High-strength conductive free-cutting elastic copper alloy, preparation method and application thereof

Abstract

The application belongs to the field of copper alloy materials, and discloses a high-strength conductive easy-cutting elastic copper alloy, which comprises the following components: Ni: 0.5wt%-3wt%, Pb: 0.1wt%-2wt%, P: 0.1wt%-0.3wt%, Si: 0.01wt%-0.5wt%, and the balance is Cu. The preparation method comprises the following steps: weighing pure copper, pure nickel, pure silicon, pure lead and copper-phosphorus intermediate alloy according to the mass ratio, melting in a heating furnace, then casting the alloy melt into an ingot, and then sequentially performing homogenization treatment, first cold deformation treatment, first aging treatment, second cold deformation treatment, second aging treatment, third cold deformation treatment and annealing treatment to obtain the high-strength conductive elastic copper alloy. The application adds Si element in the composition of the alloy, the addition of the Si element can accelerate the precipitation of Ni5P4 phase particles and inhibit the particle coarsening, so that the strength and performance of the copper alloy are more excellent.

Description

Technical Field

[0001] This invention belongs to the field of copper alloys, and particularly relates to a high-strength, conductive, free-machining elastic copper alloy, its preparation method, and its application. Background Technology

[0002] C19160 copper alloy is an alloy material with superior properties such as high corrosion resistance, tensile strength, yield strength, high electrical conductivity, and easy machinability. It is currently widely used to replace beryllium copper alloys with similar performance at a lower cost. Due to its excellent overall performance, easy machinability, electrical conductivity, and tensile strength, C19160 copper alloy is commonly used in electrical contacts, elastic elements, and connectors, and is generally applied in the production of electronic connector components.

[0003] The C19160 alloy is mainly composed of Ni: 0.80-1.20%, Pb: 0.80-1.20%, P: 0.15-0.30%, and the balance copper. It has excellent strength and electrical conductivity, as well as good machinability. Although this alloy has the above advantages, its overall performance needs to be improved, especially its stress relaxation performance. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to overcome the shortcomings of the prior art and provide a high-strength, conductive, free-machining elastic copper alloy with high strength, excellent conductivity, excellent stress relaxation performance and corrosion resistance, and a method for preparing the same.

[0005] To solve the above-mentioned technical problems, the technical solution proposed by this invention is as follows:

[0006] A high-strength, conductive, free-machining, elastic copper alloy, by mass percentage, comprises: Ni: 0.5wt%-3wt%, P: 0.1wt%-0.3wt%, Pb: 0.1wt%-2wt%, Si: 0.01wt%-0.5wt%, with the balance being Cu. The Si content cannot be too low, otherwise the improvement in stress relaxation performance will be insignificant; nor can it be too high, otherwise the alloy's electrical conductivity will be significantly reduced. Similarly, the Pb content cannot be too low, otherwise it will have little impact on the alloy's machinability; and the Pb content cannot be too high, otherwise the alloy's mechanical properties will deteriorate.

[0007] Preferably, in the above-mentioned high-strength, conductive, free-machining elastic copper alloy, the mass content of Si element is not higher than 0.2 wt%.

[0008] In the aforementioned high-strength, conductive, free-machining elastic copper alloy, preferably, the ratio of Ni content to the sum of P and Si content is Ni:(P+Si)=2-6, more preferably Ni:(P+Si)=2.5-6, and the ratio of Ni content to P content is Ni:P=3-10 to achieve a better precipitation strengthening effect. The ratio of Ni content to Si content is Ni:Si=10-30. The addition of trace amounts of Si has little effect on conductivity while hindering the coarsening of Ni5P4, Ni3P and other precipitates during stress relaxation, while the fine precipitates have a more significant effect on dislocation inhibition.

[0009] Preferably, the high-strength, conductive, free-machining elastic copper alloy has a conductivity of 50-75% IACS, a tensile strength of 600-710 MPa, and an elongation of 3-10%; and its stress relaxation resistance can reach 70%-85% after being loaded at 150℃ for 100 hours.

[0010] As a general inventive concept, the present invention also provides a method for preparing the above-mentioned high-strength, conductive, free-machining elastic copper alloy, comprising the following steps:

[0011] (1) Weigh pure copper, pure nickel, pure silicon, pure lead and copper-phosphorus master alloy according to the mass ratio, put them into a heating furnace to melt, and then cast the alloy melt into an ingot to obtain an ingot billet.

[0012] (2) The ingot obtained in step (1) is homogenized; the main purpose is to eliminate defects caused by casting.

[0013] (3) The ingot billet after homogenization treatment in step (2) is subjected to a first cold deformation treatment, a first aging treatment, a second cold deformation treatment, a second aging treatment, a third cold deformation treatment, and an annealing treatment in sequence to obtain the high-strength conductive elastic copper alloy. Multi-stage aging treatment can promote the full precipitation of precipitate particles and avoid the coarsening of precipitates, thereby increasing strength; that is, the multi-stage aging treatment used in this application can promote the precipitation of precipitates in the matrix, while avoiding the growth of precipitates, making precipitation strengthening more significant. At the same time, fine precipitates can effectively pin dislocations, improving the strength and stress relaxation resistance of the alloy. The main purpose of annealing treatment is to increase the density of Ni-P clusters and reduce internal stress with almost no impact on mechanical properties.

[0014] In the preferred preparation method described above, in step (1), the furnace temperature is first raised to 1500-1600℃ and inert gas is introduced into the furnace. Then, pure copper, pure nickel, and pure silicon are placed into the heating furnace, and the furnace melt temperature is controlled at 1600-1800℃. After the raw materials are completely melted, the furnace temperature is adjusted to 1300-1350℃, and then lead and copper-phosphorus intermediate alloys are added for smelting to form an alloy melt.

[0015] In the above preparation method, preferably, in step (2), the homogenization treatment temperature is 900-950℃ and the time is 2-4h.

[0016] In the above-mentioned preparation method, preferably, in step (3), the first cold deformation treatment is a cold rolling deformation treatment, which is carried out in multiple passes. The deformation amount of each pass is controlled at 10-20%, and the deformation strain rate is 0.5-10s. -1 The total deformation amount in the cold rolling deformation treatment is 60%-70%. In the first cold deformation treatment, a larger deformation amount is beneficial for the precipitation of precipitates.

[0017] In the above preparation method, preferably, in step (3), the temperature of the first aging treatment is 400-500℃ and the time is 0.5-10 h; the temperature of the second aging treatment is 350-450℃ and the time is 0.5-10 h.

[0018] In the above-mentioned preparation method, preferably, in step (3), the second cold deformation treatment is a room temperature cold deformation treatment, with a total deformation of 50-60% and a deformation strain rate of 0.5-10 s. -1 The third cold deformation treatment is a room temperature cold deformation treatment, with a total deformation of 50-60% and a deformation strain rate of 0.5-10 s. -1 .

[0019] In the above preparation method, preferably, in step (3), the annealing temperature is 200-300℃ and the time is 0.5-2h.

[0020] As a general inventive concept, the present invention also provides the application of the above-mentioned high-strength, conductive, free-machining elastic copper alloy or the high-strength, conductive, free-machining elastic copper alloy prepared by the above-mentioned preparation method in electrical contacts, elastic elements or connectors.

[0021] Compared with the prior art, the advantages of the present invention are as follows:

[0022] (1) The present invention adds Si element to the alloy composition. The addition of Si element can accelerate the precipitation of Ni5P4 phase particles and inhibit particle coarsening, making the copper alloy stronger and more powerful.

[0023] (2) The present invention promotes the precipitation of nano-scale Ni5P4 phase from the matrix through multi-level combined aging treatment, ensuring excellent mechanical properties and excellent electrical conductivity. At the same time, the smaller precipitated phase can improve the stress relaxation resistance of the alloy. Low-temperature annealing can promote Ni-P clusters.

[0024] (3) The addition of Si can effectively suppress the coarsening of Ni5P4 during long-term stress relaxation at 150℃, effectively hinder dislocation movement, and improve the stress relaxation resistance of the alloy.

[0025] (4) The high-strength conductive elastic copper alloy of the present invention has an electrical conductivity of 50%-75% IACS, a tensile strength of 600-710MPa, and an elongation of 3%-10%; after being loaded at 150℃ for 100h, its stress relaxation resistance can reach 70%-85%, and it can be used in electrical contacts, elastic elements or connectors. Attached Figure Description

[0026] Figure 1 This is the microstructure of the alloy in the homogenized state in Example 4 of the present invention;

[0027] Figure 2 The microstructure of the alloy after secondary cold deformation in Example 4 of this invention;

[0028] Figure 3 The fracture morphology of the alloy after three cold deformations in Example 4 of the present invention is shown. Detailed Implementation

[0029] To facilitate understanding of the present invention, the present invention will be described more fully and in detail below with reference to preferred embodiments, but the scope of protection of the present invention is not limited to the following specific embodiments.

[0030] Unless otherwise defined, all technical terms used herein have the same meaning as commonly understood by those skilled in the art. The technical terms used herein are for the purpose of describing particular embodiments only and are not intended to limit the scope of the invention.

[0031] Unless otherwise specified, all reagents and raw materials used in this invention are commercially available products or products that can be prepared by known methods.

[0032] Example 1:

[0033] The present invention discloses a high-strength, conductive, free-machining elastic copper alloy, which, by mass percentage, comprises: Ni: 1.2 wt%, Pb: 0.50 wt%, P: 0.15%, Si: 0.05 wt%, with the balance being Cu and other unavoidable impurities.

[0034] The preparation method of the high-strength, conductive, free-machining elastic copper alloy in this embodiment includes the following steps:

[0035] (1) First, raise the temperature inside the furnace to 1550℃, put pure copper, pure nickel and pure silicon into the heating furnace to melt, control the temperature of the melt inside the furnace to 1650℃, and after the raw materials are completely melted, adjust the temperature to 1300℃, then add pure lead and copper-phosphorus intermediate alloy for smelting, and after the smelting is uniform, an alloy melt is formed, and then the alloy melt is cast into an ingot to obtain an ingot billet.

[0036] (2) The ingot obtained in step (1) is placed in a furnace for annealing and homogenization treatment at a temperature of 900℃ for 4 hours.

[0037] (3) The ingot obtained after step (2) is subjected to the first cold deformation treatment. The cold rolling deformation amount of the cold deformation treatment is 70%, the deformation amount of each cold rolling is controlled at 10%, and the deformation strain rate is 10s. -1 .

[0038] (4) The board obtained after step (3) is subjected to the first aging treatment at a temperature of 450°C for 1 hour.

[0039] (5) The sheet obtained after step (4) is subjected to a second room temperature cold deformation treatment. The total deformation is 60%, the deformation per pass is 10%, and the deformation strain rate is 5s. -1 .

[0040] (6) The board obtained after step (5) is subjected to a second aging treatment. The temperature of the second aging treatment is 400℃ and the treatment time is 1 hour.

[0041] (7) The sheet obtained after step (6) is subjected to a third room temperature cold deformation treatment, with a total deformation of 60%, a deformation of 10% per pass, and a deformation strain rate of 5s. -1 .

[0042] (8) The plate obtained after step (7) is annealed at 200℃ for 1 h to obtain a high-strength, conductive, easy-to-cut elastic copper alloy.

[0043] Example 2:

[0044] A high-strength, conductive, free-machining elastic copper alloy of the present invention comprises, by mass percentage: Ni: 0.5wt%, Pb: 1.00wt%, P: 0.15%, Si: 0.05wt%, with the balance being Cu and other unavoidable impurities.

[0045] The preparation method of the high-strength, conductive, free-machining elastic copper alloy in this embodiment includes the following steps:

[0046] (1) First, raise the temperature inside the furnace to 1600℃, put pure copper, pure nickel and pure silicon into the heating furnace to melt, control the temperature of the melt inside the furnace to 1700℃, and after the raw materials are completely melted, adjust the temperature to 1300℃, then add pure lead and copper-phosphorus intermediate alloy for smelting, and after the smelting is uniform, an alloy melt is formed, and then the alloy melt is cast into an ingot to obtain an ingot billet.

[0047] (2) The ingot obtained in step (1) is placed in a furnace for annealing and homogenization treatment at a temperature of 900℃ for 4 hours.

[0048] (3) The ingot obtained after step (2) is subjected to the first cold deformation treatment. The cold deformation amount of the cold deformation treatment is 70%, the deformation amount per pass is 10%, and the deformation strain rate is 5s. -1 .

[0049] (4) The board obtained after step (3) is subjected to the first aging treatment at a temperature of 450°C for 1 hour.

[0050] (5) The sheet obtained after step (4) is subjected to a second room temperature cold deformation treatment, with a total deformation of 60%, a per-pass deformation of 10%, and a deformation strain rate of 5s. -1 .

[0051] (6) The board obtained after step (5) is subjected to a second aging treatment. The temperature of the second aging treatment is 400℃ and the treatment time is 1 hour.

[0052] (7) The sheet obtained after step (6) is subjected to a third cold deformation treatment. The total deformation is 60%, the deformation of each cold rolling pass is controlled at 10%, and the deformation strain rate is 10s. -1 .

[0053] (8) The plate obtained after step (7) is annealed at 200℃ for 1 h to obtain a high-strength, conductive, easy-to-cut elastic copper alloy.

[0054] Example 3:

[0055] The present invention discloses a high-strength, conductive, free-machining elastic copper alloy, which, by mass percentage, comprises: Ni: 1.00 wt%, Pb: 1.00 wt%, P: 0.15%, Si: 0.25 wt%, with the balance being Cu and other unavoidable impurities.

[0056] The preparation method of the high-strength, conductive, free-machining elastic copper alloy in this embodiment includes the following steps:

[0057] (1) First, raise the temperature inside the furnace to 1550℃, put pure copper, pure nickel and pure silicon into the heating furnace to melt, control the temperature of the melt inside the furnace to 1750℃, and after the raw materials are completely melted, adjust the temperature to 1350℃, then add pure lead and copper-phosphorus intermediate alloy for smelting, and after the smelting is uniform, an alloy melt is formed, and then the alloy melt is cast into an ingot to obtain an ingot billet.

[0058] (2) The ingot obtained in step (1) is placed in a furnace for annealing and homogenization treatment at a temperature of 900℃ for 4 hours.

[0059] (3) The ingot obtained after step (2) is subjected to the first cold deformation treatment. The cold deformation amount of the cold deformation treatment is 70%, the deformation amount per pass is 10%, and the deformation strain rate is 5s. -1 .

[0060] (4) The board obtained after step (3) is subjected to the first aging treatment at a temperature of 500℃ for 1 hour.

[0061] (5) The sheet obtained after step (4) is subjected to a second cold deformation treatment. The total deformation is 60%, the deformation of each cold rolling pass is controlled at 10%, and the deformation strain rate is 10s. -1 .

[0062] (6) The board obtained after step (5) is subjected to a second aging treatment. The temperature of the second aging treatment is 400℃ and the treatment time is 1 hour.

[0063] (7) The sheet obtained after step (6) is subjected to a third cold deformation treatment. The total deformation is 60%, the deformation of each cold rolling pass is controlled at 10%, and the deformation strain rate is 10s. -1 .

[0064] (8) The plate obtained after step (7) is annealed at 300℃ for 1 h to obtain a high-strength, conductive, easy-to-cut elastic copper alloy.

[0065] Example 4:

[0066] The present invention discloses a high-strength, conductive, free-machining elastic copper alloy, which, by mass percentage, comprises: Ni: 1.00 wt%, Pb: 1.00 wt%, P: 0.25%, Si: 0.10 wt%, with the balance being Cu and other unavoidable impurities.

[0067] The preparation method of the high-strength, conductive, free-machining elastic copper alloy in this embodiment includes the following steps:

[0068] (1) First, raise the temperature inside the furnace to 1550℃, put pure copper, pure nickel and pure silicon into the heating furnace to melt, control the temperature of the melt inside the furnace to 1800℃, and after the raw materials are completely melted, adjust the temperature to 1350℃, then add pure lead and copper-phosphorus intermediate alloy to melt, and after melting evenly, form an alloy melt, and then cast the alloy melt into an ingot to obtain an ingot billet.

[0069] (2) The ingot obtained in step (1) is placed in a furnace for annealing and homogenization treatment at a temperature of 900℃ for 4 hours. The microstructure of the homogenized alloy is as follows: Figure 1 As shown.

[0070] (3) The ingot obtained after step (2) is subjected to a first cold deformation treatment. The cold rolling deformation amount is 70%, the secondary deformation amount is 10%, and the deformation strain rate is 5s. -1 .

[0071] (4) The board obtained after step (3) is subjected to the first aging treatment at a temperature of 450°C for 1 hour.

[0072] (5) The sheet obtained after step (4) is subjected to a second cold deformation treatment. The total deformation is 60%, the secondary deformation is 10%, and the deformation strain rate is 5s. -1 The microstructure of secondary cold deformation, such as Figure 2 As shown.

[0073] (6) The board obtained after step (5) is subjected to a second aging treatment. The temperature of the second aging treatment is 400℃ and the treatment time is 1 hour.

[0074] (7) The sheet obtained after step (6) is subjected to a third cold deformation treatment. The total deformation is 60%, the deformation of each cold rolling pass is controlled at 10%, and the deformation strain rate is 10s. -1 The fracture morphology after three cold deformations is shown in Figure 3 As shown.

[0075] (8) The plate obtained after step (7) is annealed at 300℃ for 1 h to obtain a high-strength, conductive, easy-to-cut elastic copper alloy.

[0076] Comparative Example 1:

[0077] The copper alloy of this comparative example, by mass percentage, comprises: Ni: 1.20%, Pb: 0.50%, P: 0.35%, Si: 0.05%, with the remainder being copper and other unavoidable impurities. The preparation method of this copper alloy is the same as in Example 1.

[0078] Comparative Example 2:

[0079] The composition of the copper alloy in this comparative example, by mass percentage, includes: Ni: 0.50%; Pb: 1.00%; P: 0.15%; the remainder being copper and other unavoidable impurities. The preparation method of the copper alloy in this comparative example is the same as that in Example 2, except that silicon is not added in step (1), and the other steps are exactly the same as in Example 2.

[0080] Comparative Example 3:

[0081] The copper alloy of this comparative example, by mass percentage, comprises: Ni: 1.00%, Pb: 1.00%, P: 0.30%, Si: 0.25%; the remainder being copper and other unavoidable impurities. The preparation method of the copper alloy of this comparative example is the same as that of Example 3.

[0082] Comparative Example 4:

[0083] The composition of the copper alloy in this comparative example, by mass percentage, includes: Ni: 1.00%; Pb: 1.00%; P: 0.25%; Si: 0.10%; the remainder being copper and other unavoidable impurities. The difference between this comparative example and Example 4 lies in the aging temperature. In this comparative example, the first aging temperature is 550°C, and the second aging treatment temperature is 500°C. Other processes and parameters are the same as in Example 4.

[0084] The composition of the high-strength, conductive, free-machining elastic copper alloys of the above embodiments and comparative examples is shown in Table 1. The conductivity, Vickers hardness, tensile strength, elongation, stress relaxation resistance, and machinability of the embodiments and comparative examples were tested according to the national standards of the People's Republic of China (GB / T 32791-2016, GB / T 4340.1-2009, GB / T 228.1-2021, GB / T3956-2008, GB / T 10120-2013, GB / T 41509-2022), and the results are shown in Table 2.

[0085] Table 1. Elemental composition (%) of copper alloys in Examples 1-4 and Comparative Examples 1-4

[0086]

[0087] Table 2 Physical properties of copper alloys from Examples 1-4 and Comparative Examples 1-4

[0088]

[0089] Analysis of the data from the examples and comparative examples in Table 2 shows that, compared to Comparative Example 1, Example 1 exhibits a significant decrease in alloy conductivity due to the increased phosphorus content (exceeding 0.3%). In Example 2, the absence of silicon in Comparative Example 2 results in a decrease in alloy strength because silicon facilitates better precipitation of nickel-phosphorus compounds, inhibiting particle coarsening and leading to superior alloy performance. In Example 3, the slightly higher phosphorus content (Ni:(P+Si)=1.8) prevents the formation of nickel-phosphorus compounds, hindering precipitation strengthening and severely impacting alloy conductivity. In Example 4, the different aging treatment parameters result in significant performance differences compared to Comparative Example 4. The lower aging temperature in Example 4 leads to finer precipitated particles, resulting in a more pronounced strengthening effect, and the lower aging temperature also preserves more dislocation structures.

Claims

1. A method for preparing a high-strength, conductive, free-machining elastic copper alloy, characterized in that, The high-strength, conductive, free-machining, elastic copper alloy, by mass percentage, comprises: Ni: 0.5wt%-3wt%, Pb: 0.1wt%-2wt%, P: 0.1wt%-0.3wt%, Si: 0.01wt%-0.5wt%, with the balance being Cu. The ratio of Ni content to the sum of P and Si content is Ni:(P+Si) = 2.5-6, the ratio of Ni content to P content is Ni:P = 3-10, and the ratio of Ni content to Si content is Ni:Si = 10-30. Its preparation method includes the following steps: (1) Weigh pure copper, pure nickel, pure silicon, pure lead and copper-phosphorus master alloy according to the mass ratio, put them into a heating furnace to melt, and then cast the alloy melt into an ingot to obtain an ingot billet. (2) The ingot obtained in step (1) is homogenized; (3) The ingot billet after homogenization treatment in step (2) is subjected to the first cold deformation treatment, the first aging treatment, the second cold deformation treatment, the second aging treatment, the third cold deformation treatment, and the annealing treatment in sequence to obtain a high-strength, conductive, easy-to-cut elastic copper alloy. The temperature of the first aging treatment is 400-500℃ and the time is 0.5-10 h; the temperature of the second aging treatment is 350-450℃ and the time is 0.5-10 h.

2. The preparation method according to claim 1, characterized in that, In step (1), the furnace temperature is first raised to 1500-1600℃, and then pure copper, pure nickel and pure silicon are put into the heating furnace. The furnace melt temperature is controlled at 1600-1800℃. After the raw materials are completely melted, the furnace temperature is adjusted to 1300-1350℃, and then lead and copper-phosphorus intermediate alloys are added for smelting to form an alloy melt.

3. The preparation method according to claim 1, characterized in that, In step (2), the homogenization treatment temperature is 900-950℃ and the time is 2-4h.

4. The preparation method according to claim 1, characterized in that, In step (3), the first cold deformation treatment is a cold rolling deformation treatment, which is carried out in multiple passes. The deformation amount of each pass is controlled at 10-20%, and the deformation strain rate is 0.5-10s. -1 The total deformation amount of cold rolling deformation treatment is 60%-70%.

5. The preparation method according to claim 1, characterized in that, In step (3), the second cold deformation treatment is a room temperature cold deformation treatment, with a total deformation of 50-60% and a deformation strain rate of 0.5-10s. -1 The third cold deformation treatment is a room temperature cold deformation treatment, with a total deformation of 50-60% and a deformation strain rate of 0.5-10 s. -1 .

6. The preparation method according to claim 1, characterized in that, In step (3), the annealing temperature is 200-300℃ and the time is 0.5-2h.

7. The preparation method according to claim 1, characterized in that, The mass content of Si element in the high-strength, conductive, free-machining elastic copper alloy is no higher than 0.2 wt%.

8. The application of a high-strength, conductive, free-machining elastic copper alloy prepared by any one of claims 1 to 7 in electrical contacts, elastic elements, or connectors.

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