Aluminum alloy sheet for beverage can body

Abstract

To provide an aluminum alloy sheet for a beverage can body having excellent chime wrinkle resistance and ironing moldability.SOLUTION: An aluminum alloy sheet for a beverage can body has a composition comprising 0.10 mass% or more and 0.70 mass% of Si, 0.10 mass% or more and 0.80 mass% or less of Fe, 0.10 mass% or more and 0.30 mass% or less of Cu, 0.50 mass% or more and 1.50 mass% or less of Mn, 1.00 mass% or more and 1.50 mass% or less of Mg, with the balance being Al and inevitable impurities. The n value in the range of equivalent plastic strains from 0.01 to 0.03 is 0.049 or more. The n value in the range of equivalent plastic strains from 0.3 to 1.1 is 0.063 or less.SELECTED DRAWING: None

Description

Technical Field

[0001] The present disclosure relates to an aluminum alloy sheet for a beverage can body.

Background Art

[0002] As a beverage can made of an aluminum alloy, there is a two-piece can. The can body of the two-piece can is manufactured by performing a drawing process, a redrawing process, and an ironing process on an aluminum alloy sheet for a beverage can body. In recent years, due to the need to reduce the cost of beverage cans, thinning of the can body, thinning of the blank sheet, and strengthening of the blank sheet have been demanded. However, thinning of the blank sheet tends to cause a shape defect called chime wrinkle.

[0003] In the redrawing process, when the amount of material flowing into the chime portion increases, the circumferential compressive stress increases due to diameter reduction, and chime wrinkles are likely to occur. Since the occurrence of chime wrinkles is a buckling phenomenon, the thinner the blank sheet, the more likely chime wrinkles are to occur. Ironing formability refers to the difficulty of can body breakage and the difficulty of generating appearance defects during ironing forming.

[0004] Patent Documents 1 to 3 propose a technique for improving chime wrinkles by increasing the work hardening index n value in an aluminum alloy sheet for a beverage can body. However, when simply improving the work hardening index n value by the methods described in Patent Documents 1 to 3, the stress in the can side wall portion during ironing forming increases. As a result, breakage (i.e., can body breakage) is likely to occur in the can side wall portion, and the ironing formability decreases.

[0005] Patent Document 4 proposes a technique for achieving both chime wrinkle resistance and ironing formability by increasing the work hardening index n value in an aluminum alloy sheet for a beverage can body while setting the increase amounts of the work hardening rate and the tensile strength to be below specified values.

Prior Art Documents

Patent Documents

[0006] Patent Document 1 Japanese Unexamined Patent Application Publication No. 2004-300537 Patent Document 2 Japanese Unexamined Patent Application Publication No. 2006-283112 Patent Document 3 Japanese Unexamined Patent Application Publication No. 2006-291326 Patent Document 4 WO2016 / 002226 Publication Summary of the Invention Problems to be Solved by the Invention

[0007] However, in the case of high-strength aluminum alloy sheets for beverage can bodies, the technology described in Patent Document 4 is insufficient, and further improvement in chime wrinkle resistance and ironing formability is required. One aspect of the present disclosure aims to provide an aluminum alloy sheet for beverage can bodies that is excellent in chime wrinkle resistance and ironing formability. Means for Solving the Problems

[0008] One aspect of the present disclosure is an aluminum alloy sheet for beverage can bodies containing Si: 0.10% by mass or more and 0.70% by mass or less, Fe: 0.10% by mass or more and 0.80% by mass or less, Cu: 0.10% by mass or more and 0.30% by mass or less, Mn: 0.50% by mass or more and 1.50% by mass or less, Mg: 1.20% by mass or more and 1.50% by mass or less, with the balance being Al and unavoidable impurities, having an n-value in the range of 0.049 or more when the equivalent plastic strain is in the range of 0.01 to 0.03, and an n-value in the range of 0.063 or less when the equivalent plastic strain is in the range of 0.3 to 1.1.

[0009] The aluminum alloy sheet for beverage can bodies, which is one aspect of the present disclosure, has high strength and is excellent in chime wrinkle resistance and ironing formability. Another aspect of the present disclosure is an aluminum alloy sheet for a beverage can body, which contains Si: 0.10% by mass or more and 0.70% by mass or less, Fe: 0.10% by mass or more and 0.80% by mass or less, Cu: 0.10% by mass or more and 0.30% by mass or less, Mn: 0.50% by mass or more and 1.50% by mass or less, Mg: 1.20% by mass or more and 1.50% by mass or less, with the balance being Al and inevitable impurities, and has a tensile strength of 315 MPa or more and 350 MPa or less, an n value of 0.049 or more in the range of equivalent plastic strain of 0.01 to 0.03, and an n value of 0.063 or less in the range of equivalent plastic strain of 0.3 to 1.1. The aluminum alloy sheet for a beverage can body, which is another aspect of the present disclosure, has high strength and excellent chime wrinkle resistance and ironing formability. Another aspect of the present disclosure is an aluminum alloy sheet for a beverage can body, which contains Si: 0.10% by mass or more and 0.70% by mass or less, Fe: 0.10% by mass or more and 0.80% by mass or less, Cu: 0.10% by mass or more and 0.30% by mass or less, Mn: 0.50% by mass or more and 1.50% by mass or less, Mg: 1.20% by mass or more and 1.50% by mass or less, with the balance being Al and inevitable impurities, an n value of 0.049 or more in the range of equivalent plastic strain of 0.01 to 0.03, and an n value of 0.063 or less in the range of equivalent plastic strain of 0.3 to 1.1, and the amount of Mg in solid solution calculated from the difference in specific resistance from an aluminum alloy hot-rolled sheet cooled immediately after hot finish rolling is 1.20% by mass or more after rolling in the range of equivalent plastic strain of 0.3 to 1.1. The aluminum alloy sheet for a beverage can body, which is another aspect of the present disclosure, has high strength and excellent chime wrinkle resistance and ironing formability. Another aspect of the present disclosure is an aluminum alloy consisting of Si: 0.10 mass% or more and 0.70 mass% or less, Fe: 0.10 mass% or more and 0.80 mass% or less, Cu: 0.10 mass% or more and 0.30 mass% or less, Mn: 0.50 mass% or more and 1.50 mass% or less, Mg: 1.20 mass% or more and 1.50 mass% or less, with the balance being Al and unavoidable impurities, having a tensile strength of 315 MPa or more and 350 MPa or less, an n value of 0.049 or more in the range of equivalent plastic strain of 0.01 to 0.03, an n value of 0.063 or less in the range of equivalent plastic strain of 0.3 to 1.1, a Mg solid solution amount calculated from the resistivity difference from an aluminum alloy hot-rolled sheet cooled immediately after hot finish rolling of 0.96 mass% or more, and after rolling in the range of equivalent plastic strain of 0.3 to 1.1, the Mg solid solution amount is 1.20 mass% or more, which is an aluminum alloy sheet for beverage can bodies. The aluminum alloy sheet for beverage can bodies, which is another aspect of the present disclosure, has high strength and excellent chime wrinkle resistance and ironing formability.

Embodiments for Carrying Out the Invention

[0010] Exemplary embodiments of the present disclosure will be described. 1. Configuration of Aluminum Alloy Sheet for Beverage Can Bodies (1-1) Composition of Aluminum Alloy Sheet for Beverage Can Bodies The aluminum alloy sheet for beverage can bodies of the present disclosure contains 0.10 mass% or more and 0.70 mass% or less of Si. Si contributes to the formation of Mg-Si-based intermetallic compounds, Al-Mg-Cu-Si-based intermetallic compounds, and Al-Mn-Fe-Si-based intermetallic compounds. The Al-Mn-Fe-Si-based intermetallic compound suppresses adhesion of the aluminum alloy sheet for beverage can bodies to the die mold during ironing. The Al-Mn-Fe-Si-based intermetallic compound is in the α phase. The Al-Mn-Fe-Si-based intermetallic compound is an extremely high-hardness intermetallic compound. The Al-Mn-Fe-Si-based intermetallic compound has the effect of improving the surface properties of the can body material by solid lubrication during DI forming.

[0011] When the Si content is 0.10 mass% or more, an Al-Mn-Fe-Si-based intermetallic compound is sufficiently formed. When the Si content is 0.70 mass% or less, an excessive increase in the amounts of the Mg-Si-based intermetallic compound, the Al-Mg-Cu-Si-based intermetallic compound, and the Al-Mn-Fe-Si-based intermetallic compound can be suppressed. As a result, the solid solution amount of Mg in the aluminum alloy sheet for beverage can bodies increases, and the material strength becomes higher. Further, after subjecting the aluminum alloy sheet for beverage can bodies to rolling equivalent to ironing, the solid solution amount of Mg increases, the second n value becomes lower, and the ironing formability is improved. The rolling equivalent to ironing is rolling such that the equivalent plastic strain is in the range of 0.3 to 1.1. Note that the second n value is the n value in the range where the equivalent plastic strain is from 0.3 to 1.1.

[0012] The aluminum alloy sheet for beverage can bodies of the present disclosure contains 0.10 mass% or more and 0.80 mass% or less of Fe. Fe contributes to the formation of the Al-Mn-Fe-Si-based intermetallic compound. When the Fe content is 0.10 mass% or more, the Al-Mn-Fe-Si-based intermetallic compound is sufficiently formed.

[0013] When the Fe content is 0.80 mass% or less, an excessive increase in the size and amount of the Al-Mn-Fe-Si-based intermetallic compound can be suppressed, and cracks during ironing due to the coarse Al-Mn-Fe-Si-based intermetallic compound can be suppressed. As a result, the ironing formability of the aluminum alloy sheet for beverage can bodies is improved.

[0014] The aluminum alloy sheet for beverage can bodies of the present disclosure contains 0.10 mass% or more and 0.30 mass% or less of Cu. Cu is an element that contributes to the material strength.

[0015] The Cu content shall be 0.10% by mass or more. When the Cu content is 0.10% by mass or more, the solid solution amount of Cu can be optimized. When the solid solution amount of Cu is optimal, the material strength of the aluminum alloy sheet for beverage can bodies is improved. Also, the Cu content shall be 0.30% by mass or less. When the Cu content is 0.30% by mass or less, it is difficult for the material strength of the aluminum alloy sheet for beverage can bodies to become excessively high. As a result, the ironing formability of the aluminum alloy sheet for beverage can bodies is improved.

[0016] The aluminum alloy sheet for beverage can bodies of the present disclosure contains 0.50% by mass or more and 1.50% by mass or less of Mn. Mn contributes to the improvement of the strength of the aluminum alloy sheet for beverage can bodies and also contributes to the formation of Al-Mn-Fe-Si based intermetallic compounds. When the Mn content is 0.50% by mass or more, the strength of the aluminum alloy sheet for beverage can bodies is further improved and Al-Mn-Fe-Si based intermetallic compounds are sufficiently formed. Also, when the Mn content is 1.50% by mass or less, it is possible to suppress the excessive formation of coarse Al-Mn-Fe-Si based intermetallic compounds. As a result, the ironing formability of the aluminum alloy sheet for beverage can bodies is improved.

[0017] The aluminum alloy sheet for beverage can bodies of the present disclosure contains 1.20% by mass or more and 1.50% by mass or less of Mg. When Mg is solid-solved, it contributes to the improvement of the strength of the aluminum alloy sheet for beverage can bodies. When the Mg content is 1.20% by mass or more, the solid solution amount of Mg can be optimized. When the solid solution amount of Mg is optimal, the material strength of the aluminum alloy sheet for beverage can bodies is improved. Also, when the solid solution amount of Mg after rolling equivalent to ironing on the aluminum alloy sheet for beverage can bodies becomes sufficiently high, the second n value becomes low. As a result, the ironing formability is improved. Rolling equivalent to ironing is rolling in which the equivalent plastic strain ranges from 0.3 to 1.1. When the Mg content is 1.50% by mass or less, it is difficult for the material strength of the aluminum alloy sheet for beverage can bodies to become excessively high. As a result, the ironing formability of the aluminum alloy sheet for beverage can bodies is improved. (1-2) Mechanical properties of the aluminum alloy sheet for beverage can bodies In the aluminum alloy sheet for beverage can body of the present disclosure, the n value in the range of equivalent plastic strain of 0.01 to 0.03 is defined as the first n value. The first n value is 0.049 or more. When the first n value is 0.049 or more, the radial tension in the can bottom chime taper portion increases. When the radial tension in the can bottom chime taper portion increases, tensile deformation is promoted, the material compressed in the circumferential direction extends in the radial direction, and the chime wrinkle resistance is improved.

[0018] When the first n value is less than 0.049, the above effects cannot be sufficiently obtained, and the chime wrinkle resistance deteriorates.

[0019] In the aluminum alloy sheet for beverage can body of the present disclosure, the second n value is 0.063 or less. In DI forming, tensile stress acts on the can side wall portion. The greater the tensile stress, the more likely bursting occurs. When the second n value is 0.063 or less, the tensile stress applied to the can side wall portion in ironing forming decreases, and the ironing formability is improved. When the second n value exceeds 0.063, the tensile stress applied to the can side wall portion in the ironing process increases, and the ironing formability deteriorates.

[0020] 2. Manufacturing method of aluminum alloy sheet for beverage can body The aluminum alloy sheet for beverage can body of the present disclosure is manufactured, for example, by sequentially performing a casting process, a homogenization treatment process, a hot rolling process, and a cold rolling process. The optimum manufacturing conditions in each process in the present disclosure will be described below.

[0021] (2-1) Casting process and homogenization treatment process The ingot of the aluminum alloy contains 0.10 mass% or more and 0.70 mass% of Si, 0.10 mass% or more and 0.80 mass% or less of Fe, 0.10 mass% or more and 0.30 mass% or less of Cu, 0.50 mass% or more and 1.50 mass% or less of Mn, 1.20 mass% or more and 1.50 mass% or less of Mg, and the balance consists of Al and unavoidable impurities. The technical significance of the numerical ranges of the respective components is as described above.

[0022] Al is the main component of the aluminum alloy ingot. The Al contained in this aluminum alloy ingot is, for example, the remainder other than Si, Fe, Cu, Mn, Mg, and inevitable impurities. In the aluminum alloy ingot, the total content of inevitable impurities is preferably 0.5% by mass or less.

[0023] By melting and casting the raw materials in a normal method, an aluminum alloy ingot can be obtained. The casting speed is preferably 10 mm / min or more and 70 mm / min or less. When the casting speed is 10 mm / min or more, crystallization of coarse intermetallic compounds in the ingot can be suppressed. Examples of the intermetallic compounds include Al6Mn and the like. When the casting speed is 70 mm / min or less, the occurrence of ingot cracking is suppressed and the casting yield is improved.

[0024] The homogenization treatment temperature is preferably 550°C or more and 620°C or less. When the homogenization treatment temperature is 550°C or more, fine Al-Mn-Fe-Si-based intermetallic compounds are sufficiently formed and the rolling formability is improved. When the homogenization treatment temperature is 620°C or less, the occurrence of swelling on the surface of the ingot and local melting of the ingot can be suppressed, and a decrease in surface quality can be suppressed. The homogenization treatment time is preferably 1 hour or more. When the homogenization treatment time is 1 hour or more, the homogenization is sufficient, the Mg-Si-based intermetallic compounds crystallized in the casting process are sufficiently redissolved, and the Mg solid solution amount in the slab obtained in the final process becomes high. As a result, a decrease in the strength of the obtained aluminum alloy plate can be suppressed. Hereinafter, the aluminum alloy plate may be abbreviated as a slab.

[0025] (2-2) Hot rolling process Hot rolling is composed of, for example, hot rough rolling and hot finish rolling. The ingot after the homogenization treatment can be directly subjected to the hot rough rolling process without reheating, for example. Hot rough rolling can be performed using, for example, a reversing mill. The hot rough rolling start temperature is preferably 550°C or higher and 600°C or lower. When the hot rough rolling start temperature is 550°C or higher, precipitation of excessive Al-Mn-Si based intermetallic compounds can be suppressed. As a result, the amount of solid solution Mn increases, and a decrease in the strength of the obtained slab can be suppressed. When the hot rough rolling start temperature is 600°C or lower, excessive growth of the formed oxide film can be suppressed, and a decrease in surface quality can be suppressed.

[0026] The time for holding the plate after hot finish rolling at a temperature of 300°C or higher is preferably 10 hours or less. When the holding time is 10 hours or less, the precipitation amount of Mg2Si is suppressed, and the amount of Mg solid solution in the slab increases. Mg2Si is a Mg-Si based intermetallic compound. As a result, the tensile strength is improved. Also, the amount of Mg solid solution becomes high after rolling equivalent to ironing for an aluminum alloy sheet for beverage can bodies. As a result, the second n value becomes low, and the ironing formability is improved. Rolling equivalent to ironing is rolling in which the equivalent plastic strain ranges from 0.3 to 1.1.

[0027] (2-3) Cold rolling process For example, after hot finish rolling, the rolled plate can be subjected to a cold rolling process. In cold rolling, the rolling end temperature of the pass before the final pass is preferably 110°C or higher and 180°C or lower. In cold rolling, the time for holding the plate after the rolling end of the pass before the final pass at a temperature of 100°C or higher is preferably 15 hours or less. When the holding time is 15 hours or less, the precipitation amount of Mg2Si is suppressed, and the amount of Mg solid solution in the slab increases. As a result, the tensile strength is improved. Also, the amount of Mg solid solution becomes high after rolling equivalent to ironing for an aluminum alloy sheet for beverage can bodies. As a result, the second n value becomes low, and the ironing formability is improved. Rolling equivalent to ironing is rolling in which the equivalent plastic strain ranges from 0.3 to 1.1.

[0028] When the rolling finish temperature of the previous pass of the final pass is 180°C or lower, excessive precipitation of Mg-Si-based intermetallic compounds can be suppressed. Therefore, it is possible to suppress an excessive decrease in the Mg solid solution amount after rolling equivalent to ironing for an aluminum alloy sheet for beverage can bodies. As a result, the second n value decreases and the ironing formability improves. Rolling equivalent to ironing is rolling in which the equivalent plastic strain ranges from 0.3 to 1.1.

[0029] In cold rolling, it is more preferable that the rolling finish temperature of the final pass is 140°C or higher and 180°C or lower. When the rolling finish temperature of the final pass is 140°C or higher, recovery of dislocations becomes sufficient, the first n value increases, and the chime wrinkle resistance improves.

[0030] When the rolling finish temperature of the final pass is 180°C or lower, fine precipitation of Mg-Si-based intermetallic compounds can be suppressed. Therefore, it is possible to suppress an excessive decrease in the Mg solid solution amount after rolling equivalent to ironing for an aluminum alloy sheet for beverage can bodies. As a result, the second n value decreases and the ironing formability improves. Rolling equivalent to ironing is rolling in which the equivalent plastic strain ranges from 0.3 to 1.1. Further, when the rolling finish temperature of the final pass is 180°C or lower, excessive recovery of dislocations can be suppressed, and as a result, the material strength improves.

[0031] 3. Examples (3-1) Production of aluminum alloy sheet for beverage can body Aluminum alloy sheets S1 to 8 for beverage can bodies were produced under the production conditions shown in Table 1. All of the aluminum alloy sheets S1 to 8 for beverage can bodies have a composition containing 0.25% by mass of Si, 0.30% by mass of Fe, 0.22% by mass of Cu, 1.19% by mass of Mn, 1.34% by mass of Mg, and the balance being Al and inevitable impurities.

[0032]

Table 1

[0033] (3 - 2) Evaluation method for aluminum alloy sheet for beverage can bodies For each of the aluminum alloy sheets for beverage can bodies of S1 to S8, the following evaluations were performed. (i) Evaluation of tensile strength The aluminum alloy sheet for beverage can bodies was used as a test piece for evaluation. For the test piece, a tensile test was performed in the rolling direction according to JIS Z 2241, and the tensile strength of the test piece was measured. The measurement was performed with 3 specimens. The arithmetic mean value of the measured values of the 3 test pieces was taken as the tensile strength of the aluminum alloy sheet for beverage can bodies. The measurement results of the tensile strength are shown in the column of "Tensile strength" in Table 1.

[0034] (ii) Evaluation of the first n - value Using the measurement results of the tensile strength in (i) above, based on JIS Z 2253, the first n - value was determined in the range where the equivalent plastic strain is 0.01 to 0.03. The first n - value was determined for each of the 3 test pieces, and their arithmetic mean value was taken as the first n - value in the aluminum alloy sheet for beverage can bodies. The measurement results of the first n - value are shown in the column of "n - value ε = 0.01 - 0.03" in Table 1.

[0035] (iii) Evaluation of the second n - value An aluminum alloy sheet for beverage can bodies was used as a blank sheet for evaluation. First, plastic deformation by rolling was applied to the blank sheet so that the equivalent plastic strain reached a predetermined value. The predetermined values of the equivalent plastic strain were 0.3, 0.6, and 1.1. Three blank sheets having the same equivalent plastic strain were prepared respectively. Next, a tensile test was conducted on the blank sheet subjected to plastic deformation, and the yield stress was measured. Next, a double logarithmic graph of the equivalent plastic strain and the yield stress was created. Next, in the created graph, an approximate straight line representing the relationship between the equivalent plastic strain and the yield stress was estimated by linear approximation. Next, the slope of the approximate curve was calculated. Next, a second n value was calculated from the calculated slope. The calculation results of the second n value are shown in the column of "n value ε = 0.3 - 1.1" in Table 1.

[0036] (iv) Evaluation of Mg solid solution amount The Mg solid solution amount was evaluated for each of an aluminum alloy sheet for beverage can bodies that had not been rolled equivalent to ironing and an aluminum alloy sheet for beverage can bodies after being rolled equivalent to ironing. The method for evaluating the Mg solid solution amount is as follows. The conductivity of the aluminum alloy sheet for beverage can bodies was measured with an eddy current conductivity meter, and the specific resistance ρ of the aluminum alloy sheet for beverage can bodies was calculated based on the following formula (1). The measurement frequency was 960 kHz. When the thickness of the sheet to be measured was 0.6 mm or less, a plurality of sheets were stacked to make the thickness 0.6 mm or more for measurement. Formula (1) ρ = 100×ρ Cu ÷EC ρ: Specific resistance (μΩ·cm) ρ Cu : Specific resistance of standard soft copper at 20°C EC: Conductivity (%IACS) ρ Cu The value of is 1.7241 μΩ·cm. A hot-rolled sheet was prepared. The hot-rolled sheet is a sample at the intermediate stage of manufacturing, which is manufactured by the same manufacturing method as the aluminum alloy sheet for beverage can bodies, which is the object of evaluation of the Mg solid solution amount, until hot finish rolling, then cooled without holding, and the subsequent cold rolling and other processes are not carried out. The aluminum alloy sheet for beverage can bodies, which is the object of evaluation of the Mg solid solution amount, is an aluminum alloy sheet for beverage can bodies that has not been rolled equivalent to ironing, or an aluminum alloy sheet for beverage can bodies after being rolled equivalent to ironing. The specific resistance ρ0 of the hot-rolled sheet was measured by the same method as the measurement method of the specific resistance ρ. The unit of the specific resistance ρ0 is μΩ·cm. The specific resistance difference Δρ was calculated by the following formula (2). The unit of the specific resistance difference Δρ is μΩ·cm. Formula (2) Δρ = ρ - ρ0 It was assumed that the calculated specific resistance difference Δρ was due to the precipitation of Mg2Si. Using the constants of the specific resistance of Si and Mg, the Mg solid solution amount difference ΔMg in was calculated by the following formula (3). ΔMg in means the value obtained by subtracting the Mg solid solution amount of the hot-rolled sheet from the Mg solid solution amount of the aluminum alloy sheet for beverage can bodies, which is the object of evaluation of the Mg solid solution amount.

Number

[0037] (v) Chime wrinkle resistance The aluminum alloy sheet for beverage can body was cup-formed and then ironed into the shape of a redrawn can. The blank diameter before cup-forming was 140 mm. The cup diameter after cup-forming was 87 mm. The redrawing diameter of the redrawn can was 66 mm. A 202-diameter DI punch was used for ironing. Using a shape measuring device, the undulation amplitude of the bottom chime taper part of the can was measured over the entire circumference, and the maximum value of the undulation amplitude was obtained. The measurement of the maximum value of the undulation amplitude was carried out with the number N being 5. The arithmetic mean value of the maximum values of the undulation amplitudes in the 5 samples (hereinafter referred to as the average maximum undulation amplitude) was calculated.

[0038] When the average maximum undulation amplitude is 500 μm or less, it is determined that the chime resistance wrinkling property is good, and when the average maximum undulation amplitude exceeds 500 μm, it is determined that the chime resistance wrinkling property is poor. The average maximum undulation amplitude is shown in the column of "Average Maximum Undulation Amplitude" in Table 1. The determination result of the chime resistance wrinkling property is shown in the column of "Chime Resistance Wrinkling Property" in Table 1. "○" means that the chime resistance wrinkling property is good. "×" means that the chime resistance wrinkling property is poor.

[0039] (vi) Ironing formability A disc with a blank diameter of 140 mm was made from an aluminum alloy sheet for the beverage can body. This disc was DI formed to have an inner diameter of 66 mm to make a can. At this time, a punch was used such that the outer diameter became thicker as it approached the can opening from the can bottom, and a severe ironing test was carried out to forcibly cause can breakage during the third ironing. The sheet thickness a at the thinnest part of the can side wall before the third ironing and the sheet thickness b of the can side wall at the time of can breakage were measured. For each of the 10 cans, the sheet thickness a was measured. The average value of the sheet thicknesses a measured for the 10 cans was designated as A. Also, for each of the 10 cans, the sheet thickness b was measured. The average value of the sheet thicknesses b measured for the 10 cans was designated as B. Based on the following formula (5), the limiting ironing rate R was calculated. The limiting ironing rate R is an index of ironing formability.

[0040] Formula (5) R (%) = ((A - B) / A) × 100 It was determined that those with a limit ironing rate R of 50.7% or more were judged to be good, and those with a limit ironing rate of less than 50.7% were judged to be defective. The limit ironing rate R is shown in the column of "limit ironing rate" in Table 1. The determination results of ironing formability are shown in the column of "ironing formability" in Table 1. "○" means that the ironing formability is good. "×" means that the ironing formability is defective. Table 1 shows the results of the comprehensive evaluation. When the chime wrinkle resistance and the ironing formability are good, the result of the comprehensive evaluation is considered good. "○" in Table 1 means that the result of the comprehensive evaluation is good. When the tensile strength, the chime wrinkle resistance, and the ironing formability are good, the result of the comprehensive evaluation is considered particularly good. "◎" in Table 1 means that the result of the comprehensive evaluation is particularly good.

[0041] (3-3) Evaluation Results of Aluminum Alloy Sheets for Beverage Can Bodies In S2 and 4, the tensile strength was 315 MPa or more and 350 MPa or less, the first n value was 0.049 or more, and the second n value was 0.063 or less. As a result, the chime wrinkle resistance and the ironing formability were good.

[0042] In S1, 3, and 7, since the rolling end temperature of the final cold rolling pass was too low, the recovery of dislocations was insufficient. As a result, the first n value decreased and the chime wrinkle resistance was defective.

[0043] In S5, since the rolling end temperature of the final cold rolling pass was higher than the optimum temperature, the precipitation amount of Mg-Si based intermetallic compounds increased and the Mg solid solution amount in the base plate was low. As a result, the tensile strength became relatively lower compared to others.

[0044] In S6, since the holding time at 110 °C or higher after the rolling end of the pass before the final cold rolling pass was too long, the precipitation of Mg-Si based intermetallic compounds increased and the Mg solid solution amount in the plate after rolling equivalent to ironing on the base plate became low. As a result, the second n value increased and the ironing formability was defective. The rolling equivalent to ironing is rolling such that the equivalent plastic strain is in the range of 0.3 to 1.1.

[0045] In S8, since the holding time at 300°C after hot finish rolling was too long, the precipitation amount of the Mg-Si based intermetallic compound increased, and the Mg solid solution amount in the base plate was low. As a result, the tensile strength decreased. In S2, S4, and S5, the chime wrinkle resistance and ironing formability were good. In S2 and S4, the tensile strength, chime wrinkle resistance, and ironing formability were good. 4. Other Embodiments As described above, the embodiments of the present disclosure have been described. However, the present disclosure is not limited to the above-described embodiments and can be implemented with various modifications.

[0046] (1) The functions of one component in each of the above embodiments may be shared by a plurality of components, or the functions of a plurality of components may be exhibited by one component. Also, a part of the configuration of each of the above embodiments may be omitted. Further, at least a part of the configuration of each of the above embodiments may be added to, replaced with, etc. the configuration of other above embodiments.

[0047] (2) In addition to the aluminum alloy sheet for beverage can body described above, the present disclosure can also be realized in various forms such as products having the aluminum alloy sheet for beverage can body as a component, a manufacturing method of the aluminum alloy sheet for beverage can body, a manufacturing method of a beverage can, a manufacturing method of a can body, etc.

Claims

1. An aluminum alloy can body plate, comprising: 0.10% by mass or more and 0.70% by mass or less of Si, 0.10% by mass or more and 0.80% by mass or less of Fe, 0.10% by mass or more and 0.30% by mass or less of Cu, 0.50% by mass or more and 1.50% by mass or less of Mn, 1.20% by mass or more and 1.50% by mass or less of Mg, with the balance being Al and inevitable impurities, wherein the n value in the range of equivalent plastic strain of 0.01 to 0.03 is 0.049 or more, and the n value in the range of equivalent plastic strain of 0.3 to 1.1 is 0.063 or less.

2. An aluminum alloy can body plate, comprising: 0.10% by mass or more and 0.70% by mass or less of Si, 0.10% by mass or more and 0.80% by mass or less of Fe, 0.10% by mass or more and 0.30% by mass or less of Cu, 0.50% by mass or more and 1.50% by mass or less of Mn, 1.20% by mass or more and 1.50% by mass or less of Mg, with the balance being Al and inevitable impurities, wherein the tensile strength is 315 MPa or more and 350 MPa or less, the n value in the range of equivalent plastic strain of 0.01 to 0.03 is 0.049 or more, and the n value in the range of equivalent plastic strain of 0.3 to 1.1 is 0.063 or less.

3. The aluminum alloy can body plate according to Claim 1 or 2, wherein the amount of Mg in solid solution calculated from the difference in specific resistance from the aluminum alloy hot-rolled plate cooled immediately after hot finish rolling is 1.20% by mass or more after rolling in the range of equivalent plastic strain of 0.3 to 1.

1.

4. An aluminum alloy can body plate, comprising: 0.10% by mass or more and 0.70% by mass or less of Si, 0.10% by mass or more and 0.80% by mass or less of Fe, 0.10% by mass or more and 0.30% by mass or less of Cu, 0.50% by mass or more and 1.50% by mass or less of Mn, 1.20% by mass or more and 1.50% by mass or less of Mg, with the balance being Al and inevitable impurities, wherein the n value in the range of equivalent plastic strain of 0.01 to 0.03 is 0.049 or more, the n value in the range of equivalent plastic strain of 0.3 to 1.1 is 0.063 or less, and the amount of Mg in solid solution calculated from the difference in specific resistance from the aluminum alloy hot-rolled plate cooled immediately after hot finish rolling is 1.20% by mass or more after rolling in the range of equivalent plastic strain of 0.3 to 1.

1.

5. It consists of an aluminum alloy containing Si: 0.10% by mass or more and 0.70% by mass or less, Fe: 0.10% by mass or more and 0.80% by mass or less, Cu: 0.10% by mass or more and 0.30% by mass or less, Mn: 0.50% by mass or more and 1.50% by mass or less, Mg: 1.20% by mass or more and 1.50% by mass or less, with the balance being Al and unavoidable impurities. The tensile strength is 315 MPa or more and 350 MPa or less. The n value in the range where the equivalent plastic strain is 0.01 to 0.03 is 0.049 or more. The n value in the range where the equivalent plastic strain is 0.3 to 1.1 is 0.063 or less. The Mg solid solution amount calculated from the resistivity difference from the aluminum alloy hot-rolled sheet cooled immediately after hot finish rolling is 0.96% by mass or more. An aluminum alloy sheet for beverage can body in which the Mg solid solution amount is 1.20% by mass or more after rolling in the range where the equivalent plastic strain is 0.3 to 1.1.

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