 30 to 70% Cu, 0.2 to 5.0% Al, 3.0 to 9.0% Cr, and the balance Fe with inevitable impurities is subjected to aging treatment at 300 to 500 C for 30 to 180 min. This is the electrically conductive spring material furthermore contg., as alloy components, respectively 0.1 to 3.0% of one or >=two kinds among Mn, Si and Zn.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a conductive spring material excellent in both conductivity and strength and a method for manufacturing the same.

[0002]

2. Description of the Related Art Spring contact materials are widely used in switches and connectors and are required to have both electrical conductivity and strength. These materials are generally Cu-based materials containing phosphor bronze or nickel-white Cu as a main component and 42 alloy (42% N
i-Fe) and Fe-based materials whose main component is Fe of Kovar metal.

Cu-based materials are mainly used for the purpose of emphasizing conductivity, and Fe-based materials are applied for the purpose of emphasizing the strength, but no material having these two characteristics is found. In particular, a spring contact material mainly composed of Cu has good electric conductivity, but is poor in strength, so that further improvement in strength is required in accordance with recent miniaturization of electronic parts. Beryllium copper can be cited as a material that meets this requirement.
This alloy specified in IS1720 is very expensive and thus has limited fields of use.

[0004]

SUMMARY OF THE INVENTION In view of the above situation, it is an object of the present invention to provide a spring contact material having both electric conductivity and strength and a method for manufacturing the spring contact material.

[0005]

In order to increase the electric conductivity, it is desirable to reduce the number of additive elements so as to approach pure Cu as much as possible. On the other hand, in order to improve the strength, it is necessary to add strain to the matrix or to add various elements to form an alloy in order to suppress the movement of dislocations. As described above, in order to obtain the two characteristics of electric conductivity and strength at the same time, there is no choice but to take contradictory methods, which is very difficult to realize. The present inventors
In order to solve such a problem, attention has been paid to the design of an alloy composed of two phases, that is, a phase having good electric conductivity and a phase having high strength.
The possibility was found in the -Fe alloy.

The inventors of the present invention have found that Fe and Cu are elements that cause two-phase separation.
However, the solid solution of Fe in Cu should be about 3%,
That is, it was noted that the metallic structure was a mixture of Fe phase and Cu phase, and the mixing ratio thereof was not affected by temperature so much and was almost constant. Then, the present invention has been completed by securing the conductivity by the Cu phase and the strength by the Fe phase.

The present invention has the following matters as its gist. % By weight, Cu 30-70%, Al 0.2-
5.0%, Cr 3.0-9.0%, or even M
One or more of n, Si and Zn is 0.1
˜3.0%, the balance Fe and unavoidable impurities, and an aging treatment at 300 to 500 ° C. for 30 to 180 minutes. % By weight, Cu 30-70%, Al 0.2-
5.0%, Cr 3.0 to 9.0%, or 1% or more of Mn, Si and Zn to 0.
An alloy containing 1 to 3.0% by weight and the balance Fe and unavoidable impurities is melted at 1400 to 1700 ° C., poured into a mold, cooled, and then hot rolled at a temperature of 800 ° C. or more to form a plate. And then cold rolling, slitting into a predetermined width, and further holding in a furnace at a temperature of 300 to 500 ° C. for 30 to 180 minutes.

The present invention will be described in detail below. First,
The role of the additive element of the alloy of the present invention and its composition range will be described. Cu is an element that enhances electrical conductivity,
If it exceeds 70%, the strength at room temperature and high temperature will decrease, and the price will increase. If it is less than 30%, the electrical conductivity becomes unpractical and the oxidation resistance also deteriorates. Therefore, 30 to 70% is set as the appropriate range. The Cu concentration can be selected within this range, and when the importance is attached to the electric conductivity, it is preferably close to 70%. On the other hand, when the importance is attached to the strength, a low value close to 30% is suitable.

Al contributes to improvement of oxidation resistance and workability at high temperature. If it exceeds 5%, the electrical conductivity required for the spring contact material deteriorates, and the solder wettability deteriorates, resulting in a high defective rate. Therefore, the range is limited to 0.2 to 5.0%. Cr dissolves in the Fe phase and improves the rust resistance of the Fe phase. It also contributes to oxidation resistance at high temperatures. Cr
If the amount is 3% or less, these effects are weakened, while if it exceeds 9%, the workability is reduced. Therefore, 3.0 to 9.0% is set as an appropriate range.

All of Mn, Si and Zn contribute to solder wettability and are excellent in oxidation resistance. Of these elements, one or two or more of them have no effect at 0.1% or less, and the electrical conductivity decreases at 3% or more, so 0.1 to 3% was made the appropriate range.

In order to use it as a spring material, it is necessary to increase the strength. As a method therefor, an additional element was precipitated by aging treatment to increase the dislocation growth and strengthen the precipitation. It was also aimed that the effect of preventing electron scattering and improving electric conductivity can be obtained.

The results of investigating the influence of the aging treatment on the strength and spring characteristics of the spring material are shown below. An alloy included in the composition range of the alloy of the present invention, ie, Cu 50%,
1 and 2 show the relationship between the aging temperature and the hardness and the spring limit value when an alloy consisting of 40% Fe, 5% Cr and 5% Al was aged at each temperature for 1 hour. The spring limit value is an index of how much stress the material can retain the spring property, and is calculated by calculating the surface stress from the load when the sample reaches a predetermined residual strain. For example, phosphor bronze is 25 kg / mm ² , beryllium copper is 70 kg / mm ² .
^{Is 2} . The test method is specified in JIS H3130.

From FIG. 1 and FIG. 2, the aging temperature is 200 to
It is effective at 700 ° C., and a more preferable range is 200 to
It can be seen that the temperature is 500 ° C.

Next, a method for producing the alloy of the present invention will be described. The melting atmosphere in which the respective metals are mixed and melted so that they fall within the composition range of the alloy of the present invention can be the atmosphere, vacuum, or a non-oxidizing gas atmosphere. 1400-170
After the temperature is raised to 0 ° C. to dissolve, it is poured into a mold and cooled. Then, hot rolling is performed at a rolling temperature of 800 ° C. or higher, and after rolling to a plate of about several mm, cold rolling is performed and slit cutting is performed to a predetermined width.

After that, it is held in a furnace controlled in a temperature range of 300 to 500 ° C. and subjected to an aging treatment. Hold time is 30
It is possible from 3 minutes to 3 hours, but 1 hour is industrially appropriate.

[0016]

EXAMPLES The present invention will be further described below based on examples. Example 1 A plate of a Cu-Al-Cr-Fe alloy whose chemical composition is shown in Table 1 was prepared, and a sample having a width of 10 mm and a length of 100 mm was cut out from the plate. Then, after being kept in an atmospheric furnace at 300 ° C. for 1 hour and subjected to an aging treatment, various characteristics such as a spring limit value, hardness, and electric conductivity were evaluated. The results are shown in Table 2 together with those not subjected to the aging treatment.

Example 2 Cu 52 kg, Fe 43 kg, Al 2.3 kg,
5 kg of Cr and 2.2 kg of Mn were mixed, heated to 1600 ° C. in a vacuum furnace to melt, and then injected into a mold. The chemical composition after cooling is as shown in Table 1, and Mn is further added to the composition of Example 1. From this, cut out a sample of 10 mm width x 100 mm length, 3
A comparison was made between those aged at 50 ° C. for 2 hours and those not aged. The results are shown in Table 2.

Example 3 Cu-Al-Cr-Fe-Si whose chemical components are shown in Table 1
Create an alloy plate, and from this, width 10 mm, length 10
A 0 mm sample was cut out and then subjected to an aging treatment at 400 ° C. for 30 minutes. Table 2 shows the spring limit value, tensile strength, and electrical conductivity characteristic values of the samples that were aged and those that were not, together with the results of the solder wettability samples. In the solder wettability sample, 0.2 g of solder was placed in the center of the sample, and the spread diameter of the solder was measured after holding at 200 ° C. for 30 seconds.

[0019]

[Table 1]

[0020]

[Table 2]

From the results shown in Tables 1 and 2, the materials in the composition range of the alloy of the present invention are excellent in strength and spring characteristics,
It is also seen that aging treatment of this significantly increases the result.

[0022]

As described above, according to the present invention, it is possible to provide a conductive spring material having both a high spring limit value and a high electric conductivity.

[Brief description of drawings]

FIG. 1 is a diagram showing the effect of aging temperature on the hardness of the alloy of the present invention.

FIG. 2 is a diagram showing the effect of aging temperature on the spring limit value of the alloy of the present invention.

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Claims (4)

[Claims] 1. By weight percent, Cu 30-70%, Al
0.2-5.0%, Cr 3.0-9.0%, balance Fe
And an alloy consisting of unavoidable impurities, which is 300 to
A conductive spring material characterized by being aged for 30 to 180 minutes at 500 ° C. 2. The alloy further comprises Mn, Si and Zn.
The conductive spring material according to claim 1, containing 0.1 to 3.0% by weight of one kind or two or more kinds thereof. 3. By weight%, Cu 30-70%, Al
0.2-5.0%, Cr 3.0-9.0%, balance Fe
And an alloy consisting of inevitable impurities from 1400 to 170
After melting at 0 ° C, it is poured into a mold, cooled, and then hot-rolled at a temperature of 800 ° C or higher to form a plate, which is then cold-rolled, slit-cut to a predetermined width, and then at a temperature of 300 to 500 ° C. The method for producing a conductive spring material is characterized by holding in a furnace for 30 to 180 minutes. 4. The alloy further comprises Mn, Si and Zn.
The method for producing a conductive spring material according to claim 3, wherein 0.1 to 3.0% by weight of one kind or two or more kinds is contained.