Research Projects
Hydrogen Embrittlement Group

Hydrogen embrittlement (HE) is one of the most dangerous embrittlement problems in metallic materials and  advanced high-strength steels (AHSS) are particularly prone to HE with the presence of only a few parts-per-million of H. However, the HE mechanisms in these materials remain elusive, especially for the lightweight steels where the composition and microstructure significantly differ from the traditional plain-carbon steels. Here we focus on a high-Mn and high-Al lightweight steel and unravel the effects of H-associated decohesion and localized plasticity on its H-induced catastrophic failure.

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About 90% of all mechanical service failures are caused by fatigue. Avoiding fatigue failure requires addressing the wide knowledge gap regarding the micromechanical processes governing damage under cyclic loading, which may be fundamentally different from that under static loading. This is particularly true for deformation-induced martensitic transformation (DIMT), one of the most common strengthening mechanisms for alloys. Here, we identify two antagonistic mechanisms mediated by martensitic transformation during the fatigue process through in situ observations and demonstrate the dual role of DIMT in fatigue crack growth and its strong crack-size dependence. Our findings open up avenues for designing fatigue-resistant alloys through optimal use of DIMT. They also enable the development of physically based lifetime prediction models with higher fidelity.
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In this project we study the degradation of hydrogen embrittlement resistivity of austenitic high-Mn and high-Al lightweight steels upon age hardening and discover ways to mitigate this deterioration. more

The main aspect of this project is to understand how hydrogen interacts with dislocations/ stacking faults at the stress concentrated crack tip. A three-point bending test has been employed for this work. more