JPH11315337A - Aluminum alloy brazing sheet for formation of brazed tube, and brazed tube - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a brazing sheet capable of reducing thickness and also keeping high strength, excellent in brazability as well as in corrosion resistance of a brazed part even in the case of formation of a brazed tube by forming an Mg-added composition, and also excellent in resistance to intergranular corrosion sensitivity and also to provide a brazed tube using the same. SOLUTION: One side of an aluminum alloy core material 11, having a composition consisting of, by weight, 0.8-1.5% Mn, <=0.2% Cu, 0.1-1.0% Si, 0.01-0.2% Mg, and the balance Al with inevitable impurities, is clad with a sacrificial anode cladding material 12 having a composition consisting of 2.0-10.0% Zn, <=0.10% Mg, and the balance Al with inevitable impurities, and further, the other side of the aluminum alloy core material 11 is clad with a brazing filler metal 13 composed of Al-Si or Al-Si-Zn alloy.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a brazing sheet suitable for use in a heat exchanger for automobiles such as a radiator, a heater core or an oil cooler for forming a pipe by brazing and a brazing formed using the brazing sheet. About pipes.

[0002]

2. Description of the Related Art A tube for refrigerant distribution used in a conventional heat exchanger for automobiles is, for example, a 3003 alloy specified by JIS (Mn: 1.0 to 1.5% by weight%, Cu: 0.05 to 5%). 0.
20%, Si: 0.6% or less, Fe: 0.7% or less, Z
n: 0.1% or less, with the balance being Al) as a core material, an Al-Si brazing material is clad on one surface of the core material, and a 7072 alloy (Cu: 0.1% by weight%) specified by JIS is clad on the other surface. 10
%, Mn: 0.10% or less, Mg: 0.10% or less,
Zn: 0.8 to 1.3%, total of 0.7% or less of Si and Fe, balance Al) The cladding of a sacrificial anode skin material made of, for example, a brazing sheet having a laminated structure inside the sacrificial anode skin material And the butt portion of the brazing sheet is joined by a joining method such as high frequency welding. Such a tube body formed by joining the butted portions of the brazing sheet is generally called an electric resistance welded tube.

[0003] The ERW pipe and the fins and the header plate are combined, and the ERW pipe and the fins are brazed by using the brazing material on the surface of the brazing sheet and the fluoride-based flux applied thereto. And the joint between the ERW tube and the header plate. A heat exchanger in a form assembled by brazing using a brazing sheet using a fluoride-based flux using such a brazing sheet has been widely known in the past, and has become mainstream particularly in the field of heat exchangers for automobiles. .

In the heat exchanger using the ERW pipe as described above, since the refrigerant flows inside the ERW pipe, a flow path through which the refrigerant flows is secured before brazing. It has a structure that can be kept. On the other hand, the clad material is processed by roll forming or the like so that the brazing material surface or the brazing material and the sacrificial anode skin material are bonded together, and then brazed in combination with fins and a header plate. (Japanese Patent Laid-Open No. 9-122)
No. 804).

[0005] Since the conventional electric resistance welded tube is already processed into the shape of the tube before brazing, it cannot be said that the sacrificial anode skin material disposed on the inner surface side of the tube contributes to brazing. Although it was hardly conceivable, in the brazing tube described above, the brazing material and the sacrificial anode skin were joined by brazing to increase the pressure resistance of the tube itself and the joining strength of the tube joint. It had features that could be.

By the way, heat exchangers for automobiles are required to be thinner in order to reduce costs due to environmental problems such as energy saving and weight reduction. At the same time, heat exchangers having sufficiently high strength are required even if they are thin. It has been forced. From this background, ERW pipes are disclosed in Japanese Patent No. 1416.
274, JP-A-2-175093, JP-A-8-30
No. 2439 or Japanese Patent Application Laid-Open No. 9-87788, etc., the Al alloy core material is made of Si, Cu, M
By increasing the strength by adding n or the like and strengthening by adding Mg to the sacrificial anode skin material, it has been possible to achieve high strength even with a thin wall.

[0007]

However, when this type of brazing sheet, which has been used for an electric resistance welded pipe, is directly applied to the above-mentioned brazing tube for a heat exchanger, Mg added to the sacrificial anode skin material is reduced. There has been a problem that the fluoride-based flux reacts at the time of brazing, and the brazing property between the brazing material and the surface of the sacrificial anode skin material is extremely reduced.

This is thought to be due to the phenomenon described below in detail. FIG. 4 shows an example of the structure of this type of brazing tube. The brazing tube A of this example is obtained by bending an Al alloy sheet 5 having a three-layer structure formed by laminating a core material 1, a sacrificial anode skin material 2, and a brazing material 3 at both ends thereof and bending it back to the center. Ends 5 a, 5 a, which are formed so as to have an inverted B-shape in cross section, bent back to the center of alloy sheet 5 and overlapped
The part a is brazed. FIG. 5 shows an enlarged structure of a brazing portion of the brazing tube A shown in FIG. At the center of the alloy sheet 5, the ends 5 a and 5 a of the alloy sheet 5 are butted and brazed on the sacrificial anode skin material 2 in a superposed state. That is, the brazing materials 3, 3 of the end portions 5a, 5a of the alloy sheet 5 are attached and brazed at this portion, and the front end portions of the end portions 5a, 5a are sacrificed at the central portion side of the alloy sheet 5. It is brazed at the portion where it comes into contact with anode skin material 2. In this state, two passages 6 and 7 are formed inside the brazing tube A to constitute the tube A.

In the brazing tube A having a brazing structure as shown in FIG. 5, a sacrificial anode skin material 2 exists in addition to the core material 1 and the brazing material 3 around the brazing portion. At this time, the constituent elements of the core material 1, the sacrificial anode skin material 2, and the brazing material 3 may be mutually diffused into the brazing portion by high-temperature heating. However, as described above, this type of brazing sheet has a sacrificial anode skin material 2 for reducing the thickness and improving the strength.
When Mg is diffused in the brazing portion, flux is usually applied to the brazing portion at the time of brazing (a eutectic component of KAlF ₄ and K ₃ AlF ₆ ).
It is considered that F (fluorine) contained in potassium fluoraluminate (KAlF ₄ ) contained in the above reacts with Mg to generate MgF ₂ , which significantly lowers the brazing strength.

Further, according to the study of the present inventors, it is considered that the brazing property of the brazing tube largely depends on the shape after molding. That is, it is considered that the Mg content of the core material or the sacrificial anode skin material greatly affects the mechanical properties and moldability before molding, and it is necessary to select an appropriate Mg content in the core material or the sacrificial anode skin material. I get it. Further, merely reducing the Mg content to improve the brazing properties not only does not provide the effect of improving the strength of the brazing sheet but also increases the Mg content.
It is considered that the content also has an effect on pitting corrosion resistance.
When the g content is reduced, there is also a problem that the erosion of the core material by the wax becomes remarkably large. Furthermore, although the Mg content in the sacrificial anode skin material has an effect on pitting corrosion resistance, the present inventor's research clearly shows that the Zn content of the brazing sheet can make the corrosion mode entirely soluble. Therefore, it is considered that there is a possibility that the corrosion resistance of the brazing sheet can be controlled by controlling the Mg content and the Zn content. Furthermore, it is thought that the additional elements such as Si also have an effect on the corrosion resistance and strength of the brazing portion of the brazing sheet. It has been demanded that it has excellent workability, excellent brazing strength and corrosion resistance, and good corrosion resistance.

The present invention has been made in view of the above-mentioned circumstances, and it is possible to reduce the thickness and maintain a high strength, and even when a brazing tube is used, the brazing portion has excellent corrosion resistance and has excellent brazing properties. Another object of the present invention is to provide an excellent brazing sheet and a brazing tube using the same.

[0012]

According to the present invention, in order to solve the above problems, Mn: 0.8% to 1.5% by weight%,
u: 0.2% or less, Si: 0.1 to 1.0%, Mg: 0.0
1 to 0.2%, and Zn: 2.0 to 10.0 on one surface of an aluminum alloy core material containing the balance of Al and inevitable impurities.
%, Mg ≦ 0.10%, a sacrificial anode skin material comprising the balance of Al and unavoidable impurities is clad, and the other surface of the aluminum alloy core is made of Al-Si or Al-Si- It is characterized in that a brazing material made of a Zn-based alloy is clad. Specific amount of M to sacrificial anode skin material
By adding g, even in a structure in which the sacrificial anode skin is disposed in the brazing portion, the reaction between Mg and the flux in the sacrificial anode skin is minimized, resulting in a reduction in brazing strength. The decrease phenomenon is suppressed. Also, by defining the amount of Mg contained in the core material, a brazing sheet having better brazing properties can be obtained. Furthermore, by restricting the amount of Cu contained in the core material to a specific range, the corrosion rate of the brazing sheet itself can be suppressed, and the corrosion rate of the brazed portion can also be suppressed.

According to the present invention, Mn: 0.8% to 1.5% by weight.
%, Cu: 0.2% or less, Si: 0.1 to 1.0%, M
g: 0.01-0.2%, and Zr: 0.05-0.2%
0.2%, Ti: 0.05-0.2%, Fe: 0.05-0.2
One or two or more of the 0.5%, one side of the aluminum alloy core material containing the remaining Al and unavoidable impurities,
Zn: 2.0 to 10.0%, Mg ≦ 0.1%, a sacrificial anode skin material comprising the balance of Al and unavoidable impurities is clad, and A is coated on the other surface of the aluminum alloy core material.
It is characterized in that a brazing material made of an l-Si-based or Al-Si-Zn-based alloy is clad. By specifying the amount of Zr, the amount of Ti, and the amount of Fe in addition to the above-described specification of the Mg content and the Cu content, the effect of improving the strength of the brazed portion and adjusting the corrosion rate can be achieved.

Further, in the present invention, by further adding In and Sn to the sacrificial anode skin material, a brazing sheet having more excellent pore corrosion resistance can be obtained.

Further, the present invention provides a brazing sheet according to any one of the above, which is formed into a tubular shape by molding and brazing, wherein a sacrificial anode skin material is located at the brazing portion and the sacrificial anode skin material is brazed. Is characterized in that it constitutes a part of.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. FIGS. 1 and 2 show an embodiment of a brazing sheet according to the present invention. A brazing sheet 10 of this embodiment has a sacrificial anode skin on one side (upper surface in the embodiment shown in FIG. 1) of a sheet-like core material 11. Lumber 12
The brazing material 13 is clad-bonded to the other surface of the core material 11 (the lower surface in the embodiment shown in FIG. 1). In the brazing sheet 10 described above, the core material 11, the sacrificial anode skin material 12, and the brazing material 13 are each formed of an aluminum alloy described later.

The aluminum alloys constituting the core material 11, the sacrificial anode skin material 12, and the brazing material 13 in the present invention and the reasons for limiting the components in each aluminum alloy will be described below. "Core material" The core material 11 is Mn: 0.8% to 1.0% by weight.
5%, Cu: 0.2% or less, Si: 0.10 to 1.0%,
It is preferable to be composed of an aluminum alloy containing Mg: 0.01 to 0.1% and the balance being Al and unavoidable impurities. And furthermore, in addition to these compositions, Z
r: 0.05 to 0.2%, Ti: 0.05 to 0.2%, F
e: It is preferable that one or two or more of 0.05 to 0.5% are contained. In the present invention, when the upper limit value and the lower limit value of the composition range are indicated by connecting them with “〜”, the upper limit value and the lower limit value are included in the range unless otherwise specified. Means a range of 0.8% or more and 1.5% or less.

Mn: Mn crystallizes or precipitates as an intermetallic compound and is effective for improving the core material strength after brazing. Further, the potential of the core material is made electrochemically noble to improve the pitting corrosion resistance not only on the sacrificial anode skin material side but also on the brazing material side. The Mn content is preferably in the range of 0.8 to 1.5%,
When the content exceeds this range, the workability such as rolling is reduced, and the effect of further improving the strength becomes difficult to be obtained.On the other hand, when the content is below this range, the effect of improving the strength after brazing is reduced. It is insufficient, and the effect of improving pitting corrosion resistance is also insufficient.

Cu: Cu partially dissolves in the Al base to improve the strength after brazing, and makes the potential of the core material electrochemically noble so that the resistance of the brazing material side as well as the sacrificial material side is improved. It also has the effect of improving pitting. For this reason, the Cu content is preferably in the range of 0.2% or less. If the Cu content exceeds this range, the corrosion rate becomes too fast, and in particular, the corrosion rate of the brazed portion becomes too fast. There's a problem. That is, the corrosion rate of the brazing sheet itself can be suppressed, and at the same time, the corrosion rate of the fillet formed by melting the brazing material in the brazing portion and spreading to the brazing portion can be suppressed. As described above, by suppressing the corrosion rate of the fillet portion of the brazing portion in addition to the brazing sheet 10, the life of the brazing tube including the brazing portion can be extended. Cu here
The content has a relationship with the Zn content in the sacrificial anode skin material 12 described later. If Zn is increased in the sacrificial anode skin material 12 to 2 to 10% as described later, the regulation of the Cu amount becomes important. That is, when an electrochemical potential gradient is formed from the sacrificial anode skin material 12 side to the core material 11 side, if the sacrificial anode skin material 12 contains a large amount of Zn, the sacrificial anode skin material 12 becomes more base and the potential gradient becomes large. Become. In order to sufficiently exhibit the sacrificial anode skin material 12, the Zn needs to be contained in the sacrificial anode skin material 12 in a large amount.
Contains Zn at a high concentration, and a large amount of Cu
When contained, the corrosion rate becomes too fast, so that the whole is quickly corroded even if it is excellent in terms of pitting corrosion resistance. From this viewpoint, it is important to define the Cu content in the above-mentioned range.

If the core material 11 does not contain Cu, the strength of the brazing sheet 10 may be too low. Further, Cu can make the potential difference between the surface of the sacrificial anode skin material 13 and the surface of the brazing material 12 and the inside of the core material 11 large enough to make the potential of the core material 11 noble. . That is, the sacrificial anode skin material 1
By ensuring a sufficient potential difference between 2 and the core material 11,
Corrosion mainly occurs in the sacrificial anode skin 12 and the core 11
Corrosion can be suppressed. In consideration of the above conditions and the above-mentioned corrosion rate, the Cu content is preferably 2 atomic% or less, and more preferably 0.01% or more even in the range of 2 atomic% or less.

Si: Si is dispersed as an Al-Mn-Si compound and solid-dissolves in an Al matrix to improve the strength.
The range of 0.10% to 1.0% is preferable, but if the content exceeds this range, the melting point is lowered and there is a risk of melting during brazing.

Zr, Ti: Zr and Ti are dispersed as fine intermetallic compounds or solid-dissolved in a matrix after brazing to improve the strength.
A range of 2% is preferable, but if the content exceeds this range, the workability is reduced, and if the content is below this range, the strength improving effect tends to be insufficient. Mg: diffused toward the sacrificial anode skin by heat treatment at the time of brazing, etc., to uniformly and uniformly generate a starting point of corrosion, improve pitting corrosion resistance, and further enhance the overall corrosion promotion effect of Zn in the sacrificial anode skin. Since it has the effect of enhancing
The range of 0.2% is suitable, but if the content exceeds this range, the brazing property is impaired, the strength before molding becomes too high, the moldability is reduced, and the content is within the above range. If it is lower than the above, the effect of improving the strength is reduced. Fe: Fe crystallizes or precipitates as an intermetallic compound and improves the strength after brazing. Therefore, the range of 0.05 to 0.5% is preferable, but if the content exceeds this range, corrosion occurs. The speed may be too high.

"Sacrificial anode skin material"
It is preferable that the composition contains 2.0 to 10.0% of n and 0.01 to 0.1% of Mg and the balance is composed of Al and inevitable impurities. In addition to these compositions, In:
0.01 to 0.2%, Sn: 0.05 to 0.2%, 1
It is preferable to include one or more species.

Zn: Zn makes the potential of the sacrificial anode skin material 12 low, forms a potential distribution effective for anticorrosion from the surface of the sacrificial anode skin material to the core material 11, improves pitting corrosion resistance, and reduces the form of corrosion. Since it is important to change from a pitting type to a general corrosion type, it is preferable to contain the Al in the range of 2.0 to 10.0%. However, if the Zn content exceeds this range, the workability is reduced. And the self-corrosion rate becomes too fast,
Conversely, if the Zn content falls below the above range, the effect of improving pitting corrosion resistance tends to be insufficient. Mg: Mg is preferably contained in a range of 0.01% to 0.1% because Mg causes a fine and uniform starting point of corrosion, improves the pitting corrosion resistance, and further enhances the effect of promoting the overall corrosion of Zn. If the amount exceeds this range, the brazing property is inhibited, and the hardness before molding may be excessively high and the moldability may be reduced, and the effect is insufficient if the content is less than the above range. Become.

In, Sn: Since these elements lower the potential of the sacrificial anode skin material 12 and improve the sacrificial anode effect,
It is preferable that one or more of In: 0.01 to 0.2% and Sn: 0.05 to 0.2% are contained.
However, if it seems to contain these elements more than the above-mentioned range, the cost increases, and even if the content exceeds the above-mentioned range, the effect is small, and the content may be below the above-mentioned range. . In addition to the above-mentioned elements,
One or two of Si, Be, and Mn are used as the sacrificial anode skin material 12.
The species or more are 0.01 to 1.0% in Si, 0.0002 to 0.1% in Be, and 0.01 to 1.0% in Mn.
It may be contained in the range of 0.5%.

"Brazing material" In this embodiment, the brazing material 13 is made of Al.
It goes without saying that brazing materials used for forming ordinary brazing tubes, such as -Si-based and Al-Si-Zn-based ones, can be used as appropriate. In the case of an Al-Si system, typical ones are Si 10%, the remainder is Al, Al-Si-
In the case of a Zn-based material, a typical material is Si 7.5%, Z
n2%, with the balance being Al.

Next, FIG. 2 shows a cross section of a brazing tube for a heat exchanger constituted by using a brazing sheet 10 formed by cladding and pressing a core material 1, a sacrificial anode skin material 12, and a brazing material 13 having these compositions. 1 shows an embodiment of a structure. The brazing tube B of this embodiment is formed by rounding and bending both ends of the brazing sheet 10 in the same direction so that the sacrificial anode skin material 12 is on the inner surface side, and bending the end portions 10a and 10a of the brazing sheet 10 on the distal end side. The brazing sheet 10 is formed in a B-shape with an inverted cross section, with the back-to-back parts abutting against the central portion of the brazing sheet 10. That is, the end 10 of the brazing sheet 10 is located at the center of the brazing sheet 10.
a, 10a are attached back to back, and the tip 10b of each end 10a is bent at an angle of approximately 90 ° to the end 10a in opposite directions to each other, so that the sacrificial surface on the inner side of the brazing sheet 10 is formed. It is attached to the anode skin material 12. In the above structure, the inside of the brazing tube B is partitioned into two flow paths 16 and 17 by the ends 10 a and 10 a of the brazing sheet 10. And both are brazed by the brazing material 13 which exists in the contact part of the end parts 10a and 10a attached back to back,
The tip portions 10b and 10b of the brazing sheet 10 which are in contact with the sacrificial anode skin 12 on the inner surface side are brazed by the brazing material 13 to the sacrificial anode skin material 12 on the inner surface side of the brazing sheet 10.
Has been brazed to.

In the brazing tube B having such a structure, the brazing sheet 10 is brazed at the end portions 10b and 10b of the brazing sheet 10 and the inner surface of the brazing sheet 10 where the sacrificial anode skin 12 is abutted. In addition, there is a high possibility that the additional components contained in the core material 11 and the sacrificial anode skin material 12 are diffused into the brazed portion by heat during brazing. Here, the core material 11 of the brazing sheet 10 used in the present invention
Since the Mg content of the sacrificial anode skin material 12 is kept low within a specified range, even if Mg diffuses into the brazing portion, there is little adverse effect on the brazing properties due to Mg diffusion.

FIG. 2 shows the reason for this in detail.
To manufacture brazing tube B, brazing sheet 10
Before bending as shown in FIG.
Flux (typically aluminum fluoride)
Mukari salt "mainly KAlF _Four"
In many cases, F also contains F. )
Fold the brazing sheet 10 with flux applied
And then carried into a heating furnace for brazing and heated.
Heating to a predetermined temperature in a furnace to melt the brazing material 13
And brazing. Therefore, the brazing
And F are present, but this Mg and F
MgF_TwoEasily to generate brazing properties
Amount of Mg contained in the sacrificial anode skin material 12
Should be within the range of 0.01 to 0.2% as described above.
It is important. The Mg content of the core material 11 was also 0.1%.
It is preferable to set the following range.

Next, in order to manufacture the brazing sheet 10, an Al alloy plate material for forming the core material 11, an Al alloy plate material for forming the sacrificial anode skin material 12, and a brazing material 13 are formed.
Each of the Al alloy sheets for forming is formed by casting from a molten alloy having a required composition, and if necessary, these are surface-cut and then integrated into a three-layer structure by clad pressure bonding, and subjected to a required number of rolling processes. The brazing sheet 10 is adjusted to a desired thickness, subjected to final rolling, and then subjected to plastic working.
Can be obtained.

The rolling ratio at the time of the final rolling performed here is preferably in the range of 15 to 35%. By performing the final rolling in this range, the formability can be improved, and if the rolling ratio exceeds this range, it becomes difficult to form, and it becomes difficult to form a brazed tube by brazing heat treatment. In other words, if the final rolling ratio is high, the rigidity of the final rolled material is increased and springback is likely to occur during plastic working, so that the force to return to the sheet shape when the sheet-like final rolled material is formed into a brazed tube. Becomes too strong to make satisfactory brazing. On the other hand, if the final rolling ratio is lower than the above-mentioned range, the brazing material is likely to erode the brazing material during brazing, so that the brazing property is significantly reduced.

By using the brazing sheet 10 manufactured as described above to manufacture the brazing tube shown in FIG. 2, the overall strength is high, the brazing portion has excellent corrosion resistance and brazing strength, and good workability. A brazing tube B can be obtained.

FIG. 3 shows a second embodiment of a brazing tube for a heat exchanger constituted by using the brazing sheet 10 of the present invention shown in FIG. 1. The brazing tube C of this embodiment is similar to that of FIG.
The brazing tube B shown in FIG.
The end portions 10a and 10a of the brazing sheet 10 are directly brought into contact with the sacrificial anode skin material 12 at the central portion of the brazing sheet, and the abutting portion is a brazed portion 15C, and the cross section is inverted B
It is a letter-shaped configuration. Also in this structure, the tip of the end 10a of the brazing sheet 10 is brought into contact with the sacrificial anode skin 12 of the brazing sheet 10 to braze this portion. Since the skin material 12 and the brazing material 13 are present,
At the time of brazing, the constituent elements of the core material 11, the sacrificial anode skin material 12, and the brazing material 13 interdiffuse, resulting in a state equivalent to that of the brazing tube B of the first embodiment described above. The effect of can be obtained.

[0034]

EXAMPLE An alloy for a core material, an alloy for a sacrificial anode skin material, and an alloy for a brazing material having the component compositions shown in the following Tables 1 and 2 were each melted and cast to produce ingots, and these ingots were manufactured. After the facing, after homogenization treatment under ordinary conditions, hot rolling and cold rolling were performed, and the alloy for the core material was processed to a thickness of 160 mm, the alloy for the sacrificial anode skin material, and the alloy for the brazing material to a thickness of 20 mm.
These three members are clad and rolled while hot, and then subjected to cold rolling while being appropriately subjected to intermediate annealing so as to have various final cold rolling rates, thereby producing a 0.3 mm thick clad material. did. Further, the rolling ratio at the time of the final rolling of the cold rolling was set to 35%.

[0035]

[Table 1]

[0036]

[Table 2]

Further, a fluoride-based flux was applied to the obtained brazing tube, and as a brazing heat treatment, heat treatment was performed at 600 ° C. for 3 minutes in a high-purity nitrogen gas atmosphere to evaluate brazing properties. Evaluation of brazeability: Observation of cross section after brazing, fillet formation state (shape and size)
Was evaluated from. 〇 indicates the best one, △ indicates the one with good brazing properties, and X indicates one with poor brazing properties.

Subsequently, for the purpose of evaluating corrosion resistance, the brazing sheet was subjected to a brazing heat treatment in the form of a sheet and subjected to a corrosion test in which it was immersed in tap water at 40 ° C. to which 10 ppm of Cu ²⁺ ions had been added for 20 days. The pit depth was measured. Furthermore, in order to evaluate the corrosion resistance of the brazed part,
After the brazing tube was formed by brazing, 10 ppm of Cu ²⁺ ions were added to the inside of the brazing tube.
A corrosion test was performed for 10 days while constantly circulating tap water at ℃. After 10 days, the cross section was observed and evaluated based on the degree of corrosion of the brazed portion. Further, for the purpose of evaluating the strength after brazing, the brazing sheet was brazed in a high-purity nitrogen gas atmosphere under the assumption of brazing.
A heat treatment was performed at 3 ° C. for 3 minutes. Table 3 summarizes the above results.

[0039]

[Table 3]

As is evident from the results shown in Table 3, all of the samples provided with the sacrificial anode skin material having a composition other than the present invention have any of the brazing properties, the maximum pit depth and the tensile strength. It turned out that it was inferior to the sample of the present invention. In Table 3, in the brazing sheet 5 using the core material A to which Mg is added below the specified range, the maximum pitting depth is large and the pitting becomes large.
The brazing sheet 6 using the core material E and G having the Si content below the specified range is inferior in the brazing property evaluation, and the brazing sheet 7 using the core material E and G having the Si amount less than the specified range uses the core material F containing an excessive amount of Si. The brazing sheet 8 having the core material melted at the time of brazing, and the brazing sheet using the core material H containing excessive Cu has inferior corrosion resistance at the brazing portion, and has
The brazing sheet 11 using the core materials I and J in which the n amount was out of the specified range was inferior in tensile strength or cracked during rolling. Further, sacrificial anode skin materials c and f in which Mg is out of the specified range
The brazing sheets 14 and 15 using slag have poor brazing property evaluation and sacrificial anode skin materials g and h with Zn outside the specified range.
The brazing sheets 16 and 17 using the sacrifice anode skin material i in which the maximum pitting depth is large and the amounts of In and Sn added are excessive are slightly lower in the tensile strength. There is a problem of high cost,
The core material of the brazing sheet 19 using the sacrificial anode skin material j containing excessive amounts of Si, Be and Mn was melted during brazing.

[0041]

As described above, the brazing sheet of the present invention has a specific amount of Mn, Cu, Si, Mg by weight%.
Anode material containing a specific amount of Zn and Mg on one side of the core material containing, and brazing material clad on the other side, particularly with the Cu content of the core material in a specified range, Since the amount of Mg is suppressed to a low level, even when a flux containing a fluoride is provided in the brazing portion, the strength of the brazing portion does not deteriorate much, and the pitting corrosion resistance of the brazing portion does not deteriorate. There is an effect that a brazing sheet that can be attached can be provided. In addition, since Cu makes the potential noble, the larger the amount of the core material Cu, the more the potential difference from the sacrificial anode skin material can be obtained, and the corrosion rate of the brazing sheet itself can be suppressed. If it is low, the corrosion rate becomes low and the corrosion rate can be suppressed.

Further, by adding specific amounts of In and Sn to the above composition, the sacrificial anode effect can be further improved by making the sacrificial anode skin material have a low corrosion potential.

Next, a brazing tube is formed by using the above-mentioned brazing sheet, and even if the brazing tube has a brazing portion of a brazing sheet on which a sacrificial anode skin material is disposed, a sacrificial anode skin is formed. Since the amount of Mg contained in the material is suppressed to a specific low content and contains Cu in a specified range, a brazed tube having high brazing portion strength and excellent pitting corrosion resistance can be obtained. . Therefore, the brazing tube of the present invention has a feature suitable for a heat exchanger.

[Brief description of the drawings]

FIG. 1 is a sectional view of a brazing sheet according to a first embodiment of the present invention.

FIG. 2 is a sectional view showing a brazing tube formed of the brazing sheet shown in FIG. 1;

FIG. 3 is a cross-sectional view showing a second embodiment of a brazing tube configured using the brazing sheet according to the present invention.

FIG. 4 is a cross-sectional view showing an example of a brazing tube configured using a conventional brazing sheet.

FIG. 5 is an enlarged sectional view showing a brazing portion of the brazing tube shown in FIG. 4;

[Explanation of symbols]

B, C: brazing tube, 11: core material, 12: sacrificial anode skin material, 13: brazing material, 15A, 15B, 15C: brazing portion.

Continued on the front page (51) Int.Cl. ⁶ Identification code FI B23K 35/28 310 B23K 35/28 310B F28F 1/02 F28F 1/02 B 19/06 19/06 B 21/08 21/08 B

Claims (4)

[Claims] 1. Mn: 0.8% to 1.5% by weight, C
u: 0.2% or less, Si: 0.1 to 1.0%, Mg: 0.0
One side of an aluminum alloy core material containing 1 to 0.2%, the balance being Al and unavoidable impurities, Zn: 2.0 to 10.0%, Mg ≦ 0.10%,
A sacrificial anode skin material comprising the remaining Al and unavoidable impurities is clad, and the other surface of the aluminum alloy core material is Al-S
An aluminum alloy brazing sheet for forming a brazing tube having excellent brazing properties and corrosion resistance, wherein a brazing material made of an i-based or Al-Si-Zn-based alloy is clad. 2. Mn: 0.8% to 1.5% by weight, C
u: 0.2% or less, Si: 0.1 to 1.0%, Mg: 0.0
1 to 0.2%, Zr: 0.05 to 0.2%,
One or two or more of Ti: 0.05 to 0.2% and Fe: 0.05 to 0.5%, one side of an aluminum alloy core material containing the balance of Al and inevitable impurities, Zn: 2.
A sacrificial anode skin material containing 0 to 10.0% and Mg ≦ 0.1%, the balance being Al and unavoidable impurities is clad, and the other surface of the aluminum alloy core material is Al-S
An aluminum alloy brazing sheet for forming a brazing tube having excellent brazing properties and corrosion resistance, wherein a brazing material made of an i-based or Al-Si-Zn-based alloy is clad. 3. The sacrificial anode skin material further contains In: 0.01.
2% or more, and Sn: 0.05 to 0.2%, one or more of them are added.
4. The aluminum alloy brazing sheet for forming a brazing tube according to any one of 3. 4. The brazing sheet according to claim 1, which is formed into a tubular shape by molding and brazing, wherein the sacrificial anode skin is positioned at the brazing portion, and the sacrificial anode skin is brazed. A brazing tube comprising a part of a part.