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 ultrafine grained steels
through severe plastic deformation and heat treatment .
Pearlite, consistingof a-Fe and lamellar cementite (y), is one of
the most important structures in steels.Subtle cementite particles
are used to refine the ferrite grains and form(aþy) micro-duplex
structures, which can enhance the properties of pearlite steels.
Therefore, thecoarseningbehaviorandsizecontrolofthe y
particles are very important for obtaining the(aþy) micro-
duplex structures in steels.The conventional spheroidization
process of steel consists of asubcritical annealing treatment that
takes alongtime [7–9]. It is difficult to formultra-fine ferrite
grains and subtle cementite particles in steels during along
period of subcritical annealing.Generally,the most efficient
method of obtaining subtle cementite particles in pearlitic
steels comprises a combination of severe cold deformation and
annealing [1–3], heavy warm deformation [4–6], and cyclic heat
treatment