JP3224440B2 - Aluminum alloy brazing material for heat exchanger brazing and aluminum alloy brazing sheet for heat exchanger - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an aluminum alloy brazing material and a brazing sheet used for brazing a heat exchanger, and is particularly suitable for a heat exchanger used in a severe corrosive environment such as an automobile. .

[0002]

2. Description of the Related Art In general, most heat exchangers made of aluminum alloy used for automobiles and the like are manufactured by vacuum brazing or flux brazing using fluoride or the like. In these brazing, as defined in JIS Z 3263, Al-Si alloys represented by BA4343 and BA4045, BA4004 and BA4005
Al-Mg-Si-based brazing filler metals are typically used, and brazing sheets obtained by cladding these brazing filler metals with a core material made of an Al-Mn-based alloy are often used. At the time of brazing, these materials are heated to a temperature of 590 to 615 ° C. corresponding to a temperature between a solidus line and a liquidus line of the brazing material, and joined in a state where the brazing material flows appropriately. are doing.

[0003]

However, with the recent demand for thinner materials, demands for higher strength have been increasing. In order to increase the material strength, Mg, Si, and Cu have been added to the material.
Etc. tend to be added more. However, when the addition amount of these elements is increased, the strength of the material is improved, but the melting point (solidus temperature) is lowered, and the material is locally melted or buckled at the brazing temperature as described above. There is. In order to cope with this, it is conceivable to use a brazing material such as BA4045 or 4047 having a high Si content and a relatively low brazing temperature, but the brazing temperature is slightly reduced, and Mg, An increase in the amount of Si, Cu, etc. cannot be expected to be large. In addition, the difference between the solidus temperature and the liquidus temperature of this brazing material is extremely small, and strict temperature control is required to obtain appropriate fluidity at this temperature, making it unsuitable for mass production. However, practical application is difficult.

An Al—Si brazing material containing a large amount of Cu (about several wt%) so as to further lower the melting point (BA414)
5) is also known, but is not suitable for materials used under severe corrosive environments such as heat exchangers for automobiles because of poor corrosion resistance. Further, the above-mentioned Cu-containing brazing material is:
Although the decrease of the melting point is large, excessive reduction of the melting point is not preferable in brazing. Heat exchangers for automobiles and the like are mainly brazed in vacuum using a brazing material containing Mg or brazed in an inert atmosphere using a flux based on fluoride. In the former, Mg evaporates during brazing, destroying the oxide film of the brazing material, trapping the oxidizing gas in the atmosphere to prevent re-oxidation of the surface, and enabling brazing. It melts and destroys the oxide film, enabling brazing. If the melting point of the brazing material is too low, the brazing will be melted before these Mg and flux act, making sound brazing impossible. Therefore, in order to braze a high-strength Al alloy satisfactorily, a brazing material having a melting point at an appropriate temperature and having a sufficiently large temperature difference between the solidus line and the liquidus line is desired. The present invention has been made in view of the above circumstances, and provides a brazing material having a suitably low melting point, easy temperature control, and excellent corrosion resistance, and further comprising a brazing material obtained by cladding the brazing material with a high-strength base material. The purpose is to provide a sheet.

[0005]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the aluminum alloy brazing material for brazing a heat exchanger of the present invention has a Si content of 5 to 15% and a Cu content of 0.1 to 1% by weight.
%, Zn: 0.5 to 8%, with the balance being Al and unavoidable impurities. The aluminum alloy brazing material for brazing a heat exchanger according to the second invention has a Si content of 5 to 15% by weight,
Mg: 0.2-2%, Cu: 0.1-1%, Zn: 0.
5 to 8%, with the balance being Al and unavoidable impurities. The brazing filler metals according to the first and second aspects of the present invention further include Bi: 0.01 to 0.2% and Be: 0.0002 by weight%.
One or two of 0.0015%, In: 0.005
-0.1%, Sn: 0.05-0.2%, Pb: 0.0
0.5 to 0.2%, one or more of Ga: 0.005 to 0.2%, Na: 0.005 to 0.2%, K: 0.
005-0.2%, Ca: 0.005-0.2%, Sr
: One or two or more of 0.005 to 0.2% can be contained.

Further, the aluminum alloy brazing sheet for a heat exchanger of the present invention has a Mn: 0.5-0.5% by weight.
1.5%, Si: 0.5 to 1.5%, Cu: 0.3 to
The brazing material according to any one of the above is clad on one or both surfaces of a core material containing 0.8%, with the balance being Al and unavoidable impurities. Furthermore, the aluminum alloy brazing sheet for a heat exchanger of another invention is:
By weight%, Mn: 0.5-1.5%, Si: 0.5-
1.5%, Cu: 0.3-0.8%,
Mg: 0.05-3%, Zr: 0.05-0.25%,
Cr: 0.05-0.25%, Ti: 0.05-0.2
5%, V: 0.05 to 0.25% of one or two or more kinds, the balance being made of Al and unavoidable impurities, on one or both sides of a core material, It is characterized by being clad. The brazing sheet in which the brazing material is clad on one surface of the core material includes a material in which another material, for example, a sacrificial anode material is clad on the other surface.

[0007]

In other words, according to the brazing material of the present invention, since a proper amount of Si, Cu and Zn is basically contained, a sufficient width is provided between the solidus temperature and the liquidus temperature. The melting point can be lowered appropriately while the alloy is kept in place, and a high-strength Al alloy having a low melting point can be satisfactorily brazed. In addition, the brazing material has extremely excellent corrosion resistance due to the combination of Cu and Zn, and is suitable for use in applications where the corrosive environment is severe. According to the brazing sheet in which the brazing material is clad with a high-strength Al alloy core material, the above-mentioned action can be obtained by the brazing material, and a high-strength Al alloy brazed product can be easily obtained. Next, the reasons for limiting the components of the brazing material and the brazing sheet of the present invention will be described together with specific actions.

(Brazing material) Si: 5 to 15% Si is added to lower the liquidus temperature of Al and increase the fluidity during melting. However, if the Si content is less than 5%, the liquidus temperature of the brazing filler metal is too high, and the fluidity during melting decreases. If it exceeds 15%, the eutectic point is exceeded and the liquidus temperature increases with an increase in the Si content, and the fluidity decreases as in the case where the Si content is insufficient. In addition, it is desirable to set it to 7 to 11% for the same reason. Cu: 0.1-1% Cu is added to lower the solidus temperature of the Al-Si alloy. If the content is less than 0.1%, the effect is insufficient, and the self-corrosion rate becomes too large. Also, 1
%, The pitting corrosion resistance of the brazing material is reduced and the potential becomes noble, thereby impairing the corrosion resistance of the surrounding brazed products. In addition, the solidus temperature of the brazing material is too low, so that good brazing cannot be performed. Zn: 0.5 to 8% Zn is added together with Cu to lower the solidus temperature of the brazing material. In addition, since Zn makes the electric potential a base side, the corrosion resistance of the brazing material itself and surrounding members is remarkably improved by an appropriate combination with Cu which makes the electric potential noble.
However, when the content of Zn is less than 0.5%, the effect of lowering the solidus temperature is insufficient, and the pitting corrosion resistance of the brazing material is reduced. Further, since the potential of the brazing material becomes noble, the corrosion resistance of the surrounding members is reduced, and the corrosion proceeds. On the other hand, 8%
If it exceeds 300, self-corrosion of the brazing filler metal becomes too large, so the above range is set. In addition, it is desirable to set it in the range of 3-6% for the same reason. Mg: 0.2 to 2% Mg evaporates from the material into the furnace during vacuum brazing and reacts with the oxidizing gas in the furnace to prevent oxidation of the material and improve brazing properties. Add in case of vacuum brazing. 0.
If it is less than 2%, the above effect is insufficient, and if it exceeds 2%, not only no further effect can be expected, but also furnace contamination becomes remarkable.

Bi: 0.01-0.2%, Be: 0.0
Since 002 to 0.0015% each improve the flowability and the filling property of the brazing material in vacuum brazing and improve the brazing property, one or more kinds are added selectively in the brazing material containing Mg. Below the lower limits, the above effects are insufficient, and above the upper limits, the aluminum alloy to be brazed is eroded. In: 0.005 to 0.1%, Sn: 0.05 to 0.2
% Pb: 0.005 to 0.2%, Ga: 0.005 to 0.
In order to make the potential of the brazing material 2% lower and impart sacrificial anode properties to improve the corrosion resistance of the brazed article, one or more kinds are selectively added. If each content is less than the lower limit, the effect is insufficient, and if it exceeds the upper limit, self-corrosion becomes severe. Na: 0.005 to 0.2%, K: 0.005 to 0.2
% Ca: 0.005 to 0.2%, Sr: 0.005 to 0.
Each of 2% is selectively added in order to refine the structure to improve the fluidity and improve the brazing property. If the respective amounts are less than the lower limits, the effect is insufficient, and if it exceeds the upper limit, further effects cannot be expected.

(Core material for brazing sheet) Since the brazing material is used for the skin material of the brazing sheet, only the core material will be described here. Mn: 0.5 to 1.5% Mn precipitates as an Al-Mn-based or Al-Mn-Si-based compound to improve pitting corrosion resistance and strength. If the content of Mn is less than 0.5%, the effect is insufficient, while if it exceeds 1.5%, the workability is reduced, so that the above range is set. Si: 0.5 to 1.5% Precipitates as an Al-Mn-Si-based compound and solid-dissolves in a base material to improve the strength. If it is less than 0.5%, the improvement in strength is insufficient, and If it exceeds 1.5%, the corrosion resistance is reduced, so the above range is set. Cu: 0.3-0.8% solid solution in the base material to improve the strength and increase the noble potential to improve the pitting resistance. If it is less than 0.3%, the above effect cannot be sufficiently obtained, and if it exceeds 0.8%, it becomes too noble to lower the corrosion resistance of peripheral members.

Mg: 0.05-3%, Zr: 0.05-0.25% Cr: 0.05-0.25%, Ti: 0.05-0.2
5% V: 0.05 to 0.25% Mg precipitates as Mg ₂ Si in the coexistence with Si, and Cr,
Zr and V form a compound with Al to improve the strength. Since Ti improves the corrosion resistance, one or more of these are selectively added. If these are below the lower limit,
If the respective effects are insufficient, and if the upper limit is exceeded, the corrosion resistance decreases with Mg and the workability decreases with other elements.

[0012]

EXAMPLE A brazing sheet having a thickness of 0.5 mm was formed by cladding a brazing material shown in Table 2 on both sides of a core material having the composition shown in Table 1 with a thickness of 10%. In addition, Al brazing material, Al equivalent to JIS BA4045 and BA4145, was used as a comparative material.
An alloy was prepared. This brazing sheet 1 (50 ×
25 mm), as shown in FIG. 1, is vertically set on a JIS A 3003 alloy plate 2 having a thickness of 2 mm, and a SUS 304 wire 3 having a diameter of 2 mm is arranged at one end of an abutting portion thereof. With a slight inclination,
It was assembled with the alloy plate 2 in a T-shape. And M in the brazing material
For brazing sheets containing no g, a fluoride-based flux is applied and the N ₂ atmosphere is applied to the brazing material.
10 ⁻⁴ to for brazing sheet containing
Brazing was performed at a predetermined temperature for 5 minutes in a vacuum of rr, and the filling length of the brazing material 4 in the gap between the brazing sheet 1 and the alloy plate 2 was measured to evaluate the brazing property. The heating temperature was the temperature between the solidus and liquidus of each brazing material.

Each of the brazing sheets is made of the inventive material and the comparative material No. No. 11 at 575 ° C .;
10 was heated at 600 ° C. for 5 minutes, and then subjected to strength measurement, and further subjected to a salt spray test for 2,000 hours to measure the pit depth. The results of these measurements are shown in Table 3. As is clear from the table, the inventive material is excellent in brazing properties and corrosion resistance, and has a large temperature difference between the solidus and liquidus lines, and facilitates temperature control. In addition, comparative material No. 9
In Comparative Material No. 2, the brazing temperature was too low, but the brazing did not melt. In No. 10, the brazing material eroded into the core material because the core material was locally melted, resulting in poor brazing.

[0014]

[Table 1]

[0015]

[Table 2]

[0016]

[Table 3]

[0017]

As described above, according to the aluminum alloy brazing material for brazing a heat exchanger of the present invention, a predetermined amount of S
Since i, Cu, Zn or Mg are used as basic components and optional components are added as desired, the melting point can be lowered appropriately while the temperature difference between the solid and liquidus lines is kept sufficiently large. Even with a high-strength Al alloy, good joining can be achieved without local melting or the like. In addition, since a sufficient temperature difference between the solid and liquidus lines can be obtained, temperature control is easy and work efficiency is improved. Furthermore, the brazing material has excellent corrosion resistance and can be used for applications in severe corrosive environments. Further, according to the aluminum alloy brazing sheet for a heat exchanger of the present invention, since the above brazing material is clad with a high strength Al alloy as a core material, a high strength brazed product having the above characteristics can be obtained efficiently.

[Brief description of the drawings]

FIG. 1 is a front view showing a brazing characteristic test of a brazing sheet according to an embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Brazing sheet 2 Al alloy plate 4 Brazing

────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁷ Identification code FI C22C 21/02 C22C 21/02 (56) References JP-A-3-291160 (JP, A) JP-A-3-230890 (JP) JP-A-3-57588 (JP, A) JP-A-59-100249 (JP, A) JP-A-2-175093 (JP, A) JP-A-4-193926 (JP, A) (58) Field surveyed (Int. Cl. ⁷ , DB name) B23K 35/22-35/28 C22C 21/00-21/18

Claims (7)

(57) [Claims] 1. Si: 5 to 15% by weight, Cu: by weight%
0.1-1%, Zn: 0.5-8%, the balance being A
aluminum alloy brazing material for heat exchanger brazing consisting of l and unavoidable impurities 2. Si: 5 to 15% by weight, Mg:
0.2-2%, Cu: 0.1-1%, Zn: 0.5-8
% Brazing material for heat exchanger brazing, containing Al and inevitable impurities 3. The composition according to claim 2, further comprising:
Bi: 0.01-0.2%, Be: 0.0002-0.
Aluminum alloy brazing filler metal for brazing of heat exchanger containing one or two kinds of 0015% 4. In addition to the components according to claim 1, In: 0.005 to 0.1% of Sn, Sn:
0.05-0.2%, Pb: 0.005-0.2%, G
a: Aluminum alloy brazing material for heat exchanger brazing containing one or more of 0.005 to 0.2% 5. In addition to the components according to claim 1, Na: 0.005 to 0.2% by weight, K:
0.005 to 0.2%, Ca: 0.005 to 0.2%,
Sr: Aluminum alloy brazing filler metal for brazing a heat exchanger containing one or more of 0.005 to 0.2%. 6. Mn: 0.5-1.5% by weight, S
i: 0.5 to 1.5%, Cu: 0.3 to 0.8%, with the balance being on one or both sides of a core material comprising Al and unavoidable impurities. Alloy brazing sheet for heat exchangers clad with the brazing material described in 1 above 7. Mn: 0.5-1.5% by weight, S
i: 0.5-1.5%, Cu: 0.3-0.8%, Mg: 0.05-3%, Zr: 0.05-
0.25%, Cr: 0.05 to 0.25%, Ti: 0.
One or both surfaces of a core material containing one or more of 0.05 to 0.25% and V: 0.05 to 0.25%, and the balance being Al and unavoidable impurities. Aluminum brazing sheet for heat exchanger clad with brazing material according to any of the above