U.S. patent application number 10/934783 was filed with the patent office on 2005-03-31 for method for producing an aluminum alloy composite material for a heat exchanger, and aluminum alloy composite material.
Invention is credited to Doko, Takeyoshi, Tanaka, Satoshi, Yanagawa, Yutaka.
Application Number | 20050067066 10/934783 |
Document ID | / |
Family ID | 27800214 |
Filed Date | 2005-03-31 |
United States Patent
Application |
20050067066 |
Kind Code |
A1 |
Tanaka, Satoshi ; et
al. |
March 31, 2005 |
Method for producing an aluminum alloy composite material for a
heat exchanger, and aluminum alloy composite material
Abstract
A method for producing an aluminum alloy composite material for
a heat exchanger, which contains the steps of: homogenizing an
aluminum alloy core alloy by keeping at 530.degree. C. or more for
15 hours or more; fitting an Al--Si-series filler alloy on one side
or on both sides of the core alloy; hot rolling; cold rolling;
intermediate annealing, to completely recrystallize the core alloy;
and giving a strain of 1 to 10%, wherein the aluminum alloy core
alloy contains 0.01 to 1.0% by mass of Si, 0.1 to 2.0% by mass of
Fe, 0.1 to 2.0% by mass of Cu, 0.5 to 2.0% by mass of Mn, and less
than 0.2% by mass (including 0% by mass) of Ti, with the balance
being Al and inevitable impurities; and an aluminum alloy composite
material produced by the method.
Inventors: |
Tanaka, Satoshi; (Tokyo,
JP) ; Yanagawa, Yutaka; (Tokyo, JP) ; Doko,
Takeyoshi; (Tokyo, JP) |
Correspondence
Address: |
WESTERMAN, HATTORI, DANIELS & ADRIAN, LLP
1250 CONNECTICUT AVENUE, NW
SUITE 700
WASHINGTON
DC
20036
US
|
Family ID: |
27800214 |
Appl. No.: |
10/934783 |
Filed: |
September 7, 2004 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
10934783 |
Sep 7, 2004 |
|
|
|
PCT/JP03/02652 |
Mar 6, 2003 |
|
|
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Current U.S.
Class: |
148/535 |
Current CPC
Class: |
C22F 1/04 20130101; C22F
1/057 20130101; C22C 21/14 20130101; C22C 21/00 20130101; B32B
15/016 20130101 |
Class at
Publication: |
148/535 |
International
Class: |
C22F 001/04 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 8, 2002 |
JP |
2002-64398 |
Claims
1. A method for producing an aluminum alloy composite material for
a heat exchanger, comprising the steps of: homogenizing an aluminum
alloy core alloy by keeping the core alloy at 530C or more for 15
hours or more; fitting an Al--Si-series filler alloy on one side or
on both sides of the core alloy; hot rolling the resultant fitted
alloys; cold rolling the hot rolled fitted alloys; subjecting the
cold rolled fitted alloys to an intermediate annealing so as to
completely recrystallize the core alloy; and giving a strain of 1
to 10% to the resultant alloys, wherein the aluminum alloy core
alloy comprises 0.01 to 1.0% by mass (abbreviated to as %
hereinafter) of Si, 0.1 to 2.0% of Fe, 0.1 to 2.0% of Cu, 0.5 to
2.0% of Mn, and less than 0.2% (including 0%) of Ti, with the
balance being Al and inevitable impurities.
2. The method according to claim 1, wherein the homogenizing step
comprises keeping the core alloy at 530.degree. C. or more for 2
hours or more, followed by cooling, in which the core alloy is kept
for 1 hour or more at 500 to 560.degree. C. in the course of the
cooling, instead of keeping the core alloy at 530.degree. C. or
more for 15 hours or more.
3. The method according to claim 1 or 2, wherein the intermediate
annealing comprises keeping the cold rolled fitted alloys at 320 to
450.degree. C. for 1 hour or more.
4. The method according to claim 1 or 2, wherein the intermediate
annealing comprises: heating the cold rolled fitted alloys at a
heating speed of 30.degree. C./minute or more; keeping said fitted
alloys at 300 to 550.degree. C. for 1 to 180 seconds; and then
cooling the resultant alloys at a cooling speed of 30.degree.
C./minute or more.
5. The method according to claim 1 or 2, further comprising a step
of heat-treating after the step of giving the strain of 1 to
10%.
6. The method according to claim 5, wherein said heat-treating
after giving the strain of 1 to 10% comprises keeping at 200 to
380.degree. C. for 1 hour or more.
7. The method according to claim 5, wherein said heat-treating
after giving the strain of 1 to 10% comprises the steps of: heating
at a heating speed of 30.degree. C./minute or more; keeping at 250
to 420.degree. C. for 1 to 180 seconds; and then cooling at a
cooling speed of 30.degree. C./minute or more.
8. An aluminum alloy composite material for a heat exchanger, which
is produced by the method according to claim 1 or 2.
Description
TECHNICAL FIELD
[0001] The present invention relates to a method for producing an
aluminum alloy composite material for a heat exchanger. Further,
the present invention also relates to an aluminum alloy composite
material produced by the method.
BACKGROUND ART
[0002] In general, cores of heat exchangers, such as evaporators
and condensers, are manufactured, for example, as shown in FIG. 1,
by steps comprising: press-forming a composite material (brazing
sheet), which is made up from an aluminum alloy core alloy being
clad with a filler alloy on its both surfaces, to form corrugation;
stacking the corrugated two sheets of refrigerant passage-forming
members 1, to form refrigerant passageways 2 in the longitudinal
direction; and then brazing these sheets. In the figure, reference
numeral 3 denotes a corrugated fin; reference numeral 4 denotes a
brazed joint (flat portion), and reference numeral 5 denotes a
refrigerant passageway running in the vertical direction. Since the
sheet thickness of the material has been reduced in recent years,
to meet the need for lightweight materials, the aluminum member of
a heat exchanger for forming a refrigerant passageway 2 is strongly
required to be improved in mechanical strength, corrosion
resistance, and brazeability.
[0003] Heat for brazing induces diffusion of the filler alloy into
the aluminum alloy core alloy of the aluminum composite material
being used as a brazing sheet for forming the above refrigerator
passageway, in which the filler alloy penetrates into the core
alloy. Since diffusion of the filler alloy results in a decreased
amount of the filler alloy to be supplied to the portion to be
brazed, defective brazing, such as discontinuous brazing in a
brazed portion (defect owing to insufficient supply of filler
alloy) and decrease of pressure resistance of a heat exchanger, may
occur. In addition, the strength and corrosion resistance that the
core alloy inherently possesses are largely decreased at the
diffusion area of the filler alloy into the core alloy, and the
performance of the heat exchanger after heating for brazing is
considerably decreased.
[0004] To-suppress such diffusion of the filler alloy, there is a
method of applying a prestrain of 1 to 5% to a rolled material of
an Al--Mn-based alloy, to which an appropriate amount of Cu and Fe
are added, to permit the alloy to properly recrystallize by heating
in the brazing process. However, in this case, such a problem
arises as formability of the resulting alloy is decreased due to
work hardening caused by applying a strain, and cracks are occurred
in the forming process. Therefore, such countermeasures are far
from satisfactory.
DISCLOSURE OF THE INVENTION
[0005] The present invention resides in a method for producing an
aluminum alloy composite material for a heat exchanger, which
comprises the steps of: homogenizing an aluminum alloy core alloy
by keeping the core alloy at 530.degree. C. or more for 15 hours or
more; fitting an Al--Si-series filler alloy on one side or on both
sides of the core alloy; hot rolling the resultant fitted alloys;
cold rolling the hot rolled fitted alloys; subjecting the cold
rolled fitted alloys to an intermediate annealing so as to
completely recrystallize the core alloy; and giving a strain of 1
to 10% to the resultant alloys, wherein the aluminum alloy core
alloy comprises 0.01 to 1.0% by mass (abbreviated to as %
hereinafter) of Si, 0.1 to 2.0% of Fe, 0.1 to 2.0% of Cu, 0.5 to
2.0% of Mn, and less than 0.2% (including 0%) of Ti, with the
balance being Al and inevitable impurities.
[0006] Further, the present invention resides in an aluminum alloy
composite material for a heat exchanger, which is produced by the
above production method.
[0007] Other and further features and advantages of the present
invention will appear more fully from the following description,
taken in connection with the accompanying drawing.
BRIEF DESCRIPTION OF DRAWING
[0008] FIG. 1 is a partial perspective view for explaining an
automobile heat exchanger (radiator).
BEST MODE FOR CARRYING OUT THE INVENTION
[0009] According to the present invention, there is provided the
following means:
[0010] (1) A method for producing an aluminum alloy composite
material for a heat exchanger, comprising the steps of:
homogenizing an aluminum alloy core alloy by keeping the core alloy
at 530.degree. C. or more for 15 hours or more; fitting an
Al--Si-series filler alloy on one side or on both sides of the core
alloy; hot rolling the resultant fitted alloys; cold rolling the
hot rolled fitted alloys; subjecting the cold rolled fitted alloys
to an intermediate annealing so as to completely recrystallize the
core alloy; and giving a strain of 1 to 10% to the resultant
alloys, wherein the aluminum alloy core alloy comprises 0.01 to
1.0% by mass (abbreviated to as % hereinafter) of Si, 0.1 to 2.0%
of Fe, 0.1 to 2.0% of Cu, 0.5 to 2.0% of Mn, and less than 0.2%
(including 0%) of Ti, with the balance being Al and inevitable
impurities.
[0011] (2) The method according to item (1), wherein the
homogenizing step comprises keeping the core alloy at 530.degree.
C. or more for 2 hours or more; followed by cooling, in which the
core alloy is kept for 1 hour or more at 500 to 560.degree. C. in
the course of the cooling, instead of keeping the core alloy at
530.degree. C. or more for 15 hours or more.
[0012] (3) The method according to item (1) or (2), wherein the
intermediate annealing comprises keeping the cold rolled fitted
alloys at 320 to 450.degree. C. for 1 hour or more.
[0013] (4) The method according to item (1) or (2), wherein the
intermediate annealing comprises: heating the cold rolled fitted
alloys at a heating speed of 30.degree. C./minute or more; keeping
said fitted alloys at 300 to 550.degree. C. for 1 to 180 seconds;
and then cooling the resultant alloys at a cooling speed of
30.degree. C./minute or more.
[0014] (5) The method according to any one of items (1) to (4),
further comprising a step of heat-treating (final annealing) after
the step of giving the strain of 1 to 10%.
[0015] (6) The method according to item (5), wherein said
heat-treating after giving the strain of 1 to 10% comprises keeping
at 200 to 380.degree. C. for 1 hour or more.
[0016] (7) The method according to item (5), wherein said
heat-treating after giving the strain of 1 to 10% comprises the
steps of: heating at a heating speed of 30.degree. C./minute or
more; keeping at 250 to 420.degree. C. for 1 to 180 seconds; and
then cooling at a cooling speed of 30.degree. C./minute or
more.
[0017] (8) An aluminum alloy composite material for a heat
exchanger, which is produced by the method according to any one of
items (1) to (7).
[0018] The present invention is further described hereinafter.
[0019] The inventors have made intensive studies for developing a
material capable of preventing the filler alloy from penetrating
into the core alloy or the like while being excellent in
formability, and have obtained the following findings. The filler
alloy is suppressed from penetrating into the core alloy by
homogenizing a core alloy that is an Al--Mn-based alloy, to which a
proper amount of Cu and Fe are added, by giving a prestrain to the
material subjected to a rolling after fitting the filler alloy on
the core alloy, and by applying a predetermined heat treatment, if
necessary. The inventors have completed the present invention by
finding that formability can be improved while maintaining
corrosion resistance and strength by the treatments above.
[0020] The alloying elements which constitute the core alloy for
use in the present invention will be described first.
[0021] The content of Si is 0.01 to 1.0% by mass (abbreviated to as
% hereinafter), since Si suppresses the filler alloy from being
diffused while increasing the amount of the filler alloy to form
fillets, and has a function for enhancing the strength of the
material after brazing. The effect of Si is not exhibited at the
amount below the lower limit described above, and a melting
phenomenon called as burning may be caused at a brazing temperature
when the content of Si exceeds the upper limit described above. The
preferable content of Si is in the range from.0.1 to 0.6%.
[0022] Fe and Cu are effective for improving the strength and for
enhancing recrystallization. During heating for brazing, these
elements suppress the filler alloy from penetrating into a core
alloy, by completing the recrystallization before the filler alloy
starts penetration.
[0023] The content of Fe is limited in the range from 0.1 to 2.0%,
because the effect of Fe is not sufficiently manifested when the
content is less than the lower limit above, while corrosion
resistance decreases when the content exceeds the upper limit
above. The preferable range of the content of Fe is 0.1 to 1.1%,
more preferably 0.2 to 0.8%.
[0024] The content of Cu is limited in the range from 0.1 to 2.0%,
because the effect of Cu cannot be sufficiently manifested when the
content is below the lower limit above, while the base material
(matrix) may be melted when the content exceeds the upper limit
above. The preferable range of the content of Cu is from 0.1 to
1.1%, more preferably from 0.2 to 0.8%.
[0025] While Cu has an action of enhancing penetration of the
filler alloy, this action is suppressed by adding Fe together with
Cu.
[0026] Mn is responsible for improving the strength by forming a
solid solution with the aluminum matrix in the brazing step. The
content of Mn is limited in the range from 0.5 to 2.0% because the
effect of adding Mn is not sufficiently manifested when the content
is less than 0.5%, while rolling processibility and formability
decrease when the content exceeds 2.0%. Particularly preferable
range of the content of Mn is from 0.9 to 1.6%.
[0027] Ti is responsible for improving the corrosion resistance.
The content is limited to less than 0.2% (including 0%) because
recrystallization of the core alloy (aluminum alloy) is suppressed
in the brazing step when the content is 0.2% or more.
[0028] In the present invention, the balance of the core alloy
except the alloying elements described above is aluminum and
inevitable impurities. The kind and content of the inevitable
impurities are not particularly limited so long as they do not
inhibit the effect of the present invention.
[0029] Next, the reason for limiting the condition of the
homogenization treatment in the present invention will be
described.
[0030] Diffusion of the filler alloy into the core alloy occurring
by heating for brazing will advance along crystal grain boundaries
or pseudo-crystal grain boundaries in the core alloy when the
filler alloy is melted. When the brazing sheet is the material that
is completely annealed, the core alloy is not recrystallized by
heating for brazing. Therefore, the filler alloy is diffused along
the crystal grain boundaries in the core alloy. Accordingly, the
filler alloy will be more readily diffused as the crystal grains of
the core alloy are finer, and the degree of diffusion of the filler
alloy may be readily predicted.
[0031] On the other hand, when the core alloy is strained by
forming the brazing sheet, the core alloy will be partially
recrystallized by heating during the brazing step due to the
presence of the recrystallized grain boundaries or pseudo-crystal
grain boundaries. Since recrystallization behavior at this stage is
affected by the distribution of precipitates in the core alloy,
different distributions of the precipitates will bring various
states of diffusion of filler alloy, which causes variations in
characteristics such as the strength and corrosion resistance after
heating for brazing. Accordingly, it is effective to sufficiently
homogenize the core alloy and stabilize the distribution of the
precipitates in order to reduce the variation in states of
diffusion of the filler alloy.
[0032] Preferably, as the homogenization condition, the core alloy
is homogenized by keeping it at 530.degree. C. or more for 15 hours
or more, so as to stabilize the structure of the core alloy by
forming a solid solution of the precipitates formed in the cooling
process at casting. However, the upper limit of the homogenizing
temperature should be controlled within a range not melting the
core alloy. With respect to the lower limit of the homogenizing
time, a solid solution of the precipitates may not be sufficiently
formed when the homogenizing time is shorter than the time as
described above, which may be a cause of arising diffusion of the
filler alloy in the brazing step. While the upper limit of the
homogenizing time is not particularly limited so long as the
homogenizing time is controlled so as not to cause melting of the
core alloy, the time is preferably selected within an economically
acceptable range. The keeping time for the above homogenization
treatment is counted from the time when the temperature of the
aluminum alloy core alloy exceeds 530.degree. C. by heating to the
time when the temperature of the aluminum alloy core alloy is
lowered to 530.degree. C. or less by cooling.
[0033] Further for obtaining a material exhibiting less diffusion
of the filler alloy, the following homogenization treatment
conditions are effective. The core alloy is kept at 530.degree. C.
or more for 2 hours or more, preferably for 15 hours or more, and
more preferably the core alloy is kept at a temperature in the
range of from 570 to 620.degree. C. for 2 hours or more and then
subjected to a cooling step, during which the core alloy is kept at
a temperature in the range of from 500 to 560.degree. C. for 1 hour
or more. The precipitates in the core alloy are enhanced to form a
solid solution at 530.degree. C. or more, preferably at 570 to
620.degree. C., and precipitation is enhanced by keeping at 500 to
560.degree. C. during the cooling step. Thus the structure of the
core alloy is more stabilized and enables the filler alloy to be
suppressed from diffusing during heating for brazing.
[0034] Since the composite material of the present invention as a
material for a heat exchanger is required good formability before
brazing, the core alloy should be completely recrystallized in the
intermediate annealing step. Therefore, the intermediate annealing
condition is such that preferably keeping at 320 to 450.degree. C.
for 1 hour or more. When the annealing temperature is too low or
the annealing time is too short in the intermediate annealing step,
the core alloy may be insufficiently recrystallized. An annealing
temperature of exceeding 450.degree. C. is economically
disadvantageous and may allow crystal grains to grow into coarse
(giant) particles to decrease formability.
[0035] For further improving formability, the preferable
intermediate annealing condition is that the core alloy is heated
at a heating speed of 30 .degree. C./minute or more, kept at a
temperature in the range of from 300 to 550.degree. C. for 1 to 180
seconds, and then is cooled at a cooling speed of 30 .degree.
C./minute or more. This process enables the formability to be
ensured, since the recrystallized grain size of the aluminum alloy
material for the core alloy becomes more uniform and finer. It is
not preferable that either the heating speed or the cooling speed
is too slow, the keeping temperature is too high, or the keeping
time is too long, since the crystal grains of the aluminum alloy
material become too coarse. Keeping the temperature too low or
keeping the time too short is also not preferable since
recrystallization during the annealing process becomes
insufficient.
[0036] When a brazing sheet that is composed of a completely
recrystallized core alloy is subjected to forming, unstable
diffusion of the filler alloy arises at a portion being given a
specific degree of work strain. It was confirmed that the amount of
strain causing the above-stated diffusion of the filler alloy is in
the range of from 0 to less than 1%, in the case of the core alloy
composed of the Al--Mn-based alloy. On the other hand, heating the
core alloy having an amount of strain of 1% or more for brazing
does not result in diffusion of the filler alloy during the brazing
process, since the recrystallization of the core alloy is completed
in a low temperature region before the filler alloy is melted.
Accordingly, a composite material exhibiting a small degree of
diffusion in the later processes of forming and heating for brazing
may be obtained by giving beforehand the brazing sheet a work
prestrain of 1% or more that is larger than the amount of strain
causing diffusion of the filler alloy in a brazing sheet. Diffusion
occurs at a portion having a low degree of work strain when the
given strain is less than 1%. On the other hand, given strain of
exceeding 10% is not preferable, since formability of the material
decreases.
[0037] Besides, among heat exchangers, some are severely required
to have excellent formability, as is the plate material for an
evaporator. In order to comply with such usage, a heat treatment
(final annealing) may be applied, if necessary, after giving the
strain as described above. Heat treatment after giving a strain is
not necessarily required particularly when a given strain is 1 to
3%. However, when no heat treatment is applied after giving a
strain, it is preferable in the intermediate annealing step to heat
at a heating speed of 30 .degree. C./minute or more and to cool at
a cooling speed of 30.degree. C./minute or more after keeping a
temperature of 300 to 550.degree. C. for 1 to 180 seconds. On the
other hand, when the given strain is 3 to 10%, it is particularly
preferable to apply a heat treatment after giving a strain.
[0038] Regarding a specific heat-treatment condition after giving a
strain, a heat-treatment that a brazing sheet is heat-treated at
200 to 380.degree. C. by keeping the temperature for 1 hour or
more, or a heat-treatment that a brazing sheet is heated at a
heating speed of 30.degree. C./minute or more, kept at a
temperature of 250 to 420.degree. C. for 1 to 180 seconds and then
cooled at a cooling speed of 30.degree. C./minute or more, or the
like, is preferable for improving the performance of formability.
Improvement of formability may not be remarkable under a
heat-treatment condition out of the range as described above.
[0039] Kinds of filler alloys for use in the present invention are
not particularly limited as far as Al--Si-series filler alloys are
used. Various kinds of known filler alloys, for example, such as an
alloy JIS 4045, may be used. No limitations are imposed on the
cladding method of the core alloy with the filler alloy, such as a
cladding atmosphere and a clad ratio. Usual methods may be
appropriately used within a range not impairing the effect of the
present invention.
[0040] No limitations are also imposed on hot rolling and cold
rolling (for example, reduction percentage) in the present
invention, so long as a prescribed thickness is attained in each
production step, and usual methods may be appropriately
applied.
[0041] The aluminum alloy composite material produced by the method
of the present invention may be used for header plates and tanks,
as well as for refrigerant passageway tubes of heat exchangers such
as evaporators and radiators. Besides, the composite material of
the present invention may also be used for heater tubes and
condenser tubes or the like, and further may be used for any
members, if the sheet thickness is preferably 0.6 mm or less, as
the composite material to which the present invention is
applicable.
[0042] The aluminum alloy composite material of the present
invention for use in heat exchangers may be used as brazing
materials for braze-bonded products, to prevent the filler alloy
from penetrating into the core alloy or the like, while having good
formability. Further, the production method of the present
invention is a preferable method for producing the aluminum alloy
composite material for heat exchangers.
[0043] The aluminum alloy composite material produced by the
production method of the present invention has excellent corrosion
resistance and high strength with a small degree of diffusion of
the filler alloy at any degree of forming. The material is also
ready for forming since decrease of formability by giving a strain
may be prevented by controlling the heat-treatment condition.
[0044] Accordingly, the present invention is able to exert
remarkable industrial effects such as ensuring of long term
reliability when being applied to heat exchanger materials.
EXAMPLE
[0045] The present invention is described in more detail
hereinafter with reference to examples and comparative examples,
however the present invention is by no means limited to these
examples.
[0046] An aluminum alloy for a core alloy having a composition of
0.25% of Si, 0.5% of Fe, 0.15% of Cu and 1.1% of Mn with the
balance being Al, and JIS 4045 alloy for a filler alloy were cast
using a casting mold, respectively. The core alloy was homogenized
under a condition with a temperature and a keeping time as shown in
Table 1, and was finished to a thickness of 40 mm by scalping.
Regarding the filler alloy, the ingot was machined by scalping, hot
rolled, and was fitted to both sides of the core alloy with a clad
ratio of 10% on each side. The resultant fitted alloys were heated
to 500.degree. C., hot-rolled to a thickness of 3.5 mm, and cold
rolled to form a triple layer clad material with a thickness of 0.5
mm.
[0047] The cold rolled alloys above were subjected to intermediate
annealing as shown in Table 1 to prepare tempered O-materials. The
core alloy was completely recrystallized by this intermediate
annealing. Prestrained materials were produced by giving strains
with the reduction percentage shown in Table 1 using a tension
leveler. As shown in Table 1, prestrained materials were subjected
to or not subjected to a heat treatment (final annealing) after
giving the strain.
[0048] First, for evaluating formability of each of the composite
materials, an Erichsen test was conducted and the height (fracture
height (mm)) at generating cracks in the samples was measured. A
refrigerant flow passageway 1 as shown in FIG. 1 was formed by
forming (degree of forming of 0 to 15%) to test formability. The
results are also listed in Table 1.
[0049] One formed sheet having a shape of a refrigerant flow
passageway was placed on another formed sheet having the same shape
and these sheets were brazed by heating, and thus refrigerant flow
passageway tubes having the refrigerant flow passageways as shown
by reference numeral 2 in FIG. 1 were produced. The sheets were
brazed under the condition of heating at 600.degree. C. for 5
minutes in an inert gas atmosphere after being coated with a
fluoride based flux. State of diffusion of the filler alloy
(penetration of the filler alloy) was observed on the cross section
of the refrigerant flow passageway tube. Furthermore, corrosion
test of the refrigerant flow passageway tube was conducted and the
depth of corrosion pits (.mu.m) were measured after the corrosion
test. A cycle of spraying 5% aqueous NaCl solution for 4 hours
(40.degree. C., 98% RH) drying for 4 hours (55.degree. C., 30% RH)
damping for 4 hours (50.degree. C., 98% RH) was repeatedly applied
for 1 month in the corrosion test. The results are also shown in
Table 1.
1 TABLE 1 Homogenization conditions Cooling conditions with
resetting: Intermediate annealing Final Keeping 540.degree. C.
.times. 2 h Final temperature time without resetting: Heating
temperature Keeping Cooling (.degree. C.) (hr) Slow cooling speed
(.degree. C.) time speed Example 1 600 16 with resetting 80.degree.
C./min 480 10 sec 80.degree. C./min Example 2 600 16 with resetting
80.degree. C./min 480 10 sec 80.degree. C./min Example 3 540 18
Slow cooling 40.degree. C./hr 250 4 hr 40.degree. C./hr Example 4
540 18 Slow cooling 40.degree. C./hr 250 4 hr 40.degree. C./hr
Example 5 540 18 Slow cooling 40.degree. C./hr 250 4 hr 40.degree.
C./hr Example 6 540 18 Slow cooling 40.degree. C./hr 250 4 hr
40.degree. C./hr Example 7 540 18 Slow cooling 40.degree. C./hr 250
4 hr 40.degree. C./hr Example 8 540 18 Slow cooling 40.degree.
C./hr 250 4 hr 40.degree. C./hr Example 9 540 18 Slow cooling
80.degree. C./min 480 10 sec 80.degree. C./min Example 10 540 18
Slow cooling 80.degree. C./min 480 10 sec 80.degree. C./min Example
11 540 18 Slow cooling 80.degree. C./min 480 10 sec 80.degree.
C./min Example 12 540 18 Slow cooling 80.degree. C./min 480 10 sec
80.degree. C./min Example 13 540 18 Slow cooling 80.degree. C./min
480 10 sec 80.degree. C./min Example 14 540 18 Slow cooling
80.degree. C./min 480 10 sec 80.degree. C./min Example 15 540 18
Slow cooling 80.degree. C./min 480 10 sec 80.degree. C./min Example
16 600 16 with resetting 80.degree. C./min 480 10 sec 80.degree.
C./min Example 17 600 16 with resetting 80.degree. C./min 480 10
sec 80.degree. C./min Example 18 600 16 with resetting 80.degree.
C./min 480 10 sec 80.degree. C./min Example 19 600 16 with
resetting 80.degree. C./min 480 10 sec 80.degree. C./min Example 20
600 16 with resetting 80.degree. C./min 480 10 sec 80.degree.
C./min Example 21 600 16 with resetting 80.degree. C./min 480 10
sec 80.degree. C./min Example 22 600 16 with resetting 80.degree.
C./min 480 10 sec 80.degree. C./min Example 23 600 16 with
resetting 40.degree. C./hr 380 2 hr 40.degree. C./hr Example 24 600
16 with resetting 40.degree. C./hr 380 2 hr 40.degree. C./hr
Example 25 600 16 with resetting 40.degree. C./hr 380 2 hr
40.degree. C./hr Example 26 600 16 with resetting 40.degree. C./hr
380 2 hr 40.degree. C./hr Example 27 600 3 with resetting
40.degree. C./hr 380 2 hr 40.degree. C./hr Example 28 600 3 with
resetting 80.degree. C./min 480 10 sec 80.degree. C./min
Comparative 520 14 Slow cooling 120.degree. C./hr 400 2 hr
120.degree. C./hr example 1 Comparative 600 8 Slow cooling
120.degree. C./hr 400 2 hr 120.degree. C./hr example 2 Comparative
600 3 Slow cooling 40.degree. C./hr 380 2 hr 40.degree. C./hr
example 3 Comparative 600 16 Slow cooling 80.degree. C./min 480 10
sec 80.degree. C./min example 4 Comparative 600 16 Slow cooling
40.degree. C./hr 380 2 hr 40.degree. C./hr example 5 Amount Depth
of Erichsen of Final annealing conditions corrosion pit test pre-
Final Penetration after fracture strain Heating temperature Keeping
Cooling of filler corrosion test height (%) speed (.degree. C.)
time speed alloy (.mu.m) (mm) Formability Example 1 2.0 Without
final annealing .circleincircle. 64 8.8 .largecircle. Example 2 3.0
Without final annealing .circleincircle. 61 8.6 .largecircle.
Example 3 2.0 80.degree. C./min 350 10 sec 80.degree. C./min
.largecircle. 70 9.1 .circleincircle. Example 4 4.0 80.degree.
C./min 350 10 sec 80.degree. C./min .largecircle. 68 9.0
.circleincircle. Example 5 8.0 80.degree. C./min 350 10 sec
80.degree. C./min .largecircle. 71 9.1 .circleincircle. Example 6
2.0 40.degree. C./hr 250 4 hr 40.degree. C./hr .largecircle. 71 9.0
.circleincircle. Example 7 4.0 40.degree. C./hr 250 4 hr 40.degree.
C./hr .largecircle. 70 9.1 .circleincircle. Example 8 8.0
40.degree. C./hr 250 4 hr 40.degree. C./hr .largecircle. 70 9.1
.circleincircle. Example 9 2.0 40.degree. C./hr 250 4 hr 40.degree.
C./hr .largecircle. 70 9.7 .circleincircle. Example 10 2.0
80.degree. C./min 350 10 sec 80.degree. C./min .largecircle. 74 9.4
.circleincircle. Example 11 4.0 40.degree. C./hr 250 4 hr
40.degree. C./hr .largecircle. 65 9.6 .circleincircle. Example 12
4.0 40.degree. C./hr 300 2 hr 40.degree. C./hr .largecircle. 69 9.4
.circleincircle. Example 13 4.0 80.degree. C./min 350 10 sec
80.degree. C./min .largecircle. 67 9.3 .circleincircle. Example 14
8.0 40.degree. C./hr 250 4 hr 40.degree. C./hr .largecircle. 64 9.2
.circleincircle. Example 15 8.0 80.degree. C./min 350 10 sec
80.degree. C./min .largecircle. 65 9.0 .circleincircle. Example 16
2.0 40.degree. C./hr 250 4 hr 40.degree. C./hr .circleincircle. 61
9.9 .circleincircle. Example 17 2.0 80.degree. C./min 350 10 sec
80.degree. C./min .circleincircle. 65 9.7 .circleincircle. Example
18 4.0 40.degree. C./hr 250 4 hr 40.degree. C./hr .circleincircle.
52 9.7 .circleincircle. Example 19 4.0 40.degree. C./hr 300 2 hr
40.degree. C./hr .circleincircle. 55 9.5 .circleincircle. Example
20 4.0 80.degree. C./min 350 10 sec 80.degree. C./min
.circleincircle. 59 9.5 .circleincircle. Example 21 8.0 40.degree.
C./hr 250 4 hr 40.degree. C./hr .circleincircle. 51 9.3
.circleincircle. Example 22 8.0 80.degree. C./min 350 10 sec
80.degree. C./min .circleincircle. 59 9.2 .circleincircle. Example
23 2.0 40.degree. C./hr 250 4 hr 40.degree. C./hr .circleincircle.
53 9.8 .circleincircle. Example 24 2.0 80.degree. C./min 350 10 sec
80.degree. C./min .circleincircle. 52 9.6 .circleincircle. Example
25 4.0 40.degree. C./hr 250 4 hr 40.degree. C./hr .circleincircle.
54 9.7 .circleincircle. Example 26 4.0 80.degree. C./min 350 10 sec
80.degree. C./min .circleincircle. 51 9.5 .circleincircle. Example
27 4.0 80.degree. C./min 350 10 sec 80.degree. C./min .largecircle.
77 9.5 .circleincircle. Example 28 4.0 80.degree. C./min 350 10 sec
80.degree. C./min .largecircle. 75 9.5 .circleincircle. Comparative
2.0 Without final annealing X Perforated 7.5 .largecircle. example
1 Comparative 2.0 Without final annealing X Perforated 7.4
.largecircle. example 2 Comparative 2.0 Without final annealing X
350 8.5 .largecircle. example 3 Comparative 0 Without final
annealing X Perforated 7.6 .largecircle. example 4 Comparative 11
Without final annealing .circleincircle. Generation of cracks
during forming example 5 Note) Penetration of filler alloy:
.circleincircle. No penetration, .largecircle. Slight penetration,
X Penetrated Formability: .circleincircle. No cracks, .largecircle.
No cracks, but slightly poor in elongation
[0050] Table 1 shows that all the composite materials in Examples 3
to 15 were excellent in corrosion resistance with small degrees of
penetration of the filler alloy and shallow corrosion pits after
the corrosion test. Substantially no penetration of the filler
alloy was observed and corrosion resistance of the composite
materials was also excellent in the composite materials in Examples
1, 2, and 16 to 28 since the composite materials were kept at
540.degree. C. for 2 hours in the course of the cooling step in the
homogenization treatment. Formability of the composite materials
Nos. 3 to 28 was excellent due to final annealing after giving a
strain, and no cracks by forming were found. On the other hand, in
Comparative Examples 1 to 3 which were produced by applying the
homogenization treatment under the conditions outside of the range
defined in the present invention, penetrations of the filler alloy
were observed at the portions having low degree of forming, and
perforating corrosion pits or very deep corrosion pits were
observed after the corrosion test. Penetration of the filler alloy
was observed with occurrence of perforating pits after the
corrosion test in Comparative Example 4, since no strain was given
in this example. Cracks were caused at a step of forming the
composite material into the shape of a refrigerator flow passageway
in Comparative Example 5, since the percentage of forming for
giving a strain was too high as compared with that in the
conditions defined in the present invention.
[0051] Industrial Applicability
[0052] The method of the present invention is favorable as a
production method of an aluminum alloy composite material for a
brazed product produced by being assembled by brazing after
forming. In more detail, the method is favorable for producing a
material preferable, for example, as an aluminum alloy composite
sheet suitable for a laminate for forming a flow passageway of a
stacked-type evaporator and a stacked-type oil cooler in a heat
exchanger, for a header plate of a radiator and the like.
[0053] Further, the aluminum alloy composite material of the
present invention is excellent in formability especially for a heat
exchanger. During the brazing step, the amount of diffusion of the
filler alloy into the core alloy is small and spread of the filler
alloy is satisfactory. Thus the composite material of the present
invention is preferable as the aluminum alloy composite material
excellent in mechanical strength, corrosion resistance and
formability after brazing.
[0054] Having described our invention as related to the present
embodiments, it is our intention that the invention not be limited
by any of the details of the description, unless otherwise
specified, but rather be construed broadly within its spirit and
scope as set out in the accompanying claims.
* * * * *