V. Arniella, G. Álvarez, F.J. Belzunce, C. Rodríguez
Engineering Fracture Mechanics
https://doi.org/10.1016/J.ENGFRACMECH.2025.111419
Resumen
The effect of in-situ electrochemical hydrogen charging on the fracture toughness of 42CrMo4 steel was evaluated, with a particular focus on comparing hydrogen content achieved by gaseous and electrochemical charging methods. Hydrogen absorption was quantified after gaseous charging, and after electrochemical charging using two kind of electrolytes (acid and saline) and various current densities. Correlations between the hydrogen contents and the applied current density have been defined for each kind of electrolyte. A current density of 0.2 mA/cm2 using the saline electrolyte would introduce the same amount of hydrogen as a realistic but demanding service condition operating at 1000 bars. Regardless of the type of electrolyte used, the toughness of the material decreases as the test rate decreases or as the current density used increases, leading to higher embrittlement indexes. Fracture toughness dropped from 420 kJ/m2 in air to 101 kJ/m2 in the most aggressive hydrogen condition. When a current density of 0.2 mA/cm2 and saline electrolyte are used, the observed embrittlement was much lower (hydrogen embrittlement index, HE = 51 %). The fracture micromechanisms were also analyzed, revealing ductile mechanisms (microvoid coalescence) in the absence of hydrogen and brittle mechanisms (carbide-matrix interface decohesion and martensitic lath decohesion) when hydrogen was present.