Different augmentations of absorbed hydrogen under elastic straining in high-pressure gaseous hydrogen environment by as-quenched and as-tempered martensitic steels: combined experimental and simulation study

Hydrogen embrittlement (HE) behavior of as-quenched and as-tempered martensitic steels under elastic straining in a high-pressure gaseous hydrogen environment was studied for the first time. The difference in the total content of defects acting as H trap sites has the highest contribution to the increase in absorbed hydrogen content under the elastic loading. The hydrogen-induced fracture occurred in the as-quenched specimen during elastic straining in hydrogen environment, while the tempered specimen did not fracture under the elastic loading. Higher accumulation of the dislocations near the main crack initiation sites (prior austenite grain boundaries (PAGBs)) in the as-quenched specimen will be the main source of the hydrogen to the potential flaw to crack to initiate. H accumulated near PAGBs enhances dislocation slip along {011} planes and helps transgranular crack propagation. Due to less possibility to provide the critical local amount of hydrogen at PAGBs for the crack to initiate, the as-tempered specimen remained unfractured.