JP2005036281A - Joining method for cemented carbide, and joined cemented carbide - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a joining method for cemented carbide capable of joining without using a die for joining and further having high productivity, and to provide cemented carbide joined thereby. <P>SOLUTION: The joining method for cemented carbide is provided with a joining process where cemented carbide members (alloy members) 3 and 5 consisting essentially of tungsten carbide (WC) are joined to the object 6 to be joined directly contacted at the mutual joining faces 3A and 5A in the upper and lower directions by performing pulse conducting while applying pressure between the cemented carbide members 3 and 5 from the upper and lower directions. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a cemented carbide alloy mainly composed of tungsten carbide and a cemented cemented carbide joined by this method.

A cemented carbide member mainly composed of tungsten carbide (WC) is excellent in mechanical strength and heat resistance, and is often used in fields where high strength and heat resistance are required. For this reason, when a cemented carbide member is used by being joined, there is a problem that sufficient strength cannot be obtained at the joint by ordinary brazing. Therefore, by sintering a cemented carbide member mainly composed of WC and a cemented carbide member or a steel member with a powder composed of WC and cobalt (Co) interposed therebetween, this powder is sintered. There has been proposed a method of bonding the two by acting as a bonding agent (see, for example, Patent Document 1).
Japanese Unexamined Patent Publication No. 7-3306

However, in the above conventional joining method, since the powder is sandwiched and sintered, the sintered members need to be inserted into a mold and sintered. For example, a groove is provided on the joining surface. Such a complicated shape cannot be put into a mold, so that there is a problem that it cannot be used for joining such members. Further, since it is necessary to prepare a mold, there is a problem that the process becomes complicated and the productivity is lowered.
The present invention has been made in view of the above circumstances, and is capable of joining without using a joining die, and is a highly productive cemented carbide joining method and a joined cemented carbide alloy joined thereby. The purpose is to provide.

The present invention employs the following means in order to solve the above problems.
The cemented carbide joining method of the present invention is a method of joining alloy members, at least one of which is a cemented carbide member, with the alloy members being brought into direct contact with each other at the joining surface to apply pressure between the alloy members. It is characterized by comprising a joining step in which pulse energization is performed while applying, and at least one of the alloy members is a cemented carbide member mainly composed of tungsten carbide (WC).

  Since this cemented carbide joining method includes the above-described steps, by applying a pulse current, a discharge is generated between the joining surfaces of the objects to be joined and locally becomes a high temperature state and melts microscopically. . Since pressure is applied at this time, plastic deformation occurs at the joint surface, and the gap disappears. Therefore, even a high melting point cemented carbide having tungsten carbide (WC) as a main component can be bonded with high strength.

The present invention is the joining method of the cemented carbide, wherein the pressure is preferably 1 MPa or more and 100 MPa or less.
In this cemented carbide joining method, pressurization is performed at the above pressure, so that a sufficient joining force can be obtained as compared with a case where the cemented carbide is less than 1 MPa. Moreover, it can join in the state which suppressed the deformation amount of alloy member itself compared with the case where it is larger than 100 Mpa.
The pressure at this time may be 1 MPa or more and 100 MPa or less, preferably 5 MPa or more and 100 MPa or less, and more preferably 10 MPa or more and 50 MPa or less.

The present invention is a bonding method of the cemented carbide, wherein the other alloy member preferably contains any one of tungsten, nickel, and chromium as a main component.
In this cemented carbide joining method, since the other alloy member has the above-described configuration, it can be plastically deformed at a temperature lower than that of the cemented carbide and can be joined at a temperature lower than those of the cemented carbides. can do.

The present invention is also a method for joining the cemented carbide, wherein the roughness of the joining surface is preferably 10 μm or less in terms of the surface roughness Ry expressed by the maximum height.
In this cemented carbide joining method, since the surface roughness Ry of the joint surface is 10 μm or less, the void generated when joining at the joint surface is suppressed as compared with the case of joining at the surface roughness Ry exceeding 10 μm. And can be joined with sufficient joining strength.

Moreover, this invention is the joining method of the said cemented carbide alloy, Comprising: It is preferable to heat the said alloy member to the temperature of 800 degreeC or more and 1600 degrees C or less at the time of the said joining process.
Since this cemented carbide joining method is heated to 800 ° C. or higher, a joining reaction can be generated when the article to be joined includes an alloy member having a melting point lower than that of the cemented carbide member. In addition, since the heating of the objects to be joined is set to 1600 ° C. or lower, it is possible to join the alloy members themselves while suppressing the plastic deformation and maintaining the shape before joining.
The bonding temperature may be 800 ° C. or higher and 1600 ° C. or lower, preferably 1000 ° C. or higher and 1400 ° C. or lower, more preferably 1200 ° C. or higher and 1400 ° C. or lower.

The present invention is also a method of joining the cemented carbide, wherein the heating is preferably performed by pulse energization.
In this cemented carbide joining method, heating is performed by pulse energization, so that a sufficient temperature can be supplied without providing a separate means for heating the alloy member.

  The cemented cemented carbide of the present invention is a cemented cemented carbide in which alloy members, at least one of which is a cemented carbide member, are joined, and according to any one of the cemented carbide joining methods according to the present invention. It is characterized by being joined.

  Since this bonded cemented carbide is bonded by the bonding method of any one cemented carbide of the present invention, even if the shape of each alloy member does not match or has an intricately shaped alloy member, Each shape is maintained and high bonding strength can be obtained.

The present invention described above has the following effects.
According to the cemented carbide joining method and cemented cemented carbide of the present invention, it is not necessary to insert a bonding agent such as powder between the alloy members. Even if it is alloy members, it can join in the state which maintained each other's shape. Moreover, since it is not necessary to use a mold | die at the time of joining, productivity can be improved.

An embodiment of the present invention will be described with reference to FIGS. 1 and 2.
The cemented carbide joining method according to the present embodiment is a method of joining alloy members, at least one of which is a cemented carbide member, using the discharge plasma sintering apparatus 1 shown in FIG. This is a method of manufacturing a cemented cemented carbide 2 as shown.
In this joining method, a cemented carbide member (alloy member) 3, 5 containing tungsten carbide (WC) as a main component is directly contacted with a workpiece 6 in which the joining surfaces 3 A, 5 A are in direct contact with each other in the vertical direction. To cemented carbide members 3 and 5, a joining process is carried out by applying a pulse current while applying pressure between them.

  The discharge plasma sintering apparatus 1 includes a vacuum chamber 8 in which a sintering unit 7 is disposed, and an upper punch electrode provided above and below the vacuum chamber 8 and sandwiching the sintering unit 7 therebetween. 10 and a lower punch electrode 11 and a power supply unit 12 for applying pulsed power to the sintering unit 7 through these electrodes.

The sintering unit 7 is connected to a pressurizing mechanism 13 (for example, a hydraulic press mechanism), and is connected to the pressurizing mechanism 13 and connected to the pressurizing mechanism 13. And a lower punch 16 for applying pressure from the lower end 6b.
The upper punch 15 is in contact with and electrically connected to the upper punch electrode 10 at the upper portion, and the lower punch 16 is in contact with and electrically connected to the lower punch electrode 11 at the lower portion.

Next, a method for manufacturing the cemented carbide according to the present embodiment having the above configuration will be described below.
First, the cemented surface 5A of the cemented carbide member 5 is formed on the cylindrical cemented carbide members 3 and 5 having WC as a main component and a finished surface having a surface roughness Ry of 10 μm or less of the bonded surfaces 3A and 5A. The surface which becomes the lower end 6b of the article 6 to be bonded is placed in contact with the lower punch 16 on the upper side. On top of this, the cemented carbide member 3 is placed so that the bonding surface 3A faces and contacts the bonding surface 5A.
The upper punch 15 of the sintering unit 7 is brought into contact with the upper end 6a of the workpiece 6 thus formed.

Next, the vacuum chamber 8 is depressurized by a vacuum pump (not shown) until a predetermined degree of vacuum is reached.
Then, the pressurizing mechanism 13 is driven to pressurize a predetermined compressive force of 1 MPa or more and 100 MPa or less from the vertical direction to the workpiece 6 through the upper punch 15 and the lower punch 16.
At the same time, a pulse voltage is applied between the upper punch electrode 10 and the lower punch electrode 11 at a predetermined frequency from the power supply unit 12 to perform pulse energization.

At this time, a discharge is generated in the gap formed between the bonding surface 3A and the bonding surface 5A, and the article 6 is heated to a temperature of 800 ° C. or higher and 1600 ° C. or lower. At this time, oxide films, impurities, dirt, and the like formed on the surfaces of the bonding surfaces 3A and 5A are evaporated and scattered, and the bonding surfaces 3A and 5A are microscopically melted. On the other hand, since the compressive force is applied, the strain energy is accumulated.
And the uneven | corrugated | grooved part on joining surface 3A, 5A plastically deforms according to the effect of a thermal energy and distortion energy, and a clearance gap is lose | eliminated, and joining surface 3A and joining surface 5A are joined.
When pressurization and pulse energization are stopped at a predetermined temperature, the cemented cemented carbide 2 is formed.

According to this cemented carbide joining method, even when joining a high melting point cemented carbide member mainly composed of tungsten carbide (WC), it is joined with high strength without using powder as a bonding agent. be able to.
At this time, since the pressure is 1 MPa or more, a sufficient bonding force can be obtained as compared with a case where the pressure is less than 1 MPa. In addition, since the pressure is 100 MPa or less, it is possible to perform bonding in a state where the deformation amount of the workpiece 6 itself is suppressed as compared with a case where the pressure is larger than 100 MPa.
In addition, since the surface roughness Ry of the bonding surfaces 3A and 5A is 10 μm or less, it is possible to suppress voids generated when bonding is performed on the bonding surfaces, and to improve the bonding strength more effectively.

Furthermore, the object to be bonded 6 can be heated by pulse energization without providing a separate heating means. At this time, since the object to be bonded 6 is heated to 800 ° C. or higher, the object to be bonded 6 is made of the cemented carbide members 3 and 5. In the case where an alloy member having a low melting point is provided, the bonding reaction can be generated more satisfactorily than in the case of a temperature lower than 800 ° C. Further, since the heating of the workpiece 6 is 1600 ° C. or less, the pre-joining shape is maintained while suppressing the plastic deformation of the high melting point cemented carbide members 3 and 5 themselves as compared with the temperature exceeding 1600 ° C. Can be joined.
Therefore, even if the shape of each alloy member does not match or a complex shape alloy member is provided, each shape can be maintained and bonding can be performed with high bonding strength.

The technical scope of the present invention is not limited to the above embodiment, and various modifications can be made without departing from the spirit of the present invention.
For example, in the above-described embodiment, the alloy member has a cylindrical shape, but the joining surface may have a groove processing, a hole, or a complicated shape.
Moreover, you may join not only when joining an alloy member from an up-down direction but from a horizontal direction.
Furthermore, the pressure may be 1 MPa or more and 100 MPa or less, preferably 5 MPa or more and 100 MPa or less, and more preferably 10 MPa or more and 50 MPa or less.
The bonding temperature may be 800 ° C. or higher and 1600 ° C. or lower, preferably 1000 ° C. or higher and 1400 ° C. or lower, more preferably 1200 ° C. or higher and 1400 ° C. or lower. At this time, the optimum temperature for joining is determined by the material of the member to be joined.

Based on the above embodiment, the result of actually forming a cemented cemented carbide is shown below.
As Example 1, a surface containing WC as a main component and 5% by weight of titanium carbide as a sintering aid, having a cylindrical shape with a diameter of 30 mm and a length of 50 mm, and the joint surfaces 3A and 5A represented by the maximum height. Cemented carbide members 3 and 5 having a finished surface with a roughness Ry of 5 μm were joined.
The bonding conditions at this time were such that a pressure in the vacuum chamber 8 was 3 Pa, a compressive force of 20 MPa, a pulse current of 300 Hz and 1500 A were applied, and a bonding temperature of 1300 ° C. was set.
Further, as Example 2, the cemented carbide members not containing the above-mentioned sintering aid were processed into the same shape, and a compression force of 50 MPa, a pulse current of 300 Hz and 1500 A were applied, and a joining temperature of 1500 ° C. Joined. Furthermore, as Example 3, the cemented carbide member including the sintering aid and the cemented carbide member not including the above-described sintering aid are compressed at 20 MPa, and a pulse current of 300 Hz and 1500 A is applied to join at a joining temperature of 1300 ° C. .

Further, as Example 4, instead of cemented carbide members, a cemented carbide member containing WC as a main component and 5% by weight of titanium carbide as a sintering aid, and the other as an alloy containing tungsten as a main component. A certain ambiloy (registered trademark) 1150 (composition: 90W-4Mo-2Fe-4Ni) or Inconel (registered trademark) 600 (composition: 76Ni-16Cr-8Fe) was joined. These are processed into a cylindrical shape with a diameter of 30 mm and a length of 50 mm, and the surface roughness of each bonding surface is finished to 10 μm. As bonding conditions, a compression force of 10 MPa, a pulse current of 300 Hz and 1500 A are applied, and a bonding temperature of 1100 is obtained. Joined at ℃.
As a result, the cemented cemented carbide formed in any of the examples was integrally joined with almost the same strength as the part where the joined part of the alloy member was not joined.

It is principal part sectional drawing which shows the discharge plasma sintering apparatus which joins the cemented carbide member which concerns on one Embodiment of this invention. It is sectional drawing which shows the joining cemented carbide alloy which concerns on one Embodiment of this invention. is there.

Explanation of symbols

2 Bonded cemented carbide 3, 5 Cemented carbide member (alloy member)
3A, 5A joint surface

Claims (7)

A method of joining alloy members, at least one of which is a cemented carbide member,
A bonding step in which the alloy members are directly contacted with each other at a bonding surface and a pulse current is applied while applying pressure between the two alloy members;
The cemented carbide joining method, wherein at least one of the alloy members is a cemented carbide member mainly composed of tungsten carbide (WC).   The cemented carbide joining method according to claim 1, wherein the pressure is 1 MPa or more and 100 MPa or less.   3. The cemented carbide joining method according to claim 1, wherein the other alloy member contains one of tungsten, nickel, and chromium as a main component. 4.   The cemented carbide joining method according to any one of claims 1 to 3, wherein the roughness of the joining surface is 10 μm or less in terms of a surface roughness Ry expressed by a maximum height.   5. The cemented carbide joining method according to claim 1, wherein the alloy member is heated to a temperature of 800 ° C. or more and 1600 ° C. or less during the joining step.   6. The cemented carbide joining method according to claim 1, wherein the heating is performed by pulse energization. A cemented cemented carbide in which at least one of the alloy members is a cemented carbide member,
A cemented cemented carbide which is joined by the cemented carbide joining method according to any one of claims 1 to 6.

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