JPH07144220A - Composite material of aluminum alloy for electric resistance welded tube - Google Patents

Abstract

PURPOSE:To obtain a sufficient joining strength which is suitable for manufacturing tube for radiators or the like by electric resistance welding. CONSTITUTION:Reference is made to a composite material 7 of aluminum alloy for electric resistance welded tube which is clad with a brazing filler metal of Al-Si based alloy on one side of a core material and a sacrificing anode material on the other side. After the electric resistance welded tube is formed, an angle alpha of 95 to 120 deg. is formed by the surface to be the outer side of the tube and the surface to be joined.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an aluminum alloy composite material for an electric resistance welded pipe, which is suitable for manufacturing a tube for a radiator or the like by electric resistance welding.

[0002]

2. Description of the Related Art For example, a radiator for an automobile is shown in FIG.
As shown in the front view of FIG. 2A and the sectional view taken along the line AA of FIG. 2B in FIG. 2B, the fins 2 are arranged between the plurality of tubes 1 through which the refrigerant passes, and the header plates 3 are provided at both ends of the tubes 1. , The core 4 is assembled, the tubes 1 and the fins 2 are brazed together, and then the resin tanks 5 and 5 ′ are attached to the header plate 3 through the packing 6. The tube used for the radiator is a brazing sheet made of a brazing material on one side and a sacrificial anode material on the other side with a core sandwiched between them to form an aluminum alloy composite material for electric resistance welded pipes, and this composite material is used as a sacrificial anode material. Is formed inside to form a tubular composite material, and the edge surface of the tubular composite material is continuously electro-welded to be manufactured by electric resistance welding. In the electric welding, as shown in the perspective views of FIGS. 3A and 3B, when a current is passed through the heating coil 8 around the tubular composite material 7, a current flows through the tubular composite material 7 by electromagnetic induction, It is performed by generating heat, melting, and pressing with a pair of rolls 9.

The core material of the aluminum alloy composite material for electric resistance welded pipe maintains the strength of the tube, and the brazing material brazes the fins. The sacrificial anode material diffuses the Zn element contained in the sacrificial anode material into the core material by the heat during brazing to form a Zn diffusion layer that has a base potential and preferentially corrodes to prevent pitting corrosion of the core material. To prevent. The core material of the brazing sheet is JI
S-3003 alloy, JIS-4343 alloy as the brazing material, and JIS-7072 alloy as the sacrificial anode material are used.

[0004]

Originally, electric resistance welding of a tube for a radiator is performed under severe conditions in order to maintain the strength and shape of the tube. As a result, sufficient welding of the tube may occur. There was a problem that strength could not be obtained and a high quality tube could not be obtained stably. Due to the recent demand for thinner tubes and higher strength as automobiles become lighter, the above-mentioned quality problems should be solved together with the addition of a large amount of elements such as Cu that deteriorate the weldability to the core material. It became an issue. Further, since the welded portion is a mixture of the components of these three layers to each layer of the brazing material, the core material, and the sacrificial anode material to some extent, elements such as Cu and Si are added to the core material for thinning and high strength. In that case, the element on the side of the sacrificial anode material of the welded portion will also contain the element, and the sacrificial anode effect will be hindered, resulting in deterioration of the inner surface corrosion resistance of the tube.

[0005]

In the present invention, as a result of intensive studies in view of such a situation, sufficient welding strength of the tube cannot be obtained because the current flowing in the tubular composite material by electromagnetic induction is Because it has a characteristic that it can easily flow outside,
The outer side of the tubular composite, that is, the side coated with the brazing material, is sufficiently melted and easily welded, but the inner side of the tubular composite, that is, the side coated with the sacrificial anode material, has sufficient melting. It was difficult to weld because it was not done at the same time, and it was found that joining was not performed over the entire thickness of the plate. This tendency becomes more remarkable as the frequency becomes higher. As a method of solving this problem, the outer edge of the tubular composite material, that is, the inner side of the side coated with the brazing material, that is, the side coated with the sacrificial anode material is formed into an edge shape so that heat is generated first. It was found that it would be improved by putting it. Furthermore, in this case, since the sacrificial anode material is welded before the core material, it is found that the elements contained in the brazing material and the core material are not contained in the sacrificial anode material, or even if contained, the amount is small. Further researches have led to the completion of the present invention.

That is, according to the present invention, Al-Si is formed on one surface of the core material.
In an aluminum alloy composite material for an electric resistance welded pipe in which a brazing material of a system alloy is clad on the other surface, a surface to be joined to a surface which is an outer side of the electric resistance welded pipe after forming the electric resistance welded pipe is 95 to 12
The aluminum alloy composite material for electric resistance welded pipes is characterized by forming an angle of 0 °. FIG. 1 shows a cross-sectional view of the tubular composite material immediately before welding, where α is the angle formed between the outer surface of the electric resistance welded tube and the surface to be joined.

Here, the respective components of the brazing material, core material and sacrificial anode material of the aluminum alloy composite material used in the present invention,
The cladding rate is not limited at all. J for brazing material
IS-4343, JIS-4045, etc. may be used.
JIS-3003 may be used for the core material, or high strength Al-1.1Mn-0.8wt% Si-0.1Mg or Al
The present invention exerts a great effect when -1.1 Mn-0.6 wt% Si-0.8 wt% Cu or the like is used. JIS-7072 or Al-2.0 wt% Zn-1.0 is used for the sacrificial anode material.
You may use wt% Mg, Al-0.02In, etc.

In the present invention, the angle between the outer surface of the aluminum alloy composite material for electric resistance welded pipe and the surface to be joined with the surface to be joined is set to 95 to 120 ° by using a bite or the like immediately before forming into a tubular shape. It may be cut continuously.

[0009]

In the present invention, the angle formed between the outer surface of the aluminum alloy composite material for electric resistance welded pipe and the surface to be joined with the surface to be joined is set to 95 to 120 ° because the angle below 95 ° means that the inside of the tubular composite material is This is because sufficient welding cannot be performed, or even if sufficient welding is performed, the sacrificial anode material contains a large amount of elements contained in the brazing material and the core material. If it exceeds 120 °, on the contrary, the outside of the tubular composite cannot be sufficiently welded. 95
By setting the angle to 120 °, the inside of the tubular composite material before welding will generate heat earlier than the outside thereof, and the inside of the tubular composite material is prevented from being welded, and sufficient bonding strength can be obtained, and at the same time, the sacrificial anode material can be obtained. It is possible to prevent the inclusion of elements contained in the brazing material and the core material, and to obtain good internal corrosion resistance.

[0010]

EXAMPLES The present invention will be described in detail below with reference to examples. A brazing material, a core material, and a sacrificial anode material are sequentially stacked to have a thickness of 30.
A 3-mm composite material having a thickness of 0 mm was formed, and this was subjected to hot rolling and cold rolling at 500 ° C. to obtain a composite plate material having a thickness of 0.35 mm. Next, this composite plate material was subjected to intermediate annealing at 330 ° C. for 2 hours and then cold rolled to obtain H14 having a thickness of 0.25 mm.
The brazing sheet of was produced. As the brazing material of the three-layer composite material, a plate material having a thickness of 30 mm obtained by hot-rolling a water-cooled cast material of JIS-4045 alloy after face-shaping was used. As the sacrificial anode material, a plate material having a thickness of 30 mm obtained by hot-rolling a water-cooled cast material of Al-2 wt% Zn was used. The core material is Al-
0.6 wt% Si-1.0 wt% Cu-1.1 wt% Mn-
Thickness 240m obtained by chamfering water-cooled casting of 0.15Mg alloy
m plate material was used. The H14 brazing sheet was hung on a rotary blade type slitter to form a composite material having a width of 50 mm. Next, the angle between this band-shaped composite material and the surface to be joined to the outer surface of the electric resistance welded pipe with the bite is 60 to 1 as shown in Table 1.
It was cut to 50 °, formed into a tubular shape with the sacrificial anode material inside, and the edges were continuously electrowelded into a tube. The cross-sectional shape of the tube was a flat tube having a width of 23 mm and a height of 2 mm, and the welding location was located at the center of one R portion. For those that could be welded, a leak test was performed, that is, it was submerged in water and it was confirmed whether air bubbles would come out from the weld. For those without leakage, a pressure resistance test was conducted, that is, one end of the tube was closed, water was sent from the other end to apply pressure, and the pressure at the time of cracking was confirmed. At the same time, it was confirmed whether the crack position was at the welded part. For a flat tube without leakage, a composite material was applied to the brazing filler metal side with a fluoride flux suspended so as to be 5 wt% and dried at 200 ° C in the atmosphere at 600 ° C for 3 minutes in N ₂ gas. Apply brazing heat, seal the brazing material surface with Teflon tape, and add 15ppm to tap water.
After immersing in a corrosive liquid containing Cu ²⁺ at 88 ° C for 8 hours,
A cycle test of leaving it for 16 hours at room temperature was performed for 4 months. The flat tube after this cycle test was carried out by removing the corrosion products, then cutting the flat part in the rolling direction and opening it into a plate shape, and using the optical microscope, the sacrificial anode in the vicinity of the welded part by the depth of focus method. The maximum pitting depth from the wood was measured. The results are shown in Table 1.

[0011]

[Table 1]

As is clear from Table 1, Comparative Example No. 7,
In No. 11, the angle of the edge portion greatly deviated from the range of the present invention, and neither could be welded. Comparative Example No. Nos. 9 and 10 could be welded, but stable welding could not be performed and leakage occurred. Comparative Example No. Although no leakage occurred in Nos. 6 and 8, since the full thickness of the plate could not be welded, cracks occurred at the welded part and the pressure resistance was low.
6 is also inferior in corrosion resistance. Conventional example No. No. 12 also had a slightly low pressure resistance because the entire plate thickness could not be welded. In contrast,
The example of the present invention can perform stable welding, has a high withstand pressure without causing leakage, and is also excellent in corrosion resistance.

[0013]

As described above, according to the aluminum alloy composite material for electric resistance welded pipes of the present invention, it becomes possible to stably weld the entire plate thickness of the welded portion, and the joint strength is high and the corrosion resistance is excellent. A tube is obtained, which has a remarkable industrial effect.

[Brief description of drawings]

FIG. 1 is a sectional view of a tubular composite material immediately before welding.

FIG. 2 is a front view and a sectional view of a radiator for an automobile.

FIG. 3 is a perspective view of a welded portion of an electric resistance welded pipe.

[Explanation of reference symbols] 1 tube 2 fins 3 header plate 4 core 5, 5'resin tank 6 packing 7 tubular composite material 8 heating coil 9 roll

Claims (1)

[Claims] 1. An aluminum alloy composite material for an electric resistance welded pipe in which a brazing material of an Al--Si alloy is clad on one surface of a core material and a sacrificial anode material is clad on the other surface, and the outer surface of the electric resistance welded pipe is formed after the electric resistance welded pipe is formed. The aluminum alloy composite material for electric resistance welded pipes, wherein the surface to be joined and the surface to be joined form an angle of 95 to 120 °.