KR20110072237A - Aluminum alloy with high corrosion resistance for heat exchanger tube and method for manufactured of heat exchanger tube using thereof - Google Patents

Abstract

PURPOSE: A high corrosion-resistant aluminum alloy for a heat exchanger tube and a method for manufacturing a heat exchanger tube using the same are provided to improve the composition of the aluminum alloy used for the heat exchanger tube so as to improve corrosion resistance without affecting other physical characteristics. CONSTITUTION: A method for manufacturing a heat exchanger tube using a high corrosion-resistant aluminum alloy comprises the next step. A billet or a wire rod is heat-treated in a temperature range of 450~650°C for 10~25 hours to manufacture a heat exchanger tube through direct extrusion or confirm extrusion(S200,S300). The billet or wire rod contains iron of 0.05~0.5 wt.%, silicon of 0.05~0.2 wt.%, manganese of 0.15~0.45 wt.%, one or both of zirconium and boron of 0.05~0.3 wt.%, and aluminum and impurities of the rest amount.

Description

Aluminum alloy with high corrosion resistance for heat exchanger tube and Method for manufactured of heat exchanger tube using

The present invention relates to a highly corrosion-resistant aluminum alloy for a heat exchanger tube and a manufacturing method, and more particularly to an aluminum alloy excellent in corrosion resistance suitable for manufacturing a heat exchanger tube by improving the composition of the aluminum alloy and a method for producing a heat exchanger tube using the same. will be.

Heat exchanger tube is a component used in heat exchangers of automobiles, and is made of aluminum alloy material in consideration of light weight, high strength and thermal conductivity. The heat exchanger tube made of such an aluminum alloy is mounted on the heat exchanger of a transport device including a vehicle to enable high efficiency heat exchange, thereby reducing fuel economy of the transport device.

The heat exchanger tube is a radiator, heater core, oil cooler, and condenser and evaporator using R134a as a refrigerant in automobiles, depending on the application. Used for Since the heat exchanger tube is in direct contact with the refrigerant, an aluminum alloy having excellent corrosion resistance as well as strength and extrusion property is required.

Japanese Patent Laid-Open No. 11-21649 (hereinafter referred to as Patent Document 1) discloses 0.15 to 0.35 wt.% Of iron, 0.15 wt.% Or less of silicon, less than 0.03 wt.% Of zinc, 0.55 wt.% Of copper, and 0.02 of zirconium. We propose an aluminum alloy containing less than 0.05 wt.%, 0.003 to 0.010 wt.% Titanium, iron / silicon ≧ 2.5, and the remainder being impurities which are inevitably added with aluminum.

However, in the aluminum alloy of Patent Document 1, copper and zinc were added as an additive element for securing corrosion resistance of the alloy, but a large amount of copper was added, resulting in the formation of a large number of Al-Cu-based intermetallic compounds, thereby reducing extrusion characteristics. Lowering the corrosion potential of the base material has a problem that the corrosion resistance deteriorates. In addition, in the case of zinc, there is a problem in that hot cracking occurs during casting and stress corrosion cracking causes deterioration of manufacturing characteristics and quality of the product.

The present invention has been made to solve the problems of the prior art as described above, by improving the composition of the aluminum alloy aluminum alloy for heat exchanger tube having excellent extrusion resistance and excellent corrosion resistance under various corrosion environments and heat exchanger tube using the same Its purpose is to provide a method of manufacturing.

Highly corrosion-resistant aluminum alloy for heat exchanger tube according to an aspect of the present invention for achieving the above technical problem, 0.05 to 0.5wt.% Of iron, 0.05 to 0.2wt.% Of silicon, 0.6 to 1.2wt.% Of It is characterized by containing manganese, 0.15 to 0.45 wt.% Of copper, any one or two of 0.05 to 0.3 wt.% Of zirconium or boron, and the remainder being made of aluminum and impurities.

Highly corrosion-resistant aluminum alloy for heat exchanger tube according to another aspect of the present invention for achieving the above technical problem, 0.05 to 0.5wt.% Of iron, 0.05 to 0.2wt.% Of silicon, 0.3 to 0.7wt.% Of It is characterized by containing manganese, 0.3 to 0.7 wt.% Copper, and any one or two of 0.05 to 0.3 wt.% Zirconium or boron, and the remainder being made of aluminum and impurities.

Preferably, the iron content may be 0.05 to 0.3 wt.%.

Preferably, the content of zirconium or boron may be 0.05 to 0.2wt.%.

Method for producing a heat exchanger tube according to an aspect of the present invention for achieving the above technical problem, 0.05 to 0.5wt.% Of iron, 0.05 to 0.2wt.% Of silicon, 0.6 to 1.2wt.% Of manganese And a billet or wire rod containing 0.15 to 0.45 wt.% Copper, containing any one or two of 0.05 to 0.3 wt% zirconium or boron, and the remainder being aluminum and impurities. The heat rod is heat-treated at a temperature in the range of 450 to 650 ° C. for 10 to 25 hours, and then a heat exchanger tube is manufactured by direct extrusion or conform extrusion.

Method for producing a heat exchanger tube according to another aspect of the present invention for achieving the above technical problem, 0.05 to 0.5wt.% Of iron, 0.05 to 0.2wt.% Of silicon, 0.3 to 0.7wt.% Of manganese And a billet or wire rod containing 0.3 to 0.7 wt.% Copper, containing any one or two of 0.05 to 0.3 wt.% Zirconium or boron, and the remainder being aluminum and impurities. The heat rod is heat-treated at a temperature in the range of 450 to 650 ° C. for 10 to 25 hours, and then a heat exchanger tube is manufactured by direct extrusion or conform extrusion.

In the present invention, the injection temperature of the molten alloy for continuous casting for producing the billet or continuous casting rolling for producing the wire rod is a temperature range of 750 to 900 ℃.

In the present invention, a thermal arc spray (TAS) treatment may be further performed on the manufactured heat exchanger tube surface.

Preferably, the heat exchanger tube after the direct extrusion or conform extrusion is controlled to have a grain size of 50 μm or less and a grain size of 70 μm or less after brazing heat treatment.

According to the present invention, by improving the composition of the aluminum alloy used in the heat exchanger tube, the corrosion resistance can be improved without affecting other physical properties, and even if the zinc spraying step is omitted, sufficient corrosion resistance can be secured, thereby simplifying the process. This can increase the manufacturing efficiency and productivity of the product.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. Prior to this, terms or words used in the present specification and claims should not be construed as being limited to the common or dictionary meanings, and the inventors should properly explain the concept of terms in order to best explain their own invention. Based on the principle that can be defined, it should be interpreted as meaning and concept corresponding to the technical idea of the present invention. Therefore, the embodiments described in the specification and the drawings shown in the drawings are only the most preferred embodiment of the present invention and do not represent all of the technical idea of the present invention, various modifications that can be replaced at the time of the present application It should be understood that there may be equivalents and variations.

The highly corrosion-resistant aluminum alloy for heat exchanger tubes according to the invention comprises 0.05 to 0.5 wt.% Of iron, 0.05 to 0.2 wt.% Of silicon, 0.6 to 1.2 wt.% Of manganese, and 0.15 to 0.45 wt.% Of It contains copper, contains 0.05 to 0.3 wt.% Of zirconium or boron, one or two, and the remainder is made of aluminum and unavoidable impurities.

The iron has the characteristics of the symbol Fe, atomic number 26, atomic weight 55.847, specific gravity 7.86, melting point 1540 ° C and boiling point 2750 ° C as a transition element, and iron is present as an Al-Fe intermetallic compound in the matrix. In addition, when manganese, manganese, or silicon coexist, crystallization or precipitation as Al-Mn-Fe intermetallic compound or Al-Mn-Fe-Si intermetallic compound improves the strength after brazing. It acts to suppress grain coarsening.

In the present invention, the iron content is more preferably contained in 0.05 to 0.3wt.% Relative to the total weight of the aluminum alloy. At this time, in the iron content limitation, when the content is less than 0.05wt.%, It is not preferable because the effect of the addition of iron, such as improving the strength is difficult to appear, and when the content exceeds 0.3wt.%, Extrudability and corrosion resistance This is not preferable because it decreases at the same time.

The silicon is a non-metal element and has the characteristics of symbol Si, atomic number 14, atomic weight 28.086, specific gravity 2.32, melting point 1410 ° C and boiling point 2335 ° C. It also has crystallization or precipitation as an Al-Fe-Si intermetallic compound, which hinders grain boundary movement during brazing and suppresses grain growth.

In the present invention, the silicon content is preferably contained in 0.05 to 0.2wt.% Relative to the total weight of the aluminum alloy. At this time, in the silicon content limitation, if the content is less than 0.05wt.%, The quality of the ingot (ingot), which is the base material at the time of casting should be high, which is not preferable because the manufacturing cost increases, the content is 0.2wt When it exceeds.%, It is not preferable because the strength of the alloy is increased and the extrudability is reduced.

The manganese has the characteristics of symbol Mn, atomic number 25, atomic weight 54.9381, specific gravity 7.2 to 7.45, melting point 1244 ° C and boiling point 1962 ° C as a transition element, and manganese is precipitated as a fine intermetallic compound of Al ₆ Mn to cause corrosion potential of the alloy. Noble to improve the strength after brazing, and when silicon coexists, crystallization or precipitation as Al-Mn-Si intermetallic compound improves the strength after brazing. When the heat exchanger tube is made of a heat exchanger tube, the corrosion potential of the heat exchanger tube can be adjusted to increase the potential difference with the fin (fin), thereby making the anticorrosive effect of the fin more effective, thereby improving external corrosion resistance.

In the present invention, the content of manganese is preferably included in 0.6 to 1.2wt.% Relative to the total weight of the aluminum alloy. At this time, in the content of manganese, when the content is less than 0.6wt.%, It is not preferable because the effect of adding manganese, such as corrosion resistance is difficult to appear, and when the content exceeds 1.2wt.%, The extrudability is reduced. Because it is not desirable.

The copper has a characteristic of symbol Cu, atomic number 29, atomic weight 63.546, specific gravity 8.92, melting point 1084.5 ° C and boiling point 2595 ° C as a transition element, and copper is dissolved in a matrix to improve strength after brazing, and a heat exchanger tube When it is made of, the corrosion potential of the heat exchanger tube is made to be valuable, thereby improving the corrosion resistance.

In the present invention, the copper content is preferably included in 0.15 to 0.45wt.% Relative to the total weight of the aluminum alloy. At this time, in the limited content of copper, when the content is less than 0.12wt.%, The effect of adding copper, such as corrosion resistance, is difficult to appear, and it is not preferable. It is not preferable because it is lowered.

Alternatively, the content of manganese may be adjusted to 0.3 to 0.7 wt.%. In this case, in order to compensate for the decrease in the content of manganese, it is preferable to adjust the content of copper together to 0.3 to 0.7 wt.%. This is to improve the workability of the continuous casting rolling process by lowering the manganese content because the workability may worsen due to cracking during continuous casting rolling when the manganese content is high, and the corrosion resistance is lowered by controlling the copper content. This is because it can be supplemented by the crystallization or precipitation of the -Mn-Cu intermetallic compound.

The zirconium has the characteristics of the symbol Zr, atomic number 40, atomic weight 91.22, specific gravity 6.51, melting point 1,852 ℃ and boiling point 3578 ℃ as a transition element, the boron is a non-metal element symbol B, atomic number 5, atomic weight 10.811, specific gravity 1.73 ( Amorphous), melting point 2300 ℃ and boiling point 2550 ℃, and when the zirconium and boron when added to the aluminum alloy has a similar effect to each other, one or two of zirconium or boron is added. Zirconium and boron improve the extrusion properties by reducing the deformation resistance of the extrusion process and at the same time, suppress the grain coarsening after brazing, thereby improving the strength.

In the present invention, the content of the zirconium or boron is more preferably contained in 0.05 to 0.2wt.% Relative to the total weight of the aluminum alloy. At this time, in the content limitation of zirconium or boron, when the content is less than 0.05wt.%, It is not preferable because the effect of adding zirconium or boron such as strength is not preferable, and when the content exceeds 0.2wt.% It is not preferable because the effect is insignificant compared to the cost increase due to the increase in the content of zirconium or boron, such as reducing the extrudability and formability.

A method of manufacturing a heat exchanger tube made of an aluminum alloy according to the present invention as described above will be described with reference to FIG. 1.

1 is a flowchart illustrating a method for manufacturing a heat exchanger tube according to the present invention.

Method for producing a heat exchanger tube according to the invention, in step (S100), 0.05 to 0.5wt.% Of iron, 0.05 to 0.2wt.% Of silicon, 0.6 to 1.2wt.% Of manganese, 0.15 to An aluminum alloy containing 0.45 wt.% Copper, containing any one or two of 0.05 to 0.3 wt.% Zirconium or boron, and the remainder being aluminum and unavoidable impurities. It is inject | poured in the state of a molten metal in the range, and forms the billet by continuous casting or the wire rod by continuous casting rolling. At this time, in the case of a wire rod, it has a diameter of 8.0-15 mmΦ.

In the present invention, the iron content in the composition of the aluminum alloy may be 0.05 to 0.3wt.%, And the content of zirconium or boron may be 0.05 to 0.2wt.%. Alternatively, the content of manganese may be adjusted to 0.3 to 0.7 wt.%. In this case, in order to compensate for the decrease in the content of manganese, it is preferable to adjust the content of copper together to 0.3 to 0.7 wt.%.

In the present invention, the injection temperature range of the molten metal is to obtain a solid solution that is an intermetallic compound, that is, a casting having a dense microstructure. When the injection temperature of the molten metal exceeds 900 ° C, there is a problem that the microstructure of the molten metal becomes coarse. In addition, the temperature range of 750 to 900 ℃ is optimal because less than 750 ℃ because of the lack of fluidity of the molten (Mis Run) phenomenon that can not fill the mold space tightly.

In step (S200), the billet or wire rod is heat-treated for 10 to 25 hours in the temperature range of 450 to 650 ℃.

In step S300, the heat-treated billet or wire rod is manufactured by direct extrusion or conform extrusion. At this time, in the case of billets, the heat exchanger tube is extruded at a temperature range of 300 to 500 ° C by preheating at a temperature range of 300 to 500 ° C.

In the present invention, the manufactured heat exchanger tube is controlled to a grain size of 50㎛ or less, in particular, even after brazing heat treatment is controlled to a grain size of 70㎛ or less to have a fine grain structure that does not occur grain coarsening to improve the corrosion resistance .

On the other hand, when the heat exchanger tube manufactured requires extreme corrosion resistance, a thermal arc spray (TAS) treatment may be performed on the surface of the heat exchanger tube to give a sacrificial anode effect.

Hereinafter, the present invention will be described in more detail with reference to preferred examples (1 to 5) and comparative examples (1 to 7) in contrast thereto. However, the following examples are merely illustrative of the present invention, and the scope of the present invention is not limited thereto.

An aluminum alloy according to the present invention (Examples 1 to 5) and an aluminum alloy (Comparative Examples 1 to 7) were prepared. Table 1 shows the results of the component analysis, which shows the composition of these alloys. In Table 1, the compositions of these alloys are expressed in weight percent, taking into account that each alloy may contain unavoidable impurities.

Composition (wt.%) Fe Cu Mn Si Zr B Ti Al Example 1 0.15 0.45 0.60 0.1 0.20 - - Honey. Example 2 0.42 0.39 0.97 0.1 0.20 0.08 - Honey. Example 3 0.45 0.35 1.1 0.1 0.15 0.08 - Honey. Example 4 0.15 0.42 0.70 0.1 0.20 - - Honey. Example 5 0.28 0.40 0.40 0.1 0.15 - - Honey. Comparative Example 1 0.10 0.12 0.05 0.06 - - - Honey. Comparative Example 2 0.22 0.40 - 0.07 0.04 - 0.008 Honey. Comparative Example 3 0.15 0.07 1.03 0.08 - - - Honey. Comparative Example 4 0.17 0.41 0.14 0.08 0.03 - - Honey. Comparative Example 5 0.02 0.5 0.9 0.1 0.13 - - Honey. Comparative Example 6 0.02 0.1 1.2 0.1 0.13 - - Honey. Comparative Example 7 0.13 0.09 0.50 0.1 - - - Honey.

The above-described aluminum alloys (Examples 1 to 5 and Comparative Examples 1 to 7) are manufactured in the form of wire rods by controlling the temperature of the molten alloy at a temperature range of 750 to 900 ° C. during casting of the alloy and through continuous casting rolling (properzi). After heat treatment. Thereafter, heat exchanger tubes were manufactured through conform extrusion.

In order to evaluate the corrosion resistance characteristics of the heat exchanger tube thus manufactured, SWAAT evaluation based on ASTM standard was performed and the results are shown in Table 2. At this time, all the heat exchanger tubes used were subjected to SWAAT evaluation after performing a brazing simulation process (600 ° C. × 10 min).

Extrudability Whether zinc is sprayed SWAAT Leak Time (hr) Example 1 ○ × 900 Example 2 ○ × 860 Example 3 ○ × 840 Example 4 ○ × 900 Example 5 ○ × 880 Comparative Example 1 ○ ○ 400 Comparative Example 2 △ ○ 450 Comparative Example 3 ○ ○ 380 Comparative Example 4 △ ○ 490 Comparative Example 5 △ × 300 Comparative Example 6 △ × 150 Comparative Example 7 △ × 100

The SWAAT evaluation was performed in accordance with ASTM standard G85 to add a glacial Acetic acid to 4.2wt.% NaCl solution to maintain a pH of 2.8 to 3.0 to spray at 0.07MPa pressure at 49 ℃ temperature atmosphere. At this time, the spray amount was maintained at 1 to 2 ml / hr.

As can be seen through Table 2, Examples 1 to 5 has superior performance compared to Comparative Examples 1 to 7 and excellent corrosion resistance characteristics compared to Comparative Examples 1 to 7 without the zinc spray treatment showing excellent extrudability and sacrificial anode effect. It can be seen that. Therefore, the heat exchanger tube using the aluminum alloy according to the present invention can be used for a long time without pitting even under various corrosion environments.

Although the present invention has been described above by means of limited embodiments and drawings, the present invention is not limited thereto and will be described below by the person skilled in the art to which the present invention pertains. Of course, various modifications and variations are possible within the scope of the claims.

The following drawings, which are attached to this specification, illustrate preferred embodiments of the present invention, and together with the detailed description of the present invention serve to further understand the technical idea of the present invention, the present invention includes the matters described in such drawings. It should not be construed as limited to.

1 is a flowchart illustrating a method for manufacturing a heat exchanger tube according to the present invention.

Claims (11)

0.05 to 0.5 wt.% Iron, 0.05 to 0.2 wt.% Silicon, 0.6 to 1.2 wt.% Manganese, 0.15 to 0.45 wt.% Copper, and 0.05 to 0.3 wt.% Zirconium Or boron containing any one or two, and the remainder is made of aluminum and impurities. 0.05 to 0.5 wt.% Of iron, 0.05 to 0.2 wt.% Of silicon, 0.3 to 0.7 wt.% Of manganese, and 0.3 to 0.7 wt.% Of copper, and 0.05 to 0.3 wt.% Of zirconium Or boron containing any one or two, and the remainder is made of aluminum and impurities. The method according to claim 1 or 2, The iron content is highly corrosion-resistant aluminum alloy for heat exchanger tube, characterized in that 0.05 to 0.3wt.%. The method of claim 3, wherein The content of the zirconium or boron is highly corrosion-resistant aluminum alloy for heat exchanger tube, characterized in that 0.05 to 0.2wt.%. 0.05 to 0.5 wt.% Iron, 0.05 to 0.2 wt.% Silicon, 0.6 to 1.2 wt.% Manganese, 0.15 to 0.45 wt.% Copper, and 0.05 to 0.3 wt.% Zirconium Or boron or wire rod containing any one or two of boron, the remainder being heat-treated for 10 to 25 hours in a temperature range of 450 to 650 ° C. Method for producing a heat exchanger tube, characterized in that for producing a heat exchanger tube through direct extrusion or confirm extrusion. 0.05 to 0.5 wt.% Of iron, 0.05 to 0.2 wt.% Of silicon, 0.3 to 0.7 wt.% Of manganese, and 0.3 to 0.7 wt.% Of copper, and 0.05 to 0.3 wt.% Of zirconium Or boron or wire rod containing any one or two of boron, the remainder being heat-treated for 10 to 25 hours in a temperature range of 450 to 650 ° C. Method for producing a heat exchanger tube, characterized in that for producing a heat exchanger tube through direct extrusion or confirm extrusion. The method according to claim 5 or 6, The iron content is a method of producing a heat exchanger tube, characterized in that 0.05 to 0.3wt.%. The method of claim 7, wherein The zirconium or boron content is 0.05 to 0.2 wt.%, Characterized in that the manufacturing method of the heat exchanger tube. The method of claim 8, The injection temperature of the molten alloy during continuous casting for producing the billet or continuous casting rolling for producing the wire rod is a temperature range of 750 to 900 ℃. 10. The method of claim 9, The method of manufacturing a heat exchanger tube, characterized in that for further performing a thermal arc spray (TAS) treatment on the surface of the heat exchanger tube. The method of claim 10, The heat exchanger tube after the direct extrusion or conform extrusion is characterized in that the crystal grain size is controlled to 50㎛ or less, the crystal grain size after brazing heat treatment is controlled to 70㎛ or less.

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