JPH07303982A - Aluminum alloy material for non-corrosion flux brazing and brazing method thereof - Google Patents

Abstract

PURPOSE:To provide the aluminum alloy material and preferable brazing method thereof to suitably braze at low cost by using non-corrosion flux, metal powder, etc. CONSTITUTION:The material, part of which is alloyed with a metal to be melted and formed to a brazing filler metal, contains, by weight, one or two kinds among 0.4-1.6% Si, 0.4-3.0% Cu, further Mg is controlled to <=0.2%.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an aluminum alloy material for brazing non-corrosive flux and a brazing method, for example, by using non-corrosive flux and silicon, suitable brazing can be performed at low cost. It is intended to provide an aluminum alloy material for brazing and to propose a preferable brazing method thereof.

[0002]

2. Description of the Related Art Forming a device by brazing aluminum or an aluminum alloy material has been widely adopted since it has advantages such as light weight and heat conductivity that cannot be obtained from other metal materials. In particular, in a heat exchanger for vehicles, a fin material brazed to a tube material is generally used.

However, in the brazing using the aluminum or aluminum alloy material as described above, the method of adding and supplying the brazing material and the flux to the joint portion respectively to heat the brazing material is complicated in the operation and the cost is high. Moreover, because of disadvantages such as poor brazing and uneven brazing quality, it has been widely adopted to use a brazing sheet in which a brazing material and a skin material layer are clad as a core material. That is, the brazing is achieved all at once by charging the brazing material layer into the furnace in a combined state so as to be joined to the mating member and heating.

However, in recent years, some proposals have been made for brazing without using the above-mentioned clad material, and one of such methods is a non-corrosive fluoride flux based on potassium aluminum fluoride. Patented to braze with a mixture of metal powder and metallic silicon powder
It was published in issue 5100048. That is, according to this method, the silicon applied to the surface of the aluminum material rapidly diffuses into the aluminum material at the brazing temperature, and melts when the surface layer of the aluminum material approaches the Al-Si eutectic composition (eutectic temperature: 577).
C.), and the components are joined together by soldering.

Specifically, a mixture of a fluoride-based flux and metallic silicon powder is applied by being suspended in dry powder or a volatile liquid such as water or alcohol, and the mixture is mixed in a weight ratio of 0.1 to 3: The coating amount of the mixture is about 5 to 30
g / m ² , brazing temperature is 577 ° C or higher, and the time is 2 to 5
However, the optimum condition is to apply a mixture of about 30% silicon in an amount of 20 to 30 g / m ² and use a pure brazing material.
Al material and Al-1% Mn material are shown.

[0006]

The method according to US Pat. No. 5100048 as described above has a great advantage in terms of process and cost since it is not necessary to use it as a clad material, and also in terms of material utilization such as scrap reuse. However, it is difficult to evenly apply the mixture of non-corrosive flux and metallic silicon to the surface of the aluminum material, and in the case where it is partially unevenly applied, The aluminum material locally largely dissolves in a portion where a large amount of silicon powder adheres. For this reason, the remaining thickness of the aluminum material after brazing becomes non-uniform, resulting in a decrease in strength and a corrosion period, and in some cases, a through hole is generated.

[0007]

As a result of repeated studies on solving the problems in the prior art as described above, the present invention has revealed that the diffusion rate of silicon into Al is delayed so that the silicon and aluminum materials can be separated from each other. Local melting at the same time is reduced, and while forming an appropriate fillet, while avoiding large local melting of aluminum material, the melting depth is made uniform and the brazing with improved joining condition is obtained accurately. It succeeded in, and is as follows.

(1) Partly alloys with a metal and melts,
A material for forming a brazing filler metal, wherein Si is 0.4 to 1.
6%, Cu: 0.4 to 3.0% of at least any one or two kinds, and Mg is regulated to 0.2% or less, non-corrosive flux brazing aluminum Alloy material.

(2) The aluminum alloy material for brazing non-corrosive flux according to the item (1), wherein the metal is silicon or another metal.

(3) The non-corrosive flux brazing aluminum alloy material according to the above (1) or (2), wherein the metal is metal silicon powder or metal silicon powder and other metal powder.

(4) wt%, Si: 0.4 to 1.6%, Cu:
A non-corrosive flux and a metal are used for an aluminum alloy member containing at least one or two of 0.4 to 3.0% and Mg regulated to 0.2% or less. A non-corrosive flux brazing method for an aluminum alloy material, which comprises alloying and melting a part of the aluminum member to form a braze, and brazing.

(5) The non-corrosive flux brazing method for an aluminum alloy material as described in the above item (4), wherein the metal is silicon or other metal.

(6) The method for brazing a non-corrosive flux of an aluminum alloy material according to the above (4) or (5), wherein the metal is metal silicon powder or metal silicon powder and another metal powder. .

[0014]

[Function] The non-corrosive flux used in the present invention is LiF, Na
F, KF, CaF, AlF ₃ , SiF _4, etc., a powder mixture of fluorides, or a powder obtained by melting these, or a complex compound of the above fluorides, such as KAlF ₄ , K ₂ AlF ₅ , K ₃ AlF ₆ , K ₂
A simple substance or a mixture of SiF ₆ or the like, or a powder obtained by melting these, or the like, and none of such fluoride-based fluxes have corrosiveness to aluminum as chlorides do. The average powder size of this product is 0.1-
About 30 μm, preferably 1 to 10 μm on average
Is.

Metals that form a braze by alloying with the skin material and melting, include zinc in addition to silicon, and also contain Zn,
Preferred is a silicon-zinc alloy containing 10 to 30% Zn. Such a metal may be formed as a brazed member, for example, may be sprayed on the tube surface of a heat exchanger, or may be powdered, and the powder is applied to the brazed member or mixed with the flux powder. It may be applied as a slurry. In this case, 10 to 30% zinc powder or 2 to 20% copper powder may be added and mixed and coated in addition to the silicon powder. Particularly, alloying silicon to be supplied to the brazed member in advance has a disadvantage that the cost is high, and thermal spraying is a thermal spraying material, and there is a disadvantage due to thermal spraying. It is applied to and used. Of these, silicon is preferable because it easily forms an Al-Si eutectic alloy at the brazing temperature.

The reaction mechanism of the brazing method as described above can be analyzed in the following process, when it is specifically shown by using metallic silicon powder and potassium aluminum fluoride eutectic non-corrosive flux. Melting of non-corrosive aluminum potassium fluoride based flux at around 562 ° C Destruction of the oxide film on the surface of aluminum material Diffusion of Si into the surface layer of aluminum material The surface layer with a high Si concentration starts melting at the Al-Si eutectic temperature ( 577 ° C) Al-Si eutectic melt is generated while melting the aluminum material until the metallic silicon powder is completely extinguished. The eutectic melt acts as a brazing filler metal and flows into the joint to form a fillet (up to about 600 ° C) Cooling thereafter Fillet solidifies during the process and brazing is complete

Si: 0.4 to 1.6%, Cu: 0.4 to 3.0%, either one or two. The above-mentioned reactions (1), that is, the diffusion of Si into the aluminum brazing member, occurs in a short time, so if the metallic silicon powder is non-uniformly adhered, local melting of the aluminum material occurs remarkably in a large amount of the metal silicon powder. Become. By containing an appropriate amount of Si and / or Cu in the aluminum member, the diffusion rate of silicon is delayed, and the diffusion is evenly performed during that time, local melting of such aluminum material is reduced, and the remaining plate Eliminates uneven thickness. In this case, if Si is less than 0.4%, its effect is poor, while if it exceeds 1.6%, burning occurs at the Al-Si eutectic temperature. Further, if the Cu content is less than 0.4%, its effect is insufficient, while if it exceeds 3.0%, burning occurs at the brazing temperature, and if it is set to 0.4 to 3.0%, those The diffusion rate is reduced without any disadvantage.

The strength of the Al member after brazing can be increased by setting Si and Cu in the above range, and those which do not reach this range have insufficient action. In addition to Si and Cu, Fe, Mn, Cr and the like can be contained.

Mg: 0.2% or less. Even if a small amount of Mg enhances the strength after brazing, when brazing with a non-corrosive fluoride-based flux, the flux components F and Mg react to reduce the action of the flux, resulting in brazing properties. Is significantly reduced. By limiting the amount to 0.2% or less, such a reaction between F and Mg is limited, and an effective flux action is secured. The above-mentioned circumstances are the same not only for metallic silicon powder but also for silicon alloy powder or thermal spraying.

The alloy material of the present invention is rolled and formed, for example, cut into a predetermined size and formed into a fin material, or formed and welded into a pipe material, or extruded into a brazed member. It By doing so, the following advantages can be obtained. (a) There is no complication of melting and brazing a brazing material containing Si. (b) That is, since the aluminum alloy material of the present invention is not a clad material provided with a brazing material layer, it is possible to prevent die wear during molding. (c) Further, since Si from the brazing material is not mixed in the scrap during rolling and forming, it can be reused.

[0021]

EXAMPLES The inventors of the present invention produced DC alloy castings of aluminum alloys according to the present invention and comparative examples as shown in the following Table 1 by a conventional method, rolled and annealed to produce an annealed plate having a thickness of 1.0 mm. did. No. 1, No. 2 and No. 4 contained Si within the scope of the present invention, while No. 3 contained Si and Cu within the scope of the present invention, and No. 5 and No. 6.6 contains Cu in the scope of the present invention. No.7 and No.8 are Si and Cu
None of them reached the range of the present invention, and No. 9 contained Mg in the range of the present invention or more.

[0022]

[Table 1]

An average grain size of 10 was obtained for each test piece having a width of 30 mm and a length of 50 mm cut out from each of the above-mentioned annealed plates.
A mixture of 100 μm or less aluminum fluoride potassium eutectic flux and metallic silicon powder with a particle size of 10-80 μm (weight ratio 2: 1) is suspended in 400 g of pure water, and the test piece is degreased and sprayed on one side. And then heated at 150 ° C. for 5 minutes to dry. When the surface of the test piece after drying was visually observed, the adhering state of the mixture was quite uneven. The average coating amount of the mixture was found to be 24 to 29 g / m ^{2 as} a result of measuring the weight of the test piece before and after coating.

The brazing test was carried out on the surface coated with the mixture as described above, with a thickness of 0.5 mm, a width of 25 mm and a length of 3 mm.
An inverted T-shaped test piece in which the 003-H14 material was vertically stood was assembled, and the temperature rising rate was 50 ° C./min at 600 in a nitrogen gas atmosphere.
The brazing is performed by heating for 3 minutes at ℃, the test piece after brazing is cut perpendicular to the joint, embedded in resin, and the cross section is polished to obtain the maximum remaining thickness of the specimen. And the minimum value was measured, and the erosion depth of each was calculated from the difference from the plate thickness. Further, the results of visually observing the state of fillet formation at the joint were as shown in Table 2 below. Note that the remaining thickness of the test material was particularly small, that is, the location where it was melted deeper than the other portions corresponded to the location where a large amount of the mixture locally adhered before brazing.

[0025]

[Table 2]

That is, the maximum erosion depth of the example of the present invention is 33 to 59 μm, which is considerably smaller than the comparative example of 73 to 85 μm, and the difference between the maximum and the minimum is 1 in the example of the present invention.
It was also confirmed that the present invention is good and the brazing conditions are all favorable even in the joined state in which the bonding state is 1 to 37 μm, which is significantly reduced from the comparative example of 53 to 64 μm.

[0027]

As described above, according to the present invention, no special clad material is prepared, and a large amount of melting locally in the aluminum material is avoided so that the remaining thickness is uniform and at a low cost. It is an invention that has a great effect industrially because it is capable of appropriately forming brazing excellent in quality.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI technical display location B23K 35/363 H C22C 21/12

Claims (6)

[Claims] 1. A material which is partially alloyed with a metal and melted to form a brazing filler metal, wherein the wt% is Si: 0.4 to 1.6%,
Cu: A non-corrosive flux brazing aluminum alloy material containing at least any one or two kinds of 0.4 to 3.0% and controlling Mg to 0.2% or less. 2. The aluminum alloy material for non-corrosive flux brazing according to claim 1, wherein the metal is silicon or silicon and another metal. 3. The non-corrosive flux brazing aluminum alloy material according to claim 1 or 2, wherein the metal is metal silicon powder or metal silicon powder and another metal powder. 4. In wt%, Si: 0.4-1.6%, Cu: 0.4-
A non-corrosive flux and a metal are used for an aluminum alloy member containing at least any one kind or two kinds of 3.0% and having a Mg content controlled to 0.2% or less. A non-corrosive flux brazing method for an aluminum alloy material, which comprises alloying and melting a part of the alloy to form a braze. 5. The non-corrosive flux brazing method for an aluminum alloy material according to claim 4, wherein the metal is silicon or other metal. 6. The non-corrosive flux brazing method for an aluminum alloy material according to claim 4 or 5, wherein the metal is metal silicon powder or metal silicon powder and another metal powder.