Hydrogen trapping in an API 5L X60 steel

• Published in: Corrosion science 2012, Vol.54, p.106-118
• Main Authors: Castaño Rivera, P., Ramunni, V.P., Bruzzoni, P.
• Format: Article
• Language: English
• Subjects: A. Steel; API; Applied sciences; B. Hydrogen permeation; B. Modelling studies; C. Effects of strain; Cold rolling; Corrosion; Corrosion environments; Density; Diffusion; Exact sciences and technology; Fittings; High strength low alloy steels; Metals. Metallurgy; Steels; Trapping
• ISSN: 0010-938X; 1879-0496
• DOI: 10.1016/j.corsci.2011.09.008

► Hydrogen diffusion and trapping parameters were determined for an API 5L X60 steel. ► Parameters were obtained by using a model of saturable traps in local equilibrium. ► Apparent diffusion coefficient reflects weak trap effects. ► The use of an apparent diffusion coefficient improves calculation efficiency. ► Either weak or strong trap densities are increased with plastic deformation. Electrochemical hydrogen permeation tests were performed on an API 5L X60 steel to study trapping and diffusion properties in the as-received (AR) and in a cold-rolled (CR) state, at 30, 50 and 70 °C. Hydrogen trapping was characterized by assuming saturable traps in local equilibrium. Binding energies (Δ G) and trap densities ( N) were determined by fitting a trapping theoretical model to experimental data. Both conditions AR and CR present a high density of weak traps |Δ G| < 35 kJ/mol, namely N = 1.4 × 10 −5 and 7.9 × 10 −4 mol/cm 3 respectively. Strong trapping sites were detected (−72 < Δ G < −57 kJ/mol) and their densities increased markedly after cold-rolling.