JPH1088266A - Brazing sheet made of aluminum alloy - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress the reduction of Zn in a brazing filler metal in the case of brazing and heating, to secure excellent corrosion resistance by sacrificial anode effect, to improve the strength of a core material and to thin the product in a brazing sheet made of an aluminum alloy using as Al-Si series brazing filler metal added with Zn for showing sacrificial anode effect by the brazing filler metal. SOLUTION: At least one side of a core material 3 essentially of Al-Mg-Si series is clad with a sacrificial layer 4 contg. 1.0 to 4.0wt.% Zn, and the balance Al with inevitable impurities, furthermore, the surface of the sacrificial layer is clade with an Al alloy brazing filler metal 1 contg. 6.0 to 13.0wt.% Si and 1.5 to 4.0% Zn, and moreover, the difference between the Zn content in the brazing filler metal (AZn) and the Zn content in the sacrificial layer (BZn), i.e., [(AZn)-(BZn)] is regulated to the range of 0 to +1.0wt.%.

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 sheet used for a brazing structure of various heat exchangers and the like, and more particularly, to a heat exchanger and the like by applying an inert gas brazing, for example, a Nocolok brazing. The present invention relates to an aluminum alloy brazing sheet capable of exhibiting excellent corrosion resistance when the brazing structure is assembled.

[0002]

2. Description of the Related Art Conventionally, heat exchangers for automobiles, such as radiators and oil coolers, are generally made of copper or stainless steel-copper, but these use brazing materials containing lead. Recently, an aluminum alloy brazing sheet clad with an aluminum alloy brazing material made of an Al-Si alloy has been frequently used to avoid environmental problems, and a brazing structure such as a heat exchanger has been used. Aluminum alloy brazing sheets are now preferred in terms of weight reduction and the like.

[0003] When assembling a radiator or an oil cooler using an aluminum alloy brazing sheet, corrosion resistance against corrosion from the side in contact with water (generally referred to as internal corrosion) is important. Therefore, in order to improve the internal corrosion resistance, a sacrificial corrosion layer is conventionally provided on the surface in contact with water. This sacrificial corrosion layer adjusts the composition of the alloy so as to have a potential lower than the potential of the core material, and imparts a sacrificial anode effect to the aluminum alloy of the core material. Is effective for lowering the potential, and the addition of Zn rarely deteriorates other characteristics. Therefore, in general, an aluminum alloy whose potential is lowered by adding Zn is used as a sacrificial corrosion layer. Often used.

[0004] Here, when it is not necessary to perform brazing on the water contact side, for example, on the inner surface side of the tube material, an Al-Zn-based alloy or Al-Mg-
A brazing sheet provided with a sacrificial corrosion layer containing Zn such as a Zn-based alloy is used. On the other hand, when it is necessary to perform brazing on the water contact side such as an oil cooler, a normal aluminum alloy brazing material (Al-Si alloy or Al-Si-B) is used as the brazing material on the water contact side.
An alloy obtained by adding Zn to an i-type alloy) is used to give a sacrificial anode effect to a brazing material, that is, a brazing material layer also serves as a sacrificial corrosion layer. In addition, 3003 alloy of a general Al-Mn alloy is used for the core material,
The strength after brazing is about 120 N / mm ² .

[0005]

As described above, when Zn is added to the brazing material to give the sacrificial anode effect to the brazing material layer itself, the corrosion resistance due to the expected sacrificial anode effect depends on the brazing conditions. May not be obtained. Further, thinning is required for further weight reduction, and accordingly, improvement in strength after brazing and heating is required.

Here, regarding the corrosion resistance, the brazing material containing Zn will be melted at the time of heating by brazing. However, since Zn has a high saturated vapor pressure at a high temperature, the amount of Zn from the surface of the molten brazing material is high. Evaporation is likely to occur. That is, since the molten brazing material is in a liquid phase, the diffusion rate of Zn inside the brazing material is high. Therefore, if Zn evaporates from the surface of the molten brazing material and the amount of Zn in the brazing material surface layer decreases, the molten brazing material is Zn easily diffuses and moves from the inside to the surface layer and evaporates from the surface, and as a result, the Zn content of the entire brazing material decreases. Further, in the case where the lower core material of the brazing material is a normal core material containing no Zn, diffusion of Zn in the direction of the core material also occurs in the molten brazing material, which also indicates the amount of Zn in the brazing material. This results in accelerating the decrease. In particular, in the case of the vacuum brazing method widely used for brazing aluminum alloys, since the surface of the molten brazing material is constantly depressurized at the time of brazing heating, evaporation of Zn from the surface of the molten brazing material rapidly progresses. The amount of Zn in the brazing material rapidly decreases, and therefore, the amount of Zn in the brazing material after brazing is reduced, and the effect of making the potential of the brazing material low by Zn is not sufficiently obtained. As a result, the brazing filler metal layer cannot sufficiently exhibit the sacrificial anode effect, and it is difficult to obtain the expected corrosion resistance. Thus, when a Zn-added brazing material expected to have a sacrificial anode effect is used, it is usual to apply brazing in an inert gas atmosphere without applying the vacuum brazing method. That is, since the inert gas brazing is generally brazed in an inert gas atmosphere of about 1 atm, it is considered that the evaporation of Zn during brazing heating is smaller than in the case of vacuum brazing. .

However, even when brazing is performed in an inert gas atmosphere, a considerable amount of Zn actually evaporates under recent operating conditions, so that sufficient corrosion resistance is not always obtained. That was the actual situation. That is, recently, during brazing heating in an inert gas atmosphere, a fan is rotated in a brazing furnace to generate convection in the high-temperature atmosphere gas in order to increase the rate of temperature rise of the material and improve productivity. In many cases, the brazing operation is conducted so that heat is rapidly transferred from the atmosphere to the material, but in such an operation method, the atmosphere gas constantly flows on the surface of the molten brazing material during the brazing heating. Because of the impingement flow, the Zn partial pressure is always maintained from the molten brazing material surface to maintain the equilibrium partial pressure of Zn at the interface of the molten brazing material surface.
Continues to evaporate, and at the same time, Zn from the molten brazing material to the core material side
As a result, although not as much as in the case of the vacuum brazing method, the amount of Zn in the brazing material is reduced, so that the amount of Zn in the brazing material after the brazing is reduced, so that the brazing material becomes In some cases, a sufficient sacrificial anode effect cannot be exerted on the material, and the expected corrosion resistance cannot be obtained.

Here, as one measure for solving the above-mentioned problem, it is conceivable to set a large amount of Zn added to the brazing material in advance, but if the amount of Zn is too large, However, there is a new problem that the brazing properties decrease due to the reaction between Zn and the Nocoloc flux, which is often used in inert gas brazing, so that such a measure cannot be actually applied. Can not.

[0009] Further, in order to reduce the weight of the heat exchanger, it is required to reduce the thickness of the material, and accordingly, it is required to improve the strength of the brazing sheet after heating by brazing. However, the strength of the Al-Mn alloy 3003 alloy or the like generally used as the core material after brazing is about 120 N.
/ Mm ^2, which is not sufficient strength.

The present invention has been made in view of the above circumstances, and an Al--Mg--Si alloy is used as a core material, and Zn is used as a core material.
Aluminum alloy brazing sheet using a brazing material aimed at the sacrificial anode effect by the addition of
Without excessively increasing the amount of n, the decrease in the amount of Zn in the brazing material during brazing is suppressed as much as possible, whereby sufficient corrosion resistance can be exhibited after brazing and heating. It is an object of the present invention to provide a brazing sheet having high strength after brazing and heating and good brazing properties.

[0011]

Means for Solving the Problems In order to solve the above-mentioned problems, in the brazing sheet made of an aluminum alloy of the present invention, basically, an appropriate brazing material added with Zn and a core material are provided. An intermediate layer (sacrifice layer) containing an amount of Zn was provided so that a considerable amount of Zn was secured in the brazing material on the surface even after the brazing.

Specifically, the aluminum alloy brazing sheet according to the first aspect of the present invention has a core material made of an Al-Mg-Si based alloy on at least one surface of which is made of Zn 1.0-4.
A sacrificial layer containing 0 wt% and the remainder consisting of Al and unavoidable impurities is clad.
i 6.0 to 13.0 wt% and Zn 1.5 to 4.0 wt%
% And the balance is clad with a brazing material consisting of Al and unavoidable impurities, and a Zn content (A
Zn) and the amount of Zn (BZn) in the sacrificial layer [(AZn)
− (BZn)] is set in the range of 0 to 1.0 wt%.

[0013] The aluminum alloy brazing sheet according to the second aspect of the present invention provides a brazing sheet made of an Al-Mg-Si alloy, wherein at least one surface of the core material is made of Zn 1.0 to 4.0 wt%.
And Mn 0.1 to 1.5 wt%, Cu 0.0
6-0.3wt%, Ti 0.06-0.3wt%, Mg
0.06 to 0.5 wt%, Si 0.4 to 1.0 wt%,
Cr 0.06 to 0.3 wt%, Zr 0.06 to 0.3 w
t% or more, and the balance is Al
And a sacrificial layer composed of unavoidable impurities is clad, and further contains 6.0 to 13.0 wt% of Si and 1.5 to 4.0 wt% of Zn on the sacrificial layer, with the balance being Al and unavoidable impurities. The brazing material is clad, and the Zn content (AZn) of the brazing material and the Zn content (B
Zn () and [(AZn) − (BZn)] are 0 to 1.0.
It is characterized in that it is determined within the range of wt%.

Further, in the aluminum alloy brazing sheet according to the third aspect of the present invention, at least one surface of a core material made of an Al—Mg—Si alloy has a Zn content of 1.0 to 4.0 wt.
%, And the balance is clad with a sacrifice layer composed of Al and unavoidable impurities.
6.0 to 13.0 wt% and Zn 1.5 to 4.0 wt%
And Bi 0.01-0.3 wt%, BeO.
0001 to 0.002 wt%, In 0.01 to 0.10
wt%, Sn 0.01 to 0.10 wt%, Ga0.01
A brazing material containing at least one of 0.1 wt% to 0.10 wt%, the balance being Al and unavoidable impurities, and a Zn content (AZn) of the brazing material.
[(AZn) − (BZn)
Zn)] is set in the range of 0 to 1.0 wt%.

Further, the aluminum alloy brazing sheet according to the invention of claim 4 is characterized in that at least one surface of a core material made of an Al-Mg-Si alloy has a Zn content of 1.0 to 4.0.
wt%, Mn 0.1-1.5 wt%, Cu
0.06 to 0.3 wt%, Ti 0.06 to 0.3 wt%
%, Mg 0.06 to 0.5 wt%, Si 0.4 to 1.0
wt%, Cr 0.06-0.3 wt%, Zr0.06-
A sacrifice layer containing one or more of 0.3 wt%, the remainder being made of Al and unavoidable impurities is clad, and Si 6.0 to 13.0 is further formed on the sacrifice layer.
wt% and Zn 1.5-4.0 wt%, and B
i 0.01-0.3 wt%, Be 0.0001-0.0
02 wt%, In 0.01-0.10 wt%, Sn0.
01 to 0.10 wt%, Ga 0.01 to 0.10 wt%
Containing one or more of the above, the remainder being clad with a brazing material consisting of Al and unavoidable impurities,
In addition, the difference [(AZn) − (BZn)] between the Zn amount (AZn) of the brazing material and the Zn amount (BZn) of the sacrificial layer is 0 to 0.
It is characterized in that it is determined within the range of 1.0 wt%.

In the aluminum alloy brazing sheet of the present invention, the outermost surface layer, Zn 1.5 to 4.0, is used.
A sacrificial layer made of an aluminum alloy containing 1.0 to 4.0 wt% of Zn is interposed between a brazing material containing 0.1 wt% and a core material containing substantially no Zn. Is determined so as to have a specific relationship as shown in the above equation. This equation indicates that the amount of Zn in the brazing material is greater than the amount of Zn in the sacrificial layer, and that the difference between the two is 1.0 wt% or less.

By interposing such a sacrificial layer containing a specific amount of Zn between the brazing material and the core material, Zn can be transferred from the molten brazing material to the core material during brazing heating. Diffusion is reduced, and the decrease in the amount of Zn in the brazing material during brazing heating is suppressed. As a result, the amount of Zn in the brazing material after brazing heating can be sufficiently ensured. The sacrificial anode effect by the above can be sufficiently exhibited, and excellent corrosion resistance can be secured. That is, when such a sacrificial layer containing Zn does not intervene between the brazing material and the core material and the core material does not substantially contain Zn, it melts during the brazing heating as described above. While Zn evaporates from the brazing material surface and Zn in the molten brazing material diffuses toward the core material, the amount of Zn in the brazing material rapidly decreases, but in the case of the present invention, at least the core material is used. Since the diffusion of Zn in the direction is suppressed, the progress of the decrease of Zn in the brazing material is slowed, so that a considerable amount of Zn can be ensured in the brazing material even after heating by brazing.

Here, the amount of Zn in the brazing material and the amount of Z in the sacrificial layer
The relationship between the n amount and the above expression will be described. First, it is necessary that the amount of Zn in the brazing material is larger than the amount of Zn in the sacrificial layer. This is because the amount of Zn in the sacrificial layer is less than the amount of Zn in the brazing material.
If the amount is larger than the amount, the amount of Zn in the sacrificial layer after the brazing heating becomes larger than the amount of Zn in the brazing material layer, and the potential of the brazing material becomes more noble than the sacrificial layer. This is because the anodic effect cannot be obtained, resulting in a reduction in corrosion resistance. Further, the difference between the Zn content in the brazing material and the Zn content in the sacrificial layer needs to be 1 wt% or less. This is because, when the difference between the two is greater than 1 wt%, the Z direction from the brazing material side to the sacrificial layer side during brazing heating is increased.
n is easily diffused, so that the effect of suppressing the decrease in the amount of Zn in the molten brazing material at the time of heating by brazing cannot be sufficiently obtained, and the amount of Zn in the brazing material after the heating by brazing becomes small. This is because the sacrificial anode effect of the material cannot be sufficiently obtained, and sufficient corrosion resistance cannot be obtained. The difference [(AZn)-(BZn)] between the Zn amount (AZn) in the brazing material and the Zn amount (BZn) in the sacrificial layer is 0 to +1.0 wt.
%, A sufficient effect can be obtained.
It is preferable to be in the range of 0.3 to +0.7 wt%.

Further, by providing a sacrificial layer containing Zn between the brazing material and the core material, a layer having a uniform Zn distribution is formed. In addition, the effect of suppressing the occurrence of sudden pitting can be obtained.

Next, the component composition of each constituent layer in the brazing sheet of the present invention will be described in detail.

<< Component composition of core material >>

First, the core material needs to be an Al-Mg-Si alloy to improve the strength after brazing. Mg: 0.1-0.5%, Si: 0.4-
It is appropriate to use an alloy containing 1.0 wt% and the balance consisting of Al and unavoidable impurities as the core material. The basic components Mg: 0.1-0.5%, Si: 0.4-
Mn 0.06 to 1.2 wt% with 1.0 wt%
%, Cr 0.06 to 0.3 wt%, Zr 0.06 to 0.
It is appropriate to use, as the core material, an alloy containing one or two or more of 3 wt% and the balance being Al and unavoidable impurities. The basic component Mg: 0.1-
0.5%, Si: 0.4 to 1.0 wt%, Cu 0.06 to 0.3 wt%, Ti 0.06 to 0.3 w
An alloy containing one or two of t%, the balance being Al and unavoidable impurities, or a basic component Mg:
0.1-0.5%, Si: 0.4-1.0 wt%, Mn 0.06-1.2 wt%, Cr 0.06-
0.3 wt%, one of Zr 0.06 to 0.3 wt%
Seed or two or more kinds and 0.06-0.3wt% of Cu, Ti
It is appropriate to use, as the core material, an alloy containing one or two of 0.06 to 0.3 wt% and the balance consisting of Al and unavoidable impurities.

The reasons for limiting the desirable component composition of such a core material will be described.

Mg: Mg is an effective element for increasing the strength after brazing, but its effect is small when the amount of Mg is less than 0.10 wt%, and when the amount of Mg exceeds 0.5 wt%, the inert gas atmosphere brazing is performed. Reacts with Nocolok flux, which is widely used in brazing, to significantly reduce brazing properties. Therefore, the amount of Mg is set in the range of 0.10 to 0.5 wt%.

Si: Si is an element effective for improving the strength after brazing in coexistence with Mg. Si content is 0.4
If the amount is less than 1.0% by weight, the effect is small. Therefore, the amount of Si is 0.4-1.0 wt%
Within the range.

Mn, Cr and Zr are effective in improving the strength after brazing, and one or more of these elements are added.

Mn: Mn is an element that increases the strength and improves the pitting corrosion resistance and is effective in improving the resistance to erosion caused by molten solder. Mn content is 0.06wt%
If the amount is less than 1.2% by weight, these effects cannot be obtained sufficiently.
If it exceeds 300, a huge intermetallic compound will be generated, impairing rollability and formability, reducing corrosion resistance, and increasing intergranular corrosion susceptibility. Therefore, the Mn content of the core material is 0.0
It is preferable to be within the range of 6 to 1.2 wt%.

Cr, Zr: Both Cr and Zr are effective elements for increasing the strength after brazing and heating. However, if both are less than 0.06 wt%, the effect cannot be sufficiently obtained. If it exceeds 3% by weight, a huge intermetallic compound is generated, which impairs moldability. Therefore, when Cr and Zr are added, the amount of Cr and the amount of Zr are 0.06 to 0.
It is preferably within the range of 3 wt%.

Cu and Ti are mainly effective for improving the corrosion resistance of the core material, and one or two of them are added. Cu: Cu is an element effective for improving corrosion resistance by increasing the potential of the core material and increasing the strength after brazing. However, when Cu is less than 0.06 wt%, these effects are small. On the other hand, if it is added in excess of 0.3 wt%, pitting corrosion is likely to occur and the corrosion resistance is reduced. Therefore, when adding Cu as needed, the amount of Cu is preferably in the range of 0.06 to 0.3 wt%.

Ti: The addition of Ti is effective to make the potential of the core material noble and to reduce the maximum corrosion depth by changing the pit-like corrosion form into a layer, thereby improving the corrosion resistance. . When the amount of Ti added is 0.0
If the amount is less than 6 wt%, these effects are not sufficiently exerted. On the other hand, if the amount exceeds 0.3 wt%, not only the effects are saturated and the economic efficiency is impaired, but also a large intermetallic compound of Al ₃ Ti is formed. Impairs rollability and formability. Therefore, when Ti is added as required, the amount of Ti is 0.1.
It is preferably in the range of 06 to 0.3 wt%.

In general, aluminum alloys contain Fe as an unavoidable impurity. However, since Fe lowers the corrosion resistance of the core material, it is desirable that these be as small as possible. Specifically, the Fe content is desirably 0.7 wt% or less, and more preferably, the Fe content is 0.3 wt% or less.

By using a core material having the above-described component composition, a brazing sheet having sufficient strength can be obtained even after heating by brazing, and the sheet thickness can be reduced even when a heat exchanger or the like is manufactured using the brazing sheet. Can withstand even thinner than conventional materials,
Therefore, it is possible to satisfy the demand for weight reduction of parts and devices.

<< Component Composition of Sacrificial Layer >>

Next, the sacrificial layer is a layer necessary to maintain the Zn content of the brazing material layer as much as possible after brazing and heating, as described above, and also when the brazing material is used as a brazing structure. After the corrosion progresses and the sacrificial anode effect of the brazing material is no longer exerted, the sacrificial layer exerts a sacrificial anode effect on the core material due to a potential difference from the core material and helps to maintain corrosion resistance.

The main alloying element of such a sacrificial layer is Z
n, containing 1.0 to 4.0 wt% of Zn, with the balance being A
1 and unavoidable impurities, or Zn1.
In addition to 0 to 4.0 wt%, Mn 0.1 to 1.5
wt%, Cu 0.06-0.3 wt%, Ti0.06-
0.3 wt%, Mg 0.06-0.5 wt%, Si0.
4 to 1.0 wt%, Cr 0.06 to 0.3 wt%, Zr
An alloy containing one or more of 0.06 to 0.3 wt% and the balance of Al and unavoidable impurities can be used for the sacrificial layer.

The reasons for limiting the components of such a sacrificial layer will be described below.

Zn: Zn is an element that is added to aluminum to make its potential low and to exert a sacrificial anode effect on a noble core material. 1.0wt% Zn content
If the Zn content is less than 1.0 wt.
If it is less than 1.0%, the difference from the Zn content of the brazing material tends to be 1.0 wt% or more.
%. On the other hand, if Zn is added in excess of 4.0 wt%, the self-corrosion action becomes severe, so the upper limit of the amount of Zn in the sacrificial layer was set to 4.0 wt%. The amount of Zn in the sacrificial layer is not limited to the range of 1.0 to 4.0 wt%, but is naturally restricted by the relationship with the amount of Zn in the brazing material as described above. .

Mn: Mn is an element effective for improving strength and high-temperature strength, and is also effective for erosion due to molten solder. If the Mn content is less than 0.1 wt%, these effects cannot be obtained, and if it exceeds 1.5 wt%, not only these effects are saturated, but also a huge intermetallic compound is generated, impairing the rollability and formability. . Therefore, the amount of Mn when Mn is added is set in the range of 0.1 to 1.5 wt%.

Cu: Cu is an effective element for increasing the strength after brazing, but its effect is small when Cu is less than 0.06% by weight, whereas when Cu exceeds 0.3% by weight, pitting corrosion is caused. Easily occur and the corrosion resistance is reduced. Therefore, the amount of Cu when Cu is added is from 0.06 to 0.
It was within the range of 3 wt%.

Ti: The addition of Ti improves the strength by solid solution and reduces the maximum corrosion depth by changing the pit-like corrosion form into a layer, thereby contributing to the improvement of corrosion resistance. The amount of addition of Ti, the effect is less than 0.06 wt% of is not sufficiently exhibited, whereas if exceeds the 0.3 wt%, not only impair the economy of the effect is saturated, Al ₃ Ti of coarse intermetallic Compounds are generated and impair rollability and formability. Therefore, the amount of Ti when Ti is added is set in the range of 0.06 to 0.3 wt%.

Mg: Mg is an element effective for increasing the strength after brazing, and has the effect of further improving the strength when coexisting with Si. If the Mg content is less than 0.06 wt%, the effect is small, while if it exceeds 0.5 wt%, it reacts with Nocoloc flux widely used in inert gas atmosphere brazing to significantly reduce brazing properties. Therefore, when adding Mg, the amount of Mg is 0.06 to 0.5 wt%.
Within the range.

Si: Si is an element effective for increasing the strength after brazing in coexistence with Mg. Si content is 0.4
If the amount is less than 1.0% by weight, the effect is small. Therefore, the amount of Si when Si is added is set in the range of 0.4 to 1.0 wt%.

Cr, Zr: Both Cr and Zr are effective elements for increasing the strength after brazing and heating, but if both are less than 0.06 wt%, their effects cannot be sufficiently obtained. If it exceeds 3% by weight, a huge intermetallic compound is generated and the formability is impaired. Therefore, when either one or both of Cr and Zr are added, the amount of Cr and the amount of Zr are each set in the range of 0.06 to 0.3 wt%.

It should be noted that Fe is generally contained as an inevitable impurity in an aluminum alloy, but since Fe lowers the corrosion resistance, it is desirable that these be as small as possible. Specifically, the Fe content is desirably 0.7 wt% or less, and more preferably, the Fe content is 0.3 wt% or less.

<< Ingredient composition of brazing material >>

Next, the brazing material is made of an Al-Si alloy generally used as an aluminum alloy brazing material.
A sacrificial anode effect is provided by adding Zn, specifically, 6.0 to 13.0 wt% of Si and 1.5 to 1.5 wt% of Zn.
An alloy containing 4.0 wt%, the balance being Al and unavoidable impurities, or 6.0-13.0 wt% of Si and 1.5-4.0 wt% of Zn, and Bi0.
01-0.3wt%, Be0.0001-0.002w
t%, In 0.01 to 0.10 wt%, Sn 0.01 to
An alloy containing one or more of 0.10 wt% and 0.01 to 0.10 wt% of Ga and the balance of Al and unavoidable impurities is used.

The reasons for limiting the components of the brazing material will be described below.

Si: Si is an essential alloy element as an aluminum alloy brazing material, and lowers the melting point of the brazing material.
It has the effect of improving the flowability of the molten wax. If the Si content is less than 6.0% by weight, the effect is small.
If the content exceeds 3.0% by weight, the workability is reduced.
The Si content was in the range of 6.0 to 13.0 wt%.

Zn: Zn is added to an aluminum alloy to lower its potential and to exert a sacrificial anode effect on a noble core material when added to an aluminum alloy. When the amount of Zn added is 1.5
If the content is less than 4.0 wt%, the effect is small, while if it exceeds 4.0 wt%, the self-corrosion action becomes severe, and the brazing property reacts with the Nocolok flux generally used in inert atmosphere brazing. Will deteriorate.
Therefore, the amount of Zn in the brazing material is set in the range of 1.5 to 4.0 wt%. The amount of Zn in the brazing material is simply 1.5 to 4.
Not only within the range of 0 wt%, but as described above, it is of course regulated by the relative relationship with the amount of Zn contained in the sacrificial layer.

Bi: Bi has the effect of improving the flowability of the molten solder and improving the brazing properties. Bi amount is 0.
If the content is less than 01 wt%, the effect cannot be obtained.
Even if it is added in excess of t%, the effect is saturated and the economy is impaired. Therefore, when adding Bi, 0.01 to 0.3 w
Within the range of t%.

Be: Be also has the effect of improving the flowability of the molten solder and improving the brazing properties. Be amount is 0.
If the content is less than 0001 wt%, the effect cannot be obtained, while the effect is not increased.
Even if it is added in excess of 002%, the effect is saturated and the economy is impaired. Therefore, when Be is added, 0.000
The content was in the range of 1 to 0.002 wt%.

In, Sn, Ga: In, Sn, and Gn all have the effect of improving brazing properties and making the potential lower when added to an aluminum alloy. It contributes to improving the sacrificial anode effect. If the added amount is less than 0.01 wt%, the effect is small, and if it exceeds 0.10 wt%, the potential of the brazing material becomes too low, the corrosion rate is increased, and conversely, the corrosion resistance may be reduced. In any case, the amount of addition is suitably in the range of 0.01 to 0.10 wt%.

In addition to the above-mentioned elements, aluminum alloys contain Fe as an unavoidable impurity. However, since Fe lowers the corrosion resistance of the brazing filler metal, it is preferable that the content thereof is as small as possible. Specifically, the amount of Fe is 0.7 w
It is preferably at most t%, more preferably at most 0.5 wt%.

[0054]

1 to 4 show an example of a lamination structure of a brazing sheet according to the present invention.

FIG. 1 shows an example of the simplest laminated structure in which the characteristic laminated structure of the present invention is applied to only one side of the core material. Zn
Is sacrificed, and the brazing material 1 containing Zn as described above is clad on the surface side of the sacrificial layer 4.

FIG. 2 shows an example of a laminated structure in which the characteristic laminated structure of the present invention is applied to both sides of the core material. In this case, Zn is contained on both sides of the core material as described above. The sacrificial layers 4 and 4 are clad, and the brazing materials 1 and 1 to which Zn is added as described above are clad on the surface side of each of the sacrificial layers 4 and 4, respectively.

3 and 4, the characteristic laminated structure of the present invention is applied to one side of the core material, and only the brazing material or the sacrificial anticorrosion layer is clad on the other side of the core material. An example of a laminated structure is shown below.

That is, in the case of FIG. 3, a sacrificial layer 4 containing Zn as described above is clad on one side of the core material 3, and Zn as described above is added on the sacrificial layer 4. A brazing material 1 is clad, and another brazing material 2 is clad on the other side of the core material 3. The other brazing material 2 in this case is not limited to the brazing material to which Zn is added as described above, but may be a normal Al-Si-based or Al-S
An aluminum alloy brazing material such as i-Bi can be used.

In the case of FIG. 4, a sacrificial layer to which Zn is added is clad on one side of the core material, and the brazing material to which Zn is added is provided on the sacrificial layer 4. 1 is clad, and a sacrificial anticorrosion layer 5 is clad on the other side of the core material 3. In this case, the sacrificial anticorrosion layer 5 may have a potential lower than the potential of the core material 3 and exert a sacrificial anode effect on the core material.
The alloy does not necessarily have to be in the same component composition range as the sacrificial layer 4 made of the Zn-containing alloy described above, which is a feature of the present invention.

The cladding ratio of the brazing material to which Zn is added as described above is not particularly limited, and may be appropriately determined according to the use of the final brazing sheet, the total thickness, and the like. If it is about 20%, good brazing properties can be secured. In addition, the cladding ratio of the sacrificial layer made of the alloy containing Zn is not particularly limited, and may be appropriately determined depending on the use of the final brazing sheet, the overall thickness, the thickness of the brazing material, and the like. If it is about 20%, desired performance can be obtained. When the thickness of the brazing sheet is 0.4 mm or more in consideration of the diffusion of Zn during brazing heating, the effect of the present invention becomes remarkably remarkable.

The method for producing the brazing sheet of the present invention is not particularly limited, as long as a method used for a usual method for producing a clad material is applied.

More specifically, for example, each alloy material is cast, and if necessary, homogenization treatment is performed, and then hot rolling is performed to a predetermined thickness, or hot rolling is not performed. It is only necessary to make a predetermined thickness by face milling only, then perform the clad rolling by hot rolling by superimposing the respective plates, and perform the intermediate annealing as necessary, and then perform the cold rolling to obtain the final thickness, Intermediate annealing may be performed as needed in the middle of cold rolling, or final annealing may be performed as needed after the final cold rolling. Here, a general semi-continuous casting method may be used as the casting method. After the casting, the core material or the sacrificial layer is desirably subjected to soaking in consideration of the erosion resistance of the molten solder.
Although 80 ° C. is appropriate, it is desirable to perform soaking at a high temperature in order to further improve the erosion resistance. In the clad rolling, hot rolling is usually applied as described above. However, when the number of laminations is large, two or more clad rollings may be of course combined. In addition, in order to improve the bondability during clad rolling,
It is desirable that the clad mating surface be cleaned and cleaned beforehand by removing or degreasing the oxide film by pickling or alkali cleaning, solvent degreasing, or the like. The final tempered state may be determined according to the type of heat exchanger component using the brazing sheet, the use of the heat exchanger, etc.
For example, in the case of a core plate for an evaporator, it is necessary to use an O material (completely annealed material) in order to perform press forming.
In addition, for the radiator tube material, a work material of H1n is usually used, and cold rolling, presence / absence of annealing, annealing conditions, and the like may be determined according to each temper state.

The brazing method for brazing using the brazing sheet thus obtained is not particularly limited, but the brazing sheet of the present invention is particularly suitable for flux brazing and inert atmosphere brazing. Suitable for attaching. The use of the brazing sheet of the present invention is not particularly limited, but it is suitable for heat exchanger materials for automobiles, and also suitable for oil coolers for large vehicles such as trucks as well as passenger cars.

[0064]

Embodiments of the present invention will be described below. Alloy codes AA to AO, BA to BR, CA to C in Tables 1 to 3
Each alloy having the component composition shown by P was melted by an ordinary melting method and cast to form an ingot. And alloys AA to A for the core material
With respect to O and the alloys BA to BR for the sacrificial layer, the ingot was subjected to a homogenization treatment according to a conventional method. And alloy B for the sacrificial layer
A to BR and the alloys CA to CP for the brazing material were subjected to hot rolling to a predetermined thickness. Next, the sacrificial layer and the brazing material were clad with the core material by hot rolling to a hot-rolled up cladding thickness of 4 mm. After cold rolling, annealing was performed as necessary, and further cold rolling was performed. , Table 5 sample no. Brazing sheets having a laminated structure and a plate thickness as shown in Nos. 1 to 31 were prepared. In Tables 4 and 5, most of the brazing sheets including the examples of the present invention have a laminated structure as shown in FIG. 3, and only some of the comparative examples (sample Nos. 13 and 14) have the laminated structure shown in FIG. , The laminated structure in which the sacrificial layer 4 was omitted.

For each of the obtained brazing sheets,
After being degreased with a solvent, it is immersed in a commercially available 5% aqueous solution of Nocolok flux, dried, and dried in a nitrogen gas atmosphere.
Brazing heating was performed at a temperature of ° C. for 3 minutes. afterwards,
As a corrosion test, OY water (195 ppm Cl ⁻ , 60 p
pmSO ₄ ²⁺ , 30 ppm Fe ³⁺ , 1 ppm Cu ²⁺ ; p
H3), immersion in 88 ° C. × 8 hr → room temperature × 16 hr
Heating and cooling were repeated in the above cycle, and the corrosion state was observed after 4 months. In addition, the observation of the corrosion state was performed about the part which has not been brazed, ie, the general part (however, the brazing is heated) and the brazed part.
Table 6 shows the results. In Table 6, the amounts of Zn (AZn) in the brazing material (brazing material 1 in FIG. 3) before the brazing and the Z in the sacrificial layer (sacrifice layer 4 in FIG. 3) are shown.
The difference from the n amount (BZn) [(AZn)-(BZn)] is also shown. Here, in the case of the comparative examples having no sacrificial layer (samples No. 13 and No. 14), the above difference in the amount of Zn was indicated by the amount of Zn in the brazing material. Further, as the strength after the brazing heating, after the brazing heating, it was left at room temperature for one week, and then a tensile test was performed to measure the tensile strength.

[0066]

[Table 1]

[0067]

[Table 2]

[0068]

[Table 3]

[0069]

[Table 4]

[0070]

[Table 5]

[0071]

[Table 6]

As is clear from Table 6, in the case of the comparative examples (No. 13 and No. 14) where the Zn-containing sacrificial layer was not interposed between the brazing material to which Zn was added and the core material, It was found that pitting occurred in a general portion other than the brazed portion, the maximum corrosion depth was increased, and penetration occurred, and the corrosion resistance was poor. Similarly, in the comparative example (No. 18) in which the Zn content of the sacrificial layer was too small, pitting occurred in the general portion, and the maximum corrosion depth was large and the penetration was large. On the other hand, in the comparative example (No. 19) in which the amount of Zn in the sacrificial layer was too large, the brazing property was poor and the brazing was poor, so that the corrosion test of the brazed portion was not performed.

No3. In alloys, the amount of Mg in the core material is 0.5
Since it exceeded wt%, it reacted with Nocoloc flux and the brazing property was remarkably reduced, and a brazing defect occurred. Therefore, the corrosion test was not performed. No. In the case of the alloy No. 4, the amount of Si in the core material exceeded 1.0 wt%, so that the core material was melted during the heating by brazing, and the improvement of the corrosion resistance by the sacrificial layer was not obtained. No. In alloy No. 9, the Cu content in the core material was high, causing pitting corrosion, and the corrosion resistance was lower than that of the alloy of the present invention. No. 1
In the case of 5 alloy, the strength is 105 N / m because of the core material 3003 alloy.
m ² is lower than that of the invention alloy.

No. In the alloy No. 16, the Cu content of the sacrificial layer was high, causing pitting and reducing the corrosion resistance. No. In the case of alloy No. 25, the corrosion test was not performed because the sacrificial layer had a high Mg content and reacted with Nocoloc flux to significantly reduce the brazing property. No. In the 26 alloy, since the Si content of the sacrificial layer was high, the sacrificial layer was melted during brazing and the corrosion resistance was reduced.

Further, in the comparative example (No. 29) in which the amount of Si in the brazing material was too small, the brazing property was poor and the corrosion test was not completed. On the other hand, in the comparative example (No. 30) in which the amount of Si in the brazing material was too large, the rollability was poor, so that the edge cracks were severe during rolling, and the sample was not completed. Comparative Example (No. 20) in which the amount of Zn in the brazing material was too small and the amount of Zn in the brazing material was smaller than the amount of Zn in the sacrificial layer.
And a comparative example in which Zn was not added to the brazing filler metal (No. 2).
In 1), pitting occurred in the general part, and the corrosion penetrated. In addition, No. In Nos. 22 and 31, the content itself of each alloy element of the brazing filler metal and the sacrificial layer falls within the range of the individual components specified in the present invention. 31 is a comparative example in which the amount of Zn in the sacrificial layer was larger than the amount of Zn in the brazing material;
o. Comparative Example No. 22 is a comparative example in which the difference between the Zn content of the brazing filler metal and the Zn content of the sacrificial layer exceeded 1.0%. It was much more.

On the other hand, in each of the invention examples in which the component composition of each layer is within the range of the present invention and the difference between the Zn amount of the brazing material and the Zn amount of the sacrificial layer is within an appropriate range, Also showed good corrosion resistance in both the general part and the brazed part.
In addition, the strength after heating by brazing is no. 13, No. 14,
No. In the case where Mg and Si do not coexist in the core material as in No. 15, the strength is clearly as low as 110 N / mm ² , whereas in the case of the alloy whose core material is in the composition range of the present invention, the improvement in strength is apparent at 150 to 200 N / mm ^2. .

[0077]

According to the brazing sheet of the present invention,
Since a sacrificial layer containing an appropriate amount of Zn is interposed between the brazing material to which Zn is added and the core material, the diffusion of Zn from the molten solder toward the core material during brazing heating is suppressed. In addition, a sufficient amount of Zn can be ensured in the brazing material layer even after the heating by brazing, and as a result, the sacrificial anode effect of the brazing material layer can be sufficiently exhibited, and excellent corrosion resistance can be exhibited. In addition, since the amount of Zn in the brazing material is not excessively increased, the brazing property is not reduced even in the case of brazing using Nocoloc flux, so that excellent corrosion resistance and good brazing property can be simultaneously obtained. Can be. Further, by containing appropriate amounts of Mg and Si in the core material, the strength can be improved as compared with the case where the current Al-Mn alloy is used as the core material, and 150 to 200 N after brazing heating.
/ Mm ² , so that when used in a heat exchanger or the like, it is possible to achieve a reduction in the thickness of the plate and a reduction in the overall weight.

[Brief description of the drawings]

FIG. 1 is a first view of a laminated structure of a brazing sheet of the present invention.
It is a schematic longitudinal cross-sectional view which shows the example of.

FIG. 2 shows a second example of the laminated structure of the brazing sheet of the present invention.
It is a schematic longitudinal cross-sectional view which shows the example of.

FIG. 3 is a third view of the laminated structure of the brazing sheet of the present invention.
It is a schematic longitudinal cross-sectional view which shows the example of.

FIG. 4 shows a fourth example of the laminated structure of the brazing sheet of the present invention.
It is a schematic longitudinal cross-sectional view which shows the example of.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Brazing material 2 Brazing material 3 Core material 4 Sacrificial layer 5 Sacrificial anticorrosion layer

Claims (4)

[Claims] 1. A sacrifice layer containing 1.0 to 4.0 wt% of Zn and the balance of Al and unavoidable impurities is clad on at least one surface of a core material made of an Al—Mg—Si alloy, and further sacrificed. On the layer, Si6.0-13.
A brazing material containing 0 wt% and 1.5 to 4.0 wt% of Zn and the balance being Al and unavoidable impurities is clad, and the Zn content of the brazing material (AZn) and the Zn content of the sacrificial layer (BZn) Characterized in that the difference [(AZn)-(BZn)] is set in the range of 0 to 1.0% by weight. 2. A core material made of an Al—Mg—Si alloy containing at least one side of Zn and containing 1.0 to 4.0 wt%, Mn of 0.1 to 1.5 wt%, and Cu of 0.06 to
0.3 wt%, Ti 0.06-0.3 wt%, Mg0.
06-0.5 wt%, Si 0.4-1.0 wt%, Cr
0.06 to 0.3 wt%, Zr 0.06 to 0.3 wt%
, A sacrifice layer containing one or more of the above and the remainder made of Al and unavoidable impurities is clad, and further, on the sacrifice layer, 6.0 to 13.0 wt% of Si and Zn
A brazing material containing 1.5 to 4.0 wt% and the balance being Al and unavoidable impurities is clad, and the Zn content of the brazing material (AZn) and the Zn content of the sacrificial layer (BZn)
[(AZn)-(BZn)] from 0 to 1.0 wt%
A brazing sheet made of an aluminum alloy having excellent corrosion resistance, characterized by being defined in the range of 3. A sacrificial layer containing 1.0 to 4.0 wt% of Zn and the balance of Al and unavoidable impurities is clad on at least one surface of a core material made of an Al—Mg—Si alloy, and further sacrificed. On the layer, Si6.0-13.
0 wt% and 1.5-4.0 wt% Zn and B
i 0.01-0.3 wt%, Be 0.0001-0.0
02 wt%, In 0.01-0.10 wt%, Sn0.
01 to 0.10 wt%, Ga 0.01 to 0.10 wt%
A brazing material containing one or more of the above, and the balance being Al and unavoidable impurities, is clad, and the Zn content (AZn) of the brazing material and the Zn content (B
Zn () and [(AZn) − (BZn)] are 0 to 1.0.
An aluminum alloy brazing sheet excellent in corrosion resistance, characterized in that it is specified in the range of wt%. 4. At least one surface of a core material made of an Al—Mg—Si alloy contains 1.0 to 4.0 wt% of Zn, 0.1 to 1.5 wt% of Mn, and 0.06 to Cu.
0.3 wt%, Ti 0.06-0.3 wt%, Mg0.
06-0.5 wt%, Si 0.4-1.0%, Cr0.
A sacrifice layer containing one or more of the following components, ie, Al and unavoidable impurities, is clad. 0.0-13.0 wt% and Zn1.5
４4.0 wt%, and Bi 0.01-0.3 w
t%, Be 0.0001 to 0.002 wt%, In0.
01 to 0.10 wt%, Sn 0.01 to 0.10 wt%
%, And a brazing material containing one or more of 0.01 to 0.10 wt% of Ga and the balance of Al and unavoidable impurities is clad, and Zn of the brazing material is
The difference between the amount (AZn) and the Zn amount (BZn) of the sacrificial layer [(A
Zn)-(BZn)] is set in the range of 0 to 1.0 wt%. A brazing sheet made of an aluminum alloy having excellent corrosion resistance.