Hydrogen trapping on lattice defects produced by high-pressure torsion in Fe–0.01 mass% C alloy

Hydrogen trapping in Fe–0.01 mass% C with ultrafine-grained structures produced by high-pressure torsion (HPT) was investigated by thermal desorption spectrometry. Hydrogen trapping in body-centred cubic iron was significantly increased by HPT processing through introduction of lattice defects such as vacancies, dislocations and grain boundaries. Decreasing the density of vacancies, dislocations and low-angle grain boundaries by post-HPT annealing is effective in reducing the trapped hydrogen while the hardness remains enhanced through grain refinement with high-angle boundaries.