Statistical study on the effects of heterogeneous deformation and grain boundary character on hydrogen-induced crack initiation and propagation in twining-induced plasticity steels

The initiation and propagation of hydrogen-induced cracks (HICs) in twining-induced plasticity (TWIP) steel were quantificationally explored based on the HIC statistics at a macro level and a micro level by slow strain rate tensile (SSRT) with in-situ hydrogen-charging and electron microanalysis. The heterogeneous deformation and grain boundary character determines a HIC initiation. The slip transfer parameter m′ < 0.93 and the minimum residual Burgers vector of residual dislocations on a grain boundary br > 0.19 were the critical condition for HIC initiation. Moreover, HICs prone to initiate and propagate along random grain boundaries (RGBs), while the Σ3 grain boundaries and vice.