JP2019026876A - Aluminum alloy sheet and method for producing the same - Google Patents

Abstract

To provide an aluminum alloy sheet that has high tensile strength and also has excellent press molding ability and stress corrosion crack resistance, particularly an Al-Mg aluminum alloy sheet, and a method of producing the same.SOLUTION: An aluminum alloy sheet contains, in mass%, Si: 0.03-0.35%, Fe: 0.03-0.35%, Mg: 3.0-5.0%, Cu: more than 0.09% and less than 0.50%, and Mn: more than 0.05% and 0.35% or less, with the balance being Al and inevitable impurities.SELECTED DRAWING: None

Description

  The present invention includes, for example, automobile body seats, members and parts used in various automobiles represented by body panels, members and parts used in ships, aircrafts, etc., building materials, structural materials, and other various machine tools, Aluminum alloy plates used as materials for home appliances and their parts, such as molding and paint baking, especially Al- having excellent tensile strength and stress corrosion cracking resistance while having high tensile strength The present invention relates to an Mg-based aluminum alloy plate and a manufacturing method thereof.

  Conventionally, cold-rolled steel sheets were often used for body seats used in automobiles, but recently, from the perspective of reducing global warming and reducing energy costs, the weight of automobiles has been reduced to improve fuel efficiency. Therefore, instead of the conventional cold-rolled steel sheet, there is an increasing tendency to use an aluminum alloy sheet having approximately the same strength as the cold-rolled steel sheet and a specific gravity of about 1/3 for the body sheet of an automobile. .

  By the way, as an aluminum alloy for automobile body sheets, an Al—Mg alloy, for example, a 5000 series Al alloy containing 3.5% by mass or more of Mg such as 5056, 5082, 5182, 5083, and 5086 is used. These Al—Mg alloys are used as welded structural members because of their high strength, good formability, and excellent weldability.

  However, when the above Al—Mg-based alloy is used as a structural material in a state where stress is applied for a long time, there is a problem that stress corrosion cracking is likely to occur because the Mg content is large. In order to prevent this stress corrosion cracking, it is effective to apply a surface treatment such as coating on a base material made of an Al-Mg alloy, but this base material must be used without coating as a structural material. In some cases, the base material itself made of an Al—Mg alloy is required to have excellent stress corrosion cracking resistance.

It is known that stress corrosion cracking in an Al-Mg based alloy is promoted by the β phase (Al ₃ Mg ₂ ) that preferentially and continuously precipitates at the grain boundary with the passage of time. ing. For this reason, conventionally, in order to prevent stress corrosion cracking of an Al—Mg alloy having a high Mg content, various proposals have been made to suppress continuous precipitation on the grain boundaries of the β phase.

  For example, Patent Document 1 discloses that cooling after performing a solution treatment subsequent to hot rolling and cold rolling is performed in two stages under conditions of different cooling rates in a high temperature region and a low temperature region, The manufacturing method of the Al-Mg-Cu-type aluminum alloy plate for shaping | molding which can prevent the continuous precipitation of (beta) phase to the grain boundary under cooling by making the cooling rate in (3) faster is described.

Patent Document 2 includes Mg: 3.5 to 5.5%, the strength after the final annealing treatment is 250 N / mm ² or more, and the electrical conductivity after the annealing treatment is 26.5 to 29. A structural aluminum alloy plate having 6 IACS% is described. According to such description, the electrical conductivity is 29.6 IACS% or less, and the total precipitate including the β phase is in a precipitated and solid solution state. The stress corrosion cracking resistance can be improved without degrading the characteristics.

JP 2003-231956 A JP 2001-32031 A

  However, since the aluminum alloy plate described in Patent Document 1 has a high Cu content of 0.5 to 1.8 mass%, hot workability is reduced and a coarse compound is formed, resulting in poor formability. In addition, in order to manufacture such an aluminum alloy plate, it is necessary to perform cooling after the solution treatment in two stages and to increase the cooling rate in the low temperature range. If the speed is increased, there is a problem that the shape accuracy such as flatness after processing is deteriorated.

  In addition, the structural aluminum alloy plate described in Patent Document 2 has only Mg as an essential component, and is limited in strength and conductivity after the final annealing treatment, but contains a specific component other than Mg. However, there is no disclosure or suggestion on the influence of tensile strength, press formability and stress corrosion cracking resistance, and in order to manufacture such an aluminum alloy sheet, the cooling rate during casting As well as an increase in the number of manufacturing steps and manufacturing conditions, in the intermediate annealing during cold rolling and the cooling after heating in the final annealing after cold rolling. There is a problem in that productivity is reduced by strict control.

  The present invention has been made paying attention to such circumstances, and its purpose is to provide an aluminum alloy plate having a high tensile strength and excellent in press formability and stress corrosion cracking resistance. An Al—Mg-based aluminum alloy plate and a method for producing the same are provided.

  In order to solve the above problems, the present inventors conducted various experiments and studies on the composition components and manufacturing processes of Al-Mg alloys, and limited the composition components and manufacturing processes to appropriate conditions. Has found that it is possible to control the size and number density of the intermetallic compounds present in the aluminum alloy sheet, thereby maintaining excellent press formability and stress corrosion cracking resistance while maintaining high tensile strength. As a result, the present invention has been completed.

That is, the gist configuration of the present invention is as follows.
(1) By mass%, Si: 0.03-0.35%, Fe: 0.03-0.35%, Mg: 3.0-5.0%, Cu: 0.09% over 0.50 % And Mn: more than 0.05% and not more than 0.35%, and the balance has a composition consisting of Al and inevitable impurities.
(2) In the above (1), the equivalent circle diameter is 0.1 to 0.5 μm, and the number density of the intermetallic compound not containing Cu is 1 × 10 ⁶ pieces / mm ² or less. The aluminum alloy plate as described.
(3) The circle equivalent diameter is 0.3 to 4 μm, and the number density of the intermetallic compound containing Cu is 1 × 10 ⁴ pieces / mm ² or more. The aluminum alloy plate described in).
(4) The aluminum alloy plate according to any one of (1) to (3) above, wherein Cu: 0.13 to 0.35 mass%.
(5) The above composition (1) to (4), wherein the composition further contains one or two of Ti: 0.05% by mass or less and B: 0.05% by mass or less. The aluminum alloy plate according to any one of the above.
(6) A method for producing the aluminum alloy plate according to any one of (1) to (5) above, wherein an ingot obtained by casting an aluminum alloy material having the above composition is 490 to 580. A homogenization treatment is performed at a first temperature within a range of ℃, and then an average cooling rate is within a range of 500 to 3000 ℃ / h within a range of 430 to 500 ℃ and lower than the first temperature. After cooling to be inside, hot rolling is started at the second temperature, and then winding is performed at a third temperature within a range of 320 to 380 ° C., and then cold rolling and final annealing treatment are performed. A method for producing an aluminum alloy plate characterized by sequentially performing the steps.
(7) The first temperature is in a range of 500 to 570 ° C, the second temperature is in a range of 440 to 490 ° C, and the third temperature is in a range of 340 to 360 ° C. The method for producing an aluminum alloy plate according to (6) above.

  According to the present invention, by mass%, Si: 0.03-0.35%, Fe: 0.03-0.35%, Mg: 3.0-5.0%, Cu: more than 0.09% By containing less than 0.50% and Mn: more than 0.05% and not more than 0.35% and the balance being composed of Al and unavoidable impurities, the press formability and It has become possible to provide an aluminum alloy plate excellent in stress corrosion cracking resistance, particularly an Al-Mg based aluminum alloy plate and a method for producing the same.

Next, a preferred embodiment of the present invention will be described.
The aluminum alloy plate according to the present invention is mass%, Si: 0.03-0.35%, Fe: 0.03-0.35%, Mg: 3.0-5.0%, Cu: 0.09% It contains more than 0.50% and Mn: more than 0.05% and less than 0.35%, with the balance being composed of Al and inevitable impurities.

  Hereinafter, the reasons for limiting the chemical composition of the aluminum alloy sheet according to the present invention will be shown. The unit of element content in the chemical composition is “% by mass”, but hereinafter, it is simply indicated by “%” unless otherwise specified.

(I) Chemical composition <Si: 0.03-0.35%>
Si (silicon) has an effect of improving stress corrosion cracking resistance and is one of the important components in the present invention. If the Si content is less than 0.03%, preferential precipitation at the grain boundary of β phase (Al ₃ Mg ₂ ) cannot be prevented, stress corrosion cracking resistance is deteriorated, and the crystal grains after the final annealing are deteriorated. It is because it becomes coarse and it becomes easy to generate rough skin. On the other hand, if the Si content exceeds 0.35%, an intermetallic compound is formed, and the press formability, particularly the stretchability and deep drawability deteriorate. For this reason, Si content is taken as 0.03 to 0.35% of range, preferably 0.09 to 0.25%.

<Fe: 0.03 to 0.35%>
Fe (iron) also has the effect of improving the stress corrosion cracking resistance like Si, and is one of the important components in the present invention. If the Fe content is less than 0.03%, preferential precipitation at the grain boundary of β phase (Al ₃ Mg ₂ ) cannot be prevented, stress corrosion cracking resistance is deteriorated, and the crystal grains after the final annealing are deteriorated. It becomes coarse and rough skin is likely to occur. On the other hand, if the Fe content exceeds 0.35%, an intermetallic compound is formed, and the press formability, particularly the stretchability and deep drawability deteriorate. For this reason, the Fe content is in the range of 0.03 to 0.35%, preferably in the range of 0.09 to 0.25%.

<Mg: 3.0-5.0%>
Mg (magnesium) is a component having an action of increasing work hardenability and improving stretchability and deep drawability. In order to exhibit this effect, it is necessary to contain Mg content of 3.0% or more. Further, even if the Mg content exceeds 5.0%, not only a further improvement effect of the above characteristics can be expected, but also the stress corrosion cracking resistance and the hot rolling property are remarkably lowered. Therefore, the Mg content is in the range of 3.0 to 5.0%, preferably in the range of 3.2 to 4.7%.

<Cu: more than 0.09% and less than 0.50%>
Cu (copper), like Mg, is a component that has the effect of increasing work hardening and improving the stretchability and deep drawability. Moreover, Cu also has the effect | action which suppresses the grain boundary precipitation of (beta) phase and improves stress corrosion cracking resistance by forming the Al-Mg-Cu type compound. In order to exhibit such an effect, it is necessary to make the Cu content exceed 0.09%. On the other hand, when the Cu content is 0.50% or more, the hot workability is lowered and a coarse compound is formed, and the press formability is lowered. For this reason, the Cu content is in the range of more than 0.09% and less than 0.50%, preferably in the range of 0.09 to 0.35%.

<Mn: 0.05% to 0.35% or less>
Mn (manganese) is a component having a function of refining recrystallized grains after the final heat treatment and improving strength. In order to exert the above action, the Mn content needs to exceed 0.05%. On the other hand, if the Mn content exceeds 0.35%, the size of the recrystallized grains becomes too small, and the stretcher strain mark (distortion pattern (wrinkle appearing on the surface of the alloy plate) appears on the surface of the pressed alloy plate. )) Is more likely to occur, and the moldability also decreases.

  As described above, the aluminum alloy plate of the present invention contains Si, Fe, Mg, Cu, and Mn as essential components, but if necessary, Ti: 0.05% or less and B: 0.05% or less One or two of them can be further contained.

<One or two of Ti: 0.05% or less and B: 0.05% or less>
Ti and B are components having an action of refining crystal grains of the ingot. If both the contents of Ti and B are not more than 0.05%, the press formability and stress corrosion cracking resistance are not adversely affected.

<Balance: Al and inevitable impurities>
In addition to the above elements, there are Al (aluminum) and inevitable impurities.

  Even if V, Sc, Na, Be, Bi is contained in the range of 0.1% or less, there is no influence on the implementation of the present invention.

(II) Number density of intermetallic compounds (i) The equivalent circle diameter is 0.1 to 0.5 μm, and the number density of intermetallic compounds not containing Cu is 1 × 10 ⁶ pieces / mm ² or less. The aluminum alloy plate of the present invention has an equivalent circle diameter of 0.1 to 0.5 μm, and the number density of intermetallic compounds not containing Cu is preferably 1 × 10 ⁶ pieces / mm ² or less. Intermetallic compounds that do not contain Cu have an equivalent circle diameter of more than 0.5 μm or a number density of more than 1 × 10 ⁶ pieces / mm ² , resulting in reduced press formability and stress corrosion cracking resistance. Because there is a tendency to. Further, if the equivalent circle diameter of the intermetallic compound not containing Cu is less than 0.1 μm, although the moldability is good, the stress corrosion cracking resistance tends to decrease. For this reason, the circle equivalent diameter is 0.1 to 0.5 μm, and the number density of the intermetallic compound not containing Cu is preferably 1 × 10 ⁶ pieces / mm ² or less. The lower limit of the number density of intermetallic compounds not containing Cu is not particularly limited, but is preferably 0.5 × 10 ⁴ pieces / mm ² from the viewpoint of press formability. Here, the “equivalent circle diameter” means a diameter (equivalent circle diameter) when the area of the observed particles is converted into a circle equivalent.

(Ii) The circle equivalent diameter is 0.3 to 4 μm, and the number density of the intermetallic compound containing Cu is 1 × 10 ⁴ pieces / mm ² or more. The aluminum alloy plate of the present invention has an equivalent circle diameter. Is 0.3 to 4 μm, and the number density of the intermetallic compound containing Cu is preferably 1 × 10 ⁴ pieces / mm ² or more. When the intermetallic compound containing Cu has a circle-equivalent diameter of less than 0.3 μm or a number density of less than 1 × 10 ⁴ pieces / mm ² , the formability is good, but the β phase ( This is because sufficient suppression of precipitation of Al ₃ Mg ₂ ) at grain boundaries cannot be obtained, and stress corrosion cracking tends to decrease. Moreover, it is because there exists a tendency for press formability to deteriorate that the equivalent circle diameter of the intermetallic compound containing Cu exceeds 4 μm. For this reason, it is preferable that a circle equivalent diameter is 0.3-4 micrometers, and the number density of the intermetallic compound containing Cu is 1 * 10 < ⁴ > piece / mm < ² > or more. In addition, although the upper limit of the number density of the intermetallic compound containing Cu is not particularly limited, it is preferably 7 × 10 ⁵ pieces / mm ² from the viewpoint of press formability. Furthermore, the equivalent circle diameter and number density of the intermetallic compounds present in the aluminum alloy plate should be measured by analyzing the observation photographs obtained by observing thin film samples prepared from the aluminum alloy plate with a transmission electron microscope. Can do. Whether the precipitate to be observed is an intermetallic compound containing Cu or an intermetallic compound not containing copper is determined by using an elemental analyzer equipped in a transmission electron microscope. It can be identified by conducting an elemental analysis of the precipitate. Furthermore, the equivalent circle diameter and the number density of the intermetallic compound containing Cu and the intermetallic compound not containing copper are the manufacturing conditions (treatment or processing) in which the solid solution state or precipitation state of the intermetallic compound changes, such as heat treatment during the production. Therefore, it can be controlled by manufacturing an aluminum alloy plate by a manufacturing method described later.

(III) Manufacturing Method of Aluminum Alloy Plate of the Present Invention Next, a preferred embodiment of the manufacturing method of the aluminum alloy plate of the present invention will be described below.
In the method for producing an aluminum alloy plate according to the present invention, it is particularly important to control the cooling rate from the time when the ingot is homogenized and the start temperature of the subsequent hot rolling to an appropriate range.

  First, an aluminum alloy having the above component composition is melted according to a conventional method, and a normal casting method such as a continuous casting method or a semi-continuous casting method is appropriately selected and cast. And the obtained ingot is preferably homogenized at a first temperature in the range of 490 to 580 ° C, more preferably 500 to 570 ° C. If the first temperature is less than 490 ° C, segregation of additive elements formed during casting may not be eliminated, and sufficient formability may not be obtained. If the first temperature exceeds 580 ° C, eutectic melting may occur during processing. This is because it may occur and cracks may occur during hot rolling. The treatment time of the homogenization treatment is not particularly limited, and can be in the range of 0.5 hours to 24 hours, for example.

  Next, after subjecting the ingot to the homogenization treatment, the average cooling rate is within a range of 430 to 500 ° C., preferably within a range of 440 to 490 ° C. and to a second temperature lower than the first temperature. More preferably, after cooling so that the average cooling rate measured at the 1/4 thickness position of the ingot is in the range of 500 to 3000 ° C./h, hot rolling is performed at the second temperature. To start. Here, the formation of an intermetallic compound containing Cu has an effect of improving the stress corrosion cracking resistance, while the formation of an intermetallic compound not containing Cu has an action of reducing the stress corrosion cracking resistance. However, when the average cooling rate exceeds 3000 ° C./h, formation of an intermetallic compound containing Cu tends to be hindered and the stress corrosion cracking resistance tends to be reduced, and the average cooling rate is 500 ° C./hour. If it is less than h, the formation of an intermetallic compound containing no Cu is promoted and the stress corrosion cracking resistance tends to be lowered. Here, the measurement position of the average cooling rate is set to “1/4 thickness position” because the temperature history at the 1/4 thickness position has a great influence on the performance of the material. Further, the reason for limiting the second temperature to the range of 430 to 500 ° C. is that if the second temperature is less than 430 ° C., there is a possibility that a biting failure may occur during hot rolling, and the second temperature is 500 ° C. If it exceeds, cracks may occur during hot rolling. For this reason, in this invention, after giving said homogenization process to an ingot, an average cooling rate is 500-3000 degrees C / h in the range of 430-500 degreeC and 2nd temperature lower than 1st temperature. After cooling to be within the range, hot rolling is started at the second temperature.

  After the hot rolling, winding is performed at a third temperature within a range of 320 to 380 ° C., preferably within a range of 340 to 360 ° C., and then cold rolling and final annealing are sequentially performed. The reason for limiting the coiling temperature to the third temperature in the range of 320 to 380 ° C. is that if the third temperature is less than 320 ° C., a recrystallized structure cannot be obtained after hot rolling, and surface defects (rolling) This is because, when the third temperature exceeds 380 ° C., the crystal grains become coarse after hot rolling and rough skin may occur.

  The above description shows only some embodiments of the present invention, and various modifications can be made in the claims.

Examples of the present invention will be described below.
An aluminum alloy having the composition shown in Table 1 was melted and agglomerated by DC casting. The obtained ingot (thickness 30 mm, width 175 mm) was heated to 560 ° C. (first temperature) and held at this first temperature for 4 hours, and then the ingot was moved from the first temperature to the second shown in Table 2. The temperature range up to the temperature is cooled at the average cooling rate shown in Table 2 and held at the second temperature for 15 minutes, and then hot rolling is started at the second temperature (hot rolling start temperature), and a 4 mm thick plate material It was. The coiling temperature (third temperature) after hot rolling was 360 ° C. Next, this plate was cold-rolled to a thickness of 1 mm, then heated in a salt bath furnace at 540 ° C. for 30 seconds, and subjected to a softening treatment (final annealing treatment) that forced air cooling to near room temperature with a fan. . Through the above steps, aluminum alloy plates of Examples and Comparative Examples were manufactured.

(Test method)
[Measurement method of crystal grain size]
About each produced said aluminum alloy plate, the crystal grain diameter was measured. As a method of confirmation, a sample was taken from the center of the width of the aluminum alloy plate, the crystal grain structure was photographed on the rolled surface, and 5 lines in the vertical and horizontal directions were linearly spaced at a 3 mm × 3 mm field of view. The crystal grain size was measured by the intercept method, and the average value of the measured crystal grain sizes was calculated as the average crystal grain size (μm). In this example, a crystal grain size of less than 50 μm was accepted, and a crystal grain size of 50 μm or more was rejected (rough skin was generated).

[Calculation method of number density of intermetallic compound]
About each produced said aluminum alloy plate, the center part of the cross section parallel to a rolling surface is measured from the center part of plate | board width using the transmission electron microscope (TEM) by the magnification of 10,000 times using JEM-2010 by JEOL. ). The area of the intermetallic compound in the obtained image was measured using image analysis software “Winroof”, and was a value evaluated by a diameter (equivalent circle diameter) when converted to a circle equivalent. Whether or not the compound contains Cu was analyzed using EDS (Energy Dispersive X-ray Spectroscopy). Number density of intermetallic compounds not containing Cu having an equivalent circle diameter of 0.1 to 0.5 μm (number / mm ² ) and number density of intermetallic compounds containing Cu having an equivalent circle diameter of 0.3 to 4 μm (Pieces / mm ² ) was obtained. Observation was performed in three fields of view, and an average value was adopted.

[Tensile properties]
About each produced said aluminum alloy plate, the JIS5 test piece was cut out in the direction orthogonal to a rolling direction, and tensile strength (MPa), yield strength (MPa), and elongation at break (%) were measured by the tension test. In this example, those having a tensile strength of 240 MPa or more were accepted, those having a tensile strength of less than 240 MPa were rejected, and those having a tensile strength of 100 MPa or more were accepted, and those having a tensile strength of less than 100 MPa were rejected.

[Press formability]
In order to investigate press forming, an overhang forming test and a draw forming test were conducted.
In the overhang forming test, a square blank having a side of 120 mm is cut out from the center of the width of each of the aluminum alloy plates produced above, and then wrinkled by a punch with a diameter of 50 mm using a die with a bead by an Eriksen tester. The test was performed under the conditions of a holding force of 40 kN and a molding speed of 2.0 mm / s, and the limit overhang height (mm) at which no crack was generated was measured, and the press formability was evaluated from the measured value of the overhang height.
In the deep drawability test, a disk with a diameter of 110 mm is formed from each of the aluminum alloy plates produced above, and a low-viscosity lubricating oil is applied as a test material. Using an Erichsen tester, a lock bead is provided on the die. First, a flat head punch with a diameter of 50 mm is used under the conditions of a wrinkle restraining force of 10 kN and a molding speed of 2.0 mm / s, and the limit drawing height (mm) at which cracks do not occur is measured. The moldability was evaluated.
In this example, the evaluation of the press formability is as follows. In the stretch formability, the overhang height of 17 mm or more is accepted, and less than 17 mm is rejected. In addition, the deep drawability is drawn. Of 15 mm or more was accepted, and less than 15 mm was rejected.

[Stress corrosion cracking resistance]
The stress corrosion cracking resistance is obtained by subjecting a specimen taken from the center of the width of each of the aluminum alloy sheets produced above to cold rolling at a processing rate of 30%, followed by a sensitization treatment in which heat treatment is performed at 120 ° C. for 7 days. The chromic acid solution (pure water 1) was heated to 95 ° C. in a stress-loaded state in which the sensitized test piece was bent into a U shape with a bending radius of 2 mm and 3 mm, and both ends of the U shape were restrained. 1 liter of CrO ₃ : 36 g, aqueous solution containing K ₂ Cr ₂ O ₇ : 30 g and NaCl: 3 g), measure the time until stress corrosion cracking occurs, cracking within 2 hours at a bending radius of 2 mm The case where the crack occurred was indicated as “×”, the case where no crack occurred in 24 hours was designated as “◯”, and the case where no crack occurred in 96 hours was designated as “◎”.
Table 3 shows the evaluation results of the tensile properties, press formability, and stress corrosion cracking resistance of the aluminum alloy sheet produced in this example.

  From the evaluation results shown in Table 3, each of Invention Examples 1 to 23 has a high tensile strength of 240 MPa or more, an overhang height of 17 mm or more, a drawing height of 15 mm or more, and excellent stress corrosion cracking resistance. It was. On the other hand, Comparative Examples 22 to 31 having a composition outside the proper range of the present invention and Comparative Examples 32 to 39 produced under production conditions outside the proper range of the present invention are all tensile properties, press formability and resistance. At least one of the stress corrosion cracking properties was inferior.

  Since the aluminum alloy plate of the present invention has high strength, good press formability and excellent stress corrosion cracking resistance, it is particularly useful for members used in various automobiles represented by automobile body sheets and body panels. In addition to parts, it is suitable for use in materials and parts used in ships, aircraft, etc., building materials, structural materials, other various machinery and equipment, home appliances and parts, and its industrial value. Is big.

Claims (7)

  In mass%, Si: 0.03-0.35%, Fe: 0.03-0.35%, Mg: 3.0-5.0%, Cu: more than 0.09% and less than 0.50% and An aluminum alloy plate characterized by containing Mn: more than 0.05% and not more than 0.35%, with the balance being composed of Al and inevitable impurities. ^2. The aluminum alloy according to claim 1, wherein the circle-equivalent diameter is 0.1 to 0.5 μm, and the number density of intermetallic compounds not containing Cu is 1 × 10 ⁶ pieces / mm ² or less. Board. 3. The aluminum alloy according to claim 1, wherein the circle equivalent diameter is 0.3 to 4 μm, and the number density of the intermetallic compound containing Cu is 1 × 10 ⁴ pieces / mm ² or more. Board.   The aluminum alloy sheet according to any one of claims 1 to 3, wherein Cu: 0.13 to 0.35 mass%.   5. The composition according to claim 1, wherein the composition further contains one or two of Ti: 0.05% by mass or less and B: 0.05% by mass or less. Aluminum alloy plate. A method for producing the aluminum alloy plate according to any one of claims 1 to 5,
The ingot obtained by casting the aluminum alloy material having the above composition is subjected to a homogenization treatment at a first temperature within a range of 490 to 580 ° C, and then within a range of 430 to 500 ° C and the first temperature. After cooling to an average cooling rate within a range of 500 to 3000 ° C./h to a lower second temperature, hot rolling is started at the second temperature, and then 320 to 380 ° C. A method for producing an aluminum alloy sheet, comprising winding up at a third temperature within the range, followed by sequentially performing cold rolling and final annealing. The first temperature is in the range of 500 to 570 ° C;
The second temperature is within a range of 440 to 490 ° C;
The said 3rd temperature exists in the range of 340-360 degreeC, The manufacturing method of the aluminum alloy plate of Claim 6 characterized by the above-mentioned.