JPH05263175A - Aluminum alloy sheet for stay-on tab - Google Patents

Abstract

PURPOSE:To provide an aluminum alloy sheet for a stay-on tab satisfying strength and bendability required in the stay-on tab material of a can of beer, carbonated drinks or the like and small in secular softening after tab forming. CONSTITUTION:The objective alloy sheet contains, by weight, 1 to 3% Mg and 0.005 to 0.20% Ti for the refining and stabilizing of the structure independently or in combination with 0.0005 to 0.04% B, furthermore contains one or >=two kinds among 0.01 to 0.6% Fe, 0.1 to 1.2% Mn, 0.05 to 0.5% Si, 0.05 to 0.5% Cu, 0.05 to 0.03 Cr and 0.1 to 0.5% Zn, among which at least either of Fe and Mn should be contained as well as Fe+Mn<=1.6% is satisfied, and the balance Al with inevitable impurities. Its secular softening occurs at >=250N/mm<2> proof stress.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tab material for beer cans, carbonated drinks cans, and the like. More specifically, it has the same strength and bendability as those of the current materials, and is a Steion tab which is less softened by aging. The present invention relates to a tab material for an attached end.

[0002]

2. Description of the Related Art At present, as a method of opening a beverage can such as a beer can or a carbonated beverage can, an easy open end, which can be easily opened by hand without using a device such as a can opener, is predominant. This easy open end includes partial open end and full open end where the tab separates from the can at the time of opening, and Steion tab end and push-on tab end where the tab does not separate from the can during opening. Ends with tabs are widely used especially in Europe and the United States from the viewpoints of environmental problems such as tabs not separating and resource recycling. The tab material suitable for this end with the Steion tab is M such as AA5082 and AA5042.
An aluminum alloy containing around g4.0 is used, and the aluminum alloy ingot is subjected to soaking treatment and hot rolling, followed by cold rolling at a high pressure reduction rate, and then strength is adjusted by final heat treatment. It is manufactured by the manufacturing method. For example, as disclosed in US Pat. No. 3,502,448, it is a method of increasing the finish cold rolling rate to 85% or more. After this step, the tab material is subjected to final heat treatment for strength adjustment and stabilization.

[0003]

Since the aluminum alloy used in the conventional stion tab material has a relatively large amount of Mg added and is subjected to high cold rolling, strength adjustment and stabilization are performed by the final heat treatment. Has been done. However, since the final heat treatment is performed at a relatively high temperature (about 280 ° C.), a degreasing treatment is necessary as a pretreatment for the purpose of preventing seizure of rolling oil. Further, since the range of the finish annealing temperature is narrow, the accuracy of the annealing temperature is important, and the annealing equipment is required to have high accuracy such as temperature control. Furthermore, in the state after being formed into tabs, since it has undergone processing and hardening after the stabilization treatment, dislocations newly generated in the processed part cause precipitation of beta phase, etc. due to aging, and this causes solidification. The phenomenon that the amount of dissolved Mg decreases and the strength softens occurs. As a result, with a mechanism such as the Stein tab that opens the score portion by the principle of pulling, the tab strength is insufficient and there is a problem of poor opening. As a countermeasure for this, it is necessary to increase the thickness of the tab material or increase the initial strength to an unnecessary degree, but as a result, the manufacturing cost and material cost are higher than the tab material for partial open end,
One of the factors is that it is not adopted so much in Japan and is not widely used, despite the fact that malfunctions tend to occur and the end with Stein tab is certainly more advantageous in terms of can pollution. Is becoming As another method of preventing softening with time, a method of reducing the amount of added Mg can be considered. However, in recent years, with the thinning of the Steion tab, relatively high strength has become one of the important characteristics as the Steion tab material.
The strength of the conventional manufacturing method is not sufficient by simply reducing the amount of Mg added to the conventional alloy, and high cold rolling is required to obtain the required strength. As a result, there is a problem in formability, especially bending workability. Occurs. The present invention has been made under such circumstances, and in particular, aluminum for a Stein tab, which is required for a molding process in which the moldability and the strength are kept at the conventional level and the softening with time is small. It is intended to provide an alloy plate.

[0004]

In order to achieve the above-mentioned object, the present inventors have adjusted the chemical composition so that bending composition and strength can be obtained in the same composition as conventional materials with a composition that does not soften with time. We conducted comprehensive research on the organization and manufacturing conditions. As a result, it was found that the desired material properties could be obtained if the composition control including Mg, the structure, and the manufacturing conditions were regulated.

That is, in terms of alloy composition, the conventional aluminum alloys 5082 and 5182 for a stab tab are Mg.
In the present invention, the addition amount of Mg is 4 to 5% and 5042 is 3 to 4%, whereas in the present invention, the softening with time is reduced and the strength is supplemented by reducing the addition amount of Mg to 3% or less. In addition to controlling the amount of Mn, Si, Cu and Cr added, the dispersion and size of the crystallized compound due to Fe and Mn can be prevented to prevent deterioration of bendability, and a casting method depending on the composition of the additive element, It has been found that by selecting the homogenization treatment temperature, the cold rolling rate and the finishing heat treatment method, it is possible to obtain a material that can obtain the required strength and is not inferior in terms of bendability.

That is, according to the present invention, as in claim 1, Mg: 1 to 3% and Ti: 0.005 to 0.20% alone or B: Included with 0.0005 to 0.04%, Fe: 0.01 to 0.6%, Mn: 0.1 to 1.2
%, Si: 0.05 to 0.5%, Cu: 0.05 to 0.
5%, Cr: 0.05 to 0.3%, Zn: 0.1 to 0.
One or more of 5% is included, of which Fe
And Mn always include at least one of them and F
It is an aluminum alloy plate for a steion tab having e + Mn ≦ 1.6% or less, the balance consisting of Al and unavoidable impurities, and a yield strength of 250 N / mm ² or more, which is hard to soften with time.

[0007]

The present invention will be described in more detail below. First, the reasons for limiting the chemical components in the present invention will be described. Mg: Mg is an important element that imparts strength, and it is necessary to secure a strength that can be used as a steion tab material by adding a predetermined amount. However, when the content exceeds 3%, dislocations in the worked portion cause precipitation of a beta phase and the like due to a change with time, so that the amount of solid solution Mg decreases and the strength is softened, so that softening with time easily occurs. On the other hand, if it is less than 1%, the strength which is insufficient with other additive elements cannot be supplemented. Therefore, the amount of Mg should be in the range of 1 to 3%. Ti, B: Ti, B is an effective element for refining and stabilizing the structure. However, if the addition amount is small, there is no effect, and if the addition amount is large, a huge compound is formed and bending workability is deteriorated. Therefore, 0.005 to 0.20% Ti alone or B is added.
Add with 0.0005-0.04%. Si: Addition of Si contributes to strength improvement by age hardening due to generation of Mg ₂ Si. If it is less than 0.05%, there is no effect, and if it exceeds 0.5%, although it contributes to the improvement of strength, it is excessively hardened to deteriorate the moldability. Therefore,
The amount of Si shall be 0.05 to 0.5%. Cu: Cu addition contributes to strength improvement by age hardening by age precipitation of Al-Cu-Mg. But 0.05
If it is less than 0.5%, the effect is small, and if it is added in excess of 0.5%, the strength becomes too high, resulting in deterioration of moldability. Therefore, the amount of Cu is set to the range of 0.05 to 0.5%. The addition of Zn: Zn is expected to improve strength by aging precipitation of Mg ₂ Zn ₃ Al ₂ , but if it is less than 0.1%, there is no effect, and if it exceeds 0.5%, there is no problem with the contribution of strength.
Corrosion resistance deteriorates, so it is necessary to regulate below this value. Therefore, the Zn amount is set to the range of 0.1 to 0.5%. When the strength is supplemented by the addition of Si, Cu and Zn as described above, it is preferable to use a method such as CAL in which intermediate annealing has a solution treatment effect by rapid heating and cooling at high temperature. Addition of Mn: Mn has a great effect on strength improvement. However, when Mn is less than 0.1%, the effect is small and 1.2
If it exceeds%, the size of the crystallized product becomes large, and the number of crystallized products becomes large, resulting in a decrease in bendability, which is not preferable. Therefore, the Mn content is set to the range of 0.1 to 1.2%. Cr: Addition of Cr has a great effect on the strength improvement. Cr
Is less than 0.05%, there is no such effect, and if it is added in excess of 0.3%, a large crystallized product is formed, resulting in a decrease in bendability, which is not preferable. Therefore, the Cr amount is set to the range of 0.05 to 0.3%. Fe: Addition of Fe is effective in improving strength. But F
If the content of e is less than 0.01%, there is no effect, and if it exceeds 0.6%, the size of the crystallized product is large, and the number is increased, resulting in a decrease in bendability. Therefore, Fe
The amount is in the range of 0.01 to 0.6%. Also Mn and Fe
And Fe have the effects of reducing bendability, so Fe and M
It is necessary to regulate even the total amount of n, and Fe + Mn ≦ 1.6
%. If it is up to 1.6%, the bendability is not adversely affected by selecting a casting method with a high solidification rate (for example, a continuous casting and rolling method at 50 ° C./s or more). In addition, in the present invention, Mg and Ti and / or B for refining and stabilizing the structure are indispensable, but the elements (Si, Cu, Zn, Mn and Cr, F) necessary for obtaining the strength are required.
e) is a selective addition element, and at least one of them is added as necessary, and in particular, for Fe and Mn, either one is always added. If the content of each element other than the above contained in the Al alloy is less than 0.05%, the effect of the present invention is not impaired. In particular, Zr and V are effective for stabilizing the structure up to 0.3%.

The manufacturing method suitable for the aluminum alloy sheet of the present invention will be described. As for the Al alloy having the above-mentioned chemical components, the manufacturing method affects the strengthening mechanism and the size of the crystallized substance, so that it is desirable to appropriately select the manufacturing method depending on the components (especially Fe + Mn amount) of each alloy. The main manufacturing methods that can be adopted in the present invention are listed below. DC casting Cooling rate about 10 ° C / s (1) DC casting → heating → hot rolling → intermediate annealing (CAL)
→ Cold rolling → Heat treatment (2) DC casting → Heating → Hot rolling → Cold rolling → Intermediate annealing (CA
L) → cold rolling → heat treatment (3) DC casting → heating → hot rolling → cold rolling → intermediate annealing (batch) → cold rolling → heat treatment continuous casting and rolling (hereinafter abbreviated as CC) cooling rate 50 ° C / s
Above (4) CC → cold rolling → intermediate annealing (CA
L) → cold rolling → heat treatment (5) CC → heating → cold rolling → intermediate annealing (CA
L) → cold rolling → heat treatment (6) CC → heating → cold rolling → intermediate annealing (batch) → cold rolling → heat treatment (7) CC → cold rolling → heating → cold rolling → intermediate annealing (CA)
L) → Cold rolling → Heat treatment (8) CC → Cold rolling → Heating → Cold rolling → Intermediate annealing (batch) → Cold rolling → Heat treatment Among the above manufacturing methods, the optimum manufacturing method according to the amount of Fe + Mn will be described below. a. Fe + Mn <0.7% Within this range, the bendability due to the crystallized material is less deteriorated regardless of which casting method is selected. Therefore, the strength increase by the final cold rolling rate can be allowed up to about 90%. However, the required strength cannot be obtained unless the final cold rolling rate is 30% or more.
However, since strengthening by Mn cannot be expected, it is indispensable to adopt CAL which has a solution treatment effect during the intermediate annealing in order to improve the strength. Therefore, the manufacturing methods 2, 4, 5, and 7 are desirable. Further, the manufacturing methods 4, 5 and 7 in which CCs having a high cooling rate and capable of expecting a solid solution during casting are combined are more preferable. b. 0.5% <Fe + Mn <1.2% Since the crystallized compound affects the bendability, heat treatment for homogenization is essential. Therefore, the manufacturing methods 1, 2, 3, 5,
6, 7 and 8 are desirable. Further, strength improvement by Mn can be expected, and even if batch type intermediate annealing is used by combining with other additive elements, required strength can be obtained within the final cold rolling rate at which bendability is allowed. However, in the case of this composition range, when the final cold rolling rate increases, dislocations preferentially accumulate around the crystallized compound, which easily becomes a base point of cracking during bending. Further, this is also affected by the size of the crystallized product, and the larger the size, the larger the dislocation segregation and the worse the bendability. In the case of DC material: Since the crystallized material has an average diameter of 3 μm or more, the final cold rolling rate is preferably 80% or less. In the case of CC material: Since the crystallized material has an average diameter of 2 μm or less, the final cold rolling rate is acceptable up to 90%. The required strength cannot be obtained unless the final cold rolling rate is 30% or more. c. 1 <Fe + Mn ≦ 1.6% In this composition range, coarse crystallized substances increase in DC casting. Specifically, 100 / 0.2 mm ² or more of crystallized substances having a size of 5 μm or more are generated on the plate surface. In such dispersion of crystallized substances, even if the reduction ratio is reduced, cracking occurs during bending work together with dislocations added during bending work. Therefore, CC is essential for the casting method. In addition, heat treatment is indispensable for spheroidizing and dispersing the crystallized substance. The CC material is heated (the heating temperature is the same as in the case of b.) To spheroidize and disperse the crystallized substances between the dendrite dendrites, and 10 particles of 5 μm or more / 0.2 mm
Fine crystallized substances less than ² can be dispersed randomly. However, in this case, there are 200 crystallized substances of 1 μm or more.
Since the number is 0 pieces / 0.2 mm ² or more, the final cold rolling rate is 80
% Or less is desirable. However, the required strength cannot be obtained unless the final cold rolling rate is 30% or more. In this case, since Mn, which makes a large contribution to the strength, is also sufficiently added, the intermediate annealing may be CAL or batch. Therefore, the manufacturing method 5,
6, 7 and 8 are desirable. In the range of 0.5 to 0.7% and 1.0 to 1.2% in which Fe + Mn spans each of the above-mentioned categories, the manufacturing method is not determined centrally by Fe + Mn alone, and Mn is Mn.
Either manufacturing method is possible depending on the amount of strengthening components other than the above, the cold rolling ratio, and the intermediate annealing method. Fe + Mn> 1.6%
However, by adopting CC as a casting method, it is possible to reduce the size of crystallized substances to less than 3 μm, but the number of 1 μm or more is greater than 4000 / mm ² , and dislocations are less accumulated in each crystallized substance. Since the distance between the crystallized substance particles is shortened, dislocations are accumulated around the plurality of crystallized substances, and it acts as if there is one coarse crystallized substance particle.
Therefore, Fe + Mn ≦ 1.6% or less.

Among the above manufacturing methods, common process conditions are described below. Heating: A temperature of 500 ° C. or higher is required and it is better that the temperature is high, but the maximum temperature is determined by the amount of Mg added,
g wt% +655) ° C., and eutectic melting occurs above this. Intermediate annealing CAL: heating rate / cooling rate is 1 ° C./s or more, ultimate temperature is 380 to 600 ° C., and holding time is 0 to 10 minutes. Batch: heating rate / cooling rate is 10-100 ° C / Hr,
The ultimate temperature is 300 to 500 ° C. and the holding time is 30 minutes or longer. Final heat treatment batch: If the reached temperature does not reach 100 ° C or higher, dislocation recovery does not proceed and the material becomes brittle and the bendability deteriorates. But 250 ℃
If it exceeds, strength control is difficult. Therefore, the temperature range is 100
~ 250 ° C. Hold time should be 5 minutes or more,
Because the effect does not change even if it is heat-treated for too long, 1
0 hours or less is good. The final heat treatment includes not only the treatment by the batch furnace in the rolling plate manufacturing process in the case of no coating but also the coating baking treatment in the batch type coating line in the case of coating, which is included in the final heat treatment. CAL: Since the holding time is short, the dislocation recovery does not proceed and the material is brittle and the bendability is poor unless the ultimate temperature is 200 ° C. or higher. However, if it exceeds 350 ° C., strength control is difficult near the recrystallization temperature. Therefore, the ultimate temperature is set to 200 to 350 ° C. In addition, the holding time is 0 to 0 due to the facility features of the continuous processing equipment.
5 minutes is preferred. In addition, not only the treatment by CAL in the rolled plate manufacturing process in the case of no coating but also the continuous heat treatment such as coating baking in the continuous coating line in the case of coating is included in the final heat treatment.

If the yield strength of the base plate is less than 250 N / mm ² ,
At the stage of one year after tab formation, the strength of the tab becomes insufficient due to softening over time, and when the can is opened, the tab bends and causes a can opening failure. To prevent this, it is necessary to use a tab material having an increased plate thickness, resulting in an increase in cost.
Therefore, it is necessary that the yield strength of the base plate is 250 N / mm ² or more.

Further, the aluminum alloy for a steion tab is required not only to have a high yield strength immediately after molding but also to be resistant to softening with time. In the present invention, the amount of softening with time is preferably less than 50 N / mm ² between the proof stress after tab molding and the proof stress after one year of standing at room temperature (hereinafter referred to as the proof stress difference). If a proof stress difference of 50 N / mm ² or more occurs, even if the strength immediately after molding is strong, the strength gradually becomes insufficient due to softening over time, and the mechanism of prying the score part on the principle of leverage like the Stein tab causes the tab to open when opening. It bends and causes poor opening.

[0012]

EXAMPLES Examples of the present invention will be described below. Table 1 shows the alloy composition of the aluminum alloy used in the examples. Here, A, B, and C are in the respective composition ranges described above in the manufacturing method, A is Fe + Mn <0.7%, and B is 0.
5% <Fe + Mn <1.2%, C is 1 <Fe + Mn ≦
It satisfies the condition of 1.6%. Further, D corresponds to the conventional alloy 5182. Further, E is out of the condition of the present invention, Fe + Mn ≦ 1.6%.

[0013]

[Table 1]

Table 2 shows the manufacturing method of each example. Casting was carried out in two ways: DC casting with a thickness of 500 mm and CC with a thickness of 7 mm. The intermediate annealing was performed by CAL at a heating rate / cooling rate of about 20 ° C / s, and in a batch furnace (abbreviated as BAF) without heating, the heating rate / cooling rate was about 35 ° C / h. The holding time was 2 hours. The final heat treatment is carried out in a batch type annealing furnace for 160 ° C. or 190 ° C. × 2 hr, and in a furnace equivalent to a batch type coating baking furnace for 200 ° C. × 20 min.
For 20 s, a continuous type paint baking furnace was used. Explaining each sample number shown in Table 2, No. 1 applies the manufacturing method (4) described above to the alloy A satisfying Fe + Mn <0.7%. No. 2 to 5 are alloys B satisfying 0.5% <Fe + Mn <1.2%, while No2 is the manufacturing method (2) described above.
No. 3 applies the manufacturing method (3), No 4 applies the manufacturing method (5), and No 5 applies the manufacturing method (6).・ No6 has a proof stress of the original plate of 250 N / mm with respect to No5.
^The manufacturing conditions are set so as to be less than ² . -No7 and No8 apply the manufacturing method (7) mentioned above to C alloy with which 1 <Fe + Mn <= 1.6%. In No. 7, the final heat treatment was performed in batch, and in No. 8, the final heat treatment was performed by CAL. -No. 9 is manufactured by the conventional method using the conventional alloy D. -No. 10 is manufactured by using the manufacturing method (5) described above for the alloy E having a component composition outside the scope of the present invention.

[0015]

[Table 2]

The strength, moldability and structure of each sample were evaluated. The results are shown in Table 3. Here, "after 15% rolling" means a rolling ratio of 15 which corresponds to forming into a tab.
% Cold-rolled, and “after heating at 150 ° C. × 1 h” means that the tab was formed and accelerated heating corresponding to the state after one year had passed at room temperature was applied. TS represents tensile strength, YS represents 0.2% proof stress, and the unit is N / mm ² . Also, El represents elongation and the unit is%. The yield strength difference is "15% after rolling" and "15% after rolling".
The difference in proof stress after heating at 0 ° C. × 1 h ”, that is, the amount of softening with time corresponding to the amount of softening with time in one year is shown. The bendability was evaluated by a repeated bending test and a bending test.
In the repeated bending test, as shown in FIG. 1, the number of times until the test piece is grasped and bent at an angle of 90 ° on both sides is defined as one and the fracture is shown. In the bending test, the shape shown in FIG. 2 was bent at a bending radius of 1/2 × (plate thickness), the bending surface 2 was observed, and the conventional material was compared with ◯. In the figure, RD indicates the rolling direction of the test piece. The structure is observed by observing the plate surface as crystallized substances and determining the number of particles of 1 μm or more
It is shown in units of 0.2 mm ² . Also, the plate surface was observed as crystallized substances, and the number of coarse particles of 5 μm or more was counted as 0/0.
It is shown in units of 2 mm ² . In addition, the evaluation of the can openability is equivalent to one year after the tab is formed and attached to the can lid.
The case where the can was opened after being subjected to the accelerated heat treatment at 0 ° C. × 1 h was indicated as ◯, and the case where the tab could not be opened due to insufficient strength at the time of opening the can was indicated as x.

[0017]

[Table 3]

As shown in Table 3 above, under any of the conditions, the invention example has strength or bendability equal to or better than that of the conventional material as compared with the conventional material and the comparative material, and the decrease of proof stress, that is, softening with time, of the conventional material. The yield strength after accelerated heating, which is less after one year, is higher in the invention example than in the conventional example. Hereinafter, each will be described. [No1] The alloy A that satisfies Fe + Mn <0.7% is obtained by applying the manufacturing method (4) described above. Tensile strength,
The yield strength is the same as that of the conventional example No. 9 even after the base plate and 15% rolling, and the yield strength is less decreased even after the accelerated heating.
It shows a strength higher than 9. Also, the amount of coarse crystallized substances is small,
The bendability and the repetitive bendability are the same values as those of Conventional Example No. 9, and there is no problem in the can openability. [No2] An alloy B satisfying 0.5% <Fe + Mn <1.2% is manufactured by the manufacturing method (2) described above. Although the strength is slightly lower than that of Conventional Example No. 9, the strength is almost the same, and the yield strength is not significantly reduced. Further, the repetitive bendability is equivalent to that of the conventional example No. 9 because both the fine crystallized substance and the coarse crystallized substance are crystallized similarly to the conventional example No. 9, but are slightly inferior to the invention example No. 1. [No3] The alloy B satisfying 0.5% <Fe + Mn <1.2% is manufactured by the above-mentioned manufacturing method (3). It has the same performance as No. 2, but the strength is lower than that of No. 2 because the intermediate annealing is performed in batch. [No4] It is manufactured by the manufacturing method (5) described above using the alloy B satisfying 0.5% <Fe + Mn <1.2%. The strength is the same as that of the conventional example for both the base plate and after 15% rolling.
It has the same strength as 9 and has less softening over time.
Even in the state equivalent to the passage of the year, the proof stress of the conventional example No. 9 is 294.
Inventive Example No. 4 is 3 while it has fallen to N / mm ^2.
It is 45 N / mm ² , and maintains sufficient strength. Further, although the number of fine crystallized substances is increased, the bendability and the repetitive bendability are the same as those of Conventional Example No. 9. [No5] It is manufactured by the manufacturing method (6) described above using the alloy B satisfying 0.5% <Fe + Mn <1.2%. Since the intermediate annealing was performed in a batch, the strength was slightly reduced as compared with No. 4, but the repetitive bendability was improved. [No6] The yield strength of the base plate is 250 N / mm with respect to No5.
^This is a comparative example with less than ² . Although there is little softening over time,
The yield strength after one year is 245 N / mm ² , which is low compared to other materials, and therefore the can openability is poor. [No7] It is manufactured by the above-described manufacturing method (7) using the alloy C satisfying 1 <Fe + Mn ≦ 1.6%. Although the composition has a smaller amount of Mg than the alloys of No. 1 to No. 6, the strength is almost the same as that of the conventional example No. 9 by increasing the amount of Mn. The difference in yield strength is also small. Although the amount of crystallized substances was larger than that of the other invention examples, the bendability and the repetitive bendability were equivalent. [No8] The final heat treatment is performed on No7 by CAL. Although the strength after 15% rolling is slightly lower than that of No. 7, the difference in proof stress is 20 N / mm ^{2, which} is the smallest amount of softening with time and the decrease in tensile strength. In addition, the moldability and can openability are equivalent to those of No7. [No9] A conventional alloy D was manufactured by a conventional method. After the original plate and 15% rolling, that is, after forming the tab, it shows high strength at the equivalent time, but 150 ° C which is equivalent to one year
After accelerated heating for x1 h, the proof stress decreased by 76 N / mm ² , showing a large softening with time. The tensile strength is also reduced by 29 N / mm ² . Further, since the number of coarse crystallized substances is large, the cyclic bendability is not so good. [No10] This is a comparative example using alloy E having a component composition outside the scope of the claims of the present invention. Since the amount of Mn + Fe is large, the strength is the same as that of the conventional example even if the amount of Mg is small. However, since many fine crystallized substances are crystallized out, both bendability and repetitive bendability are extremely poor. As described above, the aluminum alloy sheet according to the present invention has a tensile strength and a proof stress immediately after forming the base sheet and the tabs, which are equal to or slightly lower than those of the conventional material, and are less likely to soften with time. Further, the moldability such as bendability and repetitive bendability is equal to or higher than that of the conventional material.

[0019]

[Effect] As described in detail above, according to the present invention, the strength and bending workability required for a steion tab material for beer cans, carbonated beverage cans, etc. are satisfied, and there is little softening with time after tab formation. That is, it is possible to provide an excellent aluminum alloy plate for a Steion tab. That is, the strength after forming the base plate and the tab shows sufficient strength equivalent to that of the conventional material, and since the decrease in strength due to the softening with time is small, the tab material can be formed even after the tab material has been formed or a long time has passed after the product is manufactured. The required strength can be maintained.
Therefore, when opening the can, there is no problem that the tab bends due to insufficient strength and cannot be opened. Furthermore, since sufficient strength can be maintained for a long period of time, it is possible to sufficiently cope with the thinning of high strength required for tab materials in recent years. In addition, as described in detail, the production of the aluminum alloy sheet according to the present invention does not require special equipment and strict production conditions, and each step itself is superior by performing a combination of the most practicable methods. An aluminum alloy plate for a Steion tab can be obtained. Therefore, it is excellent in terms of manufacturing cost and the like. Further, by appropriately selecting the manufacturing method according to the alloy component composition, the original plate strength,
It is possible to obtain an aluminum alloy plate exhibiting particularly excellent performance in either formability or softening amount over time. Therefore, the cost can be further reduced by selecting the manufacturing conditions by paying attention to the performance that is highly required. As described above, the aluminum alloy plate for a steion tab according to the present invention is excellent in stability of performance such as strength and moldability, and in manufacturing in terms of cost and the like.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a repeated bending test in an example of the present invention.

FIG. 2 is a perspective view showing a bending test in an example of the present invention.

[Explanation of symbols]

 1 Bending line 2 Bending observation surface RD Rolling direction

Claims (1)

[Claims] 1. Mg: 1-3 by weight (hereinafter the same)
%, And Ti: 0.005 for refinement and stabilization of the structure
.About.0.20% alone or B: 0.0005 to 0.
It is contained together with 04%, and further Fe: 0.01 to 0.6
%, Mn: 0.1 to 1.2%, Si: 0.05 to 0.5
%, Cu: 0.05 to 0.5%, Cr: 0.05 to 0.
3%, Zn: One or more of 0.1 to 0.5% is included, and Fe and Mn must include at least one of them and Fe + Mn ≦ 1.6% or less, and the balance Consists of Al and inevitable impurities, and has a proof stress of 25
Aluminum alloy plate for Steion tab that is hard to soften with time at 0 N / mm ² or more.