JPH07138690A - Hyperfine-grained hard alloy and parts - Google Patents

Abstract

PURPOSE:To obtain an hyperfine-grained hard alloy having superior toughness and high strength by specifying a composition consisting of hard material, such as VC, of specific grain size, iron group metal as binding metal, and hyperfine-grained WC of specific grain size. CONSTITUTION:This alloy is an hyperfine-grained hard alloy having a composition consisting of <=10% of one or more kinds among VC, Cr3C2, TaC, ZrC, SiC, MgO, Si3N4, diamond, and CBN, having an average grain size of <=3mum, preferably <=1mum, 0.5-40% of iron group metal, and the balance WC of <=0.1mum average grain size with inevitable impurities. This alloy has superior strength and toughness. By using this alloy, thin-walled dies suitable for anvil for super high pressure use, small-diameter punch, small-diameter drill, diver cutting, resin cutting, etc., excellent in pressure resistance, wear resistance, long life, micro-pitting resistance, breaking resistance, etc., can be obtained.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a hard alloy excellent in strength and toughness and its use.

[0002]

2. Description of the Related Art WC-based cemented carbide is an excellent material having both strength and toughness and is widely used in industry. Above all, the so-called ultra-fine grained alloy having an average grain size of WC of about 0.5 μm is a material having excellent hardness and HRA93, and a bending strength of 35 kgf / mm ² or more, which is an extremely high value and has excellent toughness. However, when this ultra-fine grained alloy is used for parts such as ultra-high pressure anvils, small-diameter punches, small-diameter drills, diver cuts, resin cuts, and other thin-walled mold parts, cracks often occur due to insufficient strength and lack of toughness. Occur.

The object of the present invention is to provide a material having a higher toughness than the current ultra-fine grained alloy, especially for thin wall molds such as ultra high pressure anvils, small diameter punches, small diameter drills, diver cuts and resin cuts. It is to provide a component having excellent reliability even when there is a problem.

[0004]

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention The present invention has been made as a result of extensive studies on the improvement of the toughness of the existing ultrafine grained cemented carbide. That is, by using WC having an average particle diameter of 0.1 μm or less, which has been difficult to use for various reasons in the past, the transverse rupture strength of the ultrafine grained cemented carbide is remarkably improved. The reason why it is difficult to use conventionally is that (1) since the WC of the raw material powder is ultrafine powder, it is easily ignited. (2) There is a large difference between the particle size of WC of the raw material powder and the particle size of the other raw material powder, and it is difficult to sufficiently mix them. (3) It is difficult to obtain WC powder having an average particle size of 0.1 μm or less. And so on.

[0005]

[Means for Solving the Problems] The inventor has studied improvement measures for these points, and as for (1), by performing a manufacturing process in an inert atmosphere or coating a very small amount of wax on the powder surface in advance. I was able to avoid the fire. (2) The difficulty of mixing could be solved by optimizing the mixing conditions and using an appropriate surfactant. Regarding (3), powder manufacturing technology has been improved in recent years, and it is relatively easy to obtain. As a result of examining various material compositions based on the above technical background, although the hardness shows a high value of HRA94, the transverse rupture strength is 45
An extremely tough material with 0 kg / mm ² or more was created.

[0006]

FUNCTION Here, it is desirable that the particle size of WC is 0.1 μm or less. If it exceeds 0.1 μm, the transverse rupture strength decreases, and for example, for ultrahigh pressure anvils, small diameter punches, small diameter drills,
When used for thin molds such as diver cut and resin cut, excellent reliability cannot be guaranteed. The iron group metal used as the sintering binder is 0.5 to 40% by weight. If it is less than 0.5, the effect as a binder is weak and the toughness is not sufficient. If it exceeds 40%, the strength is insufficient and it cannot be used for the above-mentioned applications.

As a hard substance other than WC, the average particle size is 3 μm.
m or less, preferably 1 μm or less of VC, Cr ³ C ² , Ta
C, ZrC, SiC, MgO, Si. N 4, diamond, and C
It is essential to use one or more selected from BN. If the average particle size exceeds 3 μm, uniform dispersion becomes difficult, and it becomes a starting point of fracture, etc., so that the toughness decreases and it is difficult to put it to practical use. The average particle size is preferably 1 μm. The uniformity is improved, and the probability of becoming the starting point of fracture is reduced, so the toughness is greatly improved. The addition amount is 10% by weight or less. If it exceeds 10%, the characteristics as an ultrafine grained alloy will be diminished and the transverse rupture strength will be markedly reduced.

Hard materials include VC, Cr ³ C ² and Ta
C, ZrC, SiC, MgO, Si ³ N ⁴ , diamond and C
One or more selected from BN. As is well known in the current cemented carbide, the substance does not impair the sinterability and has the effect of improving hardness, corrosion resistance, oxidation resistance, strength and the like. When the ultra-hard material according to the present invention is used as a thin die such as an anvil for ultra-high pressure, a small-diameter punch, a small-diameter drill, a diver cut, or a resin cut, the effect is great. When used as an ultra-high pressure anvil, it can withstand higher pressure than before. When used for small-diameter drills and small-diameter punches, chipping is reduced, wear resistance is improved, and tool life is extended. When used as a thin die for diver cutting, resin cutting, etc., microchipping and chipping of the die are reduced and wear of the die is reduced.

[0009]

EXAMPLE WC powder, hard substance powder and iron group powder were blended in a predetermined ratio and mixed using an attritor in an inert atmosphere. Alcohol and a trace amount of surfactant were used for mixing. After mixing for a predetermined time, spray drying was performed in an inert atmosphere to dry the solvent. The dried mixed powder was press-molded and sintered in vacuum under appropriate temperature conditions. After sintering, it was processed into a predetermined shape and various material properties were measured. The results are shown in Table 1.

[0010]

[Table 1]

Next, various parts were produced using the material of the present invention and evaluated. The results are shown in Table 2.

[0012]

[Table 2]

[0013]

EFFECTS OF THE INVENTION The present invention significantly improves the toughness of conventional ultrafine-grained cemented carbides and is of great practical significance.

Claims (2)

[Claims] 1. An average particle size of 3 μm or less, preferably 1 μm
VC, Cr ₃ C ₂ , TaC, ZrC, SiC, MgO,
One or more selected from Si ₃ N ₄ , diamond and CBN is 10% or less, iron group metal is 0.5 to 40%, and the balance is WC having an average particle size of 0.1 μm or less and unavoidable impurities. Ultra-fine grained hard alloy. 2. A component for use in a thin mold such as an anvil for ultrahigh pressure, a small diameter punch, a small diameter drill, a diver cut, a resin cut, etc., which is made of the ultrafine grained hard alloy according to claim 1.