JPH04263035A - High strength clad aluminum alloy material for low temperature brazing - Google Patents

Abstract

PURPOSE:To provide a high strength clad aluminum alloy material for low temp. brazing used, as a heat exchanger member, e.g. for brazing at <=500 deg.C in automobile, and having high strength and also corrosion resistance equal to or higher than that of the conventional material. CONSTITUTION:At least one side of an aluminum alloy material, which has a composition containing, by weight, 2.0-9.5% Zn or one or two kinds among 2.0-9.5% Zn, 0.03-4.5% Mg, and 0.03-3.5% Cu, further containing one or >=2 kinds among 0.01-0.35% Cr, 0.01-1.8% Mn, 0.01-0.35% Zr, 0.03-0.5% Hf, 0.03-0.35% V, 0.03-3.5% Ni, 0.02-1.5% Fe, and 0.005-0.35% Ti, and having the balance Al with inevitable impurities, is coated with a brazing filler metal melting at <=500 deg.C, or one side of the aluminum alloy material is clad with a sacrificial material and the opposite side of the sacrificial material is clad with the brazing filler metal.

Description

[Detailed description of the invention]

0001

[Field of Industrial Application] The present invention relates to a high-strength aluminum alloy clad material for low-temperature brazing that is brazed at a temperature of 500°C or less, and in particular is used as a heat exchanger member for automobiles. It is suitable for

0002

[Prior Art] Most heat exchangers for automobiles are made of Al and A.
l alloy is used and manufactured by brazing method. Usually, an Al-Si based brazing material is used for brazing, and therefore brazing is performed at a high temperature of about 600°C. In brazing using Al-Si brazing filler metal, the filler metal may be supplied by powder, wire, or plate material, but generally speaking, in consideration of workability, the brazing filler metal is hot-heated as a core material. This is often done using a so-called brazing sheet that is clad by crimping. For example, JIS A 3003 (Al-0.15
The core material is JIS A 7072 (Al-1 wt% Zn), and the other side is JIS A 4343 (Al-7.
A brazing sheet composed of a brazing filler metal of 5 wt% Si) is used.

[0003] In recent years, in order to reduce brazing costs, there has been an increasing demand for lower brazing temperatures. By lowering the brazing temperature, there are various advantages such as reducing brazing time, reducing the amount of heat, reducing the cost of the brazing furnace, improving the durability of the brazing furnace, and being able to use almost any Al material. to be born. The low-temperature brazing method that is currently in practical use involves applying a mixture of Zn powder and ZnCl2-based flux to a core assembled from Al material, and heating and brazing it to about 450°C to melt the Zn. Are known.

0004

[Problems to be Solved by the Invention] In recent years, due to environmental issues, there has been a demand for lighter vehicle weights due to the demand for improved fuel efficiency of automobiles, and a trend towards larger heat exchangers due to changes in refrigerants due to the ban on the use of certain fluorocarbons. There is an urgent need to reduce the weight of heat exchangers or reduce the weight increase by making the exchanger members thinner. However, in heat exchanger parts brazed using conventional Al-Si brazing filler metal, as mentioned above,
Since it is exposed to high temperatures of around 100°C, only materials with high melting points can be used, and there is a limit to how high the strength of the parts can be increased.

[0005] Furthermore, in the case of low-temperature brazing of conventional pure Al alloys such as 1000 series with Zn alloy brazing,
In some cases, Zn solder diffused into the core material, making brazing difficult.

[0006]

[Means for Solving the Problems] In order to solve the above problems, the present invention has developed a high-strength aluminum alloy cladding material for low-temperature brazing coated with a low-melting-point brazing filler metal, as a result of various studies. be.

That is, one of the aspects of the present invention is that Zn 2.0 to 9.
5 wt% and further contains Cr 0.01 to 0.3
5wt%, Mn 0.01 ~ 1.80wt%, Zr
0.01 to 0.35wt%, Hf0.03 to 0.5
wt%, V0.03-0.35wt%, Ni 0.03
~3.5 wt%, Fe 0.02 ~1.5 wt
%, Ti 0.005 to 0.35 wt% on at least one side of an aluminum alloy material containing one or more of 0.005 to 0.35 wt%, the balance being Al and inevitable impurities.
It is characterized by being coated with a brazing material that melts at temperatures below 0° C. It is preferable to use a plate material in which one side of an aluminum alloy material is clad with a sacrificial material, and the other side of the sacrificial material is coated with a brazing material.

Another aspect of the present invention is Zn 2.0 to 9.
5 wt%, Mg 0.03 to 4.5 wt%, C
Contains one or two of u 0.03 to 3.5 wt%, and further contains Cr 0.01 to 0.35 wt%,
Mn 0.01 ~ 1.80wt%, Zr 0.01
~0.35 wt%, Hf 0.03 ~0.5 wt%
, V 0.03 ~ 0.35 wt%, Ni 0.03 ~ 3
．． 5 wt%, Fe 0.02 ~ 1.5 wt%, T
i An aluminum alloy material containing one or more of 0.005 to 0.35 wt%, with the remainder being Al and unavoidable impurities, is coated on at least one side with a brazing filler metal that melts at 500°C or below. It is preferable to use a plate material in which one side of an aluminum alloy material is clad with a sacrificial material, and the opposite side of the sacrificial material is coated with a brazing material.

[0009]

[Operation] The reason for defining the alloy composition as described above in the present invention is as follows. Zn has the effect of increasing the strength of the material, and when performing low-temperature brazing using Zn brazing, it has the effect of suppressing the diffusion of Zn alloy brazing into the core material and preventing brazing defects. be. However, 2.5
If the content is less than wt% (hereinafter wt% is abbreviated as %), these effects will not be sufficient, and if it is added in excess of 9.5%, corrosion resistance will decrease. Mg and Cu form fine precipitates together with Zn and contribute to improving the strength. However, if each element is below the lower limit, it cannot be expected to contribute much to the strength, and if added above the upper limit, the corrosion resistance will deteriorate significantly. Cr,Mn
, Zr, Hf, V, Ni, Fe, and Ti all have the effect of improving the strength of the material, especially high-temperature strength, and preventing deformation during and after brazing. Therefore, it is generally preferable to add a predetermined amount of one or more of these elements. However, on the other hand, the addition of these elements refines the material structure of the material, increases the grain boundary area, promotes diffusion of the filler metal, and has the risk of deteriorating corrosion resistance. It is necessary to determine the amount of addition based on the part of the product where it will be used. However, if the amount added is less than the lower limit, the above-mentioned effects cannot be expected, and if the amount added exceeds the upper limit, coarse compounds will be generated in the material, resulting in poor formability, strength, and toughness of the material.
There is a risk that both corrosion resistance will deteriorate. Impurities other than the above elements are mainly Si, and Si is 0.4
If it is less than %, it will not adversely affect the characteristics of the present invention, but
If the content is 0.4% or more, the strength will decrease. Further, if the content of other trace elements is 0.05% or less, the properties of the material of the present invention are not adversely affected. Therefore, it is possible to add B, Be, etc. to improve castability, etc., or misch metal, etc. to improve moldability, within a range of 0.05% or less.

As the brazing material, any alloy having a melting point of 500° C. or lower, such as pure Zn, Zn-Al series, Zn-Cd series, Sn-Zn series, Sn-Pb series, etc., can be used. However, when considering the corrosion resistance of the product after brazing, a Zn alloy brazing material has the widest applicability. The brazing material may be coated by any method such as hot pressing, thermal spraying, hot-dip plating, electroplating, or vapor deposition. However, industrial economic efficiency (
In consideration of coating cost and productivity, it is preferable to coat by hot pressing or plating. The coating thickness of the wax is not particularly limited, and may be determined depending on the shape of the product and the area where it will be used. Currently, as shown in Figure 1, fins (2
) and headers (3) at both ends of the liquid pipe (1).
When a part of the component is exposed to a corrosive environment, such as the brazing sheet used as the liquid passage pipe (1) of a radiator equipped with Generally, the cladding material is a low potential material such as JIS A 7072 alloy. Therefore, in the present invention, it is also possible to use an alloy that is 50 mV or more less noble than the potential of the core material alloy as a sacrificial material on one side of the core material (the opposite surface to the brazing material). It is also possible to further clad another alloy layer between the core material and the brazing material or between the core material and the sacrificial material for the purpose of improving corrosion resistance. When further cladding an alloy layer between the core material and the sacrificial layer, the potential of the sacrificial material must be 50 mV or more less base than the potential of the alloy layer, and the potential of the sacrificial material must be 50 mV or more less base than that of the core material. It is preferable that the base voltage is 50 mV or more.

[0011]

[Examples] The present invention will be explained below with reference to Examples. (Example 1) The alloy shown in Table 1 was cast to a thickness of 4 by DC casting.
The ingot was made into a 00 mm x width 2300 mm ingot, which was homogenized (440° C. x 12 hours + 520° C. x 12 hours), and then hot-rolled and cold-rolled into a test plate with a thickness of 1 mm. As shown in Figure 2, a device was installed on one side of each of these test plates to pass the plate (4) through a brazing bath (6) along guide rollers (5) to hot-dip a brazing metal on one side of the plate (4). Zn-5%Al alloy with a thickness of 30 μm
Plated to a thickness of . These materials were brazed and simulated heated to a temperature of 450°C with a dew point of -40°C.
It was inserted into a furnace with a nitrogen gas atmosphere to perform brazing heating, and after heating, it was taken out from the furnace and cooled in air. Tensile test pieces were fabricated from these plates and tensile tests were conducted. The results are also listed in Table 1.

Furthermore, as shown in FIG. 3, these plated plates (7) were vertically erected on the bare material (8) to form an inverted T-joint test piece, and LiCl, KCl, ZnCl
A 50% concentration liquid of chloride flux consisting of 2 or the like was applied and brazed at a temperature of 420°C to evaluate the brazing properties. The results are also listed in Table 1, with ○ indicating that a normal fillet was formed and × indicating that there was a portion where no fillet was formed.

[0013]

[Table 1]

As is clear from Table 1, the material of the present invention has higher strength than comparative materials outside the scope of the present invention or conventional materials, and also forms a normal fillet, so that it can be used satisfactorily as a brazing material. I understand.

(Example 2) In the structure shown in Table 2, one side of the core material was clad with a sacrificial material at a ratio of 10% to a thickness of 1.
A 2 mm plate was manufactured by a conventional hot pressing method. Using this plate material, Zn-
A 11% Al (melting point: 425° C.) brazing material was plated to a thickness of 80 μm on the opposite side to the sacrificial material. After degreasing these, a 10% concentration solution of fluoride flux with basic composition of AlF3 and CsF was applied, and the pieces were inserted into a furnace with a nitrogen gas atmosphere at a temperature of 450°C and a dew point of -40°C to perform brazing heating. went. A tensile test piece was processed from the material after heating and a tensile test was performed to evaluate the mechanical properties.
Cut out a test piece of m x length 100mm, seal it except for the sacrificial layer side, and check the corrosion resistance from the sacrificial layer side by CASS.
Test Evaluation was performed by a 720 hour corrosion test. The evaluation was based on the maximum pitting depth after the corrosion test. The results are shown in Table 2.

[0016]

[Table 2]

As is clear from Table 2, the material of the present invention not only has excellent strength, but also exhibits properties equivalent to or better than conventional materials in terms of corrosion resistance.

[0018]

As described above, according to the present invention, it is possible to supply a brazing member for a heat exchanger that has significantly higher strength than conventional materials for low-temperature brazing and has corrosion resistance higher than that of conventional materials. It has remarkable industrial effects, such as making it possible to

[Brief explanation of the drawing]

FIG. 1 is a partially cutaway perspective view of an example of a radiator.

FIG. 2 is an explanatory diagram showing a hot-dip plating apparatus.

FIG. 3 is a perspective view showing an inverted T-joint test piece.

[Explanation of symbols]

1 Liquid passage pipe 2 Fin 3 Header 4 Plate material 5 Guide roller 6. Brazing bath 7 Brazing plate 8 Bare material

Claims (4)

[Claims] Claim 1: Contains 2.0 to 9.5 wt% of Zn, further contains 0.01 to 0.35 wt% of Cr, and Mn 0
．． 01 ~1.80wt%, Zr 0.01 ~0.3
5wt%, Hf0.03-0.5wt%, V 0.03
~0.35 wt%, Ni 0.03 ~3.5 wt
%, Fe 0.02 to 1.5 wt%, Ti 0.0
An aluminum alloy material containing one or more of 05 to 0.35 wt%, the remainder being Al and inevitable impurities, is coated on at least one side with a brazing filler metal that melts at 500°C or less. High strength aluminum alloy clad material for low temperature brazing. 2. The high-strength aluminum alloy clad material for low-temperature brazing according to claim 1, wherein a plate material is used in which one side of the aluminum alloy material is clad with a sacrificial material, and the opposite side of the sacrificial material is coated with a brazing material. [Claim 3] Zn 2.0 to 9.5 wt% and M
g 0.03 ~ 4.5 wt%, Cu 0.03 ~
Contains one or two of 3.5 wt%, and further contains Cr 0.01 to 0.35 wt%, Mn 0.01 to 1
．． 80wt%, Zr 0.01 ~ 0.35wt%, H
f 0.03 ~ 0.5 wt%, V 0.03 ~ 0
．． 35 wt%, Ni 0.03 to 3.5 wt%, F
e 0.02 ~ 1.5 wt%, Ti 0.005 ~
A low-temperature material comprising an aluminum alloy material containing one or more of 0.35 wt% and the remainder being Al and inevitable impurities, and coated on at least one side with a brazing filler metal that melts at 500 °C or less. High strength aluminum alloy cladding material for brazing. 4. The high-strength aluminum alloy clad material for low-temperature brazing according to claim 3, wherein a plate material is used in which one side of the aluminum alloy material is clad with a sacrificial material, and the opposite side of the sacrificial material is coated with a brazing material.