JPS62259696A - Cu alloy brazing filler metal for brazing of sintered head alloy and steel member - Google Patents

Abstract

PURPOSE:To prevent the chipping and dislodgment of a tip and to improve the service life thereof by executing brazing by using a Cu alloy made of a compsn. contg. specific ratios of Zn, Mn, and Co and consisting of the balance Cu and unavoidable impurities. CONSTITUTION:A sintered hard alloy member and steel member are brazed by using the Cu alloy contg. 35-45% Zn, 1.5-3% Mn, and 1.5-3% Co. The brazing is executed at 0.25-0.5mm brazing allowance and <=975 deg.C brazing temp. The brazed members are preferably cooled at >=5 deg.C/sec cooling rate until the brazing filler metal solidifies after the completion of brazing. The uniform structure is thereby formed and as a result, the brazing layer which has low high-temp. deformation resistance, small residual stress after the brazing, and high ordinary-temp. strength is obtd.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a combination of a WCC cemented carbide member (hereinafter referred to as a cemented carbide member) containing tungsten carbide (hereinafter referred to as WC) as a main component and a steel member. The present invention relates to a Cu alloy brazing material suitable for use in brazing.

[Conventional technology]

BACKGROUND ART Generally, in the manufacture of drilling bits, cutters, cutting tools, etc., a cemented carbide member, such as a cemented carbide tip, is brazed to a steel member, such as a steel alloy.

For brazing these two parts, Ag solder, Cu
It is also well known that Cu alloy brazing materials such as -Mn alloy and Cu-Zn alloy are used.

[Problem that the invention seeks to solve]

However, the above-mentioned Ag brazing filler metal has the problems of low brazing strength and easy peeling, and is also expensive; furthermore, although the above-mentioned conventional Cu alloy brazing filler metal can achieve high brazing strength, Since both of these structures are α single-phase structures, their coefficient of linear expansion is larger than that of cemented carbide members, and their high-temperature deformation resistance during brazing is also large, resulting in a large There is a problem in that deformation strain remains and as a result, cracks are likely to occur in the cemented carbide member.

[Means for solving problems]

Therefore, the present inventors conducted research to develop a brazing filler metal that does not have the problems of conventional brazing fillers as described above.
The brazing filler metal contains, in weight% (hereinafter "wt%"), Zn: 35 to 45%, Mn: 1.5 to 3%, Co: 1.5 to 3%, and the remainder is Cu. When composed of a Cu alloy having a composition consisting of and inevitable impurities, the Cu alloy with and has an α phase and a β phase.
This β
Due to the presence of the phase, the coefficient of linear expansion is large, but the high-temperature deformation resistance during brazing is extremely low.As a result, the residual strain after brazing is extremely small, which may cause cracks to occur in cemented carbide members. The absence of shea, and the presence of the β phase improves the room temperature strength of the brazing filler metal, resulting in a marked increase in the fatigue strength of the brazing layer.
They found that it has even higher brazing strength and is less expensive.

This invention has been made based on the above knowledge, and the reason why the component composition of the brazing filler metal is limited to the above-mentioned standard will be explained below.

(a) Zn The Zn component has a β phase that lowers the yield stress of the brazing filler metal during brazing, that is, the high-temperature deformation resistance, thereby reducing the deformation strain after brazing and improving the room-temperature strength of the brazing filler metal. However, if the content is less than 35%, it is not possible to substantially cause the β phase to appear, and therefore the above-mentioned effect cannot be ensured.On the other hand, if the content exceeds 45%, The content was set at 35 to 45% since strength and elongation tend to decrease.

(b) Mn The Mn component has the effect of improving wettability with parts and improving the room temperature strength of the brazing filler metal.
．． If the content is less than 5%, the desired effect cannot be obtained; on the other hand, if the content exceeds 3, although the high temperature strength of the brazing material increases, Mn oxidation phenomenon occurs during brazing. Since brazing defects are likely to occur, its content is set at 1.5 to 3%.

(c)　C.

The CO acid component prevents elution of the CO acid component contained in the cemented carbide component as a binder phase forming component during brazing,
This has the effect of suppressing the formation of a Co-free layer on the brazing surface of the cemented carbide member, thereby preventing a decrease in the strength of the cemented carbide member, but if the content is less than 1.5%, the The desired effect cannot be obtained in the action, and on the other hand, even if the content exceeds 3 g, the effect of further improvement due to the action will not appear, and on the contrary, it will become difficult to manufacture the brazing filler metal, so the content should be reduced to 1. It was set at 5-3%.

When performing brazing using the CU gold alloy filling material of the present invention, the brazing temperature should be 975°C or lower, and after brazing is completed, the brazing temperature should be set at 5°C/Sec until the brazing material solidifies.
It is desirable to cool at a cooling rate higher than that, so that a structure in which the α phase and β phase are uniformly dispersed is formed.As a result, the high temperature deformation resistance is low, and the residual strain after brazing is small. , and a brazing layer with high strength at room temperature can be obtained.

Further, it is desirable that the brazing allowance is 0.25 to 0.5 mm, which can prevent the occurrence of cracks in the cemented carbide member.

〔Example〕

Next, the Cu alloy brazing filler metal of the present invention will be specifically explained using examples.

By preparing molten metals having the compositions shown in Table 1 using a normal melting method, casting them, rolling them under the same normal conditions, and wire-drawing them, the diameter of each metal is 1.
．． Cu alloy brazing filler metals 1 to 7 of the present invention having a diameter of 6 orchid φ, comparison C
U-alloy brazing filler metals 1 to 6 and conventional brazing filler metals 1 to 3 were manufactured, respectively.

In addition, comparative CU gold alloy fillers 1 to 6 all have compositions in which the content of one of the constituent components (those marked with * in Table 1) is outside the scope of this invention. It is.

Table 1 (*marked: outside the scope of the present invention) Next, using these various brazing materials, the tip diameter: 95
J on the tip surface of uφ low alloy steel base metal (steel member)
Four cemented carbide chips (cemented carbide members) having a composition corresponding to Step 5-p40 were brazed at a temperature of 950°C, a brazing distance of 0.3 m, and a cooling rate after brazing of 7°C/se.
A drilled Iwatsuki bit was manufactured by brazing it to a cross under the conditions of (by N2 gas spraying).

Then, using these drilling bits, the number of revolutions: 20
Drilling was carried out in andesite under conditions of 0r, pm, and impact crab 3 at a depth of 9 m, and the length of the hole until the end of its service life was measured.

These results are shown in Table 1 as an average value of 10 samples.

〔Effect of the invention〕

As shown in Table 1, Cu alloy brazing materials 1 to 7 of the present invention
All of the bits manufactured using brazing filler metals 1 to 3 had a long service life, and all of them reached the end of their service life due to normal wear. It is clear that the carbide tip also suffers from chipping and falling off, resulting in a relatively short service life.

Furthermore, as seen in the bits manufactured using comparative Cu alloy brazing fillers 1 to 6, even if the content of any of the components constituting the brazing filler metal falls outside the range of the present invention, the desired service life may not be achieved. It is clear that the cemented carbide tip has a short service life due to chipping and peeling.

As mentioned above, according to the Cu alloy brazing material of the present invention, it is possible to braze a steel member and a cemented carbide member at a low cost, and in practical use, it is possible to braze a steel member and a cemented carbide member without damage or peeling. Since this does not occur, industrially useful effects such as a long service life can be achieved.

Claims (1)

[Claims] Zn: 35 to 45%, Mn: 1.5 to 3%, Co: 1.5 to 3%, and the remainder is Cu and unavoidable impurities (wt%). A Cu alloy brazing filler metal for brazing a cemented carbide member whose main component is tungsten carbide and a steel member, characterized in that it is made of a Cu alloy having tungsten carbide as a main component.