JP5764240B2 - Aluminum alloy fin material for heat exchanger for combination press - Google Patents

Description

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

  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.

  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.

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 intended for a combination press excellent in color cracking resistance and 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.

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: 0.05 mass% or less (including 0 mass%) , Si : 0.15 mass% or less (including 0 mass%), Mn: less than 0.015 mass% (including 0 mass%), Cr: 0.015 mass% or less (including 0 mass%), An aluminum alloy fin material for a heat exchanger for a combination press, comprising the balance of Al and inevitable impurities, and an Al purity of 99.30% by mass or more, wherein the aluminum alloy fin material for the heat exchanger for the combination press a thickness of less than 0.115 mm, to wherein the average particle diameter of the subgrains is 2.5μm or less and yield strength 100~ 122 N / mm ² .

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. Moreover, the increase in an intermetallic compound is suppressed by prescribing Al purity. And the elongation in the fin material of thickness less than 0.115 mm increases by making the average particle diameter of a subcrystal grain into 2.5 micrometers or less. Further, by setting the proof stress to 100 to 122 N / mm ² , the strength becomes appropriate as a fin material for a combination press. Moreover, the coarsening of the crystallized substance (namely, intermetallic compound) is suppressed by suppressing Si, Mn, and Cr below predetermined amount or less than predetermined amount.

Combination press heat exchanger use aluminum alloy fin material according to the present invention, the chemical composition of the aluminum alloy, C u: the 0.005 to 0.05 wt%, characterized in Rukoto to Yusuke free.

According to such a configuration, by adding a predetermined amount of Cu, the rigidity at the time of thinning is ensured.

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 may be provided with a surface treatment film on the surface of the fin material. Examples of the surface treatment film include a corrosion-resistant film, a hydrophilic film, and a lubricating film.
According to such a structure, the characteristics according to use environment, a use, etc., such as corrosion resistance, hydrophilicity, and moldability, can be improved.

  A method for producing an aluminum alloy fin material for a heat exchanger for a combination press is a method for producing an aluminum alloy fin material for a heat exchanger for a combination press (not provided with a surface treatment film), wherein the chemical composition of the aluminum alloy A heat treatment step of subjecting the aluminum alloy ingot to heat treatment at a temperature of 450 to 500 ° C. for 1 hour or more, and after the heat treatment, a hot finish rolling is performed under a condition that an end temperature of hot finish rolling is 250 ° C. or more and less than 300 ° C. 1 to 6 at a temperature of 180 to 260 ° C. after the cold working, a hot working step for rolling, a cold working step for performing cold working with a cold working rate of 96% or more after the hot rolling, and And a temper annealing step for performing a temper annealing that maintains time.

  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. And it is made into thickness less than 0.115mm without producing coarsening of a subcrystal grain after refining annealing by a cold working process, and elongation is given by refining annealing process, and refinement of a subcrystal grain Is promoted.

  The aluminum alloy fin material for a heat exchanger for a combination press according to the present invention can suppress color cracking when being formed. 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.

  Moreover, the manufacturing method of the aluminum alloy fin material for heat exchangers for combination presses can manufacture the aluminum alloy fin material for heat exchangers excellent in color cracking resistance.

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, the balance being Al and inevitable impurities, and an aluminum alloy having an Al purity of 99.30% by mass or more. And the thickness of this fin material is less than 0.115 mm, the average particle diameter of a subcrystal grain is 2.5 micrometer or less, and the proof stress is prescribed | regulated to 100-130 N / mm < ² >. Moreover, about the chemical component of an aluminum alloy, it is preferable to contain a predetermined amount of Cu as necessary, and to suppress Si, Mn, Cr to a predetermined amount or less or less than a predetermined amount among unavoidable impurities contained in the aluminum alloy. . 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. If the Fe content is less than 0.010% by mass, the above effects cannot be obtained, and the color cracking property is inferior in press molding. On the other hand, if it exceeds 0.4% by mass, the strength becomes too high, 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 rigidity when thinned, it is desirable to add Cu further. 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, when adding Cu in order to ensure rigidity, the Cu content is set to 0.005 to 0.05 mass%. More preferably, it is 0.01-0.05 mass%.

(Si: 0.15 mass% or less (including 0 mass%))
Si is an element mixed as an unavoidable impurity. However, if the Si content exceeds 0.15% 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 Si, Si content shall be 0.15 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 0.005 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. Moreover, the proof stress is increased. 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 downsizing, weight reduction, and high performance of heat exchangers. Therefore, the thickness of the fin material is less than 0.115 mm.

(Average grain size of sub-crystal grains: 2.5 μm or less)
In order to increase the elongation 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. If the average grain size of the sub-crystal grains exceeds 2.5 μm, sufficient elongation of the fin material cannot be obtained. 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, generation | occurrence | production of a color crack can be suppressed even if it is a case where it is a case where it carries out work hardening with solute Mn, solute Cu, etc.

Next, a method for measuring the average grain size of sub-crystal grains will be described.
First, orientation analysis of a scanning electron microscope (SEM) structure is performed 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. ^™ ) manufactured by TSL can be used.
The average grain size of the sub-crystal grains is calculated from the SEM / EBSD measurement data, the number of crystal grains is calculated, the total area of the fin material is divided by the number of crystal grains, and the area of each crystal grain is approximated to a circle. The diameter of the case is defined as the average grain size of the subgrains.

(Yield strength: 100 to 130 N / mm ² )
Since the fin material of the present invention is for a combination press, the yield strength is 100 to 130 N / mm ² . When the yield strength is less than 100 N / mm ² , the strength is insufficient, and color cracks occur during combination press molding. On the other hand, if it exceeds 130 N / mm ² , the strength is too high and color cracks occur during combination press molding. Therefore, the yield strength is 100 to 130 N / mm ² . Incidentally, preferably 100 N / mm ² or more 130N / mm lower than ^2, more preferably less than 100 N / mm ² or more 120 N / mm ^2.
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.
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. Moreover, the yield strength is lowered. 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 180 to 260 ° C. for 1 to 6 hours after the cold working.
If the tempering annealing temperature is less than 180 ° C., sufficient elongation cannot be obtained. Moreover, the proof stress is increased. On the other hand, when it exceeds 260 ° 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, the yield strength is lowered. Therefore, the temperature of temper annealing is set to 180-260 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.

  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 21)
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. This homogenized ingot was hot-rolled by controlling the finish 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.

(Example No. 22-27, Comparative example No. 28-35)
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 35, cold rolling was performed at a cold working rate of about 97.0% or 97.3% to make the plate thickness 90 μm and 80 μm, respectively, and then subjected to temper annealing to obtain a fin material. No. In No. 35, a hot rolled plate 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. 30 is a thing which could not manufacture a fin material.

(Example No. 36-39, comparative example No. 40-43)
No. in Table 2 No. 22 which is the same fin material as that of No. 22. 36, 37, No. 2 in Table 2. No. 27, which is the same fin material as No. 27. 38, 39, No. 2 in Table 2. No. 29, which is the same fin material as No. 29. 40, 41, No. 2 in Table 2. No. 32, which is the same fin material as No. 32. The following surface treatments (Nos. 1 to 4) were performed on 42 and 43.

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 30 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. 34 is an aluminum alloy based on the description of Patent Document 4, which is based on the 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 based on the data obtained by analyzing the orientation of the scanning electron microscope (SEM) structure 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. Calculation was performed by automatic calculation on OIM (Orientation Imaging Microscopy.TM) software. That is, the total area of the fin material was divided by the number of crystal grains counted by SEM / EBSD measurement data, and the diameter when the area of each crystal grain was approximated to a circle was defined as the average grain size of the subcrystal grains. As for the number of crystal grains, a crystal grain surrounded by a crystal grain boundary whose orientation difference between adjacent crystal grains is within 2 ° was counted as one crystal grain.

[Strength and 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]
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 an occurrence rate, and the occurrence rate was defined as (◎) when less than 3%, (◯) when 3% or more and less than 5%, and (×) when 5% or more. And what was either ((double-circle)) or ((circle)) in all 90 micrometers and 80 micrometers was set as the pass.

  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 . 1 to 10 were excellent in color cracking resistance 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 21 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 was poor. 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, the yield strength exceeded the upper limit, and the color cracking resistance was poor. No. In No. 14, since the Al purity was less than the lower limit, coarse intermetallic compounds increased, the proof stress exceeded the upper limit, and the color crack resistance was inferior.

  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. No. 17, since the Mn content exceeds the upper limit, coarse intermetallic compounds increase, and the temperature of the temper annealing exceeds the upper limit, so that the subcrystal grain size increases and the proof stress is less than the lower limit. It was inferior in color cracking resistance.

  No. In No. 18, since the Cr content exceeded the upper limit, coarse intermetallic compounds increased and the color cracking resistance was poor. No. In No. 19, since the Ti 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 Fe content exceeded the upper limit, coarse intermetallic compounds increased, the proof stress exceeded the upper limit, and the color crack resistance was inferior.

(Evaluation by manufacturing method)
As shown in Table 2, the example No. Since 22-27 satisfy | filled the range of this invention, it was excellent in the color cracking-proof property.

On the other hand, No. which is a comparative example. Since 28 to 35 did not satisfy the scope of the present invention, the following results were obtained.
No. No. 28 was inferior in color cracking resistance because the temperature of the homogenization heat treatment was less than the lower limit value, so that the subcrystal grain size was large. No. No. 29 was inferior in color cracking resistance because the temperature of the homogenization heat treatment exceeded the upper limit value, so that the subcrystal grain size was increased, the proof stress exceeded the upper limit value.

  No. No. 30, because the finish temperature of hot finish rolling was less than the lower limit, rolling itself was difficult, and the fin material could not be manufactured. No. No. 31, because the finish temperature of hot finish rolling exceeds the upper limit, the subcrystal grain size was large and the color cracking resistance was poor. No. No. 32 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.

  No. In No. 33, since the tempering temperature was less than the lower limit, the yield strength exceeded the upper limit, and cracking occurred in the overhanging process. No. No. 34 was inferior in color cracking resistance because the temperature of the homogenization heat treatment exceeded the upper limit value, so that the subcrystal grain size was increased, the yield strength exceeded the upper limit value. No. In No. 35, since the intermediate annealing was performed, the cold working rate was less than the lower limit. Therefore, the average grain size of the subcrystalline grains exceeded the upper limit value, and the proof stress became less than the lower limit value, resulting in poor color cracking resistance.

(Evaluation when surface treatment is applied)
No. The color cracking resistance of the fin material subjected to the surface treatment in 36 to 43 was the same as that of the fin material not subjected to the surface treatment.

  In addition, No. The fin materials of 16, 13, 17, and 34 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.

Claims (6)

Fe: 0.010 to 0.4 mass% , Cu: 0.05 mass% or less (including 0 mass%) , Si: 0.15 mass% or less (including 0 mass%), Mn: 0 Less than 0.015 mass% (including 0 mass%), Cr: 0.015 mass% or less (including 0 mass%), the balance is made of Al and inevitable impurities, and the Al purity is 99.30 mass% An aluminum alloy fin material for a heat exchanger for a combination press made of the above aluminum alloy,
The thickness of the aluminum alloy fin material for a heat exchanger for combination press is less than 0.115 mm, the average grain size of sub-crystal grains is 2.5 μm or less, and the proof stress is 100 to 122 N / mm ^2. Aluminum alloy fin material for heat exchangers for combination presses. Wherein the chemical composition of the aluminum alloy, C u: 0.005 to 0.05 Combination press heat exchanger use aluminum alloy fin material of claim 1, mass%, characterized in Rukoto to Yusuke free.   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 material for a heat exchanger for a combination press according to claim 1, wherein a thickness of the aluminum alloy fin material for the heat exchanger for the combination press is 90 μm or less. 5.   The aluminum alloy fin material for a heat exchanger for combination press according to any one of claims 1 to 3, wherein the thickness of the aluminum alloy fin material for the heat exchanger for combination press is 80 µm or less.   The aluminum alloy fin material for a heat exchanger for a combination press according to any one of claims 1 to 5, wherein a surface treatment film is provided on the surface of the fin material.