JPH079123A - Brazing method for mg-containing aluminum alloy material - Google Patents

Abstract

PURPOSE:To provide the brazing method for an Mg-contg. aluminum alloy material capable of executing excellent brazing by suppressing the reaction of Mg and flux in brazing of the Mg-contg. aluminum alloy using a fluoride flux. CONSTITUTION:A flux contg. Al alloy brazing filler metal 2 which is compounded with a brazing filler metal component having <=580 deg.C liquidus line temp. and a fluoride flux component having <=560 deg.C liuqidus line temp. at 95:5 to 70 to 30 by weight and has the density of R->=90% with supect to the theretical value is arranged in part 1, 1 to be joined and is heated to braze the aluminum alloy material contg. >1.5wt. <=6.0wt.% Mg at the time of brazing this alloy material.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a brazing method of a Mg-containing aluminum alloy material which is applied to brazing of heat exchangers and joints for automobiles.

[0002]

2. Description of the Related Art Since Mg-containing aluminum alloy materials have high strength, they are widely used as materials for various aluminum products which require strength. The brazing of such an Mg-containing aluminum alloy material is performed by applying a general flux brazing method in which the flux suspension is applied to the aluminum material to be joined and the brazing material is supplied and heated to a predetermined temperature. There is. Further, as the flux,
In addition to chloride-based flux, non-corrosive fluoride-based flux is widely used.

[0003]

However, since the Mg-containing aluminum alloy material is inferior in brazing property, in particular, brazing property using a non-corrosive fluoride-based flux, an evaporator for automobile radiators and car coolers. However, there was a limit to the application as a material for brazing products such as capacitors.

That is, in the brazing method as described above, since a large amount of flux adheres to the surface of the aluminum material, F in the flux reacts with Mg in aluminum at a temperature before the brazing material begins to melt. As a result, a compound such as MgF ₂ is formed on the surface of the aluminum material. It is considered that this hinders the wetting and spreading of the brazing material, and as a result, sufficient brazing cannot be performed, which has been a cause of hindering the expansion of application of the Mg-containing aluminum material to brazing products. . In particular, in an aluminum alloy material containing Mg in excess of 1.5 wt%, the influence of brazing failure due to the Mg-F compound is large.

In order to solve the above problems, the present invention is excellent in brazing of a Mg-containing aluminum alloy material using a fluoride type flux by suppressing the reaction between Mg and the flux. Mg that can be attached
An object of the present invention is to provide a brazing method for a contained aluminum alloy material.

[0006]

In order to achieve the above object, the method for brazing an Mg-containing aluminum alloy material of the present invention is an aluminum alloy material containing more than 1.5 wt% and not more than 6.0 wt% Mg. When brazing, the brazing filler metal component having a liquidus temperature of 580 ° C. or less and the fluoride flux component having a liquidus temperature of 560 ° C. or less are 95: 5 by weight ratio.
70 to 30 is mixed, and the density is 90 of the theoretical value.
% Or more of the flux-containing Al alloy brazing material is arranged in the jointed portion and heated for brazing.

The aluminum alloy material which is the object of the brazing method according to the present invention contains Mg in an amount of more than 1.5 wt% and 6.0 wt%.
It is contained in the following range, but as another component, C
It may contain one or more of u, Si, Fe, Zn and the like. However, if the contents of these elements are too large, the melting point of the aluminum alloy material is lowered and brazing becomes difficult, so it is preferable that the solidus temperature does not fall below 550 ° C. The Mg content is 1.5 wt.
% Or less aluminum alloy can be brazed by the method developed by the present applicant (Japanese Patent Application No. 4-153302), and the application of the present invention is not significant. Further, if the Mg content exceeds 6.0 wt%, brazing is difficult even by the present invention because the reaction between Mg and the flux is promoted.

The flux-containing Al alloy brazing material used in the present invention is a mixture of a brazing material component and a flux component in a predetermined ratio.

The brazing filler metal component functions as a brazing filler metal for joining aluminum alloys, and when the melting point of the aluminum alloy brazing material is taken into consideration, the liquidus temperature is 58.
It is necessary to select one having a composition of 0 ° C. or less. Specifically, an Al-Si alloy and an Al-Si-Zn-Cu alloy can be exemplified, and if it is an Al-Si alloy, Al-11 to 12% S.
i-composition, Al-Si-Zn-Cu alloy, Al-0.05 to 15% Si-0.05 to 15% Zn-
The liquidus temperature is 580 ° C for the composition of 0.05 to 5% Cu.
It becomes the following.

Considering that the liquidus temperature of the brazing filler metal component is 580 ° C. or lower, it is necessary to select a fluoride-based flux having a liquidus temperature of 560 ° C. or lower. Specifically, KF-AlF ₃ eutectic composition (45.8% KF-54.2% AlF 3) and its vicinity composition, or if necessary to LiF, CsF, N
An example is one in which aF or the like is added in the range of 0.05 to 15 wt%.

The blending ratio of the flux component in the flux-containing Al alloy brazing material must be set so that the weight ratio of the brazing material component and the flux component is 95: 5 to 70:30. When the amount of flux is less than 95: 5 by weight, sufficient flux action cannot be exhibited and brazing becomes difficult, while when the amount of flux exceeds 70:30, the brazing material component and the flux component are mixed. Then, solidification becomes difficult, and it becomes difficult to manufacture the flux-containing Al alloy brazing material itself. The preferable mixing ratio of the brazing material component and the flux component is 90: 1 by weight.
0 to 75:25, and particularly preferably 85: by weight.
3 to 78:22.

The method for producing the flux-containing Al alloy brazing material used in the present invention is not particularly limited, but in general, the brazing material component powder such as Al powder, Si powder, Zn powder, Cu powder and the flux component are used. It is manufactured by mixing powder and pressing and solidifying by hot pressing or the like. Thus, due to the residual internal air, the density of the flux-containing Al alloy brazing material is generally smaller than the theoretical value calculated from the density of each material powder. Therefore, in the present invention, the density of the brazing material must be 90% or more of the theoretical value. If the density of the brazing filler metal is less than 90% of the theoretical value, the brazing filler metal component and the flux are solidified, but there is a risk that the pores are connected to the inside and become brittle, and subsequent secondary processing is also difficult. In fact, the function as a brazing material is also inferior. Particularly preferably, the density of the brazing material is 95% or more of the theoretical value.

A preferred specific method for producing such a flux-containing Al alloy brazing material will be described below.
That is, first, brazing material powders such as Al and Si and flux powders are prepared as starting materials. In order to achieve uniform mixing of these powders, for example, Al powder has an average particle size of 44μ.
It is preferable that the Si powder has an average particle diameter of 5 μm or less and the flux powder has an average particle diameter of 30 μm or less. The starting material is not necessarily Al,
It is not necessary to use Si etc. alone, but A
You may use it in the form of the powder of 1-Si type alloy.

After mixing the above powders so as to have the above-mentioned predetermined mixing ratio, the mixture is filled in a container such as an Al can, the inside of the container is degassed to 1 mmHg or less, and then heated by a hot press or the like. To powder. Next, after removing the outer can body of the obtained thermocompression-molded body by cutting, the molded body is subjected to secondary processing such as extrusion to obtain a desired brazing material.

The Mg-containing aluminum alloy material is brazed using the flux-containing Al alloy brazing material manufactured in this manner by a conventional method such as torch brazing or atmospheric heating.

[0016]

In brazing, the flux-containing Al alloy brazing material is placed on the joined portion of the Mg-containing aluminum alloy material and heated. Since the flux is contained in the brazing material, the flux does not elute until the temperature at which the brazing material begins to melt, the reaction between F in the flux and Mg in the Mg-containing aluminum alloy material is avoided, and the brazing material melts. It is speculated that the flux will exert its effect once it is started.
As a result, it is presumed that the brazing material spreads before the flux action and the wetting and spreading of the brazing material proceed at the same time and the flux and Mg react, and good brazing is achieved.

[0017]

EXAMPLES Next, specific examples of the brazing method for the Mg-containing aluminum alloy material of the present invention will be described with reference to the drawings.

First, a flux-containing Al alloy brazing material was manufactured by the following material powder and method.

As a brazing filler metal component, Al having a purity of 99.5%
Powder (average particle size 44 μm), Si powder (average particle size 5 μm
m), Zn powder (average particle size 44 μm) and Cu powder (average particle size 44 μm) as flux components.
5.8% KF-54.2% AlF ₃ eutectic powder (average particle size 30 μm), KF powder (average particle size 30 μm), AlF ₃
Powder (average particle size 30 μm), CsF powder (average particle size 30
μm) and LiF powder (average particle size 44 μm) were prepared.

Each of the above powders was designated as No. 1 in Table 1 below. 1 to
The mixing ratio was changed so that each ratio as shown in 10 was obtained, and the mixture was uniformly mixed at room temperature to prepare a mixed powder. The liquidus temperatures of the brazing filler metal component and the flux component of each mixed powder are as shown in Table 1.

Each of the above-mentioned mixed powders has a diameter of 3 inches and a length of 2
Fill each 00mm Al can in the air and
The can was placed in a furnace at 500 ° C., and the inside of the Al can was vacuum degassed to 1 mmHg or less. After that, the Al can was heated to 480 ° C., and then hot-pressed using a hot press at a maximum pressure of 400 tons, and the length of the formed product was 110 mm. Further, after removing the Al can body adhering to the outside of the molded body by cutting, it was extruded by a hot extruder at a temperature of 500 ° C. into a flat plate having a thickness of 1 mm and a width of 30 mm. The applicability of extrusion molding at that time is shown in Table 1. Further, when the density of extrudable ones was calculated and compared with the theoretical density calculated based on the starting materials, they were all dense with 98% or more of the theoretical value.

Then, No. 3 was satisfactorily extruded. 1-6,
For Nos. 8 and 9, the brazing property was evaluated according to the procedure shown in FIG.

A solidus temperature of 5 is applied to the joining members (1) and (1).
Al-5wt% Mg alloy at 78 ° C, width 30mm x length 10
A 0 mm × 1 mm thick flat plate was used, and the flux-containing Al alloy brazing material (2) was cut into a width of 30 mm × a length of 30 mm × a thickness of 1 mm. Then, the end portions of the joining members (1) and (1) are superposed at a superposition margin of 30 mm in a state in which the flux-containing Al alloy brazing material (2) is interposed between them, and the superposed portion is formed. A cylindrical body made of SUS304 and having a diameter of 30 mm (3)
The cylindrical body (3) was heated by a nichrome heater (4) while being sandwiched between (3) and pressurized. With such a heating device, the joining member (1) is brazed under the conditions of a heating temperature of 1000 ° C., a pressing force of 10 kgf and a pressing time of 10 seconds,
The state of the joint was observed to evaluate the brazing property.

Further, in Comparative Example No. 11, the same heating device was used to replace the flux-containing Al alloy brazing filler metal (2) with an A4045 Al alloy (Si content 1
0wt%) on both sides of 45.8% KF-54.2% AlF ₃
Use the one with the suspension applied, heating temperature 1000 ° C,
The joining member (1) was brazed under the conditions of a pressing force of 10 kgf and a pressing time of 15 seconds.

The results are shown in Table 1.

[0026]

[Table 1] From the results shown in Table 1, it was confirmed that according to the present invention, brazing of the Mg-containing Al alloy material using the fluoride-based flux can be satisfactorily performed. On the other hand, No. 1 having a high liquidus temperature of the brazing filler metal component. No. 3 has a poor brazing property due to insufficient melting of the brazing material and has a small amount of flux. 6 Mouro's wetness was bad. Also, N with a large amount of flux
o. No. 7 with a small amount of Al in the brazing filler metal component. 10
Was unable to evaluate the brazing property because the flux was broken during extrusion. Furthermore, N coated with flux
o. In No. 11, the fillet was non-uniform even after 15 seconds of brazing, and the joining member (1) also partially melted at the grain boundaries.

[0027]

As described above, in the brazing method of the Mg-containing aluminum alloy material of the present invention, the liquidus temperature is 58.
The brazing filler metal component having a temperature of 0 ° C. or less and the fluoride flux component having a liquidus temperature of 560 ° C. or less are 95: 5 to 70 by weight ratio.
In addition, since a flux-containing Al alloy brazing material having a density of 90% or more of the theoretical value is used,
An aluminum alloy material containing Mg in an amount of more than 1.5 wt% and 6.0 wt% or less can be brazed extremely well, and the application and expansion of the Mg-containing aluminum alloy material to a brazed product can be achieved. .

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a brazing method in this embodiment.

[Explanation of symbols]

 1 ... Joining member 2 ... Flux-containing Al alloy brazing material 3 ... Cylindrical body 4 ... Nichrome heater

Claims (1)

[Claims] 1. A Mg content of more than 1.5 wt% and 6.0 wt% or less.
When brazing an aluminum alloy material containing Al, a brazing filler metal component having a liquidus temperature of 580 ° C. or lower and a fluoride flux component having a liquidus temperature of 560 ° C. or lower are 95: 5 by weight ratio. A Mg-containing aluminum alloy material, characterized in that a flux-containing Al alloy brazing material having a density of 90% or more of a theoretical value is blended in 70 to 30 and placed in a joined portion and heated for brazing. Brazing method.