Hydrogen solubility, diffusivity and trapping in a tempered Fe–C–Cr martensitic steel under various mechanical stress states

• Published in: Materials science & engineering. A, Structural materials : properties, microstructure and processing Vol. 534; pp. 384 - 393
• Main Authors: Frappart, S., Feaugas, X., Creus, J., Thebault, F., Delattre, L., Marchebois, H.
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier B.V 01.02.2012; Elsevier
• Subjects: Applied sciences; Condensed matter: structure, mechanical and thermal properties; Elasticity and plasticity behaviours; Elasticity. Plasticity; Equations of state, phase equilibria, and phase transitions; Exact sciences and technology; Hardening. Tempering; Heat treatment; High strength low alloy (HSLA) steels; Hydrogen diffusion and trapping; Mechanical properties and methods of testing. Rheology. Fracture mechanics. Tribology; Metals. Metallurgy; Other mechanical properties; Physics; Production techniques; Solubility, segregation, and mixing; phase separation; Thermally activated processes; Hydrogen diffusion and trapping; Elasticity and plasticity behaviours; Thermally activated processes; High strength low alloy (HSLA) steels; Lattice distortion; Elasticity; Irreversible process; Plastic deformation; Precipitate; Crystal defect; Stress functions; Elastic fields; Stress relaxation; Internal stress; Tempering; Plasticity; Stress effects; Diffusion coefficient; Diffusion; Activation energy; Quenching and tempering; Atomic position; Martensitic steel; Vacancy; Permeation; Solubility; Mechanical properties; Dislocation multiplication; Diffusivity; Trapping; Mechanical stress; Classical theory
• ISSN: 0921-5093; 1873-4936
• DOI: 10.1016/j.msea.2011.11.084

► Engineering elasticity is divided into three mechanical behaviours. ► Apparent diffusion coefficient is affected in the generalized plasticity domain. ► Plasticity increases irreversibly trapped H related to dislocation creation. ► A local elastic distortion seems to affect hydrogen lattice concentration. ► Elastic field around precipitates seems to be reversible trapping sites. Electrochemical permeation test under stress conditions was carried out to determine the consequences of lattice distortion and defects on hydrogen solubility, diffusivity and trapping in a quenched and tempered martensitic steel. We focused our attention within the “engineering” elastic domain which can be divided into three domains: elasticity, micro-plasticity and generalized plasticity. The local elastic distortion associated with hydrogen atoms in lattice sites and residual vacancies seems to affect hydrogen lattice concentration. The hydrogen trapped in elastic fields shows a complex behaviour as a function of stress related to a possible internal relaxation of stresses around precipitates with the occurrence of plasticity. The plastic deformation caused a substantial increase of irreversible trapping sites in relation with the dislocation multiplication. Apparent diffusion coefficient decreased in this deformation domain in agreement with classical trapping models.