Iron carbide containing 6.67 percent carbon by weight. It forms the plates in pearlite, grain-boundary networks in hypereutectoid steels and over-carburized cases, and the rounded particles of a spheroidized structure. A continuous cementite network at the prior grain boundaries makes high-carbon steel brittle, so cycles are designed to break it up or avoid forming it.
Case shows grain-boundary cementite on the tooth tips, knock the boost carbon down before the next lot.
Also heard as
- iron carbide
- Fe3C
Related terms
Pearlite
A layered mix of ferrite and cementite that forms when austenite cools slowly through the eutectoid range.
Carbide
Any hard compound of carbon with iron or alloying elements such as chromium, vanadium, molybdenum or tungsten.
Spheroidizing
Long holds near the lower critical temperature that turn carbides into small round particles.
Carburizing
Diffusing carbon into the surface of low-carbon steel at high heat, then quenching for a hard case.