CN107923005B - Aluminum alloy plate for tab and method for manufacturing same - Google Patents
Aluminum alloy plate for tab and method for manufacturing same Download PDFInfo
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- CN107923005B CN107923005B CN201680049761.3A CN201680049761A CN107923005B CN 107923005 B CN107923005 B CN 107923005B CN 201680049761 A CN201680049761 A CN 201680049761A CN 107923005 B CN107923005 B CN 107923005B
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C21/00—Alloys based on aluminium
- C22C21/06—Alloys based on aluminium with magnesium as the next major constituent
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22F—CHANGING THE PHYSICAL STRUCTURE OF NON-FERROUS METALS AND NON-FERROUS ALLOYS
- C22F1/00—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working
- C22F1/04—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working of aluminium or alloys based thereon
- C22F1/047—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working of aluminium or alloys based thereon of alloys with magnesium as the next major constituent
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22F—CHANGING THE PHYSICAL STRUCTURE OF NON-FERROUS METALS AND NON-FERROUS ALLOYS
- C22F1/00—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working
Abstract
The invention provides an aluminum alloy plate for a pull ring and a manufacturing method thereof, wherein the aluminum alloy plate is low in manufacturing cost and can achieve high strength and excellent bending property. The aluminum alloy plate for a tab comprises: a chemical composition comprising Si: 0.01 to 0.20 mass%, Fe: 0.01 to 0.35 mass%, Cu: 0.005-0.15 mass%, Mn: 0.005-0.50 mass%, Mg: 4.0 to 5.0 mass% and Cr: 0.005 to 0.15 mass%, the balance being Al and unavoidable impurities; and a texture in which the Cube orientation density is 1.5 times or more that of the randomly oriented sample over the entire range from the center of the plate to the surface of the plate in the thickness direction. The 0.2% proof stress is 280-360 MPa, and the elongation is more than 5%.
Description
Technical Field
The present invention relates to an aluminum alloy sheet for a tab suitable as a material for a tab to be attached to a can lid and a method for producing the same.
Background
Steel cans or aluminum cans are widely used as packaging containers for beverages or 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, a can lid of a beverage can often has either a pull-tab method of removing a score portion of the can lid together with a tab or a leave-on tab method of pressing down the score portion of the can lid with the tab. In recent years, can lids of the pull-tab retention type have become mainstream from the viewpoint of environmental problems and the like.
The tab is mounted on a rivet formed in the can end. For example, in the case of opening a can lid of the pull-tab retention type, the scored portion of the can lid is pressed toward the inside of the can by the principle of leverage by pulling up the pull tab. However, if the pressing force applied to the scored portion is insufficient, the scored portion may not be fully opened. In this case, the tab needs to be bent back to the original position and then pulled up again. Therefore, when the bendability of the tab is low, the joint portion of the tab and the rivet cannot completely withstand the repetition of the above-described pulling-up operation and bending-back operation, and a problem occurs in that the tab tears and separates from the can lid.
Conventionally, a tab is made of a JIS a5082 alloy sheet or a JIS a5182 alloy sheet. However, in recent years, thinning of aluminum alloy sheets used for manufacturing tabs has been demanded for the purpose of cost reduction. In order to sufficiently ensure the obtained tab strength while thinning the aluminum alloy sheet, it is necessary to increase the strength of the aluminum alloy sheet as a raw material. However, since the high-strength aluminum alloy sheet has low bendability, the tab is torn by repeating the pulling-up operation and the bending-back operation, and the possibility of detachment from the can lid is increased.
Therefore, an aluminum alloy sheet and a method for producing the same are being studied, which are both high in strength and excellent in bendability. For example, patent document 1 discloses an aluminum alloy sheet in which the area ratio of the intermetallic compound is suppressed by limiting the amount of Fe and the amount of Mn contributing to increase of the intermetallic compound, and the repeated bendability is improved. Patent document 2 discloses an aluminum alloy sheet having improved bendability by specifying the number of intermetallic compounds of at most 5 μm, the amount of solid-solution Mn, and the homogenization treatment conditions, and a method for producing the same.
Documents of the prior art
Patent document
Patent document 1: japanese laid-open patent publication No. 2004-183045
Patent document 2: japanese patent laid-open publication No. 2011-225977
Disclosure of Invention
Problems to be solved by the invention
However, the aluminum alloy sheets disclosed in patent documents 1 and 2 tend to concentrate stress on the interface between the aluminum matrix and the intermetallic compound during bending deformation. As a result, the bending property of the tab may be deteriorated. In order to obtain an aluminum alloy sheet for a tab having both high strength and excellent bendability, it is not sufficient to control the amount of the intermetallic compound alone, and further improvement is strongly desired.
The present invention has been made in view of the above circumstances, and an object thereof is to provide an aluminum alloy sheet for a tab which is low in production cost and can achieve both high strength and excellent bendability, and a production method thereof.
Means for solving the problems
One aspect of the present invention provides an aluminum alloy sheet for a tab, including:
a chemical composition containing Si (silicon): 0.01 to 0.20 mass%, Fe (iron): 0.01 to 0.35 mass%, Cu (copper): 0.005-0.15 mass%, Mn (manganese): 0.005-0.50 mass%, Mg (magnesium): 4.0 to 5.0 mass% and Cr (chromium): 0.005 to 0.15 mass%, the balance being Al (aluminum) and unavoidable impurities; and
texture (Japanese texture coated article) having Cube orientation density 1.5 times or more as high as that of the randomly oriented sample over the entire range from the center to the surface of the plate in the thickness direction,
0.2% proof stress is 280-360 MPa,
the elongation is 5% or more.
Another aspect of the present invention provides a method of manufacturing an aluminum alloy sheet for tab,
preparing an ingot having a chemical composition comprising Si: 0.01 to 0.20 mass%, Fe: 0.01 to 0.35 mass%, Cu: 0.005-0.15 mass%, Mn: 0.005-0.50 mass%, Mg: 4.0-5.0 mass%, Cr: 0.005 to 0.15 mass%, the balance being Al and unavoidable impurities,
heating the ingot at 450-540 ℃ for 1-24 hours to perform homogenization treatment,
the ingot is subjected to hot rough rolling in a plurality of passes so that the average reduction per pass from a plate thickness of less than 150mm to the end is 8 to 40%, the plate thickness at the end is 20 to 32mm, and the plate temperature at the end is 400 to 500 ℃,
then, a hot-rolled sheet having a texture in which the Cube orientation density is 8.0 times or more the randomly oriented sample over the entire range from the center to the surface of the sheet in the thickness direction is produced by performing a plurality of passes of hot finish rolling so that the strain rate of the first pass is 1 to 25/sec and the sheet temperature at the end is 310 to 390 ℃,
thereafter, the hot-rolled sheet is cold-rolled.
Effects of the invention
The aluminum alloy sheet for a tab has the specific chemical composition. This makes it possible to easily obtain strength and elongation suitable for a tab.
Further, since the aluminum alloy sheet has the strength within the specific range, the sheet thickness can be easily reduced as compared with the conventional aluminum alloy sheet.
Further, the aluminum alloy sheet had a texture in which the Cube orientation density was 1.5 times or more the random orientation sample over the entire range from the center of the sheet to the surface of the sheet in the thickness direction. The aluminum alloy sheet having Cube orientation ({001} < 100 >) orientation density in the specific range can alleviate stress concentration in bending deformation. Therefore, the aluminum alloy sheet can suppress the occurrence or development of cracks that become starting points of tab tearing, and can suppress tab detachment due to repetition of the pull-up operation and the kick-back operation.
In this way, the aluminum alloy sheet has the specific chemical composition and texture, and the 0.2% proof stress and elongation are within the specific ranges, whereby high strength and excellent bendability can be achieved at the same time.
In the method for producing an aluminum alloy sheet, by setting the conditions of the hot rough rolling and the hot finish rolling to the specific ranges, recrystallization occurring between passes during hot rough rolling, between passes during hot finish rolling, and the like can be suppressed. As a result, the hot-rolled sheet having a high Cube orientation density can be produced. Further, by cold rolling the hot-rolled sheet, the Cube orientation density of the aluminum alloy sheet can be easily set to the specific range.
In addition, according to the manufacturing method, the Cube orientation density of the hot-rolled sheet can be sufficiently increased. Therefore, it is not necessary to perform intermediate annealing after the finish hot-rolling and before the finish cold-rolling to increase the Cube orientation density. Therefore, according to the manufacturing method, the manufacturing cost of the aluminum alloy sheet can be reduced compared to the conventional method in which the heat treatment step is eliminated.
Drawings
FIG. 1 is a photograph showing an alternative drawing showing an example of a completely recrystallized structure in an example.
FIG. 2 is a photograph showing an example of a rolled structure in an alternative drawing.
FIG. 3 is a diagram illustrating a method of testing the bendability of the tab in the example.
FIG. 4 is a diagram illustrating a method of testing the tab strength of the embodiment.
Detailed Description
The reason for limiting the chemical composition of the aluminum alloy sheet will be described.
Si (silicon): 0.01 to 0.20% by mass
Si forms Mg in the presence of Mg2Si precipitates. The precipitates have an effect of suppressing the softening of the tab during coating and baking. By setting the Si content to the above-specified range, the tab can be suppressed from softening.
When the content of Si is less than 0.01 mass%, the effect of suppressing the softening of the tab is insufficient. In this case, since it is necessary to use a high-purity aluminum ingot in casting, productivity is deteriorated and manufacturing cost is increased. From the viewpoint of avoiding these problems, the content of Si is preferably 0.03 mass% or more.
On the other hand, when the content of the Si amount is too large, the content of the intermetallic compound containing Si increases. When the intermetallic compound is present in a large amount in the above aluminum alloy sheet, randomization of texture is caused in addition to promotion of generation or development of cracks at the time of bending. As a result, the bending property of the tab may be deteriorated. From the viewpoint of avoiding these problems, the content of Si is set to 0.20 mass% or less. From the same viewpoint, the content of Si is preferably 0.15 mass% or less.
Fe (iron): 0.01 to 0.35% by mass
Fe has an effect of suppressing the softening of the tab during coating and baking. By setting the Fe content to the above-specified range, the tab softening can be suppressed.
If the Fe content is less than 0.01 mass%, the effect of suppressing the softening of the tab is insufficient. In this case, since it is necessary to use a high-purity aluminum ingot in casting, productivity is deteriorated and manufacturing cost is increased. From the viewpoint of avoiding these problems, the content of Fe is preferably 0.05 mass% or more.
On the other hand, when the content of Fe is too large, the intermetallic compound containing Fe increases. When the intermetallic compound is present in a large amount in the above aluminum alloy sheet, randomization of texture is caused in addition to promotion of generation or development of cracks at the time of bending. As a result, the bending property of the tab may be deteriorated. From the viewpoint of avoiding these problems, the content of Fe is set to 0.35 mass% or less. From the same viewpoint, the content of Fe is preferably 0.30 mass% or less.
Cu (copper): 0.005 to 0.15% by mass
Cu has an effect of improving the tab strength by solid solution strengthening. By setting the Cu content to the above-specified range, the strength of the tab can be sufficiently improved.
When the Cu content is less than 0.005 mass%, the effect of improving the tab strength is insufficient. In order to sufficiently improve the strength of the tab, the content of Cu is preferably 0.01 mass% or more.
On the other hand, if the Cu content is too high, the strength of the aluminum alloy sheet becomes too high. As a result, the above-mentioned problems such as breakage of the aluminum alloy sheet and deterioration of the bendability of the tab may occur in the forming of the tab. From the viewpoint of avoiding these problems, the content of Cu is set to 0.15 mass% or less. From the same viewpoint, the content of Cu is preferably 0.13 mass% or less.
Mn (manganese): 0.005 to 0.50% by mass
Mn has an effect of improving the tab strength by solid solution strengthening. By setting the Mn content within the above-specified range, the tab strength can be sufficiently improved.
When the Mn content is less than 0.005 mass%, the effect of improving the tab strength is insufficient. In order to sufficiently improve the tab strength, the content of Mn is preferably 0.01 mass% or more.
On the other hand, if the Mn content is too high, the strength of the aluminum alloy sheet becomes too high. As a result, the above-described problems such as breakage of the aluminum alloy sheet and deterioration of the bendability of the tab may occur in the forming of the tab. In this case, the number of Mn-containing intermetallic compounds increases. When the intermetallic compound is present in a large amount in the above aluminum alloy sheet, randomization of texture is caused in addition to promotion of generation or development of cracks at the time of bending. 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 mass% or less. From the same viewpoint, the Mn content is preferably 0.40 mass% or less.
Mg (magnesium): 4.0 to 5.0% by mass
Mg has an effect of improving the tab strength by solid solution strengthening. By setting the Mg content in the above-specified range, the strength of the tab can be sufficiently improved.
When the Mg content is less than 4.0 mass%, the effect of improving the tab strength is insufficient. The content of Mg is preferably 4.2 mass% or more in order to sufficiently improve the tab strength.
On the other hand, if the Mg content is too large, the strength of the aluminum alloy sheet becomes too high. As a result, the above-described problems such as breakage of the aluminum alloy sheet and deterioration of the bendability of the tab may occur in the forming of the tab. In addition, in this case, hot rolling property is deteriorated, and there is a possibility that an end portion in the plate width direction is broken during rolling. From the viewpoint of avoiding these problems, the Mg content is set to 5.0 mass% or less. From the same viewpoint, the Mg content is preferably 4.9 mass% or less.
Cr (chromium): 0.005 to 0.15% by mass
Cr has an effect of improving the tab strength by solid solution strengthening. By setting the Cr content within the above-specified range, the tab strength can be sufficiently improved.
When the content of Cr is less than 0.005 mass%, the effect of improving the tab strength is insufficient. The content of Cr is preferably 0.01 mass% or more in order to sufficiently improve the tab strength.
On the other hand, if the Cr content is too high, coarse intermetallic compounds containing Cr are formed. If the intermetallic compound is formed, problems such as promotion of generation and development of cracks at the time of bending, or excessively high strength of the aluminum alloy sheet occur, and the bendability of the tab is deteriorated. From the viewpoint of avoiding these problems, the content of Cr is set to 0.15 mass% or less. From the same viewpoint, the content of Cr is preferably 0.10 mass% or less.
0.2% proof stress: 280-360 MPa
The 0.2% proof stress of the aluminum alloy plate is 280-360 MPa. If the 0.2% proof stress is less than 280MPa, the tab strength is insufficient, and the tab may be bent in the middle of opening. On the other hand, when the 0.2% proof stress exceeds 360MPa, the strength becomes too high, and the bendability of the tab deteriorates. From the viewpoint of obtaining a tab having an appropriate strength, the 0.2% proof stress is preferably 290 to 340 MPa.
Elongation percentage: over 5 percent
The elongation of the aluminum alloy sheet is 5% or more. When the elongation is less than 5%, the bendability of the tab is deteriorated. From the viewpoint of improving the bendability of the tab, the elongation of the aluminum alloy sheet is preferably 7% or more.
In order to improve 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 sheet. Moreover, the recovery of texture results in a reduction of 0.2% proof stress, which in turn results in a reduction of tab strength. Therefore, from the viewpoint of balance between strength and bendability, the elongation is preferably 15% or less.
Texture
The aluminum alloy sheet described above has a texture in which Cube orientation density is 1.5 times or more that of a randomly oriented sample throughout the range from the center of the sheet to the surface of the sheet in the thickness direction. This improves the bendability of the aluminum alloy plate. The plate surface refers to a surface on the side of the outer surface of the tab when the tab is produced from the aluminum alloy plate. The random orientation sample is a sample in which the crystal orientation of the sample is not oriented in a specific direction.
When the Cube orientation density of the aluminum alloy sheet is less than 1.5 times, relaxation of stress concentration at the time of bending is insufficient. As a result, the effect of suppressing the generation or development of cracks during bending is insufficient, resulting in deterioration of the bending property. From the viewpoint of improving the bendability, the Cube orientation density is preferably 2.0 times or more as high as that of the randomly oriented sample.
In order to improve the bendability of the aluminum alloy sheet, 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, increasing the number of passes in hot rough rolling, or the like. Therefore, when the Cube orientation density of the aluminum alloy sheet is excessively increased, the manufacturing cost or productivity is rather deteriorated. From the viewpoint of avoiding this problem, the Cube orientation density of the aluminum alloy sheet is preferably 12 times or less of that of the randomly oriented sample.
Next, a method for producing the aluminum alloy sheet will be described. First, an ingot is made of an aluminum alloy having the above-described specific range of chemical composition. The ingot can be produced by a conventionally known method such as semi-continuous casting. The obtained ingot is heated at 450 to 540 ℃ for 1 to 24 hours, and then homogenized. When the heating temperature and the heating time are within the above-described specific ranges, homogenization can be sufficiently performed. As a result, the bendability of the tab can be improved.
In the case where the heating temperature in the homogenization treatment is lower than 450 ℃, homogenization may be insufficient. As a result, the bending property of the tab may be deteriorated. From the viewpoint of avoiding this problem, the heating temperature is preferably 470 ℃ or higher.
On the other hand, in the case where the heating temperature in the homogenization treatment exceeds 540 ℃, oxidation or expansion occurs on the surface of the ingot, possibly resulting in a reduction in surface quality. From the viewpoint of avoiding this problem, the heating temperature is preferably 520 ℃ or lower.
In the case where the heating time in the homogenization treatment is less than 1 hour, homogenization may be insufficient. As a result, the bending property of the tab may be deteriorated. From the viewpoint of avoiding this problem, it is preferable to set the heating time 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 this problem, the heating time is preferably 12 hours or less.
After the homogenization treatment, hot rough rolling and hot finish rolling are performed to produce a hot rolled sheet. In hot rough rolling, rolling is usually performed in a plurality of passes using a reversing mill. In this case, the hot rough rolling is performed under the specific conditions for rolling the ingot by controlling the rolling reduction of each pass so that the average of the reduction per 1 pass from the time when the plate thickness is less than 150mm to the time when the hot rough rolling is completed is 8 to 40%, the plate thickness at the time when the hot rough rolling is completed is 20 to 32mm, and the plate temperature at the time when the hot rough rolling is completed is 400 to 500 ℃.
When the above-mentioned reduction ratio is less than 8% on average, the number of passes becomes too large, and thus the plate temperature is lowered. As a result, the ends of the sheet may be broken during rolling. From the viewpoint of avoiding this problem, it is preferable to set the average reduction ratio to 10% or more.
On the other hand, when the average reduction ratio exceeds 40%, the driving force for recrystallization increases, and recrystallization between passes is promoted. As a result, the recrystallization texture is randomized, and the bendability of the tab may deteriorate. From the viewpoint of avoiding this problem, it is preferable to set the average reduction ratio to 30% or less.
When the plate thickness at the end of hot rough rolling is less than 20mm, the reduction amount at the time of hot finish rolling is reduced, and therefore, a rolled structure may remain in the hot rolled plate. As a result, the Cube orientation density of the aluminum alloy sheet is lowered, and the bending property of the tab is likely to be deteriorated. From the viewpoint of avoiding this problem, it is preferable to set the plate thickness at the end of hot rough rolling to 22mm or more.
On the other hand, when the plate thickness at the end exceeds 32mm, the reduction amount at the time of hot finish rolling is increased, and thus the driving force for recrystallization is increased. As a result, the recrystallization texture is randomized, and the bendability of the tab may deteriorate. From the viewpoint of avoiding this problem, it is preferable to set the plate thickness at the end of hot rough rolling to 30mm or less.
In addition, in the case where the sheet temperature at the end of hot rough rolling is less than 400 ℃, the sheet temperature is excessively low, so that the end portion of the sheet may be cracked during the hot finish rolling. From the viewpoint of avoiding this problem, it is preferable to set the plate temperature at the end of hot rough rolling to 420 ℃ or higher.
On the other hand, when the sheet temperature at the end of hot rough rolling exceeds 500 ℃, the driving force for recrystallization becomes high. As a result, the recrystallized texture is randomized, and the bendability of the tab is deteriorated. From the viewpoint of avoiding this problem, it is preferable to set the plate temperature at the end of hot rough rolling to 490 ℃ or lower.
In the finish hot rolling, rolling is generally performed in a plurality of passes using a tandem rolling mill. The hot finish rolling is performed so that the strain rate of 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 ℃. By performing the finish hot rolling under the above-described specific conditions, the thickness and texture of the hot rolled plate can be set to appropriate ranges.
When the strain rate in the first pass in the finish hot rolling is less than 1/sec, the Cube orientation density decreases by recrystallization proceeding between passes. As a result, the bending property of the tab may be deteriorated. From the viewpoint of avoiding this problem, it is preferable to set the strain rate in the first pass to 5/sec or more.
On the other hand, when the strain rate in the first pass exceeds 25/sec, the lubrication is insufficient to roughen the plate surface, resulting in a decrease in surface quality. From the viewpoint of avoiding this problem, it is preferable to set the strain rate in the first pass to 20/sec or less.
When the temperature of the hot-rolled sheet after the finish hot-rolling is lower than 310 ℃, the rolled structure remains in the hot-rolled sheet, resulting in a decrease in Cube orientation density. As a result, the bending property of the tab may be deteriorated. From the viewpoint of avoiding this problem, it is preferable to set the temperature of the hot-rolled sheet at the end of the hot finish rolling to 320 ℃ or higher.
On the other hand, when the temperature of the hot-rolled sheet at the end of the finish hot rolling exceeds 390 ℃, the temperature during rolling is high, and therefore, lubrication is insufficient. As a result, the plate surface becomes rough, resulting in a reduction in surface quality. From the viewpoint of avoiding this problem, it is preferable to set the temperature of the hot-rolled sheet at the end of the finish hot rolling to 370 ℃.
By performing the hot rough rolling and the hot finish rolling under the above-described specific conditions, a hot-rolled sheet having a Cube orientation density of 8.0 times or more that of the randomly oriented sample can be produced over the entire range from the center of the sheet to the surface of the sheet in the thickness direction. By controlling the texture of the hot-rolled sheet within the above-specified range, the Cube orientation density of the aluminum alloy sheet can be increased. As a result, an aluminum alloy sheet having high bendability can be easily produced.
When the Cube orientation density of the hot-rolled sheet is less than 8.0 times as high as the random orientation, it may be difficult to set the Cube orientation density of the aluminum alloy sheet in the above-described specific range. From the viewpoint of avoiding this problem, it is preferable to set the Cube orientation density of the hot-rolled sheet to 10 times or more of that of the randomly oriented 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 passes in hot rough rolling. Therefore, when the Cube orientation density of the hot-rolled sheet is to be excessively increased, the manufacturing cost or productivity may be deteriorated. From the viewpoint of avoiding this problem, it is preferable to set the Cube orientation density of the hot-rolled sheet to 60 times or less of that of the randomly oriented sample.
After the hot finish rolling, the hot rolled sheet is cold rolled. In this case, after the finish hot rolling is completed, intermediate annealing may be performed on the hot-rolled sheet as necessary until the cold rolling is performed. When the hot rough rolling and the hot finish rolling are performed under the above-described specific conditions, the cold rolling can be performed without performing the intermediate annealing.
The cold rolling is performed so that the total reduction ratio is 75 to 95%. Thus, an aluminum alloy sheet having both high strength and bendability can be obtained. When the total reduction is less than 75%, the finally obtained tab has insufficient strength, and the tab may be bent in the middle of the opening. From the viewpoint of avoiding this problem, it is preferable to set the total reduction rate of cold rolling to 80% or more.
On the other hand, when the total reduction ratio exceeds 95%, problems such as reduction in Cube orientation density and excessive increase in strength of the aluminum alloy sheet may occur. As a result, the bending property of the tab may be deteriorated. From the viewpoint of avoiding this problem, it is preferable to set the total reduction rate of cold rolling to 90% or less.
After the cold rolling is finished, a coating treatment may be performed as necessary. The coating and firing temperature can be appropriately determined depending on the physical properties of the coating film. In general, if the firing temperature is in the range of 240 to 300 ℃, the bendability and strength of the resulting tab may be adversely affected.
[ examples ] A method for producing a compound
Examples of the above aluminum alloy sheet are explained below. The present invention is not limited to the embodiment, and can be modified as appropriate without departing from the spirit of the present invention.
In this example, first, ingots of aluminum alloys (alloys a to P) having the chemical compositions shown in table 1 were produced by the 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 thereby prepare a hot rolled sheet. Next, the hot-rolled sheet was cold-rolled under the conditions shown in Table 2 to produce aluminum alloy sheets (test materials 1 to 42) having a thickness of 0.33 mm. In the hot rough rolling, the rolling is performed in a plurality of passes by using a reversing mill. In addition, finish hot rolling is performed using a four stand tandem mill. In the cold rolling, a single rolling mill is used for 4 to 7 passes of rolling.
< evaluation of Hot rolled sheet >
A part of the hot-rolled sheet was collected during the production of each test material, and structure observation and texture analysis were performed.
Observation of tissue
The hot rolled sheet was ground by the Barker method, and the sheet section (L-ST plane) parallel to the rolling direction was observed. The results are shown in tables 3 and 4. In the column of "structure observation" in tables 3 and 4, the symbol a is described in the case of a completely recrystallized structure and the symbol B is described in the case of a rolled structure remaining as a result of the structure observation.
For example, as shown in fig. 1, the completely recrystallized structure is composed of a plurality of granular crystals. On the other hand, for example, as shown in fig. 2, the rolled structure is a fibrous structure stretched in the rolling direction. Note that the vertical direction in fig. 1 and 2 is the thickness direction (ST direction), and the horizontal direction is the rolling direction (L direction).
Analysis of texture
Cube orientation density of the above-described plate cross section (L-ST plane) subjected to the structure observation was calculated by the SEM-EBSD (scanning electron microscope-electron back scattering diffraction) method. Then, Cube orientation densities in all ranges from the center to the plate surface in the thickness direction were averaged. The average value is converted into a magnification ratio with respect to the Cube orientation density of a separately calculated random orientation sample, and is shown in the column of "Cube orientation density" in tables 3 and 4. The Cube orientation density was calculated from all crystal grains having a Cube orientation crystal plane index within 15 DEG from {001} < 100 > tilt angle. As the random orientation sample, aluminum powder having no texture was used. Texture was analyzed using oim (organization imaging microsepy) manufactured by TSL corporation.
< evaluation of test Material >
The test materials were evaluated for tensile properties, texture, bending properties of a tab, tab strength and formability.
Tensile Properties
Tensile test pieces of JIS5 were collected from each test material, and the coating film was removed. Thereafter, a tensile test was conducted in accordance with the provisions of JIS Z2241, and the 0.2% proof stress and elongation were evaluated. The test piece was collected so that the longitudinal direction was parallel to the rolling direction.
Texture
Cube orientation densities on the plate surface and the plate center plane in the thickness direction (ST direction) were measured by X-ray diffraction method. Then, the average value of the Cube orientation density of the plate surface and the Cube orientation density of the plate center surface was calculated. The average value is converted into a magnification ratio with respect to the Cube orientation density of a separately calculated random orientation sample, and is shown in the column of "Cube orientation density" in tables 3 and 4. The Cube orientation density was calculated from all crystal grains having a crystal plane index from Cube orientation, i.e., a distance {001} < 100 > inclination angle within 15 degrees, in the same manner as in the evaluation of hot-rolled sheets. Further, as the random orientation sample, an aluminum powder having no texture was used.
Formability
From each test material, a stay-on tab of the type of DRT was molded by using a die, and the presence or absence of occurrence of cracks during the processing was evaluated. The results are shown in tables 3 and 4. In the column "formability" in tables 3 and 4, the symbol a is described when no fracture occurs, and the symbol B is described when a fracture occurs.
Bendability of tab
After the stay tab 1 is formed in the same manner as described above, the tab 1 is attached to the rivet 21 of the can lid 2 as shown in fig. 3. After the tab 1 is pulled up by hand to normally open the notch portion 22, the tab 1 is bent until the tab 1 falls down on the side of the notch portion 22 opposite to the original position (see arrow 101). Thereafter, the tab 1 is bent back to its original position (see arrow 102). The pulling-up operation and the bending-back operation were repeated to evaluate whether the tab was torn or not. The results are shown in tables 3 and 4. In the column of "bendability" in tables 3 and 4, the symbol a is described when the tab 1 is not torn at the time of two reciprocations, and the symbol B is described when the tab 1 is torn at a lower reciprocation than two reciprocations.
Tab strength
After the tab 1 is attached to the rivet 21 of the can end 2 in the same manner as described above, the tab 1 is rotated by 90 ° about the rivet 21 (arrow 103) as shown in fig. 4, and a load is applied only to the tab 1 when the tab 1 is pulled up. In this state, the tab was pulled up by a can opener, and the load until the tab 1 was bent was measured. The results are shown in tables 3 and 4. In the column "tab strength" in tables 3 and 4, the symbol a is described when the load at the time of tab bending is 30N or more, and the symbol B is described when the load is less than 30N.
[ TABLE 1 ]
[ TABLE 2 ]
[ TABLE 3 ]
[ TABLE 4 ]
As shown in tables 1 to 3, the test materials 1 to 20 had chemical compositions and textures in the above-described specific ranges, and had tensile strengths and elongations in the above-described specific ranges. Therefore, these test materials can achieve both high strength and flexibility. The pull rings produced from these test materials were excellent in formability, bendability, and strength.
As shown in tables 1, 2, and 4, in the test materials 21 and 22, since the amount of Si or the amount of Fe is larger than the above-specified range, a large amount of intermetallic compounds are formed. As a result, these test materials had poor bending properties of the tab.
The test materials 23, 25, and 27 had lower tensile strength than the above-specified range because any of the Cu amount, Mn amount, or Mg amount was less than the above-specified range. Therefore, the pull tab of these test materials had low strength.
The test material 24 had a higher Cu content than the above-specified range, and therefore had a higher tensile strength than the above-specified range. Therefore, the test material 24 was inferior in the tab formability and bendability.
In the test material 26, the Mn content is larger than the specific range, and therefore the tensile strength is higher than the specific range. Therefore, the bending property of the tab of the test material 26 was poor.
Since the test material 28 contains Mg in an amount larger than the above-specified range, cracking occurred at the end of the sheet during hot rolling. Therefore, the production of the test material 28 was stopped without performing cold rolling.
The test material 29 had a lower tensile strength than the above-specified range because the Cr content was smaller than the above-specified range. Therefore, the pull tab of the test material 29 has low strength.
Since the test material 30 contains Cr in an amount larger than the above-specified range, the tensile strength is higher than the above-specified range. In addition, coarse intermetallic compounds are formed on the test material 30. Therefore, the bending property of the tab of the test material 30 was poor.
Since the homogenization temperature of the test material 31 is higher than the above-specified range, the surface is strongly oxidized, and the surface quality is lowered. Therefore, the production of the test material 31 was stopped without performing the steps after the hot rolling.
In the test material 32, since the average reduction ratio at the time of hot rough rolling is smaller than the above-described specific range, the number of passes in hot rough rolling increases, and the plate temperature at the time of completion of hot rough rolling is lower than the above-described specific range. As a result, cracks are generated at the plate end portions during the finish hot rolling. Therefore, the production of the test material 32 was stopped without performing cold rolling.
In the test material 33, the average reduction ratio in the hot rough rolling is larger than the above-specified range. As a result of the progress of recrystallization in the hot rolling, the Cube orientation density of the test material 33 was lower than the above-specified range. Therefore, the bending property of the tab of the test material 33 was poor.
In the test material 34, the plate temperature at the end of hot rough rolling was higher than the above-specified range. Thus, since recrystallization proceeds in the hot rolling, the Cube orientation density of the test material 34 is lower than the above-described specific range. As a result, the test material 34 was poor in the bending property of the tab.
The test material 35 has a smaller plate thickness at the end of hot rough rolling than the above-specified range, and therefore the reduction at the time of hot finish rolling is insufficient. As a result, the rolled structure remained on the hot-rolled sheet, and the Cube orientation density of the test material 35 was lower than the above-specified range. Therefore, the bending property of the tab of the test material 35 was poor.
Since the thickness of the test material 36 at the end of the hot rough rolling is larger than the above-specified range, the reduction amount at the time of the hot finish rolling is increased. As a result of the progress of recrystallization in the hot rolling, the Cube orientation density of the test material 36 was lower than the above-specified range. Therefore, the bending property of the tab of the test material 36 was poor.
In the test material 37, the strain rate of the first stand (first pass) of the hot finish rolling is smaller than the above-described specific range. As a result of the progress of recrystallization in the hot rolling, the Cube orientation density of the test material 37 was lower than the above-specified range. Therefore, the bending property of the tab of the test material 37 was poor.
The test material 38 has a large strain rate in the first stand after the hot finish rolling compared to the above-specified range, and therefore lubrication during rolling is insufficient. As a result, the surface of the plate becomes rough and the surface quality is deteriorated. Therefore, the production of the test material 38 was stopped without performing cold rolling.
In the test material 39, the temperature of the hot-rolled sheet was lower than the above-specified range, so that recrystallization could not be completed and the rolled structure remained on the hot-rolled sheet. As a result, the Cube orientation density of the test material 39 was lower than the above-specified range. Therefore, the bending property of the tab of the test material 39 was poor.
The temperature of the hot-rolled sheet in the test material 40 was higher than the above-specified range, and therefore the lubrication during rolling was insufficient. As a result, the surface of the plate becomes rough and the surface quality is deteriorated. Therefore, the production of the test material 40 was stopped without performing cold rolling.
In the test material 41, the total reduction ratio in the cold rolling is smaller than the above-specified range, and therefore the tensile strength is lower than the above-specified range. As a result, the strength of the tab of the test material 41 was low.
The test material 42 had a tensile strength higher than the above-described specific range because the total reduction ratio in the cold rolling was higher than the above-described specific range. As a result, the bending property of the tab of the test material 42 was poor.
Claims (5)
1. An aluminum alloy sheet for a tab, comprising:
a chemical composition comprising Si: 0.01 to 0.20 mass%, Fe: 0.01 to 0.35 mass%, Cu: 0.005-0.15 mass%, Mn: 0.005-0.50 mass%, Mg: 4.0 to 5.0 mass% and Cr: 0.005 to 0.15 mass%, the balance being Al and unavoidable impurities; and
texture, the Cube orientation density of which is 1.5 times or more of that of the randomly oriented sample in all the range from the center of the plate to the surface of the plate in the thickness direction,
0.2% proof stress is 280-360 MPa,
the elongation is 5% or more.
2. The aluminum alloy sheet for tab of claim 1, wherein,
the texture is provided, and the Cube orientation density is 2.0 times or more and 12.0 times or less of that of a randomly oriented sample in all ranges from the center of the plate to the surface of the plate in the thickness direction.
3. A method for manufacturing an aluminum alloy plate for a tab,
preparing an ingot having a chemical composition comprising Si: 0.01 to 0.20 mass%, Fe: 0.01 to 0.35 mass%, Cu: 0.005-0.15 mass%, Mn: 0.005-0.50 mass%, Mg: 4.0-5.0 mass%, Cr: 0.005 to 0.15 mass%, the balance being Al and unavoidable impurities,
heating the ingot at 450-540 ℃ for 1-24 hours to perform homogenization treatment,
the ingot is subjected to hot rough rolling in a plurality of passes so that the average reduction per pass from a plate thickness of less than 150mm to the end is 8 to 40%, the plate thickness at the end is 20 to 32mm, and the plate temperature at the end is 400 to 500 ℃,
then, a hot-rolled sheet having a texture in which the Cube orientation density is 8.0 times or more the randomly oriented sample over the entire range from the center to the surface of the sheet in the thickness direction is produced by performing a plurality of passes of hot finish rolling so that the strain rate of the first pass is 1 to 25/sec and the sheet temperature at the end is 310 to 390 ℃,
thereafter, the hot-rolled sheet is cold-rolled.
4. The method of manufacturing an aluminum alloy sheet for a tab according to claim 3,
the hot-rolled sheet is produced with the texture having a Cube orientation density 10 to 60 times that of a randomly oriented sample at all positions in the thickness direction from the center of the sheet to the surface of the sheet.
5. The method of manufacturing an aluminum alloy sheet for a tab according to claim 3 or 4,
the total reduction rate in the cold rolling is 75-95%.
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| JP2015192022A JP6667189B2 (en) | 2015-09-29 | 2015-09-29 | Aluminum alloy plate for tab and manufacturing method thereof |
| PCT/JP2016/078681 WO2017057491A1 (en) | 2015-09-29 | 2016-09-28 | Aluminum alloy plate for tabs, and method for producing same |
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| JP6640958B1 (en) * | 2018-11-15 | 2020-02-05 | 株式会社神戸製鋼所 | Aluminum alloy plate for magnetic disk, aluminum alloy blank for magnetic disk and aluminum alloy substrate for magnetic disk |
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| CN102974726A (en) * | 2012-11-30 | 2013-03-20 | 河南明泰铝业股份有限公司 | Rolling method of pop-top can pull-tab material |
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| US5469912A (en) * | 1993-02-22 | 1995-11-28 | Golden Aluminum Company | Process for producing aluminum alloy sheet product |
| JPH09268341A (en) * | 1996-04-01 | 1997-10-14 | Furukawa Electric Co Ltd:The | Baking-coated al alloy sheet for can lid material, excellent in stress corrosion cracking resistance in score part, and its production |
| JPH108176A (en) * | 1996-04-25 | 1998-01-13 | Nippon Light Metal Co Ltd | Aluminum alloy sheet low in proof stress and excellent in ultimate deformability and its production |
| JP2007277694A (en) * | 2006-04-12 | 2007-10-25 | Furukawa Sky Kk | Painted aluminum-alloy sheet for lid of positive pressure can, and manufacturing method therefor |
| JP5581254B2 (en) * | 2010-03-31 | 2014-08-27 | 株式会社神戸製鋼所 | Aluminum alloy plate for tab and manufacturing method thereof |
| CN103014452B (en) * | 2012-12-27 | 2015-03-18 | 亚洲铝业（中国）有限公司 | 5182 aluminum alloy tab stock substrate and production method thereof |
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| CN102974726A (en) * | 2012-11-30 | 2013-03-20 | 河南明泰铝业股份有限公司 | Rolling method of pop-top can pull-tab material |
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| Title |
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| Effect of Mn contents on ultimate deformation ability of 5182 alloy sheet by twin belt casting;Zhao Pizhi etal;《Proceeding of the 91th conference of the Japan institute of light metals》;19961031;137-138 * |
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