WO2019181768A1 - Aluminum alloy fin material for heat exchanger, production method therefor, and heat exchanger - Google Patents

Abstract

This aluminum alloy fin material for a heat exchanger is characterized by comprising an aluminum alloy containing 1.00-1.60 mass% of Mn, 0.70-1.20 mass% of Si, 0.05-0.50 mass% of Fe, 0.05-0.35 mass% of Cu, and 1.00-1.80 mass% of Zn, the remaining portion being Al and incidental impurities, wherein the matrix of the aluminum alloy has a fibrous structure, and the aluminum alloy fin material has a tensile strength of 170-230 MPa. The present invention can provide an aluminum alloy fin material that is for a heat exchanger and that has superior moldability before brazing, superior brazeability, and superior strength characteristics and corrosion resistance after brazing.

Description

Aluminum alloy fin material for heat exchanger, method for producing the same, and heat exchanger

The present invention relates to an aluminum alloy fin material used for manufacturing an aluminum alloy heat exchanger, a manufacturing method thereof, and a heat exchanger manufactured using the aluminum alloy fin material.

Aluminum alloy heat exchangers are widely used as heat exchangers for automobiles such as radiators, heaters, oil coolers, intercoolers, evaporators and condensers for air conditioners, and oil coolers for hydraulic equipment and industrial machinery. ing. The fin material of this aluminum alloy heat exchanger is required to have a sacrificial anode effect to corrode the tube material whose inner surface serves as a passage for the working fluid (refrigerant), and at the same time high temperature during brazing additional heat for manufacturing the core Brazing joint properties such as buckling deformation and brazing corrosion are required.

In order to satisfy such requirements, conventionally, aluminum alloy fin materials include Al-Mn-based materials such as JIS-A3003 and JIS-A3203, Al-Mn-Si meters, Al-Mn-Si-Cu meters, etc. An aluminum alloy fin material containing Mn has been used. Furthermore, in order to give the sacrificial anode effect to the fin material made of aluminum alloy, a method of adding a base such as Zn, Sn, In or the like to make it base electrochemically has been used.

In recent years, with the demand for reducing the weight of automobiles, automobile heat exchangers are also required to be made thinner from the viewpoint of energy saving and resource saving, and the fin materials are also expected to be thinner. Since thinning the fin material affects the rigidity of the heat exchanger, a fin material with excellent strength after brazing is required, and an aluminum alloy with Fe, Cu, Zn added to JIS-A3003 is proposed. Has been.

In Patent Document 1, 1.0 to 2.0% by mass of Mn, 0.5 to 1.3% by mass of Si, 0.1 to 0.8% by mass of Fe, 0.20% by mass exceeding 0. 4% by mass or less of Cu, 1.1% by mass or more and less than 2.0% by mass of Zn, the balance being aluminum alloy fin material made of Al and inevitable impurities, and the matrix of the aluminum alloy fin material has a recrystallized structure An aluminum alloy fin material for a heat exchanger is disclosed.

In Patent Document 2, Mn: 1.0% (mass%, the same applies hereinafter) to 2.0%, Si: 0.5% to 1.3%, Fe: 0.1% to 0.8% Cu: 0.21% to 0.5%, Zn: 1.1% to 5%, the content ratio of Mn and Si (Mn% / Si%) is 1.0 to 3.5, Zn and The content ratio with respect to Cu (Zn% / Cu%) is 5 to 15, and one or two of Zr: 0.05% to 0.3% and Cr: 0.05% to 0.3% An aluminum alloy fin material for a heat exchanger is disclosed that contains seeds, the balance being Al and inevitable impurities, and a tensile strength of 160 to 270 MPa.

In Patent Document 3, a) Si is 0.3 to 1.5%, Fe is ≦ 0.5%, Cu is ≦ 0.3%, Mn is 1.0 to 2.0%, Mg is ≦ 0.5%, more preferably ≦ 0.3%, Zn ≦ 4.0%, Ni ≦ 0.5%, dispersion forming elements derived from IVb, Vb, or VIb group respectively ≦ 0.3 % And unavoidable impurity elements of 0.05% or less and 0.15% or less as a whole, and a balance aluminum is cast to obtain an ingot, and b) less than 550 ° C., preferably 400 to Preheating the ingot to form dispersoid particles at a temperature of 520 ° C., more preferably 450 to 520 ° C., in particular 470 ° C. and up to 520 ° C .; c) hot rolling to obtain a strip; d) The strip obtained in step (c) Above, preferably cold rolling at> 95% to obtain a strip having a first proof stress value, and e) a second proof stress value is then obtained immediately after the cold rolling in step (d). A strip having a 10% to 50% lower, preferably 15 to 40% lower than the first proof stress value, and a 0.2% proof stress range of 100 to 200 MPa, more preferably 120 to 180 MPa, most preferably 140 to 180 MPa. In order to soften the material by tempering without recrystallizing the strip alloy in such a way that it is heat-treated to the delivery tempering, in the range of 50-400 nm in diameter in the delivery tempering. The dispersoid particle density of the particles is 1 to 20 × 10 ⁶ , preferably 1.3 to 0.5 × 10 ⁶ , most preferably 1.4 to 7 × 10 ⁶ particles / mm. A ² sagging resistant strip is disclosed.

JP 2013-40367 A JP 2002-161324 A Japanese Patent Laid-Open No. 2008-190027

Normally, fin materials for heat exchangers are corrugated and then brazed and combined with tube materials. Since the fin material joined by brazing imparts rigidity to the entire core and exerts a sacrificial anticorrosive effect on the tube material in an external corrosion environment, the bonding failure greatly affects the core strength and corrosion resistance. Although there are various factors of joint failure, factors such as variations in fin height during corrugation molding and deformation of the fin top due to erosion during brazing can be cited.

Patent Document 1 proposes an aluminum alloy in which Fe, Cu, and Zn are added to JIS-A3003 alloy as a high-strength fin material. There is a problem that the fin height is likely to vary, and that bonding failure is likely to occur when brazed and heated in combination with a tube.

Further, in Patent Document 2, it is an H1n material that is cold-rolled after intermediate annealing, and since it is split while holding the rolling oil containing rolling wear powder on the material surface, the rolling wear powder tends to accumulate on the slitter, This was a factor that reduced workability due to cleaning.

Patent Document 3 has a problem that the corrosion resistance is insufficient when used as a fin material and brazed to a tube material.

Therefore, an object of the present invention is to provide an aluminum alloy fin material for a heat exchanger that is excellent in molding processability before brazing, is excellent in brazing property, and is excellent in strength characteristics and corrosion resistance after brazing.

In order to solve the above-mentioned problems, the present inventors have examined the relationship between the brazeability, strength characteristics, sacrificial anode effect, alloy components, combinations of alloy components, material strength properties, internal structure, etc. , Si, Cu, Mn, Zn addition amount, and the matrix structure of the fin material are made appropriate to increase the strength after brazing while lowering the strength before brazing, and ensure good brazing and corrosion resistance The present invention has been completed.

That is, the present invention (1) includes 1.00 to 1.60% by mass of Mn, 0.70 to 1.20% by mass of Si, 0.05 to 0.50% by mass of Fe, It contains 05 to 0.35 mass% Cu and 1.00 to 1.80 mass% Zn, and the balance is made of an aluminum alloy composed of Al and inevitable impurities,
The matrix of the aluminum alloy is a fibrous structure;
The tensile strength is 170 to 230 MPa,
An aluminum alloy fin material for heat exchangers is provided.

Further, the present invention (2) provides the aluminum alloy fin material for a heat exchanger according to (1), wherein the aluminum alloy further contains 0.20% by mass or less of Zr.

Also, in the present invention (3), the aluminum alloy is an H2n (n is an integer selected from 2, 4 and 6) material, either (1) or (2) An aluminum alloy fin material for a heat exchanger is provided.

Further, the present invention (4) is based on the total of Al—Mn intermetallic compound and Al—Si—Mn intermetallic compound having an equivalent circle diameter of 0.1 to 1.0 μm in the brazed aluminum alloy. For the heat exchanger according to any one of (1) to (3), wherein the number density is 0.50 × 10 ⁶ pieces / mm ² or more and the crystal grain size after brazing is 40 to 200 μm. An aluminum alloy fin material is provided.

In the invention (5), 1.00 to 1.60% by mass of Mn, 0.70 to 1.20% by mass of Si, 0.05 to 0.50% by mass of Fe, An ingot made of an aluminum alloy containing 05 to 0.35% by mass of Cu and 1.00 to 1.80% by mass of Zn and the balance being made of Al and inevitable impurities is not homogenized. In addition, whether the hot rolling is started by heating to 400 to 500 ° C., the hot rolling is finished, the hot rolling is finished at 350 ° C. or less, and then the cold rolling is performed in one or more passes. Alternatively, the aluminum alloy fin material for heat exchangers is characterized in that one or more passes of cold rolling and one or more intermediate annealings performed between cold rolling passes and then final annealing are performed. The manufacturing method of this is provided.

The present invention (6) is a heat exchanger obtained by brazing the aluminum alloy fin material for a heat exchanger according to any one of (1) to (5),
The crystal grain size of the aluminum alloy constituting the fins of the heat exchanger is 40 to 200 μm, and the Al—Mn intermetallic compound and Al—Si having an equivalent circle diameter of 0.1 to 1.0 μm in the aluminum alloy The total number density of the Mn-based intermetallic compounds is 0.50 × 10 ⁶ pieces / mm ² or more,
The heat exchanger characterized by this is provided.

According to the present invention, it is possible to provide an aluminum alloy fin material for a heat exchanger that is excellent in moldability before brazing, excellent in brazing, strength characteristics after brazing, and excellent in corrosion resistance.

The aluminum alloy fin material for a heat exchanger of the present invention comprises 1.00 to 1.60% by mass of Mn, 0.70 to 1.20% by mass of Si, 0.05 to 0.50% by mass of Fe, 0.05 to 0.35 mass% Cu and 1.00 to 1.80 mass% Zn, the balance being made of an aluminum alloy composed of Al and inevitable impurities,
The matrix of the aluminum alloy is a fibrous structure;
The tensile strength is 170 to 230 MPa,
This is an aluminum alloy fin material for heat exchangers.

The aluminum alloy fin material for heat exchanger of the present invention is made of an aluminum alloy. That is, the aluminum alloy fin material for heat exchanger of the present invention is made of an aluminum alloy.

The aluminum alloy according to the aluminum alloy fin material for heat exchanger of the present invention contains Mn. Mn coexists with Si to produce an Al—Si—Mn intermetallic compound, which increases the strength of the fin material before and after brazing, as well as high temperature buckling resistance and moldability. Make good. The Mn content in the aluminum alloy is 1.00 to 1.60% by mass. When the content of Mn in the aluminum alloy is in the above range, the strength of the fin material before brazing and after brazing is increased, and high temperature buckling resistance and moldability are improved. On the other hand, if the content of Mn in the aluminum alloy is less than the above range, the effect of Mn becomes too small, and if it exceeds the above range, the strength before brazing becomes too high, and the formability becomes low. At the same time, a coarse crystallized product is produced at the time of casting, and the rolling processability is impaired. As a result, it is difficult to obtain a sound plate material.

The aluminum alloy according to the aluminum alloy fin material for heat exchanger of the present invention contains Si. Si is expected to produce an Al—Si—Mn intermetallic compound by coexisting with Mn and increase the strength of the fin material before and after brazing. The Si content in the aluminum alloy is 0.70 to 1.20% by mass. When the Si content in the aluminum alloy is in the above range, the strength of the fin material before brazing and after brazing is increased. On the other hand, if the Si content in the aluminum alloy is less than the above range, the effect of Si is too small. If it exceeds the above range, the melting point is lowered and local melting is likely to occur during brazing.

The aluminum alloy according to the aluminum alloy fin material for heat exchanger of the present invention contains Fe. Fe improves the strength of the fin material before and after brazing and improves the moldability. The Fe content in the aluminum alloy is 0.05 to 0.50 mass%. When the content of Fe in the aluminum alloy is in the above range, the strength of the fin material before brazing and after brazing is increased and the moldability is improved. On the other hand, if the Fe content in the aluminum alloy is less than the above range, the effect of Fe becomes too small, and if it exceeds the above range, it becomes a cathode for the aluminum base material and the corrosion resistance is low.

The aluminum alloy according to the aluminum alloy fin material for heat exchanger of the present invention contains Cu. Cu increases the strength of the fin material before and after brazing and improves the moldability. The Cu content in the aluminum alloy is 0.05 to 0.35 mass%. When the content of Cu in the aluminum alloy is in the above range, the strength of the fin material before brazing and after brazing is increased and the moldability is improved. On the other hand, if the Cu content in the aluminum alloy is less than the above range, the effect of Cu becomes too small, and if it exceeds the above range, the potential of the fin material becomes noble, the sacrificial anode effect becomes low, and the melting point Becomes low and local melting tends to occur during brazing.

The aluminum alloy according to the aluminum alloy fin material for heat exchanger of the present invention contains Zn. Zn lowers the potential of the fin material and imparts a sacrificial anode effect to the tube material. The Zn content in the aluminum alloy is 1.00 to 1.80 mass%. When the Zn content in the aluminum alloy is in the above range, the sacrificial anode effect on the tube material is increased. On the other hand, if the Zn content in the aluminum alloy is less than the above range, the effect of Zn becomes too small, and if it exceeds the above range, the intergranular corrosion sensitivity becomes high and the melting point becomes low. Sometimes local melting tends to occur.

The aluminum alloy according to the aluminum alloy fin material for a heat exchanger of the present invention may further contain 0.20% by mass or less of Zr as necessary. Zr increases the strength of the fin material before and after brazing, coarsens the crystal grain size after brazing, and increases the high temperature buckling resistance and brazing properties. When Zr in the aluminum alloy is in the above range, the strength of the fin material before brazing and after brazing is increased, and high-temperature buckling resistance and brazing performance are increased. When the content of Zr in the aluminum alloy exceeds the above range, coarse crystallized products are generated during casting, making it difficult to produce a sound plate material.

The aluminum alloy matrix according to the aluminum alloy fin material for heat exchanger of the present invention has a fibrous structure. Since the matrix of the aluminum alloy has a fibrous structure, the elongation before brazing becomes good and the moldability becomes high. When the matrix of the aluminum alloy has a recrystallized structure, the elongation before brazing becomes small and the formability becomes low.

The tensile strength (tensile strength before brazing) of the aluminum alloy fin material for heat exchanger of the present invention is 170 to 230 MPa. If the tensile strength of the aluminum alloy fin material before brazing is less than the above range, it will be difficult to maintain the shape after molding, and if it exceeds the above range, the springback during molding will increase and the aim will be It becomes difficult to make the shape.

The aluminum alloy according to the aluminum alloy fin material for heat exchanger of the present invention is an H2n (n is an integer selected from 2, 4 and 6) material.

In the aluminum alloy fin material for a heat exchanger of the present invention, the crystal grain size after brazing is set to 40 by setting the matrix of the aluminum alloy to a fibrous structure and setting the composition of the chemical component in the aluminum alloy within the above range. It can be controlled to ˜200 μm. Then, the crystal grain size of the aluminum alloy after brazing is 40 to 200 μm, preferably 40 to 100 μm, so that the brazing property is increased and the strength is enhanced while suppressing the occurrence of erosion. The brazing heating conditions for brazing are normal brazing heating conditions at 580 to 610 ° C. for 1 to 10 minutes.

Moreover, in the aluminum alloy fin material for heat exchangers of the present invention, the content of Si and Mn in the aluminum alloy is set in the above range, and an appropriate heat treatment described below is applied, whereby 0% in the aluminum alloy after brazing heating is added. The total number density of the Al—Mn intermetallic compound and the Al—Si—Mn intermetallic compound having an equivalent circle diameter of 1 to 1.0 μm is 0.50 × 10 ⁶ pieces / mm ² or more, preferably It can be controlled to 0.60 × 10 ⁶ pieces / mm ² or more. The aluminum alloy fin material for a heat exchanger of the present invention contains Si and Mn specified in appropriate amounts, and is subjected to an appropriate heat treatment described below, whereby 0.1 to 1.0 μm circle is added to the matrix. Al—Mn-based intermetallic compounds and Al—Si—Mn-based intermetallic compounds having equivalent diameters are precipitated and contribute to increasing the strength of the fin material by the pinning effect of processing strain. The total number density of the Al—Mn intermetallic compound and Al—Si—Mn intermetallic compound having an equivalent circle diameter of 0.1 to 1.0 μm in the aluminum alloy after brazing is 0.50 × 10 ⁶ pieces / mm ² or more, preferably 0.60 × 10 ⁶ pieces / mm ² or more. When the equivalent circle diameter of the intermetallic compound to be deposited is less than the above range, the pinning effect is small, and even if the above range is exceeded, the pinning effect is small. Moreover, when the number density of the intermetallic compound to precipitate is less than the said range, intensity | strength will become low.

Moreover, in the aluminum alloy fin material for heat exchangers of the present invention, the aluminum alloy matrix has a fibrous structure, the composition of the chemical components in the aluminum alloy is within the above range, and an appropriate heat treatment described below is applied. In addition to controlling the crystal grain size after brazing to 40 to 200 μm, the content of Si and Mn in the aluminum alloy is set in the above range, and an appropriate heat treatment as described below is applied, so that The total number density of the Al—Mn intermetallic compound and the Al—Si—Mn intermetallic compound having an equivalent circle diameter of 0.1 to 1.0 μm in the aluminum alloy is 0.50 × 10 ⁶ pieces / mm. ² or more, preferably by a 0.60 × 10 ⁶ cells / mm ² or more, it is possible to increase the strength after brazing.

In the aluminum alloy fin material for heat exchanger of the present invention, the tensile strength of the aluminum alloy after brazing is 150 to 180 MPa.

Moreover, in the aluminum alloy fin material for heat exchangers of the present invention, the self-corrosion resistance of the fin is increased by setting the Zn content in the aluminum alloy to 1.00 to 1.80 mass%.

The method for producing an aluminum alloy fin material for a heat exchanger according to the present invention comprises 1.00 to 1.60% by mass of Mn, 0.70 to 1.20% by mass of Si, and 0.05 to 0.50% by mass. In an ingot made of an aluminum alloy containing 0.05 to 0.35 mass% Cu and 1.00 to 1.80 mass% Zn, with the balance being Al and inevitable impurities. Without homogenization, heat to 400 to 500 ° C. to start hot rolling to perform hot rolling, finish hot rolling at 350 ° C. or lower, and then perform one or more passes. A heat characterized by performing cold rolling, or performing one or more passes of cold rolling and one or more intermediate annealings between cold rolling passes, followed by final annealing. It is a manufacturing method of the aluminum alloy fin material for exchangers.

In the method for producing an aluminum alloy fin material for a heat exchanger according to the present invention, an ingot of an aluminum alloy having a predetermined chemical composition is cast according to a conventional method, and the ingot is subjected to hot rolling without homogenization treatment. One or more passes of cold rolling or one or more passes of cold rolling and one or more intermediate annealings and final annealings, and a predetermined thickness. An aluminum alloy fin material for a heat exchanger is obtained. In hot rolling, hot rolling is started at 400 to 500 ° C., hot rolling is performed, and hot rolling is ended at 350 ° C. or less. After hot rolling, perform one or more passes of cold rolling, or one or more passes between cold rolling and cold rolling passes one or more times Intermediate annealing is performed, and then final annealing is performed to obtain an aluminum alloy fin material for a heat exchanger. At this time, the matrix of the aluminum alloy which comprises a fin material can be made into a fibrous structure by selecting suitably the workability in cold working, annealing temperature, annealing time, and the cooling rate after annealing. However, in order to make the aluminum alloy matrix into a fibrous structure, the final annealing temperature needs to be lower than the recrystallization start temperature of the aluminum alloy after the cold rolling subsequent to the hot rolling. The recrystallization start temperature of the aluminum alloy varies depending on the components of the aluminum alloy, the hot rolling start temperature and the hot rolling end temperature, and the degree of work in cold rolling after hot rolling, so the final annealing temperature is set accordingly. .

Although it is discrimination | determination of the structure | tissue of aluminum alloy, it can discriminate | determine whether it is a recrystallized structure | tissue or a fibrous structure | tissue by performing grinding | polishing and the etching process which can observe a crystal grain boundary, and observing with an optical microscope. When the grain boundary can be clearly observed and the rolled structure whose structure is extended to a fiber is not observed, it is a recrystallized structure. On the other hand, when the grain boundary is not clearly observed and the rolled structure is observed Is identified as a fibrous tissue. There are cases where recrystallized structure and fibrous structure are mixed, but when recrystallized structure and fibrous structure are mixed, the crystal grain size after brazing partially increases, resulting in large variations in mechanical properties. It is not preferable.

The heat exchanger of the present invention is a heat exchanger obtained by brazing the aluminum alloy fin material for heat exchanger of the present invention,
The crystal grain size of the aluminum alloy constituting the fins of the heat exchanger is 40 to 200 μm, and the Al—Mn intermetallic compound and Al—Si having an equivalent circle diameter of 0.1 to 1.0 μm in the aluminum alloy The total number density of the Mn-based intermetallic compounds is 0.50 × 10 ⁶ pieces / mm ² or more,
It is a heat exchanger characterized by this.

The heat exchanger of the present invention is formed by forming the aluminum alloy fin material for a heat exchanger of the present invention into the shape of a fin constituting the heat exchanger and combining with other members constituting the heat exchanger such as a tube material or a plate material. It is manufactured by brazing and joining. That is, the heat exchanger of the present invention is a fin obtained by brazing and heating the aluminum alloy fin material for heat exchanger of the present invention, and a member constituting another heat exchanger such as a tube material and a plate material, Have

Since the fin material according to the heat exchanger of the present invention is obtained by brazing and heating the aluminum alloy fin material for heat exchanger of the present invention, Mn of 1.00 to 1.60 mass% and 0.70 to 1. 20% by mass of Si, 0.05 to 0.50% by mass of Fe, 0.05 to 0.35% by mass of Cu, and 1.00 to 1.80% by mass of Zn, The balance is made of an aluminum alloy composed of Al and inevitable impurities.

The fin according to the heat exchanger of the present invention has high strength because the aluminum alloy fin material for heat exchanger of the present invention is brazed and heated. The tensile strength of the fin according to the heat exchanger of the present invention is 150 to 180 MPa.

As the tube material, a two-layer material composed of a brazing material and a core material on the outer surface side, or a three- to four-layer material in which a brazing material or a sacrificial material is arranged on the inner surface side, is formed into a tube shape, In these tubes of 2 to 4 layers, an inner fin made of corrugated bare fin or clad fin is arranged to form a brazing strip, and the side end face is welded to form a circular tube, and flattened by roll forming. A tube-shaped one is used. In addition, as a tube material, a flat tube shape can be formed by brazing heating without overlapping by overlapping a part of the end side of the plate or by bending a part of the plate so as to become an inner column of the tube. Also used.

Also, brazing filler metal powder such as Si powder can be coated on the outer surface of the extruded flat multi-hole tube and brazed to the fin material. The brazing material powder can be mixed with a powder having a flux component, a powder having a sacrificial anode effect, and a binder. As the plate material, a plate in which a brazing material and a sacrificial anode material are clad as necessary is used as a core material. It is used after being molded into a desired shape.

The core material of the brazing sheet used as the tube material is not particularly limited as long as it is used for a heat exchanger, but is pure Al, Al—Cu alloy, Al—Mn alloy, Al—Mn. -Cu-based alloy, Al-Cu-Mn-Mg-based alloy and the like.

As the brazing filler metal component, any alloy may be used as long as it has a melting point lower than that of the tube material or the plate material. For example, Al—Si alloy, Al—Si—Zn alloy, Al— Examples thereof include an aluminum alloy powder containing Si such as a Si—Cu alloy, a flux that contains Si such as K ₂ SiF ₆ and generates a brazing material during brazing.

Brazing heating conditions at the time of brazing are not particularly limited as long as they are conditions used in ordinary brazing heating, but are, for example, normal brazing heating conditions at 580 to 610 ° C. for 1 to 10 minutes. The cooling rate after brazing is preferably 50 to 80 ° C./min from 550 ° C. to 450 ° C. If it is too slow, Cu-based precipitates are likely to precipitate along the grain boundaries, and intergranular corrosion tends to occur.

In the heat exchanger of the present invention, the crystal grain size of the aluminum alloy constituting the fin is 40 to 200 μm, preferably 40 to 100 μm. When the crystal grain size of the aluminum alloy constituting the fin is in the above range, the strength of the fin is increased.

In the heat exchanger of the present invention, the total number of Al—Mn-based intermetallic compounds and Al—Si—Mn-based intermetallic compounds having an equivalent circle diameter of 0.1 to 1.0 μm in the aluminum alloy constituting the fins. The density is 0.50 × 10 ⁶ pieces / mm ² or more, preferably 0.60 × 10 ⁶ pieces / mm ² or more. The total number density of the Al—Mn-based intermetallic compound having an equivalent circle diameter of 0.1 to 1.0 μm and the Al—Si—Mn-based intermetallic compound in the aluminum alloy constituting the fin is in the above range. , The strength of the fin is increased. The upper limit of the total number density of the Al—Mn-based intermetallic compound and the Al—Si—Mn-based intermetallic compound having an equivalent circle diameter of 0.1 to 1.0 μm in the aluminum alloy constituting the fin is preferably 8.00 × 10 ⁶ pieces / mm ² or less, more preferably 5.00 × 10 ⁶ pieces / mm ² or less, and particularly preferably 3.00 × 10 ⁶ pieces / mm ² or less.

Since the fins in the heat exchanger of the present invention are obtained by brazing and heating the aluminum alloy fin material for heat exchangers of the present invention, the heat exchanger of the present invention has fins of 1.00 to 1.60% by mass. Mn, 0.70 to 1.20 mass% Si, 0.05 to 0.50 mass% Fe, 0.05 to 0.35 mass% Cu, and 1.00 to 1.80 Containing, by mass, Zn, the balance being an aluminum alloy consisting of Al and inevitable impurities,
Al—Mn-based intermetallic compound and Al—Si— having a crystal grain size of 40 to 200 μm in the fin and having an equivalent circle diameter of 0.1 to 1.0 μm in the aluminum alloy constituting the fin The total number density of the Mn-based intermetallic compounds is 0.50 × 10 ⁶ pieces / mm ² or more,
It is a heat exchanger characterized by this.

Hereinafter, the present invention will be specifically described with reference to examples. However, the present invention is not limited to the examples described below.

Ingots having the compositions shown in Tables 1 and 2 were cast by continuous casting. A homogenization treatment was not performed on these alloys, and a plate (H2n material) having a thickness of 0.05 mm was manufactured through hot rolling, cold rolling, and final annealing. At this time, the structure of the aluminum alloy fin material was adjusted by adjusting the final annealing temperature. Moreover, after cold-rolling the plate | board material hot-rolled by the same method and carrying out intermediate annealing above the recrystallization completion temperature, thickness 0.05mm (H14 material) was also produced as a comparative material through finish cold rolling. .
About the aluminum alloy fin material obtained by the above, (1) structure | tissue, (2) tensile strength, and breaking elongation were evaluated in accordance with the following method. In addition, the aluminum alloy fin material obtained as described above was heated to 600 ° C. in nitrogen gas as brazing equivalent heating, and then cooled from 550 ° C. to 450 ° C. at a cooling rate of 60 ° C./min. About the obtained test piece, (3) Tensile strength after brazing equivalent heating, (4) Crystal grain size, (5) Precipitation density of intermetallic compound, (6) Corrosion resistance was evaluated. Moreover, (7) brazing property was evaluated about the aluminum alloy fin material obtained by the above.

(1) Organizational state The surface of the H2n material was polished and then etched, and the microstructure was observed by observing the microstructure with a microscope. When crystal grains could be discriminated, it was determined as a recrystallized structure, and when crystal grains were not clearly observed and a rolled structure was observed, it was determined as a fibrous structure.

(2) Tensile strength and elongation at break After molding a JIS No. 5 test piece, a tensile test was performed at room temperature to measure the tensile strength. Moreover, the test piece after a fracture | rupture was faced | matched and elongation at break was measured.

(3) Tensile strength after brazing equivalent heating The plate material after brazing equivalent heating was subjected to a tensile test to measure the tensile strength.

(4) Crystal grain size The surface after brazing equivalent heating was polished and etched, and the microstructure was observed by observing the microstructure with a microscope, and the crystal grain size was measured by a comparative method.

(5) Precipitation density of intermetallic compound The plate material after the brazing equivalent heating is cut out so that the L-ST section can be seen, a smooth surface is produced by polishing and ion milling, and an acceleration voltage of 1 kV is obtained by FE-SEM. The cross section was observed. The obtained photographic data was subjected to image analysis, and the equivalent circle diameter and the number of each particle were measured.

(6) Corrosion resistance The plate material after the above brazing equivalent heating was subjected to a corrosion test in accordance with ASTM G85-A3 SWAAT for 24 hours. The weight reduction amount and corrosion form of the fin material after the test were evaluated. The case where the self-corrosion of the fin was small and the intergranular corrosion did not occur or was slight was evaluated as ◯, and the case where the self-corrosion of the fin was large or the intergranular corrosion was remarkable was evaluated as x.

(7) Brazing property A 0.23 mm thick plate material (hereinafter referred to as tube material) is formed by corrugating a fin material, JIS-A3003 alloy as a core material, and JIS-A4045 alloy as a brazing material. Is attached to the fin top, and a 3% concentration fluoride-based flux is applied to the brazing material side surface of the tube material, followed by brazing heating at 600 ° C. for 3 minutes in a nitrogen gas atmosphere. Was made. About this minicore, the joint part of a fin material and a tube material was observed visually, and the brazing property was evaluated from the presence or absence of the buckling of a fin and fusion | melting. The case where there was neither buckling nor melting was rated as ◯, and the case where there was buckling or melting was rated as x.

As shown in Table 3, No. 1 satisfying the provisions of the present invention. 1 to No. All 3 were H2n materials, and had a tensile strength of 170 to 230 MPa and an elongation of 3% or more. Even when heated at 600 ° C., the crystal grain size was 40 μm or more, no fin melting or buckling was observed, and the brazing property was good. In addition, the number density of the intermetallic compound having an equivalent circle diameter of 0.1 to 1.0 μm after brazing is 0.50 × 10 ⁶ pieces / mm ² or more and the tensile strength is 150 MPa or more. Intensity was shown. In terms of corrosion resistance, SWAAT tests showed that both intergranular corrosion and self-corrosion were minor.

On the other hand, No. Since 4 and 5 have too high Zn content, the melting point is lowered and erosion occurs at the time of brazing, so that it cannot be said that the brazing property is good, and the self-corrosion resistance is not sufficient. No. Since materials 6 to 8 have a recrystallized structure, the elongation is small and not sufficient. No. No. 8 has a large crystal grain size after brazing, and the tensile strength after brazing is not sufficient.

Claims (6)

1.00 to 1.60 mass% Mn, 0.70 to 1.20 mass% Si, 0.05 to 0.50 mass% Fe, and 0.05 to 0.35 mass% Cu And 1.00 to 1.80 mass% Zn, and the balance is made of an aluminum alloy consisting of Al and inevitable impurities,
The matrix of the aluminum alloy is a fibrous structure;
The tensile strength is 170 to 230 MPa,
An aluminum alloy fin material for heat exchangers. The aluminum alloy fin material for a heat exchanger according to claim 1, wherein the aluminum alloy further contains 0.20 mass% or less of Zr. The aluminum alloy fin material for a heat exchanger according to claim 1 or 2, wherein the aluminum alloy is an H2n (n is an integer selected from 2, 4 and 6) material. In the aluminum alloy after brazing, the total number density of Al—Mn intermetallic compound and Al—Si—Mn intermetallic compound having an equivalent circle diameter of 0.1 to 1.0 μm is 0.50 × 10 ⁶ The aluminum alloy fin material for a heat exchanger according to any one of claims 1 to 3, wherein the number of particles / mm ² or more and the crystal grain size after brazing is 40 to 200 µm. 1.00 to 1.60 mass% Mn, 0.70 to 1.20 mass% Si, 0.05 to 0.50 mass% Fe, and 0.05 to 0.35 mass% Cu And an ingot made of an aluminum alloy containing 1.00 to 1.80% by mass of Zn and the balance being Al and inevitable impurities, heated to 400 to 500 ° C. without homogenization treatment. Start hot rolling and perform hot rolling, finish hot rolling at 350 ° C. or lower, and then perform cold rolling in one or more passes, or one or more times A method for producing an aluminum alloy fin material for a heat exchanger, comprising performing cold rolling of passes and one or more intermediate annealings performed between cold rolling passes, and then performing final annealing. A heat exchanger obtained by brazing the aluminum alloy fin material for a heat exchanger according to any one of claims 1 to 5,
The crystal grain size of the aluminum alloy constituting the fins of the heat exchanger is 40 to 200 μm, and the Al—Mn intermetallic compound and Al—Si having an equivalent circle diameter of 0.1 to 1.0 μm in the aluminum alloy A heat exchanger characterized in that the total number density of Mn-based intermetallic compounds is 0.50 × 10 ⁶ pieces / mm ² or more.