JPS6121296B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to an aluminum alloy for thin plates having excellent formability and corrosion resistance. Conventionally, for example, fins, crowns, aluminum cans, foil containers, etc. for fin/tube heat exchangers were
The material is a thin plate approximately 0.1 to 0.25 mm thick made of soft material such as A1100 series alloy O material or H ₂₂ material.
It is made by subjecting it to various processing such as drawing. Incidentally, recently, there has been an increasing demand for thinner aluminum alloy plates used as materials in order to reduce costs due to the soaring price of aluminum ingots or from the viewpoint of energy conservation. However, when an aluminum alloy plate that is thinner than the conventional one is drawn, defects such as cracks may occur. Therefore, a method of using ironing instead of drawing was considered, but defects such as cracks occur even when ironing is applied to a thin sheet material made of soft A1100 alloy and thinner than conventional ones. this is,
This is because the formability of A1100 alloy is poor, and when the strength of A1100 alloy is increased, its elongation becomes extremely small. This will be explained using fins for a fin/tube type heat exchanger as an example. Finn 1 has the first
As shown in the figure, a collar 3 is formed on the periphery of a hole 2 made for inserting the heat exchanger in order to improve the adhesion between the fin 1 and the heat exchange tube.
A flare 4 is formed at the tip. Such a fin 1 is a thin plate material with a thickness of about 0.12 to 0.22 mm made of a soft material (tensile strength of 9 to ₁₄ Kg/mm ² and elongation of about 10% or more) such as A1100 alloy O material or H 22 material. As shown in Fig. 2, one or more drawing process (expansion process), hole punching process, hole expanding process,
It is made using the so-called bur oak method, which includes a flaring process.
By the way, in order to reduce costs or make the heat exchanger more compact, it is necessary to make the material thinner, but with the bur oak method mentioned above, if the material is thinner than the conventional method, it may cause defects such as cracks. may occur. Therefore, as shown in Figure 3, a method was considered in which an ironing process is performed after the flange process, but even with this method, the material made of soft material A1100 alloy and thinner than conventional ones would not crack. Such defects may occur. This is because the soft material of A1100 alloy has high elongation, but insufficient strength and poor formability. In other words, in order to prevent cracks, etc., the tensile strength must be approximately 15 kg/mm ² or more and the elongation must be approximately 5% or more, but even if A1100 alloy is tempered, the tensile strength will not increase. If the elongation is 15 Kg/mm ² or more, the elongation will be less than 5%, and if the elongation is 5% or more, the tensile strength will be less than 15 Kg/mm ² . The present invention was made in view of the above circumstances, and an object of the present invention is to provide an aluminum alloy for thin plates that satisfies required values for both tensile strength and elongation, has excellent formability, and has excellent corrosion resistance. . In this specification, the term "sheet" includes foil. The aluminum alloy for thin plates with excellent formability and corrosion resistance according to this invention has 0.5wt% magnesium.
more than 1.0wt% and magnesium
Contains 0.05-1.0wt%, and further contains iron and silicon.
Within the range of 0.05 to 0.6 wt% and 0.05 to 0.6 wt% of silicon, and the ratio of these contents ([Fe]/[Si]) (however, [Fe] and [Si] are the iron and silicon contents ( wt%) is 0.5 to 1.5, with the remainder consisting of aluminum and inevitable impurities. In the above, by incorporating both magnesium and manganese into aluminum,
It has the property of increasing the strength and elongation of aluminum alloys for thin plates and improving corrosion resistance. In particular, aluminum alloys for thin plates are
Manganese is added to materials for making fins for tube-type heat exchangers because manganese precipitates finely during heat treatments such as homogenization, preheating, hot rolling, and annealing before processing. It significantly improves workability and enables faster ironing processes. Furthermore, when magnesium coexists with manganese, fine precipitation of manganese during heat treatment is further promoted, and ironing workability is further improved. Manganese content is 0.05wt
If it is less than %, the above effect cannot be obtained. moreover,
If the manganese content exceeds 1.0wt%, a large amount of coarse crystallized substances will be generated during casting, impairing formability, especially when used as a material for fins for fin-tube heat exchangers and processed. , the interface between coarse crystallized substances becomes the starting point of cracks, causing cracks to occur in the flare. In addition, the content of magnesium
If it is less than 0.5wt%, the above effect will be small, and 1.0wt%
If it exceeds this, work hardening becomes too large and cracks occur during processing. Therefore, the magnesium content should be selected in a range of more than 0.5 wt% and 1.0 wt% or less, and the manganese content should be selected in a range of 0.05 to 1.0 wt%. Iron has the property of making the crystal grains of the aluminum alloy for thin sheets finer and improving its strength and elongation by incorporating it into aluminum. In particular, it has the effect of preventing the material from tearing when it is used as a material for heat exchanger fins and subjected to ironing after flange molding. However, if the iron content is less than 0.05 wt%, the above effects cannot be obtained, and if it exceeds 0.6 wt%, the corrosion resistance decreases, so the iron content should be selected within the range of 0.05 to 0.6 wt%. When silicon is included in aluminum, it has the property of improving the ductility of the alloy. In particular, when this alloy is used as a material for making heat exchanger fins, it prevents cracking during ironing. can do. In addition, silicon promotes the fine precipitation of manganese,
It also has the property of improving ironing workability. However, if the silicon content is less than 0.05 wt%, the above effects cannot be obtained, and if it exceeds 0.6 wt%, corrosion resistance will decrease, so the silicon content should be selected within the range of 0.05 to 0.6 wt%. . In general, the ratio of iron to silicon content ([Fe]/[Si]) is within the range of 0.5 to 1.5,
Preferably, when it is within the range of 0.8 to 1.2, the formability of the aluminum alloy can be improved. When this alloy is used as a material for making fins for fin-tube heat exchangers, it is possible to eliminate the directionality of the collar height and prevent the occurrence of cracks during ironing and flaring. However, this effect cannot be obtained outside the above range. Furthermore, the alloy of the present invention may contain impurities that are unavoidable during manufacturing as long as they do not change its properties, but especially in the case of copper, the content is 0.15wt%.
If the content exceeds 0.15% by weight, the corrosion resistance decreases, so it is preferable that the content of copper among impurities is 0.15wt% or less. Furthermore, it is preferable to include titanium and boron among the impurities because they have the effect of making the casting structure finer, but if the titanium content exceeds 0.19wt% and the boron content exceeds 0.15%, the alloy of this invention The content of each component is preferably less than the above value because the properties will change. Next, examples of the present invention will be shown together with comparative examples. Example 1 Ingots of six types of aluminum alloys shown in Table 1 were hot rolled at 500°C to a thickness of 4 mm, and then cold rolled to a thickness of 0.1 mm. Then, temper annealing was performed to obtain the tensile properties shown in Table 1 in the final annealing. Then, these materials are made into a hole with a diameter of 10 mm.
Ironing was performed using an ironing die with a fin collar height of 1.6 mm, and the formability was examined. The results are summarized in Table 1.

[Table] As is clear from Table 1 above, the aluminum alloy of the present invention has both high tensile strength and elongation and excellent formability, and no cracking occurred even when ironing was performed. In particular, in the case of No. 4, no cracking occurred even when ironing was performed at high speed. In contrast, with conventional alloys, when the tensile strength is increased, the elongation decreases, and when the elongation is increased, the tensile strength decreases, and cracks occur when ironing is applied. Example 2 Among the six types of alloys shown in Table 1, No. 2, No. 4 and
After alloy No. 6 was cast into an ingot, it was made into a thin plate with a thickness of 0.1 mm in the same manner as in Example 1 above. Next, the corrosion resistance was examined when immersed in tap water, salt water spray, sea water, and exposed to the atmosphere. The results are shown in Table 2.

【table】

[Table] As is clear from Table 2 above, the aluminum alloy of the present invention is superior in corrosion resistance to conventional alloys.

[Brief explanation of the drawing]

Figure 1 is a cross-sectional view of a fin for a fin-tube heat exchanger, Figures 2 and 3 show the fin processing method, Figure 2 is a cross-sectional view showing the process of the bur oak method, and Figure 3 is a cross-sectional view of the fin for a fin-tube heat exchanger. It is a sectional view showing a process of a method of performing ironing after flange forming.

Claims (1)

[Claims] 1 Magnesium exceeding 0.5wt% and 1.0wt%
Contains 0.05 to 1.0 wt% of iron and manganese, and further contains iron and silicon, 0.05 to 0.6 wt% of iron, silicon
within the range of 0.05 to 0.6 wt% and the ratio of these contents ([Fe]/[Si]) (where [Fe] and [Si] represent the iron and silicon contents (wt%), respectively) An aluminum alloy for thin plates with excellent formability and corrosion resistance, which contains aluminum with a carbon content of 0.5 to 1.5, and the balance is aluminum and unavoidable impurities.