Grains refinement, which can simultaneously enhance strength
and toughness of materials,is an important approach in developing a new generation of high-performance materials. Several
methods have been developed to obtain ultra fine grained steels
through severe plastic deformation and heat treatment .
Pearlite, consisting of a-Fe and lamellar cementite(y), is one of
the most important structures in steels.Subtle cementite particles
are used to refine the ferrite grain sand form(aþy) micro-duplex
structures, which can enhance the size control of the y
particles are very important for obtainingthe(aþy) micro-
duplex structures in steels.The conventional spheroidization
process of steel consists of a subcritical annealing treatment that
takes along time . It is difficult to formultra-fine ferrite
grains and subtle cementite particles in steels during along
period of subcritical annealing.Generally,themostefficient
method of obtaining subtle cementite particles in pearlitic
steels comprises a combination of severe cold deformation and
annealing heavy warm deformation and cyclic heat
treatment