A high-strength copper-nickel-tin alloy material and preparation method thereof

Abstract

The present invention relates to the technical field of copper alloy materials, and discloses a method for preparing a high-strength copper-nickel-tin alloy material, comprising the following steps: S1, raw material preparation, S2, smelting and casting, S3, homogenization treatment, S4, forging processing, S5, solid solution quenching, S6, aging treatment; and also discloses the copper-nickel-tin alloy material prepared by the above preparation method. The present invention, by adding trace elements such as manganese and niobium to the copper-nickel-tin alloy, changes the internal structure of the crystal, refines the grains of the structure, further improves the hardness and tensile strength of the copper-nickel-tin alloy, and avoids the continuous precipitation of discontinuous precipitation in the grains of the alloy structure; adopts a forging process combining free forging and small deformation forging, and adopts a solid solution treatment process and an aging treatment process at the same time, so that the above elements are fully dissolved into the copper matrix, which greatly alleviates the internal stress generated during the forging process, and further improves the strength and hardness of the alloy material.

Description

Technical Field

[0001] The invention relates to the technical field of copper alloy materials, in particular to a high-strength copper-nickel-tin alloy material and a preparation method thereof. Background Art

[0002] With the rapid development of modern industry, the performance requirements for alloy materials are increasing. Among many alloy materials, copper-nickel-tin alloy has broad application prospects in electronics, aerospace, automobile manufacturing and other fields due to its good conductivity, corrosion resistance, and certain strength and hardness.

[0003] However, the traditional copper-nickel-tin alloy is gradually unable to meet the stringent requirements of some high-end application scenarios in terms of hardness and tensile strength. For example, in the manufacture of heat dissipation components of electronic equipment, alloy materials are required to have higher strength to withstand complex thermal and mechanical stresses, while the mechanical properties of existing copper-nickel-tin alloys are limited, which may cause deformation and damage of heat dissipation components during long-term use, affecting the stability and service life of electronic equipment.

[0004] In the aerospace field, the requirements for the materials of structural parts are more stringent. Not only do they need to have high strength and hardness, but they also need to maintain good performance stability in extreme environments. The grains of traditional copper-nickel-tin alloys are relatively coarse, and there is a problem of discontinuous precipitation inside, which makes it impossible to further improve the strength and hardness of the alloy, limiting its application in key aerospace components.

[0005] The automotive manufacturing industry is also facing similar challenges. Engine components, transmission systems, etc. require the use of high-strength alloy materials to improve the wear resistance and reliability of components and reduce energy consumption and maintenance costs. However, the performance bottleneck of existing copper-nickel-tin alloys has hindered their widespread application in these key parts. A new technical solution is urgently needed to break through these limitations and improve the comprehensive performance of copper-nickel-tin alloys to meet the evolving industrial needs.

[0006] Therefore, the development of a high-strength copper-nickel-tin alloy material and a preparation method thereof that can significantly improve hardness and tensile strength and optimize organizational structure has important practical significance and broad market prospects. Summary of the invention

[0007] The object of the present invention is to provide a high-strength copper-nickel-tin alloy material and a preparation method thereof, so as to solve the problems raised in the above-mentioned background technology.

[0008] To achieve the above object, the present invention provides the following technical solutions:

[0009] A method for preparing a high-strength copper-nickel-tin alloy material comprises the following steps:

[0010] S1. Raw material preparation

[0011] According to the mass percentage, 8-10wt% of nickel plate, 5-7wt% of tin block, 0-0.2wt% of manganese sheet, 0-0.4wt% of niobium sheet are weighed, and the remainder is copper plate and inevitable trace impurities; the purity of nickel is ≥99.9%, the purity of tin is ≥99.9%, the purity of manganese is ≥99.5%, the purity of niobium is ≥99.5%, and the purity of copper is ≥99.9%.

[0012] Put the weighed raw materials into the crucible of the vacuum induction melting furnace and evacuate the furnace until the pressure inside is lower than Pa, and then high-purity argon is filled in as a protective gas to prevent the metal from oxidizing during the smelting process.

[0013] S2. Melting and Casting

[0014] Heat the charge to 1200-1300℃ at a heating rate of 10-15℃ / min to fully melt the raw materials, and keep them at this temperature for 30-40min. Use electromagnetic stirring to ensure that the alloy components are evenly mixed. Then add the modified castable into the melting furnace and continue stirring for 15-20min to make it evenly dispersed in the alloy liquid.

[0015] The bottom pouring casting method is adopted to pour the alloy liquid which is evenly melted and added with modified casting agent into a casting mold preheated to 300-400℃. The casting mold is made of graphite material to ensure good demoulding performance and ingot surface quality, and an ingot with a diameter of 80mm is obtained.

[0016] S3. Homogenization

[0017] The ingot is placed in a resistance heating furnace, heated to 800°C at a heating rate of 5-8°C / min, and kept at this temperature for 8 hours to eliminate the uneven distribution of components in the ingot and promote the uniformity of the grain structure. After homogenization treatment, it is cooled to 600°C in the furnace, and then taken out and air-cooled to room temperature;

[0018] S4, Forging Process

[0019] The above ingot is forged by a combination of free forging and small deformation forging. After forging, the forging is air-cooled to room temperature, and then the surface is cleaned to remove oxide scale and other impurities. A combination of pickling and mechanical grinding can be used to make the surface roughness reach Ra0.8-Ra1.6μm;

[0020] S5, solution quenching

[0021] The cleaned forgings are placed in a salt bath furnace, and the salt bath medium is 50% +50% The mixed salt is heated to 820℃ at a heating rate of 10-12℃ / min and kept at this temperature for 1h to fully dissolve the elements into the matrix to form a supersaturated solid solution and relieve the internal stress generated during the forging process. After the solution treatment, the forging is quickly taken out of the salt bath furnace and quenched in hot water at 60-80℃. The quenching time is controlled at 3-5min to ensure a good solution effect and organizational morphology.

[0022] S6. Aging treatment

[0023] The alloy after solution quenching is placed in an air circulation oven for aging treatment at 200-500°C for 10-960 minutes. During the aging process, the temperature fluctuation in the oven is controlled within ±5°C to ensure the consistency of the aging effect;

[0024] After the aging treatment is completed, the furnace is cooled to room temperature to obtain the final copper-nickel-tin alloy material.

[0025] As a further solution of the present invention: the preparation method of the modified casting agent is: taking an appropriate amount of natural rubber latex, adding 3%-5% of the mass of nano-silicon dioxide, stirring at high speed for 30-40 minutes at 60-70° C., so that the nano-silicon dioxide is evenly dispersed in the natural rubber latex to obtain a mixed emulsion;

[0026] Slowly drop 10%-15% of acrylic acid monomer by mass into the mixed emulsion, and simultaneously drop an initiator, and perform emulsion polymerization at 70-80° C. for 2-3 hours to obtain a polymerization product.

[0027] The polymerized product was washed with deionized water for 3-5 times and then vacuum dried at 50-60° C. for 4-6 h to obtain a modified casting agent.

[0028] As a further solution of the present invention: the initiator is ammonium persulfate, and the amount of the initiator is 0.5%-1% of the mass of the acrylic acid monomer.

[0029] As a further solution of the present invention: free forging process: the initial forging temperature is controlled at 850-900°C, a large-tonnage hydraulic press is first used for upsetting operation, the upsetting ratio is controlled at 1.5-2, the pressing rate of each upsetting is controlled at 5-8mm / s, after upsetting, the steel is returned to the furnace and heated to the original forging temperature, and the upsetting is repeated 1-3 times to improve the internal structure uniformity and density of the ingot; then a drawing operation is performed.

[0030] As a further solution of the present invention: the drawing operation process is: the roughened blank is drawn along the axial direction, the deformation amount of each drawing is controlled at 20%-30%, the ratio of the feed amount to the single-side pressing amount during the drawing process is controlled at 0.5-0.8, the drawing speed is controlled at 3-5mm / s, and the blank is returned to the furnace for heating once after every 2-4 drawing operations to ensure that the blank temperature is within the appropriate forging range. After multiple drawing operations, the length of the blank reaches 1.2-1.5 times of the predetermined size.

[0031] As a further solution of the present invention: small deformation forging process: the free forged billet is heated again to 800-850°C, and a precision forging machine is used for small deformation forging. The forging frequency of the precision forging machine is set to 80-100 times / min, and the pressing amount each time is controlled at 2-3mm. Through multiple accumulations of small deformations, the cross-sectional size of the billet is gradually forged to 20mm×20mm. At the same time, the temperature during the forging process is strictly controlled to avoid overheating and overburning. The final forging temperature should be maintained above 600°C.

[0032] As a further solution of the present invention: the pickling method is: the pickling solution uses a 10-15% sulfuric acid solution, and the pickling time is controlled at 10-15 minutes; the mechanical polishing method is: rinse with clean water after pickling, and then polish with sandpaper.

[0033] The present invention also discloses a high-strength copper-nickel-tin alloy material, which is prepared by the above-mentioned preparation process:

[0034] The high-strength copper-nickel-tin alloy material comprises the following components in percentage by weight: 8-10wt% nickel plate, 5-7wt% tin block, 0-0.2wt% manganese sheet, 0-0.4wt% niobium sheet, and the remainder is copper plate and inevitable trace impurities.

[0035] The copper-nickel-tin alloy material has a diameter of 80 mm, a cross-sectional size of 20 mm×20 mm, a tensile strength of ≥850 MPa, and a Vickers hardness of ≥400 HV.

[0036] Compared with the prior art, the present invention has the following beneficial effects:

[0037] 1. The present invention adds trace elements such as manganese and niobium to the copper-nickel-tin alloy to change the internal structure of the crystal, refine the grains of the structure, further improve the hardness and tensile strength of the copper-nickel-tin alloy, and avoid the continuous precipitation of discontinuous precipitation in the grains of the alloy structure;

[0038] 2. The present invention adds a modified casting agent during the smelting and pouring process, adopts a forging process combining free forging and small deformation forging, and simultaneously adopts a solution treatment process and an aging treatment process, so that the above elements are fully dissolved into the copper matrix, which greatly alleviates the internal stress generated during the forging process and further improves the strength and hardness of the alloy material. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 The metallographic images in Example 1 of the present invention have a scale ratio of 1:50 um.

[0040] Figure 2 The metallographic images in Example 1 of the present invention have a scale ratio of 1:100 um.

[0041] Figure 3 The metallographic images in Example 2 of the present invention have a scale ratio of 1:50 um.

[0042] Figure 4 The metallographic images in Example 2 of the present invention have a scale ratio of 1:100 um.

[0043] Figure 5 The metallographic images in Example 3 of the present invention have a scale ratio of 1:50 um.

[0044] Figure 6 The metallographic images in Example 3 of the present invention have a scale ratio of 1:100 um.

[0045] Figure 7 Metallographic diagrams of alloy materials obtained after aging treatment at 350°C for different lengths of time.

[0046] Figure 8 The engineering stress-strain curves of the alloy material of the present invention are shown in FIG. 1 when aged at 350° C. for different times. DETAILED DESCRIPTION

[0047] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0048] Example 1

[0049] In an embodiment of the present invention, a method for preparing a high-strength copper-nickel-tin alloy material comprises the following steps:

[0050] S1. Raw material preparation

[0051] According to the mass percentage, 9wt% of nickel plate, 6wt% of tin block, 0.1wt% of manganese sheet, and 0.2wt% of niobium sheet are weighed, and the remainder is copper plate and inevitable trace impurities; the purity of nickel is ≥99.9%, the purity of tin is ≥99.9%, the purity of manganese is ≥99.5%, the purity of niobium is ≥99.5%, and the purity of copper is ≥99.9%.

[0052] Put the weighed raw materials into the crucible of the vacuum induction melting furnace and evacuate the furnace until the pressure inside is lower than Pa, and then high-purity argon is filled in as a protective gas to prevent the metal from oxidizing during the smelting process.

[0053] S2. Melting and Casting

[0054] Preparation of modified casting agent:

[0055] Take an appropriate amount of natural rubber latex, add 4% of its mass of nano-silicon dioxide, stir at high speed at 65°C for 35 minutes to evenly disperse the nano-silicon dioxide in the natural rubber latex to obtain a mixed emulsion.

[0056] To the mixed emulsion, 12.5% ​​by mass of acrylic acid monomer was slowly added dropwise, and at the same time, initiator ammonium persulfate (the amount of initiator was 0.75% by mass of acrylic acid monomer) was added dropwise, and emulsion polymerization was carried out at 75° C. for 2.5 hours to obtain a polymerization product.

[0057] The polymerized product was washed with deionized water for 4 times and then dried under vacuum at 55° C. for 5 h to obtain a modified casting agent.

[0058] The charge was heated to 1250°C at a heating rate of 12.5°C / min to fully melt the raw materials, and kept at this temperature for 35 minutes. Electromagnetic stirring was used to ensure uniform mixing of the alloy components. Then, the prepared modified casting agent was added to the melting furnace in an amount of 0.25% of the mass of the alloy liquid. Stirring was continued for 17.5 minutes to make it evenly dispersed in the alloy liquid.

[0059] The bottom pouring casting method is adopted to pour the alloy liquid which is evenly melted and added with modified casting agent into a casting mold preheated to 350°C. The casting mold is made of graphite to ensure good demoulding performance and ingot surface quality, and an ingot with a diameter of 80 mm is obtained.

[0060] S3. Homogenization

[0061] The ingot is placed in a resistance heating furnace, heated to 800°C at a heating rate of 5-8°C / min, and kept at this temperature for 8h to eliminate the uneven distribution of components in the ingot and promote the uniformity of the grain structure.

[0062] After homogenization, the product was cooled to 600°C in the furnace and then air-cooled to room temperature.

[0063] S4, Forging Process

[0064] Free forging stage:

[0065] The ingot after homogenization treatment is heated, and the initial forging temperature is controlled at 875°C.

[0066] First, a large-tonnage hydraulic press is used for upsetting operation. The upsetting ratio is controlled at 1.5-2, and the pressing rate of each upsetting is controlled at 5-8mm / s. After upsetting, the steel is returned to the furnace and heated to the original forging temperature. The upsetting is repeated twice to improve the internal structure uniformity and density of the ingot.

[0067] Then the drawing operation is carried out, and the upsetting billet is drawn axially. The deformation amount of each drawing is controlled at 25%, the ratio of the feed amount to the single-sided pressing amount during the drawing process is controlled at 0.65, and the drawing speed is controlled at 4mm / s. After every 3 drawing times, the billet is returned to the furnace for heating to ensure that the billet temperature is within the appropriate forging range. After multiple drawing operations, the length of the billet reaches 1.35 times of the predetermined size.

[0068] Small deformation forging stage:

[0069] The free forged billet is reheated to 825°C and forged with small deformation using a precision forging machine.

[0070] The forging frequency of the precision forging machine is set to 90 times / min, and the reduction amount each time is controlled at 2.5mm. Through multiple accumulations of small deformations, the cross-sectional size of the billet is gradually forged to 20mm×20mm. At the same time, the temperature during the forging process is strictly controlled to avoid overheating and overburning. The final forging temperature should be maintained above 600℃.

[0071] After forging, the forging is air-cooled to room temperature, and then the surface is cleaned to remove scale and other impurities. A combination of pickling and mechanical polishing can be used. The pickling solution uses 12.5% ​​sulfuric acid solution, and the pickling time is controlled at 12.5 minutes. After pickling, rinse with clean water and then polish with sandpaper to make the surface roughness reach Ra1.2μm.

[0072] S5, solution quenching

[0073] The cleaned forgings are placed in a salt bath furnace, and the salt bath medium is 50% +50% The mixed salt is heated to 820℃ at a heating rate of 11.5℃ / min and kept at this temperature for 1h to allow the elements to fully dissolve into the matrix to form a supersaturated solid solution and relieve the internal stress generated during the forging process.

[0074] After solution treatment, the forgings are quickly taken out of the salt bath furnace and placed in 70°C hot water for quenching. The quenching time is controlled within 4 minutes to ensure good solution effect and organizational morphology.

[0075] S6. Aging treatment

[0076] The alloy after solution quenching is placed in an air circulation oven and aged at 350°C for 720 hours to form a strengthened microstructure. The longest aging time is 16 hours. During the aging process, the temperature fluctuation in the oven is controlled within ±5°C to ensure the consistency of the aging effect.

[0077] After the aging treatment is completed, the furnace is cooled to room temperature to obtain the final copper alloy material.

[0078] Example 2

[0079] The difference between this embodiment and embodiment 1 is that in step S1, 8 wt% of nickel plate and 5 wt% of tin block are weighed according to mass percentage, and the remainder is copper plate and inevitable trace impurities.

[0080] Example 3

[0081] The difference between this embodiment and embodiment 1 is that in step S1, 10wt% of nickel plate, 7wt% of tin block, 0.2wt% of manganese sheet, 0.4wt% of niobium sheet are weighed according to mass percentage, and the remainder is copper plate and inevitable trace impurities.

[0082] Example 4

[0083] The difference between this embodiment and embodiment 1 is that in step S2, the modified casting agent is prepared as follows:

[0084] Take an appropriate amount of natural rubber latex, add 3% of its mass of nano-silicon dioxide, stir at high speed at 60°C for 30 minutes to evenly disperse the nano-silicon dioxide in the natural rubber latex to obtain a mixed emulsion.

[0085] Slowly add 10% by mass of acrylic acid monomer to the mixed emulsion, and simultaneously add initiator ammonium persulfate (the amount of initiator is 0.5% by mass of acrylic acid monomer) and carry out emulsion polymerization at 70° C. for 2 h to obtain a polymerization product.

[0086] The polymerized product was washed with deionized water for three times and then dried under vacuum at 50°C for 6 h to obtain a modified casting agent.

[0087] Heat the charge to 1200℃ at a heating rate of 10℃ / min to fully melt the raw materials, and keep it at this temperature for 30 minutes. Use electromagnetic stirring to ensure that the alloy components are evenly mixed. Then add the prepared modified casting agent into the melting furnace in an amount of 0.2% of the mass of the alloy liquid. Continue stirring for 15 minutes to make it evenly dispersed in the alloy liquid.

[0088] Example 5

[0089] The difference between this embodiment and embodiment 1 is that in step S2, the modified casting agent is prepared as follows:

[0090] Take an appropriate amount of natural rubber latex, add 5% of its mass of nano-silicon dioxide, stir at high speed at 70°C for 40 minutes to evenly disperse the nano-silicon dioxide in the natural rubber latex to obtain a mixed emulsion.

[0091] Slowly add 15% by mass of acrylic acid monomer to the mixed emulsion, and simultaneously add initiator ammonium persulfate (the amount of initiator is 1% by mass of acrylic acid monomer), and carry out emulsion polymerization at 80° C. for 3 h to obtain a polymerization product.

[0092] The polymerized product was washed with deionized water for 5 times and then dried under vacuum at 60° C. for 6 h to obtain a modified casting agent.

[0093] The charge was heated to 1300°C at a heating rate of 15°C / min to fully melt the raw materials, and kept at this temperature for 40 minutes. Electromagnetic stirring was used to ensure uniform mixing of the alloy components. Then, the prepared modified casting agent was added to the melting furnace in an amount of 0.3% of the mass of the alloy liquid. Stirring was continued for 20 minutes to uniformly disperse it in the alloy liquid.

[0094] Example 6

[0095] The difference between this embodiment and embodiment 1 is that in step S4, in the free forging stage:

[0096] The ingot after homogenization treatment is heated, and the initial forging temperature is controlled at 850°C.

[0097] First, a large-tonnage hydraulic press is used for upsetting operation. The upsetting ratio is controlled at 1.5, and the pressing rate of each upsetting is controlled at 5 mm / s. After upsetting, the steel is returned to the furnace and heated to the original forging temperature. The upsetting is repeated once to improve the internal structure uniformity and density of the ingot.

[0098] Then the drawing operation is carried out, and the upsetting billet is drawn axially. The deformation amount of each drawing is controlled at 20%, the ratio of the feed amount to the single-side pressing amount during the drawing process is controlled at 0.5, and the drawing speed is controlled at 3mm / s. After each two drawing times, the billet is returned to the furnace for heating to ensure that the billet temperature is within the appropriate forging range. After multiple drawing operations, the length of the billet reaches 1.2 times of the predetermined size.

[0099] Example 7

[0100] The difference between this embodiment and embodiment 1 is that in step S4, in the free forging stage:

[0101] The ingot after homogenization treatment is heated, and the initial forging temperature is controlled at 900°C.

[0102] First, a large-tonnage hydraulic press is used for upsetting operation. The upsetting ratio is controlled at 2, and the pressing rate of each upsetting is controlled at 8 mm / s. After upsetting, the steel is returned to the furnace and heated to the original forging temperature. The upsetting is repeated 3 times to improve the internal structure uniformity and density of the ingot.

[0103] Then the drawing operation is carried out, and the upsetting billet is drawn axially. The deformation amount of each drawing is controlled at 30%, the ratio of the feed amount to the single-sided pressing amount during the drawing process is controlled at 0.8, and the drawing speed is controlled at 5mm / s. After every 4 drawing times, the billet is returned to the furnace for heating to ensure that the billet temperature is within the appropriate forging range. After multiple drawing operations, the length of the billet reaches 1.5 times the predetermined size.

[0104] Example 8

[0105] The difference between this embodiment and embodiment 1 is that in step S4, during the small deformation forging stage:

[0106] The free forged billet is heated to 800°C again and subjected to small deformation forging using a precision forging machine.

[0107] The forging frequency of the precision forging machine is set to 80 times / min, and the reduction amount each time is controlled at 2mm. Through multiple accumulations of small deformations, the cross-sectional size of the billet is gradually forged to 20mm×20mm. At the same time, the temperature during the forging process is strictly controlled to avoid overheating and overburning. The final forging temperature should be maintained above 600℃.

[0108] After forging, the forging is air-cooled to room temperature, and then the surface is cleaned to remove scale and other impurities. A combination of pickling and mechanical polishing can be used. The pickling solution uses 10% sulfuric acid solution, and the pickling time is controlled within 10 minutes. After pickling, rinse with clean water and then polish with sandpaper to make the surface roughness reach Ra0.8μm.

[0109] Example 9

[0110] The difference between this embodiment and embodiment 1 is that in step S4, during the small deformation forging stage:

[0111] The free forged billet is reheated to 850°C and forged with small deformation using a precision forging machine.

[0112] The forging frequency of the precision forging machine is set to 100 times / min, and the reduction amount each time is controlled at 3mm. Through multiple accumulations of small deformations, the cross-sectional size of the billet is gradually forged to 20mm×20mm. At the same time, the temperature during the forging process is strictly controlled to avoid overheating and overburning. The final forging temperature should be maintained above 600℃.

[0113] After forging, the forging is air-cooled to room temperature, and then the surface is cleaned to remove scale and other impurities. A combination of pickling and mechanical polishing can be used. The pickling solution uses 15% sulfuric acid solution, and the pickling time is controlled within 15 minutes. After pickling, rinse with clean water and then polish with sandpaper to make the surface roughness reach Ra1.6μm.

[0114] Example 10

[0115] The difference between this embodiment and embodiment 1 is that, in step S6, the alloy after solution quenching is placed in an air circulation oven and subjected to aging treatment at 200°C for 720 minutes. During the aging process, the temperature fluctuation in the oven is controlled within ±5°C to ensure the consistency of the aging effect.

[0116] Embodiment 11

[0117] The difference between this embodiment and embodiment 1 is that, in step S6, the alloy after solution quenching is placed in an air circulation oven and subjected to aging treatment at 500°C for 720 minutes. During the aging process, the temperature fluctuation in the oven is controlled within ±5°C to ensure the consistency of the aging effect.

[0118] Example 12

[0119] The difference between this embodiment and embodiment 1 is that in step S6, an aging treatment is performed at 350° C. for 10 minutes.

[0120] Embodiment 13

[0121] The difference between this embodiment and embodiment 1 is that in step S6, an aging treatment is performed at 350° C. for 60 minutes.

[0122] Embodiment 14

[0123] The difference between this embodiment and embodiment 1 is that in step S6, an aging treatment is performed at 350° C. for 240 minutes.

[0124] Embodiment 15

[0125] The difference between this embodiment and embodiment 1 is that in step S6, an aging treatment is performed at 350° C. for 480 minutes.

[0126] Example 16

[0127] The difference between this embodiment and embodiment 1 is that in step S6, an aging treatment is performed at 350° C. for 960 minutes.

[0128] Comparative Example 1

[0129] The difference between this comparative example and Example 1 is that in step S2, no modified castable is added into the smelting furnace.

[0130] Comparative Example 2

[0131] The difference between this comparative example and Example 1 is that in step S4, the free forging method is not adopted.

[0132] Comparative Example 3

[0133] The difference between this comparative example and Example 1 is that in step S4, the small deformation forging method is not adopted.

[0134] Comparative Example 4

[0135] The difference between this comparative example and Example 1 is that in step S5, quenching is performed directly without performing solid solution treatment.

[0136] The copper-nickel-tin alloy material prepared in Example 1 was subjected to metallographic examination, and the following Figure 1 , 2 The scale ratios shown are 1:50um and 1:100um respectively. Figure 1 , 2 It can be observed that the copper-nickel-tin alloy material prepared by the method of the present invention has finer grains, higher density and better performance.

[0137] At the same time, for the preparation methods of the high-strength copper-nickel-tin alloy materials in the above-mentioned embodiments and comparative examples, the effects of the preparation methods of the present invention on the strength properties of the copper-nickel-tin alloy materials were tested respectively, as follows:

[0138] 1. The influence of different material ratios of raw materials on the strength of alloy materials is explored, and experimental comparisons are carried out with Examples 1-3. The results are shown in Table 1 below. At the same time, the copper-nickel-tin alloy materials prepared in Examples 2 and 3 are subjected to metallographic examination to obtain the metallographic diagrams of the corresponding materials, as shown in Table 1. Figure 3-Figure 6 shown.

[0139] Test samples Tensile strength (MPa) Hardness (HV) Example 1 933.44 444.02 Example 2 680.35 340.68 Example 3 852.56 410.42

[0140] Table 1

[0141] From Table 1 above, it can be concluded that different ratios of raw materials have a certain influence on the tensile strength and hardness of the final copper-nickel-tin alloy material, and by comparison, it can be concluded that the alloy material obtained in Example 1 has the highest strength and the best hardness. Figure 1-Figure 6 It can be seen that the alloy particle structure obtained in Example 1 has the finest grains and the highest density.

[0142] 2. Explore the effects of different process parameters of smelting casting, forging and aging treatment on the properties of copper-nickel-tin alloy materials.

[0143] Examples 1 and 4-11 were used for experimental comparison, and the results are shown in Table 2 below.

[0144] Test samples Tensile strength (MPa) Hardness (HV) Example 1 933.44 444.02 Example 4 902.65 408.89 Example 5 899.55 402.55 Example 6 904.35 405.63 Example 7 902.82 403.65 Example 8 903.66 404.08 Example 9 901.55 402.86 Example 10 856.25 408.22 Embodiment 11 865.78 411.58

[0145] Table 2

[0146] From Table 2 above, it can be concluded that different parameters of smelting casting, forging processing and aging treatment have a certain influence on the tensile strength and hardness of the final copper-nickel-tin alloy material, and by comparison, it can be concluded that the alloy material obtained in Example 1 has the highest strength and the best hardness, and the change of smelting casting and casting processing parameters has little effect on the performance of the alloy material, while the change of aging treatment parameters has a greater effect on the performance of the alloy material.

[0147] 3. Further explore the effect of aging treatment at 350°C for different lengths on the properties of copper-nickel-tin alloy materials.

[0148] Taking Examples 1, 12-16 as experimental comparison, the alloy materials prepared in the above examples were subjected to metallographic examination. The results are as follows: Figure 7 As shown; at the same time, the engineering stress-strain curve of the alloy material aged at 350℃ for different times is drawn, as shown Figure 8 shown.

[0149] from Figure 7 and Figure 8 It can be concluded that the alloy material prepared by aging treatment at 350°C for 720 minutes has better performance.

[0150] 4. Further explore the impact of omitting key process steps on the performance of copper-nickel-tin alloy materials.

[0151] Example 1 and Comparative Examples 1-4 were used for experimental comparison, and the results are shown in Table 3 below.

[0152] Test samples Tensile strength (MPa) Hardness (HV) Example 1 933.44 444.02 Comparative Example 1 720.82 358.52 Comparative Example 2 702.53 342.66 Comparative Example 3 715.32 352.63 Comparative Example 4 692.54 339.52

[0153] Table 3

[0154] It can be concluded from Table 3 above that after omitting the key processes (the process of adding modified casting agent, the forging process combining free forging and small deformation forging, and the solution treatment process), the performance of the final copper-nickel-tin alloy material is significantly reduced.

[0155] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above and that the present invention can be implemented in other specific forms without departing from the spirit or essential features of the present invention. Therefore, the embodiments should be considered exemplary and non-restrictive in all respects, and the scope of the present invention is defined by the appended claims rather than the above description, and it is intended that all changes falling within the meaning and scope of the equivalent elements of the claims be included in the present invention.

[0156] In addition, it should be understood that although the present specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

Claims

1. A method for preparing a high-strength copper-nickel-tin alloy material, characterized in that: The steps include: S1. Raw material preparation Weigh 8-10wt% of nickel plate, 5-7wt% of tin block, 0-0.2wt% of manganese sheet, 0-0.4wt% of niobium sheet according to mass percentage, and the remainder is copper plate and inevitable trace impurities; The weighed raw materials are placed in the crucible of the vacuum induction melting furnace and vacuumed until the pressure in the furnace is less than 10 -3 Pa, and then filled with high-purity argon as protective gas; S2. Melting and Casting Heat the charge to 1200-1300℃ at a heating rate of 10-15℃ / min to fully melt the raw materials, and keep them at this temperature for 30-40min. Use electromagnetic stirring to ensure that the alloy components are evenly mixed. Then add the modified castable into the melting furnace and continue stirring for 15-20min to make it evenly dispersed in the alloy liquid. The bottom pouring casting method is adopted to pour the alloy liquid which is evenly melted and added with modified casting agent into a casting mold preheated to 300-400°C. The casting mold is made of graphite to obtain an ingot with a diameter of 80mm. The preparation method of the modified casting agent is as follows: taking an appropriate amount of natural rubber latex, adding 3%-5% of the mass of nano-silicon dioxide, stirring at high speed for 30-40 minutes at 60-70° C., so that the nano-silicon dioxide is evenly dispersed in the natural rubber latex to obtain a mixed latex; Slowly drop 10%-15% of acrylic acid monomer by mass into the mixed emulsion, and at the same time drop an initiator, and perform emulsion polymerization at 70-80° C. for 2-3 hours to obtain a polymerization product; The polymerized product was washed with deionized water for 3-5 times, and then vacuum dried at 50-60° C. for 4-6 hours to obtain a modified casting agent; The initiator is ammonium persulfate, and the amount of the initiator is 0.5%-1% of the mass of the acrylic acid monomer; S3. Homogenization The ingot is placed in a resistance heating furnace, heated to 800°C at a heating rate of 5-8°C / min, and kept at this temperature for 8 hours. After homogenization, it is cooled to 600°C in the furnace, and then taken out and air-cooled to room temperature. S4. Forging The ingot is forged by a combination of free forging and small deformation forging. After forging, the forging is air-cooled to room temperature, and then the surface is cleaned to remove oxide scale and other impurities. A combination of pickling and mechanical grinding is used to make the surface roughness reach Ra0.8-Ra1.6μm; Free forging process: The initial forging temperature is controlled at 850-900℃. A large-tonnage hydraulic press is used for upsetting operation. The upsetting ratio is controlled at 1.5-2. The pressing rate of each upsetting is controlled at 5-8mm / s. After upsetting, the steel is returned to the furnace and heated to the original forging temperature. The upsetting is repeated 1-3 times. Then the drawing operation is performed. The drawing operation process is as follows: the roughened billet is drawn along the axial direction, the deformation amount of each drawing is controlled at 20%-30%, the ratio of the feed amount to the single-side pressing amount during the drawing process is controlled at 0.5-0.8, the drawing speed is controlled at 3-5mm / s, and the billet is returned to the furnace for heating once after each 2-4 drawing operations to ensure that the billet temperature is within the appropriate forging range. After multiple drawing operations, the length of the billet reaches 1.2-1.5 times of the predetermined size; Small deformation forging process: The free forged billet is reheated to 800-850℃, and the fine forging machine is used for small deformation forging. The forging frequency of the fine forging machine is set to 80-100 times / min, and the pressing amount each time is controlled at 2-3mm. Through multiple small deformation accumulations, the cross-sectional size of the billet is gradually forged to 20mm×20mm. At the same time, the temperature during the forging process is strictly controlled to avoid overheating and overburning. The final forging temperature should be kept above 600℃; S5, solution quenching The cleaned forgings are placed in a salt bath furnace. The salt bath medium is a mixed salt of 50% BaCl2 + 50% NaCl. The forgings are heated to 820°C at a heating rate of 10-12°C / min and kept at this temperature for 1 hour to allow the elements to fully dissolve into the matrix to form a supersaturated solid solution. After the solution treatment, the forgings are quickly taken out of the salt bath furnace and placed in hot water at 60-80°C for quenching. The quenching time is controlled at 3-5 minutes. S6. Aging treatment The alloy after solution quenching is placed in an air circulation oven for aging treatment at 200-500°C for 10-960 minutes. During the aging process, the temperature fluctuation in the oven is controlled within ±5°C to ensure the consistency of the aging effect; After the aging treatment is completed, the furnace is cooled to room temperature to obtain the final copper-nickel-tin alloy material.

2. The method for preparing a high-strength copper-nickel-tin alloy material according to claim 1, characterized in that: In step S2, the amount of modified casting agent added is 0.2%-0.3% of the mass of the alloy liquid.

3. The method for preparing a high-strength copper-nickel-tin alloy material according to claim 1, characterized in that: In step S4, the pickling method is: the pickling solution uses a 10-15% sulfuric acid solution, and the pickling time is controlled at 10-15 minutes; the mechanical grinding method is: rinse with clean water after pickling, and then grind with sandpaper.

4. A high-strength copper-nickel-tin alloy material prepared by the method for preparing a high-strength copper-nickel-tin alloy material as described in any one of claims 1 to 3.

5. A high-strength copper-nickel-tin alloy material according to claim 4, characterized in that: The copper-nickel-tin alloy material has a diameter of 80 mm, a cross-sectional size of 20 mm×20 mm, a tensile strength of ≥850 MPa, and a Vickers hardness of ≥400 HV.

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