JP2001032057A - Production of aluminum alloy sheet for can end excellent in blowup resistance - Google Patents

Abstract

PROBLEM TO BE SOLVED: To impart excellent blowup resistance to an alloy sheet by casting a sheet material from the molten metal of an Al alloy having a specified compsn. and successively subjecting the sheet to cold rolling, primary process annealing, cold rolling, secondary process annealing and final cold rolling at specified temps. and speeds. SOLUTION: The molten metal of an Al alloy composed of, by weight, 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 is continuously cast into a sheet material of 3 to 8 mm thickness at a solidifying rate of >=100 deg.C/sec. Directly, or after cold rolling, it is subjected to primary process annealing of executing heating at 500 to 590 deg.C for >=1 hr, is cold-rolled, is subjected to secondary process annealing of executing heating at 480 to 590 deg.C at a temp. rising rate of >=10 deg.C/sec and, without holding or holding within 30 sec, executing cooling to <=100 deg.C at a cooling rate of >=10 deg.C/sec and is subjected to final cold rolling of 40 to 75%. In this operation, the primary process annealing is executed by a batch type annealing furnace, and the secondary process annealing is executed by a continuos annealing furnace.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing an aluminum alloy plate for a can end (end) of a beverage can or the like, which is excellent in recyclability and has various properties such as strength, corrosion resistance and moldability. At the same time as having the characteristics, even if the end is in an inverted state called buckling due to the internal pressure, in particular, no crack is generated in the end, and there is no possibility that the contents will blow out from the end, that is,
The present invention relates to an improved technique of a method for producing an aluminum alloy plate for a can end such as a beverage having excellent blow-up resistance.

[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, the end material of the 5182 alloy also has a problem in that the pressure resistance decreases due to aging softening over time after molding, and the endurance may fall below a required value.

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. 4 shows this state. The end 2 is attached to the opening of the body 1, and the periphery of the end 2 is wound around 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 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. 5, the end 2 swells to the outside as shown in FIG. 6 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 a method for producing an aluminum alloy plate for a can end which is excellent in l-Mn-based blow-up resistance.

[0014]

SUMMARY OF THE INVENTION From the above-mentioned viewpoints, the present inventors have conducted research to develop Al-Mn alloys for beverage can ends having excellent blow-up resistance. DC casting method (Direct Chill Casti
ng Process: Casting method in which molten metal is introduced into a water-cooled mold and cast) Al-Mn-based aluminum alloy end materials produced from ingots contain coarse intermetallic compounds such as Al-Fe-Mn, From this, it has been found that fine cracks are apt to occur at the time of score processing, and in this case, if a high internal pressure acts, blow-up is likely to occur. In addition, as a result of further research, the continuous casting and rolling method with a high solidification rate was used instead of the conventional general DC casting method to refine the Al-Fe-Mn intermetallic compound and to perform appropriate processing and heat treatment. It has been found that by applying the process, blow-up can be suppressed, and the present invention has been achieved. Further, they have found that a sufficient pressure resistance can be obtained by coating the obtained aluminum alloy plate or laminating it with a thermoplastic resin film and setting the proof stress to 300 MPa or more, and reached the present invention.

In order to solve the above problems, the production method of the present invention comprises: 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%,
After casting from a melt of an aluminum alloy having a composition of residual Al and unavoidable impurities into a sheet having a thickness of 3 to 8 mm by a continuous casting and rolling method at a solidification rate of 100 ° C./sec or more, and then immediately or after cold rolling , A first intermediate annealing in a temperature range of 500 to 590 ° C. for 1 hour or more, followed by a cold rolling, followed by heating to a temperature range of 480 to 590 ° C. at a rate of 10 ° C./sec or more. No holding time,
Alternatively, after holding for 30 seconds or less, secondary intermediate annealing is performed at a cooling rate of 10 ° C./sec or more to a temperature of 100 ° C. or less, and final cold rolling of 40 to 75% is further performed.

Further, the manufacturing method of the present invention is characterized in that the primary intermediate annealing is performed in a batch type annealing furnace, and the secondary intermediate annealing is performed in a continuous annealing furnace.

Further, in the production method of the present invention, the plate is heated to 200 to 300 ° C. by baking after final cold rolling, or laminated with a thermoplastic resin, and score processing is performed using the plate. It is characterized by.

Hereinafter, the reason why the alloy composition and the production method in the present invention are limited as described above will be described. "Mn": Mn has an effect of increasing strength, but if its content exceeds 1.5% (% by weight, the same applies hereinafter), it becomes coarse with Al, Fe, Si, etc. at the center of a continuously cast and rolled plate. An intermetallic compound is formed, the moldability is reduced, and fine cracks originating from the intermetallic compound are easily generated during scoring, and blow-up is easily generated. On the other hand, if the content of Mn is less than 0.6%, the desired effect of improving the strength as the 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 has the effect of improving the strength by precipitating as a u-Mg-based compound. However, 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, Corrosion resistance may be significantly reduced.

"Fe": Fe easily forms a coarse intermetallic compound with Al, Mn, Si, etc., and reduces the formability.
Fine cracks are easily generated during score processing, and blow-up is easily generated. 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. If the content of Fe exceeds 0.5%, coarse A
An l-Fe-Mn intermetallic compound (for example, a particle size exceeding 1 µm) is generated.

"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.

[0023]

Embodiments of the present invention will be described below in detail. In order to manufacture an aluminum alloy plate having the above composition, for example, from an alloy melt having the above composition, 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,
Thicknesses of about 3 to 8 mm can be produced directly from the molten metal.

The cooling rate in the continuous casting and rolling method is as follows:
It can be much faster than a general DC casting method (0.5 to 40 ° C./sec in cooling rate) in which a normal ingot is cast into a mold, and a cooling rate of 100 to 300 ° C./sec. It can be. If the cast plate 9 is cast in such a high cooling rate range, the particle size of the Al—Fe—Mn intermetallic compound and Mg ₂ Si intermetallic compound generated in the metal structure in the Al alloy having the above-described composition. Can be made finer than in the case of a general conventional DC casting method. Starting from such a cast plate 9, if the aluminum alloy plate for end is formed by the following manufacturing process, the particle size of the intermetallic compound present in the structure is sufficiently fine so as not to cause blow-up. Can be reliably achieved. For example, the average particle diameter of the intermetallic compound can be 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. When manufacturing the cast plate 9, according to the ordinary DC casting method in which the cooling rate is in the range of 0.5 to 40 ° C./sec, the particle size of the intermetallic compound is reduced even if the following steps are performed. It is difficult to miniaturize.

As for the method of continuous casting and rolling of the molten alloy, any of the 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.

With respect to the cast plate thus obtained,
Immediately or after cold rolling, 500-590
The primary intermediate annealing of heating in a temperature range of ° C. for 1 hour or more is performed in a batch type annealing furnace. The batch type annealing furnace has an atmosphere adjusting furnace for accommodating a plate-shaped long member to be annealed wound in a coil shape, and the atmosphere is adjusted until the target temperature is reached after storing the coil in the atmosphere adjusting furnace. This is an annealing furnace that can heat the inside of the conditioning furnace to a target temperature, and has been widely used in the past. It is preferable that the annealing furnace is connected to a gas supply source or the like so that the inside can be adjusted to a desired atmosphere such as an inert gas atmosphere as needed.

If the primary intermediate annealing temperature is less than 500 ° C. or the primary intermediate annealing time is less than 1 hour, Mg segregated at the grain boundaries cannot be sufficiently diffused into the grains, and The Mg ₂ Si compound crystallized at the boundary cannot be dissolved sufficiently, so that the blow-up resistance is reduced and side cracks are liable to occur during the subsequent cold rolling.

Subsequently, after cold rolling, the material is heated to a temperature range of 480 to 590 ° C. at a temperature rising rate of 10 ° C./sec or more and has no holding time (zero holding time), or within 30 seconds. After the holding, the secondary intermediate annealing is cooled to a temperature of 100 ° C or less at a cooling rate of 10 ° C / sec or more.
ntinuous Annealing Line: CAL).

FIG. 3 shows the structure of an example of the rapid continuous heat treatment furnace described above.
Horizontally elongated heating furnace body 20 having a length of about 0 m to 110 m
And shock absorbers 21 and 22 disposed on the front and rear sides of the heating furnace main body 20, respectively, a delivery roll 23 provided on the front side of the front shock absorber 21 and a rear shock absorber 22. It is mainly constituted by a take-up roll 25 provided at the subsequent stage. The shock absorbers 21 and 22 are individually provided with a plurality of guide rolls 26...
... to eliminate the need to stop the line when replacing the coil. The rapid continuous heat treatment furnace A shown in FIG. 3 is one example, and it goes without saying that a furnace incorporating other necessary equipment may be used.

The annealing temperature in the rapid continuous heat treatment furnace is 48
If the temperature is less than 0 ° C. or the cooling rate is less than 10 ° C./sec, M
g, Si, and Cu cannot be dissolved sufficiently, and a desired strength cannot be obtained in the finally obtained aluminum alloy plate for end. On the other hand, if the annealing time exceeds 30 seconds, the crystal grains become coarse and the formability of the aluminum alloy sheet for end is reduced.

Further, a final cold rolling of 40 to 75% is performed. If the rolling reduction is less than 40%, a desired strength cannot be obtained in the finally obtained aluminum alloy sheet for end, while the rolling reduction is reduced. If it exceeds 75%, the difference between the tensile strength and the proof stress decreases, and the blow-up resistance decreases. Even in the range of the processing rate, a processing rate in the range of 45 to 60% is more preferable. The thickness of the aluminum alloy sheet for can end after the final cold rolling may be 0.31 mm thick, 0.28 mm thick, or the like.

The final rolled sheet obtained in the above steps is subjected to a surface treatment such as a chromate treatment, followed by baking coating or lamination with a thermoplastic resin film such as PET (polyethylene terephthalate) 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, 200 to 28
A process of heating at 0 ° C. for 3 to 60 seconds is performed. An aluminum alloy plate having the above composition, which is baked or laminated with a thermoplastic resin film such as PET (polyethylene terephthalate) and has a proof stress of 3
It is preferable that the pressure is not less than 00 MPa.

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

The aluminum alloy plate obtained by the above-described manufacturing method is an aluminum alloy plate having Mn, Mg, Si, Cu, Fe, and Ti in appropriate contents.
In addition, the average particle size of the intermetallic compound is reduced (for example, 1 μm or less) under the manufacturing conditions including the above-mentioned appropriate batch-type primary intermediate annealing and the secondary intermediate annealing in the rapid continuous annealing furnace.
Therefore, it is possible to prevent blow-up caused by an increase in internal pressure, which is a problem particularly when the beverage can is used. Next, in the finally obtained aluminum alloy plate, the average particle diameter of the intermetallic compound is preferably 1 μm or less. If the average particle size of the intermetallic compound exceeds 1 μm, fine cracks are likely to occur at the time of scoring starting from the intermetallic compound, and blow-up may easily occur when a high internal pressure is applied. . As intermetallic compounds herein can be exemplified by Al-Fe-Mn-based intermetallic compounds and Mg ₂ Si-based intermetallic compounds.

That is, among the additional elements, Fe and Mn
Is likely to produce an Al-Fe-Mn coarse intermetallic compound (for example, having a particle size of more than 1 μm) together with Al. If the average particle size of this coarse intermetallic compound is set to a value exceeding 1 μm, In such a case, if a cut is made by score processing to constitute a drinking can of a beverage can, a fine crack may be generated starting from the intermetallic compound, but the primary intermediate annealing is performed as the composition range. By producing under appropriate conditions including secondary annealing and secondary intermediate annealing, coarse intermetallic compounds having an average particle size of more than 1 μm can be reduced, and generation of fine cracks during score processing can be suppressed.

Therefore, when the end of a beverage can is constituted by using the aluminum alloy plate according to the present invention, or when the internal pressure is increased by leaving the beverage can in a high-temperature automobile in summer, the beverage can is caused by any cause. Even if the internal pressure of the sample rises abnormally, blow-up does not occur from a fine crack as a starting point, and there is no possibility that the contents are 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.

[0038]

EXAMPLES Aluminum alloys having the respective compositions shown in Nos. 1 to 16 in Table 1 below were cast into plates having a thickness of 5 mm by a continuous casting and rolling method at a solidification rate of 150 ° C./sec. Next, these cast plates were placed in a batch type annealing furnace at 500 ° C. to 550 ° C.
4 hours primary intermediate annealing, then 0.62m thick
m, and 500 to 550 at a rate of 15 ° C./sec.
After heating to 0 ° C., a second intermediate annealing treatment of rapidly cooling after holding for 0 to 10 seconds was performed, and an end aluminum alloy plate having a thickness of 0.31 mm was obtained by final cold rolling. Table 1
No. 15 sample was cast by DC casting (solidification rate 10 ° C /
Second). After homogenizing at 565 ° C. for 8 hours, hot rolling was performed to a thickness of 7 mm. Then, 0.62mm in thickness
Cold-rolled until the same processing as the samples of Nos. 1 to 14 was performed.

Next, a resin film of polyethylene terephthalate (PET) having a thickness of 12 μm was laminated,
Heat treatment was performed at 60 ° C. for 20 seconds to strengthen the adhesion of the resin film. As a comparative example, a laminated plate was manufactured by a process in which the primary intermediate annealing, the secondary intermediate annealing, and the final cold rolling rate of the same cast plate were set outside the present invention. Finally, these laminates are scored to form a notch with a depth of 2/3 of that of the aluminum alloy plate to form a drinking spout by a press device, and a tab for cutting and raising is attached to serve as a can end. it can.

"Table 1" Sample No. Si Fe Cu Mn Mg Zn Ti 1 0.28 0.18 0.35 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 0.43 0.20 0.99 2.00 0.08 0.02 12 0.29 0.43 0.20 0.99 2.00 0.08 0.02 13 0.29 0.43 0.20 0.99 2.00 0.08 0.02 14 0.29 0.43 0.20 0.99 2.00 0.08 0.02 15 0.29 0.43 0.40 0.99 2.00 0.08 0.02

[Table 2] Sample Primary intermediate intermediate annealing Secondary heating Secondary intermediate Final cold pressure No. Annealing condition Sheet thickness (mm) speed (° C / S) Annealing condition Rolling rate (%) 1500 ° C × 4h 0.62 15 550 ° C. × 0s 50 2 550 ° C. × 4h 0.62 15 550 ° C. × 10s 50 3 500 ° C. × 4h 0.62 15 550 ° C. × 0s 50 4 550 ° C. × 4h 0.62 15 550 ° C. 10s 505 500 ° C x 4h 0.62 15 500 ° C x 0s 506 500 ° C x 4h 0.62 15 500 ° C x 0s 507 500 ° C x 4h 0.62 15 500 ° C x 0s 508 500 ° C x 4h0 .62 15 500 ° C x 0s 509 500 ° C x 4h 0.62 15 500 ° C x 0s 50 10 450 ° C x 4h 0.62 15 520 ° C x 0s 5011 550 ° C x 0.5h 0.62 15 550 ° C x 0s 50 12 5 00 ° C × 4h 0.627 500 ° C. × 0s 50 13 500 ° C. × 4h 0.62 15 450 ° C. × 0s 50 14 500 ° C. × 4h 0.62 15 550 ° C. × 180s 50 15-1.0015 550 ° C. × 0s 69

[Table 3] Sample No. Tensile strength Yield strength Elongation AB (MPa) (MPa) (%) (%) (%) 1 371 325 7.5 100 0 2 347 302 6.4 100 0 3 357 309 7.3 100 0 4 350 305 5.9 100 0 5 364 314 8.0 100 0 6 371 325 8.2 40 60 7 370 323 5.8 5.8 20 80 8 345 297 6.0 100 0 9 375 329 7.7 60 40 10 365 314 5.6 40 60 11 368 315 5.5 60 40 12 346 294 5.7 100 0 13 339 291 5.8 100 0 14 354 308 6.2 60 40 15 362 320 5.5 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 3, 4, and 5 exhibited proof stress in the range of 305 to 325 MPa (proof strength equivalent to that of the 5182 alloy). Also,
As a result of measuring the average particle diameter of the intermetallic compound formed in each sample, it was found that each was 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,
The sample of No. 6 was a sample whose Fe content was increased to 0.6%, but was blown up. The sample of No. 7 contained Cu in an amount of 0.
Although the sample was increased to 43%, this sample was also blown up. The sample of No. 8 was a sample in which Mn was reduced, but the blow-up was not performed, but the tensile strength and the proof stress were reduced. The sample of No. 9 was a sample to which a large amount of Mn was added, but 40% of the samples blown up. The sample of No. 10 was a sample in which the first intermediate annealing temperature was 450 ° C.
0% of the sample blown up. The sample of No. 11 was a sample in which the first intermediate annealing time was 0.5 h, but blow-up occurred in 40% of the samples. The sample of No. 12 is a sample in which the temperature rise rate of the second intermediate annealing is 7 ° C./S, but the proof stress is 30
The value fell below 0 MPa (294 MPa). N
The sample No. o.13 was a sample in which the second intermediate annealing temperature was lowered to 450 ° C., but the yield strength was less than 300 MPa (291).
MPa). The sample of No. 14 was a sample in which the second intermediate annealing holding time was increased to 180 seconds, but 40% of the samples were blown up. Next, although the sample of No. 15 manufactured by the DC casting method was in a preferable range in terms of the alloy composition, the average particle diameter of the intermetallic compound was significantly large, and 60% of the samples were blown up. From the above, the samples of Nos. 1 to 5 having the composition according to the present invention and produced by performing the first intermediate annealing and the second intermediate annealing under the conditions of the present invention have excellent blow-up resistance. And showed excellent tensile strength, proof stress and elongation. On the other hand, it is clear that the samples of Nos. 6 to 9 out of the composition range of the present invention cause blow-up or are inferior in tensile strength and proof stress,
It is clear that the samples Nos. 10 to 15 out of the production conditions of the present invention cause blow-up or have poor tensile strength and proof stress.

[0045]

As described above, the method for manufacturing an aluminum alloy sheet according to the present invention comprises the steps of: Mn, Mg, Si, Cu, Fe
Aluminum alloy by continuous casting and rolling, first intermediate annealing under appropriate conditions, second intermediate annealing under appropriate conditions, and final cold rolling from molten aluminum alloy with proper contents of Ti and Ti In order to obtain a plate, among the additive elements, the amount of Fe and Mn to produce a coarse intermetallic compound such as an Al-Fe-Mn system is produced under the condition that these contents are not coarsened as appropriate contents. An aluminum alloy plate for a can end having a microstructure of an intermetallic compound that is easily coarsened can be obtained.

When such an intermetallic compound is coarsened, when the cut is made by scoring to form a drinking can of a beverage can, the intermetallic compound is used as a starting point. There is a possibility that a fine crack may be generated, but by setting the addition amount of the element in an appropriate range and processing under appropriate conditions, the intermetallic compound can be refined, and the generation of a fine crack at the time of score processing can be reduced. Can be suppressed. Therefore, when the end of a beverage can is manufactured using the aluminum alloy plate obtained according to the present invention, or when the internal pressure is abnormally increased by leaving the beverage can in a high-temperature automobile in summer, the beverage can be caused by any cause. Even if the internal pressure of the can is abnormally increased, it is possible to provide a beverage can that does not cause blow-up from a fine crack as a starting point and does not have a possibility of blowing out the contents.

If an aluminum alloy sheet having the composition according to the present invention is used, it has the same strength as the 5182 alloy used as a conventional end material, and also has excellent blow-up resistance as described above. Further, if the aluminum alloy plate of the present invention is used, Mg is 4 to 5%.
% Compared to 5182 alloy containing less Mg, and Mn content higher than 5182 alloy
Since it is a composition system similar to the -Mn system, there is an effect that it has a characteristic excellent in recyclability.

[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 configuration diagram showing a continuous annealing furnace used when performing an example of the method of the present invention.

FIG. 4 is a cross-sectional view showing an example of a joint portion between a body and an end of a general aluminum can.

FIG. 5 is a sectional view showing a state in which buckling is caused by deformation of an end material in a general aluminum can.

FIG. 6 is a cross-sectional view showing a state in which an end material has swelled in a general aluminum can.

[Explanation of symbols]

A: Rapid continuous annealing furnace, 1 ... (can) body, 2 ... (can)
End, 2a: counter sink, 2b: circumferential groove, 2d
... partial, 5, 6 ... roll, 7 ... feeder chip, 8 ... melt, 9 ... primary plate, 20 ... heating furnace body.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C22F 1/00 686 C22F 1/00 686B 693 693A 693B 693Z 694 694A

Claims (3)

[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 melt containing 0.001 to 0.2%, having a balance of Al and unavoidable impurities, is cast into a sheet having a thickness of 3 to 8 mm by a continuous casting and rolling method at a solidification rate of 100 ° C./sec or more, Then, immediately or after cold rolling, a first intermediate annealing is performed in a temperature range of 500 to 590 ° C. for 1 hour or more, followed by cold rolling.
Heat to a temperature range of 480 to 590 ° C. at a temperature rising rate of 0 ° C./sec or more and hold for no holding time, or after holding for 30 seconds or less, cool to a temperature of 100 ° C. or less at a cooling rate of 10 ° C./sec or more A method for producing an aluminum alloy sheet for a can end having excellent blow-up resistance, which comprises performing a secondary intermediate annealing and further performing a final cold rolling of 40 to 75%. 2. The aluminum for can ends having excellent blow-up resistance according to claim 1, wherein the primary intermediate annealing is performed in a batch type annealing furnace, and the secondary intermediate annealing is performed in a continuous annealing furnace. Manufacturing method of alloy sheet. 3. A baking coating after the final cold rolling,
Alternatively, by laminating with a thermoplastic resin,
The method for producing an aluminum alloy sheet for a can end having excellent blow-up resistance according to claim 1 or 2, wherein the sheet material is heated to about 300 ° C and score processing is performed using the sheet material.