Ultra-high-strength aluminum alloy wire for aerospace fasteners and manufacturing method thereof

Abstract

An ultra-high-strength aluminum alloy wire for aerospace fasteners and a manufacturing method thereof. The present invention relates to an ultra-high-strength aluminum alloy wire for aerospace fasteners and a manufacturing method thereof. The purpose of the present invention is to solve the problems of uneven deformation of the structure, insufficient strength, low electrical conductivity, poor plasticity and easy cracking of existing high-strength aluminum alloy wires. An ultra-high-strength aluminum alloy wire for aerospace fasteners is composed of Cu, Mg, Zn, Zr and the balance of Al. Method: 1. Weighing raw materials; 2. Casting of aluminum alloy ingots; 3. Homogenization annealing of aluminum alloy ingots; 4. Sawing and car skin; 5. Preheating of aluminum alloy ingots; 6. Preparation of wire by rolling; 7. Intermediate annealing of wires; 8. Cold drawing; 9. Annealing of finished products; 10. Heat treatment. The aluminum alloy wire of the present invention has high connection strength, good resistance to stress corrosion and anti-relaxation performance. The present invention is applied to the field of aluminum alloys.

Description

Technical Field

[0001] The invention relates to an ultra-high-strength aluminum alloy wire for aerospace fasteners and a manufacturing method thereof. Background Art

[0002] With the continuous improvement of the requirements for transportation efficiency in aerospace, higher and more urgent requirements have been put forward for fasteners in terms of light weight, high strength, high toughness, corrosion resistance, anti-loosening and repeated installation. Among them, weight reduction and efficiency improvement have gradually become a difficult problem that needs to be solved urgently. However, at present, aerospace connection fasteners are basically based on 45# steel, ML25, 1Cr18Ni9Ti and other materials. Among them, there are many low-strength steel fasteners, and their weight accounts for a large proportion of structural fasteners, which cannot meet the weight reduction needs of new models. Comparing steel and high-strength aluminum alloys of the same level of strength, it can be seen that the density of the 7XXX series of ultra-high-strength aluminum alloys that can be heat-treated and strengthened is only one-third of that of steel, and it has good toughness, strong stress corrosion resistance, and high fatigue resistance. Therefore, the use of new high-strength aluminum alloy fasteners to upgrade 600MPa-grade steel fasteners has become an important solution for rocket weight reduction. In addition, aluminum resources are abundant, alloy properties are stable, easy to process, and low in cost. New high-strength alloy fasteners are ideal materials for aerospace vehicle structures. They can replace low-strength steel used in non-main load-bearing parts of current rockets, thereby improving the connection performance of rocket structures and reducing structural weight. This is of great significance for improving the level of aerospace structural equipment. Summary of the invention

[0003] The purpose of the present invention is to solve the problems of uneven deformation, insufficient strength, low conductivity, poor plasticity and easy cracking of existing high-strength aluminum alloy wires, and to provide an ultra-high-strength aluminum alloy wire for aerospace fasteners and a manufacturing method thereof.

[0004] The invention discloses an ultra-high strength aluminum alloy wire for aerospace fasteners, which is composed of Cu: 2.0%-2.6%, Mg: 1.8%-2.3%, Zn: 7.6%-8.4%, Zr: 0.12%-0.20% and the balance Al in terms of mass percentage.

[0005] The present invention provides a method for manufacturing an ultra-high strength aluminum alloy wire for aerospace fasteners as follows:

[0006] 1. Melting of aluminum alloy ingots: weigh aluminum ingots, pure magnesium ingots, pure zinc ingots, electrolytic copper, aluminum-copper master alloy, and AlZr3 master alloy as raw materials according to the element mass percentage of Cu: 2.0% to 2.6%, Mg: 1.8% to 2.3%, Zn: 7.6% to 8.4%, Zr: 0.12% to 0.20% and the balance is Al; add the weighed raw materials into a smelting furnace, the smelting temperature is 720°C to 760°C, the smelting heating time is 2h to 6h, and then refine to obtain aluminum liquid;

[0007] 2. Casting of aluminum alloy ingots: Cast the aluminum liquid obtained in step 1 at a casting temperature of 700°C to 735°C, a casting speed of 60mm / min to 100mm / min, a casting water pressure of 0.04MPa to 0.07MPa, and a cooling water temperature of 15°C to 25°C to obtain an aluminum alloy ingot with a diameter of 170mm;

[0008] 3. Homogenizing annealing of the aluminum alloy ingot: placing the ingot obtained in step 2 into a resistance heating furnace for homogenizing annealing to obtain a homogenizing annealed ingot;

[0009] 4. Sawing and lathing: The surface oxide scale of the homogenized annealed ingot is removed by lathing to obtain an aluminum alloy ingot with a diameter of 145 mm to 162 mm, which is then cut into cast rod ingots with a length of 3000 mm to 5500 mm to obtain an aluminum alloy rolled rough ingot;

[0010] 5. Preheating of aluminum alloy ingot: Load the aluminum alloy rolled rough ingot into a pusher-type resistance heating furnace, keep it warm for 2h to 6h at a temperature of 390°C to 430°C, and obtain the preheated aluminum alloy rolled rough ingot;

[0011] 6. Preparation of wire rod by rolling: placing the preheated aluminum alloy rolled raw material ingot in a hot rolling mill for rolling to obtain hot rolled wire rod;

[0012] 7. Intermediate annealing of the wire: put the hot-rolled wire obtained in step 6 into a resistance heating furnace, keep it at a temperature of 400°C to 420°C for 2h to 3h, cool it to below 180°C to 210°C, then heat it to 220°C to 240°C and keep it at that temperature for 4h to 6h, then take it out of the furnace and air cool it to obtain an annealed aluminum alloy wire;

[0013] 8. Cold drawing: cold drawing the annealed aluminum alloy wire under the condition of deformation rate of 25% to 45%, and then repeating annealing and cold drawing to obtain the aluminum alloy wire in cold drawing state;

[0014] IX. Finished product annealing: put the cold drawn aluminum alloy wire into a resistance heating furnace, keep it at 400℃~420℃ for 2h~3h, cool it to below 180℃~210℃, then heat it to 220℃~240℃ and keep it for 4h~6h, then take it out of the furnace and air cool it to obtain aluminum alloy wire rod;

[0015] 10. The aluminum alloy wire rod is subjected to solution treatment, quenching and aging treatment in a quenching furnace to obtain ultra-high strength aluminum alloy wire for aerospace fasteners.

[0016] Beneficial effects of the present invention:

[0017] 1. The present invention adopts casting to solve the quality problem of high-alloyed aluminum alloy body. The quality of the ingot reaches the AA-level flaw detection requirement, and the production and model trial of ultra-high-strength alloy wire fastener products are realized for the first time.

[0018] 2. The present invention provides a method for preparing high-strength aluminum alloy wire for aerospace fasteners. The prepared ultra-high-strength aluminum alloy wire is produced by hot rolling + drawing, which solves the problem of ultra-high-strength aluminum alloy being produced by extrusion and drawing, resulting in serious coarse grain rings and reduced wire performance. When fastener products are processed, they must be used at reduced specifications, which increases the production cost of the fasteners and affects production automation control.

[0019] 3. The special intermediate annealing process and finished product annealing process are adopted to ensure the distribution of precipitation phase after wire annealing and the hardness of the billet, so as to achieve a more suitable cold working state, ensure the realization of the suitable cold deformation of the high-alloyed 7000 series wire, and then control the wire structure and performance. The first stage high temperature section annealing at 400℃~420℃ / 2h~3h eliminates the work hardening and the organization is restored; the cooling rate is not less than 30℃ per hour to below 180℃~210℃, and the size and distribution of the annealing cooling precipitation phase are controlled. The second stage low temperature section annealing at 220℃~240℃ / 4h~6h is conducive to the continuous precipitation and growth of the precipitation phase in the grain and the grain boundary, and the grain boundary phase is transformed from continuous to discontinuous, which can improve the corrosion performance of the wire. At the same time, the appropriate growth of the strengthening phase can effectively reduce the material strength, which is conducive to the subsequent control of the cold deformation of the wire. Otherwise, the cold deformation of the high-alloyed ultra-high strength 7000 series alloy is very difficult.

[0020] 4. Through the double-stage solution treatment of the wire, the first stage eliminates the phase of the first low melting point melting peak, and the second stage eliminates the phase of the second high melting point melting peak. The low melting point melting peak AlZnMgCu (T phase) and the high melting point melting peak Al2CuMg (S phase) are fully melted back to increase the density and volume fraction of the aging precipitation phase and enhance the strengthening effect.

[0021] 5. Double-stage aging treatment effectively regulates the size and distribution of precipitated phases, which can make the precipitated phases in the alloy crystal present the peak aging state, and the precipitated phases at the grain boundary present the over-aging state with discontinuous distribution. Two kinds of spherical and lamellar precipitates are precipitated in the alloy matrix as GP zone and η' phase with coherent and semi-coherent relationship with Al matrix. The strengthening phases of the alloy are GP zone and η' phase. The strengthening mechanism of the alloy is the joint strengthening of GP zone and η' phase. The precipitates at the alloy boundary have been completely disconnected, and a very narrow (20-30nm) grain boundary non-precipitation zone has appeared. The disconnected grain boundary precipitates are very beneficial to improving the stress corrosion resistance of the alloy. Therefore, through the double-stage aging treatment, the requirements of strengthening and corrosion resistance are taken into account, and the matching of ultra-high strength and good corrosion performance is achieved.

[0022] 6. The present invention has developed a method for preparing ultra-high-strength aluminum alloy wire, which has been used for key aerospace connectors, with high connection strength, good stress corrosion resistance and anti-relaxation performance. The tensile strength of the aluminum alloy wire for high-performance aerospace fasteners reaches 630MPa-680MPa, the specified non-proportional elongation strength reaches 590MPa-620MPa, the elongation after fracture reaches more than 10.0%, the electrical conductivity is more than 35% IACS, and the corrosion resistance is good, which can provide a new type of ultra-high-strength aluminum alloy material for ultra-high-strength fasteners in the aerospace field. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is a physical picture of the high-strength aluminum alloy wire for aerospace fasteners prepared in Example;

[0024] Figure 2 This is a physical picture of the ultra-high-strength MJ threaded bolt fastener product produced using high-strength aluminum alloy wire for aerospace fasteners;

[0025] Figure 3 The microstructure diagram of the aluminum alloy ingot obtained in step 2 of Example 1;

[0026] Figure 4 The metallographic structure of the annealed wire obtained after the finished product annealing in step nine of Example 1;

[0027] Figure 5 This is the microstructure diagram of the T76 wire obtained in step 10 of Example 1;

[0028] Figure 6 This is a transmission photograph of the T76 state wire obtained in step ten of Example 1. DETAILED DESCRIPTION

[0029] The technical solution of the present invention is not limited to the specific implementation modes listed below, but also includes any combination of the specific implementation modes.

[0030] Specific implementation method 1: In this implementation method, an ultra-high strength aluminum alloy wire for aerospace fasteners is composed of Cu: 2.0% to 2.6%, Mg: 1.8% to 2.3%, Zn: 7.6% to 8.4%, Zr: 0.12% to 0.20% and the balance Al in terms of mass percentage.

[0031] Specific implementation method 2: In this implementation method, a method for manufacturing an ultra-high strength aluminum alloy wire for aerospace fasteners is as follows:

[0032] 1. Melting of aluminum alloy ingots: weigh aluminum ingots, pure magnesium ingots, pure zinc ingots, electrolytic copper, aluminum-copper master alloy, and AlZr3 master alloy as raw materials according to the element mass percentage of Cu: 2.0% to 2.6%, Mg: 1.8% to 2.3%, Zn: 7.6% to 8.4%, Zr: 0.12% to 0.20% and the balance is Al; add the weighed raw materials into a smelting furnace, the smelting temperature is 720°C to 760°C, the smelting heating time is 2h to 6h, and then refine to obtain aluminum liquid;

[0033] 2. Casting of aluminum alloy ingots: Cast the aluminum liquid obtained in step 1 at a casting temperature of 700°C to 735°C, a casting speed of 60mm / min to 100mm / min, a casting water pressure of 0.04MPa to 0.07MPa, and a cooling water temperature of 15°C to 25°C to obtain an aluminum alloy ingot with a diameter of 170mm;

[0034] 3. Homogenizing annealing of the aluminum alloy ingot: placing the ingot obtained in step 2 into a resistance heating furnace for homogenizing annealing to obtain a homogenizing annealed ingot;

[0035] 4. Sawing and lathing: The surface oxide scale of the homogenized annealed ingot is removed by lathing to obtain an aluminum alloy ingot with a diameter of 145 mm to 162 mm, which is then cut into cast rod ingots with a length of 3000 mm to 5500 mm to obtain an aluminum alloy rolled rough ingot;

[0036] 5. Preheating of aluminum alloy ingot: Load the aluminum alloy rolled rough ingot into a pusher-type resistance heating furnace, keep it warm for 2h to 6h at a temperature of 390°C to 430°C, and obtain the preheated aluminum alloy rolled rough ingot;

[0037] 6. Preparation of wire rod by rolling: placing the preheated aluminum alloy rolled raw material ingot in a hot rolling mill for rolling to obtain hot rolled wire rod;

[0038] 7. Intermediate annealing of the wire: put the hot-rolled wire obtained in step 6 into a resistance heating furnace, keep it at a temperature of 400°C to 420°C for 2h to 3h, cool it to below 180°C to 210°C, then heat it to 220°C to 240°C and keep it at that temperature for 4h to 6h, then take it out of the furnace and air cool it to obtain an annealed aluminum alloy wire;

[0039] 8. Cold drawing: cold drawing the annealed aluminum alloy wire under the condition of deformation rate of 25% to 45%, and then repeating annealing and cold drawing to obtain the aluminum alloy wire in cold drawing state;

[0040] IX. Finished product annealing: put the cold drawn aluminum alloy wire into a resistance heating furnace, keep it at 400℃~420℃ for 2h~3h, cool it to below 180℃~210℃, then heat it to 220℃~240℃ and keep it for 4h~6h, then take it out of the furnace and air cool it to obtain aluminum alloy wire rod;

[0041] 10. The aluminum alloy wire rod is subjected to solution treatment, quenching and aging treatment in a quenching furnace to obtain ultra-high strength aluminum alloy wire for aerospace fasteners.

[0042] In order to strictly control the content of iron, silicon impurities and Na+Li+K alkali metals in this embodiment, the Fe content in the aluminum ingot is less than 0.005, the Si content is less than 0.005, and the Na+Li+K alkali metal content is less than 3ppm;

[0043] In this embodiment, aluminum titanium boron wire is dotted online during casting, and the amount of aluminum titanium boron wire added is: the amount of Ti element dotted in the raw material is 0.005wt%.

[0044] In the repeated annealing and cold stretching in step eight of this embodiment, the annealing process of step seven and the cold stretching process of step eight are adopted.

[0045] Specific embodiment 3: This embodiment differs from specific embodiment 2 in that: in step 1, argon-chlorine mixed gas is used for refining for 20 to 40 minutes, and the argon-chlorine mixed gas is a mixture of 96% argon and 4% chlorine by molar volume. The rest is the same as specific embodiment 1.

[0046] Specific embodiment 4: This embodiment is different from specific embodiment 2 or 3 in that the homogenization annealing in step 3 is first kept at 430° C. for 8 h to 12 h, and then kept at 470° C. for 48 h to 60 h. The rest is the same as specific embodiment 2 or 3.

[0047] Specific embodiment 5: This embodiment differs from specific embodiments 2 to 4 in that the cooling rate in steps 7 and 9 when cooling to below 180°C to 210°C is ≥30°C / h. Other aspects are the same as those of specific embodiments 2 to 4.

[0048] Specific embodiment 6: This embodiment is different from specific embodiments 2 to 5 in that the solid solution in step 10 is kept at 450°C for 60 to 120 minutes, and then heated to 470°C for 90 to 180 minutes. The rest is the same as specific embodiments 2 to 5.

[0049] Specific embodiment 7: This embodiment is different from specific embodiments 2 to 6 in that the quenching in step 10 is quenching in water at a temperature of 0° C. to 35° C. The rest is the same as specific embodiments 1 to 5.

[0050] Specific embodiment eight: This embodiment differs from specific embodiments two to seven in that the aging treatment in step ten is: the quenched aluminum alloy wire is kept at a temperature of 117°C to 123°C for 4h to 10h, then heated to 157°C to 163°C and kept for 4h to 10h. The rest is the same as specific embodiments two to seven.

[0051] Specific embodiment 9: This embodiment is different from specific embodiments 2 to 8 in that: step 8 is to perform cold stretching through a stretching and sizing die. The rest is the same as specific embodiments 2 to 8.

[0052] Specific embodiment 10: This embodiment is different from specific embodiments 2 to 9 in that the tensile strength of the aluminum alloy wire for high-performance aerospace fasteners reaches 630MPa to 680MPa, the non-proportional elongation strength reaches 590MPa to 620MPa, the elongation after fracture is greater than 10.0%, and the electrical conductivity is greater than 35% IACS. Other aspects are the same as specific embodiments 2 to 9.

[0053] The following examples are used to verify the beneficial effects of the present invention:

[0054] Embodiment 1: The preparation method of an ultra-high strength aluminum alloy wire for aerospace fasteners in this embodiment is as follows:

[0055] 1. According to the mass percentage of elements: Cu: 2.15%, Mg: 2.20%, Zn: 8.1%, Zr: 0.12% and the balance is Al, weigh aluminum ingots, pure magnesium ingots, pure zinc ingots, electrolytic copper, aluminum-copper master alloy and AlZr3 master alloy as raw materials. In order to strictly control the content of iron and silicon impurities, use refined aluminum ingots for remelting (Al99.99). Add the weighed raw materials into the smelting furnace, the smelting temperature is 720℃~760℃, the smelting heating time is 2h~6h, and then refine to obtain aluminum liquid;

[0056] 2. Casting of aluminum alloy ingot: Cast the aluminum liquid obtained in step 1 at a casting temperature of 700°C to 735°C, a casting speed of 80 mm / min, a casting water pressure of 0.05 MPa, and a cooling water temperature of 16°C to obtain an aluminum alloy ingot with a diameter of 170 mm;

[0057] 3. Homogenization annealing of aluminum alloy ingot: the ingot obtained in step 2 is placed in a resistance heating furnace at a temperature of 430°C / 12h+470°C / 48h to obtain a homogenization annealed ingot;

[0058] 4. Sawing and turning: The surface oxide scale of the cast ingot is turned to obtain an aluminum alloy ingot with a diameter of 145 mm, which is then cut into cast rod ingots with a length of 5000 mm to obtain aluminum alloy rolling rough material.

[0059] 5. Preheating of aluminum alloy ingot: Load the aluminum alloy rolled rough ingot into a pusher-type resistance heating furnace, keep it warm at 410°C for 6 hours, and obtain the preheated aluminum alloy rolled rough ingot.

[0060] 6. Preparation of wire rod by rolling: placing the preheated aluminum alloy ingot in a hot rolling mill for rolling to obtain hot rolled wire rod;

[0061] 7. Intermediate annealing of wire: put the aluminum alloy wire obtained in step 6 into a resistance heating furnace, keep it at 404°C for 3 hours, cool it to below 200°C at a rate of 35°C per hour, then heat it to 232°C and keep it for 4 hours, then take it out of the furnace and air cool it;

[0062] 8. Cold drawing: The annealed aluminum alloy wire is cold drawn through a stretching full-diameter die under the condition of a deformation rate of 30.1%, and then annealing and cold drawing are repeated to obtain an aluminum alloy wire in a cold drawn state.

[0063] IX. Finished product annealing: the aluminum alloy wire obtained in step 8 is placed in a resistance heating furnace, kept at 404°C for 3 hours, cooled to below 200°C at a rate of 35°C per hour, then heated to 232°C and kept for 4 hours, then taken out of the furnace and air-cooled to obtain an aluminum alloy wire rod;

[0064] 10. Heat treatment: The wire is sampled and solution treated in a quenching furnace, kept at 450°C for 90 minutes, heated to 470°C for 120 minutes, and then quenched in water at 22°C to obtain quenched aluminum alloy wire; the quenched aluminum alloy wire is kept at 120°C for 6 hours, then heated to 160°C and kept for 7 hours to obtain T76 state aluminum alloy wire after aging treatment, that is, ultra-high strength aluminum alloy wire for aerospace fasteners.

[0065] In step 2, aluminum titanium boron wire is dotted into the casting of the aluminum alloy ingot, and the amount of aluminum titanium boron wire added is: the amount of Ti element dotted into the raw material is 0.005wt%.

[0066] Figure 1 This is a physical picture of the high-strength aluminum alloy wire for aerospace fasteners prepared in this embodiment; Figure 2 This is a physical picture of the ultra-high-strength MJ threaded bolt fastener product produced using high-strength aluminum alloy wire for aerospace fasteners;

[0067] Figure 3This is the microstructure diagram of the aluminum alloy ingot obtained in step 2; it can be seen from the figure that the dendrite structure of the ingot is evenly distributed, there is a non-equilibrium eutectic structure between the dendrites, and there are fewer precipitated phases in the crystal.

[0068] Figure 4 This is the metallographic structure of the annealed wire obtained after the finished product annealing in step nine; it can be seen from the figure that the wire grain structure is fine and uniform; Figure 5 This is the microstructure diagram of the T76 wire obtained in step 10. From the figure, the wire cross-section has a fine structure and no obvious coarse grain ring is seen on the edge.

[0069] Figure 6 This is a transmission photograph of the T76 wire obtained in step 10. It can be seen from the figure that the precipitation phase within the wire crystal is uniform and fine, and the precipitation phase at the grain boundary is discontinuously distributed in points, which can ensure both the high strength and high corrosion resistance of the wire.

[0070] The ultra-high strength aluminum alloy wire for fasteners produced by the present embodiment has a tensile strength of 675 MPa, a specified non-proportional elongation strength of greater than 642 MPa, an elongation after fracture of greater than 12.7%, and an electrical conductivity of 35.5% IACS.

[0071] Embodiment 2: The preparation method of an ultra-high strength aluminum alloy wire for aerospace fasteners in this embodiment is as follows:

[0072] 1. According to the mass percentage of the elements: Cu: 2.24%, Mg: 2.15%, Zn: 7.9%, Zr: 0.13% and the balance is Al, weigh aluminum ingots, pure magnesium ingots, pure zinc ingots, electrolytic copper, aluminum-copper master alloy and AlZr3 master alloy as raw materials. In order to strictly control the content of iron and silicon impurities, use refined aluminum ingots for remelting (Al99.99). Add the weighed raw materials to the smelting furnace, the smelting temperature is 720℃~760℃, the smelting heating time is 2h~6h, and then refine to obtain aluminum liquid; Add the weighed raw materials to the smelting furnace, the smelting temperature is 720℃~760℃, the smelting heating time is 2h~6h, and then refine to obtain aluminum liquid;

[0073] 2. Casting of aluminum alloy ingots: Casting the aluminum liquid obtained in step 1 at a casting temperature of 700° C. to 735° C., a casting speed of 70 mm / min, a casting water pressure of 0.04 MPa, and a cooling water temperature of 17° C. to obtain an aluminum alloy ingot with a diameter of 170 mm;

[0074] 3. Homogenization annealing of aluminum alloy ingot: the ingot obtained in step 2 is placed in a resistance heating furnace at a temperature of 430°C / 12h+470°C / 60h to obtain a homogenization annealed ingot;

[0075] 4. Sawing and turning: The surface oxide scale of the cast ingot is turned to obtain an aluminum alloy ingot with a diameter of 145 mm, which is then cut into a cast rod ingot with a length of 3800 mm to obtain an aluminum alloy rolling rough material.

[0076] 5. Preheating of aluminum alloy ingot: Load the aluminum alloy rolled rough ingot into a pusher-type resistance heating furnace, keep it warm at 420°C for 6 hours, and obtain the preheated aluminum alloy rolled rough ingot.

[0077] 6. Preparation of wire rod by rolling: placing the preheated aluminum alloy ingot in a hot rolling mill for rolling to obtain hot rolled wire rod;

[0078] 7. Intermediate annealing of wire: put the aluminum alloy wire obtained in step 6 into a resistance heating furnace, keep it at 404°C for 3 hours, cool it to below 200°C at a rate of 35°C per hour, then heat it to 232°C and keep it for 4 hours, then take it out of the furnace and air cool it;

[0079] 8. Cold drawing: The annealed aluminum alloy wire is cold drawn at a deformation rate of 29.2%, and then annealing and cold drawing are repeated to obtain an aluminum alloy wire in a cold drawn state.

[0080] IX. Finished product annealing: the aluminum alloy wire obtained in step 8 is placed in a resistance heating furnace, kept at 404°C for 3 hours, cooled to below 200°C at a rate of 35°C per hour, then heated to 232°C and kept for 4 hours, then taken out of the furnace and air-cooled to obtain an aluminum alloy wire rod;

[0081] 10. Heat treatment: The wire is sampled and solution treated in a quenching furnace, kept at 450°C for 90 minutes, heated to 470°C for 120 minutes, and then quenched in water at 22°C to obtain quenched aluminum alloy wire; the quenched aluminum alloy wire is kept at 120°C for 6 hours, then heated to 160°C and kept for 6.5 hours to obtain T76 state aluminum alloy wire after aging treatment, that is, ultra-high strength aluminum alloy wire for aerospace fasteners.

[0082] In step 2, aluminum titanium boron wire is dotted into the casting of the aluminum alloy ingot, and the amount of aluminum titanium boron wire added is: the amount of Ti element dotted into the raw material is 0.005wt%.

[0083] The ultra-high strength aluminum alloy wire for fasteners produced by the present embodiment has a tensile strength of 680 MPa, a non-proportional elongation strength of greater than 648 MPa, an elongation after fracture of greater than 12.5%, and an electrical conductivity of 35.2% IACS.

[0084] Embodiment 3: The method for preparing an ultra-high strength aluminum alloy wire for aerospace fasteners in this embodiment is as follows:

[0085] 1. According to the mass percentage of elements: Cu: 2.12%, Mg: 2.18%, Zn: 7.8%, Zr: 0.11% and the balance is Al, weigh aluminum ingots, pure magnesium ingots, pure zinc ingots, electrolytic copper, aluminum-copper master alloy and AlZr3 master alloy as raw materials, among which, in order to strictly control the content of iron and silicon impurities, use refined aluminum ingots for remelting (Al99.99). Add the weighed raw materials into the smelting furnace, the smelting temperature is 720℃~760℃, the smelting heating time is 2h~6h, and then refine to obtain aluminum liquid.

[0086] 2. Casting of aluminum alloy ingot: Cast the aluminum liquid obtained in step 1 at a casting temperature of 700°C to 735°C, a casting speed of 100 mm / min, a casting water pressure of 0.06 MPa, and a cooling water temperature of 18°C ​​to obtain an aluminum alloy ingot with a diameter of 170 mm;

[0087] 3. Homogenization annealing of aluminum alloy ingot: the ingot obtained in step 2 is placed in a resistance heating furnace at a temperature of 430°C / 10h+470°C / 50h to obtain a homogenization annealed ingot;

[0088] 4. Sawing and turning: The cast ingot blank is turned to remove the surface oxide scale to obtain an aluminum alloy ingot with a diameter of 145 mm, and then cut into a cast rod ingot with a length of 4700 mm to obtain an aluminum alloy rolling rough material.

[0089] 5. Preheating of aluminum alloy ingot: Load the aluminum alloy rolled rough ingot into a pusher-type resistance heating furnace, keep it warm at 415°C for 6 hours, and obtain the preheated aluminum alloy rolled rough ingot.

[0090] 6. Preparation of wire rod by rolling: placing the preheated aluminum alloy ingot in a hot rolling mill for rolling to obtain hot rolled wire rod;

[0091] 7. Intermediate annealing of wire: put the aluminum alloy wire obtained in step 6 into a resistance heating furnace, keep it at 404°C for 3 hours, cool it to below 198°C at a rate of 38°C per hour, then heat it to 232°C and keep it for 4 hours, then take it out of the furnace and air cool it;

[0092] 8. Cold drawing: The annealed aluminum alloy wire is cold drawn through a stretching full-diameter die under the condition of a deformation rate of 26.8%, and then annealing and cold drawing are repeated to obtain an aluminum alloy wire in a cold drawn state.

[0093] IX. Finished product annealing: the aluminum alloy wire obtained in step 8 is placed in a resistance heating furnace, kept at 404°C for 3 hours, cooled to below 198°C at a rate of 38°C per hour, then heated to 232°C and kept for 4 hours, then taken out of the furnace and air-cooled to obtain an aluminum alloy wire rod;

[0094] 10. Heat treatment: The wire is sampled and solution treated in a quenching furnace, kept at 450°C for 90 minutes, heated to 470°C for 120 minutes, and then quenched in water at 22°C to obtain quenched aluminum alloy wire; the quenched aluminum alloy wire is kept at 120°C for 6 hours, then heated to 160°C and kept for 6.5 hours to obtain T76 state aluminum alloy wire after aging treatment, that is, ultra-high strength aluminum alloy wire for aerospace fasteners.

[0095] In step 2, aluminum titanium boron wire is dotted into the casting of the aluminum alloy ingot, and the amount of aluminum titanium boron wire added is: the amount of Ti element dotted into the raw material is 0.005wt%.

[0096] The ultra-high-strength aluminum alloy wire for fasteners produced by this embodiment has a tensile strength of 641 MPa, a specified non-proportional elongation strength of greater than 602 MPa, an elongation after fracture of greater than 14.8%, and an electrical conductivity of 36.3% IACS.

Claims

1. A method for manufacturing ultra-high strength aluminum alloy wire for aerospace fasteners, characterized in that The manufacturing method is:

1. Melting of aluminum alloy ingots: weigh aluminum ingots, pure magnesium ingots, pure zinc ingots, electrolytic copper, aluminum-copper master alloy, and AlZr3 master alloy as raw materials according to the element mass percentage of Cu: 2.0% to 2.6%, Mg: 1.8% to 2.3%, Zn: 7.6% to 8.4%, Zr: 0.12% to 0.20% and the balance is Al; add the weighed raw materials into a smelting furnace, the smelting temperature is 720°C to 760°C, the smelting heating time is 2h to 6h, and then refine to obtain aluminum liquid; 2. Casting of aluminum alloy ingots: Cast the aluminum liquid obtained in step 1 at a casting temperature of 700°C to 735°C, a casting speed of 60mm / min to 100mm / min, a casting water pressure of 0.04MPa to 0.07MPa, and a cooling water temperature of 15°C to 25°C to obtain an aluminum alloy ingot with a diameter of 170mm; 3. Homogenizing annealing of the aluminum alloy ingot: placing the ingot obtained in step 2 into a resistance heating furnace for homogenizing annealing to obtain a homogenizing annealed ingot; 4. Sawing and lathing: The surface oxide scale of the homogenized annealed ingot is removed by lathing to obtain an aluminum alloy ingot with a diameter of 145 mm to 162 mm, which is then cut into cast rod ingots with a length of 3000 mm to 5500 mm to obtain an aluminum alloy rolled rough ingot; 5. Preheating of aluminum alloy ingot: Load the aluminum alloy rolled rough ingot into a pusher-type resistance heating furnace, keep it warm for 2h to 6h at a temperature of 390°C to 430°C, and obtain the preheated aluminum alloy rolled rough ingot; 6. Preparation of wire rod by rolling: placing the preheated aluminum alloy rolled raw material ingot in a hot rolling mill for rolling to obtain hot rolled wire rod; 7. Intermediate annealing of the wire: the hot-rolled wire obtained in step 6 is placed in a resistance heating furnace, kept at 404°C for 3 hours, cooled to below 200°C at a rate of 35°C per hour, then heated to 232°C and kept for 4 hours, then taken out of the furnace and air-cooled to obtain annealed aluminum alloy wire; 8. Cold drawing: cold drawing the annealed aluminum alloy wire under the condition of deformation rate of 25% to 45%, and then repeating annealing and cold drawing to obtain the aluminum alloy wire in cold drawing state; IX. Finished product annealing: put the cold drawn aluminum alloy wire into a resistance heating furnace, keep it at 404°C for 3 hours, cool it to below 200°C at a rate of 35°C per hour, then heat it to 232°C and keep it for 4 hours, then take it out of the furnace and air cool it to obtain aluminum alloy wire rods; 10. The aluminum alloy wire rod is subjected to solution treatment, quenching and aging treatment in a quenching furnace to obtain ultra-high strength aluminum alloy wire for aerospace fasteners.

2. The method for manufacturing an ultra-high strength aluminum alloy wire for aerospace fasteners according to claim 1, characterized in that: In step 1, a mixed gas of argon and chlorine is used for refining for 20 to 40 minutes. The mixed gas of argon and chlorine is a mixture of 96% argon and 4% chlorine by molar volume.

3. The method for manufacturing an ultra-high strength aluminum alloy wire for aerospace fasteners according to claim 1, characterized in that: In step 3, the homogenization annealing is first carried out at 430° C. for 8 h to 12 h, and then at 470° C. for 48 h to 60 h.

4. The method for manufacturing an ultra-high strength aluminum alloy wire for aerospace fasteners according to claim 1, characterized in that: The solid solution in step ten is carried out at a temperature of 450° C. and kept for 60 min to 120 min, and then the temperature is raised to 470° C. and kept for 90 min to 180 min.

5. The method for manufacturing an ultra-high strength aluminum alloy wire for aerospace fasteners according to claim 1, characterized in that: The quenching in step 10 is quenching in water at a temperature of 0°C to 35°C.

6. The method for manufacturing an ultra-high strength aluminum alloy wire for aerospace fasteners according to claim 1, characterized in that: The aging treatment in step ten is as follows: the quenched aluminum alloy wire is kept at a temperature of 117° C. to 123° C. for 4 h to 10 h, and then the temperature is raised to 157° C. to 163° C. and kept at this temperature for 4 h to 10 h.

7. The method for manufacturing an ultra-high strength aluminum alloy wire for aerospace fasteners according to claim 1, characterized in that: Step eight: cold stretching through a stretching and sizing die.

8. The method for manufacturing an ultra-high strength aluminum alloy wire for aerospace fasteners according to claim 1, characterized in that: The tensile strength of aluminum alloy wire for high-performance aerospace fasteners reaches 630MPa~680MPa, the specified non-proportional elongation strength reaches 590MPa~620MPa, the elongation after fracture is greater than 10.0%, and the electrical conductivity is greater than 35% IACS.

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