Hard compound such as iron carbide (Fe3C) or the alloy carbides of chromium, vanadium, molybdenum and tungsten. In tool steels, undissolved primary carbides supply wear resistance, while the carbon and alloy dissolved at austenitizing supply hardness and secondary hardening on tempering. Carbide size, shape and spacing are set by prior annealing and austenitizing temperature, and coarse networks cut toughness.
D2 is loaded with chrome carbide, don't go hotter chasing hardness, you'll just dissolve it and keep retained austenite.
Also heard as
- alloy carbide
- primary carbide
Related terms
Cementite
Iron carbide, Fe3C: the hard, brittle compound that carries most of the carbon in slowly cooled steel.
Spheroidizing
Long holds near the lower critical temperature that turn carbides into small round particles.
Secondary hardening
A rise in hardness when certain alloy steels are tempered around 500 to 600 °C, from fine alloy carbides.
Austenitizing
Heating steel above its upper critical temperature and holding it until the structure becomes austenite.