In Situ Tensile Testing of 316LN stainless steel at 4.5 K for fusion applications

316LN stainless steel is a prospective material for fusion reactor usedin large-scale superconducting magnets, where the operation temperature is 4.5 K. 316LN stainless steel for this application is subjected to various pre-treatments such as long-term annealing and stretching. Although mechanical performance of stainless steels at low temperatures have been well studied, how the deformation mechanisms change due to the pretreatment for 316LN steel has rarely been investigated. This becomes of great interests as stainless steels are known to trigger various deformation mechanisms from dislocation motion, twinning to phase transformation depending on their inherent properties and deformation conditions. Herein, we propose to use in situ tensile testing with neutron diffraction aiming to uncover the controlling deformation mechanisms of 316LN steel used for fusion applications.