JP2855686B2 - Cemented carbide for wear-resistant tools - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to a cemented carbide for wear-resistant tools, for example, wear-resistant punches, cold forging tools such as headers, solid tools used for hot forging tools, etc. The present invention relates to the above alloy applicable to a tool having both toughness and wear resistance.

[Prior art] Conventionally, WC-
Co-based alloys have been used.

In this WC-Co alloy, wear resistance or toughness has been improved by a combination of WC grain size and Co amount.

[Problems to be Solved by the Invention] However, since the wear resistance and toughness are contradictory properties, in the WC-Co-based alloy described above, when Co is increased to impart high toughness, the wear resistance is inevitably increased. There is a disadvantage that the properties are reduced.

For this reason, the application of the WC-Co alloy as a tool for wear and impact resistance has been limited as compared with a high-speed (abbreviated for high speed) alloy.

Also, alloys in which Co is replaced with Ni or the like, or WC is replaced with (MoW) C have been studied. However, the essential problem had not been solved.

The present invention has been made in view of the above circumstances, and has as its object to provide a cemented carbide for a solid tool or the like having both wear resistance and toughness.

Means for Solving the Problems The present invention achieves the above object by providing a composite structure in which the amount of a binder phase in the vicinity of the surface of a WC-iron group metal cemented carbide such as a WC-Co alloy is changed. Is what you do.

That is, the present invention relates to a cemented carbide comprising WC as a hard phase and an iron group metal as a binder phase.
between 5 μm and 5-100 μm thick binder phase enriched layer is present,
The amount of the binder phase in the binder phase-enriched layer is 1.2
A region from the outer periphery of the binder-phase-enriched layer to the surface of the cemented carbide is a binder-phase-reduced layer in which the amount of the binder phase is reduced as compared to the inside of the alloy; A cemented carbide for wear-resistant tools, wherein the thickness of the binder phase reduction layer is within 1000 μm.

[Operation] The present invention is characterized by the following.

The cemented carbide has a binder phase-enriched layer in which the amount of binder phase between 10 and 1000 μm from the surface is 1.2 to 5 times that of the inside of the alloy.

The thickness of the binder-phase-enriched layer is preferably 5 to 100 μm.
m.

In the region from below the surface of the cemented carbide to the above-mentioned binder-phase-enriched layer, the amount of the binder phase is reduced as compared with the inside of the alloy, and the binder-phase-reduced layer is formed.

The toughness is imparted to the cemented carbide of the present invention by a layer in which the amount of the binder phase existing between 10 and 1000 μm from the alloy surface is enriched from 1.2 times to 5 times. If the region where the binder-phase-enriched layer (hereinafter also referred to as a toughening layer) is present is within 10 μm from the alloy surface, the toughening layer is exposed due to the progress of wear and the like. descend. Also 1000μm
If the inside of the alloy exceeds that of the alloy, the effect of the toughened layer is hardly exhibited.

On the other hand, if the thickness of the toughened layer is 5 μm or less, it is insufficient to exhibit the effect of improving toughness as a wear-resistant tool.
If it exceeds 100 μm, plastic deformation of the surface is caused, which is not preferable.

For the same reason, the amount of the binder phase in the toughened layer is preferably 1.2 to 5 times as large as that in the alloy. It is preferable that the larger the ratio, the smaller the thickness of the enriched layer.

On the other hand, abrasion resistance can be imparted to the portion from 10 to 1000 μm below the surface and to the outer peripheral portion (upper edge) of the binder-enriched layer. If it is a phase reduction layer (hereinafter sometimes referred to as a hardened layer), its toughness can be further improved. If the region of this hardened layer exceeds 1000 μm from the alloy surface, it leads to a decrease in toughness.
When the thickness is less than 10 μm, the binder phase reduction layer is apt to disappear due to abrasion, and the time for exhibiting the effect of imparting abrasion resistance is shortened.

The binder phase of the cemented carbide of the present invention includes iron group metals such as Co, Ni and Cr, and particularly preferably Co. The effect of the present invention can be obtained even if the binder phase is a solid solution of Co and Ni or a solid solution of Co, Ni and / or Cr.

As one of means for achieving the structure of the present invention, a method of pressing, forming, and sintering a press-bonded body having a different amount of binder phase as a laminate structure can be mentioned.

As another means, a method of repeating decarburization treatment and carburization treatment of a complete powder having the same composition in a liquid phase or a solid phase can be mentioned.

[Examples] Example 1 WC-10% Co bonded phase alloy complete powder in the center,
A) 12% Co, B) 20% Co, C) 40% Co, D) After loading 50% Co alloy complete powder, further charge 7% Co alloy complete powder around its outer periphery to obtain a predetermined punch shape. After pressing, it was sintered at 1360 ° C. in a vacuum atmosphere. By changing the filling amount, the first
Adjustment was made so as to have the structure shown in the table.

Using this alloy and 10% Co and 20% Co alloys for comparison, SCr (Cr steel) 21 was subjected to 58% cross-section reduction (rate of change in material area before and after processing) and extrusion length (extrusion processing). The length of the alloy was changed to 10 mm, and the alloy was subjected to a life test. As a result, the alloys A, B, C, and D of the present invention were capable of 80,000, 100,000, 300,000, and 250,000 shots, respectively, while the comparative 10% Co alloy was 0.1000 shots. The 20% Co alloy had a wear life of 10,000 pieces.

Example 2 In the composition of the alloy B of Example 1, the thickness of the toughened layer was changed to E) 5 μm, F) 20 μm, G) 60 μm, H) 100 μm.
The test of Example 1 was performed as m. As a result, the alloy
E, F, G, H could shoot 30,000, 80,000, 280,000 and 270,000 shots.

[Effects of the Invention] As described in detail above, in the alloy of the present invention, the contradictory properties of wear resistance and toughness are exhibited near the surface of the alloy.
By changing the amount of the iron group metal binding phase such as Co, it can be highly imparted.

As a result, the use of iron group metal-based alloys such as WC-Co as wear-resistant and impact-resistant tools can be expanded to be equal to or higher than that of high-speed alloys, and the present invention provides both wear resistance and toughness. It is useful as a cemented carbide for a solid tool that also has a function.

Claims (1)

(57) [Claims] 1. A cemented carbide comprising WC as a hard phase and an iron group metal as a binder phase, wherein a binder phase enriched layer having a thickness of 5 to 100 μm exists between 10 and 1000 μm from the surface of the alloy. The amount of the binder phase in the binder-phase-enriched layer is 1.2 to 5 times as large as the inside of the alloy, and the region from the outer periphery of the binder-phase-enriched layer to the surface of the cemented carbide is alloyed. A cemented carbide for a wear-resistant tool, characterized in that the binder phase-reduced layer has a reduced binder phase amount as compared to the inside, and the thickness of the binder phase-reduced layer is within 1000 µm.