Create a more uniform grain structure
Normalizing is similar to conventional annealing, except
that when the heating cycle is complete, the furnace is opened and
are allowed to cool in still air. This causes a more rapid cooling
of the parts, leaving them still with a more uniform grain structure
but one that is generally harder and stronger than with annealing.
Normalizing is very common for pressure vessel plate grades like
A516, where the uniform structure and higher mechanical properties
This process is also applied to certain lower carbon alloy grades
that would be too soft to machine if annealed.