TWIN ASTIR: First tensile results of T91 and 316L steel after neutron irradiation in contact with liquid lead–bismuth eutectic

The TWIN ASTIR irradiation program [1] was aimed at determining the separate and possibly synergistic effects of a liquid lead–bismuth eutectic (LBE) environment and neutron irradiation. The materials in one capsule were irradiated in contact with LBE to a dose of about 1.5 dpa at a temperature between 460 and 490 °C and subsequently tested in liquid lead–bismuth eutectic environment at temperatures between 200 °C and 450 °C. This paper discusses the tensile results of T91 and 316L with and without irradiation while in contact with liquid lead–bismuth eutectic. The ferritic–martensitic T91 was softened by 50–100 MPa while the austenitic 316L steel showed a slight decrease in total elongation. Although no irradiation hardening was observed at the elevated irradiation temperature, the ferritic–martensitic T91 steel was prone to a certain extent of liquid metal embrittlement at 200 °C, 350 °C and 450 °C which was not affected by irradiation. The decrease in total elongation of the 316L is thought to be due to the neutron irradiation effect.