JP2003277870A - Aluminum alloy sheet having excellent bending workability and hardenability in coating/baking, and production method thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an aluminum alloy sheet which has excellent bending workability capable of flatting hem working, has excellent hardenability in coating/baking, and further has excellent corrosion resistance, and to provide a production method thereof. <P>SOLUTION: The aluminum alloy sheet comprises 0.5 to 2.0% Si and 0.2 to 1.5% Mg, and satisfying 0.7Si%+Mg%≤2.2%, and the balance Al with impurities. Alternatively, the aluminum alloy sheet comprises one or more kinds of metals selected from ≤0.5% Zn, ≤1.0% Cu, ≤1.0% Mn, ≤0.3% Cr, ≤0.2% V, ≤0.2% Zr, ≤0.1% Ti and ≤50 ppm B in addition to the composition of the above aluminum alloy. The aluminum alloy sheet has the characteristics that the intensity ratio in the Cube orientation of the texture is ≥20. A cast ingot is homogenized at ≥450°C, is thereafter cooled to a prescribed temperature of <350°C at a cooling rate of ≥100°C/h, and is hot-rolled at the same prescribed temperature. The sheet is further cold-rolled, and is subsequently solution-treated and quenched at ≥500°C, so that the aluminum alloy sheet is produced. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an aluminum alloy sheet which is excellent in bending workability and paint bake hardenability and is particularly suitable for an automobile outer panel, and a method for producing the same.

[0002]

[Background Art] As a measure against global warming, which is a global environmental problem,
In order to improve the fuel efficiency of automobiles, the material for automobile parts is used by replacing the conventional steel plate with an aluminum alloy plate for the purpose of weight reduction. Among them, various aluminum alloys have been developed and put to practical use for automobile outer panels.

For automobile outer panels, 1) formability, 2)
Freezing of the shape (the shape of the press die should appear accurately during pressing), 3) Dent resistance, 4) Corrosion resistance 5) Product surface quality, etc. are required. Among these characteristics, the shape fixability becomes better as the yield strength becomes smaller, whereas the dent resistance becomes better as the yield strength becomes larger, and both sides are in conflict with each other. To solve these conflicting issues,
In the case of Al-Mg-Si based aluminum alloys, a method of performing press forming at a stage where the proof strength is excellent and low yielding strength, and then hardening during coating baking to increase the yield strength and improve the dent resistance Has been carried out (JP-A-4-147951, JP-A-5-247610, JP-A-5-279822,
JP-A-6-17208).

Corrosion resistance and product surface quality are strictly required for the outer plate, especially in the bonnet outer, after press working, rough skin and ridging marks (long streaky defects in the rolling direction caused by plastic working) occur. May be of poor quality. Such product quality is solved by adjusting and controlling chemical components and manufacturing conditions. For example, in order to suppress ridging marks, after homogenizing at a temperature of 500 ° C. or higher, 450-350. It has been proposed to prevent the formation of coarse precipitates by cooling to ℃ and starting hot rolling in this temperature range (JP-A-7-228956).
However, in this method, precipitation and agglomeration of Mg ₂ Si may occur, so that solution treatment is required at high temperature for a long time, and there is a problem in that efficiency is reduced industrially.

Further, it is desired that the outer material is hem-processed when it is assembled with the inner, so that a flat hem is possible.
Bending workability is inferior to that of steel plate, and further, the conventional 6000 series aluminum alloy is inferior to the 5000 series aluminum alloy in bending workability, and there is a problem that flat hem cannot be formed in a portion having a large degree of press working. Furthermore, bending in flat hem or more (machining with an inner bending radius of less than 0.5 mm) is desired in areas where the forming shape is strict or where dimensional accuracy is strict.

The inventors of the present invention have found that the 6000 series (Al-Mg-S
As a result of repeated tests and examinations regarding the factors that affect the formability of the (i) aluminum alloy material, in particular, the bending workability, the bending workability shows that the Cube orientation of the texture is {100} <001>.
It has been found that a texture having a high degree of integration of Cube orientations is required to improve bending workability, which is related to the strength ratio (random ratio) of 6000 series aluminum alloy. Is the main additive element of
We have found that it is important to optimize the amounts of Si and Mg and to optimize the manufacturing process, especially to control the cooling rate after the homogenization treatment properly.

[0007]

DISCLOSURE OF THE INVENTION The present invention has been made in order to solve the above-mentioned conventional problems in the case of applying a 6000 series (Al-Mg-Si series) aluminum alloy plate as an automobile outer plate. It was made as a result of further tests and examinations based on the above, and the purpose is to have excellent bending workability capable of flat hem processing and to solve the problem of dent resistance. An object of the present invention is to provide an aluminum alloy plate having curability and excellent corrosion resistance and a method for producing the same.

[0008]

An aluminum alloy sheet excellent in bending workability and paint bake hardenability according to claim 1 of the present invention for achieving the above object is formed of Al-Mg-S.
A rolled plate of an i-based aluminum alloy, characterized in that the formed texture has a Cube orientation strength ratio of 20 or more.

The aluminum alloy plate excellent in bending workability and paint bake hardenability according to claim 2 is the aluminum alloy plate according to claim 1, wherein the Al--Mg--Si based aluminum alloy is Si: 0.
5% to 2.0% (mass%, the same below), Mg: 0.2 to 1.5
%, 0.7Si% + Mg% ≤ 2.2%, balance Al
And an aluminum alloy containing impurities.

The aluminum alloy plate excellent in bending workability and paint bake hardenability according to claim 3 is the aluminum alloy plate according to claim 1 or 2, further comprising: Zn: 0.5
% Or less is contained.

An aluminum alloy plate excellent in bending workability and paint bake hardenability according to claim 4 is claimed in claims 1 to 3.
In either case, the aluminum alloy plate is further Cu
: 1.0% or less is contained.

An aluminum alloy plate excellent in bending workability and paint bake hardenability according to claim 5 is provided by claims 1 to 4.
In any of the above, the aluminum alloy plate is further M
n: 1.0% or less, Cr: 0.3% or less, V: 0.2% or less,
Zr: It is characterized by containing one or more of 0.2% or less.

An aluminum alloy plate excellent in bending workability and paint bake hardenability according to claim 6 is provided by claim 1.
In any of the
i: 0.1% or less, B: 50ppm or less, at least 1
It is characterized by containing a seed.

A method for producing an aluminum alloy sheet excellent in bending workability and bake hardenability according to claim 7 of the present invention for achieving the object of the present invention is the aluminum alloy according to any one of claims 1 to 6. A method for producing a plate, which comprises homogenizing an ingot of an aluminum alloy having the composition according to any one of claims 1 to 6 at a temperature of 450 ° C or higher,
Cooling to a predetermined temperature of less than 350 ° C at a cooling rate of ° C / h or more, hot rolling at the predetermined temperature, cold rolling, and then solution treatment and quenching at a temperature of 450 ° C or more. Characterize.

A method for producing an aluminum alloy sheet excellent in bending workability and bake hardenability according to claim 8 is the method for producing an aluminum alloy sheet according to any one of claims 1 to 6, wherein The ingot of the aluminum alloy having the composition according to any one of 6 above is homogenized at a temperature of 450 ° C or higher, cooled to a temperature of less than 350 ° C at a cooling rate of 100 ° C / h or more, and further 300 to 500 ° C. It is characterized in that hot rolling is performed by reheating to the temperature of 2 to start rolling, further cold rolling is performed, and then solution treatment and quenching are performed at a temperature of 450 ° C. or higher.

A method for producing an aluminum alloy sheet excellent in bending workability and bake hardenability according to claim 9 is the method for producing an aluminum alloy sheet according to any one of claims 1 to 6, wherein The aluminum alloy ingot having the composition according to any of 6 above is homogenized at a temperature of 450 ° C or higher, cooled to a temperature of less than 350 ° C at a cooling rate of 100 ° C / h or more, and further cooled to room temperature. , Then 300-50
It is characterized in that hot rolling is performed to reheat to a temperature of 0 ° C. to start rolling, cold rolling is further performed, and then solution treatment and quenching are performed at a temperature of 450 ° C. or higher.

According to a tenth aspect of the present invention, in the method for producing an aluminum alloy excellent in bending workability and bake hardenability, the hot rolling finish temperature is 300.
It is characterized in that the temperature is below ℃.

A method for producing an aluminum alloy sheet excellent in bending workability and bake hardenability according to claim 11 is the method according to any one of claims 7 to 10, which is 120 ° C. after solution treatment.
It is characterized in that quenching is performed at a cooling rate of 5 ° C / s or more, and heat treatment is performed within 60 minutes after quenching at a temperature of 40 to 120 ° C for 50 hours or less.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION The meanings and reasons for limitation of alloy components in the Al-Mg-Si alloy sheet of the present invention will be described. Si: Necessary for obtaining strength and high BH property,
It functions to form Mg-Si compounds and increase strength.
The preferable content is in the range of 0.5 to 2.0%. If the content is less than 0.5%, sufficient strength may not be obtained by heating during coating baking, and the formability may be deteriorated. Yield strength is high, moldability and shape fixability are poor, and corrosion resistance after coating is also deteriorated. A more preferable content is in the range of 0.8 to 1.2%.

Like Mg: Si, it functions to increase strength. The preferred content is in the range of 0.2-1.5%, 0.2
If it is less than%, sufficient strength cannot be obtained by heating during baking of the coating. On the other hand, if it exceeds 1.5%, the yield strength after solution treatment or after completion of the final heat treatment is high and the formability and shape fixability are poor. A more preferable content is in the range of 0.3 to 0.7%.

In the present invention, the amount of Si as the main component and M
It is important to set the relationship with the g amount to be 0.7Si% + Mg% ≦ 2.2%. With the content of Mg and Si satisfying this relationship, a texture is formed after the solution treatment, and the Cube of the texture is formed.
The strength ratio of the azimuth is increased, proper strength is obtained, and bending workability is improved. A more preferable relationship between the amounts of Mg and Si is 0.7Si% + Mg% ≦ 1.8%.

Zn: Improves zinc phosphate treatability during surface treatment, but the preferable content is in the range of 0.5% or less, and if it exceeds 0.5%, corrosion resistance deteriorates. More preferably, it is added within the range of 0.1 to 0.3%.

Cu: Improves strength and formability. The preferable content is 1.0% or less, and if it exceeds 0.1%, the corrosion resistance is deteriorated. More preferably, it is added in the range of 0.3 to 0.8%.

Mn, Cr, V, Zr: Improves strength and makes crystal grains finer to prevent roughening of the surface during molding. The preferred contents are Mn 0.3% or less and Cr 0.3%
Below V0.2% and Zr0.15% range,
If the respective upper limits are exceeded, a coarse intermetallic compound is produced and the formability deteriorates. More preferably, Mn: 0.05-
0.15%, Cr: 0.05 to 0.15%, V: 0.05 to 0.15%, Zr: 0.
Add in the range of 05-0.12%.

Ti, B: The cast structure is refined to improve the formability. The preferred content is Ti 0.1% or less, B50
The content is in the range of ppm or less, and when the content of each exceeds the upper limit, coarse intermetallic compounds increase and the formability decreases.
As other impurities, it is desirable to regulate Fe to 0.5% or less, preferably 0.3% or less.

Next, the manufacturing process of the aluminum alloy plate of the present invention will be described. Homogenization condition: It is necessary to perform at a temperature of 450 ° C or higher. If the heating temperature is lower than 450 ° C, the ingot ingot segregation and homogenization are insufficient, and the solid solution of the Mg ₂ Si component that contributes to the strength is achieved. May be insufficient, resulting in poor moldability.

Cooling after homogenization treatment: Cooling rate is 100 ° C./h
As described above, more preferable characteristics can be obtained by cooling at a cooling rate of 300 ° C./h or more. Since large-scale equipment is required to increase the cooling rate, it is desirable to control at 300-1000 ° C / h for practical use. If the cooling rate is slow, Mg-Si compounds will precipitate and agglomerate. With the conventional cooling method, the cooling rate is 30 ° C for large slabs.
/ h, and at such a low cooling rate, the Mg-Si 2 -based compound is precipitated and agglomerated and coarsened during cooling, and a material having a large Cube orientation cannot be obtained. If it becomes a coarse precipitate, recrystallization during solution treatment is suppressed, and the degree of integration of Cube orientation becomes low.

For the cooling after the homogenization treatment, it is necessary to cool to a temperature range of less than 350 ° C. at a cooling rate of 100 ° C./° C. or higher, preferably 300 ° C./° C. or higher, and even in a partial location of 350 ° C. or higher If there is, it affects the characteristics. Therefore, the total is 250
It is more preferable to cool at the above rate until the temperature becomes not higher than 0 ° C. The method for cooling the homogenized ingot is not particularly limited as long as it can obtain the required cooling rate, such as water cooling, fan cooling, mist cooling, and heat sink contact.

The starting temperature of cooling does not necessarily have to be the homogenizing treatment temperature, and even after gradually cooling to a temperature at which precipitation does not occur remarkably, cooling at a cooling rate of 100 ° C./h or more is started. The same effect can be obtained. For example, 500 ° C
When the homogenization treatment is performed at the above temperature, cooling to 500 ° C may be slow.

Hot rolling: In hot rolling, the ingot is cooled from the homogenization treatment temperature to a predetermined temperature of less than 350 ° C. and started at the predetermined temperature. Alternatively, cool to a temperature below 350 ° C,
It is also possible to reheat to a temperature of 350-500 ° C to start hot rolling. The hot rolling may be started by cooling to a temperature of less than 300 ° C, further cooling to room temperature, and then reheating to a temperature of 300 to 500 ° C.

When the hot rolling start temperature is 300 ° C. or lower, the deformation resistance becomes large and the rolling efficiency deteriorates, which is not preferable.
If the temperature exceeds 500 ° C, the crystal grains during rolling become coarse and the material tends to generate ridging marks.
It is necessary to regulate to ~ 500 ° C. Considering the deformation resistance and the uniformity of the worked structure, the rolling start temperature is preferably 380 to 450 ° C.

When the hot rolling end temperature exceeds 300 ° C., Mg-Si
Precipitation of the system compound is likely to occur, formability is likely to decrease, and recrystallized grains become coarse, which may cause ridging marks.Therefore, it is desirable that the end temperature of hot rolling be 300 ° C or less. 200 ° C considering the deformation resistance of the material during hot rolling and oil stain retention due to coolant
The above is preferable.

Solution heat treatment: Preferred solution heat treatment temperature is 45
It is 0 ° C or higher. If the temperature is lower than 450 ° C, the solid solution of Mg-Si-based precipitates becomes insufficient and sufficient strength and formability cannot be obtained, or a very long heat treatment is required to obtain the required strength and formability. Not industrially preferable. The solution heat treatment time is not particularly limited as long as it is performed within a range in which strength is obtained, but industrially it is generally maintained within 120 s.

Cooling rate during quenching: 12 from solution treatment temperature
It is necessary to cool down to 0 ° C or less at 5 ° C / s or more, and it is desirable to cool at a cooling rate of 10 ° C / s or more. If the quenching speed is too slow, precipitation of dissolved elements will occur and strength,
The BH property and moldability deteriorate, and the corrosion resistance also decreases.

Final heat treatment: 40-120 within 60 minutes after quenching
Heat treatment at ℃ for less than 50h. This treatment improves the BH conversion property. If the temperature is lower than 40 ° C, the BH property is not sufficiently improved, and if the temperature exceeds 120 ° C or the time exceeds 50 hours, the initial yield strength may be too high and the formability or the coating bake hardenability may be lowered.

In addition to the aluminum alloy having the above composition,
By applying the above manufacturing process, after the solution treatment and quenching, a texture with a high degree of integration of Cube orientation is returned,
The intensity ratio (random ratio) of the Cube orientation of the texture is 20
As described above, a plate material having excellent bending workability can be obtained. More preferably, the intensity ratio of the Cube orientation is set to 50 or more by adjusting the alloy components, particularly Si and Mg, and adjusting the manufacturing conditions. The aluminum alloy plate is used for, for example, an automobile hood, a trunk lid,
It is suitable for use as a lightweight automobile member with a complicated shape such as a door, and even when applied to fenders, roofs, etc. where hemming is not performed, it has excellent bending workability, making it a complex shape After press working, strict working with a small bending radius becomes possible, the range of application of aluminum materials to automobile materials is expanded, and it becomes possible to contribute to weight reduction of vehicle bodies.

[0037]

EXAMPLES Examples of the present invention will be described below in comparison with comparative examples. These examples show one embodiment of the present invention, and the present invention is not limited thereto.

Example 1 An aluminum alloy having the composition shown in Table 1 was cast by DC casting, and the obtained ingot was homogenized at 550 ° C. for 6 hours and then heated to 200 ° C. at 450 ° C./h. It cooled at the cooling rate.
Further, it was cooled to room temperature, reheated to a temperature of 420 ° C. to start hot rolling, and rolled to a thickness of 4.5 mm. The end temperature of hot rolling was 250 ° C.

Subsequently, cold rolling was performed to form a plate having a thickness of 1 mm, and further, solution treatment was performed at 540 ° C. for 20 s and 30 ° C.
Quenched to 120 ° C at a cooling rate of / s. 3 minutes after quenching
After that, heat treatment was performed at 100 ° C. for 3 hours.

Ten days after the final heat treatment, the aluminum alloy plate was subjected to a tensile test, and the paint bake hardenability (BH property), the Cube orientation strength ratio (random ratio) and the bending workability were evaluated by the following methods. The results are shown in Table 2.

Cube azimuth intensity ratio: An ODF analyzer is used to calculate the expansion order of even terms as 22nd and the expansion order of odd terms as 19th by the series expansion method proposed by Bunge.

Coating bake hardenability (BH property): After applying a tensile deformation of 2% and performing a heat treatment at 170 ° C. for 20 minutes, the yield strength is measured and the result is 200 MPa or more. Bending workability: After a pre-strain of 15%, a 180 ° bending test was conducted to investigate the limit bending radius, and an inner limit bending radius of 0.2 mm or less was passed.

[0043]

[Table 1] << Table Note >> B is ppm

[0044]

[Table 2]

As can be seen in Table 2, test material Nos. All of 1 to 7 are excellent in strength and BH property, and Cu
The strength ratio in the be direction exceeds 20, and it has excellent limit bending characteristics.

Comparative Example 1 An aluminum alloy having the composition shown in Table 3 was cast by DC casting, the obtained ingot was treated in the same process as in Example 1, and an aluminum alloy plate 10 days after the final heat treatment was performed. The tensile performance, the paint bake hardenability (BH property), the Cube orientation strength ratio, and the bending workability were evaluated in the same manner as in Example 1. The results are shown in Table 4.

[0047]

[Table 3] << Table Note >> B is ppm

[0048]

[Table 4]

As shown in Table 4, the test material No. 8 is Si
The amount is small and the test material Since No. 10 has a small amount of Mg, all of them have low strength and poor BH property. Test material No.
No. 9 has a large amount of Si, and the test material No. 11 has a large amount of Mg, and the value of 0.7 Si% + Mg% exceeds 2.2%.
All of them have high strength, low degree of integration in Cube orientation, and poor bending workability.

The test materials 12 to 16 are made of Cu and Mn, respectively.
Since the amount of Cr, the amount of Cr, the amount of V 2, and the amount of Zr are too large, the degree of integration in the Cube orientation becomes low and bending workability is poor.

Example 2, Comparative Example 2 Alloy B shown in Table 1 was DC cast, and the obtained ingot was cooled to 550
After homogenizing treatment for 5 h at ℃, 250 ℃ at the cooling rate shown in Table 5.
Then, it was heated to the temperature shown in Table 5 and hot-rolled to a thickness of 4.4 mm. The end temperature of hot rolling was 250 ° C. After cold rolling, thickness
The plate was 1 mm. Condition 26 only 400 ℃ -2h after hot rolling
Intermediate annealing was performed.

After that, a solution treatment for 5 s is performed at 550 ° C.,
Quenched to 120 ° C at a cooling rate of 30 ° C / s. After quenching 3
After min, heat treatment was performed at 100 ° C for 3 hours. With respect to the aluminum alloy plate manufactured by the above steps, the tensile performance, the BH property, the Cube orientation strength ratio, and the bending workability were evaluated by the same method as in Example 1.

Further, as an evaluation of the ridging mark, a tensile test piece was sampled in the rolling 90 ° direction and subjected to 10% tensile deformation to determine the presence or absence of the ridging mark after electrodeposition coating. The results are shown in Table 6.

[0054]

[Table 5]

[0055]

[Table 6] << Table Note >> Rising mark ○: Yes ×: No

As shown in Table 6, test material N according to the present invention
o. 17 to 21 are all excellent in strength and BH property, and Cu
The strength ratio in the be direction exceeds 20, and it has excellent limit bending characteristics.

On the other hand, the test material No. 22, 23
Caused a ridging mark because the hot rolling temperature was high. Test material No. In No. 24, since the cooling rate after the homogenization treatment is small, the degree of integration of Cube orientation is low and bending workability is poor. Test material No. In No. 25, the hot rolling temperature is high and the cooling rate after the homogenization treatment is low, so that ridging marks are generated, the degree of integration of Cube orientation is low, and bending workability is poor. Test material No. Since No. 26 was subjected to intermediate annealing,
The degree of integration of Cube orientation is low, and bending workability is poor.

[0058]

According to the present invention, there are provided an aluminum alloy sheet having excellent bending workability capable of flat hem processing, paint bake hardenability, and excellent corrosion resistance, and a method for producing the same. The aluminum alloy plate is suitably used as an automobile member having a complicated shape and a light weight, such as an automobile hood, a trunk lid, and a door, which are hem processed.

Front page continuation (51) Int.Cl. ⁷ Identification code FI theme code (reference) C22F 1/00 623 C22F 1/00 623 630 630K 682 682 683 683 685 685Z 686 686A 691 691B 692 692A 692B (72) Inventor Tadashi Minota 5-11-3 Shimbashi, Minato-ku, Tokyo Within Sumitomo Light Metal Industry Co., Ltd. (72) Inventor Mineo Asano 5-11-3, Shimbashi, Minato-ku, Tokyo Sumitomo Light Metal Industry Co., Ltd.

Claims (11)

[Claims] 1. A bending plate and a paint bake-hardening property, which are rolled sheets of an Al—Mg—Si-based aluminum alloy, wherein the formed texture has a Cube orientation strength ratio of 20 or more. Excellent aluminum alloy plate. 2. The Al-Mg-Si-based aluminum alloy comprises: Si: 0.5% to 2.0% (mass%, the same applies hereinafter), M
g: An aluminum alloy containing 0.2 to 1.5%, satisfying 0.7Si% + Mg% ≦ 2.2%, and an aluminum alloy consisting of the balance Al and impurities and having excellent bending workability and paint bake hardenability. Board. 3. The aluminum alloy plate further comprises Zn:
The aluminum alloy sheet excellent in bending workability and paint bake hardenability according to claim 1 or 2, which contains 0.5% or less (not including 0%, the same applies hereinafter). 4. The aluminum alloy plate further comprises Cu:
The aluminum alloy sheet having excellent bending workability and paint bake hardenability according to any one of claims 1 to 3, which contains 1.0% or less. 5. The aluminum alloy plate further comprises Mn:
1.0% or less, Cr: 0.3% or less, V: 0.2% or less, Z
r: 0.2% or less and one or more of them are contained, and the aluminum alloy plate excellent in bending workability and paint bake hardenability according to any one of claims 1 to 4. 6. The aluminum alloy plate further comprises Ti:
An aluminum alloy sheet having excellent bending workability and bake hardenability according to any one of claims 1 to 5, which contains at least one of 0.1% or less and B: 50 ppm or less. 7. A method for manufacturing an aluminum alloy plate according to claim 1, wherein the ingot of the aluminum alloy having the composition according to claim 1 is 45
After homogenizing at a temperature of 0 ° C or higher, it is cooled at a cooling rate of 100 ° C / h or higher to a predetermined temperature of lower than 350 ° C, hot-rolled at the predetermined temperature, and further cold-rolled, then 450 ° C or higher. A method for producing an aluminum alloy sheet having excellent bending workability and bake hardenability, which comprises performing solution treatment and quenching at the temperature of. 8. A method for producing an aluminum alloy plate according to claim 1, wherein the ingot of the aluminum alloy having the composition according to claim 1 is 45
After homogenizing at a temperature of 0 ° C or higher, cool it to a temperature of less than 350 ° C at a cooling rate of 100 ° C / h or more, then 300-500
Perform hot rolling to reheat to ℃ temperature and start rolling,
A method for producing an aluminum alloy sheet having excellent bending workability and bake hardenability, which is characterized by performing solution treatment and quenching at a temperature of 450 ° C. or higher after cold rolling. 9. A method for producing an aluminum alloy plate according to claim 1, wherein the ingot of the aluminum alloy having the composition according to any one of claims 1 to 6 is 45
After homogenizing at a temperature of 0 ℃ or more, cool to a temperature of less than 350 ℃ at a cooling rate of 100 ℃ / h or more, further cool to room temperature, then reheat to a temperature of 300 to 500 ℃ and start rolling. Hot rolling, then cold rolling, then 450 ℃
A method for producing an aluminum alloy sheet having excellent bending workability and bake hardenability, which comprises performing solution treatment and quenching at the above temperatures. 10. The method for producing an aluminum alloy sheet excellent in bending workability and bake hardenability according to claim 7, wherein the end temperature of the hot rolling is set to 300 ° C. or lower. . 11. Up to 120 ° C. is 5 ° C. after the solution heat treatment.
After quenching by cooling at a cooling rate of / s or more, after quenching
The method for producing an aluminum alloy sheet having excellent bending workability and bake hardenability according to any one of claims 7 to 10, wherein heat treatment is performed within 60 minutes at a temperature of 40 to 120 ° C for 50 hours or less.