Process for semi-continuous casting of copper-magnesium alloy

Abstract

According to the semi-continuous casting process for the copper-magnesium alloy, argon protection smelting is matched with multi-element synergistic alloying, and metal elements and intermediate alloy are added in a staged gradient mode to improve the component uniformity. A vertical pulsed magnetic field synergistic directional solidification technology is introduced, and double-layer protection of a composite covering agent and boron nitride is combined, so that the impurity content is remarkably reduced, and the grain structure is refined. A multi-directional rolling process is matched with a circulating heat treatment method to effectively eliminate residual stress and promote uniform distribution of precipitated phases. And through graded aging stabilization treatment, the precipitated phase form is regulated and controlled, and synergistic improvement of strength and corrosion resistance is achieved. Compared with a traditional process, the alloy obtained through the process has the advantages of being compact in solidification structure, excellent in comprehensive performance, high in yield and the like, and has important application value in the fields of aerospace and rail transit.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of copper alloy, and particularly relates to a process for semi-continuous casting of copper-magnesium alloy. BACKGROUND

[0002] Horizontal continuous casting has the advantages of short process, low manufacturing cost and high production efficiency, and is a necessary production mode for some alloy materials with poor hot workability. Although continuous casting can theoretically produce infinitely long rough copper plates, the 20-30 cm thick slabs produced by continuous casting are often limited in application due to internal quality problems such as insufficient plasticity, which cannot meet the cold working deformation required by subsequent high-end products. In addition, the alloy variety applicable to horizontal continuous casting is relatively single, the consumption of the inner sleeve of the crystallizer is large, and the uniformity of the crystallization structure of the cross section of the ingot is not easy to control. Therefore, the semi-continuous casting process for copper alloy can not only produce thicker copper ingots, but also can add alloying elements such as magnesium during casting to optimize the performance, and can directly combine with hot rolling or stretching and other hot deformation processes for preliminary forming after solidification. In addition, semi-continuous casting has the characteristics of simple equipment and flexible production, and is suitable for casting round and flat ingots of various copper and copper alloys.

[0003] However, the semi-continuous casting process has defects, especially when casting copper alloys containing magnesium and other elements. A layer of abnormal segregation layer or oxidation inclusion layer rich in low-melting-point or refractory components, which cannot be well fused with the matrix, is formed on the surface of the cast ingot. This harmful surface alloy seriously damages the subsequent processing performance and the quality of the final product, and must be completely removed by manual or mechanical polishing as a key pretreatment step before the cast ingot enters the step-by-step heating furnace for homogenization and hot rolling. Therefore, controlling the performance of stable fusion of the alloy and removing impurities is a crucial link in the production process of semi-continuous casting of high-performance copper materials such as copper-magnesium alloy.

[0004] Semi-continuous casting of copper alloy is not only the core technology of the traditional copper processing industry. Through cross-scale organization regulation and control, multi-physical field coupling and intelligent process innovation, a full-chain technology system of "high-purity melt-fine-grain homogeneous cast slab-high-performance product" can be constructed to provide key material support for strategic emerging industries such as new energy vehicles and new generation communication equipment. Its technological breakthrough has significant economic benefits and national security significance.

[0005] However, stress cracks may occur during the process of semi-continuous casting of copper alloy, mainly due to the fact that the heat treatment stress or processing stress is not completely eliminated, and the microstructure cracks are generated in the process of mold failure. Therefore, the uniformity of the microstructure and the control of impurities directly affect the quality of the cast ingot during the semi-continuous casting process. However, the synergistic effect of the addition sequence of alloying elements, the efficiency of covering agent and the external field auxiliary means has not been fully optimized in the prior art, which limits the performance of high-performance copper alloy and its industrial application.

[0006] In the existing process, the purity of the alloy is easily reduced due to oxidation inclusions and gas residues during the smelting stage. Conventional covering agents, such as single salts, are difficult to effectively isolate the melt from oxidation and adsorb fine slag inclusions. In addition, the casting process lacks dynamic external field intervention, the grain refinement effect is limited, and columnar crystals are easily formed, which reduces the toughness of the alloy material. The subsequent rolling process mostly uses unidirectional deformation, which may also cause anisotropy, and the heat treatment system is insufficient to control the precipitated phase, making it difficult to balance the strength and stability of the alloy. Therefore, how to solve the above problems and optimize the process of semi-continuous casting of copper alloys is the research focus of the present invention. Summary of the Invention

[0007] The present invention discloses a process for semi-continuous casting of copper-magnesium alloy to solve the above-mentioned and potential problems in the prior art. In order to solve the above-mentioned technical problems, the present invention provides a process:

[0008] 200-220 parts of high-purity copper ingots are melted at 1150-1180°C, and argon gas is introduced for protection. After being completely melted, the mixture is kept warm for 30 minutes, and then 0.8-1.2 parts of high-purity zinc ingots are added. When the temperature drops to 950°C, 2.0-2.5 parts of high-purity magnesium ingots are added. Finally, the temperature is raised to 1020-1080°C, and the master alloy powder is added in three batches, each with an interval of 5 minutes. The mixture is kept warm for 10 minutes, and composite covering agent sediment is laid on the alloy solution. The mixture is then allowed to stand at 900°C for 10 minutes, and then degassed with hexachloroethane. The slag is skimmed to obtain a high-purity alloy solution.

[0009] The high-purity alloy solution was semi-continuously cast at a controlled temperature of 980-1020°C, and a 50Hz, 12kA vertical pulse magnetic field was applied simultaneously. The magnetic field direction was perpendicular to the solidification direction, the duty cycle was 1:3, the casting speed was 3-5mm / s, and the cooling water intensity was 0.0008-0.0012m 3 / min, to obtain an alloy ingot with a diameter of 20mm and a length of 3000-6000mm; then heat treatment, multi-directional rolling, preheating at 500℃, controlling the axis of the roll to be 45° with the original rolling direction of the material, controlling the rolling reduction by 2-6%, and annealing at 350℃ for 1h, and then adjusting the axis of the roll to be 0° with the original rolling direction of the material, and controlling the rolling reduction by 2-10%;

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

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

[0012] The composite covering agent is prepared by mixing 50-60 parts of spinel, 15-20 parts of CaF2, 5-8 parts of B2O3, 3-5 parts of graphite powder, and 2-3 parts of nano-Al2O3, pre-melting the mixture at 1350°C into a uniform glassy state, crushing the mixture 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 8-12 mm.

[0014] A layer of 3mm boron nitride powder is also laid on the composite covering agent.

[0015] Among them, the heat treatment is to cool down to 430℃, keep it warm for 16 hours for homogenization treatment, then heat it to 500℃ at a rate of 5-10℃ / min, keep it warm for 6 hours, and then cool it to 480℃ at a rate of 3-5℃ / min, keep it warm for 6 hours. Three thermal cycle treatments of 500℃ and 480℃ are carried out, each time keeping warm for 6 hours, and stabilized at 465℃ for 10 hours.

[0016] The advantages and beneficial effects of the present invention are:

[0017] 1. This process uses a pulsed magnetic field to refine grains, a composite covering agent to improve melt cleanliness, and multi-directional rolling to perform cyclic heat treatment, ultimately producing 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 formula achieves optimized performance 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 a master alloy enhances high-temperature stability; trace amounts of Zr and Cr form nanoparticles to refine grains and inhibit recrystallization; the rare earth element Ce purifies the melt and improves heat resistance, while Ag and Yb further enhance fatigue and creep resistance by inhibiting vacancy migration and optimizing precipitation distribution. This multi-component alloy achieves a comprehensive balance of high strength and toughness.

[0019] 3. The application of vertical pulsed magnetic field can significantly improve the solidified tissue, induce melt micro-zone flow, break the solute enrichment layer of dendrite growth front, and inhibit macrosegregation. The electromagnetic stirring effect is maximized when the magnetic field direction is perpendicular to the solidification direction, which promotes equiaxed crystal formation, grain refinement, and improves the homogeneity of the ingot. In addition, the intermittent mode of pulse duty ratio 1:3 can not only avoid the introduction of oxidation inclusions caused by excessive melt turbulence, but also strengthen solute diffusion through periodic disturbance, ultimately obtaining a low porosity and high density ingot, laying a good foundation for subsequent processing.

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

[0021] 5. Compared with a single covering agent, the composite covering agent forms a high-melting-point glassy protective layer through the synergy of spinel and CaF2, effectively isolating oxygen and adsorbing inclusions. The acidic nature of B2O3 can neutralize the basic oxides on the surface of the melt, graphite powder provides a reducing atmosphere, and nano-Al2O3 enhances the structural stability of the covering agent. After the pre-melted glass state is broken and infiltrated with polyethylene glycol solution, an organic film is formed on the surface of the particles, preventing moisture absorption and improving spreading uniformity. The double-layer structure of the lower composite covering agent and the upper boron nitride powder further optimizes the heat preservation and oxygen resistance efficiency, reducing the oxidation loss of the melt.

[0022] 6. The spinel-CaF2 system has excellent chemical inertness for melts containing active elements such as Zr, Cr, and Ce, avoiding contamination of the covering agent and alloy elements. At the same time, the low thermal conductivity of the pre-melted glass state of the covering agent is compatible with the rapid solidification requirements of pulsed magnetic field casting, which can maintain the thermal stability of the melt pool without excessive hindering heat dissipation. The upper layer of boron nitride powder further reduces the interfacial reaction between the melt and the covering agent, ensuring the accurate retention rate of trace additive elements such as high-purity Ag and Yb, thereby improving the hardness.

[0023] 7. Multi-stage heat treatment promotes the dissolution and re-precipitation of the second phase into nano-sized particles through three thermal shocks, eliminating residual stress; multi-directional rolling and gradient reduction induce dislocation multi-slip systems to significantly improve the isotropy of the alloy. The aging treatment regulates the pre-precipitation at low temperature and coarsening at high temperature, forming a high-density zone and a composite strengthening structure, thereby improving the tensile strength and elongation. DETAILED DESCRIPTION

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

[0025] Example 1

[0026] The master alloy powder includes a gas atomization process: 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 pre-melted at 1400°C, and then the liquid master alloy is impacted with argon at 3.5MPa and 3.5 Mach speed to obtain spherical master alloy powder with a particle size of 80μm.

[0027] Composite covering agent: Mix 55 parts of spinel, 18 parts of CaF2, 6 parts of B2O3, 4 parts of graphite powder, and 2.5 parts of nano-Al2O3, pre-melt them at 1350℃ into a uniform glass state, then crush them into 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°C, and argon gas was introduced for protection. After being completely melted, the mixture was kept warm for 30 minutes, and then 1.0 part of high-purity zinc ingot was added. When the temperature dropped to 950°C, 2.2 parts of high-purity magnesium ingot were added. Finally, the mixture was heated to 1050°C and the master alloy powder was added in three batches, each with an interval of 5 minutes. The mixture was kept warm for 10 minutes, and a 10mm composite covering agent was laid on the alloy solution, followed by a second layer of 3mm boron nitride powder to precipitate the residue. The mixture was then allowed to stand at 900°C for 10 minutes, and then degassed with hexachloroethane. The residue was skimmed to obtain a high-purity alloy solution.

[0029] The high-purity alloy solution was semi-continuously cast at a controlled temperature of 1000°C, and a 50Hz, 12kA vertical pulse magnetic field was applied simultaneously. The magnetic field direction was perpendicular to the solidification direction, the duty cycle was 1:3, the casting speed was 4mm / s, and the cooling water intensity was 0.001m 3 / min, to obtain an alloy ingot with a diameter of 20mm and a length of 4500mm; then cool to 430℃, keep it for 16h for homogenization treatment, then heat to 500℃ at a rate of 8℃ / min, keep it for 6h, then cool to 480℃ at a rate of 4℃ / min, keep it for 6h, implement three thermal cycles of 500℃ and 480℃, keep it for 6h each time, and keep it at 465℃ for 10h for stabilization; then carry out multi-directional rolling, preheat at 500℃, control the axis of the roll to be 45° with the original rolling direction of the material, control the rolling reduction by 4%, and anneal at 350℃ for 1h, then adjust the axis of the roll to be 0° with the original rolling direction of the material, and control the rolling reduction by 6%;

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

[0031] Example 2

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

[0033] Composite covering agent: Mix 50 parts of spinel, 20 parts of CaF2, 5 parts of B2O3, 5 parts of graphite powder, and 2 parts of nano-Al2O3, pre-melt them at 1350℃ into a uniform glass 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°C, and argon gas was introduced for protection. After being completely melted, the mixture was kept warm for 30 minutes, and then 0.8 parts of high-purity zinc ingots were added. When the temperature dropped to 950°C, 2.5 parts of high-purity magnesium ingots were added. Finally, the mixture was heated to 1020°C and the master alloy powder was added in three batches, each with an interval of 5 minutes. After the mixture was kept warm for 10 minutes, an 8mm composite covering agent was laid on the alloy solution, and then a second layer of 3mm boron nitride powder was laid to precipitate the residue. The mixture was then allowed to stand at 900°C for 10 minutes, and then degassed with hexachloroethane. The residue was skimmed to obtain a high-purity alloy solution.

[0035] The high-purity alloy solution was semi-continuously cast at a controlled temperature of 980°C, and a 50Hz, 12kA vertical pulse magnetic field was applied simultaneously. The magnetic field direction was perpendicular to the solidification direction, the duty cycle was 1:3, the casting speed was 3mm / s, and the cooling water intensity was 0.0012m 3 / min, to obtain an alloy ingot with a diameter of 20mm and a length of 3000mm; then cool to 430℃, keep it for 16h for homogenization treatment, then heat to 500℃ at a rate of 10℃ / min, keep it for 6h, then cool to 480℃ at a rate of 3℃ / min, keep it for 6h, implement three thermal cycles of 500℃ and 480℃, keep it for 6h each time, and keep it at 465℃ for 10h for stabilization; then carry out multi-directional rolling, preheat at 500℃, control the axis of the roll to be 45° with the original rolling direction of the material, control the rolling reduction by 6%, and anneal at 350℃ for 1h, then adjust the axis of the roll to be 0° with the original rolling direction of the material, and control the rolling reduction by 2%;

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

[0037] Example 3

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

[0039] Composite covering agent: Mix 60 parts of spinel, 15 parts of CaF2, 8 parts of B2O3, 3 parts of graphite powder, and 3 parts of nano-Al2O3, pre-melt them at 1350℃ into a uniform glass 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°C, and argon gas was introduced for protection. After being completely melted, the mixture was kept warm for 30 minutes, and then 1.2 parts of high-purity zinc ingots were added. When the temperature dropped to 950°C, 2.0 parts of high-purity magnesium ingots were added. Finally, the temperature was raised to 1080°C, and the master alloy powder was added in three batches, with an interval of 5 minutes each time. The mixture was kept warm for 12 minutes, and a 10mm composite covering agent was laid on the alloy solution, followed by a second layer of 3mm boron nitride powder to precipitate the residue. The mixture was then allowed to stand at 900°C for 10 minutes, and then degassed with hexachloroethane. The residue was skimmed to obtain a high-purity alloy solution.

[0041] The high-purity alloy solution was semi-continuously cast at a controlled temperature of 1020°C, and a 50Hz, 12kA vertical pulse magnetic field was applied simultaneously. The magnetic field direction was perpendicular to the solidification direction, the duty cycle was 1:3, the casting speed was 5mm / s, and the cooling water intensity was 0.0008m 3 / min, to obtain an alloy ingot with a diameter of 20mm and a length of 6000mm; then cool to 430℃, keep it for 16h for homogenization treatment, then heat to 500℃ at a rate of 5℃ / min, keep it for 6h, then cool to 480℃ at a rate of 5℃ / min, keep it for 6h, implement three thermal cycles of 500℃ and 480℃, keep it for 6h each time, and keep it at 465℃ for 10h for stabilization; then carry out multi-directional rolling, preheat at 500℃, control the axis of the roll to be 45° with the original rolling direction of the material, control the rolling reduction by 2%, and anneal at 350℃ for 1h, then adjust the axis of the roll to be 0° with the original rolling direction of the material, and control the rolling reduction by 10%;

[0042] Aging treatment: The rolled alloy was kept at 120°C for 18 h, heated to 165°C at a rate of 5°C / min and kept for 6 h, and cooled to 130°C at a rate of 5°C / min and kept for 12 h 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 smelted at 1165°C, and argon gas was introduced for protection. After being completely melted, the mixture was kept warm for 30 minutes, and then 1.0 part of high-purity zinc ingot was added. When the temperature dropped to 950°C, 2.2 parts of high-purity magnesium ingots were added. Finally, the temperature was raised to 1050°C, and the master alloy powder was added in three batches, each with an interval of 5 minutes. The mixture was then kept warm for 10 minutes. The spinel covering agent was evenly laid on the lower layer of the surface contacting the alloy solution with a thickness of 10 mm, and a 3 mm thick boron nitride powder was laid on the upper layer. After the slag was precipitated, the mixture was allowed to stand at 680°C for 10 minutes, degassed with hexachloroethane, and the slag was skimmed to obtain a high-purity alloy solution. The rest 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 layer, specifically:

[0047] Composite covering agent: Mix 55 parts of spinel, 18 parts of CaF2, 6 parts of B2O3, 4 parts of graphite powder, and 2.5 parts of nano-Al2O3, pre-melt them at 1350℃ into a uniform glass state, then crush them into 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°C and protected by argon gas. After being completely melted, the mixture was kept warm for 30 minutes, and then 1.0 part of high-purity zinc ingot was added. When the temperature dropped to 950°C, 2.2 parts of high-purity magnesium ingots were added. Finally, the temperature was raised to 1050°C and the master alloy powder was added in three batches, each with an interval of 5 minutes. The mixture was then kept warm for 10 minutes, and a composite covering agent was evenly laid on the alloy solution to a thickness of 13 mm. After the slag was precipitated, the mixture was allowed to stand at 680°C for 10 minutes, degassed with hexachloroethane, and the slag was skimmed to obtain a high-purity alloy solution. The rest 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 of this comparative example is as follows: 210 parts of high-purity copper ingots are smelted at 1165° C., argon gas is introduced for protection, and after complete melting, the mixture is kept warm for 30 minutes, followed by the addition of 1.0 part of high-purity zinc ingot. When the temperature drops to 950° C., 2.2 parts of high-purity magnesium ingots are added. Finally, the temperature is raised to 1050° C., 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. The mixture is kept warm for 10 minutes, a 10 mm composite covering agent is laid on the alloy solution, and then a second layer of 3 mm boron nitride powder is laid to precipitate the residue. The mixture is then allowed to stand at 900° C. for 10 minutes, degassed with hexachloroethane, and slag is skimmed 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 in this comparative example, no auxiliary magnetic field is added during the semi-continuous casting process. Specifically, the high-purity alloy solution is semi-continuously cast with a controlled temperature of 1000°C, a casting speed of 4 mm / s, and a cooling water intensity of 0.001 m 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°C, and a low-frequency alternating magnetic field with a frequency of 50 Hz and a current intensity of 400 A is applied at the same time, the casting speed is 4 mm / s, and the cooling water intensity is 0.001 m 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°C, and a 50Hz, 12kA vertical pulse magnetic field is applied simultaneously, the magnetic field direction is perpendicular to the solidification direction, the duty ratio is 1:3, 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 20 mm and a length of 4500 mm; then multi-directional rolling was carried out, preheated at 500°C, the axis of the roll was controlled to be 45° to the original rolling direction of the material, the rolling reduction was controlled to 4%, and annealed at 350°C for 1h, and then the axis of the roll was adjusted to be 0° to the original rolling direction of the material, and the rolling reduction was controlled to 6%; the rest was the same as in Example 1.

[0057] Comparative Example 7

[0058] 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°C, and a 50Hz, 12kA vertical pulse magnetic field is applied at the same time, the magnetic field direction is perpendicular to the solidification direction, the duty ratio is 1:3, 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; then cool to 430℃, keep warm for 16h for homogenization treatment, then heat to 500℃ at a rate of 8℃ / min, keep warm for 18 hours, then cool to 480℃ at a rate of 4℃ / min, keep warm for 18 hours, and finally keep warm at 465℃ for 10h for stabilization; then carry out multi-directional rolling, preheat at 500℃, control the axis of the roll to be 45° with the original rolling direction of the material, control the rolling reduction by 4%, and anneal at 350℃ for 1h, then adjust the axis of the roll to be 0° with the original rolling direction of the material, and control the rolling reduction by 6%; the rest 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, and the rest is the same as Example 1.

[0061] Comparative Example 9

[0062] The difference between this comparative example and Example 1 is that a horizontal continuous casting process is adopted in this comparative example: a high-purity copper ingot is first put into a smelting furnace for smelting, and then 1% Mg, 0.2% Sn, Ni, 0.5% Zn, 0.5% Al, 0.006% Zr, 0.006% Cr, and 0.025% Ce are added after melting. The liquid surface is covered with calcined charcoal as a covering agent, and the mixture is allowed to stand for 10 minutes. The slag is then removed and refined at a temperature of 1100°C and stirred evenly for 10 minutes. Samples are taken for chemical composition analysis to see whether they meet the proportion of the ingredients; horizontal continuous casting is then carried out, and the crystallizer adopts a water-cooled crystallizer lined with a high-purity graphite sleeve. The casting temperature is 1000°C, and the casting speed is 15 meters per hour, with a pull-down period of 2 seconds and a stop period of 2 seconds. The cooling water pressure is 0.03 MPa to obtain an alloy ingot with a diameter of 20 mm and an ingot length of 4500 mm.

[0063] Test 1: Performance testing

[0064] The copper alloy samples of Examples 1-3 and Comparative Examples 1-7 were taken and the Vickers hardness values ​​were tested according to GB / T 4340.1-2009 “Vickers hardness test of metallic materials Part 1: Test method”.

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

[0066] Test the elastic modulus of metal materials according to GB / T 22315;

[0067] According to GB / T 32791-2016 “Electromagnetic (eddy current) method for testing the electrical conductivity of copper and copper alloys”, an eddy current conductivity meter is used to test the electrical 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 copper-magnesium alloy, characterized in that: The process is: 200-220 parts of high-purity copper ingots are melted at 1150-1180°C, and argon gas is introduced for protection. After being completely melted, the mixture is kept warm for 30 minutes, and then 0.8-1.2 parts of high-purity zinc ingots are added. When the temperature drops to 950°C, 2.0-2.5 parts of high-purity magnesium ingots are added. Finally, the temperature is raised to 1020-1080°C, and the master alloy powder is added in three batches, each with an interval of 5 minutes. The mixture is kept warm for 10 minutes, and composite covering agent sediment is laid on the alloy solution. The mixture is then allowed to stand at 900°C for 10 minutes, and then degassed with hexachloroethane. The slag is skimmed to obtain a high-purity alloy solution. The high-purity alloy solution was semi-continuously cast at a controlled temperature of 980-1020°C, and a 50Hz, 12kA vertical pulse magnetic field was applied simultaneously. The magnetic field direction was perpendicular to the solidification direction, the duty cycle was 1:3, the casting speed was 3-5mm / s, and the cooling water intensity was 0.0008-0.0012m 3 / min, to obtain an alloy ingot with a diameter of 20mm and a length of 3000-6000mm; then heat treatment, multi-directional rolling, preheating at 500℃, controlling the axis of the roll to be 45° with the original rolling direction of the material, controlling the rolling reduction by 2-6%, and annealing at 350℃ for 1h, and then adjusting the axis of the roll to be 0° with the original rolling direction of the material, and controlling the rolling reduction by 2-10%; Aging treatment: The rolled alloy was kept at 120°C for 18 hours, heated to 165°C at a rate of 5-10°C / min and kept for 6 hours, and cooled to 130°C at a rate of 3-5°C / min and kept for 12 hours for stabilization treatment.

2. A process for semi-continuous casting of copper-magnesium alloy according to claim 1, characterized in that: Master alloy powder includes gas atomization process: 1.8-2.5 parts of Cu-50Al master alloy, 0.12-0.16 parts of Cu-10Zr master alloy, 0.15-0.25 parts of Cu-5Cr master alloy and 0.5-1.2 parts of Cu-10Ce master alloy are pre-melted at 1300-1500°C, and then the liquid master alloy is impacted with argon at 3-4 MPa and 2-5 Mach speed to obtain spherical master alloy powder with a particle size of 15-150 μm.

3. The process for semi-continuous casting of copper-magnesium alloy according to claim 1, characterized in that: The composite covering agent is: Mix 50-60 parts of spinel, 15-20 parts of CaF2, 5-8 parts of B2O3, 3-5 parts of graphite powder, and 2-3 parts of nano-Al2O3, pre-melt them at 1350°C into a uniform glass state, then crush them into 0.5-2mm particles, and add 0.1% polyethylene glycol solution to the mixed particles to obtain a composite covering agent.

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

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

6. The process for semi-continuous casting of copper-magnesium alloy according to claim 1, characterized in that: The heat treatment is to cool to 430°C, keep it warm for 16 hours for homogenization, then heat it to 500°C at a rate of 5-10°C / min, keep it warm for 6 hours, then cool it to 480°C at a rate of 3-5°C / min, keep it warm for 6 hours, and implement three thermal cycle treatments at 500°C and 480°C, each keeping warm for 6 hours, and finally keep it warm at 465°C for 10 hours for stabilization.