JP3434102B2 - Aluminum alloy heat exchanger with excellent fatigue strength and corrosion resistance - Google Patents

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a heat exchanger for an automobile using an aluminum alloy brazing sheet, and more specifically, the brazing sheet defined in the present invention is made into a tube material by electric resistance sewing or the like.
The present invention relates to an aluminum alloy heat exchanger that is used as it is as a header material in a heat exchanger, has high fatigue strength after brazing, has excellent external and internal corrosion resistance as a heat exchanger, and has excellent heat exchange performance.

[0002]

2. Description of the Related Art A heat exchanger such as a radiator has a plurality of flat tubes (1) integrally formed with corrugated thin fins (2) as shown in FIG. Both ends of the flat tube (1) are opened in the space formed by the header (3) and the tank (4), and the flat tube (1) is passed through from the space on the side of one tank to a high temperature. The refrigerant is sent to the space on the side of the other tank (4), and heat exchanged in the tubes (1) and fins (2) to circulate the refrigerant that has become low temperature.

The tube material and header material of such a heat exchanger are, for example, JIS 3003 alloy (Al-0.15 wt%
Cu-1.1 wt% Mn) is used as a core material, and the inside of the core material, that is, the side which is constantly in contact with the refrigerant is used as a lining material according to JIS7.
072 alloy (Al-1 wt% Zn), and outside the core material is usually JIS 4045 alloy (Al-10 wt% S).
Using a brazing sheet clad with a brazing material such as i), it is integrally assembled by brazing together with other members such as corrugated fins. As the brazing method, a flux brazing method, a nocolock brazing method using a non-corrosive flux, etc. are performed, and brazing is performed by heating to a temperature of around 600 ° C.

By the way, in recent years, heat exchangers have been in the direction of weight reduction and downsizing, and therefore, thinning of materials has been desired. However, when the thickness is reduced by the conventional method, many problems occur. First, there are problems such as destruction of the heat exchanger core due to a decrease in tube fatigue strength, and a marked decrease in corrosion resistance inside the tube.

In the prior art, solid solution strengthening by adding Si and Cu to the core material was effective for increasing the strength of the tube, but a low melting point composition with a large amount of addition may cause melting during brazing and does not melt. Only by solid solution strengthening by adding Si and Cu in the range, there was a limit to achieving high strength with an ultrathin plate thickness of 0.2 mm. Therefore, the inventors of the present invention added Mg and Zn to the sacrificial material and added Al-Mg-Z after the brazing heat.
The n-based compound was precipitated by ageing to increase the strength by age hardening. However, this conventional technique was sufficient up to a tube plate thickness of 0.25 mm, but there was a limit in this technique when the plate thickness became 0.25 mm or less, particularly 0.2 mm. In addition, the cooling rate during brazing was made faster than before and the amount of solid solution was increased to try to increase the age precipitation after brazing, but it was impossible to maintain the target strength.

That is, the plate thickness according to such a conventional technique.
In a heat exchanger consisting of a 0.2 mm tube, in a simulated test of actual vehicle running, when subjected to repeated stress due to cooling ← → heating and stress due to vibration, the fatigue strength gradually decreased, and as a result, the tube tube Burst,
The problem arises that it loses its function as a heat exchanger. In addition, a method of improving strength by adding Mg to the core material and using a Mg ₂ Si compound formed between Si and the core material can be considered. However, if the Mg content of the core material exceeds 0.7%, the brazing material side during brazing There is a problem that the amount of diffusion to the fins increases and brazing with the fins becomes impossible.

Next, in order to increase the strength, Si and C are added to the core material.
When the amount of addition of an element such as u that makes the potential noble increases, the diffusion of Si and Cu from the core material to the sacrificial material further progresses due to the heat applied by the brazing. It is not possible to secure a sufficient potential difference between the sacrificial material and
There is a risk that the tube will penetrate. In this case, the function as a heat exchanger does not work at all.

[0008]

Means for Solving the Problems In the present invention, as a result of intensive studies in view of such a situation, an aluminum alloy brazing sheet having excellent fatigue strength and corrosion resistance after brazing is used.
This is a heat exchanger that is compact, lightweight, and capable of improving thermal efficiency. The aluminum alloy brazing sheet used in the heat exchanger of the present invention has a three-layer structure as shown in FIG. That is, a high-strength aluminum alloy is used as a core material (5), and a brazing material (6) is provided on one surface of the core material and a sacrificial material (7) is provided on the other surface. When assembling the heat exchanger, the brazing material is used on the outside and the sacrificial material is used on the side of the refrigerant passage.

In the present invention, in order to improve the fatigue strength of such a brazing sheet, various studies have been conducted on which part of the brazing sheet should have the highest strength, and the brazing sheet according to the present invention is used. When the tube material and the fin material that has been used conventionally are combined to form a heat exchanger by brazing, Al-Cu is formed at the core material side interface portion near the interface between the core material and the sacrificial material of the brazing sheet. When the —Mg—Zn-based precipitate has the distribution defined in the present invention, the tube material,
As a result, it was found that the heat exchanger exhibits the effects of excellent fatigue strength and corrosion resistance as described above. That is, the inventors of the present invention have formed a very fine Al—C having a maximum diameter of 1 to 50 nm deposited in the matrix at the interface on the core material side.
It was found that the age hardening by the u-Mg-Zn compound greatly affects the fatigue strength of the material.

In order to obtain such a distribution of precipitates, the artificial aging treatment after the heat of brazing is optimum. However,
Under the composition of the core material and the sacrificial material of the brazing sheet according to the present invention, the longest diameter is 1 to 50 nm and the diameter is Al-Cu-Mg-.
In order to distribute Zn-based precipitates of 150 particles / μm ³ or more,
The selection of aging treatment conditions is an important point. That is, according to the investigation by the present inventors, the element diffusion state after the brazing addition heat of Cu in the core material and Mg and Zn in the sacrificial material specified in the present invention by the aging treatment is as shown in FIG. Further, in the figure, a depth of 30 μm from the interface between the sacrificial material and the core material into the core material is the area where age hardening by the Al—Cu—Mg—Zn-based precipitate contributes most, and the heat exchanger according to the present invention. It was found to be a core material part capable of significantly improving the fatigue strength of.

Therefore, as a result of further intensive studies, the present inventors have found that the artificial aging treatment after the heat of brazing is carried out in the temperature range of 80 to 180 ° C. for at least 5 hours or more in the atmosphere or nitrogen atmosphere. It was found that the effect of improving the fatigue strength of the tube was obtained. Especially 90 ~ 140 ℃
Al-Cu-Mg-Zn
It has been found that the aging precipitation of the system compound is remarkably caused at the interface portion on the core material side near the interface between the core material and the sacrificial material, and the fatigue strength of the tube and by extension, the heat exchanger is significantly improved.

The interface portion on the core material side refers to a region from the interface to a depth of about 30 μm on the core material side in the tube thickness direction, and in this portion, the longest diameter 1 to 50 specified in the present invention.
150 nm / μm of Al-Cu-Mg-Zn-based precipitates with nm diameter
By distributing ³ or more, even if a thin tube with a plate thickness of 0.2 mm is used, Si, C
The inventors have newly found that it is possible to provide a heat exchanger whose fatigue strength is dramatically improved, which cannot be imagined by natural solution aging by solid solution strengthening by u or leaving it at room temperature after brazing. is there.

As a pre-stage of the artificial aging treatment,
If the cooling rate after the brazing heat is 80 ° C./min. Or more, which is higher than the conventional 40-60 ° C./min.
It is more preferable to obtain a distribution state of Cu-Mg-Zn-based precipitates. More preferably 400 in the cooling process after brazing
When the cooling rate in the temperature range of up to 200 ° C is 100 ° C / min. Or more, the number density of Al-Cu-Mg-Zn based precipitates is further increased, and the fatigue strength of the heat exchanger is further improved.

The present invention is an aluminum alloy heat exchanger developed on the basis of the above findings, wherein at least C
An aluminum alloy brazing material is clad on one surface of an aluminum alloy core material containing u, and at least Zn on the other surface.
In a heat exchanger obtained by brazing using an aluminum alloy brazing sheet having a three-layer structure in which an aluminum alloy sacrificial material containing Mg and Mg is brazed, the sacrificial material and core material of the brazing sheet constituting the heat exchanger The feature is that Al-Cu-Mg-Zn-based precipitates having a longest diameter of 1 to 50 nm are distributed at 150 pieces / μm ³ or more in the portion from the interface to the core material to a depth of 30 μm. It is what

As the aluminum alloy brazing sheet, Si: 0.2-1.5 wt%, Cu: 0.4-
2.5wt%, Mn: 0.5-2.0wt%, or further Mg: 0.03-0.5wt%, Cr: 0.03-0.3wt%, Z
r: 0.03 to 0.3 wt% and Ti: 0.03 to 0.3 wt%, containing one or more of them, and a brazing material made of an aluminum alloy on one surface of an aluminum alloy core material composed of the balance aluminum and unavoidable impurities. Clad and Z on the other side
n: 1.0 to 6.0 wt%, Mg: 0.5 to 3.5 wt%,
In addition, In: 0.002-0.3wt%, Sn: 0.002-
It is recommended to use an aluminum alloy brazing sheet having a three-layer structure containing one or more of 0.3 wt% and Mn: 1.6 wt% or less, and clad with an aluminum alloy sacrificial material containing the balance aluminum and unavoidable impurities. It is valid.

First, the role of each additive element of the core alloy will be described below. Cu exists in the alloy in a solid solution state and improves the strength. If the Cu content is less than 0.4 wt%, the strength improving effect is not sufficient. Considering corrosion resistance, the upper limit of Cu content is preferably 2.5 wt% or less. Therefore, although Cu is 0.4 to 2.5 wt%, stable characteristics are exhibited especially at 1.0 to 1.5 wt%.

Si contributes to the improvement of strength. Si is 0.2
If it is less than wt%, the strength improving effect is not sufficient and 1.5 wt%
When it exceeds, the coarse compound is formed in the core material, and when corrosion progresses beyond the sacrificial layer, the corrosion resistance is lowered. That is, if a large amount of Si is added to the core material in order to increase the strength, the corrosion resistance of the refrigerant passage constituting member is sharply lowered. Therefore, Si is
The content is 0.2 to 1.5 wt%, but stable characteristics are exhibited especially near 0.5 to 1.0 wt%.

Mn is an element for distributing the intermetallic compound in the alloy and improving the strength without lowering the corrosion resistance. If the amount is less than 0.5 wt%, the strength is not sufficiently improved, and if added in excess of 2.0 wt%, the formability is lowered and the brazing sheet is cracked during processing such as assembly in a heat exchanger. In particular, it shows stable characteristics at 1.0 to 1.5 wt%.

Mg is a solid solution in the alloy and Mg ₂ Si
Exists as a fine precipitation phase of and improves the strength. 0.03
If it is less than wt%, there is no effect of improving strength, and if it exceeds 0.5 wt%, when brazing using a non-corrosive flux, the flux reacts with Mg and brazing cannot be performed.

Cr, Zr, and Ti each have the function of forming a fine intermetallic compound and improving the strength of the alloy.
However, if it is less than 0.03 wt%, there is no effect of improving the strength, and if it is added in excess of 0.3 wt%, the formability is lowered and the brazing sheet is cracked at the time of processing such as assembling to a heat exchanger.

The above are the components of the core alloy of the present invention.
Fe is a typical element as an unavoidable impurity. Fe may be contained as long as it is 1.2 wt% or less. Further, elements other than the above, such as B added for refining the structure of the ingot, may be contained if the content is 0.05 wt% or less.

Next, the brazing alloy will be described. In the present invention, the brazing material is an aluminum alloy, and the composition is not specified. Therefore, it is sufficient to use the conventional Al-Si alloy brazing material. However, in consideration of the fact that the alloy may be melted by the additional heat of brazing when the amount of Si or Cu in the core material is increased, the inventors of the present invention have developed the conventional method, and disclosed in JP-A-7-97651. Low temperature disclosed in the official gazette
(Can be used at 570 to 585 ° C) brazing alloy, namely Al-
Si-Cu-Zn based alloy, for example Al-10wt% Si-
A 1.8 wt% Cu-4.0 wt% Zn alloy brazing material may be used. Fe is 1.0 wt% as an unavoidable impurity.
The following can be contained. However, Fe forms an intermetallic compound when the brazing solidifies, which is the starting point of corrosion. Therefore, the Fe content is preferably 0.5 wt% or less. F
As unavoidable impurities other than e, other elements are 0.
It may be contained if it is 05 wt% or less.

Next, the role of each additive element of the sacrificial alloy will be described. When the sacrificial alloy as in the present invention and a high Cu-added core alloy are combined, Cu added to the core alloy
However, when it is brazed, it diffuses into the sacrificial layer, canceling out the sacrificial effect of the sacrificial layer. Therefore, it is conceivable to increase Zn in the sacrificial material. That is, the sacrificial alloy of the present invention essentially contains Zn and Mg. Specifically, Zn 1.0 to 6.0
wt%, Mg: 0.5-3.5 wt%, or further I
n: 0.002-0.3wt%, Sn: 0.002-0.3wt%, M
n: contains one or more of 1.6 wt% or less,
An aluminum alloy consisting of the balance aluminum and unavoidable impurities.

The addition of Zn gives the alloy a sacrificial effect. Furthermore, it diffuses into the core material during brazing, and after brazing, at room temperature or by the artificial aging treatment described above, at the core material side interface portion near the interface between the core material and the sacrificial material, the longest diameter is 1 to 50 nm
It has an effect of forming a -Cu-Mg-Zn-based precipitate.
If the content of Si and Cu in the above core material is Zn in the sacrificial material
If the amount is less than 1.0 wt%, the effect is not sufficient and the amount is
If it exceeds 6.0% by weight, the melting point will be lowered and it will melt. Desirably, the addition of 4.0 to 5.0 wt% exerts a superior effect.

The addition of Mg enhances the strength of the sacrificial alloy, and diffuses into the core material during brazing, resulting in Al--Cu--Mg.
Along with aging precipitation of Zn, the fatigue strength of the tube itself and the entire heat exchanger is improved. If the amount is less than 0.5 wt%, Al-Cu-M is sufficient to sufficiently improve the strength.
Aged precipitation of g-Zn system does not occur. If it exceeds 3.5% by weight, the melting point will be lowered and it will melt.

Although the addition of Mn is effective in improving the strength of the alloy, if its content exceeds 1.6 wt%, the rolling workability during the production of the material will be poor and the occurrence of burrs will increase, so Mn ≦
Specified as 1.6 wt%. A more desirable amount of Mn added is 0.
The range of 5 to 1.3 wt% is good.

The addition of In and Sn also gives a sacrificial effect to the alloy. If the amount is less than 0.002 wt%, the effect is not sufficient, and if the amount exceeds 0.3 wt%, the rolling workability of the alloy deteriorates, and it becomes unsuitable as a sacrificial material used for a brazing sheet of three-layer material.

The sacrificial alloy elements of the present invention are as described above. As an unavoidable impurity, Si can be contained if it is 0.5 wt% or less, but 0.1 wt% or less is preferable. Fe
Can be contained if it is 0.8 wt% or less, preferably 0.1 wt% or less. Elements other than the above, such as Cr, Zr, and Ti, for improving strength may be contained as impurity elements as long as the content is 0.05 wt% or less.

The brazing sheet referred to in the present invention is a three-layer material having the above alloy composition, for example, a plate thickness of 0.2 mm.
In the case of, the thickness of both brazing material and sacrificial material is usually 20 to 30 μm.
It is a degree. However, the coverage varies depending on the plate thickness of the member used and is not limited to this value.

Further, the brazing method in the present invention may be a flux brazing method, a Nocolock brazing method using a non-corrosive flux, or the like. Assembling before brazing, cleaning, and flux coating depending on the case may be performed as usual. In this case, if a cesium-based flux is used as the flux, an Al-Si-Cu-Zn-based brazing material can also be used.

[0031]

EXAMPLES The present invention will be specifically described below with reference to examples.

A three-layer brazing sheet plate material having a thickness of 0.20 mm for an aluminum alloy tube material, which is a combination of a core material having the composition shown in Table 1, a brazing material having the composition shown in Table 2 and a sacrificial material, is prepared by a usual method. Manufactured. The brazing material has a clad ratio of 10% and the sacrificial material has a clad ratio of 15%. Further, Fe and Si are contained as impurity elements in the sacrificial material, respectively.
It is contained within the range of 01 to 0.2 wt%. A heat exchanger was assembled using these tube plates, a bare fin plate (JIS3003 + 1.5 wt% Zn) processed into a corrugated plate with a plate thickness of 0.08 mm, a header plate, a side plate, and a resin tank, and the flux was applied to the heat exchanger. Under the condition of N
_The heat of brazing is applied in ₂ gases, and then artificial aging treatment is performed, and core Nos. 1 to N of the radiator heat exchanger shown in FIG.
o.24 was created. Specifically, as the tube material, a coil-shaped plate material having a plate thickness of 0.2 mm shown in Tables 1 and 2 was manufactured by an ordinary method, and the coil-shaped plate material was slitted into a strip material according to the size of the electric resistance welded pipe. Using this ERW pipe manufacturing device,
It was processed into an electric resistance welded pipe with a thickness of 16.0 mm and a thickness of 1.8 mm. Also, a coil-shaped plate material having the same structure and a plate thickness of 1.0 mm was slittered to form a strip for a header. Then, the assembled radiator is coated with a 5% concentration liquid obtained by mixing 3% of cesium-based flux with potassium fluoride-based flux, and applying N
Brazing was performed by heating in _two gases under the conditions shown in Table 3.

In each of the obtained heat exchanger cores No. 1 to No. 24, a core material portion corresponding to a distance within 30 μm in the thickness direction of the clad material from the interface between the core material and the sacrificial material is provided for each tube material. It was extracted by a mechanical polishing method, micro holes (needle holes) were opened by an electrolytic etching method with a HNO ₃ methyl solution, and the core material portion in the vicinity of the hole was microscopically observed by a transmission electron microscope. And the longest diameter 1-50 nm diameter Al-Cu-
The Mg-Zn-based precipitate was observed, the sample thickness in the observation visual field was determined by interference fringes, and the number density of the present precipitate per unit volume (μm ³ ) was measured using image processing. The results are shown in Table 3.

The durability of these heat exchangers was evaluated by repeated pressure fatigue test. For test conditions, to supply coolant to the respective heat exchanger core, repeatedly performs pressurization at a period of 5Hz the supply pressure between the maximum pressure 2.4kgf / cm ² and 0 kgf / cm ^2, the tube is broken The durability was evaluated by the number of repetitions up to. If the number of repetitions exceeded 25,000, the durability was judged to be acceptable. The results are shown in Table 4.

Next, as a tube inner corrosion resistance test, Cu
Tap water containing 10 ppm of ²⁺ ions was circulated inside the core, and a cyclic corrosion test at 80 ° C. for 8 hours and room temperature for 16 hours was performed for 3 months. The pit depth generated on the surface of the sacrificial material was obtained by the depth of focus method using an optical microscope. Also,
As a tube outer corrosion resistance test, a CCT test using a 5% NaCl solution was performed. Cycle condition is spraying: 35 ℃ x
4 hours (98% RH) → drying: 60 ° C. × 2 hours (30% RH) → wetting: 50 ° C. × 2 hours (95% RH) were set as one cycle, and 150 cycles were tested. The pit depth generated on the surface of the brazing material was obtained by the depth of focus method using an optical microscope. The results are shown in Table 4.

Regarding the brazing property, the joining ratio between the tube and the fin was measured, and if it was 90% or more, it was evaluated as acceptable. Regarding melting at the time of brazing heat, visually observing after heating,
The presence or absence thereof was evaluated. The results are shown in Table 4.

[0037]

[Table 1]

[0038]

[Table 2]

[0039]

[Table 3]

[0040]

[Table 4]

From the above results, the heat exchanger cores of Comparative Examples Nos. 17, 19, and 21 have a higher aging treatment temperature after brazing heat than the heat exchanger cores of the present invention, and therefore Al-Cu-Mg. -Z
Although the n-based compound is precipitated, the number of fine precipitates (metastable phase) such as 1 to 50 nm specified in the present invention is very small (much smaller than the number density specified in the present invention), and is 0.2 μm or more. Coarse compounds will precipitate as a stable phase,
The so-called overaging phenomenon occurs, and in the durability test of the actual heat exchanger, the fatigue strength is significantly reduced and the heat exchanger is ruptured at an early stage. The heat exchanger cores of Comparative Examples No. 16, 18, and 20 are
Similar to the conventional example, since the artificial aging treatment after the brazing heat is not performed, the dramatic improvement in fatigue strength as in the present invention is not seen. Further, since the core of Comparative Example No. 22 is cooled at a faster cooling rate than the conventional example after the brazing heat is added, the durability of the core of Comparative Examples No. 23 and 24 is slightly improved (15,000). However, since the artificial aging treatment after brazing was not performed, the target number of repetitions of 25,000 could not be secured, and the durability was inferior to that of the example of the present invention. Has become.

From the above evaluation results, the heat exchanger of the present invention is
The corrosion resistance is secured at the same level as the conventional one, and the durability is dramatically improved compared to the conventional one. Therefore, there is no problem in using it as a heat exchanger for automobiles. Moreover, the heat exchanger of the present invention obtained in the above embodiment is manufactured without crushing of fins, and the manufactured radiator has excellent thermal efficiency.

[0043]

As described above, the heat exchanger of the present invention using the aluminum alloy brazing sheet of the present invention is
Fatigue strength after brazing is greatly improved, corrosion resistance is excellent, and there is no melting at the time of brazing, downsizing and weight reduction are possible, and a remarkable effect in industry is achieved.

[Brief description of drawings]

FIG. 1 is a perspective view, partly in section, showing a radiator.

FIG. 2 is a sectional view showing a structure of a brazing sheet according to the present invention.

FIG. 3 is an explanatory diagram showing a diffusion state of elements of a brazing sheet according to the present invention.

[Explanation of symbols]

1 Flat tube Two fins 3 header 4 tanks 5 core material 6 brazing material 7 sacrificial material

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI F28F 21/08 F28F 21/08 D (58) Fields investigated (Int.Cl. ⁷ , DB name) C22C 21/00-21 / 18 B23K 35/22 F28F 19 / 06,21 / 08

Claims (5)

(57) [Claims] 1. A three-layer structure aluminum alloy brazing in which an aluminum alloy brazing material is clad on one surface of an aluminum alloy core material containing at least Cu, and an aluminum alloy sacrificial material containing at least Zn and Mg is clad on the other surface. In a heat exchanger obtained by brazing using a sheet, from the interface between the sacrificial material and the core material of the brazing sheet that constitutes the heat exchanger, into the core material 30
Al-C with the longest diameter of 1 to 50 nm up to the depth of μm
A heat exchanger made of an aluminum alloy having excellent fatigue strength and corrosion resistance, in which u-Mg-Zn-based precipitates are distributed in a number of 150 / μm ³ or more. 2. The aluminum alloy brazing sheet comprises: Si: 0.2-1.5 wt%, Cu: 0.4-2.5 wt%, M:
n: 0.5 to 2.0 wt% and brazing material made of aluminum alloy is clad on one side of an aluminum alloy core material made of balance aluminum and unavoidable impurities, and Zn: 1.0 to 6.0 wt%, Mg on the other side. The aluminum alloy heat exchanger according to claim 1, which has a three-layer structure in which an aluminum alloy sacrificial material containing 0.5 to 3.5 wt% and the balance aluminum and unavoidable impurities is clad. 3. An aluminum alloy brazing sheet comprising: Si: 0.2-1.5 wt%, Cu: 0.4-2.5 wt%, M:
n: 0.5 to 2.0 wt% is contained, and further Mg: 0.03 to 0.5
wt%, Cr: 0.03 to 0.3 wt%, Zr: 0.03 to 0.3 wt%,
Ti: One or more of 0.03 to 0.3 wt% is contained, and a brazing material made of aluminum alloy is clad on one side of an aluminum alloy core material made of the balance aluminum and unavoidable impurities, and Zn is made on the other side. : 1.0 ~ 6.0wt%,
The aluminum alloy heat exchanger according to claim 1, which has a three-layer structure in which Mg: 0.5 to 3.5 wt% is contained, and an aluminum alloy sacrificial material comprising the balance aluminum and unavoidable impurities is clad. 4. The aluminum alloy brazing sheet comprises: Si: 0.2-1.5 wt%, Cu: 0.4-2.5 wt%, M:
n: 0.5 to 2.0 wt% and brazing material made of aluminum alloy is clad on one side of an aluminum alloy core material made of balance aluminum and unavoidable impurities, and Zn: 1.0 to 6.0 wt%, Mg on the other side. : 0.5-3.5wt%, In: 0.002-0.3wt%, Sn: 0.002-
3. The aluminum alloy according to claim 1, which has a three-layer structure in which one or more of 0.3 wt% and Mn: 1.6 wt% or less are contained, and an aluminum alloy sacrificial material consisting of the balance aluminum and unavoidable impurities is clad. Made heat exchanger. 5. The aluminum alloy brazing sheet comprises: Si: 0.2-1.5 wt%, Cu: 0.4-2.5 wt%, M
n: 0.5 to 2.0 wt% is contained, and further Mg: 0.03 to 0.5
wt%, Cr: 0.03 to 0.3 wt%, Zr: 0.03 to 0.3 wt%,
Ti: One or more of 0.03 to 0.3 wt% is contained, and a brazing material made of aluminum alloy is clad on one side of an aluminum alloy core material made of the balance aluminum and unavoidable impurities, and Zn is made on the other side. : 1.0 ~ 6.0wt%,
Mg: 0.5-3.5 wt% is included, and In: 0.002-
0.3 wt%, Sn: 0.002 to 0.3 wt%, Mn: 1.6 wt% or less One or two or more types are contained, and a three-layer structure in which an aluminum alloy sacrificial material consisting of the balance aluminum and unavoidable impurities is clad. The aluminum alloy heat exchanger according to claim 1.