In-situ neutron stress measurements on dissimilar weld joint in thermal cycles

Akita, Koichi; Nishikawa, Satoru*; Shibahara, Masakazu*; Ikushima, Kazuki*; Suzuki, Hiroshi  ; Moriai, Atsushi; Harjo, S.   ; Aizawa, Kazuya  

To clarify the residual stress relaxation process in a dissimilar weld joint, the in-situ neutron stress measurements during thermal cycles were conducted using TAKUMI in J-PARC. The materials used for the base plates were a Ni-alloy (NCF600) and a stainless steel (SUS316L). The temperature range was from RT to 593 K. From the experimental results, it was found that residual stress of the Ni-alloy increased, while the residual stress of the stainless steel decreased, in the heating process. And, the residual stress of the Ni-alloy reaches the yield strength of the material in the heating process. It results in the redistribution of the residual stress, and therefore the residual stress relaxation occurs.