The purpose of heat treatment of iron base powder metallurgy

The significance of heat treatment of powder metallurgy

The reducing iron powder is an important raw material for powder metallurgy, which is mainly used to produce powder metallurgy gear, oil bearing and other products.
The pressure embryo density of powder metallurgy is usually only about 6.5, and its hardness is low. In order to improve the hardness and fatigue strength of the product, heat treatment process is needed to achieve the purpose.

The reduced-iron powder metallurgy gear is the key structural part of the manual transmission.
Normally the powder metallurgy gear is subjected to pulse stress at meshing, and the peak stress peak is near the surface of the gear.
It is mainly surface or near surface that require high strength and high wear resistance.
Heat treatment is to improve the performance of the material by not changing the shape and size of the material, including performance and process performance, and improving the inner quality of the parts.
Therefore, the powder metallurgy gear can be treated by heat treatment to improve its surface hardness, strength and wear resistance.

Common heat treatment process

carburizing
Carburizing and carbonitriding, carburizing gas can penetrates through pore system of powder metallurgy parts material inside material, which can quickly absorb carbon, nitrogen, qualitative hard compound formation, through this method to improve the hardness of the products.

Chemical heat treatment
Chemical heat treatment and the difference carburizing heat treatment, chemical treatment, in addition to the organizational structure of the material change, also because of the other elements of infiltration, and parts of the surface layer material composition has changed.
Chemical heat treatment is aimed at changing the composition of the material surface layer, higher surface hardness and wear resistance, and at the same time improving the total iron base powder metallurgical parts material mechanical properties, especially the fatigue strength, therefore, chemical heat treatment is usually called surface hardening treatment.