Applying a new push-to-pull micro-tensile testing technique to evaluate the mechanical properties of high dose Inconel X-750

The results from a novel, micro-tensile testing technique, employing a micro-electro-mechanical system, operated in a push-to-pull configuration, to study the effects of radiation damage on Inconel X-750, are presented. Non-irradiated material, along with material irradiated to 67 dpa and 81 dpa at two irradiation temperatures, 120–280 °C and 300–330 °C, is investigated. This testing approach implements a safe, lift-out, extraction method that enables the evaluation of material tensile behavior in specific locations of radioactive components with complex geometries outside of costly hot cell protective environments. Regional cold working and grinding manufacturing processes that go undetected in bulk component testing can be evaluated in parallel with radiation damage effects. Non-irradiated specimens on the order of 1 µm × 1 µm × 2.5 µm taken from center regions of the material unaffected by processing produced yield strengths of 938 MPa and 1043 MPa, in good agreement with the bulk yield strength of Inconel X-750: 972–1070 MPa. Mechanical strengths of material irradiated to 67 dpa decreased by ~75 MPa for material irradiated at 300–330 °C and ~176 MPa for material irradiated at 120–280 °C, compared to the non-irradiated material. However, material irradiated to 81 dpa has practically identical mechanical strengths at the two irradiation temperatures, and these strengths are ~100 MPa greater than those of non-irradiated material. Average ductility of the material decreases more quickly when irradiated at 300–330 °C, from an initial value of ~15% to ~5% after 67 dpa, whereas the ductility of the material irradiated at 120–280 °C remains close to the initial value at 67 dpa and decreases to ~2% after 81 dpa.