U.S. patent application number 14/762684 was filed with the patent office on 2015-12-17 for aluminum alloy clad material and heat exchanger that includes tube obtained by forming the clad material.
The applicant listed for this patent is UACJ CORPORATION. Invention is credited to Ryoko FUJIMURA, Tomohiro SHOJI, Hirokazu TANAKA, Toshikazu TANAKA, Naoki YAMASHITA.
Application Number | 20150361529 14/762684 |
Document ID | / |
Family ID | 51227443 |
Filed Date | 2015-12-17 |
United States Patent
Application |
20150361529 |
Kind Code |
A1 |
TANAKA; Toshikazu ; et
al. |
December 17, 2015 |
ALUMINUM ALLOY CLAD MATERIAL AND HEAT EXCHANGER THAT INCLUDES TUBE
OBTAINED BY FORMING THE CLAD MATERIAL
Abstract
An aluminum alloy clad material can produce a heat exchanger
tube that exhibits excellent outer-side corrosion resistance when
formed into a tube. The aluminum alloy clad material has a
three-layer structure in which one side of a core material is clad
with an inner cladding material, and the other side of the core
material is clad with a sacrificial anode material, the core
material being formed of an Al--Mn--Cu alloy that includes 0.6 to
2.0% of Mn and 0.03 to 1.0% of Cu, with the balance being aluminum
and unavoidable impurities, the inner cladding material being
formed of an Al--Mn--Cu alloy that includes 0.6 to 2.0% of Mn and
0.2 to 1.5% of Cu, with the balance being aluminum and unavoidable
impurities, the sacrificial anode material being formed of an
Al--Zn--Cu alloy that includes 0.5 to 6.0% of Zn and 0.03 to 0.3%
of Cu, with the balance being aluminum and unavoidable impurities,
and the relationship "Cu content (%) in sacrificial anode
material.ltoreq.Cu content (%) in core material.ltoreq.Cu content
(%) in inner cladding material" being satisfied. The aluminum alloy
clad material may have a two-layer structure that includes the core
material and the sacrificial anode material.
Inventors: |
TANAKA; Toshikazu;
(Chiyoda-ku, Tokyo, JP) ; SHOJI; Tomohiro;
(Chiyoda-ku, Tokyo, JP) ; FUJIMURA; Ryoko;
(Chiyoda-ku, Tokyo, JP) ; YAMASHITA; Naoki;
(Chiyoda-ku, Tokyo, JP) ; TANAKA; Hirokazu;
(Chiyoda-ku, Tokyo, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
UACJ CORPORATION |
Tokyo |
|
JP |
|
|
Family ID: |
51227443 |
Appl. No.: |
14/762684 |
Filed: |
January 17, 2014 |
PCT Filed: |
January 17, 2014 |
PCT NO: |
PCT/JP2014/050791 |
371 Date: |
July 22, 2015 |
Current U.S.
Class: |
165/134.1 ;
165/133; 204/196.15; 204/196.22 |
Current CPC
Class: |
B23K 35/0238 20130101;
C22C 21/02 20130101; F28F 19/06 20130101; F28F 21/089 20130101;
F28F 1/02 20130101; F28F 21/084 20130101; C23F 13/14 20130101; B23K
2101/14 20180801; C23F 13/18 20130101; F28F 2275/04 20130101; B23K
35/286 20130101; C22C 21/00 20130101; C22C 21/10 20130101; B32B
15/016 20130101; B23K 35/28 20130101; C22C 21/14 20130101 |
International
Class: |
C22C 21/10 20060101
C22C021/10; C22C 21/02 20060101 C22C021/02; F28F 19/06 20060101
F28F019/06; C23F 13/14 20060101 C23F013/14; C23F 13/18 20060101
C23F013/18; C22C 21/14 20060101 C22C021/14; C22C 21/00 20060101
C22C021/00 |
Foreign Application Data
Date |
Code |
Application Number |
Jan 23, 2013 |
JP |
2013-010116 |
Claims
1.-10. (canceled)
11. An aluminum alloy clad material comprising a core material and
a sacrificial anode material, one side of the core material being
clad with the sacrificial anode material, the core material being
formed of an Al--Mn--Cu alloy that comprises 0.6 to 2.0 mass % of
Mn and 0.03 to 1.0 mass % of Cu, with the balance being aluminum
and unavoidable impurities, the sacrificial anode material being
formed of an Al--Zn--Cu alloy that comprises 0.5 to 6.0 mass % of
Zn and 0.03 to 0.3 mass % of Cu, with the balance being aluminum
and unavoidable impurities, and a relationship of Cu content (mass
%) in sacrificial anode material.ltoreq.Cu content (mass %) in core
material being satisfied.
12. The aluminum alloy clad material according to claim 11, wherein
the core material further comprises one or more of 0.01 to 0.3 mass
% of Ti, 1.5 mass % or less of Si and 0.7 mass % or less of Fe.
13. The aluminum alloy clad material according to claim 11, wherein
the sacrificial anode material further comprises one or more of 1.5
mass % or less of Si, 0.7 mass % or less of Fe, and 1.5 mass % or
less of Mn.
14. The aluminum alloy clad material according to claim 12, wherein
the sacrificial anode material further comprises one or more of 1.5
mass % or less of Si, 0.7 mass % or less of Fe, and 1.5 mass % or
less of Mn.
15. An aluminum alloy clad material comprising a core material, an
inner cladding material, and a sacrificial anode material, one side
of the core material being clad with the inner cladding material,
the other side of the core material being clad with the sacrificial
anode material, the core material being formed of an Al--Mn--Cu
alloy that comprises 0.6 to 2.0 mass % of Mn and 0.03 to 1.0 mass %
of Cu, with the balance being aluminum and unavoidable impurities,
the inner cladding material being formed of an Al--Mn--Cu alloy
that comprises 0.6 to 2.0 mass % of Mn and 0.2 to 1.5 mass % of Cu,
with the balance being aluminum and unavoidable impurities, the
sacrificial anode material being formed of an Al--Zn--Cu alloy that
comprises 0.5 to 6.0 mass % of Zn and 0.03 to 0.3 mass % of Cu,
with the balance being aluminum and unavoidable impurities, and a
relationship of Cu content (mass %) in sacrificial anode
material.ltoreq.Cu content (mass %) in core material.ltoreq.Cu
content (mass %) in inner cladding material being satisfied.
16. The aluminum alloy clad material according to claim 15, wherein
the core material further comprises one or more of 0.01 to 0.3 mass
% of Ti, 1.5 mass % or less of Si and 0.7 mass % or less of Fe.
17. The aluminum alloy clad material according to claim 15, wherein
the inner cladding material further comprises one or more of 0.01
to 0.3 mass % of Ti, 1.5 mass % or less of Si and 0.7 mass % or
less of Fe.
18. The aluminum alloy clad material according to claim 16, wherein
the inner cladding material further comprises one or more of 0.01
to 0.3 mass % of Ti, 1.5 mass % or less of Si and 0.7 mass % or
less of Fe.
19. The aluminum alloy clad material according to claim 15, wherein
the sacrificial anode material further comprises one or more of 1.5
mass % or less of Si, 0.7 mass % or less of Fe, and 1.5 mass % or
less of Mn.
20. The aluminum alloy clad material according to claim 16, wherein
the sacrificial anode material further comprises one or more of 1.5
mass % or less of Si, 0.7 mass % or less of Fe, and 1.5 mass % or
less of Mn.
21. The aluminum alloy clad material according to claim 17, wherein
the sacrificial anode material further comprises one or more of 1.5
mass % or less of Si, 0.7 mass % or less of Fe, and 1.5 mass % or
less of Mn.
22. The aluminum alloy clad material according to claim 18, wherein
the sacrificial anode material further comprises one or more of 1.5
mass % or less of Si, 0.7 mass % or less of Fe, and 1.5 mass % or
less of Mn.
23. A heat exchanger produced by forming the aluminum alloy clad
material according to claim 11 into a tube so that the inner
cladding material defines a refrigerant passage, and the
sacrificial anode material comes in contact with the atmosphere,
assembling an aluminum fin with the tube, and brazing the aluminum
fin and the tube.
24. A heat exchanger produced by forming the aluminum alloy clad
material according to claim 13 into a tube so that the inner
cladding material defines a refrigerant passage, and the
sacrificial anode material comes in contact with the atmosphere,
assembling an aluminum fin with the tube, and brazing the aluminum
fin and the tube.
25. A heat exchanger produced by forming the aluminum alloy clad
material according to claim 14 into a tube so that the inner
cladding material defines a refrigerant passage, and the
sacrificial anode material comes in contact with the atmosphere,
assembling an aluminum fin with the tube, and brazing the aluminum
fin and the tube.
26. A heat exchanger produced by forming the aluminum alloy clad
material according to claim 15 into a tube so that the inner
cladding material defines a refrigerant passage, and the
sacrificial anode material comes in contact with the atmosphere,
assembling an aluminum fin with the tube, and brazing the aluminum
fin and the tube.
27. A heat exchanger produced by forming the aluminum alloy clad
material according to claim 21 into a tube so that the inner
cladding material defines a refrigerant passage, and the
sacrificial anode material comes in contact with the atmosphere,
assembling an aluminum fin with the tube, and brazing the aluminum
fin and the tube.
28. A heat exchanger produced by forming the aluminum alloy clad
material according to claim 22 into a tube so that the inner
cladding material defines a refrigerant passage, and the
sacrificial anode material comes in contact with the atmosphere,
assembling an aluminum fin with the tube, and brazing the aluminum
fin and the tube.
Description
TECHNICAL FIELD
[0001] The present invention relates to an aluminum alloy clad
material. More specifically, the invention relates to an aluminum
alloy clad material that can produce a heat exchanger tube that
exhibits excellent outer-side corrosion resistance when formed into
a tube. The invention also relates to a heat exchanger that
includes a tube obtained by forming the clad material.
BACKGROUND ART
[0002] An aluminum alloy extruded tube or a tube obtained by
bending an aluminum alloy sheet material has been used as a
refrigerant tube (refrigerant passage) for an aluminum heat
exchanger that is joined by brazing. Such a refrigerant tube is
designed so that a sacrificial anode effect due to a Zn diffusion
layer is achieved by thermally spraying Zn to the side of the
extruded tube that forms the outer side of the refrigerant tube, or
cladding the side of the tube (obtained by bending an aluminum
alloy sheet material) that forms the outer side of the refrigerant
tube with an Al--Zn-based alloy in order to improve the corrosion
resistance of the outer side (that comes in contact with the
atmosphere) of the refrigerant tube.
[0003] In recent years, a reduction in thickness and an improvement
in corrosion resistance have been required for materials used to
produce an automotive heat exchanger, and a decrease in corrosion
rate of the sacrificial anode layer through a reduction in Zn
content in the sacrificial anode material, and an increase in
thickness of the sacrificial anode layer have been desired.
However, it is difficult to reduce the amount of Zn thermally
sprayed to the extruded tube from the viewpoint of thermal spraying
efficiency. When using the tube obtained by bending an aluminum
alloy sheet material, since the potential of the sacrificial anode
material increases due to the effects of diffusion of Cu included
in the core material (Al--Mn--Cu-based alloy), and it is difficult
to achieve a potential difference sufficient to obtain the
sacrificial anode effect when the amount of Zn is reduced, it is
difficult to reduce the Zn content in the sacrificial anode
material. It is difficult to increase the thickness of the
sacrificial anode layer by increasing the cladding ratio from the
viewpoint of production cost.
[0004] A brazing sheet that is provided with a potential gradient
so that the potential increases from the outer side toward the
inner side after brazing by increasing the Cu content in the filler
metal situated on the inner side as compared with the core
material, a brazing sheet that is designed so that the potential
increases from outer side toward the inner side through a
concentration gradient of Zn and Cu that is formed by adding Zn to
the filler metal situated on the outer side, adding Cu to the
filler metal situated on the inner side, and adjusting the ratio of
Zn to Cu within a specific range, have been proposed. However,
since a layer that is formed by Cu diffused from the filler metal
and has a higher potential is thin, and the potential difference
between the layer having a higher potential and the core material
is small, most of the core material is consumed due to corrosion,
and the effect of suppressing occurrence of a through-hole is
insufficient immediately before a through-hole occurs.
RELATED-ART DOCUMENT
Patent Document
[0005] Patent Document 1: JP-A-2011-224656 [0006] Patent Document
2: JP-A-2009-127121 [0007] Patent Document 3: JP-A-2007-247021
SUMMARY OF THE INVENTION
Technical Problem
[0008] The inventors of the invention conducted experiments and
studies with regard to the effects of the configuration of an
aluminum alloy clad material that forms a tube obtained by bending
an aluminum alloy sheet material, and the alloy composition of each
layer of the clad material, on corrosion resistance. As a result,
the inventors found that, when the aluminum alloy clad material
that forms the tube has a two-layer structure that includes a core
material and a sacrificial anode material, or a three-layer
structure that includes a core material, a sacrificial anode
material, and an inner cladding material that is higher in
potential than the core material, one side of the core material
being clad with the sacrificial anode material, and the other side
of the core material being clad with the inner cladding material,
and the sacrificial anode material includes a small amount of Cu,
the corrosion rate of the sacrificial anode material is reduced so
that the sacrificial anode material remains for a long time,
occurrence of a through-hole can be suppressed, and the corrosion
resistance of the outer side (that comes in contact with the
atmosphere) is improved. When the aluminum alloy clad material has
the three-layer structure, the core material exhibits a sacrificial
anode effect on the inner cladding material, and the sacrificial
anode material and the core material function as a sacrificial
anode layer with respect to the inner cladding material (i.e., the
thickness of the sacrificial anode layer increases). In this case,
it is possible to suppress occurrence of a through-hole for a
longer time.
[0009] The invention was conceived as a result of conducting
further experiments and studies based on this finding. An object of
the invention is to provide an aluminum alloy clad material that
can produce a heat exchanger tube that exhibits excellent
outer-side corrosion resistance when formed into a tube, and a heat
exchanger that includes a tube obtained by forming the clad
material.
Solution to Problem
[0010] (1) According to one aspect of the invention, an aluminum
alloy clad material includes a core material and a sacrificial
anode material, one side of the core material being clad with the
sacrificial anode material, the core material being formed of an
Al--Mn--Cu alloy that includes 0.6 to 2.0% of Mn and 0.03 to 1.0%
of Cu, with the balance being aluminum and unavoidable impurities,
the sacrificial anode material being formed of an Al--Zn--Cu alloy
that includes 0.5 to 6.0% of Zn and 0.03 to 0.3% of Cu, with the
balance being aluminum and unavoidable impurities, and the
relationship "Cu content (%) in sacrificial anode
material.ltoreq.Cu content (%) in core material" being satisfied.
Note that the unit "%" used herein in connection with each alloy
component refers to "mass %". [0011] (2) In the aluminum alloy clad
material according to (1), the core material may further include
either or both of 1.5% or less of Si and 0.7% or less of Fe. [0012]
(3) In the aluminum alloy clad material according to (1) or (2),
the core material may further include 0.01 to 0.3% of Ti. [0013]
(4) According to another aspect of the invention, an aluminum alloy
clad material includes a core material, an inner cladding material,
and a sacrificial anode material, one side of the core material
being clad with the inner cladding material, the other side of the
core material being clad with the sacrificial anode material, the
core material being formed of an Al--Mn--Cu alloy that includes 0.6
to 2.0% of Mn and 0.03 to 1.0% of Cu, with the balance being
aluminum and unavoidable impurities, the inner cladding material
being formed of an Al--Mn--Cu alloy that includes 0.6 to 2.0% of Mn
and 0.2 to 1.5% of Cu, with the balance being aluminum and
unavoidable impurities, the sacrificial anode material being formed
of an Al--Zn--Cu alloy that includes 0.5 to 6.0% of Zn and 0.03 to
0.3% of Cu, with the balance being aluminum and unavoidable
impurities, and the relationship "Cu content (%) in sacrificial
anode material.ltoreq.Cu content (%) in core material.ltoreq.Cu
content (%) in inner cladding material" being satisfied. [0014] (5)
In the aluminum alloy clad material according to (4), the core
material may further include either or both of 1.5% or less of Si
and 0.7% or less of Fe. [0015] (6) In the aluminum alloy clad
material according to (4) or (5), the core material may further
include 0.01 to 0.3% of Ti. [0016] (7) In the aluminum alloy clad
material according to any one of (4) to (6), the inner cladding
material may further include either or both of 1.5% or less of Si
and 0.7% or less of Fe. [0017] (8) In the aluminum alloy clad
material according to any one of (4) to (7), the inner cladding
material may further include 0.01 to 0.3% of Ti. [0018] (9) In the
aluminum alloy clad material according to any one of (1) to (8),
the sacrificial anode material may further include one or two or
more of 1.5% or less of Si, 0.7% or less of Fe, and 1.5% or less of
Mn. [0019] (10) According to a further aspect of the invention, a
heat exchanger is produced by forming the aluminum alloy clad
material according to any one of (1) to (9) into a tube so that the
inner cladding material defines a refrigerant passage, and the
sacrificial anode material comes in contact with the atmosphere,
assembling an aluminum fin with the tube, and brazing the aluminum
fin and the tube.
Advantageous Effects of the Invention
[0020] The aspects of the invention thus provide an aluminum alloy
clad material that exhibits excellent outer-side corrosion
resistance when formed into a tube, and may suitably be used as a
material for forming a tube for a heat exchanger (particularly an
automotive heat exchanger), and a heat exchanger that includes a
tube obtained by forming the aluminum alloy clad material.
BRIEF DESCRIPTION OF DRAWINGS
[0021] FIG. 1 is a cross-sectional view illustrating an example of
a heat exchanger tube obtained by forming an aluminum alloy clad
material according to one embodiment of the invention.
[0022] FIG. 2 is a cross-sectional view illustrating another
example of a heat exchanger tube obtained by forming an aluminum
alloy clad material according to one embodiment of the
invention.
DESCRIPTION OF EMBODIMENTS
[0023] Aluminum alloy clad materials according to the embodiments
of the invention have a two-layer structure that includes a core
material and a sacrificial anode material, or a three-layer
structure that includes a core material, a sacrificial anode
material, and an inner cladding material that is higher in
potential than the core material, one side of the core material
being clad with the sacrificial anode material, and the other side
of the core material being clad with the inner cladding material,
wherein the sacrificial anode material includes Cu. When the
aluminum alloy clad material is formed into a tube so that the
inner cladding material defines a refrigerant passage, and the
sacrificial anode material comes in contact with the atmosphere,
and is assembled into a heat exchanger, the corrosion rate of the
sacrificial anode material is reduced, and the sacrificial anode
effect of the sacrificial anode material is maintained for a long
time. Therefore, it is possible to suppress occurrence of a
through-hole for a long time, and improve the corrosion resistance
of the outer side (that comes in contact with the atmosphere). When
the aluminum alloy clad material has the three-layer structure, the
core material exhibits a sacrificial anode effect on the inner
cladding material, and the sacrificial anode material and the core
material function as a sacrificial anode layer with respect to the
inner cladding material (i.e., the thickness of the sacrificial
anode layer increases). In this case, it is possible to suppress
occurrence of a through-hole for a longer time.
[0024] When the aluminum alloy clad material has the two-layer
structure, the core material is formed of an Al--Mn--Cu alloy that
includes 0.6 to 2.0% of Mn and 0.03 to 1.0% of Cu, with the balance
being aluminum and unavoidable impurities, and the sacrificial
anode material is formed of an Al--Zn--Cu alloy that includes 0.5
to 6.0% of Zn and 0.03 to 0.3% of Cu, with the balance being
aluminum and unavoidable impurities. Note that the relationship "Cu
content (%) in sacrificial anode material.ltoreq.Cu content (%) in
core material" is satisfied.
[0025] The core material may include either or both of 1.5% or less
of Si and 0.7% or less of Fe, and may include 0.01 to 0.3% of Ti.
The sacrificial anode material may include one or two or more of
1.5% or less of Si, 0.7% or less of Fe, and 1.5% or less of Mn.
[0026] When the aluminum alloy clad material has the three-layer
structure, the core material is formed of an Al--Mn--Cu alloy that
includes 0.6 to 2.0% of Mn and 0.03 to 1.0% of Cu, with the balance
being aluminum and unavoidable impurities, the inner cladding
material is formed of an Al--Mn--Cu alloy that includes 0.6 to 2.0%
of Mn and 0.2 to 1.5% of Cu, with the balance being aluminum and
unavoidable impurities, and the sacrificial anode material is
formed of an Al--Zn--Cu alloy that includes 0.5 to 6.0% of Zn and
0.03 to 0.3% of Cu, with the balance being aluminum and unavoidable
impurities. Note that the relationship "Cu content (%) in
sacrificial anode material.ltoreq.Cu content (%) in core
material.ltoreq.Cu content (%) in inner cladding material" is
satisfied.
[0027] The core material may include either or both of 1.5% or less
of Si and 0.7% or less of Fe, and may include 0.01 to 0.3% of Ti.
The inner cladding material may include either or both of 1.5% or
less of Si and 0.7% or less of Fe, and may include 0.01 to 0.3% of
Ti. The sacrificial anode material may include one or two or more
of 1.5% or less of Si, 0.7% or less of Fe, and 1.5% or less of
Mn.
[0028] The effects of each alloy component included in the core
material, the inner cladding material, and the sacrificial anode
material, and the reasons for which the content of each alloy
component is limited as described above, are described below.
Sacrificial Anode Material
Zn
[0029] Zn included in the sacrificial anode material increases the
potential of the sacrificial anode material. Zn is added to the
sacrificial anode material in order to adjust the balance in
potential with the core material and the inner cladding material.
The Zn content is preferably 0.5 to 6.0%. If the Zn content is less
than 0.5%, a sufficient effect may not be obtained. If the Zn
content exceeds 6.0%, the self-corrosion rate may increase, and the
corrosion-proof lifetime may decrease. The Zn content is more
preferably 1.0 to 5.0%.
Cu
[0030] Cu reduces the corrosion rate of the sacrificial anode
material. The Cu content is preferably 0.03 to 0.3%. If the Cu
content is less than 0.03%, the corrosion rate of the sacrificial
anode material may not be sufficiently reduced. If the Cu content
exceeds 0.3%, it may be difficult to obtain a sacrificial anode
effect due to an increase in potential. The Cu content is more
preferably 0.03 to 0.2%.
Si
[0031] Si improves the strength of the sacrificial anode material.
The Si content is preferably 1.5% or less. If the Si content
exceeds 1.5%, the self-corrosion rate may increase. The Si content
is more preferably 0.5% or less.
Fe
[0032] Fe improves the strength of the sacrificial anode material.
The Fe content is preferably 0.7% or less. If the Fe content
exceeds 0.7%, the self-corrosion rate may increase.
Mn
[0033] Mn improves the strength of the sacrificial anode material.
The Mn content is preferably 1.5% or less. If the Mn content
exceeds 1.5%, the self-corrosion rate may increase. The Mn content
is more preferably 0.5% or less. Note that the advantageous effects
of the invention are not impaired even when the sacrificial anode
material includes 0.3% or less of In, 0.3% or less of Sn, 0.3% or
less of Ti, 0.3% or less of V, 0.3% or less of Cr, 0.3% or less of
Zr, and 0.3% or less of B.
Core Material
Mn
[0034] Mn improves the strength of the core material. The Mn
content is preferably 0.6 to 2.0%. If the Mn content is less than
0.6%, a sufficient effect may not be obtained. If the Mn content
exceeds 2.0%, it may be difficult to roll the material. The Mn
content is more preferably 1.0 to 2.0%.
Cu
[0035] Cu increases the potential of the core material. Cu is added
to the core material in order to adjust the balance in potential
with the sacrificial anode material and the inner cladding
material. If the Cu content in the core material is lower than the
Cu content in the sacrificial anode material, it may be difficult
to provide a potential difference between the core material and the
sacrificial anode material. Therefore, it is preferable that the Cu
content in the core material be equal to or higher than the Cu
content in the sacrificial anode material. Cu included in the core
material is diffused into the sacrificial anode material during
brazing to reduce the potential difference between the core
material and the sacrificial anode material. Therefore, the Cu
content is preferably set to 1.5% or less. When the aluminum alloy
clad material has the three-layer structure, it may be difficult to
provide a potential difference between the core material and the
inner cladding material if the Cu content in the core material is
equal to or higher than the Cu content in the inner cladding
material. Therefore, it is preferable that the Cu content in the
core material be lower than the Cu content in the inner cladding
material. The Cu content is more preferably 0.6% or less.
Si
[0036] Si improves the strength of the core material. The Si
content is preferably 1.5% or less. If the Si content exceeds 1.5%,
the melting point of the core material may decrease, and the core
material may be easily melted during brazing. The Si content is
more preferably 0.8% or less.
Fe
[0037] Fe improves the strength of the core material. The Fe
content is preferably 0.7% or less. If the Fe content exceeds 0.7%,
the self-corrosion rate may increase.
Ti
[0038] Ti is separated into a high-concentration area and a
low-concentration area in the thickness direction of the core
material. These areas are distributed alternately in layers. Since
the low-concentration area is preferentially corroded as compared
with the high-concentration area, corrosion occurs in layers. This
prevents the progress of corrosion in the thickness direction, and
improves the corrosion resistance of the core material. The Ti
content is preferably 0.01 to 0.3%. If the Ti content is less than
0.01%, a sufficient effect may not be obtained. If the Ti content
exceeds 0.3%, a large crystallized product may be produced, and
formability may deteriorate. Note that the advantageous effects of
the invention are not impaired even when the core material includes
0.3% or less of V, 0.3% or less of Cr, 0.3% or less of Zr, and 0.3%
or less of B.
Inner Cladding Material
Mn
[0039] Mn improves the strength of the inner cladding material. The
Mn content is preferably 0.6 to 2.0%. If the Mn content is less
than 0.6%, a sufficient effect may not be obtained. If the Mn
content exceeds 2.0%, it may be difficult to roll the material. The
Mn content is more preferably 1.0 to 2.0%.
Si
[0040] Si improves the strength of the inner cladding material. The
Si content is preferably 1.5% or less. If the Si content exceeds
1.5%, the melting point of the inner cladding material may
decrease, and the inner cladding material may be easily melted
during brazing.
Fe
[0041] Fe improves the strength of the inner cladding material. The
Fe content is preferably 0.7% or less. If the Fe content exceeds
0.7%, the self-corrosion rate may increase.
Cu
[0042] Cu increases the potential of the inner cladding material.
Cu is added to the inner cladding material in order to adjust the
balance in potential with the core material. The Cu content is
preferably set to 0.2 to 1.5% so that the relationship "Cu content
(%) in core material.ltoreq.Cu content (%) in inner cladding
material" is satisfied. If the Cu content exceeds 1.5%, the melting
point of the inner cladding material may decrease, and the inner
cladding material may be easily melted during brazing. If the Cu
content in the inner cladding material is lower than the Cu content
in the core material, the core material may not function as a
sacrificial anode material with respect to the inner cladding
material, and the corrosion-proof lifetime may decrease. The Cu
content in the inner cladding material is more preferably 0.8% or
less.
Ti
[0043] Ti is separated into a high-concentration area and a
low-concentration area in the thickness direction of the inner
cladding material. These areas are distributed alternately in
layers. Since the low-concentration area is preferentially corroded
as compared with the high-concentration area, corrosion occurs in
layers. This prevents the progress of corrosion in the thickness
direction, and improves the corrosion resistance of the inner
cladding material. The Ti content is preferably 0.01 to 0.3%. If
the Ti content is less than 0.01%, a sufficient effect may not be
obtained. If the Ti content exceeds 0.3%, a large crystallized
product may be produced, and formability may deteriorate. Note that
the advantageous effects of the invention are not impaired even
when the inner cladding material includes 0.3% or less of V, 0.3%
or less of Cr, 0.3% or less of Zr, and 0.3% or less of B.
[0044] Note that it is undesirable to limit the Si content and the
Fe content in the sacrificial anode material, the core material,
and the inner cladding material to less than 0.03% since the
production cost increases when a high-purity ground metal is
used.
[0045] When the aluminum alloy clad material has the three-layer
structure, it is preferable to set the cladding ratio of the
sacrificial anode material to 5 to 30%, and set the cladding ratio
of the inner cladding material to 5 to 30%. If the cladding ratio
of the sacrificial anode material is less than 5%, the Zn
concentration in the sacrificial anode material may decrease due to
diffusion during brazing, and a sufficient sacrificial anode effect
may not be obtained. If the cladding ratio of the sacrificial anode
material exceeds 30%, it may be difficult to implement clad
rolling. The cladding ratio of the sacrificial anode material is
more preferably 10 to 30%. If the cladding ratio of the inner
cladding material is less than 5%, the Cu concentration in the
inner cladding material may decrease due to diffusion during
brazing, and the potential difference between the inner cladding
material and the core material may decrease, whereby it may be
difficult for the core material to exhibit a sacrificial anode
effect. If the cladding ratio of the inner cladding material
exceeds 30%, it may be difficult to implement clad rolling. The
cladding ratio of the inner cladding material is more preferably 10
to 30%.
[0046] A heat exchanger is produced by forming the aluminum alloy
clad material into a tube so that the inner cladding material
defines a refrigerant passage, and the sacrificial anode material
comes in contact with the atmosphere, assembling an aluminum fin
with the outer side (that comes in contact with the atmosphere) of
the tube, or the outer side and the inner side (that defines the
refrigerant passage) of the tube, and brazing the aluminum fin and
the tube.
[0047] As illustrated in FIG. 1, a tube material 1 may be produced
by forming an aluminum alloy clad material 2 into a tube, inserting
an inner fin 3 that is formed of a brazing sheet provided with a
filler metal on each side, and brazing a joint 4 of the tube
utilizing the filler metal provided to the inner fin 3. As
illustrated in FIG. 2, the tube material 1 may also be produced by
forming the aluminum alloy clad material 2 into a tube after
applying a filler metal paste 5 to the sacrificial anode material
of the aluminum alloy clad material 2 (or applying the filler metal
paste 5 to the sacrificial anode material of the aluminum alloy
clad material 2 after forming the aluminum alloy clad material 2
into a tube), and brazing the joint 4 utilizing the filler metal
paste 5.
[0048] When a heat exchanger is produced by forming the aluminum
alloy clad material into a tube so that the core material (when the
aluminum alloy clad material has the two-layer structure) or the
inner cladding material (when the aluminum alloy clad material has
the three-layer structure) defines a refrigerant passage, and the
sacrificial anode material comes in contact with the atmosphere
(i.e., is situated on the outer side), assembling an aluminum fin
with the tube, and brazing the aluminum fin and the tube at
600.degree. C. for 3 minutes, the sacrificial anode material, the
core material, and the inner cladding material included in the tube
satisfy the relationship "potential of sacrificial anode
material<potential of core material<potential of inner
cladding material", and the sacrificial anode material exhibits a
sacrificial anode effect on the core material. The sacrificial
anode material according to the embodiments of the invention that
is formed of the Al--Zn--Cu-based alloy shows a low corrosion rate
as compared with a sacrificial anode material that is formed of a
normal Al--Zn alloy, and exhibits a sacrificial anode effect for a
long time. Therefore, an improvement in corrosion resistance can be
achieved. When the aluminum alloy clad material has the three-layer
structure, the core material exhibits a sacrificial anode effect on
the inner cladding material, and the thickness of the sacrificial
anode layer increases. Since the inner cladding material that has a
higher potential remains even when most of the sacrificial anode
material and the core material have been consumed due to corrosion,
it is possible to suppress occurrence of a through-hole, and
improve the corrosion resistance of the outer side (that comes in
contact with the atmosphere).
EXAMPLES
[0049] The invention is further described below by way of examples
and comparative examples to demonstrate the advantageous effects of
the invention. Note that the following examples are for
illustration purposes only, and the invention is not limited to the
following examples.
Example 1
[0050] An ingot of a sacrificial anode material alloy (S1 to S11)
having the composition shown in Table 1, and ingots of a core
material alloy and an inner cladding material alloy (C1 to C20)
having the composition shown in Table 2, were cast using a
semi-continuous casting method. The ingot of the sacrificial anode
material alloy was homogenized at 500.degree. C. for 8 hours, and
hot-rolled (start temperature: 500.degree. C.) to a given
thickness. The ingot of the core material alloy was homogenized at
500.degree. C. for 8 hours, and machined. The ingot of the inner
cladding material alloy was homogenized at 500.degree. C. for 8
hours, and hot-rolled (start temperature: 500.degree. C.) to a
given thickness.
[0051] The hot-rolled sacrificial anode material alloy and the
hot-rolled inner cladding material alloy were then machined. The
aluminum alloys were stacked in the combination shown in Table 3,
hot-rolled (start temperature: 500.degree. C.) to a thickness of 3
mm, cold-rolled, subjected to process annealing at 400.degree. C.,
and then cold-rolled to obtain an aluminum alloy clad sheet
material (specimens No. 1 to No. 31) having a thickness of 0.2
mm.
Comparative Example 1
[0052] An ingot of a sacrificial anode material alloy (S12 to S18)
having the composition shown in Table 1, and ingots of a core
material alloy and an inner cladding material alloy (C21 to C26)
having the composition shown in Table 2, were cast using a
semi-continuous casting method. The ingot of the sacrificial anode
material alloy (S1), and the ingots of the core material alloy and
the inner cladding material alloy (C1 and C11) that were cast in
Example 1 were also used in Comparative Example 1. The ingot of the
sacrificial anode material alloy was homogenized at 500.degree. C.
for 8 hours, and hot-rolled (start temperature: 500.degree. C.) to
a given thickness. The ingot of the core material alloy was
homogenized at 500.degree. C. for 8 hours, and machined. The ingot
of the inner cladding material alloy was homogenized at 500.degree.
C. for 8 hours, and hot-rolled (start temperature: 500.degree. C.)
to a given thickness. In Tables 1 and 2, the values that fall
outside the scope of the invention are underlined.
[0053] The hot-rolled sacrificial anode material alloy and the
hot-rolled inner cladding material alloy were then machined. The
aluminum alloys were stacked in the combination shown in Table 4,
hot-rolled (start temperature: 500.degree. C.) to a thickness of 3
mm, cold-rolled, subjected to process annealing at 400.degree. C.,
and then cold-rolled to obtain an aluminum alloy clad sheet
material (specimens No. 101 to No. 114) having a thickness of 0.2
mm.
[0054] The resulting specimen was heated at 600.degree. C. for 3
minutes (equivalent to the brazing conditions), and subjected to
potential measurement, a tensile test, and a corrosion test as
described below. The results are shown in Tables 3 and 4.
Potential Measurement
[0055] The potential of the specimen was measured at room
temperature in a 5% NaCl aqueous solution of which the pH was
adjusted to 3 using acetic acid. The potential of the sacrificial
anode material was measured in a state in which the area other than
the surface of the sacrificial anode material was masked, and the
potential of the inner cladding material was measured in a state in
which the area other than the surface of the inner cladding
material was masked. When measuring the potential of the core
material, the specimen was ground from the sacrificial anode
material so that the center of the core material was exposed, and
the potential of the core material was measured in a state in which
the area other than the exposed core material was masked.
Tensile Test
[0056] A JIS-5 specimen was prepared using the resulting specimen,
and subjected to a tensile test in accordance with JIS Z 2241. A
case where the tensile strength of the specimen was 95 MPa or more
(equivalent to the strength of a 3003 alloy O-material) was
determined to be acceptable.
Corrosion Test
[0057] The specimen (that was masked so that the sacrificial anode
material was exposed) was subjected to a SWAAT test (ASTM G85) to
evaluate corrosion resistance. A specimen in which a through-hole
was not observed when 1000 hours had elapsed was evaluated as
"Good", a specimen in which a through-hole was not observed when
1500 hours had elapsed was evaluated as "Very good", and a specimen
in which a through-hole occurred before 1000 hours elapsed was
evaluated as "Bad".
TABLE-US-00001 TABLE 1 Component (mass %) No. Si Fe Cu Mn Zn Other
Al S1 0.1 0.3 0.1 0.0 2.5 Balance S2 0.1 0.2 0.3 0.0 0.6 Balance S3
0.1 0.3 0.1 0.0 1.2 Balance S4 0.1 0.2 0.03 0.0 5.0 Balance S5 0.1
0.2 0.1 0.0 6.0 Balance S6 0.4 0.1 0.1 0.0 2.0 Balance S7 0.2 0.5
0.1 0.0 2.0 Balance S8 0.1 0.1 0.1 0.5 2.5 Balance S9 1.2 0.0 0.3
0.2 3.8 Balance S10 0.2 0.2 0.1 0.0 2.0 Ti: 0.05, Cr: 0.05, Balance
V: 0.05, B: 0.05 S11 0.2 0.2 0.1 1.4 1.5 Sn: 0.01, In: 0.01 Balance
S12 2.0 0.1 0.1 0.2 3.0 Balance S13 0.4 1.0 0.1 0.4 4.5 Balance S14
0.3 0.4 0.02 0.2 3.5 Balance S15 0.4 0.4 0.4 0.1 2.0 Balance S16
0.4 0.3 0.1 2.0 5.0 Balance S17 0.5 0.4 0.1 0.5 0.1 Balance S18 0.3
0.2 0.1 0.2 8.0 Balance
TABLE-US-00002 TABLE 2 Component (mass %) No. Si Fe Cu Mn Other Al
C1 0.7 0.1 0.3 1.5 Balance C2 0.5 0.2 0.03 1.4 Balance C3 0.6 0.1
0.3 0.6 Balance C4 0.1 0.1 0.3 1.2 Balance C5 0.1 0.1 0.3 2.0
Balance C6 1.3 0.1 0.3 1.2 Balance C7 0.2 0.6 0.4 1.2 Balance C8
0.2 0.2 0.1 1.2 Ti: 0.2 Balance C9 0.7 0.2 0.3 1.2 Cr: 0.05, V:
0.05, B: 0.05 Balance C10 0.7 0.1 0.6 1.5 Balance C11 0.6 0.1 0.3
0.7 Balance C12 0.2 0.2 0.4 1.2 Balance C13 0.2 0.2 0.6 1.2 Balance
C14 0.2 0.2 1.0 1.2 Balance C15 0.2 0.2 0.4 2.0 Balance C16 1.3 0.2
0.2 1.0 Balance C17 0.2 0.2 1.4 1.2 Balance C18 0.7 0.2 0.8 1.2
Balance C19 0.2 0.5 0.3 1.2 Ti: 0.2 Balance C20 0.4 0.2 0.6 1.2 Cr:
0.05, V: 0.05, B: 0.05 Balance C21 2.0 0.3 0.3 1.2 Balance C22 0.5
1.0 0.2 1.3 Balance C23 0.4 0.4 0.1 0.3 Balance C24 0.9 0.3 2.0 1.2
Balance C25 0.4 0.5 1.2 2.5 Balance C26 0.3 0.4 0.02 1.4
Balance
TABLE-US-00003 TABLE 3 Specimen Potential (mV vs SCE) Sacrificial
anode material Core Inner cladding material Sacrificial Inner
Tensile Specimen Cladding material Cladding anode Core cladding
strength SWAAT No. No. ratio (%) No. No. ratio (%) material
material material (MPa) test 1 S1 10 C1 -- -- -780 -670 -- 140 Good
2 S1 20 C1 -- -- -830 -670 -- 135 Good 3 S2 20 C1 -- -- -710 -670
-- 145 Good 4 S3 20 C1 -- -- -750 -670 -- 140 Good 5 S4 20 C1 -- --
-875 -670 -- 135 Good 6 S5 20 C1 -- -- -880 -670 -- 140 Good 7 S6
20 C1 -- -- -810 -670 -- 140 Good 8 S7 20 C1 -- -- -810 -670 -- 130
Good 9 S8 20 C1 -- -- -820 -670 -- 130 Good 10 S9 20 C1 -- -- -810
-670 -- 145 Good 11 S10 20 C1 -- -- -820 -670 -- 130 Good 12 S11 20
C1 -- -- -880 -670 -- 135 Good 13 S4 20 C2 -- -- -875 -685 -- 120
Good 14 S1 20 C1 C7 20 -830 -670 -660 145 Very good 15 S1 10 C1 C7
20 -780 -670 -660 150 Very good 16 S1 20 C1 C7 10 -830 -670 -665
140 Very good 17 S1 20 C3 C11 20 -830 -680 -670 140 Very good 18 S1
20 C4 C12 20 -830 -675 -660 145 Very good 19 S1 20 C5 C13 20 -830
-665 -645 145 Very good 20 S1 20 C6 C14 20 -830 -660 -640 150 Very
good 21 S1 20 C7 C15 20 -830 -670 -665 145 Very good 22 S1 20 C8
C16 20 -830 -690 -670 140 Very good 23 S1 20 C9 C17 20 -830 -670
-610 155 Very good 24 S1 20 C1 C18 20 -830 -670 -645 145 Very good
25 S1 20 C1 C19 20 -830 -670 -670 140 Very good 26 S1 20 C1 C20 20
-830 -670 -650 145 Very good 27 S1 20 C10 C14 20 -830 -650 -640 160
Very good 28 S1 20 C11 C10 20 -830 -670 -650 150 Very good 29 S1 20
C12 C10 20 -830 -665 -650 150 Very good 30 S1 20 C13 C14 20 -830
-645 -640 160 Very good 31 S1 20 C14 C17 20 -830 -640 -610 175 Very
good
TABLE-US-00004 TABLE 4 Specimen Potential (mV vs SCE) Sacrificial
anode material Core Inner cladding material Sacrificial Inner
Tensile Specimen Cladding material Cladding anode Core cladding
strength SWAAT No. No. ratio (%) No. No. ratio (%) material
material material (MPa) test 101 S12 20 C1 -- -- -820 -670 -- 140
Bad 102 S13 20 C1 -- -- -850 -670 -- 135 Bad 103 S14 20 C1 -- --
-835 -670 -- 130 Bad 104 S15 20 C11 -- -- -790 -680 -- 145 Bad 105
S16 20 C1 -- -- -860 -670 -- 150 Bad 106 S17 20 C1 -- -- -680 -670
-- 140 Bad 107 S18 20 C1 -- -- -880 -670 -- 145 Bad 108 S1 20 C26
-- -- -780 -685 -- 120 Bad 109 S12 20 C1 C7 20 -820 -670 -660 145
Bad 110 S1 20 C21 C10 20 Core material melted 111 S1 20 C22 C10 20
-830 -680 -650 145 Bad 112 S1 20 C23 C10 20 -830 -685 -650 95 Good
113 S1 20 C1 C24 20 Inner cladding material melted 114 S1 20 C1 C25
20 Cracks occurred during rolling
[0058] As shown in Table 3, when subjecting specimens No. 1 to No.
31 according to the invention to the SWAAT test, a through-hole was
not observed when 1000 hours had elapsed. In particular, occurrence
of a through-hole was suppressed for a longer time when using
specimens No. 14 to No. 31 in which the inner cladding material was
provided. When a heat exchanger was produced by forming each of
these aluminum alloy clad materials into a tube so that the inner
cladding material defines a refrigerant passage, and the
sacrificial anode material comes in contact with the atmosphere
(situated on the outer side), assembling an aluminum fin with the
tube, and brazing the aluminum fin and the tube at 600.degree. C.
for 3 minutes, the outer side (that comes in contact with the
atmosphere) of the tube exhibited improved corrosion
resistance.
[0059] As shown in Table 4, the amount of self-corrosion of the
sacrificial anode material increased, and a through-hole occurred
during the SWAAT test when the Si content in the sacrificial anode
material was high (specimens No. 101 and No. 109), when the Fe
content in the sacrificial anode material was high (specimen No.
102), or when the Mn content in the sacrificial anode material was
high (specimen No. 105). The amount of self-corrosion of the
sacrificial anode material increased, and a through-hole occurred
during the SWAAT test when the Cu content in the sacrificial anode
material was low (specimen No. 103). The sacrificial anode effect
of the sacrificial anode material was insufficient, and a
through-hole occurred during the SWAAT test when the Cu content in
the sacrificial anode material was high (specimen No. 104), or when
the Zn content in the sacrificial anode material was low (specimen
No. 106). The amount of self-corrosion of the sacrificial anode
material increased, and a through-hole occurred during the SWAAT
test when the Zn content in the sacrificial anode material was high
(specimen No. 107). The sacrificial anode effect of the sacrificial
anode material was insufficient, and a through-hole occurred during
the SWAAT test when the Cu content in the core material was low
(specimen No. 108).
[0060] The core material was melted during brazing when the Si
content in the core material was high (specimen No. 110). The
amount of self-corrosion of the core material increased, and a
through-hole occurred during the SWAAT test when the Fe content in
the core material was high (specimen No. 111). Specimen No. 112
exhibited low tensile strength since the Mn content in the core
material was low.
[0061] The inner cladding material was melted during brazing when
the Cu content in the inner cladding material was high (specimen
No. 113). Cracks occurred during cold rolling when the Mn content
in the inner cladding material was high (specimen No. 114), and a
sound clad material could not be obtained.
REFERENCE SIGNS LIST
[0062] 1 Tube material [0063] 2 Aluminum alloy clad material [0064]
3 Inner fin [0065] 4 Joint [0066] 5 Filler metal paste
* * * * *