JPS63295095A - Brazing filler metal - Google Patents

Abstract

PURPOSE:To stably obtain a joint which is defectless and has high strength by forming a brazing filler metal of a compsn. contg. specific ratios of Sn, Ni and further B and consisting of the balance substantially Cu. CONSTITUTION:The brazing filler metal is formed of the compsn. contg., by weight %, 10-30% Sn, <=10% Ni, and further <= 2% B, and consists of the balance substantially Cu. Since there is the addition of B, the infiltration of the solder into the iron grain boundary is effectively prevented; in addition, the space packability is improved. The joint which is defectless and has the high strength is thus obtd.

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention relates to the improvement of a Cu-3n alloy brazing filler metal, and more specifically, to the improvement of a Cu-3n alloy brazing filler metal. Cu- which made it possible to obtain a sound joint.
This relates to a 5n-based brazing filler metal.

[Conventional technology]

There are various types of brazing filler metals in the past, but the targets are iron-iron (iron means iron-based material, the same applies hereinafter), copper (means copper-based material, the same applies below)-iron vacuum or atmosphere. When it comes to hard brazing materials for furnace brazing, there are three types: copper brazing, silver brazing, and copper-tin alloy brazing.

Copper solder is used for iron-iron, but it can only be applied to that metal and has a high melting point, resulting in high running costs.

Silver solder is effective for both iron-iron and copper-iron combinations, but it is expensive because it contains a large amount of silver.

On the other hand, copper-tin alloy solder can be applied to both iron-iron and copper-iron, and has the advantage of being significantly lower in cost than silver solder. Therefore, it can be said to be particularly useful for simultaneous furnace brazing of iron-iron and copper-iron, and for furnace brazing of copper-iron.

Specifically, the copper-tin alloy solder is Sn10-3
Those containing 0% (by weight, hereinafter the same) and 10% or less of Ni are known.

(Problems to be Solved by the Invention) However, this copper-soot based alloy brazing material has the following problems.

First, during the brazing process, wax invades the grain boundaries of iron. If the solder penetrates into the grain boundaries, the internal residual stress of the solder material itself or the stress applied from the outside will cause
This causes so-called liquid metal embrittlement, which is a problem.

Second, although the lateral strength of a brazing filler metal is generally the most important point, copper-tin alloy brazes of known compositions have difficulty in gap-filling properties.

-i In copper-tin alloys, for example, as described in 1 Japan Institute of Metals Proceedings 1984 Spring Conference (p615) J, as the tin content increases, the gap filling property decreases significantly. . One purpose of adding Ni is to improve the gap-filling property, but adding Ni alone is insufficient and cannot ensure high-level properties.

The present invention solves the above problems, prevents the penetration of solder into grain boundaries, and exhibits excellent performance in terms of gap-filling properties.
The purpose of the present invention is to provide a copper-tin alloy brazing material that does not have any problems in lateral strength.

[Means for solving problems]

The present inventors conducted detailed experiments to determine the effects of various additive elements on the properties of the brazing filler metal in copper-soot alloy brazing filler metals.
As a result of our investigation, we found that B is extremely effective in both preventing the penetration of solder into the grain boundaries and improving the gap-filling properties.Additionally, B can completely prevent liquid metal embrittlement caused by penetration of the solder into the grain boundaries, and can also fill the gaps. It was discovered that the properties of this material could be raised to a level sufficient to be used as a brazing material.

The present invention was made based on this knowledge, and Sn10
~30%, N1IO or less, and further contains 82% or less, with the remainder consisting essentially of Cu.
The main topic is tin-based alloy brazing filler metals.

FIG. 1 shows the results of an experiment showing the effect of B on gap filling properties in a copper-tin alloy brazing filler metal.

The experiment was based on Cu-20%5n-3%Ni and varied the amount of B added to 0%, 0.2%, and 0.4% to determine the relationship between clearance and penetration height. The following method was used. That is, l5O5179-1983(E)
Using the cylindrical pipe brazing flow test method in accordance with
The clearance created between the cylinders and the height at which the wax flows were measured.

According to the figure, as the amount of B added increases, the penetration height at the same clearance increases, and the clearance at which the same /J1 penetration height is obtained increases. this is,
This shows that the addition of B is effective in improving the gap-filling properties, and as the amount of B is increased, the gap-filling properties become higher.

Next, the influence of B on solder transverse strength (shear strength) is as follows.

Figure 2 shows the relationship between the amount of B added and shear strength.

This is the result of examining shear strength by varying the amount of B added under the conditions of Cu-20%5n-3%Ni. 111
In this study, we conducted furnace brazing at 970°C under the same iron-iron conditions as in the case of Fig. 1 using such various brazing filler metals, and performed a method according to JIS G0601 on the obtained products. (Using a capacity 2QT'on Amsler type universal test material) The shear strength of the brazed portion was examined.

According to this, there is a tendency for the Bl to be minimal in the region of O, l-0, 2%, but overall the shear strength value is within a level that poses no problem for practical use.

However, when the amount of B exceeds 2%, it breaks this practical range. This is the reason why the upper limit of the B content is set to 2% in the present invention.

In addition, in the present invention, no lower limit was defined for the B content. This is because even a very small amount of B can be expected to have a corresponding effect, but especially from the perspective of preventing penetration of solder grain boundaries, it is preferable to keep it at 0.4% or more.Within this range, penetration of solder grain boundaries is completely prevented. This is because it can be resolved.

Next, the reason for limiting the content of Sn and Ni, which are components other than B, will be described.

Sn: Sn is an additive component for lowering the melting point, but if it is less than 10%, its effect is not sufficient and the melting point becomes high, specifically about 100'0°C or higher.

If the melting point of the brazing filler metal is as high as this, the Cu concretions in the copper member will become coarse in copper-iron brazing, and such a concretion is practically impermeable.

Moreover, when the amount of Sn exceeds 30%, the brazing strength (shear strength) shows a sudden decrease, and a practical level of strength cannot be obtained.

This trend is clear in Figure 3. The figure shows Cu-5%N
The shear strength was observed by changing the Sn content under the conditions of i (the brazing conditions and shear test were the same as in Figure 2 above), and as a whole, as the amount of 3n was increased or decreased, Although there is a tendency for the shear strength to decrease, 5n3
In the range of 0% or less, the decrease is gradual, and the shear strength remains at a level that poses no problem for practical use. However, 5n
In the range of 30%, the shear strength rapidly decreases and falls below the practical level.

For the above reasons, Sn was set in the range of 10 to 30%.

Ni: Ni is an effective component for improving shear strength and gap filling properties.

Figure 4 shows the effect of Ni on shear strength, and this shows the shear strength by changing the N1-containing star under Cu-20%Sn conditions (brazing and test methods are the same as in Figure 3). It is.

As is clear from the figure, the shear strength shows a long-term value when the Ni content is 3 to 5%, and the improving effect of Ni is lost when it exceeds 10%.

Therefore, Ni was limited to 10% or less.

Note that Ni in this range of content also effectively acts on the gap-filling property.

The lower limit of Ni is not particularly specified because even a very small amount does not pose any particular problem.

〔Example〕

The presence or absence (or degree) of grain boundary penetration of the solder, gap filling properties, and shear strength of the copper-tin alloy brazing fillers having the various compositions shown in Table 1 were investigated using the methods described above. Gap filling property and shear strength were investigated for both iron-iron and copper-iron cases.

The results were as shown in the right column of Table 1.

Table 1 Note 1: ○: No penetration of filler grain boundaries △: Same <fi9,
×Also remarkable Note 2: The present invention examples containing B, which shows the penetration height at a clearance of 0.3, have good results in all respects of filler grain boundary penetration, gap filling property, and shear strength. In the example 11 of the present invention shown in 0, 11 contains B and has a GTMt of 0.
．． Since it was less than 4%, there was a tendency for grain boundary penetration, but this was also extremely slight.

On the other hand, in the comparative example, at least one of the above three characteristics is not sufficient. That is, as in 8, Bjld
If it is set to 0%, penetration of solder grain boundaries will occur and gap-filling properties will also deteriorate. When the Ni amount is reduced to 0% as in Case 9, the gap filling property and shear strength decrease. On the other hand, when the Ni content is increased to 15% as in floor 10, the shear strength decreases compared to the case without Ni addition, and the addition becomes meaningless. When the Sn content is kept as low as 7%, as in NQll, the shear strength increases, but the gap filling property decreases and the copper crystal grains become coarser, making it unsuitable for practical use.

〔Effect of the invention〕

As is clear from the above explanation, the brazing filler metal of the present invention is
Although it is a tin-based alloy brazing filler metal, the addition of B makes it extremely effective in preventing solder from penetrating into iron grain boundaries, and its gap-filling properties are significantly better than that of conventional copper-tin alloy brazing filler metals. It is excellent and also satisfies the practical level in terms of brazing strength. Therefore, if the brazing filler metal of the present invention is used, iron-iron, copper-
In any combination of irons, it is possible to stably obtain a sound and high-strength joint. In addition, conventional copper
Even in cases where manual flame brazing was required to ensure strength, such as furnace brazing of iron, automatic diagram furnace brazing can be applied by providing high-strength joints. becomes.

Therefore, the present invention will greatly contribute to improving the quality of brazed products and reducing brazing costs.

[Brief explanation of the drawing]

Figure 1 is a plot of experimental results showing the effect of B on gap filling properties, Figure 2 is a plot of experimental results showing the relationship between the amount of B added and shear strength, and Figure 3 is the effect of Sn on shear strength. Figure 4 is a plot diagram of the experimental results showing the N
FIG. 3 is a plot of experimental results showing the influence of i on shear strength. cS, @affected r-i Figure 3 Figure 4

Claims (1)

[Claims] (1) A brazing filler metal characterized in that it contains 10 to 30% Sn, 10% or less Ni, and 2% or less B, with the balance being substantially Cu.