Coupled Modeling of Anisotropic Stress-Induced Diffusion and Trapping of Nitrogen in Austenitic Stainless Steel during Nitriding and Thermal Annealing

In this paper, nitrogen diffusion is investigated in single-crystalline austenitic stainless steel during modified layer formation and thermal annealing. A generalized system of equations derived within a thermodynamic framework from Fick’s laws, which describe flux under multiple driving forces, including concentration gradient the hydrostatic stress. Trapping detrapping phenomena are considered model, distinguished depending on whether lattice or trapping site. Furthermore, effects anisotropic elasticity single-crystal stress field investigated. The proposed model used to simulate transportation process AISI 316L ion beam nitriding after isothermal annealing at three different crystalline orientations. results our theoretical predictions compared with experimental taken literature. It shown that annealing, becomes significantly slower than nitriding. coefficient process, decreases by factors 4.3, 3.3, 2.5 for orientations (001), (011), (111), respectively.