Orientation Dependence on Plastic Flow Behavior of Hydrogen-Precharged Micropillars of High-Mn Steel

This study investigated the dependence of grain orientation on the hydrogen embrittlement (HE) characteristics of high-Mn twinning-induced plasticity steels. Single-crystal micropillars were fabricated to represent the five major texture components of face-centered cubic structure: brass, Goss, copper, cube, and S components. These were classified into three groups for discussion based on the microstructural and mechanical characteristics. The copper and cube micropillars showed the lowest HE resistance because of an exclusive formation of twin boundaries that led to a localized hydrogen concentration. Brass and Goss micropillars revealed multiple slips with increasing strain, which was different from the case of S orientation that exhibited the activation of single slip system. The results of this work suggest that increasing frequency of S component grains would enhance HE resistance owing to the inhibited twinning and suppressed dislocation mobility. This is supported by the superiority of S/cube bicrystal micropillar to Goss/cube micropillar in terms of HE resistance. Graphic