JP2017226880A - Aluminum alloy-made heat exchanger excellent in corrosion resistance in air environment and manufacturing method of aluminum alloy-made heat exchanger - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an aluminum alloy-made heat exchange manufactured by blazing conjugating a fin consisting of an aluminum alloy-made blazing sheet and an aluminum alloy-made tube having a Zn anticorrosive layer, and excellent in corrosion resistance in air environment.SOLUTION: Potential difference between a blazing material and a fillet is controlled within a specified range by depositing a Si-based deposition with a specified size in a remaining blazing material or diffusing Zn of the filet with conducting further a heat treatment on a heat exchanger after blazing. Because preferential corrosion of the fillet is suppressed thereby, fin detachment is not generated and durability to corrosion is enhanced by extending time that the fin acts to a tube as a sacrificial anode material.SELECTED DRAWING: None

Description

  The present invention relates to a heat exchanger made of an aluminum alloy that has excellent durability against corrosion in an atmospheric environment and is useful for an outdoor unit and the like, and a method for manufacturing the same.

  As a heat exchanger for an outdoor unit of an air conditioner, a heat exchanger in which a copper alloy tube is combined with a fin made of an aluminum alloy and joined is conventionally used. However, in recent years, since the price of copper tends to rise, there is an increasing demand for an aluminum alloy heat exchanger in which an aluminum alloy tube and an aluminum alloy fin are combined for cost reduction.

  Aluminum alloys have many advantages such as being lightweight and excellent in thermal conductivity, being able to achieve high corrosion resistance by appropriate treatment, and being able to be joined efficiently by brazing using a brazing sheet. . For this reason, aluminum alloys have been heavily used as heat exchanger materials for automobiles and the like. These advantages are also useful as a heat exchanger material for an outdoor unit of an air conditioner. Here, as a form of such an outdoor unit heat exchanger, a combination of an aluminum alloy tube and an aluminum alloy external fin formed by molding a brazing sheet clad with brazing material on at least one surface of a core material A heat exchanger joined by brazing is currently used. In addition, as an aluminum alloy tube, an extruded flat tube manufactured by extrusion and having a flat shape is often used.

  In an aluminum alloy heat exchanger, the aluminum alloy tube is for the purpose of circulating a fluid such as a refrigerant. Therefore, an anticorrosion technique for suppressing pitting corrosion is applied so that leakage due to pitting corrosion does not occur in the tube. As this anticorrosion technique, there is a technique in which the fin is caused to act as a sacrificial anode material to the tube so that corrosion of the tube is suppressed by containing Zn in the fin. In addition to this method, there is a method of preventing the generation of through holes in the tube for a long period of time by applying Zn to the outer surface of the tube and acting as a sacrificial anode material on the tube.

  However, the tube anticorrosion technique as described above is not without problems. That is, the above anticorrosion technique assumes that the fin functions as a sacrificial anode material, but there is a problem that this function may be lost. As a cause of this problem, when the tube and the fin are brazed, Zn is concentrated in the fillet formed between the tube and the fin, and the potential of the fillet is reduced. When the potential of the fillet is reduced, preferential corrosion of the fillet occurs in the early stage of corrosion, and the connection between the tube and the fin is broken. As a result, the function of the fin as a sacrificial anode material is lost. And if a fin loses the function as a sacrificial anode material, corrosion of a tube will advance and the time until penetration will be shortened.

  In view of this problem, various methods for improving the corrosion resistance of the heat exchanger have been studied. As the method, an attempt has been made to reheat the heat exchanger after completion of brazing addition heat to control the potential configuration of the tubes and fins. For example, in Patent Document 1, a tube material made of an aluminum alloy whose surface is clad with a sacrificial anode material containing Zn is brazed with a fin material whose surface of a core material containing Zn is clad with an Al-based brazing material containing Si. A technique is disclosed in which a heat exchanger having excellent corrosion resistance is manufactured by performing heat treatment at 230 ° C. for 50 hours after brazing. Patent Document 2 discloses that an Al—Zn-based fin material is joined by brazing to an aluminum alloy tube material containing Zn and Si on the surface and clad with a sacrificial anode material having brazing properties. It discloses a technique for manufacturing a heat exchanger having excellent corrosion resistance by performing heat treatment at 230 ° C. for 50 hours after attaching.

JP 2014-178101 A JP 2014-177694 A

  In the techniques of these patent documents, the corrosion resistance of the heat exchanger is improved by performing control without changing the potential configuration of the tube and the fin by heat treatment after brazing. In addition, after the heat treatment is performed, even if the heat exchanger is heated, there is no influence on the potential configuration, so that it has corrosion resistance when used at high temperatures. However, according to the present inventors, these prior arts are insufficient to improve the corrosion resistance of the heat exchanger in the atmospheric environment.

  The present invention has been made based on the background as described above, and it is an object of the present invention to provide an aluminum alloy heat exchanger that is excellent in corrosion resistance in an atmospheric environment and used for an outdoor unit. In this problem, in particular, it was decided to improve the durability of the heat exchanger by suppressing the preferential corrosion of the fillet. Moreover, in this invention, the method of manufacturing efficiently the heat exchanger for outdoor units made from aluminum alloy excellent in such corrosion resistance is also provided.

  In order to solve the above-mentioned problems, the inventors of the present invention are formed by brazing a fin made of a brazing sheet obtained by clad an Al-Si alloy brazing material to an aluminum alloy core material containing Zn and an aluminum alloy tube. For the heat exchanger, the potential control of the fillet formed at the junction between the fin and the tube was more strictly performed. In other words, the pre-corrosion of the fillet is suppressed by bringing the potential of the fin close to that of the fillet, and the time for the fin to act as a sacrificial anode material is lengthened, thereby improving the corrosion resistance of the heat exchanger in the atmospheric environment. It was. Here, the inventors of the present invention have come up with the idea of controlling the corrosion resistance and potential of the fin by controlling the material structure of the residual brazing filler metal remaining on the fin surface as a technique for controlling the potential of the fin and fillet. In addition to controlling the material structure of the residual brazing filler metal, the inventors have also conceived of controlling the fillet potential by diffusing Zn in the fillet.

  Therefore, the present inventors have further investigated the brazing condition between the fin and the tube and the heat treatment condition after brazing in order to suitably control the structure of the residual brazing material and diffuse Zn in the fillet. It was. As a result, it has been found that the cooling rate after fin brazing is controlled, and that heat treatment after completion of brazing is performed at a temperature higher than 230 ° C., which is the prior art. And it discovered that the heat exchanger with which the electric potential structure of a fin and a fillet was optimized can be obtained combining these methods suitably. The present invention has been made based on this finding.

The first heat exchanger of the present invention that solves the above problems is Mn: 0.5 mass% or more and 2.0 mass% or less, Zn: 1.0 mass% or more and 4.0 mass% or less (hereinafter, mass% is simply referred to as%. An aluminum alloy core comprising the balance Al and inevitable impurities, a fin made of a brazing sheet comprising an aluminum alloy brazing material clad on at least one surface of the core, and a Zn anticorrosive layer In the aluminum alloy heat exchanger integrated with the aluminum alloy tube having brazing by brazing, the fin includes a residual brazing material layer, and the residual brazing material layer has an equivalent circle diameter of 0. 2.5μm following Si based precipitate more .1μm exists 10000 / mm ² or more 500 000 / mm ² or less, Fi to the fin It is made of an aluminum alloy heat exchanger, wherein the Tsu City of potential nobler to within 50 mV.

Further, the second heat exchanger of the present invention contains Mn: 0.5% or more and 2.0% or less, Zn: 1.0% or more and 4.0% or less, and remaining aluminum and inevitable impurities. An alloy core material, a fin made of a brazing sheet comprising an aluminum alloy brazing material clad on at least one surface of the core material, and an aluminum alloy tube having a Zn anticorrosive layer are integrated by brazing. In the heat exchanger made of aluminum alloy, the fin includes a residual brazing material layer, and 10,000 Si-based precipitates having an equivalent circle diameter of 0.1 μm or more and 2.5 μm or less are included in the residual brazing material layer. / mm ² or more 350,000 pieces / mm ² present below, aluminum alloy heat potential of the fillet relative to the fins, characterized in that a noble to within -50mV It is an exchanger.

  In these heat exchangers, the core material of the brazing sheet is further Si: 0.1% to 1.0%, Fe: 0.05% to 1.0%, Cu: 0.05% 1.0% or less, Mg: 0.05% or more and 1.0% or less, Ti: 0.05% or more and 0.3% or less, Zr: 0.05% or more and 0.3% or less, Cr: 0.3% or less. One or more elements of 05% to 0.3% and V: 0.05% to 0.3% may be contained.

  Also, the aluminum alloy tube contains Cu: 0.1% or more and 0.8% or less, Mn: 0.05% or more and 0.5% or less, and is made of an aluminum alloy composed of the balance Al and inevitable impurities. preferable.

Then, Zn anticorrosion layer of the aluminum alloy tube, ones that Zn application amount is 3 g / ^{m 2} or more 15 g / ^{m 2} or less.

  The manufacturing method of the 1st heat exchanger of this invention assembles the fin and tube which consist of a brazing sheet, performs brazing addition heat which hold | maintains for 1 minute or more and 15 minutes or less at the temperature of 590 degreeC or more and 630 degrees C or less, Then, 500 After cooling to room temperature with a cooling rate in the range of from ° C to 200 ° C being 50 ° C / min or higher, the temperature is maintained at 250 ° C or higher and lower than 400 ° C for 3 minutes or longer and 30 hours or shorter.

  The manufacturing method of the 2nd heat exchanger of this invention assembles the fin which consists of a brazing sheet, and an extrusion flat tube, performs brazing addition heat which hold | maintains for 1 minute or more and 15 minutes or less at the temperature of 590 degreeC or more and 630 degrees C or less, After cooling to room temperature with a cooling rate in the range of 500 ° C. to 200 ° C. being 50 ° C./min or higher, the temperature is maintained at 400 ° C. or higher and 450 ° C. or lower for 5 to 15 hours.

  In addition, about the heat exchanger manufactured by hold | maintaining 5 h or more and 15 h or less at the temperature of 400 to 450 degreeC above, you may hold | maintain for 3 minutes or more and 30 h or less at the temperature of 250 degreeC or more and less than 400 degreeC.

  The aluminum alloy heat exchanger according to the present invention suppresses the preferential corrosion of the fillet by bringing the potential of the fin close to the potential of the fillet and maintains the connection between the fin and the tube, so Increases the corrosion resistance in the atmospheric environment by increasing the time during which the material acts as a sacrificial anode material. The heat exchanger according to the present invention has excellent corrosion resistance in the atmospheric environment, and can be manufactured by heating again after brazing, so that it is excellent in manufacturability and requires heat resistance in the atmospheric environment. Can also be used effectively.

  Hereinafter, the 1st, 2nd aluminum alloy heat exchanger which concerns on this invention is demonstrated in detail based on the embodiment. As described above, each of the first and second aluminum alloy heat exchangers according to the present invention includes a fin made of a brazing sheet in which an aluminum alloy brazing material is clad on an aluminum alloy core material, an aluminum alloy tube, It is constructed by brazing and joining. The brazing material of the brazing sheet forms a fillet, and part of the brazing material remains on the fin surface to form a residual brazing material layer. In the following description, after describing the structure of the brazing sheet constituting the fin and the structure of the tube, characteristics of the material structure of the residual brazing filler metal layer and the relationship between the potential of the fillet and the potential of the fin will be described. . In the specification of the present application, when “%” is simply described with respect to the description of the component composition of the alloy, it means “mass%”.

(1) Structure of Fin (Brazing Sheet) (1.1) Core Material Component of Brazing Sheet As described above, the core material of the brazing sheet constituting the fin contains Mn and Zn, and is composed of the balance Al and inevitable impurities. In addition, as other selectively added elements, one or more of Si, Fe, Cu, Mg, Ti, Zr, Cr, and V can be included. Hereinafter, the content and action of each component will be described.

Mn: 0.5% or more and 2.0% or less Mn crystallizes or precipitates as an Al—Mn-based intermetallic compound, and contributes to improvement of 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. Therefore, the Mn content is 0.5% or more and 2.0% or less.

Zn: 1.0% or more and 4.0% or less Zn lowers the pitting potential of Al. When Zn diffuses from the core material to the brazing material at the time of brazing, Zn diffuses throughout the fin and exerts a sacrificial anticorrosive action on the tube. If the Zn content is less than 1.0%, this effect is insufficient. If the Zn content exceeds 4.0%, the Zn concentration of the fillet increases, and the potential difference between the fin and the fillet is increased even after heat treatment after brazing. It becomes large and cannot suppress the preferential corrosion of the fillet. Furthermore, the self-corrosion rate of the fin is increased, and the sacrificial anticorrosive action disappears early as the fin is consumed. Therefore, the Zn content is 1.0% to 4.0%.

Si: 0.1% or more and 1.0% or less Si is a selective additive element. 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. If the Si content is less than 0.1%, the effect is small. 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. Therefore, the Si content is preferably 0.1% or more and 1.0% or less.

Fe: 0.05% or more and 1.0% or less Fe is also a selective additive element. Fe crystallizes or precipitates as an intermetallic compound and improves the core material strength. In addition, an Al—Mn—Fe, Al—Fe—Si, and Al—Mn—Si—Fe compound phase is formed to lower the solid solubility of Mn and Si in the matrix and raise the melting point of the matrix. If the Fe content is less than 0.05%, the effect is small. If it exceeds 1.0%, the corrosion rate increases, and the appearance of giant crystallized products deteriorates casting and rollability. Therefore, the Fe content is preferably 0.05% or more and 1.0% or less.

Cu: 0.05% or more and 1.0% or less Cu is also a selective additive element. Cu is dissolved in the matrix to improve the strength, enhance the potential of the core material, and increase the potential difference from the residual brazing material to improve the sacrificial anticorrosive effect of the residual brazing material. When the Cu content is less than 0.05%, the effect is small. If it exceeds 1.0%, the melting point of the matrix is lowered, so that the material is easily melted during brazing. Therefore, the Cu content is preferably 0.05% or more and 1.0% or less.

Mg: 0.05% to 1.0% Mg is also a selective additive element. Mg improves the strength by being finely precipitated as Mg ₂ Si. If the Mg content is less than 0.05%, the effect is small. If it exceeds 1.0%, brazing properties may be impaired, or intergranular corrosion may occur, resulting in a decrease in corrosion resistance. Therefore, the Mg content is preferably 0.05% or more and 1.0% or less.

Ti: 0.05% or more and 0.3% or less Ti is also a selective additive element. Ti forms a fine intermetallic compound and improves the strength of the alloy and the self-corrosion resistance of the core material. If the Ti content is less than 0.05%, the effect cannot be sufficiently obtained. If it exceeds 0.3%, a coarse compound is generated in the ingot, and cracks occur during hot rolling. Therefore, the Ti content is preferably 0.05% or more and 0.3% or less.

Zr, Cr, V: 0.05% or more and 0.3% or less Zr, Cr, V are also selectively added elements. All of these elements form fine intermetallic compounds and improve the strength. If the content of Zr, Cr, V is less than 0.05%, the effect cannot be obtained sufficiently. If it exceeds 0.3%, the formability is lowered, and cracking occurs during processing. Therefore, the content of Zr, Cr, V is preferably 0.05% or more and 0.3% or less.

(1.2) Components of brazing material of brazing sheet An aluminum alloy brazing sheet used for fins is provided with a brazing material on at least one surface for the purpose of brazing with a tube. The brazing material is not particularly limited, and examples thereof include aluminum alloys defined in JIS 4343, JIS 4045, and the like. The brazing material of the brazing sheet forms a fillet between the fin material and the tube material at the time of brazing and joining. A part of the brazing material remains on the surface of the core material after brazing and becomes a residual brazing material layer.

(2) Structure of tube (2.1) Component of tube Next, the composition component of the aluminum alloy which comprises the tube of the aluminum alloy heat exchanger which concerns on this invention, and its effect | action are demonstrated. The tube is made of an aluminum alloy containing Cu, Mn, and the balance Al and inevitable impurities. The tube material of the aluminum alloy heat exchanger according to the present invention is preferably applied in the form of an extruded flat tube.

Cu: 0.1% or more and 0.8% or less Cu is dissolved in the matrix to improve the strength, sacrificial anticorrosion by the sacrificial anode material by making the potential noble and increasing the potential difference from the sacrificial anode material. Improve the effect. When the Cu content is less than 0.1%, the effect is small. If it exceeds 0.8%, the melting point of the matrix is lowered, so that the material is easily melted during brazing. Therefore, the Cu content is preferably 0.1% or more and 0.8% or less.

Mn: 0.05% or more and 0.5% or less Mn crystallizes or precipitates as an Al—Mn-based intermetallic compound to improve the strength after heat of brazing addition and to make the potential noble by solute Mn. . In order to obtain this effect, the Mn content needs to be 0.05% or more. However, if the Mn content exceeds 0.5%, the extrudability is lowered, and a huge intermetallic compound is crystallized, which may impair the productivity. Therefore, the content of Mn is preferably 0.05% or more and 0.5% or less.

(2.2) Zn anticorrosion layer The tube of the aluminum alloy heat exchanger according to the present invention has a Zn anticorrosion layer on its outer surface. The Zn anticorrosion layer is formed when Zn is applied to the outer surface of a tube formed by extrusion or the like by thermal spraying and the tube is brazed. At least a part of Zn applied to the outer surface of the tube diffuses into the tube during the brazing process. In the present invention, the Zn anticorrosion layer includes a Zn diffusion layer formed on the tube surface by this brazing treatment and an undiffused Zn layer on the outer surface of the tube. Since the Zn diffusion layer has a lower pitting corrosion potential than the portion of the aluminum alloy of the tube where Zn is not diffused, the Zn anticorrosion layer including this Zn diffusion layer protects the aluminum alloy by the sacrificial anticorrosion effect, It is possible to improve the durable life.

In the present invention, the amount of Zn applied to the tube as the Zn anticorrosion layer is 3 g / m ² or more and 15 g / m ² or less. When the Zn application amount is less than 3 g / m ² , the sacrificial anticorrosive effect is not sufficiently exhibited, and corrosion that leads to early penetration may occur in the tube. On the other hand, if the Zn application amount exceeds 15 g / m ² , the corrosion protection layer is consumed at an early stage due to an increase in the corrosion rate, or the Zn concentration in the fillet becomes higher than the fin and may cause preferential corrosion of the fillet. There is. Therefore, the Zn content is preferably 3 g / m ² or more and 15 g / m ² or less.

(3) Residual brazing filler metal layer and potential configuration of fin and fillet As already described, the first and second aluminum alloy heat exchangers according to the present invention both have residual brazing filler metal on the surface of the fin. Has a layer. The present invention is characterized in that the material structure of the residual brazing material layer is controlled. Specifically, the number of Si-based precipitates present in the residual brazing filler metal layer and having an equivalent circle diameter of 0.1 μm to 2.5 μm is defined. This is because the effect of improving the corrosion resistance of the residual brazing filler metal layer can be obtained by appropriately dispersing the Si-based precipitate. This effect is because the corrosion reaction is dispersed by finely dispersing Si-based precipitates that become cathode sites. In addition, the precipitation of Si decreases the Si solid solubility in the residual brazing material, thereby lowering the pitting corrosion potential, lowering the residual brazing potential lower than the fillet potential, and suppressing the preferential corrosion of the fillet. There is also an effect that is done. By improving the corrosion resistance of the residual brazing filler metal as described above and suppressing the preferential corrosion of the fillet, the peeling of the fin is prevented, and the corrosion resistance of the heat exchanger is improved by increasing the time during which the sacrificial corrosion protection of the fin acts.

  In the first and second aluminum alloy heat exchangers according to the present invention, the fin potential and the fillet potential are close to each other. The top priority in corrosion protection of heat exchangers is the corrosion protection of the tube, which is achieved by using fins as sacrificial anode materials. Therefore, it is no exaggeration to say that the quality of the corrosion resistance of the heat exchanger is determined by how long the function of the fins as the sacrificial anode material is maintained. In the present invention, the difference between the potential configurations of the fin and the fillet is suppressed within a certain range. Thereby, excessive corrosion of the fin and preferential corrosion of the fillet are suppressed, and the function of the fin as a sacrificial anode material is appropriately exhibited. And since a fin has moderate corrosion resistance by material structure control of said residual brazing filler metal layer, the function as a sacrificial anode material can be maintained for a long time with the original function of a fin.

  Here, regarding the first and second aluminum alloy heat exchangers according to the present invention, the material structure of the residual brazing filler metal layer and the potential configuration of the fins and fillets will be described.

(3.1) Material structure and potential configuration of first heat exchanger The material structure of the residual brazing filler metal layer in the first aluminum alloy heat exchanger of the present application is 0. The number of Si-based precipitates of 1 μm or more and 2.5 μm or less is 10000 / mm ² or more and 500000 / mm ² or less. When the number of Si-based precipitates is less than 10,000 / mm ² , Si is not sufficiently precipitated, and the corrosion resistance improving effect and potential reduction cannot be sufficiently obtained. On the other hand, there is a limit to the number of Si-based precipitates deposited on the residual brazing filler metal, and it is difficult to deposit over 500,000 pieces / mm ² .

  And in the 1st aluminum alloy heat exchanger of this application, the electric potential of a fillet is noble in the range within 50 mV with respect to a fin. When the potential of the fillet with respect to the fin exceeds 50 mV, the sacrificial anticorrosive effect of the fin around the fillet on the fillet increases, and the fin peels off due to the corrosion of the fin. The sacrificial anticorrosive effect does not act on the tube due to the loss of the fin due to the fin peeling. Therefore, the fillet potential with respect to the fin is noble within a range of 50 mV. In this first aluminum alloy heat exchanger, the fillet potential is “noble” with respect to the fins. Therefore, it is preferable that the potential difference of the fillet with respect to the fin is on the positive side from 0 mV.

(3.2) Material structure and potential configuration of second heat exchanger The material structure of the residual brazing filler metal layer in the second aluminum alloy heat exchanger of the present application is 0. The number of Si-based precipitates of 1 μm or more and 2.5 μm or less is 10000 / mm ² or more and 350,000 / mm ² or less. The reason why the number of Si-based precipitates is 10,000 pieces / mm ² or more is the same reason as in the first heat exchanger. In addition, the second heat exchanger is heat-treated at a temperature of 400 ° C. or higher and 450 ° C. or lower after the brazing is completed for manufacturing. In the heat treatment in this temperature range, it is difficult to deposit more than 350,000 Si-based precipitates / mm ² .

  And in the 2nd aluminum alloy heat exchanger of this application, with respect to a fin, the electric potential of a fillet is base in the range within -50mV. When the fillet potential exceeds −50 mV with respect to the fin and becomes base, preferential corrosion of the fillet occurs. Fillet corrosion is a factor in fin peeling. Due to the loss of fins due to the peeling of the fins, the sacrificial anticorrosive effect does not act on the tube, and the corrosion of the tube proceeds. Therefore, the base of the fillet potential is within -50 mV with respect to the fin. In the second aluminum alloy heat exchanger, the fillet potential is “base” relative to the fin. Therefore, it is preferable that the potential difference of the fillet with respect to the fin is on the negative side from 0 mV. However, in the case of the second aluminum alloy heat exchanger, the temperature of the heat treatment is high, and the Zn in the fillet may diffuse into the fin and the Zn concentration in the fin and fillet may be approximately the same. In this case, the fin and the fillet corrode simultaneously, but if the residual brazing filler metal layer corrodes and the core material is exposed, the fin core material having a high Zn concentration acts as a sacrificial anode, so the potential difference may be 0 mV.

(4) Manufacturing method of aluminum alloy heat exchanger Next, the manufacturing method of the aluminum alloy heat exchanger which concerns on this application is demonstrated. The manufacturing method of the 1st and 2nd heat exchanger of this application is fundamentally common. That is, it is common in the process of assembling the brazing sheet fins and tubes, subjecting them to brazing addition heat, and once cooling to room temperature. In these steps, the conditions for brazing heating and the cooling conditions are also common. On the other hand, in the manufacturing method of the 1st and 2nd heat exchanger of this application, after heat brazing completion, predetermined heat processing is performed and there is a difference in each condition. Therefore, in the following description, first, a stage for preparing a brazing sheet and a tube to be a common fin and a brazing process thereof will be described. And the heat processing after the completion of brazing for manufacturing the first and second heat exchangers will be described respectively.

  As for the method for producing the aluminum alloy brazing sheet used for the fin of the present invention, a usual method can be adopted, and it is not particularly limited, but for example, the following is preferable.

  Both sides of the ingot of the core material and the brazing material are chamfered, and the clad layer is overlaid. This is preheated at 400 ° C. to 500 ° C. for 1 h to 10 h, and the thickness is reduced to about 5 mm by hot rolling. Further, cold rolling is performed to obtain a brazing sheet having a thickness of about 0.08 mm. In order to adjust the mechanical properties, a final annealing of 300 to 450 ° C. and 1 to 10 hours may be added. The obtained brazing sheet is cut into appropriate dimensions, and then appropriately processed by corrugation or the like in order to obtain a shape suitable as a fin of the heat exchanger.

  In addition, the aluminum alloy tube of the present invention is preferably manufactured by producing an ingot of an aluminum alloy and processing it into the form of an extruded flat tube. As a method for producing the extruded flat tube made of aluminum alloy, a normal method can be adopted, and it is not particularly limited, but for example, the following is preferable.

  The ingot is homogenized and faced as necessary, and the billet is heated to 450 ° C. or higher and 570 ° C. or lower before extrusion. After the billet is extruded, drawing is performed so as to obtain a predetermined thickness. Then, Zn is applied to the outer surface of the molded tube. Examples of the Zn application method include Zn spraying, Zn coating, and Zn plating. In the above-described tube manufacturing process, heat treatment may be performed in a timely manner at any stage of the manufacturing process in order to adjust mechanical characteristics.

  The aluminum alloy heat exchanger is manufactured by assembling the aluminum alloy brazing sheet prepared as described above and an aluminum alloy extruded flat tube and brazing them together. When assembling the fin and the tube, it is preferable to assemble together other heat exchanger parts such as a tank.

  In the brazing joint between the fin and the tube, brazing addition heat is maintained at 590 ° C. or more and 630 ° C. or less for 1 min or more and 15 min or less, and then cooled. When the holding temperature is less than 590 ° C., brazing becomes insufficient because the temperature is low. If the holding temperature exceeds 630 ° C., significant wax erosion may occur. If the holding time is less than 1 min, brazing becomes insufficient because the holding time is short. If the holding time exceeds 15 min, significant wax erosion may occur.

  After brazing, cooling is performed from the brazing addition heat temperature to room temperature, but it is necessary to cool at a cooling rate of 50 ° C./min or more in a temperature range between 500 ° C. and 200 ° C. By rapidly cooling at 50 ° C./min or more, Si in the residual brazing material is dissolved in a supersaturated state, and Si particles are precipitated in a finer and denser state in the residual brazing material by the heat treatment after the brazing is completed. This is because that. As described above, this Si particle can be expected to increase the corrosion resistance life. If the cooling rate is less than 50 ° C./min, Si of the residual brazing filler metal precipitates during cooling, and the solid solution amount of Si in the residual brazing filler metal decreases, and Si-based precipitates in the heat treatment after cooling decrease. The effect of improving the corrosion resistance cannot be obtained. The cooling rate in the temperature range from 500 ° C. to 200 ° C. after the brazing heating is 50 ° C./min or more, and more preferably 100 ° C./min or more. The reason why the cooling rate in the temperature range between 500 ° C. and 200 ° C. is defined is that precipitation of Si occurs in this temperature range. The brazed heat exchanger is cooled to room temperature to complete the brazing, and then subjected to a heat treatment to become the first or second heat exchanger.

(4.1) Post-brazing heat treatment for manufacturing the first heat exchanger To manufacture the first heat exchanger, after the brazing is completed, the heat treatment is further performed at 250 ° C. or higher and lower than 400 ° C. for 3 minutes or longer and 30 hours or shorter. Heat treatment is performed. By this heat treatment, Si-based precipitates are densely precipitated in the brazing material. If the temperature of the heat treatment is lower than 250 ° C., it is difficult to obtain an appropriate dispersion state of Si-based precipitates within an industrially possible time. In the precipitation treatment at a temperature higher than 400 ° C., coarse Si-based precipitates are easily formed, and the dispersion of corrosion becomes rough and the anticorrosion effect becomes low. Further, if the heat treatment time is shorter than 3 min, the precipitation cannot be promoted sufficiently. If the heat treatment time is long, an effect of improving the corrosion resistance can be obtained. However, if the heat treatment time is longer than 30 hours, the cost is increased. The heat treatment performed after brazing may be performed in the air, in an inert gas atmosphere, or in a vacuum.

(4.2) Heat treatment after brazing for the production of the second heat exchanger In order to produce the second heat exchanger, a heat treatment for diffusing Zn concentrated in the fillet into the member in contact with the fillet is performed. . This heat treatment is a heat treatment of not less than 400 ° C. and not more than 450 ° C. and not less than 5 hours and not more than 15 hours after completion of brazing. In this heat treatment, Si-based precipitates are deposited more densely in the residual brazing material as Zn diffuses. If the heat treatment temperature is lower than 400 ° C., it will be difficult to diffuse the fillet Zn within an industrially possible time. Also, in this heat treatment, precipitation of Si-based precipitates occurs simultaneously with the diffusion of Zn, but in the case of precipitation treatment at a temperature higher than 450 ° C., coarse Si-based precipitates are easily formed, and the dispersion of corrosion becomes rough. The anticorrosive effect is lowered. Further, if the heat treatment time is shorter than 5 hours, Zn diffusion cannot be promoted sufficiently. Since heat treatment for 15 hours or longer does not change the Zn diffusion state, it may be up to about 15 hours. The heat treatment performed after brazing may be performed in the air, in an inert gas atmosphere, or in a vacuum.

  Note that after heat treatment at 400 ° C. or higher and 450 ° C. or lower for 5 hours or longer and 15 hours or shorter, it may be further held at a temperature of 250 ° C. or higher and lower than 400 ° C. for 3 minutes or longer and 30 hours or shorter.

  EXAMPLES Hereinafter, although this invention is demonstrated in detail based on an Example, this invention is not limited to this.

[Manufacture of brazing sheets (fins)]
By semi-continuous casting, a core material alloy and a brazing material alloy were cast with the compositions shown in Table 1, and each was rolled to produce a core material and a brazing material plate. At this time, the plate thickness was adjusted so that the clad rate on one side was 12% when clad. Next, the manufactured core material plate and brazing material plate are clad, combined heating, hot rolling cold rolling is performed, intermediate annealing is performed, and then cold rolling is performed to obtain a brazing sheet having a thickness of 0.08 mm. Produced. The produced brazing sheet was slit into a width of 14 mm and corrugated to obtain fins.

[Manufacture of tubes]
Billets were prepared by melting and casting an aluminum alloy with the composition shown in Table 2. The billet was subjected to homogenization heat treatment and chamfering, and then extruded to spray the amount of Zn shown in Table 2. By this processing, an extruded flat tube made of aluminum alloy having a height of 2 mm, a width of 14 mm, and a wall thickness of 0.35 mm was produced.

[Manufacture of heat exchangers]
And the produced fin and tube were assembled | attached, and the brazing was performed in nitrogen atmosphere after apply | coating and drying KF-AlF type | system | group flux powder. And after brazing completion, it heat-processed in air | atmosphere atmosphere. Here, a heat exchanger was manufactured by variously setting the heating temperature at the time of brazing, the cooling rate in the range of 500 ° C. to 200 ° C. after brazing, and the heat treatment conditions after completion of brazing. Moreover, the 1st, 2nd heat exchanger is manufactured by the condition setting of the heat processing conditions after brazing completion. Tables 3 and 4 show the manufacturing conditions of the heat exchangers of the examples and comparative examples. No. in Table 3 C1 to C69 (Examples 1 to 51, Comparative Examples 1 to 18) correspond to the first heat exchanger. In Table 4, No. C70 to C139 (Examples 52 to 103, Comparative Examples 19 to 36) correspond to the second heat exchanger.

[Examination of heat exchanger configuration and corrosion resistance evaluation]
About the heat exchanger produced with said manufacturing method, (i) Si type deposit distribution in a residual brazing filler metal layer, (ii) Potential measurement of a fin and a fillet, (iii) Corrosion resistance evaluation was performed. Each examination / evaluation method was as follows.

(I) Si-based precipitate distribution in the residual brazing filler metal layer A sample was cut out from the produced heat exchanger, resin-filled and mirror-polished, and the residual brazing filler was photographed at three magnifications with an optical microscope at a magnification of 1000 times. . From the photographed image, the number of Si-based precipitates with a circle equivalent of 0.1 μm or more and 2.5 μm or less was measured using image processing software (Image-J), and divided by the measurement area, thereby Si-based precipitates. Distribution (pieces / mm ² ) was obtained.

(Ii) Measurement of fin and fillet potential A sample was cut out from the produced heat exchanger so as to include the fin and fillet. Samples containing fillets were filled with resin and masked except for the fillets after mirror polishing. A solution in which 15 mL / L acetic acid was added to 5% NaCl was kept at 25 ° C., an Ag / AgCl electrode was used as a reference electrode, a sample masked except for fins and fillets was immersed, and a potential value after 30 min was recorded. . The potential difference between the fin and the fillet was calculated from the measured value.

(Iii) Evaluation of corrosion resistance A sample was cut out from the produced heat exchanger so that the tube length was 10 cm. After the SWAAT test was conducted for 1000 hours, the sample was filled with resin, mirror-polished, and three-field observation of the corrosion state of the fillet was performed with an optical microscope. The evaluation is “◎” when the fillet remains in all three fields of view, and “◯” when the fillet disappears in one of the three fields but the connection between the fin and the tube is recognized. Among them, the case where the fillet disappeared in two or more fields of view but the connection between the fin and the tube was recognized was “Δ”, and the case where the fillet disappeared and the fin was peeled off was designated “x”. Furthermore, even if the corrosion condition of the fillet was “◎”, “◯”, or “Δ”, the corrosion resistance was evaluated as “x” for the sample in which the tube portion was corroded.

(Iv) Comprehensive evaluation In addition to the above-described corrosion resistance evaluation, evaluation was performed in consideration of workability and brazing properties of fins and tubes. That is, a comprehensive evaluation was performed in consideration of the state in which the heat exchanger could not be manufactured such that fins or tubes could not be processed or brazing failure occurred. In addition, even if the heat exchanger could be manufactured, it was considered that it could be easily deformed. Then, those having good corrosion resistance and capable of functioning as a heat exchanger were evaluated as “又 は” or “（” (“か” or “○” was distinguished according to the corrosion resistance evaluation result). And what was not able to manufacture a heat exchanger because it was not processable, or what was not able to endure use as a heat exchanger on strength was evaluated as "x", even if corrosion resistance was favorable.

  Tables 5 and 6 show the measured Si-based precipitate distribution in the residual brazing filler metal layer, the potential difference between the fins and the fillets, and the corrosion resistance evaluation results and the overall evaluation of the heat exchangers of the examples and comparative examples. At the same time, based on each table, considerations for each example and comparative example are described below.

(A) Examples 1 to 51 and Comparative Examples 1 to 18 (first heat exchanger)
(A-1) Influence of composition of core material of fin Examples 1 to 5 are examples in which only Mn and Zn were added in appropriate amounts to the core material of the fin, and satisfied the relationship between the potential of the fillet relative to the fin and the corrosion resistance.
Examples 6 to 9 are examples in which Si was added to the core material of Example 1. The relationship between the fillet potential and the fin was satisfied, and the corrosion resistance was not a problem.
Examples 10 to 13 are examples in which Fe was added to the core material of Example 1. The relationship between the fillet potential and the fin was satisfied, and the corrosion resistance was not a problem.
Examples 14 to 17 are examples in which Cu was added to the core material of Example 1. The relationship between the fillet potential and the fin was satisfied, and the corrosion resistance was not a problem.
Examples 18 to 21 are examples in which Mg was added to the core material of Example 1. The relationship between the fillet potential and the fin was satisfied, and the corrosion resistance was not a problem.
Examples 22 to 25 are examples in which Ti was added to the core material of Example 1. The relationship between the fillet potential and the fin was satisfied, and the corrosion resistance was not a problem.
Examples 26 to 29 are examples in which Zr was added to the core material of Example 1. The relationship between the fillet potential and the fin was satisfied, and the corrosion resistance was not a problem.
Examples 30 to 33 are examples in which Cr was added to the core material of Example 1. The relationship between the fillet potential and the fin was satisfied, and the corrosion resistance was not a problem.
Examples 34 to 37 are examples in which V was added to the core material of Example 1. The relationship between the fillet potential and the fin was satisfied, and the corrosion resistance was not a problem.

In contrast to Examples 1 to 37 described above, in Comparative Examples 1 to 4, the amount of Mn and the amount of Zn added to the core material of the fin are outside the preferred ranges.
In Comparative Example 1, the amount of Mn added to the core material of the fin was small, the relationship between the potential of the fillet with respect to the fin was satisfied, and the corrosion resistance was not a problem. The deformation is recognized and cannot be used as a heat exchanger.
In Comparative Example 2, since the amount of Mn added to the core material of the fin was too large, the fin could not be shaped and could not be evaluated.
In Comparative Example 3, since the amount of Zn added to the core material of the fin was small, the sacrificial anticorrosive effect on the tube was weak, and corrosion was observed on the tube surface.
In Comparative Example 4, because the amount of Zn added to the core material of the fin was large, the Zn was concentrated in the fillet, the fin peeling due to the preferential corrosion of the fillet occurred, the sacrificial anticorrosive effect was not exhibited, and corrosion was observed on the tube surface It was.

(A-2) Influence of tube composition Examples 38 to 41 are examples in which the fins of Example 1 were used and only appropriate amounts of Cu and Mn were added to the tube, and the relationship of the fillet potential to the fins. And satisfied the corrosion resistance.

In contrast to Examples 38 to 41, in Comparative Examples 5 to 8, the amounts of Cu and Mn added to the tube are outside the preferred ranges.
In Comparative Example 5, since the amount of Cu added to the tube was small, the potential difference from the fin was small, and corrosion was observed in the tube.
In Comparative Example 6, since the amount of Cu added to the tube was large, Cu was concentrated in the fillet, the potential became noble, corrosion of the brazing material layer around the fillet progressed, and fin peeling occurred.
In Comparative Example 7, since the amount of Mn added to the tube was small, the strength of the tube after brazing was low and easily deformed, so that it could not be used as a heat exchanger.
In Comparative Example 8, since the amount of Mn added to the tube was large, the extrudability was poor and the tube could not be produced.

(A-3) Influence of Zn spraying amount on tube Examples 42 and 43 are the cases where the fins of Example 1 were used, and the Zn spraying amount of the tube was the lower limit and the upper limit, and the relationship between the potential of the fillet with respect to the fin. As a result, the corrosion resistance was not a problem.

In contrast to Examples 42 and 43, in Comparative Examples 9 and 10, the amount of Zn sprayed on the tube is outside the preferred range.
In Comparative Examples 9 and 10, the tube was corroded because the amount of Zn sprayed on the tube was less than the lower limit and exceeded the upper limit.

(A-4) Influence of brazing temperature and time Examples 44 and 45 are examples in which the fins and tubes of Example 1 are used and the brazing temperature is the lower limit and the upper limit. Satisfied the relationship of potential and corrosion resistance.
Examples 46 and 47 are examples in which the fins and tubes of Example 1 were used and the brazing time was the lower limit and the upper limit, and the relationship between the potential of the fillet relative to the fins and the corrosion resistance were satisfied.

  In contrast to the above Examples, since Comparative Examples 11 to 14 had a brazing temperature and a brazing time that were less than the lower limit and exceeded the upper limit, a brazing defect occurred and could not be evaluated.

(A-5) Influence of cooling rate after brazing Example 48 is an example in which the fin and tube of Example 1 are used, and the cooling rate after brazing is the lower limit. The result was that the potential relationship was satisfied and the corrosion resistance was not a problem.

  On the other hand, in Comparative Example 15, since the cooling rate after brazing was slow, the number of generated Si-based precipitates was small, and the potential of the fins was not reduced.

(A-6) Effect of heat treatment conditions after completion of brazing Example 49 is an example in which the fin and tube of Example 1 are used, and the heat treatment temperature after completion of brazing is the lower limit. The relationship between the fillet potentials was satisfied and the corrosion resistance was not a problem.
Examples 50 and 51 are examples in which the fins and tubes of Example 1 are used, and the heat treatment time after completion of brazing is the lower limit and the upper limit, satisfying the relationship between the potential of the fillet with respect to the fins, and corrosion resistance The result was not a problem.

In contrast to Examples 47 to 50 in which the heat treatment conditions after the completion of brazing were appropriate, Comparative Examples 16 to 19 were those in which the heat treatment temperature or heat treatment time was out of the preferred range.
In Comparative Example 16, since the heat treatment temperature after the completion of brazing was low, Si-based precipitates did not precipitate, and fin peeling due to fillet preferential corrosion occurred.
In Comparative Example 17, the heat treatment time after brazing addition heat was short, so the number of Si-based precipitates was small, and the fin potential was not lower than the fillet potential. Therefore, preferential corrosion of the fillet has occurred.
Comparative Example 18 satisfied the relationship between the potential of the fillet relative to the fin and the corrosion resistance. However, the heat treatment time after the completion of brazing is as long as 50 hours, and the production cost is high and cannot be industrially produced.

(B) Examples 52 to 103 and Comparative Examples 19 to 36 (second heat exchanger)
(B-1) Influence of composition of fin core material Examples 52 to 56 were examples in which Mn and Zn were added in appropriate amounts to the core material of the fin, and satisfied the relationship between the potential of the fillet relative to the fin and the corrosion resistance.
Examples 57 to 60 are examples in which Si was added to the core material of Example 52. The relationship between the fillet potential and the fin was satisfied, and the corrosion resistance was not a problem.
Examples 61 to 64 are examples in which Fe was added to the core material of Example 52. The relationship between the fillet potential and the fin was satisfied, and the corrosion resistance was not a problem.
Examples 65 to 68 are examples in which Cu was added to the core material of Example 52. The relationship between the fillet potential and the fin was satisfied, and the corrosion resistance was not a problem.
Examples 69 to 72 are examples in which Mg was added to the core material of Example 52. The relationship between the fillet potential and the fin was satisfied, and the corrosion resistance was not a problem.
Examples 73 to 76 are examples in which Ti was added to the core material of Example 52. The relationship between the fillet potential and the fin was satisfied, and the corrosion resistance was not a problem.
Examples 77 to 80 are examples in which Zr was added to the core material of Example 52. The relationship between the fillet potential and the fin was satisfied, and the corrosion resistance was not a problem.
Examples 81 to 84 are examples in which Cr was added to the core material of Example 52. The relationship between the fillet potential and the fin was satisfied, and the corrosion resistance was not a problem.
Examples 85 to 88 are examples in which V was added to the core material of Example 52. The relationship between the fillet potential and the fin was satisfied, and the corrosion resistance was not a problem.

In contrast to the above Examples 52 to 88, in Comparative Examples 19 to 22, the amounts of Mn and Zn added to the core material of the fin are out of the preferred ranges.
In Comparative Example 19, the amount of Mn added to the core material of the fin was small, and the relationship of the potential of the fillet with respect to the fin was satisfied, and the corrosion resistance was not a problem. The deformation is recognized and cannot be used as a heat exchanger.
In Comparative Example 20, since the amount of Mn added to the core material of the fin was too large, the fin could not be shaped and could not be evaluated.
In Comparative Example 21, since the amount of Zn added to the fin core was small, the Zn concentration in the fillet was low, and the brazing filler metal layer around the fillet had a lower potential, so the periphery of the fillet was corroded and fin peeling occurred. did.
In Comparative Example 22, since the amount of Zn added to the fin core material was large, the Zn concentration in the fillet was significant, so that it could not be diffused by the heat treatment, and fin peeling due to the preferential corrosion of the fillet occurred.

(B-2) Influence of tube composition Examples 89 to 92 are examples in which the fins of Example 52 were used, and only appropriate amounts of Cu and Mn were added to the tube, and the relationship of the fillet potential to the fins. And satisfied the corrosion resistance.

In contrast to Examples 89 to 92, in Comparative Examples 23 to 26, the amounts of Cu and Mn added to the tube are out of the preferred ranges.
In Comparative Example 23, since the amount of Cu added to the tube was small, Cu was not contained in the fillet, and since the potential of the fillet was base, preferential corrosion occurred and fin peeling occurred.
In Comparative Example 24, since the amount of Cu added to the tube was large, Cu was concentrated in the fillet, the potential became noble, corrosion of the brazing material layer around the fillet progressed, and fin peeling occurred.
In Comparative Example 25, since the amount of Mn added to the tube was small, the strength of the tube after brazing was low, and the tube was easily deformed, so that it could not be used as a heat exchanger.
In Comparative Example 26, since the amount of Mn added to the tube was large, the extrudability was poor and a tube could not be produced.

(A-3) Influence of Zn spray amount on tube Examples 93 and 94 are the cases where the fin of Example 52 is used, and the Zn spray amount of the tube is the lower limit and the upper limit, and the relationship between the potential of the fillet with respect to the fin. As a result, the corrosion resistance was not a problem.

Compared with Examples 93 and 94, Comparative Examples 27 and 28 have a Zn spraying amount of the tube outside the preferred range.
In Comparative Examples 27 and 28, corrosion was observed in the tubes because the amount of Zn sprayed on the tubes was less than the lower limit and exceeded the upper limit.

(B-4) Influence of brazing temperature and time Examples 95 and 96 are examples in which the fin and tube of Example 52 are used, and the brazing temperature is the lower limit and the upper limit. Satisfied the relationship of potential and corrosion resistance.
Examples 97 and 98 are examples in which the fin and tube of Example 52 were used and the brazing time was the lower limit and the upper limit, and the relationship between the potential of the fillet relative to the fin and the corrosion resistance were satisfied.

  In contrast to the above examples, Comparative Examples 29 to 32 had a brazing temperature and a brazing time that were less than the lower limit and exceeded the upper limit.

(B-5) Influence of Cooling Rate after Brazing Example 99 is an example in which the fin and tube of Example 52 are used, and the cooling rate after brazing is the lower limit. The result was that the potential relationship was satisfied and the corrosion resistance was not a problem.

  On the other hand, in Comparative Example 33, since the cooling rate after brazing was slow, the number of produced Si-based precipitates was small, and the potential of the fin was not reduced, so that it did not approach the fillet potential.

(B-6) Effect of heat treatment conditions after completion of brazing Examples 100 and 101 are examples in which the fins and tubes of Example 52 were used, and the heat treatment temperature after completion of brazing was the lower limit and the upper limit. In other words, the relationship between the potential of the fillet to the fin was satisfied, and the corrosion resistance was not a problem.
Examples 102 and 103 are examples in which the fin and tube of Example 52 are used, and the heat treatment time after completion of brazing is the lower limit and the upper limit, satisfying the relationship between the potential of the fillet relative to the fin, and corrosion resistance The result was not a problem.

In contrast to Examples 100 to 103 in which the heat treatment conditions after the completion of brazing are appropriate, Comparative Examples 34, 35, and 36 are those in which the heat treatment temperature or the heat treatment time is out of the preferred range.
In Comparative Example 34, the heat treatment temperature after brazing was high, so the number of Si-based precipitates was small, and the fin potential did not approach the fillet potential. Therefore, preferential corrosion of the fillet has occurred.
In Comparative Example 35, since the heat treatment time after the brazing heat was short, the number of Si-based precipitates was small, and the fin potential did not approach the fillet potential. Therefore, preferential corrosion of the fillet has occurred.
Comparative Example 36 satisfied the relationship between the fillet potential with respect to the fin and the corrosion resistance. However, the heat treatment time after the completion of brazing is as long as 50 hours, and the production cost is high and cannot be industrially produced.

As described above, the aluminum alloy heat exchanger according to the present invention maintains the function of the fin as a sacrificial anode material for a long period of time by suppressing the preferential corrosion of the fillet. The aluminum alloy heat exchanger according to the present invention improves the corrosion resistance in the atmospheric environment. The heat exchanger according to the present invention is excellent in corrosion resistance in an atmospheric environment and is useful for a heat exchanger for an outdoor unit of an air conditioner and an automobile heat exchanger that require corrosion resistance in an atmospheric environment.

Claims (8)

Aluminum alloy containing Mn: 0.5 mass% or more and 2.0 mass% or less, Zn: 1.0 mass% or more and 4.0 mass% or less (hereinafter, mass% is simply described as%), and the balance being Al and inevitable impurities A core made of aluminum, a fin made of a brazing sheet comprising a brazing material made of aluminum alloy clad on at least one surface of the core, and an aluminum alloy tube having a Zn anticorrosive layer were integrated by brazing joint In aluminum alloy heat exchangers,
The fin includes a residual brazing filler metal layer;
The residual brazing material layer, following Si based precipitate 0.1μm or 2.5μm in equivalent circle diameter is present 10000 / mm ² or more 500 000 / mm ² or less,
An aluminum alloy heat exchanger characterized in that the fillet potential is noble within a range of 50 mV or less with respect to the fin. Mn: 0.5% or more and 2.0% or less, Zn: 1.0% or more and 4.0% or less, a core material made of an aluminum alloy composed of the balance Al and inevitable impurities, and at least one surface of the core material In an aluminum alloy heat exchanger in which a fin made of a brazing sheet including a brazing material made of aluminum alloy clad with an aluminum alloy tube having a Zn anticorrosion layer is integrated by brazing,
The fin includes a residual brazing filler metal layer;
In the residual brazing filler metal layer, Si-based precipitates having an equivalent circle diameter of 0.1 μm or more and 2.5 μm or less are present at 10000 / mm ² or more and 350,000 / mm ² or less,
An aluminum alloy heat exchanger characterized in that a fillet potential with respect to the fin is base in a range of -50 mV or less.   The core material of the brazing sheet is further composed of Si: 0.1% to 1.0%, Fe: 0.05% to 1.0%, Cu: 0.05% to 1.0%, Mg: 0 0.05% to 1.0%, Ti: 0.05% to 0.3%, Zr: 0.05% to 0.3%, Cr: 0.05% to 0.3%, V The heat exchanger made of aluminum alloy according to claim 1 or 2, containing one or more elements of 0.05% or more and 0.3% or less.   The aluminum alloy tube contains Cu: 0.1% or more and 0.8% or less, Mn: 0.05% or more and 0.5% or less, and is made of an aluminum alloy composed of the balance Al and inevitable impurities. The heat exchanger made from aluminum alloy in any one of Claim 3. Zn anticorrosion layer of the aluminum alloy tube, aluminum alloy heat exchanger according to any one of claims 1 to 4 that Zn application amount is 15 g / m ² or less 3 g / m ² or more. It is a manufacturing method of the heat exchanger of Claim 1, Comprising:
A brazing sheet fin and a tube are assembled, and brazing addition heat is maintained at a temperature of 590 ° C. or more and 630 ° C. or less for 1 min or more and 15 min or less,
Then, after cooling to room temperature with a cooling rate in the range of 500 ° C. to 200 ° C. being 50 ° C./min or more,
A method for producing an aluminum alloy heat exchanger, characterized by holding at a temperature of 250 ° C. or higher and lower than 400 ° C. for 3 minutes or longer and 30 hours or shorter. It is a manufacturing method of the heat exchanger of Claim 2, Comprising:
A brazing sheet fin and an extruded flat tube are assembled, and brazing addition heat is maintained at a temperature of 590 ° C. or more and 630 ° C. or less for 1 min or more and 15 min or less,
Then, after cooling to room temperature with a cooling rate in the range of 500 ° C. to 200 ° C. being 50 ° C./min or more,
A method for producing a heat exchanger made of aluminum alloy, characterized by holding at a temperature of 400 ° C. or higher and 450 ° C. or lower for 5 hours or longer and 15 hours or shorter. The method for producing an aluminum alloy heat exchanger, wherein the heat exchanger produced by the method according to claim 7 is further held at a temperature of 250 ° C or higher and lower than 400 ° C for 3 minutes or longer and 30 hours or shorter.