JP6667189B2 - Aluminum alloy plate for tab and manufacturing method thereof - Google Patents

Description

  The present invention relates to a tab aluminum alloy plate suitable as a material for a tab attached to a can lid and a method for producing the same.

  Steel cans and aluminum cans are widely used as packaging containers for beverages and foods. These cans have a can body and a can lid for sealing the contents, and a tab for opening the can lid. For example, the can lid of a beverage can often has either a pull-tab system in which the score portion of the can lid is removed together with the tab, or a stay-tab system in which the score portion of the can lid is pushed by the tab. . In recent years, a stay-tab type can lid has become mainstream from the viewpoint of environmental problems and the like.

  The tab is attached to a rivet formed in the can lid. For example, when opening a can lid of the stay-ion tub type, the tab is caused to push the score portion of the can lid into the can by the principle of leverage. However, if the pushing force applied to the score portion is insufficient, the score portion may not be fully opened. In this case, after the tab is bent back to the original position, it is necessary to raise the tab again. Therefore, when the bendability of the tab is low, the joint portion of the tab with the rivet cannot withstand the above-described repetition of the raising operation and the bending-back operation, and the tab is torn off and detached from the can lid. I do.

  Conventionally, the tab is manufactured from a JIS A5082 alloy plate or a JIS A5182 alloy plate. However, in recent years, for the purpose of cost reduction, there has been a demand for a thinner aluminum alloy plate used for manufacturing a tab. In order to sufficiently secure the strength of the tab obtained while reducing the thickness of the aluminum alloy plate, it is necessary to increase the strength of the aluminum alloy plate as the material. However, since a high-strength aluminum alloy plate has low bendability, there is a high possibility that the tab is torn off due to repetition of the raising operation and the bending-back operation, and the tab is detached from the can lid.

  Therefore, an aluminum alloy plate having both high strength and excellent bendability and a method of manufacturing the same have been studied. For example, Patent Literature 1 discloses an aluminum alloy plate in which the area ratio of the intermetallic compound is suppressed by regulating the amounts of Fe and Mn contributing to an increase in the amount of the intermetallic compound, and the bending property is repeatedly increased. I have. Patent Literature 2 discloses an aluminum alloy plate having improved bendability by defining the number of intermetallic compounds having a maximum of 5 μm or more, the amount of solute Mn, and the homogenization treatment conditions, and a method for producing the same. .

JP-A-2004-183045 JP 2011-225977 A

  However, in the aluminum alloy plates disclosed in Patent Literature 1 and Patent Literature 2, stress tends to concentrate on the interface between the aluminum matrix and the intermetallic compound during bending deformation. As a result, the bendability of the tab may be deteriorated. As described above, in order to obtain an aluminum alloy plate for a tab that achieves both high strength and excellent bendability, it is not sufficient to control the amount of the intermetallic compound, and further improvement is strongly desired. .

  The present invention has been made in view of such a background, and an object of the present invention is to provide an aluminum alloy plate for a tab, which has a low manufacturing cost, can achieve both high strength and excellent bendability, and a method for manufacturing the same.

In one embodiment of the present invention, Si: 0.01 to 0.20% (mass%, the same applies hereinafter), Fe: 0.01 to 0.35%, Cu: 0.005 to 0.15%, Mn: 0 A chemical component containing 0.005 to 0.50%, Mg: 4.0 to 5.0%, and Cr: 0.005 to 0.15%, with the balance being Al and unavoidable impurities;
In the entire range from the plate center to the plate surface in the thickness direction, the Cube orientation density has a texture not less than 1.5 times that of the random orientation sample,
0.2% proof stress is 280-360MPa,
An aluminum alloy plate for a tab having an elongation of 5% or more.

Another embodiment of the present invention is the method for producing an aluminum alloy plate for a tab according to the above embodiment, wherein Si: 0.01 to 0.20% (% by mass, the same applies hereinafter), and Fe: 0.01 to 0. 35%, Cu: 0.005 to 0.15%, Mn: 0.005 to 0.50%, Mg: 4.0 to 5.0%, Cr: 0.005 to 0.15%, Prepare an ingot having a chemical component whose balance is composed of Al and inevitable impurities,
The ingot is heated at 450 to 540 ° C. for 1 to 24 hours to perform a homogenization treatment,
The ingot has an average rolling reduction of 8% to 40% per pass from the time when the thickness of the ingot falls below 150 mm to the end, the thickness at the end is 20 to 32 mm, and the temperature at the end of the ingot. Is 400-500 ° C. to perform multiple passes of hot rough rolling,
Next, a plurality of passes of hot finish rolling are performed such that the strain rate in the first pass is 1 to 25 / sec and the plate temperature at the end is 310 to 390 ° C., so that the plate surface extends from the plate center in the thickness direction. In the entire range up to, a hot rolled sheet having a texture in which the Cube orientation density is 8.0 times or more that of the random orientation sample is produced,
Thereafter, a method for producing an aluminum alloy sheet for a tub, wherein the hot-rolled sheet is subjected to cold rolling.

  The aluminum alloy plate for a tab has the specific chemical component. Thereby, strength and elongation suitable as a tab can be easily obtained.

  Further, since the aluminum alloy plate has the strength in the specific range described above, the plate thickness can be reduced more easily than a conventional aluminum alloy plate.

  Further, the aluminum alloy plate has a texture in which the Cube azimuth density is 1.5 times or more that of the random azimuth sample over the entire range from the plate center to the plate surface in the thickness direction. The aluminum alloy plate having a Cube orientation ({001} <100>) orientation density within the above specific range can reduce stress concentration during bending deformation. Therefore, the aluminum alloy plate can suppress the generation and propagation of a crack that is a starting point of tab tearing, and can suppress the detachment of the tab due to the repetition of the initiating operation and the bending back operation.

  As described above, the aluminum alloy plate has the specific chemical composition and texture, and the 0.2% proof stress and elongation are within the specific ranges, so that the aluminum alloy plate has high strength and excellent bendability. Can be compatible.

  Further, the method of manufacturing the aluminum alloy sheet, by setting the conditions of the hot rough rolling and the hot finish rolling in the above specific range, between passes during hot rough rolling, and during hot finish rolling. Recrystallization occurring between passes or the like can be suppressed. As a result, the hot rolled sheet having a high Cube orientation density can be manufactured. Then, by performing cold rolling on the hot-rolled sheet, the Cube orientation density of the aluminum alloy sheet can be easily adjusted to the specific range.

  Further, according to the manufacturing method, the Cube orientation density of the hot-rolled sheet can be sufficiently increased. Therefore, it is not necessary to increase the Cube orientation density by performing intermediate annealing between the end of hot finish rolling and the end of cold rolling. Therefore, according to the above-mentioned manufacturing method, the effect of reducing the number of heat treatment steps and the manufacturing cost of the above-mentioned aluminum alloy plate can be obtained as compared with the related art.

4 is a photograph as a substitute of a drawing, showing an example of a completely recrystallized structure in Examples. It is a drawing substitute photograph which shows an example of a rolling structure in an Example. It is explanatory drawing of the test method of the bending property of a tab in an Example. It is explanatory drawing of the test method of the strength of a tab in an Example.

  The reasons for limiting the chemical components in the aluminum alloy plate will be described.

Si (silicon): 0.01 to 0.20%
Si forms Mg ₂ Si precipitates when coexisting with Mg. The precipitate has an effect of suppressing the tab from softening at the time of paint baking or the like. By setting the content of Si in the above specific range, softening of the tab can be suppressed.

  When the content of Si is less than 0.01%, the effect of suppressing the softening of the tab becomes insufficient. Further, in this case, it is necessary to use a high-purity aluminum metal at the time of casting, which leads to a decrease in productivity and an increase in manufacturing cost. From the viewpoint of avoiding these problems, the content of Si is preferably 0.03% or more.

  On the other hand, when the content of the Si content is excessively large, the content of the intermetallic compound containing Si increases. If this intermetallic compound is present in a large amount in the aluminum alloy sheet, crack generation and propagation during bending are promoted and randomization of texture is caused. As a result, the bendability of the tab may be deteriorated. From the viewpoint of avoiding these problems, the content of Si is set to 0.20% or less. From the same viewpoint, the content of Si is preferably 0.15% or less.

Fe (iron): 0.01 to 0.35%
Fe has an effect of suppressing the tab from softening at the time of paint baking or the like. By setting the content of Fe to the above specific range, softening of the tab can be suppressed.

  When the content of Fe is less than 0.01%, the effect of suppressing the softening of the tab is insufficient. Further, in this case, it is necessary to use a high-purity aluminum metal at the time of casting, which leads to a decrease in productivity and an increase in manufacturing cost. From the viewpoint of avoiding these problems, the Fe content is preferably 0.05% or more.

  On the other hand, when the content of Fe is excessively large, the amount of the intermetallic compound containing Fe increases. If this intermetallic compound is present in a large amount in the aluminum alloy sheet, crack generation and propagation during bending are promoted and randomization of texture is caused. As a result, the bendability of the tab may be deteriorated. From the viewpoint of avoiding these problems, the content of Fe is set to 0.35% or less. From the same viewpoint, the content of Fe is preferably 0.30% or less.

Cu (copper): 0.005 to 0.15%
Cu has the effect of improving the strength of the tab by solid solution strengthening. By setting the Cu content in the above specific range, the strength of the tab can be sufficiently increased.

  When the content of Cu is less than 0.005%, the effect of increasing the strength of the tab is insufficient. In order to sufficiently increase the strength of the tab, the content of Cu is preferably 0.01% or more.

  On the other hand, when the content of Cu is excessively large, the strength of the aluminum alloy plate becomes excessively high. As a result, there is a possibility that a problem such as cracking of the aluminum alloy plate during forming of the tab or deterioration of bendability of the tab may occur. From the viewpoint of avoiding these problems, the content of Cu is set to 0.15% or less. From the same viewpoint, the content of Cu is preferably 0.13% or less.

Mn (manganese): 0.005 to 0.50%
Mn has an effect of improving the strength of the tab by solid solution strengthening. By setting the content of Mn within the above specific range, the strength of the tab can be sufficiently increased.

  When the content of Mn is less than 0.005%, the effect of increasing the strength of the tab is insufficient. In order to sufficiently increase the strength of the tab, the content of Mn is preferably 0.01% or more.

  On the other hand, when the content of Mn is excessively large, the strength of the aluminum alloy plate becomes excessively high. As a result, there is a possibility that a problem such as cracking of the aluminum alloy plate during forming of the tab or deterioration of bendability of the tab may occur. In this case, the amount of Mn-containing intermetallic compound increases. If this intermetallic compound is present in a large amount in the aluminum alloy sheet, crack generation and propagation during bending are promoted and randomization of texture is caused. As a result, the bending property of the tab is deteriorated. Therefore, from the viewpoint of avoiding these problems, the content of Mn is set to 0.50% or less. From the same viewpoint, the content of Mn is preferably 0.40% or less.

Mg (magnesium): 4.0 to 5.0%
Mg has an effect of improving the strength of the tab by solid solution strengthening. By setting the content of Mg within the above specific range, the strength of the tab can be sufficiently increased.

  When the content of Mg is less than 4.0%, the effect of improving the strength of the tab is insufficient. In order to sufficiently increase the strength of the tab, the content of Mg is preferably 4.2% or more.

  On the other hand, when the content of Mg is excessively large, the strength of the aluminum alloy plate becomes excessively high. As a result, there is a possibility that a problem such as cracking of the aluminum alloy plate during forming of the tab or deterioration of bendability of the tab may occur. Further, in this case, the hot rollability is deteriorated, and the end in the sheet width direction may be broken during rolling. From the viewpoint of avoiding these problems, the content of Mg is set to 5.0% or less. From the same viewpoint, the content of Mg is preferably 4.9% or less.

Cr (chromium): 0.005 to 0.15%
Cr has a function of improving the strength of the tab by solid solution strengthening. By setting the Cr content in the above specific range, the strength of the tab can be sufficiently increased.

  When the content of Cr is less than 0.005%, the effect of improving the strength of the tab is insufficient. In order to sufficiently increase the strength of the tab, the Cr content is preferably 0.01% or more.

  On the other hand, when the content of Cr is excessively large, a coarse intermetallic compound containing Cr is formed. When this intermetallic compound is formed, problems such as the generation and propagation of cracks at the time of bending are promoted, or the strength of the aluminum alloy plate becomes excessively high, etc., thus deteriorating the bendability of the tab. From the viewpoint of avoiding these problems, the content of Cr is set to 0.15% or less. From the same viewpoint, the content of Cr is preferably 0.10% or less.

0.2% proof stress: 280-360MPa
The 0.2% proof stress of the aluminum alloy plate is 280 to 360 MPa. When the 0.2% proof stress is less than 280 MPa, the strength of the tab is insufficient, and the tab may be broken in the middle of the opening. On the other hand, when the 0.2% proof stress exceeds 360 MPa, the strength becomes too high, and the bendability of the tab deteriorates. From the viewpoint of obtaining a tab having appropriate strength, the 0.2% proof stress is preferably 290 to 340 MPa.

Elongation: 5% or more The elongation of the aluminum alloy plate is 5% or more. If the elongation is less than 5%, the tab bendability deteriorates. From the viewpoint of improving the bendability of the tab, the aluminum alloy plate preferably has an elongation of 7% or more.

  In order to increase the bendability of the tab, it is preferable to increase the elongation. However, in order to increase the elongation, it is necessary to restore the texture of the aluminum alloy plate. Then, the recovery of the texture results in a decrease in the proof stress of 0.2% and, consequently, a decrease in the strength of the tab. Therefore, from the viewpoint of the balance between strength and bending property, the elongation is preferably set to 15% or less.

-Texture The aluminum alloy plate has a texture in which the Cube orientation density is 1.5 times or more that of the random orientation sample in the entire range from the plate center to the plate surface in the thickness direction. Thereby, the bendability of the aluminum alloy plate can be improved. In addition, the plate surface refers to a surface on the side that becomes the outer surface of the tab when the tab is manufactured from the aluminum alloy plate. The random orientation sample refers to a sample in which the crystal orientation in the sample is not oriented in a specific direction.

  When the Cube orientation density of the aluminum alloy plate is less than 1.5 times, the relaxation of stress concentration during bending becomes insufficient. As a result, the effect of suppressing the generation and propagation of cracks at the time of bending becomes insufficient, and the bending property is deteriorated. From the viewpoint of improving the bendability, the Cube orientation density is preferably at least 2.0 times that of the random orientation sample.

  In order to improve the bendability of the aluminum alloy plate, it is preferable to increase the Cube orientation density. However, in order to increase the Cube orientation density of the aluminum alloy sheet, it is necessary to adopt a method of reducing the contents of Si, Fe and Mn, or increasing the rolling passes in hot rough rolling. Therefore, if the Cube orientation density of the aluminum alloy plate is excessively increased, the production cost and productivity are rather deteriorated. From the viewpoint of avoiding such a problem, the Cube orientation density of the aluminum alloy plate is preferably 12 times or less that of the random orientation sample.

  Next, a method for manufacturing the aluminum alloy plate will be described. First, an ingot is prepared from an aluminum alloy having the above specific range of chemical components. For producing an ingot, a conventionally known method such as semi-continuous casting can be employed. The obtained ingot is heated at 450 to 540 ° C. for 1 to 24 hours to perform a homogenization treatment. By setting the heating temperature and the heating time within the above specific ranges, homogenization can be sufficiently performed. As a result, the bendability of the tab can be improved.

  If the heating temperature in the homogenization treatment is lower than 450 ° C., the homogenization may be insufficient. As a result, the bendability of the tab may be deteriorated. From the viewpoint of avoiding such a problem, the heating temperature is preferably set to 470 ° C. or higher.

  On the other hand, when the heating temperature in the homogenization treatment exceeds 540 ° C., oxidation or swelling may occur on the surface of the ingot, which may cause deterioration of the surface quality. From the viewpoint of avoiding such a problem, the heating temperature is preferably set to 520 ° C. or lower.

  If the heating time in the homogenization treatment is less than 1 hour, homogenization may be insufficient. As a result, the bendability of the tab may be deteriorated. From the viewpoint of avoiding such a problem, the heating time is preferably set to 2 hours or more.

  On the other hand, when the heating time exceeds 24 hours, the productivity is deteriorated. From the viewpoint of avoiding such a problem, the heating time is preferably set to 12 hours or less.

  After the homogenization treatment, hot rough rolling and hot finish rolling are performed to produce a hot rolled sheet. In the hot rough rolling, a plurality of passes are usually rolled using a reverse rolling mill. At this time, the average of the rolling reduction per pass from the time when the sheet thickness is less than 150 mm until the end of the hot rough rolling is 8 to 40%, the sheet thickness at the end is 20 to 32 mm, and By performing hot rough rolling under the above specific conditions of rolling the ingot by controlling the rolling rate of each pass so that the sheet temperature becomes 400 to 500 ° C., the sheet to be subjected to hot finish rolling The thickness and texture can be set to appropriate ranges.

  When the average of the above-described rolling reductions is less than 8%, the number of rolling passes becomes excessively large, which causes a decrease in the sheet temperature. As a result, the end of the plate may be broken during rolling. From the viewpoint of avoiding such a problem, it is preferable that the average of the draft is 10% or more.

  On the other hand, when the average of the rolling reduction exceeds 40%, the recrystallization driving force increases, and recrystallization between passes is promoted. As a result, the recrystallization texture may be randomized and the tab bendability may be degraded. From the viewpoint of avoiding such a problem, it is preferable that the average of the draft is 30% or less.

  Further, when the sheet thickness at the end of the hot rough rolling is less than 20 mm, the rolling reduction at the time of hot finish rolling becomes small, so that the rolled structure may remain in the hot rolled sheet. As a result, the Cube orientation density of the aluminum alloy plate decreases, and the tab bendability may deteriorate. From the viewpoint of avoiding such a problem, it is preferable to set the plate thickness at the end of the hot rough rolling to 22 mm or more.

  On the other hand, when the sheet thickness at the end is more than 32 mm, the recrystallization driving force is increased due to an increase in the reduction during hot finish rolling. As a result, the recrystallization texture may be randomized and the tab bendability may be degraded. From the viewpoint of avoiding such a problem, it is preferable to set the sheet thickness at the end of the hot rough rolling to 30 mm or less.

  Further, when the sheet temperature at the end of the hot rough rolling is lower than 400 ° C., the end of the sheet may be broken during hot finish rolling because the sheet temperature is too low. From the viewpoint of avoiding such a problem, the sheet temperature at the end of the hot rough rolling is preferably set to 420 ° C. or higher.

  On the other hand, if the plate temperature at the end of hot rough rolling exceeds 500 ° C., the recrystallization driving force increases. As a result, the recrystallized texture is randomized, and the bendability of the tab deteriorates. From the viewpoint of avoiding such a problem, it is preferable to set the sheet temperature at the end of the hot rough rolling to 490 ° C or lower.

  In hot finish rolling, rolling is usually performed in a plurality of passes using a tandem mill. The hot finish rolling is performed such that the strain rate in the first pass is 1 to 25 / sec, and the temperature of the hot rolled sheet at the end of the hot finish rolling is 310 to 390 ° C. By performing the hot finish rolling under the above specific conditions, the thickness and texture of the hot rolled sheet can be adjusted to appropriate ranges.

  When the strain rate in the first pass in the hot finish rolling is less than 1 / sec, the Cube orientation density decreases due to the progress of recrystallization between passes. As a result, the bendability of the tab may be deteriorated. From the viewpoint of avoiding such a problem, the strain rate in the first pass is preferably set to 5 / sec or more.

  On the other hand, when the strain rate in the first pass exceeds 25 / sec, the plate surface is roughened due to insufficient lubrication, and the surface quality is reduced. From the viewpoint of avoiding such a problem, it is preferable to set the strain rate in the first pass to 20 / sec or less.

  If the temperature of the hot-rolled sheet at the end of the hot finish rolling is lower than 310 ° C., a rolled structure remains in the hot-rolled sheet, causing a decrease in the Cube orientation density. As a result, the bendability of the tab may be deteriorated. From the viewpoint of avoiding such a problem, it is preferable to set the temperature of the hot-rolled sheet at the end of the hot finish rolling to 320 ° C. or higher.

  On the other hand, when the temperature of the hot rolled sheet at the end of hot finish rolling exceeds 390 ° C., lubrication is insufficient because the temperature during rolling is high. As a result, the plate surface is roughened, and the surface quality is reduced. From the viewpoint of avoiding such a problem, the temperature of the hot-rolled sheet at the end of the hot finish rolling is preferably set to 370 ° C or lower.

  By performing the hot rough rolling and the hot finish rolling under the above-mentioned specific conditions, the hot rolling in which the Cube orientation density is 8.0 times or more that of the random orientation sample in the entire range from the plate center to the plate surface in the thickness direction. A plate can be made. By controlling the texture of the hot-rolled sheet within the specific range, the Cube orientation density of the aluminum alloy sheet can be increased. As a result, an aluminum alloy plate having high flexibility can be easily manufactured.

  When the Cube orientation density of the hot-rolled sheet is less than 8.0 times the random orientation, it may be difficult to make the Cube orientation density of the aluminum alloy sheet in the specific range. From the viewpoint of avoiding such a problem, it is preferable that the Cube orientation density of the hot-rolled sheet be 10 times or more that of the random orientation sample.

  In order to increase the Cube orientation density of the aluminum alloy sheet, it is preferable to increase the Cube orientation density of the hot-rolled sheet. However, in order to increase the Cube orientation density of the hot-rolled sheet, it is necessary to adopt a method of reducing the contents of Si, Fe and Mn, or increasing the number of rolling passes in hot rough rolling. Therefore, if the Cube orientation density of the hot rolled sheet is excessively increased, the production cost and productivity may be deteriorated. From the viewpoint of avoiding such a problem, it is preferable that the Cube orientation density of the hot-rolled sheet be 60 times or less that of the random orientation sample.

  After performing hot finish rolling, cold rolling is performed on the hot rolled sheet. At this time, the intermediate annealing may be performed on the hot-rolled sheet as necessary between the completion of the hot finish rolling and the cold rolling. When the hot rough rolling and the hot finish rolling are performed under the above specific conditions, the cold rolling can be performed without performing the intermediate annealing.

  Cold rolling is performed such that the total draft is 75 to 95%. Thereby, an aluminum alloy plate having both high strength and flexibility can be obtained. When the total draft is less than 75%, the strength of the finally obtained tab is insufficient, and there is a possibility that the tab may be broken in the middle of the opening. From the viewpoint of avoiding such a problem, it is preferable to set the total draft of the cold rolling to 80% or more.

  On the other hand, when the total draft exceeds 95%, problems such as a decrease in the Cube orientation density or an excessive increase in the strength of the aluminum alloy plate may occur. As a result, the bendability of the tab may be deteriorated. From the viewpoint of avoiding such a problem, it is preferable to set the total rolling reduction of the cold rolling to 90% or less.

  After the completion of the cold rolling, a coating treatment may be performed as necessary. The coating baking temperature can be appropriately determined according to the physical properties of the coating film. Usually, if the baking temperature is in the range of 240 to 300 ° C., there is no possibility that the bendability or strength of the obtained tab is adversely affected.

  Examples of the aluminum alloy plate will be described below. It should be noted that the present invention is not limited to this embodiment, and can be appropriately modified without impairing the spirit of the present invention.

  In this example, first, an ingot of an aluminum alloy (alloys A to P) having the chemical components shown in Table 1 was manufactured by a DC casting method. The ingot was subjected to homogenization treatment, hot rough rolling and hot finish rolling under the conditions shown in Table 2 to produce a hot rolled sheet. Next, the hot-rolled sheet was subjected to cold rolling under the conditions shown in Table 2 to produce an aluminum alloy sheet (test materials 1 to 42) having a sheet thickness of 0.33 mm. In the hot rough rolling, a plurality of passes were rolled using a reverse rolling mill. The hot finish rolling was performed using a four-stand tandem mill. In the cold rolling, rolling was performed in 4 to 7 passes using a single mill.

<Evaluation of hot rolled sheet>
A part of the hot rolled sheet was sampled during the production of each test material, and the structure was observed and the texture was analyzed.

-Structure observation The hot-rolled plate was polished using the Barker method, and the plate cross section (L-ST plane) parallel to the rolling direction was observed. The results are shown in Tables 3 and 4. In addition, in the column of "structure observation" in Tables 3 and 4, the symbol of A was described when the structure was observed to be a completely recrystallized structure, and the symbol B was displayed when the rolled structure remained as a result of the structure observation. .

  The complete recrystallized structure is composed of many granular crystals, for example, as shown in FIG. On the other hand, the rolling structure is a fibrous structure extending in the rolling direction, for example, as shown in FIG. 1 and 2, the vertical direction is the thickness direction (ST direction), and the horizontal direction is the rolling direction (L direction).

-Analysis of texture The Cube orientation density of the above-mentioned plate cross section (L-ST plane) where the structure was observed was calculated by SEM-EBSD (scanning electron microscope-electron beam back scattering diffraction). Then, the Cube orientation densities in the entire range from the center in the thickness direction to the plate surface were averaged. This average value was converted into a magnification for the Cube azimuth density of the random azimuth sample which was separately calculated, and is shown in the column of “Cube azimuth density” in Tables 3 and 4. The Cube azimuth density was calculated from all crystal grains having a tilt angle of 15 ° or less from {001} <100>, which is a plane index of the Cube azimuth. Aluminum powder having no texture was used as the random orientation sample. For the analysis of the texture, OIM (Orientation Imaging Microscopy) manufactured by TSL was used.

<Evaluation of test materials>
For each test material, the tensile properties, texture, tab bendability, tab strength and formability were evaluated.

-Tensile properties A JIS No. 5 tensile test piece was collected from each test material, and the coating film was removed. Thereafter, a tensile test was performed in accordance with the provisions of JIS Z2241, and 0.2% proof stress and elongation were evaluated. In addition, the test piece was sampled so that the longitudinal direction was parallel to the rolling direction.

Texture The Cube orientation densities of the plate surface and the plate central surface in the thickness direction (ST direction) were measured by X-ray diffraction. Then, the average value of the Cube azimuth density on the plate surface and the Cube azimuth density on the center surface of the plate was calculated. This average value was converted into a magnification for the Cube azimuth density of the random azimuth sample which was separately calculated, and is shown in the column of “Cube azimuth density” in Tables 3 and 4. Note that the Cube orientation density was calculated from all crystal grains having a tilt angle of 15 ° or less from {001} <100>, which is the plane index of the Cube orientation, as in the evaluation of the hot-rolled sheet. In addition, an aluminum powder having no texture was used as a random orientation sample.

-Formability From each test material, a DRT company type stub was molded using a mold, and the presence or absence of cracking during processing was evaluated. The results are shown in Tables 3 and 4. In Tables 3 and 4, in the column of "formability", the symbol of A is shown when no cracks occurred, and the symbol of B when cracks occurred.

-Tab bendability After forming the stay-ion tab 1 in the same manner as described above, the tab 1 was attached to the rivet 21 of the can lid 2 as shown in FIG. After the tab 1 was raised by hand to open the score portion 22 normally, the tab 1 was bent until the tab 1 fell to the opposite side of the original position, that is, the score portion 22 side (see arrow 101). Thereafter, the tab 1 was bent back to the original position (see arrow 102). The raising operation and the bending-back operation were repeatedly performed to evaluate whether or not the tab was torn. The results are shown in Tables 3 and 4. In the column of "bendability" in Tables 3 and 4, a symbol A is shown when the tab 1 is not broken when the tab 1 has reciprocated two and a half times, and a symbol B is shown when the tab 1 has been broken less than two and a half reciprocations. did.

Tab Strength After the tab 1 was attached to the rivet 21 of the can lid 2 in the same manner as described above, the tab 1 was rotated 90 ° around the rivet 21 (arrow 103) as shown in FIG. At this time, the load was applied only to the tab 1. In this state, the tab was raised by the can open tester, and the load until the tab 1 was broken was measured. The results are shown in Tables 3 and 4. In addition, in the columns of “tab strength” in Tables 3 and 4, the symbols of A when the load when the tab was broken were 30 N or more and B when the load was less than 30 N were described.

  As shown in Tables 1 to 3, Test Materials 1 to 20 had the chemical components and textures in the specific ranges described above, and the tensile strength and elongation were in the specific ranges. Therefore, these test materials were able to achieve both high strength and flexibility. And the tabs produced from these test materials had good moldability, bendability and strength.

  As shown in Table 1, Table 2, and Table 4, in the test materials 21 and 22, since either the Si amount or the Fe amount was larger than the above specific range, a large amount of the intermetallic compound was formed. As a result, these test materials had poor tab bendability.

  In Test Materials 23, 25, and 27, since any of the Cu content, the Mn content, and the Mg content was smaller than the above specific range, the tensile strength was lower than the above specific range. Therefore, these test materials had low tab strength.

The tensile strength of the test material 24 was higher than the specific range because the amount of Cu was larger than the specific range. Therefore, the test material 24 had poor tab formability and bendability.
Since the Mn amount of the test material 26 was larger than the above specific range, the tensile strength was higher than the above specific range. Therefore, the test material 26 had poor tab bendability.

  Since the amount of Mg of the test material 28 was larger than the above-mentioned specific range, cracks occurred at the plate edge during hot rolling. Therefore, the production of the test material 28 was stopped without performing cold rolling.

Since the Cr content of the test material 29 was smaller than the specific range, the tensile strength was lower than the specific range. Therefore, the test material 29 had a low tab strength.
Since the amount of Cr was larger than the above-mentioned specific range, the tensile strength of the test material 30 became higher than the above-mentioned specific range. Further, a coarse intermetallic compound was formed on the test material 30. Therefore, the test material 30 had poor tab bendability.

  Since the homogenization temperature of the test material 31 was higher than the above specific range, the surface was strongly oxidized and the surface quality was deteriorated. Therefore, the production of the test material 31 was stopped without performing the steps after the hot rolling.

  Since the test material 32 had an average rolling reduction during hot rough rolling that was smaller than the above specific range, the number of passes in hot rough rolling increased, and the sheet temperature at the end of hot rough rolling was lower than the above specific range. Lower than. As a result, cracks occurred at the plate edge during hot finish rolling. Therefore, the production of the test material 32 was stopped without performing cold rolling.

  In the test material 33, the average of the draft in the hot rough rolling was larger than the above specific range. As a result, as a result of the progress of recrystallization during hot rolling, the Cube orientation density of the test material 33 became lower than the above specific range. Therefore, the test material 33 had poor tab flexibility.

  In the test material 34, the plate temperature at the end of the hot rough rolling was higher than the above specific range. As a result, recrystallization during hot rolling progressed, so that the Cube orientation density of the test material 34 became lower than the above specific range. As a result, the test material 34 had poor tab bendability.

  Since the thickness of the test material 35 at the end of the hot rough rolling was smaller than the above specific range, the amount of reduction during the hot finish rolling was insufficient. As a result, as a result of the rolled structure remaining on the hot-rolled sheet, the Cube orientation density of the test material 35 became lower than the above specific range. Therefore, the test material 35 had poor tab bendability.

  Since the thickness of the test material 36 at the end of the hot rough rolling was larger than the above-described specific range, the rolling reduction at the time of the hot finish rolling was large. As a result, as a result of the progress of recrystallization during hot rolling, the Cube orientation density of the test material 36 became lower than the above specific range. Therefore, the test material 36 had poor tab bendability.

  In the test material 37, the strain rate at the first stand (first pass) of the hot finish rolling was smaller than the above specific range. As a result, as a result of the progress of recrystallization during hot rolling, the Cube orientation density of the test material 37 became lower than the above specific range. Therefore, the test material 37 had poor tab flexibility.

  The test material 38 had insufficient lubrication during rolling because the strain rate at the first stand of the hot finish rolling was higher than the above specific range. As a result, the plate surface became rough, and the surface quality was reduced. Therefore, the production of the test material 38 was stopped without performing cold rolling.

  In Test Material 39, since the temperature of the hot-rolled sheet was lower than the above specific range, recrystallization could not be completed, and the rolled structure remained in the hot-rolled sheet. As a result, the Cube orientation density of the test material 39 was lower than the above specific range. Therefore, the test material 39 had poor tab bendability.

  In the test material 40, the lubrication during rolling was insufficient because the temperature of the hot-rolled sheet was higher than the above specific range. As a result, the plate surface became rough, and the surface quality was reduced. Therefore, the production of the test material 40 was stopped without performing cold rolling.

  Since the total rolling reduction in the cold rolling of the test material 41 was smaller than the above specific range, the tensile strength was lower than the above specific range. As a result, the test material 41 had low tab strength.

  Since the total reduction in the cold rolling of the test material 42 was higher than the above specific range, the tensile strength was higher than the above specific range. As a result, the test material 42 had poor tab bendability.

1 tab 2 can lid
21 Rivets 22 Score section

Claims (5)

Si: 0.01 to 0.20% (mass%, the same applies hereinafter), Fe: 0.01 to 0.35%, Cu: 0.005 to 0.15%, Mn: 0.005 to 0.50% , Mg: 4.0 to 5.0% and Cr: 0.005 to 0.15%, the balance being a chemical component consisting of Al and unavoidable impurities;
In the entire range from the plate center to the plate surface in the thickness direction, the Cube orientation density has a texture not less than 1.5 times that of the random orientation sample,
0.2% proof stress is 280-360MPa,
An aluminum alloy plate for a tab having an elongation of 5% or more.   The aluminum alloy for a tab according to claim 1, wherein the Cube orientation density has the texture of 2.0 times or more and 12.0 times or less of the random orientation sample in the entire range from the plate center to the plate surface in the thickness direction. Board. It is a manufacturing method of the aluminum alloy plate for tabs of Claim 1 or 2, Comprising:
Si: 0.01 to 0.20% (mass%, the same applies hereinafter), Fe: 0.01 to 0.35%, Cu: 0.005 to 0.15%, Mn: 0.005 to 0.50% , Mg: 4.0 to 5.0%, Cr: 0.005 to 0.15%, the remainder being provided with an ingot having a chemical component consisting of Al and unavoidable impurities,
The ingot is heated at 450 to 540 ° C. for 1 to 24 hours to perform a homogenization treatment,
The ingot has an average rolling reduction of 8% to 40% per pass from the time when the thickness of the ingot falls below 150 mm to the end, the thickness at the end is 20 to 32 mm, and the temperature at the end of the ingot. Is 400-500 ° C. to perform multiple passes of hot rough rolling,
Next, a plurality of passes of hot finish rolling are performed such that the strain rate in the first pass is 1 to 25 / sec and the plate temperature at the end is 310 to 390 ° C., so that the plate surface extends from the plate center in the thickness direction. In the entire range up to, a hot rolled sheet having a texture in which the Cube orientation density is 8.0 times or more that of the random orientation sample is produced,
Thereafter, a cold rolling is performed on the hot-rolled sheet, and a method for producing an aluminum alloy sheet for a tub.   The aluminum for tabs according to claim 3, wherein the hot-rolled sheet having the texture whose Cube orientation density is 10 to 60 times that of the random orientation sample is produced at all positions in the thickness direction from the plate center to the plate surface. Manufacturing method of alloy sheet.   The method for producing an aluminum alloy sheet for tabs according to claim 3 or 4, wherein a total draft in the cold rolling is 75 to 95%.