JP4861905B2 - Aluminum alloy brazing material and aluminum alloy brazing sheet - Google Patents

Description

  The present invention relates to an aluminum alloy brazing material and an aluminum alloy brazing sheet, and particularly to an aluminum alloy brazing sheet suitably used as a component of an automotive heat exchanger such as a radiator and a condenser, and to the production of this brazing sheet. It relates to an aluminum alloy brazing material.

Aluminum alloys are lightweight and have high thermal conductivity, and are therefore used in automotive heat exchangers such as radiators, condensers, evaporators, heaters, and intercoolers. Automotive heat exchangers are mainly manufactured by the brazing method. Usually, brazing is performed at a high temperature of about 600 ° C. using a brazing material of an Al—Si alloy.
Although there are various brazing methods, an NB method (nocorock brazing method) in which brazing in N ₂ gas using a fluoride-based flux which is a non-corrosive flux is generally used. Examples of the brazing alloy used in the NB method include Al—Si based brazing materials such as JIS 4343 alloy, JIS 4045 alloy, and JIS 4047 alloy.

An aluminum alloy heat exchanger such as a radiator manufactured by brazing is formed by integrally forming a corrugated fin (1) between a plurality of flat tubes (2) as shown in FIG. The flat tube has a structure in which both ends of the flat tube are opened in spaces formed by the plate (3) and the tank (4). Here, as the flat tube (2), a B-type tube obtained by processing a plate material into a shape as shown in FIG. 2 by roll molding or the like may be used.
When a B-type tube is used, as shown in FIG. 3, when the flat tube (2) is inserted into the tube hole formed in the plate (3), the gap portions (5, 6) indicated by an ellipse are illustrated. Formed as follows. These gaps need to be completely filled mainly by the brazing supplied from the plate. However, when a heat exchanger using a B-type tube is brazed, a phenomenon occurs in which the brazing supplied from the plate is sucked to the fin side by a capillary force through a groove formed in the B-type tube. (5, 6) does not reach the solder sufficiently, causing the brazing failure.

By adding Ti and Fe to the brazing filler metal, the brazing sheet for aluminum alloy brazing filler metal and aluminum heat exchanger aimed at improving the self-corrosion resistance by making the brazing filler potential noble and improving the viscosity when the brazing filler metal is melted It has been proposed (see, for example, Patent Document 1).
However, if the viscosity of the brazing material is improved, the fluidity of the brazing will be improved, and it will be difficult to suppress poor brazing at the joint between the tube and the plate. That is, it is considered that the melted plate wax flows into the core portion using the tube groove formed by molding as a passage, and the flow of the plate wax changes greatly depending on the viscosity of the wax.
(a) For example, in the case of a liquid having a very low viscosity, since it is smooth, the capillary force is small and the wax is difficult to be pulled to the core part.
(b) When the viscosity is increased, the capillary force is increased and the core portion is easily pulled. However, in this case, the plate brazing is less likely to remain at the root portion, which causes a brazing failure.
That is, in the conventional example of “enhanced wax viscosity”, the increase in viscosity is halfway, and the capillary force is increased as shown in (b) above.

Japanese Patent Laid-Open No. 02-34296

Thus, in the conventional technology, in the brazing of the heat exchanger for automobiles, particularly in the brazing of the heat exchanger using the B-type tube, it is not possible to sufficiently suppress the brazing failure at the joint portion of the tube and the plate. It was difficult.
The present invention has been made to solve this problem, and in an aluminum alloy brazing sheet, good brazing property can be obtained in brazing performed at about 600 ° C. It is an object of the present invention to provide a brazing material capable of reducing brazing defects at a joint and an aluminum alloy brazing sheet clad with the brazing material.

The above-described problems of the present invention have been realized by the following means.
(1) Si: 6 to 13% (mass%, the same applies hereinafter), Fe: 0.05 to 0.5%, Ti: 0.3 to 1.0%, Zr: 0.3 to 1 An aluminum alloy brazing material containing at least one of 0.0%, the balance being Al and inevitable impurities.
(2) An aluminum alloy brazing sheet characterized in that the aluminum alloy brazing material according to (1) is clad on one or both sides of the surface of an aluminum alloy sheet material having a core material.

  According to the present invention, good brazing performance can be obtained in brazing performed at about 600 ° C., and in particular, poor brazing can be reduced at the joint between the tube and the plate. As a result, it is possible to reduce the defective rate of brazing in the brazing assembly of the heat exchanger.

A preferred embodiment of the aluminum alloy brazing material of the present invention will be described in detail.
The reason for addition of component elements and the addition range of the aluminum alloy brazing material of the present invention will be described.
Si lowers the melting point of Al and increases the fluidity at the time of melting. The content of Si is in the range of 6 to 13% (hereinafter, “% of composition indicates mass%”), preferably 7 to 12%. If it is less than 6%, the effect is small, and if it exceeds 13%, the melting point of the brazing material becomes high and the fluidity is lowered. Moreover, since it becomes a hypereutectic composition, coarse primary crystal Si is produced | generated and the workability falls.
Fe has an effect of generating an Al—Fe compound in the matrix of the brazing material and increasing the viscosity of the molten brazing. The Fe content is 0.05 to 0.5%, preferably 0.1 to 0.4%. If it is less than 0.05%, a high-purity aluminum ingot must be used, resulting in an increase in cost. If it exceeds 0.5%, the Al—Fe-based compound that serves as a starting point of the cathode increases and the corrosion resistance decreases.

Ti has the effect of generating an Al ₃ Ti compound in the matrix of the brazing material and increasing the viscosity of the molten braze. The content of Ti is in the range of 0.3 to 1.0%. If the content is less than 0.3%, the effect is small, and if it exceeds 1.0%, a coarse primary crystal Al ₃ Ti compound is produced during casting. , Leading to a decrease in workability. More preferably, it is 0.4 to 0.8%.
Zr has an effect of generating an Al ₃ Zr compound in the matrix of the brazing material and increasing the viscosity of the molten braze. The content of Zr is in the range of 0.3 to 1.0%. If the content is less than 0.3%, the effect is insufficient. If the content exceeds 1.0%, the coarse primary crystal Al ₃ Zr compound is cast. To reduce the workability. More preferably, it is 0.4 to 0.8%.
In the present invention, if either Ti or Zr is added, the intended effect can be obtained, but in order to sufficiently increase the viscosity of the molten wax and improve the brazing property at the joint between the tube and the plate. It is particularly preferable to add both Ti and Zr.

Next, a preferred embodiment of the aluminum alloy brazing sheet of the present invention will be described.
The aluminum alloy brazing sheet of the present invention is obtained by cladding the aluminum alloy brazing material of the present invention described above on one or both surfaces of the core material or the sheet having the core material.
The aluminum alloy composition of the core material may be any aluminum alloy that is usually used for aluminum alloy brazing sheets, but is preferably an Al-Mn alloy such as JIS3003 alloy, an Al-Mn-Cu alloy, A high-strength, high-corrosion-resistant alloy such as an Al—Si—Mg alloy can be used.
Examples of the aluminum alloy sheet material before clad with the brazing material include those having a structure composed of a core material-sacrificial anode material layer, an intermediate material layer-core material-sacrificial anode material layer, etc., in addition to a bare material composed only of a core material. The clad of the brazing material may be either single-sided or double-sided in the case of a bare material with respect to the aluminum alloy sheet material. Further, when a sacrificial anode material layer is provided, it is preferably performed on the opposite surface.
In the aluminum alloy brazing sheet of the present invention, the clad rate of the brazing material layer is preferably 3% or more, more preferably 5 to 15% with respect to the thickness of the core material.

Next, the present invention will be described in more detail based on examples, but the present invention is not limited thereto.
Each brazing filler metal having the alloy composition shown in Table 1 was cast by die casting, chamfered on both sides, finished, and rolled to a thickness of 5 mm by hot rolling. Next, JIS3003 alloy was cast as a core material by die casting, subjected to a homogenization treatment at 600 ° C. × 3 h, and then face-finished to a thickness of 45 mm. Thereafter, a brazing material was combined on one side of the core material at a cladding rate of 10%, and crimped by hot rolling at 500 ° C. to obtain a 3.5 mm two-layer cladding material. Thereafter, cold rolling was performed to obtain a 1.2 mm plate material, and final annealing at 380 ° C. × 2 h was performed to obtain an O tempered material.

Next, the produced two-layer clad plate material was used as a test material, and the brazing property and the external corrosion resistance were evaluated by the following methods. The results are shown in Table 2.
(1) Brazability:
As shown in FIG. 4, a sample in which a groove 8a (depth 1.5 mm) was formed in the center in the width direction by forming using a bare material (8) of 0.3 mm thick JIS3003 alloy was produced. Then, a test piece for brazing test was prepared by combining the corrugated JIS3003 alloy fin (9) and the U-shaped specimen (7). This was immersed in a solution in which 5% fluoride flux was suspended, dried at 200 ° C. and brazed by a noclock brazing method of 600 ° C. × 3 min. Thereafter, microscopic observation of the cross section as shown in FIG. 5 was performed, and the throat thickness of the fillet (10) formed at the joint between the specimen (7) and the JIS 3003 alloy bare material (8) (white arrow in the fillet) (Reference: Aluminum Brazing Handbook P.129 Light Metal Welding Structure Association).
When the throat thickness is 150 μm or more, the brazing property is good, “◯”, and when the throat thickness is less than 150 μm, or when the fillet is not formed, the brazing property is insufficient.

(2) External corrosion resistance evaluation:
After the brazing heat of 600 ° C. × 3 min, the core material side was sealed in order to evaluate the corrosion resistance of the brazing material side, a CASS test (JIS H8681) 500 h was carried out with a single plate, and the maximum pitting corrosion depth was measured. When the maximum pitting depth is less than 300 μm, the external corrosion resistance is “good”, and when the depth is 300 μm or more, the external corrosion resistance is insufficient.

(3) Formation of coarse intermetallic compounds in the brazing filler metal:
In the obtained brazing material, the cross section of the L-LT surface was micro-observed with an optical microscope, and the production of intermetallic compounds and the particle size thereof were examined. Note that a surface formed in the rolling direction (L direction) and a direction parallel to the rolling surface and perpendicular to the L direction (LT direction) is an L-LT surface.
The case where the intermetallic compound having a particle size of 50 μm or more was not produced was designated as “◯”, and the produced one was designated as “X”.

As is apparent from Table 2, the test material No. Nos. 1 to 6 were excellent in brazing property and external corrosion resistance, and no formation of coarse intermetallic compounds was observed in the brazing material.
On the other hand, test material No. which is a comparative example. For 7, 9, and 12 (Ti and Zr are less than the specified range), the required size of the fillet throat was not obtained, and the brazability was insufficient. In addition, test material No. No. 10 (Fe exceeds the specified amount) had a large amount of Al—Fe-based compound in the brazing filler metal, so that the external corrosion resistance deteriorated. No. Nos. 8, 11, and 12 had a large amount of Si, Ti, and Zr added to the brazing material, so primary crystals were formed during casting, and coarse intermetallic compounds remained in the brazing material of the final specimen. It remained.

It is a perspective view of the heat exchanger made from an aluminum alloy. It is a perspective view of a B type tube. It is the top view which inserted the flat tube in the tube hole of the plate. It is a perspective view of a test piece for brazing test. It is a partial expanded sectional view of the test piece for a test after Nocolok brazing addition heat.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Fin 2 Flat tube 3 Plate 4 Tank 5 Crevice part 6 Crevice part 7 Test material 8 Alloy bear material 9 Fin 10 Fillet

Claims (2)

  Si: 6 to 13% (mass%, the same shall apply hereinafter), Fe: 0.05 to 0.5%, Ti: 0.3 to 1.0%, Zr: 0.3 to 1.0% An aluminum alloy brazing material containing at least one of the above, and the balance being Al and inevitable impurities.   An aluminum alloy brazing sheet characterized in that the aluminum alloy brazing material according to claim 1 is clad on one side or both sides of the surface of an aluminum alloy sheet material having a core material.

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