Mechanical properties of hot isostatic pressed type 316LN steel after irradiation to 2.5 dpa

Hot isostatic pressing (HIP) of powder is considered as a tentative manufacturing method for primary wall components of ITER. The mechanical properties of unirradiated specimens and specimens irradiated to a dose of 0.7 dpa at 290 °C from HIPed powder and from wrought, reference, type 316 LN ITER grade steel have been reported earlier. Complementary tensile, low cycle fatigue and fracture toughness tests of the materials were performed after neutron irradiation to a dose of 2.5 dpa at 290 °C. The results of these tests compared to those reported previously indicate that at the lower dose the HIPed steel shows more irradiation hardening and less elongation compared to the wrought material but after 2.5 dpa the properties are almost identical again. No significant difference in fatigue endurance (at a single strain range of 0.8%) was observed at a dose of 0.7 dpa. After 2.5 dpa the HIPed steel has a shorter average life, but the variation in the results was less compared to the wrought reference steel. The wrought steel behaved noticeably tougher than the HIPed after 0.7 and 2.5 dpa (JQ≈3×JQHIP). The two steels fractured in a ductile mode. Valid J1c data could not be obtained owing to specimen size limitations.