U.S. patent application number 12/796328 was filed with the patent office on 2011-03-31 for novel aluminum alloy and produts thereof.
This patent application is currently assigned to GOLDEN DRAGON PRECISE COPPER TUBE GROUP, INC.. Invention is credited to Hongwei Qiu, Jianguo Wang, Xueyin Wang, Jinli Zhang.
Application Number | 20110076184 12/796328 |
Document ID | / |
Family ID | 42417033 |
Filed Date | 2011-03-31 |
United States Patent
Application |
20110076184 |
Kind Code |
A1 |
Zhang; Jinli ; et
al. |
March 31, 2011 |
NOVEL ALUMINUM ALLOY AND PRODUTS THEREOF
Abstract
The present invention provides a high corrosion resistant
aluminum alloy consisting essentially of (by weight %): 0.30-1.25%
Mn, 0.10-1.20% Si, 0.05-0.25% Cr, 0.05-0.2% Zr, 0.08-0.30% Ti, less
than 0.03% Zn, less than 0.03% Cu, and up to 0.20% Fe, balance
aluminum and inevitable impurities. The present invention also
relates to articles made of the alloy.
Inventors: |
Zhang; Jinli; (Xinxiang
City, CN) ; Wang; Jianguo; (Xinxiang City, CN)
; Qiu; Hongwei; (Xinxiang City, CN) ; Wang;
Xueyin; (Xinxiang City, CN) |
Assignee: |
GOLDEN DRAGON PRECISE COPPER TUBE
GROUP, INC.
Xinxiang City
CN
|
Family ID: |
42417033 |
Appl. No.: |
12/796328 |
Filed: |
June 8, 2010 |
Current U.S.
Class: |
420/531 ;
420/537 |
Current CPC
Class: |
C22C 21/02 20130101;
C22C 21/00 20130101; F28F 21/084 20130101 |
Class at
Publication: |
420/531 ;
420/537 |
International
Class: |
C22C 21/18 20060101
C22C021/18; C22C 21/10 20060101 C22C021/10; C22C 21/02 20060101
C22C021/02; C22C 21/14 20060101 C22C021/14 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 29, 2009 |
CN |
200910177463.4 |
Claims
1. A high corrosion resistant aluminum alloy consists essentially
of (by weight %): 30-1.25% Mn; 10-1.20% Si; 0.05-0.25% Cr;
0.05-0.20% Zr; 08-0.30% Ti; less than 0.03% Zn; less than 0.03% Cu;
and up to 0.20% Fe; balance aluminum and inevitable impurities.
2. The alloy of claim 1, wherein Mn content is preferably
0.50-1.00%, and more preferably 0.70-0.90%.
3. The alloy of claim 1, wherein Si content is preferably
0.20-0.80%, and more preferably 0.30-0.60%.
4. The alloy of claim 1, wherein Cr content is preferably
0.06-0.18%, and more preferably 0.08-0.12%.
5. The alloy of claim 1, wherein Zr content is preferably
0.08-0.20%, and more preferably 0.10-0.15%.
6. The alloy of claim 1, wherein Ti content is preferably
0.10-0.25%, and more preferably 0.12-0.20%.
7. The alloy of claim 1, wherein Fe content is preferably up to
0.15%, and more preferably up to 0.10%.
8. Article in the form of pipes, wires, stripes, rods, plates or
bars, characterized in that the article is made of an alloy
according to claim 1.
9. The article of claim 8, wherein the article is a material for a
heat exchanger.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application claims the benefit of Chinese Patent
Application No. 200910177463.4, filed Sep. 29, 2009, which is
incorporated herein by reference in its entirety.
TECHNICAL FIELD
[0002] The present invention relates to a novel corrosion resistant
aluminum alloy and articles thereof, particularly to an AA3000
series aluminum alloy and articles thereof.
BACKGROUND ART
[0003] 1XXX series pure aluminum exhibits excellent formability and
weld properties. Its corrosion resistance is the best among
aluminum alloys, but its strength is relative low. 3XXX series
aluminum alloy are manufactured by adding Mn in aluminum to form a
solid solution so as to strengthen aluminum alloy, enhance the
strength of aluminum alloy, maintain good corrosion resistance,
electrical conductivity, thermal conductivity, and have excellent
welding property and plastic processing property. 3XXX series
aluminum alloys have been widely used in automobiles, refrigerating
equipments, chemical industry and so on for manufacturing radiating
pipes and radiating fins of heat exchangers.
[0004] In the past 15 years, standard 3003 aluminum alloy was used
generally. This alloy has good formability and mechanical
properties, and acceptable corrosion resistance. Recently, with the
continuous improvement of aluminum heat exchangers in structure
design, the thickness of brazed aluminum alloy pipes has been
reduced gradually from 1 mm to not more than 0.4 mm. Studies have
shown that the corrosion behavior of aluminum alloys for heat
exchangers mainly includes two mechanism, that is pitting corrosion
and grain boundary corrosion. If the phases in the alloy are closer
to aluminum matrix in electrical potential, their number is less,
and their distribution is more uniform, then the corrosion
resistance property of the alloy is better. With the improvement of
the structure of refrigerating components, the materials of
aluminum alloy pipes for heat exchangers have been developed from
1XXX pure aluminum (e.g. 1050, 1060, 1100, 1235) to 3XXX series
aluminum alloys (e.g. 3003, 3005, 3102, 3104 and so on), and the
thickness of the wall of the pipes has been reduced gradually from
1 mm to not more than 0.4 mm; the outer surface of the pipe was
coated by using multiple coating technologies to enhance the
corrosion resistance properties of the pipes.
[0005] In order to solve the problems that the strength and the
corrosion resistance of alloys should be correspondingly improved
due to the reduction of the wall thickness of the pipes, 3026
aluminum alloy has been developed in the prior art. This alloy was
manufactured by optimizing the composition of the alloy based on
corrosion resistance and processability. The optimization includes:
exactly adjusting the amounts of each alloying element, such as,
reducing the amounts of Mn and Fe in the alloy and simultaneously
adding Cu, Zn, Ti and adjusting the amounts thereof, to make the
electrical potential of the phases in the alloy close to that of
aluminum matrix so as to enhance the corrosion resistance of the
alloy and ensure that the alloy has certain mechanical properties,
processabilities and excellent welding properties. However, it has
been found in practical use that the alloy exhibits disadvantageous
deep processing properties due to poor mechanical properties, as
compared to 3003 alloy.
[0006] Studies have shown that addition of small amounts of Cr, Mn,
Zr, Ti, Si, etc. into aluminum can reduce the pitting corrosion of
alloys, while decreasing and controlling Fe, Cu, Ni and so on can
effectively enhance the corrosion resistance of alloys, and
appropriately increasing the amounts of special alloying elements
to form a greater amount of reinforcing phases so as to prevent the
coarsening of grains in hot working and heat treatment thereby
refining microstructure. 3XXX series alloys with Cr and Zr added
therein may cause the formation of dispersed phases such as
Al(MnFeCr)Si or Al(FeMnCr)Si and Al.sub.3Zr, etc. during
homogenization. As the amount of the dispersed phases is increased,
the recrystallization temperature of alloys is elevated. Very high
density and thermal stability of these dispersed phases will
seriously affect the recovery, recrystallization and growth of
grains during the solution heating of alloys, even can act as
nucleation site for the precipitation of reinforcing phases. It has
been proved that dispersed phases can promote homogeneous sliding,
enhance the strength, plasticity and bending properties of aluminum
alloys, and prevent the growth of recrystallized grains by pinning
the migration of grain boundaries, and the effective action of the
refining of grains thereof increase in the order of Cr, Mn, Zr.
Fine grain structures benefit the enhancement of mechanical
properties and corrosion resistance properties of alloys, however,
excessive Cr will render the degradation of processability of
alloys. Ti is an effective grain refiner. Studies have shown that
in addition to serving as a heterogeneous nucleus to promote the
nucleation, it is also distributed in grain boundary to inhibit the
growth of .alpha.(Al) grains so as to effectively refine structure
and improve formability.
[0007] In summary, there are still demands of aluminum alloys
having excellent mechanical strength and corrosion resistance in
this art.
[0008] The present invention uses following technical solutions: on
the basis of Al--Mn alloy, reducing the amounts of Fe, Cu and Zn in
the alloy, adjusting the amounts of Si and Mn in the alloy, and
adding Cr, Zr and Ti to the alloy in combination. At the meantime,
the production process should guarantee that the products achieve
stable fine grain fiber structure, the alloying elements in the
grain are sufficiently solutionized and disadvantageous
precipitation phases do not occur in grain boundary, and the
products have higher corrosion resistance and good mechanical
properties or formability.
SUMMARY OF THE INVENTION
[0009] In one aspect, the present invention provides a novel
aluminum alloy which satisfies the demands mentioned above. In
order to solve the problem that the strength and corrosion
resistance of alloy should be enhanced correspondingly brought by
the reduction of the thickness of the wall of cooling pipe
materials, the present invention achieves high corrosion resistance
and good mechanical properties and technological properties by
reducing the amounts of Fe, Cu and Zn, adjusting the amounts of Si
and Mn, and adding Cr, Zr, Ti, etc. in combination on the basis of
the composition of Al--Mn series alloys.
[0010] The alloy of the present invention consists essentially of
(by weight %): 0.30-1.25% Mn, 0.10-1.20% Si, 0.05-0.25% Cr,
0.05-0.20% Zr, 0.08-0.30% Ti, less than 0.03% Zn, less than 0.03%
Cu, and up to 0.20% Fe, balance aluminum and inevitable
impurities.
[0011] In the embodiments of the present invention, the Mn content
in the alloy of the present invention is preferably 0.50-1.00%, and
more preferably 0.70-0.90%.
[0012] In the embodiments of the present invention, the Si content
in the alloy of the present invention is preferably 0.20-0.80%, and
more preferably 0.30-0.60%.
[0013] In the embodiments of the present invention, the Cr content
in the alloy of the present invention is preferably 0.06-0.18%, and
more preferably 0.08-0.12%.
[0014] In the embodiments of the present invention, the Zr content
in the alloy of the present invention is preferably 0.08-0.20%, and
more preferably 0.10-0.15%.
[0015] In the embodiments of the present invention, the Ti content
in the alloy of the present invention is preferably 0.10-0.25%, and
more preferably 0.12-0.20%.
[0016] In the embodiments of the present invention, the Fe content
in the alloy of the present invention is preferably up to 0.15%,
and more preferably up to 0.10%.
[0017] The aluminum alloys of the present invention are adapted to
be made into various forms of articles, including but being not
limited to the articles in the form of pipes, wires, strips,
plates, sheets or rods. Preferably, the inventive aluminum alloys
are particularly suitable for using as materials for heat
exchangers.
BRIEF DESCRIPTION OF THE DRAWINGS
[0018] The present invention will be described in detail with
reference to following drawings.
[0019] FIG. 1 shows the Comparative pictures of metallographic
microstructure of present inventive alloy and 3003 alloy after the
SWAAT corrosion resistance performance testing for 10 days, wherein
the left side shows 3003 alloy, and the right side shows the
inventive alloy.
[0020] FIG. 2 shows the SEM (Scanning Electron Microscope) pictures
of present inventive alloy and 3003 alloy after subjecting to
corrosion for 20 days, wherein the left side shows 3003 alloy, and
the right side shows the inventive alloy.
[0021] FIG. 3 shows the true stress-strain plot obtained on Gleeble
1500 thermal dynamic simulator by using the cylindrical isothermal
hot compression testing process.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
[0022] In the context of the present invention, as to the
composition of the aluminum alloys, all the percents mentioned mean
weight percent (wt %) unless indicated otherwise. Besides, the
nomenclature of the aluminum or aluminum alloys referred to in the
present invention means the nomenclature of Aluminum Association
(AA).
[0023] Additionally, when any numerical value range is referred to,
it should be understood that this range includes each number and/or
subrange between the minimum and maximum in said range. For
example, the range of 0.30-1.25% Mn should include all intermediate
values, e.g. 0.31%, 0.32%, 0.33%, . . . 1.23%, 1.24% and 1.25% Mn.
This is also suitable for the ranges of all other elements
mentioned below.
[0024] Present invention obtained an aluminum alloy with excellent
corrosion resistance and good mechanical performance by decreasing
the contents of Fe, Cu and Zn, adjusting the contents of Si and Mn,
and adding Cr, Zr and Ti, etc. in combination on the basis of the
composition of Al--Mn series alloy. The basic composition of the
inventive alloy is (by weight %): 0.30-1.25% Mn, 0.10-1.20% Si,
0.05-0.25% Cr, 0.05-0.20% Zr, 0.08-0.30% Ti, less than 0.03% Zn,
less than 0.03% Cu, and up to 0.20% Fe, balance aluminum and
inevitable impurities.
[0025] Mn can prevent the recrystallization of aluminum and its
alloys, elevate recrystallization temperature, and can refine the
grains of recrystallization significantly. At the meantime, Mn can
enhance the strength of the alloys, but excessive Mn may form
coarse compounds and damage the properties of materials. Hence, Mn
content should be 0.30-1.25%, preferably 0.5-1.00%, and more
preferably 0.70-0.90%.
[0026] Si can reduce the solubility of Mn in aluminum, accelerate
the precipitation of Mn from supersaturated solid solution during
thermal deformation, and improve the mechanical properties of
alloys. Therefore, Si content is required to be between 0.10% and
1.20%, preferably between 0.20% and 0.80%, and more preferably
between 0.30% and 0.60%.
[0027] Cr is an alloying element commonly used in aluminum alloys.
It can hinder the nucleation and the growth of recrystallized
grains, refine the recrystallized grains, strengthen the alloys,
and simultaneously improve the toughness of the alloys and reduce
stress corrosion cracking sensitivity, but increase the quenching
sensitivity. Additionally, the addition of Cr in the aluminum
alloys is generally not greater than 0.35%. Hence, Cr content
should be 0.05-0.25%, preferably 0.06-0.18%, and more preferably
0.08-0.12%.
[0028] Ti can refine cast structure and weld structure remarkably,
reduce cracking tendency, and enhance the mechanical properties of
materials. Hence, Ti content should be 0.08-0.30%, preferably
0.10-0.25%, and more preferably 0.12-0.20%.
[0029] Zr can also refine cast microstructure, exhibit less
quenching sensitivity than Cr and Mn, but decrease the grain
refinement effect of Ti. Thus, a small amount of Zr is used to
substitute Cr and Mn for refining recrystallized microstructure and
reducing the quenching sensitivity of the alloys. Therefore, Zr
content is required to be 0.05-0.20%, and preferably
0.10-0.15%.
[0030] Zn has no significant affect on the mechanical properties
and corrosion resistance of the alloys, but exhibits disadvantages
to the weldability of the alloys. In order to enhance the
weldability of materials, Zn content should be less than 0.03%.
[0031] Cu can enhance the tensile strength of the alloys
significantly, however, a small amount of Cu will decrease the
corrosion resistance of the alloys. Thus, Cu content should be not
greater than 0.03%.
[0032] Fe can effectively refine the annealed grains, but excessive
Fe may form a great deal of coarse platlet intermediate phase
compounds, and decrease the corrosion resistance of the alloys
remarkably. Hence, Fe content is required to be up to 0.2%.
[0033] The aluminum alloys according to the present invention have
excellent corrosion resistance and mechanical strength, are
suitable for making the articles in various forms of pipes, wires,
strips, plates, sheets or rods. Particularly, the inventive alloys
are suitable for using as materials for heat exchangers.
EXAMPLES
[0034] The present invention is further described by following
examples. It should be indicated that following examples are only
used to illustrate the present invention, but not intended to limit
the present invention in any way.
Example 1
[0035] According to the alloy composition of present invention,
99.7Al ingot and Al-10Mn, Al-12Si, Al--SCr, Al-10Zr, Al-10Ti
intermediate alloys were used to make an alloy according to the
weight % described as follows: Al-1.2Mn-0.2Si-0.15Cr-0.15Zr-0.15Ti,
which was named as alloy A-1 (the composition of the alloy is shown
in Table 1). The alloy was smelt and refined in a graphite crucible
furnace, and then cast in an iron mould at a temperature of
700-730.degree. C. to form an ingot. The ingot was subjected to
homogenization at 600.degree. C./20 h, water quenched, machined
into bars of .phi.80 mm, and then extruded into rods of .phi.10 mm
on 800T extruder, wherein the heating temperature of the ingot was
480.degree. C., the outlet temperature was about 520.degree. C.,
the ingot was directly cooled with water. The rods were extruded
into pipes of .PHI.8.times.0.4 mm on LJ300 type CONFORM continuous
extruder, the outlet temperature was about 450.degree. C., and then
the rods were directly cooled with water.
[0036] The properties of the pipes made of the alloy A-1 were
tested, wherein the melting point was determined by DSC
(Differential Scanning calorimetric), the tensile property was
determined in accordance with ISO 6892: 1998 (Room Temperature
Tensile Test of Metal Materials), the SWAAT corrosion resistance
test was conducted in accordance with ASTM/G85-1998 A3 of "Modified
Salt Mist Test Method" (sea water acidification recirculation
test), bulging was performed in accordance with EN ISO 8493
(bulging test method of metal material pipes), bending test was
conducted in accordance with ISO 8491-1998 (bending test of metal
material pipes (total cross section)), welding test was conducted
by welding 3003/4045 composite soldered aluminum alloy plates and
new alloy pipes. Detailed test results were shown in Table 2.
TABLE-US-00001 TABLE 1 Measured Chemical components of alloy A-1
(by weight %) Alloy Si Fe Mn Cu Cr Zn Zr Ti Design 0.2 <0.2 1.2
<0.03 0.15 <0.03 0.15 0.15 value Measured 0.19 0.10 1.15
0.001 0.15 0.0069 0.13 0.14 value
TABLE-US-00002 TABLE 2 Test results of properties of alloy A-1
Melting Tensile Property point strength Elongation SWAAT Bulging
ratio index (.degree. C.) (MPa) (%) (day) (45.degree. cone, %)
Measured 641.3 132 27.5 >30 >30 value
[0037] Additionally, the subsequent bending processed surface of
the pipes did not have tangerine hull thereon, and the pipes and
3003/4045 complex soldered aluminium alloy plates exhibit excellent
soldering properties.
Example 2
[0038] According to the alloy composition of the present invention,
99.7Al ingot and Si solvent, Al-10Mn, Al--SCr, Al-10Zr, Al-10Ti
intermediate alloys were used to make an alloy according to the
weight percent described as follows:
Al-0.9Mn-0.4Si-0.12Cr-0.15Zr-0.20Ti, which was named as alloy A-2
(the concrete composition of the alloy is shown in Table 3). The
alloy was melt and refined in a double 500 kg level flame furnaces,
and then machined into rods of .phi.12 mm by horizontal continuous
casting method, the casting temperature was 690-730.degree. C., and
then the rods were extruded into pipes of .PHI.8.times.0.4 mm on
C315 type CONFORM continuous extruder, the outlet temperature was
about 450.degree. C., and then the pipes were directly cooled with
water.
[0039] The properties of the pipes made of the alloy A-2 were
tested, wherein the melting point was determined by DSC
(Differential Scanning calorimetric), the tensile property was
determined in accordance with ISO 6892:1998 (Room Temperature
Tensile Test of Metal Materials), the SWAAT corrosion resistance
test was conducted in accordance with ASTM/G85-1998 A3 of "Modified
Salt Mist Test Method" (sea water acidification recirculation
test), bulging was performed in accordance with EN ISO 8493
(bulging test method of metal material pipes), bending test was
conducted in accordance with ISO 8491-1998 (bending test of metal
material pipes (total cross section)), welding test was conducted
by welding 3003/4045 composite soldered aluminum alloy plates and
new alloy pipes. Detailed test results were shown in Table 4.
TABLE-US-00003 TABLE 3 Tested chemical components of alloy A-2 (by
weight %) Alloy Si Fe Mn Cu Cr Zn Zr Ti Design 0.40 <0.2 0.9
<0.03 0.12 <0.03 0.15 0.20 value Mea- 0.363 0.171 0.863 0.008
0.094 0.023 0.146 0.168 sured value
TABLE-US-00004 TABLE 4 Test results of properties of alloy A-2
Melting Tensile Property point strength Elongation SWAAT Bulging
ratio index (.degree. C.) (MPa) (%) (day) (45.degree. cone, %)
Measured 650.0 113 33 >30 >30 value
[0040] Additionally, the subsequent bending processed surface of
the pipes did not have tangerine hull thereon, and the pipes and
3003/4045 complex soldered aluminium alloy plates exhibit excellent
soldering properties.
Example 3
[0041] Alloys A-Q within the compositions range of the present
inventive alloys were manufactured, and processed into pipes by the
method of Example 1. Detailed alloy compositions were shown in
Table 5.
TABLE-US-00005 TABLE 5 Tested chemical components of the inventive
alloys (by weight %) Alloys Si Fe Mn Cu Cr Zn Zr Ti A 0.120 0.164
0.971 0.007 0.102 0.017 0.135 0.158 B 0.598 0.171 0.963 0.008 0.094
0.023 0.146 0.168 C 0.801 0.156 0.927 0.008 0.092 0.019 0.125 0.171
D 1.183 0.171 0.906 0.006 0.094 0.023 0.137 0.168 E 0.319 0.166
0.327 0.006 0.091 0.011 0.129 0.169 F 0.321 0.170 0.691 0.007 0.098
0.017 0.131 0.178 G 0.334 0.159 0.927 0.005 0.101 0.010 0.134 0.167
H 0.327 0.161 1.211 0.009 0.097 0.009 0.127 0.174 I 0.610 0.169
1.069 0.008 0.059 0.012 0.141 0.176 J 0.606 0.158 1.096 0.007 0.218
0.014 0.132 0.179 K 0.368 0.156 0.932 0.007 0.101 0.013 0.056 0.164
L 0.343 0.160 0.916 0.007 0.098 0.018 0.187 0.176 M 0.399 0.161
0.971 0.005 0.108 0.010 0.129 0.087 N 0.391 0.157 0.961 0.007 0.099
0.008 0.124 0.273 P 0.126 0.158 0.311 0.008 0.052 0.009 0.058 0.087
Q 1.167 0.161 1.232 0.007 0.22 0.010 0.189 0.266 In the alloys A-D,
Si content was mainly changed. In the alloys E-H, Mn content was
mainly changed. In the alloys I-J, Cr content was mainly changed.
In the alloys K-L, Zr content was mainly changed. In the alloys
M-N, Ti content was mainly changed. The alloy P comprises a smaller
amount of alloying elements; the alloy Q comprises a greater amount
of alloying elements.
[0042] The properties of the pipes made of the alloys A-Q were
tested, wherein the melting point was determined by DSC
(Differential Scanning calorimetric), the tensile property was
determined in accordance with ISO 6892: 1998 (Room Temperature
Tensile Test of Metal Materials), the SWAAT corrosion resistance
test was conducted in accordance with ASTM/G85-1998 A3 of "Modified
Salt Mist Test Method" (sea water acidification recirculation
test), bulging was performed in accordance with EN ISO 8493
(bulging test method of metal material pipes), bending test was
conducted in accordance with ISO 8491-1998 (bending test of metal
material pipes (total cross section)), welding test was conducted
by welding 3003/4045 composite soldered aluminum alloy plates and
new alloy pipes. Detailed test results were shown in Table 6.
TABLE-US-00006 TABLE 6 Test results of properties of extruded pipes
of alloys A-Q DSC Tensile Elon- Property Melting strength gation
SWAAT Bulging ratio index point (.degree. C.) (MPa) (%) (day)
(45.degree. cone, %) A 650.8 114 33 >30 >30 B 649.1 116 32
>30 >30 C 648.8 119 32 >30 >30 D 643.3 117 32 >30
>30 E 649.2 92 38 >30 >30 F 648.9 107 34 >30 >30 G
649.6 116 32 >30 >30 H 646.2 123 30 >30 >30 I 644.8 121
30 >30 >30 J 643.9 126 29 >30 >30 K 648.0 113 33 >30
>30 L 649.8 117 32 >30 >30 M 647.2 112 33 >30 >30 N
649.8 118 32 >30 >30 P 650.6 89 38 >30 >30 Q 642.7 134
28 >30 >30
[0043] The results show:
[0044] The melting points of the inventive alloys were higher than
640.degree. C.;
[0045] the tensile strengths of the inventive alloy pipes were
89-134 Mpa;
[0046] the elongations of the inventive alloy pipes were
28-38%;
[0047] the Bulging ratio of the inventive alloy pipes were greater
than 30%;
[0048] tangerine hull disappeared on the subsequent bending
processed surface of the pipes;
[0049] pipe leakages were not occurred in the inventive alloy pipes
after they were corroded in SWAAT salt spray corrosion test for 30
days;
[0050] the inventive alloy pipes exhibit excellent soldering
properties when being soldered with 3003/4045 aluminium alloy
composite plates.
Comparative Example 1
[0051] In order to compare with the inventive alloy, pipes of
.PHI.8.times.0.4 mm were manufactured with 3003 alloy of the prior
art by the same manner of Example 2, and their properties were
tested by the same methods. The test results of the chemical
composition and properties of 3003 alloy were shown in Tables 7 and
8, respectively.
TABLE-US-00007 TABLE 7 Measured chemical components of 3003 alloy
(by weight %) Alloy Si Fe Mn Cu Cr Zn Zr Ti Measured 0.15 0.36 1.30
0.11 -- -- -- 0.03 value
TABLE-US-00008 TABLE 8 Test results of properties of 3003 aluminum
alloy pipes Melting Tensile Property point strength Elongation
SWAAT Bulging ratio index (.degree. C.) (MPa) (%) (day) (45.degree.
cone, %) Measured 646.1 125 26.2 <10 >30 value
[0052] Corrosion Test
[0053] Comparative test of SWAAT corrosion resistance was conducted
in accordance with ASTM/G85-1998 A3 of "Modified Salt Mist Test
Method" (sea water acidification recirculation test). FIG. 1 shows
the comparison of cross-section metallographic structure between
the pipes made of the inventive alloy A-2 and 3003 alloy after they
subjected to corrosion for 10 days. It can be seen from FIG. 1 that
after they underwent corrosion in 10 days, 3003 alloy pipes
produced obvious locally corroded deep cavity along outer wall,
whereas no corrosion evidences were found on the outer wall of the
pipes of inventive alloy A-2.
[0054] FIG. 2 shows the SEM (Scanning Electron Microscope) pictures
of the surfaces of the pipes made of the inventive alloy A-2 and
the 3003 alloy after they subjected to corrosion for 20 days, and
the left picture shows the inventive alloy, while the right picture
shows 3003 alloy. It can be seen from FIG. 2 that the outer surface
of 3003 alloy pipes produced obvious locally corroded deep cavity,
the corrosion exhibited quite non-uniform pitting corrosion;
whereas the outer surface of the pipes made of the inventive alloy
A-2 exhibited uniform corrosion without corrosion found appearing
local deep corroded cavity, there was even large area that keep
uncorroded. It was found by air pressure inspection that leakage
was found in the pipes of .PHI.8.times.0.4 mm made of 3003 alloy in
10 days, whereas leakage was not found in the pipes of
.PHI.8.times.0.4 mm made of the inventive alloy A-2 for more than
40 days.
[0055] Comparison of Hot Working Property
[0056] FIG. 3 shows true stress-strain curve of alloy rods obtained
on Gleeble 1500 thermal dynamic simulator by using the method of
cylindrical isothermal hot compression, deformation temperature was
300.degree. C. and 400.degree. C., respectively, and the straining
rate was 1 s.sup.-1 and 0.1 s.sup.-1, respectively. It can be seen
from the curve of FIG. 3 that the inventive alloy A-2 and 3003
alloy have same hot working property.
Comparative Example 2
[0057] In order to compare with the alloys of the present
invention, pipes of .PHI.8.times.0.4 mm were manufactured with 3026
alloy of the prior art by the same manner of Example 2, and their
properties were tested by the same methods. The test results of the
chemical composition and properties of 3026 alloy and the inventive
alloy A-2 were shown in Tables 9 and 10, respectively.
TABLE-US-00009 TABLE 9 Tested Chemical components of 3026 aluminum
alloy and the inventive alloy (by weight %) Alloy Si Fe Mn Cu Cr Zn
Zr Ti 3026 alloy 0.14 0.24 0.71 0.05 -- 0.157 -- 0.21 Inventive
alloy 0.363 0.171 0.863 0.008 0.094 0.023 0.146 0.168
TABLE-US-00010 TABLE 10 Test results of properties of the pipes
made of 3026 aluminum alloy and the inventive alloy Melting Tensile
Bulging Explosive Property point strength Elongation SWAAT ratio
pressure index (.degree. C.) (MPa) (%) (day) (45.degree. cone, %)
(MPa) 3026 alloy 657.4 91 39 >30 >30 16.5 Inventive alloy
650.0 113 33 >30 >30 18.1
[0058] The tensile property and elongation rate were determined in
accordance with ISO 6892: 1998 (Room Temperature Tensile Test of
Metal Materials); the SWAAT corrosion resistance test was conducted
in accordance with ASTM/G85-1998 A3 of "Modified Salt Mist Test
Method" (sea water acidification recirculation test); the Bulging
ratio was performed in accordance with EN ISO 8493 (bulging test
method of metal material pipes); the bending test was conducted in
accordance with ISO 8491-1998 (bending test of metal material pipes
(total cross section)), and the explosive pressure was tested using
pipes of D5.times.0.45 mm by "hydraulic pressure test method of
metal pipes" of GB/T241-2007.
[0059] It can be seen from above tables that the inventive alloy
products exhibit equivalent corrosion resistance as compared to the
3026 alloy products, but their explosive pressure was evidently
higher than the 3026 alloy products. The explosive pressure of the
new alloy products was higher than that of the 3026 alloy products
by 9.7%. The causes were: the adjustment of chemical components of
new alloys rendered that the tensile strength of the new alloy
products were higher than that of 3026 alloy, so that the safe
properties of the new alloy products were enhanced, and the
phenomenon of 3026 alloy is relative soft during machining was
solved.
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