JP2002294378A - Aluminum alloy extrusion tube for producing header tank - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an aluminum alloy extrusion tube for producing a header tank in a heat exchanger, and a brazing filler metal-coated aluminum alloy extrusion tube obtained by coating the surface of the same aluminum alloy extrusion tube with a brazing filler metal composition containing brazing filler metal powder, flux and a binder. SOLUTION: The aluminum alloy extrusion tube for producing a header tank has a composition containing 0.5 to 1.3% Mn, 0.5 to 1.2% Si, 0.3 to 1% Cu, 0.1 to 0.3% Ti and 0.2 to 0.5% Zn, and, if required, containing 0.01 to 0.05% Zr, and the balance Al with inevitable impurities. The brazing filler metal-coated aluminum alloy extrusion tube is obtained by coating the surface of the same aluminum alloy extrusion tube with a brazing filler metal composition containing brazing filler metal powder, flux and a binder.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an aluminum alloy extruded tube for manufacturing a header tank in a heat exchanger, and a brazing material composition containing a brazing powder, a flux and a binder on the surface of the aluminum alloy extruded tube. The present invention relates to a brazing material-coated aluminum alloy extruded tube formed by applying an aluminum alloy.

[0002]

2. Description of the Related Art In general, as shown in FIG. 3, a heat exchanger is made of header tanks 5, 5 and an aluminum alloy provided between the header tanks 5, 5 at intervals in parallel with each other. Many tubes 1 and tubes 1
And a corrugated fin 6 provided between the tube 1. And the internal space of each tube 1 and the internal space of the header tank 5 are communicated, and the refrigerant is circulated in the internal space of the header tank 5 and the internal space of each tube 1,
Heat can be exchanged efficiently through the fins 6.

In order to manufacture this heat exchanger, first, FIG.
A brazing material-coated aluminum alloy extruded tube in which a brazing material composition layer 2 is formed by applying a brazing material composition to the surface of an aluminum alloy extruded tube 3 provided with a plurality of slots 7 on the side as shown in the perspective view of FIG. A brazing material-coated aluminum alloy extruded tube 55 having a plurality of slots 7 provided on its side face is fixed in parallel at intervals so that the slots 7 of the extruded tube 55 are opposed to each other. A tube 1 having a plurality of refrigerant passage holes (not shown) is inserted into a plurality of slots 7 and fins 6 made of a brazing sheet are arranged between the tubes 1 and assembled. The obtained assembly is put into a heating furnace. Charge and heat.

When such heating is performed, the corrugated fins 6 are brazed and fixed between the tubes 1 by the brazing material applied to the surface, and at the same time, the brazing material composition layer 2 of the brazing material-coated aluminum alloy extruded tube 55 is formed. The contained brazing material melts and penetrates into the slots of the aluminum alloy extruded tube in which the tube is inserted to form a brazed joint (hereinafter, referred to as a fillet portion), whereby the aluminum alloy extruded tube 55 and the tube 1 are formed. Is fixed by brazing, and a heat exchanger including the fins 6, the tube 1, and the header tank 5 is produced. FIG. 4 is a partial cross-sectional view of the joint between the tube 1 and the header tank 5 in the heat exchanger thus manufactured, and 8 denotes a fillet.

[0005] As the brazing filler metal-coated aluminum alloy extruded pipe 55 serving as a header tank, for example, an aluminum alloy extruded pipe 3 having a square cross section as shown in the perspective view of FIG. 1 is used, and a brazing material composition is coated on the surface thereof. The brazing material composition layer 2 is formed by coating, and the brazing material-coated aluminum alloy extruded tube serving as a header tank is formed on the surface of an aluminum alloy extruded tube 4 having a circular cross section as shown in FIG. Aluminum alloy extruded tube 55 coated with brazing material having layer 2 formed thereon
'Can also be used.

The brazing material-coated aluminum alloy extruded tube 5
5, the aluminum alloy extruded tube 3 having a square cross section and the aluminum alloy extruded tube 4 having a circular cross section that constitutes a brazing material-coated aluminum alloy extruded tube 55 'are both Al-Mn-based aluminum having excellent extrudability and strength. The tube 1 is made of a pure aluminum-based alloy having excellent extrudability and a purity of 99.50% or more, for example, JIS1050. As the brazing filler metal powder contained in the brazing filler metal composition layer 2, an Si powder, an Al—Si alloy powder containing 5% to 60% of Si and the balance of Al and inevitable impurities, or Si:
An Al-Si-Zn-based alloy powder containing 5 to 60% and Zn: 2 to 30%, the balance being Al and unavoidable impurities is used.

[0007]

However, the conventional heat exchanger manufactured using such an aluminum alloy extruded tube, tube and brazing material is certainly excellent in corrosion resistance,
When used in a real environment, the corrosion resistance is still insufficient, and particularly the corrosion resistance of the fillet, which is the joint of the header tank and the tube made of aluminum alloy extruded pipe with the brazing material, is poor, and therefore the service life of the heat exchanger Therefore, there is a demand for a heat exchanger having a shorter working life.

[0008]

Means for Solving the Problems Accordingly, the present inventors have
From the viewpoints described above, the corrosion resistance is further improved,
Research was conducted to produce a long-life heat exchanger.
As a result, in mass% (hereinafter,% indicates mass%), M
n: 0.5 to 1.3%, Si: 0.5 to 1.2%, C
u: 0.3-1%, Ti: 0.1-0.3%,
Furthermore, it contains Zn: 0.2-0.5%, further contains Zr: 0.01-0.05% as needed, and the remainder is A
An aluminum alloy extruded tube having a composition consisting of l and inevitable impurities is used as an extruded tube for producing a header tank. The header tank and the tube are made of a composition containing 5% to 60% of Si and the balance consisting of Al and inevitable impurities. Al-Si alloy brazing material or Si: 5-60%, Z
When a heat exchanger is manufactured using an Al-Si-Zn-based alloy brazing material containing n: 2 to 30% and the balance being Al and unavoidable impurities, a header tank in the obtained heat exchanger The research results show that the corrosion resistance of the tube and the fillet portion, which is the joint between the tube and the header tank and the tube, is further improved, and the service life of the heat exchanger is prolonged.

The present invention has been made based on the above research results, and (1) Mn: 0.5 to 1.3%;
Si: 0.5 to 1.2%, Cu: 0.3 to 1%, Ti:
0.1-0.3%, Zn: 0.2-0.5%,
An aluminum alloy extruded tube for producing a header tank having a composition consisting of Al and inevitable impurities, (2) Mn: 0.5 to 1.3%, Si: 0.5 to
1.2%, Cu: 0.3-1%, Ti: 0.1-0.3
%, Zn: 0.2-0.5%, Zr: 0.01-0.0
An aluminum alloy extruded tube for producing a header tank having a composition containing 5% and the balance consisting of Al and unavoidable impurities.

[0010] The aluminum alloy extruded tube for manufacturing the header tank is provided with a slot for inserting a tube on a side surface thereof, and contains a brazing filler metal powder, a flux and a binder on at least the outer surface portion on the side where the slot is provided. A brazing material-coated aluminum alloy extruded tube is produced by applying the brazing material composition, and a heat exchanger is produced using the brazed material-coated aluminum alloy extruded tube. Therefore, the present invention provides (3) an aluminum alloy extruded tube for manufacturing the header tank according to the above (1),
At least the outer surface of the portion provided with a slot for inserting a tube is provided with an Al-Si alloy brazing powder, a flux and a binder containing 5% to 60% of Si and the balance of Al and inevitable impurities. A brazing material-coated aluminum alloy extruded tube for producing a header tank formed by applying a brazing material composition to be contained, and (4) an aluminum alloy extruded tube for producing a header tank described in (2) above, wherein at least a tube S on the outer surface of the portion where the slot for inserting
i: To manufacture a header tank formed by applying a brazing filler metal composition containing 5 to 60%, the balance being Al and inevitable impurities, containing an Al-Si alloy brazing powder, a flux and a binder. (5) In the aluminum alloy extruded tube for manufacturing the header tank according to (1), at least the outer surface of a portion provided with a slot for inserting a tube has Si: 5-60%, Zn: 2
Al-Si-Zn-based alloy brazing powder containing about 30%, with the balance being Al and unavoidable impurities,
Extruded brazing material-coated aluminum alloy tube for producing a header tank formed by applying a brazing material composition containing a flux and a binder, (6) Extruded aluminum alloy tube for producing the header tank described in (2) above , At least on the outer surface of a portion provided with a slot for inserting a tube, Si: 5 to 60%, Z
n: 2 to 30%, the remainder being a header tank formed by applying an Al-Si-Zn-based alloy brazing powder having a composition of Al and unavoidable impurities, a brazing material composition containing a flux and a binder. It is characterized by a brazing material-coated aluminum alloy extruded tube for production.

The brazing material composition layer formed on the outer surface of the aluminum alloy extruded tube for manufacturing the header tank according to the present invention comprises a fluoride-based flux (eg, LiF, KF, CaF ₂ , AlF) together with the brazing material powder. ₃ , SiF ₄
And KA which is a complex compound of the above fluoride
such lF _4, KAlF _5), were mixed together with a binder resin and a solvent to prepare a slurry paste can be formed by applying the same.

Next, the reason why the component compositions of the aluminum alloy extruded tube, tube and brazing material for manufacturing the header tank of the present invention are limited as described above will be described. A. Extruded aluminum alloy tube as header tank Mn: Mn crystallizes or precipitates on the substrate as an intermetallic compound and has the effect of improving the strength after brazing, but if its content is less than 0.5%, the desired effect is obtained. On the other hand, when Mn is contained in an amount of more than 1.3%, it is dispersed as a coarse Al-Mn-based intermetallic compound in the base material and extrudability is increased in order to increase deformation resistance at high temperatures. Is not preferred because it significantly lowers the productivity and inhibits productivity. Therefore, Mn contained in the header tank is 0.1.
It was set to 5 to 1.3%. A more preferable range of the Mn content is 1.1 to 1.3%.

Si: has the effect of increasing the potential by making a solid solution of a large amount of Si, improving the brazing property, and forming a good fillet portion to improve the strength after brazing. Is less than 0.5%, the desired effect cannot be obtained.
If it is contained more, it lowers the melting point of the alloy and causes excessive melting during brazing, further lowers the extrudability, and the potential of the header tank becomes noble with respect to the tube, which hinders the corrosion resistance of the tube. Not preferred. Therefore, Si is set to 0.5 to 1.2%. A more preferable range of the Si content is 0.9 to 1.1%.

Cu: Cu has the effect of making the potential inside the header tank nobleer than the surface after brazing and further improving the strength after brazing by solid solution in the base material. This is because the diffusion speed of the liquid solder melted during brazing is significantly increased compared to solids, so the diffusion of Cu from the aluminum alloy extruded tube serving as the header tank to the liquid solder is activated and the potential of the liquid solder becomes low. This Cu
The liquid solder, which is suppressed from diffusing into the liquid solder and causing the potential to become low, flows into the gap formed by the tube and the slot of the header tank, thereby forming a fillet portion having excellent corrosion resistance. On the other hand, the concentration of Cu near the surface of the header tank after brazing becomes lower as it is closer to the surface because Cu diffuses into the liquid braze, and becomes higher as it goes inside, and the potential becomes noble. The concentration gradient of Cu, which becomes more noble as it goes, forms a potential gradient in which the potential of the header tank becomes higher as going from the surface to the inside, so that the corrosion form becomes planar and the inside of the corrosion becomes Progress is suppressed. However, if the Cu content is less than 0.3%, the desired effect cannot be obtained, so that it is not preferable. On the other hand, if the Cu content is more than 1%, the potential becomes noble and the corrosion resistance of the tube is inhibited, which is not preferable. . Therefore, the content of Cu is set to 0.3 to 1%.
A more preferred range for the Cu content is 0.4-0.8%.

Ti: Ti is distributed in the form of a layer in the base material during extrusion molding. Corrosion progresses preferentially in a portion having a low Ti concentration because the potential becomes lower than that in a portion having a high Ti concentration, and the form of corrosion becomes layered and deep. It is added because it has the effect of improving the corrosion resistance due to the suppression of the occurrence of pitting corrosion and has the effect of improving the strength by crystallization or precipitation as an intermetallic compound. No effect, while 0.3
%, It is not preferable because a large intermetallic compound is easily formed and the extrusion processability is reduced. Therefore, Ti is set to 0.1 to 0.3% (more preferably 0.16 to 0.18%).

Zn: Zn is added in order to lower the potential of the low-concentration portion of Ti, promote the effect of layered corrosion by Ti, and further improve the corrosion resistance.
If the content is less than 0.5%, the desired effect cannot be obtained. On the other hand, if the content exceeds 0.5%, the corrosion rate increases and the corrosion resistance becomes poor, which is not preferable. Therefore, the content of Zn is 0.1.
It was set to 2-0.5%.

Zr: Zr is necessary because it has the effect of flattening the crystal grains generated during brazing, forming a layer of corrosion, improving corrosion resistance, and improving the strength by crystallization or precipitation as an intermetallic compound. However, if the content is less than 0.01%, the desired effect cannot be obtained. On the other hand, if the content exceeds 0.05%, a huge intermetallic compound is likely to be formed. It is not preferable because the property is lowered. Therefore, Zr: 0.01 to
It was set to 0.05%.

B. The brazing filler metal powder contained in the brazing filler metal composition Si: Si has an action of diffusing into the header tank and forming a liquid-phase solder, but if its content is less than 5%, poor brazing due to shortage of the liquid-phase solder is caused. On the other hand, if the content of Si exceeds 60%, significant erosion of the header tank occurs, which is not preferable. Therefore, Si is set to 5 to 60%. S
A more preferable range of the i content is 7 to 40%.

Zn: Zn diffuses into the header tank to form a sacrificial anode layer, but if its content is less than 2%, the effect of the sacrificial anode layer decreases, which is not preferable.
If the content exceeds 0%, the corrosion resistance of the fillet formed at the joint between the tube and the header tank is undesirably reduced. Therefore, Zn was set to 2 to 30%. A more preferable range of the Zn content is 5 to 20%.

C: Tube The tube used for making the heat exchanger of the present invention has the same excellent extrudability as in the prior art. Purity: 99.50%.
The above pure aluminum alloys, for example, 1N99, 1N90, 1085, 1080, 107 specified in JIS
0, 1060, and 1050 can be used.

[0021]

BEST MODE FOR CARRYING OUT THE INVENTION A billet is produced by melting and casting an Al alloy, and the billet is extruded to a width of 22.
mm, height: 16 mm, thickness: 1.6 mm, to produce rectangular extruded hollow pipes, and dimensions of these rectangular extruded hollow pipes: width: 16.1 mm, thickness: 2.1 mm The aluminum alloy extruded tubes 1 to 9 of the present invention, the comparative aluminum alloy extruded tubes 1 to 4 and the conventional aluminum alloy extruded tubes for producing a header tank having the component composition shown in Table 1 by forming a slot having did.

[0022]

[Table 1]

Further, as the brazing filler metal powder, the average particle size is 2
A brazing filler metal powder having a composition of 0 μm and having the composition shown in Table 2 was prepared. Further, KAlF ₄ powder as a flux, isopropyl alcohol (IPA) as a solvent, and an acrylic resin binder as a binder were prepared. Powder, flux, solvent and binder,
Brazing filler metal powder: KAlF ₄ powder: acrylic resin binder: isoproalcohol (IPA) = 100: 25: 1
By blending and mixing so as to have a mass ratio of 4: 100, slurry paste brazing compositions A and B having a mass% shown in Table 2 were prepared.

[0024]

[Table 2]

Furthermore, pure Al of JIS1050 is melted and cast to produce billets, and these billets are homogenized under ordinary conditions and then extruded to have eight refrigerant passage holes, width: 16 mm To produce a flat extruded tube having dimensions of thickness: 2 mm, wall thickness: 0.35 mm,
This was prepared as a tube.

The aluminum alloy extruded tubes 1 to 9 of the present invention having the component compositions shown in Table 1 and the comparative aluminum alloy extruded tube 1
After forming slots in the aluminum alloy extruded tube and the conventional aluminum alloy extruded tube, the brazing material composition of the slurry-like paste containing the brazing material powder having the component composition shown in Table 2 was obtained by converting AB into 100 g / m ^{2 in} terms of the brazing material powder. It is applied to produce a brazing material-coated aluminum alloy extruded tube having a brazing material composition layer, and the prepared tube is inserted into a slot of the brazing material-coated aluminum alloy extruded tube.
By heating at 0 ° C. for 3 minutes, an assembled joint structure comprising a header tank, a tube, and a fillet shown in FIG. 4 was produced.

In this way, the aluminum alloy extruded tubes 1 to 9 of the present invention, the comparative aluminum alloy extruded tubes 1 to 4 and the conventional aluminum alloy extruded tube are used as a header tank, and FIG. In order to evaluate the corrosion resistance of the assembled joint structure shown in FIG.
The SWAAT test is repeated for 30 days, in which a cycle of moistening at 50 ° C. for 90 minutes is performed after spraying the acidic artificial seawater for 30 minutes, and the corrosion of the header tank, the tube near the header tank, and the fillet portion, which is the joint between the tube and the header tank, is performed. The degree was observed, and the results are shown in Table 3. The degree of corrosion of the header tank was as follows: x for through-hole generation, x for deep pitting (deep pitting of 1/2 or more of header tank thickness), and △ for shallow pitting (1/2 of header tank thickness).
The occurrence of shallow pitting (less than 2) is indicated by ○, and the occurrence of extremely shallow pitting (extremely shallow pitting of less than 1/3 of the header tank thickness) is indicated by 、.
Regarding the degree of corrosion of the tube, × indicates the occurrence of through holes, × indicates deep pitting (deep pitting of 1/2 or more of the tube thickness), and 浅 shallow pitting (shallow pitting less than 1/2 of the tube thickness). ○
Extremely shallow pitting (extremely shallow pitting less than 1/3 of tube thickness)
The occurrence is indicated by ◎, and the degree of corrosion of the fillet, which is the joint between the tube and the header tank, is indicated by ×, the occurrence of through holes penetrating from the inside to the outside of the fillet, and deep pitting (from the outer fillet to the inner fillet) The occurrence of deep pits of 1/2 or more of its length) is marked with Δ, the occurrence of shallow pits (shallow pits of less than 1/2 of the length from the outer fillet to the inner fillet) is marked with ○, and extremely shallow pits The results are shown in Table 3 where the occurrence of (extremely shallow pitting corrosion less than 1/3 of the length from the outer fillet portion to the inner fillet portion) was evaluated as ◎.

[0028]

[Table 3]

[0029]

From the results shown in Tables 1 to 3, the aluminum alloy extruded tubes 1 to 9 of the present invention are evaluated as ◎ or ○ in the degree of corrosion of the tube near the header tank, the header tank, and the fillet portion of the tube and the header tank. However, the degree of corrosion of the tube near the header tank, the header tank, and the fillet portion of the tube and the header tank formed by the conventional aluminum alloy extruded tube and the comparative aluminum alloy extruded tubes 1 to 4 is either Δ or ×. It can be seen from the inclusion that the corrosion resistance is poor.

As described above, according to the present invention, by combining this header tank with a predetermined tube and brazing material, it is possible to provide a joint structure of a heat exchanger having excellent corrosion resistance, which has an industrially useful effect. Things.

[Brief description of the drawings]

FIG. 1 is a perspective view of a brazing material-coated aluminum alloy extruded tube for manufacturing a header tank of the present invention.

FIG. 2 is a perspective view of a brazing filler metal-coated aluminum alloy extruded tube for manufacturing the header tank of the present invention.

FIG. 3 is a perspective view of a conventional heat exchanger.

FIG. 4 is a cross-sectional view near a joint between a header tank and a tube.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Tube 2 Brazing material composition layer 3 Extruded tube 4 Extruded tube 5 Header tank 6 Fin 7 Slot 8 Fillet part 55 Brazed material-coated aluminum alloy extruded tube 55 'Brazed material-coated aluminum alloy extruded tube

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) F28F 21/08 F28F 21/08 A F term (Reference) 3H111 AA01 BA05 BA34 CB03 CB18 CB21 DA08 DB27 EA04 3L103 AA12 DD15 DD55 DD82

Claims (4)

[Claims] (1) In terms of mass% (hereinafter,% indicates mass%), M
n: 0.5 to 1.3%, Si: 0.5 to 1.2%, C
u: 0.3-1%, Ti: 0.1-0.3%, Zn:
An aluminum alloy extruded tube for producing a header tank, comprising 0.2 to 0.5% and a balance of Al and unavoidable impurities. 2. Mn: 0.5-1.3%, Si: 0.5-
1.2%, Cu: 0.3-1%, Ti: 0.1-0.3
%, Zn: 0.2-0.5%, Zr: 0.01-0.0
An aluminum alloy extruded tube for producing a header tank, wherein the extruded tube contains 5% and a balance of Al and unavoidable impurities. 3. An aluminum alloy extruded tube for manufacturing a header tank according to claim 1, wherein at least the outer surface of a portion provided with a slot for inserting a tube contains Si: 5 to 60%. And the rest is A
Extrusion of a brazing filler metal coated aluminum alloy for producing a header tank, characterized by applying a brazing filler metal composition containing an Al-Si alloy brazing powder, a flux and a binder, the composition comprising an aluminum alloy and unavoidable impurities. tube. 4. An aluminum alloy extruded tube for manufacturing a header tank according to claim 1, wherein at least the outer surface of a portion provided with a slot for inserting a tube has a Si content of 5 to 60% and Zn. : 2 to 30%
A header tank characterized by being coated with an Al-Si-Zn-based alloy brazing powder having a composition consisting of Al and unavoidable impurities, a flux and a binder. Aluminum alloy extruded tube coated with brazing material.