The paper of Prof.Petros Sofronis (Direcor, Principal Investigator,HydrogenMaterialsCompatibility Research Division, I²CNER), Dr.Shuai Wang (Hydrogen Materials Compatibility Research Division,I²CNER), and their collaborative research group was published in “Acta MATERIALIA” on Mar. 14, 2014.
The hydrogen embrittlement of a commercial-grade pure iron was examined by using repeated stress-relaxation tests under simultaneous cathodic hydrogen charging. The hydrogen-charged iron, containing an estimated 25.8 appm H, fractured after repeated transients, with a total strain of ∼5%. The fracture mode was intergranular. Thermal activation measurements show a decrease in activation volume and free energy, which is consistent with hydrogen enhancing the dislocation velocity. The microstructure beneath the intergranular facets displays a dislocation cell structure more complex than expected for intergranular fracture and this strain-to-failure. It is proposed that hydrogen accelerates the evolution of the dislocation microstructure through the hydrogen-enhanced plasticity mechanism and this work-hardening of the matrix along with the attendant hydrogen concentration at the grain boundaries are crucial steps in causing the observed hydrogen-induced intergranular failure.
* Authors: Shuai Wang, May L. Martin, Petros Sofronis, Somei Ohnuki, Naoyuki Hashimoto,
Ian M. Robertson
* Article first published online: 14 Mar, 2014