JP7473708B1 - Aluminum alloy plate for can lids - Google Patents

Abstract

The present invention provides an aluminum alloy sheet for can ends that is capable of achieving both high strength and high toughness while incorporating scrap raw materials derived from can stock.
[Solution] One aspect of the present disclosure is an aluminum alloy sheet for can ends, which has a silicon (Si) content of 0.20% by mass or more and 0.47% by mass or less, iron (Fe) content of 0.30% by mass or more and 0.70% by mass or less, copper (Cu) content of 0.11% by mass or more and 0.40% by mass or less, manganese (Mn) content of 0.70% by mass or more and 1.20% by mass or less, magnesium (Mg) content of 1.1% by mass or more and 3.7% by mass or less, with the remainder being aluminum (Al) and unavoidable impurities, and has a solidus temperature higher than the solid solution temperature of Mg ₂ Si.
[Selection diagram] None

Description

This disclosure relates to aluminum alloy sheets for can ends.

In recent years, with the rise in environmental awareness, there is a demand for aluminum alloy sheets with low _CO2 emissions during the manufacturing process. In the aluminum manufacturing process, the composition of new aluminum ingots in the casting process indirectly contributes greatly to _CO2 emissions.

The production of primary aluminum ingots consumes a large amount of electricity during the refining process, which leads to a large amount of _CO2 emissions. Therefore, reducing the amount of primary aluminum ingots mixed and increasing the horizontal recycling rate will lead to a reduction in _CO2 emissions in the production of aluminum alloy sheets.

It is generally said that _CO2 emissions when aluminum scrap is remelted and cast can be reduced to about one-thirtieth of that when new aluminum ingots are produced. In particular, the production volume of aluminum alloy plates for beverage cans used around the world is extremely large, and further improving the horizontal recycling rate of these cans is of great significance in reducing the environmental impact.

Among these, can ends made of 5182 aluminum alloy (AA5182 alloy) have lower upper limits for the compositional standards of Si, Fe, Cu, Mn, etc. than can bodies made of 3104 aluminum alloy (AA3104 alloy), making it difficult to mix with scrap derived from can materials that contain 3104 aluminum alloy.

For example, if can scrap (UBC: Used Beverage Can) generated in the city is mixed as is, it will contain more 3104 aluminum alloy components due to the weight ratio between the can body and the can lid, which will easily exceed the upper limit of the 5182 aluminum alloy components, making it necessary to dilute the components with new metal.

For this reason, aluminum alloy sheets for can ends use more virgin metal than aluminum alloy sheets for can bodies, and are adjusted to have the same composition as 5182 aluminum alloy, resulting in a low recycling rate. Therefore, by changing can ends to an alloy whose composition is easily blended with 3104 aluminum alloy, the rate of virgin metal usage for can ends can be significantly reduced.

Patent documents 1-5 disclose aluminum alloy sheets for can ends that are relatively close to the composition of 3104 aluminum alloy, which has excellent recyclability.

JP 2001-73106 A Japanese Patent Application Laid-Open No. 9-070925 Japanese Patent Application Laid-Open No. 11-269594 JP 2000-160273 A JP 2016-160511 A

One of the issues with making the alloy for can lids closer in composition to 3104 aluminum alloy is the reduction in the pressure resistance of the can lids and the toughness of the material. The pressure resistance of a can lid is the internal pressure value when the can lid is inverted against the pressure inside the can, and is the resistance value when the internal pressure of the can unexpectedly increases due to a change in the external environment.

Positive pressure cans, particularly those used for beer and carbonated beverages, require high pressure resistance. In general, the stronger the material and the thicker the plate, the higher the pressure resistance. For this reason, high-strength 5182 aluminum alloy, which contains a large amount of Mg, is used for the lids of positive pressure cans.

In contrast, if conventional 3104 aluminum alloy is used for can lids, the pressure resistance is significantly reduced, and if the internal pressure of the can suddenly increases, the lid will likely invert, causing the contents to leak. Furthermore, increasing the plate thickness to increase the pressure resistance will result in an increase in the weight and cost of the lid.

Furthermore, the toughness of the material affects the formability and openability of the lid. If the material has low toughness, forming cracks may occur, especially in the rivet and countersink parts of the lid. Also, if the internal pressure of the can suddenly increases, cracks may occur in the score area, increasing the risk of the can contents leaking. In particular, these cracks occur along the rolling direction. Therefore, toughness against tensile stress and bending stress in the direction perpendicular to the rolling direction is required.

However, aluminum alloy sheets for can lids that are relatively close in composition to the conventional 3104 aluminum alloy do not satisfy either or both of the two issues mentioned above, namely, material strength (i.e., pressure resistance of the lid) and toughness (i.e., formability and openability).

One aspect of the present disclosure aims to provide an aluminum alloy sheet for can ends that combines high strength and high toughness while incorporating scrap raw materials derived from can stock.

One aspect of the present disclosure is an aluminum alloy sheet for can ends, the aluminum alloy sheet having a silicon (Si) content of 0.20 mass% or more and 0.47 mass% or less, an iron (Fe) content of 0.30 mass% or more and 0.70 mass% or less, a copper (Cu) content of 0.11 mass% or more and 0.40 mass% or less, a manganese (Mn) content of 0.70 mass% or more and 1.20 mass% or less, a magnesium (Mg) content of 1.1 mass% or more and 3.7 mass% or less, the balance being aluminum (Al) and unavoidable impurities, and having a solidus temperature higher than the solid solution temperature of Mg ₂ Si.

According to this configuration, the solidus temperature of the aluminum alloy can be made higher than the solution temperature of the _Mg2Si crystallized matter, and therefore, by subjecting the aluminum alloy ingot to a soaking treatment within this temperature range, it is expected that the _Mg2Si crystallized matter, which causes cracks and unexpected openings during molding, can be suppressed.

As a result, it is possible to obtain an aluminum alloy sheet having both high strength and high toughness while blending scrap raw materials derived from can materials. That is, it is possible to blend a certain amount of scrap 3104 aluminum alloy for can bodies, thereby reducing the usage rate of new ingots and reducing _CO2 emissions. Furthermore, it is possible to obtain an aluminum alloy sheet for can ends that has high formability and can be used for positive pressure can ends that require high pressure resistance.

Hereinafter, embodiments to which the present disclosure is applied will be described.
[1. First embodiment]
[1-1. Configuration]
<Composition>
The aluminum alloy sheet for can ends (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).

The lower limit of the Si content is 0.20 mass%. The average Si content standard for 3104 aluminum alloys specified in JIS-H-4000:2014 is 0.30 mass%, and the average Si content standard for 5182 aluminum alloys specified in JIS-H-4000:2014 is 0.10 mass%. Therefore, by making the Si content 0.20 mass% or more, a large amount of 3104 aluminum alloy scrap can be blended.

The upper limit of the Si content is 0.47 mass%, and preferably 0.39 mass%. If the Si content exceeds 0.47 mass%, the difference between the solidus temperature of Mg ₂ Si and the solidus temperature of the Al matrix becomes small, making it difficult to dissolve the Mg ₂ Si present in the ingot in the homogenization process. In addition, coarse Mg ₂ Si is newly precipitated during hot rolling. As a result, the strength and toughness of the alloy are reduced.

In addition, by setting the Si content to 0.39 mass % or less, Mg ₂ Si can be easily dissolved in the homogenization treatment process. Furthermore, precipitation of coarse Mg ₂ Si in hot rolling is suppressed, and good strength and toughness can be obtained without performing a heat treatment process after hot rolling.

The lower limit of the Fe content is 0.30% by mass. The average Fe content standard for 3104 aluminum alloy is 0.40% by mass, and the average Fe content standard for 5182 aluminum alloy is 0.18% by mass. Therefore, by making the Fe content 0.30% by mass or more, it is possible to mix in a large amount of 3104 aluminum alloy scrap.

The upper limit of the Fe content is 0.70 mass%, preferably 0.59 mass%, and more preferably 0.51 mass%. If the Fe content exceeds 0.70 mass%, the amount of abnormally coarse Al-Fe-Mn or Al-Fe-Mn-Si intermetallic compounds (i.e. giant compounds) increases. As a result, crack propagation paths are created and the toughness of the alloy plate decreases. Also, if the Fe content is 0.51 mass% or less, the crystallization of the above-mentioned coarse intermetallic compounds is suppressed, while strength and toughness can be compensated for by adding a large amount of Mg.

The lower limit of the Cu content is 0.11 mass%, preferably 0.17 mass%, and more preferably 0.20 mass%. If the Cu content is less than 0.11 mass%, there will be a shortage of Cu, which increases strength through solid solution or precipitation, and the strength of the alloy plate will decrease. In addition, the average value of the Cu content standard for 3104 aluminum alloy is 0.15 mass%, and the average value of the Cu content standard for 5182 aluminum alloy is 0.075 mass%. Therefore, by making the Cu content 0.11 mass% or more, a large amount of 3104 aluminum alloy scrap can be blended.

The upper limit of the Cu content is 0.40 mass%, and 0.25 mass% is preferable. If the Cu content exceeds 4.0 mass%, the amount of coarse precipitates increases, and the toughness of the alloy plate decreases. In addition, by setting the Cu content to 0.25 mass% or less, the strength can be increased without significantly impairing the toughness.

The lower limit of the Mn content is 0.70 mass%. If the Mn content is less than 0.70 mass%, there will be a shortage of Mn, which increases strength through solid solution or precipitation, and the average strength of the alloy plate will decrease. In addition, the average value of the Mn content standard for 3104 aluminum alloy is 1.1 mass%, and the average value of the Mn content standard for 5182 aluminum alloy is 0.35 mass%. Therefore, by setting the Mn content to 0.70 mass% or more, more 3104 aluminum alloy scrap can be blended compared to the conventional 5182 aluminum alloy.

The upper limit of the Mn content is 1.20 mass%, preferably 0.98 mass%, and more preferably 0.92 mass%. If the Mn content exceeds 1.20 mass%, the amount of abnormally coarse Al-Fe-Mn or Al-Fe-Mn-Si intermetallic compounds increases. As a result, crack propagation paths are created, and the toughness of the alloy plate decreases.

The lower limit of the Mg content is 1.1% by mass. If the Mg content is less than 1.1% by mass, there will be a shortage of Mg, which increases strength through solid solution, and the average strength of the alloy plate will decrease. In addition, by precipitating Mg during hot rolling and cold rolling after solution treatment, the strength of the alloy plate will increase significantly.

The upper limit of the Mg content is 3.7% by mass, preferably 3.3% by mass, more preferably 3.1% by mass, and even more preferably 2.9% by mass. If the Mg content exceeds 3.7% by mass, the solidus temperature of the Al matrix decreases and the dissolution temperature of Mg ₂ Si increases, making it difficult to dissolve Mg ₂ Si present in the ingot in the homogenization process. In addition, the solidus temperature of the Al matrix decreases, and the amount of coarse Al-Fe-Mn or Al-Fe-Mn-Si intermetallic compounds increases. Therefore, strength and toughness are impaired.

The alloy plate may contain titanium (Ti). The upper limit of the Ti content is preferably 0.10 mass%. The ingot structure of the alloy plate is refined by including Ti. On the other hand, if there is too much Ti, it may cause inclusions and reduce toughness. The alloy plate may also contain zinc (Zn). The upper limit of the Zn content is preferably 0.25 mass%. Furthermore, the alloy plate may contain chromium (Cr). The upper limit of the Cr content is preferably 0.10 mass%.

The alloy plate may contain unavoidable impurities to the extent that the performance of the alloy plate is not significantly impaired. In other words, the alloy plate contains Si, Fe, Cu, Mn, Mg, Ti, Zn, and Cr in the above-mentioned ranges, with the remainder being Al and unavoidable impurities. The upper limit of the total amount of unavoidable impurities is preferably 0.15 mass%.

<Calculation of phase diagrams using computer software>
In the alloy plate of the present disclosure, in order to increase the toughness of the material, it is preferable to re-dissolve Mg ₂ Si particles, which become the initiation points and propagation paths of cracks and affect the decrease in toughness, in a homogenization heat treatment step of the ingot.

In order to redissolve Mg ₂ Si while avoiding local melting of the Al matrix, the solidus temperature must be higher than the solution temperature of Mg ₂ Si. Furthermore, it is preferable that the temperature difference obtained by subtracting the solution temperature of Mg ₂ Si from the solidus temperature is 30° C. or more. By having the solution temperature of Mg ₂ Si lower than the solidus temperature, coarse crystals are not generated during casting, and performance degradation due to coarse crystals can be avoided.

Furthermore, in a material in which the crystallization temperature of Al ₆ (Mn,Fe) is higher than the solidification start temperature of Al, Al ₆ (Mn,Fe) is generated as coarse crystals during casting, which leads to molding defects such as pinholes. Therefore, it is preferable that the solidification start temperature of Al is higher than the crystallization temperature of the primary crystal (i.e., Al ₆ (Mn,Fe)), and it is even more preferable that the temperature difference obtained by subtracting the crystallization temperature of the primary crystal from the solidification start temperature of Al is 1°C or more.

When Al ₆ (Mn, Fe) crystallizes, Al ₆ (Mn, Fe) tends to grow into giant crystals when the surrounding area is liquid phase Al. Such giant crystals can be the starting point for crack propagation in the alloy, leading to a decrease in toughness. When the solidification start temperature of Al is higher than the crystallization temperature of Al ₆ (Mn, Fe), the surrounding Al has already started solidifying when Al ₆ (Mn, Fe) crystallizes, so that the generation of giant crystals is suppressed, and an aluminum alloy sheet for can ends with higher toughness can be obtained.

The solid solution temperature of Mg ₂ Si referred to here means the highest temperature at which Mg ₂ Si can exist in the equilibrium diagram, and is the lowest temperature at which a liquid phase can exist. The solidification start temperature of Al means the highest temperature at which solid phase Al can exist in the equilibrium diagram, and the crystallization temperature of the primary crystal is the highest temperature at which Al ₆ (Mn,Fe) can exist.

The solution temperature of Mg ₂ Si, the solidus temperature of the aluminum alloy, the solidification start temperature of Al, and the crystallization temperature of the primary crystals are obtained from an equilibrium phase diagram of the aluminum alloy calculated using thermodynamic calculation software.

The solution temperature of _Mg2Si , the solidus temperature of the aluminum alloy, the solidification start temperature of Al, and the crystallization temperature of the primary crystal are uniquely determined by the composition of the aluminum alloy. As a method for determining these boundary temperatures from the alloy composition, there is a method of calculating the thermodynamic quantities required for each calculation by the CALPHAD method.

Such thermodynamic calculations for multi-component alloys can be performed using commercially available system software (e.g., "JMatPro" developed by Sente Software) that combines the thermodynamic database, interface, and phase diagram creation functions required for the calculations.

<Method of manufacturing aluminum alloy sheet>
The aluminum alloy plate of the present disclosure can be produced, for example, as follows: First, an aluminum alloy having the composition of the aluminum alloy plate of the present disclosure is subjected to a semi-continuous casting method (i.e., DC casting) according to a conventional method to produce an ingot.

Next, the four faces of the ingot, excluding the front and rear ends, are chamfered. The ingot is then placed in a soaking furnace for homogenization. The temperature in the homogenization is preferably, for example, 470°C or higher and 620°C or lower. The time for the homogenization is preferably, for example, 1 hour or higher and 20 hours or lower.

When the temperature in the homogenization treatment is 400°C or higher, the segregation of the ingot structure is easily eliminated. Furthermore, when the temperature in the homogenization treatment is 450°C or higher, the Mg ₂ Si particles are redissolved, and the strength and toughness of the alloy plate can be improved. Furthermore, when the temperature in the homogenization treatment is 490°C or higher, preferably 550°C or higher, and more preferably the solution temperature of Mg ₂ Si or higher, the redissolution of the Mg ₂ Si particles is promoted, and the strength and toughness of the alloy plate can be further improved. On the other hand, when the temperature in the homogenization treatment is 620°C or lower, more preferably the solidus temperature or lower, local melting of the aluminum alloy is difficult to occur.

When the homogenization treatment time is 1 hour or more, the temperature of the entire ingot becomes uniform, segregation of the ingot structure is easily eliminated, and Mg ₂ Si particles are easily redissolved. The longer the homogenization treatment time, the more the Mg ₂ Si particles can be redissolved. However, when the homogenization treatment time exceeds 20 hours, the effect of the homogenization treatment becomes saturated.

After the homogenization treatment, the ingot is subjected to hot rolling. 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 material with a thickness of about several tens of mm by reverse rolling. In the finish rolling process, the thickness of the plate material is reduced to about several mm by, for example, tandem rolling, and the plate material is wound into a coil to form a hot rolled coil.

If the total reduction rate of the finish rolling is high, the recrystallized structure will be formed after coiling, and the concentration of isotropic cube orientation can be increased. If the coiling temperature of the finish rolling is high, the recrystallized structure will be formed after coiling, and the concentration of cube orientation can be increased. Increasing the concentration of cube orientation in the aluminum alloy sheet improves toughness.

Following hot rolling, the plate material is cold rolled. In cold rolling, the hot rolled coil is rolled until the product plate thickness is reached. Cold rolling may be either single rolling or tandem rolling. When cold rolling by single rolling, it is recommended to perform rolling in multiple passes, such as two or more passes.

By setting the cold rolling temperature at 120°C or higher in intermediate passes other than the final pass, Si, Cu, Mg, etc. will precipitate finely and age harden, increasing the strength of the alloy plate. Furthermore, by setting the temperature at 130°C or higher, the strength of the alloy plate can be further increased.

The cold rolling reduction ratio (i.e. the total reduction ratio) is preferably 80% or more. When the cold rolling reduction ratio is 80% or more, the strength of the alloy plate can be increased. On the other hand, the cold rolling reduction ratio is preferably 92% or less. By setting the cold rolling reduction ratio to 92% or less, the anisotropy of the crystal grain structure is reduced, and the toughness against tensile stress and bending stress in the direction perpendicular to the rolling direction is improved.

The cold rolling reduction ratio R (%) is calculated by the following formula (1) using the thickness t ₀ (mm) of the hot rolled sheet after hot finish rolling and the thickness t ₁ (mm) of the product after cold rolling.
R = (t ₀ -t ₁ ) / t ₀ × 100 ... (1)

The product plate thickness can be appropriately selected to obtain the desired pressure resistance. Although the pressure resistance improves as the plate thickness increases, the aluminum alloy plate disclosed herein can suppress an increase in plate thickness required to maintain high pressure resistance.

In addition, in the above-mentioned method for producing an aluminum alloy sheet, annealing may be performed, for example, before or after cold rolling or between passes, as long as the effects of the aluminum alloy sheet disclosed herein are achieved.

After the coils have been cold-rolled to the product thickness, they are pre-coated on a painting line or similar. The surface of the cold-rolled coils is degreased, cleaned, and chemically treated, and then painted, after which the paint is baked.

Chemical solutions such as chromate-based and zirconium-based are used in the chemical treatment. Epoxy-based and polyester-based paints are used. These can be selected according to the application. In the paint baking process, the coil is heated to a peak metal temperature (PMT) of 220°C to 270°C for approximately 30 seconds or less. The lower the PMT, the more the material recovery is suppressed, and the higher the strength of the alloy plate can be maintained.

[1-2. Effects]
According to the embodiment described above in detail, the following effects can be obtained.
(1a) The solidus temperature of the aluminum alloy can be made higher than the solution temperature of _Mg2Si crystallized matter. Therefore, by subjecting an aluminum alloy ingot to a soaking treatment within this temperature range, it is expected that the formation of _Mg2Si crystallized matter, which causes cracks and unexpected openings during molding, can be suppressed.

As a result, it is possible to obtain an aluminum alloy sheet having both high strength and high toughness while blending scrap raw materials derived from can materials. That is, it is possible to blend a certain amount of scrap 3104 aluminum alloy for can bodies, thereby reducing the usage rate of new ingots and reducing _CO2 emissions. Furthermore, it is possible to obtain an aluminum alloy sheet for can ends that has high formability and can be used for positive pressure can ends that require high pressure resistance.

2. Other embodiments
Although the embodiments of the present disclosure have been described above, it goes without saying that the present disclosure is not limited to the above-described embodiments and can take various forms.

(2a) In addition to the aluminum alloy plate of the above embodiment, the present disclosure also includes various forms of components made of this aluminum alloy plate and methods for manufacturing this aluminum alloy plate.

(2b) The function of one component in the above embodiments may be distributed among multiple components, or the functions of multiple components may be integrated into one component. In addition, part of the configuration of the above embodiments may be omitted. In addition, at least part of the configuration of the above embodiments may be added to or substituted for the configuration of another of the above embodiments. All aspects included in the technical idea identified from the wording of the claims are embodiments of the present disclosure.

3. Examples
The following describes the tests conducted to confirm the effects of the present disclosure and the evaluation results thereof.

<Calculation of equilibrium phase diagram>
As examples and comparative examples, the equilibrium diagrams of aluminum alloys S1-S14 shown in Table 1 were calculated using "JMatPro" by the calculation method described in the embodiment. The results are shown in Table 1.

<Evaluation of Aluminum Alloy Sheets>
(Various temperatures)
In S2-S9 and S11-S14, the solidus temperature is higher than the Mg ₂ Si solid solution temperature, so these alloys can be soaked at a temperature at which Mg ₂ Si can be dissolved.

In S1, since the amount of Si is relatively large, the Mg ₂ Si solid solution temperature is higher than the solidus temperature, and as a result, when the temperature rises, Al melts locally before Mg ₂ Si dissolves, making it difficult to perform soaking to dissolve Mg ₂ Si.

On the other hand, in S2, the amount of Si is less than that in S1, so there is a temperature range in which the liquid phase does not appear even at the temperature where Mg ₂ Si dissolves. In addition, in S3, the amount of Si is even less than that in S2, so the temperature difference between the solidus temperature and the Mg ₂ Si dissolution temperature is large, at 30° C. or more. As a result, in S3, there is a temperature range in which soaking is possible even taking into account manufacturing variations.

In S4, since the Fe content is relatively large, the crystallization temperature of Al ₆ (Mn, Fe) is higher than the solidification start temperature of Al, and therefore, in S4, Al ₆ (Mn, Fe) may crystallize in the Al liquid phase as it is cooled, and this may become a giant crystallized product.

On the other hand, in S5, the amount of Fe is less than that in F4, so the Al solidification start temperature is higher than the crystallization temperature of Al ₆ (Mn, Fe). Therefore, in S5, the generation of giant crystallized particles is suppressed. In addition, in S6, the amount of Fe is even less than that in F5, so the difference between the Al solidification start temperature and the crystallization temperature of Al ₆ (Mn, Fe) is large. Therefore, in S6, the decrease in strength and toughness due to giant crystallized particles is less likely to occur.

In S7, since the Mn content is relatively large, the crystallization temperature of Al ₆ (Mn, Fe) is higher than the solidification start temperature of Al, and therefore, in S7, Al ₆ (Mn, Fe) may crystallize in the Al liquid phase as it is cooled, resulting in the formation of giant crystals.

On the other hand, in S8, the Mn content is less than that in S7, so the Al solidification start temperature is higher than the crystallization temperature of Al ₆ (Mn, Fe). Therefore, in S8, the generation of giant crystallized particles is suppressed. In addition, in S9, the Mn content is even less than that in S8, so the difference between the Al solidification start temperature and the crystallization temperature of Al ₆ (Mn, Fe) is large. Therefore, in S9, the decrease in strength and toughness due to giant crystallized particles is less likely to occur.

In S10, the Mg content is relatively large, so the Mg ₂ Si solid solution temperature is higher than the solidus temperature. Therefore, in S10, when the temperature rises, Al melts locally before Mg ₂ Si dissolves, making it difficult to perform the soaking homogenization treatment to dissolve Mg ₂ Si. Also, in S10, the crystallization temperature of Al ₆ (Mn, Fe) is higher than the Al solidification start temperature. Therefore, in S10, Al ₆ (Mn, Fe) crystallizes in the Al liquid phase as it is cooled, becoming giant crystals, which causes a decrease in strength and toughness.

On the other hand, in S11, since the amount of Mg is less than that in S10, there exists a temperature range where the liquid phase does not appear even at the temperature where _Mg2Si is dissolved. Also, in S12, since the amount of Mg is even less than that in S11, the solidification start temperature of Al is higher than the crystallization temperature of _Al6 (Mn,Fe). Therefore, the formation of giant crystals is suppressed in S12.

In S13, the Mg content is even less than in S12, and therefore the temperature difference between the solidus temperature and the Mg ₂ Si solid solution temperature is large, being 30° C. or more. As a result, in S13, there exists a temperature range in which soaking is possible even taking into account manufacturing variations.

In addition, since the Mg content in S14 is smaller than that in S13, the difference between the Al solidification start temperature and the crystallization temperature of Al ₆ (Mn,Fe) becomes larger, and therefore S14 is less susceptible to deterioration in strength and toughness due to giant crystallized particles.

(scrap mixture rate)
Table 2 shows the relationship between the blend ratio of 3104 aluminum alloy and 5182 aluminum alloy and the average values of the component specifications. The first line of Table 2 shows the average values of the component specifications of 3104 aluminum alloy, and the second line shows the average values of the component specifications of 5182 aluminum alloy.

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

Therefore, when the proportion of each component in the aluminum alloy plate is equal to or greater than the above values for Si, Fe, Cu, Mn, and Mg, the possible blending ratio of 3104 aluminum alloy plate is 50% by mass or more. As the blending ratio of 3104 aluminum alloy increases, the contents of Si, Fe, Cu, and Mn increase and the Mg content decreases. Aluminum alloy plates S1-S14 can be blended with 50% by mass or more of 3104 aluminum alloy scrap.

Claims (3)

The silicon (Si) content is 0.20% by mass or more and 0.47% by mass or less,
The iron (Fe) content is 0.30 mass% or more and 0.70 mass% or less,
The copper (Cu) content is 0.11% by mass or more and 0.40% by mass or less,
The manganese (Mn) content is 0.70 mass% or more and 1.20 mass% or less,
The magnesium (Mg) content is 3.0 % by mass or more and 3.7% by mass or less,
The balance is aluminum (Al) and unavoidable impurities,
An aluminum alloy sheet for can ends, having a solidus temperature higher than the solid solution temperature of Mg ₂ Si. The aluminum alloy sheet for can lids according to claim 1,
The silicon (Si) content is 0.20% by mass or more and 0.47% by mass or less,
The iron (Fe) content is 0.30 mass% or more and 0.59 mass% or less,
The copper (Cu) content is 0.11 mass% or more and 0.40 mass% or less,
The manganese (Mn) content is 0.70% by mass or more and 0.98% by mass or less,
The magnesium (Mg) content is 3.0 % by mass or more and 3.3% by mass or less,
An aluminum alloy sheet for can ends, in which the solidification start temperature of Al is higher than the crystallization temperature of the primary crystal. The aluminum alloy sheet for can ends according to claim 2,
The silicon (Si) content is 0.20% by mass or more and 0.39% by mass or less,
The iron (Fe) content is 0.30 mass% or more and 0.59 mass% or less,
The copper (Cu) content is 0.11 mass% or more and 0.40 mass% or less,
The manganese (Mn) content is 0.70% by mass or more and 0.98% by mass or less,
The magnesium (Mg) content is 3.0 % by mass or more and 3.1% by mass or less,
An aluminum alloy sheet for can ends, the temperature difference between the solidus temperature and the solution temperature of Mg ₂ Si being 30° C. or more.