SUMMARY

Hydrogen embrittlement is a long-standing issue in material science and engineering with a multitude of competing hypotheses and theories. Despite advances in experimental and computational capabilities, common understanding of contributing phenomena has not yet been achieved. Hence, a more complete understanding of hydrogen embrittlement processes operating at multiple length and time scales is still an open challenge that justifies the proposed research. In this work, a unique approach is proposed to incorporate a wide range of experimental, computational, and analytical approaches across multiple length scales to produce a mechanistically motivated hydrogen embrittlement model for fracture and fatigue. The proposed research will attempt to describe and simulate the complex interplay between hydrogen, hydrogen-related defects, dislocations, and dislocation substructures. The model will be developed in a crystal plasticity (CP) context and implemented in a finite element framework (FEM) to simulate the hydrogen embrittlement of face-centered cubic (FCC) AISI 316L stainless steel (SS316L), a structural material important in energy applications. The proposed research will extend current understanding with three main contributions, including development and implementation of:
i. a hydrogen transport and trapping model that considers dislocation-mediated transport mechanisms and a more complete set of hydrogen traps,
ii. a model that considers evolution of internal point and line defects, including interactions with hydrogen, and
iii. a damage accumulation model to capture the effects of hydrogen in reducing crack tip ductility, leading to embrittlement effects.