| About this Abstract |
| Meeting |
2023 AWS Professional Program
|
| Symposium
|
2023 AWS Professional Program
|
| Presentation Title |
Stress Relaxation Cracking Susceptibility in 347H SS Welds and Their Repairs |
| Author(s) |
Timothy Pickle, Yu Hong, Jeffrey R. Bunn, E. Andrew Payzant, Chad Augustine, Judith Vidal, Zhenzhen Yu |
| On-Site Speaker (Planned) |
Timothy Pickle |
| Abstract Scope |
347H SS has a combination of good creep strength and sensitization resistance compared to other 3XX SS grades for mildly corrosive, elevated temperature applications. Stress relaxation cracking (SRC) may take place in 347H SS welds especially when using matching E/ER347 filler in the as-welded condition during elevated temperature service. Post weld heat treatment (PWHT) has been prescribed to mitigate SRC. However, cracking could potentially occur during PWHT due to the competition between bulk stress relaxation and localized plastic strain accumulation along precipitate free zones within grain boundaries. In this work, residual stress distributions, microstructures (including lab weld, field weld after a few years in service, post-weld heat treated weld and repairs) and their corresponding SRC susceptibility are thoroughly investigated to provide insights on their correlations. Residual stress profiles were obtained through finite element (FE) simulation and neutron diffraction residual stress mapping using the high intensity diffractometer (HIDRA/HB-2B) at the High Flux Isotope Reactor (HFIR) at Oak Ridge National Laboratory (ORNL). The information obtained provides critical guidance for the design of reheat cracking tests using a Gleeble machine. Critical stresses as a function of temperature were identified for the heat affected zone (HAZ), E347 fusion zone (FZ) FZ and E16.8.2 FZ in the as-welded condition. The cracking susceptibility in E347 FZ was demonstrated to be higher than the other cases due to a generally lower threshold stress at all testing temperatures. PWHT at 950°C for 3 h led to improvement on cracking susceptibility. Repair weld specimens using matching filler showed similar susceptibility to SRC compared to initial welded condition. In comparison, repair welds with alternative E16.8.2 filler exhibited improved resistance to SRC. |
| Proceedings Inclusion? |
Undecided |