JP6155156B2 - Aluminum alloy heat exchanger - Google Patents

Description

  The present invention relates to an aluminum alloy heat exchanger that is manufactured by brazing using a molded brazing sheet and has excellent corrosion resistance at a brazed joint.

  Al alloys are lightweight and have excellent thermal conductivity, high corrosion resistance can be realized by appropriate treatment, and efficient joining is possible by brazing using brazing sheets. It has been heavily used as an exchange material. In recent years, in order to improve the performance of automobiles or to cope with the environment, there has been a demand for improving the performance of heat exchangers so as to be lighter and more durable, and there is a demand for Al alloy material technology that can cope with this. As one form of such an aluminum alloy heat exchanger, an extruded flat tube and an external fin formed by corrugating a brazing sheet fin material are combined. Further, the brazing sheet is formed into a cylindrical shape at both ends of the tube. A heat exchanger is currently used which is inserted into a sewn header and joined by brazing.

  However, since the electric sewing header is manufactured in a separate process from the brazing, it causes a cost increase, and a heat exchanger structure capable of joining all members by one brazing has been desired. In response to this demand, a method for solving the problem by using two members as the header has been proposed. Patent Document 1 discloses a heat exchanger in which a tank and a header plate are joined to form a heat exchange refrigerant passage. However, in Patent Document 1, the two members of the header are joined by the Al—Si brazing filler metal part and the Al—Zn lining material, and further improvement has been expected with respect to prevention of corrosion of the joint part. .

  Further, a method for improving the corrosion resistance of the joint between the tube and the header is disclosed with respect to the problem of corrosion of the joint. Patent Document 2 discloses a method for manufacturing a heat exchanger in which the potential on the tube surface is relatively 20 mV or more relative to the joint fillet. However, although preferential corrosion can be suppressed by having a base portion than the joint fillet, the header is formed from one member, and when the header is made of two members, the priority of the joint portion between the header members is preferred. Since it is necessary to consider corrosion, Patent Document 2 cannot be applied.

JP 2009-275246 A JP 2009-139052 A

  The present invention has been made in view of the above circumstances, and is a heat exchanger that joins tubes, fins, header plates, and tank plates by a single brazing operation, and is particularly excellent in corrosion resistance of brazed joint portions. An object of the present invention is to provide an aluminum alloy heat exchanger.

  In order to solve the above-mentioned problems, the present inventors have examined in detail the influence of the combination of the configuration of the tube, fin, header plate, and tank plate on the corrosion resistance. As a result, at the junction between the tube and the header plate, the pitting corrosion potential at the junction is determined so that the pitting corrosion potential at the lowest pitting corrosion potential in the tube thickness direction and the pitting corrosion potential in the header plate thickness direction. In the junction between the header plate and the tank plate, the pitting corrosion potential at the junction is set to be the lowest in the thickness direction of the header plate. It has been found that the corrosion resistance of the brazed joint can be remarkably improved by making it nobler than both the pitting corrosion potential and the pitting corrosion potential of the portion having the lowest pitting corrosion potential in the thickness direction of the tank plate. Furthermore, it discovered that the lifetime as a heat exchanger could be improved significantly by making these balance. The present invention has been made based on these findings.

That is, in the aluminum alloy heat exchanger of the present invention, a plurality of tubes each having a flat shape and having a fluid passage inside are arranged in parallel, and corrugated fins are sandwiched between adjacent tubes and arranged and joined. A heat exchanger in which a header plate is integrated at both ends of the tube by brazing, and a tank plate is brazed and joined adjacent to the header plate to form a hollow medium passage inside. The pitting corrosion potential at the junction between the tube and the header plate is the lowest pitting corrosion potential in the thickness direction of the tube and the lowest pitting corrosion potential in the thickness direction of the header plate. The pitting corrosion potential at the junction between the header plate and the tank plate is higher than both of the pitting corrosion potentials of the header plate and the tank plate. The tube is more noble than both the pitting potential of the portion having the lowest pitting potential in the plate thickness direction and the pitting potential of the portion having the lowest pitting potential in the thickness direction of the tank plate. Si: 0.05 to 0.5 mass% (hereinafter referred to as “%”), Cu: 0.1 to 0.8%, Mn: 0.05 to 0.5%, the balance being Al and inevitable impurities It consists of Al alloy material which gave 3-15 g / m < ² > Zn to the surface of Al alloy.

  ADVANTAGE OF THE INVENTION According to this invention, the heat exchanger made from an aluminum alloy which is excellent in especially the corrosion resistance of a brazing junction part can be provided.

It is a figure which shows the structure of the aluminum-alloy heat exchanger which concerns on one Embodiment of this invention, (a) is a front view, (b) is an AA cross-section enlarged schematic diagram of (a). It is sectional drawing which shows the two-layer brazing sheet clad on one side used by this invention, (a) is a 1st 2 layer brazing sheet, (b) is an example of a 2nd 2 layer brazing sheet. It is sectional drawing which shows the 3 layer brazing sheet used by this invention, (a) is the 1st 3 layer brazing sheet which carried out double-side clad, (b) is the 2nd 3 layer brazing sheet which carried out double side clad, (c) is single side | surface. An example of a clad third three-layer brazing sheet. It is sectional drawing which shows the joining state with a tube, a header plate, and a tank plate, (a) is a 1st 2 layer brazing sheet, (b) is an example using the 2nd 2 layer brazing sheet as a header plate. It is sectional drawing which shows the joining state with a tube, a header plate, and a tank plate, (a) is a 2nd 2 layer brazing sheet, (b) is an example using the 1st 3 layer brazing sheet as a header plate. It is sectional drawing which shows the joining state with a tube, a header plate, and a tank plate, (a) is a 2nd 2 layer brazing sheet, (b) is an example using a 2nd 3 layer brazing sheet as a header plate. It is sectional drawing which shows the joining state with a tube, a header plate, and a tank plate, (a) is a 2nd 2 layer brazing sheet, (b) is an example using the 3rd 3 layer brazing sheet as a header plate. It is sectional drawing which shows the joining state with a tube, a header plate, and a tank plate, (a) is a 2nd 3 layer brazing sheet, (b) is an example using the 3rd 3 layer brazing sheet as a header plate.

  Hereinafter, an aluminum alloy heat exchanger according to an embodiment of the present invention will be described in detail.

[1. Heat exchanger structure]
1A and 1B show the structure of an aluminum alloy heat exchanger according to an embodiment of the present invention.
In the aluminum alloy heat exchanger 1, a plurality of tubes 2 having a flat shape and having fluid passages therein are arranged in parallel, and corrugated fins 3 are sandwiched and arranged between adjacent tubes 2 and joined. Header plates 4A and 4B are integrated with both ends of the tube 2 by brazing, and tank plates 5A and 5B are brazed and joined adjacent to the header plates 4A and 4B to form a hollow medium passage 6 inside. Is formed.

[2. Potential of heat exchanger]
In the aluminum alloy heat exchanger 1, as shown in FIG. 1 (b), the pitting corrosion potential (A1) of the joint 7 between the tube 2 and the header plate 4 is the pitting corrosion potential in the plate thickness direction of the tube 2. The pitting corrosion potential (B1) at the lowest part and the pitting corrosion potential (B2) at the lowest part in the thickness direction of the header plate 4 are more noble. Further, the pitting corrosion potential (A2) of the joint portion 8 between the header plate 4 and the tank plate 5 is the pitting corrosion potential (B2) at the lowest pitting corrosion potential in the thickness direction of the header plate 4 and the tank plate 5 It is more noble than both the pitting corrosion potential (B3) of the portion having the lowest pitting corrosion potential in the thickness direction. These relationships are shown in the following formula (1).
{(A1)> (B1) and (A1)> (B2)}, and
{(A2)> (B2) and (A2)> (B3)} (1)

  When parts having different pitting corrosion potentials are in contact with the same electrolyte, pitting corrosion of the part having the lowest pitting corrosion potential proceeds preferentially. This is called dissimilar metal contact corrosion, and sacrificial corrosion is a reverse use of this phenomenon. In order to prevent the preferential corrosion of the joint portion, it is necessary to arrange a portion having a pitting potential lower than that of the joint portion around the joint portion. It is desirable that the base portion is the outermost surface that can easily come into contact with the electrolyte. In a heat exchanger, if it penetrates even in one place, it will lead to a leak and will lose the function as a heat exchanger. For this reason, it is necessary to simultaneously improve the corrosion resistance of the joint 7 between the tube 2 and the header plate 4 and the joint 8 between the header plate 4 and the tank plate 5. Furthermore, in order to improve the corrosion resistance other than the joint, it is desirable that the tube 2, the header plate 4, and the tank plate 5 have a base layer having a pitting potential lower than that of the core material on the outer surface side. Moreover, it is desirable that the pitting corrosion potential of the fin 3 is lower than the pitting corrosion potential of the core material of the tube 2.

[3. Composition of Al alloy tube]
The Al alloy tube used in the present invention includes Si: 0.05 to 0.5 mass% (hereinafter referred to as%), Cu: 0.1 to 0.8%, and Mn: 0.05 to 0.5%. An Al alloy material containing 3 to 15 g / m ² of Zn is used on the surface of the Al alloy containing the remaining Al and inevitable impurities.

(Si: 0.05-0.5%)
Si of the Al alloy tube used in the present invention is contained in an amount of 0.05 to 0.5%. Si is an element that improves the strength after brazing by forming a solid solution in the matrix or forming an Al—Mn—Si intermetallic compound, and also makes the potential of the core material noble by solid solution Si. In order to obtain the effect of adding Si, it is necessary to contain 0.05% or more of Si. On the other hand, when Si is contained excessively exceeding 0.5%, the extrudability is lowered and the melting point of the alloy is lowered to cause melting of the material at the time of brazing. Si is related to solute Mn in order to form an Al—Mn—Si intermetallic compound. Specifically, the lower the Si concentration, the higher the solid solution Mn concentration, and the potential becomes noble. The amount of Si is more preferably 0.05 to 0.25%.

(Cu: 0.1-0.8%)
Cu of the Al alloy tube used in the present invention is contained in an amount of 0.1 to 0.8%. Cu is dissolved in the matrix to improve the strength, enhances the potential of the core material, and increases the potential difference from the surface to improve the sacrificial anticorrosive effect of the brazing material. When the Cu content is less than 0.1%, the effect is small. On the other hand, if it exceeds 0.8%, the melting point of the matrix is lowered, so that the material is easily melted during brazing. The Cu content is more preferably 0.3 to 0.6%.

(Mn: 0.05 to 0.5%)
Mn of the Al alloy tube used in the present invention is contained in an amount of 0.05 to 0.5%. Mn is an element that crystallizes or precipitates as an Al—Mn-based intermetallic compound, contributes to improvement in strength after brazing addition heat, and makes the potential of the core material noble by solute Mn. In order to obtain this effect, it is necessary to add 0.05% or more of Mn. However, if the amount of Mn exceeds 0.5%, the extrudability is lowered, and a huge intermetallic compound may be crystallized, which may impair the productivity. Therefore, the upper limit of the amount of Mn is 0.5%. And Further, Mn is related to solute Si in order to form an Al—Mn—Si intermetallic compound. Specifically, the lower the Mn concentration, the higher the solute Si concentration, and the potential becomes noble. The amount of Mn is more preferably 0.1 to 0.3%.

(Inevitable impurities)
Fe as an inevitable impurity of the Al alloy tube used in the present invention crystallizes or precipitates as an intermetallic compound, and increases the corrosion rate. The Fe content is preferably 0.4% or less.

Mg in the Al alloy tube used in the present invention may be contained in an amount of 0.05 to 0.5%. Mg contributes to strength improvement by fine precipitation as Mg ₂ Si. In order to obtain the effect of adding Mg, it is preferable to contain 0.05% or more of Mg. On the other hand, if Mg is contained excessively exceeding 0.5%, brazing properties may be impaired, or intergranular corrosion may occur, resulting in a decrease in corrosion resistance. The amount of Mg is more preferably 0.1 to 0.3%.

  Ti, Zr, Cr and V of the Al alloy tube used in the present invention may be contained in an amount of 0.05 to 0.3%. Ti, Zr, Cr and V contribute to the improvement of corrosion resistance, particularly pitting corrosion resistance. That is, Ti added to the Al alloy is divided into a high-concentration region and a low-concentration region, and these are alternately distributed in the thickness direction. Then, the region with low Ti, Zr, Cr, and V concentration corrodes preferentially over the region with high Ti concentration, so that the corrosion form becomes layered, and as a result, the progress of corrosion in the thickness direction is hindered. Pitting resistance is improved. If the amount of Ti, Zr, Cr and V is less than 0.05%, such an effect of improving pitting corrosion resistance cannot be obtained sufficiently. On the other hand, if the amount of addition of Ti, Zr, Cr and V exceeds 0.3%, a coarse compound may be generated during casting, which may impair manufacturability. The Ti, Zr, Cr, and V amounts are more preferably 0.1 to 0.2%.

(Zn content: 3 to 15 g / m ² )
Zn is given to the outer surface of the Al alloy tube used in the present invention. Examples of the Zn application method include Zn spraying, Zn coating, and plating. In Zn spraying, the Zn sprayed layer becomes a layer in which Zn is diffused by performing a brazing treatment. Since the Zn diffusion layer has a lower pitting corrosion potential than the portion of the Al alloy where Zn is not diffused, the sacrificial anticorrosion effect can prevent the Al alloy and improve the durable life of the Al alloy.

The amount of Zn applied is 3 to 15 g / m ² . When the amount of sprayed Zn is less than 3 g / m ² , the sacrificial anticorrosive effect is not sufficiently exhibited, corrosion that leads to early penetration occurs, or the pitting corrosion potential on the tube surface is pitting corrosion at the joint between the tube and the header plate. May become more noble than the potential. In addition, when the Zn application amount exceeds 15 g / m ² , the corrosion rate increases, the Zn diffusion layer is consumed quickly, or the pitting potential at the joint between the tube and the header plate becomes extremely low. End up. As for the provision amount of Zn, it is more preferable to set it as 5-10 g / m < ² >.

(Method of manufacturing an Al alloy tube)
About the manufacturing method of the tube made from Al alloy used for this invention, a normal method can be employ | adopted and it does not specifically limit, For example, it is preferable to do as follows. First, homogenization treatment and chamfering are performed on the ingot as necessary, and the billet is heated to 450 to 570 ° C. before extrusion to extrude the billet so that it has a predetermined outer diameter and thickness. A drawing process is performed, and a Zn addition process is further performed. In addition, in order to adjust the mechanical characteristics of the obtained clad extruded tube, heat treatment may be performed in a timely manner at any stage of the manufacturing process.

[4. Al alloy header plate and tank plate]
The Al alloy header plate and the tank plate are formed of a brazing sheet in which a core material and a brazing material are formed on the surface thereof. The brazing sheet is a two-layer brazing sheet or a three-layer brazing sheet depending on the type of brazing material formed on the outer side or inner side of the core material. Both of these can be used, but the composition of the core material is any of the brazing sheets. Is also common. Hereinafter, the composition of the core material will be described.

[4.1.1 Core Material Composition]
The core material (L0) of the Al alloy header plate and tank plate contains Si: 0.05 to 1.0%, Cu: 0.05 to 1.0%, and Mn: 0.5 to 2.0%. Further, it is made of an Al alloy composed of the balance Al and inevitable impurities.

(Si: 0.05-1.0%)
The core material (L0) of the header plate and tank plate contains 0.05 to 1.0% of Si. When Si in the core material coexists with Mn, it becomes an Al-Mn-Si-based compound phase and is dispersed or dissolved in the matrix to improve the strength, and the potential of the core material is made noble by the dissolved Si. . The effect is small when the Si content is less than 0.05%. If it exceeds 1.0%, the amount of precipitation of Al—Si-based or Al—Mn—Si-based compound inside the core material increases, and an excessive amount of compound may decrease the corrosion resistance. Si is related to solute Mn in order to form an Al—Mn—Si intermetallic compound. Specifically, the lower the Si concentration, the higher the solid solution Mn concentration, and the potential becomes noble.

(Mn: 0.5-2.0%)
The core material (L0) of the header plate and the tank plate contains 0.5 to 2.0% of Mn. Mn improves the sacrificial anticorrosion effect by dissolving in the matrix and increasing the pitting potential difference with the surface. Moreover, Mn crystallizes or precipitates as an Al-Mn type intermetallic compound, and improves the strength after brazing. Furthermore, an Al—Mn—Si compound is formed to lower the Si solid solubility in the matrix and improve the melting point of the matrix. If the Mn content is less than 0.5%, the effect is small, and if it exceeds 2.0%, a coarse Al—Mn-based compound phase is formed, so that the corrosion resistance and workability deteriorate. Further, Mn is related to solute Si in order to form an Al—Mn—Si intermetallic compound. Specifically, the lower the Mn concentration, the higher the solute Si concentration, and the potential becomes noble.

(Cu: 0.05-1.0%)
The core material (L0) of the header plate and the tank plate contains 0.05 to 1.0% of Cu. Cu is dissolved in the matrix to improve the strength, and also improves the sacrificial anticorrosive effect of the brazing material by making the potential of the core material noble and increasing the pitting potential difference from the surface. When the Cu content is less than 0.05%, the effect is small. On the other hand, if it exceeds 1.0%, the melting point of the matrix is lowered, so that the material is easily melted during brazing.

(Ti, Zr, Cr, V: 0.05 to 0.3%)
The core material (L0) of the header plate and the tank plate may contain 0.05 to 0.3% of Ti, Zr, Cr or V. These elements contribute to improvement of corrosion resistance, particularly pitting corrosion resistance. That is, Ti, Zr, Cr, or V added to the aluminum alloy is divided into a high concentration region and a low concentration region, and they are alternately distributed in the thickness direction. Then, the low concentration region corrodes preferentially over the high concentration region, so that the corrosion form becomes layered, and as a result, the progress of corrosion in the plate thickness direction is hindered, and the pitting corrosion resistance is improved. If the amount of Ti, Zr, Cr and V is less than 0.05%, such an effect of improving pitting corrosion resistance cannot be obtained sufficiently. On the other hand, if the amount of addition of Ti, Zr, Cr and V exceeds 0.3%, a coarse compound may be generated during casting, which may impair manufacturability.

  The core material (L0) of the header plate and the tank plate may contain 0.05 to 1.0% Fe. Fe crystallizes or precipitates as an intermetallic compound and improves the core material strength.

  The core material (L0) of the header plate and the tank plate may contain 0.05 to 1.0% Mg. Mg has the effect of improving the strength of the core material.

[4.1.2 First two-layer brazing sheet (FIG. 2 (a))]
As shown in FIG. 2 (a), an Al—Si alloy brazing material (L1) is applied to the header plate or tank plate on the outer surface side of the core material (L0) having the composition described in [4.1.1]. A first two-layer brazing sheet that is disposed and clad on one side can be used.

  L1 contains 3.0 to 12.0% of Si. Si lowers the melting point of the aluminum alloy and produces a liquid phase, thereby enabling brazing. If the Si content is less than 3.0%, the liquid phase required for brazing cannot be sufficiently obtained, and the brazing property does not function satisfactorily. On the other hand, when the Si content exceeds 12.0%, coarse Si crystallizes during casting and cracks occur.

  L1 may contain 0.05 to 0.3% of Ti, Zr, Cr, or V. These elements contribute to improvement of corrosion resistance, particularly pitting corrosion resistance. That is, Ti, Zr, Cr, or V added to the aluminum alloy is divided into a high concentration region and a low concentration region, and they are alternately distributed in the thickness direction. Then, the low concentration region corrodes preferentially over the high concentration region, so that the corrosion form becomes layered. As a result, the progress of the corrosion in the plate thickness direction is hindered, and the pitting corrosion resistance is improved. In order to sufficiently obtain such an effect of improving the pitting corrosion resistance, the content of Ti, Zr, Cr or V is preferably 0.05% or more. On the other hand, if the content of Ti, Zr, Cr, or V exceeds 0.3%, a coarse compound is produced during casting, which may impair manufacturability.

  L1 may contain 0.05% to 1.0% of Fe or Ni. In general, Fe or Ni contributes to improvement of corrosion resistance.

  Furthermore, 0.05 to 1.5% of Mn may be contained in L1. Mn is an element that crystallizes or precipitates as an Al—Mn intermetallic compound and contributes to the improvement of strength.

  Furthermore, L1 may contain 10 ppm to 500 ppm of Na or Sr. Na and Sr have a function of refining the crystallized product of the Al—Si based alloy, and suppress the action of inhibiting corrosion resistance due to the concentration of corrosion on the coarse Al—Si based alloy particles.

[4.1.3 Second two-layer brazing sheet (FIG. 2B)]
As shown in FIG. 2B, the header plate or the tank plate has an Al—Si—Zn alloy brazing material (L2) on the outer surface side of the core material (L0) having the composition described in [4.1.1]. ) Can be used and a second two-layer brazing sheet clad on one side can be used.

  L2 contains 3.0 to 12.0% of Si. Si lowers the melting point of the aluminum alloy and produces a liquid phase, thereby enabling brazing. If the Si content is less than 3.0%, the liquid phase required for brazing cannot be sufficiently obtained, and the brazing property does not function satisfactorily. On the other hand, when the Si content exceeds 12.0%, coarse Si crystallizes during casting and cracks occur.

  The Zn content of L2 is 0 to 3.0%. By adding Zn, the pitting corrosion potential on the header plate and the tank plate surface is lowered. This surface acts as a sacrificial anticorrosion layer and improves the life of the header plate and the tank plate. On the other hand, since the joining of the tube and the header plate and the joining of the header plate and the tank plate are performed by L2, these pitting corrosion potentials become lower as the Zn content increases. Since Zn tends to concentrate at the joint, if the Zn content exceeds 3.0%, Zn concentration occurs at the joint, and the pitting corrosion potential at the joint between the tube and the header plate and between the header plate and the tank plate. The pitting corrosion potential at the joint becomes the lowest among the surrounding members. In addition, when Zn is 0, it becomes the composition similar to L1.

  L2 may contain 0.05 to 0.3% of Ti, Zr, Cr, or V. These elements contribute to improvement of corrosion resistance, particularly pitting corrosion resistance. That is, Ti, Zr, Cr, or V added to the aluminum alloy is divided into a high concentration region and a low concentration region, and they are alternately distributed in the thickness direction. Then, the low concentration region corrodes preferentially over the high concentration region, so that the corrosion form becomes layered. As a result, the progress of the corrosion in the plate thickness direction is hindered, and the pitting corrosion resistance is improved. In order to sufficiently obtain such an effect of improving the pitting corrosion resistance, the content of Ti, Zr, Cr or V is preferably 0.05% or more. On the other hand, if the content of Ti, Zr, Cr, or V exceeds 0.3%, a coarse compound is produced during casting, which may impair manufacturability.

  Further, L2 may contain 0.05 to 1.0% of Fe or Ni. In general, Fe or Ni contributes to improvement of corrosion resistance.

  Furthermore, L2 may contain 0.05 to 1.5% of Mn. Mn is an element that crystallizes or precipitates as an Al—Mn intermetallic compound and contributes to the improvement of strength.

  Furthermore, L2 may contain 10 ppm to 500 ppm of Na or Sr. Na and Sr have a function of refining the crystallized product of the Al—Si based alloy, and suppress the action of inhibiting corrosion resistance due to the concentration of corrosion on the coarse Al—Si based alloy particles.

[4.1.4 First three-layer brazing sheet (FIG. 3A)]
In the header plate or the tank plate, as shown in FIG. 3 (a), it is described in [4.1.3] on the outer surface side of the core material (L0) having the composition described in [4.1.1]. Use a first three-layer brazing sheet in which an Al—Si—Zn-based alloy brazing material (L2) having a composition is disposed on the inner surface side of the core material and clad on both sides of the Al—Si—Cu-based alloy brazing material (L3). Can do.

  L3 contains 3.0 to 12.0% of Si. Si lowers the melting point of the aluminum alloy and produces a liquid phase, thereby enabling brazing. If the Si content is less than 3.0%, the liquid phase required for brazing cannot be sufficiently obtained, and the brazing property does not function satisfactorily. On the other hand, when the Si content exceeds 12.0%, coarse Si crystallizes during casting and cracks occur.

  The Cu content of L3 is set to 0 to 1.0%. The Al—Si—Cu-based alloy brazing material (L3) not containing Zn clad on the inner surface side of the core material flows into the joint portion between the tube and the header plate and the joint portion between the header plate and the tank plate. It functions to lower the concentration and to make the pitting potential noble. Furthermore, by adding Cu, it is possible to increase the Cu concentration at the joint and further increase the pitting potential. However, if the Cu concentration exceeds 1.0%, cracks occur during casting. Therefore, the Cu content is 0 to 1.0%. In addition, when Cu is 0, it becomes the composition similar to L1.

  Further, L3 may contain 0.05 to 0.3% of Ti, Zr, Cr, or V. These elements contribute to improvement of corrosion resistance, particularly pitting corrosion resistance. That is, Ti, Zr, Cr, or V added to the aluminum alloy is divided into a high concentration region and a low concentration region, and they are alternately distributed in the thickness direction. Then, the low concentration region corrodes preferentially over the high concentration region, so that the corrosion form becomes layered. As a result, the progress of the corrosion in the plate thickness direction is hindered, and the pitting corrosion resistance is improved. In order to sufficiently obtain such an effect of improving the pitting corrosion resistance, the content of Ti, Zr, Cr or V is preferably 0.05% or more. On the other hand, if the content of Ti, Zr, Cr, or V exceeds 0.3%, a coarse compound is produced during casting, which may impair manufacturability.

  L3 may contain 0.05 to 1.0% of Fe or Ni. In general, Fe or Ni contributes to improvement of corrosion resistance.

  Furthermore, L3 may contain 0.05 to 1.5% of Mn. Mn is an element that crystallizes or precipitates as an Al—Mn intermetallic compound and contributes to the improvement of strength.

  Furthermore, L3 may contain 10 ppm to 500 ppm of Na or Sr. Na and Sr have a function of refining the crystallized product of the Al—Si based alloy, and suppress the action of inhibiting corrosion resistance due to the concentration of corrosion on the coarse Al—Si based alloy particles.

[4.1.5 Second three-layer brazing sheet (FIG. 3B)]
As shown in FIG. 3B, the header plate or the tank plate has an Al—Zn alloy brazing material (L4) on the outer surface side of the core material (L0) having the composition described in [4.1.1]. Using a second three-layer brazing sheet in which an Al—Si—Cu-based alloy brazing material (L3) having the composition described in [4.1.4] is disposed on the inner surface side of the core material and clad on both sides. Can do.

  L4 contains 0 to 3.0% of Zn. Even if L4 is 0% Zn, the pitting potential is lower than that of the core material. This surface works as a sacrificial anticorrosive layer, and the surface becomes more base with Zn concentration, and the sacrificial anticorrosive effect is enhanced. However, when the Zn concentration exceeds 3.0%, the corrosion rate of L4 increases and the Zn diffusion layer is consumed early.

  L4 may contain 0.05 to 0.3% of Ti, Zr, Cr, or V. These elements contribute to improvement of corrosion resistance, particularly pitting corrosion resistance. That is, Ti, Zr, Cr, or V added to the aluminum alloy is divided into a high concentration region and a low concentration region, and they are alternately distributed in the thickness direction. Then, the low concentration region corrodes preferentially over the high concentration region, so that the corrosion form becomes layered. As a result, the progress of the corrosion in the plate thickness direction is hindered, and the pitting corrosion resistance is improved. In order to sufficiently obtain such an effect of improving the pitting corrosion resistance, the content of Ti, Zr, Cr or V is preferably 0.05% or more. On the other hand, if the content of Ti, Zr, Cr, or V exceeds 0.3%, a coarse compound is produced during casting, which may impair manufacturability.

  L4 may contain 0.05 to 0.5% of Si. Si is an element that improves the strength after brazing by forming a solid solution in a matrix or generating an Al—Mn—Si intermetallic compound.

  L4 may contain 0.05 to 1.0% of Fe or Ni. In general, Fe or Ni contributes to improvement of corrosion resistance.

  L4 may contain 0.05 to 1.5% of Mn. Mn is an element that crystallizes or precipitates as an Al—Mn intermetallic compound and contributes to the improvement of strength.

  L4 may contain 10 ppm to 500 ppm of Na or Sr. Na and Sr have a function of refining the crystallized product of the Al—Si based alloy, and suppress the action of inhibiting corrosion resistance due to the concentration of corrosion on the coarse Al—Si based alloy particles.

[4.1.6 Third three-layer brazing sheet (FIG. 3C)]
In the header plate or the tank plate, as shown in FIG. 3 (c), [4.1.2] is written on the outer surface side of the core material (L0) having the composition described in [4.1.1]. An Al—Si alloy brazing material (L1) having a composition and an Al—Zn alloy skin material (L4) having a composition described in [4.1.5] are arranged between L1 and L0. Thus, a third three-layer brazing sheet clad on one side can be used.

[4.1.7 Manufacturing method of brazing sheet]
As a manufacturing method of the brazing sheet made of Al alloy used for the header plate and the tank plate, a normal method can be adopted and is not particularly limited. For example, the following method is preferable. That is, a core material, a brazing material, and a skin material corresponding to the combination to be manufactured are cast, both surfaces of the ingot are face-cut, and the clad layer is overlaid. This is preheated at 400 to 550 ° C. for 1 to 10 hours, and the thickness is reduced to about 5 mm by hot rolling. Furthermore, cold rolling and final annealing at 300 to 450 ° C. for 1 to 10 hours are performed to obtain a brazing sheet having a thickness of about 1.6 mm.

[4.2 Joining of tube and header plate]
[4.2.1 Joining of tube and first two-layer brazing sheet (FIG. 4 (a))]
When the first two-layer brazing sheet (FIG. 2 (a)) is used as the header plate in joining the tube and the header plate, the joint between the tube 2 and the header plate 4 as shown in FIG. 4 (a). Is made of an Al—Si alloy brazing material (L1). At this time, in addition to the L1 component, Zn and Cu diffuse from the tube 2 and Cu diffuses from the core material of the header plate 4 to the joint portion 7 between the tube 2 and the header plate 4, and these affect the pitting corrosion potential. give. If the composition of the tube 2 and the composition of the first two-layer brazing sheet are within the range defined by the present invention, the pitting corrosion potential at the lowest pitting corrosion potential in the thickness direction of the tube 2 <the tube 2 and the header plate 4 and the pitting corrosion potential of the portion having the lowest pitting corrosion potential in the thickness direction of the header plate 4 <the pitting corrosion potential of the bonding portion 7 of the tube 2 and the header plate 4. Holds.

[4.2.2 Joining of tube and second two-layer brazing sheet (FIG. 5 (a))]
When the second two-layer brazing sheet (FIG. 2B) is used as the header plate in joining the tube and the header plate, as shown in FIG. 5A, the tube 2 and the header plate 4 are joined. Is made of an Al—Si—Zn alloy brazing material (L2). At this time, in addition to L2 components, particularly Zn, Zn and Cu diffuse from the tube 2 and Cu diffuses from the core material of the header plate 4 in the joint 7 between the tube 2 and the header plate 4, and these are pitting corrosion. Affects the potential. If the composition of the tube 2 and the composition of the second two-layer brazing sheet are within the range defined in the present invention, the pitting corrosion potential at the lowest pitting corrosion potential in the plate thickness direction of the tube 2 <the tube 2 and the header plate 4 and the pitting corrosion potential of the portion having the lowest pitting corrosion potential in the thickness direction of the header plate 4 <the pitting corrosion potential of the bonding portion 7 of the tube 2 and the header plate 4. Holds.

[4.2.3 Joining of tube and first three-layer brazing sheet (FIG. 5B)]
When the first three-layer brazing sheet (FIG. 3 (a)) is used as the header plate in joining the tube and the header plate, the joint between the tube 2 and the header plate 4 as shown in FIG. 5 (b). Is made of an Al—Si—Zn alloy brazing material (L2) and an Al—Si—Cu alloy brazing material (L3). At this time, in the joint portion 7 between the tube 2 and the header plate 4, in addition to the components of L 2, particularly Zn and L 3, particularly Cu, Zn and Cu from the tube 2, and Cu from the core of the header plate 4 Diffuse, and these affect the pitting potential. If the composition of the tube 2 and the composition of the first three-layer brazing sheet are within the range defined by the present invention, the pitting corrosion potential of the portion having the lowest pitting corrosion potential in the thickness direction of the tube 2 <the tube 2 and the header plate 4 and the pitting corrosion potential of the portion having the lowest pitting corrosion potential in the thickness direction of the header plate 4 <the pitting corrosion potential of the bonding portion 7 of the tube 2 and the header plate 4. Holds.

[4.2.4 Joining of tube and second three-layer brazing sheet (FIG. 6B)]
When the second three-layer brazing sheet (FIG. 3B) is used as the header plate in joining the tube and the header plate, the joint between the tube 2 and the header plate 4 as shown in FIG. 6B. Is made of an Al—Si—Cu alloy brazing material (L3) and an Al—Zn alloy brazing material (L4). At this time, in addition to L3 components, particularly Cu, Zn and Cu from the tube 2, Cu from the core material of the header plate 4, and Al—Zn alloy brazing material in the joint 7 of the tube 2 and the header plate 4 Zn diffuses from (L4) and these affect the pitting potential. If the composition of the tube 2 and the composition of the second three-layer brazing sheet are within the range defined by the present invention, the pitting corrosion potential at the lowest pitting corrosion potential in the plate thickness direction of the tube 2 <the tube 2 and the header plate 4 and the pitting corrosion potential of the portion having the lowest pitting corrosion potential in the thickness direction of the header plate 4 <the pitting corrosion potential of the bonding portion 7 of the tube 2 and the header plate 4. Holds.

[4.2.5 Joining of tube and third three-layer brazing sheet (FIG. 7B)]
When the third three-layer brazing sheet (FIG. 3 (c)) is used as the header plate in joining the tube and the header plate, the joint between the tube 2 and the header plate 4 as shown in FIG. 7 (b). Is made of an Al—Si alloy brazing material (L1). At this time, in addition to the component L1, the joint 7 between the tube 2 and the header plate 4 contains Zn and Cu from the tube, Cu from the core material of the header plate 4, and Zn from the skin material (L4) of the header plate. Diffuse, and these affect the pitting potential. If the composition of the tube 2 and the composition of the third three-layer brazing sheet are within the range defined in the present invention, the pitting corrosion potential of the portion having the lowest pitting corrosion potential in the thickness direction of the tube 2 <the tube 2 and the header plate 4 and the pitting corrosion potential of the portion having the lowest pitting corrosion potential in the thickness direction of the header plate 4 <the pitting corrosion potential of the bonding portion between the tube 2 and the header plate 4. It holds.

[4.3 Joining of header plate and tank plate]
[4.3.1 Joining of the first two-layer brazing sheet and the second two-layer brazing sheet (FIGS. 4A and 4B)]
In joining the header plate and the tank plate, as shown in FIG. 4A, the first two-layer brazing sheet (FIG. 2A) is used as the header plate 4 and the second two-layer brazing is used as the tank plate 5. When the sheet (FIG. 2B) is used, the Al—Si alloy brazing material (L1) outside the header plate 4 and the core material inside the tank plate 5 are brought into contact with each other and brazed and joined. At this time, in addition to the L1 component, Cu diffuses from the core material of the header plate 4 and Cu diffuses from the core material of the tank plate 5 to the joint portion 8 between the header plate 4 and the tank plate 5, and these are pitting potentials. To affect. If the composition of the first two-layer brazing sheet and the composition of the second two-layer brazing sheet are within the range defined by the present invention, the pitting corrosion potential at the lowest pitting corrosion potential in the thickness direction of the header plate 4 <Pitting corrosion potential at the joint 8 between the header plate 4 and the tank plate 5 and the pitting corrosion potential at the lowest pitting corrosion potential in the thickness direction of the tank plate 5 <Junction between the header plate 4 and the tank plate 5 The relationship of the pitting corrosion potential of the part 8 is established.

  In joining the header plate and the tank plate, as shown in FIG. 4B, the second two-layer brazing sheet (FIG. 2B) is used as the header plate 4, and the first two-layer brazing is used as the tank plate 5. When the sheet (FIG. 2A) is used, the core material inside the header plate 4 and the Al—Si alloy brazing material (L1) outside the tank plate 5 are brought into contact with each other and brazed. At this time, in addition to the L1 component, Cu diffuses from the core material of the header plate 4 and Cu diffuses from the core material of the tank plate 5 to the joint portion 8 between the header plate 4 and the tank plate 5, and these are pitting potentials. To affect. If the composition of the first two-layer brazing sheet and the composition of the second two-layer brazing sheet are within the range defined by the present invention, the pitting corrosion potential at the lowest pitting corrosion potential in the thickness direction of the header plate 4 <Pitting corrosion potential at the joint 8 between the header plate 4 and the tank plate 5 and the pitting corrosion potential at the lowest pitting corrosion potential in the thickness direction of the tank plate 5 <Junction between the header plate 4 and the tank plate 5 The relationship of the pitting corrosion potential of the part 8 is established.

[4.3.2 Joining of the second two-layer brazing sheet and the first three-layer brazing sheet (FIGS. 5A and 5B)]
In joining the header plate and the tank plate, as shown in FIG. 5A, the second two-layer brazing sheet (FIG. 2B) is used as the header plate 4 and the first three-layer brazing is used as the tank plate 5. When the sheet (FIG. 3A) is used, the Al—Si—Zn alloy brazing material (L2) outside the header plate 4 and the Al—Si—Cu alloy brazing material (L3) inside the tank plate 5 are used. ), And brazed. At this time, in the joint portion 8 between the header plate 4 and the tank plate 5, Cu from the core material of the header plate 4 is added from the core material of the tank plate 5 in addition to the components of L 2, particularly Zn and L 3, particularly Cu. Cu diffuses and these affect the pitting potential. If the composition of the second two-layer brazing sheet and the composition of the first three-layer brazing sheet are within the range defined by the present invention, the pitting corrosion potential at the lowest pitting corrosion potential in the thickness direction of the header plate 4 <Pitting corrosion potential at the joint 8 between the header plate 4 and the tank plate 5 and the pitting corrosion potential at the lowest pitting corrosion potential in the thickness direction of the tank plate 5 <Junction between the header plate 4 and the tank plate 5 The relationship of the pitting corrosion potential of the part 8 is established.

  In joining the header plate and the tank plate, as shown in FIG. 5B, the first three-layer brazing sheet (FIG. 3A) is used as the header plate 4 and the second two-layer brazing is used as the tank plate 5. When the sheet (FIG. 2B) is used, the Al—Si—Cu alloy brazing material (L3) inside the header plate 4 and the Al—Si—Zn alloy brazing material (L2) outside the tank plate 5 are used. ), And brazed. At this time, in the joint portion 8 between the header plate 4 and the tank plate 5, Cu from the core material of the header plate 4 is added from the core material of the tank plate 5 in addition to the components of L 2, particularly Zn and L 3, particularly Cu. Cu diffuses and these affect the pitting potential. If the composition of the second two-layer brazing sheet and the composition of the first three-layer brazing sheet are within the range defined by the present invention, the pitting corrosion potential at the lowest pitting corrosion potential in the thickness direction of the header plate 4 <Pitting corrosion potential at the joint 8 between the header plate 4 and the tank plate 5 and the pitting corrosion potential at the lowest pitting corrosion potential in the thickness direction of the tank plate 5 <Junction between the header plate 4 and the tank plate 5 The relationship of the pitting corrosion potential of the part is established.

[4.3.3 Joining of the second two-layer brazing sheet and the second three-layer brazing sheet (FIGS. 6A and 6B)]
In joining the header plate and the tank plate, as shown in FIG. 6A, the second two-layer brazing sheet (FIG. 2B) is used as the header plate 4 and the second three-layer brazing is used as the tank plate 5. When the sheet (FIG. 3B) is used, the Al—Si—Zn alloy brazing material (L2) outside the header plate 4 and the Al—Si—Cu alloy brazing material (L3) inside the tank plate 5 are used. ), And brazed. At this time, in the joint portion 8 between the header plate 4 and the tank plate 5, Cu from the core material of the header plate 4 is added from the core material of the tank plate 5 in addition to the components of L 2, particularly Zn and L 3, particularly Cu. Cu diffuses and these affect the pitting potential. If the composition of the second two-layer brazing sheet and the composition of the second three-layer brazing sheet are within the range defined by the present invention, the pitting corrosion potential of the portion having the lowest pitting corrosion potential in the thickness direction of the header plate 4 <Pitting corrosion potential at the joint 8 between the header plate 4 and the tank plate 5 and the pitting corrosion potential at the lowest pitting corrosion potential in the thickness direction of the tank plate 5 <Junction between the header plate 4 and the tank plate 5 The relationship of the pitting corrosion potential of the part 8 is established.

  In joining the header plate and the tank plate, as shown in FIG. 6B, the second three-layer brazing sheet (FIG. 3B) is used as the header plate 4 and the second two-layer brazing is used as the tank plate 5. When the sheet (FIG. 2B) is used, the Al—Si—Cu alloy brazing material (L3) inside the header plate 4 and the Al—Si—Zn alloy brazing material (L2) outside the tank plate 5 are used. ), And brazed. At this time, in the joint portion 8 between the header plate 4 and the tank plate 5, Cu from the core material of the header plate 4 is added from the core material of the tank plate 5 in addition to the components of L 2, particularly Zn and L 3, particularly Cu. Cu diffuses and these affect the pitting potential. If the composition of the second two-layer brazing sheet and the composition of the second three-layer brazing sheet are within the range defined by the present invention, the pitting corrosion potential of the portion having the lowest pitting corrosion potential in the thickness direction of the header plate 4 <Pitting corrosion potential at the joint 8 between the header plate 4 and the tank plate 5 and the pitting corrosion potential at the lowest pitting corrosion potential in the thickness direction of the tank plate 5 <Junction between the header plate 4 and the tank plate 5 The relationship of the pitting corrosion potential of the part 8 is established.

[4.3.4 Joining of the second two-layer brazing sheet and the third three-layer brazing sheet (FIGS. 7A and 7B)]
In joining the header plate and the tank plate, as shown in FIG. 7A, the second two-layer brazing sheet (FIG. 2B) is used as the header plate 4 and the third three-layer brazing is used as the tank plate 5. When the sheet (FIG. 3C) is used, the core material inside the header plate 4 and the Al—Si alloy brazing material (L1) outside the tank plate 5 are brought into contact with each other and brazed. At this time, in addition to L 1, Cu diffuses from the core material of the header plate 4 and Zn diffuses from the skin material (L 4) of the tank plate 5 to the joint portion 8 between the header plate 4 and the tank plate 5. Affects eating potential. If the composition of the second two-layer brazing sheet and the composition of the third three-layer brazing sheet are within the range defined by the present invention, the pitting corrosion potential of the portion having the lowest pitting corrosion potential in the thickness direction of the header plate 4 <Pitting corrosion potential at the joint 8 between the header plate 4 and the tank plate 5 and the pitting corrosion potential at the lowest pitting corrosion potential in the thickness direction of the tank plate 5 <Junction between the header plate 4 and the tank plate 5 The relationship of the pitting corrosion potential of the part 8 is established.

  In joining the header plate and the tank plate, as shown in FIG. 7B, a third three-layer brazing sheet (FIG. 3C) is used as the header plate 4, and a second two-layer brazing is used as the tank plate 5. When the sheet (FIG. 2B) is used, the Al—Si alloy brazing material (L1) outside the header plate 4 and the core material inside the tank plate 5 are brought into contact with each other and brazed and joined. At this time, in addition to L 1, Zn diffuses from the skin material (L 4) of the header plate 4 and Cu diffuses from the core material of the tank plate 5 in the joint 8 between the header plate 4 and the tank plate 5. Affects eating potential. If the composition of the second two-layer brazing sheet and the composition of the third three-layer brazing sheet are within the range defined by the present invention, the pitting corrosion potential of the portion having the lowest pitting corrosion potential in the thickness direction of the header plate 4 <Pitting corrosion potential at the joint 8 between the header plate 4 and the tank plate 5 and the pitting corrosion potential at the lowest pitting corrosion potential in the thickness direction of the tank plate 5 <Junction between the header plate 4 and the tank plate 5 The relationship of the pitting corrosion potential of the part 8 is established.

[4.3.5 Joining the second three-layer brazing sheet and the third three-layer brazing sheet (FIGS. 8A and 8B)]
In joining the header plate and the tank plate, as shown in FIG. 8A, the header plate 4 is a second three-layer brazing sheet (FIG. 3B), and the tank plate 5 is a third three-layer brazing. When the sheet (FIG. 3C) is used, an Al—Si—Cu alloy brazing material (L3) inside the header plate 4 and an Al—Si alloy brazing material (L1) outside the tank plate 5 are used. Contact and braze. At this time, in addition to the component of L1 and the component of L3, particularly Cu, Cu from the core material of the header plate 4 is added to the skin plate of the tank plate 5 (L4) at the joint 8 between the header plate 4 and the tank plate 5. ) From Zn diffuses, which affects the pitting potential. If the composition of the second three-layer brazing sheet and the composition of the third three-layer brazing sheet are within the range defined by the present invention, the pitting corrosion potential at the lowest pitting corrosion potential in the thickness direction of the header plate 4 <Pitting corrosion potential at the joint 8 between the header plate 4 and the tank plate 5 and the pitting corrosion potential at the lowest pitting corrosion potential in the thickness direction of the tank plate 5 <Junction between the header plate 4 and the tank plate 5 The relationship of the pitting corrosion potential of the part 8 is established.

  In joining the header plate and the tank plate, as shown in FIG. 8B, the third three-layer brazing sheet (FIG. 3C) is used as the header plate 4, and the second three-layer brazing is used as the tank plate 5. When the sheet (FIG. 3B) is used, an Al—Si alloy brazing material (L1) outside the header plate 4 and an Al—Si—Cu alloy brazing material (L3) inside the tank plate 5 are used. Contact and braze. At this time, in addition to the L1 component and L3 component, particularly Cu, Zn from the skin material (L4) of the header plate 4 is added to the joint portion 8 between the header plate 4 and the tank plate 5. Cu diffuses from the core, which affects the pitting potential. If the composition of the second three-layer brazing sheet and the composition of the third three-layer brazing sheet are within the range defined by the present invention, the pitting corrosion potential at the lowest pitting corrosion potential in the thickness direction of the header plate 4 <Pitting corrosion potential at the joint 8 between the header plate 4 and the tank plate 5 and the pitting corrosion potential at the lowest pitting corrosion potential in the thickness direction of the tank plate 5 <Junction between the header plate 4 and the tank plate 5 The relationship of the pitting corrosion potential of the part 8 is established.

[5. Al alloy fins]
[5.1 Composition of core material]
The core material of the Al alloy fin contains Si: 0.05 to 1.0%, Mn: 0.5 to 2.0%, Zn: 0.5 to 4.0%, and the remainder from Al and inevitable impurities Formed from an Al alloy.

(Si: 0.05-1.0%)
The core material of the Al alloy fin contains 0.05 to 1.0% of Si. When Si in the core material coexists with Mn, it becomes an Al-Mn-Si compound phase and is dispersed or dissolved in the matrix to improve the strength. The effect is small when the Si content is less than 0.05%. If it exceeds 1.0%, the precipitation amount of the Al—Si-based or Al—Mn—Si-based compound inside the core material increases, which may increase the corrosion rate of the fins.

(Mn: 0.5-2.0%)
The core material of the Al alloy fin contains 0.5 to 2.0% of Mn. Mn crystallizes or precipitates as an Al—Mn intermetallic compound, and improves the strength after brazing. Furthermore, an Al—Mn—Si compound is formed to lower the Si solid solubility in the matrix and improve the melting point of the matrix. If the Mn content is less than 0.5%, the effect is small, and if it exceeds 2.0%, a coarse Al—Mn-based compound phase is formed, so that the corrosion resistance and workability deteriorate.

(Zn: 0.5-4.0%)
In the core material of the Al alloy fin, 0.5 to 4.0% of Zn is contained. Zn has a function of solid-dissolving in Al and lowering the pitting potential. By making the pitting potential of the fin lower than the pitting potential of the heart of the tube, the fin can exert a sacrificial anticorrosive effect on the tube. In order to obtain this effect, 0.5% or more of Zn must be added. However, if the Zn concentration exceeds 4.0%, the corrosion rate of the fins increases.

(Ti, Zr, Cr, V: 0.05 to 0.3%)
The core material of the Al alloy fin may contain 0.05 to 0.3% of Ti, Zr, Cr, or V. These elements contribute to improvement of corrosion resistance, particularly pitting corrosion resistance. That is, Ti, Zr, Cr, or V added to the aluminum alloy is divided into a high concentration region and a low concentration region, and they are alternately distributed in the thickness direction. Then, the low concentration region corrodes preferentially over the high concentration region, so that the corrosion form becomes layered, and as a result, the progress of corrosion in the plate thickness direction is hindered, and the pitting corrosion resistance is improved. If the amount of Ti, Zr, Cr and V is less than 0.05%, such an effect of improving pitting corrosion resistance cannot be obtained sufficiently. On the other hand, if the amount of addition of Ti, Zr, Cr and V exceeds 0.3%, a coarse compound may be generated during casting, which may impair manufacturability.

(Fe: 0.05-1.0%)
The core material of the Al alloy fin may contain 0.05 to 1.0% Fe. Fe crystallizes or precipitates as an intermetallic compound and improves the core material strength.

(Mg: 0.05-1.0%)
The core material of the Al alloy fin may contain 0.05 to 1.0% of Mg. Mg has the effect of improving the strength of the core material.

[5.2 Composition of brazing material]
The brazing material of the Al alloy fin contains Si: 3.0 to 12.0%, and consists of the balance Al and inevitable impurities.

(Si: 3.0 to 12.0%)
The Al alloy fin brazing material contains 3.0 to 12.0% of Si. Si lowers the melting point of the aluminum alloy and produces a liquid phase, thereby enabling brazing. If the Si content is less than 3.0%, the liquid phase required for brazing cannot be sufficiently obtained, and the brazing property does not function satisfactorily. On the other hand, when the Si content exceeds 12.0%, coarse Si crystallizes during casting and cracks occur.

(Ti, Zr, Cr, V: 0.05 to 0.3%)
The brazing material of the Al alloy fin may contain 0.05 to 0.3% of Ti, Zr, Cr, or V. These elements contribute to improvement of corrosion resistance, particularly pitting corrosion resistance. That is, Ti, Zr, Cr, or V added to the aluminum alloy is divided into a high concentration region and a low concentration region, and they are alternately distributed in the thickness direction. Then, the low concentration region corrodes preferentially over the high concentration region, so that the corrosion form becomes layered. As a result, the progress of the corrosion in the plate thickness direction is hindered, and the pitting corrosion resistance is improved. In order to sufficiently obtain such an effect of improving the pitting corrosion resistance, the content of Ti, Zr, Cr or V is preferably 0.05% or more. On the other hand, if the content of Ti, Zr, Cr, or V exceeds 0.3%, a coarse compound is produced during casting, which may impair manufacturability.

(Fe, Ni: 0.05 to 1.0%)
The brazing material of the Al alloy fin may contain 0.05 to 1.0% of Fe or Ni. In general, Fe or Ni contributes to improvement of corrosion resistance.

(Mn: 0.05 to 1.5%)
The Al alloy fin brazing material may contain 0.05 to 1.5% of Mn. Mn is an element that crystallizes or precipitates as an Al—Mn intermetallic compound and contributes to the improvement of strength.

(Na, Sr: 10 ppm to 500 ppm)
The brazing material of the Al alloy fin may contain 10 ppm to 500 ppm of Na or Sr. Na and Sr have a function of refining the crystallized product of the Al—Si based alloy, and suppress the action of inhibiting corrosion resistance due to the concentration of corrosion on the coarse Al—Si based alloy particles.

(Zn: 0 to 3.0%)
The brazing material of the Al alloy fin may contain 0 to 3.0% of Zn. By adding Zn, the pitting corrosion potential of the fin is lowered. This produces a sacrificial anticorrosive effect and improves the life of the tube.

(Cu: 0.05-0.5%)
The Al alloy fin brazing material may contain 0.05 to 0.5% of Cu. Since the bonding between the fin and the tube is performed by the brazing material of the Al alloy fin, the pitting potential becomes higher as the Cu content increases, and the preferential corrosion of the bonded portion between the fin and the tube can be suppressed. .

[6. Manufacturing of heat exchanger]
The aluminum alloy heat exchanger 1 shown in FIG. 1 is assembled, for example, by first disposing the fins 3 on the outer surface of the tube 2 having both end portions attached to the header plates 4A and 4B. Tank plates 5A and 5B are attached to the header plates 4A and 4B, respectively. Next, both ends of the tube 2 are overlapped, the fin 3 and the outer surface of the tube 2, the both ends of the tube 2 and the header plates 4A and 4B, and the header plates 4A and 4B and the tank plates 5A and 5B are joined simultaneously by one brazing heating. .

  The brazing method used in the present invention includes a method using a fluoride flux in a nitrogen atmosphere (such as a Nocolok brazing method), and oxidation of the surface of the aluminum material with Mg contained in the material in a vacuum or nitrogen atmosphere. It is preferable to use a method of reducing and destroying the membrane (vacuum brazing, fluxless brazing). Brazing is usually performed by heating at a temperature of 590 to 610 ° C. for 2 to 10 minutes, preferably at a temperature of 590 to 610 ° C. for 2 to 6 minutes. If the heating time is less than 590 ° C. or the heating time is less than 2 minutes, brazing failure may occur. On the other hand, when the heating time exceeds 610 ° C. or the heating time exceeds 10 minutes, the member may be melted.

  Examples of the present invention will be described below together with comparative examples. The following examples are for explaining the effects of the present invention, and the processes, conditions and performance values described in the examples do not limit the technical scope of the present invention.

First, aluminum alloys (alloy numbers: A1 to A18) having the compositions shown in Table 1 were respectively melted and cast to produce billets having a diameter of 20 mm. Next, the billet was homogenized under the condition of holding at 550 ° C. for 10 hours, and then faced. Next, after heating the billet to 500 ° C., the billet is extruded, and the amount of Zn shown in Table 9 is thermally sprayed to obtain an aluminum alloy having a tube height of 1 mm, a width of 16 mm, and a wall thickness of 0.3 mm. A tube was prepared. This was cut to 200 mm to obtain a heat exchanger tube.

For the header plate material and the tank plate material, alloys of core materials (L0), L1, L2, L3, and L4 shown in Tables 2 to 6, respectively, were cast by a semi-continuous casting method and subjected to chamfering.

  Next, L1, L2, L3, or L4 is overlapped on one or both sides of the core material with a cladding ratio of 10% in the combinations shown in Tables 10 to 14, preheating is performed at 520 ° C. for 6 hours, and the sheet is obtained by hot rolling. The thickness was rolled to about 5 mm. Further, cold rolling and final annealing at 390 to 450 ° C. for 4 hours were performed to produce a brazing sheet having a thickness of about 1.6 mm. After cutting and molding this to 300 mm, 20 insertion holes for the tube were produced by burring, and used as a header plate for a heat exchanger. Moreover, the brazing sheet was cut into 300 mm and formed into a tank plate for a heat exchanger.

  For the fin material, alloys of core material and brazing material shown in Tables 7 and 8 were cast by a semi-continuous casting method and subjected to face cutting. Next, with the combinations shown in Table 15, the skin material was overlapped on both surfaces of the core material at a cladding rate of 10%, preheating was performed at 520 ° C. for 6 hours, and the plate thickness was rolled to about 5 mm by hot rolling. Further, cold rolling and final annealing at 390 to 450 ° C. for 4 hours were performed to produce a brazing sheet having a thickness of about 0.1 mm. This was slit to a width of 16 mm, corrugated, and used as a heat exchanger fin.

Fins were respectively arranged between the 20 tubes, both sides of the tube were inserted into the header plate, the header plate and the tank plate were fitted, and the heat exchanger was assembled. A KF-AlF-based flux (KAlF4, etc.) powder was applied and dried on this, and then brazed and heated in a nitrogen atmosphere at 600 ° C. for 5 minutes to cool to room temperature to obtain a heat exchanger.

The characteristics of the heat exchanger produced as described above were evaluated as follows.
(A) Pitting potential Each member was cut out from the heat exchanger, and the tube was etched every 0.01 mm from the surface to the core material, and then the surfaces other than the measurement surface were masked with an epoxy resin. The header plate and the tank plate were etched every 0.01 mm from the front surface to the front surface to 0.5 mm and from the back surface to the rear surface to 0.5 mm, and then the surfaces other than the measurement surface were masked with an epoxy resin. The joint portion was resin-filled in the joint portion and mirror-polished, and in the cross section, the portion other than the joint portion was masked with an epoxy resin. Using these as test materials, as a pretreatment, the surface was cleaned by immersion in a 5% NaOH solution at 60 ° C. for 30 seconds and immersion in a 30% HNO ₃ solution for 60 seconds. The solution was adjusted to pH 3 by adding acetic acid to 5% NaCl and degassed with nitrogen for 30 minutes. The measurement was performed at room temperature, and an anodic polarization curve was measured using a potentiostat. In the polarization curve, the potential at which the current suddenly increased was defined as the pitting potential.

  The pitting corrosion potential (A1) at the junction between the tube and the header plate, the pitting corrosion potential (B1) at the lowest pitting corrosion potential in the thickness direction of the tube, and the lowest pitting corrosion potential in the thickness direction of the header plate Pitting corrosion potential (B2) of the portion of the portion where the header plate and the tank plate are joined, Pitting corrosion potential (B2) of the portion having the lowest pitting corrosion potential in the thickness direction of the header plate, and the tank plate The pitting corrosion potential (B3) of the portion having the lowest pitting corrosion potential in the plate thickness direction was measured. When the respective pitting potentials satisfy A1> B1, A1> B2, A2> B2, and A2> B3, the pass (◯) was determined, and when the pitting potential was not satisfied, the reject (X) was determined.

(B) Corrosion resistance The heat exchanger was subjected to SWAAT according to ASTM G85 for 1000 hours. After the SWAAT test, a pressure resistance test was conducted to investigate leakage due to leakage and fin corrosion. If leak leakage does not occur, the corrosion resistance of the tube / header plate joint and header plate / tank plate joint shall be acceptable (○). If leak leakage occurs from the joint, the corrosion resistance of the joint will be rejected. (X). When the fin was not buckled by the pressure test, the corrosion resistance of the fin was accepted (◯), and when the fin was buckled, the corrosion resistance of the fin was rejected (x).

  Next, corrosion products on the surface of the heat exchanger were removed, and the corrosion depths of the tubes, header plates, and tank plates were measured. The number of measurement locations was 10 locations, and the maximum value was taken as the corrosion depth. In the tube, the case where the corrosion depth was less than 0.1 mm was determined to be acceptable (◯), and the case where the corrosion depth was 0.1 mm or more was determined to be unacceptable (x). In the header plate and the tank plate, the case where the corrosion depth was less than 0.5 mm was determined to be acceptable (◯), and the case where the corrosion depth was 0.5 mm or more and the case where it penetrated were determined to be unacceptable (x).

(C) If there was no problem in appearance defect or moldability due to manufacturability, it was judged as acceptable (◯), and if there was a problem in appearance defect such as cracking or moldability, it was rejected (x).

(Invention Examples 1-1 to 1-51 and Comparative Examples 1-1 to 1-26)
Table 16 shows an example of the heat exchanger having the structure of FIG. The brazed item described in the header plate and the tank plate indicates the joint surface between the header plate and the tank plate.

  In Invention Examples 1-1 to 1-51, all the pitting corrosion potential relationships satisfied the range defined in the present invention, and thus all the corrosion resistances were acceptable (O).

  On the other hand, in Comparative Example 1-1, since the Si concentration of the tube is low, the Mn solid solution amount increases, and the pitting corrosion potential of the tube becomes nobler than the pitting corrosion potential of the tube / header plate junction. It was. As a result, leak leakage occurred at the tube / header plate junction, which was a failure (x). Moreover, the corrosion resistance of the tube was also unacceptable (x).

  In Comparative Example 1-2, since the Si concentration of the tube was high, the extrudability was poor and subsequent evaluation could not be performed.

  In Comparative Example 1-3, since the Cu concentration of the tube is low, the Cu concentration of the tube / header plate joint is low, and the pitting corrosion potential of the tube / header plate joint is higher than the pitting corrosion potential of the tube and the header plate. I became obscene. As a result, leak leakage occurred at the tube / header plate junction, which was a failure (x). Moreover, the corrosion resistance of the tube was also unacceptable (x).

  In Comparative Example 1-4, since the Cu concentration of the tube was high, the tube was locally melted during brazing, and subsequent evaluation could not be performed.

  In Comparative Example 1-5, since the Mn concentration of the tube was low, the amount of Si solid solution was increased, and the pitting corrosion potential of the tube became more noble than the pitting corrosion potential of the tube / header plate junction. As a result, leak leakage occurred at the tube / header plate junction, which was a failure (x). Moreover, the corrosion resistance of the tube was also unacceptable (x).

  In Comparative Example 1-6, since the Mn concentration of the tube was high, the extrudability was poor and the subsequent evaluation could not be performed.

  In Comparative Example 1-7, since the tube was not sprayed with Zn, the corrosion resistance of the tube was rejected (x).

  In Comparative Example 1-8, although the amount of sprayed Zn on the tube is small, Zn was concentrated at the tube / header plate junction, so that the pitting corrosion potential at the tube / header plate junction was higher than the pitting corrosion potential at the tube / header plate. It became obscene. As a result, leak leakage occurred at the tube / header plate junction, which was a failure (x). Moreover, the corrosion resistance of the tube was also unacceptable (x).

  In Comparative Example 1-9, since the amount of Zn sprayed on the tube was large, Zn was concentrated in the tube / header plate junction, so the pitting corrosion potential of the tube / header plate junction was lower than the pitting corrosion potential of the header plate. became. As a result, leak leakage occurred at the tube / header plate junction, which was a failure (x).

  In Comparative Example 1-10, because the Si concentration of the brazing filler metal L1 of the header plate was low, the amount of brazing was insufficient and the brazing was poor, so that the subsequent evaluation could not be performed.

  In Comparative Example 1-11, since the Si concentration of the brazing filler metal L1 of the header plate was high, it was cracked during casting, so that subsequent evaluation could not be performed.

  In Comparative Example 1-12, since the Si concentration of the core material of the header plate was low, the Mn solid solution amount increased, and the pitting corrosion potential of the header plate became nobler than the pitting corrosion potential of the tube / header plate junction. . As a result, leak leakage occurred at the tube / header plate junction, which was a failure (x). Furthermore, the pitting corrosion potential of the header plate became nobler than the pitting corrosion potential of the header plate / tank plate junction. As a result, leak leakage occurred at the header plate / tank plate junction, which was a failure (x). Moreover, the corrosion resistance of the header plate was also rejected (x).

  In Comparative Example 1-13, since the Si concentration of the core material of the header plate was high, it was cracked during rolling, so that subsequent evaluation could not be performed.

  In Comparative Example 1-14, since the Cu concentration of the core material of the header plate is low, the Cu concentration of the tube / header plate junction is low, and the pitting corrosion potential of the tube / header plate junction is pitting corrosion of the tube and the header plate. It became lower than potential. As a result, leak leakage occurred at the tube / header plate junction, which was a failure (x). Moreover, the corrosion resistance of the header plate was also rejected (x).

  In Comparative Example 1-15, since the Cu concentration of the core material of the header plate was high, the header plate locally melted during brazing, and the subsequent evaluation could not be performed.

  In Comparative Example 1-16, since the Mn concentration of the core material of the header plate was low, the amount of Si solid solution increased, and the pitting corrosion potential of the header plate became nobler than the pitting corrosion potential of the tube / header plate junction. . As a result, leak leakage occurred at the tube / header plate junction, which was a failure (x). Furthermore, the pitting corrosion potential of the header plate became nobler than the pitting corrosion potential of the header plate / tank plate junction. As a result, leak leakage occurred at the header plate / tank plate junction, which was a failure (x). Moreover, the corrosion resistance of the header plate was also rejected (x).

  In Comparative Example 1-17, since the Mn concentration of the core material of the header plate was high, cracking occurred during rolling, and subsequent evaluation could not be performed.

  In Comparative Example 1-18, since the Si concentration of the brazing filler metal L2 of the tank plate was low, the amount of brazing was insufficient and the brazing was poor, so that the subsequent evaluation could not be performed.

  In Comparative Example 1-19, since the brazing filler metal L2 of the tank plate had a high Si concentration, it was cracked during casting, so that subsequent evaluation could not be performed.

  In Comparative Example 1-20, since the Si concentration of the core material of the tank plate is low, the Mn solid solution amount increases, and the pitting corrosion potential of the tank plate becomes nobler than the pitting corrosion potential of the header plate / tank plate junction. It was. As a result, leak leakage occurred at the header plate / tank plate junction, which was a failure (x). Moreover, the corrosion resistance of the tank plate was also unacceptable (x).

  In Comparative Example 1-21, since the Si concentration of the core material of the tank plate was high, cracking occurred during rolling, and subsequent evaluation could not be performed.

  In Comparative Example 1-22, since the Cu concentration in the core material of the tank plate is low, the Cu concentration in the header plate / tank plate junction is low, and the pitting potential at the header plate / tank plate junction is low. It became lower than the pitting corrosion potential. As a result, leak leakage occurred at the header plate / tank plate junction, which was a failure (x). Moreover, the corrosion resistance of the tank plate was also unacceptable (x).

  In Comparative Example 1-23, since the Cu concentration in the core material of the tank plate was high, the tank plate locally melted during brazing, and subsequent evaluation could not be performed.

  In Comparative Example 1-24, since the Mn concentration of the core material of the tank plate is low, the amount of Si solid solution increases, and the pitting corrosion potential of the tank plate becomes nobler than the pitting corrosion potential of the header plate / tank plate junction. It was. As a result, leak leakage occurred at the header plate / tank plate junction, which was a failure (x). Moreover, the corrosion resistance of the tank plate was also unacceptable (x).

  In Comparative Example 1-25, since the Mn concentration of the core material of the tank plate was high, cracking occurred during rolling, and subsequent evaluation could not be performed.

  In Comparative Example 1-26, the joint surface between the header plate and the tank plate was inappropriate, so the pitting corrosion potential at the header plate / tank plate joint was lower than the pitting corrosion potential at the header plate and the tank plate. As a result, leak leakage occurred at the header plate / tank plate junction, which was a failure (x).

(Invention Examples 2-1 to 2-51 and Comparative Examples 2-1 to 2-27)
Table 17 shows an example of the heat exchanger having the structure of FIG. The brazed item described in the header plate and the tank plate indicates the joint surface between the header plate and the tank plate.

  In Invention Examples 2-1 to 2-51, all the pitting corrosion potential relationships satisfied the range defined in the present invention, and therefore all the corrosion resistances were acceptable (O).

  On the other hand, in Comparative Example 2-1, since the Si concentration of the tube is low, the Mn solid solution amount increases, and the pitting corrosion potential of the tube becomes nobler than the pitting corrosion potential of the tube / header plate junction. It was. As a result, leak leakage occurred at the tube / header plate junction, which was a failure (x). Moreover, the corrosion resistance of the tube was also unacceptable (x).

  In Comparative Example 2-2, since the Si concentration in the tube was high, the extrudability was poor and subsequent evaluation could not be performed.

  In Comparative Example 2-3, since the Cu concentration of the tube is low, the Cu concentration of the tube / header plate joint is low, and the pitting corrosion potential of the tube / header plate joint is higher than the pitting corrosion potential of the tube and the header plate. I became obscene. As a result, leak leakage occurred at the tube / header plate junction, which was a failure (x). Moreover, the corrosion resistance of the tube was also unacceptable (x).

  In Comparative Example 2-4, since the Cu concentration of the tube was high, the tube was locally melted during brazing, and subsequent evaluation could not be performed.

  In Comparative Example 2-5, since the Mn concentration of the tube was low, the amount of Si solid solution was increased, and the pitting corrosion potential of the tube became more noble than the pitting corrosion potential of the tube / header plate junction. As a result, leak leakage occurred at the tube / header plate junction, which was a failure (x). Moreover, the corrosion resistance of the tube was also unacceptable (x).

  In Comparative Example 2-6, since the Mn concentration in the tube was high, the extrudability was poor and subsequent evaluation could not be performed.

  In Comparative Example 2-7, since the Zn spraying was not performed on the tube, the corrosion resistance of the tube was rejected (x).

  In Comparative Example 2-8, although the amount of Zn sprayed on the tube is small, Zn was concentrated in the tube / header plate junction, so that the pitting corrosion potential of the tube / header plate junction is higher than the pitting corrosion potential of the tube and header plate. I became obscene. As a result, leak leakage occurred at the tube / header plate junction, which was a failure (x). Moreover, the corrosion resistance of the tube was also unacceptable (x).

  In Comparative Example 2-9, since the amount of Zn sprayed on the tube was large, Zn was concentrated in the tube / header plate junction, so the pitting corrosion potential of the tube / header plate junction was lower than the pitting corrosion potential of the header plate. became. As a result, leak leakage occurred at the tube / header plate junction, which was a failure (x).

  In Comparative Example 2-10, because the Si concentration of the brazing material L1 of the tank plate was low, the amount of brazing was insufficient and the brazing was poor, so that the subsequent evaluation could not be performed.

  In Comparative Example 2-11, since the Si concentration of the brazing filler metal L1 of the tank plate was high, it was cracked during casting, so that subsequent evaluation could not be performed.

  In Comparative Example 2-12, since the Si concentration of the core material of the tank plate is low, the Mn solid solution amount increases, and the pitting corrosion potential of the tank plate becomes nobler than the pitting corrosion potential of the header plate / tank plate junction. It was. As a result, leak leakage occurred at the header plate / tank plate junction, which was a failure (x). Moreover, the corrosion resistance of the tank plate was also unacceptable (x).

  In Comparative Example 2-13, since the Si concentration of the core material of the tank plate was high, cracking occurred during rolling, and subsequent evaluation could not be performed.

  In Comparative Example 2-14, since the Cu concentration of the core material of the tank plate is low, the Cu concentration of the tube / header plate junction is low, and the pitting corrosion potential of the header plate / tank plate junction is low between the header plate and the tank plate. It became lower than the pitting corrosion potential. As a result, leak leakage occurred at the header plate / tank plate junction, which was a failure (x). Moreover, the corrosion resistance of the tank plate was also unacceptable (x).

  In Comparative Example 2-15, since the Cu concentration of the core material of the tank plate was high, the header plate was locally melted during brazing, and subsequent evaluation could not be performed.

  In Comparative Example 2-16, since the Mn concentration of the core material of the tank plate is low, the amount of Si solid solution is increased, and the pitting corrosion potential of the tank plate becomes higher than the pitting corrosion potential of the header plate / tank plate junction. It was. As a result, leak leakage occurred at the header plate / tank plate junction, which was a failure (x). Moreover, the corrosion resistance of the tank plate was also unacceptable (x).

  In Comparative Example 2-17, since the Mn concentration of the core material of the tank plate was high, it was cracked during rolling, so that subsequent evaluation could not be performed.

  In Comparative Example 2-18, since the Si concentration of the brazing filler metal L2 of the header plate was low, the amount of the brazing was insufficient and the brazing was poor, so that the subsequent evaluation could not be performed.

  In Comparative Example 2-19, since the Si concentration of the brazing filler metal L2 of the header plate was high, it was cracked during casting, so that subsequent evaluation could not be performed.

  In Comparative Example 2-20, since the Zn concentration in the brazing filler metal L2 of the header plate was high, Zn was concentrated in the tube / header plate junction, so the pitting corrosion potential at the tube / header plate junction was It became lower than the pitting corrosion potential. As a result, leak leakage occurred at the tube / header plate junction, which was a failure (x).

  In Comparative Example 2-21, since the Si concentration of the core material of the header plate was low, the Mn solid solution amount increased, and the pitting corrosion potential of the header plate became nobler than the pitting corrosion potential of the tube / header plate junction. . As a result, leak leakage occurred at the tube / header plate junction, which was a failure (x). Furthermore, the pitting corrosion potential of the header plate became nobler than the pitting corrosion potential of the header plate / tank plate junction. As a result, leak leakage occurred at the header plate / tank plate junction, which was a failure (x). Moreover, the corrosion resistance of the header plate was also rejected (x).

  In Comparative Example 2-22, since the Si concentration of the core material of the header plate was high, it was cracked during rolling, so that subsequent evaluation could not be performed.

  In Comparative Example 2-23, since the Cu concentration of the core material of the header plate is low, the Cu concentration of the tube / header plate joint portion is low, and the pitting corrosion potential of the tube / header plate joint portion is pitting corrosion of the tube and the header plate. It became lower than potential. As a result, leak leakage occurred at the tube / header plate junction, which was a failure (x). Moreover, the corrosion resistance of the header plate was also rejected (x).

  In Comparative Example 2-24, since the Cu concentration of the core material of the header plate was high, the header plate locally melted during brazing, and subsequent evaluation could not be performed.

  In Comparative Example 2-25, since the Mn concentration of the core material of the header plate was low, the amount of Si solid solution increased, and the pitting corrosion potential of the header plate became nobler than the pitting corrosion potential of the tube / header plate junction. . As a result, leak leakage occurred at the tube / header plate junction, which was a failure (x). Furthermore, the pitting corrosion potential of the header plate became nobler than the pitting corrosion potential of the header plate / tank plate junction. As a result, leak leakage occurred at the header plate / tank plate junction, which was a failure (x). Moreover, the corrosion resistance of the header plate was also rejected (x).

  In Comparative Example 2-26, since the Mn concentration of the core material of the header plate was high, cracking occurred during rolling, and subsequent evaluation could not be performed.

  In Comparative Example 2-27, the joint surface between the header plate and the tank plate was unsuitable, so the pitting corrosion potential at the header plate / tank plate joint was lower than the pitting corrosion potential at the header plate and the tank plate. As a result, leak leakage occurred at the header plate / tank plate junction, which was a failure (x).

(Invention Examples 3-1 to 3-58 and Comparative Examples 3-1 to 3-29)
Table 18 shows an example of the heat exchanger having the structure of FIG. The brazed item described in the header plate and the tank plate indicates the joint surface between the header plate and the tank plate.

  In Invention Examples 3-1 to 3-58, all the pitting corrosion potential relationships satisfied the range defined in the present invention, and therefore all the corrosion resistances were acceptable (◯).

  On the other hand, in Comparative Example 3-1, since the Si concentration of the tube is low, the Mn solid solution amount increases, and the pitting corrosion potential of the tube becomes nobler than the pitting corrosion potential of the tube / header plate junction. It was. As a result, leak leakage occurred at the tube / header plate junction, which was a failure (x). Moreover, the corrosion resistance of the tube was also unacceptable (x).

  In Comparative Example 3-2, since the Si concentration of the tube was high, the extrudability was poor and subsequent evaluation could not be performed.

  In Comparative Example 3-3, since the Cu concentration of the tube is low, the Cu concentration of the tube / header plate joint is low, and the pitting corrosion potential of the tube / header plate joint is higher than the pitting corrosion potential of the tube and the header plate. I became obscene. As a result, leak leakage occurred at the tube / header plate junction, which was a failure (x). Moreover, the corrosion resistance of the tube was also unacceptable (x).

  In Comparative Example 3-4, since the Cu concentration of the tube was high, the tube was locally melted during brazing, and subsequent evaluation could not be performed.

  In Comparative Example 3-5, since the Mn concentration in the tube was low, the amount of Si solid solution increased, and the pitting corrosion potential of the tube became more noble than the pitting corrosion potential of the tube / header plate junction. As a result, leak leakage occurred at the tube / header plate junction, which was a failure (x). Moreover, the corrosion resistance of the tube was also unacceptable (x).

  In Comparative Example 3-6, since the Mn concentration of the tube was high, the extrudability was poor and subsequent evaluation could not be performed.

  In Comparative Example 3-7, the tube was not sprayed with Zn, and thus the corrosion resistance of the tube was rejected (x).

  In Comparative Example 3-8, although the amount of sprayed Zn on the tube is small, Zn was concentrated in the tube / header plate junction, so that the pitting corrosion potential of the tube / header plate junction was higher than the pitting corrosion potential of the tube and header plate. It became obscene. As a result, leak leakage occurred at the tube / header plate junction, which was a failure (x). Moreover, the corrosion resistance of the tube was also unacceptable (x).

  In Comparative Example 3-9, since the amount of Zn sprayed on the tube was large, Zn was concentrated in the tube / header plate junction, so the pitting corrosion potential of the tube / header plate junction was lower than the pitting corrosion potential of the header plate. became. As a result, leak leakage occurred at the tube / header plate junction, which was a failure (x).

  In Comparative Example 3-10, because the Si concentration of the brazing filler metal L2 of the header plate was low, the amount of brazing was insufficient and the brazing was poor, so that the subsequent evaluation could not be performed.

  In Comparative Example 3-11, since the brazing filler metal L2 of the header plate had a high Si concentration, it was cracked during casting, and subsequent evaluation could not be performed.

  In Comparative Example 3-12, since the Zn concentration in the brazing filler metal L2 of the header plate was high, Zn was concentrated in the tube / header plate junction, so that the pitting corrosion potential at the tube / header plate junction was It became lower than the pitting corrosion potential. As a result, leak leakage occurred at the tube / header plate junction, which was a failure (x). Furthermore, since Zn was concentrated in the header plate / tank plate junction, the pitting corrosion potential of the header plate / tank plate junction became lower than the pitting corrosion potential of the header plate and the tank plate. As a result, leak leakage occurred at the header plate / tank plate junction, which was a failure (x).

  In Comparative Example 3-13, since the Si concentration of the core material of the header plate was low, the Mn solid solution amount increased, and the pitting corrosion potential of the header plate became nobler than the pitting corrosion potential of the tube / header plate junction. . As a result, leak leakage occurred at the tube / header plate junction, which was a failure (x). Furthermore, the pitting corrosion potential of the header plate became nobler than the pitting corrosion potential of the header plate / tank plate junction. As a result, leak leakage occurred at the header plate / tank plate junction, which was a failure (x). Moreover, the corrosion resistance of the header plate was also rejected (x).

  In Comparative Example 3-14, since the Si concentration of the core material of the header plate was high, it was cracked during rolling, and subsequent evaluation could not be performed.

  In Comparative Example 3-15, since the Cu concentration of the core material of the header plate is low, the Cu concentration of the tube / header plate joint is low, and the pitting corrosion potential of the tube / header plate joint is pitting corrosion of the tube and the header plate. It became lower than potential. As a result, leak leakage occurred at the tube / header plate junction, which was a failure (x). Furthermore, the Cu concentration at the header plate / tank plate junction was low, and the pitting corrosion potential at the header plate / tank plate junction was lower than the pitting corrosion potential at the header plate and tank plate. As a result, leak leakage occurred at the header plate / tank plate junction, which was a failure (x). Moreover, the corrosion resistance of the header plate was also rejected (x).

  In Comparative Example 3-16, since the Cu concentration of the core material of the header plate was high, the header plate locally melted during brazing, and subsequent evaluation could not be performed.

  In Comparative Example 3-17, since the Mn concentration of the core material of the header plate was low, the amount of Si solid solution increased, and the pitting corrosion potential of the header plate became nobler than the pitting corrosion potential of the tube / header plate junction. . As a result, leak leakage occurred at the tube / header plate junction, which was a failure (x). Furthermore, the pitting corrosion potential of the header plate became nobler than the pitting corrosion potential of the header plate / tank plate junction. As a result, leak leakage occurred at the header plate / tank plate junction, which was a failure (x). Moreover, the corrosion resistance of the header plate was also rejected (x).

  In Comparative Example 3-18, since the Mn concentration of the core material of the header plate was high, cracking occurred during rolling, and subsequent evaluation could not be performed.

  In Comparative Example 3-19, since the brazing material L2 of the tank plate had a low Si concentration, the amount of the brazing was insufficient and the brazing was poor, so that the subsequent evaluation could not be performed.

  In Comparative Example 3-20, the brazing material L2 of the tank plate had a high Si concentration, and therefore cracked during casting.

  In Comparative Example 3-21, since the Si concentration of the core material of the tank plate is low, the Mn solid solution amount increases, and the pitting corrosion potential of the tank plate becomes more noble than the pitting corrosion potential of the header plate / tank plate junction. It was. As a result, leak leakage occurred at the header plate / tank plate junction, which was a failure (x). Moreover, the corrosion resistance of the tank plate was also unacceptable (x).

  In Comparative Example 3-22, since the Si concentration of the core material of the tank plate was high, cracking occurred during rolling, and subsequent evaluation could not be performed.

  In Comparative Example 3-23, since the Cu concentration in the core material of the tank plate was high, the tank plate locally melted during brazing, and subsequent evaluation could not be performed.

  In Comparative Example 3-24, since the Mn concentration of the core material of the tank plate is low, the amount of Si solid solution increases, and the pitting corrosion potential of the tank plate becomes nobler than the pitting corrosion potential of the header plate / tank plate junction. It was. As a result, leak leakage occurred at the header plate / tank plate junction, which was a failure (x). Moreover, the corrosion resistance of the tank plate was also unacceptable (x).

  In Comparative Example 3-25, since the Mn concentration of the core material of the tank plate was high, it was cracked during rolling, and subsequent evaluation could not be performed.

  In Comparative Example 3-26, since the Si concentration of the brazing material L3 of the tank plate is low, the movement of Cu to the header plate / tank plate junction is not sufficient, and the Cu concentration to the header plate / tank plate junction is low. The header plate / tank plate junction pitting potential was lower than the header plate and tank plate pitting potential. As a result, leak leakage occurred at the header plate / tank plate junction, which was a failure (x).

  In Comparative Example 3-27, since the Si concentration of the brazing filler metal L3 of the tank plate was high, it was cracked during casting, so that subsequent evaluation could not be performed.

  In Comparative Example 3-28, since the Cu concentration of the brazing material L3 of the tank plate was high, it was cracked during casting, so that subsequent evaluation could not be performed.

  In Comparative Example 3-29, the joint surface between the header plate and the tank plate was inappropriate, so the pitting corrosion potential at the header plate / tank plate joint was lower than the pitting corrosion potential at the header plate and the tank plate. As a result, leak leakage occurred at the header plate / tank plate junction, which was a failure (x).

(Invention Examples 4-1 to 4-58 and Comparative Examples 4-1 to 4-31)
Table 19 shows examples of the heat exchanger having the structure shown in FIG. The brazed item described in the header plate and the tank plate indicates the joint surface between the header plate and the tank plate.

  In Invention Examples 4-1 to 4-58, all the pitting corrosion potential relationships satisfied the range defined in the present invention, and therefore all the corrosion resistances were acceptable (O).

  On the other hand, in Comparative Example 4-1, since the Si concentration of the tube is low, the Mn solid solution amount increases, and the pitting corrosion potential of the tube becomes nobler than the pitting corrosion potential of the tube / header plate junction. It was. As a result, leak leakage occurred at the tube / header plate junction, which was a failure (x). Moreover, the corrosion resistance of the tube was also unacceptable (x).

  In Comparative Example 4-2, since the Si concentration of the tube was high, the extrudability was poor and subsequent evaluation could not be performed.

  In Comparative Example 4-3, since the Cu concentration of the tube is low, the Cu concentration of the tube / header plate joint is low, and the pitting corrosion potential of the tube / header plate joint is higher than the pitting corrosion potential of the tube and the header plate. I became obscene. As a result, leak leakage occurred at the tube / header plate junction, which was a failure (x). Moreover, the corrosion resistance of the tube was also unacceptable (x).

  In Comparative Example 4-4, since the Cu concentration of the tube was high, the tube was locally melted during brazing, and subsequent evaluation could not be performed.

  In Comparative Example 4-5, since the Mn concentration of the tube was low, the amount of Si solid solution increased, and the pitting corrosion potential of the tube became more noble than the pitting corrosion potential of the tube / header plate junction. As a result, leak leakage occurred at the tube / header plate junction, which was a failure (x). Moreover, the corrosion resistance of the tube was also unacceptable (x).

  In Comparative Example 4-6, since the Mn concentration in the tube was high, the extrudability was poor and the subsequent evaluation could not be performed.

  In Comparative Example 4-7, Zn spraying was not performed on the tube, so the corrosion resistance of the tube was rejected (x).

  In Comparative Example 4-8, although the amount of sprayed Zn on the tube is small, Zn was concentrated at the tube / header plate junction, so the pitting corrosion potential at the tube / header plate junction was higher than the pitting corrosion potential at the tube / header plate. I became obscene. As a result, leak leakage occurred at the tube / header plate junction, which was a failure (x). Moreover, the corrosion resistance of the tube was also unacceptable (x).

  In Comparative Example 4-9, since the amount of Zn sprayed on the tube was large, Zn was concentrated in the tube / header plate junction, so the pitting corrosion potential of the tube / header plate junction was lower than the pitting corrosion potential of the header plate. became. As a result, leak leakage occurred at the tube / header plate junction, which was a failure (x).

  In Comparative Example 4-10, because the Si concentration of the brazing filler metal L2 of the tank plate was low, the amount of brazing was insufficient and the brazing was poor, so that the subsequent evaluation could not be performed.

  In Comparative Example 4-11, since the brazing filler metal L2 of the tank plate had a high Si concentration, it was cracked during casting, so that subsequent evaluation could not be performed.

  In Comparative Example 4-12, since the Zn concentration in the brazing material L2 of the tank plate was high, Zn was concentrated in the header plate / tank plate junction, so that the pitting potential at the header plate / tank plate junction was It became lower than the pitting corrosion potential of the tank plate. As a result, leak leakage occurred at the header plate / tank plate junction, which was a failure (x).

  In Comparative Example 4-13, since the Si concentration of the core material of the tank plate is low, the Mn solid solution amount increases, and the pitting corrosion potential of the tank plate becomes nobler than the pitting corrosion potential of the header plate / tank plate junction. It was. As a result, leak leakage occurred at the header plate / tank plate junction, which was a failure (x). Moreover, the corrosion resistance of the tank plate was also unacceptable (x).

  In Comparative Example 4-14, since the Si concentration of the core material of the tank plate was high, cracking occurred during rolling, and subsequent evaluation could not be performed.

  In Comparative Example 4-15, since the Cu concentration in the core material of the tank plate is low, the Cu concentration in the header plate / tank plate junction is low, and the pitting potential at the header plate / tank plate junction is low. It became lower than the pitting corrosion potential. As a result, leak leakage occurred at the header plate / tank plate junction, which was a failure (x). Moreover, the corrosion resistance of the header plate was also rejected (x).

  In Comparative Example 4-16, since the Cu concentration in the core material of the tank plate was high, the tank plate locally melted during brazing, and subsequent evaluation could not be performed.

  In Comparative Example 4-17, since the Mn concentration of the core material of the tank plate is low, the amount of Si solid solution increases, and the pitting corrosion potential of the tank plate becomes nobler than the pitting corrosion potential of the header plate / tank plate junction. It was. As a result, leak leakage occurred at the header plate / tank plate junction, which was a failure (x). Moreover, the corrosion resistance of the tank plate was also unacceptable (x).

  In Comparative Example 4-18, since the Mn concentration of the core material of the tank plate was high, cracking occurred during rolling, and subsequent evaluation could not be performed.

  In Comparative Example 4-19, since the Si concentration of the brazing filler metal L2 of the header plate was low, the amount of brazing was insufficient and the brazing was poor, so that the subsequent evaluation could not be performed.

  In Comparative Example 4-20, since the Si concentration of the brazing filler metal L2 of the header plate was high, it was cracked during casting, so that subsequent evaluation could not be performed.

  In Comparative Example 4-21, since the Zn concentration of the brazing filler metal L2 of the header plate was high, Zn was concentrated in the tube / header plate junction, so the pitting corrosion potential of the tube / header plate junction was It became lower than the pitting corrosion potential. As a result, leak leakage occurred at the tube / header plate junction, which was a failure (x).

  In Comparative Example 4-22, since the Si concentration of the core material of the header plate was low, the Mn solid solution amount increased, and the pitting corrosion potential of the header plate became nobler than the pitting corrosion potential of the tube / header plate junction. . As a result, leak leakage occurred at the tube / header plate junction, which was a failure (x). Furthermore, the pitting corrosion potential of the header plate became nobler than the pitting corrosion potential of the header plate / tank plate junction. As a result, leak leakage occurred at the header plate / tank plate junction, which was a failure (x). Moreover, the corrosion resistance of the header plate was also rejected (x).

  In Comparative Example 4-23, since the Si concentration of the core material of the header plate was high, it was cracked during rolling, so that subsequent evaluation could not be performed.

  In Comparative Example 4-24, since the Cu concentration of the core material of the header plate is low, the Cu concentration of the tube / header plate joint is low, and the pitting corrosion potential of the tube / header plate joint is pitting corrosion of the tube and the header plate. It became lower than potential. As a result, leak leakage occurred at the tube / header plate junction, which was a failure (x). Moreover, the corrosion resistance of the header plate was also rejected (x).

  In Comparative Example 4-25, since the Cu concentration of the core material of the header plate was high, the tank plate locally melted during brazing, and subsequent evaluation could not be performed.

  In Comparative Example 4-26, since the Mn concentration of the core material of the header plate was low, the amount of Si solid solution increased, and the pitting corrosion potential of the header plate became nobler than the pitting corrosion potential of the tube / header plate junction. . As a result, leak leakage occurred at the tube / header plate junction, which was a failure (x). Furthermore, the pitting corrosion potential of the header plate became nobler than the pitting corrosion potential of the header plate / tank plate junction. As a result, leak leakage occurred at the header plate / tank plate junction, which was a failure (x). Moreover, the corrosion resistance of the header plate was also rejected (x).

  In Comparative Example 4-27, since the Mn concentration of the core material of the header plate was high, it was cracked during rolling, so that subsequent evaluation could not be performed.

  In Comparative Example 4-28, since the Si concentration of the brazing filler metal L3 of the header plate is low, the movement of Cu to the header plate / tank plate junction is not sufficient, and the Cu concentration to the header plate / tank plate junction is low. The header plate / tank plate junction pitting potential was lower than the header plate and tank plate pitting potential. As a result, leak leakage occurred at the header plate / tank plate junction, which was a failure (x).

  In Comparative Example 4-29, since the Si concentration of the brazing filler metal L3 of the header plate was high, it was cracked during casting, so that subsequent evaluation could not be performed.

  In Comparative Example 4-30, since the Cu concentration of the brazing filler metal L3 of the header plate was high, it was cracked during casting, so that subsequent evaluation could not be performed.

  In Comparative Example 4-31, the joint surface between the header plate and the tank plate was unsuitable, so the pitting corrosion potential at the header plate / tank plate joint was lower than the pitting corrosion potential at the header plate and the tank plate. As a result, leak leakage occurred at the header plate / tank plate junction, which was a failure (x).

(Invention Examples 5-1 to 5-56 and Comparative Examples 5-1 to 5-27)
Table 20 shows an example of the heat exchanger having the structure of FIG. The brazed item described in the header plate and the tank plate indicates the joint surface between the header plate and the tank plate.

  In Invention Examples 5-1 to 5-56, all the pitting corrosion potential relationships satisfied the range defined in the present invention, and therefore all the corrosion resistances were acceptable (O).

  On the other hand, in Comparative Example 5-1, since the Si concentration of the tube is low, the Mn solid solution amount increases, and the pitting corrosion potential of the tube becomes nobler than the pitting corrosion potential of the tube / header plate junction. It was. As a result, leak leakage occurred at the tube / header plate junction, which was a failure (x). Moreover, the corrosion resistance of the tube was also unacceptable (x).

  In Comparative Example 5-2, since the Si concentration of the tube was high, the extrudability was poor and subsequent evaluation could not be performed.

  In Comparative Example 5-3, since the Cu concentration of the tube is low, the Cu concentration of the tube / header plate joint is low, and the pitting corrosion potential of the tube / header plate joint is higher than the pitting corrosion potential of the tube and the header plate. I became obscene. As a result, leak leakage occurred at the tube / header plate junction, which was a failure (x). Moreover, the corrosion resistance of the tube was also unacceptable (x).

  In Comparative Example 5-4, since the Cu concentration of the tube was high, the tube locally melted during brazing, and subsequent evaluation could not be performed.

  In Comparative Example 5-5, since the Mn concentration of the tube was low, the amount of Si solid solution was increased, and the pitting corrosion potential of the tube became more noble than the pitting corrosion potential of the tube / header plate junction. As a result, leak leakage occurred at the tube / header plate junction, which was a failure (x). Moreover, the corrosion resistance of the tube was also unacceptable (x).

  In Comparative Example 5-6, since the Mn concentration in the tube was high, the extrudability was poor and the subsequent evaluation could not be performed.

  In Comparative Example 5-7, since the Zn spraying was not performed on the tube, the corrosion resistance of the tube was rejected (x).

  In Comparative Example 5-8, although the amount of Zn sprayed on the tube is small, Zn was concentrated at the tube / header plate junction, so the pitting corrosion potential at the tube / header plate junction was higher than the pitting corrosion potential at the tube / header plate. I became obscene. As a result, leak leakage occurred at the tube / header plate junction, which was a failure (x). Moreover, the corrosion resistance of the tube was also unacceptable (x).

  In Comparative Example 5-9, since the amount of Zn sprayed on the tube was large, Zn was concentrated in the tube / header plate junction, so the pitting corrosion potential of the tube / header plate junction was lower than the pitting corrosion potential of the header plate. became. As a result, leak leakage occurred at the tube / header plate junction, which was a failure (x).

  In Comparative Example 5-10, since the Si concentration of the brazing filler metal L2 of the header plate was low, the amount of brazing was insufficient and the brazing was poor, so that the subsequent evaluation could not be performed.

  In Comparative Example 5-11, since the Si concentration of the brazing filler metal L2 of the header plate was high, it was cracked during casting, so that subsequent evaluation could not be performed.

  In Comparative Example 5-12, since the Zn concentration of the brazing filler metal L2 of the header plate was high, Zn was concentrated in the tube / header plate junction, so the pitting corrosion potential of the tube / header plate junction was It became lower than the pitting corrosion potential. As a result, leak leakage occurred at the tube / header plate junction, which was a failure (x). Furthermore, since Zn was concentrated in the header plate / tank plate junction, the pitting corrosion potential of the header plate / tank plate junction became lower than the pitting corrosion potential of the header plate and the tank plate. As a result, leak leakage occurred at the header plate / tank plate junction, which was a failure (x).

  In Comparative Example 5-13, since the Si concentration of the core material of the header plate was low, the amount of Mn solid solution increased, and the pitting corrosion potential of the header plate became nobler than the pitting corrosion potential of the tube / header plate junction. . As a result, leak leakage occurred at the tube / header plate junction, which was a failure (x). Furthermore, the pitting corrosion potential of the header plate became nobler than the pitting corrosion potential of the header plate / tank plate junction. As a result, leak leakage occurred at the header plate / tank plate junction, which was a failure (x). Moreover, the corrosion resistance of the header plate was also rejected (x).

  In Comparative Example 5-14, since the Si concentration of the core material of the header plate was high, cracking occurred during rolling, and subsequent evaluation could not be performed.

  In Comparative Example 5-15, since the Cu concentration of the core material of the header plate is low, the Cu concentration of the tube / header plate junction is low, and the pitting corrosion potential of the tube / header plate junction is pitting corrosion of the tube and header plate. It became lower than potential. As a result, leak leakage occurred at the tube / header plate junction, which was a failure (x). Furthermore, the Cu concentration at the header plate / tank plate junction was low, and the pitting corrosion potential at the header plate / tank plate junction was lower than the pitting corrosion potential at the header plate and tank plate. As a result, leak leakage occurred at the header plate / tank plate junction, which was a failure (x). Moreover, the corrosion resistance of the header plate was also rejected (x).

  In Comparative Example 5-16, since the Cu concentration of the core material of the header plate was high, the header plate locally melted during brazing, and the subsequent evaluation could not be performed.

  In Comparative Example 5-17, since the Mn concentration of the core material of the header plate was low, the amount of Si solid solution increased, and the pitting corrosion potential of the header plate became nobler than the pitting corrosion potential of the tube / header plate junction. . As a result, leak leakage occurred at the tube / header plate junction, which was a failure (x). Furthermore, the pitting corrosion potential of the header plate became nobler than the pitting corrosion potential of the header plate / tank plate junction. As a result, leak leakage occurred at the header plate / tank plate junction, which was a failure (x). Moreover, the corrosion resistance of the header plate was also rejected (x).

  In Comparative Example 5-18, since the Mn concentration of the core material of the header plate was high, cracking occurred during rolling, and subsequent evaluation could not be performed.

  In Comparative Example 5-19, since the Si concentration of the core material of the tank plate is low, the Mn solid solution amount increases, and the pitting corrosion potential of the tank plate becomes nobler than the pitting corrosion potential of the header plate / tank plate junction. It was. As a result, leak leakage occurred at the header plate / tank plate junction, which was a failure (x). Moreover, the corrosion resistance of the tank plate was also unacceptable (x).

  In Comparative Example 5-20, since the Si concentration of the core material of the tank plate was high, cracking occurred during rolling, and subsequent evaluation could not be performed.

  In Comparative Example 5-21, since the Cu concentration in the core material of the tank plate was high, the tank plate locally melted during brazing, and subsequent evaluation could not be performed.

  In Comparative Example 5-22, since the Mn concentration of the core material of the tank plate is low, the amount of Si solid solution increases, and the pitting corrosion potential of the tank plate becomes nobler than the pitting corrosion potential of the header plate / tank plate junction. It was. As a result, leak leakage occurred at the header plate / tank plate junction, which was a failure (x). Moreover, the corrosion resistance of the tank plate was also unacceptable (x).

  In Comparative Example 5-23, since the Mn concentration of the core material of the tank plate was high, cracking occurred during rolling, and subsequent evaluation could not be performed.

  In Comparative Example 5-24, since the Si concentration of the brazing material L3 of the tank plate is low, the movement of Cu to the header plate / tank plate junction is not sufficient, and the Cu concentration to the header plate / tank plate junction is low. The header plate / tank plate junction pitting potential was lower than the header plate and tank plate pitting potential. As a result, leak leakage occurred at the header plate / tank plate junction, which was a failure (x).

  In Comparative Example 5-25, since the Si concentration of the brazing filler metal L3 of the tank plate was high, it was cracked during casting, so that subsequent evaluation could not be performed.

  In Comparative Example 5-26, since the Cu concentration of the brazing material L3 of the tank plate was high, it was cracked at the time of casting, so that subsequent evaluation could not be performed.

  In Comparative Example 5-27, the header plate / tank plate joint was not brazed because the joint surface between the header plate and the tank plate was not brazed. As a result, leak leakage occurred at the header plate / tank plate junction, which was a failure (x).

(Invention Examples 6-1 to 6-56 and Comparative Examples 6-1 to 6-29)
Table 21 shows an example of a heat exchanger having the structure of FIG. The brazed item described in the header plate and the tank plate indicates the joint surface between the header plate and the tank plate.

  In Invention Examples 6-1 to 6-56, all the pitting corrosion potential relationships satisfied the range defined in the present invention, and therefore all the corrosion resistances were acceptable (O).

  On the other hand, in Comparative Example 6-1, since the Si concentration of the tube is low, the Mn solid solution amount increases, and the pitting corrosion potential of the tube becomes nobler than the pitting corrosion potential of the tube / header plate junction. It was. As a result, leak leakage occurred at the tube / header plate junction, which was a failure (x). Moreover, the corrosion resistance of the tube was also unacceptable (x).

  In Comparative Example 6-2, since the Si concentration of the tube was high, the extrudability was poor and subsequent evaluation could not be performed.

  In Comparative Example 6-3, since the Cu concentration of the tube is low, the Cu concentration of the tube / header plate joint is low, and the pitting corrosion potential of the tube / header plate joint is higher than the pitting corrosion potential of the tube and the header plate. I became obscene. As a result, leak leakage occurred at the tube / header plate junction, which was a failure (x). Moreover, the corrosion resistance of the tube was also unacceptable (x).

  In Comparative Example 6-4, since the Cu concentration of the tube was high, the tube was locally melted during brazing, and subsequent evaluation could not be performed.

  In Comparative Example 6-5, since the Mn concentration of the tube was low, the amount of Si solid solution increased, and the pitting corrosion potential of the tube became more noble than the pitting corrosion potential of the tube / header plate junction. As a result, leak leakage occurred at the tube / header plate junction, which was a failure (x). Moreover, the corrosion resistance of the tube was also unacceptable (x).

  In Comparative Example 6-6, since the Mn concentration of the tube was high, the extrudability was poor and the subsequent evaluation could not be performed.

  In Comparative Example 6-7, the tube was not sprayed with Zn, and thus the corrosion resistance of the tube was rejected (x).

  In Comparative Example 6-8, although the amount of Zn sprayed on the tube is small, Zn was concentrated at the tube / header plate junction, so the pitting corrosion potential at the tube / header plate junction was higher than the pitting corrosion potential at the tube / header plate. It became obscene. As a result, leak leakage occurred at the tube / header plate junction, which was a failure (x). Moreover, the corrosion resistance of the tube was also unacceptable (x).

  In Comparative Example 6-9, since the amount of Zn sprayed on the tube was large, Zn was concentrated in the tube / header plate junction, so the pitting corrosion potential of the tube / header plate junction was lower than the pitting corrosion potential of the header plate. became. As a result, leak leakage occurred at the tube / header plate junction, which was a failure (x).

  In Comparative Example 6-10, since the brazing material L2 of the tank plate had a low Si concentration, the amount of the brazing was insufficient and the brazing was poor, so that the subsequent evaluation could not be performed.

  In Comparative Example 6-11, since the Si concentration of the brazing filler metal L2 of the tank plate was high, it was cracked at the time of casting, so that subsequent evaluation could not be performed.

  In Comparative Example 6-12, since the Zn concentration in the brazing material L2 of the tank plate was high, Zn was concentrated in the header plate / tank plate junction, so that the pitting corrosion potential at the header plate / tank plate junction was It became lower than the pitting corrosion potential of the tank plate. As a result, leak leakage occurred at the header plate / tank plate junction, which was a failure (x).

  In Comparative Example 6-13, since the Si concentration of the core material of the tank plate is low, the Mn solid solution amount increases, and the pitting corrosion potential of the tank plate becomes nobler than the pitting corrosion potential of the header plate / tank plate junction. It was. As a result, leak leakage occurred at the header plate / tank plate junction, which was a failure (x). Moreover, the corrosion resistance of the tank plate was also unacceptable (x).

  In Comparative Example 6-14, since the Si concentration of the core material of the tank plate was high, it was cracked during rolling, so that subsequent evaluation could not be performed.

  In Comparative Example 6-15, since the Cu concentration in the core material of the tank plate is low, the Cu concentration in the header plate / tank plate junction is low, and the pitting potential at the header plate / tank plate junction is low. It became lower than the pitting corrosion potential. As a result, leak leakage occurred at the header plate / tank plate junction, which was a failure (x). Moreover, the corrosion resistance of the header plate was also rejected (x).

  In Comparative Example 6-16, since the Cu concentration of the core material of the tank plate was high, the tank plate locally melted during brazing, and subsequent evaluation could not be performed.

  In Comparative Example 6-17, since the Mn concentration of the core material of the tank plate is low, the amount of Si solid solution is increased, and the pitting corrosion potential of the tank plate becomes higher than the pitting corrosion potential of the header plate / tank plate junction. It was. As a result, leak leakage occurred at the header plate / tank plate junction, which was a failure (x). Moreover, the corrosion resistance of the tank plate was also unacceptable (x).

  In Comparative Example 6-18, since the Mn concentration of the core material of the tank plate was high, cracking occurred during rolling, and subsequent evaluation could not be performed.

  In Comparative Example 6-19, since the Zn concentration of the skin L4 of the header plate was high, Zn was concentrated in the tube / header plate junction, so that the pitting potential at the tube / header plate junction was It became lower than the pitting corrosion potential. As a result, leak leakage occurred at the tube / header plate junction, which was a failure (x).

  In Comparative Example 6-20, since the Si concentration of the core material of the header plate was low, the Mn solid solution amount increased, and the pitting corrosion potential of the header plate became more noble than the pitting corrosion potential of the tube / header plate junction. . As a result, leak leakage occurred at the tube / header plate junction, which was a failure (x). Furthermore, the pitting corrosion potential of the header plate became nobler than the pitting corrosion potential of the header plate / tank plate junction. As a result, leak leakage occurred at the header plate / tank plate junction, which was a failure (x). Moreover, the corrosion resistance of the header plate was also rejected (x).

  In Comparative Example 6-21, since the Si concentration of the core material of the header plate was high, cracking occurred during rolling, and subsequent evaluation could not be performed.

  In Comparative Example 6-22, since the Cu concentration of the core material of the header plate is low, the Cu concentration of the tube / header plate joint portion is low, and the pitting corrosion potential of the tube / header plate joint portion is pitting corrosion of the tube and the header plate. It became lower than potential. As a result, leak leakage occurred at the tube / header plate junction, which was a failure (x). Moreover, the corrosion resistance of the header plate was also rejected (x).

  In Comparative Example 6-23, since the Cu concentration of the core material of the header plate was high, the tank plate locally melted during brazing, and subsequent evaluation could not be performed.

  In Comparative Example 6-24, since the Mn concentration of the core material of the header plate was low, the amount of Si solid solution increased, and the pitting corrosion potential of the header plate became nobler than the pitting corrosion potential of the tube / header plate junction. . As a result, leak leakage occurred at the tube / header plate junction, which was a failure (x). Furthermore, the pitting corrosion potential of the header plate became nobler than the pitting corrosion potential of the header plate / tank plate junction. As a result, leak leakage occurred at the header plate / tank plate junction, which was a failure (x). Moreover, the corrosion resistance of the header plate was also rejected (x).

  In Comparative Example 6-25, since the Mn concentration of the core material of the header plate was high, it was cracked during rolling, so that subsequent evaluation could not be performed.

  In Comparative Example 6-26, since the Si concentration of the brazing filler metal L3 of the header plate is low, the movement of Cu to the header plate / tank plate junction is not sufficient, and the Cu concentration to the header plate / tank plate junction is low. The header plate / tank plate junction pitting potential was lower than the header plate and tank plate pitting potential. As a result, leak leakage occurred at the header plate / tank plate junction, which was a failure (x).

  In Comparative Example 6-27, since the Si concentration of the brazing filler metal L3 of the header plate was high, it was cracked during casting, so that subsequent evaluation could not be performed.

  In Comparative Example 6-28, since the Cu concentration of the brazing filler metal L3 of the header plate was high, it was cracked during casting, so that subsequent evaluation could not be performed.

  In Comparative Example 6-29, the header plate / tank plate joint was not brazed because the joint surface of the header plate and the tank plate was not brazed. As a result, leak leakage occurred at the header plate / tank plate junction, which was a failure (x).

(Invention Examples 7-1 to 7-53 and Comparative Examples 7-1 to 7-28)
Table 22 shows an example of the heat exchanger having the structure of FIG. The brazed item described in the header plate and the tank plate indicates the joint surface between the header plate and the tank plate.

  In Invention Examples 7-1 to 7-53, all the pitting corrosion potential relationships satisfied the range defined in the present invention, and therefore all the corrosion resistances were acceptable (O).

  On the other hand, in Comparative Example 7-1, since the Si concentration in the tube is low, the Mn solid solution amount increases, and the pitting corrosion potential of the tube becomes nobler than the pitting corrosion potential of the tube / header plate junction. It was. As a result, leak leakage occurred at the tube / header plate junction, which was a failure (x). Moreover, the corrosion resistance of the tube was also unacceptable (x).

  In Comparative Example 7-2, since the Si concentration of the tube was high, the extrudability was poor and subsequent evaluation could not be performed.

  In Comparative Example 7-3, since the Cu concentration of the tube is low, the Cu concentration of the tube / header plate joint is low, and the pitting corrosion potential of the tube / header plate joint is higher than the pitting corrosion potential of the tube and the header plate. I became obscene. As a result, leak leakage occurred at the tube / header plate junction, which was a failure (x). Moreover, the corrosion resistance of the tube was also unacceptable (x).

  In Comparative Example 7-4, since the Cu concentration of the tube was high, the tube was locally melted during brazing, and subsequent evaluation could not be performed.

  In Comparative Example 7-5, since the Mn concentration of the tube was low, the amount of Si solid solution was increased, and the pitting corrosion potential of the tube became nobler than the pitting corrosion potential of the tube / header plate junction. As a result, leak leakage occurred at the tube / header plate junction, which was a failure (x). Moreover, the corrosion resistance of the tube was also unacceptable (x).

  In Comparative Example 7-6, since the Mn concentration of the tube was high, the extrudability was poor and subsequent evaluation could not be performed.

  In Comparative Example 7-7, since the tube was not sprayed with Zn, the corrosion resistance of the tube was rejected (x).

  In Comparative Example 7-8, the amount of sprayed Zn on the tube is small, but the Zn / condensation potential at the tube / header plate joint is higher than the pitting corrosion potential at the tube / header plate joint because the Zn is concentrated in the tube / header plate joint It became obscene. As a result, leak leakage occurred at the tube / header plate junction, which was a failure (x). Moreover, the corrosion resistance of the tube was also unacceptable (x).

  In Comparative Example 7-9, since the amount of Zn sprayed on the tube was large, Zn was concentrated in the tube / header plate junction, so that the pitting corrosion potential of the tube / header plate junction was lower than the pitting corrosion potential of the header plate. became. As a result, leak leakage occurred at the tube / header plate junction, which was a failure (x).

  In Comparative Example 7-10, since the Si concentration of the brazing filler metal L2 of the header plate was low, the amount of the brazing was insufficient and the brazing was poor, so that the subsequent evaluation could not be performed.

  In Comparative Example 7-11, since the Si concentration of the brazing filler metal L2 of the header plate was high, it was cracked at the time of casting, so that subsequent evaluation could not be performed.

  In Comparative Example 7-12, since the Zn concentration in the brazing filler metal L2 of the header plate was high, Zn was concentrated in the tube / header plate junction, so that the pitting corrosion potential at the tube / header plate junction was It became lower than the pitting corrosion potential. As a result, leak leakage occurred at the tube / header plate junction, which was a failure (x).

  In Comparative Example 7-13, since the Si concentration of the core material of the header plate was low, the Mn solid solution amount increased, and the pitting corrosion potential of the header plate became nobler than the pitting corrosion potential of the tube / header plate junction. . As a result, leak leakage occurred at the tube / header plate junction, which was a failure (x). Furthermore, the pitting corrosion potential of the header plate became nobler than the pitting corrosion potential of the header plate / tank plate junction. As a result, leak leakage occurred at the header plate / tank plate junction, which was a failure (x). Moreover, the corrosion resistance of the header plate was also rejected (x).

  In Comparative Examples 7-14, since the Si concentration of the core material of the header plate was high, cracking occurred during rolling, and subsequent evaluation could not be performed.

  In Comparative Examples 7-15, since the Cu concentration of the core material of the header plate is low, the Cu concentration of the tube / header plate joint portion is low, and the pitting corrosion potential of the tube / header plate joint portion is pitting corrosion of the tube and the header plate. It became lower than potential. As a result, leak leakage occurred at the tube / header plate junction, which was a failure (x). Moreover, the corrosion resistance of the header plate was also rejected (x).

  In Comparative Examples 7-16, since the Cu concentration of the core material of the header plate was high, the header plate locally melted during brazing, and subsequent evaluation could not be performed.

  In Comparative Example 7-17, since the Mn concentration of the core material of the header plate was low, the amount of Si solid solution increased, and the pitting corrosion potential of the header plate became nobler than the pitting corrosion potential of the tube / header plate junction. . As a result, leak leakage occurred at the tube / header plate junction, which was a failure (x). Furthermore, the pitting corrosion potential of the header plate became nobler than the pitting corrosion potential of the header plate / tank plate junction. As a result, leak leakage occurred at the header plate / tank plate junction, which was a failure (x). Moreover, the corrosion resistance of the header plate was also rejected (x).

  In Comparative Examples 7-18, since the Mn concentration of the core material of the header plate was high, cracking occurred during rolling, and subsequent evaluation could not be performed.

  In Comparative Examples 7-19, since the brazing filler metal L1 of the header plate had a low Si concentration, the amount of brazing was insufficient and the brazing was poor, so that the subsequent evaluation could not be performed.

  In Comparative Example 7-20, since the brazing filler metal L1 of the header plate had a high Si concentration, it was cracked during casting, and subsequent evaluation could not be performed.

  In Comparative Example 7-21, since the Zn concentration of the tank plate skin L4 was high, Zn was concentrated in the header plate / tank plate junction, so the pitting corrosion potential of the header plate / tank plate junction was It became lower than the pitting corrosion potential of the tank plate. As a result, leak leakage occurred at the header plate / tank plate junction, which was a failure (x).

  In Comparative Example 7-22, since the Si concentration in the core material of the tank plate is low, the Mn solid solution amount increases, and the pitting corrosion potential of the tank plate becomes nobler than the pitting corrosion potential of the header plate / tank plate junction. It was. As a result, leak leakage occurred at the header plate / tank plate junction, which was a failure (x). Moreover, the corrosion resistance of the tank plate was also unacceptable (x).

  In Comparative Examples 7 to 23, since the Si concentration of the core material of the tank plate was high, it was cracked during rolling, so that subsequent evaluation could not be performed.

  In Comparative Example 7-24, since the Cu concentration of the core material of the tank plate is low, the Cu concentration of the tube / header plate junction is low, and the pitting corrosion potential of the header plate / tank plate junction is lower than that of the header plate and the tank plate. It became lower than the pitting corrosion potential. As a result, leak leakage occurred at the header plate / tank plate junction, which was a failure (x). Moreover, the corrosion resistance of the tank plate was also unacceptable (x).

  In Comparative Examples 7-25, since the Cu concentration of the core material of the tank plate was high, the header plate was locally melted during brazing, and subsequent evaluation could not be performed.

  In Comparative Example 7-26, since the Mn concentration of the core material of the tank plate is low, the amount of Si solid solution increases, and the pitting corrosion potential of the tank plate becomes nobler than the pitting corrosion potential of the header plate / tank plate junction. It was. As a result, leak leakage occurred at the header plate / tank plate junction, which was a failure (x). Moreover, the corrosion resistance of the tank plate was also unacceptable (x).

  In Comparative Example 7-27, since the Mn concentration of the core material of the tank plate was high, it was cracked during rolling, so that subsequent evaluation could not be performed.

  In Comparative Example 7-28, since the joint surface between the header plate and the tank plate was inappropriate, the pitting corrosion potential at the header plate / tank plate junction was lower than the pitting corrosion potential at the header plate and the tank plate. As a result, leak leakage occurred at the header plate / tank plate junction, which was a failure (x).

(Invention Examples 8-1 to 8-53 and Comparative Examples 8-1 to 8-27)
Table 23 shows an example of the heat exchanger having the structure of FIG. The brazed item described in the header plate and the tank plate indicates the joint surface between the header plate and the tank plate.

  In Invention Examples 8-1 to 8-53, all the pitting corrosion potential relationships satisfied the range defined in the present invention, and therefore all the corrosion resistances were acceptable (O).

  On the other hand, in Comparative Example 8-1, since the Si concentration of the tube is low, the Mn solid solution amount increases, and the pitting corrosion potential of the tube becomes nobler than the pitting corrosion potential of the tube / header plate junction. It was. As a result, leak leakage occurred at the tube / header plate junction, which was a failure (x). Moreover, the corrosion resistance of the tube was also unacceptable (x).

  In Comparative Example 8-2, since the Si concentration of the tube was high, the extrudability was poor and subsequent evaluation could not be performed.

  In Comparative Example 8-3, since the Cu concentration of the tube is low, the Cu concentration of the tube / header plate joint is low, and the pitting corrosion potential of the tube / header plate joint is higher than the pitting corrosion potential of the tube and the header plate. I became obscene. As a result, leak leakage occurred at the tube / header plate junction, which was a failure (x). Moreover, the corrosion resistance of the tube was also unacceptable (x).

  In Comparative Example 8-4, since the Cu concentration of the tube was high, the tube was locally melted during brazing, and subsequent evaluation could not be performed.

  In Comparative Example 8-5, since the Mn concentration of the tube was low, the amount of Si solid solution was increased, and the pitting corrosion potential of the tube became nobler than the pitting corrosion potential of the tube / header plate junction. As a result, leak leakage occurred at the tube / header plate junction, which was a failure (x). Moreover, the corrosion resistance of the tube was also unacceptable (x).

  In Comparative Example 8-6, since the Mn concentration of the tube was high, the extrudability was poor and subsequent evaluation could not be performed.

  In Comparative Example 8-7, since the Zn spraying was not performed on the tube, the corrosion resistance of the tube was rejected (x).

  In Comparative Example 8-8, the amount of Zn sprayed on the tube is small, but because Zn was concentrated in the tube / header plate junction, the pitting corrosion potential of the tube / header plate junction is higher than the pitting corrosion potential of the tube and header plate. I became obscene. As a result, leak leakage occurred at the tube / header plate junction, which was a failure (x). Moreover, the corrosion resistance of the tube was also unacceptable (x).

  In Comparative Example 8-9, since the Zn sprayed amount of the tube is large, Zn was concentrated in the tube / header plate junction, so that the pitting corrosion potential of the tube / header plate junction was lower than the pitting corrosion potential of the header plate. became. As a result, leak leakage occurred at the tube / header plate junction, which was a failure (x).

  In Comparative Example 8-10, since the brazing material L2 of the tank plate had a low Si concentration, the amount of brazing was insufficient and the brazing was poor, so that the subsequent evaluation could not be performed.

  In Comparative Example 8-11, since the Si concentration of the brazing filler metal L2 of the tank plate was high, it was cracked at the time of casting, so that subsequent evaluation could not be performed.

  In Comparative Example 8-12, since the Si concentration of the core material of the tank plate is low, the Mn solid solution amount increases, and the pitting corrosion potential of the tank plate becomes nobler than the pitting corrosion potential of the header plate / tank plate junction. It was. As a result, leak leakage occurred at the header plate / tank plate junction, which was a failure (x). Moreover, the corrosion resistance of the tank plate was also unacceptable (x).

  In Comparative Example 8-13, since the Si concentration of the core material of the tank plate was high, cracking occurred during rolling, and subsequent evaluation could not be performed.

  In Comparative Example 8-14, since the Cu concentration in the core material of the tank plate is low, the Cu concentration in the header plate / tank plate junction is low, and the pitting potential at the header plate / tank plate junction is low. It became lower than the pitting corrosion potential. As a result, leak leakage occurred at the header plate / tank plate junction, which was a failure (x). Moreover, the corrosion resistance of the tank plate was also unacceptable (x).

  In Comparative Examples 8-15, since the Cu concentration of the core material of the tank plate was high, the tank plate was locally melted during brazing, and subsequent evaluation could not be performed.

  In Comparative Example 8-16, since the Mn concentration of the core material of the tank plate is low, the amount of Si solid solution increases, and the pitting corrosion potential of the tank plate becomes nobler than the pitting corrosion potential of the header plate / tank plate junction. It was. As a result, leak leakage occurred at the header plate / tank plate junction, which was a failure (x). Moreover, the corrosion resistance of the tank plate was also unacceptable (x).

  In Comparative Example 8-17, since the Mn concentration of the core material of the tank plate was high, cracking occurred during rolling, and subsequent evaluation could not be performed.

  In Comparative Example 8-18, since the brazing filler metal L1 of the header plate had a low Si concentration, the amount of brazing was insufficient and the brazing was poor, so that the subsequent evaluation could not be performed.

  In Comparative Example 8-19, since the Si concentration of the brazing filler metal L1 of the header plate was high, it was cracked at the time of casting, so that subsequent evaluation could not be performed.

  In Comparative Example 8-20, since the Zn concentration of the skin L4 of the header plate was high, Zn was concentrated in the tube / header plate junction, so the pitting corrosion potential of the tube / header plate junction was It became lower than the pitting corrosion potential. As a result, leak leakage occurred at the tube / header plate junction, which was a failure (x). Furthermore, since Zn was concentrated in the header plate / tank plate junction, the pitting corrosion potential of the header plate / tank plate junction became lower than the pitting corrosion potential of the header plate and the tank plate. As a result, leak leakage occurred at the header plate / tank plate junction, which was a failure (x).

  In Comparative Example 8-21, since the Si concentration of the core material of the header plate was low, the Mn solid solution amount increased, and the pitting corrosion potential of the header plate became nobler than the pitting corrosion potential of the tube / header plate junction. . As a result, leak leakage occurred at the tube / header plate junction, which was a failure (x). Furthermore, the pitting corrosion potential of the header plate became nobler than the pitting corrosion potential of the header plate / tank plate junction. As a result, leak leakage occurred at the header plate / tank plate junction, which was a failure (x). Moreover, the corrosion resistance of the header plate was also rejected (x).

  In Comparative Example 8-22, since the Si concentration of the core material of the header plate was high, it was cracked during rolling, so that subsequent evaluation could not be performed.

  In Comparative Example 8-23, since the Cu concentration of the core material of the header plate is low, the Cu concentration of the tube / header plate joint portion is low, and the pitting corrosion potential of the tube / header plate joint portion is pitting corrosion of the tube and the header plate. It became lower than potential. As a result, leak leakage occurred at the tube / header plate junction, which was a failure (x). Moreover, the corrosion resistance of the header plate was also rejected (x).

  In Comparative Example 8-24, since the Cu concentration of the core material of the header plate was high, the header plate locally melted during brazing, and subsequent evaluation could not be performed.

  In Comparative Example 8-25, since the Mn concentration of the core material of the header plate was low, the amount of Si solid solution increased, and the pitting corrosion potential of the header plate became nobler than the pitting corrosion potential of the tube / header plate junction. . As a result, leak leakage occurred at the tube / header plate junction, which was a failure (x). Furthermore, the pitting corrosion potential of the header plate became nobler than the pitting corrosion potential of the header plate / tank plate junction. As a result, leak leakage occurred at the header plate / tank plate junction, which was a failure (x). Moreover, the corrosion resistance of the header plate was also rejected (x).

  In Comparative Example 8-26, since the Mn concentration of the core material of the header plate was high, cracking occurred during rolling, and subsequent evaluation could not be performed.

  In Comparative Example 8-27, the joint surface between the header plate and the tank plate was unsuitable, so the pitting corrosion potential at the header plate / tank plate junction was lower than the pitting corrosion potential at the header plate and the tank plate. As a result, leak leakage occurred at the header plate / tank plate junction, which was a failure (x).

(Invention Examples 9-1 to 9-55 and Comparative Examples 9-1 to 9-29)
Table 24 shows an example of the heat exchanger having the structure of FIG. The brazed item described in the header plate and the tank plate indicates the joint surface between the header plate and the tank plate.

  In Invention Examples 9-1 to 9-55, all the pitting corrosion potential relations satisfied the range defined in the present invention, and thus all the corrosion resistances were acceptable (O).

  On the other hand, in Comparative Example 9-1, since the Si concentration of the tube is low, the Mn solid solution amount increases, and the pitting corrosion potential of the tube becomes nobler than the pitting corrosion potential of the tube / header plate junction. It was. As a result, leak leakage occurred at the tube / header plate junction, which was a failure (x). Moreover, the corrosion resistance of the tube was also unacceptable (x).

  In Comparative Example 9-2, since the Si concentration of the tube was high, the extrudability was poor and subsequent evaluation could not be performed.

  In Comparative Example 9-3, since the Cu concentration of the tube is low, the Cu concentration of the tube / header plate joint is low, and the pitting corrosion potential of the tube / header plate joint is higher than the pitting corrosion potential of the tube and the header plate. I became obscene. As a result, leak leakage occurred at the tube / header plate junction, which was a failure (x). Moreover, the corrosion resistance of the tube was also unacceptable (x).

  In Comparative Example 9-4, since the Cu concentration of the tube was high, the tube locally melted during brazing, and subsequent evaluation could not be performed.

  In Comparative Example 9-5, since the Mn concentration in the tube was low, the amount of Si solid solution increased, and the pitting corrosion potential of the tube became more noble than the pitting corrosion potential of the tube / header plate junction. As a result, leak leakage occurred at the tube / header plate junction, which was a failure (x). Moreover, the corrosion resistance of the tube was also unacceptable (x).

  In Comparative Example 9-6, since the Mn concentration of the tube was high, the extrudability was poor and the subsequent evaluation could not be performed.

  In Comparative Example 9-7, since the tube was not sprayed with Zn, the corrosion resistance of the tube was rejected (x).

  In Comparative Example 9-8, although the amount of Zn sprayed on the tube is small, Zn was concentrated at the tube / header plate junction, so the pitting corrosion potential at the tube / header plate junction was higher than the pitting corrosion potential at the tube / header plate. I became obscene. As a result, leak leakage occurred at the tube / header plate junction, which was a failure (x). Moreover, the corrosion resistance of the tube was also unacceptable (x).

  In Comparative Example 9-9, because the amount of Zn sprayed on the tube was large, Zn was concentrated at the tube / header plate junction, so the pitting corrosion potential at the tube / header plate junction was lower than the pitting corrosion potential at the header plate. became. As a result, leak leakage occurred at the tube / header plate junction, which was a failure (x).

  In Comparative Example 9-10, since the Zn concentration in the skin material L4 of the header plate was high, Zn was concentrated in the tube / header plate junction, so that the pitting potential at the tube / header plate junction was It became lower than the pitting corrosion potential. As a result, leak leakage occurred at the tube / header plate junction, which was a failure (x).

  In Comparative Example 9-11, since the Si concentration in the core material of the header plate was low, the Mn solid solution amount increased, and the pitting corrosion potential of the header plate became nobler than the pitting corrosion potential of the tube / header plate junction. . As a result, leak leakage occurred at the tube / header plate junction, which was a failure (x). Furthermore, the pitting corrosion potential of the header plate became nobler than the pitting corrosion potential of the header plate / tank plate junction. As a result, leak leakage occurred at the header plate / tank plate junction, which was a failure (x). Moreover, the corrosion resistance of the header plate was also rejected (x).

  In Comparative Examples 9-12, since the Si concentration of the core material of the header plate was high, it was cracked during rolling, so that subsequent evaluation could not be performed.

  In Comparative Example 9-13, since the Cu concentration of the core material of the header plate is low, the Cu concentration of the tube / header plate joint portion is low, and the pitting corrosion potential of the tube / header plate joint portion is pitting corrosion of the tube and the header plate. It became lower than potential. As a result, leak leakage occurred at the tube / header plate junction, which was a failure (x). Moreover, the corrosion resistance of the header plate was also rejected (x).

  In Comparative Examples 9-14, since the Cu concentration of the core material of the header plate was high, the tank plate locally melted during brazing, and subsequent evaluation could not be performed.

  In Comparative Example 9-15, since the Mn concentration of the core material of the header plate was low, the amount of Si solid solution increased, and the pitting corrosion potential of the header plate became nobler than the pitting corrosion potential of the tube / header plate junction. . As a result, leak leakage occurred at the tube / header plate junction, which was a failure (x). Furthermore, the pitting corrosion potential of the header plate became nobler than the pitting corrosion potential of the header plate / tank plate junction. As a result, leak leakage occurred at the header plate / tank plate junction, which was a failure (x). Moreover, the corrosion resistance of the header plate was also rejected (x).

  In Comparative Example 9-16, since the Mn concentration of the core material of the header plate was high, cracking occurred during rolling, and subsequent evaluation could not be performed.

  In Comparative Example 9-17, since the Si concentration of the brazing filler metal L3 of the header plate is low, the movement of Cu to the header plate / tank plate junction is not sufficient, and the Cu concentration to the header plate / tank plate junction is low. The header plate / tank plate junction pitting potential was lower than the header plate and tank plate pitting potential. As a result, leak leakage occurred at the header plate / tank plate junction, which was a failure (x).

  In Comparative Example 9-18, since the Si concentration of the brazing filler metal L3 of the header plate was high, it was cracked at the time of casting, so that subsequent evaluation could not be performed.

  In Comparative Example 9-19, since the Cu concentration of the brazing filler metal L3 of the header plate was high, it was cracked at the time of casting, so that subsequent evaluation could not be performed.

  In Comparative Example 9-20, since the Si concentration of the brazing material L1 of the tank plate was low, the amount of the brazing was insufficient and the brazing was poor, so that the subsequent evaluation could not be performed.

  In Comparative Example 9-21, since the Si concentration of the brazing filler metal L1 of the tank plate was high, it was cracked at the time of casting, so that subsequent evaluation could not be performed.

  In Comparative Example 9-22, since the Zn concentration in the tank plate skin L4 was high, Zn was concentrated in the header plate / tank plate junction, so the pitting potential at the header plate / tank plate junction was It became lower than the pitting corrosion potential of the tank plate. As a result, leak leakage occurred at the header plate / tank plate junction, which was a failure (x).

  In Comparative Example 9-23, since the Si concentration of the core material of the tank plate is low, the Mn solid solution amount increases, and the pitting corrosion potential of the tank plate becomes nobler than the pitting corrosion potential of the header plate / tank plate junction. It was. As a result, leak leakage occurred at the header plate / tank plate junction, which was a failure (x). Moreover, the corrosion resistance of the tank plate was also unacceptable (x).

  In Comparative Example 9-24, since the Si concentration of the core material of the tank plate was high, it was cracked during rolling, and subsequent evaluation could not be performed.

  In Comparative Example 9-25, since the Cu concentration of the core material of the tank plate is low, the Cu concentration of the tube / header plate junction is low, and the pitting corrosion potential of the header plate / tank plate junction is low between the header plate and the tank plate. It became lower than the pitting corrosion potential. As a result, leak leakage occurred at the header plate / tank plate junction, which was a failure (x). Moreover, the corrosion resistance of the tank plate was also unacceptable (x).

  In Comparative Example 9-26, since the Cu concentration of the core material of the tank plate was high, the header plate locally melted during brazing, and subsequent evaluation could not be performed.

  In Comparative Example 9-27, since the Mn concentration of the core material of the tank plate is low, the amount of Si solid solution increases, and the pitting corrosion potential of the tank plate becomes nobler than the pitting corrosion potential of the header plate / tank plate junction. It was. As a result, leak leakage occurred at the header plate / tank plate junction, which was a failure (x). Moreover, the corrosion resistance of the tank plate was also unacceptable (x).

  In Comparative Example 9-28, since the Mn concentration of the core material of the tank plate was high, cracking occurred during rolling, and subsequent evaluation could not be performed.

  In Comparative Examples 9-29, the header plate / tank plate joint was not brazed because the joint surface of the header plate and the tank plate was not brazed. As a result, leak leakage occurred at the header plate / tank plate junction, which was a failure (x).

(Invention Examples 10-1 to 10-55 and Comparative Examples 10-1 to 10-27)
Table 25 shows examples of the heat exchanger having the structure shown in FIG. The brazed item described in the header plate and the tank plate indicates the joint surface between the header plate and the tank plate.

  In Invention Examples 10-1 to 10-55, all the pitting corrosion potential relationships satisfied the range defined in the present invention, and therefore all the corrosion resistances were acceptable (O).

  On the other hand, in Comparative Example 10-1, since the Si concentration of the tube is low, the Mn solid solution amount increases, and the pitting corrosion potential of the tube becomes nobler than the pitting corrosion potential of the tube / header plate junction. It was. As a result, leak leakage occurred at the tube / header plate junction, which was a failure (x). Moreover, the corrosion resistance of the tube was also unacceptable (x).

  In Comparative Example 10-2, since the Si concentration of the tube was high, the extrudability was poor and subsequent evaluation could not be performed.

  In Comparative Example 10-3, since the Cu concentration of the tube is low, the Cu concentration of the tube / header plate joint is low, and the pitting corrosion potential of the tube / header plate joint is higher than the pitting corrosion potential of the tube and the header plate. I became obscene. As a result, leak leakage occurred at the tube / header plate junction, which was a failure (x). Moreover, the corrosion resistance of the tube was also unacceptable (x).

  In Comparative Example 10-4, since the Cu concentration of the tube was high, the tube was locally melted during brazing, and subsequent evaluation could not be performed.

  In Comparative Example 10-5, since the Mn concentration in the tube was low, the amount of Si solid solution increased, and the pitting corrosion potential of the tube became nobler than the pitting corrosion potential of the tube / header plate junction. As a result, leak leakage occurred at the tube / header plate junction, which was a failure (x). Moreover, the corrosion resistance of the tube was also unacceptable (x).

  In Comparative Example 10-6, since the Mn concentration of the tube was high, the extrudability was poor and subsequent evaluation could not be performed.

  In Comparative Example 10-7, since the tube was not sprayed with Zn, the corrosion resistance of the tube was rejected (x).

  In Comparative Example 10-8, the amount of Zn sprayed on the tube is small, but since the Zn was concentrated in the tube / header plate junction, the pitting corrosion potential of the tube / header plate junction is higher than the pitting corrosion potential of the tube and header plate. I became obscene. As a result, leak leakage occurred at the tube / header plate junction, which was a failure (x). Moreover, the corrosion resistance of the tube was also unacceptable (x).

  In Comparative Example 10-9, because the amount of Zn sprayed on the tube was large, Zn was concentrated at the tube / header plate junction, so the pitting corrosion potential at the tube / header plate junction was lower than that at the header plate. became. As a result, leak leakage occurred at the tube / header plate junction, which was a failure (x).

  In Comparative Example 10-10, since the Si concentration of the core material of the tank plate is low, the Mn solid solution amount increases, and the pitting corrosion potential of the tank plate becomes nobler than the pitting corrosion potential of the header plate / tank plate junction. It was. As a result, leak leakage occurred at the header plate / tank plate junction, which was a failure (x). Moreover, the corrosion resistance of the tank plate was also unacceptable (x).

  In Comparative Example 10-11, since the Si concentration of the core material of the tank plate was high, cracking occurred during rolling, and subsequent evaluation could not be performed.

  In Comparative Examples 10-12, since the Cu concentration of the core material of the tank plate was high, the tank plate locally melted during brazing, and subsequent evaluation could not be performed.

  In Comparative Example 10-13, since the Mn concentration of the core material of the tank plate is low, the amount of Si solid solution increases, and the pitting corrosion potential of the tank plate becomes nobler than the pitting corrosion potential of the header plate / tank plate junction. It was. As a result, leak leakage occurred at the header plate / tank plate junction, which was a failure (x). Moreover, the corrosion resistance of the tank plate was also unacceptable (x).

  In Comparative Example 10-14, since the Mn concentration of the core material of the tank plate was high, it was cracked during rolling, and subsequent evaluation could not be performed.

  In Comparative Example 10-15, since the Si concentration of the brazing filler metal L3 of the tank plate is low, the movement of Cu to the header plate / tank plate junction is not sufficient, and the Cu concentration to the header plate / tank plate junction is low. The header plate / tank plate junction pitting potential was lower than the header plate and tank plate pitting potential. As a result, leak leakage occurred at the header plate / tank plate junction, which was a failure (x).

  In Comparative Example 10-16, since the Si concentration of the brazing filler metal L3 of the tank plate was high, it was cracked at the time of casting, so that subsequent evaluation could not be performed.

  In Comparative Example 10-17, since the Cu concentration of the brazing material L3 of the tank plate was high, it was cracked at the time of casting, so that subsequent evaluation could not be performed.

  In Comparative Example 10-18, since the brazing filler metal L1 of the header plate had a low Si concentration, the amount of brazing was insufficient and the brazing was poor, so that the subsequent evaluation could not be performed.

  In Comparative Example 10-19, since the brazing filler metal L1 of the header plate had a high Si concentration, it was cracked at the time of casting, so that subsequent evaluation could not be performed.

  In Comparative Example 10-20, since the Zn concentration of the skin material L4 of the header plate was high, Zn was concentrated in the tube / header plate junction, so that the pitting corrosion potential of the tube / header plate junction was It became lower than the pitting corrosion potential. As a result, leak leakage occurred at the tube / header plate junction, which was a failure (x). Furthermore, since Zn was concentrated in the header plate / tank plate junction, the pitting corrosion potential of the header plate / tank plate junction became lower than the pitting corrosion potential of the header plate and the tank plate. As a result, leak leakage occurred at the header plate / tank plate junction, which was a failure (x).

  In Comparative Example 10-21, since the Si concentration of the core material of the header plate was low, the Mn solid solution amount increased, and the pitting corrosion potential of the header plate became nobler than the pitting corrosion potential of the tube / header plate junction. . As a result, leak leakage occurred at the tube / header plate junction, which was a failure (x). Furthermore, the pitting corrosion potential of the header plate became nobler than the pitting corrosion potential of the header plate / tank plate junction. As a result, leak leakage occurred at the header plate / tank plate junction, which was a failure (x). Moreover, the corrosion resistance of the header plate was also rejected (x).

  In Comparative Example 10-22, since the Si concentration of the core material of the header plate was high, cracking occurred during rolling, and subsequent evaluation could not be performed.

  In Comparative Example 10-23, since the Cu concentration of the core material of the header plate is low, the Cu concentration of the tube / header plate joint portion is low, and the pitting corrosion potential of the tube / header plate joint portion is pitting corrosion of the tube and the header plate. It became lower than potential. As a result, leak leakage occurred at the tube / header plate junction, which was a failure (x). Moreover, the corrosion resistance of the header plate was also rejected (x).

  In Comparative Examples 10-24, since the Cu concentration of the core material of the header plate was high, the header plate locally melted during brazing, and subsequent evaluation could not be performed.

  In Comparative Example 10-25, since the Mn concentration of the core material of the header plate was low, the amount of Si solid solution increased, and the pitting corrosion potential of the header plate became nobler than the pitting corrosion potential of the tube / header plate junction. . As a result, leak leakage occurred at the tube / header plate junction, which was a failure (x). Furthermore, the pitting corrosion potential of the header plate became nobler than the pitting corrosion potential of the header plate / tank plate junction. As a result, leak leakage occurred at the header plate / tank plate junction, which was a failure (x). Moreover, the corrosion resistance of the header plate was also rejected (x).

  In Comparative Example 10-26, since the Mn concentration of the core material of the header plate was high, it was cracked during rolling, and subsequent evaluation could not be performed.

  In Comparative Example 10-27, the header plate / tank plate joint was not brazed because the joint surface of the header plate and the tank plate was not brazed. As a result, leak leakage occurred at the header plate / tank plate junction, which was a failure (x).

(Invention Examples 11-1 to 11-9 and Comparative Examples 11-1 to 11-8)
Table 26 shows an example of the heat exchanger having the structure shown in FIG. The brazed item described in the header plate and the tank plate indicates the joint surface between the header plate and the tank plate.

  In Invention Examples 11-1 to 11-9, since the fins satisfied the range defined in the present invention, the corrosion resistance was all acceptable (O).

  On the other hand, in Comparative Example 11-1, the strength of the fin was low because the Si concentration of the core material of the fin was low.

  In Comparative Example 11-2, since the Si concentration of the core material of the fin was high, cracking occurred during rolling, and subsequent evaluation could not be performed.

  In Comparative Example 11-3, the strength of the fin was low because the Mn concentration of the core material of the fin was low.

  In Comparative Example 11-4, since the Mn concentration of the core material of the fin was high, cracking occurred during rolling, and subsequent evaluation could not be performed.

  In Comparative Example 11-5, since the Zn concentration in the core material of the fin was low, the corrosion of the tube was promoted, and the corrosion resistance of the tube was rejected (x).

  In Comparative Example 11-6, since the Zn concentration in the fin core material was high, the corrosion of the fin was promoted, and the corrosion resistance of the fin was rejected (x).

  In Comparative Example 11-7, since the Si concentration of the fin brazing material was low, the amount of brazing was insufficient and the brazing was poor, so that the subsequent evaluation could not be performed.

  In Comparative Example 11-8, since the Si concentration of the fin brazing filler metal was high, it was cracked during casting, and subsequent evaluation could not be performed.

  As mentioned above, although embodiment of this invention was described, this embodiment is shown as an example and is not intending limiting the range of invention. This embodiment can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the spirit of the invention. This embodiment and its modifications are included in the scope of the present invention and the gist thereof, and are also included in the invention described in the claims and the equivalent scope thereof.

DESCRIPTION OF SYMBOLS 1 ... Aluminum alloy heat exchanger 2 ... Tube 3 ... Fin 4, 4A, 4B ... Header plate 5, 5A, 5B ... Tank plate 6 ... Medium path 7 ... Joining part 8 ... Joining part

Claims (8)

A plurality of tubes having fluid passages therein are arranged in parallel, and corrugated fins are sandwiched between adjacent tubes and joined together, and header plates are integrated by brazing joints at both ends of the tubes. In addition, a heat exchanger in which a tank plate is brazed and joined adjacent to the header plate to form a hollow medium passage inside.
The pitting corrosion potential at the junction between the tube and the header plate is the lowest pitting corrosion potential in the thickness direction of the tube and the lowest pitting corrosion potential in the thickness direction of the header plate. Are both noble than the pitting potential of the
And the pitting corrosion potential of the part where the pitting corrosion potential of the joint part of the header plate and the tank plate is the lowest in the thickness direction of the header plate and the pitting corrosion potential in the thickness direction of the tank plate Which is more noble than both the pitting potential of the lowest part of
The tube contains Si: 0.05 to 0.5 mass% (hereinafter referred to as%), Cu: 0.1 to 0.8%, Mn: 0.05 to 0.5%, and the balance Al and An aluminum alloy heat exchanger comprising an Al alloy material in which 3 to 15 g / m ² of Zn is provided on an Al alloy surface made of inevitable impurities. One of the header plate and the tank plate is made from a first two-layer brazing sheet made of a core material and an Al-Si alloy brazing material formed on the outside thereof, and the other is formed on the core material and the outside thereof. Produced from a second two-layer brazing sheet comprising an Al—Si—Zn alloy brazing material,
The joining of the header plate and the tank plate brings the Al—Si alloy brazing material surface of the first two-layer brazing sheet into contact with the core material surface of the second two-layer brazing sheet, Made by attaching and
The core material of the first and second two-layer brazing sheets contains Si: 0.05 to 1.0%, Cu: 0.05 to 1.0%, Mn: 0.5 to 2.0% And the balance Al and inevitable impurities,
The Al—Si based alloy brazing material of the first two-layer brazing sheet contains Si: 3.0 to 12.0%, and consists of the balance Al and inevitable impurities,
The Al—Si—Zn-based alloy brazing material of the second two-layer brazing sheet contains Si: 3.0 to 12.0%, Zn: 0 to 3.0%, and from the remaining Al and inevitable impurities. The aluminum alloy heat exchanger according to claim 1, wherein the heat exchanger is made of aluminum alloy. One of the header plate and the tank plate is manufactured from a second two-layer brazing sheet made of a core material and an Al-Si-Zn alloy brazing material formed on the outside thereof, and the other is formed on the core material and the inside thereof. It was produced from a first three-layer brazing sheet comprising an Al-Si-Cu-based alloy brazing material formed and an Al-Si-Zn-based alloy brazing material formed outside the core material,
The header plate and the tank plate are joined by the Al—Si—Zn alloy brazing material surface of the second two-layer brazing sheet and the Al—Si—Cu system of the first three-layer brazing sheet. Made by bringing the brazing alloy surface into contact and brazing,
The core material of the second two-layer brazing sheet and the first three-layer brazing sheet is Si: 0.05 to 1.0%, Cu: 0.05 to 1.0%, Mn: 0.5 to 2 0.0%, consisting of the balance Al and inevitable impurities,
The Al—Si—Cu-based alloy brazing material of the first three-layer brazing sheet contains Si: 3.0 to 12.0%, Cu: 0 to 1.0%, and consists of the balance Al and inevitable impurities. ,
The Al-Si-Zn-based alloy brazing material of the first three-layer brazing sheet contains Si: 3.0 to 12.0%, Zn: 0 to 3.0%, and consists of the balance Al and inevitable impurities. ,
The Al—Si—Zn-based alloy brazing material of the second two-layer brazing sheet contains Si: 3.0 to 12.0%, Zn: 0 to 3.0%, and consists of the balance Al and inevitable impurities. The aluminum alloy heat exchanger according to claim 1. One of the header plate and the tank plate is manufactured from a second two-layer brazing sheet made of a core material and an Al-Si-Zn alloy brazing material formed on the outside thereof, and the other is formed on the core material and the inside thereof. It was produced from a second three-layer brazing sheet comprising an Al—Si—Cu alloy brazing material formed and an Al—Zn alloy brazing material formed on the outside of the core material,
The header plate and the tank plate are joined by the Al—Si—Zn alloy brazing material surface of the second two-layer brazing sheet and the Al—Si—Cu system of the second three-layer brazing sheet. Made by bringing the brazing alloy surface into contact and brazing,
The core material of the second two-layer brazing sheet and the second three-layer brazing sheet is Si: 0.05 to 1.0%, Cu: 0.05 to 1.0%, Mn: 0.5 to Containing 2.0%, consisting of the balance Al and inevitable impurities,
The Al—Si—Cu-based alloy brazing material of the second three-layer brazing sheet contains Si: 3.0 to 12.0%, Cu: 0 to 1.0%, and consists of the balance Al and inevitable impurities. ,
The Al-Zn alloy brazing material of the second three-layer brazing sheet contains Zn: 0 to 3.0%, and consists of the balance Al and inevitable impurities,
The Al—Si—Zn-based alloy brazing material of the second two-layer brazing sheet contains Si: 3.0 to 12.0%, Zn: 0 to 3.0%, and consists of the balance Al and inevitable impurities. The aluminum alloy heat exchanger according to claim 1. One of the header plate and the tank plate is prepared from a second two-layer brazing sheet made of a core material and an Al-Si-Zn alloy brazing material formed on the outer side thereof, and the other is formed on the core material and the outer side thereof. It was produced from a third three-layer brazing sheet consisting of the formed Al-Zn alloy skin material and an Al-Si-based alloy brazing material formed on the outer side,
The header plate and the tank plate are joined by the core surface of the second two-layer brazing sheet, the Al—Zn alloy skin material of the third three-layer brazing sheet, and the Al—Si alloy brazing. Made by contacting the material surface and brazing,
The core materials of the third three-layer brazing sheet and the second two-layer brazing sheet are Si: 0.05-1.0%, Cu: 0.05-1.0%, Mn: 0.5-2 0.0%, consisting of the balance Al and inevitable impurities,
The Al-Zn alloy skin material of the third three-layer brazing sheet contains Zn: 0 to 3.0%, and consists of the balance Al and inevitable impurities,
The Al-Si-based alloy brazing material of the third three-layer brazing sheet contains Si: 3.0 to 12.0%, and consists of the balance Al and inevitable impurities,
The Al—Si—Zn-based alloy brazing material of the second two-layer brazing sheet contains Si: 3.0 to 12.0%, Zn: 0 to 3.0%, and consists of the balance Al and inevitable impurities. The aluminum alloy heat exchanger according to claim 1. One of the header plate and the tank plate is composed of a core material, an Al—Si—Cu alloy brazing material formed inside the core material, and an Al—Zn alloy brazing material formed outside the core material. Fabricated from a layer brazing sheet, the other fabricated from a third three-layer brazing sheet consisting of a core material, an Al—Zn alloy skin formed on the outside thereof, and an Al—Si based alloy brazing material formed on the outside thereof And
The header plate and the tank plate are joined by the Al—Si—Cu alloy brazing material surface of the second three-layer brazing sheet and the Al—Zn alloy skin material of the third three-layer brazing sheet. And the Al-Si alloy brazing material surface is brought into contact with each other and brazed and joined,
The core materials of the second three-layer brazing sheet and the third three-layer brazing sheet are Si: 0.05-1.0%, Cu: 0.05-1.0%, Mn: 0.5-2 0.0%, consisting of the balance Al and inevitable impurities,
The Al-Zn alloy skin material of the third three-layer brazing sheet contains Zn: 0 to 3.0%, and consists of the balance Al and inevitable impurities,
The Al-Si-based alloy brazing material of the third three-layer brazing sheet contains Si: 3.0 to 12.0%, and consists of the balance Al and inevitable impurities,
The Al—Si—Cu-based alloy brazing material of the second three-layer brazing sheet contains Si: 3.0 to 12.0%, Cu: 0 to 1.0%, and consists of the balance Al and inevitable impurities. ,
2. The aluminum alloy heat according to claim 1, wherein the Al—Zn alloy brazing material of the second three-layer brazing sheet contains Zn: 0 to 3.0%, and consists of the balance Al and inevitable impurities. Exchanger.   In the core material of the brazing sheet, Ti: 0.05 to 0.30%, Zr: 0.05 to 0.30%, Cr: 0.05 to 0.30% and V: 0.05 to 0.30 The aluminum alloy heat exchanger according to any one of claims 2 to 6, further comprising at least one selected from the group consisting of%.   An Al alloy in which the fin material contains Si: 0.05 to 1.0%, Mn: 0.5 to 2.0%, Zn: 0.5 to 4.0%, and the balance Al and inevitable impurities 8. An aluminum alloy clad material comprising an Al—Si alloy brazing material containing Si: 3.0 to 12.0% and the balance of Al and inevitable impurities on both sides of the aluminum alloy clad material. An aluminum alloy heat exchanger according to any one of the above.