Main Properties of Cemented Tungsten Carbide

Tungsten carbide/cemented carbide is a kind of high hardness and brittleness material composed of refractory metal carbides, such as tungsten carbide powder or titanium carbide powder, and bonded metal cobalt, nickel or iron. It has excellent physical and chemical properties and is widely used in aerospace, aviation, navigation and other fields.

1、 Density

Density is a measure of the mass in a specific volume, equal to the mass of the object divided by the volume. Tungsten-cobalt cemented carbide density is 14.4~15.3g/m3, which generally decreases with the increase of cobalt content; The density of tungsten cobalt titanium carbide is 9.7~13.2 g/m3, which generally decreases with the increase of cobalt and/or titanium carbide content. In addition, when the chemical composition of the material is constant, the density of the alloy will decrease with the increase of the voids. The density is measured by the drainage method (Archimedes law).

2、 Hardness

Hardness refers to the ability of the alloy material to resist indentation deformation caused by other hard objects. The hardness of cemented carbide is generally 86~93HRA (equivalent to 69~81HRC). When the chemical composition or raw material ratio is different, the hardness of the alloy is also different, for example, YG6 is not lower than 89HRA, YG8 is not lower than 89.5HRA. Common hardness testing methods include Rockwell hardness (HRA) and Vickers hardness (HV).

3、 Bending strength

Bending strength refers to the ability of alloy materials to resist bending and continuous cracking. Generally, three-point bending test or four-point test method is used for evaluation. The factors affecting the bending strength of cemented carbide include the type of hard carbide and bonding phase, the content and particle size of hard carbide, sintering process, heat treatment process, structural defects and residual stress.

Under certain conditions, the bending strength of cemented carbide decreases with the increase of temperature; It increases with the increase of cobalt content (0~15%); It increases with the decrease of the average particle size of tungsten carbide; It increases with the uniformity of tungsten carbide particle size.

4、 Coercivity

Coercive force refers to the strength of the anti-magnetic field that completely demagnetizes the alloy after saturation magnetization; It increases with the decrease of tungsten carbide particle size, and decreases with the decrease of grain size after reaching a maximum value; It decreases with the increase of cobalt content; When the temperature rises to overburning, the coercivity of the alloy will also decrease. The coercive force test methods include the coercive force meter method, the DC hysteresis loop method and the impact method.

5、 Abrasion resistance

Abrasion resistance refers to the ability of a material to resist mechanical wear, which can be expressed by wear amount or wear index. The measurement methods include weight-loss method, size change emphasis method, surface morphology measurement method and scoring method. Generally speaking, the higher the content of hard carbide, the better the wear resistance of the alloy.

6、 Thermal and hard aspects

Thermohardness refers to the property that the alloy can maintain high hardness at high temperature. The hardness of cemented carbide can still be maintained at about 60HRC at 900~1000 ℃.

7、 Resilience

Toughness refers to the resistance of alloy materials to fracture when subjected to the force that causes deformation. The toughness of cemented carbide is mainly provided by the bonding phase.