Evidencing extrinsic stacking faults in twinning-induced plasticity steel

In twinning induced plasticity (TWIP) steel, the question of what leads to the onset of twinning in grains whose (100) orientations are near parallel to the tensile axis at high tensile strains has not been resolved. Using aberration corrected scanning transmission microscopy we present first-hand evidence that extrinsic stacking faults serve as nuclei for twins in (100) grains and also contribute to twin growth in a low carbon TWIP steel uniaxially tensile loaded up to its ultimate tensile strength of ~ 1080 MPa; which corresponds to a tensile true strain of 48%. The results corroborate and validate our previous Schmid factor¿based predictions on the feasibility of twinning nucleation via extrinsic stacking faults in (100) grains at high tensile strains.