U.S. patent application number 13/988940 was filed with the patent office on 2013-09-12 for aluminum-magnesium alloy and method of producing the same.
This patent application is currently assigned to KOREA AUTOMOTIVE TECHNOLOGY INSTITUTE. The applicant listed for this patent is Beom Suck Han, Si Young Sung. Invention is credited to Beom Suck Han, Si Young Sung.
Application Number | 20130236351 13/988940 |
Document ID | / |
Family ID | 46146262 |
Filed Date | 2013-09-12 |
United States Patent
Application |
20130236351 |
Kind Code |
A1 |
Sung; Si Young ; et
al. |
September 12, 2013 |
ALUMINUM-MAGNESIUM ALLOY AND METHOD OF PRODUCING THE SAME
Abstract
Provided are an extruded aluminum (Al)-magnesium (Mg) material
and a method of producing the same. An Al--Mg master alloy having a
first Mg content is provided. An Al--Mg alloy having a second Mg
content less than the first Mg content is prepared by adding the
Al--Mg master alloy into molten Al and then casting the molten Al.
An extruded Al--Mg material is prepared by extruding the Al--Mg
alloy.
Inventors: |
Sung; Si Young;
(Chungcheongnam-do, KR) ; Han; Beom Suck;
(Gyeonggi-do, KR) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Sung; Si Young
Han; Beom Suck |
Chungcheongnam-do
Gyeonggi-do |
|
KR
KR |
|
|
Assignee: |
KOREA AUTOMOTIVE TECHNOLOGY
INSTITUTE
Chungcheongnam-do
KR
|
Family ID: |
46146262 |
Appl. No.: |
13/988940 |
Filed: |
November 21, 2011 |
PCT Filed: |
November 21, 2011 |
PCT NO: |
PCT/KR2011/008881 |
371 Date: |
May 22, 2013 |
Current U.S.
Class: |
420/407 ;
164/57.1; 420/542 |
Current CPC
Class: |
C22C 23/02 20130101;
B22D 21/007 20130101; B22D 25/00 20130101; C22C 21/06 20130101;
C22C 1/03 20130101 |
Class at
Publication: |
420/407 ;
164/57.1; 420/542 |
International
Class: |
C22C 21/06 20060101
C22C021/06; C22C 23/02 20060101 C22C023/02; B22D 25/00 20060101
B22D025/00 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 22, 2010 |
KR |
10-2010-0116442 |
Nov 22, 2010 |
KR |
10-2010-0116449 |
Nov 22, 2010 |
KR |
10-2010-0116451 |
Claims
1. A method of producing an aluminum (Al)-magnesium (Mg) alloy, the
method comprising: adding Mg into first molten Al; preparing an
Al--Mg master alloy having a first Mg content by casting the first
molten Al in which Mg is added; adding the Al--Mg master alloy into
second molten Al; and casting an Al--Mg alloy having a second Mg
content less than the first Mg content, by casting the second
molten Al.
2. The method of claim 1, wherein a holding time for melting the
Al--Mg master alloy in the adding of the Al--Mg master alloy is
less than the holding time for melting the Mg in the adding of the
Mg.
3. The method of claim 1, wherein a melting point of the Al--Mg
master alloy is less than the melting point of the Mg by 100 to
200.quadrature..
4. The method of claim 1, wherein the second Mg content is 2 to 12
wt %.
5. The method of claim 1, wherein the first Mg content is 5 to 40
wt %.
6. The method of claim 1, wherein an amount of a protective gas
used to prevent ignition of the Mg in the adding of the Mg is
greater than the amount of the protective gas used in the adding of
the Al--Mg master alloy.
7. The method of claim 1, wherein a protective gas is used to
prevent ignition of the Mg in the adding of the Mg, and wherein the
protective gas is not used in the adding of the Al--Mg master
alloy.
8. The method of claim 1, wherein an SF.sub.6 gas is not used as a
protective gas in the adding of the Al--Mg master alloy.
9. The method of claim 1, further comprising extruding the Al--Mg
alloy.
10. The method of claim 1, further comprising rolling the Al--Mg
alloy.
11. A method of producing an aluminum (Al)-magnesium (Mg) alloy,
the method comprising: providing an Al--Mg master alloy having a
first Mg content; adding the Al--Mg master alloy into molten Al;
and casting an Al--Mg alloy having a second Mg content less than
the first Mg content by casting the molten Al, wherein a melting
point of the Al--Mg master alloy is less than the melting point of
pure Mg by 100 to 200.quadrature..
12. The method of claim 11, wherein the adding of the Al--Mg master
alloy is performed without using a protective gas for preventing
ignition of Mg.
13. The method of claim 11, further comprising extruding or rolling
the Al--Mg alloy.
14. An aluminum (Al)-magnesium (Mg) alloy prepared by adding an
Al--Mg master alloy having a first Mg content into molten Al and
then casting the molten Al, so as to have a second Mg content less
than the first Mg content.
15. The Al--Mg alloy of claim 14, wherein the Al--Mg alloy has a
higher tensile strength and an equivalent or higher elongation in
comparison to a commercial Al--Mg alloy having a lower Mg
content.
16. The Al--Mg alloy of claim 14, wherein the first Mg content is 5
to 40 wt %, and the second Mg content is 2 to 12 wt %.
Description
TECHNICAL FIELD
[0001] The present invention relates to a technology of producing
an aluminum (Al) alloy, and more particularly, to an Al-magnesium
(Mg) alloy prepared by adding Mg as an alloying element, and a
method of producing the same.
BACKGROUND ART
[0002] Currently, magnesium (Mg) is regarded as one of main
alloying elements in an aluminum (Al) alloy. Addition of Mg allows
an Al alloy to have a high strength, to be favorable to surface
treatment, and to have improved corrosion resistance. As shown in
FIG. 1, Mg may be soluble in Al to about 17.4 weight percent (wt %)
at about 450.degree. C.
[0003] However, due to Mg having a chemically high oxidizing
potential, an oxide or another inclusion may be mixed into molten
Al during Mg is alloyed into the molten Al and thus the quality of
molten metal may deteriorate. If the amount of Mg added into molten
Al is added, a problem due to oxidation of Mg becomes serious. The
deterioration in quality of molten metal may greatly influence
properties of an alloy obtained by casting the molten metal.
[0004] For example, if molten Al having a poor quality die to a
high content of Mg is casted, casting cracks may be generated.
Also, an Al--Mg alloy prepared by casing the above molten Al has a
greatly reduced processability. For example, if the content of Mg
in the Al--Mg alloy is equal to or greater than 8.5 wt %,
industrially, processing is disabled.
[0005] Accordingly, when an Al--Mg alloy is prepared, in
consideration of castability and processability, in general, the
content of Mg is designed not to exceed 5 wt %. In order to prevent
an oxide or another inclusion from being mixed due to addition of
Mg, the surface of molten metal may be coated with a protective gas
such as an SF.sub.6 gas when Mg is added. However, the SF.sub.6 gas
not only is high-priced to increase costs but also causes an
environmental problem and thus is gradually restricted all over the
world. Accordingly, preparation of an Al--Mg alloy capable of
minimizing the use of an SF.sub.6 gas and having a high the content
of Mg is seriously required.
DETAILED DESCRIPTION OF THE INVENTION
Technical Problem
[0006] The present invention provides an aluminum (Al)-magnesium
(Mg) alloy capable of minimizing the use of a protective gas,
having excellent mechanical properties and a high processability,
and having a high the content of Mg, and a method of producing the
same. However, the present invention is not limited thereto.
Technical Solution
[0007] According to an aspect of the present invention, there is
provided a method of producing an aluminum (Al)-magnesium (Mg)
alloy. Mg is added into first molten Al. An Al--Mg master alloy
having a first Mg content is prepared by casting the first molten
Al in which Mg is added. The Al--Mg master alloy is added into
second molten Al. An Al--Mg alloy having a second Mg content less
than the first Mg content is casted by casting the second molten
Al.
[0008] A holding time for melting the Al--Mg master alloy in the
adding of the Al--Mg master alloy may be less than the holding time
for melting the Mg in the adding of the Mg.
[0009] A melting point of the Al--Mg master alloy may be less than
the melting point of the Mg by 100 to 200.degree. C.
[0010] The second Mg content may be 2 to 12 wt %. Also, the first
Mg content may be 5 to 40 wt %.
[0011] An amount of a protective gas used to prevent ignition of
the Mg in the adding of the Mg may be greater than the amount of
the protective gas used in the adding of the Al--Mg master alloy.
For example a protective gas may be used to prevent ignition of the
Mg in the adding of the Mg, and the protective gas may not be used
in the adding of the Al--Mg master alloy.
[0012] The method may further include extruding or rolling the
Al--Mg alloy.
[0013] According to another aspect of the present invention, there
is provided an aluminum (Al)-magnesium (Mg) alloy prepared by
adding an Al--Mg master alloy having a first Mg content into molten
Al and then casting the molten Al, so as to have a second Mg
content less than the first Mg content.
[0014] The Al--Mg alloy has a higher tensile strength and an
equivalent or higher elongation in comparison to a commercial
Al--Mg alloy having a lower Mg content.
Advantageous Effects
[0015] According to embodiments of the present invention, an
aluminum (Al)-magnesium (Mg) alloy having a very good castability
may be produced by preparing an Al--Mg master alloy having a high
content of Mg and then diluting the Al--Mg master alloy without
using a protective gas or using a small amount of the protective
gas.
[0016] The above-prepared Al--Mg alloy and a processed material
(for example, an extruded material or a rolled material) thereof
may have excellent mechanical properties (for example, a high
strength and excellent elongation properties) in comparison to a
conventional commercial Al alloy and a processed material
thereof.
[0017] The effects of the present invention are not limited to the
above-described effects and other effects not described above may
be understood by one of ordinary skill in the art from the
following detailed description of the invention.
DESCRIPTION OF THE DRAWINGS
[0018] FIG. 1 is a graph showing an aluminum (Al)-magnesium (Mg)
state.
[0019] FIG. 2 is a flowchart of a method of producing an Al--Mg
alloy, according to the present invention.
[0020] FIGS. 3A and 3B are images showing the surfaces of residual
metal in cases when an SF.sub.6 gas is not used and is used as a
protective gas.
[0021] FIGS. 4A and 4B are images showing the states after an
Al--Mg alloy prepared according to the present invention and a
conventional Al--Mg alloy are extruded.
[0022] FIG. 5A and FIG. 5B are an image and a graph showing a
microstructure and a tensile test result of an Al--Mg alloy casted
according to the present invention.
[0023] FIG. 6 is a graph comparatively showing mechanical
properties of an Al--Mg alloy casted according to the present
invention and a 5052 Al alloy after they are extruded.
[0024] FIG. 7 is an image showing a microstructure of an Al--Mg
alloy casted according to the present invention after it is
extruded.
[0025] FIG. 8 is a graph comparatively showing mechanical
properties of an Al--Mg alloy casted according to the present
invention and a 5052 Al alloy after they are rolled.
[0026] FIG. 9 is an image showing a microstructure of an Al--Mg
alloy casted according to the present invention after it is
rolled.
MODE OF THE INVENTION
[0027] Hereinafter, the present invention will be described in
detail by explaining embodiments of the invention with reference to
the attached drawings. The invention may, however, be embodied in
many different forms and should not be construed as being limited
to the embodiments set forth herein; rather, these embodiments are
provided so that this disclosure will be thorough and complete, and
will fully convey the concept of the invention to one of ordinary
skill in the art. In the drawings, the thicknesses of layers and
regions are exaggerated for convenience of explanation.
[0028] If a weight percent (wt %) range is greater or less than a
certain value, it may not include the value and may be merely
designated as a range. If the range is equal to or greater or less
than a certain value, it may include the value.
[0029] FIG. 2 is a flowchart of a method of producing an aluminum
(Al)-magnesium (Mg) alloy, according to embodiments of the present
invention.
[0030] Initially, molten Al for producing an Al--Mg master alloy is
provided (S1). In this case, the molten Al provided to form an
Al--Mg master alloy may be referred to as first molten Al.
Meanwhile, molten Al provided to add the Al--Mg master alloy in the
description below may be referred to as second molten Al in order
to be distinguished from the first molten Al.
[0031] In this case, a master alloy refers to an alloy prepared to
be added into molten metal provided in a subsequent process, and a
resultant material prepared by adding the master alloy is referred
to as an alloy in order to be distinguished from the master alloy.
Accordingly, in the present invention, an alloy prepared by adding
a prepared Al--Mg master alloy to molten Al is referred to as an
Al--Mg alloy.
[0032] Then, Mg is added into the first molten Al and then is
melted (S2). In this case, in consideration of a ratio that the
added Mg is to be diluted in the second molten Al, the content of
the added Mg may be set to be higher than the content of Mg in a
typical Al--Mg alloy.
[0033] When an Al--Mg master alloy is prepared, a top surface of
the Mg-added first molten Al may be protected by using a protective
gas. The protective gas may be SF.sub.6, SO.sub.2, CO.sub.2,
HFC-134A, Novec.TM. 612, an inert gas, an equivalent thereof, or a
gas mixture thereof. If a high content of Mg is added into the
molten Al, the protective gas may prevent an oxide or other
impurities from being formed in the molten Al due to a phenomenon
that Mg in the molten Al reacts with oxygen in the air and thus is
ignited.
[0034] FIGS. 3A and 3B are images showing the surfaces of residual
metal in cases when an SF.sub.6 gas is not used and is used as a
protective gas and 6 wt % of Mg is added into the molten Al.
Referring to FIG. 3A, when the SF.sub.6 gas is not used, the
residual metal turns black due to oxidation of Mg. On the other
hand, referring to FIG. 3B, when the SF.sub.6 gas is used, the
residual metal is hardly oxidized.
[0035] The Mg-added first molten Al may be stirred by using an
appropriate means. For example, it may be mechanically stirred by
using a stirring means provided under a furnace or may be stirred
by using an electromagnetic stirring means provided outside the
furnace.
[0036] After Mg is sufficiently melted, an Al--Mg master alloy is
prepared by casting the first molten Al in a mold (S3). In this
case, the mold may be one selected from a metallic mold, a ceramic
mold, a graphite mold, and an equivalent thereof. Also, the casting
method may include sand casting, die casting, gravity casting,
continuous casting, low-pressure casting, squeeze casting, lost wax
casting, thixo casting, or the like. However, the present invention
does not limit the type of a mold and a method of casting.
[0037] The above-prepared Al--Mg master alloy is added into the
second molten Al as a source of Mg.
[0038] In more detail, the second molten Al is prepared (S4) and
the prepared Al--Mg master alloy is added (S5). In this case, a
melting point of the Al--Mg master alloy is reduced in comparison
to pure Mg as shown in the graph of FIG. 1.
[0039] For example, if the content of Mg in the Al--Mg master alloy
is about 38 wt %, the melting point of the Al--Mg master alloy is
reduced in comparison to the melting point of pure Mg (651.degree.
C.) by about 200.degree. C. The melting point of the Al--Mg master
alloy may be determined according to the content of Mg and may be
lower than the melting point of pure Mg by about 100 to 200.degree.
C. in consideration of a melting time. The content of Mg in the
Al--Mg master alloy may be appropriately adjusted and thus the
above-mentioned range of reduction in melting point may be
appropriately selected.
[0040] Accordingly, the Al--Mg master alloy added into the second
molten Al may be melted at a relatively lower temperature in
comparison to Mg added into the first molten Al. Due to the above
reduction in melting point, Mg may be fast and easily melted in the
second molten Al. As described above, if the melting point of the
Al--Mg master alloy is greatly lowered, a holding time for melting
the Al--Mg master alloy may be less than the holding time for
melting Mg in the first molten Al. As such, a processing time may
be reduced.
[0041] Also, when the Al--Mg master alloy is added into the second
molten Al, since Mg is added after Mg is completely alloyed with
Al, the amount of a protective gas may be greatly reduced in
comparison to the case when Mg is added into the first molten Al.
Further, when the Al--Mg master alloy is added, although a
protective gas such as SF.sub.6 is not used, ignition of Mg in the
second molten Al is greatly reduced. Accordingly, molten Al
including Mg may be maintained clean without using a protective gas
such as an SF.sub.6 gas that causes an environmental problem and is
high-priced. Since Mg is added into molten Al in the form of an
Al--Mg master alloy, a high content of Mg may be stably added
without causing a problem caused when Mg is directly added into the
molten Al.
[0042] Stirring may be performed to sufficiently melt the Al--Mg
master alloy added into the second molten Al. The stirring is
already described above and thus is not described in detail
here.
[0043] An Al--Mg alloy is prepared by sufficiently melting and then
casting the Al--Mg master alloy in the second molten Al (S6). The
casting method is already described above and thus is not described
in detail here.
[0044] According to the present invention, the content of Mg added
into the second molten Al may be calculated by using the amount of
Al in the second molten Al before the Al--Mg master alloy is not
added, and the contents of Al and Mg in the Al--Mg master
alloy.
[0045] That is, when the Al--Mg master alloy is added into the
second molten Al, Mg in the Al--Mg master alloy is diluted and the
content of the diluted Mg may be represented as shown in the
following mathematical expression.
W Mg ( W m g + W A / 1 + W A / 2 ) [ Mathematical Expression ]
##EQU00001##
[0046] Here, W.sub.Mg and W.sub.Al1 are the weights of Mg and Al in
the Al--Mg master alloy, and W.sub.Al2 is the weight of Al in the
second molten Al.
[0047] A desired content of Mg in the second molten Al may be
achieved by using the above mathematical expression.
[0048] In the present invention, the content of Mg in the Al--Mg
master alloy has a relatively high value in comparison to that in
the Al--Mg alloy, and the Al--Mg alloy has a relatively low content
of Mg due to dilution according to the above mathematical
expression.
[0049] For example, the content of Mg in the Al--Mg master alloy
may have a range of 5 to 40 wt %, and the content of Mg diluted in
the Al--Mg alloy may have a range of 1 to 15 wt % range, and
particularly, 2 to 12 wt %, and more particularly, 5 to 10 wt %.
The content of Mg in the Al--Mg alloy may be constantly maintained
in an extruded material prepared by extruding the Al--Mg alloy.
[0050] According to the present invention, an Al--Mg master alloy
having a high content of Mg may be prepared first, and then an
Al--Mg alloy as much as an inverse ratio of a dilution ratio of the
Al--Mg master alloy may be prepared. For example, when 100 g of an
Al--Mg master alloy having 40 wt % of Mg is prepared, if a dilution
ratio is 0.25, a total of 400 g of an Al--Mg alloy having 10 wt %
of Mg may be prepared.
[0051] In this case, a protective gas is used only when the Al--Mg
master alloy is prepared. After the Al--Mg master alloy is
prepared, the protective gas does not need to be used to prepare
the Al--Mg alloy by diluting the Al--Mg master alloy. Accordingly,
an Al--Mg alloy having a high content of Mg may be easily prepared
by minimizing the use of a protective gas such as an SF.sub.6 gas
that is high-priced and causes an environmental problem.
[0052] A processed material (or a wrought material) prepared by
processing the Al--Mg alloy casted according to the present
invention has superior mechanical properties to a conventional
commercial alloy. For example, the Al--Mg alloy according to an
embodiment of the present invention may be provided as a processed
material such as an extruded Al--Mg material or a rolled Al--Mg
material.
[0053] The extruded Al--Mg material may be prepared by extruding
the above-described Al--Mg alloy by using an extrusion apparatus.
For example, the Al--Mg alloy may be put into a container, may be
passed through dies by using a stem, and thus may be extruded to a
predetermined shape. The extruded Al--Mg material may be prepared
in various shapes, for example, a rod shape or a plate shape.
[0054] Since the Al--Mg alloy having a high content of Mg and a
high casting quality is used, if process-hardening is added due to
extrusion, the extruded Al--Mg material may have an excellent
processability as well as excellent tensile strength
properties.
[0055] The rolled Al--Mg material may be prepared by rolling the
above-described Al--Mg alloy by using a rolling apparatus. For
example, the Al--Mg alloy may be loaded between rollers and may be
rolled to a predetermined shape by rotating the rollers.
[0056] Since the Al--Mg alloy having a high content of Mg and a
high casting quality is used, if process-hardening is added due to
rolling, the rolled Al--Mg material may have an excellent
processability as well as excellent tensile strength
properties.
[0057] Examples will now be provided for better understanding of
the present invention. However, the following examples are provided
merely to achieve better understanding of the present invention and
do not limit the present invention.
[0058] FIGS. 4A and 4B are images showing extrusion states when an
Al--Mg alloy prepared by diluting an Mg--Al master alloy according
to the present invention (Example 1) and an Al--Mg alloy prepared
by directly adding Mg (Comparative Example 1) are extruded.
[0059] In this case, the content of Mg in both of Example 1 and
Comparative Example 1 is 10 wt %, and the content of Mg in the
Al--Mg master alloy used in Example 1 is 38 wt %. Also, in both of
Example 1 and Comparative Example 1, molten metal is continuous
casted and then extruded to a form of a rod having a
cross-sectional diameter of 180 mm.
[0060] Referring to FIGS. 4A and 4B, Example 1 shows a very good
extruded material having no cracks or abnormal defects. On the
other hand, Comparative Example 1 shows that serious damage is
caused due to a plurality of casting cracks generated during
extrusion.
[0061] As such, it is shown that, in comparison to the Al--Mg alloy
prepared by using a conventional method, the Al--Mg alloy prepared
according to the present invention has a very good processability
in spite of a high content of Mg, for example, 10 wt %. Therefore,
according to the present invention, an Al--Mg alloy having a high
content of Mg, for example, 5 wt % or above, which was not
substantially commercialized due to a poor processability, may be
prepared with an excellent processability.
[0062] In Example 1, since Mg is added into molten Al in the form
of the Al--Mg master alloy, although a protective gas such as an
SF.sub.6 gas is not used, the molten Al may be maintained in a very
good state and thus the Al--Mg alloy may also be in a very good
state after being casted. Accordingly, considering that the Al--Mg
alloy having a high content of Mg, for example, 10 wt %, is
prepared without using a protective gas such as an SF.sub.6 gas in
Example 1, the method of producing an Al--Mg alloy, according to
the present invention, is very economical and efficient.
[0063] FIG. 5A and FIG. 5B are an image and a graph showing a
microstructure and a tensile test result of an Al--Mg alloy casted
according to the present invention.
[0064] FIG. 5A is an optical microscopic image of an internal
structure of an Al--Mg alloy prepared by using the same method used
in Example 1 except that mold casting is performed (Example 2).
Referring to FIG. 5A, the Al--Mg alloy of Example 2 has a very good
structure in which an impurity such as an oxide or another
inclusion generated due to oxidation of Mg in molten metal is not
found.
[0065] The Al--Mg alloy of Example 2 has remarkably superior
mechanical properties to a commercial Al--Mg alloy. FIG. 5B shows
tensile properties of the Al--Mg alloy of Example 2, and Table 1
shows mechanical properties of the Al--Mg alloy of Example 2 and an
AC7A-F alloy that is a commercial Al--Mg casting alloy, according
to the KS D 6008 standards.
TABLE-US-00001 TABLE 1 Content of Mg Tensile Strength (MPa)
Elongation (%) Example 2 10 wt % 233 12 AC7A-F 3.5 to 5.5 wt % 210
12
[0066] As shown in FIG. 5B and Table 1, the Al--Mg alloy of Example
2 has a superior tensile strength and an equivalent elongation to
the AC7A-F alloy.
[0067] In the Al--Mg alloy prepared by using a conventional method,
if Mg is increased to a high content, casting cracks are generated
and thus a poor elongation is achieved. However, the Al--Mg alloy
of Example 2 has a high content of Mg (10 wt %) more than double
that of the AC7A-F alloy and has a superior tensile strength and an
equivalently excellent elongation to the AC7A-F alloy.
[0068] Considering that the Al--Mg alloy having a high content of
Mg, for example, 10 wt %, is prepared without using a protective
gas such as an SF.sub.6 gas in Example 2, the method of producing
an Al--Mg alloy, according to the present invention, is very
economical and efficient.
[0069] FIG. 6 is a graph showing tensile test results of an
extruded material prepared by extruding the Al--Mg alloy of Example
2 (Example 3), and an extruded material prepared by extruding a
5052 alloy that is a commercial Al alloy. Table 2 shows mechanical
properties of the extruded material of Example 3 and the extruded
material of the 5052 alloy.
TABLE-US-00002 TABLE 2 Tensile Strength Yield Strength (MPa) (MPa)
Elongation (%) Example 3 399 221 38.2 Extruded Material 211 87 23.7
of 5052
[0070] Referring to FIG. 6 and Table 2, the extruded material of
Example 3 has remarkably superior mechanical properties to the
extruded material of the 5052 alloy. That is, the extruded material
of Example 3 has a greatly higher tensile strength and a quite
higher elongation than the extruded material of the 5052 alloy.
[0071] As described above, since processability is greatly reduced
if the content of Mg in an Al--Mg alloy is high, a 5000-series
alloy that is a commercial Al--Mg alloy for preparing a processed
material is designed to have a content of Mg less than 5.5 wt %.
However, the extruded material of Example 3 in which the content of
Mg is 10 wt % has remarkably superior elongation and strength
properties to the extruded material of the 5052 alloy in which the
content of Mg is 2.2 to 2.8 wt %.
[0072] FIG. 7 is an optical microscopic image of a microstructure
of the extruded material of Example 3. As shown in FIG. 7, the
extruded material of Example 3 has a microstructure in which very
fine grains are uniformly distributed. These excellent mechanical
properties of the extruded material may be achieved due to a
combination of good mechanical properties of a casting alloy having
a high solubility of Mg and an effect of a microstructure in which
fine grains are uniformly distributed after being processed.
[0073] FIG. 8 is a graph showing tensile test results of a rolled
material prepared by rolling to the Al--Mg alloy of Example 2
(Example 4), and a rolled material prepared by rolling a 5052 alloy
that is a commercial Al alloy. Table 3 shows contents and
mechanical properties of the rolled material of Example 4 and the
rolled material of the 5052 alloy. In this case, a reduction ratio
of the rolling process is 83%.
TABLE-US-00003 TABLE 3 Tensile Strength Yield Strength (MPa) (MPa)
Elongation (%) Example 4 563 489 18.1 Rolled Material of 220 203
13.2 5052
[0074] As shown in FIG. 8 and Table 3, the rolled material of
Example 4 has remarkably superior tensile strength, yield strength,
and elongation to the rolled material of the 5052 alloy. That is,
the rolled material of Example 4 has a higher tensile strength and
a higher elongation than the rolled material of the 5052 alloy
having a low content of Mg.
[0075] As described above, since processability is greatly reduced
if the content of Mg in an Al--Mg alloy is high, a 5000-series
alloy that is a commercial Al--Mg alloy for preparing a processed
material is designed to have a content of Mg less than 5.5 wt %.
However, the rolled material of Example 4 in which the content of
Mg is 10 wt % has remarkably superior elongation and strength
properties to the rolled material of the 5052 alloy in which the
content of Mg is 2.2 to 2.8 wt %.
[0076] FIG. 9 is an optical microscopic image of a microstructure
of the rolled material of Example 4. As shown in FIG. 9, the rolled
material of Example 4 has a microstructure in which very fine
grains are uniformly distributed. These excellent mechanical
properties of the rolled material may be achieved due to a
combination of good mechanical properties of a casting alloy having
a high solubility of Mg and an effect of a microstructure in which
fine grains are uniformly distributed after being processed.
[0077] The above-described Al--Mg alloy and the method of producing
a processed material of the Al--Mg alloy, according to embodiments
of the present invention, may be applied to various Al alloys and
processed materials prepared by processing them. For example, when
a casting alloy based on an Al--Mg alloy or a 5000-series or
6000-series Al--Mg alloy for a processed material is prepared, by
adding Mg in the form of an Al--Mg master alloy instead of directly
adding Mg, oxidation of Mg in molten Al may be prevented and thus
excellent castability or mechanical properties may be ensured.
[0078] While the present invention has been particularly shown and
described with reference to exemplary embodiments thereof, it will
be understood by those of ordinary skill in the art that various
changes in form and details may be made therein without departing
from the spirit and scope of the present invention as defined by
the following claims.
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