JPS6311646A - Tungsten carbide-base cemented carbide for cutting tool - Google Patents

Abstract

PURPOSE:To improve chipping resistance by incorporating VC together with Co at a specific ratio into WC and confining the grain size of a hard dispersed phase to a specific fine range. CONSTITUTION:This cemented carbide contains, by weight, 5-20% Co and 0.2-10% VC, consists of the balance WC and has the fine structure in which the average grain size of the hard dispersed phase constituted of components except Co is 0.2-1mu. The alloy has particularly excellent chipping resistance and excellent wear resistance as well. The Co forms a binding phase in said alloy and is indispensable to assure the toughness of the alloy. The toughness is not enough if the content thereof is <5%, while the wear resistance is low if the content exceeds 25%. The VC contributes to the remarkable improvement in the chipping resistance without impairing the wear resistance. The desired effect is not obtainable if the content thereof is <0.2%, while the wear resistance is low if the content exceeds 20%. It is technically difficult to form the hard dispersed phase to <0.2mu average grain size, while the chipping resistance is sharply deteriorated if the grain size exceeds 1mu.

Description

[Detailed Description of the Invention] [Special Field of Application] The present invention provides 1 tungsten carbide (hereinafter referred to as "tungsten carbide") which exhibits not only wear resistance but also excellent chipping resistance when used as a cutting tool such as an end mill or a drill.

This relates to cemented carbide (denoted as WC).

[Conventional technology]

In general, for the manufacture of cutting tools such as end mills and drills, 1% is 1%, and % below C indicates %% heavy.

Co: 5-2596° TaC* One or more of NbC+ and TiC: 0
．． WCC cemented carbide is used, which has a composition of 2 to 296 degrees, with the remainder consisting of WC and unavoidable impurities.

[Problem that the invention seeks to solve]

However, although the above-mentioned conventional WCC cemented carbide shows excellent wear resistance when used as a cutting tool, it currently does not show satisfactory results in fracture resistance.

[Means for solving problems]

Therefore, the inventors of the present invention, etc., from the above-mentioned viewpoint.

Focusing on the above conventional WCC cemented carbide, we conducted research to develop a WCC cemented carbide for cutting tools that has excellent not only IM wear resistance but also chipping resistance.

In place of TaC, NbC, and TiC contained as alloy components in the above-mentioned conventional WCC cemented carbide.

In addition to containing charcoal and hypanadium (V(l), C.

Conventionally, WCC cemented carbide had an average particle size of 1.5 to 5 μm, but if the average particle size of the hard dispersed phase composed of other components is set to 0.2 to 1 μm, the fracture resistance will be significantly improved. The knowledge that it also has excellent abrasion resistance? I got it.

This invention was made based on the above findings.

Co: 5-20%.

VC: 0.2~1096°? The remainder consists of WC and unavoidable impurities, and the hard dispersed phase composed of components other than Co has a microstructure with an average particle size of 0.2 to 1 μm. In particular, WCC cemented carbide for cutting tools has excellent fracture resistance and wear resistance.

Next, in the WCC cemented carbide of the present invention, the fractional composition and the average particle size of the hard dispersed phase in the dish limited as described above will be explained.

A. Partial composition (a) C.

The cobalt acid component forms a binder phase and is an essential component for ensuring the toughness of an alloy. If the total content is less than 5%, the desired toughness cannot be secured; on the other hand, if the content is less than 25%, If it exceeds this, the abrasion resistance decreases, so the plaster content was determined to be 5 to 2,596.

(b) VC The VC component has the effect of significantly improving the fracture resistance of Alloy 5 without impairing its wear resistance.

If the content [1 is less than 0.2%, the desired effect of improving fracture resistance cannot be obtained, while if the content exceeds 20%%,
This is because the wear resistance decreases.

8B whose content is defined as 0.2 to 2096 Average particle size of hard dispersed phase WC-based super superalloy in which the average particle size of hard dispersed phase is less than 0.2 pm? It is technically difficult to manufacture [2], and on the other hand, if the average particle size exceeds 1 μm, the fracture resistance will decrease rapidly, so the average particle size was reduced to 0.2 μm.
The distance was determined to be ~11m.

〔Example〕

Next, a WCC cemented carbide example of the present invention will be specifically explained.

As raw material powders, WC powder and VC powder each have an average particle size tW within the range of 0.2 to 1.0 μm.

TaC powder, NbC powder, TiC powder, and CO powder were prepared, and each of these raw material powders was blended into the composition shown in Table 1, mixed in a ball mill, and then molded into a rod-shaped green compact. , then these green compacts f I
By sintering in a vacuum of 10-2+nHg at a predetermined temperature within the range of 1330 to 1450°C and maintained at IF￥F, a selvedge with substantially the same composition as the blended composition and diameter: 6 WCC cemented carbide of the present invention with dimensions of .5swX length: 51#~91 Comparative WC-based cemented carbide 1~5,
and conventional WCC cemented carbide ~4 were crushed.

Next, from the WC-based cemented carbide of each heel obtained as a result,
By polishing, I made a two-sided end mill with a diameter of 6m x length of 50mm and a helix angle of 45mm, and used this.

Broken material: 5KD61 (hardness: HRC33).

Cutting connection: 30m/m.

Sending i): 0. O15■/blade, Cut depth: 61 m deep x 0.5 m wide.

Cutting length: 50m.

Cutting oil: A side cutting test was conducted on high-speed steel material under the following conditions, and the outer peripheral wear width of the end mill was measured after the test. The results of these tests are shown in Table 1. Table 1 also shows the average particle size of the hard dispersed phase.

〔Effect of the invention〕

From the results shown in Table 1, the comparative WC without VC
C cemented carbide, a ratio in which the Co-containing [1 is lower than the range of the present invention; a WC-based superbase hard alloy and a ratio in which the average particle size of the hard dispersed phase is higher than the range of the present invention; 4i1
2WC-based cemented carbide 5 has poor fracture resistance and breaks during the test, while comparative WCC cemented carbide 4 has high VC and co acid content outside the scope of the present invention. Although there is no occurrence of fleas, it is a product with poor wear resistance (flea).
, furthermore, the average particle size of the hard dispersed phase is relatively high, which is outside the scope of the present invention, and T is used instead of VC as an alloy component.
Conventional WCC cemented carbide ~4 containing one or more of aC* NbC* and Tic all break due to lack of fracture resistance under the above severe conditions, None of the WCC cemented carbides of the present invention ~ 9 broke during the test.

Not only does it exhibit excellent fracture resistance, but it also exhibits excellent ifl properties.
It is clear that it also exhibits wear resistance.

As mentioned above, when the WCC cemented carbide of the present invention is used as a cutting tool, it exhibits excellent wear resistance and chipping resistance, and exhibits extremely excellent cutting performance. .

Claims (1)

[Claims] A composition containing Co: 5 to 20%, vanadium carbide: 0.2 to 10%, and the remainder consisting of tungsten carbide and unavoidable impurities (wt%), and the above components other than Co. The average particle size of the hard dispersed phase is 0.2 to 1μ.
A tungsten carbide-based cemented carbide for cutting tools with excellent fracture resistance, characterized by having a microstructure of m.