Normalizing, which is also called normalizing, is a metal heat
treatment process that is heated to Ac3 or more than Accm at 30~50 C.
After a period of heat preservation, it is removed from the furnace in
the air or by water spray, spray or blow cooling. The aim is to refine
the grains and homogenate the carbide distribution. The difference
between normalizing and annealing is that the normalizing cooling rate
is slightly faster than that of annealed cooling, thus the normalizing
tissue is finer than the annealed tissue, and its mechanical properties
are also improved. In addition, the cooling outside the normalizing
furnace does not occupy the equipment and has higher productivity.
Therefore, normalizing is used instead of annealing as far as possible
during the production. It is used for ductile iron to improve hardness,
strength and wear resistance, such as crankshaft, connecting rod and
other important parts for automobile, tractor, diesel engine. The aim is
to reduce the hardness and improve the machinability, eliminate the
residual stress, stabilize the size, reduce the deformation and crack
tendency, refine the grain, adjust the structure and eliminate the
defects of the tissue.