JPH05169133A - Manufacture of aluminum alloy tube for heat exchanger - Google Patents

Abstract

PURPOSE:To provide the manufacturing method for a tube stock being excellent in corrosion resistance, in the method for manufacturing a multi-hole tube stock used as a tube of a heat exchange manufactured by brazing/heating, by a conforming method. CONSTITUTION:At the time of manufacturing an aluminum alloy tube which contains 0.01-1.10wt.% Si, 0.03-0.6wt.% Fe, 0.1-1.0wt.% Cu, and 0.1-1.6wt.% Mn, or also contains <=0.5wt.% Mg, <=0.3wt.% Cr, <=0.3wt.% Zr, and <=0.3wt.% Ti, and consists of the balance Al and inevitable impurities, by a conforming method a heat treatment of <=520 deg.C is executed to an aluminum alloy before executing the conformation.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing an aluminum alloy tube for a heat exchanger, and more specifically, it conforms a multi-hole tube material used as a tube for a heat exchanger manufactured by brazing and heating. A method for producing a tube material having excellent corrosion resistance in a method for producing by a method.

[0002]

2. Description of the Related Art A heat exchanger such as a radiator, for example, FIG.
In the serpentine type condenser shown in Fig. 1, a tubular material (1) extruded into a tubular shape while hot or warm was bent in a meandering shape, and a corrugated fin (2) made of a brazing sheet was attached between the tubular materials (1). It is a thing. In the figure
(3) indicates a connector.

JIS 1100 (Al-0.1
wt% Cu) and JIS3003 alloy (Al-0.15 wt% Cu)
-1.1 wt% Mn) is used for the multi-hole tube, and the fin has JIS 3003 and the purpose of giving it a sacrificial effect.
An alloy containing Zn or the like is used as a core material, and JIS 4045 (A
1-10 wt% Si) and JIS4343 (Al-7.5 wt%
A brazing material such as Si) clad on both sides is used. All of them are assembled by brazing by heating to a temperature near 600 ° C. and brazing. As a brazing method, a vacuum brazing method, a flux brazing method, a Nocolock brazing method using a non-corrosive flux, or the like is performed.

In recent years, multi-hole tubes have been used in addition to those manufactured by hot extrusion and those manufactured by conform method. This conforming method is a method of processing aluminum material wire into a tube material by utilizing heat generation, and its outline is shown in FIG. In other words, it is a method of supplying a wire (6) between the groove of the rotating grooved wheel (4) and the holding metal fitting (5) and pushing it out from the die (7) by the frictional force between the wire and the wheel. This is different from the conventional method of manufacturing a tube material by extruding a billet. The feature of conform is that the intermetallic compound is finely distributed in terms of material, in addition to the low manufacturing cost, and it has characteristics superior to extruded materials in strength and uniformity of structure.

[0005]

However, there is a problem that the tube material is inferior in corrosion resistance to the extruded material due to the conform, and it is strongly desired to solve the problem.

[0006]

As a result of various studies in view of the above, the present invention has developed a method for producing an aluminum alloy tube for a heat exchanger having excellent corrosion resistance by the conform method.

That is, one of the present inventions is that Si 0.01-1.10 wt.
% (Hereinafter wt% is abbreviated as%), Fe 0.03 to 0.6%, Cu
An aluminum alloy tube containing 0.1 to 1.0% and Mn 0.1 to 1.6% and the balance Al and unavoidable impurities,
In manufacturing by the conform method, the aluminum alloy before the conform is subjected to heat treatment at 520 ° C. or higher.

According to another aspect of the present invention, Si 0.01-1.
10%, Fe 0.3 to 0.6%, Cu 0.1 to 1.0%, Mn 0.1
≤ 1.6%, and one or two of Mg 0.5% or less, Cr 0.3% or less, Zr 0.3% or less, Ti 0.3% or less.
In producing an aluminum alloy tube containing at least one kind of material and the balance Al and unavoidable impurities by the conform method, the aluminum alloy tube before the conform is subjected to heat treatment at 520 ° C. or higher. is there.

[0009]

The alloy composition of the tube material in the present invention is as follows: Si 0.01-1.10%, Fe 0.03-0.6%, Cu
0.1 to 1.0% and Mn 0.1 to 1.6%, or further Mg 0.5% or less, Cr 0.3% or less, Zr 0.3% or less, T
i 0.3% or less, 1 type or 2 types or more, and the balance A
is an aluminum alloy consisting of 1 and unavoidable impurities,
The role of each additive element is described below.

Si is donated to improve the strength. That is, the solid solution effect improves the strength, promotes the precipitation of Mn, increases the amount of intermetallic compounds, and improves the strength. Then Si
If the content is less than 0.01%, the above effect is not sufficient,
If it exceeds 1.10%, the diffusion of the brazing becomes large at the time of brazing heating, the brazing property is deteriorated, and further the corrosion resistance of the tube is deteriorated. Therefore, Si is 0.01% or more,
Although it is set to 1.10% or less, particularly stable characteristics are exhibited at 0.2 to 0.7%.

Fe forms an intermetallic compound together with Mn and contributes to the improvement of strength. But the amount is 0.03%
If it is less than 0.6%, the effect is not sufficient, and if it exceeds 0.6%, a large amount of coarse precipitates are generated during casting, the recrystallized grain size during brazing heating becomes small, and the brazing property deteriorates.

Cu exists in the alloy in a solid solution state and improves the strength. Further, it has the function of making the electric potential of the tube material noble and improving the corrosion resistance. However, if less than 0.1%, the effect is not sufficient, and if more than 1.0% is added,
The melting point of the alloy lowers and the alloy melts during heating by brazing.

Mn forms an intermetallic compound in the alloy to improve the strength. However, if it is less than 0.1%, the effect is not sufficient, and if it exceeds 1.6%, the formability is lowered and the brazing sheet is cracked during processing such as assembly.

In the tube material of the present invention, Mg
0.5% or less, Cr 0.3% or less, Zr 0.3% or less, Ti
One or more of 0.3% may be added. M
g exists in the alloy as a solid solution state and as a fine precipitation phase of Mg ₂ Si, and improves the strength. However, the amount is 0.
If added in excess of 5%, when brazing using non-corrosive Flux, flux reacts with Mg and brazing becomes impossible. In addition, all the other elements form a fine intermetallic compound and have the function of improving the strength of the alloy. However, if added in excess of 0.3%, the formability is lowered and the brazing sheet is cracked during processing such as assembly.

The above are the components of the tube material in the present invention, but B added for refining the structure of the ingot and Ni and other elements for the purpose of improving the strength are 0.05% or less. It can be added if present.

The present invention has solved the problem that the corrosion resistance is inferior when the tube material of the above alloy is manufactured by a normal conforming process. That is, the aluminum alloy wire before the conform is characterized by being heat-treated at a temperature of 520 ° C. or higher. However, the aluminum alloy wire used for the conventional conform has proper workability in the conform process. For this reason, no more than tempering is considered, and the maximum heating temperature at the time of producing an aluminum alloy wire for conforming is about 450 ° C.

Here, the inventors observed the metallographic structure of the tube material, and in the tube material by the conventional conform method, fine particles of 0.05 μm or less exist inside the tube material, and these particles are heated during brazing. Disturbs the movement of grain boundaries,
Therefore, Si and C, which are harmful to the corrosion resistance at the grain boundaries when the brazing heat is applied,
The inventors have found that u segregates and deteriorates corrosion resistance, and has reached the present invention. That is, if the fine particles are coarsened at the stage of the aluminum alloy wire used for conforming, the particles in the tube after conforming are also coarse, and there is no pinning effect at the time of brazing and the secondary Since recrystallization occurs when the brazing heat is applied and the grain boundary moves, a compound harmful to corrosion resistance does not occur at the grain boundary.

Therefore, in the present invention, in order to sufficiently coarsen the intermetallic compound in the tube formed by conforming, the aluminum alloy wire is heated to 520 ° C. or higher at the stage. Here, at a heating temperature of less than 520 ° C., particles that interfere with secondary recrystallization during brazing heating remain.
Further, the longer the holding time at the temperature of 520 ° C. or more is, the better, but it is usually about 0.5 to 24 hours in consideration of economical efficiency. The upper limit of the heating temperature may be the melting point of the aluminum alloy or lower, but it is usually 620 ° C. or lower.

The above heating may be performed on the aluminum alloy wire immediately before conforming or during the production of the aluminum alloy wire. That is, aluminum alloy wire is manufactured by a casting method such as Properch,
The size suitable for conforming is obtained by processing such as rolling and drawing, but the above heating may be performed after rolling and before rolling and drawing.

[0020]

EXAMPLES The present invention will be described below with reference to examples. Table 1
The aluminum alloy tube material having a composition within the range specified in the present invention shown in Table 2 was prepared by the conform method in the manufacturing process shown in Table 2. That is, the Properci method and the rolling process were combined to obtain an aluminum alloy element wire having a cross-sectional area of about 80 mm ² , which was conformed. Here, the heat treatment was applied to the rolled wire rod or the drawn wire rod, and then conforming was performed. Here, the size of the tube is 16 mm in width, 2 mm in thickness, and 8 holes. The plate thickness of the tube material was 0.4 mm.

The obtained tube material was subjected to 600 in N ₂ gas.
Heating was performed under the condition of ° C x 5 min, and the tube material after heating was subjected to the CASS test for 2000 hours to observe the cross section of the tube. The ones through which the corrosion penetrates are marked with X, the ones exceeding the plate thickness central part are marked with Δ, and those not reaching the plate thickness central part are marked with ◯, and the results are also shown in Table 2.

[0022]

[Table 1]

[0023]

[Table 2]

As is apparent from Table 2, the tube material according to the present invention is superior in corrosion resistance to the tube material according to the conventional conform method despite the conform method. On the other hand, it can be seen that the samples according to the comparative examples in which the heating conditions are deviated have poor corrosion resistance.

[0025]

As described above, according to the present invention, the obtained aluminum alloy tube for a heat exchanger has excellent corrosion resistance despite the conform method and has a remarkable industrial effect.

[Brief description of drawings]

FIG. 1 is a perspective view of a partial cross section showing a serpentine type evaporator.

FIG. 2 is an explanatory diagram illustrating a conform method.

[Explanation of symbols]

 1 Flat tube 2 Fins 3 Connector 4 Wheel with groove 5 Holding bracket 6 Wire 7 Dice

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[Procedure amendment]

[Submission date] February 18, 1993

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] 0019

[Correction method] Change

[Correction content]

The above heating may be performed on the aluminum alloy wire immediately before conforming or during the production of the aluminum alloy wire. That is, aluminum alloy wire is manufactured by a casting method such as Properch,
Although the size suitable for conforming is obtained by processing such as rolling and drawing, the above heating may be performed after rolling and before rolling and drawing. Although the conform tube according to the method of the present invention is manufactured as described above, the surface of the conform tube may be sprayed with Zn or plated after conforming. Zn on the surface of such a tube has an effect of improving the external corrosion resistance of the tube, which is a commonly used treatment, and does not impair the corrosion resistance effect improved by the present invention. Furthermore, even if an Al-Si alloy is used as a braze and is formed on the surface of the tube by a method such as thermal spraying or plating, the effect of the present invention is not affected.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display location C22F 1/043 9157-4K

Claims (2)

[Claims] 1. Si 0.01 to 1.10 wt%, Fe 0.03 to
An aluminum alloy tube containing 0.6 wt%, Cu 0.1 to 1.0 wt%, and Mn 0.1 to 1.6 wt% and containing the balance Al and inevitable impurities by a conform method before being conformed. At 52
A method for manufacturing an aluminum alloy tube for a heat exchanger, which comprises performing a heat treatment at 0 ° C or higher. 2. Si 0.01 to 1.10 wt%, Fe 0.03 to 0.
6 wt%, Cu 0.1-1.0 wt%, Mn 0.1-1.6 wt%, Mg 0.5 wt% or less, Cr 0.3 wt% or less, Zr
Before manufacturing the aluminum alloy tube containing one or two or more of 0.3 wt% or less and Ti 0.3 wt% or less and the balance Al and unavoidable impurities by the conform method, aluminum before conforming A method for producing an aluminum alloy tube for a heat exchanger, which comprises subjecting an alloy to heat treatment at 520 ° C or higher.