Effects of plastic deformation on hydrogen trapping and hydrogen distribution in X80 pipeline steel

The characteristics of hydrogen trapping and hydrogen distribution for the unstrained and strained X80 pipeline steel were investigated in this work. Ultra-high vacuum thermal hydrogen desorption spectroscopy tests were conducted on the hydrogen pre-charged specimens to study the properties of hydrogen trapping under the influence of plasticity. Results showed that the binding energy of the dislocation trap generated by plastic deformation was 28.30∼33.84 kJ/mol, increasing with the increase of strain. As the deformation in the material increased, the number of dislocation traps as well as the hydrogen trapped in the dislocations increased, leading to a higher hydrogen content in the strained specimens. Additionally, finite element simulations were employed to elucidate the properties of hydrogen distribution as affected by plasticity. The binding energy of dislocation trap had a significant effect on the calculated maximum hydrogen concentration in the specimen. Hydrogen trapped at the dislocations during the plastic deformation stage dominated the maximum total hydrogen concentration in X80, which was consistently in the region of greatest strain and increased with the increasing strain and binding energy of hydrogen trapping.