JPH0718358A - High strength aluminum alloy fin material for heat exchanger - Google Patents

Abstract

PURPOSE:To produce an aluminum alloy fin material excellent in brazability and excellent in strength after brazing, thermal conductivity and sacrificial anodic effect to enable the thinning of a fin. CONSTITUTION:The compsn. of the fin material is constituted of a one contg. >1.5 to 2.2% Mn, 0.5 to 1.2% Si, 0.1 to 0.6% Fe and 0.5 to 2.0% Zn, in which Mg as impurities is limited to <=0.02%, and the balance Al with inevitable impurities. Cu may be incorporated by <=0.3%, and one or two kinds of <=0.25% Zr and <=0.25% Cr may selectively be added.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high-strength aluminum alloy fin material for a heat exchanger, and more specifically, a heat exchanger such as a radiator or a car air conditioner in which fins and working fluid passage constituent materials are joined by brazing. Aluminum alloy fin material used for aluminum alloy, especially high strength aluminum alloy fin material for heat exchangers, which has excellent brazing properties in fluoride flux brazing, high thermal conductivity and strength after brazing, and excellent sacrificial anode effect Regarding

[0002]

2. Description of the Related Art Heat exchangers for automobile radiators, air conditioners, intercoolers, oil coolers, etc.
It is assembled by brazing an Al-Mn-based alloy fin with a working fluid constituent material such as a Cu-based alloy, an Al-Mn-based alloy, or an Al-Mn-Cu-based alloy.
The fin material is required to have a sacrificial anode effect in order to prevent corrosion of the working fluid constituent materials, and also has excellent high temperature buckling resistance so that the fin material does not deform due to high temperature heating during brazing or the brazing material does not penetrate. Required.

Al-Mn type aluminum alloys such as JIS 3003 and JIS 3203 are used as fin materials because
This is because it effectively acts to prevent deformation during brazing and erosion of brazing. In order to give a sacrificial anode effect to the Al—Mn alloy fin material, Zn, Sn, I is added to this alloy.
A method of adding n or the like to make it electrochemically base (Japanese Patent Laid-Open No. Sho 62-62)
In order to further improve the high temperature buckling resistance (high temperature sag resistance), there is a method of adding Cr, Ti, Zr, etc. to an Al-Mn alloy (Japanese Patent Laid-Open No. 1
18919 publication).

However, in recent years, there has been an increasing demand for weight reduction and cost reduction of heat exchangers.
It has become necessary to further reduce the thickness of heat exchanger constituent materials such as fin materials.For example, if the fins are made thinner, the heat transfer cross-sectional area becomes smaller and the heat exchange performance deteriorates. Since problems occur in the strength and durability of the exchanger, further improvement in heat transfer performance and strength after brazing is desired.

The conventional Al-Mn-based alloy has a problem that the thermal conductivity is lowered because Mn forms a solid solution by heating during brazing. As a fin material that solves this difficulty, the Mn content is limited to 0.8% or less, and Zr 0.02 to 0.2
% And Si 0.1-0.8% aluminum alloys have been proposed. (Japanese Patent Laid-Open No. 63-23260) Although this alloy has improved thermal conductivity, its strength after brazing is insufficient due to the small amount of Mn, and fin collapse and deformation occur during use as a heat exchanger. There is a drawback that the sacrificial anode effect is small because it is easy and the potential is not sufficiently base.

Mn 0.01-0.3%, Zr 0.01-0.4% 1
Containing two or more species, Si0.03-0.3%, Fe0.05-
An aluminum alloy for fins containing 0.6% has been proposed (Japanese Patent Laid-Open No. 63-45352), but this alloy also has a small sacrificial anode effect because the potential is not sufficiently base. In addition, pure aluminum with high thermal conductivity (JIS 1050, 1070, etc.)
Incorporating n and In to give a sacrificial anode effect, C
Attempts have been made to improve the high temperature buckling resistance by adding r, Ti, Zr, etc., but these alloys also have excellent heat transfer performance, but their strength after brazing is not always sufficient.

As a fin material having improved strength after brazing, Al, Mn, Si, Mg, and Fe based alloys containing In and Zn are used.
Aluminum alloys with addition of Ga and Sn, and aluminum alloys with addition of Ga, Sn, etc. have also been developed (JP-A-2-248704).
Japanese Patent Laid-Open No. 3-20436), it is possible to reduce the wall thickness to some extent, but it has not yet fully satisfied the recent demand for thinning the fin material. Further, in recent years, in the case of applying brazing using a fluoride-based flux, which has been attracting attention from the viewpoint of pollution-free and low cost, and is becoming popular,
Since the alloy material containing Mg is inferior in brazing property, there is a drawback that the fin bonding rate is lowered and a problem occurs in heat transfer characteristics as a heat exchanger.

[0008]

DISCLOSURE OF THE INVENTION The present invention aims to develop an aluminum alloy fin material satisfying the requirements for thinning the fin material for heat exchangers, in order to develop strength characteristics, heat transfer performance, sacrificial anode effect and brazing property. It was made as a result of a multi-faceted examination of the effects of alloying components on, the effect of the combination of alloying components, the purpose of which is to have high strength and thermal conductivity after brazing, excellent sacrificial anode effect, It is an object of the present invention to provide a high-strength aluminum alloy fin material for a heat exchanger, which has good brazing property, particularly in brazing using a fluoride-based flux.

[0009]

A high-strength aluminum alloy fin material for a heat exchanger according to the present invention for achieving the above-mentioned object has a Mn content of more than 1.5% (mass%, the same applies hereinafter) and 2.2% or less. 5 to 1.2%, Fe0.1 to 0.6%, Zn0.5 to
The basic feature of the present invention is that it contains 2.0%, Mg is limited to 0.02% or less as an impurity, and the balance is Al and inevitable impurities. Mn is more than 1.5% and 2.2% or less.
i0.5-1.2%, Fe0.1-0.6%, Zn0.5-2.0%
1% of Zr 0.25% or less and Cr 0.25% or less
The second feature of the present invention is that the Mg content is limited to 0.02% or less, and the balance is Al and unavoidable impurities. 5 to 1.2%, Fe0.1 to 0.6%, Zn0.5 to
2.0%, Cu less than 0.3%, Mg as an impurity
It is limited to 0.02% or less, the balance consists of Al and unavoidable impurities, and more than Mn1.5% and 2.2% or less, Si0.5
~ 1.2%, Fe0.1-0.6%, Zn0.5-2.0%, Cu
0.3% or less, Zr0.25% or less, Cr0.25
% Or less, and contains Mg as an impurity of 0.1.
The second and third features of the invention are that the content is limited to 02% or less and the balance is Al and inevitable impurities.

Explaining the meaning of the alloy components and the reason for limitation in the high strength aluminum alloy fin material for heat exchangers of the present invention, Mn coexists with Si to form an Al-Mn-Si-based compound, which will be a wax. The strength of the alloy material before and after brazing is improved, and the high temperature buckling resistance and the formability are improved. If Mn is less than 1.5%, the effect is not sufficient, and if it exceeds 2.2%, coarse crystallized substances are generated during casting of the alloy, which makes it difficult to manufacture a plate material, and the amount of Mn solid solution increases to increase the thermal conductivity. descend. Therefore, the preferable content range is more than 1.5% and 2.2% or less.

Si coexists with Mn and is Al-Mn-Si.
Generate a compound of the system to improve the strength and Mn
The amount of solid solution is reduced to improve the thermal conductivity. If the Si content is less than 0.5%, the effect is not sufficient, and if it exceeds 1.2%, the fin material may melt during brazing. Therefore, the preferable content range is 0.5 to 1.2%.
Fe reduces the solid solution amount of Mn and improves the thermal conductivity. If the content is less than 0.1%, the effect is small, 0.6%
If it exceeds the range, coarse Al-Mn-Fe-based crystallized substances are generated during casting, and it becomes difficult to process the plate material. Therefore, the preferable content range is 0.1 to 0.6%.

Zn makes the potential of the fin material base and gives a sacrificial anode effect. If the content is less than 0.5%, the effect is not sufficient, and if it exceeds 2.0%, the self-corrosion property of the material deteriorates, which is not preferable. Therefore, the preferred content is 0.5-2.0%
And Cu serves to improve the strength of the fin material, but if the content exceeds 0.3%, the potential of the fin material becomes noble and the sacrificial anode effect may be impaired. Therefore, the content is limited to 0.3% or less. Zr and Cr effectively act to improve the buckling resistance of the alloy material, but both are 0.25%
If it exceeds, the thermal conductivity after brazing decreases. Therefore,
In both cases, the upper limit is 0.25%.

[0013] Mg has an effect on brazing property and its content is 0.
If it exceeds 02%, the brazing property may be impaired. Particularly in the case of fluoride-based flux brazing, fluorine (F), which is a component of the flux, easily reacts with Mg in the alloy, and a compound such as MgF ₂ is produced, which effectively acts during brazing. Insufficient amount of flux to be used causes brazing failure. Therefore, it is preferable to limit the content of Mg to 0.02% or less.

The aluminum alloy fin material of the present invention is formed into an ingot according to a usual melting and casting method, and after homogenization treatment,
It is manufactured through hot rolling, cold rolling, intermediate annealing and finish cold rolling, and usually has a thickness of 0.1 mm or less. This plate material is slit to a predetermined width, then corrugated, and alternately laminated with a flat tube for a working fluid passage made of a brazing material, such as 3003 alloy, and brazed to form a heat exchanger unit. .

[0015]

According to the constitution of the present invention, the coexistence of Mn and Si produces an Al-Mn-Si-based compound, and F
By adding e, the solid solution amount of Mn is decreased,
By making the electric potential of the material base, the interaction between these alloying elements enhances the strength and thermal conductivity after brazing and makes the sacrificial anode effect excellent. Also, M
By limiting the g content, the reaction between Mg and the flux is prevented, and the ratio of the flux that effectively acts in brazing is increased to improve the fin joint rate, and the heat exchanger has excellent heat transfer performance and durability. be able to.

[0016]

EXAMPLES Examples of the present invention will be described below in comparison with comparative examples. Example 1 An aluminum alloy ingot having the composition shown in Table 1 was homogenized, hot-rolled, cold-rolled, intermediate-annealed and finish cold-rolled according to a conventional method to obtain a fin material having a thickness of 0.07 mm. The intermediate annealing temperature was 300 ° C. After applying a fluoride flux (concentration: 1%) to the obtained fin material, heat it at 600 ° C for 3 minutes in a nitrogen gas atmosphere for 3 minutes as in the brazing condition, and then perform a tensile test on the test material after heating. I went.

The thermal conductivity of the test material after heating was evaluated by measuring the electrical conductivity at 25 ° C. In the fin material of the present invention, like the general metal material, there is a proportional relationship between the thermal conductivity and the electrical conductivity, and it is known that the thermal conductivity can be evaluated by measuring the electrical conductivity. . Furthermore, in order to evaluate the sacrificial anode effect,
After immersing in a 3% NaCl aqueous solution adjusted to pH 3 for 8 hours, the natural electrode potential was measured.

Next, the fin material is corrugated and placed on a 0.6 mm thick plate material having 3003 alloy as the core material and 4045 alloy as the skin material (brazing material), and the fluoride flux brazing material is used. After the brazing, the ratio of the corrugated fin material and the plate material brazed and joined is checked, and the brazing property is evaluated from the fin joint rate. The CASS test is performed on the joint portion of the fin and plate based on JIS D0201. It was carried out for a month, and the maximum corrosion depth of the plate was measured and the fin corrosion condition was observed. The rate of change in fin height before and after brazing was measured to evaluate the high temperature buckling resistance of the fins. Table 2 shows the test, measurement, and evaluation results.

[0019]

[Table 1]

[0020]

[Table 2] << Table Note >> High temperature buckling resistance evaluation: ◎ when the fin height change rate before and after brazing is 2.5% or less, ○ when 2.5 to 5%

As shown in Table 2, the test materials No. 1 to No. 17 according to the present invention all have excellent tensile strength (hereinafter simply referred to as tensile strength) corresponding to 130 MPa or more after brazing. , The electrical conductivity of conventional JIS 3004 fin material is 39% IA
The electrical conductivity was 43% IACS or more, while the thermal conductivity was good, in contrast to CS. Moreover, it was shown that the fin bonding rate was 95% or more and the brazing property was excellent. The natural electrode potential is also in the range of -780 to -840 mV vs SCE,
It is electrochemically noble, and the maximum corrosion depth after the CASS test is 0.09 to 0.16 mm, and almost no corrosion occurs.

Comparative Example An aluminum alloy ingot having the composition shown in Table 3 was homogenized, hot-rolled, cold-rolled, intermediate annealed and finish cold-rolled under the same conditions as in Example 1 to obtain a thickness of 0.07 mm. I got the fin material. For the obtained fin material, tensile strength, electrical conductivity and natural electrode potential were measured in the same manner as in Example 1 to evaluate the high temperature buckling resistance and brazing property of the fin material, and for the joint portion between the fin and the plate. The maximum corrosion depth after the CASS test was measured. The results are shown in Table 4. In Table 3, the items that do not satisfy the conditions of the present invention are underlined.

[0023]

[Table 3]

[0024]

[Table 4] << Table Note >> High temperature buckling resistance of fin material: ◎ when the rate of change in fin height before and after brazing is 2.5% or less, ○, 2.5 to 5% is ○, and 5% or less is passed.

As shown in Table 4, none of the aluminum alloy fin materials satisfying the conditions of the present invention has sufficient performance as a heat exchanger fin material. Test material No.1
Has a high Mg content, which results in poor brazing properties and a low fin bonding rate, and when incorporated into a heat exchanger, deteriorates the thermal characteristics of the heat exchanger. In No. 2, since the Cu content is high and the natural electrode potential is noble, the sacrificial anode effect is poor and the maximum corrosion depth of the plate is large. No.3 and No.4 are Z
It was shown that the electrical conductivity was low and the thermal conductivity was poor because the content of r or Cr was large. No. 5 has a low Mn content, so the tensile strength is not sufficient. Since No. 6 had too much Mn content, hot rolling became difficult and hindered the production of fin material.

Since the test material No. 7 had a low Si content, the solid solution amount of Mn increased and the electrical conductivity was lowered, resulting in insufficient thermal conductivity. In No. 8, since the Si content was too high, the fin material locally melted during heating during brazing. Since No. 9 had a small Fe content, the solid solution amount of Mn increased and the electric conductivity decreased, resulting in insufficient thermal conductivity. Since No. 10 had a large Fe content, it was difficult to perform hot rolling, which hindered the production of the fin material. In No. 11, since the Zn content was small and the natural electrode potential was noble, the sacrificial anode effect was inferior and a through hole was formed in the plate in the CASS test. No.12 is Zn
Since the content is too large, the self-corrosion property becomes large and the corrosion consumption of the fin becomes remarkable, and the sacrificial anode effect of the fin material cannot be maintained for a long time. No. 13 corresponds to JIS 3004 alloy material, and its Mn and Si contents are low, so that its tensile strength is not sufficient, its electrical conductivity is low, and its thermal conductivity is insufficient. Further, since the Mg content was too large, the brazing property was poor, the fin bonding rate was low, and since Zn was not contained, the natural electrode potential became noble and a through hole was formed in the plate.

[0027]

As described above, according to the present invention, there is provided an aluminum alloy fin material which is excellent in brazing property, strength after brazing, thermal conductivity and sacrificial anode effect.
Therefore, the fin material can be made thinner, and the heat exchanger can be made lighter and have a longer life.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Kenji Kato 5-11-3 Shimbashi, Minato-ku, Tokyo Sumitomo Light Metal Industries, Ltd. (72) Inventor Yuji Suzuki 5-11-3 Shimbashi, Minato-ku, Tokyo No. Sumitomo Light Metal Industry Co., Ltd.

Claims (4)

[Claims] 1. Mn exceeds 1.5% (mass%, the same applies hereinafter)
2.2% or less, Si0.5-1.2%, Fe0.1-0.6%, Z
n 0.5-2.0%, 0.02% Mg as an impurity
A high-strength aluminum alloy fin material for a heat exchanger, which is limited to the following and consists of balance Al and inevitable impurities. 2. Mn more than 1.5% and 2.2% or less, Si0.5
.About.1.2%, Fe0.1.about.0.6%, Zn0.5.about.2.0%, Zr 0.25% or less, Cr 0.25% or less 1 type or 2 types, and Mg as impurities 0.02% or less. A high-strength aluminum alloy fin material for heat exchangers, characterized in that the balance is limited to Al and unavoidable impurities. 3. Mn more than 1.5% and 2.2% or less, Si0.5
~ 1.2%, Fe0.1-0.6%, Zn0.5-2.0%, Cu
A high-strength aluminum alloy fin material for a heat exchanger, which contains 0.3% or less, limits Mg as an impurity to 0.02% or less, and comprises the balance Al and unavoidable impurities. 4. Mn more than 1.5% and 2.2% or less, Si0.5
~ 1.2%, Fe0.1-0.6%, Zn0.5-2.0%, Cu
0.3% or less, Zr0.25% or less, Cr0.25
% Or less, and contains Mg as an impurity.
A high-strength aluminum alloy fin material for a heat exchanger, which is limited to 0.02% or less and is composed of balance Al and unavoidable impurities.