JPH028833B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for completely joining a plurality of cemented carbide members to produce large-sized parts or complex-shaped cemented carbide members.

Cemented carbide has high hardness and wear resistance, and is used in various industrial applications. As applications expand, the demand for large parts and parts with complex shapes is increasing, but it is not possible to meet these demands with normal powder metallurgy technology alone. This is done in advance by making them and then joining them together. However, joining this cemented carbide is extremely difficult due to the high melting point and high hardness of the cemented carbide.
There is a method of bonding by heating to a temperature of 1,300 to 1,500°C and applying pressure to cause mutual diffusion at the bonding surface. However, in this case, since the entire material is pressurized at high temperatures, the cemented carbide itself may be deformed or diffusion may be insufficient, making it difficult to achieve complete bonding. In addition, when manufacturing large products, there was a problem in that the pressurizing device became large.

The inventors of the present invention have conducted extensive research to solve these problems and respond to the above-mentioned demands for larger sizes and more complex shapes, and have found that the method of the present invention is extremely effective.

The feature of the present invention is that a thin metal plate 3 is inserted and brought into close contact between the contact surfaces 1' and 2' of the cemented carbide members 1 and 2, as shown in FIG. After welding and joining by irradiating energy beam A and melting it, we heat it to a temperature of 1350° to 1500°C in a vacuum or inert gas to diffuse the metal present at the joint surface into the cemented carbide. It is to let Another method of the present invention is to manufacture bonded cemented carbide members welded and bonded as described above, and then to use a hot isostatic pressing device (HIP).
1350℃ under pressure of 1000~2000Kg/ ^cm2
This method involves diffusion bonding at a temperature of 1500°C to obtain a completely integrated cemented carbide member.

The metal plate inserted into the joint surface has a thickness of 0.1 to 1 mm.
A thin plate of Ni, Co, etc. is used. If the thickness is less than 0.1 mm, the diffusion after joining will be insufficient and the cemented carbide will be damaged, and if it is more than 1 mm, the diffusion distance will be long and the hardness and strength of the joint will be insufficient compared to cemented carbide.

FIG. 2 is a schematic cross-sectional view of a joint to explain the state of diffusion that occurs during heat treatment after welding.
4 is a hard phase such as WC, 5 is a bonding phase such as Co, and 3 is an inserted metal plate, and by heating or pressure heating, WC and Co in the cemented carbide become the bonding phase, and the bonding phase Ni, etc., interdiffuse into the binder phase of the cemented carbide. At temperatures between 1,350℃ and 1,500℃, a liquid phase is generated in the cemented carbide, and WC dissolves in the Co phase, which is the bonding metal, and diffuses to the Ni side, and at the same time, the Ni in the bonding phase diffuses into the cemented carbide. The bonding phase 3 is then reduced and a complete bonded body can be obtained.

It is preferable that the high-energy beam used in the method of the present invention has a narrow beam diameter, such as an electron beam or a laser beam. This is because the beam penetrates deeply into the joint and can join without damaging the cemented carbide body.

Furthermore, when welding with a high-energy beam, it is not necessary to melt the entire surface of the welding phase, and only the outer periphery of the contact surface may be welded. Figure 3 shows an example of this. In the cross section of the joint in Figure 3, 7 is the abutment surface of the cemented carbide, and the outer periphery 6 is where a thin metal plate is inserted and brought into close contact with each other and then irradiated with an electron beam or the like and melted. This is the welding surface that will be welded at least. Welding in this condition,
By heating at a temperature of 1400℃ or higher, Co
The mutual diffusion of WC and Ni is sufficient to achieve the purpose.

The temperature range for heating after welding is preferably from 1320℃ to 1500℃. At temperatures below 1320°C, sufficient liquid phase is not generated and diffusion is difficult to proceed. Furthermore, at temperatures above 1500°C, the cemented carbide deforms, absorbs gas in the atmosphere, or carburizes, making it difficult to maintain good properties of the cemented carbide.

Next, an example will be described.

Example 1 WC-20% Co cemented carbide ring (outer diameter 600φmm,
When manufacturing a large product with an inner diameter of 500 mmφ and a thickness of 30 mm, the final shape was divided into four parts (Fig. 4, 9,
9′, 9″, 9) cemented carbide was manufactured. After polishing the contact surfaces 8, 8′, 8″, 8, they were combined into a ring shape, and a 0.5 mm Co thin plate was attached to each contact surface. This was then irradiated with an electron beam at 150KV and 30mA to weld the top and bottom surfaces with a beat depth of 15mm. Thereafter, heating was performed at 1450° C. for 1 hour in a vacuum (10 ⁻³ Torr). The resulting cemented carbide is completely bonded and has the same strength as one made without welding.

Example 2 As shown in FIG. 5, a cylindrical cemented carbide member 10 and a rectangular plate cemented carbide member 11 are manufactured in advance, and after polishing their contact surfaces, the contact surface 12 is coated with 0.2 mm
A thick Ni thin plate was inserted and brought into close contact, and the contact surfaces were welded using the electron beam shown in Example 1. This bonded member was heated at 1350°C for 1 hour using a hot isostatic press.
They were heated under pressure in an Ar gas pressure of 1000 Kg/cm ² to cause interdiffusion. The bonded surfaces were completely integrated, and a bonded cemented carbide member with no blowholes or cracks was obtained.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view for explaining the principle of the method of the present invention, FIG. 2 is an enlarged cross-sectional view of a joint, FIG. 3 is a cross-sectional view of a joint showing another embodiment of the present invention, and FIG.
FIG. 5 is a top view and a cross-sectional view showing an embodiment of a cemented carbide having an irregular shape produced by the method of the present invention. 1, 2, 9, 10, 11; Cemented carbide member, 3;
Metal thin plate, 4; hard phase, 5; bonding phase, 6; welding surface, 1', 2', 7, 8', 12; joint surface.

Claims (1)

[Claims] 1. A thin metal plate is inserted into the contact surfaces of a plurality of cemented carbide members, and the metal plates are irradiated with a high-energy beam to melt the metal plates, and the liquid phase of the cemented carbide is melted. A method for joining cemented carbide, which is characterized by heating above the formation temperature (1320°C) to cause interdiffusion between the metal phase of the metal plate and the cemented carbide, and then solidifying. 2 A metal plate is inserted into the contact surfaces of a plurality of cemented carbide members, and the metal plates are irradiated with a high-energy beam to melt and solidify the inserted metal plates to preliminarily join them. A super hard alloy characterized by heating the alloy member under pressure in a hot isostatic pressure device above the liquid phase formation temperature of the cemented carbide (1320°C) to cause mutual diffusion between the joint metal and the cemented carbide. Hard metal joining method. 3. A method for joining cemented carbide according to claims 1 and 2, characterized in that the high-energy beam is an electron beam or a laser beam. 4. A method for joining cemented carbide according to claims 1 and 2, characterized in that the metal plate inserted into the contact surface has a thickness of 0.1 to 1 mm.