JP2001098338A - High strength and high formability aluminum alloy sheet with excellent recrystallization grain refinement during high temperature annealing - Google Patents

Abstract

(57) [Summary] [Problem] Al capable of forming ultra-fine grains having a recrystallized grain size of 5 μm or less even after high-temperature recrystallization annealing.
It is intended to provide a -Mg-based Al alloy plate. SOLUTION: Mg: 3.0 to 10.0%, Mn: 0.1 to 1.5%, the balance being Al and unavoidable impurities, the reduction of 90% or more is applied in cold rolling, and the recrystallized grain size after final annealing is reduced. In Al-Mg-based Al alloy sheets with a size of 5 μm or less, the maximum length of Al-Mn-based
It should be less than 500nm.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high-strength and high-formability aluminum alloy sheet (hereinafter, aluminum is simply referred to as Al) excellent in refining recrystallized grains during high-temperature annealing.

[0002]

2. Description of the Related Art Mainly as transportation equipment such as railway vehicles, aircrafts, ships, automobiles, motorcycles and bicycles, or chemical plants such as pressure vessels and tanks, and also as structural members and structural parts such as buildings and structures. , AA to JIS 5052, 5056, 508
Al-Mg-based to 5000-based Al alloy sheets containing 3.5% (% by mass, the same applies hereinafter) of Mg, such as 2, 5182, 5083, and 5086, are used. These Al-Mg-based Al alloy sheets having a high Mg content have excellent strength and formability and good weldability, and thus are widely used as welded structural members.

[0003] As is well known, the Al-Mg-based Al alloy sheet is subjected to a recrystallization annealing after a homogenizing heat treatment of the ingot, a hot rolling and a cold rolling to a predetermined thickness, in a usual manner. Al
It is an alloy plate. The recrystallized grain size of the Al-Mg-based Al alloy sheet is usually at a level of 20 to 30 µm.

On the other hand, in recent years, to further improve the strength and formability of the Al-Mg-based Al alloy sheet, studies have been made to further refine the recrystallized grain size. For example, Japanese Patent Application No. 11
-268599, etc., contain up to 7.0% Mg, Fe: 0.1-2.0%, Cr: 0.05-0.5%, Zr: 0.05-
For Al-Mg-based Al alloys containing 0.2% or more of one or more types, apply a large reduction of 90% or more in cold rolling to reduce the recrystallized grain size after recrystallization annealing to 5μm or less. It has been proposed.

In this technique, the Mg content is extremely increased, and a large reduction is applied in the cold rolling to increase the number of dislocations and Fe-containing compound particles serving as nucleation sites for recrystallization. The purpose is to suppress the coarse growth of recrystallized grains due to the movement of grain boundaries by using dispersed particles (precipitates) such as Cr and Zr.

[0006]

According to the recrystallized grain refining technique, the recrystallized grain size after recrystallization annealing is actually reduced to 5 μm.
The following ultrafine-grained Al-Mg-based Al alloy sheets can be manufactured. However, in this recrystallized grain refinement technology, the recrystallization annealing temperature is set to 350 ° C. in order to reduce the recrystallized grain size to 5 μm or less.
The following low temperature is required. In other words, if the recrystallization annealing temperature is set to a temperature exceeding 350 ° C., the recrystallized grains become coarse and the grain size cannot be reduced to 5 μm or less.

In this recrystallization grain refinement technique, the Mg content is extremely increased, and a large reduction is applied during cold rolling, so that the work hardening amount of the Al alloy sheet is extremely large.
For this reason, if the temperature during the recrystallization annealing is restricted to a lower temperature side, annealing may be insufficient, and the formability such as elongation and drawing height required in the above various applications may not be satisfied. There is.

In this respect, Japanese Patent Application No. 11-268599 also discloses that the final annealing temperature must be as low as 350 ° C. or less.
%, Fe: 1.26%, Cr: 0.15%, when the final annealing temperature is 420 ° C., the recrystallized grain size is lower than that of the invention example having an annealing temperature of less than 350 ° C. It is described that the average grain size exceeds 5 μm and the properties such as formability of the Al alloy sheet are deteriorated.

Therefore, in this recrystallized grain refining technique, the annealing temperature must be lower than 350 ° C. in order to make the recrystallized grain size after recrystallization annealing smaller than 5 μm. For this reason, depending on the application, the strength is too high or Al
In some cases, the required formability may not be satisfied, such as the generation of SS marks specific to -Mg-based Al alloy sheets, and the applications of the Al alloy sheets may be restricted.

The present invention has been made in view of such circumstances, and has as its object to reduce the recrystallized grain size after annealing to ultra-fine grains of 5 μm or less even after high-temperature recrystallization annealing. It is an object of the present invention to provide an Al-Mg-based Al alloy sheet that can be used.

[0011]

In order to achieve this object, the gist of the Al-Mg-based Al alloy sheet of the present invention is as follows: Mg: 3.0 to 10.0%
(% By mass, the same applies hereinafter), Mn: 0.1 to 1.5%, the balance consisting of Al and unavoidable impurities, a reduction of 90% or more is applied in cold rolling, and the recrystallization grain size after final annealing is 5 μm or less. In the Al-Mg-based Al alloy plate, the maximum length of the Al-Mn-based compound dispersed and precipitated in the structure is set to 500 nm or less.

Further, as another embodiment of the Al alloy sheet of the present invention to which the selective addition element is added, the Al alloy sheet further comprises Fe: 0.1
~ 2.0%, Cr: 0.05 ~ 0.2%, Zr: 0.05 ~ 0.2% containing one or more of (corresponding to claim 2), and / or
Contains one or two types of Ti: 0.001-0.1%, B: 1-300ppm
(Corresponding to claim 3).

A preferable use of the Al alloy sheet of the present invention is that it is used for final annealing at a high temperature exceeding 350 ° C. (corresponding to claim 4).

The present invention is based on the technical idea of Japanese Patent Application No. 11-268599. That is, while increasing the Mg content, a large reduction is applied in cold rolling to increase the dislocations that serve as nucleation sites for recrystallization, and further reduce Fe compound particles (crystallized products) that serve as nucleation sites. Increase, and M
The technical idea of suppressing the coarse growth of recrystallized grains due to the movement of grain boundaries by using compound particles (precipitates) such as n, Cr, and Zr and reducing the recrystallized grain size after final annealing to 5 μm or less is described in the above-mentioned patent application. flat
Same as 11-268599. Therefore, in the present invention,
It is premised that essential addition of Mn to be described later and that the Al alloy sheet is cold-rolled at a large rolling reduction of 90% or more.

[0015] However, the present inventors first added the compound particles or dispersed particles (precipitates) such as Mn, Cr, and Zr, which should suppress the coarse growth of recrystallized grains due to the movement of the grain boundaries, to the temperature of 350 ° C.
It was found that a difference in the effect of refining the recrystallized grain size (preventing coarsening) occurs during the above-described high-temperature recrystallization annealing, which does not occur during the low-temperature recrystallization annealing at less than 350 ° C.

That is, as is well known, compound particles such as Mn, Cr, and Zr are generated during the homogenizing heat treatment of the Al-Mg-based Al alloy ingot. However, the size and shape of the compound particles, in particular, differ depending on the respective contents, casting conditions, and conditions during the homogenization heat treatment, and this leads to the refinement of the recrystallization grain size during recrystallization annealing at 350 ° C or higher (coarse Prevention) leads to a difference in effectiveness.

In particular, compound particles such as Cr and Zr are usually smaller than the size of Mn compound particles. Therefore, it is generally thought that the effect of suppressing the growth of crystal grains is larger in compound particles such as Cr and Zr than in Mn compound particles.

On the other hand, compound particles such as Cr and Zr also have the effect of reducing the number of nucleation sites. If this effect is large, the shape of crystal grains is not spherical and equiaxed, but in the rolling direction. It becomes elongated grains that are elongated. The elongated grains tend to become coarser, especially during recrystallization annealing at a high temperature of 350 ° C. or higher. Therefore, this result indicates that the recrystallized particle size of the compound particles such as Cr and Zr and the compound particles of Mn can be reduced.
(Prevention of coarsening) It is presumed that this leads to a difference in effect.

Therefore, compound particles such as Cr, Zr, etc.
At the time of recrystallization annealing at a low temperature of less than 0 ° C., the effect of refining the recrystallized grain size is exhibited, but at the time of recrystallization annealing at a high temperature of 350 ° C. or more, the effect of refining the recrystallized grain size becomes weak. As a result,
Although the recrystallized grain size of the Al-Mg-based Al alloy sheet after the final annealing can be reduced to a fine grain size less than the normal recrystallized grain size of 20 to 30 μm, the ultra-fine grain size of 5 μm or less which is the main object of the present invention is And cannot be done.

In the case where the Mn compound particles are coarsened, particularly, during recrystallization annealing at a high temperature of 350 ° C. or more,
The present inventors have also found that the effect of refining the recrystallized particle size of the Mn compound particles themselves is weakened. Therefore, the present inventors considered that the critical size of the coarsening of the Mn compound particles and the effect of refining the recrystallized grain size is that Al-Mg dispersed and precipitated in the crystal grains of the Al-Mg-based Al alloy plate. The maximum length of the compound is 500 nm
The present invention has been made by further understanding the following.

[0021]

BEST MODE FOR CARRYING OUT THE INVENTION (Al-Mn-based compound particles) The Al-Mn-based compound particles referred to in the present invention are MnAl ₆ when Fe or Si is not contained, and when they contain Fe or Si. Contains (Fe, Mn) ₃
Compounds such as SiAl ₁₂ and (Fe, Mn) Al ₆ .

In the present invention, the maximum length of the Al-Mn-based compound particles is specified to be 500 nm or less. When the maximum length of the Al-Mn-based compound particles exceeds 500 nm,
Due to the fine dispersion of Al-Mn-based compound particles in the Al alloy structure, the effect of refining the recrystallized grain size during recrystallization annealing at 350 ° C. or higher is weakened. As a result, although the recrystallized grain size of the Al-Mg-based Al alloy sheet after the final annealing can be reduced to a fine grain of the ordinary recrystallized grain size of 20 to 30 μm or less, the recrystallization grain size of 5 μm or less which is the main object of the present invention is obtained. Ultrafine particles cannot be obtained.

The maximum length of the Al-Mn-based compound particles is Al-Mn
Although it depends on the shape of the Al-Mn-based compound particles, it is the length of the longest part among the shapes of the Al-Mn-based compound particles. For example, Al-Mn
In the case where the system compound particles are plate-shaped, the maximum side length is applicable, and in the case where the system compound particles are granular, the maximum diameter length is applicable.

The measurement and identification (verification) of the maximum length of the Al-Mn-based compound particles is carried out by observation with a transmission electron microscope (TEM) of 10,000 times or more of the Al alloy structure. In the transmission electron microscope measurement, the thickness of the observation part was locally reduced to 0.1 to 0.3 μm by electropolishing (jet polishing) using a measurement sample thinned to a thickness of about 0.1 mm by mechanical polishing.
(1000-3000Å) The thinned part is observed by TEM. Then, the maximum length of the Al-Mn-based compound particles that can be measured in each visual field is measured, and the maximum length of the compound particles per visual field is averaged in 10 visual fields.

The recrystallized grain size of the Al alloy plate is measured by a cutting method using an optical microscope and a scanning electron microscope (SEM). More specifically, draw a straight line so that the number of crystal grains cut by a straight line is 100 or more, and divide the length of this straight line by the number of cut crystal grains to obtain a recrystallized grain size. .

(Chemical Composition of the Al Alloy of the Present Invention) Next, the chemical composition of the Al alloy of the present invention will be described.

(Amount of each element in Al alloy of the present invention) Mg: 3.0 to 10.0%. Mg provides the strength and formability necessary for the structural material to the Al alloy sheet by solid solution strengthening, suppresses recovery during cold rolling under large pressure, and refines the recrystallized grain size after final annealing. It is an essential element. If the content of Mg is less than 3.0%, solid solution strengthening is not sufficient, and furthermore, recovery during cold rolling under large pressure cannot be suppressed, making it difficult to refine the recrystallized grain size after final annealing. As a result, required strength and moldability are insufficient.
On the other hand, if the content exceeds 10.0%, it becomes difficult to produce a sheet itself by casting or hot rolling, and edge cracks during cold rolling under a large pressure increase, which is suitable for industrial production. Disappears. Therefore, the content of Mg is 3.0-1.
The range is 0.0%.

Mn: 0.1 to 1.5% Mn, as described above, forms fine Al-Mn-based compound particles and refines the recrystallized grain size after recrystallization annealing at 350 ° C. or higher (after final annealing). In particular, it is an element necessary for ultrafineness with a recrystallized grain size of 5 μm or less. Mn content 0.1%
If less than the amount of Al-Mn-based compound particles formed in the structure
(Number) is insufficient and the recrystallized grain size after final annealing at a high temperature of 350 ° C. or more cannot be reduced to an ultra-fine size of 5 μm or less.
On the other hand, when the content of Mn exceeds 1.5%, the effect of refining crystal grains is saturated, and the elongation and formability of the Al alloy sheet are rather reduced by the compound particles. Therefore, the content of Mn is in the range of 0.2 to 1.5%.

Fe: 0.1-2.0%, Cr: 0.05-0.2%, Zr: 0.05
~ 0.2%. Fe, Cr and Zr are the same elements in that they have the effect of making the recrystallized grain size finer after recrystallization annealing.

Fe forms Al-Fe-based compound particles (crystals), becomes a nucleation site during recrystallization annealing (after final annealing), and exerts the effect of refining the recrystallization particle size. Element. If the content is less than 0.1%, this effect is insufficient, while 2.0%
On the other hand, if it exceeds, the formability, elongation, etc. of the Al alloy sheet after recrystallization annealing are reduced. Therefore, the content of Fe is set in the range of 0.1 to 2.0%.

Cr and Zr are, like Mn, Al-Cr based, Al
-Zr-based compound particles that form the same particles and have the effect of refining the recrystallized grain size after recrystallization annealing (after final annealing). As described above, these recrystallized grains have a recrystallized grain size of 5 μm after final annealing at a high temperature of 350 ° C. or more.
Although it does not have the effect of reducing the particle size to less than m, during recrystallization annealing at a low temperature of less than 350 ° C., it exerts a refining effect of reducing the recrystallized grain size after annealing to 5 μm or less. Therefore, in the case of selective inclusion, Mn is required, and in addition to this,
Use a combination of two or more.

If the amount is less than each lower limit, the number or amount of each compound particle formed in the crystal grain is insufficient, and there is no effect of miniaturizing the recrystallized grain size during recrystallization annealing to 5 μm or less.
On the other hand, if the respective upper limits are exceeded, the crystal grain refining effect is saturated, and a coarse crystallized substance is generated.
Deterioration of fracture toughness and fatigue properties, elongation, formability, etc. of Al alloy sheets. Therefore, each content,
Cr: 0.05 to 0.2%, Zr: 0.05 to 0.2%.

Ti: 0.001 to 0.1%, B: 1 to 300 ppm. Ti and B have the effect of refining the crystal grains of the ingot. For this reason, Ti is an element usually added. If the content of Ti is less than 0.001% and the content of B is less than 1 ppm, this effect cannot be obtained. On the other hand, if the content of Ti exceeds 0.1% and the content of B exceeds 300 ppm, coarse crystals are formed. Therefore, when one or two types of Ti and B are contained, the content of Ti is 0.001 to 0.
The content of B is preferably in the range of 1 to 300 ppm, and the content of B is preferably in the range of 1 to 300 ppm.

(Method of Manufacturing Al Alloy Sheet of the Present Invention) Although the Al alloy sheet itself can be manufactured by an ordinary method, the Al-Mn system in the crystal grains of the Al alloy sheet at the time of final annealing and after the final annealing is performed. Preferred process conditions for setting the maximum length of the compound to 500 nm or less and for setting the recrystallized grain size after final annealing to 5 μm or less are described below.

In the casting step in which the solid solution and precipitation of the Al-Mn compound particles are initially controlled, it is preferable to promote the solid solution and suppress the precipitation. For this purpose, it is preferable that the cooling rate during casting be high. In this regard, rather than a semi-continuous casting method having a fixed water-cooled mold (DC casting method), a twin-roll method having a rotary water-cooled mold, a belt caster method,
In continuous casting such as the 3C method and the block method, the cooling rate during solidification (from the liquidus temperature to the solidus temperature) can be 2 ° C / sec to 10 ° C / sec.

In the homogenizing heat treatment of these Al alloy ingots before hot rolling, in order to precipitate a large number of Al-Mn-based compound particles, the homogenizing heat treatment temperature should be about 430 to 520 ° C. preferable. At processing temperatures above 520 ° C,
Al-Mn-based compound particles are likely to become coarse. If the temperature of the heat treatment for homogenization is lower than 430 ° C., the effect of the homogenization itself by solid solution is insufficient.

Although hot rolling can be performed by a conventional method, the working ratio of hot rolling also affects the rolling reduction of cold rolling described below. In order to increase the working ratio (reduction ratio) of cold rolling described later, when the final plate thickness is the same, it is preferable that the plate thickness at the end of hot rolling be large. Further, it is preferable to increase the strain (dislocation density) introduced during hot rolling, and therefore, it is preferable that the hot rolling end temperature is lower.

The rolling reduction in the subsequent cold rolling is important to keep the recrystallized grain size after final annealing to 5 μm or less. The recrystallization grain size of a normal cold-rolled Al-Mg-based Al alloy sheet is
The level of 3030 μm is attributable to the relatively low Mg content and the level of the cold rolling reduction of less than 90% at most. Therefore, in the present invention, it is necessary to perform cold rolling at a rolling reduction of 90% or more, and at a rolling reduction of less than this, the recrystallized grain size after final annealing cannot be reduced to 5 μm or less. By cold rolling at a rolling reduction of 90% or more, dislocations are introduced at a high density, local deformation regions are formed at a high density, and these act as nucleation sites for recrystallization. The crystal grain size can be reduced to 5 μm or less.

The intermediate annealing during the cold rolling and the final annealing (recrystallization annealing) after the cold rolling are carried out by a batch type heat treatment furnace or a continuous type heat treatment furnace by using the mechanical properties and formability required for the product sheet. It is performed by temperature and time according to the required characteristics such as.

In order to make the recrystallized grain size ultra-fine with good reproducibility even by high-temperature annealing, it is necessary to simply make the Al-Mn-based compound fine with good reproducibility before final annealing at high temperature. It is important to control the size of the Al-Mn-based compound in consideration of not only the chemical composition and the ordinary basic manufacturing process, but also the cooling rate and the homogenizing heat treatment conditions in casting the ingot. In other words, even if the other conditions are the same, the size of the Al-Mn-based compound will be significantly different if the cooling rate and the homogenizing heat treatment conditions in casting are different.

[0041]

Next, an embodiment of the method of the present invention will be described. table 1
Al-Mg system with chemical composition of No.A to J shown in
Using an Al alloy and changing various manufacturing conditions as shown in Table 2.
The test material of the Al alloy plate was manufactured.

Incidentally, in Table 1, A to C are compositions within the scope of the present invention, and are examples of the invention in which the amount of Mn is changed. D to G are compositions within the scope of the present invention, and are examples of the invention to which one or more of Fe, Cr, and Zr are added, D is an invention example in which the amount of Mg is the upper limit, and E is
It is an invention example in which the amount of Mg is relatively small. Further, H to J are compositions outside the range of the present invention, H is a comparative example not containing a refining element such as Mn, I is a comparative example in which Mn is less than the lower limit and Fe, Cr, and Zr are added. J is a comparative example in which the amount of Mg is less than the lower limit.

A specific method of manufacturing an Al alloy plate is an Al-Mg-based
50mm of Al alloy ingot by DC casting method (cooling rate 5 ℃ / sec)
After being melted into thick ingots, they were subjected to a homogenizing heat treatment (at a common heating rate of 50 ° C / sec) for 4 hours at each temperature shown in Table 2. Then, hot rolling was started from this heat treatment temperature,
The rolling was completed at 0 ° C. and hot-rolled to a thickness of 10 mm. Furthermore, these hot-rolled sheets can be reduced to a thickness of 0.4 to
Cold rolling was performed at a reduction ratio shown in Table 2 from a large reduction ratio of 85% to a reduction ratio of 85%. Then, the cold-rolled sheet was subjected to final annealing (recrystallization annealing) at a temperature shown in Table 2 for 20 seconds (heating rate was 100 ° C./second in common) using a salt bath.

In Table 2, Nos. 1 to 3 correspond to A in Table 1.
Using an Al alloy plate having a composition within the scope of the present invention,
This is an example of the invention in which the temperature is changed from 0 to 500 ° C. No. 4 is an invention example in which an Al alloy sheet having a composition within the range of the present invention of A was used and the cold rolling reduction was 90% of the lower limit of the present invention. No. 5 is an invention example in which an Al alloy plate having a composition within the range of the present invention of A is used and the temperature of the homogenization heat treatment is relatively low at 470 ° C. No. 6 to 11 are shown in Table 1.
Using an Al alloy plate having a composition within the range of the present invention from B to G,
This is an invention example in which the manufacturing conditions are exactly the same.

Further, in Table 2, Nos. 12 to 14 correspond to H in Table 1.
This is a comparative example in which Al alloy plates having compositions out of the range of the present invention from No. 1 to No. J were used, and the production conditions were exactly the same as those of Invention Example No. 1. No. 15 is a comparative example in which an Al alloy plate having a composition within the range of the present invention A in Table 1 was used and the cold rolling reduction was 85%, which is less than the lower limit of the present invention. No. 16 is a comparative example in which the temperature of the homogenizing heat treatment was relatively high at 540 ° C.

(Measurement of Al-Mn-based compound particles) Identification and maximum length of Al-Mn-based compound particles in recrystallized grains of Al alloy plate of each example, and size of recrystallized grains (recrystallized grain size) Was measured by the measurement method described above. Table 2 shows the results.

(Evaluation of characteristics of Al alloy plate) Further, a tensile test (JIS
Z 2241 method) to conduct a tensile test, and the tensile strength (σ _B )
The proof stress (σ _0.2 ) and elongation (%) were measured. These results are tabulated.
See Figure 2.

Further, in order to evaluate the press formability of each of the test plates, a blank was sampled from the test plates, and LDH _O
Using a mold for measurement (ball-head punch with a diameter of 50.8 mmφ),
Perform simple spherical head overhanging test was determined was molded LDH _O (fully extended height) without causing cracks at that time. Table 2 also shows these results.

As is clear from Table 2, Invention Examples Nos. 1 to 11
Means that even if the final annealing reaches a high temperature of 500
The maximum length of the Al-Mn-based compound particles in the recrystallized grains of the Al alloy plate is 500 nm or less, and the recrystallized grains are ultra-fine grains of 5 μm or less. As a result, as shown in Table 2, it shows a high forming limit height as well as excellent tensile strength (σ _B ), proof stress (σ _0.2 ) and elongation (%). In addition, Invention Example No. 11
Even when the final annealing is at a low temperature of 320 ° C, the recrystallized
This indicates that the particles become ultra-fine particles of μm or less. Therefore, the results also show that the Al alloy sheet of the present invention has an advantage that the final annealing temperature can be appropriately selected from a low temperature to a high temperature according to required characteristics.

The results of Invention Example No. 3 are described in Japanese Patent Application No.
The example of -268599 (the recrystallization grain size exceeds 5 μm when the final annealing temperature of the Al-Mg-based Al alloy sheet containing Mn is high) becomes larger.

On the other hand, in Table 2, the present invention from H to J in Table 1
Manufacturing conditions using Invention alloy N
Comparative Examples Nos. 12 and 13 which were completely the same as o.1 were Al-Mn based
No or small amount of compound particles per se, Comparative Example No. 1
No. 4 has a small amount of Mg, so all of them have a nucleation site for recrystallization.
Shortage, recrystallization during high temperature recrystallization annealing at 350 ° C or higher
It cannot be made into ultra-fine particles with a particle size of 5 μm or less. Ma
Further, using an Al alloy plate having a composition within the range of the present invention A in Table 1,
Comparative Example N where the cold rolling reduction was 85%, which is less than the lower limit of the present invention.
o.15 lacks nucleation sites for recrystallization,
Ultra fine particles with a recrystallized grain size of 5 μm or less during high temperature recrystallization annealing
Cannot be fine. Further, the present invention of A of Table 1
Using an Al alloy plate with the composition in the box, set the homogenization heat treatment temperature to 540.
Comparative Example No. 16 in which the temperature was as high as
High temperature recrystallization at 350 ° C or more with a maximum length exceeding 500nm
Ultra-fine grains with a recrystallized grain size of 5 μm or less during dulling
Can not. As a result, each of these comparative examples
As shown in Table 2, the tensile strength (σ _B), Proof stress (σ_0.2),
Elongation (%) and molding limit height are significantly inferior to the invention examples
ing.

Therefore, these results reveal the critical significance of the requirements of the present invention and the significance of the preferred production conditions. Further, the maximum length and the recrystallized grain size of the Al-Mn-based compound particles greatly differ depending on the recrystallization annealing temperature, the alloy composition, and the manufacturing conditions. Only by defining the maximum length of the Al-Mn-based compound particles of the present invention, It can be seen that a recrystallization grain size of 5 μm or less during recrystallization annealing at a high temperature of 350 ° C. or more is guaranteed.

[0053]

[Table 1]

[0054]

[Table 2]

[0055]

According to the present invention, there is provided an Al-Mg-based Al alloy sheet capable of forming ultra-fine grains having a recrystallized grain size of 5 μm or less even after high-temperature recrystallization annealing. can do. As a result, the industrial value is great in that the applications of the Al alloy material for transport aircraft can be greatly expanded.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C22F 1/00 630 C22F 1/00 630K 685 685 694 694A 694B (71) Applicant 000004743 Nippon Light Metal Co., Ltd. Tokyo Furukawa Electric Co., Ltd. 2-6-1 Marunouchi, Chiyoda-ku, Tokyo (71) Applicant 000176707 Mitsubishi Aluminum Co., Ltd. 2-3-3 Shiba, Minato-ku, Tokyo No.3 (72) Inventor Kazunori Kobayashi 1-5-5 Takatsukadai, Nishi-ku, Kobe-shi Kobe Steel, Ltd.Kobe Research Institute

Claims (4)

[Claims] (1) Mg: 3.0 to 10.0% (% by mass, the same applies hereinafter),
Mn: 0.1 to 1.5%, the balance being Al and unavoidable impurities.In the cold rolling, a reduction of 90% or more is applied, and the recrystallized grain size after final annealing is 5 μm or less.
-Mg-based aluminum alloy sheet, characterized in that the maximum length of the Al-Mn-based compound dispersed and precipitated in the structure is 500 nm or less, and high strength with excellent recrystallization grain refinement during high temperature annealing Formable aluminum alloy plate. 2. The method according to claim 1, wherein the aluminum alloy plate further comprises Fe:
The high-strength high-formability aluminum having excellent refining grain refining during high-temperature annealing according to claim 1, comprising one or more of 0.1 to 2.0%, Cr: 0.05 to 0.2%, and Zr: 0.05 to 0.2%. Alloy plate. 3. The method according to claim 2, wherein the aluminum alloy plate further comprises Ti:
The high-strength high-formability aluminum alloy sheet according to claim 1 or 2, which contains one or two kinds of 0.001 to 0.1% and B: 1 to 300 ppm. 4. The method according to claim 1, wherein the annealing temperature exceeds 350 ° C.
4. A high-strength, high-formability aluminum alloy sheet excellent in refining recrystallized grains during high-temperature annealing according to any one of 3 to 3 above.