JPH03243294A - Brazing method for high-strength al alloy, high-strength al alloy for brazing structure and high-strength al alloy brazing sheet - Google Patents

Abstract

PURPOSE:To make improvement in the quality of the Al alloy brazed joint having a specific compsn. by providing an Al alloy coating layer having a specific compsn. and thickness on the surface of a material to be brazed and brazing the material. CONSTITUTION:The Al alloy coating layer having <0.5wt.% Mg content is previously provided at >=100mum thickness on the brazing surface and the brazing of the high-strength Al alloy is executed by melting the brazing material in the brazing of the high-strength Al alloy contg. <2.0wt.% Cu, <1.2wt.% Si and 0.3 to 5.6wt.% Mg. The characteristic of high strength is obtd. by using the Mg-contg. Al alloy in this way and the good brazing characteristic is assured.

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention provides high-strength Ai! , a brazing method in which an appropriate fillet is formed in the brazing metal part and good brazing bondability is obtained when brazing the alloy, and a structural Al alloy material and plate used in this brazing method. This is related to the ging sheet.

[Prior Art] When joining parts made of pure Al or Al alloy, if the parts have a complicated shape, are relatively thin, or have many joining points, joining by brazing is recommended. The method is widely used.

To give a concrete example, the brazing filler metal is JI
An Al alloy with good brazing properties, such as S4104 and JIS4343, is used, and this brazing material is supplied to the plating sheet or to the brazing part to be placed.

The parts are assembled according to the shape of the product, and together with the plating sheet and the placeholder, they form an assembly. The assembly is placed in an air or inert gas atmosphere furnace after application of flux, or placed in a vacuum furnace without application of flux. In the furnace, the temperature is maintained at a temperature higher than the melting temperature of the brazing material (for example, approximately 600° C. for an Al-Si alloy brazing material) to melt the brazing material and perform brazing.

By the way, Al is used for various purposes taking advantage of its light weight, and brazed products joined by brazing are also widely applied to honeycomb structures (for example, the swing arms of motorcycles) and heat exchangers, and are used for strength and strength. Al2 alloys are often used because they have excellent brazing properties, even if they are slightly low.

However, recently, in order to expand the use of Al alloys, there has been a demand for the use of structural If alloys that have high strength and excellent brazing properties.

Furthermore, the strength of the entire brazed product is affected not only by the strength of the structural Al alloy but also by the strength of the plating sheet that forms part of the product structure. However, the Al2-Mn alloy that has been conventionally used as the core material of plating sheets does not have sufficient strength, which is one of the causes of lowering the breaking strength of brazed products. For this reason, it is desired to use a high-strength Al alloy with excellent brazing properties also for the core material of the plating sheet.

[Problem to be solved by the invention] Generally, high-strength Al alloys include JIS 200O series, 5
000 yarn, 6000 series, and 7000 series alloys are known. However, 2000 series and 6000 series alloys have Cu,
Since it contains a relatively large amount of Si and has a low melting temperature, it has the problem of being melted for brazing. Furthermore, the alloy is in an annealed state due to the heating during brazing, and the rate of melting at the brazed portion is not high, so an appropriate hardening effect cannot be obtained and the strength is insufficient. Furthermore, sufficient strength cannot be obtained by subsequent heat treatment.

Therefore, JIS 2000 series and 6000 series Al alloys are unsuitable as high-strength materials for brazing.

From the above points, as a high strength Al alloy for brazing, M
Possible candidates include a 7000 series alloy that contains a relatively large amount of g and has low quenching sensitivity, and a non-heat-treated 5000 series alloy.

However, when 5000 series and 7000 series A1 alloys are used, there is a problem in that an appropriate fillet is not formed in the brazed part, resulting in poor brazing performance (hereinafter referred to as brazing performance). .

In order to solve the above problems, the present inventors have developed Mg-containing A
We investigated and researched the causes of poor brazing properties in l-gold alloys and found that the following two factors were the causes.

The first point is that Mg-containing A1 gold alloys tend to form a fine, isotropic recrystallized structure by annealing, and are susceptible to grain boundary erosion by molten solder. In addition, the molten solder that has entered (for example, 8β-3i solder) incorporates Mg that diffuses into the Al alloy, thereby lowering its melting point, so that it continues to stably erode the grain boundaries of the alloy. Therefore, the necessary wax that should contribute to fillet formation is absorbed into the alloy, resulting in insufficient fillet formation and deteriorating brazability.

(2) The second point is that the Mg-containing Hachihe alloy is
Regardless of the atmosphere such as inert gas or air, an oxide film grows thickly on the surface due to annealing or heating during brazing, and the higher the Mg content, the faster the oxide film grows. This film has the effect of promoting excessive expansion of molten solder,
It inhibits fillet formation in the solder part and deteriorates brazing properties.

The penetration of the solder and the spreading of the solder described in (21) become more pronounced as the Mg content of the Al2 alloy increases, further deteriorating the brazing properties.

Therefore, as the AJ2 alloy used for brazing, Mg
The lower the content, the better the brazing properties, but the property of high strength cannot be satisfied.

The present invention is based on the above-mentioned knowledge, and aims to obtain high strength characteristics and ensure good brazing properties using an Mg-containing Al alloy.

[Means for Solving the Problems] In order to achieve the above object, the method of brazing high strength Al alloy of the present invention includes
i content is less than 1.2% by weight, Mg is 0.3-5.6
Prior to brazing the high strength Al alloy containing % by weight,
A coating layer made of pure Al or an Al alloy with an Mg content of less than 0.5% by weight is provided on at least the brazing surface of the high-strength A and 9 alloys with a thickness of 100 μm or more, and the brazing material is melted. This is characterized in that the high-strength Al1 alloy is brazed.

Next, the high-strength Aff alloy material for brazed structures of the second invention has a Cu content of less than 2.0% by weight and a Si content of 1.2% by weight.
At least on the brazing surface of a high-strength Al alloy for brazing structures containing 0.3 to 5.6% by weight of Mg,
The coating layer is characterized in that a coating layer made of Al2 alloy having a Mg content of less than 0.5% by weight is provided with a thickness of 1QOLLm or more.

The third invention, the high-strength Al alloy plating sheet, has a Cu content of less than 2.0% by weight and a Si content of 1.2% by weight.
A high-strength Al alloy containing 0.3 to 5.6% by weight of Mg is used as a core material, and at least the brazing surface of this core material has a pure Al or Mg content of less than 0.5% by weight. A coating layer made of Nohe 4 alloy is provided with a thickness of 1100 LL or more, and the surface of this coating layer is coated with a brazing material.

The configuration of the present invention will be explained in more detail below.

First, the reason for limiting the components of the high-strength Al alloy used in the present invention will be described.

Cu content in high strength Al alloy is less than 2.0% by weight, S
The reason why the i content is less than 1.2% by weight is that if the i content exceeds this content, the melting start temperature of the Al alloy will decrease.
This is because local melting of the Al1 alloy occurs during soldering, resulting in a significant decrease in material strength and the possibility that the product shape cannot be maintained.

In addition, the Mg content was set within the range of 0.3 to 5.6% by weight because if it is less than 0.3% by weight, the Al1 alloy strength is insufficient, whereas if it exceeds 5.6% by weight, the strength of the Al1 alloy is insufficient. This is because wax penetration and Al1 alloy melting phenomena occur. In addition, for the same reason, the Mg content was further increased from 0.6 to 3.0.
Preferably, it is limited to % by weight.

In addition, since other components are not mentioned, it is possible to contain appropriate amounts of components other than those mentioned above.

This high-strength Al1 alloy can be used as a structural He4 alloy material, as in the second invention, and furthermore, as in the third invention, it can be used as a core material for bending sheets. .

Next, at least the brazing surface of the above-mentioned high-strength Al alloy is provided with a coating layer made of pure A.degree. C. or Al2 alloy, which will be described later. That is, it is sufficient that at least the coating layer is provided on the surface area where the brazing material is expected to melt and spread. Further, in the present invention, the coating layer may be provided on the alloy surface other than the brazing surface, and it is also conceivable to provide the coating layer not only on one side but also on both sides.

The material used for this coating layer is limited to pure Al or an A,9 alloy with a Mg content of less than 0.5% by weight. Note that pure AJ2 may contain unavoidable impurities. Further, regarding the Al1 alloy, there are no particular limitations on the components other than Mg. The reason why the material of the coating layer is limited to the above is because, according to this composition, the growth of the oxide film on the high-strength 8β alloy surface is slow during brazing heating, and
This is because it is difficult for solder to penetrate into the high-strength Al alloy.

In addition, the reason why the thickness of the above-mentioned coating layer was set to be 1001.1 m or more is that under general brazing conditions, Mg diffusion is 150 um, and in order to effectively eliminate the negative influence of Mg on brazability, it is necessary to minimize the This is because the above thickness is required. There is no particular upper limit to the thickness of the coating layer, but it should not be excessively thick so that the overall strength of the material provided with the coating layer does not decrease due to the presence of the coating layer, which has relatively low strength. is desirable. For example, for a pure A°C coating layer, it is desirable that the thickness be 300 LLm or less.

Note that the method for forming the coating layer is not particularly limited, and a cladding method, a metal spraying method, or the like can be adopted. Generally, the coating layer can be efficiently provided by the cladding method.

When a high-strength β alloy provided with a coating layer as described above is used as a core material of a plating sheet, the surface of the coating layer is further coated with a brazing material. As with the above-mentioned coating layer, the coating method for coating the brazing material is not limited, but
Cladding method is preferred. As for the material of the brazing filler metal, it is desirable that the Mg content is 0.3% by weight or less so that penetration of the brazing filler metal into the high-strength Al alloy is suppressed.

On the other hand, when used as a structural A12 alloy material, the brazing filler metal is supplied by a method such as plating sheet or placing wax, but the method is not particularly limited.

Brazing is performed using the above-mentioned plating sheet and structural Al alloy material by melting a brazing material in various atmospheres in a conventional manner.

In addition, when vacuum brazing is performed with the Mg content of the brazing material of the plating sheet being 0.3% by weight or less as described above, it is best to perform it under a high vacuum of 5 X 10-' Torr or less. desirable. Conventionally, Mg-containing brazing materials increased the corrosion resistance of the plating sheet and suppressed the formation of an oxide film on the core material, but brazing materials with a low Mg content suppressed the formation of an oxide film on the core material. This is because a higher degree of vacuum is desirable.

[Function] That is, according to the present invention, high strength A is achieved during brazing.
At least the brazed surface of the l-alloy is covered with a coating layer, which prevents molten solder from penetrating into the high-strength Al alloy, and further prevents the Mg component in the high-strength Al alloy from diffusing and melting. Prevents chemical reactions with wax. Also, Mg
Suppresses the growth of oxide film caused by the ingredients and does not promote the spread of wax more than necessary.

Therefore, the molten brazing filler metal does not penetrate into the high-strength Al alloy, but spreads appropriately over the brazing surface, forming an appropriate fillet in the brazing section, and achieving a good brazed joint.

An example of the present invention will be described below regarding a case where two Al2 alloy plates are joined by brazing.

[Example 1] In Example 1, a high-strength Al alloy containing Mg was used for one of the Af1 alloy plate materials, and an Al-3i-based Al alloy was used for the other plate material.
l alloy was used.

As high-strength Al alloys, alloys (Nos. 1 to 4) having the compositions shown in Table 1 were produced by ordinary melting and casting methods, and after homogenization heat treatment and surface milling, they were shown in Figure 1 (A). As shown, each alloy l has a pure A℃ consisting of Al and inevitable impurities.
The material was clad by hot rolling to provide a coating layer 2, and then cold rolled to form a 2 mm thick plate material, each of which was annealed to obtain a structural high strength A12 alloy material of the present invention. The thickness of pure Al in each plate material, that is, the thickness of the coating layer 2, is as shown in Table 1.

For comparison, alloy (No. 3) was used, and after the above-mentioned facing, hot rolling and cold rolling were performed to a thickness of 2 mm, and further annealing was performed to prepare a structural plate material of a comparative example without a coating layer. I got it.

The other plate to be joined to the structural plate includes Al1-
Using a /'I2-3i alloy of 1.0 wt% Mn-1.0 wt% Si-(1.5 wt% Cu), this alloy was used as the core material 3 as shown in Fig. 1(B). , on both sides, J
Brazing material 4 made of IS4104 alloy or 4343 alloy
0.5mm thick Al1-5 by cladding with 10% thickness
It was made into an i-type plate material (plating sheet) and further annealed.

In addition, a 0.5 mm thick A°C was constructed of only the core material 3 without cladding the brazing material and was annealed in the same manner as above.
-3i type board material was prepared separately.

The above-mentioned structural board material was cut into a size of 50 x 30 mm, and the Al-31 board material was cut into a size of 40 x 20 mm, and then each board material was degreased with a solvent and dried.

Then, the Al2-3i type plate material is
As shown in Figure 2, it was stood perpendicularly on the upper surface of a high-strength A12 alloy plate with the long side serving as the mounting surface. In addition, when using a plate material with only a core material, as shown in Fig. 2 (C), a brazing wire 5 with a diameter of 0.8 mm made of JIS 4104 alloy or 4343 alloy is placed at the joint part and the brazing material is supplied. It was decided that

Three methods were adopted for brazing properties, one of which was vacuum brazing, which was performed under a vacuum of 10-5 Torr, and J I S4104 alloy was used as the brazing material for the plating sheet or brazing material. . In the second method, a fluoride flux is applied to the joint and brazed in an N2 gas atmosphere, and the brazing material is JIS43
43 alloy was used. Furthermore, in the third method, brazing was performed in the atmosphere using a chloride flux, and a JIS 4343 alloy was used as the brazing material. In both brazing methods, the brazing temperature was 600° C. and the brazing time was 5 minutes.

After brazing, the cross section of the joint was observed as shown in FIG. 3, and the spread width W of the solder 6, the high strength, and the penetration depth H of the solder 6 into the alloy alloy were measured. Furthermore, the joint strength of the joined structures was measured by a tensile test, and
A tensile test was conducted only on high-strength Al alloy 1 after brazing. These results are shown in Table 1.

The results showed that in the examples of the present invention, the spread of the wax was appropriate, the penetration of the wax was shallow, and an appropriate fillet was formed. Therefore, the brazed condition was good, the fracture strength of the joint was high, and the fracture did not occur from the joint, but occurred in the other plate material, which had lower strength. Moreover, the material strength of the high-strength Al alloy material is also sufficiently high.

On the other hand, in the comparative example which did not have a coating layer, the spread of the solder was large and the penetration of the solder was deep, resulting in insufficient fillet formation. Therefore, the bonding condition was extremely poor, the breaking strength of the structure was low, and the breakage occurred at the bonded portion. Furthermore, the strength of the high-strength 11 alloy material was also extremely low.

[Example 2] In Example 2, one plate material was a plating sheet with a core material of high-strength Al alloy, and the other plate material was a plating sheet made of high-strength Al alloy.
The structural plate material was made of alloy or JIS300312 alloy.

As shown in Table 2, high strength Al alloy (No.

5-7), Brazing material for plating sheet (No.

a=c), covered l′! Pure Aff material for (cladding), JIS
3003 alloy was prepared respectively.

Each material was subjected to homogenization heat treatment and then thinly shaved.

After that, when high-strength Al alloy 10 is used for the structural pawl β-alloy plate material, one side of the high-strength Al alloy is coated with a thickness of 10% by hot rolling, as shown in Figure 4 (A). Linear β
A coating layer 11 consisting of the following was clad. In addition, structural AJ
When a JIS 3003 Al alloy was used for the 2 alloy plate material (not shown), it was thinned and then hot rolled without providing a coating layer. After the above-mentioned hot rolling, each of the structural A12 alloy plates was further cold rolled into a plate having a thickness of 1.5 mm.

In addition, as for the plating sheet, after the thinning, hot rolling produces a high-strength A
Both sides of the l-alloy 10 are clad with a coating layer 11 made of pure Al and a brazing material 12 with a thickness of 10% each, and further,
A plate material with a thickness of 1.5 mm was obtained by cold rolling.

For comparison, high-strength Al alloy plates without a pure Al coating layer were prepared as plating sheets and structural plates.

The plating sheet was cut into a size of 40 x 20 mm, and the structural plate material was cut into a size of 50 x 30 mm, and then degreased with a solvent and dried.

Next, in the same manner as in Example 1, the plating sheet was vertically erected on the structural board material, and brazing was performed.

The brazing conditions were the same as in Example 1: vacuum brazing, flux brazing in an N2 gas atmosphere, and flux brazing in the air, and the brazing temperature and time were also 600°C.
, for 5 minutes. In addition, in vacuum brazing, when alloy No. 5 or No. 6 is used as the core material of the plating sheet, the degree of vacuum is 2 X l 0-5 Torr, and when alloy No. 7 is used, is the degree of vacuum lX
It was set to 10-8 Torr.

Observe the formation status of Tween 1~ in the solder joint, observe the cross section of the solder joint and its vicinity, and examine the penetration depth of the solder into the plating sheet Z material and the structural Al alloy. Ta. In addition, the bonding strength of the brazing material structure was measured by a tensile test. These results are shown in Table 3.

As is clear from Table 3, when high-strength Al alloys were used for plating sheets or structural materials, those clad with pure Al provided a good brazed state and had excellent breaking strength.

However, in high-strength hole β alloys that were not clad with pure Al, the intrusion of solder was significant, the fillet formation was insufficient, the breaking strength was low, and the brazing properties were poor.

〔Effect of the invention〕

As explained above, according to the high-strength A°C gold alloy brazing method of the present invention, the Cu content is less than 2.0% by weight, the Si content is less than 1.2% by weight, and the Mg content is 0%. .3-5
．． Prior to brazing the high-strength Al alloy containing 6% by weight, pure A is added to at least the brazing surface of the high-strength Al alloy
A coating layer made of an Al2 alloy with a L or Mg content of less than 0.5% by weight is provided with a thickness of 1100 tL or more, and the high-strength Al alloy is brazed by melting the brazing filler metal. In this case, the fillet is appropriately formed and a good brazed state is obtained, and the use of the high-strength Al2 alloy has the effect that a high-strength brazing material structure can be obtained.

Further, according to the high-strength Al alloy material for brazed structures of the present invention, the Cu content is less than 2.0% by weight, and the S1 content is 1.0% by weight.
At least on the brazing surface of a high-strength Al alloy for brazing structures containing 0.3 to 5.6 wt% Mg, pure A°C or 8% Mg content less than 0.5 wt%. Since the four alloys are provided with a thickness of 100 μm or more, the above method can be carried out using a high-strength Al alloy material, and a high-strength brazing material structure with excellent brazing properties can be obtained. There is an effect.

Moreover, according to the plating sheet of the present invention, the Cu content is less than 2.0% by weight, the Si content is less than 1.2% by weight, and the plating sheet contains 0.3 to 5.6% by weight of Mg. AI
;! , an alloy is used as a core material, and at least on the brazed surface of this core material, a coating layer made of pure Al or 84 alloy with a Mg content of less than 0.5% by weight is provided with a thickness of 1100LL or more. Since the surface of this coating layer is coated with a brazing material, the above method can be carried out using a plating sheet having a high-strength core material, and the brazing sheet has good brazing properties and high strength. This has the effect of providing a ging sheet.

[Brief explanation of drawings]

FIG. 1(A) is a sectional view of a structural Al alloy material used in an embodiment of the present invention, FIG. 1(B) is a sectional view of a plating sheet, and FIG. 2(A) is a sectional view of a structural Al alloy material used in an embodiment of the present invention. Similarly, FIG. 2 (B) is a perspective view showing the state in which the plates are assembled together, FIG. 2 (B) is a front cross-sectional view when a plating sheet is also used, and FIG. The sectional view, Fig. 3, is the same sectional view of some parts, Fig. 4 (A).
4(B) is a cross-sectional view of a structural A12 alloy material used in another example, and FIG. 4(B) is a cross-sectional view of a plating sheet. l... High strength Au alloy 3... 2 material 5... Brazing wire rod 10... High strength Al alloy 12... Brazing metal 2... Covering layer 4... Brazing metal 6... Wax 11...Covering layer

Claims (1)

[Claims] 1. Cu content is less than 2.0% by weight, Si content is 1.
Prior to brazing a high-strength Al alloy containing less than 2% by weight and 0.3-5.6% by weight of Mg, the high-strength Al
A coating layer made of pure Al or an Al alloy with an Mg content of less than 0.5% by weight is applied to at least the brazing surface of the alloy.
Method 2 for brazing high-strength Al alloy, characterized in that the high-strength Al alloy is brazed with a thickness of 00 μm or more and the brazing filler metal is melted, and the Cu content is less than 2.0% by weight. , Si content is 1.
Pure Al or an Al alloy with an Mg content of less than 0.5% by weight, at least on the brazing surface of a high-strength Al alloy for brazing structures containing 0.3 to 5.6% by weight of Mg and less than 2% by weight A high-strength Al alloy material 3 for brazing structures, characterized in that a coating layer consisting of is provided with a thickness of 100 μm or more, a Cu content of less than 2.0% by weight, and a Si content of 1.0% by weight.
A high-strength Al alloy containing 0.3 to 5.6% by weight of Mg and less than 2% by weight is used as a core material, and at least the brazing surface of this core material has a pure Al or Mg content of 0.5% by weight. A high-strength Al alloy plating sheet, characterized in that a coating layer made of an Al alloy with a thickness of 100 μm or more is provided, and the surface of the coating layer is coated with a brazing material.