Mechanical properties of cryogenic structural materials for the ITER toroidal field coils

Nakajima, Hideo; Takano, Katsutoshi; Tsutsumi, Fumiaki; Kawano, Katsumi; Hamada, Kazuya; Iguchi, Masahide

This paper provides 4K tensile test results of a 316LN forged plate containing high nitrogen of 0.2%, which is produced by a foreign steel company. Since the forged plate showed uniform 4K strengths the foreign company could provide forgings to coil cases of the ITER Toroidal field coils in future. Quadratic curves to predict temperature dependence of yield and tensile strengths of 316LN, which are expressed as a function of carbon and nitrogen contents and strengths at room temperature, were verified by using 4K data of the forged plate tested in this study. It is concluded that the curves give good prediction and it can be used to specify the minimum strengths of 316LN. The results supports the basis of the material section of "Codes for Fusion Facilities; Rules on Superconducting Magnet Structure (2008)" issued by the Japan Society of Mechanical Engineers (JSME) in October 2008.