Iron carbide

Chemical compound of iron and carbon (Fig. 1) at a ratio of 3:1 (Fe3C).

The metallographic designation of this structure component with a mass content of 6.7 % C is cementite. In iron and steel alloys, an increasing carbon content also leads to an increasing content of iron carbide in the structure. Hardness and strength of a material are respectively increased, flexibility, toughness and forming properties are reduced.

The distribution of the iron carbide has an additional influence on the mechanical properties in the material structure (fig. 2).

Additional references:
Iron-carbon phase diagram
Structure formation of cast iron
Carbide former
Carbidic cast iron
Titanium carbide

  • Fig. 1: SEM image of iron carbide in nodular graphite cast iron. The inclusions in the cementite are titanium carbonitrides
  • Fig. 2:  Grain boundary carbides (cementite) magnification 300:1, etched with HNO3