JP2846544B2 - Aluminum alloy high thermal conductive fin material - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high heat conductive aluminum fin material, and more particularly to a fin for a radiator, a heater, a condenser, etc. of a heat exchanger for an automobile manufactured by a brazing method. Is what is done.

[0002]

2. Description of the Related Art Most heat exchangers for automobiles use Al and Al alloys and are manufactured by a brazing method. Usually brazing is Al-S
An i-type brazing material is used, and brazing is performed at a high temperature of about 600 ° C.

In a heat exchanger such as a radiator, for example, as shown in FIG. 1, a thin fin (2) formed into a corrugated shape is integrally formed between a plurality of flat tubes (1), and the flat tubes (1) are formed. Are open in the space formed by the header (3) and the tank (4), respectively, and the high-temperature refrigerant passes through the flat tube (1) from the space on the one tank side to pass the high-temperature refrigerant on the other tank (4) side. The refrigerant is sent to the space, and the refrigerant, which has undergone heat exchange between the tube (1) and the fin (2), has been cooled, and is circulated again.

[0004] In recent years, heat exchangers have been reduced in weight and size in recent years. For that purpose, it is necessary to improve the heat efficiency of the heat exchanger, and it is desired to improve the thermal conductivity of the material. In particular, improvement in the thermal conductivity of the fin material has been studied, and a fin material of an alloy having an alloy component closer to pure aluminum has been proposed as a heat conductive fin. However, when the fins are thinned, if the fins are not strong enough, there is a problem that the fins are crushed when the heat exchanger is assembled, or broken when used as a heat exchanger. That is, a pure aluminum alloy fin has a disadvantage of insufficient strength, and a fin material having high strength and improved thermal conductivity has not yet been developed. This is because the addition of alloying elements such as Mn is effective for increasing the strength, but since there is brazing that is heated to around 600 ° C. in the process of manufacturing the heat exchanger, it is added to the alloy during brazing heating. This is because the element re-dissolves and hinders improvement in heat conduction.

[0005]

In view of the foregoing, the present invention has been made in view of the above, and in order to develop a fin material having high strength after brazing and high thermal conductivity, the amount of Si and Fe is optimized and the thermal conductivity is improved. The present invention was deemed to be able to solve the problem if an alloy element having a large effect of improving the strength could be found without lowering the thermal conductivity.

[0006]

[0007]

That is, the present invention provides a fin material having excellent heat conductivity and strength after brazing, and one of the fin materials is more than 0.3 wt% and 0.8 wt% or less of Si, 0.1 wt% or less. 5wt%
Over 1.5 wt% Fe, over 0.1 wt% 2.0
wt% or less Ni, and 2.0 wt% or less Z
n, at least 0.3 wt% of In, and at most 0.3 wt% of Sn, wherein at least one of them is contained, and the balance consists of aluminum and inevitable impurities.

Another fin material of the present invention is 0.3 wt%
More than 0.8 wt% of Si, more than 0.5 wt% and 1.5
wt% or less Fe, more than 0.1 wt% and 2.0 wt% or less N
i, containing not less than 0.01 wt% and not more than 0.2 wt% of Zr, and further not more than 2.0 wt% of Zn and not more than 0.3 wt% of I
n, containing one or more of Sn of 0.3 wt% or less, with the balance being aluminum and unavoidable impurities.

[0010]

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. Si improves the strength by its addition. In addition to improving the strength by solid solution hardening of Si itself, especially when coexisting with Fe or Ni,
Since it has the effect of promoting the precipitation of Fe and Ni, the amount of intermetallic compounds that contribute to dispersion strengthening is increased, and the strength is improved. Further, since the precipitation of Fe and Ni is promoted to reduce the amount of Fe and Ni dissolved in the fin material, the thermal conductivity is improved. If the Si content is less than 0.3 wt%, the effect of improving the strength is not sufficient. If the Si content is more than 0.8 wt%, the diffusion of the brazing during brazing heating increases, and the brazing property decreases. Therefore, Si exceeds 0.3 wt% and 0.8 wt%
Although it is as follows, it shows a stable characteristic especially at 0.4 to 0.6 wt%.

[0011] Fe is solid-solution hardened by a certain amount in the alloy, and the rest exists as an intermetallic compound. The former improves the strength, but greatly reduces the thermal conductivity. The latter slightly improves the strength by dispersion strengthening, but has the effect of forming an intermetallic compound with Si and conversely reducing the strength improving effect of the addition of Si. Here, if the amount of Fe added is 0.5 wt% or less, the effect of improving the strength is not sufficient, and if it exceeds 1.5 wt%, the formability is reduced and it becomes difficult to form corrugated fins.

Ni is an important additive element in the present invention, as a result of intensive studies by the present inventors, which has been found to have an effect of improving strength without lowering thermal conductivity. That is, Ni enhances the strength by solid solution hardening, but at the same time, has the effect of reducing the amount of Fe solid solution corresponding to the amount of Ni solid solution. When Fe and Ni form a solid solution, the effect of improving strength is almost the same,
The decrease in thermal conductivity is much smaller in Ni. Therefore, when Ni is added to the alloy containing the Fe amount, the strength is improved without lowering the thermal conductivity. If the amount of Ni is less than 0.1% by weight, the effect is not sufficient. If the amount exceeds 2.0% by weight, the formability is reduced and the fins cannot be corrugated.

Here, as an alloy for heat exchangers obtained by adding Ni to pure aluminum, there is an alloy disclosed in Japanese Patent Application Laid-Open No. 57-60046. However, although the invention of Japanese Patent Application Laid-Open No. 57-60046 is an alloy for a heat exchanger, it is not intended to use a fin as a refrigerant passage constituting member, because the invention has improved corrosion resistance and drooping property. It is obvious from the fact that there is no description about the sacrificial anode effect (deteriorating corrosion resistance) and thermal conductivity required for the fin material and that the plate thickness shown in the examples is much larger than that of the fin material. It is.

Further, in the invention of Japanese Patent Application Laid-Open No. 57-60046, there is no description on the concept of an alloy for a fin material having excellent thermal conductivity, and the amount of Fe and Ni, which are the basis of the present invention, are not described.
There is no description that captures the relationship with quantity. That is,
The invention of JP-A-57-60046 and the present invention are completely different in use and concept.

Further, regarding the alloy composition,
In the invention of Japanese Patent Publication No. 46, Si and Fe are considered as impurity elements, which is completely different from the present invention in which these are added as positively added elements.

[0016] In the present invention, the content further exceeds 0.01 wt% and 0.2 wt%.
% Or less of Zr may be added. Zr has a function of coarsening recrystallized grains generated at the time of brazing, preventing dripping of the fin and diffusion of the brazing into the fin. This alloy is F
Since e contains a relatively large amount, recrystallized grains may be fine. In such a case, Zr may be added. However, if Zr is added in an amount of 0.01 wt% or less, the function is not sufficient. However, the inventors have found that Zr
Is an element that has almost no function of improving the strength and lowers the thermal conductivity, so its upper limit is set to 0.2 wt%.

In the present alloy, Zn of 2.0 wt% or less is further added.
One or more of 0.3 wt% or less of In and 0.3 wt% or less of Sn may be added. These are added to impart a sacrificial anode effect to the fin material, and when added in amounts exceeding the above amounts, the thermal conductivity is reduced.

The inevitable impurities of the present alloy and elements added for reasons other than the above include Ti and B added for refining the ingot structure. If it is less than wt%, it may be added. Further, Cu, Mn, Mg, Na, Cd, Pb,
When elements such as Bi, Ca, Li, Cr, K, and V are added for reasons such as improvement in strength, prevention of ingot cracking, and improvement in formability, the essential condition is 0.03 wt% or less. All of these elements reduce the thermal conductivity when added in excess of 0.03 wt%.

Although the above is the alloy composition of the present invention, the fin material of the present invention can be used as a bare material, and can also be used as a core material of a brazing sheet fin. In the latter case, a conventionally used brazing alloy may be used as it is.

The heat exchanger using the fin material of the present invention includes, but is not limited to, a radiator, a condenser, an evaporator, and an oil cooler for an automobile.

The method of brazing the fins according to the present invention can be any of conventional non-corrosive flux brazing, flux brazing, vacuum brazing and the like.

The fins of the present invention can be manufactured by semi-continuous casting to produce an ingot, which can be produced in the steps of hot rolling, cold rolling and annealing, and in continuous casting rolling, cold rolling and annealing. It can also be manufactured by a process.

[0023]

The present invention will be specifically described below with reference to examples. Aluminum alloy fin material (thickness) shown in Table 1
60 μm, H14 temper) was produced by a conventional method. And the strength and electrical conductivity of these fin materials after the heat of brazing were measured,
Table 2 shows the results. Note that the condition of the soldering heat was 600 ° C. × 5 minutes in nitrogen gas. Here, the electrical conductivity is an index of 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%.

[0024]

[Table 1]

[0025]

[Table 2]

As is clear from Table 2, the fin materials of the conventional example and the comparative example have no excellent tensile strength and electrical conductivity, whereas the fin material of the present invention has both tensile strength and electrical conductivity. It shows excellent values.

[0027]

As described above, the fin material of the present invention has high strength and excellent heat conductivity, and has remarkable industrial effects such as greatly improving the quality of heat exchangers for automobiles.

[Brief description of the drawings]

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

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Flat tube 2 Fin 3 Header 4 Tank

Continuation of the front page (56) References JP-A-58-6956 (JP, A) JP-A-2-133540 (JP, A) JP-B-55-27613 (JP, B2) (58) Fields investigated (Int) .Cl. ⁶ , DB name) C22C 21/00-21/18 F28F 1/32 F28F 21/08

Claims (2)

(57) [Claims] 1. S content exceeding 0.3 wt% and not more than 0.8 wt%.
i, more than 0.5 wt% and less than 1.5 wt% Fe, 0.1 wt%
% And not more than 2.0 wt% of Ni.
An aluminum alloy fin material containing one or more of Zn by wt% or less, In by 0.3 wt% or less, and Sn by 0.3 wt% or less, with the balance being aluminum and unavoidable impurities. . 2. The amount of S exceeding 0.3% by weight and 0.8% by weight or less.
i, more than 0.5 wt% and less than 1.5 wt% Fe, 0.1 wt%
%, More than 2.0 wt% Ni, more than 0.01 wt% and less than 0.2 wt% Zr, furthermore, less than 2.0 wt% Zn, less than 0.3 wt% In, less than 0.3 wt% Sn
An aluminum alloy fin material comprising at least one of the foregoing, and the balance consisting of aluminum and unavoidable impurities.