5xxx mirror aluminum and preparation method and application thereof

Abstract

The invention discloses 5xxx mirror aluminum and a preparation method and application thereof, and belongs to the technical field of metal materials. The method comprises the steps that S1, a cast ingot is obtained; s2, carrying out homogenizing heat treatment at the temperature of 550-580 DEG C for 6-8 hours; s3, hot rolling treatment; s4, primary cold rolling treatment; s5, the intermediate annealing treatment temperature is 220-300 DEG C, and heat preservation is conducted for 2-4 h; s6, secondary cold rolling treatment is conducted for 3-4 passes, and the deformation amount is 20%-45%; s7, mirror surface rolling is conducted; s8, finished product annealing treatment is conducted, the temperature is 280-300 DEG C, and heat preservation is conducted for 2-6 h; and S9, anodic oxidation treatment is conducted. According to the mirror aluminum, the proportion of the Cube texture is 0.5-6%, the white line rate is smaller than or equal to 5%, the glossiness is 400-500 GU, the tensile strength is 120-150 MPa, the yield strength is 80-100 MPa, and the ductility is 16-22%.

Description

Technical Field

[0001] This application relates to the field of metallic materials technology, and more specifically, to a 5xxx mirror aluminum, its preparation method, and its application. Background Technology

[0002] High-end automobiles extensively use mirror-finish aluminum products as interior and exterior trim components, leading to a continuous increase in demand for mirror-finish aluminum. Furthermore, as domestically produced mirror-finish aluminum gradually replaces imported materials, higher requirements are being placed on domestically produced mirror-finish aluminum materials used in automobiles. Currently, the white line ratio of imported products is stable at below 3%, while the white line ratio of domestically produced products is unstable, mainly fluctuating between 5% and 10%, which is one of the important reasons affecting the product yield.

[0003] To further improve the quality of domestically produced 5xxx mirror aluminum products and increase the yield rate, it is necessary to optimize the proportion and distribution of cube texture to reduce the generation of material marks; at the same time, reduce the large-size Fe-containing phases in the alloy to reduce the adverse effects of white lines. Summary of the Invention

[0004] The main purpose of this application is to provide a 5xxx mirror aluminum, its preparation method and application, in order to solve the problem of low yield of mirror aluminum after anodizing in the prior art.

[0005] To achieve the above objectives, according to one aspect of this application, a method for preparing 5xxx mirror-finish aluminum is provided, comprising the following steps:

[0006] Step S1: Prepare the raw materials according to the proportions of each element in the 5xxx aluminum alloy and melt and cast them into aluminum alloy ingots;

[0007] Step S2: The ingot is subjected to homogenization heat treatment to obtain a homogenized ingot; wherein, the homogenization heat treatment temperature is 550~580℃ and the holding time of the homogenization heat treatment is 6~8h.

[0008] Step S3: Hot-roll the homogenized ingot to obtain a hot-rolled plate;

[0009] Step S4: Perform a cold rolling process on the hot-rolled plate to obtain a cold-rolled plate;

[0010] Step S5: Perform intermediate annealing on the cold-rolled sheet to obtain an intermediate annealed sheet; wherein, the temperature of the intermediate annealing is 220~300℃, and the holding time of the intermediate annealing is 2~4h;

[0011] Step S6: Perform a second cold rolling process on the intermediate annealed plate to obtain a second cold rolled plate; wherein the number of passes in the second cold rolling process is 3 to 4, the deformation per pass is 20% to 45%, and the rolling speed is 200 to 300 m / min.

[0012] Step S7: Perform mirror rolling on the secondary cold-rolled sheet to obtain the initial mirror aluminum sheet;

[0013] Step S8: Perform finished product annealing on the initial mirror aluminum plate to obtain 5xxx mirror aluminum.

[0014] Further, in step S1, the content of each element in the 5xxx aluminum alloy includes: Mg 0.6%~1.0%, Fe 0.08%~0.12%, Cr≤0.08%, Si 0.06~0.12%, the total amount of other impurity elements ≤0.1%, and the balance is Al, totaling 100wt%.

[0015] Furthermore, in step S2, the homogenization heat treatment temperature is 560~580℃, and the holding time for homogenization heat treatment is 7~8h.

[0016] Furthermore, in step S3, the initial rolling temperature of the hot rolling process is 460~480℃, and the final rolling temperature of the hot rolling process is 300~320℃.

[0017] Furthermore, the thickness of the hot-rolled plate is 6~8mm.

[0018] Furthermore, the thickness of the cold-rolled sheet is 3~4mm.

[0019] Furthermore, in step S5, the intermediate annealing temperature is 220~280℃, and the intermediate annealing holding time is 2~3h.

[0020] Furthermore, the thickness of the secondary cold-rolled sheet is 2~3mm.

[0021] Furthermore, in step S7, the mirror rolling process is performed in 3 to 5 passes; wherein the deformation amount of the last pass is ≤10%, and the deformation amount of the remaining passes is 10 to 20%.

[0022] Furthermore, in step S8, the annealing temperature of the finished product is 280~300℃, and the annealing time is 2~6h.

[0023] Furthermore, in step S8, the average grain size of the 5xxx mirror aluminum is 90~120μm, the maximum grain size is ≤160μm, and the Cube texture area accounts for 0.5~6%.

[0024] According to a second aspect of this application, a 5xxx mirror aluminum is provided, which is prepared by the above-described preparation method.

[0025] Furthermore, 5xxx mirror aluminum has a white line ratio of ≤5%, a gloss level of 400~500GU, a tensile strength of 120~150MPa, and a yield strength of 80~100MPa.

[0026] According to a third aspect of this application, 5xxx mirror aluminum obtained by the above preparation method or the application of the above 5xxx mirror aluminum in automotive trim parts is provided.

[0027] Compared with the prior art, this application has the following beneficial effects:

[0028] This application achieves optimal grain structure and texture in finished mirror-finish aluminum sheets through a combined control of high-temperature homogenization, intermediate annealing, and cold rolling processes. Specifically, the high-temperature homogenization process significantly shortens homogenization time, improves production efficiency, and allows the Fe-containing second phase to fully dissolve back into the matrix, reducing the risk of white lines in the finished sheet. Furthermore, increasing the homogenization temperature helps reduce the proportion of cube texture in the hot-rolled sheet and extends this low cube texture structure to subsequent processes. The combined control method of intermediate annealing and cold rolling, using a temperature lower than that of re-annealing... The annealing temperature at the crystallization temperature causes partial recrystallization of the material, achieving the purpose of refining the grains and softening the structure. After intermediate annealing, secondary cold rolling and mirror rolling are performed, which increases the amount of cold deformation after intermediate annealing and fully eliminates the small amount of recrystallized structure generated during intermediate annealing, reducing the recrystallized structure in subsequent processes. Therefore, after low-temperature finished product annealing, the finished mirror aluminum has only a small amount of inherited cube texture and a small amount of newly formed cube texture, which significantly reduces the total cube texture ratio, significantly improves the gloss of 5xxx mirror aluminum material, and reduces the risk of material marks. Attached Figure Description

[0029] The accompanying drawings, which form part of this application, are used to provide a further understanding of this application. The illustrative embodiments and descriptions of this application are used to explain this application and do not constitute an undue limitation of this application. In the drawings:

[0030] Figure 1 Electron backscatter diffraction (EBSD) pattern of 5xxx mirror aluminum finished grains prepared in Example 1 of this application.

[0031] Figure 2 Electron backscatter diffraction (EBSD) pattern of the Cube texture structure of 5xxx mirror aluminum product prepared in Example 1 of this application.

[0032] Figure 3 Electron backscattering diffraction (EBSD) pattern of the 5xxx mirror-finished aluminum grains prepared in Comparative Example 1 of this application.

[0033] Figure 4 The electron backscatter diffraction (EBSD) pattern of the Cube texture structure of the 5xxx mirror aluminum finished product prepared in Comparative Example 1 of this application. Detailed Implementation

[0034] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. The present application will now be described in detail with reference to the embodiments.

[0035] As mentioned in the background technology, the Cube texture accounts for about 10-20% of the 5xxx mirror aluminum used in automobiles, and the white line rate of the product fluctuates between 5-10%, which affects the product yield. In order to further improve the quality of domestic 5xxx mirror aluminum products and increase the product yield, it is necessary to optimize the proportion and distribution of the Cube texture to reduce the generation of material lines; at the same time, reduce the large-size Fe phase in the alloy to reduce the adverse effects of white lines.

[0036] According to one aspect of this application, a method for preparing 5xxx mirror-finish aluminum is provided, comprising the following steps:

[0037] Step S1: Prepare the raw materials according to the proportions of each element in the 5xxx aluminum alloy and melt and cast them into aluminum alloy ingots;

[0038] Step S2: The ingot is subjected to homogenization heat treatment to obtain a homogenized ingot; wherein, the homogenization heat treatment temperature is 550~580℃ and the holding time of the homogenization heat treatment is 6~8h.

[0039] Step S3: Hot-roll the homogenized ingot to obtain a hot-rolled plate;

[0040] Step S4: Perform a cold rolling process on the hot-rolled plate to obtain a cold-rolled plate;

[0041] Step S5: Perform intermediate annealing on the cold-rolled sheet to obtain an intermediate annealed sheet; wherein, the temperature of the intermediate annealing is 220~300℃, and the holding time of the intermediate annealing is 2~4h;

[0042] Step S6: Perform a second cold rolling process on the intermediate annealed plate to obtain a second cold rolled plate; wherein the number of passes in the second cold rolling process is 3 to 4, the deformation per pass is 20% to 45%, and the rolling speed is 200 to 300 m / min.

[0043] Step S7: Perform mirror rolling on the secondary cold-rolled sheet to obtain the initial mirror aluminum sheet;

[0044] Step S8: Perform finished product annealing on the initial mirror aluminum plate to obtain 5xxx mirror aluminum.

[0045] In the preparation method described above in this application, the homogenization heat treatment temperature can be selected from any value of 550℃, 560℃, 570℃, 580℃ or any range between two; the homogenization heat treatment holding time is any value of 6h, 6.5h, 7h, 7.5h, 8h or any range between two; the intermediate annealing temperature can be selected from any value of 220℃, 230℃, 240℃, 250℃, 260℃, 270℃, 280℃, 290℃, 300℃ or any range between two.

[0046] This application achieves optimal grain structure and texture in finished mirror-finish aluminum sheets through a combined control of high-temperature homogenization, intermediate annealing, and cold rolling processes. Specifically, the high-temperature homogenization process significantly shortens homogenization time, improves production efficiency, and allows the Fe-containing second phase to fully dissolve back into the matrix, reducing the risk of white lines in the finished sheet. Furthermore, increasing the homogenization temperature helps reduce the proportion of cube texture in the hot-rolled sheet and extends this low cube texture structure to subsequent processes. The combined control method of intermediate annealing and cold rolling, using an annealing temperature below the recrystallization temperature to induce partial recrystallization, achieves grain refinement and softens the structure. After intermediate annealing… The process involved secondary cold rolling and mirror rolling, which increased the amount of cold deformation after intermediate annealing and effectively eliminated the small amount of recrystallization generated during intermediate annealing, thus reducing the recrystallization of subsequent processes. As a result, after low-temperature finished product annealing, the finished mirror aluminum only has a small amount of inherited cube texture and a small amount of newly formed cube texture, significantly reducing the total cube texture ratio to 0.5-6%, which significantly improves the gloss of 5xxx mirror aluminum material and reduces the risk of material marks. This results in a white line rate of ≤5%, a gloss of 400-500 GU, a tensile strength of 120-150 MPa, a yield strength of 80-100 MPa, and an elongation of 16-22% for 5xxx mirror aluminum.

[0047] To promote the dissolution and uniform distribution of alloying elements, improve the microstructure, and enhance the performance consistency of the product, in some specific embodiments, step S2 involves homogenizing the ingot with heat treatment to obtain a homogenized ingot. The homogenization heat treatment temperature is 560-580℃, and the holding time is 7-8 hours. This application employs the aforementioned 560-580℃ high-temperature homogenization method, which significantly shortens the homogenization time, improves production efficiency, allows the Fe-containing second phase to fully dissolve back into the matrix, and reduces the risk of white lines in the finished sheet. Furthermore, increasing the homogenization temperature helps reduce the proportion of cube texture in the hot-rolled sheet and allows this low cube texture structure to be carried over to subsequent processes.

[0048] In order to further refine the grains, improve the microstructure, control texture growth, and improve material properties, in some specific embodiments, the thickness of the cold-rolled sheet in step S4 is 3~4mm. In step S5, the intermediate annealing temperature is 220~280℃, and the holding time is 2~3h; the thickness of the secondary cold-rolled sheet is 2~3mm, for example, 2.5~3.0mm; by using the combined control of the primary cold rolling process, intermediate annealing process, and secondary cold rolling process, the material texture will change during the primary cold rolling process. Intermediate annealing can "reset" part of the texture. The lower primary cold rolling rate combined with the lower intermediate annealing temperature can suppress recrystallization during the intermediate annealing process, control the proportion of cube texture, and at the same time, a certain annealing temperature allows the intermediate annealing process to fully recover, preventing insufficient recovery due to excessively low temperature, which would result in an excessively narrow annealing window for the finished product. This facilitates the control of the microstructure, mechanical properties, and surface treatment properties of the finished 5xxx mirror aluminum in the finished product annealing stage of industrial production, ensuring that it can meet the requirements of high-standard automotive decorative parts, while improving production efficiency and finished product qualification rate.

[0049] To control grain size, optimize microstructure, and improve processing efficiency, this application further optimizes the temperatures during the initial rolling stage and the final rolling stage. In some specific embodiments, in step S3, the initial rolling temperature for hot rolling is 460~480℃, and the final rolling temperature is 300~320℃. The initial rolling temperature is selected from any value among 460℃, 470℃, and 480℃, or any range between two values. The final rolling temperature can be selected from any value among 300℃, 305℃, 310℃, 315℃, and 320℃, or any range between two values, for example, 300~310℃. The thickness of the hot-rolled plate is 6~8mm. By precisely controlling the hot rolling temperature, especially the final rolling temperature, recrystallization during the hot rolling process can be suppressed, preventing the excessive formation of cube texture, thereby ensuring the surface quality and optical properties of the product after anodizing and improving the yield of 5xxx mirror aluminum.

[0050] To produce mirror-finish aluminum sheets with extremely high surface smoothness and reflectivity, in some specific embodiments, step S7 involves 3 to 5 passes of mirror rolling, with the deformation amount of the last pass ≤10%, and the deformation amount of the remaining passes 10 to 20%. For example, the number of passes is 3 to 4, and the deformation amount of the last pass is 8 to 9%. By implementing 3 to 5 precise mirror cold rolling processes, each rolling operation significantly improves the surface roughness of the sheet. In this series of processes, the high-intensity cold rolling deformation in the first pass aims to remove obvious ripples or unevenness on the sheet surface. As the number of rolling passes increases, the deformation amount gradually decreases. Crucially, the deformation amount in the last pass must be strictly managed and controlled within 10%, primarily to reduce surface roughness and improve gloss.

[0051] To further control the grain structure, improve machinability, reduce white line rate, and increase yield, in some specific embodiments, in step S8, the annealing temperature of the finished product is 280~300℃, and the annealing time is 2~6h; further annealing is performed at 280~290℃ for 2~4h, for example, annealing at 280℃ for 2h. The average grain size of the prepared mirror aluminum plate is 90~120μm, the maximum grain size is ≤160μm, and the cube texture volume ratio is 0.5~6%. If the ratio exceeds 6%, material lines are likely to appear; with the increase of Cr, the gloss is slightly increased; after anodizing treatment, the white line rate of 5xxx mirror aluminum is ≤5%, and the gloss is 400~500GU; the tensile strength of 5xxx mirror aluminum is 120~150MPa, the yield strength is 80~100MPa, and the elongation is 16~22%.

[0052] To produce mirror-finish aluminum products with high gloss and low white line content, a suitable element ratio is selected. In some specific embodiments, in step S1, the element ratio in the initial 5xxx aluminum alloy ingot includes: Mg 0.6%~1.0%, Fe 0.08%~0.12%, Cr≤0.08%, Si 0.06~0.12%, with the total amount of other impurity elements ≤0.1%, and the balance being Al, totaling 100wt%. Specifically, the weight ratio of each element in the ingot is: Mg 1.0%, Fe 0.12%, Cr 0.08%, Si 0.12%, Al 98.63%, and unavoidable impurities. Appropriate raw materials or alloy materials are selected according to the weight ratio of each element; for example, Mg comes from pure magnesium, Fe from iron, chromium from aluminum-chromium alloy, silicon from impurities in pure aluminum ingots, and aluminum from pure aluminum ingots, etc. In the above formulation, the Mg content is controlled at 0.6~1.0%, which is beneficial to improving the mechanical properties of mirror aluminum; the Fe content is controlled at 0.08~0.12% and the Si content is controlled below 0.12%, which avoids the Si and Fe phases from reducing the gloss and at the same time reduces the generation of large-size second phases, thereby reducing the proportion of white lines; the Cr content is controlled below 0.08%, which can moderately improve the gloss of mirror aluminum. By adopting the above-mentioned element ratio and content control, the gloss of mirror aluminum can be improved, the surface white line rate can be reduced, and its good mechanical properties can be ensured.

[0053] According to a second aspect of this application, a 5xxx mirror aluminum is provided, which is prepared by the above-mentioned preparation method; the cube texture volume ratio is 0.5~6%, the white line ratio is ≤5%, the gloss is 400~500GU, the tensile strength is 120~150MPa, the yield strength is 80~100MPa, and the elongation is 16~22%.

[0054] According to a third aspect of this application, a method for preparing the aforementioned 5xxx mirror aluminum is provided, along with the application of the aforementioned 5xxx mirror aluminum in automotive trim parts; these trim parts can be interior or exterior automotive trim parts.

[0055] The present application will be further described in detail below with reference to specific embodiments, which should not be construed as limiting the scope of protection claimed in the present application.

[0056] The raw materials used in the embodiments of this application are all existing technologies and are commercially available.

[0057] Example 1

[0058] A method for preparing 5xxx series mirror-finish aluminum for automobiles includes the following steps:

[0059] Step S1: Prepare raw materials according to the proportions of each element: Mg 1.0%, Fe 0.12%, Cr 0.08%, Si 0.12%, Al 98.63% and unavoidable impurities; melt and cast pure magnesium ingots, iron flux, aluminum-chromium alloy and pure aluminum ingots to obtain aluminum alloy ingots;

[0060] Step S2: The aluminum alloy ingot is subjected to homogenization heat treatment at a temperature of 580℃ for 8 hours to obtain a homogenized ingot.

[0061] Step S3: Hot rolling is performed on the homogenized ingot. The initial hot rolling temperature is 460℃ and the final hot rolling temperature is 300℃ to obtain a hot-rolled plate with a thickness of 8mm.

[0062] Step S4: Perform a cold rolling process on the hot-rolled plate to obtain a cold-rolled plate with a thickness of 3mm;

[0063] Step S5: Place the cold-rolled sheet in an annealing furnace and hold it at 220℃ for 2 hours for intermediate annealing treatment to obtain an intermediate annealed sheet;

[0064] Step S6: Perform a second cold rolling process on the intermediate annealed plate to obtain a second cold rolled plate with a thickness of 2.1 mm; the second cold rolling process is performed in 3 passes, with deformation amounts of 28%, 25%, and 20% per pass, respectively, and a rolling speed of 200 m / min.

[0065] Step S7: Perform mirror rolling on the secondary cold-rolled sheet in 3 passes. The deformation amount in the first pass is 19%, the deformation amount in the second pass is 15%, and the deformation amount in the third pass is 9%, to obtain the initial mirror aluminum sheet.

[0066] Step S8: The initial mirror aluminum plate is annealed at 280℃ for 2 hours to obtain the finished mirror aluminum.

[0067] Step S9: The finished mirror-finished aluminum is sequentially subjected to alkaline washing, neutralization, electrochemical polishing, anodizing, and sealing; the anodizing process conditions include: voltage 15V, oxidation time 30min, and oxidation temperature 16℃; the grain structure of the finished 5xxx mirror-finished aluminum is as follows: Figure 1 Cube texture as Figure 2 As shown.

[0068] Example 2

[0069] The difference between Example 2 and Example 1 is that the homogenization heat treatment temperature in step S2 is replaced with 550°C and the holding time is 6 hours.

[0070] Example 3

[0071] The difference between Example 3 and Example 1 is that the initial rolling temperature of the hot rolling process in step S3 is replaced with 480°C, and the final rolling temperature is 320°C.

[0072] Example 4

[0073] The difference between Example 4 and Example 1 is that the intermediate annealing temperature in step S5 is replaced with 280°C and the holding time is 3 hours.

[0074] Example 5

[0075] The difference between Example 5 and Example 1 is that the intermediate annealing temperature in step S5 is replaced with 300°C and the holding time is 4 hours.

[0076] Example 6

[0077] The difference between Example 6 and Example 1 is that the number of passes in the secondary cold rolling process in step S6 is replaced with 4 passes, the deformation amount of the first pass is 28%, the deformation amount of the second pass is 25%, the deformation amount of the third pass is 22%, the deformation amount of the fourth pass is 20%, and the rolling speed is 300m / min; thus, a secondary cold-rolled plate is obtained.

[0078] Example 7

[0079] The difference between Example 7 and Example 1 is that the number of mirror rolling passes in step S7 is replaced with 5 passes, the deformation amount of the first pass is 18%, the deformation amount of the second pass is 15%, the deformation amount of the third pass is 13%, the deformation amount of the fourth pass is 11%, and the deformation amount of the fifth pass is 8%, thus obtaining the initial mirror aluminum plate.

[0080] Example 8

[0081] The difference between Example 8 and Example 1 is that the annealing temperature of the finished product in step S8 is replaced with 300°C and the annealing time is 6 hours.

[0082] Comparative Example 1

[0083] The difference between Comparative Example 1 and Example 1 is that the homogenization heat treatment temperature in step S2 was replaced with 590°C; the resulting finished mirror-finished aluminum grain structure is as follows: Figure 3 Cube texture as Figure 4 As shown.

[0084] Comparative Example 2

[0085] The difference between Comparative Example 2 and Example 1 is that the homogenization heat treatment temperature in step S2 is replaced with 460°C.

[0086] Comparative Example 3

[0087] The difference between Comparative Example 3 and Example 1 is that the intermediate annealing temperature in step S5 is replaced with 320°C and the holding time is 5 hours.

[0088] Comparative Example 4

[0089] The difference between Comparative Example 4 and Example 1 is that the intermediate annealing temperature in step S5 is replaced with 200°C and the holding time is 2 hours.

[0090] Performance testing:

[0091] The properties of the 5xxx mirror aluminum prepared in each embodiment and comparative example were tested using the following methods, and the results are shown in Table 1.

[0092] (1) The average particle size and cube structure ratio of the mirror aluminum products were detected by scanning electron microscopy;

[0093] (2) Use a gloss meter to test the gloss of mirror aluminum products and observe the surface texture with the naked eye;

[0094] (3) The tensile strength, yield strength and elongation of the mirror aluminum products were tested using a 10t tensile tester.

[0095] Table 1

[0096]

[0097] Table 1 shows that the average grain size of the finished mirror aluminum prepared in each embodiment of this application is 90~120μm, the maximum grain size is ≤160μm, the volume ratio of cube texture is 0.5~6%, the white line rate is ≤5%, the mirror aluminum surface is free of material texture, the gloss reaches 400~500GU, the tensile strength is 120~150MPa, the yield strength is 80~100MPa, and the elongation is 16~22%.

[0098] In Comparative Examples 1 to 4, the homogenization heat treatment temperature was too high or too low, the intermediate annealing temperature was too high or too low, and recrystallization was easy to occur when only one cold rolling was performed, resulting in larger grains, increased cube texture ratio, decreased surface gloss, increased white line rate on the surface, and diagonal lines.

[0099] The above comparison shows that this application, through the combined control of high-temperature homogenization-intermediate annealing-cold rolling processes, achieves optimal grain structure and texture in the finished mirror aluminum sheet. Specifically, the high-temperature homogenization process significantly shortens the homogenization time, improves production efficiency, and allows the Fe-containing second phase to fully dissolve back into the matrix, reducing the risk of white lines in the finished sheet. Furthermore, increasing the homogenization temperature helps reduce the proportion of cube texture in the hot-rolled sheet and extends this low cube texture proportion to subsequent processes. The combined control method of intermediate annealing and cold rolling, wherein... Annealing at temperatures below the recrystallization temperature causes partial recrystallization of the material, achieving the purpose of refining grains and softening the microstructure. Furthermore, secondary cold rolling and mirror rolling are performed after intermediate annealing, increasing the amount of cold deformation after intermediate annealing and effectively eliminating the small amount of recrystallized microstructure generated during intermediate annealing, thus reducing recrystallization in subsequent processes. Therefore, after low-temperature finished product annealing, the finished mirror aluminum has only a small amount of inherited cube texture and a small amount of newly formed cube texture, significantly reducing the overall cube texture ratio, significantly improving the gloss of 5xxx mirror aluminum material, and reducing the risk of grain marks.

[0100] It should be noted that the terms "first," "second," etc., used in the specification and claims of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such terms can be used interchangeably where appropriate so that the embodiments of this application described herein can be implemented, for example, in a sequence other than those described herein.

[0101] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A method for preparing 5xxx mirror-finish aluminum, characterized in that, The preparation method includes the following steps: Step S1: Prepare the raw materials according to the proportions of each element in the 5xxx aluminum alloy and melt and cast them into aluminum alloy ingots; Step S2: The ingot is subjected to homogenization heat treatment to obtain a homogenized ingot; wherein, the temperature of the homogenization heat treatment is 550~580℃, and the holding time of the homogenization heat treatment is 6~8h. Step S3: The homogenized ingot is hot-rolled to obtain a hot-rolled plate; Step S4: Perform a cold rolling process on the hot-rolled plate to obtain a cold-rolled plate; Step S5: Perform intermediate annealing on the cold-rolled sheet to obtain an intermediate annealed sheet; wherein, the temperature of the intermediate annealing is 220~300℃, and the holding time of the intermediate annealing is 2~4h; Step S6: Perform a secondary cold rolling process on the intermediate annealed plate to obtain a secondary cold rolled plate; wherein the secondary cold rolling process is performed in 3 to 4 passes, the deformation per pass is 20% to 45%, and the rolling speed is 200 to 300 m / min. Step S7: Perform mirror rolling on the secondary cold-rolled sheet to obtain an initial mirror aluminum sheet; Step S8: Perform finished product annealing on the initial mirror aluminum plate to obtain the 5xxx mirror aluminum.

2. The method for preparing 5xxx mirror aluminum according to claim 1, characterized in that, In step S1, the content of each element in the 5xxx aluminum alloy includes: Mg 0.6%~1.0%, Fe 0.08%~0.12%, Cr≤0.08%, Si 0.06~0.12%, the total amount of other impurity elements ≤0.1%, and the balance is Al, totaling 100wt%.

3. The method for preparing 5xxx mirror aluminum according to claim 1 or 2, characterized in that, In step S2, the temperature of the homogenization heat treatment is 560~580℃, and the holding time of the homogenization heat treatment is 7~8h.

4. The method for preparing 5xxx mirror aluminum according to any one of claims 1 to 3, characterized in that, In step S3, the initial rolling temperature of the hot rolling process is 460~480℃, and the final rolling temperature of the hot rolling process is 300~320℃. And / or, the thickness of the hot-rolled plate is 6~8mm; And / or, the thickness of the primary cold-rolled sheet is 3~4mm.

5. The method for preparing 5xxx mirror aluminum according to any one of claims 1 to 4, characterized in that, In step S5, the temperature of the intermediate annealing treatment is 220~280℃, and the holding time of the intermediate annealing treatment is 2~3h. And / or, the thickness of the secondary cold-rolled sheet is 2~3mm.

6. The method for preparing 5xxx mirror aluminum according to any one of claims 1 to 5, characterized in that, In step S7, the mirror rolling process is performed in 3 to 5 passes; wherein the deformation amount of the last pass is ≤10%, and the deformation amount of the remaining passes is 10 to 20%.

7. The method for preparing 5xxx mirror aluminum according to any one of claims 1 to 6, characterized in that, In step S8, the temperature of the finished product annealing treatment is 280~300℃, and the annealing time of the finished product annealing treatment is 2~6h; And / or, in step S8, the average grain size of the 5xxx mirror aluminum is 90~120μm, the maximum grain size is ≤160μm, and the Cube texture area accounts for 0.5~6%.

8. A 5xxx mirror-finish aluminum, characterized in that, It is prepared using the preparation method of 5xxx mirror aluminum according to any one of claims 1 to 7.

9. The 5xxx mirror aluminum according to claim 8, characterized in that, The white line ratio of the 5xxx mirror aluminum is ≤5%, and the gloss is 400~500GU; the tensile strength of the 5xxx mirror aluminum is 120~150MPa, the yield strength is 80~100MPa, and the elongation is 16~22%.

10. The application of the 5xxx mirror aluminum obtained by the preparation method of any one of claims 1 to 7, or the 5xxx mirror aluminum according to claim 8 or 9, in automotive trim parts.

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