JPS5923837A - Al alloy clad material - Google Patents

Abstract

PURPOSE:To provide a titled clad material which has excellent brazability and resistance to pitting corrosion and of which the coating material itself can be a brazing material by coating a core material of an Al material with an alloy consisting of the compsn. around a Zn-Al eutectic compsn. CONSTITUTION:An Al alloy clad material consisting of pure Al or optional Al alloy as a core material and an alloy composed of a compsn. around a Zn-Al eutectic compsn. as a covering material provides excellent resistance to pitting corrosion as the coating material itself forms several tens mu Zn diffused layers in the other material. A Zn-Al alloy contg. about several%-25% Al is usable as the above-mentioned coating material, and said material has excellent ductility, is free from cracking defects in the rolling stage in the manufacture of the clad material and is rollable satisfactorily with the core material. The material has a relatively low m.p. and provides the effect of a brazing material at a low temp.

Description

[Detailed description of the invention] The present invention provides A and I having excellent brazing properties and pitting corrosion resistance.
Regarding J alloy clad material.

As A1 alloy clad materials for vacuum brazing or atmosphere brazing materials, those shown in FIGS. 1(A) and 1(B) have been known.

Fig. 1 (A) A so-called brazing material in which the core material 1 is an A1 alloy such as 1000 series or 5000 series, and the core material 2 is an Al-Si alloy (4000 series alloy) with various additive elements added. Figure 1 (B) is ioo.

The core material 1 is an AI alloy alloy such as 6000 series or 6000 series, and Al-Zn series, A7-Mn-Zn, which has a lower corrosion potential than the core material 1.
This is a so-called sacrificial anticorrosive cladding for the purpose of cathodic protection of the core material 1 using alloys such as A7-8n, A7-8n, and Al-In as the covering material 5.

However, in the case shown in FIG. 1(A), the coating layer 2 is made of an α+β two-phase alloy, which has poor corrosion resistance (and has the disadvantage of causing through-pitting corrosion in a short period of time when used for heat exchanger tube materials, etc.). In the case shown in Fig. 1(B), the difference in corrosion potential between the core material 1 and the coating layer 6 after brazing is not so large, and the cathodic protection effect cannot be expected to be as good as that of the base material. It is essential to use a clad material for brazing, and if the mating material is thin, such as the fin material of an air conditioning heat exchanger, the brazing area is small and the strength and heat conduction are low. there were.

The present invention provides an A1 alloy clad material that has high corrosion resistance after brazing and can also be used as a brazing material.

1- That is, the present invention relates to an A1 alloy clad material having a core material made of pure Ad or any Al1 alloy and an alloy coating material having a composition near the zn-Al eutectoid composition.

FIG. 2 is a diagram showing the structure of the cladding material of the present invention.

In Figure 2, 1 is pure Al or 1000 series, 3000
core material of any other A1 alloy, 4 is Z n -A
This is an alloy coating material having a composition near the eutectoid composition of No. 13.

As a 4σ no example of this coating material, 78%Zn-22%
Al is also known as a superplastic alloy, and is highly ductile, so it may be possible to roll it well with the core material 1, such as cracks or defects in the rolling process during the manufacturing of the cladding 4J.

In addition, the alloy of this covering material 4 has a liquidus line of approximately 480''C1 and a common phase line of approximately 425''C, which is lower than the conventional Goo 3 Al-Si based brazing material, and has a low melting point as a brazing material at low temperatures. ) and also acts effectively as a sacrificial anticorrosive to improve pitting corrosion resistance.

In addition to the above-mentioned 78 modulus Zn-22 modulus Al, a Zn-A7 alloy containing approximately several to 25% Al can be used as the cladding material σ-4 alloy of the present invention.

When the cladding material of the present invention described in L is brazed to another A1 alloy, for example, the mating A1 alloy does not need to be a cladding material for brazing filler metal.

FIG. 6 is a diagram showing the Zn concentration distribution in the σ cross section after brazing the cladding phase of the present invention and the mating material, in which A represents the coating layer of the cladding material of the present invention, and B represents the coating layer in the 1-0 shows a Zn diffusion layer formed by diffusion of Zn into the mating material.1-0 Thus, according to the cladding phase of the present invention, several tens of micrometers of Zn is diffused into the mating material.
It is a J-stone σJ that forms a diffusion layer and exhibits excellent pitting corrosion resistance due to the Zn diffusion layer.

Example: An aluminum heat exchanger was manufactured using the clad material of the present invention as a tube phase.Material: Tube; 5005 series A1 alloy core 4J' [78% Z
N-22 Al alloy 7 cladding with 5 clad ratio σ), tube wall thickness 0.5 mm Fin; 3005 series AI alloy bare removal process: Tube and fin jig assembly I2) Degreasing and etching (with alkali or acid) → wax printing (warm [50
0''C1 hour 5 minutes, W enclosure N2 ('a,t ding r+
)) > Result: Fint tube joint fin R-shaped H.

The condition is good, and the manufactured heat exchanger is JIS
Z2.571-76 salt water spray test 2000 hours, JIS DO201-76 acid salt spray test (C
ASS test) When the pitting corrosion occurrence state was investigated after 1000 hours, the pitting depth was less than the Zn diffusion layer under the cladding layer (f, that is, there was no pitting corrosion depth of several tens of microns or less), which was excellent. Blood 1 pitting was confirmed.

The cladding phase of the present invention described above can be effectively applied to all AI-tJ1 alloy structures assembled by brazing, especially K Al heat exchangers.

[Brief explanation of drawings]

11 Pi (A) and (13) show the cladding material of conventional vacuum brazing or atmosphere brazing DJ; FIG. 2 shows the cladding material of the present invention; Cross section after brazing with the mating phase 7. ++ is a chart showing concentration distribution.

Claims (1)

[Claims] An A1 alloy clad material having pure A, L or any A7 alloy as a core material and an alloy having a composition close to the Zn-Al eutectoid composition as a coating material.