Effect of test temperature on mechanical properties of austenitic 0.12C18Cr10NiTi and 0.08C16Cr11Ni3Mo steels irradiated by fast neutrons in the BN-350 reactor

12C18Cr10NiTi and 0.08C16Cr11Ni3Mo austenitic steels serve as structural materials for fuel assembly covers in the BN-350 fast reactor, as well as for the covers of transport packagings for transportation and storage of spent nuclear fuel (SNF). To predict failure of these elements, it is of paramount importance to know their mechanical properties at elevated temperatures after in-pile irradiation. We performed tensile and creep tests at room temperature (RT), 350 °C and 450 °C of irradiated samples cut from the higher half of fuel duct pipes of the BN-350 reactor. A non-monotonic temperature dependence of tensile strength, yield stress, and relative elongation was shown. Microstructural investigation revealed the origin of this dependence lies in the different distribution of carbides and is also associated with the formation of α'-phase. © 2017 Trans Tech Publications, Switzerland.