A method for preparing a CuCrNb alloy material by vacuum induction melting

Abstract

The application discloses a kind of preparation methods of vacuum induction smelting CuCrNb alloy material, the component of the CuCrNb alloy includes 0.8%~3.4%Cr, 0.7%~3.0%Nb and the balance is Cu by mass percentage;The preparation method comprises the following steps: S1, take oxygen-free copper rod, intermediate alloy Cr and Nb;S2, oxygen-free copper rod is placed in crucible into smelting furnace, pouring mold is also placed into smelting furnace, intermediate alloy is placed into the second charging box of smelting furnace;S3, vacuum is extracted from smelting furnace in turn with mechanical pump and Roots pump;S4, first smelt oxygen-free copper rod in crucible, then add intermediate alloy into crucible;S5, alloy liquid refined in crucible is poured into mold;S6, mold is removed after cooling and then demoulding.The CuCrNb alloy material prepared by the application has extremely small component deviation and more uniform metallographic structure;Compared with the traditional aluminothermic method, the preparation success rate is greatly improved, and the preparation process is shortened and the production efficiency is improved.

Description

Technical Field

[0001] This invention relates to the field of copper alloy preparation technology, specifically a method for preparing CuCrNb alloy materials by vacuum induction melting. Background Technology

[0002] CuCrNb is a highly conductive, high-strength, dispersion-strengthened copper alloy suitable for high-temperature, high-heat-flux applications, such as rocket engine components. The alloy matrix contains a large number of fine Cr2Nb precipitates, allowing it to maintain good mechanical properties even after prolonged exposure to temperatures up to 700°C, making it a viable alternative to highly conductive materials such as Cu-Cr and Cu-Ag-Zr.

[0003] The United States has successfully produced this alloy and applied it to rocket engine components, such as combustion chamber liners and nozzles. Currently, the domestic market lacks the capacity for mass production and supply, and foreign countries have imposed a technology embargo, preventing the import of this material. The main methods for preparing CuCrNb alloys include aluminothermic melting, suspension melting, and powder metallurgy. Aluminothermic melting easily forms Al and Li oxides and causes Cu burn-off, leading to significant compositional deviations and reduced yields. Suspension melting consumes a large amount of energy, resulting in high costs, and low-melting-point Cu is easily burned off during the melting process, leading to significant compositional deviations. Powder metallurgy requires the preparation of powder first, and for mainstream powder preparation methods such as plasma rotating electrode (PREP) and electrode induction melting gas atomization (EIGA), preparing qualified CuCrNb alloy ingots remains a prerequisite.

[0004] Therefore, developing a low-cost, high-efficiency, and low-composition-deviation smelting method to prepare CuCrNb alloy is the key to realizing the mass production and domestic production of this material. Summary of the Invention

[0005] The purpose of this invention is to provide a method for preparing CuCrNb alloy materials by vacuum induction melting, which can produce alloy materials with more uniform metallographic structure.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] A method for preparing CuCrNb alloy material by vacuum induction melting, wherein the composition of the CuCrNb alloy comprises, by mass percentage, 0.8%–3.4% Cr, 0.7%–3.0% Nb, and the balance being Cu;

[0008] The preparation method includes the following steps:

[0009] S1. Ingredients:

[0010] Weigh out the oxygen-free copper rod, intermediate alloy Cr and Nb according to the mass percentage of the composition, and set aside.

[0011] S2, Loading the furnace:

[0012] Place the oxygen-free copper rod weighed in step S1 into a crucible and then into a melting furnace. Place the casting mold into the melting furnace as well. Place the intermediate alloys Cr and Nb weighed in step S1 into the secondary charging box of the melting furnace and close the furnace lid.

[0013] S3, Vacuuming:

[0014] A mechanical pump is used to evacuate the furnace in step S2. When the vacuum pressure inside the furnace P ≤ 0.08 MPa, a Roots pump is used to continue evacuating the furnace.

[0015] S4, Smelting:

[0016] When step S3 evacuates the vacuum to make the vacuum degree P≤10Pa in the melting furnace, the melting furnace is turned on to melt the oxygen-free copper rod in the crucible. After the oxygen-free copper rod in the crucible is completely melted, Ar gas is introduced into the melting furnace, and the intermediate alloys Cr and Nb are added from the secondary feeding box to the crucible for melting together. The maximum melting power is controlled at 60kW~70kW.

[0017] S5, Casting:

[0018] The refined alloy liquid in the crucible in step S4 is poured into the casting mold.

[0019] S6, Out of the oven:

[0020] After the ingot cast in step S5 has solidified and cooled, the mold is removed from the melting furnace and allowed to air-cool for a period of time before demolding.

[0021] S7, Composite Melting:

[0022] The alloy block obtained in step S6 is forged, and the deformation is controlled to be 75% to 85% during forging.

[0023] The forged alloy block is crushed into particles with a diameter of 5-15 mm and then remelted according to the smelting process in steps S4-S6.

[0024] The alloy block obtained from the remelting is then subjected to secondary forging, with the deformation controlled at 85%–92% during the forging process.

[0025] The alloy block after secondary forging is annealed at a temperature of 380℃~550℃.

[0026] The annealed alloy block is then aged at 160℃~350℃ for 24h~48h to obtain the CuCrNb alloy product.

[0027] Preferably, the particle size of the intermediate alloy in step S1 needs to be less than 20mm, and the dirt and rust on the surface of the intermediate alloy need to be cleaned before use.

[0028] Preferably, the casting mold used in step S2 is a water-cooled copper mold, and the crucible material is calcium oxide.

[0029] Preferably, step S4, melting, specifically involves turning on the power supply of the melting furnace heating device when the vacuum pressure P in the melting furnace is less than or equal to 10 Pa, and slowly increasing the melting power from 10 to 15 kW / min to 60 kW and maintaining it thereafter.

[0030] Preferably, in step S4, after Cu is completely melted, the refining continues for 2 to 5 minutes; then the melting power of the melting furnace is slowly reduced from 10 to 15 kW / min to 30 kW, and Ar gas is introduced into the melting furnace. When the vacuum pressure inside the furnace rises to 0.08 MPa, the introduction of Ar gas into the melting furnace is stopped, the secondary feeding box is opened, and the intermediate alloy is added into the crucible.

[0031] Preferably, after adding the intermediate alloy in step S4, the melting power of the melting furnace is slowly increased to 60kW-70kW at 10-15kW / min. After there are no floating objects on the surface of the melt in the crucible, the refining continues for 5-10 minutes.

[0032] Note: This smelting process allows Cu, Cr, and Nb to fuse more uniformly.

[0033] Preferably, step S5 casting specifically involves reducing the melting power of the melting furnace to 30kW-40kW after refining, tilting the crucible and holding it for 0.5 minutes before starting casting, and then turning off the power to the heating device of the melting furnace after casting is completed.

[0034] Preferably, the casting time in step S5 is less than 1 minute. After the first casting is completed, the casting in the mold needs to be fed back to the mold for shrinkage, and the number of times the feeding is fed back is 1 to 3.

[0035] Note: Controlling the pouring time is crucial to prevent defects in the alloy ingot due to excessive pouring time. Feeding pouring is also necessary to avoid internal defects in the alloy ingot.

[0036] Preferably, the specific process of step S6 is to first cool the mold after casting in the melting furnace for 30-60 minutes, then take the mold out of the melting furnace, and after taking it out of the furnace, let the mold air cool for 60-90 minutes before demolding.

[0037] Note: Control the cooling rate of the ingot to avoid defects in the alloy ingot caused by excessive cooling temperature difference.

[0038] Compared with the prior art, the beneficial effects of the present invention are:

[0039] (1) The CuCrNb alloy material prepared by this invention has extremely small compositional deviation and more uniform metallographic structure;

[0040] (2) The CuCrNb alloy preparation method of the present invention has a significantly improved success rate compared with the traditional aluminothermic method, and also shortens the preparation process and improves production efficiency.

[0041] (3) The CuCrNb alloy preparation method of the present invention reduces the burning loss of low melting point metals and has lower process costs compared with the suspension melting method, which is conducive to large-scale mass production. Attached Figure Description

[0042] Figure 1 This is the CuCrNb ingot prepared according to the present invention;

[0043] Figure 2 This is a metallographic image of the CuCrNb alloy prepared according to the present invention. Detailed Implementation

[0044] The following is combined Figures 1-2 The present invention will be described in detail below.

[0045] Example 1:

[0046] A method for preparing CuCrNb alloy material by vacuum induction melting, wherein the composition of the CuCrNb alloy includes 3.4% Cr, 3.0% Nb and the balance Cu by mass percentage;

[0047] The preparation method includes the following steps:

[0048] S1. Ingredients:

[0049] Weigh out the oxygen-free copper rod, intermediate alloy Cr and Nb according to the mass percentage of the composition, and set aside.

[0050] The intermediate alloy has a particle size of 18-20mm, and the intermediate alloy needs to be cleaned of stains and rust.

[0051] S2, Loading the furnace:

[0052] Place the oxygen-free copper rod weighed in step S1 into a crucible and then into a melting furnace. Place the casting mold into the melting furnace as well. Place the intermediate alloys Cr and Nb weighed in step S1 into the secondary charging box of the melting furnace and close the furnace lid.

[0053] The casting mold is a water-cooled copper mold, and the crucible is made of calcium oxide.

[0054] S3, Vacuuming:

[0055] A mechanical pump is used to evacuate the furnace in step S2. When the vacuum pressure inside the furnace P = 0.08 MPa, a Roots pump is used to continue evacuating the furnace.

[0056] S4, Smelting:

[0057] When the vacuum pressure inside the melting furnace reaches P = 10 Pa in step S3, turn on the power of the melting furnace heating device and slowly increase the melting power from 10 kW / min to 60 kW and maintain it. After the oxygen-free copper rod in the crucible is completely melted, continue refining for 5 minutes. Then, slowly reduce the melting power of the melting furnace from 10 kW / min to 30 kW and charge Ar gas into the melting furnace. When the vacuum pressure inside the furnace rises to 0.08 MPa, stop charging the melting furnace with Ar gas and add the intermediate alloy from the secondary charging box into the crucible for melting together. Then, slowly increase the melting power of the melting furnace to 70 kW from the heating device at 10 kW / min. After there are no floating objects on the surface of the melt in the crucible, continue refining for 10 minutes.

[0058] S5, Casting:

[0059] After the alloy liquid in the crucible is refined in step S4, the melting power of the melting furnace is reduced to 40kW. The crucible is tilted and held for 0.5 minutes before casting begins. After casting is completed, the power supply of the heating device of the melting furnace is turned off.

[0060] The casting time should be controlled between 0.9 and 1 minute. After the first casting is completed, the casting in the mold needs to be fed back once.

[0061] S6, Out of the oven:

[0062] First, let the mold that has been cast cool in the melting furnace for 30 minutes, then take the mold out of the melting furnace. After taking it out of the furnace, let the mold air cool for 60 minutes before demolding.

[0063] S7, Composite Melting:

[0064] The alloy block obtained in step S6 is forged, and the deformation is controlled to be 85% during forging.

[0065] The forged alloy block is crushed into particles with a diameter of 15mm and then remelted according to the smelting process in steps S4 to S6.

[0066] The alloy block obtained from the remelting is then subjected to a second forging process, during which the deformation is controlled to be 92%.

[0067] The alloy block after secondary forging is annealed at a temperature of 550℃.

[0068] The annealed alloy block is then aged at 350℃ for 24 hours to obtain the CuCrNb alloy product.

[0069] Example 2:

[0070] A method for preparing CuCrNb alloy material by vacuum induction melting, wherein the composition of the CuCrNb alloy includes 2.1% Cr, 1.8% Nb and the balance Cu by mass percentage;

[0071] The preparation method includes the following steps:

[0072] S1. Ingredients:

[0073] Weigh out the oxygen-free copper rod, intermediate alloy Cr and Nb according to the mass percentage of the composition, and set aside.

[0074] The intermediate alloy has a particle size of 16-18mm, and the intermediate alloy needs to be cleaned of stains and rust.

[0075] S2, Loading the furnace:

[0076] Place the oxygen-free copper rod weighed in step S1 into a crucible and then into a melting furnace. Place the casting mold into the melting furnace as well. Place the intermediate alloys Cr and Nb weighed in step S1 into the secondary charging box of the melting furnace and close the furnace lid.

[0077] The casting mold is a water-cooled copper mold, and the crucible is made of calcium oxide.

[0078] S3, Vacuuming:

[0079] A mechanical pump is used to evacuate the furnace in step S2. When the vacuum pressure inside the furnace P = 0.07 MPa, a Roots pump is used to continue evacuating the furnace.

[0080] S4, Smelting:

[0081] When the vacuum pressure inside the melting furnace reaches P = 9 Pa in step S3, turn on the power of the melting furnace heating device and slowly increase the melting power from 15 kW / min to 60 kW and maintain it. After the oxygen-free copper rod in the crucible is completely melted, continue refining for 3.5 min. Then, slowly reduce the melting power of the melting furnace from 15 kW / min to 30 kW and charge Ar gas into the melting furnace. When the vacuum pressure inside the furnace reaches 0.08 MPa, stop charging the melting furnace with Ar gas and add the intermediate alloy from the secondary charging box into the crucible for melting together. Then, slowly increase the melting power of the melting furnace to 65 kW from 15 kW / min and continue refining for 7.5 min after there are no floating objects on the surface of the melt in the crucible.

[0082] S5, Casting:

[0083] After the alloy liquid in the crucible is refined in step S4, the melting power of the melting furnace is reduced to 35kW. The crucible is tilted and held for 0.5 minutes before casting begins. After casting is completed, the power supply of the heating device of the melting furnace is turned off.

[0084] The casting time should be controlled between 0.8 and 0.9 minutes. After the first casting is completed, the casting in the mold needs to be fed twice to compensate for shrinkage.

[0085] S6, Out of the oven:

[0086] First, let the mold that has been cast cool in the melting furnace for 45 minutes, then take the mold out of the melting furnace. After taking it out of the furnace, let the mold air cool for 75 minutes before demolding.

[0087] S7, Composite Melting:

[0088] The alloy block obtained in step S6 is forged, and the deformation is controlled to be 80% during the forging process.

[0089] The forged alloy block is crushed into particles with a diameter of 10mm and then remelted according to the smelting process in steps S4 to S6.

[0090] The alloy block obtained from the remelting is then subjected to a second forging process, during which the deformation is controlled to be 88%.

[0091] The alloy block after secondary forging is annealed at a temperature of 460℃.

[0092] The annealed alloy block is then aged at 260℃ for 36 hours to obtain the CuCrNb alloy product.

[0093] Example 3:

[0094] A method for preparing CuCrNb alloy material by vacuum induction melting, wherein the composition of the CuCrNb alloy comprises 0.8% Cr, 0.7% Nb and the balance Cu by mass percentage;

[0095] The preparation method includes the following steps:

[0096] S1. Ingredients:

[0097] Weigh out the oxygen-free copper rod, intermediate alloy Cr and Nb according to the mass percentage of the composition, and set aside.

[0098] The intermediate alloy has a particle size of 15-16mm, and the intermediate alloy needs to be cleaned of its surface stains and rust.

[0099] S2, Loading the furnace:

[0100] Place the oxygen-free copper rod weighed in step S1 into a crucible and then into a melting furnace. Place the casting mold into the melting furnace as well. Place the intermediate alloys Cr and Nb weighed in step S1 into the secondary charging box of the melting furnace and close the furnace lid.

[0101] The casting mold is a water-cooled copper mold, and the crucible is made of calcium oxide.

[0102] S3, Vacuuming:

[0103] A mechanical pump is used to evacuate the furnace in step S2. When the vacuum pressure inside the furnace P = 0.06 MPa, a Roots pump is used to continue evacuating the furnace.

[0104] S4, Smelting:

[0105] When the vacuum pressure inside the melting furnace reaches P = 8 Pa in step S3, turn on the power of the melting furnace heating device and slowly increase the melting power from 12 kW / min to 60 kW and maintain it. After the oxygen-free copper rod in the crucible is completely melted, continue refining for 2 minutes. Then, slowly reduce the melting power of the melting furnace from 12 kW / min to 30 kW and charge Ar gas into the melting furnace. When the vacuum pressure inside the furnace reaches 0.08 MPa, stop charging the melting furnace with Ar gas and add the intermediate alloy from the secondary charging box into the crucible for melting together. Then, slowly increase the melting power of the melting furnace to 60 kW from 12 kW / min. After there are no floating objects on the surface of the melt in the crucible, continue refining for 5 minutes.

[0106] S5, Casting:

[0107] After the alloy liquid in the crucible is refined in step S4, the melting power of the melting furnace is reduced to 30kW. The crucible is tilted and held for 0.5 minutes before casting begins. After casting is completed, the power supply of the heating device of the melting furnace is turned off.

[0108] The casting time should be controlled between 0.7 and 0.8 minutes. After the first casting is completed, the casting in the mold needs to be fed three times to compensate for shrinkage.

[0109] S6, Out of the oven:

[0110] First, let the mold that has been cast cool in the melting furnace for 60 minutes, then take the mold out of the melting furnace. After taking it out of the furnace, let the mold air cool for 90 minutes before demolding.

[0111] S7, Composite Melting:

[0112] The alloy block obtained in step S6 is forged, and the deformation is controlled to be 75% during forging.

[0113] The forged alloy block is crushed into particles with a diameter of 5mm and then remelted according to the smelting process in steps S4 to S6.

[0114] The alloy block obtained from the remelting is then subjected to a second forging process, during which the deformation is controlled to be 85%.

[0115] The alloy block after secondary forging is annealed at a temperature of 380℃.

[0116] The annealed alloy block is then aged at 160℃ for 48 hours to obtain the CuCrNb alloy product.

[0117] Example 4:

[0118] The difference from Example 1 is that the composition of the CuCrNb alloy, by mass percentage, includes 1.6% Cr, 1.5% Nb, and the balance being Cu;

[0119] Example 5:

[0120] The difference from Example 1 is that the composition of the CuCrNb alloy, by mass percentage, includes 0.8% Cr, 0.7% Nb, and the balance being Cu;

[0121] Comparative Example 1:

[0122] The difference from Example 1 is that the raw materials Cr, Nb and Cu are metals with a purity of 99.95%, and in step S4, oxygen-free copper rods, chromium blocks and niobium blocks are directly placed in the crucible for melting.

[0123] Ingredient Analysis:

[0124] The alloy ingots obtained in Examples 1, 4, 5 and Comparative Example 1 were subjected to compositional analysis, and the analysis results are shown in Table 1.

[0125] Table 1. Composition analysis of each ingot sample

[0126]

[0127] Analysis and comparison of the composition of various alloy ingots show that the CuCrNb alloy ingots prepared by the method of this invention have smaller deviations in composition and more uniform microstructure. Compared with traditional processes, the preparation method of this invention not only shortens the preparation process and reduces the preparation cost, but also improves production efficiency and preparation success rate, which is conducive to large-scale mass production.

Claims

1. A method for preparing CuCrNb alloy materials by vacuum induction melting, characterized in that, The composition of the CuCrNb alloy, by mass percentage, includes 0.8%–3.4% Cr, 0.7%–3.0% Nb, and the balance being Cu; The preparation method includes the following steps: S1. Ingredients: Weigh out the oxygen-free copper rod, intermediate alloy Cr and Nb according to the mass percentage of the composition, and set aside. S2, Loading the furnace: Place the oxygen-free copper rod weighed in step S1 into a crucible and then into a melting furnace. Place the casting mold into the melting furnace as well. Place the intermediate alloys Cr and Nb weighed in step S1 into the secondary charging box of the melting furnace and close the furnace lid. S3, Vacuuming: A mechanical pump is used to evacuate the furnace in step S2. When the vacuum pressure inside the furnace P ≤ 0.08 MPa, a Roots pump is used to continue evacuating the furnace. S4, Smelting: When step S3 evacuates the vacuum to make the vacuum degree P≤10Pa in the melting furnace, the melting furnace is turned on to melt the oxygen-free copper rod in the crucible. After the oxygen-free copper rod in the crucible is completely melted, Ar gas is introduced into the melting furnace, and the intermediate alloys Cr and Nb are added from the secondary feeding box to the crucible for melting together. The maximum melting power is controlled at 60kW~70kW. Specifically, when the vacuum pressure P in the melting furnace is less than or equal to 10 Pa, the power supply of the melting furnace heating device is turned on, and the melting power is slowly increased from 10 to 15 kW / min to 60 kW and maintained. After Cu is completely melted, continue refining for 2 to 5 minutes; then slowly reduce the melting power of the melting furnace from 10 to 15 kW / min to 30 kW, and introduce Ar gas into the melting furnace. When the vacuum pressure inside the furnace rises to 0.08 MPa, stop introducing Ar gas into the melting furnace, open the secondary feeding box, and add the intermediate alloy into the crucible. After adding the intermediate alloy, slowly increase the power of the heating device to 60kW-70kW at a melting power of 10-15kW / min. After there are no floating objects on the surface of the melt in the crucible, continue refining for 5-10 minutes. S5, Casting: The refined alloy liquid in the crucible in step S4 is poured into the casting mold. S6, Out of the oven: After the ingot cast in step S5 has solidified and cooled, the mold is removed from the melting furnace and allowed to air-cool for a period of time before demolding. S7, Composite Melting: The alloy block obtained in step S6 is forged, and the deformation is controlled to be 75% to 85% during forging. The forged alloy block is crushed into particles with a diameter of 5-15 mm and then remelted according to the smelting process in steps S4-S6. The alloy block obtained from the remelting is then subjected to secondary forging, with the deformation controlled at 85%–92% during the forging process. The alloy block after secondary forging is annealed at a temperature of 380℃~550℃. The annealed alloy block is then aged at 160℃~350℃ for 24h~48h to obtain the CuCrNb alloy product.

2. The method for preparing CuCrNb alloy material by vacuum induction melting according to claim 1, characterized in that: In step S1, the particle size of the intermediate alloy must be less than 20mm, and the surface of the intermediate alloy must be cleaned of dirt and rust before use.

3. The method for preparing CuCrNb alloy material by vacuum induction melting according to claim 1, characterized in that: The casting mold used in step S2 is a water-cooled copper mold, and the crucible is made of calcium oxide.

4. The method for preparing CuCrNb alloy material by vacuum induction melting according to claim 1, characterized in that: Step S5, casting, specifically involves reducing the melting power of the smelting furnace to 30kW-40kW after refining, tilting the crucible and holding it for 0.5 minutes before starting casting, and then turning off the power to the heating device of the smelting furnace after casting is completed.

5. The method for preparing CuCrNb alloy material by vacuum induction melting according to claim 1, characterized in that: Step S5: Casting time < 1 min. After the first casting is completed, the casting in the mold needs to be fed back to the mold. The feeding back should be done 1 to 3 times.

6. The method for preparing CuCrNb alloy material by vacuum induction melting according to claim 1, characterized in that: The specific process of step S6 is to first cool the mold that has been cast in the melting furnace for 30-60 minutes, then take the mold out of the melting furnace, and after taking it out of the furnace, let the mold air cool for 60-90 minutes before demolding.

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