Early stages in the formation of dislocation microstructures during low-strain fatigue were analyzed by using 3-dimensional discrete dislocation dynamics modelling. Simulations were performed for various conditions of loading amplitude and grain size. Dislocation microstructures, and the associated mechanical behavior, were accurately reproduced under single-slip and double-slip loading conditions. The resultant microstructures were analyzed quantitatively in terms of the number of slip bands per grain, band thickness and band spacing. The simulations demonstrated the crucial role which was played by cross-slip both in the initial spreading of strain inside the grain, and in subsequent strain localization in the form of slip bands. A detailed scheme was proposed for persistent slip band formation.

Low-Strain Fatigue in AISI316L Steel Surface Grains - a Three-Dimensional Discrete Dislocation Dynamics Modelling of the Early Cycles I. Dislocation Microstructures and Mechanical Behaviour. C.Déprés, C.F.Robertson, M.C.Fivel: Philosophical Magazine, 2004, 84[22], 2257-75