R. Chai, G. Álvarez, , C. Wu, J. Parker, M. Gagliano, L. Cupertino-Malheiros
International Journal of Hydrogen Energy
https://doi.org/10.1016/J.IJHYDENE.2026.157075
Resumen
Our work advances understanding of hydrogen distribution within the heterogeneous microstructures of girth welds. A new methodology is used for vintage and modern X60 pipeline steels, combining: (i) isothermal desorption at room temperature, (ii) desorption at a constant heating rate up to 1000 (Formula presented), and (iii) fitting desorption data using Fick’s law and multi-trapping models. The results show that large amounts of residual trapped hydrogen are present before hydrogen charging, with the weld metals containing the highest concentrations up to 8 wppm. The desorption spectra show three strong trapping sites with binding energies of approximately 65, 100, and 140 kJ/mol. In contrast, diffusible hydrogen was introduced during electrochemical charging, with higher concentrations in the vintage steel. Isothermal desorption and permeation show a similar dependence of diffusivity on trapping, with comparable diffusion coefficients for both steels, except for the significantly slower diffusion in the hard heat-affected zone of the vintage steel.