JP3210419B2 - Aluminum alloy sheet for DI can excellent in flange formability and method for producing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an aluminum hard plate excellent in strength and formability, and also excellent in formability after baking after forming, and a method for producing the aluminum hard plate. The present invention relates to an Al-Mg-Mn-based aluminum alloy hard plate for a two-piece aluminum can (DI can) which is excellent in flange formability after baking treatment suitable for a can body material of a DI can and a method for producing the same.

[0002]

2. Description of the Related Art In recent years, aluminum alloy sheets used as can materials have been reduced in thickness and strength. This is due to economic demands such as reducing costs by using thinner plates having higher strength. JIS
Since the 3004 alloy hard plate has relatively good formability even when cold-rolled at a high rolling rate in order to increase the strength, it is often used for such a can body material conventionally. Was. This JIS 3004 alloy hard plate is often manufactured by performing hot rolling according to a conventional method after homogenization treatment, and then performing intermediate annealing with or without performing cold rolling. On the other hand, with the spread of continuous annealing furnaces (CAL) in recent years, it has become possible to carry out intermediate annealing of high temperature and rapid cooling, and as a result, the mainstream has been the production of can body materials that have been strengthened by using the solution effect. It is getting. According to this method, the strength at the time of DI molding does not need to be as high as that of the conventional batch-type intermediate annealed material, so that the DI moldability is good because the strength does not decrease much after baking.

[0003]

As described above, the thickness of the can body has been reduced, but DI molding has been performed in proportion to the reduction in the thickness of the original plate before molding. Later can sidewalls also become thinner. Conventionally, the thickness of the flange forming part of the side wall is 2
What is about 00 μm is now thinner to about 150 μm, and tends to be even thinner. However, when the thickness of the flange-formed portion is reduced, ductility is reduced, cracking sensitivity at the time of forming is increased, and flange-formability is deteriorated.

[0004] The present invention is based on the conventional JIS 30
Ear ratio, strength, based on alloy system different from 04 alloy
Characteristics such as DI moldability are equal to or higher than conventional materials,
Moreover, it is an object of the present invention to provide a material suitable for a can body material excellent in flange formability and seaming formability.

[0005]

Means for Solving the Problems In order to achieve the above object, the present inventors have conducted comprehensive studies on chemical composition adjustment, structure, manufacturing conditions, etc.
-It has been found that the above object can be achieved by restricting the components of Fe and Si and setting an appropriate intermetallic compound dispersion state and an appropriate Mn solid solution amount.

That is, according to the present invention, Mg: 0.5-2.0%, Mn: 0.6-1.
4%, Cu: 0.05-0.5%, Fe: 0.3-1.
0%, Si: 0.15 to 0.5%, and Ti: 0.005 to 0.2% for fineness and stabilization of the structure alone or together with B: 0.0001 to 0.05%. , 1 ≦ M
n / Fe ≦ 2.5, 3 ≦ Mn / Si ≦ 4, 1% ≦ Fe +
The condition of Mn ≦ 2% is satisfied, and Cr: 0.05 to
0.3%, Zn: one or two of 0.1 to 0.5%, the balance being Al and unavoidable impurities, and an intermetallic compound of 5 μm or more on the plate surface of 100%
２００200 / 0.2 mm ² , Mn solid solution amount is 0.1
An aluminum alloy sheet for a DI can excellent in formability, particularly excellent in flange formability after DI forming, characterized in that it is not more than 6%.
g: 0.5-2.0%, Mn: 0.6-1.4%, C
u: 0.05 to 0.5%, Fe: 0.3 to 1.0%, S
i: 0.15 to 0.5%, and Ti: 0.005 to 0.2% alone or B: 0.
0001-0.05%, 1 ≦ Mn / Fe
≦ 2.5, 3 ≦ Mn / Si ≦ 4, 1% ≦ Fe + Mn ≦ 2
%, And Cr: 0.05 to 0.3%,
Zn: An aluminum alloy ingot containing one or two of 0.1% to 0.5%, the balance being Al and unavoidable impurities is subjected to soaking and then hot-rolled. After performing cold rolling, annealing is performed at a heating / cooling rate of 1 ° C./s or more at a temperature of 400 to 600 ° C. and a holding time of 10 minutes or less, and then cold rolling at a rolling rate of 40% or more is performed. And there are 100 to 200 intermetallic compounds of 5 μm or more on the plate surface / 0.2 mm ² , and Mn
This is a method for producing an aluminum alloy sheet for a DI can having excellent formability, particularly having excellent flange formability after DI forming, characterized in that the solid solution amount is 0.16% or less.

Hereinafter, the present invention will be described in more detail. First, the reasons for limiting the chemical components in the present invention will be described. Mg: Mg is expected to improve the strength by aging precipitation of Mg ₂ Si or Al—Cu—Mg in coexistence with Si and Cu, and particularly in the case of intermediate annealing having a solution effect as in the present invention, especially after coating baking. It is effective in suppressing a decrease in strength. Furthermore, Mg alone is effective in improving strength by solid solution strengthening. As described above, it is an indispensable element for improving the strength. However, if the amount of Mg is less than 0.5%, the effect is small and sufficient strength cannot be obtained. Although there is no problem with respect to the above point, work hardening becomes easy, so that redrawability and ironing property are deteriorated. Therefore Mg
The amount ranges from 0.5 to 2.0%. Mn: Mn is an element that contributes to improving strength and is effective for improving formability. In particular, Mn is particularly important in the can body material, which is an application aimed at by the present invention, in order to be ironed. In the ironing of an aluminum alloy plate, an emulsion type lubricant is usually used. However, in the case of a structure with a small number and amount of Mn-based crystallized substances, even if they have the same strength, the lubricating ability is insufficient with the emulsion type lubricant alone, and poor appearance such as abrasion and galling called galling Occurs. This phenomenon is affected by the size, amount, and type of the crystallized matter, and it is essential to add an appropriately selected amount of Mn. Solid solution Mn greatly contributes to strength improvement, but does not contribute to strength like Mg to improve ductility, but has the effect of making the material brittle. FIG. 1 shows the influence of Mn solid solution amount on ductility by measuring the critical flange elongation as an evaluation of ductility. Mn
It can be seen that the ductility is not reduced when the solid solution amount is up to 0.16%, but the ductility is decreased as the solid solution amount increases when it exceeds 0.16%. Therefore, the Mn solid solution amount is 0.1
6% or less. If the Mn content is less than 0.6%,
The compound cannot provide a solid lubricating effect, but 1.4.
%, It is mixed with Fe described later, and (Mn, F
e) out primary crystal coarse intermetallic compound of Al ₆ crystallizes, it intends significantly impair the moldability. Further, the solid solution amount of Mn increases as the added amount of Mn increases.
Even if the amount of n added is large, the amount of Mn solid solution can be adjusted. However, when the amount of added Mn exceeds 1.4%, the amount of Si,
It is difficult to suppress the amount of Mn solid solution even by the amount of Fe. Therefore, the amount of Mn is set to 0.6 to 1.4%. Cu: In the present invention, an improvement in strength due to the solution effect of Cu can be expected. In other words, the Al-Cu-M
It is an element that contributes to strength improvement by utilizing age hardening that occurs during the precipitation process of g-based precipitates. When the amount of Cu is less than 0.05%, the effect cannot be obtained. On the other hand, when the amount exceeds 0.5%, age hardening is easily obtained but becomes too hard to inhibit moldability. Therefore, the amount of Cu is 0.05-0.
The range is 5%. Fe: Fe is an element that promotes crystallization and precipitation of Mn, and is necessary for controlling the solid solution amount of Mn in the aluminum matrix and the dispersion state of the Mn-based insoluble intermetallic compound. A necessary condition for obtaining an appropriate state is the addition of Fe according to the amount of added Mn. When Mn / Fe is more than 2.5, the solid solution amount of Mn increases and ductility is deteriorated. When the value of Mn / Fe is small, the crystallized compound becomes fine and the ductility generally improves. However, when the value is less than 1, the size of the crystallized product becomes too small, and the lubricating effect at the time of ironing is reduced. Causes poor surface appearance. Therefore, the value of Mn / Fe is set to 1 ≦ Mn / Fe ≦ 2.5. If Fe is less than 0.3% as a single component, it is difficult to obtain a proper compound dispersion state, and if it exceeds 1%, the primary crystals such as (Mn, Fe) Al ₆ are added together with Mn addition. Intermetallic compounds are crystallized and formability is significantly impaired. Therefore, the amount of Fe is set to 0.3 to 1.0%. Further, since Fe and Mn are main components of the primary intermetallic compound found in this alloy system, it is necessary to regulate the total amount of these additions in order to obtain a proper dispersion state. If the amount of Fe + Mn is less than 1%, the total amount of the crystallized compound is insufficient and the ironability is poor. If it exceeds 2%, there is no problem in the ironability, but a huge primary intermetallic compound is liable to be generated and the formability is increased. The plastic deformation of the material at the time of molding does not proceed smoothly, resulting in a loss of ductility. Therefore, Fe + M
The amount of n is 1-2%. By adding Si: Si, the strength can be expected to be improved by age hardening of the Mg ₂ Si-based compound. Element required for Si promotes crystallization and precipitation of Mn similarly to Fe, and controls the amount of Mn solid solution in the aluminum matrix and the dispersion state of the Mn-based insoluble intermetallic compound. When Mn / Si is small, the size of the crystallized compound is small and ductility is generally good. However, when this value is smaller than 3, the lubricating effect at the time of ironing in DI processing is reduced, and the appearance of the can surface is poor.
If this value exceeds 4, it is difficult to control the solid solution amount of Mn to 0.16% or less, and the ductility is reduced. Therefore, the ratio of Mn / Si is in the range of 3 ≦ M / Si ≦ 4. When the amount of Si is less than 0.15%, the effect is not obtained. When the amount of Si exceeds 0.5%, although the effect of age hardening is obtained, even if the amount of Mn is adjusted, an appropriate dispersion of the crystallized compound cannot be obtained. . Therefore, the Si content is 0.15 to 0.5
% Range. Ti, B: In ordinary aluminum alloys, a small amount of Ti and B is added for refining and stabilizing ingot crystal grains.
Is added alone or together with B. Ti content is 0.0
If it is less than 05%, the effect cannot be obtained, and if it exceeds 0.2%, primary crystal TiAl ₃ is crystallized to inhibit the formability. Therefore, the Ti content is in the range of 0.005 to 0.2%.
Further, when B is added together with Ti, this effect is improved. However, when B is added, if less than 0.0001%, the effect is not obtained, and if more than 0.05%, coarse particles of TiB ₂ are mixed and formability is impaired. Therefore, the amount of B is 0.00
The range is from 0.01 to 0.05%. Zn: Addition of Zn can improve the strength by aging precipitation of Mg ₂ Zn ₃ Al _2. However, if the Zn content is less than 0.1%, there is no effect. Although this is not a problem, it is necessary to regulate the corrosion resistance to a value lower than this value because the corrosion resistance deteriorates. Therefore, the amount of Zn is 0.1 to
0.5%. Cr: Addition of Cr has a great effect on improving strength. However, when the Cr content is less than 0.05%, the effect is not obtained.
%, The formation of giant crystals added excessively and an increase in the number of crystals occur, which leads to a decrease in moldability, which is not preferable. Therefore, the amount of Cr is set to 0.05 to 0.3%. The balance of each of the above components is Al and inevitable impurities.

Next, the reasons for limiting the organization in the present invention will be described. If the number of intermetallic compounds of 5 μm or more on the plate surface is less than 100 / 0.2 mm ² , the lubricating effect and the self-cleaning effect at the time of ironing in DI processing are reduced, resulting in appearance defects such as abrasion and galling called galling. And impair the appearance of the finished can. Further, when the number of particles exceeds 200 / 0.2 mm ² , although the ironing property is good, the number of coarse particles increases, thereby impairing the ductility. Therefore, 5
100-200 intermetallic compounds of 0.2 μm or more / 0.2 m
m ² exists.

Next, the manufacturing process according to the present invention will be described. Casting: An aluminum alloy having the above-mentioned alloy composition is cast by a DC casting method (semi-continuous casting method) according to a conventional method. Soaking: Next, the ingot is subjected to preheating before hot rolling also serving as a homogenization treatment to perform hot rolling, or is subjected to heating as a homogenization treatment and then subjected to a preheating before hot rolling. Heating is performed to perform hot rolling. If the soaking temperature is less than 500 ° C or the holding time is less than 1 hour, sufficient homogenization cannot be obtained, and if it exceeds 620 ° C, the surface of the ingot may swell, so the soaking condition is a temperature of 500 to 620 ° C. It is desirable to hold for 1 hour or more. Hot rolling: After the above soaking treatment, hot rolling is performed according to a conventional method. Cold rolling (primary cold rolling): After the above-mentioned hot rolling, primary cold rolling is performed according to a conventional method. Intermediate annealing: After hot rolling and primary cold rolling, 1 ° C /
Intermediate annealing is performed at a heating / cooling rate higher than s at a temperature of 400 to 600 ° C. and a holding time of 10 minutes or less. 400 ° C
At a temperature lower than the above, solid solution of metal elements such as Cu, Mg, and Si does not progress, and therefore, improvement in strength by a solution effect cannot be expected.
On the other hand, the higher the temperature, the higher the strength due to the solution effect can be expected. Therefore, the annealing temperature is set to the ultimate temperature of 400 to 600 ° C. Further, if the cooling rate from the ultimate temperature is less than 1 ° C./s, the alloy element which has been dissolved solidly will precipitate in the cooling process,
The degree of strength improvement due to the solution effect is reduced. Therefore, the cooling rate is set to 1 ° C./s or more. Also 400-6
The time during which the product is exposed in the temperature range of 00 ° C. is within 10 minutes. If the time is longer than this, the cold rollability after annealing and the appearance of the product are impaired due to the formation of an oxide film on the surface. M
If it is only necessary to lower the amount of n solid solution, it can be easily achieved by performing annealing with a long holding time using a batch type annealing furnace. However, in order to obtain a material having a high strength after baking paint and a low strength at the time of DI forming and having good formability, an intermediate annealing by CAL, which has a small strength reduction due to the baking treatment, is used. By controlling the elements and selecting the manufacturing conditions other than the intermediate annealing, the amount of Mn solid solution can be suppressed low. Cold rolling (secondary cold rolling): After the above-mentioned annealing, secondary cold rolling (final cold rolling) with a rolling ratio of 40% or more is performed. If the rolling reduction is less than 40%, sufficient strength cannot be obtained. In addition, improvement of deep drawability can be expected by performing final annealing at about 100 to 200 ° C. as necessary.

[0010]

Next, an embodiment of the present invention will be described. Table 1 shows the composition of the alloy components used in the examples.
Table 2 shows the values of Fe, Mn / Si, and Fe + Mn.
Describing each of them, the alloy A is an inventive alloy to which Cr is added in a large amount. Alloy B is an inventive alloy containing no Cr. Alloy C is a comparative alloy in which each component is included in the claims of the present invention, but the value of (Mn / Si) is out of the range. Alloy D is a comparative alloy having a slightly lower Mn content, but each component is included in the scope of the present invention, but the value of (Fe + Mn) is out of the range. Alloy E has a low Si content in each component,
This is a comparative alloy in which the values of (Mn / Fe) and (Mn / Si) are out of range. Alloy F is a comparative alloy in which each component is included in the scope of the present invention, but the value of (Fe * Mn) is out of the range. Although the alloy G has a slightly lower Mn content, each component is included in the claims of the present invention, but is a comparative alloy in which the value of (Mn / Fe) is out of the range. Alloy H is a conventional alloy, and the values of (Mn / Fe) and (Mn / Si) are out of order.

[0012]

[Table 1]

[0013]

[Table 2]

Using each of the aluminum alloys having the chemical components shown in Table 1, a DC ingot obtained by a usual method was
After soaking at 5 ° C. for 10 hours, hot rolling was performed according to a conventional method to obtain a hot-rolled coil having a thickness of 4 mm. Nos. 1 and 3 to 9 were subjected to primary cold rolling to a sheet thickness of 0.75 mm and then subjected to intermediate annealing by CAL under the conditions that the heating / cooling rate was about 20 ° C./s and the ultimate temperature was 530.
° C and cooled immediately upon reaching. Thereafter, secondary cold rolling (final cold rolling) was performed to obtain a 0.3 mm plate, and final annealing was performed at 100 ° C. for 2 hours. No. 2 is a comparative example in which the same alloy as that of No. 1 was used, and the intermediate annealing was performed not by CAL but by a batch annealing furnace. The intermediate annealing conditions were a heating / cooling rate of 35 ° C./h and an ultimate temperature of 350 ° C.
After the temperature reached, it was kept for 2 hours and then cooled.

The tensile strength (TS: N / mm ² ), proof stress (YS: N / mm ² ), and elongation (EL) of the obtained sample after heat treatment at 200 ° C. for 20 minutes corresponding to the base plate and coating baking. :%), And the ear ratio (%) of the original plate was measured. The ear ratio was measured by deep drawing a 66 mmφ circle with a clearance of 30% using a punch of 38 mmφ and a shoulder R2.5 mm. In addition, the actual DI molding
The appearance of the can was observed, and the presence or absence of black streak-like appearance defects due to poor lubrication was evaluated as the can appearance. Further, after baking the DI can, the hole expandability of the flange portion was measured with a jig of 17R shown in FIG. 2 and evaluated as the limit flange elongation. The unit is the spread length P (mm) at break. Further, the number of crystallized substances having a size of 5 μm or more (pieces / 0.
2 mm ₂ ), and the Mn solid solution amount (%) was also measured. Table 3 shows the results.

[0015]

[Table 3]

To explain each of them, No. 1 is an invention example, and the tensile strength, proof stress and elongation of the base plate and the tensile strength, proof stress and elongation after baking are equal to those of the conventional example No. 9 and In the ratio, the invention example is as small as 3%. Further, the appearance of the DI can was not poor, and the limit flange elongation was 6 mm, which is far better than the conventional example. No. 2 is a comparative example in which the intermediate annealing of No. 1 was performed by batch annealing.
Although it is equivalent to o1, the decrease in proof stress after baking is large and the strength is insufficient. No. 3 is an invention example using alloy B and has slightly different components from No. 1 but also has better flange elongation than the conventional material. No. 4 is Mn / Si
In a comparative example using an alloy having a small value of, the number of crystallized substances of 5 μm or more is small, and the structure has many fine crystallized substances. For this reason, the limit flange elongation is equivalent to that of the invention example, but appearance failure occurs. No. 5 is a comparative example using an alloy having a small amount of Fe + Mn, and as shown in Table 3, has a structure in which the number of crystallized substances of 5 μm or more is small and the total number of crystallized substances is insufficient. For this reason, the limit flange elongation is equivalent to that of the invention example, but appearance failure occurs. No. 6 is a comparative example using an alloy having large values of Mn / Si and Mn / Fe, and the number of crystallized substances of 5 μm or more falls within the range of the present invention, but the Mn solid solution amount is as large as 0.20%. . For this reason, although the appearance defect does not occur, the limit flange elongation is as small as 4 mm, and the flange formability is not good. No. 7 is a comparative example using an alloy having a large amount of Fe + Mn. As shown in Table 3, the structure in which the number of crystallized substances exceeding 5 μm exceeds the range of the present invention and the total number of crystallized substances is excessive. It has become. Also, the amount of Mn solid solution exceeds the range of the present invention. For this reason, the elongation of the base plate is small and the formability is inferior, the ear ratio is as large as 5%, and the limit flange elongation is small, and the flange formability is extremely poor. No. 8 is a comparative example using an alloy having a small Mn / Fe. Although the amount of Mn solid solution satisfies the range of the present invention, there are many fine crystals and few crystals of 5 μm or more. Although the flange elongation is the same value as that of the invention, the appearance is poor. No. 9 is a conventional example, in which Mn / Si and Mn / Fe are large alloys. As a result, the amount of solid solution Mn increases and the critical flange elongation is small, resulting in poor flange formability.

[0017]

As described in detail above, the aluminum alloy plate manufactured according to the present invention is particularly useful as a material for a DI can body.
It is suitable for use in which a baking treatment is performed after the DI processing. In other words, since the original plate strength is not so strong, it is easy to form, and on the other hand, after baking where strength is required, it has excellent strength properties that the strength is improved by the solution effect. . Further, the ear ratio at the time of DI molding is extremely low at 3%, which is an excellent material in terms of ear ratio. Furthermore, the limit flange elongation is 6mm
It is particularly excellent in flange formability. Also, appearance defects such as black streaks do not occur. Therefore, according to the present invention, it is possible to easily and effectively produce an aluminum alloy plate for a DI can which is excellent in strength and excellent in formability after paint baking, particularly excellent in flange formability.

[Brief description of the drawings]

FIG. 1 is a graph showing the relationship between the Mn solid solution amount and the limit flange elongation.

FIG. 2 is a cross-sectional view illustrating a process of expanding a hole in a flange portion using a jig according to the embodiment of the present invention.

[Explanation of symbols]

 10 Can body 11 Hole expanding jig P Limit flange elongation

────────────────────────────────────────────────── ─── Continued on the front page (51) Int.Cl. ⁷ Identification code FI C22F 1/00 673 C22F 1/00 673 686 686A 691 691A 693 693A 693B 1/04 1/04 C (58) .Cl. ⁷ , DB name) C22C 21/00-21/18 C22F 1/04-1/057

Claims (2)

(57) [Claims] 1. Mg: 0.5% by weight (hereinafter the same).
To 2.0%, Mn: 0.6 to 1.4%, Cu: 0.05
0.5%, Fe: 0.3 to 1.0%, Si: 0.15
~ 0.5%, Ti: 0.0 for finer structure and stabilization
0.05 to 0.2% alone or B: 0.0001 to
0.05%, 1 ≦ Mn / Fe ≦ 2.5,
3 ≦ Mn / Si ≦ 4, 1% ≦ Fe + Mn ≦ 2%, Cr: 0.05-0.3%, Zn: 0.
1 to 0.5%, and the balance consists of Al and unavoidable impurities.
100-200 intermetallic compounds of 0.2 μm or more / 0.2 m
An aluminum alloy sheet for a DI can excellent in formability, particularly in flange formability after DI forming, characterized in that m ^{2 is} present and the Mn solid solution amount is 0.16% or less. 2. An ingot of an aluminum alloy having the chemical composition according to claim 1 is subjected to soaking, hot rolling is performed, and then cold rolling is performed. Annealing is performed at a cooling rate of 400 to 600 ° C. at an reaching temperature of 10 minutes or less, and then cold rolling is performed at a rolling reduction of 40% or more, and 100 to 200 intermetallic compounds of 5 μm or more on the sheet surface are obtained. /0.2mm ² exists, M
A method for producing an aluminum alloy sheet for a DI can having excellent moldability, particularly excellent in flange formability after DI molding, characterized in that the amount of n solid solution is 0.16% or less.