JP2745254B2 - Aluminum alloy hard plate excellent in local overhang property and method of manufacturing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hard aluminum plate for forming used as a can body for deep drawing in a can body of an aluminum can or a lid material of a can, and a method for producing the same. The present invention relates to an aluminum alloy hard plate having high strength and excellent local overhang and bendability, and a method for producing the same.

[0002]

2. Description of the Related Art Generally, as a lid material for an aluminum can,
Despite its high strength, it has good formability in deep drawability, overhang performance and bending workability.
No. 5000 alloys such as 5082 alloy and 5182 alloy are used. In particular, since the internal pressure is applied to the lid material of cans for beer and other carbonated beverages, since the strength after baking coating is required to be high strength of 300 N / mm ² or more, 5182 alloy is mainly used. I have.

[0003]

In the above-mentioned process of manufacturing the can lid material, 240 to 350 called a coil coat is used.
A baking coating is performed at a relatively high temperature of about 5 to 30 seconds at a temperature of about 5 ° C. for a short time. Therefore, there is a demand for a material that hardly causes a decrease in strength due to the baking coating or a manufacturing method that can overcome the decrease in strength. In addition, as the performance as a can lid, it is required that local overhanging performance is good, such as dimple processing and rivet molding, and that bending cracks do not occur when opening the lid in the case of the easy open end of the pull tab.

5182, which is the mainstream of the above-mentioned alloys for can materials
In the case of the alloy, since the strength is greatly reduced in the baking coating, the reduction in strength has been compensated by increasing the initial strength by increasing the cold rolling reduction. However, in order to increase the initial strength by increasing the cold reduction ratio, local overhang performance deteriorates, such as dimple processing and rivet molding, and in the case of the easy open end of the pull tab, bending at the time of opening the lid Insufficient performance in terms of cracking. To reduce the cost of can materials in the future, thinner and higher strength can materials are required.
It is becoming difficult to respond within the range of the manufacturing method. In order to solve these problems, an object of the present invention is to provide an aluminum alloy hard plate having high strength after baking and excellent in formability and a method for producing the same.

[0005]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies on alloying elements and manufacturing methods in order to solve the above-mentioned problems. As a result, it is necessary to improve aging to reduce the decrease in strength after baking. It has been found that the above object can be achieved by reducing dislocations and fine insoluble intermetallic compounds that inhibit dislocation movement, which are factors that inhibit the flow of material during molding. Specifically, the present invention is configured as follows.

[0006] The alloy plate according to the first aspect of the present invention is characterized in that Mg3.
0-6.0 wt%, Cu 0.15-0.5 wt% , Fe
It is essential to contain 0.05 to 0.6 wt% and Si <0.3 wt% , Mn 0.05 to 0.6 wt% , Cr
<0.3 wt%, Zr <0.3 wt%, V <0.3 wt
%, One or more of Zn <0.5 wt%, and Mn + Fe + Cr + Zr + V <1.0 wt%
In the and balance substantially alloy whose aluminum and impurities, that the to that station BuCho Desei wherein a longitudinal diameter intermetallic compounds of the following insoluble 0.5μm is 400 [mu] m ² per 800 or less It is an excellent aluminum alloy hard plate. Further, the manufacturing method of the invention according to claim 2 is characterized in that
3.0-6.0 wt%, Cu 0.15-0.5 wt% ,
Fe0.05~0.6wt%, Si <and mandatory by containing 0.3wt%, Mn0.05~0.6wt%,
Cr <0.3 wt%, Zr <0.3 wt%, V <0.3
wt., one or more of Zn <0.5 wt.%, and Mn + Fe + Cr + Zr + V <1.0 w
The alloy containing t and the balance substantially consisting of aluminum and impurities was subjected to DC casting, followed by heating at 500 to 580 ° C. for 2 hours or more, followed by rolling according to a conventional method.
After heating to a temperature in the range of 400 to 580 ° C. at a heating rate of 1 ° C./sec or more, immediately or after holding for a short time within 120 sec, intermediate annealing for cooling at a cooling rate of 1 ° C./sec or more is performed. by subjecting the final cold rolling in the above reduction ratio, station characterized in that the longitudinal direction of the diameter of the intermetallic compounds of the following insoluble 0.5μm to obtain a plate is 400 [mu] m ² per 800 or less BuCho This is a method for producing an aluminum alloy hard plate excellent in output. The production method of the invention of claim 3, wherein the claim in 2 method described before Symbol final cold 100 ° C. after the rolling / hr and heated to a temperature in the range of 100 to 200 ° C. in the following heating rate 30 min a method for producing superior aluminum alloy hard plate that station BuCho Desei be characterized by applying final annealing to hold more. Hereinafter, in the present invention,% of the alloy component means wt%, and 0.5 μm indicating the size of the intermetallic compound.
Means a value in the longitudinal diameter.

[0007]

First, the reasons for limiting the range of the component composition of the raw aluminum alloy in the present invention will be described. The alloying element in the aluminum hard plate for molding of the present invention mainly increases the strength of the base aluminum alloy, suppresses softening during baking, and facilitates appropriate control of fine intermetallic compound size. It is added. Mg; Mg coexists with Cu; P. zone,
The precipitation process of S′Al ₂ CuMg and SAl ₂ CuMg contributes to the improvement of strength and the age hardening in the precipitation stage of the intermediate phase. Further, Mg alone contributes to solid solution strengthening. As described above, it is an indispensable element for improving the strength. However, if the amount of Mg is less than 3 wt%, the strength required for the lid material of the internal pressure container cannot be obtained. On the other hand, when the amount of Mg exceeds 6%, it hardens workability due to excessive work hardening, and significantly impairs the rollability during hot rolling. Therefore, the amount of Mg is 3 ~
It was within the range of 6%. Cu; Cu itself contributes to solid solution strengthening similarly to Mg, and Al during the baking treatment.
-An element that contributes to improvement in strength after baking coating by age hardening due to precipitation of Cu-Mg based precipitates. When the Cu content exceeds 0.5 wt%, age hardening is easily obtained, but excessive hardening impairs the formability. Therefore, the upper limit of the Cu content is set to 0.5 wt%. On the other hand, if the content is less than 0.15%, the effect is small.
%. Si: Si generally has an effect of contributing to age hardening by precipitating a Mg ₂ Si-based compound by coexistence with Mg. However, in an alloy system having a high Mg content, a large intermetallic compound is easily generated, so that formability is high. Significantly inhibits If the amount of Si is less than 0.3%, the effect is relatively small, so the amount of Si is set to less than 0.3% by weight. Mn; M
n not only contributes to the strength improvement but also has the function of improving the high temperature strength. Mn coexists with Fe,
i is generated in the form of an Al (Mn, Fe) Si-based insoluble compound, and thus has the effect of reducing the generation of Mg ₂ Si. If the Mn content is less than 0.05%, there is no effect. Of the above compounds, fine compounds having a diameter in the longitudinal direction of 0.5 μm or less significantly impair aging and formability as described later, but when the Mn content exceeds 0.6%, the Al (M
The amount of the fine compound of 0.5 μm or less in the n, Fe) Si-based insoluble compound increases. Therefore, the Mn content is 0.05 to 0.6.
wt%. Fe; Fe is an element required to promote the precipitation of Si together with Mn and reduce the generation of Mg ₂ Si. When the Fe content is less than 0.05 wt%, the effect is small, and when the Fe content exceeds 0.6 wt%, the amount of fine compounds of 0.5 μm or less of the Al (Mn, Fe) Si-based insoluble compound coexists with Mn. More. Therefore F
The e content was in the range of 0.05 to 0.6 wt%. In addition, Cr, Zr, V, and Zn all have a Cr content of less than 0.3 wt%, a Zr content of less than 0.3 wt%, a V content of less than 0.3 wt%, and a Zn content of less than 0.5 wt%. If so, it contributes to the improvement in strength without losing the effect of the present invention. But M
When n, Fe, Cr, Zr, and V coexist, a fine insoluble compound is formed in the aluminum matrix. Therefore, the total amount of these elements is Mn + Fe + Cr + Zr + V.
<1.0 wt%.

The balance of each of the above components may be Al and impurities. In ordinary aluminum alloys, a small amount of Ti alone or a combination of Ti and B may be added in order to refine the ingot crystal grains. In the present invention, a small amount of Ti or Ti and B may not be contained. Permissible. However, when Ti is added, the amount of addition is 0.1.
If the content is less than 01 wt%, the effect of refining the ingot crystal grains cannot be obtained, while if it exceeds 0.2 wt%, primary TiAl ₃ is crystallized to inhibit the formability.
It is preferable to be within the range of 0.2 wt%. Also Ti
When B is added together with B, if the amount of B added is less than 1 ppm, there is no effect, and if it exceeds 500 ppm, coarse particles of TiB ₂ are mixed and formability is impaired.
It is preferable to be within the range of 500 ppm.

In the aluminum alloy hard plate for forming according to the present invention, not only the composition of each alloy component is regulated as described above, but also the dispersion state of the intermetallic compound in the state of the final rolled sheet is appropriately adjusted. Very important. That is, as described in the claims, it is necessary that the number of insoluble intermetallic compounds of 0.5 μm or less is 800 or less per 400 μm ² . This is schematically shown in FIG. By setting such an intermetallic compound in a dispersed state, the following effects can be obtained. a) Originally, the hardening phenomenon due to aging precipitation is such that an extremely fine precipitate 2 such as a GP zone precipitates in an aluminum matrix as shown in FIG. However, when the insoluble intermetallic compound 1 is present in the structure, the ultrafine precipitate is preferentially precipitated on the insoluble compound in a heat treatment corresponding to aging such as baking of paint, contributing to the strength. Disappears, resulting in insufficient curing. In particular, an insoluble intermetallic compound having a size of 0.5 μm or less tends to become a precipitation nucleus of an aging precipitate such as Al ₂ CuMg. In the present invention, by defining the number of insoluble intermetallic compounds of 0.5 μm or less as 800 or less per 400 μm ^2, the amount of the aging precipitates dispersed and present in the aluminum matrix increases, thereby improving the strength and suppressing the softening. Effect is increased. b) When the Al-Cu-Mg-based compound, which is an aging precipitate, is present in the aluminum matrix, it exhibits age hardening properties in which the movement of dislocations is pinned to increase the strength, and dislocations are observed in the heat history of baking coating and the like. Has the effect of suppressing softening due to the recovery of dislocation. Therefore, in order to prevent softening in baking coating, it is necessary to precipitate a large amount of aging precipitates in the matrix. c) In addition, when the amount of the intermetallic compound increases, the flow of the material is hindered at the time of forming, and the formability is deteriorated such as the occurrence of bending cracks at the time of bending or the deterioration of local overhanging property. Therefore, in this respect, it is desirable that the amount of the intermetallic compound is small.

Next, a method for producing the aluminum hard plate for forming according to claim 2 will be described. First, a melt of an alloy having the above-described alloy composition is DC-cast. Then, soaking or heating at 500 to 580 ° C for 2 hours or more is performed. 0.5 μm produced in the alloy composition of the present invention
The following insoluble intermetallic compounds are mainly precipitates generated during the heating stage of the ingot. The precipitation of the fine insoluble intermetallic compound of 0.5 μm or less progresses most in the vicinity of 450 to 500 ° C., and at a temperature higher than 500 ° C., the fine precipitate forms a solid solution and is relatively coarse in equilibrium. Precipitates in the form of an intermetallic compound, and as a result, fine precipitates are reduced, and coarse ones are further enlarged and spheroidized. Therefore, 0.5 μm
In order to reduce the following intermetallic compounds, the temperature is kept at 500 ° C. or more and for 2 hours or more. On the other hand, when the temperature exceeds 580 ° C., partial melting starts, which is not preferable in operation. From this, the condition of soaking or heating is 500-580 ° C.
The holding time is 2 hours or more. After soaking or heating, hot rolling and cold rolling are performed according to a conventional method to obtain a required intermediate plate thickness. At this time, depending on the required sheet thickness, cold rolling may not be performed, and only hot rolling may be performed. Thereafter, when the heating rate and the cooling rate are 1 ° C./sec or more, the ultimate temperature is 400 to 58.
By performing intermediate annealing at 0 ° C. and a holding time of 0 to 2 min to make an alloy component contributing to age hardening such as Cu into a solid solution state, and subsequently introducing dislocations by cold rolling, during final annealing or baking coating processing Al ₂ which is an aging precipitate
CuMg or the like precipitates and softening can be suppressed. In this intermediate annealing, if the ultimate temperature is lower than 400 ° C., the above-mentioned effects cannot be obtained. On the other hand, if the temperature is higher than 580 ° C., partial melting occurs and it is difficult to perform annealing with ordinary equipment such as CAL (continuous annealing furnace). Become. Further, since the annealing is performed at a high temperature, the heating rate and the cooling rate are set to 1 ° C./sec or more and the holding time is 2
Within a minute, there are few obstacles. Further, the cooling rate is preferably higher in order to prevent re-precipitation of the element once dissolved. In particular, Mn-based precipitates sufficiently start to precipitate even at a temperature of about 300 ° C. in a state where dislocations exist as in the case of intermediate annealing. Therefore, as described in the present invention, in order to reduce the amount of intermetallic compounds having a size of 0.5 μm or less, it is necessary to carry out rapid heating and rapid cooling at a high temperature for a short time as described above. After the intermediate annealing, final cold rolling at a rolling reduction of 30% or more is performed. Unless the cold rolling reduction is 30% or more, the desired strength cannot be obtained. The coil winding temperature after cold rolling was 110 ° C.
It is preferable to set the following. Temperature after coil winding is 11
At a temperature of 0 ° C. or higher, the temperature temporarily rises due to friction between the inside and the cold roll during cold rolling, and dislocation recovery occurs before aging precipitation, so that it is difficult to obtain sufficient final strength. Therefore, if the cold rolling is completed at a temperature lower than 110 ° C. where the recovery speed is relatively slow, the strength decreases little.

Although a sufficient effect can be obtained even if the final annealing is not carried out, in order to obtain a material having a higher strength, it is desirable to use a third embodiment.
As described, the ultimate temperature is 1 at a heating rate of 100 ° C / hr or less.
It is desirable to perform final annealing at 00 to 200 ° C. for a holding time of 30 minutes or more. By performing this final annealing, the strength can be increased, and when the strength is not so much required, the cold working rate can be reduced correspondingly, and improvement in formability can be expected. Since the baking coating of the can lid is a relatively high-temperature and short-time treatment, the Al-Cu-Mg based G.I.
P. Zone, the presence of S ′ phase precipitates,
This has the effect of pinning the recovery of dislocations during heating during the baking coating process to suppress softening. For this reason, it is desirable to perform final annealing as preliminary aging. When the temperature reaches a high temperature in a short time as the annealing condition, the recovery is prioritized over the precipitation, so that the strength cannot be improved. Therefore, the heating rate is set to 10 in order to precipitate by aging from the point of relatively slow recovery rate at the time of temperature rise.
The temperature may be 0 ° C./hr or less. In order to sufficiently perform aging precipitation, the ultimate temperature must be 100-200 ° C. and the holding time must be 30 minutes or more. Specifically, by performing the final annealing, the proof stress after the paint baking treatment is up to 20N.
/ Mm ² .

In the aluminum hard plate thus obtained, the insoluble intermetallic compound having a size of 0.5 μm or less was observed in a 3,000-fold visual field by a TEM.
A texture of 800 or less per 00 μm ² is obtained. The aluminum hard plate for forming having the composition ratio of the alloy component and the dispersed state of the intermetallic compound according to the present invention by the above-described manufacturing method and the like has a necessary strength after painting and baking necessary as a material used for a lid or the like for an easy-open can. Is 5182 of the conventional material
It is equal to or more than an alloy, and has much better formability, especially bending property and local overhang property than conventional materials. Therefore, it becomes a molding material that can reduce the thickness and weight of the can lid as compared with the related art.

[0013]

Embodiments of the present invention will be described below. Table 1 shows the composition ratio of the alloy components.
Is within the component composition range defined in the present invention, and the alloy of production code F is the Mn composition range and Mn + F
The total amount of e + Cr + Zr + V deviates from the definition of the present invention, and the alloy of manufacturing code G corresponds to the 5182 alloy.

[0014]

[Table 1]

Table 2 shows the production conditions and the number of insoluble compounds having a size of 0.5 μm or less as specified in the present invention. The production process shown in Table 2 was applied to each alloy shown in Table 1 to obtain a rolled plate having a final plate thickness of 0.3 mm. In manufacturing, the proof stress value of the production code G of 300 N which is a conventional example
/ Mm ² , the cold rolling reduction is adjusted. The production codes A, B, C, F, and G are obtained by changing the conditions within the range of the production method of the present invention, and the production code D has a lower heating rate during the intermediate annealing than the production conditions of the present invention. The production code E had a lower soaking temperature than that of the present invention, and was manufactured in the same manufacturing process as the production code C under other conditions. G is a conventional example. That is, A is the present invention that conforms to the manufacturing conditions of claim 2, B is the one that has been subjected to final annealing according to the present invention, and that complies with the conditions of claim 3, and C is the same as B according to the present invention. D: Cold rolling reduction of 50% D: Comparative example in which heating rate during intermediate annealing was slow E: Comparative example with low soaking temperature F: Comparative example with different alloy composition G is a conventional example in which a 5182 alloy was manufactured under the manufacturing conditions described in the present invention.

[0016]

[Table 2]

Table 3 shows the results of examining the performance of the material thus obtained. Performance is 275
Each material was subjected to a paint baking treatment corresponding to a heat history of 20 ° C. × 20 sec, and mechanical properties, bending properties, local overhang property evaluation, and Erichsen test were performed. In the bending test, the bending radius was set to １ ／ of the plate thickness in the direction in which the bending line was in the rolling direction.
(In the example, 0.15 mm), a 180 ° bending was performed, and the evaluation was made based on the evaluation of cracks on the bending surface. Rank evaluation: 1: No crack 2: Crack of crack level 3: Crack is found 4: Crack is found in the whole area In the local overhang test, the diameter φ = 2 mm and the radius of curvature of the tip R
Using a punch 4 of = 1 mm, the test material 6 was placed on a die 5 and local extrusion press molding was performed. The test value was evaluated by setting the length of the punch 4 to 1.0
The distance was changed from 10 mm to 1.9 mm in 10 steps at intervals of 0.1 mm, and the punch length, which was one step shorter than the punch length at the stage where cracks occurred, was indicated as the limit at which cracks did not occur. For example, when cracks occurred at the stage of punch length = 1.5 mm, the local overhang test value was indicated as 1.4 mm. Therefore, it can be evaluated that the larger the value of the test value, the better the local overhang formability.

[0018]

[Table 3]

As can be seen from Table 3, when the alloy composition ratio according to the present invention is made into a dispersed state of the intermetallic compound specified in the present invention, the strength is sufficient and the formability such as bendability is remarkably improved. Good ones have been obtained. And, according to the production method of claim 2 or claim 3 of the present invention, the above-mentioned dispersed state of the intermetallic compound can be obtained. On the other hand, even if the alloy composition ratio of the present invention is the conventional manufacturing method, the dispersion state of the intermetallic compound is different from that of the present invention. There is only. Even under the production conditions of the present invention, when the composition ratio of the alloy is different from that of the present invention, there is no sufficient strength and formability, which is equivalent to that of the conventional technology. Hereinafter, each will be described. C is the best alloy composition, cold rolling condition and final annealing method in the present invention, and has sufficient strength such as tensile strength and proof stress, and also has a bendability rank, Erichsen, local overhang, etc. A remarkably good quality was also obtained. A is an example of the invention, but does not perform final annealing on C. In order to obtain the same strength as the invention example of C, the cold rolling reduction must be increased, and the performance is slightly inferior. However, the results are excellent as compared with the conventional example G. B is an example of the invention, but the cold-rolling temperature is higher than that of C. In order to obtain the same strength as that of the invention of C, the cold rolling reduction has to be increased. Although slightly inferior, the results were excellent as compared with Conventional Example G. In D, the heating rate during intermediate annealing was reduced for comparison with the present invention, and the cold rolling reduction was increased in order to match the proof stress, and the number of intermetallic compounds was out of the range of the present invention. The performance was inferior to G. E is the one obtained by changing the soaking conditions as compared with Invention Example C. In this case the number of the following insoluble compounds 0.5μm becomes large as 1500/400 [mu] m ² as shown in Table 2, the results in proof stress by detail the operational effect 5N / mm ² lower, further bending or the like of The performance was about the same as the conventional example. F has a higher Mn content among the components although the production method is within the scope of the present invention as compared with the invention examples. The number of this case 0.5μm or less insoluble compounds has become large as 2000/400 [mu] m ² as shown in Table 2, although the strength can be obtained sufficient strength even at low rolling reduction As a result, the moldability such as bending property was inferior to the conventional example. G is a conventionally used 5182 alloy manufactured under the manufacturing conditions described in the present invention. However, the strength is 10 N / mm ² lower than that of the inventive example, and the formability such as bendability is significantly lower. As described above, intermetallic compounds of the alloy composition and 0.5μm or less insoluble according to the present invention is 400 [mu] m ²
In the case of a hard aluminum plate in a dispersed state of not more than 800 pieces per one, it is possible to obtain a material having much better strength and formability than before. Further, in the material of the present invention, if the formability such as the bending property is not required to be equal to that of the conventional material, it is possible to obtain a high-strength material by further increasing the cold rolling reduction. That is, a high-strength material corresponding to a reduction in the thickness of the can material can be obtained.

[0020]

As described in detail above, by appropriately adjusting the dispersing state of the intermetallic compound in the state of the final rolled sheet in the range of the component composition of the aluminum alloy according to the present invention, the strength after baking of the coating can be reduced. An aluminum alloy hard plate which is equal to or higher than the 5182 alloy, which is a material, and which is excellent in moldability, particularly bendability and local overhangability, and which is particularly excellent for can lid materials and the like, is obtained. Therefore, as a material used for a lid or the like for an easy-open can, it becomes a molding material that can reduce the thickness and weight of the can lid as compared with the related art.
According to the production method of the second aspect of the present invention, the dispersed state of the intermetallic compound can be easily and stably obtained in quality. In addition, when the final annealing is performed as described in claim 3, the strength can be further increased, and when the strength is not so much required, the cold working rate can be reduced by that amount. Formability can be improved. Specifically, by performing the final annealing, the proof stress after the paint baking treatment is up to 20 N / m.
m ₂ can be increased. Therefore, it is preferable to perform final annealing.

[Brief description of the drawings]

FIG. 1 is a diagram showing a dispersion state of a compound in an example of the present invention.

FIG. 2 is a cross-sectional view showing a local overhang test method in an example of the present invention.

[Explanation of symbols]

Reference Signs List 1 Insoluble compound of 0.5 μm or less 2 Al-Cu-Mg-based precipitate that has been aged and deposited on insoluble compound 3 Al-Cu-Mg-based precipitate that has been aged and deposited in a matrix 4 Punch 5 Die 6 Test material

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI C22F 1/00 686 C22F 1/00 686B 691 691A 691B 691C 692 692A 694 694A

Claims (3)

(57) [Claims] 1. Mg 3.0 to 6.0 wt%, Cu 0.1
5 to 0.5 wt% , Fe 0.05 to 0.6 wt%, Si
<0.3 wt% , Mn 0.0
5 to 0.6 wt% , Cr <0.3 wt%, Zr <0.3
wt.%, V <0.3 wt.%, Zn <0.5 wt.%, and Mn + Fe + Cr +
Zr + V <1.0 wt%, with the balance being substantially aluminum and impurities, having a longitudinal diameter of 0.5
8 μm / 400 μm ²
Aluminum alloy hard plate having excellent to that station BuCho Desei wherein the 00 pieces or less. 2. Mg 3.0 to 6.0 wt%, Cu 0.1
5 to 0.5 wt% , Fe 0.05 to 0.6 wt%, Si
<0.3 wt% , Mn 0.0
5 to 0.6 wt% , Cr <0.3 wt%, Zr <0.3
wt.%, V <0.3 wt.%, Zn <0.5 wt.%, and Mn + Fe + Cr +
Zr + V <1.0 wt%, the balance being substantially aluminum and impurities, 500 to 500% after DC casting.
After heating at 580 ° C. for 2 hours or more, and then rolling according to a conventional method, heating at 40 ° C. at a heating rate of 1 ° C./sec or more.
Immediately after heating to a temperature in the range of 0 to 580 ° C or 1
After holding for a short time within 20 sec, intermediate annealing for cooling at a cooling rate of 1 ° C./sec or more is performed, and final cold rolling is performed at a rolling rate of 30% or more, so that the diameter in the longitudinal direction is 0.5 μm or less. 400μ of insoluble intermetallic compound
It and obtaining a m ² per 800 less is plate
Excellent production method of an aluminum alloy hard plate to station BuCho Desei. 3. A method according to claim 2, wherein, before Symbol final cold 100 ° C. / hr or less in the heating rate after the rolling 100
Method for producing an aluminum alloy hard plate having excellent to that station BuCho Desei characterized by applying final annealing to hold to 200 DEG ° C. range temperature in a heated 30 minutes or more of.