Effect of Particles on Continuous and Discontinuous Recrystallization of Nanostructured Interstitial Free Steel

Abstract

In this study, the effect of micro- and nano- particles on continuous and discontinuous dynamic recrystallization (DDRX) of nanostructured interstitial free (IF) steel was investigated. Microstructural observations were performed by scanning transmission electron microscopy. It was found that minimum and maximum final grain size obtained for nanocomposite and pure steel was 55 nm and 95 nm, respectively, while the final grain size of composite was 73 nm. Also, after the final cycle, the microstructure of the pure steel and the nanocomposite was homogeneous while that of the composite was relatively inhomogeneous. One of the most interesting observations in the present work was that the IF steel with high stacking fault energy (200 mJ/m2) could discontinuously recrystallize to form new grains during the accumulative roll bonding (ARB) process at room temperature. Due to the temperature increase during the ARB process, nuclei formed in the area around the silicon carbide particles and at grain boundaries. The presence of silicon carbide particles in the IF steel matrix retarded recovery and led to the retaining of the high stored energy of the ARB process in the material and therefore, there was a greater driving force for DDRX.