The mechanism of mechanical twinning near grain boundaries in twinning-induced plasticity steel

The mechanism of mechanical twinning in the vicinity of a grain boundary, which has been considered as a twin nucleation site, was investigated using Fe-17.5Mn-0.58C-1.5Al twinning-induced plasticity steel. When tensile strain was 0.02, multiple slips occurred near grain boundaries. The interaction between dislocations on multiple slip planes resulted in stacking faults composed of Shockley and Frank partial dislocations at the locations slightly away from grain boundaries. When the strain reached 0.05, mechanical twins formed near grain boundaries to grow toward the interior of grains. This observation result matched well with twinning mechanism proposed by Miura, Takamura, and Narita.