US20230193431A1

US20230193431A1 - Aluminum alloy clad material

Info

Publication number: US20230193431A1
Application number: US18/000,362
Authority: US
Inventors: Yoshiki Mori; Michihide Yoshino; Masakazu Edo; Shohei IWAO; Hideyuki Miyake; Yousuke Uchida; Nobuhiro Honma; Shogo Yamada
Original assignee: Denso Corp; MA Aluminum Corp
Current assignee: Denso Corp; MA Aluminum Corp
Priority date: 2020-06-30
Filing date: 2021-06-21
Publication date: 2023-06-22
Also published as: JP2022022649A; WO2022004460A1; JP7265506B2; CN115867685A; DE112021003472T5

Abstract

The aluminum alloy clad material includes a core material and sacrificial materials disposed on both surfaces of the core material, the composition of the core material contains, by mass %, Mn: 0.7% to 1.8%, Si: 0.3% to 1.3%, Fe: 0.05% to 0.7% and Zn: 0.5% to 3.0% with a remainder consisting of Al and inevitable impurities, the composition of the sacrificial material contains, by mass %, Mn: 0.005% to 0.7%, Fe: 0.05% to 0.3% and Zn: 1.0% to 4.0% with a remainder consisting of Al and inevitable impurities, an amount of Zn in the sacrificial material is larger than an amount of Zn in the core material by 0.2% or more, and the potential of the core material after a brazing heat treatment is within a range of −700 to −870 mV.

Description

TECHNICAL FIELD

The present invention relates to an aluminum alloy clad material having an excellent sacrificial anode effect.
Priority is claimed on Japanese Patent Application No. 2020-113168, filed Jun. 30, 2020, the content of which is incorporated herein by reference.

BACKGROUND ART

In recent years, there has been an increasing demand for heat exchangers for cars that are intended for air conditioning in vehicles or the cooling of engine oil or the like. These heat exchangers need to be highly corrosion-resistant since the outside is exposed to corrosive environments due to salts or dew condensation water and the cooling water flow path of the inside is also an environment susceptible to corrosion.
Furthermore, since heat exchangers for the vehicles need to be joined to each of other members by a brazing heat treatment, in that use, aluminum alloy clad materials composed of a sacrificial material, a core material and a brazing filler metal are commonly used. However, heat exchangers that are used in such a way have a variety of forms and also may have a complex structure, and, for example, there is a case where a fin having a sacrificial effect is disposed to provide the anticorrosion property.
Patent Document 1 or Patent Document 2 has proposed an aluminum alloy clad material that imparts a sacrificial effect to fins.
In Patent Document 1, Mg is contained in a core material, thereby increasing the strength. In Patent Document 2, Sn is contained in a sacrificial material, thereby heightening a sacrificial anode effect.

CITATION LIST

[Patent Document]

[Patent Document 1]

Japanese Unexamined Patent Application, First Publication No. H5-125477

[Patent Document 2]

Japanese Patent No. 2607245

SUMMARY OF INVENTION

Technical Problem

Incidentally, in order to provide a sacrificial anticorrosion property to a tube by using a fin, there is a need to set the fin to a baser (lower) potential than the tube. On the other hand, when the potential is set to be too base (low), the corrosion rate of the fin becomes excessively fast, the fin is consumed early, and the sacrificial anode effect disappears.
Furthermore, in a case where a large amount of a flux is applied during brazing or a case where brazing is carried out by vacuum brazing, the corrosion behavior of the fin deteriorates due to the evaporation of Zn in the material during brazing, and the sacrificial anode effect disappears due to the early consumption of the fin.
The present invention has been made in consideration of the above-described circumstances, and an objective of the present invention is to provide an aluminum alloy clad material enabling appropriate sacrificial anticorrosion property by setting the potential of a material as an appropriate value.

Solution to Problem

In a first aspect of an aluminum alloy clad material of the present invention, the aluminum alloy clad material includes a core material and sacrificial materials disposed on both surfaces of the core material, a composition of the core material contains, by mass %, Mn: 0.7% to 1.8%, Si: 0.3% to 1.3%, Fe: 0.05% to 0.7% and Zn: 0.5% to 3.0% with Al balance containing inevitable impurities, a composition of the sacrificial materials contains, by mass %, Mn: 0.005% to 0.7%, Fe: 0.05% to 0.3% and Zn: 1.0% to 4.0% with Al balance containing inevitable impurities, an amount of Zn in the sacrificial materials is larger than an amount of Zn in the core material by 0.2% or more by mass %, and the potential of the core material after a brazing heat treatment is within a range of −700 to −870 mV.
A second aspect of the aluminum alloy clad material according to the above-described aspect, in which the potential difference between each of the sacrificial materials and the core material is 20 to 100 mV.
A third aspect of the aluminum alloy clad material according to the above-described aspect, in which an amount of a Mn solid solution in the core material after the brazing heat treatment is larger than an amount of a Mn solid solution in each of the sacrificial materials by 0.2% or more by mass %.

Advantageous Effects of Invention

According to the aluminum alloy clad material of the present invention, when the potential of a material is set as an appropriate value, a favorable sacrificial anode effect can be obtained by adjusting the potential difference from a brazing opposite material to be an appropriate value.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a view showing a cross section of an aluminum alloy clad material of an embodiment of the present invention.

FIG. 2 is a perspective view of a heat exchanger manufactured using the aluminum alloy clad material of the embodiment of the present invention.

DESCRIPTION OF EMBODIMENT

Hereinafter, an embodiment of the present invention will be described.
An aluminum alloy clad material of the present embodiment includes a core material and sacrificial materials disposed on both surfaces of the core material, the composition of the core material contains, by mass %, Mn: 0.7% to 1.8%, Si: 0.3% to 1.3%, Fe: 0.05% to 0.7% and Zn: 0.5% to 3.0% with Al balance containing inevitable impurities, the composition of the sacrificial materials contains, by mass %, Mn: 0.005% to 0.7%, Fe: 0.05% to 0.3% and Zn: 1.0% to 4.0% with Al balance containing inevitable impurities, the amount of Zn in the sacrificial materials is larger than the amount of Zn in the core material by 0.2% or more, and the potential of the core material after a brazing heat treatment is within a range of −700 to −870 mV.
In addition, the potential difference between each of the sacrificial materials and the core material is preferably 20 to 100 mV.
In addition, the amount of the Mn solid solution in the core material after the brazing heat treatment is preferably larger than the amount of the Mn solid solution in each of the sacrificial materials by 0.2% or more by mass %.
Hereinafter, reasons for limiting technical items that are regulated in the present embodiment will be described. The amounts of components that are contained in the sacrificial material and the core material are expressed in the unit of “mass %”.
[Core Material]

Mn: 0.7% to 1.8%

Mn is an element that improves the strength. However, when the amount is small, a desired effect cannot be sufficiently obtained, and, when Mn is excessively contained, the manufacturability (castability and rollability) is degraded. For these reasons, the amount of Mn is set within the above-described range. For the same reasons, it is desirable that the lower limit of the amount of Mn is set to 0.7% and the upper limit is set to 1.6%.

Si: 0.3% to 1.3%

Si is an element that improves the strength. However, when the amount of Si is small, a desired effect cannot be sufficiently obtained, and, when Si is excessively contained, the melting point decreases, and thus fins buckle during brazing heat treatments, and the brazability deteriorates. For these reasons, in a case where Si is contained, the amount of Si is set within the above-described range. For the same reasons, it is desirable that the lower limit is set to 0.3% and the upper limit is set to 1.1%.

Fe: 0.05% to 0.7%

Fe is an element that improves the strength. However, when the amount is excessive, a large intermetallic compound is generated during casting, the manufacturability is degraded, and the anticorrosion property also deteriorates. In addition, regarding the lower limit, since an impurity is present in a raw material during casting, when the amount is set to less than the lower limit, the manufacturing cost increases. For these reasons, the amount of Fe is set within the above-described range. For the same reasons, it is desirable that the lower limit is set to 0.05% and the upper limit is set to 0.4%.

Zn: 0.5% to 3.0%

Zn is contained to heighten a sacrificial anode effect. However, when the amount of Zn is small, a desired effect cannot be obtained, and, when the amount is excessive, the sacrificial anode effect disappears early due to the acceleration of the corrosion rate. For the same reasons, it is desirable that the lower limit is set to 1.0% and the upper limit is set to 2.5%.

[Sacrificial Material]

The sacrificial materials are disposed on both surface of the core material. The sacrificial materials on the individual surfaces may have the same composition or may have different compositions within the range of the following composition.

Mn: 0.005% to 0.7%

Mn is contained to improve the strength. However, when the amount is excessive, the manufacturability (castability and rollability) is degraded. Furthermore, when the amount of Mn in the sacrificial material becomes more excessive than the amount of Mn in the core material, after the brazing heat treatment, there is no difference in the amount of Mn that forms solid solutions in the sacrificial material and the core material, up to the core material is corroded while the sacrificial material remains, and the corrosion behavior deteriorates. In addition, regarding the lower limit, since an impurity is present in a raw material during casting, when the amount is set to less than the lower limit, the manufacturing cost increases. For these reasons, the amount of Mn is set within the above-described range. For the same reasons, it is desirable that the lower limit of the amount of Mn is set to 0.005% and the upper limit is set to 0.5%.

Fe: 0.05% to 0.3%

Fe is contained to improve the strength. However, when the amount is excessive, a large intermetallic compound is generated during casting, which degrades the manufacturability and also degrades the anticorrosion property. In addition, regarding the lower limit, since an impurity is present in a raw material during casting, when the amount is set to less than the lower limit, the manufacturing cost increases. For these reasons, the amount of Fe is determined within the above-described range. For the same reasons, the upper limit of the amount of Fe is desirably set to 0.2%.

Zn: 1.0% to 4.0%

Zn heightens the sacrificial anode effect. However, when the amount is too small, a desired effect cannot be obtained, pores are generated or up to the core material is corroded while the sacrificial material remains, and the corrosion behavior deteriorates. On the other hand, when the amount is excessive, the sacrificial anode effect disappears early due to the acceleration of the corrosion rate. Furthermore, early corrosion of a fillet occurs. For these reasons, the amount of Zn is determined within the above-described range.
For the same reasons, it is desirable that the lower limit of the amount of Zn is set to 1.5% and the upper limit is set to 3.5%.
As an inevitable impurity in the sacrificial material, each of Si, Cu, Mg, Cr, Ti and the like may be contained to an extent of 0.05% or less. In addition, regarding Si, containing up to 0.1% does not make any difference.

[Relationship Between Core Material and Sacrificial Material]

The amount of Zn in the sacrificial material is larger than the amount of Zn in the core material by 0.2% or more by mass %.
When the amount of Zn in the sacrificial material is larger than the amount of Zn in the core material by 0.2% or more, the sacrificial material corrodes earlier, and the corrosion behavior of fins improves. In a case where the amount of Zn in the sacrificial material is smaller than the amount of Zn in the core material, corrosion proceeds up to the core material while the sacrificial material remains, and the corrosion behavior deteriorates. The difference between the amount of Zn in the sacrificial material and the amount of Zn in the core material is more preferably 0.5% to 2.5% and still more preferably 1.0% to 1.5%.
After the brazing heat treatment, the amount of the Mn solid solution in the core material is preferably larger than the amount of the Mn solid solution in the sacrificial material by 0.2% or more by mass %.
During the brazing heat treatment, since the elements in the materials diffuse, Zn which is added to the sacrificial material diffuses into the core material. In such a case, the potential difference between the sacrificial material and the core material becomes small, which makes it easy for corrosion to proceed in the sheet thickness direction. On the other hand, since Mn rarely diffuses during the brazing heat treatment, even in a case where the potential difference between the sacrificial material and the core material is small, when the amount of the Mn solid solution in the core material is set to be larger than that in the sacrificial material, the potential difference near the interface between the sacrificial material and the core material becomes large, the sacrificial material corrodes earlier, and the corrosion behavior of fins improves. For the above-described reasons, the amount of the Mn solid solution is determined within the above-described range.
The amount of the Mn solid solution in the core material after the brazing heat treatment is preferably larger than the amount of the Mn solid solution in the sacrificial material by 0.3% or more.
As the brazing heat treatment, as an example, the aluminum alloy clad material is heated up to 600° C. from room temperature (5° C. to 40° C.) for 20 minutes and held at 600° C. for three minutes. This will also be true below. However, as the present embodiment, the brazing conditions are not limited to the above description.

[Potential]

The potential of the core material after the brazing heat treatment is within a range of −720 mV to −870 mV.
When the core material has a predetermined potential, the sacrificial anode effect can be obtained. When the potential is too high, a desired effect cannot be obtained, and, when the potential is too low, the sacrificial anode effect disappears early due to the acceleration of the corrosion rate.
The potential of the core material after the brazing heat treatment is preferably within a range of −730 mV to −870 mV and more preferably within a range of −770 mV to −840 mV.
The potential difference between the sacrificial material and the core material (core material potential−sacrificial material potential) is preferably 20 mV to 100 mV.
When the potential difference is within the above-described range, the corrosion behavior of fins improves. When the potential difference is too small, the core material also corrodes while the sacrificial material remains, and the corrosion behavior deteriorates. When the potential difference is excessive, the sacrificial anode effect disappears early due to the acceleration of the corrosion rate.
The potential difference between the sacrificial material and the core material is more preferably in a range of 40 mV to 100 mV.
Hereinafter, an example of a method for manufacturing the aluminum alloy clad material of the present embodiment will be described.
An aluminum alloy for the core material and an aluminum alloy for the sacrificial material each having the composition of the present embodiment are prepared. These alloys can be manufactured by a normal method, and the manufacturing method is not particularly limited. For example, the alloys can be manufactured by the semi-continuous casting.
As the aluminum alloy for the core material, an alloy having a composition containing, by mass %, Mn: 0.7% to 1.8%, Si: 0.3% to 1.3%, Fe: 0.05% to 0.7% and Zn: 0.5% to 3.0% with Al balance containing inevitable impurities is used.
As the aluminum alloy for the sacrificial material, an alloy having a composition containing, by mass %, Mn: 0.005% to 0.7%, Fe: 0.05% to 0.3% and Zn: 1.0% to 4.0% with Al balance containing inevitable impurities is used.
Regarding the selection of the compositions, the compositions are desirably set such that the amount of Zn in the sacrificial material is larger than the amount of Zn in the core material by 0.2% or more by mass %.
After the aluminum alloy for the core material or the aluminum alloy for the sacrificial material is melted, a homogenization treatment can be carried out as desired.
In the homogenization treatment, Mn that has formed a solid solution in the supersaturation state in the matrix during casting is precipitated as an intermetallic compound. Since the size or dispersion amount of the intermetallic compound that is precipitated is affected by the temperature and time of the homogenization treatment, it is necessary to select appropriate heat treatment conditions.
Ordinarily, when the heat treatment is carried out at a high temperature, the precipitation and growth of the intermetallic compound are accelerated, and the Mn solid solubility becomes low. Conversely, when the heat treatment is carried out at a low temperature, the precipitation and growth of the intermetallic compound are suppressed, and the Mn solid solubility becomes high. In addition, when the intermetallic compound that is precipitated by the homogenization treatment is refined, the precipitate is melted again by the brazing heat treatment and forms a solid solution in the materials, and thus the amount of the Mn solid solution after the brazing heat treatment increases.
On the other hand, when the intermetallic compound that is precipitated by the homogenization treatment is coarsened, during the brazing heat treatment, the compound is partially melted, but not completely melted, and thus the amount of the Mn solid solution after the brazing heat treatment decreases.
In the present embodiment, since the corrosion behavior of fins is improved by setting the amount of the Mn solid solution in the core material to be larger than the amount of the Mn solid solution in the sacrificial material by 0.2% or more by mass %, it is necessary to control the amount of the Mn solid solution by appropriately combining the homogenization treatment or the hot rolling and annealing temperature conditions.
In the present embodiment, since the corrosion behavior of fin materials is improved by the difference in the amount of the Mn solid solution between the core material and the sacrificial material, the homogenization treatment is carried out on the core material at 400° C. to 500° C. for four to 16 hours, and a precipitate is finely precipitated. On the other hand, on the sacrificial material, basically, the homogenization treatment is not carried out; however, when the homogenization treatment is carried out at 500° C. to 600° C., which is a higher temperature than that for the core material, for four to 16 hours, and a precipitate in the sacrificial material is coarsened compared with that in the core material, the amount of Mn that forms a solid solution in the sacrificial material is decreased, and the corrosion behavior is improved.
The aluminum alloy for the core material or the aluminum alloy for the sacrificial material are made into sheet materials by hot rolling. In addition, the aluminum alloys may also be made into sheet materials by continuous casting rolling.
In the hot rolling, it is possible to set the finishing temperature.
Usually, hot rolling is loaded at a high temperature of approximately 500° C., and, after the hot rolling, the sheet materials are coiled and cooled to room temperature.
In this case, since the time during which the aluminum alloys are held at high temperature changes depending on the finishing temperature of the hot rolling, the finishing temperature has an influence on the precipitation behaviors of the intermetallic compound.
The sheet materials are hot-rolled and then further cold-rolled, whereby an aluminum alloy clad material having a desired thickness can be obtained.
As the present embodiment, the cladding rate in the clad material is not particularly limited, but 5% to 25% of the thickness of the sacrificial material on one surface, 50% to 90% of the core material thickness and the like are used.
In the above description, the sacrificial material has been described to be directly laminated on the core material, but may be laminated through a different layer.
The clad material is set to a thickness of, for example, 0.05 to 0.20 mm by cold rolling. In the middle of the cold rolling, intermediate annealing may be carried out.
The conditions for the intermediate annealing can be selected from, for example, ranges of 150° C. to 400° C. and one to 10 hours. However, when the intermediate annealing temperature becomes a high temperature, the precipitation and growth of the intermetallic compound are accelerated during the annealing, and the difference in the amount of the Mn solid solution between the sacrificial material and the core material becomes small, and thus the intermediate annealing is desirably carried out at a temperature of 300° C. or lower.
These sheet materials are disposed and laminated such that a sacrificial material 3 a is disposed on one surface of a core material 2 and a sacrificial material 3 b is disposed on the other surface as shown in FIG. 1 , and the laminated materials are cladded at appropriate cladding rates in the above-described state, whereby an aluminum alloy clad material 1 is produced. The sacrificial materials 3 a and 3 b may have the same composition or may have different compositions within the range of the above-described composition.
The obtained clad material can be used as, for example, a tube material for a heat exchanger, a fin and the like. The sacrificial material 3 a or 3 b and the core material 2 have a potential difference of 20 mV to 100 mV.
A fin material for a heat exchanger is joined by brazing to an appropriate member to be brazed such as a tube.
As the present embodiment, the material, shape and the like of the member to be brazed are not particularly limited, and an appropriate aluminum material can be used.
The heat treatment conditions during brazing are not particularly limited except that the fin material and the member to be brazed are heated up to 590° C. to 615° C., and it is possible to carry out the brazing under conditions under which, for example, the fin material and the member to be brazed are heated at a heating rate at which the time taken for the temperature to reach the target temperature from 550° C. becomes one minute to 10 minutes, held at the target temperature of 590° C. to 615° C. for one minute to 20 minutes, then, cooled to 300° C. at 50 to 100° C./min and then cooled to room temperature in the air. The amount of the Mn solid solution in the core material desirably becomes larger than the amount of the Mn solid solution in the sacrificial material by 0.2% or more by mass % after the brazing heat treatment.
In addition, after the brazing, the potential of the core material is within a range of −720 to −870 mV.
In the core material of the member to be brazed, which is a member to provide the anticorrosion property, only the potential of the core material is regulated, in consideration of ordinarily-used Al—Mn-based alloys.
The potential is prepared depending on the compositions of the materials and the manufacturing conditions.
FIG. 2 shows a heat exchanger for an aluminum vehicle 4 for which fins 5 are formed using the aluminum alloy clad material and aluminum alloy tubes 6 are used as a member to be brazed. The fins 5 and the tubes 6 are combined with a reinforcing material 7 and a header plate 8 and brazed to obtain the heat exchanger for an aluminum vehicle 4.

Examples

Aluminum alloys for sacrificial materials and core materials were cast by semi-continuous casting based on compositions (the remainder was A1 and inevitable impurities) shown in Table 1 and Table 2. As the aluminum alloys for sacrificial materials and core materials, alloys having a composition (the remainder was A1 and inevitable impurities) shown in Table 1 and Table 2 were used. The sacrificial materials contained Si in the compositions shown in Table 1 and Table 2 as an inevitable impurity. Next, homogenization treatments were carried out under conditions shown in Table 3 and Table 4, hot rolling and cold rolling were carried out, then, intermediate annealing was carried out, and sheet materials were rolled up to a sheet thickness of 0.2 mm by cold rolling, thereby producing Temper H14 sheet materials (clad materials). The clad materials were produced such that the cladding rate of the sacrificial material on one surface became 10%.
On test materials from the obtained clad materials of Examples 1 to 33 and Comparative Examples 1 to 16, the following evaluation methods were carried out. Individual evaluation results are shown in Table 3 and Table 4.

[Corrosion Evaluation of Test Material]

A brazing heat treatment was carried out on the test material having a sheet thickness of 0.20 mm after final rolling, and the test material was used as a material that was to be subjected to a corrosion test.

[Evaluation of Sacrificial Anticorrosion Property]

The test material having a sheet thickness of 0.20 mm, which was corrugated, was combined to a brazing filler metal surface of a brazing sheet having a sheet thickness of 0.3 mm (cladding configuration: brazing filler metal (10%)/core material (75%)/sacrificial material (15%), brazing filler metal: JIS A 4045 alloy, core material: Al-1.OMn-0.5Cu alloy, sacrificial material: JIS A 7072 alloy), and a brazing heat treatment was carried out.
As the brazing conditions, a brazing-equivalent heat treatment in which a sample of the test material to which 10 g/m²of K_1-3AlF_4-6had been applied as a flux was heated up to 600° C. from room temperature (20° C.) in a high-purity nitrogen gas atmosphere for 20 minutes, held at 600° C. for three minutes and then cooled to 300° C. at 60° C./minute was carried out.
After that, a sacrificial material surface of the test material was masked, and an immersion test was carried out using OY water (Cl⁻: 195 ppm, SO₄ ²⁻: 60 ppm, Cu²⁺: 1 ppm, Fe³⁺: 30 ppm remainder pure water) in a state where the test material and the brazing filler metal surface of the brazing sheet were exposed. As the test conditions, room temperature (20° C.)×16 h+88° C.×8 h (no stirring) was regarded as a one-day cycle, and the test material and the brazing sheet were immersed for two weeks in the corrosion evaluation of a fin and for eight weeks in the evaluation of sacrificial anticorrosion property. After that, a corrosion product was removed with chromium acid phosphate, and the corrosion behavior of the test material and the depth of a corroded part of the brazing sheet were evaluated.

[Corrosion Evaluation Standards of Test Material]

D: Early corrosion of the core material occurs (core material: only the sheet thickness center part corrodes earlier).
C: Partial pitting corrosion is observed (a part of the sacrificial material is left undissolved, and the core material corrodes).
B: The majority is surface corrosion, but extremely partial pitting corrosion is observed.
A: The whole surface is surface corrosion.

[Evaluation Standards of Sacrificial Anticorrosion Property]

D: A through hole is generated in the brazing sheet.
C: The depth of corrosion occurring in the brazing sheet is half of the sheet thickness (0.125 mm) or more and less than penetration.
B: The depth of corrosion occurring in the brazing sheet is less than half of the sheet thickness (0.125 mm).
A: The depth of corrosion occurring in the brazing sheet is less than ¼ of the sheet thickness (0.06 mm).

[Measurement of Natural Potential]

The natural potentials of a core material and a sacrificial material in the fin were measured using a silver/silver chloride electrode in a solution obtained by adjusting the pH of a 5% NaCl solution to 3.0 with acetic acid.
[Evaluation of Strength after Brazing Heat Treatment]
A material after a brazing-equivalent heat treatment was milled to a JIS No. 5 test piece shape, and the strength was measured by a tensile test.
[Evaluation Standards of Strength after Brazing Heat Treatment]
D: The tensile strength after the brazing heat treatment is less than 90 MPa.
C: The tensile strength after the brazing heat treatment is 90 MPa or more and less than 120 MPa.
B: The tensile strength after the brazing heat treatment is 120 MPa or more.

[Measurement of Mn Solid Solubility]

A fin material after a brazing heat treatment was etched with a 10% NaOH solution, and a sample only composed of a core material and a sacrificial material was produced. After that, the core material and the sacrificial material were each dissolved by the thermal phenol method, and the obtained solution was subjected to ICP emission spectroscopic analysis, thereby measuring the solid solubility amount of Mn.

	TABLE 1

	Difference in the amount
	of Zn between sacrificial	Potential of

Alloy composition of sacrificial material

Alloy composition of core material

material and core material

core material

Test

(mass %)

(mass %) (* sacrificial

after brazing

material No.	Mn	Si	Fe	Zn	Mn	Si	Fe	Zn	material − core material)	(mV)

Example	1	0.005	0.02	0.1	2.0	1.0	0.7	0.3	1.5	0.5	−775
	2	0.5	0.02	0.2	1.5	1.0	0.7	0.3	1.0	0.5	−730
	3	0.5	0.03	0.2	1.5	1.0	0.7	0.3	1.2	0.3	−730
	4	0.5	0.01	0.2	1.7	1.0	0.7	0.3	1.2	0.5	−730
	5	0.005	0.02	0.1	3.5	1.0	0.5	0.4	2.0	1.5	−820
	6	0.005	0.01	0.1	2.5	0.7	0.5	0.4	1.0	1.5	−765
	7	0.005	0.02	0.1	2.5	0.7	1.0	0.4	1.0	1.5	−750
	8	0.005	0.03	0.05	2.5	0.7	1.0	0.4	1.0	1.5	−745
	9	0.005	0.02	0.05	2.5	1.0	0.3	0.4	1.0	1.5	−760
	10	0.005	0.01	0.1	2.5	1.2	0.3	0.4	1.0	1.5	−755
	11	0.005	0.01	0.1	2.5	0.7	0.3	0.1	1.0	1.5	−770
	12	0.005	0.02	0.1	2.5	0.7	0.3	0.2	1.5	1.0	−790
	13	0.005	0.01	0.1	2.5	0.7	0.3	0.2	1.5	1.0	−800
	14	0.005	0.01	0.1	2.5	0.7	0.3	0.2	2.0	0.5	−840
	15	0.005	0.02	0.1	3.5	0.7	0.3	0.2	3.0	0.5	−870
	16	0.005	0.04	0.1	2.0	1.8	1.3	0.7	0.5	1.5	−710
	17	0.005	0.03	0.1	2.0	1.8	1.3	0.7	1.0	1.0	−730
	18	0.005	0.01	0.1	1.5	1.8	1.3	0.7	1.0	0.5	−730
	19	0.005	0.01	0.1	1.5	1.8	1.3	0.7	1.0	0.5	−710
	20	0.5	0.04	0.3	2.0	1.8	1.3	0.7	1.0	1.0	−730
	21	0.005	0.03	0.1	4.0	1.8	1.3	0.7	3.0	1.0	−850
	22	0.005	0.02	0.1	2.5	1.8	0.7	0.4	1.0	1.5	−760
	23	0.7	0.04	0.3	2.0	1.2	0.7	0.3	1.5	0.5	−770
	24	0.7	0.04	0.3	2.0	1.0	0.5	0.3	1.5	0.5	−765
	25	0.005	0.01	0.1	1.0	1.0	0.5	0.4	0.5	0.5	−725

	TABLE 2

	Difference in the amount
	of Zn between sacrificial	Potential of

Alloy composition of sacrificial material

Alloy composition of core material

material and core material

core material

Test

(mass %)

(mass %) (* sacrificial

after brazing

material No.	Mn	Si	Fe	Zn	Mn	Si	Fe	Zn	material − core material)	(mV)

Example	26	0.005	0.04	0.1	1.0	0.7	0.3	0.1	0.7	0.3	−725
	27	0.005	0.02	0.1	1.0	1.6	1.0	0.4	0.5	0.5	−710
	28	0.005	0.04	0.1	4.0	1.0	0.5	0.4	1.5	2.5	−765
	29	0.7	0.04	0.3	4.0	1.0	0.5	0.4	1.5	2.5	−765
	30	0.7	0.04	0.3	2.5	1.6	1.0	0.4	1.5	1.0	−760
	31	0.7	0.04	0.3	2.5	1.2	0.5	0.4	1.5	1.0	−765
	32	0.7	0.02	0.3	2.0	1.2	0.7	0.3	1.5	0.5	−770
	33	0.7	0.04	0.3	2.0	1.2	0.7	0.3	1.5	0.5	−770

Comparative

1

No sacrificial material

1.0

0.7

0.3

1.5

—

−775

Example

2

0.7

0.04

0.3

0.5

0.7

0.4

1.0

−0.5

−750

3	0.005	0.02	0.1	2.0	2.5	1.0	0.4	1.5	Material production is impossible due to
									rupture during rolling
4	0.005	0.02	0.1	2.0	1.2	2.0	0.4	1.5	Evaluation is impossible due to fin
									buckling during brazing
5	0.005	0.01	0.1	2.0	1.6	1.0	1.0	1.5	Material production is impossible due to
									rupture during rolling

6

1.0

0.03

0.3

1.5

0.7

0.3

1.0

0.5

−780

	7	0.1	0.04	1.0	2.0	1.2	0.7	0.3	1.5	Material production is impossible due to
										rupture during rolling

8	0.005	0.01	0.2	1.0	1.6	0.7	0.4	0.0	1.0	−680
9	0.005	0.01	0.2	2.0	1.6	0.7	0.4	0.0	2.0	−680
10	0.005	0.02	0.2	3.0	1.6	0.7	0.4	0.0	3.0	−680
11	0.005	0.01	0.2	2.0	1.6	0.7	0.4	0.3	1.7	−690
12	0.005	0.03	0.2	4.5	1.6	0.7	0.4	4.0	0.5	−850
13	0.005	0.04	0.2	1.0	0.7	0.3	0.3	4.0	−3.0	−900
14	0.005	0.04	0.1	2.0	0.3	0.3	0.4	1.0	1.0	−775
15	0.005	0.02	0.1	2.0	0.7	0.1	0.4	1.0	1.0	−760
16	0.005	0.02	0.1	2.0	0.5	0.1	0.2	1.0	1.0	−770

	TABLE 3

	Difference in

			the amount of	Potential
			Mn solid solu-	difference
			tion between	between core
	Homogeniza-		core material	material and
Homogeniza-	tion treatment	Inter-	and sacrifi-	sacrificial
tion treatment	conditions of	mediate	cial material	material	Strength	Evaluation		Evaluation
conditions of	sacrificial	annealing	after brazing	after brazing	after	of strength		of
core material	material	conditions	(mass %) (*	(mV) (* core	brazing	after	Corrosion	sacrificial

Test	(temperature:	(temperature:	(temperature:	core material −	material −	heat	brazing	Evaluation	anti-
material	° C., time:	° C., time:	° C., time:	sacrificial	sacrificial	treatment	heat	of Test	corrosion
No.	hour)	hour)	hour)	material)	material)	(MPa)	treatment	Material	property

Example	1	450° C., 10 h	—	300° C., 4 h	0.3	65	112	C	A	A
	2	550° C., 4 h	—	400° C., 3 h	0.1	40	106	C	B	A
	3	400° C., 10 h	—	200° C., 7 h	0.3	40	110	C	A	A
	4	400° C., 10 h	580° C., 4 h	200° C., 7 h	0.5	40	109	C	A	A
	5	450° C., 10 h	—	300° C., 4 h	0.3	80	105	C	A	A
	6	400° C., 10 h	—	200° C., 7 h	0.3	125	100	C	A	B
	7	400° C., 10 h	—	200° C., 7 h	0.2	140	120	B	A	B
	8	400° C., 10 h	—	400° C., 3 h	0.1	145	118	B	B	B
	9	400° C., 10 h	—	200° C., 7 h	0.4	130	101	C	A	B
	10	400° C., 10 h	—	200° C., 7 h	0.5	135	106	C	A	B
	11	400° C., 10 h	—	200° C., 7 h	0.3	120	92	C	A	B
	12	400° C., 10 h	—	200° C., 7 h	0.3	90	96	C	A	A
	13	500° C., 6 h	—	400° C., 3 h	0.2	80	90	C	A	A
	14	450° C., 10 h	—	300° C., 4 h	0.3	50	94	C	A	A
	15	500° C., 6 h	—	400° C., 3 h	0.2	10	92	C	B	C
	16	500° C., 6 h	—	300° C., 4 h	0.5	130	145	B	B	C
	17	500° C., 6 h	—	300° C., 4 h	0.5	110	142	B	A	B
	18	500° C., 6 h	—	330° C., 4 h	0.5	90	144	B	A	A
	19	400° C., 10 h	—	200° C., 7 h	0.8	110	151	B	A	B
	20	500° C., 6 h	—	270° C., 4 h	0.5	40	153	B	A	A
	21	500° C., 6 h	—	270° C., 4 h	0.5	40	144	B	A	A
	22	500° C., 6 h	—	300° C., 4 h	0.6	120	130	B	A	B
	23	450° C., 10 h	550° C., 4 h	200° C., 7 h	0.2	40	121	B	A	A
	24	550° C., 4 h	—	400° C., 3 h	0.1	15	121	B	C	A
	25	450° C., 10 h	—	300° C., 4 h	0.3	90	108	C	A	A

	TABLE 4

	Difference in

Example	26	400° C., 10 h	—	200° C., 7 h	0.2	90	93	C	A	A
	27	500° C., 6 h	—	300° C., 4 h	0.4	110	138	B	A	B
	28	450° C., 10 h	—	270° C., 4 h	0.3	135	108	C	A	B
	29	450° C., 10 h	580° C., 4 h	270° C., 4 h	0.2	85	110	C	A	A
	30	450° C., 10 h	580° C., 4 h	270° C., 4 h	0.4	40	142	B	A	A
	31	400° C., 10 h	580° C., 4 h	200° C., 7 h	0.4	35	118	C	A	A
	32	550° C., 4 h	—	300° C., 4 h	0.1	10	117	C	C	A
	33	450° C., 10 h	580° C., 4 h	330° C., 4 h	0.3	25	123	B	A	A
Comparative	1	450° C., 10 h	—	400° C., 3 h	—	—	125	B	D	C
Example	2	450° C., 10 h	—	400° C., 3 h	0.1	−5	115	C	D	C

	3	Material production is impossible due to rupture during rolling
	4	Evaluation is impossible due to fin buckling during brazing
	5	Material production is impossible due to rupture during rolling

6

550° C., 4 h

—

400° C., 3 h

−0.3

10

85

D

C

7

Material production is impossible due to rupture during rolling

8	500° C., 6 h	—	400° C., 3 h	0.3	50	118	C	C	D
9	500° C., 6 h	—	400° C., 3 h	0.3	130	121	B	B	D
10	500° C., 6 h	—	400° C., 3 h	0.3	140	119	C	B	D
11	500° C., 6 h	—	400° C., 3 h	0.3	110	123	B	B	D
12	500° C., 6 h	—	400° C., 3 h	0.3	50	119	C	B	D
13	450° C., 10 h	—	400° C., 3 h	0.2	−20	93	C	D	D
14	500° C., 6 h	—	330° C., 4 h	0.1	65	85	D	B	B
15	450° C., 10 h	—	200° C., 7 h	0.3	80	85	D	A	A
16	550° C., 4 h	—	400° C., 3 h	0.1	70	80	D	B	B

In the present examples, the combination of the fin, which corresponds to the clad material of the present invention, and a tube, which is an opposite material, was assumed, and it was clarified that the sacrificial anticorrosion property is provided to the tube and the early consumption of the fin is suppressed by enabling the setting of the potential of the fin with respect to the potential of the tube within an appropriate range. In addition, the sacrificial materials are imparted on both surfaces of the fin, and the potentials of the core material and the sacrificial material in the fin are also set within appropriate ranges, whereby an effect of suppressing corrosion in the sheet thickness direction caused by the early corrosion of the sacrificial material and improving the corrosion behavior is created.
In the present specification, the outer fin was typically used in the description of the objective and the effect, but the present invention is not limited to the outer fin, and the same effect can also be obtained in fins other than the outer fin or other uses.
Hitherto, the present invention has been described based on the embodiment and the examples, but the present invention is not limited to the contents of these descriptions, and appropriate modification of the embodiment is possible within the scope of the present invention.

REFERENCE SIGNS LIST

- 1 Clad material
- 2 Core material
- 3 a Sacrificial material
- 3 b Sacrificial material
- 4 Heat exchanger
- 5 Fin
- 6 Tube

Claims

1. An aluminum alloy clad material, comprising:

a core material; and

sacrificial materials disposed on both surfaces of the core material; wherein;

a composition of the core material comprises, by mass %, Mn: 0.7% to 1.8%, Si: 0.3% to 1.3%, Fe: 0.05% to 0.7% and Zn: 0.5% to 3.0% with an Al balance containing inevitable impurities;

a composition of the sacrificial materials comprises, by mass %, Mn: 0.005% to 0.7%, Fe: 0.05% to 0.3% and Zn: 1.0% to 4.0% with an Al balance containing inevitable impurities;

an amount of Zn in the sacrificial materials is larger than an amount of Zn in the core material by 0.2% or more by mass %; and

a potential of the core material after a brazing heat treatment is within a range of −700 to −870 mV.

2. The aluminum alloy clad material according to claim 1, wherein a potential difference between each of the sacrificial materials and the core material (a core material potential—a sacrificial material potential) is 20 to 100 mV after the brazing heat treatment.

3. The aluminum alloy clad material according to claim 1, wherein an amount of a Mn solid solution in the core material after the brazing heat treatment is larger than an amount of a Mn solid solution in each of the sacrificial materials by 0.2% or more by mass %.

4. The aluminum alloy clad material according to claim 2, wherein an amount of a Mn solid solution in the core material after the brazing heat treatment is larger than an amount of a Mn solid solution in each of the sacrificial materials by 0.2% or more by mass %.