M.M. Llera, G. Álvarez, F.J. Belzunce, C. Rodríguez
Engineering Failure Analysis
https://doi.org/10.1016/J.ENGFAILANAL.2026.111355
Resumen
Base metal and weld metal from a S420 steel welded joint were characterised in air and under in-situ electrochemical hydrogen charging. Charging was performed in a 3.5wt.%NaCl solution at 2 mA/cm2, selected to provide conservative approximation of hydrogen uptake during exposure to 80 bar H2. Tensile properties, fracture toughness and fatigue crack growth behaviour were determined for both regions. Hydrogen uptake had no significant effect on yield strength or tensile strength, but markedly reduced ductility. Fracture toughness decreased severely, with an average hydrogen embrittlement index around 80%, while fatigue crack growth rates increased by approximately one order of magnitude. Both materials exhibited similar tensile and fatigue crack growth behaviour. However, under hydrogen, the weld metal retained higher apparent fracture toughness than base metal, attributed to its refined ferritic/acicular ferritic microstructure. Overall, the results support in-situ electrochemical hydrogen charging as cost-effective and conservative approach for assessing hydrogen-assisted degradation in S420 steel welded joints.