JP2001179482A - Member brazed by aluminum alloy composite material for brazing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the durability and corrosion resistance of a member to be brazed by an aluminum alloy composite material, such as a radiator core and moreover to provide the member brazed by an aluminum alloy composite material for brazing excellent in the brazability itself. SOLUTION: This aluminum alloy composite material has the aluminum alloy core material having a composition in which the content of Mg is controlled to, by weight, <=0.1%, containing <=0.2% Fe, >0.2 to 1.0% Cu, 0.2 to 1.3% Si, 0.3 to 1.5% Mn and 0.02 to 0.3% Ti, in which the total of Cu and Si is controlled to 0.7 to 1.5%, and the balance Al with inevitable impurities, an Al-Si based brazing filler metal formed on one side of the core material and an aluminum alloy surface material formed on the other side of the core material and containing 0.3 to 3% Mg, >2 to 5% Zn and <=1.0% Si, and the balance Al with inevitable impurities. Then, in the member after brazing, the major axis of the crystal grains in the parallel cross-section of the core material after brazing is 100 μm or more.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a member brazed with an aluminum alloy composite material for brazing suitable for use as a radiator of an automobile, a tube of a heater core, and the like, and has excellent brazing properties, durability and corrosion resistance. The present invention relates to a brazing aluminum alloy composite material, that is, a member assembled with a brazing sheet.

[0002]

2. Description of the Related Art Conventionally, aluminum alloy composite materials for brazing used for tubes and the like of radiators of automobiles are Al.
-A brazing sheet in which a Mn-based 3003 alloy was used as a core material, an Al-Si-based brazing material was laminated on one surface, and an Al-Zn-based 7072 alloy was laminated on the other surface. However, JIS3
In the brazing sheet using the 003 alloy as a core material, the strength after brazing is about 110 N / mm ² , and sufficient strength cannot be obtained. Therefore, in order to prevent a decrease in the durability of a radiator using the brazing sheet, it is necessary to increase the thickness of the brazing sheet, and it has been difficult to reduce the weight of the radiator. Further, a core material using this aluminum alloy cannot be said to have sufficient corrosion resistance.
Regarding the strength after brazing, the strength can be increased by adding Mg to the core material, but the erosion of the core material by the brazing material increases, and the brazing property decreases, so that the brazing sheet and the fin The fillets become smaller, which reduces the durability and corrosion resistance of the radiator. In particular, in brazing by Nocolok brazing method, the core material Mg
Exceeds 0.2% by weight, the brazing property is remarkably reduced. Therefore, it is not preferable to add Mg as an alloy composition of the core material.

Therefore, as a technique for improving the strength after brazing without impairing the brazing properties, Japanese Patent Laid-Open No. 2-175 discloses a technique.
093, JP-A-4-198446, JP-A-4-198447, and JP-A-4-198448
(Japanese Patent Application No. Hei 7-90766 is not disclosed because it is not disclosed).

[0004]

However, in the above-mentioned prior art, the corrosion resistance and the durability of the radiator are insufficient for further reducing the thickness of the aluminum alloy composite.

That is, in Japanese Patent Application Laid-Open No. 2-175093, since the Zn content of the skin material is as small as 2% or less, C
If the amount of u exceeds 0.2%, the sacrificial anode effect becomes insufficient, and there is a risk that intergranular corrosion will occur. Further, since the core material does not contain Ti, sufficient corrosion resistance cannot be obtained.

In Japanese Patent Application Laid-Open No. 4-198446, Zn is not added to the skin material, and
Although n, Sn, Ga, and the like are added, these elements are rarely used, so that the production cost is increased and there is a problem in reusability after scrap. Therefore, it is not preferable to add the above-mentioned elements and the like to the skin material.

[0007] In the examples of Japanese Patent Application Laid-Open No. 4-198446, Zn is added, but the addition amount is as small as 1.5%, so that the Cu content of the core material is 0%. If it exceeds 0.2%, the internal corrosion resistance of the alloy composite material is reduced.

In Japanese Patent Application Laid-Open No. 4-198447, 0.5 to 2.0% by weight of Zn is added to the skin material. However, since the amount is small, Cu exceeds 0.2% in the core material. If added, the sacrificial anode effect of the skin material becomes insufficient, and intergranular corrosion may occur.

Further, in Japanese Patent Application Laid-Open No. 4-198448, if Zn is not added to the skin material and Cu is added in excess of 0.2% to the core material, the sacrificial anode effect becomes insufficient. In addition, intergranular corrosion may occur.

The present invention has been made in view of the above problems, and can improve the durability and corrosion resistance of a member brazed by an aluminum alloy composite material, such as a radiator core, and can improve the corrosion resistance. An object of the present invention is to provide a member brazed with an aluminum alloy composite material for brazing having excellent brazing properties.

[0011]

The member brazed by the aluminum alloy composite for brazing according to the present invention is made of Mg.
Is regulated to 0.1% by weight or less, Fe: 0.2% by weight or less, Cu: more than 0.2% by weight and 1.0% by weight or less, S
i: 0.2 to 1.3% by weight, Mn: 0.3 to 1.5
%, Ti: 0.02 to 0.3% by weight, C
the total amount of u and Si is regulated to 0.7 to 1.5% by weight,
Aluminum alloy core material with the balance being Al and unavoidable impurities, Al-Si brazing material formed on one surface of the core material, and Mg: 0.3 to 3 formed on the other surface of the core material
% By weight, Zn: more than 2% by weight and 5% by weight or less, and, if necessary, Si: 0.1 to 1.0% by weight or less, with the balance being an aluminum alloy skin material comprising Al and unavoidable impurities. The core material after brazing is characterized in that the major diameter of the crystal grains in the parallel cross section is 80 μm or more.

In another aluminum alloy composite material for brazing, the core material may further contain Zr: 0.2% by weight or less or Cr: 0.3% by weight or less.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the above-mentioned known technique, since the crystal grains of the core material after brazing are not regulated, when the crystal grains are fine, the thickness of the molten braze on the surface of the brazing material at the time of brazing is reduced. The thickness facilitates the flow of the wax, and there is a danger that the outflow and erosion of the fillet will cause a local decrease in core material thickness. In addition, the erosion of the brazing material into the core material increases, and the size of the fillet formed between the brazing sheet and the fins decreases, so that the durability of the radiator may decrease.

Therefore, it is difficult to produce an alloy composite material having high corrosion resistance and excellent durability and brazing property of the radiator core by the above-mentioned prior art.

However, in the present invention, the composition of the core material and the like is appropriately set, and the crystal grains of the core material after brazing are regulated so that the major axis of the crystal grains in the cross section is 80 μm or more. The durability and corrosion resistance of the brazed member can be improved. Hereinafter, the reasons for limiting the addition of components to the core material, the skin material, and the brazing material of the aluminum alloy composite material for brazing according to the present invention will be described.

FIG. 1 is a sectional view showing the structure of an aluminum alloy composite according to an embodiment of the present invention. This aluminum alloy composite material is obtained by laminating a skin material 2 on one surface of a core material 1 and laminating a brazing material 3 on another surface of the core material 1. The aluminum alloy composite material is formed into a tube 4 as shown in FIG. 2, for example, and a corrugated fin 5 is arranged in the tube 4. As shown in FIG. Are brazed with the aluminum alloy composite brazing material 3 constituting the tube 4. Thereby, the fillet 6 is filled between the aluminum alloy composite material and the fin 4. The brazed member according to the present invention is configured as described above.

Next, the composition of the core material of the above-described aluminum alloy composite will be described.

Mg: 0.1% by weight or less Mg is a component for improving the strength of the core material. However, if added in excess of 0.1% by weight, the brazing property is reduced. Particularly in brazing by Nocolok brazing, the reduction is extremely large. Therefore, the amount of Mg added to the core material is set to 0.1% by weight or less. In order to further suppress the lowering of the brazing property, it is preferable that Mg is not added.

Cu: more than 0.2% by weight and 1.0% by weight or less
Lower Cu is an element that improves the strength of the core material and also improves the corrosion resistance of the brazing material side. However, when Cu is added to the core material, the intergranular corrosion susceptibility is increased, so that the corrosion resistance on the skin surface side is reduced. Therefore, as described later, by adding Zn exceeding 0.2% by weight to the skin material, the potential of the skin material is set to be low with respect to the grain boundary, thereby preventing grain boundary corrosion. In other words, by increasing the amount of Zn added to the skin material, the potential of the skin material with respect to the core material can be set not only to the matrix of the core material but also to the grain boundaries, so that grain boundary corrosion is reduced. Can be prevented.

When the added amount of Cu is 0.2% by weight or less, it is insufficient to improve the strength of the core material. On the other hand, when Cu is added in excess of 1.0% by weight, the melting point of the core material is reduced. Therefore, the brazing operation is reduced. In addition, since the amount of the molten solder that has penetrated into the core material during brazing increases, the size of the fillet between the brazing sheet and the fins decreases, and the durability of the radiator decreases. Therefore, the Cu content is set to exceed 0.2% by weight and 1.0% by weight or less. The upper limit of the Cu content is preferably 0.8% by weight or less.

Si: 0.2 to 1.3% by weight Si is a component for improving the strength of the core material.
M by reaction between Mn-based precipitate and Mg diffused from skin material
Precipitation of the intermetallic compound of g ₂ Si improves the strength of the core material. However, when the amount of Si added is less than 0.2% by weight, it is insufficient to improve the strength of the core material. On the other hand, when the amount of Si exceeds 1.3% by weight, the low melting point phase increases. As a result, brazing workability decreases. In addition, the amount of molten wax that penetrates into the core material during brazing increases, so that the fillet between the brazing sheet and the fins decreases, thereby reducing the durability of the radiator. Therefore, the added amount of Si is set to 0.2 to 1.3% by weight.

The total amount of Cu and Si: 0.7 to 1.5 weight
As the amount% above, when both Cu and Si are added in excess of a predetermined amount, thereby reducing the brazing workability and durability. Further, for the same reason as defining the amounts of Cu and Si, the total amount of Cu and Si is also 0.7 to 1.5% by weight.
It is necessary to

Mn: 0.3 to 1.5% by weight Mn is a component for improving the corrosion resistance, brazing property and strength of the core material. When the addition amount of Mn is less than 0.3% by weight,
Corrosion resistance, brazing property and strength of the core material cannot be sufficiently improved. On the other hand, when the Mn content exceeds 1.5% by weight, a coarse intermetallic compound is generated, so that workability and durability are reduced. Therefore, the added amount of Mn is 0.1.
3 to 1.5% by weight.

Ti: 0.02 to 0.3% by weight Ti is a component that further improves the corrosion resistance of the core material.
If the addition amount of Ti is less than 0.02% by weight, the corrosion resistance of the core material cannot be sufficiently improved.
Even if added in excess of the above, the effect is saturated, and rather, a coarse intermetallic compound is generated, so that workability and durability are reduced. Therefore, the amount of Ti added is 0.02 to 0.5.
3% by weight.

As described above, Ti is an element indispensable for improving the corrosion resistance of the core material. When Ti is added, it precipitates in a layer form in the core material, and suppresses the progress of pitting corrosion in the depth direction. In addition, the potential difference between the skin material and the brazing material is increased in order to shift the core material potential noble. Because you can
It is effective for electrochemically protecting the core material from corrosion.

Cr: 0.3 wt% or less Cr is a component that improves the corrosion resistance, strength and brazing properties of the core material. Even if Cr is added in excess of 0.3% by weight,
It is impossible to further improve the corrosion resistance, strength, and brazing property of the core material, but rather, a coarse intermetallic compound is generated, and thus the workability and durability are reduced. Therefore, C
The amount of addition of r is 0.3% by weight or less. Note that a more preferable Cr addition amount is 0.02 to 0.3% by weight.

Fe: not more than 0.2% by weight Fe refines the crystal grains of the core material. If the added amount of Fe exceeds 0.2% by weight, the amount of molten wax that penetrates into the core material during brazing increases due to the refinement of the crystal grains, so that the fillet formed between the brazing sheet and the fins is increased. And the durability of the radiator is reduced.

Zr: 0.2% by weight or less Zr is a component that coarsens the crystal grains and improves the corrosion resistance and brazing property of the core material, and is added as necessary. Z
Even if r is added in excess of 0.2% by weight, the corrosion resistance and brazing property of the core material cannot be improved any more, and instead, a coarse intermetallic compound is formed, so that workability and durability are increased. Is reduced. Therefore, the amount of added Zr is 0.2
% By weight or less. Note that a more preferable Zr addition amount is 0.02 to 0.2% by weight.

Next, the reason for limiting the major axis of the crystal grains of the core material after brazing will be described.

In the cross section in the thickness direction of the core material after brazing
The major axis of crystal grains: 80 μm or more The aluminum alloy composite for brazing according to the present invention is mainly used as a tube for a radiator. The radiator is brazed together with the tube, header, side supports and fins, and after brazing, the resinous tank is mechanically joined to the header. At this time, the durability of the radiator changes according to the size of the fillet of the tube and the fin. That is,
The larger the fillet, the better the durability.
In order to obtain a larger fillet, it is effective to suppress the intrusion of the molten solder into the core material during brazing. Since the infiltration of the molten solder into the core material occurs through the crystal grain boundary as a pass, it is preferable to make the crystal grains as large as possible.

Therefore, it is necessary that the major axis of the crystal grain in the cross section in the thickness direction of the core material after brazing (that is, the cross section orthogonal to the surface of the core material) be 80 μm or more.

Next, the reasons for limiting the components of the skin material will be described.

Mg: 0.3 to 3% by weight Mg is a component for improving the strength of the skin material. When brazing is heated, Mg added to the skin material diffuses into the core material, thereby generating Mg ₂ Si in the core material and improving the strength of the alloy composite material after brazing. The addition amount of Mg varies depending on the brazing conditions, but if the addition amount is less than 0.3% by weight, the effect of improving the strength is insufficient. It becomes difficult to laminate the core material. Therefore, the added amount of Mg is set to 0.3 to 3% by weight.

Zn: more than 2.0% by weight and 5% by weight or less Usually, when a skin material is used as a sacrificial anode, Mn,
It is effective to add a component having a noble potential, such as Cu, Ti, or Cr, to the core material, but Zn is added to the skin material to further lower the potential of the skin material. In this case, if the addition amount of Cu in the core material is 0.2% by weight or less, a sufficient sacrificial anode effect can be obtained even if the addition amount of Zn in the skin material is 2% by weight or less, and the corrosion resistance is maintained. Can be. However, when the amount of Cu added to the core material exceeds 0.2% by weight, the amount of Zn added to the skin material is preferably more than 2% by weight and 5% by weight or less. This is because if the amount of Zn added to the skin material is 2% by weight or less, the potential of the skin material cannot take a sufficient potential difference with respect to the grain boundaries, causing intergranular corrosion and the corrosion resistance of the skin material side Is to be reduced. On the other hand, when Zn is added to the skin material in excess of 5% by weight,
Furnace contamination may occur during brazing. Therefore, the amount of Zn added to the skin material exceeds 2.0% by weight and 5% by weight.
The following is assumed.

Si: 0.1 to 1.0% by weight or less Since Si is a component for improving the strength of the skin material, it is added as necessary. However, if the amount of Si added exceeds 1.0% by weight, the melting point of the skin material decreases, and there is a risk of burning during brazing. If the Si content is less than 0.1% by weight, there is no addition effect. Therefore,
The addition amount of Si is 0.1 to 1.0% by weight. In addition,
More preferably, it is 0.2 to 0.5% by weight.

In the case where the thickness of the alloy composite material is further reduced, M
By adding n, Cu, Ti, Zr, etc. to the skin material to the same extent as the amount added in the core material, the strength of the skin material can be improved.

Next, the brazing material will be described. As the brazing material, the same Al-Si alloy as a conventionally used brazing material, for example, A4045 or the like can be used. Further, by adding Zn to the brazing material, the brazing material can be positively operated as a sacrificial anode. In this case, the amount of Zn added is preferably the same as the amount of Zn added to the skin material, that is, more than 2% by weight and 5% by weight or less.

[0038]

EXAMPLES Hereinafter, examples of the present invention will be described in comparison with comparative examples outside the scope of the claims of the present invention.

The composition of the core material used in Examples and Comparative Examples is shown in Table 1 below. No. 1 to 8 are core materials satisfying the composition of claim 1 of the present invention;
No. Reference numerals 9 to 17 denote core members that deviate from claim 1 of the present invention.

[0040]

[Table 1]

Table 2 below shows the components of the skin material used in the examples and comparative examples.

No. Nos. 1 to 8 are skin materials satisfying claim 1 of the present invention. Items 9 to 16 deviate from claim 1.

[0043]

[Table 2]

In addition to the core material and skin material shown in Tables 1 and 2, A4045 (10.5% Si, F
e; 0.05% by weight, Cu; 0.05% by weight, Ti;
An aluminum alloy composite for brazing as shown in FIG. 1 was produced using 0.02 wt%, Al; balance) alloy. FIG. 1 shows a cross section of an aluminum alloy composite for brazing according to the present invention. As shown in FIG. 1, in this aluminum alloy composite material, a skin material 2 and a brazing material 3 are laminated on both surfaces of a core material 1. Tables 3 and 4 below show the combinations of the core material and the skin material of each composite material, their thickness, the thickness of the brazing material, and the thickness of the composite material.

[0045]

[Table 3]

[0046]

[Table 4]

The following tests were performed on each composite material having the combinations shown in Tables 3 and 4 above. The test method and test results are shown below.

Brazing test (1) Drop test The flow coefficient was evaluated by a drop test. The results are shown in Tables 5 and 6 below. 5 g of Nocolok flux on the brazing filler metal surface of the aluminum alloy composite for brazing
/ M ² and dried, and then heated at a temperature of 600 ° C. for 5 minutes in a nitrogen atmosphere having a dew point of −40 ° C.

All the examples of the present invention show good brazing properties. In particular, No. 7 in which Zr is added to the core material shows good brazing properties. On the other hand, the amount of Fe in the core material is No. 16 which deviates from claim 1 of the claims, the amount of Mg in the core material is No. 19 which deviates from claim 1 and the total amount of Si and Cu is in the claims. No. 23 exceeding 1 shows a decrease in brazing properties.

(2) Brazing by Combination of Fin and Tube The size of the fillet formed in the fin portion by the combination of the fin and tube and the erosion of the tube were evaluated. The results are shown in Table 7 below.

As shown in FIGS. 2 and 3, a fin and a tube were combined, the same amount of flux was applied as in the drop test, and brazing heat was applied under the same conditions.

In each of the embodiments of the present invention, a good fillet size is obtained and the erosion depth is small. No. 1 having a small crystal grain size. Fillets of 2, 16, and 19 have a small fillet size due to deep erosion. Also, N
Although o23 has a crystal grain diameter within the scope of claim 1 of the present invention, since the total amount of Si and Cu exceeds claim 1, the erosion depth is large and the fin fillet size is small. I have. As described above, the fin fillet size is smaller than that of claim 1 and the durability of the radiator is expected to decrease.

Tensile test The aluminum alloy composite for brazing heated in the same manner as in the above-mentioned brazing test was allowed to stand at room temperature for 7 days, and then a tensile test was performed. The results are shown in Tables 5 and 6.

Each of the examples of the present invention shows a high strength of 170 N / mm ² or more. On the other hand, No. 14 in which the amount of the core material Si deviates from claim 1 of the claims, No. 15 in which the total amount of the core materials Si and Cu deviate from claim 1, and the amount of the core material Cu are in claim 1
No. 17 out of the range, No. 18 in which the core material Mn amount deviates from claim 1, and No. 21 in which the skin material Mg amount deviates from claim 1 are all less than 170 N / mm ² .

Brazing Material Side Corrosion Test The aluminum alloy composite for brazing heated in the same manner as the brazing test described above was subjected to a continuous 250 hour test by the CASS test. The corrosion depth measurement results are shown in Tables 5 and 6 below.
Shown in

The examples of the present invention all show good corrosion resistance on the brazing material side. on the other hand. The No. 16 core material Fe content deviates from claim 1, the No. 19 core material Mg content deviates from claim 1 of the claims, the No. 20 core material Ti content deviates from claim 1, the total amount of the core material Si and Cu is No. 23 out of claim 1 shows a decrease in corrosion resistance.

Skin Material Corrosion Test A brazed aluminum alloy composite heated in the same manner as in the brazing test described above was treated with artificial water (Cl: 300 ppm, S
(O ₄ : 100 ppm, Cu: 5 ppm) was used for the corrosion test. First, 8 parts of the alloy composite were added to 88 ° C artificial water.
It was immersed for an hour, and then left at room temperature for 16 hours while immersed. The corrosion test of the above cycle was performed for 30 days. The results of the corrosion depth measurement are shown in Tables 5 and 6 below.

All the examples of the present invention show good corrosion resistance. On the other hand, No. 19 in which the core material Mg deviates from claim 1 of the claims and No. 20 in which the core material Ti amount deviates from claim 1 show a decrease in corrosion resistance.

[0059]

[Table 5]

[0060]

[Table 6]

[0061]

[Table 7]

[0062]

As described above, according to the present invention,
An aluminum alloy composite for brazing having excellent brazing properties is obtained, and by using this composite for brazing, a member having excellent durability and corrosion resistance can be obtained.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an aluminum alloy composite for brazing according to an embodiment of the present invention.

FIG. 2 is a diagram showing a tube after brazing assembled using the tube made of the composite material.

FIG. 3 is an enlarged view showing a joint between the inner surface of the tube and a fin.

[Explanation of symbols]

 1: Core material 2: Leather material 3: Brazing material 4: Tube 5: Fin 6: Fillet

Claims (4)

[Claims] 1. The method according to claim 1, wherein Mg is regulated to 0.1% by weight or less,
e: 0.2 wt% or less, Cu: more than 0.2 wt%.
0% by weight or less, Si: 0.2 to 1.3% by weight, Mn:
0.3 to 1.5% by weight, Ti: 0.02 to 0.3% by weight, the total amount of Cu and Si is regulated to 0.7 to 1.5% by weight, and the balance is Al and inevitable An aluminum alloy core material made of impurities, an Al-Si brazing material formed on one surface of the core material,
g: 0.3 to 3% by weight, Zn: more than 2% by weight and 5% by weight or less, the balance being an aluminum alloy skin material composed of Al and unavoidable impurities. An aluminum alloy composite material for brazing, wherein the major diameter of the crystal grains having a parallel cross section is 80 μm or more. 2. The skin material further comprises Si: 0.1-1.
The member brazed with the aluminum alloy composite for brazing according to claim 1, containing 0% by weight. 3. The member brazed with the aluminum alloy composite material for brazing according to claim 1, wherein the core material further contains Zr: 0.2% by weight or less. 4. The brazing aluminum alloy composite material according to claim 1, wherein the core material further contains Cr: 0.3% by weight or less. Parts.