Effect of deformation and annealing temperatures on ultrafine microstructure development and yield strength of pearlitic steel through continuous recrystallization

Associated with the durability of railway wheels, microstructure development of high-carbon steel (0.67% C) during uniaxial compressive deformation and after subsequent annealing was studied using scanning electron microscopy and electron back scattering diffraction. The spheroidization of cementite is accelerated due to compressive deformation depending on the temperature. Annealing at 600 deg. C leads to the formation of ferrite grain boundaries due to continuous recrystallization and results in an ultrafine microstructure with a ferrite grain size of less than 1 μm. Formation of high angle boundaries due to the dislocation accumulation on low angle boundaries results in an equiaxial fine microstructure after deformation at 700 deg. C. Annealing at 600 deg. C or higher leads to the coarsening of spheroidized cementite, which reduces the pinning effect of the particles to the migration of high angle boundaries. The compressive yield stress increased approximately 25% through microstructure development, along with a decrease in the work hardening rate.