JPH03230890A - Aluminum alloy brazing material - Google Patents

Abstract

PURPOSE:To allow the brazing of members which are difficult to be brazed and to securely join the joining members by specifying the compsn. of the aluminum alloy brazing material. CONSTITUTION:The aluminum alloy brazing material contains 4 to 12wt.% Si, 15 to 55wt.% Zn and 0.2 to 2.0wt.% Cu and consists of the balance aluminum and unavoidable impurities. This brazing material flows adequately and forms a sufficient fillet in the joint part even in the case of brazing of particularly casting materials, and above all, casting materials and die castings having a low solidus line temp., such as AC4C, and high tensile alloy, such as 2219 alloy of an Al-Cu system not to mention the case of mutual brazing of a malleable aluminum. These joining members which are heretofore difficult to be brazed are, therefore, surely and securely joined.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application This invention relates to aluminum alloy brazing filler metals, particularly aluminum alloy castings, die castings, Aρ-Cu series, AM-Cu-M
The present invention relates to an aluminum alloy brazing material suitably used for brazing joining members including g-based, AΩ-Zn-Mg-based high-strength alloys, and the like.

2. Description of the Related Art When joining members made of aluminum or its alloy are brazed to each other, an AΩ-8i type brazing material has conventionally been used. By the way, for example, aluminum intake manifolds for automobiles, which are formed by brazing wrought materials and cast materials, and various parts used in moving vehicles, industrial machinery, home appliances, office equipment, etc. When casting materials, die casting, high-strength alloys, etc. are included, it is necessary to use a material with a low melting point as a brazing material since the melting point of the casting materials is generally low. Therefore, in such brazing, a brazing material made by adding zinc and copper to an Afl-8i alloy to lower the melting point has been used.
A typical example is 4245, which is the lowest melting point brazing material in existence.
Alloy (representative composition A [-10wt%SL-10wt%Zn
-3wt%Cu).

Problems to be Solved by the Invention However, even when such a brazing material is used, depending on the type of casting material, the melting point is still too high, making it difficult to perform good brazing.

In other words, when brazing a casting material such as AC4C, for example, the solidus temperature of AC4C is 577°C, so the liquidus temperature of the brazing material should be about 547°C, which is about 30°C lower. is desirable, but even the representative composition of the 4245 alloy mentioned above has a liquidus temperature of 560°C (solidus temperature of 510°C).
Therefore, it was not possible to fully demonstrate its function as a brazing filler metal.

This invention was made in view of the above circumstances, and aims to reduce the melting point of materials that are conventionally difficult to braze, such as cast materials such as AC4C, die cast materials such as ADC12, and high-strength alloys. The purpose of the present invention is to provide an aluminum alloy brazing filler metal that can be bonded.

Means for Solving the Problems For the above purpose, the present invention basically provides an AΩ-8i-Zn alloy containing a high concentration of 2n.
In addition to lowering the melting point of the brazing filler metal, since Zn can make the brazed joint electrically less noble, depending on the usage environment, the brazed joint may selectively corrode and reduce its strength. The idea is to add Cu to shift the natural electrode potential to the noble side.

So, this invention, Si: 4-12wt%, 2n
: 15 to 55 wt%, Cu: 0. 2-2. 0
wt%, and the remainder consists of aluminum and unavoidable impurities.

To explain the significance of adding each element in the brazing material of the present invention and the reason for its limitation, Si is necessary for lowering the melting point of the brazing material and increasing fluidity. However, if the content is less than 4 wt%, these effects will be poor, and if the content exceeds 12 wt%, the melting point will rise sharply, making it impossible to use it as a brazing filler metal. A particularly preferable content of Si is 5 to 8 wt%.

Zn is an extremely effective element for lowering the melting point of brazing filler metal. However, if the content is less than 15 wt%, the effect will be poor, and if it exceeds 55 wt%, processability will deteriorate. A particularly preferable Zn content is 20 to 50 νt%.

Cu can be added to Z without interfering with the low melting point effect of Si or Zn.
By containing a high concentration of n, the brazed joint (
It plays the role of preventing the corrosion of the joint by preventing the natural electrode position of the fillet (fillet) from becoming base and shifting the potential towards the base. However, the content is 0. 2wt%
If it is less than that, the above effects will be poor. On the other hand, if it exceeds 2 wt%, workability deteriorates. A particularly preferable content of Cu is
It is 0.5 to 1.5 wt%.

In addition to the above-mentioned essential elements, Be may be contained within a range of about 1 wt % or less in order to improve mechanical properties and the like.

The method for producing the aluminum alloy brazing material according to the present invention is not particularly limited, and for example, it may be extruded into a wire rod by an extrusion method according to a conventional method, or it may be drawn into a wire rod, or hot rolling according to a conventional method. It may be manufactured into a plate material or the like by cold rolling, or any other manufacturing method may be applied. Although it is of course possible to use this brazing filler metal alone, it can also be used in the form of a plating sheet made of pure Aρ such as A11oO11050 or A30033003 alloy and clad with this brazing filler metal on one or both sides as a skin material. May be used in When this brazing filler metal is used in the form of a plating sheet, it has the advantage of being easier to process than when it is used alone.

Effects of the Invention The aluminum alloy brazing material according to the present invention has a melting point much lower than that of conventionally known brazing materials by combining each element within a predetermined range. Therefore, it is useful not only for brazing aluminum wrought materials, but also for casting materials, especially casting materials with a low solidus temperature such as AC4C, die casting, and high strength alloys such as Aρ-Cu-based 2219 alloy. Even when brazing, it can flow appropriately and form a sufficient fillet at the joint, making it possible to achieve reliable and strong joining of these joining members, which has been difficult in the past.

Therefore, by applying it to split casting and joining of cast materials,
It becomes possible to provide a variety of complex and thin-walled components that are not available in the past.

In addition, according to the brazing material of the present invention, it is possible to braze AΩ and SUS, etc. at a relatively low temperature, thereby suppressing the growth of a brittle alloy layer, and making it possible to braze dissimilar metals, which was not possible before. .

Furthermore, according to the alloy brazing material of the present invention, the natural electrode potential can be shifted in a negative manner despite containing a high concentration of Zn, so that corrosion of the brazed joint can be prevented and a brazed product with excellent corrosion resistance can be provided. It becomes possible.

Example Next, examples of this invention will be shown.

Aluminum alloy billets having various compositions shown in Table 1 were cast by a conventional method, and then hot extruded into wire rods to obtain various brazing filler metals.

Next, for each brazing filler metal obtained above, its solidus temperature and liquidus temperature were examined, and the natural electrode potential was measured. Note that the natural electrode potential was measured using a 2.67% AΩCρ3 aqueous solution (liquid temperature: 40°C). The results are also shown in Table 1.

Next, brazing was performed using the above brazing filler metal, and its brazing properties were examined. Brazing involves assembling an aluminum cast pipe made of AC4C to a pure aluminum plate so that the end of the pipe is in contact with the plate surface, placing each brazing filler metal near the inside of the contact area between the aluminum plate and the cast pipe, and applying chlorine. Brazing was carried out in a furnace using system flux at an ambient temperature of 560°C. Then, the condition of the joints of the wax parts was visually observed. The results are also shown in Table 1.

[Left below] As is clear from the results in Table 1 above, the product implementing the present invention (Sample No. 2) has a low melting point, and therefore, as is clear from the results of the brazing test, it is not suitable for joining members containing AC4C, etc. It was confirmed that a sufficient and good fillet could be formed at the joint and excellent brazing properties could be achieved.

Moreover, the natural electrode potential is also a relatively important factor, and therefore, it could be expected that the corrosion of the brazed joint would be suppressed. On the other hand, No. without Cu addition
No. 3 had a low natural electrode potential, and conventional No. 4 had a high melting point and was virtually impossible to braze.

In addition to the compositions listed in the table above, Aρ8wt%S
i -20wt%Z n-0,5wt%Cu5AJJ-
10wt%S i -50wt%Zn -1,0wt
%Cu and Al2-5wt%S i -'(Owt%Z
When the same test as above was carried out for n-1.5wt%Cu, low solidus and liquidus temperatures and good brazing conditions were obtained, and the natural electrode potential also showed a relative influence. It was something. In addition, sample No. 2 in Table 1
0. Similar tests were conducted by adding 5 wt% Be and also adding 0.8 wt% Be to the brazing filler metal with the above composition, and found that there was almost no effect on the solidus and liquidus temperatures and the natural electrode potential. tensile strength, without giving
The effect of improving mechanical properties such as elongation was observed.

that's all 1

Claims (1)

[Claims] Si: 4 to 12 wt%, Zn: 15 to 55 wt%, Cu
:0.2 to 2.0 wt%, with the remainder being aluminum and unavoidable impurities.