Large-size copper-nickel alloy ingot and short-process production process thereof

Abstract

The application belongs to the technical field of non-ferrous metal smelting, and particularly discloses a large-size copper-nickel alloy ingot and a short-process production process thereof, which comprises the steps of batching and drying, furnace charging and preheating, smelting, multi-stage composite refining, on-furnace detection and composition adjustment, casting forming, and ingot cooling and post-processing. Through reasonable furnace charge ratio, stepwise temperature rising smelting strategy, multi-stage composite refining system, argon bottom blowing protection, and optimized casting process, the application significantly reduces the gas content and inclusion level in the melt, improves the composition uniformity and organizational density of the ingot, and meets the production requirements of large-size high-quality copper-nickel alloy ingots. The ingot prepared by the application has a diameter D of 360 mm or more and a height H of 2000 mm or more, and is suitable for high-quality production of large-size copper-nickel alloy ingots of grades such as BFe10-1-1 and BFe30-1-1.

Description

Technical Field

[0001] This invention belongs to the field of non-ferrous metal smelting technology, specifically relating to a large-size copper-nickel alloy ingot and its short-process production technology. Background Technology

[0002] Copper-nickel alloys, with copper as the base and nickel added to form a continuous solid solution, possess excellent resistance to seawater corrosion and good mechanical properties. They are widely used in marine engineering, shipbuilding, power equipment, and chemical pipelines. In particular, the BFe10-1-1 and BFe30-1-1 grades of copper-nickel alloys are known as "marine engineering alloys." With the development of large-scale and high-end marine equipment, the demand for large-size, high-quality copper-nickel alloy ingots is becoming increasingly urgent.

[0003] Existing copper-nickel alloy smelting technology has the following prominent problems in the production of large-size ingots: (1) The gas content is difficult to control.

[0004] (2) The problem of inclusions is prominent.

[0005] (3) Poor uniformity of alloying elements.

[0006] (4) Low casting efficiency and low yield.

[0007] Therefore, developing an efficient smelting method suitable for large-size copper-nickel alloys, effectively reducing gas content, minimizing inclusions, and improving compositional uniformity, is a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0008] The purpose of this invention is to overcome the aforementioned shortcomings in the prior art and provide a large-size copper-nickel alloy ingot and its short-process production technology. This invention significantly reduces the gas content and inclusion level in the melt through a reasonable charge ratio, a stepped heating melting strategy, a multi-stage composite refining system, argon bottom purging protection, and an optimized casting process. This improves the compositional uniformity and microstructure density of the ingot, meeting the production requirements of large-size, high-quality copper-nickel alloy ingots.

[0009] To achieve the above technical objectives, the technical solution adopted in the embodiments of the present invention is as follows: In a first aspect, embodiments of the present invention provide a short-process production technology for large-size copper-nickel alloy ingots, comprising the following steps: 1) Batching and drying: Batching is carried out in accordance with GB / T 5231 standard according to the chemical composition of the target grade copper-nickel alloy. After the batching is completed, the raw materials are placed in a drying oven and dried at 150-250℃ for 2-4 hours. (2) Loading and preheating: The dried raw materials are loaded into the induction melting furnace in the order of "refractory metals first, low melting point metals last". The raw materials are preheated at a temperature of 400-600℃ for 1-2 hours. (3) The preheated raw materials are smelted by step heating. During the smelting process, high-purity argon is continuously blown into the melt through the permeable bricks set at the bottom of the induction melting furnace. The argon flow rate is controlled at 10-30 L / min and the argon pressure is controlled at 0.1-0.3 MPa. Step heating smelting avoids the long-term oxidation of copper at high temperature. Argon is blown from the bottom throughout the process to isolate the melt from the air and actively exhaust the air from the source. (4) Multi-stage compound refining: After the melt temperature in step (3) reaches the refining temperature range, multi-stage compound refining is carried out. (5) Pre-furnace testing and composition adjustment: After the final deoxidation and refining is completed, samples are taken and the composition is analyzed on a spectrometer. When the test results deviate from the target composition, the corresponding intermediate alloy is added to adjust the composition until it is qualified. (6) Casting: The copper-nickel alloy melt that has passed the composition test is introduced into the crystallizer that has been preheated to 150-300℃ through the trough and cast using the vertical semi-continuous casting method. The casting temperature is controlled at 1430-1470℃. (7) Ingot cooling and post-treatment: During the casting process, the ingot is cooled in a zoned manner. After cooling, the surface is cleaned and defects are inspected to obtain large-size copper-nickel alloy ingots.

[0010] Furthermore, in step (3), the stepped heating smelting includes the following steps: (3.1) First heating stage: The furnace temperature is raised to 1250-1280℃ at a heating rate of 5-15℃ / min and held for 20-40min; (3.2) Second heating stage: Continue to raise the furnace temperature to 1300-1350℃ and hold for 30-60 min; (3.3) Third heating stage: Raise the furnace temperature to 1370-1450℃ and keep it warm for 5-15 minutes.

[0011] Further, in step (3), the purity of the argon gas is ≥99.99%, the pore size of the permeable brick is 0.5-2.0mm, and the number of permeable bricks is uniformly set to 2-8 according to the furnace bottom area.

[0012] Furthermore, in step (4), the multi-stage compound refining includes the following steps: (4.1) Multiple slag removal: Remove the slag floating on the liquid surface, let it stand for 10-20 minutes, and then perform the slag removal operation again after new slag floats to the surface. Repeat the slag removal operation 2-4 times until the liquid surface is smooth and there is no obvious slag. (4.2) Final deoxidation refining: 10-15 minutes before casting, add a final deoxidizer to the melt for final deoxidation treatment. The amount added is 0.03%-0.08% of the total melt volume.

[0013] Multi-stage compound refining combines multiple slag removal and final deoxidation, significantly reducing inclusions and gas content; Furthermore, the final deoxidizer is a copper-magnesium alloy, wherein the mass percentage of magnesium in the copper-magnesium alloy is 8%-15%.

[0014] Furthermore, in step (6), the crystallizer is made of pure copper and has a graphite coating with a thickness of 2-3 mm on its surface.

[0015] Furthermore, in step (7), the diameter D of the finished copper-nickel alloy ingot is ≥360 mm and the height H is ≥2000 mm.

[0016] Furthermore, in step (7), the upper part of the ingot is insulated to slow down the cooling rate, while the lower part is cooled by forced water cooling. The dividing point between the upper insulation and the lower cooling is 1 / 3 to 1 / 2 of the ingot height H. By controlling the solidification rate gradient and temperature field distribution of the ingot through zoned cooling, the degree of shrinkage cavities, porosity, and segregation inside the ingot is effectively reduced, the overall cooling rate of the ingot is accelerated, and the compositional segregation is reduced.

[0017] Secondly, embodiments of the present invention provide a large-size copper-nickel alloy ingot, which is produced using the production process described in the first aspect.

[0018] The beneficial effects of the technical solution provided by the embodiments of the present invention are as follows: This invention improves the solubility of metals and reduces metal burn-off while meeting composition requirements through a reasonable furnace charge ratio; it improves the compositional uniformity and microstructure density of ingots through a stepped heating melting strategy; and it significantly reduces the gas content and inclusion level in the melt through a multi-stage composite refining system, argon bottom purging protection, and optimized casting process. The combined effects of these operations can meet the production requirements of large-size, high-quality copper-nickel alloy ingots. Detailed Implementation

[0019] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0020] Example 1 A short-process production technology for large-size copper-nickel alloy ingots includes the following steps: (1) Batching and drying: Batching is carried out in accordance with GB / T 5231 standard according to the chemical composition of BFe10-1-1 copper-nickel alloy. After the batching is completed, the raw materials are placed in a drying oven and dried at 180°C for 2 hours to remove the moisture adsorbed on the surface of the raw materials. (2) Loading and preheating: The dried raw materials are loaded into the medium frequency induction melting furnace in the order of "refractory metals first, low melting point metals last". The process is as follows: cathode copper + electrolytic nickel smelting → charcoal covering → adding Fe and Mn for melting → uniform stirring → adding copper-magnesium alloy for stirring. The furnace charge is preheated at 450°C for 1.5 hours. (3) Step-by-step heating smelting: (3.1) First heating stage: The furnace temperature is raised to 1250℃ at a heating rate of 8℃ / min to fully melt the main furnace charge (nickel, copper and iron), and held at this temperature for 25 minutes; (3.2) Second heating stage: Continue to raise the furnace temperature to 1300℃ to fully melt and homogenize the alloy liquid, and hold at this temperature for 300 minutes; (3.3) Third heating stage: The furnace temperature is raised to 1370℃ for high-temperature refining and degassing, and held at this temperature for 7 minutes.

[0021] (4) Protective gas bottom purging protection Throughout the melting process in step (3), argon gas with a purity of ≥99.99% is continuously blown into the melt through five evenly distributed permeable bricks with a diameter of 0.5-2.0 mm set at the bottom of the medium-frequency induction melting furnace. The argon gas flow rate is controlled at 13 L / min and the argon gas pressure is controlled at 0.15 MPa. (5) Compound refining (5.1) Multiple slag removal: Remove the slag floating on the liquid surface, let it stand for 15 minutes, and then perform the slag removal operation again after the new slag floats to the surface. Repeat the slag removal operation 4 times until the liquid surface is clean and there is no obvious slag. (5.2) Final deoxidation refining: 15 minutes before casting, a final deoxidizer is added to the melt for final deoxidation treatment. The final deoxidizer is selected from a copper-magnesium alloy with a magnesium mass percentage of 10%, and the amount added is 0.05% of the total melt volume; (6) Pre-furnace testing and composition adjustment After the final deoxidation and refining is completed, a sample is taken from the melt using a sampling spoon, and the composition is analyzed on a spectrometer. When the test results deviate from the target composition, the corresponding intermediate alloy is added to adjust the composition until it is qualified. (7) Casting The copper-nickel alloy melt that has passed the composition test is introduced into a crystallizer that has been preheated to 250°C through a flow channel. The crystallizer is made of pure copper and has a 3mm thick graphite coating on its surface. The casting is carried out using a vertical semi-continuous casting method, and the casting temperature is controlled at 1430°C. (8) Ingot cooling and post-treatment During the casting process, a zoned cooling control measure is adopted for the ingot: the upper part of the ingot is insulated to slow down the cooling rate, while the lower part is cooled by forced water cooling to accelerate the cooling. The dividing point between the upper insulation and the lower cooling is at 1 / 2 of the ingot height. By controlling the solidification rate gradient and temperature field distribution of the ingot through zoned cooling, the degree of shrinkage cavities, porosity, and segregation inside the ingot is effectively reduced, the overall cooling rate of the ingot is accelerated, and the compositional segregation is reduced. The finished product undergoes surface cleaning and defect inspection to obtain a large-size copper-nickel alloy ingot with a diameter D of 400 mm and a height H of 3000 mm.

[0022] The chemical composition of the copper-nickel alloy ingot prepared in Example 1 was tested, and the results are shown in Table 1.

[0023] Table 1 Comparison of measured and standard values ​​of elemental content in copper-aluminum alloy ingots in Example 1 Cu margin 88 88 Ni+Co 9.0-11.0 10.01 10.02 Fe 1.0-1.5 1.23 1.25 Mn 0.5-1.0 0.698 0.692 Pb ≤0.02 0.0050 0.0048 P ≤0.006 0.0033 0.0035 S ≤0.01 0.0050 0.0050 C ≤0.05 0.0023 0.0021 Si ≤0.15 0.0010 0.0010 Zn ≤0.3 0.0082 0.0072 Sn ≤0.03 0.0018 0.0017 As can be seen from Table 1 above, the BFe10-1-1 copper-nickel alloy ingot prepared in Example 1 has a uniform chemical composition, which meets the requirements of GB / T 5231 for the chemical composition of grade BFe10-1-1.

[0024] Example 2 A short-process production technology for large-size copper-nickel alloy ingots includes the following steps: (1) Batching and drying: Batching is carried out according to the chemical composition of BFe30-1-1 copper-nickel alloy in accordance with GB / T 5231 standard. After the batching is completed, the raw materials are placed in a drying oven and dried at 250℃ for 4 hours to remove the moisture adsorbed on the surface of the raw materials. (2) Loading and preheating: The dried raw materials are loaded into the medium frequency induction melting furnace in the order of "refractory metals first, low melting point metals last". The process is as follows: cathode copper + electrolytic nickel smelting → charcoal covering → adding Fe and Mn for melting → uniform stirring → adding copper-magnesium alloy for stirring. The furnace charge is preheated at 600℃ for 2 hours. (3) Step-by-step heating smelting: (3.1) First heating stage: The furnace temperature is raised to 1280℃ at a heating rate of 13℃ / min to fully melt the main furnace charge (nickel, copper and iron), and held at this temperature for 40 minutes; (3.2) Second heating stage: Continue to raise the furnace temperature to 1350℃ to fully melt and homogenize the alloy liquid, and hold at this temperature for 60 minutes; (3.3) Third heating stage: The furnace temperature is raised to 1450℃ for high-temperature refining and degassing, and held at this temperature for 15 minutes.

[0025] (4) Protective gas bottom purging protection Throughout the melting process in step (3), argon gas with a purity of ≥99.99% is continuously blown into the melt through five evenly distributed permeable bricks with a diameter of 0.5-2.0 mm set at the bottom of the medium-frequency induction melting furnace. The argon gas flow rate is controlled at 13 L / min and the argon gas pressure is controlled at 0.15 MPa. (5) Compound refining (5.1) Repeated slag removal: Remove the slag floating on the liquid surface, let it stand for 15 minutes, and then perform the slag removal operation again after the new slag floats to the surface. Repeat the slag removal operation 4 times until the liquid surface is clean and there is no obvious slag.

[0026] (5.2) Final deoxidation refining: 15 minutes before casting, a final deoxidizer is added to the melt for final deoxidation treatment. The final deoxidizer is selected from a copper-magnesium alloy with a magnesium mass percentage of 10%, and the amount added is 0.05% of the total melt volume; (6) Pre-furnace testing and composition adjustment After the final deoxidation and refining is completed, a sample is taken from the melt using a sampling spoon, and the composition is analyzed on a spectrometer. When the test results deviate from the target composition, the corresponding intermediate alloy is added to adjust the composition until it is qualified. (7) Casting The copper-nickel alloy melt that has passed the composition test is introduced into a crystallizer that has been preheated to 300°C. The interior is pure copper and the surface is coated with a 3mm graphite layer. The casting is carried out using a vertical semi-continuous casting method, and the casting temperature is controlled at 1470°C. (8) Ingot cooling and post-treatment During the casting process, a zoned cooling control measure is adopted for the ingot: the upper part of the ingot is insulated to slow down the cooling rate, while the lower part is cooled by forced water cooling to accelerate the cooling. The dividing point between the upper insulation and the lower cooling is at 1 / 2 of the ingot height. By controlling the solidification rate gradient and temperature field distribution of the ingot through zoned cooling, the degree of shrinkage cavities, porosity, and segregation inside the ingot is effectively reduced, the overall cooling rate of the ingot is accelerated, and the compositional segregation is reduced. The finished product undergoes surface cleaning and defect inspection to obtain a large-size copper-nickel alloy ingot with a diameter D of 360 mm and a height H of 2500 mm.

[0027] Table 2 Comparison of measured and standard values ​​of elemental content in copper-aluminum alloy ingots in Example 2 Cu margin 69.1 69.1 Ni+Co 29.0-32.0 29.44 29.58 Fe 0.5-1.0 0.723 0.709 Mn 0.5-1.2 0.696 0.648 Pb ≤0.02 0.00421 0.00348 P ≤0.006 0.00554 0.00573 S ≤0.01 0.00529 0.00529 C ≤0.05 0.01 0.006 Si ≤0.15 0.00102 0.00147 Zn ≤0.3 0.0108 0.0193 Sn ≤0.03 0.00378 0.00448 As can be seen from Table 2 above, the BFe30-1-1 copper-nickel alloy ingot prepared in Example 2 has a uniform chemical composition, which meets the requirements of GB / T 5231 for the chemical composition of grade BFe30-1-1.

[0028] Finally, it should be noted that the above specific embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to examples, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A short-process production technology for large-size copper-nickel alloy ingots, characterized in that, Includes the following steps: (1) Batching and drying: Batching is carried out in accordance with GB / T 5231 standard according to the chemical composition of the target grade copper-nickel alloy. After the batching is completed, the raw materials are placed in a drying oven and dried at 150-250℃ for 2-4 hours. (2) Loading and preheating: The dried raw materials are loaded into the induction melting furnace in the order of "refractory metals first, low melting point metals last" and the raw materials are preheated at a temperature of 400-600℃ for 1-2 hours. (3) Melting: The preheated raw materials are melted by step heating. During the melting process, high-purity argon is continuously blown into the melt through the permeable bricks set at the bottom of the induction melting furnace. The argon flow rate is controlled at 10-30 L / min and the argon pressure is controlled at 0.1-0.3 MPa. (4) Multi-stage compound refining: After the melt temperature in step (3) reaches the refining temperature range, multi-stage compound refining is carried out. (5) Pre-furnace testing and composition adjustment: After the final deoxidation and refining is completed, samples are taken and the composition is analyzed on a spectrometer. When the test results deviate from the target composition, the corresponding intermediate alloy is added to adjust the composition until it is qualified. (6) Casting: The copper-nickel alloy melt that has passed the composition test is introduced into the crystallizer that has been preheated to 150-300℃ through the trough and cast using the vertical semi-continuous casting method. The casting temperature is controlled at 1430-1470℃. (7) Ingot cooling and post-treatment: During the casting process, the ingot is cooled in a zoned manner. After cooling, the surface is cleaned and defects are inspected to obtain large-size copper-nickel alloy ingots.

2. The short-process production technology for large-size copper-nickel alloy ingots according to claim 1, characterized in that, In step (3), the stepped heating smelting includes the following steps: (3.1) First heating stage: The furnace temperature is raised to 1250-1280℃ at a heating rate of 5-15℃ / min and held for 20-40min; (3.2) Second heating stage: Continue to raise the furnace temperature to 1300-1350℃ and hold for 30-60 min; (3.3) Third heating stage: Raise the furnace temperature to 1370-1450℃ and keep it warm for 5-15 minutes.

3. The short-process production technology for large-size copper-nickel alloy ingots according to claim 1, characterized in that, In step (3), the purity of the argon gas is ≥99.99%, the pore size of the permeable brick is 0.5-2.0 mm, and the number of permeable bricks is uniformly set to 2-8 according to the furnace bottom area.

4. The short-process production process for large-size copper-nickel alloy ingots according to claim 1, characterized in that, In step (4), the multi-stage compound refining includes the following steps: (4.1) Multiple slag removal: Remove the slag floating on the liquid surface, let it stand for 10-20 minutes, and then perform the slag removal operation again after new slag floats to the surface. Repeat the slag removal operation 2-4 times until the liquid surface is smooth and there is no obvious slag. (4.2) Final deoxidation refining: 10-15 minutes before casting, add a final deoxidizer to the melt for final deoxidation treatment. The amount added is 0.03%-0.08% of the total melt volume.

5. The short-process production technology for large-size copper-nickel alloy ingots according to claim 4, characterized in that, The final deoxidizer is a copper-magnesium alloy, in which the mass percentage of magnesium is 8%-15%.

6. The short-process production technology for large-size copper-nickel alloy ingots according to claim 1, characterized in that, In step (6), the crystallizer is made of pure copper and has a graphite coating with a thickness of 2-3 mm on its surface.

7. The short-process production technology for large-size copper-nickel alloy ingots according to claim 1, characterized in that, In step (7), the diameter D of the finished copper-nickel alloy ingot is ≥360 mm and the height H is ≥2000 mm.

8. The short-process production process for large-size copper-nickel alloy ingots according to claim 1, characterized in that, In step (7), the upper part of the ingot is insulated to slow down the cooling rate, and the lower part of the ingot is cooled by forced water cooling. The dividing point between the upper insulation and the lower cooling is 1 / 3 to 1 / 2 of the height H of the ingot.

9. A large-size copper-nickel alloy ingot, characterized in that, It is produced using the production process described in any one of claims 1-8.