JPH02299772A - Method for joining cemented carbide and steel and the joined body - Google Patents

Abstract

PURPOSE:To obtain the securely joined body having a defectless joint boundary and high joint strength by using an insert material consisting of a specific material at the time of joining a cemented carbide and steel via a stress relieving material. CONSTITUTION:Joining of the cemented carbide 1 and the steel 5 is executed by using nickel or nickel-based alloy as the stress relieving material 3 and inserting an Ni-based brazing filler metal 2 between the cemented carbide 1 and the stress relieving material 3. In addition, an Ag-Cu-Pd brazing filler metal 4 is inserted between the steel 5 and the stress relieving material 3 and the insert materials 2, 4 in this laminated structural body are melted by heating. The defectless joint boundary is obtd. in this way and the joined body having the joint strength is obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method of joining cemented carbide and steel, and a joined body thereof.

(Prior art) Cemented carbide has traditionally been widely used as cutting tips, drawing dies, wear-resistant and impact-resistant tool parts such as crushers, and is often used as joint parts joined with steel. It is being said.

Various methods are known for joining such cemented carbide and steel, including mechanical methods such as bolt tightening and brazing methods using silver solder or copper solder.

However, when joining cemented carbide and steel by heating, as in the latter brazing method, since the difference in coefficient of thermal expansion between cemented carbide and steel is large, thermal stress caused by the difference in thermal expansion It is difficult to obtain healthy zygotes.

Therefore, in order to alleviate such thermal stress, a method is known in which a material with a coefficient of thermal expansion between cemented carbide and steel, or a ductile material such as copper or nickel, is used as a stress relieving material. It is being

When these joined bodies are used as a hammer for a crusher, flux brazing is performed using copper as a stress relaxation material and inserting silver solder.

In addition, in "Proceedings of the Welding Society" Vol. 6 (1988) No. f54, p. 499-504, copper is used as a stress relaxation material,
A method of inserting copper solder and brazing has been reported, and furthermore, in "Proceedings of the Welding Society" Vol. 3 (1985) No. 1 P, 105-109, a method using a nickel-based alloy as a stress relaxation material, A method of in-phase diffusion bonding has been reported.

(Problem to be Solved by the Invention) However, in the method of relieving thermal stress caused by a difference in thermal expansion using stress relieving materials as described above, it is difficult to use stress relieving materials such as cemented carbide and stress relieving materials, or steel and stress relieving materials. The joints must be sound. Further, when a bonded body is obtained using a stress relieving material, the strength thereof depends on the stress relieving material. Therefore, if higher strength is desired, nickel and nickel alloys, which are commonly used in the past, are preferable.

From this point of view, among the above bonding methods, the bonding method using copper as a stress relief material has a problem in terms of strength, and the bonding method using nickel-based alloy as a stress relief material by solid phase expansion. How?

There is a problem in that the high bonding temperature causes large thermal stress, making it impossible to obtain a sound bonded body.

The present invention solves the above-mentioned drawbacks of the prior art, and provides a joining technology that can provide a healthy joint interface and a joined body with high joint strength when joining cemented carbide and steel via a stress relaxation material. The purpose is to provide the following.

(Means for Solving the Problems) First, when using nickel or a nickel-based alloy as a stress relaxation material, the inventors have discovered that a material can be inserted into the insert 1 between the cemented carbide and the stress relaxation material, and between the steel and the stress relaxation material. We tried a method of joining using.

In this experiment, we first bonded using various insert materials shown in the comparative examples in Table 1, which are conventional techniques.When the insert material was a nickel-based filler metal, the bonding interface was sound, but when the insert material was a nickel-based brazing material, the bonding interface was sound, but it Similarly, due to the high bonding temperature, cracks occurred in the cemented carbide due to thermal stress. On the other hand, when the insert material is silver solder, the diffusion of the filler metal components into the stress relaxation material nickel and nickel alloy is large, making it impossible to obtain a sound bonding interface2. It has been found that it is very difficult to obtain a sound joint when using alloys.

Therefore, as a result of further research using various materials for the insert 1, the present invention has been achieved.

In other words, the method for joining cemented carbide and steel according to the present invention is a method of heat joining cemented carbide and steel via a stress relaxation material, in which nickel or a nickel-based alloy is used as the stress relaxation material, and the cemented carbide is and a Ni-based brazing filler metal between the steel and the stress relief material, and a Ni-based filler metal between the steel and the stress relief material.
-Cu I'd brazing material is inserted and the insert material in this laminated structure material is heated and melted.

In addition, in the cemented carbide and steel bonded body according to the present invention, nickel or a nickel-based alloy is interposed between the cemented carbide and the steel as a stress relaxation material, and the cemented carbide and the stress relaxation material are interposed between the cemented carbide and the steel. It is characterized by a layered structure in which a Ni-based brazing material is inserted between the steel and the stress relaxation material, and an Ag Cu-Pd brazing material is inserted between the steel and the stress relaxation material.

(Function) As mentioned above, the reason why nickel or a nickel-based alloy is used as a stress relaxation material in the present invention is to alleviate thermal stress caused by the difference in thermal expansion between cemented carbide and steel, and to increase bonding strength. . Note that the composition of the nickel-based alloy is not particularly limited, and permalloy or the like can be used.

As for the insert material, let's assume that the brazing filler metal has the same composition as before, that is, the insert between the cemented carbide and the stress relief material, and the insert between the steel and the stress relief material as the brazing filler metal of the same composition. In view of the fact that a sound bonded body cannot be obtained, the present invention is characterized in that a brazing filler metal with a different specific component system is used.

That is, by using a nickel-based brazing material between the cemented carbide and the stress relaxation material, the joint interface is made sound, and by using an Ag-Cu-Pd brazing material between the steel and the stress relaxation material, It is possible to obtain a bonding interface in which diffusion of the brazing filler metal into nickel and nickel alloy, which are stress relaxation materials, is suppressed. In addition, although nickel Jk brazing metal has a high joining temperature,
Since the solidus line of the Ag-Cu-Pd brazing material is lower than that of the nickel-based brazing material, the temperature at which thermal stress starts to occur is lowered, and thermal stress can be reduced.

Note that the component system and composition of the nickel-based brazing material as the insert material and the composition of the Δg-Cu-Pd brazing material are not particularly limited. Examples of nickel-based brazing filler metals include Ni-3L-B system, Ni-Cr-Si-Fe
-1'3 series and the like.

By heating and melting each insert material in the above laminated structure, a joined body of cemented carbide and steel is obtained. For this purpose, it is usually necessary to heat these laminated structures to a desired temperature. Of course, other heating modes are also possible, and the heating conditions can be adjusted as appropriate.

Preferably, the cemented carbide and the stress relaxation material are first joined with a nickel-based brazing material, and then the cemented carbide/stress relaxation material bonded body and the steel are joined using an Ag-Cu-Pd brazing material. A stronger bond can be obtained by using

The cemented carbide that is one of the materials to be joined can be a variety of materials, such as a composite material of WC carbide and Go, and the other steel can be carbon steel, alloy steel, tool steel, etc. It goes without saying that a variety of options are possible.

(Example) Next, examples of the present invention will be shown.

Lost bunches, as a material to be joined, 40! Cemented carbide (G2) with dimensions 111 x 40 m and steel (S
K D 11) was prepared, and Permalloy (76Ni-14Fe-4Mo-6Cu) was prepared as a stress relaxation material.

As shown in Experiment N11ll 3 (example of the present invention) in Table 1, first, 8
2Ni-7Cr-5Si-3Fe-3B brazing filler metal was inserted and heated in a furnace at 1050°C for 10 minutes to join.

Next, a 59Ag-31Cu-10Pd brazing filler metal was inserted between the obtained joined body and a steel having dimensions of 40 mm x 40 mm, and heated in a furnace at 850° C. for 10 minutes to obtain a joined body of cemented carbide and steel.

When an ultrasonic flaw detection test was performed on the bonded body, no defect echo was detected at the interface, and the bonding rate (area where no flaw echo was observed in the ultrasonic flaw detection test/total area) was 111.
00% zygote. Also, the shear strength of the joined body is 25
kgf/v++2.

As in Example 1, the material to be joined was 405m x 40ra.
Cemented carbide (G2) with l1 dimensions and 40mm x 40mm
Prepare dimensional steel (SKDII) and use permalloy (76Ni-14Fe-4Mo-6Cu) as stress relaxation material.
prepared.

As shown in experiment Nα14 (example of the present invention) in Table 1, first, 92 N was applied between the cemented carbide and the stress relaxation material.
Insert i-7St-2B brazing filler metal.

Bonding was performed by heating at 1050° C. for 10 minutes in a furnace.

Next, a 59Ag-31Cu-10Pd brazing filler metal was inserted between the obtained joined body and the steel with dimensions of 40mm x 40++*, and heated in a furnace at 850'C for 10 minutes to form a joined body of cemented carbide and steel. I got it.

When the bonded body was subjected to an ultrasonic flaw detection test, it was found that the bonding rate was 95%. Also, the shear strength of the joined body is 25
kgf/am”.

Similar to Example 1, the material to be joined is 40+vX40mm.
Cemented carbide (G2) with dimensions and steel (SKDII) with dimensions of 40 mm x 40 mm were used, and permalloy (76Ni-14Fe-4Mo-6Cu) was prepared as a stress relaxation material.

As shown in Experiment & 15 (example of the present invention) in Table 1, 82Ni-7Cr was added between the cemented carbide and the stress relaxation material.
-5SL -3Fe -3B brazing filler metal and 5Q Ag -31Cu -10Pd brazing filler metal were inserted between the stress relaxation material and the steel as shown in Fig. 1, and heated at 1050℃ in a furnace. They were heated for 10 minutes and bonded.

When the bonded body was subjected to an ultrasonic flaw detection test, no defect echo was detected at the interface, and the bonding rate was 100%. Also, the shear strength of the joint is 15kgf/11m”
Met.

As in Example 1, the material to be welded is 50mm
II11 dimension cemented carbide (G2) and 50mm x 50o
Prepare steel (545C) with +m dimension fm, and add 4! of Ni as stress relaxation material! Prepared.

As shown in the experiment Na 1 G (example of the present invention) in Table 1, first, 82
A Ni-7Cr-5SL-3Fe-3B brazing filler metal was inserted and bonded by heating at 1050° C. for 30 minutes in a furnace.

Next, the obtained bonded body and 50mm x 50III+o
A 68Ag-27Cu-5Pd brazing filler metal was inserted between two pieces of steel, and heated in a furnace at 850°C for 15 minutes to obtain a joined body of cemented carbide and steel.

An ultrasonic flaw detection test was conducted on the joined body.

The bonded body had a bonding rate of 96%. The shear strength of the bonded body was 23 kgf/1IIff12.

Ω-Example j Same as Example 1, the material to be joined is 40m+X40m
Cemented carbide (G7) with m dimensions and steel (SKDLL) with dimensions of 40 mm x 40 mm were prepared, and NiJ was used as a stress relaxation material.
, G alloy (79Ni-17Fe-4Mo) was prepared.

As shown in Experiment NQ 1-7 (example of the present invention) in Table 1, first, 82
A NL-7Cr-5Si-3Fc-3I3 brazing filler metal was inserted and bonded by heating at 1050° C. for 10 minutes in a furnace.

Next, the obtained zygote and 40mo+X 40+nn+
A 65Ag-20Cu 15Pd brazing filler metal was placed between the sized steel inserts and heated in a furnace at 900°C for 5 minutes.

A cemented carbide and steel joint was obtained.

When the bonded body was subjected to an ultrasonic flaw detection test, the bonding rate was 1.
00% zygote. Also, the shear strength of the joined body is 22
kgf/mm”.

Resonance ■1L First, as in Example 1, as the material to be joined, 40mm x 4
0mm dimension cemented carbide (G2) and 40+amX401
Prepare steel (SKDII) with dimensions Im, and use permalloy (76Ni-14Fe-4Mo-6) as a stress relaxation material.
Cu) 1! ! Biased.

Then, as shown in FIG. 1, various insert materials shown in Examples 9 No. 1 to No. 9 (Comparative Examples) in Table 1 were heated and bonded in a furnace.

As shown in Table 1, the results showed that cracks occurred in the cemented carbide and peeling occurred at the interface. Furthermore, even when a bonded body was obtained, defects were found on almost the entire bonded surface when an ultrasonic flaw detection test was performed.

First, as in Example 1, as the material to be joined, 40 mm x 4
0mm dimension cemented carbide (G2) and 40mmX40II
I'CI! steel (SKDII) with l11 dimensions! Permalloy (76Ni -1' 4 Fe
-4Mo-6Cu) was prepared.

As shown in Experiments Nα10 to Nα12 (comparative examples) in Table 1, first, a nickel-based brazing material was inserted between the cemented carbide and the stress relaxation material, and they were heated and bonded in a furnace.

Next, Ag-Cu brazing material or AE-Cu-"I"i brazing material is inserted between the obtained joined body and the steel, and heated in a furnace to obtain a joined body of cemented carbide and steel. Ta.

When the bonded bodies were subjected to a deep scratch test using ultra-low-frequency waves, it was not possible to obtain bonded bodies with a bonding rate of 90% or higher. Further, when the Ag-Cu-Ti brazing material was inserted (Nci 10''Nn 11), the shear strength of the joint was only 5 kgf/mm''.

[Blank 1 (Effects of the Invention) As detailed above, according to the present invention, when joining cemented carbide and steel via a stress relaxation material, nickel or a nickel-based alloy is used as the stress relaxation material. However, since the insert material is made of a specific material, the bonding interface is sound.
A strong bonded body with high bonding strength can be obtained.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram showing the configuration of a laminated structure. DESCRIPTION OF SYMBOLS 1...Cemented carbide, 2...Cemented carbide/stress relaxation material side insert, 3...Stress relaxation material, 4...Steel/stress relaxation material side insert, 5...Steel. Patent applicant: Kobe Steel, Ltd. Patent attorney Hisashi Nakamura Figure 1

Claims (2)

[Claims] (1) In a method of thermally joining cemented carbide and steel via a stress relaxation material, nickel or a nickel-based alloy is used as the stress relaxation material, and N between the cemented carbide and the stress relaxation material is used.
Cemented carbide and steel characterized by inserting an i-based brazing material, inserting an Ag-Cu-Pd brazing material between the steel and the stress relaxation material, and heating and melting the insert material in this laminated structure material. joining method. (2) Nickel or a nickel-based alloy is interposed as a stress relaxation material between the cemented carbide and the steel, and a Ni-based filler metal is inserted between the cemented carbide and the stress relaxation material, and the steel A joined body of cemented carbide and steel, characterized by having a laminated structure in which an Ag-Cu-Pd brazing filler metal is inserted between stress relaxation materials.