An ultra-high strength copper-nickel-tin alloy and its preparation method

Abstract

The present invention provides a super high-strength copper-nickel-tin alloy and a preparation method thereof, belonging to the technical field of copper-nickel-tin. The present invention provides a super high-strength copper-nickel-tin alloy, which comprises the following chemical components by mass percentage: Ni: 14.8-15.5%, Sn: 7.8-8.5%, Fe≤0.5%, Mn: 0.2-0.25%, Zn≤0.5%, Mg≤0.05% and the balance of Cu. The results of the examples show that the super high-strength copper-nickel-tin alloy provided by the present invention has a tensile strength of 1350-1440 MPa, a yield strength of 1270-1340 MPa, and a conductivity of 8.2-8.6% IACS.

Description

Technical Field

[0001] The present invention relates to the technical field of copper-nickel-tin alloys, and particularly to a super-high-strength copper-nickel-tin alloy and a preparation method thereof. Background Art

[0002] Copper-nickel-tin alloy is a high-strength and high-elasticity conductive copper alloy, which has advantages such as high strength, good electrical conductivity stability, stress relaxation resistance, corrosion resistance, wear resistance, fatigue resistance, and small deformation. It can be stably used at 200-250°C and is an ideal high-performance and environmentally friendly material to replace beryllium bronze alloy. At present, copper-nickel-tin alloy is mainly used in the fields of manufacturing relays, potentiometers, switches, plug-in devices, lead frames, chemical and marine components, fasteners, elastic sensitive elements of optical instruments and instrument sensors, etc. Among them, with the continuous improvement of the integration degree of electronic components, the components are gradually miniaturized, ultrathin and functionalized, requiring the components to be smaller in size and lower in energy consumption within a limited space to improve the portability and functionality of mobile devices. Therefore, the copper-nickel-tin alloy has a thinner thickness, the thinnest reaching 0.03 mm, a higher strength, a tensile strength of more than 1300 MPa, and relatively good electrical conductivity is required. If the strength of the copper-nickel-tin alloy is low, the components manufactured are prone to fracture. At the same time, lamellar or cellular discontinuous precipitates will precipitate during the processing and heat treatment of the copper-nickel-tin alloy, resulting in poor consistency of the alloy strength and obvious decline in properties such as strength and plasticity. This will not only cause frequent strip breaks during the cold rolling process of the copper-nickel-tin alloy, but also stress low points will appear in the components, and fractures are extremely likely to occur during use, resulting in component failure.

[0003] Patent CN202211696774.3 discloses a super-high-strength and fracture-resistant copper-nickel-tin alloy foil and its manufacturing method. The copper-nickel-tin alloy foil includes the following chemical components by mass percentage: Ni + Co 14.50 - 16.50%, Sn 6.50 - 9.50%, Mn 0.10 - 0.50%, Co 0.10 - 0.50%, Nb 0.05 - 0.30%, Si 0.05 - 0.15%, Ti 0.05 - 0.15%, Zr 0.05 - 0.10%, B 0.005 - 0.02%, 0.15% ≤ Si + Ti + 0.5Nb ≤ 0.35%, 5 ≤ Zr / B ≤ 15, 0.05% ≤ Ce + Y ≤ 0.20%, and the balance is Cu and unavoidable impurities. The tensile strength of the alloy foil prepared by this invention is ≥1450 MPa, the yield strength is ≥1300 MPa, the elongation is 3.0 - 6.5%, and the conductivity (IACS) is 8.0 - 9.5%. The grains of the foil are fine and uniform, with a grain size of 8 - 15 μm. The strength, toughness, plasticity, conductivity, and fracture resistance of the foil are superior to those of C72900 alloy and C72950 alloy. Although a super-high-strength copper-nickel-tin alloy with a tensile strength ≥1450 MPa is obtained, it contains various types of micro-alloying elements and rare earth elements, and the atomic ratio between each element needs to be strictly controlled, which not only increases the production cost but also improves the difficulty in the preparation process, resulting in a high rejection rate of the copper-nickel-tin alloy.

[0004] Therefore, providing a copper-nickel-tin alloy with simple chemical composition and excellent mechanical properties has become an urgent technical problem to be solved in this field. Summary of the Invention

[0005] The purpose of the present invention is to provide a super-high-strength copper-nickel-tin alloy and its preparation method. The super-high-strength copper-nickel-tin alloy provided by the present invention has a simple chemical composition and excellent mechanical properties and electrical conductivity at the same time.

[0006] In order to achieve the above invention purpose, the present invention provides the following technical solutions:

[0007] The present invention provides a super-high-strength copper-nickel-tin alloy, which includes the following chemical components by mass percentage: Ni: 14.8 - 15.5%, Sn: 7.8 - 8.5%, Fe ≤ 0.5%, Mn: 0.2 - 0.25%, Zn ≤ 0.5%, Mg ≤ 0.05%, and the balance is Cu.

[0008] Preferably, it includes the following chemical components by mass percentage: Ni: 15.0 - 15.5%, Sn: 8.0 - 8.5%, Fe ≤ 0.5%, Mn: 0.2 - 0.25%, Zn ≤ 0.5%, Mg ≤ 0.05%, and the balance is Cu.

[0009] The present invention provides a method for preparing the above-mentioned ultra-high strength copper-nickel-tin alloy, comprising the following steps:

[0010] (1) Melting and horizontal continuous casting the alloy raw materials in sequence to obtain a billet;

[0011] (2) Conducting the first bell-jar annealing on the billet obtained in step (1) to obtain a first annealed strip;

[0012] (3) Conducting the first cold rolling on the first annealed strip obtained in step (2) to obtain a first cold-rolled strip;

[0013] (4) Conducting the first continuous annealing on the first cold-rolled strip obtained in step (3) to obtain a second annealed strip;

[0014] (5) Conducting the second cold rolling on the second annealed strip obtained in step (4) to obtain a second cold-rolled strip;

[0015] (6) Conducting the second bell-jar annealing on the second cold-rolled strip obtained in step (5) to obtain an ultra-high strength copper-nickel-tin alloy.

[0016] Preferably, the temperature of the horizontal continuous casting in step (1) is 1200 - 1230 °C.

[0017] Preferably, the temperature of the first bell-jar annealing in step (2) is 750 - 850 °C, and the heat preservation time of the first bell-jar annealing is 6 - 10 h.

[0018] Preferably, the atmosphere of the first bell-jar annealing in step (2) is a mixed atmosphere of hydrogen and nitrogen; the volume fraction of hydrogen in the mixed atmosphere is 45 - 65%, and the volume fraction of nitrogen in the mixed atmosphere is 35 - 55%.

[0019] Preferably, the total processing rate of the first cold rolling in step (3) is 85 - 95%.

[0020] Preferably, the temperature of the first continuous annealing in step (4) is 950 - 1050 °C, and the moving speed of the first continuous annealing is 1.0 - 2.5 m / min.

[0021] Preferably, the total processing rate of the second cold rolling in step (5) is 80 - 95%.

[0022] Preferably, the temperature of the second bell-jar annealing in step (6) is 350 - 400 °C, and the heat preservation time of the second bell-jar annealing is 6 - 10 h.

[0023] The present invention provides a super high-strength copper-nickel-tin alloy, which, by mass percentage, comprises the following chemical components: Ni: 14.8 - 15.5%, Sn: 7.8 - 8.5%, Fe ≤ 0.5%, Mn: 0.2 - 0.25%, Zn ≤ 0.5%, Mg ≤ 0.05% and the balance of Cu. The present invention takes copper element as the matrix element. Nickel and copper can form a continuous solid solution with unlimited solid solubility. By adding nickel element, the strength and corrosion resistance of the alloy can be improved, and at the same time, the gloss and color of the alloy can be adjusted. By adding a small amount of iron element and Zn element into the copper-nickel-tin alloy, the nucleation and growth of discontinuous precipitation phases in the alloy can be inhibited, the strength and plasticity of the alloy can be significantly improved, and by controlling the addition amounts of iron element and Zn element, the reduction of plasticity caused by excessive content thereof can be avoided. By adding Mn element into the copper-nickel-tin alloy, it has a deoxidizing effect, can refine the as-cast grain structure, inhibit grain boundary reaction and grain coarsening, and delay the precipitation of discontinuous precipitates during aging, thereby further improving the strength of the copper-nickel-tin alloy. By introducing a small amount of Mg element into the copper alloy, the hardness of the copper-nickel-tin alloy can be further improved. The results of the examples show that the tensile strength of the super high-strength copper-nickel-tin alloy provided by the present invention is 1350 - 1460 MPa, the yield strength is 1270 - 1360 MPa, and the conductivity is 8.2 - 8.6% IACS. Detailed implementation manners

[0024] The present invention provides a super high-strength copper-nickel-tin alloy, which, by mass percentage, comprises the following chemical components: Ni: 14.8 - 15.5%, Sn: 7.8 - 8.5%, Fe ≤ 0.5%, Mn: 0.2 - 0.25%, Zn ≤ 0.5%, Mg ≤ 0.05% and the balance of Cu.

[0025] By mass percentage, the super high-strength copper-nickel-tin alloy provided by the present invention comprises Ni: 14.8 - 15.5%, preferably 15.0 - 15.5%, more preferably 15.0 - 15.3%. In the present invention, nickel and copper can form a continuous solid solution with unlimited solid solubility. By adding nickel element, the strength and corrosion resistance of the alloy can be improved, and at the same time, the gloss and color of the alloy can be adjusted. When the content of nickel element is excessive, it will cause a large increase in the cost of the copper alloy. Therefore, its content is controlled within the range of 14.8 - 15.5%.

[0026] By mass percentage, the super high-strength copper-nickel-tin alloy provided by the present invention comprises Sn: 7.8 - 8.5%, preferably 8.0 - 8.5%, more preferably 8.0 - 8.2%. In the present invention, tin element is one of the matrix elements of the super high-strength copper-nickel-tin alloy. By controlling the content of tin element within the above range, the strength and conductivity of the copper-nickel-tin alloy can be further improved.

[0027] By mass percentage, the ultra-high strength copper-nickel-tin alloy provided by the present invention includes Fe ≤ 0.5%, preferably ≤ 0.4%, and more preferably 0.2 - 0.3%. By adding a small amount of iron element to the copper-nickel-tin alloy, the present invention can inhibit the nucleation and growth of discontinuous precipitation phases in the alloy, significantly improving the strength and plasticity of the alloy. However, when the content of iron is relatively high, it will reduce the plasticity of the alloy, resulting in difficult processing. Therefore, its content is controlled within the range of ≤ 0.5%.

[0028] By mass percentage, the ultra-high strength copper-nickel-tin alloy provided by the present invention includes Mn: 0.2 - 0.25%, preferably 0.2%. In the present invention, adding Mn element to the copper-nickel-tin alloy has a deoxidation effect, which can refine the as-cast grain structure, inhibit grain boundary reactions and grain coarsening, and delay the precipitation of discontinuous precipitates during aging, thereby further improving the strength of the copper-nickel-tin alloy.

[0029] By mass percentage, the ultra-high strength copper-nickel-tin alloy provided by the present invention includes Zn ≤ 0.5%, preferably ≤ 0.4%, and more preferably 0.3 - 0.4%. By adding a small amount of Zn element to the copper-nickel-tin alloy, the present invention can inhibit the nucleation and growth of discontinuous precipitation phases in the alloy, significantly improving the strength and plasticity of the alloy. However, when the content of Zn is relatively high, it will reduce the plasticity of the alloy, resulting in difficult processing. Therefore, its content is controlled within the range of ≤ 0.5%.

[0030] By mass percentage, the ultra-high strength copper-nickel-tin alloy provided by the present invention includes Mg ≤ 0.05%, preferably ≤ 0.04%, and more preferably 0.03 - 0.04%. By introducing a part of Mg element into the copper alloy, the present invention can improve the hardness of the copper-nickel-tin alloy; by strictly controlling the dosage of Mg element, the negative impact of Mg on the electrical conductivity of the copper-nickel-tin alloy can be avoided.

[0031] By mass percentage, the ultra-high strength copper-nickel-tin alloy provided by the present invention includes the balance of Cu. In the present invention, the copper element is the matrix element of the alloy.

[0032] The present invention uses copper as the matrix element. Nickel and copper can form a continuous solid solution with unlimited solid solubility. By adding nickel, the strength and corrosion resistance of the alloy can be improved, and at the same time, the gloss and color of the alloy can be adjusted. By adding a small amount of iron and Zn elements to the copper-nickel-tin alloy, the nucleation and growth of discontinuous precipitation phases in the alloy can be inhibited, the strength and plasticity of the alloy can be significantly improved, and by controlling the addition amounts of iron and Zn elements, the reduction of plasticity caused by excessive content can be avoided. Adding Mn element to the copper-nickel-tin alloy has a deoxidizing effect, which can refine the as-cast grain structure, inhibit grain boundary reactions and grain coarsening, and delay the precipitation of discontinuous precipitates during aging, thereby further improving the strength of the copper-nickel-tin alloy. By introducing a small amount of Mg element into the copper alloy, the hardness of the copper-nickel-tin alloy can be further improved.

[0033] The present invention provides a method for preparing the ultra-high strength copper-nickel-tin alloy described in the above technical solution, comprising the following steps:

[0034] (1) Melting and horizontally continuous casting the alloy raw materials in sequence to obtain a billet;

[0035] (2) Performing the first bell-type annealing on the billet obtained in step (1) to obtain a first annealed strip;

[0036] (3) Performing the first cold rolling on the first annealed strip obtained in step (2) to obtain a first cold-rolled strip;

[0037] (4) Performing the first continuous annealing on the first cold-rolled strip obtained in step (3) to obtain a second annealed strip;

[0038] (5) Performing the second cold rolling on the second annealed strip obtained in step (4) to obtain a second cold-rolled strip;

[0039] (6) Performing the second bell-type annealing on the second cold-rolled strip obtained in step (5) to obtain the ultra-high strength copper-nickel-tin alloy.

[0040] The present invention melts and horizontally continuous casts the alloy raw materials in sequence to obtain a billet.

[0041] In the present invention, the alloy raw materials preferably include pure nickel, electrolytic copper, pure iron, electrolytic manganese, copper-magnesium master alloy, pure zinc and recycled waste. In the present invention, the recycled waste preferably includes milling waste and rolling waste generated during the preparation of ultra-high strength copper-nickel-tin alloy; the amount of the recycled waste is preferably more than 50 wt% of the total amount of the alloy raw materials. In the present invention, the mass percentage content of Mg in the copper-magnesium master alloy is preferably 18-22%. The present invention uses recycled waste as alloy raw materials. Since the recycled waste is milling waste and rolling waste generated during the preparation of copper-nickel-tin alloy, its composition is controllable, which can not only ensure that the chemical composition of the copper-nickel-tin alloy meets the requirements, but also realize the reuse of waste and save a large amount of production costs.

[0042] The present invention has no special limitation on the specific source of the alloy raw materials, and commercially available products well-known to those skilled in the art or self-prepared ones can be used. The present invention has no special limitation on the specific amount of the alloy raw materials, as long as the chemical composition of the copper-nickel-tin alloy meets the requirements.

[0043] In the present invention, the melting is preferably carried out in an industrial frequency induction furnace. The present invention has no special limitation on the specific model of the industrial frequency induction furnace, and commercially available products well-known to those skilled in the art can be used.

[0044] The present invention has no special limitation on the process parameters of the melting, which can be determined according to the common technical knowledge of those skilled in the art.

[0045] After the melting is completed, the present invention preferably conducts a chemical composition test on the product of the melting. The present invention has no special limitation on the specific operation of the chemical composition test, and the methods well-known to those skilled in the art can be used. In the present invention, when the chemical composition of the product of the melting does not meet the chemical composition requirements of the ultra-high strength copper-nickel-tin alloy, the present invention preferably adjusts the chemical composition of the product of the melting; the adjustment method is preferably adding pure nickel, electrolytic copper, pure iron, electrolytic manganese, copper-magnesium master alloy or pure zinc. The present invention has no special limitation on the amount of pure nickel, electrolytic copper, pure iron, electrolytic manganese, copper-magnesium master alloy or pure zinc, as long as the chemical composition of the product of the melting meets the chemical composition requirements of the ultra-high strength copper-nickel-tin alloy. By testing the composition of the alloy melt, the present invention can ensure that the chemical composition of the copper-nickel-tin alloy does not deviate from the expectation.

[0046] In the present invention, the temperature of the horizontal continuous casting is preferably 1200-1230 °C, more preferably 1210-1220 °C; the drawing rate of the horizontal continuous casting is preferably 140-170 mm / min, more preferably 150-160 mm / min. The present invention has no special limitation on the drawing rate of the horizontal continuous casting, which can be determined according to the common technical knowledge of those skilled in the art.

[0047] After obtaining the slab, the present invention subjects the slab to a first bell-jar annealing to obtain a first annealed strip.

[0048] In the present invention, the temperature of the first bell-jar annealing is preferably 750 - 850 °C, more preferably 780 - 830 °C, and further preferably 800 °C; the holding time of the first bell-jar annealing is preferably 6 - 10 h, more preferably 7 - 9 h, and further preferably 8 h. In the present invention, the atmosphere of the first bell-jar annealing is preferably a mixed atmosphere of hydrogen and nitrogen; the volume fraction of hydrogen in the mixed atmosphere is preferably 45 - 65%, more preferably 50%; the volume fraction of nitrogen in the mixed atmosphere is preferably 35 - 55%, more preferably 50%. By subjecting the slab to bell-jar annealing treatment, the present invention can overcome the element segregation generated during the cooling of the slab and improve the uniformity of element distribution, thereby facilitating subsequent rolling treatment.

[0049] After the first bell-jar annealing is completed, the present invention preferably subjects the product after the first bell-jar annealing to sulfuric acid washing, water washing, and passivating agent washing in sequence. In the present invention, the mass concentration of the sulfuric acid solution used for sulfuric acid washing is preferably 16 - 19%, more preferably 17.5%; the passivating agent used for passivating agent washing is preferably an aqueous solution of benzotriazole; the mass concentration of the aqueous solution of benzotriazole is preferably 0.05 - 0.14%, more preferably 0.1%. The present invention has no special limitation on the specific number of times of sulfuric acid washing, water washing, and passivating agent washing, which can be determined according to the common technical knowledge of those skilled in the art. By sulfuric acid washing, the present invention can remove the oxide layer on the surface of the copper-nickel-tin alloy strip; by water washing, the residual sulfuric acid solution can be removed; by passivating agent washing, the surface of the copper-nickel-tin alloy strip can be passivated to avoid oxidation of the copper-nickel-tin alloy strip.

[0050] After obtaining the first annealed strip, the present invention subjects the first annealed strip to a first cold rolling to obtain a first cold-rolled strip.

[0051] In the present invention, the total processing rate of the first cold rolling is preferably 85 - 95%, more preferably 90%; the number of passes of the first cold rolling is preferably 9 - 14 passes, more preferably 11 - 13 passes; the single-pass deformation amount of the first cold rolling is preferably 5 - 8%, more preferably 6 - 7%. By the first cold rolling, on the one hand, the present invention can reduce the size of the slab, and on the other hand, it can break the coarse grains in the annealed strip, thereby eliminating tissue defects.

[0052] After the first cold rolling is completed, the present invention preferably mills the product of the first cold rolling; the thickness of the milling is preferably 1 - 2 mm / min. By milling, the present invention can remove the unevenly deformed parts, and at the same time remove the parts on both sides of the strip after the first cold rolling where oxygen elements are enriched, and can also reduce the influence of oxygen elements on the strip.

[0053] After obtaining the first cold-rolled strip, the present invention subjects the first cold-rolled strip to the first continuous annealing to obtain a second annealed strip.

[0054] In the present invention, the temperature of the first continuous annealing is preferably 950 - 1050 °C, more preferably 1000 - 1020 °C; the moving speed of the first continuous annealing is preferably 1.0 - 2.5 m / min, more preferably 1.5 - 2.0 m / min. In the present invention, the atmosphere of the first continuous annealing is preferably a mixed atmosphere of hydrogen and nitrogen; the volume fraction of hydrogen in the mixed atmosphere is preferably 2 - 5%, more preferably 5%; the volume fraction of nitrogen in the mixed atmosphere is preferably 95 - 98%, more preferably 95%. By the first continuous annealing, the present invention can improve the plasticity of the rolled copper-nickel-tin alloy strip, facilitating subsequent rolling, and on the other hand, can make the grain size more uniform.

[0055] After the first continuous annealing is completed, the present invention preferably sequentially performs sulfuric acid washing, water washing, and passivating agent washing on the product obtained from the first continuous annealing. In the present invention, the operations of sulfuric acid washing, water washing, and passivating agent washing, the reagents used, and their functions are the same as those described above for sulfuric acid washing, water washing, and passivating agent washing, and will not be elaborated here.

[0056] After obtaining the second annealed strip, the present invention subjects the second annealed strip to the second cold rolling to obtain a second cold-rolled strip.

[0057] In the present invention, the total processing rate of the second cold rolling is preferably 80 - 95%, more preferably 85 - 90%, and further preferably 90%; the number of passes of the second cold rolling is preferably 9 - 14 passes, more preferably 11 - 13 passes; the single-pass deformation of the second cold rolling is preferably 2 - 10%, more preferably 4 - 8%. By the second cold rolling, the present invention can make the size of the copper-nickel-tin alloy strip reach the size of the required product, and at the same time can improve the tissue uniformity of the copper-nickel-tin alloy and further improve its mechanical properties.

[0058] After obtaining the second cold-rolled strip, the present invention subjects the second cold-rolled strip to the second bell-type annealing to obtain a super-high-strength copper-nickel-tin alloy.

[0059] In the present invention, the temperature of the second bell annealing is preferably 350 to 400 °C, more preferably 350 to 380 °C; the holding time of the second bell annealing is preferably 6 to 10 h, more preferably 7 to 9 h, and further preferably 8 h; the atmosphere of the second bell annealing is preferably a mixed atmosphere of hydrogen and nitrogen; the volume fraction of hydrogen in the mixed atmosphere is preferably 45 to 65%, more preferably 50%; the volume fraction of nitrogen in the mixed atmosphere is preferably 35 to 55%, more preferably 50%. Through the second bell annealing, the present invention can make the grain size of the material more uniform and further improve the mechanical properties.

[0060] In the present invention, the billet is prepared by horizontal continuous casting, which can improve the quality of the billet. At the same time, the billet is in the shape of a plate, which is convenient for subsequent rolling and size control; by subjecting the billet to bell annealing treatment, the element segregation generated during the cooling process of the billet can be overcome, and the uniformity of element distribution can be improved, thus facilitating subsequent rolling treatment; through the first cold rolling, on the one hand, the size of the billet can be reduced, and on the other hand, the coarse grains in the annealed strip can be broken, thereby eliminating tissue defects; through the first continuous annealing, the plasticity of the rolled copper-nickel-tin alloy strip can be improved, facilitating subsequent rolling. On the other hand, the grain size can be made more uniform; through the second cold rolling, the size of the copper-nickel-tin alloy strip can reach the size of the required product, and at the same time, the tissue uniformity of the copper-nickel-tin alloy can be improved, further improving its mechanical properties; through the second bell annealing, the grain size of the material can be made more uniform and the mechanical properties can be further improved; by performing sulfuric acid washing, water washing and passivating agent washing multiple times after rolling and heat treatment, on the one hand, the oxide layer on the surface of the copper-nickel-tin alloy strip and the remaining sulfuric acid solution can be removed, and on the other hand, the surface of the copper-nickel-tin alloy strip can be passivated to avoid oxidation of the copper-nickel-tin alloy strip.

[0061] Next, the technical solutions in the present invention will be clearly and completely described in conjunction with the embodiments in the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in the present invention without creative efforts shall fall within the protection scope of the present invention.

[0062] Example 1

[0063] A super-high-strength copper-nickel-tin alloy, by mass percentage, consists of the following chemical components: Ni: 14.8%, Sn: 8.2%, Fe: 0.3%, Mn: 0.2%, Zn: 0.3%, Mg: 0.02% and the balance of Cu;

[0064] The preparation method of the super-high-strength copper-nickel-tin alloy is specifically the following steps:

[0065] (1) The alloy raw materials are sequentially melted and horizontally continuously cast to obtain a billet; the temperature of the horizontal continuous casting is 1200 °C, and the traction rate of the horizontal continuous casting is 140 mm / min;

[0066] (2) The billet obtained in the step (1) is subjected to the first bell-jar annealing, and then pickled with a sulfuric acid solution with a mass concentration of 17.5%, washed with tap water, and passivated with a benzotriazole aqueous solution with a mass concentration of 0.1% to obtain a first annealed strip; the temperature of the first bell-jar annealing is 800 °C, and the heat preservation time of the first bell-jar annealing is 8 h; the atmosphere of the first bell-jar annealing is a mixed atmosphere of hydrogen and nitrogen, the volume fraction of hydrogen in the mixed atmosphere is 50%, and the volume fraction of nitrogen in the mixed atmosphere is 50%;

[0067] (3) The first annealed strip obtained in the step (2) is subjected to the first cold rolling, and then face-milled to obtain a first cold-rolled strip; the total processing rate of the first cold rolling is 91%, the number of passes of the first cold rolling is 13 passes, and the single-pass deformation amount of the first cold rolling is 7%; the thickness of the face milling is 2 mm / surface;

[0068] (4) The first cold-rolled strip obtained in the step (3) is subjected to the first continuous annealing, and then pickled with a sulfuric acid solution with a mass concentration of 17.5%, washed with tap water, and passivated with a benzotriazole aqueous solution with a mass concentration of 0.1% to obtain a second annealed strip; the temperature of the first continuous annealing is 1000 °C, and the moving speed of the first continuous annealing is 2.0 m / min; the atmosphere of the first continuous annealing is a mixed atmosphere of hydrogen and nitrogen, the volume fraction of hydrogen in the mixed atmosphere is 5%, and the volume fraction of nitrogen in the mixed atmosphere is 95%;

[0069] (5) The second annealed strip obtained in the step (4) is subjected to the second cold rolling to obtain a second cold-rolled strip; the total processing rate of the second cold rolling is 91%, the number of passes of the second cold rolling is 13 passes, and the single-pass deformation amount of the second cold rolling is 7%;

[0070] (6) The second cold-rolled strip obtained in the step (5) is subjected to the second bell-jar annealing to obtain a super high-strength copper-nickel-tin alloy; the temperature of the second bell-jar annealing is 350 °C, and the heat preservation time of the second bell-jar annealing is 8 h; the atmosphere of the second bell-jar annealing is a mixed atmosphere of hydrogen and nitrogen, the volume fraction of hydrogen in the mixed atmosphere is 50%, and the volume fraction of nitrogen in the mixed atmosphere is 50%.

[0071] Example 2

[0072] A super high strength copper-nickel-tin alloy, by mass percentage, consists of the following chemical components: Ni: 15.2%, Sn: 8.5%, Fe: 0.2%, Mn: 0.2%, Zn: 0.3%, Mg: 0.03% and the balance of Cu;

[0073] The preparation method of the super high strength copper-nickel-tin alloy is the same as that of Example 1.

[0074] Example 3

[0075] A super high strength copper-nickel-tin alloy, by mass percentage, consists of the following chemical components: Ni: 15.0%, Sn: 8.2%, Fe: 0.2%, Mn: 0.25%, Zn: 0.4%, Mg: 0.03% and the balance of Cu;

[0076] The preparation method of the super high strength copper-nickel-tin alloy is the same as that of Example 1.

[0077] Example 4

[0078] A super high strength copper-nickel-tin alloy, by mass percentage, consists of the following chemical components: Ni: 15.5%, Sn: 7.9%, Fe: 0.2%, Mn: 0.25%, Zn: 0.1%, Mg: 0.01% and the balance of Cu;

[0079] The preparation method of the super high strength copper-nickel-tin alloy is the same as that of Example 1.

[0080] Example 5

[0081] A super high strength copper-nickel-tin alloy, by mass percentage, consists of the following chemical components: Ni: 15.3%, Sn: 8.4%, Fe: 0.3%, Mn: 0.2%, Zn: 0.2%, Mg: 0.03% and the balance of Cu;

[0082] The preparation method of the super high strength copper-nickel-tin alloy is the same as that of Example 1.

[0083] Comparative Example 1

[0084] A copper-nickel-tin alloy, by mass percentage, consists of the following chemical components: Ni: 15.0%, Sn: 8.2%, Mn: 0.2%, Mg: 0.03% and the balance of Cu;

[0085] The preparation method of the super high strength copper-nickel-tin alloy is the same as that of Example 1.

[0086] The properties of the copper-nickel-tin alloys provided in Examples 1 to 5 and Comparative Example 1 were tested, and the results are shown in Table 1:

[0087] Table 1 Properties of the copper-nickel-tin alloys provided in Examples 1 to 5 and Comparative Example 1

[0088]

[0089] Among them, the test method for tensile strength is: GB / T 34505-2017 Room Temperature Tensile Test Method;

[0090] The test method for elongation is: GB / T 22834505-2017 Room Temperature Tensile Test Method;

[0091] The test method for conductivity is: YS / T 478-2005 Eddy Current Testing Method for Conductivity;

[0092] The test method for salt spray test is: GB / T 10125 Corrosion Test in Artificial Atmospheres - Salt Spray Test - Neutral Salt Spray Test.

[0093] As can be seen from Table 1, the copper-nickel-tin alloy provided by the present invention only needs to add a small amount of micro-alloying elements, so that it not only has the characteristics of high tensile strength, yield strength and hardness, good ductility, but also has good conductivity and excellent corrosion resistance.

[0094] The above is only the preferred embodiment of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope of the present invention.

Claims

1. An ultra-high strength copper-nickel-tin alloy, composed of the following chemical components by mass percentage: Ni: 14.8~15.5%, Sn: 7.8~8.5%, Fe≤0.5%, Mn: 0.2~0.25%, Zn≤0.5%, Mg≤0.05% and the balance of Cu; The method for preparing the ultra-high strength copper-nickel-tin alloy comprises the following steps: (1) melting and horizontally continuously casting the alloy raw materials in sequence to obtain ingots; (2) subjecting the ingot obtained in step (1) to a first bell-jar annealing to obtain a first annealed sheet strip; the temperature of the first bell-jar annealing in step (2) is 750-850° C., and the holding time of the first bell-jar annealing is 6-10 h; (3) subjecting the first annealed sheet and strip obtained in step (2) to a first cold rolling to obtain a first cold rolled sheet and strip; (4) subjecting the first cold-rolled sheet obtained in step (3) to a first continuous annealing to obtain a second annealed sheet; wherein the temperature of the first continuous annealing in step (4) is 950-1050° C., and the moving speed of the first continuous annealing is 1.0-2.5 m / min; (5) cold rolling the second annealed sheet strip obtained in step (4) for a second time to obtain a second cold-rolled sheet strip; (6) The second cold-rolled sheet obtained in step (5) is subjected to a second bell-jar annealing to obtain an ultra-high strength copper-nickel-tin alloy; the temperature of the second bell-jar annealing in step (6) is 350-400° C., and the holding time of the second bell-jar annealing is 6-10 h.

2. The ultra-high strength copper-nickel-tin alloy according to claim 1, characterized in that: Calculated by mass percentage, it is composed of the following chemical components: Ni: 15.0~15.5%, Sn: 8.0~8.5%, Fe≤0.5%, Mn: 0.2~0.25%, Zn≤0.5%, Mg≤0.05% and the balance Cu.

3. The method for preparing the ultra-high strength copper-nickel-tin alloy according to any one of claims 1 to 2, comprising the following steps: (1) melting and horizontally continuously casting the alloy raw materials in sequence to obtain ingots; (2) subjecting the ingot obtained in step (1) to a first bell-jar annealing to obtain a first annealed sheet strip; the temperature of the first bell-jar annealing in step (2) is 750-850° C., and the holding time of the first bell-jar annealing is 6-10 h; (3) subjecting the first annealed sheet and strip obtained in step (2) to a first cold rolling to obtain a first cold rolled sheet and strip; (4) subjecting the first cold-rolled sheet obtained in step (3) to a first continuous annealing to obtain a second annealed sheet; wherein the temperature of the first continuous annealing in step (4) is 950-1050° C., and the moving speed of the first continuous annealing is 1.0-2.5 m / min; (5) cold rolling the second annealed sheet strip obtained in step (4) for a second time to obtain a second cold-rolled sheet strip; (6) The second cold-rolled sheet obtained in step (5) is subjected to a second bell-jar annealing to obtain an ultra-high strength copper-nickel-tin alloy; the temperature of the second bell-jar annealing in step (6) is 350-400° C., and the holding time of the second bell-jar annealing is 6-10 h.

4. The preparation method according to claim 3, characterized in that: The temperature of the horizontal continuous casting in step (1) is 1200-1230°C.

5. The preparation method according to claim 3, characterized in that: The atmosphere of the first bell-jar annealing in step (2) is a mixed atmosphere of hydrogen and nitrogen; the volume fraction of hydrogen in the mixed atmosphere is 45-65%, and the volume fraction of nitrogen in the mixed atmosphere is 35-55%.

6. The preparation method according to claim 3, characterized in that: The total processing rate of the first cold rolling in step (3) is 85-95%.

7. The preparation method according to claim 3, characterized in that: The total processing rate of the second cold rolling in step (5) is 80-95%.

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