JP2002146462A - Aluminum alloy sheet having excellent formability and its production method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a 6,000 series aluminum alloy sheet hard to be broken in pess forming, also generating little wrinkle, having a wide formabile range and suitable for an automobile body and to provide its production method. SOLUTION: This aluminum alloy sheet having excellent formability has a composition containing, by mass, 0.4 to 1.6% Si, 0.15 to 1% Mg, >=1% Mg+Si and 0.3 to 1.2% Cu, and the balance Al with inevitable impurities. Its 0.2% proof stress YS is <=150MPa, the difference with TS (TS-YS) is >=130MPa. Further, in Lankford values at 7.5% in each direction of 0 deg., 45 deg. and 90 deg. to the rolling direction, the minimum value rmin is >=0.6. Preferably, the tensile strength TS is >=220MPa, and, the average value rave of the Lankford values at 7.5% in each direction of 0 deg., 45 deg. and 90 deg. to the rolling direction is >=0.65. In its production method, process annealing is performed in the process of cold rolling. Further, after solution treatment, stabilization heat treatment at a low temperature about 100 deg.C or slow cooling from the same temperature is performed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a 6000 series aluminum alloy sheet which is hardly broken at the time of press forming, has less wrinkling, and has excellent formability, and a material for use in automobile body sheets and parts. It relates to a manufacturing method.

[0002]

2. Description of the Related Art In recent years, there has been an increasing demand for a reduction in the weight of a vehicle body for the purpose of improving fuel efficiency of an automobile. As one of means for reducing the weight, use of an aluminum alloy plate for an automobile body sheet or the like has been performed. Currently used car body seals
5000 aluminum alloy and 60
00 alloys. It is important that aluminum alloy sheets for automobiles have excellent press formability as workability. All aluminum alloy plates are more likely to break during press forming and to be more wrinkled than steel plates. Above all, 6000 series alloys are generally inferior in press formability to 5000 series alloys, are easily broken, and are apt to wrinkle.

[0003] The wrinkles occur on the flange portion and the body of the molded product, and not only deteriorate the appearance quality of the product, but also
The dimensional accuracy is also adversely affected. As a result, there are restrictions on the product shape and process design, and
There is a problem that the application of the 00 series alloy itself is hindered. That is, a 6000 series aluminum alloy that does not break in press forming and does not easily generate wrinkles is desired. There are various proposals regarding aluminum alloys having excellent press formability in that they are not easily broken, for example, Japanese Patent Application Laid-Open No. 10-102179 by the present inventors. However, with regard to the reduction of wrinkles during press molding, for example, JP-A-2-37922 and JP-A-9-6632
As disclosed in Japanese Patent Publication No. 0, there is proposed a method of avoiding wrinkles by a press molding method. However, at present, it cannot be said that the proposal as a material that suppresses the generation of wrinkles and has excellent fracture resistance is sufficient.

[0004]

SUMMARY OF THE INVENTION In view of such circumstances, the present invention provides a 6000 series aluminum alloy sheet which is less likely to break during press forming and has less wrinkles and excellent formability, and a method for producing the same. It is intended for that purpose.

[0005]

Means for Solving the Problems In order to achieve the above object, the present inventors have eagerly studied the effects of the forming style and various material factors on the breakage during press forming and the occurrence of wrinkles in the flange and the body. Study was carried out. As a result of various studies, the upper limit value of YS was 150 MPa or less, (T
(S-YS) value of 130 MPa or more, r _min of 0.6 or more, and TS of 220 MPa or more and r _ave of 0.65 or more, are less likely to break during press forming and have wrinkles. It has been found that the occurrence is reduced.

Here, YS is 0.2% proof stress, TS is tensile strength, r _min and r _ave are 0 °, 45 ° with respect to the rolling direction,
Of the Rankford values at 7.5% in each direction at 90 °,
These are the minimum and average values, respectively. In particular, the average value r _ave is obtained by r _ave = (r0 ° + r90 ° + 2 × r45 °) / 4, where r0 °, r90 °, and r45 ° are 0 °, 90 °, and 45 °, respectively. This is the Rankford value when the directional distortion is 7.5%.

The generation of wrinkles is a phenomenon in which the material shrinks in width due to the inflow of a material in deep drawing and the sheet thickness increases to cause buckling. By defining the upper limit value of YS, it becomes difficult to reach the buckling limit in the width shrinkage deformation during deep drawing, and the occurrence of wrinkles is suppressed. In addition, even if the wrinkle pressing force is increased to remove wrinkles, the material does not break if it has a predetermined (TS-YS) value and r _min value, and has sufficient deep drawability and stretch formability. .
That is, it can be seen that if the YS, (TS-YS) value, and r _min are specified to appropriate values, a 6000 series aluminum alloy having excellent writability and less breakage during press forming and excellent in formability can be obtained. Was.

[0008] In wrinkling, in addition to the YS, preferably defines the lower limit of r _{av e} Another factor. Thereby, the width shrinkage deformation is facilitated, and wrinkles are less likely to occur. In the case of breaking, TS-YS
In addition to and r _min , preferably, another factor defines the lower limit of TS. Since the fracture occurs when the strength of a certain portion exceeds the TS, defining the lower limit of the TS is equivalent to increasing the molding amount up to the fracture, and as a result, it is difficult to fracture.

An alloy for obtaining such characteristic values
Intensive studies were also made on components and production methods. Sand
That is, the amount of Mg, Si, and Cu is defined, and the texture is controlled.
Hope r _minHeat treatment during cold rolling to obtain
The desired YS value even if left at room temperature for a long time.
In order to secure, at low temperature around 100 ° C after solution treatment
Stabilizing heat treatment or slowly cooling from that temperature
I found something good.

The present invention has been obtained based on the above findings, and the gist thereof is as follows. (1) In mass%, Si: 0.4 to 1.6%, Mg:
0.15% to 1%, Mg + Si: 1% or more, the balance being Al and unavoidable impurities, 0.2% proof stress YS
Is 150 MPa or less, the difference from the tensile strength TS (TS-Y
S) is 130 MPa or more, and the minimum value r _{min of the} Rankford value at 7.5% in each of 0 °, 45 °, and 90 ° with respect to the rolling direction is 0.6 or more. Aluminum alloy plate with excellent formability characterized by the following.

(2) Further, the tensile strength TS is 220MP.
The average value r _{ave of the} Rankford value at 7.5% in each of 0 °, 45 °, and 90 ° with respect to the rolling direction is 0.
The aluminum alloy sheet having excellent formability according to the above (1), wherein the aluminum alloy sheet has a diameter of 65 or more. (3) The aluminum alloy sheet having excellent formability according to the above (1) or (2), further comprising 0.3 to 1.2% of Cu by mass%.

(4) In mass%, Ti: 0.005 to
0.15%, B: 0.0001-0.05%, Mn:
0.03-0.4%, Cr: 0.02-0.15%, F
e: 0.05 to 0.4%, Zn: 0.03 to 1.5%, one or more of which are further contained, any one of the above (1) to (3) 2. An aluminum alloy excellent in formability according to item 1.

(5) Any one of the above (1) to (4)
In the production of the aluminum alloy sheet described in the paragraph, in the course of cold rolling, 0.5 to 2 at a temperature range of 250 to 400 ° C.
Intermediate annealing is performed for 4 hours or within a range of 450 to 580 ° C for 5 minutes or less, and after the intermediate annealing, cold rolling of 15 to 70% is performed.
An aluminum alloy plate excellent in formability, characterized by performing a heat treatment in a temperature range of 0 ° C., cooling at a cooling rate of 10 ° C./s or more, and then performing a stabilizing heat treatment in a range of 70 to 150 ° C. for 1 to 50 hours. Manufacturing method.

(6) Any one of the above (1) to (4)
In the production of the aluminum alloy sheet described in the paragraph, in the course of cold rolling, 0.5 to 2 at a temperature range of 250 to 400 ° C.
Intermediate annealing is performed for 4 hours or within a range of 450 to 580 ° C for 5 minutes or less, and after the intermediate annealing, cold rolling of 15 to 70% is performed.
Perform at a temperature range of 0 ° C. and at a cooling rate of 10 ° C./s or more.
The plate is cooled to a temperature in the range of ~ 150 ° C, followed by a cooling rate of 0.1 ° C.
This is a method for producing an aluminum alloy sheet excellent in formability, characterized by gradually cooling to 40 ° C. at 5 to 5 ° C./h.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail. First, the reason for limiting the suitable range of the mechanical characteristic value in the present invention will be described. By defining the upper limit value of YS, it is difficult to reach the limit stress that causes buckling in width shrinkage deformation during deep drawing and has an effect of suppressing wrinkles. If YS exceeds 150, the effect of suppressing wrinkles will be insufficient. YS is preferably 140 or less in order to obtain a higher wrinkle suppressing effect. YS
The lower the is, the higher the effect of suppressing the generation of wrinkles, but it is necessary to secure a YS value for obtaining a predetermined strength after molding as an automobile part.

Further, even if the wrinkle holding force is increased to remove wrinkles, the material does not break if the predetermined (TS-YS) value and r _min value are provided, and sufficient deep drawing formability and overhanging property can be obtained. Having. When the (TS-YS) value is less than 130 and the _rmin value is less than 0.6, the effect becomes insufficient. Therefore, the (TS-YS) value is specified to be 130 or more and the _rmin value is specified to be 0.6 or more. In order to obtain a higher effect as described above, the (TS-YS) value is preferably 135 or more, and the _rmin value is preferably 0.65 or more.

[0017] In order to further suppress wrinkling, it is effective provision of the lower limit of r _{av e} in addition to the provisions of the lower limit of the above YS. By defining the lower limit value of r _ave, the shrinkage and deformation of the width becomes easy and the buckling becomes difficult, so that the wrinkle hardly occurs. In order to make it more difficult to break,
It is effective to specify the lower limit value of. The lower limit value of the TS is to increase the strength of the fracture site, whereby the fracture hardly occurs in deep drawing. In order to obtain such an effect as much as possible, r _ave is desirably 0.72 or more and TS is desirably 260 MPa or more.

Next, the reason for limiting the preferable component range for obtaining the mechanical characteristic value in the present invention will be described. Mg, Si: Mg and Si are indispensable basic components of the present invention, and are contained in order to form a fine precipitated phase and obtain moldability and strength. As a component range, Mg: 0.15
1 mass%, Si: 0.4 to 1.6 mass%, and a range satisfying the relational expression of Mg + Si ≧ 1 mass%. Mg is less than 0.15% by mass, and Si is 0.1% by mass.
Less than 4 mass% or 0.15 mass% of Mg
% +, Even if Si is 0.4 mass% or more, Mg + Si
If it is less than 1.0, sufficient characteristics cannot be obtained.

Mg is more than 1 mass%, Si is 1.6 ma
If it exceeds ss%, when solution is treated by containing Cu, M
g ₂ Si, Si, second phase such as Al-Cu-Mg-Si based compound will be precipitated on the grain boundaries, the moldability is lowered significantly. Cu: Cu is also a basic component of the present invention, and is contained mainly to raise TS by solid solution strengthening to improve the (TS-YS) value. The component range is 0.4 to 1.2
mass%. If Cu is less than 0.4 mass%, the effect of improving the (TS-YS) value is insufficient. If Cu is more than 1.2 mass%, bending workability and corrosion resistance are significantly reduced. Further, in view of the above-mentioned characteristic improvement, 0.1.
It is preferable to contain 6 mass% or more of Cu.

In the present invention, if necessary,
One or more of Ti, B, Mn, Fe, and Zn may be contained. Ti, B: Ti and B have the effect of refining the crystal grains of the ingot by adding a small amount to improve the press formability and the like.
Ti: 0.005% or more and B: 0.
Add 0001% or more. On the other hand, the content of Ti is 0.1.
15 mass% or less, B content is 0.05 mass%
It is preferable to define it in the following range. Each content is Ti 0.15 mass%, B 0.05 mass%
If more than 0.1%, coarse crystallized substances are formed and the moldability deteriorates. Therefore, 0.15% by mass and 0.05% by mass respectively.
Is preferably the upper limit.

Mn: Mn improves the strength by adding 0.03% or more. On the other hand, if the content exceeds 0.4 mass%, coarse crystals are formed, and the moldability is reduced. Fe: If Fe is less than 0.05%, the effect of improving the strength is small, and if its content exceeds 0.4 mass%, coarse crystals are formed, and the formability is reduced. Zn: Zn improves the strength by adding 0.03% or more. On the other hand, if the content exceeds 1.5 mass%,
In the alloy of the present invention, the formability is reduced. In addition to the above-mentioned elements, unavoidable impurities are contained as in the case of ordinary aluminum alloys, but the amount thereof is acceptable as long as the effects of the present invention are not impaired.

Next, a preferred method for producing the 6000 series alloy of the present invention will be described in detail. The aluminum alloy having the alloy component of the present invention may be cast and hot-rolled according to a conventional method. Subsequently, cold rolling is performed to obtain a desired sheet thickness. In this cold rolling step, primary cold rolling is performed, and after performing intermediate annealing for recrystallizing the sheet, secondary cold rolling is performed. Thus, the amount of strain introduced during the secondary cold rolling is reduced during recrystallization during cold rolling, during the solution treatment defined below, a suitable recrystallization texture is formed Thus, an r _min value of 0.6 or more and a r _ave value of 0.65 or more specified in the present invention can be obtained.

If intermediate annealing is not performed during cold rolling, the amount of strain accumulation due to cold rolling increases, and a texture with a large accumulation of cubic orientations is formed at the time of performing the solution treatment. The above r _min value and r _ave value of 0.65 or more cannot be obtained. When the intermediate annealing is performed using a batch furnace, it is appropriate to set the temperature in a temperature range of 250 to 400 ° C. to 0.5 to 24 hours. If the intermediate annealing temperature in the batch furnace is lower than 250 ° C., the intermediate annealing effect cannot be sufficiently obtained, and if it exceeds 400 ° C., the recrystallized grains may become coarse and the formability may be reduced. If the intermediate annealing time in the batch furnace is less than 0.5 hours, the intermediate annealing effect cannot be sufficiently obtained, and if it exceeds 24 hours, the formability may be reduced.

When the intermediate annealing is performed by using a continuous annealing furnace, the temperature is in the range of 450 to 580 ° C. for 5 minutes.
The following holds are appropriate. In this case, if the annealing temperature is lower than 450 ° C., a sufficient annealing effect cannot be obtained, and if it exceeds 580 ° C., recrystallized grains may become coarse and formability may be reduced. Further, even if the temperature is maintained for more than 5 minutes, the recrystallized grains may be coarsened and the formability may be reduced.

Further, since the cold rolling reduction after the intermediate annealing until the final annealing affects the recrystallization texture formation behavior at the time of the final annealing, the range of the cold rolling reduction after the intermediate annealing is 15 to 15. 70%. Cold rolling reduction after intermediate annealing is 15
If it is less than%, sufficient recrystallization does not occur at the time of final annealing, or even if recrystallization occurs, recrystallized grains become coarse and the formability decreases. If it is 70% or more, a cubic texture is likely to be formed at the time of final annealing, and the r _min value and the r _ave value will be small.

In order to obtain the formability of the present invention, after cold rolling, 450-580 using a continuous annealing furnace as final annealing.
It is preferable to perform a solution treatment at a temperature in the range of ° C. and to cool at a cooling rate of 10 ° C./s or more. As a solution treatment condition in the above step, at a temperature of 450 ° C. or less, solute atoms contributing to moldability and paint bake hardenability do not sufficiently form a solid solution in the Al matrix, but precipitate as a second phase. Therefore, sufficient formability cannot be obtained, and the hem bending property decreases. On the other hand, if the solution temperature exceeds 580 ° C,
The recrystallized grains may be coarsened, causing not only rough skin but also partial melting. Therefore, the solution treatment temperature was set in the range of 450 to 580 ° C. Regarding the holding at the solution temperature, if the solid solution of the solute atoms is sufficiently performed, a certain holding time may be taken without holding (cooling immediately after reaching the solution treatment temperature). .

If the cooling rate after the solution treatment is set to less than 10 ° C./s, the second phase precipitates during cooling, the hem bending property decreases, and the supersaturated solid solution amount of solute atoms decreases. Predetermined formability cannot be obtained. Therefore, the cooling rate after the solution treatment temperature was set to 10 ° C./s or more. After solution treatment, aging is suppressed during storage at room temperature after production, and YS is 150
In order not to exceed Pa, a stabilizing heat treatment is performed at 70 to 150 ° C. for 1 to 50 hours. By performing this stabilization treatment immediately after the solution treatment, good paint baking curability can be obtained.

The reason for defining the heat treatment range is that the temperature is 70 ° C.
If the treatment is carried out for less than 1 hour, a sufficient effect of suppressing the change with time cannot be obtained, and if it exceeds 150 ° C. and exceeds 50 hours, on the contrary, the strength rise becomes too large, and YS exceeds 150 MPa. The effect almost equivalent to this stabilizing heat treatment is that after cooling the plate at a rate of 10 ° C./s to a range of 70 to 150 ° C. after the solution treatment, the temperature is reduced by 0.5%.
It can also be obtained by slowly cooling down to 40 ° C. at ５5 ° C./h.

The reason for defining the range of the heat treatment is as follows.
If the temperature is less than 5 ° C./h, a sufficient effect of suppressing a change with time cannot be obtained. If the temperature exceeds 150 ° C., and if the temperature is less than 0.5 ° C./h, the strength increase becomes too large, and YS exceeds 150 MPa. This is because The 60 thus obtained
The 00-based aluminum alloy sheet has characteristics that it is hardly broken during press forming and hardly generates wrinkles, and is suitable as a material for automobile bodies and the like.

[0030]

The present invention will be described below with reference to examples. (Example 1) An alloy having a composition as shown in Table 1 was melted and cast by a usual method, and hot-rolled to obtain a plate having a thickness of 5 mm.
Of the board. Then, the hot-rolled sheet was cold-rolled to 2.5 mm, then subjected to intermediate annealing at 520 ° C. for 30 seconds, and further subjected to secondary cold rolling to a sheet thickness of 1 mm (corresponding to 60%). . Then, a solution treatment was carried out at 520 ° C. for 30 seconds, followed by air cooling at an average cooling rate of 20 ° C./s, followed by a stabilizing heat treatment at 90 ° C. for 5 hours to produce an aluminum alloy sheet. After being left at room temperature for three months after the production, tensile properties, deep drawability, and overhang properties were evaluated.

[0031]

[Table 1]

The tensile properties were evaluated by examining 0.2% proof stress, tensile strength and elongation in a direction perpendicular to the rolling direction. The r _min and r _ave values are 0 °, 45 °,
It was determined by examining the Rankford value at 7.5% elongation in each direction at 90 °. The deep drawability is evaluated by changing the wrinkle holding force by the cylindrical deep drawing test and forming it within the range that can be formed (the amount of wrinkle holding force that does not generate wrinkles and does not break: ton).
Was evaluated. The test conditions were: punch diameter 100 mm
φ, punch shoulder R10 mm, die shoulder R10 mm, blank size 190 mm, lubricating oil was used as rust preventive oil, molded up to 40 mm, observed wrinkle generation at the flange part, and fractured, and evaluated the moldable range described above. . Here, wrinkles are undulations having a height of 0.2 mm or more. In this evaluation method, if the moldable range is 3 tons or more, 500
Good deep drawability equal to or higher than that of the 0-base alloy was indicated.

The overhanging property was evaluated by sticking vinyl chloride to a plate and performing lubrication under a good condition with a 100φ ball head. 5000 mm if 36 mm or more in this test result
It had good stretch formability equal to or higher than the system. Further, in order to evaluate the paint bake hardenability, a heat treatment was performed at 170 ° C. for 20 minutes corresponding to the paint bake treatment after giving a prestrain of 2% corresponding to the processing received by the press, and the proof stress was examined. Table 2 shows the results of these investigations.

From Table 2, it can be seen that the aluminum alloy sheet N of the present invention
o. It can be seen that Nos. 1 to 15 have a wide moldable range of 3 tons or more. In addition, the ball head overhang height is 36 mm or more, and the overhang formability is also combined. Furthermore, it has good paint bake hardenability. On the other hand, the alloy No. of the comparative example having components other than the present invention. In the case of 16 to 21, the moldable range is narrowed, and the overhang formability is not necessarily good. The same applies to paint bake curability. That is, according to the present invention, it is possible to manufacture an aluminum alloy plate having good formability.

[0035]

[Table 2]

Example 2 Inventive alloy 13 shown in Table 1 was melted, cast and hot-rolled by a conventional method to obtain a plate having a thickness of 5 mm. The hot-rolled sheet was subjected to primary cold rolling under the conditions shown in Table 3, and then subjected to intermediate annealing, and further to a sheet thickness of 1 m.
m was subjected to secondary cold rolling. Further, an aluminum alloy plate was manufactured by performing a solution heat treatment / air cooling followed by stabilizing heat treatment or slow cooling treatment. Table 3 shows the conditions of the intermediate annealing, the cold rolling ratio after the intermediate annealing, the solution treatment conditions, the cooling rate after the solution treatment, the stabilized heat treatment conditions, and the slow cooling conditions.

[0037]

[Table 3]

The same investigation as in Example 1 was carried out on the aluminum alloy plate thus produced. Table 4 shows the results of the investigation. From Table 4, it can be seen that the production method of the aluminum alloy sheet of the present invention is No. 1 to 12 show that the moldable range is as wide as 3 tons or more. In addition, the ball head overhang height is 36 mm or more, and the overhang formability is also combined. Furthermore, it has good paint bake hardenability.
On the other hand, the alloy No. of the comparative example manufactured by a manufacturing method other than the present invention. In the case of 13 to 24, the moldable range is narrowed, and the stretch formability is not necessarily good. The same applies to paint bake curability. Thus, it can be seen that those processed under the manufacturing conditions in the present invention have excellent moldability with respect to the manufacturing conditions of the above-described comparative example.

[0039]

[Table 4]

[0040]

According to the present invention, there is provided a 6000 series aluminum alloy sheet suitable for use in an automobile body which requires a wide range of press formability, press formability, appearance quality and dimensional accuracy, and a method for producing the same. It can greatly contribute to reducing the weight of automobiles. Therefore, it can be said that the industrial value of the present invention is extremely high.

──────────────────────────────────────────────────続 き Continuation of the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C22F 1/00 630 C22F 1/00 630K 685 685Z 686 686B 691 691B 691C 692 692A 692B 694 694A (72) Inventor Makoto Saga 20-1 Shintomi, Futtsu-shi, Chiba Nippon Steel Corporation Technology Development Division (72) Inventor Toshiki Matsumura 1-2-1 Kinshi, Sumida-ku, Tokyo Sky Aluminum Co., Ltd. (72) Inventor Osamu Noguchi Sky Aluminum Co., Ltd. 1-2-1, Kinshi, Sumida-ku, Tokyo

Claims (6)

[Claims] 1. The composition contains, as mass%, Si: 0.4 to 1.6%, Mg: 0.15 to 1%, and Mg + Si: 1% or more, with the balance being Al and unavoidable impurities,
The 0.2% proof stress YS is 150 MPa or less, the difference (TS-YS) from the tensile strength TS is 130 MPa or more, and 7.5% in each of 0 °, 45 °, and 90 ° with respect to the rolling direction.
The minimum value r _{min of the} Rankford values at is 0.6
An aluminum alloy plate excellent in formability, characterized in that: Further, the average value r _{ave of the} Rankford value at 7.5% in each of 0 °, 45 ° and 90 ° with respect to the rolling direction has a tensile strength TS of 220 MPa or more, and the average value r _ave is 0.6.
The aluminum alloy plate excellent in formability according to claim 1, wherein the number is 5 or more. 3. The aluminum alloy sheet excellent in formability according to claim 1, further comprising 0.3 to 1.2% by mass of Cu. 4. Mass%, Ti: 0.005 to 0.15%, B: 0.0001 to 0.05%, Mn: 0.03 to 0.4%, Cr: 0.02 to 0. 4. The method according to claim 1, further comprising one or more of 15%, Fe: 0.05 to 0.4%, and Zn: 0.03 to 1.5%. 2. An aluminum alloy excellent in formability according to item 1. 5. The method of manufacturing an aluminum alloy sheet according to claim 1, wherein the cold rolling is performed in the temperature range of 250 to 400 ° C. for 0.5 to 24 hours, or 450 to 400 hours. Intermediate annealing for 5 min or less is performed in the range of 580 ° C, cold rolling of 15 to 70% is performed after the intermediate annealing, and then final solution treatment is performed in a temperature range of 450 to 580 ° C and 10 ° C / s or more. A method for producing an aluminum alloy sheet excellent in formability, comprising performing a stabilizing heat treatment at 70 to 150 ° C. for 1 to 50 hours after cooling at a cooling rate. 6. The method for producing an aluminum alloy sheet according to claim 1, wherein the cold rolling is performed at a temperature in the range of 250 to 400 ° C. for 0.5 to 24 hours or 450 to 400 hours. Intermediate annealing for 5 min or less is performed in the range of 580 ° C, cold rolling of 15 to 70% is performed after the intermediate annealing, and then final solution treatment is performed in a temperature range of 450 to 580 ° C and 10 ° C / s or more. 70-150 at cooling rate
The plate is cooled to a temperature in the range of 0.5 ° C.
A method for producing an aluminum alloy sheet excellent in formability, characterized by gradually cooling to 40 ° C./h.