Hydrogen embrittlement (HE) of ferritic and martensitic steels is a long-standing and widely recognized phenomenon that presents a significant challenge to numerous technical applications. Its versatile nature depends on environmental conditions as well as on microstructural features, often leading to a premature material failure. A variety of different hydrogen embrittlement failure mechanisms have been proposed, commonly divided in plasticity-mediated and decohesion-related ones.

In the present study, a model approach is employed, utilizing proposed failure mechanisms, to investigate the fatigue performance of ferritic steel in hydrogen environments. Considering that metal components are typically subjected to cyclic mechanical loading, addressing the impact of hydrogen on fatigue behavior is becoming increasingly relevant and of great interest.

One of the main factors that determine the fatigue behavior of a metal and thus the lifetime of a component is attributed to the multi-crystalline microstructure of the metal. A well-established approach to describe microstructural influences on the mechanical behavior of metals is the crystal plasticity (CP) theory [1]. Due to their capability of a microstructure-sensitive modeling, CP-FEMs are useful to examine damage caused by fatigue in the material.

Here, a diffusion-coupled CP-FEM simulation approach is used to study the impact of environmental conditions and internal hydrogen concentrations on fatigue crack initiation. The influence of variable temperatures and hydrogen gas pressures with regard to the prediction of fatigue damage is discussed and investigated.

[1] F. Roters et al. Acta mater 58.4 (2010): 1152-1211