Aluminum alloy sheet for can body and its manufacturing method

Abstract

The present invention discloses an aluminum alloy sheet for can body and a manufacturing method thereof. The ratio of the main alloy elements Mn, Mg, Fe, and Si is optimized, and the distribution of intermetallic compounds is precisely controlled, thereby effectively reducing the occurrence rate of holes. The product has a utilization rate of recycled materials of the same series of 50% or more, a porosity area rate of 2 μm or more in the low magnification cross section of the ingot before homogenization is 0.05-0.18%, and a unique genetic structural characteristic of the absence of a large second phase of 70 μm or more in size. The AlFeMnSi phase conversion rate after homogenization is 80-95%. In the longitudinal section of the finished aluminum alloy sheet for can body, the total area ratio of intermetallic compound phases such as AlFeMnSi and inclusions of 5 μm or more is in the range of 0.08%-0.80%.

Description

[Technical field]

[0001] The present invention relates to the technical field of metal materials and their processing, and in particular to an aluminum alloy sheet for can bodies which is excellent in puncture resistance and low cost, and a method for producing the same. [Background technology]

[0002] Compared with tin-plated steel cans, aluminum cans have the advantages of light weight, corrosion resistance, good thermal conductivity, excellent processing formability, easy recycling, simple post-printing processing, and environmental friendliness, making them one of the most commonly used materials in the metal packaging industry. Aluminum alloy sheets for can bodies can be produced by homogenizing, hot rolling, and cold rolling large aluminum alloy flat ingots. After the produced alloy sheets are degreased, washed, and oiled, they can be used to produce beer can bodies and beverage can bodies through processes such as cup body forming, washing, drying, painting, baking, necking, and flanging.

[0003] Beer can bodies and beverage can bodies need a certain pressure resistance, but the strength of the can body will decrease after baking. In order to reduce the strength loss after baking, it is necessary to optimize and control the solid solution amount, relative content and precipitation amount of alloying elements, including impurity elements. If not properly controlled, substrates with high risk of holes will flow into downstream can-making companies. Because downstream companies have difficulty in traceability after can-making, they often isolate or return substrates with hole defects in bulk as a precaution, and the billing amount includes not only the can body itself but also the value of the entire can and the user's experience, which often exceeds the cost price of the can body several times, resulting in huge losses and waste of resources. Therefore, if recycled aluminum materials can be applied, it will bring great benefits to the ecological environment and energy utilization in the long term.

[0004] At present, the recovery, recycling technology and comprehensive utilization of aluminum can waste are attracting more attention from the product development industry. However, waste recycling involves more impurity elements such as Fe and Si, which imposes more severe tests on the utilization rate and quality control of existing recycled materials. However, the level of precise control of alloying elements, including impurity elements, directly affects the application scope of low-cost materials, so in order to continuously increase the proportion of recycled materials used, improving the ability to precisely control the type and relative content, size distribution and spatial distribution of intermetallic compounds in aluminum alloys is an inevitable major challenge in designing low-cost and high-performance deformed aluminum alloy packaging materials.

[0005] Among the existing aluminum alloy sheets for can bodies, there is no material that has a relatively low cost, a high recycled aluminum utilization rate, and a low pitting rate. Therefore, it is an urgent task for the wrought aluminum alloy product development industry to create a new environmentally friendly aluminum alloy that combines low cost and a low pitting rate. Summary of the Invention

[0006] In order to solve the above problems, the inventors conducted a usage simulation test on the composition components and impurity distribution of an aluminum material, and found that the type and spatial size distribution feature of intermetallic compounds in a matrix are closely related to the incidence rate of pitting defects in a can body material.

[0007] Based on this, one of the objects of the present application is to provide an aluminum alloy sheet for can bodies manufactured by using the same series of recycled can body material, the aluminum alloy sheet for can bodies containing, in mass%, 0.70-1.35% Mn, 0.80-1.55% Mg, 0.30-0.50% Si, 0.40-0.80% Fe (e.g., 0.40-0.75%), 0.15-0.35% Cu, 0-0.30% Zn, 0-0.08% Ti, 0.005-0.08% mixed rare earth Ce+La, and the balance being Al and other unavoidable impurities, with the proviso that the mass ratio of Fe / Si is greater than 1.5, and the amount of the same series of recycled can body material added accounts for 50% or more of the total weight of the aluminum alloy sheet. Preferably, the aluminum alloy sheet for can bodies contains, in mass%, 1.00-1.15% Mn, 0.80-1.20% Mg, 0.40-0.50% Si, 0.70-0.80% Fe, 0.20-0.30% Cu, 0.08-0.15% Zn, 0.05-0.08% Ti, mixed rare earths (RE, Rare Earth) Ce+La: 0.005-0.008%, and the remainder is Al and other unavoidable impurities, with the proviso that the mass ratio of Fe / Si is greater than 1.5 and equal to or less than 1.8.

[0008] In this specification, "the same series" refers to aluminum alloys having the same first digit in the GB / T 3190-2020 standard number (for example, 2219 and 2195, 7001 and 7075 each belong to the "same series of aluminum alloys").

[0009] In some prior art, to solve the problem of insufficient strength of can bodies manufactured from high-Si waste, the Fe / Si mass ratio is controlled to 1 or less, but this solution cannot solve the pitting defect. In this application, considering that the Si and Fe elements in the aluminum alloy recycled material have a negative effect on the microstructure and product performance, the Fe / Si mass ratio is limited to 1.5 or more when designing the chemical composition of the aluminum alloy plate for can bodies provided in this application, and the relative content of Mg is appropriately increased to overcome the negative effects of Si and Fe on the microstructure and product performance.

[0010] In this technical solution, trace amounts of rare earth elements (Ce and / or La) are added to take away oxygen from the high melting point, high hardness metal oxide inclusions SiO2, MnO2, FeO, and Al2O3 remaining in the melt, thereby plastically modifying the oxides and increasing the amount of solid solution of the main alloying elements. If the AlTi3 phase formed by Ti and Al elements is not well controlled, a relatively coarse second phase is likely to form. After adding recycled materials (waste materials such as aluminum cans), there is still excess Ti element in the original waste material, which is likely to precipitate with Al element and form a coarse second phase of AlTi3 after melting and casting. At this point, the content of Ti element in the matrix is ​​also likely to be high if the AlTiB modifier, which refines the grains, is added. Considering that rare earth elements are likely to form RE-B compounds with B elements, which become nucleation points to inhibit the growth of grains and have the effect of refining grains, the relative content of Al-Ti-B, which is a refiner, can be appropriately reduced.

[0011] In addition, with the added amount of recycled can body materials from this series accounting for more than 50% of the total metal mass, the input of primary aluminum will be significantly reduced, contributing to the cost-effective, low-carbon production of aluminum alloy materials for can bodies.

[0012] Furthermore, the total area ratio of intermetallic compound phases such as AlFeMnSi and inclusions having a size of 5 μm or more in the aluminum alloy sheet for can bodies is in the range of 0.08% to 0.80%, preferably 0.5% or less, for example, 0.2 to 0.5%, and / or the total area ratio of intermetallic compound phases and inclusions having a size of 0.5 to 5 μm is 0.3% to 1.5%, preferably 1.10% to 1.35%.

[0013] The edges of the intermetallic compounds are sharp and the plastic gap with the matrix is ​​large, so that the accumulation of dislocations is induced in the process of can body forming, and potential crack points are easily formed. At the same time, there are opposing forces between the intermetallic compounds, which may form voids or even form crack points inside the plate. Therefore, the occurrence rate of pitting in the can body cannot be reduced by only controlling the proportion of small-sized intermetallic compound phases. In the prior art, the cracking problem of the can body with high Si content is solved by limiting the area content of small-sized intermetallic compound phases. The present application reduces the occurrence of stress concentration and solves the cracking problem of low-cost aluminum alloy thin plate by controlling the area ratio of different-sized intermetallic compound phases and inclusions.

[0014] Furthermore, 75-95% of Fe, Si, and Mn elements in the aluminum alloy sheet for can body are converted to AlFeMnSi. Preferably, the AlFeMnSi phase conversion rate (area ratio) of the aluminum alloy sheet for can body is 80-95%, preferably 85-95%. The element conversion rate can be obtained by scanning a metal structure sample of the aluminum alloy sheet using an EPMA (Electron Probe X-ray Micro-Analyzer) and counting the total area of ​​pixel points corresponding to element signals.

[0015] Since the solid solubility of Fe in Al is only 0.002% at room temperature and 0.005% at 500°C, excess Fe and Al will generate the cathodic phase FeAl3, resulting in reduced local corrosion resistance. Furthermore, Fe and the solid solution strengthening alloying element Mn are prone to form coarse, flaky (FeMn)Al6 compounds, which on the one hand consume the amount of solid solution strengthening element Mn, causing softening during baking. On the other hand, the size distribution of intermetallic compounds is not properly controlled, increasing the risk of holes and cracks occurring in the thin can wall due to the internal pressure of the can. Excessive Si, together with Mn, will form the complex ternary phase Al 12Since it forms Mn3Si2, forms Mg2Si precipitates with Mg, and forms Al(FeMn)Si quaternary phase with Fe, promotes the conversion of the primary crystalline compound to the αAlFeMnSi phase, and the corrosion potential relationship is Mg2Si>Al6Mn>αAlFeMnSi>α-Al, increasing the relative proportion of αAlFeMnSi is beneficial to improving the corrosion resistance of can body materials, and the proportion of the αAlFeMnSi phase also has a non-negligible positive effect on the control of cube texture in the subsequent rolling process.

[0016] Furthermore, the size of the second phase (including non-Al matrix phases such as intermetallic compounds, simple phases, impurity phases, inclusions, etc.) in the aluminum alloy sheet for can bodies is 70 μm or less. By controlling the size of the second phase, the occurrence rate of pitting defects in the aluminum alloy sheet for can bodies can be effectively reduced.

[0017] Preferably, the aluminum alloy sheet for a can body has a porosity of 0.15% or less. Furthermore, the thickness of the aluminum alloy plate for the can body is 0.23 to 0.50 mm.

[0018] Further, the aluminum alloy sheet for can bodies has a tensile strength of 290 MPa or more, for example, 290 to 310 MPa, a yield strength of 270 MPa or more, for example, 270 to 290 MPa, and an elongation of 6.0% or more, for example, 6.0 to 7.0%.

[0019] Furthermore, the pre-service yield strength of the aluminum alloy sheet for can bodies is 250 MPa or more, for example, 250 to 260 MPa.

[0020] Furthermore, the rate of occurrence of holes in the aluminum alloy sheet for can bodies is 10 ppm or less, for example, 5 ppm or less.

[0021] Furthermore, the perforated fracture portion of the aluminum alloy sheet for can bodies is free of impurities. The main alloy composition of the aluminum alloy sheet for can body provided in this application is limited, and the α-AlFeMnSi phase conversion rate is quantitatively controlled, so that the distribution of the second phase is more dispersed and uniform, and the size distribution of the hazard class is further narrowed. The occurrence rate of pitting defects after can forming is reduced by 10 ppm or more compared to conventional processed products, showing excellent pitting resistance.

[0022] Another object of the present application is to The same series of recycled can body materials, aluminum ingots, rare earth metals, and metal additives are added and blended, and the added mass of the same series of recycled can body materials accounts for 50% or more, for example, 50 to 70% or 50 to 60%, of the total mass of the material, and the following mass % are contained in the material: Mn: 0.70 to 1.35%, Mg: 0.80 to 1.55%, Si: 0.30 to 0.50%, Fe: 0.40 to 0.80% (for example, 0.40 to 0.75%), Cu: 0.15 to 0.35%, Zn: 0 to 0.30%, The raw material composition is controlled to be Ti: 0-0.08%, mixed rare earths Ce+La: 0.005-0.008%, and the balance is Al and other unavoidable impurities, with the mass ratio of Fe / Si being greater than 1.5, and preferably controlled to be Mn: 1.00-1.15%, Mg: 0.80-1.20%, Si: 0.40-0.50%, Fe: 0.70-0.80%, Cu: 0.20-0.30%, Zn: 0.08-0.15%, Ti: 0.05-0.08%, mixed rare earths (RE, Rare Earth) Ce+La: 0.005-0.008%, and the balance is Al and other unavoidable impurities, with the mass ratio of Fe / Si being greater than 1.5 and 1.8 or less. Smelting and Casting to obtain a flat ingot; Homogenization, and The present invention provides a method for producing an aluminum alloy sheet for a can body, the method including a step of rolling.

[0023] This technical solution makes the distribution of matrix structure, impurity elements and inclusions in the aluminum alloy plate produced from recycled can body materials more uniform, and reduces the incidence of pitting defects in the aluminum alloy plate. At the same time, this technical solution reduces the input of primary aluminum, contributing to the cost-effective, low-carbon production of aluminum alloy materials for can bodies.

[0024] Furthermore, in the raw material blending step, an aluminum ingot with Al≧99.70% by mass is selected.

[0025] Furthermore, the recycled can body material is a 3-type aluminum alloy recycled material. The recycled material is also called recycled material or secondary material. It is an aluminum alloy or aluminum metal obtained by smelting waste aluminum, waste aluminum alloy material, or waste containing aluminum. The recycled material must undergo strict internal control testing before use. The 3-type aluminum alloy recycled material used in this application has the meaning well known in the art and refers to an aluminum alloy mainly composed of AlMn, derived from processed waste of AlMn aluminum alloys, recovered can materials, etc.

[0026] Furthermore, in the raw material blending step, metal additives are added in the following order depending on the melting points and burn-off rates of the alloy elements: Mn, Si, Fe, Cu, Mg, and mixed rare earths, thereby achieving further energy savings.

[0027] In addition, in the smelting step, a melting furnace is used for smelting, a holding furnace is used for refining, and then the mixture is left to stand. In some embodiments, AL-5Ti-0.2B is used as a refiner to perform online grain refinement, the input amount per ton of aluminum is 1.0-1.3 kg, online degassing is performed using a SNIF degasser (Spinning Nozzle Inert Floatation) to control the H content of the melt to 0.12 ml / 100 g Al or less, and the melt is purified by 50 PPI plate filtration and RC grade or higher tube filtration.

[0028] Furthermore, the flat ingot produced in the casting step has a porosity area rate of 2 μm or more in a low magnification cross section of 0.05 to 0.18%.

[0029] In some embodiments, to obtain a flat ingot, semi-continuous casting of the flat ingot is performed at a casting speed of 50-60 mm / min and a casting temperature of 660-710°C. The gate and dummy bar head portions of the flat ingot are then sawed and milled so that the sawing length of the ingot gate is 150 mm or more and the sawing length of the ingot dummy bar head is 400 mm. The produced flat ingot has a porosity area ratio of 0.05-0.18% with a diameter of 2 μm or more in a low magnification cross section. In some embodiments, before the homogenization treatment, the large surface of the flat ingot is milled with a milling amount of 10-15 mm, and the side surface of the ingot is milled with a milling amount of 8-12 mm.

[0030] Further, in the homogenization step, the flat ingot produced in the casting step is milled, and then homogenized at 570-610 ° C. for 8-15 hours, for example, 10-15 hours or 8-12 hours. The use of recycled materials introduces a relatively large amount of Si and Fe, which causes the coarse second phase to form a stress concentration point during forming, which is one of the main causes of hole defects, other than inclusions. In addition to all the advantages brought by the element ratio, this technical solution can optimize the segregation degree of elements in the ingot, not only avoiding overburning, but also ensuring an alpha phase conversion rate of more than 80%, and the distribution of matrix structure, impurity elements and inclusions is more uniform, so that the occurrence rate of hole defects after can forming can be reduced by more than 10 ppm compared with conventional processed products. Thereafter, the flat ingot is quenched to lower the temperature of the flat ingot to 510-540°C at full power, and is kept at that temperature for 2-12 hours before being poured and rolled, with the cooling rate controlled within 20-80°C / h.

[0031] Further, the rolling step includes: After milling the flat ingot, the flat ingot is quenched, and the initial temperature of the hot rough rolling is controlled to 510-540 ° C., and the final rolling temperature of the hot rough rolling is controlled to 450 ° C. or higher to obtain a hot rough rolled plate with a thickness of 30-45 mm. Hot finish rolling is performed on the hot rough rolled sheet, and the final rolling temperature of the hot finish rolling is controlled to 320 to 360 ° C. to obtain a hot finish rolled sheet having a thickness of 1.6 to 3.0 mm, preferably 1.6 to 2.5 mm. The final rolling temperature of the cold rolling is controlled to 145 to 160° C., and the rolling reduction of the final pass is controlled to 87% or more, thereby obtaining a cold rolled sheet having a thickness of 0.23 to 0.50 mm.

[0032] In some embodiments, in the rough hot rolling step, a rough hot rolled sheet having a thickness of 30 to 45 mm is obtained through 19 to 27 passes.

[0033] In some embodiments, in the cold rolling step, the total rolling reduction obtained through 3 to 5 passes is 87% or more.

[0034] In the prior art, if the reduction rate setting of the pass is not suitable for the material, the intermetallic compounds are likely to aggregate and grow into coarse harmful phases, leading to insufficient crushing, and the Mn alloying element around the coarse phases is consumed, making it impossible to reduce the risk of cracks. By adopting the above technical solution, on the one hand, the size of the second phase of the aluminum alloy plate for can body is 70 μm or less, so that the occurrence rate of hole defects in the aluminum alloy can body thin plate can be reduced, and on the other hand, thinner plates can be produced. [Brief description of the drawings]

[0035] [Figure 1] EPMA elemental mapping of the α-AlFeMnSi phase in Example 2 is shown, and the phase conversion rate is 91%. [Diagram 2] EPMA elemental mapping of the α-AlFeMnSi phase in Comparative Example 3 shows that the phase conversion rate is only 65%. [Figure 3a]1 shows a metallographic scanning electron microscope (SEM) image of the matrix structure in Comparative Example 1. [Figure 3b] 1 shows a scanning electron microscope image of a fracture portion at a hole defect portion in Comparative Example 1. [Figure 3c] The Energy Dispersive Spectroscopy (EDS) results of the particles in the fracture section in Figure 3b are shown, and the coarse second phase is Mg2Si. [Figure 4a] 1 shows a scanning electron microscope image of a fractured portion in a crack before use in Comparative Example 2. [Figure 4b] FIG. 4B shows the results of energy dispersive spectroscopy of the particles at the break in FIG. 4a. [Figure 5a] 1 shows a scanning electron microscope image of a fractured portion in a crack before use in Comparative Example 2. [Figure 5b] The results of energy dispersive spectroscopy of the particles in the fracture section of Fig. 5a are shown, which indicate that the particles are spinel-based inclusions and cracks are present. [Figure 6] 1 shows a scanning electron microscope image of the matrix structure in Comparative Example 3, in which there are single coarse second phase fractured morphologies of particles larger than 10 microns and surrounding pores. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0036] Hereinafter, the embodiments of the present invention will be described based on certain specific examples. Those skilled in the art can easily understand other advantages and effects of the present invention based on the contents disclosed in this specification. Although the present invention will be described in conjunction with a preferred embodiment, this does not mean that the features of the present invention are limited to this embodiment. On the contrary, the purpose of describing the present invention in conjunction with the embodiment is to cover other options or modifications that may be expanded based on the claims of the present invention. In order to deeply understand the present invention, the following description includes many specific details. The present invention can also be practiced without using these details. Furthermore, some specific details will be omitted to avoid confusing or obscuring the focus of the present invention. It should be noted that the embodiments of the present invention and the features of the embodiments can be combined with each other, provided that no inconsistency occurs.

[0037] It should be noted herein that like symbols and letters refer to like items in the following attached drawings, and that once an item is defined in one attached drawing, it need not be further defined and described in subsequent attached drawings. Also, when a range of numerical values ​​is referred to herein, unless otherwise stated, the range is intended to include its endpoints, and all integers and fractions within the range.

[0038] In order to make the objectives, technical solutions and advantages of the present invention clearer, the following describes the embodiments of the present invention in more detail with reference to the accompanying drawings.

[0039] The aluminum alloy sheet for can body provided in the present application can be produced by the following method. (1) Raw material composition The same series of recycled can body materials, aluminum ingots, rare earth metals, and metal additives are added and blended, and the added mass of the same series of recycled can body materials accounts for 50% or more of the total mass of the material, and is controlled so that, in mass%, Mn: 0.70-1.35%, Mg: 0.80-1.55%, Si: 0.30-0.50%, Fe: 0.40-0.80%, Cu: 0.15-0.35%, Zn: 0-0.30%, Ti: 0-0.08%, and mixed rare earth Ce+La: 0.005-0.008%, and the remainder is Fe and unavoidable impurities, and the mass ratio of Fe / Si is greater than 1.5.

[0040] In some embodiments, the can body recycling material is a Type 3 aluminum alloy recycling material, and an aluminum ingot with Al≧99.70% by mass is selected, and metal additives are added in the following order according to the melting points and burn-off ratios of the alloy elements: Mn, Si, Fe, Cu, Mg, and mixed rare earths, in that order, to further reduce energy consumption. (2) Smelting: A melting furnace is used for smelting, and a holding furnace is used for refining, and the metal is left to stand.

[0041] Then, in some embodiments, online grain refinement is performed using AL-5Ti-0.2B as a refiner, with a dosage of 1.0-1.3 kg per ton of aluminum, online degassing is performed using a SNIF (Spinning Nozzel Inert Floatation) degasser to control the H content of the melt to 0.12 ml / 100 g AL or less, and the melt is purified by 50 PPI plate filtration and RC grade or higher tube filtration. (3) Casting In some embodiments, to obtain a flat ingot, semi-continuous casting of the flat ingot is performed at a casting speed of 50-60 mm / min and a casting temperature of 660-710° C. The gate and dummy bar head portions of the flat ingot are then sawn and milled so that the sawing length of the ingot gate is 150 mm or more and the sawing length of the ingot dummy bar head is 400 mm. The produced flat ingot has a porosity area ratio of 0.05-0.18% for porosity of 2 μm or more in a low magnification cross section.

[0042] Prior to the homogenization process, the large surface of the flat ingot is milled with a milling amount of 10-15 mm, and the side of the ingot is milled with a milling amount of 8-12 mm. (4) Homogenization Homogenization is carried out at 570 to 610° C. and held for 8 to 15 hours, for example, 10 to 15 hours.

[0043] Thereafter, the flat ingot is quenched to lower the temperature of the flat ingot to 510-540°C at full power, and is kept at that temperature for 2-12 hours before being poured and rolled, with the cooling rate controlled within 20-80°C / h. (5) Rolling Hot rough rolling: The initial temperature of hot rough rolling is controlled to 510 to 540°C, for example, 530 to 540°C, and the final rolling temperature of hot rough rolling is controlled to 450°C or higher. After 19 to 27 passes, a hot rough rolled plate having a thickness of 30 to 45 mm is obtained.

[0044] Hot finish rolling: The hot rough rolled sheet is subjected to hot finish rolling, and the final rolling temperature of the hot finish rolling is controlled to 320 to 360°C to obtain a hot finish rolled sheet with a thickness of 1.6 to 3.0 mm.

[0045] Cold rolling: The final rolling temperature of cold rolling is controlled to 145 to 160°C, and a cold rolled sheet having a total rolling reduction of 87% or more and a thickness of 0.23 to 0.50 mm is obtained through 3 to 5 passes.

[0046] Finally, after trimming and oiling, the aluminum alloy plate for the can body is cut out. Working Example According to the above method, the examples and comparative examples of the present application are as follows.

[0047] Table 1 shows the composition and process index of Examples 1-3 and Comparative Examples 1-3. The alloy composition was controlled in the melting and casting stage according to GB / T 3190-2008 Chemical composition of deformed aluminum and aluminum alloys, GB / T20975.1-31 Chemical analysis method of aluminum and aluminum alloys, and YST805-2012 Rare earth analysis method in aluminum and aluminum alloys. By comparison, it can be seen that the utilization rate of the recycled aluminum material in Examples 1-3 is 50% or more, while the utilization rate of the recycled aluminum material in Comparative Examples 1-3 is 35% or less in all cases, and compared to the Examples, the Fe / Si mass ratio in Comparative Examples 1-3 is less than 1.5, no rare earth elements (Ce+La) are added, and the Cu element content in Comparative Example 2 is also lower.

[0048] Table 2 shows the purity indexes of Examples 1 to 3 and Comparative Examples 1 to 3. Low-density bulk materials are non-destructively measured using industrial CT, and the total area ratio of intermetallic compounds and inclusions of different sizes is obtained by pixel value statistics. Similarly, an optical microscope or a scanning electron microscope can be used to detect multiple aluminum alloy plate samples (e.g., three sheets) at a magnification of 50 to 1000 times to measure the area ratio of intermetallic compounds and inclusions. Surface scan measurements of aluminum alloy plate samples are performed using EPMA, and the ratio of Fe, Si, and Mn elements converted to αAlFeMnSi is obtained by measuring the image area. EPMA surface scans are performed on the samples of Example 2 and Comparative Example 3, respectively, to detect the distribution state of Fe, Si, and Mn elements therein, and the results are shown in Figures 1 and 2. According to the pixel statistics, 91% of Fe, Si, and Mn elements are distributed in αAlFEMnSi particles in Example 2, whereas only about 73% are distributed in Comparative Example 3. That is, in Example 2, most of the Fe, Si, and Mn elements are present in the form of the αAlFEMnSi phase, which is advantageous for alloy performance, whereas in Comparative Example 3, a significant portion of the Fe and Si forms phases such as FeAl3 that are prone to inducing corrosion, or combines with the Mn element to form (FeMn)Al6 compounds that are prone to cause seizure softening, increasing the risk of perforation.

[0049] Table 3 shows a comparison of the mechanical properties and pre-use performance indexes of Examples 1-3 and Comparative Examples 1-3. The mechanical property test methods such as tensile strength, yield strength, and elongation of the alloys met the test requirements of GB / T 228.1. Perforation occurrence rate = (perforated cans in the same batch / formed cans in the same batch) x 100%, among which, the perforated cans were identified and sorted by a line pinhole detector on the can material forming line. In this technical field, a 10 ppm reduction in the occurrence rate of perforation defects indicates a significant improvement in the product perforation rate.

[0050] [Table 1]

[0051] [Table 2]

[0052] [Table 3]

[0053] As a result of the comparison, the material purity index of the aluminum alloy plate for can body provided in the present application is good, its porosity is reduced (<0.15%), inclusions with large size and high hardness are effectively controlled and modified, the conversion rate of the second phase species (αAlFeMnSi phase conversion rate) is further improved, and the size distribution of the hazard class is further narrowed. Under the same plate thickness, the incidence rate of hole defects after can forming is reduced by 10 ppm or more compared to conventional processed products. When scanning electron microscope analysis was performed on the metal structure sample of Comparative Example 1, multiple particles of 10 μm or more were present in the sample structure, as shown in FIG. 3a. When scanning electron microscope analysis was performed on the fracture position of the perforated sample of Comparative Example 1, the result was as shown in FIG. 3b, and particulate matter with a width of about 10 μm was observed at the fracture position. When energy dispersive spectroscopy was performed on the particles in the cross section, the result was as shown in FIG. 3c, and the particulate matter in the cross section was Mg2Si. A scanning electron microscope analysis was performed on the fractured portion of the crack before use of the sample of Comparative Example 2, and the results were as shown in FIG. 4a, showing particulate matter of 10 μm or more at the fracture position. The particulate matter was subjected to energy dispersive spectroscopy, and the results were as shown in FIG. 4b, showing that the particulate matter in the cross section was SiO2. A scanning electron microscope analysis was performed on other fractured positions of the fractured sample before use of Comparative Example 2, and the results were as shown in FIG. 5a, showing that fractured particles of 10 μm or more were also present in the cross section. The results of the energy dispersive spectroscopy were shown in FIG. 5b, showing that the mixture was Mg-Si-O elements, and was presumed to be spinel-based inclusions. It was suggested that the reinforcing phase particles were not finely dispersed and distributed in the structure of Comparative Example 2, which is detrimental to the performance of the aluminum alloy sheet. A scanning electron microscope analysis was performed on the metal structure sample of Comparative Example 3, and as shown in FIG. 6, it was found that multiple large particulate matter of 10 μm or more was present in the sample structure, and that pores and cracks existed between the particulate matter and the matrix, indicating that these particulate matter have an adverse effect on the mechanical properties of the aluminum alloy sheet.

[0054] While the risk of holes is lower and the structural properties are better, the input rate of the same series of recycled materials in Examples 1 to 3 is increased to more than 50%, resulting in a total cost savings of 350 to 420 yuan / ton compared with Comparative Examples 1 to 3.

[0055] Although the present invention has been illustrated and described with reference to several preferred embodiments of the present invention, those skilled in the art should understand that the above contents are combined with specific embodiments to further explain the present invention in detail, and the specific embodiments of the present invention cannot be assumed to be limited only to these descriptions. Those skilled in the art can make various changes in form and details, including making some simple inferences or substitutions, without departing from the spirit and scope of the present invention.

Claims

1. An aluminum alloy plate for a can body, comprising, in mass%, Mn: 0.70-1.35%, Mg: 0.80-1.55%, Si: 0.30-0.50%, Fe: 0.40-0.80%, Cu: 0.15-0.35%, Zn: 0-0.30%, Ti: 0-0.08%, mixed rare earths Ce+La: 0.005-0.008%, and the balance being Al and other unavoidable impurities, with the proviso that the mass ratio of Fe / Si is greater than 1.5, Preferably, the aluminum alloy plate for can bodies contains, in mass%, 1.00-1.15% Mn, 0.80-1.20% Mg, 0.40-0.50% Si, 0.70-0.80% Fe, 0.20-0.30% Cu, 0.08-0.15% Zn, 0.05-0.08% Ti, mixed rare earths (RE, Rare Earth) Ce+La: 0.005-0.008%, and the balance is Al and other unavoidable impurities, with the proviso that the mass ratio of Fe / Si is greater than 1.5 and equal to or less than 1.8, The aluminum alloy plate for can bodies is characterized in that the content of the same series of recycled can body materials in the aluminum alloy plate for can bodies accounts for 50% or more of the total weight of the aluminum alloy plate.

2. In the aluminum alloy sheet for can bodies, The total area ratio of intermetallic phases and inclusions with sizes of 5 μm or more is in the range of 0.08% to 0.80%, and / or 2. The aluminum alloy sheet for can bodies according to claim 1, wherein a total area ratio of intermetallic compound phases and inclusions having sizes of 0.5 to 5 μm is 0.3% to 1.5%.

3. In the aluminum alloy sheet for can bodies, The total area ratio of intermetallic phases and inclusions larger than 5 μm is 0.5% or less, and / or 2. The aluminum alloy sheet for can bodies according to claim 1, wherein a total area ratio of intermetallic compound phases and inclusions having a size of 0.5 to 5 μm is 1.10% to 1.35%.

4. The aluminum alloy sheet for can bodies according to claim 1, wherein 75-95%, preferably 80% or more of Fe, Si and Mn elements in the aluminum alloy sheet for can bodies are converted into AlFeMnSi phase.

5. The aluminum alloy plate for can body has a tensile strength of 290 MPa or more, for example, 290-310 MPa, a yield strength of 270 MPa or more, for example, 270-290 MPa, and an elongation of 6.0% or more, for example, 6.0-7.0%; and / or The pre-service yield strength of the aluminum alloy plate for can bodies is 250 MPa or more, for example, 250 to 260 MPa; and / or The aluminum alloy plate for can bodies has a pitting rate of 10 ppm or less, for example, 5 ppm or less, and / or 2. The aluminum alloy sheet for a can body according to claim 1, wherein the perforated fracture portion of the aluminum alloy sheet for a can body is free of impurities.

6. 2. The aluminum alloy sheet for a can body according to claim 1, wherein the porosity of the aluminum alloy sheet for a can body is 0.15% or less.

7. 2. The aluminum alloy sheet for a can body according to claim 1, wherein the size of the second phase of the aluminum alloy sheet for a can body is 70 μm or less.

8. 2. The aluminum alloy sheet for can bodies according to claim 1, wherein the aluminum alloy sheet for can bodies has a thickness of 0.23 to 0.50 mm.

9. A method for producing an aluminum alloy sheet for a can body, comprising the steps of: The same series of recycled can body materials, aluminum ingots, rare earth metals, and metal additives are added and blended, and the added mass of the same series of recycled can body materials accounts for 50% or more of the total mass of the material, and the mass percentages of the material are as follows: Mn: 0.70-1.35%, Mg: 0.80-1.55%, Si: 0.30-0.50%, Fe: 0.40-0.80%, Cu: 0.15-0.35%, Zn: 0-0.30%, Ti: 0-0.08%, mixed rare earth Ce+ The raw material composition is controlled to be La: 0.005-0.008%, the balance being Fe and unavoidable impurities, with the mass ratio of Fe / Si being greater than 1.5, preferably in mass%, and is controlled to be Mn: 1.00-1.15%, Mg: 0.80-1.20%, Si: 0.40-0.50%, Fe: 0.70-0.80%, Cu: 0.20-0.30%, Zn: 0.08-0.15%, Ti: 0.05-0.08%, mixed rare earth (RE, Rare Earth) Ce + La: 0.005-0.008%, and the balance being Al and other unavoidable impurities, with the mass ratio of Fe / Si being greater than 1.5 and 1.8 or less. Smelting and Casting to obtain a flat ingot; Homogenization, and A method for producing an aluminum alloy sheet for a can body, comprising the step of rolling.

10. The can body recycled material is a 3-type aluminum alloy recycled material, and / or 10. The method for producing an aluminum alloy sheet for a can body according to claim 9, wherein the aluminum ingot has an Al content of 99.70 wt% or more.

11. 10. The method for producing an aluminum alloy sheet for a can body according to claim 9, wherein in the raw material blending step, the metal additives are added in the order of Mn, Si, Fe, Cu, Mg, and mixed rare earths.

12. A melting furnace is used for smelting, a holding furnace is used for refining, and then the mixture is left to stand. The method for producing aluminum alloy sheet for can body according to claim 9, characterized in that online grain refinement is preferably performed using Al-5Ti-0.2B as a refiner, the input amount per ton of aluminum is 1.0-1.3 kg, online degassing is performed using a SNIF degasser to control the H content of the melt to be below 0.12 ml / 100 g Al, and the melt is purified by 50 PPI plate filtration and RC grade or above tube filtration.

13. The flat ingot produced in the casting step has a porosity area ratio of 2 μm or more in a low magnification cross section of 0.05 to 0.18%, The method for producing an aluminum alloy sheet for a can body according to claim 9, characterized in that, preferably, to obtain a flat ingot, semi-continuous casting of the flat ingot is carried out at a casting speed of 50-60 mm / min and a casting temperature of 660-710°C, and then sawing and milling gate and dummy bar head parts of the flat ingot, so that the sawing length of the ingot gate is not less than 150 mm, and the sawing length of the ingot dummy bar head is not less than 400 mm.

14. In the homogenization step, the flat ingot produced in the casting step is milled, and then homogenized at 570 to 610 ° C. and held for 8 to 15 hours; Preferably, the large surface of the flat ingot is milled with a milling amount of 10 to 15 mm, and the side surface of the flat ingot is milled with a milling amount of 8 to 12 mm; The method for producing an aluminum alloy sheet for a can body according to claim 9, characterized in that, after the homogenization treatment, the flat ingot is cooled at a temperature decreasing rate of 20 to 80°C / h to reduce the temperature of the flat ingot to 510 to 540°C, and then kept at that temperature for 2 to 12 hours before tapping.

15. The rolling step includes: After milling the flat ingot, the flat ingot is quenched, and the initial temperature of the hot rough rolling is controlled to 510 to 540 ° C., and the final rolling temperature of the hot rough rolling is controlled to 450 ° C. or higher to obtain a hot rough rolled plate having a thickness of 30 to 45 mm, preferably through 19 to 27 passes to obtain a hot rough rolled plate having a thickness of 30 to 45 mm; Hot finish rolling is performed on the hot rough rolled sheet, and the final rolling temperature of the hot finish rolling is controlled to 320 to 360 ° C. to obtain a hot finish rolled sheet having a thickness of 1.6 to 3.0 mm. The method for producing an aluminum alloy sheet for a can body according to claim 9, characterized in that a final rolling temperature of the cold rolling is controlled to 145 to 160°C, and a total reduction ratio of the final pass is controlled to 87% or more to obtain a cold rolled sheet having a thickness of 0.23 to 0.50 mm, preferably, a total reduction ratio obtained through 3 to 5 passes is 87% or more.

Images