Production of nanograin microstructure in steel nanocomposite

In this study, microstructure and mechanical properties of steel/2 vol% SiC nanocomposite fabricated via accumulative roll bonding (ARB) process were investigated. Microstructure of nanocomposites was studied by scanning transmission electron microscopy (TEM). Tensile test also applied for determination of properties. In addition, the dislocation density was estimated from hardness measurement. The results indicated that continuously dynamic recrystallization (CDRX) and discontinuously dynamic recrystallization (DDRX) occurred in the microstructure of steel-based nanocomposite and the nanograins (55 nm) were obtained after the final cycle. With increasing the number of ARB cycles, the dislocation density of nanocomposite increased. In addition, after the first cycle, a significant increase observed in the yield strength, from 84 MPa to 689 MPa which is almost 8.2 times greater than that of the initial sample. After final cycle, the yield strength value increased to 1189 MPa. The yield strength improvement was mostly due to the grain refinement and dislocations and to a lesser extent to the load bearing effects of second phase (SiC nanoparticles) and precipitates. The contribution of each of these mechanisms was evaluated.