Warm compaction is a forming technology which can produce high strength powder metallurgy parts at low cost. It has received extensive attention from the industry of tungsten carbide. Green-Pressing property directly reflects the quality of warm compaction, of which the machinability and mechanical property are two important performance indexes.

 

Machinability

The polymer not only has a certain toughness but also has a certain strength below the glass temperature. At the same time, the plastic deformation of powder is greater under warm compaction, resulting in more clean interfaces, allowing more powder contacts, which promotes mechanical bonding and metallurgical bonding of tungsten carbide powders. These factors make the density increase and the strength is increased, and the machining is possible, but also reduces the green in the handling process of damage.

 

 

When the strength of tungsten carbide green-pressing is more than 30MPa, it will have the ability of machining. It is not easy to achieve the required high billet strength (about 20MPa) by conventional powder metallurgy. The green-pressing which is made by warm compaction has a higher density. During warm compaction, the mixture is in the viscous flow state, which enhances the lubrication effect between powder particles in the pressing process, reduces the frictional resistance and fills the powder particles well. It can better transfer the pressing pressure, which is beneficial to the improvement of the strength of the blank. The strength of green-pressing can meet the requirement of machining through process control and selection of suitable polymers.

 

Mechanical Property

As the compact density increase, the strength of pressed compact has also increased. The compression strength of green-pressing can reach 15 ~ 30MPa, which is much higher than the product suppressed by traditional process. Because of the high sintering density, the yield strength can be increased by 11%. The ultimate tensile strength can be increased by 13.5%, the impact toughness can be increased by 33%, the apparent hardness and the elongation of material can also be improved due to the high sintering density.