U.S. patent application number 17/429823 was filed with the patent office on 2022-04-28 for aluminum alloy material.
The applicant listed for this patent is GLOLINX CO., LTD., UACJ CORPORATION. Invention is credited to Jin-Gyo Kim, Tomohito Kurosaki, Tadashi Minoda, Mitsuhiro Tamaki.
Application Number | 20220127702 17/429823 |
Document ID | / |
Family ID | |
Filed Date | 2022-04-28 |
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United States Patent
Application |
20220127702 |
Kind Code |
A1 |
Kurosaki; Tomohito ; et
al. |
April 28, 2022 |
ALUMINUM ALLOY MATERIAL
Abstract
An aluminum alloy material contains Mg: 7.0% to 10.0% (% by
mass, the same applies hereinafter) and Ca: not more than 0.1%, and
the aluminum alloy material contains a remainder constituted by
aluminum and an inevitable impurity. The aluminum alloy material
has a tensile strength of not less than 300 MPa and less than 500
MPa and an elongation of not less than 20%.
Inventors: |
Kurosaki; Tomohito; (Tokyo,
JP) ; Minoda; Tadashi; (Tokyo, JP) ; Tamaki;
Mitsuhiro; (Tokyo, JP) ; Kim; Jin-Gyo;
(Suwon-si, KR) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
UACJ CORPORATION
GLOLINX CO., LTD. |
Tokyo
Suwon-si, Gyeonggi-do |
|
JP
KR |
|
|
Appl. No.: |
17/429823 |
Filed: |
October 8, 2020 |
PCT Filed: |
October 8, 2020 |
PCT NO: |
PCT/JP2020/038087 |
371 Date: |
August 10, 2021 |
International
Class: |
C22C 21/06 20060101
C22C021/06; C22F 1/047 20060101 C22F001/047 |
Foreign Application Data
Date |
Code |
Application Number |
Oct 8, 2019 |
JP |
2019-185299 |
Claims
1. An aluminum alloy material containing Mg: 7.0% to 10.0% (% by
mass, the same applies hereinafter) and Ca: not more than 0.1%, the
aluminum alloy material containing a remainder being constituted by
aluminum and an inevitable impurity, the aluminum alloy material
having a tensile strength of not less than 300 MPa and less than
500 MPa and an elongation of not less than 20%.
2. The aluminum alloy material according to claim 1, wherein the
aluminum alloy material contains Mn: 0.05% to 1.0%.
3. The aluminum alloy material according to claim 1, wherein the
aluminum alloy material has a standard deviation of tensile
strengths of not more than 10, in a plane defined by a final
working direction and a transverse direction of the aluminum alloy
material, wherein the tensile strengths are a tensile strength in a
0.degree. direction, which is the final working direction, a
tensile strength in a 45.degree. direction forming an angle of
45.degree. with the 0.degree. direction from the final working
direction toward the transverse direction, and a tensile strength
in a 90.degree. direction forming an angle of 90.degree. with the
0.degree. direction from the final working direction toward the
transverse direction.
4. The aluminum alloy material according to claim 3, wherein the
aluminum alloy material has a {013}<100> orientation density
of not more than 5 and a {011}<100> orientation density of
not more than 5, wherein the {013}<100> orientation density
and the {011}<100> orientation density are calculated using a
crystallite orientation distribution function (ODF).
5. The aluminum alloy material according to claim 3, wherein the
aluminum alloy material has a {123}<634> orientation density
of not more than 5 and a {001}<100> orientation density of
not more than 5, wherein the {123}<634> orientation density
and the {001}<100> orientation density are calculated using a
crystallite orientation distribution function (ODF).
6. The aluminum alloy material according to claim 2, wherein the
aluminum alloy material has a standard deviation of tensile
strengths of not more than 10, in a plane defined by a final
working direction and a transverse direction of the aluminum alloy
material, wherein the tensile strengths are a tensile strength in a
0.degree. direction, which is the final working direction, a
tensile strength in a 45.degree. direction forming an angle of
45.degree. with the 0.degree. direction from the final working
direction toward the transverse direction, and a tensile strength
in a 90.degree. direction forming an angle of 90.degree. with the
0.degree. direction from the final working direction toward the
transverse direction.
7. The aluminum alloy material according to claim 6, wherein the
aluminum alloy material has a {013}<100> orientation density
of not more than 5 and a {011}<100> orientation density of
not more than 5, wherein the {013}<100> orientation density
and the {011}<100> orientation density are calculated using a
crystallite orientation distribution function (ODF).
8. The aluminum alloy material according to claim 4, wherein the
aluminum alloy material has a {123}<634> orientation density
of not more than 5 and a {001}<100> orientation density of
not more than 5, wherein the {123}<634> orientation density
and the {001}<100> orientation density are calculated using a
crystallite orientation distribution function (ODF).
9. The aluminum alloy material according to claim 6, wherein the
aluminum alloy material has a {123}<634> orientation density
of not more than 5 and a {001}<100> orientation density of
not more than 5, wherein the {123}<634> orientation density
and the {001}<100> orientation density are calculated using a
crystallite orientation distribution function (ODF).
10. The aluminum alloy material according to claim 7, wherein the
aluminum alloy material has a {123}<634> orientation density
of not more than 5 and a {001}<100> orientation density of
not more than 5, wherein the {123}<634> orientation density
and the {001}<100> orientation density are calculated using a
crystallite orientation distribution function (ODF).
Description
TECHNICAL FIELD
[0001] The present invention relates to a high-strength aluminum
alloy material having reduced strength anisotropy.
BACKGROUND ART
[0002] Recently, there has been a demand for using an aluminum
alloy material to make stronger and lighter various products
including, for example, a housing of an electrical device. Using an
aluminum alloy material having higher strength makes it possible to
reduce the amount of usage of the aluminum alloy material while
maintaining the strength of the products at the same degree as
before, and thus enables reduction in the weights of the
products.
[0003] Typical high-strength aluminum alloys include, for example,
a 6000 series alloy and a 7000 series alloy. However, the
above-described alloys are heat-treatable alloys, which require
solution treatment and aging heat treatment, and thus have a
problem of low production efficiency. In addition, the 7000 series
alloy contains Zn and Cu in a large amount, and thus have a problem
of causing corrosion to easily occur depending on usage
environments.
[0004] In view of the above, non-heat-treatable aluminum alloys are
used in some cases. Typical non-heat-treatable aluminum alloys
include a 5000 series alloy, which has the highest strength. The
5000 series alloy, which typically has excellent corrosion
resistance, does not require the solution treatment and the aging
heat treatment, so that the 5000 series alloy is produced with high
efficiency. Further, increase in the amount of an element added to
the 5000 series alloy makes it possible to achieve the 5000 series
alloy having strength not less than that of a 6000 series alloy.
For the above reasons, proposed is a 5000 series aluminum alloy
material containing not less than 5% by weight of Mg, which is a
major additive element (see Patent Literatures 1 to 3).
CITATION LIST
Patent Literature
[Patent Literature 1]
[0005] Japanese Patent Application Publication, Tokukai, No.
2007-186747
[Patent Literature 2]
[0006] Japanese Patent Application Publication, Tokukai, No.
2001-98338
[Patent Literature 3]
[0007] Japanese Patent Application Publication, Tokukaihei, No.
7-197170
SUMMARY OF INVENTION
Technical Problem
[0008] The contents of Mg in the aluminum alloy materials described
in the above Patent Literatures 1 to 3 are increased to an amount
of not less than 5% by weight to make the aluminum alloy material
stronger. However, Patent Literatures 1 to 3 do not give any
consideration to strength anisotropy of the aluminum alloy
materials.
[0009] In a case where an aluminum alloy material has high strength
anisotropy, an end product has low rigidity in a particular
direction, so that the reliability of the end product could
decrease. In addition, failure in dimension accuracy or other
accuracy could occur in a production process such as press forming.
In particular, an aluminum alloy material (O tempered material)
which has been annealed is required to have high formability, and
therefore, the O tempered material having high strength anisotropy
could lead to the occurrence of cracking in a press forming
process.
[0010] It is an object of an aspect of the present invention, which
has been made to solve the above problem, to provide an aluminum
alloy material which has both high strength and reduced strength
anisotropy, by controlling the metal structure.
Solution to Problem
[0011] To solve the above problems, an aluminum alloy material in
accordance with an aspect of the present invention contains Mg:
7.0% to 10.0% (% by mass, the same applies hereinafter) and Ca: not
more than 0.1%, the aluminum alloy material containing a remainder
constituted by aluminum and an inevitable impurity, the aluminum
alloy material having a tensile strength of not less than 300 MPa
and less than 500 MPa and an elongation of not less than 20%.
Advantageous Effects of Invention
[0012] An aspect of the present invention makes it possible to
produce an aluminum alloy material which has both high strength and
reduced strength anisotropy.
BRIEF DESCRIPTION OF DRAWINGS
[0013] FIG. 1 is a view illustrating measurement directions of
tensile strengths of an aluminum alloy material in the present
embodiment.
DESCRIPTION OF EMBODIMENTS
[0014] The inventors of the present invention diligently
investigated and studied alloy composition and metal structure
which enable reduction in the strength anisotropy of a
high-strength aluminum alloy material containing Mg (magnesium) in
a large amount. The inventors eventually found that it is possible
to reduce the strength anisotropy by controlling an appropriate
metal structure through adjustments to the alloy composition and to
a production process.
[0015] The following description will discuss an aluminum alloy
material in accordance with an embodiment of the present invention
in detail. Note that it is assumed that the aluminum alloy material
of the present embodiment is used for members of household
electrical appliances, buildings, structures, transport equipment,
and the like that are required to have strength and isotropy of
strength. In the following description, the unit "% by mass" is
abbreviated and written simply as "%".
[0016] (Elements Which Must Be Contained in Aluminum Alloy)
[0017] [Mg]
[0018] Mg (magnesium) is present mainly in the form of a solid
solution element, and has an effect of improving strength. The
content of Mg in the aluminum alloy being not less than 7.0% makes
it possible to sufficiently obtain the effect of improving
strength.
[0019] However, the content of Mg in the aluminum alloy exceeding
10.0% causes occurrence of cracking during hot rolling, and thus
could lead to difficulty in production. Accordingly, the content of
Mg in the aluminum alloy is preferably in a range of not less than
7.5% and not more than 9.0%, and more preferably in a range of not
less than 7.5% and not more than 8.5%.
[0020] [Ca]
[0021] Ca (Calcium) is present in the aluminum alloy mainly in the
form of a compound. Even trace amounts of Ca cause cracking during
hot working, and thus could lower workability. The content of Ca in
the aluminum alloy being not more than 0.1% makes it possible to
prevent cracking during hot working. The content of Ca in the
aluminum alloy is more preferably not more than 0.05%.
[0022] (Elements Selectively Contained in Aluminum Alloy)
[0023] [Si]
[0024] Si (silicon) forms mainly second phase particles (for
example, single Si, Al--Si--Fe--Mn-based compound), and has an
effect of making crystal grains finer by acting as a nucleation
site for recrystallization. The content of Si in the aluminum alloy
being not less than 0.02% makes it possible to successfully obtain
the effect of making crystal grains finer.
[0025] However, the content of Si in the aluminum alloy exceeding
0.3% cause generation of a large amount of coarse second phase
particles, and thus could lower the elongation of a produced
aluminum alloy material. Accordingly, the content of Si in the
aluminum alloy is preferably in a range of not less than 0.02% and
not more than 0.2%, and more preferably in a range of not less than
0.02% and not more than 0.15%.
[0026] [Fe]
[0027] Fe (iron) is present mainly in the form of second phase
particles (such as an Al--Fe-based compound), has an effect of
making crystal grains finer by acting as a nucleation site for
recrystallization. The content of Fe in the aluminum alloy being
not less than 0.02% makes it possible to obtain the effect of
making crystal grains finer.
[0028] However, the content of Fe in the aluminum alloy exceeding
0.5% causes generation of a large amount of coarse second phase
particles, and thus could lower the elongation of a produced
aluminum alloy material. Accordingly, the content of Fe in the
aluminum alloy is preferably in a range of not less than 0.02% and
not more than 0.25%, and more preferably in a range of not less
than 0.02% and not more than 0.2%.
[0029] [Cu]
[0030] Cu (copper) is present mainly in the form of a solid
solution element, and has an effect of improving strength. The
content of Cu in the aluminum alloy being not less than 0.05% makes
it possible to sufficiently obtain the effect of improving
strength.
[0031] However, the content of Cu in the aluminum alloy exceeding
1.0% causes occurrence of cracking during hot rolling, and thus
could lead to difficulty in production. Accordingly, the content of
Cu in the aluminum alloy is preferably in a range of not less than
0.05% and not more than 0.5%, and more preferably in a range of not
less than 0.10% and not more than 0.3%.
[0032] [Mn]
[0033] Mn (manganese) is present mainly in the form of second phase
particles (an Al--Mn-based compound), and has an effect of making
crystal grains finer by acting as a nucleation site for
recrystallization. Specifically, the content of Mn in the aluminum
alloy being not less than 0.05% makes it possible to sufficiently
obtain the effect of making crystal grains finer.
[0034] However, the content of Mn in the aluminum alloy exceeding
1.0% causes generation of a large amount of coarse second phase
particles, and thus lower the elongation of a produced aluminum
alloy material. Accordingly, the content of Mn in the aluminum
alloy is preferably in a range of not less than 0.1% and not more
than 0.5%, and more preferably in a range of not less than 0.15%
and not more than 0.3%.
[0035] [Cr, V, Zr]
[0036] Cr (chromium), V (vanadium), and Zr (zirconium) are present
mainly in the form of second phase particles (such as an
Al--Fe--Mn-based compound, an Al--Cr-based compound, an Al--V-based
compound, and an Al--Zr-based compound), and have an effect of
making crystal grains finer by acting as a nucleation site for
recrystallization. Specifically, the content of Cr or V in the
aluminum alloy being not less than 0.05% or the content of Zr in
the aluminum alloy being not less than 0.02% makes it possible to
sufficiently obtain the effect of making crystal grains finer.
[0037] However, the content of Cr or V in the aluminum alloy
exceeding 0.3%, or the content of Zr exceeding 0.2% causes
generation of a large amount of coarse second phase particles, and
thus could lower the elongation of a produced aluminum alloy
material.
[0038] Accordingly, the content of Cr or V in the aluminum alloy is
preferably not more than 0.2%. In addition, the content of Zr in
the aluminum alloy is preferably 0.1%.
[0039] The contents of Cr, V, and Zr in the aluminum alloy are not
limited to the above respective contents, provided that at least
one of Cr, V, and Zr is contained in the aluminum alloy.
[0040] [Ti]
[0041] Ti (titanium) inhibits the growth of a solidified phase of
aluminum formed during casting and makes a cast structure finer,
thus having an effect of preventing a defect such as cracking
during casting. However, an excessively high content of Ti in the
aluminum alloy makes second phase particles coarse, and thus could
decrease the elongation of a produced aluminum alloy material.
[0042] In light of the above, the content of Ti in the aluminum
alloy being not more than 0.2% makes it possible to prevent a
decrease in the elongation of the produced aluminum alloy material.
The content of Ti in the aluminum alloy is more preferably not more
than 0.1%. Note that substances other than the elements described
above are basically Al and an inevitable impurity.
[0043] (Tensile Strength and Elongation)
[0044] The present embodiment enables production of an aluminum
alloy material (H tempered material) having a tensile strength of
not less than 300 MPa and less than 500 MPa and an elongation of
not less than 20%, by performing production treatments (which will
be discussed later) on the aluminum alloy of the above composition.
This makes it possible to prevent an end product from having poor
strength due to the aluminum alloy having a tensile strength
falling below 300 MPa. It is also possible to prevent the
occurrence of a defect such as cracking during working on the end
product due to the aluminum alloy having an elongation falling
below 20%.
[0045] The tensile strength of the aluminum alloy material is more
preferably not less than 350 MPa. Further, the elongation of the
aluminum alloy material is more preferably not less than 25%.
[0046] (Strength Anisotropy)
[0047] As illustrated in FIG. 1, an aluminum alloy material 1 of
the present embodiment is set such that, in a plane defined by a
rolling direction (a final working direction) during a final
rolling using a set of rolls 2 and a transverse direction, a
standard deviation of tensile strengths is not more than 10 [MPa],
wherein the tensile strengths are: a tensile strength in a
0.degree. direction forming an angle of 0.degree. with the rolling
direction toward the transverse direction, a tensile strength in a
45.degree. direction forming an angle of 45.degree. with the
rolling direction toward the transverse direction, and a tensile
strength in a 90.degree. direction forming an angle of 90.degree.
with the rolling direction towards the transverse direction. This
setting is made in consideration of the fact that the standard
deviation of the tensile strengths exceeding 10 [MPa], which means
an excessively high strength anisotropy, decreases the strength in
a particular direction of an end product and could decrease the
reliability of the end product. The standard deviation of the
tensile strengths is calculated by using Formula (1) (which will be
described later).
[0048] The standard deviation of the tensile strengths of the
aluminum alloy material 1 is preferably not more than 5 [MPa], and
more preferably not more than 3 [MPa].
[0049] (Crystallographic Texture)
[0050] The aluminum alloy material of the present embodiment is set
to have a {013}<100> orientation density and a
{011}<100> orientation density which are calculated using a
Crystallite Orientation Distribution Function (ODF) and which are
each not more than 5 (for example, approximately 1). This setting
is made in consideration of the fact that the {013}<100>
orientation density and the {011}<100> orientation density
both exceeding 5 makes the strength anisotropy remarkable and thus
could decrease the strength of an end product in a particular
direction.
[0051] In addition, the aluminum alloy material of the present
embodiment is set to have a {123}<634> orientation density of
not more than 5 and a {001}<100> orientation density of not
more than 5. Such a setting is made in consideration of the fact
that the {123}<634> orientation density and the
{001}<100> orientation density both exceeding 5 could make
the strength anisotropy remarkable.
[0052] Now, a method for calculating an orientation density using
the crystallite orientation distribution function (ODF) will be
described in detail. In the present embodiment, a three-dimensional
orientation analyzing method (see, Journal of Japan Institute of
Light Metals, 1992, volume 42, No. 6, pp. 358 to 367) using the
crystallite orientation distribution function (ODF) is applied to a
produced aluminum alloy material to calculate an orientation
density. First, a cross section of the aluminum alloy material
perpendicular to the working direction (rolling direction) is
measured by an X-ray diffractometry. In this measurement,
incomplete pole figures of (111), (220), and (200) planes are
measured in an inclination angle range of 15 degrees to 90 degrees,
using the Schlz reflection method (see, Journal of Japan Institute
of Light Metals, 1983, volume 33, No. 4, pp. 230 to 239). Next, the
crystallite orientation distribution function (ODF) is determined
through a series expansion. From this, an orientation density of
each orientation is calculated as a ratio with respect to the
orientation density of a standard sample having random
crystallographic texture.
[0053] (Method for Producing Aluminum Alloy Material)
[0054] The following description will discuss a method for
producing the aluminum alloy material in accordance with the
present embodiment. The method for producing the aluminum alloy
material of the present embodiment is carried out in the order of a
casting step, a homogenization step, a hot rolling step, a cold
rolling step, and an anneal step. Steps of the production method
are not limited to these steps, which are illustrated by way of
example.
[0055] First, a slab is casted in the casting step by a
semi-continuous casting process such as a Direct Chill (DC) casting
process and a hot top process. The casting speed in the casting
step is preferably 20 mm/min to 100 mm/min to prevent formation of
coarse second phase particles.
[0056] Upon completion of the casting step, the homogenization step
is carried out. The treatment temperature is set to not less than
400.degree. C. and not more than 490.degree. C. This is because (i)
the treatment temperature being not more than 400.degree. C. could
cause insufficient homogenization, and (ii) the treatment
temperature exceeding 490.degree. C. could cause melting of an
Al--Mg-based compound remaining without dissolving as a solid
solution, and thus cause a defect such as cracking during the hot
rolling. Further, coarsening of second phase particles excessively
progresses, and crystal grains in a particular orientation tend to
preferentially grow in the subsequent recrystallization process, so
that the strength anisotropy could decrease.
[0057] In the homogenization step of the present embodiment, a
two-stage homogenization treatment may be carried out. In that
case, the treatment temperature for the first stage is set to not
less than 400.degree. C. and not more than 450.degree. C. This is
because (i) the treatment temperature for the first stage being not
more than 400.degree. C. could cause insufficient homogenization,
and (ii) the treatment temperature for the first stage exceeding
450.degree. C. could cause melting of an Al--Mg-based compound
remaining without dissolving as a solid solution, and thus cause a
defect such as cracking during the hot rolling.
[0058] Further, the treatment time for the first stage is set to be
in a range of not less than five hours and not more than 20 hours.
This is because (i) the treatment time for the first stage being
less than five hours causes insufficient homogenization, and (ii)
the treatment time for the first stage exceeding 20 hours causes
decrease in productivity. Carrying out the homogenization treatment
in the first stage with the treatment temperature and the treatment
time being appropriately set as described above makes it possible
to cause the Al--Mg-based compound to dissolve as a solid solution,
and thus enables homogenization at a higher temperature.
[0059] Subsequently, the treatment temperature for the second stage
is set to not less than 450.degree. C. and not more than
490.degree. C. This is because (i) the treatment temperature for
the second stage being less than 450.degree. C. causes insufficient
homogenization, and (ii) the treatment temperature for the second
stage exceeding 490.degree. C. causes oxidization of Mg on the
surface to progress and thus could decrease concentration of Mg on
the surface.
[0060] Further, the treatment time for the second stage is set to
be in a range of not less than five hours and not more than 20
hours. This is because (i) the treatment time for the second stage
being less than five hours causes insufficient homogenization, and
(ii) the treatment time for the second stage exceeding 20 hours
causes coarsening of second phase particles to excessively
progress, causes crystal grains in a particular orientation to tend
to preferentially grow in the subsequent recrystallization process,
and thus could decrease the strength anisotropy.
[0061] Next, the hot rolling step is carried out. In the hot
rolling step, the starting temperature for the hot rolling is set
to be in a range of not less than 350.degree. C. and not more than
480.degree. C. This is because (i) the treatment temperature for
the hot rolling being less than 350.degree. C. could make the
rolling difficult due to excessively high deformation resistance,
and (ii) the treatment temperature for the hot rolling exceeding
480.degree. C. causes the material to partially melt, and thus
could lead to the occurrence of cracking. Note that the hot rolling
step may be carried out with the homogenization step omitted.
[0062] Subsequently, upon completion of the hot rolling step, the
cold rolling step is carried out. In the cold rolling step, the
cold rolling is carried out such that a rolling reduction from the
plate thickness at the time of completion of the hot rolling step
to the plate thickness at the time of completion of the cold
rolling step (a ratio of a plate thickness after working to a plate
thickness before the working) is not less than 50%. The rolling
reduction only needs to be not less than 50%, and may be changed as
appropriate.
[0063] Note that an intermediate annealing may be carried out
before or in the middle of the cold rolling step. In this case, the
cold rolling is also carried out such that the rolling reduction
from the plate thickness at the time of completion of the
intermediate annealing to the plate thickness at the time of
completion of the cold rolling is not less than 50%. A treatment
temperature for the intermediate annealing is preferably in a range
of not less than 300.degree. C. and not more than 400.degree. C.
Further, a retention time for the intermediate annealing is
preferably in a range of not less than one hour and not more than
10 hours. This is because carrying out the intermediate annealing
at a high temperature for a long time could cause deterioration in
appearance quality due to progression of oxidization on the
surface.
[0064] Further, after completion of the cold working step, a final
annealing step is carried out. In the annealing step, an annealing
temperature is preferably not less than 300.degree. C. and not more
than 400.degree. C., and a retention time is preferably not less
than one hour and not more than five hours. The treatment
temperature falling below 300.degree. C. could cause insufficient
annealing effect. The treatment temperature exceeding 400.degree.
C. causes oxidization on the surface to progress and thus could
cause deterioration in appearance quality.
[0065] According to the aluminum alloy material of the present
embodiment described above, it is possible to produce an aluminum
alloy material having both high strength and reduced strength
anisotropy by appropriately controlling the metal structure through
adjustments to the composition of the aluminum alloy and the
production process for the aluminum alloy. This enables improvement
in productivity of the aluminum alloy material and improvement in
reliability of an end product.
EXAMPLES
[0066] The following description will discuss Example 1 of the
present embodiment with reference to Table 1 and Table 2.
[0067] (Composition of Aluminum Alloy)
[0068] Table 1 shows the composition of the aluminum alloy used in
Example 1.
TABLE-US-00001 TABLE 1 Present Composition of Aluminum Alloy [% by
Mass] Invention Fe Si Cu Mn Mg Cr Ti V Zr Ca Al Example 1 0.22 0.10
<0.01 0.40 7.6 0.02 0.03 0.01 <0.01 <0.01 Remaining
Percentage
[0069] As shown in Table 1, the composition of the aluminum alloy
of Example 1 is within a predetermined range. The predetermined
range means that the content of Mg is in a range of 7.0% to 10.0%,
and the content of Ca is in a range of not more than 0.1%.
[0070] (Production Method)
[0071] After the aluminum alloy having the composition shown in
Table 1 is molten and is subjected to the DC casting, the
homogenization step, the hot rolling step, the cold rolling step,
and the final annealing step are carried out. The plate thickness
of the aluminum alloy material after completion of the cold rolling
step is assumed to be 1.0 mm.
[0072] In Example 1, heating at 465.degree. C. for 12 hours is
carried out in the homogenization step prior to the hot rolling
step. In the cold rolling step, the rolling reduction from the
plate thickness at the time of completion of the hot rolling to the
plate thickness at the time of completion of the cold rolling is
assumed to be 80%. In the final annealing step, heating at
360.degree. C. for two hours is carried out.
[0073] (Property of Aluminum Alloy Material)
[0074] Table 2 shows the strength property, the strength
anisotropy, and the productivity of an aluminum alloy material
produced by performing the above treatment on the aluminum alloy of
Example 1 having the composition shown in Table 1.
TABLE-US-00002 TABLE 2 Tensile Strength {001}<100>
{011}<100> {123}<634> {001}<100> Present Strength
Elongation Anisotropy Orientation Orientation Orientation
Orientation Invention [MPa] [%] [MPa] Density Density Density
Density Productivity Example 1 364 32 1 G G G G G
[0075] (Tensile Strength and Elongation)
[0076] As shown in Table 2, the aluminum alloy material produced in
Example 1 has a tensile strength and an elongation within the
respective predetermined ranges. In other words, the aluminum alloy
material produced in Example 1 has a tensile strength of not less
than 300 MPa and an elongation of not less than 20%.
[0077] Note that the tensile strength and the elongation of the
produced aluminum alloy material are measured in conformity with
JIS Z-2241-2011. As illustrated in FIG. 1, in a plane defined by a
rolling direction along which the set of rolls 2 moves (final
working direction) and a transverse direction, tensile strengths
and elongations of the produced aluminum alloy material 1 are
measured in a 0.degree. direction, which is the rolling direction,
in a 45.degree. direction forming an angle of 45.degree. with the
0.degree. direction from the rolling direction toward the
transverse direction, and in a 90.degree. direction forming an
angle of 90.degree. with the 0.degree. direction from the rolling
direction toward the transverse direction. The tensile strength and
the elongation of the produced aluminum alloy material 1 are
defined respectively as the average value for the measured tensile
strengths and the average value for the measured elongations.
[0078] (Strength Anisotropy)
[0079] Tensile strengths are measured, in the plane defined by the
rolling direction (final working direction) and the transverse
direction, in the 0.degree. direction, which is the rolling
direction, in the 45.degree. direction forming an angle of
45.degree. with the 0.degree. direction from the rolling direction
toward the transverse direction, and in the 90.degree. direction
forming an angle of 90.degree. with the 0.degree. direction from
the rolling direction toward the transverse direction. The strength
anisotropy is defined as a standard deviation [MPa] calculated by
using the following Formula (1).
.times. ? = ? ? .times. ( TS i - TS ) 2 ( n - 1 ) .times. ( n
.gtoreq. 2 ) .times. .times. ? .times. indicates text missing or
illegible when filed Formula .times. .times. ( 1 ) ##EQU00001##
[0080] In the formula, TS.sub.i [MPa] represents a tensile strength
of each direction, TS [MPa] represents the average value for the
tensile strengths in the respective directions, and n represents
the total number of pieces of the tensile strength data.
[0081] (Crystallographic Texture)
[0082] The three-dimensional orientation analyzing method using the
crystallite orientation distribution function (ODF) described above
is applied to the aluminum alloy material of Example 1 to calculate
an orientation density. Specifically, a cross section of a portion
of the produced aluminum alloy material in a plane perpendicular to
the working direction (rolling direction) of the aluminum alloy
material is measured with an X-ray diffractometry. In this
measurement, after incomplete pole figures of the (111), (220), and
(200) planes are measured using the above Schlz reflection method
in an inclination angle range of 15 degrees to 90 degrees, a series
expansion is performed to determine the crystallite orientation
distribution function (ODF).
[0083] The orientation density of each orientation thus obtained is
calculated as a ratio with respect to the orientation density of a
standard sample having a random crystallographic texture. Table 2
shows results of evaluations performed such that an aluminum alloy
material having a {013}<100> orientation density of not more
than 5 and a {011}<100> orientation density of not more than
5 is rated as "G (good)" and an aluminum alloy material having a
{013}<100> orientation density exceeding 5 and a
{011}<100> orientation density exceeding 5 is rated as "P
(poor)". Further, an aluminum alloy material having a
{123}<634> orientation density of not more than 5 and a
{001}<100> orientation density of not more than 5 is rated as
"G", and an aluminum alloy material having the {123}<634>
orientation density exceeding 5 and the {001}<100>
orientation density exceeding 5 is rated as "P".
[0084] As shown in Table 2, it is understood that Example 1
successfully reduced strength anisotropy. In addition, Example 1
shows the results that indicate no problem with productivity.
COMPARATIVE EXAMPLES
[0085] As comparative examples to Example 1 described above, Table
4 shows properties of aluminum alloy materials produced by
performing a treatment similar to that for Example 1 on aluminum
alloys of Comparative Example 1 to Comparative Example 4 having
their respective compositions shown in Table 3. Note that, for
Comparative Examples 1 and 2, a treatment at 500.degree. C. and for
eight hours was performed as the homogenization treatment.
TABLE-US-00003 TABLE 3 Comparative Composition of Aluminum Alloy [%
by Mass] Example Fe Si Cu Mn Mg Cr Ti V Zr Ca Al Comparative 0.16
0.07 0.08 <0.01 6.2 <0.01 0.01 <0.01 <0.01 <0.01
Remaining Example 1 Percentage Comparative 0.16 0.07 0.08 <0.01
5.7 <0.01 0.01 <0.01 <0.01 <0.01 Remaining Example 2
Percentage Comparative 0.16 0.07 0.08 <0.01 11.0 <0.01 0.01
<0.01 <0.01 <0.01 Remaining Example 3 Percentage
Comparative 0.16 0.07 0.08 <0.01 9.0 <0.01 0.01 <0.01
<0.01 0.50 Remaining Example 4 Percentage
TABLE-US-00004 TABLE 4 Tensile Strength {001}<100>
{011}<100> {123}<634> {001}<100> Present Strength
Elongation Anisotropy Orientation Orientation Orientation
Orientation Invention [MPa] [%] [MPa] Density Density Density
Density Productivity Comparative 296 33 12 G G P P G Example 1
Comparative 288 33 11 G G P P G Example 2 Comparative -- -- -- --
-- -- -- P Example 3 Comparative -- -- -- -- -- -- -- P Example
4
[0086] Comparative Example 1, in which the content of Mg is too
low, results in a produced aluminum alloy material having a tensile
strength falling below the predetermined range, and thus fails to
yield good mechanical properties. In addition, since the
homogenization treatment temperature is too high, the strength
anisotropy exceeds the predetermined range, so that Comparative
Example 1 fails to yield good mechanical properties.
[0087] Comparative Example 2, in which the content of Mg is too
low, results in a produced aluminum alloy material having a tensile
strength falling below the predetermined range, and thus fails to
yield good mechanical properties. Further, since the homogenization
treatment temperature is too high, the strength anisotropy exceeds
the predetermined range, so that Comparative Example 2 fails to
yield good mechanical properties.
[0088] Comparative Example 3, in which the content of Mg is too
high, causes occurrence of cracking during the hot rolling. This
makes rolling difficult, so that the production is impossible.
[0089] Comparative Example 4, in which the content of Ca is too
high, causes occurrence of cracking during the hot rolling. This
makes rolling difficult, so that the production is impossible.
[0090] The present invention is not limited to the embodiments, but
can be altered by a skilled person in the art within the scope of
the claims. An embodiment based on a proper combination of
technical means disclosed in different embodiments is encompassed
in the technical scope of the present invention.
[0091] An aluminum alloy material in accordance with an aspect of
the present invention contains Mg: 7.0% to 10.0% (% by mass, the
same applies hereinafter) and Ca: not more than 0.1%, the aluminum
alloy material containing a remainder being constituted by aluminum
and an inevitable impurity, the aluminum alloy material having a
tensile strength of not less than 300 MPa and less than 500 MPa and
an elongation of not less than 20%.
[0092] The aluminum alloy material preferably contains Mn: 0.05% to
1.0%.
[0093] Further, the aluminum alloy material has a standard
deviation of tensile strengths of not more than 10, in a plane
defined by a final working direction and a transverse direction of
the aluminum alloy material, wherein the tensile strengths are a
tensile strength in a 0.degree. direction, which is the final
working direction, a tensile strength in a 45.degree. direction
forming an angle of 45.degree. with the 0.degree. direction from
the final working direction toward the transverse direction, and a
tensile strength in a 90.degree. direction forming an angle of
90.degree. with the 0.degree. direction from the final working
direction toward the transverse direction.
[0094] The aluminum alloy material preferably has a
{013}<100> orientation density of not more than 5 and a
{011}<100> orientation density of not more than 5, wherein
the {013}<100> orientation density and the {011}<100>
orientation density are calculated using a crystallite orientation
distribution function (ODF).
[0095] The aluminum alloy material preferably has a
{123}<634> orientation density of not more than 5 and a
{001}<100> orientation density of not more than 5, wherein
the {123}<634> orientation density and the {001}<100>
orientation density are calculated using a crystallite orientation
distribution function (ODF).
REFERENCE SIGNS LIST
[0096] 1 aluminum alloy material [0097] 2 roll
* * * * *