Abstract
Inhomogeneous microstructures, e.g. grain size,
dislocation density etc., always occur in welded
structures. Varying manufacturing methods leading to
complex strain paths result in highly varying cold-work
and consequent residual strains. The role of strain
localization is not widely familiar as a precursor for
failure and its mechanisms are still not fully known. If
strain localization occurs by a creep mechanism, the
incubation time for crack initiation can be very long, as
frequently observed in NPPs.
EBSD employed to measure strain distributions in a Type
304 austenitic stainless steel weld shows a high
variation in residual strain distribution, which was
verified by hardness measurements as well as with
residual stress measurements. Strain localization
investigations are also performed on specimens from Super
Slow Strain Rate Test using a very slow strain rate of 1
o 10-8 s-1. This is in the creep strain rate range, where
diffusion along dislocation cores and grain boundaries
occur together with grain boundary sliding. SSSRT's were
performed on sensitized Type 304 austenitic stainless
steel either with or without cold deformation in
simulated BWR environment. To increase the understanding
of IGSCC and the role of localization of deformation,
versatile techniques like FE-SEM/EBSD and TEM were used
to characterize the materials after the extremely slow
strain rate tests. Local variation in the amount of
surface cold-work seems to affect crack initiation.
During crack growth, strain localization occurs at grain
boundaries ahead of the crack tips. Local variations of
grain size also affect strain localization.
| Original language | English |
|---|---|
| Title of host publication | Proceedings of the 14th International Conference on Environmental Degradation of Materials in Nuclear Power Systems Water Reactors |
| Publisher | American Nuclear Society (ANS) |
| Pages | 333-344 |
| Volume | 1 |
| ISBN (Print) | 978-161738853-8 |
| Publication status | Published - 2009 |
| MoE publication type | A4 Article in a conference publication |
| Event | 14th International Conference on Environmental Degradation of Materials in Nuclear Power Systems - Virginia Beach, United States Duration: 23 Aug 2009 → 27 Aug 2009 |
Conference
| Conference | 14th International Conference on Environmental Degradation of Materials in Nuclear Power Systems |
|---|---|
| Country/Territory | United States |
| City | Virginia Beach |
| Period | 23/08/09 → 27/08/09 |