JP2006152325A - Aluminum alloy brazing sheet for heat exchanger and its production method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a brazing sheet composed of a three layer clad plate used at the time when a heat exchanger made of an aluminum alloy is produced by a brazing process, which has excellent strength, bending fatigue properties and corrosion resistance, in which the fluidity of a brazing filler metal is suitable, and which has no generation of defects in brazing and erosion even when brazed using fluoride based flux. <P>SOLUTION: The brazing sheet is composed of an aluminum alloy clad plate with a three layer structure consisting of an aluminum alloy as a core material having a composition comprising, by mass, 0.3 to 1.0% Si, 0.3 to 0.8% Fe, 0.8 to 1.6% Mn and 0.5 to 0.9% Cu, and in which the content of Mg as impurities is regulated to ≤0.05%, and the balance Al with inevitable impurities, an aluminum alloy as a sacrificial anode material having a composition comprising 0.2 to 0.6% Mg and 0.1 to 0.3% Zn, and the balance Al with inevitable impurities, and an aluminum alloy as a brazing filler metal comprising 6.5 to 8.5% Si and 0.15 to 0.6% Fe, and in which the content of Mg as impurities is regulated to ≤0.05%, and the balance Al with inevitable impurities. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention is a high-strength aluminum alloy brazing header plate for heat exchangers excellent in brazing, corrosion resistance, and bending fatigue properties (repetitive pressure resistance), and more specifically, radiators, intercoolers, oil coolers for transport aircraft, The present invention relates to an aluminum alloy brazing header plate material used in a heat exchanger in which a working fluid passage constituting material such as a car heater and a thin fin material are joined by brazing. More specifically, the present invention relates to a high-strength aluminum alloy brazing sheet for heat exchangers that is excellent in brazing properties, corrosion resistance, and bending fatigue properties as a header plate used by molding.

Heat exchangers such as radiators, intercoolers, oil coolers and car heaters for transport aircraft are made of Al-Mn alloy, Al-Mn-Cu alloy, etc. The brazing material and the tube sheet and the header plate clad with the sacrificial anode material made of an Al—Zn alloy are brazed with the fin material and / or the side plate clad with the core material and the brazing material. It is assembled. That is, the heat exchanger made of aluminum is assembled by brazing each member.
During this brazing, a non-corrosive fluoride-based flux is used to remove the oxide film on the aluminum surface to be brazed.

  For the construction of the working fluid passage which is the main element constituting the heat exchanger made of aluminum, an Al—Mn alloy such as 3003 alloy is used as a core material, and a solder material such as 4343 alloy or 4045 alloy is used on one side thereof. A brazing sheet is used in which an Al—Si alloy is clad and an Al—Zn alloy such as 7072 alloy is clad on the other surface as a sacrificial anode material. The brazing sheet is required to have brazing properties and corrosion resistance.

  For example, in Patent Document 1, an Al alloy brazing material containing Si: 3 to 15 wt% in an Al alloy core material containing Mn: 0.5 to 1.5 wt%, and Mn: 0.05 to 0 .5 wt%, Mg: 0.05 to 0.5 wt% of one or two types and Zn: 0.05 to 0.5 wt% Al alloy sacrificial anode material clad with a three-layer structure Al alloy composite pipes for heat exchangers having excellent pitting corrosion resistance and mechanical strength have been proposed.

  Further, in Patent Document 2, a core material of Al alloy containing Mn: 0.7 to 1.5% by weight and an electrochemical base compared to the core material, Zn: 0.1 to 0 0.5% by weight, Mg: 0.1 to 0.5% by weight, Fe as impurity elements: 0.25% by weight or less, Si: 0.15% by weight or less, Cu: 0.05% by weight or less A radiator tank material excellent in crevice corrosion resistance composed of an Al alloy clad plate made of an Al alloy skin material has been proposed.

Further, in Patent Document 3, Si: 0.05 to 0.8 wt%, Fe: 0.05 to 0.6 wt%, Mn: 0.4 to 1.6 wt%, Mg: 0.05 to 0 Al alloy containing 0.5% by weight, further containing Cr: 0.3% by weight or less, Zr: 0.3% by weight or less, Ti: 0.3% by weight or less An Al alloy having an Al-Si alloy brazing material on one side and a sacrificial effect on the other side, and having a Mg content of 0.05 wt% or more and not more than the Mg content of the core material. A high-strength, high-corrosion-resistant aluminum brazing sheet having an Al alloy contained in has been proposed.
JP-A-60-141844 Japanese Patent No. 2608890 JP-A-5-43971

  Recently, however, there is an increasing demand for weight reduction and cost reduction of heat exchangers. For this reason, it is necessary to further reduce the thickness of the heat exchanger constituent materials such as the working fluid path material and the fin material. The working fluid path constituent material is required to have high strength as well as sufficient brazing and corrosion resistance. Furthermore, a sacrificial anode effect is also required to protect the working fluid path constituent material. Particularly, the header plate material of the radiator is caulked between the plastic members using rubber packing after brazing. However, as the working fluid path constituent material becomes stronger, the caulked portion is repeatedly used by the refrigerant. It is easy to break fatigue by pressurizing. For this reason, fatigue fracture resistance is also required.

  For the purpose of increasing the strength, for example, it is common practice to add about 0.05 to 0.5% Mg to a 3003 alloy core material. However, since Mg contained reacts with the F component of the flux to reduce the effect of the flux and cause brazing failure, the technique of adding Mg to the core material is difficult to use. For example, it is common practice to add about 0.05 to 0.5% Mg to a 7072 alloy sacrificial anode material. However, 7072 alloy contains about 1% by mass of Zn. The head plate material of the radiator is caulked between plastic members using rubber packing after brazing. The 7072 alloy has a relatively low fatigue fracture resistance due to the influence of Zn contained, and the caulked portion is easily damaged by repeated pressurization with a refrigerant. Therefore, a technique of adding Mg to the 7072 alloy sacrificial anode material is also used. hard.

The various clad materials proposed above have the following problems.
That is, in Patent Document 1, an Al—Mn alloy for the purpose of improving pitting corrosion resistance is used for the core material, but the strength, particularly the strength after brazing is not sufficient. Moreover, the potential of the core material is not noble and the corrosion resistance is insufficient. Since the sacrificial anode material is also adjusted only in terms of corrosion resistance, the sacrificial anode material is insufficient in terms of the fatigue characteristics of the caulking portion. In addition, regarding the brazing material, the study on the fluidity of the brazing is insufficient.

  The clad material proposed in Patent Document 2 is a radiator material having a two-layer structure including a core material and a skin material as a sacrificial anode material. It does not describe the brazing material, and it does not indicate that it is necessary to adjust the flowability of the brazing to obtain proper brazing properties. The core material is an Al—Mn alloy for the purpose of corrosion resistance as in Patent Document 1, and the strength, particularly the strength after brazing, is not sufficient. Moreover, the potential of the core material is not noble and the corrosion resistance is insufficient. Furthermore, the skin material is also adjusted only from the viewpoint of pitting corrosion resistance, so that it is insufficient in terms of the fatigue characteristics of the caulking portion.

  Furthermore, since the cladding material proposed in Patent Document 3 uses an Al-Mn alloy containing Mg as a core material, when brazing using a fluoride-based non-corrosive flux, Mg and flux Reacts easily to brazing defects. In addition, as in Patent Documents 1 and 2, not only the strength, particularly the strength after brazing, is not sufficient, but the potential of the core material is not noble and the corrosion resistance is insufficient. The sacrificial anode material is also inadequate in terms of the fatigue characteristics of the caulking portion because the components are adjusted only in terms of strength improvement and corrosion resistance. As for the brazing material, a commonly used JIS4004 alloy or JIS4045 alloy is used, but in such an alloy, the Si content is 9.7 to 10.0%, and the fluidity of the brazing material becomes too good. Erosion (that is, the base material = melting of the core material) is likely to occur.

  The present invention has been devised to solve such problems, and not only exhibits high strength, particularly high strength after brazing, but also has excellent corrosion resistance and bending fatigue characteristics, Heat consisting of a clad material with a three-layer structure that is suitable and that does not cause brazing failure or erosion (melting of the base / core material) even when brazed using a fluoride-based non-corrosive flux It aims at providing the aluminum alloy brazing sheet for exchangers.

  In order to achieve the object, the aluminum alloy brazing sheet for a heat exchanger of the present invention has Si: 0.3 to 1.0% by mass, Fe: 0.3 to 0.8% by mass, Mn: 0.8 to 1 .6% by mass, Cu: 0.5 to 0.9% by mass, Mg as an impurity is regulated to 0.05% by mass or less, and the balance is an aluminum alloy composed of Al and inevitable impurities. On one side, Mg: 0.2-0.6% by mass, Zn: 0.1-0.3% by mass, and the other side by using an aluminum alloy consisting of Al and inevitable impurities as the sacrificial anode material In addition, Si: 6.5 to 8.5% by mass, Fe: 0.15 to 0.6% by mass, Mg as an impurity is regulated to 0.05% by mass or less, and the balance is Al and inevitable impurities Aluminum alloy with a three-layer structure using an aluminum alloy composed of Characterized in that an alloy cladding material.

  Moreover, the aluminum alloy brazing sheet manufacturing method for a heat exchanger according to the present invention includes Si: 0.3 to 1.0 mass%, Fe: 0.3 to 0.8 mass%, Mn: 0.8 to 1.6 mass%. %, Cu: 0.5 to 0.9 mass%, Mg as an impurity is regulated to 0.05 mass% or less, and an aluminum alloy consisting of Al and unavoidable impurities is 580 to 620 ° C. After homogenization treatment for 15 hours or / and subsequently at 440 to 490 ° C. for 1 to 6 hours, the aluminum alloy is used as a core material, and Mg: 0.2 to 0.6% by mass, Zn on one side : Aluminum alloy containing 0.1 to 0.3% by mass, the balance being Al and inevitable impurities as a sacrificial anode material, Si: 6.5 to 8.5% by mass, Fe: 0 on the other side Mg containing 15 to 0.6% by mass as impurities Restricted to 0.05 wt% or less, the balance being obtained an aluminum alloy clad material of a three-layer structure in which the aluminum alloy brazing material made of Al and unavoidable impurities.

The aluminum alloy brazing sheet for a heat exchanger made of the three-layer structure clad material according to the present invention has its components adjusted so that each of the core material, the sacrificial anode material, and the brazing material constituting the aluminum alloy brazing sheet exhibits the required characteristics. .
For this reason, it is excellent in brazing property and not only excellent in corrosion resistance even after brazing, but also maintains excellent corrosion resistance because cracks hardly occur even when repeatedly subjected to pressure. In addition, the aluminum alloy used as the core material is appropriately homogenized in advance, and an appropriate strength can be obtained particularly after brazing. Therefore, even when used in a caulking structure, the occurrence of cracks in the caulking portion is suppressed. .
Therefore, according to the present invention, it is possible to provide a suitable material for manufacturing a heat exchanger excellent in corrosion resistance and fatigue characteristics by the brazing method.

The present inventors reexamined each desired characteristic of the aluminum alloy constituting each layer of the aluminum alloy brazing sheet for a heat exchanger made of a three-layer clad material, and examined the component composition that exhibits each desired characteristic. Repeated.
As a result, first, as a core material of a three-layer structure clad material that becomes an aluminum alloy constituting a heat exchanger, Si: 0.3 to 1.0 mass%, Fe: 0.3 to 0.8 mass%, Mn : Aluminum containing 0.8 to 1.6% by mass, Cu: 0.5 to 0.9% by mass, Mg as impurities being regulated to 0.05% by mass or less, the balance being Al and inevitable impurities We have found that alloys are preferred.

The reason for limiting to such an alloy composition is as follows.
Si is an element that contributes to strength improvement. Strength is improved by forming a solid solution in the matrix or making an intermetallic compound with Mn or Fe. However, if the content is less than 0.3% by mass, the desired strength, particularly the strength after brazing, is not sufficient. On the contrary, if it is contained in a large amount exceeding 1.0% by mass, brazing diffusion is increased during brazing heating, or the melting start temperature of the core material is lowered, thereby reducing brazing properties. Become. Therefore, from the viewpoint of improving strength and securing brazing properties, the Si content is in the range of 0.3 to 1.0 mass%. Preferably it is 0.3-0.8 mass%.

  Fe contributes to hot rollability and strength improvement. And it has the effect | action which raises a melting start temperature in the aluminum alloy containing many Si and Cu. Furthermore, an intermetallic compound is formed with Mn and Si, and strength is improved. If the content is less than 0.3% by mass, not only the sufficient hot rolling property can be obtained, but also the desired strength, particularly the strength after brazing cannot be obtained. Moreover, the melting start temperature of a core material is reduced, and brazing property is reduced. On the contrary, when it exceeds 0.8 mass%, corrosion resistance will fall. On the other hand, if it exceeds 0.8% by mass, or exceeds 2.4% by mass together with Mn, a large crystallized substance appears during casting and casting cracks are likely to occur. Therefore, from the viewpoint of ensuring hot rollability and castability, and improving strength and corrosion resistance, the Fe content is in the range of 0.3 to 0.8 mass%. Preferably it is 0.4-0.7 mass%.

  Mn is dissolved in the matrix to improve the strength. And it has the effect | action which raises a melting start temperature in the aluminum alloy containing many Si and Cu. Furthermore, Mn forms an intermetallic compound with Fe and Si, and improves the strength. If the content is less than 0.8% by mass, desired strength, particularly strength after brazing cannot be obtained. Moreover, the melting start temperature of a core material is reduced, and brazing property is reduced. Conversely, if it exceeds 1.6% by mass or exceeds 2.4% by mass in combination with Fe, a large crystallized substance appears during casting, and casting cracks are likely to occur. Therefore, the Mn content is in the range of 0.8 to 1.6% by mass from the viewpoint of ensuring hot rollability and castability, and improving brazing and strength. Preferably it is 0.9-1.5 mass%.

  Cu improves strength and corrosion resistance. Cu exists as a solid solution in the matrix and contributes to strength improvement. Furthermore, the corrosion resistance is improved by making the potential of the core material noble. If the content is less than 0.5% by mass, desired strength, particularly strength after brazing cannot be obtained. Further, the potential of the core material is not noble, and the effect of improving the corrosion resistance is not exhibited. On the other hand, if it exceeds 0.9 mass%, not only the Cu-based intermetallic compound is formed at the grain boundary and the corrosion resistance is lowered, but also the melting start temperature of the core material is lowered and the brazing property is also lowered. Therefore, from the viewpoint of improving strength, corrosion resistance, or brazing property, the Cu content is set to a range of 0.5 to 0.9 mass%.

  Mg is an element that inhibits brazing. When an aluminum alloy containing Mg is brazed using an aluminum fluoride-based non-corrosive flux, the flux components F and Mg react to reduce the effect of the flux. From the viewpoint of reducing the amount of flux used, the Mg content is 0.05% by mass, preferably 0.03% by mass.

As the sacrificial anode material of the three-layer structure clad material, an aluminum alloy containing Mg: 0.2 to 0.6% by mass, Zn: 0.1 to 0.3% by mass with the balance being Al and inevitable impurities is used. I found it preferable.
The reason for limiting to such an alloy composition is as follows.

  Mg improves strength and corrosion resistance. Mg is dissolved in the matrix to improve the strength. Furthermore, the sacrificial anode function is improved by lowering the potential of the sacrificial anode material. However, if the content is less than 0.2% by mass, the potential of the sacrificial anode material is not low, and the sacrificial anode function is not exhibited. On the contrary, when it exceeds 0.6 mass%, it will exist along a grain boundary and it will become easy to occur intergranular corrosion, and corrosion resistance will fall on the contrary. Therefore, from the viewpoint of improving strength and corrosion resistance, the Mg content is in the range of 0.2 to 0.6 mass%. Preferably it is 0.3-0.5 mass%.

  Zn improves the corrosion resistance. Zn exists as a solid solution in the matrix, and improves the sacrificial anode function by lowering the potential of the sacrificial anode material. However, if the content is less than 0.1% by mass, the potential of the sacrificial anode material is not low, and the sacrificial anode function is not exhibited. On the contrary, when it exceeds 0.3 mass%, it comes to exist along the grain boundary, and when it is repeatedly used under pressure, the grain boundary becomes brittle, and cracking tends to occur. Therefore, from the viewpoint of improving corrosion resistance and repeated fatigue characteristics, the Zn content is in the range of 0.1 to 0.3% by mass. Preferably it is 0.15-0.25 mass%.

The brazing material of the three-layer clad material includes Si: 6.5 to 8.5% by mass, Fe: 0.15 to 0.6% by mass, and Mg as an impurity is regulated to 0.05% by mass or less. Then, the inventors have found that an aluminum alloy whose balance is made of Al and inevitable impurities is preferable.
The reason for limiting to such an alloy composition is as follows.

  The amount of Si contained in the brazing material greatly contributes to the brazing property as well as the thickness of the brazing material layer. Si is an element that greatly affects the fluidity of the brazing material. In the present invention, the Si content is defined from the viewpoint of brazing. When the amount of Si is less than 6.5% by mass, the fluidity of the braze is lowered, and a portion that is not brazed occurs. On the other hand, if the content exceeds 8.5% by mass, the braze fluidity increases during brazing heating and diffuses into the core material, eroding the core material (of the core material due to eutectic melting of the brazing material and the core material). The brazing property is lowered due to the difference between the heat capacities of the materials and the flow of brazing from the portion necessary for brazing at the time of cooling after brazing heating. Therefore, from the viewpoint of wax fluidity, the Si content is in the range of 6.5 to 8.5 mass%. Preferably it is 6.8-8.0 mass%.

  Fe has the effect | action which improves the hot-rollability and the fluidity | liquidity of a brazing. However, if the Fe content is less than 0.15% by mass, the brazing material will not have sufficient hot rolling properties. On the contrary, when it exceeds 0.6% by mass, the fluidity of the wax is lowered. Therefore, from the viewpoint of hot rollability and brazing fluidity, the Fe content is set to a range of 0.15 to 0.6 mass%. Preferably it is 0.2-0.55 mass%.

  Mg is an element that inhibits brazing. When an aluminum alloy containing Mg is brazed using an aluminum fluoride-based non-corrosive flux, the flux components F and Mg react to reduce the effect of the flux. From the viewpoint of reducing the amount of flux used, the Mg content is 0.05% by mass, preferably 0.03% by mass.

By the way, a brazing sheet having a three-layer structure as a header plate is required to have sufficient press formability in order to be molded before being brazed. When used after being softly tempered by annealing (hereinafter referred to as “O material tempering”), in order to have sufficient formability, it has an appropriate tensile strength and is a crystal of a brazing sheet core material. It is necessary to finely adjust the particle size.
In addition, since a brazing sheet having a tempered O material is distorted during molding by press molding or the like, a subcrystalline structure is formed in the portion during brazing heating, and erosion (melting of the core material) occurs locally. In order to prevent erosion of the brazing sheet core material, it is necessary to make the structure easy to recrystallize before melting the brazing material even in a low strain region.

In order to satisfactorily satisfy these, the brazing sheet core material is subjected to homogenization treatment to control the solid solution state of alloy elements such as Mn, Fe, Si, Cu, etc., and the intermetallic compound particles are coarsened to some extent. It is necessary to control the distribution sparsely. For this purpose, it is necessary to perform a homogenization treatment at 580 to 620 ° C. for 1 to 15 hours, or further at 440 to 490 ° C. for 1 to 6 hours.
When the homogenization treatment temperature is less than 580 ° C., fine intermetallic compounds exist at a high density. For this reason, when it uses by O material refining, it becomes a coarse crystal grain at the time of final annealing, and tensile strength will also become high. On the other hand, when the homogenization temperature is higher than 620 ° C., the intermetallic compound particles are not preferable because they are dissolved, and energy loss occurs.

Moreover, if the homogenization treatment time is less than 1 hour, the control of intermetallic compound particles is not sufficient. On the other hand, it is not preferable to perform the treatment for a long time because energy loss occurs.
Subsequently, by lowering the temperature to 440 to 480 ° C. and holding it, an element such as Mn, Si, Fe, Cu or the like dissolved in the solid precipitates, and a somewhat coarse intermetallic compound becomes more preferable. If the holding temperature is less than 440 ° C., precipitation of solid solution elements is not sufficient, and further coarsening of the intermetallic compound coarsened to some extent does not occur, and it takes too much time to cool down, resulting in energy loss. Conversely, when the temperature is higher than 480 ° C., there is no temperature difference from the previous homogenization treatment temperature, and precipitation of solid solution elements does not proceed sufficiently, so that further coarsening of the intermetallic compound coarsened to some extent does not occur. .
Further, if the temperature lowering / holding time is less than 1 hour, solid solution element precipitation is not sufficient, and the intermetallic compound particles coarsened to some extent do not become larger. On the other hand, it is not preferable to perform the treatment for a long time because energy loss occurs.

If the core material is not homogenized, the clad-rolled three-layer brazing sheet is too high in tensile strength and too large in crystal grain size, resulting in poor formability and difficulty in caulking.
The brazing sheet is provided with a brazing material and a sacrificial anode material on both sides of a core material, and is clad by hot rolling. The heating before hot rolling is usually performed at a temperature of 500 ° C. or less. The reason for selecting this temperature is that since the solidus temperature of the brazing material is about 577 ° C., it is necessary to stop at a temperature at which the brazing material is not melted. The heating temperature before hot rolling coincides with the temperature range in which the homogenization effect was not obtained because it was too low among the above-mentioned homogenization temperatures, and the homogenization was performed at a temperature lower than the predetermined value. Similarly, a fine intermetallic compound is present in the metal structure of the core material at a high density, resulting in coarse crystal grains during final annealing and a high tensile strength. That is, a preferable brazing sheet cannot be obtained.

  Below, as each layer of the three-layer structure clad material constituting the aluminum alloy brazing sheet for a heat exchanger, a clad material combining various aluminum alloys was prototyped, and an evaluation of brazing property and the like was attempted.

Example 1:
As the aluminum alloy for the core material, various alloy melts having the component compositions shown in Table 1 were melted, passed through a ceramic filter, and a slab was obtained by DC casting. The core slab was heated at 50 ° C./hr and held at 600 ° C. for 10 hours, then cooled at 50 ° C./hr and held at 450 ° C. for 5 hours, and allowed to cool.
Furthermore, the aluminum alloy for sacrificial anode materials indicated by L in Table 2 and the aluminum alloy for brazing materials indicated by R in Table 3 were individually face-cut, homogenized, and hot-rolled.

Then, after stacking the sacrificial anode material and the brazing material in various combinations as shown in Table 4 so that the cladding rate is 10% on both surfaces of the above-mentioned aluminum alloy plate for core material, both surfaces of which are chamfered, The temperature was raised at 50 ° C./hr, held at 480 ° C. for 3 hours, and then hot rolled to obtain various clad materials with a thickness of 6 mm.
Further, after cold rolling to a thickness of 1.5 mm, the temperature was raised to 400 ° C. at a rate of 50 ° C./hr and held for 2 hours, and then cooled to 100 ° C. at a cooling rate of 50 ° C./hr. The final annealing to soften was performed.

Various clad materials obtained by the above means are subjected to material tensile test, tensile test after brazing temperature heating and corrosion resistance test, brazing test, and caulking test of core as shown below. evaluated.
(1) Material tensile test A JIS No. 5 test piece was cut out from the clad material in the rolling direction, and a tensile test was performed to measure the tensile strength and the yield strength.

(2) Tensile test and corrosion resistance test after brazing The clad material was heated at a rate of 25 ° C./hr in a nitrogen gas atmosphere at a rate of 600 ° C. for 3.5 minutes assuming brazing conditions. Then, heat treatment was performed to cool to room temperature at a cooling rate of 100 ° C./hr. Thereafter, a JIS No. 5 test piece was cut out in the rolling direction, and a tensile test was performed to measure the tensile strength and the yield strength. Moreover, after masking the brazing filler metal surface of the heat-treated clad material, it was immersed in a room temperature solution of Cl ⁻ : 195 ppm, SO ₄ ²⁻ : 60 ppm, Cu ²⁺ : 1 ppm, Fe ²⁺ : 30 ppm for 4 weeks. Then, the maximum pitting depth was measured by the depth of focus method of an optical microscope. Furthermore, the presence or absence of intergranular corrosion was also observed.

(3) Brazing property test After solvent degreasing, JIS A3003 aluminum alloy plate coated with ² g / m ^{2 of} non-corrosive fluoride flux composed of a mixed composition of KAlF ₄ and K ₃ AlF _{6 on} each surface was used as a substrate. The plates having a height of 25 mm and a length of 40 mm obtained according to the examples and comparative examples were fixed vertically to form a so-called inverted T-shaped test shape and brazed under the following conditions. In a nitrogen gas atmosphere furnace, it was heated at a rate of temperature increase of 50 ° C./min, held at 600 ° C. for 5 minutes, then taken out of the brazing furnace and air cooled to room temperature.
After cooling, the brazed surface was observed to examine the erosion state of the core material. Slightly eroded core material was evaluated as good (◯), and core material eroded severely and eutectic between the brazing material and the core material was marked as poor (×).

(4) Caulking test of core After brazing, the header plate of the radiator core was visually observed for cracking of the header plate when it was caulked with a resin tank member using rubber packing. . The thing without a crack was made into good ((circle)), and the thing with which the crack generate | occur | produced was made into defect (x).
The radiator core was manufactured by applying 2 g / m ^{2 of a} non-corrosive fluoride-based flux comprising a mixed composition of KAlF ₄ and K ₃ AlF ₆ to each surface, and then in a nitrogen gas atmosphere furnace at 25 ° C. / Heating was performed at a temperature rising rate of 1 minute, and when the temperature reached 600 ° C., holding was performed for 5 minutes, followed by brazing by air cooling at a cooling rate of 100 ° C./minute. In addition, the radiator core is formed by processing the brazing sheet of the embodiment as a header plate, using a JIS 3N03 alloy plate having a thickness of 70 μm as a formed fin material, using a flat tube material as a JIS 3003 alloy core material, and JIS 3003 alloy core material. A B-type tube clad with 4045 alloy brazing material and JIS 7072 alloy sacrificial anode material was used.
Each evaluation test result is shown together in Table 4.

As can be seen from the results shown in Table 4, the brazing sheets of Invention Examples 1 to 3 in which the core material, the brazing material, and the sacrificial anode material each made of an alloy within the scope of the present invention are clad rolled have appropriate strength before and after brazing. No cracks were generated in the bent portion during caulking of the core, the brazing property in the inverted T-shaped brazing test was good, and the corrosion resistance was also excellent.
In contrast, Comparative Example No. No. 1 brazing sheet is not suitable as a brazing sheet for a heat exchanger that requires low strength before and after brazing because the Si content of the core material is too small.

Comparative Example No. The brazing sheet 2 had a too high Si content in the core material, so that the strength before brazing was too high and the moldability was not good. Moreover, even after brazing, the strength is too high, so that not only cracking occurs at the time of caulking the core, but also brazing sheets for heat exchangers, coupled with a decrease in brazing properties due to the core Si being too high. Not suitable as.
Comparative Example No. The brazing sheet of No. 3 is not only insufficient in strength before brazing due to the low Fe content of the core material, but also lacks strength after brazing, and requires a high strength brazing sheet for heat exchangers. Not suitable as. In addition, the hot rolling property was poor, and bending occurred during hot rolling.

Comparative Example No. In No. 4, since the core material had too much Fe content, a giant crystallized product was generated during casting and cracking occurred during casting.
Comparative Example No. The brazing sheet of No. 5 is not suitable as a brazing sheet for a heat exchanger that requires low strength before and after brazing because the Cu content of the core material is too small. Furthermore, since the maximum pitting corrosion depth was deep in the corrosion resistance test, it is not suitable as a brazing sheet for a heat exchanger.
Comparative Example No. The brazing sheet of No. 6 has too much Cu content in the core, so that not only is the strength before brazing too high and the moldability is poor, but the strength after brazing is too high and cracks occur when caulking the core. It was. Also, brazability is not good. Furthermore, since the maximum depth is deep in the corrosion resistance test and intergranular corrosion is also observed, it is not suitable as a brazing sheet for a heat exchanger.

Comparative Example No. The brazing sheet of No. 7 is not suitable as a brazing sheet for a heat exchanger that requires low strength before and after brazing because the Mn content of the core material is too small, and requires high strength. Also, brazability is not good. Furthermore, since the maximum depth is slightly deep in the corrosion resistance test, it is not suitable as a brazing sheet for a heat exchanger.
Comparative Example No. In No. 8, since the Mn content of the core material was too large, a giant crystallized product was generated during casting, and cracks occurred during casting.

Example 2:
As an aluminum alloy for the core material, a molten alloy having a component composition indicated by A in Table 1 was melted, passed through a ceramic filter, and a slab was obtained by DC casting. The core slab was heated at 50 ° C./hr and held at 600 ° C. for 10 hours, then cooled at 50 ° C./hr and held at 450 ° C. for 5 hours, and allowed to cool.
Furthermore, the various aluminum alloys for sacrificial anode materials shown in Table 2 and the aluminum alloy for brazing materials shown by R in Table 3 were individually face-cut, homogenized, and hot-rolled.

And after stacking the sacrificial anode material and the brazing material in various combinations as shown in Table 5 so that the clad rate is 10% on both surfaces of the above-mentioned aluminum alloy plate for core material, both surfaces of which are chamfered, The temperature was raised at 50 ° C./hr, held at 480 ° C. for 3 hours, and then hot rolled to obtain various clad materials with a thickness of 6 mm.
Further, after cold rolling to a thickness of 1.5 mm, the temperature was raised to 400 ° C. at a rate of 50 ° C./hr and held for 2 hours, and then cooled to 100 ° C. at a cooling rate of 50 ° C./hr. The final annealing to soften was performed.
For the various clad materials obtained by the above means, the repeated pressurization test as shown below and the corrosion resistance test after heating at the same brazing temperature as in Example 1 are performed to evaluate the bending fatigue strength and the corrosion resistance after brazing. did.

(5) Repeated pressurization test Repeated pressurization with water pressure using a brazing core, and evaluation of cracks and leaks in the caulked part between the header plate and rubber parts using a rubber packing went. The radiator core was produced by applying 2 g / m ^{2 of a} non-corrosive fluoride flux composed of a mixed composition of KAlF ₄ and K ₃ AlF _{6 on} each surface, and then in a nitrogen gas atmosphere furnace at 25 ° C./min. After heating at a temperature rising rate of 600 ° C. and holding at 600 ° C. for 5 minutes, brazing was performed by air cooling at a cooling rate of 100 ° C./min. In addition, the radiator core is formed by processing the brazing sheet of the embodiment as a header plate, using a JIS 3N03 alloy plate having a thickness of 70 μm as a formed fin material, using a flat tube material as a JIS 3003 alloy core material, and JIS 3003 alloy core material. A B-type tube clad with 4045 alloy brazing material and JIS 7072 alloy sacrificial anode material was used.
The evaluation results are also shown in Table 5.

As can be seen from the results shown in Table 5, the brazing sheet of Example 4 of the present invention in which the core material, the brazing material, and the sacrificial anode material each made of an alloy within the scope of the present invention are clad rolled has a number of repetitions in the repeated pressure test. High bending fatigue strength. It also has excellent corrosion resistance.
In contrast, Comparative Example No. Since the brazing sheet of No. 9 had too much Zn content in the sacrificial anode material, cracking occurred at a stage where the number of repetitions was small in the repeated pressure test, and the bending fatigue strength was not sufficient. For this reason, it is not suitable as a brazing sheet for a heat exchanger.
Comparative Example No. No. 10 brazing sheet is not suitable as a brazing sheet for a heat exchanger because the sacrificial anode material has too little Zn content, and the maximum pitting corrosion depth becomes deep in the corrosion resistance test.
Comparative Example No. Since the brazing sheet of No. 11 has too much Mg content in the sacrificial anode material, the maximum pitting corrosion depth is deep in the corrosion resistance test, and intergranular corrosion is recognized, and is not suitable as a brazing sheet for a heat exchanger.
Comparative Example No. No. 12 was not suitable as a brazing sheet for a heat exchanger because the Mg content of the sacrificial anode material was too small, and the maximum pitting corrosion depth was increased in the corrosion resistance test.

Example 3:
As the aluminum alloy for the core material, various alloy melts having the component compositions shown in Table 1 were melted, passed through a ceramic filter, and a slab was obtained by DC casting. The core slab was heated at 50 ° C./hr and held at 600 ° C. for 10 hours, then cooled at 50 ° C./hr and held at 450 ° C. for 5 hours, and allowed to cool.
Furthermore, the aluminum alloy for sacrificial anode materials indicated by L in Table 2 and the various aluminum alloys for brazing materials shown in Table 3 were individually face-cut, homogenized, and hot-rolled.

And after stacking the sacrificial anode material and the brazing material in various combinations as shown in Table 6 so that the clad rate is 10% on both surfaces of the above-mentioned aluminum alloy plate for core material, both surfaces of which are chamfered, The temperature was raised at 50 ° C./hr, held at 480 ° C. for 3 hours, and then hot rolled to obtain various clad materials with a thickness of 6 mm.
Further, after cold rolling to a thickness of 1.5 mm, the temperature was raised to 400 ° C. at a rate of 50 ° C./hr and held for 2 hours, and then cooled to 100 ° C. at a cooling rate of 50 ° C./hr. The final annealing to soften was performed.
For the various clad materials obtained by the above means, the core brazing test as shown below and the brazing test using the same inverted T-shaped test piece as in Example 1 were conducted, and the core brazing performance and inverted T-shaped brazing were performed. The applicability was evaluated.

(6) Brazing test of core After applying 2 g / m ^{2 of a} non-corrosive fluoride-based flux composed of a mixed composition of KAlF ₄ and K ₃ AlF ₆ to each surface, it is 25 ° C./min in a nitrogen gas atmosphere furnace. After heating at a temperature rising rate of 600 ° C. and holding at 600 ° C. for 5 minutes, brazing was performed by air cooling at a cooling rate of 100 ° C./min.
After cooling, the brazing state of the fitting portion of the header plate and the tube and the mating portion of the B-type tube was visually observed and observed in a macro section. The fillet is uniformly formed and the core material is not eroded (melting of the core material by eutectic melting of the brazing material and the core material), and the erosion recess (the brazing material and the core material If there is no recess formed due to melting and outflow of the core material by eutectic, it is judged as good (◯), the fillet is not formed uniformly, the core material is eroded, or for example, FIG. As shown to a), what the erosion recessed part was remarkable in the mating part of a B type tube was made into defect (x). FIG. 1B shows a normal product. The radiator core was formed by processing the brazing sheet of the example as a header plate, a JIS 3N03 alloy plate having a thickness of 70 μm as a formed fin material, a flat tube material, and a JIS 3003 alloy core material as JIS. A B-type tube clad with 4045 alloy brazing material and JIS 7072 alloy sacrificial anode material was used.
The evaluation results are also shown in Table 6.

As can be seen from the results shown in Table 6, the brazing sheet of Invention Example 5 in which the core material, the brazing material and the sacrificial anode material made of an alloy within the scope of the present invention are clad rolled is the core shape and the inverted T-shaped test piece shape. In each of the brazing tests, sufficient brazing is performed, and the brazing property is excellent.
In contrast, Comparative Example No. In the brazing sheet of No. 13, no erosion was observed in the brazing of the inverted T-shaped specimen, but the braze fluidity was not sufficient when brazing the core because of the excessive Fe content of the brazing material. Some parts were not brazed due to this. For this reason, it is not suitable as a brazing sheet for a heat exchanger.
Comparative Example No. In the brazing sheets of 14 to 16, the Si content of the brazing material was too high, so that not only erosion was observed even in the brazing of the inverted T-shaped test piece, but also the brazing fluidity of the brazing of the core shape was It became too high and an erosion recess was observed at the mating part of the B-type tube, and the brazing property was not sufficient. For this reason, it is not suitable as a brazing sheet for a heat exchanger.

Example 4:
As an aluminum alloy for the core material, a molten alloy having a component composition indicated by B in Table 1 was melted, passed through a ceramic filter, and a slab was obtained by DC casting.
In Example 6 of the present invention, this slab for core material was heated at 50 ° C./hr and held at 600 ° C. for 10 hours, then cooled at 50 ° C./hr and held at 450 ° C. for 5 hours. And allowed to cool. In Inventive Example 7, the concentric slab was heated at 50 ° C./hr and held at 600 ° C. for 10 hours, and then discharged from the homogenization furnace and air-cooled.
On the other hand, Comparative Example No. In No. 17, the core slab was heated at 50 ° C./hr and held at 480 ° C. for 10 hours, and then discharged from the homogenization furnace and air-cooled. Further, Comparative Example No. In No. 18, the homogenization process of this core material slab was not performed.

Further, the aluminum alloy for sacrificial anode material indicated by L in Table 2 and the aluminum alloy for brazing material indicated by R in Table 3 are each individually face-ground, homogenized, and hot-rolled to face both surfaces. The both surfaces of the aluminum alloy plate for core material are stacked so that the cladding ratio is 10%, and then heated at 50 ° C./hr and kept at 480 ° C. for 3 hours, and then clad rolled by hot rolling. As a result, various clad materials having a thickness of 6 mm were obtained.
Then, after further cold rolling to 1.5 mm thickness, the temperature is raised at a rate of 50 ° C./hr, held at 400 ° C. for 2 hours, and then cooled to 100 ° C. at a cooling rate of 50 ° C./hr. To soften.
Using the clad materials of the present invention examples and comparative examples obtained by these means as brazing sheets, the same tensile strength as in Example 1, tensile strength after brazing temperature heating, and caulking crack of the core were evaluated.
The results are shown in Table 7.

As can be seen from the results shown in Table 7, the brazing sheets of Examples 6 and 7 of the present invention obtained by clad rolling the core material, the brazing material and the sacrificial anode material each made of an alloy within the scope of the present invention were brazed. The tensile strength before brazing and the tensile strength after brazing are appropriate, and there is no caulking crack of the core, and it is excellent as a brazing sheet for a heat exchanger.
In contrast, Comparative Example No. The brazing sheet of No. 17 was not good in moldability because the homogenization temperature of the core material was too low, the strength before brazing was high, and the crystal grain size of the core material was too large. Further, not only erosion is partially recognized in the header plate after brazing heating, but also caulking cracks occur in the core. For this reason, Comparative Example No. No. 17 brazing sheet is not suitable as a material for the heat exchanger to be brazed.
Comparative Example No. Since the brazing sheet of No. 18 was not subjected to homogenization treatment of the core material, the strength before brazing was high, and the crystal grain size of the core material was coarse, and the moldability was not good. Further, not only erosion is partially recognized in the header plate after brazing heating, but also caulking cracks occur in the core. For this reason, Comparative Example No. No. 17 brazing sheet is not suitable as a material for the heat exchanger to be brazed.

Partial cross-sectional view explaining the state of formation of erosion recesses that are likely to be formed at the mating part of the B-type tube when brazing the heat exchanger using the B-type tube, where (b) is normal

Claims (2)

  Si: 0.3-1.0% by mass, Fe: 0.3-0.8% by mass, Mn: 0.8-1.6% by mass, Cu: 0.5-0.9% by mass, Mg as an impurity is regulated to 0.05% by mass or less, and the balance is made of an aluminum alloy composed of Al and inevitable impurities, with Mg: 0.2 to 0.6% by mass and Zn: 0 on one side. 0.1% to 0.3% by mass of aluminum alloy consisting of Al and unavoidable impurities as a sacrificial anode material, Si: 6.5 to 8.5% by mass, Fe: 0.15 on the other surface It is composed of an aluminum alloy clad material having a three-layer structure including Mg alloy as an impurity and containing 0.05 mass% or less, and the balance being Al and an inevitable impurity aluminum alloy. Aluminum alloy brazing sheet for heat exchangers Door.   Si: 0.3-1.0% by mass, Fe: 0.3-0.8% by mass, Mn: 0.8-1.6% by mass, Cu: 0.5-0.9% by mass, Mg alloy as an impurity is regulated to 0.05% by mass or less, and the balance of aluminum alloy consisting of Al and inevitable impurities is 580 to 620 ° C. for 1 to 15 hours, and / or further 440 to 490 ° C. for 1 to 6 hours. The aluminum alloy is used as a core material, and Mg: 0.2 to 0.6 mass%, Zn: 0.1 to 0.3 mass% is contained on one side, and the balance is Al. In addition, an aluminum alloy composed of inevitable impurities is used as a sacrificial anode material, and Si: 6.5 to 8.5% by mass, Fe: 0.15 to 0.6% by mass on the other side, and Mg as an impurity. Restricted to 0.05% by mass or less, with the balance being Al and inevitable impurities Above aluminum alloy brazing sheet manufacturing method, characterized in that to obtain an aluminum alloy clad material of the three-layer structure um alloy and brazing material.

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