WO2017065460A1 - Aluminum alloy with improved corrosion resistance, method of manufacturing aluminum tube or pipe using alloy, and heat exchanger system using same - Google Patents

Abstract

The present invention relates to an aluminum alloy for a heat exchanger tube or pipe with improved corrosion resistance, and a manufacturing method therefor. The aluminum alloy is based on aluminum and comprises: 0.50 wt% or less of Cu; element X [at least one from among rare earth metals of atomic number 57 (La) to atomic number 71 (Lu), Sc, Nb, and Hf] of which the total amount is 0.005-1.0 wt%; and [0.01-2.0 wt% of Mn, (Si+Mg) < 0.65 wt%, and Zn < 4.0 wt%] or [Si ≥ 0.03 wt%, (Mn+Mg+Zn) < 1.0 wt%, and Al ≥ 98.97 wt%] or [0.25-1.4 wt% of Si, 0.4-1.3 wt% of Mg, Mn ≤ 1.0 wt%, and Zn ≤ 0.25 wt%]. In addition, the aluminum alloy may further comprise: at least one element selected from among Fe, Ti, Zr, Cr, V, Ni, Co, In, B, Pb, Bi, Ca, Be, Ag, Pd, Sb, and Y; and other inevitable impurities. When manufacturing a heat exchanger tube or pipe by using the aluminum alloy, the corrosion resistance and strength are improved.

Description

Aluminum alloy with improved corrosion resistance, manufacturing method of aluminum tube or pipe using the alloy and heat exchanger system using the same

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an aluminum alloy, and more particularly, to an aluminum alloy having improved corrosion resistance by adding special elements such as rare earth elements (X element) to an aluminum alloy, and a method of manufacturing the alloy, in particular aluminum 1XXX and 3XXX for processing. And improved aluminum alloys for the 6XXX series.

In general, aluminum or an aluminum alloy material having good light weight and thermal conductivity is used for heat exchangers such as an evaporator, a condenser, and a pipe. In these heat exchangers, it consists of a condenser tube, fin, head pipe, and various piping of an aluminum alloy extrusion material. These heat exchangers are generally constructed by brazing and joining tubes and fins (generally coated with cladding plates on a fin core material or cladding) in a predetermined structure, and then brazing in a heating furnace in an inert gas atmosphere. Is completed.

       Widely used as a tube or pipe material, Al 1XXX series and Al 3XXX series materials are used, and when more strength is required, Al 6XXX series materials are partially used. In addition, the Al 4XXX series is widely used as a clad material for brazing tubes or pipes to pins and head pipes.

Since the extruded tube or the pipe of the heat exchanger is used as the refrigerant passage tube, when penetration occurs due to corrosion during use, the refrigerant leaks and cannot function as a heat exchanger. For this reason, conventionally, Zn (zinc) is affixed on the surface of an extrusion tube by spraying etc., and Zn is diffused by brazing (brazing). As a result, the Zn diffusion layer formed on the tube surface layer acts as a sacrificial anode to the core portion, thereby suppressing corrosion in the plate thickness direction and extending the corrosion penetration life. In this case, after extruded, the tube requires a process for attaching Zn of a Zn coating (sprayed or the like), resulting in an increase in manufacturing cost.

In particular, from the viewpoint of corrosion resistance of the tube, Japanese Patent Laid-Open No. 11-21649 discloses 0.15 to 0.35% by weight of iron, 0.15% by weight or less of silicon, less than 0.03% by weight of zinc, 0.55% by weight of copper, and 0.02 to 0.05% by weight of zirconium. An aluminum alloy containing 0.003 to 0.010% by weight of titanium, iron / silicon ≧ 2.5, and the remainder of which is inevitably added with aluminum has been proposed.

However, in the alloy of the patent document, copper was added as an additive element in order to secure corrosion resistance of the alloy, but a large amount of copper (0.55% by weight) was added, so that many Al-Cu-based intermetallic compounds were formed, thereby reducing extrusion characteristics. Due to the precipitation of the intermetallic compound, there is a problem that the corrosion potential is lowered in the local region of the base material (material) and thus the corrosion resistance is deteriorated.

In order to improve this, Korean Patent Laid-Open Publication No. 10-2011-0072237 has proposed a method of omitting the Zn spraying process outside the tube by adding Zr and B to an aluminum alloy containing 0.15 to 0.45% of copper. . This document contains the technical idea that due to the addition effect of Zr and B, the crystals of aluminum alloys become finer and corrosion resistance is increased. However, when the copper content is more than 0.1% by weight, copper precipitates at the grain boundary during heat exchanger operation, and as a result, the sensitivity of grain boundary corrosion is increased, resulting in tube grain boundary corrosion, which shortens the corrosion penetration life of the tube. .

       In the above documents, Cu was added as a main element to improve corrosion resistance, but the disadvantages of Cu addition were not sufficiently overcome.

Then, in Korean Patent Laid-Open Publication No. 10-2014-0000406 due to the disadvantage of the addition of Cu to minimize the copper (Cu) to 0.01% or less, 0.50 to 1.0% by weight manganese (Mn) and 0.2% by weight or less Zirconium (Zr) was added 0.05 to 0.15 wt% in the composition of silicon (Si), but the corrosion potential of Cu is sacrificed due to the removal of Cu, and the potential design by contact during assembly of each part of the heat exchanger Given the limitations, it is difficult to adopt in heat exchanger systems.

On the other hand, the rare earth metals of atomic number 57 (La) to 71 (Lu) are currently undergoing extensive research and development because of their beneficial properties, but the development activities are mainly in the field of increasing the corrosion resistance and strength of magnesium (alloy), aluminum alloy for casting. It has been focused on increasing the strength of steel and increasing the corrosion resistance by conversion coating on aluminum alloy surface. (J. Alloys Compd ., 2012, 538 (0): 21., Mater. Des ., 2009, 30 (7): 2372., Mater. Des ., 2010, 31 (Supplement 1): S24., Mater. Sci . Eng ., A , 2012, 532: 606., J. Rare Earths , 2011, 29 (10): 961.)

     Very limited literature has reported the effect of adding up to 0.45% of Ce to AlCuMgAg alloys, which reported that the addition of Ce improves the thermal stability of the phase by forming finer and more dense precipitates. (J. Alloys Compd. 352 (2003) 84.). In addition, the addition of 0.2% Ce in Al-2519 and T87 alloys of Al 2XXX series promotes the deposition of dense and fine phases to increase the room temperature strength of the alloy and the addition of 0.4% Ce enhances the thermal stability at 300 ° C. There is a bar. Journal of Alloys and Compounds 491 (2010) 366371

Most of the above documents on the addition of rare earth metals have been researched and developed on the increase of strength and surface coating of alloys, and have been applied to the 1XXX, 3XXX and 6XXX series, which are widely used as tubes or pipes, and 4XXX series for brazing. It is difficult to find related literatures in which rare earth elements are added directly to the alloy to improve properties such as corrosion resistance.

       However, in very few documents, records can be found for the Al 1XXX series and Al 4XXX series. In Korean Patent Nos. 10-1335680 and 10-1349359, the Al 1XXX series was modified and modified to add up to 0.6% of Sc, Y, MM (misch metal), etc. to increase the strength. By omitting the content of the alloy is difficult to manufacture and there is a problem that the production cost increases. In addition, Korean Patent No. 10-1194970 has added up to 0.5% of Ce, La, and MM to brazing aluminum 4XXX series, but this is a result of approaching the brazing property from the viewpoint of corrosion resistance. There is a problem in that the addition content of the metal is not optimized and thus does not contribute significantly to improving the corrosion resistance.

Therefore, in the present invention, by adding rare earth elements to the aluminum alloys of the 1XXX, 3XXX, 4XXX and 6XXX series for processing to increase the corrosion resistance and strength of the aluminum alloy, to overcome the disadvantages when adding Cu.

An object of the present invention for the above problem, in connection with the aluminum refrigerant tube or tubing of the heat exchanger, to solve the above problems. An object of the present invention is excellent in strength and extrudability, corrosion resistance is improved, even in harsh environments heat exchanger and refrigerant tube or pipe life of the aluminum alloy composition and brazing alloy composition and heat exchanger system using the same to maintain the life of the tube or pipe To provide.

The object of the present invention,

0.005% to 1.00% by weight of X element and 0.50% by weight or less of copper (Cu);

As weight percent Mn 0.01-2.0, Si + Mg <0.65 and Zn <4.0;

The element X is at least one of rare earth metals of atomic number 57 (La) to No. 71 (Lu), scandium (Sc), niobium (Nb) or hafnium (Hf) by an aluminum alloy with improved corrosion resistance Is achieved.

And the object of the present invention,

0.005% to 1.00% by weight of X element and 0.50% by weight or less of copper (Cu);

As weight percent Si ≧ 0.03, (Mn + Mg + Zn) <1.0 and Al ≧ 98.97;

The element X is at least one of rare earth metals of atomic number 57 (La) to No. 71 (Lu), scandium (Sc), niobium (Nb) or hafnium (Hf) by an aluminum alloy with improved corrosion resistance Is achieved.

And the object of the present invention,

0.005% to 1.00% by weight of X element and 0.50% by weight or less of copper (Cu);

Si by weight of 0.25 to 1.4, Mg 0.4 to 1.3, Mn <1.0, Zn <0.25;

The element X is also an aluminum alloy having improved corrosion resistance, characterized in that at least one of rare earth metals of atomic number 57 (La) to 71 (Lu), scandium (Sc), niobium (Nb) or hafnium (Hf). Is achieved.

According to a feature of the invention,

The X element may be in the range of 0.01 to 0.60 wt% or 0.05 to 0.50 wt%.

According to another feature of the invention,

Cu may range from 0.002 to 0.45 weight percent or from 0.02 to 0.45 weight percent.

Another object of the invention is;

0.51% to 5.0% by weight of X element and 0.50% by weight or less of copper (Cu);

Si wt% to 17.0, Mn <0.5, Mg <2.0, Zn <2.0 as weight%;

The element X is brazing with improved corrosion resistance, characterized in that at least one of rare earth metals of atomic number 57 (La) to 71 (Lu), scandium (Sc), niobium (Nb) or hafnium (Hf) Is achieved by the aluminum alloy.

According to another feature of the invention,

The aluminum alloy may further include at least one selected from Fe, Ti, Zr, Cr, V, Ni, Co, In, B, Pb, Bi, Ca, Be, Ag, Pd, Sb, and Y.

Another object of the invention is;

0.005 to 1.0% by weight of an element X containing at least one selected from rare earth metals of atomic number 57 (La) to 71 (Lu), scandium (Sc), niobium (Nb) or hafnium (Hf), and Cu content Less than or equal to 0.50% by weight;

[% By weight of Mn 0.01 to 2.0, (Si + Mg) <0.65 and Zn <4.0] or

[Si% 0.03, (Mn + Mg + Zn) <1.0 and Al ≧ 98.97 as weight percent] or

[Si 0.25-1.4, Mg 0.4-1.3, Mn <1.0 and Zn <0.25 as weight%];

Preparing an aluminum alloy molten metal having a composition of 670 ~ 950 ℃ temperature range;

Casting the molten metal to prepare a base material in the form of a billet or a wire rod;

Heat-treating the base material in a temperature range of 450 to 650 ° C. for 5 to 25 hours;

Extruding or drawing the base material;

It is achieved by a method for producing an aluminum tube or tubing comprising a.

According to a feature of the invention, the X element may be in the range of 0.01 to 0.60% by weight or 0.05 to 0.50% by weight.

According to another feature of the invention,

Cu may range from 0.002 to 0.45 weight percent or from 0.02 to 0.45 weight percent.

According to another feature of the invention,

The base material may further include at least one selected from Fe, Ti, Zr, Cr, V, Ni, Co, In, B, Pb, Bi, Ca, Be, Ag, Pd, Sb and Y.

According to another feature of the invention,

The method for producing the molten alloy is an X metal of an individual element, an X mother alloy of two or more elements (a mother alloy made of an alloy of X elements when the X elements are two or more kinds) or an Al-X mother alloy (aluminum and X elements or aluminum). And the X element in a molten metal in the form of an alloy of an X element).

According to another feature of the invention,

The above X element alloy or Al-X mother alloy is Cu, Mn, Si, Mg, Zn, Fe, Ti, Zr, Cr, V, Ni, Co, In, B, Pb, Bi, Ca, Be , Ag, Pd, Sb and Y may further include one or more selected from the form of a ternary or more multi-base mother alloy.

According to another feature of the invention,

The manufacturing method may be characterized by further performing any one of age hardening heat treatment, zinc coating, chemical coating, resin coating and combinations thereof.

Another object of the present invention,

0.005 to 1.0% by weight of an element X containing at least one selected from rare earth metals of atomic number 57 (La) to 71 (Lu), scandium (Sc), niobium (Nb) or hafnium (Hf), and Cu content Less than or equal to 0.50% by weight;

[% By weight of Mn 0.01 to 2.0, (Si + Mg) <0.65 and Zn <4.0] or

[Si% 0.03, (Mn + Mg + Zn) <1.0 and Al ≧ 98.97 as weight percent] or

[Si 0.25-1.4, Mg 0.4-1.3, Mn <1.0 and Zn <0.25 as weight%];

An aluminum tube or tubing having a composition of is achieved by a heat exchanger system, characterized in that it is coupled to a fin, a header or both having a lower corrosion potential than the tube or tubing.

The heat exchanger system, the atomic number 57 (La) to 71 (Lu) of rare earth metal, scandium (Sc), niobium (Nb) or hafnium (Hf) of X element content of at least one selected from 0.51 ~ 5.0 Wt%, Cu content is 0.50 wt% or less;

Si 4.0-17.0, Mn ≦ 0.5, Mg ≦ 2.0, Zn ≦ 2.0 as weight percent;

An aluminum alloy having a composition of may be used as the brazing alloy to be bonded to the pin, the header or both.

In addition, the tube or tubing and the brazing alloy further added at least one selected from Fe, Ti, Zr, Cr, V, Ni, Co, In, B, Pb, Bi, Ca, Be, Ag, Pd, Sb and Y. It may include.

According to another feature of the invention,

Any one of the above tubes, pipes, fins, headers and combinations thereof may be further subjected to any one of age hardening heat treatment, zinc coating, chemical coating, resin coating, and combinations thereof.

According to the present invention, in an aluminum alloy used for heat exchanger tubes or pipes, by improving the composition by adding a special element (denoted as "element" in the present invention) to improve the corrosion resistance, it is possible to improve the corrosion resistance and strength. This results in simplification and cost reduction of the manufacturing process due to increased component life, elimination of zinc coating and the elimination of additional post-treatment processes.

1 is a conceptual diagram illustrating the improvement of corrosion resistance according to the present invention.

Figure 2 is another conceptual diagram illustrating the principle of improving corrosion resistance according to the present invention.

3 is a photograph of an aluminum alloy tube produced by the present invention.

Hereinafter, an aluminum alloy composition and a manufacturing process thereof according to the present invention will be described 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 embodiments of the present invention and do not represent all of the technical idea of the present invention, various equivalents that may be substituted for them at the time of the present application It should be understood that there may be water and variations.

The corrosion-resistant aluminum alloy (henceforth "aluminum alloy") which concerns on this invention contains element X based on aluminum essentially. As used herein, the term "element" refers to any one or more of rare earth metals of atomic numbers 57 (La) to 71 (Lu), scandium (Sc), niobium (Nb), or hafnium (Hf). It is defined as meaning composed elements.

According to the present invention, in the case of an aluminum alloy for tubes or pipes, element X is contained in the range of 0.005 to 1.0% by weight based on the total weight of the aluminum alloy, and Cu is contained in the range of 0.50% by weight or less. Aluminum alloy compositions for tubes or tubing in the present invention can be classified into three types.

First, in addition to the X element and Cu, Mn 0.01 to 2.0, (Si + Mg) <0.65 and Zn <4.0 as the weight percent. In this case, an alloy of the improved Al 3XXX series in which the X element is added to the commercial Al 3XXX series alloy is added.

<< Note: Throughout this specification and claims, the expression A <4.0 in relation to the content of a particular element (A) means that element A is in the range of 0 <A <4.0. >>

Secondly, in addition to the elements X and Cu, Si ≧ 0.03, (Mn + Mg + Zn) ≦ 1.0 and Al ≧ 98.97 in weight percent. In this case, it becomes an alloy of the improved Al 1XXX series in which the X element according to the present invention is added to the commercial Al 1XXX series.

Third, in addition to the X element and Cu, Si 0.25 ~ 1.4, Mg 0.4 ~ 1.3, Mn <1.0, and Zn <0.25 as the weight%. In this case, the alloy of the improved Al 6XXX series in which the X element is added to the commercial Al 6XXX series alloy is added.

In addition, according to the present invention, in the case of the aluminum alloy for brazing, the X element is increased in content than the above three cases contained in the range of 0.51 to 5.0% by weight relative to the total weight of the aluminum alloy, Cu is also in the range of 0.50% by weight or less The content of Mn, Si, Mg and Zn is in the weight percent of Si 4.0-17.0, Mn ≤ 0.5, Mg ≤ 2.0, Zn ≤ 2.0. In this case, the alloy of the improved Al 4XXX series in which the X element is added to the commercial Al 4XXX series alloy is added.

All of the above cases additionally include alloying elements (Fe, Ti, Zr, Cr, V, Ni, Co, In, B, Pb, Bi, Ca, Be, Ag, Pd, Sb, Y) and inevitable impurities. Can be.

Eventually, the aluminum alloy composition according to the present invention excludes 2XXX series of Al-Cu or Al-Cu-Mg alloys, 5XXXX of Al-Mg alloys, and 7XXX series of Al-Zn-Mg-Cu alloys. Except for the element X according to the present invention, the composition is 1XXX series of pure Al alloys, 3XXX series of Al-Mn alloys, 4XXX series of Al-Si alloys and 6XXX series of Al-Mg-Si alloys. Therefore, the aluminum alloy composition according to the present invention corresponds to an improved aluminum alloy composition in which element X is added to the alloys of the above series.

The effects of Cu, Mn, Mg, Si, and Zn, which are the main alloying elements, on the alloy properties in aluminum alloys are as follows.

The alloying element Cu has a disadvantage in that the solid solution in the matrix (Matrix) increases the strength of the aluminum alloy, but greatly reduces the extrudability compared to Mn. In general, it is known that the addition of Zn lowers the corrosion potential, and the addition of Cu increases the corrosion potential. In the case where Zn and Cu coexist, in particular, when the Zn content is small, the potential raising effect by Cu is predominant. In other words, when the Cu content is large, the potential raising effect by Cu is more preferable than the potential lowering effect by the Zn diffusion layer. When the content is less than 0.12% by weight, the effect of adding copper, such as corrosion resistance, is less likely to occur, and the content is 0.45% by weight. When exceeding, extruding property and corrosion resistance fall simultaneously. The preferred content of Cu in the present invention is 0.50% by weight or less, more preferably in the range of 0.002 to 0.45% by weight or 0.02 to 0.45% by weight. In addition, the preferable content of Zn in this invention is 4.0 weight% or less.

Alloying element Mn increases the strength of the aluminum alloy. If the Mn content is less than 0.5% by weight, the effect of increasing strength is small. Exceeding 1.7% by weight reduces the extrudability. The addition of Mn is significantly smaller in the extrudability, in particular the decrease in the limit extrusion speed, compared with the case where the same amount of Si, Cu or Mg is added. It also has the effect of increasing the corrosion potential of the alloy by precipitating with a fine intermetallic compound of Al ₆ Mn. When it is made of a heat exchanger tube, when the corrosion potential of the heat exchanger tube is increased, the potential difference with the fin can be increased, thereby improving the corrosion resistance. If the content is less than 0.6% by weight, the effect of adding manganese, such as corrosion resistance is less, and when the content exceeds 1.2% by weight, the extrudability is reduced. The preferred content of Mn in the present invention is 2.0% by weight or less of aluminum.

The alloying element Si is precipitated as an Al-Mn-Si-based intermetallic compound to suppress grain growth through interfering grain boundary movement, and to improve the extrudability by reducing the deformation resistance during extrusion. If it is less than 0.05% by weight, the manufacturing cost increases during casting, and if the amount of Si is 0.10% or more, the Al-Mn-Si-based intermetallic compound is formed in the alloy, thereby reducing the Mn solubility in the alloy. This can lead to a drop in corrosion potential. In addition, when the content exceeds 0.2% by weight, the strength of the alloy is increased to reduce the extrudability. In the present invention, the preferred content of Si is 0.65 wt% or less when the composition base of the aluminum alloy is 3XXX series, and 0.25 to 1.40 wt% when the composition base of the aluminum alloy is 6XXX series.

The alloying element Mg increases the strength under the influence of solid solution hardening in the matrix, but decreases the extrudability as the amount is increased. If the amount is more than 2.0%, a high melting point compound is formed due to the flux and the reaction and the like, which tends to significantly reduce the bonding property. In addition, when the content exceeds 3.5% by weight, Mg ₂ Al ₃ is precipitated to increase the susceptibility to grain boundary corrosion and stress corrosion. Therefore, the preferred content of Mg in the present invention is 0.65% by weight or less when the composition base of the aluminum alloy is 3XXX series, 0.40 to 1.30% by weight or less when the composition base of the aluminum alloy is 6XXX series.

On the other hand, in the case of metal, an oxide film is formed on the surface to protect the interior from corrosion, but such an oxide film is peeled off or destroyed, and the corrosion of the material gradually proceeds.

       In the aluminum alloy, when Cu is more than the proper content, precipitates tend to form at the grain boundaries, thereby increasing sensitivity to grain boundary corrosion and local corrosion. The reason for this is that the potential of Cu precipitates is high and the periphery of Cu is lowered to form local corrosion micro-cells.

      Therefore, in order to solve this problem, in the present invention, X metal may be added to the aluminum alloy to improve ductility and adhesion of the oxide film, and to suppress local corrosion effect due to Cu, thereby improving corrosion resistance. In addition, since the X metal has an effect of raising the corrosion potential, it is possible to minimize the addition of Cu or replace Cu for the purpose of increasing the corrosion potential.

At this time, when the element X is added, the following effects are obtained.

The element X changes the microstructure of the oxide film to increase the ductility of the oxide film (oxidation scale) to prevent the separation of the film, and to form a wedge shape inward to the oxide film to increase the adhesion between the matrix and the oxide film (that is, in Figure 1 The adhesion between the crystal grains 7 and the protective oxide film 3 is enhanced). In addition, the vacancy collapse effect prevents the formation of pores and improves chemical bonding between the oxide film and the matrix. That is, by suppressing the formation of pores that can be formed between the oxide film and the base to prevent the space between the oxide film and the base and to form a wedge-shaped oxide film with the base to increase the adhesion of the oxide film.

In addition, the element X reduces the local corrosion cathodic reaction of the copper-containing precipitates precipitated in the matrix, thereby reducing the local corrosion reaction of the surroundings, thereby reducing local corrosion due to Cu. In addition, element X enhances corrosion resistance by reducing components such as Fe and Ni, which are fragile elements of corrosion resistance in molten metal during aluminum production.

In the present invention, in order to prevent the aluminum alloy from becoming susceptible to local corrosion and grain boundary corrosion, excellent corrosion resistance was obtained by adding the X element. At this time, the appropriate amount of element X is preferably in the range of 0.005 to 1.0% by weight, more preferably in the range of 0.01 to 0.60% by weight or 0.05 to 0.50% by weight. However, in the case of 4XXX series for brazing, the base of the aluminum alloy composition is preferably in the range of 0.51 to 5.0% by weight.

That is, as shown in Figure 1, when the content of Cu in the aluminum alloy is high, especially 0.10% by weight or more, the precipitation of Cu in the grain boundary becomes severe, thereby increasing the sensitivity to corrosion. This is because when Cu is precipitated at grain boundaries, the solid solubility (Cu content in the base) of Cu is lowered at the surrounding sites and as a result, the effect of increasing the corrosion potential of Cu is reduced. Therefore, the in-base Cu content around the grain boundary is lower than the in-site Cu content in other parts, resulting in intensive corrosion around the grain boundary and accelerating the grain boundary corrosion or local corrosion.

Therefore, when a small amount of the X element component in the present invention is minimized, the side effects of local corrosion due to Cu can be minimized, and the ductility and adhesion of the oxide film formed at the grain boundaries can be improved to minimize side effects when the Cu content is increased. The corrosion resistance is improved by extending the life of the oxide film even on the alloy surface other than grain boundaries. That is, as shown in FIG. 1, an excellent oxide film is formed at the corrosion site formed at the grain boundary, thereby suppressing the progress of corrosion. Incidentally, the addition of the element X has the effect of increasing the strength and corrosion potential of the aluminum alloy can be used as a substitute for Cu, and the effect of improving the plastic formability of the metal by improving the fluidity of the aluminum alloy, improving the brazing characteristics There is also.

On the other hand, in order to maximize the corrosion resistance of the tube or pipe of the heat exchanger, it is necessary to optimize the corrosion resistance of the neighboring parts to be combined with the tube or the pipe. It is desirable that the corrosion potential of the ash is lower than that of the tube or pipe. This may be achieved through the selection of a suitable alloying material for the pin core member and the header material, and may also be achieved through the control of alloying element contents such as Cu, Mn and Zn.

On the other hand, when joining the heat exchanger tube or tubing into the system, the tube or tubing is brazed to the pin core member or the header member by the cladding material using a brazing process. Since the cladding material contains a large amount of Si of 4% or more, Si diffuses to the fin core, header and tube surface. In this case, Si forms an Al-Mn-Si-based intermetallic compound by combining with Mn present in the matrix to reduce Mn solid solubility in the alloy, thereby lowering the corrosion potential. That is, the corrosion resistance of the surface can be deteriorated.

Therefore, when the X element according to the present invention is added to the cladding material, the X element diffuses and penetrates the tube or the pipe and the pin core or the header surface, thereby increasing the corrosion potential of the surface of these materials to compensate for the effects of Si diffusion penetration. As described above, the corrosion resistance of the tube, fin, and header surface is enhanced due to the increased ductility of the oxide film and the prevention of local corrosion due to Cu. In particular, the corrosion resistance is enhanced at the brazing joint, and the wettability of the clad material is also improved to protect the joint, thereby improving the corrosion resistance of the entire heat exchanger system. At this time, the material of the tube, pipe, header, etc. is improved even when using a common commercial aluminum alloy.

2 is a conceptual diagram when the element X according to the present invention is added to an aluminum alloy for brazing. The X element 11 present in the brazing zone 9 diffuses and penetrates the surfaces of the fin core 13 and the tube 15 to form a diffusion layer 17 to prevent corrosion of the fin and tube surfaces. Strengthen.

In addition, since the cladding material is melted due to the characteristics of the brazing process, the fin core and the header are diffusely bonded to the tube. Thus, when a tube or pipe to which the X element is added according to the present invention and a commercially available cladding material are used, The element X of the present invention present in the surface layer of the pipe is diluted by the diffusion layer to lower corrosion resistance and dislocation. At this time, by adding the X element to the cladding material as in the present invention can be compensated for this.

According to the present invention, the preferred X content of the 4XXX series brazing cladding material is in the range of 0.51 to 5.0% by weight in consideration of the X element that is diffused and lost, and Cu is preferably 0.50% by weight or less. At this time, the composition of the preferred aluminum alloy is in the range of Si 4.0-17.0, Mn ≤ 0.5, Mg ≤ 2.0, Zn ≤ 2.0 by weight. And it may further include additional alloying elements (Fe, Ti, Zr, Cr, V, Ni, Co, In, B, Pb, Bi, Ca, Be, Ag, Pd, Sb, Y) and inevitable impurities. In this case, the alloy of the improved Al 4XXX series in which the X element is added to the commercial Al 4XXX series alloy is added.

On the other hand, in Claim 1 of Patent No. 10-1335680, alloy element Fe 0.05-0.5% by weight, Zr 0.1-0.5% by weight, MM 0.01-0.5% by weight, Sc 0.01-0.2% by weight, Y 0.001-0.01% by weight Manufacture of condenser tube for heat exchanger with improved pressure resistance by selecting two or more materials from the group of alloying elements so that the total amount of alloying elements is 0.6% by weight or less and the rest is dissolved and alloyed with pure aluminum to form aluminum alloy. I am suggesting a method.

This patent document contains the contents of addition of MM (a rare earth alloy) and Sc among the X elements in the present invention, but in order to increase the strength of the aluminum alloy, some of Zr, MM, Sc, Y, etc. are added to pure aluminum. Addition to improve the strength resistance characteristics, and corresponds to the Al composition of 99.4% or more, so it corresponds to the modified alloy of 1XXX series aluminum alloy. In general, 1XXX series aluminum alloy is added with silicon (Si), but the patent document is considered to replace Si with Zr, MM, Sc, Y and the like.

In the above patent document, the main elements Cu, Mn, Si, and Mg in the present invention are not added as an alloying element, and in particular, Si, which is a characteristic of the modified 1XXX series alloy according to the present invention, does not include the present invention. It is also clearly distinguished from ideas. In addition, since the Si content is omitted, it is difficult to manufacture the alloy and there is a problem that the production cost increases significantly. Patent document 10-1349359 of the same applicant is also the same as described above.

       Further, in claim 1 of claim 10, at least one surface of the aluminum alloy plate is 4% to 15% silicon, Ag, Be, Bi, Ce, La, Pb, Pd, Sb, Y or misch metal (misch metal A method of assembling an aluminum alloy plate is disclosed which is coated with a brazing aluminum alloy containing 0.01% to 0.5% of at least one element selected from the group consisting of It is a 4XXX series modified alloy composition, X element is in the range of 0.51 to 1.50% by weight, the composition range is different from the present invention containing Cu, it is also distinguished from the technical idea of increased corrosion resistance.

Recently, studies on adding rare earth metals in the magnesium alloy field have been actively conducted, and in the aluminum alloy field, focusing on coating areas such as the development of conversion coatings in which rare earth elements are applied to the surface of aluminum alloys to improve corrosion resistance. .

Therefore, literatures in which the X element is directly added as an alloying element in addition to the existing commercial aluminum alloys are extremely limited, such as those related to casting aluminum alloys, 2XXX series, 1XXX series, and 4XXX series. In particular, it is judged that there is no literature for the 3XXX and 6XXX series, which is an aluminum alloy for processing, as in the present invention, and in the case of the 1XXX and 4XXX series, the composition range and the principle of technology are differentiated from the present invention. In particular, it is judged that there is no literature applying the correlation with copper (Cu), raising the potential of the base material, increasing the oxide film life, improving the corrosion resistance and increasing the strength.

Next, a method of manufacturing a heat exchanger tube or pipe made of an aluminum alloy according to the present invention will be described.

Method for producing a heat exchanger tube or pipe according to the present invention,

Based on aluminum, the content of X element (at least one of rare earth metal, scandium (Sc), niobium (Nb), or hafnium (Hf)) of atomic number 57 (La) to 71 (Lu) 0.005 to 1.0% by weight, the content of Cu comprises 0.50% by weight or less,

 [Mn 0.01 to 2.0 as weight%, (Si + Mg) <0.65 and Zn <4.0] or [Si% as weight%, (Mn + Mg + Zn) <1.0 and Al ≥ 98.97] or [Si as weight% 0.25-1.4, Mg 0.4-1.3, Mn <1.0, and Zn <0.25] are prepared. And the base material may further include at least one selected from Fe, Ti, Zr, Cr, V, Ni, Co, In, B, Pb, Bi, Ca, Be, Ag, Pd, Sb and Y. This may further include inevitable impurities. Then, the prepared base material, that is, the aluminum alloy is formed in a molten state by a general aluminum alloy manufacturing method at a temperature range of 670 to 950 ° C.

 In the method of adding X element, the alloy molten metal may be formed by pouring into a molten metal in the form of an individual X element metal, an X mother alloy of two or more elements, or a master alloy (Al alloy) of Al-X. In addition, in order to increase the convenience of manufacturing, the X-alloy of at least two elements or the Al-X master alloy is made of Cu, Mn, Si, Mg, Zn, Fe, Ti, Zr, Cr, V, Ni, Co, In, B , Pb, Bi, Ca, Be, Ag, Pd, Sb and Y may be added in the form of a ternary or more multi-element master alloy further comprising at least one selected from the inevitable impurities.

The molten metal formed as above is formed into a billet or wire rod by casting or as an ingot as necessary.

The billet or wire rod is then heat-treated for 5 to 25 hours at a temperature range of 450 to 650 ° C., and then the heat-treated billet or wire rod is extruded or drawn to produce a heat exchanger tube or tubing. At this time, it is preferable to extrude the heat exchanger tube in the case of the billet, preheating at a temperature range of 300 to 550 ° C., and starting at a temperature range of 300 to 550 ° C. and ending at 250 to 350 ° C.

If necessary, the product may be manufactured by casting of a non-billet type metal casting method such as cold forging and hot forging. If the material is based on the Al 6XXX series, the aging hardening heat treatment, which is generally applied, may be additionally performed.

The composition (wt%) of the material according to one preferred embodiment in the present invention may be as shown in Table 1 and Table 2.

Alloy composition	Cu	X	Mn	Si + Mg	Zn	Al
Preferred Embodiment	≤0.5	0.005-1.0	0.01 ~ 2.0	<0.65	<4.0	bal.

Alloy composition	Cu	X	Mn	Si + Mg	Zn	Al
Preferred Embodiment	≤0.5	0.005-1.0	≤1.0	0.65-2.7	≤0.25	bal.

Hereinafter, specific examples (1 to 7) and comparative examples (1 to 2) of Table 3 will be described in more detail to help understand the present invention. However, the following examples are merely examples 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 7) and an aluminum alloy (Comparative Examples 1 to 2) were prepared. Table 3 shows the results of the component analysis of these alloy compositions. In Table 3, the composition of these alloys is expressed in weight percent, taking into account that each alloy may contain unavoidable impurities.

The above-described aluminum alloys (Examples 1 to 7 and Comparative Examples 1 to 2) were controlled by controlling the temperature of the molten alloy at a temperature range of 670 to 950 ° C. during casting of the alloy, and heat-treating the same after manufacturing them into billets. Thereafter, a heat exchanger tube was manufactured through extrusion.

Thereafter, the heat exchanger tube was subjected to heat treatment at a general commonly used brazing treatment temperature and treatment time to reflect the result after the brazing treatment. Conventional brazing process temperature and treatment time is from 580 ~ 650 ℃, minutes to several ten minutes in the present invention was carried out 10 minutes heat treatment at 600 ℃.

In order to evaluate the corrosion resistance characteristics of the heat exchanger tube thus manufactured, SWAAT evaluation according to ASTM standard was performed and the results are shown in Table 3. SWAAT evaluation was performed in accordance with ASTM standard G85 test by adding Glacial Acetic acid to 4.2% by weight of NaCl solution to maintain a pH of 2.8 to 3.0 to spray at 0.07MPa pressure under a temperature of 49 ℃. At this time, the spray amount was maintained at 1-2 ml / hr.

	Cu	X	Mn	Fe	Si	Zn	Mg, Cr, Ti	Al	SWAAT Leak Time (hr)
Example
One	0.30	Ce 0.02	0.50	0.25	0.15	0.10	0.15max	bal.	780
2	0.30	Ce 0.10	0.50	0.25	0.15	0.10	0.15max	bal.	930
3	0.30	Ce 0.30	0.50	0.25	0.15	0.10	0.15max	bal.	880
4	0.30	Hf 0.30	0.50	0.25	0.15	0.05	0.15max	bal.	860
5	0.30	Nb 0.30	0.50	0.25	0.15	0.05	0.15max	bal.	840
6	0.30	La 0.50	0.50	0.25	0.15	0.05	0.15max	bal.	900
7	0.30	Sc 0.30	0.50	0.25	0.15	0.05	0.15max	bal.	860
8	0.05	La 0.35	-	0.25	0.15	-	0.15max	bal.	750
9	0.30	La 0.80	0.05	0.25	0.60	0.05	Mg 1.00	bal.	730
Comparative example
One	0.30	-	0.50	0.25	0.15	0.10	0.15max	bal.	480
2	0.12	-	1.20	0.25	0.40	0.10	0.15max	bal.	350
3	0.05	-	-	0.25	0.15	-	0.15max	bal.	360
4	0.30	-	0.05	0.25	0.60	0.05	Mg 1.00	bal.	340

As can be seen through Table 3, it can be seen that Examples 1 to 9 show very excellent performance compared to Comparative Examples 1 to 4.

In addition, Table 4 shows examples and comparative examples according to the present invention for the brazing aluminum alloy. When Al 3003 is used as the heat exchanger component tube, fin core and header, it shows the effect of adding X and Cu to the clad material. That is, the addition of element X improves the corrosion resistance, and the addition of Cu also shows the result of improving the corrosion resistance to some extent.

	Cu	X	Mn	Fe	Si	Zn	Mg, Cr, Ti	Al	SWAAT Leak Time (hr)
Example
One	-	La 1.20	-	-	8.0	-	0.15max	bal.	730
2	0.12	La 1.20	-	-	8.0	-	0.15max	bal.	770
3	0.12	La 3.60	-	-	8.0	-	0.15max	bal.	840
Comparative example
One	-	-	-	-	8.0	-	0.15max	bal.	420
2	0.12	-	-	-	8.0	-	0.15max	bal.	460

The heat exchanger tube or pipe has the advantage of increasing the corrosion resistance because the potential of the heat exchanger tube or pipe can be higher than the fin material or the cladding material. The content tends to be small compared to other sites. This results in lower dislocations compared to other parts of the grain boundary, which results in intensive corrosion of the grain boundary and ultimately penetrates the tube or pipe, thereby losing the function of the heat exchanger.

According to the present invention, as shown in FIG. 1, the addition of the X element increases the corrosion potential of the alloy, prevents local corrosion of copper, and forms a protective ductility film 3 having good ductility at the grain boundary 1. . Since the protective oxide film 3 has good adhesion, corrosion through the grain boundary 1 can be minimized. In other words, even if corrosion occurs, the corrosion site 5 is prevented from penetrating into the crystal grains 7 by the protective oxide film 3.

Therefore, the heat exchanger tube or the pipe using the aluminum alloy according to the present invention can be used for a long time without intergranular corrosion or pitting even under various corrosive environments.

On the other hand, when greater corrosion resistance is required for the tube or pipe in the present invention, the surface of the heat exchanger tube or pipe may be given a sacrificial anode effect by applying a zinc coating (spray, etc.), and additionally, a chemical coating may be applied. It may be. In addition, it is possible to further improve the corrosion resistance of tubes or pipes by optimizing the corrosion potential of heat exchanger tubes or pipes by appropriately selecting fin core members, head materials, and clad materials, which are heat exchanger components other than tubes, to improve macroscopic corrosion resistance. have. At this time, the corrosion potential of the pin and the head is preferably lower than the corrosion potential of the tube or pipe. In addition, the zinc spray or coating treatment, chemical coating treatment and dislocation design technique may be applied at the same time. In addition, by further applying a silicone or resin coating on the surface of the heat exchanger tube according to the present invention can further improve the corrosion resistance, it is also possible to perform an additional age hardening heat treatment if necessary to increase the strength.

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.

 [Description of the code]

1: grain boundary 3: protective oxide film

5: corrosion part 7: grain

9 brazing zone 11 element X

13 fin core 15 tube

17: diffusion layer

Claims (18)

1. 0.005% to 1.00% by weight of X element and 0.50% by weight or less of copper (Cu);

   As weight percent Mn 0.01-2.0, Si + Mg <0.65 and Zn <4.0;

   The element X is an aluminum alloy with improved corrosion resistance, characterized in that at least one of rare earth metal, scandium (Sc), niobium (Nb) or hafnium (Hf) of the atomic number 57 (La) to 71 (Lu).
2. 0.005% to 1.00% by weight of X element and 0.50% by weight or less of copper (Cu);

   As weight percent Si ≧ 0.03, (Mn + Mg + Zn) <1.0 and Al ≧ 98.97;

   The element X is an aluminum alloy with improved corrosion resistance, characterized in that at least one of rare earth metal, scandium (Sc), niobium (Nb) or hafnium (Hf) of the atomic number 57 (La) to 71 (Lu).
3. 0.005% to 1.00% by weight of X element and 0.50% by weight or less of copper (Cu);

   Si by weight of 0.25 to 1.4, Mg 0.4 to 1.3, Mn <1.0, Zn <0.25;

   The element X is an aluminum alloy with improved corrosion resistance, characterized in that at least one of rare earth metal, scandium (Sc), niobium (Nb) or hafnium (Hf) of the atomic number 57 (La) to 71 (Lu).
4. The method according to any one of claims 1 to 3,

   An aluminum alloy with improved corrosion resistance, characterized in that the X element is in the range of 0.01 to 0.60% by weight or 0.05 to 0.50% by weight.
5. The method according to any one of claims 1 to 3,

   An aluminum alloy with improved corrosion resistance, wherein Cu is in the range of 0.002 to 0.45% by weight or 0.02 to 0.45% by weight.
6. 0.51% to 5.0% by weight of X element and 0.50% by weight or less of copper (Cu);

   Si wt% to 17.0, Mn <0.5, Mg <2.0, Zn <2.0 as weight%;

   The element X is an aluminum alloy with improved corrosion resistance, characterized in that at least one of rare earth metal, scandium (Sc), niobium (Nb) or hafnium (Hf) of the atomic number 57 (La) to 71 (Lu).
7. The method according to any one of claims 1, 2, 3 or 6,

   The aluminum alloy further comprises at least one selected from Fe, Ti, Zr, Cr, V, Ni, Co, In, B, Pb, Bi, Ca, Be, Ag, Pd, Sb and Y. Aluminum alloy with improved corrosion resistance.
8. 0.005 to 1.0% by weight of an element X containing at least one selected from rare earth metals of atomic number 57 (La) to 71 (Lu), scandium (Sc), niobium (Nb) or hafnium (Hf), and Cu content Less than or equal to 0.50% by weight;

   [% By weight of Mn 0.01 to 2.0, (Si + Mg) <0.65 and Zn <4.0] or

   [Si% 0.03, (Mn + Mg + Zn) <1.0 and Al ≧ 98.97 as weight percent] or

   [Si 0.25-1.4, Mg 0.4-1.3, Mn <1.0 and Zn <0.25 as weight%];

   Preparing an aluminum alloy molten metal having a composition of 670 ~ 950 ℃ temperature range;

   Casting the molten metal to prepare a base material in the form of a billet or a wire rod;

   Heat-treating the base material in a temperature range of 450 to 650 ° C. for 5 to 25 hours;

   Extruding or drawing the base material;

   Method for producing an aluminum tube or tubing comprising a.
9. The method of claim 8,

   A method for producing an aluminum tube or tubing, characterized in that the X element is in the range of 0.01 to 0.60% by weight or 0.05 to 0.50% by weight.
10. The method of claim 8,

    Cu is 0.002 ~ 0.45% by weight or 0.02 ~ 0.45% by weight of the manufacturing method of the aluminum tube or tubing.
11. The method of claim 8,

    The base material may further include at least one selected from Fe, Ti, Zr, Cr, V, Ni, Co, In, B, Pb, Bi, Ca, Be, Ag, Pd, Sb, and Y. Method of making tubes or tubing.
12. The method of claim 8,

    The method for producing the molten alloy is an X metal of an individual element, an X mother alloy of two or more elements (a mother alloy made of an alloy of X elements when the X elements are two or more kinds) or an Al-X mother alloy (aluminum and X elements or aluminum). And a mother alloy made of an alloy of X elements).
13. The method of claim 12,

    The above X element alloy or Al-X mother alloy is Cu, Mn, Si, Mg, Zn, Fe, Ti, Zr, Cr, V, Ni, Co, In, B, Pb, Bi, Ca, Be , Ag, Pd, Sb and Y further comprising at least one selected from the group consisting of three or more types of multi-alloy master alloy, characterized in that the aluminum tube or pipe manufacturing method.
14. The method of claim 8,

    A method for producing an aluminum tube or pipe further comprising any one of age hardening heat treatment, zinc coating, chemical coating, resin coating, and combinations thereof.
15. 0.005 to 1.0% by weight of an element X containing at least one selected from rare earth metals of atomic number 57 (La) to 71 (Lu), scandium (Sc), niobium (Nb) or hafnium (Hf), and Cu content Less than or equal to 0.50% by weight;

    [% By weight of Mn 0.01 to 2.0, (Si + Mg) <0.65 and Zn <4.0] or

    [Si% 0.03, (Mn + Mg + Zn) <1.0 and Al ≧ 98.97 as weight percent] or

    [Si 0.25-1.4, Mg 0.4-1.3, Mn <1.0 and Zn <0.25 as weight%];

    An aluminum tube or tubing having a composition of heat exchanger system characterized in that it is coupled to a fin, header or both having a lower corrosion potential than the tube or tubing.
16. A rare earth metal of atomic number 57 (La) to 71 (Lu), X element having at least one selected from the group consisting of scandium (Sc), niobium (Nb) or hafnium (Hf) is 0.51 to 5.0% by weight, and the content of Cu Less than or equal to 0.50% by weight;

    Si 4.0-17.0, Mn ≦ 0.5, Mg ≦ 2.0, Zn ≦ 2.0 as weight percent;

    Heat exchanger system, characterized in that bonded to the fin, the header or both using an aluminum alloy having a composition of brazing alloy.
17. The method according to any one of claims 15 to 16,

    The tube or tubing and the brazing alloy further comprises at least one selected from Fe, Ti, Zr, Cr, V, Ni, Co, In, B, Pb, Bi, Ca, Be, Ag, Pd, Sb and Y. Heat exchanger system, characterized in that.
18. The method according to any one of claims 15 to 16,

    Heat treatment system, characterized in that any one of the tube, tubing, fins, headers and combinations thereof further subjected to age hardening heat treatment, zinc coating, chemical coating, resin coating and combinations thereof.

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