NSUF 17-906: Radiation Tolerance of Friction Stir Welded Ferritic Oxide Dispersed Steel under Ion Irradiation
The objective of this work is to examine the effect of high damage levels of radiation on the microstructure of friction stir welded (FSW) ferritic oxide dispersion strengthened (ODS) steel MA956. ODS alloys offer high strength, creep resistance as well as dimensional stability under irradiation, which makes them attractive candidates for structural and fuel cladding applications in advanced reactor concepts. The radiation tolerance is due to the high sink strength that arises from the high density of dispersoids (Y-Al-O) throughout the matrix. However, with the addition of any welding process, specifically friction stir welding (FSW) in this case, the dispersoids are expected to coarsen due to an Ostwald ripening processing. To date there has been little examination of the effect of welding on irradiation tolerance of ODS alloys, which represents a significant gap in knowledge necessary for the manufacturing and implementation of advanced fuel cladding. MA956, the alloy to be examined in this study, has been well characterized in the as-received and welded condition in terms of mechanical properties as well as dispersoid and grain behavior. From the unirradiated work, the coarsened dispersoids, as a result of welding, are expected to result in decreased strength and susceptibility to radiation tolerance due to the overall decreased sink strength. Therefore, additional data comparing both the as-received and welded material as a function of increasing dose is necessary to determine the degree to which there is loss of radiation tolerance. This project will focus on MA956 in the as-received and welded condition irradiated at 450oC to 50, 100 and 200 dpa by a previous funding source. The microstructural characterization will be performed on FIB samples in the STEM and will focus on determining the dispersoid evolution, dislocation microstructure, formation of any new precipitates as well as characterization of any voids that may form. Particular consideration will be to understanding the sink strength evolution of all microstructure features. This project will provide a first attempt at a systematic understanding of the negative effects of welding on irradiated material performance, a novel and valuable area which is of growing interest to the Department of Energy Office of Nuclear Energy, as advanced clad materials are selected and eventually manufactured for Gen IV reactors.
Additional Info
| Field | Value |
|---|---|
| Abstract | The objective of this work is to examine the effect of high damage levels of radiation on the microstructure of friction stir welded (FSW) ferritic oxide dispersion strengthened (ODS) steel MA956. ODS alloys offer high strength, creep resistance as well as dimensional stability under irradiation, which makes them attractive candidates for structural and fuel cladding applications in advanced reactor concepts. The radiation tolerance is due to the high sink strength that arises from the high density of dispersoids (Y-Al-O) throughout the matrix. However, with the addition of any welding process, specifically friction stir welding (FSW) in this case, the dispersoids are expected to coarsen due to an Ostwald ripening processing. To date there has been little examination of the effect of welding on irradiation tolerance of ODS alloys, which represents a significant gap in knowledge necessary for the manufacturing and implementation of advanced fuel cladding. MA956, the alloy to be examined in this study, has been well characterized in the as-received and welded condition in terms of mechanical properties as well as dispersoid and grain behavior. From the unirradiated work, the coarsened dispersoids, as a result of welding, are expected to result in decreased strength and susceptibility to radiation tolerance due to the overall decreased sink strength. Therefore, additional data comparing both the as-received and welded material as a function of increasing dose is necessary to determine the degree to which there is loss of radiation tolerance. This project will focus on MA956 in the as-received and welded condition irradiated at 450oC to 50, 100 and 200 dpa by a previous funding source. The microstructural characterization will be performed on FIB samples in the STEM and will focus on determining the dispersoid evolution, dislocation microstructure, formation of any new precipitates as well as characterization of any voids that may form. Particular consideration will be to understanding the sink strength evolution of all microstructure features. This project will provide a first attempt at a systematic understanding of the negative effects of welding on irradiated material performance, a novel and valuable area which is of growing interest to the Department of Energy Office of Nuclear Energy, as advanced clad materials are selected and eventually manufactured for Gen IV reactors. |
| Award Announced Date | 2017-04-26T10:09:30.907 |
| Awarded Institution | None |
| Facility | None |
| Facility Tech Lead | Yaqiao Wu |
| Irradiation Facility | None |
| PI | Elizabeth Getto |
| PI Email | [email protected] |
| Project Type | RTE |
| RTE Number | 906 |