S. Otero, S. Sampayo, G. Álvarez, F.J. Belzunce, C. Rodríguez
Theoretical and Applied Fracture Mechanics
https://doi.org/10.1016/j.tafmec.2026.105661
Resumen
Hydrogen is a key enabler for low-carbon energy systems but its interaction with structural steels remains a major challenge due to hydrogen embrittlement (HE). In this work, in-situ electrochemical Small Punch Tests, SPTs, are used to quantify hydrogen-assisted degradation in 17 steels, comprising five microstructural families (austenitic, ferritic, ferritic-pearlitic, duplex and tempered martensitic steels). Tests were conducted at a constant current density and punch displacement rate using two hydrogen charging media with different hydrogen entry efficiencies: an acidic electrolyte and a saline electrolyte. Susceptibility to hydrogen was quantified using the hydrogen embrittlement index (HEI) derived from dm/t0, εqf and Wm/t02, which provide the most consistent discrimination between microstructures. Microstructure plays a crucial role in the hydrogen-assisted response: tempered martensitic steels were the most susceptible, ferritic-pearlitic and duplex steels exhibited intermediate behaviour, and austenitic stainless steels had the lowest susceptibility. The HEI values increased with the steel yield strength. The differences between steels charged in the acidic and saline media were generally minimal and the saline electrolyte was able to rank the steels while simplifying laboratory handling. These results demonstrate that in-situ electrochemical hydrogen-charging SPTs provide a robust approach for HE screening, particularly suited to cases with limited material, such as welded joints and service-exposed components.