MX2008000955A - High strength aluminum alloy fin material and method of production of same. - Google Patents

Abstract

A heat exchanger use high strength aluminum alloy fin material having a high strength and excellent in thermal conductivity, erosion resistance, sag resistance, sacrificial anodization effect, and self corrosion resistance, characterized by containing Si: 0.8 to 1.4 wt%, Fe: 0.15 to 0.7 wt%, Mn: 1.5 to 3.0 wt%, and Zn: 0.5 to 2.5 wt%, limiting the Mg as an impurity to 0.05 wt% or less, and having a balance of ordinary impurities and Al in chemical composition, having a metal structure before brazing of a fibrous crystal grain structure, a tensile strength before brazing of not more than 240 MPa, a tensile strength after brazing of not less than 150 MPa, and a recrystallized grain size after brazing of 500 ??m or more.

Description

HIGH RESISTANCE ALUMINUM ALLOY FIN MATERIAL AND THEIR PRODUCTION METHOD TECHNICAL FIELD The present invention relates to an aluminum alloy fin material for use in excellent heat exchanger in brazing and a method for the production thereof, more particularly refers to an aluminum alloy fin material used for an exchanger such as a radiator, car heater, car air conditioner, etc. wherein the fins and a functional fluid passage material are brazed together, in which the heat exchanger aluminum alloy fin material the strength before brazing is suitable, so as to facilitate the formation of the fin, is To say, the resistance before the brazing is not too high which makes the formation of the fin difficult, the resistance after the brazing is high, and the thermal conductivity, the resistance to erosion, the buckling resistance, the sacrificial anodizing effect , and the resistance to self-corrosion are excellent, and a method for the production of it.

PREVIOUS TECHNIQUE A car radiator, an air conditioner, an intermediate heat exchanger, oil cooler, or other heat exchanger is assembled by brazing together with a functional fluid flow material comprised of an alloy based on Al-Cu, alloy based on Al -Mn, alloy based on Al-Mn-Cu, etc. and the fins comprised of an alloy based on Al-Mn. The fin material is required to have a sacrificial anodizing effect in order to avoid corrosion of the functional fluid passage material and it is required to have excellent buckling resistance and erosion resistance in order to avoid deformation or erosion of the brazing material due to heating at high temperature in the brazing time. JIS 3003, JIS 3203, and other aluminum alloys based on Al-Mn are used as fin materials because the Mn acts effectively to prevent deformation or erosion of the brazing material in the brazing time. Al-fin alloy material based on Al-Mn can be given a sacrificial anodization effect through the addition method of Zn, Sn, In, etc. to this alloy to make it electrochemically anodic (Japanese Patent Publication (A) No. 62-120455) etc. To further improve the resistance to warping at high temperature (resistance to buckling), there is a method to introduce Cr, Ti, Zr, etc. In the alloy based on Al-Mn (Japanese Patent Publication (A) No. 50-118919) etc. However, recently, it is required that heat exchangers become increasingly lighter and lower cost.

The requirement to thin the functional fluid passage material, the fin material, and other heat exchanger materials is increasing. However, if, for example, by making the fins thinner, the cross-sectional area of thermal conduction is reduced, so that the heat exchanger performance decreases and the final heat exchanger has problems of strength and durability. Therefore, a much higher thermal conduction yield, strength after brazing, buckling resistance, erosion resistance, and self-corrosion resistance are desirable. In the alloys based on conventional Al-Mn, the Mn dissolves in the matrix due to the heating in the brazing time, so that the thermal conductivity decreases. As a material to solve this difficulty, it has been proposed, an aluminum alloy which limits the content of Mn to not more than 0.8% by weight and which contains Zr: 0.02 to 0.2% by weight and Si: 0.1 to 0.8% by weight (Japanese Patent Publication (B2) No. 63-23260). This alloy has an improved thermal conductivity, although the amount of Mn is small, so that the resistance after brazing is insufficient and the fins easily collapse or deform during use as a heat exchanger. In addition, the potential is not anodic enough, so that the sacrifice anodization effect is reduced. On the other hand, by accelerating the cooling rate when an aluminum alloy melt is molded into a slab, even if the contents of Si and Mn etc. are made. 0.05 to 1.5% by mass, the recrystallization of the intermetallic compounds in them can be reduced in size up to a maximum size of no more than 5 μm. It has been proposed to improve the fatigue properties of the fin material by lamination of this slab (Japanese Patent Publication (A) No. 2001-226730). However, this invention has the purpose of improving the fatigue life. While the development of the thinner slab is described as a means to accelerate the rate of cooling when the slab is emptied, no specific description of such thin slab continuous casting could be found by means of a dual-band casting machine. operations on an industrial scale.

DESCRIPTION OF THE INVENTION An object of the present invention is to provide an aluminum alloy fin material for use in heat exchanger having adequate strength before brazing allowing easy formation of the fin, which has high strength after brazing and also has excellent buckling strength , resistance to erosion, resistance to self-corrosion and sacrificial anodization and a method for its production.

To achieve such an object, the high strength aluminum alloy fin material for use in the heat exchanger of the present invention is characterized by containing Si: 0.8 to 1.4% by weight, Fe: 0.15 to 0.7% by weight, Mn: 1.5 up to 3.0% by weight, and Zn: 0.5 to 2.5% by weight, limiting Mg as an impurity to 0.05% by weight or less, and the remainder being ordinary impurities and Al in chemical composition, which has a metallic structure before the brazing of a fibrous glass grain structure, a tensile strength before brazing of no more than 240 MPa, a tensile strength after brazing of no more than 150 MPa, and a grain size recrystallized after the brazing of 500 μm or more. A first method of producing a high strength aluminum alloy fin material for use in the heat exchanger of the present invention is characterized by casting a melt having the chemical composition of the fin material for continuous casting and winding in a roll, a thin slab having a thickness of 5 to 10 mm by means of a double-band casting machine, cold rolling of this slab to a sheet thickness of 1.0 to 6.0 mm, treating this sheet by primary intermediate annealing at 200 to 350 ° C, further cold-laminating the sheet to a sheet thickness of 0.05 to 0.4 mm, treating the sheet by secondary intermediate annealing at 360 to 450 ° C, and cold-rolling the sheet at a rolling speed. in cold final of 10% to less than 50% for a final film thickness of 40 to 200 μm. A second method for producing a high strength aluminum alloy fin material for use in the heat exchanger of the present invention is characterized by casting a melt having the chemical composition of the fin material for continuous casting and winding in a roll a thin slab having a thickness of 5 to 10 mm by means of a double-band casting machine, cold-rolled this slab to a sheet thickness of 1.0 to 6.0 mm, treat this sheet by primary annealing to 200 up to 450 ° C, additionally cold-laminate the sheet to a sheet thickness of 0.08 to 2.0 mm, treat the sheet by secondary intermediate annealing at 360 to 450 ° C, cold-laminate the sheet by a cold-rolling speed from 50% to 96% to a final film thickness of 40 to 200 μm, and treat the sheet by means of final annealing at 200 to 400 ° C. In the first and second methods, the primary intermediate annealing is preferably carried out by means of a continuous annealing furnace with a temperature increase of 100 ° C / min or more and with a retention temperature of 400 to 500 ° C. and a retention time of 5 minutes. In the first and second methods, in the stages after the primary intermediate annealing, after the secondary annealing and after the final annealing (before the brazing), the metallic structure is preferably a fibrous crystalline grain structure. According to the present invention, by limiting the chemical composition and the crystalline grain structure and the tensile strength before and after brazing, in this way, a high strength aluminum alloy fin material is obtained for use in heat exchanger that has high strength and excellent thermal conductivity, erosion resistance, buckling resistance, sacrificial anodizing effect, and self-corrosion resistance. This aluminum alloy fin material can be produced by means of the first and second methods.

BEST MODE TO CARRY OUT THE INVENTION The inventors worked to develop an aluminum alloy fin material that satisfies the requirement of the thickness reduction of the fin materials for use in a heat exchanger by comparing the laminated materials with the conventional DC slab cast lines and the materials Laminates from double-band casting lines for strength properties, thermal conductivity, buckling resistance, erosion resistance, self-corrosion resistance, and sacrificial anodization effect and study the relationships between compositions, conditions of intermediate annealing, reduction rates, and final annealing in various manners and thus completed the present invention. The meanings and reasons for limiting the ingredients of the alloy of the aluminum alloy fin material for use in the heat exchanger of the present invention will be explained below. [Yes: 0.8 to 1.4% by weight] If, in copresence of Fe and Mn, it forms compounds based on Al- (Fe-Mn) -If the submicron level in the brazing time in order to improve the strength, it reduces Simultaneously the amount of solute Mn, and improves the thermal conductivity. If the content of Si is less than 0.8% by weight, the effect is insufficient, while if it is more than 1.4% by weight, the fin material is susceptible to fusion in the brazing time. Therefore, the preferable content range is from 0.8 to 1.4% by weight. The most preferable content of Si is 0.9 to 1.4% by weight in range. [Fe: 0.15 to 0.7% by weight] Fe, in copresence of Mn and Si, compound form based on Al- (Fe-Mn) -Si of submicron level in the brazed time in order to improve the resistance, reduces Simultaneously manages the amount of solute Mn, and improves the thermal conductivity. If the content of Fe is less than 0.15% by weight, high purity metal would be required, so production costs would increase, so that said content is not preferred. If it is more than 0.7% by weight, at the time of casting the alloy, thick crystals are formed based on AI- (Fe-Mn) -Si and the sheet material becomes difficult to produce. Therefore, the preferable range is 0.15 to 0.7% by weight. The most preferable content of Fe is 0.17 to 0.6% by weight in range.

[Mn: 1.5 to 3.0% by weight] Mn, in copresence of Fe and Si, is precipitated at a high density as compounds based on AI- (Fe-Mn) -If submicron level in the brazed time and improves the resistance of the alloy material after brazing. In addition, crystals based on AI- (Fe-Mn) -Si of submicron level have a strong action in the inhibition of recrystallization, so the recrystallized grains become rough of 500 μm or larger and the resistance is improved to buckling and resistance to erosion. If Mn is less than 1.5% by weight, its effect is not sufficient, while if it is greater than 3.0% by weight, thick crystals are formed based on AI- (Fe-Mn) -Si at the time of casting of the alloy and the sheet material becomes difficult to produce. Also, the amount of solute Mn increases and there is a failure of the thermal conductivity. Therefore, the preferable content range of 1.5 to 3.0% by weight. The most preferable content of Mn is 1.6 to 2.8% by weight. [Zn: 0.5 to 2.5% by weight] Zn forms the potential of the anodic fin material to give a sacrificial anodizing effect. If the content is less than 0.5% by weight, its effect is not sufficient, whereas if it is greater than 2.5% by weight, the resistance to self-corrosion of the material deteriorates. In addition, due to the dissolution of Zn, the thermal conductivity fails. Therefore, the preferable content range is 0.5 to 2.5% by weight. The most preferable content of Zn is from 1.0 to 2.0% by weight in range.

[Mg: 0.05% by weight or less] Mg has an effect on brazing. If the content is higher than 0.05% by weight, the brazing is susceptible to being damaged. In particular, when the brazing uses a flow based on fluorine, the fluorine of the flow ingredient (F) and the Mg in the alloy react easily so that MgF2 or other compounds are produced. Due to this, the absolute amount of flow that acts effectively in the brazing time becomes insufficient and brazing defects are easily presented. Therefore, the Mg content as an impurity is limited to not more than 0.05% by weight. With respect to impurity ingredients other than Mg, Cu forms the potential of the cathodic material, so it is preferably limited to not more than 0.2% by weight. Cr, Zr, Ti, and V significantly reduce the thermal conductivity of the material even in small amounts, so that the total content of these elements is preferably limited to no more than 0.20% by weight. Next, the meanings and reasons for limiting the cast conditions of the thin slab, the intermediate annealing conditions, the final cold rolling speed, and the final annealing conditions in the present invention will be explained.

[Thin Slab Casting Conditions] The double-band casting method is a continuous casting method that casts a fusion between rotating bands that face each other in the vertical direction and cooled with water to solidify the melt by cooling from the band and cast surfaces of a slab and continuous extraction and winding of the slab from the opposite sides of the bands. In the present invention, the thickness of the cast slab is preferably 5 to 10 mm. If the thickness is in this range, the solidification velocity at the center of the sheet thickness is also rapid, the structure becomes uniform, and, if the composition is in the range of the present invention, there is little formation of coarse compounds. and, after brazing, a fin material having a large crystalline grain size and excellent properties can be obtained. If the thickness of the thin slab from the double-band casting machine is less than 5 mm, the amount of aluminum passing through the casting machine per unit of time becomes too small and casting becomes difficult. Conversely, if the thickness is more than 10 mm, the sheet can no longer be wound by the roll. Therefore, the thickness of the slab is preferably in the range from 5 to 10 mm. Note that the casting speed at the time of solidification of the melt is preferably 5 to 15 m / min. The solidification is preferably completed in the bands. If the casting speed is less than 5 m / min, casting takes too long and reduces productivity, so it is not preferred. If the casting speed is more than 15 m / min, the aluminum melt can not be supplied fast enough and it is difficult to obtain the predetermined form of a thin slab.

[Primary Intermediate Annealing Conditions] When the strength of the final product is reduced by making the final cold rolling speed 10 to less than 50% (second mode), the retention temperature of the primary intermediate anneal is preferably from 200 to 350 ° C. If the retention temperature of the primary intermediate annealing is less than 200 ° C, a sufficient softening state can not be obtained. If the retention temperature of the primary intermediate annealing is higher than 350 ° C, the solute Mn in the matrix ends up precipitating as a compound based on AI- (Fe-Mn) -If at the time of intermediate annealing at a high temperature, so that the material ends up recrystallizing at the time of the secondary intermediate annealing. If the final cold rolling speed is less than 10 to less than 50%, during the brazing time, the material ends up remaining in the state not yet crystallized and the buckling resistance and erosion resistance fail in the brazing time .

If the final cold rolling speed is higher than 50 to 96%, it is critical to apply the final annealing to keep the strength of the final product low. In this case (third embodiment), a retention temperature of the primary intermediate annealing is preferably from 200 to 450 ° C. If the retention temperature of the primary intermediate anneal is less than 200 ° C, a sufficient softening state can not be obtained. If the retention temperature of the primary intermediate annealing is higher than 350 ° C, the solute Mn in the matrix ends up precipitating as a compound in base AI- (Fe-Mn) - Si at the time of intermediate annealing at a high temperature, although because the final cold rolling speed is high, the cold rolling speed before secondary intermediate annealing is low so that the dislocation density is low and recrystallization does not occur at the time of secondary intermediate annealing. However, if the retention temperature of the primary intermediate annealing is higher than 450 ° C, the solute Mn in the matrix ends up being precipitated in a large quantity and coarse size as a compound based on Al- (Fe-Mn) -Si in the time of intermediate annealing at a high temperature, so that not only is the material recrystallized at the time of secondary intermediate annealing, but also the action in the inhibition of recrystallization in the brazing time becomes weaker, the recrystallized grain size becomes less than 500 μm, and the resistance to buckling and resistance to erosion in brazing time fail.

The retention time of the primary intermediate annealing does not have to be particularly limited, although a range of 1 to 5 hours is preferable. If the retention time of the primary intermediate annealing is less than 1 hour, the temperature of the coil as a whole remains irregular and it may not be possible to obtain a uniform recrystallized structure of the sheet, therefore this is not preferred. If the retention time of the primary intermediate annealing is greater than 5 hours, the solute Mn precipitates progressively. Not only is this disadvantageous in the stable assurance of a recrystallized grain size after brazing of 500 μm or more, but also the treatment takes too much time and the produity fails, so this is not preferred. The speed of the increase in temperature and the rate of cooling at the time of the primary intermediate annealing do not have to be particularly limited, although it is preferable at least 30 ° C / hour. If the rate of temperature increase and the control rate at the time of the primary intermediate annealing is less than 30 ° C / hour, the solute Mn precipitates progressively. This is not only disadvantageous in the stable assurance of a recrystallized grain size after the brazing of 500 μm or more, but also the treatment takes too much time and the produity fails, so this is not preferred. The temperature of the first intermediate annealing in the continuous annealing furnace is preferably 400 to 500 ° C. If it is less than 400 ° C, a sufficient softening state can not be obtained. However, if the retention temperature exceeds 500 ° C, the solute Mn in the matrix ends up precipitating as a coarse compound in base AI- (Fe-Mn) -Si at the time of intermediate annealing at a high temperature, so that the an in the inhibition of recrystallization at the time of secondary intermediate annealing or in the brazing time is weakened, the recrystallized grain size becomes less than 500 μm, and the buckling resistance and erosion resistance fails at the time of brazing. The retention time of the continuous annealing is preferably 5 minutes. If the retention time of the continuous annealing is more than 5 minutes, the solute Mn precipitates progressively. This is not only disadvantageous in the stable assurance of a recrystallized grain size after the brazing of 500 μm or more, but the treatment takes too much time and the produity fails, so it is not preferred. With respect to the increase in temperature and the cooling rate at the time of continuous annealing, the speed of the increase in temperature is preferably at least 100 ° C / min. If the rate of temperature increase at the time of continuous annealing is less than 100 ° C / min, the treatment takes too much time and produity fails, so this is not preferred.

[Secondary Intermediate Annealing Conditions] The retention temperature of the secondary intermediate annealing is preferably from 360 to 450 ° C. If the retention temperature of the secondary intermediate annealing is less than 360 ° C, a sufficient softening state can not be obtained. However, if the retention temperature of the secondary intermediate annealing is higher than 450 ° C, the solute Mn in the matrix ends up being precipitated in a coarse manner as a compound based on AI- (Fe-Mn) -If at the time of annealing intermediate at a high temperature and ends up forming a recrystallized structure, so that the an in the inhibition of the recrystallization in the brazing time is weakened, the recrystallized grain size becomes less than 500 μm, and the buckling resistance and the buckling resistance fail. the resistance to erosion in the brazing time. The retention time of secondary intermediate annealing does not have to be limited in a particular way, although a range of 1 to 5 hours is preferable. If the retention time of the secondary intermediate annealing is less than 1 hour, the temperature of the coil as a whole remains irregular and there is a possibility that a uniform structure in the sheet can not be obtained, so this is not preferred. If the retention time of the secondary intermediate annealing exceeds 5 hours, the solute Mn precipitates progressively. This is not only disadvantageous in securing a recrystallized grain size after the brazing of 500 μm or more, but also the treatment takes too much time and productivity, so this is not preferred. The speed of the temperature increase and the cooling rate of the secondary intermediate annealing do not have to be particularly limited, although it is preferable to be at least 30 ° C / hour. If the rate of increase of temperature and cooling rate at the time of secondary intermediate annealing is less than 30 ° C / hour, the solute Mn precipitates progressively. This is not only disadvantageous in securing a recrystallized grain size after the brazing of 500 μm or more, but also the treatment takes too much time and productivity, so this is not preferred.

[Structure of Fibrous Crystalline Grain] Making the metal structure from a fibrous crystalline grain structure at any stage after the primary intermediate annealing, after the secondary intermediate annealing, or after the final annealing (before brazing) represents making the metallic structure of a structure Fibrous crystalline grain does not contain any crystal grain structure of 200 μm or larger at any stage.

[Final Cold Rolling Speed] The final cold rolling speed is preferably 10 to 96%. If the final cold rolling speed is less than 10%, the accumulated tension energy in the cold rolling is less and the recrystallization is not completed in the process of raising the temperature in the brazing time, so that they fail resistance to buckling and resistance to erosion. If the final cold rolling speed exceeds 96%, the edge cracks at the time of rolling become noticeable, and production fails. If the final annealing is not carried out, if the final cold rolling speed exceeds 50%, the final product will have a too high resistance and it is difficult to obtain a predetermined fin shape at the time of material formation. of fin. On the other hand, if the final cold rolling speed is 50% or more, depending on the composition, the final product is made too high a resistance and it is difficult to obtain a predetermined fin shape at the time of production. Fin formation, although at this time, the different properties deteriorate even when the final cold-rolled sheet is subjected to the final annealing (softening) of a retention temperature of 200 to 400 ° C for 1 to 3 hours. In particular, to fin material obtained through primary intermediate annealing of a sheet by a continuous annealing furnace, then the final cold rolling, and then further annealing (softening) at a holding temperature of 200 to 400CC during 1 to 3 hours is excellent in fin formation capacity, is of high strength after brazing, and is excellent in buckling resistance. The fin material of the present invention is cut to the predetermined corrugated widths, alternatively stacked with the flat pipes made of the functional fluid passage material, for example, coated sheet comprising alloy 3003 covered with a brazing material, and brazed together with them to obtain a heat exchanger unit. According to the method of the present invention, at the time of casting a thin slab by means of a double-band casting machine, the compound based on AI- (Fe-Mn) -If it crystallizes uniformly and fine in the slab, while the Mn and Si in the solid solution supersaturated in the Al precipitate from matrix phase to a high density as a phase AI- (Fe-Mn) -Si of submicron level due to heating to high temperature in the brazing time. Due to this, the amount of solute Mn in the matrix, which greatly reduces the thermal conductivity, is reduced, so that the electrical conductivity after brazing becomes superior and an excellent thermal conductivity is exhibited. In addition, for similar reasons, the compound based on AI- (Fe-Mn) -Si finely crystallized and the AI- (Fe-Mn) -Si phase of high density precipitated submicron inhibit the dislocation movement at the moment of the plastic deformation, so that the final sheet after the brazing exhibits a high resistance to tension. In addition, the submicron-AI phase (Fe-Mn) -Si at the brazing time has a strong recrystallization inhibiting action, so that the recrystallized grain size after brazing becomes 500 μm or more, so the buckling resistance is improved. For similar reasons, excellent resistance to erosion is exhibited after brazing. Further, in the present invention, the Mn content is limited to at least 1.5% by weight, so even if the average particle size of the recrystallized grains after the brazing exceeds 3000 μm, the resistance to the tension. In addition, a double-band casting machine is fast at the rate of solidification of the melt, so that the compound based on AI- (Fe-Mn) -If it crystallizes on a thin slab it becomes uniform and fine. Therefore, in the final fin material, there are no la secondary phase particles of equivalent circle diameters of 5 μm or more derived from coarse crystals and excellent resistance to self-corrosion is exhibited. By casting in this way through the double-band continuous casting method, the compound of AI- (Fe-Mn) - Si in the slab becomes uniform and fine and the precipitate of phase AI- (Fe-Mn) - If submicron level after brazing rises in density. In addition, by making the crystal grain size after brazing 500 μm or more, the strength after brazing, thermal conductivity, buckling resistance, erosion resistance, and resistance to self-corrosion are improved. Simultaneously, by introducing Zn, the potential of the material becomes anodic and the sacrificial anodization effect becomes excellent. Therefore, it is possible to obtain an aluminum alloy fin material for use in heat exchanger having excellent durability.

EXAMPLES Next, the examples of the present invention will be explained in comparison with the comparative examples. Both in the examples of the invention and in the comparative examples, the alloys of the compositions of Alloys Nos. 1 to 12 shown in Table 1 were melted, operated through ceramic filters and poured into casting molds of double band for casting. continuously slabs of a thickness of 7 mm at a casting speed of 8 m / min. The cooling rates of the fusions at the time of solidification were 50 ° C / sec. The thin slabs were cold rolled to the sheet thicknesses shown in Tables 2 to 4 (l / AI sheet thickness). After this, the samples were inserted into a metal annealer, the temperature was increased at a rate of temperature increase of 50 ° C / hr, they were maintained at the temperatures shown in Tables 2 to 4 for 2 hours, cooled then at cooling rates of 50 ° C / hr up to 100 ° C or the samples were kept at 450 ° C in a saline bath for 15 seconds, then extinguished in water as primary intermediate annealing. Next, the samples were cold rolled to the sheet thicknesses shown in Tables 2 to 4 (I / A2 sheet thickness), then inserted into a metal annealer, the temperature was raised at a rate of temperature increase 50 ° C / hr, maintained at the temperatures shown in Tables 2 to 4, then cooled at cooling speeds of 50 ° C / hr to 100 ° C as secondary intermediate annealing. The samples were then cold rolled at the final cold rolling speeds shown in Tables 2 to 4 to obtain fin materials of 60 μm thickness. For parts of these samples, the samples were further inserted into a metal annealer, the temperature was raised at a rate of temperature increase of 50 ° C / hr, maintained at the temperatures shown in Table 4 for 2 hr, cooled then at a cooling rate of 50 ° C / hr at 100 ° C as final annealing.

[Picture 1] [Table 2] Table 2 Production Conditions (Composition Study) [Table 3] Table 3. Production Conditions (Study of 2nd Conditions l / A) [Table 4) Table 4. Production Conditions (Study of Final Annealing Conditions) As comparative examples, the alloys of the compositions of Alloys Nos. 13 and 14 shown in Table 1 were melted, cast through ordinary DC casting (thickness 500 mm, cooling rate at the time of solidification of about 1 ° C). / sec), surface milled, submerged, hot-rolled, cold-rolled (thickness 100 μm), immediately annealed (400 ° Cx2hr), and cold-rolled to obtain fin materials with a thickness of 60 μm. The fin materials obtained from the examples of the invention. and the comparative examples were measured through the following (1) to (4). (1) Stress Resistance of Fin Material Obtained (MPa) (2) Forecast of the brazing temperature, the materials were heated to 600 to 605 ° C for 3.5 min, cooled, then measured for the following aspects: [1] Stress resistance (MPa) [2] Size of crystalline grain (μm) parallel to the direction of rolling through the cutting method after the surface electrolytic polishing to present the crystal grain structure by means of the Barker method [3] Natural potential (mV) after immersion in 5% saline after 60 minutes using silver-silver chloride electrode as the reference electrode [4] Corrosion current density (μA / cm2) found by cathode polarization performed in 5% saline solution at a rate of potential sweep of 20 mV / min using a silver-silver chloride electrode as the reference electrode. [5] Conductivity [% IACS] by means of the conductivity test method described in JIS-H0505 (3) Amount of buckling (mm) using the projection length of 50 mm by means of the buckling test method of LWS T 8801 (4) A fin material given a corrugated shape was placed on the surface of a brazed sheet coated with a flux based on non-corrosive fluoride and having a thickness of 0.25 mm (brazed material alloy 4045 coating index of 8% ) (applied load 324 g), heated by a speed and temperature increase of.50 ° C / min to 605 ° C, and kept there for 5 minutes. After cooling, the cross section of the brazing was observed. Finned materials with light erosion at the crystalline grain boundaries were evaluated as good ("G" marks) and fin materials with severe erosion and severe fusion were evaluated as scarce ("P" marks). Note that the corrugated form was as follows: Corrugated form: Height 2.3 mm x width 21 mm x spacing 3.4 mm, 10 peaks The results are shown in Tables 5 to 7.

I Table 5] Table 5 Composition and Properties of Fin Materials (Composition Study) M -J [Table 6] Table 6. Composition and Properties of Fin Materials (Study of Second Conditions l / A) 00 [Table 7] Table 7. Composition and Properties of Fin Materials (Study of Final Annealing Conditions) CD From the results of Table 5, it was learned that the fin materials according to the present invention (Fin Material Nos. 1 to 5) were excellent in the tensile strength after brazing, erosion resistance, resistance to buckling, sacrificial anodizing effect, and resistance to self-corrosion. Fin Material No. 6 of the comparative example had a low Mn content and low tensile strength after brazing. Fin Material No. 7 of the comparative example had a high Mn content, had giant crystals formed at the time of casting, cracked during cold rolling, and did not provide a fin material. Fin Material No. 8 of the comparative example had low Si content and had low tensile strength after brazing. Fin Material No. 9 of the comparative example had a high Si content and lower erosion resistance. Fin Material No. 10 of the comparative example had a high Fe content, had giant crystals formed at the time of casting, cracked during cold rolling and could not provide a fin material. Fin Material No. 11 of the comparative example had a low Zn content, natural cathodic potential and lower sacrificial anodization effect. Fin Material No. 12 of the comparative example had a high Zn content, lower in self-corrosion resistance, and lower in erosion resistance as well. The low Mn content of the Fin Material No. 13 of the comparative example and the low Si content, Mn of the Fin Material No. 14 of the comparative example obtained through ordinary DC casting (thickness of 500 mm, cooling rate at the time of solidification of approximately 1 ° C / sec), surface grinding, immersion, hot rolling, cold rolling (thickness 100 μm), intermediate annealing (400 ° Cx2hr), and cold rolling had low resistance to After brazing, they had small crystalline grain sizes after brazing, and were inferior in buckling strength and erosion resistance. From the results of Table 6, it was learned that the fin materials according to the present invention (Fin Material Nos. 1, 15, and 16) had tensile strengths prior to brazing of no more than 240 MPa, They had excellent formability and were excellent at tensile strength after brazing, erosion resistance, and buckling resistance. Fin Material No. 17 of the comparative example had a final cold rolling speed of 60%, so they had a high tensile strength before brazing and lower in forming capacity. Fin Material Nos. 18 and 19 of the comparative examples had high temperatures of primary intermediate annealing, so that they had structures after brazing that did not recrystallize and were inferior in buckling resistance and erosion resistance. Fin Material No. 20 of the comparative example had a final cold rolling speed of 60%, so it had a high tensile strength before brazing and was inferior in erosion resistance. Fin Material Nos. 21 and 22 of the comparative example had low temperatures of secondary intermediate annealing, so it had high tensile strength before brazing and lower in forming capacity. Fin Material Nos. 23 and 25 of the comparative examples had low secondary annealing temperatures, so had high tensile strength before brazing and lower in forming capacity. Fin Material No. 24 of the comparative example had a high intermediate secondary annealing temperature, so that recrystallization ended and it was lower in erosion resistance. From the results in Table 7, it was learned that the fin materials according to the present invention (Fin Material Nos. 26 to 29) had tensile strengths prior to brazing of no more than 240 MPa, were excellent in Training capacity, and were excellent in tensile strength after brazing, erosion resistance, and buckling resistance. Fin Material No. 30 of the comparative example had a high final annealing temperature, so that recrystallization ended and it was lower in erosion resistance. The Fin Material No. 31 of the comparative example had a low temperature of the final annealing, so that it had high tensile strength before brazing and lower in forming capacity.

INDUSTRIAL APPLICABILITY According to the present invention, an aluminum alloy fin material is provided for use in heat exchanger having adequate tensile strength before brazing allowing easy fin formation, which has high strength after brazing as well, and possesses excellent buckling resistance, erosion resistance, resistance to self-corrosion, and sacrificial anodization and a production method thereof.

Claims (5)

1. A high strength aluminum alloy fin material for use in heat exchanger that has high strength and is excellent in thermal conductivity, erosion resistance, buckling resistance, sacrificial anodizing effect, and self-corrosion resistance , characterized in that it contains Si: 0.8 to 1.4% by weight, Fe: 0.15 to 0.7% by weight, Mn: 1.5 to 3.0% by weight, and Zn: 0.5 to 2.5% by weight, limiting Mg as an impurity to 0.05% by weight or less, and having a residual content of ordinary impurities and Al in chemical composition, having a metallic structure before brazing a fibrous crystalline grain structure, a tensile strength before brazing of no more than 240 MPa , a tensile strength after brazing of no more than 150 MPa, and a recrystallized grain size after brazing of 500 μm or more.

2. A method for producing a high strength aluminum alloy fin material for use in a heat exchanger according to claim 1, characterized by casting a melt having the chemical composition according to claim 1 for continuous casting. and rolled in roll of a thin slab having a thickness of 5 to 10 mm by means of a double-band casting machine, cold rolling of this slab to a sheet thickness of 1.0 to 6.0 mm, treatment of this sheet by primary intermediate annealing at 200 to 350 ° C, additional cold-rolling of the sheet to a sheet thickness of 0.05 to 0.4 mm, treating the sheet by secondary intermediate annealing at 360 to 450 ° C, and cold-rolling the sheet by of a final cold rolling speed of 10% to less than 50% up to a final sheet thickness of 40 to 200 μm. A method for producing a high strength aluminum alloy fin material for use in a heat exchanger according to claim 1, characterized by casting a melt having the chemical composition according to claim 1 for casting in a manner continue and wind a thin slab that has a thickness of 5 to 10 mm in a roll by means of a double band casting machine, cold roll this slab to a sheet thickness of 1.0 to 6.0 mm, treat this sheet by annealing primary intermediate at 200 to 450 ° C, further cold-laminate the sheet to a sheet thickness of 0.08 to 2.0 mm, treat the sheet by secondary intermediate annealing at 360 to 450 ° C, cold-laminate the sheet at a rolling speed cold from 50% up to 96% to a final film thickness of 40 to 200 μm, and treat the sheet by means of final annealing at 200 to 400 ° C. 4. A method according to claim 2 or 3, characterized in that the primary intermediate annealing is performed by means of a continuous annealing furnace with a temperature increase rate of 100 ° C / m or more and with a temperature of retention of 400 up to 500 ° C and a retention time of 5 minutes. 5. A method according to any of claims 2 to 4, characterized in that, in the stages subsequent to the primary intermediate annealing, after the secondary intermediate annealing, and after the final annealing, the metal structure is a structure of fibrous crystalline grain.