JP2003027165A - Aluminum alloy clad plate for heat exchanger having excellent erosion resistance and formability - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an aluminum alloy clad plate which prevents the occurrence of erosion in the boundaries between a core material and brazing filler metals and has excellent formability. SOLUTION: The aluminum alloy clad plate 1 is obtained by cladding brazing filler metals 3 and 4 consisting of an Al-Si based aluminum alloy to both sides of a core material 2 consisting of an Al-Mn based aluminum alloy. The 0.2% proof stress of the clad plate 1 is controlled to 130 to 290% to the proof stress of a stock material. The core material 2 has a composition containing, by mass, 0.05 to 0.3% Cu, and the balance Al, Mn and Ti with inevitable impurities. At least one of the brazing filler metals 3 and 4 has a composition containing 7 to 13% Si and 1 to 10% Zn, and the balance Al with inevitable impurities.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an aluminum alloy clad material for a heat exchanger, which has excellent erosion resistance and formability, and in particular, is manufactured by molding a brazing sheet having a brazing material on the outer surface side (air side). The present invention relates to an aluminum alloy clad material formed by laminating and brazing laminated plates.

[0002]

2. Description of the Related Art Conventionally, as a clad material for an evaporator (plate), an Al-Mn-based aluminum alloy such as JIS3003 is usually used as a core material in terms of formability, and both surfaces of the core material are made of Al-Si-based aluminum alloy. An aluminum alloy clad material having a three-layer structure formed by clad brazing material is used. Hereinafter, such an aluminum alloy clad material having a three-layer structure will be simply referred to as “clad material”.

In forming such a clad material, in general,
Although an O material (JIS H0001) having good formability is used, it is known that the residual work strain generated by the dislocation during molding of the clad material affects the erodibility of the molten brazing material.

[0004]

That is, when the degree of residual working strain of the clad material is insufficient as a driving force for causing recrystallization of the core material when brazing the clad material. In addition, even if a relatively high temperature rise process of about 600 ° C. is performed during brazing, subgrain boundaries remain, and so-called “erosion” occurs in which the molten brazing filler metal erodes the core material. Become.

When such erosion occurs, the solidified portion formed by solidifying the molten brazing material in the clad material reaches the core material, and the solidified portion preferentially advances corrosion. Since it is formed, the corrosion resistance of the clad material deteriorates. As a conventional method for preventing the occurrence of such erosion, there are the following techniques, for example.

(1) Japanese Patent Laid-Open No. 153048/1990 discloses aluminum brazing obtained by subjecting a clad material composed of an aluminum alloy core material and an aluminum alloy brazing material to hot rolling, cold rolling and annealing. In the production of the sheet, after the annealing, cold rolling with a working rate of 5 to 15% is performed, and then strain relief annealing is performed at a temperature of 145 to 195 ° C. to prevent subgrains from remaining during clad. A method for suppressing the occurrence of erosion is disclosed.

(2) Japanese Patent Laid-Open No. 7-41919 discloses that
An aluminum alloy having a predetermined composition is used as a core material, a brazing material made of an Al-Si-based aluminum alloy is provided on one surface of the core material, and an aluminum alloy of which the content of Zn, Mg, Si, Fe, and Cu is regulated on the other surface. In the production of a brazing sheet in which a sacrificial anode skin material is clad, the ingot of the core material, the brazing material and the skin material are hot-rolled at a temperature of 550 ° C. or less, and the rolling ratio and the rolling reduction after intermediate annealing are regulated. A method for preventing the occurrence of erosion by performing final rolling and then performing final partial annealing in which the annealing temperature is regulated is disclosed.

(3) In US Pat. No. 045686964, a clad material formed by clad a brazing material in a core material (H material) made of an aluminum alloy forms a predetermined residual working strain in the core material. Thus, a method for preventing the occurrence of erosion by maintaining the driving force for recrystallization at the time of clad and further setting the rolling rate of the finish cold rolling of this clad material to 3 to 20% is disclosed.

However, these conventional methods for preventing the occurrence of erosion have a problem that the formability (elongation, Erichsen value, etc.) is lowered. Therefore, an object of the present invention is to provide an aluminum alloy clad material for an evaporator, which prevents erosion that occurs at the interface between the core material and the brazing material and has excellent formability.

[0010]

In order to solve the above-mentioned problems, the inventors of the present invention have proposed a method of forming an aluminum alloy clad material (three-layer material) having a three-layer structure in which a brazing material is clad on both surfaces of a core material. The relationship between the yield strength of the core material, the chemical composition of the core material and the brazing material, and the occurrence of erosion and the formability of the aluminum alloy clad material was investigated, and various examinations were made on measures for improving erosion resistance and formability. I did.

As a result, the 0.2% proof stress of the core material is set within a predetermined range, and the chemical compositions of the brazing material and the core material clad on the outer (air side) surface of the core material are restricted within the predetermined range. As a result, it is possible to properly form the residual processing strain that serves as a driving force that promotes the recrystallization of the structure of the clad portion, and prevent the erosion that occurs at the interface between the brazing material and the core material included in the three-layer material. At the same time, they found that the moldability of the above-mentioned three-layer material could be ensured, and the present invention was created.

That is, the aluminum alloy clad material for a heat exchanger according to claim 1 of the present invention for solving the above-mentioned problems is a core material made of an Al-Mn-based aluminum alloy. An aluminum alloy clad material obtained by clad with a brazing material composed of an alloy, wherein the material of the aluminum alloy clad material is defined as a load per unit cross-sectional area that causes a permanent elongation of 0.2%. 2% proof stress σ ₁ is JIS
1.3 × with respect to the proof stress σ ₂ of the O material of the aluminum alloy clad material specified by 0001
σ ₂ ≦ σ ₁ ≦ 2.9 × σ ₂ and the core material is
Contains Cu in an amount of 0.05 to 0.3% by mass, and balances Al and M
n-Ti and an Al-Mn-based aluminum alloy containing unavoidable impurities, and at least one of the brazing materials provided on both surfaces of the core material contains Si of 7 to 13
It is characterized in that it is made of an aluminum alloy containing 1% to 10% by mass of Zn and 1% to 10% by mass of Zn, with the balance being Al and unavoidable impurities.

According to the first aspect, Al--Mn
On both sides of the core material composed of aluminum alloy
In an aluminum alloy clad material obtained by clad a brazing material composed of a Si-based aluminum alloy, the range of 0.2% proof stress of the material of this aluminum alloy clad material is based on the proof stress of O material of this aluminum alloy material. In addition to the optimization, the chemical composition of the core material and the brazing material contained in the aluminum alloy clad material was set to an appropriate range, so that the residual processing strain, which is a driving force for promoting the recrystallization of the structure of the clad portion, is appropriately formed. As a result, erosion can be prevented and formability (elongation, Erichsen value, etc.) can be maintained at the same time.

Further, since the brazing filler metal obtained by adding Zn to the Al-Si based aluminum alloy is clad on one surface of the core member of the Al-Mn based aluminum alloy, corrosion resistance due to the sacrificial anode effect is imparted to the core member. be able to.

An aluminum alloy clad material for a heat exchanger according to a second aspect is the aluminum alloy clad material according to the first aspect, wherein the core material is made of an aluminum alloy further containing 0.2 to 1.0 mass% of Si. To do. According to the second aspect, the formability of the core material and thus the aluminum alloy clad material can be further improved.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The present invention is not limited to this embodiment. FIG. 1 shows an aluminum alloy clad material 1 having a three-layer structure according to the present invention.
It is a figure which shows the structure of. As shown in FIG. 1, the aluminum alloy clad material 1 according to the present invention comprises a core material 2
And a brazing material 3 on the outer surface side (air side) and a brazing material 4 on the inner surface side (refrigerant passage side).

In the aluminum alloy clad material 1 according to the present invention, the core material 2 made of an Al--Mn type aluminum alloy is used in order to impart predetermined strength and residual working strain and to ensure predetermined corrosion resistance. Regulations are set on the amounts of the components contained and the amounts of the components contained in the brazing filler metal 3 provided on the outer side (air side) of the core material 2. The content of each component added to the core material 2 and the brazing material 3 will be described below.

<< Cu Content of Core Material 2: 0.05-0.
3% by mass >> Aluminum alloy clad material 1 according to the present invention
In the core material 2 included in the core material 2, the strength of the core material 2 is improved, and the potential of the core material 2 is noble with respect to the brazing material 3 on the outer surface side (air side) and the brazing material 4 on the inner surface side (refrigerant passage side),
Cu is added in the range of 0.05 to 0.3 mass% in order to improve the corrosion resistance. The amount of Cu is 0.05% by mass
If it is less than the above range, the effect of corrosion resistance is not sufficient, which is not preferable. On the other hand, if the amount of Cu exceeds 0.3% by mass, the formability (elongation, Erichsen value, etc.) of the core material 2 is impaired, which is not preferable. This phenomenon is caused by the H
It becomes remarkable when the material is used.

The reason why such an amount of Cu hinders the formability of the core material 2 is 0.2% of the core material 2 which is defined as a load per unit cross-sectional area which causes a permanent elongation of 0.2%. strength sigma ₁ is for strength sigma ₂ with O material core 2, tissue core 2 having a _{1.3 × σ 2 ≦ σ 1 ≦} 2.9 × σ 2 the relationship, i.e. dislocations integrated part Or, in an aluminum alloy having a structure in which sub-grain boundaries remain, it is presumed that the solid solution Cu in the aluminum matrix acts to hinder the movement of dislocations, resulting in deterioration of the formability of the core material 2. To be done.

<< Mn content of core material 2: 0.5 to 2.0
% By mass >> Mn is contained in the core material 2 contained in the aluminum alloy clad material 1 according to the present invention.
By generating a precipitate of an n-based alloy and dispersing the precipitate of the Al-Mn-based alloy in the core material 2, the strength of the core material 2 after brazing is increased and the potential of the core material 2 is made noble. The content of Mn is preferably 0.5 to 2.0 mass% in order to increase the potential difference between the material and the corrosion resistance. The reason is that if the Mn content is less than 0.5% by mass, the effect of increasing the strength and corrosion resistance of the core material 2 after brazing is small, and the Mn content is 2.0% by mass.
This is because if it exceeds, the amount of coarse crystallized substances of the Al-Mn-based alloy increases and the workability deteriorates.

<< Ti Content of Core Material 2: 0.1-0.3
% By mass >> The core material 2 included in the aluminum alloy clad material 1 according to the present invention has an appropriate corrosion resistance when the core material 2 is cast by appropriately maintaining the Ti concentration distribution in the approximately central portion of the ingot in the plate thickness direction. Ti is added for improvement. That is, Ti is dispersed in a layered form in which regions having a relatively high Ti concentration and regions having a relatively low Ti concentration are alternately distributed in the plate thickness direction of the ingot, and a region having a relatively low Ti concentration is preferential to a region having a high Ti concentration. Since the effect of layering the corrosion form is imparted to the ingot by corroding, the progress of corrosion in the plate thickness direction of the ingot is suppressed, which contributes to the improvement of the corrosion resistance of the ingot. The content of Ti is preferably 0.1 to 0.3% by mass. The reason is that the content of Ti is 0.1% by mass.
If it is less than 1.0, the effect of improving the corrosion resistance is small and the content of Ti is 0.
This is because if it exceeds 3% by mass, casting becomes difficult, and the workability deteriorates, making it difficult to produce a desired cast material.

<< Si Content of Core Material 2 >> The core material 2 contained in the aluminum alloy clad material 1 according to the present invention may contain Si in an amount of 0.1% for the purpose of improving the formability of the aluminum alloy clad material 1. You may add in the range of 2-1.0 mass%. If the Si content is less than 0.2% by mass, the effect of improving the formability of the clad material 1 is small, and conversely, if the Si content exceeds 1.0% by mass, the melting point of the core material 2 decreases and Since the core material 2 itself included in the alloy clad material 1 causes burning in brazing, it is preferable to set the content to 1.0 mass% or less.

The reason why Si can improve the formability of the aluminum alloy clad material 1 is that Si is
By adding 0.2% by mass or more, it is possible to more uniformly disperse and precipitate the Mn-Si compound, the Al-Mn-Si compound, etc. contained in the core material 2. Is. That is, although these precipitates are formed in a substantially particle shape and have the effect of pinning dislocations in the aluminum alloy clad material, when these precipitates are more uniformly dispersed, they are localized. Since this pinning effect is dispersed and deformation is not concentrated locally, it is possible to deform more uniformly,
It is considered that the moldability is improved. As a result, the dislocations within the crystal grains of the core material 2 contained in the aluminum alloy clad material 1 are uniformly dispersed and moved, and the uniformity of elongation of the aluminum alloy clad material 1 is increased and the formability is improved. Come to do.

<< Si content of brazing filler metal 3 on the outer surface side (air side): 7 to 13% by mass >> The brazing filler metal 3 contained in the aluminum alloy clad material 1 according to the present invention has strength after brazing. In order to improve, Si is contained by 7 to 13 mass%. If the Si content is less than 7% by mass, the fluidity of the brazing material will be deteriorated and the brazing property will be impaired. If it exceeds 13% by mass, the melting temperature of the brazing material 3 will be lowered, which is not preferable.

<< Zn content of brazing material 3 on the outer surface side (air side): 1 to 10 mass% >> The brazing material 3 contained in the aluminum alloy clad material 1 according to the present invention is sacrificed with respect to the core material 2. Zn is 1 to 1 so that the effect as an anode is exhibited.
10 mass% is contained. That is, this Zn is the core material 2
It is an essential element for maintaining the corrosion resistance of the outer surface side (air side) of the above at a required level. If the content of Zn is less than 1% by mass, the above effect is not sufficiently exerted, and if it exceeds 10% by mass, Zn is concentrated in the fillet part generated at the outer surface side joint part after brazing and the Zn content of the fillet part The amount of self-corrosion increases, and as a result, the life of the joint portion on the outer surface side is shortened, which is not preferable.

The structure of the brazing material 4 is not particularly limited as long as it does not promote erosion of the aluminum alloy clad material 1 or impair formability and corrosion resistance.

<< Amount of Residual Working Strain of Aluminum Alloy Clad Material 1 >> The material of the aluminum alloy clad material 1 according to the present invention is defined as a load per unit cross-sectional area that causes a permanent elongation of 0.2%. The 2% proof stress σ ₁ is within a range of 130% to 290% with respect to the proof stress σ ₂ of the O material of the aluminum alloy clad material 1. If the proof stress σ ₁ is less than 130% of the proof stress σ ₂ , a sufficient amount of residual processing strain is obtained as a driving force that promotes recrystallization in the structure of the cladding due to the temperature rise during brazing. Therefore, the effect of suppressing the occurrence of erosion cannot be sufficiently obtained, which is not preferable. On the other hand, if it exceeds 290%, the degree of work hardening of the aluminum alloy clad material 1 becomes excessive, and even if the amount of Cu contributing to hardening is reduced to 0.3% or less, its formability is greatly impaired. Molding becomes difficult, which is not preferable.

<< Inevitable Components >> In addition to the above-mentioned components, the core material 2 contained in the aluminum alloy clad material 1 according to the present invention is an unavoidable component known in the art within a range that does not impair the effects of the present invention. Can include an optional ingredient.

The aluminum alloy clad material 1 according to the present invention as described above comprises the core material 2 and the brazing material 3 on the outer surface side (air side).
The aluminum alloy forming the brazing filler metal 4 on the inner surface side (refrigerant passage side) is ingot-cast by, for example, semi-continuous casting, subjected to homogenization treatment if necessary, and then hot-rolled to a predetermined thickness, and then these It is manufactured by a process of combining the above materials, forming a clad material by hot rolling according to a conventional method, finally performing cold rolling to a predetermined thickness, and then annealing if necessary.

[0030]

EXAMPLES Examples of the aluminum alloy clad material according to the present invention will be described below. Table 1 shows the structure of the test piece (Examples A1 to A5) of the core material 2 contained in the aluminum alloy clad material 1 according to the present invention shown in FIG. 1 and the test piece of the core material that does not satisfy the requirements of the present invention (comparison). 10 shows the configurations of Examples A6 to A9).

[0031]

[Table 1]

That is, in all of the core materials 2 of Examples A1 to A5 satisfying the requirements of the present invention, the contents of Cu and Si are within the range regulated by the present invention, and the balance is aluminum and Al which is inevitable impurities. -Mn-based aluminum alloy. In Comparative Examples A6 to A9 which do not satisfy the requirements of the present invention, Comparative Example A6 has a Si content less than the lower limit of the range regulated by claim 2 of the present invention, and Comparative Example A7 contains Cu. The amount is made larger than the upper limit value of the range regulated by claim 1 of the present invention, the comparative example A8 makes the Cu content smaller than the lower limit value of the range regulated by claim 1 of the present invention, and the comparative example A9 is The content of Si is set to be larger than the upper limit value of the range regulated by claim 2 of the present invention, and the balance is made of aluminum and an Al-Mn-based aluminum alloy containing unavoidable impurities.

Table 2 shows the constitution of the test piece (Example: C2, C3) of the outer (air side) brazing filler metal 3 contained in the aluminum alloy clad material 1 according to the present invention shown in FIG. 1 and the necessity of the present invention. It is a structure of a test piece (Comparative Example: C1) of an outer (air side) brazing material that does not satisfy the conditions. That is, in both Example C2 and Example C3, Si and Z
The content of n is within the range regulated by claim 1 of the present invention,
The balance is made of Al and an Al-Si-based aluminum alloy containing unavoidable impurities. In addition, Comparative Example C1
The content of Si is set within the range regulated by claim 1 of the present invention,
Substantially free of Zn (Zn less than detection limit)
It is composed of an Al-Si based aluminum alloy.

[0034]

[Table 2]

Table 3 shows Examples A1 to A5 of the core material 2 and Example C of the outer (air side) brazing material 3 shown in Table 1 and Table 2, respectively.
2, Example C3, Comparative Examples A6 to A9 of the core material 2, and Comparative Example C1 of the outer side (air side) brazing material 3 were appropriately combined to produce an aluminum alloy clad material 1 as shown in FIG. The composition of the material and the results of various characteristic evaluations are shown. It should be noted that, for the core material 2 shown in Table 1, Table 2
The brazing filler metal 3 shown in Table 1 is clad by hot rolling with the clad ratio set to about 10% on one side, and then subjected to predetermined cold rolling and annealing to obtain the plate thickness shown in Table 3, and
A test material having a 0.2% yield strength (compared to the yield strength of the O material of the aluminum alloy clad material 1) was obtained.

[0036]

[Table 3]

Of the test materials shown in Table 3, the examples according to the present invention are D1, D2, D4 and D5, and the comparative examples D3 and D6 to D11 which do not satisfy the requirements of the present invention are respectively
The Si or Cu content of the core material is outside the range regulated by the present invention, or the 0.2% proof stress of the aluminum alloy clad material 1 is outside the range regulated by claim 1 of the present invention.

The moldability evaluations shown in Table 3 were evaluated by performing Erichsen test A method (JISZ2247) and tensile test (JISZ2201) on each test material. In the above-mentioned tensile test, 16% or more of those are "A (excellently good)", and 14% or more of are "O (good)", 1
Those less than 4% were evaluated as "x (bad)". According to the Erichsen test A method, a test height of 6.0 mm or more is “Excellent (excellent)”, a test height of 5.0 mm or more is “◯ (good)”, and a test height of less than 5.5 mm is “Excellent”. ×
(Poor) "was evaluated.

The evaluation of erosion resistance shown in Table 3 was carried out by measuring the cold rolling rate (sheet thickness reduction rate) of 7 for each test material.
%, 10%, and after cold rolling, brazing (6
The erosion depth (depth at which the brazing material penetrates from the interface between the original brazing material and the core material to the core material side) of one side of the aluminum alloy clad material that has been kept at 00 ° C for 2 minutes) is measured, and this erosion depth is measured. Those having a size of 40 μm or less were evaluated as “◯ (good)” and those having a size of more than 40 μm were evaluated as “x (bad)”.

The strength evaluation after brazing shown in Table 3 is carried out by brazing each test material and then performing a tensile test (JISZ2).
201), with a proof stress of 130 N / mm ² or more is “good”, and when less than 130 N / mm ² is “x”.
(Poor) "was evaluated.

Further, in the corrosion resistance evaluation shown in Table 3, each test material was subjected to a CASS test (JISSH8502-1988) for 1000 hours, followed by a SWAAT test (AS).
After performing TMB117) for 1000 hours, the appearance of each test material was visually observed, and a sample in which no pitting corrosion was observed in both the CASS test and the SWAAT test was marked as “good (good)”, The one in which pitting corrosion was observed in either of the above two cases was evaluated as "x (poor)".

As shown in Table 3, Example D according to the present invention
In all of 1, D2, D4, and D5, the results of the above-described characteristic evaluations were all “◯ (good)” or “⊚ (extremely good)”.
You can see that. On the other hand, in Comparative Examples D3 and D6 to D11 which do not satisfy the requirements of the present invention, at least one of the results of the above-mentioned characteristic evaluation is “×”.
(Defective) ”. From the above results, the aluminum alloy clad material 1 having a three-layer structure according to the present invention is excellent in erosion resistance, formability (elongation, Erichsen value, etc.), strength after brazing, and corrosion resistance. It became clear.

[0043]

EFFECTS OF THE INVENTION The aluminum alloy clad material according to the present invention constructed as described above has the following excellent effects. That is, according to the first aspect of the present invention, an aluminum alloy clad material obtained by clad with a brazing material made of an Al-Si type aluminum alloy on both surfaces of a core material made of an Al-Mn type aluminum alloy. In the above, the 0.2% proof stress of the aluminum alloy clad material is set to an appropriate range based on the proof stress of the O material of the aluminum alloy clad material, and the chemical composition of the core material and the brazing material contained in the aluminum alloy clad material is determined. By setting the amount within the appropriate range, the residual processing strain, which is a driving force for promoting the recrystallization of the structure of the cladding portion, can be appropriately formed. As a result, it is possible to provide an aluminum alloy clad material for a heat exchanger that achieves both prevention of erosion and excellent formability (elongation, Erichsen value, etc.).

Furthermore, since a brazing filler metal obtained by adding Zn to an Al--Si aluminum alloy is clad on one surface of the Al--Mn-based core material, the core material is heat-treated to provide corrosion resistance by the sacrificial anode effect. An aluminum alloy clad material for a exchanger can be provided.

According to the invention of claim 2, in addition to the above-mentioned effects, it becomes possible to provide an aluminum alloy clad material for a heat exchanger having further improved formability.

[Brief description of drawings]

FIG. 1 is a drawing schematically showing a configuration of an aluminum alloy clad material according to the present invention.

[Explanation of symbols]

1 Aluminum alloy clad material (3-layer structure) 2 heartwood 3 Outside (air side) brazing material 4 Inside (refrigerant side) brazing material

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Osamu Takezoe             15 Kinugaoka, Moka City, Tochigi Prefecture God Inc.             Inside the Tooka Works Moka Works

Claims (2)

[Claims] 1. An aluminum alloy clad material in which a brazing material made of an Al—Si type aluminum alloy is clad on both surfaces of a core material made of an Al—Mn type aluminum alloy. The material has a 0.2% proof stress σ ₁ , which is defined as a load per unit cross-sectional area that causes a permanent elongation of 0.2%.
1.3 × σ ₂ ≤σ ₁ ≤2. With respect to the proof stress σ _{2 of the} material.
9 × has sigma ₂ the relationship, the core material, a Cu containing 0.05 to 0.3 wt%, and the remainder Al, Mn, and Ti and inevitable impurities Al
-Mn-based aluminum alloy, and at least one of the brazing filler metals provided on both sides of the core material contains Si in an amount of 7 to 13% by mass, Zn in an amount of 1 to 10% by mass, and the balance being Al. An aluminum alloy clad material for a heat exchanger, which is composed of an aluminum alloy that is inevitable impurities. 2. The core material further comprises Si of 0.2-1.
The aluminum alloy clad material for a heat exchanger according to claim 1, which is composed of an aluminum alloy containing 0% by mass.