U.S. patent application number 09/911468 was filed with the patent office on 2002-03-21 for aluminum brazing sheet.
This patent application is currently assigned to KOBE ALCOA TRANSPORTATION PRODUCTS LTD.. Invention is credited to Fukuda, Sunao, Isobe, Yasuaki, Nagaya, Takahiko, Okamoto, Tadashi, Takezoe, Osamu, Toyama, Taketoshi.
Application Number | 20020034653 09/911468 |
Document ID | / |
Family ID | 18722907 |
Filed Date | 2002-03-21 |
United States Patent
Application |
20020034653 |
Kind Code |
A1 |
Okamoto, Tadashi ; et
al. |
March 21, 2002 |
Aluminum brazing sheet
Abstract
A core material of an aluminum brazing sheet restricts Mg to
less than 0.3 wt. % and Fe to not more than 0.2 wt. %, and contains
more than 0.2 wt. % and not more than 1.0 wt. % of Cu, 0.3 to 1.3
wt. % of Si, 0.3 to 1.5 wt. % of Mn and the balance of Al and
inevitable impurities. A brazing filler material is formed on one
surface of the core material by Al-Si based aluminum alloy. Also, a
cladding material is formed on the other surface of the core
material, and contains less than 0.2 wt. % of Si, 2.0 to 3.5 wt. %
of Mg, not less than 0.5 wt. % and less than 2.0 wt. % of Zn and
the balance of Al and inevitable impurities. Further, the value
(cladding material hardness)/(the core material hardness) that is a
ratio of the hardness of the cladding material to the hardness of
the core material is not more than 1.5.
Inventors: |
Okamoto, Tadashi; (Moka-shi,
JP) ; Takezoe, Osamu; (Moka-shi, JP) ; Nagaya,
Takahiko; (Gifu-shi, JP) ; Isobe, Yasuaki;
(Nagoya-shi, JP) ; Toyama, Taketoshi; (Anjo-shi,
JP) ; Fukuda, Sunao; (Handa-shi, JP) |
Correspondence
Address: |
OBLON SPIVAK MCCLELLAND MAIER & NEUSTADT PC
FOURTH FLOOR
1755 JEFFERSON DAVIS HIGHWAY
ARLINGTON
VA
22202
US
|
Assignee: |
KOBE ALCOA TRANSPORTATION PRODUCTS
LTD.
Shinagawa-ku
JP
|
Family ID: |
18722907 |
Appl. No.: |
09/911468 |
Filed: |
July 25, 2001 |
Current U.S.
Class: |
428/654 |
Current CPC
Class: |
Y10S 428/933 20130101;
B23K 35/0238 20130101; F28F 21/084 20130101; B23K 35/286 20130101;
Y02P 70/50 20151101; B32B 15/016 20130101; C22C 21/00 20130101;
C22C 21/08 20130101; F28F 21/089 20130101; Y10T 428/12764 20150115;
F28F 2275/04 20130101; Y10T 29/49108 20150115 |
Class at
Publication: |
428/654 |
International
Class: |
B32B 015/20 |
Foreign Application Data
Date |
Code |
Application Number |
Jul 28, 2000 |
JP |
2000-229862 |
Claims
What is claimed is:
1. An aluminum brazing sheet comprising: a core material formed of
an aluminum alloy having a composition restricting Mg to less than
0.3 wt. % and Fe to not more than 0.2 wt. %, and containing more
than 0.2 wt. % and not more than 1.0 wt. % of Cu, 0.3 to 1.3 wt. %
of Si, 0.3 to 1.3 wt. % of Mn and the balance of Al and inevitable
impurities; a brazing filler material formed on one surface of the
core material by Al-Si based aluminum alloy; and a cladding
material formed on the other surface of said core material, said
cladding material being formed of an aluminum alloy containing less
than 0.2 wt. % of Si, 2.0 to 3.5 wt. % of Mg, not less than 0.5 wt.
% and less than 2.0 wt. % of Zn and the balance of Al and
inevitable impurities, wherein a ratio of the cladding material
hardness to the core material hardness is not more than 1.5.
2. The aluminum brazing sheet according to claim 1, wherein said
core material further contains not more than 0.3 wt. % of Cr.
3. The aluminum brazing sheet according to claim 1, wherein said
core material further contains not more than 0.3 wt. % of Zr.
4. The aluminum brazing sheet according to claim 2, wherein said
core material further contains not more than 0.3 wt. % of Zr.
5. The aluminum brazing sheet according to claim 1, wherein said
core material further contains not more than 0.3 wt. % of Ti.
6. The aluminum brazing sheet according to claim 2, wherein said
core material further contains not more than 0.3 wt. % of Ti.
7. The aluminum brazing sheet according to claim 3, wherein said
core material further contains not more than 0.3 wt. % of Ti.
8. The aluminum brazing sheet according to claim 4, wherein said
core material further contains not more than 0.3 wt. % of Ti.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Technical Filed of the Invention The present invention
relates to an aluminum brazing sheet used in a header, a side
plate, etc. of an automotive radiator, and more particularly, to an
aluminum brazing sheet for brazing which has high strength, high
formability and excellent brazing property.
[0002] 2. Description of the Related Art
[0003] Conventionally, as an aluminum brazing sheet for brazing
used in a header, a side plate, etc. of an automotive radiator,
Al-Mn based aluminum alloy of JIS3003 alloy, etc. as a core
material, Al-Si based aluminum alloy of JIS4045 and JIS4343 alloys,
etc. as a brazing filler material and Al-Zn based aluminum alloy as
a cladding material serving as a sacrificial anode have been used.
However, the brazing sheet comprising the core material composed of
Al-Mn alloy of JIS3003 alloy, etc. has strength of about 110 MPa
after the brazing so that the strength thereof is not sufficient
and corrosion resistance thereof is not sufficient. Although it is
effective that Mg is added to a core material in order to improve
the strength after the brazing, in a Nocolok Flux Brazing method,
the brazing property of a brazing sheet in which Mg is added to a
core material is significantly degraded so that it is not
preferable to add Mg to the core material.
[0004] Thus, as techniques to improve strength after the brazing
without degrading the brazing property, various proposals have been
made as described in Japanese Patent Laid-Open Nos. Hei 4-193926,
Hei 5-230577, Hei 6-145859 and Hei 6-212331, etc. Publications.
[0005] However, the prior arts described in the publications had a
problem that a further thinning of the brazing sheet cannot be
accomplished.
[0006] Since Si was added to a sacrificial anode cladding material
for high strength in the prior art disclosed in Japanese Patent
Laid-Open No. Hei 4-193926 Publication and Fe was not restricted in
Japanese Patent Laid-Open No. Hei 5-230577 Publication, formability
is low, and cracking tends to occur during pressing process of a
header.
[0007] Since much amount of Zn were added to a sacrificial anode
cladding material in Japanese Patent Laid-Open Nos. Hei 6-145859
and Hei 6-212331 Publications, formability is low, and cracking may
occur during pressing process of a header.
[0008] Further, since Mn was added to a sacrificial anode cladding
material for the high strength in the prior art disclosed in
Japanese Patent Laid-Open No. Hei 6-212331 Publication, formability
is low, and cracking tends to occur during pressing process of a
header.
[0009] As described above, it was difficult to obtain a brazing
sheet having all of features of strength after the brazing, brazing
property and formability in the prior arts.
[0010] However, in a heat exchanger such as an automotive radiator
and a heater core, there have been demands for thinning of material
to accomplish lightweight and manufacturing cost-down so that there
have been also strong demands for the thinning of aluminum brazing
sheet used in the brazing.
[0011] Further, the conventional high strength materials had a
problem that warping or spring back is generated in case of forming
or punching a plate material so that stable shape cannot be
maintained.
SUMMARY OF THE INVENTION
[0012] An object of the present invention is to provide an aluminum
brazing sheet having high strength after the brazing, excellent
brazing property and improved formability.
[0013] An aluminum brazing sheet according to the present invention
comprises a core material formed of an aluminum alloy having a
composition restricting Mg to less than 0.3 wt. % and Fe to not
more than 0.2 wt. %, and containing more than 0.2 wt. % and not
more than 1.0 wt. % of Cu, 0.3 to 1.3 wt. % of Si, 0.3 to 1.5 wt. %
of Mn and the balance of Al and inevitable impurities; a brazing
filler material formed on one surface of the core material by Al-Si
based aluminum alloy; and a cladding material formed on the other
surface of said core material. Said cladding material is formed of
an aluminum alloy containing less than 0.2 wt. % of Si, 2.0 to 3.5
wt. % of Mg, not less than 0.5 wt. % and less than 2.0 wt. % of Zn
and the balance of Al and inevitable impurities. The ratio of
(cladding material hardness)/(the core material hardness) that is a
ratio of the hardness of said cladding material to the hardness of
said core material is not more than 1.5.
[0014] Said core material may contain not more than 0.3 wt. % of
Cr, not more than 0.3 wt. % of Zr or not more than 0.3 wt. % of Ti.
The Mg content of said core material is preferably not more than
0.1 wt. %.
BRIEF DESCRIPTION OF THE DRAWINGS
[0015] The above objects, other objects, features and advantages of
the present invention will be better understood from the following
description taken in conjunction with the accompanying drawings, in
which:
[0016] FIG. 1 is a cross sectional view showing an aluminum brazing
sheet according to an example of the present invention; and
[0017] FIG. 2A is a perspective view showing a formed dimension of
a composite material formed in a box-shape, and FIG. 2B is a
diagram showing a method for measuring an amount of spring back in
the formed workpiece.
THE PREFERRED EMBODIMENTS OF THE INVENTION
[0018] The brazing sheet according to the present invention is
formed by laminating a cladding material on one surface of a core
material and a brazing filler material coated on the other surface
of the core material. Hereinafter, the reasons for the addition of
ingredients and composition limit of the core material, the
cladding material and the brazing filler material of the brazing
sheet material according to the present invention will be
described.
[0019] (a) Core material
[0020] Mg: less than 0.3 wt. %
[0021] Although Mg is extremely effective element for improving the
strength of the core material, if Mg is added not less than 0.3 wt.
%, the brazing property of the aluminum brazing sheet is degraded.
Particularly, in the brazing by Nocolok Flux Brazing method, the
degradation of brazing property by Mg is very significant. Thus,
the Mg content is limited to less than 0.3 wt. %. Preferably, the
Mg content is not more than 0.1 wt. % so as to further suppress the
degradation of brazing property.
[0022] Cu: more than 0.2 wt. % and not more than 1.0 wt. %
[0023] Cu is an element for improving the strength of the core
material and the corrosion resistance of the brazing filler
material. However, if Cu is added more than 1.0 wt. %, a melting
point of the core material is so reduced that workability during
brazing is degraded. Further, if the Cu content is not more than
0.2 wt. %, it is insufficient to improve the strength of the core
material. Thus, the Cu content is defined as from 0.2 to 1.0 wt. %.
Also, the Cu content is preferably not less than 0.3 wt. % in order
to raise the strength of the core material.
[0024] Si: from 0.3 to 1.3 wt. %
[0025] Si is an element for improving the strength of the core
material, and according to the addition of Si, an intermetallic
compound composed of Mg.sub.2Si is precipitated by reaction of
Al-Si-Mn based precipitate and Mg diffused from the cladding
material to improve the strength of the core material. However, if
the additive amount of Si is less than 0.3 wt. %, it is
insufficient to improve the strength of the core material,
meanwhile, if Si is added more than 1.3 wt. %, the melting point of
the core material is lowered, and workability during brazing
becomes degraded due to increase of a phase with lower melting
point. Thus, the Si content is defined as from 0.3 to 1.3 wt.
%.
[0026] Mn: from 0.3 to 1.5 wt. %
[0027] Mn is an element for enhancing the corrosion resistance and
the strength of the core material. If the additive amount of Mn is
less than 0.3 wt. %, it is impossible to sufficiently improve the
strength of the core material. Meanwhile, if the additive amount of
Mn is more than 1.5 wt. %, macro intermetallic compound is formed
so that processability and corrosion resistance are degraded. Thus,
the additive amount of Mn is defined as from 0.3 to 1.5 wt. %.
[0028] Fe: not more than 0.2 wt. %
[0029] Since Fe refines crystal grains, the brazing property is
degraded. Further, because Fe is diffused in the core material as
crystallization, workability(formability) is degraded. Thus, the
additive amount of Fe is defined as not more than 0.2 wt. %.
[0030] Cr: not more than 0.3 wt. %
[0031] Cr is an ingredient for enhancing the corrosion resistance,
the strength and the brazing property of the core material.
Although Cr is added more than 0.3 wt. %, further improvement for
the corrosion resistance, the strength and the brazing property
cannot be expected, and the processability and corrosion resistance
are degraded due to the formation of intermetallic compound. Thus,
in case of adding Cr, the additive amount thereof is defined as not
more than 0.3 wt. %.
[0032] Zr: not more than 0.3 wt. %
[0033] Zr is an element for improving the brazing property and the
corrosion resistance by making the grain coarse. Although Zr is
added more than 0.3 wt. %, further improvement for the brazing
property and the corrosion resistance cannot be expected, and
processability and corrosion resistance are degraded due to the
formation of intermetallic compound. Thus, in case of adding Zr,
the additive amount thereof is defined as not more than 0.3 wt.
%.
[0034] Ti: not more than 0.3 wt. %
[0035] Ti is an element for considerably improving the corrosion
resistance of the core material. Although Ti is added more than 0.3
wt. %, further improvement for the corrosion resistance cannot be
expected, and processability and corrosion resistance are degraded
due to the formation of intermetallic compound. Thus, in case of
adding Ti, the additive amount thereof is defined as not more than
0.3 wt. %.
[0036] (b) Cladding material
[0037] Si: less than 0.2 wt. %
[0038] Si improves the strength of the cladding material by
precipitating Mg.sub.2Si by reaction with Mg of the cladding
material serving as a sacrificial anode. However, because the
addition of Si degrades the formability of the cladding material,
the additive amount thereof is restricted to less than 0.2 wt.
%.
[0039] Mg: from 2.0 to 3.5 wt. %
[0040] Mg is an element for improving the strength and the
formability of the cladding material. By brazing heating, Mg added
to the cladding material is diffused into the cladding material and
combined with Si added to the cladding material to form Mg.sub.2Si,
thereby improving the strength after the brazing. If the additive
amount of Mg is less than 2.0 wt. %, improvement effect for the
strength is little, and formability is degraded. Meanwhile, if Mg
is added more than 3.5 wt. %, cladding compactibility is degraded
so that it becomes difficult to laminate the cladding material on
the core material. Thus, the additive amount of Mg is defined as
from 2.0 to 3.5 wt. %.
[0041] Zn: not less than 0.5 wt. % and less than 2.0 wt. %
[0042] Zn is an element for lowering the electric potential of the
cladding material serving as a sacrificial anode and improving the
corrosion resistance of inner face, and precipitates MgZn.sub.2 by
reaction with Mg of the sacrificial anode cladding material to
improve the strength. If the Zn content is less than 0.5 wt. %,
improvement effect for the strength is little, and the corrosion
resistance is degraded. Meanwhile, if Zn is added not less than 2.0
wt. %, the formability of the cladding material is degraded, which
is not preferable. Thus, the additive amount of Zn is defined as
not less than 0.5 wt. % and less than 2.0 wt. %.
[0043] The ratio of (cladding material hardness)/(core material
hardness) which is a ratio of the hardness of cladding material to
the hardness of core material: not more than 1.5
[0044] The hardness ratio of the cladding material to the core
material affects warping and spring back after the processing. If
the hardness ratio of the cladding material to the core material is
larger than 1.5, the cladding material has excessively high
strength comparing to the core material so that warping and spring
back are generated due to stress difference after the processing.
Therefore, (the cladding material hardness)/(the core material
hardness) value that is a ratio of the hardness of the cladding
material to the hardness of the core material is limited to not
more than 1.5.
[0045] The hardness ratio of the cladding material to the core
material is adjustable by properly setting the final annealing
condition. It is preferable that the final annealing temperature is
set to 330 to 550.degree. C., and then, a cooling to a room
temperature is performed at a cooling rate of about 2 to 20.degree.
C./hr. In case where the cooling rate exceeds 20.degree. C./hr, the
hardness of the cladding material becomes higher than that of the
core material so that the hardness ratio becomes not less than 1.5,
which is not preferable. Further, a temperature raising condition
during the annealing is not particularly limited.
(EXAMPLE)
[0046] Next, the properties of the examples according to the
invention will be described compared with those of comparative
examples beyond the claims.
[0047] First experimental test
[0048] Compositions of the core material used in the examples of
the present invention and the comparative examples are shown in
Table 1. In Table 1, the core material Nos. 1 to 10 are the
examples of the present invention, and the core material Nos. 11 to
15 are comparative examples beyond the scope of the present
invention. Further, in the core material Nos. 11 to 15, ingredients
beyond the compositions of the claims of the present invention are
shown with underlined.
[0049] In addition, the ingredient compositions of the cladding
material used in the examples and the comparative examples of the
present invention are shown in Table 2. In Table 2, the cladding
material Nos. 1 to 5 are the examples of the present invention, and
the cladding material Nos. 6 to 9 are the comparative examples
beyond the scope of the claims of the present invention. Further,
ingredients beyond the claims are shown with underlined.
1TABLE 1 Core Material Composition of Core Material (mass %) No. Si
Fe Cu Mn Mg Zn Cr Zr Ti Al Examples 1 0.4 0.05 0.5 1.1 0.00 0.00
0.00 0.00 0.00 bal. 2 0.8 0.05 0.5 1.1 0.00 0.00 0.00 0.00 0.00
bal. 3 1.0 0.05 0.5 1.1 0.00 0.00 0.00 0.00 0.00 bal. 4 0.8 0.05
0.3 1.1 0.00 0.00 0.00 0.00 0.00 bal. 5 0.8 0.05 0.7 1.1 0.00 0.00
0.00 0.00 0.00 bal. 6 0.8 0.05 0.5 0.4 0.00 0.00 0.00 0.00 0.00
bal. 7 0.8 0.05 0.5 1.1 0.1 0.00 0.00 0.00 0.00 bal. 8 0.8 0.05 0.5
1.1 0.00 0.00 0.1 0.00 0.00 bal. 9 0.8 0.05 0.5 1.1 0.00 0.00 0.1
0.1 0.00 bal. 10 0.8 0.05 0.3 1.1 0.00 0.00 0.1 0.1 0.15 bal.
comparative examples 11 0.2 0.05 0.5 1.1 0.00 0.00 0.00 0.00 0.00
bal. 12 0.8 0.05 0.15 1.1 0.00 0.00 0.00 0.00 0.00 bal. 13 0.8 0.4
0.5 1.1 0.00 0.00 0.00 0.00 0.00 bal. 14 0.8 0.05 0.5 0.2 0.00 0.00
0.1 0.00 0.00 bal. 15 0.8 0.05 0.5 1.1 0.3 0.00 0.1 0.1 0.00 bal.
Bal. means balance.
[0050]
2TABLE 2 Composition of the cladding material Cladding (mass %)
No.. Si Mg Zn Al Examples 1 0.02 2.1 1.5 bal. 2 0.15 2.1 1.5 bal. 3
0.02 3.0 1.5 bal. 4 0.02 2.1 0.7 bal. 5 0.02 2.1 1.2 bal.
Comparative example 6 0.3 2.1 1.5 bal. 7 0.02 1.5 1.5 bal. 8 0.02
2.1 0.2 bal. 9 0.02 2.1 2.5 bal.
[0051] By combining the core materials and the cladding materials
shown in Tables 1 and 2 and a brazing filler material (JIS 4045
alloy), an aluminum brazing sheet for brazing (aluminum alloy
composite material) as shown in FIG. 1 is manufactured. FIG. 1 is a
cross sectional view of the aluminum brazing sheet. As shown in
FIG. 1, an aluminum brazing sheet 4 is formed by laminating both
surfaces of a core material 1 with a cladding material 2 and a
brazing filler material 3. The following Tables 3 and 4 show a
construction of composite materials combined with the core
material, the cladding material and the brazing filler material.
The composite material Nos. 1 to 14 shown in Table 3 are the
examples of the present invention, and the composite material Nos.
15 to 23 shown in Table 4 are the comparative examples beyond the
scope of the present invention.
[0052] In the manufacturing process, the composite materials was
pressed up to 1 mm in thickness after a hot leveling rolling, and
maintained for 2 hours at a temperature of 400.degree. C. increased
at a heat rising rate of 40.degree. C./hr, and then cooled at a
cooling rate of 15.degree. C./hr. These obtained composite
materials were subjected to a test.
3TABLE 3 Brazing Total Composite Cladding filler thickness brazing
Core material material material Of brazing sheet Thickness
Thickness Thickness sheet No. No. (mm) No. (mm) (mm) (mm) Examples
1 1 0.8 1 0.1 0.1 1.0 2 2 0.8 1 0.1 0.1 1.0 3 3 0.8 1 0.1 0.1 1.0 4
4 0.8 1 0.1 0.1 1.0 5 5 0.8 1 0.1 0.1 1.0 6 6 0.8 1 0.1 0.1 1.0 7 7
0.8 1 0.1 0.1 1.0 8 8 0.8 1 0.1 0.1 1.0 9 9 0.8 1 0.1 0.1 1.0 10 10
0.8 1 0.1 0.1 1.0 11 2 0.8 2 0.1 0.1 1.0 12 2 0.8 3 0.1 0.1 1.0 13
2 0.8 4 0.1 0.1 1.0 14 2 0.8 5 0.1 0.1 1.0
[0053]
4TABLE 4 Brazing Total Composite Cladding filler thickness Mater-
Core material material material of brazing ial Thickness Thickness
Thickness sheet No. No. (mm) No. (mm) (mm) (mm) Compara- tive
examples 15 11 0.8 1 0.1 0.1 1.0 16 12 0.8 1 0.1 0.1 1.0 17 13 0.8
1 0.1 0.1 1.0 18 14 0.8 1 0.1 0.1 1.0 19 15 0.8 1 0.1 0.1 1.0 20 2
0.8 6 0.1 0.1 1.0 21 2 0.8 7 0.1 0.1 1.0 22 2 0.8 8 0.1 0.1 1.0 23
2 0.8 9 0.1 0.1 1.0
[0054] Also, the following tests were conducted on each of
composite materials composed of incorporation shown in Tables 3 and
4.
[0055] (a) Brazing test
[0056] Considering simplicity and quantization of estimation, the
brazing property was estimated by a flow coefficient according to
dropping test.
[0057] The brazing surface of each of composite materials was
coated with 5 g/m.sup.2 of Nocolok flux and dried, and then, heated
for five minutes at a temperature of 600.degree. C. under a
nitrogen atmosphere with not more than 200 weight ppm of oxygen
concentration and -40.degree. C. of a dew point temperature, and
the flow coefficient was measured.
[0058] The following Tables 5 and 6 show the estimative results of
the brazing property test. As shown in Tables 5 and 6, each example
according to the present invention has excellent brazing property,
but the composite material No. 19 of the comparative examples in
which 0.3 wt. % Mg is added to the core material had extremely low
brazing property compared with that of the present invention.
[0059] (b) Tension test
[0060] A composite material heated in the same manner as the
above-mentioned brazing test was left for 7 days at a room
temperature, and then, the tension test was conducted. The results
thereof are shown in Tables 5 and 6. All the examples of the
present invention had the high strength exceeding 160 MPa after the
brazing. Meanwhile, the composite material No. 15 of the
comparative examples in which Si of the core material is less than
the lower limit, the composite material No. 16 of the comparative
examples in which Cu of the core material is less than the lower
limit, and the composite material No. 18 of the comparative
examples in which Mn of the core material is less than the lower
limit had the low strength.
[0061] (c) Corrosion test on the cladding material
[0062] The corrosion test on the cladding material of a composite
material in the same manner as the above-mentioned brazing test was
conducted by using an artificial water (300 weight ppm Cl, 100
weight ppm SO.sub.4, and 5 weight ppm Cu). First, the composite
material was immerged into the artificial water of 88.degree. C.
for 8 hours, and then, at this state, left for 16 hours at a room
temperature with a heater turned off. The corrosion test in such
order was conducted for 30 days. The results thereof are shown in
Tables 5 and 6.
[0063] The corrosion on the cladding material of the examples
according to the present invention was stopped within the cladding
material so that excellent corrosion resistance was obtained, but
in the composite material No. 22 of the comparative examples in
which Zn of the cladding material is less than the lower limit, the
corrosion reaching to the core material occurred, thereby degrading
the corrosion resistance.
[0064] (d) Brazing corrosion test
[0065] A composite material heated in the same manner as the
above-mentioned brazing test was successively tested for 250 hours
by CASS. The results thereof are shown in Tables 5 and 6.
[0066] The examples according to the present invention had
excellent corrosion resistance in the brazing filler material,
while in the composite material No. 17 of the comparative examples
in which Fe of the core material exceeds the upper limit and the
composite material No. 19 of the comparative examples in which Mg
of the core material exceeds the upper limit, the corrosion
resistance was degraded.
[0067] (e) Formability
[0068] The formability of the composite material before brazing was
estimated by the Erichsen test and an angled cylinder drawing test.
All the examples according to the present invention had excellent
formability, but in the composite material No. 17 of the
comparative examples in which Fe of the core material exceeds the
upper limit and the composite material No. 20 of the comparative
examples in which Si of the cladding material exceeds the upper
limit, formability is significantly degraded, and in the composite
material No. 21 in which Mg of the cladding material is less than
the lower limit and the composite material No. 23 in which Zn of
the cladding material exceeds the upper limit, the reduction of
formability occurred.
5TABLE 5 Corrosion Corrosion depth in Formability Brazing Tensile
depth in the Cylinder property strength the brazing draw- Composite
(flow after cladding filler ing material coefficient) brazing
material material Erichsen test No. (%) MPa side (mm) side (mm)
(mm) mm Examples 1 70 165 0.06 0.16 10.7 10.8 2 70 172 0.06 0.16
10.6 10.7 3 70 178 0.06 0.16 10.6 10.7 4 70 162 0.06 0.16 10.6 10.6
5 70 182 0.06 0.16 10.6 10.7 6 70 160 0.06 0.16 10.7 10.8 7 67 182
0.06 0.17 10.6 10.7 8 70 175 0.06 0.13 10.6 10.7 9 72 174 0.06 0.13
10.6 10.7 10 72 174 0.06 0.16 10.6 10.7 11 70 175 0.06 0.16 10.6
10.7 12 70 184 0.06 0.16 10.7 10.8 13 70 168 0.06 0.16 10.8 10.9 14
70 170 0.06 0.16 10.7 10.8
[0069]
6TABLE 6 Corrosion Corrosion depth in Formability Brazing Tensile
depth in the Cylinder property strength the brazing draw- Composite
(flow after cladding filler ing material coefficient) brazing
material material Erichsen test No. (%) MPa side (mm) side (mm)
(mm) mm Compara- tive examples 15 70 158 0.06 0.16 10.6 10.7 16 70
154 0.06 0.16 10.6 10.7 17 70 174 0.06 0.20 10.0 10.2 18 70 155
0.06 0.16 10.7 10.8 19 30 202 0.06 0.25 10.6 10.7 20 70 174 0.06
0.16 10.1 10.2 21 70 165 0.06 0.16 10.3 10.4 22 70 165 0.18 0.16
10.8 10.9 23 70 174 0.06 0.16 10.3 10.4 Second experimental
test
[0070] Next, a second experimental test of the present invention
will be described. First, a composite materials having the
composition of the composite material No. 2 shown in Table 3 was
conducted with a cold rolling, and then, materials with the
hardness ratios of the cladding materials/the core materials as
shown in Table 7 were obtained through regulation of an annealing
condition. In addition, these hardness ratios were yielded in a
given cross section of the material by measuring micro Vickers
hardness at the center portions of the cladding material and core
material. This material was of 1.0 mm in thickness. FIG. 2A shows a
perspective view showing a formed dimension of a composite material
formed in a box-shape, and FIG. 2B is a diagram showing a method
for measuring an amount of spring back in the formed workpiece.
Furthermore, a unit of numerals shown in FIG. 2A is mm.
[0071] With using each material shown in Table 7, a cubical formed
part 10 was obtained by forming at predetermined conditions with a
mold in order that a cladding material face 2a becomes an inner
surface thereof and a brazing filler material face 3a becomes an
outer surface thereof. As shown in FIG. 2B, the formed part 10 was
placed on a platen 5, etc. with the brazing filler material face 3a
faced toward the platen, and the amount of spring back from the
normal processing at a spring back measuring portion A was
measured. The results are shown in Table 7.
[0072] In addition, in order to perform the assembling before
brazing, as shown in Table 7, it is better as the amount of spring
back are more little, and its allowable range is not more than 1.0
mm.
7TABLE 7 Composite Hardness ratio of brazing sheet cladding
material Amount of spring back No. to core material (mm) Example 24
0.8 0.1 25 1.0 0.2 26 1.3 0.6 27 1.5 1.0 Comparative example 28 1.7
1.5 29 2.0 2.0
[0073] As shown in Table 7, the amount of spring back of the
composite material Nos. 24 to 27 of the examples are not more than
1.0 mm and within the allowable range. Meanwhile, because the
hardness ratios of the cladding material and the core material of
the composite material Nos. 28 and 29 of the comparative examples
exceeded the upper limit of the present invention, the amount of
spring back exceeded the allowable range.
[0074] As described above, according to the present invention, the
aluminum brazing sheet composed of aluminum alloy composite
material having the high strength, the high corrosion resistance,
the high brazing property and the improved formability can be
obtained.
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