Effect of grain boundary character distribution on hydrogen embrittlement in Fe–Ni based alloy

The feasibility of using grain boundary engineering (GBE) to reduce the susceptibility of hydrogen embrittlement in precipitation strengthened Fe–Ni based austenitic alloy is investigated. After GBE treatment, the fraction of special boundaries (SBs) increased from 46% to 78% while the hydrogen-induced loss of elongation is decreased from 21.8% to 8.6%. This improvement of hydrogen resistance can be attributed to not only the high fraction of SBs but also the disruption of random grain boundaries (RGBs) network. As the former has high resistance to hydrogen-induced crack initiation and the later can suppress the propagation of cracks.