Theses and Dissertations

Issuing Body

Mississippi State University


Rhee, Hongjoo

Committee Member

Doude, Haley

Committee Member

Doherty, Kevin

Committee Member

Whittington, Wilburn

Date of Degree


Document Type

Dissertation - Open Access


Mechanical Engineering

Degree Name

Doctor of Philosophy (Ph.D)


James Worth Bagley College of Engineering


Department of Mechanical Engineering


High hardness steels (HHS) are vulnerable to hydrogen embrittlement, which can lead to rapid degradation of mechanical properties. Improved resistance to hydrogen embrittlement would be beneficial to many industries including construction, automotive, and military. A comparison study was performed to assess the hydrogen susceptibility of select commercially available and in-house designed HHS alloys. Slow strain rate tensile tests, performed with specimens charged with various levels of hydrogen, provided a macroscopic view of the onset of hydrogen embrittlement. Hydrogen permeation and thermal desorption spectroscopy tests determined the uptake and diffusivity of hydrogen through the material. The evaluation of hydrogen susceptibility for various HHS alloys provided a baseline for the design of an HHS alloy containing hydrogen embrittlement mitigation strategies. By incorporating strong hydrogen traps, titanium carbide and epsilon carbide, a HHS was produced that demonstrated a lower sensitivity to hydrogen embrittlement