TITLE:
Recrystallization Kinetics and Microstructure Evolution of Annealed Cold-Drawn Low-Carbon Steel
AUTHORS:
Nurudeen A. Raji, Oluleke O. Oluwole
KEYWORDS:
Drawn Steel; Recovery; Recrystallization; Microstructure; Hardness; Soaking Time
JOURNAL NAME:
Journal of Crystallization Process and Technology,
Vol.3 No.4,
October
31,
2013
ABSTRACT: The recrystallization behavior of
cold-drawn 0.12 wt%
C steel during annealing at temperatures 600°C and 650°C was investigated.
Hardness tests were used to characterize the recrystallization kinetics. The micrographs of the steel were obtained using optical microscopy (OM) to characterize the grain
microstructure of
the non-treated and the annealed steel samples. Annihilation of dislocation defects
occur within the soaking time of 5 - 10 minutes for all
the deformed steel after annealing at 650°C. Specifically at 5 minutes soaking
time the grains elongation is still observed indicating that reformation of
grains is not taking place but recovery of the deformed grains. At the 10
minutes annealing time, new grains are observed to begin and full recrystallization is achieved
at 15 minutes annealing time. At annealing time between 20 - 25 minutes, grains coarsening are
observed indicating the onset of grain growth. The hardness of the material reduces with increasing
annealing temperature for all the degree of cold drawn deformation. On the
basis of the experimentally obtained hardness values, recrystallization
increases with increasing degree of cold drawn deformation for the annealed
steel. Recovery process was found to prolong in the 20% cold drawn steel as
compared to the 55% cold drawn steel. The prolong recovery process is due to
reduction in the driving force. Full recrystallization of the annealed steel is achieved at different
soaking time depending on the degree of the cold drawn steel.