Superfine crystal tungsten carbide is a kind of hard alloy with the grain size of WC < 0.5μm (< 0.2μm for nanometer tungsten carbide). It has become an ideal material for high efficiency and precision cutting tools and PCB bits because of its excellent properties, such as high strength and high hardness.

 

When the grain size of WC is reduced to submicron, the hardness, wear resistance, strength and toughness of the tungsten carbide materials are improved. Compared with other hard alloy with larger WC grain, it has the characteristics of higher hardness, flexural strength of fracture toughness, and high temperature hardness.

 

 

1, Hardness

Compared to the non-superfine crystalline tungsten carbide with the same composition, the hardness of the superfine crystalline cemented carbide will increase to a certain extent, and the HRA will be higher than the 1.5-2. When the grain size of WC decreases to submicron, the hardness of the tungsten carbide is inversely proportional to the grain size of the material.

 

2, Fracture Toughness

The defects in the microstructure of ultrafine crystalline powder are small, which is beneficial to the improvement of the fracture bremsstrahlung of the alloy. Compared with coarse grain tungsten carbide, the grain boundary number of superfine crystal cemented carbide is more, and the crack propagates faster along the interface.

 

Crack of traditional tungsten carbide is extended along the grain boundary, which is possible to pass through the bond phase to form a dense and shallow dimple. When cracks propagate along the interface, a lot of plastic strains will be produced. Ultrafine grained cemented carbide will generate more fracture energy when the crack expands along the interface because of more interfaces. When the grain size of the material is very small, the relationship between the fracture toughness and the hardness of the material may be nonlinear.

 

3, Flexural Strength

Superfine crystal tungsten carbide has excellent bending strength and can reach more than 4000MPa, which is far higher than the 2000-3000MPa of conventional tungsten carbide. The steel bonded carbide die steel bonded carbide is between tool steel and hard alloy. It can be machined, forged and heat-treated, so it is widely applied to mould materials. The strength and toughness of steel bonded cemented carbide are generally higher than those of other cemented carbide, and maintain all the advantages of titanium carbide hard alloy, such as dry friction, small friction coefficient, high resistance to adhesion and wear.