NSUF 25-5388: Evaluating Irradiation-Induced Degradation of Phase Boundary Strength in Cast Stainless Steels
This project addresses a critical knowledge gap in predicting fracture toughness degradation of cast stainless steels (CASS) under high-dose neutron irradiation—key for ensuring structural integrity in extended-life nuclear reactors. Duplex stainless steels, including CASS and austenitic welds, experience microstructural changes in the ferrite phase due to thermal aging and irradiation, leading to hardening and altered load partitioning between ferrite and austenite phases. This increases the risk of brittle fracture in the ferrite, especially at high irradiation doses. Current fracture toughness data for irradiated stainless steels are largely limited to doses below 5 dpa, while end-of-life doses may exceed 20 dpa. To reduce this uncertainty, we propose a data-driven approach combining experimental testing, finite element (FE) modeling, and Bayesian neural networks (BNNs) to predict fracture behavior in irradiated CASS. A key gap in FE simulations is the lack of interfacial strength data between ferrite and austenite phases. We will directly measure this using in-situ micro-tensile testing on irradiated CF3 CASS samples (3–20 dpa) prepared via FIB lift-out and tested on MEMS-based Push-to-Pull devices using the Hysitron PI 88 PicoIndenter. The work will be completed in nine months, with facility access at CAES MaCS. The project is led by Dr. Yong Yang (UF), with contributions from PhD student Alejandro Corrales and co-PI Dr. Yiren Chen (ANL). Deliverables include a final report to NSUF, conference presentations, and peer-reviewed publications to support improved fracture toughness predictions for reactor safety assessments.
Additional Info
| Field | Value |
|---|---|
| Awarded Institution | University of Florida |
| DOI | 10.46936/NSUF/60015373 |
| Embargo End Date | 2027-09-03 |
| Facility Tech Lead | Mukesh Bachhav |
| NSUF Call | FY 2025 RTE 2nd Call |
| PI | Yong Yang |
| PIE Facilities | Microscopy and Characterization Suite |
| Prep Facilities | Microscopy and Characterization Suite |
| Project Member | Yong Yang, Associate Professor - University of Florida (https://orcid.org/0000-0002-0247-6219) |
| Project Member | Yiren Chen - Argonne National Laboratory (https://orcid.org/0000-0002-4153-1532) |
| Project Type | RTE |