Preparation method of optical aluminum alloy material

Abstract

The invention belongs to the technical field of aluminum alloy material preparation, and particularly relates to a preparation method of an optical aluminum alloy material, which comprises the following steps: heating an aluminum alloy cast ingot to 230-270 DEG C, preserving heat, carrying out hot rolling, cooling to room temperature, carrying out cold rolling, and sequentially carrying out intermediate annealing, solution treatment and aging treatment to obtain the optical aluminum alloy material. According to the method, grains are obviously refined, the surface roughness is reduced, and the surface quality of the optical aluminum alloy material is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of aluminum alloy material preparation, and specifically relates to a method for preparing an optical aluminum alloy material. Background Art

[0002] Aluminum alloy has become a new generation of metal-based optical reflector material to replace traditional optical glass due to its advantages such as wide spectrum, high reflectivity, no athermalization and good processability. Europe and the United States have widely used it in military high-end optical detection and guidance systems. At the same time, it is also continuing to grow rapidly in emerging civilian fields such as automotive radar, semiconductor devices and high-end consumer electronics.

[0003] Existing research has found that the key to improving the quality of optical aluminum alloy reflective imaging is to achieve a low-roughness smooth surface after precision cutting by controlling its grain refinement. At present, there are two main technical paths for preparing optical aluminum alloy fine-grained materials at home and abroad. One is to use rapid solidification technology such as melt spinning / spinning to obtain thin sheets with fine grains, and then compact them into large billets; the other is to subject the homogenized aluminum alloy ingot to large plastic deformation to obtain deformed fine-grained structure.

[0004] The thin strip produced by the above-mentioned rapid solidification technology actually only has fine-grained structure on the surface layer in contact with the cooling wheel. In the thickness direction away from the wheel, it is still dominated by 10μm columnar crystals and dendrites. It usually needs to be cut into smaller particles and compacted into billets through cold isostatic pressing, hot isostatic pressing, forging and other methods to further refine the grains. Therefore, its overall time and economic cost are high and cannot meet the application end's demand for mass-production and low-cost manufacturing of related products. The technical route of using homogenized ingot large plastic deformation also faces the problem of high process energy consumption and long cycle. Summary of the invention

[0005] The technical problem to be solved by the present invention is to provide a method for preparing an optical aluminum alloy material, which can significantly refine the grains, reduce the surface roughness, and improve the surface quality of the optical aluminum alloy material.

[0006] An embodiment of the present invention provides a method for preparing an optical aluminum alloy material, wherein an aluminum alloy ingot is heated to 230-270° C., hot rolled after heat preservation, then cold rolled after cooling to room temperature, and then intermediate annealing, solution treatment, and aging treatment are sequentially performed to obtain the optical aluminum alloy material.

[0007] Preferably, the aluminum alloy ingot is heated to 240-260° C. and kept warm for 1.5-2.5 hours.

[0008] Preferably, the total reduction of the hot rolling is 60-80%.

[0009] Preferably, the total reduction of the cold rolling is 60-80%.

[0010] Preferably, the intermediate annealing temperature is 400-420° C., the annealing time is 20-50 min, and the annealing is performed in air cooling to room temperature.

[0011] Preferably, the solution treatment temperature is 510-535° C., the solution treatment time is 20-50 min, and the solution is cooled to room temperature by water.

[0012] Preferably, the aging treatment temperature is 160-190° C., and the aging treatment time is 8-12 h.

[0013] Preferably, the aluminum alloy ingot is obtained by semi-continuous casting.

[0014] Preferably, the aluminum alloy is an aluminum-magnesium-silicon-aluminum alloy.

[0015] Preferably, the aluminum alloy is 6061 aluminum alloy.

[0016] The beneficial effect of the present invention is that the present invention provides a low-cost and efficient preparation method for optical aluminum alloy materials, and achieves the purpose of uniform grain refinement and low-cost and efficient preparation by adopting the method of low-temperature pressing and forming of cast aluminum alloy materials. Studies have shown that the obtained cast aluminum alloy has higher energy dissipation efficiency and smaller rheological instability zone, and better hot working performance. At the same time, the large number of second phases in the cast aluminum alloy can promote the particle excitation nucleation mechanism, and a fine equiaxed grain structure can be obtained after pressing and forming.

[0017] The present invention innovatively utilizes the microstructural feature of grain boundary element segregation in the cast aluminum alloy structure. During the deformation process, it hinders the movement of dislocations and causes them to entangle in large quantities, transforming them into multi-oriented subgrain structures, and then forms the fine grain structure required for optical aluminum alloys through the recrystallization mechanism. At the same time, it utilizes the characteristics of the presence of a large number of second phase particles in the cast material to promote recrystallization nucleation during the deformation process and further refine the grain structure.

[0018] Compared with the rapid solidification fine crystal technology, this technology directly uses ingots for rolling, without the need to collect thin strips of several millimeters and compact the materials through hot isostatic pressing, extrusion, etc., and the material output rate is significantly improved.

[0019] The present invention does not need to perform homogenization heat treatment on the ingot. It is further found that if homogenization heat treatment is performed, the size of the grains will be increased and the roughness will be improved. The present invention adopts medium-temperature rolling for deformation in the hot rolling stage. The temperature of the medium-temperature rolling cannot exceed 270°C, and is preferably 230-270°C. On the one hand, it greatly reduces the energy loss and the risk of material overburning caused by high-temperature and long-term heating during material preparation. In addition, the medium-temperature rolling can reduce the grain size and reduce the roughness. The present invention adopts cold rolling to finish the deformation, which can improve the surface quality while enhancing the degree of material refinement. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is a process flow chart of Example 1 of the present invention.

[0021] Figure 2 This is the EBSD structure test result of the optical aluminum alloy material of Example 1 of the present invention.

[0022] Figure 3 This is the grain orientation distribution diagram of the optical aluminum alloy material of Example 1 of the present invention.

[0023] Figure 4 This is the EBSD structure test result of the optical aluminum alloy material of comparative example 1 of the present invention.

[0024] Figure 5 This is the grain orientation distribution diagram of the optical aluminum alloy material of Comparative Example 1 of the present invention.

[0025] Figure 6 This is the EBSD structure test result of the optical aluminum alloy material of Comparative Example 2 of the present invention.

[0026] Figure 7 This is the grain orientation distribution diagram of the optical aluminum alloy material of Comparative Example 2 of the present invention. DETAILED DESCRIPTION

[0027] Example 1 like Figure 1 As shown, a method for preparing an optical aluminum alloy material comprises the following steps: 1. A 6061 aluminum alloy ingot was prepared by a semi-continuous casting method, retaining the initial cast structure. The diameter of the ingot was 178 mm and the length was 630 mm.

[0028] 2. The ingot obtained in step 1 is sequentially subjected to medium temperature preheating, medium temperature rolling, and cold rolling to obtain a deformed aluminum alloy cold-rolled sheet.

[0029] The specific steps are: heating the ingot to 250°C along with the heat treatment furnace, and keeping the heat treatment furnace warm for 2 hours after reaching the set temperature; hanging the preheated ingot on the finishing mill and rolling it to 100mm at a reduction of 70% to obtain a medium-temperature rolled plate; after the medium-temperature rolled plate is air-cooled to room temperature, it is further rolled to 30mm at a reduction of 70% at room temperature to obtain a cold-rolled plate.

[0030] 3. The cold-rolled sheet obtained in step 2 is annealed to obtain an annealed aluminum alloy rolled sheet.

[0031] The specific steps are: annealing the cold-rolled sheet at 410° C. for 0.5 h to obtain an annealed rolled sheet.

[0032] 4. The annealed rolled sheet obtained in step 3 is subjected to solution treatment and artificial aging treatment in sequence to obtain a T6 state optical aluminum alloy.

[0033] The specific steps are: solutionizing the annealed rolled plate at 525°C for 3 hours, quenching with water to room temperature, and then aging at 177°C for 10 hours to obtain an optical aluminum alloy material.

[0034] The microstructure test results of the optical aluminum alloy material obtained in Example 1 are as follows: Figure 2-3 As shown, a fine recrystallized grain structure was obtained with an average grain size of 6.7 μm.

[0035] Comparative Example 1 Compared with Example 1, the difference between Comparative Example 1 and Example 1 is: After step 1 is completed, a homogenization annealing treatment is first performed, that is, the temperature is kept at 560° C. for 7 hours, and then other steps are performed. The other steps are the same as those in Example 1.

[0036] The microstructure test results of the optical aluminum alloy material obtained in Comparative Example 1 are as follows: Figure 4-5 As shown, a fine recrystallized grain structure is obtained with an average grain size of 38.4 μm, indicating that after the homogenization ingot is cast, the element segregation at the grain boundary is eliminated, which cannot promote the formation of subgrains and recrystallization transformation during subsequent deformation, resulting in coarsening of the grains.

[0037] Comparative Example 2 Compared with Example 1, Comparative Example 2 has the following differences: The medium temperature preheating in step 2 is replaced by high temperature rolling, and the temperature of high temperature rolling is 350°C, that is, step 2 is: The ingot is heated to 350℃ along with the heat treatment furnace, and the heat treatment furnace is kept warm for 2 hours after reaching the set temperature. The preheated ingot is hoisted on the finishing mill and rolled to 100mm at a reduction of 70% to obtain a high-temperature rolled plate; after the high-temperature rolled plate is air-cooled to room temperature, it is further rolled to 30mm at a reduction of 70% at room temperature to obtain a cold-rolled plate.

[0038] The other steps are the same as those in Example 1.

[0039] The microstructure test results of the optical aluminum alloy material obtained in Comparative Example 2 are as follows: Figure 6-7 As shown, a fine recrystallized grain structure is obtained with an average grain size of 36.2 μm, indicating that after high-temperature rolling, segregation in the structure is eliminated, the second phase is reduced, and dynamic recovery is enhanced, so the recrystallization nucleation is significantly reduced. At the same time, dynamic recrystallization is suppressed, resulting in grain coarsening.

[0040] After single-point diamond cutting was performed on the materials obtained in Example 1, Comparative Example 1 and Comparative Example 2, surface roughness was tested by white light interferometry. The test results are shown in Table 1.

[0041] Table 1 Surface roughness test results

[0042] It can be seen from Table 1 that the technical solution proposed in the present invention significantly refines the grains, allowing it to have a high-precision machined surface.

[0043] A person skilled in the art should understand that the discussion of any of the above embodiments is merely illustrative and is not intended to imply that the scope of protection of the present application is limited to these examples. In line with the concept of the present application, the technical features in the above embodiments or different embodiments may be combined, the steps may be implemented in any order, and there are many other variations of different aspects of one or more embodiments of the present application as described above, which are not provided in detail for the sake of simplicity.

[0044] One or more embodiments of the present application are intended to cover all such substitutions, modifications and variations that fall within the broad scope of the present application. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of one or more embodiments of the present application should be included in the protection scope of the present application.

Claims

1. A method for preparing an optical aluminum alloy material, characterized in that: The aluminum alloy ingot is heated to 230-270°C, hot-rolled after being kept warm, then cold-rolled after being cooled to room temperature, and then intermediate annealing, solution treatment, and aging treatment are performed in sequence to obtain an optical aluminum alloy material.

2. The preparation method according to claim 1, characterized in that: The aluminum alloy ingot is heated to 240-260° C. and kept warm for 1.5-2.5 hours.

3. The preparation method according to claim 1, characterized in that: The total reduction of the hot rolling is 60-80%.

4. The preparation method according to claim 1, characterized in that: The total reduction of the cold rolling is 60-80%.

5. The preparation method according to any one of claims 1 to 4, characterized in that: The intermediate annealing temperature is 400-420° C., the annealing time is 20-50 min, and the annealing is performed by air cooling to room temperature.

6. The preparation method according to any one of claims 1 to 4, characterized in that: The solution treatment temperature is 510-535° C., the solution treatment time is 20-50 min, and the solution treatment is cooled to room temperature by water.

7. The preparation method according to any one of claims 1 to 4, characterized in that: The temperature of the aging treatment is 160-190° C., and the time of the aging treatment is 8-12 hours.

8. The preparation method according to any one of claims 1 to 4, characterized in that: The aluminum alloy ingot is obtained by semi-continuous melting and casting.

9. The preparation method according to any one of claims 1 to 4, characterized in that: The aluminum alloy is an aluminum-magnesium-silicon-aluminum alloy.

10. The preparation method according to claim 9, characterized in that: The aluminum alloy is 6061 aluminum alloy.

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