Direct observation of hydrogen-trapping sites in vanadium carbide precipitation steel by atom probe tomography

Atomic-scale direct observation of hydrogen-trapping sites in vanadium carbide (VC) precipitation steel was performed using a three-dimensional atom probe (3DAP) with a deuterium-charging method. Most of the deuterium (D) atoms were observed at larger VC platelets, while such trapping of D atoms was not observed at smaller VC platelets. 3DAP analysis showed that these platelets had the chemical composition V4C3. The results suggest that the misfit dislocation cores on semicoherent platelets are deep trapping sites for hydrogen.