The Recrystallization Nucleation Mechanism for a Low-Level Strained 316L Stainless Steel and Its Implication to Twin-Induced Grain Boundary Engineering

The thermal-mechanical processing (TMP) for twin-induced grain boundary engineering (GBE) generally adopts a small amount of cold deformation and subsequent annealing at solution temperature of austenitic stainless steels. The nucleation mechanism during the TMP of GBE is essential to the understanding of the evolution of grain boundary character distribution (GBCD). The mechanism for recrystallization nucleation is investigated in a 316L austenitic stainless steel which was subjected to short-time annealing at solution-annealing temperature after 5–10 pct tensile deformation. A total of 22 recrystallization nuclei were found, and the analyzing of the orientation relationships between the nuclei and nearby deformed grains revealed that most of the nuclei are formed following the strain-induced boundary migration (SIBM) mechanism. The formation of highly twinned grain-clusters as the typical feature of GBE microstructure is a result of extensive multiple twinning starting from every single nucleus. Low nucleation density is more important than how the nucleus forms during GBE. A portion of the recrystallization front boundaries outside the clusters expanded into the deformation microstructure more extensively than the others. However, the growth advantage does not have an obvious correlation with the misorientation of these recrystallization front boundaries.