KR101310497B1 - Aluminum alloy plate and manufacturing method for the same - Google Patents

Abstract

An object of the present invention is to provide an aluminum alloy plate which can suppress yellow color development as much as possible even when subjected to anodizing with a sulfuric acid bath, and which is colored in a pale green-white system which does not have a red color, and a manufacturing method thereof.
In mass%, Mg 2.0 to 3.0%, Cr 0.15 to 0.25%, Ti 0.005 to 0.20% or Ti 0.005 to 0.20% and B 0.0005 to 0.05%, the remainder is composed of Al and unavoidable impurities, When Si is 0.15% or less, Fe is 0.4% or less, Mn is 0.06% or less, and the Cr content is T _CR % and the high capacity of Cr is S _CR %, P _CR = T _CR -S _CR ≤0.065 % Aluminum alloy plate. The ingot composed of the above composition is hot rolled after the homogenization treatment, and after the cold rolling, the annealing is performed at an intermediate temperature annealing temperature and temperature rate of 100 ° C / sec or more, and the annealing is stabilized at 100 ° C / sec or more after cold rolling. The manufacturing method of the aluminum alloy plate to perform.

Description

Aluminum alloy plate and its manufacturing method {ALUMINUM ALLOY PLATE AND MANUFACTURING METHOD FOR THE SAME}

The present invention relates to an aluminum alloy plate whose anodized film is light green, and a method for producing the same.

The Al-Mg-based alloy sheet is intermediately annealed in the process of making the sheet, and cold rolled and annealed to impart desired mechanical properties. However, since the alloy of this system is softened naturally and the strength is not stabilized after cold working, stabilization annealing may be performed after cold rolling if necessary.

The aluminum alloy plate is anodized by a sulfuric acid bath so that the surface has a color tone peculiar to the alloy, and is used for interior and exterior panels for building, articles, home appliances, electric and electronic devices such as digital cameras and PCs. For example, JIS5052 alloy plates with low residual strain and good processing accuracy in non-heat treated alloys develop a yellowish tint by anodizing with a sulfuric acid bath. This color tone is considered to be caused by Cr in the alloy added for recrystallization and the like, and in the case of dislike yellow, an aluminum alloy plate without Cr has been published.

Japanese Patent Application Laid-Open No. 9-143602 discloses an Al-Mg-based alloy plate containing 0.10 to 0.30% of Mn containing Cr as 0.02% or less as an impurity.

Japanese Patent Application Laid-open No. Hei 9-143602

This invention is an Al-Mg type alloy plate, and Cr is added and contained for recrystallization refinement | miniaturization. However, when Cr is contained, a strong yellow color is obtained by anodizing with a sulfuric acid bath, and an aluminum alloy plate which develops white color is not obtained, and thus the use of the plate is limited.

That is, an object of the present invention is to provide an aluminum alloy plate which can suppress yellow color development as much as possible even when subjected to anodization treatment by a sulfuric acid bath, and which is colored in a pale green-white system which does not have a red color, and a manufacturing method thereof.

The inventors have obtained the knowledge that yellow color development in the Al-Mg type alloy plate containing Cr is based on the Cr containing intermetallic compound produced | generated in the plate making process containing casting, and completed this invention.

That is, this invention is as follows (1)-(4).

(1) containing 2.0 to 3.0 mass% of Mg, 0.15 to 0.25 mass% of Cr, 0.005 to 0.20 mass% of Ti or 0.005 to 0.20 mass% of Ti and 0.0005 to 0.05 mass% of B; When Si in the said impurity is 0.15 mass% or less, Fe is 0.4 mass% or less, Mn is 0.06 mass% or less, and when the content of the Cr is T _CR mass% and the high capacity of Cr is S _CR mass%, -S _CR a _CR value in the _CR P, aluminum alloy sheet, characterized in that _CR P ≤0.065% by weight.

(2) An aluminum alloy plate having an anodized film, wherein a sulfuric acid anodized film is coated on the aluminum alloy plate of the above (1).

(3) An ingot formed of the composition of the above (1) base material is hot rolled after homogenization treatment, and in all annealing treatments after subsequent cold rolling, the temperature raising and lowering rate are 100 ° C./sec or more. Method of manufacturing the plate.

(4) A method for producing an aluminum alloy plate with an anodized film, characterized by coating a sulfuric acid anodized film of 3 to 12 µm on an aluminum alloy plate obtained by the method of the above (3).

That is, this invention provides the manufacturing method of (1) aluminum alloy plate suitable for sulfuric acid anodizing, (2) aluminum alloy plate provided with sulfuric acid anodizing, (3) aluminum alloy plate suitable for sulfuric acid anodizing, ( 4) Provided is a method for producing an aluminum alloy plate having a sulfuric acid anodizing film.

In the Al-Mg alloy plate containing Cr of the present invention, the amount of the intermetallic compound containing Cr is less than or equal to a predetermined value. Since it is an alloy plate, the selection range of a hue becomes wider, and it has an effect that it can be used for the housing | casings, such as interior and exterior panels for building which favors a white system, a thing, household appliances, electrical and electronic equipment, such as a digital camera and a PC. Moreover, the manufacturing method of the said alloy plate has the effect which can provide easily the board which has the said effect by the technical application of the grade which accelerates the temperature-fall temperature-fall rate at the time of engraving.

In the present invention, the reason for limiting the chemical composition will be described.

<Mg: 2.0 to 3.0 mass%>

Mg is a main element of the JISA5xxx-based alloy, and is an element for sufficiently giving strength only by work hardening. If less than the lower limit, Mg is insufficient in strength when processed with a panel or a base.

In the Al-Mg alloy containing only Mg, the color tone of the surface becomes light gray by the sulfuric acid electrolytic bath-based anodization treatment.

<Cr: 0.15 to 0.25 mass%>

Cr is an element for miniaturizing recrystallized grains during intermediate annealing of JISA5xxx-based alloys, and the effect is insufficient at lower than the lower limit, and if the upper limit is exceeded, Cr is strongly yellowed by the anodizing treatment even if the upper limit is exceeded.

<Ti: 0.005 to 0.20 mass%> or

<Ti: 0.005 to 0.20 mass% and B: 0.0005 to 0.05 mass%>

Ti or Ti and B are elements for miniaturizing the cast structure and effectively preventing cracking of the ingot at the time of casting. Ti alone may be added, but when Ti and B are added in combination, the refinement performance of the cast structure is improved. Ingot cracking prevention performance at the time of casting improves. If the content is less than the lower limit, respectively, the effect of miniaturization is small and the crack prevention performance of the ingot is deteriorated. When the upper limit is exceeded, a coarse intermetallic compound of Al-Ti or Ti-B is crystallized and impairs workability and formability of the plate. The content of Ti or Ti and B can be appropriately selected by adjusting the addition of one or two or more of the selection of the return material and the Ti metal, the Al-Ti mother alloy or Al-Ti-B.

<Inevitable impurities>

Inevitable impurities refer to elements other than the alloy elements Mg, Cr, Ti (or Mg, Cr, Ti, and B) that are intentionally added, and in a conventional solvent method, now, return materials, master alloys, and tool tools. It is said that it is inevitable that is mixed from. However, in the present invention, when the amount of unavoidable impurities is increased, it is necessary to limit the color of the element, thereby deteriorating the color of the pale green white, which suppresses the characteristic yellow color of the present invention. That is, Si with a large influence is 0.15 mass% or less, Fe is 0.4 mass% or less, and Mn is 0.06 mass% or less. Other unavoidable impurities include Zn of 0.25% by mass or less, and Cu of 0.1% by mass or less, preferably 0.05% by mass or less. It is preferable to regulate other elements to 0.05 mass% or less, respectively.

<T _CR -S _CR = P _CR ≤0.065 mass%>

Here, T _CR is the content (mass%), S is _CR amount (mass%) of Cr in the high dose (mass%), P _CR of Cr intermetallic compound of Cr, by T = P _{CR CR CR} -S Is represented.

Yellow is a compound represented by Cr-containing intermetallic compounds, for example, Al ₇ Cr, Al ₁₁ Cr, Al ₁₈ Cr ₂ Mg ₃ , and the like. I think.

<< Analysis of Employment Cr >>

Al content is dissolved in hot phenol, and Cr in solution is analyzed by IPC emission spectrometry to quantify solid solution Cr (S _CR ). Since the value of S _CR is obtained by this method, the value of T _CR -S _CR = P _CR , that is, the value of Cr amount (P _CR mass%) in the intermetallic compound can be calculated from the Cr content (T _CR ).

<< mechanism of yellow color suppression >>

The value of P _CR is the amount of Cr present as a compound, and the larger the value of P _CR is, the larger the amount of Cr-containing compound is. I think that. When this P _CR value is 0.065 mass% or less, it can be considered that the amount of Cr-containing compound is small, and therefore, the amount of light having a yellow wavelength is small and yellow can be suppressed.

Next, the preferable manufacturing method of the aluminum alloy plate of this invention is demonstrated.

Preferred manufacturing methods of the invention include the following steps.

<1> The ingot is hot rolled after the homogenization treatment, and the final annealing treatment is performed after the subsequent cold rolling.

<2> The ingot is hot rolled after the homogenization treatment, followed by intermediate annealing treatment after the subsequent cold rolling, followed by cold rolling, and final annealing. The intermediate annealing treatment can be performed multiple times.

<3> The ingot is hot rolled after the homogenization treatment, followed by intermediate annealing treatment after the subsequent cold rolling, and then cold rolled. The intermediate annealing treatment can be performed multiple times.

<4> The ingot is hot rolled after the homogenization treatment, followed by intermediate annealing treatment after the subsequent cold rolling, followed by cold rolling, and stabilization annealing treatment. The intermediate annealing treatment can be performed multiple times.

<5> The ingot is hot rolled after the homogenization treatment and then temper annealed after the subsequent cold rolling.

<6> The ingot is hot rolled after the homogenization treatment, followed by intermediate annealing treatment after the subsequent cold rolling, followed by cold rolling, and temper annealing treatment after cold rolling. The intermediate annealing treatment can be performed multiple times.

In the aluminum alloy sheet according to the present invention, the color tone of the anodic oxide film under the present invention composition is L ^* value of 75 to 95, a ^* value of -0.8 to 0, and b ^* value of 0 to 2.0 is novel. Although manufacturing conditions are not limited, In order to deepen understanding of a technical relationship, an example of the most preferable manufacturing method is shown as follows.

The process of <1> is further demonstrated.

The molten alloy of the composition of the present invention is preferably cast through a filter by a semi-continuous casting method (DC casting) or the like after the solvent to obtain a ingot for rolling. The surface of the ingot is preferably 5 or more to about 20 mm to remove the non-uniform layer of the ingot surface layer portion, and is heated and maintained at 440 to 560 ° C. for about 1 to 24 hours or more for homogenization heat treatment. In the case of the multistage homogenization treatment, at least a high temperature step may satisfy the above temperature conditions. This treatment reduces or eliminates local micro segregation such as segregation of β phase (Mg ₂ Al ₃ ) and other Cr.

Next, hot rolling is performed to a thickness of about 2 to 10 mm. An alloying element is precipitated as a fine intermetallic compound in the course of this hot rolling, recrystallization refine | miniaturizes in a final annealing process, and color is made uniform by a subsequent anodization process.

The process of <2> is further demonstrated.

The rolling plate which finished hot rolling similarly to the process of <1> is cold-rolled by a conventional method, performs an intermediate annealing, softens it, and makes it O material (annealed aluminum material), and then rolls a rolling rate. Cold rolling is carried out to form a plate of required thickness, and then final annealing is performed. The intermediate annealing treatment may be performed a plurality of times.

The process of <3> is further demonstrated.

As in the process of <1>, the rolled plate which has finished hot rolling is subjected to cold rolling by the conventional method, softened by intermediate annealing, and made of O material. Then, the rolling rate is cold rolled to determine the required mechanical properties. Grant. The intermediate annealing treatment may be performed a plurality of times.

The process of <4> is further demonstrated.

Since Al-Mg type | system | group alloy softens naturally after cold working and is not stable, when a stable material can be obtained, it stabilizes after final cold rolling. That is, like the process of <1>, the rolled plate which finished hot rolling is cold-rolled by a conventional method, it softens by carrying out intermediate annealing, it is made into O material, and finally cold-rolls and stabilizes annealing. The intermediate annealing treatment may be performed a plurality of times.

The process of <5> is further demonstrated.

In the Al-Mg alloy, if the composition and the cold rolling ratio are known, the mechanical properties can be predicted by determining the heating conditions after cold rolling. In rolling, the cold rolling rate is determined and rolled, and after the rolling, a temper annealing treatment is performed.

The process of <6> is further demonstrated.

Since Al-Mg type alloy can predict a mechanical property by setting heating conditions after cold rolling, if a composition and cold rolling rate are known, the plate which finished hot rolling similarly to the process of <1> is cold-rolled by the conventional method. After rolling, the intermediate annealing is carried out to soften to O material, the cold rolling rate is determined and rolled, and after the said rolling, an annealing process is carried out. The intermediate annealing treatment may be performed a plurality of times.

The temperature raising and temperature lowering rate conditions of this intermediate annealing, final annealing, stabilizing annealing and crude annealing are important for obtaining the color tone of the present invention. That is, it is to suppress the precipitation of the intermetallic compound containing Cr as much as possible. The conditions of this intermediate annealing or final annealing are made into O material by hold | maintaining for 1 to 100 second at the temperature of 370-500 degreeC. In the case of the stabilization annealing treatment after the intermediate annealing, depending on the degree of imparting strength, after the cold rolling, the stabilization annealing is performed by holding at a temperature of 150 to 250 ° C. for 1 to 100 seconds. When the cold rolling rate is determined and cold rolled, and the temper annealing treatment is performed after the rolling, the conditions vary depending on the mechanical properties finally obtained. After cold rolling, the temper annealing is maintained at a temperature of 250 to 370 ° C. for 1 to 100 seconds. The process is performed.

Here, the manufacturing method of this invention is characterized by the following necessarily (A) performed necessarily or (B) or (C) performed as needed.

<Rapid temperature and rapid temperature drop during intermediate annealing, final annealing, stabilization annealing and temper annealing>

(A) The intermetallic compound containing Cr generated in the temperature raising and lowering process, with the temperature rising to the temperature range of the intermediate annealing, final annealing, or both annealing and the temperature-fall rate up to 100 ° C or higher, being at least 100 ° C / sec. Prevents precipitation and prevents coarsening.

(B) Cr is generated in the temperature raising and lowering process in the same manner as in (A) above with the temperature rising to the stabilizing annealing temperature range and the temperature-falling rate up to 100 ° C or higher performed as required above. It suppresses the precipitation of the intermetallic compound to contain and prevents coarsening thereof.

(C) The metal containing Cr which arises in the temperature rising and temperature-falling process similarly to (A) mentioned above with the temperature rising to the said crude | annealing annealing process temperature range, and the temperature-fall rate to 100 degreeC or more. It inhibits the precipitation of liver compounds and prevents their coarsening.

These annealing treatments can be performed by raising the temperature using, for example, an electromagnetic induction heating furnace and lowering the temperature by water cooling.

The aluminum alloy plate obtained by annealing by the rapid temperature increase and rapid temperature fall which satisfy | fills all the conditions of said (A) or (B) or (C) implemented as needed is a metal containing Cr in the subsequent anodizing process. Yellow color development by the liver compound can be suppressed, and color development can be carried out by pale greenish white without yellowing.

In addition, hot rolling and cold rolling may be performed as a separate process as mentioned above, and may be performed as a consistent process continuously from a hot rolling temperature area | region to a cold rolling temperature area | region. In the case of the latter hot / cold integrated process, in the cold rolling temperature range, all the matters concerning the cold rolling apply.

<Condition of Anodic Oxidation>

The aluminum alloy plate according to the present invention is provided for anodizing treatment with a sulfuric acid bath. Although the conditions are not limited, The most preferable conditions are as follows. That is, since rolling oil is used in the rolling process at the time of engraving, it is usually immersed in the acidic aqueous solution containing about 3-20 mass% of nitric acid in order to remove the adhesion oil of a plate surface. In order to remove the oxide on the surface and to form an anodized film uniformly in the subsequent anodization by a sulfuric acid bath, the rolled plate from which oil is removed is alkaline aqueous solution containing about 5-30 mass% of caustic soda after washing with water. It is immersed in the inside, and it etches and removes several micrometers of surface layers. The rolled sheet etched by the alkali treatment is a sulfuric acid bath containing 10 to 30% by mass of sulfuric acid after washing with a rolled sheet as an anode, and has a cathode current density of 0.5 to 5 A / dm ² , preferably 1 to 3 A /. in dm ^2, and electrolysis thereby yokon conduct electrolytic treatment from 5 to 30 ℃, preferably from 10 to 30 ℃, delivery time 10 to 120 minutes, and the resulting 3 to 12㎛ as film thickness. In this film thickness range, when expressed according to the display method by UCS, the film color tone is colored with light green suppressed light yellow with L ^* value 75-95, a ^* value-0.8-0.0, b ^* value 0-2.0. A naturally colored film is obtained.

<Thickness of the anode oxide film: 3 to 12 µm>

If the thickness of the anodic oxide film is less than 3 µm, the corrosion resistance and scratch resistance are insufficient. On the contrary, if the thickness of the anodic oxide film exceeds 12 µm, the yellow color becomes strong, and a preferable light green white is not obtained. Therefore, the thickness of the anodic oxide film is limited to the range of 3-12 micrometers.

<Tint after anodizing>

The display method of the color tone after anodizing is by UCS, and this UCS is prescribed by JISZ8729 and JISZ8730. That is, JISZ8729 describes the object color display method by the L ^* a ^* b ^* color system and Luv colorimeter, and JISZ8730 is described by the color difference display method.

The L ^* value shown in JISZ8730 represents the brightness, and the higher the value, the brighter the color tone. a ^※ value, b ^※ value indicates color, and when it is red, a ^※ value becomes higher and smaller than 0 becomes green. On the other hand, when yellowish, b ^* value increases, and when it becomes smaller than 0, it becomes blue. The color tone obtained by the sulfuric acid bath of the aluminum alloy plate of this invention is L ^* value 75-95, a ^* value is -0.8-0, b ^* value is 0-2.0, It is the light green white which suppressed yellow as much as possible.

[First Embodiment]

It demonstrates further using the board manufactured by the process of said <2>.

The alloy molten metal of the composition shown in Table 1 was passed through a filter, and the rolling ingot of thickness 560mm was obtained by DC casting. The surface of this ingot was 10 mm faced, hold | maintained at the temperature of 440 degreeC for 2 hours, heated again, it was kept at the temperature of 540 degreeC for 4 hours, and it was homogenized.

Then, the hot rolling of each ingot started at the temperature of 530 degreeC, and it rolled to thickness 8mm. The temperature of the hot rolled sheet at the end of hot rolling was 360 ° C.

The 8 mm rolled sheet was cold rolled to 3 mm. The 3 mm plate was changed to an elevated temperature and a temperature-fall rate up to 100 ° C., held at a temperature of 425 ° C. for 10 seconds, and annealed to an O material.

Next, it cold-rolled to thickness 1mm (rolling ratio 67%). The 1 mm plate was heated for 10 seconds at a temperature of 425 ° C by varying the temperature and rate of temperature drop to 100 ° C for final annealing.

Next, flatness was taken out through the tension leveler, cut into 100 mm x 100 mm to obtain a sample for the next anodized film treatment.

Anodizing process is as follows.

The surface of each sample was wash | cleaned and degreased with the organic solvent, it was immersed by dipping in the liquid temperature of 50 degreeC and 8% caustic soda water solution for 2 minutes, it was immersed in water temperature 20 degreeC, 10 mass% nitric acid aqueous solution for 1 minute, and neutralized. Thus, each sample pretreated in this way was then divided | divided into bath temperature 18 degreeC, 15 mass% sulfuric acid bath, current density of 1 A / dm <^2> , and processing time, and produced the oxide film of various thickness. After washing with water, it was sealed by drying in hot water at 95 ° C and dried. Subsequently, color tone was measured by the MINOLTA CM508i apparatus. The results are shown in Table 2.

From the results of Table 2, even if Cr is contained in the Al-Mg alloy within the specified range, the temperature increase rate and the temperature decrease rate of the intermediate annealing and the final annealing treatment are both above the prescribed speed (sample numbers 2-1 and 2-2). , And the present invention example of Fig. 2) shows that the color tone of the anodic oxide film is pale green white in which yellow is suppressed. On the other hand, for comparison with much higher than the amount of Cr than the specified range (Sample Nos. 2-4) is, it can be seen that the temperature elevation and temperature lowering speed may be both longer than the specified speed value is also high P _CR with a strong yellowish gray.

Moreover, it turns out that green and yellow develop strongly in the comparative example (film thickness of 15 micrometers of sample numbers 2-1, 2-2, and 2-3) which set the film thickness to 15 micrometers exceeding a prescribed range.

In addition, even if the chemical composition is an example of the present invention, when any one of the temperature increase and the temperature decrease rate is slower than the prescribed range (Sample Nos. 2-5 and 2-6), it is found that the _PCR value is also high and yellow is a strong gray color. Can be.

[Second Embodiment]

It demonstrates further using the board manufactured by the process of said <4>.

The alloy molten metal of the composition shown in Table 1 was passed through the filter, and the DC casting method was performed, and the rolling ingot of thickness 560mm was obtained. The surface of this ingot was 10 mm faced, hold | maintained at the temperature of 440 degreeC for 2 hours, heated again, it was kept at the temperature of 540 degreeC for 4 hours, and it was homogenized.

Then, hot rolling of each ingot was started at the temperature of 530 degreeC, and it rolled to thickness 6mm. The temperature of the hot rolled sheet at the end of hot rolling was 360 ° C.

The 6 mm rolled sheet was cold rolled to 1.5 mm. The 1.5 mm plate was changed to a temperature increase rate and a temperature decrease rate up to 100 ° C., respectively, and maintained at a temperature of 425 ° C. for 10 seconds to anneal intermediate to obtain O material.

Next, it cold-rolled to thickness 1mm (rolling ratio 33%). The 1 mm plate was stabilized and annealed by varying the temperature rising rate and the temperature drop rate to 100 ° C for 10 seconds at a temperature of 220 ° C.

Next, the film was flattened through a tension leveler, cut into 100 mm x 100 mm, and subjected to anodization in the same manner as in the first embodiment. Thereafter, color tone was measured in the same manner as in the first example. The results are shown in Table 3.

From the results of Table 3, even if Cr is contained in the Al-Mg alloy in the specified range, the temperature increase and temperature decrease rates of the intermediate annealing and stabilization annealing treatment are both above the specified speed (sample numbers 3-1 and 3-2). , And the present invention in 3 to 3) shows that the color tone of the anodic oxide film is pale green white in which yellow is suppressed.

On the other hand, for comparison with much higher than the amount of Cr than the specified range (Sample Nos. 3-4) is, it can be seen that the temperature elevation and temperature lowering speed may be both longer than the specified speed value is also high P _CR with a strong yellowish gray.

In addition, it turns out that green and yellow color strongly develop in the comparative example (film thickness of 15 micrometers of sample numbers 3-1, 3-2, and 3-3) which made the film thickness more than 15 micrometers exceeding a prescribed range. .

In addition, even if the chemical composition is the present invention, it is found that when either one of the temperature increase and the temperature decrease rate is slower than the prescribed range (Sample Nos. 3-5 and 3-6), the _PCR value is high and yellow is a strong gray color. Can be.

Further, within the prescribed ranges produced by the processes described in the above <1>, <3>, <5> and <6> other than <2> and <4> demonstrated in the first and second embodiments. As for the aluminum alloy sheet of the composition, during all annealing treatments after cold rolling, the temperature and temperature reduction rate are 100 ° C / sec or more, whereby the color tone after anodization within the prescribed range is defined as L ^* value, a ^* value, and b in the prescribed range. ^{* The} value was obtained, and it was confirmed visually that pale green-white without yellow was obtained.

Third Embodiment

In the 1 mm plate after cold rolling of Sample No. 3-2 produced under the conditions of the second example, the mechanical properties of the plate on the first day after the cold rolling and the plate on the tenth day without performing the stabilization annealing after the cold rolling and The mechanical properties of the plate on the first day after the stabilization annealing and the plate on the tenth day that were subjected to stabilization annealing after cold rolling were measured. The results are shown in Table 4.

From the results in Table 4, the mechanical properties of the stabilized annealing plate (Sample No. 4-2) are stable even after 10 days, whereas the mechanical properties of the non-stabilizing annealing plate (Sample No. 4-1) It can be seen that even after 10 days, the fluctuation is greatly changed.

According to the present invention, there is provided an aluminum alloy plate which can suppress yellow color development as much as possible even when subjected to anodizing with a sulfuric acid bath and which is colored in a pale green-white system that does not have a red color, and a method of manufacturing the same.

Claims (6)

It contains 2.0 to 3.0 mass% of Mg, 0.15 to 0.25 mass% of Cr, and 0.005 to 0.20 mass% of Ti, and is composed of the remainder Al and the unavoidable impurities, 0.15 mass% or less of Si in the impurities, and 0.4 mass% or less of Fe. When Mn is 0.06 mass% or less and the content of Cr is T _CR mass% and the high capacity of Cr is S _CR mass%, the value P _CR of T _CR -S _CR is P _CR ≤0.065 mass%. An aluminum alloy plate, characterized in that. Mg 2.0 to 3.0% by mass, Cr 0.15 to 0.25% by mass, Ti 0.005 to 0.20% by mass and B 0.0005 to 0.05% by mass, which is composed of the remainder Al and inevitable impurities, and the Si in the impurities is 0.15% by mass or less this, when the content of the Fe to 0.4 mass%, Mn less than 0.06% by mass of Cr and the high capacity of the% by weight T _{CR, CR} S Cr in mass%, the value of T -S _{CR CR CR} P, An aluminum alloy plate, characterized in that P _CR? 0.065 mass%. The aluminum alloy plate of Claim 1 or 2 is coat | covered with 3-12 micrometers of sulfuric acid anodizing films, The aluminum alloy plate with anodizing film characterized by the above-mentioned. It contains 2.0 to 3.0 mass% of Mg, 0.15 to 0.25 mass% of Cr, and 0.005 to 0.20 mass% of Ti, and is composed of the remainder Al and the unavoidable impurities, 0.15 mass% or less of Si in the impurities, and 0.4 mass% or less of Fe. The ingot which consists of a composition which makes Mn 0.06 mass% or less is hot-rolled after a homogenization process, and in all the annealing treatments after subsequent cold rolling, temperature rising and temperature-fall rate are 100 degreeC / sec or more, The aluminum characterized by the above-mentioned. Method for producing an alloy plate. Mg 2.0 to 3.0% by mass, Cr 0.15 to 0.25% by mass, Ti 0.005 to 0.20% by mass and B 0.0005 to 0.05% by mass, which is composed of the remainder Al and inevitable impurities, and the Si in the impurities is 0.15% by mass or less , Hot rolled the ingot composed of a composition having Fe of 0.4% by mass or less and Mn of 0.06% by mass or less after homogenization treatment, and in all annealing treatments after subsequent cold rolling, the temperature raising and temperature lowering rates were 100 ° C / sec or more. The manufacturing method of the aluminum alloy plate characterized by the above-mentioned. The aluminum alloy plate obtained by the manufacturing method of the aluminum alloy plate of Claim 4 or 5 is coat | covered with a sulfuric acid anodizing film 3-12 micrometers, The manufacturing method of the aluminum alloy plate with anodizing film characterized by the above-mentioned. .