JP2008188616A - Aluminum alloy-brazing sheet for heat exchanger having excellent brazability and corrosion resistance, and heat exchanger tube having excellent corrosion resistance - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an aluminum alloy-brazing sheet for a heat exchanger tube in which brazability and corrosion resistance at the internal face of a tube when being made into a heat exchanger tube are made consistent. <P>SOLUTION: Regarding the aluminum alloy brazing sheet for a heat exchanger tube, in an aluminum alloy core material 2, the face so as to be the external side of the tube is coated with a first aluminum alloy brazing filler metal 3 composed of an Al-Si based hypoeutectic alloy comprising, by mass, 5 to 12% Si, and the face so as to be the internal side of the tube is coated with a second aluminum alloy brazing filler metal 4 comprising, by mass, 2.1 to 5.0% Si, 0.2 to 7.0% Zn, 0.05 to 0.75% Mn, and the balance Al with inevitable impurities. The brazing sheet exhibits satisfactory brazability by the second aluminum alloy brazing filler metal so as to be the surface layer of the internal face of the tube, and further exhibits satisfactory corrosion resistance since suitable eutectic phases are almost uniformly present in the facial direction. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an aluminum alloy brazing sheet for a heat exchanger tube used for manufacturing a heat exchanger tube by brazing, and a heat exchanger tube excellent in corrosion resistance using the brazing sheet.

Aluminum heat exchangers are widely used as heat exchangers for automobile radiators, car heaters, oil coolers, intercoolers, car air conditioners, condensers, hydraulic equipment and industrial machinery.
For example, a pipe used in a conventional automotive heat exchanger uses a brazing sheet in which a JIS3003 alloy is used as a core material and an Al-Si brazing material is clad on one side and a sacrificial anode skin material such as JIS7072 is clad on the other side. Manufactured. In the production, the brazing sheet is bent into a tubular shape so that the inner surface becomes a sacrificial material, and a tube (hereinafter referred to as an electric sewing tube) is formed by high-frequency welding, and this electric sewing tube is combined with a fin, a header plate, etc. Fins and pipes are joined or pipes and header plates are joined.

As described above, a heat exchanger that uses a brazing sheet and is brazed with a fluoride-based flux or the like is widely known, and is mainly used in the field of automotive heat exchangers. As described above, the electric sewing tube forms a path through which the refrigerant flows before brazing, but in recent years, a method of forming a tube by brazing has been performed (for example, Patent Document 1, (Refer to 2. Hereinafter, a tube formed by brazing is referred to as a brazed tube.)
With the recent reduction in weight of automobiles, heat exchangers for automobiles are also being reduced in weight, and pipe materials are required to be thin and have high strength. When the plate thickness is 0.25 mmt or less, it becomes extremely difficult to form a tube between conventional electric sewings, so brazed tubes are becoming mainstream in thin tube materials.

The method of manufacturing the brazed tube is shown below.
-It is formed in a tubular shape so that the outer brazing material mainly for brazing with the fin material and the sacrificial material are brought into contact with each other.
· Brazing is performed in combination with the molded tube and fins or header plate.
-The brazing fluid is caused to flow by brazing, and the core material and the sacrificial material are joined via the brazing to form a tube.
JP-A-9-122804 JP 2002-267380 A

However, brazing pipes are excellent in terms of pipe forming, but if they are made thinner, the absolute amount of brazing material decreases, so brazing performance is partially reduced. In addition to reduced pressure strength and repeated fatigue life, problems such as crevice corrosion have occurred.
When the thickness of the brazing material is as thick as about 0.3 mm, the brazing material was generally about 10%. However, when the brazing sheet is thinned, the absolute amount of the brazing material is insufficient at the same cladding rate. Therefore, the cladding rate of the brazing material must be increased. If the clad rate of the brazing material is too thick in the thin-walled material, it is difficult to achieve both material strength and brazing properties, for example, the thickness of the core material becomes thin and the material strength cannot be secured.

On the other hand, these problems can be solved if a brazing material such as JIS 4343 alloy (Al-7.5% Si) or JIS 4045 alloy (Al-10% Si) is clad on both sides. However, particularly when the cooling water is in an acidic environment, if a brazing material having a large amount of Si is used on the inner surface, there is a problem that the corrosion rate becomes too fast.
Moreover, the antifreezing liquid which has ethylene glycol as a main component marketed as a coolant is added to cooling water by the density | concentration of 50 volume% at the maximum, and weak alkalinity-alkaline cooling water is used. In such an environment, even when a sacrificial material such as JIS7072 alloy is clad, there is a problem that a through-hole is formed at an early stage. Although a technology (Patent No. 3763498) has been developed to generate a noble compound from the matrix of the sacrificial material to ensure corrosion resistance in an alkaline environment, the corrosion resistance in an acidic environment is significantly reduced. There are problems such as.

  The present invention has been made against the background of the above circumstances, and it is possible to secure a good brazing property even in brazing of the inner surface of the pipe, and to exhibit excellent corrosion resistance in both acidic and alkaline environments on the inner surface of the pipe. An object of the present invention is to provide an aluminum alloy brazing sheet for heat exchanger tubes excellent in adhesion and corrosion resistance and a heat exchanger tube excellent in corrosion resistance.

  That is, among the aluminum alloy brazing sheets for heat exchanger tubes excellent in brazing and corrosion resistance of the present invention, the invention according to claim 1 is a mass% on the surface on the tube outer surface side of the aluminum alloy core material, The first aluminum alloy brazing material made of an Al—Si hypoeutectic alloy containing Si: 5 to 12% is coated, and the surface on the tube inner surface side is Si: 2.1 to 5. 0%, Zn: 0.2 to 7.0%, Mn: 0.05 to 0.75%, the balance being covered with the second aluminum alloy brazing material consisting of Al and inevitable impurities Features.

  The invention of the aluminum alloy brazing sheet for heat exchanger tubes excellent in brazeability and corrosion resistance according to claim 2 is the invention according to claim 1, wherein the core material is in mass% and Mn: 0.8-2. It contains 0%, Cu: 0.05 to 2.0%, Fe: 0.2 to 1.0%, and the balance is made of Al and inevitable impurities.

  The invention of the aluminum alloy brazing sheet for heat exchanger tubes excellent in brazing property and corrosion resistance according to claim 3 is the invention according to claim 2, wherein the core material further comprises, in mass%, Si: 0.3-1 .2%, Mg: 0.05 to 0.5% of one or two kinds are contained.

  The invention of the aluminum alloy brazing sheet for heat exchanger tubes excellent in brazing property and corrosion resistance according to claim 4 is the invention according to claim 2 or 3, wherein the core material further comprises, in mass%, Zr: 0.00. Contains one or more of 02 to 0.20%, Ti: 0.01 to 0.20%, Cr: 0.001 to 0.20%, V: 0.001 to 0.20% It is characterized by that.

  The invention of the aluminum alloy brazing sheet for heat exchanger tubes excellent in brazeability and corrosion resistance according to claim 5 is the invention according to any one of claims 1 to 4, wherein the first aluminum alloy brazing material has a mass of %, Si: 5 to 12%, with the balance being made of Al and inevitable impurities.

  The invention of the aluminum alloy brazing sheet for heat exchanger tubes excellent in brazing property and corrosion resistance according to claim 6 is the invention according to claim 5, wherein the first aluminum alloy brazing material further contains Zn: It is characterized by containing one or more of 0.5 to 5%, Sn: 0.001 to 0.20%, and In: 0.001 to 0.02%.

  The invention of the aluminum alloy brazing sheet for heat exchanger tubes excellent in brazing property and corrosion resistance according to claim 7 is the invention according to any one of claims 1 to 6, further comprising the second aluminum alloy brazing material. It is characterized by containing one or more of Fe: 0.2-1.0%, Ni: 0.1-0.7%, Ti: 0.01-0.50% by mass%. And

  The invention of the heat exchanger tube according to claim 8 is constituted by the brazed body of the aluminum alloy brazing sheet for heat exchanger tube according to any one of claims 1 to 7, and the eutectic phase in the surface direction of the tube inner surface. The ratio is 1 to 40% in terms of area ratio.

That is, according to the aluminum alloy brazing sheet for heat exchanger tubes excellent in brazing and corrosion resistance of the present invention, in the second brazing material that is the surface layer of the inner surface of the tube, it exhibits good brazing properties and in the surface direction. Appropriate eutectic phase is present almost evenly and exhibits good corrosion resistance.
That is, by adding Si and Zn to the second brazing material surface, not only the brazing property for tube formation is improved, but also the sacrificial anode effect due to the potential drop due to Zn can be ensured. Further, this eutectic phase can obtain good characteristics even in an alkaline environment. In an alkaline environment, a film mainly composed of aluminum hydroxide caused by corrosion is deposited on the surface of the material, but if this film is not uniform, corrosion proceeds locally, and through holes are likely to occur early. . Although there is a technique (Japanese Patent No. 3763498) for uniformly generating pitting corrosion as a technique for preventing this, corrosion does not proceed locally in this method, but the corrosion rate is fast, and when the thickness is reduced, the whole Will be lost due to corrosion. When there is a eutectic phase, a film formed in an alkaline environment can be adhered to the material, and the progress of corrosion can be significantly reduced. Although the vicinity of the eutectic is once dissolved by corrosion, the unevenness of this part serves as an anchor effect and the film adheres, so that the film on the material surface can be adhered.

  Moreover, according to the heat exchanger tube excellent in corrosion resistance of the present invention, an appropriate eutectic phase is formed on the inner surface of the tube as described above, and excellent corrosion resistance is exhibited in an alkaline environment and an acid environment.

  Below, the reason for limitation of the component in this invention is demonstrated. In addition, all content shown below is represented by the mass%.

(Second aluminum alloy brazing material composition)
Si: 2.1-5.0%
Si in the second aluminum alloy brazing material melts and flows to perform a brazing function such as formation of a refrigerant path. At this time, the core material is joined, or another member (internal fin or the like) is joined. Moreover, a eutectic phase is formed by brazing, and the corrosion resistance in an alkaline environment is improved. For this reason, Si is contained 2.1% or more. On the other hand, if the content exceeds 5.0%, erosion of the core material or the member to be joined becomes severe. Therefore, the Si content is set within the above range. For the same reason, it is desirable to set the lower limit to 2.5% and the upper limit to 4.0%.

Zn: 0.2-7.0%
Zn lowers the melting point of the second aluminum alloy brazing material and improves the brazing property. In addition, the potential is made lower, a potential distribution effective from the surface of the brazing material to the core material is formed, and the corrosion resistance in an acidic environment is improved. In order to obtain these effects, the content is 0.2% or more. On the other hand, if the content exceeds 7.0%, the self-corrosion rate becomes too fast. Therefore, the Zn content is set within the above range. For the same reason, it is desirable to set the lower limit to 1.0% and the upper limit to 5.0%.

Mn: 0.05 to 0.75%
Mn increases the viscosity of the molten brazing material, thereby suppressing the flow of the brazing material and making the eutectic phase on the tube surface after brazing uniform. If it is less than 0.05%, the wax flows too much, the surface eutectic phase is biased in the plane direction, and the corrosion resistance is lowered. On the other hand, when it contains exceeding 0.75%, the fluidity | liquidity of a wax will fall significantly and will inhibit the formation of a fillet. Therefore, the Mn content is set within the above range. For the same reason, it is desirable to set the lower limit to 0.5% and the upper limit to 0.7%.

Fe: 0.2-1.0%
Al and an intermetallic compound are produced, and the finely distributed intermetallic compound serves as a base point for the eutectic phase generation of the brazing filler metal. Fe forms an Al—Si—Fe-based compound and has a function of reducing the liquid phase rate by reducing the solid solubility of Si and suppressing the flow of wax. However, Fe can reduce the liquid phase wax, but cannot change the viscosity of the wax. In other words, in this case, Fe merely reduces the absolute amount of the melted wax, and does not provide the function of uniformly distributing the eutectic phase by reducing the viscosity of the wax. is not. However, Fe tends to be a starting point for melting the brazing material, and when added simultaneously with Mn, there is an effect of making the distribution of the eutectic phase more uniform. In order to obtain these effects sufficiently, when Fe is contained as desired, the content is set to 0.2% or more. On the other hand, when it contains exceeding 1.0%, rolling property and corrosion resistance will be reduced. Therefore, the Fe content to be contained as desired is determined within the above range. For the same reason, it is desirable to set the lower limit to 0.4% and the upper limit to 0.8%.

Ni: 0.1 to 0.7%
Ti: 0.01 to 0.50%
Ni and Ti produce an intermetallic compound with Al, and the finely distributed intermetallic compound serves as a starting point for the generation of the brazing filler metal eutectic phase. In order to sufficiently obtain the above action, Ni is contained in an amount of 0.1% or more and Ti is contained in an amount of 0.01% or more. However, if it is excessively contained, the rollability and corrosion resistance are lowered, so the above range is determined with Ni as the upper limit and 0.7% as the upper limit. For the same reason, it is desirable that the lower limit of Ni is 0.2%, the upper limit is 0.6%, the lower limit of Ti is 0.05%, and the upper limit is 0.20%.

(Suitable composition of core material)
An aluminum alloy is used for the core material constituting the aluminum alloy brazing sheet for heat exchanger tubes of the present invention. In the present invention, the composition of the core material is not limited to a specific one, but a composition suitable as the core material is shown below.

Mn: 0.8 to 2.0%
Mn crystallizes or precipitates as an intermetallic compound, and improves the strength after brazing. In addition, an Al—Mn—Si compound can be formed to lower the Si solid solubility of the matrix and improve the melting point of the matrix. In order to obtain these effects sufficiently, 0.8% or more is contained. On the other hand, when it contains excessively, castability and workability (rollability) will fall. Therefore, the above range is desirable for the Mn content. For the same reason, it is more desirable to set the lower limit to 1.0% and the upper limit to 1.6%.

Cu: 0.05-2.0%
Cu is dissolved in the matrix to improve the strength. In order to obtain this effect sufficiently, the content is 0.05% or more. On the other hand, if contained excessively, the corrosion rate becomes too fast. In addition, the melting point is lowered and it melts during brazing. Therefore, the above range is desirable for the Cu content. For the same reason, it is more desirable to set the lower limit to 0.1% and the upper limit to 0.7%.

Fe: 0.2-1.0%
Fe crystallizes or precipitates as an intermetallic compound, and improves the strength after brazing. In addition, Al—Mn—Fe, Al—Fe—Si, and Al—Mn—Fe—Si based compounds can be formed to lower the solid solubility of Mn and Si in the matrix and increase the melting point of the matrix. In order to obtain these effects sufficiently, it is necessary to contain 0.2% or more. On the other hand, if the content exceeds 1.0%, the corrosion rate becomes too fast, and the appearance of the giant crystallized product deteriorates the castability and rollability. Therefore, the content of Fe is preferably within the above range. For the same reason, it is more desirable to set the lower limit to 0.4% and the upper limit to 0.8%.

Si: 0.3-1.2%
Si in the core material is dispersed as an Al-Mn-Si compound or dissolved in a matrix to improve the strength, so that it is contained as desired. In order to obtain this effect sufficiently, the content is 0.3% or more. On the other hand, when it contains excessively, melting | fusing point will fall and it will fuse | melt at the time of brazing. Therefore, the content of Si is preferably in the above range. For the same reason, it is more desirable to set the lower limit to 0.5% and the upper limit to 1.0%.

Mg: 0.05-0.5%
Mg is dissolved in the matrix to improve the strength, so it is contained as desired. In order to obtain this effect sufficiently, the content is 0.05% or more. On the other hand, since the brazing property will be inhibited if contained excessively, the above range is desirable. For the same reason, it is more desirable to set the lower limit to 0.1% and the upper limit to 0.2%.

Zr: 0.02 to 0.20%
Ti: 0.01-0.20%
V: 0.001 to 0.20%
Cr: 0.001 to 0.20%
Zr, Ti, V, or Cr is dispersed as a fine intermetallic compound after brazing and improves strength, so that one or more kinds are optionally contained. In order to obtain the respective effects sufficiently, the content is 0.02% or more for Zr, 0.01% or more for Ti, 0.001% or more for V, and 0.001% or more for Cr. On the other hand, when it contains excessively, self-corrosion resistance will fall and workability will fall. Therefore, the upper limit of each is set to 0.20%. For the same reason, the lower limit of Zr is 0.05%, the upper limit is 0.1%, the lower limit of Ti is 0.05%, the upper limit is 0.20%, the lower limit of V is 0.01%, and the upper limit. More desirably, the lower limit of Cr is 0.1%, the lower limit of Cr is 0.01%, and the upper limit is 0.1%.

(Preferable composition of the first aluminum alloy brazing material)
An Al—Si hypoeutectic alloy is used for the first aluminum alloy brazing material constituting the aluminum alloy brazing sheet for heat exchanger tubes of the present invention. A composition suitable as the brazing material is shown below.

Si: 5 to 12%
Si melts and flows and contributes to bonding with the fin material and the like. Further, it is brazed with the second brazing material to form a refrigerant path. However, if it is less than 5%, the fluidity is lowered and it is difficult to obtain these effects sufficiently. On the other hand, when it exceeds 12%, the erosion to the core material or the member to be joined becomes severe. Therefore, the Si content is set within the above range.

Zn: 0.5-5%
Zn forms a potential distribution effective from the surface of the brazing material to the core material to prevent corrosion and improves the pitting corrosion resistance. In order to obtain this effect sufficiently, 0.5% or more is contained. On the other hand, if it exceeds 5%, the self-corrosion rate becomes too fast. Therefore, the Zn content is set within the above range.

Sn: 0.001 to 0.20%
In: 0.001 to 0.02%
Sn and In lower the potential and improve the sacrificial anode effect of the brazing material. Therefore, one or more Sn and In are contained as desired. In order to obtain this effect sufficiently, each content must be 0.001% or more. On the other hand, if the Sn content exceeds 0.20% and the In content exceeds 0.02%, the cost increases and further effects cannot be expected. Therefore, the respective contents are determined within the above ranges.

Eutectic phase area ratio on the tube inner surface: 1-40%
The presence of the eutectic phase on the inner surface of the tube can improve the corrosion resistance in an alkaline environment. In order to obtain the effect, the presence of 1% or more is necessary. On the other hand, when it exceeds 40%, the corrosion resistance in an acidic environment will fall. For the same reason, it is desirable that the lower limit is 5% and the upper limit is 30%.

  As described above, in the present invention of the aluminum alloy brazing sheet for heat exchanger tubes excellent in brazing and corrosion resistance, Si: 5 to 12 in mass% on the surface of the aluminum alloy core material on the tube outer surface side. Is coated with a first aluminum alloy brazing material made of an Al—Si hypoeutectic alloy, and the surface on the tube inner surface side is in mass%, Si: 2.1-5.0%, Zn: It contains 0.2 to 7.0%, Mn: 0.05 to 0.75%, and the remainder is coated with the second aluminum alloy brazing material made of Al and inevitable impurities, so it is good even on the inner surface of the pipe It exhibits brazing properties and further has an effect of exhibiting excellent corrosion resistance even in an alkaline environment and an acid environment.

  Further, in the present invention of a heat exchanger tube excellent in corrosion resistance, it is constituted by the aluminum alloy brazing sheet for a heat exchanger tube of the present invention, and the ratio of the eutectic phase in the surface direction of the tube inner surface is 1 to 40% in terms of area ratio. Therefore, the eutectic phase has an effect of exhibiting excellent corrosion resistance in both an alkaline environment and an acid environment.

Hereinafter, an embodiment of the present invention will be described.
An aluminum alloy for a core material, a first alloy for aluminum alloy brazing material, and a second alloy for aluminum alloy brazing material that are within the composition range of the present invention are prepared. These alloys can be melted by a conventional method. These alloys are subjected to semi-continuous casting, hot rolling, or alloy casting through continuous casting and rolling. These alloy plates are usually overlapped with each other and clad with an appropriate clad rate. The cladding is generally performed by rolling. Thereafter, further cold rolling is performed to obtain an aluminum alloy brazing sheet having a desired thickness. In addition, in the said manufacturing process, appropriate heat processings, such as intermediate annealing, can be interposed. For example, in order to optimize cold rolling properties and mechanical properties before being formed into a tube material, annealing may be performed at 300 to 400 ° C. for 1 to 4 hours at an intermediate or final plate thickness. However, in this annealing, if it exceeds 5 hours, Si in the brazing material diffuses into the core material, so that no eutectic phase is formed on the brazing material surface after brazing. For the same reason, the eutectic phase is not formed under brazing conditions in which the brazing material heat treatment is also maintained at a temperature higher than 600 ° C. for 15 minutes or more.

  As shown in FIG. 1A, the obtained aluminum alloy brazing sheet 1 has a first aluminum alloy brazing material 3 clad on one surface of a core material 2 and a second aluminum alloy on the other surface of the core material 2. The brazing material 4 is clad. This aluminum alloy brazing sheet 1 is formed into a tubular shape by being bent so that the second aluminum alloy brazing material 4 becomes the inner surface of the tube. In the form shown in FIG. 1, as shown in FIG. 1 (b), the refrigerant paths 5 and 5 are formed so that both end sides of the aluminum alloy brazing sheet 1 are in close contact with the central portion of the inner surface. Further, the first aluminum alloy brazing material 3 located on the outer surface side of the pipe is subjected to brazing heating by bringing a fin or the like (not shown) into close contact therewith. The heating conditions, atmosphere, and flux type in brazing are not particularly limited as the present invention.

  At the time of the brazing, the second aluminum alloy brazing material 4 has the brazing flow moderately suppressed, and the inner surface of the tube and the end of the aluminum alloy brazing sheet 1 are joined together. As shown in c), moderate fillets 6 and 6 are formed by the second aluminum alloy brazing material, and the brazed tube 10 is obtained. As a result of brazing, an eutectic phase with an area ratio of 1 to 40% was formed on the inner surface of the tube, and the flow of the brazing was moderately suppressed. A crystal phase is formed. Further, a fin (not shown) or the like is brazed to the outer surface of the brazing tube 10 to obtain a heat exchanger tube (brazing tube) 10.

An embodiment of the present invention will be described below.
Under normal conditions, the core alloy, the first aluminum alloy brazing alloy, and the second aluminum alloy brazing alloy having the compositions shown in Tables 1 to 3 (the balance being Al and inevitable impurities) were melted and cast. . Subsequently, chamfering and homogenization are performed, and the aluminum alloy for the core material is 160 mm, the first aluminum alloy brazing alloy and the second aluminum alloy brazing alloy are 20 mm by hot rolling and cold rolling, respectively. did. According to the combinations shown in Table 4, the clad is hot rolled, followed by cold rolling so that various final cold rolling rates are obtained while appropriately performing intermediate annealing, and a clad having a thickness of 0.20 mm is obtained. A material was prepared. The clad rate was 80% for the core material, 10% for the first aluminum alloy brazing material, and 10% for the second aluminum alloy brazing material.

  A tube having a cross-sectional shape as shown in FIG. This tube, fins, and header plate are combined, NOCOLOCK FLUX is applied, dried, and then subjected to brazing heat treatment in a high-purity nitrogen gas atmosphere at 605 ° C. for 3 minutes to provide a radiator core having 32 tubes (radiator size: Tube width 16mm Core size: 320mm length x 350mm width) was produced.

[Brassability]
Furthermore, as the heat treatment for the brazing of the radiator core, a heat treatment at 600 ° C. × 3 minutes was performed, and the brazing property was evaluated from the fracture pressure of the obtained radiator core. Decreases). The results are shown in Table 4.

  Moreover, in order to evaluate the uniformity of the eutectic phase ratio on the surface of the second aluminum alloy brazing material of the test material, in the vicinity of the fillet of the heat exchanger tube and in a part sufficiently separated from the fillet (distance 4 mm) The ratio of the eutectic phase was measured by subjecting a 1000 times SEM observation photograph to image analysis processing, and the difference in the ratio was evaluated. The results are shown in Table 4.

[Corrosion resistance in acidic environment]
The tube material was subjected to heat treatment simulating brazing at 605 ° C. for 3 minutes in a high-purity nitrogen gas atmosphere, and the tube material was cut into a length of 80 mm and a width of 40 mm to obtain a test material for a corrosion test. The maximum hole after the test was conducted by adding a corrosion resistance of 100 days to 40 ° C tap water adjusted to pH 3 with acetic acid and adding 100 ppm of Cu ²⁺ ions to the second aluminum alloy brazing filler metal side of the test material. The depth of meal was measured. The results are shown in Table 4.

[Corrosion resistance in alkaline environment]
The tube material was subjected to heat treatment simulating brazing at 605 ° C. for 3 minutes in a high-purity nitrogen gas atmosphere, and the tube material was cut into a length of 80 mm and a width of 40 mm to obtain a test material for a corrosion test. A corrosion test was performed on the second aluminum alloy brazing filler metal side of this test material by adding a commercially available coolant to a concentration of 30 vol% and immersing it in an 80 ° C. aqueous solution adjusted to pH 11 with NaOH for 60 days. It was. The maximum erosion depth after the test was measured. The results are shown in Table 4.

As shown in Table 4, the test material of the present invention is excellent in brazeability and also in the uniformity of the eutectic phase on the inner surface of the tube, and exhibits excellent corrosion resistance in both acidic and alkaline environments. It was. On the other hand, the comparative materials were inferior in corrosion resistance, and some of the comparative materials were also inferior in pressure resistance.
Comparative material No. No. 26 cracked during rolling and could not be used.

It is a figure which shows the manufacture flow of the aluminum alloy brazing sheet for heat exchanger tubes of one Embodiment of this invention, and a heat exchanger tube using the same.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Aluminum alloy brazing sheet 2 Core material 3 1st aluminum alloy brazing material 4 2nd aluminum alloy brazing material 10 Heat exchanger pipe

Claims (8)

A surface of the aluminum alloy core material on the outer surface side of the tube is coated with a first aluminum alloy brazing material made of an Al—Si hypoeutectic alloy containing 5% to 12% by mass of Si, and the inner surface of the tube On the surface to be the side, Si: 2.1-5.0%, Zn: 0.2-7.0%, Mn: 0.05-0.75% in mass%, with the balance being Al An aluminum alloy brazing sheet for heat exchanger tubes, which is coated with a second aluminum alloy brazing material made of inevitable impurities and is excellent in brazing and corrosion resistance. The core material contains, by mass%, Mn: 0.8 to 2.0%, Cu: 0.05 to 2.0%, Fe: 0.2 to 1.0%, and the balance is inevitable with Al. The aluminum alloy brazing sheet for heat exchanger tubes having excellent brazeability and corrosion resistance according to claim 1, comprising impurities. 3. The core material according to claim 2, further comprising one or two of Si: 0.3 to 1.2% and Mg: 0.05 to 0.5% by mass%. Aluminum alloy brazing sheet for heat exchanger tubes with excellent brazing and corrosion resistance. Further, the core material in terms of mass%, Zr: 0.02 to 0.20%, Ti: 0.01 to 0.20%, Cr: 0.001 to 0.20%, V: 0.001 to 0 The aluminum alloy brazing sheet for heat exchanger tubes having excellent brazeability and corrosion resistance according to claim 2 or 3, characterized by containing one or more of 20%. The brazing material according to any one of claims 1 to 4, wherein the first aluminum alloy brazing material contains, in mass%, Si: 5 to 12%, and the balance is made of Al and inevitable impurities. Alloy brazing sheet for heat exchanger tubes with excellent heat resistance and corrosion resistance. In addition to the first aluminum alloy brazing material, one of Zn: 0.5 to 5%, Sn: 0.001 to 0.20%, In: 0.001 to 0.02% or The aluminum alloy brazing sheet for heat exchanger tubes having excellent brazeability and corrosion resistance according to claim 5, comprising two or more kinds. In addition to the second aluminum alloy brazing material, Fe: 0.2 to 1.0%, Ni: 0.1 to 0.7%, Ti: 0.01 to 0.50%, 1% by mass. The aluminum alloy brazing sheet for heat exchanger tubes excellent in brazeability and corrosion resistance according to any one of claims 1 to 6, comprising seeds or two or more.   It is comprised by the brazing body of the aluminum alloy brazing sheet for heat exchanger pipes in any one of Claims 1-7, and the ratio of the eutectic phase in the surface direction of a pipe inner surface is 1 to 40% by an area rate. A heat exchanger tube characterized by.

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