Preparation method and application of aluminum alloy wire

Abstract

The invention discloses a preparation method and application of an aluminum alloy wire, and belongs to the technical field of aluminum alloy processing. The preparation method of the aluminum alloy wire provided by the invention comprises the following steps: S1, carrying out annealing treatment on a blank; the temperature of the annealing treatment is 350-440 DEG C; s2, rotary forging; in the rotary forging process, the rotating speed of a forging hammer is 100-400 rpm, and the feeding speed is 30-80 mm / s; s3, heat treatment; the heat treatment temperature is 460-480 DEG C, and the heating speed is greater than or equal to 60 DEG C / min; and S4, artificial aging treatment. According to the preparation method of the aluminum alloy wire, a bimodal distribution grain structure can be obtained in the aluminum alloy wire, and then the strength and elongation performance of the aluminum alloy wire are considered; and the yield of the aluminum alloy wire can be improved. The invention also provides application of the preparation method.

Description

Technical Field

[0001] This invention relates to the field of aluminum alloy processing technology, and in particular to a method for preparing aluminum alloy wire and its application. Background Technology

[0002] With the continuous development of productivity, fasteners are gradually evolving towards more advanced and refined products to meet the working requirements of various harsh environments. Because aluminum alloys are characterized by low density, good plasticity, and certain corrosion resistance, lightweight, high-strength aluminum alloys are ideal materials for manufacturing fasteners for aerospace and other applications. In fastener manufacturing, aluminum alloy wire is often uptaken, requiring the blank to have excellent plasticity.

[0003] Compared to aluminum alloys with a single-grain structure, aluminum alloys with a bimodal grain structure exhibit higher strength and ductility: fine grains contribute to increased strength, while coarse grains effectively accumulate dislocations, resulting in a high work hardening rate. Simultaneously, coarse grains can induce localized deformation under stress concentration, creating localized passivation that inhibits crack propagation and improves ductility. Currently, methods for obtaining a bimodal grain structure in aluminum alloys mainly include cumulative rolling, powder synthesis, equal-channel corner extrusion, and a combination of multiple-pass annealing. These methods are difficult to employ in the preparation of aluminum alloy wires or are too inefficient. Currently, there are three main processing methods for aluminum alloy fastener wires: extrusion-drawing, continuous casting-rolling-drawing, and Y-mill rolling. These methods, combined with traditional technical parameters, struggle to achieve a bimodal grain structure in aluminum alloy wires; therefore, while the strength of the resulting aluminum alloy wires may meet the requirements, the elongation is relatively low. Summary of the Invention

[0004] This invention aims to at least solve one of the technical problems existing in the prior art. To this end, this invention proposes a method for preparing aluminum alloy wire, which can obtain a bimodal grain structure in the aluminum alloy wire, thereby taking into account both the strength and elongation properties of the aluminum alloy wire; it can also improve the yield of the aluminum alloy wire.

[0005] The present invention also provides applications of the above preparation method.

[0006] According to an embodiment of the first aspect of the present invention, a method for preparing aluminum alloy wire is provided, the method comprising the following steps: S1. Anneal the billet; the annealing temperature is 350~440℃; S2. The product obtained from the rotary forging step S1; during the rotary forging process, the forging hammer rotation speed is 100~400rpm and the feed speed is 30~80mm / s; S3. The product obtained from heat treatment step S2 is then quenched; the heat treatment temperature is 460~480℃, and the heating rate is ≥60℃ / min; S4. Perform artificial aging treatment on the product obtained in step S3.

[0007] The preparation method according to embodiments of the present invention has at least the following beneficial effects: The annealing treatment in step S1, by selecting an appropriate annealing temperature, can obtain a micron-sized second phase with a reasonable size and fraction, while improving the forgeability of the billet and laying the foundation for subsequent rotary forging. In the rotary forging in step S2, by controlling the rotation speed and feed speed, the cross-section of the billet can be reduced while forming high-density dislocations around the micron-sized second phase. In the heat treatment in step S3, particle-induced nucleation promotes the preferential nucleation and growth of some recrystallized grains, while recrystallized grains in other areas nucleate later. Through reasonable control of time and temperature, a bimodal grain structure is obtained, achieving a match between high strength and high elongation. In step S4, artificial aging after quenching obtains a high-density nano-sized precipitated strengthening phase, further improving the comprehensive properties such as strength and elongation.

[0008] Furthermore, the present invention uses a rotary forging method to deform aluminum alloy materials. The resulting aluminum alloy wire is in a triaxial compressive stress state, which can better exert the plasticity of the material. There is no need for heat treatment between passes, and continuous multi-pass rotary forging can be performed. Moreover, a single rotary forging can achieve the maximum cross-sectional compression ratio, thereby greatly shortening the production cycle (20-40% shorter than drawing) and reducing production costs.

[0009] Furthermore, compared to the drawing method, the rotary forging method is less likely to produce defects such as scratches and cracks on the wire surface during the preparation process; the roughness of the resulting aluminum alloy wire can reach 1.6μm or even lower.

[0010] In summary, the preparation method provided by this invention can obtain a bimodal grain structure in aluminum alloy wire through the synergistic effect of multiple steps and parameters, thereby enabling it to simultaneously achieve high strength and high elongation.

[0011] According to some embodiments of the present invention, the blank is made of 7-series aluminum alloy. For example, it can be 7055 aluminum alloy or 7075 aluminum alloy.

[0012] According to some embodiments of the present invention, the billet is an extruded billet. The extrusion process can improve the density of the billet, eliminate defects, and is more conducive to subsequent rotary forging, thus contributing to the improvement of the overall performance of the resulting aluminum alloy wire.

[0013] According to some embodiments of the present invention, in step S1, the annealing temperature is 350~440℃. For example, it can be 350℃, 360℃, 370℃, 380℃, 390℃, 400℃, 410℃, 420℃, 430℃, 440℃; or a range of values ​​composed of any two of the above points.

[0014] According to some embodiments of the present invention, in step S1, the holding time for the annealing treatment is 0.5 to 2 hours. For example, it can be 0.5 hours, 1 hour, 1.5 hours, 2 hours; or a range of values ​​composed of any two of the above points.

[0015] According to some embodiments of the present invention, in step S1, the cooling method after annealing includes air cooling. That is, after being removed from the heating furnace, it is allowed to cool naturally in the air.

[0016] According to some embodiments of the present invention, in step S2, the forging frequency of the rotary forging is 700 to 3000 times / min. For example, it can specifically be 700 times / min, 1000 times / min, 1200 times / min, 1300 times / min, 1500 times / min, 1600 times / min, 1900 times / min, 2000 times / min, 2200 times / min, 2500 times / min, 2800 times / min, 3000 times / min; or a range of values ​​composed of any two of the above points.

[0017] According to some embodiments of the present invention, in step S2, the single reduction amount of the rotary forging is 0.1~2mm. Specifically, it can be 0.1mm, 0.2mm, 0.3mm, 0.4mm, 0.5mm, 0.6mm, 0.7mm, 0.8mm, 0.9mm, 1.0mm, 1.1mm, 1.2mm, 1.3mm, 1.4mm, 1.5mm, 1.6mm, 1.7mm, 1.8mm, 1.9mm, or 2.0mm; or a range of values ​​formed by any two of the above points. In this invention, the single reduction amount represents the reduction in diameter during one rotary forging operation.

[0018] Within this range, defects and cracks can be significantly avoided, ensuring the smooth progress of rotary forging.

[0019] In actual production, the number of rotary forging operations can be calculated based on the above-mentioned single pressing amount, the size of the billet, and the design dimensions of the aluminum alloy wire.

[0020] According to some embodiments of the present invention, in step S2, during the rotary forging process, the rotation speed of the forging hammer is 100~400 rpm. For example, it can be 100 rpm, 150 rpm, 200 rpm, 250 rpm, 300 rpm, 350 rpm, 400 rpm; or a range of values ​​composed of any two of the above points.

[0021] According to some embodiments of the present invention, in step S2, during the rotary forging process, the feed speed is 30~80 mm / s. For example, it can be 30 mm / s, 40 mm / s, 50 mm / s, 60 mm / s, 70 mm / s, 80 mm / s; or a range of values ​​composed of any two of the above points.

[0022] According to some embodiments of the present invention, in step S2, the final temperature of the rotary forging is 20~60°C. Specifically, it can be 20°C, 25°C, 30°C, 35°C, 40°C, 45°C, 50°C, 55°C, or 60°C; or a range of any two of the above values. To achieve the above temperature, lubrication cooling is applied during the rotary forging process, thereby preventing grain growth introduced by deformation heat, preventing the generation of defects and cracks, and facilitating die lubrication.

[0023] According to some embodiments of the present invention, in step S3, the heating rate of the heat treatment is ≥60℃ / min. For example, it can be 60℃ / min, 65℃ / min, 70℃ / min, or a range of values ​​composed of any two of the above points.

[0024] According to some embodiments of the present invention, in step S3, the temperature of the heat treatment is 460~480℃. For example, it can be 460℃, 465℃, 470℃, 475℃, 480℃; or a range of values ​​composed of any two of the above points.

[0025] According to some embodiments of the present invention, in step S3, the holding time for reaching the target temperature during heat treatment is 5 to 20 minutes. Specifically, it can be 5 minutes, 8 minutes, 10 minutes, 12 minutes, 15 minutes, or 20 minutes; or a range of values ​​composed of any two of the above points. The holding time for reaching the target temperature refers to the holding time after the temperature has risen to the target temperature.

[0026] According to some embodiments of the present invention, in step S3, the quenching method includes room temperature water quenching.

[0027] According to some embodiments of the present invention, in step S4, the artificial aging process includes sequentially performing a first-level aging process and a second-level aging process.

[0028] According to some embodiments of the present invention, the temperature for the first-stage aging is 60~80℃. For example, it can specifically be 60℃, 65℃, 70℃, 75℃, 80℃; or a range of values ​​composed of any two of the above points.

[0029] According to some embodiments of the present invention, the holding time for the first-stage aging process is 10-16 hours. For example, it can be 10 hours, 11 hours, 12 hours, 13 hours, 14 hours, 15 hours, or 16 hours; or a range of values ​​composed of any two of the above points.

[0030] According to some embodiments of the present invention, the temperature for the secondary aging process is 120~140℃. For example, it can specifically be 120℃, 125℃, 130℃, 135℃, 140℃; or a range of values ​​consisting of any two of the above points.

[0031] According to some embodiments of the present invention, the holding time for the secondary aging process is 10~24h. For example, it can be 10h, 11h, 12h, 13h, 14h, 15h, 16h, 17h, 18h, 19h, 20h, 21h, 22h, 23h, 24h; or a range of values ​​composed of any two of the above points.

[0032] According to an embodiment of the second aspect of the present invention, the application of the preparation method of the first aspect of the present invention in the preparation of fasteners for aerospace equipment and new energy vehicles is provided.

[0033] Since the application adopts all the technical solutions of the preparation method of the above embodiments, it has at least all the beneficial effects brought about by the technical solutions of the above embodiments.

[0034] Other features and advantages of the invention will be set forth in the description which follows, and will be apparent in part from the description, or may be learned by practicing the invention. Attached Figure Description

[0035] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which: Figure 1 This is an appearance diagram of the product obtained in step S2 of Embodiment 1 of the present invention.

[0036] Figure 2 This is the appearance of the fractured billet during the rotary forging process of Comparative Example 1 of the present invention.

[0037] Figure 3 This is the appearance of the aluminum alloy wire obtained in Comparative Example 2 of the present invention.

[0038] Figure 4 This is a cross-sectional metallographic image of the aluminum alloy wire obtained in Comparative Example 3 of this invention.

[0039] Figure 5 This is a cross-sectional metallographic image of the aluminum alloy wire obtained in Embodiment 2 of the present invention. Detailed Implementation

[0040] The following will describe the concept and technical effects of the present invention clearly and completely with reference to embodiments, so as to fully understand the purpose, features and effects of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are all within the scope of protection of the present invention.

[0041] Example 1 This example demonstrates the preparation of an aluminum alloy wire. The specific preparation steps are as follows: S1. Raw material preparation: Select 7055 aluminum alloy extrusion billets with chemical composition that meet the standards, and cut them into billets with a length of 500mm.

[0042] Annealing: Place the billet in a heating furnace, heat to 430℃, hold for 1 hour, and then air cool to room temperature.

[0043] S2. Rotary Forging: The annealed billet is forged using a rotary forging machine. The rotation speed is set to 200 rpm, the forging frequency to 1440 times / min, and the axial feed speed to 30 mm / s. The final forging temperature is controlled at approximately 40℃. After six rotary forging passes, each reducing the diameter by 1 mm, the billet diameter is reduced from the initial 12 mm to 6 mm. Lubrication and cooling are applied simultaneously during rotary forging. Good surface quality is achieved, such as... Figure 1 As shown.

[0044] S3. Final heat treatment: The product obtained in step S2 is subjected to rapid heating and short-time high-temperature solution treatment, followed by room temperature water quenching. The solution temperature is 470℃, the heating rate is 65℃ / min, and the temperature is held for 10min after reaching the set temperature.

[0045] S4. Artificial aging treatment: The mechanism of artificial aging is as follows: first, keep warm at 80℃ for 12 hours, then raise the temperature to 120℃ and keep warm for another 16 hours.

[0046] Example 2 This example demonstrates the preparation of an aluminum alloy wire. The specific preparation steps are as follows: S1. Raw material preparation: Select 7075 aluminum alloy extrusion billets that meet the requirements and cut them into 600mm long segments.

[0047] Annealing: Place the billet in a heating furnace, heat to 380℃, hold for 1.5 hours, and cool to room temperature in air.

[0048] S2. Rotary Forging: The annealed billet is forged using a rotary forging machine. The rotation speed is set to 180 rpm, the forging frequency to 1296 times / min, the feed rate to 50 mm / s, and the final forging temperature to be controlled at approximately 30℃. After 10 rotary forgings, with a diameter reduction of 0.7 mm each time, the diameter of the billet is reduced from 12 mm to 5 mm.

[0049] S3. Final heat treatment: The product after rotary forging is subjected to high-temperature short-time solution treatment followed by room temperature water quenching. The solution temperature is 475℃, the heating rate is 60℃ / min, and the temperature is held for 8min after reaching the solution temperature. S4. Artificial aging treatment: The mechanism of artificial aging is as follows: first, keep warm at 75℃ for 14 hours, then raise the temperature to 130℃ and keep warm for 12 hours.

[0050] Comparative Example 1 This example prepares an aluminum alloy wire, which differs from Example 2 in that: In step S1, the heating temperature is 465℃.

[0051] The specific preparation steps are as follows: S1. Raw material preparation: Select 7075 aluminum alloy extrusion billets that meet the requirements and cut them into 600mm long segments.

[0052] Annealing: Place the billet in a heating furnace, heat to 465℃, hold for 1.5 hours, and cool to room temperature in air.

[0053] S2. Rotary Forging: The annealed billet is forged using a rotary forging machine. The rotation speed is set to 180 r / min, the forging frequency to 1296 times / min, the feed rate to 50 mm / s, and the final forging temperature to be controlled at approximately 30℃. After 10 rotary forgings, with a diameter reduction of 0.7 mm each time, the diameter of the billet is reduced from 12 mm to 5 mm.

[0054] S3. Final heat treatment: The product after rotary forging is subjected to high-temperature short-time solution treatment followed by room temperature water quenching. The solution temperature is 475℃, the heating rate is 60℃ / min, and the temperature is held for 8min after reaching the solution temperature. S4. Artificial aging treatment: The mechanism of artificial aging is as follows: first, keep warm at 75℃ for 14 hours, then raise the temperature to 130℃ and keep warm for 12 hours.

[0055] The results showed that the process cracked during the second rotary forging from 12mm, making it impossible to continue.

[0056] During rotary forging, the appearance of the fractured billet is as follows: Figure 2 As shown.

[0057] Comparative Example 2 This example prepares an aluminum alloy wire, which differs from Example 2 in that: In step S2, the rotational speed of the rotary forging is 450 rpm and the feed rate is 20 mm / s.

[0058] The specific preparation steps are as follows: S1. Raw material preparation: Select 7075 aluminum alloy extrusion billets that meet the requirements and cut them into 600mm long segments.

[0059] Annealing: Place the billet in a heating furnace, heat to 380℃, hold for 1.5 hours, and cool to room temperature in air.

[0060] S2. Rotary Forging: The annealed billet is forged using a rotary forging machine. The rotation speed is set to 450 rpm, the forging frequency to 1296 times / min, the feed rate to 20 mm / s, and the final forging temperature to be controlled at approximately 30℃. After 10 rotary forgings, with a diameter reduction of 0.7 mm each time, the diameter of the billet is reduced from 12 mm to 5 mm.

[0061] S3. Final heat treatment: The product after rotary forging is subjected to high-temperature short-time solution treatment followed by room temperature water quenching. The solution temperature is 475℃, the heating rate is 60℃ / min, and the temperature is held for 8min after reaching the solution temperature. S4. Artificial aging treatment: The mechanism of artificial aging is as follows: first, keep warm at 75℃ for 14 hours, then raise the temperature to 130℃ and keep warm for 12 hours.

[0062] Comparative Example 3 This example prepares an aluminum alloy wire, which differs from Example 2 in that: In step S3, the solid solution is heated to 475°C over 1 hour.

[0063] The specific preparation steps are as follows: S1. Raw material preparation: Select 7075 aluminum alloy extrusion billets that meet the requirements and cut them into 600mm long segments.

[0064] Annealing: Place the billet in a heating furnace, heat to 380℃, hold for 1.5 hours, and cool to room temperature in air.

[0065] S2. Rotary Forging: The annealed billet is forged using a rotary forging machine. The rotation speed is set to 180 r / min, the forging frequency to 1296 times / min, the feed rate to 50 mm / s, and the final forging temperature to be controlled at approximately 30℃. After 10 rotary forgings, with a diameter reduction of 0.7 mm each time, the diameter of the billet is reduced from 12 mm to 5 mm.

[0066] S3. Final heat treatment: The product after rotary forging is subjected to high-temperature short-time solution treatment followed by room temperature water quenching. The solution temperature is 475℃, the heating rate is 1h to 475℃, and the temperature is held for 8min after reaching the temperature. S4. Artificial aging treatment: The mechanism of artificial aging is as follows: first, keep warm at 75℃ for 14 hours, then raise the temperature to 130℃ and keep warm for 12 hours.

[0067] Test case This example tested the appearance, tensile strength, yield strength, elongation at break, and cross-sectional metallographic images of the aluminum alloy wires obtained in the examples and comparative examples. Appearance was assessed visually. The tensile strength, yield strength, and elongation were tested using room temperature tensile testing according to GB / T 16865. Grain size was tested using the intercept method in GB / T 3246.1, measured in the metallographic image, with ≥100 grains measured in a single measurement. The test results are as follows: Figures 1-5 As shown in Table 1, three samples were tested in parallel for each embodiment, and the test results were taken as the average value or the statistical result range.

[0068] Table 1. Performance of aluminum alloy wires obtained in the examples and comparative examples

[0069] In Table 1, "~" indicates approximate, and batch test data fluctuates within ±2%.

[0070] Appearance tests showed that the aluminum alloy wire obtained in Example 1 had a bright surface and good quality; the aluminum alloy wire obtained in Example 2 was comparable to that in Example 1; the surface roughness of the obtained aluminum alloy wire was ≤1.6μm. Comparative Example 1 broke during the preparation process, and no complete aluminum alloy wire was obtained. The aluminum alloy wire obtained in Comparative Example 2 had an uneven surface, powdery texture, and peeling, indicating poor quality and an appearance as shown. Figure 3 As shown. The surface quality of the aluminum alloy wire prepared in Comparative Example 3 is also good, comparable to that in Example 2.

[0071] Metallographic and mechanical property test results show that: Within the scope of this invention, aluminum alloy wires with bimodal grain distribution and excellent tensile strength, yield strength, and elongation can be obtained. Due to these advantages, the obtained aluminum alloy wires are expected to be used in the preparation of fasteners for aerospace equipment and new energy vehicles. However, it should also be noted that changing the parameters within the scope of this invention will also lead to differences in the results of the aluminum alloy wires. For example, within the parameter range, if the single-pass reduction and rotation speed of rotary forging are reduced while the feed rate is increased, the degree of hammering received by the intermediate billet decreases, and the dislocation density will decrease to some extent. Therefore, in the final aluminum alloy wire, the grain size of both large and small grains will decrease to some extent, and consequently, the mechanical properties will also decrease to some extent. In other words, in actual production, if the feed rate is too fast, one or more rotary forging operations are required to fully deform the billet. That is to say, within the parameter range provided by this invention, changing one parameter while simultaneously optimizing other parameters can still yield aluminum alloy wires with good performance. The aluminum alloy wire obtained in the example clearly exhibits a distribution of two grain sizes; this allows for both increased strength and increased elongation. The metallographic examination results of Example 2 are as follows... Figure 5 As shown.

[0072] Comparative Example 1 fractured during rotary forging, and the appearance of the aluminum alloy wire obtained in Comparative Example 2 was clearly unsatisfactory; therefore, its mechanical properties and grain size were not characterized.

[0073] In the aluminum alloy wire obtained in Comparative Example 3, coarse grains appeared on the surface, without a clear bimodal grain distribution, which is not conducive to obtaining high strength and high elongation; metallographic test results are as follows. Figure 4 As shown.

[0074] The embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the above embodiments, and various changes can be made within the scope of knowledge possessed by those skilled in the art without departing from the spirit of the present invention. Furthermore, the embodiments of the present invention and the features thereof can be combined with each other unless otherwise specified.

Claims

1. A method for preparing aluminum alloy wire, characterized in that, The preparation method includes the following steps: S1. Anneal the billet; the annealing temperature is 350~440℃; S2. The product obtained from the rotary forging step S1; during the rotary forging process, the forging hammer rotation speed is 100~400rpm and the feed speed is 30~80mm / s; S3. The product obtained from heat treatment step S2 is then quenched; the heat treatment temperature is 460~480℃, and the heating rate is ≥60℃ / min; S4. Perform artificial aging treatment on the product obtained in step S3.

2. The preparation method according to claim 1, characterized in that, The blank is made of 7-series aluminum alloy.

3. The preparation method according to claim 1, characterized in that, In step S1, the holding time for the annealing treatment is 0.5~2h.

4. The preparation method according to claim 1, characterized in that, In step S2, the single reduction amount of the rotary forging is 0.1~2mm.

5. The preparation method according to claim 1, characterized in that, In step S2, the final temperature of the rotary forging is 20~60℃.

6. The preparation method according to claim 1, characterized in that, In step S3, the heat treatment holding time is 5~20 min; and / or, in step S3, the quenching method includes water quenching.

7. The preparation method according to claim 1, characterized in that, In step S4, the manual timeliness processing includes first-level timeliness and second-level timeliness performed sequentially.

8. The preparation method according to claim 7, characterized in that, The temperature for the first-stage aging is 60~80℃; and / or the holding time for the first-stage aging is 10~16h.

9. The preparation method according to claim 7, characterized in that, The temperature for the secondary aging process is 120~140℃; and / or the holding time for the secondary aging process is 10~24h.

10. The application of the preparation method as described in any one of claims 1 to 9 in the preparation of fasteners for aerospace equipment and new energy vehicles.

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