JPH03104836A - Aluminum alloy fin material for vapor phase brazing - Google Patents

Abstract

PURPOSE:To obtain the Al alloy material for a fin having excellent vapor phase brazability by adding specified amounts of Mg, Si, Fe and other specified metallic elements to Al. CONSTITUTION:As a fin material for a heat exchanger, an Al alloy having a compsn. contg., by weight, >0.6 to 2.5% Mg, <1.0% Si, <1.2% Fe and <0.6% Mn, furthermore contg. one or more kinds among <0.3% Zr, <0.3% Cr and <1.0% Ni and the balance Al is used. The Al alloy material for a heat exchanger fin suitable for vapor phase brazing in a nonoxidizing atmosphere of N2, Ar, CO, etc., in which the flux vapors of a potassium fluoroaluminate complex or the like are present and having excellent strength after brazing can be manufactured.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an aluminum alloy fin material for vapor phase brazing, which is brazed in a non-oxidizing atmosphere in the presence of flux vapor such as potassium fluoroaluminate complex. It is something.

[Prior art and problems to be solved by the invention] Normally, aluminum or aluminum alloy is brazed by fixing it to the aluminum or aluminum alloy member to be joined via a brazing material whose melting point is lower than that of aluminum, etc. This is done by heating the assembled product to a temperature higher than the melting point of the brazing filler metal and lower than the melting point of the aluminum or aluminum alloy members to be joined. The brazing material is generally Al-Si.
Brazing sheet is a plate-shaped, wire-shaped, or powdered brazing material, or a laminated material in which a core material made of aluminum or an aluminum alloy is coated with the brazing material (hereinafter referred to as "plating sheet"). It is used as.

Conventional brazing methods include a flux brazing method that uses flux to remove an oxide film on the surface of the members to be brazed, and a vacuum brazing method that does not use flux.

The above flux brazing methods include immersion brazing, in which the assemblies to be joined are immersed in molten chloride-based flux and heated for brazing, and immersion brazing, in which the assemblies to be joined are coated with chloride-based flux. There are also furnace brazing methods, in which the brazing is heated in a furnace. However, since this chloride-based flag is corrosive to aluminum, it must be completely removed by cleaning after brazing, making the manufacturing process very complicated.

On the other hand, according to the vacuum brazing method, in which the assembly to be joined is placed in a vacuum and subjected to brazing heat, there is no need for cleaning as a post-process, and the surface of the parts after brazing is also good. There are problems such as equipment limitations such as the need for high vacuum and material limitations.

As a brazing method to solve these problems, a method of brazing in a furnace using fluoride flux has come to be widely used. This method is used as flags for non-hygroscopic and non-corrosive aluminum.
A mixture of F a and K3 AIF6 is used, suspended in water, and applied to the surfaces of the assemblies to be joined for brazing.The characteristic of this method is that the flux must be removed in order to use a non-corrosive flux. One of the advantages is that there is no need for post-processing steps. However, this brazing method requires a coating and drying process to adhere the flux to the surface of the assembly, and the applied flux falls off from the assembly while it is being transported to the next process. Therefore, the yield of effectively used flux decreases. In addition, since flux residue remains unevenly on the surface of the bonded member after soldering F4, the surface becomes dirty and the commercial value is inferior compared to the conventional vacuum brazing method. When chromate treatment or black paint treatment is performed on the product, the results are uneven and the effect is not fully demonstrated. In addition, in this brazing method, in order to prevent a reaction between the flux and the aluminum alloy during the brazing heat, an alloy is used in which the amount of Mg added is regulated.

By the way, recently, as a new brazing method to solve the problems of these brazing methods, a non-oxidizing brazing method in which flux vapor such as potassium fluoroaluminate complex is present, without applying flux to the entire surface of the parts to be joined, has been proposed. A vapor phase brazing method has been developed in which brazing is performed in a neutral atmosphere. Although this brazing method solves the conventional problems, when brazing using the same composition alloy used for conventional brazing with non-corrosive flux such as potassium fluoroaluminate complex, This is a problem as it may not be possible to braze properly.

[Means to solve the problem]

In view of this, as a result of various studies, the present invention has developed an aluminum alloy fin material for vapor phase brazing suitable for the above-mentioned vapor phase brazing. Exceeding 6wt% 2.51
Vl% or less (hereinafter W1% is abbreviated as %), Sil. 0% or less, Fe I. 296 or less, and further contains M
n16% or less, ZrL3% or less. CrQ. j% or less, N
il. It is characterized by containing one or more of these within a range of Q% or less, with the remainder consisting of aluminum and unavoidable impurities.

[For production]

First, the alloy phase formation of the present invention will be explained in detail. Mg
As mentioned above, because it reacts with flux, it was thought that it should not be added to alloys used for non-corrosive flag brazing, such as potassium fluoroaluminate complex. However, as a result of various studies conducted by the present inventors, it was discovered that vapor phase brazing, in which brazing is performed in flux vapor, has the effect of improving brazability, which led to the present invention. be. In other words, in vapor phase brazing, brazing is performed by destroying the oxide film on the alloy surface with flags vapor in a non-oxidizing atmosphere, but since Mg easily reacts with flux vapor, the flux vapor may damage the material. It becomes easy to adhere to the surface of. This is because the flux vapor uses this as a core to destroy the oxide film on the alloy surface. For alloys that do not contain Mg, if the amount of flux vapor is unstable, the above-mentioned flux cores will be difficult to adhere to the material surface, and the reaction between the black vapor and the oxide film will be insufficient, resulting in poor brazing. It causes The reason why the addition of Mg improves brazing properties is that the amount of flux used in vapor phase brazing is extremely small compared to conventional brazing in which 7 lux is applied.

Further, the addition of Mg has the function of improving the room temperature strength of the alloy, and this makes it possible to make the fins thinner. Here, the reason why the amount of Mg added is more than 0.6% and less than 2.5% is because if it is less than 0.6%, the strength improvement effect is insufficient, and if it exceeds 2.5%, the alloy will deteriorate due to brazing heating. This is because it will melt.

Si has the function of improving the strength of the alloy.

In particular, in the alloy of the present invention, Mg2Si is finely precipitated together with Mg to improve the strength. However, if the amount exceeds 1.0%, the melting point of the alloy will decrease and it will melt during brazing heating, so the upper limit is set at 1.0%.

Fe has the effect of increasing the high temperature strength of the alloy and preventing deformation during brazing heating. However, if the amount added exceeds 1.2%, the crystal grain size becomes fine due to the effect of increasing the amount of the AI-Fe-based intermetallic compound, causing high-temperature creep, and conversely, the high-temperature strength decreases. Therefore, the amount of Fe added is 1.2% or less.

Mn, Zr, Cr, and Ni all form intermetallic compounds in the fin material that are stable up to high temperatures, and have the function of increasing the high-temperature strength of the fin. Therefore, Mn of 0.6% or less,
0.3% or less Zr, 0.3% or less Cr. 1
．． One or more types of Ni are added in an amount of 0% or less. However, the addition of Mn exceeding 0.6% reduces the thermal conductivity of the fins, and the addition of Zr exceeding 0.3%, Cr exceeding 0.3%, and Ni exceeding 1.0% will eventually reduce the thermal conductivity of the fin. This not only causes cracks in the ingot during casting, but also reduces the rolling workability of the alloy. Therefore, the upper limit of each addition is determined as above.

The above is the composition of the alloy of the present invention, but the alloy of the present invention contains unavoidable impurities such as Ti and B, which are added as grain refiners during casting, and which are added for the purpose of strength, formability, castability, etc. , Cu, Ca, V, Bi, Pb, Ag. Be
There is no problem in containing less than 0.05% of each of the following elements.

Next, vapor phase brazing in which such an alloy of the present invention is used will be briefly explained. The vapor phase brazing method is a method in which the oxide film on the surface of the material is destroyed using a non-corrosive flux vaporized in a non-oxidizing atmosphere, and then the material is brazed. By using such vaporized flux, the amount of flux used can be reduced and a structure with a clean surface can be obtained. The flux used here includes potassium fluoroaluminate complex, and the non-oxidizing atmosphere is nitrogen, argon, etc. Carbon monoxide etc. are used.

Examples of heat exchangers using this fin material include radiators, evaporators, and condensers.

〔Example〕

The present invention will be explained in detail below based on Examples.

After facing the composition alloy ingot (400mm) shown in Table 1,
Perform homogenization treatment at 520°C for 2 hours, and continue as is in 3.
Hot rolling was performed up to Offin. This hot rolled plate is 0
．． After cold rolling to IOnn and annealing at 360°C for 2 hours, 0. Cold rolled to 07mIm,
Obtained fin material.

This fin material and plate thickness 0. 4mm tube material (core material 3
003, outer skin material 4343: 10%, inner skin material 70
72:10%) and plate thickness 1. 6mm header material (core material 3003, inner skin material 4343: 8%, outer skin material 707
2: 1G%) and the tube shown in Figure 1 (2: 1G%).
), a header plate (3) is attached to both ends of the tube (2) to form a core (4), and a resin tank ( 6) was manufactured under the brazing conditions shown in Table 2. Table 3 shows the brazing conditions used for each fin material.

Table 4 shows the brazing conditions of the radiator after the above brazing.

Furthermore, this fin material was heated at 610° C. for 5 minutes and subjected to a tensile test. The results are shown in Table 4.

Table 1 Unit W1% Table 2 As is clear from Tables 1 to 4, the radiator using vapor phase brazing using the alloy fins of the present invention exhibits excellent properties, and the fin material itself The strength after heating is also excellent.

〔Effect of the invention〕

As described above, the alloy fin material of the present invention has excellent brazing properties in vapor phase brazing and a clean surface quality after brazing, and also has superior strength after brazing compared to conventional fins, making it possible to make thin fins. It has remarkable industrial effects, such as the ability to

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram showing an example of a radiator with a portion cut away. 1...Fin 2...Tube 3...
Header plate 4...Core 5...Packing
6...Resin tank Figure 1

Claims (1)

[Claims] (1) Mg exceeding 0.6 wt% and 2.5 wt% or less, Si
Contains 1.0 wt% or less, Fe 1.2 wt% or less, and further contains Mn 0.6 wt% or less, Zr 0.3 wt% or less,
An aluminum alloy fin material for vapor phase brazing, containing one or more of 0.3 wt% or less of Cr and 1.0 wt% or less of Ni, with the balance being aluminum and inevitable impurities.