JP2000153387A - Aluminum alloy clad for heat exchanger excellent in brazeability - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an aluminum alloy clad material for a heat exchanger which is high in flowability of a brazing filler metal, excellent in brazeability and improved in strength characteristic after brazing. SOLUTION: In an aluminum alloy clad material in which a brazing filler metal is cladded on one side or both sides of a core, the core is formed of Al-Mn alloy in which 0.5-2.0% Mn is contained as a main component and the content of Mg is regulated to be <=0.04%, and the brazing filler metal is formed of Al-Si alloy in which 6-14% Si is contained, the content of Ca is regulated to be <0.005%, and the content of Mg is regulated to be <=0.04%.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an aluminum alloy clad material for a heat exchanger having excellent brazing properties, and more particularly to a working fluid passage of an aluminum alloy heat exchanger joined by brazing, such as an evaporator or a radiator of a car air conditioner. Particularly, the present invention relates to an aluminum alloy clad material for a heat exchanger having excellent brazing properties and high strength after brazing.

[0002]

2. Description of the Related Art Aluminum alloy heat exchangers are widely used as radiators for automobiles, oil coolers, intercoolers, evaporators and condensers for heaters and air conditioners, and heat exchangers for oil coolers for hydraulic equipment and industrial machinery. The production is performed by, for example, combining a fin material with a tube material or a plate material clad with a brazing material constituting a working fluid passage and joining them by flux brazing or vacuum brazing.

[0003] Brazing using a chloride-based flux has conventionally been applied as flux brazing, but in recent years, from the viewpoints of no pollution and cost reduction, brazing using a fluoride-based flux has attracted attention. It has become the mainstream of the brazing method for aluminum alloy heat exchangers.

On the other hand, from the viewpoint of reducing the weight of automobiles, there is a strong demand for reducing the weight and cost of heat exchangers for automobiles. In order to achieve these demands, materials for heat exchangers such as working fluid passages are further reduced in thickness. Therefore, it is required that the amount of flux used in the brazing operation be reduced by further improving the brazing property of the material. In addition, brazing joining becomes difficult as the material becomes thinner, which causes a problem in the manufacturability and durability of the heat exchanger. Therefore, improvement in brazing property in fluoride flux brazing is desired.

[0005]

SUMMARY OF THE INVENTION The present invention satisfies the above-mentioned requirements in the case where the constituent material of the heat exchanger made of aluminum alloy, in particular, the working fluid passage material is brazed by using a fluoride-based flux. In order to obtain an aluminum alloy clad material, the brazing property in fluoride flux brazing, the composition of the core material on the strength characteristics after brazing, the composition of the brazing material clad on both sides thereof and the effect of their combination, The purpose of the present invention is to provide an aluminum alloy clad material for a heat exchanger, which has a high fluidity of brazing, is easy to braze, and has improved strength characteristics after brazing. Is to do.

[0006]

In order to achieve the above object, an aluminum alloy clad material for a heat exchanger having excellent brazing properties according to claim 1 of the present invention is provided by cladding a brazing material on one or both surfaces of a core material. An aluminum alloy clad material, wherein the core material contains Mn: 0.5 to 2.0% as a main component and the content of Mg is regulated to 0.04% or less.
1-Mn-based alloy, wherein the brazing material is Si: 6-14
%, The content of Ca is regulated to less than 0.005%,
It is characterized by being composed of an Al-Si alloy in which the content of g is regulated to 0.04% or less.

The aluminum alloy clad material for a heat exchanger according to claim 2 is an aluminum alloy clad material in which a brazing material is clad on one or both surfaces of a core material,
The core material is made of an aluminum alloy containing Mn: 0.5 to 2.0%, the balance being Al and impurities, and the content of Mg is regulated to 0.04% or less.
-14%, the content of Ca is regulated to less than 0.005%, and the content of Mg is regulated to 0.04% or less.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The significance of the alloy components in the aluminum alloy clad material for heat exchangers having excellent brazing properties of the present invention and the reasons for limiting the same will be described. (1) Components of the core material Mn in the core material functions to improve the strength of the core material, make the potential of the core material noble, increase the potential difference from the sacrificial anode layer, and increase the corrosion resistance. The preferred range of Mn content is 0.5 to 2.0%. If the content is less than 0.5%, the effect is small. If the content exceeds 2.0%, a coarse compound is formed at the time of casting, making the rolling process of the material difficult, and a sound material. Can not be obtained.

In brazing using a fluoride-based flux, Mg diffuses to the surface during the brazing heating process,
MgF reacts with fluorine (F), a component of flux
_Since compounds such as ₂ are generated and the amount of flux is insufficient to easily reduce the brazing property, it is necessary to regulate the content to 0.04% or less.

In order to improve the strength of the core material, increase the potential of the core material, increase the potential difference from the sacrificial anode layer, and enhance the anticorrosion effect, 0.5 to 1.5% Cu is contained in the core material. It can be contained. Zn, Cr, Zr, and the like may be contained in the core material as long as the effects of the present invention are not impaired. In addition, the characteristics of the present invention are not impaired even when impurities such as Ti, B, Si, and Fe are added to refine the ingot structure.

(2) Components of brazing filler metal Si in the brazing filler metal is an element having a function of lowering the melting point of the brazing material and increasing the fluidity of the brazing material.
It is in the range of 14%.

In the case of fluoride flux brazing, Mg is easily concentrated on the surface of the brazing material during the brazing process, and reacts with fluorine (F) as a flux component to produce MgF ₂ ,
Since the absolute amount of the flux is insufficient and the brazing property is reduced, the content is preferably regulated to 0.04% or less.

The content of Ca in the brazing material is restricted to less than 0.005% because it forms a dense oxide on the surface of the brazing material, lowering the wettability of the brazing material and the spreadability of the brazing material, and lowering the brazing performance. Is preferred.

In order to further improve the brazing properties, for example, 0.1% or less of Be, Sr, L
One or more of i and Na may be contained. Also,
Elements such as Mn, Cu, Ti, Cr, Zr, and Ni can be contained in the brazing material in small amounts within a range that does not impair the effects of the present invention, for the purpose of improving the strength of the brazing material. However, if the content of these elements increases, the self-corrosion resistance of the brazing filler metal decreases, so the total content of these metals is
It is preferred to keep it below 1%. Further, Zn, In,
Addition of Sn or the like does not impair the effects of the present invention.

The aluminum alloy clad material for a heat exchanger according to the present invention has excellent brazing properties. The aluminum alloy constituting the core material and the brazing material is formed by, for example, ingot casting by continuous casting, homogenizing treatment, or homogenizing. After the treatment, hot-rolled to a predetermined thickness, then combine the materials, according to a conventional method, hot-rolled into a clad material, finally cold-rolled to a predetermined thickness, and finally annealing It is manufactured through a process.

[0016]

Hereinafter, examples of the present invention will be described in comparison with comparative examples. Example 1 By continuous casting, an aluminum alloy for a core material having a composition shown in Table 1 (compositions shown in core materials Nos. 1 to 5) and a composition shown in Table 2 (compositions shown in brazing materials Nos. A to C) The aluminum alloy for the brazing material having ingot is ingoted, the aluminum alloy for the core material is homogenized, and then the surface is cut to a thickness of 21 mm to obtain the material for the core material. After rolling to form a brazing material having a thickness of 4.5 mm, the brazing material was overlapped on both sides of the core material and hot-rolled to obtain an aluminum alloy clad material having a thickness of 3 mm. Thereafter, cold rolling was performed and final annealing was performed to prepare a 0.5 mm thick aluminum alloy clad soft plate (temper 0) (cladding materials Nos. 1 to 7).

Comparative Example 1 By continuous casting, an aluminum alloy for a core material having the composition shown in Table 1 (the composition shown in core material Nos. 6 to 9) and the composition shown in Table 2 (the brazing material No. D to G) were used. An aluminum alloy for a brazing material having the following composition (indicated composition) was ingot, and a 0.5 mm-thick aluminum alloy clad soft plate (temper 0) was produced in the same manner as in Example 1 (cladding materials Nos. 8 to 10). 1
5).

The aluminum alloy clad materials (cladded materials Nos. 1 to 1) obtained in Example 1 and Comparative Example 1 described above.
Regarding 4), (1) strength after brazing and (2) brazing property were evaluated according to the following methods. Table 3 shows the evaluation results. (1) Strength after brazing After heating the clad material under the same conditions as the brazing conditions,
After cooling, a tensile test was performed. That is, a fluoride-based flux (concentration: 1%) is applied to the clad material, heated in a nitrogen gas atmosphere at a temperature of 600 ° C. (material temperature) for 5 minutes (fluoride-based brazing heat treatment), and then cooled. A tensile test was performed to measure the tensile strength (MPa).

(2) Brazing performance As shown in FIG. 1, an aluminum alloy clad material 2 in which a brazing material 4 or 5 is clad on both surfaces of a core material 6 has a width of 20 mm.
It was cut to a length of 40 mm, and this was cut into 3003 alloy material (width 25
mm, 40 mm in length, and 2 mm in thickness) 3) to obtain an inverted T-shaped joint 1, which was treated by the same fluoride flux brazing heat treatment method as described above. As shown in FIG. 2, fillet portions 7 and 8 are melt-formed at the corners of the inverted T-shaped joint 1 after the treatment, so that the cross-sectional areas A ₁ and A _{2 of} these fillet portions 7 and 8 are formed. And the cross-sectional areas A ₁ and A ₂ and the brazing material 4 before brazing were heated.
And the ratio of the cross-sectional areas A ₀₁ and A ₀₂ to the flow coefficient K =
Calculate (A ₁ + A ₂ ) / (A ₀₁ + A ₀₂ ). The larger the flow coefficient K, the higher the ratio of the molten brazing material, indicating that the flowability of the brazing material is good and the brazing property is excellent. In brazing a normal automotive heat exchanger brazing sheet, when the flow coefficient K is less than 0.35, a brazing defect such as a broken fillet (a portion where a fillet is not formed) tends to occur. Indicates that the brazing property is good (良好) when the flow coefficient K is 0.35 or more,
Less than 0.35 was regarded as poor brazing property (x).

[0020]

[Table 1]

[0021]

[Table 2]

[0022]

[Table 3] << Table Note >> Brazing properties ○: Flow coefficient of 0.35 or more ×: Flow coefficient of less than 0.35 or broken fillet

As can be seen from Table 3, the examples satisfying the conditions of the present invention (cladding materials Nos. 1 to 7) all have a flow coefficient K of 0.35 or more and show excellent brazing properties.
Each of the strengths after brazing exhibited an excellent strength of 107 MPa or more. In addition, all of the test materials of the examples were excellent in manufacturability without causing any problem in manufacturing.

On the other hand, the comparative examples (cladding materials Nos. 8 to 15) out of the conditions of the present invention do not have the required performance as aluminum alloy cladding materials for heat exchangers. That is, the clad material No. No. 8 has a low tensile strength because the content of Mn in the core material is small. Cladding material No.
In No. 9, since the content of Mn in the core material was too large, rolling was difficult and a sound clad material could not be produced. Cladding material No. In No. 10, since the amount of Mg in the core material was large, the brazing property was inferior, a sufficient fillet was not formed, and the fillet was broken.

The clad material No. 11, the core material is JIS3
Since it corresponds to a 003 alloy and contains a large amount of Mg, the brazing property was inferior, a sufficient fillet was not formed, and the fillet was cut. Cladding material No. 12 is S of brazing material
Since the i amount is small, the flow coefficient K is small and the brazing property is inferior.

No. In No. 13, since the content of Si in the brazing material was too large, the rollability was not sufficient, and a sound clad material could not be produced. Cladding material No. No. 14 has a high Mg content in the brazing material, and the cladding material N
o. In No. 15, since the Ca content in the brazing filler metal was large, the brazing properties were inferior, and sufficient fillets were not formed, resulting in breakage of the fillets.

[0027]

According to the present invention, in particular, there is provided an aluminum alloy clad material for a heat exchanger which has high brazing fluidity, excellent brazing properties, and improved strength characteristics after brazing. . According to the aluminum alloy clad material for the heat exchanger, the thickness of the working fluid passage material can be reduced, and the evaporator, the radiator, the condenser,
It is possible to reduce the weight and extend the life of the aluminum heat exchanger.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a state of a brazing property verification test (before brazing heating) of an aluminum alloy clad material for a heat exchanger of the present invention.

FIG. 2 is a cross-sectional view showing a state of a brazing property verification test (after brazing heating) of the aluminum alloy clad material for a heat exchanger of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Inverted T-shaped joint 2 Aluminum alloy clad material 3 3003 alloy material 4, 5 Brazing material 6 Core material 7, 8 Fillet part

Claims (2)

[Claims] 1. An aluminum alloy clad material in which a brazing material is clad on one or both surfaces of a core material, wherein the core material contains Mn: 0.5 to 2.0% (% by weight, the same applies hereinafter) as a main component, A with Mg content restricted to 0.04% or less
1-Mn-based alloy, wherein the brazing material is Si: 6-14
%, The content of Ca is regulated to less than 0.005%,
An aluminum alloy clad material for a heat exchanger having excellent brazing properties, comprising an Al-Si alloy in which the content of g is controlled to 0.04% or less. 2. An aluminum alloy clad material in which a brazing material is clad on one or both surfaces of a core material, wherein the core material contains 0.5 to 2.0% of Mn, the balance being Al and impurities, and the content of Mg. The brazing material contains Si: 6 to 14%, the Ca content is controlled to less than 0.005%, and the Mg content is controlled to 0.04% or less. An aluminum alloy clad material for a heat exchanger having excellent brazing properties, which is made of a regulated Al-Si-based aluminum alloy.