[SY-F14] Symposium F-14

[SY-F14] Hydrogen Transport and Thermal Desorption in Multiphase Steels

^○Andrej Turk¹, Pedro E.J. Rivera-Díaz-del-Castillo², Enrique Galindo-Nava¹ (1.University of Cambridge, UK, 2.Lancaster University, UK)

Hydrogen diffusion is modelled using a 2D multi-trap diffusion model. It takes into account trapping on crystal defects (dislocations, carbides and grain boundaries), as well as the presence of secondary phases with different hydrogen diffusivity and solubility. Secondary phases introduce local discontinuities in the hydrogen concentration field and this problem has not been modelled systematically in multiphase steels. The first studied case is a 2D simulation of thermal desorption in high-strength bainitic steels with varying fractions of retained austenite where the effects of austenite morphology are highlighted. The second case is a different thermal desorption problem in a high-temperature iron-nickel FCC alloy in which grain boundaries are known to be fast diffusion pathways. As the boundaries require a prohibitively fine discretisation in 2D, the microstructure is parameterised and reduced to 1D. The effects of grain boundary properties on hydrogen diffusion are studied. Lastly, we explore the application of the model to other interstitial elements and metallic systems, where the morphology and spatial arrangement of the microstructure strongly affects elemental diffusion.