An aluminum alloy sheet and strip suitable for anodizing and a method of making the same

Abstract

An aluminum alloy sheet and strip suitable for anodizing is disclosed. The raw material of this aluminum alloy sheet and strip comprises the following components by mass percentage: 0.4%≤Fe<0.8%, 0.8%<Mn<1.3%, 0.02%≤Si<0.2%, Mg≤0.03%, Cr≤0.03%, Zn≤0.03%, 0.01%≤Ti≤0.02%, with the balance being Al, and Si / Fe≤0.25, 1.5%≤Fe+Mn<1.9%. The preparation method optimizes the casting and homogenization processes to control the composition, size, and distribution of the second-phase compounds in the aluminum material, suppressing the formation of AlFeMnSi phases. Through surface roughness control of hot and cold rolling rolls and matching of rolling processes, the finished product exhibits low surface roughness and high gloss after anodizing, ensuring a bright and defect-free surface and improving the yield of the aluminum material.

Description

Technical Field

[0001] This invention belongs to the field of aluminum alloy material technology, specifically a 3xxx series aluminum alloy sheet and strip suitable for anodizing treatment and its preparation method. Background Technology

[0002] Aluminum alloys, with their advantages of light weight, high strength, good plasticity, and excellent anodizing performance, have been widely used in many sectors of the national economy. In recent years, they have seen increasing adoption in building decoration, electrical appliance panels, and food preparation tools. These applications require aluminum alloys to possess not only good strength and formability but also excellent anodizing performance, ensuring a uniform and consistent surface color without discolored spots or streaks. This has become a crucial factor affecting the yield rate and application promotion of aluminum materials.

[0003] 3xxx series aluminum alloys possess excellent comprehensive properties, including moderate strength, good formability, and uniform surface color after anodizing. However, their high alloying degree results in coarse compounds, leading to numerous surface defects after anodizing, low gloss, and a tendency to form discolored spots or even streaks on the surface, resulting in low yields. Therefore, there is an urgent need to develop higher-performance aluminum materials to overcome the many shortcomings of existing materials. Summary of the Invention

[0004] The technical objective of this invention is to prepare an aluminum alloy sheet / strip with uniform internal structure, high consistency, low surface roughness, high gloss, bright and defect-free surface after anodizing, excellent comprehensive performance, and high yield by adjusting the composition and ratio of alloying elements and improving the preparation process and operation. This will meet the technical requirements for aluminum alloy sheet / strip in building decoration, electrical appliance panels, and other fields.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is: an aluminum alloy sheet and strip suitable for anodizing treatment, wherein the raw material of the aluminum alloy sheet and strip is composed of the following components by mass percentage: 0.4%≤Fe<0.8%, 0.8%<Mn<1.3%, 0.02%≤Si<0.2%, Mg≤0.03%, Cr≤0.03%, Zn≤0.03%, 0.01%≤Ti≤0.02%, with the balance being Al and unavoidable impurity elements; and Si / Fe≤0.25, 1.5%≤Fe+Mn<1.9%.

[0006] Furthermore, the surface roughness of the aluminum alloy sheet / strip is 0.15–0.25 μm, the reflectivity is ≥85%, and the gloss is ≥360 GU.

[0007] Furthermore, the aluminum alloy sheet and strip, after anodizing treatment, has no discolored spots or streaks on its surface, a surface roughness of 0.25–0.35 μm, and a surface gloss ≥300 GU.

[0008] Furthermore, the waste material accounts for ≥85% of the raw material by mass; and the proportion of primary waste is ≥40%, the proportion of secondary waste is ≥45%, and the proportion of tertiary and quaternary waste is ≤10%.

[0009] A method for preparing aluminum alloy sheet and strip suitable for anodizing treatment includes the following steps: Step ①: According to the above mass percentage, weigh each component of the raw material for preparing aluminum alloy sheet and strip and place them in a melting furnace. Melt them into liquid aluminum alloy at a temperature of 740-760℃. Then, semi-continuously cast the liquid aluminum alloy into aluminum alloy ingots for later use. Step 2: First, the aluminum alloy ingot obtained in Step 1 is subjected to head and tail trimming and milling. Then, it is placed in a heat treatment furnace for homogenization treatment. During the process, the furnace gas temperature is controlled at 660℃ during the heating process of the heat treatment furnace. When the aluminum alloy ingot is heated to 510℃, the furnace gas temperature is adjusted to 560℃~610℃ and held for 6~24h. Then, the furnace gas temperature is controlled at 520℃. When the aluminum alloy ingot is cooled to 510~540℃, it is held for no less than 8h, and the furnace exit temperature of the aluminum alloy ingot is controlled at ≥485℃. Step ③: Hot-roll the aluminum alloy ingot after homogenization treatment in step ② to obtain hot-rolled slabs for later use; Step 4: Cold roll the hot-rolled slab obtained in step 3, and perform intermediate annealing during the cold rolling process. Control the temperature of intermediate annealing to be 300-370℃ and the holding time to be 12-24h to obtain the finished aluminum alloy sheet and strip.

[0010] Furthermore, in step ①, the casting temperature during semi-continuous casting is 690–710℃, the stable production speed of aluminum alloy ingots is 43–60 mm / min, and the cooling water flow rate in a single crystallizer is 40–65 m³ / min. 3 / h, the temperature of the cooling water is 13~26℃.

[0011] Furthermore, in step ③, the roughness of the hot rolling roll is 0.6 to 1.4 μm.

[0012] Furthermore, in step ③, the initial rolling temperature during hot rolling is 450–520℃, the final rolling temperature is 260–320℃, and the thickness of the hot-rolled slab is 6–10 mm.

[0013] Furthermore, in step ④, the roughness of the cold rolling roll is 0.25 to 0.35 μm.

[0014] Furthermore, in step ④, intermediate annealing is performed when the material is cold-rolled to a thickness of 0.8 to 2 mm, and the thickness of the finished aluminum alloy sheet / strip is 0.5 to 1.5 mm.

[0015] The beneficial effects of this invention are: 1. This invention provides an aluminum alloy sheet and strip suitable for anodizing treatment. Using industrial waste as the main raw material, a unique alloy composition design is employed: 0.4%≤Fe<0.8%, 0.8%<Mn<1.3%, 0.02%≤Si<0.2%, Mg≤0.03%, Cr≤0.03%, Zn≤0.03%, 0.01%≤Ti≤0.02%, with the balance being Al and unavoidable impurity elements; and Si / Fe≤0.25, 1.5%≤Fe+Mn<1.9%. Combined with a special homogenization process and specific steps such as cold rolling, the composition, size, and distribution of the second-phase compounds in the alloy are effectively controlled, resulting in excellent surface quality, high reflectivity and gloss of the finished aluminum alloy. Furthermore, the surface is bright and defect-free after anodizing treatment, thereby improving the yield of the aluminum alloy sheet and strip.

[0016] 2. This invention provides an aluminum alloy sheet and strip suitable for anodizing treatment. By limiting the composition of the alloy and the mass percentage of each component, the alloy components are rationally matched and work together, resulting in mutual alloying, thereby significantly improving the overall performance of 3xxx series aluminum alloy materials. The finished aluminum alloy sheet and strip has a thickness of 0.5–1.5 mm, a surface roughness of 0.15–0.25 μm, a reflectivity ≥85%, a gloss ≥360 GU, and high internal structural uniformity. After anodizing treatment, the surface of the aluminum alloy sheet and strip is free of discolored spots and streaks, with a surface roughness of 0.25–0.35 μm and a gloss ≥300 GU, exhibiting excellent overall performance.

[0017] 3. The present invention provides a preparation process for aluminum alloy sheets and strips suitable for anodizing treatment. By controlling the chemical composition of 3xxx series aluminum alloys and optimizing the melting and semi-continuous casting processes, the composition, size, and distribution of the second-phase compounds are effectively regulated, and Al is suppressed. 12 The formation of the (FeMn)3Si phase eliminates the excessively coarse Al6(FeMn) phase, ensuring excellent surface quality of the aluminum material. After anodizing, the surface is bright and defect-free, thereby improving the yield of aluminum materials. The surface roughness of the aluminum material is 0.15~0.25μm, the reflectivity is ≥85%, and the gloss is ≥360GU.

[0018] 4. A preparation process for aluminum alloy sheet and strip suitable for anodizing treatment according to the present invention, by controlling the homogenization process, suppresses the Al6(FeMn) phase towards Al during homogenization. 12The (FeMn)3Si phase transformation ensures that the finished aluminum alloy sheet and strip have a bright surface without spots or streaks after anodizing, thus improving the yield of aluminum alloy sheet and strip.

[0019] 5. The present invention provides a preparation process for aluminum alloy sheet and strip suitable for anodizing treatment. By controlling the surface roughness of hot rolling and cold rolling rolls and matching the rolling process, the surface roughness after anodizing treatment is improved to 0.25~0.35μm, and the surface gloss is increased to more than 300GU. This ensures that the aluminum material has a bright and defect-free surface after anodizing treatment, meeting the technical requirements for aluminum alloy sheet and strip used in building decoration, electrical appliance panels, and other fields. Attached Figure Description

[0020] Figure 1 These are scanning electron microscope images of the longitudinal section of the finished aluminum alloy sheet and strip obtained in Example 1; Figure 2 These are scanning electron microscope images of the longitudinal section of the finished aluminum alloy sheet and strip obtained in Example 2; Figure 3 The image shows a scanning electron microscope (SEM) image of the longitudinal section of the finished aluminum alloy sheet and strip obtained in Comparative Example 1. Figure 4 The image shows a scanning electron microscope (SEM) image of the longitudinal section of the finished aluminum alloy sheet and strip obtained in Comparative Example 3. Figure 5 These are photographs of the surface of the finished aluminum alloy sheet and strip obtained in Example 1 after anodizing treatment; Figure 6 This is a photograph of the surface of the finished aluminum alloy sheet and strip obtained in Comparative Example 1 after anodizing treatment. Detailed Implementation

[0021] To make the technical means, creative features, objectives, and beneficial effects of this invention easier to understand, the invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0022] An aluminum alloy sheet / strip suitable for anodizing is provided. The raw material of the aluminum alloy sheet / strip consists of the following components by mass percentage: 0.4%≤Fe<0.8%, 0.8%<Mn<1.3%, 0.02%≤Si<0.2%, Mg≤0.03%, Cr≤0.03%, Zn≤0.03%, 0.01%≤Ti≤0.02%, with the balance being Al and unavoidable impurity elements; and Si / Fe≤0.25, 1.5%≤Fe+Mn<1.9%. The surface roughness of the aluminum alloy sheet / strip is 0.15~0.25μm, reflectivity ≥85%, and gloss ≥360GU. After anodizing, the surface of the aluminum alloy sheet / strip is free of discolored spots and streaks, with a surface roughness of 0.25~0.35μm and a surface gloss ≥300GU.

[0023] A method for preparing aluminum alloy sheet and strip suitable for anodizing treatment specifically includes the following steps: Step ①: Smelting and Semi-continuous Casting According to the above-mentioned mass percentage ratio, the raw materials for preparing aluminum alloy sheet and strip were weighed separately, and the prepared aluminum alloy raw materials were added to a melting furnace at 740~760℃, and uniformly mixed and melted into liquid aluminum alloy. Then, the liquid aluminum alloy was semi-continuously cast into aluminum alloy ingots. The temperature during semi-continuous casting was 690~710℃, the stable production speed of ingots was 43~60mm / min, and the cooling water flow rate of a single crystallizer was 40~65m³ / min. 3 / h, cooling water temperature 13~26℃; In this step, the aluminum alloy raw materials used include scrap materials accounting for ≥85% of the total material weight, Grade I scrap (including 3xxx alloy ingots, hot-rolled plate ends and tails, thick plate scrap, etc.) accounting for ≥40%, Grade II scrap (including 3xxx alloy thin plate scrap and trimmed scrap, etc.) accounting for ≥45%, Grade III and IV scrap (including recycled 3xxx alloy scrap after consumption) accounting for ≤10%, and the remaining raw materials are mainly industrial pure aluminum and intermediate alloys of elements such as Al-Mn and Al-Fe, or Fe and Mn fluxes.

[0024] Step 2: Homogenization First, the aluminum alloy ingots obtained in step ① are subjected to head and tail trimming and milling. Then, they are placed in a box-type heat treatment furnace for homogenization treatment. During the process, the furnace gas temperature is controlled at 660℃ during the heating process of the heat treatment furnace. When the aluminum alloy ingot is heated to 510℃, the furnace gas temperature is adjusted to 560℃~610℃ and held for 6~24h. Then, the furnace gas temperature is controlled at 520℃. When the aluminum alloy ingot is cooled to 510~540℃, it is held for ≥8h, and the furnace exit temperature of the aluminum alloy ingot is controlled at ≥485℃.

[0025] Step ③, Hot Rolling The aluminum alloy ingot after homogenization treatment in step ② is rolled into a hot-rolled slab of 6~10mm in a hot continuous rolling process. The roughness of the hot rolling roll is selected as 0.6~1.4um, the initial rolling temperature is 450~520℃, and the final rolling temperature is 260~320℃.

[0026] Step 4: Cold rolling The hot-rolled slab obtained in step ③ is subjected to continuous cold rolling. The roughness of the cold rolling roll is selected to be 0.25~0.35um. When the thickness is 0.8~2mm, intermediate annealing is carried out at a temperature of 300~370℃ for 12~24h. After that, cold rolling is continued to produce a cold-rolled sheet with a thickness of 0.5~1.5mm, which is the finished aluminum alloy sheet and strip.

[0027] This invention discloses a process for preparing aluminum alloy sheet and strip suitable for anodizing. Through smelting and semi-continuous casting, homogenization treatment, hot rolling, and cold rolling (intermediate annealing), 0.5-1 mm thick 3xxx series aluminum alloy sheet and strip are produced. During the process, the composition, size, and distribution of the second-phase compounds in the aluminum are effectively controlled through smelting and semi-continuous casting, suppressing the formation of the AlFeMnSi phase. Simultaneously, by controlling the surface roughness of the hot and cold rolling rolls and matching the rolling process, the surface of the aluminum is ensured to be bright and defect-free after anodizing, improving the yield of the aluminum. Ultimately, the surface roughness after anodizing is achieved to be 0.25-0.35 μm, and the surface gloss is improved to over 300 GU, ensuring a bright and defect-free surface and improving the yield of the aluminum, thus meeting the technical requirements for aluminum alloy sheet and strip used in building decoration, electrical appliance panels, and other fields.

[0028] Example 1 This embodiment provides an aluminum alloy sheet / strip suitable for anodizing treatment, the raw material of which consists of the following components by mass percentage: Fe=0.56%; Mn=1.2%; Si=0.08%; Mg=0.02%; Cr=0.02%; Zn=0.01%; Ti=0.018%, and the balance being Al and unavoidable impurities.

[0029] The method for preparing aluminum alloy sheet and strip specifically includes the following steps: (1) Smelting and semi-continuous casting: According to the above mass percentage ratio, the raw materials for preparing aluminum alloy sheet and strip are weighed respectively, of which primary waste accounts for 45%, secondary waste accounts for 47%, and tertiary and quaternary waste accounts for 5%, with the remainder being aluminum ingots and intermediate alloys. The prepared aluminum alloy raw materials are added to the smelting furnace, and the smelting temperature is controlled at 750℃. The melt is refined and degassed by blowing high-purity Ar gas into the melt with Na-free granular refining agent. Online filtration is carried out using a plate-type double-stage filtration method. After being smelted into liquid aluminum alloy, the liquid aluminum alloy is semi-continuously cast into aluminum alloy ingots. The temperature during semi-continuous casting is 694℃, the stable production speed of ingots is 58mm / min, and the cooling water flow rate of a single crystallizer is 61m³. 3 / h, cooling water temperature 25℃.

[0030] (2) Homogenization treatment: After the aluminum alloy ingot is cut off, the upper and lower surfaces are milled by 15mm. Then, it is placed in a box-type heat treatment furnace for homogenization treatment. The furnace gas is set to 660℃ during the heating process. When the aluminum alloy ingot is heated to 510℃, the furnace gas temperature is adjusted to 610℃ and held for 8 hours. Then the furnace gas temperature is set to 520℃. When the aluminum alloy ingot temperature drops to 520℃, the holding time is 12 hours, and the furnace exit temperature of the aluminum alloy ingot is controlled to be 500℃.

[0031] (3) Hot rolling: The roughness of the hot rolling roll is selected as 0.7um, the initial rolling temperature is 495℃, and the final rolling temperature is 285℃. The homogenized aluminum alloy ingot is rolled into a hot-rolled slab with a thickness of 8.5mm in the hot continuous rolling process.

[0032] (4) Cold rolling: The roughness of the cold rolling roll is selected as 0.27. The thickness of the hot-rolled 8.5mm plate is reduced to 2mm and then intermediate annealed at 335℃ for 15h. After that, cold rolling is continued until the finished product thickness is 1.45mm, thus obtaining the finished aluminum alloy plate and strip.

[0033] Figure 1 In this embodiment, a semi-continuous casting temperature of 694℃, a casting speed of 58mm / min, and a cooling water flow rate of 61m³ / min for a single crystallizer are used. 3 Scanning electron microscope (SEM) images of the longitudinal sections of finished aluminum alloy sheets and strips produced by the casting process of 3xxx series aluminum alloy ingots prepared by the casting process at a cooling water temperature of 25℃ and a cooling water temperature of 25℃.

[0034] Those skilled in the art will know that 3xxx series aluminum alloys mainly contain two Fe-containing phases: Al6(Fe,Mn) phase and Al... 12 The Al6(Fe,Mn) phase, also known as the Al6(Fe,Mn) phase, is massive or rod-shaped with sharp edges and relatively large size. 12 The (Fe,Mn)3Si phase is granular with rounded edges. Literature indicates that the Al6(Fe,Mn) phase remains unchanged during anodizing and peels off during aluminum substrate corrosion, then is partially incorporated into the oxide film during the subsequent anodizing process; while Al... 12 The (Fe,Mn)3Si phase oxidizes at a slower or similar rate than aluminum during anodic oxidation and is doped or dissolved into the oxide film during diffusion. Therefore, Al 12 The (Fe,Mn)3Si phase can easily cause color differences in the oxide film, forming discolored spots or black streaks.

[0035] Depend on Figure 1 It is evident that the second phase in the aluminum alloy sheet and strip produced by rolling the aluminum alloy ingots prepared using this casting process is primarily composed of a large amount of uniformly distributed Al6(Fe,Mn) phase, with the largest size ≤10µm. In other words, in the aluminum alloy sheet and strip of this embodiment, the second phase is mainly Al6(Fe,Mn) phase, and the second phase is fine and uniform, making it less prone to color differences in the oxide film.

[0036] Figure 5 This is a photograph of the finished aluminum alloy sheet / strip obtained in this embodiment after anodizing. Figure 5 As can be seen, the surface of the board is smooth and free of discolored spots or streaks.

[0037] Measurements show that the surface roughness of the finished aluminum alloy sheet and strip prepared in this embodiment is 0.16 μm, the reflectivity is 89%, and the gloss is 372 GU. After anodizing, the surface is bright without spots or streaks, the surface roughness is 0.27 μm, and the surface gloss is 307 GU, which meets the technical requirements for aluminum alloy sheet and strip used in building decoration, electrical appliance panels, and other fields.

[0038] Example 2 This embodiment provides an aluminum alloy sheet / strip suitable for anodizing treatment, the raw material of which consists of the following components by mass percentage: Fe=0.51%; Mn=1.22%; Si=0.11%; Mg=0.02%; Cr=0.01%; Zn=0.01%; Ti=0.015%, and the balance being Al and unavoidable impurities.

[0039] The method for preparing aluminum alloy sheet and strip specifically includes the following steps: (1) Smelting and semi-continuous casting: According to the above mass percentage ratio, the raw materials for preparing aluminum alloy sheet and strip are weighed respectively, of which primary waste accounts for 42%, secondary waste accounts for 47%, and tertiary and quaternary waste accounts for 8%, with the remainder being aluminum ingots and intermediate alloys. The prepared aluminum alloy raw materials are added to the smelting furnace, and the smelting temperature is controlled at 760℃. The melt is refined and degassed by blowing high-purity Ar gas into the melt with Na-free granular refining agent. Online filtration is carried out using a plate-type two-stage filtration method. After being smelted into liquid aluminum alloy, the liquid aluminum alloy is semi-continuously cast into aluminum alloy ingots. The temperature during semi-continuous casting is 708℃, the stable production speed of ingots is 45mm / min, and the cooling water flow rate of a single crystallizer is 47m³ / min. 3 / h, cooling water temperature 14℃; (2) Homogenization treatment: After the aluminum alloy ingot is cut off, the upper and lower surfaces are milled by 15mm. Then, it is placed in a box-type heat treatment furnace for homogenization treatment. The furnace gas temperature is set to 660℃ during the heating process. When the aluminum alloy ingot temperature reaches 510℃, the furnace gas temperature is adjusted to 600℃ and held for 12 hours. Then the furnace gas temperature is set to 520℃. When the aluminum alloy ingot temperature drops to 520℃, the holding time is 10 hours, and the furnace exit temperature of the aluminum alloy ingot is controlled to be 500℃.

[0040] (3) Hot rolling: The roughness of the hot rolling roll is selected as 1.3um, the initial rolling temperature is 510℃, and the final rolling temperature is 310℃. The homogenized aluminum alloy ingot is rolled into a hot rolled slab with a thickness of 8mm in the hot continuous rolling process.

[0041] (4) Cold rolling: The roughness of the cold rolling roll is selected as 0.33. The 8mm thick plate after hot rolling is thinned to 1.5mm and then annealed in the middle. The annealing temperature is 335℃ and the temperature is held for 16h. After that, cold rolling is continued until the finished product thickness is 1.2mm, and the finished aluminum alloy plate and strip are obtained.

[0042] Figure 2 The image shown in this embodiment is a scanning electron microscope (SEM) image of the longitudinal section of the finished aluminum alloy sheet / strip after rolling, prepared by a homogenization process using a furnace gas temperature setting of 660°C during the heating process, adjusting the furnace gas temperature to 580°C when the temperature reaches 510°C, holding for 12 hours, setting the furnace gas temperature to 520°C, holding for 10 hours when the ingot temperature drops to 520°C, and finally achieving an ingot exit temperature of 500°C.

[0043] Depend on Figure 2 It is evident that the second phase in aluminum alloy sheets produced from ingots prepared using this homogenization process mainly consists of a large amount of uniformly distributed Al6(Fe,Mn) phase and a small amount of Al. 12 (Fe,Mn)3Si phase, longest ≤10µm. Al6(Fe,Mn) phase and Al 12 The (Fe,Mn)3Si phase is a high-temperature insoluble phase and will undergo transformation at certain temperatures: 3Al6(Fe,Mn)+Si→α-Al 12 (Fe, Mn)3Si+6Al Strictly control the homogenization process to prevent the formation of Al6(Fe,Mn) phase-oriented Al during homogenization. 12 The transformation of (Fe,Mn)3Si, thereby inhibiting Al 12 The formation of the (Fe,Mn)3Si phase ensures the surface properties of the finished aluminum alloy sheet and strip after anodizing treatment.

[0044] Measurements show that the surface roughness of the finished aluminum alloy sheet and strip prepared in this embodiment is 0.23 μm, the reflectivity is 88%, and the gloss is 372 GU. After anodizing, the surface is bright without spots or streaks, the surface roughness is 0.34 μm, and the surface gloss is 304 GU, which meets the technical requirements for aluminum alloy sheet and strip used in building decoration, electrical appliance panels, and other fields.

[0045] Example 3 This embodiment provides an aluminum alloy sheet / strip suitable for anodizing treatment, the raw material of which consists of the following components by mass percentage: Fe=0.72%; Mn=0.98%; Si=0.07%; Mg=0.02%; Cr=0.01%; Zn=0.01%; Ti=0.02%, and the balance being Al and unavoidable impurities.

[0046] The method for preparing aluminum alloy sheet and strip specifically includes the following steps: (1) Smelting and semi-continuous casting: According to the above mass percentage ratio, the raw materials for preparing aluminum alloy plates and strips are weighed respectively, of which primary waste accounts for 41%, secondary waste accounts for 45%, and tertiary and quaternary waste accounts for 9%, with the remainder being aluminum ingots and intermediate alloys. The prepared aluminum alloy raw materials are added to the smelting furnace, and the smelting temperature is controlled at 755℃. The melt is refined and degassed by blowing high-purity Ar gas into the melt with Na-free granular refining agent. Online filtration is carried out using a plate-type two-stage filtration method. After being smelted into liquid aluminum alloy, the liquid aluminum alloy is semi-continuously cast into aluminum alloy ingots. The temperature during semi-continuous casting is 690℃, the stable production speed of ingots is 55mm / min, and the cooling water flow rate of a single crystallizer is 65m³ / min. 3 / h, cooling water temperature 19℃; (2) Homogenization treatment: After the aluminum alloy ingot is cut off, the upper and lower surfaces are milled by 15mm. Then, it is placed in a box-type heat treatment furnace for homogenization treatment. The furnace gas is set to 660℃ during the heating process. When the aluminum alloy ingot is heated to 510℃, the furnace gas temperature is adjusted to 510℃ and held for 15h. Then the furnace gas temperature is set to 520℃. When the aluminum alloy ingot temperature drops to 520℃, the holding time is 12h, and the furnace exit temperature of the aluminum alloy ingot is controlled to be 510℃.

[0047] (3) Hot rolling: The roughness of the hot rolling roll is selected as 0.6um, the initial rolling temperature is 520℃, and the final rolling temperature is 310℃. The homogenized aluminum alloy ingot is rolled into a hot rolled slab with a thickness of 6mm in the hot continuous rolling process.

[0048] (4) Cold rolling: The roughness of the cold rolling roll is selected as 0.3. The 6mm thick plate after hot rolling is thinned to 1mm and then annealed in the middle. The annealing temperature is 320℃ and the heat is held for 20h. After that, cold rolling is continued until the finished product thickness is 0.5mm, and the finished aluminum alloy plate and strip are obtained.

[0049] Measurements showed that the surface roughness of the finished aluminum alloy sheet and strip prepared in this embodiment was 0.2 μm, the reflectivity was 89%, and the gloss was 369 GU. After anodizing, the surface was bright without spots or streaks, the surface roughness was 0.31 μm, and the surface gloss was 303 GU, which met the technical requirements for aluminum alloy sheet and strip used in building decoration, electrical appliance panels, and other fields.

[0050] Example 4 This embodiment provides an aluminum alloy sheet / strip suitable for anodizing treatment, the raw material of which consists of the following components by mass percentage: Fe=0.77%; Mn=0.85%; Si=0.18%; Mg=0.01%; Cr=0.01%; Zn=0.03%; Ti=0.016%, and the balance being Al and unavoidable impurities.

[0051] The method for preparing aluminum alloy sheet and strip specifically includes the following steps: (1) Smelting and semi-continuous casting: According to the above mass percentage ratio, the raw materials for preparing aluminum alloy sheet and strip are weighed respectively, of which primary waste accounts for 43%, secondary waste accounts for 46%, and tertiary and quaternary waste accounts for 7%, with the remainder being aluminum ingots and intermediate alloys. The prepared aluminum alloy raw materials are added to the smelting furnace, and the smelting temperature is controlled at 760℃. The melt is refined and degassed by blowing high-purity Ar gas into the melt with Na-free granular refining agent. Online filtration is carried out using a plate-type double-stage filtration method. After being smelted into liquid aluminum alloy, the liquid aluminum alloy is semi-continuously cast into aluminum alloy ingots. The temperature during semi-continuous casting is 710℃, the stable production speed of ingots is 60mm / min, and the cooling water flow rate of a single crystallizer is 40m³. 3 / h, cooling water temperature 22℃; (2) Homogenization treatment: After the aluminum alloy ingot is cut off, the upper and lower surfaces are milled by 15mm. Then, it is placed in a box-type heat treatment furnace for homogenization treatment. The furnace gas temperature is set to 660℃ during the heating process. When the aluminum alloy ingot temperature reaches 510℃, the furnace gas temperature is adjusted to 580℃ and held for 18h. Then the furnace gas temperature is set to 520℃. When the aluminum alloy ingot temperature drops to 540℃, the holding time is 8h, and the furnace exit temperature of the aluminum alloy ingot is controlled at 520℃.

[0052] (3) Hot rolling: The roughness of the hot rolling roll is selected as 1.0um, the initial rolling temperature is 450℃, and the final rolling temperature is 320℃. The homogenized aluminum alloy ingot is rolled into a hot rolling slab with a thickness of 10mm in the hot continuous rolling process.

[0053] (4) Cold rolling: The roughness of the cold rolling roll is selected as 0.25. The 10mm thick sheet after hot rolling is thinned to 2mm and then annealed at 370℃ for 12 hours. After that, cold rolling is continued until the finished product thickness is 1.5mm, thus obtaining the finished aluminum alloy sheet and strip.

[0054] Measurements show that the surface roughness of the finished aluminum alloy sheet and strip prepared in this embodiment is 0.18 μm, the reflectivity is 87%, and the gloss is 364 GU. After anodizing, the surface is bright without spots or streaks, the surface roughness is 0.32 μm, and the surface gloss is 304 GU, which meets the technical requirements for aluminum alloy sheet and strip used in building decoration, electrical appliance panels, and other fields.

[0055] Example 5 This embodiment provides an aluminum alloy sheet / strip suitable for anodizing treatment, the raw material of which consists of the following components by mass percentage: Fe=0.4%; Mn=1.2%; Si=0.02%; Mg=0.03%; Cr=0.03%; Zn=0.01%; Ti=0.01%, and the balance being Al and unavoidable impurities.

[0056] The method for preparing aluminum alloy sheet and strip specifically includes the following steps: (1) Smelting and semi-continuous casting: According to the above mass percentage ratio, the raw materials for preparing aluminum alloy plates and strips are weighed separately, of which primary waste accounts for 42%, secondary waste accounts for 49%, and tertiary and quaternary waste accounts for 5%, with the remainder being aluminum ingots and intermediate alloys. The prepared aluminum alloy raw materials are added to the smelting furnace, and the smelting temperature is controlled at 750℃. The melt is refined and degassed by blowing high-purity Ar gas into the melt with Na-free granular refining agent. Online filtration is carried out using a plate-type two-stage filtration method. After being smelted into liquid aluminum alloy, the liquid aluminum alloy is semi-continuously cast into aluminum alloy ingots. The temperature during semi-continuous casting is 700℃, the stable production speed of ingots is 43mm / min, and the cooling water flow rate of a single crystallizer is 50m³. 3 / h, cooling water temperature 20℃; (2) Homogenization treatment: After the aluminum alloy ingot is cut off, the upper and lower surfaces are milled by 15mm. Then, it is placed in a box-type heat treatment furnace for homogenization treatment. The furnace gas temperature is set to 660℃ during the heating process. When the aluminum alloy ingot temperature reaches 510℃, the furnace gas temperature is adjusted to 560℃ and held for 24 hours. Then the furnace gas temperature is set to 520℃. When the aluminum alloy ingot temperature drops to 530℃, the holding time is 10 hours, and the furnace exit temperature of the aluminum alloy ingot is controlled to be 510℃.

[0057] (3) Hot rolling: The roughness of the hot rolling roll is selected as 1.4 μm, the initial rolling temperature is 470℃, and the final rolling temperature is 260℃. The homogenized aluminum alloy ingot is rolled into a hot rolling slab with a thickness of 7.5 mm in the hot continuous rolling process.

[0058] (4) Cold rolling: The roughness of the cold rolling roll is selected as 0.35. The thickness of the hot-rolled 7.5mm plate is reduced to 0.8mm and then intermediate annealed at 300℃ for 24 hours. After that, cold rolling is continued until the finished product thickness is 1.15mm, thus obtaining the finished aluminum alloy plate and strip.

[0059] Measurements show that the surface roughness of the finished aluminum alloy sheet and strip prepared in this embodiment is 0.15 μm, the reflectivity is 86%, and the gloss is 368 GU. After anodizing, the surface is bright without spots or streaks, the surface roughness is 0.27 μm, and the surface gloss is 312 GU, which meets the technical requirements for aluminum alloy sheet and strip used in building decoration, electrical appliance panels, and other fields.

[0060] Comparative Example 1 An aluminum alloy sheet and strip suitable for anodizing treatment, wherein the raw material contains Fe=0.42%, Si=0.16%, Si / Fe=0.38, and the remaining alloy composition is the same as in Example 1.

[0061] Its preparation process is the same as that in Example 1.

[0062] Figure 3 These are scanning electron microscope (SEM) images of the longitudinal section of the finished aluminum alloy sheet / strip prepared in this embodiment. Figure 3 It is evident that the Al6(Fe,Mn) phase in the plate is relatively large in size and exhibits segregation, resulting in the formation of a large amount of Al in the ingot during the melting and casting process. 12 The (Fe,Mn)3Si phase oxidizes at a slower or similar rate than aluminum during anodizing and is incorporated into the oxide film during diffusion. Therefore, after anodizing, it exhibits numerous black streaks on the surface of the sheet, resulting in poor surface quality. Figure 6 As shown.

[0063] Measurements showed that the finished aluminum alloy sheet and strip prepared in this embodiment had a surface roughness of 0.43 μm, a reflectivity of 59%, and a gloss of 329 GU. After anodizing, the surface roughness was 0.63 μm and the surface gloss was 294 GU, which did not meet the technical requirements for aluminum alloy sheet and strip used in building decoration, electrical appliance panels, and other applications.

[0064] Comparative Example 2 An aluminum alloy sheet and strip suitable for anodizing treatment, wherein the raw material contains Fe=0.52%, Si=0.16%, Si / Fe=0.308, and the remaining alloy composition is the same as in Example 1.

[0065] Its preparation process is the same as that in Example 1.

[0066] According to measurements, the surface roughness of the finished aluminum alloy sheet and strip prepared in this embodiment is 0.43 μm, the reflectivity is 46%, and the gloss is 335 GU. After anodizing, the surface roughness is 0.59 μm and the surface gloss is 291 GU, which does not meet the technical requirements for aluminum alloy sheet and strip used in building decoration, electrical appliance panels, etc.

[0067] Comparative Example 3 An aluminum alloy sheet and strip suitable for anodizing treatment, wherein the alloy composition of the raw material is the same as that in Example 2.

[0068] The homogenization process in the preparation process involves setting the furnace gas temperature to 660°C during the heating process. When the temperature reaches 530°C, the furnace gas temperature is adjusted to 630°C and held for 24 hours. Then, the furnace gas temperature is set to 520°C, and when the ingot temperature drops to 520°C, it is held for 10 hours. The ingot exit temperature is 500°C. Other preparation process conditions are the same as in Example 1.

[0069] Figure 4 These are scanning electron microscope (SEM) images of the longitudinal section of the finished aluminum alloy sheet / strip prepared in this comparative example. Figure 4 It can be seen that the second phase of this plate is mostly Al6(Fe,Mn) phase, with some Al. 12 (Fe,Mn)3Si phase.

[0070] According to measurements, the surface roughness of the finished aluminum alloy sheet and strip prepared in this embodiment is 0.39 μm, the reflectivity is 68%, and the gloss is 348 GU. After anodizing, the surface roughness is 0.48 μm and the surface gloss is 295 GU, which does not meet the technical requirements for aluminum alloy sheet and strip used in building decoration, electrical appliance panels, etc.

[0071] The above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Those skilled in the art should understand that modifications or equivalent substitutions can be made to the specific implementation of the present invention with reference to the above embodiments. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention are within the protection scope of the pending claims.

Claims

1. An aluminum alloy sheet / strip suitable for anodizing treatment, characterized in that, The raw material for this aluminum alloy sheet and strip consists of the following components by mass percentage: 0.4%≤Fe<0.8%, 0.8%<Mn<1.3%, 0.02%≤Si<0.2%, Mg≤0.03%, Cr≤0.03%, Zn≤0.03%, 0.01%≤Ti≤0.02%, with the balance being Al and unavoidable impurity elements; and Si / Fe≤0.25, 1.5%≤Fe+Mn<1.9%; the preparation method of this aluminum alloy sheet and strip includes the following steps: Step ①: According to the above mass percentage, weigh each component of the raw material for preparing aluminum alloy sheet and strip and place them in a melting furnace. Melt them into liquid aluminum alloy at a temperature of 740-760℃. Then, semi-continuously cast the liquid aluminum alloy into aluminum alloy ingots for later use. Step 2: First, the aluminum alloy ingot obtained in Step 1 is subjected to head and tail trimming and milling. Then, it is placed in a heat treatment furnace for homogenization treatment. During the process, the furnace gas temperature is controlled at 660℃ during the heating process of the heat treatment furnace. When the aluminum alloy ingot is heated to 510℃, the furnace gas temperature is adjusted to 560℃~610℃ and held for 6~24h. Then, the furnace gas temperature is controlled at 520℃. When the aluminum alloy ingot is cooled to 510~540℃, it is held for no less than 8h, and the furnace exit temperature of the aluminum alloy ingot is controlled at ≥485℃. Step ③: Hot-roll the aluminum alloy ingot after homogenization treatment in step ② to obtain hot-rolled slabs for later use; Step 4: Cold roll the hot-rolled slab obtained in step 3, and perform intermediate annealing during the cold rolling process. Control the temperature of intermediate annealing to be 300-370℃ and the holding time to be 12-24h to obtain the finished aluminum alloy sheet and strip.

2. The aluminum alloy sheet and strip suitable for anodizing according to claim 1, characterized in that: The aluminum alloy sheet and strip have a surface roughness of 0.15–0.25 μm, a reflectivity of ≥85%, and a gloss of ≥360 GU.

3. The aluminum alloy sheet and strip suitable for anodizing according to claim 1, characterized in that: The aluminum alloy sheet and strip, after anodizing treatment, have no discolored spots or streaks on the surface, a surface roughness of 0.25-0.35μm, and a surface gloss of ≥300GU.

4. The aluminum alloy sheet and strip suitable for anodizing according to claim 1, characterized in that: The raw materials contain ≥85% waste by mass; and the proportion of primary waste is ≥40%, the proportion of secondary waste is ≥45%, and the proportion of tertiary and quaternary waste is ≤10%.

5. A method for preparing aluminum alloy sheet and strip suitable for anodizing according to claim 1 or 4, characterized in that, Includes the following steps: Step ①: According to the above mass percentage, weigh each component of the raw material for preparing aluminum alloy sheet and strip and place them in a melting furnace. Melt them into liquid aluminum alloy at a temperature of 740-760℃. Then, semi-continuously cast the liquid aluminum alloy into aluminum alloy ingots for later use. Step 2: First, the aluminum alloy ingot obtained in Step 1 is subjected to head and tail trimming and milling. Then, it is placed in a heat treatment furnace for homogenization treatment. During the process, the furnace gas temperature is controlled at 660℃ during the heating process of the heat treatment furnace. When the aluminum alloy ingot is heated to 510℃, the furnace gas temperature is adjusted to 560℃~610℃ and held for 6~24h. Then, the furnace gas temperature is controlled at 520℃. When the aluminum alloy ingot is cooled to 510~540℃, it is held for no less than 8h, and the furnace exit temperature of the aluminum alloy ingot is controlled at ≥485℃. Step ③: Hot-roll the aluminum alloy ingot after homogenization treatment in step ② to obtain hot-rolled slabs for later use; Step 4: Cold roll the hot-rolled slab obtained in step 3, and perform intermediate annealing during the cold rolling process. Control the temperature of intermediate annealing to be 300-370℃ and the holding time to be 12-24h to obtain the finished aluminum alloy sheet and strip.

6. The method for preparing aluminum alloy sheet and strip suitable for anodizing according to claim 5, characterized in that: In step 1, the casting temperature during the semi-continuous casting is 690-710℃, the stable production speed of the aluminum alloy ingot is 43-60mm / min, the cooling water flow in the single crystallizer is 40-65m 3 / h, and the temperature of the cooling water is 13-26℃.

7. The method for preparing aluminum alloy sheet and strip suitable for anodizing according to claim 5, characterized in that: In step ③, the roughness of the hot rolling roll is 0.6 to 1.4 μm.

8. The method for preparing aluminum alloy sheet and strip suitable for anodizing according to claim 5, characterized in that: In step ③, the initial rolling temperature during hot rolling is 450–520℃, the final rolling temperature is 260–320℃, and the thickness of the hot-rolled slab is 6–10 mm.

9. A method for preparing aluminum alloy sheet and strip suitable for anodizing according to claim 5, characterized in that: In step ④, the roughness of the cold rolling roll is 0.25 to 0.35 μm.

10. A method for preparing aluminum alloy sheet and strip suitable for anodizing according to claim 5, characterized in that: In step ④, intermediate annealing is performed when the material is cold-rolled to a thickness of 0.8 to 2 mm, and the thickness of the finished aluminum alloy sheet and strip is 0.5 to 1.5 mm.

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