JPH05331588A - Aluminum alloy sheet for forming excellent in flange formability and its production - Google Patents

Abstract

PURPOSE:To produce an Al alloy sheet for forming excellent in flange formability by limiting the components, mainly, of Mn, Fe, and Si and regulating the state of dispersion of intermetallic compound and the amount of solid- solution Mn, respectively. CONSTITUTION:An Al alloy sheet which has a composition consisting of, by weight, 0.5-2% Mg, 0.6-1.4% Mn, 0.3-1% Fe, 0.15-0.5% Si, 0.005-0.2% Ti as a component for refining and stabilizing structure, independently or in combination with 0.0001-0.05% B, further one or more kinds among 0.05-0.5% Cu, 0.05-0.3% Cr, and 0.1-0.5% Zn, and the balance Al with inevitable impurities and satisfying the conditions of 1<=Mn/Fe<=2.5, 3<=Mn/Si<=4, and 1%<=Fe+Mn<=2% and where intermetallic compound of >=5mu grain size exists in the sheet surface by (100 to 200)pieces/0.2mm<2> and the amount of solid-solution Mn is regulated to <=0.16% is prepared. By this method, the Al alloy sheet for forming excellent in flange formability after DI forming can be obtained.

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 moldability and excellent in moldability after baking after molding, and a method for producing the aluminum hard plate. The present invention relates to an Al-Mg-Mn-based aluminum alloy hard plate having excellent flange formability after paint baking, which is suitable for a can body of a two-piece aluminum can (DI can), and a method for producing the same.

[0002]

2. Description of the Related Art In recent years, aluminum alloy sheets used as cans have been made thinner and have higher strength. This is due to economic demands such as cost reduction by using a stronger thin plate. JIS
Since the 3004 alloy hard plate has relatively good formability even when cold rolled with a high rolling ratio to increase the strength, it has been conventionally used for such can body materials. It was This JIS 3004 alloy hard plate is often manufactured by homogenizing, then hot rolling according to a conventional method, and then performing intermediate annealing with or without cold rolling. On the other hand, with the widespread use of continuous annealing furnaces (CAL) in recent years, it has become possible to carry out intermediate annealing of reaching high temperature and rapid cooling, and as a result, the production of can body materials with high strength utilizing the solutionizing effect becomes the mainstream. It's starting. According to this method, since the decrease in strength after paint baking is small, the strength during DI molding does not have to be as high as that of the conventional batch type intermediate annealed material, and the DI moldability becomes good.

[0003]

As described above, the thickness of the can body is being reduced, but DI molding was performed in proportion to the reduction of the thickness of the base plate before molding. The side wall of the later can also becomes thinner. Conventionally, the flange forming part of the side wall has a thickness of 2
What has been about 00 μm is now as thin as about 150 μm, and there is a tendency for it to be even thinner. However, if the plate thickness of the flange forming portion becomes thin, the ductility decreases, the crack susceptibility during forming increases, and the flange formability deteriorates.

The present invention is based on the conventionally used JIS30.
Based on an alloy system different from 04 alloy, ear ratio, strength,
Properties such as DI moldability are equal to or better than conventional materials,
Moreover, it is an object of the present invention to provide a material suitable for a can body which has excellent flange formability and seaming formability.

[0005]

[Means for Solving the Problems] In order to achieve the above-mentioned object, the inventors of the present invention have comprehensively studied comprehensively on chemical component adjustment, structure, manufacturing conditions, etc.
It has been found that the above object can be achieved by limiting the components of Fe and Si so as to obtain an appropriate intermetallic compound dispersion state and an appropriate Mn solid solution amount.

That is, according to the present invention, the weight% of Mg is 0.5 to 2.0% and the Mn is 0.6 to 1.
4%, Fe: 0.3 to 1.0%, Si: 0.15 to 0.
5%, Ti: 0.005 to refine and stabilize the structure
0.20% alone or B: 0.0001 to 0.0
Included with 5%, 1 ≦ Mn / Fe ≦ 2.5, 3 ≦ M
n / Si ≦ 4, 1% ≦ Fe + Mn ≦ 2% are satisfied, and further Cu: 0.05 to 0.5%, Cr: 0.05.
.About.0.3%, Zn: 0.1 to 0.5% of one or more, and the balance consisting of Al and unavoidable impurities. ~ 200 pieces / 0.2 mm ² exist, and the Mn solid solution amount is 0.16% or less.
It is an aluminum alloy plate for forming which is excellent in flange formability after forming. Further, according to claim 2, Mg: 0.5 to 2.0% and Mn: 0.6 to 1.% by weight. Four
%, Fe: 0.3 to 1.0%, Si: 0.15 to 0.5
%, Ti: 0.005 to refine and stabilize the structure
0.20% alone or B: 0.0001 to 0.0
Included with 5%, 1 ≦ Mn / Fe ≦ 2.5, 3 ≦ M
n / Si ≦ 4, 1% ≦ Fe + Mn ≦ 2% are satisfied, and further Cu: 0.05 to 0.5%, Cr: 0.05.
~ 0.3%, Zn: 0.1 to 0.5% of one or more of 0.1%, and the balance of Al and unavoidable impurities in the aluminum alloy ingot is soaked according to a conventional method. After that, hot rolling is performed, and then, as it is or after cooling or after cold rolling, annealing is performed at a heating / cooling rate of 1 ° C./s or more at an ultimate temperature of 400 to 600 ° C. for a holding time of 10 minutes or less. Cold rolling at a rolling rate of 40% or more, 100 to 200 intermetallic compounds of 5 μm or more / 0.2 mm ^{2 on} the plate surface, and a Mn solid solution amount of 0.16% or less. Moldability characterized by that D
I is a method for producing an aluminum alloy sheet for forming which is excellent in flange formability after forming.

[0007]

The present invention will be described in more detail below. First, the reasons for limiting the chemical components in the present invention will be described. Mg: Mg is expected to improve strength by aging precipitation of Mg ₂ Si or Al-Cu-Mg by coexistence with Si / Cu. In the case of intermediate annealing having a solution treatment effect as in the present invention, especially after coating baking, It is effective in suppressing the decrease in strength. Further, Mg alone is effective in improving strength by strengthening the solid solution. As described above, it is an essential element for improving strength, but if the Mg content is less than 0.5%, its effect is small and sufficient strength cannot be obtained. Although there is no problem in point, workability is likely to be hardened, so that redrawability and ironing property are deteriorated. Therefore, M
The amount of g is 0.5 to 2.0%. Mn: Mn is an element that contributes to the improvement of strength and is effective in improving the formability. Mn is particularly important for can body material, which is the purpose of the present invention, for ironing. Emulsion type lubricants are usually used in the ironing of aluminum alloy sheets. However, even if the structure has the same level of strength and a small number and amount of Mn-based crystallized substances, the emulsion type lubricant alone lacks the lubrication ability, and the appearance defect such as scratches and seizure called galling is poor. Occurs. This phenomenon is affected by the size, amount, and type of crystallized substances, and it is essential to add an appropriately selected Mn amount. Although solute Mn greatly contributes to the improvement of strength, it does not contribute to strength like Mg to improve ductility, but has an action of making the material brittle. FIG. 1 shows the influence of Mn solid solution amount on the ductility by measuring the limit flange elongation as an evaluation of the ductility. Mn
It can be seen that when the solid solution amount of is up to 0.16%, the ductility is not reduced, but when it exceeds 0.16%, the ductility is reduced with an increase in the solid solution amount. Therefore, the Mn solid solution amount is 0.1
6% or less. If the Mn content is less than 0.6%, Mn
The solid lubricating effect of the compound cannot be obtained, but 1.4
If it exceeds%, it will be mixed with Fe, which will be described later, (Mn, F
e) The primary crystal giant intermetallic compound of Al ₆ crystallizes, and the formability is significantly impaired. Further, the solid solution amount of Mn increases as the added amount of Mn increases, but the solid solution amount of Mn can be adjusted by the added amount of Fe.Si etc. even if the added amount of Mn is large. However, if the amount of Mn added exceeds 1.4%, Si
-It is difficult to suppress the amount of Mn solid solution depending on the amount of Fe.
Therefore, the Mn content is 0.6 to 1.4%. Fe: Fe is an element necessary for promoting crystallization and precipitation of Mn, and controlling the solid solution amount of Mn in the aluminum matrix and the dispersed state of the Mn-based insoluble intermetallic compound. The necessary condition for obtaining the proper state is the addition of Fe according to the amount of Mn added. If Mn / Fe is more than 2.5, the amount of Mn solid solution increases and the ductility deteriorates. When the value of Mn / Fe becomes smaller, the crystallized compound becomes finer and the ductility is generally improved. However, when the value is less than 1, the crystallized product size becomes too small and the lubrication effect at the time of ironing is reduced, resulting in a can. Causes poor surface appearance. Therefore, the value of Mn / Fe is 1 ≦ Mn / Fe ≦ 2.5. Further, 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%, it is combined with Mn addition to form a large primary crystal such as (Mn, Fe) Al _6. The intermetallic compound crystallizes and the formability is significantly impaired. Therefore, the amount of Fe is set to 0.3 to 1.0%. Furthermore, since Fe and Mn are the main components of the primary crystal intermetallic compound found in this alloy system, it is necessary to regulate the total addition amount of these in order to obtain a proper dispersed state. If the Fe + Mn amount is less than 1%, the total amount of crystallized compounds is insufficient and the ironing property is inferior. If it exceeds 2%, there is no problem in the ironing property, but a huge primary crystal intermetallic compound is likely to be generated and formability is increased. The plastic deformation of the material at the time of molding does not go smoothly, resulting in a loss of ductility. Therefore, Fe + M
The amount of n is 1-2%. Si: The addition of Si can be expected to improve the strength of the Mg ₂ Si-based compound due to age hardening. However, in the present invention, the crystallized substance is in an appropriate dispersed state and the Mn solid solution amount is in an appropriate state. Is an element necessary for. Si, like Fe, promotes crystallization and precipitation of Mn, and controls the amount of Mn solid solution in the aluminum matrix and the dispersed state of the Mn-based insoluble intermetallic compound. When Mn / Si becomes smaller, the size of the crystallized compound becomes finer and ductility is generally improved, but when this value is smaller than 3, the lubricating effect at the time of ironing forming in DI processing is deteriorated and the appearance of the can surface is deteriorated.
Further, if this value exceeds 4, it becomes difficult to control the solid solution amount of Mn to 0.16% or less, and ductility decreases. Therefore, the ratio of Mn / Si should be in the range of 3 ≦ Mn / Si ≦ 4. Further, if the Si content is less than 0.15%, the effect is not obtained, and if it exceeds 0.5%, the age hardening is effective, but Mn Even if the addition amount is adjusted, an appropriate dispersion of the crystallized compound cannot be obtained. Therefore, the amount of Si is 0.15 to 0.5
The range is%. Ti, B: In ordinary aluminum alloys, a small amount of Ti and B is added for refining and stabilizing the ingot crystal grains. In the present invention, a small amount of Ti alone or B is also used. Added with. Ti amount is 0.00
If it is less than 5%, the effect cannot be obtained, and if it exceeds 0.2%, primary crystal TiAl ₃ crystallizes and hinders 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, in the case of adding B, if it is less than 0.0001%, there is no effect, and if it exceeds 0.05%, coarse particles of TiB ₂ are mixed and the formability is impaired. Therefore, the amount of B is 0.000
The range is 1 to 0.05%. Cu: In the present invention, strength improvement due to the solution treatment effect of Cu can be expected. That is, Al-Cu-M during baking treatment
It is an element that contributes to strength improvement by utilizing the age hardening that occurs in the precipitation process of g-based precipitates. If the Cu content is less than 0.05%, the effect cannot be obtained. On the other hand, if the Cu content is more than 0.5%, age hardening is easily obtained, but it becomes too hard and hinders moldability. Therefore, the Cu amount is 0.05 to 0.
The range is 5%. The addition of Zn: Zn is expected to improve the strength by aging precipitation of Mg ₂ Zn ₃ Al ₂ , but if the Zn content is less than 0.1%, this effect is not obtained, and if it is added in excess of 0.5%, the strength is However, there is no problem, but since corrosion resistance is deteriorated, it is necessary to regulate below this value. Therefore, the Zn content is 0.1 to
0.5%. Cr: Addition of Cr has a great effect on the strength improvement. However, if the amount of Cr is less than 0.05%, the effect is not obtained and 0.3
If it is added excessively in excess of%, the formation of huge crystallized substances and the increase in the number of crystallized substances occur, resulting in a decrease in moldability, which is not preferable. Therefore, the Cr content is 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 of the present invention will be described. When the intermetallic compound of 5 μm or more on the plate surface is less than 100 / 0.2 mm ² , the lubrication effect and the self-cleaning effect at the time of ironing in DI processing are reduced, so that appearance defects such as scratches and seizure called galling occur. However, the appearance of the finished can is damaged. On the other hand, if it exceeds 200 particles / 0.2 mm ² , the ironing property is good, but the ductility is impaired because the number of coarse particles increases. Therefore, 5 on the plate surface
100 to 200 intermetallic compounds with a size of μm or more / 0.2 m
m ² exists.

Next, the manufacturing process in the present invention will be described. Casting: An aluminum alloy having the above alloy composition is cast by a DC casting method (semi-continuous casting method) according to a conventional method. Soaking: Then, the ingot is preheated before hot rolling which also serves as homogenization treatment to perform hot rolling, or is heated as homogenization treatment and then preparatory before hot rolling. It is heated and hot rolled. 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, swelling may occur on the surface of the ingot, so the soaking condition is a temperature of 500 to 620 ° C. It is desirable to maintain the temperature for 1 hour or more. Hot rolling: Hot rolling is performed according to a conventional method after the soaking. Intermediate annealing: 1 ° C. as it is after hot rolling, after hot rolling and then cooling, or after hot rolling and cold rolling.
The intermediate annealing is performed at a heating / cooling rate faster than / s at an ultimate temperature of 400 to 600 ° C. for a holding time of 10 minutes or less. 400
If the temperature is lower than ℃, solid solution of metal elements such as Cu, Mg and Si does not proceed, and therefore strength improvement due to solution effect cannot be expected. On the other hand, the higher the temperature, the more the strength can be expected to be improved by the solutionizing effect. However, at a temperature higher than 600 ° C., eutectic melting causes inconvenience in production and poor appearance of the product. 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 elements that have been solid-dissolved will precipitate during the cooling process, and the degree of strength improvement due to the solution treatment effect will decrease.
Therefore, the cooling rate is 1 ° C./s or more. Again 40
The time for which the product is exposed in the temperature range of 0 to 600 ° C is 10 minutes or less. If the time is longer than this, an oxide film is formed on the surface, which impairs the cold rollability after the annealing and the appearance of the product. If only the amount of Mn solid solution is reduced, it can be easily achieved by performing annealing with a long holding time in a batch type annealing furnace. However, in the present invention, in order to obtain a material having high strength after coating baking and low strength at the time of DI molding and good moldability, intermediate annealing by CAL that causes little strength reduction due to coating baking treatment is adopted, and the alloy composition By controlling the elements and selecting manufacturing conditions other than intermediate annealing, it was possible to suppress the amount of Mn solid solution to a low level. Cold rolling: After the above annealing, cold rolling with a rolling ratio of 40% or more is performed. If the rolling ratio 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. if necessary.

[0010]

EXAMPLES Next, examples of the present invention will be described. Table 1 shows the composition of the alloy components used in the examples, and Mn /
The values of Fe, Mn / Si and Fe + Mn are shown in Table 2.
Explaining each of them, alloy A is an invention alloy in which Cr is added in a large amount. Alloy B is an invention alloy containing no Cr. Alloy C is a comparative alloy in which each component falls within the scope of the claims of the present invention, but the value of (Mn / Si) is deviated. Alloy D is a comparative alloy having a slightly low Mn content, but each component is included in the scope of the claims of the present invention, but the value of (Fe + Mn) is deviated. Alloy E has low Si content in each component,
Further, it is a comparative alloy in which the values of (Mn / Fe) and (Mn / Si) are deviated. Alloy F is a comparative alloy in which each component falls within the scope of the claims of the present invention, but the value of (Fe * Mn) is deviated. Alloy G is a comparative alloy having a slightly low Mn content, but each component is included in the scope of the claims of the present invention, but the value of (Mn / Fe) deviates. Alloy H is a conventional alloy, and the values of (Mn / Fe) and (Mn / Si) are deviated.

[0012]

[Table 1]

[0013]

[Table 2]

Using each aluminum alloy having the chemical composition shown in Table 1, 60 DC ingots obtained by a conventional method were used.
Soaking was performed at 5 ° C. for 10 hours, and then 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 obtained by cold rolling to a plate thickness of 0.75 mm and then performing intermediate annealing by CAL under the conditions of a heating / cooling rate of about 20 ° C./s and an ultimate temperature of 530 ° C. , It cooled immediately after reaching. Then, cold rolling was performed to obtain a 0.3 mm plate, and final annealing was performed at 100 ° C. for 2 hours. No. 2 uses the same alloy as No. 1 and is a comparative example in which the intermediate annealing is performed by a batch annealing furnace instead of CAL. The intermediate annealing condition is that the heating / cooling rate is about 35 ° C /
h, the ultimate temperature was 350 ° C., the temperature was maintained for 2 hours and then cooled.

The tensile strength (TS: N / mm ² ), proof stress (YS: N / mm ² ), and elongation (EL) of each of the obtained samples after heat treatment at 200 ° C. for 20 minutes corresponding to the base plate and coating baking :%), And the ear ratio (%) of the base plate was measured. The ear rate was measured by deep-drawing a 66 mmφ circle with a clearance of 30% using a punch having a 38 mmφ and a shoulder R2.5 mm. In addition, by performing 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 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 of 5 μm or more (number / 0.
2 mm ₂ ) was also measured, and the Mn solid solution amount (%) was also measured. The results are shown in Table 3.

[0015]

[Table 3]

Explaining 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 equivalent to those of the conventional example No. 9, and the ear In terms of the rate, the invention example is as small as 3%. In addition, the appearance of the DI can was not deteriorated, and the limit flange elongation was 6 mm, which is far superior to the conventional example. No. 2 is a comparative example in which the intermediate annealing of No. 1 is batch annealing, but the ear ratio and the limit flange elongation are N.
Although it is equivalent to o1, the yield strength after baking is large and the strength is insufficient. No. 3 is an example of the invention using alloy B, and although the composition is slightly different from No. 1, similarly, the flange elongation is better than the conventional material. No4 is Mn / Si
In a comparative example using an alloy having a small value of, the structure has a small number of crystallized substances of 5 μm or more and many fine crystallized substances. Therefore, although the limit flange elongation is the same as that of the invention example, the appearance defect occurs. No. 5 is a comparative example using an alloy with a small amount of Fe + Mn, and as shown in Table 3, the number of crystallized substances of 5 μm or more is small, and the total number of crystallized substances is insufficient. Therefore, although the limit flange elongation is the same as that of the invention example, the appearance defect occurs. No. 6 is a comparative example using an alloy having a large value of Mn / Si and Mn / Fe, and the number of crystallized substances of 5 μm or more is 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, and as shown in Table 3, the number of crystallized substances of 5 μm or more exceeds the range of the present invention and the total number of crystallized substances is excessive. Has become. The amount of Mn solid solution also exceeds the range of the present invention. For this reason, the elongation of the base plate is small and the moldability is inferior, and the selvedge ratio is as large as 5%, and the limiting flange elongation is small, resulting in extremely poor flange moldability. No. 8 is a comparative example using an alloy having a small Mn / Fe. Although the Mn solid solution amount satisfies the range of the present invention, there are many fine crystallized substances and there are few crystallized substances of 5 μm or more. The flange elongation is the same value as that of the invention example, but the appearance defect occurs. No. 9 is a conventional example, and is an alloy having a large Mn / Si and Mn / Fe. For this reason, the amount of solid solution of Mn is large, the limit flange elongation is small, and the flange formability is poor.

[0017]

As described above in detail, the aluminum alloy sheet produced according to the present invention is particularly suitable for applications such as a can material which is subjected to DI baking and then baking treatment. That is, since the base plate strength is not so strong, it can be easily formed and processed. On the other hand, after baking which requires strength, the strength is improved by the solution treatment effect, which is excellent in strength. .. Further, the ear rate at DI molding is as low as 3%, which is an excellent material in terms of ear rate.
Further, the limit flange elongation is 6 mm, which is particularly excellent in flange formability. In addition, the appearance defects such as black streaks do not occur. Therefore, according to the present invention, it is possible to easily and efficiently manufacture an aluminum alloy sheet which is excellent in strength and is excellent in formability after baking for coating, especially in flange formability.

[Brief description of drawings]

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

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

[Explanation of symbols]

 10 Can barrel 11 Hole expanding jig P Limit flange extension

Claims (2)

[Claims] 1. In weight% (hereinafter the same), Mg: 0.5
~ 2%, Mn: 0.6-1.4%, Fe: 0.3-1
%, Si: 0.15 to 0.5%, Ti: 0.005 to 0.2% alone or together with B: 0.0001 to 0.05% for microstructuring / stabilization, 1 ≦ M
n / Fe ≦ 2.5, 3 ≦ Mn / Si ≦ 4, 1% ≦ Fe +
The condition of Mn ≦ 2% is satisfied, and further Cu: 0.05 to
0.5%, Cr: 0.05 to 0.3%, Zn: 0.1
One or more of 0.5% is contained, the balance consisting of Al and unavoidable impurities.
100 to 200 intermetallic compounds with a size of μm or more / 0.2 m
An aluminum alloy plate for forming, which is excellent in formability, particularly flange formability after DI forming, characterized in that m ^{2 is} present and the amount of Mn solid solution is 0.16% or less. 2. The ingot of the aluminum alloy having the chemical composition according to claim 1 is subjected to soaking according to a conventional method and then hot-rolled, and then, as it is or after cooling or cold-rolling, 1 ° C. 400 at a heating / cooling rate of over s / s
Annealing is performed at a reached temperature of up to 600 ° C for a holding time of 10 minutes or less, and then cold rolling is performed at a rolling rate of 40% or more, and an intermetallic compound of 5 µm or more on the plate surface is 100 to 20
0 pieces / 0.2 mm ² are present and the amount of Mn solid solution is 0.16% or less, and the method for producing an aluminum alloy sheet for forming, which has excellent formability, particularly flange formability after DI forming. ..