JPH074662B2 - Brazing method for Al and Al alloy members - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a brazing method for Al and Al alloy members, which has particularly excellent brazing properties and strength and has improved paintability after brazing.

[0002]

2. Description of the Related Art Generally, there are radiators, heaters, oil coolers, condensers, evaporators, etc. as heat exchangers for automobiles, of which the oil coolers, condensers, and evaporators are mostly made of aluminum, and some of the radiators and heaters are made of aluminum. Has been done. Such an aluminum heat exchanger is constructed by using an aluminum brazing sheet shown in Table 1 and a member made of an Al alloy shown in Table 2, and is generally manufactured by a brazing method.

[0003]

[Table 1]

[0004]

[Table 2]

As a brazing method, an in-furnace brazing method using a chloride flux (hereinafter abbreviated as FB method) and a vacuum brazing method without a flux (hereinafter abbreviated as VB method) have been mainly used. Then, a method of brazing in a non-oxidizing atmosphere using a non-corrosive fluoride-based flux (hereinafter abbreviated as NB method) has come to be adopted, and it is mainly used for manufacturing radiators and capacitors for automobiles. There is. In the present specification,% of Al alloy composition means wt%.

[0006]

Aluminum heat exchangers by the brazing method, particularly automobile heat exchangers, have been required to be thin in view of reduction in manufacturing cost and weight reduction. As shown in FIG. 5, a radiator made of all-aluminum is usually a tank (1), a plate (2), a side bracket (3) having a U-shaped cross section, and a flat tube (4).
And the fins (5), and the engaging portion (13) of the side bracket (3) is connected to the core plate (2).
It is the side bracket that requires the most strength among these members. This has the function of attaching the radiator to the vehicle body, and is generally used in JIS3003.
(Cu: 0.05 to 0.20%, Mn: 1.0 to 1.5%, Al residue)
In the brazing sheet using the core material, the strength after brazing is only about 11 kg / mm ² in tensile strength, and the strength is insufficient for thinning.

For this reason, the core material JIS3004 (Mn:
1.0-1.5%, Mg: 0.80-1.3%, balance Al), 695
1 (Si: 0.2 to 0.5%, Cu: 0.15 to 0.40%, Mg:
0.4-0.8%, balance Al), 7N01 (Mn: 0.2-0.7)
%, Mg: 1.0 to 2.0%, Zn: 4.0 to 5.0%, balance A
Attempts have been made to use Mg-containing alloys such as l). For example, JIS 7N01 is annealed by air cooling after brazing and has a tensile strength of about 35 kg / mm ² by natural aging.

However, as shown in FIG. 6, JIS7N01 is used as the core material (7), and the Al-Si type brazing material (8) is provided on one surface thereof.
As shown in FIG. 7, a brazing sheet (6) clad with is laid vertically on a substrate (9) made of JIS 1050 (Al with a purity of 99.50% or more), and a fluoride flux is applied to it in a non-oxidizing atmosphere. When brazing (NB method),
Fillet does not form. This also applies to the FB method. Furthermore, a cotton-like substance is generated on both sides of the brazing sheet, and in the actual manufacturing of the heat exchanger, not only the cotton-like substance is scattered in the brazing furnace to contaminate the inside of the brazing furnace, but also after the brazing. There is a problem that the adhesion of the paint is deteriorated in the painting process.

As a result of various studies in view of this, the present invention has revealed that Mg
When an Al alloy containing Al is used as a core material and a brazing sheet using an Al-Si brazing material as a skin material is brazed,
Fillets are less likely to be formed because Mg in the core material and Si in the brazing material are easily bonded to each other, so that Si in the brazing material diffuses into the core material, and a cotton-like material formed on the surface of the brazing sheet. As a result of analysis, it was found that the substance was a compound in which K, Al, F, which are the flux components used in the NB method, reacted with Mg. Also, during brazing, Mg in the core material reacts with the flux in the surface layer and is taken into the flux,
Furthermore, since the Mg concentration in the surface layer of the core material decreases, Mg diffuses from the core material to the surface layer and reacts with the flux. As a result, the greater the amount of Mg in the core material, the greater the amount of reacted compounds. It was found that it occurs as a cotton-like substance.

[0010]

As a result of further investigations based on the above findings, the present invention has high strength and excellent brazing properties that enable thinning of aluminum heat exchangers brazed by the NB method, This is a method for brazing an Al alloy member having good paintability after brazing.

That is, one of the brazing methods of the present invention is a brazing sheet in which both sides of an Al alloy core material are clad with Al-Si type brazing material, and the core material is an Al alloy containing Mg, and the brazing material is used. Other aluminum and aluminum by using an aluminum brazing sheet member provided with a diffusion prevention layer made of Al or an Al alloy for preventing the diffusion of Mg and Si between the materials.
This is a brazing method for Al and Al alloy members, which comprises combining with an alloy member, applying a fluoride-based non-corrosive flux to these, and brazing in an non-oxidizing atmosphere.

Another one of the brazing methods of the present invention is Al
In a brazing sheet in which an Al-Si type brazing material is clad on one surface of an alloy core material, the core material is Al containing Mg.
As an alloy, a diffusion prevention layer made of Al or an Al alloy for preventing diffusion of Mg and Si is provided between the core material and the brazing material, and Al for preventing diffusion of Mg on the surface of the core material not clad with the brazing material or Using an aluminum brazing sheet member provided with a diffusion preventive layer made of an Al alloy, other Al and Al
This is a brazing method for Al and Al alloy members, which comprises combining with an alloy member, applying a fluoride-based non-corrosive flux to these, and brazing in an non-oxidizing atmosphere.

[0013]

In the aluminum brazing sheet used in the present invention, Mg and S are mixed between the core material containing Mg and the brazing material.
By providing a diffusion prevention layer made of Al or an Al alloy that prevents diffusion of i, Si in the brazing material and Mg in the core material
It prevents direct contact with the brazing material and improves the brazing property, and at the same time prevents the Mg in the core material from diffusing to the surface of the brazing sheet to prevent the reaction between Mg and the fluoride-based flux, thereby preventing the generation of cotton-like substances. Can be prevented.

In a brazing sheet in which a brazing material is clad on one surface of a core material containing Mg, a diffusion preventing layer of Mg and Si is provided between the core material and the brazing material, and a diffusion of Mg is carried out on the core material surface not clad with the brazing material. By providing the prevention layer, it is possible to prevent Mg in the core material from diffusing to the surface not clad with the brazing material and reacting with the fluoride-based flux. As a result, it becomes possible to use a high-strength Al alloy containing Mg as the core material of the brazing sheet, which not only makes the brazing sheet thinner, but also improves the coatability after brazing.

Further, in the aluminum brazing sheet used in the present invention, Al containing Mg as a core material is used.
As the alloy, an alloy having a melting point of 600 ° C. or higher and containing Mg, for example, JIS3004, 3005 (Mn: 1.0 to 1.5%,
Mg: 0.2-0.6%, Al remaining), 5005 (Mg: 0.5
~ 1.1%, Al remaining), 6063 (Si: 0.20-0.60%,
Mg: 0.45 to 0.90%, Al remaining), 6951, 7N01, etc. Also, as an Al-Si brazing material, the melting point is 600
Al-Si alloy below ℃, for example JIS4343 (S
i: 6.8 to 8.2%, Al remaining), 4045 (Si: 9.0 to
11.0%, Al remaining), 4047 (Si: 11.0 to 13.0%, A
l), 4145 (Si: 9.3 to 10.7%, Cu: 3.3 to
4.7%, Al residue) etc.

Further, as the diffusion prevention layer for preventing the diffusion of Mg and Si, and Mg, Al or Al alloy containing a small amount of Mg and Si, for example, JIS1xxx, 3xxx series alloys are used. An alloy having the highest possible strength within the JIS1XXX, 3XXX system, such as JIS3202 (Mn: 1.0
~ 1.5%, Al remaining), 3003, etc., and the thickness of the diffusion prevention layer must be 60 μm or more, but if it is made thicker than necessary, the strength of the brazing sheet will be reduced. It is desirable to set the thickness to.

The high-strength aluminum brazing sheet used in the present invention is suitable, for example, for a side bracket material of a radiator, but can also be used as other members such as a core plate.

According to the present invention, the high-strength aluminum brazing sheet having the above-mentioned structure is used as a member of a heat exchanger and is brazed in combination with other Al and Al alloy members. The other Al and Al alloy members are, for example, radiator fins and headers. Such an assembly is degreased with an organic solvent or the like, coated with a fluoride-based non-corrosive flux, and brazed in a non-oxidizing atmosphere. Fluoride-based flux is generally a compound containing K, Al and F as a basic composition, and KAlF ₄ , K ₂ AlF ₅ · H.
A simple substance or a mixture of ₂ O, K ₃ AlF _6, etc.

These fluxes are generally suspended in tap water to prepare a suspension having a concentration of about 1 to 10%, and applied to the assembly by spraying or dipping. Then, it is dried to evaporate the solvent water. Dry at 100-300 ° C.

A non-oxidizing atmosphere is a dew point of -30 ° C or lower,
The atmosphere has an oxygen concentration of 500 ppm or less, and is generally replaced with nitrogen gas to obtain this atmosphere. An inert gas such as argon gas may be used instead of nitrogen gas.

The assembly is inserted into the above non-oxidizing atmosphere, and is brazed by heating it in a temperature range not lower than the solidus temperature of the brazing alloy used and not higher than the solidus temperature of the core material and other members. Generally, it is carried out at a temperature of 600 ° C for about 1 minute.

[0022]

【Example】

(Example-1) As shown in FIG. 1, S was formed on both surfaces of the core material (7).
A brazing sheet (6) for use in the present invention, which comprises an annealed material having a thickness of 1.2 mm, which is obtained by clad a brazing material (8) through a diffusion prevention layer (10a) of i and Mg by a conventional method, and having a structure shown in Table 3. Was produced. These were evaluated by the following methods.

As shown in FIG. 2, it stands vertically on a substrate (9) made of JIS1050, and after degreasing trichlene vapor, K
A 10% flux suspension of a mixture of AlF ₄ and K ₂ AlF ₅ · H ₂ O was applied by the dipping method, dried at 150 ° C, and dew point replaced with nitrogen gas was -40 ° C and oxygen concentration was 100p.
It was inserted into a furnace having a non-oxidizing atmosphere of pm and held at 600 ° C. for 5 minutes for brazing. With respect to these brazing samples, the brazing conditions and the occurrence of cotton-like substances were observed as described below, and the results are also shown in Table 3.

The brazability was evaluated by observing the cross section of the joint as shown in FIG. 3, and those having a normal fillet (11) were good, those having no normal fillet (11) and those having an extremely small fillet (11). It was bad. Regarding the cotton-like substance, it was evaluated that some were generated and some were not generated at all. Regarding the strength, a JIS No. 5 test piece was prepared and subjected to a tensile test 30 days after heating with brazing, and a tensile strength of 17 kg / mm ² or more was marked with a circle, and a strength of less than that was marked with a x.
It was a mark.

[0025]

[Table 3]

As is clear from Table 3, No. 1 to No. 1 of the present invention
No. 7 has good brazability and high strength,
No cotton-like substances were found, and the results were generally good. On the other hand, Comparative Examples No. 8 to No. 9 in which the diffusion prevention layer was omitted
Also, in No. 11 of the conventional example, the brazing property was inferior and the occurrence of cotton-like substances was observed. Further, in No. 10 of the conventional example, high strength could not be obtained.

(Example 2) As shown in FIG. 4, a brazing material (8) was clad on one surface of a core material (7) with a diffusion preventing layer (10a) of Si and Mg interposed therebetween by a conventional method. An Mg diffusion preventing layer (10b) was provided on the surface that did not clad (8), and a brazing sheet (6) made of an annealed material having a thickness shown in Table 4 and having a thickness of 1.2 mm was used for the present invention. In addition, as a conventional example, for comparison, one in which the diffusion prevention layers (10a) and (10b) were not provided was also manufactured. These were brazed in the same manner as in Example 1, the presence or absence of cotton-like substances on the surface of the Mg diffusion preventing layer, and the acrylic black paint were spray-coated, and the adhesion was examined. The results are also shown in Table 4. In addition, the evaluation of the adhesiveness is represented by a mark of ◯ when it was good, and by a mark of x when it caused unevenness or blistering.

[0028]

[Table 4]

As is apparent from Table 4, the present invention example No. 12-
No. 14 did not show the generation of cotton-like substances and had good coatability. On the other hand, in No. 15 of the conventional example, generation of a cotton-like substance was recognized and the coatability was poor.

Example 3 Using 3003 alloy as a core material,
4045 brazing material on one side and 7072 alloy on each side 10%
An annealed material having a plate thickness of 1.5 mm and a H14 strip material having a thickness of 0.4 mm were prepared by a conventional method. A 1.5 mm material was press-molded into a header, and a 0.4 mm material was brazed on the outer surface to produce a flat tube material by ERW pipe processing. Also Al-
Thickness of tempered H14 made of 1.1% Mn-1.5% Zn alloy
A 0.12 mm strip was manufactured by a conventional method, and was corrugated to form a fin. Further, as shown in Table 5, a core material made of 7N01 alloy has a Si and Mg diffusion prevention layer made of 3003 alloy and a 4045 brazing material on one side, and a Mg diffusion prevention layer made of 3003 alloy on the other side is 10% clad. Thickness 1.2mm
A brazing sheet of the annealed material was prepared by a conventional method and pressed into a U-shaped cross section to prepare a side bracket of a radiator. In addition, as a comparative example, 4 on one side of 7N01 alloy
A brazing sheet having a plate thickness of 1.2 mm in which 10% of 045 brazing material was clad was also prepared and similarly pressed to form a side bracket for comparison.

Using these members, the radiator shown in FIG. 5 was assembled. Then, in the same manner as in (Example-1), a non-corrosive flux was applied and brazing was performed in a non-oxidizing atmosphere to manufacture an aluminum radiator. These radiators were tested for brazing property, generation of cotton-like substances, and mounted on the vehicle body for durability test by vibration. The results are also shown in Table 5.

[0032]

[Table 5]

In Inventive Example No. 16, the brazing property was good, no cotton-like substance was generated, the coatability was good, and the durability was also good. On the other hand, in Comparative Example No. 17 having no Mg diffusion preventing layer, the brazing property was poor and the durability was poor, and the cotton-like substance was generated, and the coatability was poor.

[0034]

As described above, according to the present invention, Al and A
It is possible to provide a brazing method having a high strength, an excellent brazing property, and a good coating property in the brazing of a 1-alloy member, and it is possible to achieve a remarkable industrial effect such that the brazing sheet can be thinned.

[Brief description of drawings]

FIG. 1 is a side sectional view showing an example of an aluminum brazing sheet used in the present invention.

FIG. 2 is an explanatory diagram of a brazing test.

FIG. 3 is a side sectional view showing a fillet formation state in a brazing test.

FIG. 4 is a side sectional view showing another example of the aluminum brazing sheet used in the present invention.

FIG. 5 is an explanatory diagram showing an example of a radiator core.

FIG. 6 is a side sectional view showing an example of a conventional aluminum brazing sheet.

FIG. 7 is an explanatory diagram of a brazing test.

[Explanation of symbols]

 1 tank 2 plate 3 side bracket 4 flat tube 5 fins 6 brazing sheet 7 core material 8 brazing material 9 substrate 10a Mg and Si diffusion prevention layer 10b Mg diffusion prevention layer 11 fillet 13 locking part

Claims (2)

[Claims] 1. A brazing sheet in which an Al-Si based brazing material is clad on both sides of an Al alloy core material, the core material is an Al alloy containing Mg, and the Mg alloy is interposed between the core material and the brazing material.
And other Al and Al alloy members using an aluminum brazing sheet member provided with a diffusion preventing layer made of Al or Al alloy for preventing diffusion of Si and Si, and applying a non-corrosive fluoride-based flux to them. A brazing method for Al and Al alloy members, which comprises brazing in a non-oxidizing atmosphere. 2. A brazing sheet in which an Al—Si based brazing material is clad on one surface of an Al alloy core material, the core material is an Al alloy containing Mg, and the Mg is interposed between the core material and the brazing material.
A diffusion prevention layer made of Al or an Al alloy for preventing the diffusion of Si and Si is provided, and M is formed on the surface of the core material not clad with the brazing material.
An aluminum brazing sheet member provided with a diffusion preventing layer made of Al or an Al alloy for preventing the diffusion of g is combined with other Al and Al alloy members, and a non-corrosive fluoride-based flux is applied to these, A brazing method for Al and Al alloy members, which comprises brazing in an oxidizing atmosphere.