JP2000160271A - Aluminum alloy fin material for brazing and heat exchanger using the fin material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a high strength and high thermal conductivity aluminum alloy fin material suitably used for a heat exchanger using a thin tube and to provide a heat exchanger using the fin material. SOLUTION: An aluminum alloy fin material for brazing and a heat exchanger using the fin material has a compsn. contg., by weight, >0.03 to 1.2% Si, >0.1 to 2.5% Fe, >2 to 6% Zn, one or two kinds of >0.1 to 3.0% Ni and >0.1 to 3.0% Co, and the balance Al with inevitable impurities. Since this fin material has high strength and high thermal conductivity and furthermore contains a suitable amt. of Zn, the heat exchanger produced by combining the fin material with a thin tube and executing brazing is excellent in external corrosion resistance.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a high-strength, high-thermal-conductivity aluminum alloy fin material suitably used for a heat exchanger using a thin-walled tube, and a radiator, heater, condenser, evaporator and the like using the fin material. Heat exchanger.

[0002]

2. Description of the Related Art Most heat exchangers for automobiles use Al and A.
1 alloy is used and is manufactured by a brazing method. Normally, brazing is performed at a high temperature of about 600 ° C. using an Al—Si alloy as a brazing material. A heat exchanger such as a radiator is, for example, integrally formed with corrugated fins (2) between a plurality of flat tubes (1) as shown in FIG. Open in the space formed by the header (3) and the tank (4), respectively, and allow the high-temperature refrigerant to pass through the flat tube (1) from the space on the one tank side to the other tank (4).
The refrigerant is sent to the space on the side, and the refrigerant which has been cooled by the heat exchange between the flat tube (1) and the fin (2) is circulated again. For the flat tube, a brazing sheet having a three-layer structure in which a brazing material of an Al-Si alloy is clad on one surface of a core material of an Al-Mn alloy and a sacrificial material of an Al-Zn alloy is clad on the other surface. Those subjected to electric resistance welding with the side outside are often used.

[0003]

In recent years, the thickness of the tube material has been reduced to reduce the weight of the heat exchanger, and the thickness of the core material of the brazing sheet has been reduced. When the core material becomes thinner, the sacrificial material (Al
-Zn alloy) has a problem that the external corrosion resistance of the heat exchanger is significantly reduced due to the diffusion of Zn to the outer surface of the tube by heating during brazing. In order to improve the thermal conductivity, the fin material is a high-strength, high-thermal-conductivity fin material in which the alloy component is close to that of pure aluminum, for example, an alloy obtained by adding Ni or Co to an Al—Si—Fe alloy (see Kaihei 8-10934)
Although fin materials have been proposed, they have not been adequately adapted to thin-walled tubes. An object of the present invention is to provide a high-strength, high-thermal-conductivity aluminum alloy fin material capable of improving the external corrosion resistance of a heat exchanger using a thin-walled tube, and a heat exchanger using the fin material.

[0004]

According to the first aspect of the present invention,
Si more than 0.03 wt% and less than 1.2 wt%, Fe0.1 wt%
More than 2.5 wt%, more than 2 wt% Zn, less than 6 wt%, more than 0.1 wt% Ni, less than 3.0 wt%, 0.1 wt% Co
% Or more and 3.0 wt% or less, and is a brazing aluminum alloy fin material comprising the balance of Al and inevitable impurities.

According to a second aspect of the present invention, there is provided a semiconductor device comprising:
Exceeding 1.2% by weight, Fe exceeding 0.1% by weight and 2.5% by weight, Zn exceeding 2% by weight and 6% by weight, Zr 0.3% by weight or less, Ni exceeding 0.1% by weight and 3.0% by weight, Co0.
An aluminum alloy fin material for brazing containing one or two of more than 1% by weight and 3.0% by weight or less, with the balance being Al and unavoidable impurities.

According to a third aspect of the present invention, there is provided:
Exceeding 1.2 wt%, Fe over 0.1 wt%, up to 2.5 wt%, Zn over 2 wt%, up to 6 wt%, Ni over 0.1 wt%
% Over 3.0% by weight, Co over 0.1% by weight and 3.0% by weight
It contains one or two of the following, and further contains In0.
One or more of 3 wt% or less and Sn 0.3 wt% or less
It is an aluminum alloy fin material for brazing containing a seed and the balance of Al and unavoidable impurities.

According to a fourth aspect of the present invention, there is provided a semiconductor device comprising:
Exceeding 1.2% by weight, Fe exceeding 0.1% by weight and 2.5% by weight, Zn exceeding 2% by weight and 6% by weight, Zr 0.3% by weight or less, Ni exceeding 0.1% by weight and 3.0% by weight, Co0.
Contains one or more of more than 1 wt% and less than or equal to 3.0 wt%, contains one or more of less than 0.3 wt% of In and less than or equal to 0.3 wt% of Sn, with the balance being Al and unavoidable impurities Aluminum alloy fin material for brazing.

According to a fifth aspect of the invention, there is provided a tube containing not less than 1.5 wt% of Zn and having a lining material having a thickness of not less than 30 μm and a thickness of not more than 0.2 mm. A heat exchanger characterized by being manufactured by brazing by combining any of the fin materials described above.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The role of the additional elements in the fin material of the present invention and the reasons for limiting the alloy composition will be described below.
Si contributes to strength improvement by solid solution hardening,
When Fe, Ni, Co and the like coexist, the above-mentioned Fe, N
It promotes precipitation of i, Co, etc., and also improves strength by dispersion strengthening. If the Si content is less than 0.03% by weight, the effect cannot be sufficiently obtained, and if it exceeds 1.2% by weight, the fins are melted when the soldering heat is applied. Therefore, Si is 0.03wt
% And not more than 1.2 wt%. In particular, 0.3 wt% or more is desirable from the viewpoint of solid solution hardening, and 0.8 wt% or less is desirable from the viewpoint of electrical conductivity.

[0010] A certain amount of Fe forms a solid solution in the alloy, and the rest is distributed as an intermetallic compound. Solid solution Fe improves strength by solid solution hardening, but greatly reduces thermal conductivity. The intermetallic compound improves the strength by dispersion hardening. Solid solution Fe
Although the improvement in strength can be seen even in a place where the Fe content is small, a sufficient strength improvement cannot be obtained with 0.1 wt% or less.
If it exceeds 2.5% by weight, the corrugated formability of the fins is reduced. Therefore, Fe is defined to be more than 0.1 wt% and 2.5 wt% or less.

[0011] Zn is a particularly important alloying element when a fin is combined with a thin tube. Zn in the fin is
During brazing, it diffuses into the molten brazing material and becomes Zn vapor and is directly absorbed by the brazing material. Z absorbed by brazing material
n diffuses into the tube core, creating a gradient in which the amount of Zn decreases from the tube outer to the interior. This gradient counteracts the gradient in which the amount of Zn decreases from the lining side of the tube toward the outside, and as a result, rapid progress of corrosion from the outer surface to the inside of the tube is suppressed. If the Zn content is less than 2 wt%, the above effect cannot be sufficiently obtained, and if it exceeds 6 wt%, the melting point of the fin is lowered and the fin is melted during brazing. In particular, a desirable Zn content is 3 to 5 wt%.

Ni contributes to an increase in strength without lowering the thermal conductivity. Ni improves the strength by solid solution hardening,
At the same time, it has the effect of reducing the amount of Fe solid solution corresponding to the amount of Ni solid solution. The effect of improving the strength in the solid solution state of Fe and Ni is almost the same, but the decrease in thermal conductivity is much smaller in Ni. For this reason, alloys containing Fe
When added, the strength can be improved without significantly lowering the thermal conductivity. Further, Ni has the effect of finely distributing the Al-Fe intermetallic compound. Usually, the Al-Fe intermetallic compound is crystallized during casting and is divided during rolling to be finely distributed, but the Al-Ni intermetallic compound is crystallized while dividing the Al-Fe intermetallic compound during casting. Therefore, the Al-Fe-based intermetallic compound is likely to be finely divided during rolling. As described above, when the Al-Fe-based intermetallic compound is finely divided, the strength is improved, and the number of nucleation sites for recrystallization during brazing is reduced, so that the recrystallized grains are coarse and diffusion of the brazing hardly occurs. Become. When the content of Ni is 0.1 wt%, the effect cannot be sufficiently obtained. When the content exceeds 3.0 wt%, the corrugating formability of the fin material is reduced.

Co works similarly to Ni, but N
In addition to slightly lowering the thermal conductivity compared to i,
The breaking effect of the l-Fe intermetallic compound is small. In the present invention, it is possible to use Co instead of Ni, or to add Ni and Co in combination, but the effect of adding only Ni is greater. The lower limit of the amount of Co added is 0.1 wt%,
In the case of adding Ni in combination, it is effective even at 0.1 wt% or less.

Zr coarsens the recrystallized grains generated during brazing to improve the droop resistance of the fin and also prevents the diffusion of the braze into the fin. If Zr is contained in excess of 0.3 wt%, a coarse Zr-based compound is formed and the moldability is reduced.

In and Sn enhance the sacrificial anode effect of the fin material. If the content of these elements exceeds 0.3% by weight, the thermal conductivity is greatly reduced.

Next, unavoidable impurities and elements added for reasons other than the above will be described. Ti, B, etc. added for refining the ingot structure may be added as long as each is 0.03 wt% or less. Mn added for the purpose of improving strength, preventing ingot cracking, improving formability,
Mg, Na, Cd, Pb, Bi, Ca, Li, Cr,
Elements such as K and V are required to be 0.03 wt% or less in order to reduce thermal conductivity. Cu is 0.2
It can be added up to wt%. Cu has a small effect on the decrease in thermal conductivity as compared with Mn or the like, but when it exceeds 0.2 wt%, the sacrificial effect of the fins decreases.

The fin material of the present invention is preferably used as a bare material. The reason for this is that when used as the core material of the brazing sheet, the fins are crushed more greatly because the Zn content is large. Heat exchangers to which the fin material of the present invention can be applied include, but are not limited to, radiators, condensers, evaporators, and oil coolers for automobiles.

The fin material of the present invention has a Z content of 1.5 wt% or more.
When used in a heat exchanger manufactured by brazing in combination with a thin tube having a thickness of not more than 0.2 mm and containing a lining material having a thickness of not less than 30 μm, the effect of improving the external corrosion resistance of the tube. Having. 0.2 m thick containing 1.5 wt% or more of Zn and having a lining material of 30 μm or more in thickness
m or less is a tube whose internal corrosion resistance has been ensured and a thinner wall has been achieved. Such a tube has a very thin core material as compared with a conventional tube, and has a lining material (sacrificial material) at the time of brazing. This is a tube having poor external corrosion resistance, because Zn in) diffuses to the brazing material side. However, even in a heat exchanger using such a tube, the external corrosion resistance of the heat exchanger can be improved by combining the fin material of the present invention.

The fin material of the present invention can be satisfactorily brazed by conventional brazing methods such as non-corrosive flux brazing, flux brazing and vacuum brazing. The fin material of the present invention can be manufactured in the steps of hot rolling, cold rolling and annealing by manufacturing an ingot by a semi-continuous casting method, and can also be manufactured in the steps of continuous casting and rolling and cold rolling and annealing. It is possible.

[0020]

The present invention will be specifically described below with reference to examples. (Example 1) An aluminum alloy having the composition of the present invention shown in Table 1 was processed into a sheet having a thickness of 4 mm by a continuous casting and rolling method, wound around a coil, and the sheet was supplied from the coil to perform cold rolling, annealing, and the like. Cold rolling was performed in order to produce a fin material having a thickness of 0.06 mm. Here, the cold rolling reduction after the final annealing was 25%.

Comparative Example 1 A fin material was manufactured in the same manner as in Example 1 except that the composition of the comparative example shown in Table 1 and a conventional alloy were used.

Each of the fin materials manufactured in Example 1 and Comparative Example 1 was slittered to a width of 16 mm, corrugated, and combined with a thin-walled tube and a header plate, and brazed, and the heat was applied as shown in FIG. The exchanger was manufactured. In the brazing, a fluoride-based flux is applied,
The heating was performed at 600 ° C. for 5 minutes in a nitrogen gas atmosphere.

The thin tube is made of Al-0.5% Cu-
4045 alloy (brazing material) on one side of 1% Mn alloy core material,
A 0.2 mm-thick brazing sheet strip was formed by cladding an Al-4% Zn alloy (sacrificial material) on the other side, and the brazing sheet was subjected to ERW with the brazing material on the outside and a width of 16 m.
m into a flat tube. A 1.2 mm thick brazing sheet having the same configuration as above was formed into a header plate. The thickness ratio of the brazing material / core material / sacrifice material of each of the brazing sheets is 12:63:25.

The obtained heat exchanger was subjected to a CASS test (JISH8681) for 1,000 hours, and the tube after the test was evaluated for external corrosion resistance by examining the tube for liquid leakage and the size of pitting corrosion of the tube. Further, the conductivity of the fin material after the heat of brazing was measured. Here, the electrical conductivity is an index of the thermal conductivity. When the electrical conductivity of the fin is improved by 5% IACS, the thermal efficiency of the heat exchanger is improved by about 1%. Table 2 shows the results.

[0025]

[Table 1]

[0026]

[Table 2]

As is clear from Table 2, No. 1 of the present invention example
Nos. 8 to 8 were excellent in external corrosion resistance, had shallow pitting and did not cause liquid leakage. This is because Zn is contained in an appropriate amount. The conductivity of the fin material of the present invention is the same as that of the comparative example.
Similar to Fe-Ni (Co) alloy fins, conventional materials (N
o.15, an Al-Mn alloy), which contributes to improving the thermal efficiency of the heat exchanger. On the other hand, the comparative example No. 9
No. 14 and No. 15 of the conventional product all had a through-hole in the tube, causing liquid leakage and inferior external corrosion resistance.

The heat exchange was performed by brazing the conventional flat tube made of a brazing sheet strip having a thickness of 0.35 mm with the fin material of Example 1 (Example of the present invention) and Comparative Example 1 (including the conventional material). The same is true for vessels
The S test was performed, but no liquid leakage occurred and the pitting corrosion was shallow.

[0029]

As described above, the fin material of the present invention has high strength and high thermal conductivity and contains an appropriate amount of Zn. Therefore, the fin material is combined with a thin tube and brazed. The manufactured heat exchanger has excellent external corrosion resistance. Therefore, an industrially remarkable effect is achieved.

[Brief description of the drawings]

FIG. 1 is a partially sectional perspective view showing a radiator.

[Explanation of symbols]

 1 flat tube 2 fins 3 header 4 tank

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) F28F 21/08 F28F 21/08 B (72) Inventor Jun Fukuda 1-1-1 Showa-cho, Kariya-shi, Aichi Stock Inside Company Denso (72) Inventor Taketoshi Toyama 1-1-1, Showa-cho, Kariya-shi, Aichi Prefecture Inside Denso Corporation (72) Inventor Yoshihiko 1-1-1, Showa-cho, Kariya-shi, Aichi Prefecture Inside Denso Corporation

Claims (5)

[Claims] (1) more than 0.03 wt% of Si and not more than 1.2 wt%;
Fe over 0.1 wt%, up to 2.5 wt%, Zn over 2 wt% 6
wt% or less, contains one or two of Ni more than 0.1 wt% and less than 3.0 wt%, Co more than 0.1 wt% and less than 3.0 wt%, and the balance consists of Al and inevitable impurities. Aluminum alloy fin material. 2. Si is more than 0.03 wt% and 1.2 wt% or less;
Fe over 0.1 wt%, up to 2.5 wt%, Zn over 2 wt% 6
wt% or less, Zr 0.3 wt% or less, Ni 0.1 wt%
% Over 3.0% by weight, Co over 0.1% by weight and 3.0% by weight
An aluminum alloy fin material for brazing containing one or two of the following, the balance being Al and unavoidable impurities. 3. Si is more than 0.03 wt% and 1.2 wt% or less;
Fe over 0.1 wt%, up to 2.5 wt%, Zn over 2 wt% 6
wt% or less, one or two of Ni more than 0.1 wt% and less than 3.0 wt%, Co more than 0.1 wt% and less than 3.0 wt%, and further In0.3 wt% or less, Sn
An aluminum alloy fin material for brazing containing one or two of 0.3 wt% or less, the balance being Al and unavoidable impurities. 4. An amount of Si exceeding 0.03% by weight and 1.2% by weight or less,
Fe over 0.1 wt%, up to 2.5 wt%, Zn over 2 wt% 6
wt% or less, Zr 0.3 wt% or less, Ni 0.1 wt%
% Over 3.0% by weight, Co over 0.1% by weight and 3.0% by weight
Contains one or two of the following, In0.3 wt%
Hereinafter, an aluminum alloy fin material for brazing containing one or two of Sn of 0.3 wt% or less, the balance being Al and unavoidable impurities. 5. A composition containing not less than 1.5 wt% Zn and a thickness of 30 wt.
A tube having a thickness of 0.2 mm or less having a lining material of at least μm and a fin material according to any one of claims 1, 2, 3, and 4, and being manufactured by brazing. Heat exchanger.