JP2002294377A - Aluminum alloy composite material for brazing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an aluminum alloy composite material for brazing which has high strength and high corrosion resistance, and whose thinning is made possible while maintaining its high brazability. SOLUTION: The aluminum alloy composite material for brazing has a core material consisting of an aluminum alloy, an Al-Si based brazing filler metal formed on one side of the core material, and a surface material consisting of an aluminum alloy formed on the other side of the core material, and whose cladding ratio is >=15% of the total thickness. The core material has a composition in which the content of Mg is controlled to, by mass, <=0.2%, and containing <=0.3% Cr, <=0.2% Fe, >0.2 to 1.0% Cu and 0.3 to 1.3% Si, and in which the total of Cu and Si is controlled <=2.0%, and further containing <=1.5% Mn and 0.02 to 0.3% Ti, and the balance Al with inevitable impurities. The surface material has a composition containing 2 to 5% Zn, and further containing at least one or more kinds selected from the groups consisting of 0.3 to 1.2% Mn and 0.04 to 0.9% Si, and the balance Al with inevitable impurities.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention is suitable as a brazing sheet used for a tube of a radiator of an automobile, etc., has high strength and high corrosion resistance, and significantly reduces the thickness while maintaining good brazing properties. The present invention relates to a brazing aluminum alloy composite material that has achieved the above.

[0002]

2. Description of the Related Art In recent years, from the viewpoint of environmental protection and the like, there has been an increasing demand for weight reduction of automobile members, and strength, brazing property,
Significantly thinner (40% or more) while maintaining corrosion resistance
The need has arisen. However, conventional aluminum alloy materials used for radiator tubes and the like in automobiles can achieve a certain degree of thinning, but are insufficient to satisfy the above-mentioned requirements.

[0003] Conventionally, as an aluminum alloy composite material for brazing used for tubes of automobile radiators, etc., Al
-Mn-based 3003 alloy as the core material, Al-Si
A brazing sheet laminated with a brazing material has been used. However, the brazing sheet using the 3003 alloy as a core material had a strength after brazing of about 110 MPa, was low in strength, and was not sufficiently satisfactory in corrosion resistance. The strength after brazing can be improved by adding Mg to the core material made of aluminum alloy, but the erosion of the core material by the brazing material increases, so that the brazing property and corrosion resistance decrease. Resulting in. In particular, brazing by the Nokolock method
When the Mg content in the core material exceeds 0.2% by mass, the brazing property is extremely reduced. For this reason, it is not preferable to add Mg to the core material.

Therefore, as a material whose thickness is reduced without impairing corrosion resistance and brazing properties, Japanese Patent Application Laid-Open No. Hei 8-28 is disclosed.
There is an aluminum alloy composite material disclosed in JP-A-3891 and JP-A-11-61306. JP-A-8-
The aluminum alloy material described in No. 283891 contains 0.3 to 3% by mass of Mg and 2.2 to 5% by mass of Zn in a skin material, and the strength is improved by adding Mg. On the other hand, in the aluminum alloy material described in JP-A-11-61306, instead of adding Mg to the skin material, Mn and Si are added to the skin material to improve the strength.

[0005]

The problem to be solved by the present invention is as follows:
No. 3891 discloses an aluminum alloy material in which strength is improved by adding Mg to a skin material.
When the wall thickness is reduced, Mg reaches the brazing material surface via the core material due to thermal diffusion during brazing, and impairs brazing properties. For this reason, in order to maintain a predetermined brazing property, the thickness of the core material must be increased, and there is a limit to thinning.

On the other hand, the aluminum alloy described in Japanese Patent Application Laid-Open No. 11-61306 attempts to improve the strength by adding Mn and Si to the skin material, but only by adding the Mn and Si components to the skin material. There is a limit to thinning while maintaining corrosion resistance.

The present invention has been made in view of the above problems, and has an aluminum alloy composite for brazing, which has high strength and high corrosion resistance, and enables a significant reduction in thickness while maintaining high brazing properties. The purpose is to provide materials.

[0008]

An aluminum alloy composite material for brazing according to the present invention comprises: a core material made of an aluminum alloy; an Al-Si-based brazing material formed on one surface of the core material; A cladding formed on the other surface of the aluminum alloy and having a cladding ratio of 15% or more of the total thickness, wherein the core regulates Mg to 0.2% by mass or less,
Cr: 0.3% by mass or less, Fe: 0.2% by mass or less, C
u: more than 0.2% by mass and 1.0% by mass or less and Si:
0.3 to 1.3 mass%, and the total amount of Cu and Si is regulated to 2.0 mass% or less, and further, Mn: 1.5 mass% or less and Ti: 0.02 to 0.3 mass. %, The balance being composed of Al and inevitable impurities. The skin material contains Zn: 2 to 5% by mass, Mn: 0.3 to 1.2% by mass, and Si: It is characterized by containing at least one selected from the group consisting of 0.04 to 0.9% by mass and having a balance of Al and unavoidable impurities.

[0009] In the aluminum alloy composite for brazing, further, when the Zn content of the cladding material is 3% by mass or more,
It can be configured so that the Zn / Si ratio is 5 or more.

[0010] The core material may include Zr:
0.2 mass% or less can be contained. Further, the skin material may contain Cu, Ti and Zr as needed,
In this case, Cu is 1.0% by mass or less, Ti is 0.3% by mass or less, and Zr is 0.2% by mass or less.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail. In order to solve the above problems, the present inventors have conducted intensive studies and found that the skin material contains Mn and Si in a predetermined range, and furthermore, the thickness of the skin material is set to a predetermined ratio, so that the brazing property, The inventors have found that the thickness can be significantly reduced while maintaining the corrosion resistance and strength, and have completed the present invention.

In the present invention, the brazing aluminum alloy composite material is obtained by laminating a skin material on one surface of a core material and laminating a brazing material on the other surface.

The reasons for adding components and limiting the composition of the core material, skin material and brazing material of the aluminum alloy composite material for brazing according to the present invention will be described below. First, as a core material, an aluminum alloy to which the following components are added is used.

Mg (magnesium): 0.2% by mass or less Mg is an element that improves the strength of the core material, but when added in excess of 0.2% by mass, the brazing property is reduced. In particular, in the brazing by the Nocolok method, the decrease is extremely large. Therefore, the content of Mg is limited to 0.2% by mass or less. In order to further suppress the decrease in brazing properties, the content of Mg is preferably set to 0.1% by mass or less. Further, at the time of heating for brazing, Mg is diffused from the skin material to the core material, so that the strength of the core material can be improved without impairing the brazing property.

Cu (copper): more than 0.2% by mass and 1.0 quality
% Or less 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 material surface side is reduced. Therefore, by adding Zn in an amount of 2% by mass or more to the skin material, the potential of the skin material can be set to be lower than the grain boundary, and grain boundary corrosion can be prevented. That is, 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 core material matrix but also to the grain boundaries, thereby preventing grain boundary corrosion. be able to. C
If the addition amount of u is 0.2% by mass or less, it is insufficient to improve the strength of the core material, while if Cu exceeds 1.0% by mass, the melting point of the core material is lowered. Therefore, the brazing workability and the high-frequency weldability are reduced. Therefore, the content of Cu is set to be more than 0.2% by mass and 1.0% by mass or less. The upper limit of the Cu content is preferably 0.8% by mass or less.

Si (silicon): 0.3 to 1.3 mass
% Si is an element for improving the strength of the core material, and in particular, Mn-
The strength of the core material is improved by the precipitation of the intermetallic compound of Mg ₂ Si by the reaction between the Si-based precipitate and Mg diffused from the skin material. However, when the addition amount of Si is less than 0.3% by mass, it is insufficient to improve the strength of the core material.
If i is added in excess of 1.3% by mass, the melting point of the core material is lowered, and the workability of brazing and the high-frequency weldability are reduced due to the increase in the low melting point phase. Therefore, the content of Si is set to 0.3 to 1.3% by mass.

The total amount of Cu and Si: 2.0% by mass or less As described above, when both Cu and Si are added in excess of the predetermined amounts, the workability of brazing and the high-frequency weldability are reduced. . In order to prevent this, it is necessary to limit the total amount of addition of Si and Cu to 2.0% by mass or less. Therefore, the total content of Si and Cu is set to 2.0% by mass or less.

Mn (manganese): 1.5% by mass or less Mn is an element that improves the corrosion resistance, brazing property and strength of the core material. If the addition amount of Mn exceeds 1.5% by mass, a compound in which crystals are coarsened is generated, and thus the workability is reduced. Therefore, the content of Mn is set to 1.5% by mass or less.

Ti (titanium): 0.02 to 0.3 mass
% Ti is an element that further improves the corrosion resistance of the core material.
If the added amount of Ti is less than 0.02% by mass, the corrosion resistance of the core material cannot be sufficiently improved. The corrosion resistance of the material cannot be improved, and instead, a compound in which the crystal is coarsened is generated, so that the workability is reduced.
Therefore, the content of Ti is set to 0.02 to 0.3% by mass. As described above, Ti is an indispensable element for improving the corrosion resistance of the core material, and 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. And the addition of Ti makes it possible to shift the core material potential noble. In addition, since Ti has a low diffusion rate in an aluminum alloy and moves little during brazing, the addition of Ti maintains the potential difference between the core material and the brazing material or between the core material and the skin material, and causes It is effective in preventing corrosion of the core material.

Cr (chromium): 0.3% by mass or less Cr is an element that improves the corrosion resistance, strength, and brazing properties of the core material. Even if Cr is added in excess of 0.3% by mass,
Above that, the corrosion resistance, strength and brazing properties of the core material cannot be improved, but rather the workability is lowered due to the coarsening of the crystal of the compound. Therefore, the content of Cr is 0.1.
3% by mass or less. In addition, a more preferable addition amount of Cr is 0.02 to 0.3% by mass.

Fe (iron): 0.2% by mass or less Fe is an element that refines crystal grains in the core material and improves the strength and weldability of the core material. If the added amount of Fe exceeds 0.2% by mass, the corrosion resistance of the core material is reduced. Therefore, the content of Fe is set to 0.2% by mass or less. In addition, a more preferable addition amount of Fe is 0.02 to 0.2% by mass.

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

Mn (manganese): 0.3 to 1.2 mass
% Mn is an element that improves the strength of the skin material. That is, Mn
Is dissolved in the skin material, thereby improving the material strength. M
If the addition amount of n is less than 0.3% by mass, a sufficient Mn solid solution amount cannot be obtained, and the strength cannot be secured. On the other hand, if the added amount of Mn is more than 1.2% by mass, the corrosion resistance is reduced due to an increase in Al-Mn precipitates. Therefore, when Mn is added to the skin material, the Mn content of the skin material is set to 0.3 to 1.2% by mass.

Si (silicon): 0.05 to 0.9 quality
By adding the amount% Si to the skin material as in the case of Mn, the strength is improved. If the addition amount of Si is less than 0.05% by mass, the strength is not sufficiently improved, and if the addition amount of Si is more than 0.9% by mass, the susceptibility to intergranular corrosion increases and the corrosion resistance decreases.
Therefore, when adding Si to the skin material, the range of the Si content is 0.05 to 0.9% by mass. The Mn
And Si may be added at least one of them.

Zn (zinc): 2 to 5% by mass Normally, Zn is added to the skin material to make the potential of the skin material low. In this case, when the addition amount of Cu in the core material is 0.2% by mass or less, a sufficient sacrificial anode effect can be obtained when the addition amount of Zn in the skin material is less than 2% by mass, and corrosion resistance is maintained. be able to. However, as described above, when the addition amount of Cu in the core material is more than 0.2% by mass and 0.8% by mass or less, the addition amount of Zn in the skin material is 2 to 5% by mass. It is necessary to. This is because if the amount of Zn added to the skin material is less than 2% by mass, the potential of the skin material cannot take a sufficient potential difference with respect to the grain boundary, and grain boundary corrosion occurs, and the skin material side On the other hand, if Zn is added in excess of 5% by mass to the skin material, the furnace may be contaminated during brazing. From the viewpoint of obtaining a balance between strength and corrosion resistance in a state where the amount of Si is increased,
The Zn content is preferably at least 3% by mass.

In the case where the thickness of the alloy composite material is further increased, in addition to the above-mentioned additive components in the skin material, C
By adding u, Ti, Zr and the like to the skin material in the same amount as that in the core material, the strength of the skin material can be improved.

Cladding rate of skin material: 15% or more of the total thickness By setting the cladding rate of the skin material comprising the composition of the present invention to 15% or more, the corrosion resistance is maintained even when the thickness is significantly reduced. Good strength is obtained. Cladding rate is 15
%, The strength is reduced, and the ratio of ensuring the corrosion resistance only with the core material is increased, so that the corrosion resistance is reduced. Therefore,
The cladding rate of the skin material having the composition of the present invention is 15
% Or more. In addition, even if the skin material is too thick, the effect such as strength improvement cannot be obtained so much, but the influence of the corrosion of Zn of the skin material becomes large.
% Is preferable.

[0028] Zn is 3% by mass or more, and Zn / Si ratio is 5 or more.
Strength by adding Si in the upper cladding material is improved tends to decrease the corrosion resistance (intergranular corrosion). By setting the Zn / Si ratio to 5 or more, it is possible to achieve both corrosion resistance and strength within a preferable range even when the thickness is significantly reduced. Therefore,
It is preferable that Zn be 3% by mass or more and the Zn / Si ratio be 5 or more.

Next, the brazing material will be described. As the brazing material, an Al-Si based alloy similar to a conventionally used brazing material, for example, an A4045 alloy 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 in the skin material, that is, more than 2% by mass and 5% by mass or less. In addition, since it is necessary to secure a potential difference between the fin material and the outer surface in order to secure the corrosion resistance of the brazing material surface, a small amount of a metal element that increases the potential such as Cu may be added to the brazing material. .

The component amounts of the core material, the skin material and the brazing material may be adjusted before cladding, or may be controlled by controlling heating and cooling conditions such as brazing. is there.

[0031]

EXAMPLES Examples of the present invention will be described below in comparison with comparative examples that fall outside the scope of the claims of the present invention.

First, the component compositions of the core materials used in Examples and Comparative Examples are shown in Table 1 below. Core material shown in Table 1
Nos. 1 to 5 are core materials within the scope of the present invention, and core materials Nos. 6 to 18 are core materials outside the scope of the present invention.

[0033]

[Table 1]

Table 2 below shows the component compositions of the skin materials used in the examples and comparative examples. Skin material shown in Table 2
Nos. 1 to 4 and skin materials Nos. 11 to 13 are skin materials within the scope of the claims of the present invention, and skin materials Nos. 5 to 10 are skin materials outside the scope of the claims of the present invention.

[0035]

[Table 2]

Each core material and skin material shown in Tables 1 and 2 above,
Brazing material (4045 alloy; Si: 10.5% by mass, Fe:
0.05% by mass, Cu: 0.05% by mass, Ti: 0.0
2% by mass and Al: balance) to produce an aluminum alloy composite for brazing as shown in FIG. Figure 1
1 is a cross-sectional view showing an aluminum alloy composite for brazing according to an embodiment of the present invention. As shown in FIG. 1, the alloy composite material 4 is constituted by laminating a core material 1 with both surfaces sandwiched between a skin material 2 and a brazing material 3. Table 3 below shows 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.

[0037]

[Table 3]

The following tests were performed on each composite material having the combinations shown in Table 3 above. Hereinafter, the test method and test results will be described with reference to Table 4 below. The brazing property test is performed by applying 5 g / m ^{2 of} flux for Nocolok to the brazing material surface of the aluminum alloy composite material for brazing and drying, and then starting from room temperature in a nitrogen atmosphere having a dew point of −40 ° C. Immediately after the temperature was raised to the ultimate temperature of 600 ° C., the temperature was lowered, and the temperature was raised and lowered in a total of about 15 minutes.

FIG. 2 is a sectional view showing a part of the tube of the radiator. As shown in FIG. 2, in the actual manufacture of the radiator, the core material 31, the skin material 32 and the brazing material 3
The brazing is performed in a state where the tube 34 made of No. 3, the fin 35 for releasing heat, and the header 36 connecting the tube 34 are combined. The brazing property was evaluated by the flow coefficient by a drop test. The results are shown in the brazing property column of Table 4 below.

As shown in Table 4 below, Example No. 1
No. 7 to No. 7 have excellent brazing properties, but M
The brazing property of Comparative Example No. 19 to which g was added by 0.3% by mass was extremely inferior to those of the Example and other Comparative Examples.

In the tensile test, the aluminum alloy composite for brazing heated in the same manner as in the brazing property test described above was heated at room temperature for 7 minutes.
After standing for days, a tensile test was performed. The evaluation of the tensile strength was evaluated as ○ when the tensile strength exceeded 155 MPa, and evaluated as x when the tensile strength was 155 MPa or less. The results are shown in the column of tensile strength in Table 4 below.

As shown in Table 4 below, Example No. 1
Nos. To 7 all had a high strength exceeding 155 MPa. On the other hand, Comparative Example No. 11
i lower limit, Comparative Example No. 12 is Cu lower limit of core material, Comparative Example N
o.13 is the lower limit of the Mn value of the core material, Comparative Example No.17 is the lower limit of the Si content of the skin material, and Comparative Example No.22 is the lower limit of the Zn content of the skin material, and the strength is lower. It was below 155 MPa.

In the brazing material side corrosion test, the aluminum alloy composite for brazing heated in the same manner as the brazing property test described above was subjected to a continuous 250 hours test by the CASS test. The evaluation of the brazing material side corrosion erosion depth was evaluated as ○ when the erosion depth was 0.07 mm or less, and as × when the erosion depth exceeded 0.07 mm. The results are shown in Table 4 below in the column of brazing material side corrosion erosion depth.

As shown in Table 4 below, Example No. 1
In all of the samples Nos. To 7, the erosion depth was 0.07 mm or less, which was a good result. On the other hand, in Comparative Example No. 14, since Mg was added to the core material in an amount exceeding a predetermined amount, although the strength was improved, the corrosion resistance was reduced. Comparative Example No. 2
4 is the Si content of the core material, Comparative Example No. 25 is the Fe content of the core material, Comparative Example No. 26 is the Cu content of the core material, Comparative Example No. 2
7, the Mn content of the core material, the Ti content of Comparative Example No. 28,
In Comparative Example No. 29, since the Cr content of the core material and Comparative Example No. 30 had the total amount of Si and Cu in the core material exceeding the upper limit of the present invention, although the strength was improved, the corrosion resistance was reduced. have done.

In the skin material side corrosion test, the aluminum alloy composite for brazing heated in the same manner as in the above-mentioned brazeability test was prepared using artificial water (Cl: 300 mass ppm, SO ₄ : 100 mass p
pm and Cu: 5 mass ppm). First, the alloy composite is immersed in artificial water at a temperature of 88 ° C. for 8 hours, then taken out from the artificial water, and left at room temperature for 16 hours while immersed. A corrosion test for 30 days was performed according to such a procedure. The evaluation of the corrosion erosion depth on the skin material side was evaluated as ○ when the erosion depth was 0.03 mm or less, and as × when the erosion depth exceeded 0.03 mm. The results are shown in the column of the corrosion erosion depth on the skin side in Table 4 below.

As shown in Table 4 below, Example No. 1
In all of the samples No. to No. 7, the erosion depth was 0.03 mm or less, which was a good result. On the other hand, in Comparative Example No. 14, the corrosion resistance was low for the same reason as in the above-mentioned brazing material corrosion test. In Comparative Example No. 21, since the amount of Zn added to the skin material was smaller than the predetermined amount, the alloy composite material penetrated. In Comparative Examples Nos. 24 to 30, the corrosion resistance was low for the same reason as in the brazing material corrosion test described above.

[0047]

[Table 4]

[0048]

As described above, according to the present invention,
An aluminum alloy composite material for brazing having high strength and high corrosion resistance and capable of significantly reducing the wall thickness while maintaining high brazing property 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 sectional view showing a part of a tube of a radiator.

[Explanation of symbols]

 1, 31; core material 2, 32; skin material 3, 33; brazing material 4: aluminum alloy composite material for brazing 34; tube 35; fin 36;

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Fumihiro Sato 15 Kinugaoka, Moka-shi, Tochigi Pref. Kobe Steel Moka Works

Claims (2)

[Claims] 1. A core material made of an aluminum alloy, an Al—Si-based brazing material formed on one surface of the core material, and a clad ratio formed on the other surface of the core material is 15% or more of a total thickness. A core material, wherein the core material regulates Mg to 0.2% by mass or less, and Cr: 0.3% or less.
Mass% or less, Fe: 0.2 mass% or less, Cu: more than 0.2 mass% and 1.0 mass% or less, and Si: 0.3 to 1.
3% by mass, and the total amount of Cu and Si is regulated to 2.0% by mass or less. Further, Mn: 1.5% by mass or less and T
i: containing 0.02 to 0.3% by mass, the balance being composed of Al and unavoidable impurities;
n: 2 to 5% by mass, Mn: 0.3 to 1.2% by mass and Si: 0.04 to 0.9% by mass.
An aluminum alloy composite for brazing, characterized in that the balance has a composition consisting of Al and inevitable impurities. 2. The aluminum alloy composite for brazing according to claim 1, wherein the skin material has a Zn content of 3% by mass or more and a Zn / Si ratio of 5 or more.