NSUF 22-4437: Neutron Irradiation Effects on the Tensile Properties of Wire Arc Additive Manufactured Grade 91 Steel
The ferritic martensitic (FM) alloy Grade 91 is a candidate material for advanced fission reactors. Additive manufacturing (AM) has been explored to increase Grade 91’s range of application temperatures and customize its radiant tolerant microstructure features. Efforts spearheaded at Oak Ridge National Laboratory (ORNL) led to the second ever recorded successful printing of Grade 91 via wire arc AM (WAAM). The microstructure of the unirradiated WAAM G91 specimens have been fully characterized and provide promising results on the material’s mechanical properties at elevated temperatures. By creating finer microstructural features, WAAM resulted in increased strength without sacrificing ductility as compared to wrought Grade 91.
Though the unirradiated properties of WAAM Grade 91 are promising, an investigation of WAAM Grade 91’s behavior under neutron irradiation is necessary for future consideration for fleet deployments. This work proposes conducting room temperature tensile tests on WAAM Grade 91 specimens that have been irradiated in the High Flux Isotope Reactor (HFIR) to 0.7 and 2.1 dpa at 300±50°C. Three conditions of WAAM Grade 91 were irradiated: as-printed with SS-J2 specimens taken from the X direction, as-printed with SS-J2 specimens taken from the Z direction, and heat-treated WAAM Grade 91 (1100°C/30 min + 760°C/60 min) taken from the X direction. The tensile tests will help determine WAAM Grade 91’s property evolution in-reactor in its as-printed and heat-treated states. Differences in behavior caused by anisotropy will also be elucidated by comparing the X- and Z-cuts of the as-printed WAAM Grade 91. The tensile testing apparatus will be equipped with Digital Image Correlation (DIC) to accurately measure strain rate during testing and provide data on strain hardening in WAAM FM steels as a function of dose, specimen build direction, and heat treatment. Scanning electron microscopy (SEM) will also be employed to image fracture surfaces to correlate true stress-strain data with failure mechanism.
This work would be the first ever to explore the neutron irradiated tensile properties of WAAM Grade 91, providing significant contributions to the study of AM for advanced reactor applications. Particularly, properties under low dose are of interest to capture the early response of WAAM Grade 91 to neutron irradiation and lay the groundwork for understanding its irradiation behavior over a wide range of doses. The work from this RTE will result in a peer-reviewed publication, with a similar format to Ref. [1].
References [1] K.G. Field, S.A. Briggs, K. Sridharan, R.H. Howard, Y. Yamamoto, Mechanical properties of neutron-irradiated model and commercial FeCrAl alloys, Journal of Nuclear Materials. 489 (2017) 118–128. https://doi.org/10.1016/j.jnucmat.2017.03.038.
Additional Info
| Field | Value |
|---|---|
| Abstract | The ferritic martensitic (FM) alloy Grade 91 is a candidate material for advanced fission reactors. Additive manufacturing (AM) has been explored to increase Grade 91’s range of application temperatures and customize its radiant tolerant microstructure features. Efforts spearheaded at Oak Ridge National Laboratory (ORNL) led to the second ever recorded successful printing of Grade 91 via wire arc AM (WAAM). The microstructure of the unirradiated WAAM G91 specimens have been fully characterized and provide promising results on the material’s mechanical properties at elevated temperatures. By creating finer microstructural features, WAAM resulted in increased strength without sacrificing ductility as compared to wrought Grade 91. Though the unirradiated properties of WAAM Grade 91 are promising, an investigation of WAAM Grade 91’s behavior under neutron irradiation is necessary for future consideration for fleet deployments. This work proposes conducting room temperature tensile tests on WAAM Grade 91 specimens that have been irradiated in the High Flux Isotope Reactor (HFIR) to 0.7 and 2.1 dpa at 300±50°C. Three conditions of WAAM Grade 91 were irradiated: as-printed with SS-J2 specimens taken from the X direction, as-printed with SS-J2 specimens taken from the Z direction, and heat-treated WAAM Grade 91 (1100°C/30 min + 760°C/60 min) taken from the X direction. The tensile tests will help determine WAAM Grade 91’s property evolution in-reactor in its as-printed and heat-treated states. Differences in behavior caused by anisotropy will also be elucidated by comparing the X- and Z-cuts of the as-printed WAAM Grade 91. The tensile testing apparatus will be equipped with Digital Image Correlation (DIC) to accurately measure strain rate during testing and provide data on strain hardening in WAAM FM steels as a function of dose, specimen build direction, and heat treatment. Scanning electron microscopy (SEM) will also be employed to image fracture surfaces to correlate true stress-strain data with failure mechanism. This work would be the first ever to explore the neutron irradiated tensile properties of WAAM Grade 91, providing significant contributions to the study of AM for advanced reactor applications. Particularly, properties under low dose are of interest to capture the early response of WAAM Grade 91 to neutron irradiation and lay the groundwork for understanding its irradiation behavior over a wide range of doses. The work from this RTE will result in a peer-reviewed publication, with a similar format to Ref. [1]. References [1] K.G. Field, S.A. Briggs, K. Sridharan, R.H. Howard, Y. Yamamoto, Mechanical properties of neutron-irradiated model and commercial FeCrAl alloys, Journal of Nuclear Materials. 489 (2017) 118–128. https://doi.org/10.1016/j.jnucmat.2017.03.038. |
| Award Announced Date | 2022-06-14T07:26:28.393 |
| Awarded Institution | None |
| Facility | None |
| Facility Tech Lead | Kory Linton |
| Irradiation Facility | None |
| PI | Theresa Green |
| PI Email | [email protected] |
| Project Type | RTE |
| RTE Number | 4437 |