Effects of Hot Deformation on the Evolution of Microstructure in Pearlitic Steel Wire Rod

The influences of hot deformation parameters on pearlite grain nucleation and growth during austenite-pearlite phase transformation in a steel wire rod have been investigated through quantitative analysis of microstructure parameters such as austenite grain size, ferrite grain size, pearlite colony size, and lamellar spacing. During hot deformation, the austenite grain size decreases due to recrystallization, providing extra nucleation sites for pearlite phase transformation, which decreases the ferrite grain size and pearlite colony size. Moreover, the stored strain energy in undercooled austenite accelerates carbon diffusion during pearlite phase transformation, which facilitates ferrite grain growth and increases pearlite colony size. Consequently, the competing influence of recrystallization and strain energy provides flexibility in adjusting ferrite grain size and colony size by hot deformation. This study highlights the critical role of hot deformation in determining the microstructure of pearlitic steel.