A process for semi-continuous casting of copper-magnesium alloys

Abstract

The application provides a process for semi-continuous casting of copper-magnesium alloy, which is smelted by argon protection and combined with multi-element synergistic alloying, and metal elements and intermediate alloy are added in stages to improve the uniformity of composition. A vertical pulse magnetic field is introduced to cooperate with the directional solidification technology, combined with a double-layer protection of composite covering agent and boron nitride, which significantly reduces the impurity content and refines the grain structure. The multi-directional rolling process cooperates with the cyclic heat treatment method to effectively eliminate residual stress and promote the uniform distribution of precipitated phase. Through the staged aging stabilization treatment, the morphology of the precipitated phase is adjusted to realize the synergistic improvement of strength and corrosion resistance. Compared with the traditional process, the alloy obtained by the process has the advantages of dense solidification structure, excellent comprehensive performance, high yield, etc., and has important application value in the fields of aerospace and rail transportation.

Description

Technical Field

[0001] This invention belongs to the field of copper alloy technology, specifically relating to a semi-continuous casting process for copper-magnesium alloys. Background Technology

[0002] Horizontal continuous casting offers advantages such as short processes, low manufacturing costs, and high production efficiency, making it an essential production method for some alloys with poor hot-working properties. Although continuous casting can theoretically produce infinitely long thick copper plates, the 20-30 cm thick slabs it produces are often limited in application due to internal quality issues, such as insufficient plasticity, which cannot meet the cold-working deformation requirements of subsequent high-end products. Furthermore, horizontal continuous casting is suitable for a relatively limited range of alloys, consumes a large amount of crystallizer lining, and is difficult to control the uniformity of the crystal structure across the ingot cross-section. Therefore, a semi-continuous casting process for copper alloys is adopted. This process can not only produce thicker copper ingots but also add alloying elements such as magnesium during the casting process to optimize performance. It can also directly combine hot rolling or stretching processes after solidification for preliminary shaping. Moreover, semi-continuous casting features simple equipment and flexible production, making it suitable for casting various round and flat ingots of copper and copper alloys.

[0003] However, the semi-continuous casting process, especially when casting copper alloys containing elements such as magnesium, has drawbacks: an abnormal segregation layer or oxide inclusion layer rich in low-melting-point or refractory components forms on the ingot surface, which cannot fuse well with the matrix. This harmful surface alloy layer severely impairs subsequent processing performance and the quality of the final product. It must be thoroughly removed manually or mechanically as a critical pretreatment step before the ingot enters the walking beam furnace for homogenization and hot rolling. Therefore, controlling the stable fusion performance of the alloy and removing impurities are crucial aspects of the semi-continuous casting process for high-performance copper materials such as copper-magnesium alloys.

[0004] Semi-continuous casting of copper alloys is not only a core technology for upgrading the traditional copper processing industry, but also a complete technology system that can be built through cross-scale microstructure control, multi-physics field coupling, and intelligent process innovation, encompassing "high-purity melt - fine-grained homogeneous billet - high-performance products." This system provides key material support for strategic emerging industries such as new energy vehicles and next-generation communication equipment. Its technological breakthroughs have significant economic benefits and national security implications.

[0005] However, stress cracking can also occur in the semi-continuous casting process of copper alloys, mainly because heat treatment stress or processing stress is not completely eliminated, leading to structural cracks during mold failure. Therefore, in the semi-continuous casting process, the uniformity of the microstructure and impurity control directly affect the ingot quality. Furthermore, the synergistic effects of the alloying element addition sequence, the effectiveness of the covering agent, and external field auxiliary methods in existing technologies have not been fully optimized, limiting the various properties and industrial applications of high-performance copper alloys.

[0006] In existing processes, the alloy purity is easily reduced during the smelting stage due to oxidation inclusions and residual gases. Conventional covering agents, such as single salts, are insufficient to effectively prevent melt oxidation and adsorb fine inclusions. Furthermore, the lack of dynamic external field intervention during casting results in limited grain refinement, easily leading to columnar crystal formation and reduced alloy toughness. Subsequent rolling processes often employ unidirectional deformation, which may also induce anisotropy, while heat treatment regimes are insufficient for controlling precipitates, making it difficult to balance alloy strength and stability. Therefore, how to solve these problems and optimize the process of semi-continuous casting of copper alloys is the focus of this invention. Summary of the Invention

[0007] This invention discloses a semi-continuous casting process for copper-magnesium alloys to solve any of the aforementioned or potential problems in the prior art. To address the above-mentioned technical problems, this invention provides a process:

[0008] 200-220 parts of high-purity copper ingots are melted at 1150-1180℃ under argon protection. After complete melting, the mixture is held at this temperature for 30 minutes. Then, 0.8-1.2 parts of high-purity zinc ingots are added. When the temperature drops to 950℃, 2.0-2.5 parts of high-purity magnesium ingots are added. Finally, the temperature is raised to 1020-1080℃ and intermediate alloy powder is added in three batches at 5-minute intervals. After holding the mixture at this temperature for 10 minutes, a composite covering agent is spread on the alloy solution to remove slag. The mixture is then allowed to stand at 900℃ for 10 minutes before being degassed with hexachloroethane. The slag is then removed to obtain a high-purity alloy solution.

[0009] The high-purity alloy solution was semi-continuously cast at a controlled temperature of 980-1020℃, while a 50Hz, 12kA vertical pulsed magnetic field was applied simultaneously. The magnetic field direction was perpendicular to the solidification direction, with a duty cycle of 1:3. The casting speed was 3-5mm / s, and the cooling water intensity was 0.0008-0.0012m. 3 The rolling mill operates at a speed of 1000°C / min to obtain alloy ingots with a diameter of 20mm and a length of 3000-6000mm. These ingots are then subjected to heat treatment and multi-directional rolling. Preheating is performed at 500°C, with the roll axis at a 45° angle to the original rolling direction of the material. The rolling reduction is controlled at 2-6%. Annealing is then carried out at 350°C for 1 hour. Afterward, the roll axis is adjusted to 0° to the original rolling direction of the material, and the rolling reduction is controlled at 2-10%.

[0010] Aging treatment: The rolled alloy was held at 120℃ for 18 hours, heated to 165℃ at a rate of 5-10℃ / min and held for 6 hours, and then cooled to 130℃ at a rate of 3-5℃ / min and held for 12 hours for stabilization treatment.

[0011] The intermediate alloy powder includes a gas atomization process: 1.8-2.5 parts of Cu-50Al intermediate alloy, 0.12-0.16 parts of Cu-10Zr intermediate alloy, 0.15-0.25 parts of Cu-5Cr intermediate alloy and 0.5-1.2 parts of Cu-10Ce intermediate alloy are pre-melted at 1300-1500℃, and then the liquid intermediate alloy is impacted with argon gas at 3-4MPa and 2-5Mach to obtain spherical intermediate alloy powder with a particle size of 15-150μm.

[0012] The composite covering agent is made by mixing 50-60 parts spinel, 15-20 parts CaF2, 5-8 parts B2O3, 3-5 parts graphite powder, and 2-3 parts nano Al2O3, pre-melting them at 1350℃ to form a uniform glassy state, then crushing them into 0.5-2mm particles, and adding 0.1% polyethylene glycol solution to the mixed particles to obtain the composite covering agent.

[0013] The composite covering agent is evenly spread on the alloy solution with a thickness of 8-12mm.

[0014] The composite covering agent is also covered with a 3mm layer of boron nitride powder.

[0015] The heat treatment involved cooling to 430℃ and holding for 16 hours for homogenization, followed by heating to 500℃ at a rate of 5-10℃ / min and holding for 6 hours, then cooling to 480℃ at a rate of 3-5℃ / min and holding for 6 hours. This process was repeated three times, with the temperature fluctuating between 500℃ and 480℃, each time for 6 hours. Finally, the temperature was stabilized by holding at 465℃ for 10 hours.

[0016] The advantages and beneficial effects of this invention are as follows:

[0017] 1. This process refines grains through pulsed magnetic fields, improves melt cleanliness through composite covering agents, and combines multi-directional rolling with cyclic heat treatment to ultimately obtain a high-performance copper alloy with high strength, high elasticity, excellent friction resistance, stress relaxation resistance, and corrosion resistance, making it suitable for high-end fields such as aerospace.

[0018] 2. This alloy formulation achieves performance optimization through the synergistic combination of multiple metals and rare metals. The copper matrix ensures the material's basic corrosion resistance and formability; zinc and magnesium significantly enhance strength through solid solution strengthening and aging precipitation; the introduction of the master alloy enhances high-temperature stability; trace amounts of Zr and Cr refine grains and inhibit recrystallization by forming nanoparticles; rare earth Ce purifies the melt and improves heat resistance, while Ag and Yb further enhance fatigue and creep resistance by inhibiting vacancy migration and optimizing precipitate distribution. This multi-component alloy achieves a comprehensive balance between high strength and toughness.

[0019] 3. Applying a vertical pulsed magnetic field can significantly improve the solidification structure, induce micro-region flow of the melt, break the solute-rich layer at the dendrite growth front, and suppress macro-segregation. The magnetic field direction being perpendicular to the solidification direction maximizes the electromagnetic stirring effect, promotes equiaxed crystal formation, enhances grain refinement, and improves ingot homogeneity. Furthermore, the intermittent action mode with a pulse duty cycle of 1:3 avoids excessive melt turbulence that introduces oxide inclusions, while periodic perturbation strengthens solute diffusion, ultimately resulting in ingots with low porosity and high density, laying a solid foundation for subsequent processing.

[0020] 4. The spherical powder prepared by the gas atomization process has a uniform surface curvature and reduced surface roughness. When in contact with the melt, it can reduce the solid-liquid interface energy and significantly improve the diffusion coefficient of highly active elements such as Zr and Cr in the copper matrix. Secondly, the ultra-high-speed solidification induced by argon gas impact induces lattice distortion, which, combined with dislocation rearrangement, improves the fracture toughness of the alloy.

[0021] 5. Compared to single covering agents, this composite covering agent forms a high-melting-point glassy protective layer through the synergistic effect of spinel and CaF2, effectively isolating oxygen and adsorbing inclusions. The acidic properties of B2O3 neutralize alkaline oxides on the melt surface, graphite powder provides a reducing atmosphere, and nano-Al2O3 enhances the structural stability of the covering agent. After the pre-melted glassy state is broken, it is impregnated with polyethylene glycol solution, forming an organic film on the particle surface to prevent moisture absorption and improve spreading uniformity. The bilayer structure of the lower composite covering agent and the upper boron nitride powder further optimizes the heat preservation and oxygen barrier efficiency, reducing melt oxidation loss.

[0022] 6. The spinel-CaF2 system exhibits excellent chemical inertness to melts containing active elements such as Zr, Cr, and Ce, preventing contamination from reactions between the covering agent and alloying elements. B2O3 provides improved oxidation inhibition efficiency for high-zinc melts compared to traditional covering agents. Simultaneously, the low thermal conductivity of the pre-melted glassy state of the covering agent is well-suited to the rapid solidification requirements of pulsed magnetic field casting, maintaining the thermal stability of the molten pool without excessively hindering heat dissipation. The boron nitride top layer powder further reduces interfacial reactions between the melt and the covering agent, ensuring precise retention of trace additives such as high-purity Ag and Yb, thereby improving hardness.

[0023] 7. Multi-stage heat treatment promotes the dissolution and recrystallization of the second phase into nanoscale particles through three thermal shocks, eliminating residual stress; multi-directional rolling and gradient reduction induce the activation of dislocation multi-slip systems, significantly improving the isotropy of the alloy. Aging treatment, through low-temperature pre-precipitation and high-temperature coarsening control, forms a high-density region and a composite strengthening structure, thereby improving tensile strength and elongation. Detailed Implementation

[0024] The present invention will be further described in detail below with reference to the embodiments. The high-purity copper ingots used below have a purity of ≥99.95%, zinc ingots ≥99.95%, magnesium ingots ≥99.5%, and Yb and Ag metal foils have a purity of >99.9%.

[0025] Example 1

[0026] The intermediate alloy powder includes a gas atomization process: 2.2 parts of Cu-50Al intermediate alloy, 0.14 parts of Cu-10Zr intermediate alloy, 0.20 parts of Cu-5Cr intermediate alloy and 0.8 parts of Cu-10Ce intermediate alloy are pre-melted at 1400℃, and then the liquid intermediate alloy is impacted with argon gas at 3.5MPa and Mach 3.5 to obtain spherical intermediate alloy powder with a particle size of 80μm.

[0027] Composite covering agent: Mix 55 parts spinel, 18 parts CaF2, 6 parts B2O3, 4 parts graphite powder, and 2.5 parts nano Al2O3, pre-melt at 1350℃ to form a uniform glassy state, then crush to 1.2mm particles, and add 0.1% polyethylene glycol solution to the mixed particles to obtain the composite covering agent.

[0028] 210 parts of high-purity copper ingots were melted at 1165℃ under argon protection. After complete melting, the mixture was held at this temperature for 30 minutes. Then, 1.0 part of high-purity zinc ingots was added. When the temperature was lowered to 950℃, 2.2 parts of high-purity magnesium ingots were added. Finally, the temperature was raised to 1050℃ and intermediate alloy powder was added in three batches at 5-minute intervals. After holding the mixture at this temperature for 10 minutes, a 10mm composite covering agent was laid on the alloy solution, followed by a second 3mm layer of boron nitride powder for sedimentation. The mixture was then allowed to stand at 900℃ for 10 minutes and degassed with hexachloroethane. The slag was then removed to obtain a high-purity alloy solution.

[0029] The high-purity alloy solution was semi-continuously cast at a controlled temperature of 1000℃, while a 50Hz, 12kA vertical pulsed magnetic field was simultaneously applied. The magnetic field direction was perpendicular to the solidification direction, with a duty cycle of 1:3. The casting speed was 4mm / s, and the cooling water intensity was 0.001m. 3 The process involves heating the material at a rate of 8℃ / min to obtain an alloy ingot with a diameter of 20mm and a length of 4500mm. The ingot is then cooled to 430℃ and held for 16 hours for homogenization. It is then heated to 500℃ at a rate of 8℃ / min and held for 6 hours, followed by cooling to 480℃ at a rate of 4℃ / min and holding for 6 hours. This process is repeated three times, alternating between 500℃ and 480℃ for 6 hours each time, and finally stabilizing at 465℃ for 10 hours. Multi-directional rolling is then performed, with preheating at 500℃, controlling the roll axis to be 45° to the original rolling direction of the material, and controlling the rolling reduction to 4%. Annealing is then carried out at 350℃ for 1 hour. Finally, the roll axis is adjusted to be 0° to the original rolling direction of the material, and the rolling reduction is controlled to 6%.

[0030] Aging treatment: The rolled alloy was held at 120℃ for 18h, heated to 165℃ at a rate of 8℃ / min and held for 6h, and cooled to 130℃ at a rate of 4℃ / min and held for 12h for stabilization treatment.

[0031] Example 2

[0032] The intermediate alloy powder includes a gas atomization process: 1.8 parts of Cu-50Al intermediate alloy, 0.16 parts of Cu-10Zr intermediate alloy, 0.15 parts of Cu-5Cr intermediate alloy and 1.2 parts of Cu-10Ce intermediate alloy are pre-melted at 1300℃, and then the liquid intermediate alloy is impacted with argon gas at 4MPa and Mach 2 to obtain spherical intermediate alloy powder with a particle size of 150μm.

[0033] Composite covering agent: Mix 50 parts spinel, 20 parts CaF2, 5 parts B2O3, 5 parts graphite powder, and 2 parts nano Al2O3, pre-melt them at 1350℃ to form a uniform glassy state, then crush them into 2mm particles, and add 0.1% polyethylene glycol solution to the mixed particles to obtain the composite covering agent.

[0034] 220 parts of high-purity copper ingots were melted at 1180℃ under argon protection. After complete melting, the mixture was held at the temperature for 30 minutes. Then, 0.8 parts of high-purity zinc ingots were added. When the temperature was lowered to 950℃, 2.5 parts of high-purity magnesium ingots were added. Finally, the temperature was raised to 1020℃ and intermediate alloy powder was added in three batches at 5-minute intervals. After holding the temperature for 10 minutes, an 8mm composite covering agent was laid on the alloy solution, followed by a second 3mm layer of boron nitride powder for sedimentation. The mixture was then allowed to stand at 900℃ for 10 minutes and degassed with hexachloroethane. The slag was removed to obtain a high-purity alloy solution.

[0035] The high-purity alloy solution was semi-continuously cast at a controlled temperature of 980℃, while a 50Hz, 12kA vertical pulsed magnetic field was applied simultaneously. The magnetic field direction was perpendicular to the solidification direction, with a duty cycle of 1:3. The casting speed was 3mm / s, and the cooling water intensity was 0.0012m. 3 The process involves heating the material at a rate of 10℃ / min to obtain an alloy ingot with a diameter of 20mm and a length of 3000mm. The ingot is then cooled to 430℃ and held for 16 hours for homogenization. It is then heated to 500℃ at a rate of 10℃ / min and held for 6 hours, followed by cooling to 480℃ at a rate of 3℃ / min and holding for 6 hours. This process is repeated three times, alternating between 500℃ and 480℃ for 6 hours each time, and finally stabilizing at 465℃ for 10 hours. Multi-directional rolling is then performed, with preheating at 500℃, controlling the roll axis to be 45° to the original rolling direction of the material, and controlling the rolling reduction at 6%. Annealing is then carried out at 350℃ for 1 hour. Finally, the roll axis is adjusted to be 0° to the original rolling direction of the material, and the rolling reduction is controlled at 2%.

[0036] Aging treatment: The rolled alloy was held at 120℃ for 18h, heated to 165℃ at a rate of 10℃ / min and held for 6h, and cooled to 130℃ at a rate of 3℃ / min and held for 12h for stabilization treatment.

[0037] Example 3

[0038] The intermediate alloy powder includes a gas atomization process: 2.5 parts of Cu-50Al intermediate alloy, 0.12 parts of Cu-10Zr intermediate alloy, 0.25 parts of Cu-5Cr intermediate alloy and 0.5 parts of Cu-10Ce intermediate alloy are pre-melted at 1500℃, and then the liquid intermediate alloy is impacted with argon gas at 3MPa and Mach 5 to obtain spherical intermediate alloy powder with a particle size of 15μm.

[0039] Composite covering agent: Mix 60 parts spinel, 15 parts CaF2, 8 parts B2O3, 3 parts graphite powder, and 3 parts nano Al2O3, pre-melt them at 1350℃ to form a uniform glassy state, then crush them into 0.5mm particles, and add 0.1% polyethylene glycol solution to the mixed particles to obtain the composite covering agent.

[0040] 200 parts of high-purity copper ingots were melted at 1150℃ under argon protection. After complete melting, the mixture was held at this temperature for 30 minutes. Then, 1.2 parts of high-purity zinc ingots were added. When the temperature was lowered to 950℃, 2.0 parts of high-purity magnesium ingots were added. Finally, the temperature was raised to 1080℃ and intermediate alloy powder was added in three batches at 5-minute intervals. After holding the mixture at this temperature for 12 minutes, a 10mm composite covering agent was laid on the alloy solution, followed by a second 3mm layer of boron nitride powder for sedimentation. The mixture was then allowed to stand at 900℃ for 10 minutes and degassed with hexachloroethane. The slag was then removed to obtain a high-purity alloy solution.

[0041] The high-purity alloy solution was semi-continuously cast at a controlled temperature of 1020℃, while a 50Hz, 12kA vertical pulsed magnetic field was applied simultaneously. The magnetic field direction was perpendicular to the solidification direction, with a duty cycle of 1:3. The casting speed was 5mm / s, and the cooling water intensity was 0.0008m. 3 The process involves heating the material at a rate of 5℃ / min to obtain an alloy ingot with a diameter of 20mm and a length of 6000mm. The ingot is then cooled to 430℃ and held for 16 hours for homogenization. It is then heated to 500℃ at a rate of 5℃ / min and held for 6 hours, followed by cooling to 480℃ at a rate of 5℃ / min and holding for 6 hours. This process is repeated three times, alternating between 500℃ and 480℃ for 6 hours each time, and finally stabilizing at 465℃ for 10 hours. Multi-directional rolling is then performed, with preheating at 500℃, controlling the roll axis to be 45° to the original rolling direction of the material, and controlling the rolling reduction at 2%. Annealing is then carried out at 350℃ for 1 hour. Finally, the roll axis is adjusted to be 0° to the original rolling direction of the material, and the rolling reduction is controlled at 10%.

[0042] Aging treatment: The rolled alloy was held at 120℃ for 18h, heated to 165℃ at a rate of 5℃ / min and held for 6h, and then cooled to 130℃ at a rate of 5℃ / min and held for 12h for stabilization treatment.

[0043] Comparative Example 1

[0044] The difference between this comparative example and Example 1 is that the covering agent used in this comparative example is spinel. Specifically, 210 parts of high-purity copper ingots were melted at 1165°C under argon protection. After complete melting, the mixture was kept at this temperature for 30 minutes. Then, 1.0 part of high-purity zinc ingots was added. When the temperature was lowered to 950°C, 2.2 parts of high-purity magnesium ingots were added. Finally, the temperature was raised to 1050°C and intermediate alloy powder was added in three batches at 5-minute intervals. The mixture was then kept at this temperature for 10 minutes. The spinel covering agent was evenly spread on the surface of the alloy solution, with a thickness of 10 mm. A 3 mm layer of boron nitride powder was then spread on top. After slag was settled, the mixture was allowed to stand at 680°C for 10 minutes and then degassed with hexachloroethane. The slag was removed to obtain a high-purity alloy solution. The rest of the process was the same as in Example 1.

[0045] Comparative Example 2

[0046] The difference between this comparative example and Example 1 is that the covering agent in this comparative example is a single layer, specifically:

[0047] Composite covering agent: Mix 55 parts spinel, 18 parts CaF2, 6 parts B2O3, 4 parts graphite powder, and 2.5 parts nano Al2O3, pre-melt at 1350℃ to form a uniform glassy state, then crush to 1.2mm particles, and add 0.1% polyethylene glycol solution to the mixed particles to obtain the composite covering agent.

[0048] 210 parts of high-purity copper ingots were melted at 1165℃ under argon protection. After complete melting, the mixture was held at this temperature for 30 minutes. Then, 1.0 part of high-purity zinc ingots was added. When the temperature was lowered to 950℃, 2.2 parts of high-purity magnesium ingots were added. Finally, the temperature was raised to 1050℃ and intermediate alloy powder was added in three batches, with a 5-minute interval between each batch. The mixture was then held at this temperature for 10 minutes. The composite covering agent was then evenly spread on the alloy solution to a thickness of 13 mm. After slag was settled, the mixture was allowed to stand at 680℃ for 10 minutes and then degassed with hexachloroethane. The slag was then removed to obtain a high-purity alloy solution. The rest of the process was the same as in Example 1.

[0049] Comparative Example 3

[0050] The difference between this comparative example and Example 1 is that the alloy solution in this comparative example is as follows: 210 parts of high-purity copper ingots are melted at 1165°C under argon protection. After complete melting, the solution is held at this temperature for 30 minutes, then 1.0 part of high-purity zinc ingot is added. When the temperature is lowered to 950°C, 2.2 parts of high-purity magnesium ingot are added. Finally, the temperature is raised to 1050°C, and 2.2 parts of Cu-50Al master alloy, 0.14 parts of Cu-10Zr master alloy, 0.20 parts of Cu-5Cr master alloy, and 0.8 parts of Cu-10Ce master alloy are added. After holding at this temperature for 10 minutes, a 10mm composite covering agent is laid on the alloy solution, followed by a second 3mm layer of boron nitride powder for sedimentation. The solution is then allowed to stand at 900°C for 10 minutes, and then degassed with hexachloroethane. The slag is removed to obtain a high-purity alloy solution. The rest is the same as in Example 1.

[0051] Comparative Example 4

[0052] The difference between this comparative example and Example 1 is that no auxiliary magnetic field is added during the semi-continuous casting process in this comparative example. Specifically, the high-purity alloy solution is semi-continuously cast, the temperature is controlled at 1000℃, the casting speed is 4mm / s, and the cooling water intensity is 0.001m. 3 / min, to obtain an alloy ingot with a diameter of 20mm and a length of 4500mm; the rest is the same as in Example 1.

[0053] Comparative Example 5

[0054] The difference between this comparative example and Example 1 is that in this comparative example, the high-purity alloy solution is semi-continuously cast, the temperature is controlled at 1000℃, and a low-frequency alternating magnetic field with a frequency of 50Hz and a current intensity of 400A is applied simultaneously. The casting speed is 4mm / s, and the cooling water intensity is 0.001m. 3 / min, to obtain an alloy ingot with a diameter of 20mm and a length of 4500mm; the rest is the same as in Example 1.

[0055] Comparative Example 6

[0056] The difference between this comparative example and Example 1 is that no heat treatment is performed in this comparative example. Specifically, the high-purity alloy solution is semi-continuously cast, the temperature is controlled at 1000℃, and a 50Hz, 12kA vertical pulsed magnetic field is applied simultaneously. The magnetic field direction is perpendicular to the solidification direction, the duty cycle is 1:3, the casting speed is 4mm / s, and the cooling water intensity is 0.001m. 3 The rolling speed is increased to obtain an alloy ingot with a diameter of 20 mm and a length of 4500 mm. Then, multi-directional rolling is performed. The ingot is preheated at 500°C, and the roll axis is controlled at 45° to the original rolling direction of the material. The rolling reduction is controlled at 4%. The ingot is then annealed at 350°C for 1 hour. After that, the roll axis is adjusted to 0° to the original rolling direction of the material, and the rolling reduction is controlled at 6%. The rest is the same as in Example 1.

[0057] Comparative Example 7

[0058] The difference between this comparative example and Example 1 is that this comparative example uses a semi-continuous casting process for the high-purity alloy solution, controlling the temperature at 1000℃, and simultaneously applying a 50Hz, 12kA vertical pulsed magnetic field. The magnetic field direction is perpendicular to the solidification direction, with a duty cycle of 1:3, a casting speed of 4mm / s, and a cooling water intensity of 0.001m. 3 The process involves heating the material at a rate of 8°C / min to obtain an alloy ingot with a diameter of 20mm and a length of 4500mm. The ingot is then cooled to 430°C and held for 16 hours for homogenization. It is then heated to 500°C at a rate of 8°C / min and held for 18 hours. Finally, it is stabilized at 465°C for 10 hours. Multi-directional rolling is then performed, with preheating at 500°C. The roll axis is controlled at a 45° angle to the original rolling direction of the material, and the rolling reduction is controlled at 4%. Annealing is then carried out at 350°C for 1 hour. The roll axis is then adjusted to a 0° angle to the original rolling direction of the material, and the rolling reduction is controlled at 6%. The rest of the process is the same as in Example 1.

[0059] Comparative Example 8

[0060] The difference between this comparative example and Example 1 is that this comparative example does not undergo aging treatment; otherwise, it is the same as Example 1.

[0061] Comparative Example 9

[0062] The difference between this comparative example and Example 1 is that this comparative example uses a horizontal continuous casting process: First, high-purity copper ingots are put into a smelting furnace for melting. After melting, 1% Mg, 0.2% Sn, Ni, 0.5% Zn, 0.5% Al, 0.006% Zr, 0.006% Cr, and 0.025% Ce are added. Calcined charcoal is used as a covering agent to cover the liquid surface. After standing for 10 minutes, slag is removed, and then refining is continued at a temperature of 1100℃. The mixture is stirred evenly for 10 minutes, and samples are taken for chemical composition analysis to see if it meets the proportion of the ingredients. Then, horizontal continuous casting is carried out. The crystallizer is a water-cooled crystallizer lined with a high-purity graphite sleeve. The casting temperature is 1000℃, the casting speed is 15 meters per hour, the casting speed is pulled down for 2 seconds and stopped for 2 seconds, and the cooling water pressure is 0.03 MPa, resulting in an alloy ingot with a φ20mm diameter and a length of 4500mm.

[0063] Experiment 1: Performance Testing

[0064] Take copper alloy samples from Examples 1-3 and Comparative Examples 1-7 above, and test their Vickers hardness values ​​according to GB / T 4340.1-2009 "Metallic Materials - Vickers Hardness Test - Part 1: Test Method".

[0065] A microcomputer-controlled electronic universal testing machine, model DW-200E, was used. The tensile speed was 2 mm / min. Tensile strength and elongation after fracture were tested. Three specimens were tested in each group, and the average value of the results was used.

[0066] The elastic modulus of metallic materials shall be tested in accordance with GB / T 22315;

[0067] In accordance with GB / T 32791-2016 "Electromagnetic (eddy current) method for testing the conductivity of copper and copper alloys", an eddy current conductivity meter was used to detect the conductivity.

[0068] The results are shown in Table 1 below:

[0069] Table 1

[0070] Group Vickers hardness / HV Tensile strength / MPa Elongation at break / % Elastic modulus / MPa Conductivity / % Example 1 198.7 568.4 16.8 155.8 84 Example 2 196.5 556.7 16.5 154.7 83 Example 3 197.9 555.2 16.7 152.2 82 Comparative Example 1 179.5 344.5 9.5 124.5 70 Comparative Example 2 183.2 388.2 11.4 129.2 75 Comparative Example 3 181.5 348.9 9.2 128.9 71 Comparative Example 4 182.6 359.6 10.8 129.6 75 Comparative Example 5 186.8 414.9 13.5 133.9 78 Comparative Example 6 185.8 355.1 11.2 132.1 76 Comparative Example 7 189.4 409.8 13.8 142.8 78 Comparative Example 8 193.6 482.6 15.2 148.6 82 Comparative Example 9 180.1 346.2 8..4 126.2 67

Claims

1. A process for semi-continuous casting of a copper-magnesium alloy, characterized in that, The process is: 200-220 parts of high-purity copper ingot is melted at 1150-1180℃, argon is blown in for protection, after complete melting, 0.8-1.2 parts of high-purity zinc ingot is added, 2.0-2.5 parts of high-purity magnesium ingot is added when the temperature is lowered to 950℃, finally, the temperature is raised to 1020-1080℃, the intermediate alloy powder is added in three times with 5min interval, the alloy solution is then laid with the composite covering agent sediment, after 10min at 900℃, the high-purity alloy solution is obtained by removing gas with hexachloroethane and slagging; The high-purity alloy solution was semi-continuously cast at a controlled temperature of 980-1020℃, while a 50Hz, 12kA vertical pulsed magnetic field was applied simultaneously. The magnetic field direction was perpendicular to the solidification direction, with a duty cycle of 1:

3. The casting speed was 3-5mm / s, and the cooling water intensity was 0.0008-0.0012m. 3 The rolling mill operates at a speed of [speed] / min to obtain alloy ingots with a diameter of 20mm and a length of 3000-6000mm. These ingots are then subjected to heat treatment and multi-directional rolling. Preheating is performed at 500℃, with the roll axis at a 45° angle to the original rolling direction of the material. The rolling reduction is controlled at 2-6%. Annealing is then carried out at 350℃ for 1 hour. Afterward, the roll axis is adjusted to 0° to the original rolling direction of the material, with the rolling reduction controlled at 2-10%. aging treatment: the above rolled alloy is aged at 120℃ for 18h, heated to 165℃ at a rate of 5-10℃ / min for 6h, cooled to 130℃ at a rate of 3-5℃ / min for 12h for stabilization treatment; The preparation of the intermediate alloy powder includes a gas atomization process: 1.8-2.5 parts of Cu-50Al intermediate alloy, 0.12-0.16 parts of Cu-10Zr intermediate alloy, 0.15-0.25 parts of Cu-5Cr intermediate alloy and 0.5-1.2 parts of Cu-10Ce intermediate alloy are pre-melted at 1300-1500℃, then the liquid intermediate alloy is impacted by argon at 3-4MPa and 2-5 Mach speed, to obtain spherical intermediate alloy powder with a particle size of 15-150μm.

2. A process for semi-continuous casting of copper-magnesium alloys as claimed in claim 1, wherein, The preparation process of the composite covering agent is: 50-60 parts of spinel, 15-20 parts of CaF2, 5-8 parts of B2O3, 3-5 parts of graphite powder, 2-3 parts of nano-Al2O3 are mixed, then pre-melted into a uniform glass state at 1350℃, broken into 0.5-2mm particles, and 0.1% polyethylene glycol solution is added to the mixed particles to obtain the composite covering agent.

3. The process for semi-continuous casting of copper-magnesium alloy according to claim 2, characterized in that: The composite covering agent is uniformly laid on top of the alloy solution with a thickness of 8-12mm.

4. The process for semi-continuous casting of copper-magnesium alloy according to claim 3, characterized in that: A layer of 3mm boron nitride powder is also laid on the composite covering agent.