| Abstract Scope |
Austenitic manganese steels exhibit exceptional strain hardening through deformation twinning. However, there is limited understanding of the effects of twinning on the fracture response of these materials. This work combines in-situ tensile experiments on single-crystal dog-bone and single-edge notched specimens with finite element simulations using a rate-dependent crystal plasticity model incorporating slip and twinning. The specimens were oriented to favor either twinning or crystallographic slip, enabling isolation of deformation-mode effects. Our findings reveal that in notched single-crystal specimens oriented to preferentially activate deformation twinning, twinning causes asymmetric notch deformation and promotes crack nucleation and growth along twin boundaries. As twins grow thicker through new twin formation, widening, and coalescence, the crack undergoes non-smooth blunting and arrest, followed by secondary crack nucleation. This repeating process significantly enhances fracture resistance. In contrast, specimens oriented to preferentially activate crystallographic slip deform symmetrically, with cracks maintaining a relatively sharp crack tip throughout fracture. |