High-glossiness 6xxx aluminum alloy plate capable of being anodized and preparation method thereof

Abstract

The invention discloses a high-glossiness 6xxx aluminum alloy plate capable of being anodized and a preparation method of the high-glossiness 6xxx aluminum alloy plate. An aluminum material is prepared from the following components in percentage by mass: 0.2-0.6% of Si; 0.6%-1.1% of Mg; 0.01% to 0.04% of Ti; according to the preparation method disclosed by the invention, a finished product annealing process is regulated and controlled, so that the second phase of the finished product aluminum material is uniformly distributed and small in size, and the finished product aluminum alloy plate with uniform and small grain size, average grain size of 10-30 microns, reflectivity of more than or equal to 85%, glossiness of 350-420GU, hardness of HV 25-35 and excellent surface performance is finally prepared. After the aluminum alloy plate is subjected to subsequent room-temperature stamping forming and anodic oxidation treatment, the surface color is uniform, the defects such as piebaldness are avoided, and the technical requirements of high-end products for appearance decoration surfaces can be well met.

Description

Technical Field

[0001] The invention belongs to the technical field of aluminum alloy materials, and in particular to a 6xxx series aluminum alloy plate with high gloss and suitable for anodizing treatment and a preparation method thereof. Background Art

[0002] With the sustained and rapid development of the national economy, people not only pay attention to the internal quality of products, but also put forward higher requirements for the appearance and touch of products. In the civilian consumer market, aluminum alloy materials have become one of the materials with the largest usage and the most coverage, mainly because of its many advantages such as high strength, good plasticity and toughness, smooth and bright surface, and anodizing treatment. After anodizing treatment, a layer of oxide film with both wear resistance and corrosion resistance will be formed on the surface of aluminum. After coloring treatment, the surface of aluminum presents a variety of colors, which can enhance the artistic and technological sense of the product, and become the best choice for 3C materials, shells and other surface materials.

[0003] Aluminum materials for shells are usually made of aluminum alloy ingots, which are rolled into plates and strips of a certain thickness, and then deep-drawn and CNC-processed into the desired product shape, and finally chemically polished, sandblasted and anodized to color the surface and give it a special touch. The above processing procedures require that aluminum materials for shells not only have certain strength and deep-drawing performance, but also have excellent surface properties, so that after subsequent stamping and other processing steps, chemical polishing, anodizing and other processes, there will be no surface defects such as discolored spots, processing lines and material lines on the surface of the aluminum. Based on the above processing flow and product requirements, the technical development of aluminum materials for shells should focus on further improving the surface performance and uniformity of the sheet material, so as to fundamentally improve the surface performance of the sheet material, with high gloss, and meet the technical requirements of high-end products for decorative appearance surfaces.

[0004] The aluminum material used for the shell in the prior art is prone to surface defects such as pitting, lines and even cracks during the deep drawing process, and surface defects such as spots and dull colors usually appear on the surface after anodizing, which greatly affects the surface quality of the product and causes it to be scrapped, seriously restricting the application and development of aluminum alloys in this field. Summary of the invention

[0005] The technical purpose of the present invention is to achieve uniform distribution and small size of the second phase of the finished aluminum material by adjusting the composition and ratio of alloy elements and fine control of the finished product annealing process in the preparation method, so as to finally prepare a finished aluminum alloy sheet with uniform and small grain size, an average grain size of 10-30um, a reflectivity of 85%, a gloss of 350-420GU, a hardness of HV25-35, and excellent surface performance. After subsequent room temperature stamping and anodizing treatment, the surface color of the aluminum alloy sheet is uniform and free of defects such as spots, which can better meet the technical requirements of high-end products for the appearance decoration surface.

[0006] To achieve the above-mentioned purpose, the technical scheme adopted by the present invention is: a preparation method of a high-gloss anodizable 6xxx aluminum alloy sheet, comprising a smelting and semi-continuous casting step, a homogenization step, a hot rolling step, a cold rolling step and a finished product annealing step performed in sequence. In the finished product annealing step, the plate and strip obtained after cold rolling are coiled and the whole coil is placed in an annealing furnace, the furnace gas temperature is set to 520-600°C, and the temperature is increased to the set temperature at a heating rate of 200-300°C and then kept warm for 0.5-2h. Thereafter, the furnace gas temperature is set to 300-400°C, and the temperature is reduced to the set temperature and then kept warm for 0.5-1h. Finally, the furnace gas temperature is set to 150-250°C, and the temperature is reduced to the set temperature and then kept warm for 0.5-1h. After being taken out of the furnace and cooled, the cooling rate is controlled to be 10-20°C / h. After cooling to room temperature, the finished aluminum alloy sheet is obtained.

[0007] Furthermore, in the smelting and semi-continuous casting steps, the aluminum alloy plate raw material used is composed of the following components in mass percentage: Si is 0.1% to 0.5%; Mg is 0.5% to 1.2%; Ti is 0.01% to 0.04%; Fe is ≤ 0.04%, and the balance is Al and unavoidable impurity elements.

[0008] Furthermore, the content of the impurity elements is ≤0.01%.

[0009] Furthermore, in the smelting and semi-continuous casting steps, the smelting temperature is 730-750°C.

[0010] Furthermore, during the smelting and semi-continuous casting steps, the Ti is added online in the form of Al-Ti-B wires.

[0011] Furthermore, in the smelting and semi-continuous casting steps, the aluminum alloy ingot finally produced has a thickness of 350 to 550 mm and a width of 1000 to 1500 mm.

[0012] Furthermore, in the homogenization step, the temperature of the ingot is 510-530° C., and the holding time is 7-9 hours.

[0013] Furthermore, in the hot rolling step, the starting rolling temperature is 510-520°C, the final rolling temperature is 390-400°C, and the thickness of the hot rolled plate is 9.9-10.1 mm; in the cold rolling step, the thickness of the plate obtained after cold rolling is 1.9-2.1 mm.

[0014] Highly formable anodized 6xxx aluminum alloy sheet, the aluminum alloy sheet has an average grain size of 10 to 30um, a surface roughness of 0.1 to 0.2μm, a reflectivity of ≥85%, a glossiness of 350 to 420GU, and the sheet has a smooth surface and no pitting defects after room temperature stamping, and has no mottled or gray defects on the surface after anodizing.

[0015] Furthermore, the hardness HV of the aluminum alloy plate is 25-35.

[0016] Beneficial effects of the present invention: 1. The high-gloss anodizable 6xxx aluminum alloy sheet of the present invention is prepared by adjusting the alloy element composition and ratio, i.e., Si is 0.1% to 0.5%; Mg is 0.5% to 1.2%; Ti is 0.01% to 0.04%; Fe≤0.04%, and the balance is Al. Combined with a uniquely regulated multi-stage finished product annealing process, the size of the grains in the finished alloy is precisely controlled, and the second phase inside the finished aluminum material is uniformly distributed and small in size, with excellent surface quality and high gloss. After subsequent room temperature stamping and anodizing treatment, the surface color is uniform, without defects such as pitting and spots, and can better meet the technical requirements of high-end products for the appearance of decorative aluminum alloy surfaces, thereby improving the yield of aluminum alloy sheets and strips.

[0017] 2. The preparation method of the high-gloss anodizable 6xxx aluminum alloy sheet of the present invention aims to solve the technical problems that the existing 6xxx aluminum alloy sheet and strip are prone to pitting and cracking defects after room temperature stamping, and the product surface has pitting and serious mottled phenomenon after anodizing. The preparation process of the present invention is to precisely control the specific operation procedures and process parameters of the finished product annealing step, and define the specific operation of the finished product annealing step as follows: the sheet and strip obtained after cold rolling are rolled and the whole roll is placed in an annealing furnace, the furnace gas temperature is set to 520-600°C, and the temperature is increased to the set temperature at a heating rate of 200-300°C and then kept warm for 0.5-2h, then the furnace gas temperature is set to 300-400°C, and the temperature is lowered to the set temperature and kept warm for 0.5-1h, and finally the furnace gas temperature is set to 150-250°C, and the temperature is lowered to the set temperature and kept warm for 0.5-1h, and after cooling out of the furnace, the cooling rate is controlled to be 10-20°C / h. By regulating the finished product annealing process, the cold-rolled deformed structure is promoted to fully recrystallize, and grain refinement is achieved, thereby eliminating the surface mottled defects of the product caused by coarse grains. This is because: the uniform and fine grain structure of the aluminum alloy sheet is of great significance to the quality of the product after subsequent stamping and anodizing. The coarse grains on the surface of the sheet after the finished product annealing will directly affect the surface quality of the product after stamping and anodizing. The present invention can effectively promote the coarse grains in the alloy sheet structure to be refined through recrystallization by regulating the specific operating procedures and process parameters of the finished product annealing step, thereby increasing the number of grain boundaries in the structure, and enhancing the uniformity and consistency of deformation during stamping, thereby avoiding the appearance of micropores at the grain boundaries, thereby effectively avoiding the generation of pitting defects. At the same time, after the refined grains are anodized, they will not show color inhomogeneity due to different grain orientations, thereby avoiding the generation of surface mottled defects, ensuring the quality of the finished product, and reducing the scrap rate.

[0018] 3. The preparation method of the high-gloss anodizable 6xxx aluminum alloy sheet of the present invention, in the finished product annealing step, first set the annealing temperature in a relatively high range of 520 to 600°C. At the relatively high annealing temperature, the compounds at the grain boundaries in the sheet structure will dissolve back into the aluminum matrix, increasing its electrode potential, thereby improving the glossiness of the product surface after anodizing treatment and improving the surface color dull phenomenon. In addition, the multi-stage finished product annealing process of the present application uses a relatively high heating rate during the first-stage annealing, so that the sheet quickly reaches a predetermined temperature and is kept warm for a short time at this temperature, so that the processing structure after cold rolling can be fully recrystallized, while releasing the processing stress of the sheet to obtain a uniform and fine recrystallized grain structure. The subsequent second-stage annealing and third-stage annealing are carried out at relatively low temperatures in sequence. The step-by-step temperature reduction is conducive to avoiding the increase of grains. The multi-stage finished product annealing process effectively avoids the occurrence of stamping cracking problems and ensures product quality. However, the conventional single-pole finished product annealing process system has a low heating rate and a high cooling rate. The grains grow after the deformed structure recrystallizes, and the processing stress in the plate is not completely released, which means that pitting, cracking and spots will appear on the surface after stamping.

[0019] 4. The high-gloss anodized 6xxx aluminum alloy sheet of the present invention, by limiting the composition of the alloy and the mass percentage ratio of each component, makes the alloy components reasonably compatible, comprehensive, and mutually alloyed, thereby significantly improving the comprehensive performance of the 6xxx aluminum alloy material. The finished aluminum alloy sheet has a uniform second phase distribution and small size, an average grain size of 10-30um, a surface roughness of 0.1-0.2μm, a reflectivity of ≥85%, a gloss of 350-420GU, and a hardness of HV25-35, which not only ensures the excellent surface performance of the aluminum alloy sheet, but also achieves the purpose of improving the gloss of the aluminum alloy sheet, and can ensure that the surface color of the aluminum material is bright and uniform after deep drawing and anodizing treatment, without defects such as spots, and meets the technical requirements of high-end products for the appearance of decorative surfaces. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is a metallographic coating photograph of the finished aluminum alloy plate obtained in Example 1; Figure 2 This is a metallographic coating photograph of the finished aluminum alloy plate prepared in Comparative Example 1. DETAILED DESCRIPTION

[0021] In order to make the technical means, creative features, objectives and beneficial effects achieved by the present invention easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and embodiments.

[0022] A high-gloss anodizable 6xxx aluminum alloy sheet, wherein the raw materials of the aluminum alloy sheet and strip are composed of the following components in mass percentage: Si is 0.1% to 0.5%; Mg is 0.5% to 1.2%; Ti is 0.01% to 0.04%; Fe≤0.04%, other impurity elements are ≤0.02%, and the balance is Al; the average grain size of the aluminum alloy sheet is 10 to 30um, the surface roughness is 0.1 to 0.2μm, the reflectivity is ≥85%, the glossiness is 350 to 420GU, the hardness HV is 25 to 35, and the surface of the sheet is smooth and free of pitting defects after room temperature stamping, and the surface is free of mottled and gray defects after anodizing.

[0023] The method for preparing a high-gloss anodizable 6xxx aluminum alloy sheet specifically comprises the following steps: Step 1: Melting and semi-continuous casting According to the above mass percentage ratio, high-purity aluminum ingots, pure magnesium ingots and industrial silicon with a purity higher than 99% are weighed respectively and added in proportion to melt into aluminum liquid. Ti is added online in the form of Al-Ti-B wire. The prepared alloy raw materials are added into a melting furnace at 730-750°C. After melting, semi-continuous casting is carried out to finally produce aluminum alloy ingots with a thickness of 350-550 mm and a width of 1000-1500 mm.

[0024] Step 2: Homogenization First, the aluminum alloy ingot obtained in step ① is added into a homogenization treatment furnace, and the temperature of the aluminum alloy ingot is controlled to be 510-530° C., and the insulation time is 7-9 hours.

[0025] Step 3: Hot rolling The aluminum alloy ingot after homogenization treatment in step ② is directly hot rolled, with the starting rolling temperature being 510-520° C. and the final rolling temperature being 390-400° C., and the thickness of the hot rolled plate finally obtained is 9.9-10.1 mm.

[0026] Step ④: Cold rolling The hot-rolled plate obtained in step ③ is cold-rolled and finally rolled into a plate with a thickness of 1.9 to 2.1 mm.

[0027] Step ⑤: Finished product annealing The plate and strip obtained after cold rolling are coiled and placed in an annealing furnace. The furnace gas temperature is set to 520-600°C, and the temperature is increased to the set temperature at a heating rate of 200-300°C and then kept warm for 0.5-2h. Thereafter, the furnace gas temperature is set to 300-400°C, and the temperature is lowered to the set temperature and then kept warm for 0.5-1h. Finally, the furnace gas temperature is set to 150-250°C, and the temperature is lowered to the set temperature and then kept warm for 0.5-1h. After being taken out of the furnace and cooled, the cooling rate is controlled to 10-20°C / h. After cooling to room temperature, the finished aluminum alloy plate is obtained.

[0028] The method for preparing a high-gloss anodizable 6xxx aluminum alloy plate provided by the present invention promotes sufficient recrystallization of the cold-rolled deformed structure by regulating the finished product annealing process in the preparation process, so as to achieve a finished aluminum alloy plate with uniform and fine grain size, an average grain size of 10-30um, a plate and strip surface roughness of 0.1-0.2μm, a reflectivity of ≥85%, a gloss of 350-420GU, and a hardness of HV25-35, thereby ensuring excellent surface performance of the aluminum alloy plate and strip and achieving the purpose of improving the gloss of the aluminum alloy plate and strip, and ensuring that the surface color of the aluminum material is uniform after deep drawing and anodizing treatment, without defects such as spots and dull colors, and meeting the technical requirements of high-end products for the appearance decorative surface.

[0029] Example 1 The high gloss anodizable 6xxx aluminum alloy plate of this embodiment has the following alloy components in percentage by mass: Si=0.34%, Fe=0.02%, Mg=0.76%, Ti=0.02%, and the remainder of Al and unavoidable impurities.

[0030] The preparation method of the aluminum alloy plate specifically comprises the following steps: S1. Melting and semi-continuous casting: High-purity aluminum ingots with a purity higher than 99%, pure magnesium ingots, and industrial silicon are added in proportion and melted into aluminum liquid. Ti is added online in the form of Al-Ti-B wire. The final preparation specification is an aluminum alloy ingot with a thickness of 450 mm and a width of 1250 mm. The melting temperature is 740°C and the semi-continuous casting temperature is 700°C to obtain the ingot.

[0031] S2. Homogenization treatment: put the ingot into the homogenization treatment furnace, the ingot temperature is 515℃, and keep it warm for 8h.

[0032] S3. Hot rolling: The ingot after homogenization treatment is directly hot rolled, with a starting rolling temperature of 515°C, a final rolling temperature of 400°C, and a hot rolled plate thickness of 10 mm.

[0033] S4, cold rolling: the hot-rolled sheet is continuously cold-rolled to a sheet with a thickness of 2.0 mm.

[0034] S5. Finished product annealing: coil the plate and strip obtained after cold rolling and put the whole coil into an annealing furnace, set the furnace gas temperature to 550°C, heat it to the set temperature at a heating rate of 240°C and keep it warm for 1 hour, then set the furnace gas temperature to 330°C, cool it to the set temperature and keep it warm for 0.5 hour, finally set the furnace gas temperature to 200°C, cool it to the set temperature and keep it warm for 0.5 hour, after cooling out of the furnace, control the cooling rate to 15°C / h, and after cooling to room temperature, the finished aluminum alloy plate is obtained.

[0035] Figure 13 is a metallographic coating photograph of the finished aluminum alloy plate obtained in this embodiment.

[0036] The average grain size of the finished aluminum alloy plate prepared in this embodiment is measured to be 10.3um, the surface roughness Ra=0.13μm, the glossiness is 402GU, and the hardness HV is 29.3. As can be seen from the figure, the plate has fine grains, and there is no pitting defect on the surface after stamping. The surface color of the product after anodizing treatment is uniform, without defects such as spots and dull colors.

[0037] Example 2 The high gloss anodizable 6xxx aluminum alloy plate of this embodiment has the following alloy components in percentage by mass: Si=0.5%, Fe=0.03%, Mg=0.50%, Ti=0.04%, and the remainder of Al and unavoidable impurities.

[0038] The preparation method of the aluminum alloy plate specifically comprises the following steps: S1. Melting and semi-continuous casting: High-purity aluminum ingots with a purity higher than 99%, pure magnesium ingots, and industrial silicon are added in proportion and melted into aluminum liquid. Ti is added online in the form of Al-Ti-B wire. The final preparation specification is an aluminum alloy ingot with a thickness of 550 mm and a width of 1250 mm. The melting temperature is 750°C and the semi-continuous casting temperature is 700°C to obtain the ingot.

[0039] S2. Homogenization treatment: put the ingot into the homogenization treatment furnace, the ingot temperature is 510°C, and keep it warm for 9 hours.

[0040] S3. Hot rolling: The ingot after homogenization treatment is directly hot rolled, with a starting rolling temperature of 520°C, a final rolling temperature of 400°C, and a hot rolled plate thickness of 9.9 mm.

[0041] S4, cold rolling: the hot-rolled sheet is continuously cold-rolled to a sheet with a thickness of 2.1 mm.

[0042] S5. Finished product annealing: coil the plate and strip obtained after cold rolling and put the whole coil into an annealing furnace, set the furnace gas temperature to 520°C, heat it to the set temperature at a heating rate of 200°C and keep it warm for 2 hours, then set the furnace gas temperature to 300°C, cool it to the set temperature and keep it warm for 0.7 hours, finally set the furnace gas temperature to 150°C, cool it to the set temperature and keep it warm for 1 hour, after cooling out of the furnace, control the cooling rate to 20°C / h, and after cooling to room temperature, the finished aluminum alloy plate is obtained.

[0043] The average grain size of the finished aluminum alloy plate prepared in this embodiment is measured to be 24.9um, the surface roughness Ra=0.19μm, the glossiness is 421GU, and the hardness HV is 25.7. The plate has fine grains, and there is no pitting defect on the surface after stamping. The surface color of the product after anodizing treatment is uniform, without defects such as spots and dull colors.

[0044] Example 3 The high gloss anodizable 6xxx aluminum alloy sheet of this embodiment has the following alloy components in percentage by mass: Si=0.1%, Fe=0.04%, Mg=1.2%, Ti=0.01%, and the remainder of Al and unavoidable impurities.

[0045] The preparation method of the aluminum alloy plate specifically comprises the following steps: S1. Melting and semi-continuous casting: High-purity aluminum ingots with a purity higher than 99%, pure magnesium ingots, and industrial silicon are added in proportion and melted into aluminum liquid. Ti is added online in the form of Al-Ti-B wire. The final preparation specification is an aluminum alloy ingot with a thickness of 350 mm and a width of 1250 mm. The melting temperature is 730°C and the semi-continuous casting temperature is 700°C to obtain the ingot.

[0046] S2. Homogenization treatment: put the ingot into the homogenization treatment furnace, the ingot temperature is 530°C, and keep it warm for 7 hours.

[0047] S3. Hot rolling: The ingot after homogenization treatment is directly hot rolled, with a starting rolling temperature of 510°C, a final rolling temperature of 390°C, and a hot rolled plate thickness of 10.1 mm.

[0048] S4, cold rolling: the hot-rolled sheet is continuously cold-rolled to a sheet with a thickness of 1.9 mm.

[0049] S5. Finished product annealing: coil the plate and strip obtained after cold rolling and put the whole coil into an annealing furnace, set the furnace gas temperature to 600℃, heat it to the set temperature at a heating rate of 300℃ and keep it warm for 0.5h, then set the furnace gas temperature to 400℃, cool it to the set temperature and keep it warm for 1h, finally set the furnace gas temperature to 250℃, cool it to the set temperature and keep it warm for 0.5h, after cooling out of the furnace, control the cooling rate to 10℃ / h, and after cooling to room temperature, the finished aluminum alloy plate is obtained.

[0050] The average grain size of the finished aluminum alloy plate prepared in this embodiment is measured to be 27.2um, the surface roughness Ra=0.16μm, the glossiness is 359GU, and the hardness HV is 27.8. The plate has fine grains, and there is no pitting defect on the surface after stamping. The surface color of the product after anodizing treatment is uniform, without defects such as spots and dull colors.

[0051] Comparative Example 1 The alloy composition and preparation process of this embodiment are the same as those of embodiment 1. Only in the finished product annealing process, the plate and strip material is put into the heat treatment furnace in a whole coil, the furnace gas is set to 500°C, the temperature is kept for 3 hours, the heating rate is 150°C / h, and then it is directly taken out of the furnace for cooling, and the cooling rate is 25°C / h. The other preparation process parameters are the same as those of embodiment 1.

[0052] Figure 2 This is a metallographic coating photo of the finished aluminum alloy plate obtained in this embodiment. It can be seen from the figure that the internal structure is fine and coarse, and the number of grain boundaries is small.

[0053] The average grain size of the finished aluminum alloy plate prepared in this embodiment is measured to be 43.4um, the hardness is HV49.7, the reflectivity is 81%, and the glossiness is 315GU. There are pitting defects on the surface of the plate after stamping. After anodizing, there are pitting and severe mottled phenomenon on the surface of the product.

[0054] This is because: the uniform and fine grain structure of aluminum alloy sheet is of great significance to the quality of products after subsequent stamping and anodizing. The coarse grains on the surface of the sheet after annealing will directly affect the surface quality of the product after stamping and anodizing. Because the coarse grains in the sheet structure will reduce the number of grain boundaries, the deformation uniformity and consistency during stamping will be reduced, so that micropores will appear at the grain boundaries, showing pitting defects; after anodizing, the coarse grains will show color difference after reflection due to their respective grain orientations, showing surface mottled defects.

[0055] In addition, during the annealing process of the finished product, the annealing temperature is high, and the compounds at the grain boundaries in the plate structure can be dissolved back into the aluminum matrix, increasing its electrode potential, thereby improving the glossiness of the surface of the product after anodizing treatment and improving the gray surface color phenomenon; the multi-stage finished product annealing system adopted in this patent uses a higher heating rate at the same time, so that the plate quickly reaches the predetermined temperature and is kept warm for a short time at a lower temperature, which can make the processing structure after cold rolling fully recrystallize, and release the processing stress of the plate at the same time, obtain a uniform and fine recrystallized grain structure, and avoid the problem of stamping cracking. However, the conventional single-pole finished product annealing process system has a low heating rate and a high cooling rate. After the deformed structure recrystallizes, the grains grow, and at the same time, the processing stress in the plate is not completely released, that is, pitting and even cracking and mottled will appear on the surface after stamping.

[0056] In the above description, the statistical method of average grain size: refer to the standard "GB / T 6394-2017 Metal Average Grain Size Test Method" to conduct grain size analysis.

[0057] Testing and analysis standards for the surface roughness of aluminum alloy plates: Refer to the standard "GB / T3191-2010 Aluminum Alloy Material Comprehensive Product Standard" for roughness analysis.

[0058] Test and analysis standards for reflectivity and glossiness of aluminum alloy plates: Refer to the standard "GB / T 20503-2006 Determination of specular reflectivity and specular gloss of anodized aluminum and aluminum alloys at 20°, 45°, 60°, and 85° angles" for reflectivity analysis.

[0059] The above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit the same. Those skilled in the art should understand that the specific implementation modes of the present invention may be modified or replaced by equivalents with reference to the above embodiments. Any modifications or equivalent replacements that do not depart from the spirit and scope of the present invention are within the scope of protection of the pending claims.

Claims

1. A method for preparing a high-gloss anodizable 6xxx aluminum alloy sheet, comprising a smelting and semi-continuous casting step, a homogenization step, a hot rolling step, a cold rolling step and a finished product annealing step, characterized in that: In the finished product annealing step, the plate and strip material obtained after cold rolling is coiled and placed in an annealing furnace. The furnace gas temperature is first set to 520-600°C, and the temperature is increased to the set temperature at a heating rate of 200-300°C and then kept warm for 0.5-2h. Thereafter, the furnace gas temperature is set to 300-400°C, and the temperature is lowered to the set temperature and then kept warm for 0.5-1h. Finally, the furnace gas temperature is set to 150-250°C, and the temperature is lowered to the set temperature and then kept warm for 0.5-1h. After being taken out of the furnace and cooled, the cooling rate is controlled to 10-20°C / h. After cooling to room temperature, the finished aluminum alloy plate is obtained.

2. The method for preparing a high gloss anodizable 6xxx aluminum alloy sheet according to claim 1, characterized in that: In the smelting and semi-continuous casting steps, the aluminum alloy plate raw material used is composed of the following components in mass percentage: Si is 0.1% to 0.5%; Mg is 0.5% to 1.2%; Ti is 0.01% to 0.04%; Fe is ≤ 0.04%, and the balance is Al and unavoidable impurity elements.

3. The method for preparing a high gloss anodizable 6xxx aluminum alloy sheet according to claim 2, characterized in that: The content of the impurity elements is ≤0.01%.

4. The method for preparing a high gloss anodizable 6xxx aluminum alloy sheet according to claim 1, characterized in that: In the melting and semi-continuous casting steps, the melting temperature is 730-750°C.

5. The method for preparing a high gloss anodizable 6xxx aluminum alloy sheet according to claim 1, characterized in that: During the melting and semi-continuous casting steps, the Ti is added online in the form of Al-Ti-B wires.

6. The method for preparing a high gloss anodizable 6xxx aluminum alloy sheet according to claim 1, characterized in that: In the smelting and semi-continuous casting steps, the aluminum alloy ingot finally produced has a thickness of 350 to 550 mm and a width of 1000 to 1500 mm.

7. The method for preparing a high gloss anodizable 6xxx aluminum alloy sheet according to claim 1, characterized in that: In the homogenization step, the temperature of the ingot is 510-530° C., and the holding time is 7-9 hours.

8. The method for preparing a high gloss anodizable 6xxx aluminum alloy sheet according to claim 1, characterized in that: In the hot rolling step, the starting rolling temperature is 510-520°C, the final rolling temperature is 390-400°C, and the thickness of the hot rolled plate is 9.9-10.1 mm; in the cold rolling step, the thickness of the plate obtained after cold rolling is 1.9-2.1 mm.

9. A highly formable anodizable 6xxx aluminum alloy sheet prepared according to the method of any one of claims 1 to 8, characterized in that: The average grain size of the aluminum alloy plate is 10-30um, the surface roughness is 0.1-0.2μm, the reflectivity is ≥85%, the glossiness is 350-420GU, and the surface of the plate is smooth and free of pitting defects after room temperature stamping, and the surface is free of spots and gray color defects after anodizing.

10. The high gloss anodizable 6xxx aluminum alloy sheet according to claim 9, characterized in that: The hardness HV of the aluminum alloy plate is 25-35.

Images