Synergistic hydrogen embrittlement in high-strength steels

Area of Science:

• Materials Science
• Metallurgy
• Hydrogen Embrittlement

Background:

• Hydrogen embrittlement (HE) is a major obstacle for the hydrogen economy.
• Predictive models for HE are limited by incomplete understanding of hydrogen's effect on deformation, especially in complex alloys.
• High-strength martensitic steels are crucial for infrastructure but susceptible to HE.

Purpose of the Study:

• To investigate the synergistic hydrogen embrittlement (SHE) phenomenon in high-strength martensitic steels.
• To elucidate the role of carbon in hydrogen-induced material failure.
• To develop insights for designing hydrogen-tolerant materials.

Main Methods:

• Microcantilever bending tests to assess hydrogen susceptibility and deformation behavior.
• First-principles calculations to model hydrogen-dislocation interactions.
• Theoretical modeling to understand hydrogen redistribution mechanisms.

Main Results:

• A synergistic hydrogen embrittlement (SHE) phenomenon was demonstrated, where hydrogen and carbon interact to enhance localized plasticity (HELP).
• Increased carbon content in martensitic steels led to greater hydrogen susceptibility, reduced work-hardening capacity, and decreased ductility.
• Modeling revealed carbon intensifies hydrogen-dislocation interactions and inhibits cross-slip by amplifying hydrogen redistribution around screw dislocations.

Conclusions:

• Carbon significantly exacerbates hydrogen embrittlement in high-strength steels through synergistic interactions.
• Understanding these synergistic effects is critical for predicting and mitigating hydrogen-induced failures.
• This research provides foundational knowledge for designing robust, hydrogen-tolerant structural materials for a carbon-free future.