论文和技术资料

Duplex stainless steels are commonly used in oil and gas production due to their high mechanical properties and good resistance to stress corrosion cracking. In particular, URTM 2507 (EN 1.4410) exhibits good resistance to stress corrosion cracking in an acidic environment containing chlorides at low partial pressures of hydrogen sulfide (H2S). At high H2S partial pressures, samples do not exhibit cracking, but the selective dissolution of a phase is visible on the sample surface. Even if no cracking occurs, surface dissolution is sufficient to conclude that the stress corrosion cracking resistance is not suitable for this environment. Therefore, a deeper understanding of the dissolution mechanism is necessary to further expand the application range of the grade.

The study of the dissolution mechanism was explored using a numerical approach with COMSOL Multiphysics® software. The model has been adapted from “Localized corrosion using phase field model” example from Application Libraries. The actual microstructure of the grade was implemented in the model after some image processing. Then, the electrochemical behavior of each phase (austenite and ferrite) in H2S environment was determined using laboratory-synthesized castings and implemented in the model. Using a phase-field methodology, the dissolution kinetics and morphology were studied as a function of several microstructural parameters (sampling direction, grain size). The model made it possible to quantify the effect of dissolution on the initiation of stress corrosion cracking in the grade.