Effect of Cold Deformation on the Hydrogen Permeation Behavior of X65 Pipeline Steel

In this study, an electrochemical hydrogen permeation experiment was used to determine the diffusion parameters, and a hydrogen microprint test was used to visualize the distribution of hydrogen in X65 pipeline steel with different levels of cold deformation. The hydrogen permeation curves show that both hydrogen permeation current density and effective hydrogen diffusion coefficient decrease with increasing cold deformation. The density of reversible and irreversible hydrogen traps is calculated from the permeation parameters, and it is found that the amount of both traps increases with increasing deformation, especially a significant increase in reversible hydrogen traps, which is in agreement with the results measured by thermal desorption spectroscopy. Hydrogen microprint test results indicate that the degree of hydrogen aggregation on the specimen surface increases with increasing cold deformation, especially at phase and grain boundaries. In addition, the dislocation configuration after cold deformation was further investigated by transmission electron microscopy.

Automated summary

In this study, electrochemical hydrogen permeation experiment and hydrogen microprint test were used to investigate the diffusion parameters and distribution of hydrogen in X65 pipeline steel with different levels of cold deformation. The results showed that the hydrogen permeation current density and effective hydrogen diffusion coefficient decreased with increasing cold deformation. The density of both reversible and irreversible hydrogen traps increased with deformation, especially reversible hydrogen traps. The hydrogen microprint test revealed increased hydrogen aggregation on the specimen surface, especially at phase and grain boundaries. Transmission electron microscopy was also used to examine the dislocation configuration after cold deformation.