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Description
Austenitic stainless steel is used as a container material for spallation neutron source targets such as the American spallation neutron source (SNS), the Japanese spallation neutron source (J-PARC), and the Chinese spallation neutron source (CSNS), due to its excellent high-temperature performance, welding performance and corrosion resistance. There are some researches on the performance of austenitic stainless steel after proton and neutron mixed irradiation, but few reports on the irradiation performance of austenitic stainless steel after welding. In order to study the mechanical property changes of SS316LN after welding and irradiation, SS316LN and SS316LN electron beam welding (EBW) samples were irradiated in the second experiment of the SINQ Target Irradiation Program (STIP-II) in a dose range of 7.5dpa-19.5dpa and a temperature range of 103-328 °C.
Microscopic morphology observation, hardness and tensile test were conducted on both SS316LN and SS316LN-EBW samples. The microstructure analysis of the welding area shows that the welding center area is composed of fine equiaxed grains, with columnar grains on both sides. The width of the fusion and heat affected zone is approximately 4mm. Compared to the 316LN samples, the total elongation of the welded samples decreased significantly after irradiation at the same dose. However, the tensile strength was similar. At 16.3dpa, the total elongation of the SS316LN-EBW samples decreased to 8% when tested at 250 °C. At 19.5dpa, the total elongation decreased to 6% when tested at 300 °C. For both SS316LN and SS316LN-EBW samples of 11.2-19.5 dpa, the strength and elongation remained no changes when tested at 200-300 °C. Fractography results showed ductile fracture mode for the 19.5 dpa sample tested at 300°C. The size of the ductile dimples on the fracture surface of welded samples is larger than that of non-welding samples.
| Themes for the contribution | 3 Post-irradiation examination: |
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