A high-strength and high-conductivity copper-silver alloy strip and preparation method thereof

Abstract

The invention discloses a high-strength and high-conductivity copper-silver alloy strip and a preparation method thereof. The composition and weight percentage of the copper-silver alloy strip are: Ag 23-25%; the rest are Cu and inevitable impurities. The preparation method comprises the following steps: smelting and casting-hot rolling-quenching-milling-first cold rolling-first aging heat treatment-cleaning-second cold rolling-second aging heat treatment-cleaning-third cold rolling-third aging heat treatment-fourth cold rolling-plate shape correction, and the temperatures of the first, second and third aging heat treatments are 360-420°C, 320-380°C and 260-300°C respectively. The invention utilizes the ratio of alloy components and the composite strengthening mechanism of alloy materials and adopts the above preparation process to achieve the purpose of uniform organization and high strength and high conductivity. The prepared copper-silver alloy strip has a tensile strength of ≥960MPa and a conductivity of ≥77%, and can meet the requirements of special performance.

Description

Technical Field

[0001] The invention belongs to the technical field of copper-silver alloy strips, and in particular relates to a high-strength and high-conductivity copper-silver alloy strip and a preparation method thereof. Background Art

[0002] With the development of science and technology and industry, the requirements for conductor materials in many fields such as high-intensity magnetic field systems and lead frames are becoming higher and higher. Conductive materials are not only required to have excellent conductivity, but also must have high strength.

[0003] Different fields have different requirements for the mechanical properties and conductivity of conductive materials. For example, in pulsed strong magnetic fields, the conductive materials of the magnet system are generally required to have high strength to withstand the strong Lorentz force, and good electrical and thermal conductivity; the lead frame materials of high-end integrated circuits are generally required to have a strength higher than 700MPa and a conductivity greater than 70%IACS.

[0004] Although conventional copper and its alloys are still widely used as the main conductive materials in conventional industries, copper-based alloys prepared by conventional alloying methods have been difficult to meet some special requirements in modern science and industry. Therefore, it is necessary to develop new alloys and new process methods with better performance. Summary of the invention

[0005] In order to solve the above technical problems, the present invention provides a high-strength and high-conductivity copper-silver alloy strip and a preparation method thereof, which has excellent mechanical properties and electrical conductivity.

[0006] The technical solution adopted by the present invention is as follows:

[0007] A high-strength and high-conductivity copper-silver alloy strip, the composition and weight percentage of the high-strength and high-conductivity copper-silver alloy strip are: Ag 23-25%; the rest is Cu and unavoidable impurities; the tensile strength of the high-strength and high-conductivity copper-silver alloy strip is ≥960MPa, and the conductivity is ≥77%.

[0008] The present invention also provides a method for preparing the high-strength and high-conductivity copper-silver alloy strip, which comprises the following steps: smelting and casting - hot rolling - quenching - milling - first cold rolling - first aging heat treatment - cleaning - second cold rolling - second aging heat treatment - cleaning - third cold rolling - third aging heat treatment - fourth cold rolling - plate shape correction;

[0009] The temperature of the first aging heat treatment is 360-420°C;

[0010] The temperature of the second aging heat treatment is 320-380°C;

[0011] The temperature of the third aging heat treatment is 260-300°C.

[0012] In the smelting and casting step, the ingot is cast at 980-1050°C.

[0013] In the hot rolling step, the ingot is kept at 700-730° C. for 3-6 hours and then hot rolled.

[0014] The deformation amount of the first cold rolling is 60-80%; the deformation amount of the second cold rolling is 80-90%; the deformation amount of the third cold rolling is 60-80%; and the deformation amount of the fourth cold rolling is 15-40%.

[0015] The total deformation of the first cold rolling, the second cold rolling, the third cold rolling and the fourth cold rolling is 96-99%.

[0016] The holding time of the first aging heat treatment is 4-8h.

[0017] The holding time of the second aging heat treatment is 2-6h.

[0018] The holding time of the third aging heat treatment is 2-5h.

[0019] In the plate shape correction step, the elongation is 0.2-0.4% and the correction tension is 150-400N / mm 2 .

[0020] In the preparation method of the high-strength and high-conductivity copper-silver alloy strip provided by the present invention, in order to reduce the uneven composition of the ingot crystal and the organization state that deviates from the equilibrium, improve the alloy plasticity, and improve the processing performance and final use performance, the ingot is homogenized at 700-730°C for 3-6 hours. In order to improve the strength of the copper-silver alloy, a deformation of 96-99% is performed during cold rolling. The deformation before the first aging cannot exceed 80%, and the preferred deformation is 60-77%.

[0021] The present invention aims at the current special requirements for high strength and high conductivity of copper alloys, utilizes the ratio of alloy components and the composite strengthening mechanism of alloy materials, and adopts a process flow of smelting casting-hot rolling-quenching-milling-first cold rolling-first aging heat treatment-cleaning-second cold rolling-second aging heat treatment-cleaning-third cold rolling-third aging heat treatment-fourth cold rolling-plate shape correction to achieve the purpose of uniform organization and high strength and high conductivity, with a tensile strength of ≥960MPa and a conductivity of ≥77%. The copper-silver alloy strip provided by the present invention meets the requirements of special performance. DETAILED DESCRIPTION

[0022] The present invention is described in detail below with reference to the embodiments.

[0023] Example 1

[0024] A high-strength and high-conductivity copper-silver alloy strip has the following chemical composition and weight percentage: 24.3% Ag; the rest is Cu and inevitable impurities.

[0025] The method for preparing the high-strength and high-conductivity copper-silver alloy strip comprises the following steps: smelting and casting - hot rolling - quenching - milling - first cold rolling - first aging heat treatment - cleaning - second cold rolling - second aging heat treatment - cleaning - third cold rolling - third aging heat treatment - fourth cold rolling - plate shape correction, specifically:

[0026] 1) Using electrolytic copper with a purity of 99.9% and high-purity silver with a purity of 99.99% as raw materials, smelting in a vacuum medium-frequency induction furnace, casting ingots under protective atmosphere, the casting temperature is 990°C, and the ingots are milled;

[0027] 2) The milled ingot is subjected to homogenization heat treatment at 730°C for 4 hours, hot rolled to a thickness of 18 mm, and water cooled;

[0028] 3) The hot-rolled billet is milled to 15 mm;

[0029] 4) First cold rolling to 3.5mm thickness;

[0030] 5) Keep at 380℃ for 5h for the first aging treatment;

[0031] 6) After cleaning, cold rolling is performed for the second time to 0.5 mm;

[0032] 7) 360℃ for 4h for the second aging heat treatment;

[0033] 8) After cleaning, cold rolling is performed for the third time to a thickness of 0.15 mm;

[0034] 9) Heat treatment for the third time at 300℃ for 4h;

[0035] 10) Finally, the fourth cold rolling is performed to a finished product thickness of 0.10 mm;

[0036] 11) Cleaning and passivation;

[0037] 12) Plate shape correction: elongation 0.3%, correction tension 200N / mm 2 .

[0038] Example 2

[0039] A high-strength and high-conductivity copper-silver alloy strip has the following chemical composition and weight percentage: 23.8% Ag; the rest is Cu and inevitable impurities.

[0040] The method for preparing the high-strength and high-conductivity copper-silver alloy strip comprises the following steps: smelting and casting - hot rolling - quenching - milling - first cold rolling - first aging heat treatment - cleaning - second cold rolling - second aging heat treatment - cleaning - third cold rolling - third aging heat treatment - fourth cold rolling - plate shape correction, specifically:

[0041] 1) Using electrolytic copper with a purity of 99.9% and high-purity silver with a purity of 99.99% as raw materials, smelting in a vacuum medium-frequency induction furnace, casting ingots under protective atmosphere, the casting temperature is 1000°C, and the ingots are milled;

[0042] 2) The milled ingot is subjected to homogenization heat treatment at 720°C for 4 hours, hot rolled to a thickness of 18 mm, and water cooled;

[0043] 3) The hot-rolled billet is milled to 15 mm;

[0044] 4) First cold rolling to 5.0mm thickness;

[0045] 5) Keep at 400℃ for 4h for the first aging treatment;

[0046] 6) After cleaning, cold rolling is performed for the second time to 0.8 mm;

[0047] 7) 380℃ for 5h for the second aging heat treatment;

[0048] 8) After cleaning, cold rolling is performed for the third time to a thickness of 0.18 mm;

[0049] 9) Heat treatment for the third time at 300℃ for 5h;

[0050] 10) Finally, the fourth cold rolling is performed to a finished product thickness of 0.15 mm;

[0051] 11) Cleaning and passivation;

[0052] 12) Plate shape correction: elongation 0.2%, correction tension 250N / mm 2 .

[0053] Comparative Example 1

[0054] A copper-silver alloy strip has the following chemical composition and weight percentage: 24.3% Ag; the rest is Cu and inevitable impurities.

[0055] The method for preparing the copper-silver alloy strip comprises the following steps: smelting and casting - hot rolling - quenching - milling - first cold rolling - aging heat treatment - second cold rolling - plate shape correction, specifically:

[0056] 1) Using electrolytic copper with a purity of 99.9% and high-purity silver with a purity of 99.99% as raw materials, smelting in a vacuum medium-frequency induction furnace, casting ingots under protective atmosphere, the casting temperature is 990°C, and the ingots are milled;

[0057] 2) The milled ingot is subjected to homogenization heat treatment at 730°C for 4 hours, hot rolled to a thickness of 18 mm, and water cooled;

[0058] 3) The hot-rolled billet is milled to 15 mm;

[0059] 4) First cold rolling to 0.5mm thickness;

[0060] 5) aging treatment at 400℃ for 4h;

[0061] 6) After cleaning, cold rolling is performed for the second time to a finished product thickness of 0.10 mm;

[0062] 7) Cleaning and passivation;

[0063] 8) Plate shape correction: elongation 0.2%, correction tension 250N / mm 2 .

[0064] Comparative Example 2

[0065] A copper-silver alloy strip has the following chemical composition and weight percentage: 23.8% Ag; the rest is Cu and inevitable impurities.

[0066] The method for preparing the copper-silver alloy strip comprises the following steps: smelting and casting - hot rolling - quenching - milling - first cold rolling - aging heat treatment - second cold rolling - second aging treatment - plate shape correction, specifically:

[0067] 1) Using electrolytic copper with a purity of 99.9% and high-purity silver with a purity of 99.99% as raw materials, smelting in a vacuum medium-frequency induction furnace, casting ingots under protective atmosphere, the casting temperature is 1000°C, and the ingots are milled;

[0068] 2) The milled ingot is subjected to homogenization heat treatment at 720°C for 4 hours, hot rolled to a thickness of 18 mm, and water cooled;

[0069] 3) The hot-rolled billet is milled to 15 mm;

[0070] 4) First cold rolling to 1.0mm thickness;

[0071] 5) Keep at 400℃ for 5h for the first aging treatment;

[0072] 6) After cleaning, cold rolling is performed for the second time to a finished product thickness of 0.15 mm;

[0073] 7) Keep at 240℃ for 4h for the second aging treatment;

[0074] 8) Cleaning and passivation;

[0075] 9) Plate shape correction: elongation 0.4%, correction tension 150N / mm 2 .

[0076] The tensile strength and electrical conductivity of the copper-silver alloy strips produced in the above embodiments and comparative examples are shown in Table 1.

[0077] Table 1

[0078] Thickness mm Tensile strength MPa Electrical conductivity %IACS Example 1 0.10 981 78.2 Example 2 0.15 963 77.8 Comparative Example 1 0.10 903 80.3 Comparative Example 2 0.15 847 86.9

[0079] The detailed description of a high-strength and high-conductivity copper-silver alloy strip and a preparation method thereof with reference to the above-mentioned embodiments is illustrative rather than restrictive, and several embodiments can be listed according to the limited scope. Therefore, changes and modifications without departing from the overall concept of the present invention should fall within the scope of protection of the present invention.

Claims

1. A high-strength and high-conductivity copper-silver alloy strip, characterized in that: The composition and weight percentage of the high-strength and high-conductivity copper-silver alloy strip are: Ag 23-25%; the rest is Cu and inevitable impurities; the tensile strength of the high-strength and high-conductivity copper-silver alloy strip is ≥960MPa, and the conductivity is ≥77%.

2. The method for preparing the high-strength and high-conductivity copper-silver alloy strip according to claim 1, characterized in that: The preparation method comprises the following steps: smelting and casting - hot rolling - quenching - milling - first cold rolling - first aging heat treatment - cleaning - second cold rolling - second aging heat treatment - cleaning - third cold rolling - third aging heat treatment - fourth cold rolling - plate shape correction; The temperature of the first aging heat treatment is 360-420°C; The temperature of the second aging heat treatment is 320-380°C; The temperature of the third aging heat treatment is 260-300°C.

3. The preparation method according to claim 2, characterized in that: In the smelting and casting step, the ingot is cast at 980-1050°C.

4. The preparation method according to claim 2, characterized in that: In the hot rolling step, the ingot is kept at 700-730° C. for 3-6 hours and then hot rolled.

5. The preparation method according to claim 2, characterized in that: The deformation amount of the first cold rolling is 60-77%; the deformation amount of the second cold rolling is 80-90%; the deformation amount of the third cold rolling is 60-80%; The deformation of the fourth cold rolling is 15-40%.

6. The preparation method according to claim 2 or 5, characterized in that: The total deformation of the first cold rolling, the second cold rolling, the third cold rolling and the fourth cold rolling is 96-99%.

7. The preparation method according to claim 2, characterized in that: The holding time of the first aging heat treatment is 4-8h.

8. The preparation method according to claim 2, characterized in that: The holding time of the second aging heat treatment is 2-6h.

9. The preparation method according to claim 2, characterized in that: The holding time of the third aging heat treatment is 2-5h.

10. The preparation method according to claim 2, characterized in that: In the plate shape correction step, the elongation is 0.2-0.4% and the correction tension is 150-400N / mm 2 .