JPS6037280A - Joining member for sintered hard alloy and steel and its production - Google Patents

Abstract

PURPOSE:To prevent cracking of a joining member and to improve the life of a forging punch, etc. in joining of a sintered hard alloy and a steel by forming >=1 layer of diffusion layer having a limited thickness between the sintered hard alloy and the steel. CONSTITUTION:A metallic filler 3 having <=0.3mm. thickness is forced into the space between a sintered hard alloy 1 and a steel 2 and while pressurizing force is exerted to the insertion surface, a high energy beam is applied to the sintered hard alloy side to form <=0.5mm. diffusion layer between the two materials, thereby joining the same. The metallic filler having 1,000 deg.C m.p. is preferred in this case. Mechanical strength is low if the m.p. is lower than value. It is also possible to obtain a thin alloy of the joint layer by using >=2 kinds of fillers having different m.p. An electron beam or laser beam is utilized as the high energy beam.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field) The present invention relates to a cold forging punch, a hot forging punch, a mold, etc. in which cemented carbide and steel are joined.

(Technical background) In general, cemented carbide is joined by soldering using Ag soldering etc.2
However, brazing materials tend to come off from the edges, so they are not put to practical use. These brazing materials are shaped firstly, and secondly, because there is a difference in thermal expansion coefficient between steel and cemented carbide, residual stress remains and becomes a source of crankshaft during repeated impact. .

Thirdly, since the compressive strength of the brazing material itself is low, there are problems such as deformation of the brazing material when an impact is applied. It has not been used. Recently, a joining method using a high-energy beam has been developed and is being put into practical use, but it has not yet been put into practical use in the field of forging punches, which require a large number of repetitions. The reason is that cemented carbide is susceptible to thermal shock, and steel undergoes transformation when heated to high temperatures. When joining with a high-energy beam, cemented carbide tends to crack due to thermal shock, and steel tends to crack due to a decrease in tensile strength due to transformation.

(Disclosure of Occurrence) The present invention was obtained as a result of intensive studies to solve these problems. The gist of this is that when joining cemented carbide and steel, a diffusion layer of 0.5 ffm or less is created between the two.
The present invention provides a cemented carbide and steel joining member formed of more than one layer. The second invention is to join cemented carbide and steel by inserting a metal filler with a thickness of 0.3 mm or less between the two, applying pressure to the insertion surface, and applying a high-energy beam to the cemented carbide side. The present invention provides a method of manufacturing a joining member of cemented carbide and steel that is joined together using a method of joining. The metal filler contains 10
It is desirable to have a melting point of 00°C or higher; below that, mechanical strength such as tensile strength is usually low. Further, as the high-energy beam, an electron beam or a laser beam is generally used and can be easily used. FIG. 1 shows the distribution of Ni when cemented carbide 1 and steel 2 are joined using Ni metal foil 3 of a similar thickness. The portion 4 indicates the width of Ni diffusion toward the cemented carbide, which in this example was approximately 10 μm, and the diffusion layer into the splintered steel portion was approximately 20 μm. When Ni was used as the metal filler, no phenomena such as decarburization were observed on the cemented carbide side. Another feature of the invention is that 0.3 mm
The following metal filler is inserted between the cemented carbide and the steel, the cemented carbide is directly heated with a high-energy beam, and the metal filler is inserted between the cemented carbide and the steel by simultaneously press-welding the cemented carbide and the steel. This bonding method is characterized by diffusion bonding. If the metal filler exceeds 03 strength, the metal filler will be compressed and deformed under the high load during use, so it will not be able to withstand forging pressure. The thickness of the filler is preferably 0.3 mm or less. 0.3
If it is less than mm, diffusion will occur in the cemented carbide and the steel, so the thickness will ultimately be less than half. More preferably, the thickness of the metal filler is 5μ or more and +00 t- or less. When the thickness of the metal filler is less than 5 μm, it is difficult to manufacture the metal filler, and the bonding strength after cracking becomes weak. A high-energy heat source is preferable for diffusion bonding. Since the high-energy beam can adjust the beam diameter and heat only a narrow area near the joint, deformation and transformation of the steel part can be minimized. It is better for the filler used in the present invention to have a melting point of 1000°C or higher. That is, as a method for joining cemented carbide and steel, which have excellent impact resistance, it is desirable to use a material with a high melting point and high tensile strength. For example, pure N
A material containing B, Si, Mn, Mg, etc. in i or Ni can be used, and many alloys such as pure Ca and Co1Ni can be used. For example, when Nii or N1 alloy is used, the role of this type of filler is to prevent the solid solubility of carbon in the cemented carbide and the bonded carbon from diffusing into the steel part, since the solid solubility of carbon is small. You can also. Alternatively, it is also possible to use a plurality of fillers with different properties. For example, by using two or more types of fillers with different melting points, it is also possible to obtain an alloy with a thin bonding layer. Furthermore, as mentioned above, thermal history tends to remain in the joints, and the cemented carbide, filler material, and steel may deteriorate due to thermal stress caused by thermal strain and temperature rise to near the melting point. There is also. For this purpose, for example, after joining,
It is also possible to perform heat treatment steps such as hardening, annealing, and tempering. In some cases,
In the case of electron beam welding, etc., it is also possible to control the cooling rate of the joining members by introducing an appropriate gas into the container. Conventional brazing joining methods have the disadvantages that the strength of the brazing material itself is weak, the heating area is wide, and the transformation range of the steel is wide. Also, conventional welding methods have similar problems. That is, because the heated area during bonding was extremely wide, the deteriorated layer was wide, and it was difficult to restore the original state even after heat treatment after bonding. The present invention is
In order to solve this problem, the thermally altered layer is thin and recovers easily.

EXAMPLE A cemented carbide of φ20×20 was welded to a 5KD61 steel material of φ20×150. Figure 2 shows vacuum chamber 6I.
A steel material 7 and a cemented carbide 8 were set inside the steel material, and a 50 μm Ni filler was inserted between the steel material and the cemented carbide.

The steel material was fixed with a rotating jig 9, and the cemented carbide was pressed with a pressurizing jig IO. By rotating the rotating jig 9, the steel and cemented carbide were pressurized with the force of simultaneous rotation without slipping. The inside of the chamber was evacuated to I O-'' Torr, an electron beam was generated from an electron gun, and the beam was applied to the carbide side 2 ym from the contact surface of the cemented carbide and steel to heat the cemented carbide. Beam conditions are +50 kv15mA
, and the heating rate was 100 ml/'min.

When a punch bonded by diffusion bonding using this method was used in a 5ii5C forged (300 ky/cr!), the life was 10 times longer than that of a die steel bench.

[Brief explanation of the drawing]

FIG. 1 shows a sectional view of a joining member obtained by the present invention. FIG. 2 is a schematic diagram of an electron beam welding device. 1... Cemented carbide, 2... Steel, 3... Metal filler, 4... Diffusion layer, 5... Diffusion layer, 6... Vacuum chamber, 10... 1st □ second dimension

Claims (1)

[Claims] +11 In joining cemented carbide and steel, there is no thickness between them.
．． A bonding member for cemented carbide and steel, characterized by forming one or more diffusion layers of 5 am or less. (2) When joining cemented carbide and steel, there is no thickness between the two.
A method for producing a joining member of cemented carbide and steel, which comprises inserting a metal filler of 3 mm or less and joining by applying pressure to the insertion surface. (3) The method for manufacturing a joining member of cemented carbide and steel according to claim (2), wherein the metal filler has a melting point of 1000° C. or higher. (4) Claim No. 3, characterized in that the high-energy beam is an electron beam or a laser beam.
Manufacturing method of cemented carbide and steel joining member described in Section 0