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Annealing is one of the heat treatment process
in which the metal is heated to a temperature
above its recrystallization temperature, kept at
that temperature some time and then very slow
cooling to develop equilibrium structure in the
metal or alloy.
Annealing is a heat treatment that alters the
physical and sometimes chemical properties of a
material to increase its ductility and to make it
Annealing process consists of three stages such as–
3. Grain Growth
No change occurs in microstructures.
It occurs at low temperature.
During this point defects are created.
Dislocations of opposite sign come together
annihilate each other.
Point imperfections and dislocations are
associated with strain energy.
Strained grains becomes stress free, strain free
Microstructure at the end of recrystallization is
much similar to the original structure prior to the
Recrystallization temperature- The temperature
at which the normal cold worked material
recrystallizes in one hour.
Recrystallization temperature is high in case of
metal having high melting point.
Recrystallization temperature - Iron-450oc
Degree of cold work
Initial Grain size
Temperature of Cold Working
Purity or composition
It occurs due to the heating the
metal beyond the time given for
Diffusion occurs between grain
This results in increase in grain
Due to Grain growth larger
grains reduces the strength and
toughness of metal and curve
boundary becomes planar.
Grain growth is useful for single
Fig-2 Changes in Microstructure during
different stages of Annealing
Fig-3 Schematic Representation of cold worked and Anneal cycle
showing the effects of Properties and Microstructures
Textbook of Material Technology by O.P. Khanna