Full Annealing

Full Annealing:
  • In full Annealing the steel is heated above the critical temperature and then cooled very slowly.
  • In full Annealing steel is heated to its 500C above the austenitic temperature and held for sufficient time to allow the material to fully form austenite or austenite-cementite grain structure. The material is then allowed to cool slowly so that the equilibrium microstructure is obtained.
The Purpose of Full Annealing:
  • to relieve internal stresses 
  • to reduce hardness and increase ductility 
  • for refining of grain size 
  • for making isotropic in nature in mechanical aspects  
  • for making the material having homogeneous chemical composition 
  • for making the material suitable for high machining processes 
  • to make steel suitable for undergoing other heat treatment processes like hardening, normalizing etc. 
  • the grain structure has coarse pearlite with ferrite or cementite (depending on whether hypo or hyper eutectoid). The steel becomes soft and ductile.

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