JPS6296637A - Aluminum alloy-clad material for heat exchanger - Google Patents

Abstract

PURPOSE:To obtain an Al alloy-clad material for heat exchanger improved in strength and corrosion resistance by using as core material an alloy prepared by incorporating specific percentage of Cu, Mn, and Mg to Al and by cladding the surface of the above alloy with Al-Si brazing filler metal. CONSTITUTION:The alloy consisting of, by weight, 0.1-1.0% Cu, 0.3-1.5% Mn, 0.1-1.0% Mg, and the balance Al with inevitable impurities and containing, if necessary, 1 or >=2 kinds among <=0.3% Cr, <=0.25% Zr, and <=0.3% Ti is prepared. This alloy is used as core material, which is clad with the Al-Si brazing filler metal on one side or both sides thereof by the ordinary method. In this way, an Al alloy-clad sheet for heat exchanger improved in strength and corrosion resistance in a heat exchanger made of Al which is to be assembled by 'Al can Nocolok(R)' brazing can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a plating sheet for a heat exchanger manufactured by brazing using a fluoride flux.

Conventional technology In general, the flux brazing method, the vacuum brazing method, and the Nocolock (Alcan, Brax trademark, the same applies below) brazing method are used to manufacture Ryolumi heat exchangers, but recently Nocolock has been used. Laws have come to be used frequently for brazing. Nokolock brazing method is JIS1050 (purity 99
．． 5wt% or more pure Al) C or less wt%f], 3003 (Al-0.05~0.20%Cu-1
,0~1.5%Mn alloy), 3203(Al-1,0~
JIS4343 (1.5% Mn alloy) etc. as the core material,
-6,8~8.2-inch Si alloy], 4045 (Al-9
, 0 to 11.0% Si alloy] is used as a brazing material, and brazing is performed in N2 gas using a fluoride-based non-corrosive flux. Low cost and easy maintenance
It has advantages such as not requiring post-treatment of flux. That is, the flux residue produced by Nocolock brazing is not hygroscopic, soluble, or corrosive, and brazing using chloride-based flux does not require subsequent cleaning of the residue. .

Problems that the invention aims to solve: The conventional method using a flux containing Z n CL x has the effect of forming a diffused layer and preventing the occurrence of pitting corrosion. The serpentine type condenser, evaporator, etc. tube shown in the figure (1
), it is necessary to precipitate Zni by zincate treatment, etc., and during brazing, it is necessary to completely diffuse Zn by heating, and in the radiator shown in FIG. 3, it is necessary to improve the corrosion resistance by combining with the sacrificial fin (21) containing Znk.

In addition, Nocolok brazing is applied to the tube material in order to improve the strength of the radiator shown in Figure 3.
S 3005 (Al-1, 0~1.5%Mn-0,
2~0.6% Mg alloy], 3105 (Al-0,3~
0.8%Mn-0.2~0.8%Mg alloy] etc. 7, header plate (3) [JIS3005.31o
5.6951 (Al-0,2~0.5%S i-0,1
A Mg-containing flux residue is formed on the surface of 5-0.4% Cu-0,4-(1).

As a result, the potential on the surface of the tube becomes base, and the potential difference with the sacrificial fin becomes less than 50 mV, or the potential between the tube and the fin is reversed.1-1 The effect of sacrificial fins may not be fully exhibited, especially when containing Mg. It becomes noticeable when the amount is 0.3% or more.

The Mg-containing flux residue in Makunokorok brazing has insulating properties and inhibits the anticorrosive current flowing to the fins [1] Suppresses the fin sacrificial effect. In particular, when brazing is performed with a high flux concentration to improve properties, not only will the potential become cyclized, but the residue will also become thicker, making it even more difficult for the anti-corrosion current to flow.

As a means to solve this problem, we have developed an aluminum alloy clad plate for heat exchangers that can improve both strength and corrosion resistance.

That is, one of the clad plates of the present invention has Cu0.1 to 1.0
Contains Mn0.3-1.5%, Mg0.1-1.0%,
The core material is an alloy consisting of the remainder Al and unavoidable impurities, and one or both sides of the core material are coated with an Al-3t brazing sound cladding.

Another clad material of the present invention is Cu 0.1-1
．． 0%, Mn0.3-1.5%, Mg0.1-1.0%
Contains Cr 0.3% or less, Z r 0.25
The core material is an alloy containing one or more of Ti within the range of 0.3% or less, the balance being Al and unavoidable impurities, and an Al-5i brazing filler metal on one or both sides of the core material. It is characterized by being clad with.

Function: The reason why the alloy composition of the core material in the clad material of the present invention is limited as described above is as follows.

Although the addition of Cu improves the strength of the core material and improves the potential, the effect is insufficient if the content is less than 0.1 inch.
This is because if it exceeds 1.0 inch, the corrosion resistance of the core material decreases and the workability deteriorates. Mn additive 77o gives high temperature strength to the core material, and if its content is less than 0.3%, sufficient strength cannot be obtained at high temperatures, and if it exceeds 1.5%, it will cause coarse AL-Mn compounds. This is because it forms and deteriorates workability. 7'i: Added to Mg to improve the strength of the core material. If the content is less than 0.1%, sufficient strength cannot be obtained, and if it exceeds 1%, brazing of Nocolock brazing may occur. Sometimes, it accelerates the diffusion of the brazing filler metal into the core material, reducing the brazing properties and reacting with the fluorine in the flux (KAzF). This is because it decreases.

Furthermore, the addition of one or more of Cr-ZrsTt was added in order to further increase the high temperature strength without impeding brazing properties, and none of them exceeded the upper limit. When added, a huge compound Al-Cr%Al-Zr%A
l-T i QIt-precipitation, which significantly reduces the workability of the core material. Also, rather than adding any of these alone, 2
It is more effective to add more than one seed.

The above core material is coated with Al on one or both sides by conventional means.
By cladding with -3i brazing filler metal, especially used for radiator tube material, Nocolock brazing improves the subsequent strength and corrosion resistance of the radiator core in combination with sacrificial fins.

That is, Cu is added to increase the strength, and Mn and Mg
In the case of cladding with Al-Si brazing material on one or both sides of the tube material, the tube material surface potential can be suppressed from cyclization L2, and the potential difference with the sacrificial fin can be fully ensured by Nocoroc brazing. Improves corrosion resistance.

Examples An alloy having the composition shown in Table 1 was used as a core material, and one side of the core material was an alloy with a cladding ratio of 1 (l) equivalent to JIS 4045 [ht-1os
Si alloy] clad, plate thickness 0.4 mm, temper H1
4 praising sheets were created.

A sample with a width of 3° and a length of 200 cm was cut out from this plating sheet, and a N1
After heat treatment at 600℃ in gas for 10 minutes, JISS
The strength was measured by processing it into a No. 1 test piece, and the width was 50tms.
A sample with a length of 100 mm was cut out, degreased with acetone, coated with a Franks aqueous solution of potassium aluminum fluoride at a concentration of 50 mm, dried at 150 °C, and heated to 600 °C in N8 gas for 10 min to simulate Nocolock brazing as described above. In addition to measuring the potential of the heat treated for minutes, JIS30
A Nalphine material (thickness: 0.1 m, width: 50 m, length: 100 m) made of 03+1% Zn was similarly heat-treated and then its potential was measured. The potential was measured using saturated Carmelo electrodes (S, C, E) as a reference after 10 minutes of immersion in 5% Nacz at 20°C.

Next, a flat tube (1) with a thickness of 22 cm and a width of 16 cm as shown in Fig.
Made of 3003 + 1% Zr, thickness 0, 1 + m, width] 6
The fin material of (2) is combined with the corrugated fin (2) to form a core, and after degreasing with acetone, a 5% aluminum potassium fluoride salt flux aqueous solution is applied, and the temperature is heated to 150°C.
After drying it, it was heated to 600° C. for 10 minutes in N2 gas and brazed to create a radiator core. Regarding this, a salt spray test according to JIS Z2371 was conducted, and the time required until penetration pitting corrosion occurred in the tube was investigated.

These results are also listed in Table 1.

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As is clear from Table 1, the alloy of the present invention No. 1
The strength of all of the clad materials of the present invention having a core material of ~12 is 1.
4 Kv/- or more, the potential difference with the fin material is 50 mv or more, and the corrosion resistance of the radiator core using this is extremely good, and no pitting corrosion was observed even in a 4000-hour salt spray test. It can be seen that a good radiator core cannot be produced using a plating sheet using all comparative alloys No. 13α20 whose alloy composition deviates from that of the material. That is, comparative alloy Na1 with low Cu content
3 and comparative alloy No. 15 with a low Mn content as core materials, the corrosion resistance was poor and the C
Comparative alloy Na14 with a high u content, Comparative alloy 16 with a high Mn content, and comparative alloy NIIL19.2 with a high total content of one or more of (:r, 7.r, Ti)
No. 0 had poor processability, and we gave up on using it as a plating sheet. Comparative alloy N11 with high Mg content
The brazing sheet using 18'e had poor brazing properties, so we gave up on making a radiator core.

As described above, according to the present invention, Nocolok brazing prevents the cyclization phenomenon of the surface potential due to the reaction between the Mg contained in the core material and the fluorine in the flux in the production of aluminum heat exchangers by the method. It improves corrosion resistance without reducing the strength improvement effect of addition, and has remarkable effects such as making it possible to reduce the thickness of a heat exchanger material.

[Brief explanation of drawings]

FIG. 1 is a perspective view showing an example of a radiator core prepared for evaluating the clad material of the present invention, FIG. 2 is a perspective view showing an example of a servator type capacitor core,
FIG. 3 is a perspective view showing an example of a radiator core. 1 Tube 2 Fin 3 Ladder plate

Claims (1)

[Claims] (1) Cu0.1-1.0Wt%, Mn0.3-1.5
For a heat exchanger, the core material is an alloy containing 0.1 to 1.0 Wt% of Mg and the remainder Al and unavoidable impurities, and one or both sides of the alloy are clad with an Al-Si brazing filler metal. Aluminum alloy clad material. (2)C
u0.1-1.0wt%, Mn0.3-1.5wt%,
Contains Mg0.11.0wt% and further contains Cr0.3wt%
Hereinafter, an alloy containing one or more of Zr of 0.25 wt% or less and Ti of 0.3 wt% or less, and the balance consisting of Al and unavoidable impurities is used as a core material, and Al-Si is coated on one or both sides of the core material. An aluminum alloy clad material for heat exchangers characterized by being clad with a brazing filler metal.