Elucidating the dynamics of hydrogen embrittlement in duplex stainless steel

We used slow-strain rate testing with in-situ microstructure imaging during electrochemical hydrogen charging to understand hydrogen embrittlement of super duplex stainless steel. Tensile deformation during hydrogen absorption softens the austenite and ferrite phases, lowering the macroscopic yield point and fracture strain. In contrast, when hydrogen absorption precedes micro-tensile testing, it strengthens the microstructure, highlighting a complex dual response. Computational analyses showed hydrogen atoms are trapped at phase boundaries, increasing the ferrite phase's hardness but reducing the austenite phase's hardness. However, once the boundaries are passivated, further entering hydrogen can diffuse rapidly without energy barriers, resulting in softening of both phases.