Identification of Hydrogen Trapping Sites Binding Energies and Occupation Ratios at Vacancies Dislocations and Grain Boundaries in Iron of Varying Carbon Content

摘要

To reduce the susceptibility of metals to hydrogen embrittlement, it is important to identify hydrogen trapping sites, binding energies, and occupation ratios at various lattice defects. A thermal desorption spectrometer heated from lower temperature, which we have developed, facilitates analyses of these aspects. In the present study, the influence of carbon and carbide on peak temperatures of hydrogen desorption, binding energies and occupation ratios in iron was examined. The iron specimens contained 6 ppm, 0.005%, 0.01% and 0.1% carbon. In the case of dislocation trapping, a peak temperature at 10℃ desorbed from dislocations decreased with increasing carbon content. The binding energy between dislocations and hydrogen decreased with increasing carbon content from 24.9 to 17.7 kJ/mol. The hydrogen occupation ratio at dislocations also decreased with increasing carbon content. These findings indicate that carbon has a significant influence on hydrogen trapping behavior in iron, since it and other interstitial atoms occupy lattice defects instead of hydrogen.