Aluminum alloy, preparation method and application thereof

Abstract

The present application provides an aluminum alloy, a preparation method thereof and an application thereof. The preparation method of the aluminum alloy comprises the following steps: aluminum liquid smelting, casting, homogenization, extrusion and pipe drawing and heat treatment. By adding beryllium element to pure aluminum, the melt absorption tendency is reduced during the aluminum liquid smelting process, and the air entrainment, inclusion and burning of the aluminum alloy are greatly reduced. Then, by heat treatment at 220℃-280℃, a large amount of spheroidized β (Mg2Al3) phase can be formed in the aluminum alloy crystal, and dispersedly distributed on the α (Al) phase, so as to improve the hardness of the aluminum alloy itself. After the aluminum alloy is prepared into a lens mount for a single-lens reflex camera, the tolerance grade of the mount can be controlled below IT0, the roughness of the mount surface can be reduced, the amount of chip entanglement of the tool head during the CNC process of the mount can be reduced, the difficulty of CNC processing can be reduced, the processing quality and dimensional stability of the mount can be improved, the quality of the mount can be improved, and the shaking of the mount during the assembly process can be avoided, so as to significantly improve the user experience.

Description

Technical Field

[0001] The present application belongs to the technical field of precision metal parts processing, and specifically relates to an aluminum alloy, a preparation method thereof, and an application thereof. Background Art

[0002] In the prior art, such as Figure 1 As shown, the lens mount of a SLR camera refers to the interface between the camera body and the lens. The camera's autofocus is achieved through the metal contacts on the mount. The current mainstream lens mounts include Canon EF mount, Pentax K mount and Sony E mount. The mount is an important connector, and its assembly stability and oxidation quality place high demands on the surface quality and dimensional stability of machined products. Different camera brands and models usually use different lens mounts, which are incompatible with each other in physical and electrical specifications. Therefore, it is usually impossible to install an A-mount lens on a B-mount body without losing automation functions.

[0003] In the prior art, as the audience of SLR cameras becomes more and more professional, equipment processing manufacturers have increasingly stringent requirements for raw materials. They are not satisfied with good oxidation surface quality and glossiness, but also need to ensure that the raw materials have excellent processing performance during turning, without chip entanglement, and can effectively extend the service life of machining tools. The existing SLR camera lens mount material is mainly 5056H32 aluminum alloy or 5083H111 aluminum alloy, which is composed of 4.5%-5.6% Mg, 0.05%-0.2% Cr, the remainder of aluminum and inevitable impurities by mass fraction. It is a heat-treatment non-strengthening alloy with a high heat treatment threshold. If the stabilization heat treatment is not appropriate after the tube is extracted, the hardness of the aluminum alloy will drop significantly, deteriorating the machining surface quality and dimensional stability of the material, reducing the machining surface quality and dimensional stability, and the user will experience shaking during the assembly of the mount, which significantly reduces the user experience. Therefore, improvements are urgently needed. Summary of the invention

[0004] In order to solve the technical problem that in the prior art, the material of the bayonet mount of a SLR camera head is usually 5056H32 aluminum alloy or 5083H111 aluminum alloy, both of which are heat-treatment non-strengthening alloys, and the heat treatment process threshold is relatively high. If the heat treatment is improper, the hardness of the two aluminum alloys will be significantly reduced, which will significantly increase the difficulty of turning the alloy material, increase the amount of swarf entanglement during machining, and deteriorate the machining surface quality and dimensional stability of the alloy material, reduce the machining surface quality and dimensional stability, and cause shaking during the assembly of the bayonet, which significantly reduces the user's experience, the application provides an aluminum alloy;

[0005] In order to solve the technical problems that the aluminum alloy commonly used in the prior art has high difficulty in heat treatment, low hardness, high chip entanglement of the cutter head during CNC processing, easy deterioration of the processing quality and dimensional stability of the workpiece surface during CNC processing, the tolerance of the workpiece will be significantly improved, the quality stability is low after being prepared into a SLR camera mount, and the user will shake during the assembly of the mount, which significantly reduces the user's experience, a method for preparing an aluminum alloy is provided;

[0006] In order to solve the technical problem raised by the present application, the present application also provides an application of aluminum alloy, which is specifically used for CNC processing into a lens mount for a SLR camera.

[0007] The present application adopts the following scheme, a method for preparing an aluminum alloy, comprising the following steps:

[0008] Aluminum liquid smelting: add aluminum ingots, aluminum-containing recycled materials, magnesium ingots with a purity greater than 99.95%, 75 chromium additives, fast-melting silicon, iron additives, copper additives, manganese additives, zinc ingots, titanium additives and aluminum-beryllium alloy into the smelting furnace in sequence, stir them fully at 740℃-760℃ and 1200rpm-1300rpm, take samples regularly for spectral analysis, control the composition of the aluminum liquid melt within the target range, and obtain crude aluminum liquid;

[0009] Among them, the aluminum ingot is an aluminum ingot with a purity greater than 99.9%, the aluminum content in the aluminum recycled material is 50%-55%, the brand of 75 chromium additive is ZS-Cr75, the brand of fast-melting silicon is ZS-Si95, the brand of iron additive is ZS-Fe75, the brand of manganese additive is ZS-Mn80, the purity of zinc ingot is greater than 90%, the remainder is solvent, the brand of titanium additive is ZS-Ti75, and the beryllium content in aluminum-beryllium alloy is 3%-5%.

[0010] Casting: the crude aluminum liquid is transferred to a refining furnace, and after refining, the scum on the surface of the crude aluminum liquid is scraped off to obtain refined aluminum liquid, and the refined aluminum liquid is transferred to a casting mold and cooled to obtain a crude aluminum alloy;

[0011] Homogenization treatment: the prepared crude aluminum alloy is transferred to a homogenization furnace, and homogenized at 495°C-510°C for 8-12 hours. After the homogenization, the temperature is lowered to room temperature at a cooling rate of 20°C / min-30°C / min to obtain a homogenized aluminum alloy.

[0012] Based on the first aspect, the aluminum alloy provided by the present invention is doped with Be. Compared with the traditional 5083 aluminum alloy and 5056 aluminum alloy, during the smelting process of the aluminum liquid, the aluminum alloy provided by the present application has an oxide film on the surface of the melt converted from α-alumina to γ-alumina, and the air absorption tendency of the melt is significantly reduced, which can greatly reduce the air entrainment and inclusions of the finished aluminum alloy product. At the same time, the burning loss of magnesium in the aluminum alloy during the casting process can also be reduced, which significantly improves the yield rate. Homogenizing the coarse particles in the homogenizing furnace is conducive to fully homogenizing the elements in the aluminum alloy melt, thereby preventing the generation of element segregation, and further facilitating the refinement of the alloy and reducing the size of the aluminum alloy grains.

[0013] Extrusion tube drawing: After heating the prepared homogenized aluminum alloy to 500°C-530°C, transfer it to a press, keep it at a barrel temperature of 390°C-430°C for 30min-60min, and extrude it at an extrusion speed of 3.5m-5m / min to obtain an aluminum alloy semi-finished product;

[0014] Heat treatment: The prepared aluminum alloy semi-finished product is transferred to a stabilization furnace, heat treated at 220°C-280°C for 12hr-18hr, and then cooled to room temperature to obtain an aluminum alloy finished product.

[0015] In a possible implementation manner, the heat treatment includes a first temperature rise stage, a first temperature keeping stage, a second temperature rise stage, a second temperature keeping stage, a first temperature drop stage and a second temperature drop stage, which are performed in chronological order;

[0016] The first cooling stage is to heat the aluminum alloy semi-finished product from room temperature to 220° C.

[0017] The first heat preservation stage is to keep the aluminum alloy semi-finished product at 220°C;

[0018] The second heating stage is to heat the aluminum alloy semi-finished product from 220° C. to 280° C.;

[0019] The second heat preservation stage is to keep the aluminum alloy semi-finished product at 280° C.

[0020] The first cooling stage is to cool the aluminum alloy semi-finished product from 280° C. to 150° C. in the stabilization furnace;

[0021] The second cooling stage is to cool the aluminum alloy semi-finished product from 150° C. to room temperature outside the stabilization furnace.

[0022] In one possible implementation,

[0023] The heating rate of the first heating stage is 3°C / min-4.25°C / min;

[0024] The insulation time of the first insulation stage is 6hr-8hr;

[0025] The heating rate of the second heating stage is 1°C / min-2.25°C / min;

[0026] The second heat preservation stage has a heat preservation time of 6 hr to 8 hr;

[0027] The cooling rate in the first cooling stage is 0.5°C / min-1.25°C / min.

[0028] Based on the first aspect, by first keeping the temperature at 220℃ for 6 hours, the β (Mg2Al3) phase can be promoted to precipitate and spheroidize in the crystal first, and then keeping the temperature at 280℃ for 6 hours to accelerate the transformation of β' (Mg2Al3) to β (Mg2Al3) phase, precipitate a large amount at the grain boundary and in the crystal, and disperse on α (Al), which is beneficial to improve the dimensional stability and corrosion resistance of the bayonet material. The β (Mg2Al3) metallographic phase is spheroidized by heat treatment. During the CNC process, the surface roughness of the bayonet can be effectively reduced, and the spheroidized β (Mg2Al3) metallographic phase can effectively improve the wear resistance of the bayonet, and it is not easy to produce pits and scratches during the processing process, which can significantly reduce the tolerance level of the bayonet, further improve the assembly stability of the bayonet, avoid shaking during the bayonet assembly process, and significantly improve the yield rate in the production process;

[0029] In a possible implementation, during the smelting of the aluminum liquid, an oxide film is formed on the surface of the aluminum liquid melt, and the material of the oxide film is γ-alumina.

[0030] In a possible embodiment, during the heat treatment, in the first heat preservation stage, the β (Mg2Al3) phase in the aluminum alloy semi-finished product crystals precipitates and spheroidizes, and in the second heat preservation stage, the β (Mg2Al3) phase in the aluminum alloy semi-finished product crystals precipitates and spheroidizes. ’ The (Mg2Al3) phase transforms to the β(Mg2Al3) phase, and β(Mg2Al3) precipitates in large quantities and is dispersed on the α(Al) phase.

[0031] In order to solve the technical problem raised by the present application, the present application provides an aluminum alloy, which is prepared by the above-mentioned method for preparing an aluminum alloy, and the aluminum alloy is composed of the following components in mass percentage: Si 0.01%-0.1%, Fe 0.05%-0.1%, Cu 0.003%-0.01%, Mn 0.2%-0.4%, Mg 5.5%-6.5%, Cr 0.15%-0.35%, Zn 0.005%-0.01%, Ti 0.01%-0.02%, Be 0.005%-0.008%, and the rest are Al and other inevitable impurity elements, and the total amount of other inevitable impurity elements is ≤0.005%.

[0032] In a possible embodiment, in the crystal, the dendrite grid is completely dissolved and the average grain size is 28 μm-31 μm.

[0033] In a possible implementation manner, the average Rockwell hardness is 43HRB-55HRB.

[0034] In a possible implementation manner, the average surface roughness is Ra0.1-Ra0.2.

[0035] In order to solve the technical problem raised by the present application, the present application provides an application of an aluminum alloy, which is prepared by the above-mentioned method for preparing an aluminum alloy, and the aluminum alloy is used as the material of a single-lens reflex camera lens mount, and the single-lens reflex camera lens mount is obtained by CNC processing, and the tolerance grade of the single-lens reflex camera lens mount is less than or equal to IT0.

[0036] Compared with the prior art, this application has the following beneficial effects:

[0037] The present application provides an aluminum alloy, a preparation method thereof and an application thereof. The preparation method of the aluminum alloy comprises the following steps: aluminum liquid smelting, casting, homogenization, extrusion and pipe drawing and heat treatment. By adding beryllium element to pure aluminum, the melt gas absorption tendency is reduced during the aluminum liquid smelting process, and the phenomenon of air entrainment, inclusion and burning of the aluminum alloy is greatly reduced. Then, by heat treatment under the condition of 220℃-280℃, a large amount of spheroidized β (Mg2Al3) phase can be formed in the aluminum alloy crystal, and dispersedly distributed on the α (Al) phase, so as to improve the hardness of the aluminum alloy itself. After the aluminum alloy is prepared into a lens mount for a single-lens reflex camera, the tolerance grade of the mount can be controlled below IT0, the roughness of the mount surface can be reduced, the amount of chip entanglement of the tool head of the mount during the CNC process can be reduced, the difficulty of CNC processing can be reduced, the processing quality and dimensional stability of the mount can be improved, the quality of the mount can be improved, and the shaking of the mount during the assembly process can be avoided, which significantly improves the user experience. The invention has the advantages of convenient processing, reduced overall processing difficulty, improved mount assembly experience and stability, and easy promotion and implementation. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 It is a structural schematic diagram of a SLR camera lens mount in the prior art;

[0039] Figure 2 It is a heat treatment curve diagram during the heat treatment process in a method for preparing an aluminum alloy of the present application;

[0040] Figure 3 is a scanning electron microscope image of the metallographic structure of the aluminum alloy purchased in Comparative Example 1 of the present application;

[0041] Figure 4is a scanning electron microscope image of the metallographic structure of the aluminum alloy prepared in Example 3 of the present application;

[0042] Figure 5 It is a scanning electron microscope image of the metallographic structure of the aluminum alloy purchased in Comparative Example 2 of the present application. DETAILED DESCRIPTION

[0043] Combination Figure 1-Figure 5 , Examples 1-3 and Comparative Examples 1-2, further illustrate the technical solution.

[0044] Example 1

[0045] (1) Preparation method of aluminum alloy:

[0046] Step 101. Aluminum liquid smelting: according to the target alloy composition table shown in Table 1, aluminum ingots, aluminum-containing recycled materials, magnesium ingots with a purity greater than 99.95%, 75 chromium additives, fast-melting silicon, iron additives, copper additives, manganese additives, zinc ingots, titanium additives and aluminum-beryllium alloy are sequentially added into the smelting furnace, and fully stirred at 745° C. and 1220 rpm. Samples are taken regularly for spectral analysis to ensure that the composition of the aluminum liquid is within the target range, thereby obtaining crude aluminum liquid;

[0047] Step 102. Casting: the crude aluminum liquid is transferred to a refining furnace, and after refining, the scum on the surface of the crude aluminum liquid is scraped off to obtain refined aluminum liquid, and the refined aluminum liquid is transferred to a casting mold for cooling and forming to obtain a crude aluminum alloy, which is a bar with a specification of φ229*6000mm;

[0048] Step 103. Homogenization treatment: the prepared crude aluminum alloy is transferred to a homogenization furnace, and homogenized at 495° C. for 9 hours. After the homogenization, the temperature is lowered to room temperature at a cooling rate of 20° C. / min to obtain a homogenized aluminum alloy.

[0049] Step 104. Extrusion tube drawing: After heating the prepared homogenized aluminum alloy to 510° C., transfer it to a press, keep it at a barrel temperature of 400° C. for 40 minutes, and extrude it at an extrusion speed of 3.5 m to obtain an aluminum alloy semi-finished product;

[0050] Step 105. Heat treatment: refer to Figure 2Heat treatment curve of aluminum alloy semi-finished products: the prepared aluminum alloy semi-finished products are transferred to a stabilization furnace, heated from room temperature to 220°C at a heating rate of 3°C / min and kept warm for 6 hours, then heated from 220°C to 280°C at a heating rate of 1°C / min and kept warm for 6 hours, then cooled from 280°C to 150°C in the stabilization furnace at a cooling rate of 0.5°C / min, and finally transferred out of the stabilization furnace, cooled from 150°C to room temperature to obtain aluminum alloy products, which are bars.

[0051] (2) Preparation of SLR camera lens mount

[0052] After the corresponding drawing of the SLR camera lens mount is imported into the CNC processing equipment, the finished aluminum alloy product prepared in (1) of Example 1 is transferred to the CNC processing equipment to obtain the finished SLR camera lens mount product.

[0053] Example 2

[0054] (1) Preparation method of aluminum alloy:

[0055] Step 101. Aluminum liquid smelting: according to the target alloy composition table shown in Table 1, aluminum ingots, aluminum-containing recycled materials, magnesium ingots with a purity greater than 99.95%, 75 chromium additives, fast-melting silicon, iron additives, copper additives, manganese additives, zinc ingots, titanium additives and aluminum-beryllium alloy are sequentially added into the smelting furnace, and the mixture is fully stirred at 750° C. and 1250 rpm. Samples are taken regularly for spectral analysis to ensure that the composition of the aluminum liquid is within the target range, thereby obtaining crude aluminum liquid;

[0056] Step 102. Casting: the crude aluminum liquid is transferred to a refining furnace, and after refining, the scum on the surface of the crude aluminum liquid is scraped off to obtain refined aluminum liquid, and the refined aluminum liquid is transferred to a casting mold for cooling and forming to obtain a crude aluminum alloy, which is a bar with a specification of φ229*6000mm;

[0057] Step 103. Homogenization treatment: the prepared crude aluminum alloy is transferred to a homogenization furnace, and homogenized at 500° C. for 10 hours. After the homogenization, the temperature is lowered to room temperature at a cooling rate of 25° C. / min to obtain a homogenized aluminum alloy.

[0058] Step 104. Extrusion tube drawing: After heating the prepared homogenized aluminum alloy to 520° C., transfer it to a press, keep it at a barrel temperature of 420° C. for 50 minutes, and extrude it at an extrusion speed of 4 m / min to obtain an aluminum alloy semi-finished product;

[0059] Step 105. Heat treatment: refer to Figure 2Heat treatment curve of aluminum alloy semi-finished products: the prepared aluminum alloy semi-finished products are transferred to a stabilization furnace, heated from room temperature to 220℃ and kept warm for 7 hours at a heating rate of 3.6℃ / min, then heated from 220℃ to 280℃ and kept warm for 7 hours at a heating rate of 1.5℃ / min, then cooled from 280℃ to 150℃ in a stabilization furnace at a cooling rate of 1℃ / min, and finally the aluminum alloy semi-finished products are transferred outside the stabilization furnace and cooled from 150℃ to room temperature to obtain aluminum alloy products, which are bars.

[0060] (2) Preparation of SLR camera lens mount

[0061] After the corresponding drawing of the SLR camera lens mount is imported into the CNC processing equipment, the finished aluminum alloy product prepared in (1) of Example 2 is transferred to the CNC processing equipment to obtain the finished SLR camera lens mount product.

[0062] Example 3

[0063] (1) Preparation method of aluminum alloy:

[0064] Step 101. Aluminum liquid smelting: according to the target alloy composition table shown in Table 1, aluminum ingots, aluminum-containing recycled materials, magnesium ingots with a purity greater than 99.95%, 75 chromium additives, fast-melting silicon, iron additives, copper additives, manganese additives, zinc ingots, titanium additives and aluminum-beryllium alloy are sequentially added into the smelting furnace, and fully stirred at 760° C. and 1300 rpm. Samples are taken regularly for spectral analysis to ensure that the composition of the aluminum liquid is within the target range, thereby obtaining crude aluminum liquid;

[0065] Step 102. Casting: the crude aluminum liquid is transferred to a refining furnace, and after refining, the scum on the surface of the crude aluminum liquid is scraped off to obtain refined aluminum liquid, and the refined aluminum liquid is transferred to a casting mold for cooling and forming to obtain a crude aluminum alloy, which is a bar with a specification of φ229*6000mm;

[0066] Step 103. Homogenization treatment: the prepared crude aluminum alloy is transferred to a homogenization furnace, and kept at 505° C. for 12 hours. After the homogenization, the temperature is lowered to room temperature at a cooling rate of 30° C. / min to obtain a homogenized aluminum alloy.

[0067] Step 104. Extrusion tube drawing: After heating the prepared homogenized aluminum alloy to 530° C., transfer it to a press, keep it warm for 60 minutes under the condition of a barrel temperature of 390° C.-430° C., and extrude it at an extrusion speed of 5 m / min to obtain an aluminum alloy semi-finished product;

[0068] Step 105. Heat treatment: refer to Figure 2Heat treatment curve of aluminum alloy semi-finished products: the prepared aluminum alloy semi-finished products are transferred to a stabilization furnace, heated from room temperature to 220°C and kept warm for 8 hours at a heating rate of 4.25°C / min, then heated from 220°C to 280°C and kept warm for 8 hours at a heating rate of 2.25°C / min, then cooled from 280°C to 150°C in a stabilization furnace at a cooling rate of 1.25°C / min, finally transferred out of the stabilization furnace, cooled from 150°C to room temperature to obtain aluminum alloy products, which are bars.

[0069] (2) Preparation of SLR camera lens mount

[0070] After the corresponding drawing of the SLR camera lens mount is imported into the CNC processing equipment, the finished aluminum alloy product prepared in (1) of Example 1 is transferred to the CNC processing equipment to obtain the finished SLR camera lens mount product.

[0071] Comparative Example 1

[0072] Commercially available 5083H111 aluminum alloy and a SLR camera mount manufactured from the 5083H111 aluminum alloy by CNC process;

[0073] During the production process, the heat treatment process is: heating from room temperature to 270℃ and then keeping warm for 10 hours.

[0074] Comparative Example 2

[0075] Commercially available 5056H32 aluminum alloy and SLR camera mount made from 5083H111 aluminum alloy by CNC process;

[0076] During the production process, the heat treatment process is: heating from room temperature to 270℃ and then keeping warm for 5 hours.

[0077] Table 1 Aluminum alloy composition in Examples 1-3 and Comparative Examples 1-2

[0078]

[0079] Note: The influence of inevitable impurities is ignored in Table 1. The Al content includes inevitable impurities, and the content of inevitable impurities meets the standards and can be ignored.

[0080] The aluminum alloys prepared in Examples 1-3 and the aluminum alloys purchased in Comparative Examples 1-2 were tested as follows:

[0081] Test 1: Surface roughness test: The SLR camera lens mounts prepared in Examples 1-3 and Comparative Examples 1-2 were subjected to a friction test using a "stylus method";

[0082] Among them, the "stylus method" is to use a diamond stylus with a tip curvature radius of about 2 microns to slowly slide along the surface of the test piece to be tested. The up and down displacement of the diamond stylus is converted into an electrical signal by an electrical length sensor, and after amplification, filtering and calculation, the surface roughness value is indicated by the display instrument.

[0083] Test 2: Mount dimensional stability test, testing the outer roundness, inner roundness, tolerance grade and terminal assembly effect of the SLR camera lens mount prepared in Examples 1-3 and Comparative Examples 1-2;

[0084] Test 3: Mechanical properties, the tensile strength, Young's modulus and hardness of the aluminum alloy bar test pieces prepared in Examples 1-3 and Comparative Examples 1-2 were measured according to GB / T228.1-2021, GB / T 16865-2013, GB / T 230.1-2018, GB / T 230.2-2022 and GB / T 230.3-2022 respectively;

[0085] Among them, the roundness measurement method is to place the processed bayonet product under the projector, compare the contour image of the measured circle with the two limit concentric circles drawn on the projection screen, and thus obtain the roundness error of the measured part.

[0086] Test 4: Crystal state. The metallographic structures of the aluminum alloy products prepared in Example 3 and Comparative Examples 1-3 were observed respectively. The test results are shown in Table 2 below.

[0087] Table 2 Test results of test 1-4

[0088]

[0089] It can be seen from the alloy composition table in Table 1 and the test results in Table 2 that the aluminum alloy provided by the present invention is compared with the traditional 5083 aluminum alloy and 5056 aluminum alloy. By adjusting the alloy composition, the solid solution strengthening effect is significantly improved. After the aluminum alloy is CNC-processed into a bayonet, the strength, hardness and rigidity of the bayonet can be significantly improved, thereby better ensuring the surface quality and roundness of the bayonet machining, making it less likely to deform. Especially when the amount of turning is large at one time, the amount of chip entanglement of the CNC equipment tool head can be significantly reduced, reducing the processing difficulty;

[0090] Furthermore, the aluminum alloy provided by the present invention is doped with Be. Compared with the traditional 5083 aluminum alloy and 5056 aluminum alloy, the aluminum alloy provided by the present application has an oxide film on the surface of the melt transformed from α-alumina to γ-alumina during the molten aluminum smelting process, and the air absorption tendency of the melt is significantly reduced, which can greatly reduce the air entrainment and inclusions of the aluminum alloy product, and at the same time, the burning loss can also be reduced, which significantly improves the yield rate;

[0091] Finally, in addition to providing an aluminum alloy, the present invention also provides a heat treatment process for the aluminum alloy. In the aluminum alloy heat treatment process, the aluminum alloy is first kept at 220°C for 6 hours, which can promote the precipitation and spheroidization of the β (Mg2Al3) phase in the crystal, and then kept at 280°C for 6 hours to accelerate the transformation of β' to β (Mg2Al3) phase, precipitate a large amount at the grain boundary and in the crystal, and disperse on α (Al), which is beneficial to improving the dimensional stability and corrosion resistance of the bayonet material. The β (Mg2Al3) metallographic phase is spheroidized by heat treatment, and the surface roughness of the bayonet can be effectively reduced during the CNC process. The spheroidized β (Mg2Al3) metallographic phase can effectively improve the wear resistance of the bayonet, and it is not easy to produce pits and scratches during the processing process. The tolerance level of the bayonet can be significantly reduced, and the assembly stability of the bayonet is further improved, and shaking during the assembly process of the bayonet is avoided, and the yield rate in the production process is significantly improved.

[0092] After the traditional 5056 aluminum alloy is stabilized at 270℃ for 5 hours, the β (Mg2Al3) phase precipitates along the grain boundary, forming an integrated network. The precipitation effect is not good, the wear and corrosion resistance of the bayonet is reduced, scratches and pits are easily generated during processing, the tolerance level of the bayonet is high, and the yield rate is low;

[0093] After the traditional 5083 aluminum alloy was stabilized at 270℃ for 10 hours, in addition to the network precipitation of β (Mg2Al3) phase along the grain boundary, a large amount of polygonal AlFeMnSi impurity phase remained on α (Al), which deteriorated the precipitation effect, concentrated internal stress, and caused poor roundness of the bayonet machining. The tolerance grade was significantly improved, the yield rate was low, and the assembly effect was poor.

[0094] The present application provides an aluminum alloy, a preparation method thereof and an application thereof. The preparation method of the aluminum alloy comprises the following steps: aluminum liquid smelting, casting, homogenization, extrusion and pipe drawing and heat treatment. By adding beryllium element to pure aluminum, the melt gas absorption tendency is reduced during the aluminum liquid smelting process, and the phenomenon of air entrainment, inclusion and burning of the aluminum alloy is greatly reduced. Then, by heat treatment under the condition of 220℃-280℃, a large amount of spheroidized β (Mg2Al3) phase can be formed in the aluminum alloy crystal, and dispersedly distributed on the α (Al) phase, so as to improve the hardness of the aluminum alloy itself. After the aluminum alloy is prepared into a lens mount for a single-lens reflex camera, the tolerance grade of the mount can be controlled below IT0, the roughness of the mount surface can be reduced, the amount of chip entanglement of the tool head of the mount during the CNC process can be reduced, the difficulty of CNC processing can be reduced, the processing quality and dimensional stability of the mount can be improved, the quality of the mount can be improved, and the shaking of the mount during the assembly process can be avoided, which significantly improves the user experience. The invention has the advantages of convenient processing, reduced overall processing difficulty, improved mount assembly experience and stability, and easy promotion and implementation.

[0095] The above are only embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for preparing an aluminum alloy, characterized in that: The following steps are involved: Aluminum liquid smelting: add aluminum ingots, aluminum-containing recycled materials, magnesium ingots with a purity greater than 99.95%, 75 chromium additives, fast-melting silicon, iron additives, copper additives, manganese additives, zinc ingots, titanium additives and aluminum-beryllium alloy into the smelting furnace in sequence, stir them fully at 740℃-760℃ and 1200rpm-1300rpm, take samples regularly for spectral analysis, control the composition of the aluminum liquid melt within the target range, and obtain crude aluminum liquid; Casting: the crude aluminum liquid is transferred to a refining furnace, and after refining, the scum on the surface of the crude aluminum liquid is scraped off to obtain refined aluminum liquid, and the refined aluminum liquid is transferred to a casting mold and cooled to obtain a crude aluminum alloy; Homogenization treatment: the prepared crude aluminum alloy is transferred to a homogenization furnace, and homogenized at 495°C-510°C for 8-12 hours. After the homogenization, the temperature is lowered to room temperature at a cooling rate of 20°C / min-30°C / min to obtain a homogenized aluminum alloy. Extrusion tube drawing: After heating the prepared homogenized aluminum alloy to 500°C-530°C, transfer it to a press, keep it at a barrel temperature of 390°C-430°C for 30min-60min, and extrude it at an extrusion speed of 3.5m / min-5m / min to obtain an aluminum alloy semi-finished product; Heat treatment: the prepared aluminum alloy semi-finished product is transferred to a stabilization furnace, heat treated at 220°C-280°C for 12hr-18hr, and then cooled to room temperature to obtain an aluminum alloy finished product; The heat treatment includes a first temperature rising stage, a first temperature keeping stage, a second temperature rising stage, a second temperature keeping stage, a first temperature falling stage and a second temperature falling stage which are performed in chronological order; The first heating stage is to heat the aluminum alloy semi-finished product from room temperature to 220°C, and the corresponding heating rate is 3°C / min-4.25°C / min; The first heat preservation stage is to keep the aluminum alloy semi-finished product at 220° C. for 6 hours to 8 hours; The second heating stage is to heat the aluminum alloy semi-finished product from 220°C to 280°C, and the corresponding heating rate is 1°C / min-2.25°C / min; The second heat preservation stage is to keep the aluminum alloy semi-finished product at 280° C. for 6-8 hours; The first cooling stage is to cool the aluminum alloy semi-finished product from 280°C to 150°C in the stabilization furnace, and the corresponding cooling rate is 0.5°C / min-1.25°C / min; The second cooling stage is to cool the aluminum alloy semi-finished product from 150° C. to room temperature outside the stabilization furnace; The aluminum alloy prepared by the method for preparing an aluminum alloy is composed of the following components, by mass percentage: Si 0.01%-0.1%, Fe 0.05%-0.1%, Cu 0.003%-0.01%, Mn 0.2%-0.4%, Mg 5.5%-6.5%, Cr0.15%-0.35%, Zn 0.005%-0.01%, Ti 0.01%-0.02%, Be 0.0059%-0.008%, and the rest are Al and other inevitable impurity elements, and the total amount of other inevitable impurity elements is ≤0.005%.

2. The method for preparing an aluminum alloy according to claim 1, characterized in that: During the smelting of the aluminum liquid, an oxide film is formed on the surface of the aluminum liquid melt, and the material of the oxide film is γ-alumina.

3. The method for preparing an aluminum alloy according to claim 1, characterized in that: During the heat treatment, in the first heat preservation stage, the β (Mg2Al3) phase in the aluminum alloy semi-finished product crystals precipitates and spheroidizes, and in the second heat preservation stage, the β (Mg2Al3) phase in the aluminum alloy semi-finished product crystals precipitates and spheroidizes. ’ The (Mg2Al3) phase transforms to the β(Mg2Al3) phase, and β(Mg2Al3) precipitates in large quantities and is dispersed on the α(Al) phase.

4. The method for preparing an aluminum alloy according to claim 1, characterized in that: In the prepared aluminum alloy crystal, the dendrite grid is completely dissolved and the average grain size is 28 μm-31 μm.

5. The method for preparing an aluminum alloy according to claim 1, characterized in that: The average Rockwell hardness of the prepared aluminum alloy is 43HRB-55HRB.

6. The method for preparing an aluminum alloy according to claim 1, characterized in that: The average surface roughness of the prepared aluminum alloy is Ra0.1-Ra0.

2.

7. An application of aluminum alloy, characterized in that: The aluminum alloy is prepared by the method for preparing an aluminum alloy according to any one of claims 1 to 6, and the aluminum alloy is used as a material for a lens mount of a single-lens reflex camera.

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