Using local GND density to study SCC initiation

Isothermal and thermomechanical fatigue crack growth behavior of 316LN stainless steel under load‐ and strain‐controlled modes

“…GND values represent the quantity of generated dislocations within the grains, serving as an indicator of microscopic deformation and damage conditions. It is well‐established that the accumulation of GND is a necessary condition for the initiation and propagation of fatigue cracks 34,43,44 . Crack tips tend to exhibit GND accumulation due to heightened local deformation and strain gradients 39 .…”

“…It is well-established that the accumulation of GND is a necessary condition for the initiation and propagation of fatigue cracks. 34,43,44 Crack tips tend to exhibit GND accumulation due to heightened local deformation and strain gradients. 39 Furthermore, the published references reported that GND accumulation leads to increased hardening and regional stress concentration at the crack tip, which is positively correlated with the crack growth rate.…”

On the role of intergranular nanocavities in long-term stress corrosion cracking of Alloy 690

“…This method is based on the method suggested by Wilkinson et al [29] and Pantleon [30] and built on the local dislocation density tensor introduced by Nye [31] . More details about its application to IGSCC can be found in [32] . Given the high level of deformation caused by the prior cold-work and the associated challenges choosing a suitable reference within a grain, the GND calculations in this work are not based on high-resolution cross-correlation but on a Hough-based indexing routine instead [33] .…”

Effect of sample thinning on strains and lattice rotations measured from Transmission Kikuchi diffraction in the SEM

“…This crosscorrelation approach (HR-TKD in this case), can be used to measure strain and rotation fields (thereby a GND density estimation for deformation) in small areas not accessible by traditional EBSD, via a site-specific FIB liftout or by electropolishing [22]. An example of the potential of this technique is for the study of localised deformation around crack tips (especially in stress corrosion cracking, where the cracks are sub-surface) [24,25] or around smaller microstructural features that need a high spatial resolution for imaging/measurement [26].…”