JPH11343532A - Corrosion resistant and high strength aluminum alloy material, its production, tube for heat exchanger made of aluminum alloy and heat exchanger made of aluminum alloy - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a corrosion resistant and high strength aluminum alloy material free from deterioration in corrosion resistance and strengths even in the case of being subjected to brazing and maintaining characteristics obtd. by rapid solidification at the time of producing a high corrosion resistant aluminum alloy for a heat exchanger by a rapid solidifying method. SOLUTION: This invention is the one having a compsn. contg., by weight, 1.0 to 4.0% Mn, 0.1 to 1.0% Cu and at least one or >= two kinds among Ti, Cr and Zr by <=0.3%, and the balance substantial Al, having a supersaturated FCC single phase structure and having 0.05 to 0.5 mm thickness. Preferably, <=0.2% Fe and/or Si is incorporated therein.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an aluminum alloy material having excellent corrosion resistance and excellent strength characteristics, and particularly to an aluminum alloy material which is most suitable as a tube for an aluminum alloy heat exchanger.

[0002]

2. Description of the Related Art Conventionally, heat exchangers for automobiles have been manufactured by a brazing method using an A3003 alloy, which is an Al-Mn alloy, as a refrigerant tube material. In recent years, the thickness of members for reducing the size and weight of heat exchangers has been reduced. The strength of the heat exchanger is maintained at a predetermined level by the thickness of the member. In the conventional A3003 alloy, the reduction in size and weight by reducing the thickness of the plate is reaching its limit from the viewpoint of corrosion resistance and strength.

[0003] Generally, in an aluminum alloy, the strength is increased by adding Mn, Fe, Ti, Cr, Zr, Cu, etc. to the matrix Al, and as the amount of the added element increases, the added element becomes a solid solution and an intermetallic compound. It is known that the strength is remarkably increased due to crystallization, precipitation and the like. However, when an intermetallic compound such as Al-Cu is crystallized and precipitated in the mother phase Al, a potential difference is generated between the mother phase and the intermetallic compound, forming a local galvanic battery and promoting corrosion. It is known.

[0004] Therefore, in order to simultaneously improve corrosion resistance and strength, an appropriate additive element is selected, added in an appropriate amount and uniformly and as much as possible as a solid solution, and in addition, crystallization of an intermetallic compound is performed. And to prevent precipitation. One of the means is a rapid solidification method. The rapid solidification method enables uniform solid solution of alloying elements, formation of supersaturated solid solution and fine dispersion of intermetallic compounds, which have been difficult in the past. In some cases, alloy properties can be significantly improved.

However, the alloy structure produced by the rapid solidification method is in a non-equilibrium state and is unstable with respect to heat, so that it tends to be activated by reheating or the like. Current,
Automotive heat exchangers are manufactured by the brazing method, and the preferred non-equilibrium structure formed by rapid solidification returns to an equilibrium state by thermal activation, so that most of the properties obtained by rapid solidification disappear. there is a possibility. This is because a supersaturated solid solution formed by rapid solidification is thermally decomposed into a low-concentration solid solution and an intermetallic compound, and the rapidly solidified structure is deteriorated due to coarsening of the fine crystal structure.

[0006]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to produce a highly corrosion-resistant aluminum alloy for a heat exchanger by a rapid solidification method without reducing the corrosion resistance and strength even when brazing is performed. An object of the present invention is to provide a corrosion-resistant and high-strength aluminum alloy material which retains excellent characteristics obtained by rapid solidification and a method for producing the same, and a tube for an aluminum alloy heat exchanger and an aluminum alloy heat exchanger using the same. .

[0007]

SUMMARY OF THE INVENTION The present invention relates to a method for preparing M
n 1.0-4.0%, Cu 0.1-1.0%, Ti, C
at least one or more of r and Zr is 0.3
%, The balance being substantially Al, a supersaturated FCC single-phase structure, and a corrosion-resistant and high-strength aluminum alloy material having a thickness of 0.05 to 0.5 mm. The corrosion-resistant and high-strength aluminum alloy material according to the present invention can contain 0.2% or less of Fe and / or Si.

[0008] The present invention also relates to the present invention, wherein
Aluminum containing 4.0%, 0.1 to 1.0% of Cu, 0.3% or less of at least one or more of Ti, Cr, and Zr, with the balance being substantially Al. This is a method for producing a corrosion-resistant and high-strength aluminum alloy material in which a plate material having a thickness of 0.05 to 0.5 mm is obtained by rapidly solidifying an alloy melt at a cooling rate of 10 ³ ° C / sec or more.

Further, the present invention relates to a method for producing a polymer containing Mn of 1.0 to 1.0% by weight.
4.0%, 0.1-1.0% of Cu, 0.3% or less of at least one or more of Ti, Cr and Zr, and the balance substantially consisting of Al, This is a tube for an aluminum alloy heat exchanger made of an aluminum alloy material having a phase structure and a thickness of 0.05 to 0.5 mm.

Further, the present invention relates to a heat treatment made of an aluminum alloy made by integrating a tube plate made of an aluminum alloy brazing sheet clad with a brazing material and an air side fin made of an aluminum alloy fin material by brazing. In the exchanger, the core material of the brazing sheet constituting the tube plate is
Mn 1.0-4.0%, Cu 0.1-1.0%, Ti,
At least one or two or more of Cr and Zr may be used in an amount of 0.1 or more.
3% or less, the balance being substantially composed of Al, a supersaturated FCC single-phase structure having a thickness of 0.05 to 0.5 mm
This is an aluminum alloy heat exchanger using the aluminum alloy material described above.

The reason for limiting the composition of the aluminum alloy material according to the present invention will be described. The aluminum alloy material according to the present invention has an Mn content of 1.0 to 4.0% by weight,
u 0.1 to 1.0%, at least one or more of Ti, Cr and Zr are contained in an amount of 0.3% or less, and the balance is substantially composed of Al. Also, Fe and / or
Alternatively, Si may be contained in an amount of 0.2% or less.

In the present invention, Mn is added as a solid solution in the mother phase Al to improve the strength and to reduce the amount of intermetallic compounds formed by impurities such as Fe and Si which deteriorate the corrosion resistance. However, if it is less than 1.0%, there is no effect, and if it exceeds 4.0%, the Al-Mn intermetallic compound is crystallized even at a cooling rate of 10 ³ ° C / sec or more, thereby deteriorating the corrosion resistance. The precipitation amount of the Mn intermetallic compound remarkably increases, the size of the precipitate increases, and the workability also decreases. Therefore, Mn is 1.0 to 4.0.
%, Desirably 2.0 to 3.5%.

Cu improves the strength by forming a solid solution in the matrix Al. Further, it has the effect of suppressing the occurrence of corrosion by making the electrochemical properties of the tube plate material noble, increasing the potential difference with the brazing material, and forming a potential distribution effective for anticorrosion. If it is less than 0.1%, this effect is insufficient, and if it exceeds 1.0%, Al-C
u intermetallic compound is precipitated and corrosion resistance is reduced,
The melting point is lowered and it melts during brazing. Therefore, Cu is 0.1 to 1.0%, preferably 0.3 to 1.0%.
0.7%.

Ti, Cr and Zr are added as necessary to stabilize the structure against brazing heating.
If it exceeds 0.3%, the precipitation of the intermetallic compound is promoted to lower the corrosion resistance and the workability is lowered. Therefore, when adding, one or two of Ti, Cr and Zr are added.
More than the kind and 0.3% or less. Desirably, 0.1 to
0.25%.

The content of Fe and / or Si is preferably as low as possible because it forms an intermetallic compound and lowers the corrosion resistance, but there is no practical problem if the total amount of Fe and Si is 0.2% or less. .

Next, the structure of the aluminum alloy according to the present invention will be described. The aluminum alloy according to the present invention has a supersaturated FCC (face-centered cubic lattice structure) single-phase structure. In other words, Mn is supersaturated in Al of the FCC structure, which is the parent phase, and has a structure free of crystallized matters and precipitates containing Mn. As described above, since the metal structure is extremely uniform, it is also electrochemically uniform, and since the potential difference in the structure is small, pitting corrosion (corrosion) hardly occurs.
This structure is obtained by mixing an alloy melt having the composition according to the present invention with 1
It can be obtained by quenching at a cooling rate of at least ³ ° C./sec, and has a crystal grain size of 10 to 30 μm, and an average of 20 μm.
It is about. Further, the obtained structure is stable, and hardly any crystallized substance or precipitate is generated even when heated by brazing.

Since the aluminum alloy material according to the present invention has excellent strength, it can be used as a tube for a heat exchanger even when the thickness is 0.05 to 0.5 mm. The conventional A3003 material requires a plate thickness of at least about 0.5 mm from the viewpoint of strength, and it is difficult to further reduce the thickness. However, the aluminum alloy according to the present invention uses A303.
Strength can be improved 1.5 times or more compared to 03 material,
Since the corrosion resistance is more than twice as good as the conventional one, the thickness of the plate material constituting the refrigerant tube is 0.05 to 0.5 m.
m, desirably 0.25 to 0.35 mm, which contributes to the reduction in size and weight of the heat exchanger.

According to the present invention, Mn is 1.0 to 1.0% by weight.
4.0%, 0.1 to 1.0% of Cu, 0.1 to 0.3% of at least one or more of Ti, Cr and Zr
Is rapidly solidified at a cooling rate of 10 ³ ° C / sec or more to increase the solid solution amount of the added element, and to increase the intermetallic compound content. In which the crystallization was suppressed.
A plate having a thickness of 5 mm is directly obtained, and the precipitation of the Al-Mn intermetallic compound is suppressed in the plate even after heating by brazing. The cooling rate during rapid solidification is 3 × 10 ³ ° C./sec.
It is more preferable to make the above.

In the present invention, it is preferable that the molten aluminum alloy is produced by spraying or dropping the molten aluminum alloy from a slit formed at the bottom of a crucible in which the molten aluminum alloy is contained, onto the surface of a cooling rotary roll located immediately below the same.

[0020] The aluminum alloy according to the present invention is used as a heat exchanger tube material, aluminum alloy heat exchanger manufactured by brazing process is excellent in corrosion resistance, salt damage environment as well, SO _X, NO _Even under an environment of exhaust gas such as _X or a combined environment thereof, it is possible to suppress a problem such as refrigerant leakage due to corrosion of the refrigerant tube.

[0021]

Next, the present invention will be described based on an embodiment. Inventive Examples 1 to 8 and Comparative Example 1 shown in Table 1
After adjusting the molten metal having the component composition of ~ 7 in a crucible, a 200 mm diameter water-cooled copper rotating at a tangential speed of 10 m / sec through a slit having a size of 0.8 x 100 mm provided at the bottom of the crucible. Sprayed on the roll surface. The cooling rate is 4 × 10 ° C./sec. At this time, the inner pressure of the crucible was adjusted to 0.1 to 104 atm with purified nitrogen gas, and the amount of molten metal discharged from the slit was controlled to produce a plate material having a plate thickness of 0.5 mm (hereinafter, quenched material). Described).

For comparison, Comparative Examples 8 to 8 shown in Table 1 were used.
Using a molten metal having a component composition of No. 13, hot rolling was performed on an ingot cast with a water-cooled mold, and cold rolling and intermediate annealing were repeated to produce a sheet material having a sheet thickness of 0.5 mm. However, for a sheet material obtained by rolling (hereinafter referred to as a rolled material), Mn
It is known that adding 2% or more of Mn makes it difficult to process and causes intergranular corrosion to lower the corrosion resistance. Therefore, the amount of Mn added was set to 1%.

Observation of the structures of the quenched material of the present invention, the quenched material of the comparative example, and the rolled material revealed that the quenched material of the present invention had a supersaturated FCC single phase structure (average crystal grain size of 20 μm).
m), Comparative Examples 1, 3, and 4 (quenched material) were supersaturated FCC single-phase structures (average crystal grain size: 20 μm), and Comparative Examples 2, 5, 6,
In No. 7 (quenched material), an intermetallic compound having a particle size of about 1 to 3 μm was crystallized, and in a rolled material, an intermetallic compound having a particle size of 5 to 15 μm was crystallized in an FCC matrix structure having an average crystal particle size of 50 μm.

[0024]

[Table 1]

Next, the obtained quenched material and rolled material are partially subjected to a nitrogen atmosphere corresponding to brazing heating conditions for 15 minutes (maximum temperature: 610 ° C., held for 5 minutes).
Table 2 shows the results of the evaluation of the corrosion resistance by performing a corrosion test after heating the sample. For the evaluation of corrosion resistance, a salt spray test (hereinafter, referred to as SST) and a dry / wet cycle corrosion test (hereinafter, referred to as CCT) were applied as corrosion tests. SST is mainly used for evaluation of corrosion resistance under a salt damage environment such as a beach area or a snow melting agent spray area, and CCT is mainly used for evaluation of corrosion resistance under an air pollution environment such as exhaust gas. SST is J
Based on IS Z 2317, CCT repeated spraying of a corrosive liquid and drying / concentration.

In all of Examples 1 to 8 of the present invention, the maximum pitting depth does not increase before and after heating by brazing, and no decrease in corrosion resistance is observed. Furthermore, the maximum pit depth before and after the brazing heating was significantly smaller than in Comparative Examples 1 to 7, and the corrosion resistance was good. Comparative Examples 1 to 4 do not contain Ti, Cr, and Zr, and Comparative Examples 5 to 7 have Ti, Cr, and Zr exceeding 0.3%. Pitting depth is deep. In Comparative Examples 1 to 7, an increase in the maximum pit depth after brazing was observed, and a decrease in corrosion resistance was observed. In Comparative Examples 8 to 13 produced by rolling, there was no increase in the maximum pit depth before and after brazing and no decrease in corrosion resistance was observed, but the maximum pit depth was deeper and the corrosion resistance was inferior to those of the present invention. ing.

Observation of the structures of the quenched material of the example of the present invention and the quenched material of the comparative example after the heating corresponding to the brazing showed that the FCC single-phase structure was maintained in the example of the present invention. In the comparative example, a tendency of coarsening of the crystallized product was confirmed.

[0028]

[Table 2]

Next, the results of the tensile tests performed on the inventive examples 1 to 8 and the comparative examples 1 to 13 to evaluate the strength are shown in Table 3. It was confirmed that both the quenched material of the present invention and the quenched material of the comparative example had a higher tensile strength than the rolled material of the comparative example, and the decrease in strength was small before and after brazing.

[0030]

[Table 3]

Further, Examples 1 to 8 of the present invention and Comparative Examples 1 to 13
Using the brazing material and the fin material shown in Table 4, a corrosion test was performed on a heat exchanger manufactured by brazing. Table 5 shows the results.
The heat exchangers using the alloys of Comparative Examples 1 to 7 of the quenched material and the heat exchangers of the alloys of Comparative Examples 8 to 13 of the rolled material both have the maximum pitting depth of SST and CCT. Is significantly shallow, and the corrosion resistance is good.

[0032]

[Table 4]

[0033]

[Table 5]

From the results shown in Table 3, the aluminum alloy produced by quenching has excellent strength properties as compared with the aluminum alloy produced by rolling, and from the results shown in Table 2, the aluminum alloy produced by quenching was produced. Even if it is an aluminum alloy, it turns out that especially the aluminum alloy concerning this invention is excellent in corrosion resistance compared with the aluminum alloy of a comparative example. Further, from the results shown in Table 5, it is understood that the heat exchanger according to the present invention has better corrosion resistance than the heat exchanger of the comparative example.

[0035]

Industrial Applicability According to the present invention, a corrosion-resistant and high-strength aluminum alloy material which does not cause deterioration in corrosion resistance and strength even when subjected to brazing and retains excellent properties obtained by rapid solidification and its production. A method is obtained. Further, according to the present invention, an aluminum heat exchanger having excellent corrosion resistance and strength characteristics can be manufactured, and further reduction in size and weight can be achieved by thinning the members, thereby promoting resource saving and energy saving.

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Masayuki Hayakawa 1 Nagoya Laboratory, Nagoya-shi, Aichi Prefecture

Claims (5)

[Claims] 1. Mn 1.0-4.0% by weight, Cu
0.1 to 1.0%, containing at least one or more of Ti, Cr, and Zr in an amount of 0.3% or less, the balance being substantially Al, and a supersaturated FCC single-phase structure; A corrosion-resistant and high-strength aluminum alloy material having a thickness of 0.05 to 0.5 mm. 2. The corrosion-resistant and high-strength aluminum alloy material according to claim 1, containing 0.2% or less of Fe and / or Si. 3. Mn 1.0-4.0% by weight, Cu
An aluminum alloy melt containing 0.1 to 1.0%, at least one or more of Ti, Cr, and Zr of 0.3% or less and a balance substantially consisting of Al is cooled. A method for producing a corrosion-resistant and high-strength aluminum alloy material, wherein a plate material having a thickness of 0.05 to 0.5 mm is obtained by rapidly solidifying at a speed of 10 ³ ° C / sec or more. 4. Mn 1.0 to 4.0% by weight, Cu
0.1 to 1.0%, containing at least one or more of Ti, Cr, and Zr in an amount of 0.3% or less, the balance being substantially Al, and a supersaturated FCC single-phase structure; A tube for an aluminum alloy heat exchanger, comprising an aluminum alloy material having a thickness of 0.05 to 0.5 mm. 5. An aluminum alloy heat exchanger in which a tube plate composed of an aluminum alloy brazing sheet clad with a brazing material and an air side fin composed of an aluminum alloy fin material are integrated by brazing. The core material of the brazing sheet constituting the tube plate was Mn 1.0 to 4.0 by weight%.
%, 0.1 to 1.0% of Cu, 0.3% or less of at least one or more of Ti, Cr, and Zr, and the balance is substantially composed of Al. A heat exchanger made of an aluminum alloy, comprising an aluminum alloy material having a thickness of 0.05 to 0.5 mm.