JP3069008B2 - Method for manufacturing aluminum alloy DI can body - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a can body for a two-piece aluminum can by DI working (drawing and ironing), that is, a DI can body made of an aluminum alloy, and more particularly to a method after DI working and paint baking. The present invention relates to a method for obtaining an aluminum alloy can body having good formability in, for example, flange processing performed on a can body edge (flange portion).

[0002]

2. Description of the Related Art In general, as a manufacturing process of a two-piece aluminum can, a body material is subjected to DI drawing by deep drawing and ironing to form a can body and then trimming to a predetermined size. A paint baking process is applied, then necking (mouth drawing) and flange processing (mouth opening) are performed on the can body edge, and a separately formed can lid (can end) is combined with a seaming process (rolling). Is usually performed.

By the way, as a can body material of a conventional DI can,
JIS 3004 alloy and AA 3104 alloy, which are Al-Mg-Mn alloys, are widely used. These alloys are excellent in ironing workability and, even when cold-rolled at a high rolling ratio in order to increase strength, show relatively good formability, making them ideal as DI can body materials. It has been.

[0004]

The two-piece aluminum can is made thinner to reduce material cost.
It is strongly desired to reduce the weight. In order to reduce the thickness, it is desired to further increase the strength. The DI can body is required not only to have high strength but also to have good DI formability. Further, necking, flanging, and seaming after forming the DI can body and applying a paint baking treatment are required. Excellent formability in processing is also required. In particular, the can body edge is subjected to multiple steps and various kinds of processing such as cold rolling in the material manufacturing process, DI forming at the time of forming the can body, necking after painting and baking, flanging, and seaming. Therefore, cracks are likely to occur during processing. Especially recently, the thickness of the can body edge has become smaller with the thinner can body.
For this reason, the flange is easily broken at the edge during the flanging or seaming, so that the flangeability of the can body edge,
Improvement in seamability is strongly desired. In addition, a reduction in the neck diameter of the can body has been demanded in view of the demand for a lighter can lid. In this case, an increase in the amount of necking is required, so that the formability of the can body edge is further improved. Is desired.

The inventors of the present invention have conducted intensive experiments and studies to solve the above-mentioned problems, and as a result, while appropriately selecting the alloy composition of the raw material, at the same time, optimizing the structural state, particularly the structural state of the can body edge. By forming a structure in which the can body edge has 10% or more of sub-crystal grains (sub-grains), D
As a DI can body subjected to I processing and paint baking treatment, it was found that a DI can body excellent in formability at the edge was obtained, and the applicant of the present application has already filed the invention on May 25, 1994. We have filed a patent application for the name "DI can body made of aluminum alloy".

That is, as a result of repeated experiments on the moldability of the can body edge by the present inventors, the presence of sub-crystal grains in the can body edge has a great influence on the formability, especially on the flange workability. The ratio of sub-crystal grains (sub-grains) in the metal structure of the can body edge is 10% or more in terms of area ratio, that is, the sub-grain ratio is 10% or more. It was found to be effective in improving the moldability, ie, necking workability, flange workability, and seaming workability. In this way, 10
% Or more (preferably 20% or more) of sub-crystal grains, dislocations (work strain) given by necking, flanging, and seaming are absorbed by the sub-crystal grain boundaries. It has been found by the present inventors that good moldability can be obtained with almost no work hardening.

The present invention has been made in view of the above circumstances, and as described above, a can body having a structure in which the can body edge has a sub-crystal grain of 10% or more, preferably 20% or more, is ensured. In addition to the strength and DI moldability, it is possible to reliably and stably produce a can body excellent in moldability of the can body edge, that is, in necking processing, flange processing, and seaming processing. It is an object of the present invention to provide a method for manufacturing a DI can body made of an aluminum alloy.

[0008]

The present inventors have conducted intensive experiments and researches to solve the above-mentioned problems, and as a result, from the final recrystallization in the manufacturing process of the material for the can body, to the finishing plate thickness (final cold working). Degree of cold work up to can body material thickness after rolling) and DI
By appropriately setting the relationship between the temperature and the time at the time of the heat treatment such as the drying treatment and the paint baking treatment after the processing with a predetermined correlation, the structure in which the sub-crystal grains of the can body edge occupy 10% or more can be obtained. They have found that they can be obtained with certainty, and have accomplished the present invention.

Specifically, the present invention relates to
1.5%, Mn 0.5-1.8%, Fe 0.1-0.8
%, Si 0.05-0.5%, Cu 0.05-0.7%
Containing, and the balance is cast of an alloy consisting of Al and unavoidable impurities, and subjected to soaking, hot rolling and cold rolling to finish to a predetermined thickness, and from hot rolling to halfway through cold rolling. In a method for manufacturing an aluminum alloy DI can body in which the can body material having a finished plate thickness after cold rolling is further subjected to DI processing and heat treatment including painting baking treatment, the final recrystallization the thickness of the t ₂ the thickness finish with a t _1, a cold-rolled sheet Atsuma strain epsilon up thickness finish from the time the final recrystallization is defined as _{ε = ln (t 1 / t} 2), and The heat treatment temperature after DI processing is T (K), the activation energy of self-diffusion of aluminum is Q, the gas constant is R, and the self-diffusion D of aluminum is D = exp.
(-Q / RT), the Mg amount (% by weight) is defined as Mg%, and the heat treatment time after DI processing is t (sec).
The rate of cold working from the time of final recrystallization to the thickness of the finished plate, the temperature of the heat treatment after DI working and the temperature are set so that the following formula ε ³ × D × ln (t) / (Mg%) ⁴ > 1 is satisfied. By controlling the time, a DI can body having a sub-crystal grain of 10% or more in the can body edge after the paint baking treatment is obtained.

[0010]

In the manufacturing method of the present invention, basically,
The relationship between the degree of cold work after the final recrystallization and the temperature during coating baking is important, but as a prerequisite, the alloy composition of the material is also important, and the composition should be within the specified range. Only by doing so can the intended purpose be achieved. Therefore, the reason for limiting the component composition of the material alloy will be described first.

Mg: Mg is an element that is effective for solid solution strengthening even when used alone, and is an element indispensable for improving strength. Further addition of Mg is, Mg by coexistence of Si and Cu ₂ Si
Alternatively, age hardening due to precipitation of the Al-Cu-Mg phase can be expected. In particular, in the present invention, the amount of Mg has a great effect on subgraining (subcrystallization) in correlation with the degree of cold working after final recrystallization described later and the heating conditions after DI processing such as paint baking. give. Mg content is 0.1
%, The required strength cannot be obtained. On the other hand, if it exceeds 1.5%, sufficient strength can be obtained, but subgraining (sub-graining) is significantly delayed, and It is difficult to stably secure an occupation ratio of 10% or more of the sub-crystal grains, thereby deteriorating the formability of the body portion of the can, especially the flange workability. Therefore, the range of Mg is 0.1 to
1.5%.

Mn: Mn is an element effective for contributing to improvement in strength and formability. Particularly, in the manufacturing process of the can body targeted by the present invention, Mn is important because severe ironing is performed during DI molding. Emulsion type lubricants are usually used for ironing aluminum plate, but when the amount of Mn-based crystals is small, lubricating ability is insufficient with only emulsion type lubricants even if they have the same strength. However, there is a possibility that poor appearance such as abrasion and seizure called galling may occur. It is known that this phenomenon is affected by the size, amount, and type of the crystallized material, and Mn is indispensable for forming an appropriate Mn-based crystallized material and improving the lubricating ability in ironing. Element. If the Mn content exceeds 1.8%, a primary MnAl ₆ intermetallic compound is generated, and conversely, the formability is significantly impaired. If the Mn content is less than 0.5%, the solid lubrication effect of the Mn-based compound cannot be obtained. Therefore, the range of Mn is set to 0.5 to 1.8%.

Fe: Fe promotes crystallization and precipitation of Mn,
It is an element necessary for controlling the amount of Mn solid solution in the aluminum matrix and the dispersion state of the Mn-based insoluble compound. In order to obtain an appropriate compound dispersion state, the amount of F
It is necessary to add e. If the Fe content is less than 0.1%, it is difficult to obtain a proper compound dispersion state, whereas if the Fe content is 0.8% or more, a primary crystal giant compound is likely to be generated with the addition of Mn. Significantly impairs the performance.
Therefore, the range of Fe is set to 0.1 to 0.8%.

Si: The addition of Si contributes to age hardening due to precipitation of Mg ₂ Si-based compounds. Si content is 0.05%
If the amount is less than 0.5%, the effect cannot be obtained. If the amount exceeds 0.5%, age hardening is easily obtained, but the material becomes too hard and the moldability is impaired. Therefore, the range of Si is 0.05 to 0.5.
%.

Cu: The addition of Cu contributes to age hardening due to the formation of Al-Cu-Mg based precipitates. Cu content is 0.
If the content is less than 0.05%, the effect cannot be obtained.
%, Age hardening is easily obtained, but becomes too hard, impairing moldability and deteriorating corrosion resistance. Therefore, the range of Cu is 0.05 to 0.7.
%.

In addition, in ordinary aluminum alloys, it is common to add a small amount of Ti alone or in combination with B to refine the ingot crystal grains. Also in the present invention, trace amounts of Ti or Ti and B can be added. However, if the Ti content is less than 0.005%, the effect cannot be obtained.
Since l ₃ is crystallized and impairs formability, the Ti content is 0.0
It is desirable that the content be in the range of 0.5 to 0.20%. When B is added together with Ti, the effect is not obtained if the B content is less than 0.0001%, and if it exceeds 0.05%, coarse particles of TiB ₂ are mixed to impair the formability. 0.000
A range of 1 to 0.05% is desirable.

Further, in addition to the above-mentioned elements, it is permissible to add 0.3% or less of Cr and 0.5% or less of Zn as necessary for improving the strength. That is, Cr is an element effective for improving the strength. However, if the Cr content exceeds 0.3%, the formability is reduced due to the formation of giant crystals.
Cr is set to 0.3% or less. The addition of Zn is Mg ₂ Z
It contributes to the strength improvement by aging precipitation of n ₃ Al ₂ ,
If the n content exceeds 0.5%, the corrosion resistance deteriorates.

The balance of each of the above elements may be Al and inevitable impurities.

Next, the manufacturing process in the method of the present invention will be described.

First, a molten alloy having the above-described composition is melted according to a conventional method, and is cast by a normal casting method such as a DC casting method (semi-continuous casting method). The obtained ingot is subjected to a homogenizing treatment (soaking heat treatment). This homogenization treatment may be performed under ordinary conditions, for example, at 500 to 620 ° C. × 1 hour or more. Further, the ingot after the homogenization treatment is hot-rolled to obtain a hot-rolled sheet having a required thickness. Although the conditions of the hot rolling are not particularly limited, it is preferable to perform rolling in a temperature range of 580 to 200 ° C. in consideration of hot rollability and surface quality. If the hot rolling temperature exceeds 580 ° C., the surface quality may be degraded due to the oxide film on the surface during hot rolling, and if it is less than 200 ° C., the deformation resistance is too large and the rollability deteriorates.

After the hot rolling as described above, the plate is finished to a predetermined thickness of the can body material by cold rolling. After such hot rolling, in the process up to the finished plate thickness, the structure in the plate is recrystallized at least once. For that purpose, usually, recrystallization annealing is performed immediately after hot rolling and recrystallization is performed, and then cold rolling (final cold rolling) is performed to a finished plate thickness, or primary cold rolling is performed after hot rolling. In general, rolling is performed to the intermediate sheet thickness, then recrystallization annealing is performed to recrystallize, and then cold rolling (final cold rolling) is performed to the finished sheet thickness, but in some cases, hot rolling is performed. During coiling and subsequent cooling process, recrystallization by heat retained in hot-rolled coil (recrystallization by self-annealing)
After that, cold rolling (final cold rolling) may be performed to the finished plate thickness without particularly actively performing recrystallization annealing.

When recrystallization annealing is performed after hot rolling or further after primary cold rolling, the recrystallization annealing may be performed according to a conventional method. C. × 10 minutes or less is preferable, and when batch annealing is applied, 300 to 450 ° C. ×
A condition of 1 to 10 hours is desirable. In the case of continuous annealing, if the temperature is less than 450 ° C., recrystallization is incomplete, while if it exceeds 600 ° C., eutectic melting may occur, and a strong oxide film may be formed on the surface, resulting in cold rollability.
Even when the appearance is impaired and the holding time exceeds 10 minutes, a strong oxide film is formed on the surface and the cold rolling property and
The appearance may be impaired. On the other hand, in the case of batch annealing, if the temperature is less than 300 ° C. or the holding time is less than 1 hour, recrystallization becomes insufficient. If the temperature exceeds 450 ° C., a strong oxide film is formed on the surface, and the cold rolling property and appearance If the holding time exceeds 10 hours, the effect of recrystallization saturates, and only the economic efficiency is deteriorated.

When primary cold rolling is performed before recrystallization annealing, the cold rolling reduction is not particularly limited.

After recrystallization by recrystallization annealing or self-annealing following hot rolling, cold rolling is performed to a finished plate thickness. The final cold rolling has a large effect on the sub-grain ratio after the coating baking process, as described later, depending on the relationship between the amount of Mg and heating conditions such as the coating baking process after the DI processing. Therefore, although the working ratio of the final cold rolling cannot be specified alone, generally speaking, the larger the working ratio, the easier it is to increase the sub-grain ratio, and usually, the larger the working ratio, the lower the rolling ratio.
% Or more is preferable.

[0025]

The final cold-rolled sheet is used as a can body material, subjected to DI processing by deep drawing and ironing, subjected to predetermined trimming to form a can body, and further washed, dried, and coated on the inner surface of the can. And paint baking, outer surface painting of the can and paint baking. After necking and flange processing are further performed, the contents are filled, a can lid is attached, and seaming is performed.

In the drying process after DI processing, trimming, and washing, and in each coating baking process for the inner surface coating and the outer surface coating, heating for a total of about 2 to 30 minutes at a temperature in the range of 180 to 250 ° C. is generally performed. Done. The material is softened by heating in such drying and painting baking,
Sub-crystal grains are formed as a structural change at this time.

That is, generally, when heat treatment is performed on an aluminum alloy material into which strain (accumulation of dislocations) has been introduced by cold working, the dislocation density decreases and the cell walls having a small misorientation become small angle grain boundaries (subgrains). ), And sub-grains (sub-grains) are generated. Here, if the temperature of the above-mentioned heat treatment is higher than a certain level, the sub-crystal grains are further coarsened, and in this process, the re-crystallized crystal grains are formed with the grown grains of the sub-crystal grains serving as nuclei, thereby producing a recrystallized structure. However, at a temperature of about the drying and painting baking treatment after DI processing, it does not usually proceed until recrystallization. In the case of a DI can body, cold working is performed by final cold rolling after the final recrystallization in the plate manufacturing process and ironing in the subsequent DI forming, and cold working strain (dislocation) is introduced. Therefore, by appropriately adjusting the cold working strain under an appropriate Mg content, by appropriately selecting heating conditions such as drying and paint baking after the can body molding,
Sub-crystal grains can be appropriately generated by a heat treatment such as drying and baking. The present inventors have conducted a number of experiments on the moldability of the can body edge, and as a result, the existence of sub-crystal grains in the can body edge indicates that the formability,
In particular, it greatly affects the flange workability, and the ratio of subcrystal grains in the metal structure of the can body edge is 10% in area ratio.
It has been found that what is described above, that is, that the sub-grain ratio is 10% or more is effective for improving the moldability of the can body edge, that is, necking workability, flange workability, and seaming workability.

If at least 10% of sub-crystal grains are present at the can body edge, preferably at least 20% of sub-crystal grains are present,
Dislocations (working strain) given by necking, flanging, and seaming have little accumulation of dislocations absorbed in the sub-grain boundaries, so that there is almost no work hardening during these processes and good formability. Is obtained. In addition, as a result of many observations, it was confirmed that the sub-crystal grains generated by the coating baking process, even if a process such as necking was added thereafter, continued to exist as it was, although there was a slight increase in dislocation density. I have. Subgrain rate is 10
If it is less than%, dislocations are accumulated by necking, flanging, and seaming, so that remarkable work hardening occurs and the moldability of the can body deteriorates.

As described above, in order to achieve a sub-grain ratio of 10% or more, preferably 20% or more by the heat treatment after DI processing, it is necessary to use Mg among the components of the can body material.
It is necessary to appropriately combine the amount, the degree of cold working after final recrystallization, and the heat treatment conditions after DI working. Here, the degree of cold working after final recrystallization is strictly defined as the degree of cold working (cold rolling rate) in final cold rolling, and the degree of working of the can body edge during DI working, particularly ironing. (Change in sheet thickness), but in reality, the ratio of the workability at the time of ironing to the total cold workability after the final recrystallization is small. Therefore, in determining the relationship between the three,
The degree of cold work after final recrystallization can be represented by the degree of work of final cold rolling. That is, in this case, 10%
In order to obtain the above-mentioned sub-grain ratio, the following three conditions, namely, the amount of Mg, the working degree of the final cold rolling after the final recrystallization, and the heat treatment conditions after the DI working are set so as to satisfy the following equation (1). It may be determined relatively. ε ³ × D × ln (t) / Mg ⁴ > 1 × 10 ⁻⁸ (1)

Here, ε is the true strain of the cold-rolled sheet thickness corresponding to the degree of work in the final cold rolling after the final recrystallization, ie, the sheet thickness at the time of the final recrystallization, t ₁ , and the finished sheet after the final cold rolling. Assuming that the thickness is t ₂ , it is a value represented by ε = ln (t ₁ / t ₂ ) (2). D is the self-diffusion of aluminum, and is represented by D = exp (−Q / RT) (3) Where Q is the activation energy of self-diffusion of aluminum, R is the gas constant, T is the temperature of the heat treatment after DI processing (K), and t is the time of heat treatment after DI processing (se).
c). Mg is the amount (weight ratio) of Mg in the material alloy.

The above equation (1) was obtained as follows. That is, the sub-grains are formed when the dislocation is thermodynamically liable to move. Therefore, qualitatively, the larger the degree of cold working up to DI working,
Subgraining is promoted as the heat input during drying and paint baking after I processing is larger and the amount of Mg that has the effect of delaying the recovery of dislocation is smaller. Therefore, each factor contributing to subgrain formation was specifically examined.

The true strain ε corresponding to the cold rolling reduction from the final recrystallized sheet thickness is an important factor, and greatly contributes to subgrain formation. The amount of heat input in the drying and baking processes after DI processing is related to the heating temperature and time. In particular, the heating temperature T affects the rearrangement speed of dislocations due to subgrain formation, that is, the moving speed of atoms. It is necessary to arrange the activation energy based on the diffusion of aluminum, the gas constant R, and the heating temperature T in an exponential function. Regarding the heating time t, the longer the time, the more the subgrain formation proceeds, but the logarithmic relationship is appropriate rather than a linear relationship. Further, Mg is an element that suppresses sub-grain formation, and if the amount of Mg is large, sub-grain formation is significantly delayed. As a result of many experiments conducted by the present inventors, the final cold-rolled sheet thickness true strain ε governing the sub-grain ratio, the heating temperature T after DI processing, the heating time t, and the amount of added Mg (weight ratio) are as follows. They found that they can be arranged in the third power, the first power, the natural logarithm, and the fourth power, respectively. In order to stably maintain a subgrain ratio of 10% or more in order to improve the moldability of the can body edge, the left side of equation (1) needs to exceed 1 × 10 ^−8. Was.

In the equation (1), the amount of Mg is represented by a weight ratio, but when represented by a weight percentage (Mg%), the following expression is obtained.
The expression is rewritten as the following expression (4). ε ³ × D × ln (t) / (Mg%) ⁴ > 1 (4)

Therefore, it is necessary that the left side of the equation (4) exceeds 1 in order to secure a sub-grain ratio of 10% or more, and this is defined in claim 1 of the present invention.

As described above, in the actual can manufacturing process, there are several heat treatments after the DI processing, such as DI processing, drying after washing, coating baking after internal coating, and coating baking after external coating. Heating and cooling are repeated. Therefore, D × ln (t) in the equations (1) and (4) should be expressed as the sum of these heating steps. That is, when the drying, the inner coating baking process, and the outer coating baking process are performed as the heating process after the DI processing, the formula (1) is used.
D × ln (t) in the equation (4) is [D × ln in drying step]
(T)] + [D × ln (t) at the time of baking inside paint] +
It is expressed as the sum of [D × ln (t) at the time of baking the outer surface coating].

In deriving the above equations (1) and (4), the influence of the degree of cold working after the final recrystallization is as shown in the equation (2). Only the degree of work (rolling rate) in cold rolling is considered. Strictly speaking, as described above, even in the DI processing (deep drawing and ironing), the cold working is performed and the sheet thickness is slightly reduced, so that the DI processing also slightly affects the sub-grain formation. Will be given. However, in cold rolling → deep drawing → ironing, since the respective processing modes are different, the accumulation forms of dislocations are different, and it is not possible to simply consider the sum of all the processing rates. The present inventors have sufficiently considered this point, and have examined the definition of processing strain as a factor that has a large effect on the change in the subgrain ratio and can be easily adjusted in actual industrial can body manufacture. The processing strain from the final recrystallized sheet thickness to the final cold-rolled sheet thickness contributes most to the sub-graining rate and can be actually adjusted. Formula (4) using the processing strain up to the thickness as a control factor was found to be the most practical.

As described above, by appropriately setting the amount of Mg, the degree of cold working after final recrystallization, and the temperature and time of the heat treatment after DI working so as to satisfy the expression (4), It is possible to reliably and stably obtain a can body having a sub-grain ratio of 10% or more at the edge. The sub-grain ratio of the can body edge is thus 10% or more (preferably 20%).
By the above, not only the strength and the DI processability are excellent, but also the formability (necking processability,
It is possible to obtain a DI can body excellent in flange workability and seaming workability).

[0039]

EXAMPLES For each alloy having the composition shown in Table 1, alloy numbers 1 to 7 were subjected to DC casting in accordance with a conventional method, and the obtained ingot was subjected to soaking treatment and then subjected to hot rolling to obtain various thicknesses. A hot rolled sheet was used. The obtained hot-rolled sheet was subjected to recrystallization annealing under the conditions shown in Table 2, and then cold-rolled to finally obtain a sheet thickness of 0.3 mm. In addition, about a part, the primary cold rolling is performed on the hot-rolled sheet to make the intermediate sheet thickness, and then the recrystallization annealing is performed. Then, the final cold rolling is performed, and the sheet thickness is finally reduced to 0.3 mm as described above. did. Further, DI forming is performed using each cold-rolled sheet according to a conventional method, and thereafter, at various temperatures and temperatures.
A heat treatment was performed under the conditions shown in Table 2 assuming a paint baking treatment over a period of time.

With respect to the DI can body obtained as described above and subjected to the heat treatment corresponding to the paint baking treatment, the subgrain ratio at the edge was measured by a transmission electron microscope. The results are shown in Table 3. Further, the mouth expandability after necking was performed according to a conventional method was examined. This mouth-opening property was evaluated by pushing a taper punch having an inclination angle of 30 ° with respect to the can body wall into the open end after the necking process and increasing the radius of the can end until the edge was broken. In this mouth expandability evaluation, the larger the evaluation value (the amount of increase in radius), the better the flange workability.
It is empirically known that when the thickness is less than (mm), the flange properties are inferior. Furthermore, the strength after the paint baking treatment was examined, and the seaming workability after necking and flange working was examined. The results are also shown in Table 3. Here, the strength after the paint baking treatment was determined on the assumption that the bottom pressure resistance, which is the most problematic in the DI can body, was applied to the base plate after the paint baking treatment as described above. If the strength after the baking treatment is 260 N / mm ² or less, it is evaluated as unsuitable as a can body requiring pressure resistance. In addition, the seamability was evaluated by actually performing a seaming process on each of 20 cans with a can lid attached. When one of the cans had a crack at the can body edge, the X mark indicates that none of the cans had a crack. The case was marked with a circle.

Table 3 also shows the value of the true strain ε of the cold-rolled sheet thickness after the final recrystallization and the value on the left side of the equation (4).
Here, in the calculation of the value on the left side of the equation (4), the activation energy Q of aluminum was 37 kcal / mol and the gas constant R was 1.986 cal / mol / K.

[0042]

[Table 1]

[0043]

[Table 2]

[0044]

[Table 3]

In Tables 2 and 3, production numbers 5, 7, 1
In each of the cases of 1 and 14, the value on the left side of the equation (4) was smaller than 1, so that the sub-grain ratio was less than 10%. In each of these cases, the moldability of the can body edge was inferior, and cracks occurred during seaming. Among them, Production No. 5 is an example in which the composition of the alloy is within the range of the present invention, but the subgrain formation did not sufficiently proceed because the temperature of the heat treatment equivalent to paint baking was low. In the case of (1), subgrain formation was delayed because the amount of Mg in the alloy was large. Production numbers 10 to 15 are the same alloys (with the exception of Mg) within the component composition range specified in the present invention.
(The amount is close to the upper limit.) This is an example in which the conditions for manufacturing the can body material and the conditions for the heat treatment equivalent to the baking of the coating were changed. In the case of the production number 10, the final cold rolling reduction was increased, and , 13 and 15, a subgrain rate of 10% or more can be sufficiently achieved by applying an appropriate combination such as raising the temperature of the coating baking equivalent heat treatment or lengthening the time. Good formability of the can body edge could be secured. On the other hand, the production number 11 has a low final cold-rolling reduction rate and a relatively short heat treatment time equivalent to coating baking, so that even if the same alloy is used, the sub-grain ratio is low, and the can body edge forming is excellent. Sex was not obtained. Production No. 14 is an example in which the temperature of the heat treatment equivalent to coating baking was further lower than that of Production No. 11, but also in this case, the subgrain ratio was low and the moldability of the can body edge was inferior. . From these examples, it is possible to appropriately set the Mg content of the alloy, the reduction ratio of the final cold rolling, the temperature and the time of the heat treatment after the DI processing so as to satisfy the above-mentioned formula (4), and obtain a sub-grain ratio of 10 % Or more,
It turns out that it is necessary to obtain good can body shape.

Further, in the case of Production No. 1, although the sub-graying ratio was sufficient, a predetermined strength as a can body could not be obtained because Mg was not substantially added. In the case of Production No. 9, although the sub-grain ratio was achieved, since the amount of added Mn was excessive, many Mn-based compounds tended to be the starting points of cracking during flange processing,
The primary intermetallic giant intermetallic compound was generated and deteriorated the formability of the body of the can. In the case of Production No. 8, the moldability and strength of the body edge of the can were sufficient, but the amount of Mn added was too small, and the solid lubricating effect of the Mn-based compound was not obtained.
As a result, intense galling occurred during DI processing, which markedly impaired the appearance of the can and caused remarkable adhesion of aluminum to the die.

On the other hand, at the same time that the alloy component composition satisfies the range specified in the present invention, the value on the left side of the equation (4) is set to 1 by an appropriate combination of the amount of Mg, the material production conditions, and the heat treatment conditions equivalent to paint baking. In the case where the rate of subgrain formation exceeds 10% (example of the present invention), all of the strength, DI processability, and can body edge formability are excellent.

In the examples of the present invention, production numbers 3, 4,
Nos. 6, 12, 13, 15 appropriately balance the strength and the moldability of the can body edge. Production number 2 is Mg
This is an example in which the addition amount is low, and a certain strength is secured, while emphasizing particularly on the moldability of the can body edge. In addition, the production number 10 shows that the strength of the can body edge is secured while securing a certain degree of moldability. This is an example where emphasis is placed on. Therefore, it is clear from these that a DI can body having necessary strength and can body edge formability can be manufactured with a large degree of freedom by appropriately controlling alloy components and manufacturing conditions.

[0049]

According to the present invention, the composition of the material alloy is appropriately adjusted, and particularly the amount of Mg in the material alloy, the degree of cold working after the final recrystallization, and the heat treatment after the DI working. By appropriately combining the temperature and the time, as the DI can body subjected to the DI processing and the paint baking treatment, the metal structure state of the can body edge portion, particularly, subcrystal grains (subgrains) occupies 10% or more. With such a structure, the D is excellent in the formability of the can body edge, that is, the formability in necking processing, flange processing, seaming processing, etc., without impairing the strength and DI processability.
I can body can be obtained. Therefore, the DI of the present invention
According to the method for manufacturing a can body, it is possible to effectively prevent occurrence of molding defects such as breakage of a can end due to work hardening in necking, flange processing, and seaming processing, and to reduce the processing load to reduce the processing load. It is possible to effectively prevent buckling and the like from occurring on the can body at times, and it is possible to further reduce the weight of the can by reducing the diameter of the can body neck and reducing the diameter of the can lid. Become.

────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI C22F 1/00 673 C22F 1/00 673 686 686B 691 691B 691C 694 694A (56) Reference JP-A-4-59952 (JP, A) JP-A-5-33107 (JP, A) JP-A-7-316707 (JP, A) JP-A-6-228696 (JP, A) Shiina, Teruta, Komatsubara , Murakami, "Effects of Rapid Heat Annealing Conditions on Cube Texture Formation in 3004 Aluminum Alloy", Abstracts of the Conference of the Japan Institute of Light Metals, Vol. 84th P. 77-78 (1993) (58) Field surveyed (Int. Cl. ⁷ , DB name) C22F 1/04-1/057 C22C 21/00-21/18

Claims (1)

(57) [Claims] 1. Mg 0.1-1.5% (weight%, the same applies hereinafter), Mn 0.5-1.8%, Fe 0.1-0.8%,
An alloy containing 0.05 to 0.5% of Si and 0.05 to 0.7% of Cu and the balance consisting of Al and unavoidable impurities is cast and subjected to soaking, hot rolling and cold rolling to obtain a predetermined alloy. Finished to a thickness, and recrystallized between hot rolling and halfway through cold rolling. In the method for producing a DI can body made of aluminum alloy, the thickness at the time of final recrystallization is set to t ₁ and the finished plate thickness is set to t.
_{As 2} , the true strain ε of the cold-rolled sheet thickness from the last recrystallization to the finished sheet thickness is defined as ε = ln (t ₁ / t ₂ ), and DI
The heat treatment temperature after processing is T (K), the activation energy of self-diffusion of aluminum is Q, the gas constant is R, and the self-diffusion D of aluminum is D = exp (-Q / RT).
And the Mg amount (% by weight) is defined as Mg%, and DI
Assuming that the heat treatment time after the processing is t (sec), cold working from the time of the final recrystallization to the thickness of the finished plate is performed so that the following expression ε ³ × D × ln (t) / (Mg%) ⁴ > 1 is satisfied. Rate, and the temperature and time of the heat treatment after the DI processing are controlled to obtain a DI can body having a sub-crystal grain of 10% or more after the baking treatment. A method for manufacturing an aluminum alloy DI can body having excellent moldability of a part.