JPH08104936A - Aluminum alloy clad fin material for heat exchanger - Google Patents

Abstract

PURPOSE: To produce an Al alloy clad fin material excellent in strength after brazing and sacrificial anode effect to a tube by cladding the core material of an Al alloy contg. Mn, Zn, Fe, Si or the like with the brazing filler metal of an Al alloy contg. Zn and Cu. CONSTITUTION: Both sides of an Al alloy core material contg., by mass, 0.4 to 2.0% Mn, 0.5 to 2.5% Zn and 0.3 to 2.0% Fe+Si, furthermore contg. one or more kinds of 0.05 to O.3% Cr and 0.05 to O.3% Zr, and the balance Al with inevitable impurities are clad with the brazing filler metal of an At alloy having a compsn. contg. 6.0 to 15.0% Si, 1.0 to 8.0% Zn and 0.5 to <5.0% Cu, and the balance Al with inevitable impurities, and in which the containing ratio of Zn to Cu, i.e., Zn/Cu is regulated to 0.5 to 3.0. The brazing filler metal is incorporated with 0.01 to 0.4%. Bi according to necessary. This Al alloy fin material for a heat exchanger is excellent in strength after brazing and sacrificial anode effect to a tube.

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 fin material for a heat exchanger, and in particular, when a heat exchanger for an automobile made of an aluminum alloy is manufactured by brazing, it is suitable as a fin material which is a constituent material of the aluminum alloy. It relates to an alloy clad fin material.

[0002]

2. Description of the Related Art Aluminum alloy heat exchangers such as radiators, heater cores, oil coolers, intercoolers, car air conditioner condensers and evaporator heat exchangers for automobiles are made of Al--Cu or Al--Mn.
It is manufactured by vacuum brazing or flux brazing a working fluid passage forming material made of an aluminum alloy such as Al-Mn-Cu-based and a fin material made of an aluminum alloy. The brazing material necessary for brazing may be arranged on the passage component side or the fin material side. In the latter case, as the fin material,
A composite material in which an aluminum alloy is used as a core material and both surfaces thereof are clad with an Al—Si alloy brazing material as a skin material is used.

The fin material is required to have a sacrificial anode effect in order to prevent corrosion of the material forming the passage of the working fluid, and it is also possible to prevent the fin material from being deformed due to high temperature heating during brazing and from eroding the brazing material. In order to prevent deformation at the time of brazing and erosion of the braze, Mn is effectively added to the aluminum alloy. Al-Mn alloys such as 3003 alloy and 3203 alloy are applied.

Further, in order to give a sacrificial anode effect to this Al-Mn alloy, it has been attempted to add Zn, Sn, In, etc. (Japanese Patent Publication No. 56-12395), Cr, T.
It has been proposed to further improve the high temperature buckling resistance by adding i, Zr and the like. (Japanese Patent Publication Sho 67-13787
(Gazette etc.)

On the other hand, as the brazing material in the aluminum alloy clad fin material, the Al--Si type brazing material is used as described above, and BA4343 defined in JIS Z 3263 is used.
Alloy (Al-7.5% Si alloy), BA4045 alloy (Al-10% Si alloy)
, BA4047 (Al-12% Si alloy) or other Al-Si brazing filler metal is used as a clad fin material with a chloride-based flux or in a non-active atmosphere with a fluoride-based flux. Used in flux brazing of alloy heat exchangers.

[0006] The solidus temperature of the Al-Si alloy brazing material specified in JIS is 577 ° C, and the liquidus temperature is 580-615.
However, the brazing work is generally performed at a temperature of between 590 and 600 ° C. between the solidus temperature and the liquidus temperature, but in recent years, weight reduction in heat exchangers, especially in automobile heat exchangers, Due to demands such as cost reduction, the constituent materials of heat exchangers are becoming thinner and thinner, and when the thinned aluminum alloy fin material is heated to the above brazing work temperature, deformation easily occurs, Since the strength after brazing is reduced, there is a problem that the fin falls down.

The high brazing temperature is close to the melting temperature (solidus temperature) of tubes, plates, and other aluminum members to be brazed, and local melting occurs during brazing, causing the shape to collapse and brazing. There is also a risk of failure. Particularly, this problem is likely to occur in a fin material or a 7000 series aluminum alloy in which Cu, Mg or the like is added to the Al—Mn alloy used as the core material of the clad fin material to increase the strength.

In order to solve such problems and also from the viewpoint of energy saving, low melting point brazing filler metals having a melting point lower than that of 580 ° C. are required, and various aluminum alloy brazing filler metals have been developed and proposed. There is. For example, A
BA4145 alloy (Al-10% Si) in which Cu is added to 1-Si alloy
-4% Cu), Zn, Cu added BA4245 alloy (Al-10% Si
-10% Zn-4% Cu) has been developed. However, 41
The 45 alloy has a problem in corrosion resistance, and the 4245 alloy has poor workability and it is often difficult to obtain the shape of a plate material.

Al6.0-5.0% Si alloy with Zn6.0-
Contains 15.0% and a small amount of Be or Be and B
Aluminum alloy brazing material to which i is added (Japanese Patent Laid-Open No. 2-251394
Gazette), Al-8.0 to 15.0% Si-6.0 to 15.0% Zn
-5.0 to 15.0% Cu alloy brazing material (JP-A-3-57588), Al-4 to 12% Si-15 to 55% Zn-0.2 to 2.0
% Cu alloy brazing material (Japanese Patent Laid-Open No. 3-230890) has also been proposed, but since these aluminum alloy brazing materials contain a large amount of Zn, the spontaneous potential of the brazing part becomes extremely base. In addition, the brazing part is likely to be corroded preferentially, and the inclusion of a large amount of Cu lowers the self-corrosion resistance of the brazing material, and the natural electrode potential of the brazing part becomes extremely noble.
This causes a problem in the corrosion resistance of the joint, such that the aluminum alloy as the base material such as the passage forming material to be joined is preferentially corroded.

Si: 5-15%, Zn: 0.5-8%, Cu: 0.1
An aluminum alloy brazing material containing 1% by weight and the balance of Al and unavoidable impurities is also proposed (JP-A-6-182582 and JP-A-6-184686).
. This brazing material has a low melting point and relatively excellent corrosion resistance, but depending on the corrosive environment, the natural potential becomes base and the brazing part may be preferentially corroded.

On the other hand, the fin material is required to have excellent high-temperature buckling resistance and sacrificial anode effect as described above in order to prevent deformation and strength decrease during high temperature heating brazing and to prevent corrosion of the passage constituting material. In addition, the fin material is required to have sufficient strength and self-corrosion resistance so that the brazed aluminum heat exchanger can withstand long-term use in various environments. Especially when exposed to extremely harsh environments such as heat exchangers for automobiles, after brazing and joining, the fins and their peripheral members have sufficiently excellent strength characteristics and self-corrosion resistance as heat exchanger constituent members. In order to provide the above, the combination of the aluminum alloy core material and the brazing material forming the aluminum alloy clad fin material is extremely important.

[0012]

SUMMARY OF THE INVENTION The present invention relates to an aluminum alloy brazing material as a skin material for an aluminum alloy clad fin material for a heat exchanger used when an aluminum alloy heat exchanger is manufactured by brazing. As a result of conducting a multi-faceted study in order to solve the problem of No. 1 and to find a combination of the core material and the brazing filler metal that can sufficiently withstand the harsh usage environment after the brazing and joining. The purpose is to have good brazing property, low melting point, and can perform brazing work at a temperature of 580 ° C or less, excellent workability, and easily processed into the shape of plate material or brazing sheet. The aluminum alloy base material such as the brazing part and the passage forming material to be brazed is not corroded preferentially, and the sacrifice to the tube is possible. An object of the present invention is to provide an aluminum alloy clad fin material for a heat exchanger, which also has an excellent anode effect.

[0013]

The aluminum alloy clad fin material for a heat exchanger according to the present invention for achieving the above object contains Mn: 0.4 to 2.0% and Zn: 0.5 to 2.5%, and contains Si and Fe. On the both sides of the aluminum alloy core material containing 0.3 to 2.0% in total, and further containing at least one of Cr: 0.05 to 0.3% and Zr: 0.05 to 0.3%, with the balance being Al and inevitable impurities. , Si: 6.0-15.0%,
Zn: 1.0-8.0%, Cu: 0.5% or more and less than 5.0%, the balance consisting of Al and inevitable impurities, Zn and Cu
The first feature of the construction is that an aluminum alloy brazing material having a content ratio of Zn / Cu: 0.5 to 3.0 is clad, and the aluminum alloy brazing material further comprises Bi: 0.01.
The second feature of the invention is that it contains 4%.

Explaining the meaning and content range of the components contained in the aluminum alloy brazing material constituting the skin material of the aluminum alloy clad fin material of the present invention, Si has the effect of lowering the melting point of the brazing material and increasing the fluidity of the brazing material. Have. The preferred content range is 6.0 to 15.0%, and 6.
If it is less than 0%, the effect is not sufficient, and if it exceeds 15.0%, the melting point of the brazing material becomes high, and the workability at the time of manufacturing the brazing material also deteriorates. The more preferable content range of Si is 7.0
~ 13.0%.

Similar to Si, Zn has the effect of lowering the melting point of the brazing material. The preferred content range is 1.0 to 8.0%
The effect is small when less than 1.0% is added.
If it exceeds%, the workability at the time of manufacturing the brazing material becomes poor, and the spontaneous potential becomes remarkably base, which deteriorates the corrosion resistance of the brazed part. The more preferable content range of Zn is 1.0 to
It is 5.0%.

Cu, together with Zn, has the effect of lowering the melting point of the brazing material. The preferred content is 0.5% or more 5.0
%, The effect is not sufficient if it is less than 0.5%, and if it is more than 5.0%, the workability at the time of manufacturing the brazing material deteriorates, and the spontaneous potential becomes extremely noble. Corrosion resistance of the base material deteriorates and self-corrosion also increases. The content is more preferably in the range of more than 1.0% and 4.0% or less, and further preferably in the range of 2.0 to 4.0%.

Bi, which is added as a selective component, has the effect of lowering the melting point of the brazing material and improving the wettability and fluidity of the brazing material. The preferred addition range is 0.01-0.4%, 0.01
If it is added in an amount of less than 0.4%, its effect is small, and if it is added in an amount of more than 0.4%, the workability at the time of manufacturing the brazing material is lowered and the corrosion resistance is impaired. The effect of improving wettability and fluidity is saturated. The more preferable addition range of Bi is 0.01 to 0.2%.

In the brazing material of the present invention, Zn, which makes the natural potential base, and Cu, which makes the potential noble, are added in combination and the potential is kept within an appropriate range to improve the self-corrosion resistance of the brazing material. , Which provides excellent corrosion resistance to the brazed part. For this reason, the content ratio of Zn and Cu,
It is important to control the Zn% / Cu% ratio within a predetermined range. The preferable Zn / Cu ratio is in the range of 0.5 to 3.0. When the ratio is less than 0.5, the Cu content is high, so the potential becomes noble and the corrosion resistance becomes insufficient. When the ratio exceeds 3.0, the Zn content is high. If it becomes too much, the potential becomes base and the corrosion resistance deteriorates. A more preferable range of the Zn / Cu ratio is 1.0 to 2.5.

The aluminum alloy brazing material of the present invention contains F
e, Ti, Cr, Mn, Mg, Sr, Be, In, S
Elements such as n, Ga, Pb, Li, Ca, and Na are used to make the potential of the brazing material base and give a sacrificial anode effect, so that the structure is refined to improve the fluidity, and corrosion resistance and strength are improved. It may be added in a small amount for the purpose of, for example, and within a range that does not impair the effects of the present invention. However, if Fe is contained in a large amount, the corrosion resistance is impaired, so it is preferable to keep it to 0.8% or less.

The composition of the aluminum alloy that constitutes the core material of the clad fin material in the present invention will be described.
Mn has the effect of improving the strength of the clad material. The preferable content range is 0.4 to 2.0%, and if it is less than 0.4%, its effect is not sufficient, and if it exceeds 2.0%, coarse crystallized substances are generated during casting and workability is deteriorated, and it becomes difficult to manufacture a plate material. easy. The more preferable content range of Mn is 0.6 to 1.
6%.

Zn has the effect of making the natural potential base and enhancing the sacrificial anode effect. The preferred content range is 0.5 to 2.5
%, The effect is not sufficient if less than 0.5%, 2.5
If it is contained in excess of%, the self-corrosion property increases. The more preferable content range of Zn is 1.0 to 2.0%.

Cr and Zr have the effect of improving the high temperature buckling resistance of the aluminum alloy for core material. The preferred content range is 0.05 to 0.3%, respectively.
If it is added in an amount of less than 0.1%, its effect is small, and if it is added in an amount of more than 0.3%, coarse crystallized substances are formed during casting, which makes it difficult to produce a plate material. A more preferable content range of Cr and Zr is 0.1 to 0.2%.

Both Si and Fe give an additional effect to the effect of Mn, and have a synergistic effect of improving the strength of the cladding material together with Mn. Si and Fe are preferably contained in a total amount of 0.3 to 2.0%,
If it is less than 0.3%, its effect is small, and if it exceeds 2.0%,
Since the crystal grain size becomes small, the molten braze easily diffuses into the core material, the high temperature buckling resistance deteriorates, and the self-corrosion property also increases. A more preferable range of the total amount of Si and Fe is 0.
3 to 1.5%.

The aluminum alloy clad fin material of the present invention exhibits strength and self-corrosion resistance in the combination of the core material having the above composition and the aluminum alloy brazing material having the above composition, and is particularly contained in the brazing material. Cu
Diffuses into the core material during brazing and heating, and further improves the material strength. The core material is made of Mg, Cu, Ti, In,
Material properties can be improved by adding elements such as Sn, Ga, Pb, and Li in a range that does not impair the effects of the present invention. However, when brazing using a fluoride-based flux, Mg reacts with the flux to reduce the brazing property, so it is preferable to limit the content to 0.5% or less. Further, Cu makes the natural potential noble and reduces the sacrificial anode effect, so it is preferable to limit it to 0.5% or less.

The aluminum alloy clad material fin material of the present invention is obtained by melting and casting an aluminum alloy for brazing material and an aluminum alloy for core material by, for example, a usual method,
Produced by homogenizing, hot rolling, cold rolling, annealing treatment, plate material, and rolling by combining these aluminum alloy plate materials into fin shape of aluminum heat exchanger such as automobile heat exchanger. Molded and processed.

[0026]

In the present invention, the Al-Si type brazing material contains a predetermined amount of Zn and Cu, so that the melting point of the brazing material is lowered and the workability at the time of manufacturing the brazing material is ensured.
An aluminum alloy brazing material having improved self-corrosion resistance by controlling the content ratio of Zn and Cu in a specific range to keep the natural potential in an optimum range, giving excellent corrosion resistance to the brazing part and the base metal, and this aluminum alloy brazing material. When used as a fin material of a heat exchanger by clad with an aluminum alloy core material of a specific composition that gives good strength and sacrificial anode effect in combination with the material, it can sufficiently withstand harsh usage environment after brazing It has characteristics.

[0027]

Hereinafter, examples of the present invention will be described in comparison with comparative examples. Example 1 An aluminum alloy for a brazing material having the chemical composition shown in Table 1 and an aluminum alloy for a core material having the chemical composition shown in Table 2 were melted and cast by an ordinary method. The ingot of the aluminum alloy for the core material is homogenized, and the aluminum alloy plate for the brazing material that has been previously homogenized-hot rolled is combined and hot-rolled, and further cold-rolled, intermediate-annealed and After finishing cold rolling, an aluminum alloy clad fin material having a thickness of 0.13 mm and a brazing material clad ratio of 10% on both sides was produced.

[0028]

[Table 1]

[0029]

[Table 2]

The obtained clad fin material was cut into a width of 10 mm and a length of 35 mm, and as shown in FIG. 1, a clad fin material 2 composed of brazing materials 4 and 5 and a core material 6 was used as a 3003 alloy plate material (
(Thickness 1mm, width 25mm, length 40mm) 3), put it on the inverted T-shaped joint 1, apply fluoride flux, and then braze at 580 ° C for 10 minutes in a nitrogen gas atmosphere furnace. I went.

After heating by brazing, as shown in FIG.
The cross-sectional areas A ₁ and A ₂ of the fillet portions 7 and 8 formed by melting at the corners of the V-shaped joint were measured, and flow was obtained from the ratio to the cross-sectional area (A ₀₁ + A ₀₂ ) of the brazing material before brazing and heating. The coefficient K (flow coefficient K = (A ₁ + A ₂ ) / (A ₀₁ + A ₀₂ )) was measured. The larger the flow coefficient K, the larger the proportion of the brazing material melted, the better the fluidity of the brazing material, and the better the brazing property.

Further, the clad fin material 2 is corrugated, and as shown in FIGS. 3 and 4, the corrugated fin material 9 is converted into a multi-hole flat extruded tube (material: Al-0.3% Mn-
0.1% Cu, thickness 0.4mm) 10 are combined and a fluoride flux is applied, then 580 in a nitrogen atmosphere furnace.
Brazing heating was performed at 10 ° C for 10 minutes. The obtained brazed assembly test piece was subjected to a CASS test for 4 weeks (JIS D 020
By performing 1), the maximum corrosion depth of the tube 10 at the fin joint was measured, and the self-corrosion state of the fin material was observed.

After brazing and heating the clad plate material, a tensile test is conducted to evaluate the strength of the clad material, and the clad fin material 2 is set on a fixing jig 11 as shown in FIG. (580 ° C. × 10 minutes), and the sag sag amount (S) after heating was measured to evaluate the high temperature buckling resistance (sag resistance) of the fin material. In addition, in FIG. 5, the test piece length (a) is 120 mm and the test length (b) is 60 mm.
And

Table 3 shows the fluidity, sag resistance, tensile strength, corrosion resistance, and workability of the clad fin material in the rolled production for each test material. As shown in Table 3, all of the test materials No. 1 to No. 6 according to the present invention have good workability with almost no defects such as ear cracks at the plate end during the production of the clad plate material, By brazing at a temperature of 580 ℃, which is 10 to 20 ℃ lower, the coefficient of flow K is 0.3.
The above excellent brazing properties were obtained, and the sag resistance was a good value of 25 mm or less. Also, the strength and the corrosion resistance of the brazed joint are good. It was confirmed that the brazing property with a fluidity coefficient of 0.3 or more was achieved even when the brazing operation was performed at a temperature of 575 ° C.

[0035]

[Table 3]

Comparative Example 1 An ingot of a brazing aluminum alloy having the chemical composition shown in Table 4 and a core aluminum alloy having the chemical composition shown in Table 5 was treated according to the same process as in Example 1,
As in Example 1, the thickness is 0.13 mm and the brazing material clad ratio is on both sides.
A 10% clad plate material was produced. This clad plate material was evaluated for brazing property, high temperature buckling resistance, strength, corrosion resistance and workability during fin material production in the same manner as in Example 1. The results are shown in Table 6. In Tables 4 and 5, those outside the conditions of the present invention are underlined.

[0037]

[Table 4]

[0038]

[Table 5]

[0039]

[Table 6]

As shown in Table 6, the test material No. 7 has a small amount of Si in the brazing material and thus has a small flow coefficient and poor brazing property, and the brazing material does not contain Cu and has poor strength. . Since the brazing material (4245 alloy) contained a large amount of Zn in the test material No. 8, and the test material No. 9 contained Cu and Bi in the brazing material exceeding the upper limits of the present invention, the clad material was manufactured. At times, cracks occurred and it was not possible to obtain a sound clad fin material plate. In the test material No. 10, the Zn / Cu ratio of the brazing material was small, and the potential of the brazing material was extremely noble. Therefore, the sacrificial anode effect was inferior and a through hole was formed in the tube material.

Since the Zn / Cu ratio of the test material No. 11 exceeds the range of the present invention, the potential of the brazing material becomes remarkably base and self-corrosion of the fin material increases. Test material No. 12 had too much Si content in the brazing material, test material No. 14 had too much Mn in the core material, and test material No. 19 had too much Cr and Zr content in the core material. The workability at the time of manufacturing the brazing material was poor, and a sound clad fin material plate could not be manufactured. Test material No.1
No. 3 has a small amount of Mn in the core material, so the strength of the clad material is not sufficient. Since the core material does not contain Cr and Zr, the sag resistance is poor. The wear due to self-corrosion of is remarkable.

In the test material No. 15, the total amount of Si and Fe in the core material is too small, so that the strength of the clad fin material is inferior. Since the total content of Si and Fe in the core material of Test Material No. 16 is large, the crystal grain size of the core material becomes fine and the molten brazing material is likely to erode into the core material. Therefore, the flow coefficient becomes low, the sag drooping property becomes large, and the wear due to self-corrosion becomes remarkable. In the test material No. 17, since the Zn content of the core material is small, the spontaneous potential of the fin material is not sufficiently base, the sacrificial anode effect is inferior, and deep pitting corrosion occurs in the tube in the CASS test. Test material No. 18 has a large amount of sag and a poor high temperature buckling resistance because the core material has a low Cr content.

[0043]

As described above, according to the present invention, it is possible to perform the brazing operation at a temperature 10 to 20 ° C. lower than the conventional one,
Provided is an aluminum alloy clad fin material which is excellent in workability during manufacturing, has excellent sag resistance during heating for brazing, has excellent strength after brazing, and has an excellent sacrificial anode effect on a tube. INDUSTRIAL APPLICABILITY The clad fin material of the present invention can withstand use in a harsh environment as a constituent material of a heat exchanger, can be thinned, and can contribute to weight reduction and cost reduction of the heat exchanger. .

[Brief description of drawings]

FIG. 1 is an inverse T used in a brazing test in the present invention.
It is a sectional view showing arrangement of a character type joint and a test clad material.

FIG. 2 is a cross-sectional view after heating for brazing in FIG.

FIG. 3 is a side view showing a test piece used in a corrosion test in the present invention.

FIG. 4 is a front view of FIG. 3;

FIG. 5 is a sectional view showing an outline of a sag resistance test in the present invention.

[Explanation of symbols]

 1 Inverse T-shaped joint 2 Clad material 3 3003 Alloy plate material 4 Brazing material 5 Brazing material 6 Core material 7 Fillet part 8 Fillet part 9 Corrugated fin 10 Multi-hole flat extrusion tube 11 Fixing jig

Claims (2)

[Claims] 1. Mn: 0.4 to 2.0% (mass%, the same applies hereinafter) and Zn: 0.5 to 2.5% are contained, and Fe and Si are contained in total.
0.3 to 2.0%, Cr: 0.05 to 0.3% and Zr: 0.05 to 0.3%, and the balance A
on both sides of the aluminum alloy core material consisting of 1 and unavoidable impurities, Si: 6.0-15.0%, Zn: 1.0-8.0%, Cu: 0.5
% To less than 5.0%, the balance consisting of Al and inevitable impurities, and the content ratio of Zn and Cu is Zn / Cu: 0.5-3.
An aluminum alloy clad fin material for a heat exchanger, which is obtained by clad with an aluminum alloy brazing material of 0. 2. An aluminum alloy brazing material further comprising B
The aluminum alloy clad fin material for a heat exchanger according to claim 1, wherein i: 0.01 to 0.4% is contained.