Annealing

Full industrial annealing solutions, annealing services is the process of slowly raising the temperature about 50 °C (90 °F) above the Austenitic temperature line A3 or line ACM in the case of Hypo eutectoid steels (steels with 0.77% Carbon) and 50 °C (90 °F) into the Austenite-Cementite region in the case of Hypereutectoid steels (steels with > 0.77% Carbon).

Aneealing is held at this temperature for sufficient time for all the material to transform into Austenite or Austenite-Cementite as the case may be. It is then slowly cooled at the rate of about 20 °C/hr (36 °F/hr) in a furnace to about 50 °C (90 °F) into the Ferrite-Cementite range. At this point, it can be cooled in room temperature air with natural convection.

The grain structure has coarse Pearlite with ferrite or Cementite (depending on whether hypo or hyper eutectoid). The steel becomes soft and ductile.