JP4943714B2 - High strength aluminum alloy plate for wide-mouth bottle can cap - Google Patents

Description

  The present invention relates to an Al—Mg—Mn—Si—Fe (aluminum-magnesium-manganese-silicon-iron) -based alloy plate suitably used for a PP (pilfer proof) cap for a wide-mouth bottle can.

  PP caps are generally coated and printed on a material aluminum alloy plate, then formed into a plurality of cylindrical cups at the same time, trimmed at the ears of each cup, and then processed into perforations at the hem. It is manufactured by the process. The cap formed in this way is filled with the contents in the beverage container, wound around the threaded portion of the container, and put on the market.

Until now, Al-Mn 3105 alloy (see Patent Document 1) or Al-Fe 8011 alloy has been mainly used for PP caps with a diameter of 28 mm or less (see Non-Patent Document 1). . On the other hand, Al-Mg-based 5151 alloy (Al-1.5 to 2.1% Mg alloy) is used for a wide-mouth cap having a diameter of 38 mm or the like because it needs to have higher strength.
However, when high internal pressure is applied by the contents, for example, when the contents are carbonic acid, the contents are leaked due to deformation of the cap, blow-off (cap blows off at once), and the drop impact at the vending machine There is a risk of deformation. Therefore, a plate having higher strength and better openability is expected.

  As an alloy that can meet the expectation of such high strength and good openability, there is an Al-Mg-Mn alloy. In the prior art (refer to Patent Document 2) in which the final cold rolling rate and the crystal grain size of the Al—Mg—Mn alloy plate are limited, there is an example of 263 MPa as a tensile strength of 200 MPa or more. Is 2%, and PP caps for wide-mouth bottle cans may cause problems such as cracking during molding.

Moreover, in the prior art (refer patent document 3) which limited the conditions from the homogenization process of Al-Mg-Mn type alloy to finish annealing (refer patent document 3), the tensile strength is 141 MPa in an example at the maximum, and 152 MPa in a comparative example, The strength is too low to apply to PP caps for wide-bottle cans.
Furthermore, even in the prior art (see Patent Document 4) in which the final annealing conditions by rapid heating and cooling are limited (see Patent Document 4), the maximum tensile strength is 185 MPa, and the strength is too low.

  On the other hand, as an example of an Al-Mg-Mn alloy having high tensile strength, there is a prior art (see Patent Document 5) showing an example exceeding 200 MPa, but it is not for a PP cap by deep drawing but by a ring pull. It is for shallow-drawn wide-mouthed caps that are opened by tearing, and emphasizes the tearability of the score processing part, and is used differently from the present invention.

  Further, when the strength is increased by a method such as an increase in the degree of cold rolling and a decrease in the final heat treatment temperature and time, there is a problem that the elongation is insufficient. In such a case, problems such as a decrease in moldability such as cracking at the time of molding, difficulty in forming unevenness (screw shape) of the cap body portion, and a perforation portion being difficult to break at the time of opening the plug occur.

Japanese Patent No. 3153541 JP 58-224142 A Japanese Patent Laid-Open No. 9-25546 JP 2000-282195 A JP 2000-282164 A Sumitomo Light Metal Technical Report, vol. 23 (1982), p. 36.

  The present invention has been made in view of such conventional problems, and has a wide mouth bottle can cap which is excellent in moldability, strength and openability by limiting the material design (optimization of components, strength and elongation) and the material structure. An object of the present invention is to provide a high-strength aluminum alloy sheet for use.

The present invention, after painting / printing, is formed into a cylindrical cup having a diameter of more than 28 mm, trims the ear of the cup, then processes the perforation at the hem, and then the beverage container filled with the contents It is a high-strength aluminum alloy plate for a wide-mouth bottle can cap that is wound around the screw part of
Mg: 1.0 to 2.0 % (% by weight, the same applies hereinafter)
Mn: 0.2 to 1.0%
Si: 0.01 to 0.5%,
Fe: 0.01 to 0.69% included, the balance is made of inevitable impurities and aluminum,
The total amount of Mg and Mn is 1.5 to 2.5%,
The total amount of Si and Fe is 0.2-0.7%,
The base plate of the aluminum alloy plate has a tensile strength of 200 to 270 MPa, a proof stress of 170 to 240 MPa, and an elongation of 3 to 8%.
With respect to the base plate, the tensile strength of the blank plate subjected to heat treatment held at a temperature of 200 ° C. for 10 minutes is 200 to 270 MPa, the proof stress is 160 to 230 MPa, and the elongation is 5 to 10%.
The distribution density of the intermetallic compound having a size of 0.5 μm or more is 3000 to 10,000 pieces / mm ² , and the area ratio of the intermetallic compound is 0.5 to 3.0%,
A high-strength aluminum alloy plate for a wide-mouth bottle can cap, characterized in that the distribution density of intermetallic compounds having a size of 3 μm or more is 300 to 1500 / mm ² (Claim 1).

First, the reason for limiting the chemical composition in the present invention will be described.
Mg is an essential component of the present invention, and by limiting its content to 1.0 to 2.5%, strength and formability can be kept good.
When the Mg content is less than 1.0%, the strength is insufficient to cope with high internal pressure contents or gauge down, so that a predetermined pressure resistance is obtained as a wide-mouth bottle can cap (hereinafter simply referred to as a cap). I can't. In addition, there is a problem that the rigidity of the threaded portion in the molded cap and the effect of preventing doming on the top surface cannot be sufficiently obtained. In addition, four ears in the 0 °, 90 °, 180 °, and 270 ° directions with respect to the rolling direction are easily developed, so it is difficult to stably obtain a material with a low ear rate, and it is difficult to bend characters. It is not easy to mass-produce. Character bending referred to here is a phenomenon in which printed pictures and characters are bent and displayed depending on how the material is deformed due to the characteristics of the method of manufacturing a cap that is molded into a cup shape after printing in a flat state. That means.
The larger the Mg content, the finer the crystal grains. By increasing the Mg content and increasing the crystal grain refining effect, it becomes easy to suppress rough skin during cup molding.

  On the other hand, when the Mg content exceeds 2.5%, the strength is too high, and a great amount of force is required at the time of opening, so that it is difficult to open the plug. Therefore, the Mg content is preferably 2.5% or less. The Mg content is preferably more than 1.3%, less than 2.2%, more preferably more than 1.5%, in order to satisfy the above-described anisotropy and strength in a balanced manner and facilitate production. Less than 2.0% is good.

  Mn is an essential component of the present invention in order to maintain good strength and moldability. In addition, an intermetallic compound is formed together with an element such as Fe, which can be a starting point and a propagation path of a crack when a perforation breaks due to cap opening. The Mn content is limited to 0.01 to 1.0%. When the Mn content is less than 0.01%, it is difficult to obtain a predetermined performance as a cap due to insufficient strength, and it is necessary to use a high purity metal. On the other hand, if it exceeds 1.0%, the strength is so high that a large amount of force is required at the time of opening and it is difficult to open, or a huge intermetallic compound is easily formed together with elements such as Fe at the time of casting.

  The Mn content is preferably 0.01 to 0.8%. The reason for suppressing the upper limit of the amount of Mn is that the higher the Mg content, the higher the strength while maintaining the formability, but the ingot cannot be homogenized at high temperature, and the Mn-based precipitates that affect the ear rate are affected. This is because it becomes difficult to control.

  Si forms a compound with Mn and Fe and forms a crystallized product, and is an essential component in the present invention. Si content is limited to 0.01 to 0.5%. If the Si content is less than 0.01%, it is necessary to use a high purity metal, which increases costs. Moreover, when Si content exceeds 0.5%, the said crystallized substance will increase and cap moldability will deteriorate.

  Fe is an essential component in the present invention in order to affect the formability by crystal grain refinement. Fe content is limited to 0.01 to 0.69%. When the Fe content is less than 0.01%, not only the effect is not obtained, but also it is necessary to use a high-purity bullion, resulting in an increase in cost. Further, when the Fe content exceeds 0.69%, the crystal grain refining effect is saturated and exceeds the appropriate range of Si + Fe amount described later.

Furthermore, the reasons for limiting the total value of Mg and Mn and the total value of Si and Fe will be described.
The total value of Mg and Mn (Mg + Mn) is limited to 1.5 to 2.5%. When Mg + Mn is less than 1.5%, high strength cannot be obtained. Further, when Mg + Mn exceeds 2.5%, the strength is too high, and a great amount of force is required at the time of opening, so that there is a problem that it is difficult to open.

  The total value of Si and Fe (Si + Fe) is limited to 0.2 to 0.7%. When Si + Fe is less than 0.2%, the amount of intermetallic compound necessary for opening the plug cannot be secured. On the other hand, when Si + Fe exceeds 0.7%, the amount of intermetallic compound becomes excessive, leading to a decrease in elongation, and easily cracking during molding.

  Next, the base plate refers to the aluminum alloy plate of the present invention itself, that is, the plate in the state as manufactured and before being supplied to the cap manufacturing process. The blank plate is a plate in which the base plate is subjected to the heat treatment as described above, and the state after printing in the cap manufacturing process is reflected to some extent for convenience.

The strength of the base plate is limited to a range where the tensile strength is 200 to 270 MPa, the proof stress is 170 to 240 MPa, and the elongation is 3 to 8%. And the intensity | strength of the said baked board is limited to the range whose tensile strength is 200-270 MPa, yield strength is 160-230 MPa, and elongation is 5-10%.
If the tensile strength and proof stress of the base plate are not within the above ranges, it will be difficult to obtain the desired strength after baking.

If the tensile strength of the Sorasho plate may, and yield strength of less than 200MPa than 1 6 0 MPa can not obtain a predetermined breakdown voltage in molded cap. On the other hand, when the tensile strength of the blank plate exceeds 270 MPa and when the proof stress exceeds 230 MPa, there is a problem that it is difficult to open the molded cap. If the elongation of the blank plate is less than 5%, molding defects such as cracks are likely to occur during cap molding, and if it exceeds 10%,
There is a problem that the perforation is difficult to cut when opening, the opening angle is increased, and opening is difficult.

Next, in the present invention, the distribution density of the intermetallic compound having a size of 0.5 μm or more is limited to 3000 to 10,000 pieces / mm ² , the area ratio is limited to 0.5% or more and 3.0% or less, The distribution density of intermetallic compounds having a size of 3 μm or more is limited to 300-1500 pieces / mm ² .
When the distribution density of the intermetallic compound having the specific size is below the lower limit of the above range, the metal compound is less likely to become a crack starting point or propagation path when the cap is opened. Moreover, when exceeding an upper limit, elongation is small and there exists a possibility that it may become easy to break at the time of shaping | molding.

In the present invention, the Mn content is 0.2% or more . Thereby , the effect that it is easy to obtain predetermined intensity | strength and an intermetallic compound is acquired. In addition, the can body material 3004 alloy and 3104 alloy can be recycled for easy use.

Moreover, the said aluminum alloy plate is further Cu: 0.01-0.25%, Cr: 0.01-0.25%, Zn: 0.01-0.25%, Ti: 0.005-0. It is preferable to contain one or more of 05% ( claim 2 ).

Cu: 0.01 to 0.25%;
Cu is an element that affects the material strength. If it is less than 0.01%, not only the effect cannot be obtained, but it is necessary to use a high purity metal, resulting in an increase in cost. Addition exceeding 0.25% makes rolling difficult.

Cr: 0.01-0.25%, Zn: 0.01-0.25%;
Cr and Zn are elements that affect the formability by crystal grain refinement. If each of these is less than the above lower limit, not only the effect cannot be obtained, but it is necessary to use a high purity metal, resulting in an increase in cost. On the other hand, when the above upper limit is exceeded, the crystal grain refining effect is saturated. Therefore, the upper limit is preferably taken into consideration in view of the cost increase required for addition.

Ti: 0.005 to 0.05%;
Ti is an element that affects the improvement of formability by refining the ingot structure. If it is less than 0.005%, the effect cannot be obtained. If it exceeds 0.05%, an insoluble Al—Ti compound tends to appear as a surface defect in the final product.
In addition, when adding an Al-Ti-B intermediate alloy as an ingot structure | tissue refiner, B contains, but it is preferable to add B in 0.02% or less of range.

Next, among the ears generated at the opening of the drawing cup used for the ear ratio test of the base plate or the blank plate, four locations in the 45 ° direction with respect to the rolling direction, or 0 °, 90 °, 180 ° Ears of ears occurring at four locations in the 270 ° direction are 2.5% or less, and ears of ears occurring at two locations of 0 ° and 180 ° with respect to the rolling direction are 2.0% or less. ( Claim 3 ).

  When the ear rate of the four ears in the 45 ° direction exceeds 2.5%, bending of printed characters or the like at the skirt portion of the molded cap becomes noticeable in the 45 ° direction and is difficult to prevent. The smaller the ear ratio, that is, the lower limit is preferably 0%, but it is difficult due to the nature of the metal plate. Actually, an ear rate of 0.5% to 2.0% is more preferable.

  Further, even when the ear rate of the ears generated at the four locations in the 0 °, 90 °, 180 °, and 270 ° directions exceeds 2.5%, the ear rate at the four locations in the 45 ° direction is 2.5%. As in the case of exceeding, bending of printed characters or the like becomes remarkable.

  Furthermore, even when the ear-ear ratio occurring at two locations in the 0 ° and 180 ° directions with respect to the rolling direction exceeds 2.0%, it is possible to prevent bending of printed characters and the like on the molded cap hem portion. It becomes difficult. In the case of drawing of an Al-low Mg alloy, ears in the directions of 0 ° and 180 ° are particularly likely to occur with respect to the rolling direction, and it is important to control the ears in this direction. And in order to suppress the bending of printed characters and the like more reliably, it is preferable to set the ear ratio of the ears generated at 0 ° and 180 ° with respect to the rolling direction to 1.5% or less.

  The generation state and strength characteristics of the ear rate can be adjusted not only by the contents of Mg, Mn, Si, and Fe but also by other manufacturing conditions.

  Here, the drawn cup is a cup-shaped test material obtained by drawing a blank cut out from the cap Al—Mg alloy plate under predetermined conditions. At the opening end of the throttle cup, the portion protruding in the axial direction is called an ear, and the most depressed portion between the ears is called a valley. The distance from the bottom of the squeeze cup to the tip of the ear is defined as the ear height, and the distance from the bottom of the squeeze cup to the tip of the valley is defined as the valley height. The ear rate can be calculated as follows.

<Ear rate of ears at 45 points in 45 ° direction>
45 ° ear height = A, 135 ° ear height = B, 225 ° ear height = C, 315 ° ear height = D,
Minimum valley height between 45 ° and 135 ° = E,
Minimum valley height between 135 ° and 225 ° = F,
Minimum valley height between 225 ° and 315 ° = G,
Minimum valley height between 315 ° and 45 ° = H,
Ear average: M45 = (A + B + C + D) / 4,
Average valley: V45 = (E + F + G + H) / 4
Ear rate = [(M45−V45) / {(M45 + V45) / 2}] × 100 (%)

<Ear rate of ears at 4 locations in 0 °, 90 °, 180 °, 270 ° direction>
0 ° ear height = A ′, 90 ° ear height = B ′, 180 ° ear height = C ′, 270 ° ear height = D ′, minimum valley height between 0 ° and 90 ° = E ',
Minimum valley height between 90 ° and 180 ° = F ′,
Minimum valley height between 180 ° and 270 ° = G ′,
Minimum valley height between 270 ° and 0 ° = H ′,
Ear average: M ′ = (A ′ + B ′ + C ′ + D ′) / 4
Average valley: V ′ = (E ′ + F ′ + G ′ + H ′) / 4
Ear rate = [(M′−V ′) / {(M ′ + V ′) / 2}] × 100 (%)

<Ear ratio of ears at two locations at 0 ° and 180 °>
Average height of cup = P (average height obtained by measuring the height of the open end at 1000 points),
0 ° ear height = Q, 180 ° ear height = R,
Ear average: S = (Q + R) / 2,
Ear rate = {(SP) / P} × 100 (%)

<Cup drawing molding conditions>
Using a die with a die diameter of 33.6 mm, a punch diameter of 33 mm, and a punch shoulder R of 1.5 mm, a cup blank was carried out with a drawing material blank diameter of 55 mm and a drawing ratio of 1.67.

Further, the aluminum alloy plate is preferably crystal particle diameter of 50μm or less (claim 4).
In this case, an effect that rough skin hardly occurs at the time of cap molding can be obtained.

Further, the aluminum alloy plate is preferably 90 ° cyclic bending number 14-18 times (claim 5).
As shown in the examples described later, the 90 ° repeated bending is performed by bending 90 ° in one direction (counting this once) under the condition of bending R = 1.0 mm from a predetermined position from the horizontal state. Next, after returning to the horizontal state (this is also counted as one time), bending 90 ° in the opposite direction (this is also counted as one time) was repeated, and the number of times of bending until cracking was evaluated, and the cap was opened. This is a test used as an index of the shearing force.
When the number of times of bending is less than 14, the perforated portion is likely to be sheared and broken, and the internal pressure by the content may result in a cap that has a risk of content leakage or blow-off.
Further, when the number of times of bending exceeds 18, the perforated portion is difficult to shear and may become a cap that is difficult to open.

Next, preferable production conditions for obtaining the aluminum alloy plate of the present invention will be described.
The basic manufacturing process is to homogenize and heat the ingot, then hot-roll to form a plate, and then anneal, cold-roll, anneal, and cold-roll sequentially to obtain the product thickness, and finally strength In order to stabilize the heat treatment, stabilization heat treatment is performed. In many cases, surface treatment such as degreasing and chemical conversion treatment is performed before or after the stabilization heat treatment.

  The said homogenization heat processing is the conditions which hold | maintain an ingot at the temperature of 450-550 degreeC for 1 to 24 hours. If the holding temperature is less than 450 ° C. or the holding time is less than 1 hour, the ear formation becomes unstable and control becomes difficult. When the holding temperature exceeds 550 ° C. or the holding time exceeds 24 hours, Mg easily diffuses on the surface, the Mg oxide layer on the surface becomes thick, and the amount of chamfering needs to be excessively increased, which is uneconomical.

Subsequently, for example, hot rolling, annealing, cold rolling, annealing, cold rolling, and stabilizing heat treatment are sequentially performed. In this step, a predetermined strength and ear rate can be obtained.
In the said annealing 1 and 2, it carries out on the conditions hold | maintained at the temperature of 300-550 degreeC. When the holding temperature is less than 300 ° C., a predetermined ear ratio cannot be obtained with the final plate, and the strength becomes too high and the moldability is poor. When the holding temperature exceeds 550 ° C., the surface tends to be oxidized, which is not preferable. The holding time is not particularly limited, but when annealing at a relatively high temperature such as rapid heating / cooling using a continuous annealing line or the like, holding is performed for 0 to 20 seconds, holding when annealing at a relatively low temperature using a batch annealing furnace. 30 minutes to 5 hours is appropriate.

  What is necessary is just to perform the cold rolling 2 after the said annealing 2 in 30 to 70% of range. When the rolling rate is less than 30%, it is difficult to obtain a predetermined strength, and it becomes difficult to obtain a predetermined ear rate. If the rolling rate exceeds 70%, the formability is lowered, the strength is too high and it is difficult to open the plug, and the rolling texture is developed so much that the ears in the 45 ° direction become large.

  The performance as a cap material is almost achieved with cold rolling, but in the case of an Al-Mg alloy, when the cold rolling is left at room temperature, a phenomenon in which the strength gradually decreases occurs. In order to prevent this and stabilize the strength, a heat treatment (stabilized heat treatment) for heating at a temperature of 100 to 300 ° C. for 30 minutes or more is necessary. If it is less than 100 ° C., the strength is not stable, and if it exceeds the upper limit of 300 ° C., softening increases and a predetermined strength cannot be obtained.

The contents of this example will be described with reference to specific examples, but the following shows one example of the present invention, and the present invention is not limited to this.
(Examples and Reference Examples )
A 500 mm thick, 800 mm wide, 2000 mm long aluminum alloy ingot containing the chemical components shown in Table 1 is formed by DC casting, and the segregation layer on the surface is cut by 15 mm and then kept at 500 ° C. for 12 hours. The hot rolling was started at 450 ° C. immediately after the heat treatment. Hot rolling was performed to a plate thickness of 3 mm, and the process was terminated at 250 ° C. Then, after obtaining a recrystallized structure by annealing at 380 ° C. for 1 hour using a batch annealing furnace, it was cold-rolled to a thickness of 0.5 mm, and further a continuous annealing line at 500 ° C. for 3 seconds. After using the intermediate annealing to obtain a recrystallized structure, it was cold-rolled at a rolling rate of 40% to a plate thickness of 0.3 mm, and subjected to a stabilization heat treatment at 200 ° C. for 2 hours to obtain a test material.
The following evaluation tests were performed using the obtained six types of test materials E1 to E6. Some specimens were observed for material structure.

<Strength>
A tensile test was performed on a JIS No. 5 test piece, and the tensile strength, proof stress, and elongation were measured.
<Ear rate>
Using a die with a die diameter of 33.6 mm, a punch diameter of 33 mm, and a punch shoulder R of 1.5 mm, a cup blank was carried out with a drawing material blank diameter of 55 mm and a drawing ratio of 1.67.
The ear rate is calculated based on the above-mentioned conditions, and the ear rate of the ears at 45 locations in the 45 ° direction (A direction), 4 locations at the 0 °, 90 °, 180 °, and 270 ° directions (in the B direction) ) And two ears at 0 ° and 180 ° directions were measured.
<Crystal grain size>
The plate surface of the test material was electropolished and the crystal grains were observed with a polarizing microscope. The crystal grain size was determined from the comparative method using an ASTM card.
<Repeated bending>
In the repeated bending test, first, as shown in FIG. 1, a specimen 1 having a length of 200 mm and a width of 12.5 mm with the rolling direction as a longitudinal direction is held by a chuck 5, and a load is applied without the specimen 1 being bent. Do so. Then, the test material 1 is subjected to a bending of R = 1.0 mm by rotating the chuck 5 as shown in the figure with a stress of about 15% of the proof stress being applied.
That is, the repeated bending test repeats 90 ° bending from the base point to one side (a), then returning to the base point (b), 90 ° bending in the opposite direction (c), and returning to the base point again (d). This is a swing test.
The number of times of bending was counted as one time every 90 degrees, and the number of times of repeated bending until cracking was evaluated.

In the repeated bending test, the bending is stopped when a crack occurs and the load changes. The number of repeated bending is calculated as follows.
The number of times of 90 ° bending is defined as X, and Y is obtained by dividing the angle moved until the repeated bending tester stops by 90 ° after performing bending repeatedly X times. Then, the number of repeated bends = X + Y, and numbers up to one decimal place are adopted. Moreover, in each test material, an average value obtained by repeating the repeated test up to cracking five times is taken as a measurement result.

Table 2 shows the evaluation results. In addition, A and B in the ear rate in the same table indicate that A: 4 points in the 45 ° direction and B: 4 points in the ears at the 0 °, 90 °, 180 °, and 270 ° directions. The same applies to Table 4.)
The test materials E1 to E6 of this example all showed good results as cap materials for wide-mouth bottle can caps in all evaluation items of tensile strength, yield strength, elongation, ear rate, and crystal grain size.

(Comparative example )
Aluminum alloy ingots having components that are outside the scope of the present invention shown in Table 3 were produced under the same conditions as in the above Examples and Reference Examples, and specimens C1 to C6 were obtained.

These evaluation results are shown in Table 4.
As can be seen from Table 4, since the content of Mg and Mg + Mn exceeds the upper limit of the present invention, the sample C1 has high tensile strength and proof stress and is too strong. Moreover, since the balance of anisotropy is deteriorated and the ear ratio of the ears at the four positions in the 45 ° direction exceeds the upper limit of the preferable range of the present invention, it is difficult to prevent the character from being bent. In addition, since the number of repeated bending is less than the lower limit of the preferred range of the present invention, the perforation portion is likely to be sheared and broken, so that it is possible to become a cap having the risk of content leakage and blow-off due to internal pressure due to the content There is sex.

  Moreover, since the content of Mg and Mg + Mn is less than the lower limit of the present invention in the sample C2, the tensile strength and the yield strength cannot be obtained, the strength is insufficient, and the predetermined withstand pressure cannot be obtained. Moreover, since the crystal grain structure exceeds the upper limit of the preferred range of the present invention, rough skin tends to occur during cap molding.

  In sample C3, the content of Mg + Mn exceeds the upper limit of the present invention, so the tensile strength and proof stress are large, the strength is too high, and the balance of anisotropy is deteriorated, resulting in four locations in the 45 ° direction. Since the ear rate of the ear exceeds the upper limit of the preferred range of the present invention, it is difficult to prevent the bending of characters. In addition, since the number of repeated bending is less than the lower limit of the preferred range of the present invention, the perforation portion is likely to be sheared and broken, so that it is possible to become a cap having the risk of content leakage and blow-off due to internal pressure due to the content. There is sex.

In Sample C4, the Mg + Mn content is below the lower limit of the present invention, so that the tensile strength and the yield strength cannot be obtained, the strength is insufficient, and the predetermined withstand pressure cannot be obtained. Moreover, since the number of times of repeated bending exceeds the upper limit of the preferred range of the present invention, the perforation portion is difficult to shear and break, so that it may be difficult to open the cap.
Moreover, since the ear ratios of the ears at two locations in the directions of 0 ° and 180 ° exceed the upper limit of the preferable range of the present invention, it is difficult to prevent character bending.

  In Sample C5, the content of Si + Fe exceeds the upper limit of the present invention, and the distribution density and area ratio of the intermetallic compound that is 0.5 μm or more exceed the upper limit of the present invention, and the size is 3 μm or more. Since the distribution density of a certain intermetallic compound exceeds the upper limit of the present invention, the amount of the intermetallic compound becomes excessive, resulting in a decrease in elongation and easy cracking during molding.

  Moreover, since the content of Si + Fe is less than the lower limit of the present invention in sample C6, the amount of intermetallic compound necessary for opening the plug cannot be ensured. That is, as shown in Table 2, the distribution density and area ratio of intermetallic compounds having a size of 0.5 μm or more, and the distribution density of intermetallic compounds having a size of 3 μm or more are below the lower limit of the present invention. Therefore, since there are few intermetallic compounds which become the starting point of a crack at the time of cap opening and a propagation path, it may become a cap which is hard to open.

Explanatory drawing which shows a repeated bending test machine.

Explanation of symbols

1 Test material 5 Chuck

Claims (5)

After painting and printing, the cup is molded into a cylindrical cup with a diameter of more than 28 mm, the ear of the cup is trimmed, the perforation is processed in the hem, and then the beverage container filled with the contents is threaded. A high-strength aluminum alloy plate for a wide-mouth bottle can cap to be wound ,
Mg: 1.0 to 2.0 % (% by weight, the same applies hereinafter)
Mn: 0.2 to 1.0%
Si: 0.01 to 0.5%,
Fe: 0.01 to 0.69% included, the balance is made of inevitable impurities and aluminum,
The total amount of Mg and Mn is 1.5 to 2.5%,
The total amount of Si and Fe is 0.2-0.7%,
The base plate of the aluminum alloy plate has a tensile strength of 200 to 270 MPa, a proof stress of 170 to 240 MPa, and an elongation of 3 to 8%.
With respect to the base plate, the tensile strength of the blank plate subjected to heat treatment held at a temperature of 200 ° C. for 10 minutes is 200 to 270 MPa, the proof stress is 160 to 230 MPa, and the elongation is 5 to 10%.
The distribution density of the intermetallic compound having a size of 0.5 μm or more is 3000 to 10,000 pieces / mm ² , and the area ratio of the intermetallic compound is 0.5 to 3.0%,
A high-strength aluminum alloy plate for wide-mouth bottle can caps, wherein the distribution density of intermetallic compounds having a size of 3 μm or more is 300 to 1500 / mm ² .   In Claim 1, the said aluminum alloy plate is further Cu: 0.01-0.25%, Cr: 0.01-0.25%, Zn: 0.01-0.25%, Ti: 0.005 A high-strength aluminum alloy plate for wide-mouth bottle can caps, comprising one or more of 0.05%.   In Claim 1 or 2, among the ear | edge which generate | occur | produces in the opening part of the draw cup used for the ear | edge rate test of the said base plate or the said baked plate, four places of 45 degrees direction with respect to a rolling direction, or 0 degree, 90 The ear rate of ears occurring at four locations in the directions of °, 180 °, and 270 ° is 2.5% or less, and the ear rate of ears occurring at two locations in the directions of 0 ° and 180 ° with respect to the rolling direction is 2. A high-strength aluminum alloy plate for a wide-mouth bottle can cap, characterized by being 0.0% or less.   The high-strength aluminum alloy plate for a wide-mouth bottle can cap according to any one of claims 1 to 3, wherein the crystal grain size of the aluminum alloy plate is 50 µm or less.   The high-strength aluminum alloy plate for a wide-mouth bottle can cap according to any one of claims 1 to 4, wherein the aluminum alloy plate has a 90 ° repetitive bending frequency of 14 to 18 times.

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