A method for preparing anodized aluminum alloy strip and aluminum alloy strip

Abstract

The present invention relates to the technical field of aluminum alloy strip preparation, and mentions a method for preparing an aluminum alloy strip for anodized appearance and an aluminum alloy strip, wherein the preparation method comprises: after melting the raw aluminum and the intermediate metal, a semi-continuous casting method is adopted to obtain an ingot, the ingot is sawed and milled, and then the ingot is hot-rolled to obtain a coil; the hot-rolled coil is cold-rolled for 1 to 7 passes to obtain a rolled material of a preset thickness, and the contact arc length L of the rolling deformation zone of each pass satisfies the absolute deformation amount △H of L≤10×△H. The cold-rolled rolled material is subjected to a stretching and straightening process to obtain a finished product. The present application effectively controls the mechanical properties of the strip and the consistency of the longitudinal section grains by controlling the process conditions such as the component composition, hot rolling and cold rolling processes, so that the growth of the oxide film and the unevenness of the oxide film corrosion in the cross-section anodizing process are effectively controlled, thereby playing a positive role in ensuring the cross-section anodizing effect.

Description

Technical Field

[0001] The invention relates to the technical field of aluminum alloy strip preparation, and in particular to a method for preparing an aluminum alloy strip for anodized appearance and the aluminum alloy strip. Background Art

[0002] Aluminum alloy has become the preferred material for electronic product casings due to its light weight, good heat dissipation, beautiful color difference after anodizing and coloring, and high surface hardness. With the promotion and application of Huawei's large-size ultra-thin TVs and all-in-one computers, reducing the thickness of aluminum alloy strips will greatly reduce production costs.

[0003] For electronic products such as mobile phone back shells and tablet back shells, their aluminum alloy shells only serve to provide aesthetics and strength for the back shells. There is no need to provide rigidity for the screen frame to protect the overall rigidity of the electronic products. Therefore, there are no thickness and strength requirements for the four frames after stamping, and generally 0.5~1.0mm 5-series aluminum alloy strips are used; while for large-size TVs and all-in-one shells, the four frames obtained after stamping are required to have sufficient strength to support the weight of the screen and avoid screen damage under conditions where the four sides are stressed. Therefore, the aluminum shells for large-size TVs and all-in-one computer back shells are processed with 2.0~3.0mm 5-series aluminum alloy strips. On the one hand, this can ensure that the frame is thick enough to provide strength, and on the other hand, this thickness can be used to process enough screen fixing buckles. The 1.5mm thick 5252 alloy anodized material used by Huawei, Honor and other brands on laptops is stamped and the four frames are upset to successfully increase the frame thickness to more than 2.0mm. Due to the poor surface quality after upsetting, it is necessary to perform surface CNC (Computer Numerical Control) processing to have a good flatness. However, the CNC-processed products show obvious bright line defects after anodizing, which seriously restricts the mass production application of this process. Summary of the invention

[0004] 1. Technical issues to be resolved

[0005] In view of the existing technology, products processed from aluminum alloy strips show obvious bright line defects after anodizing, which seriously restricts their mass production and application.

[0006] (II) Technical solution

[0007] To this end, the first aspect of the present invention mentions a method for preparing an anodized aluminum alloy strip for appearance, comprising:

[0008] Step 1: melt the raw aluminum and the intermediate metal, analyze the composition of the molten material, treat the melt quality, and then use semi-continuous casting to obtain an ingot;

[0009] Step 2: After sawing and milling the ingot, the ingot is heated evenly, and then the ingot is taken out of the furnace and hot-rolled to obtain a coil;

[0010] Step 3: The hot-rolled coil is cold-rolled for 1 to 7 passes to obtain a rolled material of a preset thickness, and the contact arc length L of the rolling deformation zone in each pass and the absolute deformation amount △H satisfy L≤10×△H.

[0011] Step 4: The cold-rolled material to a preset thickness is subjected to a stretching, bending and straightening process to obtain a finished product.

[0012] Furthermore, in step 2, the process conditions for equalization are to control the temperature at 480-520° C. for 8-20 hours.

[0013] Furthermore, in step 2, the hot rolling includes: hot rough rolling, during which the absolute deformation of a single hot rolling pass before the ingot passes through a hot rough rolling outlet with a thickness of ≥120 mm is no less than 40 mm.

[0014] Furthermore, in step 2, the hot rolling process further includes: hot finishing rolling. During the hot finishing rolling process, the deformation amount of the ingot after hot rough rolling in a single pass of hot finishing rolling is not less than 40%.

[0015] Furthermore, in step 2, the final rolling temperature of the hot rolling is 320-360° C., and the thickness of the obtained coil is 2.0-5.0 mm.

[0016] Furthermore, in step 3, the total deformation of the hot-rolled coil after cold rolling is controlled to be above 20%.

[0017] Furthermore, the raw aluminum includes: scrap aluminum or aluminum ingots.

[0018] Furthermore, in step 4, the elongation parameter of the stretch bending and straightening process is set to 0.3-0.8%.

[0019] The second aspect of the present invention relates to an anodized aluminum alloy strip for appearance, which is made by the method for preparing an anodized aluminum alloy strip for appearance as described in the first aspect above;

[0020] Taking the sum of weight percentage as 100%, the composition and content of the aluminum alloy strip are: Si≤0.06%, Fe≤0.35%, Cu≤0.1%, Cr≤0.35%, Ti≤0.02%, Mn content is 0.10~0.50%, Mg content is 2.0~3.5%, and the balance is Al and various non-negligible impurities.

[0021] Furthermore, taking the sum of the weight percentages as 100%, the content of each impurity is ≤0.03%, and the total weight of the impurities does not exceed 0.15% of the total weight of the aluminum alloy strip.

[0022] (III) Beneficial effects

[0023] The beneficial effects of the present invention are as follows: the present invention provides a method for preparing an aluminum alloy strip for anodized appearance and an aluminum alloy strip, wherein the preparation method comprises: step 1: melting raw aluminum and intermediate metal, analyzing the composition of the melted material, treating the melt quality, and obtaining an ingot by semi-continuous casting; step 2: sawing and milling the ingot and then heating it, and then hot-rolling the ingot out of the furnace to obtain a coil; step 3: cold-rolling the hot-rolled coil for 1 to 7 passes to obtain a rolled material of a preset thickness, and the contact arc length L of the rolling deformation zone of each pass and the absolute deformation △H satisfy L≤10×△H. Step 4: The rolled material cold-rolled to a preset thickness is subjected to a stretching, bending and straightening process to obtain a finished product.

[0024] The present application effectively controls the mechanical properties of the strip and the consistency of the longitudinal grains by controlling the process conditions such as component composition, hot rolling and cold rolling processes, so that the unevenness of oxide film growth and oxide film corrosion in the cross-section anodizing process is effectively controlled, thereby playing a positive role in ensuring the cross-section anodizing effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is a surface condition diagram of the longitudinal section of the anodized aluminum alloy strip prepared in Example 1 after anodization treatment;

[0026] Figure 2 This is a surface condition diagram of the longitudinal section of the 5252 aluminum alloy strip prepared in Comparative Example 1 after anodizing;

[0027] Figure 3 This is a grain morphology diagram of the 5252 aluminum alloy strip prepared in Comparative Example 1 on a thickness section;

[0028] Figure 4 This is a grain morphology diagram of the anodized aluminum alloy strip prepared in Example 1 on a thickness section;

[0029] Figure 5 A schematic diagram of the rolling process of the aluminum alloy strip for anodized appearance prepared in this application;

[0030] Figure 6 The present invention is a process flow chart of a method for preparing an anodized aluminum alloy strip for appearance. DETAILED DESCRIPTION

[0031] In order to better explain the present invention and facilitate understanding, the present invention is described in detail below through specific implementation modes in conjunction with the accompanying drawings.

[0032] When an amount, concentration, or other value or parameter is expressed as a range, a preferred range, or a range limited by a series of upper preferred values ​​and lower preferred values, this should be understood as specifically disclosing all ranges formed by any pairing of any range upper limit or preferred value with any range lower limit or preferred value, regardless of whether the range is disclosed separately. For example, when a range of "1 to 5" is disclosed, the described range should be interpreted as including ranges of "1 to 4", "1 to 3", "1 to 2", "1 to 2 and 4 to 5", "1 to 3 and 5", etc. When a numerical range is described in this article, unless otherwise stated, the range is intended to include its end values ​​and all integers and fractions within the range.

[0033] In these embodiments, unless otherwise specified, the parts and percentages are all by mass. "Parts by mass" refers to the basic unit of measurement representing the mass ratio of multiple components, and 1 part can represent any unit mass, such as 1 g, 3.527 g, etc. If we say that the mass parts of component A are a parts and the mass parts of component B are b parts, it means the ratio of the mass of component A to the mass of component B a:b. Alternatively, it means that the mass of component A is aK and the mass of component B is bK (K is an arbitrary number, indicating a multiple factor). It should not be misunderstood that, unlike the mass parts, the sum of the mass parts of all components is not limited to 100 parts. "And / or" is used to indicate that one or both of the situations described may occur, for example, A and / or B include (A and B) and (A or B).

[0034] It should be noted that aluminum is widely used in the outer shell parts of various products due to its light weight, high surface hardness after anodizing and bright colors after coloring. Increasing the strength of aluminum will be able to improve its rigidity and durability after forming.

[0035] This application takes the 5 series alloy with medium strength as the starting point, optimizes the alloy composition, increases the rolling deformation in the hot rolling process, increases the final rolling temperature, and limits the relationship between the cold rolling deformation zone length and the cold rolling deformation to obtain an aluminum alloy strip.

[0036] refer to Figure 6 The first aspect of the present application mentions a method for preparing an anodized aluminum alloy strip for appearance, which is used to prepare an anodized aluminum alloy strip for appearance as described in the first aspect, comprising:

[0037] Step 1: melt the raw aluminum and the intermediate metal, analyze the composition of the molten material, treat the melt quality, and then use semi-continuous casting to obtain an ingot;

[0038] It should be noted that the raw aluminum can be scrap aluminum or aluminum ingots, and the intermediate metal can be one or more of Al-10Si, Al-10Fe, Al-50Cu, Al-10Mn, pure Mg, pure Zn or Al-5Ti.

[0039] Step 2: After sawing and milling the ingot, the ingot is heated evenly, and then the ingot is taken out of the furnace and hot-rolled to obtain a coil;

[0040] In the technical solution, in step 2, the process conditions of the soaking process are to control the temperature at 480-520°C for 8-20 hours.

[0041] It should be noted that the hot rolling process includes: hot rough rolling and hot finishing rolling, which are carried out in sequence. During the hot rough rolling process, the absolute deformation of the hot rolling single pass before the ingot passes through the hot rough rolling outlet with a thickness of ≥120mm is not less than 40mm. During the hot finishing rolling process, the deformation of the ingot after hot rough rolling in a single pass of hot finishing rolling is not less than 40%.

[0042] In the technical solution, in step 2, the final rolling temperature of hot rolling is 320-360° C., and the thickness of the obtained coil is 2.0-5.0 mm.

[0043] It should be noted that before the thickness of the ingot after hot rough rolling is ≥120mm, that is, before the thickness of the hot rolled intermediate billet is less than or equal to 120mm, controlling the absolute deformation will be beneficial to the full crushing of the grains and the crushing of coarse compounds. The subsequent control of the hot finishing rolling deformation and the hot finishing rolling temperature will, on the one hand, be beneficial to further crushing the grains. On the other hand, it is easier to obtain a uniform structure for the grains and compounds in the thickness direction, providing conditions for obtaining a more uniform internal structure after cold rolling.

[0044] The present invention emphasizes in the hot rolling process that when the thickness of the rough rolling outlet is above 120 mm, the absolute deformation of each rolling pass must be above 40 mm; in the cold rolling process, it is further emphasized that the length of the rolling deformation zone and the absolute deformation must be strictly arranged according to the principle of L≤10×△H. The purpose is to make the elongation deformation speeds of the surface metal and the core metal in the deformation process of the aluminum plate and strip tend to be consistent under the condition of large reduction deformation.

[0045] Step 3: cold rolling the hot-rolled coil for 1 to 7 passes to obtain a rolled material with a preset thickness;

[0046] refer to Figure 5 , where L is the contact arc length between the rolling deformation zone and the roller, i.e. the thick line part in the figure, △H=H2-H1, where H2 represents the initial thickness of the coil and H1 represents the thickness of the coil after rolling.

[0047] In the technical solution, in step 3, in the process of cold rolling passes, the contact arc length L of the rolling deformation zone of each pass and the absolute deformation amount △H satisfy L≤10×△H.

[0048] In the technical solution, in step 3, the total deformation of the hot-rolled coil after cold rolling is controlled to be above 20%.

[0049] It should be noted that strict control of the cold rolling process is an important condition for achieving uniform distribution of grains and second phases in the longitudinal section. The contact arc length L and the absolute deformation △H of the rolling deformation zone in each pass must satisfy L≤10×△H. This is to reduce the contact area of ​​the surface deformation zone, which is more conducive to the transmission of rolling force in the thickness direction, thereby making the grain uniformity in the thickness direction better.

[0050] In order to achieve the effect of no banded color difference after anodizing of any section, the present invention carries out special control on the hot rolling and cold rolling processes: for the hot rolling process, due to the large thickness and the alloy being rolled and deformed above the recrystallization temperature, giving a single pass of more than 40 mm absolute deformation will ensure that the surface metal and the core metal are stretched and deformed together, ensuring that the surface grains and the core grains are similar in size; for the cold rolling process, due to the thin thickness and the alloy being rolled and deformed at room temperature far below the recrystallization temperature of 360°C, the purpose of controlling the contact arc length L and the absolute deformation △H to satisfy L≤10×△H is to allow the rolling force to penetrate the aluminum plate, promote the same-frequency extension of the core grains and the surface grains, and avoid the situation in which the surface metal is stretched more and the core grains are stretched less in the general rolling process.

[0051] In order to achieve the synchronous tensile deformation of the core grains and the surface grains as described above, the present invention uses a small diameter roller for rolling under the same deformation amount. Generally, a roller with a diameter of 160-250 mm is used to replace a conventional roller with a diameter of 380-460 mm for rolling.

[0052] It should be noted that, by controlling the matching relationship among the hot rolling deformation, the cold rolling deformation zone length L and the absolute deformation △H, the cross-sectional anode appearance quality of the product is not affected by the Fe content and the cold rolling deformation, thereby further reducing the production cost.

[0053] Step 4: The cold-rolled material to a preset thickness is subjected to a stretching, bending and straightening process to obtain a finished product.

[0054] In the technical solution, in step 4, the elongation parameter of the stretching and straightening process is set to 0.3-0.8%.

[0055] In summary, the present application effectively controls the mechanical properties of the strip and the consistency of the longitudinal grains by controlling the process conditions such as component composition, hot rolling and cold rolling processes, so that the unevenness of oxide film growth and oxide film corrosion in the cross-section anodizing process is effectively controlled, thereby playing a positive role in ensuring the cross-section anodizing effect.

[0056] The preparation method of the aluminum alloy strip provided by the present invention can obtain a 5-series alloy aluminum plate strip having good anode appearance quality in any section in the thickness direction without using high-purity aluminum or sufficient cold rolling deformation in the production process. Since high-purity aluminum, multiple cold rolling deformation and heat treatment are not required, the production cost is better controlled. By controlling the cold rolling deformation, the aluminum alloy strip has better mechanical properties. When the product manufactured by the present invention is applied to the rear shell of a large-size TV and the shell of an all-in-one computer, the thickness of the existing plate can be reduced, which is more energy-saving and environmentally friendly, while further reducing the cost.

[0057] In order to better understand the technical solution, exemplary embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. Although exemplary embodiments of the present invention are shown in the accompanying drawings, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided to enable a clearer and more thorough understanding of the present invention and to fully convey the scope of the present invention to those skilled in the art.

[0058] Example 1

[0059] The aluminum alloy strip prepared in Example 1 has the following composition and content: Si: 0.04wt%, Fe: 0.15wt%, Cu: 0.05wt%, Mn: 0.12wt%, Mg: 2.0wt%, Cr: 0.18wt%, Ti: 0.02wt%, and the remainder is Al and other impurities generated during the manufacturing process. The content of each impurity is ≤0.03%, and the total amount of impurities does not exceed 0.15%.

[0060] The preparation method comprises the following steps:

[0061] After the raw aluminum and master alloy are smelted, they are double filtered by a plate filter and a deep bed filter, and then semi-continuously cast to obtain an ingot of 400×1320 mm;

[0062] The obtained ingot is sawn and milled before entering the heating furnace, and then hot rolled at 520℃ / 8h. Before the hot rolled intermediate billet is rolled to 120mm, the thickness (mm) of each hot rough rolling pass is as follows:

[0063] 400-350-300-250-200-160-120;

[0064] The thickness of each pass of hot finishing rolling (mm) is: 16.0-9.0-5.0-3.0;

[0065] The hot rolling final rolling temperature is 360°C, and a hot rolled coil with a thickness of 3.0 mm is obtained;

[0066] The 3.0 mm coil is thinned to 1.5 mm by one cold rolling, and then the finished product is obtained by stretching, bending and straightening.

[0067] The above-mentioned cold rolling is performed by using a φ100mm roller, the cold rolling deformation is 50%, and the rolling arc length L of one pass is 12.2mm (12.2<10×1.5), satisfying L≤10×△H; the rolled coil is stretched, bent and straightened to obtain the finished product;

[0068] The thickness of the aluminum plate and strip produced is 1.5 mm, the tensile strength of the product is 220 MPa, the yield strength is 160 MPa, the elongation is 12.4%, and there is no strip defect on the cross section after anodizing.

[0069] Example 2

[0070] The aluminum alloy strip prepared in Example 2 has the following composition and content: Si: 0.06wt%, Fe: 0.35wt%, Cu: 0.1wt%, Mn: 0.50wt%, Mg: 3.5wt%, Cr: 0.35wt%, Ti: 0.02wt%, and the remainder is Al and other impurities generated during the manufacturing process. The content of each impurity is ≤0.03%, and the total amount of impurities does not exceed 0.15%.

[0071] The preparation method comprises the following steps:

[0072] After the raw aluminum and master alloy are smelted, they are double filtered through a plate filter and a deep bed filter, and then semi-continuously cast to obtain an ingot of 650×1450 mm;

[0073] The obtained ingot is sawn and milled before entering the heating furnace, and then hot rolled at 480℃ / 20h. Before the hot rolled intermediate billet is rolled to 120mm, the thickness (mm) of each hot rough rolling pass is as follows:

[0074] 650-590-530-470-410-350-290-230-180;

[0075] The rolling thickness (mm) of each pass of hot finishing rolling is: 32.0-17.0-9.0-5.0;

[0076] The hot rolling final rolling temperature is 360°C, and a hot rolled coil with a thickness of 5.0 mm is obtained;

[0077] The 5.0 mm thick hot-rolled coil is thinned to 1.6 mm by two cold rolling processes, the first cold rolling process is thinned to 3.0 mm, and the second cold rolling process is thinned to 1.6 mm, and then the finished product is obtained by stretching, bending and straightening.

[0078] The above-mentioned cold rolling is performed by using a φ100 mm roller, and the arc lengths L of the two passes are 10.0 mm (12.0 < 10 × 2.0) and 8.4 mm (8.4 < 10 × 1.4), respectively, both satisfying L ≤ 10 × △H; the coil after cold rolling is stretched, bent and straightened to obtain the finished product;

[0079] The thickness of the aluminum sheet strip produced is 1.6 mm, the tensile strength of the product is 295 MPa, the yield strength is 210 MPa, the elongation is 8.6%, and there is no bright line defect on the cross section after anodizing.

[0080] Comparative Example 1

[0081] The 5252 aluminum alloy strip prepared in Comparative Example 1 has an alloy composition and content of Si: 0.05wt%, Fe: 0.08wt%, Cu: 0.08wt%, Mn: 0.02wt%, Mg: 2.5wt%, Ti: 0.022wt%, and the balance is Al and other impurities generated during the manufacturing process. The content of each impurity is ≤0.03%, and the total amount of impurities does not exceed 0.15%.

[0082] The preparation method comprises the following steps:

[0083] The pure aluminum ingot is fed into a smelting furnace for melting, and an appropriate amount of master alloy is added, and after the composition is adjusted, semi-continuous casting is performed to obtain an ingot of 520×1250 mm;

[0084] The obtained ingot is sawn and milled, and then put into a heating furnace, kept at 470°C for 8 hours, and then taken out of the furnace for hot rolling, with the final hot rolling temperature of 320°C to obtain a hot rolled coil with a thickness of 5.0 mm;

[0085] The hot-rolled coil is first cold-rolled in two passes, each of which is rolled using a φ400mm roller, with a rolling thickness (mm) of "5.0-2.8-1.9" and a total cold rolling reduction of 62%; then, a box furnace is used to perform intermediate annealing at a process condition of 320°C / 20h, followed by cold rolling to 1.5mm, with a cold rolling deformation of 21%; the rolling arc lengths L of the three cold rolling passes are 29.6mm (29.6≮10×2.2), 19mm (19≮10×0.9), and 12.7mm (12.7≮10×0.4), all of which do not satisfy L≤10×△H.

[0086] 4) The finished product is obtained by rolling to the finished thickness and then bending and straightening.

[0087] The thickness of the aluminum alloy strip produced is 1.5 mm, the tensile strength of the product is 208 MPa, the yield strength is 155 MPa, the elongation is 13.6%, and the strip defects are obvious after the cross section is anodic.

[0088] refer to Figure 1 and Figure 2 , Figure 1 and Figure 2 The following are the surface conditions of the cross-section of the aluminum alloy strip prepared in Example 1 and Comparative Example 1 after anodic treatment. Figure 1 and Figure 2 By comparison, it can be seen that the cross section of the aluminum alloy strip prepared by the present invention in the thickness direction has no stripe defects on the surface after anodic treatment, while the aluminum strip prepared by the traditional process has obvious stripe defects on the surface after anodic treatment.

[0089] By comparison Figure 3 and Figure 4 It can be seen that Figure 3 and Figure 4 The grain morphology of the 5252 aluminum alloy strip prepared in comparative example 1 and the aluminum alloy strip prepared in embodiment 1 in the cross section in thickness are shown respectively. The grain size of comparative example 1 is very uneven, wherein the grain length of 150 μm at the core thickness of about 400 μm and the grain length of about 30 μm on the upper and lower surfaces have obvious differences; while the grain size uniformity of embodiment 1 of the present invention in the thickness direction is better, and the grain length of the core and the surface is 80-100 μm. The difficulty of controlling the uniformity of the cross-sectional structure is much greater than that of controlling the uniformity of the surface structure.

[0090] Compared with traditional 5 series alloys, the present invention has made improvements in aluminum ingot composition, ingredient formula, production process, etc. The obtained aluminum alloy strip has good cost control, excellent stamping performance and cross-section anode appearance quality, and is very suitable for the development needs of various industries with complex forming structures that require upsetting, extrusion and CNC processing before anodizing treatment.

[0091] A second aspect of the present invention provides an aluminum alloy strip for anodized appearance. The components and contents of the aluminum alloy strip are as follows, with the sum of the weight percentages being 100%, Si≤0.06%, Fe≤0.35%, Cu≤0.1%, Cr≤0.35%, Ti≤0.02%, Mn content being 0.10~0.50%, Mg content being 2.0~3.5%, and the remainder being Al and a variety of non-negligible impurities.

[0092] In the present technical solution, there are multiple components of the impurities, and taking the sum of the weight percentages as 100%, the content of each impurity is ≤0.03%, and the total weight of the impurities does not exceed 0.15% of the total weight of the aluminum alloy strip.

[0093] The following is an explanation of the reasons for limiting the content of each component and the process:

[0094] Mg: Mg in the alloy is an essential additive element to ensure the strength of the alloy plate. If the Mg content exceeds 3.5%, it will accelerate the uneven distribution of Mg8Al5, thereby causing instability in the anodizing process, which is not conducive to obtaining a good appearance effect.

[0095] Fe: Fe can provide a partial strengthening effect, but when the Fe content exceeds 0.35%, it will promote the increase of coarse β phase, which is in the shape of rods or strips, affecting the appearance quality after anodizing. When the Fe content is not higher than 0.35%, the coarse β phase containing Fe will be evenly distributed on the cross section, avoiding the β phase from being distributed in a string along the rolling direction under the general rolling process. Although the surface glossiness of the cross section is not high after anodizing, the color uniformity is very good, which can well avoid the stripe color difference.

[0096] Ti: Ti can refine the grains and make the structure uniform, but when the content exceeds 0.02%, TiB2 tends to aggregate and form slag inclusions in the melt; if the addition amount is insufficient, the grain refinement effect cannot be achieved.

[0097] Mn and Cr: Both Mn and Cr are beneficial to improving the strength of the material and have a certain grain refinement effect.

[0098] The thickness of the aluminum alloy strip mentioned in the present application is 1.0~4.0mm. Due to the good control of the uniformity of the grain size in the thickness direction and the aluminum-magnesium precipitation phase, a finished product with a yield strength ≥160Mpa can be obtained as needed. More preferably, the yield strength of the aluminum alloy strip is 160~360Mpa.

[0099] Compared with the prior art, the aluminum alloy strip mentioned in the present invention has a thickness of 1.0~4.0mm and a yield strength of ≥160Mpa. Compared with the traditional 5-series alloy products, the aluminum alloy strip of the present application shows good appearance quality when anodized on any section. When making all-in-one computers and large-size displays, the four frame parts can be obtained by forging, upsetting and CNC to obtain a thicker size than the strip, and there is no obvious color difference after anodization, so it can be realized that the thick plate can be replaced by a thinner aluminum plate strip, which helps to improve efficiency and reduce production costs. And due to the thinning of the product thickness, better heat dissipation can be achieved to extend the service life of electronic products.

[0100] The above describes the basic principles, main features and advantages of the present invention. However, the above is only a specific embodiment of the present invention, and the technical features of the present invention are not limited thereto. Any other implementation methods derived by any technician in the field without departing from the technical solution of the present invention should be included in the patent scope of the present invention.

[0101] In the description of the present invention, each embodiment focuses on the differences from other embodiments, and the same or similar parts between the embodiments can be referred to each other. For the device disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and the relevant parts can be referred to the method part description.

[0102] In the description of the present invention, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply that there is any such actual relationship or order between these entities or operations. In the description of the present invention, the meaning of "multiple" is two or more, unless otherwise clearly and specifically limited. Moreover, the term "includes", "comprising" or any other variant thereof is intended to cover non-exclusive inclusion, so that the process, method, article or equipment including a series of elements not only includes those elements, but also includes other elements not clearly listed, or also includes elements inherent to such process, method, article or equipment. In the absence of more restrictions, the elements limited by the sentence "comprising one..." do not exclude the existence of other identical elements in the process, method, article or equipment including the elements.

[0103] In the present invention, unless otherwise clearly specified and limited, when a first feature is “on” or “below” a second feature, it may be that the first and second features are in direct contact, or that the first and second features are in indirect contact through an intermediate medium. Moreover, when a first feature is “above”, “above” or “above” a second feature, it may be that the first feature is directly above or obliquely above the second feature, or it may simply mean that the first feature is higher in level than the second feature. When a first feature is “below”, “below” or “below” a second feature, it may be that the first feature is directly below or obliquely below the second feature, or it may simply mean that the first feature is lower in level than the second feature.

[0104] In the description of this specification, the description of the terms "one embodiment", "some embodiments", "embodiment", "example", "specific example" or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, unless they are contradictory.

[0105] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations of the present invention. A person skilled in the art may alter, modify, replace and modify the above embodiments within the scope of the present invention.

Claims

1. A method for preparing anodized aluminum alloy strip for appearance, characterized in that: include: Step 1: melt the raw aluminum and the intermediate metal, analyze the composition of the melt, treat the melt quality, and then use semi-continuous casting to obtain an ingot; Step 2: sawing and milling the ingot and then soaking it, and then taking the ingot out of the furnace and hot rolling it to obtain a coil; Step 3: cold rolling the hot rolled coil for 1 to 7 passes to obtain a rolled material of a preset thickness, wherein the contact arc length L of the rolling deformation zone in each pass and the absolute deformation △H satisfy L≤10×△H; Step 4: The cold-rolled material to a preset thickness is subjected to a bending and straightening process to obtain a finished product; The raw aluminum includes: scrap aluminum or aluminum ingots; In step 2, the hot rolling includes: hot rough rolling, during which the absolute deformation of a single hot rolling pass before the ingot passes through the hot rough rolling outlet and reaches a thickness of ≥120 mm is no less than 40 mm; In step 2, the hot rolling process further includes: hot finishing rolling, during which the deformation of the ingot after hot rough rolling in a single pass of hot finishing rolling is not less than 40%; Taking the sum of weight percentage as 100%, the composition and content of the aluminum alloy strip are: Si≤0.06%, Fe≤0.35%, Cu≤0.1%, Cr≤0.35%, Ti≤0.02%, Mn content is 0.10~0.50%, Mg content is 2.0~3.5%, and the balance is Al and various non-negligible impurities.

2. The method for preparing an anodized aluminum alloy strip for appearance according to claim 1, characterized in that: In step 2, the process conditions for equalization are to control the temperature at 480-520°C for 8-20 hours.

3. The method for preparing an anodized aluminum alloy strip for appearance according to claim 1, characterized in that: In step 2, the final rolling temperature of the hot rolling is 320-360° C., and the thickness of the obtained coil is 2.0-5.0 mm.

4. The method for preparing an anodized aluminum alloy strip for appearance according to claim 1, characterized in that: In step 3, the total deformation of the hot-rolled coil after cold rolling is controlled to be above 20%.

5. The method for preparing an anodized aluminum alloy strip for appearance according to claim 1, characterized in that: In step 4, the elongation parameter of the stretch straightening process is set to 0.3~0.8%.

6. An anodized aluminum alloy strip for appearance, made by the method for preparing an anodized aluminum alloy strip for appearance according to any one of claims 1 to 5, characterized in that: Taking the sum of weight percentage as 100%, the composition and content of the aluminum alloy strip are: Si≤0.06%, Fe≤0.35%, Cu≤0.1%, Cr≤0.35%, Ti≤0.02%, Mn content is 0.10~0.50%, Mg content is 2.0~3.5%, and the balance is Al and various non-negligible impurities.

7. The anodized aluminum alloy strip for appearance according to claim 6, characterized in that: Taking the sum of the weight percentages as 100%, the content of each impurity is ≤0.03%, and the total weight of the impurities does not exceed 0.15% of the total weight of the aluminum alloy strip.

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