JP2006281266A - Aluminum alloy clad material, its manufacturing method, and heat exchanger using the same aluminum alloy clad material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an aluminum alloy clad material suitable for manufacturing a heat exchanger, which can solve such problems that the aluminum alloy clad material for fin material is difficult to manufacture because a many kinds of alloy elements are added to increase the strength, so that coarse primary crystals of the compounds are produced and breakages are caused in the following rolling processes, and also the hanging-down resistance becomes worse when a large amount of Si is contained in a core material, and which has excellent strength and soldering property and can be easily manufactured. <P>SOLUTION: The aluminum alloy clad material is composed by cladding an Al-Si alloy solder material, which contains 6.5 to 11.0 mass% Si, on both surfaces of an aluminum alloy core material, which contains 0.005 to 0.6 mass% Si, 0.03 to 0.8 mass% Fe, 1.5 to 3.0 mass% Mn, 0.5 to 3.0 mass% Zn, and further at least one of 0.4 mass% or less Mg and 0.2 mass% Cu, if necessary. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an aluminum alloy clad material used for a fin material or the like of a heat exchanger of an automobile or the like and a manufacturing method thereof.

  A heat exchanger for an automobile such as a radiator is composed of a plurality of refrigerant tanks, a plurality of tubes installed between these tanks, and a fin material joined to each tube. It is circulated and can exchange heat efficiently through the fins. The fin material is produced by corrugating an aluminum alloy plate and brazing and joining with a tube material. In consideration of the brazing property at this time, a fin material made of a brazing sheet in which a brazing material such as an Al—Si based alloy is previously clad on an Al alloy core material is often used.

By the way, in recent years, demands for weight reduction and cost reduction of heat exchangers are increasing, and thinning of fin members and other main members is further progressing. Since it is necessary to maintain and improve the characteristics of the heat exchanger when thinning the fin material, the strength of the fin material in recent years can be increased by adding various elements and studying the manufacturing process. It is illustrated.
In order to increase the strength of such an aluminum alloy, it is effective to add, for example, Mn or Fe, and as an alloy for achieving such an increase in strength, an Al—Si—Mn—Fe-based alloy can be cited ( For example, see Patent Document 1).
Japanese Patent Laid-Open No. 10-081931

However, aluminum alloys used for conventional clad materials for fin materials have been difficult to manufacture, especially when mass-produced, due to the addition of many kinds of elements to increase the strength. . For example, if a large amount of Si is added to the core material constituting the clad material, the Al, Mn, and Si compounds crystallize coarsely as primary crystals during casting, which may cause breakage in the subsequent rolling process. There was a problem.
Further, when the core material contains a large amount of Si, there is a drawback that the drooping resistance is deteriorated.

Furthermore, it has been difficult to achieve high strength without impairing the thermal conductivity, which is an important characteristic of the heat exchanger. In general, conductivity that is easy to measure is used as an index of the thermal conductivity of the alloy. Therefore, it is desirable to improve the conductivity. (For example, if the fin conductivity is increased by 5% IACS, the heat conductivity of the heat exchanger is improved by about 1%.)
In view of these problems, the present invention provides an aluminum alloy clad material suitable for the manufacture of a heat exchanger having excellent strength and brazing without impairing electrical conductivity and drooping resistance, and a method for producing the same. It is the purpose.

The present invention has been made to achieve the above object, and has been solved by the following means. That is,
(1) An aluminum alloy clad material obtained by clad an Al—Si alloy brazing material on both surfaces of an aluminum alloy core material,
The said aluminum alloy core material is Si: 0.005-0.6 mass%, Fe: 0.03-0.8 mass%, Mn: 1.5-3.0 mass%, Zn: 0.5-3. An aluminum alloy clad material containing 0% by mass and comprising the balance Al and inevitable impurities;
(2) The aluminum alloy core material according to (1), wherein the aluminum alloy core material further contains at least one of Mg: 0.4 mass% or less and Cu: 0.2 mass% or less,
(3) The Al—Si-based alloy brazing material contains Si: 6.5 to 11.0% by mass, and is composed of the balance Al and inevitable impurities, as described in (1) or (2) Aluminum alloy clad material,
(4) A heat exchanger comprising a plurality of refrigerant tanks, a plurality of tubes installed between these tanks, and a fin material brazed to each tube. A heat exchanger characterized by using the aluminum alloy clad material according to any one of 1) to (3),
(5) A casting process in which an aluminum alloy core material and an Al—Si alloy brazing material are respectively casted, a hot rolling process in which the Al—Si alloy brazing material is rolled by hot rolling, and a combination thereof are heated. A combined hot rolling process for performing hot rolling, and a manufacturing method of an aluminum alloy clad material,
The set of aluminum alloy core materials is Si: 0.005 to 0.6 mass%, Fe: 0.03 to 0.8 mass%, Mn: 1.5 to 3.0 mass%, Zn: 0.5 ~ 3.0 mass%, balance: Al and inevitable impurities,
Furthermore, the manufacturing method of the aluminum alloy clad material characterized in that the cooling rate of the molten metal in the casting step of casting the aluminum alloy core material is 5 ° C./second or more,
(6) A casting process in which an aluminum alloy core material and an Al—Si alloy brazing material are respectively casted, a hot rolling process in which the Al—Si alloy brazing material is rolled by hot rolling, and a combination thereof are heated. A combined hot rolling process for performing hot rolling, and a manufacturing method of an aluminum alloy clad material,
The composition of the aluminum alloy core material is Si: 0.005 to 0.6 mass%, Fe: 0.03 to 0.8 mass%, Mn: 1.5 to 3.0 mass%, Zn: 0.5 ~ 3.0 mass%, balance: Al and inevitable impurities,
Furthermore, the manufacturing method of the aluminum alloy clad material characterized in that the cooling rate of the molten metal in the casting step for casting the aluminum alloy core material is 100 ° C./second or more,
(7) The aluminum according to (5) or (6), wherein the aluminum alloy core material further contains at least one of Mg: 0.4% by mass or less and Cu: 0.2% by mass or less. Production method of alloy clad material, and
(8) Any of (5) to (7), wherein the Al—Si-based alloy brazing material contains Si: 6.5 to 11.0% by mass, and the balance is Al and inevitable impurities. 2. A method for producing an aluminum alloy clad material according to item 1.

  According to the present invention, it is possible to obtain an aluminum alloy clad material having high strength, good brazing property, and excellent productivity without causing cracks during rolling. This aluminum alloy clad material is extremely excellent as a heat exchanger fin material.

A preferred embodiment of the aluminum alloy clad material of the present invention will be described in detail.
The aluminum alloy clad material of the present invention is an aluminum alloy clad material obtained by clad a brazing material of an Al-Si alloy on both surfaces of an aluminum alloy core material.
The aluminum alloy core material is Si: 0.005 to 0.6% by mass, Fe: 0.03 to 0.8% by mass, Mn: 1.5 to 3.0% by mass, Zn: 0.5 to 3%. It contains 0% by mass, further contains at least one of Mg: 0.4% by mass or less and Cu: 0.2% by mass or less, and has a composition composed of the balance Al and inevitable impurities. .
The brazing material is particularly preferably an aluminum alloy containing 6.5 to 11.0% by mass of Si.

  First, for each component element of the alloy composition of the aluminum (Al) alloy core material of the present invention, the reason for selecting the element and the reason for defining the content will be described.

  Silicon (Si) in the core material is an effective component for increasing the strength of the core material, and is also necessary for securing brazing properties. In the present invention, since the preferable content of Si in the brazing material is set as high as 6.5% by mass or more, it is not necessary to increase the amount of Si in the core material, and the amount of Si normally taken from the aluminum metal If it is 0.005 mass% or more, the minimum brazing property is ensured. When the amount of Si in the brazing material is set to be small, it is necessary to increase the amount of Si in the core material. However, if the amount of Si is too large, the electrical conductivity decreases, and in particular heat conduction as a fin material for heat exchangers Characteristics will be impaired. In addition, if the amount of Si is too large, a huge crystallized product is formed together with Al-Mn during casting, and an ingot is formed with the crystallized product intervening. Such a crystallized product is not preferable because it tends to cause material breakage in the rolling process. From the viewpoint of thermal conductivity and productivity, the Si content in the core material is set to 0.6% by mass or less. From the above viewpoint, the more preferable amount of Si is 0.05% by mass to 0.3% by mass.

  It is an effective component for increasing the strength when iron (Fe) clad material is used in the core material, but in the present invention, the necessary strength is ensured mainly by the addition of Mn, so it is necessary to increase the amount of Fe. However, the minimum strength is ensured if it is 0.03% by mass or more, which is the amount of Fe normally taken from an aluminum ingot. On the other hand, if the amount of Fe is too large, huge crystallized substances are formed together with Al and Mn at the time of casting, and the productivity is impaired. Further, when the amount of Fe is large, the brazing diffusion phenomenon that the Si diffusion from the brazing material to the core material is promoted during the brazing heating and the material is melted becomes remarkable. This is because the recrystallized grains become smaller as the amount of Fe increases, so that the number of Si diffusion paths increases. For these reasons, the upper limit of the Fe content in the core material is set to 0.8 mass% or less. From the same viewpoint, the more preferable Fe content is 0.05 to 0.4% by mass.

  The addition of manganese (Mn) in the core material is for increasing the strength of the clad material. In the clad material of the present invention, Si in the brazing material diffuses into the core material during brazing heating and reacts with Mn in the core material to form an Al-Mn-Si-based compound. Strength is secured. Therefore, it is essential to add 1.5% by mass or more of Mn to the core material. If the amount of Mn is too small, the amount of Al-Mn-Si-based compound produced will be small, and sufficient strength cannot be obtained. On the other hand, when it exceeds 3.0 mass%, casting becomes difficult and further causes cracking in the rolling process. For the above reasons, the content of Mn in the core material is 1.5 mass% to 3.0 mass%, preferably 1.6 mass% to 2.5 mass%.

  Zinc (Zn) in the core material is added for the purpose of sacrificial corrosion protection of the tube material of the heat exchanger. Generally, when a tube of a heat exchanger is corroded by a refrigerant flowing inside and a hole is generated, the function as a heat exchanger cannot be maintained. Therefore, it is necessary to add Zn to the fin material to lower the potential of the fin material and prevent corrosion of the tube. Therefore, Zn is added to the core material, and the content is preferably 0.5% by mass to 3.0% by mass. This is because the effect of sacrificial corrosion protection is insufficient when the amount added is too small. If too much is added, a further sacrificial anticorrosive effect cannot be obtained, and the melting point of the core material decreases, so that the fin material may melt during brazing heating. For these reasons, the Zn content is set to 0.5% by mass or more and 3.0% by mass or less, and more preferably 1.0% by mass to 2.5% by mass.

  Since magnesium (Mg) in the core material is an effective component for increasing the strength, it is added when further enhancement of strength is desired. As described above, Si in the brazing material diffuses to the core material side during brazing heating, but Si diffused in the core material reacts with Mg present in the core material to form an Mg—Si compound. This compound contributes to high strength. On the other hand, Mg also has a function of reducing the activity of the flux by reacting with the flux used during brazing heating, so brazing cannot be performed with a material containing a large amount of Mg. Specifically, when the Mg content exceeds 0.4% by mass, the brazing property is remarkably lowered. For the above reasons, the content of Mg in the core material is 0.4 mass% or less, preferably 0.05 mass% to 0.20 mass%.

  Copper (Cu) in the core material is an effective component for increasing the strength because it dissolves in Al and causes solid solution hardening. In the present invention, Cu is an optional additive component for strengthening the strength as with Mg. . When Cu exceeds a predetermined amount, the potential of the fin becomes noble when used as a fin material, and the sacrificial anticorrosive effect of the tube is reduced. 2 mass% or less, Furthermore, 0.05 mass%-0.10 mass% are preferable.

Subsequently, the alloy composition of the Al—Si alloy brazing material will be described.
The Al—Si-based alloy brazing material is composed of an Al alloy to which Si is added in order to ensure brazing properties, and the Si content is preferably 6.5% by mass or more and 11.0% or less. Since the brazing material Si diffuses into the core material during brazing heating, the amount of Si in the brazing material at a temperature at which the brazing material melts is lower than the amount of added Si. In particular, in the present invention, since the Si amount in the core material is set as low as 0.6% by mass or less as described above, if the amount of Si in the brazing material is too small, the Si amount at the brazing temperature is reduced. Since there is too little brazing material, the brazing performance is significantly reduced. On the other hand, when there is too much Si, melting | fusing point will fall too much and the whole fin material will fuse | melt at the time of brazing heating. For these reasons, the content of Si in the brazing material is preferably 6.5% by mass or more and 11.0% by mass or less, more preferably 7.5% by mass to 10.0% by mass.

In addition to the additive elements described above, Ni, Ti, Cr, and Zr can be further added to the core component for the purpose of increasing the strength. In addition, In and Sn can be added to reduce the potential of the fin material and increase the sacrificial anticorrosive effect.
Moreover, about a brazing filler metal component, Zn and Cu can be added in the range which does not impair favorable manufacture for the purpose of melting temperature and electric potential adjustment.

Next, the manufacturing method of the aluminum alloy clad material of this invention is demonstrated.
About the aluminum alloy core material which has the said metal composition of this invention, it can manufacture by DC casting method (Direct Chill Casting Process). When manufacturing by the normal DC casting method, when the amount of Mn of the core material is small as in the conventional case, the casting can be performed without any problem. Become. On the other hand, when the cooling rate at the time of solidification of the molten metal is increased, the generation of giant crystallized substances can be suppressed. In the core material component of the present invention, when the cooling rate is 5 ° C./second or more, it is possible to prevent the occurrence of giant crystallized products, and thus casting can be performed without any problem even if Mn is large.
Specifically, by using a thin mold having a thickness of about 100 mm, the cooling rate can be increased to about 5 to 10 ° C./second, which is effective. After casting, it is rolled to a predetermined size by hot rolling. In addition, when a continuous casting and rolling method such as a twin roll caster with a higher cooling rate is used, the cooling rate can be set to about 100 to 1000 ° C./second, the crystallization part becomes finer, and the casting is further improved. It can be performed. If the cooling rate is too low, the crystallized material becomes large as described above, and when the material is cracked in the rolling process or rolled thinly to the thickness of the fin material, the crystallized material becomes the starting point and the material is cut. Or

About a brazing material, it can manufacture without a problem by the normal DC casting method. After casting the brazing material, it is rolled into a predetermined size by hot rolling, heated in combination with the core material produced above, and subjected to combined rolling to obtain a clad material.
Furthermore, an aluminum alloy clad material of a predetermined size can be obtained by performing rolling, intermediate annealing, and final rolling. The clad rate (%) of the clad material of the present invention (thickness of brazing material on one side × 100 / thickness of material) is preferably about 5 to 20%.

A heat exchanger is assembled using the obtained aluminum alloy clad material as a fin material.
A plurality of tubes are provided in parallel with each other between a plurality of refrigerant tanks, and a clad material formed in a corrugated shape is brazed to each tube to form fins to constitute a heat exchanger.

Hereinafter, the present invention will be described in more detail based on examples, but the present invention is not limited thereto.
[Examples and Comparative Examples]
An aluminum alloy ingot having a metal component and a composition ratio (shown by mass%, the balance being Al) shown in Table 1 as a core material component was manufactured by DC casting, and faced to a thickness of 40 mm. The cooling rate during melt solidification was 10 ° C./second.
Also, an aluminum alloy ingot having the alloy composition shown in Table 2 as a brazing filler component (indicated by mass% and the balance being Al) is produced by the same casting method as the above core material (cooling rate 10 ° C./second). And hot rolled at 520 ° C. to a thickness of 5 mm.

Next, brazing materials were combined on the front and back of the core material in the combinations shown in Table 3, and hot rolled at 520 ° C. to obtain a double-sided brazing clad material. By performing rolling and intermediate annealing on this clad material, an aluminum alloy clad material for heat exchanger fin material having a final rolling rate of 30% and a final plate thickness of 0.1 mm was produced. In addition, each clad rate of front and back is 10%. Table 3 shows the rolling condition of each clad material.
The aluminum alloy clad material for a heat exchanger fin material produced as described above was heated at 600 ° C. for 5 minutes corresponding to the brazing condition, and then the strength was measured by a tensile test. For the strength, three test pieces of JIS Z2201-13B cut out from the rolling direction were measured according to JIS Z2241, and the average values are shown in Table 3.

  Further, the corrugated material processed by slitting the fin material to a width of 20 mm was combined with a JIS-A3003 alloy plate material having a width of 20 mm and a plate thickness of 0.5 mm for a tube material to assemble a minicore simulating a heat exchanger. Nocollock brazing flux was applied to the mini-core, and brazing heating was performed. Heating was performed in a nitrogen atmosphere with an oxygen concentration of 100 ppm or less, and the temperature condition was maintained at 600 ° C. for 5 minutes. Table 3 shows the result of observing the joined state of the tube material and the fin material for the brazed mini-core.

As shown in Table 3, Invention Example No. The aluminum alloy clad materials 1 to 12 could be produced without causing any particular problems in the rolling process, etc., had high strength after brazing, and had good brazing properties.
On the other hand, no. 13 and no. No. 15 had a lower strength after brazing because the amount of Si and Mn in the core material was less than the amount specified in the present invention. No. 14 and no. In No. 16, since the amount of Fe and Mn in the core material was larger than the addition amount specified in the present invention, cracks occurred during cold rolling after the combined rolling, and a material to be used for the test could not be manufactured. . No. No. 17, the amount of Mg in the core material was larger than the amount specified in the present invention, so the strength after heating corresponding to the brazing conditions of the aluminum alloy clad material was high, but in the test for assembling the mini-core, Sometimes fillets were not formed and brazing was not possible. No. In No. 18, the amount of Zn in the core material was larger than the addition amount specified in the present invention, so that the fin was melted by brazing heating.

  No. In No. 19, since the amount of Si in the brazing material was less than the amount specified in the present invention, no fillet was formed in the brazing of the mini-core, and brazing could not be performed. No. In No. 20, the amount of Si in the brazing material was larger than the amount specified in the present invention, so the fins were melted by brazing heating.

As described above, according to the present invention, an aluminum alloy clad suitable for heat exchanger fins that has high strength, good brazeability, and excellent productivity without causing cracks during rolling. A material can be obtained.

Claims (8)

An aluminum alloy clad material obtained by clad Al-Si alloy brazing material on both sides of an aluminum alloy core material,
The said aluminum alloy core material is Si: 0.005-0.6 mass%, Fe: 0.03-0.8 mass%, Mn: 1.5-3.0 mass%, Zn: 0.5-3. An aluminum alloy clad material containing 0% by mass and comprising the balance Al and inevitable impurities.   The aluminum alloy clad material according to claim 1, wherein the aluminum alloy core material further contains at least one of Mg: 0.4 mass% or less and Cu: 0.2 mass% or less.   3. The aluminum alloy clad according to claim 1, wherein the Al—Si alloy brazing material contains Si: 6.5 to 11.0 mass%, and consists of the balance Al and inevitable impurities. Wood.   A heat exchanger comprising a plurality of refrigerant tanks, a plurality of tubes installed between these tanks, and a fin material brazed to each tube, wherein the fin materials are claimed in claims 1 to 3. A heat exchanger using the aluminum alloy clad material according to claim 3. A casting process for casting an aluminum alloy core material and an Al-Si alloy brazing material, a hot rolling process for rolling the Al-Si alloy brazing material by hot rolling, and a combination of these processes to heat A combined hot rolling step for rolling, and a method for producing an aluminum alloy clad material,
The set of aluminum alloy core materials is Si: 0.005 to 0.6 mass%, Fe: 0.03 to 0.8 mass%, Mn: 1.5 to 3.0 mass%, Zn: 0.5 ~ 3.0 mass%, balance: Al and inevitable impurities,
Furthermore, the manufacturing method of the aluminum alloy clad material characterized by the molten metal cooling rate in the casting process which casts the said aluminum alloy core material being 5 degree-C / sec or more. A casting process for casting an aluminum alloy core material and an Al-Si alloy brazing material, a hot rolling process for rolling the Al-Si alloy brazing material by hot rolling, and a combination of these processes to heat A combined hot rolling step for rolling, and a method for producing an aluminum alloy clad material,
The composition of the aluminum alloy core material is Si: 0.005 to 0.6 mass%, Fe: 0.03 to 0.8 mass%, Mn: 1.5 to 3.0 mass%, Zn: 0.5 ~ 3.0 mass%, balance: Al and inevitable impurities,
Furthermore, the cooling rate of the molten metal in the casting process for casting the aluminum alloy core material is 100 ° C./second or more.   The aluminum alloy clad material according to claim 5 or 6, wherein the aluminum alloy core material further contains at least one of Mg: 0.4 mass% or less and Cu: 0.2 mass% or less. Manufacturing method. The said Al-Si type alloy brazing material contains Si: 6.5-11.0 mass%, and consists of remainder Al and an unavoidable impurity, The any one of Claims 5-7 characterized by the above-mentioned. The manufacturing method of the aluminum alloy clad material of description.