How do you anneal a ferrous metal?

Answer 1

Annealing is the process of slowly raising the temperature about 50 ºC (90 ºF) above the Austenitic temperature.

It 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 ºC/hr (36 ºF/hr) in a furnace to about 50 ºC (90 ºF) into the Ferrite-Cementite range. At this point, it can be cooled in room temperature air with natural convection.

the process is used to soften the metal so that you can work on it without it fracturing or generally to make it more maliable.

In addition to the process above, you can also anneal metals as follows:-

Normalising: raised to 60 degrees, to completely convert the metal to Austenite.

Process: used on work hardened metals to return the soft maliability for further cold working without the metal fracturing.

Stress relief: reduces residual stresses in large castings

Spheroidisation: used to treat high carbon steels which are going to be machined or cold formed.