Aluminum alloy and method for manufacturing the same

Abstract

The application discloses an aluminum alloy and a preparation method thereof, wherein the steps of the method include casting, face milling, homogenization treatment, hot rolling, first cold rolling, recrystallization annealing and synergistic treatment in sequence; the reduction of the first cold rolling is greater than or equal to 60%; the synergistic treatment includes second cold rolling and recovery annealing; the reduction of the second cold rolling is 10-30%, and the second cold rolling includes multiple cold rolling passes, and the reduction of each cold rolling pass is 2-5%; the number of recovery annealing is less than the number of cold rolling passes by one time, the temperature of recovery annealing is 70-120 DEG C, and the time of each recovery annealing is 1-4h. The yield strength of the aluminum alloy prepared by the preparation method is greater than or equal to 360MPa, and the aluminum alloy can bear bending with a bending angle of 90 DEG and a bending inner radius of 0.5mm without cracking, that is, the high strength and high bending performance of the aluminum alloy can be simultaneously considered.

Description

Technical Field

[0001] This invention relates to the field of aluminum processing technology, and in particular to a 5-series aluminum alloy and its preparation method. Background Technology

[0002] 5-series aluminum alloys (i.e., aluminum-magnesium alloys) have become key materials in fields such as shipbuilding and marine engineering, lightweight components for automobiles and rail transportation, and consumer electronics housings due to their excellent corrosion resistance, good weldability and formability, and outstanding surface treatment effects.

[0003] In related technologies, 5-series aluminum alloys, as typical non-heat-treatable strengthened aluminum alloys, rely mainly on solid solution strengthening and work hardening for their strength. However, with the continuous improvement of the requirements for material strength, achieving this goal often relies heavily on the degree of work hardening, mainly through cold rolling. This significantly reduces the bending performance of the material, making it prone to cracking during subsequent processing. This contradiction is particularly evident in specific production processes.

[0004] Specifically, improving the strength of 5-series aluminum alloys mainly relies on increasing the cold rolling reduction rate to enhance work hardening. This method increases work hardening by increasing dislocation density. While this effectively strengthens the material, excessively high dislocation density can lead to severe dislocation pile-up and entanglement, resulting in highly uneven micro-strain distribution within the material. This can easily lead to strain concentration in localized areas, causing the material to fracture during bending. Therefore, if strength is improved solely by increasing dislocation density while neglecting the uniformity of strain distribution within the material, it is often difficult to achieve both high strength and high bending performance.

[0005] Therefore, there is an urgent need for a new aluminum alloy and its preparation method to solve the above problems. Summary of the Invention

[0006] The purpose of this invention is to provide a new aluminum alloy and its preparation method, in order to solve the problem in the related art that the 5-series aluminum alloys cannot simultaneously achieve high strength and high bending performance by only increasing the reduction rate of cold rolling to increase their work hardening degree.

[0007] In a first aspect, embodiments of the present invention provide a method for preparing an aluminum alloy, the steps of which sequentially include casting, milling, homogenization treatment, hot rolling, first cold rolling, recrystallization annealing, and co-processing; the reduction rate of the first cold rolling is greater than or equal to 60%; the co-processing includes a second cold rolling and recovery annealing; the reduction rate of the second cold rolling is 10-30%, the second cold rolling includes multiple cold rolling passes, and the reduction rate of each cold rolling pass is 2-5%; the number of recovery annealing passes is one less than the number of cold rolling passes, and except for the last cold rolling pass, a recovery annealing is performed after each cold rolling pass, the recovery annealing temperature is 70-120℃, and the recovery annealing time is 1-4 hours.

[0008] Preferably, the second cold rolling includes 2 to 6 cold rolling passes; the recovery annealing includes 1 to 5 passes.

[0009] Preferably, the final rolling temperature of hot rolling is 300~350℃.

[0010] Preferably, the recrystallization annealing temperature is 250~450℃, and the recrystallization annealing time is 10~20h.

[0011] Preferably, the grain size of the aluminum material after recrystallization annealing is 5~20μm.

[0012] Preferably, the yield strength of the aluminum material decreases by 2~20MPa after each recovery annealing.

[0013] Preferably, the average dislocation density of the aluminum alloy obtained after co-processing is 2×10⁻⁶. 14 ~20×10 14 m -2 .

[0014] Preferably, the average nucleus orientation difference of the aluminum alloy obtained after co-processing is 0.5~2.0°, the standard value of the average nucleus orientation difference is 0.1~0.4°, the value range of the average nucleus orientation difference is 0.5~2.5°, and the ratio of the average nucleus orientation difference to the maximum orientation difference is 5~30%.

[0015] Secondly, embodiments of the present invention provide an aluminum alloy, which is made by the above-described method for preparing aluminum alloys.

[0016] Compared with related technologies, the aluminum alloy preparation method of this invention firstly designs the reduction rate of the first cold rolling to be greater than or equal to 60%, which introduces higher deformation energy into the aluminum material. This improves the nucleation rate during the subsequent recrystallization annealing process, resulting in a finer and more uniform grain structure, thus laying a crucial microstructural foundation for achieving a uniform micro-strain distribution in the aluminum alloy. Secondly, by distributing the total reduction rate of the second cold rolling across multiple cold rolling passes, a high dislocation density is accumulated to fully obtain the dislocation strengthening effect, while effectively avoiding the problems of dislocation entanglement and uneven micro-strain distribution caused by excessive deformation in a single pass. Finally, combined with recovery annealing at a temperature of 70~120℃, dislocation rearrangement and annihilation can be further promoted to improve the uniformity of micro-strain distribution. The aluminum alloy prepared by the method of this invention has a yield strength greater than or equal to 360MPa and can withstand a bending angle of 90° and an inner bending radius of 0.5mm without cracking, thus simultaneously achieving high strength and high bending performance of the aluminum alloy. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort, wherein: Figure 1 This is a schematic flowchart illustrating the steps of an aluminum alloy preparation method provided in an embodiment of the present invention. Detailed Implementation

[0018] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0019] Example 1 This invention provides a method for preparing an aluminum alloy, combined with... Figure 1 As shown, the steps are as follows: S1, casting; S2, milling; S3, homogenization treatment; S4, hot rolling; S5, first cold rolling; S6, recrystallization annealing; S7, co-processing.

[0020] The final rolling temperature for hot rolling is 300~350℃.

[0021] The reduction rate of the first cold rolling is greater than or equal to 60%. By increasing the reduction rate of the first cold rolling, higher deformation energy can be introduced into the aluminum material. In the subsequent recrystallization annealing process, the nucleation rate can be increased through higher deformation energy storage, thereby obtaining a finer and more uniform grain structure. This fine and uniform grain structure (microstructure) lays a key microstructural foundation for achieving a uniform micro-strain distribution in the final aluminum alloy.

[0022] The recrystallization annealing temperature is 250~450℃, and the recrystallization annealing time is 10~20h; By combining the reduction rate limit of the first cold rolling and the parameter design of recrystallization annealing, the grain size of the aluminum material after recrystallization annealing can be 5~20μm, thus obtaining a finer and more uniform grain structure.

[0023] The co-processing includes a second cold rolling and recovery annealing.

[0024] The reduction rate of the second cold rolling is 10-30%, and the second cold rolling includes multiple cold rolling passes, with a reduction rate of 2-5% for each cold rolling pass. Compared with single-pass large deformation cold rolling, by distributing the total deformation (reduction rate) across multiple cold rolling passes, it is possible to accumulate a high dislocation density to fully obtain the dislocation strengthening effect, while effectively avoiding the problems of local dislocation entanglement and uneven micro-strain distribution caused by excessive deformation in a single pass.

[0025] The number of recovery annealing passes is one less than the number of cold rolling passes. Except for the last cold rolling pass, recovery annealing is performed after each cold rolling pass. The recovery annealing temperature is 70~120℃, and the recovery annealing time is 1~4h. The design of recovery annealing combined with the second cold rolling after multiple cold rolling passes can further promote dislocation rearrangement and annihilation, thereby improving the uniformity of micro-strain distribution.

[0026] The temperature of each recovery annealing is controlled at 70~120℃. The purpose of this low-temperature treatment is to promote the orderly rearrangement of dislocations, but it is not enough to trigger large-scale dislocation annihilation. Thus, the goal of optimizing the dislocation structure is achieved while maintaining a high dislocation density, rather than significantly reducing the dislocation density. The yield strength of the aluminum material decreases by 2~20MPa after each recovery annealing.

[0027] In this embodiment, the second cold rolling includes 2 to 6 cold rolling passes; the recovery annealing includes 1 to 5 passes.

[0028] The synergistic treatment not only maximizes the role of dislocation strengthening but also enables precise control of the critical value of strengthening contribution, thus establishing a better synergistic relationship between strength and bending performance; the average dislocation density of the aluminum alloy obtained after synergistic treatment ( ρ The range of ) is: ρ= 2×10 14 ~20×10 14 m -2 Among them, the critical strength provided by dislocation strengthening is 150~200MPa.

[0029] The average nucleus orientation difference of the aluminum alloy obtained after co-processing is 0.5~2.0°, the standard value of the average nucleus orientation difference is 0.1~0.4°, the value range of the average nucleus orientation difference is 0.5~2.5°, and the ratio of the average nucleus orientation difference to the maximum orientation difference is 5~30%.

[0030] Compared with related technologies, the aluminum alloy preparation method of this embodiment firstly designs the reduction rate of the first cold rolling to be greater than or equal to 60%, which introduces higher deformation energy into the aluminum material. This improves the nucleation rate during the subsequent recrystallization annealing process, resulting in a finer and more uniform grain structure, thus laying a key microstructural foundation for achieving a uniform microstructure distribution in the aluminum alloy. Secondly, by distributing the total reduction rate of the second cold rolling across multiple cold rolling passes, a high dislocation density can be accumulated to fully obtain the dislocation strengthening effect while effectively avoiding the problems of dislocation entanglement and uneven microstructure distribution caused by excessive deformation in a single pass. Finally, combined with recovery annealing at a temperature of 70~120℃, dislocation rearrangement and annihilation can be further promoted to improve the uniformity of microstructure distribution. The aluminum alloy prepared by the method of this invention has a yield strength greater than or equal to 360MPa and can withstand a bending angle of 90° and an inner bending radius of 0.5mm without cracking, thus simultaneously achieving high strength and high bending performance of the aluminum alloy.

[0031] Example 2 This embodiment provides an aluminum alloy, which is made by the aluminum alloy preparation method in Embodiment 1 above. Since the aluminum alloy in this embodiment is made by the aluminum alloy preparation method in Embodiment 1 above, the aluminum alloy in this embodiment can also achieve the technical effects achieved by the aluminum alloy preparation method in Embodiment 1 above, and will not be described in detail here.

[0032] The above description is merely an embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural or procedural transformations made based on the content of the present invention specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. A method for preparing an aluminum alloy, characterized in that, The preparation method of the aluminum alloy includes the following steps in sequence: casting, milling, homogenization treatment, hot rolling, first cold rolling, recrystallization annealing, and co-treatment; the reduction rate of the first cold rolling is greater than or equal to 60%; the co-treatment includes a second cold rolling and recovery annealing; the reduction rate of the second cold rolling is 10-30%, and the second cold rolling includes multiple cold rolling passes, with a reduction rate of 2-5% for each cold rolling pass; the number of recovery annealing passes is one less than the number of cold rolling passes, and recovery annealing is performed after each cold rolling pass except for the last cold rolling pass, with the recovery annealing temperature being 70-120℃ and the recovery annealing time being 1-4 hours.

2. The method for preparing the aluminum alloy as described in claim 1, characterized in that, The second cold rolling includes 2 to 6 cold rolling passes; the recovery annealing includes 1 to 5 passes.

3. The method for preparing the aluminum alloy as described in claim 1, characterized in that, The final rolling temperature for hot rolling is 300~350℃.

4. The method for preparing the aluminum alloy as described in claim 1, characterized in that, The recrystallization annealing temperature is 250~450℃, and the recrystallization annealing time is 10~20h.

5. The method for preparing the aluminum alloy as described in claim 1, characterized in that, The grain size of the aluminum material after recrystallization annealing is 5~20μm.

6. The method for preparing the aluminum alloy as described in claim 1, characterized in that, The yield strength of aluminum decreased by 2-20 MPa after each re-annealing.

7. The method for preparing the aluminum alloy as described in claim 1, characterized in that, The average dislocation density of the aluminum alloy obtained after co-processing is 2×10⁻⁶. 14 ~20×10 14 m -2 .

8. The method for preparing the aluminum alloy as described in claim 1, characterized in that, The average nucleus orientation difference of the aluminum alloy obtained after co-processing is 0.5~2.0°, the standard value of the average nucleus orientation difference is 0.1~0.4°, the value range of the average nucleus orientation difference is 0.5~2.5°, and the ratio of the average nucleus orientation difference to the maximum orientation difference is 5~30%.

9. An aluminum alloy, characterized in that, The aluminum alloy is made by the method for preparing the aluminum alloy according to any one of claims 1 to 8.

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