Slow strain rate tensile tests on irradiated austenitic stainless steels in simulated light water reactor environments

Irradiation stress corrosion cracking (IASCC) is a critical degradation mechanism for reactor internal components that contributes to the safe and economic operation of reactors. As nuclear power plants age and irradiation dose increases, IASCC becomes an increasingly important issue because of its potential impact on the integrity of reactor internal components. In this study, slow strain rate tensile tests were conducted on irradiated tensile specimens at strain rates between 3 and 7 × 10−7 s−1 to evaluate cracking susceptibility of austenitic stainless steels in simulated light water reactor (LWR) environments. Significant increases in yield strength were observed for all irradiated specimens and a dose dependence of irradiation hardening was obtained at temperatures relevant to LWRs. Ductility and strain hardening capability were also found decrease rapidly with the increase of dose. After the tests, the specimens were examined using a scanning electron microscopy to characterize fracture morphology. The area fractions of non-ductility fracture were used to evaluate the IASCC susceptibility along with the tensile properties. IASCC susceptibility was also compared for several stainless steels irradiated in the Halden and BOR-60 reactors. A possible neutron spectrum effect was discussed.