Preparation method of nanoparticle reinforced 7000 series aluminum alloy welding wire

Abstract

The invention discloses a preparation method of a nanoparticle reinforced 7000 series aluminum alloy welding wire, belongs to the technical field of aluminum alloy processing, and particularly relates to a preparation method of a nanoparticle reinforced 7000 series aluminum alloy welding wire. The invention aims to solve the problems that a high-strength, high-modulus and low-plasticity aluminum-based composite material is difficult in cold deformation and cannot be prepared into a cold-drawn filament. The method comprises the following steps: 1, carrying out homogenizing annealing on a nano-particle reinforced 7000 series aluminum alloy cast ingot; 2, heating in a box-type furnace, and extruding in an extruding cylinder of an extruding machine; thirdly, annealing treatment is conducted, and cold drawing is conducted after annealing; and fourthly, the operation in the third step is repeated till the nano-particle reinforced 7000 series aluminum alloy welding wire with the diameter phi being 2.6 mm is prepared. The nano-particle reinforced 7000 series aluminum alloy welding wire prepared through the method can be used for multiple fields such as aerospace and has huge application potential.

Description

Technical Field

[0001] The invention belongs to the technical field of aluminum alloy processing, and in particular relates to a method for preparing a nano-particle reinforced 7000 series aluminum alloy welding wire. Background Art

[0002] In recent years, ceramic particle reinforced aluminum matrix composites have attracted extensive attention as high-performance materials with the potential for large-scale production. Nanoparticle reinforced aluminum matrix composites have better mechanical properties than traditional aluminum alloys, especially high specific strength and specific modulus, good thermal and electrical conductivity, good wear resistance, and excellent high-temperature mechanical properties. They have broad application prospects in the fields of automobiles, electronic packaging, aerospace, etc. Particle reinforced aluminum matrix composites are currently the first choice for lightweight structural materials due to their excellent comprehensive properties such as excellent casting performance, low density, high specific strength and specific modulus, good plasticity and wear resistance, and low manufacturing cost.

[0003] With the gradual use of 7000 series aluminum-based composite materials, domestic scholars have made the commonly used special aluminum alloy AA7075, which cannot be welded, weldable. The resulting products are expected to be used in fields such as automobile manufacturing, making their parts lighter and more energy-efficient while maintaining their strength. Nanoparticle-reinforced aluminum-based composite materials will gradually be put into use.

[0004] As nanoparticle-reinforced aluminum-based composite materials are about to be put into practical use, the development of welding wires that match them is particularly important. Once successfully developed, the welding performance of high-strength aluminum alloys will be greatly improved. However, due to the high strength, high modulus and low plasticity of nanoparticle-reinforced aluminum-based composite materials, the following problems will occur:

[0005] 1. High strength means that the material can withstand large stress without obvious deformation when subjected to external force. During cold deformation, such as cold drawing, when tension is applied to the material, stress distribution will occur inside the material. However, due to its high strength, even if a large external force is applied, it is not easy for the material to evenly disperse the stress through local plastic flow like low-strength materials. On the contrary, stress is easily concentrated in certain local areas of the material. Once these local stresses exceed the limit that the material can withstand, cracks will be generated, thereby hindering the continuation of cold deformation, and ultimately failing to prepare the material into cold-drawn filaments.

[0006] 2. High modulus means that the material has very little elastic deformation when subjected to external force. During the cold drawing process, the material will first undergo an elastic deformation stage, and then enter the plastic deformation stage to achieve shape changes, such as being drawn into filaments. However, since the elastic deformation range of high modulus aluminum-based composite materials is very limited, when external force is applied, the material will quickly reach the limit of elastic deformation and it is difficult to smoothly transition to the plastic deformation stage, so it is impossible to be drawn into filaments through continuous plastic deformation. Moreover, during the deformation process, the deformation coordination between different internal regions is also poor. In the cold drawing operation, the material needs to deform evenly in each part to be successfully drawn into filaments. However, the high modulus makes the material tend to deform independently according to its own stiffness characteristics when subjected to external force, and it is difficult to achieve overall coordinated deformation. This easily leads to excessive or insufficient local deformation of the material during the cold drawing process, which in turn causes damage to the material and makes it impossible to complete the cold drawing operation of preparing filaments.

[0007] 3. Low-plasticity aluminum-based composite materials themselves lack sufficient plastic deformation capacity. During the cold drawing process, they cannot change their shape through a large amount of plastic flow like high-plasticity materials. Since the preparation of cold-drawn filaments requires that the material can continuously undergo plastic deformation to gradually reduce the cross-sectional area and elongate, low-plasticity materials obviously cannot meet this requirement, and therefore are difficult to prepare into cold-drawn filaments. When subjected to external forces, brittle fracture is more likely to occur. Moreover, during the cold drawing process, even if a relatively small external force is applied, due to the insufficient plasticity of the material, the energy brought by the external force cannot be dissipated through plastic deformation. The external force energy is easy to accumulate inside the material. Once the fracture limit of the material is reached, it will cause the material to break suddenly, and the purpose of cold drawing into filaments cannot be achieved.

[0008] In summary, due to the combined influence of the above-mentioned factors, high-strength, high-modulus, and low-plasticity aluminum-based composites face many difficulties during the cold deformation process and cannot be effectively prepared into cold-drawn filaments. Summary of the invention

[0009] The present invention aims to solve the problem that high-strength, high-modulus, low-plasticity aluminum-based composite materials are difficult to cold-deform and cannot be prepared into cold-drawn filaments, and provides a method for preparing nanoparticle-reinforced 7000 series aluminum alloy welding wires.

[0010] A method for preparing a nanoparticle-reinforced 7000 series aluminum alloy welding wire is specifically carried out in the following steps:

[0011] 1. Using nanoparticles to reinforce 7000 series aluminum alloy ingots, homogenizing annealing is performed at 450-480°C for 24-48 hours, and then the nanoparticles reinforced aluminum-based composite material ingots are obtained after being processed into car skins;

[0012] 2. The obtained nanoparticle-reinforced aluminum-based composite ingot is placed in a box furnace for heating at a temperature of 400-440°C and a holding time of 1-8 hours; then the ingot is placed in an extrusion barrel of an extruder for extrusion at an extrusion speed of ≤0.1 mm / s, and the extrusion barrel is kept at a constant temperature of 400-420°C to obtain an extruded wire billet;

[0013] 3. Annealing the extruded wire billet, and then cold drawing it. During the cold drawing process, the deformation amount of a single cold drawing is controlled within 15% to 30%;

[0014] 4. Repeat the operation described in step 3 until a φ2.6 mm nanoparticle reinforced 7000 series aluminum alloy welding wire is prepared.

[0015] The beneficial effects of the present invention are:

[0016] 1. The present invention discloses a method for preparing a nano-particle reinforced 7000 series aluminum alloy welding wire. The high-strength, high-modulus, low-plasticity aluminum-based composite material does not crack or break during the cold deformation process. When the elongation is less than 7%, a cold-drawn filament with a diameter of less than 3 mm is prepared.

[0017] 2. The present invention discloses a method for preparing a nanoparticle-reinforced 7000 series aluminum alloy welding wire, which can realize the preparation of the 7000 series aluminum alloy welding wire, and at the same time make the 7000 series aluminum alloy weldable, and use the same alloy for welding to improve the welding strength. The nanoparticle-reinforced 7000 series aluminum alloy welding wire prepared by the method, after welding the nanoparticle-reinforced 7000 series aluminum alloy plate, is subjected to a solid solution treatment at 460°C to 480°C for 30 to 50 minutes, and then an aging treatment is performed at a temperature of 121°C for 18 hours to 24 hours, and the weld strength can reach more than 350MPa. The present invention is suitable for the preparation of nanoparticle-reinforced 7000 series aluminum alloy welding wire. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This is a physical picture of the nanoparticle-reinforced 7000 series aluminum alloy welding wire obtained in the example. DETAILED DESCRIPTION

[0019] Specific implementation method 1: In this implementation method, a method for preparing a nanoparticle-reinforced 7000 series aluminum alloy welding wire is specifically carried out in the following steps:

[0020] 1. Using nanoparticles to reinforce 7000 series aluminum alloy ingots, homogenizing annealing is performed at 450-480°C for 24-48 hours, and then the nanoparticles reinforced aluminum-based composite material ingots are obtained after being processed into car skins;

[0021] 2. The obtained nanoparticle-reinforced aluminum-based composite ingot is placed in a box furnace for heating at a temperature of 400-440°C and a holding time of 1-8 hours; then the ingot is placed in an extrusion barrel of an extruder for extrusion at an extrusion speed of ≤0.1 mm / s, and the extrusion barrel is kept at a constant temperature of 400-420°C to obtain an extruded wire billet;

[0022] 3. Annealing the extruded wire billet, and then cold drawing it. During the cold drawing process, the deformation amount of a single cold drawing is controlled within 15% to 30%;

[0023] 4. Repeat the operation described in step 3 until a φ2.6 mm nanoparticle reinforced 7000 series aluminum alloy welding wire is prepared.

[0024] Step 1 of this embodiment helps to eliminate the component segregation and structural inhomogeneity formed during the solidification process of the ingot. For aluminum-based composite materials with high strength, high modulus and low plasticity, the initial structural inhomogeneity may lead to large differences in local performance, and cracks or difficulty in deformation may occur due to stress concentration and other problems during cold deformation. Through homogenization annealing, the internal structure of the material is made more uniform, and the performance of each part tends to be consistent, thereby providing a relatively uniform foundation for subsequent cold deformation operations and reducing the possibility of difficulty in cold deformation caused by structural inhomogeneity.

[0025] Step 2: The extrusion process is a hot working method. At an appropriate temperature and a low extrusion speed, the material will undergo dynamic recrystallization. Dynamic recrystallization can refine the grain structure of the material and reduce the grain size. For aluminum-based composite materials that originally have low plasticity, the refined grain structure can significantly improve the plasticity of the material. Because the grain boundary area of ​​the fine grains increases during the deformation process, the grain boundaries can hinder the movement of dislocations, which alleviates the accumulation and blockage of dislocations at the grain boundaries, thereby improving the material's ability to withstand deformation, that is, the plasticity is enhanced, which lays a good plastic foundation for the subsequent cold drawing operation and reduces the difficulty of cold deformation.

[0026] In step three and step four, the extruded wire billet is first annealed before cold drawing, and the single-pass cold drawing deformation is controlled at 15%-30% during the cold drawing process. Annealing after each cold drawing can eliminate the work hardening phenomenon generated during the previous cold drawing process. The plasticity of the material is restored by annealing, and then the next cold drawing operation is performed, and the single-pass cold drawing deformation is reasonably controlled to avoid problems such as cracks or fractures in the material due to insufficient plasticity caused by excessive single deformation. At the same time, these operations are repeated until the welding wire of the required specifications is prepared. Through multiple gradual cold drawing deformations, rather than cold drawing with too large a deformation at one time, the material can gradually reach the target size while constantly adjusting the state, effectively solving the problem that high-strength, high-modulus, low-plasticity aluminum-based composite materials are difficult to directly prepare into cold-drawn filaments.

[0027] Specific embodiment 2: This embodiment is different from the specific embodiment 1 in that the preparation of the nanoparticle-reinforced 7000 series aluminum alloy ingot in step 1 is specifically carried out according to the following steps:

[0028] 1. Obtaining electrolytic aluminum liquid by electrolysis of the original aluminum block;

[0029] 2. Adding a mixed salt of K2TiF6 and KBF4 into the electrolytic aluminum water, and mechanically stirring to make the particles evenly distributed; the mass ratio of K2TiF6 to KBF4 in the mixed salt of K2TiF6 and KBF4 is 1.2:1;

[0030] 3. After converter treatment, filtration, slag refining, degassing and standing, casting is performed, and electromagnetic stirring technology is used during casting to cast a nanoparticle-reinforced 7000 series aluminum alloy ingot with a specification of φ100-140mm×600mm; the reinforcing phase in the nanoparticle-reinforced 7000 series aluminum alloy ingot is nano-TiB2 / TiC ceramic particles, and the added content is 20wt%. Others are the same as the specific implementation method one.

[0031] Specific implementation method three: This implementation method is different from specific implementation method one in that: in step one, homogenization annealing is performed at 470° C. for 24 hours. The rest is the same as specific implementation method one.

[0032] Specific embodiment 4: This embodiment differs from specific embodiment 1 in that: in step 2, the obtained nanoparticle-reinforced aluminum-based composite ingot is placed in a box furnace for heating at a temperature of 420°C and a holding time of 1 hour; then it is placed in an extrusion barrel of an extruder for extrusion at an extrusion speed of 0.06 mm / s, and the extrusion barrel is kept at a constant temperature of 400°C to obtain an extruded wire billet. The rest is the same as specific embodiment 1.

[0033] Specific embodiment 5: This embodiment differs from specific embodiment 1 in that the extrusion die used in step 2 has two symmetrical holes, the hole shape is a circle of φ10.8 mm. Others are the same as specific embodiment 1.

[0034] Specific implementation method 6: This implementation method is different from the specific implementation method 1 in that the annealing treatment in step 3 is specifically performed according to the following steps:

[0035] 1. Heat the box-type heat treatment furnace to 400-450°C, and after the furnace gas reaches the temperature, send the extruded wire billet into the furnace;

[0036] 2. Monitor the material temperature. After the extruded wire billet reaches the furnace temperature, keep it warm for 2 to 3 hours.

[0037] 3. The insulated blank is cooled to room temperature in a box-type heat treatment furnace, with a furnace cooling rate of 10-15°C / h and a cooling time of 14-18h; during the cooling process, the blank is continuously heated by the box-type heat treatment furnace to replenish the temperature. Others are the same as the first embodiment.

[0038] Specific implementation method 7: This implementation method is different from the specific implementation method 1 in that: in step 3, the deformation amount of single-pass cold drawing is controlled at 25% during the cold drawing process. The rest is the same as the specific implementation method 1.

[0039] Specific implementation example 8: This implementation example is different from specific implementation example 1 in that: in step 4, step 3 is repeated 7 to 10 times. The rest is the same as specific implementation example 1.

[0040] Specific embodiment 9: This embodiment differs from specific embodiment 1 in that: the tensile strength of the nanoparticle-reinforced 7000 series aluminum alloy welding wire in step 4 is ≥700MPa; Young's modulus is ≥80GPa. Other aspects are the same as those of specific embodiment 1.

[0041] Specific embodiment ten: This embodiment differs from specific embodiment one in that when the nanoparticle-reinforced 7000 series aluminum alloy welding wire described in step four is used to weld the nanoparticle-reinforced 7000 series aluminum alloy plate, after solid solution treatment at 460-480°C for 30-50 minutes, aging treatment is performed at 121°C for 18-24 hours, and the weld strength reaches more than 350MPa. Others are the same as specific embodiment one.

[0042] The following examples are used to verify the beneficial effects of the present invention:

[0043] A method for preparing a nanoparticle-reinforced 7000 series aluminum alloy welding wire is specifically carried out in the following steps:

[0044] 1. Obtaining electrolytic aluminum liquid by electrolysis of the original aluminum block;

[0045] 2. Adding a mixed salt of K2TiF6 and KBF4 into the electrolytic aluminum water, and mechanically stirring to make the particles evenly distributed; the mass ratio of K2TiF6 to KBF4 in the mixed salt of K2TiF6 and KBF4 is 1.2:1;

[0046] 3. After converter treatment, filtration, slag refining, degassing and standing, casting is performed, and electromagnetic stirring technology is used during casting to cast a nano-particle reinforced 7000 series aluminum alloy ingot with a specification of φ130mm×600mm; the reinforcing phase in the nano-particle reinforced 7000 series aluminum alloy ingot is nano-TiB2 / TiC ceramic particles, and the added content is 20wt%;

[0047] Fourth, using nanoparticles to reinforce 7000 series aluminum alloy ingots, homogenizing annealing at 470°C for 24 hours, and obtaining nanoparticle-reinforced aluminum-based composite ingots after car skinning;

[0048] 5. The obtained nanoparticle-reinforced aluminum-based composite ingot is placed in a box furnace for heating at a temperature of 420°C and a holding time of 1 hour; then, it is placed in an extrusion barrel of an extruder for extrusion at an extrusion speed of 0.06 mm / s, and the extrusion barrel is kept at a constant temperature of 400°C to obtain an extruded wire billet;

[0049] 6. Raise the temperature of the box-type heat treatment furnace to 410°C, and after the furnace gas reaches the temperature, send the extruded wire billet into the furnace; monitor the material temperature, and keep the extruded wire billet warm for 2 hours after it reaches the furnace temperature; cool the insulated billet to room temperature in the box-type heat treatment furnace, with a furnace cooling rate of 13°C / h and a cooling time of 16 hours; during the cooling process, the billet is continuously heated by the box-type heat treatment furnace to make up the temperature, and then cold-drawn, and the deformation amount of single-pass cold drawing is controlled at 25% during the cold-drawing process;

[0050] 7. Repeat step 3 7 to 10 times to prepare a φ2.6 mm nanoparticle reinforced 7000 series aluminum alloy welding wire.

[0051] In this embodiment, nanoparticle-reinforced 7000 series aluminum alloy welding wire is prepared. Figure 1 As shown, after heat treatment, the tensile strength is ≥700MPa; the Young's modulus is ≥80GPa.

[0052] In this embodiment, nanoparticle-reinforced 7000 series aluminum alloy welding wire is prepared. After welding the nanoparticle-reinforced 7000 series aluminum alloy plate, it is solution treated at 460°C to 480°C for 30 to 50 minutes and then aged at 121°C for 18 to 24 hours. The weld strength can reach above 350 MPa.

Claims

1. A method for preparing a nanoparticle-reinforced 7000 series aluminum alloy welding wire, characterized in that The preparation method of nanoparticle reinforced 7000 series aluminum alloy welding wire is specifically carried out in the following steps:

1. Using nanoparticles to reinforce 7000 series aluminum alloy ingots, homogenizing annealing is performed at 450-480°C for 24-48 hours, and then the nanoparticles reinforced aluminum-based composite material ingots are obtained after being processed into car skins; 2. The obtained nanoparticle-reinforced aluminum-based composite ingot is placed in a box furnace for heating at a temperature of 400-440°C and a holding time of 1-8 hours; then the ingot is placed in an extrusion barrel of an extruder for extrusion at an extrusion speed of ≤0.1 mm / s, and the extrusion barrel is kept at a constant temperature of 400-420°C to obtain an extruded wire billet; 3. Annealing the extruded wire billet, and then cold drawing it. During the cold drawing process, the deformation amount of a single cold drawing is controlled within 15% to 30%; 4. Repeat the operation described in step 3 until a φ2.6 mm nanoparticle reinforced 7000 series aluminum alloy welding wire is prepared.

2. The method for preparing a nanoparticle-reinforced 7000 series aluminum alloy welding wire according to claim 1, characterized in that The preparation of the nanoparticle-reinforced 7000 series aluminum alloy ingot in step 1 is specifically carried out according to the following steps:

1. Obtaining electrolytic aluminum liquid by electrolysis of the original aluminum block; 2. Adding a mixed salt of K2TiF6 and KBF4 into the electrolytic aluminum water, and mechanically stirring to make the particles evenly distributed; the mass ratio of K2TiF6 to KBF4 in the mixed salt of K2TiF6 and KBF4 is 1.2:1; 3. After converter treatment, filtration, slag refining, degassing and standing, casting is carried out. During casting, electromagnetic stirring technology is used to cast nanoparticle-reinforced 7000 series aluminum alloy ingots with specifications of φ100~140mm×600mm; the reinforcing phase in the nanoparticle-reinforced 7000 series aluminum alloy ingots is nano-TiB2 / TiC ceramic particles, and the added content is 20wt%.

3. The method for preparing a nanoparticle-reinforced 7000 series aluminum alloy welding wire according to claim 1, characterized in that In step 1, homogenization annealing is performed at 470° C. for 24 h.

4. The method for preparing a nanoparticle-reinforced 7000 series aluminum alloy welding wire according to claim 1, characterized in that In step 2, the obtained nanoparticle reinforced aluminum-based composite ingot is placed in a box furnace for heating at a temperature of 420°C and a holding time of 1 hour; then it is placed in an extrusion barrel of an extruder for extrusion at an extrusion speed of 0.06 mm / s, and the extrusion barrel is kept at a constant temperature of 400°C to obtain an extruded wire billet.

5. The method for preparing a nanoparticle-reinforced 7000 series aluminum alloy welding wire according to claim 1, characterized in that The extrusion die used for the extrusion in step 2 has two symmetrical holes, and the hole shape is a circle of φ10.8 mm.

6. The method for preparing a nanoparticle-reinforced 7000 series aluminum alloy welding wire according to claim 1, characterized in that The annealing treatment in step 3 is specifically carried out according to the following steps:

1. Heat the box-type heat treatment furnace to 400-450°C, and after the furnace gas reaches the temperature, send the extruded wire billet into the furnace; 2. Monitor the material temperature. After the extruded wire billet reaches the furnace temperature, keep it warm for 2 to 3 hours.

3. The insulated blank is cooled to room temperature in a box-type heat treatment furnace. The furnace cooling rate is 10-15°C / h and the cooling time is 14-18h. During the cooling process, the blank is continuously heated by the box-type heat treatment furnace to supplement the temperature.

7. The method for preparing a nanoparticle-reinforced 7000 series aluminum alloy welding wire according to claim 1, characterized in that In step 3, the deformation amount of a single cold drawing pass is controlled within 25% during the cold drawing process.

8. The method for preparing a nanoparticle-reinforced 7000 series aluminum alloy welding wire according to claim 1, characterized in that In step 4, repeat step 3 7 to 10 times.

9. The method for preparing a nanoparticle-reinforced 7000 series aluminum alloy welding wire according to claim 1, characterized in that The nanoparticle-reinforced 7000 series aluminum alloy welding wire described in step 4 has a tensile strength of ≥700MPa and a Young's modulus of ≥80GPa.

10. The method for preparing a nanoparticle-reinforced 7000 series aluminum alloy welding wire according to claim 1, characterized in that When the nanoparticle-reinforced 7000 series aluminum alloy welding wire described in step 4 is used to weld the nanoparticle-reinforced 7000 series aluminum alloy plate, after solid solution treatment at 460-480°C for 30-50 minutes, aging treatment is performed at 121°C for 18-24 hours, and the weld strength reaches above 350MPa.

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