JPH0673480A - Aluminum brazing sheet - Google Patents

Abstract

PURPOSE:To prevent the deterioration in the brazability of a brazing sheet caused by the diffusion of Mg into a brazing filler metal from a core material by forming the structure of the core material into a double-layered one and respectively specifying the compsns. on the brazing filler metal side and the sacrificial anodic material side. CONSTITUTION:One side of the core material is clad with an Al Si alloy brazing filler metal and the other side is clad with the sacrificial anodic material of the allay of Al-Zn, Al-Zn-Mg or the like to form an aluminum brazing sheet. The structure of the core material of this brazing sheet is formed into a double one. The layer on the brazing filler metal side is constituted of an Al allay consisting of, by weight, 0.5 to 1.5% Mn, 0.5 to 1.0% Cu, 0.5 to 1.0% Si and <=0.2% Mg, and the balance Al with inevitable impurities. The layer of the sacrificial anodic material side is constituted of an Al alloy consisting of 0.3 to 1.0% Si, 0.5 to 1.5% Mg and 0.1 to 1.0% Cu, and the balance Al with inevitable impurities. Furthermore, the thickness on the brazing filler metal side is regulated to one exceeding 50% of the thickness of the whole body of the core material having a double structure. In this way, its strength after being brazed is made high, and its corrosion resistance on the atmospheric side and refrigerant side is made excellent.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an aluminum brazing sheet used for a heat exchanger of an automobile, and more particularly to an aluminum brazing sheet used as a material for a pipe forming a refrigerant passage of a heat exchanger. It is a thing.

[0002]

2. Description of the Related Art Radiators are used in heat exchangers for automobiles.
There are various types such as a car air conditioner, an intercooler, and an oil cooler. For example, a radiator having a structure as shown in FIG. 1 is used. In FIG. 1, (1) is a tube, (2) is a fin, (3) is a header, and (4)
Is a tank. And tube (1), fin (2)
The header (3) is made of an aluminum material, and the tank (4) is often made of resin.

Further, the tube (1), the fins (2) and the header (3) are integrated by brazing using a fluoride-based flux, and the resin tank (4) is mechanically joined (caulked) thereto. And the radiator is manufactured.

This tube material is an Al-Mn alloy 3003 alloy (Al-0.15 wt% Cu-1.1 wt% M
n) as a core material and Al on the fin side (atmosphere side) surface of the core material.
4343 alloy (Al-7.5 wt% S
i), a brazing material such as 4045 alloy (Al-10.0 wt% Si) is clad, and a sacrificial anode material such as an Al-Zn alloy or Al-Zn-Mg alloy is clad on the other surface (refrigerant side). An aluminum brazing sheet having a three-layer structure is made into a flat tube by electric resistance sewing and roll forming. Its plate thickness is 0.3-0.4 mm.

On the other hand, as a fin material, Zn is added to 3003 alloy.
Is used to provide a sacrificial anode effect, and the thickness is 0.08 to 0.11 mm.

As a header material, a brazing material is clad on the atmosphere side of a core material of 3003 alloy, like the tube material,
An aluminum brazing sheet in which a sacrificial anode material is clad on the refrigerant side is used, and its thickness is 1 to 2 mm.

By the way, in recent years, there has been an increasing demand for weight reduction of automobiles, and in order to meet the demand, weight reduction of automobile heat exchangers has also been demanded. Therefore, thinning of each member has been studied, and the aluminum brazing sheet also has an Al-Mn-Cu-based alloy, Al-Si-, as a core material for thinning.
As compared with conventional Al-Mn-based alloys such as Mg-based alloys and Al-Si-Mg-Mn-Cu-based alloys, it has been promoted to adopt alloys having higher strength and higher corrosion resistance.

[0008]

In brazing using a fluoride-based flux, however, the brazing property of the aluminum brazing sheet having the above Mg-containing alloy as the core material is unstable. For example, in brazing sheets used as tube materials, if 0.3 wt% or more of Mg is added to the core material, Mg diffuses from the core material into the brazing material during brazing and F and Mg in the flux applied during brazing react with each other. However, the MgF compound is formed on the surface of the tube material, and the brazing property between the tube material and the fin is significantly deteriorated. Similar brazing defects may also occur at the joint between the header and the tube.

Particularly when the plate thickness of the tubes and fins is thin, Mg not only causes brazing failure as described above, but also diffuses from the inside of the material to the surface of the material during brazing and the inside of the core material. This is a problem because the amount of Mg in (1) significantly decreases and causes a decrease in strength after brazing. Furthermore, a conventional three-layer brazing sheet (that is, a brazing material,
(Since the core material and the sacrificial material each consist of one layer), if 0.3 wt% or more of Mg is added to the core material, the Si in the core material is
And Mg become a compound of Mg ₂ Si and a large amount is precipitated at the grain boundary, and this precipitate causes a problem such as intergranular corrosion.

[0010]

DISCLOSURE OF THE INVENTION The present invention, particularly in an aluminum brazing sheet used as a tube material for a thin radiator, prevents deterioration of brazing property due to diffusion of Mg from the core material into the brazing material, and This is an aluminum brazing sheet that has high strength and high corrosion resistance after brazing.

That is, according to the present invention, an Al-Si alloy brazing material is provided on one surface of the core material, and an Al-Zn alloy alloy or Al is provided on the other surface.
Al clad with a sacrificial anode material such as --Zn--Mg-based alloy
In the brazing sheet, the core material has a two-layer structure, and the layer on the brazing material side of the core material has Mn: 0.5 to 1.5 wt% (hereinafter referred to as wt%).
Is abbreviated as%), Cu: 0.5 to 1.0%, Si: 0.5 to 1.0
%, Mg: 0.2% or less, or each 0.05
Al containing at least 0.3% of Cr, Zn, and Ti, one or more, and the balance Al and unavoidable impurities
An alloy, the layer on the side of the sacrificial anode is Si: 0.3-1.0%, M
g: 0.5 to 1.5%, Cu: 0.1 to 1.0%, or 0.05 to 0.3% of each of Mn, Cu, Zr, and Ti of one or more, and the balance Al and unavoidable impurities. And an alloy of Al and a brazing material-side layer of the core material having a thickness exceeding 50% of the total thickness of the two-layer core material.

[0012]

In the present invention, the core material has a two-layer structure, and a material containing less Mg is used for the layer on the brazing material side of the core material (hereinafter referred to as A material) to reduce the diffusion of Mg into the brazing material. Therefore, the brazing property is prevented from lowering and, at the same time, the function of suppressing the intergranular corrosion due to the intergranular precipitation of Mg ₂ Si is provided. Further, a material containing a large amount of Mg is used for the layer on the side of the sacrificial anode material of the core material (hereinafter referred to as material B) to improve the strength. Further, in both the A and B materials, Cu is added to improve strength and corrosion resistance. Furthermore, since the proportion of the total thickness of the two-layer core material of A material thickness with less Mg exceeds 50%,
By suppressing the amount of intergranular corrosion due to Mg ₂ Si, the balance of strength, brazing property and corrosion resistance is maintained, and each property is improved.

The reasons for adding the additional elements and the reasons for limiting the addition amount in materials A and B will be described below.

In material A, Mn is added to improve strength and corrosion resistance. The amount added is 0.5 to 1.5%. If it is less than 0.5%, there is no effect, and if it exceeds 1.5%, plastic workability deteriorates. Because it does.

Cu is added to improve strength and corrosion resistance. The amount added is 0.5 to 1.0% because it is 0.5%.
If it is less than 1.0%, there is no effect, and if it exceeds 1.0%, the plastic workability deteriorates.

After brazing, Si forms a solid solution in the matrix and is effective in improving strength. The amount added is 0.5 to 1.0% because if it is less than 0.5%, the effect is small, and if it exceeds 1.0%, the amount of elemental Si increases and the plastic workability deteriorates.
This is because there is a risk of causing intergranular corrosion due to grain boundary precipitation of g ₂ Si.

Although Mg has an effect of improving the strength after brazing, if it is added in an amount exceeding 0.2%, it diffuses to the brazing material side to reduce the brazing property, or reacts with Si to react with Mg ₂ S.
There is a risk of causing intergranular corrosion due to precipitation of intergranular grains of i.
Therefore, the amount of Mg should be 0.2% or less.

Cr, Zr, and Ti are all effective in improving the strength, but if each is less than 0.05%, they have no effect, and if over 0.3%, a huge compound is formed and plastic workability is deteriorated. It should be noted that although Fe is preferably added as an impurity in the 3003 alloy, the smaller the amount, the better the corrosion resistance.

In material B, Si is solid-solved in the matrix and is effective in improving strength. The amount added is 0.3 to 1.0% because if it is less than 0.3%, the effect is small, and if it exceeds 1.0%, the amount of elemental Si increases and the plastic workability deteriorates. Furthermore, intergranular corrosion due to precipitation of Mg ₂ Si grain boundaries occurs. Because it may cause

Mg has the effect of improving the strength after brazing,
The addition amount is limited to 0.5 to 1.5% because if it is less than 0.5%, it has no effect, and if it exceeds 1.5%, the ratio of the thickness of material B to the total thickness of the two-layer core material is the specified condition of the present invention. Even if the above condition is satisfied, the amount of intergranular precipitation of the Mg ₂ Si compound due to diffusion after brazing increases, which may cause intergranular corrosion, so that there are many corrosion sites and the corrosion resistance deteriorates. To come.

Cu is effective in improving strength and corrosion resistance. The addition amount is limited to 0.1 to 1.0% because if it is less than 0.1%, the effect is small, and if it exceeds 1.0%, not only the plastic workability deteriorates, but also a large amount of Cu is contained in the sacrificial anode material clad with the core material. This is because the sacrificial anode material lowers the sacrificial anode effect due to diffusion, and the corrosion resistance of the brazing sheet deteriorates.

Mn, Cr, Zr, and Ti are all effective in improving strength, but if each is less than 0.05%, they have no effect.
If it exceeds 0.3%, the plastic workability decreases. Fe is 3
Although the amount of impurities added to the 003 alloy is good, the smaller the amount, the better the corrosion resistance.

Next, in the present invention, a layer (A
The reason for defining the thickness of the material as exceeding 50% of the total thickness of the two-layer core material is described below.

When the proportion of the total thickness of the two-layer core material of A material thickness with a small amount of Mg is 50% or less, that is, the proportion of the thickness of the sacrificial anode material side layer (B material) with a large amount of Mg When the ratio exceeds 50%, theoretically, the strength is improved as much as the amount of Mg is large, but actually, there is a case where the strength is decreased by the amount of Mg. This is B for A material
This is because the layer thickness becomes thinner than that of the material, so that a large amount of Mg is concentrated on the surface of the brazing material due to the brazing, and not only the strength of the core material due to the addition of Mg lowers than expected but also the brazing property deteriorates. . When the ratio of A material thickness is 50% or less, M
Since the thickness of the B material having a large amount of g is thicker than the thickness of the A material, there is a possibility that the intergranular corrosion site may be enlarged due to the precipitation of the Mg ₂ Si compound at the intergranular boundary after brazing. As a result, it will result in accelerating the progress of corrosion.

Therefore, brazing with improved balance of strength, brazing property and corrosion resistance by suppressing a large amount of Mg concentration on the surface of the brazing material due to brazing and suppressing the amount of intergranular corrosion due to Mg ₂ Si. To provide the seat,
The thickness of material A must exceed 50% of the total thickness of the two-layer core material.

In the aluminum brazing sheet of the present invention, the brazing material and the sacrificial anode material each have a clad ratio of 3 to 15.
% Is appropriate. Further, since Cu is added to the material B, Cu may diffuse toward the sacrificial anode material when the brazing heat is applied, which may reduce the potential base-removing effect of Zn and Mg in the sacrificial anode material. As the anode material, it is preferable to use a base alloy having a sufficient potential, containing Zn and Mg at 1 to 2% and 0.5 to 1%, respectively.

[0027]

[Examples] 16 kinds of brazing material side core alloys (that is, a layer on the brazing material side of a two-layer core material) shown in Tables 1 and 2, sacrificial anode material side core alloy (that is, sacrifice of two-layer core material) (The layer on the anode material side)
16 types and 3003 alloys (all alloys contain Fe as an impurity as shown in the table) were cast by die casting and both surfaces were machined to finish. At this time, when the chamfered ingots of the brazing filler metal side core alloy and the sacrificial anode material side core alloy are combined into two layers, the total thickness of the chamfered ingots is always 40 mm. As shown in Tables 3 and 4, various thickness ratios of No. 3 were finished. For the conventional 3003 alloy, the thickness of the chamfered ingot of the alloy is
Finished to 40mm. Also, 4343 alloy was used as the brazing material, and Al-1.5% Zn-0.5% Mg alloy was used as the sacrificial anode material, both were cast in the same manner as the core material, and after face-shaping, hot-rolled to a thickness of 5 mm.

Then, various combinations of the brazing material side core material and the sacrificial anode material side core material are given in Tables 3 and 4, and the brazing material, the brazing material side core material, the sacrificial anode material side core material, and the sacrificial anode material 4 are combined. The sheets were stacked in this order and hot-rolled at 500 ° C. to obtain a clad material having four layers. After that, cold rolling reduces the thickness to 0.35 mm,
An intermediate annealing of 30 ° C. × 2 hr was added and finally cold-rolled to a thickness of 0.25 mm to obtain a sample of H14 material.

With respect to these samples, strength, brazing property,
The corrosion resistance was measured by the following method, and the results are also shown in Table 3 and Table 4.

After heat of brazing with strength of 600 ° C. × 10 min., Cooling at a cooling rate of 100 ° C./min.
After standing for one day, the tensile strength was measured.

As shown in FIG. 2, a corrugated 3003 alloy fin (2) having a brazing property of 0.1 mm and this sample (5) were combined to form a core. Dip in a flux aqueous solution to apply flux, dry at 200 ° C, and then 600 ° C x 3 min in an inert gas.
The brazing heat was applied to measure the bonding rate of the fins.

Corrosion resistance / atmosphere side: The above-mentioned brazing heat core is used, the sacrificial anode material side and the end surface are sealed, and a corrosion test of Cass 300Hr is performed.
The maximum pitting depth generated in the sample was measured. -Refrigerant side: After applying the same brazing heat as the strength measurement sample, seal the brazing material side and end face, and Cl ^- 195ppm, F
_{^{e 3+ 30ppm, SO 4 2- 60ppm}} , 88 ℃ containing Cu ²⁺ 1 ppm
The maximum pitting depth generated in the sample was measured by performing a cycle immersion test of 8 hours in high temperature water and 16 hours left at room temperature for 3 months.

[0033]

[Table 1]

[0034]

[Table 2]

[0035]

[Table 3]

[0036]

[Table 4]

As is apparent from Tables 3 and 4, the invention sample N
o.1 to 24, the strength after brazing is 17 kgf / mm ² or more and 3003
It is higher than the conventional example No. 35, which uses an alloy core material, has a brazing joint ratio of 90% or more, and has good corrosion resistance. On the other hand, Comparative Examples No. 26, 28, 29, 30, 31, 32 have lower strength than the inventive examples. Comparative Examples No. 25, 27, 33, 34 have high strength,
The brazing and welding rate is as low as 55% or less, and the corrosion resistance is poor. Also,
Comparative Examples No. 28, 29, 31, 32 have a high brazing joint ratio and are excellent in brazing property, but the strength is less than 17 kgf / mm ^2, which is lower than the inventive examples. Further, the conventional example No. 35 in which the core material is a single layer of 3003 alloy is excellent in brazing property, but is low in strength. Therefore, the aluminum brazing sheet according to the present invention,
Each property can be improved while maintaining the balance of strength, brazing property, and corrosion resistance as compared with conventional materials.

[0038]

As described above, according to the present invention, the strength after brazing is high, the corrosion resistance on both the atmosphere side and the refrigerant side is good, and
In addition, an aluminum brazing sheet having a good brazing property can be obtained, which makes it possible to reduce the thickness of the heat exchanger member and has a remarkable effect on the weight reduction of the automobile.

[Brief description of drawings]

FIG. 1 is an explanatory view showing a structure of a vehicle radiator.

FIG. 2 is a perspective view showing a brazing heat core for determining the brazing property of an aluminum brazing sheet.

[Explanation of symbols]

 1 tube 2 fins 3 header 4 tank 5 sample

Claims (4)

[Claims] 1. A brazing material of an Al-Si alloy on one surface of the core material, and an Al-Zn alloy or Al-Zn-M on the other surface.
In an aluminum brazing sheet in which a sacrificial anode material such as a g-based alloy is clad, the core material has a two-layer structure, and the layer on the brazing material side of the core material has Mn: 0.5 to 1.5 wt% and Cu: 0.5.
-1.0 wt%, Si: 0.5-1.0 wt%, Mg: 0.2 wt% or less, Al consisting of the balance Al and unavoidable impurities
An alloy, the layer on the side of the sacrificial anode material is Si: 0.3 to 1.0 wt%,
An Al alloy containing Mg: 0.5 to 1.5 wt% and Cu: 0.1 to 1.0 wt%, the balance being Al and unavoidable impurities, and the thickness of the layer on the brazing material side of the core material having a two-layer structure core An aluminum brazing sheet characterized by exceeding 50% of the total thickness of the material. 2. A brazing material of an Al--Si alloy on one surface of the core material, and an Al--Zn alloy or Al--Zn-M on the other surface.
In an aluminum brazing sheet in which a sacrificial anode material such as a g-based alloy is clad, the core material has a two-layer structure, and the layer on the brazing material side of the core material has Mn: 0.5 to 1.5 wt% and Cu: 0.5.
.About.1.0 wt%, Si: 0.5 to 1.0 wt%, Mg: 0.2 wt% or less, and each of 0.05 to 0.3 wt% Cr, Zr,
An Al alloy containing one or more of Ti and the balance Al and unavoidable impurities is used, and the layer on the side of the sacrificial anode material is Si: 0.3 to 1.0 wt%, Mg: 0.5 to 1.5 wt%, C
u: An Al alloy containing 0.1 to 1.0 wt% and the balance Al and unavoidable impurities, and the thickness of the layer on the brazing material side of the core material is 50% of the total thickness of the two-layer structure core material. Aluminum brazing sheet characterized by exceeding. 3. A brazing material of an Al--Si alloy on one surface of the core material, and an Al--Zn alloy or Al--Zn-M on the other surface.
In an aluminum brazing sheet in which a sacrificial anode material such as a g-based alloy is clad, the core material has a two-layer structure, and the layer on the brazing material side of the core material has Mn: 0.5 to 1.5 wt% and Cu: 0.5.
-1.0 wt%, Si: 0.5-1.0 wt%, Mg: 0.2 wt% or less, Al consisting of the balance Al and unavoidable impurities
An alloy, the layer on the side of the sacrificial anode material is Si: 0.3 to 1.0 wt%,
Mg: 0.5 to 1.5 wt%, Cu: 0.1 to 1.0 wt%, and 0.05 to 0.3 wt% of Mn, Cr, Zr, and T, respectively.
i is an Al alloy containing one or more of i and the balance Al and inevitable impurities, and the thickness of the layer on the brazing material side of the core material is equal to the thickness of the entire two-layer structure core material. Aluminum brazing sheet characterized by exceeding 50%. 4. A brazing material of an Al-Si alloy on one surface of the core material, and an Al-Zn alloy or Al-Zn-M on the other surface.
In an aluminum brazing sheet in which a sacrificial anode material such as a g-based alloy is clad, the core material has a two-layer structure, and the layer on the brazing material side of the core material has Mn: 0.5 to 1.5 wt% and Cu: 0.5.
.About.1.0 wt%, Si: 0.5 to 1.0 wt%, Mg: 0.2 wt% or less, and each of 0.05 to 0.3 wt% Cr, Zr,
An Al alloy containing one or more of Ti and the balance Al and unavoidable impurities is used, and the layer on the side of the sacrificial anode material is Si: 0.3 to 1.0 wt%, Mg: 0.5 to 1.5 wt%, C
u: 0.1-1.0 wt%, each 0.05-0.3 wt%
% Of Mn, Cr, Zr, and Ti, which is an Al alloy containing one or more of Mn, Cr, Zr, and Ti, and the balance Al and unavoidable impurities, and the thickness of the layer on the brazing material side of the core material is two layers. An aluminum brazing sheet characterized by exceeding 50% of the total thickness of the structural core material.