Smelting process method for refining rare earth tellurium copper alloy ingot crystal grains and uniform structure

Abstract

The invention provides a smelting process method for refining rare earth tellurium copper alloy cast ingot grains and homogenizing tissues, and belongs to the technical field of smelting processing of copper alloys. According to the smelting process method, through the synergistic scheme that the high-purity graphite crystallizer and the ultrasonic device are adopted for vibrating the copper liquid in the semi-continuous casting stage, and the 500W type high-purity graphite powder is adopted for covering, rare earth tellurium copper alloy ingot grains can be efficiently refined, meanwhile, the ingot structure uniformity is guaranteed, inclusions are reduced, and the casting quality is improved. And a key support is provided for subsequent improvement of the processing performance and the finished product quality of the rare earth tellurium-copper alloy product. The obtained finished product is outstanding in refining and homogenizing effect, low in impurity content, high in adaptability, capable of being finely adjusted according to requirements of different production lines such as mass production, high-end production and small-scale production, simple and convenient to operate, low in equipment maintenance cost and free of extra complex investment, the oxygen content is controlled within 10 ppm, and the sum of other impurity elements is smaller than 0.0020%. The method can be widely applied to industrial production of rare earth tellurium copper alloy ingots.

Description

Technical Field

[0001] This invention belongs to the field of copper alloy smelting and processing technology, specifically relating to a smelting process method for refining the grain size and uniform structure of rare earth tellurium copper alloy ingots, which can achieve grain refinement and uniform structure of ingots, and can be adapted to the needs of industrial scale-up production. Background Technology

[0002] Copper alloys, as highly conductive copper alloy materials, contain tellurium as a second phase (Cu₂Te) distributed between or within the grains. This tellurium cannot dissolve in the copper alloy matrix, and because the second phase is relatively soft, it offers little resistance to dislocation movement, resulting in less than optimal mechanical properties for tellurium copper alloys. Rare earth tellurium copper alloys, due to the addition of rare earth elements, retain the excellent conductivity and wear resistance of tellurium copper alloys while further enhancing their corrosion resistance. Therefore, they are widely used in high-end electronic contacts, conductive components for rail transportation, and other fields. The ingot, as the base material for subsequent processing, directly determines the performance stability and processing yield of the finished product based on its grain size and microstructure uniformity.

[0003] The existing smelting process for rare earth tellurium copper alloys suffers from three major problems: First, it often uses ordinary copper crystallizers, which result in uneven heat conduction and large temperature gradients during solidification, easily leading to coarse grains. Second, it lacks effective melt disturbance methods, causing uneven distribution of trace elements such as rare earths and tellurium in the melt, resulting in ingot segregation. Third, the melt surface often lacks a dedicated covering material, making it susceptible to contact with air and the formation of oxide inclusions, further compromising the uniformity of the microstructure. These problems lead to cracking and deformation defects in rare earth tellurium copper alloy ingots produced by traditional processes during subsequent processing, making it difficult to meet the quality requirements of high-end applications.

[0004] Therefore, how to provide a smelting process for rare earth tellurium copper alloys in order to solve the problems of coarse grains, uneven structure, and many oxide inclusions caused by poor crystallization conditions, insufficient melt disturbance, and lack of surface protection in the existing rare earth tellurium copper alloy ingot smelting process has become an urgent technical problem to be solved. Summary of the Invention

[0005] This invention aims to solve the aforementioned technical problems by providing a smelting process for refining the grain size and achieving a uniform microstructure in rare earth tellurium copper alloy ingots. The technical objective of this invention is to provide a smelting process for rare earth tellurium copper alloys that addresses the problems of coarse grains, uneven microstructure, and numerous oxide inclusions caused by unfavorable crystallization conditions, insufficient melt disturbance, and lack of surface protection in existing rare earth tellurium copper alloy ingot smelting processes. This invention provides a method to overcome the shortcomings of existing processes while also ensuring good industrial adaptability.

[0006] To achieve the above-mentioned technical objectives, the technical solution adopted by the present invention is as follows: A smelting process for refining the grain size and homogeneity of rare earth tellurium copper alloy ingots includes the following steps: (1) According to the preset composition ratio of rare earth tellurium copper alloy, copper raw materials, rare earth additives and tellurium additives are put into the melting furnace for melting. Under the protection of inert gas, the alloy is heated until it is completely melted. The mixture is kept warm and stirred for 15-40 minutes to obtain a rare earth tellurium copper alloy melt (i.e. copper liquid) with uniform composition. (2) The rare earth tellurium copper alloy melt obtained in step (1) is allowed to stand at 1080-1160℃ for 10-30 min to degas. After standing, the rare earth tellurium copper alloy melt is introduced into the water-cooled assembly of the high-purity graphite crystallizer of the semi-continuous casting equipment. The inclination angle of the flow channel is controlled at 15-25° during the introduction. (3) In the high-purity graphite crystallizer of step (2), a layer of 500W high-purity graphite powder is evenly spread on the surface of rare earth tellurium copper alloy melt, with a thickness of 6-14 mm, to ensure complete coverage of the melt surface without any exposed areas. (4) Install an ultrasonic device on the outside of the high-purity graphite crystallizer to vibrate the rare earth tellurium copper alloy melt in the crystallizer. Set the ultrasonic frequency to 22-38kHz and the power to 600-1400W. The vibration continues until the traction ends. (5) Control the traction speed of the semi-continuous casting equipment to 60-140 mm / min and the cooling water volume to 900-1400 L / h to complete the continuous casting of rare earth tellurium copper alloy ingots. After the ingots are cooled to room temperature, semi-finished rare earth tellurium copper alloy ingots with fine grains and uniform structure are obtained.

[0007] The above-mentioned smelting process provided by the present invention, through the use of a high-purity graphite crystallizer and an ultrasonic device to vibrate the copper liquid in the semi-continuous casting stage, combined with a synergistic scheme of covering with 500W high-purity graphite powder, can efficiently refine the grains of rare earth tellurium copper alloy ingots, while ensuring the uniformity of ingot structure and reducing inclusions, providing key support for improving the processing performance and finished product quality of subsequent rare earth tellurium copper alloy products.

[0008] The advantages of the technical solution adopted in this invention are as follows: (1) High-purity graphite crystallizer: Compared with ordinary copper crystallizer, high-purity graphite has uniform thermal conductivity, which can significantly reduce the temperature gradient during the solidification of rare earth tellurium copper alloy melt and avoid excessive local grain growth; and its chemical stability is extremely strong, and it will not react with rare earth and tellurium elements in the melt, reducing the formation of inclusions from the source and laying the foundation for grain refinement. (2) Vibration of ultrasonic device: When ultrasonic waves act on the molten liquid, they can generate high-frequency micro-vibrations. On the one hand, they break up the coarse crystal nuclei formed in the early stage in the molten liquid, increase the number of effective crystal nuclei, and achieve grain refinement. On the other hand, they promote the diffusion of trace elements such as rare earth and tellurium in the molten liquid, avoid composition segregation, and further improve the uniformity of the ingot structure. (3) 500W high-purity graphite powder covering: 500W high-purity graphite powder has high purity and suitable particle size. When laid on the surface of the melt, it can form a dense protective layer, completely isolating the air from contact with the melt and preventing oxidation. At the same time, the graphite powder can slowly absorb heat, adjust the solidification speed of the melt surface, and work synergistically with the uniform heat conduction of the crystallizer and the melt disturbance of the ultrasonic waves to ensure that the overall solidification rhythm of the melt is consistent and to ensure that the ingot structure is uniform and defect-free.

[0009] Furthermore, in step (1), the inert gas is high-purity dehydrated argon, and the argon flow rate is 1.2-2.8 L / min.

[0010] Furthermore, the melting temperature in step (1) is 1110-1210℃.

[0011] Furthermore, the stirring speed during the heat preservation process in step (1) is 35-55 r / min.

[0012] Furthermore, the rare earth additive in step (1) is one or a mixture of lanthanum, cerium, and yttrium.

[0013] Furthermore, in step (2), high-purity dehydration argon gas is continuously introduced to assist in degassing during the static degassing process, with an argon gas flow rate of 0.6-1.8 L / min.

[0014] Furthermore, in step (3), the fixed carbon content of the 500W type high-purity graphite powder is ≥99.95%, and the particle size is 20-30μm.

[0015] Furthermore, in step (3), when applying 500W high-purity graphite powder, a uniform scraper is used to avoid graphite powder accumulation or mixing into the rare earth tellurium copper alloy melt.

[0016] Furthermore, in step (4), the vibration probe of the ultrasonic device is fixed to the outer wall of the water-cooled assembly, and the probe is cooled by circulating water during the vibration process to ensure that the probe temperature is ≤145℃.

[0017] Furthermore, in step (5), the cooling water is circulating deionized water, and the cooling water temperature is controlled at 20-30℃.

[0018] The beneficial effects of this invention are as follows: This invention's process, tailored to the material properties of rare-earth tellurium copper alloys, achieves the following three key advantages through the synergy of three core technologies: (1) Outstanding refinement and uniformity: The combination of ultrasonic waves and high-purity graphite crystallizer reduces the grain size of the ingot by more than 59% and improves the uniformity of the structure by more than 54%, completely solving the problems of coarse grains and segregation in traditional processes.

[0019] (2) Low impurity content: The covering effect of 500W high-purity graphite powder can control the oxygen content to within 10ppm and the total of other impurity elements <0.0020%, ensuring the purity of the ingot and improving the subsequent processing performance.

[0020] (3) Strong adaptability: Each process parameter can be finely adjusted according to the needs of different production lines such as mass production, high-end, and small batch. It is easy to operate, has low equipment maintenance costs, and does not require additional complex investment. It can be widely used in the industrial production of rare earth tellurium copper alloy ingots. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of this invention clearer, the invention is described in detail below with reference to embodiments. It should be noted that the following embodiments are for explanation and illustration only and are not intended to limit the invention. Non-essential improvements and adjustments made by those skilled in the art based on the above description are still within the scope of protection of this invention.

[0022] Example 1

[0023] A smelting process for refining the grain size and homogeneity of rare earth tellurium copper alloy ingots includes the following steps: (1) According to the mass production composition of rare earth tellurium copper alloy (copper 99.392%, lanthanum 0.008%, tellurium 0.60%), 500 kg of electrolytic copper, 0.04 kg of lanthanum ingots and 3 kg of tellurium blocks were put into a 500 kg medium frequency melting furnace, argon gas (flow rate 1.8 L / min) was introduced for protection, heated to 1180℃, and held and stirred for 28 min (speed 45 r / min) to obtain a rare earth tellurium copper alloy melt with uniform composition; (2) The above melt was allowed to stand at 1150℃ for 22 min to degas (argon flow rate 1.2 L / min assisted degassing), and then smoothly introduced into a high-purity graphite crystallizer with an inner diameter of 120 mm through a flow channel with an inclination angle of 20°. (3) Use a scraper to uniformly apply 500W type high-purity graphite powder (purity 99.95%, particle size 25μm) along the surface of the melt, with a thickness of 10mm, to ensure that no melt is exposed; (4) Start the ultrasonic device (external type, easy to maintain) installed on the outer wall of the crystallizer, set the frequency to 32kHz and the power to 1100W, and attach the vibration probe to the outer wall of the water-cooled crystallizer sleeve. During the vibration process, the probe is cooled by circulating water. (5) Set the semi-continuous casting speed to 110 mm / min (the casting speed adapted to the conventional mass production line), introduce circulating deionized cooling water (water temperature 26℃, the conventional outlet water temperature of the workshop), flow rate 1200 L / h, and carry out continuous casting to obtain Φ120 mm rare earth tellurium copper alloy ingot with a weight of 500 kg.

[0024] After testing the grain size, composition and oxygen content of the samples obtained by the above method, it was found that the grain size of the ingot was reduced by 62% compared with the traditional process, the uniformity of the structure was improved by 57%, the oxygen content was 6ppm, the total of other impurity elements was <0.0020%, the single furnace production cycle was 2.4h, the production cost per ton was reduced by 7.5%, and the scrap rate of subsequent processing was reduced from 6% of the traditional process to below 2%.

[0025] Example 2

[0026] A smelting process for refining the grain size and homogeneity of rare earth tellurium copper alloy ingots includes the following steps: (1) According to the composition of high-end rare earth tellurium copper alloy (copper 99.34%, cerium 0.005%, yttrium 0.005%, tellurium 0.65%), 500kg of electrolytic copper, 0.025kg of cerium ingot, 0.025kg of yttrium ingot and 3.25kg of tellurium block are put into a 500kg medium frequency melting furnace, argon gas is introduced (flow rate 2.5L / min, to enhance anti-oxidation), heated to 1190℃, and kept warm and stirred for 24min (rotation speed 50r / min, to accelerate the diffusion of trace elements) to obtain alloy melt.

[0027] (2) The melt was allowed to stand at 1160℃ for 26 minutes to remove gas (argon flow rate 1.6L / min), and then introduced into a φ120mm high-purity graphite crystallizer through a 20° inclined channel.

[0028] (3) Lay 500W type high-purity graphite powder (purity 99.95%, particle size 25μm, finer particle size to form a dense protective layer), 8mm thick, and lightly press the surface after laying to eliminate voids.

[0029] (4) Start the ultrasonic device on the outer wall of the water-cooled crystallizer, set the frequency to 36kHz and the power to 1300W (to improve the crystal nucleus crushing efficiency), and attach the vibration probe to the outer wall of the water-cooled crystallizer. During the vibration process, the probe is cooled by circulating water.

[0030] (5) Set the semi-continuous casting speed to 120 mm / min, the cooling water temperature to 28℃ and the flow rate to 1350 L / h (match the casting speed to improve the cooling intensity), and carry out continuous casting to obtain a Φ120 mm rare earth tellurium copper alloy ingot with a weight of 500 kg.

[0031] After testing the samples obtained by the above method, the grain size of the ingot was reduced by 67% compared with the traditional process, the uniformity of the structure was improved by 61%, the conductivity reached 90.5% IACS, and the wear resistance was improved by 15% compared with the traditional ingot. It fully meets the performance requirements of high-end electronic contacts, and the production efficiency is improved by 18% compared with Example 1.

[0032] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A smelting process for refining the grain size and uniform microstructure of rare earth tellurium copper alloy ingots, characterized in that... Includes the following steps: (1) According to the preset composition ratio of rare earth tellurium copper alloy, copper raw materials, rare earth additives and tellurium additives are put into the melting furnace for melting. Under the protection of inert gas, the alloy is heated until it is completely melted. The mixture is kept warm and stirred for 15-40 minutes to obtain a rare earth tellurium copper alloy melt (i.e. copper liquid) with uniform composition. (2) The rare earth tellurium copper alloy melt obtained in step (1) is allowed to stand at 1080-1160℃ for 10-30 min to degas. After standing, the rare earth tellurium copper alloy melt is introduced into the water-cooled assembly of the high-purity graphite crystallizer of the semi-continuous casting equipment. The inclination angle of the flow channel is controlled at 15-25° during the introduction. (3) In the high-purity graphite crystallizer of step (2), a layer of 500W high-purity graphite powder is evenly spread on the surface of rare earth tellurium copper alloy melt, with a thickness of 6-14 mm, to ensure complete coverage of the melt surface without any exposed areas. (4) Install an ultrasonic device on the outside of the high-purity graphite crystallizer to vibrate the rare earth tellurium copper alloy melt in the crystallizer. Set the ultrasonic frequency to 22-38kHz and the power to 600-1400W. The vibration continues until the traction ends. (5) Control the traction speed of the semi-continuous casting equipment to 60-140 mm / min and the cooling water volume to 900-1400 L / h to complete the continuous casting of rare earth tellurium copper alloy ingots. After the ingots are cooled to room temperature, semi-finished rare earth tellurium copper alloy ingots with fine grains and uniform structure are obtained.

2. The method according to claim 1, characterized in that, In step (1), the inert gas is high-purity dehydrated argon, and the argon flow rate is 1.2-2.8 L / min.

3. The method according to claim 1, characterized in that, The melting temperature in step (1) is 1110-1210℃.

4. The method according to claim 1, characterized in that, In step (1), the stirring speed during heat preservation is 35-55 r / min.

5. The method according to claim 1, characterized in that, In step (1), the rare earth additive is one or more of lanthanum, cerium, and yttrium.

6. The method according to claim 1, characterized in that, In step (2), high-purity dehydration argon is continuously introduced to assist in degassing during the static degassing process, with an argon flow rate of 0.6-1.8 L / min.

7. The method according to claim 1, characterized in that, In step (3), the fixed carbon content of the 500W type high-purity graphite powder is ≥99.95%, and the particle size is 20-30 μm.

8. The method according to claim 1, characterized in that, In step (3), when applying 500W high-purity graphite powder, a uniform scraper is used to avoid graphite powder accumulation or mixing into the rare earth tellurium copper alloy melt.

9. The method according to claim 1, characterized in that, In step (4), the vibration probe of the ultrasonic device is fixed to the outer wall of the water-cooled assembly. During the vibration process, the probe is cooled by circulating water to ensure that the probe temperature is ≤145℃.

10. The method according to claim 1, characterized in that, In step (5), the cooling water is circulating deionized water, and the cooling water temperature is controlled at 20-30℃.