| Abstract Scope |
High-Mn steel is subjected to hot deformation and grain boundary engineering (GBE) type processing to investigate the mechanisms behind distribution of grain boundary characters. In hot deformation processing, steel is subjected to 50% deformation at strain rates of 0.01-10 s-1 and within the temperature range of 1073-1373 K. In GBE type processing, steel is subjected to small amount of cold deformation (5% and 15%), followed by annealing at higher temperature (1173 K) for varying period (0.5-10 hours). This study unveils the relative roles of recrystallization, grain growth, and strain induced boundary migration (SIBM) in the development of GBE microstructure. Quantification of GBE microstructure involves the use of ∑3n fractions, twin related domain (TRD) parameters, triple junction fraction, and fractal dimension. The findings indicate that the GBE microstructure does not result from the occurrence of either static recrystallization (SRX), dynamic recrystallization (DRX), or grain growth. Instead, GBE microstructure is achieved through multiple twinning activated by SIBM. The activation of SIBM leads to higher fraction of ∑3n boundaries. Consequently, an increase in the triple junction (J2 and J3) distributions and the number of grains per TRD is achieved. However, either of DRX, SRX or grain growth results in smaller TRD sizes, lesser number of grains per TRD, and continuous network of random high angle boundary. This clearly suggests that SIBM, rather than recrystallization/grain growth, is responsible for the greater extent of ∑3n boundary evolution during GBE processing. |