JP2006002212A - Aluminum alloy extrusion tube for heat exchanger and heat exchanger - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an aluminum alloy extrusion tube composed of an alloy having extrusion property at the time of forming even in the case the thickness of an extruding material with a hollow shape is thin, also having sufficient material strength and further having excellent local corrosion resistance in a low concentration zinc-diffused layer. <P>SOLUTION: The aluminum alloy extrusion tube 1 for a heat exchanger is characterized in that the outer surface of an Al alloy extrusion material having a composition comprising, by mass, 0.5 to 1.0% Si, 0.5 to 1.4% Mn and 0.1 to 0.25% Ti, and the balance Al with inevitable impurities is provided with a Zn or Zn-containing layer. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

The present invention relates to an aluminum alloy extruded tube for a heat exchanger and a heat exchanger used as a structural member of a heat exchanger such as a condenser and an evaporator of a car air conditioner. _The present invention relates to an aluminum alloy extruded tube for a heat exchanger and a heat exchanger that can use ₂ as a refrigerant.

  Since Al and Al alloys are lightweight, have good thermal conductivity and excellent corrosion resistance, tubes made of extruded aluminum alloys (hereinafter referred to as aluminum (Al) alloy extruded tubes) are used as automotive air conditioners. It is widely used in heat exchangers such as.

For example, as shown in FIG. 2, the heat exchanger includes a pair of left and right tubes called header pipes 4 and a large number of aluminum alloys provided between the header pipes 4 so as to be spaced apart from each other in parallel. Tube 1 and fins 2 provided between the tube 1 and the tube 1.
The tubes 1 and the fins 2 are brazed, and the internal space of each tube 1 and the internal space of the header pipe 4 communicate with each other, and the medium is connected to the internal space of the header pipe 4 and the internal space of each tube 1. Is circulated so that heat can be exchanged efficiently through the fins 2.

  As each tube 1 constituting this heat exchanger, an extruded material having a flat cross section having a plurality of refrigerant passage holes 3 as shown in the perspective view of FIG. 1 is used, and this extruded material is formed by extrusion processing. Therefore, in general, a pure aluminum (Al) -based alloy typified by JIS1050 alloy having excellent extrudability is used.

  In order to further reduce the weight of such products, it is desired that the extruded material having a hollow shape (tubular shape) be thinner. However, as the thickness decreases, a tube having a predetermined shape and dimension is obtained. However, there is a problem that the extrudability is lowered and the mass productivity is impaired because it is necessary to reduce the extrusion speed at the time of molding. This decrease in extrudability was particularly noticeable when the thickness of the thinnest part formed on the outer surface of the extruded material was 0.30 mm or less.

  By the way, in the heat exchanger, internal pressure is applied to the tube by the refrigerant that passes through the tube, and when the material strength of the tube, especially when the proof stress is low, the wall surface of the tube swells outward due to this pressure, and in extreme cases There is also a risk of rupture.

  On the other hand, when the tube is used in a corrosive environment, local corrosion such as pitting corrosion may occur. However, when thinning is attempted, a through-hole may be formed relatively early and may not be able to withstand use. there were.

  Conventionally, to solve such corrosion resistance problems, a method has been used in which zinc (Zn) is coated on the tube surface and diffused into the tube by heating during brazing of the product. When it is relatively thick, a method of minimizing the progress of local corrosion by the so-called sacrificial anode effect of Zn has been used.

  Usually, such a Zn coating layer is disclosed by a method of forming a flat and tubular extruded material by spraying a Zn or Zn-containing layer on its outer surface (for example, patent document). 1).

  The thermal spraying is performed from above and below the outer flat portion of the extruded material so that the Zn coating layer is formed with a uniform film thickness on the outer flat portion of the extruded material. Then, since both ends of the upper and lower outer flat portions forming the extruded material have a certain curvature, the thickness of the Zn coating layer formed in the vicinity of both ends becomes thinner than the outer flat portions and becomes non-uniform. There was a trend. In such a part, it becomes a low concentration zinc diffusion layer.

  The reduction in thickness and non-uniformity of the Zn coating layer in the vicinity of both ends of the extruded material has been a concern from the viewpoint of causing a decrease in corrosion resistance. This is because when the thickness of the thinnest part formed on the outer surface of the extruded material becomes thinner than 0.30 mm, the material strength of the locally corroded portion is remarkably lowered in a conventional alloy (for example, 1050 or pure Al). If the strength is low, the deformation at the locally corroded portion proceeds due to the internal pressure of the heat exchange refrigerant, and there is a tendency to easily break.

In addition, a heat exchanger using carbon dioxide (CO ₂ ) as a refrigerant instead of a conventional chlorofluorocarbon refrigerant may be widely spread. When using CO ₂ as a refrigerant, it was necessary to further increase the high-temperature strength and pressure resistance of the tube. Specifically, when CO ₂ is used as a refrigerant, it needs a sufficient heat resistance even at a high temperature of 150 ° C., and requires a pressure strength 3 to 10 times that of a fluorocarbon refrigerant.

  From the background described above, in the extruded material constituting the aluminum alloy extruded tube, it has excellent extrudability even when the wall thickness is reduced, has sufficient high-temperature strength and pressure strength, and in addition, low concentration zinc The development of an alloy having excellent local corrosion resistance of the diffusion layer was expected.

Patent Document 2 discloses an extruded tube for a heat exchanger having Mn and Ti. However, as is clear from the examples, the extruded tube described in Patent Document 2 is mainly aimed at improving the corrosion resistance and not aiming at improving the strength.
Further, Patent Document 3 discloses an extrusion header tank for a heat exchanger having Mn and Ti. However, the contents described in this document are not related to the tube and are used for different purposes.
JP-A-9-137245 JP 2002-79370 A JP 2002-275565 A

  The present invention has been made in view of the above circumstances, and is excellent in extrudability at the time of molding even when the thickness of a hollow extruded material is thin, has sufficient material strength, and has a low concentration of zinc. An object of the present invention is to provide an aluminum alloy extruded tube made of an alloy excellent in local corrosion resistance of a diffusion layer and a heat exchanger using the tube.

In order to achieve the above object, the present invention employs the following configuration.
The aluminum alloy extruded tube for a heat exchanger of the present invention is 0.5% to 1.0% Si, 0.5% to 1.4% Mn, 0.1% to 0.00% by mass%. A feature of the present invention is that a Zn or Zn-containing layer is provided on the outer surface of an Al alloy extruded material containing 25% or less of Ti and the remainder comprising Al and inevitable impurities.

According to said structure, since Ti is contained in addition to Si and Mn, extrudability can be improved and the high temperature strength and room temperature strength of tube itself can be improved dramatically. Thereby, in addition to the fluorocarbon refrigerant, a CO ₂ refrigerant can be used.
Further, by adding Si, extrudability, pressure strength and local corrosion resistance can be improved. Furthermore, by adding Mn, the pressure strength and the high temperature strength can be increased at the same time.

The Zn or Zn-containing layer is formed by spraying Zn or a Zn-containing alloy or applying a Zn-containing flux. Examples of the Zn-containing flux include compounds such as ZnF ₂ , ZnCl ₂ , and KZnF ₃ .
By providing a Zn or Zn-containing layer on the outer surface of the tube, a Zn diffusion layer is formed on the tube surface after brazing, and this Zn diffusion layer functions as a sacrificial anode layer, thereby enhancing the anticorrosion effect of the tube. it can.

  Moreover, the aluminum alloy extruded tube for a heat exchanger of the present invention is the aluminum alloy extruded tube for a heat exchanger as described above, and is further 0.05% or more and 0.20% or less by mass% to the Al alloy extruded material. Cu is added.

  According to the said structure, pressure resistance strength can be raised more by adding Cu, without impairing extrudability and local corrosion resistance.

  Moreover, in the aluminum alloy extruded tube for heat exchangers of the present invention, the total amount of Mn and Ti is preferably more than 1.25% and not more than 1.65%. With this configuration, the pressure strength can be further increased.

  Moreover, in the aluminum alloy extruded tube for heat exchangers of the present invention, it is preferable that the thickness of the thinnest part formed on the outer surface of the Al alloy extruded material is 0.10 mm or more and 0.30 mm or less.

  In the present specification, the thinnest portion formed on the outer surface of the extruded material is formed between the refrigerant passage hole 3 and the outer surface of the tube 1, for example, in the case of the tube 1 constituting the heat exchanger as shown in FIG. In the thick part of the tube 1, it points the part where the thickness becomes the smallest. Although FIG. 1 shows an example in which the cross-sectional shape of the refrigerant passage hole 3 is a substantially square shape, it may be any shape such as a circle or an ellipse in addition to a square. Further, the number of refrigerant passage holes 3 to be installed and the interval at which the refrigerant passage holes 3 are provided are not limited to the example of FIG.

  Next, the heat exchanger of the present invention is manufactured using the aluminum alloy extruded tube for a heat exchanger described in any of the above. The above-described extruded tube can sufficiently maintain its function even if it is thinned compared to the conventional tube, and it is possible to provide a heat exchanger that can be significantly reduced in weight by mounting this.

According to the aluminum alloy extruded tube for a heat exchanger of the present invention, even when the extruded material having a hollow shape is thin, it has excellent extrudability at the time of molding, has sufficient material strength, and has a low concentration zinc diffusion layer. It is possible to improve the local corrosion resistance.
Further, even when the extruded material constituting the extruded tube is thin, the extruded tube is excellent in extrudability at the time of molding and has sufficient material strength. Therefore, the weight of the extruded tube can be further reduced.

In addition, since the extruded tube according to the present invention can maintain its function sufficiently even if it is made thinner than before, it is possible to provide a heat exchanger that can be further reduced in weight by installing this. It becomes.
In addition, since the pressure resistance and the high temperature strength are excellent, in addition to the chlorofluorocarbon refrigerant, a CO ₂ refrigerant can also be suitably used.

  Furthermore, a heat exchanger having the above-described effects contributes to an improvement in fuel efficiency of an automobile or the like equipped with the heat exchanger, and also contributes to an improvement in long-term reliability because durability during long-term use is also improved.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
The aluminum alloy extruded tube for a heat exchanger of the present invention is 0.5% to 1.0% Si, 0.5% to 1.4% Mn, 0.1% to 0.00% by mass%. A Zn or Zn-containing layer is provided on the outer surface of an Al alloy extruded material containing 25% or less of Ti and the remainder comprising Al and inevitable impurities. Moreover, 0.05% or more and 0.20% or less of Cu may be further added to the Al alloy extruded material by mass%.

The Zn or Zn-containing layer is formed by spraying Zn or a Zn-containing alloy or applying a Zn-containing flux. Examples of the Zn-containing flux include compounds such as ZnF ₂ , ZnCl ₂ , and KZnF ₃ . By providing a Zn or Zn-containing layer on the outer surface of the tube, a Zn diffusion layer is formed on the tube surface after brazing, and this Zn diffusion layer functions as a sacrificial anode layer to enhance the anticorrosion effect of the tube Can do.

Next, the reason for limiting the composition of the extruded aluminum alloy will be described.
(Si content)
By using Si as an alloy additive element, it is possible to enhance the extrudability, the room temperature strength of the material, and the local corrosion resistance of the low concentration zinc diffusion layer when the zinc coating amount is relatively small. That is, the Si element added to the Al alloy increases the strength from room temperature to 200 ° C. without substantially increasing the hot deformation resistance of the alloy, and sufficiently exhibits the sacrificial anode even with a relatively small amount of zinc. It is effective.

  In particular, in the extruded material constituting the aluminum alloy extruded tube, the corrosion resistance deteriorates in the portion where the thickness of the Zn coating layer is thin, that is, in the portion where the thickness of the Zn coating layer is reduced or non-uniformity occurs near both ends of the extruded material. As a means for suppressing the above, an Al—Si alloy according to the present invention (an Al alloy containing 0.5% to 1.0% by mass of Si, with the balance being Al and inevitable impurities) is excellent. .

  Therefore, according to the present invention, even when the thickness of the extruded material constituting the extruded tube is thin, it has excellent extrudability at the time of molding, has sufficient material strength, and local corrosion resistance of the low concentration zinc diffusion layer. An aluminum alloy extruded tube made of an excellent alloy can be obtained.

When the Si content is less than 0.5%, the corrosion resistance (maximum corrosion depth) and extrudability are excellent, but there is a tendency that the tensile strength from room temperature to 200 ° C. cannot be obtained sufficiently. On the other hand, when the Si content exceeds 1.0%, the tensile strength is improved, but the corrosion resistance and extrudability tend to be impaired, and the melting start temperature of the Al alloy is lowered, and the soldering temperature is about 600 ° C. During heating at the time of application, partial melting of the material may occur, and a normal heat exchanger cannot be manufactured.
Considering such points, the Si content of the extruded material is preferably 0.5% or more and 1.0% or less, and more preferably 0.6% or more and 0.8% or less.

(Mn content)
The alloy according to the present invention, that is, the Al—Si alloy, further increases Mt, so that not only room temperature strength but also high temperature strength is remarkably increased. If the Mn content is less than 0.5%, the effect of improving the strength at room temperature and high temperature is not sufficient, and if the content increases, the extrudability decreases, so the upper limit was made 1.4%.

(Ti content)
The alloy according to the present invention, that is, the Al—Si alloy, can increase the room temperature strength without impairing the extrudability and local corrosion resistance by containing Ti. In particular, the high temperature strength and pressure strength can be greatly improved. On the other hand, if the Ti content is less than 0.1%, the above effect is not sufficient, and if it exceeds 0.25%, the extrudability and the corrosion resistance are deteriorated.

(Total amount of Mn and Ti)
The total amount of Mn and Ti is preferably more than 1.25% and not more than 1.65% because the pressure strength can be further increased. More preferably, the range is 1.3% or more and 1.5% or less. If the total amount of Mn and Ti is 1.25% or less, the pressure strength is reduced, which is not preferable, and if it exceeds 1.65%, the extrusion characteristics are deteriorated.

(Cu content)
Moreover, the alloy which concerns on this invention, ie, an Al-Si type alloy, can raise room temperature intensity | strength, without impairing extrudability and local corrosion resistance by containing Cu further. On the other hand, if the Cu content is less than 0.05%, the above effect is not sufficient, and if it exceeds 0.20%, the extrudability and the corrosion resistance are deteriorated.

  In the aluminum alloy extruded tube for a heat exchanger of the present invention, the thickness of the thinnest part formed on the outer surface of the Al alloy extruded material is preferably 0.10 mm or more and 0.30 mm or less, and preferably 0.12 mm or more and 0 or less. More preferably, it is 25 mm or less.

In the case of a conventional thickness such that the thinnest portion formed on the outer surface of the extruded material exceeds 0.30 mm, for example, a thickness of about 0.4 mm, there is no particular problem in terms of characteristics even with the conventional Al (1050). However, when the thinnest part of the conventional material is 0.30 mm or less in thickness, problems arise in terms of extrudability and strength.
On the other hand, when the thinnest part formed on the outer surface of the extruded material has a thickness of 0.30 mm or less, the characteristics of the alloy according to the present invention, that is, the Al—Si alloy are sufficiently exhibited.
If the thickness of the thinnest part of the outer surface of the extruded material is less than 0.10 mm, even if this alloy is used, the corrosion resistance is remarkably reduced, and it is difficult to maintain sufficient characteristics from the point of extrudability and strength. I can't stand it. On the other hand, when the thinnest part formed on the outer surface of the extruded material exceeds 0.30 mm, it is not always necessary to use this alloy, and the product cannot be reduced in weight sufficiently. Absent.

In addition, by providing a Zn or Zn-containing layer on the outer surface of the tube, a Zn diffusion layer is formed on the surface of the tube after brazing. Can be increased. This Zn or Zn-containing layer is formed by spraying Zn or a Zn-containing alloy or applying a Zn-containing flux. Examples of the Zn-containing flux include compounds such as ZnF ₂ , ZnCl ₂ , and KZnF ₃ .

Hereinafter, the present invention will be described in more detail with reference to Examples.
(Experimental example 1)
First, Al alloys containing 0.8% by mass of Mn and 0.1% by mass of Ti and further changing the Si content in the range of 0.05% to 1.5% were respectively melted and cast. Billets with different compositions with a diameter of 200 mm were produced.
Next, for each billet having a different composition, the billet is homogenized under normal conditions, and the billet subjected to the homogenization is hot extruded at a temperature of 500 ° C. and an extrusion speed of 60 m / min. As shown in FIG. 1, a flat extruded material having 10 refrigerant passage holes and having a cross-sectional dimension of width: 20 mm, height: 2 mm, and wall thickness: 0.20 mm was formed.
Next, for each extruded material formed from billets having different compositions, a Zn coating layer made of industrial pure Zn was provided on the outer surface of the extruded material using a thermal spraying method before the temperature of the extruded material cooled. At that time, the weight of the Zn coating layer in the outer flat portion of the extruded material was about 10 g / m ² .
Furthermore, after performing extrusion and thermal spraying treatment for each billet having a different composition, an extruded tube as shown in FIG. 1 was produced by water cooling.

The maximum corrosion depth, extrudability, and tensile strength (room temperature strength) were examined for the extruded tube formed by the above procedure. The tube core joined to the fin by brazing was evaluated for corrosion resistance by SWAAT (abbreviation of See Water Acetic Acid Test, standard: ASTM G85-85) for 10 days.
The maximum corrosion depth of the extruded tube was determined by observing the local corrosion portion with an optical microscope and measuring the distance between the sample surface and the bottom surface of the corrosion portion.
The extrudability of the extruded tube was evaluated by the magnitude of the extrusion pressure when processed at a speed of 60 m / min.
The tensile strength of the extruded tube was evaluated by a value obtained by dividing the load when the extruded tube broke by the cross-sectional area of the sample after performing a heat treatment equivalent to brazing at 600 ° C. for 3 minutes.

  Table 1 shows the relationship between the Si content contained in the Al alloy extruded materials of Samples 1 to 8, and the corrosion resistance (maximum corrosion depth), extrudability (extrusion pressure), and tensile strength of the extruded tube.

  The extrusion pressure is expressed by defining the value of the extrusion pressure obtained with Sample 1 having a Si content of 0.05% as 1. That is, the extrusion pressures in Samples 2 to 8 are normalized by dividing by the value of the extrusion pressure obtained in Sample 1 having a Si content of 0.05%.

From Table 1, the following points became clear about the maximum corrosion depth.
(A1) The maximum corrosion depth shows an increasing tendency as the Si content increases.
(A2) If the Si content is more than 0.8%, the maximum corrosion depth exceeds 0.05 mm, and local corrosion starts to accelerate.
(A3) When the Si content exceeds 1.0%, the maximum corrosion depth further accelerates and exceeds 0.15 mm, and in particular, where the thickness of the Zn coating layer is reduced, local corrosion resistance can be maintained. Disappear.

From Table 1, the following points became clear about extrusion pressure.
(B1) The extrusion pressure increases monotonously as the Si content increases, but the increase is slight up to 1.00%.
(B2) When the Si content is more than 1.00%, the extrusion pressure increases rapidly, and when it is 1.50%, it becomes 2.00, which makes it difficult to form a thin extruded tube.

From Table 1, the following points became clear about the tensile strength.
(C1) The tensile strength is maximum when the Si content is 1.5%, and tends to gradually decrease when the Si content is reduced.

  From the above results, in order to have excellent properties at the same time in the evaluation of the maximum corrosion depth, extrudability and tensile strength, the Si content is in the range of 0.5% to 1.0% by mass%. I understand that it is necessary. Further, when the Si content is in the range of 0.6% to 0.8% by mass%, it is more preferable because further excellent corrosion resistance (maximum corrosion depth), extrudability and tensile strength can be obtained.

(Experimental example 2)
Next, the Si content is 0% or 0.7% by mass, Mn is 0% or 0.4 to 1.5%, Ti is 0% or 0.05 to 0.3%. , Al alloys in which Cu was changed in the range of 0% or 0.03 to 0.25% were melted and cast to produce billets having a diameter of 200 mm and different compositions.
Next, for each billet having a different composition, the billet is homogenized under normal conditions, and the billet subjected to the homogenization is hot extruded at a temperature of 500 ° C. and an extrusion speed of 60 m / min. As shown in FIG. 1, a flat extruded material having 10 refrigerant passage holes and having a cross-sectional dimension of width: 20 mm, height: 2 mm, and wall thickness: 0.20 mm was formed.
Next, a Zn coating layer was formed by spray-coating a Zn-containing flux composed of KZnF _{3 on} the outer surface of the extruded material formed from billets having different compositions. Also, some of the extruded material molded from billet, and the brazing material powder 5 parts by weight of the Al-Si alloy powder containing Si 10 wt%, and a Zn-containing flux 1 part by weight consisting of KZnF ₃ were mixed A flux mixture was sprayed onto the outer surface of the extruded material to form a Zn coating layer. In both cases, the weight of the Zn-containing flux in the outer flat portion of the extruded material was about 10 g / m ² .
Further, for each billet having a different composition, extrusion and thermal spraying were performed, and then water cooling was performed to produce extruded tubes of Sample 9 to Sample 27 as shown in FIG. Table 2 shows the alloy composition of each extruded material and the type of Zn coating layer.

The extruded tube formed by the above procedure was examined for high-temperature strength characteristics, tensile strength, maximum pitting corrosion depth and extrusion pressure. The tube core joined to the fin by brazing was evaluated for corrosion resistance by SWAAT for 10 days.
The high temperature strength characteristics of the extruded tube were determined by conducting a tensile test while the tube was heated to 150 ° C.
The tensile strength, maximum pitting corrosion depth and extrusion pressure of the extruded tube were determined in the same manner as in Experimental Example 1. The results are shown in Table 3. The extrusion pressure was based on the extrusion pressure of Sample 12.

  As shown in Table 3, Samples 9 to 18 and 23 and 24 show excellent values for all indicators of tensile strength at 150 ° C, tensile strength at room temperature, maximum pitting corrosion depth and extrusion pressure. I understand. In particular, it can be seen that the tensile strength at room temperature is greatly improved as compared with the samples 25 and 26 to which Ti is not added. It can also be seen that the tensile strength at 150 ° C. of Samples 9 to 18, 23, and 24 is significantly improved as compared with Samples 25 and 26 to which no Ti is added.

Next, for samples 19 to 22 and 25 to 27, since the addition amounts of Ti, Mn, and Cu are not appropriate, it can be seen that the indicators are generally lower than those of samples 9 to 18.
Further, when comparing the sample 12 and the sample 27, the difference between the two is whether or not the brazing material of the Zn coating layer was added, but in the sample 27 to which the brazing material was added, both of 150 ° C. and room temperature were obtained. It can be seen that the tensile strength is greatly reduced. It is considered that this is because Si in the brazing material combines with Mn contained in the extruded material to form a SiMn precipitate, and thereby the amount of Mn in the extruded material is insufficient and the strength is lowered.

  Furthermore, for samples 12, 13, 17, 18, and 24, the total amount of Mn and Ti is in the range of 1.25 to 1.65%, so that the tensile strength is higher than the other samples. I understand.

As described above, according to the extruded materials of Samples 9 to 18, 23, and 24, it is possible to ensure sufficient high-temperature strength and pressure resistance even when using not only conventional chlorofluorocarbon refrigerant but also CO ₂ refrigerant. it can. Among these, it can be seen that Samples 12, 13, 17, 18, and 24 have superior strength.

  Table 4 shows the thickness T of the extruded tube of the sample 12 obtained by the above procedure in a range of 0.05 mm to 0.40 mm, and summarizes the corrosion resistance (days). . The corrosion resistance of the extruded tube was evaluated by the number of days required for the tube to penetrate in the above-described SWAAT.

  From Table 4, it can be seen that the extruded tube has a corrosion resistance of 20 days or more when its thickness is 0.10 mm or more. Therefore, by making the thickness of the extruded tube in the range of 0.10 mm to 0.30 mm, it is possible to provide an extruded tube having excellent corrosion resistance.

  The technical scope of the present invention is not limited to the above embodiment, and various modifications can be made without departing from the spirit of the present invention. For example, an element that has been confirmed to have an effect of improving the corrosion resistance, that is, Fe or Zn may be contained within a range in which the above-described functions and effects are not impaired.

FIG. 1 is a perspective view showing an example of an extruded tube. FIG. 2 is a perspective view showing an example of a heat exchanger.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Tube (aluminum alloy extrusion tube for heat exchangers), 2 ... Fin, 3 ... Refrigerant passage hole, 4 ... Header pipe

Claims (5)

  It contains 0.5% to 1.0% Si, 0.5% to 1.4% Mn, and 0.1% to 0.25% Ti, and the rest An aluminum alloy extruded tube for a heat exchanger, characterized in that a Zn or Zn-containing layer is provided on the outer surface of an Al alloy extruded material comprising Al and inevitable impurities.   The aluminum alloy extruded tube for heat exchanger according to claim 1, wherein 0.05% or more and 0.20% or less of Cu is further added to the Al alloy extruded material by mass%.   The aluminum alloy extruded tube for a heat exchanger according to claim 1 or 2, wherein the total amount of Mn and Ti is more than 1.25% and not more than 1.65%.   4. The heat exchanger according to claim 1, wherein a thickness of the thinnest portion formed on the outer surface of the Al alloy extruded material is 0.10 mm or more and 0.30 mm or less. 5. Aluminum alloy extruded tube. A heat exchanger manufactured using the aluminum alloy extruded tube for a heat exchanger according to any one of claims 1 to 4.

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