IRRADIATION CREEP-FATIGUE INTERACTION OF TYPE 316L STAINLESS-STEEL

Type 316L stainless steel samples in both, 20% cold-worked (cw) and re crystallised (re) conditions were exposed to strain controlled fatigue cycling in torsion at 400 degrees C during an irradiation with 19 MeV deuterons. The effect of irradiation creep induced stress relaxation on the fatigue life was studied by imposing a hold time at the minimum strain value in the loading cycle. For the cw material at strain rang es of 1.13% and 1.3%, the absolute stress values, tau(H), maintained d uring the hold time decreased with the number of cycles due to the irr adiation creep induced stress relaxation. A mean stress was built up. The number of cycles to failure was considerably reduced in comparison to continuous cycling tests under thermal conditions. For the rc mate rial at strain ranges of 1.03% and 1.4%, the values of tau(H) increase d with the number of cycles, despite the hold time imposed, due to irr adiation and/or cyclic hardening.