JPH08277433A - Brazing sheet and tube used for heat exchanger - Google Patents

Abstract

PURPOSE: To obtain a brazing sheet excellent in pitting corrosion resistance and erosing resistance by manufacturing the brazing sheet by an Al alloy material contg. a specified amt. of Mn and an Al alloy brazing filler metal contg. Si and Zn by the amounts shown by the inequalities. CONSTITUTION: A brazing sheet is manufactured by an Al alloy material contg., by weight, 0.1 to 2.0% Mn and an Al alloy brazing filler metal contg. Si and Zn by the amounts satisfying the inequality: -0.20 [Zn]+7.0<=[Si]<=-0.20-[Zn]+12.6 and the inequality: 4.0<=[Zn]<=25.0 ([Zn] denotes the content (wt.%) of Zn and [Si] denotes the content (wt.%) of Si). Thus, the brazing sheet useful for constituting a tube in an automobile heat exchanger can be obtd.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a brazing sheet used for forming tubes in heat exchangers such as radiators, heater cores, evaporators and oil coolers for automobiles.

[0002]

BACKGROUND OF THE INVENTION A heat exchanger made of aluminum or aluminum alloy material (hereinafter referred to as Al material) has a brazing material bonded to an extruded flat multi-hole tube (tube) or header pipe made of the Al material. It is manufactured by assembling a clad fin manufactured using a brazing sheet, supplying flux to a joint between a tube or a header pipe and a clad fin, and brazing in an inert atmosphere.

Alternatively, a brazing sheet in which a brazing material is clad is used to form a tube or the like, fins are assembled to the tube, flux is supplied to the joint, and brazing is performed in an inert atmosphere. There is. By the way, when a tube or the like is formed by using a brazing sheet in which a brazing material is clad, Mn is 1 to 1.5 wt% and C as a core material of the brazing sheet.
Al-Mn-Cu containing u of 0.05 to 0.2 wt%
An alloy is used, and an Al-Si alloy is used as a brazing material.

However, a heat exchanger having a tube or a pipe made of such a brazing sheet as a constituent element is required to have improved corrosion resistance.

[0005]

DISCLOSURE OF THE INVENTION As a result of intensive studies on the above problems, it has become clear that the problem of corrosion resistance can be solved by considering a brazing material in a brazing sheet. That is, the Al-Si alloy of the brazing material used has a hypoeutectic composition from the viewpoint of brazing property and erosion resistance, but since it contains Si, the corrosion resistance, especially the pitting corrosion resistance decreases. To do. In order to improve this, it has been attempted to reduce the potential of the brazing material by adding Zn in the range of several% to ten and several%. By the way, in the case of Al-Si binary alloy, the eutectic composition is Si-12.6 wt%,
In the case of Al-Si-Zn ternary alloy further containing Zn, the eutectic composition deviates from Si-12.6 wt%. For example, the eutectic composition when Zn is contained at 10 wt% is Si-about 10 wt%. Therefore, depending on the amount of Si contained in the brazing filler metal, Zn added to improve the corrosion resistance results in a hypereutectic composition. When a brazing filler metal having such a hypereutectic composition is used, the presence of primary crystal Si is likely to erode and facilitate the formation of through holes. Also, the erosion resistance is poor. Further, when such a brazing material is clad to be rolled, rolling cracks or the like occur.

Therefore, Al-Si-Zn as a brazing material
It was thought that the above problems would be solved by specially defining the Si content and Zn content in the alloy, and as a result of intensive experiments, the following formulas [1] and [2] were obtained. The Si content and the Zn content are defined so as to satisfy, and the formula [1] −0.20 [Zn] + 7.0 ≦ [Si] ≦ −0.20 [Zn] +12.6 [2] Formula 4. 0 ≦ [Zn] ≦ 25.0 [where [Zn] is the Zn content (wt%) contained in the Al alloy brazing material, and [Si] is S contained in the Al alloy brazing material)
i content (wt%)] We have come to find an Al alloy in which the balance is Al and inevitable impurities.

The present invention has been achieved based on such knowledge, and an object thereof is to provide a brazing sheet having both excellent pitting corrosion resistance and erosion resistance.
An object of the present invention is to provide an Al alloy material containing 0.1 to 2.0 wt% of Mn, and an Al alloy brazing material containing amounts of Si and Zn satisfying the above expressions [1] and [2]. It is achieved by a brazing sheet characterized by comprising.

An Al alloy material containing 0.1 to 2.0 wt% Mn and 0.1 to 0.6 wt% Si,
It is achieved by a brazing sheet characterized by comprising an Al alloy brazing material containing Si and Zn in an amount satisfying the above formulas [1] and [2]. Also, 0.1
2.0 wt% Mn, and 0.1-0.5 wt% Cu
And a Al alloy brazing material containing an amount of Si and Zn that satisfies the above formulas [1] and [2].

Further, 0.1 to 2.0 wt% of Mn, 0.1
~ 0.5 wt% Cu, and 0.1-0.6 wt% S
It is achieved by a brazing sheet comprising an Al alloy material containing i and an Al alloy brazing material containing amounts of Si and Zn satisfying the above formulas [1] and [2]. In addition, Al in the brazing sheet
The alloy material (core material) is 0.01 to 0.20 wt% Zr,
0.01 to 0.20 wt% Ti, 0.05 to 0.30
It is preferable to contain one or two or more kinds selected from wt% Cr and 0.01 to 0.15 wt% V. That is, the Al alloy material in the brazing sheet of the present invention contains 0.1 to 2.0 wt% of Mn, and the balance is A
alloy consisting of 1 and unavoidable impurities, 0.1 to 2.0 wt
% Mn, and 0.1-0.6 wt% Si,
An alloy in which the balance is Al and inevitable impurities, 0.1 to
2.0 wt% Mn, and 0.1-0.5 wt% Cu
An alloy containing Al and the balance consisting of Al and unavoidable impurities,
Or 0.1-2.0 wt% Mn, 0.1-0.5 wt
% Cu, and 0.1-0.6 wt% Si,
In addition to the alloy whose balance is Al and unavoidable impurities, the alloy further contains 0.01 to 0.20 wt% Zr, 0.01
.About.0.20 wt.% Ti, 0.05 to 0.30 wt.% Cr, and 0.01 to 0.15 wt. This is 0.01-0.20 wt% Zr, 0.01-0.
20 wt% Ti, 0.05-0.30 wt% Cr,
When 0.01 to 0.15 wt% V or the like is contained,
This is because the strength is improved. Further, Zr, Ti, Cr and the like prevent the crystal grains thinly stretched in the rolling direction from being coarsened by the heat treatment. The prevention of this coarsening prevents pitting corrosion inside the core material. Therefore, also from this point, it is extremely preferable to contain the element. Incidentally, a more preferable range of the Zr content is 0.07 to
0.15 wt%, the more preferable range of Ti content is 0.1.
07-0.15 wt%, more preferable range of Cr content is 0.07-0.15 wt%, and more preferable range of V content is 0.05-0.12 wt%.

Mn in the Al alloy material in the brazing sheet is an essential element from the viewpoint of ensuring the mechanical strength of the brazing sheet. That is, if Mn is not contained, the required mechanical strength cannot be secured. From this point of view, the content is set to 0.1 wt% or more. However, even if the Mn content increases, the improvement in mechanical strength cannot be proportionally obtained, and the workability and thermal conductivity decrease. In the case of a component of the heat exchanger, for example, a tube or a tube such as a header pipe, in order for the heat exchange medium to flow through the inside and heat exchange to be performed efficiently, the pipe material is made of a heat conductive material. Good sexuality is essential. Therefore, the Mn content is set to 2.0 wt% or less. The preferable range of Mn content is 0.5 to 1.5 wt%
Is.

It is preferable to contain Si in addition to the above Mn. That is, Si is solid-dissolved in the matrix to improve the mechanical strength. However, since Si becomes a noble deposit electrochemically, there is a concern that the corrosion resistance may be deteriorated, so the content was made 0.6 wt% or less. If the amount is small, the effect is not obtained, so the content is set to 0.1 wt% or more. A more preferable range of Si content is 0.2 to 0.5 wt%.

Further, the inclusion of Cu can be expected to improve the mechanical strength. Further, by containing Cu, ductility is improved and workability is improved. Therefore,
It is extremely preferable to also contain Cu. The amount of Cu contained in order to exert such characteristics is 0.1 to 0.5 wt%. If it exceeds 0.5 wt% and becomes too large, intergranular corrosion begins to occur. And
0.1-0.5 wt% (more preferable content is 0.1-0.5%)
If it is about 0.3 wt%), the mechanical strength and the workability are improved, the corrosion resistance is also improved, and the problem of thermal conductivity does not occur.

The brazing material clad on the surface (one side or both sides) of the core material made of the Al--Mn alloy as described above is
An Al alloy containing Si and Zn in an amount satisfying the above formulas [1] and [2], and the balance being Al and inevitable impurities. A brazing sheet obtained by clad an Al alloy brazing filler metal having such a composition with a core material made of the above Al-Mn alloy has excellent pitting corrosion resistance and erosion resistance.

Here, the Si content is defined by the formula [1] so that the composition of the brazing material is a hypoeutectic composition to eliminate the concern about erosion resistance. That is, [Si] <-
If it is 0.20 [Zn] +7.0, the liquid phase of the brazing material during brazing will be insufficient, the fluidity will decrease, and the brazing characteristics will deteriorate. On the contrary, [Si]>-0.20 [Zn] +1
When it becomes 2.6, the composition becomes hypereutectic and, for example, the corrosion of the brazing material on the fin becomes remarkable.

A more preferable range is the range represented by the following formula [3]. [3] Formula −0.20 [Zn] + 7.5 ≦ [Si] ≦ −0.20 [Zn] +10.5 The reason why Zn is contained in the brazing filler metal is that the corroding form of the brazing filler metal is a general corrosion type. This is because it is difficult to cause local corrosion.
Further, when Zn is contained, the potential is lowered and the sacrificial anode effect on the core material is improved. In order to effectively exhibit these, the Zn content is defined by the formula [2]. A more preferable range is 6.0 ≦ [Zn] ≦ 16.0, and a particularly preferable range is 7.0 ≦ [Zn] ≦ 12.0.

The relationship between [Si] and [Zn] is shown in FIG. The thickness of the core material made of the Al-Mn-based alloy and the brazing material made of the Al-Si-Zn-based alloy to be clad is 0.95 / 0.05 to 0.75 /
It is about 0.25. Then, the object of the present invention is achieved by a tube used in a heat exchanger, characterized in that the brazing sheet having the above-mentioned structure is formed into a tubular shape so that at least the Al alloy brazing material is exposed on the surface.

The present invention will be described in detail below.

[0018]

Example A brazing sheet was prepared in which a brazing material made of an Al alloy shown in Table 1 was clad on both surfaces of a core material made of an Al alloy shown in Table 1 below. In addition, this brazing sheet has a brazing material / core material / brazing material = 0.1 / 0.8
The thickness is 0.40 mm with a ratio of /0.1.

Then, a tube was prepared using this brazing sheet, and this tube and the Al alloy fin were brazed by using a fluoride-based flux in a nitrogen atmosphere at 600 ° C. for 5 minutes. Table-1 Core material component (wt%) Brazing material Mn Si Cu Ti Cr Zr V Al Example 1 0.5 − − 0.11 − − − Remaining Al-9Si-6Zn Example 2 1.0 − − − 0.15 − − Remaining Al- 8Si-10Zn Example 3 1.5 − − − − 0.10 − Remaining Al-6Si-6Zn Example 4 0.5 0.2 − − 0.15 − 0.10 Remaining Al-8Si-12Zn Example 5 1.0 0.3 − − − − Remaining Al-5Si- 15Zn Example 6 1.5 0.5 − 0.10 − − − Remaining Al-7Si-20Zn Example 7 0.5 − 0.15 − − − − Remaining Al-3Si-20Zn Example 8 1.0 − 0.30 − − 0.12 − Remaining Al-4Si-22Zn Comparison Example 1 0.5 − − 0.10 − − − Remaining Al-4Si-8Zn Comparative example 2 1.0 − − − 0.11 − − Remaining Al-10Si-20Zn Comparative example 3 1.5 − − − − 0.10 − Remaining Al-9Si-2Zn Comparative example 4 1.0 0.3 − 0.10 − − 0.10 Remaining Al-5Si-28Zn Comparative Example 5 1.0 − 0.15 − − − − Remaining Al-13Si-2Zn Comparative Example 6 1.0 − 0.30 − − 0.12 − Remaining Al-1Si-27Zn Regarding the obtained one , Tube resistance It was studied the junction rate between sex and fins, and the results are shown in Table 2.

Table 2 Acid Salt Spray Test Corrosion Solution Circulation Test Brazing Penetration Rate Pitting depth after 30 days Pitting depth after 30 days Piping depth Example 1 0.03 mm 0.04 mm 20 μm 95% Example 2 0.04 mm 0.05 mm 25 μm 98% Example 3 0.03 mm 0.05 mm 30 μm 98% Example 4 0.05 mm 0.07 mm 32 μm 99% Example 5 0.05 mm 0.08 mm 35 μm 95% Example 6 0.04 mm 0.09 mm 28 μm 97% Example 7 0.05 mm 0.08mm 33μm 98% Example 8 0.06mm 0.08mm 36μm 96% Comparative Example 1 0.05mm 0.05mm 20μm 48% Comparative Example 2 0.06mm 0.07mm 80μm (through) 100% Comparative Example 3 0.35mm 0.40mm (through) 30μm 95 % Comparative Example 4 0.25 mm (entire depth) 0.30 mm (entire depth) 35 μm 95% Comparative Example 5 0.06 mm 0.07 mm 80 μm (penetration) 100% Comparative Example 6 0.08 mm 0.09 mm 38 μm 37%

[0021]

[Effect] A heat exchanger with excellent corrosion resistance and mechanical strength can be obtained.

[Brief description of drawings]

FIG. 1 is a graph showing the relationship between [Si] and [Zn].

Claims (6)

[Claims] 1. An Al alloy material containing 0.1 to 2.0 wt% of Mn, and an Al alloy brazing material containing Si and Zn in amounts satisfying the following expressions [1] and [2]. A brazing sheet characterized by that. [1] Formula −0.20 [Zn] + 7.0 ≦ [Si] ≦ −0.20 [Zn] +12.6 [2] Formula 4.0 ≦ [Zn] ≦ 25.0 [however, [Zn] Is the Zn content (wt%) contained in the Al alloy brazing material, and [Si] is S contained in the Al alloy brazing material.
i content (wt%)] 2. Mn of 0.1 to 2.0 wt% and 0.
A brazing sheet comprising an Al alloy material containing 1 to 0.6 wt% of Si and an Al alloy brazing material containing amounts of Si and Zn satisfying the following formulas [1] and [2]. . [1] Formula −0.20 [Zn] + 7.0 ≦ [Si] ≦ −0.20 [Zn] +12.6 [2] Formula 4.0 ≦ [Zn] ≦ 25.0 [however, [Zn] Is the Zn content (wt%) contained in the Al alloy brazing material, and [Si] is S contained in the Al alloy brazing material.
i content (wt%)] 3. Mn of 0.1 to 2.0 wt% and 0.
A brazing sheet comprising an Al alloy material containing 1 to 0.5 wt% of Cu and an Al alloy brazing material containing Si and Zn in an amount satisfying the following formulas [1] and [2]. . [1] Formula −0.20 [Zn] + 7.0 ≦ [Si] ≦ −0.20 [Zn] +12.6 [2] Formula 4.0 ≦ [Zn] ≦ 25.0 [however, [Zn] Is the Zn content (wt%) contained in the Al alloy brazing material, and [Si] is S contained in the Al alloy brazing material.
i content (wt%)] 4. 0.1-2.0 wt% Mn, 0.1-0.1%
0.5 wt% Cu and 0.1-0.6 wt% Si
A brazing sheet comprising an Al alloy material containing Al and an Al alloy brazing material containing Si and Zn in an amount satisfying the following formulas [1] and [2]. [1] Formula −0.20 [Zn] + 7.0 ≦ [Si] ≦ −0.20 [Zn] +12.6 [2] Formula 4.0 ≦ [Zn] ≦ 25.0 [however, [Zn] Is the Zn content (wt%) contained in the Al alloy brazing material, and [Si] is S contained in the Al alloy brazing material.
i content (wt%)] 5. The Al alloy material is 0.01 to 0.20 wt.
% Zr, 0.01 to 0.20 wt% Ti, 0.05
The brazing sheet according to any one of claims 1 to 4, wherein the brazing sheet contains one or more selected from the group of 0.30 wt% Cr and 0.01 to 0.15 wt% V. 6. A tube used in a heat exchanger, characterized by being formed by tubular processing of the brazing sheet according to any one of claims 1 to 5 so that at least an Al alloy brazing material is exposed on the surface. .