JP7704563B2 - Aluminum alloy plate for beverage can body - Google Patents

Description

This disclosure relates to aluminum alloy sheets for beverage can bodies.

2. Description of the Related Art A two-piece can is an example of a beverage can made of an aluminum alloy. The body of the two-piece can is manufactured by subjecting an aluminum alloy plate for a beverage can body to a drawing process, a redrawing process, and an ironing process.
In recent years, the need to reduce the cost of beverage cans has led to a demand for thinner can bodies, thinner blanks, and stronger blanks. However, thinner blanks tend to cause shape defects known as chime wrinkles.

In the redrawing process, if the amount of material flowing into the chime section increases, the diameter is reduced, which increases the circumferential compressive stress, making chime wrinkles more likely to occur. Since chime wrinkles are a buckling phenomenon, the thinner the base plate, the more likely they are to occur. Ironing formability refers to the resistance to breakage and appearance defects during ironing.

Patent Documents 1 to 3 propose a technique for improving chime wrinkles by increasing the work hardening exponent n value of aluminum alloy sheets for beverage can bodies. However, if the work hardening exponent n value is simply increased using the methods described in Patent Documents 1 to 3, the stress in the can side wall during ironing increases. As a result, breaks (i.e., body breaks) are more likely to occur in the can side wall, and ironing formability decreases.

Patent Document 4 proposes a technology that aims to achieve both chime wrinkle resistance and ironing formability by increasing the work hardening exponent n value in aluminum alloy sheets for beverage can bodies while keeping the increase in work hardening rate and tensile strength below a specified value.

JP 2004-300537 A JP 2006-283112 A JP 2006-291326 A WO2016/002226 publication

However, the technology described in Patent Document 4 is insufficient for high-strength aluminum alloy sheets for beverage can bodies, and there is a demand for further improvements in chime wrinkle resistance and ironing formability. One aspect of the present disclosure aims to provide an aluminum alloy sheet for beverage can bodies that has excellent chime wrinkle resistance and ironing formability.

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

The aluminum alloy sheet for beverage can bodies according to one 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 beverage can bodies, which is made 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, and the balance being Al and unavoidable 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 a range of an equivalent plastic strain of 0.01 to 0.03, and an n-value of 0.063 or less in a range of an equivalent plastic strain of 0.3 to 1.1.
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.
Another aspect of the present disclosure is an aluminum alloy sheet for beverage can bodies, comprising 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, wherein an n-value is 0.049 or more when an equivalent plastic strain is in the range of 0.01 to 0.03 and an n-value is 0.063 or less when an equivalent plastic strain is in the range of 0.3 to 1.1, and a Mg solid solution amount calculated from a resistivity difference with respect to an aluminum alloy hot-rolled sheet cooled immediately after hot finish rolling is 1.20% by mass or more after rolling in which an equivalent plastic strain is in the range of 0.3 to 1.1.
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.
Another aspect of the present disclosure is an aluminum alloy comprising: 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; and the balance being Al and unavoidable impurities; and having a tensile strength of 315 MPa or more and 350 MPa or less and an equivalent plastic strain of 0 The aluminum alloy sheet for beverage can bodies has an n-value of 0.049 or more in a range of 0.01 to 0.03, an n-value of 0.063 or less in a range of 0.3 to 1.1 equivalent plastic strain, an amount of dissolved Mg calculated from the difference in resistivity with an aluminum alloy hot-rolled sheet cooled immediately after hot finish rolling is 0.96 mass% or more, and after rolling with an equivalent plastic strain in the range of 0.3 to 1.1, the amount of dissolved Mg is 1.20 mass% or more.
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.

Exemplary embodiments of the present disclosure will now be described.
1. Constitution of aluminum alloy sheet for beverage can body (1-1) Composition of aluminum alloy sheet for beverage can body The aluminum alloy sheet for beverage can body 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 intermetallic compounds, Al-Mg-Cu-Si intermetallic compounds, and Al-Mn-Fe-Si intermetallic compounds. The Al-Mn-Fe-Si intermetallic compounds suppress adhesion of the aluminum alloy sheet for beverage can body to the die mold during ironing. The Al-Mn-Fe-Si intermetallic compounds are α phase. The Al-Mn-Fe-Si intermetallic compounds are extremely hard intermetallic compounds. The Al-Mn-Fe-Si intermetallic compounds have the effect of improving the surface properties of the can body material by solid lubrication action during DI forming.

When the Si content is 0.10% by mass or more, Al-Mn-Fe-Si intermetallic compounds are sufficiently formed. When the Si content is 0.70% by mass or less, the amount of Mg-Si intermetallic compounds, Al-Mg-Cu-Si intermetallic compounds, and Al-Mn-Fe-Si intermetallic compounds can be prevented from excessively increasing. As a result, the amount of Mg dissolved in the aluminum alloy plate for beverage can bodies increases, and the material strength increases. In addition, the amount of Mg dissolved in the aluminum alloy plate for beverage can bodies after rolling equivalent to ironing increases, the second n value decreases, and the ironing formability improves. Rolling equivalent to ironing is rolling in which the equivalent plastic strain is in the range of 0.3 to 1.1. The second n value is the n value when the equivalent plastic strain is in the range of 0.3 to 1.1.

The aluminum alloy plate for beverage can bodies disclosed herein contains 0.10% by mass or more and 0.80% by mass or less of Fe. Fe contributes to the formation of Al-Mn-Fe-Si intermetallic compounds. When the Fe content is 0.10% by mass or more, the Al-Mn-Fe-Si intermetallic compounds are sufficiently formed.

When the Fe content is 0.80 mass% or less, the size and amount of Al-Mn-Fe-Si intermetallic compounds can be prevented from increasing excessively, and cracks during ironing caused by coarse Al-Mn-Fe-Si intermetallic compounds can be prevented. As a result, the ironing formability of the aluminum alloy sheet for beverage can bodies is improved.

The aluminum alloy plate for beverage can bodies disclosed herein contains 0.10% by mass or more and 0.30% by mass or less of Cu. Cu is an element that contributes to the strength of the material.

The Cu content is 0.10% by mass or more. When the Cu content is 0.10% by mass or more, the amount of Cu in solid solution can be optimized. When the amount of Cu in solid solution is optimal, the material strength of the aluminum alloy plate for beverage can bodies is improved. In addition, the Cu content is 0.30% by mass or less. When the Cu content is 0.30% by mass or less, the material strength of the aluminum alloy plate for beverage can bodies is unlikely to be excessively high. As a result, the ironing formability of the aluminum alloy plate for beverage can bodies is improved.

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, which contributes to improving the strength of the aluminum alloy sheet for beverage can bodies and also contributes to the formation of Al-Mn-Fe-Si 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 intermetallic compounds are sufficiently formed. When the Mn content is 1.50% by mass or less, the excessive formation of coarse Al-Mn-Fe-Si intermetallic compounds can be suppressed. As a result, the ironing formability of the aluminum alloy sheet for beverage can bodies is improved.

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 dissolved, it contributes to improving the strength of the aluminum alloy sheet for beverage can bodies. When the Mg content is 1.20% by mass or more, the amount of dissolved Mg can be optimized. When the amount of dissolved Mg is optimized, the material strength of the aluminum alloy sheet for beverage can bodies is improved. Furthermore, when the amount of dissolved Mg is sufficiently high after rolling equivalent to ironing of the aluminum alloy sheet for beverage can bodies, the second n value is reduced. As a result, the ironing formability is improved. Rolling equivalent to ironing is rolling in which the equivalent plastic strain is in the range of 0.3 to 1.1.
When the Mg content is 1.50% by mass or less, the material strength of the aluminum alloy sheet for the beverage can body is unlikely to be excessively high, and as a result, the ironing formability of the aluminum alloy sheet for the beverage can body is improved.
(1-2) Mechanical properties of aluminum alloy sheet for beverage can body In the aluminum alloy sheet for beverage can body of the present disclosure, the n-value in which the equivalent plastic strain is in the range 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 is high. When the radial tension in the can bottom chime taper portion is high, tensile deformation is promoted, and the material compressed in the circumferential direction is stretched in the radial direction, improving chime wrinkle resistance.

If the first n value is less than 0.049, the above effect is not sufficiently achieved and chime wrinkle resistance decreases.

In the aluminum alloy plate for beverage can bodies of the present disclosure, the second n value is 0.063 or less. In DI forming, tensile stress acts on the can side wall. The greater the tensile stress, the more likely it is that the can will break. If the second n value is 0.063 or less, the tensile stress acting on the can side wall during ironing is low, improving ironing formability. If the second n value exceeds 0.063, the tensile stress acting on the can side wall during the ironing process is high, reducing ironing formability.

2. Manufacturing method of aluminum alloy plate for beverage can body The aluminum alloy plate for beverage can body of the present disclosure is manufactured by, for example, sequentially carrying out a casting process, a homogenization process, a hot rolling process, and a cold rolling process. The optimal manufacturing conditions for each process in the present disclosure will be described below.

(2-1) Casting process and homogenization process The aluminum alloy ingot contains 0.10% by mass to 0.70% by mass of Si, 0.10% by mass to 0.80% by mass of Fe, 0.10% by mass to 0.30% by mass of Cu, 0.50% by mass to 1.50% by mass of Mn, and 1.20% by mass to 1.50% by mass of Mg, with the remainder being Al and unavoidable impurities. The technical significance of the numerical range of each component is as described above.

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

An aluminum alloy ingot can be obtained by melting and casting the raw materials in a normal manner. 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, it is possible to suppress the crystallization of coarse intermetallic compounds in the ingot. Examples of intermetallic compounds include Al ₆ Mn. When the casting speed is 70 mm/min or less, the occurrence of cracks in the ingot is suppressed, and the casting yield is improved.

The homogenization temperature is preferably 550° C. or higher and 620° C. or lower. When the homogenization temperature is 550° C. or higher, fine Al-Mn-Fe-Si intermetallic compounds are sufficiently formed, improving ironing formability. When the homogenization temperature is 620° C. or lower, the occurrence of blistering on the surface of the ingot and local melting of the ingot can be suppressed, and deterioration of 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, homogenization is sufficiently performed, the Mg-Si intermetallic compounds crystallized in the casting process are sufficiently re-dissolved, and the amount of dissolved Mg in the blank obtained in the final process is increased. As a result, the decrease in strength of the obtained aluminum alloy sheet can be suppressed. Hereinafter, the aluminum alloy sheet may be abbreviated as blank.

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

It is preferable that the time for which the plate after hot finish rolling is held at a temperature of 300°C or higher is 10 hours or less. When the holding time is 10 hours or less, the amount of Mg ₂ Si precipitated is suppressed, and the amount of Mg in solid solution in the raw plate increases. Mg ₂ Si is an Mg-Si intermetallic compound. As a result, the tensile strength is improved. In addition, the amount of Mg in solid solution after rolling equivalent to ironing of the aluminum alloy plate for beverage can bodies increases. As a result, the second n value is reduced, and ironing formability is improved. Rolling equivalent to ironing is rolling in which the equivalent plastic strain is in the range of 0.3 to 1.1.

(2-3) Cold rolling process For example, after hot finish rolling, the rolled sheet 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 more and 180°C or less. In cold rolling, the time for which the sheet after the rolling of the pass before the final pass is held at a temperature of 100°C or more is preferably 15 hours or less. When the holding time is 15 hours or less, the amount of precipitation of Mg ₂ Si is suppressed, and the amount of solid solution of Mg in the blank increases. As a result, the tensile strength is improved. In addition, the amount of solid solution of Mg after rolling equivalent to ironing of the aluminum alloy sheet for beverage can bodies increases. As a result, the second n value is lowered, and the ironing formability is improved. Rolling equivalent to ironing is rolling in which the equivalent plastic strain is in the range of 0.3 to 1.1.

When the rolling end temperature of the pass before the final pass is 180°C or lower, excessive precipitation of Mg-Si intermetallic compounds can be suppressed. This can prevent the amount of Mg in solid solution from decreasing excessively after rolling equivalent to ironing of the aluminum alloy sheet for beverage can bodies. As a result, the second n value is lowered and ironing formability is improved. Rolling equivalent to ironing is rolling in which the equivalent plastic strain is in the range of 0.3 to 1.1.

In cold rolling, it is more preferable that the rolling end temperature of the final pass is 140°C or higher and 180°C or lower. If the rolling end temperature of the final pass is 140°C or higher, dislocation recovery is sufficient, the first n value is high, and chime wrinkle resistance is improved.

When the rolling end temperature of the final pass is 180°C or lower, fine precipitation of Mg-Si intermetallic compounds can be suppressed. This can prevent the amount of Mg in solid solution from being excessively reduced after rolling equivalent to ironing of the aluminum alloy sheet for beverage can bodies. As a result, the second n value is lowered, and ironing formability is improved. Rolling equivalent to ironing is rolling in which the equivalent plastic strain is in the range of 0.3 to 1.1. In addition, when the rolling end temperature of the final pass is 180°C or lower, excessive recovery of dislocations can be suppressed, and as a result, material strength is improved.

3. Examples (3-1) Production of aluminum alloy plate for beverage can body Aluminum alloy plates S1 to S8 for beverage can body were produced under the production conditions shown in Table 1. Each of the aluminum alloy plates S1 to S8 for beverage can body has a composition containing 0.25 mass% Si, 0.30 mass% Fe, 0.22 mass% Cu, 1.19 mass% Mn, 1.34 mass% Mg, with the balance being Al and unavoidable impurities.

以下の方法で飲料缶胴用アルミニウム合金板を製造する点では、Ｓ１～８の全てにおいて共通する。まず、アルミニウム合金の鋳塊を半連続鋳造法により鋳造した。次に、鋳塊の表面を面削した後に、鋳塊に対し、６００℃で３時間の均質化処理工程を行った。次に、鋳塊に対し、シングルリバース式の熱間粗圧延工程を行い、熱間圧延板を得た。次に、この熱間圧延板に対し、４スタンドのタンデム式の熱間仕上げ圧延工程を行い、熱間圧延板を得た。熱延開始温度は５８０℃であった。最後に、熱間圧延板に対し、冷間圧延工程を行い、飲料缶胴用アルミニウム合金板を得た。
Ｓ１～Ｓ８の製造におけるその他の条件は表１に示すとおりである。

All of S1 to S8 have in common that an aluminum alloy plate for beverage can bodies is manufactured by the following method. First, an aluminum alloy ingot was cast by a semi-continuous casting method. Next, after the surface of the ingot was chamfered, the ingot was subjected to a homogenization treatment process at 600°C for 3 hours. Next, the ingot was subjected to a single reverse hot rough rolling process to obtain a hot rolled plate. Next, this hot rolled plate was subjected to a four-stand tandem hot finish rolling process to obtain a hot rolled plate. The hot rolling start temperature was 580°C. Finally, the hot rolled plate was subjected to a cold rolling process to obtain an aluminum alloy plate for beverage can bodies.
Other conditions for the production of S1 to S8 are as shown in Table 1.

(3-2) Evaluation method for aluminum alloy sheet for beverage can body The following evaluations were carried out for each of the aluminum alloy sheets for beverage can bodies S1 to S8.
(i) Evaluation of tensile strength The aluminum alloy plate for beverage can bodies was used as a raw plate for evaluation. A tensile test was performed on the raw plate in the rolling direction according to JIS Z 2241 to measure the tensile strength of the raw plate. The measurement was performed with an N number of 3. The arithmetic average value of the measured values for the three raw plates was taken as the tensile strength of the aluminum alloy plate for beverage can bodies. The measurement results of the tensile strength are shown in the column of "tensile strength" in Table 1.

(ii) Evaluation of the first n value Using the measurement results of the tensile strength in (i) above, the first n value was determined in the range of equivalent plastic strain of 0.01 to 0.03 based on JIS Z 2253. The first n value was determined for each of the three blanks, and their arithmetic average value was taken as the first n value for 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.

(iii) Evaluation of the second n value Aluminum alloy plates for beverage can bodies were used as blanks for evaluation. First, the blanks were subjected to plastic deformation by rolling so that the equivalent plastic strains were set to predetermined values. The predetermined values of the equivalent plastic strains were 0.3, 0.6, and 1.1. Three blanks each having the same equivalent plastic strain were prepared.
Next, a tensile test was performed on the plastically deformed blank to measure the yield stress. Next, a log-log graph of the equivalent plastic strain and the yield stress was created. Next, in the created graph, an approximation line representing the relationship between the equivalent plastic strain and the yield stress was estimated by linear approximation. Next, the slope of the approximation curve was calculated. Next, the second n value was calculated from the calculated slope. The calculation result of the second n value is shown in the column of "n value ε = 0.3-1.1" in Table 1.

式（３）における各項の意味は以下のとおりである。
ΔＭｇ_ｉｎ：熱延板とのＭｇ固溶量差（質量％）
Ｘ_Ｍｇｉｎ：固溶体中のＭｇの比抵抗の定数
Ｘ_{Ｍｇｏｕｔ}：固溶体外のＭｇの比抵抗の定数
Ｘ_Ｓｉｉｎ：固溶体中のＳｉの比抵抗の定数
Ｘ_{Ｓｉｏｕｔ}：固溶体外のＳｉの比抵抗の定数
Ｙ_{Ｍｇ２Ｓｉ}：Ｍｇ_２ＳｉにおけるＳｉに対するＭｇの質量比
Ｘ_Ｍｇｉｎの値は０．５４μΩ・ｃｍ／質量％である。Ｘ_{Ｍｇｏｕｔ}の値は０．２２μΩ・ｃｍ／質量％である。Ｘ_Ｓｉｉｎの値は１．０２μΩ・ｃｍ／質量％である。Ｘ_{Ｓｉｏｕｔ}の値は０．０８８μΩ・ｃｍ／質量％である。Ｙ_{Ｍｇ２Ｓｉ}の値は１．７３である。
Ｍｇ固溶量差ΔＭｇ_ｉｎと、熱延板のＭｇ固溶量Ｍｇ_ｉｎ０とを用いて、以下の式（４）により、Ｍｇ固溶量Ｍｇ_ｉｎを算出した。
式（４） Ｍｇ_ｉｎ＝Ｍｇ_ｉｎ０＋ΔＭｇ_ｉｎ
熱延板のＭｇ固溶量Ｍｇ_ｉｎ０は、３５０℃における平衡固溶量であると仮定した。熱延板のＭｇ固溶量Ｍｇ_ｉｎ０は、ＪＭａｔＰｒｏ－ｖ１０．１により計算した。ＪＭａｔＰｒｏ－ｖ１０．１は、Sente Software社製の金属物性値計算ソフトウェアである。
計算の際、ＭＡＴＥＲＩＡＬＳ ＴＹＰＥＳとしてＡｌｕｍｉｎｕｍ ａｌｌｏｙを選択し、熱延板に含まれる元素のうちＣｕ、Ｆｅ、Ｍｇ、Ｍｎ、Ｓｉ、Ｃｒ、Ｔｉ、Ｚｎの質量分率（質量％）を入力した。Ｃｕ、Ｆｅ、Ｍｇ、Ｍｎ、Ｓｉの質量分率（質量％）が小数点以下２桁となり、Ｃｒ、Ｔｉ、Ｚｎの質量分率（質量％）が小数点以下３桁となるように四捨五入した。
しごき成形相当の圧延をしていない飲料缶胴用アルミニウム合金板のＭｇ固溶量Ｍｇ_ｉｎを、表１における「Ｍｇ固溶量 ε＝０」の列に示す。しごき成形相当の圧延をした後の飲料缶胴用アルミニウム合金板のＭｇ固溶量Ｍｇ_ｉｎを、表１における「Ｍｇ固溶量 ε＝１．１」の列に示す。 (iv) Evaluation of the amount of Mg in solid solution The amount of Mg in solid solution was evaluated for each of the aluminum alloy sheets for beverage can bodies that had not been rolled to a degree equivalent to ironing and the aluminum alloy sheets for beverage can bodies that had been rolled to a degree equivalent to ironing. The method for evaluating the amount of Mg in solid solution was as follows.
The electrical conductivity of the aluminum alloy plate for the body of a beverage can was measured by an eddy current type electrical conductivity meter, and the resistivity ρ of the aluminum alloy plate for the body of a beverage can was calculated based on the following formula (1): The measurement frequency was 960 kHz, and when the thickness of the plate to be measured was 0.6 mm or less, multiple plates were stacked to make the thickness 0.6 mm or more.
Formula (1) ρ=100×ρ _Cu ÷EC
ρ: Specific resistance (μΩ・cm)
ρ _Cu : resistivity of standard soft copper at 20°C EC: electrical conductivity (% IACS)
The value of ρ _Cu is 1.7241 μΩ·cm.
A hot-rolled sheet was prepared. The hot-rolled sheet is a sample in the intermediate stage of production, which is produced by the same production method as the aluminum alloy sheet for beverage can bodies to be evaluated for the amount of Mg solid solution up to hot finish rolling, and then cooled without holding, and no subsequent steps such as cold rolling are carried out. The aluminum alloy sheet for beverage can bodies to be evaluated for the amount of Mg solid solution is an aluminum alloy sheet for beverage can bodies that has not been rolled to a degree equivalent to ironing, or an aluminum alloy sheet for beverage can bodies that has been rolled to a degree equivalent to ironing. The resistivity ρ ₀ of the hot-rolled sheet was measured by the same method as the method for measuring the resistivity ρ. The unit of resistivity ρ ₀ is μΩ·cm.
The resistivity difference Δρ was calculated by the following formula (2): The resistivity difference Δρ is expressed in μΩ·cm.
Equation (2) Δρ=ρ−ρ ₀
It was assumed that the calculated resistivity difference Δρ was due to the precipitation of Mg ₂ Si. Using the resistivity constants of Si and Mg, the Mg solid solution amount difference ΔMg _in was calculated by the following formula (3). ΔMg _in means a 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 subject of evaluation of the Mg solid solution amount.

The meaning of each term in formula (3) is as follows:
ΔMg _in : Difference in Mg solid solution amount from hot-rolled sheet (mass%)
X _Mgin : constant of resistivity of Mg in solid solution X _Mgout : constant of resistivity of Mg outside solid solution X _Siin : constant of resistivity of Si in solid solution X _Siout : constant of resistivity of Si outside solid solution Y _Mg2Si : mass ratio of Mg to Si in Mg ₂ Si The value of X _Mgin is 0.54 μΩ·cm/mass%. The value of X _Mgout is 0.22 μΩ·cm/mass%. The value of _{X Siin} is 1.02 μΩ·cm/mass%. The value of X _Siout is 0.088 μΩ·cm/mass%. The value of _{Y Mg2Si} is 1.73.
The amount of solute Mg, Mg _in , was calculated by the following formula (4) using the difference in the amount of solute Mg _, ΔMg in, and the amount of solute Mg, Mg _in0, of the hot-rolled sheet.
Formula (4) Mg _in =Mg _in0 +ΔMg _in
The amount of Mg in the hot-rolled sheet, Mg _in0 , was assumed to be the equilibrium amount at 350° C. The amount of Mg in the hot-rolled sheet, Mg _in0 , was calculated using JMatPro-v10.1. JMatPro-v10.1 is metal property calculation software manufactured by Sente Software.
In the calculation, aluminum alloy was selected as MATERIALS TYPES, and the mass fractions (mass%) of Cu, Fe, Mg, Mn, Si, Cr, Ti, and Zn among the elements contained in the hot-rolled sheet were input. The mass fractions (mass%) of Cu, Fe, Mg, Mn, and Si were rounded off to two decimal places, and the mass fractions (mass%) of Cr, Ti, and Zn were rounded off to three decimal places.
The amount of Mg in solid solution, Mg _in , of an aluminum alloy sheet for a beverage can body that has not been subjected to rolling equivalent to ironing is shown in the column of "amount of Mg in solid solution, ε=0" in Table 1. The amount of Mg in solid solution, Mg _in, of an aluminum alloy sheet for a beverage can body that has been subjected to rolling equivalent to ironing is shown in the column of "amount of Mg in solid solution, ε=1.1" in Table 1.

(v) Chime wrinkle resistance An aluminum alloy plate for a beverage can body was formed into a cup shape, and then drawn into a shape of a redrawn can. The blank diameter before the cup forming was 140 mm. The cup diameter after the cup forming was 87 mm. The redrawn diameter of the redrawn can was 66 mm. A 202 diameter DI punch was used for the drawing.
The undulation amplitude of the chime taper portion of the can bottom was measured over the entire circumference using a shape measuring device, and the maximum undulation amplitude was determined. The measurement of the maximum undulation amplitude was performed with an N number of 5 samples. The arithmetic mean value of the maximum undulation amplitude of the five samples (hereinafter referred to as the average maximum undulation amplitude) was calculated.

If the average maximum amplitude of undulation was 500 μm or less, the chime wrinkle resistance was judged to be good, and if the average maximum amplitude of undulation was more than 500 μm, the chime wrinkle resistance was judged to be poor. The average maximum amplitude of undulation is shown in the "average maximum amplitude of undulation" column in Table 1. The judgment results of chime wrinkle resistance are shown in the "chime wrinkle resistance" column in Table 1. "○" means that the chime wrinkle resistance is good. "×" means that the chime wrinkle resistance is poor.

(vi) Ironing formability A blank disk with a diameter of 140 mm was prepared from an aluminum alloy plate for beverage can bodies. This disk was DI-formed to an inner diameter of 66 mm to prepare a can. A punch with an outer diameter that increases from the bottom of the can toward the can opening was used to perform a severe ironing test in which the can was forcibly opened at the third ironing. The thickness a of the thinnest part of the can side wall before the third ironing and the thickness b of the can side wall when the can was opened were measured.
The plate thickness a was measured for each of the 10 cans. The average value of the plate thickness a measured for the 10 cans was designated as A. Furthermore, the plate thickness b was measured for each of the 10 cans. The average value of the plate thickness b measured for the 10 cans was designated as B.
The critical ironing ratio R was calculated based on the following formula (5). The critical ironing ratio R is an index of ironing formability.

Formula (5) R (%) = ((A - B) / A) x 100
A critical ironing rate R of 50.7% or more was judged to be good, and a critical ironing rate of less than 50.7% was judged to be bad. The critical ironing rate R is shown in the "critical ironing rate" column in Table 1. The judgment results of the ironing formability are shown in the "ironing formability" column in Table 1. "○" means that the ironing formability is good. "×" means that the ironing formability is poor.
The results of the overall evaluation are shown in Table 1. When the chime wrinkle resistance and ironing formability were good, the overall evaluation result was deemed to be good. "○" in Table 1 means that the overall evaluation result was good. When the tensile strength, chime wrinkle resistance, and ironing formability were good, the overall evaluation result was deemed to be particularly good. "◎" in Table 1 means that the overall evaluation result was particularly good.

(3-3) Evaluation results of aluminum alloy sheets for beverage can bodies In S2 and S4, 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 ironing formability were good.

In S1, 3, and 7, the rolling end temperature of the final cold rolling pass was too low, so dislocation recovery was insufficient. As a result, the first n value was low and chime wrinkle resistance was poor.

In S5, the rolling end temperature of the final cold rolling pass was higher than the optimal temperature, which increased the amount of precipitation of Mg-Si intermetallic compounds and reduced the amount of Mg in solid solution in the blank. As a result, the tensile strength was relatively low compared to the others.

In S6, the holding time at 110°C or higher after the end of the pass before the final cold rolling pass was too long, which increased the precipitation of Mg-Si intermetallic compounds and reduced the amount of Mg in solid solution in the sheet after rolling equivalent to ironing of the blank. As a result, the second n value was high and the ironing formability was poor. Rolling equivalent to ironing is rolling in which the equivalent plastic strain is in the range of 0.3 to 1.1.

In S8, the holding time at 300°C after hot finish rolling was too long, so the amount of precipitated Mg-Si intermetallic compounds increased and the amount of Mg in solid solution in the blank was low, resulting in low tensile strength.
S2, S4, and S5 were good in chime wrinkle resistance and iron formability. S2 and S4 were good in tensile strength, chime wrinkle resistance, and iron formability.
4. Other Embodiments Although the embodiments of the present disclosure have been described above, the present disclosure is not limited to the above-described embodiments and can be implemented in various modifications.

(1) The function of one component in each of the above embodiments may be shared among multiple components, or the function of multiple components may be performed by one component. Also, part of the configuration of each of the above embodiments may be omitted. Also, at least part of the configuration of each of the above embodiments may be added to or substituted for the configuration of another of the above embodiments.

(2) In addition to the aluminum alloy plate for beverage can bodies described above, the present disclosure can also be realized in various forms, such as products that include the aluminum alloy plate for beverage can bodies as a component, a method for manufacturing the aluminum alloy plate for beverage can bodies, a method for manufacturing beverage cans, and a method for manufacturing can bodies.

Claims (5)

an aluminum alloy containing 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;
The n value is 0.049 or more in the range of equivalent plastic strain of 0.01 to 0.03,
An aluminum alloy sheet for beverage can bodies, having an n-value of 0.063 or less in the range of equivalent plastic strain of 0.3 to 1.1. an aluminum alloy containing 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;
The tensile strength is 315 MPa or more and 350 MPa or less,
The n value is 0.049 or more in the range of equivalent plastic strain of 0.01 to 0.03,
An aluminum alloy sheet for beverage can bodies, having 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 beverage can bodies according to claim 1 or 2,
An aluminum alloy sheet for beverage can bodies, in which the amount of dissolved magnesium calculated from the difference in resistivity between the aluminum alloy sheet and a hot-rolled sheet cooled immediately after hot finish rolling is 1.20 mass % or more after rolling with an equivalent plastic strain in the range of 0.3 to 1.1 . an aluminum alloy containing 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;
The n value is 0.049 or more in the range of equivalent plastic strain of 0.01 to 0.03,
The n value is 0.063 or less in the range of equivalent plastic strain of 0.3 to 1.1,
An aluminum alloy sheet for beverage can bodies, in which the amount of dissolved magnesium calculated from the difference in resistivity between the aluminum alloy sheet and a hot-rolled sheet cooled immediately after hot finish rolling is 1.20 mass % or more after rolling with an equivalent plastic strain in the range of 0.3 to 1.1. an aluminum alloy containing 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;
The tensile strength is 315 MPa or more and 350 MPa or less,
The n value is 0.049 or more in the range of equivalent plastic strain of 0.01 to 0.03,
The n value is 0.063 or less in the range of equivalent plastic strain of 0.3 to 1.1,
The amount of Mg in solid solution calculated from the resistivity difference with respect to an aluminum alloy hot-rolled sheet cooled immediately after hot finish rolling is 0.96 mass% or more,
The aluminum alloy sheet for beverage can bodies has a solute amount of Mg of 1.20 mass% or more after rolling to an equivalent plastic strain in the range of 0.3 to 1.1.