JP5670215B2 - Aluminum alloy plate for can body and manufacturing method thereof - Google Patents

Description

  The present invention provides an aluminum alloy plate for a can body, and more specifically, even when it is thin, high strength can be obtained, and even when it is formed into a can body by drawing or DI processing (drawing, ironing), and then subjected to paint baking or heat treatment. The present invention relates to an aluminum alloy plate for can bodies that can maintain high can body strength, and a method for producing the same.

  The can body of a beverage can made of an aluminum alloy plate is manufactured through a process of cup forming, DI processing, trimming, cleaning, drying, painting, baking, necking, and flange processing by applying oil to the plate material. Reduction of the weight of the can body is effective not only for reducing transportation costs but also for environmental conservation. For this purpose, it is necessary to reduce the thickness of the material. However, if the thickness of the can is simply reduced, the strength of the can body will decrease, so if the thin wall of the can is pressed against the projection during buckling of the can, transporting or handling the can, the can wall There arises a problem that a dent is formed on the surface, or that the tip of the protrusion pierces and penetrates the can wall portion and the content leaks.

  In order to solve the above problems, it is necessary to make the aluminum alloy plate for can bodies, which is a raw material, thinner than the conventional thickness of 0.3 mm and to increase the strength, and drawing processing or DI processing ( It is necessary to keep the strength of the can body high even when it is molded into a can body by drawing and ironing processing, and paint baking or heat treatment.

  Conventionally, as an aluminum alloy for a can body, an aluminum alloy in which strength is improved by adding Mg as a main alloy component to an Al—Mn based aluminum alloy has been proposed. The addition of Mg is due to the trend toward material integration that seeks to obtain can end materials represented by 5182 alloy, which requires pressure strength, and can body materials that require formability, with the same components from the viewpoint of recycling. Have been proposed, and aluminum alloys for can bodies having various Mg contents have been proposed (see Patent Documents 1 to 10).

  However, the above aluminum alloy is a JIS 3004 alloy (Al-1.0 to 1.5% Mn-0.8 to 1.3% Mg), which is a conventional aluminum alloy for can bodies having a Mg content of about 1%. 3104 alloy (Al-0.8 to 1.4% Mn-0.8 to 1.3% Mg) or AA3204 alloy (Al-0.8 to 1.5% Mn-0.8 to 1.5%) Although an improvement in strength is obtained as compared with Mg), satisfactory results are not obtained with respect to the compatibility of the moldability and can strength at the time of DI molding and drawing when the thickness is reduced.

  Also, in the distribution process of the can body, due to foreign matter coming into contact with or colliding with the can body part, or foreign matter being caught between the can body parts, a minute hole shape called pinhole on the can wall In order to solve this problem, an aluminum alloy plate for cans excellent in pinhole properties has been proposed (see Patent Document 11), and Aluminum alloy plates with increased piercing strength used for pinhole evaluation have also been proposed (see Patent Document 12), but these aluminum alloy plates are not necessarily sufficient as a material for cans.

JP 58-224145 A JP-A-61-261466 Japanese Patent Laid-Open No. 57-120648 Japanese Patent Laid-Open No. 5-112854 Japanese Patent Laid-Open No. 3-207840 JP-A-4-362151 JP 2000-309838 A JP 2000-309839 A Japanese Patent Laid-Open No. 2001-3130 JP 2001-32032 A JP 2007-197817 A JP 2006-77296 A

  The present invention has been made in order to eliminate the above-mentioned conventional problems in a can body aluminum alloy plate based on a 3000 series (Al-Mn series) aluminum alloy. An object of the present invention is to provide an aluminum alloy plate for a can body that has high strength, has high formability and has a predetermined can body strength, and a method for producing the same even when the thickness is .27 mm.

In order to achieve the above object, the aluminum alloy sheet for can bodies according to claim 1 has Mn: 1.1 to 1.3%, Mg: 1.2 to 1.5%, Cu: 0.15 to 0.00. 3%, Fe: 0.28 to 0.4%, Si: 0.1 to 0.3%, (Mn% / Fe%): 3.0 to 4.0, (Mg% / Mn%) )> 1.0, (Mn% + Mg% + Cu%): Cold rolling satisfying the relationship of 2.6 to 3.1 and having a sheet thickness of 0.23 to 0.27 mm consisting of the remaining aluminum and unavoidable impurities The 45% direction ear rate is 2.5 to 3.5%, (45 ° direction ear rate)> (0-180 ° direction ear rate). The yield strength after baking at 205 ° C. for 10 minutes is 280 to 320 MPa, and the difference in tensile strength and yield strength before and after baking is 15 MPa or more. It is characterized by being. In the following description, all alloy component values are indicated by mass%.

  An aluminum alloy plate for a can body according to claim 2 is characterized in that, in claim 1, a resin layer is coated before the cold-rolled plate is formed into a can body.

  A method for producing an aluminum alloy plate for a can body according to claim 3 is a method for producing an aluminum alloy plate for a can body according to claim 1, wherein the ingot of the aluminum alloy having the composition according to claim 1 is homogeneously produced. After the heat treatment, hot rolling comprising hot rough rolling and hot finish rolling is performed, and the hot rough rolling is performed in a hot rough rolling stand with a start temperature of 500 to 540 ° C. and an end temperature of 430 to 480 ° C. , Rolled to a thickness of 15 to 30 mm, the rolled material after the hot rough rolling was transferred to a hot finish rolling stand, and hot finish rolling was performed at an end temperature of 310 to 350 ° C., followed by cold Rolling is performed to obtain a sheet thickness of 0.23 to 0.27 mm.

  The method for producing an aluminum alloy sheet for a can body according to claim 4 is characterized in that in claim 3, intermediate annealing is performed prior to the cold rolling.

  According to the present invention, even when the plate thickness is reduced to 0.23 to 0.27 mm, high strength can be obtained. Even when the can body is formed by drawing or DI processing and then painted or baked or heat-treated, the can body Provided are an aluminum alloy plate for a can body that can maintain high strength and a method for producing the same.

In an Example, it is a figure which shows the bottom part of the can-like body used in order to measure bottom wrinkle maximum height, and in detail, the can-like body obtained by the redrawing process in the middle of DI processing of an aluminum alloy plate It is a figure which shows a bottom part.

The significance and reasons for limitation of the alloy components in the aluminum alloy sheet for can bodies of the present invention are as follows.
Mn additionally improves the strength of the molded can body, and further disperses the Al-Mn-Fe- (Si) intermetallic compound to prevent seizure on the mold during ironing. It functions to improve ironing processability. The preferred content is in the range of 1.1 to 1.3%. If the content is less than 1.1%, the effect of improving the strength cannot be obtained. If the content exceeds 1.3%, depending on the amount of Fe, Al ₆ (Mn , Fe) coarse crystallized products are generated, and breakage is likely to occur during ironing. In the case of a resin-coated plate, the resin is damaged by the coarse crystallized material, and the corrosion resistance of the can body is deteriorated, and the flange workability and cracking at the time of winding are likely to occur. Furthermore, since the Al—Mn—Si intermetallic compound increases and the amount increases, it becomes an undesirable propagation path for cracks during the piercing test. The Al—Mn—Si intermetallic compound is preferably 2 μm or less.

Mg functions to increase the strength of the molded can body, but if it exceeds 1.5%, it becomes difficult to control the ear rate, and oxidation of Mg is promoted during the homogenization process, resulting in a reduction in plate surface quality. To do.

  Cu, together with Mg, forms a solid solution or forms an Al-Mg-Cu compound to further improve the strength of the molded can body and to suppress softening due to heating such as paint baking To do. The preferred content is in the range of 0.15 to 0.3%, and if it is less than 0.15%, the effect of improving the strength cannot be obtained, and if it exceeds 0.3%, the work hardening becomes too large and the formability is too high. Deterioration such as lowering and corrosion resistance occurs.

Although Fe is inevitably contained as an impurity , in the present invention, since strength is imparted by Mn, when Fe exceeds 0.4%, a coarse Al ₆ (Mn, Fe) compound or Since the Al—Mn—Fe—Si intermetallic compound produced by transformation in the homogenization treatment is increased and the amount thereof is increased, the moldability and the piercing strength are lowered. The smaller the Al—Mn—Fe— (Si) -based intermetallic compound is preferable.

Si is inevitably contained as an impurity, and the preferred content is in the range of 0.1 to 0.3%. If it is less than 0.1%, the use of a metal having a purity of 99.9% or more in the production of the material increases, and it is not preferable from the viewpoint of recycling as a can body material using a large amount of recycled material. If it exceeds 0.3%, an Al—Mn—Si intermetallic compound or a coarse Mg ₂ Si intermetallic compound is produced, which hinders strength improvement. Moreover, it becomes a propagation path of the crack at the time of the piercing test, and hinders the piercing strength.

  The ratio of Mn content to Fe content (Mn% / Fe%) affects the formation of Al-Mn-Fe compounds, yield strength after baking, 45 ° ears and 0-180 ° direction It affects the balance of the ear, the pressure resistance after being formed into a can body, the piercing strength and the flange formability. In the present invention, a preferable range of (Mn% / Fe%) is 3.0 to 4.0.

  When (Mn% / Fe%) is less than 3.0, the yield strength after baking is less than 280 MPa, and the 0-180 ° ear is larger than the 45 ° ear, which induces wrinkles at the end of the cup during cupping. In addition, the can wall is easily cracked during DI molding, and the flange portion is easily cracked during flange molding. Further, the pressure resistance of the can body is less than 600 kPa, and the piercing strength tends to be less than 40N. When (Mn% / Fe%) exceeds 4.0, the yield strength after baking is likely to exceed 320 MPa. Due to insufficient ductility, neck formability is reduced, and the flange portion is easily cracked during flange molding. .

  The ratio of Mg content to Mn content (Mg% / Mn%) affects the strength difference before and after baking. In the present invention, the preferred range of (Mg% / Mn%) is a range exceeding 1.0. When the value of (Mg% / Mn%) exceeds 1.0, the generation of bottom wrinkles is suppressed by improving the uniform deformation performance by adding Mg, and the DI moldability is improved. Further, the strength of the base plate increases due to the improvement of work hardening ability by Mg, and the amount of recovery in subsequent baking is increased, so the difference in tensile strength and proof stress before and after baking tends to be 15 MPa or more, It has the effect of reducing wrinkles during drawing and improving flange formability. When (Mg% / Mn%) is 1.0 or less, bottom wrinkles are likely to occur, and the difference in tensile strength and proof stress before and after baking is likely to be less than 15 MPa. It becomes easy and a flange part becomes easy to break at the time of flange molding.

  The total of Mn content, Mg content and Cu content, (Mn% + Mg% + Cu%), affects the yield strength after baking or the strength difference before and after baking. In the present invention, the preferable range of (Mn% + Mg% + Cu%) is 2.6 to 3.1. When (Mn% + Mg% + Cu%) is less than 2.6, the yield strength after baking is less than 280 MPa. The pressure resistance and piercing strength after forming into a can body are insufficient. If it exceeds 3.1, the yield strength after baking is likely to exceed 320 MPa, and the flange portion is liable to break during flange molding due to insufficient ductility.

  In the aluminum alloy plate of the present invention, the ear rate in the 45 ° direction is 2.5 to 3.5%, and the relationship is (the ear rate in the 45 ° direction)> (the ear rate in the 0-180 ° direction). This is very important. If the ear rate in the 45 ° direction is less than 2.5%, the ear rate of 0 to 180 ° is relatively large, which is not preferable. If the ear rate in the 45 ° direction exceeds 3.5%, the ear height will be caught by transport after cup molding or DI processing, and the variation in ear height after DI processing will not be removed by subsequent trimming. The flange width, which is important for tightening, is reduced. In the relationship of (the ear rate in the 45 ° direction) ≦ (the ear rate in the 0-180 ° direction), since the two places are pulled strongly at the end of the cup molding, the ears are torn and lead to cracks in the DI processing. Since there are four directions at 45 °, it is supported at four points, and ear tears are unlikely to occur.

  Moreover, in the aluminum alloy plate of the present invention, it is desirable that the proof stress is 280 to 320 MPa after air baking at 205 ° C. for 10 minutes, and the difference in tensile strength and proof strength before and after baking. Is important to be 15 MPa or more. As described above, the aluminum alloy plate according to the present invention is characterized by high proof stress after baking, so care must be taken to maintain neck formability and flange formability. If any of the difference between the tensile strength and the proof stress before and after the baking is less than 15 MPa, the can wall portion does not recover, so that it tends to buckle during neck molding (drawing), and flange cracking easily occurs.

  As described above, the can body is formed by forming a cylindrical container with a bottom by drawing or DI, and trimming, necking, or flanging the opening. The DI processing includes a step of punching a plate into a disc, a step of drawing the disc into a cup, a step of redrawing the cup into a can-like body, and a step of ironing the side wall of the can-like body.

  The paint baking process is usually performed under the condition of heating at a temperature of 200 to 220 ° C. for about 5 to 20 minutes after the trimming process of can body molding. In the case of using a conventional aluminum alloy plate that is not coated with a resin before molding the can body, the outer surface of the can is printed and then the resin is coated on the inner surface of the can for corrosion resistance from the contents and external factors. When the resin coating is applied, only the outer surface printing is performed when the resin coating is on both sides, and the opposite surface (can outer surface) is printed when the resin coating is one side of the inner surface of the can.

Below, the manufacturing method of the aluminum alloy plate of this invention is demonstrated below.
An aluminum alloy having the above composition is ingoted by DC casting, and the resulting ingot is homogenized and hot rolled. The homogenization treatment is desirably performed at a temperature of 580 to 620 ° C. for 2 to 10 hours. The hot rolling includes hot rough rolling that is reverse-rolled in a hot rough rolling stand, and hot finish rolling that is performed in a hot finish rolling stand that includes a plurality of tandem rolling mills. It is preferable that the hot rough rolling start temperature is 500 to 540 ° C., the hot rough rolling finish plate thickness is 15 to 30 mm, and the hot rough rolling finish temperature is 430 to 480 ° C. The rolled material after the hot rough rolling is transferred to a hot finish rolling stand and subjected to hot finish rolling with an end temperature of 310 to 350 ° C., and a thickness of 1.7 to 2.5 mm. Thereafter, cold rolling is performed to a thickness of 0.23 to 0.27 m. If necessary, intermediate annealing may be performed prior to cold rolling, and final heat treatment may be performed after cold rolling.

  When the resin layer is coated prior to forming the aluminum alloy plate of the present invention on the can body, the aluminum alloy plate is degreased by alkali or acid cleaning, phosphoric acid chromate treatment, or Zr, Ti, Mn, V series treatment. After performing chemical conversion treatment (primary treatment), etc., a polyester-based, polyolefin-based, or polyamide-based resin is coated on both sides or one side of the plate. As a coating method, there are a method of laminating a resin made into a film on the surface of an aluminum alloy plate by heat fusion, a method of directly coating a resin by melting it, and the like. In coating the resin, the aluminum alloy plate is heated to 200 to 300 ° C. These series of treatments may be carried out with a cut plate or continuously using a coil material.

The reasons for setting the manufacturing conditions are as follows.
When the homogenization treatment temperature is less than 580 ° C. and the homogenization treatment time is less than 2 hours, the infiltration of Al ₆ (Mn, Fe) and Mg ₂ Si, which are the grain boundary crystallization products of the ingot, is insufficient and fine. Since an Al—Mn—Si based compound remains, recrystallization failure tends to occur at the end of hot rolling, which causes an increase in 45 ° ear rate after cold rolling. When the homogenization temperature exceeds 620 ° C., eutectic melting occurs in a part of the ingot, and the surface quality of the plate surface tends to deteriorate. Even if the homogenization treatment is performed for more than 10 hours, no further effect is obtained and it is not economical, so the homogenization treatment time is preferably 10 hours or less.

  If the start temperature of hot rough rolling is less than 500 ° C., precipitation of the Al—Mn—Si compound is promoted, so that the amount of Mn solid solution decreases and the desired strength cannot be obtained. If the temperature exceeds 540 ° C., strength can be obtained, but since Mg is added in a large amount, the oxidation of Mg is promoted and the plate surface quality is deteriorated. When the end temperature of the hot rough rolling is less than 430 ° C., it is necessary to increase the reduction rate and the rolling speed in order to achieve the end temperature of the hot finish rolling, resulting in deterioration of the plate surface quality and plate distortion. Moreover, the end temperature of hot finish rolling becomes low, and recrystallization becomes insufficient. If the temperature exceeds 480 ° C., strain energy as a driving force for recrystallization cannot be accumulated in hot finish rolling, so that a sufficient recrystallized structure cannot be obtained after hot finish rolling. Will increase.

  If the plate thickness after hot rough rolling is less than 15 mm, strain energy as a driving force for recrystallization cannot be accumulated in hot finish rolling, and a sufficient recrystallized structure cannot be obtained after hot finish rolling. If the plate thickness after hot rough rolling exceeds 30 mm, the reduction ratio in hot finish rolling will increase, leading to deterioration of plate surface quality and plate distortion.

  When the finish temperature of hot finish rolling is less than 310 ° C., a sufficient recrystallized structure cannot be obtained after hot finish rolling, so the 45 ° direction ear rate increases. When the finish temperature of hot finish rolling exceeds 350 ° C., recrystallization is promoted, the 0 to 180 ° direction ear ratio of the final product plate increases, and the plate surface quality is liable to deteriorate.

  If the plate thickness after hot finish rolling is less than 1.7 mm, the strength will be insufficient due to a decrease in the cold rolling rate, and if the plate thickness after hot finish rolling exceeds 2.5 mm, the cold rolling rate will increase. Thus, the 45 ° ear rate after cold rolling increases.

  The final rising temperature of the cold rolling is preferably 170 ° C. or lower. Since Mg and Mn are added to the aluminum alloy sheet of the present invention, the temperature of the cold-rolled sheet is likely to rise due to processing heat generated during cold rolling. The strength is not obtained. From the viewpoint of productivity, it is desirable that the final rising temperature of cold rolling is 130 ° C. or higher.

  In the intermediate annealing prior to cold rolling, recrystallization may be partially insufficient depending on the alloy composition when the rising temperature of hot finish rolling is a relatively low temperature of 310 to 320 ° C. In this case, the 45 ° ears after cold rolling tend to be large, so in order to obtain a more stable material, heating or continuous annealing in a box annealing furnace for 1 to 10 hours in a temperature range of 350 to 450 ° C. You may heat within 10 minutes with a furnace.

  Hereinafter, examples of the present invention will be described in comparison with comparative examples to prove the effects. In addition, these Examples show one embodiment of this invention, and this invention is not limited to these.

Example 1 and Comparative Example 1
An aluminum alloy having the composition shown in Table 1 is ingoted by DC casting, and the obtained ingot is homogenized according to a conventional method, and then hot roughing is performed at a temperature of 530 ° C. in a hot roughing stand. The hot rough rolling was completed at a temperature of 460 ° C., and the plate thickness was 20 mm. The rolled material that has been subjected to hot rough rolling is transferred to a hot finish rolling stand, subjected to hot finish rolling at an end temperature of 320 ° C., and then cold rolled to obtain a thickness of 0.23 to 0.23. A 0.27 mm cold rolled plate was used. In Table 1, those outside the conditions of the present invention are underlined.

  Using the obtained cold rolled sheet as a test material, a tensile test was performed to measure the tensile strength (σB), proof stress (σ0.2), and elongation (δ) of the cold rolled sheet (base plate). The cold-rolled sheet is baked at 205 ° C. for 10 minutes, and the tensile strength (σB), proof stress (σ0.2), and elongation (δ) after baking are measured. And the difference in tensile strength and yield strength after baking. Furthermore, the ear rate in the 45 ° direction and the ear rate in the 90 ° direction (0-180 ° direction) were measured. The results are shown in Table 2. In Table 2, those outside the conditions of the present invention are underlined.

  The obtained cold-rolled plate was partly resin-coated on one side (can outer surface side) by the following method, and then formed into a can body by DI processing. The rest was molded into a can body by DI processing without performing resin coating.

  In forming the can body, the can body wall thickness was set to 0.100 mm in terms of aluminum thickness, and the can bottom grounding diameter was set to 48 mm. For those with resin coating, heat treatment was carried out at 200 ° C. for 30 seconds in order to increase the adhesion of the resin. For those without resin coating, the inner and outer surfaces were painted and baked at 205 ° C. for 10 minutes. Heat treatment was applied.

For resin coating, cold-rolled plates were washed with alkali, then subjected to chemical conversion treatment of phosphoric acid chromate (Cr deposition amount 20 mg / m ² ), and then heated with a heat roll in which a polyester resin film having a thickness of 15 μm was heated to 200 ° C. Lamination was performed only on one side of the plate by heat sealing. Further, after being kept at 270 ° C. for 30 seconds, it was cooled with water.

  The cold-rolled plate (test material) is molded into a can body, the can body after being subjected to the heat treatment equivalent to paint baking (test can), and the can body is molded from a previously resin-coated plate, and the heat treatment described above About the can (test can) which performed this, the pressure resistance, the piercing strength, and the bottom wrinkle height were measured by the following methods to evaluate the flange formability. The results are shown in Table 3.

Pressure resistance: The can bottom pressure resistance of the molded can body is measured, and 600 kPa or more is accepted.
Puncture strength: The resin film was removed from the molded can body to see the characteristics of the aluminum alloy itself that makes up the can body, and the neck of the can body (can body) was cut off to facilitate measurement. Then, attach the can body to the measuring device and measure the maximum load when a needle with a diameter of 1 mm and a tip of R0.5 mm is pierced into the can wall at a speed of 50 mm / min with an internal pressure of 196 kPa. did. The average value was determined with n = 10. The unit is N. Accept 40N or more. In addition, since the coating body etc. are attached to the can body of the aluminum alloy can marketed now, the piercing strength increases 10N on average compared with when there is no coating film etc.

  Maximum height of bottom wrinkle: Cold rolled plate (test material) Using a can-like body obtained in the process of redrawing the cup in the middle of the DI processing step into a can-like body, as shown in FIG. The wrinkle 12 was measured using a roundness meter (model EC-1010A) 2 manufactured by Mitutoyo, and a maximum wrinkle height measurement chart was obtained. This chart is a circular coordinate centered on the point O, and has an angle in the circumferential direction and an unevenness of the chime portion in the radial direction. In the obtained chart, for the adjacent peaks and valleys, the value obtained by subtracting (the value of the radius of the circumscribed circle of the peaks) from the value of the radius of the circumscribed circle of the peak is the wrinkle height, and one can The maximum wrinkle height distribution among the wrinkle height distributions on the entire circumference of the body 1 was defined as the maximum wrinkle height H. Moreover, the average value of the maximum wrinkle height H of five can-like bodies was computed, and it was set as the maximum bottom wrinkle height of the test material. The bottom wrinkle maximum height of 750 μm or less is regarded as acceptable.

  Flange formability: 100 cans are made from cold-rolled sheets (test material), necked up to 204 diameters, further flanged with a flange width of 2.2 mm, and visually observed for appearance of flange end cracks. It was evaluated by. In Table 3, all cans (100 cans) in which flange cracks did not occur were accepted (◯), and even one can with flange cracks was rejected (x).

  As shown in Table 2, all of the test materials 1 to 3 according to the present invention have high strength and an appropriate ear rate, and the test cans 1 to 3 formed from the test materials 1 to 3 are all pressure resistant. The piercing strength, bottom wrinkle maximum height and flange formability were good.

  On the other hand, since the test material 4 has a small amount of Mn (Mn% + Mg% + Cu%), and the proof stress after empty baking is low, the test can 4 molded from the test material 4 has a pressure resistance. Was low and the puncture strength was low. Since the test material 5 has a large amount of Mn and Fe, a large amount of crystallized matter increases, and the test can 5 formed from the test material 5 has poor piercing strength and flange formability. Moreover, since the test material 5 has a low (Mn% / Fe%), the ear ratio is poorly balanced.

  Since the test material 6 has a small amount of Mg, the value of (Mn% + Mg% + Cu%) is small, the yield strength after baking is low, and the test can 6 formed from the test material 6 has a low pressure resistance and a piercing strength. Was also low. Since the test material 7 has a large amount of Mg, the value of (Mn% + Mg% + Cu%) is large, and (Mn% / Fe%) is also high, so the yield strength after baking is too high and the elongation is low. The test can 7 molded from the material 7 was inferior in flange formability and caused bottom wrinkles.

  Since the test material 8 has a small amount of Cu, the value of (Mn% + Mg% + Cu%) is small, and since the amount of Si is also large, the yield strength after baking is low, and the test can 8 formed from the test material 8 is The pressure resistance was low and the puncture strength was low. Since the test material 9 has a large amount of Cu, the value of (Mn% + Mg% + Cu%) becomes large, the proof stress after baking is too high, and the test can 9 formed from the test material 9 has poor flange formability. It became a thing. Moreover, since the test material 9 has a high (Mn% / Fe%), the balance of the ear rate is poor.

1 Canned body obtained by redrawing in the middle of DI processing process 2 Roundness meter 11 Chime part 12 Wrinkle

Claims (4)

Mn: 1.1 to 1.3% (mass%, the same applies hereinafter), Mg: 1.2 to 1.5%, Cu: 0.15 to 0.3%, Fe: 0.28 to 0.4% , Si: 0.1 to 0.3%, (Mn% / Fe%): 3.0 to 4.0, (Mg% / Mn%)> 1.0, (Mn% + Mg% + Cu%) ): A cold rolled plate satisfying the relationship of 2.6 to 3.1 and having a thickness of 0.23 to 0.27 mm consisting of the balance aluminum and inevitable impurities, and about 45 ° The ear ratio in the direction is 2.5 to 3.5%, (the ear ratio in the 45 ° direction)> (the ear ratio in the 0-180 ° direction), and baked at 205 ° C. for 10 minutes. An aluminum alloy plate for a can body, characterized in that the later yield strength is 280 to 320 MPa, and the difference in tensile strength and yield strength before and after baking is 15 MPa or more. The aluminum alloy plate for a can body according to claim 1, wherein a resin layer is coated before the cold rolled plate is formed into a can body. The ingot of the aluminum alloy having the composition according to claim 1 is subjected to hot rolling including hot rough rolling and hot finish rolling after homogenization, and the hot rough rolling is performed in a hot rough rolling stand. The starting temperature is 500 to 540 ° C., the end temperature is 430 to 480 ° C., the sheet is rolled to a thickness of 15 to 30 mm, the rolled material after hot rough rolling is transferred to a hot finish rolling stand, and the end temperature is 310 The method for producing an aluminum alloy sheet for a can body according to claim 1, wherein hot finish rolling is performed to ˜350 ° C. and then cold rolling is performed to obtain a sheet thickness of 0.23 to 0.27 mm. . The method for producing an aluminum alloy sheet for a can body according to claim 3, wherein intermediate annealing is performed prior to the cold rolling.

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