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

Hot isostatic pressing (HIPing) of powder is considered as a tentative manufacturing method for primary wall components of thermonuclear reactors. In the present work some mechanical properties of specimens from HIPed powder as well as from wrought, reference type 316 LN international thermonuclear experimental reactor (ITER) grade steel have been compared. Tensile, low cycle fatigue and fracture toughness tests were performed after neutron irradiation to a dose of 0.7 dpa at 290°C. The tensile properties in the unirradiated condition were found to be almost identical for the two materials. After irradiation the HIPed material showed a slightly increased hardening. No significant difference in fatigue endurance was observed. However, the fracture toughness tests showed a greatly reduced toughness of the particular HIPed material used in this investigation as compared to the wrought steel. Valid J1c data could not be obtained owing to specimen size limitations. Micrographs are provided of the fracture surfaces.