Microstructural Origin of Residual Stress

2019-03-20T21:03:22Z (GMT) by Arijit Lodh
This thesis started with a hypothesis: "the microstructural constraints, or dislocation substructures, are essential for the residual stress". GND (geometrically necessary dislocation) density and/or in-grain misorientations were considered to represent the dislocation substructures. Residual stresses, on the other hand, were measured with multiple {hkl} GIXRD (grazing incident X-ray diffraction), micro-Laue diffraction (for single-crystal stress measurements) and residual stress ODFs (orientation distribution function). Possible correlations between substructure and residual stress evolutions were then explored experimentally and simulated numerically (with DDD (discrete dislocation dynamics) and CPFE (crystal plasticity finite element)). It was shown that the stress evolution, under different deformation modes and thermal annealing, was determined by concurrent developments in dislocation substructures. The thesis thus provides interesting insights into 'Microstructural Origin of Residual Stress'.