JP4286432B2 - Method for producing aluminum alloy piping material for heat exchanger - Google Patents

Description

【０００９】
【表３】

【００１０】
【発明の効果】
この様に本発明によれば、自動車用熱交換器のアルミニウム合金配管材としてクラッド材ではなく、単層のベア材であっても、製造時の加工性と優れた耐食性および曲げ加工性の全てを具備した熱交換器配管材が得られ、熱交換器のコストダウンが図れる等、工業的に顕著な効果が得られる。
【図面の簡単な説明】
【図１】自動車用エアコンのシステム説明図である。
【符号の説明】
１ コンデンサー
２ エバポレーター
３ 配管
４ コンプレッサー
５ レシーバー[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an aluminum alloy pipe material having excellent workability and excellent corrosion resistance suitable for pipes of heat exchangers such as automobile air conditioners, oil coolers, and radiators.
[0002]
[Prior art and problems to be solved by the invention]
For example, in an automobile air conditioner, as shown in FIG. 1, a condenser 1 made of an aluminum alloy heat exchanger and an evaporator 2 are connected by an aluminum pipe 3, and a compressor 4 or a receiver 5 that compresses a refrigerant such as Freon is interposed therebetween. It is provided and configured.
The aluminum pipe 3 is formed by extruding a JIS3003 (Al-Mn-based) alloy, JIS1100 (pure Al-based) alloy, or JIS6000-based alloy (Al-Mg-Si based) into a raw pipe, and continuously drawing the raw pipe. The piping material having an outer diameter of 8 to 16 mm (wall thickness of 1 to 2 mm) is used, and the piping material having an outer diameter of 8 to 34 mm of the alloy is also used at the entrance and exit of a radiator or the like. For example, in a JIS 6000 series alloy, Japanese Patent Laid-Open No. 58-110653 discloses that Mg is 0.35 to 1.5 wt%, Si is 0.2 to 0.8 wt%, and Zn is 0.1 to 0.3 wt%. An aluminum alloy excellent in intergranular corrosion resistance and pitting corrosion resistance characterized by containing 0.02 to 0.1 wt% of Sn and 0.15 to 0.4 wt% of Cu is presented. Yes.
However, when the piping is used in an engine room of a car with a poor environment, or when it is used in a hot and humid environment such as Southeast Asia, penetration corrosion may occur. If it occurs, the refrigerant (cooling water) in the piping leaks, the cooling function is lost in the air conditioner, and the engine is burned in the radiator.
For this reason, among the conventional corrosion prevention methods, the method of cladding an Al—Zn alloy on the outer surface of the pipe is the most effective, but it takes time and effort to increase the cost. In addition, the coating method is simple and low-cost, but sufficient effects cannot be obtained, and even recently, even coating tends to be omitted due to the demand for cost reduction.
In addition, since the rust preventive material (inhibitor) is added to the refrigerant | coolant and cooling water which flow through the inside of a pipe, there is almost no corrosion from the inside of a pipe, and corrosion progresses mainly from the outside of a pipe. Therefore, it has been necessary to develop a material having a single layer and better corrosion resistance than a conventional alloy without cladding or painting.
Moreover, it goes without saying that the piping material is required to have good formability and workability from the viewpoint of the bending process or the like when assembling the extrusion process or heat exchanger when manufacturing it. However, conventional piping materials are not necessarily sufficient in that they have all of these corrosion resistance, formability, and workability.
[0003]
[Means for Solving the Problems]
The above object of the present invention has been achieved by the following means.
That is , the present invention relates to 0 . Containing 1 wt% to 0.5 wt% or less of Cu, 0.6 wt% to 0.85 wt% or less of Mn, 0.1 wt% to 0.3 wt% or less of Cr, and Si as an inevitable impurity 0.2 wt% or less, to restrict the Fe below 0.6 wt%, the balance per the to produce a heat exchanger aluminum alloy piping material ing of Al and unavoidable impurities, exceed 330 ° C. the annealing treatment, 450 ° C. The present invention provides a method for producing an aluminum alloy piping material for a heat exchanger , which is heated at the following temperature for 1 to 10 hours and performed at a cooling rate of 100 ° C./hour or more.
[0004]
DETAILED DESCRIPTION OF THE INVENTION
It will be described alloying elements of the aluminum alloy piping material according to the present invention below.
Cu; Cu promotes surface corrosion and suppresses the occurrence of pitting corrosion, and dulls intergranular corrosion sensitivity to improve corrosion resistance. Furthermore, it contributes to strength improvement.
The reason why the content of Cu exceeds 0.1 wt% and is 0.5 wt% or less is that the effect cannot be sufficiently obtained if it is less than 0.1 wt%, and if it exceeds 0.5 wt%, the self-corrosion is deteriorated. Promotes and impedes extrusion processability. The content of Cu is preferably 0.1 to 0.3 wt%.
Mn; Mn combines with Fe to produce an Al ₆ (MnFe) compound, thereby reducing the precipitation of compounds such as Al ₃ Fe and Al ₆ Fe that become the starting point of pitting corrosion as a cathode, and the starting point of pitting corrosion Reduce.
The reason why the Mn content exceeds 0.6 wt% and is 0.85 wt% or less is that the effect and mechanical strength are insufficient when the content is less than 0.6 wt%, and the extrusion processability and molding when the content exceeds 0.85 wt%. This is because the nature is impaired. The Mn content is preferably 0.6 to 0.8 wt%.
Cr; Cr improves pitting corrosion resistance and strength. The reason why the Cr content exceeds 0.1 wt% and is 0.3 wt% or less is that the effect cannot be obtained sufficiently if it is less than 0.1 wt%, and if it exceeds 0.3 wt%, a coarse compound crystallizes out. This is because moldability such as cold drawing processability and product extrusion processability is deteriorated. The content of Cr is preferably 0.1 to 0.2 wt%.
In the present invention, unavoidable Si is defined as 0.2 wt% or less, and Fe is defined as 0.6 wt% or less. The reason is that pitting corrosion is likely to occur regardless of which of the examples of the present invention. The Si content is preferably 0.1 wt% or less, and the Fe content is preferably 0.5 wt% or less.
Incidentally, it is preferable to add a small amount of Ti in the range of 0.15 wt% or less in order to refine the cast structure and improve the workability of the product to the alloy of the present invention. In addition, when it exceeds 0.15 wt%, a coarse compound of Ti is generated, and moldability is lowered.
The manufacturing process of the piping material of this invention can be performed in accordance with a conventional method. This is illustrated as follows.
Aluminum alloy melt casting → homogenization
→ Hot extrusion → Continuous drawing process → Annealing Next, in the present invention, the annealing treatment is performed at a temperature exceeding 330 ° C. and at a temperature of 450 ° C. or lower for 1 to 10 hours, and a cooling rate is performed at 100 ° C./hour or more. The reason for the manufacturing method of the aluminum alloy piping material will be described.
When the heat treatment temperature is lower than 330 ° C., the elongation of the material is lowered and the molding processability such as bending processability is deteriorated. On the other hand, when the annealing temperature exceeds 450 ° C., Al—Mn-based precipitates preferentially precipitate at the grain boundaries, thereby promoting intergranular corrosion and impairing the corrosion resistance. In addition, when the cooling rate is less than 100 ° C./hour, the precipitation of Al—Mn system precipitated at the grain boundary is promoted, the intergranular corrosion is promoted, and the corrosion resistance is impaired.
[0005]
【Example】
Next, the present invention will be described in more detail based on examples .
[0007]
An aluminum alloy having the composition of the present invention shown in Table 2 and a comparative alloy that deviates from the components of the present invention are melt cast to form an ingot having a circular cross section, and this ingot is subjected to homogenization treatment at 610 ° C. for 4 hours. Then, it is cut into a length of 1000 mm to form an extruded billet, which is reheated to 500 ° C. and hot-extruded into a blank tube having an outer diameter of 50 mm, and then subjected to continuous drawing multiple times in the cold to obtain an outer diameter of 8. The tube was finished to 0 mm and a wall thickness of 1.0 mm. Thereafter, artificial aging treatment shown in Table 3 was performed, and the specimen was cooled at a cooling rate shown in Table 3 to obtain a test piece.
After performing a CASS test based on JISH8601 for 400 hours for these specimens, the corrosion products were removed, and the pitting depth was measured using an optical microscope to obtain the maximum pitting depth.
Moreover, the extrusion workability at the time of producing the pipe material was evaluated based on whether it was good or bad by comprehensively judging whether or not the extrusion force, extrusion speed and sufficient shape at the time of extrusion were obtained.
The bending workability was evaluated by the tensile bending (stretch bend) method used for the actual bending process for the raw pipe after drawing and annealing. The bending conditions were a bending radius of 30 mmФ and a bending angle of 60 °. It was judged that the tube without abnormality after bending was good, and the tube that was broken or rough was bad.
Table 3 shows the results. It can be seen that the examples of the present invention have excellent corrosion resistance, extrusion workability and bending workability as compared with the comparative examples.
[0008]
[Table 2]

[0009]
[Table 3]

[0010]
【The invention's effect】
As described above, according to the present invention, not only the clad material but the single layer bare material as the aluminum alloy piping material of the automotive heat exchanger, all of the workability at the time of manufacture and the excellent corrosion resistance and bending workability are obtained. The heat exchanger piping material provided with the above can be obtained, and the industrially significant effects can be obtained, such as cost reduction of the heat exchanger.
[Brief description of the drawings]
FIG. 1 is an explanatory diagram of a system for an air conditioner for automobiles.
[Explanation of symbols]
1 Condenser 2 Evaporator 3 Piping 4 Compressor 5 Receiver

Claims (1)

Containing 0.1 wt% to 0.5 wt% or less Cu, 0.6 wt% to 0.85 wt% or less Mn, 0.1 wt% to 0.3 wt% or less Cr, as inevitable impurities Si less 0.2 wt%, to restrict the Fe below 0.6 wt%, the balance per the to produce a heat exchanger aluminum alloy piping material ing of Al and unavoidable impurities, exceed 330 ° C. the annealing process, The manufacturing method of the aluminum alloy piping material for heat exchangers characterized by heating at the temperature of 450 degrees C or less for 1 to 10 hours, and performing a cooling rate on the conditions of 100 degrees C / hour or more.

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