The effects of hydrogen on the physical and mechanical properties of iron and steel are reviewed. A new mechanism for the cold work peak for hydrogen in iron is considered. Together, internal friction and mechanical properties indicate that hydrogen softens iron by enhancing screw dislocation mobility at room temperature but hardens iron by core interactions at low temperatures. No single mechanism exists for the degradation of the properties of steel by hydrogen. Instead a complex process involving many of the proposed mechanisms as contributing factors is shown to account for most degradation phenomena.

Effects of hydrogen on the properties of iron and steel

The mechanisms of hydrogen-related fracture are briefly reviewed and a few evaluative statements are made about the stress-induced hydride formation, decohesion, and hydrogen-enhanced localized plasticity mechanisms. A more complete discussion of the failure mechanism based on hydrogen-enhanced dislocation mobility is presented, and these observations are related to measurements of the macroscopic flow stress. The effects of hydrogen-induced slip localization on the measured flow stress is discussed. A theory of hydrogen shielding of the interaction of dislocations with elastic stress centres is outlined. It is shown that this shielding effect can account for the observed hydrogen-enhanced dislocation mobility.

Hydrogen-enhanced localized plasticity—a mechanism for hydrogen-related fracture

Hydrogen embrittlement of α titanium: In situ tem studies

S. Gahr

Papers

Hydrogen embrittlement of Nb I—Macroscopic behavior at low temperatures☆

Hydrogen embrittlement of niobium—III. High temperature behavior☆

Fracture of niobium hydride