JP2014084473A - Aluminum alloy sheet for can body and production method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an aluminum alloy sheet for a can body, excellent in formability and treatability of homogenization treatment, and to provide a production method of the aluminum alloy sheet for the can body, and aluminum alloy material for the can body capable of providing the aluminum alloy sheet for the can body.SOLUTION: Aluminum alloy material having a composition containing, by mass%, Si:0.40% or less, Fe:0.30 to 0.60%, Cu:0.10 to 0.50%, Mn:0.80 to 1.20%, Mg:0.50 to 1.70%, Zn:0.30% or less, Ti:0.15% or less and the balance Al with inevitable impurities is subjected to homogenization treatment under conditions of a retention temperature of 565±10°C and retention time of 4 to 10 hours.

Description

  The present invention relates to an aluminum alloy plate for a can body used for a can body such as a beverage can and a method for producing the same.

In slab casting of an aluminum alloy material, a heat treatment called a homogenization treatment (HOMO treatment) is performed for the purpose of homogenizing microsegregation, precipitation / growth of a supersaturated solid solution, phase transformation of a metastable phase, and the like.
The said homogenization process is generally performed also about the aluminum alloy material for can bodies used for can bodies, such as a drink can (for example, refer patent documents 1-3).

In the case of an aluminum alloy material for can bodies, the Al ₆ (Fe, Mn) phase, which is a crystallized product produced during casting, is transformed into a hard α-Al ₁₂ (Fe, Mn) ₃ Si phase by homogenization treatment. It is known that if the process does not proceed sufficiently, problems such as galling and running out of the body occur during canning by DI (Drawing and Ironing) processing, for example.

JP-A-8-60283 JP-A-1-96346 JP 2000-248326 A

  However, conventional aluminum alloy materials for can bodies are required to further improve the formability during DI processing. In addition, the homogenization treatment is required to be improved with high productivity and low energy consumption.

  The present invention has been made against the background of the above circumstances, and an object thereof is to provide an aluminum alloy plate for a can body that is excellent in formability and excellent in homogenization, and a method for producing the same.

  That is, the aluminum alloy plate for a can body of the present invention is, in mass%, Si: 0.40% or less, Fe: 0.30 to 0.60%, Cu: 0.10 to 0.50%, Mn: 0 .80 to 1.20%, Mg: 0.50 to 1.70%, Zn: 0.30% or less, Ti: 0.15% or less, with the balance being Al and inevitable impurities And the pregelatinization rate is 89% or more.

  The invention of the method for producing an aluminum alloy plate for a can body according to the present invention comprises subjecting the aluminum alloy material having the above composition to a homogenization treatment under conditions of a holding temperature of 565 ± 10 ° C. and a holding time of 4 to 10 hours. Features.

  In another embodiment of the method for producing an aluminum alloy sheet for a can body according to the present invention, the aluminum alloy material having the composition described above is homogenized a plurality of times under conditions of a holding temperature of 565 ° C. ± 10 ° C. and a holding time of 2 hours or more. It is characterized by processing.

  The total holding time of the plurality of homogenization treatments is preferably 4 to 10 hours.

  In addition, after the homogenization treatment is completed, hot rolling and cold rolling can be performed, and one or more intermediate annealings can be performed after the hot rolling or during the cold rolling.

Below, conditions, such as a composition prescribed | regulated to this invention, are demonstrated.
First, constituent parts of the aluminum alloy material for the can body and the alloy plate will be described. In addition, all content of each component demonstrated below is shown by the mass%.

Si: 0.40% or less Si forms a compound with Mg contained at the same time, and in addition to effecting solid solution hardening, precipitation hardening, and dispersion hardening, it forms an intermetallic compound with Al, Mn, Fe, etc. Demonstrates the effect of preventing seizure on the die during ironing. If the Si content exceeds 0.40%, it becomes brittle and the workability deteriorates, so the Si content is set to 0.40% or less. For the same reason, the upper limit of Si content is preferably 0.35%. If the Si content is less than 0.20%, it is not possible to obtain a sufficient anti-baking effect on the die during ironing, so the lower limit of the Si content is preferably 0.20%.

Fe: 0.30 to 0.60%
Fe exhibits the effect of refining the crystal and the effect of preventing seizure on the die during the ironing process. If the Fe content is less than 0.30%, the desired effect cannot be obtained. On the other hand, if the Fe content exceeds 0.60%, it becomes brittle and the workability deteriorates. For this reason, the Fe content is set to 0.30 to 0.60%.

Cu: 0.10 to 0.50%
Cu forms an intermetallic compound with Mg, and has solid solution hardening, precipitation hardening, and dispersion hardening actions. If the Cu content is less than 0.10%, these effects are poor, and if the Cu content exceeds 0.50%, the workability deteriorates. For this reason, Cu content shall be 0.10 to 0.50%.

Mn: 0.80 to 1.20%
Mn forms an intermetallic compound together with Fe, Si, and Al, becomes a crystallization phase and a dispersed phase, exhibits a dispersion hardening action, and exhibits an effect of preventing seizure to a die during ironing processing. If the Mn content is less than 0.80%, desired curing characteristics cannot be obtained. On the other hand, if the Mn content exceeds 1.20%, it becomes brittle and the workability deteriorates. For this reason, the Mn content is set to 0.80 to 1.20%.

Mg: 0.50 to 1.70%
Mg has a solid solution strengthening action, improves work hardening at the time of rolling, and exhibits dispersion hardening and precipitation hardening action by coexisting with the Si and Cu. If the Mg content is less than 0.50%, these functions and effects are not sufficiently exhibited, and if the Mg content exceeds 1.70%, the workability deteriorates, particularly the curl workability deteriorates. For this reason, the Mg content is set to 0.50 to 1.70%.

Zn and Ti Zn: 0.30% or less, Ti: 0.15% or less Zn has the effect of refining the intermetallic compounds of Mg, Si and Cu to be precipitated, but is used as a raw material when it contains Zn Aluminum cans and recycled materials can be used effectively. If the Zn content exceeds 0.30%, workability and corrosion resistance deteriorate, so the Zn content is set to 0.30% or less. Note that if the Zn content is less than 0.05%, the above-described effects cannot be obtained sufficiently, so the lower limit of the Zn content is preferably 0.05%.
Ti exerts the effect of refining crystal grains and improving workability. If the Ti content exceeds 0.15%, a coarse intermetallic compound is formed, so that the workability deteriorates and the toughness is lowered to easily generate pinholes. Therefore, the Ti content is 0.15%. The following. In addition, since the effect mentioned above is not fully acquired if Ti content is less than 0.03%, it is preferable to make the minimum of Ti content into 0.03%.
Further, other elements may be contained as 0.05% or less as impurities.

As described above, in the aluminum alloy plate for can bodies, the Al ₆ (Fe, Mn) phase, which is a crystallized product generated during casting, is transformed into a hard α-Al ₁₂ (Fe, Mn) ₃ Si phase by homogenization. Good formability can be obtained by sufficiently proceeding transformation into alpha. If the alpha conversion has not progressed sufficiently, problems such as galling and running out of the body will occur during can manufacturing by DI processing. For this reason, it is necessary to set the α conversion ratio indicating the degree of phase transformation of the Al ₆ (Fe, Mn) phase, which is an intermetallic compound, to the α-Al ₁₂ (Fe, Mn) ₃ Si phase to a predetermined value or more. is there.

The said alpha conversion rate is computable by following formula (1) using the peak intensity measured by the powder X-ray diffraction method. In addition, each peak intensity in following formula (1) uses the diffraction intensity (count number) of the peak of each phase from the diffraction X-rays satisfying the Bragg diffraction condition.
α rate (%) = (peak intensity of Al (Fe, Mn) Si) / (peak intensity of Al (Fe, Mn) Si + peak intensity of Al (Fe, Mn)) × 100 (1)

  The aluminum alloy plate for a can body of the present invention has an alpha ratio of 89% or more calculated by the above formula (1). Thus, since it has a sufficiently high α conversion rate, the aluminum alloy plate for can bodies of the present invention can suppress the occurrence of problems such as galling and torso cut when making cans by DI processing, It has excellent formability during DI processing.

Homogenization treatment: 565 ± 10 ° C. × 4 to 10 hours In the present invention, the alpha conversion rate is effectively increased by subjecting the aluminum alloy material having the above composition to a homogenization treatment. There is a temperature range suitable for causing the transformation of the Al ₆ (Fe, Mn) intermetallic compound into the α-Al ₁₂ (Fe, Mn) ₃ Si phase, and the temperature is too high or too low. However, the α transformation is insufficient. In addition, if the homogenization temperature exceeds 575 ° C, there is a risk of bulging internal defects due to hydrogen gas absorption. In this case, part of the surface of the can after DI can peel off and the appearance It becomes a defect. From the above, the temperature of the homogenization treatment needs to be 555 to 575 ° C. In addition, when the homogenization time is less than 4 hours, the α-ization does not proceed sufficiently and a defect occurs in the DI moldability. On the other hand, when the time for the homogenization treatment exceeds 10 hours, productivity is hindered and energy consumption increases.

In the present invention, the homogenization treatment may be performed multiple times. The homogenized aluminum alloy material is stored as it is, and is further homogenized after a certain time. The treatment can be carried out and it is not necessary to carry out the homogenization treatment several times in succession.
In the homogenization process multiple times, the holding time is set to a condition of 2 hours or more each time.
When the homogenization process is performed multiple times, fine precipitates that contribute to the baking hard characteristics required for baking coating, which are necessary as aluminum alloy materials for can bodies, are generated in the cooling process after the homogenization process previously performed. However, this is canceled by re-dissolution in the subsequent homogenization process. At this time, if the holding time of the subsequent homogenization treatment is shorter than 2 hours, re-dissolution is insufficient, and thus the holding time for each time needs to be 2 hours or more.
Moreover, also when performing a homogenization process in multiple times, holding temperature shall be 555-575 degreeC. Moreover, it is desirable that the total holding time of a plurality of homogenization processes is 4 to 10 hours. These reasons are as described above for the homogenization treatment: 565 ± 10 ° C. × 4 to 10 hours.

  The aluminum alloy material for can bodies of the present invention is, by mass%, Si: 0.40% or less, Fe: 0.30-0.60%, Cu: 0.10-0.50%, Mn: 0.80 -1.20%, Mg: 0.50-1.70%, Zn: 0.30% or less, Ti: 0.15% or less, the balance is composed of Al and inevitable impurities, Since it has a high alpha conversion rate, it is excellent in moldability.

  Moreover, one form of the manufacturing method of the aluminum alloy plate for can bodies of this invention is homogeneous to the aluminum alloy material which has the aluminum alloy composition of the said invention on the conditions of holding temperature 565 +/- 10 degreeC and holding time 4-10 hours. Since the heat treatment is performed, the processability of the homogenization treatment is excellent and the α conversion rate can be effectively increased.

It is a graph which shows typically an example of the relationship between the retention time of a homogenization process, and the grade of gelatinization. It is a figure which shows the image which mapped Si by the surface analysis by an electron beam microanalyzer (EPMA) about the alloy plate which has not performed the homogenization process, and the alloy plate from which the holding time of a homogenization process differs.

The aluminum alloy plate of the present invention can be produced by the following method.
The aluminum alloy having the composition of the present invention is usually made into a plate material through the steps of melting, casting, homogenizing treatment, hot rolling, cold rolling, intermediate annealing, and final cold rolling. Intermediate annealing can be performed one or more times after hot rolling or during cold rolling. In order to further increase the strength, an aging treatment can be performed after the final cold rolling. It is also possible to perform soaking between the homogenization treatment and hot rolling.

The homogenization treatment is performed under the conditions of a holding temperature of 565 ± 10 ° C. and a holding time of 4 to 10 hours.
FIG. 1 is a graph schematically showing an example of the relationship between the retention time of the homogenization process and the pregelatinization rate (degree of pregelatinization) calculated by the above equation (1). As shown in the drawing, the degree of alpha is increased while drawing an upward convex curve as the holding time is increased, and is saturated at the maximum value indicating that the alpha is completed.

  Moreover, FIG. 2 shows the image which mapped Si by the surface analysis by an electron beam microanalyzer (EPMA) about the hot rolled sheet which has not performed the homogenization process, and the hot rolled sheet from which the holding time of the homogenization process differs. FIG. The composition of these hot rolled sheets is as follows: Si: 0.30%, Fe: 0.45%, Cu: 0.40%, Mn: 1.00%, Mg: 1.25%, Zn: 0.10% , Ti: 0.05%, with the balance being Al and inevitable impurities.

2A is a composition image obtained for an alloy plate that has not been homogenized, and FIGS. 2B to 2G are holding times of 2 hours, 4 hours, and 5 hours, respectively. , 6 hours, 7 hours, and 8 hours. The left images in FIGS. 2A and 2B are SEM composition images, and the right images in FIGS. 2A and 2B show the Si detection density in the same field of view. It is a surface analysis mapping image shown. Moreover, the images of FIG. 2C to FIG. 2G are surface analysis mapping images each showing the Si detection concentration. From each figure, it can be seen that as the retention time increases, the amount of Si, which is an element contained in the α-Al ₁₂ (Fe, Mn) ₃ Si phase, increases, and α-ization proceeds.

  Moreover, the above homogenization process can also be implemented in multiple times. In this case, the holding temperature of each time is 565 ° C. ± 10 ° C., and the holding time is 2 hours or more. In addition, it is desirable that the total holding time of a plurality of homogenization processes is 4 to 10 hours.

  The conditions of each process of said hot rolling, cold rolling, intermediate annealing, and final cold rolling are not specifically limited, It can carry out on the conditions of a conventional method. The intermediate annealing can be performed once or more after hot rolling or during cold rolling. It is also possible to perform an aging treatment after the final cold rolling.

The aluminum alloy plate for can bodies of the present invention obtained as described above has a plate thickness of, for example, 0.210 to 0.470 mm, and a proof stress after paint baking of 230 to 320 N / mm ² .
The aluminum alloy plate for a can body of the present invention is used after being formed into a can body such as a beverage can by DI processing or the like. In this case, excellent moldability is exhibited.

Examples of the present invention will be described below.
An aluminum alloy ingot was obtained by melt casting an aluminum alloy with the composition shown in Table 1 (the balance being Al and inevitable impurities). Next, the obtained ingot was subjected to homogenization treatment, hot rolling, cold rolling, intermediate annealing and final cold rolling by the method for producing an aluminum alloy plate of the above embodiment, and the plate thickness was 0. A 30 mm aluminum alloy plate of each specimen was obtained. The conditions for each step are as shown in Table 2. Sample No. The retention time of 0 hours for the homogenization process in comparison G means that the cooling has been quickly performed after reaching the target temperature.

(mechanical nature)
The alloy No. Sample Nos. 1 and 2 were used. About the aluminum alloy plates of B to E and Comparative G, a JIS No. 5 test piece was prepared and subjected to a tensile test to examine mechanical properties. The tensile test method was performed according to JIS Z 2241, and the tensile test after baking was performed after heating at 210 ° C. for 10 minutes. The results are shown in Table 3, in which no clear difference is observed in the mechanical properties.

(Alpha conversion rate)
The alloy No. Sample No. 1 using No. 1 With respect to the aluminum alloy plates of A to C, E, Comparative F, Comparative G, and Comparative H, the alpha ratio (%) was determined by the formula (1) using a powder X-ray diffraction method. The results are shown in Table 4. Sample No. The homogenization treatment of Comparative F without the homogenization treatment at 565 ° C. × 0 hour of Comparative G is insufficient as the α conversion rate is less than 89%. By performing the homogenization treatment of A at 565 ° C. for 4 hours or more, an α conversion rate of 89% or more is obtained.

(DI moldability)
The alloy No. Sample No. 1 using No. 1 The aluminum alloy plates A, C, and Comparative G were canned by DI processing. At that time, the number of cans in which the barrel breakage occurred, and the barrel breakage ratio, which is the ratio of the number of cans in which the barrel breakage occurred to the number of cans produced, are as shown in Table 5. The DI processing conditions were such that the die clearance was adjusted and the third stage ironing conditions were made strict so that a cylinder cut was likely to occur. It can be seen that when the holding time of the homogenization treatment is 0 hour, the occurrence rate of torso is high, but when the holding time is 4 hours or more, there is no difference in the insufficiency rate.

(Peeling defect on DI can surface)
In addition, the alloy No. Sample No. 1 using No. 1 About the aluminum alloy plate of C and the comparison I, the can by DI process was performed and the visual inspection was performed about the presence or absence of the exfoliation defect of the surface. The results are as shown in Table 6, and when the holding temperature of the homogenization treatment is 565 ° C., there is no generation for 1,200 cans, but at 590 ° C. for 1,200 cans. The occurrence of 47 cans was observed.

Claims (5)

  In mass%, Si: 0.40% or less, Fe: 0.30 to 0.60%, Cu: 0.10 to 0.50%, Mn: 0.80 to 1.20%, Mg: 0.50 ˜1.70%, Zn: 0.30% or less, Ti: 0.15% or less, with the balance being composed of Al and inevitable impurities, and α conversion of 89% or more Characteristic aluminum alloy plate for can body.   A method for producing an aluminum alloy sheet for a can body, comprising subjecting the aluminum alloy material having the composition according to claim 1 to a homogenization treatment under conditions of a holding temperature of 565 ± 10 ° C and a holding time of 4 to 10 hours.   A method for producing an aluminum alloy sheet for a can body, comprising subjecting the aluminum alloy material having the composition according to claim 1 to a homogenization treatment a plurality of times under conditions of a holding temperature of 565 ± 10 ° C and a holding time of 2 hours or more. .   The method for producing an aluminum alloy plate for a can body according to claim 3, wherein a total holding time of the plurality of homogenization treatments is 4 to 10 hours.   The hot rolling and cold rolling are performed after completion of the homogenization treatment, and at least one intermediate annealing is performed after the hot rolling or during the cold rolling. The manufacturing method of the aluminum alloy plate for can bodies as described.