Aluminum alloy plate for pull ring

Abstract

One aspect of the present disclosure provides an aluminum alloy plate for a tab in which the content of silicon (Si) is 0.10 mass% or more and 0.60 mass% or less, the content of iron (Fe) is 0.20 mass% or more and 0.70 mass% or less, the content of copper (Cu) is 0.10 mass% or more and 0.40 mass% or less, the content of manganese (Mn) is 0.5 mass% or more and 1.2 mass% or less, and the content of magnesium (Mg) is 1.1 mass% or more and 4.0 mass% or less. The remainder comprises aluminum (Al) and unavoidable impurities, or comprises aluminum and unavoidable impurities, and the sheet thickness t (mm) and the tensile strength [sigma] B0 DEG (MPa) in a direction of 0 DEG with respect to the rolling direction satisfy the following mathematical formula (1). (2.7 * t-0. 45) * sigma B0 degree > = 67 (1).

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This international application claims the priority of Japanese Patent Application No. 2023-067404 filed in the Japan Patent Office on April 17, 2023, the entire contents of which are incorporated herein by reference. Technical Field

[0003] The present disclosure relates to an aluminum alloy plate for a pull ring. Background Art

[0004] In recent years, with the increasing awareness of environmental protection, aluminum alloy plates with less carbon dioxide emissions during the manufacturing process are required. The amount of new aluminum matrix metal mixed in the casting process has a significant indirect impact on carbon dioxide emissions in the aluminum manufacturing process.

[0005] The production of new aluminum matrix metal consumes a lot of electricity in the refining process, resulting in a large amount of carbon dioxide emissions. Therefore, reducing the mixing amount of new aluminum matrix metal and increasing the same-grade recycling rate will help reduce carbon dioxide emissions in aluminum alloy sheet production.

[0006] Generally speaking, the amount of carbon dioxide emitted when aluminum scrap is remelted and cast can be reduced to about one-thirtieth of that when new aluminum matrix metal is produced. In particular, the production of aluminum alloy sheets for beverage cans used worldwide is extremely large, and further improving the same-grade recycling rate is of great significance to reducing the environmental burden.

[0007] Among them, compared with the can body made of 3104 aluminum alloy (AA3104 alloy), the upper limit of the component specifications of silicon (Si), iron (Fe), copper (Cu), manganese (Mn), etc. in the can cover mainly made of 5182 aluminum alloy (AA5182 alloy) is lower, so it is difficult to mix the waste derived from the can material containing 3104 aluminum alloy.

[0008] For example, if the can waste (UBC: Used Beverage Can) generated on the market is mixed as it is, according to the weight ratio of the can body and the can cover, it will contain more 3104 aluminum alloy components, so it is easy to exceed the upper limit of the composition of 5182 aluminum alloy, and it is necessary to use new base metal to dilute the composition.

[0009] Therefore, compared with the aluminum alloy sheet for the can body, the aluminum alloy sheet for the pull ring needs to use more new base metal to adjust the composition to the composition of the 5182 aluminum alloy, resulting in a lower recycling rate. Therefore, by changing the pull ring to an alloy whose composition is easily mixed with the 3104 aluminum alloy, the use rate of new base metal in the pull ring can be significantly reduced.

[0010] Patent Documents 1 to 4 disclose aluminum alloy sheets for pull rings having improved formability or opening properties.

[0011] Prior art documents

[0012] Patent documents

[0013] Patent document 1: Japanese Patent Laid-Open No. 5-263175

[0014] Patent document 2: Japanese Patent Laid-Open No. 2017-066458

[0015] Patent document 3: Japanese Patent Laid-Open No. 2017-166052

[0016] Patent document 4: Japanese Patent Laid-Open No. 2011-225977. Summary of the invention

[0017] Problems to be solved by the invention

[0018] When an aluminum alloy having a composition close to that of 3104 aluminum alloy is used as the alloy for the pull tab, problems such as a decrease in the bending strength of the pull tab and a decrease in the toughness of the material occur. The bending strength of the pull tab is an index indicating the difficulty of bending the pull tab pulled up when opening the can.

[0019] Generally, the greater the plate thickness and the greater the strength of the material, the greater the bending strength of the pull tab. Therefore, 5182 aluminum alloy with high strength containing a large amount of magnesium (Mg) is used in the pull tab.

[0020] In this regard, if the conventional 3104 aluminum alloy is used for the pull tab, the bending strength of the pull tab is significantly reduced, and when opening the can, the pulled-up pull tab bends, increasing the risk of poor can opening. In addition, if the plate thickness is too thick to increase the bending strength of the pull tab, it will lead to an increase in the weight of the pull tab and an increase in the cost of the pull tab.

[0021] In addition, the toughness of the material affects the formability and openability of the pull tab. If the toughness of the material is low, forming cracks are particularly likely to occur in the bending processed portion of the pull tab. In addition, there is a risk of the root of the pull tab breaking when opening the can and a risk of the pull tab detaching when the pull tab is repeatedly pulled up.

[0022] However, the conventional aluminum alloy sheet for pull tabs with a recycling rate cannot solve the above two problems, that is, one or both of the bending strength and toughness (formability and openability) of the pull tab.

[0023] One aspect of the present disclosure preferably provides an aluminum alloy sheet for a pull tab that can mix waste raw materials derived from can materials and can simultaneously achieve high bending strength and high toughness of the pull tab.

[0024] Means for solving the problems

[0025] One embodiment of the present disclosure relates to an aluminum alloy sheet for a pull tab, wherein the content of silicon (Si) is 0.10% by mass or more and 0.60% by mass or less, the content of iron (Fe) is 0.20% by mass or more and 0.70% by mass or less, the content of copper (Cu) is 0.10% by mass or more and 0.40% by mass or less, the content of manganese (Mn) is 0.5% by mass or more and 1.2% by mass or less, and the content of magnesium (Mg) is 1.1% by mass or more and 4.0% by mass or less, and the balance is composed of aluminum (Al) and inevitable impurities, or contains aluminum and inevitable impurities. In addition, the plate thickness t (mm) and the tensile strength σ B_0° (MPa) in the direction of 0° relative to the rolling direction satisfy the following mathematical formula (1).

[0026] (2.7 × t - 0.45) × σ B_0° ≧67 (1)

[0027] According to the above configuration, it is possible to mix waste raw materials derived from can materials and at the same time achieve high pull tab bending strength and high toughness of the aluminum alloy sheet. That is, it is possible to mix waste of 3104 aluminum alloy for cans in an amount of a certain amount or more, thereby reducing the usage rate of new base metal and the carbon dioxide emission. In addition, an aluminum alloy sheet for a pull tab that achieves both formability and openability can be obtained. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 is an explanatory view of the L-ST cross section.

[0029] Figure 2A is a schematic perspective view of an Erichsen cup; Figure 2B is a schematic top view of the Erichsen cup.

[0030] Figure 3 is a diagram showing an example of the measurement result of the side wall height of the Erichsen cup.

[0031] Figure 4 is a diagram showing the relationship between the value V in the embodiment and the pull tab bending strength. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0032] Hereinafter, embodiments applying the present disclosure will be described with reference to the drawings.

[0033] [1. First Embodiment]

[0034] [1-1. Configuration]

[0035] <Components>

[0036] The aluminum alloy sheet for a pull tab (hereinafter also simply referred to as "alloy sheet") of the present disclosure contains aluminum (Al), silicon (Si), iron (Fe), copper (Cu), manganese (Mn), and magnesium (Mg).

[0037] The lower limit of the Si content is 0.10% by mass, preferably 0.20% by mass. If the Si content is less than 0.10% by mass, the amount of Si precipitated in the processing heat of cold rolling after hot rolling and solution treatment decreases, which may lead to insufficient tensile strength of the alloy plate.

[0038] In addition, the average value of the Si component specification of 3104 aluminum alloy specified in JIS-H-4000:2014 is 0.30% by mass, and the average value of the Si component specification of 5182 aluminum alloy specified in JIS-H-4000:2014 is 0.10% by mass. Therefore, by setting the Si content to 0.20% by mass or more, a large amount of 3104 aluminum alloy scrap can be mixed.

[0039] The upper limit of the Si content is 0.60% by mass, preferably 0.40% by mass. If the Si content exceeds 0.60% by mass, the Mg2Si particles increase, resulting in a decrease in the toughness of the alloy plate.

[0040] The lower limit of the Fe content is 0.20% by mass, preferably 0.30% by mass. The average value of the Fe component specification of 3104 aluminum alloy is 0.40% by mass, and the average value of the Fe component specification of 5182 aluminum alloy is 0.18% by mass. Therefore, by setting the Fe content to 0.20% by mass or more, a large amount of 3104 aluminum alloy scrap can be mixed.

[0041] The upper limit of the Fe content is 0.70% by mass. If the Fe content exceeds 0.70% by mass, the Al-Fe-Mn-based or Al-Fe-Mn-Si-based intermetallic compounds (i.e., the second-phase particles) increase. As a result, a crack propagation path is generated, leading to a decrease in the toughness of the alloy plate.

[0042] The lower limit of the Cu content is 0.10% by mass, preferably 0.11% by mass, more preferably 0.20% by mass. If the Cu content is less than 0.10% by mass, the Cu for increasing the tensile strength is insufficient due to solution or precipitation, resulting in a decrease in the tensile strength of the alloy plate. In addition, by precipitating Cu in the cold rolling process after hot rolling and solution treatment, the tensile strength of the alloy plate can be significantly improved.

[0043] In addition, the average value of the Cu component specification of 3104 aluminum alloy is 0.15% by mass, and the average value of the Cu component specification of 5182 aluminum alloy is 0.075% by mass. Therefore, by setting the Cu content to 0.11% by mass or more, a large amount of 3104 aluminum alloy scrap can be mixed.

[0044] The upper limit of the Cu content is 0.40% by mass. If the Cu content exceeds 0.40% by mass, the toughness of the alloy plate decreases.

[0045] The lower limit of the Mn content is 0.5% by mass, preferably 0.7% by mass, and more preferably 0.8% by mass. If the Mn content is less than 0.5% by mass, there is insufficient Mn to increase the tensile strength by solid solution or precipitation, resulting in a decrease in the tensile strength of the alloy plate.

[0046] In addition, the average value of the Mn composition specification of 3104 aluminum alloy is 1.1% by mass, and the average value of the Mn composition specification of 5182 aluminum alloy is 0.35% by mass. Therefore, by setting the Mn content to 0.7% by mass or more, a large amount of 3104 aluminum alloy scrap can be mixed.

[0047] The upper limit of the Mn content is 1.2% by mass, preferably 1.0% by mass. If the Mn content exceeds 1.2% by mass, the Al-Fe-Mn-based or Al-Fe-Mn-Si-based intermetallic compounds (i.e., the second-phase particles) increase. As a result, a crack propagation path is generated, leading to a decrease in the toughness of the alloy plate.

[0048] The lower limit of the Mg content is 1.1% by mass. If the Mg content is less than 1.1% by mass, there is insufficient Mg to increase the tensile strength by solid solution or precipitation, resulting in a decrease in the tensile strength of the alloy plate. In addition, by precipitating Mg during cold rolling after hot rolling and solution treatment, the tensile strength of the alloy plate can be significantly increased.

[0049] The upper limit of the Mg content is 4.0% by mass, preferably 3.0% by mass. The average value of the Mg composition specification of 3104 aluminum alloy is 1.05% by mass, and the average value of the Mg composition specification of 5182 aluminum alloy is 4.5% by mass. Therefore, by setting the Mg content to 4.0% by mass or less, more preferably 3.0% by mass or less, a large amount of 3104 aluminum alloy scrap can be mixed, and the additional mixing amount of the Mg-containing raw material can be reduced.

[0050] The alloy plate may contain titanium (Ti). The upper limit of the Ti content is preferably 0.10% by mass. By containing Ti, the ingot structure of the alloy plate is refined. If the Ti content exceeds 0.10% by mass, coarse crystals are generated during casting, resulting in a significant decrease in the toughness of the alloy plate.

[0051] In addition, the alloy plate may contain zinc (Zn). The upper limit of the Zn content is preferably 0.25% by mass. If the zinc content exceeds 0.25% by mass, the corrosion resistance of the alloy plate deteriorates.

[0052] In addition, the alloy plate may contain chromium (Cr). The upper limit of the content of Cr is preferably 0.10% by mass. If the content of Cr exceeds 0.10% by mass, coarse crystals are generated during casting, resulting in a significant reduction in the toughness of the alloy plate.

[0053] The alloy plate may contain inevitable impurities within a range that does not significantly impair the performance of the alloy plate. That is, the alloy plate contains Si, Fe, Cu, Mn, Mg, Ti, Zn, and Cr within the above ranges, and the balance is composed of aluminum and inevitable impurities, or contains aluminum and inevitable impurities. The upper limit of the total amount of inevitable impurities is preferably 0.15% by mass. The balance may contain substances other than aluminum and inevitable impurities.

[0054] <Plate thickness, material strength, and tab bending strength>

[0055] The plate thickness t (mm) of the aluminum alloy plate of the present disclosure and the tensile strength σ B_0° (MPa) in the direction of 0° with respect to the rolling direction satisfy the following mathematical formula (1).

[0056] V = (2.7 × t - 0.45) × σ B_0° ≧67 (1)

[0057] The tensile strength σ in the mathematical formula (1) B_0° is measured by the method specified in JIS-Z-2241:2011. For example, a micrometer is used to measure the plate thickness t.

[0058] According to experience, there is a strong positive correlation between the tab bending strength value of the tab made of aluminum alloy and the value V (i.e., the left side of the mathematical formula (1)). Therefore, by making the value V 67 or more, a tab having sufficient tab bending strength can be formed.

[0059] In addition, the tensile strength σ B_0° is preferably 330 MPa or more. Thus, a tab having a sufficient tab bending strength value can be formed without significantly increasing the plate thickness of the alloy plate.

[0060] The mechanical significance of the relationship between the value V and the tab bending strength can be explained as follows. That is, when pulling up the tab to open the can, if the resistance of the tab is lower than the load applied to the tab, plastic deformation starts due to local material yield before the score is normally opened. Tab bending is a phenomenon in which this plastic deformation continues to progress and the tab bends.

[0061] Considering the cross-section parallel to the bending ridge line at the position where tab bending occurs on the tab, the resistance to the bending moment applied to the cross-section due to pulling up the tab increases with the section modulus and the 0.2% yield strength σ 0.2increases with the increase of, where the section modulus is a value inherent to the cross-sectional shape, and the 0.2% yield strength σ 0.2 is the yield strength of the material.

[0062] If it is a pull tab with a fixed shape such as the common Stay On Tab shape of DRT company type, the higher the section modulus of the above cross-section is with the increase of the plate thickness. Therefore, it is possible to explain the degree of ease of starting to bend caused by the yield and plastic deformation of the material during the bending of the pull tab through the plate thickness and the 0.2% yield strength σ 0.2 of the material.

[0063] In addition, the bending of the pull tab is a phenomenon that includes the progress of plastic deformation until the pull tab is bent. Therefore, it is necessary to consider the work hardening of the material during plastic deformation. Even when the 0.2% yield strength σ 0.2 is low, so that plastic deformation starts earlier, if the amount of work hardening during plastic deformation is large, the progress of plastic deformation is suppressed, and thus the pull tab is not easily bent.

[0064] Therefore, the tensile strength σ B_0° is introduced to replace the 0.2% yield strength σ 0.2 as an index representing the strength of the material including work hardening. By using the value V represented by the plate thickness t and the tensile strength σ B_0° the bendability of the pull tab of the aluminum alloy plate can be evaluated.

[0065] For example, the bend strength of the pull tab of the aluminum alloy plate is measured through the following steps. Perform a conversion process other than notching on the shell formed by the aluminum alloy plate, thereby forming a can lid as an end without notches. Further, install the pull tab formed by the aluminum alloy plate on the can lid. Fix the can lid to a fixture and pull up the pull tab. At this time, take the value of the maximum load applied to the pulling part as the bend strength of the pull tab.

[0066] Specifically, for the forming of the pull tab, use a pull tab mold with the common Stay On Tab shape of DRT company type. For the forming of the shell, use, for example (B64)-shaped shell mold. For the measurement of the bend strength of the pull tab, for example, use the Pop / Tear Tester of LEAD Detector Co., Ltd.

[0067] More specifically, a lid of a can without notches and with a pull tab formed by a dedicated jig is fixed to the jig. Then, a jig for applying a load is installed on the pulling portion of the pull tab, and the jig for applying the load is fixed in a state where a load that does not cause plastic deformation of the pull tab is applied in a direction perpendicular to the plate portion of the lid body. In this state, the lid body is rotated at a rotational speed of 30° / second, thereby pulling up and bending the pull tab. Within the range up to a rotation angle of 90°, the maximum value of the load applied to the pulling portion of the pull tab is read.

[0068] <Toughness>

[0069] It is known that the toughness of an aluminum alloy plate affects the formability and openability of the pull tab.

[0070] (Number of repeated bends)

[0071] One of the evaluation indexes of the toughness of an aluminum alloy plate is the repeated bending test. If the plate thickness is the same, the more the number of repeated bends, the more excellent the toughness of the aluminum alloy plate.

[0072] The repeated bending test is carried out according to the following steps. For example, a strip-shaped specimen cut to a width of 12.5 mm and a length of 200 mm is arranged so that the direction of the bending ridge line is parallel to the rolling direction of the alloy plate. Both ends of the specimen are fixed with chucks, and a tensile force of 200 N is applied.

[0073] In this state, a jig with a bending radius R of 2.0 mm located at a position 150 mm from the end of the specimen fixed to the fixed chuck on one side along the longitudinal direction of the specimen is used as a fulcrum, and the chuck on the other side is rotated 90° to the left and right, and the bending is repeated, and the number of bends until the specimen breaks is measured.

[0074] The number of bends is counted as one operation for bending 90° to the left or right and returning to the initial position. If it breaks halfway, the angle θ (0° - 90°) is read, and the number of repeated bends N is calculated using the following mathematical formula (2). In mathematical formula (2), N0 is the total number of operations for bending 90° to the left or right and returning from the bent 90° position to the initial 0° position until the specimen breaks.

[0075] N = N0 + θ / 90 (2)

[0076] In the repeated bending evaluation, the larger the plate thickness, the more disadvantageous it is. Therefore, it is necessary to correct it using a reference plate thickness. Thus, with a plate thickness of 0.245 mm as the reference, the standardized number of repeated bends N is calculated by the following mathematical formula (3). s . In addition, t t (mm) is the plate thickness of the specimen.

[0077] N s= N × t t / 0.245 (3)

[0078] (Second-phase particles)

[0079] Toughness is affected by the tensile strength and the distribution of second-phase particles. That is, the greater the tensile strength and the higher the density of second-phase particles, the lower the toughness. In particular, if the contents of Mg and Si increase, Mg2Si particles are likely to form. As a result, Mg2Si particles become the starting points and propagation paths of cracks, leading to a reduction in toughness.

[0080] In the central region of the plate thickness of the L-ST cross section as shown by the oblique line in Figure 1 , the ratio of the total area of Mg2Si particles with an area of 0.3 μm 2 or more is preferably 1.0% or less. In addition, in Figure 1 , L is the longitudinal direction, ST is the plate thickness direction, and LT is the width direction.

[0081] For example, the area ratio of Mg2Si particles can be measured by the following method. First, cut the measurement sample, and mechanically polish the surface to be measured (i.e., the L-ST cross section) to a mirror finish. Next, observe the polished surface (i.e., the L-ST cross section) using SEM (scanning electron microscope), and obtain 10 fields of view in the central region of the plate thickness. Set the acceleration voltage of the SEM to 15 kV, the magnification to 500 times, and the range of one field of view to 0.049 mm 2 to take pictures, thereby obtaining a COMPO (reflected electron composition) image.

[0082] Analyze the taken COMPO image using the image analysis software "ImageJ". Specifically, set the brightness value that appears most frequently among the 256 gray levels in the image as the background brightness, and determine the particles with a brightness lower than the value obtained by subtracting 30 from the brightness value that appears most frequently as Mg2Si particles.

[0083] Among the determined Mg2Si particles, calculate the total area of particles with an area of 0.3 μm 2 or more, and divide it by the photographed area of 10 fields of view (i.e., the total photographed area), thereby calculating the ratio of the total area of Mg2Si particles with an area of 0.3 μm 2 or more in the L-ST cross section.

[0084] (Earing rate)

[0085] Texture also affects the number of repeated bends, and the higher the aggregation degree of the cube orientation, the better. The aggregation degree of the cube orientation is determined by Figure 2A and Figure 2BThe Erichsen test shown is represented by the ear shape of an Erichsen cup E formed from an aluminum alloy sheet.

[0086] Specifically, the greater the relative sidewall height H (i.e., the ear height) of the sidewall of the Erichsen cup E in the 0° / 180° direction with respect to the rolling direction RD of the aluminum alloy sheet compared to the sidewall height H in the 45° direction with respect to the rolling direction RD, the higher the degree of aggregation of the cube orientation. That is, the aluminum alloy sheet of the present disclosure includes an aluminum alloy sheet having a relatively large degree of aggregation of the cube orientation and a relatively high sidewall height H in the 0° / 180° direction.

[0087] The relative sidewall height of the sidewall height in the 0° / 180° direction with respect to the sidewall height in the 45° direction can be evaluated using an index called the earing balance. Hereinafter, the measurement steps of the earing balance will be described.

[0088] The earing balance is represented by the left side of the following mathematical formula (4).

[0089] (h 0p - h 45p ) / h v × 100 ≥ -7.0 (4)

[0090] In the mathematical formula (4), h 0p is the average value of the maximum values of the sidewall heights of the first region A1 near 0° and the second region A2 near 180° with respect to the rolling direction. The first region A1 is, for example, within the range of 0° ± 11° with respect to the rolling direction. The second region A2 is, for example, within the range of 180° ± 11° with respect to the rolling direction.

[0091] h 45p is the average value of the maximum values of the sidewall heights of the third region A3 near 45°, the fourth region A4 near 135°, the fifth region A5 near 225°, and the sixth region A6 near 315° with respect to the rolling direction.

[0092] The third region A3 is, for example, within the range of 45° ± 22° with respect to the rolling direction. The fourth region A4 is, for example, within the range of 135° ± 22° with respect to the rolling direction. The fifth region A5 is, for example, within the range of 225° ± 22° with respect to the rolling direction. The sixth region A6 is, for example, within the range of 315° ± 22° with respect to the rolling direction.

[0093] h vThe average of the minimum values of the sidewall heights of the seventh region A7 from 0° to 45°, the eighth region A8 from 45° to 135°, the ninth region A9 from 135° to 180°, the tenth region A10 from 180° to 225°, the eleventh region A11 from 225° to 315°, and the twelfth region A12 from 315° to 360° with respect to the rolling direction, respectively.

[0094] Figure 3 FIG. is an example showing the measurement results of the sidewall height of the Erichsen cup. Figure 3 The angles shown are angles with respect to the rolling direction. In addition, the distance from the center of the figure represents the sidewall height.

[0095] a - d in the figure are the maximum values in the third region A3 to the sixth region A6, respectively. e and f are the maximum values in the first region A1 and the second region A2, respectively. g - l are the minimum values in the seventh region A7 to the twelfth region A12, respectively.

[0096] For example, the Erichsen cup E is formed under the conditions of a blank diameter of 57 mm and a punch diameter of 33 mm. The sidewall height of the Erichsen cup is measured using, for example, a Roncorder EC1550 - H manufactured by Kosaka Laboratory Ltd.

[0097] Specifically, with the rolling direction as a reference (0° / 180°), the measurement terminal is placed at the opening of the Erichsen cup, and the workbench on which the Erichsen cup is placed is rotated one week to measure the height of the opening at 360° in the circumferential direction.

[0098] When the mathematical formula (4) is satisfied, that is, when the ear ratio is -7.0% or more, the aggregation degree of the cube orientation becomes high. As a result, the number of repeated bends of the alloy plate can be increased.

[0099] <Manufacturing method of aluminum alloy plate>

[0100] For example, the aluminum alloy plate of the present disclosure can be manufactured by the following method. First, an ingot is manufactured from an aluminum alloy having the composition of the aluminum alloy plate of the present disclosure using a semi - continuous casting method (i.e., DC casting) according to a conventional method.

[0101] Next, the surface of the ingot is face - cut. Then, the ingot is placed in a soaking furnace for homogenization treatment. The temperature of the homogenization treatment is preferably, for example, 470°C or more and 620°C or less. The time of the homogenization treatment is preferably, for example, 1 hour or more and 20 hours or less.

[0102] When the temperature of homogenization treatment is 400 °C or higher, it is easy to eliminate the segregation of the ingot structure. In addition, if the temperature of homogenization treatment is 450 °C or higher, Mg2Si particles can be redissolved, thereby improving the tensile strength and toughness of the alloy plate. Further, if the temperature of homogenization treatment is 490 °C or higher, more preferably 550 °C or higher, the redissolution of Mg2Si particles can be promoted, thereby further improving the tensile strength and toughness of the alloy plate. On the other hand, if the temperature during homogenization treatment is 620 °C or lower, the aluminum alloy is not easily locally melted.

[0103] When the homogenization treatment time is 1 hour or longer, the temperature of the entire slab becomes uniform, the segregation of the ingot structure is easily eliminated, and it is easy to redissolve Mg2Si particles. The longer the homogenization treatment time, the more Mg2Si particles can be redissolved. However, when the homogenization treatment time exceeds 20 hours, the effect of homogenization treatment becomes saturated.

[0104] After homogenization treatment, hot rolling is performed on the ingot. The hot rolling process includes a rough rolling process and a finish rolling process. In the rough rolling process, the ingot is processed into a plate with a thickness of about several tens of mm by reversible rolling. In the finish rolling process, for example, the thickness of the plate is reduced to about several mm by tandem rolling or the like, and a hot rolled coil is formed by winding the plate into a coil shape.

[0105] When the total reduction ratio of finish rolling is high, a recrystallized structure is formed after winding, thereby increasing the aggregation degree of cube orientation. When the winding temperature of finish rolling is high, a recrystallized structure is formed after winding, thereby increasing the aggregation degree of cube orientation.

[0106] In addition, by performing solution treatment on the hot rolled coil, Mg and the like are redissolved, thereby obtaining an alloy plate with high strength. For example, by performing heat treatment (i.e., annealing) with a target entity temperature of 440 °C or higher and 30 seconds or longer using a continuous annealing furnace, and then performing forced cooling such as air cooling, the tensile strength of the alloy plate can be effectively improved.

[0107] After hot rolling, cold rolling is performed on the plate. In cold rolling, the hot rolled coil is rolled until the product plate thickness is reached. Cold rolling can be single stand rolling or tandem mill rolling. In single stand cold rolling, it is preferably performed in multiple passes of two or more passes.

[0108] By setting the exit temperature of cold rolling in intermediate passes other than the final pass to 120 °C or higher, Si, Cu, and Mg are finely precipitated and age hardened, thereby improving the tensile strength of the alloy plate. By further increasing the exit temperature to 130 °C or higher, the tensile strength of the alloy plate can be further improved.

[0109] The cold rolling rate (i.e., the target total reduction ratio) is preferably 80% or more. When the cold rolling rate is 80% or more, the tensile strength of the alloy plate can be improved. The lower the cold rolling rate, the more cube orientation remains. The cold rolling rate is preferably 92% or less.

[0110] The cold rolling rate R (%) is calculated by the following mathematical formula (5) using the plate thickness t0 (mm) of the hot rolled plate and the product plate thickness t1 (mm) after cold rolling.

[0111] R = (t0 - t1) / t0 × 100 (5)

[0112] In addition, as long as the effects of the aluminum alloy plate of the present disclosure can be achieved, in the manufacturing method of the above aluminum alloy plate, annealing can be performed, for example, before and after cold rolling or between cold rolling passes.

[0113] The coil cold rolled to the product plate thickness can be pre-coated in a coating line or the like. In the case of pre-coating, the surface of the cold rolled coil is degreased, cleaned, chemically converted, then coated with a coating, and then subjected to a coating baking treatment.

[0114] In the chemical conversion treatment, chemical solutions such as chromates and zirconiums are used. Epoxies, polyesters, etc. are used as coatings. The above chemical solutions and coatings can be selected according to the use. In the coating baking treatment, the coil is heated at a solid temperature (PMT: Peak Metal Temperature) of 220°C or more and 270°C or less for about 30 seconds or less. At this time, the lower the PMT, the more the recovery of the material is suppressed, and thus the tensile strength of the alloy plate can be highly maintained.

[0115] [1 - 2. Effects]

[0116] According to the embodiments described in detail above, the following effects can be obtained.

[0117] (1a) It is possible to mix waste raw materials derived from can materials and at the same time achieve high pull - ring bending strength and high toughness of the aluminum alloy plate. That is, it is possible to mix a certain amount of waste of 3104 aluminum alloy for cans, thereby reducing the usage rate of new base metals and reducing carbon dioxide emissions. In addition, an aluminum alloy plate for pull - rings that achieves both formability and openability can be obtained.

[0118] [2. Other Embodiments]

[0119] The embodiments of the present disclosure have been described above, but the present disclosure is not limited to the above embodiments, and various embodiments can be adopted.

[0120] (2a) In addition to the aluminum alloy plate of the above embodiments, the present disclosure also includes various forms such as components made of the aluminum alloy plate and the manufacturing method of the aluminum alloy plate.

[0121] (2b) The functions of one component in each of the above embodiments may be shared by multiple components, or the functions of multiple components may be integrated into one component. In addition, a part of the configuration of the above embodiments may be omitted. At least a part of the configuration of each of the above embodiments may also be added to the configuration of the above other embodiments, or at least a part of the configuration of each of the above embodiments may be replaced with the configuration of the above other embodiments, etc. In addition, all modes included in the technical idea determined by the statements recited in the claims are embodiments of the present disclosure.

[0122] [3. Examples]

[0123] Hereinafter, the content of the test conducted to confirm the effects of the present disclosure and its evaluation results will be described.

[0124] <Manufacture of Aluminum Alloy Sheets>

[0125] As examples and comparative examples, aluminum alloy sheets S1 - S21 shown in Tables 1 and 2 were manufactured. Hereinafter, the specific manufacturing steps will be described.

[0126] First, ingots containing the components (mass %) of alloy serial numbers 1 - 8 shown in Table 3, with the remaining part consisting of aluminum and inevitable impurities, were manufactured by semi - continuous casting. The ingots contain 0.10 mass % or less of Ti, 0.25 mass % or less of Zn, 0.10 mass % or less of Cr, and 0.15 mass % or less of inevitable impurities.

[0127] Next, face cutting was performed on four surfaces of the ingot except for the front end and the rear end. After that, the ingot was put into a furnace and subjected to homogenization treatment. The temperature of the homogenization treatment is as shown in Table 1. After the homogenization treatment, the ingot was taken out of the furnace and hot rolling was immediately carried out to form a rolled sheet.

[0128] The obtained rolled sheet was annealed. The annealing temperature is as shown in Table 1, and the annealing time is 30 seconds. After annealing, the rolled sheet was cooled to room temperature by air cooling. After cooling, cold rolling was performed on the rolled sheet. The target total reduction ratio during cold rolling is as shown in Table 1.

[0129] After cold rolling, a coating was applied to the sheet surface, and a coating baking treatment was carried out for 30 seconds. The actual temperature (PMT) during coating baking is as shown in Table 1. By baking the coating, aluminum alloy sheets S1 - S21 were obtained. In addition, the sheet thicknesses (i.e., product sheet thicknesses) of aluminum alloy sheets S1 - S21 measured using a micrometer are shown in Table 1.

[0130] [Table 1]

[0131]

[0132] [Table 2]

[0133]

[0134] [Table 3]

[0135]

[0136] <Evaluation of Aluminum Alloy Plate>

[0137] (Tensile Properties)

[0138] Specimen No. 5 specified in JIS-Z-2241:2011 was fabricated from aluminum alloy plates S1 - S21. The longitudinal direction of this specimen extended along the direction at 0° with respect to the rolling direction.

[0139] A tensile test was conducted on this specimen in accordance with JIS-Z-2241:2011, and the tensile strength σ was measured. B_0° . Table 2 shows the measured results of the tensile strength σ. B_0° In addition, the value V of the mathematical formula (1) = (2.7×t - 0.45)×σ was calculated based on the measured results of the plate thickness and the tensile strength. B_0° . The calculation results are shown in Table 2.

[0140] (Toughness)

[0141] For aluminum alloy plates S1 - S21, the ratio (area ratio) of the total area of Mg2Si particles with an area of 0.3 μm 2 or more in the L-ST cross-section was calculated according to the measurement method described in the embodiment. The measurement results are shown in Table 2.

[0142] For aluminum alloy plates S1 - S21, the earring rate was calculated according to the measurement method described in the embodiment and the left side of the mathematical formula (4). The results are shown in Table 2. In addition, "-" in the table indicates non-measurement.

[0143] For aluminum alloy plates S1 - S21, the standardized repeated bending number was calculated according to the measurement method described in the example and the mathematical formulas (2) and (3). The results are shown in Table 2.

[0144] (Scrap Mixing Ratio)

[0145] Regarding the composition of aluminum alloy plates S1 - S21, it was determined whether the possible mixing ratio of 3104 aluminum alloy scrap was 50% by mass or more. The results are shown in Table 2.

[0146] In Table 2, the aluminum alloy sheet marked as "≥50" indicates that it can mix 3104 aluminum alloy with 50% by mass or more. Additionally, the possible mixing ratio of the 3104 aluminum alloy scrap is judged according to Table 4.

[0147] Table 4 shows the correspondence between the mixing ratio of 3104 aluminum alloy and 5182 aluminum alloy and the average value of the composition specifications. The first row of Table 4 is the average value of the composition specifications of 3104 aluminum alloy, and the second row is the average value of the composition specifications of 5182 aluminum alloy.

[0148] For example, when the mixing ratio of 3104 aluminum alloy is 50% by mass, the average value of Si is 0.20% by mass, the average value of Fe is 0.29% by mass, the average value of Cu is 0.11% by mass, the average value of Mn is 0.7% by mass, and the average value of Mg is 2.8% by mass.

[0149] Therefore, when the ratio of each component in the aluminum alloy sheet is equal to or higher than the above values of Si, Fe, Cu, Mn, and Mg, the possible mixing ratio of the 3104 aluminum alloy sheet is 50% by mass or more. The higher the mixing ratio of the 3104 aluminum alloy, the more the contents of Si, Fe, Cu, and Mn increase, and the more the content of Mg decreases. S1 - S21 can mix 3104 aluminum alloy scrap with 50% by mass or more.

[0150] [Table 4]

[0151] alloy Si Fe Cu Mn Mg 3104 0.30 0.40 0.15 1.10 1.05 5182 0.10 0.18 0.08 0.35 4.50 3104 mixing ratio Si Fe Cu Mn Mg 5％ 0.11 0.19 0.08 0.4 4.3 10％ 0.12 0.20 0.08 0.4 4.2 15％ 0.13 0.21 0.09 0.5 4.0 20％ 0.14 0.22 0.09 0.5 3.8 25％ 0.15 0.23 0.09 0.5 3.6 30％ 0.16 0.24 0.10 0.6 3.5 35％ 0.17 0.25 0.10 0.6 3.3 40％ 0.18 0.27 0.11 0.7 3.1 45％ 0.19 0.28 0.11 0.7 2.9 50％ 0.20 0.29 0.11 0.7 2.8 55％ 0.21 0.30 0.12 0.8 2.6 60％ 0.22 0.31 0.12 0.8 2.4 65％ 0.23 0.32 0.12 0.8 2.3 70％ 0.24 0.33 0.13 0.9 2.1 75％ 0.25 0.34 0.13 0.9 1.9 80％ 0.26 0.36 0.14 1.0 1.7 85％ 0.27 0.37 0.14 1.0 1.6 90％ 0.28 0.38 0.14 1.0 1.4 95％ 0.29 0.39 0.15 1.1 1.2 100％ 0.30 0.40 0.15 1.1 1.1

[0152] (Pull - tab bending strength)

[0153] In addition to the aluminum alloy sheets S1 - S21, multiple aluminum alloy sheets with different thicknesses and tensile strengths are prepared, and the pull - tab bending strength of each aluminum alloy sheet is measured respectively according to the measurement method described in the embodiment.

[0154] The measurement results, the thickness t of the aluminum alloy sheet, the tensile strength σ in the 0° direction with respect to the rolling direction B_0° , and the value V of the mathematical formula (1) V=(2.7×t - 0.45)×σ B_0 ° are shown in Table 5 and Figure 4 . In addition, the composition of the aluminum alloy sheet for which the pull - tab bending strength is measured is shown in Table 6.

[0155] It can be confirmed from Figure 4 that there is a high correlation between the value V and the pull - tab bending strength. Additionally, Figure 4 the results of measurement using a pull - tab of the common DRT company - type snap - on pull - tab shape are shown, however, the same tendency can be obtained when using pull - tabs of other shapes.

[0156] [Table 5]

[0157]

[0158] [Table 6]

[0159]

[0160] As shown in Table 2, it can be confirmed that the value V, which has a high correlation with the pull-tab bending strength in aluminum alloy plates S11 to S21, is 67 or more, and the plate thickness and tensile strength capable of obtaining a high pull-tab bending strength are obtained.

Claims

1. An aluminum alloy plate for a pull ring, characterized in that: The content of silicon Si is 0.10 mass % or more and 0.60 mass % or less, The content of iron Fe is 0.20 mass % or more and 0.70 mass % or less, The content of copper Cu is 0.10 mass % or more and 0.40 mass % or less, The content of manganese Mn is 0.5 mass % or more and 1.2 mass % or less, The content of magnesium Mg is 1.1 mass % or more and 4.0 mass % or less, and The remainder consists of aluminum Al and inevitable impurities, or contains the aluminum and the inevitable impurities. Plate thickness t (mm) and tensile strength σ at 0° relative to the rolling direction B_0° (MPa) satisfies the following mathematical formula (1): (2.7×t-0.45)×σ B_0° ≧67 (1)。 2. The aluminum alloy plate for pull ring according to claim 1, characterized in that: On the L-ST cross section, the area is 0.3 μm 2 The total area ratio of the above Mg2Si particles is 1.0% or less.

3. The aluminum alloy plate for pull ring according to claim 1 or 2, characterized in that: In the circumferential direction of the Ericsson cup formed by the Ericsson test, the average value h of the maximum side wall heights of the region near 0° and the region near 180° relative to the rolling direction is 0p The average value h of the maximum side wall heights in the region near 45°, the region near 135°, the region near 225°, and the region near 315° relative to the rolling direction is 45p , and the average value h of the minimum values ​​of the side wall heights in the region from 0° to 45°, the region from 45° to 135°, the region from 135° to 180°, the region from 180° to 225°, the region from 225° to 315°, and the region from 315° to 360° relative to the rolling direction v Satisfies the following mathematical formula (2): (h 0p -h 45p ) / h v ×100≥-7.0 (2)。 4. The aluminum alloy plate for pull ring according to claim 1 or 2, characterized in that: The content of silicon Si is 0.20 mass % or more and 0.60 mass % or less, The content of iron Fe is 0.30 mass % or more and 0.70 mass % or less, The content of copper Cu is 0.11 mass % or more and 0.40 mass % or less, The content of manganese Mn is 0.7 mass % or more and 1.2 mass % or less, The content of magnesium Mg is 1.1 mass % or more and 3.0 mass % or less.

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