Abstract
Advanced Fatigue Methodologies (AdFaM), a joint project
of European research laboratories, vendors and plant
operators, was launched in 2014 to build on the results
from recent laboratory studies of fatigue behavior of
austenitic stainless steels under NPP-relevant conditions
that showed improved lifetimes compared to the best fit
to test data presented in NUREG/CR-6909, and to further
investigate transferability between specimen test results
and the fatigue behavior of NPP components during plant
operation. In particular, AdFaM has focused on an
empirical and mechanistic investigation of the effects of
hold times on fatigue life. A small number of previous
test results suggest an increase in fatigue life for
stabilized grades of austenitic stainless steel when hold
times (ranging from several hours to days) are introduced
into a test between periods of straincontrolled cyclic
loading. Tests incorporating hold times may be more
representative of material behavior in NPPs, where
temperature transients due to start-ups, shutdowns and
major power changes may be separated by long periods of
steady state operation. Under AdFaM, fatigue endurance
tests incorporating hold times have been completed on
stabilized and non-stabilized stainless steel grades
(Types 304L and 347) and the mechanisms responsible for
the observed variations in fatigue life have been
investigated using a range of microscopy techniques.
Results confirm a significant extension of fatigue life
due to hold times in both stabilized and non-stabilized
grades. Life extension appears to be linked to hold
hardening observed in cyclic behavior, and this link has
been investigated through microstructural
characterization of fatigue specimens examined before and
after holding at elevated temperature. This project helps
to improve the understanding of transferability of
results from small specimen tests (without hold times) to
analysis of NPP components and provides insights that
will contribute towards continuing development of fatigue
design curves and analysis methods in Design Codes such
as ASME Code Section III and KTA 3201/3211. The AdFaM
project is now complete. The valuable results and
insights gained from this work demonstrate the
significant benefits of collaborative research between
various industrial and academic partners in the area of
fatigue of NPP materials.
| Original language | English |
|---|---|
| Title of host publication | Proceedings of ASME 2016 Pressure Vessels and Piping Conference |
| Publisher | American Society of Mechanical Engineers (ASME) |
| ISBN (Print) | 978-0-7918-5035-0 |
| DOIs | |
| Publication status | Published - 2016 |
| MoE publication type | A4 Article in a conference publication |
| Event | ASME 2016 Pressure Vessels and Piping Conference - Vancouver, Canada Duration: 17 Jul 2016 → 21 Jul 2016 |
Conference
| Conference | ASME 2016 Pressure Vessels and Piping Conference |
|---|---|
| Country/Territory | Canada |
| City | Vancouver |
| Period | 17/07/16 → 21/07/16 |