WO2019091483A1 - Elastic electrical contact composite material for replacing beryllium copper and preparation method therefor - Google Patents

Abstract

Disclosed is a method for preparing an elastic electrical contact composite material. The preparation method comprises: compounding and rolling a stainless steel strip and a Cu strip to prepare a stainless steel (1)/Cu (2) two-layer or stainless steel (1)/Cu (2)/stainless steel (1) three-layer composite strip; performing diffusion heat treatment on the stainless steel (1)/Cu (2) two-layer or stainless steel (1)/Cu (2)/stainless steel (1) three-layer composite strip; performing cyclic treatment on the heat-treated composite strip multiple times; withdrawing and straightening the heat-treated composite material strip; cleaning the withdrawn and straightened composite strip in phases and then slitting same; and punching the slitted composite strip to obtain the desired elastic electrical contact material. With the preparation method by combining phased heat treatment and multiple cyclic treatments, an environment-friendly elastic electrical contact composite material with a high strength, a high elasticity and a low resistivity can be prepared; and the process is simple, the cost is low, and there is no special requirement for a device.

Description

Elastic electric contact composite material replacing beryllium copper and preparation method thereof Technical field

The invention relates to the field of electrical devices, in particular to an elastic electric contact composite material for replacing beryllium copper in a field of new material application and a preparation method thereof.

Background technique

Beryllium copper alloy is widely used in elastic electrical contact elements of electrical switches due to its excellent mechanical, chemical and electrical properties such as high strength, elasticity, fatigue strength, corrosion resistance, electrical conductivity and non-magnetic properties. However, cockroaches and their compounds have enormous toxic side effects on the human body and are one of the serious industrial hazards. Therefore, it is particularly important to find a low-lying or even flawless environmentally-friendly electrical contact elastic material.

301, 304 and 316L stainless steels have been widely used in the industrial, furniture and decorative industries and food and medical industries due to their good plasticity, toughness, tensile strength and corrosion resistance. Compared with beryllium copper alloy, 301 (or 304, 316L) stainless steel has 10% higher tensile strength, 1 times higher elongation, 18% higher hardness and 35% higher melting point, and the cost of stainless steel is lower than that of pure Cu and BeCu. Therefore, a new material that combines the characteristics of stainless steel and copper, namely stainless steel/Cu, replaces the new material of beryllium copper material, and the physical properties are close to or better than that of beryllium copper (slightly high elasticity and slightly lower resistance). The actual application environment is obviously superior to beryllium copper. In the application environment of more than 200 °C, beryllium copper will appear to be obviously weak with the increase of temperature and use time, that is, its strength is reduced, the elasticity is decreased, and stainless steel/ Cu composite products not only achieve excellent mechanical and electrical properties, but also save costs, and can continue to work normally in environments exceeding 400 °C.

After searching, the research literature on the preparation methods of stainless steel copper-clad materials at home and abroad was found as follows:

Literature [1]. Chinese invention patent: composite method of copper and stainless steel, application number: 03158378.4, publication number: CN 1262383 C;

Literature [2]. Chinese invention patent: diffusion welding method of copper alloy and stainless steel, application number: 200910254462.5, publication number: CN 101745736 B;

[3]. Chinese invention patent: a preparation method of copper-steel composite material, application number: 201210054764.X, publication number: CN 102671942 A;

[4]. Chinese utility model patent: 钽-copper-stainless steel explosion composite board, application number: 20112055461.0, publication number: CN 202021875 U;

Literature [5]. Chinese invention patent: a production method of 304 stainless steel and pure copper cold composite strip, application number: 201210322873.5, publication number: CN 102794300 B;

[6]. Chinese invention patent: a stainless steel composite board and its manufacturing method, application number: 201310213211.9, publication number: CN 103264546 B.

At present, the preparation methods of stainless steel/Cu composite materials are mainly divided into four types: welding, explosive composite, cold rolling composite, and hot rolling. The welding method can be further divided into resistance brazing, friction welding, solid phase diffusion welding and liquid phase diffusion welding [Documents 1-3]. The welding method involves simple processing equipment, which can effectively compound stainless steel plates and Cu or other metal substrates. However, due to the use of solder and high temperature treatment, brittle materials such as intermetallic compounds are easily generated at the welded joint surface, resulting in the mechanics of the welded joint surface. Poor performance.

Although the method of explosive composite can solve the problem of intermetallic compounds in the composite interface, the thickness of the composite is limited due to its process characteristics, and the environmental pollution and safety problems caused by the explosion are serious [Document 4].

The single cold rolling→annealing preparation method can effectively improve the surface oxidation, end surface rust, and unevenness of the composite layer, and the method has the advantages of high production efficiency and high dimensional accuracy, but single rolling makes The processing deformation is small and cannot meet the production requirements of thin plate materials (≤0.5mm) [Document 5].

The hot rolling method can achieve rapid and effective compounding of materials, and can produce larger size samples, but the rolling thickness is difficult to control, and the surface quality is poor, which is commonly used in the production of blanks [Document 6].

Summary of the invention

The present invention is directed to the deficiencies and shortcomings of the prior art described above, and provides an elastic electric device for replacing beryllium copper with physical properties close to or superior to beryllium copper (slightly high elasticity, slightly lower electrical resistance), stable thermal performance, and low cost. The contact composite material and the preparation method thereof further greatly improve the opening and closing performance and the service life of the electrical switch.

To achieve the above object, the present invention adopts the following technical solutions:

According to a first object of the present invention, there is provided a method of preparing an elastic electrical contact composite, the method comprising the steps of:

The first step: composite rolling of stainless steel strip and Cu strip to prepare stainless steel/Cu two-layer or stainless steel/Cu/stainless steel three-layer composite strip;

The second step: the stainless steel/Cu two-layer or stainless steel/Cu/stainless steel three-layer composite strip is subjected to diffusion heat treatment;

The third step: the above-mentioned heat-treated composite material strip is subjected to a plurality of (rolling→softening heat treatment) cycle treatment;

The fourth step: the above-mentioned heat-treated composite material strip is subjected to tension correction;

Step 5: After the above-mentioned stretched composite material strip is cleaned in stages, the strip is divided;

Step 6: The composite strip after the above striping is punched to prepare an elastic electrical contact material of a desired size.

Further, after the sixth step, the seventh step is performed, that is, the elastic electrical contact material is cleaned and packaged.

Preferably, in the first step:

The composite rolling adopts cold rolling composite, the strip width is 100 mm to 650 mm, the rolling deformation is 50% to 70%, and the recombination rate is 1.5 m/min to 4 m/min.

Preferably, in the second step:

The diffusion heat treatment has a temperature of 800 ° C to 1083 ° C, preferably 850 ° C to 950 ° C, continuous annealing, a rate of 1 m / min to 3 m / min, an atmosphere of H ₂ or N ₂ , a gas flow rate of ≥ ₂ m ³ / h. The diffusion heat treatment can further strengthen the bonding strength between different layers by atomic diffusion. When the temperature is lower than 800 ° C, the atom diffusion is slow, and when the temperature is higher than 1083 ° C, the Cu layer melts due to reaching the melting point. Further, since Cu and Fe are easily oxidized at a high temperature, an inert gas or a reducing gas is used as a protective atmosphere.

Preferably, in the third step:

The above-mentioned multiple (rolling→softening heat treatment) cycle process is adopted, that is, the deformation amount of the rolling is calculated according to the required thickness of the finished product, and the cold rolling process is performed, and one cold rolling and one heat treatment are sequentially and cyclically processed, that is, : cold rolling 1 → heat treatment → cold rolling 2 → heat treatment → cold rolling 3 → heat treatment..., the rolling deformation of each cold rolling process before the last cold rolling is 15% to 35%, and this cycle is controlled. The uniformity of the thickness of the strip after rolling, and no defects such as cracking and crushing during the rolling process, and the ductility of the composite strip and the elasticity of the finished electrical contact material are ensured according to the last cold rolling deformation and the corresponding heat treatment;

The softening heat treatment adopts continuous annealing, the temperature is 900 ° C to 1050 ° C, the rate is 0.5 m / min to 3.0 m / min, the atmosphere is H ₂ or N ₂ , the gas flow rate is ≥ ₂ m ³ / h, and the softening heat treatment can The composite strip is restored to a soft state to ensure the ductility of the composite strip during the rolling process.

Preferably, in the fourth step:

The tensile elongation is controlled to be within 0.5%, preferably from 0 to 0.3%, and the tape thickness tolerance is ±0.01 mm.

Preferably, in the fifth step:

The staged cleaning brush is cleaned by different temperature division stages. The first stage is: adding degreasing agent to the clean water at a temperature of 40 ° C to 60 ° C, and cleaning the surface of the composite strip with a soft brush to remove the surface of the composite strip. Grease; second stage: temperature is 40 ° C ~ 60 ° C, the surface of the composite strip is cleaned in clean water to remove the residual degreaser on the surface of the composite strip; the third stage (only for stainless steel / Cu two-layer materials): At room temperature, an environmentally-friendly protective agent is added to the clean water to passivate the surface of the composite strip; the fourth stage: the strip is dried at a temperature of 60 ° C to 80 ° C. By stepwise cleaning, the surface impurities of the composite material are removed, and the passivation treatment can reduce the oxidative discoloration of the composite material during transportation, storage and work.

The striping rate is 10 m/min to 30 m/min, and the strip width is 10 mm to 300 mm.

According to a second object of the present invention, there is provided an elastic electrical contact composite material prepared by the above method, wherein the elastic electrical contact composite material is made of a stainless steel/Cu two-layer or a stainless steel/Cu/stainless steel three-layer composite material tape. The thickness of the stainless steel layer in the two-layer composite strip is 20-80% of the thickness of the entire composite strip; in the three-layer composite strip, the thickness of the single-sided stainless steel layer is 20%-45% of the entire composite strip.

Preferably, in the composite tape, Cu is copper, that is, T2 copper, and the stainless steel is 301, 304 or 316L.

Compared with the prior art, the present invention has the following beneficial effects:

It can be seen from the process implemented by the above technology of the present invention that, on the one hand, by adopting a combination of staged heat treatment and multiple (rolling→softening heat treatment) cycle treatment, the welding interface is not well contacted and the diffusion is uneven. Hot rolling has concentrated thermal stress, low strength, small deformation of single cold rolling, and insufficient environmental problems such as explosive composite. The prepared samples maintain good elasticity and thermal stability regardless of morphology, size and mechanical life. And electrical performance, etc. meet the customer's requirements for use; on the other hand, through the staged cleaning, the surface impurities of the composite material are removed, and the passivation treatment can reduce the oxidation of the composite material during transportation, storage and work. Discoloration.

The invention can prepare an environment-friendly electric contact elastic material with high strength, high elasticity and low electrical resistivity, and has simple process and low cost, and has no special requirements on equipment.

The method of the invention has the advantages of low cost, simple process, large-scale production and good economical use value.

DRAWINGS

1 is a cross-sectional structural view showing a two-layer composite of a stainless steel/Cu tape in some embodiments of the present invention;

2 is a cross-sectional structural view of a three-layer composite of a stainless steel/Cu/stainless steel strip used in some embodiments of the present invention;

among them:

1 is a stainless steel, that is, a layer of 301, 304 or 316L, and 2 is a copper layer.

Detailed ways

The invention will now be described in detail in connection with specific embodiments. The following examples are intended to further understand the invention, but are not intended to limit the invention in any way. It should be noted that a number of variations and modifications may be made by those skilled in the art without departing from the inventive concept. These are all within the scope of protection of the present invention.

Embodiment 1

For example, a two-layer elastic electrical contact composite material as shown in FIG. 1 is prepared, wherein 1 is a 304 stainless steel layer and 2 is a Cu layer: the prepared elastic electrical contact composite material is made of a stainless steel/Cu two-layer composite material strip, in two layers. The thickness of the stainless steel layer in the composite strip is 20-80% of the thickness of the entire composite strip;

The first step: composite rolling of 304 stainless steel strip and Cu strip to prepare 304/Cu two-layer composite strip, using cold rolling composite, the strip width is 250mm, the rolling deformation is 60%, and the recombination rate is 1.5m/min;

The second step: the 304/Cu two-layer composite strip is subjected to diffusion heat treatment at a temperature of 875 ° C, using continuous annealing at a rate of 1.0 m / min, the atmosphere is H ₂ , and the gas flow rate is 3 m ³ /h;

The third step: the above-mentioned heat-treated composite strip is subjected to three cycles (rolling→softening heat treatment), and the rolling deformation of each cold rolling step before the cold rolling of the finished product is 15%, and the softening heat treatment is performed at a temperature of 925 ° C. The rate was 0.7 m/min, the atmosphere was H ₂ , the gas flow rate was 3 m ³ /h, and the cold rolling deformation of the finished product was 50%.

The fourth step: the above-mentioned heat-treated composite material strip is subjected to tension correction, and the tensile elongation is controlled to be within 0.5%, preferably 0 to 0.3%, and the material strip thickness tolerance is ±0.01 mm;

Step 5: After the above-mentioned tensioned composite strip is cleaned in stages, it is divided into strips and washed at different temperatures. The first stage: adding environmentally friendly degreaser in clean water at a temperature of 40 ° C, using a soft brush pair The surface of the composite strip is cleaned to remove the grease on the surface of the composite strip; the second stage: the temperature is 40 ° C, the surface of the composite strip is cleaned in clean water to remove the residual degreaser on the surface of the composite strip; the third stage: at room temperature In the clean water, an environmentally-friendly protective agent is added to passivate the surface of the composite strip; the fourth stage: the strip is dried at a temperature of 60 ° C; the striping rate is 10 m/min, and the strip width is 12 mm.

Step 6: The composite strip after the above striping is punched to prepare an elastic electrical contact material of a desired size.

Step 7: Clean and package the above elastic electrical contact materials.

Embodiment 2

For example, a two-layer elastic electrical contact composite material as shown in FIG. 1 is prepared, 1 is 304 stainless steel, and 2 is Cu:

The first step: composite rolling of 304 stainless steel strip and Cu strip to prepare 304/Cu two-layer composite strip, using cold rolling composite, the strip width is 400mm, the rolling deformation is 75%, and the recombination rate is 3m/min;

The second step: the 304/Cu two-layer composite strip is subjected to diffusion heat treatment at a temperature of 900 ° C, using continuous annealing at a rate of 2.0 m / min, the atmosphere is H ₂ , and the gas flow rate is 3 m ³ /h;

The third step: the above-mentioned heat-treated composite material strip is subjected to three cycles (rolling→softening heat treatment), and the rolling deformation amount is 35% in each cold rolling step before cold rolling, and the temperature is 1000° C. The rate is 2.5 m/min, the atmosphere is H ₂ , the gas flow rate is 3 m ³ /h, and the cold rolling deformation of the finished product is 50%.

The fourth step: the above-mentioned heat-treated composite material strip is subjected to tension correction, and the tensile elongation is controlled to be within 0.5%, and the thickness tolerance of the material belt is ±0.01 mm;

Step 5: After the above-mentioned stretched composite material belt is cleaned in stages, it is divided into strips and washed at different temperatures:

The first stage: adding an environmentally friendly degreaser to the clean water at a temperature of 50 ° C, using a soft brush to clean the surface of the composite strip to remove the surface grease of the composite strip;

The second stage: the temperature is 50 ° C, the surface of the composite strip is cleaned in clean water to remove the residual degreaser on the surface of the composite strip;

The third stage: adding an environmentally-friendly protective agent to the water at room temperature to passivate the surface of the composite strip;

The fourth stage: drying the strip, the temperature is 70 ° C; the striping rate is 10 m / min, and the strip width is 12 mm.

Step 6: The composite strip after the above striping is punched to prepare an elastic electrical contact material of a desired size.

Step 7: Clean and package the above elastic electrical contact materials.

Embodiment 3

For example, a three-layer elastic electrical contact composite material as shown in FIG. 2 is prepared, one is 301 stainless steel, and the second is Cu: the elastic electrical contact composite material prepared is made of stainless steel/Cu/stainless steel three-layer composite material strip, in three layers. The thickness of the single side stainless steel layer in the composite strip is 20%-45% of the entire composite strip.

The first step: composite rolling of 301 stainless steel strip and Cu strip to prepare 301/Cu/301 three-layer composite strip, adopting cold rolling composite, the strip width is 400mm, the rolling deformation is 60%, compound The rate is 1.5m/min;

The second step: stainless steel / Cu / stainless steel three-layer composite strip for diffusion heat treatment, the temperature is 925 ° C, using continuous annealing, the rate is 1.5m / min, the atmosphere is H ₂ , the gas flow rate is 3m ³ / h;

The third step: the above-mentioned heat-treated composite material strip is subjected to four cycles (rolling→softening heat treatment), and the rolling deformation amount is 35% in each cold rolling step before the cold rolling finished product, and the softening heat treatment is adopted, and the temperature is 950 ° C. The rate is 1.3 m/min, the atmosphere is H ₂ , the gas flow rate is 3 m ³ /h, and the cold rolling deformation of the finished product is 40%.

The fourth step: the above-mentioned heat-treated composite material strip is subjected to tension correction, and the tensile elongation is controlled to be within 0.5%, preferably 0 to 0.3%, and the material strip thickness tolerance is ±0.01 mm;

Step 5: After the above-mentioned tensioned composite strip is cleaned in stages, it is divided into strips and washed at different temperatures. The first stage: adding environmentally friendly degreaser in clean water at a temperature of 40 ° C, using a soft brush The surface of the composite strip is cleaned to remove the grease on the surface of the composite strip; the second stage: the temperature is 40 ° C, the surface of the composite strip is cleaned in clean water, and the residual degreaser on the surface of the composite strip is removed. Drying, the temperature is 80 ° C; the striping rate is 10 m / min, and the strip width is 15 mm.

Step 6: The composite strip after the above striping is punched to prepare an elastic electrical contact material of a desired size.

Step 7: Clean and package the above elastic electrical contact materials.

Embodiment 4

For example, a three-layer elastic electrical contact composite material as shown in FIG. 2 is prepared, 1 is 301 stainless steel, and 2 is Cu:

The first step: composite rolling of 301 stainless steel strip and Cu strip to prepare 301/Cu/301 three-layer composite strip, using cold rolling composite, the strip width is 200mm, the rolling deformation is 50%, compound The rate is 4m/min;

The second step: stainless steel / Cu / stainless steel three-layer composite strip for diffusion heat treatment, the temperature is 950 ° C, using continuous annealing, the rate is 3m / min, the atmosphere is N ₂ , the gas flow rate is 3m ³ / h;

The third step: the above-mentioned heat-treated composite material strip is subjected to four cycles (rolling→softening heat treatment), and the rolling deformation amount is 15% in each cold rolling step before cold rolling, and the softening heat treatment is performed at a temperature of 900 ° C. The rate is 3 m/min, the atmosphere is H ₂ , the gas flow rate is 3 m ³ /h, and the cold rolling deformation of the finished product is 50%.

The fourth step: the above-mentioned heat-treated composite material strip is subjected to tension correction, and the tensile elongation is controlled to be within 0.5%, and the thickness tolerance of the material belt is ±0.01 mm;

Step 5: After the above-mentioned stretched composite material belt is cleaned in stages, it is divided into strips and washed at different temperatures:

The first stage: adding an environmentally friendly degreaser to the clean water at a temperature of 60 ° C, using a soft brush to clean the surface of the composite strip to remove the surface grease of the composite strip;

The second stage: the temperature is 60 ° C, the surface of the composite strip is cleaned in clean water to remove the residual degreaser on the surface of the composite strip;

The third stage: drying the strip, the temperature is 70 ° C; the striping rate is 10 m / min, and the strip width is 15 mm.

Step 6: The composite strip after the above striping is punched to prepare an elastic electrical contact material of a desired size.

Step 7: Clean and package the above elastic electrical contact materials.

The stainless steel double copper strips obtained in Examples 1 to 4 were tested for performance, and compared with the stainless steel complex Cu products and beryllium copper materials obtained by the prior method, and the results are shown in Table 1 and Table 2 below:

Table 1 Comparison of physical properties of different materials

Example	Material	tensile strength	Resistivity	Post-break elongation
Example 1	304/Cu	700MPa	4μΩ·cm	4%
Example 2	304/Cu	700MPa	4μΩ·cm	4%
Example 3	301/Cu/301	1225MPa	7.2μΩ·cm	3%
Example 4	301/Cu/301	1295MPa	7.2μΩ·cm	2%
Existing method	304/Cu	450MPa	-	15%
Beryllium copper	QBe1.7	637MPa	9.4μΩ·cm	3%

Table 2 Comparison of different temperature and hardness of different materials

Example

Material

Vickers hardness (25 ° C)

Vickers hardness (400 ° C)

Example 1	304/Cu	380HV	375HV
Example 2	304/Cu	380HV	380HV
Example 3	301/Cu/301	450HV	450HV
Example 4	301/Cu/301	500HV	495HV
Existing method	304/Cu	-	-
Beryllium copper	QBe1.7	280HV	180HV

It can be seen from the above embodiments that the present invention adopts a staged heat treatment and a plurality of (rolling→softening heat treatment) cycle treatment combination, and can prepare an environmentally-friendly electric contact elastic material with high strength, high elasticity and low electrical resistivity, and the process. Simple, low cost, no special requirements for equipment.

The above is a detailed description of the present invention in conjunction with the specific preferred embodiments, and the specific embodiments of the present invention are not limited thereto, and those skilled in the art to which the present invention pertains, without departing from the scope of the present invention. In the following, it is also possible to make a number of simple deductions or substitutions, which should be considered as belonging to the claims submitted by the present invention.

Claims (10)

1. A method for preparing an elastic electrical contact composite material, comprising: the following steps:

   The first step: composite rolling of stainless steel strip and Cu strip to prepare stainless steel/Cu two-layer or stainless steel/Cu/stainless steel three-layer composite strip;

   The second step: diffusion heat treatment of stainless steel/Cu two-layer or stainless steel/Cu/stainless steel three-layer composite strip;

   The third step: the above-mentioned heat-treated composite material strip is subjected to a plurality of rolling processes followed by softening heat treatment;

   The fourth step: the above-mentioned heat-treated composite material strip is subjected to tension correction;

   Step 5: After the above-mentioned stretched composite material strip is cleaned in stages, the strip is divided;

   Step 6: The composite strip after the above striping is punched to prepare an elastic electrical contact material of a desired size.
2. The method for preparing an elastic electrical contact composite material according to claim 1, wherein in the third step, the cyclic process of softening heat treatment after multiple rolling, that is, one cold rolling and one softening heat treatment are sequentially performed. Interval cycle treatment, the rolling deformation of each cold rolling process before the last cold rolling is 15% to 35%.
3. The method for preparing an elastic electrical contact composite according to claim 2, wherein in the third step, the softening heat treatment is continuous annealing, the temperature is 900 ° C to 1050 ° C, and the rate is 0.5 m / min to 3.0. m/min, the atmosphere is H ₂ or N ₂ , and the gas flow rate is ≥ ₂ m ³ /h. The softening heat treatment can restore the composite strip to a soft state and ensure the ductility of the composite strip during the rolling process.
4. The method for preparing an elastic electrical contact composite material according to claim 1, wherein in the fifth step, the stepwise cleaning brush is cleaned by different temperature division stages, and the stainless steel/Cu/stainless steel three-layer composite material belt is used. :

   The first stage: adding degreasing agent in the water, the temperature is 40 ° C ~ 60 ° C, the surface of the composite strip is cleaned with a soft brush to remove the surface grease of the composite strip;

   The second stage: the temperature is 40 ° C ~ 60 ° C, the surface of the composite strip is cleaned in clean water to remove the residual degreaser on the surface of the composite strip;

   The third stage: drying the strip, the temperature is 60 ° C ~ 80 ° C.
5. The method for preparing an elastic electrical contact composite material according to claim 1, wherein: in the fifth step, the stepwise cleaning is performed by using different temperature differential stages for the stainless steel/Cu two-layer composite material belt:

   The first stage: adding degreasing agent in the water, the temperature is 40 ° C ~ 60 ° C, the surface of the composite strip is cleaned with a soft brush to remove the surface grease of the composite strip;

   The second stage: the temperature is 40 ° C ~ 60 ° C, the surface of the composite strip is cleaned in clean water to remove the residual degreaser on the surface of the composite strip;

   The third stage: adding an environmentally-friendly protective agent to the water at room temperature to passivate the surface of the composite strip;

   The fourth stage: drying the strip, the temperature is 60 ° C ~ 80 ° C.
6. The method for preparing an elastic electrical contact composite material according to any one of claims 1 to 5, wherein in the first step, the composite rolling adopts cold rolling composite, and the width of the strip is from 100 mm to 650 mm. The deformation amount is 50% to 70%, and the recombination rate is 1.5 m/min to 4 m/min.
7. The method for preparing an elastic electrical contact composite according to any one of claims 1 to 5, wherein in the second step, the diffusion heat treatment has a temperature of 800 ° C to 1083 ° C, preferably 850 ° C to 950 °C, continuous annealing, the rate is 1m / min ~ 3m / min, the atmosphere is H ₂ or N ₂ , gas flow rate ≥ _2m ³ / h.
8. The method for preparing an elastic electrical contact composite according to any one of claims 1 to 5, wherein in the fourth step, the tensile elongation is controlled to be within 0.5%, preferably 0 to 0.3%, The tape thickness tolerance is ±0.01mm.
9. The method for preparing an elastic electrical contact composite according to any one of claims 1 to 5, wherein in the fifth step, the striping rate is 10 m/min to 30 m/min, and the strip width is 10 mm. 300mm.
10. An elastic electrical contact composite material prepared by the method according to any one of claims 1-9, wherein the elastic electrical contact composite material is made of stainless steel/Cu two-layer or stainless steel/Cu/stainless steel three-layer composite material strip. In the two-layer composite strip, the thickness of the stainless steel layer is 20-80% of the thickness of the entire composite strip; in the three-layer composite strip, the thickness of the single-sided stainless steel layer is 20%-45% of the entire composite strip.

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