JP2001073058A - Aluminum alloy sheet for can end excellent in blowup resistance and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an aluminum alloy sheet having strength close to that of the can end of a 5182 alloy, excellent in blowup resistance, having high strength and moreover excellent in recycling properties. SOLUTION: As to an aluminum alloy sheet having a compsn. contg. 0.6 to 1.5% Mn, 1.2 to 3.0% Mg, 0.2 to 0.5% Si, 0.1 to 0.4% Cu, 0.1 to 0.5% Fe and 0.001 to 0.2% Ti, and the balance Al with inevitable impurities, in its metallic structure, the average grain size of intermetallic compds. is <=1 μm As to this producing method, the molten metal 8 of an alloy having the above compsn. is cast into a sheet material of <=10 mm thickness at a solidifying speed of >=100 deg.C/sec by a continuous casting and rolling method, then, the cast sheet 9 is cold-rolled, this sheet material is subjected to solution heat treatment of executing heating to the temp. range of 500 to 590 deg.C at a temp. rising rate of >=10 deg.C/sec, and the metallic structure contg. intermetallic compds. of <=1 μm average crystal grain size is formed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an aluminum alloy sheet for a can end (end) of a beverage can or the like and a method for producing the same, which has various properties such as strength, corrosion resistance, moldability and the like. In particular, even when the end is in an inverted state called buckling due to internal pressure,
The present invention relates to an aluminum alloy plate for a can end of a beverage or the like which does not crack at the end and does not cause the contents to blow out from the end, that is, has excellent blow-up resistance, and an improvement technique of a manufacturing method thereof.

[0002]

2. Description of the Related Art With an increase in demand for canned beverages and the like, recently, so-called DI (Deep drawing & Ironing) cans made of an aluminum-based alloy suitable for the containers have been mass-produced. This DI made of aluminum base alloy
As a general method of manufacturing a can body, an aluminum-based alloy plate is deep-drawn in multiple stages, then ironed to form a can body, and after baking paint, use of a relatively expensive lid member material Perform neck processing to reduce the diameter to reduce the amount. The aluminum-based alloy sheet used here is required to have both sufficient strength after can making and formability to withstand multi-stage deep drawing and ironing.

[0003] An aluminum can for beverages is composed of two pieces, a body (can body) and an end (can lid).
System, for example, American Aluminum Association Standard (AA) 3
004 alloy (Si: 0.3% or less, Fe: 0.7% or less,
Cu: 0.25% or less, Mn: 1.0 to 1.5%, Mg:
0.8-1.3%, Zn: 0.25% or less, balance Al) is widely used. In order to manufacture an aluminum alloy sheet for deep drawing from this alloy, first, an ingot of this alloy is hot-rolled, and then cold-rolled to a sheet having an appropriate thickness. Intermediate annealing is performed, and a hardening process by cold rolling is performed according to the required strength.

On the other hand, as a material for a can end, a high strength Al-Mg based 5182 alloy (Si:
0.2% or less, Fe: 0.35% or less, Cu: 0.15%
Hereinafter, Mn: 0.2 to 0.5%, Mg: 4.0 to 5.0%,
Zn: 0.25% or less, Ti: 0.1% or less, balance Al)
Are mainly used.

[0005] In recent years, social demands for recycling of food containers and the like have been increasing more and more, and the rate of collecting and reusing used beverage cans, that is, the recycling rate has been increasing year by year. However, in general, the body material and the end material are made of different component aluminum alloys as described above. Adjustments have to be made, which has led to an increase in recycling costs. For this reason, an attempt has been made to make a so-called unialloy in which the body material and the end material are made of the same component alloy.

However, the strength of the 3004 alloy for the can body is lower than that of the 5182 alloy for the can end. In view of the need to increase the thickness, and considering the excellent rollability of the 3004 alloy, there is a problem that the manufacturing cost at the time of recycling the end of the can is not necessarily reduced because the amount of the alloy used is increased. Further, in the case of the end material of the 5182 alloy, with the passage of time after molding, the pressure resistance decreases due to aging softening, and may be lower than a required value. That is, although the 5182 alloy is a composition system to which 4-5% of Mg is added in order to improve the strength, it is required that it is not preferable to have one defect per 100,000 in an aluminum can. Therefore, it is considered that such a hard aluminum alloy containing 4 to 5% Mg is difficult to reuse.

Therefore, the present inventors have found that the recyclability is excellent, and the strength of the alloy does not change with time as compared with the 5182 alloy.
For the purpose of using an Al-Mn alloy as an end material, various studies were made on a method for improving strength.

First, as a method of increasing the strength of an Al—Mn alloy, a method of increasing the amount of additional elements such as Mg, Mn, Si, and Cu, and a method of increasing the final cold rolling reduction are known methods. In addition, intermediate annealing is performed at a high temperature, and Mg, Si,
A method for forming a solution of Cu in an Al base is also widely used. According to this method, not only the work hardenability at the time of cold rolling is increased, but also the age hardenability is imparted, and when baking is applied to a rolled plate or a molded product thereof, it suppresses annealing softening or precipitation hardening. Can be caused. Furthermore, a method of cold-rolling a rolled sheet that has been subjected to a solution treatment, performing aging treatment on the way, and remarkably increasing the work hardenability during subsequent cold rolling has been studied.

[0009]

However, according to the study of the present inventors, when a can end is manufactured using an Al-Mn-based alloy reinforced by these methods, blow-up can be performed in comparison with an Al-Mg-based alloy. The problem of easy occurrence became clear. That is, at present, an easy open end type in which a tab for cutting and raising is provided at the center of the end of the beverage can is widely used. The easy open end type has an end along a cut-and-raised portion of the end (a portion corresponding to the opening constituting the spout) in order to facilitate the cut-and-raise operation of the spout-forming tab. A process called a score process in which a notch having a depth of about 2/3 of the thickness of the material is formed by a press process is performed. As described above, the can end is required to have an excellent opening property when the opening is opened by the tab, but is also required to have a high pressure resistance of the opening so that the opening is not easily opened by the internal pressure of the can. .

In the manufacture of aluminum cans 3004
After a beverage is filled in a cup-shaped body made of an aluminum alloy plate made of an alloy, an end made of a 5182 alloy is placed over an opening of the body, and the end periphery is fixedly wound around the body. FIG. 3 shows this state. The end 2 is attached to the opening of the body 1, and the peripheral edge of the end 2 is wound and joined to the opening of the body 1. Also,
A peripheral groove 2b for forming a concave portion 2a called a countersink inside the aluminum can is formed in a peripheral portion of the end 2 of the aluminum can.

When an internal pressure is applied to the aluminum can of this configuration to increase the internal pressure, a portion 2d of the end 2 inside the countersink portion is usually referred to as a buckling which protrudes outside the aluminum can as shown in FIG. This buckling pressure is used as the pressure resistance strength. However, Al-Mn reinforced by the method described above
In the case of the end 2 using a base alloy, if there is a defect in the shape of the end 2 or the like, the portion that is scored and cut to form an opening causes the buckling of the end 2 as described above. There is a possibility that the opening may be broken before the end is formed, or a crack may be generated in the opening due to the deformation of the end 2 at the time of buckling. If the opening seems to crack or break, in the case of a beverage can, the beverage may squirt and scatter around, causing secondary damage. For example, when an aluminum can is left in a car that has become hot due to direct sunlight in summer, the internal pressure of the can increases due to thermal expansion, and if the opening at the end of the can is damaged or cracked, the beverage may be blown out. .

[0012] From such a background, in the aluminum can, the relation of (breaking pressure)> (buckling pressure), that is, buckling occurs first with an increase in pressure, and breakage occurs with further increase in pressure. Al-M reinforced by the method described above
In the case of a can end using an n-based alloy, if there is a defect in the shape of the end as described above, a relationship of (breaking pressure) ≦ (buckling pressure) may be obtained, and the breakage may occur before buckling. In some cases. That is, before reaching the buckling shown in FIG. 4, the end 2 swells to the outside as shown in FIG. 5 due to the internal pressure. At this time, the opening of the can end 2 may be damaged or cracked. there were.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and has an object to have strength close to that of a conventional 5182 alloy can end, excellent blow-up resistance, and high strength. A with excellent recyclability
An object of the present invention is to provide an aluminum alloy plate for a can end which is excellent in l-Mn-based blow-up resistance.

[0014]

SUMMARY OF THE INVENTION The present inventors have conducted research from the above viewpoints to develop Al-Mn alloys for beverage can ends having excellent blow-up resistance. Coarse intermetallic compounds such as Al-Fe-Mn are present in the Al-Mn alloy end material, and fine cracks are likely to occur at the time of scoring starting from the coarse intermetallic compounds. In this case, when a high internal pressure acts, blow-up occurs. Was found to occur easily. Further, as a result of further research, it was found that the amount of Fe in the aluminum alloy of this system was reduced as much as
It has been found that blow-up can be suppressed by using an intermetallic compound such as an Al-Fe-Mn system having a particle size of not more than μm. Further, the amounts of Mn and Cu are controlled in appropriate ranges, and the yield strength in the state of coating or laminating a resin film is 300 MPa.
With the above, a research result that a sufficient pressure resistance can be obtained was obtained.

Therefore, in order to solve the above-mentioned problems, the present invention provides a method for producing Mn: 0.6 to 1.5% (% by weight, hereinafter the same), Mn:
g: 1.2-3.0%, Si: 0.2-0.5%, Cu:
0.1 to 0.4%, Fe: 0.1 to 0.5%, Ti: 0.0
An aluminum alloy sheet containing 0.01 to 0.2% and having a balance of Al and inevitable impurities, wherein the average grain size of the intermetallic compound in the metal structure is 1 μm or less.

Further, the present invention relates to an aluminum alloy plate obtained by subjecting the above-mentioned aluminum alloy plate to baking coating or laminating a thermoplastic resin film, which has a proof stress of 3.
It is characterized by being at least 00 MPa.

Next, the production method of the present invention employs the following method: Mn: 0.6
1.5%, Mg: 1.2-3.0%, Si: 0.2-0.2%.
5%, Cu: 0.1 to 0.4%, Fe: 0.1 to 0.5%,
An aluminum alloy melt containing 0.001 to 0.2% Ti and having a balance of Al and unavoidable impurities is formed by continuous casting and rolling at a solidification rate of 100 ° C./sec or more to a thickness of 10 m.
m, and then cold-rolled the cast sheet.
A solution treatment was performed in which the material was heated to a temperature range of 590 ° C. and held for 30 seconds or less.
An object of the present invention is to provide a method for producing an aluminum alloy plate for a can end having excellent blow-up resistance, characterized by having a metal structure having an intermetallic compound of not more than μm. Further, the present invention is characterized in that the aluminum alloy plate described above is baked or coated, or by lamination with a thermoplastic resin, the plate material is heated to 200 to 300 ° C., and score processing is performed using the plate material. I do.

The reason for limiting the alloy composition and structure in the present invention as described above will be described below. "Mn": Mn has an effect of increasing strength, but when its content exceeds 1.5% (% by weight, the same applies hereinafter), A
1, forming a coarse intermetallic compound with Fe, Si, etc., lowering the cold rolling property and the end workability, facilitating the occurrence of fine cracks starting from the intermetallic compound at the time of score processing, and causing blow-up. Make it easier. On the other hand, Mn
If the content is less than 0.6%, the desired strength-improving effect as an end material cannot be obtained, and the recyclability decreases.

"Mg": Mg has the effect of increasing the strength by forming a solid solution in the matrix, but if its content exceeds 3.0%, the castability and the rollability are significantly reduced, and the melting point of the alloy is lowered. Therefore, the homogenizing temperature and the intermediate annealing temperature for performing the solution treatment cannot be increased. For this reason, it is difficult to form a solution of Mn, Mg, Si, and the like, and the amount of coarse intermetallic compounds of these elements increases, so that the blow-up resistance decreases. On the other hand, if the Mg content is less than 1.2%, the desired strength improving effect cannot be obtained.

"Si": Si has a function of improving the strength by precipitating as a fine Mg ₂ Si compound. However, if the content exceeds 0.5%, the solution cannot be completely dissolved, and a coarse intermetallic compound such as an Al—Fe—Mn—Si system or Mg ₂ Si is formed. The upper limit is set to 0.5%. On the other hand, if it is less than 0.2%, a desired strength improving effect cannot be obtained. “Cu”: Cu dissolves in the base material and
It acts as a u-Mg-based compound to improve the strength, but if the content is less than 0.1%, a sufficient effect cannot be obtained. On the other hand, if the content exceeds 0.4%, castability and Corrosion resistance may be significantly reduced.

"Fe": Fe easily forms a coarse intermetallic compound with Al, Mn, Si and the like, lowers toughness, easily causes fine cracks during score processing, and easily causes blow-up. Therefore, it is preferable that the content is small, but if it is less than 0.1%, the purity of the metal becomes high, which leads to an increase in manufacturing cost. That is, since a small amount of Fe is contained as an impurity in a normal aluminum ingot, an aluminum ingot having an Fe content of less than 0.1% becomes expensive, and this expensive ingot is used. This leads to increased manufacturing costs. Further, by reducing the Fe content to 0.5% or less, the average particle size of the Al-Fe-Mn intermetallic compound can be reduced to 1 µm or less. In addition,
When about 0.4 to 0.5% of Fe is contained, Al-Fe-M
Although the average particle size of the n-type intermetallic compound tends to increase,
By manufacturing a sheet material from a molten metal by a continuous casting and rolling method as described in a manufacturing method to be described later, the cooling rate can be made faster than that of a DC casting method or the like, whereby the average grain size of the Al-Fe-Mn intermetallic compound can be increased. The diameter can be reduced.

"Ti": Ti is added for refining the cast structure. However, if it is less than 0.001%, the effect is not obtained, and if it exceeds 0.2%, coarse crystals increase.
Moldability and blow-up resistance are reduced.

Next, the reason why the average particle size of the intermetallic compound is set to 1 μm or less in the finally obtained plate material is that when the average particle size of the intermetallic compound exceeds 1 μm, the intermetallic compound starts from the intermetallic compound. This is because fine cracks are likely to occur at the time of score processing, and blow-up may occur when a high internal pressure is applied. Here, as the intermetallic compound, an Al—Fe—Mn based intermetallic compound, a Mg ₂ Si based intermetallic compound, and the like can be exemplified.

[0024]

Embodiments of the present invention will be described below in detail. The aluminum alloy sheet for a can end according to the present invention has Mn: 0.6 to 1.5%, Mg: 1.2 to 3.0%,
Si: 0.2 to 0.5%, Cu: 0.1 to 0.4%, Fe:
0.1 to 0.5%, Ti: 0.001 to 0.2%,
An aluminum alloy plate having a composition of the balance of Al and inevitable impurities, wherein the average grain size of the intermetallic compound in the metal structure is 1 μm or less. The thickness of the aluminum alloy plate for the can end used here may be 0.31 mm or 0.28 mm thick. It is preferable that the aluminum alloy plate having the above composition is subjected to baking coating or an aluminum alloy plate in which a thermoplastic resin film such as PET (polyethylene terephthalate) is laminated, and the proof stress is set to 300 MPa or more.

In order to manufacture an aluminum alloy plate having the above composition, for example, a molten alloy having the above composition is prepared by using FIG.
First, a primary sheet material is manufactured by a continuous casting and rolling method using a continuous casting and rolling machine as shown as an example. The continuous casting and rolling mill shown as an example in FIG. 1 has rolls 5 and 6 arranged vertically.
A feeder chip 7 for supplying molten metal is provided at the inlet of the roll gap, and the molten alloy 8 having the above composition is fed from the feeder chip 7 into the roll gap between the rotating rolls 5 and 6, and at the same time, the molten alloy is cooled and solidified. This is a twin-roll type in which a cast plate 9 having a desired thickness is obtained and rolled around a take-up roll 10. In FIG. 1, reference numeral 8 'indicates a solid-liquid coexistence region in which the molten metal 8 starts to solidify and becomes solid. According to the continuous casting and rolling apparatus shown in FIG. 1, the thickness of the cast plate 9 is 10 mm or less, preferably,
Those having a thickness of about 3 to 6 mm can be manufactured directly from the molten metal.

The cooling rate in the continuous casting and rolling method is as follows:
It can be much faster than the general casting method of casting a mold to produce a normal ingot (0.5 to 40 ° C./sec in cooling rate), and a cooling rate of 100 to 300 ° C./sec. can do. If the cast plate 9 is manufactured in such a cooling rate range, the particle size of the Al—Fe—Mn intermetallic compound and the Mg ₂ Si intermetallic compound generated in the metal structure in the Al alloy having the above-described composition is determined. It can be made finer than in a general casting method. Starting from such a cast plate 9, if an aluminum alloy plate for end is formed by the following manufacturing process, the average particle size of the intermetallic compound present in the structure can be reliably reduced to 1 μm or less. . Further, in such a cooling rate range, specifically, a cooling rate in a range of 150 to 300 ° C./sec can be preferably employed. The cast plate 9
In the cooling rate of 0.5 to 40 ° C /
According to a normal casting method in the range of seconds, it is difficult to reduce the particle size of the intermetallic compound to 1 μm or less even if the following steps are performed.

As for the method of continuous casting and rolling of the molten alloy, any of a twin-roll type continuous casting apparatus shown in FIG. 1 and a continuous casting apparatus using a combination of a grooved casting wheel and a belt may be used. Of course.

The cast plate 9 manufactured as described above is subjected to cold rolling, followed by solution treatment. This solution treatment is performed by heating the cast plate 9 at a heating rate of 10 to 200 ° C./S for 48 hours.
Heat to a temperature of 0 ° C. or higher and lower by about 5 ° C. from the melting point, and keep in this temperature range for 0 to 30 seconds (0 seconds hold means that cooling starts immediately when the target temperature is reached). Thereafter, a cooling process is performed. In this step, the cold-rolled aluminum alloy plate is heated to 10 to 200 ° C.
By rapidly heating and recrystallizing at a heating rate of / S, a fine and isotropic recrystallization texture can be obtained. Further, in the above step, heating is performed to a temperature of 480 ° C. or higher and about 5 ° C. lower than the melting point.
After holding for 0 seconds, 10-200 ° C /
By cooling at a cooling rate of S, Mg, Cu, and Si can be sufficiently dissolved. In this case, if the solution is insufficient, sufficient strength cannot be obtained in the end aluminum alloy plate finally obtained.

After the solution treatment, the sheet material is subjected to final cold rolling,
Thickness necessary for end use, for example, the target thickness is 0.3
In the case of 1 mm, final cold rolling is performed to a thickness of 0.31 mm to obtain an aluminum alloy plate for an end. If the final cold rolling reduction is low, sufficient strength cannot be obtained in the end aluminum alloy sheet. In the final cold rolling, the working is preferably performed at a rolling rate of 40 to 75% to obtain a final thickness. The final cold rolling reduction here is 4
If it is less than 0%, an aluminum alloy sheet having sufficient strength cannot be obtained, and if the cold rolling reduction exceeds 75%, the difference between the tensile strength and the proof stress decreases, and blow-up becomes easy. The range of the processing rate is more preferably in the range of 45 to 60%.

The final rolled sheet obtained in the above steps is subjected to a surface treatment such as chromate treatment, followed by baking coating or lamination with a thermoplastic resin, according to a conventional method. In the baking step, heating is performed at 220 to 300 ° C. for about 2 minutes or less, and in the thermoplastic resin laminating step, the heating is performed at 200 to 280 ° C.
For 3 to 60 seconds.

The finally obtained aluminum alloy plate for end is subjected to scoring to make a cut having a depth of about 2/3 of the thickness of the aluminum alloy plate, and is provided for canned beverages.

The aluminum alloy plate obtained by the above manufacturing method is an aluminum alloy plate having proper contents of Mn, Mg, Si, Cu, Fe, and Ti;
In addition, since the average particle size of the intermetallic compound is 1 μm or less manufactured under the above-described appropriate manufacturing conditions, it is possible to prevent blow-up due to an increase in internal pressure, which is a problem particularly when used for beverage cans. it can. That is, among the above-mentioned additional elements, Fe and Mn are Al and Al-Fe-Mn-based alloys together with Al.
Since it is easy to generate a coarse intermetallic compound of μm or more, if the average particle size of this coarse intermetallic compound is set to a value exceeding 1 μm, when it is used for a can end, in order to constitute a drinking can of a beverage can When a cut is made by scoring, fine cracks may be generated starting from the intermetallic compound. However, by manufacturing under appropriate conditions as the composition range, a coarse intermetallic compound having an average particle size exceeding 1 μm may be obtained. The number of compounds can be reduced, and the generation of fine cracks during score processing can be suppressed. Therefore, when the end of the beverage can is configured using the aluminum alloy plate according to the present invention, the internal pressure of the beverage can is increased for some reason, such as when the beverage can is left in a high-temperature automobile in summer to increase the internal pressure. Even if the pressure rises abnormally, there is no possibility that blow-up will occur from the fine cracks and the contents will be blown out.

If the aluminum alloy sheet has the composition according to the present invention, it has the same strength as the 5182 alloy which has been used as a conventional end material, and has excellent blow-up resistance as described above. Furthermore, compared to the 5182 alloy containing about 4 to 5% of Mg, the amount of Mg is reduced and the Mn content is increased, and the Al-Mn-based composition is maintained while the Al-Mn-based recyclability is excellent. There is a feature having.

[0034]

EXAMPLES Aluminum alloys having the respective compositions shown in Nos. 1 to 11 in Table 1 below were cast into a cast plate having a thickness of 5 mm by a continuous casting and rolling method at a solidification rate of 150 ° C./sec. In Table 1, N
Sample No. o.12 was hot-rolled by a DC casting method (solidification speed: 10 ° C./sec) to obtain a plate having a thickness of 7 mm. Next, these sheets were cold-rolled to a thickness of 0.62 mm, subjected to an intermediate annealing treatment in which the sheets were rapidly cooled to 520 ° C. at a rate of 15 ° C./sec, and immediately cooled, and finally 0.31 mm thick by cold-rolling. An aluminum alloy plate for an end was obtained. Next, the thickness of 12 μm
Was laminated and subjected to a heat treatment at 260 ° C. for 20 seconds to strengthen the adhesion of the resin film. Finally, a notch having a depth of 2/3 of the aluminum alloy plate is formed by a press device by scoring to form a drinking spout, and a cut-and-raised tab can be attached to serve as a can end.

"Table 1" Sample No. Si Fe Cu Mn Mg Zn Ti 1 0.28 0.18 0.40 1.02 2.54 0.10 0.03 2 0.28 0.17 0.30 0.70 1.80 0.09 0.02 3 0.27 0.17 0.30 1.01 2.20 0.09 0.02 4 0.29 0.28 0.20 0.99 2.20 0.09 0.025 0.28 0.50 0.20 1.03 2.86 0.10 0.02 6 0.27 0.60 * 0.42 0.69 2.76 0.09 0.02 7 0.28 0.32 0.43 * 0.69 2.86 0.10 0.02 8 0.28 0.28 0.30 0.50 * 2.00 0.10 0.02 9 0.27 0.28 0.30 1.60 * 2.79 0.09 0.02 10 0.29 0.28 0.20 0.99 2.20 0.09 0.02 11 0.29 0.28 0.20 0.99 2.20 0.09 0.02 12 0.29 0.43 0.40 0.99 2.00 0.08 0.02

[Table 2] Sample No. Intermediate annealing Final pressure Tensile strength Yield Elongation Average grain A B Plate thickness (mm) Elongation (%) (MPa) (MPa) (%) Diameter (μm) (%) ( (%) 1 0.78 60 381 329 8.7 0.7 100 0 2 0.78 60 350 301 6.0 0.7 100 0 3 0.56 45 361 302 8.7 0.7 100 0 4 0.78 60 368 316 6.5 0.8 100 0 5 0.62 50 375 315 9.1 0.9 100 0 6 0.78 60 385 332 8.8 1.4 0 100 7 0.78 60 386 335 8.9 0.8 0 100 8 0.78 60 350 296 6.1 0.8 100 0 9 0.78 60 389 340 8.5 1.5 60 40 10 1.29 76 * 377 331 6.5 0.8 40 60 11 0.50 38 * 342 290 7.5 0.8 100 0 12 0.78 60 366 316 7.4 3.0 40 60

In Table 2, A% and B% both indicate the ratio of the form during the pressure resistance test, A indicates the ratio of the sample that was buckled without blowing up, and B indicates the ratio of the sample that was blown up. . In this pressure resistance test, an aluminum alloy plate was formed into a can end having a diameter of 60 mm, and a cut end (a plate thickness of 2 mm) was formed at the end of the can by scoring.
切 り), the can end is wound around a can body with a bottom, the bottom of the body is cut off after winding, the can with the bottom is set in a pressure device, and the inside of the body is cut. Then, internal pressure was applied to the can end by using a pressurizing device, and it was confirmed whether the wound can end was buckled or blown up.

As is evident from the results shown in Table 2, the compositions of the present invention, Nos. 1, 2 and
Samples Nos. 3, 4, and 5 exhibited a yield strength in the range of 300 MPa or more (yield strength equivalent to that of the 5182 alloy), and the average particle size of the intermetallic compound was found to be as small as 1 μm or less. Further, samples Nos. 1, 2, 3, 4, and 5 buckled without blow-up due to an increase in internal pressure, whereas other samples partially blow-up before buckling. There was something. In contrast, No. 6
The sample No. was a sample in which the content of Fe was increased to 0.6%, but the average particle size of the intermetallic compound was large, and the sample was blown up by 100%. The sample of No. 7 was a sample in which Cu was increased to 0.43%, and this sample was also blown up. N
Sample No. o.8 was a sample in which Mn was reduced. However, although no blow-up was performed, tensile strength and proof stress were reduced. N
The sample of No. 9 was a sample in which Mn was increased, but 40% of the samples blown up. The sample of No. 10 had a final rolling reduction of 76%, but the sample of 60% blow-up. The sample of No. 11 had a final rolling reduction of 38%, but did not blow up, but lacked tensile strength and proof stress. Next, No. manufactured by the DC casting method.
Although the sample No. 12 was in a preferable range in terms of alloy composition, the average particle size of the intermetallic compound was remarkably large,
0% of the sample blown up.

[0039]

As described above, the aluminum alloy plate of the present invention is an aluminum alloy plate having an appropriate content of Mn, Mg, Si, Cu, Fe, and Ti. Since the Fe content and the Mn content that form the -Mn-based coarse intermetallic compound are set to appropriate contents, the average particle size of the coarse intermetallic compound can be 1 µm or less. When the average particle size of such an intermetallic compound is set to a value exceeding 1 μm, when the end material is used as a can end material, when the cut is made by scoring to constitute a drinking can of a beverage can, the intermetallic compound is removed. Although there is a possibility that a fine crack may be generated as a starting point, the average particle size of the intermetallic compound can be reduced to 1 μm or less by setting the addition amount of the element in an appropriate range. Can be suppressed. Therefore, when the end of the beverage can is constituted by using the aluminum alloy plate according to the present invention, when the internal pressure is abnormally increased by leaving the beverage can in a high-temperature automobile in summer, for example, the beverage can is caused by any cause. Even if the internal pressure rises abnormally, there is no possibility that blow-up will occur from the fine cracks and the contents will be blown out.

The aluminum alloy plate having the composition according to the present invention has the same strength as the 5182 alloy used as a conventional end material, and has excellent blow-up resistance as described above. Furthermore, the aluminum alloy plate of the present invention is a composition system similar to an Al-Mn system in which the amount of Mg is smaller and the Mn content is larger than that of the 5182 alloy, as compared with the 5182 alloy containing about 4 to 5% of Mg. As a result, there is an effect of having excellent characteristics in recyclability.

Next, using an aluminum alloy having the above composition, a continuous cast rolling method is used to form a cast plate having a thickness of 10 mm or less at a solidification rate of 100 ° C./sec or more, and then cold rolling, solution treatment, and final cold rolling. By performing the above, an aluminum alloy sheet for a can end in which the average particle size of the intermetallic compound is reliably suppressed to 1 μm or less can be obtained. In the case of an aluminum alloy plate in which the average particle diameter of the intermetallic compound is suppressed to 1 μm or less as described above, an aluminum alloy plate for a can end that does not generate blow-up even when a process such as cutting is performed by scoring is performed. Can be provided.

[Brief description of the drawings]

FIG. 1 is a diagram showing a cross-sectional structure of a main part of an example of a continuous casting and rolling device used in carrying out an example of the method of the present invention.

FIG. 2 is a view showing a state in which a plate material rolled by the apparatus is wound up.

FIG. 3 is a cross-sectional view showing an example of a joint portion between a body and an end of a general aluminum can.

FIG. 4 is a cross-sectional view showing a state in which buckling is caused by deformation of an end material in a general aluminum can.

FIG. 5 is a cross-sectional view showing a state in which an end material swells in a general aluminum can.

[Explanation of symbols]

1 ... (can) body, 2 ... (can) end, 2a ... counter sink, 2b ... circumferential groove, 2d ... part, 5, 6, ...
-Roll, 7: Feeder chip, 8: Molten metal, 9: Cast plate.

────────────────────────────────────────────────── ───Continuation of the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C22F 1/00 630 C22F 1/00 630A 673 673 681 681 682 682 685 685 691 691A 691B 691C (72) Inventor Hiroshi Saito 85 Hiramatsu, Susono City, Shizuoka Prefecture F-term in the Technology Development Center of Mitsubishi Aluminum Corporation (reference) 4E004 DB03 NA03 NB07 NC08 SE03 TA07 TB02

Claims (4)

[Claims] 1. Mn: 0.6 to 1.5% (% by weight, hereinafter the same), Mg: 1.2 to 3.0%, Si: 0.2 to 0.5%,
Cu: 0.1 to 0.4%, Fe: 0.1 to 0.5%, Ti:
An aluminum alloy sheet containing 0.001 to 0.2% and having a balance of Al and inevitable impurities, wherein the average grain size of the intermetallic compound in the metal structure is 1 μm.
An aluminum alloy plate for a can end excellent in blow-up resistance, characterized in that: 2. An aluminum alloy plate obtained by subjecting the aluminum alloy plate according to claim 1 to baking coating or laminating a thermoplastic resin film, the proof stress of which is 300M.
An aluminum alloy plate for a can end excellent in blow-up resistance, characterized by having a pressure of Pa or more. 3. Mn: 0.6 to 1.5% (% by weight, hereinafter the same), Mg: 1.2 to 3.0%, Si: 0.2 to 0.5%,
Cu: 0.1 to 0.4%, Fe: 0.1 to 0.5%, Ti:
An aluminum alloy melt containing 0.001 to 0.2% and having a balance of Al and unavoidable impurities is cast by continuous casting and rolling at a solidification rate of 100 ° C./sec or more into a sheet having a thickness of 10 mm or less. After cold-rolling the cast sheet, the sheet material is cooled to 500 to 590 ° C. at a rate of 10 ° C./sec or more.
Blow-up resistance characterized by applying a solution treatment in which the alloy is heated to the temperature range described above and maintained for 30 seconds or less, and further subjected to final cold rolling to obtain a metal structure having an intermetallic compound having an average particle size of 1 μm or less. Method for manufacturing aluminum alloy sheet for can end with excellent performance. 4. A method of baking the aluminum alloy sheet according to claim 3 or laminating the sheet with a thermoplastic resin, heating the sheet material to 200 to 300 ° C., and performing score processing using the sheet material. The method for producing an aluminum alloy plate for a can end having excellent blow-up resistance according to claim 3.