Enhancing hydrogen embrittlement resistance in Fe-30Mn-xAl-3Si twinning-induced plasticity (TWIP) steels by modulating phase transformation and deformation mechanisms

Hydrogen embrittlement is a critical challenge for steels exposed to a hydrogen-containing environment. In this work, the Fe-30Mn-xAl-3Si twinning-induced plasticity (TWIP) steels with different Al content were employed to study the effect of phases and deformation mechanisms on hydrogen embrittlement resistance. The results show that increasing Al content induces a transition from a single γ-Fe phase to a dual γ-Fe/α-Fe microstructure, accompanied by reduced γ-Fe fraction and twinning ability. Mechanical testing reveals that higher Al significantly intensifies hydrogen-induced degradation. Surface crack analysis and fracture morphologies further confirm that steels with low and moderate Al contents exhibit limited hydrogen embrittlement susceptibility, whereas high-Al TWIP steel develops elongated, widened cracks and shallow dimples indicative of severe embrittlement. Microstructural evaluation shows that γ-Fe and deformation twins improve hydrogen embrittlement resistance by reducing hydrogen mobility, while α-Fe formation and dislocation-dominated deformation promote irreversible hydrogen trapping and crack initiation. Overall, Al addition governs phase evolution, deformation behavior, and hydrogen embrittlement resistance in Fe-30Mn-xAl-3Si TWIP steels. These findings clarify how Al-driven phases and deformation mechanisms tailoring governs hydrogen embrittlement resistance in TWIP steels, providing a foundation for designing next-generation high-strength, hydrogen-tolerant alloys for safer structural and energy applications.