JP2014062296A - Aluminum alloy brazing sheet excellent in corrosion resistance - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an aluminum alloy brazing sheet excellent in corrosion resistance, in which corrosion resistance of an exterior surface (a surface in an open air side) and a junction of a header plate material and a tube material are improved when the header plate material is used for example, as well as excellent in brazability by using a brazing material without adding Zn.SOLUTION: An aluminum alloy brazing sheet excellent in corrosion resistance is obtained by cladding a first brazing material on one side of a surface of a core material, the core material is an aluminum alloy containing, by mass%, Si: 0.02 to 0.3%, Fe: 0.02 to 0.3%, Cu: 0.3 to 1.0%, Mn: 0.6 to 1.8, Zn: 0.2 to 1.5%, Ti: 0.05 to 0.25%, and the balance Al with inevitable impurities, the first brazing material is an aluminum alloy containing Si: 3.0 to 6.7%, Fe: 0.1 to 1.5% and the balance Al with inevitable impurities.

Description

  The present invention relates to a brazing sheet which is used mainly as a header plate constituting a medium flow path of a heat exchanger for automobiles such as a condenser and an evaporator, and has particularly excellent brazing property and corrosion resistance.

Aluminum alloy header plate materials used in conventional automotive heat exchangers include, for example, JIS3003 alloy as the core material, and a skin made of Al-Si-Zn alloy or Al-Zn alloy on the outer surface of the heat exchanger. A brazing sheet formed by cladding a material is used. In the manufacture of aluminum alloy automotive heat exchangers such as radiators, heaters, condensers, and evaporators, in general, aluminum plates and extrusions molded into a predetermined shape are assembled into a predetermined structure, and then a fluoride-based heat exchanger is assembled. A method of applying flux and brazing and joining in a heating furnace in an inert gas atmosphere is employed.
In recent years, in heat exchangers for automobiles, the thickness of constituent materials has been reduced from the viewpoints of energy saving and resource saving, and header plates of constituent members have also become thinner. Therefore, corrosion resistance has been improved by adding Zn to the brazing material. However, when trying to ensure corrosion resistance by adding Zn to the brazing material, Zn concentrates in the eutectic structure at the joint between the header plate material and the tube material. The problem was that preferential corrosion became prominent and lead to early penetration.
Patent Document 1 discloses a method for improving the corrosion resistance without adding Zn to the brazing material. In this document, a header formed by clad an aluminum alloy brazing material containing Si: 1.6 to 5.0% and Mn: 0.05 to 1.6% on the surface of the aluminum alloy core material on the refrigerant side Aluminum alloy materials for plates have been proposed. In Patent Document 1, it is described that a brazing material not containing Zn is used and exhibits good corrosion resistance in an alkaline environment on the refrigerant side. However, in the joint portion between the outer surface and the header plate material or the tube material. There is no mention of corrosion resistance.

JP 2008-303405 A

The present invention uses a brazing material to which no Zn is added, and is excellent in brazing properties. For example, in the outer surface when used as a header plate material (surface on the outside air side) and the joint portion between the header plate material and the tube material. An object of the present invention is to provide an aluminum alloy brazing sheet with improved corrosion resistance and excellent corrosion resistance.
Another object of the present invention is to provide a heat exchanger using the brazing sheet and improving the corrosion resistance at the outer surface of the header plate material and the joint portion between the header plate material and the tube material.

In order to solve the problems as described above, the present inventors have made various studies, and as a result, achieve the above object when the core material and brazing material constituting the aluminum alloy brazing sheet have a specific component composition. And the present invention has been made based on this finding.
That is, the said subject was solved by the following invention.
[1] An aluminum alloy brazing sheet in which one main surface of a core material is clad with a first brazing material,
The core material is Si: 0.02 to 0.3% (mass%, the same applies hereinafter), Fe: 0.02 to 0.3%, Cu: 0.3 to 1.0%, Mn: 0.6 -1.8, Zn: 0.2-1.5%, Ti: 0.05-0.25%, the balance is an aluminum alloy consisting of Al and inevitable impurities,
The first brazing material contains Si: 3.0 to 6.7%, Fe: 0.1 to 1.5%, and the balance is an aluminum alloy composed of Al and inevitable impurities. Aluminum alloy brazing sheet with excellent corrosion resistance.
[2] The aluminum alloy brazing sheet excellent in corrosion resistance according to [1], wherein the second main surface of the core material is clad with a second brazing material made of an Al—Si alloy.
[3] The second brazing material made of the Al—Si alloy contains Si: 6.2 to 12.0%, Fe: 0.1 to 0.5%, Cu: 0.2 to 1.5%. The aluminum alloy brazing sheet having excellent corrosion resistance according to [2], wherein the aluminum alloy is an aluminum alloy containing Al and inevitable impurities.
[4] The total thickness of the aluminum alloy brazing sheet is t (μm), the thickness of the first brazing material is a (μm), and the amount of Si in the first brazing material is b (%). If you want to
50 <a ≦ −20 × b + 285 (1)
0.03 × t ≦ a ≦ 0.30 × t (2)
The aluminum alloy brazing sheet having excellent corrosion resistance according to any one of [1] to [3], wherein the following relationship is satisfied.
[5] For automobiles comprising a plurality of tanks, a plurality of tubes installed between the tanks, a fin member brazed to each tube, and a header plate member sandwiching the plurality of tubes. In the heat exchanger, the aluminum alloy brazing sheet according to any one of [1] to [4] is used as the header plate material.

  According to the present invention, the brazing material to which Zn is not added is used, and the brazing property is excellent. For example, the outer surface when used as the header plate material and the corrosion resistance at the joint portion between the header plate material and the tube material are improved. It is possible to provide an aluminum alloy brazing sheet excellent in the above. Moreover, the heat exchanger which uses the said brazing sheet and can improve the corrosion resistance in the outer surface of a header plate material and the junction part of this header plate material and a tube material can be provided.

It is sectional drawing which shows schematic shape of the test piece for evaluating the corrosion resistance in the junction part of the header plate material and tube material in an Example.

Hereinafter, details of the present invention and other features and advantages will be described based on embodiments.
[1. Core material]
The core material contains Si, Fe, Cu, Mn, Zn, and Ti as essential components, and consists of the balance Al and inevitable impurities. In addition, the content of each element and the effects based on it are as described below.
Si:
Si forms an Al-Mn-Si-based or Al-Fe-Mn-Si-based intermetallic compound together with Mn and Fe, and acts on coarsening of grains after brazing, or is dissolved in an aluminum matrix. Thus, there is an effect of improving the strength by solid solution strengthening. The Si content is in the range of 0.02 to 0.3%. If the amount is too small, the effect is insufficient. If the amount is too large, the types of intermetallic compounds produced increase, the cathode sites increase, and the corrosion resistance of the core material decreases. Preferably, it is 0.05 to 0.2%.
Fe:
Fe forms an Al—Fe—Mn—Si-based or Al—Fe—Si-based intermetallic compound together with Mn and Si, and acts on coarsening of crystal grains after brazing. The content of Fe is 0.02 to 0.3%. If the amount is too large, the types of intermetallic compounds produced increase, the cathode sites increase, and the corrosion resistance of the core material decreases. If the amount is too small, high-purity aluminum ingots must be used, resulting in high costs. Preferably, it is 0.05 to 0.2%. However, when the cost is not considered, the smaller the Fe content, the better.

Cu:
Cu has an effect of improving strength by solid solution strengthening and promoting age hardening. Since the Cu content can further increase the potential, it can contribute to the improvement of corrosion resistance. The Cu content is in the range of 0.3 to 1.0%. If the amount is too small, the effect is insufficient. If the amount is too large, the intergranular corrosion sensitivity increases, and conversely, the corrosion resistance decreases. Preferably, it is 0.35 to 0.6%.
Mn:
Mn forms an Al-Mn-Si-based or Al-Fe-Mn-Si-based intermetallic compound together with Si and Fe and acts on the coarsening of crystal grains after brazing, or forms a solid solution in the aluminum matrix. And strength is improved by solid solution strengthening. In addition, it forms a dense compound with Si that diffuses from the brazing material during the heat of brazing, contributing to improved corrosion resistance. The Mn content is 0.6 to 1.8%. If the amount is too small, the effect is insufficient. If the amount is too large, the use of Mn increases, and a coarse intermetallic compound is produced, resulting in a decrease in workability and corrosion resistance. Preferably, it is 0.8 to 1.5%.

Zn:
Zn has the effect of lowering the electric potential, and when it is appropriately contained, corrosion weight loss can also be reduced. The Zn content is adjusted as necessary according to the relative relationship of the potential of the tube material, core material, and joint. However, if the amount is too small, the above action cannot be obtained sufficiently, while if it is excessively contained, the self-corrosion rate is increased. For this reason, it is desirable that the Zn content is 0.2 to 1.5%.
Ti:
Ti improves the strength by solid solution strengthening. Moreover, there exists an effect which suppresses that Ti precipitates in a layer form in a core material and a pitting corrosion advances to a depth direction. The Ti content is 0.05 to 0.25%. If the amount is too small, the effect cannot be obtained. If the amount is too large, a coarse intermetallic compound is likely to be formed, and the workability and corrosion resistance deteriorate. More preferably, it is 0.08 to 0.2%.
Other:
In addition to the above elements in the core material, the effects of the present invention are not impaired even if 0.3% or less of Zr, V, or the like is contained. The balance may be Al and inevitable impurities. The contents of inevitable impurities are each 0.05% or less, and the total amount is preferably 0.15% or less.

[2. First brazing material]
For example, when the aluminum alloy brazing sheet is used as a header plate material of a heat exchanger, the main surface of the core material clad with the first brazing material is positioned outward.
The first brazing material clad on one main surface of the core material described above mainly contains Si and Fe, and consists of the balance Al and inevitable impurities. Further, the content of each element and the effects based on it are as described below.
Si:
Si is an essential element for functioning as a brazing material in a liquid phase during brazing addition heat. For example, it is an element that enables brazing when brazing the aluminum alloy brazing sheet of the present invention to a tube material. Most of the brazing layer is in the α phase, and a small amount of the eutectic part flows out to the surface and functions as a brazing material. The corrosion resistance of the α phase remaining after the brazing heat is very good, and the brazing layer can have high corrosion resistance. The Si content is 3.0 to 6.7%. If the amount of Si is too small, the resulting liquid phase becomes small and external brazing becomes difficult to function. On the other hand, when the amount of Si is too large, most of it flows as a liquid phase at the time of brazing addition heat and hardly remains on the surface, making it difficult to form the brazing layer itself and failing to function as an anticorrosion layer. A preferable amount of Si is 3.0 to 5.5%.
Fe:
Fe forms, for example, an Al-Fe-based or Al-Fe-Si-based compound in the eutectic portion in the joint when the aluminum alloy brazing sheet of the present invention is overlapped with a tube material to form a heat exchanger or the like. . Since these compounds serve as starting points of corrosion, the corrosion resistance is improved by the sacrificial anode effect. On the other hand, in the eutectic part in the joint, these compounds serve as a cathode and promote the occurrence of preferential corrosion. Therefore, the Fe content is set to 0.1 to 1.5% by considering the trade-off relationship between these functions and effects. If the amount of Fe is too small, the Al—Fe—Si-based compound present in the surface layer decreases and the corrosion resistance decreases, and if the amount of Fe is too large, the Al—Fe-based or Al—Fe— Since the number of Si-based compounds increases, the corrosion resistance of the joint portion decreases. In order to secure these effects more reliably, the Fe content is preferably 0.2 to 1.0%.

[3. (1) and (2)]
The aluminum alloy brazing sheet of the present invention is excellent in brazeability and, for example, in order to improve the corrosion resistance at the outer surface when used as a header plate material and the joint between the header plate material and the tube material, The first brazing material satisfies the above-described requirements, the total thickness of the aluminum alloy brazing sheet is t (μm), the thickness of the brazing material is a (μm), and the amount of Si in the brazing material is b. In the case of (%), it is preferable that the following formulas (1) and (2) are satisfied.
50 <a ≦ −20 × b + 285 (1)
0.03 × t ≦ a ≦ 0.30 × t (2)
The formula (1) particularly secures the above corrosion resistance, and the formula (2) can sufficiently control the cladding rate when the brazing layer is formed on the main surface of the core material by the brazing addition heat. It is a condition to make it. As a result of intensive studies, it is preferable for the formula (1) that the brazing material thickness is 50 μm or more in order to ensure the corrosion resistance, and considering the brazing property, the brazing material thickness is (−20 × b + 285). It has been found that it is preferable to suppress it to μm or less. If it is less than the lower limit, the corrosion resistance is lowered. Further, in consideration of manufacturability, it is preferable to set the cladding rate to 3 to 30% as shown in the equation (2). If it deviates from the range of the formula (2), the production yield will be reduced.

  That is, the first brazing filler metal exhibits high corrosion resistance by satisfying the composition component and the relational expression, and therefore, the effect of the first brazing material can be sufficiently exerted particularly when it is positioned outward. It is. Furthermore, preferential corrosion of the eutectic structure at the joint between the header plate material and the tube material can be improved by adding Zn to the core material. However, it is not excluded to place the first brazing material inside the header plate material.

[4. Second brazing material]
For example, when the aluminum alloy brazing sheet is used as a header plate material of a heat exchanger, the other main surface clad with the second brazing material is positioned inward (surface on the refrigerant side). Therefore, since high corrosion resistance is not required unlike the brazing material described above, a commonly used Al—Si alloy can be used as the brazing material. A commonly used Al—Si based alloy is, for example, an alloy containing 6.2 to 12.0% Si and 0.1 to 0.5% Fe, with the balance being Al and inevitable impurities.
Moreover, it is preferable to add Cu to the second brazing material because it exhibits an effect of improving the corrosion resistance at the joint between the header plate material and the tube material. The reasons for limiting Cu added only to the second brazing filler metal on the refrigerant passage side are as follows.
Cu:
Cu in the second brazing material contributes to an improvement in the corrosion resistance of the joint between the header plate material and the tube material. By adding Cu into the second brazing material in consideration of the balance with the core material, the corrosion resistance of the joint can be improved. Moreover, it becomes a supply source for forming a Cu concentration gradient from the brazing material on the refrigerant passage side to the brazing material on the air side after the brazing heat, and the life until corrosion penetrates can be improved. If Cu exceeding 0.2% is added, a sufficient potential difference between the core material and the brazing material surface can be secured, which contributes to an improvement in corrosion resistance. On the other hand, if Cu is added more than necessary, the joint portion becomes too noble in terms of potential, and the core material will preferentially corrode and become more susceptible to cracking during casting, resulting in very poor productivity. Become. In order to avoid such a phenomenon, the amount of Cu needs to be 1.5% or less. Moreover, it is more preferable to make it less than 0.7%.

[5. Manufacturing method of aluminum alloy brazing sheet]
The aluminum alloy brazing sheet described above can be produced, for example, as follows.
As the core material, the above-described aluminum alloys having the desired component composition are respectively melted and cast. In order to make the intermetallic compound produced during casting fine, the cooling rate during casting is preferably 0.5 ° C./s or more. It is preferable that the ingot is finished by chamfering, and before the hot rolling, the ingot is not homogenized or at 550 ° C. or higher. By not homogenizing the core material, the intermetallic compound obtained at the time of casting can be subjected to subsequent steps while maintaining a fine state. Alternatively, the homogenization treatment of the core material is performed at 550 ° C. or higher, so that the intermetallic compound in the core material can be re-dissolved and finely precipitated again in the subsequent steps.
The obtained core material is combined with the first brazing material having the desired composition as described above or, if necessary, the second brazing material, heated in that state, and subjected to hot clad rolling. Here, this hot clad rolling is hereinafter simply referred to as “hot rolling”. The thickness of the laminated material before hot rolling is not particularly limited, but is usually about 250 to 800 mm (preferably about 300 to 600 mm).
The temperature before hot rolling of this combination material is, for example, 450 ° C. or more and 550 ° C. or less and 2 hours or more and 20 hours or less, and the temperature when the plate thickness reaches 20 mm, for example, during the hot rolling process is 400 ° C. or more. The clad material is produced by controlling and controlling the temperature at the end of hot rolling to 300 ° C. or higher. By such control, precipitation of fine intermetallic compounds occurs during heating before hot rolling, during hot rolling, and after hot rolling, and an appropriate distribution of intermetallic compounds is obtained.
The clad material obtained by hot rolling is then rolled to a predetermined plate thickness by cold rolling. During the cold rolling or after the cold rolling, an annealing process may be performed about once or twice. The annealing step is usually performed at 200 to 500 ° C. for 1 to 10 hours using a batch furnace, or at 200 to 550 ° C. using a continuous furnace.

Hereinafter, the present invention will be described in more detail based on examples. It should be noted that this embodiment is only for explaining the effect of the present invention, and the technical scope of the present invention is not limited by the embodiment.
(Examples 1-17 and Comparative Examples 1-11)
The core material having the component composition shown in alloy codes a1 to a14 in Table 1, the first brazing material on the outer surface side of the component composition shown in alloy codes b1 to b7 in Table 2, and the components shown in alloy codes c1 to c4 in Table 3 The second brazing material on the inner surface side of the composition was DC casted to produce an ingot.
The first brazing material on the outer surface side and the second brazing material on the inner surface side were hot-rolled at 500 ° C. to a predetermined plate thickness after chamfering. The core material was chamfered after homogenizing the ingot at 580 ° C. for 6 hours. The first brazing material on the outer surface side, the core material, the second brazing material on the inner surface side are stacked in this order, heated to 480 ° C. and then hot-rolled to form a three-layer clad material with a thickness of 3.5 mm, This was cold-rolled to 2.0 mm, then annealed at 360 ° C. for 3 hours, and then cold-rolled to a predetermined plate thickness to obtain an evaluation clad material.
By press molding, the three-layer clad material is pressed into a header plate shape, combined with tube material, fin material and reinforcing material, applied with Nocolok flux, dried, and then brazed at 600 ° C for 3 minutes in a high-purity nitrogen gas atmosphere The heat treatment was performed to produce a heat exchanger (size: tube width 16 mm, core size: 160 mm length × 200 mm width) having 16 stages of tubes. In addition, each component composition value shown to Table 1-Table 3 was measured with the emission-spectral-analysis apparatus.

  Table 4 shows the combination of the core material and the brazing material, the final plate thickness, and the evaluation results for each of the obtained clad materials.

An evaluation method of manufacturability, tensile strength, brazing property, and corrosion resistance will be described.
Manufacturability evaluation:
When the clad material was manufactured, a case where a sound clad material was produced was marked with ◯, and when a crack occurred during casting or when the clad rate could not be controlled, x was marked.
Tensile strength measurement:
A JIS No. 5 test piece was cut out from each aluminum alloy clad material, heated at 600 ° C. for 3 minutes in a nitrogen atmosphere as a brazing equivalent heat treatment, a tensile test was conducted, and the tensile strength was examined. And the tensile strength after brazing equivalent heat processing made 120 MPa or more (circle) and 120 MPa or less x.
Brazing evaluation:
Five heat exchangers made of the respective clad materials were submerged, sealed with nitrogen gas at a pressure of 180 KPa inside the heat exchanger, sealed, and held for 30 seconds. The core without leakage did not have a pressure drop, and the core where the pressure drop occurred confirmed the location where bubbles were generated in a submergence test. Of the five units examined, the case where there was no leakage from the fitting portion between the tube material and the header plate material was marked with ◯. The results are shown in Table 4.
Corrosion resistance evaluation:
A sample was cut out from the produced heat exchanger, and a test material for corrosion test was prepared in which the opening of the cut portion was covered with resin so that no corrosive liquid entered the hollow body. For the corrosion resistance evaluation, the SWAAT test (based on ASTM G85) was performed for 1000 hours.
(1) Header plate material flat portion The maximum corrosion depth after the SWAAT test of the header plate flat portion was measured, and the results are shown in Table 4 based on the following criteria.
Evaluation criteria: A pass (◯) was given if the corrosion remained in the brazing filler metal layer on the outer surface side, and a failure (x) was given if the corrosion reached the core material.
(2) Joint portion of header plate material and tube material The corrosion state of the joint portion of the header plate and the tube after the SWAAT test was investigated and shown in Table 4 according to the following criteria.
Evaluation criteria: Preferential corrosion length of the corroded portion C at the joint portion 31 between the header plate material 21 and the tube material 22 shown in FIG. 1 (the length at which the joint portion 31 corroded preferentially over the header plate material 21 and the tube material 22). ) L is less than 0.3 mm, and X is 0.3 mm or more.
As shown in Table 4, as a result of various tests, in Examples 1 to 17 of the present invention, all of the productivity, tensile strength, brazing property, and corrosion resistance were applied to the use and environment to which the clad material of the present invention was applied. It was confirmed that it was suitable. Moreover, in Comparative Examples 1-11, it turned out that it becomes an unreasonable result in the use and environment where the clad material of this invention is used, as described below.
In the case of Comparative Example 1, sufficient tensile strength could not be obtained because the amount of Mn in the core material was small. On the other hand, in the case of Comparative Example 2, since the amount of Mn in the core material is large, a coarse intermetallic compound is generated and the corrosion resistance is lowered.
In the case of Comparative Example 3, since the amount of Si in the core material is large, the types of intermetallic compounds produced such as Al—Mn—Si or Al—Fe—Mn—Si are increased, and the cathode sites are increased. As a result, the corrosion resistance of the core material decreased. In the case of Comparative Example 4, since the amount of Fe in the core material is large, the types of intermetallic compounds produced such as Al—Mn—Si or Al—Fe—Mn—Si are increased, and the cathode sites are increased. As a result, the corrosion resistance of the core material decreased.
In the case of Comparative Example 5, since the amount of Cu in the core material is small, the sacrificial anode effect of the first brazing material on the outer surface side is insufficient, and the corrosion resistance is lowered. In Comparative Example 6, intergranular corrosion occurred because the amount of Cu in the core material was large.
In the case of Comparative Example 7, since the amount of Ti in the core material was small, Ti precipitation was not sufficient and the corrosion resistance was lowered. In the case of Comparative Example 8, since the amount of Ti in the core material was large, a coarse intermetallic compound was generated and could not be rolled.
In the case of the comparative example 9, since there was much Zn amount in a core material, self-corrosion resistance deteriorated and the corrosion resistance of the flat part fell.
In the case of Comparative Example 10, since the amount of Si and Fe in the first brazing filler metal on the outer surface side was small, brazing joining was insufficient, so that the corrosion resistance of the joint could not be evaluated. In the case of Comparative Example 11, since the amount of Si in the first brazing filler metal on the outer surface side is large, it flows almost as a liquid phase at the time of brazing addition heat, and cannot function as an anticorrosion layer, and the amount of Fe is also large. Therefore, the compound of the eutectic part in the joint portion increased, the compound worked as a cathode, and corrosion around the compound became remarkable.

(Examples 18 to 32 and Comparative Examples 12 to 22)
The core material having the component composition indicated by alloy codes a1 to a14 in Table 1 and the first brazing material on the outer surface side having the component composition indicated by alloy codes b1 to b7 in Table 2 were each DC casted to produce ingots.
The first brazing material on the outer surface side was hot-rolled at 500 ° C. after chamfering to a predetermined plate thickness. The core material was chamfered after homogenizing the ingot at 580 ° C. for 6 hours. The first brazing material and the core material on the outer surface side are stacked in this order, heated to 480 ° C., and then hot-rolled to form a two-layer clad material having a thickness of 3.5 mm, which is cold-rolled to 2.0 mm Then, after annealing at 360 ° C. for 3 hours, cold rolling was performed to a predetermined plate thickness to obtain a clad material for evaluation.
By press molding, the two-layer clad material is pressed into a header plate shape, combined with tube material, fin material and reinforcing material, applied with Nocolok flux, dried, and then brazed at 600 ° C for 3 minutes in a high-purity nitrogen gas atmosphere The heat treatment was performed to produce a heat exchanger (size: tube width 16 mm, core size: 160 mm length × 200 mm width) having 16 stages of tubes. Table 5 shows the combination of the core material and the brazing material, the final plate thickness, and the evaluation results for each of the obtained clad materials. The evaluation of manufacturability, tensile strength, brazing property, and corrosion resistance was carried out in the same manner as in Example 1.

As shown in Table 5, as a result of various tests, in Examples 18 to 32 of the present invention, all of the productivity, tensile strength, brazing property, and corrosion resistance were applied to the use and environment to which the clad material of the present invention was applied. It was confirmed that it was suitable. Moreover, in Comparative Examples 12-22, it turned out that it becomes an unreasonable result in the use and environment where the clad material of this invention is used as described below.
In the case of Comparative Example 12, sufficient tensile strength was not obtained because the amount of Mn in the core material was small. In the case of Comparative Example 13, since the amount of Mn in the core material was large, a coarse intermetallic compound was generated and the corrosion resistance was lowered.
In the case of Comparative Example 14, since the amount of Si in the core material is large, the types of intermetallic compounds produced such as Al-Mn-Si or Al-Fe-Mn-Si are increased, and the cathode sites are increased. As a result, the corrosion resistance of the core material decreased. In the case of Comparative Example 15, since the amount of Fe in the core material is large, the types of intermetallic compounds produced such as Al-Mn-Si or Al-Fe-Mn-Si are increased, and the cathode sites are increased. As a result, the corrosion resistance of the core material decreased.
In the case of Comparative Example 16, since the amount of Cu in the core material was small, the sacrificial anode effect of the brazing material on the outer surface side became insufficient and the corrosion resistance was lowered. In the case of the comparative example 17, since the amount of Cu in the core material is large, intergranular corrosion has occurred.
In the case of Comparative Example 18, since the amount of Ti in the core material was small, Ti was not sufficiently precipitated and the corrosion resistance was lowered. In the case of Comparative Example 19, since the amount of Ti in the core material was large, a coarse intermetallic compound was generated and could not be rolled.
In the case of Comparative Example 20, since the amount of Zn in the core material was large, the self-corrosion resistance was deteriorated, and the corrosion resistance of the flat portion was lowered.
In the case of Comparative Example 21, since the amount of Si and the amount of Fe in the brazing material on the outer surface side were small, brazing joining was insufficient, and thus the corrosion resistance of the joint could not be evaluated. In the case of Comparative Example 22, since the amount of Si in the brazing material on the outer surface side is large, it flows almost as a liquid phase at the time of brazing addition heat and cannot function as an anticorrosion layer. The compound of the eutectic part in the part increased, the compound worked as a cathode, and corrosion around the compound became remarkable.

  The present invention has been described in detail based on the above specific examples. However, the present invention is not limited to the above specific examples, and various modifications and changes can be made without departing from the scope of the present invention.

21 Header plate material 22 Tube material 31 Joint C Corrosion part L Preferential corrosion length

Claims (5)

An aluminum alloy brazing sheet in which a first brazing material is clad on one main surface of a core material,
The core material is Si: 0.02 to 0.3% (mass%, the same applies hereinafter), Fe: 0.02 to 0.3%, Cu: 0.3 to 1.0%, Mn: 0.6 -1.8, Zn: 0.2-1.5%, Ti: 0.05-0.25%, the balance is an aluminum alloy consisting of Al and inevitable impurities,
The first brazing material contains Si: 3.0 to 6.7%, Fe: 0.1 to 1.5%, and the balance is an aluminum alloy composed of Al and inevitable impurities. Aluminum alloy brazing sheet with excellent corrosion resistance.   The aluminum alloy brazing sheet excellent in corrosion resistance according to claim 1, wherein the second main surface of the core material is clad with a second brazing material made of an Al-Si alloy.   The second brazing material made of the Al-Si alloy contains Si: 6.2 to 12.0%, Fe: 0.1 to 0.5%, Cu: 0.2 to 1.5%, The aluminum alloy brazing sheet having excellent corrosion resistance according to claim 2, wherein the balance is an aluminum alloy composed of Al and inevitable impurities. When the total thickness of the aluminum alloy brazing sheet is t (μm), the thickness of the first brazing material is a (μm), and the amount of Si in the first brazing material is b (%) ,
50 <a ≦ −20 × b + 285 (1)
0.03 × t ≦ a ≦ 0.30 × t (2)
The aluminum alloy brazing sheet excellent in corrosion resistance according to any one of claims 1 to 3, wherein the following relationship is satisfied.   An automotive heat exchanger comprising a plurality of tanks, a plurality of tubes installed between the tanks, a fin member brazed to each tube, and a header plate member sandwiching the plurality of tubes. The heat exchanger using the aluminum alloy brazing sheet according to any one of claims 1 to 4 as the header plate material.

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