JPH0472044A - Manufacture of aluminum alloy for packaging container having high strength and low orientation property - Google Patents

Abstract

PURPOSE:To obtain an aluminum alloy for a packaging container by specifying the amounts of Mn, Mg and Cu as main alloy elements and manufacturing conditions in an Al alloy having a specified compsn. CONSTITUTION:This Al alloy is formed by subjecting the ingot of an allay contg., as essential components, by weight, 0.5 to 1.5% Mn, 0.5 to 3% Mg and 0.5 to 3% Cu, furthermore contg. one or more kinds among <=0.7% Fe, <=0.6%. Si, 0.4% Zn, <=0.3% Cr and <=0.05% Ti and the balance A to homogenizing heat treatment at 500 to 600 deg.C and hot rolling at 270 to 600 deg.C and thereafter combinedly executing process annealing at 350 to 550 deg.C and cold rolling at 30 to 70% cold rolling ratio.

Description

[Detailed description of the invention]

(Industrial Application Field) The present invention relates to the production of an aluminum alloy for packaging containers,
Mainly DI (Drawn & I roned)
) This relates to a method for manufacturing aluminum alloy plate material for handling and processing suitable for cans. (Prior art and problems to be solved) Aluminum cans used for beverage cans such as beer and carbonated drinks, food cans, etc. are processed by DI processing and DRD (Drawn & Red).
cans obtained by the former processing method are called DI cans, and those obtained by the latter processing method are called DRD cans. DI cans are usually cans with a can bottom thickness of 0.30-0.35 m+a, and the typical manufacturing process is as follows:
The process consists of drawing (usually twice) → handling (usually three times) → inner surface painting → outer surface painting → necking → flanging. At this time, it is particularly important that the aluminum alloy plate used as the raw material has the following characteristics (1) to (4). ■Material strength to obtain the required can bottom strength. ■It has excellent seizure resistance with the mold during handling. In other words, the material itself has a self-lubricating effect. ■The occurrence of ears after DI processing is small. In other words, the directionality is small. ■Excellent flange workability at the tightening part with the end. Regarding the above ■, the can strength (= pressure resistance) P is as follows (1)
It is expressed by the formula. P = to σt1・2 ・・・・・・(1) (Here,
(σ: material strength (yield strength), t: plate thickness, k: shape factor determined by the shape of the can bottom) Therefore, there are the following three methods to increase the withstand pressure of one can. ■Use strong materials. ■Develop a can bottom shape with high pressure resistance. ■Increase the thickness of the material. Recently, there has been a strong demand for thinner materials, and there has been a strong demand for the development of high pressure-resistant can bottom shapes and the development of material strength. In this respect, the 3004 alloy material (An-1, 2Mn-1, 1
Mg) (standard yield strength 24-26 kgf/m112) is also disclosed in Patent No. 1519469 (Special Publication No. 61-746).
No. 5) "Bake-hardened aluminum alloy hard plate for canvas bodies and its manufacturing method", high-strength materials (yield strength 28-29 kg/am") has been developed and is widely used as a thinner material. However, in the future, there will be demands for even thinner walls both overseas and domestically, and ultra-high It has become necessary to develop a high-strength material.The present invention was made in response to these demands, and the present invention has been made to meet these demands. It is an object of the present invention to provide a method for manufacturing an aluminum alloy for packaging containers having As a result of intensive research into manufacturing conditions, etc., we adjusted the chemical composition based on the addition amount of Mn, Mg, and Cu as the main alloying elements, and also applied homogenization heat treatment, hot rolling, cold rolling, and intermediate annealing. By optimizing the conditions,
It was determined that a canvas material with high strength and low selvage ratio could be obtained. That is, in the present invention, Mn: 0.5 to 1.5%, Mg:
Contains 0.5-3% and Cu: 0.5-3% as essential components, and further contains Fe: 0.7% or less, Si: 0.6% or less, Zn: 0.4% or less, Cr: 0 .3% or less and Ti:
5% to an aluminum alloy ingot containing one or more of 0.05% or less, with the remainder consisting of An and impurities.
Soaking heat treatment at 00-600℃, 270-600℃
Aluminum for packaging containers having high strength and low directionality, characterized in that it is hot rolled at ℃ and then subjected to a combination of intermediate annealing at 350 to 550 ℃ and cold rolling at a cold rolling rate of 30 to 70%. The gist of this paper is the method for producing alloys. The present invention will be explained in more detail below. (Function) First, the reason for limiting the chemical components in the present invention will be explained. Mn: Mn imparts strength through solid solution strengthening, forms an intermetallic compound (Mn, Fe) A Q with An, imparts a fine grain structure, and has a mold cleaning effect due to the intermetallic compound during handling and processing. It is the most important element for providing anti-seize effect. However, if it is less than 0.5%, sufficient strength and anti-seizure effect cannot be obtained. Moreover, Mn is 1.
If it exceeds 5%, a texture will develop, the selvage rate will increase, and cracks will occur due to stress concentration around the intermetallic compound during flange processing, which will greatly impair can manufacturing yield. Therefore, the amount of Mn is set in the range of 0.5 to 1.5%. Mg: Mg is an element that imparts strength through solid solution strengthening.
If it is less than 0.5%, sufficient strength cannot be obtained, and if it exceeds 3%, SS marks etc. may occur during cup molding, resulting in D
It becomes a defect when the I can is produced. In addition, work hardening during cold rolling becomes abnormally large, greatly impairing the formability of the material. Therefore, the amount of Mg is 0.5
-3% range. Therefore, the amount of Fe is set to 0.7% or less. Cu: Cu is an element that imparts strength through solid solution strengthening and precipitation hardening, but if it is less than 0.5%, sufficient strength cannot be obtained, and if it is contained in more than 3%, corrosion resistance will be greatly impaired and the strength will be too high. This makes it difficult to adjust the strength. therefore,
The amount of Cu is in the range of 0.5 to 3%, and is preferably 0.5% to 3%.
, in the range of 6-3%. Although the above elements are contained as essential components, in the present invention, one or more of the following elements Fe, Si, Zn, Cr, and Ti are contained in appropriate amounts. Fe: Fe is effective in imparting strength, and (Fe, Mn)
It is treated as a crystallized product of Si□An1□ and has the effect of preventing seizure during processing.
) An is an element that forms an intermetallic compound. However, if it exceeds 0.7%, coarse intermetallic compounds (M
n, Fe) forms An6 and impairs moldability. Si: Si is an element that provides an anti-seizure effect during molding as a crystallized product of the aforementioned (Mn, Fe)An6, but at 0.6%
If it exceeds this amount, coarse crystallized substances will be generated and the moldability will be impaired. Therefore, the amount of Si is set to 0°6% or less. Zn: Zn is an element that not only provides strength but also makes crystallized substances finer. However, if it exceeds 0.5%, corrosion resistance deteriorates, so the amount of Zn is set to 0.4% or less. Cr, Ti: Both Cr-Ti are elements added to finely control the structure, but if added in excess of 0.3% and 0.05%, respectively, coarse intermetallic compounds will occur. , the amount of Cr is 0.3% or less, and the amount of Ti is 0.0%, since it impairs the formability.
5% or less. Next, the manufacturing method of the present invention will be explained. An aluminum alloy having the above-mentioned chemical components is melted and cast into an ingot using a conventional method. The ingot is formed by, for example, a DC casting method. The obtained ingot needs to be subjected to homogenization heat treatment at a temperature of 500 to 600°C. The purpose of this homogenization heat treatment is to homogenize microsegregation and form desired intermetallic compounds. However, if it is less than 500°C, a sufficient homogenizing heat treatment effect and the desired intermetallic compound (Mn, Fe) AI2G cannot be formed, and if it exceeds 600°C, there is a risk of eutectic melting, which is not preferable. Note that the heating time is not particularly limited, but a range of 3 to 24 hours within the above temperature range is desirable. Next, after being taken out of the furnace, hot rolling is performed at a temperature of 600 to 270°C to obtain a hot rolled plate of approximately 2 to 5 μm. At this time, if rolling is carried out at a temperature below 270° C., cold strain will be introduced and a sufficiently uniform hot unrecrystallized structure will not be obtained. Note that the above temperature of 600°C is a value defined by the upper limit of the homogenization heat treatment temperature of 600°C. Thereafter, intermediate annealing is performed at a temperature of 350 to 550'C to obtain a soft material. The intermediate annealing temperature is set in the range of 350 to 550°C, since a sufficiently soft material cannot be obtained if it is less than 350°C, and abnormally coarse grains occur if it exceeds 550°C. The heating time for intermediate annealing is determined as appropriate, but it is 350 to 4
In the temperature range of 00°C, 2 to 4 hours are required, and in the case of high-temperature treatment using a continuous annealing furnace, for example, 0.5 hours at 500°C.
It is best to aim for a heating time of ~10 seconds. In some cases, intermediate rolling may be performed to adjust the finish rolling rate prior to intermediate annealing. Finally, the obtained material is subjected to cold rolling (finish rolling) to form a hard material. In this case, sufficient strength cannot be obtained with a cold rolling reduction of less than 30%. On the other hand, at a cold rolling rate of more than 70%, cold rolling develops a texture in which crystal grains are oriented in a preferential direction, resulting in directional properties of the material, resulting in selvage of approximately 3% or more when forming into cans. This makes it necessary to increase the amount of trimming after molding, which significantly reduces product value, and tends to cause problems such as cracking during can manufacturing due to work hardening of the material due to excessive cold working. Therefore, the cold rolling rate is set in the range of 30 to 70%. Through the above steps, a plate material having a thickness of about 0.3 to Q and 4 mm+ is obtained. This plate material is formed into a can of desired size and shape through steps such as DI processing, baking, painting, necking, and flanging using conventional methods. (Example) Next, an example of the present invention will be shown. An aluminum alloy ingot with a thickness of 600m+* having the chemical composition shown in Table 1 was melted using the DC casting method, and
Homogenized heat treatment at 75℃ x 6hrs, 550~300℃
Hot rolling was carried out at a temperature of "C" to obtain a hot coil with a thickness of 3 m + w. Next, it was intermediate rolled to a thickness of 0.6 "C) + m, and then rolled to a temperature of 500" C.
Intermediate annealing was performed for 3 seconds, and finish rolling was performed to form a hard plate with a thickness of 0.30 mm (finish cold rolling rate: 50%). The mechanical properties of the obtained material as manufactured and after it has been subjected to a treatment equivalent to painting heat treatment (200'C I did it. The results are also listed in Table 1. Note that the selvage ratio was determined using a punch diameter of 40 mmφ and a drawing ratio of 40%. Further, the punch diameter was set to 33φ at the limit drawing rate. Flange workability is 0 (good), 0. - Rated as (Poor). From Table 1, all the aluminum alloy plates of the present invention examples are:
It can be seen that it has high strength, excellent selvage rate, drawing workability, and flange workability. On the other hand, the comparative example lacks strength and is inferior in selvage ratio, moldability, etc. Example 2 A hard plate having a final plate thickness of 0.30 mm was manufactured using the aluminum alloy &1 in Table 1 through the manufacturing process under various conditions shown in Table 2. The material properties of the obtained material were evaluated in the same manner as in Example 1. The results are also listed in Table 2. From Table 2, all of the aluminum alloy plates of the present invention examples are:
It can be seen that it has high strength, excellent selvage rate, drawing workability, and flange workability. On the other hand, the comparative example lacks strength and is inferior in selvage ratio, moldability, etc.

[Left below]

(Effects of the Invention) As detailed above, according to the present invention, manufacturing conditions are regulated and applied to aluminum alloys with specific chemical components, so that hard aluminum alloys for packaging with high strength and low directionality can be produced. Boards can be manufactured. It is particularly suitable for manufacturing DI cans, and has a very large effect in reducing the thickness of DI cans. Patent applicant Hisashi Nakamura, patent attorney representing Kobe Steel, Ltd.

Claims (1)

[Claims] In weight% (hereinafter the same), Mn: 0.5 to 1.5%, M
Contains g: 0.5-3% and Cu: 0.5-3% as essential components, further Fe: 0.7% or less, Si: 0.6%
Below, Zn: 0.4% or less, Cr: 0.3% or less, and T
i: An aluminum alloy ingot containing one or more of 0.05% or less, with the remainder consisting of An and impurities, is subjected to soaking heat treatment at 500 to 600 °C to produce 270 to 6
For packaging containers having high strength and low directionality, which is characterized by hot rolling at 00°C, followed by a combination of intermediate annealing at 350-550°C and cold rolling at a cold rolling rate of 30-70%. Method of manufacturing aluminum alloy.