Heat Treating Cast Iron
Cast iron has plenty of carbon available and is easy to heat treat.
Both gray and ductile cast iron does not have to be carburized prior to heat treating because it is made up of at least 2.5% carbon.
Iron and steel grow when heat treated because of the volume change in the atomic structure.
- 550 to 650°C - Stress relief without significantly lowering strength and hardness.
- 700 to 760°C - Lowers the hardness for improved machinability.
Ferritizing (for the most ductile microstructure) is done by austenitizing at 900°C, followed by holding at 700°C to completely transform austenite to ferrite and graphite.