Aluminum alloy plate and preparation method thereof

Abstract

The invention provides an aluminum alloy plate and a preparation method thereof. The aluminum alloy plate comprises the following elements in percentage by mass: 0.90-1.50 wt% of Si element, 0.20-0.50 wt% of Fe element, less than or equal to 0.15 wt% of Cu element, 0.20-0.40 wt% of Mn element, 0.30-0.50 wt% of Mg element, less than or equal to 0.15 wt% of total content of inevitable impurities, less than or equal to 0.05 wt% of single impurity and the balance of Al element, the sum of the content of Mn element and the content of Fe element is 0.40-0.80 wt%, and the balance is Al element. The content ratio of the Mn element to the Fe element is (0.78-1.30): 1. The aluminum alloy plate has high surface quality and mechanical property under the condition of high iron content.

Description

Technical Field

[0001] The present invention relates to the technical field of aluminum alloys, and in particular to an aluminum alloy plate and a preparation method thereof. Background Art

[0002] At present, the world's automobile industry is developing rapidly, the number of cars in use is increasing year by year, and energy consumption and environmental pollution are increasing day by day, bringing severe tests to nature. In order to promote the sustainable development of the automobile industry and take into account the purpose of energy saving and consumption reduction and environmental protection, the proportion of aluminum alloys used in new energy vehicles is increasing. Aluminum alloys can reduce the weight of the car, improve fuel efficiency, reduce environmental pollution pressure, and have good recycling performance. However, the Fe content of recycled aluminum is relatively high, which will produce a second phase that is unfavorable to the mechanical properties and forming properties of the material, restricting the application of recycled aluminum in automobile covering parts, especially Al-Mg-Si outer covering parts.

[0003] At present, the research on Al-Mg-Si for car body outer covering parts involves improving the flanging, formability and surface quality of the material. It is mainly used in outer covering parts, and the production process is also diverse. The Chinese patent application with patent application publication number CN109868398A discloses a 6xxx series aluminum alloy sheet with high flanging performance and its preparation method. The flanging performance of the covering parts for automobile outer panels is improved by regulating the distribution of the second phase and the grain size, but intermediate annealing is required, the production process is complicated and the cost is high. The Chinese patent application with patent application publication number CN115354179A discloses 6xxx aluminum alloy sheet, its preparation method and application. The organization and texture are optimized by regulating the hot rolling pass and the reduction amount, and the surface paint brush line is improved. The subsequent production process of this method also requires intermediate annealing, and the control of the second phase is not explained, and the production process is complicated. The Chinese patent application with the patent application publication number CN111440970A discloses a 6-series aluminum alloy sheet for automobile body outer panel and its preparation method. By strictly controlling the hot rolling process and performing two intermediate annealings in cold rolling, a material with high surface quality is obtained. The cost of the two intermediate annealings is high, and the Fe content range of 0.10-0.20% is controlled narrowly, which is not conducive to the use of production process waste and recycled aluminum ingots. The Chinese patent application with the patent application publication number CN114921697A discloses a 6xxx series aluminum alloy sheet for engine cover inner panel, its preparation method and application. By inventing a new composition range alloy, controlling the atomic ratio of Mg and Si, performing low solution temperature treatment at 460-530°C, and pre-aging in a holding furnace, a material with low yield strength and high elongation is obtained, but the strength is low and can only be used in the inner panel field. Summary of the invention

[0004] The main purpose of the present invention is to provide an aluminum alloy plate and a preparation method thereof, so as to solve the problem of high production cost of aluminum alloy plates in the prior art.

[0005] In order to achieve the above-mentioned purpose, according to one aspect of the present invention, there is provided an aluminum alloy plate material, which comprises the following elements, measured in mass percentage: Si element content is 0.90-1.50wt%, Fe element content is 0.20-0.50wt%, Cu element content is ≤0.15wt%, Mn element content is 0.20-0.40wt%, Mg element content is 0.30-0.50wt%, the total content of inevitable impurities is ≤0.15wt%, the content of a single impurity does not exceed 0.05wt%, the balance is Al element, the sum of the contents of Mn element and Fe element is 0.40-0.80wt%, and the content ratio of Mn element to Fe element is 0.78-1.30:1.

[0006] Furthermore, the above-mentioned aluminum alloy plate includes the following elements: the content of Si element is 1.00-1.10wt%, the content of Fe element is 0.25-0.45wt%, the content of Cu element is 0.04-0.10wt%, the content of Mn element is 0.25-0.35wt%, the content of Mg element is 0.35-0.45wt%, the total content of inevitable impurities is ≤0.15wt%, the content of a single impurity does not exceed 0.05wt%, and the balance is Al element; and / or, the sum of the contents of Mn element and Fe element is 0.50-0.80wt%; and / or, the ratio of the content of Mn element to Fe element is 1.00-1.30:1.

[0007] Furthermore, the grain size of the above-mentioned aluminum alloy plate does not exceed 25μm; and / or the equivalent circle diameter of the second phase in the aluminum alloy plate does not exceed 3.0μm; and / or the volume fraction of the second phase in the aluminum alloy plate is 1.0-2.0%; and / or the volume fraction of Goss texture in the aluminum alloy plate is less than 3%; and / or the volume fraction of Cube texture in the aluminum alloy plate is less than 4%; and / or the paint brush line grade of the aluminum alloy plate reaches level 2 or above.

[0008] According to another aspect of the present invention, there is provided a method for preparing the aforementioned aluminum alloy plate, the method comprising: step S1, melting and casting various raw materials including metals in accordance with a proportion in sequence to obtain an aluminum alloy ingot; step S2, subjecting the aluminum alloy ingot to a homogenization treatment, a hot rolling treatment, a cold rolling treatment, a solution treatment, and a pre-aging treatment in sequence to obtain an aluminum alloy plate.

[0009] Furthermore, in the above step S1, the mass proportion of the waste in the raw material is 40-60%, and the waste includes the following elements in mass percentage: the content of Si element is 0.40-1.00wt%, the content of Fe element is ≤0.35wt%, the content of Cu element is ≤0.12wt%, the content of Mn element is ≤0.40wt%, the content of Mg element is 0.25-0.60wt%, and the balance is aluminum; and / or the thickness of the aluminum alloy ingot is 500-700mm.

[0010] Furthermore, in the above step S2, the heating rate of the homogenization treatment is 30-40°C / h; and / or, the temperature of the homogenization treatment is 540-570°C; and / or, the holding time of the homogenization treatment is 6-16h.

[0011] Furthermore, in the above step S2, the starting temperature of the hot rolling treatment is 540-555°C; and / or the thickness of the aluminum material after the hot rolling treatment is 2.0-4.0 mm; and / or the finishing temperature of the hot rolling treatment is 320-360°C.

[0012] Furthermore, in the above step S2, the thickness of the aluminum material after cold rolling is 0.9-1.2 mm.

[0013] Furthermore, in the above step S2, the temperature of the solution treatment is 540-560°C; and / or the holding time of the solution treatment is 30-120s; preferably, the temperature of the solution treatment is 550-555°C; and / or the holding time of the solution treatment is 30-60s.

[0014] Furthermore, in the above step S2, the temperature of the pre-aging treatment is 70-90°C; preferably, the temperature of the pre-aging treatment is T, and when 70°C≤T<80°C, the insulation time of the pre-aging treatment is not less than 4h; or; when 80°C≤T≤90°C, no insulation is performed; preferably, when 70°C≤T<80°C, the insulation time of the pre-aging treatment is 4-8h.

[0015] By applying the technical solution of the present invention, the upper limit of the Fe element in the aluminum alloy sheet of the present application reaches 0.50wt%, with a high Fe content. The raw materials prepared by the aluminum alloy sheet can use more recycled aluminum ingots or process waste, which is helpful to promote the recycling of waste materials, reduce the use of original aluminum ingots, and be more green, low-carbon, and environmentally friendly, and the cost of the aluminum alloy sheet is lower. Usually, excessive Fe elements tend to form a coarse second phase in the alloy, thereby affecting the strength and toughness of the material. The present application controls the content of Mn elements, especially controls the sum of the content of Mn elements and Fe elements to 0.40-0.80wt%, and the content ratio of Mn elements to Fe elements to 0.78-1.30:1, which helps to promote the uniform precipitation of second phases such as Al(FeMn) and Al(FeMn)Si, and helps to solve the problem of insufficient mechanical properties and forming properties of aluminum alloy sheets due to uneven enrichment of Fe elements. Therefore, the aluminum alloy plate of the present application has higher surface quality and mechanical properties with a higher iron content, and the aluminum alloy plate can be applied to the field of automobile covering parts, especially body outer covering parts, to help reduce the material cost of automobile production. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The drawings constituting a part of the present application are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0017] Figure 1 An optical photograph showing the paint brush line grade of the present application is one level;

[0018] Figure 2 An optical photograph showing the paint brush line grade of the present application is level 2;

[0019] Figure 3 An optical photograph showing the paint brush line grade of the present application is level three;

[0020] Figure 4 An optical photograph showing the paint brush line grade of the present application is four levels. DETAILED DESCRIPTION

[0021] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0022] Terminology explanation: PSN mechanism refers to particle stimulated nucleation mechanism.

[0023] As analyzed in the background technology of this application, there is a problem of high production cost of aluminum alloy plates in the prior art. In order to solve the above problem, this application provides an aluminum alloy plate and a preparation method thereof.

[0024] In a typical embodiment of the present application, an aluminum alloy plate is provided, which includes the following elements, measured in mass percentage: the content of Si element is 0.90-1.50wt%, the content of Fe element is 0.20-0.50wt%, the content of Cu element is ≤0.15wt%, the content of Mn element is 0.20-0.40wt%, the content of Mg element is 0.30-0.50wt%, the total content of unavoidable impurities is ≤0.15wt%, the content of a single impurity does not exceed 0.05wt%, the balance is Al element, the sum of the contents of Mn element and Fe element is 0.40-0.80wt%, and the content ratio of Mn element to Fe element is 0.78-1.30:1.

[0025] The upper limit of the Fe element in the aluminum alloy sheet of the present application reaches 0.50wt%, with a high Fe content. More recycled aluminum ingots or process waste can be used in the raw materials prepared therefrom, which helps to promote the recycling of waste materials, reduce the use of original aluminum ingots, is more green, low-carbon, and environmentally friendly, and the cost of the aluminum alloy sheet is lower. Usually, excessive Fe elements are easy to form a coarse second phase in the alloy, thereby affecting the strength and toughness of the material. The present application controls the content of the Mn element, especially controls the sum of the content of the Mn element and the Fe element to be 0.40-0.80wt%, and the content ratio of the Mn element to the Fe element is 0.78-1.30:1, which helps to promote the uniform precipitation of the second phase such as Al(FeMn) and Al(FeMn)Si, and helps to solve the problem of insufficient mechanical properties and forming properties of the aluminum alloy sheet due to uneven enrichment of the Fe element. Therefore, the aluminum alloy sheet of the present application has higher surface quality and mechanical properties when it has a higher iron content. The aluminum alloy sheet can be applied to the field of automobile covering parts, especially the outer covering parts of the body, which helps to reduce the material cost of automobile production.

[0026] In order to further improve the surface quality and mechanical properties of the aluminum alloy plate, in one embodiment of the present application, the aluminum alloy plate preferably includes the following elements: the content of Si element is 1.00-1.10wt%, the content of Fe element is 0.25-0.45wt%, the content of Cu element is 0.04-0.10wt%, the content of Mn element is 0.25-0.35wt%, the content of Mg element is 0.35-0.45wt%, the total content of unavoidable impurities is ≤0.15wt%, the content of a single impurity does not exceed 0.05wt%, and the balance is Al element; and / or, the sum of the contents of Mn element and Fe element is 0.50-0.80wt%; and / or, the ratio of the content of Mn element to Fe element is 1.00-1.30:1.

[0027] In one embodiment of the present application, the grain size of the above-mentioned aluminum alloy plate does not exceed 25μm; and / or the equivalent circle diameter of the second phase in the aluminum alloy plate does not exceed 3.0μm; and / or the volume fraction of the second phase in the aluminum alloy plate is 1.0-2.0%; and / or the volume fraction of Goss texture in the aluminum alloy plate is less than 3%; and / or the volume fraction of Cube texture in the aluminum alloy plate is less than 4%; and / or the paint brush line grade of the aluminum alloy plate reaches level 2 or above.

[0028] Aluminum alloy sheets having the above-mentioned grain size, second phase equivalent circle diameter, second phase volume fraction, Cube texture volume fraction ratio, and Goss texture volume fraction ratio range have higher mechanical properties and surface quality. Therefore, the paint brush line of the aluminum alloy sheet of the present application reaches level 2 or above and can be applied to vehicle body exterior covering parts.

[0029] In another typical embodiment of the present application, a method for preparing the aforementioned aluminum alloy plate is provided, and the preparation method comprises: step S1, melting and casting various raw materials including metals in accordance with a proportion in sequence to obtain an aluminum alloy ingot; step S2, subjecting the aluminum alloy ingot to a homogenization treatment, a hot rolling treatment, a cold rolling treatment, a solution treatment, and a pre-aging treatment in sequence to obtain an aluminum alloy plate.

[0030] In this application, the aluminum alloy ingot is subjected to homogenization treatment, hot rolling treatment, cold rolling treatment, solution treatment, and pre-aging treatment in sequence, which helps to regulate the grain size, second phase size and distribution, texture type and proportion inside the aluminum alloy plate, thereby helping to improve the paint line performance and mechanical properties of the aluminum alloy plate. In addition, this application adopts a short-process process to eliminate the intermediate annealing process for producing the outer cover material, greatly shortening the production cycle, helping to improve production efficiency, reduce energy consumption, and reduce production costs.

[0031] In one embodiment of the present application, the preparation method further comprises cutting and milling the cast aluminum part obtained by casting to obtain an aluminum alloy ingot.

[0032] In one embodiment of the present application, in the above-mentioned step S1, the mass proportion of the waste in the raw material is 40-60%, and the waste includes the following elements in mass percentage: the content of Si element is 0.40-1.00wt%, the content of Fe element is ≤0.35wt%, the content of Cu element is ≤0.12wt%, the content of Mn element is ≤0.40wt%, the content of Mg element is 0.25-0.60wt%, and the balance is aluminum; and / or the thickness of the aluminum alloy ingot is 500-700mm.

[0033] The mass proportion of waste in the raw materials is within the above range, which helps to promote the recycling of waste and reduce the use of original aluminum ingots, thereby helping to reduce the production cost of aluminum alloy plates. It is preferred to control the thickness of the aluminum alloy ingot within the above range, which is conducive to the penetration and uniform distribution of heat in the subsequent homogenization treatment, and helps to uniformly dissolve the elements inside the material and reasonably distribute the second phase, thereby helping to improve the efficiency and effect of heat treatment.

[0034] In one embodiment of the present application, in the above step S2, the heating rate of the homogenization treatment is 30-40°C / h; and / or, the temperature of the homogenization treatment is 540-570°C; and / or, the holding time of the homogenization treatment is 6-16h.

[0035] It is preferred to control the heating rate of the homogenization treatment within the above range, which helps to improve the uniform heating of the material and the stability of the internal structure, thereby facilitating subsequent processing. It is preferred to control the temperature of the homogenization treatment within the above range, which helps to control the precipitation of the second phase (Al(FeMn), Al(FeMn)Si, etc.), refine the grains using the PSN mechanism, and reduce unfavorable textures, thereby helping to improve the paint brush line performance of the material. It is preferred to control the holding time of the homogenization treatment within the above range, which helps to improve the efficiency of the homogenization treatment while eliminating composition segregation and microstructural inhomogeneity, thereby helping to improve the consistency of the internal organization of the material.

[0036] In one embodiment of the present application, in the above step S2, the starting temperature of the hot rolling treatment is 540-555°C; and / or the thickness of the aluminum material after the hot rolling treatment is 2.0-4.0 mm; and / or the finishing temperature of the hot rolling treatment is 320-360°C.

[0037] It is preferred to control the start rolling temperature of the hot rolling treatment within the above range, which helps to soften the material in the initial stage of hot rolling, promote the sufficient and uniform crushing of the insoluble second phases such as Al(FeMn) and Al(FeMn)Si, and obtain a large number of submicron second phase particles, creating conditions for the PSN mechanism to function. It also helps to improve the plasticity of the material, reduce the risk of cracks and fractures during hot rolling, and help improve the processing stability and efficiency of the material under large deformation rates. The appropriate thickness after hot rolling provides favorable conditions for the cold rolling process, which is beneficial for the precise control of the thickness of the plate and the improvement of the surface quality during the cold rolling process. It is preferred to control the final rolling temperature of the hot rolling treatment within the above range, which helps to improve the stability of the internal grain structure of the material, promote the precipitation of the second phase particles in a suitable state, and provide a good microstructural foundation for subsequent solid solution and pre-aging treatments.

[0038] In one embodiment of the present application, when the temperature of the homogenization treatment is the same as the starting temperature of the hot rolling treatment, the aluminum material that has completed the homogenization treatment and is kept warm is directly subjected to the hot rolling treatment; when the temperature of the homogenization treatment is different from the starting temperature of the hot rolling treatment, the aluminum material that has completed the homogenization treatment and is kept warm at the starting temperature for 1 hour before rolling.

[0039] In one embodiment of the present application, in the above step S2, the thickness of the aluminum material after cold rolling is 0.9-1.2 mm.

[0040] It is preferred to control the thickness of the aluminum material after cold rolling within the above range, which is helpful to further optimize the microstructure of the plate, including the refinement of grains and the control of the size of the second phase. During the solution and pre-aging treatment process, the plate in this thickness range is conducive to the PSN mechanism of the second phase particles, that is, through the uniform distribution of submicron second phase particles, the grain size is refined, which helps to reduce the content of Goss texture and Cube texture, and further helps to improve the paint brush line performance of the aluminum alloy plate.

[0041] In one embodiment of the present application, in the above-mentioned step S2, the temperature of the solution treatment is 540-560°C; and / or the holding time of the solution treatment is 30-120s; preferably, the temperature of the solution treatment is 550-555°C; and / or the holding time of the solution treatment is 30-60s.

[0042] It is preferred to control the temperature of the solution treatment within the above range, which helps to promote the dissolution of the second (such as Al(FeMn), Al(FeMn)Si, etc.), improve the solid solubility, and help to refine the grain size, reduce the Goss texture and Cube texture content of the material, reduce the grain orientation consistency of the material, and help disrupt the trend of alternating distribution of soft and hard textures, thereby helping to improve the mechanical properties and surface quality of the aluminum alloy plate.

[0043] In one embodiment of the present application, the above-mentioned solution treatment is carried out in a continuous annealing line air cushion furnace.

[0044] In one embodiment of the present application, in the above step S2, the temperature of the pre-aging treatment is 70-90°C; preferably, the temperature of the pre-aging treatment is T, when 70°C≤T<80°C, the insulation time of the pre-aging treatment is not less than 4h; or; when 80°C≤T≤90°C, no insulation is performed; preferably, when 70°C≤T<80°C, the insulation time of the pre-aging treatment is 4-8h.

[0045] It is preferred to control the conditions of the pre-aging treatment within the above range, which helps to promote the stable precipitation of fine second phase particles, further refine the grains through the PSN mechanism, and reduce the proportion of Goss texture and Cube texture, thereby helping to improve the surface quality and mechanical properties of the aluminum alloy plate.

[0046] The beneficial effects of the present application will be further illustrated below in conjunction with embodiments.

[0047] Examples 1 to 8, Comparative Examples 1 to 3

[0048] Step 1, in terms of mass percentage, pure aluminum, master alloy, process waste, etc. are melted and cast according to the composition and proportion of Table 1, the process waste includes the following elements: Si element content is 1.00wt%, Fe element content is 0.35wt%, Cu element content is 0.12wt%, Mn element content is 0.40wt%, Mg element content is 0.60wt%, the thickness of the obtained aluminum alloy ingot is 630mm, the aluminum alloy ingot is cut and milled, and the thickness of the aluminum alloy ingot after milling is 600mm;

[0049] Step 2, the aluminum alloy ingot is subjected to homogenization treatment, the temperature is raised to the soaking temperature at 35°C / h, and the temperature is kept for 8h. The soaking temperature of each test example is respectively implemented according to Table 2;

[0050] Step 3, the ingot after soaking is directly taken out of the furnace for rolling or cooled to the rolling temperature and kept at this temperature for 1 hour before directly rolling, hot rolling to the final rolling thickness, and then cooled at room temperature. The actual values ​​of the rolling temperature, final rolling temperature, and final rolling thickness of each test example are shown in Table 2;

[0051] Step 4, cold rolling the cooled hot-rolled coil to a finished product with a thickness of 1.0 mm;

[0052] Step 5, transfer the cold-rolled coil to the continuous annealing line air cushion furnace for solution treatment, the solution temperature is 560°C, the holding time is 30s, and then air-cooled to room temperature; pre-aging treatment is performed, the actual value of the coiling temperature is shown in Table 2, the holding time of the pre-aging treatment is 4h, and after holding, it is cooled to room temperature to obtain an aluminum alloy plate.

[0053] Table 1

[0054]

[0055] Table 2

[0056]

[0057] Example 9

[0058] The difference from Example 4 is that the heating rate of the homogenization treatment is 30° C. / h, the temperature of the homogenization treatment is 540° C., the holding time of the homogenization treatment is 16 h, and finally an aluminum alloy plate is obtained.

[0059] Example 10

[0060] The difference from Example 4 is that the heating rate of the homogenization treatment is 40° C. / h, the temperature of the homogenization treatment is 570° C., the holding time of the homogenization treatment is 6 h, and finally an aluminum alloy plate is obtained.

[0061] Embodiment 11

[0062] The difference from Example 4 is that the heating rate of the homogenization treatment is 45° C. / h, the temperature of the homogenization treatment is 580° C., the holding time of the homogenization treatment is 5 h, and finally an aluminum alloy plate is obtained.

[0063] Example 12

[0064] The difference from Example 4 is that the starting rolling temperature of the hot rolling treatment is 540° C., the thickness of the aluminum material after the hot rolling treatment is 2.5 mm, and an aluminum alloy plate is finally obtained.

[0065] Example 13

[0066] The difference from Example 4 is that the starting rolling temperature of the hot rolling treatment is 570° C., the thickness of the aluminum material after the hot rolling treatment is 4.0 mm, and an aluminum alloy plate is finally obtained.

[0067] Embodiment 14

[0068] The difference from Example 4 is that the hot rolling final rolling temperature is 360° C., and an aluminum alloy sheet is finally obtained.

[0069] Embodiment 15

[0070] The difference from Example 4 is that the hot rolling final rolling temperature is 320° C., and an aluminum alloy sheet is finally obtained.

[0071] Example 16

[0072] The difference from Example 4 is that the hot rolling final rolling temperature is 310° C., and an aluminum alloy sheet is finally obtained.

[0073] Embodiment 17

[0074] The difference from Example 4 is that the temperature of the solution treatment is 545° C., the holding time of the solution treatment is 120 s, and finally an aluminum alloy plate is obtained.

[0075] Embodiment 18

[0076] The difference from Example 4 is that the temperature of the solution treatment is 570° C., the holding time of the solution treatment is 20 s, and finally an aluminum alloy plate is obtained.

[0077] Embodiment 19

[0078] The difference from Example 4 is that the pre-aging treatment temperature is 60° C., the pre-aging treatment holding time is 3 h, and finally an aluminum alloy plate is obtained.

[0079] Performance Testing

[0080] The aluminum alloy plates prepared in the above embodiments and comparative examples were measured for grain size, second phase equivalent circle diameter, second phase volume fraction, Goss volume fraction, Cube volume fraction and paint brush line grade. The measurement results are shown in Table 3.

[0081] Grain size measurement method: Use a metallographic microscope to take pictures of the grains in the longitudinal section of the material, calculate the number of intercept points where the test line segment of known length intersects the grain interface, and calculate the average grain diameter.

[0082] Equivalent circular diameter of the second phase: Use a scanning electron microscope to take a picture of the second phase in the longitudinal section of the material, count the number and area of ​​the second phase within a known area, and calculate the average area size of the second phase; assuming that the second phase is circular, the equivalent circular diameter of the second phase can be calculated using the average area of ​​the second phase.

[0083] Volume fraction of the second phase: Use a scanning electron microscope to take a picture of the second phase in the longitudinal section of the material, count the area of ​​the second phase within a known area, and divide the area of ​​the second phase by the known area to obtain the volume fraction of the second phase.

[0084] Goss and Cube texture measurement: Use electron backscatter diffraction to measure and analyze crystal orientation, with self-Goss orientation {011} <100> Grains with orientations within 11° offset have a self-Cube orientation {001} <100> Grains with orientations within 11° deviation.

[0085] Paint brush wire performance test: a strip sample with a length of 250mm and a width of 35mm is cut from the finished plate. The length direction of the sample is perpendicular to the rolling direction, and the width direction is parallel to the rolling direction. After the sample is pre-stretched by 10% along the length direction, it is polished with a 320-mesh oilstone. The surface morphology of the polished sample is graded and evaluated. The paint brush wire grade is divided into grade one, grade two, grade three and grade four according to the national standard GB / T33227. The effect of grade one is as follows: Figure 1 As shown: There is no obvious paint line along the width direction, and the secondary effect is as follows Figure 2 As shown: there are intermittent paint lines along the width direction, and no penetrating paint lines. The effect of the third level is as follows Figure 3 As shown: There are sparse paint brush lines running through the width direction. The effect of the fourth level is as follows Figure 4 As shown: dense penetrating paint lines appear along the width direction. Level 1 and 2 are acceptable, while levels 3 and 4 are unacceptable.

[0086] The aluminum alloy plates prepared in the above examples and comparative examples were subjected to room temperature tensile mechanical property tests according to the national standard GB / T33227, including tensile strength Rm , specify the non-proportional extension strength R p0.2 , Elongation after fracture A 50 , Total elongation at maximum force A g , strain hardening exponent n 10-20 , plastic strain ratio r 10 ; and baking hardening performance test, that is, the tensile strength R after the material is subjected to 2% pre-stretching deformation and simulated baking at 185℃ for 20 minutes m , specify the non-proportional extension strength R p0.2 , Elongation after fracture A 50 , the results are shown in Table 4.

[0087] Table 3

[0088]

[0089] Table 4

[0090]

[0091]

[0092] From the above description, it can be seen that the above embodiments of the present invention achieve the following technical effects:

[0093] The upper limit of the Fe element in the aluminum alloy sheet of the present application reaches 0.50wt%, with a high Fe content. More recycled aluminum ingots or process waste can be used in the raw materials prepared therefrom, which helps to promote the recycling of waste materials, reduce the use of original aluminum ingots, is more green, low-carbon, and environmentally friendly, and the cost of the aluminum alloy sheet is lower. Usually, excessive Fe elements are easy to form a coarse second phase in the alloy, thereby affecting the strength and toughness of the material. The present application controls the content of the Mn element, especially controls the sum of the content of the Mn element and the Fe element to be 0.40-0.80wt%, and the content ratio of the Mn element to the Fe element is 0.78-1.30:1, which helps to promote the uniform precipitation of the second phase such as Al(FeMn) and Al(FeMn)Si, and helps to solve the problem of insufficient mechanical properties and forming properties of the aluminum alloy sheet due to uneven enrichment of the Fe element. Therefore, the aluminum alloy sheet of the present application has higher surface quality and mechanical properties when it has a higher iron content. The aluminum alloy sheet can be applied to the field of automobile covering parts, especially the outer covering parts of the body, which helps to reduce the material cost of automobile production.

[0094] The above are only embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. An aluminum alloy plate, characterized in that: In terms of mass percentage, the aluminum alloy plate includes the following elements: the content of Si element is 0.90-1.50wt%, the content of Fe element is 0.20-0.50wt%, the content of Cu element is ≤0.15wt%, the content of Mn element is 0.20-0.40wt%, the content of Mg element is 0.30-0.50wt%, the total content of inevitable impurities is ≤0.15wt%, the content of a single impurity does not exceed 0.05wt%, the balance is Al element, and the sum of the content of Mn element and the content of Fe element is 0.40-0.80wt%, and the content ratio of Mn element to Fe element is 0.78-1.30:

1.

2. The aluminum alloy sheet according to claim 1, characterized in that: The aluminum alloy plate comprises the following elements: the Si content is 1.00-1.10wt%, the Fe content is 0.25-0.45wt%, the Cu content is 0.04-0.10wt%, the Mn content is 0.25-0.35wt%, the Mg content is 0.35-0.45wt%, the total content of inevitable impurities is ≤0.15wt%, the content of a single impurity does not exceed 0.05wt%, and the balance is the Al element; and / or the sum of the contents of the Mn element and the Fe element is 0.50-0.80wt%; and / or the ratio of the content of the Mn element to the Fe element is 1.00-1.30:

1.

3. The aluminum alloy sheet according to claim 1 or 2, characterized in that: The grain size of the aluminum alloy plate does not exceed 25 μm; and / or the equivalent circle diameter of the second phase in the aluminum alloy plate does not exceed 3.0 μm; and / or the volume fraction of the second phase in the aluminum alloy plate is 1.0-2.0%; and / or the volume fraction of the Goss texture in the aluminum alloy plate is less than 3%; and / or the volume fraction of the Cube texture in the aluminum alloy plate is less than 4%; and / or the paint brush line grade of the aluminum alloy plate reaches level 2 or above.

4. A method for preparing the aluminum alloy sheet according to any one of claims 1 to 3, characterized in that: The preparation method comprises: Step S1, melting and casting various raw materials including metals in accordance with the proportions in sequence to obtain an aluminum alloy ingot; Step S2, subjecting the aluminum alloy ingot to homogenization treatment, hot rolling treatment, cold rolling treatment, solution treatment, and pre-aging treatment in sequence to obtain the aluminum alloy plate.

5. The preparation method according to claim 4, characterized in that: In the step S1, the mass proportion of the waste in the raw material is 40-60%, and the waste includes the following elements in mass percentage: the content of Si element is 0.40-1.00wt%, the content of Fe element is ≤0.35wt%, the content of Cu element is ≤0.12wt%, the content of Mn element is ≤0.40wt%, the content of Mg element is 0.25-0.60wt%, and the balance is aluminum; and / or the thickness of the aluminum alloy ingot is 500-700mm.

6. The preparation method according to claim 4 or 5, characterized in that: In the step S2, the heating rate of the homogenization treatment is 30-40°C / h; and / or, the temperature of the homogenization treatment is 540-570°C; and / or, the holding time of the homogenization treatment is 6-16h.

7. The preparation method according to any one of claims 4 to 6, characterized in that: In the step S2, the starting temperature of the hot rolling process is 540-555°C; and / or the thickness of the aluminum material after the hot rolling process is 2.0-4.0 mm; and / or the finishing temperature of the hot rolling process is 320-360°C.

8. The preparation method according to any one of claims 4 to 7, characterized in that In the step S2, the thickness of the aluminum material after the cold rolling treatment is 0.9-1.2 mm.

9. The preparation method according to any one of claims 4 to 8, characterized in that: In step S2, the temperature of the solution treatment is 540-560° C.; and / or the holding time of the solution treatment is 30-120 s; Preferably, the temperature of the solution treatment is 550-555° C.; and / or the holding time of the solution treatment is 30-60 s.

10. The preparation method according to any one of claims 4 to 9, characterized in that: In the step S2, the temperature of the pre-aging treatment is 70-90°C; preferably, the temperature of the pre-aging treatment is T, and when 70°C≤T<80°C, the holding time of the pre-aging treatment is not less than 4h; Or; when 80℃≤T≤90℃, no heat preservation is performed; Preferably, when 70°C ≤ T < 80°C, the holding time of the pre-aging treatment is 4 to 8 hours.

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