JP5180565B2 - Aluminum alloy brazing sheet for heat exchanger - Google Patents

Description

  The present invention relates to a brazing sheet used for a heat exchanger for automobiles, and more particularly to an aluminum alloy brazing sheet for a heat exchanger excellent in strength and corrosion resistance after brazing.

  A heat exchanger such as a condenser or an evaporator mounted on an automobile is formed by molding, assembling, and brazing a clad material or brazing sheet made of an aluminum alloy. In recent years, this aluminum alloy brazing sheet has been reduced in thickness from a conventional plate thickness of 0.3 to 0.5 mm to a plate thickness of 0.2 mm or less, for example, for tube materials in order to reduce the weight of a heat exchanger. Accordingly, there is a demand for higher strength and higher corrosion resistance.

For example, Patent Document 1 discloses a conventional sacrificial anode material made of an Al-Zn alloy on one surface of a core material made of an Al-Mn-Cu alloy, and a conventional technique relating to an aluminum alloy brazing sheet for a heat exchanger having excellent corrosion resistance. A brazing material made of an Al—Si alloy is laminated on the surface, and the corrosion resistance is improved by the sacrificial anticorrosive action of the Al—Zn alloy.
Japanese Patent Laying-Open No. 2005-232506 (Claim 1)

  The prior art provides a sacrificial anticorrosive action by forming a sacrificial anode layer made of an Al—Zn alloy on the corrosive environment side with an Al—Mn—Cu alloy as a core material. When alloys with different compositions are clad and clad, the contained elements (Cu, Zn) diffuse by heat treatment (hot rolling, soft annealing) and brazing treatment during the manufacturing process of the brazing sheet. That is, Zn in the sacrificial anode layer diffuses into the core material, and Cu in the core material diffuses into the sacrificial anode layer and the brazing material layer. Therefore, in the thickness direction of the brazing sheet, as shown in FIG. The Cu has a concentration distribution that decreases or becomes constant in one direction, and Cu decreases or becomes constant in both directions with the vicinity of the center of the core plate thickness being the apex. Further, the brazing material layer flows by the brazing process and hardly remains on the surface of the brazing sheet. Since Cu makes the potential of the aluminum alloy noble and Zn makes the potential of the aluminum alloy base, the potential gradient in this brazing sheet is the most noble in the vicinity of the center of the core plate thickness as shown in FIG. It becomes. In this structure, when corrosion (pitting corrosion) from the sacrificial anode layer side progresses to the center of the core plate thickness, the potential deeper than the center of the core plate thickness becomes lower than the center of the core plate thickness. It is thought that. For this reason, when this brazing sheet is exposed to a thin wall and a severe corrosive environment, there is a fear of early through-hole formation.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide an aluminum alloy brazing sheet for a heat exchanger that maintains high corrosion resistance and high strength even when it is thinned.

  In order to solve the above-mentioned problems, the present inventors set the layer on the outside of the heat exchanger, which is a corrosive environment, as a sacrificial anode layer with respect to the core material by making the potential lower than the core material, as in the prior art, On the contrary, the layer on the inner side of the heat exchanger in contact with is made to have a sacrificial anticorrosive effect even deeper than the center of the core plate thickness by making the potential nobler than the core material. As a result, a method of inventing a method of applying a potential gradient so that the potential becomes noble from the outside to the inside by controlling the concentration distribution of Cu and Zn in the aluminum alloy that is a material forming each layer. (See FIG. 1).

That is, the aluminum alloy brazing sheet for a heat exchanger according to claim 1 is made of a core material, a sacrificial anode layer disposed on one surface side of the core material, and an Al—Si based alloy disposed on the other surface side of the core material. An aluminum alloy brazing sheet for a heat exchanger provided with a brazing filler metal layer, wherein the core material includes Si: 0.3 to 1.5 mass%, Mn: 0.5 to 1.8 mass%, Mg: 0.00. Containing 0.5 to 0.5% by mass, Ti: 0.05 to 0.35% by mass, the balance being made of Al and inevitable impurities, the sacrificial anode layer being 0.03 to 1.5% by mass, Mn : 1.8% by mass or less, Zn: 2.5 to 7.0% by mass, the balance is made of Al and inevitable impurities, and the brazing filler metal layer is Si: 7.0 to 13.0% by mass. , Cu: 3.0 wt% or less and containing more Cu concentration of the core Characterized in that the balance of Al and unavoidable impurities.

  In this way, the core material has a three-layered structure in which the core material is sandwiched between the sacrificial anode layer on the outer side exposed to the atmosphere and the brazing material layer on the inner side in contact with the refrigerant, and in the aluminum alloy that is a material forming each layer By controlling the concentration distribution of Cu and Zn, a potential gradient can be applied so that the potential becomes noble from the outside to the inside. As a result, the sacrificial anticorrosion effect can be maintained even when pitting corrosion reaches deeper than the central part of the core plate thickness, and the life can be extended as compared with the prior art.

  Furthermore, the aluminum alloy brazing sheet for heat exchangers according to claim 2 is the aluminum alloy brazing sheet for heat exchangers according to claim 1, wherein the core material is further 1.0% by mass or less and Cu in the brazing material layer. It contains Cu below the content.

  Thus, when the core material contains a specified amount of Cu, the strength and corrosion resistance of the aluminum alloy brazing sheet for heat exchanger can be further improved.

  Furthermore, the aluminum alloy brazing sheet for heat exchangers according to claim 3 further includes a layer made of a brazing material on the surface of the aluminum alloy brazing sheet for heat exchangers according to claim 1 or 2 on the sacrificial anode layer side. It is characterized by that.

  As described above, since the brazing material layer is also provided on the outer side, it is possible to braze and join with a plate material that does not include the brazing material layer, such as a bare fin material.

  According to the aluminum alloy brazing sheet for a heat exchanger according to claim 1, high corrosion resistance and high strength can be maintained for a long time even if the thickness is reduced. This is particularly effective when it is important to prevent corrosion from the atmosphere, such as capacitors and evaporators.

  According to the aluminum alloy brazing sheet for a heat exchanger according to claim 2, high corrosion resistance and high strength can be maintained for a long period of time even when the thickness is reduced.

  According to the aluminum alloy brazing sheet for a heat exchanger according to claim 3, high corrosion resistance and high strength can be maintained over a long period of time even when the thickness is reduced, and further, the thickness is reduced to the extent that there is no brazing filler metal layer. By brazing and joining the plate material, a heat exchanger with a lighter weight can be formed.

Hereinafter, the best mode for realizing the aluminum alloy brazing sheet for a heat exchanger according to the present invention will be described.
FIG. 1 is a diagram showing Cu and Zn concentration distribution and potential gradient in an aluminum alloy brazing sheet for a heat exchanger according to the present invention, wherein (a) is a Cu and Zn concentration distribution diagram, and (b) is a potential gradient diagram. It is.

In the aluminum alloy brazing sheet for a heat exchanger according to the present invention, a sacrificial anode layer is clad on one surface of a core material made of an aluminum alloy, and a brazing material layer is clad on the other surface. When producing a heat exchanger using the aluminum alloy brazing sheet for a heat exchanger according to the present invention, the brazing material layer is on the heat exchanger inner side (refrigerant passage side), and the sacrificial anode layer is on the heat exchanger outer side (atmosphere side). )
That is, as shown in FIGS. 1 (a) and 1 (b), the aluminum alloy brazing sheet for a heat exchanger according to the present invention has a sacrificial anode layer, a core material, and a brazing material from the outside in the thickness direction (horizontal axis) A three-layer structure is formed in the order of the material layers (outflow after brazing treatment). As shown in FIG. 1A, the Cu and Zn concentration distribution in each layer is such that Cu decreases or becomes constant in one direction from the inner side, and Zn decreases or becomes constant in one direction from the outer side. By controlling, as shown in FIG. 1B, the potential is always noble from the outside to the inside. In addition, since the heat exchanger to which the aluminum alloy brazing sheet for heat exchangers according to the present invention is applied uses a non-corrosive refrigerant, corrosion from the inner side hardly occurs.

  Below, each element which comprises the aluminum alloy brazing sheet for heat exchangers which concerns on this invention is demonstrated.

[Heart material]
The core material is Si: 0.3 to 1.5 mass%, Mn: 0.5 to 1.8 mass%, Mg: 0.05 to 0.5 mass%, Ti: 0.05 to 0.35 mass% And the balance consists of Al and inevitable impurities. Further, the core material may further contain Cu of 1.0% by mass or less and Cu concentration of the brazing material layer or less. In addition, although the thickness of the core material in the aluminum alloy brazing sheet for heat exchangers according to the present invention is not particularly limited, it is preferably 0.05 to 0.4 mm.

(Core material Si: 0.3 to 1.5 mass%)
Si has the effect of improving the strength after brazing, and particularly when coexisting with Mg and Mn, the strength after brazing is further increased by the formation of Mg-Si intermetallic compounds and Al-Mn-Si intermetallic compounds. Can be increased. If it is less than 0.3% by mass, the effect is small. On the other hand, when the content exceeds 1.5 mass%, the core material is melted due to a decrease in melting point of the core material and an increase in the low melting point phase. Therefore, the Si content in the core material is set to 0.3 to 1.5 mass%.

(Core material Mn: 0.5 to 1.8% by mass)
Mn has an effect of improving the strength after brazing, and the strength after brazing can be increased by increasing the content. Moreover, since it has the function of making the potential noble, the corrosion resistance is improved. If it is less than 0.5% by mass, these effects are small. On the other hand, if it exceeds 1.8% by mass, a coarse intermetallic compound is formed, which tends to cause a decrease in formability and corrosion resistance. Therefore, the Mn content in the core is 0.5 to 1.8% by mass.

(Core material Mg: 0.05 to 0.5 mass%)
Mg has the effect of improving the strength after brazing, and the effect is small at less than 0.05% by mass. However, on the other hand, Mg has the effect of lowering the flux brazing property, so when it exceeds 0.5 mass%, Mg diffuses to the brazing material layer and the brazing material on the sacrificial anode layer side during brazing, Brazing performance is significantly reduced. Therefore, the content of Mg in the core material is 0.05 to 0.5% by mass.

(Core material Ti: 0.05 to 0.35 mass%)
Ti forms a Ti—Al compound in an aluminum alloy and is dispersed in a layered manner. Since the potential of the Ti—Al compound is noble, the corrosion form is layered, and there is an effect that it is difficult to progress to corrosion (pitting corrosion) in the depth direction. If it is less than 0.05% by mass, the layering effect of the corrosion form is small, and if it exceeds 0.35% by mass, formability and corrosion resistance are reduced due to the formation of coarse intermetallic compounds. Therefore, the Ti content in the core material is 0.05 to 0.35 mass%.

(Core material Cu: 1.0% by mass or less and Cu concentration of brazing filler metal layer or less)
Cu has the effect of improving strength after brazing. Moreover, since it has the function of making the potential noble, the corrosion resistance is improved. On the other hand, if it exceeds 1.0% by mass, burning may occur as the melting point decreases. Also, if the Cu concentration of the brazing material layer is exceeded, the potential near the center of the plate thickness becomes noble with respect to the brazing material layer side (inside) of the core material. Promoted. Therefore, the content of Cu in the core material is 1.0% by mass or less and is equal to or less than the Cu concentration of the brazing material layer. In the core material, since Cu diffuses from the laminated brazing material layer, Cu is not essential as the core material, but if it is less than 0.05% by mass, the effect of improving the strength and corrosion resistance after brazing is small. Moreover, if the difference with Cu density | concentration of a brazing material layer is less than 0.1 mass%, the effect which improves corrosion resistance is small. Therefore, the preferable Cu content in the core material is 0.05 to 1.0% by mass and less than or equal to the Cu concentration of the brazing material layer, and more preferably, the Cu concentration of the brazing material layer is −0.1% by mass or less. .

  In addition to the above, 0.3% by mass or less of Cr, Ni, Zr, etc. may be added for the purpose of increasing the potential of the core material and improving the strength. Moreover, you may add Zn: 1.0 mass% or less for electric potential gradient adjustment. As a result of Zn diffusion during brazing, the sacrificial anode layer side of the core material has a lower potential than the brazing material layer side, so that the region serving as the sacrificial anode material is expanded, and the anticorrosion effect is maintained longer. In addition, as an inevitable impurity, Fe, Sn, P, Be, B or the like may be contained in an amount of 0.3% by mass or less.

[Sacrificial anode layer]
The sacrificial anode layer contains Si: 0.03 to 1.5% by mass, Mn: 1.8% by mass or less, Zn: 2.5 to 7.0% by mass, and the balance is made of Al and inevitable impurities. . In addition, although the thickness of the sacrificial anode layer in the aluminum alloy brazing sheet for heat exchangers according to the present invention is not particularly limited, it is preferably 0.01 to 0.1 mm.

(Sacrificial anode layer Si: 0.03-1.5 mass%)
Si has the effect of improving the strength after brazing, and particularly when coexisting with Mg and Mn, the strength after brazing is further increased by the formation of Mg-Si intermetallic compounds and Al-Mn-Si intermetallic compounds. Can be increased. If it is less than 0.03% by mass, the effect is small. On the other hand, if it exceeds 1.5% by mass, the sacrificial anode layer is melted due to a decrease in the melting point of the sacrificial anode layer and an increase in the low melting point phase. Therefore, the content of Si in the sacrificial anode layer is 0.03 to 1.5% by mass, preferably 0.03 to 1.2% by mass.

(Sacrificial anode layer Mn: 1.8% by mass or less)
Mn has an effect of improving the strength after brazing, and the strength after brazing can be increased by increasing the content. Moreover, since it has the function of making the potential noble, the corrosion resistance is improved. On the other hand, if it exceeds 1.8% by mass, a coarse intermetallic compound is formed, which tends to cause a decrease in formability and corrosion resistance. Therefore, the content of Mn in the sacrificial anode layer is 1.8% by mass or less. Moreover, an effect is small if it is less than 0.03 mass%. Therefore, the preferable Mn content in the sacrificial anode layer is 0.03 to 1.8% by mass.

(Sacrificial anode layer Zn: 2.5-7.0 mass%)
Zn has a function of lowering the potential, and if it is less than 2.5% by mass, it is insufficient to act as a sacrificial anode. On the other hand, if it exceeds 7.0% by mass, the corrosion resistance of the brazing sheet single plate is good, but the Zn concentration in the fillet (brazing part) formed at the brazed joint increases, so the preferential corrosion of the fillet. There is a fear of happening. Moreover, since rolling cracks are generated, productivity is lowered. Therefore, the Zn content in the sacrificial anode layer is set to 2.5 to 7.0% by mass.

  In addition to the above, as having a low adverse effect on brazing, for example, to reduce the potential of the sacrificial anode layer and improve the strength after brazing, Fe is 0.5 mass% or less, In is 0.05 mass% or less, In order to reduce the potential of the sacrificial anode layer and to layer the corrosion form, 0.05% by mass or less of Sn may be added.

  Moreover, you may contain 0.1 mass% or less of Mg as an unavoidable impurity. In the present invention, Mg is not positively added to the sacrificial anode layer in order to emphasize brazing by the Nocolok brazing method. Mg has the effect of lowering the brazeability of the flux, and if it exceeds 0.1% by mass, the brazeability is significantly lowered. Therefore, Mg as an inevitable impurity in the sacrificial anode layer is limited to 0.1% by mass or less. Note that Mg combined with Si in the sacrificial anode layer is mainly diffused from the core material.

[Brazing material layer]
The brazing material layer is obtained by adding Cu of 3.0% by mass or less and Cu concentration or more of the core material to an Al—Si based alloy usually used in brazing an aluminum alloy. In addition, the thickness of the brazing filler metal layer in the aluminum alloy brazing sheet for heat exchanger according to the present invention is not particularly limited, but is preferably 0.01 to 0.1 mm.

(Braze material layer Si: 7.0 to 13.0% by mass)
Si has an effect of lowering the melting point and improving fluidity of the aluminum alloy brazing material. When the Si content is less than 7.0% by mass, the brazing amount is insufficient at the time of brazing, and the brazing property is lowered. On the other hand, if it exceeds 13.0% by mass, the formability deteriorates. Therefore, the content of Si in the brazing material layer is 7.0 to 13.0% by mass.

(Braze material layer Cu: 3.0% by mass or less and Cu concentration of core material or more)
Cu diffuses to the core material by hot rolling, softening annealing, and brazing during the manufacturing process of the brazing sheet, thereby forming a potential gradient that becomes noble from the outer side to the inner side in the core material. Improves corrosion resistance from If it is less than the Cu concentration of the core material, the potential near the center of the plate thickness becomes noble with respect to the inner side of the core material. On the other hand, if it exceeds 3.0% by mass, the potential difference between the fillet and its surroundings becomes large during fillet formation, and preferential corrosion may occur around the fillet. Therefore, the content of Cu in the brazing filler metal layer is set to 3.0% by mass or less and equal to or higher than the Cu concentration of the core material. The effect is small when the Cu content is less than 0.1% by mass or the difference from the Cu concentration of the core is less than 0.1% by mass. Therefore, the preferable Cu content in the brazing filler metal layer is 0.1 to 3.0% by mass and not less than the Cu concentration of the core material, more preferably not less than the Cu concentration of the core material + 0.1% by mass or more.

  In addition to the above, in order to make the potential noble on the brazing filler metal layer side (inside side) of the core material, 0.3% by mass or less of Cr, Ni, Zr or the like may be added. In addition, in the range where the potential gradient is not broken for potential adjustment (basement) when the brazing material layer forms a fillet (in the core material, the potential at the center of the plate thickness is not nobler than the potential on the brazing material layer side), Zn: You may add 1.0 mass% or less. By containing Zn in the fillet, the potential difference between the fillet and its periphery can be reduced, and preferential corrosion can be prevented.

  Moreover, in the aluminum alloy brazing sheet for a heat exchanger of the present invention, a layer made of a brazing material (sacrificial anode layer side brazing material layer) may be further laminated on the surface on the sacrificial anode layer side according to the application. Good.

[Sacrificial anode layer side brazing material layer]
In the present invention, the composition of the brazing filler metal layer on the sacrificial anode layer side is not particularly limited, and examples thereof include a 4000 series alloy which is an Al-Si series alloy. Moreover, in order to suppress Zn decrease of the sacrificial anode layer due to diffusion into the brazing material, an alloy obtained by adding Zn to a 4000 series alloy can be used. The preferable Zn content in the sacrificial anode layer side brazing filler metal layer is 1.0 to 3.0% by mass. The thickness of the brazing material layer on the sacrificial anode layer side in the aluminum alloy brazing sheet for heat exchanger according to the present invention is not particularly limited, and corresponds to brazing treatment, but is preferably 0.01 mm. That's it.

  The aluminum alloy brazing sheet for a heat exchanger according to the present invention is produced by a known clad material production method. One example will be described below.

  First, an aluminum alloy for the core material, an aluminum alloy for the sacrificial anode layer, an aluminum alloy for the brazing material layer, and if necessary, an aluminum alloy for the brazing material side brazing material layer are melted and cast by continuous casting. The core material ingot, the sacrificial anode layer ingot, the brazing material layer ingot, and the sacrificial anode layer side brazing material ingot are obtained by chamfering and homogenizing heat treatment. The ingot for the sacrificial anode layer, the ingot for the brazing material layer, and the ingot for the brazing material side brazing material layer are each made to have a predetermined thickness by hot rolling or cutting, and the sacrificial anode material, the brazing material, and the sacrificial anode A layer-side brazing material is obtained.

  Next, the core material ingot is sandwiched between the brazing material and the sacrificial anode material, and further, the sacrificial anode layer side brazing material is disposed on the outer side as necessary, and superposed so as to have a predetermined cladding ratio. After heating at a temperature of ℃ or higher, it is crimped by hot rolling to obtain a plate material. Thereafter, cold rolling, intermediate annealing, and cold rolling are performed to obtain a predetermined plate thickness. In addition, you may implement heat processing for the purpose of adjusting the element distribution in an alloy after cold bonding and before cold rolling. The intermediate annealing is desirably performed at 350 to 450 ° C. for 3 hours or more, and the final cold working rate is preferably 30 to 60%. In addition, after the final thickness is obtained, finish annealing may be performed in consideration of molding processability. Finish annealing can soften the material and improve the elongation, thereby ensuring workability.

  Although the best mode for carrying out the present invention has been described above, an example in which the effect of the present invention has been confirmed will be specifically described below in comparison with a comparative example that does not satisfy the requirements of the present invention. . In addition, this invention is not limited to this Example.

(Sample preparation)
A core material (C1 to C19), a sacrificial anode material (S1 to S13), and a brazing material (F1 to F12) having the compositions shown in Table 1, Table 2, and Table 3 were produced, and the combinations shown in Table 4 were superposed. The thickness of the sacrificial anode layer was clad with 10% of the entire plate thickness by cold rolling and the thickness of the brazing material layer was 10% of the total plate thickness, and the plate thickness was 0.3 mm by cold rolling. Thereafter, intermediate annealing is performed at 400 ° C. for 5 hours, and further cold rolling is performed to obtain a sheet thickness of 0.2 mm. Finally, finish annealing is performed at 300 ° C. for 3 hours, and the three-layer materials shown in Table 4 are obtained. Produced.

  Similarly, a sacrificial anode layer side brazing material (F12, F13) having the composition shown in Table 3 was manufactured, and the sacrificial anode layer side brazing material layer having a thickness of 10% of the total thickness of the combinations shown in Table 5 Then, the sacrificial anode layer having a thickness of 15% of the entire plate thickness, the core material, and the brazing material layer having a thickness of 10% of the entire plate thickness are laminated and clad, and the plate thickness is set to 0.3 mm by cold rolling. . Thereafter, intermediate annealing is performed at 400 ° C. for 5 hours, and further cold rolling is performed to obtain a sheet thickness of 0.2 mm. Finally, finish annealing is performed at 300 ° C. for 3 hours, and the four-layer materials shown in Table 5 are obtained. Produced.

Apply the commercially available non-corrosive flux of 5 g / m ² to the surface of the prepared three-layer material and four-layer material, hang it on a jig, and hold at 595 ° C. for 2 minutes in an atmosphere with an oxygen concentration of 200 ppm or less. As a result, brazing heating was performed to produce a brazing heat treatment material. Then, the brazing heat treatment material was cut out to prepare a test material having a predetermined shape and size, and a strength measurement and a corrosion test were performed after brazing.
In addition, as shown in FIG. 2, a non-corrosive flux is applied to a 0.1 mm thick brazing material with a brazing material processed into a corrugated shape, and the sacrificial anode layer side of the three-layer material (brazing sheet) And brazing and joining by brazing and heating under the same conditions as described above. On the other hand, a four-layer material (brazing sheet) is formed by applying the non-corrosive flux to the surface of the sacrificial anode layer side brazing material layer and attaching a fin material (bare fin material) having a thickness of 0.1 mm. Brazing and joining was performed in the same manner as the material. Corrosion tests were conducted on these finned test materials. The bare fin material is made of an aluminum alloy containing Zn: 2% by mass, and the fin material with a brazing material is made of a brazing material made of an aluminum alloy containing Si: 10% by mass on both sides of the bare fin material. The clad material was laminated at 10% of the total.
In Tables 4 and 5, those that could not be produced in a plate shape due to problems such as moldability and melting point are indicated by “-” in the result column.

(Measure strength after brazing)
The strength after brazing was measured by cutting out a JIS No. 5 test material from the brazed heat-treated material, performing a tensile test, and measuring the tensile strength. The measurement results are shown in Tables 4 and 5. The acceptance criteria for the strength after brazing was that the tensile strength was 180 MPa or more.

(Corrosion test)
In the corrosion test, a 60 mm × 50 mm test material is cut out from the brazing heat treatment material, and the brazing material layer side surface and end surface so that the sacrificial anode layer (4 layer material is the sacrificial anode layer side brazing material layer) side becomes the test surface. Was sealed with a sealing tape, and a CASS test (JIS Z 2371) was conducted for 1000 hours. After the test, the maximum corrosion depth was measured, and the minimum remaining plate thickness (= plate thickness before test−maximum corrosion depth) was calculated. The results are shown in Table 4 and Table 5.
On the other hand, in order to evaluate the corrosion resistance when the brazing sheet is used as a heat exchanger, the sacrificial anode layer (four-layer material is the sacrificial anode layer side brazing material layer) is used for the test material with fins in the same manner as the brazing heat treatment material. The CASS test was conducted by sealing the brazing material layer side surface and the end surface so that the side, that is, the surface to which the fin material was joined became the test surface. After the test, it was visually confirmed whether or not corrosion occurred at the joint (fillet and its surroundings) with the fin material. About the test material which corrosion generate | occur | produced, the remarks column is provided in Table 4 and Table 5, and it shows that.
The acceptance criteria for corrosion resistance are that the minimum remaining thickness of the brazed heat-treated material exceeds 80 μm (about 40% of the 0.2 mm thickness), and that there is no corrosion at the joint of the finned test material with the fin material It was.

(Evaluation by core material composition)
In Examples 1 to 3, since the Si content in the core material is within the scope of the present invention, the strength after brazing is sufficiently high. On the other hand, in Comparative Example 25, since the Si content of the core material was insufficient, the strength after brazing was not sufficiently obtained. On the other hand, in Comparative Example 26, since the Si content of the core material was excessive, the core material melted during brazing and a good test material was not obtained.

  Examples 1, 4, and 5 have sufficiently high strength after brazing because the Mn content in the core material is within the scope of the present invention. On the other hand, in Comparative Example 27, the strength after brazing was not sufficiently obtained because the Mn content of the core material was insufficient. On the other hand, in Comparative Example 28, since the Mn content of the core material was excessive, the moldability decreased due to the formation of a coarse Mn compound, and a good test material was not obtained.

  Examples 1, 6, and 7 have sufficiently high strength after brazing because the Mg content in the core material is within the scope of the present invention. On the other hand, in Comparative Example 29, the Mg content of the core material was insufficient, so that the strength after brazing was not sufficiently obtained. On the other hand, Comparative Example 30 was not suitable as an aluminum alloy brazing sheet for a heat exchanger because the Mg content of the core material was excessive, so that the brazing property was lowered and the brazing joint with the fin material was insufficient.

  Examples 1 and 8 have sufficiently high corrosion resistance because the Ti content in the core material is within the range of the present invention. On the other hand, in Comparative Example 32, since the Ti content of the core material was insufficient, the layered effect of the corrosion form was insufficient and pitting corrosion progressed. On the other hand, in Comparative Example 33, since the Ti content of the core material was excessive, the formability decreased due to the formation of a coarse Ti compound, and a good test material was not obtained.

(Evaluation by sacrificial anode layer composition)
In Examples 1, 9, and 10, since the Si content in the sacrificial anode layer is within the scope of the present invention, the strength after brazing is sufficiently high. On the other hand, in Comparative Example 34, the sacrificial anode layer lacks the Si content, so that the strength after brazing was not sufficiently obtained. On the other hand, in Comparative Example 35, since the Si content of the sacrificial anode layer was excessive, the sacrificial anode layer melted during brazing, and a good test material was not obtained.

  In Examples 1 and 11 to 13, since the Mn content in the sacrificial anode layer is within the range of the present invention, the strength after brazing is sufficiently high. On the other hand, in Comparative Example 36, since the Mn content of the sacrificial anode layer was excessive, the formability was lowered due to the formation of a coarse Mn compound, and a good test material was not obtained.

  Examples 1, 14, and 15 have a sufficiently high sacrificial anticorrosion effect because the Zn content in the sacrificial anode layer is within the scope of the present invention. On the other hand, since the Zn content of the sacrificial anode layer was insufficient in Comparative Example 37, the sacrificial anticorrosive effect was not sufficient, and the corrosion resistance was lowered. On the other hand, in Comparative Example 38, the corrosion resistance of the single plate was high because the Zn content in the sacrificial anode layer was excessive, but preferential corrosion occurred due to the Zn concentration increasing in the fillet.

(Evaluation by brazing material layer composition)
In Examples 1, 16, and 17, since the Si content in the brazing material layer is within the scope of the present invention, sufficient brazing properties can be secured. On the other hand, in Comparative Example 39, the brazing material layer lacks the Si content, so the brazing flow rate is insufficient and the brazing performance is lowered, and the brazing joint with the fin material is insufficient. It was. On the other hand, in Comparative Example 40, since the Si content of the brazing filler metal layer was excessive, the moldability of the brazing filler metal was deteriorated to cause rolling cracks, and no test material was obtained.

(Evaluation by Cu content of core material and brazing material layer)
In Examples 1 and 18 to 23, the Cu content in each of the core material and the brazing material layer is within the range of the present invention, so that the strength and corrosion resistance after brazing are sufficiently high. On the other hand, in Comparative Example 31, since the Cu content of the core material was excessive, burning occurred and a good test material could not be obtained. In Comparative Example 42, since the Cu content of the brazing material layer was excessive, the potential difference between the fillet of the test material with fins and the periphery thereof was large, and preferential corrosion occurred in the periphery of the fillet of the test material and the fin material. . On the other hand, in Comparative Example 41, since both the core material and the brazing material layer were free of Cu, the potential gradient was insufficient and the corrosion resistance was reduced. In Comparative Example 43, since the Cu content of the core material exceeds the Cu content of the brazing material layer, the potential gradient becomes noble near the center of the thickness of the test material, that is, in the center of the thickness of the core material (FIG. 3B). The sacrificial anticorrosive effect deeper than the center of the core plate thickness was not obtained, and a hole was formed in the test material in the corrosion test (minimum remaining plate thickness 0 μm).

(Evaluation of 4-layer material)
In Examples 44 and 45, since the brazing material was further laminated on the surface of the sacrificial anode layer / core material / brazing material layer side of the sacrificial anode layer whose composition was within the scope of the present invention, the strength after brazing and Corrosion resistance is high enough. In particular, in Example 45, Zn was added to the sacrificial anode layer-side brazing filler metal layer, so that the diffusion of the Zn in the sacrificial anode layer to the brazing filler metal layer and the reduction thereof were suppressed. Is big.

It is a figure which shows Cu, Zn density | concentration distribution and electric potential gradient in the aluminum alloy brazing sheet for heat exchangers which concerns on this invention, (a) is a Cu, Zn density | concentration distribution figure, (b) is an electric potential gradient figure. It is a schematic diagram of the test material with a fin which joined the fin material to the brazing sheet. It is a figure which shows the density | concentration distribution and potential gradient of Cu and Zn in the conventional aluminum alloy brazing sheet for heat exchangers, (a) is a density distribution figure of Cu and Zn, (b) is a potential gradient figure.

Claims (3)

An aluminum alloy brazing sheet for a heat exchanger, comprising: a core material; a sacrificial anode layer disposed on one surface side of the core material; and a brazing material layer made of an Al—Si based alloy disposed on the other surface side of the core material. And
The core is composed of Si: 0.3 to 1.5% by mass, Mn: 0.5 to 1.8% by mass, Mg: 0.05 to 0.5% by mass, Ti: 0.05 to 0.35% by mass. %, The balance consisting of Al and inevitable impurities,
The sacrificial anode layer contains Si: 0.03 to 1.5% by mass, Mn: 1.8% by mass or less, Zn: 2.5 to 7.0% by mass, and the balance is made of Al and inevitable impurities. Become
The brazing filler metal layer contains Si: 7.0 to 13.0% by mass, Cu: 3.0% by mass or less and Cu concentration or more of the core material, and the balance is made of Al and inevitable impurities. Aluminum alloy brazing sheet for heat exchanger.   The aluminum alloy brazing sheet for a heat exchanger according to claim 1, wherein the core material further contains Cu of 1.0 mass% or less and Cu content or less of the brazing material layer. An aluminum alloy brazing sheet for a heat exchanger, further comprising a layer made of a brazing material on the surface of the sacrificial anode layer side of the aluminum alloy brazing sheet for a heat exchanger according to claim 1 or 2.

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