ALUMINUM ALLOY HEAT EXCHANGER

Abstract

An aluminum alloy heat exchanger having an atmosphere side used in a dilute chloride ion environment of 1000 ppm or less, the aluminum alloy heat exchanger being formed by brazing a tube and an aluminum fin, the tube being formed of a two-layer aluminum alloy clad tube material of an aluminum alloy core material and a sacrificial anode material clad on a side surface of the core material such that the core material serves as a coolant passage side and the sacrificial anode material serves as the atmosphere side, wherein the core material is formed of an aluminum alloy containing 0.60 to 2.00 mass% of Mn and 1.00 mass% or less of Cu, and optionally further comprising 1.50 mass% or less of Si and / or 0.70 mass% or less of Fe and / or 0.01 to 0.30 mass% of Ti, the remainder being Al and unavoidable impurities, the sacrificial anode material is formed of an aluminum alloy containing 2.50 to 10.00 mass% of Zn and optionally further comprising at least one of 1.50 mass% or less of Si, 1.50 mass% or less of Fe, and 1.50 mass% or less of Mn, the remainder being Al and unavoidable impurities, a pitting corrosion potential of a sacrificial anode material surface of the tube of the aluminum alloy heat exchanger in a 5% NaCl solution is -800 (mV vs. Ag / AgCl) or less and a pitting potential of the aluminum fin of the aluminum alloy heat exchanger in a 5% NaCl solution is smaller than the pitting potential of the sacrificial anode material surface of the tube of the aluminum alloy heat exchanger in a 5% NaCl solution.

Description

TECHNICAL FIELD

[0001] The present invention relates to an aluminum alloy heat exchanger having excellent external surface corrosion resistance in an environment where the atmosphere side is in a dilute chloride ion environment. TECHNICAL BACKGROUND

[0002] In the prior art, aluminum alloy extruded tubes or tubes formed by bending an aluminum alloy plate material are used as coolant passage tubes for aluminum alloy heat exchangers, which are joined and unified by brazing. To improve the corrosion resistance of the outer surface (atmosphere side) of these coolant passage tubes, extruded flat perforated tubes are formed by thermally spraying Zn on the side serving as an outer surface of the coolant passage tubes, and diffusing the thermally sprayed Zn from the surface of the coolant passage tubes by brazing heating to form a Zn diffusion layer.Tubes serving as coolant passage tubes formed by bending a clad plate material for joining by brazing are designed to achieve the sacrificial anode effect with a Zn diffusion layer by plating an Al-Zn-based alloy (a sacrificial anode material).

[0003] In recent years, automotive heat exchangers, in particular, are required to have reduced component thickness and stable, high corrosion resistance in a dilute chloride ion environment, such as condensate and rainwater, as well as in a concentrated chloride ion environment, such as that found in ordinary sea salt particles and / or snow melting agents. Since a CASS test using a 5% NaCl aqueous solution, a SWAAT test using artificial salt water, and the like are conventionally used to evaluate the corrosion resistance of automotive heat exchangers, aluminum materials with good corrosion resistance in these environments, i.e., environments with a high concentration of chloride ions, have been developed.In environments with dilute chloride ions, such as condensate and rainwater, the corrosion mechanism is different from that in environments with high chloride ion concentrations. Therefore, it has become clear that the corrosion resistance of aluminum materials with good corrosion resistance in an environment with high chloride ion concentration is not sufficient in an environment where the atmospheric side is in a dilute chloride ion environment.

[0004] In addition, in conventional extruded pipes, uniform thermal spraying of Zn is difficult, a corrosion rate is high in a part where Zn is thermally sprayed thickly, and the thickness of the sacrificial anode layer after brazing is insufficient in a part where Zn is thermally sprayed thinly. For pipes formed by bending a plate material, if the amount of Zn in the sacrificial anode material is reduced to reduce the corrosion rate, a sufficient potential difference to obtain the sacrificial anode effect cannot be ensured. Therefore, it is difficult to reduce the Zn content of the sacrificial anode material. In addition, with regard to increasing the thickness of the sacrificial anode material, it is difficult to increase the plating ratio from the perspective of manufacturing cost.

[0005] Therefore, some brazing sheets have been proposed. In one proposed brazing sheet, Cu is added to the brazing material on the inner surface in a larger amount than in the core material, so that a potential gradient is obtained such that the potential becomes nobler from the outer surface side to the inner surface side after brazing. In another proposed brazing sheet, Zn is added to the brazing material on the outer surface side, and Cu is added to the brazing material on the inner surface side, so that the potential becomes nobler from the outer surface to the inner surface of the brazing sheet by a concentration gradient of Zn and Cu formed by adjusting Zn and Cu to a specific addition ratio.

[0006] In addition, a plating material has been proposed. In the plating material, the potential is adjusted to become more noble from the outer surface to the inner surface in an aluminum alloy formed of three layers, with an inner plating material plated on a side surface opposite to the sacrificial anode material.

[0007] In addition, an aluminum alloy plating material has been proposed. In the aluminum alloy plating material, the Si content of the layer on the inner surface, which serves as the inner surface of the heat exchanger in contact with the coolant, is set to 1.5% or less to prevent the layer on the inner surface from being melted during brazing. PRINTED STATUS OF TECHNICAL PATENT DOCUMENTS Patent Document 1: Japanese Patent Publication 2011-224656-A Patent Document 2: Japanese Patent Publication 2009-127121-A Patent Document 3: Japanese Patent Publication 2007-247021-A Patent Document 4: Japanese Patent Publication 2008-240084-A Patent Document 5: Japanese Patent Publication 2014-114506-A SUMMARY OF THE INVENTION PROBLEM TO BE SOLVED

[0008] In the conventional methods described above, the layer formed with Cu diffused from the brazing material and exhibiting noble potential is thin, and the potential difference between the layer with the noble potential and the core material is small. Therefore, most of the core material is worn away by corrosion, and the effect of suppressing the occurrence of a through-hole is insufficient in the state immediately before a through-hole is formed.

[0009] In addition, in the conventional method described above, the effect of suppressing the occurrence of a through-hole in an environment where the atmosphere side is in a dilute chloride ion environment is insufficient, solely by the potential difference between the sacrificial anode material and the core material and the potential difference between the core material and the inner cladding material. Since the conductivity of the water film is high in a high ion concentration environment, when the structure is placed in a corrosion environment, the sacrificial anode effect covers a sufficiently distant region, and the corrosion resistance effect is maintained as long as a potential difference between the sacrificial anode material and the core material, which serves as the component whose corrosion is to be prevented, is ensured to a certain extent.However, since the conductivity of the water film is low in a dilute chloride ion environment, when the structure is placed in a corrosion environment, the sacrificial anode effect only covers a very close range, and the corrosion resistance effect is not obtained even if a potential difference between the sacrificial anode material and the core material, which serves as the component to be protected from corrosion, is ensured to a certain extent.

[0010] In addition, in the conventional method described above, the core material has a high Cu content. This structure causes the problem that Cu diffuses into the outer surface layer during brazing heating, reducing the sacrificial anode effect of the outer surface layer, and also causes the problem that the outer surface layer wears faster because the potential of the core material relative to the outer surface layer is too noble.

[0011] Therefore, it is an object of the present invention to provide an aluminum alloy heat exchanger having excellent corrosion resistance of the outer surface in an environment where the atmosphere side of the heat exchanger is in a dilute chloride ion environment. SOLUTION TO THE PROBLEM

[0012] To solve the problem described above, an aluminum alloy heat exchanger having the features of claim 1 and an aluminum alloy heat exchanger having the features of claim 2 are provided. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a schematic sectional view showing a manufacturing example of a tube of an aluminum alloy heat exchanger according to the present invention. Fig.2 is a schematic sectional view showing a manufacturing example of the tube of the aluminum alloy heat exchanger according to the present invention. Fig. 3 is a schematic view showing a part of an embodiment of the aluminum alloy heat exchanger according to the present invention. Fig. 4 is a diagram showing a Zn diffusion state of a sacrificial anode material of the tube after brazing, a Cu diffusion state of a core material layer, and a potential distribution. Fig. 5 is a diagram showing a Zn diffusion state of the sacrificial anode material of the tube after brazing, a Cu diffusion state of the core material layer and an inner cladding material layer, and a potential distribution. EMBODIMENTS

[0013] An aluminum alloy heat exchanger according to a first embodiment of the present invention is an aluminum alloy heat exchanger having an atmosphere side used in a dilute chloride ion environment of 1000 ppm or less, wherein the aluminum alloy heat exchanger is formed by brazing a tube and an aluminum fin, the tube being formed of a two-layer aluminum alloy clad tube material composed of an aluminum alloy core material and a sacrificial anode material plated on a side surface of the core material such that the core material serves as a coolant passage side and the sacrificial anode material serves as the atmosphere side, the core material is formed of an aluminum alloy containing 0.60 to 2.00 mass% of Mn and 1.00 mass% or less of Cu, the remainder being Al and unavoidable impurities, the sacrificial anode material is made of an aluminum alloy containing 2.50 to 10.00 mass% of Zn, the remainder being Al and unavoidable impurities, a pitting corrosion potential of a sacrificial anode material surface of the tube of the aluminum alloy heat exchanger in a 5% NaCl solution is -800 (mV vs. Ag / AgCl) or less and a pitting potential of the aluminum fin of the aluminum alloy heat exchanger in a 5% NaCl solution is smaller than the pitting potential of the sacrificial anode material surface of the tube of the aluminum alloy heat exchanger in a 5% NaCl solution.

[0014] The aluminum alloy heat exchanger according to the first embodiment of the present invention is an aluminum alloy heat exchanger with an atmosphere side used in a dilute chloride ion environment of 1000 ppm or less. The aluminum alloy heat exchanger according to the first embodiment of the present invention is obtained by brazing a tube serving as a formed member made of an aluminum alloy clad tube material and an aluminum fin.

[0015] In the aluminum alloy heat exchanger according to the first embodiment of the present invention, the aluminum alloy clad tube material to be formed into a tube shape is a two-layer aluminum alloy clad material formed of an aluminum alloy core material and a sacrificial anode material plated on a side surface of the core material.

[0016] The core material of the two-layer aluminum alloy clad pipe material is formed by an aluminum alloy containing 0.60 to 2.00 mass% of Mn and 1.00 mass% or less of Cu, the balance being Al and unavoidable impurities.

[0017] Mn in the core material improves the strength of the core material and adjusts the pitting corrosion potential of the core material to be noble. The Mn content of the core material of the two-layer aluminum alloy clad pipe material is 0.60 to 2.00 mass%, preferably 1.00 to 2.00 mass%. If the Mn content of the core material is less than the above-described range, the effect of Mn is insufficient. An Mn content exceeding the above-described range causes difficulty in rolling the clad material.

[0018] Cu in the core material serves to adjust the pitting potential of the core material to a noble (high) potential and is included to regulate the balance of the pitting potential with respect to the sacrificial anode material. Cu in the core material diffuses into the sacrificial anode material during brazing heating, so the potential difference with respect to the sacrificial anode material decreases and the corrosion rate of the sacrificial anode material increases. Therefore, the Cu content of the core material of the two-layer aluminum alloy clad tube material is 1.00 mass% or less.

[0019] The core material of the two-layer aluminum alloy clad tube material may further contain Si. Si in the core material serves to improve the strength of the core material. The Si content of the core material of the two-layer aluminum alloy clad tube material is 1.50 mass% or less, preferably 0.90 mass% or less. If the Si content of the core material exceeds the above-described range, the melting point of the core material decreases, and the core material is easily melted during brazing.

[0020] The core material of the two-layer aluminum alloy clad pipe material may further contain Fe. Fe serves to improve the strength of the core material. The Fe content of the core material of the two-layer aluminum alloy clad pipe material is 0.70 mass% or less. If the Fe content of the core material exceeds the above-described range, the self-corrosion rate of the core material increases.

[0021] The core material of the two-layer aluminum alloy clad pipe material may further include Ti. Ti is divided into high-concentration regions and low-concentration regions in the thickness direction of the core material, forming a layered structure in which the high-concentration regions and low-concentration regions are alternately distributed, and the low-Ti concentration regions corrode more strongly than the high-Ti concentration regions. Consequently, Ti causes the corrosion form of the core material to have a layered form and prevents corrosion from progressing in the thickness direction of the pipe, thus improving corrosion resistance. The Ti content of the core material of the two-layer aluminum alloy clad pipe material is 0.01 to 0.30 mass%. If the Ti content of the core material is less than the above-described range, the effect of Ti is insufficient.If the Ti content exceeds the range described above, a huge crystallized substance will be generated and the formability of the pipe will be deteriorated.

[0022] The core material of the two-layer aluminum alloy clad pipe material may contain V, Cr, Zr, or B at 0.30 mass% or less within the range that does not impair the effect of the present invention.

[0023] The sacrificial anode material of the two-layer aluminum alloy clad tube material is made of aluminum alloy containing 2.50 to 10.00 mass% of Zn, the balance being Al and unavoidable impurities.

[0024] Zn in the sacrificial anode material serves to adjust the pitting potential of the sacrificial anode material to a less noble (lower) potential, and is included to regulate the balance of the pitting potential with respect to the core material and maintain the surface pitting potential of the sacrificial anode material at a low potential after brazing heating. The Zn content of the sacrificial anode material of the two-layer aluminum alloy clad tube material is 2.50 to 10.00 mass%, preferably 3.50 to 10.00 mass%, more preferably 4.50 to 10.00 mass%. If the Zn content of the sacrificial anode material is less than the above-described range, the pitting potential of the sacrificial anode material surface in a 5% NaCl solution will not be -800 (mV vs. Ag / AgCl) or less.When the Zn content exceeds the range described above, the pitting potential of the sacrificial anode material surface in a 5% NaCl solution becomes much less noble, the self-corrosion rate of the sacrificial anode material increases, and the corrosion resistance life is shortened.

[0025] The sacrificial anode material of the two-layer aluminum alloy clad tube material may further contain Si. Si serves to improve the strength of the sacrificial anode material. The Si content of the sacrificial anode material of the two-layer aluminum alloy clad tube material is 1.50 mass% or less, preferably 0.50 mass% or less. If the Si content of the sacrificial anode material exceeds the above-described range, the self-corrosion rate of the sacrificial anode material increases.

[0026] The sacrificial anode material of the two-layer aluminum alloy clad tube material may further contain Fe. Fe serves to improve the strength of the sacrificial anode material. The Fe content of the sacrificial anode material of the two-layer aluminum alloy clad tube material is 1.50 mass% or less. If the Fe content of the sacrificial anode material exceeds the above-described range, the self-corrosion rate of the sacrificial anode material increases.

[0027] The sacrificial anode material of the two-layer aluminum alloy plating material may further contain Mn. Mn serves to improve the strength of the sacrificial anode material. The Mn content of the sacrificial anode material of the two-layer aluminum alloy plating tube material is 1.50 mass% or less, preferably 0.50 mass% or less. When the Mn content of the sacrificial anode material exceeds the above-described range, the self-corrosion rate of the sacrificial anode material increases, and the surface pitting potential of the sacrificial anode material becomes noble.

[0028] The sacrificial anode material of the two-layer aluminum alloy clad tube material may contain In, Sn, Ti, V, Cr, Zr, or B at 0.30 mass% or less within the range that does not impair the effect of the present invention.

[0029] In the two-layer aluminum alloy clad pipe material, with respect to the Si content and the Fe content of each of the sacrificial anode material and the pipe material, use of high-purity metal causes an increase in manufacturing cost, and it is not preferable that the Si content and the Fe content are each set to less than 0.03%.

[0030] In the two-layer aluminum alloy clad pipe material, when the thickness thereof is 0.5 mm or less, the plating ratio of the sacrificial anode material is preferably 5 to 30%, more preferably 10 to 30%. If the plating ratio of the sacrificial anode material is smaller than the above-described range, the amount of Zn in the sacrificial anode material decreases due to diffusion during brazing, the pitting potential of the surface of the sacrificial anode material increases, and it becomes difficult to obtain a sufficient sacrificial anode effect. In addition, if the plating ratio of the sacrificial anode material exceeds the above-described range, rolling of the plating material becomes difficult. Furthermore, in the two-layer aluminum alloy clad pipe material, when the thickness thereof exceeds 0.5 mm, the plating ratio of the sacrificial anode material is preferably 3 to 30%.

[0031] The aluminum fin of the aluminum alloy heat exchanger according to the first embodiment of the present invention is made of aluminum and is a formed member made of plate-shaped aluminum. A structure obtained by processing plate-shaped aluminum into a corrugated shape and formed into a fin shape is used as the aluminum fin. The material of the aluminum fin is pure aluminum or an aluminum alloy. An example of the aluminum fin material is a brazing sheet formed of a bare material, a core material made of aluminum or an aluminum alloy, and brazing materials plated on both side surfaces of the core material.The element contained in the aluminum fin is appropriately selected such that the pitting potential of the aluminum fin of the aluminum alloy heat exchanger in a 5% NaCl solution is lower than the pitting potential of the sacrificial anode material surface of the tube of the aluminum alloy heat exchanger in a 5% NaCl solution. For example, containing a lot of Zn in the aluminum alloy constituting the aluminum fin makes it possible to adjust the pitting potential of the aluminum fin to be less noble in a 5% NaCl solution. The Zn content of the aluminum alloy constituting the aluminum fin is preferably 10 mass% or less. Adding a lot of Cu or Mn to the aluminum alloy constituting the aluminum fin makes it possible to adjust the pitting potential of the aluminum fin to be noble in a 5% NaCl solution.The Cu content of the aluminum alloy constituting the aluminum fin is preferably 1.00 mass% or less, and the Mn content is preferably 2.00 mass% or less. When the pitting potential of the aluminum fin in a 5% NaCl solution is lower than the pitting potential of the sacrificial anode material surface of the tube in a 5% NaCl solution, the aluminum alloy constituting the aluminum fin may further contain one or more of 2.00 mass% or less of Si, 2.00 mass% or less of Fe, 0.50 mass% or less of Mg, 0.30 mass% or less of Cr, 0.30 mass% or less of Ti, and 0.30 mass% or less of Zr.

[0032] The aluminum alloy heat exchanger according to the first embodiment of the present invention is a heat exchanger obtained by forming the two-layer aluminum alloy clad tube material in the shape of a tube so that the core material serves as the coolant passage side and the sacrificial anode material serves as the atmosphere side (outer surface), and mounting and joining the aluminum fin by brazing on the outside (atmosphere side) of the tube or on the outside and the inside (coolant passage side).

[0033] Examples of the method for manufacturing a pipe component 1 include a method of forming the two-layer aluminum alloy clad material 2 in the shape of a pipe, then inserting an inner fin 3 formed of a brazing sheet in which brazing materials are arranged on both side surfaces, and making a joint 4 of the pipe 1 with a brazing material of the inner fin 3 by brazing, as shown in Fig. 1, and a method of applying a pasty brazing filler metal 5 to the sacrificial anode material side of the two-layer aluminum alloy plating material 2 in advance, forming the two-layer aluminum alloy plating material 2 in the shape of a tube, or applying the pasty brazing filler metal 5 after forming the two-layer aluminum alloy plating material 2 in the shape of a tube, and making the joint 4 with the pasty brazing filler metal 5 by brazing, as shown in Fig. 2 shown.

[0034] The aluminum alloy heat exchanger according to the first embodiment of the present invention is manufactured by forming the two-layer aluminum alloy tube material in the shape of a tube such that the core material forms the coolant passage side and the sacrificial anode material serves as the atmosphere side (outer surface), and mounting the aluminum fin on the atmosphere side of the tube, applying, for example, a fluoride-based flux thereto, then brazing the structure for three minutes at a temperature of 600°C in an inert gas atmosphere furnace, and joining the tube to the aluminum fin. For example, in Fig.3 shows an aluminum alloy heat exchanger 10 by alternately stacking and assembling the tubes 1, which are formed by forming the two-layer aluminum alloy tube material according to the present invention in the shape of a tube so that a sacrificial anode material surface 12 serves as an outer surface (atmosphere side), and aluminum fins 11. When each of the aluminum fins is a brazing sheet, the aluminum fins formed in a fin shape are used without processing, and the aluminum fins and the tubes are joined by brazing. When each of the aluminum fins is a bare material, a pasty brazing filler metal is applied to the surface on the sacrificial anode material side of the tube to be joined to the aluminum fin by brazing, and the fin formed in the shape of a fin is joined to the tube by brazing. Fig.3 is a schematic perspective view showing a part of an embodiment of the aluminum alloy heat exchanger according to the present invention.

[0035] In addition, in the aluminum alloy heat exchanger according to the first embodiment of the present invention, the pitting potentials of the sacrificial anode material and the core material of the assembled tube component satisfy the relationship "pitting potential of the sacrificial anode material < pitting potential of the core material." Since the sacrificial anode material exhibits the sacrificial anode effect for the core material, an improvement in corrosion resistance of the outer surface (atmosphere side) in an ordinary corrosion environment is achieved by means of the sacrificial anode layer.

[0036] In addition, in the aluminum alloy heat exchanger according to the first embodiment of the present invention, the pitting potential of the sacrificial anode material surface of the tube and the pitting potential of the aluminum fin satisfy the relationship “pitting potential of the sacrificial anode material surface of the tube ≤ -800 (mV vs. Ag / AgCl)” and the relationship “pitting potential of the sacrificial anode material surface of the tube > pitting potential of the aluminum fin”. Since the aluminum alloy heat exchanger according to the first embodiment of the present invention satisfies the relationship “pitting potential of the sacrificial anode material surface of the tube ≤ -800 (mV vs.By satisfying the relationship "pitting potential of the sacrificial anode material surface of the tube > pitting potential of the aluminum fin," the entire corrosion potential is maintained at a potential lower than the pitting potential of the sacrificial anode material surface of the tube, and corrosion occurring in the tube surface is suppressed. This structure suppresses the generation of a through-hole on the atmosphere side in a dilute chloride ion environment and improves the corrosion resistance of the outer surface (atmosphere side) in a dilute chloride ion environment.

[0037] The aluminum heat exchanger according to the second embodiment of the present invention is an aluminum alloy heat exchanger having an atmosphere side used in a dilute chloride ion environment of 1000 ppm or less, wherein the aluminum alloy heat exchanger is formed by brazing a tube and an aluminum fin, the tube being formed of a three-layer aluminum alloy clad tube material made of an aluminum alloy core material, a sacrificial anode material clad on one side surface of the core material, and an inner clad material clad on the other side surface of the core material such that the inner clad material serves as a coolant passage side and the sacrificial anode material serves as the atmosphere side, in which the core material is formed of an aluminum alloy containing 0.60 to 2.00 mass% of Mn and 0.60 mass% or less of Cu, the remainder being Al and unavoidable impurities, the sacrificial anode material is made of an aluminum alloy containing 2.50 to 10.00 mass% of Zn, the remainder being Al and unavoidable impurities, the inner plating material is formed of an aluminum alloy containing 0.60 to 2.00 mass% of Mn and 0.20 to 1.50 mass% of Cu, the remainder being Al and unavoidable impurities, a difference (YX) between a Cu content (Y) of the inner cladding material of the three-layer aluminum alloy cladding tube material and a Cu content (X) of the core material of the three-layer aluminum alloy cladding tube material is greater than 0.00 mass%, a pitting corrosion potential of the sacrificial anode material surface of the aluminum alloy heat exchanger tube in a 5% NaCl solution is -800 (mV vs. Ag / AgCl) or less, and a pitting corrosion potential of the aluminum fin of the aluminum alloy heat exchanger in a 5% NaCl solution is smaller than the pitting corrosion potential of the sacrificial anode material surface of the tube of the aluminum alloy heat exchanger in a 5% NaCl solution.

[0038] The aluminum heat exchanger according to the second embodiment of the present invention is an aluminum alloy heat exchanger with an atmosphere side used in a dilute chloride ion environment of 1000 ppm or less. The aluminum alloy heat exchanger according to the second embodiment of the present invention is formed by brazing a tube serving as a formed member made of an aluminum alloy clad tube material and an aluminum fin.

[0039] In the aluminum heat exchanger according to the second embodiment of the present invention, the aluminum alloy clad tube material formed in the shape of a tube is a three-layer aluminum alloy clad material composed of an aluminum alloy core material, a sacrificial anode material clad on one side surface of the core material, and an inner clad material clad on the other side surface of the core material.

[0040] The core material of the three-layer aluminum alloy clad pipe material is made of aluminum alloy containing 0.60 to 2.00 mass% of Mn and 0.60 mass% or less of Cu, the balance being Al and unavoidable impurities.

[0041] Mn in the core material improves the strength of the core material and adjusts the pitting corrosion potential of the core material to be noble. The Mn content of the core material of the three-layer aluminum alloy clad pipe material is 0.60 to 2.00 mass%, preferably 1.00 to 2.00 mass%. If the Mn content of the core material is less than the above-described range, the effect of Mn is insufficient. The Mn content exceeding the above-described range makes rolling of the clad material difficult.

[0042] Cu in the core material is included to regulate the potential balance between the inner cladding material and the core material. Cu in the core material diffuses into the sacrificial anode material during brazing heating, so that the potential difference with respect to the sacrificial anode material is reduced and the corrosion rate of the sacrificial anode material increases. For this reason, the Cu content of the core material of the three-layer aluminum alloy clad tube material is 1.00 mass% or less, preferably 0.40 mass% or less, and smaller than the Cu content of the inner cladding material, more preferably less than 0.05 mass%.

[0043] The core material of the three-layer aluminum alloy clad tube material may further contain Si. Si in the core material serves to improve the strength of the core material. The Si content of the core material of the three-layer aluminum alloy clad tube material is 1.50 mass% or less, preferably 0.90 mass% or less. If the Si content of the core material exceeds the above-described range, the melting point of the core material decreases, and the core material is easily melted during brazing.

[0044] The core material of the three-layer aluminum alloy clad pipe material may further contain Fe. Fe serves to improve the strength of the core material. The Fe content of the core material of the three-layer aluminum alloy clad pipe material is 0.70 mass% or less. If the Fe content of the core material exceeds the range described above, the self-corrosion rate of the core material increases.

[0045] The core material of the three-layer aluminum alloy clad pipe material may further include Ti. Ti is divided into high-concentration regions and low-concentration regions in the thickness direction of the pipe core material, forming a layered structure in which the high-concentration regions and low-concentration regions are alternately distributed. Low Ti concentration regions corrode preferentially over high Ti concentration regions. Therefore, Ti causes the corrosion form of the core material to have a layered form and prevents corrosion of the core material from progressing in the thickness direction of the pipe, thus improving corrosion resistance. The Ti content of the core material of the three-layer aluminum alloy clad material is 0.01 to 0.30 mass%.If the Ti content of the core material is less than the above range, the effect of Ti is insufficient. If the Ti content exceeds the above range, a huge crystallized substance will be generated, and the formability of the tube will deteriorate.

[0046] The core material of the three-layer aluminum alloy clad material may contain V, Cr, Zr, or B at 0.30 mass% or less within the range that does not impair the effects of the present invention.

[0047] The sacrificial anode material of the three-layer aluminum alloy clad tube material is made of aluminum alloy with 2.50 to 10.00 mass% of Zn, the balance being Al and unavoidable impurities.

[0048] Zn in the sacrificial anode material serves to adjust the potential of the sacrificial anode material to a less noble (low) potential, and is included to regulate the balance of the pitting potential with respect to the core material and the inner cladding material, and to maintain the surface pitting potential of the sacrificial anode material of the tube at a low potential after brazing heating. The Zn content of the sacrificial anode material of the three-layer aluminum alloy cladding tube material is 2.50 to 10.00 mass%, preferably 3.50 to 10.00 mass%, more preferably 4.50 to 10.00 mass%. If the Zn content of the sacrificial anode material is less than the above-described range, the effect of Zn is insufficient. When the Zn content exceeds the range described above, the self-corrosion rate of the sacrificial anode material increases and the corrosion resistance life is shortened.

[0049] The sacrificial anode material of the three-layer aluminum alloy clad tube material may further contain Si. Si serves to improve the strength of the sacrificial anode material. The Si content of the sacrificial anode material of the three-layer aluminum alloy clad tube material is 1.50 mass% or less, preferably 0.50 mass% or less. If the Si content of the sacrificial anode material exceeds the above-described range, the self-corrosion rate of the sacrificial anode material increases.

[0050] The sacrificial anode material of the three-layer aluminum alloy clad tube material may further contain Fe. Fe serves to improve the strength of the sacrificial anode material. The Fe content of the sacrificial anode material of the three-layer aluminum alloy clad tube material is 1.50 mass% or less. If the Fe content of the sacrificial anode material exceeds the above-described range, the self-corrosion rate of the sacrificial anode material increases.

[0051] The sacrificial anode material of the three-layer aluminum alloy clad tube material may further contain Mn. Mn serves to improve the strength of the sacrificial anode material. The Mn content of the sacrificial anode material of the three-layer aluminum alloy clad tube material is 1.50 mass% or less, preferably 0.50 mass% or less. When the Mn content of the sacrificial anode material exceeds the above-described range, the self-corrosion rate of the sacrificial anode material increases, and the surface pitting potential of the sacrificial anode material becomes noble.

[0052] The sacrificial anode material of the three-layer aluminum alloy clad tube material may contain 0.30 mass% or less of In, Sn, Ti, V, Cr, Zr, or B within the range that does not impair the effects of the present invention.

[0053] The inner cladding material of the three-layer aluminum alloy cladding pipe material is made of aluminum alloy containing 0.60 to 2.00 mass% of Mn and 0.20 to 1.50 mass% of Cu, the balance being Al and unavoidable impurities.

[0054] Mn in the inner cladding material improves the strength of the inner cladding material and adjusts the pitting corrosion potential of the inner cladding material to be noble. The Mn content of the inner cladding material of the three-layer aluminum alloy clad pipe material is 0.60 to 2.00 mass%, preferably 1.00 to 2.00 mass%. If the Mn content of the inner cladding material is less than the above-described range, the effect of Mn is insufficient. If the Mn content exceeds the above-described range, rolling of the cladding material becomes difficult.

[0055] Cu in the core material serves to adjust the potential of the inner cladding material to a noble (high) potential and is included to regulate the potential balance with respect to the core material. The Cu content of the inner cladding material of the three-layer aluminum alloy cladding tube material is 0.20 to 1.50 mass%, preferably 0.20 to 1.00 mass%. If the Cu content of the inner cladding material is less than the above-described range, the effect of Cu is insufficient. If the Cu content exceeds the above-described range, the melting point of the inner cladding material decreases, and the inner cladding material is easily melted during brazing.

[0056] A difference (YX) between the Cu content (Y) of the inner clad material of the three-layer aluminum alloy clad pipe material and the Cu content (X) of the core material of the three-layer aluminum alloy clad pipe material is greater than 0.00 mass%, preferably greater than 0.00 mass% and less than or equal to 0.40 mass%.

[0057] The inner cladding material of the three-layer aluminum alloy clad tube material may further contain Si. Si serves to improve the strength of the inner cladding material. The Si content of the inner cladding material of the three-layer aluminum alloy clad tube material is 1.50 mass% or less, preferably 0.90 mass% or less. If the Si content of the inner cladding material exceeds the above-described range, the melting point of the inner cladding material decreases, and the inner cladding material is easily melted during brazing.

[0058] The inner cladding material of the three-layer aluminum alloy clad pipe material may further contain Fe. Fe serves to improve the strength of the inner cladding material. The Fe content of the inner cladding material of the three-layer aluminum alloy clad pipe material is 0.70 mass% or less. If the Fe content of the inner cladding material exceeds 0.70 mass%, the self-corrosion rate of the inner cladding material increases.

[0059] The inner cladding material of the three-layer aluminum alloy clad pipe material may further include Ti. Ti is divided into high-concentration regions and low-concentration regions in the thickness direction of the inner cladding material, forming a layered structure in which the high-concentration regions and low-concentration regions are alternately distributed, and the low-Ti concentration regions corrode preferentially over the high-Ti concentration regions. Accordingly, Ti causes the corrosion form of the core material to have a layered form and prevents corrosion from progressing in the thickness direction of the pipe, thus improving corrosion resistance of the pipe. The Ti content of the inner cladding material of the three-layer aluminum alloy clad pipe material is 0.01 to 0.30 mass%.If the Ti content of the inner cladding material exceeds the range described above, a huge crystallized substance will be generated and the formability of the pipe will be deteriorated.

[0060] The inner clad material of the three-layer aluminum alloy clad pipe material may contain 0.30 mass% or less of V, Cr, Zr, or B within the range that does not impair the effects of the present invention.

[0061] In the three-layer aluminum alloy clad pipe material, with respect to the Si content and the Fe content of the sacrificial anode material, the core material, and the inner clad material, using a high-purity metal causes an increase in manufacturing cost, and it is not preferable to set the Si content and the Fe content to be less than 0.03% each.

[0062] For the three-layer aluminum alloy clad pipe material, when the thickness thereof is 0.5 mm or less, the plating ratio of the sacrificial anode material is preferably 5 to 30%, more preferably 10 to 30%. If the plating ratio of the sacrificial anode material is smaller than the above-described range, the amount of Zn in the sacrificial anode material decreases due to diffusion during brazing, the pitting potential of the surface of the sacrificial anode material increases, and it becomes difficult to obtain a sufficient sacrificial anode effect. In addition, if the plating ratio of the sacrificial anode material exceeds the above-described range, rolling of the clad material becomes difficult. Furthermore, for the three-layer aluminum alloy clad pipe material, when the thickness thereof exceeds 0.5 mm, the plating ratio of the sacrificial anode material is preferably 3 to 30%.

[0063] In the three-layer aluminum alloy clad pipe material, when the thickness thereof is 0.5 mm or less, the plating ratio of the inner plating material is preferably 5 to 30%, more preferably 10 to 30%. If the plating ratio of the inner plating material is smaller than the above-described range, the Cu concentration in the inner plating material is reduced due to diffusion during brazing, the potential difference with respect to the core material decreases, and it becomes difficult to obtain the sacrificial anode effect of the core material. In addition, if the plating ratio of the inner plating material exceeds the above-described range, rolling of the plating material becomes difficult. Furthermore, in the three-layer aluminum alloy clad pipe material, when the thickness thereof exceeds 0.5 mm, the plating ratio of the inner plating material is preferably 3 to 30%.

[0064] The aluminum fin of the aluminum alloy heat exchanger according to the second embodiment of the present invention is made of aluminum and is a formed member made of plate-shaped aluminum. A structure obtained by processing plate-shaped aluminum to be corrugated and formed into a fin shape is used as the aluminum fin. The material of the aluminum fin is pure aluminum or an aluminum alloy. An example of the aluminum fin material is a brazing sheet formed of a bare material, a core material made of aluminum or an aluminum alloy, and brazing materials clad on both sides of the core material.The element contained in the aluminum fin is appropriately selected such that the pitting potential of the aluminum fin of the aluminum alloy heat exchanger in a 5% NaCl solution is lower than the pitting potential of the sacrificial anode material surface of the tube of the aluminum alloy heat exchanger in a 5% NaCl solution. For example, a high content of Zn in the aluminum alloy constituting the aluminum fin makes it possible to adjust the pitting potential of the aluminum fin in a 5% NaCl solution to be less noble. The Zn content of the aluminum alloy constituting the aluminum fin is preferably 10.00 mass% or less. The presence of a large amount of Cu or Mn in the aluminum alloy constituting the aluminum fin makes it possible to adjust the pitting potential of the aluminum fin in a 5% NaCl solution to be noble.The Cu content of the aluminum alloy constituting the aluminum fin is preferably 1.00 mass% or less, and the Mn content is preferably 2.00 mass% or less. When the pitting potential of the aluminum fin in a 5% NaCl solution is lower than the pitting potential of the sacrificial anode material surface of the tube in a 5% NaCl solution, the aluminum alloy constituting the aluminum fin may further contain one or more of 2.00 mass% or less of Si, 2.00 mass% or less of Fe, 0.50 mass% or less of Mg, 0.30 mass% or less of Cr, 0.30 mass% or less of Ti, and 0.30 mass% or less of Zr.

[0065] The aluminum alloy heat exchanger according to the second embodiment of the present invention is a heat exchanger obtained by forming the three-layer aluminum alloy clad tube material in the shape of a tube so that the inner clad material serves as the coolant passage side and the sacrificial anode material serves as the atmosphere side (outer surface), and mounting and joining the aluminum fin by brazing on the outer side (atmosphere side) of the tube or on the outer side and the inner side (coolant passage side).

[0066] The method for manufacturing the tube of the aluminum alloy heat exchanger according to the second embodiment of the present invention is similar to the method for manufacturing the tube of the aluminum alloy heat exchanger according to the first embodiment of the present invention.

[0067] The aluminum alloy heat exchanger according to the second embodiment of the present invention is manufactured by forming the three-layer aluminum alloy clad tube material into a tube shape such that the inner clad material serves as the coolant passage side and the sacrificial anode material serves as the atmosphere side (outer surface), mounting the aluminum fin on the outer surface (atmosphere side) of the tube, for example, applying a fluoride-based flux thereto, then brazing the structure for three minutes at a temperature of 600°C in an inert gas atmosphere furnace, and joining the tube to the aluminum fin. The method for manufacturing the aluminum alloy heat exchanger according to the second embodiment of the present invention is similar to the method for manufacturing the aluminum alloy heat exchanger according to the first embodiment of the present invention.

[0068] In addition, in the aluminum alloy heat exchanger according to the second embodiment of the present invention, the pitting potentials of the sacrificial anode material, the core material, and the inner cladding material of the assembled tube component are such that the relationship "pitting potential of the sacrificial anode material < pitting potential of the core material < pitting potential of the inner cladding material" is satisfied. Since the sacrificial anode material has the sacrificial anode effect for the core material, and the core material has the sacrificial anode effect for the inner cladding material, an improvement in corrosion resistance of the outer surface (atmosphere side) in an ordinary corrosion environment is obtained with each of the sacrificial anode layers.

[0069] In addition, in the aluminum alloy heat exchanger according to the second embodiment of the present invention, the pitting potential of the sacrificial anode material surface of the tube and the pitting potential of the aluminum fin satisfy the relationship “pitting potential of the sacrificial anode material surface of the tube ≤ -800 (mV vs. Ag / AgCl)” and the relationship “pitting potential of the sacrificial anode material surface of the tube > pitting potential of the aluminum fin”. Since the aluminum alloy heat exchanger according to the second embodiment of the present invention satisfies the relationship “pitting potential of the sacrificial anode material surface of the tube ≤ -800 (mV vs.By satisfying the relationship "pitting potential of the sacrificial anode material surface of the tube > pitting potential of the aluminum fin," the corrosion potential of the entire heat exchanger is maintained at a potential lower than the pitting potential of the sacrificial anode material surface of the tube, and corrosion on the tube surface is suppressed. This structure suppresses the generation of a through-hole on the atmosphere side in a dilute chloride ion environment and improves the corrosion resistance of the outer surface (atmosphere side) in a dilute chloride ion environment.

[0070] The following explains a comparison of examples of the present invention with comparative examples to demonstrate the effect thereof. These examples illustrate one embodiment of the present invention, and the present invention is not limited thereto. EXAMPLESExample 1

[0071] A sacrificial anode material alloy, a core material alloy, and an inner cladding material alloy with compositions shown in Table 1 were cast into ingots by semi-continuous casting. For the obtained ingots, the sacrificial anode material alloy ingot was homogenized at 500°C for 8 hours and then hot-rolled to a predetermined thickness at a starting temperature of 500°C. The core material alloy ingot and the inner cladding material alloy ingot were homogenized at 500°C for 8 hours, after which the core material alloy ingot was machined, and the inner cladding material alloy ingot was hot-rolled to a predetermined thickness at a starting temperature of 500°C.

[0072] Next, the hot-rolled components of the sacrificial anode material alloy and the inner cladding material alloy were machined, and then the respective aluminum alloys were stacked in combinations shown in Table 1. Each of the stacked structures was hot-rolled at a starting temperature of 500°C to a thickness of 3 mm, then cold-rolled and subjected to intermediate annealing at a temperature of 400°C. After that, the structures were cold-rolled to obtain aluminum alloy cladding plate materials (test pieces 1 to 109) with a thickness of 0.2 mm.

[0073] Next, a core material alloy ingot and a brazing material alloy ingot with compositions shown in Table 1 were cast by semi-continuous casting. The brazing material alloy ingot of the aluminum fin material was homogenized at 500°C for one hour and then hot-rolled to a predetermined thickness at a starting temperature of 500°C. The core material alloy ingot of the aluminum fin material was homogenized at 500°C for eight hours, after which the surfaces of the core material alloy ingot on which the brazing material alloy ingot was to be stacked were machined. After that, the brazing material alloy ingots were stacked on both sides of the core material alloy ingot of the aluminum fin material. Each of the stacked structures was hot-rolled at a starting temperature of 500°C to obtain a clad material with a predetermined thickness.Subsequently, each of the cladding materials was cold-rolled and subjected to intermediate annealing at a temperature of 400°C. The cladding materials were then cold-rolled to obtain aluminum fin materials with a thickness of 0.08 mm. The composition of the brazing alloy ingot of the aluminum fin material was set to an aluminum alloy containing 10.00 mass% of Si, with the remainder being Al and unavoidable impurities, and the brazing alloy plating ratio was set to 10% for one side surface. Comparison example 1

[0074] A sacrificial anode material alloy, a core material alloy, and an inner cladding material alloy with compositions shown in Table 2 were cast into ingots by semi-continuous casting. For the ingots, the sacrificial anode material alloy ingot was homogenized at 500°C for eight hours and then hot-rolled to a predetermined thickness at a starting temperature of 500°C. The core material alloy ingot and the inner cladding material alloy ingot were homogenized at 500°C for eight hours, after which the core material alloy ingot was machined, and the inner cladding material alloy ingot was hot-rolled to a predetermined thickness at a starting temperature of 500°C.

[0075] Next, the hot-rolled components of the sacrificial anode material alloy and the inner cladding material alloy were cut to a predetermined size, and the aluminum alloys were stacked in combinations shown in Table 2. Each of the stacked structures was hot-rolled at a starting temperature of 500°C to a thickness of 3 mm, then cold-rolled and subjected to intermediate annealing at a temperature of 400°C. After that, the structures were cold-rolled to obtain aluminum alloy cladding plate materials (test pieces 201 to 220) with a thickness of 0.2 mm.

[0076] Next, a core material alloy ingot and a brazing material alloy ingot with compositions shown in Table 2 were cast by semi-continuous casting. The brazing material alloy ingot of the aluminum fin material was homogenized at 500°C for one hour and then hot-rolled to a predetermined thickness at a starting temperature of 500°C. The core material alloy ingot of the aluminum fin material was homogenized at 500°C for eight hours, after which the surfaces of the core material alloy ingot on which the brazing material alloy ingot was to be stacked were machined. After that, the brazing material alloy ingots were stacked on both sides of the core material alloy ingot of the aluminum fin material. Each of the stacked structures was hot-rolled at a starting temperature of 500°C to obtain a clad material with a predetermined thickness.Subsequently, each of the cladding materials was cold-rolled and subjected to intermediate annealing at a temperature of 400°C. The cladding materials were then cold-rolled to obtain aluminum fin materials with a thickness of 0.08 mm. The composition of the brazing alloy ingot of the aluminum fin material was set to an aluminum alloy containing 10.00 mass% Si, the balance being Al and unavoidable impurities, and the brazing alloy plating ratio was set to 10% per side surface.

[0077] The obtained test pieces were heated at 600°C for three minutes, equivalent to brazing, and subjected to a tensile strength test. In addition, each of the obtained test pieces was formed into a tube with the sacrificial anode material positioned on the outer surface, aluminum fins were mounted between the formed tubes, and a tank and the like were formed and mounted on each of the structures. Thereafter, the structures were subjected to brazing at a temperature of 585 to 630°C for 1 to 30 minutes and subjected to potential measurement and a corrosion test by the following methods. Table 3 and Table 4 show the test results. Tensile strength test

[0078] The test pieces were formed into test pieces according to JIS-5 and subjected to a tensile strength test according to JIS Z2241. Test pieces with a tensile strength of 70 MPa or more were rated as passing the test. Potential measurement

[0079] The pitting corrosion potential of each test piece was measured in a 5% NaCl aqueous solution at room temperature. The surface potential of the sacrificial anode material was measured with the parts of the test piece except the sacrificial anode material-side surface masked. The potential of the core material was measured by masking the parts except the core material surface when no inner plating material was present in the test piece. When the inner plating material was present in the test piece, the test piece was ground from the sacrificial anode material surface side toward the center of the core material thickness, and measurement was performed in a state where the parts except the ground surface were masked. The potential of the inner plating material was measured with the parts except the area on the inner plating material side masked. Corrosion test

[0080] Each of the test pieces was formed into a tube shape in a state where the sacrificial anode material of the test piece was positioned as the outer surface. Aluminum fins were mounted between the formed tubes, and a tank and the like were formed and mounted on each of the structures. After applying a fluoride-based flux to each of the structures, the structures were subjected to brazing at 600°C for three minutes to obtain heat exchangers. From the respective obtained heat exchangers, only the aluminum fin and the sacrificial anode material surface bonded to the aluminum fin were exposed by masking to obtain a test piece. Each of the obtained test pieces was subjected to a spray cycle test according to ASTM G85 to evaluate corrosion resistance.In the splash test, an aqueous solution obtained by mixing 100 ppm NaCl, 100 ppm HCO3, and 100 ppm Na2SO4 with a pH adjusted to 3 was used to simulate a dilute chloride ion environment. Among the test pieces, those in which no through-hole was generated in the pipe at the point where 2500 hours had passed and the corrosion depth was less than 0.10 mm were evaluated as excellent (00) pieces; those in which no through-hole was generated after 2500 hours but the corrosion depth was greater than or equal to 0.10 mm were evaluated as good (0) pieces; and those in which a through-hole was generated before 2500 hours had passed were evaluated as poor (x) pieces. Where, 100 ppm NaCl is an environment corresponding to a chloride ion concentration of 60 ppm.

[0081] As shown in Table 3, each of test pieces 1 to 109 of the examples exhibited a tensile strength of 70 MPa or more after heating equivalent to brazing. For each of the heat exchanger test pieces obtained by combining and brazing test pieces 1 to 109 with the aluminum fins, the pitting potential of the sacrificial anode material surface of the tube and the pitting potential of the aluminum fin satisfied the relationship "pitting potential of the sacrificial anode material surface of the tube ≤ -800 (mV vs. Ag / AgCl)" and the relationship "pitting potential of the sacrificial anode material surface of the tube > pitting potential of the aluminum fin," and no through hole was generated in the corrosion test.

[0082] In contrast, as shown in Table 4, in test piece 201 of the comparative example, since the Zn concentration in the sacrificial anode material was low, the pitting potential of the sacrificial anode material surface after brazing exceeded -800 mV, and the sacrificial anode effect was insufficient. Consequently, in test piece 201, a through hole was generated in the tube in the corrosion test. In test piece 202, since the Zn concentration of the sacrificial anode material was high and the pitting potential of the sacrificial anode material surface was less than or equal to the pitting potential of the aluminum fin, the self-corrosion rate of the aluminum fin increased after brazing, and a through hole was generated in the tube in the corrosion test.In test piece 203, since the Si concentration in the sacrificial anode material was high, the self-corrosion rate of the sacrificial anode material after brazing was high, and a through hole was generated in the tube in the corrosion test. In test piece 204, since the Fe concentration in the sacrificial anode material was high, the self-corrosion rate of the sacrificial anode material after brazing was high, and a through hole was generated in the tube in the corrosion test. In test piece 205, since the Mn concentration in the sacrificial anode material was high, the self-corrosion rate of the sacrificial anode material after brazing was high, and a through hole was generated in the tube in the corrosion test.

[0083] In test piece 206, because the Cu concentration of the core material was high, the core material of the tube was melted during brazing. In test piece 207, because the Mn concentration of the core material was low, the tensile strength after heating equivalent to brazing was less than 70 MPa. In test piece 208, because the Mn concentration of the core material was high, a crack occurred during rolling of the clad material, and a defect-free material was not obtained. In test piece 209, because the Si concentration of the core material was high, the core material of the tube was melted during brazing. In test piece 210, because the Fe concentration of the core material was high, the self-corrosion rate of the core material increased, and a through hole was generated in the tube in the corrosion test.

[0084] In test piece 211, since the Cu concentration of the inner cladding material was lower than the Cu concentration of the core material, the core material did not function as the sacrificial anode layer of the inner cladding material (the inner cladding material did function as the sacrificial anode layer of the core material), and a through hole was created in the tube in the corrosion test. In test piece 212, since the Cu concentration was high, the inner cladding material was melted during brazing. In test piece 213, since the Mn concentration of the inner cladding material was high, a crack occurred during rolling, so a defect-free material was not obtained. In test piece 214, since the Si concentration of the inner cladding material was high, the inner cladding material was melted during brazing.In test piece 215, since the Fe concentration of the inner plating material was high, the self-corrosion rate of the inner plating material increased, and a through hole was generated in the pipe in the corrosion test.

[0085] In test piece 216, because the plating ratio of the sacrificial anode material was low and the pitting potential of the sacrificial anode material surface after brazing exceeded -800 (mV vs. Ag / AgCl), a through hole was generated in the tube during the corrosion test. In test piece 217, because the pitting potential of the sacrificial anode material surface after brazing was less noble than the pitting potential of the aluminum fin, a hole was generated in the tube during the corrosion test. In test piece 218, because the pitting potential of the sacrificial anode material surface after brazing exceeded -800 mV and was less noble than the pitting potential of the aluminum fin, a through hole was generated in the tube during the corrosion test.In test piece 219, since the pitting potential of the sacrificial anode material surface after brazing exceeded -800 mV and was less noble than the pitting potential of the aluminum fin, a through hole was generated in the tube during the corrosion test. In test piece 220, since the pitting potential of the sacrificial anode material surface after brazing was less noble than the pitting potential of the aluminum fin, a through hole was generated in the tube during the corrosion test. [Table 3-1] Nr. Pipe material Rib material Aluminum fin pitting potential - sacrificial anode material surface pitting potential (mV) Tensile strength (MPa) Sacrificial anode material surface pitting potential Aluminum fin pitting potential - sacrificial anode material surface pitting potential Condition after 2500 h corrosion test Success in producing a test piece Sacrificial anode material surface pitting potential (mV vs. Ag / AgCl) Core material pitting potential Pitting corrosion potential of inner cladding material Pitting corrosion potential rib (mV vs. Ag / AgCl) 1 -820 -670 - -900 -80 O O O O O 2 -960 -670 - -1,000 -40 O O O OO O 3 -920 -670 - -960 -40 O O O OO O 4 -930 -670 - -970 -40 O O O OO O 5 -850 -670 - -890 -40 O O O OO O 6 -940 -670 - -980 -40 O O O OO O 7 -950 -670 - -990 -40 O O O OO O 8 -980 -670 - -1,020 -40 O O O OO O 9 -930 -670 - -970 -40 O O O OO O 10 -940 -670 - -980 -40 O O O OO O 11 -880 -670 - -920 -40 O O O OO O 12 -940 -670 - -980 -40 O O O OO O 13 -850 -670 - -890 -40 O O O O O 14 -880 -670 - -920 -40 O O O OO O 15 -940 -680 - -980 -40 O O O OO O 16 -920 -630 - -960 -40 O O O OO O 17 -940 -690 - -980 -40 O O O OO O 18 -940 -660 - -980 -40 O O O OO O 19 -940 -660 - -980 -40 O O O OO O 20 -940 -660 - -980 -40 O O O OO O 21 -940 -660 - -980 -40 O O O OO O 22 -940 -660 - -980 -40 O O O OO O 23 -940 -660 - -980 -40 O O O OO O 24 -940 -660 - -980 -40 O O O OO O 25 -940 -670 - -980 -40 O O O OO O 26 -940 -660 -660 -980 -40 O O O OO O 27 -940 -650 -620 -980 -40 O O O OO O 28 -940 -660 -640 -980 -40 O O O OO O 29 -940 -660 -630 -980 -40 O O O OO O 30 -940 -660 -630 -980 -40 O O O OO O [Table 3-2] Nr . Pipe material Rib material Aluminum fin pitting potential - sacrificial anode material surface pitting potential (mV) Tensile strength (MPa) Sacrificial anode material surface pitting potential Aluminum fin pitting potential - sacrificial anode material surface pitting potential Condition after 2500 h corrosion test Success in producing a test piece Sacrificial anode material surface pitting potential (mV vs. Ag / AgCl) Core material pitting potential Pitting corrosion potential of inner cladding material Pitting corrosion potential rib (mV vs. Ag / AgCl) 31 -940 -660 -630 -980 -40 O O O OO O 32 -940 -660 -630 -980 -40 O O O OO O 33 -940 -660 -630 -980 -40 O O O OO O 34 -940 -660 -630 -980 -40 O O O OO O 35 -940 -660 -630 -980 -40 O O O OO O 36 -940 -660 -630 -980 -40 O O O OO O 37 -940 -660 -630 -980 -40 O O O OO O 38 -940 -660 -630 -980 -40 O O O OO O 39 -940 -660 -630 -980 -40 O O O OO O 40 -940 -660 -630 -980 -40 O O O OO O 41 -940 -650 -630 -980 -40 O O O OO O 42 -940 -645 -630 -980 -40 O O O OO O 43 -940 -660 -630 -980 -40 O O O OO O 44 -940 -660 -630 -980 -40 O O O OO O 45 -940 -660 -630 -980 -40 O O O OO O 46 -940 -645 -640 -980 -40 O O O OO O 47 -940 -645 -640 -980 -40 O O O OO O 48 -940 -645 -635 -980 -40 O O O OO O 49 -940 -645 -635 -980 -40 O O O OO O 50 -940 -660 -630 -945 -5 O O O OO O 51 -940 -660 -630 -950 -10 O O O OO O 52 -940 -660 -630 -955 -15 O O O OO O 53 -940 -660 -630 -970 -30 O O O OO O 54 -940 -660 -630 -990 -50 O O O OO O 55 -940 -660 -630 -1,000 -60 O O O OO O 56 -940 -660 -630 -1,020 -80 O O O OO O 57 -940 -660 -630 -1,030 -90 O O O OO O 58 -940 -660 -630 -1,040 -100 O O O OO O 59 -940 -660 -630 -1,050 -110 O O O OO O 60 -940 -660 -630 -1,060 -120 O O O OO O [Table 3-3] Nr . Pipe material Rib material Aluminum fin pitting potential - sacrificial anode material surface pitting potential (mV) Tensile strength (MPa) Sacrificial anode material surface pitting potential Aluminum fin pitting potential - sacrificial anode material surface pitting potential Condition after 2500 h corrosion test Success in producing a test piece Sacrificial anode material surface pitting potential (mV vs. Ag / AgCl) Core material pitting potential Pitting corrosion potential of inner cladding material Pitting corrosion potential rib (mV vs. Ag / AgCl) 61 -940 -680 - -980 -40 O O O OO O 62 -940 -650 - -980 -40 O O O OO O 63 -930 -645 - -950 -20 O O O OO O 64 -920 -635 - -940 -20 O O O OO O 65 -920 -630 - -940 -20 O O O OO O 66 -940 -680 -660 -980 -40 O O O OO O 67 -940 -680 -650 -980 -40 O O O OO O 68 -940 -670 -645 -980 -40 O O O OO O 69 -940 -660 -630 -980 -40 O O O OO O 70 -940 -650 -625 -980 -40 O O O OO O 71 -940 -650 -625 -980 -40 O O O OO O 72 -940 -660 -660 -980 -40 O O O OO O 73 -940 -660 -650 -980 -40 O O O OO O 74 -930 -645 -645 -970 -40 O O O OO O 75 -940 -650 -620 -980 -40 O O O OO O 76 -940 -650 -620 -980 -40 O O O OO O 77 -930 -635 -620 -980 -50 O O O OO O 78 -850 -660 -630 -900 -50 O O O OO O 79 -950 -660 -630 -1,000 -50 O O O OO O 80 -890 -660 -630 -980 -90 O O O OO O 81 -940 -660 -640 -980 -40 O O O OO O 82 -940 -660 -630 -980 -40 O O O OO O 83 -940 -660 -635 -980 -40 O O O OO O 84 -830 -660 -630 -940 -110 O O O O O 85 -830 -660 -630 -940 -110 O O O O O 86 -840 -660 -630 -940 -100 O O O O O [Table 3-4] Nr. Pipe material Rib material Aluminum fin pitting potential - sacrificial anode material surface pitting potential (mV) Tensile strength (MPa) Sacrificial anode material surface pitting potential Aluminum fin pitting potential - sacrificial anode material surface pitting potential Condition after 2500 h corrosion test Success in producing a test piece Sacrificial anode material surface pitting potential (mV vs. Ag / AgCl) Core material pitting potential Pitting corrosion potential of inner cladding material Pitting corrosion potential rib (mV vs. Ag / AgCl) 87 -840 -660 -630 -940 -100 O O O O O 88 -850 -660 -630 -940 -90 O O O O O 89 -860 -660 -630 -940 -80 O O O O O 90 -870 -660 -630 -940 -70 O O O O O 91 -870 -660 -630 -940 -70 O O O O O 92 -890 -660 -630 -940 -50 O O O OO O 93 -900 -660 -630 -940 -40 O O O OO O 94 -920 -660 -630 -940 -20 O O O OO O 95 -940 -645 - -1,000 -60 O O O OO O 96 -940 -660 -630 -1,000 -60 O O O OO O 97 -940 -645 - -1,000 -60 O O O OO O 98 -950 -660 -630 -1,000 -50 O O O OO O 99 -950 -645 - -1,000 -50 O O O OO O 100 -950 -660 -630 -1,000 -50 O O O OO O 101 -950 -660 -630 -1,000 -50 O O O OO O 102 -950 -645 - -1,000 -50 O O O OO O 103 -960 -660 -630 -1,000 -40 O O O OO O 104 -960 -645 - -1,000 -40 O O O OO O 105 -960 -660 -630 -1,000 -40 O O O OO O 106 -960 -645 - -1,000 -40 O O O OO O 107 -960 -660 -630 -1,000 -40 O O O OO O 108 -960 -645 - -1,000 -40 O O O OO O 109 -960 -660 -630 -1,000 -40 O O O OO O [Table 4] Nr. Pipe material Rib material Aluminum fin pitting potential - sacrificial anode material surface pitting potential (mV) Tensile strength (MPa) Sacrificial anode material surface pitting potential Aluminum fin pitting potential - sacrificial anode material surface pitting potential Condition after 2500 h corrosion test Success in producing a test piece Sacrificial anode material surface pitting potential (mV vs. Ag / AgCl) Core material pitting potential Pitting corrosion potential of inner cladding material Pitting corrosion potential rib (mV vs. Ag / AgCl) 201 -770 -660 - -810 -40 O × O × O 202 -960 -660 - -940 20 O O × × O 203 -920 -660 - -960 -40 O O O × O 204 -930 -660 - -970 -40 O O O × O 205 -840 -660 - -880 -40 O O O × O 206 - - - - - - - - - × 207 -940 -710 - -980 -40 × O O O O 208 - - - - - - - - - × 209 - - - - - - - - - × 210 -940 -660 - -980 -40 O O O × O 211 -940 -645 -660 -980 -40 O O O × O 212 - - - - - - - - - × 213 - - - - - - - - - × 214 - - - - - - - - - × 215 -940 -660 -630 -980 -40 O O O × O 216 -790 -660 -630 -830 -40 O × O × O 217 -850 -660 -630 -700 150 O O × × O 218 -750 -660 -630 -700 50 O × × × O 219 -780 -660 -630 -700 80 O × × × O 220 -820 -660 -630 -750 70 O O × × O

Claims

[1] An aluminum alloy heat exchanger having an atmosphere side used in a dilute chloride ion environment of 1000 ppm or less, the aluminum alloy heat exchanger being formed by brazing a tube and an aluminum fin, the tube being formed of a two-layer aluminum alloy clad tube material of an aluminum alloy core material and a sacrificial anode material clad on a side surface of the core material such that the core material serves as a coolant passage side and the sacrificial anode material serves as the atmosphere side, wherein the core material is formed of an aluminum alloy containing 0.60 to 2.00 mass% of Mn and 1.00 mass% or less of Cu, and optionally further comprising 1.50 mass% or less of Si and / or 0.70 mass% or less of Fe and / or 0.01 to 0.30 mass% of Ti, the remainder being Al and unavoidable impurities, the sacrificial anode material is formed of an aluminum alloy containing 2.50 to 10.00 mass% of Zn and optionally further comprising at least one of 1.50 mass% or less of Si, 1.50 mass% or less of Fe, and 1.50 mass% or less of Mn, the remainder being Al and unavoidable impurities, a pitting corrosion potential of a sacrificial anode material surface of the tube of the aluminum alloy heat exchanger in a 5% NaCl solution is -800 (mV vs. Ag / AgCl) or less and a pitting potential of the aluminum fin of the aluminum alloy heat exchanger in a 5% NaCl solution is smaller than the pitting potential of the sacrificial anode material surface of the tube of the aluminum alloy heat exchanger in a 5% NaCl solution. [2] An aluminum alloy heat exchanger having an atmosphere side used in a dilute chloride ion environment of 1000 ppm or less, the aluminum alloy heat exchanger being formed by brazing a tube and an aluminum fin, the tube being formed of a three-layer aluminum alloy clad tube material made of an aluminum alloy core material, a sacrificial anode material clad on one side surface of the core material, and an inner clad material clad on the other side surface of the core material such that the inner clad material serves as a coolant passage side and the sacrificial anode material serves as the atmosphere side, wherein the core material is formed of an aluminum alloy containing 0.60 to 2.00 mass% of Mn and 0.60 mass% or less of Cu, and optionally further comprising 1.50 mass% or less of Si and / or 0.70 mass% or less of Fe and / or 0.01 to 0.30 mass% of Ti, the remainder being Al and unavoidable impurities, the sacrificial anode material is formed of an aluminum alloy containing 2.50 to 10.00 mass% of Zn and optionally further comprising one or more of 1.50 mass% or less of Si, 1.50 mass% or less of Fe, and 1.50 mass% or less of Mn, the remainder being Al and unavoidable impurities, the inner plating material is formed of an aluminum alloy containing 0.60 to 2.00 mass% of Mn and 0.20 to 1.50 mass% of Cu, and optionally further comprising 1.50 mass% or less of Si and / or 0.70 mass% or less of Fe and / or 0.01 to 0.30 mass% of Ti, the remainder being Al and unavoidable impurities, a difference (YX) between a Cu content (Y) of the inner cladding material of the three-layer aluminum alloy cladding tube material and a Cu content (X) of the core material of the three-layer aluminum alloy cladding tube material is greater than 0.00 mass%, a pitting corrosion potential of a sacrificial anode material surface of the tube of the aluminum alloy heat exchanger in a 5% NaCl solution is -800 (mV vs. Ag / AgCl) or less and a pitting potential of the aluminum fin of the aluminum alloy heat exchanger in a 5% NaCl solution is smaller than the pitting potential of the sacrificial anode material surface of the tube of the aluminum alloy heat exchanger in a 5% NaCl solution.

Images