JP5830451B2 - Aluminum alloy fin material for heat exchanger for combination press - Google Patents

Description

The present invention relates to a heat exchanger use aluminum alloy fin material for combination press used for heat exchangers.

  In recent years, aluminum alloy fin materials for heat exchangers used in heat exchangers such as air conditioners (hereinafter referred to as fin materials as appropriate) have also been switched to new refrigerants in line with chlorofluorocarbon regulations, and the air conditioners themselves have become more compact and lightweight. As a result of the increase in performance and performance, the thickness has been further reduced, and the thickness has been reduced to 0.15 mm or less, and recently to about 0.09 mm.

  Here, the fin material forming method includes a draw method, a drawless method, and a combined draw / drawless method (combination method). The draw method consists of an overhanging process, a drawing process, a punching (piercing) and hole expanding process (burring), and a flaring process. Is mainly composed of an overhanging process, a drawing process, a punching and hole expanding process, an ironing process, and a flaring process.

  At the beginning of the development of the fin material in the 1970s, a draw method was adopted among the above three forming methods, and a soft aluminum alloy having excellent stretch formability was used. Thereafter, in order to cope with the trend of thinning and strengthening, the adoption of the drawless method increased, and hard aluminum alloys containing Mn began to be used for reducing seizure during ironing. After that, due to environmental issues, the abolition of organic solvent cleaning of press oil was considered, and the use of volatile presses that do not require cleaning increased, and the use of pre-coated fin materials expanded. A system (combination system) has been adopted, and various aluminum alloys having excellent strength and formability are being developed even if they are thin.

  In any of these forming methods, piercing & burring forming and reflaring forming for forming a tube hole collar in a copper tube are indispensable forming steps for the fin material. However, these moldings are severe molding for the fin material whose thickness is reduced to 0.15 mm or less. Therefore, fin materials with improved workability have been developed in response to such thinning.

  For example, in Patent Document 1, the plate thickness is 0.15 mm or less, and the grain size of the intermetallic compound, the maximum length of the large tilt grain, the average grain size of the subcrystal grains in the large tilt grain, and the like are predetermined. A defined aluminum alloy fin material having excellent formability is disclosed. Patent Document 2 discloses that the plate thickness is less than 0.11 mm, contains a predetermined amount of Fe and Ti, regulates Si and Cu to be equal to or less than a predetermined amount, and prescribes a predetermined elongation rate. An aluminum alloy fin material for heat exchangers having excellent stackability is disclosed. Patent Document 3 discloses an aluminum alloy fin material for a heat exchanger that has a plate thickness of less than 0.11 mm and that has a predetermined element content and is excellent in anti-Abek resistance. Patent Document 4 discloses a high-strength aluminum alloy thin plate for drawless fins having a plate thickness after cold rolling of 0.115 mm and a predetermined element being specified, and a method for manufacturing the same.

JP 2006-104488 A Japanese Patent No. 4275560 JP 2005-126799 A JP-A 64-8240

However, the conventional fin material has the following problems.
Although the above-described conventional techniques have improved the workability, in recent years, in addition to further miniaturization, weight reduction, and high performance of heat exchangers, fin materials that are easier to process have been supplied. Since it is expected, further improvement in workability is required. In addition, as the thickness of the material is reduced, the fin material is likely to be deformed during handling, and hence improvement in handling properties is also demanded.

Further, cracks often referred to as color cracks may occur during molding. That is, a fine crack is generated on the processed end face during the piercing and burring process, and this causes a color crack during the final reflare molding. When such a color crack occurs, when the copper tube is expanded through the color hole of the fin-molded molded product, the so-called Abek phenomenon that the interval between the laminated fins becomes extremely narrow is caused. It tends to occur. And there exists a problem that the ventilation resistance of a heat exchanger increases by this Abeck phenomenon. That is, the color crack not only impairs the appearance of the fins, but also causes problems such as a decrease in performance as a heat exchanger, thereby reducing the value as a product. Therefore, development of a fin material that can further suppress the occurrence of such color cracks is required.
Here, the fin material described in Patent Document 1 aims to improve color cracking resistance. However, since Mn is positively added, depending on the Mn content and production conditions, there is a problem that it becomes easy to work and harden by a coarse intermetallic compound or solid solution Mn. Therefore, there is room for improvement in resistance to color cracking.

  The present invention has been made in view of the above problems, and is excellent in color cracking resistance and handling properties capable of suppressing the occurrence of color cracking during molding processing for a fin material for a combination press. It is an object to provide an aluminum alloy fin material for a heat exchanger for a combination press.

That is, the aluminum alloy fin material for a heat exchanger for a combination press according to the present invention contains Fe: 0.010 to 0.4 mass%, Cu: 0.005 to 0.01 mass%, with the balance being Al and inevitable. Aluminum alloy fin material for a heat exchanger for combination press, which is made of an aluminum alloy having an Al purity of 99.30% by mass or more, and the thickness of the aluminum alloy fin material for the heat exchanger for combination press is 0. The average grain size of the sub-crystal grains is 2.5 μm or less, and the 0.2% proof stress is more than 130 MPa and 155 MPa or less.

According to such a configuration, by adding a predetermined amount of Fe, an Al—Fe-based intermetallic compound is formed, or a solid solution is formed in the aluminum matrix, and the sub-crystal grains at the time of press forming are refined. This suppresses work hardening. In addition, by adding a predetermined amount of Cu, handling properties when thinned are ensured. Moreover, the increase in an intermetallic compound is suppressed by prescribing Al purity. And by making the average grain size of subcrystal grains 2.5 μm or less, the elongation of the fin material having a thickness of less than 0.115 mm increases. Moreover, the fall of the handleability accompanying thinning is suppressed by making 0.2% yield strength more than 130 MPa and 155 MPa or less.

The aluminum alloy fin material for a heat exchanger for a combination press according to the present invention has Si: less than 0.20 mass%, Mn: less than 0.015 mass%, and Cr: 0.015 mass% or less with respect to the chemical components of the aluminum alloy. It is characterized by being.

  According to such a structure, coarsening of a crystallized substance (namely, intermetallic compound) is suppressed by suppressing Si, Mn, and Cr to below predetermined amount or less than predetermined amount.

The aluminum alloy fin material for a heat exchanger for a combination press according to the present invention is characterized by further containing Ti: 0.01 to 0.05% by mass with respect to the chemical component of the aluminum alloy.
According to such a configuration, the ingot structure is refined by adding a predetermined amount of Ti.

The aluminum alloy fin material for a heat exchanger for a combination press according to the present invention has one or more of a chemical conversion film, a corrosion-resistant resin film, a hydrophilic resin film, a hydrophilic inorganic film, and a lubricating resin film on the surface of the fin material. It may be provided .
According to the configuration like this, the corrosion resistance and hydrophilicity, moldability, it is possible to improve the characteristics according to the use environment and application or the like.

  The aluminum alloy fin material for a heat exchanger for a combination press according to the present invention can suppress color cracking when formed and improve handling properties. Therefore, it is possible to prevent problems such as deterioration of the appearance of the fins and a decrease in performance as a heat exchanger.

It is (a) perspective view and (b) side view for demonstrating the evaluation method of handling property.

Hereinafter, the form for implement | achieving the manufacturing method of the aluminum alloy fin material (henceforth a fin material suitably) for heat exchangers for combination presses concerning this invention and a fin material is demonstrated.

<Fin material>
The fin material according to the present invention is for a combination press containing a predetermined amount of Fe and Cu, the balance being made of Al and inevitable impurities, and an aluminum alloy having an Al purity of 99.30% by mass or more. And the plate | board thickness of this fin material is less than 0.115mm, the average particle diameter of a subcrystal grain is prescribed | regulated to 2.5 micrometers or less, and the proof stress exceeds 130 MPa and is 155 MPa or less. Moreover, among the inevitable impurities contained in the aluminum alloy, it is preferable to suppress Si, Mn, and Cr to a predetermined amount or less or less than a predetermined amount. Furthermore, you may contain predetermined amount of Ti as needed.
Hereinafter, for each configuration, first, the chemical components will be described, and then other configurations will be described.

(Fe: 0.010 to 0.4% by mass)
Fe is an element that contributes to suppression of work hardening because it can form an Al-Fe intermetallic compound (or solid solution in an aluminum matrix) and make the sub-crystal grains fine during press molding. There is an effect of reducing defective color cracking. Moreover, it has the effect which contributes to the magnitude | size of the subcrystal grain of an aluminum alloy plate, and the effect which improves intensity | strength. When the Fe content is less than 0.010% by mass, the above-described effects cannot be obtained, and the color cracking resistance is inferior due to press molding, and the proof stress is too low and the handling property is inferior. On the other hand, when it exceeds 0.4 mass%, a coarse intermetallic compound is formed and the color cracking resistance is inferior. Therefore, the Fe content is set to 0.010 to 0.4 mass%.

(Cu: 0.005 to 0.05 mass%)
In order to ensure the handleability when thinned, Cu is further added. The effect is acquired by addition of 0.005 mass% or more. On the other hand, when Cu content exceeds 0.05 mass%, work hardening will be caused and the Abek resistance will be reduced, and also color cracking resistance and corrosion resistance will be reduced. Therefore, Cu content shall be 0.005-0.05 mass%. More preferably, it is 0.01-0.05 mass%.

(Si: less than 0.20 mass% (including 0 mass%))
Si is an element mixed as an unavoidable impurity. However, when the Si content is 0.20% by mass or more, the crystallized product (intermetallic compound) becomes coarse, which becomes a stress concentration point at the time of forming and cracks. Is the starting point. Therefore, when Si is contained, the Si content is suppressed to less than 0.20% by mass, preferably 0.17% by mass or less. In addition, you may suppress to 0 mass%.

(Mn: less than 0.015% by mass (including 0% by mass))
Mn is an element mixed as an unavoidable impurity. However, when the Mn content is 0.015% by mass or more, the crystallized product (intermetallic compound) becomes coarse, which becomes a stress concentration point at the time of forming, and cracks. Is the starting point. Therefore, when it contains Mn, Mn content is suppressed to less than 0.015 mass%. Furthermore, it is preferable to suppress to less than 0.010 mass%, and it is more preferable to suppress to less than 0.005 mass%. In addition, you may suppress to 0 mass%.

(Cr: 0.015 mass% or less (including 0 mass%))
Cr is an element mixed as an unavoidable impurity. However, if the Cr content exceeds 0.015% by mass, the crystallized product (intermetallic compound) becomes coarse, which becomes a stress concentration point at the time of forming and cracks. Is the starting point. Therefore, when it contains Cr, Cr content is suppressed to 0.015 mass% or less. In addition, you may suppress to 0 mass%.

(Ti: 0.01-0.05 mass%)
Ti may be added as an Al—Ti—B intermediate alloy in order to refine the ingot structure. That is, an Al-Ti-B ingot refining agent having a ratio of Ti: B = 5: 1 or 5: 0.2 is melted in the form of a waffle or a rod (melting furnace, inclusion filter before slab solidification). The molten metal at any stage introduced into the degassing device and the molten metal flow rate control device may be added, and the Ti content is allowed to be 0.05 mass%. If the Ti content is less than 0.01% by mass, the effect of refining the ingot structure cannot be obtained. On the other hand, if it exceeds 0.05% by mass, the crystallized product (intermetallic compound) becomes coarse, and this becomes a stress concentration point at the time of molding and becomes a starting point of cracking. Therefore, when adding Ti, Ti content shall be 0.01-0.05 mass%.

(Balance: Al and inevitable impurities)
In addition to the above components, the fin material is composed of Al and inevitable impurities. As unavoidable impurities, in addition to the above-described Si, Mn, Cr, for example, Mg, Zn, Zr, Ce, Ga, V, which are contained in a metal base or an intermediate alloy within a generally known range. Ni and the like are allowed to contain up to 0.05% by mass, as long as the Al purity is not less than 99.30% by mass.

(Al purity: 99.30% by mass or more)
If the Al purity is less than 99.30% by mass, the color cracking increases and the corrosion resistance decreases with the increase of intermetallic compounds. Therefore, Al purity shall be 99.30 mass% or more.

(Thickness: less than 0.115 mm)
The present invention is directed to a fin material having a thickness of less than 0.115 mm from the viewpoint of reducing the thickness of the fin material in response to recent demands for compactness, weight reduction, and high performance of heat exchangers. Therefore, the plate thickness of the fin material is less than 0.115 mm. In the present invention, the average grain size of the sub-crystal grains is limited to 2.5 μm or less, and since there is little concern that it becomes a starting point of destruction even if it is thin, from the viewpoint that the features of the present invention can be further exhibited, It is preferably less than 0.100 mm, and more preferably 0.090 mm or less.

(Average grain size of sub-crystal grains: 2.5 μm or less)
In order to improve the color cracking resistance of the fin material having a thickness of less than 0.115 mm, it is necessary that the average grain size of the sub-crystal grains in the alloy be 2.5 μm or less. When the average grain size of the sub-crystal grains exceeds 2.5 μm, stress concentrates in the sub-crystal grains, the starting point of cracking increases, and the color cracking resistance decreases. Therefore, the average grain size of the sub-crystal grains is 2.5 μm or less. In addition, although a lower limit is not specified in particular, it may be 0 μm (that is, it does not have to include subcrystal grains). By setting it as such a range, even if it is a case where it is work-hardened by solid solution Mn, solid solution Cu, etc., generation | occurrence | production of a color crack can be suppressed and handling property can be aimed at.

Next, a method for measuring the average grain size of sub-crystal grains will be described.
First, orientation analysis is performed on the crystal structure of an image obtained by a scanning electron microscope (SEM) by an EBSD (Electron Back Scattered Diffraction Pattern) method. In the EBSD method, a sample is irradiated with an electron beam, and the crystal orientation is specified by utilizing reflected electron Kikuchi line diffraction generated at that time. For crystal orientation analysis, for example, OIM (Orientation Imaging Microscopy, (registered trademark)) manufactured by TSL can be used.
The average particle size of the subgrains, and calculates the number of subgrain The SEM / EBSD measurement data, by dividing the total area of the fin material by the number of subgrains, circle the area of each subgrain Is defined as the average grain size of the subgrains.

(Yield strength: more than 130 MPa and 155 MPa or less)
Since the fin material of the present invention is for a combination press, the yield strength is more than 130 MPa and not more than 155 MPa. When the proof stress is 130 MPa or less, the strength is insufficient and the handling property at the time of thinning is lowered. On the other hand, if it exceeds 155 MPa, the strength is too high and color cracking occurs during combination press molding. Accordingly, the proof stress exceeds 130 MPa and is 155 MPa or less. In addition, Preferably it is more than 130 MPa and 150 MPa or less, More preferably, it is more than 130 MPa and 140 MPa or less.
The proof stress can be measured by, for example, cutting out a tensile test piece according to JIS No. 5 from a fin material so that the tensile direction is parallel to the rolling direction and performing a tensile test according to JISZ2241.

  In addition, the average particle diameter and proof stress of a subcrystal grain can be controlled with a component composition and the manufacturing conditions mentioned later. Specifically, the average grain size of subgrains is the content of each component, homogenization heat treatment conditions (temperature and time), hot finish rolling finish temperature, cold work rate, temper annealing conditions (temperature and time) ) And the like are controlled by the content of each component, homogenization heat treatment conditions (temperature and time), temper annealing conditions (temperature and time), and the like.

The fin material according to the present invention may be provided with a surface treatment film on the surface of the fin material. The fin material surface means one side or both sides of the fin material.
(Surface treatment film)
Examples of the surface treatment film include a chemical film, a resin film, and an inorganic film depending on the use environment and application, and these may be combined (a resin film and an inorganic film are provided on the chemical film). In addition, examples of the resin film and the inorganic film include a corrosion-resistant resin film, a hydrophilic resin film, a hydrophilic inorganic film, and a lubricating resin film, and these may be appropriately combined.

  Examples of the chemical conversion film include phosphoric acid chromate. Examples of the corrosion-resistant resin film include epoxy-based, urethane-based, acrylic-based, and polyester-based resins, and the film thickness is preferably 0.5 to 5 μm. Examples of the hydrophilic film include water glass-based inorganic substances, resins containing polyacrylic acid or polyacrylate, resins containing sulfonic acid groups or sulfonic acid group derivatives, and the like. 0.05 to 10 μm is preferable. Examples of the lubricating resin film include resins containing polyether polyol, and the film thickness is preferably 0.1 to 10 μm.

  When combining two or more of a corrosion-resistant resin film, a hydrophilic resin film, a hydrophilic inorganic film, and a lubricating resin film, a hydrophilic resin film is provided on the surface side of the corrosion-resistant resin film. It is preferable that a lubricating resin film is provided on the surface side of the conductive inorganic film.

<Fin material manufacturing method>
The manufacturing method of the fin material according to the present invention is a manufacturing method of the above-described fin material, and includes a heat treatment process, a hot rolling process, a cold working process, and a temper annealing process. Furthermore, you may include an ingot preparation process and a surface treatment process as needed.
According to such a manufacturing method, the structure of the ingot is homogenized by the heat treatment process, and the hot rolled sheet is rolled without being recrystallized by the hot rolling process. Then, the cold working process does not cause the coarsening of the sub-crystal grains after the temper annealing, and the thickness is less than 0.115 mm. The temper annealing process gives the elongation and the fineness of the sub-crystal grains. Is promoted.
Hereinafter, each step will be described.

(Ingot production process)
The ingot production step is a step of producing an aluminum alloy ingot by melting and casting an aluminum alloy.
In the ingot production step, an ingot having a predetermined shape is produced from a molten metal in which the aluminum alloy having the chemical components described above is melted. The method for melting and casting the aluminum alloy is not particularly limited, and a conventionally known method may be used. For example, it can be melted using a vacuum induction furnace and cast using a continuous casting method or a semi-continuous casting method.

(Heat treatment process)
The heat treatment step is a step of subjecting the aluminum alloy ingot having the chemical composition of the aluminum alloy to a heat treatment (homogenization heat treatment) for 1 hour or more at a temperature of 450 to 500 ° C.
If the heat treatment temperature is less than 450 ° C., the ingot structure is not sufficiently homogenized. In addition, the hot workability is reduced. Further, the subcrystal grain size becomes large. On the other hand, if it exceeds 500 ° C., the fine intermetallic compound that is refined during heating becomes coarse, the sub-crystal grains become coarse, and the elongation decreases. Further, the yield strength is increased. In addition, the amount of solid solution increases. Therefore, the heat treatment temperature is set to 450 to 500 ° C. Moreover, since the said effect is acquired if heat processing is holding time 1 hour or more, it is not necessary to prescribe | regulate an upper limit in particular. On the other hand, since the effect is saturated after 10 hours, the heat treatment time is preferably within 24 hours economically.

(Hot rolling process)
The hot rolling step is a step of performing hot rolling after the heat treatment under the condition that the finish temperature of hot finish rolling is 250 ° C. or higher and lower than 300 ° C.
When the finish temperature of hot finish rolling is less than 250 ° C., the rollability of the material is lowered, and the rolling itself becomes difficult or the thickness control becomes difficult, and the productivity is lowered. On the other hand, at 300 ° C. or higher, since a recrystallized structure is formed in the hot-rolled sheet, a fibrous group of identical crystal orientations is generated after temper annealing, and constriction occurs during the piercing and burring process. In addition, the subcrystal grain size increases. Therefore, the finish temperature of hot finish rolling is 250 ° C. or higher and lower than 300 ° C. More preferably, it is 260-290 degreeC.

(Cold working process)
The cold working step is a step of performing cold working (cold rolling) with a cold working rate of 96% or more after the hot rolling.
After the hot rolling is completed, the cold working is performed once or a plurality of times, so that the fin material has a desired final thickness. However, if the cold working rate is less than 96%, the sub-crystal grains become coarse after temper annealing. Therefore, the cold working rate in cold working is 96% or more. Here, when intermediate annealing is performed in the middle of cold working, the cold working rate is a working rate from the intermediate annealing to the final plate thickness. Therefore, if the intermediate annealing is performed, it becomes difficult to obtain a cold working rate of 96% or more, so the intermediate annealing is not performed. In addition, since a cold work rate is so preferable that it is high, there is no upper limit in particular.

(Refining annealing process)
The temper annealing step is a step of performing temper annealing (finish annealing) that is held at a temperature of 135 to 210 ° C. for 1 to 6 hours after the cold working.
If the temper annealing temperature is less than 135 ° C., sufficient elongation cannot be obtained. On the other hand, when it exceeds 210 ° C., recrystallized grains are generated after annealing, and cracks are generated starting from this. Further, the refinement of sub-crystal grains is not promoted. Furthermore, handling properties are lowered. Therefore, the temperature of temper annealing is 135-210 degreeC, Preferably you may be 150 degreeC or more and less than 180 degreeC. In addition, it is normal to perform temper annealing for 1 hour or more, and since an effect will be saturated when 6 hours are exceeded, holding time shall be 1 to 6 hours.

(Surface treatment process)
The surface treatment step is a step of subjecting the fin material after the temper annealing to a surface treatment.
In the surface treatment step, when a chemical conversion film is formed, it can be performed by a chemical conversion treatment using a normal coating type or reactive type chemical. In the case of forming a resin film such as a corrosion-resistant resin film, a hydrophilic resin film, or a lubricating resin film, it can be carried out by applying and drying using a roll coater.

  In carrying out the present invention, other steps may be included between or before and after each step as long as they do not adversely affect each step. For example, a foreign material removing process for removing foreign substances such as dust, a chamfering process for chamfering an ingot, a temper annealing process and a surface treatment process, and machining that is appropriately performed as a fin material. A process or the like may be included.

And the fin material manufactured in this way is shape | molded by the shaping | molding method by a combination system.
Combination molding (combination press) is stretched in the first process, drawn in the second process, punched and hole expanded in the third process (piercing and burring), ironed in the fourth process, and flared in the fifth process. Is to be applied. And since the fin material of this invention is excellent in color cracking resistance, generation | occurrence | production of the color crack at the time of the shaping | molding process by a combination system can be suppressed, and also handling property can be improved.

  As mentioned above, although the form for implementing this invention has been described, the Example which confirmed the effect of this invention is demonstrated concretely compared with the comparative example which does not satisfy | fill the requirements of this invention below. In addition, this invention is not limited to this Example.

[Sample preparation]
(Examples or Reference Examples No. 1 to 10, Comparative Examples No. 11 to 22)
An aluminum alloy having the composition shown in Table 1 was melted and cast into an ingot, and the ingot was subjected to chamfering and then subjected to homogenization heat treatment at 480 ° C. for 4 hours. The heat-treated ingot was hot-rolled by controlling the finishing temperature of hot finish rolling to be 270 ° C. to obtain a hot-rolled sheet having a thickness of 3.0 mm. Further, after cold rolling at a cold working rate of about 97.0% or 97.3%, respectively, the sheet thickness was set to 90 μm and 80 μm, and then subjected to temper annealing at the temperature and holding time shown in Table 1. Fin material was used.

(Examples or Reference Examples No. 23 to 28, Comparative Examples No. 29 to 36)
Aluminum alloys shown in Table 2 (Alloys A, B, and C corresponding to Table 1) were melted and cast to form ingots, and after the surfaces were subjected to face grinding, homogenization heat treatment and hot rolling were performed. A hot rolled plate having a thickness of 3.0 mm was used. Furthermore, no. Except for 36, the steel sheet was cold-rolled at a cold working rate of about 97.0% or 97.3% to obtain sheet thicknesses of 90 μm and 80 μm, and then subjected to temper annealing to obtain a fin material. No. In No. 36, a hot-rolled sheet having a thickness of 3.0 mm was subjected to cold rolling at a cold working rate of 50%, and then subjected to intermediate annealing at 360 ° C. for 3 hours using a batch furnace. Thereafter, cold rolling was performed at a cold working rate of about 94.0% or 94.7%, respectively, so that the plate thickness was 90 μm and 80 μm, and then temper annealing was performed to obtain a fin material. Table 2 shows the conditions for the homogenization heat treatment, the finish temperature of the hot finish rolling, and the temper annealing. In addition, No. 31 is a thing which could not manufacture a fin material.

(Examples or Reference Examples No. 37 to 40, Comparative Examples No. 41 to 44)
No. in Table 2 No. 23, which is the same fin material as that of No. 23. 37, 38, No. 2 in Table 2. No. 28, which is the same fin material as No. 28. 39, 40, No. 2 in Table 2. No. 30 which is the same fin material as that of No. 30. 41, 42, No. 2 in Table 2. No. 33, which is the same fin material as No. 33. The following surface treatments (Nos. 1 to 4) were performed on 43 and 44.

No. 1: Surface treatment under the same conditions as in Comparative Example 1 of JP 2010-223520 A (comprising a chemical conversion film, a hydrophilic film, and a lubricating film in this order)
No. 2: Surface treatment under the same conditions as Example 1 of Japanese Patent No. 3383914 (comprising a chemical conversion film, a hydrophilic film, and a lubricating resin film in this order)
No. 3: Surface treatment under the same conditions as in Example 1 of JP 2008-224204 (comprising a chemical conversion film, a corrosion-resistant resin film, and a hydrophilic film in this order)
No. 4: Surface treatment under the same conditions as Comparative Example 21 of JP 2010-223514 A (comprising a chemical conversion film and a corrosion-resistant resin film in this order)

  The component composition is shown in Table 1, and the production conditions are shown in Tables 2 and 3. In the table, those not satisfying the scope of the present invention are indicated by underlining the numerical values, and those not containing a component are indicated by “−”. In addition, No. Since 31 was not able to manufacture the fin material, “-” is written in the temper annealing column. No. 16 is based on the aluminum alloy fin material based on the description of Patent Document 1 (Invention Example 1 of Table 2 (however, the hot rolling end temperature and the plate thickness after hot rolling (3.5 mm) are different), No. 13 is based on an aluminum alloy fin material based on the description of Patent Document 2 (Invention Example 4 in Table 1 (however, the processing method (drawing process) is different)), and No. 17 is a patent. No. 35 is an aluminum alloy based on the description of Patent Document 4, which is based on an aluminum alloy fin material based on the description in Reference 3 (Invention Example 3 in Table 1 (however, the processing method (drawless processing) is different)) It is based on a fin material (Invention Example 11 in Table 2 (however, the plate thickness after cold rolling (0.115 mm thickness) is different)).

  Next, the average grain size of the sub-crystal grains was measured by the following method as the structure of the fin material. Furthermore, strength and elongation were measured by the following methods.

[Average grain size of sub-crystal grains]
The average grain size of the sub-crystal grains is obtained by analyzing the orientation of the crystal structure of a scanning electron microscope (SEM) image obtained by photographing the sample surface at an observation magnification of 1,000 times by the EBSD method at a measurement interval of 0.10 μm. Based on the calculation, it was automatically calculated on OIM (Orientation Imaging Microscopy, (registered trademark)) software manufactured by TSL. That is, by dividing the number of sub-grains that have been counted total area of the fin material by SEM / EBSD measurement data, the diameter defined as the average grain size of sub crystal grains in the case where the area of each subgrains approximate a circle did. The number of subgrains, was counted Grains misorientation between the adjacent crystal grains surrounded by 2 ° or more grain boundaries as subgrains.

[Tensile strength, 0.2% proof stress, elongation]
A tensile test piece according to JIS No. 5 was cut out from the fin material so that the tensile direction was parallel to the rolling direction. A tensile test according to JISZ2241 was performed on this test piece, and tensile strength, 0.2% yield strength, and elongation were measured. In addition, the tensile speed in evaluation of a present Example , a reference example, and a comparative example was performed at 5 mm / min.

[Evaluation of color cracking resistance]
The produced fin material was press-molded by combination molding to evaluate color cracking resistance.
The color cracking resistance evaluation was evaluated by visually counting the cracks generated in the collar portion with respect to 400 holes of the press-formed product.
“Number of cracks / 400 × 100 (%)” was defined as the occurrence rate, (less than 10%) (◯), and 10% or more (×). And what was ((circle)) in all 90 micrometers and 80 micrometers was set as the pass.

[Handling evaluation]
FIG. 1A is a perspective view and FIG. 1B is a side view for explaining a handling property evaluation method. A large number of fin materials 1 (200 mm length × 20 mm width) provided with 10 hole collars are laminated at a pitch of 1.6 mm, and 10 copper pipes 2 having an outer diameter of 7 mm and an inner diameter of 6 mm are passed through the hole collars. A heat exchanger was manufactured by inserting a burette inside 2 and fixing it by expanding the tube.
A stainless steel block 3 having a bottom surface of 20 mm square was attached to the load cell, placed on the side of the heat exchanger, a compressive load was applied, and a load at which the fin material 1 started to buckle was measured.
When the load for starting buckling was 4500 N or more, it was determined that the handling property was good (◯), and when it was less than 4500 N, it was determined that the handling property was not good (×).

  The measurement results and evaluation results are shown in Tables 1-3. In the table, those that do not satisfy the scope of the present invention are indicated by underlining numerical values, and those that cannot be measured and evaluated because the fin material cannot be manufactured are indicated by “−”.

(Evaluation by ingredients)
As shown in Table 1, No. 1 which is an example or a reference example . Nos. 1 to 10 were excellent in color crack resistance and handling properties in order to satisfy the scope of the present invention or for reference examples .

On the other hand, No. which is a comparative example. Since 11 to 22 did not satisfy the scope of the present invention, the following results were obtained.
No. In No. 11, since the Si content exceeded the upper limit, coarse intermetallic compounds increased and the color cracking resistance was poor.

  No. In No. 12, since the Fe content was less than the lower limit, the subcrystal grain size was large, and the color cracking resistance and handling properties were inferior. No. In No. 13, since the Fe content exceeded the upper limit and the Al purity was less than the lower limit, coarse intermetallic compounds increased and the color crack resistance was poor. No. In No. 14, since the Al purity was less than the lower limit, coarse intermetallic compounds increased and the color cracking resistance was poor.

  No. No. 15 was inferior in color cracking resistance due to work hardening because the Cu content exceeded the upper limit. No. In No. 16, since the Mn content exceeded the upper limit, coarse intermetallic compounds increased and the color cracking resistance was poor. No. 17 and no. No. 18, since the Mn content exceeds the upper limit, coarse intermetallic compounds increase, and because the temperature of the temper annealing exceeds the upper limit, the subcrystal grain size increases, and the proof stress is less than the lower limit. It was inferior in color cracking resistance and handling property.

  No. In No. 19, since the Cr content exceeded the upper limit, coarse intermetallic compounds increased and the color cracking resistance was poor. No. No. 20, since the Ti content exceeded the upper limit, coarse intermetallic compounds increased and the color cracking resistance was poor. No. In No. 21, since the Ti content exceeded the upper limit, coarse intermetallic compounds increased, and the temper annealing temperature exceeded the upper limit. No. In No. 22, since the Fe content exceeded the upper limit, coarse intermetallic compounds increased and the color cracking resistance was poor.

(Evaluation by manufacturing method)
As shown in Table 2, No. 1 as an example or reference example . Nos. 23 to 28 were excellent in color crack resistance and handling properties in order to satisfy the scope of the present invention or for reference examples .

On the other hand, No. which is a comparative example. Since 29-36 did not satisfy the scope of the present invention, the following results were obtained.
No. In No. 29, since the temperature of the homogenization heat treatment was less than the lower limit, the subcrystal grain size was large, the yield strength was low, and the handling property was poor. No. In No. 30, since the temperature of the homogenization heat treatment exceeded the upper limit value, the sub-crystal grains became large and the color cracking resistance was inferior.

  No. In No. 31, the finish temperature of the hot finish rolling was less than the lower limit, so that the rolling itself was difficult and the fin material could not be produced. No. In No. 32, since the finish temperature of hot finish rolling exceeds the upper limit value, the sub-crystal grains become large, the yield strength is low, and the color crack resistance and handling properties are poor. No. No. 33 had a mixed grain structure because the tempering temperature exceeded the upper limit, and the proof stress was less than the lower limit, resulting in poor color cracking resistance and handling properties.

  No. In No. 34, since the tempering temperature was less than the lower limit, the proof stress exceeded the upper limit, and cracking occurred in the overhanging process. No. In No. 35, the temperature of the homogenization heat treatment exceeded the upper limit value, so the sub-crystal grains were large and the color cracking resistance was poor. No. In No. 36, since the intermediate annealing was performed, the cold working rate was less than the lower limit. Therefore, the average grain size of the sub-crystal grains exceeded the upper limit value, and the proof stress became less than the lower limit value, resulting in poor color cracking resistance and handling properties.

(Evaluation when surface treatment is applied)
No. The color cracking resistance of the fin material subjected to the surface treatment in 37 to 44 was the same as that of the fin material not subjected to the surface treatment.

3
In addition, No. The fin materials of 16, 13, 17, and 35 are assumed to be the conventional aluminum alloy fin materials described in Patent Document 1, Patent Document 2, Patent Document 3, and Patent Document 4, respectively. As shown in this example, these conventional aluminum alloy fin materials do not satisfy a certain level in the above evaluation. Therefore, this example objectively revealed that the aluminum alloy fin material for a heat exchanger for a combination press according to the present invention is superior to the conventional aluminum alloy fin material.

  As mentioned above, although the fin material which concerns on this invention, and its manufacturing method were shown in detail, showing embodiment and an Example, the meaning of this invention is not limited to an above-described content. Needless to say, the contents of the present invention can be widely modified and changed based on the above description.

1 Fin material 2 Copper tube 3 Block

Claims (7)

Fe: 0.0010 to 0.4 mass%, Cu: 0.005 to 0.01 mass%, the balance is made of Al and inevitable impurities, and the Al purity is 99.30 mass% or more from an aluminum alloy. An aluminum alloy fin material for a heat exchanger for a combination press comprising:
The plate thickness of the aluminum alloy fin material for the heat exchanger for combination press is less than 0.115 mm, the average grain size of the sub-crystal grains is 2.5 μm or less, and the 0.2% proof stress is more than 130 MPa and 155 MPa or less. Features Aluminum alloy fin material for heat exchangers for combination presses. The chemical components of the aluminum alloy, Si: less than 0.20 wt%, Mn: less than 0.015 wt%, Cr: for combination press according to claim 1, characterized in that 0.015 wt% or less Aluminum alloy fin material for heat exchangers.   The aluminum alloy fin material for a heat exchanger for a combination press according to claim 1 or 2, wherein the chemical component of the aluminum alloy further contains Ti: 0.01 to 0.05 mass%.   4. The aluminum alloy fin for a heat exchanger for a combination press according to claim 1, wherein the plate thickness of the aluminum alloy fin material for the heat exchanger for the combination press is less than 0.100 mm. 5. Wood.   4. The aluminum alloy fin for a heat exchanger for a combination press according to claim 1, wherein a plate thickness of the aluminum alloy fin material for the heat exchanger for the combination press is 0.090 mm or less. 5. Wood. 4. The aluminum alloy fin material for a heat exchanger for combination press according to claim 1, wherein the plate thickness of the aluminum alloy fin material for the heat exchanger for combination press is 80 μm or less. 5. . The surface of the fin material is provided with one or more of a chemical conversion film, a corrosion-resistant resin film, a hydrophilic resin film, a hydrophilic inorganic film, and a lubricating resin film. An aluminum alloy fin material for a heat exchanger for a combination press according to claim 1.

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