About this Abstract |
| Meeting |
2025 AWS Professional Program
|
| Symposium
|
2025 AWS Professional Program
|
| Presentation Title |
Analysis of the Effects of Recrystallization on Ductility-Dip Cracking Susceptibility in Ni-Cr-Fe Materials |
| Author(s) |
Anil Singh, Boian T. Alexandrov, Michael J. Mills |
| On-Site Speaker (Planned) |
Anil Singh |
| Abstract Scope |
Ni-Cr-Fe alloys are employed heavily by the nuclear power generation industry for weld overlays to minimize stress corrosion susceptibility and for weld repair. These alloys are susceptible to ductility-dip cracking (DDC), potentially making theses overlays and weld repairs unacceptable within the low flaw tolerance of the nuclear industry. Much of the investigation into mitigating DDC has been based around compositional optimization, however recent literature has pointed towards dynamic recrystallization (DRX) being a mitigating factor on DDC susceptibility.
This work aims to develop a relationship between the effects of DRX and DDC in Ni-Cr-Fe filler metals. DRX increases grain boundary tortuosity, minimizing the straight migrated grain boundaries typically associated with DDC. Recent work has found that pockets of recrystallization preferentially accumulate strain, in turn reducing the local cracking susceptibility. It is therefore hypothesized that DRX can function as a strain sink, compensating for the lack of ductility within the ductility-dip temperature range (DTR).
To test this hypothesis, Gleeble samples of typical Ni-Cr-Fe filler metals will be machined. These samples will be isothermally strained at high temperature to determine the critical strain for discontinuous dynamic recrystallization (DDRX). Ni-Cr-Fe alloys are low to medium stacking fault energy (SFE) materials hence undergoing DDRX, which have distinct high temperature stress-strain curves with discernable critical strains for the onset of DRX and steady state DRX. Once these values are determined, samples will be strained to induce varying degrees of DRX. These samples will then be strained within the DTR to just before failure and characterized for their cracking response and plastic strain distribution using optical microscopy and electron backscattered diffraction (EBSD) analysis. This work will give insight into an emerging mitigation mechanism for DDC and lay the groundwork for future work in which weld procedures are optimized to induce DRX. |
| Proceedings Inclusion? |
Undecided |