After compaction the components must be sintered to give them the required properties.
Sintering provides the final mechanical properties, while both the magnetic properties (for soft magnetic components) and the corrosion resistance of stainless steel components can also be considerably affected.
Sintering is usually performed in a belt conveyor furnace in a controlled atmosphere.
Sintering is a type of heat treatment which normally is carried out at a temperature a few hundred degrees below the melting point of the base material. Thus, steel is generally sintered at 1120 °C.
During sintering the powder grains in the components grow together through a process of atomic diffusion and the final properties emerge.
Apart form minor sintering shrinkage the component geometry formed during compaction is retained.
Sintering is performed under a gaseous shield and under precisely controlled conditions in a furnace consisting of a preheating zone (where the lubricant in the powder mixture is expelled), a sintering zone and a cooling zone.
Sintering brings to an end the basic powder metallurgical process.
Depending on the requirements placed for the finished components, they are often subjected to one or more after-treatment processes.