Influence of non-homogeneous microstructure on hydrogen diffusion and trapping simulations near a crack tip in a welded joint

摘要: Abstract Hydrogen assisted fracture near welds is the result of a combination microstructural changes and accumulation hydrogen. With aim predicting local hydrogen concentrations, redistribution crack tip simulated using Boundary Layer approach diffusion modelling modified by trapping phenomena. The non-homogeneous geometry includes layers that reproduce weld metal, heat affected zones base metal 2.25Cr-1Mo steel; mechanical properties have been extracted from references. transport model here considered involves stress dependency affects concentrations; thus, possible interaction between constraint effects associated to graded material with entry studied. Results show effect not significative for loading widths assigned (2.5 5 mm); however, HAZ-centred crack, higher hydrostatic peak corresponding increase in lattice are found. A two-type process also simultaneously dislocation microstructure delayed diffusion. weakly trapped dislocations it added concentration obtain measure diffusible while effective diffusivity strongly reduced deeply Differences environmental or internal sources expected be more accurately captured because stress-dependent boundary conditions implemented uptake.