JPH0361350A - Manufacture of aluminum alloy for drawing having high strength and low directional property - Google Patents

Abstract

PURPOSE:To obtain the Al alloy for drawing free from surface strain figure, in an Al alloy ingot having specified chemical components, by regulatively applying each condition in homogenizing heat treatment and hot rolling and obtaining a structure contg. intermetallic compounds of prescribed size and quantity. CONSTITUTION:An Al alloy ingot contg., as essential components, by weight, 0.8 to 1.5% Mg, 0.30 to 0.5% Mn and 0.05 to 0.80% Cu and furthermore contg. one or more kinds among <=0.7% Fe, <=0.4% Si, <=0.5% Zn, <=0.05% Cr and 0.05% Ti is treated as follows. Namely, the Al alloy ingot is subjected to homogenizing heat treatment at 500 to 600 deg.C for the homogenization of micro segregation and the formation of desired intermetallic compounds. Next, the Al alloy ingot after subjected to homogenizing heat treatment is subjected to hot rolling at 270 to 600 deg.C, thereafter to intermediate rolling (cold rolling) and furthermore to process annealing at 350 to 550 deg.C. In this way, after the structure contg. 0.5 to 3% volume fractional rate of intermetallic compounds having 5X10<2> to 1X10<3>Angstrom diameter is formed, the Al alloy ingot is subjected to finish cold rolling at 40 to 70% cold rolling reduction, by which the objective Al alloy for drawing can be obtd.

Description

[Detailed description of the invention]

(Industrial Application Field) The present invention mainly relates to a method for manufacturing an aluminum alloy for drawing, which is suitable for DRD cans. (Prior art and problems to be solved) Aluminum cans used for beverage cans such as beer and carbonated drinks, food cans, etc.
n: Drawing/re-drawing) processing or [) I (Draw
Cans obtained by the former method are called DRD cans, and those obtained by the latter method are called DI cans. DRD cans are usually cans with a plate thickness of 0.20" and 0.25 mm, and the typical process for manufacturing them is: Coating coil - draw press (drawing process) -> redraw press - beading press (as necessary) This is a process consisting of side bead and neck bead processing depending on the process. At this time, it is particularly important that the aluminum alloy used as the material has the following characteristics (1) to (4). (1) Material strength to obtain the required can bottom strength, (2
) Distortion patterns that impair the surface appearance (see "Basics and Industrial Technology of Aluminum", published by the Light Metals Association (1986), p. 139)
(3) The occurrence of ears after redrawing is small, that is, the directionality is small. (4) The flange workability of the tightening part with the end is excellent. However, in the past, aluminum alloys to which a large amount of Mg was added due to requirement (1) had the drawback of (2),
If the cold rolling rate is increased, the material will have a high selvage and meet the requirements (3).
) had the disadvantage of not satisfying the following. Therefore, there has been a strong demand for a material that simultaneously satisfies requirements (1) to (4) necessary for a DRD can. On the other hand, the inventors of the present invention previously applied for patent application No. 63-0223.
In No. 11, we proposed a method that can simultaneously satisfy these requirements. In this method, the chemical composition is adjusted and the conditions of homogenization heat treatment, hot rolling, and intermediate annealing are regulated to create a structure with a specific size and amount of intermetallic compounds. %). However, for DRD can stock with a higher degree of drawing, there is a demand for material with a lower selvage ratio, and from the perspective of material manufacturing, even if the finishing cold rolling ratio is increased, it is not possible to use a material with a lower selvage ratio. It is desirable that this material be developed, and further development of the material has been desired. The present invention was made to meet the above requirements, mainly for the DRD can. In particular, it is an object of the present invention to provide a method for producing an aluminum alloy for drawing that has high strength and low directionality. (Means for Solving the Problems) In order to achieve the above object, the inventor of the present invention, based on the previous proposal, further conducted intensive research on the manufacturing conditions of aluminum materials, and as a result, the present inventors have determined that by reducing the Mn content, etc. If the composition is adjusted and the conditions of homogenization heat treatment, hot rolling, and intermediate annealing are regulated to obtain a structure with a specific size and amount of intermetallic compounds, it is necessary to perform finish cold rolling at a large cold rolling rate. It has been found that a material with a low selvage ratio can be obtained even if That is, in the present invention, Mg: 0.8 to 1.5%, Mn:
0.30-0.50% and Cu: 0.05-0.80%
Contains as an essential component, Fe: 0.7% or less, S
i: 0.4% or less, Zn: 0.5% or less, Cr: 0.0
One or two of 5% or less and Ti: 0.05% or less
An aluminum alloy ingot containing at least 100% of aluminum with the remainder consisting of Al and impurities is subjected to homogenization heat treatment at 500 to 600°C, hot rolled at 270 to 600°C, and then subjected to intermediate rolling and 350 to 550°C. After intermediate annealing, the diameter is 5
10''~I
The gist of the present invention is a method for producing an aluminum alloy for drawing, which has high strength and low directionality, and is characterized by performing finish cold rolling of 0 to 70%. 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. Mg: Mg is an element that imparts strength, but if it is less than 0.8%, sufficient strength cannot be obtained, and if it exceeds 1.5%, distortion patterns are likely to occur on the can surface during molding. Moreover, work hardening increases when the amount of finish cold rolling is increased, impairing the formability of the material. Therefore, Mgff1 is 0.8-1.5
% range. Mn: Mn provides strength and is an intermetallic compound with Al (Mn, Fe
)Al is an element necessary for the formation of Al, but if it is less than 0.30%, sufficient strength cannot be imparted, and an intermetallic compound with a volume fraction of 0.5% or more cannot be formed. Also, Mn is 0.50
%, texture due to cold working tends to develop and the selvage rate increases. Also, the desired size (5x i
The ratio of intermetallic compounds (o2 to I x 10') increases, and flange workability decreases. Therefore, the amount of Mn is set in the range of 0.30 to 0.50%. Cu: Cu is an element necessary to impart strength, but 0.
If it is less than 0.05%, sufficient effect cannot be obtained, and if it is less than 0.80%,
Exceeding this is not preferable because the strength increases, making it difficult to adjust the strength and deteriorating the corrosion resistance. Therefore, the amount of Cu is in the range of 0.05 to 0.80%. Each of the above elements is contained as an essential component, but in the present invention, one of the following elements Fe, Si, Zn, Cr and Ti is contained.
Contain an appropriate amount of one or more seeds. The amount of Fe (Fa) is effective in imparting strength and also + (Fe, Mn
)Si, Al12 as crystallized products, it has the effect of preventing seizure during molding, and at the same time, the above-mentioned Mn and (Mn, Fe
) Al is an element that forms an intermetallic compound. However, if it exceeds 0.7%, coarse intermetallic compounds (Mn, F
e) A Q, formed and of desired size (5X10
”~I
3%) cannot be obtained. Therefore, the amount of Fe is 0.
7% or less. Si: Sj is an element that provides an anti-seizure effect during molding as a crystallized product of the above-mentioned (Fe, Mn) SLAQiz, but if it exceeds 0.4%, coarse crystallized products are generated. This will impair moldability. Therefore, the amount of Si is 0.4%
The following shall apply. Zn: Zn is an element that provides strength, but if it exceeds 0.5%, corrosion resistance deteriorates, so the amount of Zn is set to 0.5% or less. Cr, 'ri: Both Cr and Ti are elements added to finely control the structure, but if each exceeds 0.05%, coarse intermetallic compounds are generated and formability is impaired, so Cr The amount of Ti and the amount of Ti are each 0.05% 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, below 500°C, sufficient homogenization heat treatment (homogenization of microsegregation) and desired intermetallic compounds (Mn,
Fe) A I2. (Diameter 5 x 102 ~ I x 1
If the temperature exceeds 600°C, there is a risk of eutectic melting, etc., which is not preferable. Note that the heating time is not particularly limited, but a range of 3 to 24 hours at the above temperature 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 mm. At this time, if rolling is performed 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 upper limit temperature of 600°C is a value defined by the upper limit of the homogenization heat treatment temperature of 600°C. After that, intermediate rolling (cold rolling) is performed, and the
Intermediate annealing is performed at a temperature of ℃ to make a soft material. If the intermediate annealing temperature is lower than 350°C, a sufficiently soft material cannot be obtained;
If the temperature exceeds 50℃, abnormally coarse particles will occur, so
The temperature should be in the range of ~550°C. Note that the heating time for intermediate annealing is 2 to 4 hours in the temperature range of 350 to 400°C, but in the case of high-temperature treatment using a continuous annealing furnace, for example,
It is best to aim for a heating time of 0.5 to 10 seconds at 0°C. Through the above manufacturing process, a structure having a desired intermetallic compound, which is a feature of the present invention, can be obtained. The main intermetallic compounds are (Mn, Fe)Al, and metallurgically speaking, they mainly belong to precipitates (D 1spersoids), and as mentioned above, chemical composition (
In particular, by optimal combinations of Mn, Fe content), homogenization heat treatment, and hot rolling temperature, the average diameter of
X 10'8 and a volume fraction of 0.5 to 3% can be obtained. If the size is less than 5 x 102, the strength of the material will be too high, reducing moldability, and I
If there are many pieces larger than X10', cracks may occur during the molding process, which is not preferable. Further, if the 5 volume fraction is less than 5%, the structure cannot be made sufficiently fine. If it exceeds 3%, it is not preferable because it reduces moldability. Further, according to the present invention, the amount of Mn is reduced to 0.30-0°50%.
Therefore, (M n , Fe) A Q s
The amount of carbon produced is smaller than before, and the development of texture during cold working is smaller, making it possible to obtain a material with relatively low selvage even if 40 to 70% of the cold working is performed in the primary process. effect at the same time. Finally, the soft material containing the desired intermetallic compound is subjected to cold working to form a hard material, but sufficient strength cannot be obtained at a cold rolling rate of less than 40%. On the other hand, 70
When the cold rolling rate exceeds 3%, the cold rolling develops a texture in which crystal grains are oriented in the preferential direction, resulting in directional properties of the material, resulting in an edge height of approximately 3% or more when forming into cans. Increased trimming after molding is required, significantly reducing product value. Therefore, the cold rolling rate in finish rolling is in the range of 40 to 70%. Through the above steps, a plate material having a thickness of approximately 0.20 to 0.25 m+s is obtained. After painting, this plate material is formed into a desired can by a DRD process in which drawing is performed two to three times using a conventional method. (Example) Next, an example of the present invention will be shown. Prong A ± An aluminum alloy ingot with a thickness of 600n+m having the chemical composition shown in Table 1 was melted using the DC casting method, and after surface cutting,
Homogenized heat treatment at 75℃ x 6hrs, 550~300℃
Hot rolling was performed at a temperature of 0.degree. C. to obtain a hot coil with a thickness of 3.5 mm. Next, it was intermediate rolled to form a 0.50 mmt coil, subjected to intermediate annealing at 500°C for 3 seconds in a continuous annealing furnace, and finished cold rolled (cold rolling ratio 45%) to form a 0.22a+mt hard plate. The obtained material was examined for the size and amount of intermetallic compounds, and also subjected to as-manufactured and painted heat treatment (200'CX20
In addition to examining the mechanical properties after m1n), the selvedge ratio, surface distortion pattern, and flange workability were also evaluated. The results are also listed in Table 1. Note that the selvage ratio was determined using a punch diameter of 40 ml φ and a drawing ratio of 40%. In addition, the surface distortion pattern and flange workability are O (good).
It was evaluated by marking it as 0 or . (defective). From Table 1, it can be seen that the aluminum alloy plates of Invention Examples Ncl to Ha 5 all have intermetallic compounds in the size and amount within the range of the invention, have high strength, have no surface distortion pattern, and have a high selvedge ratio and flange processing. It can be seen that it has excellent properties. On the other hand, although the comparative examples exhibit high strength, surface distortion patterns occur and most of them have poor selvage ratio and flange workability.

[Left below]

Regarding the aluminum alloy with Na 1 in Table 1, the second
Aluminum alloy hard plates having a final plate thickness of 0.22 mm were manufactured using various manufacturing processes under the conditions shown in the table. The material properties of the obtained material were evaluated in the same manner as in Example (2). The results are also listed in Table 2. From the same table, it can be seen that the aluminum alloy plates of Invention Examples No. 11 to No. 17 all have high strength, no surface distortion pattern, and have excellent characteristics with a low selvage rate. On the other hand, the comparative example is
Although it has chemical components within the scope of the present invention and has high strength, it is poor in any of the selvedge ratio, surface distortion pattern, rough surface, and flangeability.

[Left below]

(Effects of the Invention) As detailed above, according to the present invention, homogenization heat treatment and hot rolling conditions are regulated and applied to an aluminum alloy having a specific chemical composition, and metal of a predetermined size and amount is produced. Since a structure having intermediate compounds is obtained, it is possible to produce an excellent aluminum alloy hard plate for drawing that has high strength, has no surface distortion pattern, and has low directionality even at a high finishing cold rolling rate. It is particularly suitable for manufacturing DRD cans.

Claims (1)

[Claims] In weight% (the same applies hereinafter), Mg: 0.8 to 1.5%, M
n: 0.30-0.50% and Cu: 0.05-0.8
Contains 0% as an essential component, and further contains Fe: 0.7% or less, Si: 0.4% or less, Zn: 0.5% or less, Cr: 0
．． An aluminum alloy ingot containing one or more of Ti: 0.05% or less and Ti: 0.05% or less, with the remainder consisting of Al and impurities, is subjected to homogenization heat treatment at 500 to 600 ° C. After hot rolling at ℃, intermediate rolling and intermediate annealing at 350 to 550℃ are performed to reduce the diameter to 5.
× 10^2 to 1 × 10^4 Å intermetallic compound in a volume fraction of 0.5 to 3%, and then a cold rolling rate of 40
A method for producing an aluminum alloy for drawing having high strength and low directionality, the method comprising performing finish cold rolling of ~70%.