Understanding Hydrogen Embrittlement in Steels from Atomistic Perspective

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To achieve net-zero emission by 2050 and position Canada as a global leader of clean renewable fuels, hydrogen plays a vital role. `Hydrogen Strategy for Canada' visions the hydrogen as opportunities to make Canada as a world leading supplier of hydrogen technologies, and to help Canada to stimulate economic recovery, provide plenty of high-paying jobs, and reach net-zero emissions by 2050. One of the major technical considerations identified in the `Strategy' is hydrogen embrittlement (HE), which is associated with serious materials deterioration during hydrogen storage and transportation. Hydrogen embrittlement is a well-documented phenomenon involved degradation in mechanical properties of the materials, such as loss in ductility, strength, and toughness due to the presence of diffusive hydrogen atoms. HE was first reported in late nineteenth century, and the component failures because of HE has been observed in almost all engineering metallic materials. Although a large amount of researches with different advanced experimental techniques and computational simulations has been conducted in the last hundred years, especially in the last four decades, the underlying mechanisms for HE is still not completely understood. Many mechanisms have been proposed in the past to explain HE, however, none of them can explain HE in all different conditions, which leads to a conclusion that in some scenario one of the mechanisms could become a governing mechanism, while in some other scenario multiple mechanisms could synergistically interplay. In the current research, we propose to investigate the synergistic interplay between different major HE mechanisms, namely, one associated with hardening effect and the other related to softening effect. In particular, we will employ molecular dynamics (MD) and density function theory (DFT) to investigate the interaction between diffusive/trapped hydrogen and crystal defects to systematically study the effects of hydrogen transport on the mechanical response in steels under static/dynamic loading conditions. In addition, scenarios of hydrogen transport in the presence of a `network' of defects under different loading conditions will be created to clarify the synergistic interplay between different HE mechanisms. We believe the success of this proposed research will improve our current understanding of HE at the atomistic level, and provide possible solution to minimize HE in hydrogen storage and transportation, which is essential to position Canada as a leader in hydrogen technologies.