NSUF 18-1441: Effects of Welding on Radiation-Enhanced Precipitation in FeCrAl Alloys
The objective of this project is to investigate the distribution of solute elements Cr, Al, and Mo in an un-irradiated Fe-13Cr-5Al-2Mo (wt.%, C35M) weldment, including base material (BM), heat affected zone (HAZ), and fusion zone (FZ), as well as a' precipitation in C35M weldment after 7.0 dpa neutron irradiation at LWR relevant temperature of near 330 °C. Previous RTE activities have revealed that after neutron irradiation up to 1.8 dpa at nominally similar temperature, the radiation-enhanced precipitation behavior of Cr-rich a' phase in the weldment of C35M varied significantly from BM to HAZ and FZ. Statistical analysis indicates that the number density of a' in both HAZ and FZ was only one third of that in BM, whereas the average size of a' in HAZ and FZ was ~30% larger than that in BM. This project will provide comprehensive understanding on how welding altered the initial distribution of solute atoms in HAZ and FZ prior to irradiation, which consequently altered precipitation behavior dramatically at low dose (e.g., 1.8 dpa). Furthermore, since a' precipitation would likely reach maturity at or well before 7.0 dpa irradiation, the effects of welding on long-term precipitation will also be revealed, which largely determines the end-of-life performance of the fuel cladding closure welds. This project requires advanced microanalysis techniques including focused ion beam (FIB) sample fabrication and atom probe tomography (APT). FIB fabrication is required to create the samples necessary to perform APT analysis. APT analysis provides data that allows for quantification and visualization of the morphology, size, number density, and composition of the precipitates contained within the bulk matrix and is the de facto method for nano-scale precipitate characterization that requires chemical signatures. APT data collected from weldments of a candidate FeCrAl alloy prior to neutron irradiation as well as after high irradiation dose of 7.0 dpa will provide insight into influences of welding on altered precipitation behavior in HAZ and FZ compared to BM and resulting mechanical performance, thereby addressing the current knowledge gaps in the FeCrAl alloy class. The fundamental understanding of welding effects in the FeCrAl alloy class will increase the technology readiness level of FeCrAl alloys. On the whole, information gained from the proposed work will have broad reaching impacts on ferrous-based alloy development for nuclear power generation including cladding, structural materials, and corrosion barrier systems in fission systems. This project is predicted to take no more than 5 months to complete and the needed workflow to meet this timeline is already well established. Fabrication of APT samples using FIB techniques is estimated to take no more than 2 months. Data collection of APT samples is expected to take less than two weeks. Data analysis and reporting will take approximately 2 months from the date of initial data collection.
추가 정보
| 필드 | 값 |
|---|---|
| Abstract | The objective of this project is to investigate the distribution of solute elements Cr, Al, and Mo in an un-irradiated Fe-13Cr-5Al-2Mo (wt.%, C35M) weldment, including base material (BM), heat affected zone (HAZ), and fusion zone (FZ), as well as a' precipitation in C35M weldment after 7.0 dpa neutron irradiation at LWR relevant temperature of near 330 °C. Previous RTE activities have revealed that after neutron irradiation up to 1.8 dpa at nominally similar temperature, the radiation-enhanced precipitation behavior of Cr-rich a' phase in the weldment of C35M varied significantly from BM to HAZ and FZ. Statistical analysis indicates that the number density of a' in both HAZ and FZ was only one third of that in BM, whereas the average size of a' in HAZ and FZ was ~30% larger than that in BM. This project will provide comprehensive understanding on how welding altered the initial distribution of solute atoms in HAZ and FZ prior to irradiation, which consequently altered precipitation behavior dramatically at low dose (e.g., 1.8 dpa). Furthermore, since a' precipitation would likely reach maturity at or well before 7.0 dpa irradiation, the effects of welding on long-term precipitation will also be revealed, which largely determines the end-of-life performance of the fuel cladding closure welds. This project requires advanced microanalysis techniques including focused ion beam (FIB) sample fabrication and atom probe tomography (APT). FIB fabrication is required to create the samples necessary to perform APT analysis. APT analysis provides data that allows for quantification and visualization of the morphology, size, number density, and composition of the precipitates contained within the bulk matrix and is the de facto method for nano-scale precipitate characterization that requires chemical signatures. APT data collected from weldments of a candidate FeCrAl alloy prior to neutron irradiation as well as after high irradiation dose of 7.0 dpa will provide insight into influences of welding on altered precipitation behavior in HAZ and FZ compared to BM and resulting mechanical performance, thereby addressing the current knowledge gaps in the FeCrAl alloy class. The fundamental understanding of welding effects in the FeCrAl alloy class will increase the technology readiness level of FeCrAl alloys. On the whole, information gained from the proposed work will have broad reaching impacts on ferrous-based alloy development for nuclear power generation including cladding, structural materials, and corrosion barrier systems in fission systems. This project is predicted to take no more than 5 months to complete and the needed workflow to meet this timeline is already well established. Fabrication of APT samples using FIB techniques is estimated to take no more than 2 months. Data collection of APT samples is expected to take less than two weeks. Data analysis and reporting will take approximately 2 months from the date of initial data collection. |
| Award Announced Date | 2018-05-17T11:07:58.19 |
| Awarded Institution | None |
| Facility | None |
| Facility Tech Lead | Yaqiao Wu |
| Irradiation Facility | None |
| PI | Dalong Zhang |
| PI Email | [email protected] |
| Project Type | RTE |
| RTE Number | 1441 |