Hydrogen embrittlement (HE) is a well-known phenomenon that deteriorates the mechanical properties of several metallic materials. Generally, HE susceptibility rises with increasing strength of the material. However, its effect on ductility is worse than on strength. The effects associated with hydrogen embrittlement in metals can lead to catastrophic failures. Nickel martensitic stainless steels (Ni-MSS) are based on the Fe-Cr-Ni-Mo system with low amounts of interstitial atoms, especially C. Due to the good combination of strength considerably higher than austenitic stainless steels (ASS), toughness and corrosion resistance, Ni-MSS are used in applications like oil and gas, aerospace and power generation. In contrast to low strength ASS, there is little research on the influence of hydrogen on mechanical properties of Ni-MSS.

The aim of this work was to study the susceptibility to hydrogen embrittlement of different Ni-MSS, like UNS S17400, S41426 and 1.4418. Thus, slow strain rate tests were conducted after cathodic charging. Additionally, the hydrogen content was measured in uncharged and charged condition aiming to correlate hydrogen content introduced by charging time and hydrogen embrittlement susceptibility. Hydrogen embrittlement of Ni-MSS depends on charging time and hydrogen content. HE has a higher effect on ductility than on strength. It rises with increasing mechanical strength. The microstructure, such as retained austenite and precipitates, also has an influence on the HE susceptibility.