Evaluating hydrogen susceptibility in pipeline steels: A screening approach based on microstructural and hydrogen characteristics correlations
Published in International Journal of Hydrogen Energy, 2026
Keywords: Hydrogen embrittlement (HE); Pipeline steels; Tensile testing; Hydrogen–microstructure interactions; Statistical screening tool
Abstract
This study develops a screening methodology aimed at ranking the parameters that govern the hydrogen embrittlement (HE) sensitivity of repurposed pipeline steels. Five pipeline steels (X56, X60 and X70) were characterised using light and electron microscopy, X-ray diffraction, and positron annihilation spectroscopy. Electrochemical hydrogen charging was performed. Hydrogen uptake capacity was determined via hot extraction at 950 °C, while trapping characteristics were evaluated via thermal desorption spectroscopy at different heating rates. The apparent hydrogen diffusion coefficient was determined by electrochemical permeation. Mechanical characterisation included tensile tests on both smooth and notched round bar specimens to quantify HE indices. A database of descriptors was established, including ferrite grain size, pearlite fraction, grain boundary density, dislocation density, open-volume defects, hardness, carbon equivalent, hydrogen uptake, and embrittlement indices. Thermal desorption spectra exhibited only peaks below 200 °C indicating reversible traps such as dislocations, vacancies, grain boundaries and interfaces that dominated hydrogen uptake across all materials. Spearman correlation analysis indicated that hydrogen uptake capacity controls HE sensitivity, which is governed by the total amount of open-volume defects. The range of hardness values (190–220 HV10) of the tested materials was not extensive enough to make statements on the reliability of using hardness values to predict HE sensitivity.
Recommended citation: Jubica, L. Claeys, A. Laureys, L. De Pue, W. De Waele, J. Schweicher, K. Verbeken, T. Depover, "Evaluating hydrogen susceptibility in pipeline steels: A screening approach based on microstructural and hydrogen characteristics correlations," International Journal of Hydrogen Energy 250 (2026) 155998. doi:10.1016/j.ijhydene.2026.155998
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